@article{VuStaat2004, author = {Vu, Duc-Khoi and Staat, Manfred}, title = {An algorithm for shakedown analysis of structure with temperature dependent yield stress}, year = {2004}, abstract = {This work is an attempt to answer the question: How to use convex programming in shakedown analysis of structures made of materials with temperature-dependent properties. Based on recently established shakedown theorems and formulations, a dual relationship between upper and lower bounds of the shakedown limit load is found, an algorithmfor shakedown analysis is proposed. While the original problem is neither convex nor concave, the algorithm presented here has the advantage of employing convex programming tools.}, subject = {Einspielen }, language = {en} } @article{KuehnHaugnerStaatetal.2004, author = {K{\"u}hn, Raoul-Roman and Haugner, Werner and Staat, Manfred and Sponagel, Stefan}, title = {A Two Phase Mixture Model based on Bone Observation}, year = {2004}, abstract = {An optimization method is developed to describe the mechanical behaviour of the human cancellous bone. The method is based on a mixture theory. A careful observation of the behaviour of the bone material leads to the hypothesis that the bone density is controlled by the principal stress trajectories (Wolff's law). The basic idea of the developed method is the coupling of a scalar value via an eigenvalue problem to the principal stress trajectories. On the one hand this theory will permit a prediction of the reaction of the biological bone structure after the implantation of a prosthesis, on the other hand it may be useful in engineering optimization problems. An analytical example shows its efficiency.}, subject = {Knochen}, language = {en} } @inproceedings{KraftSchneider2005, author = {Kraft, Bodo and Schneider, Gerd}, title = {Semantic Roomobjects for Conceptual Design Support : A Knowledge-based Approach}, isbn = {978-1-4020-3460-2}, year = {2005}, abstract = {In: Computer Aided Architectural Design Futures 2005 2005, Part 4, 207-216, DOI: http://dx.doi.org/10.1007/1-4020-3698-1_19 The conceptual design at the beginning of the building construction process is essential for the success of a building project. Even if some CAD tools allow elaborating conceptual sketches, they rather focus on the shape of the building elements and not on their functionality. We introduce semantic roomobjects and roomlinks, by way of example to the CAD tool ArchiCAD. These extensions provide a basis for specifying the organisation and functionality of a building and free architects being forced to directly produce detailed constructive sketches. Furthermore, we introduce consistency analyses of the conceptual sketch, based on an ontology containing conceptual relevant knowledge, specific to one class of buildings.}, subject = {CAD}, language = {en} } @inproceedings{KraftWilhelms2005, author = {Kraft, Bodo and Wilhelms, Nils}, title = {Visual Knowledge Specification for Conceptual Design}, year = {2005}, abstract = {Proc. of the 2005 ASCE Intl. Conf. on Computing in Civil Engineering (ICCC 2005) eds. L. Soibelman und F. Pena-Mora, Seite 1-14, ASCE (CD-ROM), Cancun, Mexico, 2005 Current CAD tools are not able to support the fundamental conceptual design phase, and none of them provides consistency analyses of sketches produced by architects. To give architects a greater support at the conceptual design phase, we develop a CAD tool for conceptual design and a knowledge specification tool allowing the definition of conceptually relevant knowledge. The knowledge is specific to one class of buildings and can be reused. Based on a dynamic knowledge model, different types of design rules formalize the knowledge in a graph-based realization. An expressive visual language provides a user-friendly, human readable representation. Finally, consistency analyses enable conceptual designs to be checked against this defined knowledge. In this paper we concentrate on the knowledge specification part of our project.}, subject = {CAD}, language = {en} } @inproceedings{KraftRetkowitz2005, author = {Kraft, Bodo and Retkowitz, Daniel}, title = {Operationale Semantikdefinition f{\"u}r konzeptuelles Regelwissen}, year = {2005}, abstract = {In: Forum Bauinformatik 2005 : junge Wissenschaftler forschen / [Lehrstuhl Bauinformatik, Brandenburgische Technische Universit{\"a}t Cottbus. Frank Schley ... (Hrsg.)]. - Cottbus : Techn. Universit{\"a}t 2005. S. 1-10 ISBN 3-934934-11-0 Mittels eines operationalen Ansatzes zur Semantikdefinition wird am Bei-spiel des konzeptuellen Geb{\"a}udeentwurfs ein Regelsystem formalisiert. Dazu werdenzwei Teile, zum einen das Regelwissen, zum anderen ein konzeptueller Entwurfsplan zun{\"a}chst informell eingef{\"u}hrt und dann formal beschrieben. Darauf aufbauend wird die Grundlage f{\"u}r eine Konsistenzpr{\"u}fung des konzeptuellen Entwurfs gegen das Regel-wissen formal angeben}, subject = {CAD}, language = {de} } @article{Staat2005, author = {Staat, Manfred}, title = {Local and global collapse pressure of longitudinally flawed pipes and cylindrical vessels}, year = {2005}, abstract = {Limit loads can be calculated with the finite element method (FEM) for any component, defect geometry, and loading. FEM suggests that published long crack limit formulae for axial defects under-estimate the burst pressure for internal surface defects in thick pipes while limit loads are not conservative for deep cracks and for pressure loaded crack-faces. Very deep cracks have a residual strength, which is modelled by a global collapse load. These observations are combined to derive new analytical local and global collapse loads. The global collapse loads are close to FEM limit analyses for all crack dimensions.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{Staat2005, author = {Staat, Manfred}, title = {Direct finite element route for design-by-analysis of pressure components}, year = {2005}, abstract = {In the new European standard for unfired pressure vessels, EN 13445-3, there are two approaches for carrying out a Design-by-Analysis that cover both the stress categorization method (Annex C) and the direct route method (Annex B) for a check against global plastic deformation and against progressive plastic deformation. This paper presents the direct route in the language of limit and shakedown analysis. This approach leads to an optimization problem. Its solution with Finite Element Analysis is demonstrated for mechanical and thermal actions. One observation from the examples is that the so-called 3f (3Sm) criterion fails to be a reliable check against progressive plastic deformation. Precise conditions are given, which greatly restrict the applicability of the 3f criterion.}, subject = {Einspielen }, language = {en} } @inproceedings{KraftRetkowitz2006, author = {Kraft, Bodo and Retkowitz, Daniel}, title = {Graph Transformations for Dynamic Knowledge Processing}, year = {2006}, abstract = {In: Proceedings of the 39th Annual Hawaii International Conference on System Sciences, 2006. HICSS '06 http://dx.doi.org/10.1109/HICSS.2006.200 The conceptual design phase at the beginning of the building construction process is not adequately supported by any CAD-tool. Conceptual design support needs regarding two aspects: first, the architect must be able to develop conceptual sketches that provide abstraction from constructive details. Second, conceptually relevant knowledge should be available to check these conceptual sketches. The paper deals with knowledge to formalize for conceptual design. To enable domain experts formalizing knowledge, a graph-based specification is presented that allows the development of a domain ontology and design rules specific for one class of buildings at runtime. The provided tool support illustrates the introduced concepts and demonstrates the consistency analysis between knowledge and conceptual design.}, subject = {CAD}, language = {de} } @inproceedings{KraftRetkowitz2006, author = {Kraft, Bodo and Retkowitz, Daniel}, title = {Rule-Dependencies for Visual Knowledge Specification in Conceptual Design}, year = {2006}, abstract = {In: Proc. of the 11th Intl. Conf. on Computing in Civil and Building Engineering (ICCCBE-XI) ed. Hugues Rivard, Montreal, Canada, Seite 1-12, ACSE (CD-ROM), 2006 Currently, the conceptual design phase is not adequately supported by any CAD tool. Neither the support while elaborating conceptual sketches, nor the automatic proof of correctness with respect to effective restrictions is currently provided by any commercial tool. To enable domain experts to store the common as well as their personal domain knowledge, we develop a visual language for knowledge formalization. In this paper, a major extension to the already existing concepts is introduced. The possibility to define rule dependencies extends the expressiveness of the knowledge definition language and contributes to the usability of our approach.}, subject = {CAD}, language = {en} } @inproceedings{PoghossianSchumacherKloocketal.2006, author = {Poghossian, Arshak and Schumacher, Kerstin and Kloock, Joachim P. and Rosenkranz, Christian and Schultze, Joachim W. and M{\"u}ller-Veggian, Mattea and Sch{\"o}ning, Michael Josef}, title = {Functional testing and characterisation of ISFETs on wafer level by means of a micro-droplet cell}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:a96-opus-1259}, year = {2006}, abstract = {A wafer-level functionality testing and characterisation system for ISFETs (ionsensitive field-effect transistor) is realised by means of integration of a specifically designed capillary electrochemical micro-droplet cell into a commercial wafer prober-station. The developed system allows the identification and selection of "good" ISFETs at the earliest stage and to avoid expensive bonding, encapsulation and packaging processes for nonfunctioning ISFETs and thus, to decrease costs, which are wasted for bad dies. The developed system is also feasible for wafer-level characterisation of ISFETs in terms of sensitivity, hysteresis and response time. Additionally, the system might be also utilised for wafer-level testing of further electrochemical sensors.}, subject = {Biosensor}, language = {en} }