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MODEL OF TRAM LINE OPERATION
(2006)
From passenger's perspective punctuality is one of the most important features of trams operations. Unfortunately in most cases this feature is only insufficiently fulfilled. In this paper we present a simulation model for trams operation with special focus on punctuality. The aim is to get a helpful tool for designing time-tables and for analyzing the effects by changing priorities for trams in traffic lights respectively the kind of track separation. A realization of trams operations is assumed to be a sequence of running times between successive stops and times spent by tram at the stops. In this paper the running time is modeled by the sum of its mean value and a zero-mean random variable. With the help of multiple regression we find out that the average running time is a function depending on the length of the sections and the number of intersections. The random component is modeled by a sum of two independent zero-mean random variables. One of these variables describes the disturbance caused by the process of waiting at an intersection and the other the disturbance caused by the process of driving. The time spent at a stop is assumed to be a random variable, too. Its distribution is estimated from given measurements of these stop times for different tram lines in Kraków. Finally a special case of the introduced model is considered and numerical results are presented. This paper is involved with CIVITAS-CARAVEL project: "Clean and better transport in cites". The project has received research funding from the Community's Sixth Framework Programme. The paper reflects only the author's views and the Community is not liable for any use that may be made of the information contained therein.
Subject of the paper is the realisation of a model based efficiency control system for PV generators using a simulation model. A standard 2-diodes model of PV generator is base of the ColSim model, which is implemented in ANSI C code for flexible code exporting. The algorithm is based on discretisized U-I characteristics, which allows the calculation of string topologies witch parallel and serial PV cells and modules. Shadowing effects can be modelled down to cell configuration using polar horizon definitions. The simulation model was ported to a real time environment, to calculate the efficiency of a PV system. Embedded System technology allows the networked operation and the integration of standard I/O devices. Futher work focus on the adaption of shadowing routine, which will be adapted to get the environment conditions from the real operation.
MODELLING THE PLASTIC HINGE IN THE STATICALLY INDETERMINABLE REINFORCED CONCRETE BAR ELEMENTS
(2006)
The paper presents the example numerical model to calculate the reinforced concrete bar structures. Usually applied methods of structure dimensioning do not include the case of plastic hinges occurrence under the limit load of construction. The model represented by A. Borcz is based on the differential equation of deflection line of the beam and it includes the effects of rearrangement of the internal forces and reological effects. The experimental parameters obtained in earlier investigations describe effects resulting from the rise of plastic hinges in the proposed equation.
The mathematical and technical foundations of optimization have been developed to a large extent. In the design of buildings, however, optimization is rarely applied because of insufficient adaptation of this method to the needs of building design. The use of design optimization requires the consideration of all relevant objectives in an interactive and multidisciplinary process. Disciplines such as structural, light, and thermal engineering, architecture, and economics impose various objectives on the design. A good solution calls for a compromise between these often contradictory objectives. This presentation outlines a method for the application of Multidisciplinary Design Optimization (MDO) as a tool for the designing of buildings. An optimization model is established considering the fact that in building design the non-numerical aspects are of major importance than in other engineering disciplines. A component-based decomposition enables the designer to manage the non-numerical aspects in an interactive design optimization process. A façade example demonstrates a way how the different disciplines interact and how the components integrate the disciplines in one optimization model. In this grid-based façade example, the materials switch between a discrete number of materials and construction types. For light and thermal engineering, architecture, and economics, analysis functions calculate the performance; utility functions serve as an important means for the evaluation since not every increase or decrease of a physical value improves the design. For experimental purposes, a genetic algorithm applied to the exemplary model demonstrates the use of optimization in this design case. A component-based representation first serves to manage non-numerical characteristics such as aesthetics. Furthermore, it complies with usual fabrication methods in building design and with object-oriented data handling in CAD. Therefore, components provide an important basis for an interactive MDO process in building design.
Several results concerning the distribution of the headway of busses in the flow behind a traffic signal are presented. In the main focus of interest is the description of analytical models, which are verified by the results of Monte-Carlo-Methods. The advantage of analytical models (verified, but not derived by simulation methods) is their flexibility with respect to possible generalizations. For instance, several random distributions of the flow incoming to the traffic signal can be compared. The attention will be directed at the question, how the primary headway H (analyzed in front of the traffic signal) is mapped to the headway H’ analyzed behind of the traffic signal and how the random distribution of H is mapped to that of H’. For the traffic flow in front of the traffic signal several models will be discussed. The first case considers the situation, that busses operate on a common lane with the individual motor car traffic and the traffic flow is saturated. In the second situation, busses operate on a separated bus lane. Moreover, a mixed situation is discussed to model as close to reality as possible.
Planning and construction processes are characterized by the peculiarity that they need to be designed individually for each project. It is necessary to set up an individual schedule for each project. As a basis for a new project, schedules from already finished projects are used, but adaptions are always necessary. In practice, scheduling tools only document a process. Schedules cover a set of activities, their duration and a set of interdependencies between activities. The design of a process is up to the user. It is not necessary to specify each interdependency, and completeness and correctness need to be checked manually. No methodologies are available to guarantee properties such as correctness or completeness. The considerations presented in the paper are based on an approach where a planning and a construction process including the interdependencies between planning and construction activities are regarded as a result. Selected information need to be specified by a user, and a proposal for an order of planning and construction activities is computed. As a consequence, process properties such as correctness and completeness can be guaranteed with respect to user input. Especially in Germany, clients are allowed to modify their requirements at any time. This leads to modifications in the planning and construction processes. This paper covers a mathematical formulation for this problem based on set theory. A complex structure is set up covering objects and relations; and operations are defined that guarantee consistency in the underlying and versioned process description. The presented considerations are based on previous work. This paper can be regarded as the next step in a series of previous work describing how a suitable concept for handling, planning and construction processes in civil engineering can be formed.
MULTI-SITE CONSTRUCTION PROJECT SCHEDULING CONSIDERING RESOURCE MOVING TIME IN DEVELOPING COUNTRIES
(2010)
Under the booming construction demands in developing countries, particularly in Vietnam situation, construction contractors often perform multiple concurrent projects in different places. In construction project scheduling processes, the existing scheduling methods often assume the resource moving time between activities/projects to be negligible. When multiple projects are deployed in different places and far from each other, this assumption has many shortcomings for properly modelling the real-world constraints. Especially, with respect to developing countries such as the Vietnam which contains transportation systems that are still in backward and low technical standards. This paper proposes a new algorithm named Multi-Site Construction Project Scheduling - MCOPS. The objective of this algorithm is to solve the problem of minimising multi-site construction project duration under limited available conditions of renewable resources (labour, machines and equipment) combining with the moving time of required resource among activities/projects. Additionally, in order to mitigate the impact of resource moving time into the multi-site project duration, this paper proposed a new priority rule: Minimum Resource Moving Time (MinRMT). The MinRMT is applied to rank the finished activities according to a priority order, to support the released resources to the scheduling activities. In order to investigate the impact of the resource moving time among activities during the scheduling process, computational experimentation was implemented. The results of the MCOPS-based computational experiments showed that, the resource moving time among projects has significantly impacted the multi-site project durations and this amount of time can not be ignored in the multi-site project scheduling process. Besides, the efficient application of the MinRMT is also demonstrated through the achieved results of the computational experiment in this paper. Though the efforts in this paper are based on the Vietnamese construction conditions, the proposed method can be usefully applied in other developing countries which have similar construction conditions.
Requires for reliability and durability of structures and their elements with simultaneous material economy have stimulated improvement of constitutive equations for description of elasto-plastic deformation processes. This has led to the development of phenomenological modelling of complex phenomena of irreversible deformation including history-dependent and rate-dependent effects. During the last several decades many works have been devoted to the development of elasto-plastic models, in order to better predict the material behavior under combined variable thermo-mechanical loading. The increase of accuracy of stress analysis and safety factors for complex structures with the help of modern finite-element packages (ABAQUS, ANSYS, COSMOS, LS-DYNA, MSC.MARC, MSC.NASTRAN, PERMAS and other) can be provided only by use of complex and special variants of plasticity theories, which are adequate for the considered loading conditions and based on authentic information about properties of materials. The areas of application of the various theories (models) are as a rule unknown to the users of finite-element packages at the existing variety loading condition sin machine-building designs. At the moment a universal theory of inelasticity is absent and even the most accomplished theories can not guarantee adequate description of deformation processes for arbitrary structure under wide range of loading programs. The classifier of materials, loading conditions, effects (phenomena) and list of basic experiments are developed by the authors. Use of these classifiers for an establishment of hierarchy of models is a first step for introduction of the multimodel analysis into computational practice. The set of the classic and modern inelasticity theories is considered, so that they are applicable for stress analysis of structures under complex loading programs. Among them there are plastic flow theories with linear and nonlinear isotropic and kinematic hardening, multisurface theories, endochronic theory, holonomic theory, rheologic models, theory of elasto-plastic processes, slip theory, physical theories (single crystal and polycrystalline models) and others. The classification of materials provides rearranging by a degree of homogeneous, chemical composition, level of strength and plasticity, behavior under cyclic loading, anisotropy of properties at initial condition, anisotropy of properties during deformation process, structural stability. The classification of loading conditions takes into consideration proportional and non-proportional loading, temperature range, combination of cyclic and monotonous loading, one-axial, two-axial and complex stress state, curvature of strain path, presence of stress concentrators and level of strain gradient. A unified general form of constitutive equations is presented for all used material models based upon the concept of internal state variables. The wide range of mentioned above inelastic material models has been implemented into finite element program PANTOCRATOR developed by authors (see for details www.pantocrator.narod.ru). Application possibility of different material models is considered both for material element and for complex structures subjected to complex non-proportional loading.
For many applications, nonuniformly distributed functional data is given which lead to large–scale scattered data problems. We wish to represent the data in terms of a sparse representation with a minimal amount of degrees of freedom. For this, an adaptive scheme which operates in a coarse-to-fine fashion using a multiscale basis is proposed. Specifically, we investigate hierarchical bases using B-splines and spline-(pre)wavelets. At each stage a leastsquares approximation of the data is computed. We take into account different requests arising in large-scale scattered data fitting: we discuss the fast iterative solution of the least square systems, regularization of the data, and the treatment of outliers. A particular application concerns the approximate continuation of harmonic functions, an issue arising in geodesy.