Tabu-search for the multi-mode job-shop problem

In a multi-processor-tasks job-shop problem (MPTJSP) there is a machine set associated with each operation. All machines are needed for the whole processing period to process the operation. The objective is to find a schedule which minimizes the makespan. In a multi-mode job-shop problem (MMJSP) there is a set of machine sets associated with each operation. One has to assign a machine set to each operation and to solve the resulting MPTJSP such that the resulting makespan is minimized. For the MMJSP a tabu-search algorithm is presented. Computational results are reported.Supported by the Deutsche Forschungsgemeinschaft, Project Br389/15-1     

The response of a streamer tube sampling calorimeter to electrons

We have constructed a simple modular electromagnetic calorimeter with 0.8X₀ copper absorbers using gas sampling with streamer tubes. To suppress saturation effects we use small cell streamer tubes (6 mm × 6 mm) filled with pure isobutane. The calorimeter has been tested with electrons in the energy range from 1 to 6 GeV. In this range the instrument shows a linear response. The energy resolution from pad and wire signals amounts to $\text{σ ≈}\text{20\%}\text{√E}$. The longitudinal shower profiles are in reasonable agreement with expectations from standard shower calculations.     

Beiträge zur galvanisierung von polymeren, 11. Metallisierung von mischungen aus epoxidharzen und acrylnitril-butadien-copolymeren

The metallization of mixtures containing epoxy resins and acrylonitrile-butadiene copolymers depends on taking the suitable ratio of components and on the hardener, which was brought to reaction with the epoxy prepolymer in presence of the copolymer. Using triethylenetetramine as curing agent the highest values of peel strength have been reached and have been increased up to 150 N/25 mm by short-time-treatment with ozone. Longer ozonization times lead to lower values of peel strength and impairment of the material. Caverns occur only in mixtures which are rich on epoxy resin, and increase in size with increasing time of ozone treatment. These samples have relatively low values of peel strength.     

Pattern evocation and geometric phases in mechanical systems with symmetry

This paper is concerned with the relation between the dynamics of a given Hamiltonian system with a given symmetry group and its reduced dynamics. We illustrate the process of visualization of reduced orbits using the double spherical pendulum. In this process of visualization, one sees certain patterns when the dynamics is viewed relative to rotating frames with certain critical angular velocities. By using the reduced dynamics, we also explain these patterns. We show that if the motion on the phase space reduced by a continuous symmetry group at a given momentum level is periodic, then there is a uniformly rotating frame, that is, a one-parameter group motion, relative to which the unreduced trajectory is periodic with the same period. If the continuous symmetry group of the system is Abelian, which corresponds to the system having cyclic variables, we derive an explicit expression for the required angular velocity in terms of the dynamic phase (an average of the mechanical connection) and the geometric phase (the holonomy of the mechanical connection). We show that one can also find such a frame if the reduced orbit is quasi-periodic and a KAM (Kolmogorov-Arnold-Moser) condition is satisfied The almost periodic case is also discussed. An important aspect of this procedure is how to use it in the presence of discrete symmetries. We show that, under appropriate conditions, the visualized orbit has, relative to a suitable uniformly rotating frame, the same temporal behavior and discrete symmetries as the reduced orbit. Since these spatio-temporal patterns are not apparent with repect to most frames, we call the phenomenon pattern evocation     

Reliability indicators

This is a review paper. It describes the state-of-the-art of the research on reliability indicators for either electronic or mechanical components. Typical component failure patterns are presented and discussed. The concept of component screening using reliability indicators is then outlined. The paper sketches a theoretical approach to the problem of detecting flaws in components. The approach is based on an old concept of energy imbalance in flawed objects.     

Comparison of kernel estimators,perceptrons and radial-basis functions for OCR and speech classification

We compare kernel estimators, single and multi-layered perceptrons and radial-basis functions for the problems of classification of handwritten digits and speech phonemes. By taking two different applications and employing many techniques, we report here a two-dimensional study whereby a domain-independent assessment of these learning methods can be possible. We consider a feed-forward network with one hidden layer. As examples of the local methods, we use kernel estimators like k-nearest neighbour (k-nn), Parzen windows, generalised k-nn, and Grow and Learn (Condensed Nearest Neighbour). We have also considered fuzzy k-nn due to its similarity. As distributed networks, we use linear perceptron, pairwise separating linear perceptron and multi-layer perceptrons with sigmoidal hidden units. We also tested the radial-basis function network, which is a combination of local and distributed networks. Four criteria are taken for comparison: correct classification of the test set; network size; learning time; and the operational complexity. We found that perceptrons, when the architecture is suitable, generalise better than local, memory-based kernel estimators, but require a longer training and more precise computation. Local networks are simple, leant very quickly and acceptably, but use more memory.