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1
Content available remote A review and analysis of Quade’s fundamental geometric time domain concept for the summation of non-active powers of poly-phase systems
Riedinger Dirk
Przegląd Elektrotechniczny
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2022
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R. 98, nr 9
1--8
EN
How to determine the total non-active power of arbitrary periodical poly-phase loads or in other words: how to sum non-active powers resulting from non-sinusoidal and unbalanced voltages and currents? With algebraic summation or via aggregate power like the standards propose? In the time domain or with harmonic decomposition? What is the genuine meaning of non-active and apparent power? The reader may be amazed by questioning these problems which seem to be solved. Instead this article shows that the general solution is not that of the standards which define limiting cases but one that exists since a long time in the form of the geometric power concept of W. Quade that is commonly unkown today. The geometric method is compared to the concepts of aggregate power (Rechtleistung) and the algebraic summation of fictitious non-active powers. The consequences and meaning of the different concepts are analyzed.
PL
Jak wyznaczyć całkowitą moc nieczynną dowolnych okresowych odbiorników wielofazowych, czyli inaczej: jak zsumować moce nieczynne wynikające z niesinusoidalnych i niezrównoważonych napięć i prądów? Z sumowaniem algebraicznym czy za pomocą sumarycznej mocy, jak proponują normy? W dziedzinie czasu czy z rozkładem harmonicznym? Jakie jest prawdziwe znaczenie nieaktywnej i pozornej mocy? Czytelnik może być zdumiony kwestionowaniem tych problemów, które wydają się być rozwiązane. Zamiast tego artykuł ten pokazuje, że generalnym rozwiązaniem nie jest rozwiązanie norm definiujących przypadki graniczne, ale takie, które istnieje od dawna w postaci koncepcji geometrycznej potęgi W. Quade, która jest dziś powszechnie nieznana. Metodę geometryczną porównuje się z pojęciami zagregowanej mocy (Rechtleistung) i algebraicznym sumowaniem fikcyjnych mocy nieczynnych. Analizowane są konsekwencje i znaczenie różnych pojęć.
2
Content available Some Ideas about Connected Graphs Isomorphism
Marchenko L., Podgornaya V.
Advances in Computer Science Research
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2018
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Nr 14
105--123
EN
In the paper we investigate the existence of graphs isomorphism and the search for invariants of connected graphs. A new graph invariant is formulated. It can be used to detect isomorphism of connected graphs. The vector space of all simple cycles of the graph and their edge-disjoint unions (cycle space) and the vector space of all cutting sets of the graph and their edge-disjoint unions (cut space) are constructed in the article for finding a new graph invariant. The authors investigate the method of constructing these vector spaces: cycle space and cut space. A new estimate of the dimensions of these vector spaces of the graph is given. The obtained invariant is demonstrated on a concrete example. A counterexample is constructed to confirm the fact that the proposed invariant can be used as a necessary but not sufficient condition for graphs isomorphism. A heuristic algorithm is proposed for constructing a one-to-one correspondence between sets of vertices of isomorphic graphs.
PL
W artykule badamy istnienie izomorfizmów między grafami oraz poszukujemy niezmienników grafów spójnych. Tworzony jest nowy niezmienniczy graf. Metoda może służyć do wykrywania izomorfizmów między grafami spójnymi. W pracy użyto pojęcia przestrzeni wektorowej wszystkich prostych cykli grafu i ich sum względem rozłącznych krawędzi oraz przestrzeni wektorowej wszystkich zbiorów grafów uciętych i ich rozłącznych krawędziowo sum. Zbadano metodę konstruowania takich przestrzeni wektorowych: przestrzeni cyklicznej i przestrzeni cięcia. Podano nowe oszacowanie wymiarów tych tego typu przestrzeni wektorowych grafów. Otrzymany niezmiennik jest pokazany na konkretnym przykładzie. W pracy podano kontrprzykład, aby potwierdzić fakt, że zaproponowany niezmiennik może być użyty jako warunek konieczny, ale niewystarczający dla izomorfizmu grafów.
3
Content available remote Comparison of three different 2-D space vector PWM algorithms and their FPGA implementations
Bishuang F., Guanzheng T., Shaosheng F.
Journal of Power Technologies
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2014
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Vol. 94, nr 3
176--189
EN
To improve the flexibility of the multilevel space vector pulse width modulation (SVPWM), various algorithms have been developed. A theoretical comparison is made for three 2-D SVPWM algorithms: they are g-h frame, α' - β' frame and multilevel SVPWM based on two-level (α* - β* frame). The aim is to provide a guideline for the selection of the most appropriate SVPWM technique for digital implementation. Among them, the α' - β' frame offers the best flexibility with the least calculation and is well suited for digital implementation. The α* - β* frame is the most intuitionistic but has the largest calculation. New general methods of the g-h frame and α' - β' frame for any level SVPWM are also provided, which needs only the angle θ and the modulation depth m to generate and arrange the final vector sequence. All three methods are implemented in a field programmable gate array (FPGA) with very high speed integrated circuit hardware description language (VHDL) and compared in terms of implementation complexity and logic resources required. Simulation results show the absolute advantages of α' - β' frame in briefness and resources use. Finally, an experimental test result is presented with a three-level neutral-point-clamped (NPC) inverter.
4
Content available Uniformly bounded set-valued composition operators in the spaces of functions of bounded variation in the sense of Schramm
Ereú T., Merentes N., Sanchez J. L., Wróbel M.
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
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2012
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Vol. 17
37-47
EN
We prove that, under some general assumptions, the one-sided regularizations of the generator of any uniformly bounded set-valued composition operator, acting in the spaces of functions of bounded variation in the sense of Schramm with nonempty bounded closed and convex values is an affine function. As a special case, we obtain an earlier result ([15]).
5
Content available Continuity of superquadratic set-valued functions
Troczka-Pawelec K.
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
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2012
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Vol. 17
77–86
EN
Let X = (X,+) be an arbitrary topological group. The aim of the paper is to prove a regularity theorem for set-valued superquadratic functions, that is solutions of the inclusion 2F(s) + 2F(t) ⊂ F(s + t) + F(s − t), s, t ∈ X, with values in a topological vector space.
6
Content available Some remarks on mappings that preserve unit distance
Billich M.
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
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2009
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Vol. 14
7-11
EN
In the present paper we investigate some properties on isometric mappings between Euclidean spaces. In addition, non-isometric distance one preserving mappings are also considered.
7
Content available remote A study of bornological properties of the space of entire functions represented by multiple Dirichlet series
Abdul-Hussein M. S., Srivastava G. S.
Fasciculi Mathematici
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2005
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Nr 35
135-150
EN
The space of entire functions represented by Dirichlet series of several complex variables has been studied by S. Dauod [1]. M.D. Patwardhan [6] studied the bornological properties of the space of entire functions represented by power series. In this work we study the bornological aspect of the space Γ of entire functions represented by Dirichlet series of several complex variables. By Γ we denote the space of all analytic functions α (s1, s2) = , having finite abscissa of convergence. We introduce bornologies on&Gamma and Γ and prove that Γ is a convex bornological vector space which is the completion of the convex bornological vector space Γ.
8
Content available remote Transformations on the product of Grassmann spaces
Havlicek H., Pankov M.
Demonstratio Mathematica
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2005
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Vol. 38, nr 3
675--688
9
Content available remote Podstawy mnogościowe wielomianów symetrycznych wielu zmiennych w notacji spektralnej : zarys teorii
Piwowarczyk T.
Czasopismo Techniczne. Elektrotechnika
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2000
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R. 97, z. 4-E
38--60
EN
All symmetric polynomials of multiple variables, with the variables belonging to the fixed, final set, are denoted by means of some abstract symbols. They are known as spectral, or multipower symbols. This set is analysed from a point of view of a set theory. The article contains the definitions of those relations which are used for computing elements in numerous subsets, such as equivalence relation, ordering relation, quotient sets, combinatorics formulas. In other words, some set theory model is proposed for symmetric polynomials of multiple variables. Such a model provides a solid basis for the further study of symmetric polynomials, and first of all, for the study of their numerous vector subspaces. This study will be developed in a theoretically unlimited set of algebraic identities which are particularly useful when it comes to engineering applications
10
Content available remote Wektory i tensory
Kordecki Z.
Czasopismo Techniczne. Budownictwo
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2000
|
R. 97, z. 5-B
41--57
EN
The paper deals with problems of: - fixed and free vectors, - affine and metric spaces, - vectors of different variance, - laws of vector transformation, from two points of view: one based on geometric theory, the second based on linear algebra.
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