Showing papers by "Bauhaus University, Weimar published in 2000"

Project Management Topic Coverage in Recent Conferences

Abstract: The paper presents an analysis of the relative frequency of attention to project management body of knowledge topics in papers presented at recent Project Management Institute (PMI®) seminars/sympo...

Festivalization and the media: Weimar, cultural capital of Europe 1999 1

Abstract: Following earlier stages of extensive and intensive urbanization, cities are now responding to processes of de-, reand neo-urbanization, the decline of population and workplaces in the inner city and world wide economic restructuring. The transition from industrial to service economies, the internationalization of capital, the opening of the world market and national boundaries have contributed to an intensified competition among cities. Urban politics react to globalization and competition with new types of local activity. The entrepreneurial city is characterized by enforced economic interventions and the growing support of entrepreneurial initiatives as well as local specific city marketing (Mayer 1990, Hall/Hubbard 1998). This means that cities can no longer perceive themselves as extensions of the nation state or as executive administrations but as 'actors, promoters and managers' of themselves (Dangschat 1995: 53). Typical of this new type of urban politics are the stronger participation of more and more non-state actors, cooperative and horizontal political styles as well as negotiating and decisionmaking processes outside of traditional structures (Mayer 1990). Furthermore, postfordist urban politics are characterized by the fact that less resources are provided for social services and that the

Arno: Constraints Programming in Common Music

Abstract: Constraints programming allows the composer to synthesize a score by describing it. Arno is a program for computer assisted composition which extends Common Music (CM) by means of constraints programming using Screamer. In Arno parameters of CM elements in a CM container can be declared nondeterministically using finite domains — instead of single values. Constraints are expressed as predicates which test one CM object and restrict the actual values of its slots.

Advanced analysis of structural reliability using commercial fe-codes

Abstract: Recent trends in structural mechanics applications of Finite Element codes show an increasing demand for efficient stochastic analysis tools. While in principle virtually all stochastic problems can be solved by Monte-Carlo simulation, the computational cost may be prohibitively large. Therefore more effective approximations based on e.g. the Response Surface Method become quite popular. Alternatively, advanced Monte-Carlo methods such as importance sampling or adaptive sampling can be utilized. Depending on the class of problem to be analyzed, these methods may even be more efficient than the Response Surface Method. The paper focuses on two main issues, i.e. The application of existing code for probabilistic analysis together with existing Finite Element Code for advanced Monte Carlo analysis Presentation of a local-global approximation strategy for the response surface method. This so-called "weighted radii" approximation appears to provide the flexibility and ac- curacy needed for the reliability analysis of complex structures. A numerical example from structural analysis under static loading conditions shows the applicability of these concepts. In particular, the stochastics package SL ang is utilized together with the FE-code ANSYS in the context of geometrically and materially nonlinear analysis.

EXTRA - a new experiment supported condition assessment method for concrete bridges

Abstract: In Germany a group of researchers from four universities has developed an advanced experiment supported state assessment method for short and midspan concrete bridges under the term 'EXTRA.' As a background for this work are the deficiencies of many bridges on one hand and the rising disproportions between available funds and costs for demolition and rebuilding on the other. The presented method can be used preferably in such cases, where conventional assessment methods cannot be applied successfully. The fundamental idea of this method is to determine the ultimate testing load UTL of the structure. This UTL is defined as that load, which just not reaches a level which would cause damages in the tested structure. The level of UTL can be considerably higher than the safe load. For identification the UTL special criterions has been developed. From the UTL afterwards the safe load can be derived by safety considerations. A guideline for practical use of the method for building structures will be available shortly; another one for bridges will be prepared in the near future. Methodical and technical conditions and tasks for preparation and practical realization of the test will be introduced. Main subjects are safety aspects, needed theoretical and practical pre-investigations, the test program, different criterions for UTL-identification, the loading regime and corresponding on- line information on the building response In connection with the presentation of a selected application example experiences on the co-operation with owners, authorities and uninvolved colleagues will be discussed and advises on further developments will be given. Acknowledgements finalize the contribution.

Surface digitizations by dilations which are tunnel-free

Abstract: In this article we study digital topology with methods from mathematical morphology. We introduce reconstructions by dilations with appropriate continuous structural elements and prove that notions known from digital topology can be defined by continuous properties of this reconstruction. As a consequence we determine the domains for tunnel-free surface digitizations. It will be proven that the supercover and the grid-intersection digitization of every surface with or without boundary is always tunnel-free.

Load carrying behavior of prestressed bolted steel flanges considering random geometrical imperfections

Abstract: Prestressed ring flanges are frequently used in slender structures subjected to wind loads such as chimneys or wind turbine towers. The alternating forces due to wind can cause both fatigue failure and ultimate load failure of the bolts. For the design of such connections it is therefore important to take into account possible variations of the bolt forces. Due to manufacturing tolerances the contact surfaces are not ideally plane. While the initial forces (under dead load only) in the bolts can be considered deterministic and uniformly distributed along the circumference of the tube, the forces will be redistributed non-uniformly in the presence of lateral loads. This is a consequence of the non-uniform prestressing state of the flange material. A random field model is assumed to describe the geometry of the contact surface. The mean surface is assumed to be the ideal contact plane, deviations are assumed to be log-normally distributed with an exponential spatial correlation function. A Stochastic Finite Element Model with 13,000 DOF and 1500 random variables in conjunction with Monte-Carlo methods is then utilized to derive the statistical properties of the random ultimate load of the joint. It is shown that the effect of imperfect contact surfaces can considerably deteriorate structural performance.

A Borel-Pompeiu Formula in ℂn and Its Application to Inverse Scattering Theory

Abstract: We develop a Borel-Pompeiu formula for functions in several complex variables using Clifford analysis. The obtained formula contains the BochnerMartinelli formula and additional information. The Borel-Pompeiu formula will be used for a new inverse scattering transform in multidimensions.

Supervised lifetime extension of endangered concrete structures by health monitoring

Abstract: State assessment results of conventional or advanced experimental investigations of existing concrete structures (e.g. using the 'EXTRA-'method) are absolutely valid at the time of testing, but usually not longer than a time of at most five to ten years after the testing date. Thereafter the assessment results will be more and more unsure because of progressing (often unknown) deterioration processes. At the latest at that time a repeated (but expensive) test procedure would be necessary. In the most of these cases (but of course also in many other situations) the concept of a supervised lifetime extension by monitoring of a small number of key- measurands would be the more safer and reasonable solution. Since two years the authors have a close cooperation with the aim to develop a remote monitoring system for fields of application like mentioned before. Based on experiences collected on different applications of such a system more general demands on an efficient system configuration could be derived. An overview on the main characteristics is systematized by matrix elements defined by the main demands flexibility, robustness and reliability as well as the main system components hardware, software and application management. Afterwards it will be shown exemplary (system structure, measurement modes, sensor selection criteria, data transmission, data management as well as optional features like solar energy supply or overload truck identification) how the remote monitoring system SMS 2001R is able to fulfill the demands discussed before and which further developments are under way respectively. Finally some experiences from the first presentation of a SMS 2001R in the United States will be added.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

On Some Weighted Spaces of Quaternion-Valued Functions

Abstract: We consider a scale of weighted spaces of quaternion-valued functions of three real variables. This scale generalizes the idea of Q p —spaces of complex function theory using the concept of a hypercomplex derivative of monogenic functions. The main goal of the paper is to investigate different characterizations of these spaces. At the end we compare the approach via the derivative with a similar scale of Sobolev-like spaces based on a gradient norm.

An adaptive response surface method utilizing error estimates

Abstract: A response surface method is proposed which allows adaptation by reducing the local error betweenthe approximated and the actual limit state surface. The response surface is constructed as a setof n -simplices which interpolate linearly the conditional failure probabilities between determinedpoints of the limit state surface. The local errors are estimated via the di erence between theinterpolated and the actual conditional failure probabilities in the directions of the centroids ofthe n -simplices. Adaptation is then performed by successive subdivisions of the response surfacesuch that the computational e ort is concentrated at response surface parts contributing most tothe absolute error. The proposed method is illustrated for a frame structure discretized by niteelements and a limit state function with convex failure domain. IntroductionNonlinear analysis of realistic engineering structures requires in general the utilizationof numerical methods like nite elements to determine failure or limit states. Therebythe limit state function is available only in implicit form, i.e. it is the outcome ofextensive, iterative numerical calculations. Imbedding these methods in reliabilityassessment procedures is still computational demanding. Therefore, in the past theresponse surface method has been proposed, which allows to approximate the limitstate surface for a small number of determined limit state points. The responsesurface is constructed either by tting \globally" a second or higher order polynomial(Grigoriu, 1982; Rackwitz, 1982), or by utilizing \local" information at the limit statepoints to determine tangent hyper-planes, secant hyper-planes or segment hyper-spheres (Katsuki and Frangopol, 1994; Guan and Melchers, 1997; Roos et al., 2000).However, so far no techniques for improving these response surfaces based on errorestimates of the di erent approximations have been provided.Reliability AnalysisGiven is a vector X=[

Determining Visible Points in a Three-Dimensional Discrete Space

Abstract: A method is proposed which computes the visible points of surfaces in a 3-dimensional discrete space The occlusion of surface points of an object by other object points is determined by shooting a discrete ray from each surface point towards the center of projection considering the intersection of the ray with other object points Since the projection of points onto the viewing plane is done by a continuous mapping, additionally to the discrete ray, the location of the continuous projection ray is examined regarding its location to the surface points that are intersected by the discrete ray

Teamwork Support for Building Design Based on Dynamic Modeling Systems

Abstract: The design of buildings is characterized by a high degree of teamwork. At present, these cooperative aspects are not sufficient supported by means of information technology. The objective of the GroupPlan-System is to investigate groupware techniques for building design based on the technology of distributed objects. The system uses runtime dynamic and domain specific taxonomies to manage the information of the building. It is the intention of the system design to cover most of the relevant parts of the l ifecycle of the building. The asynchronous aspects of cooperation are supported through propagation and notification mechanisms that handle changes of building information, which concerns several design team members. These mechanisms are based on relations between the role specific partial models that represent correspondences of the models. Because the system uses a dynamic model management it is necessary to realize an appropriate concept for the visualization of the model data. The chosen approach is founded on a strict separation of data abstractions and their representation and interaction facilities. Based on that approach it is possible to implement different kinds of WYSIWIS-presentations of the model information, which can be utilized for synchronous teamwork support. Besides, several kinds of tele-presence techniques are integrated to ensure a collaboration support with group awareness.