Documents published in 2000 : Scipedia

Pipeline Inspection and Rehabilitation Using Clock Spring®
J. Mitchell, P. Porter

Collection of open conferences in research transport (2000). Vol. 2000, 28

Abstract
This paper reviews the Clock Spring® repair system showing how it works and how it can be an effective component of a pipeline integrity program. It also outlines a Pipeline Integrity Program that is effective for TEPPCO and can be helpful to pipeline operators in the development of other pipeline integrity programs."/jats:p" "jats:p"Using high-resolution magnetic flux leakage inspection tools and the Clock Spring® pipeline repair system, TEPPCO’s ten-year pipeline integrity program is ahead of schedule and significantly under budget. The use of advanced technology, combined with efficient planning, has yielded a unique systematic approach to pipeline integrity enhancement.
Abstract
This paper reviews the Clock Spring® repair system showing how it works and how it can be an effective component of a pipeline integrity program. It also outlines a Pipeline [...]
- 0
- read
The Effect of Microstructural Change on Fracture Behavior in Heat-Affected Zone of API 5L X65 Pipeline Steel
J. Ju, D. Kwon, J. Jang, W. Kim

Collection of open conferences in research transport (2000). Vol. 2000, 27

Abstract
Reliability evaluation of welded structures by mechanical testing of weld heat-affected zones (HAZs) has become general practice throughout the world. HAZs of steel welded joints show a gradient of microstructure from the fusion line to the unaffected base metal. This study is concerned with a correlation between the microstructural change and the fracture characteristics in HAZs of both seam and girth welds of API 5L X65 pipeline steel, which is generally used for natural gas transmission pipelines in Korea. The focus in present study was the investigation of macroscopic fracture behavior of the various regions within HAZ. Changes in microstructure and impact toughness were observed using synthetic HAZ specimens as well as actual HAZ specimens. To evaluate the macroscopic toughness of actual HAZ, Charpy V-notch impact test was performed.
Abstract
Reliability evaluation of welded structures by mechanical testing of weld heat-affected zones (HAZs) has become general practice throughout the world. HAZs of steel welded [...]
- 0
- read
New Design Concepts for Pipelines Buried in Permafrost
J. Greenslade, D. Nixon

Collection of open conferences in research transport (2000). Vol. 2000, 26

Abstract
This paper outlines some of the recent design developments and construction support efforts of the authors and their colleagues that reduce the capital cost and enhance the design integrity and environmental performance of pipelines buried in permafrost."/jats:p" "jats:p"These new design concepts can significantly reduce the expected cost of a major northern gas pipeline relative to historical conceptual costs."/jats:p" "jats:p"Recent North Slope of Alaska oil developments have successfully utilized new design concepts for warm buried crossings of major rivers to achieve certain environmental and economic objectives. The fully buried oil pipeline from Normal Wells, NWT, originally designed as a cold pipeline, has successfully operated in recent years as an ambient temperature system. These developments widen the application and improve the potential cost advantage of buried oil pipelines over above grade pipelines in permafrost.
Abstract
This paper outlines some of the recent design developments and construction support efforts of the authors and their colleagues that reduce the capital cost and enhance the [...]
- 0
- read
High Strength Linepipe: Current and Future Production
M. Kostic, L. Collins, R. Mackenzie, N. Townley, T. Lawrence

Collection of open conferences in research transport (2000). Vol. 2000, 25

Abstract
Recent construction of pipelines in Canada has seen a trend towards higher operating pressures with greater wall thicknesses and/or higher strength pipe. At the same time, Grade 550 linepipe is becoming accepted as the standard for new construction. The production of high strength grades in wall thicknesses over 12.5 mm presents a new challenge. The increased wall thickness and higher strengths tax manufacturing equipment to the fullest. IPSCO has recently completed the production of 1150 km of 14.2 mm spiral-welded Grade 483 linepipe for the Alliance Pipeline. This paper will examine the technical issues associated with the production of this pipe at the Regina steel mill. Successful production trials at IPSCO’s new steel mill in Montpelier, Iowa, which incorporates new process technology, are also described. Production of linepipe with strength exceeding 550 MPa will also be examined.
Abstract
Recent construction of pipelines in Canada has seen a trend towards higher operating pressures with greater wall thicknesses and/or higher strength pipe. At the same time, [...]
- 0
- read
The Application of the Battelle “Short Formula” to the Determination of Ductile Fracture Arrest Toughness in Gas Pipelines
A. Rothwell

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

Abstract
Many models and formulae have been put forward, over the years, for the determination of the toughness necessary for the arrest of propagating ductile fracture in gas pipelines. One of the first, and most prominent, was that developed by Battelle Columbus Laboratories for the Pipeline Research Committee of the American Gas Association. As originally embodied, the model involved the comparison of curves expressing the variation of fracture velocity and of decompression wave velocity with pressure (the “two-curve model” — TCM). To aid in analysis, at a time long before a computer was available on every desk, a “short formula” (SF) was developed that provided a good fit to the results of the TCM for a substantial matrix of conditions. This SF has subsequently been adopted by several standards bodies and used widely in the analysis of the results of full-scale burst tests. Since the original description of the derivation of the SF is to be found only in a report to the PRC dating back to the Seventies, many in the pipeline industry today are left without a full appreciation of its range of validity. The present paper briefly discusses the original intent of the SF as a substitute for the TCM, and presents the results of extensive calculations comparing the results of the two. It can be concluded that the SF provides an excellent estimate of the results of the TCM over a very wide range of design and operating parameters, within the limitations inherent in the method.Copyright © 2000 by ASME
Abstract
Many models and formulae have been put forward, over the years, for the determination of the toughness necessary for the arrest of propagating ductile fracture in gas pipelines. [...]
- 1
- read
Multi-Pipeline Geographical Information System Based on High Accuracy Inertial Surveys
H. Pino, R. Gomez, J. Czyz, C. Pettigrew

Collection of open conferences in research transport (2000). Vol. 2000, 23

Abstract
This paper describes the GIS system developed for the Pemex’ pipeline network in the Valley of Mexico. The pipeline UTM coordinates, which are the basis of the GIS, were obtained from the high accuracy Geopig® inertial and caliper surveys. The survey data also included information on pipeline features and anomalies, and was incorporated into the GIS together with the metal loss data from the past in-line inspections. The system is based on the ArcView® GIS Software with the Arc View 3D Analyst™ extension that allows both the cartography and pipeline data to be viewed in 3-D space. It stores information on pipeline plan, profile, girth weld locations, dents, wall thickness, bending strains, metal loss and other features in relation to known landmarks such as roads, buildings, political boundaries and hydrology. This allows for very efficient and accurate location of pipe defects and anomalies, which is particularly beneficial where there are several pipelines running in the same right-of-way. It helps to eliminate unnecessary excavations, as well as to coordinate, plan and schedule pipeline repairs. The additional benefit of a multi-pipeline GIS system is the ability to store various information for all the pipelines in one database, which is easy to manage and update. The GIS also gives the ability to plot detailed maps, query data for effective solutions and visualize scenarios.Copyright © 2000 by ASME
Abstract
This paper describes the GIS system developed for the Pemex’ pipeline network in the Valley of Mexico. The pipeline UTM coordinates, which are the basis of the GIS, were [...]
- 0
- read
The Resistance of Advanced Pipeline Coatings to Penetration and Abrasion by Hard Rock
P. Singh, A. Williamson, J. Hancock

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

Abstract
The resistance to rock penetration and abrasion damage of four advanced pipeline anti-corrosion coatings on buried steel linepipe was quantified by means of controlled pipe burial tests. Production-coated steel linepipes were buried in three different gradations of crushed hard rock, and a Caterpillar 966D wheel loader was driven directly over the buried pipes twice daily for 12 consecutive days. Subsequent excavation and inspection of the pipes showed that the coatings experienced progressively more damage (quantified by the number of holidays) with increase in rock size and progressively less damage with increase in coating thickness. A quantitative relationship between coating damage and coating thickness was defined for the two larger rock sizes.Copyright © 2000 by ASME
Abstract
The resistance to rock penetration and abrasion damage of four advanced pipeline anti-corrosion coatings on buried steel linepipe was quantified by means of controlled pipe [...]
- 0
- read
New Technical and Economic Solutions for Gas Exploitation in the Amazon Region (Peru-Brazil Pipeline)
G. Carrera, E. Santos

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

Abstract
The Amazon region has been demonstrating a great oil and gas potential in Brazil and in the neighboring countries, specially the field of Camisea in Peru. However, the development of feasible and economically justifiable transport systems, that can allow the flow of those resources to their potential markets, continues to be the great challenge. In this work, we present some options that can be transformed into competitive and commercial projects. We describe different gas pipeline options, discussing their technical, economic and commercial aspects.Copyright © 2000 by ASME
Abstract
The Amazon region has been demonstrating a great oil and gas potential in Brazil and in the neighboring countries, specially the field of Camisea in Peru. However, the development [...]
- 0
- read
Challenges in the Development of Market-Based Pipeline Investments
G. Bassenheim, A. Jenkins, D. Klaudt, M. Mohitpour

Collection of open conferences in research transport (2000). Vol. 2000, 20

Abstract
Market-based pipeline projects are initiated by the pipeline-owning company and require focused attempts to secure a customer or develop a market for the product transportation."/jats:p" "jats:p"The development of Market-based pipeline investments in the international arena has fundamental differences from projects sponsored by consumer or pipeline user needs, government endeavors or producers desiring to sell their product. Whereas these User-driven projects were the traditional way of developing projects in the past, current global political and economical trends are forcing private pipeline companies to develop new ways of creating business opportunities: the development of Market-based Pipeline Projects."/jats:p" "jats:p"A proactive strategy for developing energy transmission businesses (i.e. market-based projects) involves finding sufficient energy users and linking them with pipeline infrastructure to viable supplies of natural gas. These Market-based business opportunities are uniquely developed and require strong corporate vision and support before it can be successfully implemented."/jats:p" "jats:p"This paper will provide an insight to the challenges, risks and uncertainties to be faced when developing Market-based pipeline projects. The discussion focuses on the project development phase of the project, from the moment the business opportunity viability has been confirmed to the time when the decision is made to proceed with large capital commitments. The paper includes a description of the pipeline project development process and a review of the variables influencing important steps and decisions prior to commencement of project implementation and hence capital investments."/jats:p" "jats:p"While the content of this paper is mostly applicable to all types of pipeline projects, the discussion will focus on natural gas transmission pipelines.
Abstract
Market-based pipeline projects are initiated by the pipeline-owning company and require focused attempts to secure a customer or develop a market for the product transportation."/jats:p" [...]
- 0
- read
Physical Forces on Buried Pipeline Coatings
G. King

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

Abstract
Physical forces activated when buried pipelines move relative to the soil can damage coatings. The problem is most common near bends and areas with poor backfill compaction. Most solutions are best implemented early in the design work when pipeline routes, alignments, and operating conditions are being selected. Solutions, in addition to the obvious one of increasing toughness and adhesion of coatings, include increasing radius of bends, avoiding unstable slopes, improving backfill operations, stabilizing operating conditions, and reducing operating pressures and temperatures.Copyright © 2000 by ASME
Abstract
Physical forces activated when buried pipelines move relative to the soil can damage coatings. The problem is most common near bends and areas with poor backfill compaction. [...]
- 0
- read
Modeling of Buried Natural Gas Pipeline Decompression
G. King, X. Zhou, R. Moore

Collection of open conferences in research transport (2000). Vol. 2000, 18

Abstract
pseudo-homogeneous multi-component equilibrium model is developed to study fluid flow behavior and heat transfer during decompression of a buried natural gas pipeline. The model includes non-isentropic effects of heat transfer and viscous dissipation. The heat transfer involves transient heat conduction through the pipe wall and the soil. A numerical scheme is developed to efficiently solve the resulting conservation equations simultaneously with the heat transfer equation. The study shows that the inclusion of transient heat transfer is necessary for accurate modeling the decompression of natural gas pipelines. The temperature reduction on the pipe wall due to fluid expansion can be crucial for the proper design of pipelines to prevent brittle behavior of the pipe steel.Copyright © 2000 by ASME
Abstract
pseudo-homogeneous multi-component equilibrium model is developed to study fluid flow behavior and heat transfer during decompression of a buried natural gas pipeline. The [...]
- 0
- read
Responding to a Northern Pipeline Challenge
T. Klatt

Collection of open conferences in research transport (2000). Vol. 2000, 17

Abstract
n 800-mile natural gas pipeline is being considered as part of an Alaskan liquefied natural gas (LNG) project. Concepts to maximize the pipeline’s value and minimize its cost are considered. The pipeline’s operating pressure has been synchronized with the LNG plant’s inlet pressure to achieve system efficiencies. Line pipe steels are optimized to address pressure, fracture and geotechnical issues. An advanced approach to designing and operating a gas pipeline in discontinuous permafrost is evaluated. Construction methods and strategies have been developed in areas such as trenching and winter construction. Finally, future work to further develop these concepts is identified.Copyright © 2000 by ASME
Abstract
n 800-mile natural gas pipeline is being considered as part of an Alaskan liquefied natural gas (LNG) project. Concepts to maximize the pipeline’s value and minimize its [...]
- 0
- read
Northstar Development Pipelines Limit State Design and Experimental Program
A. Nogueira, G. Lanan, T. Even, B. Hormberg, J. Fowler

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

Abstract
BP Exploration (Alaska) Inc. (BPXA) and its Northstar Project Alliance contractors started field construction of the Northstar development in January 2000 (Lanan et al. 2000). In April 2000, the offshore section of the Northstar pipeline reached Seal Island, located in 11 m water depth Northwest of Prudhoe Bay. Seal Island is in the Beaufort Sea, 9.7 km offshore from the shore crossing at Point Storkersen, on the North Slope of Alaska. Design, testing and permitting activities required multiple years leading up to this first of it kind pipeline construction project. Figure 1 shows the offshore pipeline welding spread working on the floating sea ice surface, similar to the conventional procedures used on the overland portion of the Northstar pipeline. This paper presents the limit state design of the offshore pipelines and the associated full-scale experimental program, which demonstrated that the pipelines can safely withstand operational bending strains up to 1.8%.Copyright © 2000 by ASME
Abstract
BP Exploration (Alaska) Inc. (BPXA) and its Northstar Project Alliance contractors started field construction of the Northstar development in January 2000 (Lanan et al. 2000). [...]
- 0
- read
Validation of an In-Line Inspection Metal Loss Tool
A. Bhatia, T. Morrison, N. Mangat, G. Desjardins

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

Abstract
Enbridge Pipelines Inc. (“Enbridge”), together with U.S. affiliate Lakehead Pipe Line, operates the world’s longest crude oil and petroleum products pipeline system. These companies transport liquid hydrocarbons from their point of supply to refining markets in the Midwestern United States and Eastern Canada.Copyright © 2000 by ASME
Abstract
Enbridge Pipelines Inc. (“Enbridge”), together with U.S. affiliate Lakehead Pipe Line, operates the world’s longest crude oil and petroleum products pipeline system. [...]
- 1
- read
Enhanced Pipeline Integrity at Lower Cost: A Pipeline Integrity Prioritization Model
R. Burdylo, A. Aelst

Collection of open conferences in research transport (2000). Vol. 2000, 14

Abstract
Strategic, focussed application of pipeline integrity monitoring and mitigation techniques will significantly improve pipeline integrity program effectiveness while reducing overall maintenance costs. These achievements have been demonstrated through the development of Maintenance Prioritization Models (MPM) that pinpoint areas along the pipeline with the highest susceptibility to failure and identify the most cost effective mitigation strategy."/jats:p" "jats:p"A MPM identifies areas along the pipeline that exhibit a higher relative susceptibility to failure and consequence in the event of a pipeline rupture. Used as part of the owner’s pipeline integrity management program, it assists with optimization, planning and focusing of integrity related preventative maintenance activities. Areas that require short-term mitigation are identified and maintenance budgeting and planning can be prioritized while long-term planning needs are forecast. It enables integrity engineers to manage resources more efficiently by focusing on areas of highest need, thereby extending the useful life of the pipeline section that will, in turn, extend its revenue generation capabilities.
Abstract
Strategic, focussed application of pipeline integrity monitoring and mitigation techniques will significantly improve pipeline integrity program effectiveness while reducing [...]
- 0
- read
An Interim Approach to Determine Dynamic Ductile Fracture Resistance of Modern High Toughness Pipeline Steels
N. Pussegoda, L. Malik, A. Rothwell, A. Dinovitzer, B. Graville

Collection of open conferences in research transport (2000). Vol. 2000, 13

Abstract
The ductile fracture toughness of steel is used to assess the ability of a pipeline to resist long running ductile fractures in a burst event. In modern low carbon clean steels with high toughness, conventional measures of ductile fracture toughness (standard Charpy and DWTT energy) are under review, and alternatives are being studied. The major factor causing concern is the inability of these tests to isolate the energy associated with crack propagation from the total energy absorbed during the specimen fracture. This is significant in modern high toughness steels because their initiation toughness is extremely high."/jats:p" "jats:p"To resolve crack propagation energy, a novel modification was evaluated for both Charpy and DWTT specimens by employing a back-slot including a snug fitting shim to replace the removed material. In most cases, this modification was effective in curtailing the load-displacement trace when the propagating crack interacted with the slot on the backside of the specimen, without affecting the initial portion of the trace; this allowed crack propagation energies to be resolved. The propagation energy determined by this method is compared with the total energy and conventional test parameters. The crack propagation energy values inferred based on this should be validated, in future burst test.
Abstract
The ductile fracture toughness of steel is used to assess the ability of a pipeline to resist long running ductile fractures in a burst event. In modern low carbon clean steels [...]
- 0
- read
Characterizing Dynamic Crack-Resistance of Pipelines Using Laboratory-Scale Practices
B. Leis

Collection of open conferences in research transport (2000). Vol. 2000, 12

Abstract
The consequences of a dynamic fracture in a gas-transmission pipeline require that they be designed to avoid such incidents with great certainty. Because of the complexity of this fracture process, the only certain approach to determine fracture-arrest conditions involved full-scale experiments. As time passed empirically calibrated balance equations between the crack-driving conditions and the line-pipe steels crack-arrest capabilities were developed. Such models worked well until the introduction of high-toughness line pipe, for which to full-scale test predictions were non-conservative, and increasingly so as toughness increased. Problems with early CVN-based models led to development of alternative schemes."/jats:p" "jats:p"This paper presents results of experiments done to evaluate plausible alternatives to the CVN practice, which rely on an impact test identical to or adapted from the drop-weight tear-test (DWTT). As this practice is comparable to that of the CVN practice save for using an up-scale specimen geometry, results are presented and contrasted for these test methods, for pipe grades from B to X70, and toughness from less than 10 J in excess of 300 J. Data are analyzed to reveal trends not typically reported for such testing. It is shown that there is no essential difference between data developed from the CVN and DWTT practices, provided the results are compared at similar levels of impact-machine excess-energy capacity. Further, it is shown that non-conservative predictions of full-scale test behavior for higher-toughness steels can be traced to using the early CVN-based models at toughness levels well outside the range of their empirical calibration.
Abstract
The consequences of a dynamic fracture in a gas-transmission pipeline require that they be designed to avoid such incidents with great certainty. Because of the complexity [...]
- 0
- read
Integrating GIS and GPS Into Today’s Pipeline
D. Hobbs, K. Rummell

Collection of open conferences in research transport (2000). Vol. 2000, 11

Abstract
Today’s tools and technologies allow the pipeline industry to collect information and describe company pipeline assets in a productive way. Rooney Engineering, Inc. recently completed a 130-mile crude oil pipeline in the greater Los Angeles area of California with which wide ranges of technologies were utilized over an 8-year period. Review of all phases of this pipeline project offers a unique glimpse of managing and integrating traditional survey and Global Positioning System (GPS) techniques with a Geographic Information System (GIS). While the first portion of the project used traditional methods of photogrammetry and Computer Aided Drafting (CAD) to complete the conceptual design and construction drawings, the second portion utilized a combination of CAD, GIS and GPS technologies to assist the construction team during construction and as-built. Geographically organized data was later applied beyond the phases of pipeline construction; data was later used in one-call, contingency planning and emergency response."/jats:p" "jats:p"This paper will give an overview of the project, including pre-construction drawing preparation, construction zones, terrain types, political jurisdictions, and original staff assignments for data collection. The paper will discuss data dictionary design and management of collected field data, equipment and personnel requirements, and accuracy trade-off. The paper will examine the verification of data for attribute integrity and assignment of positional accuracy tags, along with specific methods of GPS and traditional data collection, while also exploring data management of incoming field data from multiple sources over an extensive timeline. Additionally, the paper will focus on the use of GIS to support construction monitoring and cost reconciliation analysis. Finally, we will review preparation of final drawings, summarize lessons learned, and discuss what the future offers in enhancing pipeline-mapping productivity.
Abstract
Today’s tools and technologies allow the pipeline industry to collect information and describe company pipeline assets in a productive way. Rooney Engineering, Inc. recently [...]
- 0
- read
A Stable and Fast Operating Door for Use With Pipelines and Launchers / Receivers of Various Diameters
A. Salim, A. Walker, J. Krogue, M. Perry

Collection of open conferences in research transport (2000). Vol. 2000, 10

Abstract
The oil and gas pipelines are spread around the world in all nations as complex networks. The increased usage of gas is rapidly increasing this network. These networks are generally made from various diameters of pipes. The pipelines are serviced on as required basis, using pig launcher and receivers to suit the pipe diameter. Pigs of different types may be launched in different sequences, to clean the pipes and to obtain various data related to pipe condition and location. The pig launching and receiving process uses rapid pressure changes in the launcher and receiver and some magnitude of impact may be experienced by the unit. This process also requires frequent access to the launcher/receiver unit. To have an efficient and cost effective usage of the launcher/receiver unit, it is essential to have a door mechanism, which is safe, robust, capable of the above loading conditions, requires minimum service and is easy to use. PECO has recently developed & designed a door, which incorporates ail the above requirements. The door was put to high pressure testing and the test results were so encouraging that PECO named it SafeLock® Closure. The design was developed with gas pipelines in mind. However it is equally applicable to vessels, exchangers and other metal openings where quick, frequent and easy access is required."/jats:p" "jats:p"Safety has been the prime concern through out the design and development process of this closure. Therefore the final product has resulted in a very safe closure."/jats:p" "jats:p"The initial design of the SafeLock® door / closure used a spring load to make it easy in operation. This was removed in the later design. The segmental blocks, usually called C-ring segments, are operated to move in and out of the shell-sub annulus. The closure opening and closing is performed by the use of a single lever arm. This way only one person can operate (open and close) the door / closure. For opening and closing, the lever-arm needs to be rotated less than 40 degree angle. The rotation direction of the lever arm in closing is reverse of that in opening. The door / head can be fully retrieved from the shell-sub and rest by the side of the launcher/receiver to provide complete access to the opening."/jats:p" "jats:p"This door / closure provides quick access to launcher / receiver, pig traps, meter provers, filter vessel, scrubber, scraper, manway to pressure vessel, etc. This closure can be mounted in the vertical or horizontal position. During change of filter elements, launching a pig, quick access to container under pressure, this closure door is designed to provide a safe and fast service."/jats:p" "jats:p"The construction, operation, design details and application of the new closure door are included in this paper and explained with the help of the design diagrams and photographs.
Abstract
The oil and gas pipelines are spread around the world in all nations as complex networks. The increased usage of gas is rapidly increasing this network. These networks are [...]
- 0
- read
Understanding the Physical Phenomena of Pipeline Decompression
R. Moore, G. King, X. Zhou

Collection of open conferences in research transport (2000). Vol. 2000, 9

Abstract
Pipeline decompression is an important aspect of risk assessment during the design and operation of high-pressure gas transmission pipelines. As numerical simulation technology improves, more sophisticated multiphase decompression flow models are emerging. A complete understanding of physical phenomena occurring during rapid pipeline decompression is essential in developing an accurate, advanced and fundamentally sound multiphase flow model."/jats:p" "jats:p"Pipeline decompression is a complex process that involves many thermodynamic and hydrodynamic non-equilibrium phenomena that govern the characteristics of fluid flow in the pipe. It is affected by parameters such as pipeline geometry, heat transfer, fluid characteristics, and various interactions between them."/jats:p" "jats:p"In this paper, we describe and discuss the pipeline decompression process, critical flow phenomena, fluid phase behavior, thermodynamic and hydrodynamic non-equilibria, characteristics of fluid mechanics, heat transfer and pipeline mechanics. Hopefully, this will enhance understandings of the predictive capabilities and limitations of various types of pipeline decompression models currently used for this process.
Abstract
Pipeline decompression is an important aspect of risk assessment during the design and operation of high-pressure gas transmission pipelines. As numerical simulation technology [...]
- 0
- read
A stochastic conflict detection model revisited
F. Bonnans, C. Martini, K. Blin, M. Akian, E. Hoffmanf, K. Zeghal, I. Rocquencourt

Collection of open conferences in research transport (2000). Vol. 2000, 8

Abstract
This paper addresses the theoretical issue of the uncertainty modelling to enhance conflict estimation for air traffic control. One of the important aspect is to identify and evaluate the impact on the positioning error of its different components: position, velocity, and acceleration error. To set up such a model, the major difficulty identified is to make explicit the dynamic of aircraft position that includes uncertainties. A possible enhancement of the classical probabilistic model of error by introducing a dynamic dimension to the position error model is proposed. This new position error model is generic and can thus be used for different probabilistic methods. Moreover, as shown in the paper, this new model can be tuned to reproduce the results used in reference and validated on real traffic.
Abstract
This paper addresses the theoretical issue of the uncertainty modelling to enhance conflict estimation for air traffic control. One of the important aspect is to identify [...]
- 0
- read
Minimizing Risk and Improving Operational Availability in the Pipeline Industry
P. Raynor

Collection of open conferences in research transport (2000). Vol. 2000, 7

Abstract
Risk is a function of the probability and consequence of an event that negatively impacts pipeline operations. These events may range from the shut-in of a compressor to a pipeline rupture. In order to quantify risk, it is important to have a thorough method of evaluating the probability and severity of the incident. Until recently, the methods used to assess risk have been mostly subjective and qualitative. Enhanced methods are now available that allow pipeline companies to gain a better understanding of the true risk and to realistically determine the availability and reliability of the pipeline. These methods facilitate balancing the cost of extra safeguards or protection layers with the actual risk of an event occurring, ultimately improving the financial success of a pipeline company.Copyright © 2000 by ASME
Abstract
Risk is a function of the probability and consequence of an event that negatively impacts pipeline operations. These events may range from the shut-in of a compressor to a [...]
- 0
- read
Volumes of expression: Artistic modelling and rendering of volume datasets
M. Jones, M. Chen, S. Treavett, R. Satherley

Collection of open conferences in research transport (2001). Vol. 2001, 3

Abstract
This paper presents the design and implementation of artistic effects in modelling and rendering of volume datasets. Following different stages of a volume-based graphics pipeline, we examine various properties of volume data, and illustrate how expressive and non-photorealistic effects can be implemented. We demonstrate that the true 3D nature of volume data makes it particularly applicable for this use, allowing the addition of complex effects at the modelling stage as well as during rendering.
Abstract
This paper presents the design and implementation of artistic effects in modelling and rendering of volume datasets. Following different stages of a volume-based graphics [...]
- 0
- read
A Computerized Analysis of ATC Tracking Data for an Operational Evaluation of CDTI/ADS-B Technology
S. Mills

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

Abstract
: In 1999, the Cargo Airlines Association and the Federal Aviation Administration conducted an operational evaluation (OpEval) of Cockpit Display of Traffic Information (CDTI) and Automatic Dependent Surveillance - Broadcast (ADS-B) technologies at the Airborne Express Airpark in Wilmington, Ohio. This evaluation was designed to demonstrate the benefits of CDTI, including safety, efficiency, and capacity. The evaluation included 13 aircraft of various types and their flight crews. The aircraft flew multiple flight patterns during the morning and the afternoon of a single day. Each traffic pattern flown by each aircraft was assigned to either the CDTI or baseline (no CDTI) condition. Human factors observers recorded data from the flight decks and the control tower. In addition, air traffic control (ATC) data were recorded by the participating ATC facilities. An important part of the analysis of such a demonstration is the examination of objective flight data. Because of the complexity of the OpEval, new computerized analysis techniques were developed and conducted. This paper describes those techniques in detail, as well as the results of the analysis. Methods such as those described here will be increasingly important as new technologies are developed and evaluated operationally.
Abstract
: In 1999, the Cargo Airlines Association and the Federal Aviation Administration conducted an operational evaluation (OpEval) of Cockpit Display of Traffic Information (CDTI) [...]
- 0
- read
An Emerging Methodology of Slope Hazard Assessment for Natural Gas Pipelines
M. Rizkalla, Z. Zhou, B. Liu, G. O’Neil

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

Abstract
TransCanada Pipelines Ltd. (TransCanada) operates approximately 37,000 km of natural gas gathering and transmission pipelines. Within the Alberta portion of this system there are almost 1100 locations where the pipeline(s) traverse slopes, primarily as the line approaches and exits stream crossings. In the past, the approach to managing the impact of slope movements on pipeline integrity has been reactive; site investigations and/or monitoring programs would only be initiated once the slope movements were sufficiently large so as to easily observe cracking or scarp development. In some cases these movements could lead to a pipeline rupture."/jats:p" "jats:p"To move to a proactive hazard management approach and to optimize the maintenance expenditure, TransCanada has developed a new slope assessment methodology. The objective of this methodology is to establish a risk-ranked list of slopes upon which maintenance decisions can be based. Using only internal and public information on site conditions as input to predictive models for rainfall-ground movement and pipe-soil interaction, a probability of pipeline failure can be generated for each slope. Estimates of risk using a consequence-matrix approach enabled the compilation of a risk-ranked list of hazardous slopes."/jats:p" "jats:p"This paper describes this methodology, and its implementation at TransCanada, and presents some of the results.
Abstract
TransCanada Pipelines Ltd. (TransCanada) operates approximately 37,000 km of natural gas gathering and transmission pipelines. Within the Alberta portion of this system there [...]
- 0
- read
A modularized approach for comprehensive air traffic system simulation
Y. Zhao, J. Robinson, J. Plaettner-Hochwarth

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

Abstract
This paper explains the design and computer implementation of a comprehensive dynamic air traffic system simulation program known as ComDATSS, currently under development at the University of Minnesota. ComDATSS simulates all essential components of an air traffic management system and their dynamic interactions. It provides a numerical testing environment for evaluating advanced ATM system designs and automation tools. Compared with existing ATM system simulation programs, ComDATSS employs an “as-it-is” physical modeling approach, generates four-dimensional aircraft trajectories, and allows for sufficient randomness in the simulations. In addition, the computer implementation of ComDATSS is implemented as a modular structure that can easily be modified and maintained.
Abstract
This paper explains the design and computer implementation of a comprehensive dynamic air traffic system simulation program known as ComDATSS, currently under development [...]
- 0
- read
Mechanical Factors Affecting Stress Corrosion Crack Growth Rates in Buried Pipelines
J. Beavers, A. Plumtree, S. Lambert, R. Sutherby, B. Delanty

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

Abstract
Over the past several years, investigations have been carried out into the rate of crack growth in pipeline steels in simulated, near-neutral pH, groundwater environment (NS4 solution). Pre-cracked specimens were subject to constant amplitude loading under various frequencies, maximum loads and R-ratios (minimum/maximum load). Test times varied from about 20 to 400 days. Transgranular crack features, similar to those found in service, have been observed. The extent of crack growth was monitored using either electrical potential drop or detailed metallographic examinations at two laboratories. The resulting crack growth rates from both labs are consistent with a superposition model based on a summation of fatigue (Paris Law) and static (SCC) crack growth rates. Differences between the results at the two laboratories are discussed.
Abstract
Over the past several years, investigations have been carried out into the rate of crack growth in pipeline steels in simulated, near-neutral pH, groundwater environment (NS4 [...]
- 0
- read
Flight Data Processing Techniques to Identify Unusual Events
I. Mugtussids

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

Abstract
Modern aircraft are capable of recording hundreds of parameters during flight. This fact not only facilitates the investigation of an accident or a serious incident, but also provides the opportunity to use the recorded data to predict future aircraft behavior. It is believed that, by analyzing the recorded data, one can identify precursors to hazardous behavior and develop procedures to mitigate the problems before they actually occur. Because of the enormous amount of data collected during each flight, it becomes necessary to identify the segments of data that contain useful information. The objective is to distinguish between typical data points, that are present in the majority of flights, and unusual data points that can be only found in a few flights. The distinction between typical and unusual data points is achieved by using classification procedures. In this dissertation, the application of classification procedures to flight data is investigated. It is proposed to use a Bayesian classifier that tries to identify the flight from which a particular data point came. If the flight from which the data point came is identified with a high level of confidence, then the conclusion that the data point is unusual within the investigated flights can be made. The Bayesian classifier uses the overall and conditional probability density functions together with a priori probabilities to make a decision. Estimating probability density functions is a difficult task in multiple dimensions. Because many of the recorded signals (features) are redundant or highly correlated or are very similar in every flight, feature selection techniques are applied to identify those signals that contain the most discriminatory power. In the limited amount of data available to this research, twenty five features were identified as the set exhibiting the best discriminatory power. Additionally, the number of signals is reduced by applying feature generation techniques to similar signals. To make the approach applicable in practice, when many flights are considered, a very efficient and fast sequential data clustering algorithm is proposed. The order in which the samples are presented to the algorithm is fixed according to the probability density function value. Accuracy and reduction level are controlled using two scalar parameters: a distance threshold value and a maximum compactness factor. Ph. D.
Abstract
Modern aircraft are capable of recording hundreds of parameters during flight. This fact not only facilitates the investigation of an accident or a serious incident, but [...]
- 1
- read
Development of Optimization and Simulation Models for the Analysis of Airfield Operations
H. Baik

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

Abstract
This research is concerned with the modeling and development of algorithmic approaches for solving airport operational problems that arise in Air Traffic Control (ATC) systems within the terminal area at hub airports. Specifically, the problems addressed include the Aircraft Sequencing Problem (ASP) for runway operations, the Network Assignment Problem (NAP) for taxiway operations, and a simulation model for the evaluation of current or proposed ATC system in detail. For the ASP, we develop a mathematical model and apply the Reformulation-Linearization-Technique (RLT) of Sherali and Adams to construct an enhanced tightened version of the proposed model. Since ASP is NP-Hard and in fact, it is a variation of the well-known Traveling Salesman Problem with time-windows, sub-optimal solutions are usually derived to accommodate the real-time constraints of ATC systems. Nevertheless, we exhibit a significant advancement in this challenging class of problem. Also for the purpose of solving relatively large sized problems in practice, we develop and test suitable heuristic procedures. For the NAP, we propose a quasi-dynamic assignment scheme which is based on the incremental assignment technique. This quasi-dynamic assignment method assumes that the current aircraft route is influenced only by the previous aircraft assigned to the network. This simplified assumption obviates the need for iterative rerouting procedures to reach a pure equilibrium state which might not be achievable in practical taxiway operations. To evaluate the overall system, we develop a microscopic simulation model. The simulation model is designed to have the capability for reproducing not only the dynamic behavior of aircraft, but also incorporates communication activities between controllers and pilots. These activities are critical in ATC operations, and in some instances, might limit the capacity of the facility. Finally, using the developed simulation model named Virginia Tech Airport Simulation Model (VTASM) in concert with ASP and NAP, we compare the overall efficiencies of several control strategies, including that of the existing control system as well as of the proposed advanced control system. Ph. D.
Abstract
This research is concerned with the modeling and development of algorithmic approaches for solving airport operational problems that arise in Air Traffic Control (ATC) systems [...]
- 0
- read
Trafikte Tıkanıklık:Talep Ve Arz Yönetimi
H. Demir

Collection of open thesis in transport research (2001). Vol. 2001, 2

Abstract
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2001
- 4
- read
Landfill Gas Conversion to LNG and LCO{sub 2}. Final Report
W. Cook, W. Brown, L. Siwajek

Collection of open reports in transport research (2000). Vol. 2000, 23

Abstract
This report summarizes work on the development of a process to produce LNG (liquefied methane) for heavy vehicle use from landfill gas (LFG) using Acrion's CO{sub 2} wash process for contaminant removal and CO{sub 2} recovery. Work was done in the following areas: (1) production of natural gas pipeline methane for liquefaction at an existing LNG facility, (2) production of LNG from sewage digester gas, (3) the use of mixed refrigerants for process cooling in the production of LNG, liquid CO{sub 2} and pipeline methane, (4) cost estimates for an LNG production facility at the Arden Landfill in Washington PA.
Abstract
This report summarizes work on the development of a process to produce LNG (liquefied methane) for heavy vehicle use from landfill gas (LFG) using Acrion's CO{sub 2} wash [...]
- 2
- read
Conceptual design assessment for the co-firing of bio-refinery supplied lignin project. Quarterly report, July 1--September 30, 2000
J. Ranney, T. Berglund, C. Babb

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

Abstract
The initial design criteria of the MSW to ethanol facility have been completed along with preliminary site identification and layouts for the processing facility. These items are the first step in evaluating the feasibility of this co-located facility. Pilot facility design and modification are underway for the production and dewatering of the lignin fuel. Major process equipment identification has been completed and several key unit operations will be accomplished on rental equipment. Equipment not available for rental or at TVA has been ordered and facility modification and shakedown will begin in October. The study of the interface and resulting impacts on the TVA Colbert facility are underway. The TVA Colbert fossil plant is fully capable of providing a reliable steam supply for the proposed Masada waste processing facility. The preferred supply location in the Colbert steam cycle has been identified as have possible steam pipeline routes to the Colbert boundary. Additional analysis is underway to fully predict the impact of the steam supply on Colbert plant performance and to select a final steam pipeline route.
Abstract
The initial design criteria of the MSW to ethanol facility have been completed along with preliminary site identification and layouts for the processing facility. These items [...]
- 0
- read
Value pricing on the I-15 freeway
D. Van Amelsfort, D. Lindveld, P. Bovy

Collection of open reports in transport research (2000). Vol. 2000, 18

Abstract
In San Diego, California, a value pricing project has been implemented in order to make better use of the existing reversible HOV-facility on Interstate 15, just north of San Diego. In this project, paying solo drivers are allowed to use the Express Lanes. These drivers experience the benefits of free-flow travel instead of the heavily congested traffic situations on the main lanes. The price for using the Express Lanes is determined dynamically and depends on the flow of traffic on these lanes. The objectives of the research presented in the report are: (1) to determine if the project has a congestion relieving effect for the main lanes, (2) how travelers decide between the different travel options in the 1-15 corridor. Using the available historical traffic data, changes in traffic conditions on the 1-15 main lanes were examined. The project does not seem to have a congestion relieving effect. The number of participant is small and there is almost always latent demand. In order to determine how people choose between the different travel options, travel time savings for the Express Lane users were determined. The travel time savings were calculated from loop detector speed at different cross-sections and reach values up to 18 minutes. The estimated travel time savings were then used to estimate mode choice models which explain the choice behavior of travelers between spending time by traveling on the main lanes and spending money by traveling on the Express Lanes. The choice models show that wealthier people, people with a higher level of education, home owners, and woman are more likely to pay for the use of the Express Lanes. The value-of-time of program participants is approximately $31.00 per hour for commuters and $71.00 per hour for non-commuters.
Abstract
In San Diego, California, a value pricing project has been implemented in order to make better use of the existing reversible HOV-facility on Interstate 15, just north of [...]
- 1
- read
Value pricing on the I-15 freeway: Willingness to pay for improved travel service
D. Van Amelsfort, D. Lindveld, P. Bovy

Collection of open reports in transport research (2000). Vol. 2000, 17

Abstract
In San Diego, California, a value pricing project has been implemented in order to make better use of the existing reversible HOV-facility on Interstate 15, just north of San Diego. In this project, paying solo drivers are allowed to use the Express Lanes. These drivers experience the benefits of free-flow travel instead of the heavily congested traffic situations on the main lanes. The price for using the Express Lanes is determined dynamically and depends on the flow of traffic on these lanes. The objectives of the research presented in the report are: (1) to determine if the project has a congestion relieving effect for the main lanes, (2) how travelers decide between the different travel options in the 1-15 corridor. Using the available historical traffic data, changes in traffic conditions on the 1-15 main lanes were examined. The project does not seem to have a congestion relieving effect. The number of participant is small and there is almost always latent demand. In order to determine how people choose between the different travel options, travel time savings for the Express Lane users were determined. The travel time savings were calculated from loop detector speed at different cross-sections and reach values up to 18 minutes. The estimated travel time savings were then used to estimate mode choice models which explain the choice behavior of travelers between spending time by traveling on the main lanes and spending money by traveling on the Express Lanes. The choice models show that wealthier people, people with a higher level of education, home owners, and woman are more likely to pay for the use of the Express Lanes. The value-of-time of program participants is approximately $31.00 per hour for commuters and $71.00 per hour for non-commuters.
Abstract
In San Diego, California, a value pricing project has been implemented in order to make better use of the existing reversible HOV-facility on Interstate 15, just north of [...]
- 0
- read
Qualification of Three On-line Slurry Monitoring Devices for Application during Waste Retrieval Operations at DOE Sites
T. May, J. Bontha, J. Bamberger, T. Hylton

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

Abstract
Millions of gallons of radioactive liquid and sludge wastes must be retrieved from underground storage tanks at the U.S. Department of Energy sites to be staged and transferred to treatment facilities and processed into final waste forms. Retrieval operations involve mixing solid and liquid wastes to create slurries that can be transported via underground pipelines to specified locations for treatment or disposal. A major concern during the transfer operations is plugging of the transfer lines. Blocked transfer lines could significantly escalate the remediation costs both in terms of pipeline replacement costs and costs of maintenance of inactive facilities and operating personnel.
Abstract
Millions of gallons of radioactive liquid and sludge wastes must be retrieved from underground storage tanks at the U.S. Department of Energy sites to be staged and transferred [...]
- 0
- read
An Evaluation of a Dual Coriolis Meter System for In-Line Monitoring of Suspended Solids Concentrations in Radioactive Slurries
T. Hylton

Collection of open reports in transport research (2000). Vol. 2000, 14

Abstract
The U.S. Department of Energy (DOE) has millions of gallons of radioactive liquid and sludge wastes stored in underground tanks at several of its sites. In order to comply with various regulations and to circumvent potential problems associated with tank integrity, these wastes must be retrieved from the tanks, transferred to treatment facilities (or other storage locations), and processed to stable waste forms. The sludge wastes will typically be mobilized by some mechanical means (e.g., mixer pump, submerged jet) and mixed with the respective supernatants to create slurries that can be transferred by pipeline to the desired destination. Depending on the DOE site, these slurries may be transferred up to six miles. Since the wastes are radioactive, it is critically important for the transfers to be made without plugging a pipeline. To reduce such a risk, the relevant properties of the slurry (e.g., density, suspended solids concentration, viscosity, and particle size distribution) should be determined to be within acceptable limits prior to transfer. These properties should also be continuously monitored and controlled within specified limits while the transfer is in progress. The baseline method for determining the transport properties of slurries involves sampling and analysis; however, this method is time-consuming, and costly, and it does not provide real-time information. In addition, personnel who collect and analyze the samples are exposed to radiation. It is also questionable as to whether a laboratory analyst can obtain representative aliquots from the sample jar for these solid-liquid mixtures. The alternative method for determining the transport properties is in-line analysis. An in-line instrument is one that is connected to the process, analyzes the slurry as it flows through or by the instrument, and provides the results within seconds. This instrument can provide immediate feedback to operators so that, when necessary, the operators can respond quickly to counteract conditions that could lead to pipeline pluggage (e.g., backflushing the pipeline with water). One of the highest priorities is to determine the concentration of suspended solids in each of the slurries. In the project described in this report, two Coriolis meters were used simultaneously to create a suspended solids monitoring system that would provide accurate results with high precision. One Coriolis meter was used to measure the density of the slurry, while the other meter was used to measure the density of the carrier fluid (i.e., after filtration to remove the solid particles). The suspended solids concentration was then calculated from the density relationships between the slurry, the carrier fluid, and the dry solid particles. The latter density was determined by laboratory analysis and was assumed to be constant throughout the periods that grab samples were collected.
Abstract
The U.S. Department of Energy (DOE) has millions of gallons of radioactive liquid and sludge wastes stored in underground tanks at several of its sites. In order to comply [...]
- 0
- read
How large is the gap between present and efficient transport prices in Europe?
S. Proost, K. Van Dender, C. Courcelle, B. De Borger, J. Peirson, R. Vickerman, E. Gibbons, O. O&apos, Q. Heaney, J. Van den Bergh, E. Verhoef

Collection of open reports in transport research (2001). Vol. 2001, 5

Abstract
In this paper we analyse the gap between present transport prices and efficient transport prices. Efficient transport prices are those prices that maximise economic welfare, including external costs (congestion, air pollution, accidents). The methodology is applied to six urban and interregional case studies using one common optimal pricing model. The case studies cover passenger as well as freight transport and cover all modes. We find that prices need to be raised most for peak urban passenger car transport and to a lesser extent for interregional road transport. Optimal pricing results for public transport are more mixed. We show that current external costs on congested roads are a bad guide for optimal taxes and tolls: the optimal toll that takes into account the reaction of demand is often less than one third of the present marginal external cost. ispartof: Working Papers pages:1-29 status: published
Abstract
In this paper we analyse the gap between present transport prices and efficient transport prices. Efficient transport prices are those prices that maximise economic welfare, [...]
- 0
- read
Interface Control Document Between the Double Shell Tank (DST) system and the Waste Encapsulation and Storage Facility (WESF)
G. Hofferber

Collection of open reports in transport research (2000). Vol. 2000, 13

Abstract
This Interface Control Document (ICD) describes interfaces between the Double-Shell Tanks (DST) System and Waste Encapsulation and Storage Facility (WESF) (figure 1). WESF is currently operational as a storage facility for cesium and strontium capsules. This ICD covers current operational interfaces and those envisioned during Terminal Clean Out (TCO) activities in the future. WESF and the DST System do not have a direct physical interface. 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 (RPP) DST System and systems/facilities operated by organizations or 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 interfaces between the Double-Shell Tanks (DST) System and Waste Encapsulation and Storage Facility (WESF) (figure 1). WESF [...]
- 0
- read
An Agent-Inspired Active Network Resource Trading Model Applied to Congestion Control
G. Leduc, L. Yamamoto

Collection of open chapters of books in transport research (2000). Vol. 2000, 23

Abstract
In order to accommodate fluctuations in network conditions, adaptive applications need to obtain information about resource availability, Using active networks, new models for adaptive applications can be envisaged, which can benefit from the possibility to send mobile code to the network nodes. We describe a model for trading resources inside an active net-work node, based on the interaction between capsules as reactive user agents, and resource manager agents which reside in the network nodes. We apply the model to the case of a many-to-one audio application with congestion control, which trades off link resources against memory when there is congestion at the outgoing interface towards the destination. Our simulation results indicate that the application makes effective use of the available resources, and it also allows resources to be shared according to user preferences. Peer reviewed
Abstract
In order to accommodate fluctuations in network conditions, adaptive applications need to obtain information about resource availability, Using active networks, new models [...]
- 0
- read
Transport and environment: from policy measures to sustainability notions and back
E. Verhoef, E. Feitelson

Collection of open chapters of books in transport research (2001). Vol. 2001, 25

Abstract
The impact of transport on the environment is a major issue of worldwide concern. This important new book presents state-of-the-art contributions on spatial and technological aspects of transport in relation to environmental degradation, together with analysis of sustainable transport policy.
Abstract
The impact of transport on the environment is a major issue of worldwide concern. This important new book presents state-of-the-art contributions on spatial and technological [...]
- 0
- read
Employer-Paid parking: A Nationwide Survey of Employers' Parking Subsidy Policies
D. Shoup, M. Breinholt

Collection of open chapters of books in transport research (2001). Vol. 2001, 24

Abstract
Ninety-five percent of automobile commuters in the United States park free at work. To deal with the traffic congestion and air pollution caused by parking subsidies, California law now requires many employers to offer employees the option to cash out their parking subsidies. Similar Federal legislation has been proposed. This nationwide survey found that employers in the United States off employees 84.8 million free parking spaces. Employers own 65.3 million of these free parking spaces, and rent the other 19.5 million. Employers of fewer than twenty employees provide more than half of all employer-paid parking spaces.
Abstract
Ninety-five percent of automobile commuters in the United States park free at work. To deal with the traffic congestion and air pollution caused by parking subsidies, California [...]
- 1
- read
International transport and the environment: an assessment of trends and driving forces
P. Nijkamp, D. Veen-Groot

Collection of open chapters of books in transport research (2001). Vol. 2001, 23

Abstract
The impact of transport on the environment is a major issue of worldwide concern. This important new book presents state-of-the-art contributions on spatial and technological aspects of transport in relation to environmental degradation, together with analysis of sustainable transport policy.
Abstract
The impact of transport on the environment is a major issue of worldwide concern. This important new book presents state-of-the-art contributions on spatial and technological [...]
- 0
- read
Radioactive air emission notice of construction noc for construction of liquid effluent transfer system project w 519
N. HOMAN

Collection of open reports in transport research (2000). Vol. 2000, 12

Abstract
The proposed action is to install a new liquid effluent transfer system (three underground waste transfer pipelines). As such, a potential new source will be created as a result of the construction activities. The anticipated emissions associated with this activity are insignificant. Document type: Report
Abstract
The proposed action is to install a new liquid effluent transfer system (three underground waste transfer pipelines). As such, a potential new source will be created as a [...]
- 0
- read
Field demonstration of a membrane process to recover heavy hydrocarbons and to remove water from natural gas annual report 1999
N. Jacobs, C. Bailey, N. Lokhandwala, J. Kaschemekat, N. Hofmann, R. Baker, M. Jacobs, K. Lokhandwala, N. Baker, T. Hofmann, N. Kaschemekat, N. Bailey, N. Group

Collection of open reports in transport research (2000). Vol. 2000, 11

Abstract
The objective of this project is to design, construct and field demonstrate a 3-MMscfd membrane system to recover natural gas liquids (NGL) and remove water from raw natural gas. An extended field test to demonstrate system performance under real-world conditions is required to convince industry users of the efficiency and reliability of the process. The system will be designed and fabricated by Membrane Technology and Research, Inc. (MTR) and then installed and operated at British Petroleum (BP)-Amoco's Pascagoula, MS plant. The Gas Research Institute will partially support the field demonstration and BP-Amoco will help install the unit and provide onsite operators and utilities. The gas processed by the membrane system will meet pipeline specifications for dewpoint and Btu value and can be delivered without further treatment to the pipeline. Based on data from prior membrane module tests, the process is likely to be significantly less expensive than glycol dehydration followed by propane refrigeration, the principal competitive technology. At the end of this demonstration project the process will be ready for commercialization. The route to commercialization will be developed during this project and may involve collaboration with other companies already servicing the natural gas processing industry. Document type: Report
Abstract
The objective of this project is to design, construct and field demonstrate a 3-MMscfd membrane system to recover natural gas liquids (NGL) and remove water from raw natural [...]
- 0
- read
Evaluation of hose in hose transfer line service life for hanford s interim stabilization program
T. Torres, T. TORRES

Collection of open reports in transport research (2000). Vol. 2000, 10

Abstract
RPP-6153, Engineering Task Plan for Hose-in-Hose Transfer System for the Interim Stabilization Program, defines the programmatic goals, functional requirements, and technical criteria for the development and subsequent installation of transfer line equipment to support Hanford's Interim Stabilization Program. RPP-6028, Specification for Hose in Hose Transfer Lines for Hanford's Interim Stabilization Program, has been issued to define the specific requirements for the design, manufacture, and verification of transfer line assemblies for specific waste transfer applications. Included in RPP-6028 are tables defining the chemical constituents of concern to which transfer lines will be exposed. Current Interim Stabilization Program planning forecasts that the at-grade transfer lines will be required to convey pumpable waste for as much as three years after commissioning. Prudent engineering dictates that the equipment placed in service have a working life in excess of this forecasted time period, with some margin to allow for future adjustments to the planned schedule. This document evaluates the effective service life of the Hose-in-Hose Transfer Lines, based on information submitted by the manufacturer and published literature. The effective service life of transfer line assemblies is a function of several factors. Foremost among these are process fluid characteristics, ambient environmental conditions, and the manufacturer's stated shelf life. This evaluation examines the manufacturer's certification of shelf life, the manufacturer's certifications of chemical compatibility with waste, and published literature on the effects of exposure to ionizing radiation on the mechanical properties of elastomeric materials to evaluate transfer line service life. Document type: Report
Abstract
RPP-6153, Engineering Task Plan for Hose-in-Hose Transfer System for the Interim Stabilization Program, defines the programmatic goals, functional requirements, and technical [...]
- 1
- read
Evaluation of 3 inch sn 219 failure and s and sx tank farm saltwell piping
J. ELSEN

Collection of open reports in transport research (2000). Vol. 2000, 9

Abstract
Evaluation of direct buried piping currently in use or designated for future Saltwell pumping in S and SX Farms. Documented evaluation of failed S-103 saltwell pumping transfer line 3 inch SN-219. This evaluation is intended to reflect current status of Saltwell piping, when taken in context with referenced documents. Document type: Report
Abstract
Evaluation of direct buried piping currently in use or designated for future Saltwell pumping in S and SX Farms. Documented evaluation of failed S-103 saltwell pumping transfer [...]
- 0
- read
Waste feed delivery transfer system analysis
L. JULYK

Collection of open reports in transport research (2000). Vol. 2000, 8

Abstract
This document provides a documented basis for the required design pressure rating and pump pressure capacity of the Hanford Site waste-transfer system in support of the waste feed delivery to the privatization contractor for vitrification. The scope of the analysis includes the 200 East Area double-shell tank waste transfer pipeline system and the associated transfer system pumps for a11 Phase 1B and Phase 2 waste transfers from AN, AP, AW, AY, and A2 Tank Farms. Document type: Report
Abstract
This document provides a documented basis for the required design pressure rating and pump pressure capacity of the Hanford Site waste-transfer system in support of the waste [...]
- 1
- read
Determination of Secondary Encasement Pipe Design Pressure
A. TEDESCHI

Collection of open reports in transport research (2000). Vol. 2000, 7

Abstract
This document published results of iterative calculations for maximum tank farm transfer secondary pipe (encasement) pressure upon failure of the primary pipe. The maximum pressure was calculated from a primary pipe guillotine break. Results show encasement pipeline design or testing pressures can be significantly lower than primary pipe pressure criteria. Document type: Report
Abstract
This document published results of iterative calculations for maximum tank farm transfer secondary pipe (encasement) pressure upon failure of the primary pipe. The maximum [...]
- 0
- read
Upgrading natural gas via membrane separation processes
P. Rice, N. Rice, J. Hao, S. S.A.Stern, N. S.A.Stern, N. Hao

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

Abstract
The objective of the present study is to assess the potential usefulness of membrane separation processes for removing CO{sub 2} and H{sub 2}S from low-quality natural gas containing substantial amounts of both these ''acid'' gases, e.g., up to 40 mole-% CO{sub 2} and 10 mole-% H{sub 2}S. The membrane processes must be capable of upgrading the crude natural gas to pipeline specifications ({le} 2 mole-% CO{sub 2}, {le} 4 ppm H{sub 2}S). Moreover, these processes must also be economically competitive with the conventional separation techniques, such as gas absorption, utilized for this purpose by the gas industry. Document type: Report
Abstract
The objective of the present study is to assess the potential usefulness of membrane separation processes for removing CO{sub 2} and H{sub 2}S from low-quality natural gas [...]
- 1
- read
Qualification of three on line slurry monitoring devices for application during waste retrieval operations at doe sites
N. Bontha, N. Hylton, N. May

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

Abstract
Millions of gallons of radioactive liquid and sludge wastes must be retrieved from underground storage tanks at the U.S. Department of Energy sites to be staged and transferred to treatment facilities and processed into final waste forms. Retrieval operations involve mixing solid and liquid wastes to create slurries that can be transported via underground pipelines to specified locations for treatment or disposal. A major concern during the transfer operations is plugging of the transfer lines. Blocked transfer lines could significantly escalate the remediation costs both in terms of pipeline replacement costs and costs of maintenance of inactive facilities and operating personnel. Document type: Report
Abstract
Millions of gallons of radioactive liquid and sludge wastes must be retrieved from underground storage tanks at the U.S. Department of Energy sites to be staged and transferred [...]
- 0
- read
Project Development Specification for Special Protective Coating
D. MCGREW

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

Abstract
Establishes the performance, design development, and test requirements for the Special Protective Coating. The system engineering approach was used to develop this document in accordance with the guidelines laid out in the Systems Engineering Management Plan for Project W-314. Document type: Report
Abstract
Establishes the performance, design development, and test requirements for the Special Protective Coating. The system engineering approach was used to develop this document [...]
- 0
- read
Technical evaluation for the determination of cgi designation for safety class items incorporated in hose in hose transfer line assemblies
J. BUCHANAN

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

Abstract
The purpose of this technical evaluation is to determine whether the secondary hoses are to be categorized as Commercial Grade Items (CGI) or Engineered Equipment. This determination will identify whether or not use of the CGI Dedication process is appropriate. Document type: Report
Abstract
The purpose of this technical evaluation is to determine whether the secondary hoses are to be categorized as Commercial Grade Items (CGI) or Engineered Equipment. This determination [...]
- 1
- read
The vicious circles of control regional governments and insiders in privatized russian enterprises
R. Desai, I. Goldberg

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

Abstract
How can one account for the puzzling behavior of insider-managers who, in stripping assets from the very firms they own, appear to be stealing from one pocket to fill the other? The authors suggest that such asset-stripping and failure to restructure are the consequences of interactions between insiders (manager-owners) and regional governments in a particular property rights regime. In this regime, the ability to realize value is limited by uncertainty and illiquidity, so managers have little incentive to increase value. As the central institutions that rule Russia have ceded their powers to the regions, regional governments have imposed various distortions on enterprises to protect local employment. Prospective outsider-investors doubt they can acquire the control rights they need for restructuring firms and doubt they can avoid the distortions regional governments impose on the firms in which they might invest. The result: little restructuring and little new investment. And regional governments, knowing the firms' taxable cash flows will have been reduced through cash flow diversion, have responded by collecting revenues in kind. To disentangle these vicious circles of control, the authors propose a pilot for transforming ownership in insider-dominated firms through a system of simultaneous tax-debt-for-equity conversion and resale through competitive auctions. The objective: to show regional governments, for example, that a more sustainable way to protect employment is to give managers incentives to increase enterprises' value by transferring effective control to investors. The proposed mechanism would provide cash benefits to insiders who agree to sell control to outside investors. The increased cash revenue (rather than in-kind or money surrogates) would enable regional governments to finance safety nets for the unemployed and to promote other regional initiatives. Document type: Book
Abstract
How can one account for the puzzling behavior of insider-managers who, in stripping assets from the very firms they own, appear to be stealing from one pocket to fill the [...]
- 0
- read
Give growth and macroeconomic stability in russia a chance harden budgets by eliminating nonpayments
B. Pinto, V. Drebentsov, A. Morozov

Collection of open chapters of books in transport research (2000). Vol. 2000, 20

Abstract
The authors analyze the links between Russias disappointing growth performance in the second half of the 1990s, its costly and unsuccessful stabilization, the macroeconomic meltdown of 1998, and the spectacular rise of non-payments. Non-payments flourished in an environment of fundamental inconsistency between a macroeconomic policy geared at sharp disinflation, and a microeconomic policy of bailing enterprises out through soft budget constraints. Heavy untargeted implicit subsidies flowing through the non-payments system (amounting to 10 percent of GDP annually) have stifled growth, contributed to the August 1998 meltdown, through their impact on public debt, and have made at best a questionable contribution to equity. Dismantling this system must be a top priority, along with promoting enterprise restructuring and growth (by hardening budget constraints) and medium-term macroeconomic stability (by reducing the size of subsidies). Getting the government out of the non-payments system means settling all appropriately controlled budgetary expenditures on time, and in cash, and eschewing spending arrears, thereby setting an example for enterprises, and laying the groundwork for eliminating tax offsets at all levels of government, and insisting on cash tax payments. To stop energy-related subsidies, would require not only that the government pay its own energy bills on time, and in cash, but also that the energy monopolies be empowered to disconnect non-paying clients. This will enable the government to insist that the energy monopolies in turn pay their own taxes in full, and on time. Document type: Book
Abstract
The authors analyze the links between Russias disappointing growth performance in the second half of the 1990s, its costly and unsuccessful stabilization, the macroeconomic [...]
- 0
- read
Workplace studies where the rubber hits the road notes on the deployment problem in workplace studies
B. Anderson, B. Anderson

Collection of open chapters of books in transport research (2000). Vol. 2000, 18

Abstract
Document type: Part of book or chapter of book
- 0
- read
OnLine - not on the Leash: neue Formen mobilen informatisierten Arbeitens aus soziologischer Perspektive
S. Pfeiffer

Collection of open chapters of books in transport research (2001). Vol. 2001, 14

Abstract
"Der populäre Schrei nach mobilen, flexiblen Arbeitskräften bestimmt den öffentlichen Diskurs seit Jahren. In den 80ern, als die Dauerhaftigkeit großer Arbeitslosenzahlen nicht mehr zu leugnen war, galt individualisierte Mobilität als wie sich zeigte nicht sehr erfolgreiches Allheilmittel zur Bekämpfung der Arbeitslosigkeit. In den 90er Jahren entwickelte sich der Begriff Mobilität im Rahmen der Debatten rund um Globalisierung und Informationsgesellschaft zum Synonym für einen zeitgemäßen Arbeits- und Lebensstil. Alles scheint mobil zu werden: die Technik, die Kapitalflüsse, die sozialen Beziehungen und nicht zuletzt die Arbeit. Öffentliche Debatten neigen naturgemäß zur Polarisierung; Keywords dieser Debatten werden zu gerne einseitig positiv oder negativ aufgeladen, um die jeweilige Weltsicht argumentativ zu untermauern. Dabei gerät die Komplexität Widersprüchlichkeit und Gegenläufigkeit die sozialem und gesellschaftlichem Wandel immanent anhaftet, oft genug aus dem Blick." (Autorenreferat) Document type: Part of book or chapter of book
Abstract
"Der populäre Schrei nach mobilen, flexiblen Arbeitskräften bestimmt den öffentlichen Diskurs seit Jahren. In den 80ern, als die Dauerhaftigkeit großer Arbeitslosenzahlen [...]
- 2
- read
Forecasting the demand for privatized transport what economic regulators should know and why
A. Estache, L. Trujillo, E. Quinet

Collection of open chapters of books in transport research (2000). Vol. 2000, 14

Abstract
Forecasting has long been a challenge, and will remain so for the foreseeable future. But the analytical instruments and data processing capabilities available through the latest technology, and software, should allow much better forecasting than transport ministries, or regulatory agencies typically observe. Privatization brings new needs for demand forecasting. More attention is paid to risk under privatization, than when investments are publicly financed. And regulators must be able to judge traffic studies done by operators, and to learn what strategic behavior influenced these studies. Many governments, and regulators avoid good demand, modeling out of lack of conviction that theory, and models can do better than the"old hands"of the sector. This is dangerous when privatization changes the nature of business. For projects amounting to investments of $ 100-200 million, a cost of $ 100,000-200,000 is not a reason to reject a reasonable modeling effort. And some private forecasting firms are willing to sell guarantees, or insurance with their forecasts, to cover significant gaps between forecasts, and reality. Document type: Book
Abstract
Forecasting has long been a challenge, and will remain so for the foreseeable future. But the analytical instruments and data processing capabilities available through the [...]
- 1
- read
Integrating Model Checking and HCI Tools to Help Designers Verify User Interface Properties
F. Paterno, C. Santoro, P. Palaque

Collection of open chapters of books in transport research (2001). Vol. 2001, 10

Abstract
In this paper we present a method that aims to integrate the use of formal techniques in the design process of interactive applications, with particular attention to those applications where both usability and safety are main concerns. The method is supported by a set of tools. We will also discuss how the resulting environment can be helpful in reasoning about multi-user interactions using the task model of an interactive application. Examples are provided from a case study in the field of air traffic control. Document type: Part of book or chapter of book
Abstract
In this paper we present a method that aims to integrate the use of formal techniques in the design process of interactive applications, with particular attention to those [...]
- 1
- read
A Tool Suite for Integrating Task and System Models through Scenarios
F. Paternò, C. Santoro, R. Bastide, D. Navarre, P. Palanque

Collection of open chapters of books in transport research (2001). Vol. 2001, 8

Abstract
This paper presents a set of tools supporting the development of interactive systems using two different notations. One of these notations, called ConcurTaskTrees (CTT), is used for task modelling. The other notation, called Interactive Cooperative Objects (ICO), is used for system modelling. Even though these two kinds of models represent two different views of the same world (users interacting with interactive systems), they are built by different people and used independently. The aim of this paper is to propose the use of scenarios as a bridge between these two views. On the task modelling side, scenarios are seen as possible traces of activities, while on the system side, they are viewed as traces of actions. This generic approach is presented in a case study in the domain of Air Traffic Control. Document type: Part of book or chapter of book
Abstract
This paper presents a set of tools supporting the development of interactive systems using two different notations. One of these notations, called ConcurTaskTrees (CTT), is [...]
- 1
- read
Broad Roads in a Thin Country: Infrastructure Concessions in Chile
S. Hinojosa, A. Gomez-Lobo

Collection of open chapters of books in transport research (2000). Vol. 2000, 7

Abstract
To increase investment in infrastructure, in the early 1990s Chiles government introduced private capital into the transport infrastructure sector, covering roads and highways, bridges, tunnels, and airports. The chosen mechanism: a concession scheme through which private firms would finance and build a given project and then operate the infrastructure for a set of number of years, recovering their investment by collecting tolls from users. Among the lessons learned from the experience: 1) As much as possible, avoid concessioning roads for which there are convenient alternative freeways nearby. 2) Choose the right variable for awarding a concession. Avoid mechanisms that (by promoting large payments to the state or short-term concession periods) encourage high tolls, and if you choose to award a concession to the firm charging the lowest tolls, place a floor and ceiling on possible bids. The floor is to guarantee the concessions financial viability; the ceiling is to prevent inefficient traffic diversions. Ties at either end should be resolved by a second variable, such as the level of transfers between the state and the firm. 3) Allow downward toll flexibility so that the concessionaire can react to unexpectedly low traffic flows, especially for certain types of vehicles. 4) Pay special attention to the tendering mechanism and to the general incentive structure. There are limits to the pure least-present-value-of-revenue (LPVR) auction, but income guarantees do enhance liquidity. In fact, a minimum-income guarantee through an LPVR auction is an instrument for credit enhancement, not income support. Alternatively, some form of financial innovation should be encouraged to make debt service commitments more flexible. 5) If concessions are tendered by traditional methods and income guarantees will be given, cover only a fraction of the concessionaires expected income stream, to reduce the states financial exposure and to improve the incentives to the concessionaire. 6) Make the contracts as complete as possible but allow for later modifications or renegotiations, and include a well-designed dispute resolution mechanism. Document type: Book
Abstract
To increase investment in infrastructure, in the early 1990s Chiles government introduced private capital into the transport infrastructure sector, covering roads and highways, [...]
- 2
- read
Workplace studies the critical role of workplace studies in cscw
K. Schmidt, K. Schmidt

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

Abstract
Document type: Part of book or chapter of book
- 3
- read
The São Mateus Jabaquara Trolleybusway Concession in Brazil
P. Machado, P. Machado, J. Rebelo, J. Rebelo

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

Abstract
The authors describe how Sao Paulo State granted a 20-year concession for operating a busway, one requirement for which was that the concessionaire replace the diesel bus operation with electric traction (trolleys). This was not a"greenfield concession"but is probably the only"busway"concession undertaken so far worldwide. With roughly 16,000 buses fighting their way through heavy traffic under traffic policies geared to automobiles, bus services was slow and unreliable. Then Sao Paulo adopted certain practices aimed at improving bus operations. Between 1983 and 1987, it implemented a segregated trolleybus corridor between Sao Mateus and Jabaquara, to be opened as a private concession regulated by the state of Sao Paulo. The concession was to operate for 20 years but the winning consortium had to invest in only part of the equipment, because part of it was in place. This made things less risky for the private consortium and allowed thestate to complete an environmentally friendly project with the help of the private sector. The concession has so far been a success - an example to be followed. After an initial increase, demand for the busway began to fall in 1998 and 1999. This was part of a general decline in demand for the bus system because of: a) A drop in jobs resulting from the economic slowdown. b) A growth in the use of automobiles. c) Competition from illegal buses (vans), which offer door-to-door service. The state was late in completing the aerial network for the trolleyway and rehabilitating sections of the roadway. This delayed replacement of diesel buses by trolleybuses. State representatives indicated it might be better in future to find a mechanism through which the concessionaire instead of the state would undertake infrastructure works and would also handle administration of integration terminals. Document type: Book
Abstract
The authors describe how Sao Paulo State granted a 20-year concession for operating a busway, one requirement for which was that the concessionaire replace the diesel bus [...]
- 0
- read
Desarrollos y aplicaciones de modelos de fractura en la escuela de ingenieros de caminos de Barcelona
E. Oñate

Anales de Mecánica de Fractura (2000). Vol. 17, pp. 127-154

Abstract
El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos en la Escuela de Ingenieros de Caminos de Barcelona (EICB) durante los últimos quince años para el análisis no lineal de estructuras. La motivación fundamental para el desarrollo de estos modelos se centra en el análisis de la seguridad de estructuras de hormigón en masa y armado. La mayor parte de los modelos se basan en la teoría de daño continuo y utilizan el método de los elementos finitos para la solución numérica. Los modelos de daño se han extendido y aplicado también con éxito al análisis de diversas estructuras de edificios históricos. Los desarrollos más recientes de estos modelos en la EICB incluyen la predicción de fenómenos de localización en estructuras de hormigón y el análisis del comportamiento no lineal de estructuras con materiales compuestos. De todos estos modelos se presentan en el artículo unas breves pinceladas, las aplicaciones más relevantes y las referencias donde pueden encontrarse los detalles sobre cada caso.
Abstract
El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos [...]
- 0
- read
Adaptivity based on error estimation for viscoplastic softening materials
P. Diez, M. Arroyo, A. Huerta

Mechanics of Cohesive-Frictional Materials (2000). Vol. 5 (2), pp. 87-112

Abstract
This paper focuses on the numerical simulation of strain softening mechanical problems. Two problems arise: (1) the constitutive model has to be regular and (2) the numerical technique must be able to capture the two scales of the problem (the macroscopic geometrical representation and the microscopic behavior in the localization bands). The Perzyna viscoplastic model is used in order to obtain a regularized softening model allowing to simulate strain localization phenomena. This model is applied to quasistatic examples. The viscous regularization of quasistatic processes is also discussed: in quasistatics, the internal length associated with the obtained band width is no longer only a function of the material parameters but also depends on the boundary value problem (geometry and loads, specially loading velocity). An adaptive computation is applied to softening viscoplastic materials showing strain localization. As the key ingredient of the adaptive strategy, a residual type error estimator is generalized to deal with such highly nonlinear material model. In several numerical examples the adaptive process is able to detect complex collapse modes that are not captured by a first, even if fine, mesh. Consequently, adaptive strategies are found to be essential to detect the collapse mechanism and to assess the optimal location of the elements in the mesh.
Abstract
This paper focuses on the numerical simulation of strain softening mechanical problems. Two problems arise: (1) the constitutive model has to be regular and (2) the numerical [...]
- 12
- read
Error estimation including pollution assessment for nonlinear finite element analysis
A. Huerta, P. Diez

Comput. Methods Appl. Mech. Engrg., (2000). Vol. 181 (1-3), pp. 21-41

Abstract
A residual type error estimator for nonlinear finite element analysis is introduced. This error estimator solves local problems avoiding both the computation of the flux jumps and the associated flux splitting procedure. Pollution errors are taken into account by a feedback strategy, that is, an error estimate based on local computations is used as the input of the pollution analysis. This estimator is used in the frame of an adaptive procedure. Numerical examples show that the estimator is able to drive adaptive procedures leading to likely good solutions. Moreover, one of the examples demonstrates that adaptive procedures are essential for complex highly nonlinear mechanical problems because they may discover secondary collapse mechanisms.
Abstract
A residual type error estimator for nonlinear finite element analysis is introduced. This error estimator solves local problems avoiding both the computation of the flux jumps [...]
- 3
- read
Error estimation for adaptive computations on shell structures
P. Diez, A. Huerta

European Journal of Finite Elements (2000). Vol. 9 (1-3), pp. 49-66

Abstract
The finite element discretization of a shell structure introduces two kinds of errors: the error in the functional approximation and the error in the geometry approximation. The first is associated with the finite dimensional interpolation space and it is present in any finite element computation. The latter is associated with the piecewise polynomial approximation of a curved surface and is much more relevant in shell problems than in any other standard 2D or 3D computation. In the shells framework, formerly the quality control of the finite element solution has been carried out using flux projection a posteriori error estimators. This technique exhibits two main drawbacks: 1) the flux smoothing averages stress components over different elements that may have different physical meaning if the tangent planes are different and 2) the error estimation process uses only the approximate solution and hence, the discretized forces and the computational mesh: the data describing the real geometry and load is therefore not accounted for. In this work, a residual type error estimator introduced for standard 2D finite element analysis is generalized to shell problems. This allows to easily account for the real original geometry of the problem in the error estimation procedure and precludes the necessity of comparing generalized stress components between non coplanar elements. This estimator is based on approximating a reference error associated with a refined reference mesh. In order to build up the residual error equation the computed solution must be represented (projected) on the reference mesh. The use of thin shell finite elements requires a proper formulation in order to preclude shear locking. Following an idea of Donea and Lamain, the interpolation of the rotations is not unique and requires a particular technique to transfer the information from the computational mesh to the reference mesh. This technique is also developed in this work and may be used in any adaptive evolution problem where the solution must be transferred from one mesh to another.
Abstract
The finite element discretization of a shell structure introduces two kinds of errors: the error in the functional approximation and the error in the geometry approximation. [...]
- 4
- read
Stabilization of incompressibility and convection through orthogonal sub-scale in finite element methods
R. Codina

Comput. Methods Appl. Mech. Engrg., (2000). Vol. 190 (13-14), pp. 1579-1599

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 [...]
- 7
- read
Analysis of a pressure-stabilized finite element approximation of the stationary Navier-Stokes equations
R. Codina, J. Blasco

Numerische Mathematik (2000). Vol. 87 (1), pp. 59-81

Abstract
The purpose of this paper is to analyze a finite element approximation of the stationary Navier-Stokes equations that allows the use of equal velocity-pressure interpolation. The idea is to introduce as unknown of the discrete problem the projection of the pressure gradient (multiplied by suitable algorithmic parameters) onto the space of continuous vector fields. The difference between these two vectors (pressure gradient and projection) is introduced in the continuity equation. The resulting formulation is shown to be stable and optimally convergent, both in a norm associated to the problem and in the L2 norm for both velocities and pressure. This is proved first for the Stokes problem, and then it is extended to the nonlinear case. All the analysis relies on an inf-sup condition that is much weaker than for the standard Galerkin approximation, in spite of the fact that the present method is only a minor modification of this.
Abstract
The purpose of this paper is to analyze a finite element approximation of the stationary Navier-Stokes equations that allows the use of equal velocity-pressure interpolation. [...]
- 4
- read
Fourier analysis of an equal‐order incompressible flow solver stabilized by pressure gradient projection
G. Buscaglia, F. Basombrío, R. Codina

Int. J. Numer. Meth. Fluids (2000). Vol. 34 (1), pp. 65-92

Abstract
Fourier analysis techniques are applied to the stabilized finite element method (FEM) recently proposed by Codina and Blasco for the approximation of the incompressible Navier–Stokes equations, here denoted by pressure gradient projection (SPGP) method. The analysis is motivated by spurious waves that pollute the computed pressure in start‐up flow simulation. An example of this spurious phenomenon is reported. It is shown that Fourier techniques can predict the numerical behaviour of stabilized methods with remarkable accuracy, even though the original Navier–Stokes setting must be significantly simplified to apply them. In the steady state case, good estimates for the stabilization parameters are obtained. In the transient case, spurious long waves are shown to be persistent when the element Reynolds number is large and the Courant number is small. This can be avoided by treating the pressure gradient projection implicitly, though this implies additional computing effort. Standard extrapolation variants are unfortunately unstable. Comparisons with Galerkin–least‐squares (GLS) method and Chorin's projection method are also addressed
Abstract
Fourier analysis techniques are applied to the stabilized finite element method (FEM) recently proposed by Codina and Blasco for the approximation of the incompressible Navier–Stokes [...]
- 3
- read
A nodal-based implementation of a stabilized Finite Element Method for Incompressible Flow Problems
R. Codina

Int. J. Numer. Meth. Fluids (2000). Vol. 33 (5), pp. 737-766

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 [...]
- 3
- read
On stabilized finite element methods for linear systems of convection-diffusion-reaction equations
R. Codina

Comput. Methods Appl. Mech. Engrg., (2000). Vol. 188 (200), pp. 61-82

Abstract
A stabilized finite element method for solving systems of convection-diffusion-reaction equations is studied in this paper. The method is based on the subgrid scale approach and an algebraic approximation to the subscales. After presenting the formulation of the method, it is analyzed how it behaves under changes of variables, showing that it relies on the law of change of the matrix of stabilization parameters associated to the method. An expression for this matrix is proposed for the case of general coupled systems of equations that is an extension of the expression proposed for a 1D model problem. Applications of the stabilization technique to the Stokes problem with convection and to the bending of Reissner-Mindlin plates are discussed next. The design of the matrix of stabilization parameters is based on the identification of the stability deficiencies of the standard Galerkin method applied to these two problems.
Abstract
A stabilized finite element method for solving systems of convection-diffusion-reaction equations is studied in this paper. The method is based on the subgrid scale approach [...]
- 17
- read
Stabilized finite element method for the transient Navier–Stokes equations based on a pressure gradient projection
R. Codina, J. Blasco

Comput. Methods Appl. Mech. Engrg., (2000). Vol. 182 (3-4), pp. 277-300

Abstract
In this paper we present a stabilized finite element formulation for the transient incompressible Navier–Stokes equations. The main idea is to introduce as a new unknown of the problem the projection of the pressure gradient onto the velocity space and to add to the incompresibility equation the difference between the Laplacian of the pressure and the divergence of this new vector field. This leads to a pressure stabilization effect that allows the use of equal interpolation for both velocities and pressures. In the case of the transient equations, we consider the possibility of treating the pressure gradient projection either implicitly or explicity. In the first case, the number of unknowns of the problem is substantially increased with respect to the standard Galerkin formulation. Nevertheless, iterative techniques may be used in order to uncouple the calculation of the pressure gradient projection from the rest of unknowns (velocity and pressure). When this vector field is treated explicitly, the increment of computational cost of the stabilized formulation with respect to the Galerkin method is very low. We provide a stability estimate for the case of the simple backward Euler time integration scheme for both the implicit and the explicit treatment of the pressure gradient projection.
Abstract
In this paper we present a stabilized finite element formulation for the transient incompressible Navier–Stokes equations. The main idea is to introduce as a new unknown [...]
- 10
- read
A finite element method for fluid-structure interaction with surface waves using a finite calculus formulation
E. Oñate, J. García-Espinosa

(2000). Research Report, Nº PI180

Abstract
A stabilized semi-implicit step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized governing equations for the viscous fluid and the free surface are derived at a differential level via finite increment calculus procedure. A mesh updating technique based on solving a fictitious elastic problem on the moving mesh is described. Examples of the efficiency of the stabilized semi-implicit algorithm for the analysis of fluid-structure interaction problems in totally or partially submerged bodies is presented.
Abstract
A stabilized semi-implicit step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized governing [...]
- 10
- read
Stabilization techniques for finite element analysis of convection-diffusion problems
E. Oñate, M. Manzan

(2000). Research Report, Nº PI183

Abstract
The accurate solution of convection type problems on practical grids has been ever a challenging issue, and invariably some sort of stabilization is needed in order to get a physical solution. This has pushed researchers to develop various stabilization algorithms used in every day practice by numerical analysts. In this chapter some methods are presented along with a new finite increment calculus approach to obtain the different algorithms using higher order conservation equations.
Abstract
The accurate solution of convection type problems on practical grids has been ever a challenging issue, and invariably some sort of stabilization is needed in order to get [...]
- 8
- read
The Monte Carlo method. Application to the stochastic analysis of sheet stamping processes
J. Hurtado, F. Zárate, E. Oñate

(2000). Research Report, Nº PI184

Abstract
Stochastic Mechanics is a rapidly growing area of research, whose importance is being recognized not only in academic circles but also in industrial practice. This is no doubt due to the fact that most structural properties and loads are either random or uncertain. The first term refers to a natural chaotic variation of the parameter, while the second is associated to the human lack of knowledge about it. Both kinds of unpredictability work together in rendering doubtful the results of a (usually single) deterministic mechanical analysis. When thinking about the randomness and uncertainty linked to all physical parameters and phenomena a big question mark closes the large list of numbers produced by a finite element calculation. In Stochastic Mechanics there are several techniques to analyse the natural scatter of strains and stresses caused by the dispersion in the given loads and/or the structural parameters. The most general one is the Monte Carlo method. However, it must be recognized that is as well the most costly in computational terms. Nevertheless, this cost has becoming feasible with the advance in Computer Science, specially with the advent of parallel computing, due to the fact that a Monte Carlo calculation is intrinsically a task that can be performed in parallel. The present report is intended to provide the reader an introduction to the Monte Carlo method in the context of Computational Mechanics. The technique is applied to the analysis of the uncertainty spread in a stamping process. The first chapter summarises the Monte Carlo method and its theoretical backgrounds. The second chapter is devoted to the case study, namely, the stochastic analysis of a square cup deep drawing problem. Finally, the basic equations governing the mechanical modelling of the stamping process are summarized in the appendix.
Abstract
Stochastic Mechanics is a rapidly growing area of research, whose importance is being recognized not only in academic circles but also in industrial practice. This is no doubt [...]
- 6
- read
Stabilized finite element approximation of transient incompressible flows using orthogonal subscales
R. Codina

(2000). Research Report, Nº PI185

Abstract
In this paper we present a stabilized finite element formulation to solve the Oseen equations as a model problem involving both convection effects and the incompressibility restriction. The need for stabilization techniques to solve this problem arises because of the restriction in the possible choices for the velocity and pressure spaces dictated by the inf-sup condition, as well as the instabilities encountered when convection is dominant. Both can be overcome by resorting from the standard Galerkin method to a stabilized formulation. The one presented here is based on the subgrid scale concept, in which unresolvable scales of the continuous solution are approximately accounted for. In particular, the approach developed herein is based on the assumption that unresolved subscales are orthogonal to the finite element space. The motivation of the method is fully described. It is also shown that this formulation is table and optimally convergent for an adequate choice of the algorithmic on which the method depends.
Abstract
In this paper we present a stabilized finite element formulation to solve the Oseen equations as a model problem involving both convection effects and the incompressibility [...]
- 6
- read
Pressure stability in fractional step finite element methods for incompressible flows
R. Codina

(2000). Research Report, Nº PI186

Abstract
The objective of this paper is to analyze the pressure stability of fractional step finite element methods for incompressible flows. For the classical first order projection method, it is shown that there is a pressure control which depends on the time step size, and therefore there is a lower bound for this time step for stability reasons. The situation is much worse for a second order scheme in which part of the extremely weak. To overcome these shortcomings, a stabilized fractional step finite element method is also considered, and its stability is analyzed. Some simple numerical examples are presented to support the theoretical results.
Abstract
The objective of this paper is to analyze the pressure stability of fractional step finite element methods for incompressible flows. For the classical first order projection [...]
- 8
- read
Implementation of a stabilized finite element formulation for the incompressible Navier-Stokes equations based on a pressure gradient projection
R. Codina, J. Blasco, G. Buscaglia, A. Huerta

(2000). Research Report, Nº PI187

Abstract
We discuss in this paper some implementation aspects of a finite element formulation for the incompressible Navier-Stokes which allows the use of equal order velocity-pressure interpolations. The method consists in introducing the project of the pressure gradient and adding the difference between the pressure Laplacian and divergence of this new field to the incompressibility equations, both multiplied by suitable algorithmic parameters. The main purpose of this paper is to discuss how to deal with the new variable in the implementation of the algorithm. Obviously, it could be treated as one extra unknown, either explicitly or as a condensed variable. However, we take for granted that the only way or another. Here we discuss some iterative schemes to perform this uncoupling of the pressure gradient projection (PGP) from the calculation of the velocity and the pressure, both for stationary and the transient of the linearization loop and the iterative segregation of the PGP, whereas in the second the main dilemma concerns the explicit or implicit treatment of the PGP.
Abstract
We discuss in this paper some implementation aspects of a finite element formulation for the incompressible Navier-Stokes which allows the use of equal order velocity-pressure [...]
- 4
- read
Prediction of damage and failure in civil engineering structures using a finite element model.
E. Oñate, A. Hanganu, J. Canet

(2000). Research Report, Nº PI188

Abstract
The paper describes a finite element damage model for non linear analysis of concrete or reinforced structures. It is show how can be effectively used to predict local and global damage up to structural failure. Examples of applications of the model to the analysis of different structures such as a nuclear containment shell, a housing building and the domes of St. Mark Basilica are presented.
Abstract
The paper describes a finite element damage model for non linear analysis of concrete or reinforced structures. It is show how can be effectively used to predict local and [...]
- 8
- read
Rigid-flexible body analysis without rotation parameters
R. Taylor

(2000). Research Report, Nº PI189

Abstract
This paper addresses the coupled flexible and rigid body response of solids undergoing large motions and deformations. The formulation is presented in a form which is free of rotation parameters and thus avoids the need of finding compatible integration formulae for translations and rotations. The motion of each rigid body is represented in terms of the nodal parameters of a simplex element subject to constraints which ensure rigid motions. Flexible structural members for rods and shells are then expressed in terms of displacement and relative displacement parameters leading to total system of equations involving only translation degrees of freedom. The motions are integrated using classical energy and momentum conserving schemes, thus leading to systems which are unconditionally stable for Hamiltonian (elastic-rigid) systems. The only requirement for absolute stability is that the non-linear algebraic equations representing the solution at each time step must converge. The formulation is illustrated in two dimensions by representative numerical problems which involve both rigid and flexible parts or multi-rigid body situations. In all cases the conservation properties are observed.
Abstract
This paper addresses the coupled flexible and rigid body response of solids undergoing large motions and deformations. The formulation is presented in a form which is free [...]
- 6
- read
Locking in the incompressible limit for the element free galerkin method
A. Huerta, S. Fernández-Méndez

(2000). Research Report, Nº PI190

Abstract
Volumetric locking (locking in the incompressible limit) for linear elastic isotropic materials is studied in the context of the Element Free Galerkin method. The modal analysis developed here shows here shows that the number of non-physical locking modes is independent of the dilation parameter (support of the interpolation functions). Thus increasing the dilation parameter does not suppress locking. Nevertheless, an increase in the dilation parameter does reduce the energy associated to the non-physical locking behavior. Although more locking modes are present in the Element Free Galerkin method with quadratic consistency than with the standard biquadratic finite element method. Finally, numerical examples are shown.
Abstract
Volumetric locking (locking in the incompressible limit) for linear elastic isotropic materials is studied in the context of the Element Free Galerkin method. The modal analysis [...]
- 7
- read
Límites de los métodos numéricos
E. Oñate

(2000). Research Report, Nº PI191

Abstract
Se plantean en el artículo los límites de los métodos numéricos para resolver cualquier problema que afecte a la vida del hombre. Se discute la capacidad de la razón para expresar todos los problemas del universo en forma matemática, y la posibilidad de encontrar su solución en forma numérica. Finalmente, se especula sobre el alcance y posibilidad de los métodos numéricos en el amplio campo de las ciencias sociales
Abstract
Se plantean en el artículo los límites de los métodos numéricos para resolver cualquier problema que afecte a la vida del hombre. Se discute la [...]
- 77
- read
El bucle de los números
E. Oñate

(2000). Research Report, Nº PI192

Abstract
El artículo presenta una sucinta panorámica sobre la evolución de los métodos numéricos dese la antigua Babilonia hasta nuestros días. Se destaca como la máxima Pitagórica de que “todo es número”, adquiere plena actualidad en nuestros días, en que, con la ayuda de los ordenadores, podemos dar respuestas numéricas a prácticamente cualquier problema que afecte a la vida del hombre. Recorriendo ese bucle de los números se relata brevemente en el artículo como la humanidad ha evolucionado paralelamente en su aspiración de cuantificar los fenómenos de la naturaleza, y como el paso de los pueblos ha ido de la mano de los avances en expresar numéricamente la solución de sus problemas más cotidianos.
Abstract
El artículo presenta una sucinta panorámica sobre la evolución de los métodos numéricos dese la antigua Babilonia hasta nuestros días. [...]
- 4
- read
Simulación por ordenador del comportamiento resistente de estructuras: El laboratorio virtual de estructuras
E. Oñate, A. Hanganu, J. Miquel, B. Suárez

(2000). Research Report, Nº PI193

Abstract
Se presenta el concepto de Laboratorio Virtual de Estructuras (LAVE) para evaluar por ordenador la capacidad resistente de estructuras de hormigón y el coeficiente de seguridad al colapso utilizando modelos de cálculo no lineal basados en la teoría del daño y el método de elementos finitos. Se describen diversos ejemplos de aplicación del LAVE al análisis de la resistencia última de estructuras de hormigón en masa y armado.
Abstract
Se presenta el concepto de Laboratorio Virtual de Estructuras (LAVE) para evaluar por ordenador la capacidad resistente de estructuras de hormigón y el coeficiente [...]
- 7
- read
Del ábaco de fichas a Internet
E. Oñate

(2000). Research Report, Nº PI194
- 2
- read
The braid of numbers
E. Oñate

(2000). Research Report, Nº PI195
- 1
- read
Meshless analysis of incompressible flows using the Finite Point Method
E. Oñate, C. Sacco, S. Idelsohn

(2000). Research Report, Nº PI196

Abstract
A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flows is presented. The stabilization approach is based in the finite calculus (FIC) procedure. An enhanced fractional step procedure allowing the semi-implicit numerical solution of incompressible fluids using the PFM is described. Examples of application of the stabilized FPM to the solution of incompressible flows problems are presented.
Abstract
A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flows is presented. The stabilization approach is based in the finite calculus (FIC) procedure. [...]
- 3
- read
Stabilized finite element approximation of transient incompressible flows using orthogonal subscales
R. Codina

(2000). Research Report, Nº PI197

Abstract
In this paper we present a stabilized finite element method to solve the transient Navier-Stokes equations based on the decomposition of the unknowns into resolvable and sub grid scales. The latter are approximately accounted for, so as to end up with a stable finite element problem which, in particular, allows to deal with convection-dominated flows and the use of equal velocity-pressure interpolations. Three main issues are addressed. The first is a method to estimate the behavior of the stabilization parameters based on a Fourier analysis of the problem for the subscales. Secondly, the way to deal with transient problems discretized using a finite difference scheme is discussed. Finally, the treatment of the nonlinear term is also analyzed. A very important feature of this work is that the sub grid scales are taken as orthogonal to the finite element space. In the transient case, this simplifies considerably the numerical scheme.
Abstract
In this paper we present a stabilized finite element method to solve the transient Navier-Stokes equations based on the decomposition of the unknowns into resolvable and sub [...]
- 13
- read
On isotropic scalar damage models for the numerical analysis of concrete structures
R. Faria, J. Oliver, M. Cervera

(2000). Research Report, Nº PI198

Abstract
Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This scalar damage model is based on the assumption that a stress split is required to capture unilateral behaviour exhibited by concrete when passing from tension to compression. Similar assumptions are pursued on many scalar damage models, yet with many differences being encountered on the strategies adopted for the implementation of such split, which sometimes is performed over the strain tensor. In this paper a discussion on the implications of those splits is conducted, as well as on the norms that define the elastic domain in the stress space. For the proposed damage model a strain-driven formalism is adopted, but the stress split is performed on the effective elastic stress tensor, which is shown to correspond to a split of the Cauchy stress tensor. This strategy improves the algorithmic efficiency as much as required for the seismic analysis of large-scale problems, and circumvents many of the drawbacks present in similar damage models. Besides, two scalar damage variable are introduced as internal variables, as well as an inelastic strain tensor. Efficiency of the proposed constitutive model is illustrated through numerical applications. Algorithmic implementation is also detailed.
Abstract
Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This [...]
- 42
- read
Interface GiD-SAP90 elemento ASOLID
J. Maristany, F. Salinas, A. Mestre

(2000). Research Report, Nº PI199
- 4
- read
Desarrollos y aplicaciones de modelos de fractura en la escuela de ingenieros de caminos de Barcelona
E. Oñate

(2000). Research Report, Nº PI201

Abstract
El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos en la Escuela de Ingenieros de Caminos de Barcelona (EICB) durante los últimos quince para el análisis no lineal de estructuras. La motivación fundamental para el desarrollo de estos modelos se centra en el análisis de la seguridad de estructuras de hormigón en masa y armado. La mayor parte de los modelos se basan en la teoría de daño continuo y utilizan el método de los elementos finitos para la solución numérica. Los modelos de daño se han extendido y aplicado también con éxito el análisis de diversas estructuras de edificios históricos. Los desarrollos más recientes de estos modelos en la EICB incluyen la predicción de fenómenos de localización en estructuras de hormigón y el análisis del comportamiento no lineal de estructuras con materiales compuestos. De todos estos modelos se presentan en el artículo unas breves pinceladas, las aplicaciones más relevantes y las referencias donde pueden encontrarse los detalles de cada caso.
Abstract
El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos [...]
- 11
- read
Stabilization techniques for finite element analysis of convection-diffusion problems
E. Oñate, M. Manzan

(2000). Convection Heat Transfer, B. Sundén and G. Comini (Eds.), WIT Press, Southampton, United Kingdom

Abstract
The accurate solution of convection type problems on practical grids has been ever a challenging issue, and invariably some sort of stabilization is needed in order to get a physical solution. This has pushed researchers to develop various stabilization algorithms used in every day practice by numerical analysts. In this chapter some methods are presented along with a new finite increment calculus approach to obtain the different algorithms using higher order conservation equations.
Abstract
The accurate solution of convection type problems on practical grids has been ever a challenging issue, and invariably some sort of stabilization is needed in order to get [...]
- 15
- read
Simulation of Construction of RCC Dams. II: Stress and Damage
M. Cervera, T. Prato, J. Oliver

Journal of Structural Engineering (2000). 126 (9), pp. 1062-1068

Abstract
The increasing number of roller compacted concrete (RCC) dams being built around the world demands accurate methodologies for the realistic short- and long-term evaluations of the risk of thermally induced cracking in these constructions. In this work a numerical procedure for the simulation of the construction process of RCC dams is presented. It takes into account the more relevant features of the behavior of concrete at early ages, such as hydration, aging, creep, and damage. A 2D model of the Urugua-;aaı RCC Dam, built in Argentina, is used to perform the corresponding analyses. In this second part of the paper, the mechanical aspects of the simulation are presented; long-term effects are included by incorporating a creep model that naturally accounts for the aging effects, and the risk of tensile damage is also considered. The methodology determines the stress field inside the dam at any time during the construction and in the following years. Results for the reference case assess the suitability of the adopted design. This is compared to alternative studies considering different construction schedules to conclude that for these cases changes should be introduced in the dam design.
Abstract
The increasing number of roller compacted concrete (RCC) dams being built around the world demands accurate methodologies for the realistic short- and long-term evaluations [...]
- 13
- read
Simulation of Construction of RCC Dams. I: Temperature and Aging
M. Cervera, J. Oliver, T. Prato

Journal of Structural Engineering (2000). 126 (9), pp. 1053-1060

Abstract
The increasing number of roller compacted concrete (RCC) dams being built around the world demands accurate methodologies for the realistic short- and long-term evaluations of the risk of thermally induced cracking in these constructions. In this work a numerical procedure for the simulation of the construction process of RCC dams is presented. It takes into account the more relevant features of the behavior of concrete at early ages, such as hydration, aging, creep, and damage. A 2D model of the Urugua-í RCC Dam, built in Argentina, is used to perform the corresponding analyses. In this first part only the thermochemical aspects of the simulation of the construction process are presented. The temperature distribution and evolution inside the dam are obtained before and after the completion of the dam. The evolution of the compressive and tensile strengths and elastic moduli and their final distribution inside the dam can also be predicted. Results from 2D and simplified vertical 1D models are compared to assess the validity of the latter, 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
The increasing number of roller compacted concrete (RCC) dams being built around the world demands accurate methodologies for the realistic short- and long-term evaluations [...]
- 16
- read
Reseñas
Comunicar. Media Education Research Journal (2000). Vol. 8, (2), 65
- 0
- read
Apuntes
Comunicar. Media Education Research Journal (2000). Vol. 8, (2), 64
- 0
- read
Plataformas
Comunicar. Media Education Research Journal (2000). Vol. 8, (2), 63
- 0
- read
Informaciones
Comunicar. Media Education Research Journal (2000). Vol. 8, (2), 62
- 0
- read
Posibilidades y limitaciones de la integración de los medios en la enseñanza
R. Romero Tena

Comunicar. Media Education Research Journal (2000). Vol. 8, (2), 61

Abstract
Los datos que se ofrecen en este artículo recogen aspectos considerados fundamentales en la integración de medios y/o nuevas tecnologías a través de los Grupos de Trabajo como actividad de autoperfeccionamiento. Éstos están muy relacionados con la particularidad de las zonas (centros), elemento que no está siendo considerado y que puede repercutir negativamente en las iniciativas que se están teniendo en la incorporación de estos medios. Por ello, se presentan datos concretos sobre zonas diferenciadas en una provincia (Huelva), así como las implicaciones que suponen estos hallazgos a la hora de comprender el significado de la contextualización.
Abstract
Los datos que se ofrecen en este artículo recogen aspectos considerados fundamentales en la integración de medios y/o nuevas tecnologías a través de los Grupos de Trabajo [...]
- 2
- read
El diario, un instrumento para la construcción de los saberes sociales
A. Fleitas, R. Zamponi

Comunicar. Media Education Research Journal (2000). Vol. 8, (2), 60

Abstract
Este trabajo presenta los resultados de la investigación realizada con la totalidad de las Escuelas Municipales de la ciudad de Córdoba (Argentina), a partir del Programa «El diario como apoyo educativo», experiencia realizada a través de un convenio firmado entre el Ministerio de Educación y Cultura de la provincia de Córdoba y el diario «La Voz del Interior» de la ciudad ya mencionada. Este programa, cuyo objetivo es incorporar el diario como recurso para estimular una lectura activa, reflexiva y crítica, se caracteriza por capacitar a educadores en particular, a la comunidad educativa en general, y por trabajar directamente con los alumnos de los distintos niveles del sistema educativo.
Abstract
Este trabajo presenta los resultados de la investigación realizada con la totalidad de las Escuelas Municipales de la ciudad de Córdoba (Argentina), a partir del Programa [...]
- 3
- read