Scipedia: Documents published in 2010

Managing Optimism Biases in the Delivery of Large-Infrastructure Projects: A Corporate Performance Benchmarking Approach

Scipedia content — Tue, 02 Feb 2021 02:27:01 +0100

Optimism bias has been a considerable challenge in the planning and delivery of public services, particularly infrastructure mega projects. This has resulted in consistently underestimated costs and overestimated benefits, as well as delivery delays. This paper explores whether innovative mechanisms of collecting and publicly disseminating information about the performance of government contractors on past projects can contribute to improving the success rate of future initiatives. Drawing on international examples from North America, Europe and Asia, it is argued that the production of widely available league tables of corporate performance will have two key benefits. First, public sector procurement managers will have greater information with which to select companies with a strong reputation of successfully planning and delivering similar projects. Second, with performance rankings being used by decision-makers as part of the criteria to select future tenders, private sector partners will have greater incentive to challenge the institutional forces that cause optimism biases.

Predicting Airspace Capacity Impacts Using the Consolidated Storm Prediction for Aviation

Scipedia content — Tue, 02 Feb 2021 02:08:13 +0100

*Convective weather is currently the largest contributor to air traffic delays in the United States. In order to make effective traffic flow management decisions to mitigate these delays, weather forecasts must be made as early and as accurately as possible. A forecast product that could be used to mitigate convective weather impacts is the Consolidated Storm Prediction for Aviation. This product provides forecasts of cloud water content and convective top heights at 0- to 8-hour look-ahead times. The objective of this study was to examine a method of predicting the impact of convective weather on air traffic sector capacities using these forecasts. Polygons representing forecast convective weather were overlaid at multiple flight levels on a sector map to calculate the fraction of each sector covered by weather. The fractional volume coverage was used as the primary metric to determine convection’s impact on sectors. Results reveal that the forecasts can be used to predict the probability and magnitude of weather impacts on sector capacity up to eight hours in advance.

A rolling-horizon quadratic-programming approach to the signal control problem in large-scale congested urban road networks

Scipedia content — Tue, 02 Feb 2021 01:56:19 +0100

The paper investigates the efficiency of a recently developed signal control methodology, which offers a computationally feasible technique for real-time network-wide signal control in large-scale urban traffic networks and is applicable also under congested traffic conditions. In this methodology, the traffic flow process is modeled by use of the store-and-forward modeling paradigm, and the problem of network-wide signal control (including all constraints) is formulated as a quadratic-programming problem that aims at minimizing and balancing the link queues so as to minimize the risk of queue spillback. For the application of the proposed methodology in real time, the corresponding optimization algorithm is embedded in a rolling-horizon (model-predictive) control scheme. The control strategy's efficiency and real-time feasibility is demonstrated and compared with the Linear-Quadratic approach taken by the signal control strategy TUC (Traffic-responsive Urban Control) as well as with optimized fixed-control settings via their simulation-based application to the road network of the city centre of Chania, Greece, under a number of different demand scenarios. The comparative evaluation is based on various criteria and tools including the recently proposed fundamental diagram for urban network traffic. (C) 2009 Elsevier Ltd. All rights reserved.

Multi-Path Aggregate Flow Control for Real-Time Traffic Engineering

Scipedia content — Tue, 02 Feb 2021 01:44:44 +0100

We present an online distributed traffic engineering method for ISP networks with multi-path routing. The method is based on edge-to-edge aggregate flow control that balances load and makes the network congestion-free in real time, responding to actual traffic demands whether they are underload or overloaded. Moreover, it allows ISPs to apply various bandwidth-sharing policies to edge-to-edge flows, as desired. Our simulations confirm that the proposed method works as designed for TCP sources that have their own end-to-end congestion control mechanism and enhance the performance and the efficiency of the the network.

ECN verbose mode: a statistical method for network path congestion estimation

Scipedia content — Tue, 02 Feb 2021 01:43:27 +0100

International audience; This article introduces a simple and effective methodology to determine the level of congestion in a network with an ECN-like marking scheme. The purpose of the ECN bit is to notify TCP sources of an imminent congestion in order to react before losses occur. However, ECN is a binary indicator which does not reflect the congestion level (i.e. the percentage of queued packets) of the bottleneck, thus preventing any adapted reaction. In this study, we use a counter in place of the traditional ECN marking scheme to assess the number of times a packet has crossed a congested router. Thanks to this simple counter, we drive a statistical analysis to accurately estimate the congestion level of each router on a network path. We detail in this paper an analytical method validated by simulations which demonstrate the feasibility and the accuracy of the concept proposed and illustrate its use in a realistic scenario. We conclude this paper with possible applications and expected future work.

Ultrasonic inspection technique for NDE of fiber composite materials

Scipedia content — Tue, 02 Feb 2021 01:41:32 +0100

The constant growth of air traffic leads to increasing demands for the aircraft industry to manufacture airplanes more economically and to ensure a higher level of efficiency, ecology and safety. During the last years important improvements for fuselage structures have been achieved by application of new construction principles, employment of sophisticated and/or alternative materials, and by improved manufacturing processes. In particular the intensified application of fibre-reinforced plastics components is in the focus of current discussions and research. The main goal of an ongoing national project is to improve the existing ultrasonic test technology in such a way that it is optimally suited for the examination of CFRP multilayer structures. The B-Scan and C-Scan results are then used for the visualization of individual layers and the complete layer set-up. First results of the project revealed that with carefully selected transducers and frequencies it is possible to detect defects and irregularities in the layer structure like delaminations, fibre cracking, ondulations, missing layers etc. and even to visualize the fibre orientations in the individual layers.

Issues in acquiring, processing and visualizing large and detailed 3D models

Scipedia content — Tue, 02 Feb 2021 01:34:59 +0100

Modelling from reality using active optical geometric sensing has been a very active research area in computer graphics and vision for the last twenty years. While most elements of the modelling pipeline have reached maturity and have been adopted in several application sectors, several issues remain, particularly in the modelling of large structures and environments, as well as in the management of large, complex and detailed 3D models. This paper describes some of these issues, and outlines some of the solutions that we have proposed. These methods and approaches, as well as their current limitations, are described using different example applications: a monument (the Erechtheion), a painting (Mona Lisa), and a terrain model.

Electric vehicle fleet integration in the danish EDISON project - A virtual power plant on the island of Bornholm

Scipedia content — Tue, 02 Feb 2021 01:15:13 +0100

The Danish EDISON project has been launched to investigate how a large fleet of electric vehicles (EVs) can be integrated in a way that supports the electric grid while benefitting both the individual car owners and society as a whole through reductions in CO 2 emissions. The consortium partners include energy companies, technology suppliers and research laboratories and institutes. The aim is to perform a thorough investigation of the challenges and opportunities of EVs and then to deliver a technical platform that can be demonstrated on the Danish island of Bornholm. To reach this goal, a vast amount of research is done in various areas of EV technology by the partners. This paper will focus on the ICT-based distributed software integration, which plays a major role for the success of EDISON. Key solution technologies and standards that will accommodate communication and optimize the coordination of EVs will be described as well as the simulation work that will help to reach the goals of the project.

Sizing of a plastic chamber with air-filled balls for water hammer control

Scipedia content — Tue, 02 Feb 2021 01:08:24 +0100

Water hammer in pipelines and pipe networks can result in pipe and equipment failures and economical/environmental losses. The use of a piece of flexible plastic pipe for water hammer control is discussed and experimental data for the use of such a device are presented. The device, referred to as a plastic chamber, reduces pressures resulting from water hammer. The flexibility of the plastic chamber allows radial expansion of its walls under pressure to accommodate the excess fluid and thereby reduce water hammer-induced pressure spikes. To enhance the performance of the plastic chamber, air-filled balls are inserted into the chamber. When a sudden pressure increase takes place, the air-filled balls shrink to reduce the pressure surge. Previous experimental data on the use of the plastic chamber and the air-filled balls (inserted in a rigid chamber) are analyzed. The effect of the plastic chamber on the reduction of water hammer was formulated as a function of a dimensionless parameter related to the plastic chamber and the pipe for which water hammer is to be controlled. Furthermore, the effect of the air-filled balls was formulated and found to be a function of an analogous dimensionless parameter related to the volume/inside pressure of the balls and pipe parameters. The two effects were combined in an empirical formula for the total reduction of water hammer when using a plastic chamber with air-filled balls. The procedure allows the required water hammer reducing device to be sized to achieve a target reduction of water hammer based on the parameters of the pipe, the plastic chamber and the air-filled balls.

Stability of Spatially Distributed, Intersecting Aircraft Flows Under Sequential Conflict Resolution Schemes

Scipedia content — Tue, 02 Feb 2021 00:58:47 +0100

This paper discusses the effect of sequential conflict resolution maneuvers of an infinite aircraft flow through a finite control volume. Aircraft flow models are utilized to simulate traffic flows and determine stability. Pseudo-random flow geometry is considered to determine airspace stability in a more random airspace, where aircraft flows are spread over a given positive width. The use of this aircraft flow model generates a more realistic flow geometry. A set of upper bounds on the maximal aircraft deviation during conflict resolution is derived. Also with this flow geometry it is proven that these bounds are not symmetric, unlike the symmetric bounds derived in previous papers for simpler flow configurations. Stability is preserved under sequential conflict resolution algorithms for all flow geometries discussed in this paper.

Comment: 6 pages, 8 figures, ACC 2011 initial submission(5 pages 8 figures for ieeeconf style)

Three-Dimensional Scour at Submarine Pipelines in Unidirectional Steady Current

Scipedia content — Tue, 02 Feb 2021 00:48:39 +0100

This paper presents results of an experimental study on 3-dimensional scour at submarine pipelines with uniform sediments under a unidirectional steady current. A dimensional analysis is first conducted to identify all the important non-dimensional parameters. Laboratory experiments are then conducted to study the development of a 3-dimensional pipeline scour hole under different sets of environmental conditions. The results are recorded and the corresponding propagation velocities of the free span calculated. The effects of four parameters on the propagation velocity are studied through the conduct of several groups of experiments; each of which exclusively focuses on one particular parameter. Moreover, the scour pattern under different combinations of environmental conditions is discussed to obtain an improved understanding on the mechanism of scour hole propagation at the span shoulder of pipelines.

Execution Models for Processors and Instructions

Scipedia content — Tue, 02 Feb 2021 00:46:43 +0100

International audience; Modeling the execution of a processor and its instructions is a challenging problem, in particular in the presence of long pipelines, parallelism, and out-of-order execution. A naive approach based on finite state automata inevitably leads to an explosion in the number of states and is thus only applicable to simple minimalistic processors. During their execution, instructions may only proceed forward through the processor's datapath towards the end of the pipeline. The state of later pipeline stages is thus independent of potential hazards in preceding stages. This also applies for data hazards, i.e., we may observe data by-passing from a later stage to an earlier one, but not in the other direction. Based on this observation, we explore the use of a series of parallel finite automata to model the execution states of the processor's resources individually. The automaton model captures state updates of the individual resources along with the movement of instructions through the pipeline. A highly-flexible synchronization scheme built into the automata enables an elegant modeling of parallel computations, pipelining, and even out-of-order execution. An interesting property of our approach is the ability to model a subset of a given processor using a sub-automaton of the full execution model.

An automatic generation of schematic maps to display flight routes for air traffic controllers

Scipedia content — Tue, 02 Feb 2021 00:41:00 +0100

International audience; Aircraft must follow strict Air Traffic Control (ATC) rules. One of these rules is that aircraft have to fly over pre-defined Flight Routes (FR). Current ATC visualizations do not display FRs because they are numerous and run into each other, and thus spoil the visualization. The schematic views for metro maps are used to maximize the transmission of relevant information (lines, metro stops) of network visualization. In this paper, we will focus on two different issues. First, we show how we transposed mathematical constraints used to produce metro maps into the specific field of ATC. The view produced is a context compatible, 2D picture of a schematic maps view for Air Traffic Control. Second, we propose to investigate the generation and placement of colors to be assigned to lines of the network. The first step is to find as many colors as lines of the network. These colors must be perceptually as distinct as possible, and available in the vocabulary of colors. The second step is to solve the NP-complete problem of the optimal assignment of these colors so that close lines have the most perceptively distant color. Finally, we assess the map produced through experimentation to validate its quality.

Programmable logic device based brushless DC motor control

Scipedia content — Tue, 02 Feb 2021 00:05:31 +0100

In this article a three-phase BLDC motor controller for use in an Ultra-Light Electrical Vehicle is presented. The control is performed using a Programmable Logic Device (CPLD), which doesn’t require any additional processor. In this way a robust and low-complexity control is obtained. For extending the speed range of the BLDC, a phase advance circuit is implemented as well. The power consumption of the controller is very low which is an interesting feature in battery applications.

First findings on the controller's mental model in sectorless air traffic management

Scipedia content — Mon, 01 Feb 2021 23:54:26 +0100

In sectorless air traffic management the airspace is considered as one piece instead of partitioning it into sectors. The air traffic controllers are no longer in charge of sectors but are given responsibility for a certain number of aircraft during their entire flight. This entails that the controller has to keep track of several different traffic situations geographically spread out over a potentially large area. Of course, such a considerable change of concept has implications on the controllers' mental model and the way conflicts are solved. This paper describes the shift of the controller's mental model away from one geographically limited view with long-term planning to several global views with short-term planning. It is illustrated how this altered mental model also implies changes of the controller's tasks and conflict solving. Real-time simulations within DLR's LRM2020 project have shown that working with a sectorless concept is possible and feasible if the co ntroller is supported by suitable conflict detection. The details and results of these simulations are given and the effects of the altered mental model are analyzed. It is furthermore explained how a sectorless concept could change controller work away from controller teams consisting of executive and planner to a one-person workplace supported by a conflict detection. At the same time the principle that two pairs of eyes are better than one is retained. The controller's tasks are not reduced to monitoring jobs but the essential conflict avoidance task remains.

Mnemonic Lossy Counting: An Efficient and Accurate Heavy-hitters Identification Algorithm

Scipedia content — Mon, 01 Feb 2021 23:54:02 +0100

International audience; Identifying heavy-hitter traffic flows efficiently and accurately is essential for Internet security, accounting and traffic engineering. However, finding all heavy-hitters might require large memory for storage of flows information that is incompatible with the usage of fast and small memory. Moreover, upcoming 100Gbps transmission rates make this recognition more challenging. How to improve the accuracy of heavy-hitters identification with limited memory space has become a critical issue. This paper presents a scalable algorithm named Mnemonic Lossy Counting (MLC) that improves the accuracy of heavy-hitters identification while having a reasonable time and space complexity. MLC algorithm holds potential candidate heavy-hitters in a historical information table. This table is used to obtain tighter error bounds on the estimated sizes of candidate heavy-hitters. We validate the MLC algorithm using real network traffic traces, and we compared its performance with two state-of-theart algorithms, namely Lossy Counting (LC) and Probabilistic Lossy Counting (PLC). The results reveal that: 1) with same set of parameters and memory usage, MLC achieves between 31.5% and 6.67% fewer false positives than LC and PLC. 2) MLC and LC have a zero false negative ratio, whereas 38% of the cases PLC has a non-zero false negatives and PLC can miss up to 4.4% of heavy-hitters. 3) MLC has a slightly lower memory cost than LC during the first few windows and its memory usage decreases with time, when PLC memory usage declines sharply. 4) MLC has similar runtime than LC, and smaller time than PLC.

Benefits Assessment Methodology for an Air Traffic Control Tower Advanced Automation System

Scipedia content — Mon, 01 Feb 2021 23:51:05 +0100

†‡ ‡ ‡ § This paper presents a benefits assessment methodology for an air traffic control tower advanced automation system called the Tower Flight Data Manager (TFDM), which is being considered for development by the FAA to support NextGen operations. The standard FAA benefits analysis methodology is described, together with how it has been tailored to the TFDM application to help inform the development process and the business case for system deployment. Parts of the methodology are illustrated through data analysis and modeling, and insights are presented to help prioritize TFDM capability development. I. Introduction N air traffic control tower advanced automation system known as the Tower Flight Data Manager (TFDM) is being considered for development by the Federal Aviation Administration (FAA) 1 . It is designed to replace the numerous standalone systems within current towers with an integrated technology suite comprising an advanced surveillance display system, an electronic flight strip/data manager system and a set of decision support tools (DSTs), as shown in Figure 1. The TFDM system is designed to provide the automation environment necessary to support future flexible airport and terminal airspace operations for Next Generation Air Transportation System (NextGen) towers 2 . The capabilities provided by the TFDM system should enable multiple system benefits, such as better performance during severe weather and other off-nominal conditions; reduced surface delay, taxi time and fuel burn (with associated improved operational and environmental performance); and enhanced safety.

Multi-Commodity Flow Traffic Engineering with Hybrid MPLS/OSPF Routing

Scipedia content — Mon, 01 Feb 2021 23:26:25 +0100

The common objective of network traffic engineering is to minimize the maximal link utilization in a network in order to accommodate more traffic and reduce the chance of congestion. Traditionally this is done by either optimizing OSPF link weights or using MPLS tunnels to direct traffic. However, they both have problems: OSPF weight optimization triggers network-wide convergence and significant traffic shift, while pure MPLS approach requires a full mesh of tunnels to be configured throughout the network. This paper formulates the traffic engineering problem as a Multi-Commodity Flow problem with hybrid MPLS/OSPF routing (MCFTE). As a result, the majority of traffic is routed by regular OSPF, while only a small number of MPLS tunnels are needed to fine-tune the traffic distribution. It keeps OSPF link weights unchanged to avoid triggering network convergence, and needs far fewer MPLS tunnels than the fullmesh to adjust traffic. Compared with existing hybrid routing approaches, MCFTE achieves the optimal link utilization, runs about two orders of magnitude faster, and is more robust against measurement inaccuracy in traffic demand.

Impact of Plug-in Hybrid Electric Vehicles (PHEVs) on the French Electric Grid

Scipedia content — Mon, 01 Feb 2021 23:15:53 +0100

Currently the automotive sector is undergoing a major change. During the next years it is expected that there will be a considerable increase in the numbers of Plug-in Hybrid Electric Vehicles (PHEVs). Based on different charging scenarios, this paper investigates the impact of PHEVs on the French electric grid. Solutions are proposed to increase the maximum penetration rate. Hence we estimate that the French electric grid can accommodate 72% of PHEVs in 2015. This makes it possible to reduce oil imports for France by 22.5% and CO2 emissions due to road transport by 18%.

One More Weight is Enough: Toward the Optimal Traffic Engineering with OSPF

Scipedia content — Mon, 01 Feb 2021 23:15:06 +0100

Traffic Engineering (TE) leverages information of network traffic to generate a routing scheme optimizing the traffic distribution so as to advance network performance. However, optimize the link weights for OSPF to the offered traffic is an known NP-hard problem. In this paper, motivated by the fairness concept of congestion control, we firstly propose a new generic objective function, where various interests of providers can be extracted with different parameter settings. And then, we model the optimal TE as the utility maximization of multi-commodity flows with the generic objective function and theoretically show that any given set of optimal routes corresponding to a particular objective function can be converted to shortest paths with respect to a set of positive link weights. This can be directly configured on OSPF-based protocols. On these bases, we employ the Network Entropy Maximization(NEM) framework and develop a new OSPF-based routing protocol, SPEF, to realize a flexible way to split traffic over shortest paths in a distributed fashion. Actually, comparing to OSPF, SPEF only needs one more weight for each link and provably achieves optimal TE. Numerical experiments have been done to compare SPEF with the current version of OSPF, showing the effectiveness of SPEF in terms of link utilization and network load distribution.

Workcell-based Supply Chain Management

Scipedia content — Mon, 01 Feb 2021 22:59:58 +0100

Jabil is well known as a model of workcell production. In the past few years, Jabil (Guangzhou) starts to apply the workcell production principles in managing a supply chain, resulting in better control on the demand and supply uncertainty among multiple supply chain partners. Here a new supply chain management mode—Workcell-based Supply Chain Management (WSCM) is proposed. The WSCM is customer-centered, coordinates the relationships of supply chain participants in a U-shape topology, and is able to effectively control and reduce the occurrence and transfer of demand uncertainty in supply chain management.

Multi-class Boosting for Early Classification of Sequences

Scipedia content — Mon, 01 Feb 2021 22:57:07 +0100

Consider the problem of driver behavior recognition from images captured by a camera installed in a vehicle [4]. Recognition of driver behavior is crucial for driver assistance systems that make driving comfortable and safe. One notable requirement for real applicatioins is that we would like to predict and classify a behavior as quickly as possible: if we detect a sign of dangerous movements such as mobile phone use while driving, we would like to warn the driver quickly before the behavior causes any accidents. This kind of classification task is called “early classification (recognition),” and is important for many practical problems including on-line handwritten character recognition, and speech recognition systems. In this paper, we focus one of the most famous discriminative models, i.e. Adaboost [1, 2], and extend it for early classification of sequences. While existing researches (e.g. [5, 6]) have studied only a binary classification problem, we present a multi-class extension of Adaboost for early classification, called Earlyboost.MH (Fig. 1). In this paper, we propose an efficient multi-class Adaboost for early classification by combining multi-class Adaboost.MH [3] and the early classification Boosting (Earlyboost [6]),

Taking into account of safety in models of railroad traffic management and optimization

Scipedia content — Mon, 01 Feb 2021 22:48:10 +0100

International audience; The growing increase in the volume of transportation system’s flows has entailed congestion problems of traffic. For railway transport as well as other transportation networks, the increase in traffic demand—without further investing in infrastructure—stands as a chief priority for operators. As a matter of fact they take special interest in improving the operating possibilities for some critical points of the rail network. In order to resolve the problems inherent in the operational management of rail transport traffic, optimization experts have operated mathematical optimization techniques and problem resolving methods that have been developed as part of operational research aimed at keeping a good level of availability. However, these optimization approaches have considerably contributed to balancing and stabilizing the flows of road and rail networks but still do not guarantee security at system, environmental and human levels. This work introduces a management and regulatory approach to rail traffic and takes into account the security component while chiefly aiming at improving and keeping a “good” level of security. To this end, we have set up a security modelling approach based on a hybrid risk analysis, both quantitative and qualitative. This approach seeks to develop a structured framework allowing the integration of the security component into an explicit generic optimization model in accordance with the operating constraints in use by rail optimization methods. On the one hand, this approach constitutes a formal checking process for the management and optimization of traffic even though they are subject to failures. On the other, it is a set of modelling tools and a methodological structure allowing managing and controlling risks at the level of a rail transport system.

Estimating arterial traffic conditions using sparse probe data

Scipedia content — Mon, 01 Feb 2021 22:40:02 +0100

Estimating and predicting traffic conditions in arterial networks using probe data has proven to be a substantial challenge. In the United States, sparse probe data represents the vast majority of the data available on arterial roads in most major urban environments. This article proposes a probabilistic modeling framework for estimating and predicting arterial travel time distributions using sparsely observed probe vehicles. We evaluate our model using data from a fleet of 500 taxis in San Francisco, CA, which send GPS data to our server every minute. The sampling rate does not provide detailed information about where vehicles encountered delay or the reason for any delay (i.e. signal delay, congestion delay, etc.). Our model provides an increase in estimation accuracy of 35% when compared to a baseline approach for processing probe vehicle data.

Designing a smarter travel strategy for Limerick City using precedent studies and focus groups

Scipedia content — Mon, 01 Feb 2021 22:22:52 +0100

eer-reviewed Almost 7 out of 10 people in Limerick drove to work, school, or college in 2006 with 65% of residents commuting a distance of 1 to 9km Successful change has been implemented in European and, more recently, in UK and Australian cities, to reverse the effects of unsustainable travel. For example in Groningen in the Netherlands, an average of 1.4 urban bicycle trips per person per day were made, making up more than 50% of the total trips in 2008 .This shows the potential that exists for achieving a Smarter Travel Limerick with the associated benefits which are well documented. This research aims to create a rational basis for designing and implementing a plan for Smarter Travel Limerick with particular reference to a community engagement strategy. The objective of the study is to develop a local culture of Smarter Travel in Limerick communities using best international practice and thereby achieve behavioural change in travel mode choice. As part of this research census and survey travel data for Limerick and data from the Limerick focus groups together with the data from the chosen international exemplar city precedent studies is analysed. This data is complex and is of both quantitative and qualitative type. The analysis provides a rationale to allow proposals for an appropriate Community Engagement strategy to be formulated. Literature on Smarter Travel is also reviewed including results from a comprehensive study of six international exemplar Smarter Travel Cities. Current travel modes and travellers' mode choice criteria in Limerick city are investigated considering the literature review and the findings of the data analysis. Finally, a design and implementation plan with particular emphasis on community engagement for Limerick Smarter Travel is discussed.

Vectorization of gridded urban land use data

Scipedia content — Mon, 01 Feb 2021 21:59:15 +0100

In the digital entertainment industry, cities are one of the largest artifacts modeled by artists. One alternative to modeling an entire city by hand is to use an urban simulation. Often, those simulations use a gridded terrain representation. Translating gridded simulation results into a more continuous, realistic representation useful in games and film can often be difficult. Our vectorization process transforms gridded urban land use data into a representation useful in entertainment pipelines and many GIS or online mapping tools. The process has three major phases. In the first phase, the raster data is analyzed and the transportation layer is abstracted and filtered. Next, the city blocks are constructed from the raster data. Third, the blocks are subdivided and land use and density are assigned to each constructed parcel. The results are much smoother than the gridded input, but maintain the land use patterns of that input. We output these results in a GIS format readable by a wide range of modeling tools.

Evaluation of an Active Safety Light using Virtual Test Drive within Vehicle in the Loop

Scipedia content — Mon, 01 Feb 2021 21:43:39 +0100

Driving at night time increases the risk of accidents because the driver's perception is reduced to the limited area of the environment which is illuminated by the car's head lights. In the study presented in this paper, the tool Vehicle in the Loop (VIL) is used the first time to research the potential of a new light function. VIL is a Virtual Reality application and simulation setup which allows for testing driver assistance systems in critical driving situations while driving a real car, but without the risk of collisions with real objects. VIL is based on the Virtual Test Drive (VTD) simulation software. The Active Safety Light is an advanced light functionality which illuminates the potential escape path a driver should take in order to avoid an imminent accident. The two main results of this first field study are, that VIL is suitable to study advanced light functions and that the Active Safety Light supports the driver in critical situations. The driver reacts nearly 60 ms faster and the situation is estimated as more critical so that the driver brakes instinctively harder, i.e. the break pressure is increased by almost a factor of two.

A design flow based on modular refinement

Scipedia content — Mon, 01 Feb 2021 21:42:28 +0100

We propose a practical methodology based on modular refinement to design complex systems. The methodology relies on modules with latency-insensitive interfaces so that the refinements can change the timing contract of a module without affecting the overall functional correctness of the system. Such refinements can exacerbate the unit testing problem for modules whose specifications admit a set of output behaviors for the same input (non-determinism), or modules whose input behavior may be affected by past outputs (feedback). We avoid the difficult problem of generating appropriate unit tests for such modules by using system-level tests as unit tests to verify the correctness of refined modules. We illustrate our methodology by showing how one might develop a microprocessor with an in-order pipeline. We then develop a superscalar pipeline using the in-order pipeline as the starting point. Our methodology leverages the effort of design exploration to reduce the effort of specifying interface contracts and unit testing.

A dual image processing pipeline camera with CE applications

Scipedia content — Mon, 01 Feb 2021 21:38:14 +0100

The implementation of a dual image processing pipeline camera on a state-of-art FPGA system is described. This camera can simultaneously acquire dual images of a scene and process, analyze and merge both images to enable a range of real-time image enhancement algorithms to be explored. Several examples of image enhancement algorithms implemented on the prototype camera are described. non-peer-reviewed

OPTIMIZING B-SPLINES USING GENETIC ALGORITHMS APPLIED TO AIR-TRAFFIC CONFLICT RESOLUTION

Scipedia content — Mon, 01 Feb 2021 21:24:27 +0100

International audience; Conflict resolution has always been a sensitive matter in air-traffic management. Current European projects aim partial or total automation of air traffic control to deal with the constant growth of air traffic. Technological advances on flight management system allows us to consider an automatic conflict resolution using continuous trajectories. In this paper, we present a new methodology that, first, relies on B-splines to model trajectories, secondly models air-traffic conflict resolution as an optimization problem whose decision variables are the spline control points. Finally, we use genetic algorithms to tackle this optimization problem in order to generate optimal conflict-free situations.

On the use of network QoS reputation for vertical handover decision making

Scipedia content — Mon, 01 Feb 2021 21:14:49 +0100

International audience; Efficient vertical handover mechanisms are required to provide service continuity over available and upcoming heterogeneous wireless access networks. They should provide low delays and good accuracy to meet service requirements. In the literature, proposed mechanisms rely on a rich knowledge of users' ambient environments and contexts. The outcomes are complex mechanisms that require significant amount of resources and processing time. Reputation is a rating concept already used in ad hoc security, social and business fields. It is intended to deliver fast decisions based on the analysis of users' experiences in similar conditions. In this paper, we propose the use of a reputation system to speed up vertical handover (VHO) decisions in complex wireless environments. The proposed approach can be used for initial attachments and VHO decisions. It is based on simplified rating functions reflecting a contextual QoS, experienced by previous users. Discussions and early performance evaluations are provided

Assessment of the Congestion Impacts of Fatal Accidents Using SCOOT Data

Scipedia content — Mon, 01 Feb 2021 20:34:08 +0100

This study focuses on the assessment of the congestion impacts of fatal accidents. The paper addresses the current paucity of research into accident induced congestion levels outside of Motorway/Freeway environments, and using the SCOOT traffic control system, provides an assessment of these impacts in more heterogeneous urban environments. Levels of induced congestion are found to vary significantly according to the temporal and spatial settings in which they occur, with only accidents that occur in either peak periods or constricted network layouts producing significant induced congestion externalities in monetary terms. The detailed spatial and temporal resolutions required for such forecasts are subsequently discussed, as these raise a number of issues for SCOOT and ITS data more generally, if such analyses are to become more detailed, sophisticated, and ultimately automated, across a range of complex temporal and spatial settings.

The limits of public policy intervention in urban logistics: The case of Vicenza (Italy) and lessons for other European cities

Scipedia content — Mon, 01 Feb 2021 20:11:05 +0100

International audience; For over fifteen years, the subject of urban logistics has preoccupied many, including public decision-makers. This paper seeks to identify the limits beyond which regulations restricting vehicle access to limited traffic zones may be sanctioned for abuse of power. Here, we present the case of Vicenza (Italy), which has implemented very restrictive regulations. Based on this case study, certain lessons can be drawn for other urban areas in Europe.

Airspace structure, future ATC systems, and controller complexity reduction

Scipedia content — Mon, 01 Feb 2021 19:53:30 +0100

ce structure is a key factor influencing controller cognitive complexity as it forms a basis for abstractions simplifying controller mental models of air traffic situations. In evaluating the feasibility of new Concepts of Operations (Con-Ops), it is important to consider the effects of changes to the structure of the system and its related impacts on controller cognitive complexity. Examples of key cognitive complexity considerations for future ATC systems are identified by examining three opportunities to modify airspace structure. A part task experiment was used to further investigate the impact of one of those opportunities on controller cognitive complexity, the introduction of time-based control. The hypothesis of structure's impact on controller complexity was supported through an innovative aircraft complexity assessment technique Benefits of time-based control were shown both in terms of controller performance and subjective complexity rating results.

Investigation of a Masking Countermeasure against Side-Channel Attacks for RISC-based Processor Architectures

Scipedia content — Mon, 01 Feb 2021 19:53:14 +0100

Side-Channel Attacks (SCAs) present a serious threat to the security of crypto-systems. In this paper, we show how a pipelined embedded processor opens the door to such attacks. To illustrate our approach, a concrete evaluation of the Xilinx’s MicroBlaze soft-core processor is conducted. From these results, we suggest a new masking countermeasure suited for RISC-based architectures. The efficiency and limits of the proposed solution are finally evaluated.

Electric vehicle: infrastructure regulatory requirements

Scipedia content — Mon, 01 Feb 2021 19:47:55 +0100

In 2009 the European Union (EU) Directive on Renewable Energy placed an obligation on each Member State to ensure that 10% of transport energy (excluding aviation and marine transport) come from renewable sources by 2020. The Irish Government intends to achieve part of this target by making sure that 10% of all vehicles in its transport fleet are powered by electricity by 2020. Stakeholder groups include but are not limited to policy makers, the public, regulatory bodies, participants in the electricity retail market, the transmission and distribution system grid operators, the automotive industry, private enterprise, civil engineers, electrical engineers, electricians, architects, builders, building owners, building developers, building managers, fleet managers and EV owners. Currently it appears both internationally and Nationally the automotive industry is focused on EV manufacture, governments and policy makers have highlighted the potential environmental and job creation opportunities while the electricity sector is preparing for an additional electrical load on the grid system. The focus of this paper is to produce an international EV roadmap. A review of current international best practice and guidelines under consideration or recommended is presented. An update on any EV infrastructure charging equipment standards is also provided. Finally the regulatory modifications to existing National legislation as well as additional infrastructure items which may need control via new regulations are identified.

Probabilistic Risk Assessment for FPSO Topside Structures Under Drop Impact: An Application to Pipeline Protections

Scipedia content — Mon, 01 Feb 2021 19:36:52 +0100

In offshore structural design, it is necessary to evaluate probabilistic risk so that the topside structure has sufficient capacity to resist the effects of accidental loads such as drop impact, helicopter impact, vessel collision, fire, and explosion. Most engineers in the offshore industry, however, have difficulties in estimating a reliable risk value because there are still too many uncertainties in computing the probability of exceeding a target structural damage where the guideline for hazard analysis, which provides design load, is quite well described. Therefore, a framework to compute reasonable probability of structural failure is proposed in this paper. 88 impact scenarios were applied to a pipeline protection system on a topside module of Nexus genetic FPSO in order to perform regression analysis for structural damage. For risk calculation, the hazard analysis in this study is based on the detail engineering report worked by Ramboll Oil & Gas.Copyright © 2011 by ASME

Which stakeholders benefit from rescheduling more freight deliveries to the off-peak hours?: results of a pilot study in the retail industry

Scipedia content — Mon, 01 Feb 2021 19:31:51 +0100

Introduction to the connected cruise control and related human factors considerations

Scipedia content — Mon, 01 Feb 2021 19:20:03 +0100

Connected Cruise Control (CCC) is a new approach to driver assistance that avoids some of the problems associated with autonomous driver assistance by advising optimal driver behaviour via a human-machine interface. Yet the characteristics of this advice can have a negative impact on driver distraction and additional task demand. While the system is still under development, an evaluation of system effects is needed to identify potential safety issues at an early stage in the design process. For this reason an introduction to CCC is provided, followed by a discussion of how advice attributes can generate distraction and add task demand. Finally, two human factors constructs are provided that can indicate the effects of systems characteristics on driver performance.

Multimodal presentation of local danger warnings for drivers: A situation-dependent assessment of usability

Scipedia content — Mon, 01 Feb 2021 16:26:50 +0100

This study addresses how advanced driver assistance systems (ADAS) should communicate with drivers, focusing on the local danger warning function. To achieve high-quality assistance, the communication mode needs to be adaptive to changes in driving situation (driver's state, workload and environment). In a user study investigating different warning communication modes, drivers were required to assess the usability of each communication mode in five different driving situations. Results revealed that the driving situation significantly affected the perceived usefulness of each warning communication mode, mainly due to the use of modality. Moreover, regardless of communication mode, the local danger warning function was considered as the most useful in the low visibility situation and the least useful in the highly demanding driving situation. Findings of this study can be applied to the design of ADAS in general.

Geospatial Databases and Augmented Reality Visualization for Improving Safety in Urban Excavation Operations

Scipedia content — Mon, 01 Feb 2021 16:18:10 +0100

The U.S. has more than 14 million miles of buried pipelines and utilities, many of which are in congested urban environments where several lines share the underground space. Errors in locating excavations for new installation or for repair/rehabilitation of existing utilities can result in significant costs, delays, loss of life, and damage to property (Sterling 2000). There is thus a clear need for new solutions to accurately locate buried infrastructure and improve excavation safety. This paper presents ongoing research being collaboratively conducted by the University of Michigan and DTE Energy (Michigan's largest electric and gas utility company) that is investigating the use of Real-Time Kinematic global positioning system (GPS), combined with Geospatial Databases of subsurface utilities to design a new visual excavator-utility collision avoidance technology. 3D models of buried utilities are created from available geospatial data, and then superimposed over an excavator's work space using geo-referenced Augmented Reality (AR) to provide the operator and the spotter(s) with visual information on the location and type of utilities that exist in the excavator's vicinity. This paper describes the overall methodology and the first results of the research.

GATEway: symbiotic inter-domain traffic engineering

Scipedia content — Mon, 01 Feb 2021 16:16:19 +0100

There are a group of problems in networking that can most naturally be described as optimization problems (network design, traffic engineering, etc.). There has been a great deal of research devoted to solving these problems, but this research has been concentrated on intra-domain problems where one network operator has complete information and control. An emerging field is inter-domain engineering, for instance, traffic engineering between large autonomous networks. Extending intra-domain optimization techniques to inter-domain problems is often impossible without the information available within a domain, and providers are often unwilling to share such information. This paper presents an alternative: we propose a method for traffic engineering that does not require sharing of important information across domains. The method extends the idea of genetic algorithms to allow symbiotic evolution between two parties. Both parties may improve their performance without revealing their data, other than what would be easily observed in any case. We show the method provides large reductions in network congestion, close to the optimal shortest path routing across a pair of networks. The results are highly robust to measurement noise, the method is very flexible, and it can be applied using existing routing.

Modeling air traffic throughput and delay with network cell transmission model

Scipedia content — Mon, 01 Feb 2021 15:51:11 +0100

❖ A model has been developed that models the movement of flights across a network and provides for a tradeoff between minimal delay and maximal throughput. ❖ Inspired by the Cell Transmission Model, this model captures the movement of aircraft from cell to cell within a network, and determines the optimal routing of aircraft through congested areas. ❖ Ongoing work to determine efficient integer solutions to the problem & finding cases that yield integer solutions. ❖ Incorporating stochasticity with inclusion of parameters to model randomness in flight departure times and its effect on delay and throughput.

Geometric Model of a Narrow Tilting CAR using Robotics formalism

Scipedia content — Fri, 29 Jan 2021 00:45:34 +0100

International audience; The use of an Electrical narrow tilting car instead of a large gasoline car should dramatically decrease traffic congestion, pollution and parking problem. The aim of this paper is to give a unique presentation of the geometric modeling issue of a new narrow tilting car. The modeling is based on the modified Denavit Hartenberg geometric description, which is commonly used in Robotics. Also, we describe the special Kinematic of the vehicle and give a method to analyze the tilting mechanism of it. Primarily experimental results on the validation of the geometrical model of a real tilting car are given.

Soilse: A decentralized approach to optimization of fluctuating urban traffic using Reinforcement Learning

Scipedia content — Fri, 29 Jan 2021 00:37:56 +0100

Increasing traffic congestion is a major problem in urban areas, which incurs heavy economic and environmental costs in both developing and developed countries. Efficient urban traffic control (UTC) can help reduce traffic congestion. However, the increasing volume and the dynamic nature of urban traffic pose particular challenges to UTC. Reinforcement Learning (RL) has been shown to be a promising approach to efficient UTC. However, most existing work on RL-based UTC does not adequately address the fluctuating nature of urban traffic. This paper presents Soilse1, a decentralized RL-based UTC optimization scheme that includes a nonparametric pattern change detection mechanism to identify local traffic pattern changes that adversely affect an RL agent's performance. Hence, Soilse is adaptive as agents learn to optimize for different traffic patterns and responsive as agents can detect genuine traffic pattern changes and trigger relearning. We compare the performance of Soilse to two baselines, a fixed-time approach and a saturation balancing algorithm that emulates SCATS, a well-known UTC system. The comparison was performed based on a simulation of traffic in Dublin's inner city centre. Results from using our scheme show an approximate 35%–43% and 40%–54% better performance in terms of average vehicle waiting time and average number of vehicle stops respectively against the best baseline performance in our simulation.

Linear complexity context-free parsing pipelines via chart constraints

Scipedia content — Fri, 29 Jan 2021 00:36:08 +0100

In this paper, we extend methods from Roark and Hollingshead (2008) for reducing the worst-case complexity of a context-free parsing pipeline via hard constraints derived from finite-state tagging pre-processing. Methods from our previous paper achieved quadratic worst-case complexity. We prove here that alternate methods for choosing constraints can achieve either linear or O(Nlog2N) complexity. These worst-case bounds on processing are demonstrated to be achieved without reducing the parsing accuracy, in fact in some cases improving the accuracy. The new methods achieve observed performance comparable to the previously published quadratic complexity method. Finally, we demonstrate improved performance by combining complexity bounding methods with additional high precision constraints.

Optimizing Flight Departure Delay and Route Selection under En Route Convective Weather

Scipedia content — Fri, 29 Jan 2021 00:32:53 +0100

*† ‡ This paper presents a linear Integer Programming model for managing air traffic flow in the United States. The decision variables in the model are departure delays and predeparture reroutes of aircraft whose trajectories are predicted to cross weather-impacted regions of the National Airspace System. The model assigns delays to a set of flights while ensuring their trajectories are free of any conflicts with weather. In a deterministic setting, there is no airborne holding due to unexpected weather incursion in a flight’s path. The model is applied to solve a large-scale traffic flow management problem with realistic weather data and flight schedules. Experimental results indicate that allowing rerouting can reduce departure delays by nearly 57%, but it is associated with an increase in total airborne time due to longer routes flown by aircraft. The computation times to solve this problem were significantly lower than those reported in the earlier studies.

Quantifying displaced carbon dioxide emissions from electric vehicles in Ireland

Scipedia content — Fri, 29 Jan 2021 00:27:49 +0100

Under EU Directive 2009/28/EC on Renewable Energy each Member State is mandated to ensure that 10% of transport energy (excluding aviation and marine transport) comes from renewable sources by 2020. The Irish Government intends to achieve this target with a number of policies including an increase in the use of biofuels in transport by 3% by 2010 and ensuring that 10% of all vehicles in the transport fleet are powered by electricity by 2020. Electric vehicles (EVs) do not emit exhaust fumes in the same manner as traditional internal combustion engine (ICE) vehicles. The optimal benefits of EVs can only be truly achieved if EVs are deployed effectively, so that exhaust pipe gaseous emissions are not fully displaced to the electricity sector. This paper examines the potential contributions that Plug in Hybrid Electric Vehicles can make in reducing carbon dioxide. The paper presents the results of the generation expansion model for Northern Ireland and the Republic of Ireland built using the dynamic programming based long term generation expansion planning tool called the Wien Automatic System Planning IV tool. The model optimizes power dispatch using hourly electricity demand curves for each year up to 2020, while incorporating generator characteristics and certain operational requirements such as energy not served and loss of load probability while satisfying constraints on environmental emissions, fuel availability and generator operational and maintenance costs. In order to simulate the effect of PHEV, two distinct charging scenarios are applied based on a peak tariff and an off peak tariff. The importance and influence of the charging regime on the amount of energy used and gaseous emissions displaced is determined and briefly discussed.

A Human-in-the-Loop Investigation of Multi-Sector Planning Operations for the NextGen Mid-Term

Scipedia content — Fri, 29 Jan 2021 00:24:00 +0100

human-in-the-loop simulation was conducted to evaluate a concept for introducing multi-sector trajectory planning operations into en route air traffic facilities in the NextGen Mid-Term timeframe. Multi-sector planning tools and procedures for local area traffic flow management were developed, and then tested using two different service provider team configurations. In one condition, local area flow planning was performed by the traffic management coordinator and area supervisor. A second condition added a new, dedicated multi-sector planner position to the planning team. A set of eight convective weather and traffic load scenarios was used to evaluate the operational feasibility, potential benefits, and tool performance requirements of each condition. Significant improvements in weather avoidance and controller workload were observed in the multi-sector planner condition but no significant improvement was observed in user efficiency. Results indicate that multisector planning operations are effective and feasible in either team configuration.

Air traffic conflict resolution via B-splines and genetic algorithms

Scipedia content — Fri, 29 Jan 2021 00:19:43 +0100

From the beginning, the most critical point of Air Traffic Control was to ensure safety separation distance between airplanes. To achieve this goal, a safety standard separation has been defined : 5 Nm (Nautical miles) horizontally and 1000 feet vertically (separation box). Air traffic controllers are responsible for ensuring the respect of this separation rules. In the future, Air Traffic Management (ATM) will have to deal with a doubling of the air traffic while ensuring at least equivalent standards of safety [1]. The SESAR european project aims to find solutions to this problematic by automating the current system or by providing a decision support to the air traffic controllers in order to decrease their workload. Considering the technological advances on the airplane Flight Managment System (FMS) we will explore in this paper the possibility of a full automation generating continuous trajectories that new FMS can follow.

Selecting conflict resolution maneuvers based on minimum fuel burn

Scipedia content — Fri, 29 Jan 2021 00:03:18 +0100

The effects of selecting conflict resolution maneuvers based on minimum delay are compared to resolution selection based on minimum fuel burn. The algorithm used in this study is designed to support an automated separation assurance capability for next generation air traffic management systems. The algorithm resolves detected conflicts that are projected to be between three and twenty minutes prior to loss of separation. A total of nine fast-time simulations were conducted, each representing thirty six hours of traffic on a "low weather," high volume day with mixed aircraft types, flight phases and conflict geometries. The test matrix varied airspace region and resolution selection criteria. System-wide effects such as the number of conflicts, fuel burn, delay, and maneuver type are analyzed and compared to the same metrics when maneuvers are selected based on delay. When selecting resolutions based on fuel burn, the cumulative fuel burn of the system decreases by 27% and the delay increases by 25% when compared to resolutions selected based on minimum delay. Results indicate that speed maneuvers are the most efficient when selecting resolutions based on minimum fuel burn. Horizontal and vertical maneuvers were executed with similar frequency when comparing delay and fuel burn.

Leveraging router programmability for traffic matrix computation

Scipedia content — Thu, 28 Jan 2021 23:54:32 +0100

Traffic matrices are used by Internet Service Providers as an input for many business-critical activities like capacity planning and traffic engineering. Despite their importance, current approaches for computing traffic matrices are either unpractical or not arbitrarily accurate. In this paper, we propose a novel distributed architecture in which programmable routers autonomously compute parts of the whole traffic matrix. Our proposal conjugates router programmability with some ideas firstly proposed by Varghese and Estan [17] and avoids the need for packet sampling exploiting highly optimized counting mechanisms, already available on commercial routers. We describe our architecture and analyze main implementative issues. Also, we show the viability of our solution by describing a prototypical implementation and some experimental results.

Limitations and Possibilities of Path Trading between Autonomous Systems

Scipedia content — Thu, 28 Jan 2021 23:47:06 +0100

When forwarding packets in the Internet, Autonomous Systems (ASes) frequently choose the shortest path in their network to the next-hop AS in the BGP path, a strategy known as hot-potato routing. As a result, paths in the Internet are suboptimal from a global perspective. For peering ASes who exchange traffic without payments, path trading - complementary deviations from hot- potato routing - appears to be a desirable solution to deal with these inefficiencies. In recent years, path trading approaches have been suggested as means for interdomain traffic engineering between neighboring ASes, as well as between multiple ASes to achieve global efficiency. Surprisingly, little is known on the computational complexity of finding path trading solutions, or the conditions which guarantee the optimality or even approximability of a path trading protocol. In this paper we explore the computational feasibility of computing path trading solutions between peering ASes. We first show that finding a path trading solution between a pair of ASes is NP- complete, and that path-trading solutions are even NP-hard to approximate. We continue to explore the feasibility of implementing policies between multiple ASes and show that, even if the bilateral path trading problem is tractable for every AS pair in the set of trading ASes, path trading between multiple ASes is NP- hard, and NP-hard to approximate as well. Despite the above negative results, we show a pseudo-polynomial algorithm to compute path trading solutions. Thus, if the range of the instances is bounded, we show one can compute solutions efficiently for peering ASes. We evaluate the path trading algorithm on pairs of ASes using real network topologies. Specifically, we use real PoP-level maps of ASes in the Internet to show that path trading can substantially mitigate the inefficiencies associated with hot-potato routing.

Control Space Analysis of Three-Degree Decelerating Approaches at Amsterdam Airport Schiphol

Scipedia content — Thu, 28 Jan 2021 23:43:47 +0100

msterdam Schiphol Airport currently uses a Continuous Descent Approach during night time operations only, due to reduced runway capacity caused by unpredictable individual aircraft behavior. The Three-Degree Decelerating Approach (TDDA) has been developed to increase predictability and runway capacity by switching the sepa- ration task from Air Traffic Control to the pilot on board the aircraft. The research described in this paper identifies the factors that influence the control space of aircraft performing a TDDA in a real-life setting. Control space is defined as the difference between the maximum and minimum duration to perform the TDDA. Using different control strategies, a fast approach or slow approach can be flown. A fast-time simulation tool was built to perform simulations with different aircraft types, initial weights, wind speeds and directions. Preliminary simulations indicate that a flap scheduler is needed to optimize control space, and the flap scheduling algorithm was enhanced to find optimal flap schedules for all wind conditions. The results of these simulations show that the influence of wind direction depends on aircraft aerodynamic characteristics, which mainly depend on the drag characteristics of the aircraft and aircraft weight. Furthermore, the results can be used to determine whether a TDDA can be executed using different aircraft and under different wind conditions.

Local danger warnings for drivers: the effect of modality and level of assistance on driver reaction

Scipedia content — Thu, 28 Jan 2021 23:12:52 +0100

Local danger warning is an important function of Advanced Driver Assistance Systems (ADAS) to improve the safety of driving. The user interface (the warning presentation) is particularly crucial to a successful danger avoidance. We present a user study investigating various warning presentations using a scenario of emergent road obstacles. Two presentation factors were selected: modality and level of assistance. The modality factor had 4 variants: speech warning, visual and speech warning, visual warning with blinking cue, and visual warning with sound cue. The level of assistance varied between with or without action suggestions (AS). In accordance with the ISO usability model, a total of 6 measurements were derived to assess the effectiveness and efficiency of the warnings and the drivers' satisfaction. Results indicate that the combination of speech and visual modality leads to the best performance as well as the highest satisfaction. In contrast, purely auditory and purely visual modalities were both insufficient for presenting high-priority warnings. AS generally improved the usability of the warnings especially when they were accompanied by supporting information so that drivers could validate the suggestions.

Multi Sector Planning Tools for Trajectory-Based Operations

Scipedia content — Thu, 28 Jan 2021 22:53:38 +0100

This paper discusses a suite of multi sector planning tools for trajectory-based operations that were developed and evaluated in the Airspace Operations Laboratory (AOL) at the NASA Ames Research Center. The toolset included tools for traffic load and complexity assessment as well as trajectory planning and coordination. The situation assessment tools included an integrated suite of interactive traffic displays, load tables, load graphs, and dynamic aircraft filters. The planning toolset allowed for single and multi aircraft trajectory planning and data communication-based coordination of trajectories between operators. Also newly introduced was a real-time computation of sector complexity into the toolset that operators could use in lieu of aircraft count to better estimate and manage sector workload, especially in situations with convective weather. The tools were used during a joint NASA/FAA multi sector planner simulation in the AOL in 2009 that had multiple objectives with the assessment of the effectiveness of the tools being one of them. Current air traffic control operators who were experienced as area supervisors and traffic management coordinators used the tools throughout the simulation and provided their usefulness and usability ratings in post simulation questionnaires. This paper presents these subjective assessments as well as the actual usage data that was collected during the simulation. The toolset was rated very useful and usable overall. Many elements received high scores by the operators and were used frequently and successfully. Other functions were not used at all, but various requests for new functions and capabilities were received that could be added to the toolset.

The Effects of Speed Uncertainty on a Separation Assurance Algorithm

Scipedia content — Thu, 28 Jan 2021 22:52:26 +0100

ources including wind prediction errors, pilot intent, surveillance errors, navigation errors and aircraft weight. The purpose of this study is to parametrically analyze the eects of aircraft speed errors on conflict detection and to analyze the performance of a conflict resolution algorithm when these speed errors are present. Results show that a speed error of 10% of the cruise speed can result in about 30% of the conflicts not being detected ten minutes before the loss of separation. It can also result in 50% more resolutions being performed to maintain separation.

Hybrid Transition Mechanism for MILSA Architecture for the Next Generation Internet

Scipedia content — Thu, 28 Jan 2021 22:40:44 +0100

MILSA (Mobility and Multihoming supporting Identifier Locator Split Architecture) (1, 2) is a new architecture to address the naming, addressing, and routing challenges in the current Internet. It separates the identifier (ID) from locator, separates control from data delivery, and provides comprehensive benefits in routing scalability, mobility and multihoming, traffic engineering, renumbering, and policy enforcements. Currently there is an on-going debate in IRTF (Internet Research Task Force) RRG (Routing Research Group) on several possible evolutional directions. Two typical directions are "core-edge separation" (called "Strategy A" (3)) and "ID locator split" (called "Strategy B") respectively. To address this issue, based on our previous work, in this paper, we present a hybrid transition and deployment mechanism to allow the two strategies to coexist and allow the architecture to evolve to any of the two directions and allow the market to decide the course of the evolution based on technical superiority, business friendliness, ease of deployability and other such factors over the long run. Further, the description of various scenarios and technical analysis show the potential benefits of this hybrid transition and deployment design in supporting long-term evolution and incremental deployability that are important for the Next Generation Internet architecture.

Pipeline Shore Approach Design: Case Study

Scipedia content — Thu, 28 Jan 2021 22:27:58 +0100

n insight is provided into the design of a large diameter high pressure gas pipeline shore approach for an LNG project off the coast of North Western Australia. The shore approach is located in a challenging and congested area, within one of Australia’s busiest ports. In close proximity to the pipeline route are two existing high pressure gas pipelines, several major shipping channels, a large spoil ground and environmentally sensitive coral reefs. Throughout the design process, careful consideration has been given to environmental and heritage constraints. In the case of the pipeline shore approach, prevention of coral mortality due to dredging induced turbidity has been a key priority. Ensuring the preservation of the heritage site adjacent to the landfall site has also been a major consideration. This paper describes the numerous challenges faced in designing the pipeline shore approach. A description of the design processes used to develop the secondary stabilisation and accidental external impact designs is provided. The unique methods employed to install the trunkline system across an operating shipping channel are also described. The information provided in this paper can be applied to the design and development of numerous pipeline shore approaches in the future. Individuals interested in pipeline secondary stabilisation, impact protection, shore crossings and pipelay techniques will also find this paper of value. This paper contributes to the technical knowledge base of the offshore industry by displaying the benefits of effectively combining relevant theoretical approaches with state of the art physical model testing methods and best practice installation techniques. This work demonstrates how innovative design practices can be successfully applied to produce a safe, cost effective and robust pipeline shore approach design in a challenging area.Copyright © 2011 by ASME

A Sectorization Method for Dynamic Airspace Configuration

Scipedia content — Thu, 28 Jan 2021 22:21:19 +0100

The Dynamic Airspace Configuration (DAC) concept requires strategically organizing and efficiently allocating airspace. In the current National Airspace System (NAS), sector boundaries have been developed heuristically over decades in light of historical data and analysis. In our previous efforts, a graph model based on air route structure was developed to model the en-route airspace over the U.S., and was partitioned using a spectral clustering algorithm. This paper addresses how to generate sectors with desirable geometry using the partitioned graph as an input. The minimum distance constraints are considered in our twostep algorithm. Instead of converting these constraints into a mathematical programming problem as most previous research has done, we treat the constraints satisfaction as a geometric problem. In correspondence to vertices assignments, an algorithm is first proposed that aims to compute non-overlapping convex hulls, while satisfying the constraints. Then, we develop a novel method using the shortest path searching algorithm to create smooth sector boundaries outside the convex hulls, where the desirable boundary is mathematically defined and computed. Finally, the performance of the proposed sectorization algorithm is demonstrated using the Enhanced Traffic Management System (ETMS) air traffic data.

A system of models for signal setting design of a signalized road network in evacuation conditions

Scipedia content — Thu, 28 Jan 2021 22:20:26 +0100

Signal control is considered an effective strategy to increase network capacity and to mitigate congestion. This paper will propose a system of models and procedures for the signal setting design of signalized intersections in a road transport network with endogenous estimation of origin-destination path flows. The system of models and procedures is able to support signal setting design for a road transport network both in ordinary and evacuation conditions.

Emission tests in city buses under real road conditions

Scipedia content — Thu, 28 Jan 2021 22:14:07 +0100

This paper will present the results of real road emission measurements performed under real traffic conditions in the city of Poznan. The tests were carried out in the morning and afternoon hours. The conditions were pre-selected so as to ensure the highest possible reflection of the actual traffic conditions: passenger count on a given bus route that would reflect typical parameters for the Poznan routes. The tests were carried out over a period of two days (Friday, Saturday) characteristic of a very small and very high passenger count and high and medium traffic congestion. The objects of the tests were the buses manufactured by Solaris: one of the vehicles was fitted with a hybrid engine (Hybrid H18) and the other operated on a conventional drive train. The buses were selected based on their similarities in terms of passenger capacity and length. They were selected to enable a comparison of their functionality and environment friendliness under real road conditions (the engines complied with the Euro V standard).

Raw Sewage through Steel Pipe: A Unique Application on the Pima County Plant Interconnect

Scipedia content — Thu, 28 Jan 2021 22:13:50 +0100

The Regional Optimization Master Plan (ROMP) is the largest capital improvements program in the history of Pima County Regional Wastewater Reclamation Department (PCRWRD), Arizona, valued at over $720 million in construction, project management and inspection services. One phase of this major undertaking, the ROMP Plant Interconnect Project, consisted of a 5-mile pipeline, with two wash crossings, connecting two metropolitan treatment facilities. Two parallel siphon structures across two wash crossings had to meet more stringent regulatory requirements than the gravity sewer itself. During the Value Engineering stage, welded steel pipe (WSP) was identified as an acceptable material substitution to ductile iron pipe (DIP) for the two siphons. The use of WSP enabled the Owner to meet and/or exceed the performance requirements for strength and corrosion protection of the Arizona State Rule governing the design of sanitary sewers. After reviewing the rigorous testing performed on polyurethane as a dielectric barrier against corrosion, the PCRWRD approved the use of WSP, lined and coated with polyurethane, for the project siphon crossing application. The two parallel steel pipelines were buried at depths of 30 feet, and the use of lap-welded joints provided a fully restrained piping system. A portion of the funding for this project came from the stimulus package provided as part of the American Recovery and Reinvestment Act (ARRA). This paper presents project details, and descriptions of the processes for adopting an alternate pipe material, the justification for selecting WSP over DIP, qualification of the dielectric coating and lining system, and challenges in the design and construction of the deep parallel siphons.

Future strategies for airports

Scipedia content — Thu, 28 Jan 2021 21:54:15 +0100

International audience; In air transport, the evolution of traffic depends upon many economic factors, and on the way in which the markets participants respond to those factors. Although airlines are the main actors, the airports are by no means passive, and their strategies will also have an impact on airline behaviour and route development. Our methodology analyzes the potential evolution of airport strategies in the next decade and its impact on the distribution of traffic at airports, using a typology of airports that has been designed for this purpose. It shows in particular that diversification strategies, which are usually reserved for large firms, can also be successfully applied to smaller airports.

A multiple-derivative and multiple-delay paradigm for decentralized controller design: uniform-rank systems

Scipedia content — Thu, 28 Jan 2021 21:53:35 +0100

Decentralized feedback systems have long been of interest to the controls community [2], [3], [20]. In recent years, research in decentralized control has been re-invigorated by interest in such applications as cooperative control of autonomous vehicle teams, data fusion in sensor networks, air traffic management, and virus-spreading control, among many others, see the overviews [15]–[18] and also e.g. the articles [6], [19], [23]. These numerous network-control applications are widely varied: they have vastly different scales, may consist of autonomous-but-sensing agents (like vehicle teams) or may be hardwired (like electric power systems), and require a wide array of control and/or algorithmic capabilities. What these varying applications make clear, however, is that new tools for designing decentralized controllers are badly needed: ones that permit highly limited components subject to delay and variation to complete intricate tasks by exploiting the network's topological structure. As the need for topology-exploiting decentralized controllers has become clear, efforts to understand the role of a network's topology in its dynamics upon control have been initiated, but the core design problem remains to be addressed.

Improved visibility of road scene images under heterogeneous fog

Scipedia content — Thu, 28 Jan 2021 21:43:33 +0100

One source of accidents when driving a vehicle is the presence of homogeneous and heterogeneous fog. Fog fades the colors and reduces the contrast of the observed objects with respect to their distances. Various camera-based Advanced Driver Assistance Systems (ADAS) can be improved if efficient algorithms are designed for visibility enhancement of road images. The visibility enhancement algorithm proposed in [1] is not dedicated to road images and thus it leads to limited quality results on images of this kind. In this paper, we interpret the algorithm in [1] as the inference of the local atmospheric veil subject to two constraints. From this interpretation, we propose an extended algorithm which better handles road images by taking into account that a large part of the image can be assumed to be a planar road. The advantages of the proposed local algorithm are its speed, the possibility to handle both color images or gray-level images, and its small number of parameters. A comparative study and quantitative evaluation with other state-of-the-art algorithms is proposed on synthetic images with several types of generated fog. This evaluation demonstrates that the new algorithm produces similar quality results with homogeneous fog and that it is able to better deal with the presence of heterogeneous fog.

A model to estimate road transport emissions from the entire life cycle

Scipedia content — Thu, 28 Jan 2021 21:32:37 +0100

This paper will discuss how road transport is the most relevant source of Green House Gas (GHG) emissions in developed countries. To achieve global emission reductions in this sector it is necessary to take into account the life cycle of each technology. Therefore, policy makers need tools to compare policies and measures in terms of emissions in their life cycle. In this study, a methodology to account GHG emissions from life cycle for a vehicle fleet (e.g. from a country, a company, a city, etc.) was developed. Moreover, a software tool called GlobalTRANS was designed and built to compute emissions from the fleet. It improves a previous tool called EmiTRANS that estimated only exhaust emissions (Tank-to-Wheel) incorporating Well-to-Tank and vehicle manufacturing emissions. GlobalTRANS calculates and sums up emissions in terms of CO2 equivalent. Default coefficients have been calculated for Spain but this tool allows users to change the coefficients and substitute them. Finally, the methodology has been successfully tested for the calculation of several fleets and pathways and results were compared with other Life Cycle Assessments (LCA). This paper presents an example from a diesel Euro 4 light duty vehicle showing that vehicle use means 79% of total emissions, while diesel production accounts for 13% and vehicle manufacture for 8%.

Green approaches without trade-off: Final results from the FAGI-project

Scipedia content — Thu, 28 Jan 2021 21:31:22 +0100

fundamental contribution to satisfying future demands in air transport like gain of capacity, reduction of environmental impact, improved flight efficiency and high predictability is often the term “4D”. However, having a look at today's fleet only one out of nine aircraft is currently able to, e.g., fulfill a requested time of arrival with high accuracy. Therefore, a successful transition to a 4D-trajectory based operations strongly depends on how especially the unequipped aircraft without an onboard flight management system fit into the concept. In 2007–2009, the FAGI (Future Air Ground Integration) project investigated a new concept facilitating the transition to 4D-trajectory based air traffic management operations.

Avoiding Timing Anomalies Using Code Transformations

Scipedia content — Thu, 28 Jan 2021 21:21:51 +0100

Divide-and-conquer approaches to worst-case execution-time analysis (WCET analysis) pose a safety risk when applied to code for complex modern processors: Interferences between the hardware acceleration mechanisms of these processors lead to timing anomalies, i.e., a local timing change causes an either larger or inverse change of the global timing. This phenomenon may result in dangerous WCET underestimation. This paper presents intermediate results of our work on strategies for eliminating timing anomalies. These strategies are purely based on the modification of software, i.e., they do not require any changes to hardware. In an effort to eliminate the timing anomalies originating from the processor’s out-of-order instruction pipeline, we explored different methods of inserting instructions in the program code that render the dynamic instruction scheduler inoperative. We explain how the proposed strategies remove the timing anomalies caused by the pipeline. In the absence of working solutions for timing analysis for these complex processors, we chose portable metrics from compiler construction to assess the properties of our algorithms.

A hardware pipeline for accelerating ray traversal algorithms on streaming processors

Scipedia content — Thu, 28 Jan 2021 21:11:28 +0100

Ray Tracing is a graphics rendering method that uses rays to trace the path of light in a computer model. To accelerate the processing of rays, scenes are typically compiled into smaller spatial boxes using a tree structure and rays then traverse the tree structure to determine relevant spatial boxes. This allows computations involving rays and scene objects to be limited to only objects close to the ray and does not require processing all elements in the computer model. We present a ray traversal pipeline designed to accelerate ray tracing traversal algorithms using a combination of currently used programmable graphics processors and a new fixed hardware pipeline. Our fixed hardware pipeline performs an initial traversal operation that quickly identifies a smaller sized, fixed granularity spatial bounding box from the original scene. This spatial box can then be traversed further to identify subsequently smaller spatial bounding boxes using any user-defined acceleration algorithm. We show that our pipeline allows for an expected level of user programmability, including development of custom data structures, and can support a wide range of processor architectures. The performance of our pipeline is evaluated for ray traversal and intersection stages using a kd-tree ray tracing algorithm and a custom simulator modeling a generic streaming processor architecture. Experimental results show that our pipeline reduces the number of executed instructions on a graphics processor for the traversal operation by 2.15X for visible rays. The memory bandwidth required for traversal is also reduced by a factor of 1.3X for visible rays.

Weight driven optimisation for vehicle propulsion determination

Scipedia content — Thu, 28 Jan 2021 20:59:42 +0100

Collection and analyses of crowd travel behaviour data by using smartphones

Scipedia content — Thu, 28 Jan 2021 20:56:16 +0100

In 2010 the MOVE project started in the collection and analysis of crowd behaviour data. The two main goals of the project are first, the collection of data through the use of mobile phones. The second goal is to develop new technologies to process and mine the collected data for crowd behaviour analysis. The technology will allow to make advanced interpretations of historic and dynamic mobile crowd data coming from GSM/GPS and from different classes of users (vehicle, pedestrian, indoor/outdoor). Fusion will be made between data coming from different sources (smartphone, navigation device) and external map data. The interpretation will allow the mining of advanced features/geometry from the crowd data as well as the dynamic (travel) behavior of the population.

Design of unknown input fuzzy observer for vehicle dynamics estimation with road geometry consideration

Scipedia content — Thu, 28 Jan 2021 20:43:04 +0100

methodology for estimating vehicle dynamics whith road geometry consideration is presented in this paper. Vehicle sideslip and roll parameters are estimated in the presence of the road bank angle and the road curvature as unknown inputs. The unknown inputs are then estimated using the observer results. This information about the road geometry and vehicle parameters is needed in the driver assistance systems to be able to calculate the risk index of a rollover or a lane departure crashes. Taking into account the unmeasured variables, an unknown inputs (TS) observer is then designed on the basis of the measure of the roll rate, the steering angle and the lateral offset given by the distance between the road centerline and the vehicle axe at a look-ahead distance. Synthesis conditions of the proposed fuzzy observer are formulated in terms of Linear Matrix Inequalities (LMI) using Lyapunov method. Simulation results show good efficiency of the proposed method to estimate both vehicle dynamics and road geometry.

Safety arguments for next generation location aware computing

Scipedia content — Thu, 28 Jan 2021 20:42:48 +0100

Concerns over the accuracy, availability, integrity and\\ud continuity of Global Navigation Satellite Systems (GNSS)\\ud have limited the integration of GPS and GLONASS for\\ud safety-critical applications. More recent augmentation\\ud systems, such as the European Geostationary Navigation\\ud Overlay Service (EGNOS) and the North American Wide\\ud Area Augmentation System (WAAS) have begun to address\\ud these concerns. Augmentation architectures build on the\\ud existing GPS/GLONASS infrastructures to support locationbased services in Safety of Life (SoL) applications. Much of the technical development has been directed by air traffic management requirements, in anticipation of the more extensive support to be offered by GPS III and Galileo. WAAS has already been approved to provide vertical guidance against ICAO safety performance criteria for aviation applications. During the next twelve months, we will see the full certification of EGNOS for SoL applications.\\ud This paper identifies strong similarities between the safety\\ud assessment techniques used in Europe and North America.\\ud Both have relied on hazard analysis techniques to derive\\ud estimates of the Probability of Hazardously Misleading\\ud Information (PHMI). Later sections identify significant\\ud differences between the approaches adopted in application\\ud development. Integrated fault trees have been developed by\\ud regulatory and commercial organisations to consider both\\ud infrastructure hazards and their impact on non-precision\\ud RNAV/VNAV approaches using WAAS. In contrast,\\ud EUROCONTROL and the European Space Agency have\\ud developed a more modular approach to safety-case\\ud development for EGNOS. It remains to be seen whether the\\ud European or North American strategy offers the greatest\\ud support as satellite based augmentation systems are used\\ud within a growing range of SoL applications from railway\\ud signalling through to Unmanned Airborne Systems. The key\\ud contribution of this paper is to focus attention on the safety\\ud arguments that might support this wider class of location\\ud based services.

Visual confirmation of mobile objects tracked by a multi-layer lidar

Scipedia content — Thu, 28 Jan 2021 20:40:32 +0100

International audience; Integrity of the information provided by a perception system is crucial for advanced driver assistance systems intended for safety applications, like obstacle avoidance systems. A method to ensure integrity is to use different kinds of perception sources. Lidars are key sensors for multiple objects detection and tracking. Stereo vision systems (SVS) can be used to improve the tracking but, in this paper, we use also SVS to confirm the real existence of potential obstacles thanks to 3D dense reconstruction in focused regions of interest. Synchronization issues between the different sensors are addressed using predictive filtering. The proposed approach is evaluated in real conditions thanks to five use cases relevant to urban situations. Results show that this visual confirmation strategy is efficient.

Lessons Learned in Operational Space and Air Traffic Management

Scipedia content — Thu, 28 Jan 2021 20:37:22 +0100

Since the STS-114 mission in August of 2005, the FAA has partnered with NASA to protect aircraft flying in the National Airspace System from the potential hazards associated with a catastrophic failure of a reentering Space Shuttle orbiter, similar to that which occurred during STS-107 in February of 2003. This work has produced a set of procedures and tools for use before and during the reentry to provide FAA air traffic managers and controllers with increased situational awareness. An initial approach was implemented for STS-114 based on the need to maximize the time for the FAA to react to an orbiter failure. This approach has evolved over time through the identification of lessons learned on subsequent flights and the subsequent development of additional requirements to address them. This includes the development of the Shuttle Hazard Area to Aircraft Calculator (SHAAC), a dedicated tool for use in both reentry planning and real-time modes. This paper describes some of those key lessons and the approaches taken to address them. Emphasis is placed on those lessons that resulted from specific air traffic management needs. Many of the lessons learned to date have been captured as requirements for a next-generation FAA tool that will provide similar capabilities during the planning and operational phases of the launches and reentries of future commercial space vehicles. Future commercial space operators and air traffic managers in other organizations may find these lessons useful in the development of future tools to support their space and air traffic safety needs. N the spring of 2005, the Federal Aviation Administration (FAA) began investigating the use of existing air traffic tools to establish Temporary Flight Restrictions (TFRs) for protecting aircraft from the potential hazards of a NASA Space Shuttle orbiter failure during the planned reentry of the “Return to Flight” (STS114) mission. This work was initiated from a recommendation of the Columbia Accident Investigation Board (CAIB), which highlighted the potential risks to aircraft from the hazards of falling spacecraft debris using data from a study of the Space Shuttle Columbia (STS-107) accident 1 . Although a number of procedures for FAA support of Shuttle operations were in existence prior to this accident, these procedures did not take into account the potential hazards to aircraft of falling Shuttle debris during a planned reentry. In the process of this investigation, several approaches to airspace management were considered. Each approach relied on the same key capabilities in its formulation: the ability to accurately model a Shuttle reentry accident, the ability to identify the potentially affected airspace, and the ability to assess the potential impacts on the air traffic in the National Airspace System (NAS). This paper describes the new tools that were developed and the existing tools that were modified to provide FAA air traffic managers with these capabilities. The method by which these tools were used to identify the ultimate approach and the airspace management plan that has been in place since the STS-114 reentry are also discussed. Further, insight gained in the preparation for STS-114 and the operational experience gained in subsequent missions has yielded a number of lessons learned that have been applied to the FAA’s support of subsequent Shuttle flights. Many of these lessons learned will apply to the operations of future commercial launch and reentry vehicles that will transit the NAS on their way to and from space.

Plug-in vehicles for Smart Grids: what can and cannot be done with existing technology

Scipedia content — Thu, 28 Jan 2021 20:29:38 +0100

There is much interest regarding the future possibilities - and risks - arising from integrating increasing numbers of plug-in vehicles with power system network operations, in particular demand-side management. There has been comparatively less enthusiasm directed towards addressing the question of what can and cannot be done with existing technology. This paper discusses what could be achieved and implemented using present technology only and a little innovative thinking - ‘recharging regimes’ - and discusses the limitations of these approaches.

Nonlinear state-dependent delay modeling and stability analysis of internet congestion control

Scipedia content — Thu, 28 Jan 2021 20:20:53 +0100

International audience; It is shown that the queuing delay involved in the congestion control algorithm is state-dependent and does not depend on the current time. Then, using an accurate formulation for buffers, networks with arbitrary topologies can be built. At equilibrium, our model reduces to the widely used setup by Paganini et al. Using this model, the delay-derivative is analyzed and it is proved that the delay time-derivative does not exceed one for the considered topologies. It is then shown that the considered congestion control algorithm globally stabilizes a delay-free single buffer network. Finally, using a specific linearization result for systems with state-dependent delays from Cooke and Huang, we show the local stability of the single bottleneck network.

Human-In-the-Loop Evaluation of NextGen Concepts in the Airspace Operations Laboratory

Scipedia content — Thu, 28 Jan 2021 20:13:57 +0100

The Airspace Operations Laboratory (AOL) at the NASA Ames Research Center hosts a powerful simulation environment for human-in-the-loop studies of air traffic operations. The primary real-time simulation capabilities are developed by the AOL development team as part of the Multi Aircraft Control System (MACS) and cover a wide range of operational environments from current day operations to future operational concepts like those envisioned for the Next Generation Air Transportation System (NextGen). The research focus in the AOL is on examining air traffic control and traffic management operations across multiple air traffic control sectors and Centers in rich air/ground environments that can include oceanic, enroute and terminal airspace. The basic simulation capabilities and earlier research was presented at the AIAA Modeling and Simulation Technologies conference in 2006. Since then, the AOL capabilities have been continuously improved and expanded. Over the past four years the AOL has been extensively utilized to investigate a variety of NextGen concepts for NASA’s NextGen Airspace Program and the FAA’s Air Traffic Organization for Planning, Research and Technology. The primary focus areas under investigation in the AOL are Separation Assurance and the associated Functional Allocation for NextGen, Controller Managed Spacing for nearto mid-term Terminal area operations, flow-based trajectory management and multi-sector planning and dynamic airspace configuration and flexible airspace management. This paper first gives an overview over the most significant capabilities that were added since 2006 and then reviews at a high level the main activities and findings in the different research focus areas.

Variable speed limits for area-wide reduction of emissions

Scipedia content — Thu, 28 Jan 2021 20:13:38 +0100

hough traffic congestion is a pressing problem that drivers face every day, improving the traffic flow does not always create a healthy environment to the people residing in the neighborhood of the freeway. Improved traffic flow neither means efficient fuel consumption of the vehicles. Moreover, reduction of total emissions or travel times in a traffic network does not always guarantee reduction in the area-wide emission levels, because there are many other factors that affect the area-wide emissions. In particular, the direction and speed of wind are important factors that play a significant role in the area-wide emission levels. Therefore, in this paper, we systematically model the effect of wind on the area-wide emission levels and design a model-based traffic controller to reduce the dispersion of emissions. More specifically, a model predictive control (MPC) is used to integrate various variable speed limits in order to provide a balanced trade-off between the area-wide emissions and the travel times. Furthermore, we present a case study to demonstrate the proposed control approach.

Pollution of drinking water transported by corroded metallic pipelines

Scipedia content — Thu, 28 Jan 2021 20:11:03 +0100

Corrosion of metallic water pipelines is a function of the pipe’s surrounding environment (soil and water). This means that it is important to know the physical and chemical characteristics of the pipe’s surrounding environment. The corrosion of externally unprotected metallic water pipelines, particularly ductile iron pipes, in localities with aggressive soil conditions is becoming a significant problem: repair and replacement costs are high, and failures cause supply interruptions to customers and inconvenience to the public. Anti-corrosive protection for metallic water pipelines, their fittings and accessories is very important, because they may be attacked by corrosion with time. The tendency of a metallic substrate to corrode is a function of the surface characteristics of the metal and of the metal/protective film interface, the physical, electrical and electrochemical properties of the film, and the nature of the environment in which the pipelines system is placed. In this work the authors have looked at the corrosion problems of metallic water pipelines and their control. The corrosive properties of water and soil environments are reviewed. Parameters affecting corrosion are discussed. The pollution of drinking water transported by metallic pipes caused by corrosion is discussed. The purpose of this work is to provide guidelines for materials selection in water and soil environments, and how the water pipelines can be protected against metallic corrosion.

A realistic simulator for the design and evaluation of intelligent vehicles

Scipedia content — Thu, 28 Jan 2021 19:55:37 +0100

The number of vehicles hitting the road each day is rapidly increasing, and several problems, such as traffic conges- tion or driver safety, can no longer be solved in the same fashion as before. Intelligent transportation systems could potentially solve part of these problems, but prototyping, designing and testing cooperative smart vehicles is a cumbersome task. This paper presents a realistic simulator, capable of operating both at microscopic and sub-microscopic level, where intelligent vehicles can be designed and analyzed with a pragmatic approach. A number of advances in robotics have already been transferred to vehicular technology, with a potential increase of this trend into the future. Here, we develop a plugin for a well-established robotics simulator (Webots), in order to reinforce at the virtual level this cross-fertilization between the two areas and create a baseline for realistic studies of future solutions in real intelligent vehicles.

Simulations of Credits Concept with User Input for Collaborative Air Traffic Management

Scipedia content — Thu, 28 Jan 2021 19:40:55 +0100

This paper describes the procedure and outcome of a human-in-the-loop simulation experiment. The purpose of the simulation was to study feasibility of incorporating user flight preferences in air traffic demand and capacity management. Five airline dispatchers specified flight priorities for multiple routes. These priorities were used for airspace constraint management by creating a new credit ranked flight departure schedule. One air traffic manager prescribed and managed the airspace constraints. The dispatchers were trained on the system using different traffic scenarios. A realistic data set with convective weather was used for generating final results. Based on the experiment results, the credits concept allowed users to prioritize their flights and to distribute delays as per their preference. It was also observed that the delays could be reduced and better distributed among users with respect to a first-come-first served schedule, without violating airspace constraints. The study elicited several factors for prioritizing flights from the users’ perspective, which could be used in future fast-time simulations.

Hydrate Formation and its Influence on Natural Gas Pipeline Internal Corrosion Rate

Scipedia content — Thu, 28 Jan 2021 19:26:31 +0100

This study establishes the ability of hydrate formation to initiate internal corrosions along natural gaspipelines. The identified corrosion types, which are cavitations, erosion and corrosions by chemicalreactions,arecapabletoindividuallyorcollectivelyinitiatepittingandstresscracking corrosionswhicharealso dangerous to gas pipelines. The impacts of these corrosion types are classified to economics,environmental and human loss with the economic loss as much as US$3 trillion depending on thepipe-length, location, sea depth, wave function, climatic conditions and political situations.Various predictive measures to minimize hydrate formations are finally recommended.

A Computer Simulation of the System-Wide Effects of Parallel-Offset Route Maneuvers

Scipedia content — Thu, 28 Jan 2021 19:26:04 +0100

Modernization of the current air transportation system is an ongoing, incremental process. An early step in this modernization process is the implementation of enhancements to the Federal Aviation Administration’s (FAA’s) En Route Automation Modernization (ERAM) that supports en-route controllers in managing separation. This project is called Trajectory Based Operations (TBO) Separation Management: Modern Procedures. Research supporting this project involves computer human interface improvements to ERAM’s Decision Support Tools (DSTs) post Release 3 and algorithmic enhancements to the Conflict Probe to increase the usability of the tools for the near-term time frame of NextGen. One proposed algorithmic enhancement is to enable ERAM to model parallel-ose

Analysis of Factors for Incorporating users Preferences in Air Traffic Management: A Users' Perspective

Scipedia content — Thu, 28 Jan 2021 19:24:10 +0100

This paper presents an analysis of factors that impact user flight schedules during air traffic congestion. In pre-departure flight planning, users file one route per flight, which often leads to increased delays, inefficient airspace utilization, and exclusion of user flight preferences. In this paper, first the idea of filing alternate routes and providing priorities on each of those routes is introduced. Then, the impact of varying planning interval and system imposed departure delay increment is discussed. The metrics of total delay and equity are used for analyzing the impact of these factors on increased traffic and on different users. The results are shown for four cases, with and without the optional routes and priority assignments. Results demonstrate that adding priorities to optional routes further improves system performance compared to filing one route per flight and using first-come first-served scheme. It was also observed that a two-hour planning interval with a five-minute system imposed departure delay increment results in highest delay reduction. The trend holds for a scenario with increased traffic.

Reduction of Damage and Hindrance to Wastewater Transmission Systems Caused by Air Pockets by Deployment of Air Valves

Scipedia content — Thu, 28 Jan 2021 19:17:20 +0100

Recent research studies and surveys have shown that air pockets in wastewater transmission systems cause extensive damage and hindrance. Air pockets decrease flow capacity, they induce significant head losses and energy losses, they prompt serious corrosion, and they can trigger and/or enhance pressure surges. In the advent of concern for energy conservation, more and more research is invested in studying the effect of air pockets on flow efficiency and energy consumption. Conclusions are that air pockets have a very significant impact on these, especially in wastewater force mains. Much has been written in the past about Hydrogen Sulfide corrosion in wastewater pipelines. The EPA published a number of papers, pamphlets, and reports to Congress on this subject. More and more papers and studies today, attribute Hydrogen Sulfide corrosion to air pockets, including a number of papers presented at the ASCE Pipelines 2009 Conference in San Diego. Most of these papers refer to detection, monitoring, evaluation, assessment and management of corrosion, but not of prevention. They point out the contribution of air pockets to Hydrogen Sulfide corrosion, but they do not discuss the means and ways of preventing air pocket accumulation. Though, for many years, it was commonly accepted by surge experts that air pockets dampen surges, it was determined in recent research studies that air pockets of certain sizes and in certain locations along a pipeline, can induce and/or enhance surges. These surges, especially in force mains weakened by corrosion, can cause intensive and severe damage to pipelines, resulting in soil and water source polluting leakage, and health endangering pathogen and contaminant intrusion to drinking water transmission systems.

Comparison of the Performances of Two Aggregate Air Traffic Models

Scipedia content — Thu, 28 Jan 2021 19:14:52 +0100

ght paths, the other including the entire National Airspace System. Numerical results of this study show that the Link Transmission Model achieves a same level of accuracy as Large-capacity Cell Transmission Model in air trac prediction , and the computational eciency is signicantly improved with an equally optimal solution in air trac optimization.

Genetic algorithms approach for containerships fleet management dependent on cargo and their deadlines

Scipedia content — Thu, 28 Jan 2021 18:54:26 +0100

This work proposes a method to improve the flexibility of short sea shipping and to increase its competitiveness with other means of freight transport. A logistic model and a mathematical model are developed to manage a fleet of two or more vessels which transport cargo to and from several ports, bearing in mind the cargo distribution and delivery deadlines. At each port, the model determines which port to visit next, which containers to embark, disembark and to shift, as well as how to stow them on board. In fact, this formulation brings together the fleet management problem, the container stowage problem (CSP) and the vehicle routing problem (VRP). An example scenario is set up, using generated but realistic data. The problem is then solved, in a simplified version, using a Genetic Algorithm. The results show that introducing the possibility of route changes, the overall efficiency (and thus competitiveness) of short sea shipping can be improved.

S-MATE: Secure Coding-Based Multipath Adaptive Traffic Engineering

Scipedia content — Thu, 28 Jan 2021 18:35:01 +0100

There have been several approaches to provisioning traffic between core network nodes in Internet Service Provider networks. Such approaches aim to minimize network delay, increase capacity, and enhance security services. MATE (Multipath Adaptive Traffic Engineering) has been proposed for multipath adaptive traffic engineering between an ingress node (source) and an egress node (destination). Its novel idea is to avoid network congestion and attacks that might exist in edge and node disjoint paths between two core network nodes. This paper builds an adaptive, robust, and reliable traffic engineering scheme for better performance and operation of communication networks. This will also provision quality of service (QoS) and protection of traffic engineering to maximize network efficiency. Specifically, we present a new approach, S-MATE (secure MATE) is developed to protect the network traffic between two core nodes (routers, switches, etc.) in a cloud network. S-MATE secures against a single link attack/failure by adding redundancy in one of the operational paths between the sender and receiver. The proposed scheme can be built to secure core networks such as optical and IP networks.

Recommending Social Events from Mobile Phone Location Data

Scipedia content — Thu, 28 Jan 2021 18:32:27 +0100

city offers thousands of social events a day, and it is difficult for dwellers to make choices. The combination of mobile phones and recommender systems can change the way one deals with such abundance. Mobile phones with positioning technology are now widely available, making it easy for people to broadcast their whereabouts, recommender systems can now identify patterns in people’s movements in order to, for example, recommend events. To do so, the system relies on having mobile users who share their attendance at a large number of social events: cold-start users, who have no location history, cannot receive recommendations. We set out to address the mobile cold-start problem by answering the following research question: how can social events be recommended to a cold-start user based only on his home location? To answer this question, we carry out a study of the relationship between preferences for social events and geography, the first of its kind in a large metropolitan area. We sample location estimations of one million mobile phone users in Greater Boston, combine the sample with social events in the same area, and infer the social events attended by 2,519 residents. Upon this data, we test a variety of algorithms for recommending social events. We find that the most effective algorithm recommends events that are popular among residents of an area. The least effective, instead, recommends events that are geographically close to the area. This last result has interesting implications for location-based services that emphasize recommending nearby events.

Traffic and CO2 emissions of urban goods deliveries under contrasted scenarios of retail location and distribution

Scipedia content — Thu, 28 Jan 2021 18:16:44 +0100

International audience; This communication presents four contrasted and near-caricatured scenarios of retail location and distribution, and compares them on the bases of both road occupancy rates and greenhouse gas emissions. Two main families of scenarios are defined: retailing land-use scenarios, based on the location of the different retailing activities of a city, and end-consumer delivery organisational scenarios, based on the definition of new services to deliver end-consumers, at home or to reception points. Those scenarios are simulated using an integrated approach combining inter-establishement goods transport flows, shopping trips and end-consumer deliveries. The simulation approach is able to show the relation between several aspects of retailing deployment (store location, catchment area's supply, urban retailing planning policies) and both upstream distribution of goods to retailers and downstream usage of private vehicles for shopping. Although scenarios are extreme and near-caricatured, they are able to identify the limits and forces of the different retailing strategies in urban zones.

Dynamically Evolving Sectors for Convective Weather Impact

Scipedia content — Thu, 28 Jan 2021 18:15:55 +0100

new strategy for altering existing sector boundaries in response to blocking convective weather is presented. This method seeks to improve the reduced capacity of sectors directly affected by weather by moving boundaries in a direction that offers the greatest capacity improvement. The boundary deformations are shared by neighboring sectors within the region in a manner that preserves their shapes and sizes as much as possible. This reduces the controller workload involved with learning new sector designs. The algorithm that produces the altered sectors is based on a force-deflection mesh model that needs only nominal traffic patterns and the shape of the blocking weather for input. It does not require weather-affected traffic patterns that would have to be predicted by simulation. When compared to an existing optimal sector design method, the sectors produced by the new algorithm are more similar to the original sector shapes, resulting in sectors that may be more suitable for operational use because the change is not as drastic. Also, preliminary results show that this method produces sectors that can equitably distribute the workload of rerouted weather-affected traffic throughout the region where inclement weather is present. This is demonstrated by sector aircraft count distributions of simulated traffic in weather-affected regions.

Discussion Paper on the Use of FPC’s C240 Integrated Compressed Natural Gas (ICNG) Storage Units and TransCanada’s CNG Storage System for the Storage of Natural Gas As a Fuel for Marine Applications

Scipedia content — Thu, 28 Jan 2021 18:08:46 +0100

This discussion paper is based on a preliminary design and is not to be construed or interpreted as being a suitable basis for adoption as a final design for natural gas storage facilities or marine vessels. The gas storage concepts were developed as a basis for project budgeting, further design studies such as HAZID/HAZOP/FEMA, and for review/comment by Classification Societies and Regulatory Authorities as a precedent to further design development. The contents, comments and opinions contained herein are proprietary to Floating Pipeline Company Incorporated and TransCanada."/jats:p" "jats:p"Paper published with permission.

Scheduling Suspendable, Pipelined Tasks with Non-Preemptive Sections in Soft Real-Time Multiprocessor Systems

Scipedia content — Thu, 28 Jan 2021 17:56:09 +0100

While most prior work on multiprocessor real-time scheduling focuses on independent tasks, dependencies due to non-preemptive sections, suspensions, and pipeline-based precedence constraints are common in practice. In this paper, such complexities are considered in the context of the global earliest-deadline-first scheduling algorithm. It is shown that any periodic task system with such dependencies can be transformed into one with only suspensions in a way that preserves maximum per-task response times. This result enables analysis directed at systems with suspensions to be applied if non-preemptive sections and/or pipelines are present as well.

A pairing algorithm for landing aircraft to closely spaced parallel runways

Scipedia content — Thu, 28 Jan 2021 17:49:28 +0100

To facilitate pairing of aircraft while meeting a schedule, the pair-scheduling problem for landing aircraft in Very Closely Spaced Parallel Approaches was studied. An earlier prototype was adopted and the scheduling algorithm was extended in several ways to improve the solution quality and expand the range of constraints it could handle. This paper presents the scheduling problem formulation, as well as enhancements made to an earlier prototype that made it suitable for application in a human-in-the-loop simulation carried out recently at NASA Ames Research Center. Experimental data from the simulations as well as an extensive set of stress tests are analyzed and discussed. Results suggest the algorithm succeeded in suggesting aircraft pairs acceptable to the air traffic controllers in over 97% of the cases. Evaluating the performance and scalability characteristics of the algorithm demonstrates its effectiveness in discovering feasible aircraft pairs that meet all the sequencing, separation, pair-group, and runway assignment constraints. Overall, the high solution quality and short runtime makes the proposed algorithm a suitable and attractive candidate for use in a real-time aircraft-pairing application.

Study for sustainable traffic strategy in local government perspective: a contribution towards a strategy for mobility

Scipedia content — Thu, 28 Jan 2021 17:43:16 +0100

The sustainable development of cities is one of the main concerns in territorial planning and management. Mobility and accessibility are two essential areas for balanced development in urban areas. This paper aims to bring an awareness of mobility and accessibility to the transport problems in the Cascais area where the movements of the population cause traffic problems. This project offers alternatives solutions to public collective transport using innovative solutions supported with the use of new technology. Mobility in the urban areas is a key factor in sustainable development and obtaining feasible economic and social cohesion.

Analysis of Air Traffic Controller Workload Reduction Based on the Solution Space for the Merging Task

Scipedia content — Thu, 28 Jan 2021 17:39:57 +0100

traffic controller workload is considered to be an important limiting factor to the growth of air traffic. The difficulty of an air traffic control task can be analyzed through examining the problem’s solution space, that is, all possible vector commands that satisfy the constraints of safety, productivity and efficiency. But apart from deriving metrics for workload, a visualization based on the solution space, resulting in the Solution Space Diagram, could help the controller inmanaging the air traffic. An experiment was conducted in which two different levels of traffic density were tested in order to evaluate the effects of presenting the Solution Space Diagram on controller workload. The experiment entailed the task of merging aircraft into a single route and subjects provided subjective ratings of workload at fixed intervals of time. Depending on traffic level and subject experience, significant effects of the Solution Space Diagram were found on the reduction of controller workload.

Controller-Managed Spacing - A Human-In-The-Loop Simulation of Terminal-Area Operations

Scipedia content — Thu, 28 Jan 2021 17:38:48 +0100

human-in-the-loop simulation investigated how well terminal-area air traffic controllers could manage arrival traffic flying optimized profile descents on RNAV/RNP routes, while maintaining high throughput under varying environmental conditions. Scenarios were investigated with and without advisory tools and improved displays, and also examined how well controllers could cope with off-nominal situations such as ties at merge points. The role of an arrival management planner responsible for issuing path changes to aircraft upon entry to the terminal area was also investigated. The results show that in the tools condition, controllers kept aircraft on their routes while maintaining similar throughput levels to the no-tools condition. Route deviations occurred in the no-tools condition. While the absence of advanced tools resulted in slightly higher workload, the average controller workload ratings were low for both the no-tools and tools conditions. With the currently implemented advisory tools and displays, participant controllers in both conditions were able to absorb approximately one minute of delay with speed adjustments alone. This work is part of ongoing research on operations in super-density terminal airspace.

A Comparison of the Street Networks of Navteq and OSM in Germany

Scipedia content — Thu, 28 Jan 2021 17:27:19 +0100

In Germany, the data of the Open Street Map project has become available as an alternative to proprietary road networks in commercial business geomatics software, and their customers are wondering whether the quality may be sufficient. This paper describes an implemented methodology to compare OSM street data with those of Navteq for all populated roads in Germany. As a unique feature, the presented methodology is based on a matching between the street objects of OSM and Navteq, and all steps are fully automated so that they can be applied to updated versions of both data sets. While there are considerable qualitative differences between regions, towns, and street categories, at a national level the relative completeness of objects, their relative precision and the relative completeness of names are high enough for maps. However, other attributes, which are needed for the computation of catchment areas, are still relatively incomplete.