Documents published in 1999 : Scipedia

THE DIFFERENCES OF DRIVING BEHAVIOR AMONG DIFFERENT DRIVER AGE GROUPS AT SIGNALIZED INTERSECTIONS
J. Pernia, J. Lu

Collection of open articles in transport research (2000). Vol. 2000, 6

Abstract
Over the past few years the population of older drivers has substantially increased across the United States. Older drivers are a group of special interest because of their potential age-related deficiencies. It is essential to understand their driving behavior and adjust the conditions of roadway systems according to their requirements. Likewise, driving behavior of older drivers needs to be considered in order to adequately estimate capacities at intersections. In the past few years, research projects were performed by the University of South Florida to analyze the differences of driving behavior among different driver age groups. Typically, the driving behavior of older drivers was evaluated by analyzing their start-up lost time and saturation headway at signalized intersections as compared to young and mid-age driver groups. Research results were based on data collected from signalized intersections with different land-use types. These intersections are located in west and central Florida where the elderly population has been increasing rapidly in recent years. From the results it was found that the presence of older drivers significantly reduced intersection capacity at all study sites because of their higher lost times and lower saturation flow rates. Therefore, driving behavior of older drivers should be considered in designing intersections located in places with a significant older driver population. In the research, models were developed to predict start-up lost time and saturation headway values generated by older drivers. Then, the variation in capacities with an increasing percentage of older drivers in the traffic stream was modeled. Finally, adjustment factors for different percentages of older drivers were developed to adjust intersection capacity. These factors are believed to account for the presence of older drivers in the traffic stream. The adjustment factors may be used in capacity analysis and design procedures for intersections with a significant older driver population. Document type: Article
Abstract
Over the past few years the population of older drivers has substantially increased across the United States. Older drivers are a group of special interest because of their [...]
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TRAFFIC MANAGEMENT SYSTEM AGAINST MAJOR EARTHQUAKES
Y. Iida, H. Shimada, F. Kurauchi

Collection of open articles in transport research (2000). Vol. 2000, 5

Abstract
This paper describes fundamental issues of the traffic management systems and the actual traffic conditions following the Hanshin-Awaji Earthquake. Based on these issues, a new concept of traffic management system against an earthquake disaster is proposed, and the effectiveness of 2-stage area traffic regulation is examined through the case study for accommodation of personal passenger car demand immediately after the earthquake. Additionally an integrated traffic management system against a major earthquake and the related issues are discussed. It is expected that ITS technology will play an important role in the future development of traffic management system during an earthquake disaster. Document type: Article
Abstract
This paper describes fundamental issues of the traffic management systems and the actual traffic conditions following the Hanshin-Awaji Earthquake. Based on these issues, [...]
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An expert judgment model applied to estimating the safety effect of a bicycle facility
L. Leden, U. Pulkkinen, P. Gårder

Collection of closed articles in transport research (2000). Vol. 2000, 9

Abstract
This paper presents a risk index model that can be used for assessing the safety effect of countermeasures. The model estimates risk in a multiplicative way, which makes it possible to analyze the impact of different factors separately. Expert judgments are incorporated through a Bayesian error model. The variance of the risk estimate is determined by Monte-Carlo simulation. The model was applied to assess the safety effect of a new design of a bicycle crossing. The intent was to gain safety by raising the crossings to reduce vehicle speeds and by making the crossings more visible by painting them in a bright color. Before the implementations, bicyclists were riding on bicycle crossings of conventional Swedish type, i.e. similar to crosswalks but delineated by white squares rather than solid lines or zebra markings. Automobile speeds were reduced as anticipated. However, it seems as if the positive effect of this was more or less canceled out by increased bicycle speeds. The safety per bicyclist was still improved by approximately 20%. This improvement was primarily caused by an increase in bicycle flow, since the data show that more bicyclists at a given location seem to benefit their safety. The increase in bicycle flow was probably caused by the new layout of the crossings since bicyclists perceived them as safer and causing less delay. Some future development work is suggested. Pros and cons with the used methodology are discussed. The most crucial parameter to be added is probably a model describing the interaction between motorists and bicyclists, for example, how risk is influenced by the lateral position of the bicyclist in relation to the motorist. It is concluded that the interaction seems to be optimal when both groups share the roadway.
Abstract
This paper presents a risk index model that can be used for assessing the safety effect of countermeasures. The model estimates risk in a multiplicative way, which makes it [...]
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The competitive advantage of seaports
A. Struyf, P. Rousseeuw, G. Pison, A. Verbeke, E. Haezendonck

Collection of closed articles in transport research (2000). Vol. 2000, 8

Abstract
This article aims to identify empirically the most important location advantages determining the port of Antwerp's competitive position for containers and conventional cargo as compared to its main rivals in the Hamburg-Le Havre range. A conceptual framework is developed for analysing the competitiveness of seaports, based on an extended version of Porter's ‘diamond’ approach. This framework is tested through a large scale survey with port operators and experts. This article suggests that the port of Antwerp largely benefits from the superstructure used by forwarders, the flexibility and the productivity of its dockworkers and its forwarders. The analysis also identifies three key disadvantages, namely the weak competitiveness of pilotage and inland navigation service providers in the port of Antwerp, and the limited maritime accessibility of the port. The introduction of the extended ‘diamond’ framework allows the identification of a set of strengths and weaknesses characterising a specific port cluster and can thus contribute substantially to the development of port policy and management.International Journal of Maritime Economics (2000) 2, 69–82; doi:10.1057/ijme.2000.8
Abstract
This article aims to identify empirically the most important location advantages determining the port of Antwerp's competitive position for containers and conventional cargo [...]
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New waves in transportation in North-Eastern Europe
V. Himanen

Collection of closed articles in transport research (2000). Vol. 2000, 7

Abstract
North‐Eastern Europe is a peripheral area around the Baltic Sea. In some parts i.e. Scandinavia high living standards including developed transport systems exist when at the same time rapid changes in the way of living in other parts ‐ Poland, the Baltic Countries and Russia ‐ are ongoing. Transport policies in the European Union are caught between demands for improved mobility and the concern on the environmental protection. In the former socialist countries the environmental issues are subdued by the demands for efficient transport. A fixed road and rail connection between Denmark and Sweden will change the transport geography of the western part of the area. Also the integration of the Baltic States and Poland to the Union will inside a few years change the economic and by that way also transport structure. After a short presentation of the geography and history the current European transport landscape will be described and current transport policies reviewed. Then some topics on the major changes during the last decennia as well as future studies will be presented. The paper draws heavily from the research projects ‐ SAMI, START and STEMM ‐ financed by the European Commission DGVII.
Abstract
North‐Eastern Europe is a peripheral area around the Baltic Sea. In some parts i.e. Scandinavia high living standards including developed transport systems exist when at [...]
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Analyses of PACTEL passive safety injection experiments with APROS, CATHARE and RELAP5 codes
J. Tuunanen, G. Kimber, J. Lillington, M. Frogheri, J. Vihavainen, E. Alien, F. D'Auria, G. Galassi, T. Williams

Collection of closed articles in transport research (2000). Vol. 2000, 6

Abstract
The European Commission fourth framework programme project ‘Assessment of passive safety injection systems of advanced light water reactors’ involved experiments on the PACTEL test facility and computer simulations of selected experiments. The experiments focused on the performance of passive safety injection systems (PSIS) of advanced light water reactors (ALWRs) in small break loss-of-coolant accident (SBLOCA) conditions. The PSIS consisted of a core make-up tank (CMT) and two pipelines. A pressure balancing line (PBL) connected the CMT to one cold leg. The injection line (IL) connected it to the downcomer. The project involved 15 experiments in three series. The experiments provided information about condensation and heat transfer processes in the CMT, thermal stratification of water in the CMT, and natural circulation flow through the PSIS lines. The project included validation of three thermal-hydraulic computer codes (APROS, CATHARE and RELAP5). The analyses showed the codes are capable of simulating the overall behaviour of the transients. The codes predicted accurately the core heatup, which occurred when the primary coolant inventory was reduced so much that the core top became free of water. The detailed analyses of the calculation results showed that some models in the codes still need improvements. Especially, further development of models for thermal stratification, condensation and natural circulation flow with small driving forces would be necessary for accurate simulation of the phenomena in the PSIS.
Abstract
The European Commission fourth framework programme project ‘Assessment of passive safety injection systems of advanced light water reactors’ involved experiments on the [...]
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VEHIL: a full-scale test methodology for intelligent transport systems, vehicles and subsystems
L. Verhoeff, D. Verburg, H. Lupker, L. Kusters

Collection of closed articles in transport research (2000). Vol. 2000, 5

Abstract
To enhance the efficiency and safety of today's road transport, the application of driver support systems and fully automated, intelligent transport systems becomes increasingly important. The safety and reliability requirements of these systems and their complexity are high, which results in a costly, time consuming development and testing process. This paper presents an intelligent vehicle hardware in the loop simulator for faster and more efficient development and testing of full-scale intelligent vehicle and transport systems. Its technical feasibility and added value are illustrated by applying the concept to a passenger car platooning experiment.
Abstract
To enhance the efficiency and safety of today's road transport, the application of driver support systems and fully automated, intelligent transport systems becomes increasingly [...]
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Backcasting as a tool to develop a sustainable transport scenario assuming emission reductions of 80-90%
B. Wee, K. Geurs

Collection of closed articles in transport research (2000). Vol. 2000, 4

Abstract
This article will summarise the results of The Netherlands pilot study commissioned by the Dutch Ministry of Housing, Spatial Planning and the Environment, and carried out by the Dutch National Institute of Public Health and the Environment (RIVM). This pilot study differed from existing sustainable transport scenario studies for four reasons: (i) very sharp emission reductions are assumed, (ii) not only 'forecasting' but also 'backcasting' scenarios are constructed, (iii) instrument packages and implementation time paths are described which - if carried out - would result in the necessary technological and behavioural changes to realize environmentally sustainable transport, and (iv) the social and economic impact of sustainable transport is assessed.
Abstract
This article will summarise the results of The Netherlands pilot study commissioned by the Dutch Ministry of Housing, Spatial Planning and the Environment, and carried out [...]
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Road - scaled Magic Formula for braking performance of cars
R. Hogt, J. Oosten

Collection of closed articles in transport research (2000). Vol. 2000, 3

Abstract
Ths skid resistance of the road surface is one of the parameters that influence the active vehicle safety and consequently the traffic safety. Up till now, in the Netherlands skid resistance has been evaluated by means of of a statistical relation between the skid resistance value and accident risk. In order to be able to fulfil the demands of a more detailed evaluation an approach is suggested with the focus on the physical description of mechanisms in traffic safety. This approach is innovative and quite different from standard solutions in traffic safety research. One of the major challenges in this approach is to integrate a wide range of disciplines, i.e. road technology, tyre-road interaction, vehicle dynamics and human factors for the prediction of the braking performance of vehicle from specified road characteristics. In this way, the braking performance model supports a better mutual understanding between the governments, road constructors and vehicle manufacturers. One of the crucial elements in the model is the accurate description of the tyre-road interaction. The Magic Formula tyre model is a general accepted model to describe interaction forces within the automotive industry. This paper focuses on the extension of the Magic Formula tyre model with speed dependent friction for especially the wet conditions and also the scaling of the Magic Formula parameters based on standard road-skid resistance and road macro texture measurements. This extended model is valid for dry and wet surfaces. It enables the scientist to enlarge the accuracy and validity range of the tyre-road interaction model towards a wide range of surfaces and thus increasing the accuracy of the prediction of the vehicle braking performance
Abstract
Ths skid resistance of the road surface is one of the parameters that influence the active vehicle safety and consequently the traffic safety. Up till now, in the Netherlands [...]
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The human element in car following models
W. Winsum

Collection of closed articles in transport research (1999). Vol. 1999, 2

Abstract
This commentary distinguishes between the engineering-inspired formalisms used by Brackstone, M., and McDonald, M. (Transportation Research Part F (1999)) and the psychological knowledge of, and assumptions about human behaviour when car following. It outlines a preliminarry mathematical model, based on psychological knowledge about car following behaviour by human drivers, which could be applied in traffic engineering, as a means of bringing these two ways of studying car following closer together.
Abstract
This commentary distinguishes between the engineering-inspired formalisms used by Brackstone, M., and McDonald, M. (Transportation Research Part F (1999)) and the psychological [...]
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Energy scenarios for European passenger transport in the year 2030
P. Nijkamp, S. Rienstra, R. Smokers

Collection of closed articles in transport research (2000). Vol. 2000, 2

Abstract
In this paper four energy scenarios for Westy-European passenger transport are developed. To start with, the present transport system as a base-line case is described and analysed. Next, for each scenario we sketch how the passenger transport system may look like in terms of the use of various existing and future transport technologies and the corresponding model split. Based on this information, expected energy consumption features of the various transport modes are described, data on the present fuel supply and electricity generation system are offered, and estimations of the future energy system are given. Then, the energy consumption and CO2 emissions associated with the future passenger transport systems are stressed and these impacts are compared with the current system. The conclusion is that a large-scale reduction of CO2 emissions is possible in several ways. Each way will cause many problems, since drastic policy measures will have to be introduced, which may affect economic growth and the lifestyles of individuals.
Abstract
In this paper four energy scenarios for Westy-European passenger transport are developed. To start with, the present transport system as a base-line case is described and [...]
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TOWARDS FINANCING AND PLANNING ROAD SAFETY AUDIT OPERATIONS IN NIGERIA
J. Odeleye

Collection of open articles in transport research (2000). Vol. 2000, 4

Abstract
Private-ownership of roads in Nigeria is still at the deliberation stage. In other words roads (tarred and untarred) are owned by Federal, State and Local authorities in Nigeria. Most of these roads, however, share a common characteristic of being “unsafe at any speed”, at any time of the day. This is as a result of the low quality of the road components, structures and patterns. For example, road surfaces are undulating and rough. Also, the poor standard of road infrastructure like guard railings/barriers; pavement marking and signs; illumination levels, traffic signals, horizontal/vertical alignment and sight lines contribute largely to the increasing carnage on Nigerian road network. This trend persists because authorities in Nigeria have practically relegated to the background regular road safety audit operations. This is an inevitable aspect of modern methods of road administration and management, which determines a number of traffic potentials concerning highway high collision locations; protection of errant vehicles from light poles, trees, ditches, replacement of damaged and missing signs, street lighting, capacity and level of service analysis. Finally, this paper suggests commissioning of a National Road Research Fund, with a view to developing an efficient road safety audit operational system. Also, the introduction of private initiatives and a Community-based Approach in road administration, as well as decentralization of road administration framework at all levels, will greatly help “engineer out” potentially unsafe features across Nigerian roads, towards a better road traffic environment in the 21st century. Document type: Article
Abstract
Private-ownership of roads in Nigeria is still at the deliberation stage. In other words roads (tarred and untarred) are owned by Federal, State and Local authorities in Nigeria. [...]
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FACTORS INFLUENCING THE OCCURRENCE AND OUTCOME OF CAR REAR-END COLLISIONS
B. Kampen

Collection of open articles in transport research (2000). Vol. 2000, 3

Abstract
Police based national accident data from the Netherlands show an enormous increase of both in number and in share of car rear-end collisions resulting in injury over the last 15 years. The average severity of those accidents remains low (illustrated by very low shares of occupants killed or hospitalised). However, the apparent increase in number of less severely injured as well as the personal and societal consequences of their injuries may well impose an increasing threat to the quality of life within the Dutch society. Based on national accident data as well as other relevant injury and traffic exposure data, the current situation in the Netherlands is described. Differences with respect to gender unexpectedly suggest that female drivers have a higher risk of their car being hit from behind than male drivers do. Less unexpectedly, differences are found between males and females with respect to injury susceptibility. These differences are analysed using controlling factors such as type of car, type of road, and exposure to traffic. It appears that not all of the indicators used point the same way; some of the increase mentioned may be due to registration biases. There is also a lack of adequate data with regard to the real number of whiplash injuries, their severity, and the longer-term consequences. Even if the total scope of the problem of whiplash injury in the Netherlands is still not fully known, the current estimate of societal consequences implicates a need for preventive measures. In the first place, accident prevention should be considered and a number of possible preventive measures (such as infrastructural improvement and application of ITS devices in cars to maintain distance in traffic) are discussed. Injury preventive measures (such as in car protection against whiplash) are already more generally available but still need much improvement. Document type: Article
Abstract
Police based national accident data from the Netherlands show an enormous increase of both in number and in share of car rear-end collisions resulting in injury over the last [...]
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TRAFFIC SAFETY AND ENVIRONMENT
A. Jansson, B. Horn

Collection of open articles in transport research (2000). Vol. 2000, 2

Abstract
Our transport system is not on a sustainable path. Achievements in terms of mobility have come at some considerable environmental, economic and social cost. Sustainability is a long-term concept, also demanding attention to its social dimension. For transport, this underscores a need to link considerations of the environment and traffic safety together. An integrated strategy implies systematic translation of a broad field of goals into a set of mutually reinforcing packages of measures. The focus is on improving the manner in which different actors recognise the need for co-operation and their readiness to implement it. The starting point is in improving communication. There are clear benefits in integration, in regard of both the synergy of actions as well as improved optimisation, but integration may also bring problems. This article is based on an international survey of an expert group formed by the OECD to review the issues and opportunities of integrating environmental and traffic safety strategies. The group assessed case studies from 12 countries and the European Union, using a classification scheme focusing on the decision contexts and life stages represented by the cases. The group's full report was published in 1997. In its conclusions, the group presents a pragmatic way ahead, and identifies some basic research needs. There are some important persisting questions: how to influence transport demand, how to increase the role of non-motorised traffic and public transport, how to find packages of measures relevant for entire regions surrounding large urban areas, and how to respond to the process of rapid motorisation in developing countries. There are as yet few measures dealing effectively with these issues, or taking them up with a concern for both safety and environment. While the approaches that have shown some success underline the importance of tailoring policies and strategies to the concrete situation of each country, they also demonstrate the importance of the international exchange of know-how. Document type: Article
Abstract
Our transport system is not on a sustainable path. Achievements in terms of mobility have come at some considerable environmental, economic and social cost. Sustainability [...]
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A Needs Assessment and Technology Evaluation for Roadside Identification of Commercial Vehicles
J. Walton, J. Crabtree

Collection of open conferences in research transport (1999). Vol. 1999, 16

Abstract
Throughout North America, selected public agencies have been assigned the responsibility for monitoring commercial vehicle traffic to make sure the commercial vehicles operating on public roadways are in safe operating condition, have proper registration and operating authority, are within legal size and weight limits, and have paid all appropriate fees and taxes. To accomplish this goal, all 50 States have established roadside monitoring and enforcement programs. With limited resources and increasingly heavy truck volumes, roadside enforcement officers must continually make decisions about which trucks to check and which to allow to proceed. This process of selecting some trucks for closer scrutiny, while allowing others to proceed unimpeded, is called “screening”. The Roadside Identification Feasibility Study was undertaken to identify methods of unique identification of commercial vehicles at the roadside for slow and high-speed electronic screening purposes. It was designed to be a comprehensive look at the technologies, focused on the needs of the Federal Highway Administration’s Office of Motor Carrier and Highway Safety (OMCHS) and the States.
Abstract
Throughout North America, selected public agencies have been assigned the responsibility for monitoring commercial vehicle traffic to make sure the commercial vehicles operating [...]
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The Transition Towards Free Flight: A Human Factors Evaluation of Mixed Equipage, Integrated Air-Ground, Free Flight ATM Scenarios
J. Hoekstra, R. Gent, R. Ruigrok

Collection of open conferences in research transport (1999). Vol. 1999, 15

Abstract
This paper describes the initial results of a simulation experiment in which the human factors implications of three Mixed Equipage, Integrated Air-Ground, Free Flight Air Traffic Management (ATM) scenarios were investigated. The experiment primarily addressed how to accommodate a fleet of mixed equipped aircraft, with and without Airborne Separation Assurance System (ASAS), in a transitional free flight era in which both air and ground players have defined responsibilities. All three transitional ATM operational concepts evaluated, were designed with the idea that equipping aircraft should be immediately beneficial to the airlines.
Abstract
This paper describes the initial results of a simulation experiment in which the human factors implications of three Mixed Equipage, Integrated Air-Ground, Free Flight Air [...]
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Dynamic Air Traffic Planning by Genetic Algorithms
S. Oussedik, D. Delahaye, M. Schoenauer

Collection of open conferences in research transport (1999). Vol. 1999, 13

Abstract
In the past, the first way to reduce the congestion of the Air Traffic Control System was to modify the structure of the airspace in order to increase the capacity (increasing the number of runways, increasing the number of sectors by reducing their size). This method has a limit due to the cost involved by new runways and the way to manage traffic in too small sectors (a controller needs a minimum amount of airspace to solve conflicts). The other way to reduce congestion is to modify the flight plans in order to adapt the demand to the available capacity. So, to reduce congestion, demand has to be spread in spatial and time dimension (route-slot allocation). Our research addresses the general time-route assignment problem using a static and a dynamic approach. A state of the art of the existing methods shows that this general bi-allocation problem is usually partially treated and the whole problem remains unsolved due to the induced complexity. GAs are then adapted to the problem. A sector congestion measure has been developed which gather the major control workload indicators. This measure is then computed for each proposed planning by referring to an off-line simulation. New problem-based stochastic operators have been developed and successfully applied on real instances of the problem.
Abstract
In the past, the first way to reduce the congestion of the Air Traffic Control System was to modify the structure of the airspace in order to increase the capacity (increasing [...]
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Very low power pipelines using significance compression
A. Gonzalez, J. Smith, R. Canal

Collection of open conferences in research transport (2000). Vol. 2000, 110

Abstract
Data, addresses, and instructions are compressed by maintaining only significant bytes with two or three extension bits appended to indicate the significant byte positions. This significance compression method is integrated into a 5-stage pipeline, with the extension bits flowing down the pipeline to enable pipeline operations only for the significant bytes. Consequently, register logic and cache activity (and dynamic power) are substantially reduced. An initial trace-driven study shows reduction in activity of approximately 30-40% for each pipeline stage. Several pipeline organizations are studied. A byte serial pipeline is the simplest implementation, but suffers a CPI (cycles per instruction) increase of 79% compared with a conventional 32-bit pipeline. Widening certain pipeline stages in order to balance processing bandwidth leads to an implementation with a CPI 24% higher than the baseline 32-bit design. Finally, full-width pipeline stages with operand gating achieve a CPI within 2-6% of the baseline 32-bit pipeline. Peer Reviewed
Abstract
Data, addresses, and instructions are compressed by maintaining only significant bytes with two or three extension bits appended to indicate the significant byte positions. [...]
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Human machine aspects of arrivals management in future air navigation environments
F. Vormer, M. Mulder, M. Van Paassen

Collection of open conferences in research transport (2000). Vol. 2000, 103
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L'acceptabilité des changements tarifaires dans le secteur des transports : comment concilier efficacité et équité ?
S. Souche, C. Raux

Collection of open conferences in research transport (2000). Vol. 2000, 89

Abstract
bility of pricing changes in the transport sector : how to reconcile efficiency and equity ? – This paper elaborates an analytical framework of the acceptability of pricing changes in the transport sector. This framework is built on the confrontation of the economic efficiency, territorial equity, horizontal equity, and vertical equity dimensions. This analytical framework is then applied to some ongoing urban and suburban road toll schemes in various countries. The analysis shows that these efficiency and equity dimensions combine themselves, by most often reinforcing the ones the others in their negative or positive aspects. This analysis also shows that these various dimensions of equity cannot be ignored on pain of failure. It enables us to identify the ways according to which the acceptability of urban road pricing could be improved. Un cadre d'analyse de l'acceptabilité des changements tarifaires dans le secteur des transports est élaboré. Ce cadre analytique est bâti sur la confrontation des dimensions de l'efficacité économique, de l'équité territoriale, de l'équité horizontale et de l'équité verticale. Ce cadre analytique est appliqué à quelques expériences de péages routiers urbains ou suburbains dans divers pays. Leur analyse montre que les dimensions de l'efficacité et de l'équité se conjuguent, en se renforçant le plus souvent les unes les autres dans leurs aspects négatifs ou positifs. Cette analyse montre aussi que ces différentes dimensions de l'équité ne peuvent être ignorées sous peine d'échec. Elle permet ainsi d'identifier les voies selon lesquelles l'acceptabilité de la tarification de la circulation urbaine pourrait être améliorée.
Abstract
bility of pricing changes in the transport sector : how to reconcile efficiency and equity ? – This paper elaborates an analytical framework of the acceptability of pricing [...]
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Designing interactive applications for air traffic control with the support of MEFISTO
B. R., F. C., G. H., G. P., M. P., P. P., P. F., R. C., S. C., S. P., T. S., W. P.

Collection of open conferences in research transport (2000). Vol. 2000, 88

Abstract
This short paper presents an overview of the approach developed within the MEFISTO project. An important element in the approach is the use of formal models and their integration with other, less formal, techniques. MEFISTO (Modelling, Evaluating and Formalising Interactive Systems using Tasks and interaction Objects) is a European Commission IVth Framework Reactive Long Term Research Esprit project. Its main goal is to investigate how the use of formal techniques can be introduced into the design of interactive safety-critical systems, such as Air Traffic Control applications (ATC). Also important is the evaluation of the design notations, computer support tools and the developed ATC prototypes. This type of application engenders an integrated satisfaction of both usability and safety requirements, as in some circumstances a human error can threaten human life. This means that the design of the interactive ATC environments provided to controllers requires the use of rigorous techniques and systematic methods that allow designers to identify possible problematic situations in advance and help in providing support to the end users. In addition, the use of formal techniques can provide precise documentation and can support representations of design rationale. To make the use of formal models more affordable, in MEFISTO we have paid particular attention to the use of software tools in order to ease their development and analysis, so yielding useful information for the designers in various phases of the design process. However, we are aware that formal techniques cannot cover all the needs in the design cycle. Thus, it is important to understand what other informal techniques should be used and how their integration with formal approaches should be carried out.
Abstract
This short paper presents an overview of the approach developed within the MEFISTO project. An important element in the approach is the use of formal models and their integration [...]
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Distributed reinforcement learning for a traffic engineering application
M. Pendrith

Collection of open conferences in research transport (2000). Vol. 2000, 86

Abstract
In this paper, the authors describe how a distributed reinforcement learning problem, in which the returns of many agents are simultaneously updating a single shared policy, is addressed by applying novel reinforcement learning techniques. A traffic simulator is used in the learning process. Two new algorithms are introduced: a value function-based algorithm and one that uses a direct policy evaluation approach. Both algorithms are shown to perform comparably well.
Abstract
In this paper, the authors describe how a distributed reinforcement learning problem, in which the returns of many agents are simultaneously updating a single shared policy, [...]
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$7.0/Mflops astrophysical N-body simulation with treecode on GRAPE-5
J. Makino, A. Kawai, T. Fukushige

Collection of open conferences in research transport (1999). Vol. 1999, 11

Abstract
an entry for the 1999 Gordon Bell price/performance prize, we report an astrophysical N-body simulation performed with a treecode on GRAPE-5 (Gravity Pipe 5) system, a special-purpose computer for astrophysical N-body simulations. The GRAPE-5 system has 32 pipeline processors specialized for the gravitational force calculation. Other operations, such as tree construction, tree traverse and time integration, are performed on a general purpose workstation. The total cost for the GRAPE-5 system is 40,900 dollars. We performed a cosmological N-body simulation with 2.1 million particles, which sustained a performance of 5.92 Gflops averaged over 8.37 hours. The price per performance obtained is 7.0 dollars per Mflops. Comment: 7 pages, 4 figures, 1999 Gordon Bell Prize Winner (price/performance category) Performance figures are improved. Two photographs are added
Abstract
an entry for the 1999 Gordon Bell price/performance prize, we report an astrophysical N-body simulation performed with a treecode on GRAPE-5 (Gravity Pipe 5) system, a special-purpose [...]
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The Direct Adjustment Algorithm: A TCP-Friendly Adaptation Scheme
H. Schulzrinne, D. Sisalem

Collection of open conferences in research transport (2000). Vol. 2000, 76

Abstract
Many distributed multimedia applications have the ability to adapt to fluctuations in the network conditions. By adjusting temporal and spatial quality to available bandwidth, or manipulating the playout time of continuous media in response to variations in delay, multimedia flows can keepa n acceptable QoS level at the end systems. In this study, we present a scheme for adapting the transmission rate of multimedia applications to the congestion level of the network. The scheme called the direct adjustment algorithm (DAA), is based on the TCP congestion control mechanisms and relies on the end-to-end Real Time transport Protocol (RTP) for feedback information. Our investigations of the DAA scheme suggest that simply relying on the the TCP-throughput model might result under certain circumstances in large oscillations and low throughput. However, DAA achieves, in general, high network utilization network and low losses. Also, the scheme is shown to be fair towards competing TCP traffic. However, with no support from the network, long distance connections receive less than their fair share.
Abstract
Many distributed multimedia applications have the ability to adapt to fluctuations in the network conditions. By adjusting temporal and spatial quality to available bandwidth, [...]
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"title"Crack growth monitoring in harsh environments by electrical potential measurements"/title"
D. Weinberg, W. Lloyd, W. Reuter

Collection of open conferences in research transport (1999). Vol. 1999, 10

Abstract
Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique is applicable to many severe environments because the sensitive equipment (electronics, operators) can be situated in a remote location, with only current and voltage probe electrical leads entering into the harsh environment. Experimental results showing the utility of the methodology are presented, and unique application concepts that have been examined by multiple experiments are discussed.
Abstract
Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. [...]
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Virtual Reality in Air Traffic Control
G. Johansson, R. Olsson, R. Davies, A. Trollås, R. Akselsson, M. Cepciansky, C. Källqvist, V. Bednarek, J. Eriksson

Collection of open conferences in research transport (2000). Vol. 2000, 71

Abstract
traffic control is a highly spatial work. However, there are currently no three-dimensional tools used in the education of air traffic controllers or in the operational work of air traffic control. This paper presents results from some pilot studies aiming to:"br /" -Find new techniques for visualization and editing of trajectories in air traffic control."br /" -Investigate how Virtual Reality (VR) can contribute to the air traffic controllers’ understanding of the air space and of certain situations. Two VR models have been developed. In one model a procedure called ‘holding’ is visualized. In the other VR model the different sectors in the air space are shown to make it easier for the air traffic controller to build a mental picture of a sector. In a training package the user can fly around in the sector and see how traffic passes through."br /" These introductory studies indicate the usefulness of new ways to present the third dimension in a variety of air traffic situations. The tools can be used to visualize a three dimensional situation and help the air traffic controller to build a mental model The most obvious application area is in training and education of air traffic controllers but other applications such as an explanation and communication tool in the investigation after an incident are of interest.
Abstract
traffic control is a highly spatial work. However, there are currently no three-dimensional tools used in the education of air traffic controllers or in the operational work [...]
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On the Evaluation of Dynamic Stresses in Pipelines Using Limited Vibration Measurements and FEA in the Frequency Domain
W. Moussa, A. AbdelHamid

Collection of open conferences in research transport (1999). Vol. 1999, 9

Abstract
practical technique is investigated for the determination of dynamic stresses in pipelines through the use of Finite Element Method (FEM) and field measurement vibrations at selected points. Numerical simulation of a harmonically loaded pipeline structure is used to establish the validity of the technique in the frequency domain. The analysis is carried out for a fixed-hinged pipe model. The results show that lack of coincidence between the vibration measurement points (VMPs) and the exciting force, or the use of only translational vibration measurements (TVMs) produce an approximate stress picture. The extent of the “error” in these cases is found to depend on the density of the VMPs and the proximity between these points and the exciting force location. A safety-related risk assessment is applied to find the minimum distance between measuring points that is needed to meet design codes reliability specifications.Copyright © 1998 by ASME
Abstract
practical technique is investigated for the determination of dynamic stresses in pipelines through the use of Finite Element Method (FEM) and field measurement vibrations [...]
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Airborne separation assurance and traffic management - Research of concepts and technology
G. Mark, J. David, R. Sheila, F. Monica

Collection of open conferences in research transport (1999). Vol. 1999, 8

Abstract
To support the need for increased flexibility and capacity in the future National Airspace System, NASA is pursuing an approach that distributes air traffic separation and management tasks to both airborne and ground-based systems. Details of the distributed operations and the benefits and technical challenges of such a system are discussed. Technology requirements and research issues are outlined, and NASA''s approach for establishing concept feasibility, which included development of the airborne automation necessary to support the concept, is discribed.
Abstract
To support the need for increased flexibility and capacity in the future National Airspace System, NASA is pursuing an approach that distributes air traffic separation and [...]
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An Assessment of the Capacity and Congestion levels at European Airports
A. Reynolds-Feighan, K. Button

Collection of open conferences in research transport (1999). Vol. 1999, 7

Abstract
This paper examines the current capacity of the EU's airport infrastructure and the main factors determining that capacity. The nature and role of airport services are detailed. The determination of capacity is examined with discussion of the influence which air traffic control factors, demand characteristics, environmental conditions and engineering design will have on capacity. The methods used to assess delay are detailed along with extensive data sketching the current state of Europe's system of large airports and the extent of infrastructure congestion. The options available to policy makers to improve the management and organisation of capacity are set out and critically discussed.
Abstract
This paper examines the current capacity of the EU's airport infrastructure and the main factors determining that capacity. The nature and role of airport services are detailed. [...]
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Using information in task models to support design of interactive safety-critical applications
C. Santoro, V. Sabbatino, F. Paternò

Collection of open conferences in research transport (2000). Vol. 2000, 41

Abstract
The use of models has entered into current practice when developing various types of software product. However, there is a lack of methods able to use the information contained in relevant models concerning human-computer interaction for supporting the design and development of user interfaces. In this paper, we propose a method for using information contained in formally represented task models in order to support the design of interactive applications, with particular attention to those applications where both usability and safety are the main concern. Examples taken from our experience in a case study from the domain of Air Traffic Control are introduced and further discussed to explain how the method can be applied.
Abstract
The use of models has entered into current practice when developing various types of software product. However, there is a lack of methods able to use the information contained [...]
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The derivation and analysis of the passenger peak hour: an empirical application to Brazil
P. Wang, D. Pitfield

Collection of open conferences in research transport (1999). Vol. 1999, 6

Abstract
Many different definitions are currently used to define a design `peakâ€™ hour at airports, such that the majority of passengers receive adequate service levels and only an acceptably small proportion experience the impact of congestion. The evaluation of level of service provision depends on this definition. Previous definitions have either used a nominal hour below the absolute peak or have taken a representative hour from the schedule of flights. This paper endeavours to define this level of traffic empirically. Data for 48 Brazilian airports covering a five-year period are analysed to develop a methodology for and determine the appropriate peak hour for design standards. This empirically derived traffic level is regressed against annual traffic levels to establish a relationship that should enable the forecast of design peak hour demand with changing annual throughputs.
Abstract
Many different definitions are currently used to define a design `peakâ€™ hour at airports, such that the majority of passengers receive adequate service levels and only [...]
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Retrofit systems for reconfiguration in civil aviation
J. Wohletz

Collection of open conferences in research transport (1999). Vol. 1999, 5

Abstract
This paper outlines a new concept for retrofitting a reconfiguration module to an existing control law. The concept is motivated by the need for low cost, add-on modules that improve air safety in the existing fleet of civil air transport vehicles. A direct adaptive approach that accommodates control surface nonlinearities is adopted, which uses a slowly adapting model of the closed-loop aircraft as the reference model. The motivation,benefits, and components of the architecture are detailed. In addition, the issues of control surface magnitude and rate saturation are addressed. A proof of stability is outlined for input-error adaptation when position and rate saturation are present. using an F/A-18 nonlinear simulator. The primary adaptive component is demonstrated
Abstract
This paper outlines a new concept for retrofitting a reconfiguration module to an existing control law. The concept is motivated by the need for low cost, add-on modules that [...]
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Evaluating the Effective Friction Factor and Overall Heat Transfer Coefficient During Unsteady Pipeline Operation
S. Rizopoulos, G. Price, H. Golshan, R. McBrien

Collection of open conferences in research transport (1999). Vol. 1999, 3

Abstract
This paper presents a method to determine the effective friction factor and overall heat transfer coefficient for a high pressure, natural gas pipeline during fully transient flow conditions. Time varying SCADA (Supervisory Control And Data Acquisition) measurements at the pipeline boundaries (i.e., inlet and outlet) provide boundary conditions for a transient flow model as well as additional information that is utilized to determine these parameters. The resulting friction factor and overall heat transfer coefficient minimize the least-squared difference between the additional SCADA measurements at the pipeline outlet and the corresponding values predicted from the transient flow model. This concept is referred to as parameter estimation. The transient flow model is based on a numerical solution of the one-dimensional, unsteady flow equations (i.e., continuity, momentum and energy) which are discretized using a highly accurate compact finite-difference scheme."/jats:p" "jats:p"The transient flow model and parameter estimation are incorporated into a computer program that is initially tested on a simple pipeline with steady flow conditions. Here, the predicted outlet pressure and temperature, using the estimated friction factor and overall heat transfer coefficient, exactly matches the corresponding prescribed values. Subsequently, a portion of the Foothills Pipe Line Ltd. transmission system in Alberta is considered using time varying SCADA flow measurements. The resulting outlet pressure and temperature from the transient flow model are in good agreement with SCADA measurements at this location.
Abstract
This paper presents a method to determine the effective friction factor and overall heat transfer coefficient for a high pressure, natural gas pipeline during fully transient [...]
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Nonlinear dynamics in the modeling of helicopter rotor blade lead/lag motion
R. King

Collection of open thesis in transport research (1999). Vol. 1999, 6

Abstract
Until recently, computer simulations of helicopter rotor dynamics have employed equations of motion that have been linearized or simplified. These modified equations of motion did not allow for the evaluation of nonlinear material properties in the rotor since higher order terms in the dynamics had been modified in the simplification process. With recent advances in both computer simulation hardware and symbolic mathematic manipulation software, the full nonlinear equations of motion may be utilized in helicopter rotor simulations. This dissertation reports on the use of the full nonlinear equations of motion in the analysis of rotor blade lead/lag motion and its effect on rotor hub and rigid body fulselage motion. Nonlinear modeling methods are implemented using Maple symbolic mathematic manipulation software and Matlab and Simulink computer simulation environments. Results are compared to the RAH- 66 Comanche Froude scale wind tunnel article and new methodologies evaluated in the search for a damperless rotor system that is free of ground and air resonance mechanical instabilities http://www.archive.org/details/nonlineardynamic00king Naval Postgraduate School author. Approved for public release; distribution is unlimited.
Abstract
Until recently, computer simulations of helicopter rotor dynamics have employed equations of motion that have been linearized or simplified. These modified equations of motion [...]
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POINT OF ACCESS: A user's perspective on mass transit entrance system design
E. Shirey

Collection of open thesis in transport research (1999). Vol. 1999, 5

Abstract
The less glamorous aspects of a transportation system's infrastructure, such as signage, ticketing systems, and wayfinding elements, typically get little or no attention from creative professionals. Instead they are purchased directly from manufacturers as minimally customized off-the-shelf components. Paradoxically, these parts that go unconsidered and undesigned are what transit riders most directly interact with, and what most affects their experience of the transit system/product. This thesis focuses specifically on the Washington DC Metro Area Transportation Authority's (WMATA) Metrorail, aiming to reshape the entrance segment of this public transportation experience by increasing both appeal and accessibility. The design process began with primary and secondary design research, using observational and interactive methods to produce an informed picture of Metrorail users' current perspectives. A design strategy was then developed from the collective research findings, which led to a period of blue-sky ideation and finally the design of elegant and accessible mass transit entrance system components. Master of Science
Abstract
The less glamorous aspects of a transportation system's infrastructure, such as signage, ticketing systems, and wayfinding elements, typically get little or no attention [...]
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AHS Maglev System Architecture
S. Siridhara

Collection of open thesis in transport research (1999). Vol. 1999, 4

Abstract
In the period between 1993-1998 a vision was presented of an Automated Highway System developed under a contract naming Virginia Tech one of the three ITS Research Centers of Excellence in the United States by the Federal Highway Administration. The AHS envisioned would consist of a guideway constructed in the rights-of-way of the Interstate Highway System which would utilized magnetic levitation ("maglev") to propel closely-space, individual vehicles at high speeds with full longitudinal and lateral control. In this dissertation the system architecture is described in detail. The system architecture is organized according to system structural, system operational, and vehicle subsystem technological elements. The structural aspects are concerned with the decision making capability allocated between a vehicle and the guideway, the characteristics of the control and sensing equipment contained within the guideway, the traveling unit configuration, and certain of the vehicle's structural and equipment considerations. The operational aspects are concerned with vehicle entrainment policy, system fleet mixture, network type and control functions, and guideway lane separation requirements. The vehicle subsystem and the vehicle longitudinal and lateral control subsystem. The operational architecture concentrates on developing and evaluating strategies for forming platoons of vehicles on the guideway since the average platoon sizes determine the practical capacity of the guideway as well as the safety of operation. It is instructive to review how platoons form naturally on conventional highways as a prelude to developing a strategy for forming platoon on the AHS Maglev Guideway. A novel, non-linear car-following model called "car maneuvering" is explored by defining the stimuli on the right-hand side of the model in terms of several vehicles ahead of the response vehicle. In order to add still more realism in developing a strategy for platoon formation in a guideway under automatic control, an additional spacing dependent term is introduced to achieve a "magnetic coupling headway" between platooned vehicles. Once vehicles are magnetically coupled, the desired intraplatoon headway is maintained through attraction and repulsion. In this dissertation the term "architecture" is interpreted in the broadest possible sense based on the assumption that any transportation system intended to serve society throughout the 21st Century and beyond must address a hierarchy of goals and issues ranging from the strategic (sustainable development) to the tactical (the concept of operations) and including the in-between (interfacing with the existing transportation system). In the past, transportation planning, policy, investment and operating decisions have been made in isolation from each other with incomplete information inputs from a broad base of disciplines and sectors, without a synthesizing instrumentality. A new approach is described to promote the best informed decisions governing planning and management. The approach features a realistic framework for allocating public sector-private sector effort, an instrumentality for generating the knowledge needed to conceive and implement the new transportation paradigm, and a strategic vision for rallying support. The new approach to the problem begins with a strategic vision for society's AHS infrastructure. We believe that the strategic vision must be based on the concept of "sustainable development." To affect this new strategic vision, higher budgets will be a necessary, but not a sufficient condition. A fundamental Decision Support System (DSS) with knowledge bases with contributions from the braid spectrum of science and engineering disciplines, and a methodology based on system dynamics capable of synthesizing these contributions is proposed. The AHS Maglev Alternative is compared to a "Do-Nothing" Alternative and a "Traditional Expansion" Alternative using user and nonuser benefit analyses. The advantages of AHS Maglev are seen to be overwhelming. Moreover, the ability of AHS Maglev to alleviate airport congestion by reducing short and medium range of flights, and to serve as a structuring device for rational population distribution is shown. Ph. D.
Abstract
In the period between 1993-1998 a vision was presented of an Automated Highway System developed under a contract naming Virginia Tech one of the three ITS Research Centers [...]
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Not available
A. Figueiredo

Collection of open thesis in transport research (1999). Vol. 1999, 3

Abstract
O trabalho apresenta uma metodologia para o planejamento empresarial do serviço de transporte urbano por ônibus. A metodologia foi concebida a partir de três pontos: a fundamentação metodológica, a revisão bibliográfica e a aplicação de uma técnica de análise de múltiplos critérios de apoio à tomada de decisão. A fundamentação metodológica do trabalho está no entendimento de que as variáveis relacionadas com a cultura, com a sociedade e com o poder político e econômico têm uma forte influência no processo de planejamento. Portanto, precisam ser consideradas na definição do produto completo da empresa, na gama de serviços a ser ofertado, na configuração da empresa e de suporte externo da oferta dos serviços e de insumos de produção. O desempenho empresarial é avaliado pela forma de gestão implementada na organização. A revisão bibliográfica permitiu selecionar e sistematizar os critérios de apoio à tomada de decisão e as alternativas para estruturar o planejamento, contemplando a organização interna, a avaliação e regulamentação do mercado de serviço do transporte urbano por ônibus. O método de múltiplos critérios de apoio à tomada de decisão adotado foi o Analytic Hierarchy Process - AHP. Sua aplicação prioriza, em escala de importância, os critérios adotados de apoio à tomada de decisão e as alternativas de atuação contendo ações a serem implementadas para consolidar o planejamento empresarial. A metodologia permite ao empresário de transporte urbano por ônibus adotar um procedimento sistemático para consolidar o planejamento empresarial como um processo contínuo de gestão e de avaliação de resultados, ponderando inclusive as restrições de atuar em um mercado regulamentado. The work presents a methodology for the managment planning of the urban bus passenger transportation service. The methodology was conceived three starting points: the methodological basis, a bibliographical review and the implementation of an analysis technique of different support criteria for decision making. The methodological basis of the work assumes that the variables related to the culture, society and to the political and economical power have a strong influence upon the planning process. Therefore, they must be taken into account when defining the total product of the enterprise, the range of services offered, the format of the enterprise and the external support of production services and assets available. The enterprise performance is evaluated by the type of management implemented in the organization. The bibliographical review allowed the selection and systematization of supporting criteria in decision making as well as the alternatives to structure the planning, taking into consideration the internal organization, the evaluation and regulation of the market in relation to urban bus transportation services. The different criteria of support to decision making adopted was the Analytic Hierarchy Process - AHP. Its application, by priority, is in order of importance, the criteria adopted and the alternatives of performance containing actions to be implemented in order to consolidate the planning process. The methodology allows the entrepreneur to use the enterprise planning as a continuous process of performance and of evaluation of results, including considerations on restrictions of performance in a regulated market.
Abstract
O trabalho apresenta uma metodologia para o planejamento empresarial do serviço de transporte urbano por ônibus. A metodologia foi concebida a partir de três pontos: a [...]
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Computational analysis of the off-design performance of a Mach 6 (L/D) ispmax optimized waverider
E. Coyne

Collection of open thesis in transport research (1999). Vol. 1999, 2

Abstract
In a continuation of ongoing Naval Postgraduate School efforts to study the performance characteristics of waverider configured vehicles, a computational fluid dynamic (CFD) analysis of the Mach 6 L/DI(sp)(max) optimized Price waverider was conducted. This analysis was performed to determine the theoretical force and moment data over a broad Mach number spectrum, and to compare theoretical and experimental results in the subsonic flight regime. The CFD determination of force and moment data represents a continuation of the ongoing analysis of the Price waverider configuration. Selected viscous and inviscid flow solutions for flight conditions in the range 0.3 " M(infinity) "6. 0, as well as a subsonic (M(infinity) = 03) angle of attack sweep, were conducted using NASA CFD software (OVERFLOW1.8b). Examination of the computed converged flow field solutions suggests that the surface pressure distributions and Mach number contours surrounding the holy are valid. Low speed force and moment coefficient data are shown to exhibit reasonable agreement with the available subsonic wind tunnel data. Additionally, supersonic CFD results show the development of the expected shock layer, exhibiting an attached shock bed at the design Mach number (M(infinity) = 6.0). Evaluation of the computed Mach number effects on lift and drag coefficients at subsonic, transonic and supersonic Mach numbers suggests that the Price waverider may exhibit some flight instabilities across the flight Mach number spectrum. http://www.archive.org/details/computationalana00coyn Lieutenant Commander, United States Navy Approved for public release; distribution is unlimited.
Abstract
In a continuation of ongoing Naval Postgraduate School efforts to study the performance characteristics of waverider configured vehicles, a computational fluid dynamic (CFD) [...]
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Infrastructure Development and Regulatory Reform in Sub-Saharan Africa
A. Goldstein

Collection of open reports in transport research (1999). Vol. 1999, 29

Abstract
This Technical Paper analyses the main policy issues raised by regulatory reform in air transport in sub–Saharan Africa. Its basic premise is that improving air infrastructure is of paramount importance for the region as it tries to integrate more thoroughly into the world economy. On the basis of the experience of OECD countries with privatisation, liberalisation, and regulatory design, the author analyses progress being made in sub– Saharan Africa and identifies three important case studies: the restructuring of the regional airline of Francophone Western Africa, the sell–off of the state–owned airline of Kenya, and the overall reform process in South Africa, by far the largest market in the sub–continent.The analysis highlights the importance of regional dynamics in the upgrading of the air transport industry in developing and emerging areas. Sub–Saharan Africa has made smaller progress in this respect than, for instance, Central America. As the start of the Millenium Round and ...
Abstract
This Technical Paper analyses the main policy issues raised by regulatory reform in air transport in sub–Saharan Africa. Its basic premise is that improving air infrastructure [...]
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SN-268 encasement leak detection ANA-WT-LDSTA-335 acceptance test procedure
D. Vandyke

Collection of open reports in transport research (1999). Vol. 1999, 28

Abstract
This document describes the method used to test design criteria for encasement leak detector system installed in 241-AN-A Encasement Line SN-268, located at 200E Tank Farms. This procedure provides instructions for demonstrating that the pit leak detection relay cabinet and intrinsically safe probe circuit is fully operable.
Abstract
This document describes the method used to test design criteria for encasement leak detector system installed in 241-AN-A Encasement Line SN-268, located at 200E Tank Farms. [...]
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Walkdown and Evaluation Report (ETN-98-0005) S-Farm Pit 241-S-B to Valve Pit 241-S-D
D. HICKS

Collection of open reports in transport research (1999). Vol. 1999, 27

Abstract
This document addresses the initial investigation of the as-found condition of the partially constructed 2414 Overground Transfer (OGT) system. It also addresses the evaluation of design deficiencies and their resolution, and includes before and after photographs, lists of drawings and Engineering Change Notices, and all design calculations.
Abstract
This document addresses the initial investigation of the as-found condition of the partially constructed 2414 Overground Transfer (OGT) system. It also addresses the evaluation [...]
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DOE handbook: Design considerations
S. Safety

Collection of open reports in transport research (1999). Vol. 1999, 26

Abstract
The Design Considerations Handbook includes information and suggestions for the design of systems typical to nuclear facilities, information specific to various types of special facilities, and information useful to various design disciplines. The handbook is presented in two parts. Part 1, which addresses design considerations, includes two sections. The first addresses the design of systems typically used in nuclear facilities to control radiation or radioactive materials. Specifically, this part addresses the design of confinement systems and radiation protection and effluent monitoring systems. The second section of Part 1 addresses the design of special facilities (i.e., specific types of nonreactor nuclear facilities). The specific design considerations provided in this section were developed from review of DOE 6430.1A and are supplemented with specific suggestions and considerations from designers with experience designing and operating such facilities. Part 2 of the Design Considerations Handbook describes good practices and design principles that should be considered in specific design disciplines, such as mechanical systems and electrical systems. These good practices are based on specific experiences in the design of nuclear facilities by design engineers with related experience. This part of the Design Considerations Handbook contains five sections, each of which applies to a particular engineering discipline.
Abstract
The Design Considerations Handbook includes information and suggestions for the design of systems typical to nuclear facilities, information specific to various types of special [...]
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Requirements Verification Report AN Farm to 200E Waste Transfer System for Project W-314 Tank Farm Restoration and Safe Operations
D. MCGREW

Collection of open reports in transport research (1999). Vol. 1999, 25

Abstract
This Requirements Verification Report (RVR) for Project W-314 ''AN Farm to 200E Waste Transfer System'' package provides documented verification of design compliance to all the applicable Project Development Specification (PDS) requirements. Additional PDS requirements verification will be performed during the project's procurement, construction, and testing phases, and the RVR will be updated to reflect this information as appropriate.
Abstract
This Requirements Verification Report (RVR) for Project W-314 ''AN Farm to 200E Waste Transfer System'' package provides documented verification of design compliance to all [...]
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Multi-Criteria Trucking Freeway Performance Measures for Congested Corridors
N. Wheeler

Collection of open reports in transport research (2000). Vol. 2000, 24

Abstract
This research focuses on the development of multi-criteria tools for measuring and analyzing the impacts of recurring and non-recurring congestion on freight. Unlike previous studies, this work employs several distinct data sources to analyze the impacts of congestion on interstate 5 (I-5) in the Portland Metropolitan Area: global positioning system (GPS) data from commercial trucks, Oregon DOT corridor travel time loop data and incident data. A new methodology and algorithms are developed to combine these data sources and to estimate the impacts of recurrent and non-recurrent congestion on freight movements’ reliability and delays, costs, and emissions. The results suggest that traditional traffic sensor data tend to underestimate the impacts of congestion on commercial vehicles travel times and variability. This research shows that congestion is not only detrimental for carriers and shippers costs but also for the planet due to increases in greenhouse gas emissions, and for the local community due to increases in oxides of nitrogen, particulate matter, and other harmful pollutants. The methodology developed throughout this work has the potential to provide useful freight operation and performance data for the freight community, transportation decision makers, and other transportation stakeholders.
Abstract
This research focuses on the development of multi-criteria tools for measuring and analyzing the impacts of recurring and non-recurring congestion on freight. Unlike previous [...]
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A discussion on the methodology for calculating radiological and toxicological consequences for the spent nuclear fuel project at the Hanford Site
P. Rittmann

Collection of open reports in transport research (1999). Vol. 1999, 24

Abstract
This report contains technical information used to determine accident consequences for the Spent Nuclear Fuel Project safety documents. It does not determine accident consequences or describe specific accident scenarios, but instead provides generic information.
Abstract
This report contains technical information used to determine accident consequences for the Spent Nuclear Fuel Project safety documents. It does not determine accident consequences [...]
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LARGE-SCALE CO2 TRANSPORTATION AND DEEP OCEAN SEQUESTRATION
H. Sarv

Collection of open reports in transport research (1999). Vol. 1999, 23

Abstract
Technical and economical feasibility of large-scale CO{sub 2} transportation and ocean sequestration at depths of 3000 meters or grater was investigated. Two options were examined for transporting and disposing the captured CO{sub 2}. In one case, CO{sub 2} was pumped from a land-based collection center through long pipelines laid on the ocean floor. Another case considered oceanic tanker transport of liquid carbon dioxide to an offshore floating structure for vertical injection to the ocean floor. In the latter case, a novel concept based on subsurface towing of a 3000-meter pipe, and attaching it to the offshore structure was considered. Budgetary cost estimates indicate that for distances greater than 400 km, tanker transportation and offshore injection through a 3000-meter vertical pipe provides the best method for delivering liquid CO{sub 2} to deep ocean floor depressions. For shorter distances, CO{sub 2} delivery by parallel-laid, subsea pipelines is more cost-effective. Estimated costs for 500-km transport and storage at a depth of 3000 meters by subsea pipelines and tankers were 1.5 and 1.4 dollars per ton of stored CO{sub 2}, respectively. At these prices, economics of ocean disposal are highly favorable. Future work should focus on addressing technical issues that are critical to the deployment of a large-scale CO{sub 2} transportation and disposal system. Pipe corrosion, structural design of the transport pipe, and dispersion characteristics of sinking CO{sub 2} effluent plumes have been identified as areas that require further attention. Our planned activities in the next Phase include laboratory-scale corrosion testing, structural analysis of the pipeline, analytical and experimental simulations of CO{sub 2} discharge and dispersion, and the conceptual economic and engineering evaluation of large-scale implementation.
Abstract
Technical and economical feasibility of large-scale CO{sub 2} transportation and ocean sequestration at depths of 3000 meters or grater was investigated. Two options were [...]
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Analysis of Two Biomass Gasification/Fuel Cell Scenarios for Small-Scale Power Generation
W. Amos

Collection of open reports in transport research (1999). Vol. 1999, 22

Abstract
Two scenarios were examined for small-scale electricity production from biomass using a gasifier/fuel cell system. In one case, a stand-alone BCL/FERC gasifier is used to produce synthesis gas that is reformed and distributed through a pipeline network to individual phosphoric acid fuel cells. In the second design, the gasifier is integrated with a molten carbonate fuel cell stack and a steam bottoming cycle. In both cases, the gasifiers are fed the same amount of material, with the integrated system producing 4 MW of electricity, and the stand-alone design generating 2 MW of electricity.
Abstract
Two scenarios were examined for small-scale electricity production from biomass using a gasifier/fuel cell system. In one case, a stand-alone BCL/FERC gasifier is used to [...]
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State-level accident rates of surface freight transportation : a reexamination.
M. Tompkins, C. Saricks

Collection of open reports in transport research (1999). Vol. 1999, 21

Abstract
State-level accident rates for truck, rail, and barge transportation have been updated for mid-1990s shipping conditions. The updated accident, fatality, and injury rates reflect multiyear data for interstate-registered highway carriers, American Association of Railroads member carriers (i.e., all Class 1 and Class 2 railroads), and coastal and internal waterway barge traffic. Adjustments have been made to account for the share of highway combination-truck traffic actually attributable to interstate-registered carriers and for duplicated or otherwise inaccurate or unusable entries in the public-use accident data files applied. State-to-state variation in rates, reflecting recent developments in freight flows, the possible effect of speed limit changes on highway rates, and the stability of rates over time, are discussed. Carrier-specific information was used to confirm the general accuracy of the computed rates for highway shipments. Study conclusions suggest that these rates may be used for the next several years. However, further investigation is suggested, within two to three years, to verify or reject the emergence of a trend toward higher truck accident rates in states that raised highway speed limits between 1995 and 1996.
Abstract
State-level accident rates for truck, rail, and barge transportation have been updated for mid-1990s shipping conditions. The updated accident, fatality, and injury rates [...]
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On the Estimation of Volumes of Roadways: An Investigation of Stop-Controlled Minor Legs
J. Barnett

Collection of open reports in transport research (2000). Vol. 2000, 21

Abstract
This effort seeks to answer the question; can a transferable model be developed from easily obtainable, publicly available land-use, census, roadway, and network data for the use in safety performance functions? 474 stopcontrolled minor legs were used as the training data set using ordinary least squares regression. A best-fit model of maximum independent variables, n=12 was chosen using an exhaustive approach using Mallow's Cp to select the model with least bias in the predictors. The results of the analysis revealed that the combination of variables from Washington, Ohio, and North Carolina did not have a strong relationship. The best-fit model incorporated functional class information of the major-leg, minor leg functional class information, longitudinal markings, access to a parking lot, and population density of census tract. Validation of the model demonstrated an average 59 percent error between the model estimated and actual AADT values for validation data set (n=54). Furthermore, separate models for each state revealed a lack of uniformity in the dependent variables, and more variance description of the state specific AADT.
Abstract
This effort seeks to answer the question; can a transferable model be developed from easily obtainable, publicly available land-use, census, roadway, and network data for [...]
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The Influence of Shared Mobility and Transportation Policies on Vehicle Ownership: Analysis of Multifamily Residents in Portland, Oregon
E. Ruas

Collection of open reports in transport research (2000). Vol. 2000, 20
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A queueing based traffic flow model
N. Vandaele, A. Verbruggen, T. Woensel

Collection of open reports in transport research (2000). Vol. 2000, 19

Abstract
The assessment of uninterrupted traffic flow is traditionally based on empirical methods. We develop some analytic queueing models based on traffic counts and we model the behavior of traffic flows as a function of some of the most relevant determinants. These analytic models allow for parameterized experiments, which pave the way towards our research objectives: assessing what-if scenarios and sensitivity analysis for traffic management, congestion control, traffic design and the environmental impact of road traffic (e.g. emission models). The impact of some crucial modelling parameters is studied in detail and links with the broader research objectives are given. We illustrate our results for a highway, based on counted traffic flows in Flanders.
Abstract
The assessment of uninterrupted traffic flow is traditionally based on empirical methods. We develop some analytic queueing models based on traffic counts and we model the [...]
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Traffic Congestion Mitigation as an Emissions Reduction Strategy
A. Bigazzi

Collection of open reports in transport research (2000). Vol. 2000, 16
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Interface Control Document Between the Double Shell Tanks (DST) System and the Plutonium Finishing Plan (PFP)
T. May

Collection of open reports in transport research (1999). Vol. 1999, 19

Abstract
This document identifies the requirements and responsibilities for all parties to support waste transfer from the Plutonium Finishing Plant (PFP) facility to the Double-Shell Tank (DST) System of the River Protection Project (RPP). This Interface Control Document (ICD) will not attempt to control the physical portion of this interface because the physical equipment making up this interface, and any associated interface requirements, are already in place, operational and governed by existing operating specifications and other documentation. The PFP and DST Systems have a direct physical interface (the waste transfer pipeline) that travels between the 241-2 Building (TK-D5) and DST SY-102 via 244-TX double-contained receiver tank (DCRT). The purpose of the ICD process is to formalize working agreements between the RPP DST System and organization/companies internal and external to RPP. This ICD has been developed as part of the requirements basis for design of the DST System to support the Phase I Privatization effort.
Abstract
This document identifies the requirements and responsibilities for all parties to support waste transfer from the Plutonium Finishing Plant (PFP) facility to the Double-Shell [...]
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Analysis of Bracket Assembly for Diversion Box Leak Detector
H. Ziada

Collection of open reports in transport research (1999). Vol. 1999, 18

Abstract
This Supporting Document Presents Structural and Stress Analysis of a Bracket Assembly for the diversion box leak detectors related to the Cross Site Transfer Project. The results show that the assembly meets the requirements for dead load and natural phenomena hazards loads (seismic and wind).
Abstract
This Supporting Document Presents Structural and Stress Analysis of a Bracket Assembly for the diversion box leak detectors related to the Cross Site Transfer Project. The [...]
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Interface Control Document between the Double Shell Tanks (DST) System and T Plant
T. May

Collection of open reports in transport research (1999). Vol. 1999, 17

Abstract
This Interface Control Document (ICD) describes the interface between the Double-Shell Tank (DST) System and T Plant. T Plant generates waste during decontamination activities. These facilities do not have a direct physical interface since the waste will be moved by tank trailer to the 204-AR waste unloading facility. The purpose of the ICD process is to formalize working agreements between the River Protection Project (WP) DST System and organization/companies internal and external to RPP. This ICD has been developed as part of the requirements basis for design of the DST System to support the Phase I Privatization effort.
Abstract
This Interface Control Document (ICD) describes the interface between the Double-Shell Tank (DST) System and T Plant. T Plant generates waste during decontamination activities. [...]
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Interface Control Document Between the Tank Farm System and the Central Waste Complex (CWC) or the Low Level Burial Ground
T. May

Collection of open reports in transport research (1999). Vol. 1999, 16

Abstract
This Interface Control Document (ICD) describes the interface between the Tank Farm System and the Central Waste Complex (CWC) or the Low-Level Burial Ground (LLBG). The Tank Farm System generates solid waste during operations. These facilities do not have a direct physical interface since the waste will be moved by truck to the CWC or LLBG. The purpose of the ICD process is to formalize working agreements between the River Protection Project (RPP) Tank Farm System and organization/companies internal and external to RPP. This ICD has been developed as part of the requirements basis for design of the DST System to support the Phase I Privatization effort. The signatures on the cover page of this document indicate agreement between the parties that this document reflects the current technical baseline for each system and that the requirements contained in this document will not be revised without the agreement of all parties.
Abstract
This Interface Control Document (ICD) describes the interface between the Tank Farm System and the Central Waste Complex (CWC) or the Low-Level Burial Ground (LLBG). The Tank [...]
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The ‘labour question’ in nineteenth century Brazil: railways, export agriculture and labour scarcity
L. Lamounier

Collection of open chapters of books in transport research (2000). Vol. 2000, 24
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Traffic Management in ATM Networks: An Overview
C. Blondia, O. Casals

Collection of open chapters of books in transport research (2000). Vol. 2000, 22

Abstract
The main objectives of traffic management in ATM networks are to protect the user and the network in order to achieve network performance objectives and to use the available resources in an efficient way. In order to achieve these objectives the profile of the cell stream of each connection needs to be described adequately by means of a set of traffic parameters, together with an indication of the required level of QoS. The relationship between network performance and traffic characteristics and QoS is structured by means of ATM layer Service Categories and Transfer Capabilities. Each Category/Capability is provided with a number of traffic congestion and traffic control mechanisms needed to guarantee the required QoS of the category while achieving a high level of efficiency. This paper presents a state-of-the-art of traffic management in ATM networks. An overview is given of the Service Categories, together with the most important control and congestion schemes: CAC, UPC, traffic shaping, priority control, resource management, flow control, packet discarding schemes.
Abstract
The main objectives of traffic management in ATM networks are to protect the user and the network in order to achieve network performance objectives and to use the available [...]
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Sampling and analysis plan for the preoperational environmental survey of the project w 314 pipeline
R. MITCHELL

Collection of open reports in transport research (1999). Vol. 1999, 14

Abstract
This document provides a detailed description of the Sampling and Analysis Plan for the Preoperational Survey to be conducted for the W-314 Pipeline in the 200 East Area. Document type: Report
Abstract
This document provides a detailed description of the Sampling and Analysis Plan for the Preoperational Survey to be conducted for the W-314 Pipeline in the 200 East Area. Document [...]
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Mitigated subsurface transfer line leak resulting in a surface pool
D. SCOTT

Collection of open reports in transport research (1999). Vol. 1999, 13

Abstract
This analysis evaluates the mitigated consequences of a potential waste transfer spill from an underground pipeline. The spill forms a surface pool. One waste composite, a 67% liquid, 33% solid, from a single shell tank is evaluated. Even drain back from a very long pipeline (50,000 ft), does not pose dose consequences to the onsite or offsite individual above guideline values. Document type: Report
Abstract
This analysis evaluates the mitigated consequences of a potential waste transfer spill from an underground pipeline. The spill forms a surface pool. One waste composite, a [...]
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Construction integrity assessment report etn 98 0005 s farm overground transfer ogt system valve pit 241 s b to valve pit 241 s d
D. HICKS

Collection of open reports in transport research (1999). Vol. 1999, 12

Abstract
The S-Farm overground transfer (OGT) line will bypass the existing line(s), between valve pits 241-S-B and 241-S-D that no longer meet system requirements. The new OGT line will provide a waste transfer pipeline between these valve pits in support of saltwell pumping activities. The length of the OGT line is approximately 180 ft from pit to pit. The primary pipe is nominal 1-in. diameter stainless steel (SST) braided Ethylene-propylene Diene Monomer (EPDM) hose. The encasement pipe is a nominal 3-in., flanged, SST pipe made up of several different length pipe spool pieces (drawing H-2-829564, sh. 1 and sh. 2). The OGT line slopes from valve pit 241-S-B toward valve pit 241-S-D. At each end, the primary and encasement pipe connect to a pit entry spool piece. The pit entry spool pieces are constructed of prefabricated SST materials. These spool pieces allow for the separation of the primary and encasement pipelines after the pipes have entered the valve pits (drawing H-2-818280, sh. 2). The pit entry spool pieces also allow for leak detection of the encasement pipe at each end (drawing H-2-829564, sh. 2). The OGT encasement pipeline is supported above ground by adjustable height unistrut brackets and precast concrete bases (drawing H-2-829654, sh. 1). The pipeline is heat-traced and insulated. The heat tracing and insulation supply and retain latent heat that prevents waste solidification during transfers and provides freeze protection. The total length of the pipeline is above ground, thereby negating the need for cathodic corrosion protection. This Construction Integrity Assessment Report (CIAR) is prepared by Fluor Daniel Northwest for Numatec Hanford Corporation/Lockheed Martin Hanford Corporation, the operations contractor, and the U. S. Department of Energy, the system owner. The CIAR is intended to verify that construction was performed in accordance with the provisions of Washington Administrative Code, WAC-173-303-640 (3) (c), (e), (f) and (h). Document type: Report
Abstract
The S-Farm overground transfer (OGT) line will bypass the existing line(s), between valve pits 241-S-B and 241-S-D that no longer meet system requirements. The new OGT line [...]
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Double shell tank emergency pumping guide
M. BROWN

Collection of open reports in transport research (1999). Vol. 1999, 11

Abstract
This Double-Shell Tank Emergency Pumping Guide provides the preplanning necessary to expeditiously remove any waste that may leak from the primary tank to the secondary tank for Hanford's 28 DSTS. The strategy is described, applicable emergency procedures are referenced, and transfer routes and pumping equipment for each tank are identified. Document type: Report
Abstract
This Double-Shell Tank Emergency Pumping Guide provides the preplanning necessary to expeditiously remove any waste that may leak from the primary tank to the secondary tank [...]
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Tank 241er311 interconnected piping and equipment vapor sampling and analysis plan
L. SASAKI

Collection of open reports in transport research (1999). Vol. 1999, 10

Abstract
This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained from piping, equipment, or facilities connected to tank 241-ER-311. The purpose of this sampling event is to obtain information about the effects of the argon purge gas added to tank 241-ER-311. Vapor samples will be taken in the encasement of transfer lines, at the ER-151 diversion box, and, as necessary, any other locations connected to tank 241-ER-311. Combustible gas, ammonia, and organic vapor levels will be field-measured using hand-held instruments. Vapor samples will be taken and shipped to the Pacific Northwest National Laboratory (PNNL) for analysis. This test plan identifies the sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides the requirements for vapor measurements performed in the field. Document type: Report
Abstract
This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements [...]
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Transport of tank 241 sy 101 waste slurry effects of dilution and temperature on critical pipeline velocity
Y. Onishi, K. Recknagle, N. Recknagle, N. Onishi

Collection of open reports in transport research (1999). Vol. 1999, 9

Abstract
This report presents the methods and results of calculations performed to predict the critical velocity and pressure drop required for the two-inch pipeline transfer of solid/liquid waste slurry from underground waste storage Tank 241-SY-101 to Tank 241-SY- 102 at the Hanford Site. The effects of temperature and dilution on the critical velocity were included in the analysis. These analyses show that Tank 241-SY-101 slurry should be diluted with water prior to delivery to Tank 241-SY-102. A dilution ratio of 1:1 is desirable and would allow the waste to be delivered at a critical velocity of 1.5 ft/sec. The system will be operated at a flow velocity of 6 ft/sec or greater therefore, this velocity will be sufficient to maintain a stable slurry delivery through the pipeline. The effect of temperature on the critical velocity is not a limiting factor when the slurry is diluted 1:1 with water. Pressure drop at the critical velocity would be approximately two feet for a 125-ft pipeline (or 250-ft equivalent straight pipeline). At 6 ft/sec, the pressure drop would be 20 feet over a 250-ft equivalent straight pipeline. Document type: Report
Abstract
This report presents the methods and results of calculations performed to predict the critical velocity and pressure drop required for the two-inch pipeline transfer of solid/liquid [...]
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Hazard evaluation for transfer of waste from tank 241 sy 101 to tank 241 sy 102
M. SHULTZ

Collection of open reports in transport research (1999). Vol. 1999, 7

Abstract
Tank 241-SY-101 waste level growth is an emergent, high priority issue. The purpose of this document is to record the hazards evaluation process and document potential hazardous conditions that could lead to the release of radiological and toxicological material from the proposed transfer of a limited quantity (approximately 100,000 gallons) of waste from Tank 241-SY-101 to Tank 241-SY-102. The results of the hazards evaluation were compared to the current Tank Waste Remediation System (TWRS) Basis for Interim Operation (HNF-SD-WM-BIO-001, 1998, Revision 1) to identify any hazardous conditions where Authorization Basis (AB) controls may not be sufficient or may not exist. Comparison to LA-UR-92-3196, A Safety Assessment for Proposed Pump Mixing Operations to Mitigate Episodic Gas Releases in Tank 241-SY-101, was also made in the case of transfer pump removal activities. Revision 1 of this document deletes hazardous conditions no longer applicable to the current waste transfer design and incorporates hazardous conditions related to the use of an above ground pump pit and overground transfer line. This document is not part of the AB and is not a vehicle for requesting authorization of the activity; it is only intended to provide information about the hazardous conditions associated with this activity. The AB Control Decision process will be used to determine the adequacy of controls and whether the proposed activity is within the AB. This hazard evaluation does not constitute an accident analysis. Document type: Report
Abstract
Tank 241-SY-101 waste level growth is an emergent, high priority issue. The purpose of this document is to record the hazards evaluation process and document potential hazardous [...]
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On ACK filtering on a slow reverse channel
C. Barakat, E. Altman

Collection of open reports in transport research (2000). Vol. 2000, 6

Abstract
Acknowledgement (ACK) filtering has been proposed as a technique to alleviate the congestion at the input of a slow channel located on the reverse path of a TCP connection. Old ACKs waiting at the input of the slow channel are erased when new ACKs are to be queued. In the literature the case of one-ACK per connection at a time has been studied. In this paper we show that this is too aggressive for short transfers where ACKs arrive in bursts due to the slow start phase, and where the TCP source needs to receive the maximum number of ACKs to increase fast its window. We study first static filtering where a certain ACK queue length is allowed. We show analytically how this length needs to be chosen. We present then some algorithms that adapt the filtering of ACKs as a function of the slow channel utilization rather than the ACK queue length. These algorithms provide a good compromise between reducing the ACK queueing delay and passing a large number of ACKs that guarantee a fast window increase. Copyright Â© 2003 John Wiley & Sons, Ltd. Document type: Report
Abstract
Acknowledgement (ACK) filtering has been proposed as a technique to alleviate the congestion at the input of a slow channel located on the reverse path of a TCP connection. [...]
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Operational test report for 2706 t complex liquid transfer system
H. BENZEL

Collection of open reports in transport research (1999). Vol. 1999, 6

Abstract
This document is the Operational Test Report (OTR). It enters the Record Copy of the W-259 Operational Test Procedure (HNF-3610) into the document retrieval system. Additionally, the OTR summarizes significant issues associated with testing the 2706-T waste liquid transfer and storage system. Document type: Report
Abstract
This document is the Operational Test Report (OTR). It enters the Record Copy of the W-259 Operational Test Procedure (HNF-3610) into the document retrieval system. Additionally, [...]
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Project design concept for transfer piping for project w 314 tank farm restoration and safe operations
D. MCGREW

Collection of open reports in transport research (1999). Vol. 1999, 5

Abstract
This Project Design Concept represents operational requirements for design of transfer piping system for Phase I of Project W-314, Tank Farm Restoration and Safe Operation Upgrades. Document type: Report
Abstract
This Project Design Concept represents operational requirements for design of transfer piping system for Phase I of Project W-314, Tank Farm Restoration and Safe Operation [...]
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High level waste system process interface description
P. d'Entremont

Collection of open reports in transport research (1999). Vol. 1999, 3

Abstract
The High-Level Waste System is a set of six different processes interconnected by pipelines. These processes function as one large treatment plant that receives, stores, and treats high-level wastes from various generators at SRS and converts them into forms suitable for final disposal. The three major forms are borosilicate glass, which will be eventually disposed of in a Federal Repository, Saltstone to be buried on site, and treated water effluent that is released to the environment. Document type: Report
Abstract
The High-Level Waste System is a set of six different processes interconnected by pipelines. These processes function as one large treatment plant that receives, stores, and [...]
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Installation instructions etn 98 0005 s farm overground transfer ogt system valve pit 241 s b to valve pit 241 s d
D. HICKS

Collection of open reports in transport research (1999). Vol. 1999, 2

Abstract
Lockheed Martin Hanford Corporation (LMHC) is providing an overground transfer (OGT) system for use in saltwell pumping of the 241-S-Tank Farm. Fluor Daniel Northwest (FDNW) was requested to support the effort by completing the design of the OGT system and completing the construction of the encasement pipe and encasement pipe support system. FDNW will also install the concrete shielding blocks for the OGT system. The shielding block system will provide a vehicle barrier for protection of the OGT line and will provide a radiation barrier for operations personnel. LMHC is responsible for the regulatory compliance of the entire transfer system. This installation instruction covers the encasement piping, pipe supports, heat tracing, thermal insulation, leak detectors, temperature indicators, and the shielding blocks. Installation of the primary (inner) pipe and associated equipment was completed at a previous time and the integrity of the primary piping will be confirmed by LMHC prior to operation of the system. Document type: Report
Abstract
Lockheed Martin Hanford Corporation (LMHC) is providing an overground transfer (OGT) system for use in saltwell pumping of the 241-S-Tank Farm. Fluor Daniel Northwest (FDNW) [...]
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The physics of traffic
B. Kerner, A. Grayling

Collection of open chapters of books in transport research (1999). Vol. 1999, 16

Abstract
Traffic jams are a fact of life for many car drivers. Every morning millions of drivers around the world sit motionless in their vehicles for long periods of time as they try to get to work, and then repeat the experience on their journeys home in the evening. The same thing often happens when they are driving to the coast for the weekend or to the airport to go on their holidays. They blame other drivers, increasing volumes of traffic and, inevitably, roadworks. So what has any of this got to do with physics? Document type: Book
Abstract
Traffic jams are a fact of life for many car drivers. Every morning millions of drivers around the world sit motionless in their vehicles for long periods of time as they [...]
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International tourism
W. Lise, F. Spaninks, R. Tol

Collection of open chapters of books in transport research (2000). Vol. 2000, 16

Abstract
56 ???????? ????? ????? "?????????? ???? ? ????? ???????, ??????? ? ???????????? ????" ???????? ???????? ???????????? ???????? ???????? ??????????? ????? ? ?????? ????????????? ??? ???????? ????? ? ????????? ????????????? ??????????? ? ????????????????? ???????. ???????????? ?????????? ???????? ??????????? ????? ??????????????-???????????????? ????????, ??? ???????? ?????????? ??????????? ? ??????????? ?????? ?? ????????????? ?? ?????? ??????? ??????????, ???????????? ?????????? ? ??????????? ????????????????????? ? ??????? ???????? ??????????? ????? ? ????? ??????????????? ? ???????????????? ????????? ? ??????? ???? ?????. Document type: Book
Abstract
56 ???????? ????? ????? "?????????? ???? ? ????? ???????, ??????? ? ???????????? ????" ???????? ???????? ???????????? ???????? ???????? ??????????? ????? ? ?????? ????????????? [...]
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The fairness challenge in computer networks
R. Denda, A. Banchs, W. Effelsberg

Collection of open chapters of books in transport research (2000). Vol. 2000, 15

Abstract
In this paper, the concept of fairness in computer networks is investigated. We motivate the need of examining fairness issues by providing example future application scenarios where fairness support is needed in order to experience sufficient service quality. Fairness definitions from political science and their application to computer networks are described and a state-of-the-art overview of research activities in fairness, from issues such a queue management and tcp-friendliness to issues like fairness in layered multi-rate multicast scenarios, is given. We contribute with this paper to the ongoing research activities by defining the fairness challenge with the purpose of helping direct future investigations to with spots on the map of research in fairness. Document type: Part of book or chapter of book
Abstract
In this paper, the concept of fairness in computer networks is investigated. We motivate the need of examining fairness issues by providing example future application scenarios [...]
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Reforming the Urban Transport Sector in the Rio de Janeiro Metropolitan Region: A Case Study in Concessions
J. Rebelo

Collection of open chapters of books in transport research (1999). Vol. 1999, 14

Abstract
The author describes a bold effort by the state government to increase private sector participation in Rio de Janeiro's urban transport sector, reduce heavy operating subsidies, and establish a foundation for making the sector sustainable. This effort was undertaken with the help of three World Bank-financed loans: * The Rio de Janeiro Metropolitan Transport Loan, which provided assistance for the transfer of federally owned suburban railways to the state government. * The Rio de Janeiro State Reform and Privatization Loan, which helped the state privatize and grant concessions for a number of its enterprises. * The Rio de Janeiro Mass Transit Loan, which supported the reorganization of the sector and the concession of the Rio suburban railways (Flumitrens). Most of the reforms in the urban transport sector have been implemented. The lessons learned from implementation and the results obtained so far suggest that political decisiveness, transparency, and ingenuity in developing incentives are crucial to privatizing urban rail transport systems. But the state also learned that not having a credible staff redundancy program might seriously reduce the benefits expected from concessions. Document type: Book
Abstract
The author describes a bold effort by the state government to increase private sector participation in Rio de Janeiro's urban transport sector, reduce heavy operating subsidies, [...]
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Regulatory reform competition and innovation a case study of the mexican road freight industry
P. Ibarra, A. Hayri, A. Hayri, M. Dutz, M. Dutz, P. Ibarra

Collection of open chapters of books in transport research (1999). Vol. 2000, 10

Abstract
Discussions of competition and regulatory reform typically focus on price and quantity effects. But improving certain infrastructure services can also stimulate entry, and competition in user industries downstream, allowing new firms to enter, incumbent users to offer new products, and rivalry to intensify. The authors present a case study of how innovations in road freight services affect selected downstream users of those services after regulatory reform. After a period of rigid regulation, and heavy government interference, Mexico in 1989 developed a new policy framework for road transport, with free entry, and market-based price setting. The result: faster, more reliable trucking has allowed user companies to offer new, previously unavailable products, and to reach new areas with existing products. Cheaper, more customer-responsive trucking services have allowed logistical innovations in user firms, and some user firms have decided not to keep their own fleets of trucks, but to outsource trucking services on the open market, thereby converting fixed costs to variable costs. For one fertilizer company, the benefits of reform included a ten percent improvement in operating margin. Successful reform requires careful planning and execution, and political support at high levels. Regulatory reform also profoundly changes the sectoral institution formerly responsible for the regulation. Enough resources should be provided to help organizations in the reformed industry make the transition to the post-reform environment - helping with such tasks as defining the organizations new role, and facilitating the redeployment of staff. The national competition agency can help greatly in laying the groundwork for reform by making a compelling case for the reforms expected benefits. After reform, the competition agency should also help with enforcement, to ensure that the cozy, cartel-like behavior stimulated by tight entry restrictions does not persist. In Mexico, three strong interventions were required to discipline attempted anti-competitive practices in the trucking industry in the years following reform. Document type: Book
Abstract
Discussions of competition and regulatory reform typically focus on price and quantity effects. But improving certain infrastructure services can also stimulate entry, and [...]
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Methoden zur Bestimmung der verkehrsbedingten Emissionen von Luftschadstoff: Netzwerk europäischer Wissenschaftler und Stand der Wissenschaften : Schlußbericht der COST-Aktion 319
R. Joumard

Collection of open chapters of books in transport research (1999). Vol. 1999, 8

Abstract
International audience; Dieser Bericht ist das Ergebnis einer Zusammenarbeit von etwa 100 Forschern im Zeitraum von 1993 bis 1998. Die COST Aktion 319 Abschätzung der verkehrsbedingten Schadstoffemissionen fu?hrte dazu, daß ein Netzwerk von Wissenschaftern aufgebaut und Methoden zur Durchfu?hrung von Emissionsberechnungen entwickelt wurden. Zuzätzlich konnte der zuku?nftige Forschungsbedarf auf diesem Bebiet aufgezeigt werden.Das im Rahmen der Aktion entwickelte Netzwerk umfaßt 200 Mitglieder. Die Hälfte von ihnen spielte eine aktive Rolle in den verschiedenen Arbeitsgruppen, die den größten Teil der europäischen Spezialisten auf dem Gebiet der transportbezogenen Emissionserhebungen repräsentieren. Die Adressen und Telefonnummern der Mitglieder des Netzwerks, Forscher oder Anwender, sind einschließlich ihrer fachlichen Schwerpunkte angegeben.Im wissenschaftlichen Teil des Berichts ist der Entwicklungsstand in Europa auf diesem Gebiet dargestellt, wobei in Bezug auf die räumliche Auflösung nach verschiedenen Anwendungsbereichen der Modelle unterschieden wird. Die vier Transportarten - Straße, Schiene, Wasser und Luft - werden behandelt unter Einbeziehung von Teilmodellen, die verschiedene Datensätze von Emissionsfaktoren und Verkehrskenngrößen nutzen, die zunächst analysiert wurden (Analyse der verfu?gbaren Daten, Annahmen, Schlußfolgerungen in bezug auf Modellierung). Die verschiedenen Modelle sind in einem gesonderten Bericht detailliert beschrieben.Schließlich wurde der wichtigste Bedarf an zuku?nftigen Forschungsstudien herausgearbeitet die das Ziel haben, hinreichend genaue und konsistente Modelle zur Erfassung transportbedingter Emissionen zu entwickeln.; The COST 319 action "Estimation of pollutant emissions from transport" involved cooperation between about a hundred European researchers between 1993 and 1998. This report presents the results of the action in terms of network development, inventory methods, and future research needs. The complete Action network had over 200 members. Half of these played an active role in the various working groups. The network included most of the European specialists in the field of transport-related emission inventories. The addresses , phone numbers, and subject areas of the network members, whether they be researchers or users, are included in this report. State-of-the-art European inventorying tools are presented in the report. A distinction has been made, according to the type of application, between disaggregated, central, or aggregated models. The four transport modes - road, rail, sea and air - are addressed using a set of sub-models and databases relating to various emission factors and traffic characteristics. The data used in the models, the assumptions that are made, and the model output are all analysed. The implications for emission modelling are reported. In addition, an assessment was made of the research that would be required in the future to develop sufficiently precise and homogeneous inventorying models for transport-related emissions which could be used in various applications.; Fruit de la collaboration d'une centaine de chercheurs européens de 1993 à 1998, les résultats de l'action COST 319 "Estimation des émissions de polluants par les transports" sont présentés en termes de réseau, de méthodes d'inventaires, et de besoins de recherche future.Le réseau issu de l'action comprend plus de 200 membres dont la moitié a pris une part active dans les différents groupes de travail. Il représente donc l'essentiel des spécialistes européens dans le domaine des inventaires d'émissions des transports. Les coordonnées de chacun des membres, chercheurs ou utilisateurs, sont publiées ainsi que son domaine d'activité.La partie purement scientifique du rapport présente l'état de l'art européen en la matière en distinguant les différent types d'application correspondant à des modèles désagrégés, centraux, et agrégés. Les quatre modes routier, ferré, aérien et maritime-voie d'eau sont traités, avec un ensemble de sous-modèles et de bases de données concernant les différents facteurs d'émission et les caractéristiques du trafic. La mise au point des résultats est analysée en priorité (analyse des données disponibles, hypothèses, conclusions en terme de modélisation), tandis que les différents modèles sont présentés en détail dans un rapport annexe.Enfin les principaux besoins de recherche future ont été analysés, afin de tendre vers des modèles d'inventaire des émissions des transports suffisamment précis et homogènes pour leurs différentes applications. Document type: Book
Abstract
International audience; Dieser Bericht ist das Ergebnis einer Zusammenarbeit von etwa 100 Forschern im Zeitraum von 1993 bis 1998. Die COST Aktion 319 Abschätzung der verkehrsbedingten [...]
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Essentials for sustainable urban transport in brazil s large metropolitan areas
J. Rebelo

Collection of open chapters of books in transport research (1999). Vol. 1999, 3

Abstract
Before financing major urban transport projects, decisionmakers should attempt to put in place the basic elements for long-term sustainability of the sector. Specifically, the author contends that each large metropolitan area in Brazil should incorporate into its urban transport strategy, and pursue vigorously, the following four-point agenda: 1) create a regional transport coordination commission in charge of coordinating policies among federal, state, and municipal governments, giving highest priority to major urban transport investments in the metropolitan region and promoting modal integration - all to the end of improving the sector's economic efficiency and long-term sustainability; 2) adopt an integrated land use, urban transport, and air quality strategy that provides a framework in which the community and decisionmakers can evaluate future urban transport investments and policies; 3) enact into law formal financing mechanisms that would ensure that long-run variable costs of urban transport systems are covered by operating and non-operating revenues from the systems and by appropriate user charges; and 4) promote private sector participation in the operation, maintenance, and construction of urban transport systems - through concessions or management contracts - as a way to lessen the financial burden on the government. Document type: Book
Abstract
Before financing major urban transport projects, decisionmakers should attempt to put in place the basic elements for long-term sustainability of the sector. Specifically, [...]
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Métodos avanzados para el cálculo de la resistencia de la última de estructuras de hormigón
E. Oñate, A. Hanganu

(1999). Research Report, Nº PI176

Abstract
Se presenta en el trabajo una panorámica de los modelos más recientes para evaluar la resistencia última de estructuras de hormigón en masa y armado. Se presta especial atención al modelo de daño, descubriéndose varios ejemplos de aplicación de este modelo.
Abstract
Se presenta en el trabajo una panorámica de los modelos más recientes para evaluar la resistencia última de estructuras de hormigón en masa y armado. [...]
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Adaptive finite element strategies based on error assessment
A. Huerta, A. Rodríguez-Ferran, P. Diez, J. Sarrate

Int. J. Numer. Meth. Engng. (1999). Vol. 46 (10), pp. 1803-1818

Abstract
Two main ingredients are needed for adaptive finite element computations. First, the error of a given solution must be assessed, by means of either error estimators or error indicators. After that, a new spatial discretization must be defined via h, p or r-adaptivity. In principle, any of the approaches for error assessment may be combined with any of the procedures for adapting the discretization. However, some combinations are clearly preferable. The advantages and limitations of the various alternatives are discussed. The most adequate strategies are illustrated by means of several applications in solid mechanics.
Abstract
Two main ingredients are needed for adaptive finite element computations. First, the error of a given solution must be assessed, by means of either error estimators or error [...]
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A unified approach to remeshing strategies for finite element h-adaptivity
P. Diez, A. Huerta

Comput. Methods Appl. Mech. Engrg., (1999). Vol. 176 (1-4), pp. 215-229

Abstract
In h-adaptivity, a remeshing strategy is needed to compute the distribution of required element size using the estimated error distribution. Several authors have introduced different remeshing strategies yielding very different results. In this work these methods are included in a unified framework, emphasizing the role of the underlying hypotheses. Moreover, an objective tool to evaluate the accuracy of the resulting finite element solution is presented. Thus, a new remeshing strategy is introduced to optimize the accuracy of the adapted solutions. The different remeshing strategies are compared with well-known numerical examples.
Abstract
In h-adaptivity, a remeshing strategy is needed to compute the distribution of required element size using the estimated error distribution. Several authors have introduced [...]
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Finite element simulation of the filling of thin moulds
R. Codina, O. Soto

Int. J. Numer. Meth. Engng. (1999). Vol. 46 (9), pp. 1559-1573

Abstract
In this work we present a finite element formulation to simulate the filling of thin moulds. The model has as starting point a 3‐D approach using either div‐stable elements, such as the Q2/P1 element (tri‐quadratic velocities and piecewise linear, discontinuous pressures) or stabilized finite element formulations. The tracking of the free surface is based on the Volume‐Of‐Fluid (VOF) method. The velocity profile is assumed to be parabolic in the direction normal to the mid‐plane, so that one element along the width of the mould is enough to reproduce this profile if this element is quadratic. The velocity is prescribed to zero on the upper and lower surfaces and the normal to the mid‐plane is also prescribed to zero. In the case of div‐stable elements, the pressure profile is prescribed to be constant along the width of the mould. This can be achieved by using as interpolation degrees of freedom the pressure values at the element centroid and its derivatives in the directions tangent and normal to the mid‐plane, and prescribing the latter to zero. No modifications are needed when stabilized formulations are employed. To advance in time the function used in the VOF technique, we use a constant velocity across the width of the mould, which is taken as the projection on the tangent plane of each element of the nodal velocities. This is needed in order to have mass conservation.
Abstract
In this work we present a finite element formulation to simulate the filling of thin moulds. The model has as starting point a 3‐D approach using either div‐stable elements, [...]
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The characteristic‐based‐split procedure: an efficient and accurate algorithm for fluid problems
O. Zienkiewicz, P. Nithiarasu, R. Codina, M. Vázquez, P. Ortiz

Int. J. Numer. Meth. Fluids (1999). Vol. 31 (1), pp. 359-392

Abstract
In 1995 the two senior authors of the present paper introduced a new algorithm designed to replace the Taylor–Galerkin (or Lax–Wendroff) methods, used by them so far in the solution of compressible flow problems. The new algorithm was applicable to a wide variety of situations, including fully incompressible flows and shallow water equations, as well as supersonic and hypersonic situations, and has proved to be always at least as accurate as other algorithms currently used. The algorithm is based on the solution of conservation equations of fluid mechanics to avoid any possibility of spurious solutions that may otherwise result. The main aspect of the procedure is to split the equations into two parts, (1) a part that is a set of simple scalar equations of convective–diffusion type for which it is well known that the characteristic Galerkin procedure yields an optimal solution; and (2) the part where the equations are self‐adjoint and therefore discretized optimally by the Galerkin procedure. It is possible to solve both the first and second parts of the system explicitly, retaining there the time step limitations of the Taylor–Galerkin procedure. But it is also possible to use semi‐implicit processes where in the first part we use a much bigger time step generally governed by the Peclet number of the system while the second part is solved implicitly and is unconditionally stable. It turns out that the characteristic‐based‐split (CBS) process allows equal interpolation to be used for all system variables without difficulties when the incompressible or nearly incompressible stage is reached. It is hoped that the paper will help to make the algorithm more widely available and understood by the profession and that its advantages can be widely realised.
Abstract
In 1995 the two senior authors of the present paper introduced a new algorithm designed to replace the Taylor–Galerkin (or Lax–Wendroff) methods, used by them [...]
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Finite element implementation of two‐equation and algebraic stress turbulence models for steady incompressible flows
R. Codina, O. Soto

Int. J. Numer. Meth. Fluids (1999). Vol. 30 (3), 309-334

Abstract
The main purpose of this paper is to describe a finite element formulation for solving the equations for k and ε of the classical k–ε turbulence model, or any other two‐equation model. The finite element discretization is based on the SUPG method together with a discontinuity capturing technique to deal with sharp internal and boundary layers. The iterative strategy consists of several nested loops, the outermost being the linearization of the Navier–Stokes equations. The basic k–ε model is used for the implementation of an algebraic stress model that is able to account for the effects of rotation. Some numerical examples are presented in order to show the performance of the proposed scheme for simulating directly steady flows, without the need of reaching the steady state through a transient evolution.
Abstract
The main purpose of this paper is to describe a finite element formulation for solving the equations for k and ε of the classical k–ε [...]
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A fractional-step finite-element method for the Navier–Stokes equations applied to magma-chamber withdrawal
R. Folch, M. Vázquez, R. Codina, J. Martí i Castell

Computers and Geotechnics (1999). Vol. 25 (3), pp. 263-275

Abstract
We develop an algorithm to solve numerically the Navier–Stokes equations using a finite element method. The algorithm uses a fractional step approach that allows the use of equal interpolation spaces for the pressure and velocity fields and can be used to solve both compressible and incompressible flows. The standard Galerkin method is used to space-discretize the equations in which convective terms are dominant because the equations are reformulated in a characteristics co-moving frame providing thus the required artificial diffusion in a consistent way. The algorithm depends on four different parameters. Depending on their values, a fully implicit, a semi-implicit or a fully explicit solution can be obtained. The proposed algorithm may be useful in solving a wide spectrum of problems in geology, engineering and geosciences. Several flows frequently encountered in practical applications such as incompressible, slightly compressible or perfect gas are taken into account. As an example, we use it to model the withdrawal of magma from shallow chambers during explosive volcanic eruptions. Our model constitutes a first attempt to characterize the temporal evolution of the most revelant physical parameters during such a process.
Abstract
We develop an algorithm to solve numerically the Navier–Stokes equations using a finite element method. The algorithm uses a fractional step approach that allows [...]
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Numerical solution of the incompressible Navier–Stokes equations with Coriolis forces based on the discretization of the total time derivative.
R. Codina

Journal of Computational Physics (1999). Vol. 148 (2), pp. 467-496

Abstract
In this paper we present a numerical formulation to solve the incompressible Navier–Stokes equations written in a rotating frame of reference. The method is based on a finite difference discretization in time and a finite element discretization in space. When the viscosity is very small, numerical oscillations may appear due both to the high Reynolds number and to the presence of the Coriolis forces. To overcome these oscillations, a special discretization in time is proposed. The idea is to discretize the total time derivative in an inertial basis rather than only the partial time derivative in the rotating reference system. After this is done, a further high-order approximation is introduced, leading to a problem posed in the rotating frame of reference and in spatial coordinates. In contrast with the straightforward discretization of the original equations, some additional terms appear that enhance the stability of the numerical scheme. In the absence of Coriolis forces, the method is a generalization of the characteristic Galerkin technique for convection-dominated flows.
Abstract
In this paper we present a numerical formulation to solve the incompressible Navier–Stokes equations written in a rotating frame of reference. The method is based on [...]
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On the numerical modeling of frictional wear phenomena
C. Agelet de Saracibar, M. Chiumenti

Comput. Methods Appl. Mech. Engrg., (1999). Vol. 177 (3-4), pp. 401-426

Abstract
The evolution of the contact surfaces wear may become particularly important in the definition of the frictional behavior, in particular for frictional contact problems involving large slips, typically in sheet metal forming and bulk forming operations. Despite this fact, most of the current applications reported in the literature are restricted to a standard Coulomb law, using a constant friction coefficient. Such simple models may represent only a limited range of tribological situations and it appears to be necessary to develop a class of models which incorporate the state conditions and their evolution at the contact surfaces, taking into account the influence of complex phenomena such as wear, lubrication and chemical reactions, among others, see Oden and Martins [1]. In this paper a simple numerical model for the simulation of frictional wear behavior, within a fully nonlinear setting, including large slip and finite deformation, is presented. The model relies on the introduction of an internal variable related to the state conditions at the contact surface. Here, two possible definitions of this internal variable have been considered. The fully nonlinear frictional contact formulation, entirely derived first on a continuum setting by Laursen and Simo [2–6], has been extended here to accomodate the characterization of the wear frictional behavior. Within the computational aspects, two families of robust time stepping algorithms, arising from an operator split of the constrained frictional evolution equations, are discussed. Finally, following current approaches, see Lassen [9], Lassen and Bay [10], Owen et al. [11], de Souza et al. [12], Stromberg et al. [13] and Stromberg [14], a long-term tools wear prediction is given by introducing an a priori wear estimate derived from Archard's law, Archard [15]. The numerical model has been implemented into a enhanced version of the computational finite element program FEAP. Numerical examples show the suitability of the proposed model to capture the essential features of the frictional behavior at the contact interfaces and to provide a prediction of tool wear in forming operations.
Abstract
The evolution of the contact surfaces wear may become particularly important in the definition of the frictional behavior, in particular for frictional contact problems involving [...]
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A stabilized finite element method for generalized stationary incompressible flows
R. Codina

(1999). Research Report, Nº PI148

Abstract
In this paper we describe a finite element formulation for the numerical solution of the stationary Navier-Stokes equations including Coriolis forces and the permeability of the medium. The stabilized method is based on the algebraic version of the sub-grid scale approach. We first describe this technique for general systems of convection-diffusion-reaction equations and then we apply it to linearized flow equations. The important point is the design of the matrix of stabilization parameters that the method has. This design is based on the identification of the stability problems of the Galerkin method and a scaling of variables argument to determine which coefficients must be included in the stabilization matrix. This, together with the convergence analysis of the linearized problem, leads to a simple expression for the stabilization parameters in the general situation considered in the paper. The numerical analysis of the linearized problem also shows that the method has optimal convergence properties.
Abstract
In this paper we describe a finite element formulation for the numerical solution of the stationary Navier-Stokes equations including Coriolis forces and the permeability [...]
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Rotation‐free triangular plate and shell elements
E. Oñate, F. Zárate

(1999). Research Report, Nº PI149

Abstract
The paper describes how the finite element method and the finite volume method can be successfully combined to derive two new families of thin plate and shell triangles with translational degrees of freedom as the only nodal variables. The simplest elements of the two families based on combining a linear interpolation of displacements with cell centred and cell vertex finite volume schemes are presented in detail. Examples of the good performance of the new rotation‐free plate and shell triangles are given.
Abstract
The paper describes how the finite element method and the finite volume method can be successfully combined to derive two new families of thin plate and shell triangles with [...]
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A stabilized finite element method for incompressible viscous flows using a finite increment calculus formulation
E. Oñate

(1999). Research Report, Nº PI150

Abstract
A stabilized finite element formulation for incompressible viscous flows is derived. The starting point are the modified Navier-Stokes equations incorporating naturally the necessary stabilization terms via a finite increment calculus (FIC) procedure. Application of the standard finite element Galerkin method to the modified differential equations leads to a stabilized discrete system of equations overcoming the numerical instabilities emanating from the advective terms and those due to the lack of compatibility between approximate velocity and pressure fields. The FIC method also provides a natural explanation for the stabilization terms appearing in all equations for both the Navier-Stokes and the simpler Stokes equations. Transient solution schemes with enhanced stabilization properties are also proposed. Finally a procedure for computing the stabilization parameters is presented.
Abstract
A stabilized finite element formulation for incompressible viscous flows is derived. The starting point are the modified Navier-Stokes equations incorporating naturally the [...]
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Numerical differentiation for Non-Trivial consistent tangent matrices: An application to the MRS-Lade model
A. Pérez-Foguet, A. Rodríguez-Ferran, A. Huerta

(1999). Research Report, Nº PI151

Abstract
In Reference the authors have shown that numerical differentiation is a competitive alternative to analytical derivatives for the computation of consistent tangent matrices. Relatively simple models were treated in that reference. The approach is extended here to a complex model: the MRS-Lade model. This plastic model has a cone-cap yield surface and exhibits strong coupling between the flow vector and the hardening moduli. Because of this, derivating these quantities with respect to stresses and internal variables –crucial step in obtaining consistent tangent matrices- is rather involved. Numerical differentiation is used here to approximate these derivatives. The approximated derivatives are then used 1) to compute consistent tangent matrices (global problem) and 2) to integrate the constitutive equation at each Gauss point (local problem) with the Newton-Raphson method. The choice of the stepsize (i.e. the perturbation in the approximation schemes), based on the concept of relative stepsize, poses no difficulties. In contrast to previous approaches the global problems. The computational efficiency (CPU time) and robustness of the proposed approach is illustrated by means of several numerical examples, where the major relevant topics are discussed in details.
Abstract
In Reference the authors have shown that numerical differentiation is a competitive alternative to analytical derivatives for the computation of consistent tangent matrices. [...]
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Thermo‐mechanical analysis of industrial solidification processes
M. Cervera, C. Agelet de Saracibar, M. Chiumenti

(1999). Research Report, Nº PI153

Abstract
The paper presents an up‐to‐date finite element numerical model for fully coupled thermo‐mechanical problems, focussing in the simulation of solidification processes of industrial metal parts. The proposed constitutive model is defined by a thermo‐visco‐elasto‐(visco)plastic free energy function which includes a contribution for thermal multiphase changes. Mechanical and thermal properties are assumed to be temperature‐dependent, and viscous‐like strains are introduced to account for the variation of the elastic moduli during the cooling process. The continuous transition between the initial fluid‐like and the final solid‐like behaviour of the part is modelled by considering separate viscous and elasto‐plastic responses as a function of the solid fraction. Thermo‐mechanical contact conditions between the mould and the part are specifically considered, assuming that the heat flux is a function of the normal pressure and the thermal and mechanical gaps. A fractional step method arising from an operator split of the governing equations is used to solve the non‐linear coupled system of equations, leading to a staggered product formula solution algorithm suitable for large‐scale computations. Representative simulations of industrial solidification processes are shown, and comparison of computed results using the proposed model with available experimental data is given.
Abstract
The paper presents an up‐to‐date finite element numerical model for fully coupled thermo‐mechanical problems, focussing in the simulation of solidification processes [...]
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New degrees of freedom in computational mechanics: mesh free finite point method, rotation free shell triangles and moving free meshes
E. Oñate

(1999). Research Report, Nº PI154

Abstract
The paper presents an overview of some recent developments in computational mechanics introducing new degrees of “freedom” allowing the solution of more challenging problems. First advances in the finite point method for fully mesh free solution in fluid and solid mechanics are described. Next, new rotation free shell triangles incorporating membrane and bending effects are presented. Finally, a simple method allowing free movement of meshes is described. Examples of application of all the “free” methods are given.
Abstract
The paper presents an overview of some recent developments in computational mechanics introducing new degrees of “freedom” allowing the solution of more challenging [...]
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A nodal-based implementation of a stabilized Finite Element Method for Incompressible Flow Problems
R. Codina

(1999). Research Report, Nº PI156

Abstract
The objective of this paper is twofold. First, a stabilized finite element method for the incompressible Navier-Stokes is presented, and several numerical experiments are conducted to check its performance. This method is able to deal with all the instabilities that the standard Galerkin method presents, namely, the pressure instability, the instability arising in convection dominated situations and also the less popular instabilities found when the Navier-Stokes equations have a dominant Coriolis force, or there is a dominant absorption term arising from the small permeability of the medium where the flow takes place. The second objective is to describe a nodal-based implementation of the finite element formulation introduced. This implementation is based on an a priori calculation of the integrals appearing in the formulation and then the construction of the matrix approximations, this matrix and this vector can be constructed directly for each nodal point, without the need to loop over element and thus making the calculations much faster. In order to be able to do this, all the variables have to be defined at the nodes of the finite element mesh, not on the elements. This is also so for the stabilization parameters of the formulation. However, doing this given rise to questions regarding the consistency and the conservation properties of the final scheme that are addressed in this paper.
Abstract
The objective of this paper is twofold. First, a stabilized finite element method for the incompressible Navier-Stokes is presented, and several numerical experiments are [...]
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Simulation of Construction of RCC Dams. I: Temperature and Aging
M. Cervera, J. Oliver, T. Prato

(1999). Research Report, Nº PI157

Abstract
In this work a numerical procedure for the simulation of the construction process of Roller Compacted Concrete (RCC) dams is described. The basis of the work is a coupled thermos-chemo-mechanical model for the behaviour of concrete at early ages that allows to simulate the observed phenomena of hydration, aging, creep and damage. In this first part only the thermochemical aspects of the simulation of the construction process are presented. The proposed procedure can accurately predict the evolution in time of the hydration degree and the hydration heat production. This allows to obtain the temperature field inside the dam at any time during the construction and the following years. The evolution of the compressive and tensile strengths and elastic moduli can also be predicted in terms of the evolutions of the hydration degree and the temperature conditions. Results from 2d and simplified vertical 1D models are compared and several parametric studies are carried out. The simulation and discussion of the mechanical aspects of the construction process are relegated to a companion paper that follows.
Abstract
In this work a numerical procedure for the simulation of the construction process of Roller Compacted Concrete (RCC) dams is described. The basis of the work is a coupled [...]
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BLAY3D: 3D boundary layer code. User's guide.
M. Storti

(1999). Research Report, Nº PI158

Abstract
This is the user’s guide for the BLAY3D code (version 2.2 of December 28, 1998). BLAY3D is a fluid mechanics code for solving the incompressible Boundary Layer Equations (BLE), based on a spectral approximation in the transversal direction and a mesh-less approximation on the surface of the body. It contains a basic description of what are the BLE, the governing equations involved, how they are solved, which is the data and how is it entered in order to be processed by BLAY3D, what kind of result BLAY3D generates, and finally several examples are shown.
Abstract
This is the user’s guide for the BLAY3D code (version 2.2 of December 28, 1998). BLAY3D is a fluid mechanics code for solving the incompressible Boundary Layer Equations [...]
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Transferencia de calor por conducción. Verificación del programa ED-Poiss
S. Robles, F. Zárate

(1999). Research Report, Nº PI161
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Stabilization of incompressibility and convection through orthogonal sub-scale in finite element methods
R. Codina

(1999). Research Report, Nº PI162

Abstract
Two apparently different forms of dealing with the numerical instability due to the incompressibility constraint of the stokes problem are analyzed in this paper. The first of them is the stabilization thought the pressure gradient projection, which consists of adding a certain least-squares form of the difference between the pressure gradient and its L² projection onto the discrete velocity space in the variational equations of the problem. The second is a sub-grid scale method, whose stabilization effect is very similar to that of the Galerkin/least-squares method for the Stokes problem. It is shown here that the first method can also be recast in the framework of sub-grid scale method with a particular choice for the space of sub-scales. This leads to a new stabilization procedure, whose applicability to stabilize convection is also studied in this paper.
Abstract
Two apparently different forms of dealing with the numerical instability due to the incompressibility constraint of the stokes problem are analyzed in this paper. The first [...]
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On the constitutive modeling of coupled thermomechanical phase-change problems
C. Agelet de Saracibar, M. Cervera, M. Chiumenti

(1999). Research Report, Nº PI163

Abstract
This paper deals with a thermodynamically consistent numerical formulation for coupled thermoplastic problems including phase-change phenomena and frictional contact. The final goal is to get an accurate, efficient and robust numerical model, able for the numerical simulation of industrial solidification processes. Some of the current issues addressed in the paper are the following. A fractional step method arising from an operator split of the governing differential equations has been used to solve the nonlinear coupled system of equations, leading to a staggered product formula solution algorithm. Nonlinear stability issues are discussed and isentropic and isothermal operator splits are formulated. Within the isentropic split, a strong operator split design constraint is introduced, by requiring that the elastic and plastic entropy, as well as the phase-change induced elastic entropy due to the latent heat, remain fixed in the mechanical problem. The formulation of the model has been consistently derived within a thermodynamic framework. All the material properties have been considered to be temperature dependent. The constitutive behavior has been defined by a thermoviscous/elastoplastic free energy function, including a thermal multiphase change contribution. Plastic response has been modeled by a J2 temperature dependent model, including plastic hardening and thermal softening. The constitutive model proposed accounts for a continuous transition between the initial liquid state, the intermediate mushy state and the final solid state taking place in a solidification process. In particular, a pure viscous deviatoric model has been used at the initial fluid-like state. A thermomecanical contact model, including a frictional hardening and temperature dependent coupled potential, is derived within a fully consistent thermodinamical theory. The numerical model has been implemented into the computational finite element code COMET developed by the authors. Numerical simulations of solidification processes show the good performance of the computational model developed.
Abstract
This paper deals with a thermodynamically consistent numerical formulation for coupled thermoplastic problems including phase-change phenomena and frictional contact. The [...]
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Advances in the stabilized finite point method for structural mechanics
E. Oñate, F. Perazzo, J. Canet

(1999). Research Report, Nº PI164

Abstract
The basis of the finite point method for the fully meshless solution of structure mechanics problems is described. A new stabilization technique based on a finite increment calculus procedure is used. The efficiency and accuracy of the stabilized finite point method in the meshless analysis of simple structural problems is shown in two examples of applications.
Abstract
The basis of the finite point method for the fully meshless solution of structure mechanics problems is described. A new stabilization technique based on a finite increment [...]
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A methodology for analysis of fluid structure interaction accouting for free surface waves
E. Oñate, J. García-Espinosa

(1999). Research Report, Nº PI166

Abstract
A stabilized semi-implicit frictional step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized equations are derived at a differential level via a finite element calculus procedure. A new mesh updating technique based on solving a fictitious elastic problem on the moving mesh is described. One example of the efficiency of the stabilized semi-implicit algorithm for the coupled solution of fluid-structure interaction problems is presented.
Abstract
A stabilized semi-implicit frictional step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized [...]
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