Wyniki wyszukiwania - Biblioteka Nauki

1

Poles and zeros assignment by state feedbacks in positive linear systems

100%

Kaczorek T.

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tom Vol. 31, No. 3

593--605

EN

Poles and zeros assignment problem by state feedbacks in positive continuous-time and discrete-time systems is analyzed. It is shown that in multi-input multi-output positive linear systems by state feedbacks the poles and zeros of the transfer matrices can be assigned in the desired positions. In the positive continuous-time linear systems the feedback gain matrix can be chosen as a monomial matrix so that the poles and zeros of the transfer matrices have the desired values if the input matrix B is monomial. In the positive discrete-time linear systems to solve the problem the matrix B can be chosen monomial if and only if in every row and every column of the n × n system matrix A the sum of n−1 its entries is less than one.

2

Characteristic polynomials of positive and minimal-phase electrical circuits

100%

Kaczorek T.

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tom R. 92, nr 6

79--85

EN

Characteristic polynomials of positive and minimal-phase electrical circuits are addressed. It is shown that the characteristic polynomials of the electrical circuits are independent of the choice of their reference mesh and of their reference node. Conditions are established under which the positive electrical circuits have real eigenvalues and are minimal-phase linear systems. Sufficient conditions for cancelation of zeros and poles of minimal-phase electrical circuits are given.

PL

W pracy wykazano, że wielomiany charakterystyczne obwodów elektrycznych są niezależne od wyboru oczka odniesienia w metodzie oczkowej i węzła odniesienia w metodzie węzłowej analizy tych obwodów. Podano warunki przy spełnieniu których dodatnie obwody elektryczne mają rzeczywiste wartości własne i są minimalnofazowymi obwodami elektrycznymi. Podano również warunki wystarczające skracania zer i biegunów w minimalnofazowych obwodach elektrycznych. Rozważania zostały zilustrowane przykładami dodatnich i minimalnofazowych obwodów elektrycznych.

3

Konstrukcje i wyposażenie rozdzielnic niskiego napięcia w Polsce

100%

Batura R. , Olszewski S.

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tom R. 89, nr 2

8--14

PL

Artykuł ma charakter przeglądowy, z elementami historycznymi, jest związany z konstrukcją i wyposażeniem eksploatowanych i oferowanych w Polsce rozdzielnic niskiego napięcia. Przedstawiono rozdzielnice niskiego napięcia stosowane w dystrybucji oraz rozdziale energii elektrycznej u odbiorców komunalnych i przemysłowych.

EN

The article an overview with historical elements related to the design and equipment of low voltage switchboards operated and offered in Poland. Presented low voltage switchboards used in the distribution and distribution electrical energy in municipal and industrial recipients.

4

Postawić kwantową teorię pola z głowy na nogi. Część I

80%

Chankowski P.

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tom T. 74, z. 3

5--14

PL

Wbrew wrażeniu jakie można odnieść z lektury większości standardowych podręczników, równania falowe Diraca, Kleina-Gordona i inne nie są podstawą relatywistycznej kwantowej teorii pola. W niniejszym artykule staram się pokazać, jak powinna być ona poprawnie formułowana i omawiam pewne jej aspekty, które na ogół nie są przedstawiane właściwie. Moim celem jest spowodowanie zmiany w nauczaniu kwantowej teorii pola. Tekst został podzielony na trzy części. W pierwszej przypominam krótko historyczny rozwój kwantowej teorii pola i omawiam jej sformułowanie jako kwantowej teorii oddziałujących cząstek (relatywistycznych lub nierelatywistycznych).

EN

Despite the impression that can be gained from most of the standard textbooks, Dirac, Klein-Gordon and other wave equations do not constitute the basis of relativistic quantum field theory. In this article I attempt to show how it should be formulated properly and discuss some of its aspects which usually are presented unsatisfactorily. My aim is to cause the change in the way quantum field theory is taught. The text is split into three parts. In the first one I briefly recall the quantum field theory historical development and present its formulation as a quantum theory of interacting particles (relativistic or nonrelativistic).

5

Morphological responses of six plant species to patchy habitat with different nitrogen concentrations using in-growth core methods

70%

Du F. , Sui Y. , Xu X. , Zhang X. , Hao W. , Shao M. , Hu L. , Shan L.

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tom Vol. 61, nr 2

257--269

EN

Soil nutrient pattern can be a functional tool for grassland restoration. In order to promote the growth of a specific or group of expected plant species, it is necessary to measure the responses of different species to nutrient – rich patches and detect the differences among them. In this article, we measured aboveground biomass and morphological traits of six species as dry weight, length, surface area, specific root length and diameter of fine roots in response to nitrogen addition patches using ingrowth core method. The six species are Artemisia scoparia, Stipa bungeana, Artemisia sacrorum, Artemisia giraldii, Lespedeza dahurica and Astragalus melilotoides. All are the dominant species in different stages of secondary succession of loess hilly region, China. Twelve individuals of each species were selected to install ingrowth cores. Six of the individuals were used as treatment group, they were treated to install with four cores of no (addition’s control), low, medium and high levels of nitrogen additions. Another six of them were used as species’ control group, the four installed cores around them had no nitrogen addition. The results showed that: 1) After 105 days in situ, for all the six species, summed dry weight, length and surface area measured in the four cores of the treatment group were significantly greater than the corresponding values in species’ control group. In aboveground biomass, however, only A. scoparia in the treatment group had significantly outweighed that in the species’ control group. 2) Irrespective of nitrogen additions levels, significant differences of length, diameter and surface area existed among the six species, which implied that species had their intrinsic species specific morphological traits. 3) In dry weight, length and surface area, the responses of all the six species to nitrogen addition levels were positive, significantly more roots were grew into the cores with higher nitrogen additions; while in specific root length, the responses were negative. 4) Perhaps the six species had a special nitrogen requirement, as interaction effects of species and addition levels in surface area were found significant. 5) The foraging precision of the six species to nutrient-rich patches had positive but insignificant correlation with root system size; there existed a significant positive correlation between the precision and the sensitivity to the designed patchy habiats. 6) Among the six species, A. scoparia, A. sacrorum and S. bungeana have higher sensitivity and precision than L. dahurica and A. melilotoides in terms of foraging the nitrogen addition cores or patches. It seems that fast growing species that dominate in early successional stage, like A. scoparia and S. bungeana in our case, obtained more benefits from nutrient patchy habitat. We advised that, in infertile lands, fertiliser be applied in a patchy way to accelerate the restoration of old fields as early as possible once they were abandoned.