Refine
Year of publication
Institute
- Fachbereich Elektrotechnik und Informationstechnik (234)
- Fachbereich Medizintechnik und Technomathematik (212)
- Fachbereich Luft- und Raumfahrttechnik (183)
- Fachbereich Energietechnik (177)
- IfB - Institut für Bioengineering (148)
- Solar-Institut Jülich (110)
- Fachbereich Maschinenbau und Mechatronik (107)
- Fachbereich Bauingenieurwesen (75)
- Fachbereich Wirtschaftswissenschaften (55)
- ECSM European Center for Sustainable Mobility (53)
Language
- English (1170) (remove)
Document Type
- Conference Proceeding (1170) (remove)
Keywords
- Biosensor (25)
- CAD (7)
- Finite-Elemente-Methode (7)
- civil engineering (7)
- Bauingenieurwesen (6)
- Blitzschutz (6)
- Enterprise Architecture (5)
- Clusterion (4)
- Energy storage (4)
- Gamification (4)
Direct methods comprising limit and shakedown analysis is a branch of computational mechanics. It plays a significant role in mechanical and civil engineering design. The concept of direct method aims to determinate the ultimate load bearing capacity of structures beyond the elastic range. For practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and onstraints. If strength and loading are random quantities, the problem of shakedown analysis is considered as stochastic programming. This paper presents a method so called chance constrained programming, an effective method of stochastic programming, to solve shakedown analysis problem under random condition of strength. In this our investigation, the loading is deterministic, the strength is distributed as normal or lognormal variables.
Limit and shakedown theorems are exact theories of classical plasticity for the direct computation of safety factors or of the load carrying capacity under constant and varying loads. Simple versions of limit and shakedown analysis are the basis of all design codes for pressure vessels and pipings. Using Finite Element Methods more realistic modeling can be used for a more rational design. The methods can be extended to yield optimum plastic design. In this paper we present a first implementation in FE of limit and shakedown analyses for perfectly plastic material. Limit and shakedown analyses are done of a pipe–junction and a interaction diagram is calculated. The results are in good correspondence with the analytic solution we give in the appendix.
Lightning protection design of a renewable energy hybrid-system without power mains connection
(2001)
In the year 2000 a direct lightning strike to the hybridsystem without power mains connection VATALI on the Greek island Crete results in the destruction and damage of some mechanical and electrical components. The hybrid-system VATALI was not lightning protected at that time. The hardware damage costs are approx. 60,000 €. The exposed site of the hybrid-system on top of a mountain was and still is the reason for a high risk of lightning strikes. Also in the future further lightning strikes have to be taken into consideration. In the paper a fundamental lightning protection design concept for renewable energy hybrid-systems without power mains connection and protection measures against direct strikes and overvoltages are shown in detail. The design concept was realized exemplarily for the hybrid-system VATALI. The hardware costs for the protection measures were about 15,000 €. About 50% of the costs are due to protection measures against direct strikes, 50% are due to overvoltage protection. Future extensions, new installations, or modifications have to be included into the lightning protection design concept of the hybrid-system.
Light-stimulated hydrogel actuators with incorporated graphene oxide for microfluidic applications
(2015)
Leveraging Social Network Data for Analytical CRM Strategies - The Introduction of Social BI.
(2012)
The main objective of our ROS Summer School series is to introduce MA level students to program mobile robots with the Robot Operating System (ROS). ROS is a robot middleware that is used my many research institutions world-wide. Therefore, many state-of-the-art algorithms of mobile robotics are available in ROS and can be deployed very easily. As a basic robot platform we deploy a 1/10 RC cart that is wquipped with an Arduino micro-controller to control the servo motors, and an embedded PC that runs ROS. In two weeks, participants get to learn the basics of mobile robotics hands-on. We describe our teaching concepts and our curriculum and report on the learning success of our students.
RaWid was the German national technology programme on transonic aerodynamics and supporting technologies, lasting from 1995 to 1998. One of the main topics was laminar wing development. Besides aerodynamic design work, many operational aspects were investigated. A manufacturing concept was developed to be applied to operational laminar wings and empennages. It was built in a large scale manufacturing demonstrator with the aerodynamic shape of a 1,5 m section of the A320 fin nose. Tolerances in shape and roughness fulfilled all requirements. The construction can easily be adapted to varying stiffness and strength requirements. Weight and manufacturing costs are comparable to common nose designs. The mock-up to be designed in ALTTA is based on this manufacturing principle. Another critical point is contamination of suction surfaces. Several tests were performed to investigate perforated titanium suction surfaces at realistic operational conditions: - a one year flight test with a suction plate in the stagnation area of the Airbus "Beluga" - a one year test of several suction plates in a ground test near the airport - a one year test of a working suction ground test installation at all weather conditions. No critical results were found. There is no long term suction degradation visible. Icing conditions and ground de-icing fluids used on airports did not pose severe problems. Some problems detected require only respection of weak design constraints.
In IEC 61312-2 equations for the assessment of the magnetic fields inside structures due to a direct lightning strike are given. These equations are based on computer simulations for shields consisting of a single-layer steel grid of a given mesh width. Real constructions, however, contain at least two layers of reinforcement steel grids. The objective of this study was to experimentally determine the additional shielding effectiveness of a second reinforcement layer compared to a single-layer grid. To this end, simulated structures were set up in the high current laboratory. The structures consisted of cubic cages of 2 m side length with one or with two reinforcement grids, respectively. The structures were exposed to direct lightning currents representing the variety of anticipated lightning current waveforms. The magnetic fields and their derivatives at several positions inside the structure as well as the voltage between “floor” and “roof” in the center were determined for different current injection points. From these data the improvement of the shielding caused by a second reinforcement layer is derived.