Wyniki wyszukiwania - Biblioteka Nauki

1

Mодуляция как переводческая трансформация

100%

Гочев (Gochev) Г. G. , Великотырновский университет им. Кирилла и Мефодия (Болгария)

Acta Universitatis Lodziensis. Folia Linguistica Rossica

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2012

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tom 08

EN

Modulation is a process which involves changing the informative parameters of the source language word. The concrete manifestation of this transformation is the act of replacing the source language words with equivalents unrelated to the systematic regularities of lexis and as such they might a) have relevance to these regularities, i.e. the equivalent exhibits a semantic or associative link with the source language word, or b) not have relevance to these regularities, i.e. the equivalent does not exhibit a semantic or associative link with the source language word, but its use is justified by extralinguistic factors (e.g. logical reasoning or a concrete situation).

2

Point spread function in a confocal microscope with trigonometric pupil filters.

100%

Magiera A.

Optica Applicata

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2000

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tom Vol. 30, nr 2-3

455-461

EN

The distribution of point spread function was examined versus the spatial frequencies of the filters of cos(Np) type modulating the aperture of the confocal CSM for different values of numerical aperture. In particular, the following relations were determined: (i) PSF as dependent on the pupil modulating spatial frequency r for N=1, 2, 3, 4, 5, 6, 7, 9, 11 and numerical aperture NA=0.8; (ii) PSF for filters of cos(4 rho ), cos(10 rho ) type and NA=0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4; (iii) cut-off spatial frequencies r/sub c/ for the aperture modulated by cos(N rho ) for N=0,..., 20, NA=0.2, 0.5, 1.0 and lambda =0.6328 mu m.

3

Trends in Adaptive Modulation and Coding

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Zalonis A. , Miliou N. , Dagres I. , Polydoros A. , Bogucka H.

Advances in Electronics and Telecommunications

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2010

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tom Vol. 1, no. 1

104--111

EN

This paper presents a review of techniques proposed in the literature that target the best use of resources available in a wireless communication system. These are referred to as Adaptive Modulation and Coding (AMC) techniques. A brief overview of fundamental communication limits, in particular channel capacity, is also provided in order to establish the limits for any adaptation algorithm. Furthermore, an appropriately chosen example is presented in order to demonstrate the usefulness of accurate performance modeling in the AMC design. Finally, challenges and future problems are mentioned.

4

Modified Topology and Modulation Technique for Z-Source Neutral-Point Clamped Inverter

100%

Akbari E. , Zishan F.

Power Electronics and Drives

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2022

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tom Vol. 7 (42)

210--226

EN

The impedance network makes it possible to increase and decrease the voltage, which is not available in normal inverters (voltage and current sources).This paper presents a modified topology and modulation technique for a three-phase Modified Z-Source Neutral-Point Clamped (MZS-NPC) inverter. A modulation scheme for the proposed topology is designed based on maximum gain control method to achieve the maximum voltage gain by simple implementation and balancing the neutral point voltage of the dc link. In order to supply the desired voltage to the critical load in an islanded micro-grid, a closed-loop ac voltage controller is realized in fuel cell or photovoltaic applications based on the proposed inverter. The ability to reinforce and validity of topology operations and modulation techniques has been demonstrated by simulation. It should be noted that the simulations are implemented in MATLAB / Simulink software.

5

Demodulation of non-stationary machine vibration using cycle-time scale

100%

Krzyworzeka P. , Cioch W.

Archives of Acoustics

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2006

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tom Vol. 31, No. 2

167-177

EN

Inner time-scale affects the operation of angle demodulator. Can linear approximation of monotonic variations in carrier-cycle improve the recovery of unknown low-energy signal modulating observable vibration processes? Authors make an attempt to answer using phase-locked loop PLL as demodulator. Simulations conducted for complex phase model indicate potentially vast possibilities of recognizing and selection of information component. Appropriate selection of approximation time-range enables to achieve acceptable RMS value loads and harmonics of rotational speed of outgoing estimates.

6

Synteza sygnału wysokiej częstotliwości przez podwójną modulację

100%

Tarnowski S.

Mikroelektronika i Informatyka : prace naukowe

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2007

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tom Z. nr 7

139-142

PL

Generacja sygnału wysokiej częstotliwości jest trudnym problemem ze względu na ograniczoną maksymalną częstotliwość pracy obwodów półprzewodnikowych. zastosowanie do tego celu specjalistycznych układów półprzewodnikowych wysokiej częstotliwości , nie zawsze jest uzasadnione ekonomicznie. Poniższy artykuł prezentuje możliwość wykorzystania analogowych mieszaczy częstotliwości do generowania sygnału tylko na podstawie częstotliwości referencyjnej. Do generownia sygnłu sterujacego wykorzystane sa dwa przetworniki cyfrowo-analogowe i dwa mieszacza częstotliwości. Zastosowanie dwóch mieszaczy powodują kompensację szumów fazowych wnoszonych przez układy przetworników cyfrowo-analogowych wykorzystanych w projekcie.

7

The Diagnostic Of Technical Condition Of Turbine Engine's Bearing By Means Of Method Of Alternator Frequency Modulation

88%

Gębura A. , Tokarski T.

Journal of Polish CIMAC

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2007

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tom Vol. 2, no 2

123-131

EN

The paper has been intended to discuss an application of a diagnostic method based on measurements and analyses of frequency modulation. The method has been developed at Instytut Techniczny Wojsk Lotniczych – ITWL (Air Force Institute of Technology, Warszawa, Poland). It has been based on measurements of pulse-frequency modulation of a DC generator or that of an AC alternator. The method has been intended to determine the usual wear-and-tear of a subassembly under examination and to locate defects, both of them in the course of normal operation of an aircraft power plant. The diagnostic system is connected to any terminal supplied with DC or AC voltage. Results of performance tests of the turbine engine have been presented. An airborne D.C. generator and a threephase rate A.C. alternator were used as generators-observers. Subsequent stages of the wear-and-tear of rolling bearings, the turbine unbalance, and the misalignment were observed while taking measurements during both flight and bench tests. What was observed first was some increase in the amplitude of braking the bearing induced by the increasing resistance to motion due to the wear-and-tear of the bearing’s components. Then, the amplitude was observed to decrease due to the wearing-in of the bearing’s components. At the beginning of operation, the rolling-friction coefficient was 0.4, then this value kept increasing with time until some rapid decrease beyond any mathematical meaning. This decrease resulted from the extension of radial clearances. Such being the case, the bearing’s operation had to be stopped to avoid intense destructive effects.

8

Evaluation of potential dangers of Mobile Telecommunication frequencies and modulations

88%

Bamisaye A. J.

Journal of Telecommunications and Information Technology

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2013

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tom nr 2

30--34

EN

Mobile Telecommunication is one of the fastest growing technologies in the world. The effects of its high frequencies and complex modulations to the exposed population are considered in this paper. Experimental studies examining a variety of effects on all levels of the organism, ranging from effects on single cells to effects which manifest themselves as reactions of the entire body, there have been a number of epidemiological studies in order to establish the possible causal correlations between higher exposures to HF EMFs. Recommendations on the reduction of the effects of EMFs of Mobile Telecommunication on humans was presented.

9

Efficiency comparison between the LLCL and LCL-filters based single-phase grid-tied inverters

88%

Wu W. , Huang M. , Blaabjerg F.

Archives of Electrical Engineering

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2014

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tom Vol. 63, nr 1

63-79

EN

An LLCL-filter is becoming more attractive than an LCL-filter as the interface between the grid-tied inverter and the grid due to possibility of reducing the copper and the magnetic materials. The efficiency of the LLCL-filter based single-phase grid-tied inverter also excites interests for many applications. The operation of the switches of the VSI is various with different modulation methods, which lead to different efficiencies for such a single-phase grid-tied inverter system, and therefore important research has been carried out on the effect of the choice of PWM schemes. Then power losses and efficiencies of the LLCL-filter and the LCL-filter based single-phase grid-tied inverters are analyzed and compared under the discontinuous unipolar, the dual-buck and the bipolar modulations. Results show that the efficiency of LLCL-filter based inverter system is higher than the LCL- filter based independent on the modulation method adopted. Experiments on a 2 kW prototype are in good agreement with results of the theoretical analysis.

10

Theoretical model of thermodetection system.

88%

Dulski R. , Madura H. , Niedziela T. , Sikorski Z.

Optica Applicata

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2000

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tom Vol. 30, nr 2-3

443-453

EN

A theoretical model of thermodetection system based on the linear filter theory is proposed. The modulation transfer function of a thermodetection system is expressed as a product of the modulation transfer functions of its subsystems. A numerical technique for computing the optical transfer function of an objective based on the wave optics is proposed, which takes into account spectral characteristics of the imaging chain. Infrared images obtained with the model simulate well the experimentally obtained images.

11

Badanie 27-poziomowego falownika kaskadowego

88%

Wiatr P.

Przegląd Elektrotechniczny

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2012

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tom R. 88, nr 11a

43-46

PL

Artykuł przedstawia topologię 27-poziomowego przekształtnika kaskadowego. W ramach pracy opisano sposób modulacji przekształtnika. Przedstawiono wyniki badań symulacyjnych i laboratoryjnych oraz podsumowano zalety i wady badanej topologii.

EN

This article presents a 27-level cascaded converter topology. Within this paper a modulation strategy and results of simulation as well as laboratory model verification has been presented. Finally, the article summarizes advantages and disadvantages of the studied topology.

12

Resource allocation in MIMO systems specific to radio communication

88%

Ghaderi B. , Parhizgar N.

Archives of Electrical Engineering

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2019

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tom Vol. 68, nr 1

91--100

EN

The performance of the multi-input multi-output (MIMO) systems can be improved by spatial modulation. By using spatial modulation, the transmitter can select the best transmit antenna based on the channel variations using channel state information (CSI). Also, the modulation helps the transmitter to select the best modulation level such that the system has the best performance in all situations. Hence, in this paper, two issues are considered including spatial modulation and information modulation selection. For the spatial modulation, an optimal solution for obtaining the probability of selecting antenna is calculated and then Huffman coding is used such that the transmitter can select the best transmit antenna to maximize the channel capacity. For the information modulation, a multi quadrature amplitude modulation (MQAM) strategy is used. In this modulation, the modulation size is changed based on the channel state variations; therefore, the best modulation index is used for transmitting data in all channel situations. In simulation results, the optimal method is compared with Huffman mapping. In addition, the effect of modulation on channel capacity and a bit error rate (BER) is shown.

13

An on-line phase measuring profilometry based on modulation

88%

Wu Y. , Cao Y. , Lu M. , Li K.

Optica Applicata

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2012

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tom Vol. 42, nr 1

31-41

EN

An on-line phase measuring profilometry (PMP) based on Stoilov's algorithm which can be used for on-line 3-D shape inspection is proposed in this paper. A stationary sinusoidal grayscale fringe pattern is projected onto the object kept on the production line, and an immobile charge-coupled device (CCD) is used to capture five deformed patterns equidistantly. The phase distribution is calculated by using Stoilov's algorithm, and the height distribution of the inspected object is obtained through the relation of phase-height mapping. When inspected object moves, the positions of images in different deformed patterns change, so the pixel matching is implemented to acquire the equivalent phase-shifting which meets the requirement of Stoilov's algorithm. Modulation which represents the contour of inspected object is used as the template to perform the pixel matching for the first time in this paper. Computer simulation and experiment verified the effectiveness of the method.

14

Assessment of Hand Function Through the Coordination of Contact Forces in Manipulation Tasks

88%

Jaric S. , Uygur M.

Journal of Human Kinetics

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2013

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tom 36

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nr 1

5-160

EN

Exploration of force coordination has been one of the most often used approaches in studies of hand function. When holding and manipulating a hand-held object healthy individuals are typically able to highly coordinate the perpendicular (grip force; GF) with the tangential component of the contact force (load force; LF). The purpose of this review is to present the findings of our recent studies of GF-LF coordination. Regarding the mechanical factors affecting GF-LF coordination, our data suggest that both different hand segments and their particular skin areas could have markedly different friction properties. It also appears that the absolute, rather than relative safety margin (i.e., how much the actual GF exceeds the minimum value that prevents slipping) should be a variable of choice when assessing the applied magnitude of GF. The safety margin could also be lower in static than in free holding tasks. Regarding the involved neural factors, the data suggest that the increased frequency, rather than an increased range of a cyclic LF could have a prominent detrimental effect on the GF-LF coordination. Finally, it appears that the given instructions (e.g., 'to hold' vs. 'to pull') can prominently alter GF-LF coordination in otherwise identical manipulation tasks. Conversely, the effects of handedness could be relatively week showing only slight lagging of GF in the non-dominant, but not in the dominant hand. The presented findings reveal important aspects of hand function as seen through GF-LF coordination. Specifically, the use of specific hand areas for grasping, calculation of particular safety margins, the role of LF frequency (but not of LF range) and the effects of given instructions should be all taken into account when conducting future studies of manipulation tasks, standardizing their procedures and designing routine clinical tests of hand function.

15

Diversity and Multiplexing Techniques of 802.11n WLAN

88%

Krasicki M.

Advances in Electronics and Telecommunications

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2010

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tom Vol. 1, no. 2

12--16

EN

This paper is devoted to analyze an improvement in the performance of WLAN (Wireless Local Area Network) systems introduced by space and space-time diversity, as well as spatial multiplexing. These MIMO (Multiple-Input Multiple-Output) techniques are approved in the latest 802.11n specification. In order to perform the experiment, a Matlab application that simulates WLAN physical layer has been developed.

16

Modulation of the avian immune system: suppression versus induction of immunity

88%

Rautenschlein S. , Neumann U.

Polish Journal of Veterinary Sciences

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2004

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tom 07

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nr 1

17

Efficiency comparison between the LLCL and LCL-filters based single-phase grid-tied inverters

75%

Wu W. , Huang M. , Blaabjerg F.

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nr 1

18

Modulation of murine macrophages and T lymphocytes by lysozyme dimer

75%

Obminska-Mrukowicz B. , Szczypka M. , Gaweda B.

Polish Journal of Veterinary Sciences

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2002

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tom 05

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nr 4

EN

The effects of lysozyme dimer (2 and 20 μg/kg) administered i.p. once and four times to mice on the phagocytic and killing ability of peritoneal macrophages, interleukin-1 (IL-1) production by murine macrophages stimulated in vitro with lipopolisaccharide of E. coli and expression of thymocyte, splenocyte and mesenteric lymphonode cell CD3+, CD4+ and CD8+ markers were studied. It was found that lysozyme dimer administered once or four times at doses of 2 (μg/kg and 20 μg/kg augments the phagocytic and killing activity of peritoneal macrophages. The strongest stimulating effect was noted after four injections of lysozyme dimer at a dose of 20 μg/kg. Moreover, lysozyme dimer is able to modulate the production of IL-1 by murine macrophages stimulated in vitro with LPS. Exposure to four doses of lysozyme dimer (20 μg/kg) enhances the synthesis and release of IL-1, but this drug administered once (2 μg/kg and 20 μg/kg) or four times (2 μg/kg) decreases IL-1 production by peritoneal macrophages. It was also found that administration of lysozyme dimer at a dose of 20 μg/kg, irrespective of the number of doses applied, increases the percentage of CD4+ thymocytes and splenocytes. Moreover, exposure to four doses of lysozyme dimer (2 and 20 μg/kg) increases the percentage of CD4+ and CD8+ mesenteric lymphonode cells.

19

Contextualism, Pragmatics and Definite Descriptions

75%

Vignolo M.

Lodz Papers in Pragmatics

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2011

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tom 7

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nr 2

291-307

EN

Very few philosophers and linguists doubt that definite descriptions have attributive uses and referential uses. The point of disagreement concerns whether the difference in uses is grounded on a difference in meaning. The Ambiguity Theory holds while the Implicature Theory denies that definite descriptions are ambiguous expressions, having an attributive meaning and a referential meaning. Contextualists have attempted to steer between the Ambiguity Theory and the Implicature Theory. I claim that the early contextualist account provided by Recanati and Bezuidehnout based on the idea that definite descriptions are semantically underdetermined and in need of a completion from the contextually available information through an optional top-down pragmatic process suffers from an explanatory gap.

20

Stany awaryjne i obserwacja napięć na kondensatorach komórek przekształtnika wielokomórkowego DC/DC

75%

Stala R.

Przegląd Elektrotechniczny

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2005

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tom R. 81, nr 9

16-24

PL

W pracy przedstawiono analizę stanów awaryjnych oraz wpływ niedokładnego generowania sygnałów sterujących na stan przekształtnika wielokomórkowego z obwodem balansującym. Podział napięcia źródła dla wielopoziomowej modulacji napięcia wyjściowego w przekształtniku wielokomórkowym realizują kondensatory naładowane do odpowiednich wartości napięć. Zaburzenie proporcji pomiędzy napięciami na poszczególnych kondensatorach komórek powoduje zwiększenie wartości maksymalnej napięcia na łącznikach powyżej wartości projektowanej oraz uniemożliwia prawidłową modulację napięcia wyjściowego. Szeregowy układ RLC (obwód balansujący), o odpowiednio dobranej częstotliwości rezonansowej, dołączony równolegle z odbiornikiem zapewnia stabilizację napięć na kondensatorach przekształtnika bez konieczności dodatkowego sterowania i pomiarów napięć. W stanie nieprawidłowej proporcji napięć źródeł w układzie, w prądzie obwodu balansującego występuje składowa o częstotliwości impulsowania pojedynczej komórki, która wywołuje zmianę napięć na kondensatorach komórek. Przedstawiono model matematyczny przekształtnika wykorzystywany do odtwarzania w czasie rzeczywistym napięć na kondensatorach wewnętrznych przekształtnika. Pomiar prądu układu balansującego i prądu odbiornika oraz wykorzystanie sygnałów sterujących pozwala na odtworzenie przebiegów napięć kondensatorów komórek i rozpoznanie stanów awaryjnych przekształtnika. W wyniku wystąpienia błędów statycznych przy generowaniu impulsów sterujących w przekształtniku może wystąpić stan ustalony z nieprawidłowym podziałem napięć na kondensatorach wewnętrznych. Jest to przypadek, w którym pomimo nieprawidłowego podziału napięć na kondensatorach przekształtnika w prądzie balansującym nie występuje składowa o częstotliwości impulsowania pojedynczej komórki, ponieważ składowa o tej częstotliwości nie występuje w napięciu wyjściowym. Dla niektórych rodzajów stanów awaryjnych przedstawiono propozycje sterowania umożliwiającego pracę układu przez eliminację uszkodzonej komórki.

EN

The paper presents an analysis of dangerous phenomenon caused by imprecise control or damage of dc/dc multicell converter with balancing circuit. For multilevel modulation the multicell converter uses charged to proper values capacitors placed in every cell. An improper relation between voltages of cells' capacitors (unbalance state) causes switches voltages increase above their rate value and also makes impossible for proper output voltage modulation. To eliminate the unbalance state the RLC series circuit (balancing circuit) of proper selected resonance frequency is connected to load in parallel. No additional control or measurements are necessary for the unbalance elimination. Under the unbalance a component about single cell's switching frequency appears in balancing circuit current. The current of this frequency affects an average cells' capacitors voltage and eliminates the unbalance. Mathematical model of the converter used for observation of voltages on cells' capacitors is presented. The output current measurements and control signals using makes possible to observation of the cells' capacitors voltages for detection of failure states of the converter. When static errors in control signals appear the converter in steady state has improper cells' voltages relation. In this case the component of single cell switching frequency does not exist in the balancing current because this frequency component does not exists in the output voltage. For some cases of failure states a special control that eliminates the failure cell and thus enables continuation of the converter operation is presented.