620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
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Am Fraunhofer ISE wurde in den letzten Jahren die Simulationsumgebung ColSim entwickelt, die sich speziell zur Untersuchung von Regelungssystemen in Gebäudeenergieversorgungssystemen eignet. Zielsetzung des Designs ist die Umsetzung des simulationsbasierten Regelungsentwurfs, der einen unmittelbaren Einsatz der Regelungsmodule auf sog. Enbedded Systems gestattet. Das Simulationswerkzeug zeichnet sich durch die modulare offene Struktur aus, die eine flexible Erweiterung ermöglicht (vgl. TRNSYS [1]). Die Implementierung erfolgte im genormten ANSI-C Code, der einen plattform- unabhänigen Einsatz gewährleistet. Entwicklungsplattform stellt derzeit ein Linux Cluster dar, als Zielplattform wurden bisher sowohl eingebettete Industrie-PCs wie auch klassische Micro- controller Boards verwendet. Die Entwurfsmethode wird anhand einer Systemregelung für eine solarthermische Anlage mit 120m2 Kollektorfläche (SolarThermie2000 Anlage) demonstriert, bei der ein vernetztes Regelungssystem mit Internet-Integration zum Einsatz kommt. Das Regelungssystem verfügt seinerseits über ein Betriebssystem (schlankes embedded linux system), das die Kommunikation nach aussen gestattet. Das Regelungssystem vefügt somit über Klima- bzw Strahlungsdaten, die für den Regelungsprozess von Bedeutung sind. Die externen Informationen können einerseits zur >Einsparung< von Sensorik genutzt werden, andererseits gestatten sie den Einsatz von prädiktiver Regelungsmethodik, um den fossilen (Nachheiz-) Energieeinsatz zu minimieren. Mit Hilfe von simulationstechnischen Systemstudien kann ein adaptives Verhalten des Regelungssystems erprobt werden, das eine selbstständige Strecken- identifikation realieren kann. Beispielsweise soll beim näher beschriebenen solarthermischen System die Totzeit bestimmt werden, die sich infolge der Verrohrung zwischen Speicher und Entladegruppe ergibt. Der Betrieb der Entlade- pumpe wird einerseits in Abhängigkeit der Verfügbarkeit des Pufferwassers erfolgen, andererseits in Abhängigkeit des erwarteten Zapfvolumens durch den Verbraucher. Die vernetzten Regelungssysteme, die auf Basis der Simulationsmodelle ent- wickelt werden, sollen künftig die gesamte Energieflußanalyse des Gebäudes realisieren, wobei eine transparente Darstellung des Systemverhaltens auf Basis einer Internet Visualisierung erfolgt. Der Betreiber und Nutzer wird unmittel- bar durch die Online Dienste (SMS,Email,Fax) über das (fehlerhafte) Anlagen- verhalten informiert. Gerade die sensitiven regenerativen Systeme neigen durch ihre Komplexität zu Störungen, die oftmals nicht erkannt werden, weil die konventionellen Teilsysteme (z.B. Ergasbrenner) den Ausfall in der Regel >kompensieren<.
COMPARISON OF SOME VARIANTS OF THE FINITE STRIP METHOD FOR ANALYSIS OF COMPLEX SHELL STRUCTURES
(2000)
The subject of this paper is to explore and evaluate the semi-analytical, analytical and numerical versions of the finite strip method (FSM) for static, dynamic and stability analyses of complex thin-walled structures. Many of bridge superstructures, some roof and floor structures, reservoirs, channels, tunnels, subways, layered shells and plates etc. can be analysed by this method. In both semi-analytical and analytical variants beam eigenvalue vibration or stability functions, orthogonal polynomials, products of these functions are used as longitudinal functions of the unknowns. In the numerical FSM spline longitudinal displacement functions are implemented. In the semi-analytical and numerical FSM conventional transverse shape functions for displacements are used. In the analytical FSM the accurate function of the strip normal displacement and the plane stress function are applied. These three basic variants of the FSM are compared in quality and quantity in view to the following: basic ideas, modelling, unknowns, DOF, a kind and order of the strips, longitudinal and transverse displacement and stress functions, compatibility requirements, boundary conditions, ways for obtaining of the strip stiffness and load matrices, a kind and size of the structure stiffness matrix and its band width, mesh density, necessary number of terms in length, accuracy and convergence of the stresses and displacements, approaches for refining results, input and output data, computer resources used, application area, closeness to other methods, options for future development. Numerical example is presented. Advantages and shortcomings are pointed. Conclusions are given.
The problem of the computation of stresses and settlements in the half-space under various types of loads is often presented in geotechnical engineering. In 1885 Boussinesq advanced theoretical expressions to determine stresses at a point within an ideal mass. His equation considers a point load on the surface of a semi-infinite, homogeneous, isotropic, weightless, elastic half-space. Newmark in 1942 performed the integration of Boussinesq's equations for the vertical stress under a corner of a rectangular area loaded with a uniform load. The problem of the determination of vertical stresses under a rectangular shaped footing has been satisfactorily solved with renewal integration of the Boussinesq's equation over the arbitrary rectangle on surface of the half-space, with a non-uniform load represented with piecewise linear interpolation functions. The problem of the determination of stresses in the case when the footing shape is an arbitrary quadrilateral however remains unsolved. The paper discusses an approach to the computation of vertical stresses and settlements in an arbitrary point of the half-space, loaded with a uniform load, which shape in the ground plan can be a general four noded form with straight edges. Since the form is transformed into a biunit square and all integrations are performed over this area, all solutions are valid also for an arbitrary triangle by the implementation of the degeneration rule.
Computational Steering provides methods for the integration of modeling, simulation, visualization, data analysis and post processing. The user has full control over a running simulation and the possibility to modify objects (geometry and other properties), boundary conditions and other parameters of the system interactively. The objective of such a system is to explore the effects of changes made immediately and thus to optimize the target problem interactively. We present a computational steering based system for fluid flow problems in civil engineering. It is based on three software components as shown in figure 1. The modeler is the CAD-system AutoCAD, which offers a powerful programming interface allowing an efficient access to the geometric data. It also offers convenient manipulators for geometric objects. The simulation kernel is a Lattice-Boltzmann (LB) solver for the Navier-Stokes equations, which is especially suitable for instationary flows in complex geometries. For the visualization and postprocessing we use the software tool AVS, which provides a powerful programming interface and allows the efficient visualization of flow fields. These three components are interconnected through two communication modules and three interfaces as depicted in figure 1. Interface 1 is responsible for the transformation of the modified system for the simulation kernel, interface 2 is responsible for the proper preparation of the simulation data whereas interface 3 transforms the data from the modeler into a format suitable for the visualization system. The whole system is synchronized by the two communication modules.
Designing lightings in a 3D-scene is a general complex task for building conception as it is submitted to many constraints such as aesthetics or ergonomics. This is often achieved by experimental trials until reaching an acceptable result. Several rendering softwares (such as Radiance) allow an accurate computation of lighting for each point in a scene, but this is a long process and any modification requires the whole scene to be rendered again to get the result. The first guess is empirical, provided by experience of the operator and rarely submitted to scientific considerations. Our aim is to provide a tool for helping designers to achieve this work in the scope of global illumination. We consider the problem when some data are asked for : on one hand the mean lighting in some zones (for example on a desktop) and on the other hand some qualitative information about location of sources (spotlights on the ceiling, halogens on north wall,...). The system we are conceiving computes the number of light sources, their position and intensities, in order to obtain the lighting effects defined by the user. The algorithms that we use bind together radiosity computations with resolution of a system of constraints.
Poland is not situated in any seismic region of the earth, however there are still areas were underground mining is being conducted. In these areas, so-called 'paraseismic tremors', are very frequent phenomena. In the situation when a building examination is realized in order to define its safety, it is necessary to make a complete analysis, in which an influence of tremors should be included. To decide if a building is able to carry out any dynamic loads or not, it is necessary to compute its dynamic characteristics, i.e. natural frequencies. It is not possible using any standard techniques. After diagnosis a building in situ by an expert, computer techniques together with specialized software for dynamic, static, and strength analyses become a suitable tool. In this paper a special attention was paid to a typical twelve-store WGP (Wroclaw Great Plate) prefabricated building, concerning special type of joints. During dynamic actions these joints have a decisive influence on building's behavior. Paraseismic tremors are especially dangerous for these buildings and can be the reason of pre-failure states. It can be difficult and very expensive to prepare laboratory investigations of the part of a building or of a separate joint; therefore the computer modeling suitable to investigate behavior of such elements and whole buildings under different kinds of loads was used.
The paper describes a development of the analytical finite strip method (FSM) in displacements for linear elastic static analysis of simply supported at their transverse ends complex orthotropic prismatic shell structures with arbitrary open or closed deformable contour of the cross-section under general external loads. A number of bridge top structures, some roof structures and others are related to the studied class. By longitudinal sections the prismatic thin-walled structure is discretized to a limited number of plane straight strips which are connected continuously at their longitudinal ends to linear joints. As basic unknowns are assumed the three displacements of points from the joint lines and the rotation to these lines. In longitudinal direction of the strips the unknown quantities and external loads are presented by single Fourier series. In transverse direction of each strips the unknown values are expressed by hyperbolic functions presenting an exact solution of the corresponding differential equations of the plane straight strip. The basic equations and relations for the membrane state, for the bending state and for the total state of the finite strip are obtained. The rigidity matrix of the strip in the local and global co-ordinate systems is derived. The basic relations of the structure are given and the general stages of the analytical FSM are traced. For long structures FSM is more efficient than the classic finite element method (FEM), since the problem dimension is reduced by one and the number of unknowns decreases. In comparison with the semi-analytical FSM, the analytical FSM leads to a practically precise solution, especially for wider strips, and provides compatibility of the displacements and internal forces along the longitudinal linear joints.
As it is well known, the approximation theory of complex valued functions is one of the main fields in function theory. In general, several aspects of approximation and interpolation are only well understood by using methods of complex analysis. It seems natural to extend these techniques to higher dimensions by using Clifford Analysis methods or, more specific, in lower dimensions 3 or 4, by using tools of quaternionic analysis. One starting point for such attempts has to be the suitable choice of complete orthonormal function systems that should replace the holomorphic function systems used in the complex case. The aim of our contribuition is the construction of a complete orthonormal system of monogenic polynomials derived from a harmonic function system by using sistematically the generalized quaternionic derivative
The contribution introduces an adaptable process model to meet the special requirements of the coordination of planning activities in AEC (Architecture, Engineering, Construction). The process model is based on the concept of Coloured Petri-Nets and uses metainformation to characterize process-relevant information and to enable process-control based on the actual results of the planning.
Cost and Schedule Controlling in Relation to Liquidity Management during Construction Projects
(2004)
The present paper describes a software application which can be used for relating the scheduled events of a construction project with the respective financial parameters, leading to an overall improvement in general controlling and liquidity management. For this purpose, existing construction schedules are taken and details of the assignment are recorded. Thus it becomes possible to assess a future payment status should changes in the designated schedule occur.