G.I. Koshovy
M. Ye. Zhukovski National Aerospace University
17, Tchkalov Str., Kharkiv, 61070, Ukraine
Surface Currents Induced by an E-Polarized Wave on Curvilinear Strips

The problem of scattering of an E-polarized electromagnetic wave by a cylindrical strip which cross-section is an arc of a smooth curve, has been reduced to a singular first-kind integral equation in reference to the surface current density. The obtained equation is convenient both to apply the mechanical quadrature method and to transform this equation into a second-kind equation by the regularization method. A wide class of arcs is studied. The class includes both parabolic arcs and quite compound arcs which have many extreme points. Besides a general dynamic model of the problem, a quasi-static model is proposed. This model admits a simple explicit solution. Numerical calculation and comparison of the results are given.

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L. Marti-Lopez1, J. Bouza-Dominguez2, R. A. Martinez-Celorio3 and J. C. Hebden4
1 AIDO, Nicolas Copernico 7 - 13, Parque Tecnologico de Valencia, C. P. 46980, Valencia, Espana.
2 Centro de Neurociencias de Cuba, A. P. 6880, C. P. 10600, La Habana, Cuba.
3 FIMEE, Universidad de Guanajuato, C. P. 37000, Salamanca, Guanajuato, Mexico.
4 Dept. of Medical Physics & Bioengineering, UCL, Malet Place Engineering Building, London WC1E 6BT, UK.
Validation of Radiative Transfer Equations for Media with Variable Refractive Index

The radiative transfer equation (RTE) and four RTEs for media with spatially varying refractive index (RTEvri) are evaluated by using them to derive the inverse square law for irradiance and the law of the ratio of irradiances at two points of a ray. Only one of the four equations yields these laws.

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Yu.B. Nechayev and R.A. Kretov

Cavity-Based Band Pass Filters

The high-parameter long-life band pass filters on the basis of cavities are developed. The filters meet the requirements set by practically all radio systems.

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K.A. Lukin and P.P. Maksymov
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkov 61085, Ukraine
Method of Calculation of Avalanche p-n Junction in Self-Excited Mode

The method of finite differences for calculation of avalanche p-n junctions in self-excited oscillation mode is proposed. It is demonstrated that the solution for nonlinear equations set of drift-diffusion model of p-n junctions found with the help of this method is satisfying the boundary conditions at mobile boundaries of the depletion region and the continuity conditions at the boundary of separation of p- and n-regions. The results of calculation of density of charges, electrical field and electrical potential of GaAs avalanche p-n junctions are given.

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A.N. Rudyakova and V.G. Kryzhanovskii
Donetsk National University
24, Universitetskaja Str., Donetsk, 83055, Ukraine
High-Efficiency Polyharmonic Fifth-Harmonic Peaking Power Amplifier

We propose to use two-period PBG-structures having U-shaped holes in a grounding plate of a microstrip line in order to obtain optimum amplitude-phase relationships of higher harmonics in the microwave-frequency polyharmonic power amplifiers. The two-period structures under consideration have better characteristics in comparison with one-period versions in both passband and stopband. Theoretical and experimental study of three versions of PBG-structures having square, rectangular and U-shaped holes, has been carried out. The result of this study demonstrate the potential of two-period PBG-structures to design output filters of amplifiers with checking of harmonics up to the fifth and higher ones.

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A.Ya. Kirichenko, E.V. Krivenko, and V.I. Lutsenko
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine
12, Academician Proskura Str., Kharkiv 61085, Ukraine
Investigation of Dielectric Characteristics of Binary Solutions by Means of Self-Excited Gunn-Effect Oscillator Stabilized by Partly Shielded Quasi-Optical Dielectric Resonator

Q-factors of natural oscillations of partly shielded half-disk dielectric resonator have been investigated. We have obtained dependences of the electronic frequency change slope of a self-excited Gunn-diode oscillator which is stabilized by a partly shielded quasi-optical resonator. There is a correlation between changes in frequency of autogeneration and a slope of electronic retuning with increment of the real and imaginary parts of permittivity of a substance.

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S.E. Degtyar
Institute for physics of mining processes,
National Academy of Sciences of Ukraine
72, R. Ljuksemburg Str., Donetsk, 83114, Ukraine
Nuclear Magnetic Resonance in the Coal-Methane System

It is shown that the deocclusion of methane from methane-oversaturated coal is multistage in character. This is related to different form of existence of methane in the structure of coal.

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V.V. Zavrazhin and Ye.V. Gladkaya
Institute of Physics of Rock Formation Processes, NAS of Ukraine
72, Rosa Luxembourg Str., 83114 Donetsk, Ukraine
Using of 1H NMR Spectroscopy for Forecasting of Gas and Rock Outburst Sources

As the result of performed experiments the method based on determining of intensities of wide and narrow lines in the spectrum of the coal samples, which characterize the number and the energy of hydrogen nuclei in coal, is developed using the nuclear magnetic resonance method. An integral factor determining the gas dynamic state of the coal massif in time and in space is obtained. Growing ratio of narrow line to wide line in the spectra of nuclear magnetic resonance (NMR) 1H is witnessing for getting closer to the coal and gas outburst source, which is in itself a gas dynamic event (GDE). Implementation of this method at coal-mining works demonstrated high reliability of using the methods of 1H NMR spectroscopy for forecasting the sources of outbursts.

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Angel Trevino Santoyo, Luis Nino de Rivera y Oyarzabal, Mikhail G. Shlyagin, Francisco J. Mendieta Jimenez, and Vasilli V. Spirin
National Polytechnic Institute of Mexico
Transmitted Intensity Variations in a Plastic-Clad Silica Optical Fiber by Exposing to Gasoline Octane Numbers 87 and 92 at Different Temperatures

We show in this paper the performance of transmitted light through a plastic clad (polymer) optical fiber, caused by optic fiber contact with commercial gasoline at different temperature influences. Our experimental setup is based in the methodology of the evanescent field absorption and the changes of the refractive index. The selected spectrum range studied is from 1100 to 1800 nanometers (nm) with temperature variation range from 5 to 50oC. We found the intensity transmitted increases in the 1500 to 1550 nm when the optical fiber is exposed to gasoline octane numbers 87 and 92, respectively. It is also found too that in 1200 nm the transmittance variation on the fiber due to temperature changes is negligible, compared with the hydrocarbon influence. This result let us know that 1200 nm wavelength can be used for a leak hydrocarbon sensor.

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A.Y. Borodavka, A.S. Posukhov, V.Y. Semenenko, and S.N. Stervoyedov
V. Karazin National University of Kharkiv,
4, Svoboda Sq., Kharkiv, 61077, Ukraine
Computer-Based Complex for Research of Diffusion Processes in Metals and Alloys with Radioactive Method

Development of a diffusion measurement technique in composite materials are presented. Potential of the developed method are determined and experimental results of measurements of diffusion Ni63 in monocrystal nickel and nickel-based alloys are illustrated.

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J.M. Estudillo-Ayala, R. Rojas-Laguna,J.A. Martin-Vela E. Alvarado-Mendez, J.A. Andrade Lucio, M. Trejo-Duran, M. Torres-Cisneros, and R. I. Mata-Chavez1
Facultad de Ingenieria Mecanica, Electrica y Electronica.
Universidad de Guanajuato. A.P. 215-A, 36730. Salamanca, Gto., Mexico.
1Centro de Investigaciones en Optica,
Lomas del Bosque 115, CP 37150,Leon Guanajuato.
AC Measurement by Using an Optical Fiber Sensor

In this work the implementation of a sensor of optical fiber current is reported by means of a magnetic structure. The sensing element (magnetic structure) consists of a magnet placed in the center of a plastic membrane. The variation in the intensity of the light caused by a mirror adapted to the membrane allowed to detect the changes in the presence of a magnetic field produced by an alternating current. Its changes were detected optically. We design a circuit to convert the light to equivalent in data to be process by a PC. The data are read and by means of a program in software Labview , is the equivalent of current according to the intensity of detected magnetic field.

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