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- 1997 (31) (remove)
We describe the database requirements of SEED (Software Environment to Support the Early Phases in Building Design). The requirements are typical for a database that intends to support a heterogeneous design support environment consisting of independent software modules with diverse internal design models, requirements not met by any commercial database system. The design and implementation of this database is an integral part of the overall software engineering effort. We describe the SEED approach that integrates external and in-house software based on a shared information model specified in the modeling language SPROUT, which allows for the specification of domains, and classes, relationship types and their behavior, and multiple classifications. The SPROUT run-time system organizes and coordinates the communication between the software modules and the database
A technique for using object-oriented technologies to write structural analysis software has been developed. The structural design information of an individual building is stored in an object-oriented database. A global database provides general design values as material data and safety factors. A class library for load elements has been evolved to model the transfer of loads in a building. This class library is the basis for the development of further classes for other structural elements such as beams, columns or slabs. A software has been developed to monitor the forces transferred from one structural member to another in a building for load cases and combinations according to Eurocode 1. The results of the analysis are stored in the projects database from which a structural design report may be generated. The software was developed under Microsoft Visual C++. The Microsoft Foundation Class Library (MFC) was used to program the Graphical User Interface (GUI). Object Linking and Embedding (OLE) technology is useful to include any type of OLE server objects for example texts written with a word processor or CAD drawings in the structural design report. The Object-Oriented Database Management System (OODBMS) ObjectStore provides services to store the large amount of objects.
For many purposes geometric information about existing buildings is necessary, e.g. planing of conservation or reconstruction. Architectural photogrammetry is a technique to acquire 3D geometric data of buildings for a CAD model from images. In this paper the state of the art in architectural photogrammetry and some developments towards automation are described. The photogrammetric process consists of image acquisition, orientation and restitution. Special attention is put on digital methods, from digital image acquisition to restitution methods, supported by digital image processing. There are a few field of development towards automation, e.g. feature extraction, extraction of edges and lines and the detection of corresponding points. The acquired data may be used in a CAD environment or for visualization in Virtual Reality Models, using digital orthoimages for texture mapping.
This paper concerns schedule synchronization problems in public transit networks. In particular, it consists of three main parts. In the first the subject area is introduced, the terms are defined and framework for optimal synchronization in the form of problem representation and formulation is proposed. The second part is devoted to transfer synchronization problem when passengers changing transit lines at transfer points. The intergrated Tabu Search and Genetic solution method is developed with respect to this specific problem. The third part deals with headways harmonization problem i.e. synchronization of different transit lines schedules on a common segments of routes. For the solution of this problem a new bilevel optimization method is proposed with zones harmonization at the bottom level and co-ordination of zones, by time buffers assigned to timing points, at the upper level. Finally, the synchronization problems are numerically illustrated by real-life examples of the public transport lines in Cracow.
Former achievements for integrated information management have concentrated on interoperability of applications like e.g. CAD, structural analysis or facility management, based on product models introducing additional application independent model layers (core models). In the last years it has become clear, that besides interoperability of autonomous applications, the concurrent processes of model instantiation and evolution have to be modeled, including the relationship to available project resources, persons, legal requirements and communication infrastructure. This paper discusses some basic concepts for an emerging methodology relating the fields of product modeling, project management and workflow systems by elaborating the concept of a process model, which gives a decomposition of the project goals into executable activities. Integrated information management systems should be related to process models to detect pending activities, deadlocks and alternatives of execution. According to the heterogeneous nature of project communication processes, a method for dynamic classification of ad-hoc activities is suggested, that complements predefined highlevel process definitions. In a brief outline of the system architecture, we show how sophisticated information management systems can be broadly made available by using conventional Internet technologies.
The general motivation of this research is to develop software to support the handling of the increased complexity of architectural design. In this paper we describe a system providing general support during the whole process. Instead of only developing design tools we are also addressing the problem of the operating environment of these tools. We conclude that design tools have to be integrated in an open, modular, distributed, user friendly and efficient environment. Two major fields have to be addressed - the development of design tools and the realisation of an integrated system as their operation environment. We will briefly focus on the latter by discussing known technologies in the field of information technology and other design disciplines that can be used to realise such an environment. Regarding the first subject we have to state the need of a detailed tool specification. As a solution we suggest a strategy where the tool functions are specified on the basis of a transformation, where a hierarchical process model is mapped into specifications of different design tools realising appropriate support for all sub-processes of architectural design. Using this strategy the main steps to develop such a support system are: implementation of a framework as basis for the integrated design system decision whether the tool specification are already implemented in available tools in this case these tools can be integrated using known methods for tool coupling otherwise new design tools have to be developed according to the framework
In the superelliptic shell joined to a circular cylinder bending stresses are absent when it is subjected to uniform pressure.Some geometrical characteristics have been found. Expressions for determining stresses in the shell crest(in the singular point of plane type) are suggested. The problem of a theoretical critical buckling load of an elongated shell supported by frames is studied. A critical buckling load for two shells with different specifications was found experimentally.
Methods with the convergence order p 2 (Newton`s, tangent hyperbolas, tangent parabolas etc.) and their approximate variants are studied. Conditions are presented under which the approximate variants preserve their convergence rate intrinsic to these methods and some computational aspects (possibilities to organize parallel computation, globalization of a method, the solution of the linear equations versus the matrix inversion at every iteration etc.) are discussed. Polyalgorithmic computational schemes (hybrid methods) combining the best features of various methods are developed and possibilities of their application to numerical solution of two-point boundary-value problem in ordinary differential equations and decomposition-coordination problem in convex programming are analyzed.
The purpose of this paper is to review model for finite element techniques for non-linear crack analysis of reinforced concrete beams and slabs. The non-linear behaviour of concrete and steel were described. Some calculations of >self-stress< for concrete and reinforced concrete beam was made. Current computational aspects are discussed. Several remarks for future studies are also given. The numerical model of the concrete and reinforced concrete was described. The paper shows the results of calculations on a reinforced concrete plane stress panel with cracks. The non-linear, numerical model of calculations of reinforced concrete was assumed. Using finite elements method some calculations were made. The results of calculations like displacements, stresses and cracking are shown on diagrams. They were compared with experimental results and other finding. Some conclusions about the described model and results of calculation are shown.
Ideally, multiple computational building evaluation routines (particularly simulation tools) should be coupled in real-time to the representational design model to provide timely performance feed-back to the system user. In this paper we demonstrate how this can be achieved effectively and conveniently via homology-based mapping. We consider two models as homologous if they entail isomorphic topological information. If the general design representation (i.e., a shared object model) is generated in a manner so as to include both the topological building information and pointers to the semantic information base, it can be used to directly derive the domain representations (>enriched< object models with detailed configurational information and filtered semantic data) needed for evaluation purposes. As a proof of concept, we demonstrate a computational design environment that dynamically links an object-oriented space-based design model, with structurally homologous object models of various simulation routines.
A Product Model of a Road
(1997)
Many errors and delays frequently appear when data is exchanged between particular tasks in the lifecycle of the road. Inter-task connections are therefore of great importance for the quality of the final product. The article describes a product model of a road wich is the kernel of an integrated information system intended to support all important stages of the road lifecycle: design, evaluation (through different analysis procedures), construction, and maintainance. Since particular tasks are often executed at different places and in different companies, the interconnections are supported by a special metafile which contains all specific data of the product model. The concept of the integrated system is object and component oriented. Additionally, existing conventional program packages are included to support some common tasks (methods). A conventional relational database system as well as an open spatial database system with the relevant GIS functionality are included to support the data structures of the model.
The paper analyses the influence of the effect of inertia on the reliability of production systems. Systems inertia represents the phenomenon of continuing work for some time after the breakdown of one of the former phases. In our considerations, inertia is treated as the time elapsed from the onset of breakdown till the system's inability to work. A special method had to be devised to investigate the effect of inertia in order to evaluate the reliability of production systems and to attempt algorithmization to control the reliability of production system by means of inertia or reserving. The method of reliability analysis is presented only in an inform aspect. The possibilities of increasing reliability of production systems are listed. A comparison of the redundancy method and inertia method is presented. The results of this comparison and simulated investigations of influence of inertia on reliability of system are essential scope of the paper. Selected conclusions are as follows: when inertia approaches the last phase in the system, its influence on the shape of the distribution of the system's ability increases; an increase in inertia causes an increase in the availability of the system which approaches a certain border value; dependence of the average of a system's disability on inertia has a saddle-like character whereas dependence of the number of breakdowns (stoppages) in the system has the nature of an S-curve.
The paper deals with the simulation of the non-linear and time dependent behaviour of complex structures in engineering. Such simulations have to provide high accuracy in the prediction of deformations and stability, by taking into account the long term influences of the non-linear behaviour of the material as well as the large deformation and contact conditions. The limiting factors of the computer simulation are the computer run time and the memory requirement during solving large scale problems. To overcome these problems we use a dynamic-explicit time integration procedure for the solution of the semi-discrete equations of motion, which is very suited for parallel processing. In the paper at first we give a brief review of the theoretical background of the mechanical modelling and the dynamic-explicit technique for the solution of the semi-discrete equations of motion. Then the concept of parallel processing will be discussed . A test example concludes the paper.
For the analysis of arbitrary, by Finite Elements discretized shell structures, an efficient numerical simulation strategy with quadratic convergence including geometrically and physically nonlinear effects will be presented. In the beginning, a Finite-Rotation shell theory allowing constant shear deformations across the shell thickness is given in an isoparametric formulation. The assumed-strain concept enables the derivation of a locking-free finite element. The Layered Approach will be applied to ensure a sufficiently precise prediction of the propagation of plastic zones even throughout the shell thickness. The Riks-Wempner-Wessels global iteration scheme will be enhanced by a Line-Search procedure to ensure the tracing of nonlinear deformation paths with rather great load steps even in the post-peak range. The elastic-plastic material model includes isotropic hardening. A new Operator-Split return algorithm ensures considerably exact solution of the initial-value problem even for greater load steps. The combination with consistently linearized constitutive equations ensures quadratic convergence in a close neighbourhood to the exact solution. Finally, several examples will demonstrate accuracy and numerical efficiency of the developed algorithm.
SLang - the Structural Language : Solving Nonlinear and Stochastic Problems in Structural Mechanics
(1997)
Recent developments in structural mechanics indicate an increasing need of numerical methods to deal with stochasticity. This process started with the modeling of loading uncertainties. More recently, also system uncertainty, such as physical or geometrical imperfections are modeled in probabilistic terms. Clearly, this task requires close connenction of structural modeling with probabilistic modeling. Nonlinear effects are essential for a realistic description of the structural behavior. Since modern structural analysis relies quite heavily on the Finite Element Method, it seems to be quite reasonable to base stochastic structural analysis on this method. Commercially available software packages can cover deterministic structural analysis in a very wide range. However, the applicability of these packages to stochastic problems is rather limited. On the other hand, there is a number of highly specialized programs for probabilistic or reliability problems which can be used only in connection with rather simplistic structural models. In principle, there is the possibility to combine both kinds of software in order to achieve the goal. The major difficulty which then arises in practical computation is to define the most suitable way of transferring data between the programs. In order to circumvent these problems, the software package SLang (Structural Language) has been developed. SLang is a command interpreter which acts on a set of relatively complex commands. Each command takes input from and gives output to simple data structures (data objects), such as vectors and matrices. All commands communicate via these data objects which are stored in memory or on disk. The paper will show applications to structural engineering problems, in particular failure analysis of frames and shell structures with random loads and random imperfections. Both geometrical and physical nonlinearities are taken into account.
In this paper the results of the investigations of the free oscillations of the pre-stressed flexible structure elements are presented . Two cases of the central preliminary stress are investigated : without intermediate fastening of the tie to the flexible element and with the intermediate fastening in the middle of the element length. The given physical model can be applied to the flexible sloping shells and arches, membranes, large space antenna fields (besides flexible elements). The peculiarity of these systems is the possibility of the non-adjacent equilibrium form existence at the definite relations of the physical parameters . The transition from one stable equilibrium form to another, non-adjacent form, may be treated as jump. In this case they are called systems with buckling or the systems with two potential «gaps». These systems commenced the new section of the mathematical physics - the theory of chaos and strange attractors. The analysis of the solutions confirms the received for the first time by the author and given in effect of the oscillation period doubling of the system during the transition from the «small» oscillations relatively center to the >large< relatively all three equilibrium conditions. The character of the frequency (period) dependence on the free oscillation amplitudes of the non-linear system also confirms the received earlier result of the duality of the system behaviour : >small< oscillations possess the qualities of soft system; >large< oscillations possess the qualities of rigid system. The >small< oscillation natural frequency changing, depending on the oscillation amplitudes, is in the internal . Here the frequency takes zero value at the amplitude values Aa and Ad (or Aa and Ae ); the frequency takes maximum value at the amplitude value near point b .The >large< oscillation natural frequency changes in the interval . Here is also observed . The influence of the tie intermediate fastening doesn't introduce qualitative changes in the behaviour of the investigated system. It only increases ( four times ) the critical value of the preliminary tension force
Wissenschaftliches Kolloquium vom 27. bis 30. Juni 1996 in Weimar an der Bauhaus-Universität zum Thema: ‚Techno-Fiction. Zur Kritik der technologischen Utopien'
Priority-rule methods for approximately minimizing the duration of a project subject to minimal and maximal time lags between the activities of the project and limited availability of renewable resources are considered. Such a project can be modelled by a cyclic activity-on-node network. Two generation schemes for constructing feasible schedules are discussed: the serial and parallel schemes. Two different kinds of heuristic procedures are proposed. The sequential or direct method processes the activities or respectively nodes of the project network one after another without considering the strong components separately. The contraction method uses a bottom-up technique. First, a feasible subschedule is determined for each strong component. Second, each strong component is replaced by a single node and the resulting acyclic network is treated by the direct method. In conclusion, some results from an experimental performance analysis of the heuristics are given using a new network generator.
This is a paper about knowledge in design and how to elicit knowledge from design processes. The paper is a preparation for an empirical study of interaction in the design process. Reasonings of three authors - Schön, Broadbent and Lundequist - on design processes is presented. They all have a pragmatic perspective in common, and regard the process as an activity without a definite form. Design is seen as an activity of creating models of forms and shapes, by addressing expert knowledge in a dialogic way to problematic situations. Due to the pragmatic approach I find the pragmatist Dewey´s understanding of knowledge and elecitation of knowledge appropiate for studying design processes. According to him it is possible to build up objectified descriptions of experiences, also of such, which are based on experiences of emotional and intuitive nature. There need not be a definite border, which separates tacit knowledge from explicit knowledge - when it comes to the question of the possibility of verbal descriptions. Tacit knowledge is possible to articulate within pragmatic thinking. The conclusion is, that it is possible to study the tacit knowledge of design processes, and get some qualitative insights useful for theory building. A study of design processes can look at three different forms of knowledge. It appears as a precognitive understanding of the design situation, as integrated in the design activity - seeing the situation as something known - and in the process of creating something new.
Renovation's peculiarities of industrial enterprises in conditions of economic selfsufficiency
(1997)
Probleme of recrienfation of building complex, to the sharp increase of share of reconstruction works, capital repair and modernisation of in-dustrial plants are concidered in this work. The conception of develop-ment and creation of unitified system of expluatation and renovation of industrial plants are worded out. This system is based on date-computer technology and taking into conciderations of real economic relations.