| M. Hayakawa*, K. Hattori**, A.P. Nickolaenko*** and L.M. Rabinowicz***
*The University of Electro-Communications, Chofu-city, Tokyo, Japan **Marine Biosystems Research Center, Chiba University, Chiba Japan ***A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine 12, Academician Proskura St., Kharkov 61085, Ukraine Connection between Energy of EQ Swarm and the Hurst Exponent of Random Variations of the Geomagnetic Field We present an evidence that the Hurst exponent of ULF variations of the geomagnetic field varies similarly to the energy release of the local swarm of earthquakes observed in 2000. Similarity is demonstrated between the energy release by the shocks and variations of the Hurst exponent derived for the records of the geomagnetic field. |
| M.A. Basarab and V.F. Kravchenko
V.L. Rvachev's Functions in Problems of Computerized Tomography (Review) In the survey new methods and reconstruction algorithms for solving problems of computerized tomography with the use of R-functions and atomic functions are considered. |
| E.G. Zelkin, V.F. Kravchenko, and M.A. Basarab
New Iterative Algorithms for Solving the Mixed Antenna Synthesis Problem New numerical algorithms for approximate solving mixed antenna synthesis problems with pre-given pattern and current amplitudes are proposed. |
| A.I. Luchaninov, M.A. Omarov, and D.C. Gavva
Kharkov National University of Radio Engineering and Electronics, 14, Lenin Ave, Kharkov, 61166, Ukraine TBasic and Weight Functions of the Problem of Nonlinear Surface Impedance Antenna Analysis by the Moment Method The system of non-linear integral equations describing the current distribution in the wire radiators with non-linear surface impedance is obtained. Using the moment method the given system is reduced to a harmonic balance equation system. It is shown by the example of the wire vibrator analysis, that at the stage of approximation of the unknown current distribution in linear and non-linear parts of the integral operator it is possible to use different systems of basic functions, and at the stage of transformation of initial integral equation to the harmonic balance equation it is possible to use different systems of weight functions. |
| M.A. Basarab and V.F. Kravchenko
Constructive Methods of Approximation of Entire Functions of Exponential Type with the Use of Atomic Functions Methods of the theory of functions and functional are used widely for solving the different problems of digital signal processing. Among the classical approximation tools (algebraic and trigonometric polynomials, splines), the non-classical approximation methods based on the theory of atomic functions (AF) should be mentioned. In this work, for the first time AFs are used for solving such spectral problems of approximation theory as summing the Fourier series and approximation by Levitan's polynomials. Examples of numerical realization of the proposed algorithms are presented in connection with solving the problems of an antenna synthesis. |
| V.V. Dolzhikov
Kharkov National University of Radio Engineering and Electronics, 14, Lenin Ave, Kharkov, 61166, Ukraine On Solution Stability of Problems in the Statistical Antenna Synthesis over Prescribed Field Pattern The stability of the problem solution in linear antenna statistical synthesis from a prescribed field pattern has been investigated for the case when the statistical parameters of fluctuations of an amplitude-phase distribution are given inaccurately. The stability is defined as a difference between the average value of the quadratic deviation of the really reproduced field pattern from the prescribed one and its minimum value. It is shown that the level of stability can be estimated with the help of two factors i.e. the stability factor with respect to the variance and the stability factor with respect to the correlation radius, which can essentially differ in magnitudes depending on the values of related statistical parameters which occur in realization. |
| G.I. Khlopov and A.L Teplyuk
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine 12, Academician Proskura St., Kharkov 61085, Ukraine Coaxial Fed Biconical Horn Antenna Development of an omnidirectional biconical horn antenna in E-plane and axial coax to waveguide transition is considered. Various types of transitions were studied and expressions for E-plane pattern were calculated. It was shown that such antenna has amplitude and phase distribution with separable variables, when the horn radius is essentially more than wavelength. Experimentally measured characteristics of radiation pattern are in good agreement with the calculation results. |
| A.V. Nechosa
V. Karazin National University of Kharkov, 4, Svoboda Sq., Kharkov, 61077, Ukraine An Accuracy Evaluation Strategy for Antenna Diagnostic Using Superbroadband Signals A usability of the antenna statistical theory methods is considered for securing statistical characteristics of the amplitude-phase distribution from near-field zone measurements of the pulse response. A strategy for choosing measuring conditions and requirements on response registration accuracy is suggested such that the antenna radiation pattern is reconstructed to a precision desired. |
| V.A. Petrov and S.A. Sheyko
Kharkov National University of Radio Engineering and Electronics, 14, Lenin Ave, Kharkov, 61166, Ukraine Equivalent Structure of Secondary Sources under Wave Backscattering The equivalent structures of secondary wave sources backscattered by turbulent nonuniformities of the atmosphere are considered. It is shown, that with any contribution of high turbulence spectrum components into the scattering the nonuniform medium can be presented as a set of linear grates with random parameters. |
| M. Weber, J. Vuori, and M. Vapa
University of Jyvaskyla. P.O. Box 35, 40014 University of Jyvaskyla, Finland Advertising Peer-To-Peer Networks over the Internet Most of the peer-to-peer overlay networks either provide a centralized way to join the network or rely on out-of-band methods for that purpose. None of them is satisfactory, since the first one relies on a single point which can fail, thus making the network vulnerable to failure and the second one gives no solution to the problem. This document proposes a new approach to the problem, using already existing systems such as Usenet, IRC and Web search engines to advertise the presence of an overlay network on the Internet and thus facilitate the binding of new nodes into such a network, in a fault tolerant way. |
| J. Kurhinen
University of Jyvaskyla. P.O. Box 35, 40014 University of Jyvaskyla, Finland Mobile Computing Environment The mobile computers are about to take over the computing society and users are willing to accept it. While the diffusion of mobile computing devices is fast the common knowledge about them is still quite variable. In many conversations and presentations everything that has something to do with mobility or wireless access is considered belonging mobile computing. And what is most troublesome is that all that is classified into a one group. However the mobile computing is versatile with different kind of devices, user environments and usage purposes. In this paper I will discuss some aspects of mobile computing that previously has been considered as one but should be separated into subcategories. |
| V.F. Oleynik
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine 12, Academician Proskura St., Kharkov 61085, Ukraine Dynamics of the Electromagnetic Interactions in Group of Radio-Electronic Facilities The mathematical model of a dynamic system of group of radio-electronic facilities has been suggested. The dynamic of states of electromagnetic interactions in the group of radio-electronic facilities has been analyzed at the different initial data. It has been shown that at the significantly large growth coefficients of the number of radio-electronic equipment the dynamic of interactions becomes unpredictable and it can result both in a sharp increase and decrease of interactions. |
| N.L. Biryukov, O.N. Tytarchuk, and N.R. Triska
Ukrainian Institute of Communication, Kiev, Ukraine Calculation of Frequencies of Four-Wave Mixing in the Optical C-Band Conditions are considered of arising of nonlinear products (of four-wave mixing) of 2fi-fj form in the paths of optical transmission systems with dense wavelength division multiplexing (DWDM). Expressions are presented and analyzed for combinative products and their arrangement over optical C-band. |
| I.M. Nevmerzhitsky, Yu.G. Ulyanov, I.V. Taranchenko, Yu.A. Siryk, and I.M. Loboda
Kharkov Military University Digital Moving Target Identification Using the Hartley Transformation |
| V.I. Antyufeev, I.E. Bakulin, V.N. Bykov, A.M. Grichanyuk, and T.V. Miroshnik-Bykova
Kharkov National University of Radio Engineering and Electronics, 14, Lenin Ave, Kharkov, 61166, Ukraine A Technique for Improving the Positioning Accuracy of Maximum-Correlation Radio Navigation Systems Through the Use of Decision Function Approximation Methods A correlation algorithm is suggested to improve the positioning accuracy of maximum-correlation navigation systems. The algorithm is based on an approximate representation, through the least-squares fit, of the discrete decision function near its extremum by a continuous function. The position of the extemum of this latter is used as an estimate of the shift between the current and the reference images. Results of statistical tests of the algorithm show that the estimates obtained are biased. |
| A.P. Kondratenko and A.N. Korzhov
Kharkov Military University Synthesis of Continuous Complex Interference Compensation Device for Radio Measuring Systems of Spaceborne Vehicle Control The temporal and spectral characteristics of the components of the television signal as an interfering one are briefly analyzed. The adaptive methods of protecting the reception channels of the considered complexes against unintentional interferences are shown to be worthwhile and realizable. The problem of synthesizing an anti-interference device for radio measuring systems has been solved, thereby enabling one to find a canonical structure of the interference compensation device. |