Uniform flux heat transfer in concentric laminar flow of two immiscible liquids

The energy equation was solved exactly for fully developed steady laminar flow in a circular pipe of two immncible Newton liquids with a concentric cylindrical interface between them, assuming invariant physical properties of the liquids, uniform heat flux at the wall and fully developed temperature profiles. It is shown that, even if the viscosity of the annular liquid is orders of magnitude smaller than that of the core liquid, the improvement in heat transfer to the core liquid by infection of the annular liquid cannot exceed a factor of 1 8     

Distributed generation and the voltage profile on distribution feeders during voltage dips

The presence of distributed generators in the distribution network results in an increase of the voltage magnitude close to these generators, during a fault elsewhere in the distribution system or in the transmission system. This voltage dip mitigation capability of converter-connected distributed generation (DG) units is dependent on the control strategy of the converter. To compare the influence of different types of converter-connected distributed generators on the voltage profile along distribution feeders during a fault, the quantity,“voltage ratio” is used. This voltage ratio is obtained by division of the voltage during the voltage dip by the voltage just before the voltage dip. The different converter types are modelled, and the influence on the voltage ratio is analysed.     

Themes for improved teaching of image computation

This paper reports on recommendations and results from a panel discussion and a workshop devoted to the theme of education in areas that involve image computation. One specific set of contributions is in the area of integrating image computation into required core courses such as Introduction to Computing and Data Structures. Another area of specific contributions is the development of undergraduate elective courses on topics such as robotics and medical image analysis. A third area of contributions is the improvement of traditional image processing and computer vision courses     

Bag the sags

This article describes the vulnerability of variable speed drives (VSD) to voltage sags on a theoretical basis. Then, three embedded mitigation methods are addressed in theory which protect textile processes against voltage sags, and practical measurements with a sag generator are shown. The use of embedded solutions such as kinetic buffering and boost convertor or an active front end will increase the voltage sag immunity of the process. Finally, two processes in the textile industry are described, and a brief cost-benefit analysis of the solutions is made. Experiments with a sag generator show that the voltage sag behaviour can be well described by theoretical models.     

Prof. Dr.-Ing. Dr. h. c. Franz Kollmann Zum 65. Geburtstag

Ohne Zusammenfassung     

A minimax algorithm better than alpha-beta?

An algorithm based on state space search is introduced for computing the minimax value of game trees. The new algorithm SSS1 is shown to be more efficient than α-ß in the sense that SSS1 never evaluates a node that α-ß can ignore. Moreover, for practical distributions of tip node values, SSS1 can expect to do strictly better than α-ß in terms of average number of nodes explored. In order to be more informed than α-ß, SSS1 sinks paths in parallel across the full breadth of the game tree. The penalty for maintaining these alternate search paths is a large increase in storage requirement relative to α-ß. Some execution time data is given which indicates that in some cases the tradeoff of storage for execution time may be favorable to SSS1.