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.

Acalugaritei networks (ANs) are multidimensional evolutionary hierarchical networks. They are called hierarchical because the sets and subsets of components correspond to different ranks (levels), where: the set of “inferior” rank is the subset of rank zero (j = 0) of the set of immediately “superior” rank. The sets and subsets of components will be noted S_ij, where: i is the rank number of the set (i = 0,1,2,3); jis the rank number of the subset within the same set (j = 0,1,2, …, n). We will thus distinguish: \curr S_ij=(S_0j ⊂ S_1j⊂ S_2j⊂ S_3j). They are called evolutionary because the most comprehensive set of components is the set of evolutionary relations. They are called multidimensional because the components of the same rank can be classified according to n dimensions (n criteria: k_i where: i = 0, 1, 2,…, n). ANs are of different ranks (ANs_i, where: i = 0, 1, 2,…,n). In an AN of a certain rank, the set of fundamental components is the set of sequences of ANs of subordinated ranks.

Let p_[1,r;t] be defined by ∑n=0∞p[1,r;t](n)qn=(E1Er)t, where t is a non-zero rational number, r ≥ 1 is an integer and Er=∏n=0∞(1−qr(n+1)) for |q| < 1. The function p_[1,r;t](n) is the generalisation of the two-colour partition function p_[1,r;−1](n). In this paper, the authors prove some new congruences modulo odd prime ℓ by taking r = 5, 7, 11 and 13, and non-integral rational values of t.

Using q-series expansion/identities, the authors established general congruence modulo prime number for two-colour partition function.

In the paper, the authors study congruence properties of two-colour partition function for fractional values. The authors also give some particular cases as examples.

The partition functions for fractional value is studied in 2019 by Chan and Wang for Ramanujan's general partition function and then extended by Xia and Zhu in 2020. In 2021, Baruah and Das also proved some congruences related to fractional partition functions previously investigated by Chan and Wang. In this sequel, some congruences are proved for two-colour partitions in this paper. The results presented in the paper are original.

The calculation of quasistationary magnetic fields and electrostatic fields of several objects is presented in the paper. In the range of the magnetic fields of coils and transformer systems parallelepiped calculation regions are assumed. In the range of electrostatic fields analysis of the field in tanks of different shape storing inflammable liquids was undertaken. Fast subroutines using finite differences [FDM] to calculate the field were employed. These subroutines are based on the Fast Fourier Transform (FFT).

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.

This article attempts to examine the impact that traditional island cultural events have on tourism development in some of the West Indian (Commonwealth Caribbean) islands, how national tourist boards and hotels use these mega‐events for promotional purposes, how these cultural events are looked upon by the tourists themselves, and the possible dilution of the basic traditions and cultures of the territories if they are abused for tourist gain only.

Tourism and airtransport, although mass tourism was possible by other transports facilities, the great step forward was put with developments in airtransport.

Sequel of no. 4/83, p. 24 Not many national associations hold conventions in countries other than their own. In Northwest Europe it is unlikely that any country is a net recipient of national conventions from elsewhere in Europe. In fact, there is likely to be some small ‘leakage’ of national association conventions to destinations in the Mediterranean or further afield. However, Northwest Europe (particularly the U.K. and Ireland) receives a small number of North American association conventions. Based on the available data this may amount to some 25 large conventions yearly.