Documents published in 2004 : Scipedia

Environmental capacity and European air transport:Stakeholder opinion and implications for modelling
D. Raper, M. Lever, A. Lieuwen, C. Thomas, M. McLellan, P. Upham

Collection of closed articles in transport research (2004). Vol. 2004, 9

Abstract
This paper reports on a survey of stakeholder views on airport environmental capacity, commissioned by EUROCONTROL. The survey found divergent opinion on the role of environmental limits in conceptions of environmental capacity. While there is widespread agreement that environmental constraints are likely to prove increasingly problematic for European aviation, there is also a wide range of opinion regarding institutional aspects of their management.
Abstract
This paper reports on a survey of stakeholder views on airport environmental capacity, commissioned by EUROCONTROL. The survey found divergent opinion on the role of environmental [...]
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PROBABILISTIC VALIDATION OF ADVANCED DRIVER ASSISTANCE SYSTEMS
O. Gietelink, B. Schutter, M. Verhaegen

Collection of closed articles in transport research (2005). Vol. 2005, 10

Abstract
We present a methodological approach for validation of advanced driver assistance systems, based on randomized algorithms. The new methodology is more efficient than conventional validation by simulations and field tests, especially with increasing system complexity. The methodology consists of first specifying the perturbation set and performance criteria. Then a minimum required number of samples and a relevant sampling space is selected. Next an iterative randomized simulation is executed, followed by validation with hardware tests. The concept is illustrated with a simple adaptive cruise control problem.
Abstract
We present a methodological approach for validation of advanced driver assistance systems, based on randomized algorithms. The new methodology is more efficient than conventional [...]
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A micro-simulation model system of departure time using a perception updating model under travel time uncertainty
T. Arentze, H. Timmermans, G. Tamminga, D. Ettema

Collection of closed articles in transport research (2005). Vol. 2005, 9

Abstract
Existing microscopic traffic models have often neglected departure time change as a possible response to congestion. In addition, they lack a formal model of how travellers base their daily travel decisions on the accumulated experience gathered from repetitively travelling through the transport network. This paper proposes an approach to account for these shortcomings. A micro-simulation approach is applied, in which individuals base their consecutive departure time decisions on a mental model. The mental model is the outcome of a continuous process of perception updating according to principles of reinforcement learning. Individuals’ daily travel decisions are linked to the traffic simulator SIAS-PARAMICS to create a simulation system in which both individual decision-making and system performance (and interactions between these two levels) are adequately represented. The model is applied in a case study that supports the feasibility of this approach.
Abstract
Existing microscopic traffic models have often neglected departure time change as a possible response to congestion. In addition, they lack a formal model of how travellers [...]
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Airline competition at European airports
S. Terwisga, T. Verburg, G. Burghouwt, K. Frenken

Collection of closed articles in transport research (2004). Vol. 2004, 8

Abstract
Hub-and-spoke networks of airlines create entry barriers at large hub airports. As a result, deregulation does not necessary lead to more competition. In this paper, airline competition at European airports in the 1990s is analysed. Results show important differences between airports, which are related to size and geography. At most airports, competition increased with the successful entrance of new competitors. Yet, competition decreased at hub airports and at airports in the northern periphery in Europe. Copyright (c) 2004 by the Royal Dutch Geographical Society KNAG.
Abstract
Hub-and-spoke networks of airlines create entry barriers at large hub airports. As a result, deregulation does not necessary lead to more competition. In this paper, airline [...]
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Worldwide Computing: Adaptive Middleware and Programming Technology for Dynamic Grid Environments
C. Varela, P. Ciancarini, K. Taura

Collection of closed articles in transport research (2005). Vol. 2005, 8

Abstract
Future-generations cyber-infrastructure must enable the dynamic coordinated composition of computing and information services. Resulting applications need to provide high-performance distributed computing to end users in a scalable, reliable and secure manner. This pervasive and ubiquitous grid computing infrastructure will view physical devices and computational agents uniformly, enabling radical improvement of existing applications, and opening the door for applications in entirely new domains. For example, wireless sensoractuator networks deployed in buildings and bridges can semi-automatically and cooperatively react to natural or man-made disasters in order to prevent human losses. Temperature, pressure, and stress-sensing devices can inform authorities about the probability of structural damage leading to collapse, can automatically activate fire extinguishing equipment, can help locate survivors and devise exit strategies, and can deviate traffic on emergency situations in semi-automated ways. Another example is virtual surgical planning, in which a surgeon simulates several surgery plans on a detailed computational model of a patient’s body. The surgeon can interactively analyze the effect of different plans on the patient’s body fluid dynamics. Another example is a distributed camera network coordinated by a real-time data mining component for airport surveillance and security. Unusual irregular patterns of human behavior can be detected and communicated promptly to authorities. A final example is a manned and unmanned aerial vehicle network that can exchange sensed information and plans of action, and combine them with terrain and map databases for decentralized coordinated air traffic control. These applications will directly benefit from coordinated computational resources offered by the future pervasive grid. To realize this pervasive grid vision, it is imperative to develop programming technology and modular middleware to facilitate systems development on highly heterogeneous and dynamic cyber-infrastructure. In closed grid environments, a centralized coordination module often needs to reserve dedicated network and computing resources for specific tasks. Furthermore, users are often expected to manually allocate resources and install any needed software on target computing environments. In contrast, open dynamic grid environments require coordination and resource management protocols to be automated. Resources in open grid environments can be organized into peer-to-peer networks. These networks are scalable because information lives in individual nodes and communication is highly, if not completely, decentralized. In an envisioned grid computing scenario, a process or data item will be created by a human user in a single node. The process or data item will get replicated and propagated by middleware Document type: Article
Abstract
Future-generations cyber-infrastructure must enable the dynamic coordinated composition of computing and information services. Resulting applications need to provide high-performance [...]
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Genetic algorithm approach to estimate transport energy demand in Turkey
S. Haldenbilen, H. Ceylan

Collection of closed articles in transport research (2005). Vol. 2005, 7

Abstract
Transport energy modeling is a subject of current interest among transport engineers and scientists concerned with problems of sustainable transport. Transport energy planning is not possible without a reasonable knowledge of past and present energy consumption and likely future demands. In this study, three forms of the energy demand equations are developed in order to improve transport energy demand estimation efficiency for future projections based on genetic algorithm (GA) notion. The Genetic Algorithm Transport Energy Demand Estimation (GATEDE) model is developed using population, gross domestic product and vehicle-km. All equations proposed here are linear and non-linear, of which one is linear, second is exponential and third is quadratic. The quadratic form of the GATEDE model provided better-fit solution to the observed data and can be used with a high correlation coefficient for Turkey's future transport energy projections. It is expected that this study will be helpful in developing highly applicable and productive planning for transport energy policies. The GATEDE gives transport energy demand in comparison with the other transport energy demand projections. The GATEDE model plans the sectoral energy demand of Turkey until 2020. (C) 2003 Elsevier Ltd. All rights reserved. C1 Pamukkale Univ, Fac Engn, Dept Civil Engn, PAU Insaat Muh Kinikli, TR-20017 Denizli, Turkey.
Abstract
Transport energy modeling is a subject of current interest among transport engineers and scientists concerned with problems of sustainable transport. Transport energy planning [...]
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Network dynamics in container transport by barge
T. Notteboom, R. Konings

Collection of closed articles in transport research (2004). Vol. 2004, 4

Abstract
In a time span of twenty years, container transport by barge has acquired a significant share in the hinterland modal split for containers of the load centres Rotterdam and Antwerp. In other European load centres, barge container transport as yet plays a modest role, but the interest in the barge option is growing. The growth in container volumes by barge and the increase of the number of seaports and inland terminals involved go hand in hand with fundamental spatial developments in the European inland terminal network.This paper addresses the organisational changes in the European barging industry that have taken place in the last twenty years and its impact on the spatial dynamics in the European container barge network. The paper analyses structural changes in liner service schedules by barge and the changing functional interdependencies between inland terminals in the network and organizational changes in the industry. The paper will conclude by discussing future perspectives for the spatial development of the barging network. Depuis les vingt dernières années, le transport conteneurisé par barges a connu une augmentation de part modale significative, des centres logistiques de Rotterdam et Anvers vers leurs arrière-pays. Malgré un intérêt croissant, la part du transport conteneurisé par barge demeure modeste dans les autres centres logistiques européens. L’augmentation du volume conteneurisé transporté par barges, ainsi que le nombre croissant de ports et terminaux intérieurs vont de pair avec les transformations spatiales fondamentales du réseau portuaire intérieur européen. Cet article aborde les changements organisationnels qui ont cours depuis les vingt dernières années dans l’industrie du transport conteneurisé par barges et leurs impacts sur les dynamiques spatiales dans les réseaux maritimes intérieurs européens. L’article analyse les changements structuraux dans les horaires des transporteurs par barges ainsi que les interdépendances fonctionnelles entre les réseaux de terminaux intérieurs européens et les changements organisationnels de l’industrie maritime. L’article conclut par une discussion sur les perspectives futures du développement spatial du réseau de transport maritime intérieur européen par barges.
Abstract
In a time span of twenty years, container transport by barge has acquired a significant share in the hinterland modal split for containers of the load centres Rotterdam and [...]
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Desirability of advanced driver assistance from road safety perspective: the case of ISA
R. Heijden, V. Marchau, E. Molin

Collection of closed articles in transport research (2005). Vol. 2005, 6

Abstract
The potential contribution of Advanced Driver Assistance Systems (ADAS) to traffic safety policies is currently unknown. In this article we first investigate how different ADAS might contribute to public goals on road traffic safety, based on accident statistics in the Netherlands. Next, the societal costs of ADAS implementation are qualitatively assessed. Intelligent speed adaptation (ISA) appears to be one of the most promising devices in terms of cost-effectiveness, as compared to other ADAS applications. Finally, the acceptance among potential ISA users is explored based on a survey among potential ISA users. The study points out that although the advantages of ISA are recognised by car drivers, their willingness to purchase and use ISA is strictly conditioned by the costs and functionality of the system.
Abstract
The potential contribution of Advanced Driver Assistance Systems (ADAS) to traffic safety policies is currently unknown. In this article we first investigate how different [...]
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Application of finite element model updating to a feed water pipeline of a nuclear power plant
P. Luukkanen, H. Haapaniemi, A. Saarenheimo, P. Nurkkala, A. Vepsä

Collection of closed articles in transport research (2005). Vol. 2005, 5

Abstract
This article is concerned with application of finite element model updating to a part of a secondary feed water pipeline of a VVER type nuclear power plant. A mathematical model of the pipeline was produced with finite element method. The pipeline was subjected to modal testing in three different conditions. The results of the modal testing were then compared with those predicted with the model. This comparison revealed discrepancies between these two sets of results. It is a commonly known fact that incorrect values of parameters in a model, among other things, do cause these discrepancies. In order to improve the correlation between the measured and the predicted results and hence improve the reliability of the model, the model was subjected to finite element model updating. In this updating process, incorrect values of parameters in a model are adjusted, so that a desired level of correlation between measured and predicted results is achieved. As a result, the correlation between the measured and the predicted results was improved. The bulk of the improvement was achieved by adjusting the values of those parameters that were associated with boundary conditions of the model.
Abstract
This article is concerned with application of finite element model updating to a part of a secondary feed water pipeline of a VVER type nuclear power plant. A mathematical [...]
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Technical feasibility of advanced driver assistance systems (ADAS) for road traffic safety.
K. Wevers, M. Lu, R. Heijden

Collection of closed articles in transport research (2005). Vol. 2005, 3

Abstract
This paper explores the technical feasibility of five Advanced Driver Assistance System (ADAS) functions to contribute to road traffic safety, to reach stated European (EU) and national road traffic safety targets. These functions -- enhanced navigation, speed assistance, collision avoidance, intersection support and lane keeping -- were selected from previous research as adequate substitutes for infrastructure related measures. State-of-the-art enabling technologies (like positioning, radar, laser, vision and communication) and their potential are analysed from a technical perspective, and possible obstacles for large-scale dedicated ADAS implementation for road traffic safety are discussed.
Abstract
This paper explores the technical feasibility of five Advanced Driver Assistance System (ADAS) functions to contribute to road traffic safety, to reach stated European (EU) [...]
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Computational human body models
J. Wismans, V. Dommelen, R. Happee

Collection of closed articles in transport research (2005). Vol. 2005, 2

Abstract
Computational human body models are widely used for automotive crashsafety research and design and as such have significantly contributed to a reduction of traffic injuries and fatalities. Currently crash simulations are mainly performed using models based on crash-dummies. However crash dummies differ significantly from the real human body and moreover crash dummies are only available for a limited set of body sizes. Models of the real human body offer some promising advantages including the prediction of injury mechanisms and injury criteria. In this paper, a review will be given of a number of developments in the field of occupant crash simulations in the past 40 years. Topics presented include history of occupant crash simulation codes, human body geometry, human body material modelling and model quality rating. A discussion on foreseen future developments in this field will conclude this paper. © 2005 Springer.
Abstract
Computational human body models are widely used for automotive crashsafety research and design and as such have significantly contributed to a reduction of traffic injuries [...]
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Power unit-cargo space link in transport
M. Dragovic, V. Maraš, R. Radmilovic

Collection of open articles in transport research (2005). Vol. 2005, 8

Abstract
This paper deals with transportation technology regarding links between power unit and cargo space. These links can be divided into two groups: rigid and flexible. Rigid link, established between power unit and cargo space, is dominant in maritime and road transport (sea ships and trucks), and occasionally in transport on inland waterways (self- propelled barges). Flexible link is used in the railroad transport (systems with trailers and semi trailers), and in inland waterway transport (push - towing and pulling systems, and combinations of the systems). The main goal of this research is determination of possible link types and organization of the means of transportation. Document type: Article
Abstract
This paper deals with transportation technology regarding links between power unit and cargo space. These links can be divided into two groups: rigid and flexible. Rigid link, [...]
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EVALUATION OF A DYNAMIC SIGNAL OPTIMISATION CONTROL MODEL USING TRAFFIC SIMULATION
H. Dia, S. Nigarnjanagool

Collection of open articles in transport research (2005). Vol. 2005, 6

Abstract
The objective of this paper is to demonstrate the feasibility of implementing a traffic signal optimisation model to improve real-time operations of traffic control systems. Advanced computer algorithms and traffic optimisation techniques can provide benefits over existing systems by reducing delays, improving travel times and reducing environmental emissions. The feasibility of the proposed approach is demonstrated by interfacing the traffic signal optimisation model to a microscopic traffic simulation tool, which enabled the evaluation of the benefits of the algorithm using computers in a controlled environment without disrupting traffic conditions. The main advantage of the proposed algorithm is its ability to detect dynamic changes in traffic flow conditions by using short-term historical demand data obtained from upstream vehicle loop detectors. The experimental results for under-saturated traffic conditions showed that the algorithm's performance was superior to optimal fixed time control. The results also confirmed that as traffic volumes reach saturated conditions, the performance of the algorithm decreased but remained better than what can be achieved by fixed time control systems. Document type: Article
Abstract
The objective of this paper is to demonstrate the feasibility of implementing a traffic signal optimisation model to improve real-time operations of traffic control systems. [...]
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THE RISK OF INJURY AND VEHICLE DAMAGE SEVERITY IN VEHICLE MISMATCHED SIDE IMPACT CRASHES IN BRITISH COLUMBIA
E. Desapriya, J. Kinney, I. Pike

Collection of open articles in transport research (2005). Vol. 2005, 3

Abstract
occupant protection offered by new passenger vehicles has improved, there has been growing concern about the harm that some vehicle designs may inflict on occupants of other vehicles with which they collide. Preceding analyses of crash statistics have clearly demonstrated the incompatibility between passenger sedan cars (PS) and pick-up trucks (PU) involved in side impact crashes in British Columbia. A comparison of light truck and passenger car crashes in previous literature reveals that light truck vehicles inflict greater harm than passenger cars for a number of reasons including their greater weight, stiffer structure, and higher ride height. These features place occupants of passenger cars at a disadvantage should they be involved in a collision with a light truck vehicle. The injury risk for passenger sedan car occupants is greater than the risk for pick-up truck occupants in two-vehicle crashes (Odds Ratio (OR) 1.87; 95% Confidence Interval (CI) 1.38-2.52). In addition, the risk of vehicle damage severity was increased for passenger cars compared with pick-up trucks (write off vehicle-OR 5.35; 95% CI 3.75-7.63, severely damaged vehicles-OR 5.87; 95% CI 4.79–7.19, moderately damaged vehicles-OR 2.86; 95% CI 2.44–3.36). There is strong justification for injury prevention experts and policy makers to step up motor vehicle crash injury prevention advocacy by implementing evidence-based policies to reduce rates of injury as a result of passenger sedan cars and pick-up trucks involved in side impact crashes in the province of British Columbia. Document type: Article
Abstract
occupant protection offered by new passenger vehicles has improved, there has been growing concern about the harm that some vehicle designs may inflict on occupants of other [...]
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ROAD ACCIDENT MODELS FOR LARGE METROPOLITAN CITIES OF INDIA
P. Valli

Collection of open articles in transport research (2005). Vol. 2005, 2

Abstract
In most of the metropolitan cities in India, the road use patterns are very different from those of developed countries. In Indian cities, roads are shared by non- motorized vehicles in large numbers. The rapid urbanization in India after independence has resulted in the faster development of 23 metropolitan cities as per the 2001 census. While the alarming increase in road accidents has become a major concern in the country, which takes away more than 90,000 lives every year, a significant share of it is from the major cities. The aim of the present paper is to develop models by analyzing the road accident data at an all India level as well as for major metropolitan cities. The data for the 25 year period from 1977 to 2001 were analyzed to build models to understand the nature and extent of the causes of accidents using the concept of Smeed's formula and Andressen's equations. On the basis of population and motor vehicle growth rates, which were derived from the empirical formulae, the above models were used for estimating road accidents in seven metropolitan cities for the years 2007 and 2010. As the variation between model and observed values is negligible, models seem to perform well for both equations. Document type: Article
Abstract
In most of the metropolitan cities in India, the road use patterns are very different from those of developed countries. In Indian cities, roads are shared by non- motorized [...]
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CROSS SITE TRANSFER SYSTEM DISPOSITION STUDY
T. Lee

Collection of restricted reports in transport research (2021). Vol. 2004, 2

Abstract
This document describes the cross-site transfer system and evaluates alternative regulatory process for closing the cross-site transfer system. The cross-site transfer system is a component of the single shell tank (SST) system. This document is intended to promote integration and coordination of removal and closure actions for the cross-site transfer system with U Plant closure activities and other facilities on the Central Plateau.
Abstract
This document describes the cross-site transfer system and evaluates alternative regulatory process for closing the cross-site transfer system. The cross-site transfer system [...]
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Layered autonomic systems
M. Ibrahim, R. Anthony, A. Butler

Collection of closed chapters of books in transport research (2021). Vol. 2005, 4

Abstract
We adopt a layered approach to autonomic systems to simplify the specification, implementation and evaluation of self-* behaviours. Autonomy is rendered in two dimensions and interfaces suitable for tool based development are incorporated. To exemplify our approach we present an emergent solution for airspace management. This is representative of many problems in which local neighbour interactions can be utilised to give stable and robust global behaviour.
Abstract
We adopt a layered approach to autonomic systems to simplify the specification, implementation and evaluation of self-* behaviours. Autonomy is rendered in two dimensions [...]
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Integration of driver support functions: The driver's point of view
C. Driel, B. van Arem

Collection of closed conferences in transport research (2021). Vol. 2004, 9

Abstract
Integration of driver support functions is a key issue in the development of in-vehicle systems that assist the driver with the driving task. This paper discusses a user needs survey that provides more insight into this issue from the perspective of the driver. Car drivers are asked to indicate their needs for driver assistance during certain driving tasks (e.g. congestion driving) and circumstances (e.g. reduced visibility). From this, consequences for the integration of functions can be deduced with respect to technology, HMI and functional operation. Preliminary results of a pilot test of the user needs survey are highlighted in this paper. These results indicate starting points for integrated driver assistance, such as the adaptability of systems based on personal needs for support, and the functional integration of driver support functions, for instance with respect to inter-vehicle communication.
Abstract
Integration of driver support functions is a key issue in the development of in-vehicle systems that assist the driver with the driving task. This paper discusses a user needs [...]
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Design and Optimization of Multi-bit Front-end Stage and Scaled Back-end Stages of Pipelined ADCs
P. Quinn, A. Roermund

Collection of closed conferences in transport research (2021). Vol. 2005, 2

Abstract
In this paper, an error analysis is presented to aid the design of a pipeline multi-bit front-end stage. It is demonstrated and quantified how the capacitor matching requirement can be reduced in high-resolution pipeline ADCs. The paper continues by analyzing the optimal design for low power of the scaled back-end stages. Finally, a model is proposed to estimate the power per stage, and hence total power consumption of the pipeline ADC.
Abstract
In this paper, an error analysis is presented to aid the design of a pipeline multi-bit front-end stage. It is demonstrated and quantified how the capacitor matching requirement [...]
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A neural network based car ownership model
Z. Yang, T. Feng

Collection of closed conferences in transport research (2021). Vol. 2004, 4

Abstract
With the economic growth and the improvement of living standards, car ownership in China is increasing rapidly. It exerts enormous pressure on transportation services. It is necessary to forecast China car ownership for urban transport planning, transport infrastructure improvement and traffic management in terms of economic level, urban configuration, traffic situation, and car-concerned policies. In this paper, the main factors affecting car ownership are analyzed and a model to estimate car ownership in China city with the BP neural network technology is developed. The model can take the sudden effect of some external factors such as political and economic factors on car ownership into account.
Abstract
With the economic growth and the improvement of living standards, car ownership in China is increasing rapidly. It exerts enormous pressure on transportation services. It [...]
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Aero-propulsive modeling of transport aircraft for air traffic management applications
M. Cavcar

Collection of closed conferences in transport research (2021). Vol. 2004, 2

Abstract
Collection of Technical Papers - AIAA Guidance, Navigation, and Control Conference -- 16 August 2004 through 19 August 2004 -- Providence, RI -- 64922 Aerodynamic and propulsive modeling of current aircraft fleet is vital for Air Traffic Management applications, especially for use in decision support tools to predict aircraft trajectories and simulation tools. There are various models already in use or proposed. A different aerodynamic and propulsive modeling is presented in this paper. The new model considers the compressibility effects and non-linear variations of the drag polar. In addition, the thrust and specific fuel consumption models proposed consider variations of these quantities both with altitude and the Mach number. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc.
Abstract
Collection of Technical Papers - AIAA Guidance, Navigation, and Control Conference -- 16 August 2004 through 19 August 2004 -- Providence, RI -- 64922 Aerodynamic and propulsive [...]
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Second-best congestion pricing schemes in the monocentric city
E. Verhoef

Collection of open conferences in research transport (2004). Vol. 2004, 100

Abstract
Paper submission from Erik Verhoef (everhoef@econ.vu.nl)Discussion Paper Submission Form - STEP 1This discussion paper abstract is submitted by Erik Verhoef (everhoef@econ.vu.nl)Template-Type: ReDIF-Paper 1.0Series: Tinbergen Institute Discussion PapersCreation-Date: Number: Author-Name: Erik T VerhoefAuthor-Email: everhoef@econ.vu.nlAuthor-Workplace-Name: VUTitle: SECOND-BEST CONGESTION PRICING SCHEMES IN THE MONOCENTRIC CITYAbstract:This paper considers second-best congestion pricing in the monocentric city, with endogenous residential density and endogenous labour supply. A spatial general equilibrium model is developed that allows consideration of the three-way interactions between urban density, traffic congestion and labour supply. Congestion pricing schemes are analyzed that are second-best ‘by design’ (and not because distortions exist elsewhere in the spatial economy), like cordon charging and flat kilometre charges. Both for Cobb-Douglas utility and for CES utility, the analyses suggest that the relative welfare losses from second-best pricing, compared to first-best pricing, are surprisingly small.
Abstract
Paper submission from Erik Verhoef (everhoef@econ.vu.nl)Discussion Paper Submission Form - STEP 1This discussion paper abstract is submitted by Erik Verhoef (everhoef@econ.vu.nl)Template-Type: [...]
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Constellations' Performance Analysis and Simulation for Cockpit and Passengers Aeronautical Services
L. Battaglia, P. Unger

Collection of open conferences in research transport (2004). Vol. 2004, 98

Abstract
Satellite based Air Traffic Management (ATM) and In-Flight Internet (IFI) services surely are among the most important ones that will be offered to airlines in the long term. In the design of any communication and security system, high performance must be paid for with high system costs. It is then clearly important, under the business case and technical perspective, to have fairly realistic estimates of the network resources that have to be provided, in order to guarantee the desired Quality of Service (QoS) and Security.
Abstract
Satellite based Air Traffic Management (ATM) and In-Flight Internet (IFI) services surely are among the most important ones that will be offered to airlines in the long term. [...]
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Planning Fundamental Urban Traffic Changes: Experiences With The Groningen Traffic Circulation Scheme
S. Tsubohara, H. Voogd

Collection of open conferences in research transport (2004). Vol. 2004, 97

Abstract
The city of Groningen, Netherlands, attracted much attention in the 1970s due to its fundamentally new traffic circulation scheme (VCP) that favored public transport, bicycles, and pedestrians above cars. The inner city was divided into 4 sectors and through traffic was made impossible by traffic restriction. Moving by car from one sector to another is possible only via the ring road around the inner city. In this paper, it is explained how this fundamental change could happen. This was a most interesting process as the suspicious public had to be convinced by municipal authorities without having references to successful examples elsewhere. It is illustrated that the most determining factor for success was the availability of political power to neglect opposing views. Both expert involvement and citizen participation were reduced to a minimum level.
Abstract
The city of Groningen, Netherlands, attracted much attention in the 1970s due to its fundamentally new traffic circulation scheme (VCP) that favored public transport, bicycles, [...]
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Experimental evaluation of an augmented reality visualization for directing a car driver's attention
H. Bubb, G. Klinker, M. Tönnis, C. Lange, C. Sandor

Collection of open conferences in research transport (2005). Vol. 2005, 133

Abstract
With recent advances of head-up display technology in cars, augmented reality becomes interesting in supporting the driving task to guide a driver's attention. We have set up an experiment to compare two different approaches to inform the driver about dangerous situations around the car. One approach used AR to visualize the source of danger in the driver's frame of reference while the other one presented information in an egocentric frame of reference. Both approaches were evaluated in user tests.
Abstract
With recent advances of head-up display technology in cars, augmented reality becomes interesting in supporting the driving task to guide a driver's attention. We have set [...]
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Wireless communications for airport surface: an evaluation of requirements
R. Apaza

Collection of open conferences in research transport (2005). Vol. 2005, 130

Abstract
Reliable airport surface communications is vital in today's airport operations. Present Federal Aviation Administration (FAA), airlines, and airport authority communications infrastructure is very diverse. Airports in the United States use either fiber optics, copper cable or leased telecommunications services to transport voice, data, and system monitoring information between FAA facilities and the air traffic control tower (ATCT). Copper cable is the most utilized in-airport communications medium by FAA. A large number of airports have an aging infrastructure that requires frequent maintenance and in some instances reliability is reduced due to performance limitations. A reduced number of FAA facilities use leased telecommunications services or fiber optic electronics to transport critical system information. Leased telecommunications services are costly and do not provide the diversity and redundancy required by large facilities. FAA has an ongoing effort to refurbish its infrastructure. Significant funds are budgeted to repair or replace aging or damaged copper cable. Similarly, funds are allocated to deploy fiber optic systems. The continuous growth of airports coupled with modernization efforts have made buried copper/fiber cables vulnerable to cuts/digs. The impact a cable cut has on the National Airspace System (NAS) can range depending on the location of the cable cut, the type of cable impacted, the time of day the cable is cut, and the airport where the cable cut occurs. Most copper cables installed by FAA are point to point architectures. Consequently, facilities serviced by copper cables frequently lack the diversity and redundancy offered by fiber optic loops. Airline and airport authority have similar efforts in place designed to improve the efficiency of their operation by enhancing their communications infrastructure and services. To develop a surface wireless communications system, an understanding of existing and future voice and data communications requirements is necessary. This paper explores existing airport surface communications infrastructure, along with the data and voice communication requirements, within the U.S. A requirements evaluation for the Dallas Fort Worth Airport, one of the largest airports in the U.S., is presented
Abstract
Reliable airport surface communications is vital in today's airport operations. Present Federal Aviation Administration (FAA), airlines, and airport authority communications [...]
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Traffic engineering eye diagram
K. Kowalik, M. Collier

Collection of open conferences in research transport (2005). Vol. 2005, 129

Abstract
It is said that a picture is worth a thousand words - this statement also applies to networking topics. Thus, to effectively monitor network performance we need tools which present the performance metrics in a graphical way which is also clear and informative. We propose a tool for this purpose which we call the traffic engineering eye diagram (TEED). Eye diagrams are used in digital communications to analyse the quality of a digital signal; the TEED can similarly he used in the traffic engineering field to analyse the load balancing ability of a TE algorithm. In this paper we describe how to create such TEEDs and how to use them to analyse and compare various traffic engineering approaches.
Abstract
It is said that a picture is worth a thousand words - this statement also applies to networking topics. Thus, to effectively monitor network performance we need tools which [...]
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A Holding Function for Conflict Probe Applications
J. Walton, D. McNally

Collection of open conferences in research transport (2004). Vol. 2004, 96

Abstract
Conflict Alerts for aircraft in holding patterns are often missed or in error due to fact that holding trajectories are not modeled in Conflict Alert or Conflict Probe logic. In addition, a controller in one sector may not know when aircraft are holding in a neighboring sector. These factors can lead to an increased potential for loss of separation while aircraft are flying in holding patterns. A holding function for conflict probe applications has been developed and tested with air traffic data from Fort Worth Center. The holding function automatically determines when an aircraft enters a holding pattern, builds a holding region around the pattern and then probes the region for conflict with other traffic. The operational concept of use assumes that air traffic controllers are very busy during periods when aircraft are in holding and therefore don't have time to manually enter information which defines a holding pattern and activates conflict probing. For this reason, it is important the holding function automatically detect aircraft in holding and compute a holding region for conflict analysis. The controller is then alerted if other aircraft are predicted to fly through the holding region at the holding altitude.
Abstract
Conflict Alerts for aircraft in holding patterns are often missed or in error due to fact that holding trajectories are not modeled in Conflict Alert or Conflict Probe logic. [...]
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Modifications to the Design of the Multi-Center Traffic Management Advisor Distributed Scheduler
S. Landry

Collection of open conferences in research transport (2004). Vol. 2004, 95

Abstract
In a number of Air Route Traffic Control Centers (ARTCCs) around the United States, time-based metering of arrival aircraft is being used to control air traffic demand on busy airports. In attempting to introduce time-based metering for airports in the Northeast corridor (such as Philadelphia International Airport - PHL), several technical challenges were identified. Single-center Traffic Management Advisor (TMA), the most advanced decision support tool (DST) used for this purpose, is limited to managing traffic within one center, and to within about a 250 nautical mile (nm) radius. To overcome these restrictions, NASA engineers designed a distributed scheduling system, which uses a loosely coupled network of schedulers that can be extended across ARTCC boundaries and out beyond 400nm. The resulting design was incorporated into the Multi-center Traffic Management Advisor (McTMA), a traffic management DST whose implementation has undergone research and testing on PHL arrivals. This testing has yielded several key insights into the distributed scheduler, resulting in significant changes to the algorithm and underlying software. Three of these are discussed in this paper. First, the method used to account for and distribute unused capacity has been changed. Second, the resolution of the mechanism used to distribute restrictions has been increased. Lastly, an inconsistency in behavior between how close-in departures were being scheduled as compared to airborne aircraft was corrected.
Abstract
In a number of Air Route Traffic Control Centers (ARTCCs) around the United States, time-based metering of arrival aircraft is being used to control air traffic demand on [...]
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Development of a Causal Model for Air Transport Safety
E. Smith, A. Roelen, D. Kurowicka, A. Hale, R. Cooke, B. Ale, L. Bellamy, L. Goossens

Collection of open conferences in research transport (2005). Vol. 2005, 124

Abstract
The development of the Dutch international airport Schiphol has been the subject of fierce political debate for several decades. One of the considerations has been the safety of the population living around the airport. In the debate about the acceptability of the risks associated with the air traffic above The Netherlands the need has arisen to gain a more thorough understanding of the accident genesis in air traffic, with the ultimate aim of improving the safety situation in air traffic in general and around Schiphol in particular. To this end a research effort has been started in order to develop causal models for air traffic risks in the expectation that these will ultimately give the necessary insights. The first step is to organise the information available in accident databases.Copyright © 2005 by ASME
Abstract
The development of the Dutch international airport Schiphol has been the subject of fierce political debate for several decades. One of the considerations has been the safety [...]
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Highway traffic state estimation using improved mixture kalman filters for effective ramp metering control
R. Horowitz, X. Sun, L. Munoz

Collection of open conferences in research transport (2004). Vol. 2004, 93

Abstract
In this paper, we use a cell transmission model based switching state-space model to estimate vehicle densities and congestion modes at unmeasured locations on a highway section. The mixture Kalman filter algorithm, which is based on sequential Monte Carlo method, is employed to approximately solve the difficult problem of inference on a switching state-space model with an unobserved discrete state. We propose a scheme to prevent the risk of weight underflow and to introduce forgetting. The estimation results show that comparable accuracies can be achieved using either a small or a large number of sampling sequences, thus make it possible to carry out efficient online filtering. Underflow prevention and forgetting improves estimation accuracy in our examples. On average, a mean percentage error of approximately 10% is achieved for the vehicle density estimation. The estimation performance is consistent with data sets from various days.
Abstract
In this paper, we use a cell transmission model based switching state-space model to estimate vehicle densities and congestion modes at unmeasured locations on a highway section. [...]
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Games networks play a game theoretic approach to networks
A. Rextin, Z. Uzmi, Z. Irfan

Collection of open conferences in research transport (2004). Vol. 2004, 92

Abstract
Traditional network protocols such as TCP/IP require cooperation between traffic sources to achieve optimal network performance. This approach does not always work, as evident by frequent congestion problems in the Internet. Recent research in protocol design using game theory removes this limitation by modeling traffic sources as competing players and results in efficient and fair distribution of resources. This paper provides theoretical background of the game theoretic approach as applied to networks, describes some previously proposed schemes for minimizing network congestion, elaborates on pricing mechanisms and discusses game-theoretic routing solutions. Pricing provides a feasible solution for congestion control but application of distributed algorithmic mechanism design (DAMD) can be adapted for congestion control.
Abstract
Traditional network protocols such as TCP/IP require cooperation between traffic sources to achieve optimal network performance. This approach does not always work, as evident [...]
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Congestion management of self similar ip traffic - application of the RED scheme
S. Suresh, O. Gol

Collection of open conferences in research transport (2005). Vol. 2005, 120

Abstract
Schemes described in the literature on network congestion management are in general based on queue management. Also it is widely accepted that Poisson model is not sufficient to characterize the traffic in current Internet. With this in view, in this paper, an attempt has been made by proposing a modified RED (random early detection) algorithm for traffic congestion management in IP networks with self-similar input. "We first present the basic scheme of RED as proposed by Floyd et.al., for the Poisson input model, and then explain the modification to the algorithm that we propose for a self similar IP traffic input. We take into consideration the probability values corresponding to the average queue lengths for computing the marking/dropping probability. Verification of the equation proposed vis-a-vis that of Floyd has been done by taking simulated values available for self-similar traffic. Results are tabulated and graphically shown. It has also been shown that under certain conditions, our modified equation for the marking probability, reduces to the one proposed by Floyd.
Abstract
Schemes described in the literature on network congestion management are in general based on queue management. Also it is widely accepted that Poisson model is not sufficient [...]
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On wavelength assignment in optical burst switched networks
G. Rouskas, J. Teng

Collection of open conferences in research transport (2004). Vol. 2004, 91

Abstract
fundamental assumption underlying most studies of optical burst switched (OBS) networks is that full wavelength conversion is available throughout the network. In practice however, economic and technical considerations are likely to dictate a more limited and sparse deployment of wavelength converters in the optical network. Therefore, we expect wavelength assignment policies to be an important component of OBS networks. In this paper, we explain why wavelength selection schemes developed for wavelength routed networks are not appropriate for OBS. We then develop a suite of adaptive and non-adaptive policies for OBS switches. We also apply traffic engineering techniques to reduce wavelength contention through traffic isolation. Our performance study indicates that, in the absence of full conversion capabilities, intelligent choices in assigning wavelengths to bursts at the source can have a profound effect on the burst drop probability in an OBS network.
Abstract
fundamental assumption underlying most studies of optical burst switched (OBS) networks is that full wavelength conversion is available throughout the network. In practice [...]
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Razor: a low-power pipeline based on circuit-level timing speculation
D. Blaauw, T. Mudge, N. Kim, D. Ernst, T. Pham, S. Pant, K. Flautner, R. Rao, C. Ziesler, T. Austin, S. Das

Collection of open conferences in research transport (2004). Vol. 2004, 89

Abstract
With increasing clock frequencies and silicon integration, power aware computing has become a critical concern in the design of embedded processors and systems-on-chip. One of the more effective and widely used methods for power-aware computing is dynamic voltage scaling (DVS). In order to obtain the maximum power savings from DVS, it is essential to scale the supply voltage as low as possible while ensuring correct operation of the processor. The critical voltage is chosen such that under a worst-case scenario of process and environmental variations, the processor always operates correctly. However, this approach leads to a very conservative supply voltage since such a worst-case combination of different variabilities is very rare. In this paper, we propose a new approach to DVS, called Razor, based on dynamic detection and correction of circuit timing errors. The key idea of Razor is to tune the supply voltage by monitoring the error rate during circuit operation, thereby eliminating the need for voltage margins and exploiting the data dependence of circuit delay. A Razor flip-flop is introduced that double-samples pipeline stage values, once with a fast clock and again with a time-borrowing delayed clock. A metastability-tolerant comparator then validates latch values sampled with the fast clock. In the event of timing error, a modified pipeline mispeculation recovery mechanism restores correct program state. A prototype Razor pipeline was designed in a 0.18 /spl mu/m technology and was analyzed. Razor energy overhead during normal operation is limited to 3.1%. Analyses of a full-custom multiplier and a SPICE-level Kogge-Stone adder model reveal that substantial energy savings are possible for these devices (up to 64.2%) with little impact on performance due to error recovery (less than 3%).
Abstract
With increasing clock frequencies and silicon integration, power aware computing has become a critical concern in the design of embedded processors and systems-on-chip. One [...]
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Influence of Pressure in Pipeline Design: Effective Axial Force
O. Fyrileiv, L. Collberg

Collection of open conferences in research transport (2005). Vol. 2005, 118

Abstract
This paper discusses use of the effective axial force concept in offshore pipeline design in general and in DNV codes in particular. The concept of effective axial force or effective tension has been known and used in the pipeline and riser industry for some decades. However, recently a discussion about this was initiated and doubt on how to treat the internal pressure raised. Hopefully this paper will contribute to explain the use of this concept and remove the doubts in the industry, if it exists at all. The concept of effective axial force allows calculation of the global behaviour without considering the effects of internal and/or external pressure in detail. In particular, global buckling, so-called Euler buckling, can be calculated as in air by applying the concept of effective axial force. The effective axial force is also used in the DNV-RP-F105 “Free spanning pipelines” to adjust the natural frequencies of free spans due to the change in geometrical stiffness caused by the axial force and pressure effects. A recent paper claimed, however, that the effect was the opposite of the one given in the DNV-RP-F105 and may cause confusion about what is the appropriate way of handling the pressure effects. It is generally accepted that global buckling of pipelines is governed by the effective axial force. However, in the DNV Pipeline Standard DNV-OS-F101, also the local buckling criterion is expressed by use of the effective axial force concept which easily could be misunderstood. Local buckling is, of course, governed by the local stresses, the true stresses, in the pipe steel wall. Thus, it seems unreasonable to include the effective axial force and not the true axial force as used in the former DNV Pipeline Standard DNV’96. The reason for this is explained in detail in this paper. This paper gives an introduction to the concept of effective axial force. Further it explains how this concept is applied in modern offshore pipeline design. Finally the background for using the effective axial force in some of the DNV pipeline codes is given.Copyright © 2005 by ASME
Abstract
This paper discusses use of the effective axial force concept in offshore pipeline design in general and in DNV codes in particular. The concept of effective axial force or [...]
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Graph Coloring for Air Traffic Flow Management
N. Barnier, P. Brisset

Collection of open conferences in research transport (2004). Vol. 2004, 88

Abstract
The aim of Air Traffic Flow Management (ATFM) is to enhance the capacity of the airspace while satisfying Air Traffic Control constraints and airlines requests to optimize their operating costs. This paper presents a design of a new route network that tries to optimize these criteria. The basic idea is to consider direct routes only and to vertically separate intersecting flows of aircrafts by allocating distinct flight levels. This problem is a graph coloring problem that we tackle using Constraint Programming and a greedy algorithm to find cliques of the constraint graph which are used to post global constraints. Through the search for optimal solutions minimizing the number of distinct flight levels allocated, symmetries among equivalent flight levels are dynamically broken, and the variable ordering is guided by the cliques found in the first static step. With an implementation using FaCiLe, our Functional Constraint Library, optimality is achieved for all flow sizes except the smallest one, while the corresponding number of flight levels could fit in the current airspace structure. However, many other constraints should be added to this very simplified model to obtain an operational route network, such that the conclusion is rather the validation of the concept of vertical separation of large flows. This graph coloring technique has also been tested on various benchmarks, featuring good results on real-life instances, which systematically appear to contain large cliques.
Abstract
The aim of Air Traffic Flow Management (ATFM) is to enhance the capacity of the airspace while satisfying Air Traffic Control constraints and airlines requests to optimize [...]
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Effect of Uncertainty on En Route Descent Adviser (EDA) Predictions
D. Schleicher, K. Mueller, R. Bortins, R. Coppenbarger

Collection of open conferences in research transport (2004). Vol. 2004, 87

Abstract
The En Route Descent Advisor (EDA) is one of the Center TRACON Automation System (CTAS) decision support tools under development at the NASA Ames Research Center. EDA generates maneuver advisories for arrival aircraft to meet scheduled arrival times at the arrival meter fix, sometimes 20 – 25 minutes ahead of the aircraft’s scheduled meter fix arrival time. This work determined the sensistivity of the EDA advisories to system uncertainties, including initial condition, environmental, and aircraft performance data errors. Using a Monte Carlo simulation that incorporates a Matlab Trajectory Synthesizer (TS) simulation, the sensitivities of the EDA predicted trajectory to these data error sources were obtained. The key metric is the meter fix crossing time error since this metric directly measures the performance of EDA. This performance analysis involved a minimum of 200 Monte Carlo trials per error parameter. In addition to the single aircraft performance analysis, the impact of aircraft prediction errors on conflict detection between closely-spaced aircraft was also explored. These Monte Carlo performance analyses determined how robust the EDA advisories are to input parameter uncertainties.
Abstract
The En Route Descent Advisor (EDA) is one of the Center TRACON Automation System (CTAS) decision support tools under development at the NASA Ames Research Center. EDA generates [...]
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Low voltage high-SNR pipeline data converters
J. Li, C. Myers, D. Chang, U. Moon

Collection of open conferences in research transport (2004). Vol. 2004, 85

Abstract
design strategy is presented for obtaining high-SNR (14 bits or higher) in a low voltage pipeline data converter. This is accomplished with the removal of the S/H input stage and the use of a rail-to-rail input stage. The rail-to-rail input requires a reference calibration scheme to maintain converter linearity, and is implemented as a radix calibration.
Abstract
design strategy is presented for obtaining high-SNR (14 bits or higher) in a low voltage pipeline data converter. This is accomplished with the removal of the S/H input stage [...]
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Surface Management System Field Trial Results
Y. Jung, T. Carniol, C. Brinton, S. Rogowski, L. Stell, S. Atkins

Collection of open conferences in research transport (2004). Vol. 2004, 83

Abstract
NASA Ames Research Center, in cooperation with the FAA, has completed research and development of a proof-of-concept Surface Management System (SMS). This paper reports on two recent SMS field tests as well as final per-formance and benefits analyses. Field tests and analysis support the conclusion that substantial portions of SMS technology are ready for transfer to the FAA and deployment throughout the National Airspace System (NAS). Other SMS capabilities were accepted in concept but require additional refinement for inclusion in subsequent de-velopment spirals. SMS is a decision support tool that helps operational specialists at Air Traffic Control (ATC) and NAS user facilities to collaboratively manage the movements of aircraft on the surface of busy airports, thereby im-proving capacity, efficiency, and flexibility. SMS provides accurate predictions of the future demand and how that demand will affect airport resources – information that is not currently available. The resulting shared awareness enables the Air Traffic Control Tower (ATCT), Terminal Radar Approach Control (TRACON), Air Route Traffic Control Center (ARTCC), and air carriers to coordinate traffic management decisions. Furthermore, SMS uses its ability to predict how future demand will play out on the surface to evaluate the effect of various traffic management decisions in advance of implementing them, to plan and advise surface operations. The SMS concept, displays, and algorithms were evaluated through a series of field tests at Memphis International Airport (MEM). An operational trial in September, 2003 evaluated SMS traffic management components, such as runway configuration change planning; shadow testing in January, 2004 tested tactical components (e.g., Approval Request (APREQ) coordina-tion, sequencing for departure, and Expected Departure Clearance Time (EDCT) compliance). Participants in these evaluations rated the SMS concept and many of the traffic management displays very positively. Local and Ground controller displays will require integration with other automation systems. Feedback from FAA and NAS user par-ticipants support the conclusion that SMS algorithms currently provide information that has acceptable and benefi-cial accuracy for traffic management applications. Performance analysis results document the current accuracy of SMS algorithms. Benefits/cost analysis of delay cost reduction due to SMS provides the business case for SMS deployment.
Abstract
NASA Ames Research Center, in cooperation with the FAA, has completed research and development of a proof-of-concept Surface Management System (SMS). This paper reports on [...]
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A Collaborative Approach to Trajectory Modeling Validation
R. Vivona, M. Paglione, S. Swierstra, S. Green, C. Garcia-Avello

Collection of open conferences in research transport (2005). Vol. 2005, 111

Abstract
service providers view the growth in future air traffic demand exceeding that of capacity, making it increasingly difficult to maintain yet alone improve the current levels of safety and efficiency. Advanced air traffic management (ATM) and flight deck decision support tool (DST) capabilities are seen as the functional enablers of the future ATM concepts needed to increase capacity by two-threefold. Such automation will provide support in flight data, metering, and conflict prediction/resolution functions to name a few. DST capabilities depend directly on the performance of the underlying trajectory predictor(s) (TP) that provide the anticipated future path of the aircraft. The accuracy of the TP is critical to the success of these DST functions. A common TP validation strategy has been developed for universal application to each element of the TP structure. The TP validation strategy is complemented by a broad database of actual trajectory recordings posted on a Web site and formatted in the extensible markup language (XML). The methodology presented here provides the process for any developer to utilize this database to validate and improve their TP's performance. This paper outlines the TP validation strategy, describes the various types of validation data provided, XML format, and tools developed.
Abstract
service providers view the growth in future air traffic demand exceeding that of capacity, making it increasingly difficult to maintain yet alone improve the current levels [...]
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Assessing the Impact of a New Air Traffic Control Instruction on Flight Crew Activity
N. Pene, L. Rognin, C. Hebraud, K. Zeghal, E. Hoffman

Collection of open conferences in research transport (2004). Vol. 2004, 80

Abstract
new allocation of tasks between controller and flight crew is envisaged as one possible option to improve air traffic management and in particular the sequencing of arrival flows. It relies on a set of new spacing instructions where the flight crew can be tasked by the controller to maintain a given spacing with respect to a designated aircraft. In order to assess the benefits and limits of airborne spacing, two streams of air and ground experiments were conducted. The latest air experiment aimed at assessing the feasibility of time-based spacing in final approach and its impact on flight crew activity. Flight crews were tasked to maintain a spacing behind a target aircraft, through adjustments of the selected speed. Their feedback on feasibility was generally positive despite an increase of mental effort which remained acceptable. Every crew successfully achieved the spacing task: the deviation was maintained within the tolerances. The impact on flight crews’ activity was assessed through the speed actions needed to perform the spacing task. The average number of speed actions was less than 1 per minute, and most were small adjustments comprised between -15kt and +5kt. The effect of various reactions of preceding aircraft under airborne spacing will be investigated in further experiments, as well as monitoring load and scanning pattern.
Abstract
new allocation of tasks between controller and flight crew is envisaged as one possible option to improve air traffic management and in particular the sequencing of arrival [...]
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A pragmatic definition of elephants in internet backbone traffic
K. Papagiannaki, P. Thiran, K. Salamatian, C. Diot, N. Taft, S. Bhattacharyya

Collection of open conferences in research transport (2004). Vol. 2004, 79

Abstract
Studies of the Internet traffic at the level of network prefixes, fixed length prefixes, TCP flows, AS’s, and WWW traffic, have all shown that a very small percentage of the flows carries the largest part of the information. This behavior is commonly referred to as “the elephants and mice phenomenon”. Traffic engineering applications, such as re-routing or load balancing, could exploit this property by treating elephant flows differently. In this context, though, elephants should not only contribute significantly to the overall load, but also exhibit sufficient persistence in time. The challenge is to be able to examine a flow’s bandwidth and classify it as an elephant based on the data collected across all the flows on a link. In this paper, we present a classification scheme that is based on the definition of a separation threshold, that elephants have to exceed. We introduce two single-feature classification schemes, and show that the resulting elephants are highly volatile. We then propose a two-feature classification scheme that incorporates temporal characteristics and show that this approach is more successful in isolating elephants that exhibit consistency thus making them more attractive for traffic engineering applications.
Abstract
Studies of the Internet traffic at the level of network prefixes, fixed length prefixes, TCP flows, AS’s, and WWW traffic, have all shown that a very small percentage of [...]
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Performance evaluation of survivable multifiber WDM networks
Y. Luo, N. Ansari

Collection of open conferences in research transport (2004). Vol. 2004, 78

Abstract
This article proposes a survivability evaluation model for multifiber WDM networks, in which the extended layered graph is developed to jointly optimize the wavelength routing and wavelength assignment problems, and three different edge cost functions are evaluated in terms of traffic engineering. Linear programming (LP) equations are formulated to optimally determine the working lightpath and the corresponding protection lightpath under the schemes of shared protection and dedicated protection. The extensive simulations show that shared protection with the fiber and wavelength-based cost function provides the best survivability.
Abstract
This article proposes a survivability evaluation model for multifiber WDM networks, in which the extended layered graph is developed to jointly optimize the wavelength routing [...]
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Evaluating techniques for exploiting instruction slack
Y. Chin, J. Sheu, D. Brooks

Collection of open conferences in research transport (2004). Vol. 2004, 77

Abstract
In many workloads, 25% to 50% of instructions have slack allowing them to be delayed without impacting performance. To exploit this slack, processors may implement more power-efficient, longer latency pipelines or provide dynamically scaled pipelines using multiple clock domains. Issuing instructions with slack to slower pipelines can result in substantial power savings, with minimal performance loss. Considering both dynamic and static power dissipation, we found that by using longer latency pipelines the power of functional unit pipelines decreases by 20% to 55% with a performance impact of 0% to 3% for SPEC2000 and MediaBench workloads. Dynamic scaling reduces the performance loss in intense multimedia workloads by up to 2%, but achieves lower power savings.
Abstract
In many workloads, 25% to 50% of instructions have slack allowing them to be delayed without impacting performance. To exploit this slack, processors may implement more power-efficient, [...]
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Potential Functions for En-Route Air Traffic Management and Flight Planning
J. Crassidis, K. Ramamoorthy, T. Singh

Collection of open conferences in research transport (2004). Vol. 2004, 75

Abstract
This paper proposes an object oriented methodology and use of potential functions for efficient solutions to en-route air traffic management and flight planning in a complex airspace system. In this object oriented methodology, different objects, e.g., weather, Special Use Airspace (SUA), traffic, etc., and their attributes, e.g., weather orientation, SUA geometry, traffic density, etc., are defined by using potential functions. The interaction of the object of interest (host aircraft) and environment is modeled through an artificial potential field, whose interaction model is simple and well defined. This helps in framing a simple algorithm and produces efficient and complete solutions. The path planning and conflict detection and resolution algorithms developed for this methodology provide efficient solutions in the comprehensively defined environment model in which uncertainty is very limited. The algorithms have been implemented in a low-level flight planner. Results to validate the operation of the algorithm and feasibility of the methodology will be provided and a functional layout of the flight planner is provided. Introduction: The Distributed Air/Ground – Traffic Management (DAG-TM) concept [8] for Free Flight has been well defined for all phases of flight. The free flight in en-route airspace not only represents the largest portion of flight but also the most critical component to maintain continuous traffic flow in the National Airspace System (NAS). The DAG-TM Concept Elements (CE) 5, 6 and 7 dealing with en-route airspace has provided clear definition of the concept, requirements and solutions [3,5,6,7]. The problem in en-route air traffic has been believed to be issuance of inefficient resolution and difficulties in conformance to traffic flow management (TFM) constraints. The root cause for these problems has been identified as uncertainty in the trajectory information, lack of user preference and workload limitations [5,6,7]. The DAG-TM concept element 5, 6 and 7 proposes various efficient solutions by using decision support tools and collaboration. The decision support tools being developed for these problems should consider many factors that influence a problem and bring out efficient solutions that do not result in further complexity. One approach this paper suggests is an object oriented approach. Problems in a complex system like airspace can be best solved if an object oriented approach is applied. In this paper, potential functions are used which provide a convenient way to do this. Artificial potential fields have been used extensively in both robotics and air traffic [11,12,13,14,15,16]. Dynamic force fields have also been used, which are similar to potential functions and they carry more information than potential functions [10]. A methodology, named as potential functions methodology, will be introduced to use the potential functions to model the airspace in an object oriented approach. Potential functions of different shapes and strengths are used to represent various objects and their attributes in the airspace. The host-centric interaction between the host aircraft and the environment is modeled by using an appropriate potential charge, which exerts the force of attraction and repulsion. The 4D information of a potential function (3D shape and strength) is enough to formulate any problem which provides 4D trajectory information (3D location and time). Based on this methodology, two path planning algorithms are developed. One for flight route planning and the other for conflict detection and resolution and local trajectory generation. Many Conflict Detection and Resolution (CD&R) algorithms have been developed [3,4], but few have implemented coordinated resolution methods [1]. The CD&R algorithm developed under this methodology exhibits a rule based implicitly coordinated decision making for conflict resolution. The algorithms have been implemented in a low level flight planner, which features the basic functions of flight planning. This shows the
Abstract
This paper proposes an object oriented methodology and use of potential functions for efficient solutions to en-route air traffic management and flight planning in a complex [...]
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Future vision of globally harmonized national airspace system with concepts of operations beyond year 2020
S. Mohleji, P. Ostwald

Collection of open conferences in research transport (2004). Vol. 2004, 74

Abstract
laid out in the National Airspace Systems (NAS) Operational Evolution Plan (EOP), the Federal Aviation Administration (FAA) and the aviation community are planning to make significant investment in NAS improvements over the next ten years. These enhancements involve implementation of communication, navigation and surveillance (CNS) technologies, and automation of ground systems in order to improve efficiency, safety, capacity and security. However, the mode of operations during this time frame is expected to continue as it is today. A number of research efforts are underway to consider significant changes to NAS operations beyond the OEP. This paper presents a vision of year 2020 and beyond based on a number of new paradigms that provides a globally harmonized service to conventional aircraft, uninhabited and space-launch vehicles. The key paradigms are: 1) a multi-faceted airport structure of well connected hubs, spoke, satellite and smaller airports; 2) multi-level CNS architecture for seamless and secured operations; 3) problem-free flight planning independent of look ahead times; 4) flexible sector boundaries based on equitable workload; and 5) a universal information service assuring uniformity and security of real time information to all stakeholders and service provider decision support systems (DSS). Potential make up of future air traffic is discussed including a significant number of non-scheduled flights such as on-demand service, charter, ravel club, fractional and short-haul intra-city operations. A concept of system wide information management (SWIM) that provides a virtual electronic collaboration space is described. The operational concepts fully support self-delivery and self-separation for appropriately equipped aircraft. New roles for service providers at national, regional and local air traffic
Abstract
laid out in the National Airspace Systems (NAS) Operational Evolution Plan (EOP), the Federal Aviation Administration (FAA) and the aviation community are planning to make [...]
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An enhanced dropping scheme for proportional differentiated services
N. Ansari, J. Zeng

Collection of open conferences in research transport (2004). Vol. 2004, 72

Abstract
the DiffServ architecture is gaining ground, traffic engineering requires major adjustments. In addition, the measurement-based strategy gas been widely adopted owing to its advantages of flexibility and easy adaptation. This article reviews measurement-based dropping schemes. Based on the definition and investigation of the "packet shortage" phenomenon, an enhanced dropping scheme for the proportional differentiated packet loss, referred to as "debt-aware," is proposed. Simulation parameters, as compared to a typical proportional dropping mechanism. More simulations have been applied to demonstrate the merits of this improved method.
Abstract
the DiffServ architecture is gaining ground, traffic engineering requires major adjustments. In addition, the measurement-based strategy gas been widely adopted owing to its [...]
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Trajectory-Oriented Operations with Limited Delegation: An Evolutionary Path to NAS Modernization
T. Callantine, P. Kopardekar, T. Prevot, E. Palmer, V. Battiste, N. Smith

Collection of open conferences in research transport (2004). Vol. 2004, 71

Abstract
*† ‡ § ** †† This paper presents a concept named Trajectory Oriented Operations with Limited Delegation. The concept provides a framework for transforming NAS operations in line with global modernization trends. It enables the evolutionary introduction of trajectory oriented air traffic tools and airborne separation assistance systems. Specific implementation examples for several evolutionary phases are presented. The tools and procedures prototyping this concept will be further developed and tested in simulations at NASA Ames Research Center as part of the NextNAS project.
Abstract
*† ‡ § ** †† This paper presents a concept named Trajectory Oriented Operations with Limited Delegation. The concept provides a framework for transforming NAS operations [...]
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A Simplified Backstepping Design for 3D Time-based Aircraft Relative Guidance
F. Mora-Camino, J. Loscos, T. Miquel, F. Casaux

Collection of open conferences in research transport (2004). Vol. 2004, 70

Abstract
International audience; The delegation to the flight crew of some tasks currently performed by air traffic controllers provides new perspectives to potentially increase air traffic control capacity. The objective of this communication is to provide technical insight into the airborne devices and algorithms which may be used to automatically perform merging and station keeping operations. Indeed, these maneuvers in the field of civil aviation seem difficult to be performed manually and may result in this case in an increase of the flight crew workload. Nevertheless new automated functions onboard aircraft could help to overcome this limitation. This paper investigates the design of a new autopilot mode dedicated to merging and station keeping maneuvers behind a leading aircraft. The proposed relative guidance law considers a 3-D relative motion, including constant wind and lateral, longitudinal and vertical control. It is based on vectorial backstepping and takes advantage of the skewsymmetric matrix which appears in the relative motion equations. An alternative "simplified" design based on a matrix form of the Young's inequality is also presented in order to simplify the computation of the guidance law. Then, an illustrative example is discussed and conclusions are raised.
Abstract
International audience; The delegation to the flight crew of some tasks currently performed by air traffic controllers provides new perspectives to potentially increase air [...]
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TransMilenio: A High Capacity - Low Cost Bus Rapid Transit System Developed for Bogotá, Colombia
E. Sandoval, D. Hidalgo

Collection of open conferences in research transport (2004). Vol. 2004, 69

Abstract
TransMilenio is a bus rapid transit system in Bogota, Colombia resulting from a successful public-private partnership. The system comprises specialized infrastructure including exclusive lanes for high capacity articulated buses, efficient private operation, advanced fare collection system, and a new public authority for planning, developing and controlling the system. TransMilenio started operations in December 2000. By April 2002 it moved 650,000 passengers/day in 38 Km busways, 62 stations, 470 articulated buses and 300 feeder buses operating 124 Km routes. Extensions will continue in the next 16 years to cover 85% of the daily trips in the city. TransMilenio is a high quality and sustainable transport solution, at a very low cost for the tax payer and the direct users. This paper presents the situation of Bogota, the overall mobility strategy in which the mass transit system is embedded, the components of TransMilenio, the implementation strategy, and the results after five months of operation.
Abstract
TransMilenio is a bus rapid transit system in Bogota, Colombia resulting from a successful public-private partnership. The system comprises specialized infrastructure including [...]
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Integrated traffic grooming in converged data-optical networks
A. Shami, C. Assi, M. Ali, N. Ghani

Collection of open conferences in research transport (2004). Vol. 2004, 68

Abstract
Optical dense wavelength division multiplexing (DWDM) has yielded unprecedented levels of bandwidth scalability. In order to exploit these gains, new converged multiservice transport setups have been evolved, most notably under the multiprotocol label switching (MPLS) and generalized MPLS (GMPLS) frameworks. These paradigms offer very efficient data-optical integration and enable a host of new service capabilities. As operators deploy these new technologies, the provisioning of "subwavelength" demands over wavelengths has become a crucial requirement, i.e., traffic engineering/grooming. This work addresses data-optical grooming in converged GMPLS networks. Here, novel integrated constraint-based routing algorithms are developed to provision subwavelength demands at both packet-switching and lightpath routing levels. Simulations indicate notable performance gains and resource efficiencies with the proposed schemes.
Abstract
Optical dense wavelength division multiplexing (DWDM) has yielded unprecedented levels of bandwidth scalability. In order to exploit these gains, new converged multiservice [...]
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Restorability versus efficiency in (1 : 1)(n) protection schemes for optical networks
D. Griffith, S. Lee, . , K. Sriram, S. Klink, N. Golmie

Collection of open conferences in research transport (2004). Vol. 2004, 67

Abstract
network utilization continues to grow in the coming years, there will be increased pressure on network operators to use traffic engineering to provision resources more efficiently. One way to do this is to allow backup paths associated with disjoint working paths to share bandwidth. Increasing the amount of sharing will naturally increase the risk that a faded working path will either be unrecovered or forced to use dynamic recovery mechanisms. To examine the tradeoffs between robustness and efficiency and to develop useful performance bounds, we develop theoretical models for (1:1)(n) recovery schemes that are independent of the network's topology and management plane. We confirm our results using simulations of uncorrelated failures in a wide-area optical network with various degrees of resource sharing.
Abstract
network utilization continues to grow in the coming years, there will be increased pressure on network operators to use traffic engineering to provision resources more efficiently. [...]
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Service Differentiation over GMPLS
F. Krief, H. Moungla

Collection of open conferences in research transport (2004). Vol. 2004, 65

Abstract
This paper presents the service differentiation over Generalized Multi-Protocol Label Switching (GMPLS) networks. A method is proposed to provide necessary bridges between DiffServ and GMPLS network. Policy framework defined by the IETF is also extended with new policies for controlling and managing the life-cycle of Label Switched Paths (LSPs) and for the mapping of DiffServ traffic onto existing LSPs.
Abstract
This paper presents the service differentiation over Generalized Multi-Protocol Label Switching (GMPLS) networks. A method is proposed to provide necessary bridges between [...]
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Corrosion-Erosion Fatigue of Pipeline Tubes
L. Sosnovskiy, A. Kostyuchenko, A. Bordovsky, V. Vorobyev

Collection of open conferences in research transport (2005). Vol. 2005, 90

Abstract
Reliability and durability of pipeline tubes are mainly affected by repeated alternative pressure, the processes of corrosion and erosion. These phenomena cause degradation of material on the internal surface of the tube. However the traditional methods (experimental and theoretical) of investigation of such damage processes are developed as if these processes acted separately, independently from each other. There are some works in which the joint effect of two phenomena is observed: corrosion-mechanical fatigue and erosive corrosion (or corrosive erosion). Meanwhile in reality the processes of mechanical fatigue, corrosion and hydro erosion act simultaneously and develop in the same part of the tube.Copyright © 2005 by ASME
Abstract
Reliability and durability of pipeline tubes are mainly affected by repeated alternative pressure, the processes of corrosion and erosion. These phenomena cause degradation [...]
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A New Type of Tapered Steel Pipe Pile for Transportation Applications
A. Burns, S. Merjan, J. Horvath, T. Trochalides

Collection of open conferences in research transport (2004). Vol. 2004, 63

Abstract
Piles with a variable perimeter over all or part of their length are generically called tapered piles. The benefit of using tapered piles when axial- compressive loads predominate, especially in 'friction' situations involving coarse- grain soils, has been recognized in principle for a long time. However, this benefit does not appear to have been fully exploited in practice, especially in transportation applications. Several recent events have produced a rebirth of interest in tapered piles, at least in U.S. practice. One was the development and commercial introduction of a new type of proprietary tapered steel pipe pile called the Tapertube. It was developed primarily to provide commercial competition to the long-established Monotube pile but it has also demonstrated that it is a structurally robust pile capable of withstanding the stresses of today's high-capacity design requirements. Of relevance to this conference is that Tapertube piles were essentially developed for, and eventually used extensively on, one of the larger transportation-related projects in the New York City metropolitan area in recent years, the major renovation and expansion work at the John F. Kennedy International Airport. This work included both terminal buildings and several kilometres of elevated light-rail structures as well as project-wide design for seismic loading. As a result, a comprehensive pile-load-test program was conducted to verify the performance of Tapertube piles under compressive, uplift and lateral loads.
Abstract
Piles with a variable perimeter over all or part of their length are generically called tapered piles. The benefit of using tapered piles when axial- compressive loads predominate, [...]
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Communications, navigation and surveillance for improved oceanic air traffic operations
B. Welch, R. Kerczewski, I. Greenfeld

Collection of open conferences in research transport (2005). Vol. 2005, 80

Abstract
traffic management around the world is implemented using ground-based communications, navigation and surveillance systems. For obvious reasons, such systems are not available in oceanic airspace, nor are they available in remote land regions. In general, aircraft operating in these regions maintain safe separations by relying on procedural separation methods. Such methods require separations of 50 nautical miles (nm) or more to be maintained. As air traffic across the oceans increases, the procedural separations are leading to increased inefficiencies in oceanic and remote operations. These inefficiencies result from schedule delays, inability to fly preferred routes (for best wind advantages), and the inability to use the most efficient altitudes, leading to higher fuel burn rates. New methods of operating in oceanic and remote airspace are needed, and indeed they are being developed and implemented, but they depend on an improved communications, navigation and surveillance (CNS) systems, which of necessity must be primarily supplied by satellite-based systems. This paper summarizes current and future air traffic management operations, the CNS requirements for future operations and satellite-based systems which have the potential for fulfilling these requirements, and what is needed to bring such system to implementation
Abstract
traffic management around the world is implemented using ground-based communications, navigation and surveillance systems. For obvious reasons, such systems are not available [...]
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MPLS Based Best Effort Traffic Engineering
H. Owen, J. Rojanarowan, B. Koehler

Collection of open conferences in research transport (2004). Vol. 2004, 61

Abstract
The advent of Multi-protocol Label Switching (MPLS) enables traffic engineering by introducing connection-oriented features of forwarding packets over arbitrary non-shortest paths. Our goal in this research is to improve the network utilization for best effort traffic in IP networks. By examining the best effort traffic class, we assume The large volume of research that has been conducted on traffic engineering for assured forwarding and expedited forwarding with admission control allows traffic engineering on those traffic classes. We examine a different and in some sense a "more complex" problem (traffic demands are not known a priori) of traffic engineering for the remaining network bandwidth which is utilized by best effort traffic. We present a generic traffic engineering framework and four specific algorithms. This framework has two prominent features 1) it uses MPLS to encapsulate source-destination aggregate flows within a Label Switched Path (LSP), with multiple LSPs per source-destination. 2) The framework is "stateless", only the topology is used to determine the traffic routing.
Abstract
The advent of Multi-protocol Label Switching (MPLS) enables traffic engineering by introducing connection-oriented features of forwarding packets over arbitrary non-shortest [...]
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Traffic congestion estimation using HMM models without vehicle tracking
F. Porikli, X. Li

Collection of open conferences in research transport (2004). Vol. 2004, 59

Abstract
We propose an unsupervised, low-latency traffic congestion estimation algorithm that operates on the MPEG video data. We extract congestion features directly in the compressed domain, and employ Gaussian Mixture Hidden Markov Models (GM-HMM) to detect traffic condition. First, we construct a multi-dimensional feature vector from the parsed DCT coefficients and motion vectors. Then, we train a set of left-to-right HMM chains corresponding to five traffic patterns (empty, open flow, mild congestion, heavy congestion, and stopped), and use a Maximum Likelihood (ML) criterion to determine the state from the outputs of the separate HMM chains. We calculate a confidence score to assess the reliability of the detection results. The proposed method is computationally efficient and modular. Our tests prove that the feature vector is invariant to different illumination conditions, e.g., sunny, cloudy, dark. Furthermore, we do not need to impose different models for different camera setups, thus we significantly reduce the system initialization workload and improve its adaptability. Experimental results show that the precision rate of the presented algorithm is very high- around 95%.
Abstract
We propose an unsupervised, low-latency traffic congestion estimation algorithm that operates on the MPEG video data. We extract congestion features directly in the compressed [...]
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Systematic register bypass customization for application-specific processors
K. Fan, K. Manjunath, M. Smelyanskiy, M. Chu, S. Mahlke, R. Ravindran, N. Clark

Collection of open conferences in research transport (2004). Vol. 2004, 58

Abstract
Register bypass provides additional datapaths to eliminate data hazards in processor pipelines. The difficulty with register bypass is that the cost of the bypass network is substantial and grows substantially as processor width or pipeline depth are increased. For a single application, many of the bypass paths have extremely low utilization. Thus, there is an important opportunity in the design of application-specific processors to remove a large fraction of the bypass cost while maintaining performance comparable to a processor with full bypass. We propose a systematic design customization process along with a bypass-cognizant compiler scheduler. For the former, we employ iterative design space exploration wherein successive processor designs are selected based on bypass utilization statistics combined with the availability of redundant bypass paths. Compiler scheduling for sparse bypass processors is accomplished by prioritizing function unit choices for each operation prior to scheduling using global information. Results show that for a 5-issue customized VLIW processor, 70% of the bypass cost is eliminated while sacrificing only 10% performance.
Abstract
Register bypass provides additional datapaths to eliminate data hazards in processor pipelines. The difficulty with register bypass is that the cost of the bypass network [...]
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Testing the detection pipelines for inspirals with Virgo commissioning run C4 data
R. Gouaty, L. Fiore, C. Boccara, S. Pardi, S. Aoudia, R. Passaquieti, C. Palomba, D. Passuello, S. Solimeno, N. Morgado, S. Frasca, I. Fiori, J. Fournier, A. Brillet, C. Corda, A. Eleuteri, I. Ferrante, M. Loupias, A. Viceré, R. Poggiani, L. Giordano, G. Russo, L. Milano, J. Vinet, R. Cavalieri, L. Pinard, M. Mazzoni, A. Giazotto, P. Puppo, G. Cella, C. Man, F. Cavalier, R. Taddei, B. Dujardin, V. Dattilo, G. Guidi, V. Brisson, P. Rapagnani, M. Mantovani, V. Reita, L. Gammaitoni, J. Marque, D. Grosjean, G. Losurdo, M. Tonelli, A. Virgilio, M. Barsuglia, B. Bizouard, F. Bondu, K. Qipiani, F. Travasso, M. Alshourbagy, F. Fidecaro, F. Marion, F. Piergiovanni, C. Bradaschia, F. Marchesoni, P. Hello, D. Verkindt, S. Avino, V. Loriette, A. Gennai, F. Ricci, G. Vajente, L. Bosi, F. Cleva, F. Vetrano, R. Stanga, P. Penna, B. Mours, F. Acernese, M. Yvert, M. Davier, A. Spallicci, R. Barille, A. Clapson, D. Buskulic, H. Heitmann, E. Chassande-Mottin, L. Holloway, F. Martelli, C. Moins, Z. Zhang, A. Toncelli, S. Hebri, A. Remillieux, F. Beauville, J. Moreau, E. Majorana, L. Brocco, S. Braccini, G. Giordano, E. Campagna, I. Ricciardi, M. Punturo, E. Tournefier, R. Flaminio, L. Barsotti, D. Tombolato, A. Pai, D. Babusci, F. Paoletti, F. Barone, A. Masserot, G. Ballardin, P. Amico, A. Freise, D. Enard, J. Mackowski, P. Ruggi, R. Rosa, S. Kreckelbergh, B. Perniola, E. Calloni, J. Coulon, H. Vocca, F. Frasconi, A. Pasqualetti, E. Cuoco

Collection of open conferences in research transport (2004). Vol. 2004, 57

Abstract
We report on an investigation of Virgo Commissioning run 4 data, dedicated to searching signals of the kind supposed to be emitted by inspiral neutron star binary systems. Given the still relatively limited sensitivity, the goal was to test some of the elements of the analysis chain, using simulated events, hardware and software injected in the data; the test allowed us to also characterize the detector stability during the run, for the purposes of the inspiral event search.
Abstract
We report on an investigation of Virgo Commissioning run 4 data, dedicated to searching signals of the kind supposed to be emitted by inspiral neutron star binary systems. [...]
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Agent Architecture for Aviation Data Integration System
M. Windrem, D. Kulkarni, H. Patel, Y. Wang, M. Wei

Collection of open conferences in research transport (2004). Vol. 2004, 56

Abstract
This paper describes the proposed agent-based architecture of the Aviation Data Integration System (ADIS). ADIS is a software system that provides integrated heterogeneous data to support aviation problem-solving activities. Examples of aviation problem-solving activities include engineering troubleshooting, incident and accident investigation, routine flight operations monitoring, safety assessment, maintenance procedure debugging, and training assessment. A wide variety of information is typically referenced when engaging in these activities. Some of this information includes flight recorder data, Automatic Terminal Information Service (ATIS) reports, Jeppesen charts, weather data, air traffic control information, safety reports, and runway visual range data. Such wide-ranging information cannot be found in any single unified information source. Therefore, this information must be actively collected, assembled, and presented in a manner that supports the users problem-solving activities. This information integration task is non-trivial and presents a variety of technical challenges. ADIS has been developed to do this task and it permits integration of weather, RVR, radar data, and Jeppesen charts with flight data. ADIS has been implemented and used by several airlines FOQA teams. The initial feedback from airlines is that such a system is very useful in FOQA analysis. Based on the feedback from the initial deployment, we are developing a new version of the system that would make further progress in achieving following goals of our project.
Abstract
This paper describes the proposed agent-based architecture of the Aviation Data Integration System (ADIS). ADIS is a software system that provides integrated heterogeneous [...]
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A Label space reduction algorithm for P2MP LSPs using asymmetric tunnels
R. Fabregat, F. Solano, J. Marzo, Y. Donoso

Collection of open conferences in research transport (2005). Vol. 2005, 68

Abstract
The aim of traffic engineering is to optimise network resource utilization. Although several works on minimizing network resource utilization have been published, few works have focused on LSR label space. This paper proposes an algorithm that uses MPLS label stack features in order to reduce the number of labels used in LSPs forwarding. Some tunnelling methods and their MPLS implementation drawbacks are also discussed. The algorithm described sets up the NHLFE tables in each LSR, creating asymmetric tunnels when possible. Experimental results show that the algorithm achieves a large reduction factor in the label space. The work presented here applies for both types of connections: P2MP and P2P.
Abstract
The aim of traffic engineering is to optimise network resource utilization. Although several works on minimizing network resource utilization have been published, few works [...]
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Technical-Economical Feasibility of Using Centrifugal Pumps in High-Density Thickened Tailings Slurry Systems
L. Whitlock, G. Addie, A. Sellgren

Collection of open conferences in research transport (2005). Vol. 2005, 67

Abstract
Pumping simulated tailings slurry at a high solids content has been investigated at the GIW Hydraulic Testing Laboratory in a 0.075 m diameter loop with a centrifugal pump with an auger-like inducer. The results and earlier experiences from the Laboratory and some reported data indicate that viscous slurries characterized by shear stresses in pipeline transportation of 100 to 200 Pa can be pumped effectively with centrifugal pumps. Stresses in this range were reported in pipeline, flume and viscometer experiments with typical base metal tailings slurries at concentrations by volume of 44% in pilot-scale thickening tests. The corresponding concentration by mass,70%, gave a non-segregating mixture which could be disposed at slopes of about 4%. With this type of slurry, an overall economical comparison here indicates that centrifugal pumps are a cost-effective alternative also in high pressure applications (4 MPa) corresponding to a distance of 1000 m when pumping 300 tonnes per hour. Pumping simulated tailings slurry at a high solids content has been investigated at the GIW Hydraulic Testing Laboratory in a 0.075 m diameter loop with a centrifugal pump with an auger-like inducer. The results and earlier experiences from the Laboratory and some reported data indicate that viscous slurries characterized by shear stresses in pipeline transportation of 100 to 200 Pa can be pumped effectively with centrifugal pumps. Stresses in this range were reported in pipeline, flume and viscometer experiments with typical base metal tailings slurries at concentrations by volume of 44% in pilot-scale thickening tests. The corresponding concentration by mass,70%, gave a non-segregating mixture which could be disposed at slopes of about 4%. With this type of slurry, an overall economical comparison here indicates that centrifugal pumps are a cost-effective alternative also in high pressure applications (4 MPa) corresponding to a distance of 1000 m when pumping 300 tonnes per hour.
Abstract
Pumping simulated tailings slurry at a high solids content has been investigated at the GIW Hydraulic Testing Laboratory in a 0.075 m diameter loop with a centrifugal pump [...]
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Congestion management of self similar IP traffic using probability based normal and exponential marking RED
O. Gol, S. Suresh

Collection of open conferences in research transport (2005). Vol. 2005, 63

Abstract
Schemes described in the literature on network congestion management are in general based on queue management. Also it is widely accepted that Poisson model is not sufficient to characterize the traffic in current Internet. In this paper, we present the details of some simulation studies carried out on an alternate RED (random early detection) algorithm for traffic congestion management in IP networks having self similar input. We first discuss the basic scheme of normal as proposed by Floyd et al., for the Poisson input model, and then explain a new AQM proposed by us. Our modification to the RED algorithm takes into consideration probability values corresponding to the average queue lengths for computing the marking/dropping probability. Verification of the algorithms proposed vis-a-vis that of Floyd as well as the ones proposed by us, has been done by simulating self-similar traffic. Results of the verification have been discussed in the paper
Abstract
Schemes described in the literature on network congestion management are in general based on queue management. Also it is widely accepted that Poisson model is not sufficient [...]
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Reducing the Environmental Impact of Quayside Cranes on Neighboring Communities
M. Sisson, C. Morris, A. Bhimani

Collection of open conferences in research transport (2004). Vol. 2004, 54

Abstract
The continuing growth of marine container terminals is causing increasing environmental concerns among neighboring communities. The increasing container volumes have resulted in increased truck traffic and larger and faster container handling equipment. The higher truck traffic has raised concerns about diesel fumes and traffic congestion. The larger cranes have raised concerns about noise levels and visual impact. The increase in number and size of the cranes and the encroachment of the terminals and the neighboring communities on each other exacerbate the problem. This paper examines the environmental impact of the ever-increasing size of dockside container cranes on neighboring communities and presents potential solutions to reduce the impact. The paper focuses on reducing the noise levels generated by the crane operations and reducing the visual impact of the large cranes. The paper also presents case studies demonstrating designs that reduce the noise levels and visual impact of large cranes. The noise reduction technology was recently applied to new cranes in Amsterdam and other European ports. The visual impact of large cranes is currently being studied at the Port of Los Angeles. The Port of Los Angeles study also demonstrates how high level graphics is used to communicate the impact of the large cranes.
Abstract
The continuing growth of marine container terminals is causing increasing environmental concerns among neighboring communities. The increasing container volumes have resulted [...]
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A novel Markov model for the reliability prediction of fault tolerant non-homogenous multipipelines
H. Al-Asaad

Collection of open conferences in research transport (2004). Vol. 2004, 53

Abstract
novel Markov model for the reliability prediction of fault-tolerant non-homogenous VLSI and WSI multipipeline arrays is presented. The PEs (processing elements) of the array are assumed to fail independently (with a constant failure rate) at different moments and the transition rate between two different error states is constant. A total system failure is reached when the number of working pipelines becomes less than a predetermined number S/sub m/. Thus the reliability of the multipipeline array is defined as the probability of having S(t) greater than or equal to S, where S(t) is the number of survived pipelines at time t, and S/sub m/ is the minimum number of survived pipelines that is needed for the multipipeline to be considered in a working condition. In addition to predicting the reliability, the Markov model can be used in design optimization to determine the best possible design among multiple alternatives. Several experiments are conducted that demonstrate the ability of the proposed Markov model to predict the reliability and to evaluate various design alternatives.
Abstract
novel Markov model for the reliability prediction of fault-tolerant non-homogenous VLSI and WSI multipipeline arrays is presented. The PEs (processing elements) of the array [...]
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Prospective Unmanned Aerial Vehicle Operations in the Future National Airspace System
M. DeGarmo, G. Nelson

Collection of open conferences in research transport (2004). Vol. 2004, 52

Abstract
The Unmanned Aerial Vehicle (UAV) market is expected to grow dramatically by 2020, as military, civil and commercial applications continue to develop. The National Airspace System (NAS) is also expected to change significantly over the next 16 years, with the introduction of new technologies and procedures. Potential changes include the creation of an information management system to exchange information among Air Traffic Management users and providers, the introduction of 4-D navigation, and the development of alternative separation procedures. This paper compares prospective UAV applications against underlying assumptions of the future NAS. Seven UAV operational scenarios that describe how UAVs may operate in the future NAS are presented. The impact of each scenario on the future NAS is summarized, and associated issues identified. The paper concludes by describing the need for a UAV roadmap to the future, which would identify the critical steps required to ensure UAVs are fully integrated into the future NAS.
Abstract
The Unmanned Aerial Vehicle (UAV) market is expected to grow dramatically by 2020, as military, civil and commercial applications continue to develop. The National Airspace [...]
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The limits of speculative trace reuse on deeply pipelined processors
A. Costa, P. Navaux, M. Soffa, F. França, B. Childers, M. Pilla

Collection of open conferences in research transport (2004). Vol. 2004, 51

Abstract
Trace reuse improves the performance of processors by skipping the execution of sequences of redundant instructions. However, many reusable traces do not have all of their inputs ready by the time the reuse test is done. For these cases, we developed a new technique called reuse through speculation on traces (RST), where trace inputs may be predicted. We study the limits of RST for modern processors with deep pipelines, as well as the effects of constraining resources on performance. We show that our approach reuses more traces than the nonspeculative trace reuse technique, with speedups of 43% over a nonspeculative trace reuse and 57% when memory accesses are reused.
Abstract
Trace reuse improves the performance of processors by skipping the execution of sequences of redundant instructions. However, many reusable traces do not have all of their [...]
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Congestion management of IP traffic using adaptive exponential RED
S. Suresh, Ö. Göl

Collection of open conferences in research transport (2005). Vol. 2005, 57

Abstract
In an IP network, if the source rates are increased beyond the service rates of the routers, then queues of packets waiting to be routed at the buffers, build up and exceed the buffering capacity of these routers leading to packets getting dropped. This results in low throughput and congestion collapse. In such networks, an AQM mechanism manages queue lengths in buffers and enables the end-systems to react to such losses by reducing their packet rate, avoiding severe congestion. Random Early Detection (RED) is one of the first AQM mechanisms to be used to avoid congestion in this manner. In this paper, the existing Normal and Gentle RED algorithms of Floyd as well as the justification for the proposed modified exponential RED algorithm have been discussed along with the results obtained on the functioning of the algorithms. Functioning of the algorithm proposed has also been tested using ns2 Simulator.
Abstract
In an IP network, if the source rates are increased beyond the service rates of the routers, then queues of packets waiting to be routed at the buffers, build up and exceed [...]
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Modeling Leakage in a Fuel Transfer Pipeline Using Computational Fluid Dynamics Techniques
H. Pordal, C. Alexander

Collection of open conferences in research transport (2005). Vol. 2005, 55

Abstract
Stress Engineering Services, Inc. (SES) performed an assessment of leaks for an insurance company that occurred in a fuel transfer pipeline at a tank storage facility. Of specific interest were the duration and timing of the leaks, which occurred from a 30 foot section that entered an earthen containment berm. It was originally estimated that 28,900 gallons of gasoline and ethanol leaked periodically from two (2) pin holes in the pipeline during a two month period. Early analysis efforts were not able to estimate the conditions that were necessary to cause the leaking fluid to break through the surface of the earthen berm (a phenomenon known as daylighting). Consequently, SES performed a more rigorous investigation to determine what conditions were required to produce daylighting, the significance of which involved quantifying the estimates of leak duration and the petroleum volumes. This effort integrated assumptions and data from prior analyses to assess the effects of time-dependency using computational fluid dynamics (CFD) modeling techniques. The intent was to take the existing calculations and provide a more technically-defensible model to predict the timing and volume released using reasonable conditions. SES used soil permeability and actual pipe pressure data to simulate the pipeline leak and soil conditions. The results of the CFD analysis showed that it is possible for daylighting to occur within a two-month period. However, a specific combination of conditions associated with leak rates, leak duration, and soil permeability are required to generate daylighting in a relatively short period of time. The predominant observation is that there must be extended periods of continuous leaking involving leak rates of sufficient magnitude. The significance of this work is that it presents a proven analytical method for modeling leaks in pipelines and addressing the effects of specific variables on the amount of released products and the time required to achieve specific leak volumes.Copyright © 2005 by ASME
Abstract
Stress Engineering Services, Inc. (SES) performed an assessment of leaks for an insurance company that occurred in a fuel transfer pipeline at a tank storage facility. Of [...]
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Cryogenic Chilldown Model for Stratified Flow Inside a Pipe
J. Chung, K. Yuan, J. Liao, R. Mei, J. Klausner

Collection of open conferences in research transport (2005). Vol. 2005, 53

Abstract
pseudo-steady model has been developed to predict the chilldown history of the pipe wall temperature in horizontal transport pipelines for cryogenic fluids. A new film boiling heat transfer model is developed by incorporating the stratified flow structure for cryogenic chilldown. A modified nucleate boiling heat transfer correlation for the cryogenic chilldown process inside a horizontal pipe is proposed. The efficacy of the correlations is assessed by comparing the model predictions with measured values of wall temperature in several azimuthal positions in a well controlled experiment by Chung et al. (2004). The computed pipe wall temperature histories match well with the measured results. The present model captures important features of thermal interaction between the pipe wall and the cryogenic fluid, provides a simple and robust platform for predicting the pipe wall chilldown history in a long horizontal pipe at relatively low computational cost, and builds a foundation to incorporate the two-phase hydrodynamic interaction in the chilldown process.Copyright © 2005 by ASME
Abstract
pseudo-steady model has been developed to predict the chilldown history of the pipe wall temperature in horizontal transport pipelines for cryogenic fluids. A new film boiling [...]
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Enabling air-ground integration: concept definition for traffic information service in contract mode (TIS-C)
R. Ehrmanntraut

Collection of open conferences in research transport (2004). Vol. 2004, 48

Abstract
The goal of this paper is to introduce the new TIS-C concept, and to give a high-level definition as well as to discuss its performance parameters. It was shown in the study "alternative enablers for airborne separation assistance systems (ASAS)" according to R. Ehrmanntraut (2002) that traffic information service in contract mode (TIS-C) when compared with its broadcast counterpart TIS-B is a better candidate to support ASAS applications. That viewpoint was systematically developed, and a high number of arguments were developed to give evidence. Based on these findings it would be useful to give a better definition of the new TS-C concept. The objective of TIS-C is to provide the flight deck with many kinds of traffic related information, using point-to-point telecommunications. The traffic information may be manifold and concern the ownship as well as its surroundings. The entire scope of the concept is described by indicating the variety of possible information that can be presented in the flight deck, from the simple positions of other aircraft, to flight vectors, flight plans, trajectories, to airspace information and airport information. Then some of the basic data used in TIS-C: position, flight plan, trajectory, and medium-term conflict is described. The highest-level use cases of TIS-C are defined. A first draft of the protocols between the TIS consumer and provider is given: a total information sharing protocol. The architecture of TIS-C is described and its sub-enablers are discussed. Finally there is a conclusion with a number of steps to take f the TIS-C concept is to be brought towards implementation and an extrapolation of future applications is given that could be provided with TIS-C.
Abstract
The goal of this paper is to introduce the new TIS-C concept, and to give a high-level definition as well as to discuss its performance parameters. It was shown in the study [...]
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Cost efficient overflow routing for outbound ISP traffic
R. Harris, A. Kist

Collection of open conferences in research transport (2004). Vol. 2004, 47

Abstract
Multihomed Internet service providers (ISPs) are typically connected to several transit ISPs. If cost is assigned to interconnecting resources, multihomed ISPs face the problem of cost efficient outbound traffic routing. In particular, this is relevant if the ISPs form customer to provider relationships and alternative billing schemes are used, i.e. volume or time based. The border gateway protocol (BGP) is the de facto standard for inter-domain IP routing on the Internet but its traffic engineering capabilities are limited. This paper proposes a local overflow methodology that allows cost efficient outbound packet routing and is based on the scheme for alternative packet overflow routing (SAPOR). The paper identifies the underlying optimisation problem, introduces the modified SAPOR methodology and presents simulation results that verify the operation of the scheme.
Abstract
Multihomed Internet service providers (ISPs) are typically connected to several transit ISPs. If cost is assigned to interconnecting resources, multihomed ISPs face the problem [...]
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A new flight guidance approach based on differential flatness
W. Lu, F. Mora-Camino, K. Achaibou

Collection of open conferences in research transport (2004). Vol. 2004, 46

Abstract
International audience; With the sustained increase of air traffic, the demand for new maneuvering capabilities of transport aircrafts is getting more important in order to tackle traffic saturated conditions. In this communication, a new guidance control structure is proposed to perform trajectory tracking through smooth manoeuvers. The design approach is based first on a differential flatness property of aircraft guidance dynamics which is displayed in This work and then on the use of neural networks to invert the guidance dynamics in order to generate directives to the autopilot. To compensate the effect of modeling errors and of other disturbances, an adaptive control approach is adopted to perform the maneuvers.
Abstract
International audience; With the sustained increase of air traffic, the demand for new maneuvering capabilities of transport aircrafts is getting more important in order to [...]
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Improving the quality and reliability of traffic differentiation in IP networks
P. Carvalho, V. Freitas, P. Sousa

Collection of open conferences in research transport (2004). Vol. 2004, 45

Abstract
This article presents a modular scheduling architecture for multi-QoS metric differentiation in class-based IP networks. The rationale of the supported differentiation modules is presented, highlighting the distinct differentiation semantics that might be used to control the delay, loss and rate metrics associated with the traffic classes. The devised modules resort to several relative and hybrid differentiation models to bound QoS metrics on high priority classes. In the proposed scheduling architecture, the differentiation modules may act jointly in order to control simultaneously multiple QoS metrics. The results show that using simple and intuitive configuration procedures the proposed architecture is able to provide enhanced QoS differentiation behavior in IP networks according to the users and applications needs.
Abstract
This article presents a modular scheduling architecture for multi-QoS metric differentiation in class-based IP networks. The rationale of the supported differentiation modules [...]
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A continuous network design model in stochastic user equilibrium based on sensitivity analysis
S. Lee, Y. Lim, B. Heydecker

Collection of open conferences in research transport (2005). Vol. 2005, 47

Abstract
The continuous network design problem (CNDP) is known to be difficult to solve due to the intrinsic properties of non-convexity and nonlinearity. Such kinds of CNDP can be formulated as a bi-level programme, in which the upper level represents the designer's decisions and the lower level the travellers' responses. Formulations of this kind can be classified as either Stackelberg approaches or Nash ones according to the relationship between the upper level and the lower level parts. This paper formulates the CNDP for road expansion based on Stackelberg game where leader and follower exist, and allows for variety of travellers' behaviour in choosing their routes. In order to solve the problem by the Stackelberg approach, we need a relation between link flows and design parameters. For this purpose, we use a logit route choice model, which provides this in an explicit closed-form function. This model is applied to two example road networks to test and briefly compare the results between the Stackelberg and Nash approaches to explore the differences between them.
Abstract
The continuous network design problem (CNDP) is known to be difficult to solve due to the intrinsic properties of non-convexity and nonlinearity. Such kinds of CNDP can be [...]
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Improvement of the driving safety using a virtual driver
R. Siegwart, H. Bubb, F. Holzmann

Collection of open conferences in research transport (2005). Vol. 2005, 41

Abstract
This paper introduces a new concept for advanced driver assistance by means of a defined architecture including all system components redundant from the environment perception to the vehicle controllers. The first part analyzes the bottleneck of the current association driver with vehicle. After that a virtual driver, which computes the safety envelope of the motion vector of the vehicle, would be described. The driver's command would be monitored depending on the output of this virtual driver to give a feedback to the driver or to take the control of the vehicle. In the next part a concept of exchange of information to enhance the cognition of the vehicle and of the driver would be explained. At the end this paper would conclude towards future works and research issues.
Abstract
This paper introduces a new concept for advanced driver assistance by means of a defined architecture including all system components redundant from the environment perception [...]
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Techniques for energy minimization of communication pipelines
M. Potkonjak, G. Qu

Collection of open conferences in research transport (2004). Vol. 2004, 41

Abstract
The performance of many modern computer and communication systems is dictated by latency of communication pipelines. At the same time, power consumption is often another limiting factor in many portable systems. We address the problem of how to minimize the power consumption in system level pipelines under latency constraints. In particular, we exploit advantages provided by variable voltage design methodology to optimally select speed and therefore voltage of each pipeline stage. We define the problem and solve it optimally under realistic and widely accepted assumptions. We apply the obtained theoretical results to develop algorithms for power minimization of computer and communication systems and show that significant power reduction is possible without additional latency.
Abstract
The performance of many modern computer and communication systems is dictated by latency of communication pipelines. At the same time, power consumption is often another limiting [...]
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Classification and Evaluation of Constraint-Based Routing Algorithms for MPLS Traffic Engineering
S. Lahoud, G. Texier, L. Toutain

Collection of open conferences in research transport (2004). Vol. 2004, 40

Abstract
National audience; Multiprotocol Label Switching (MPLS) is experiencing a growing interest mainly due to the flexible support of traffic engineering and Quality of Service (QoS). The efficient routing of Label Switched Paths (LSP) is an active research field where Constraint-Based Routing (CBR) appears to be a major building block. CBR can be seen as the decision entity that calculates the explicit paths for LSPs. The path calculation process can be constrained by different criteria, such as QoS requirements and particularly bandwidth guarantees considered in this paper. Special attention has been given to on-line solutions for CBR that process LSP establishment demands on the fly without any information on future demands. Currently, many proposals are formulated for CBR algorithms for bandwidth guaranteed tunnels, often compared to prove the effectiveness of one method over another. Nevertheless, no coherent evaluation has been clearly established for the general CBR problem, pointing out the different trade-offs involved in many solutions. In this article, we investigate the different objectives of CBR algorithms. We establish clear and general criteria for these algorithms, namely: reducing blocking probability, minimizing network costs, and load balancing. An effort of classification is made in order to map existing proposals to the proposed criteria. The study, performed to evaluate the influence of these parameters with simulations, shows the drawbacks of partial considerations, and the need for a global solution. Finally, we propose an integrating solution that encompasses the different criteria presented in the paper.
Abstract
National audience; Multiprotocol Label Switching (MPLS) is experiencing a growing interest mainly due to the flexible support of traffic engineering and Quality of Service [...]
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Test and Integration of a Detect and Avoid System
J. McCalmont, J. Utt, W. Afb

Collection of open conferences in research transport (2004). Vol. 2004, 38

Abstract
Remotely Operated Aircraft (ROAs) currently do not have convenient access to civil airspace due to their inability to provide an onboard capability to “see and avoid” air traffic. Defense Research Associates, Inc. and AFRL/SNJT have developed affordable technology based on silicon charge couple device sensors and passive moving target detection algorithms. Previously, an all-software implementation of the algorithms demonstrated concept feasibility by using video data recorded during flight testing. This paper documents subsequent implementation and field testing of a real-time version of the system with field programmable gate arrays handling the detection processing and multiple sensors to demonstrate the wide field of regard required. The implementation met demonstration goals by functioning reliably in real-time and providing detection and false detection performance comparable to that of the previous, non-real-time version.
Abstract
Remotely Operated Aircraft (ROAs) currently do not have convenient access to civil airspace due to their inability to provide an onboard capability to “see and avoid” [...]
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Trafficview: a scalable traffic monitoring system
S. Dashtinezhad, C. Liao, L. Iftode, T. Nadeem

Collection of open conferences in research transport (2004). Vol. 2004, 37

Abstract
Vehicles are part of people's life in modern society, into which more and more high-tech devices are integrated, and a common platform for inter-vehicle communication is necessary to realize an intelligent transportation system supporting safe driving, dynamic route scheduling, emergency message dissemination, and traffic condition monitoring. TrafficView, which is a part of the e-Road project, defines a framework to disseminate and gather information about the vehicles on the road. Using such a system will provide a vehicle driver with road traffic information, which helps driving in situations such as foggy weather, or finding an optimal route in a trip several miles long. This paper describes the basic design of TrafficView and different algorithms used in the system.
Abstract
Vehicles are part of people's life in modern society, into which more and more high-tech devices are integrated, and a common platform for inter-vehicle communication is necessary [...]
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The Data Reduction and Analysis Graphical Organizer
M. Scodeggio, P. Franzetti, L. Paioro, B. Garilli

Collection of open conferences in research transport (2004). Vol. 2004, 36

Abstract
Spectroscopic surveys are undergoing a rapid expansion in their data collecting capabilities, reaching the level of hundreds of spectra per pointing. An efficient use of such huge amounts of information requires a high degree of interconnection between the various tools involved in preparing the observations, reducing the data, and carrying out the data analysis. DRAGO (Data Reduction and Analysis Graphical Organizer) attempts to easy the process, by integrating in a global framework the main data handling components: from reduction pipelines, to data organization, plotting, and browsing tools, to storing the data reduction results in a database for further analysis. DRAGO allows the use of the astronomer own's preferred tools, by "plugging them in" in an environment which handles transparently the communications between them. See http://cosmos.mi.iasf.cnr.it/pandora. Document type: Conference object
Abstract
Spectroscopic surveys are undergoing a rapid expansion in their data collecting capabilities, reaching the level of hundreds of spectra per pointing. An efficient use of such [...]
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Air Traffic Conflict Models
M. Jardin

Collection of open conferences in research transport (2004). Vol. 2004, 35

Abstract
Semi-empirical random variable models of the expected number of air traffic conflicts as a function of air traffic density are derived. Model parameters are determined from analysis and simulation of real air traffic data. These models are applied to simulated air traffic scenarios to analyze conflict properties in various conflict resolution strategies. It is shown that under free routing conditions (i.e. aircraft do not necessarily fly along structured jet routes), the expected number of conflicts is well represented by a binomial random variable model. Using this model, it is further demonstrated how conflict resolution may cause a chain reaction, leading to an increased number of conflicts for all aircraft, and how the model may be used to predict the airspace capacity for a given conflict resolution strategy. In a separate study, it is shown that for an iterative horizontal-plane conflict resolution strategy, a random variable model with the geometric distribution closely matches empirical data. This model also predicts the aircraft density at which the airspace becomes saturated. It is shown how analysis of conflicts in the horizontal plane may be scaled and applied to the analysis of conflicts in 3-dimensional airspace. In this paper, probabilistic models of air traffic conflict situations are derived and analyzed to gain physical insight into the relationship between increasing air traffic density and the expected number of conflicts between aircraft. The first section examines the expected number of conflicts under both a structured routing system and under a free routing system. It is shown that a binomial random variable model closely matches observations of the number of conflicts when conflict resolution is not applied. The effect of conflict resolution maneuvering on the expected number of conflicts is also examined. An analytical model is derived, and simulation results are used to verify the model. The second main section of this paper introduces a model of the expected number of conflicts when an iterative approach to conflict resolution is taken. This model is examined to show how it may be used to predict maximum airspace capacity.
Abstract
Semi-empirical random variable models of the expected number of air traffic conflicts as a function of air traffic density are derived. Model parameters are determined from [...]
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Scheduling heuristics for on board sequential air conflict solving
N. Durand, N. Archambault

Collection of open conferences in research transport (2004). Vol. 2004, 31

Abstract
International audience; The resolution of conflicts between n aircraft is highly combinational and cannot be optimally solved using classical mathematical optimization techniques. Using a priority order to solve a n-aircraft conflict is much easier but the solution is not optimal. FACES (free-flight autonomous coordinated en route solver) is a model for coordinated on-board sequential conflict solving. In this project, conflict-free trajectories are obtained by applying elementary maneuvers to each aircraft, sequentially, according to some priority order. In this paper, a comparative study on a set of proposed priority heuristics to provide a suitable priority order is presented, and aggregated heuristics are compared according to some criteria. The conflict solver FACES using heuristics is tested in en-route upper airspace within an air traffic simulator using real traffic data.
Abstract
International audience; The resolution of conflicts between n aircraft is highly combinational and cannot be optimally solved using classical mathematical optimization techniques. [...]
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Rule Based Congestion Management – Monitoring Self-similar IP Traffic in Diffserv Networks
Ö. Göl, S. Suresh

Collection of open conferences in research transport (2005). Vol. 2005, 25

Abstract
In this paper, we discuss employing a server in a router, the architecture of which is based on policy, for congestion management of IP traffic in Diffserv networks. We exploit the congestion information and employ that information to manipulate the network level parameters to adapt the traffic according to the current congestion state of the network. The congestion monitors interact with the policy server, which, depending on the network state, decides the policy/rules that should be enforced by the Diffserv network. The implementation of the selected policies typically leads to accepting, remarking or dropping the IP traffic packets entering the network. We have also indicated how these modules could functionally be used to generate and store appropriate rules based on policies for congestion management. Since the system will now be rule based, there is a need for policing action to monitor traffic and enforce these rules when congestion sets in, and we propose mobile agents accomplishing this job. Index Terms: Quality of service, IP Networks Congestion Management, Self-similar input, Policy based rules, Mobile Agents.
Abstract
In this paper, we discuss employing a server in a router, the architecture of which is based on policy, for congestion management of IP traffic in Diffserv networks. We exploit [...]
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Redesign of the European route network for sector-less
T. Riviere

Collection of open conferences in research transport (2004). Vol. 2004, 29

Abstract
International audience; The increase in air traffic and the limited capacity of air traffic control services force us to think of a new way in which to control aircraft. An innovative ATM concept, called Sector-Less Air Traffic Management, has been defined by the Eurocontrol Experimental Centre. In this concept the role of the controller is radically different from the current one : instead of having controllers controlling a sector, controllers would be responsible for a certain number of aircraft from departure to arrival in terminal areas. The aim of this paper is to redesign the European en-route network in order to make this new way of controlling aircraft possible and to provide an aeroplane with the shortest route possible by providing a new route network. The approach proposed here is, starting from scratch, to provide a very simple route network and to improve it by using optimisation algorithm. A generated route network will be evaluated in terms of length of trajectories weighted by the amount of aeroplanes using them and then compare it with the direct route network and the current one. Using this tool and a fast time air traffic simulator, the Sector-Less concept will be able to be evaluated in terms of capacity and delay due to conflict. This also provides the route density of the network for this concept. The results of various simulations performed on the best route network generated so far will be presented.
Abstract
International audience; The increase in air traffic and the limited capacity of air traffic control services force us to think of a new way in which to control aircraft. An [...]
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ADS-B within a multi-aircraft simulation for distributed air-ground traffic management
R. Barhydt, M. Palmer, W. Chung, G. Loveness

Collection of open conferences in research transport (2004). Vol. 2004, 28

Abstract
utomatic dependent surveillance broadcast (ADS-B) is an enabling technology for NASA's distributed air-ground traffic management (DAG-TM) concept. DAG-TM has the goal of significantly increasing capacity within the National Airspace System, while maintaining or improving safety. Under DAG-TM, aircraft exchange state and intent information over ADS-B with other aircraft and ground stations. This information supports various surveillance functions including conflict detection and resolution, scheduling, and conformance monitoring. To conduct more rigorous concept feasibility studies, NASA Langley Research Center's PC-based air traffic operations simulation models a 1090 MHz ADS-B communication structure, based on industry standards for message content, range, and reception probability. The current ADS-B model reflects a mature operating environment and message interference effects are limited to Mode S transponder replies and ADS-B squitters. This model was recently evaluated in a joint DAG-TM air/ground coordination experiment with NASA Ames Research Center. Message probability of reception vs. range was lower at higher traffic levels. The highest message collision probability occurred near the meter fix serving as the confluence for two arrival streams. Even the highest traffic level encountered in the experiment was significantly less than the industry standard "LA Basin 2020" scenario. Future studies will account for Mode A and C message interference (a major effect in several industry studies) and will include Mode A and C aircraft in the simulation, thereby increasing the total traffic level. These changes will support ongoing enhancements to separation assurance functions that focus on accommodating longer ADS-B information update intervals.
Abstract
utomatic dependent surveillance broadcast (ADS-B) is an enabling technology for NASA's distributed air-ground traffic management (DAG-TM) concept. DAG-TM has the goal of significantly [...]
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Asymmetric tunnels in P2MP LSPs as a label space reduction method
F. Solano, J. Marzo, R. Fabregat, Y. Donoso

Collection of open conferences in research transport (2005). Vol. 2005, 20

Abstract
The objective of traffic engineering is to optimize network resource utilization. Although several works have been published about minimizing network resource utilization, few works have focused on LSR (label switched router) label space. This paper proposes an algorithm that takes advantage of the MPLS label stack features in order to reduce the number of labels used in LSPs. Some tunnelling methods and their MPLS implementation drawbacks are also discussed. The described algorithm sets up NHLFE (next hop label forwarding entry) tables in each LSR, creating asymmetric tunnels when possible. Experimental results show that the described algorithm achieves a great reduction factor in the label space. The presented works apply for both types of connections: P2MP (point-to-multipoint) and P2P (point-to-point).
Abstract
The objective of traffic engineering is to optimize network resource utilization. Although several works have been published about minimizing network resource utilization, [...]
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Natural Language Processing in the Control of Unmanned Aerial Vehicles
E. Craparo, E. Feron

Collection of open conferences in research transport (2004). Vol. 2004, 27

Abstract
This paper addresses the opportunities and challenges involved in applying natural language processing techniques to the control of unmanned aerial vehicles (UAVs). The problem of controlling an unmanned aircraft via natural language inputs is formulated as a feedback control problem. Two implementations of such systems are described. The phraseology of the existing air traffic control language is used as a base command set, and knowledge of air traffic control and airport operations, combined with existing natural language processing techniques, is used to achieve a higher recognition success rate than a traditional natural language processor designed for a more general domain of discourse would. This is the first known attempt at formalizing air traffic control phraseology for use in an unmanned system, and the first known flight of a vehicle controlled by natural language inputs. Outstanding problems and possible directions for future research are described.
Abstract
This paper addresses the opportunities and challenges involved in applying natural language processing techniques to the control of unmanned aerial vehicles (UAVs). The problem [...]
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An information-theoretic approach to traffic matrix estimation
Y. Zhang, D. Donoho, C. Lund, M. Roughan

Collection of open conferences in research transport (2004). Vol. 2004, 26

Abstract
Traffic matrices are required inputs for many IP network management tasks: for instance, capacity planning, traffic engineering and network reliability analysis. However, it is difficult to measure these matrices directly, and so there has been recent interest in inferring traffic matrices from link measurements and other more easily measured data. Typically, this inference problem is ill-posed, as it involves significantly more unknowns than data. Experience in many scientific and engineering fields has shown that it is essential to approach such ill-posed problems via "regularization". This paper presents a new approach to traffic matrix estimation using a regularization based on "entropy penalization". Our solution chooses the traffic matrix consistent with the measured data that is information-theoretically closest to a model in which source/destination pairs are stochastically independent. We use fast algorithms based on modern convex optimization theory to solve for our traffic matrices. We evaluate the algorithm with real backbone traffic and routing data, and demonstrate that it is fast, accurate, robust, and flexible.
Abstract
Traffic matrices are required inputs for many IP network management tasks: for instance, capacity planning, traffic engineering and network reliability analysis. However, [...]
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A Description of the Multi-Center Traffic Management Advisor (McTMA) Simulation Environment
T. Hoang

Collection of open conferences in research transport (2004). Vol. 2004, 25

Abstract
The Multi-Center Traffic Management Advisor (McTMA) tool, being developed jointly by NASA and the FAA, is being tested to aid with the coordination and management of highly congested air traffic in the "Northeast corridor" of the United States. The McTMA systems interconnect to form a data network and are being field tested in six air traffic control (ATC) facilities: Boston Air Route Traffic Control Center (ARTCC), Cleveland ARTCC, New York ARTCC, Washington ARTCC, the Philadelphia Terminal Radar Approach Control (TRACON), and the Air Traffic Control System Command Center (ATCSCC). Concept testing and validation of this highly complex system were conducted in the McTMA simulation environment at NASA Ames Research Center prior to field test. A highly innovative simulation design was employed in order to efficiently test McTMA operating in the complex Northeast Corridor. This paper presents a description of that innovative simulation architecture and its environment.
Abstract
The Multi-Center Traffic Management Advisor (McTMA) tool, being developed jointly by NASA and the FAA, is being tested to aid with the coordination and management of highly [...]
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Separating air traffic flows by allocating 3D-trajectories
N. Durand, D. Gianazza

Collection of open conferences in research transport (2004). Vol. 2004, 24

Abstract
International audience; This paper introduces two algorithms which allocate optimal separated 3D-trajectories to the main traffic flows. The first approach is a 1 vs. n strategy which applies an A* algorithm iteratively to each flow. The second is a global approach using a genetic algorithm, applied to a population of trajectory sets. The algorithms are first tried on a toy problem, and then applied to real traffic data, using operational aircraft performances. The cumulated costs of the trajectory deviations are used to compare the two algorithms.
Abstract
International audience; This paper introduces two algorithms which allocate optimal separated 3D-trajectories to the main traffic flows. The first approach is a 1 vs. n strategy [...]
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A Macro-Model for the Efficient Simulation of an ADC-based RNG
F. Pareschi, R. Rovatti, G. Setti

Collection of open conferences in research transport (2005). Vol. 2005, 18

Abstract
We present a macro-model for a true random number generator which internally exploits a pipeline analog-to-digital converter modified to operate as an interleaved chaotic map. The model is tuned to reproduce the non-idealities of a 0.35 /spl mu/m CMOS double-poly triple-metal technology. It is based on circuit-level simulations but is extremely more efficient and can be used to run the statistical tests that assure the quality of the output stream.
Abstract
We present a macro-model for a true random number generator which internally exploits a pipeline analog-to-digital converter modified to operate as an interleaved chaotic [...]
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Voice loops as cooperative aids in space shuttle mission control
J. Watts, D. Woods, J. Corban, E. Patterson, L. Hicks, R. Kerr

Collection of open conferences in research transport (2004). Vol. 2004, 23

Abstract
In domains like air traffic management, aircraft carrier operations, and space mission control, practitioners coordinate their activities through voice loops that allow communication among groups of people who are spatially separate. Voice loops have evolved into essential coordination support tools for experienced practitioners in space shuttle mission control, as well as other domains. We describe how voice loops support the coordination of activities and cognitive processes in event-driven domains like space shuttle mission control. We discuss how the loops help flight controllers synchronize their activities and integrate information, and how they facilitate directed communication and support the negotiation of interruptions. In addition, we suggest factors like attentional cues, implicit protocols, and the structure and features of the loops, which might govern the success of voice loops in the mission control domain. Our results should provide insight into the important functions that should be considered in the development of systems intended to support cooperative work.
Abstract
In domains like air traffic management, aircraft carrier operations, and space mission control, practitioners coordinate their activities through voice loops that allow communication [...]
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Stochastic traffic engineering, with applications to network revenue management
D. Mitra, Q. Wang

Collection of open conferences in research transport (2004). Vol. 2004, 21

Abstract
stochastic traffic engineering framework for optimizing bandwidth provisioning and path selection in networks is presented. The objective is to maximize revenue from serving demands, which are uncertain and specified by probability distributions. We consider a two-tier market structure, where demands in the two markets are associated with different unit revenues and uncertainties. Based on mean-risk analysis, the optimization model enables a carrier to maximize mean revenue and contain the risk that the revenue falls below an acceptable level. Our framework is intended for off-line traffic engineering design, which takes a centralized view of network topology, link capacity, and demand. We obtain conditions under which the optimization problem is an instance of convex programming and therefore efficiently solvable. We derive properties of the optimal solution for the special case of Gaussian distributions of demands. We focus on the impact of demand variability on various aspects of traffic engineering, such as link utilization, routing, capacity provisioning, and total revenue.
Abstract
stochastic traffic engineering framework for optimizing bandwidth provisioning and path selection in networks is presented. The objective is to maximize revenue from serving [...]
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ATM concept integrating trajectory-orientation and airborne separation assistance in the presence of time-based traffic flow management
E. Palmer, J. Mercer, P. Kopardekar, T. Prevot, S. Shelden, V. Battiste

Collection of open conferences in research transport (2004). Vol. 2004, 20

Abstract
This paper presents a concept for improving National Airspace System (NAS) operations through the adoption of a flexible, combination of time-based traffic flow management, trajectory-orientation, and airborne separation assistance elements. Time-based traffic flow management on a NAS-wide and local level assures that local airspace areas are not overloaded at any given time. Trajectory-based operations are used to plan and execute conflict free flight paths for upcoming flight segments. Together, these operations put flight crews in a position to utilize Airborne Separation Assistance Systems (ASAS) to deal with local separation issues, if instructed or permitted by the controller to do so. The concept outlined here is derived from a broad ATM research base, along with first-hand experience and results gathered from within the framework of Distributed Air/Ground - Traffic management (DAG-TM) research conducted over the last three years. The unique NAS traffic flow management concept proposed here draws on several existing concepts, by combining and modifying them to leverage on their particular strengths. This paper addresses the tools and technologies required and/or desirable for near-tern implementation and examines the longer-term implications.
Abstract
This paper presents a concept for improving National Airspace System (NAS) operations through the adoption of a flexible, combination of time-based traffic flow management, [...]
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Effect of Aircraft Self-Merging in Sequence on an Airborne Collision Avoidance System
D. Powell, E. Hoffman, K. Zeghal, C. Shaw, D. Ivanescu

Collection of open conferences in research transport (2004). Vol. 2004, 19

Abstract
This air traffic management research study analysed the interaction between a potential future airborne spacing application and an existing Airborne Collision Avoidance System (ACAS). The time-based airborne spacing application ‘merge behind’ was simulated in fasttime for a range of merge angles (45°, 90°, 135° and 180°), target spacing times (60 and 90 s) and altitudes (6,000 and 11,000 feet) under turbulent wind and extreme entry conditions. Trajectory pairs were analysed for potential collision alerting conditions using an ACAS simulator based on Traffic Alert and Collision Avoidance System (TCAS) II version 7 logic. Results show how, with realistic turn anticipation, the TCAS estimated time to go to Closest Point of Approach (CPA) decreased as merge angle was increased and as target spacing was reduced, but still remained above the Traffic Advisory (TA) and Resolution Advisory (RA) thresholds for the duration of all trials.
Abstract
This air traffic management research study analysed the interaction between a potential future airborne spacing application and an existing Airborne Collision Avoidance System [...]
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Relining Prestressed Concrete Cylinder Pipe, A Manufacturers Perspective
G. Smith, J. Bruny

Collection of open conferences in research transport (2004). Vol. 2004, 18

Abstract
Prestressed Concrete Cylinder Pipe (PCCP) is a rigid, pressure pipe, designed to take advantage of the compressive strength and corrosion-inhibiting properties of portland cement concrete and the tensile strength of steel. Principally used for the transmission and distribution of water in municipal systems, it was widely accepted and installed throughout the U.S. beginning in 1942. Numerous catastrophic failures across the nation have halted the use of PCCP by numerous water agencies throughout the U.S. Due to the large diameters and critical nature of these pipelines, the San Diego County Water Authority embarked on a 20-year plan to reline or replace nearly 112 km (70 mi) of large diameter PCCP. This paper describes the methods of manufacturing and installing the steel liner plates to reline existing PCCP. The project consists of relining sections of a 2438 mm (96 in.) and a 1753 mm (69 in.) pipeline. This paper describes the unique methods of collapsing the steel cans and the rapid installation requirements required by the owner. Cooperation between the agency, manufacturer, and contractor was essential for the completion of this project on slopes as great as 38%. The design and installation of this liner system allowed for a minimum reduction in hydraulic capacity.
Abstract
Prestressed Concrete Cylinder Pipe (PCCP) is a rigid, pressure pipe, designed to take advantage of the compressive strength and corrosion-inhibiting properties of portland [...]
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Energy-efficient pipelines
D. Fang, J. Teifel, D. Biermann, R. Manohar, C. Kelly

Collection of open conferences in research transport (2004). Vol. 2004, 16

Abstract
We discuss the design of energy-efficient pipelines for asynchronous VLSI architectures. To maximize throughput in asynchronous pipelines it is often necessary to insert buffer stages, increasing the energy overhead Instead of optimizing pipelines for minimum energy or maximum throughput, we consider a joint energy-time metric of the form E/spl tau//sup /spl alpha// where E is the energy per operation and /spl tau/ is the time per operation. We show that pipelines optimized for the E/spl tau//sup /spl alpha// energy-time metric may need fewer buffer stages and we give bounds when such stages can be removed. We present several common asynchronous pipeline structures and their energy-time optimized solutions.
Abstract
We discuss the design of energy-efficient pipelines for asynchronous VLSI architectures. To maximize throughput in asynchronous pipelines it is often necessary to insert buffer [...]
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