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Modeling of Freeway Traffic
(2004)
An integrated modeling of freeway traffic is developed, whose implementation in an uniform computer –aided simulation model facilitate comparative evaluation and systematic coupling of several traffic simulations, traffic controls, traffic measurements and traffic scenarios. The integrated modeling of freeway traffic is a basic mapping of freeway networks, control methods, measurements and different simulations of traffic flow...
Development of Urban Land Use Model to Compare Transit-Oriented and Automobile-Oriented Cities
(2004)
This study is an attempt to develop a simple simulation model that can compare the differences between automobile-oriented and transit-oriented cities, and clarify the difference between city forms by transportation modes. Following a theoretical model development, a series of simulation runs are tried. The model allocates people who commute to CBD from residential zones along a transportation corridor. As a result of many simulation analyses, it is shown that automobiles need much more traffic space in comparison with the transit as is shown by the proposed traffic space ratio both in CBD and along the corridor.
This paper presents an innovative software platform OpenSTEP intended to build advanced distributed integrated systems and to conduct multidisciplinary collaborative projects in both academy and industry. The paper discusses an open system architecture, methodology, component library and CASE toolkit enabling the developers to build a wide range of interoperable applications and systems compliant with STEP and, particularly, with IFC becoming the increasingly important standard for information integration in architecture, engineering and construction.
A wide variety of behavioural models exist in microscopic traffic simulation. Commercial programms often use closed-source policies and are confined to their respective simulation platforms. Open-source approaches mainly focus on distinctive, highly specialized traffic situations. In the scope of this paper, an open-source framework for developing modular, objectoriented simulation systems is presented, capable of simultaneously accommodating different driving models and enabling the user to modify and extend the catalogue of driving behaviours. The existing driving behaviours and the computational implementation of the simulation are being described.
This paper presents the combination of two different parallelization environments, OpenMP and MPI, in one numerical simulation tool. The computation of the system matrices and vectors is parallelized with OpenMP and the solution of the system of equations is done with the MPIbased solver MUMPS. The efficiency of both algorithms is shown on several linear and nonlinear examples using the Finite Element Method and a meshless discretization technique.
Effective knowledge management is increasingly considered as a cornerstone of sustainable business success. Knowledge management systems are strategically valuable for both ensuring consistency and continuous improvement of various aspects such as quality delivery, productivity and competitiveness. The small and medium enterprises (SMEs) in the construction industry are mostly operating under tighter timeframes, narrower profit margins and more constrained resources. Hence the recently commenced SMILE-SMC (Strategic Management with Information Leveraged Excellece for Small and Medium Contractors) project aims to support the information and knowledge management needs of the small and medium contractors in Hong Kong. This paper presents some snapshots on the SMILE-SMC project, and its conceptualized deliverables with some highlights of recent developments.
Civil engineering decision support systems (construction, building life cycle, refurbishment, total quality management, innovation, etc.) created in Lithuania are described in this paper. The above decision support systems comprise of the following constituent parts: data (database and its management system), models (model base and its management system) and a user interface. Presentation of information in databases may be in conceptual (digital, textual, graphical, photographic, video) and quantitative forms. Quantitative information presented involves criteria systems and subsystems, units of measurement, values and initial weight fully defining the variants provided. The databases were developed providing a multiple criteria analysis of alternatives from economical, infrastructure, technical, technological, qualitative, legislative, social and other perspectives. This information is provided in a user-oriented way. Since the analysis of alternatives is usually performed by taking into account economical, infrastructure, technical, technological, qualitative and other factors, a model-base include models which enable a decision maker to carry out a comprehensive analysis of the variants available and make a proper choice. These systems, related questions and practical case study were analysed the paper.
This paper presents an evaluation system for steel structures of hydroelectric power stations, including hydraulic gates and penstocks, based on Fault Tree Analyasis (FTA) and performance maps. This system consists of fault tree diagrams of FTA, performance maps, design and analysis systems, and engineerin databases. These four modules are integrated by appropriate hyperlinks so that the user of this system can use it easily and seamlessly. A well developed system was applied to some illustrative example cases, and they showed that the developed methodology and system worked well and the users found the system useful and effective for their maintenance tasks at powerstations.
Transport problems, as, for instance, the transport of sediment in hydraulic engineering and the transport of harmful substances through porous media, play an important role in many fields of civil engineering. Other examples include the dissipation of heat or sound as well as the simulation of traffic with macroscopic models. The contribution explains the analysis of the applicability of Voronoi-based finite volume methods for the approximation of solutions of transport problems. A special concern is the discretisation of the transport equation. Current limitations of the method as well as ideas for stabilisation are explained with examples.
Analysis System for Bridge Test (Chinese name abbr.: QLJC) is an application software specially designed for bridge test to analyze the static and dynamic character of bridge structures, calculate efficiency ratio of load test, pick up the results of observation points and so on. In this paper, research content, system design, calculation theory, characteristics and practical application of QLJC is introduced in detail.
The influence of vortex-induces vibrations on vertical tie rods has been proved as a determinant load factor in the lifetime-oriented dimensioning of arched steel bridges. Particularly, the welded connection plates between the suspenders and the arches often exhibit cracks induced primarily rods. In this context, the synchronization of the vortex-shedding to the rod motion in a critical wind velocity range, the so-called lock-in effect, is of essential interest.
The method of the finite elements is an adaptable numerical procedure for interpolation as well as for the numerical approximation of solutions of partial differential equations. The basis of these procedure is the formulation of suitable finite elements and element decompositions of the solution space. Classical finite elements are based on triangles or quadrangles in the two-dimensional space and tetrahedron or hexahedron in the threedimensional space. The use of arbitrary-dimensional convex and non-convex polyhedrons as the geometrical basis of finite elements increases the flexibility of generating finite element decompositions substantially and is sometimes the only way to get a clear decomposition...
In this paper, systematic analyses for the shoring systems installed to support the applied loads during construction are performed on the basis of the numerical approach. On the basis of a rigorous time-dependent analysis, structural behaviors of reinforced concrete (RC) frame structures according to the changes in design variables such as the types of shoring systems, shore stiffness and shore spacing are analyzed and discussed. The time-dependent deformations of concrete such as creep and shrinkage and construction sequences of frame structures are also taken into account to minimize the structural instability and to reach to an improved design of shoring system because these effects may increase the axial forces delivered to the shores. In advance, the influence of the column shortening effect, generally mentioned in a tall building structure, is analyzed. From many parametric studies, it has been finally concluded that the most effective shoring system in RC frame structures is 2S1R (two shores and one reshore) regardless of the changes in design variables.
Development and Analysis of Sparse Matrix Concepts for Finite Element Approximation on general Cells
(2004)
In engineering and computing, the finite element approximation is one of the most well-known computational solution techniques. It is a great tool to find solutions for mechanic, fluid mechanic and ecological problems. Whoever works with the finite element method will need to solve a large system of linear equations. There are different ways to find a solution. One way is to use a matrix decomposition technique such as LU or QR. The other possibility is to use an iterative solution algorithm like Conjugate Gradients, Gauß-Seidel, Multigrid Methods, etc. This paper will focus on iterative solvers and the needed storage techniques...
The paper investigates accuracy of deflection predictions made by the finite element package ATENA and design code methods ACI and EC2. Deflections have been calculated for a large number of experimental reinforced concrete beams reported by three investigators. Statistical parameters have been established for each of the technique at different load levels, separately for the beams with small and moderate reinforcement ratio.
Creation of hierarchical sequence of the plastic and viscoplastic models according to different levels of structure approximations is considered. Developed strategy of multimodel analysis, which consists of creation of the inelastic models library, determination of selection criteria system and caring out of multivariant sequential clarifying computations, is described. Application of the multimodel approach in numerical computations has demonstrated possibility of reliable prediction of stress-strain response under wide variety of combined nonproportional loading.
Framed-tube system with multiple internal tubes is analysed using an orthotropic box beam analogy approach in which each tube is individually modelled by a box beam that accounts for the flexural and shear deformations, as well as the shear-lag effects. A simple numerical modeling technique is proposed for estimating the shear-lag phenomenon in tube structures with multiple internal tubes. The proposed method idealizes the framed-tube structures with multiple internal tubes as equivalent multiple tubes, each composed of four equivalent orthotropic plate panels. The numerical analysis is based on the minimum potential energy principle in conjunction with the variational approach. The shear-lag phenomenon of such structures is studied taking into account the additional bending moments in the tubes. A detailed work is carried out through the numerical analysis of the additional bending moment. The moment factor is further introduced to identify the shear lag phenomenon along with the additional moment.
The displacements and stresses in arch dams and their abutments are frequently determined with 20-node brick elements. The elements are distorted near the contact plane between the wall and the abutment. A cantilever beam testbed has been developed to investigate the consequences of this distortion. It is shown that the deterioration of the accuracy in the computed stresses is significant. A compatible 18-node wedge element with linear stress variation is developed as an alternative to the brick element. The shape of this element type is readily adapted to the shape of the contact plane. It is shown that the accuracy of the computed stresses in the vicinity of the contact plane is improved significantly by the use of wedge elements.
The primary objective of initial shape analysis of a cable stayed bridge is to calculate initial installation cable tension forces and to evaluate fabrication camber of main span and pylon providing the final longitudinal profile of the bridge at the end of construction. In addition, the initial cable forces depending on the alternation of the bridge’s shape can be obtained from the analysis, and will be used to provide construction safety during construction. In this research, we conducted numerical experiments for initial shape of Ko-ha bridge, which will be constructed in the near future, using three different typical methods such as continuous beam method, linear truss method, and IIMF (Introducing Initial Member Force) method
The paper presents a general map-based approach to prototyping of products in virtual reality environments. Virtual prototyping of products is considered as a consistent simulation and visualization process mapping the source product model into its target visual representations. The approach enables to interrelate formally the product and visual information models with each other by defining mapping rules, to specify a prototyping scenario as a composition of map instances, and then to explore particular product models in virtual reality environments by interpreting the composed scenario. Having been realized, the proposed approach provides for the strongly formalized method and the common software framework to build virtual prototyping applications. As a result, the applications gain in expressiveness, reusability and reliability, as well as take on additional runtime flexibility...