Showing papers in "Facta universitatis. Series electronics and energetics in 2008"
TL;DR: In this paper, a review of multiresolution analysis and compactly ported orthogonal wavelets on Vilenkin groups is presented, where the Strang-Fix condition, the partition of unity property, the linear independence, the stability, and the orthonormality of 'integer shifts' of the corresponding refinable functions are considered.
Abstract: This paper gives a review of multiresolution analysis and compactly sup- ported orthogonal wavelets on Vilenkin groups. The Strang-Fix condition, the partition of unity property, the linear independence, the stability, and the orthonormality of 'integer shifts' of the corresponding refinable functions are considered. Necessary and sufficient conditions are given for refinable functions to generate a multiresolution analysis in the L2-spaces on Vilenkin groups. Several examples are provided to illustrate these results. .
43 citations
TL;DR: The results show that in order to achieve the best bit-error rate, not necessarily all MIMO layers have to be activated, and the number of activated layers in a multiple input multiple output (MIMO) system and theNumber of bits per symbol along with the appropriate allocation of the transmit power are jointly optimized under the constraint of a given fixed data throughput.
Abstract: Dedicated to Prof. Reiner Rockmann on occasion of his 70th birt hday Abstract: Existing bit loading and transmit power allocation techniq ues are often optimized for maintaining both a fixed transmit power and a fix ed target bit-error rate while attempting to maximize the overall data-rate. However, delay-critical real-time interactive applications, such as voice or video transmiss ion, may require a fixed data rate. In this contribution the number of activated layers in a multiple input multiple output (MIMO) system and the number of bits per symbol along with the appropriate allocation of the transmit power are jointly optimized unde r the constraint of a given fixed data throughput. Our results show that in order to achie ve the best bit-error rate, not necessarily all MIMO layers have to be activated.
31 citations
TL;DR: In this article, the definitions and properties of Gibbs derivatives on p adic field Qp, by using so-called pseudo-differential operators Tα, they find the kernel kα of Tα as well as the spectra of it.
Abstract: Recently, we reconsider continuously definitions and properties of Gibbs derivatives on p adic field Qp, by using so called pseudo-differential operators Tα, we find the kernel kα of Tα, as well as the spectra of it. Moreover, we show some applications of Tα to fractal analysis and medical science. .
8 citations
TL;DR: In this paper, the development of the theory of Gibbs differ-ential operators is discussed and some important older and more and recent results in this area are discussed. But the main focus is on the analysis of the Gibbs differential operator.
Abstract: This tutorial paper discusses the development of the theory of Gibbs differ- ential operators, and highlights some important older and more and recent results in this area.
5 citations
TL;DR: The possibility of using sliding-mode (SM) technique for an induction mo- tor drive with a class of inverters dedicated to high power, t he three-level voltage- source inverter (3LVSI), has been presented.
Abstract: The possibility of using sliding-mode (SM) technique for an induction mo- tor drive with a class of inverters dedicated to high power, t he three-level voltage- source inverter (3LVSI), has been presented. A designed control based on the pro- posed two-step design procedure is discussed; drive simulation results are shown.
4 citations
TL;DR: In electrical engineering, the Earth appears frequently as a media of con- ducting currents, and the utilities chassis are usually grounded, the lightning rods are grounded as well and sometime the Earth is applied as a return conductor.
Abstract: In electrical engineering the Earth appears frequently as a media of con- ducting currents. In order to protect humans of electrocuti ng, the utilities chassis are usually grounded, the lightning rods are grounded as well and sometime the Earth is applied as a return conductor. For that reason, it is necessa ry to investigate the Earth's behavior when it is used as a conducting media. The best way to do this investigation is to determine the current distribution within the Earth.
3 citations
TL;DR: In this paper, it was shown that the maximal operator of a subsequence of the (one-dimensional) logarithmic means of Vilenkin-Fourier series is of weak type (1, 1).
Abstract: The main aim of this paper is to prove that the maximal operator of a subsequence of the (one-dimensional) logarithmic means of Vilenkin-Fourier series is of weak type (1, 1). Moreover, we prove that the maximal operator of the logarithmic means of quadratical partial sums of double Vilenkin-Fourier series is of weak type (1, 1), provided that the supremum in the maximal operator is taken over special indices. The set of Vilenkin polynomials is dense in L1, so by the well-known density argument the logarithmic means t2n(f) converge a.e. to f for all integrable function f. .
3 citations
TL;DR: In this paper, the pointwise convergence of the Fejer means of functions on the Walsh and Vilenkin groups both in the point of view of one and two dimensional cases is discussed.
Abstract: It is a highly celebrated issue in dyadic harmonic analysis the pointwise convergence of the Fejer (or (C, 1)) means of functions on the Walsh and Vilenkin groups both in the point of view of one and two dimensional cases. We give a resume of the very recent developments concerning this matter, propose unsolved problems and throw a glance at the investigation of Vilenkin-like systems too. .
2 citations
TL;DR: Two ways to achieve integration at device level for modern embedded devices, and using service oriented gateway for "legacy" embedded systems are presented in this paper.
Abstract: This paper has pointed out the need for new technologies for integrating embedded devices in heterogeneous distributed networks, and outlines the perspec- tives opened by applaying service-oriented paradigm for re alizing interaction with embedded devices. As a foundation for interaction with embedded devices, XML and Web services have been used. Strong integration power of XML and Web ser- vices make presented framework appropriate for unique approach to all resources of embedded device regardless of applied technology. Developed Web services based middleware, provides application designers with a high level of semantic abstraction, hiding the complexity of the applied technologies. This makes presented framework suitable for use in many domains, independent of embedded devices physical real- ization or network characteristics. Two ways to achieve such integration have been presented in this paper: device level for modern embedded devices, and using service oriented gateway for "legacy" embedded systems.
2 citations
TL;DR: In this article, the authors investigated the effect of dynamic wavelength allocation (DWA) scheme implementation to the OBS node performance and found that the number of allocated wavelengths is dynamicaly adapted to the deflec ted burst traffic intensity.
Abstract: In this paper the effect of dynamic wavelength allocation (DWA) scheme implementation to the OBS node performance is investigated. We have developed the mathematical model of an OBS node in order to evaluate the burst blocking prob- ability. It is proposed to allocate a part of total wavelengt h capacity to be used by deflected bursts only. The results obtained from the model sh ow that if the number of allocated wavelengths is dynamicaly adapted to the deflec ted burst traffic intensity, the total blocking probability and deflected burst blocking probability significantly decrease. Concerning to the hardware requirements the implementation of deflection routing needs the limitted optical FDL buffer incorporatio n, to provide the deflected burst with the extra offset time. Also, control logic for bur st scheduler needs to be upgraded to perform the dynamic wavelength allocation for deflected bursts.
2 citations
TL;DR: In this article, an efficient generator voltage control method is presented for proving voltage-reactive states in transmission networks, which enables fast and sufficiently accurate definition of generator volta ges to realize the favorable voltage reactive states.
Abstract: This paper presents an efficient generator voltage control m ethod for im- provement of voltage-reactive states in transmission networks. This method enables fast and sufficiently accurate definition of generator volta ges to realize the favorable voltage-reactive states. In peak load state, this generato r voltage control is made to im- prove the economic operation, e.g. to reduce the active and r eactive power losses or to enlarge the reactive reserve of generators. In minimum load state, this voltage control is made to reduce the generator under-excitation states, or to make the favorable redis- tribution of those under-excitation states. The verificati on of method proposed is made in context of steady-state and dynamic simulation models, on the examples of realized and perspective states of Serbian transmission network, in own wide environment.
TL;DR: In this paper, the complete product of the symmetric group on 3 elements was studied. But the main difference between this non-commutative structure and the commutative case was not discussed.
Abstract: This work summarizes some statements with respect to Fourier analysis on the complete product of not necessarily commutative finite groups, achieved recently. In particular we devotes attention to a concrete case: the complete product of the symmetric group on 3 elements. The aim of this work is to emphasize the differences between this noncommutative structure and the commutative cases. .
TL;DR: In this article, it was proved that a point is a (Walsh) -Lebesgue point of a function f ∈ L(log L) d−1 if and only if it is Fejer summable.
Abstract: Lebesgue and Walsh-Lebesgue points are introduced for higher dimen- sional functions and it is proved that a.e. point is a (Walsh) -Lebesgue point of a func- tion f from the space L(log L) d−1 . Every function f ∈ L(log L) d−1 is Fejer summable
TL;DR: The paper contain brief overview of a recent progress on digital broadcasting development and main attention is given to the DVB-H standardisation and to possible services which can DVb-H offer.
Abstract: The paper contain brief overview of a recent progress on digital broadcasting development. Main attention is given to the DVB-H standardisation and to possible services which can DVB-H offer. Also the DVB-H support to the IP data casting and IPTV in general is enlightened. .
TL;DR: In this paper, the dynamics of optical solitons with dual-power law nonlinearity, in pres- ence of a stochastic perturbation term, is studied.
Abstract: The dynamics of optical solitons with dual-power law nonlinearity, in pres- ence of a stochastic perturbation term, is studied in this pa per. The soliton perturbation theory is exploited to obtain the Langevin equation by virtu e of which one can con- clude that solitons travel down the optical fiber with a fixed m ean free velocity.
TL;DR: Properties of quasi-measures on the dyadic group G and on the product group G d are considered and applications of this properties to the th eory of the unique-ness of Walsh series are discussed in this paper.
Abstract: Properties of quasi-measures on the dyadic group G and on the product group G d are considered and applications of this properties to the th eory of the unique- ness of Walsh series are discussed.
TL;DR: A new bilingual TTP mapping system is introduced and an analysis of the influence of several different factors on its phoneme accuracy is provided, including the letter to phoneme conversion task and the decision rule system for the language recognition task.
Abstract: In this paper, we address the problem of bilingual text-to-p honeme (TTP) mapping in which the phonetic transcription of isolated written words must be found. In general, in the bilingual/multilingual TTP mapping for isolated words, two process- ing steps are applied to each input word. The language of each word is first identified and then the letters of the word are translated into their pho netic transcriptions ac- cording to the recognized language. We use the multilayer perceptron (MLP) neural network for the letter to phoneme conversion task and a hybrid approach composed of a MLP and a decision rule system for the language recognition task. We introduce a new bilingual TTP mapping system and we provide an analysis of the influence of several different factors on its phoneme accuracy.
TL;DR: The convergence of the proposed practically applicable robustified recursive algorithm is established theoretically using the martingale theory, and an approximate optimal solution based on a recursive stochastic Newton-Raphson type procedure is suggested.
Abstract: The recursive stochastic algorithms for estimating the par ameters of linear discrete-time dynamic systems in the presence of disturbance uncertainty has been considered in the paper. Problems related to the constructi on of min-max optimal recursive algorithms are demonstrated. In addition, the ro bustness of the proposed al- gorithms has been addressed. Since the min-max optimal solution cannot be achieved in practice, an approximate optimal solution based on a recursive stochastic Newton- Raphson type procedure is suggested. The convergence of the proposed practically applicable robustified recursive algorithm is established theoretically using the mar- tingale theory. Both theoretical and experimental analysi s related to the practical ro- bustness of the proposed algorithm are also included.
TL;DR: In this article, a microwave applicator based on metallic cavity with a waveguide used to launch the energy from the source into the cavity is modelled using time-domain 3D TLM method enhanced with model for modelling of wire and boundaries.
Abstract: A microwave applicator based on metallic cavity with a waveguide used to launch the energy from the source into the cavity is modelled using time-domain 3-D TLM method enhanced with model for modelling of wire and boundaries. An influence of waveguide length on EM field distribution inside the cavity is analyzed, in terms of modes presence and corresponding EM field levels. .
TL;DR: Experimental results show that the coding time of H.264/AVC encoder is reduced by 35-42% through early identification of macroblocks that are likely to be skipped during the coding process and through reducing the number of candidate modes.
Abstract: This paper presents selective intra coding and early inter s kip fast mode decision algorithm for H.264/AVC and compares performance of H.264/AVC with prior standards. Video coding standard H.264/AVC provides gains in compression efficiency of up to 50% over a wide range of bit rates and video r esolutions compared to previous standards. In order to achieve this, a robust rat e-distortion optimization (RDO) technique is employed to select best coding mode and reference frame for each macroblock. Also, the original and modification test mo dels are compared for combined skip and intra prediction method in H.264/AVC encoder, when B pictures are analyzed. Experimental results show that the coding time is reduced by 35-42% through early identification of macroblocks that are likely to be skipped during the coding process and through reducing the number of candidate modes.
TL;DR: In this article, the multiple models and switching controllers are used for control of system with unmodeled dynamics and the robust asymptotic stability is proved for a given switching system.
Abstract: In this paper the multiple models and switching controllers is used for control of system with unmodeled dynamics. The analog part of the system is described by finite set of continuous models with unmodeled dynamics. As a set of controllers is used a finite set of LQ controllers with the prescribed degree of stability. Using linear matrix inequalities it is derived LQ controllers and upper bounds for index of performances. The set of upper bounds is used for creation of switching sequence. For so given switching system the robust asymptotic stability is proved. .
TL;DR: In this paper, gain and offset-compensated (GOC) modificati on a 6-order right-direct (BI) type wide bandpass switched-capacitor (SC) ladder filter is pro- posed.
Abstract: In this paper gain- and offset-compensated (GOC) modificati on of a sixth- order right-direct (BI) type wide bandpass switched-capacitor (SC) ladder filter is pro- posed. It is based on the use of simple and fast operational amplifiers (op amps) with low but precisely known and stable dc gain A. At first, the conventional integrators in the filter are replaced with GOC integrators and the unswit ched capacitors in the capacitive loops are split into two capacitors. Subsequent ly, the nominal op amps gain value A0 is taking into account in the capacitance sizing of some appropriately chosen capacitors.
TL;DR: In this article, an approximate analytical expression for the electric field in the center of the rounded vertex of the metallic cube is proposed, which is determined according to the numerical result s obtained using different numerical methods.
Abstract: In this paper, an approximate analytical expression for cal culation electric field in the centre of the rounded vertex of the metallic cube w ill be proposed. This expression is determined according to the numerical result s obtained using different numerical methods.
TL;DR: In this article, the main target is to construct a large enumerated class of non-linear coding methods, based on a discrete invertible transform called Riesz Product, which is associated to a class of Boolean invertable matrices of order m × m. The resulting encoding/decoding method is very fast and requires low memory.
Abstract: The main target of this work is to construct a large enumerated class of non- linear coding methods, based on a discrete invertible transform called Riesz Product, which is associated to a class of Boolean invertible matrices of order m × m. The particular class of matrices is uniquely determined by a couple of permutations of the first m natural numbers {1, 2, ..., m}, so for any m = 1, 2, 3, ..., we get at least (m!)2 different non-linear coding methods. The resulting encoding/decoding method is very fast and requires low memory. It can be used both as a new encryption tool or as a Boolean random generator. .
TL;DR: In this article, the modeling and optimization of a single-phase electric fur-nace transformer unit is considered, and some possi bilities for optimization of the core dimensions to diminish the maximum flux density and power losses are shown.
Abstract: In this paper the modelling and optimization of a single-phase electric fur- nace transformer unit is considered. First, the distributi on of the magnetic fluxes is analysed, using 3D finite element analysis. Then, some possi bilities for optimization of the core dimensions to diminish the maximum flux density an d the power losses are shown.
TL;DR: In this paper, a comprehensive monitoring and detection laboratory system for use in electrical driv es systems using induction machines is presented, in order to avoid undesirable operating conditions and to detect and diagnose incipient electrical faults.
Abstract: This paper focuses on developing and testing a comprehensive monitoring and detection laboratory system, for use in electrical driv es systems using Induction Machines. The article aims to provide further documentation for an advanced con- dition monitoring system including transducers, signal conditioning box and data ac- quisition device, in order to avoid undesirable operating c onditions and to detect and diagnose incipient electrical faults. Also, this paper sug gests the possibility of diag- nosing different types of failures by means of spectral anal ysis of current and voltage.
TL;DR: In this article, the authors investigate the efficiency of the two most popular computational electromagnetics approaches, fini te element method (FEM) and the method of moments based on the surface integral equation (MoM/SIE), both in the context of higher order modeling.
Abstract: We investigate the efficiency of the two most popular frequen cy-domain ap- proaches in computational electromagnetics (CEM); the fini te element method (FEM) and the method of moments based on the surface integral equation (MoM/SIE), both in the context of the higher order modeling. We compare the performances of the two approaches in two simple three-dimensional (3-D) problems with similar meshes, chosen as benchmark examples. The chosen examples demonstrate full-wave analysis of a wave-guiding structure (a closed-region problem) and a scatterer in free space (an open-region problem).