Search results

In the paper the optimization procedure of a direct current motor with a hybrid excitation has been presented. The excitation system consists of a shunt field winding disposed around field pole and permanent magnet, both acting in parallel. The field distribution in motor for various magnet and field pole dimensions has been determined using finite element method. The flux linkage with the armature winding has been computed. Demagnetizing effect of armature current was taken into account. The optimal permanent magnet and the field pole dimensions, ensuring minimum total cost of purchase and work during assumed period of time were calculated. Motor characteristics e.g. rated torque, rated current, speed regulation limit were used as constraints. In worked up algorithm and computer program Carroll internal penalty function method was used. Some basic suggestions tor design of optimal hybrid excited dc motors with parallel permanent magnet and electromagnetic excitation are given.

I‐V characteristics of GaAs n‐i‐n structures are calculated by considering impact ionization of carriers. Impact ionization at reverse‐biased n‐i junction becomes a cause of steep current rise when an acceptor density in the i‐layer is high. It is shown that an optimum acceptor density exists to keep a good isolation. Photoconduction transients of GaAs n‐i‐n structures are also simulated, and are shown to be strongly affected by existence of n‐i junctions.

In the course of development of human communities towards industrially advanced societies of today, there have been changes not only in economic conditions in the majority of fields of human activity but also in the ways of providing for food, which went hand in hand with changes in living conditions. Large‐scale industrial production has brought about major changes in the way of life of the population. The development of industrial agglomerations results in a growing number of city dwellers, most of whom have no chance of producing foodstuffs of their own in kind. The distance between residential and industrial areas has been growing, the number of employed women has risen considerably. These are but a few factors affecting the way of boarding, particularly in households.

12,2 Millionen Bundesbürger sind über 60 Jahre alt. Im Jahre 2000 werden es bereits 14 Millionen sein. Kein Wunder also, dass die Senioren für viele Wirtschaftszweige immer interessanter werden. Dies gilt auch für die Tourismusbranche, die mit der wachsenden Reisefreude der älteren Generation rechnen kann. Im vorliegenden Beitrag werden ausgewählte Ergebnisse einer Studie wiedergegeben, die das Institut für Freizeit‐ und Tourismusberatung aus Ettlingen Anfang des Jahres gemacht hatte.

Economic effects are only one aspect of the total impact of tourism. For example, the development of a tourist industry in a particular country has varying repurcussions on the long term socio‐cultural, environmental and ecological development of the local community as a whole. This article examines the main non‐economic aspects of tourism in Greece.

This study aims to design a novel seasonal discrete grey model for forecasting monthly natural gas consumption by incorporating damping accumulation and time-polynomial term.

Considering the principle of new information priority and nonlinear patterns in the original series of monthly natural gas consumption, we establish a novel discrete seasonal grey model by adding the damping accumulation and time-polynomial term into the existing model. In addition, the order of damping accumulation and the coefficient of time-power term can be determined by the moth flame optimization (MFO) algorithm.

The empirical cases show that the proposed model has a better prediction performance when compared with other benchmark models, including six seasonal grey models, one statistical model and one artificial intelligent model. Based on forecasts, the proposed model can be considered a promising tool for monthly natural gas consumption (NGC) in US.

By combining the damping accumulation and the time-polynomial term, a new discrete seasonal grey model for improving the prediction performance of the existing grey model is proposed. The properties of the proposed model are given, and the newly-designed model is initially applied to predict monthly NGC in US.

The realisation of a practical generally versatile variable product assembly machine is still far from reality. However, in the same way that a generation 1 Industrial Robot can achieve high levels of versatility within certain restricted activities e. g. paint spraying ‐ spot welding etc., then by the correct choice of product and product design high levels of versatility can be achieved with assembly machines.

This article, third in a series of six, describes Life Sciences Era activities. Life sciences, rapidly gaining momentum, will begin to dominate US economic activity by 2100, then predominate well into the following century (see Figure 1). Massive advances will follow as the 140 000 genes, and 3 billion molecular units (base pairs) comprising the human genome are plotted in rough draft before 2001, and definitively charted by 2003. Once laid out, comprehending genetic patterns provides the means to govern many of the 75 trillion parts in every human.

Often, real estate factors are given much of the credit for a particular site’s success or failure when it comes to sales. The current paper asserts that some of the praise or blame heaped onto real estate decision‐makers may be undue. Sometimes success or failure is due to non‐real estate factors such as a marketing or advertising strategy, operations, or brand awareness. The paper discusses non‐real estate variables that contribute to a site’s overall success or failure, and offers diagnostics and suggestions to help address non‐real estate problems that could influence sales.

It is well known that a player in a non-cooperative game can benefit by publicly restricting his possible moves before play begins. We show that, more generally, a player may benefit by publicly committing to pay an external party an amount that is contingent on the game’s outcome. We explore what happens when external parties – who we call “game miners” – discover this fact and seek to profit from it by entering an outcome-contingent contract with the players. We analyze various structured bargaining games among such miner(s) and players that determine such an outcome-contingent contract before the start of the original game. These bargaining games include playing the players against one another as in the original game, as well as allowing the players to pay the miner(s) for exclusivity and first-mover advantage. We establish restrictions on the strategic settings in which a game miner can profit and bounds on the game miner’s profit. We also find that game miners can lead to both efficient and inefficient equilibria.