In this contribution, we report on the results of analytical approaches and computer simulations of laser beam self- defocusing in laser induced plasma and gas oncoming flow above a cavity in deep penetration welding at atmospheric conditions. Nonlinear lens-like processes in oncoming jet flow ensure the feedback loop between the evaporation, penetration and laser beam intensity distribution in a workpiece. The processes are self-consistent with the conditions of the stable cavity existence. It is shown that the oncoming hot air jet flow above the plume brings the main contribution in the steady state and instability of the nonlinear beam broadening, which may reach 300%.

We name the phenomena 'optodynamics' when the light with a defined linear momentum or an angular momentum interacts with external forces and force momenta of an inertial system and there is no change in the dimensions and time of the moving system. A semiclassical theory is applied to elucidate the effects. The minimal measured angle of rotation for a laser gyro is defined. The additive decrease of the gyro scale factor due a standing wave non-plane phase front is obtained. It is found that the existence of 'dead zone' on the gyro characteristics is a result of the force momentum precession of the light in a ring resonator. Gyroscopic invariant of a ring laser is defined. Autonomous laser accelerometer is proposed.

The interaction of the slow polarized electrons and the polarized electrons of an intermediate energy with semiconductor crystal surface is considered in the present work. Natural nonuniformity of the surface potential for the crystal electrical field is taken into account. This approach made it possible to describe the fine structure of the resonance spectrum.

The effect of the new type of weak localization of electrons scattered inelastically from disordered media on Auger emission spectra is studied. This type of weak localization leads to modification of the angular spectra and energy distributions of Auger electrons. The results obtained can be applied to the determination of the characteristics of crystal surface region. It was shown that the dependence of the scattering intensity of Auger electron on an azimuthal angle is due to coherent effects. The diagram technique allows to calculate the wave function of Auger electrons more exactly. The method in question can be used for detailed description not only particle emission measurements, but also for X-ray radiation.

One of the simplest Donkin's electrostatic potentials is proved to have promising ratio 'energy dispersion -- aberration blurring' in terms of designing, on the basis of such potentials, novel charged particle spectrometers. For Donkin's potentials, clear connection is demonstrated between the above ratio and angular potential distribution.

Development of vacuum microelectronics, polarized electron sources, and flat displays renewed interest in field electron emission from semiconductors. In the report some results of mathematical modeling of this phenomenon are presented with electron escape probability calculated with 'electrical centroid rule' for 2D layer at a surface. Advantages of such approach compared to the conventional image force account are discussed for flat and nano-tip emitters. The current-voltage plots are constructed for some promising emitters.

In a simple experiment, we monitor interference effects for low energy electrons in thin magnetic Co-films as well as in a spin quantum resonator structure consisting of a Cu-film of variable thickness sandwiched between vacuum and a magnetic Co-film. In the case of the Co-film the incident electrons are unpolarized and we observe oscillations with a period of one monolayer as a function of Co-thickness when we measure the intensity of the reflected electron beam. We attribute these oscillations to the changing morphology of the Co film as a function of thickness. In the case of the sandwich structure, spin polarized electrons are injected into the resonator from the vacuum side. The Co-film provides a spin dependent reflector. Varying the resonator thickness results in periodic switching of the spin state of the specularly reflected electrons. We apply spin interferometry to study oscillatory interlayer exchange coupling and find a divergence of the coupling period predicted by theory.

We report the results on polarized electron emission from a new strained wide-gap Al_xIn_yGa_1-x-yAs/Al_zGa_{1- z}As SL with tunable position of polarization maximum. These SL's were optimized to have a minimal conduction-band offset which comes from the band line-up between the semiconductor layers of the SL. The In layer content was chosen to give minimal conduction-band offset with large strain splitting of the V-band. Simultaneous changing of Al content in both SL layers provides variation of the structure band gap. We demonstrate that tuning of the SL to the excitation energy can be achieved without loss of the electron polarization. The polarization of up to 84% was measured at room temperature.

The time-of-flight method was used to study the laser- stimulated desorption of atoms and molecules from the surface of ZnO. The kinetic energy distributions of desorbed oxygen molecules are characterized by the presence of two forms: 'fast' with kinetic temperature approximately equals 3000 K and 'slow' with T_k approximately equals 550 K. The first one is typical for desorption excitation in the self- absorption region (h(nu) > E_g), and the second one in the transparent region. Two non-thermal mechanisms of desorption are suggested.

Five elpasolite structure chlorides and bromides: Cs₂NaYCl₆, Cs₂NaLaCl₆, Cs₂NaGdCl₆, Cs₂LiLaCl₆ and Cs₂LiYBr₆ doped by Ce³⁺ ions have been investigated and results of scintillation and luminescent properties of studied crystals under optical, X- and (gamma) -ray excitation are presented. The position and splitting of Ce³⁺ 5d levels in all compounds were determined and result has a good agreement with theory.

The pulsed magnetic quadrupole lenses have been developed for focusing high energetic ion beams in accelerators. To operate stably, the quadrupole lenses were built in optimized steel- free structures. Up to now a flux density above 14 T has been reached in a quadrupole of 22 mm aperture. This value is high than the values reached in superconducting quadrupole lenses.

The fiber-optic sensors are widely applied for measurements of various movement parameters of mechanical objects: angular shifts, vibrations, acceleration, angular, and linear velocities. The interferometers with single mode and multi mode optical fibers are often used in these devices. In this work the results of the research of the fiber Mach-Zehnder interferometer sensor characteristics are presented. The sensor was used to measure vibrations and accelerations.

This paper presents the experimental study of the period- doubling phenomenon occurring during the multi-cycle processing procedure incorporating the exposure of Ag halide photoemulsion with the primary recorded holographic structure to the short-wave UV radiation, washing and drying. It is suggested that the simultaneous presence of two contrary photochemical processes -- photodecomposition and radiation hardening in the gelatin results in instability of the primary holographic structure and in the formation of the spatial subharmonic of the surface relief. The phenomenon may be considered as a process of the self-organization initiated by instability of the macrostructure on a rearrangement of the microstructure on the molecule level. The period-doubling phenomenon has been found to occur in the experiments with the UV sources of a various spectral composition -- the mercury- vapor lamp and the excimer lamps operating on the mixtures of Xe+Cl₂ and Kr+Cl₂.

One-dimensional quantum hydrodynamic equations jointly with divergent equation for the electric field are applied to describe motion of electron fluid with self-consistent electric field. This means automatically that the self-field of single electron is taken into account. The quantum hydrodynamics equations are presented and discussed for the single electron and many-electron system. One-dimensional models of motion were used in numerical study of the dynamic properties such as the spatial distribution of the probability density, the electric field, and the quantum potential. The Fourier spectra of solutions were analyzed also. Self- consistent solutions for the motion electron fluid through the background positive charge were compared with that in an 'empty' space.

The processes of the muonium and antimuonium creation in hadron-nucleon interactions on hadron colliders are considered. The total cross-sections are calculated. The method of muonium and antimuonium registration is considered. The possibility of CPT-invariance examination due to decay curve oscillation of muonium and antimuonium decay curve is discussed.

In this contribution we present the results of many-body calculation on electron photodetachment from inner subshells of Sn^- negative ion. The main attention is paid to qualitative changes in the near threshold 4d cross section induced by rearrangement effects.

In this work we have developed a simple self-consistent spherical model for the treatment of the outer shell electron structure in the fullerene C₆₀ molecule, starting from the self-consistent solution of the Kohn-Sham equation within the local-density approximation (LDA) for the exchange-correlation functional E_xc[(rho) ]. Our model is applicable for the many-body description of various collision processes involving the fullerene C₆₀, in which only valence electrons are important. Using our model one can describe the plasmon resonance structure in the photoabsorption and electron loss spectra in the vicinity of 19 eV.

In this work we report on the results of many-body quantum treatment for the inelastic scattering of fast electrons on metal clusters in the range of energies transferred above the ionization threshold. In this energy range, many-electron collective excitations provide significant contribution to the cross section. Above the cluster ionization threshold, the volume plasmon is the most significant many-electron excitation because its resonance frequency is located above the ionization threshold. We performed calculation of the electron inelastic cross sections using two different approaches. First, we calculated the cross section in the RPAE with the Hartree-Fock jellium model wave functions, accounting for both all single particle and collective excitations in the cluster. In order to extract contribution of plasmon excitations, we have also obtained the cross section in the plasmon resonance approximation.

In this work we present the results of the theoretical calculations of a ballistic conductivity of smooth and modulated quantum wires under nonideal conditions, i.e. at nonzero temperature and finite longitudinal bias. Deviations from the Landauer-Buttiker theory are described.

Optically induced metastable centers are studied in As₂S₃ chalcogenide glasses using the magnetic susceptibility technique for 3.5 K <EQ T <EQ 300 K. The temperature dependencies of the magnetic susceptibility ((chi) ) exhibit spin instability of both a hole center localized at a nonbonding lone pair chalcogen orbital and an electron center formed by an As p orbital. The (chi) fatigue at low temperatures is shown to result from the negative-U dissociation of paramagnetic states 2D^O yields D^- + D⁺ that causes also the absence of an ESR signal before illumination. Irradiation with light whose energy corresponds to the Urbach tail of the absorption edge is found to result in a growing (chi) signal that is due to optically induced paramagnetic states revealed also by the EPR signals: D^- + D⁺ + hv yields 2D^O, whereas subsequent irradiation with infrared light in the mid-gap bleaches both the optically induced magnetic susceptibility and ESR signal to its cold dark efficiency. Metastable properties for paramagnetic states located in the gap of As₂S₃ are discussed in the framework of the negative-U reaction that is accompanied by the restoration of the PL and the fatigue of the ESR signals and the magnetic susceptibility value.

We present the findings of the room temperature operation that is demonstrated by the single-hole silicon memory cell in which the single-hole silicon transistor is used as an electrometer. This memory cell is performed on the basis of the quantum wire and the quantum dot which is self-assembly formed as a multiple-tunnel junction by short-time diffusion of boron into the Si(100)-wafer. The single-hole device obtained exhibits the Coulomb oscillations and the memory effects as a hysteresis in CV characteristics which are respectively revealed by varying the gate and drain-source voltage in the process of the local tunneling spectroscopy measurements.

The pattern of light induced degradation, i.e. the degree of degradation of a-Si:H pinpin solar cells parameters, was studied on different i-layer thickness using high intensity (approximately 10 AM 1.5) illumination. It was found that stacked cells do not show a uniform degradation pattern as in the case of single junction solar cells. In particular, the degradation in shortcircuit current I_sc of the stacked cells shows a big difference for thick (approximately 500 nm) and thin (approximately 400 nm) pinpin cells. It was found that the degradation of the stacked cells with thick bottom layers exhibit a degradation pattern similar to that of single junction cells, i.e. the degradation in efficiency comes from the fill factor and the short circuit current, while open circuit voltage being degraded slightly. The degradation in short circuit current of cells with thin bottom layers is negligibly small.

The effect of trapping centers on the conductivity of amorphous 2,4,7-trinitro-nine-fluorenone (a-TNF) was investigated by space charge limited current (SCLC), thermally stimulated current (TSC), and transient photoconductivity methods. It is found that electron traps in a-TNF have a smoothly varying distribution centered at about E_t equals 0.29 +/- 0.04 eV with a dispersion parameter (sigma) equals 0.11 +/- 0.02 eV. The true activation energy at room temperature is E_a equals 0.45 +/- 0.03 eV. The zero-field extrapolated activation energy is E_ao equals 0.65 +/- 0.02 eV. It was suggested that the transport of charge carriers in a-TNF was controlled by traps. The concentration of traps and drift mobility of electrons was evaluated.

In this paper we present a simple non-destructive method for testing SiC plate single-crystals of any size and shape. The method is based on measuring the impedance changes of an inductive ferrite-cored coil due to placing the sample into the core gap. The method is valid for any SiC polytypes, though we used 6H one. Using this method we have obtained and discussed a conductivity as a function of doping level (N_d-N_a) for 6H-SiC Lely crystals. The conductivity measurements were carried out with alternating current of 747 kHz frequency. The sensitivity of the method is limited by minimal conductivity 1 (Ohm(DOT)cm)^-1 (that is corresponding to (N_d-N_a) approximately 2 (DOT) 10¹⁶ cm^-3 for 6H-SiC:N Lely crystals).

Scanning Kelvin microscopy (SKM) has been applied to the characterization of poled non-linear optical (NLO) polymer films, carbon black filled epoxy polymers and sulfur- passivated GaAs(100). This paper demonstrates that SKM is applicable to the detection of the magnitude and the direction of the field-induced polarization in poled NLO polymer films. We compare the response to that obtained from the scanning second-harmonic-microscopy method in which the direction of the orientation cannot be seen. A local illumination of the GaAs(100) surface during treatment in sodium sulfide solutions has significant influence on the work function distribution on the passivated surface. The image of the lateral distribution of the carbon black electrical network in epoxy resin by SKM is demonstrated.

Effects of infrared light irradiation (IR) on cultured dorsal root ganglia cells were studied by the whole-cell patch-clamp technique. The IR field is demonstrated to diminish the effective charge transfer in the activation system from 6.2 +-0.6 to 4.5 +-0.4 in units of electron charge per e-fold change in membrane potential. The effects was blocked with ouabain. Our data is the first indication that sodium pump might be the molecular sensor of infrared irradiation in animal kingdom.

In this contribution, we report on a study of the growth of fullerens from small clusters. A key factor in molecular dynamics modeling is the choice of interatomic potential. Ab initio molecular dynamics requires extensive computer resources, so that is outside the scope of most complex systems. We have developed simpler molecular dynamics model of charges at bonds which takes into account the electronic and atomic degrees of freedom and which can be implemented using a personal computer. Our approach has the possibility of studying the excited states formed by electronic transitions. The fundamental difference is that previously one only considered the static atomic subsystem whereas now we investigate both subsystems, atomic and electronic simultaneously. We have found that the cluster growth is accompanied by the resonance of the electronic and atomic degrees of freedom.

Cluster assembled materials represent a novel class of nanostructured solids which properties may strongly deviate from those of single crystal or amorphous solids with the same composition. At present time, most studies report about mono- elemental nanostructured materials. However, alloys and, in particular, bimetallic systems are well known for their technological interest and are of high innovative potentialities in their nanostructured form. The aim of the present work is to model on the atomic scale the structural and segregation properties in the Ni_xAl_1-x bimetallic nanostructured materials that are synthesized from isolated clusters. Therefore, we use classical Molecular Dynamics (MD) and Metropolis Monte-Carlo (MC) techniques. The combination of MC and MD codes allows modelling both the syntheses of these materials and the segregation phenomenon.

3D Monte Carlo model of epitaxial growth and sublimation process on {111} surfaces of diamond like crystals was developed. Using original rapid algorithm we could simulate crystal fragments with hundreds atomic layers in the depth. One monolayer could contain up to 10⁵ atoms. The model permits voids and overhanging formation. Arbitrary initial surface relief could be prescribed. The results of simulation are the computer film, demonstrating evolution of surface morphology, and data showing the degree of surface roughness. This model was successfully applied for simulation of homoepitaxy on (111) porous silicon surfaces.

A model is reported of ionic chain for describing mixtures of binary molten halides with univalent cations. The energy of chain and entropy is found. The energy consists of Coulomb and polarization units. The last term is calculated using the model of uniformly polarizable quasi-hard sphere. Calculated results are in a good agreement with experiment.

The first stage of the interaction of carbon with the silicon surface is the formation of the carbon induced Si(100)c(4X4) and the Si(111)((root)3x(root)3)R30 degree(s) reconstruction. This stage of the carbon silicon interaction was used to determine the surface diffusion coefficient of carbon on reconstructed (100) and (111) silicon surfaces with in situ reflection high energy electron diffraction. The parameters were determined by using a phenomenological model describing the time dependence of the surface phase transition.

This paper includes the results of experimental investigation and calculations of changes in residual stresses in NiTi shape memory alloys. For this purpose, the test of thermal and mechanical loading on the samples of Ni₅₀Ti₅₀ was performed. One-way and two-way shape memory effects were observed during loading and heating, i.e. SME alloy can be deformed, then recover its original shape when heated to a certain temperature. After this experiment the investigation using X-ray method was performed. In our experiments we used X-ray diffraction of the austenite phase of NiTi at room temperature to investigate the changes of elastic fields during thermal and mechanical loading. Diffractometer data were used for calculations of residual stresses. Root-mean- square (RMS) strains and sizes of coherent scattering regions were calculated using harmonic analysis. Based on the experimental data, the modeling results are depicted. Computer simulation takes into consideration martensite transformations, twinning, elastic and irreversible deformations. The result of thermal and mechanical loading and computer simulation provide data for shape memory alloys behavior under cyclic loading.

It is well known that TiNi shape memory alloys demonstrate the accumulation of significant unelastic strain near the temperatures of martensitic transformation. To study the physical mechanisms resulting in this effect simultaneous measurements of electrical resistivity, stress and strain were performed. It was founded that the mechanical stress practically does not facilitate to B2 yields R transformation, but can stimulate B2 yields B19'transitions.

Martensitic high Cr (10 - 16%) steels alloyed with Ni (Co), Mo, W, V, and N are widely used in constructions subjected to cyclic loads at temperatures up to 600 degrees Celsius, in general after quenching from 1100 - 1150 degrees Celsius followed by tempering at 650 - 690 degrees Celsius. Due to long term service exposure at high temperatures, different microstructural changes take place, such as second-phases precipitation, formation of low-angle grain boundaries, as well as internal damage caused by cyclic loads and creep. Specific phase diagrams are presented that can be used to define time periods for reliable operation of parts with given composition, based on the time required for the appearance of second phase particles known to be detrimental to mechanical strength and performance. Restoring thermal treatments to be applied after long time exposure at service conditions, aiming at increasing service life, are also presented and discussed. The combined use of the diagrams and the restoring treatment ensures prediction of a reliable service-life period for components made of these steels.

In this contribution, we report on a study of the self- organization of polypeptides. The process is computer simulated by the method of molecular dynamics. We investigated a set of polymers composed by different amino acids. The amount of monomers was 100 - 200 (700 - 2000 atoms). We observed spontaneous transitions of the polymer chains from initial linear configuration to loose and compact globules as well as following untwisting of globules. In some cases the self-organization was similar to that obtained earlier for a beads-on-a-string model and simple organic polymers. The specific role of different amino acids in the protein self- organization was investigated.

Molecular dynamics investigation of diacyldlycerolipid (DG) monolayers was carried out. Each lipid molecule contained stearic fatty acid chain (C_18:0) in position 3-D and one of the fatty acid chains C_18:0, C_18:1(omega 9), C_18:2(omega 6), C_18:3(omega 3), C_20:4(omega 6) or C_22:6(omega 3) in position 2-D [for the nomenclature see M. Sundaralingam, Ann. N.Y. Acad. Sci. U.S.A., 195, 324 - 355 (1972)]. A polar head group of the lipid molecules was treated as an effective sphere. 1.5 nanosecond simulations were performed at temperature 303 K for monolayers 18:0/18:1(omega) 9cis DG, 18:0/18:2(omega) 6cis DG, 18:0/18:3(omega) 3cis DG, 18:0/20:4(omega) 6cis DG, 18:0/22:6(omega) 3cis DG and at T equals 326 K for 18:0/18:0 DG monolayer. The monolayers consisted of 48 glycerolipids of the same type arranged in a rectangular simulation cell. The average areas per lipid molecule over the simulations were 65.6 Angstrom² in 18:0/18:0 DG monolayer, 66.2 Angstrom² in 18:0/18:1(omega) 9cis DG, 66.1 angstrom² in 18:0/18:2(omega) 6cis DG, 67.4 angstrom² in 18:0/18:3(omega) 3cis DG, 70.6 angstrom² in 18:0/20:4(omega) 6cis DG and 71.4 Angstrom² in 18:0/22:6(omega) 3cis DG monolayer. The C-C bond orientation distributions and C-C bond order parameter profiles about the monolayer normals were calculated. The C-C bond orientation distribution function widths turned out to be depended on both bond location in the chain and chemical structure of the segment.

Molecular dynamics simulations were carried out for bilayers of lipid molecules having stearic acid (C_18:0) chain in position '3-D' (using the nomenclature of M. Sundaralingam, 1972) and fatty acid chain C_18:0, C_18:1(omega 9), C_18:2(omega 6), C_18:3(omega 3), C_20:4(omega 6) or C_22:6(omega 3) in position '2-D'. To investigate the properties of the bilayers two models were considered. In the first model, the simulation cells of the bilayers consisted of 96 phosphatidylcholine (PC) molecules and 2304 water molecules: 48 lipid molecules per layer and 24 H₂O molecules per lipid. The water was modeled by explicit TIP3P water molecules. In the second model, the head group of the lipid molecules was treated as an effective sphere -- diacylglycerolipids (DGs) were considered, the interface of each monolayer was modeled by a flat surface; no water molecules were present explicitly. The bilayers consisted of 48 X 2 equals 96 glycerolipids arranged in a rectangular simulation cell. Various properties of the bilayers -- the C-H bond order parameter -S_CH profiles of the hydrocarbon tails, the root-mean-square values of the positional fluctuations of the lipid chain carbons, mass density distributions of lipid molecules and water along the normals were investigated.

Monte Carlo computer simulations of chain molecules with a predetermined chemical structure were carried out. Variations of all torsion angles of the chains were considered to be continuous from 0 to 360 deg in contrast to the rotational isomeric scheme. The method is applied to an investigation of shape and dimension characteristics (and their temperature coefficients at temperatures 278 - 298 K) of unperturbed linear hydrocarbon chains CH₃-(CH₂)_x-(CH equals CH minus CH₂)_y-(CH₂)_z-CH₃ of 14 - 22 carbons with 1 - 6 methylene-interrupted cis-double bonds. The molecule-fixed coordinate system with the axes along principal axes of inertia of each molecule conformation was used. A close relationship between these characteristics and the structure of the molecules was elucidated.

As known the long-term electrical activity of a neuron is accompanied by changing expression of early and late genes (Greenberg et al. 1985). Results of these changes are synthesis of ion channel proteins (Garcia, et al. 1994) and neurotransmitters (Hodaie et al. 1995) translating short-term environmental signals into relatively long-term changes in neuronal function. Transcription of early genes is activated within minutes of stimulation (Morgan and Curran 1986). Late gene expression is induced more slowly, within hours, and is controlled by regulators proteins that are products of the early genes (Goldman et al. 1988). Action of neurotransmitters, neurotrophic growth factors, and the membrane depolarization are thought to be stimuli inducing expression of early genes (Morgan and Curran 1991). One of the early genes widely used in experimental studies is c-fos gene that participates in responses to brain injury, sensory stimulation, activation of neurotransmitter receptor, stress, and long-term changes in efficiency of synaptic transmission (Hughes and Dragunow 1995). Transmission of information about changes of electrical stimulus from the neuronal membrane to genes is realized by several different intracellular signaling pathways in activation of which the second messenger Ca plays an essential role. Such structure of the signal transmission allows us to separate the problem of defining stimulustranscription coupling into two ones: . determination of relations between parameters of temporal pattern of electrical stimulus and parameters of temporal pattern of oscillations of intracellular calcium concentration ([Ca]), . identification of relations between parameters ofthe temporal pattern of [Ca] oscillations and expression intensity.

We analyze the hypothesis for existence of two independent factors, realizing of contractile properties of blood vessels in response to transmural pressure changes. The factors are a degree of vascular wall stretch and its circumferential tension. We suggest the method for qualitative and quantitative evaluation of the sensitivity of the active component of the vascular wall tension to these factors. The method favors a sophisticated understanding of mechanic regulation of vessels and hemodynamics.

The recent multifaceted studies on the electronic stopping powers and ranges of the relativistic heavy ions (with Z₁ > 50) in the matter indicate on the significant deviation of the experimental observations from the related predictions based on the first order quantum perturbation theory. Incorporation of the high-order corrections of perturbation theory into theoretical description leads to reasonable prediction both of the mean energy losses and of the mean total ranges of relativistic heavy ions. At the same time, the effect of high order corrections on the fluctuations of the heavy ion ranges is still not so clear. This work presents the recent experimental observations of the ranges and the range stragglings of relativistic heavy ions in the BR2 photoemulsion. We also performed related theoretical calculations that include the high orders corrections of perturbation theory both for the electronic stopping powers and for the energy loss straggling. The role of high order effect in an estimation of the range fluctuations is discussed.

The behavior of (alpha) -Fe alloys with molybdenum and tungsten carbides and oversize substitutional atoms under reactor irradiation has been investigated to study the possibility to substitute the molybdenum atoms for tungsten ones in order to create low activated steels. Computer simulation of collision cascades was used to study the damage of iron targets with Mo and W impurities and carbides under irradiation. It was found that at the ballistic stage of radiation damage the tungsten carbides are damaged to a higher degree and can be destructed more effectively than molybdenum carbides because of differences in interatomic potentials.

The diffusion processes in silicon carbide under Al⁺ and N⁺ ion implantation and subsequent annealing have been investigated. The influence of an internal stress field due to point defect clusters has been taken into account. The clusters of interstitials, ions, and impurities have been created during irradiation. The compression stress field due to these complexes has decreased the diffusion of interstitials. The defect profiles have been calculated which have been in good agreement with experimental RBS/C results.

The response of ferroelectric materials to high energy irradiation is of great interest because of their possible application in radiation environments such as thermonuclear reactors. In the present work a physical model for the defect evolution in PLZT ceramics under neutron irradiation and annealing is proposed. The influence of the defect system on the ferroelectric properties of these materials has been investigated. Satisfactory agreement between the theoretical estimated oxygen defect concentration after irradiation and annealing and the experimentally determined polarization has been obtained.

A theoretical model is suggested which describes the evolution of ensembles of point defects that give rise to solid state amorphization in initially crystalline films under irradiation. A kinetic equation for the density of point defects (vacancies and interstitial atoms) in irradiated solid films is proposed and solved with the assumption that the effect of ion implantation on the amorphization is negligible. In the framework of the proposed model, the temperature dependence of the dose-to-amorphization is calculated and compared with the corresponding experimental data [H. Abe et al, Nucl.Instrum. Meth. Phys.Res. B 127/128, 170 - 175 (1997)].

The combined experimental and computer simulation technique for the estimation of the displacement threshold energies of impurity atoms in materials has been developed. The technique is based on SIMS sputtering profiling of structures with thin impurity marker layers and computer simulation of this process. Using this technique the displacement threshold energies of Al atoms in GaAs matrix and Sb atoms in Si matrix have been estimated.

The CO₂ laser induced optimization of the thermal coefficient of electrical resistivity in Co-Ti-Si thin films is realized. The X-ray diffraction studies of the annealed Co- Ti-Si films confirm that the changes of electrical properties are related to forming a small structure of crystalline compounds Ti₅Si₃ and CoSi₂ in an amorphous matrix.

The problem of motion of a half-space filled by Kandaurov granular medium after applying to its surface a normal load is considered. Kandaurov medium consists of small rigid particles that are in contact with adjacent ones. The particles have random shapes, and their characteristic diameters converge to zero, so the stresses and strains of the medium are random. The model takes in account internal friction between the particles using Voigt law.

A theoretical model is proposed for the cohesive failure of multilayer composite systems. A general formula is derived which relates values of structural and geometrical parameters at which crack generation is energetically favorable in such composite systems. For one-layer film/substrate systems, the critical thickness is found above which the cohesive fracture of films is energetically favorable. Nucleation of an intermediate layer due to diffusion across a film/substrate interphase boundary is considered. It is shown that the generation and the growth of the diffusion layer may result in the spontaneous cracking of the film.

This paper presents a theoretical model to determine the superficial inside and outside residual stresses in girth weld pipes. The model is an analytical solution using geometric dimensions of the pipe, material properties and the weld procedure in order to define the residual stress distribution which was compared with the experimental measurements by x-ray diffraction method and with the results presented in other papers. The equations considering the most important variables of the problem were proposed to obtain a quick residual stress estimation in the middle of the weld metal of the joint. The proposed model is useful to preview the welding process stresses as well as allowing welding variables study sensibility and the residual stress optimization. The model considers all inherent simplification applied to the theory.

The residual stress profiles in speed gears for automotive vehicles were determined. The profiles were measured at the root between two teeth of the gears by x-ray tensometry without the necessity of cutting the pieces. The gears were cemented, quenched and annealed. After this heat treatment, compressive residual stresses were introduced by shot-peening. The profiles indicate the maximum residual stress of -950 MPa (compressive) at a depth of 0.05 mm. The stresses are zero at a depth of 0.25 mm. In the gears without shot-peening the maximum residual stress at the surface is -600 MPa (compressive) and is zero at a depth of 0.30 mm.

The influence of crack path configuration on its growth rate is considered. The straight and zigzag-like crack models are compared for the different stages of propagation and various loading conditions. Comparison of numerical results based on elasto-plastic finite element analysis and experimental data has been presented and discussed. The possible modification of classical fatigue lifetime prediction equations are discussed with aim to take into consideration the kinking effect at the initial stage of crack propagation.

We report on simultaneous monitoring of electrical resistance and acoustic emission (AE) during cyclic tensile loading of cross-ply carbon fiber reinforced plastics (CFRP). The parallel detection of the AE serves as a reference method for the investigation of the microscopic damage mechanisms causing the electrical response. During loading and unloading the samples, the electrical measurements show a hysteresis in the resistance versus strain plot. Exceeding the previous load maximum in the consecutive load cycle, a characteristic increase in the measured resistance-strain slope appears combined with a sudden rise in the AE (Kaiser effect). Thus, the reported in situ observation of the electrical resistance allows to distinguish virgin and damaged CFRP samples as well as to predict a previous load maximum by the characteristic change in the resistance-strain slope.

An SMA material model for use with finite element analysis is presented. Experimental results conducted to demonstrate and verify the concept closely matched the results obtained from FEA. Both one-dimensional and three-dimensional variations of the material models were used in the FE analysis. The one- dimensional SMA model was used to model the active twisting of a beam while the three-dimensional model was used to investigate stresses developed in a SMA reinforced smart composite plate. Surface-to-surface contact algorithms, nonlinear kinematics and nonlinear material model of SMA were used in FE analysis. A two-step approach was developed in order to analyze behavior of smart composite plates reinforced by SMA wires. Results from the analysis of changing the shape of wing prototype are also presented.

The paper presents 3D finite element (FE) approach to modeling pressure microsensor. It consists of two basic parts. In the first part the 3D finite element modeling itself is presented. The second part of the work deals with the FE structural and modal analysis of different 3D FE models. These researches will allow improve characteristics of the given sensor with the purpose of its further practical application.

The tiny engines, founded on the principle of reactive thrust, are one of most perspective actuators developed by modern micromechanics. These engines can be applied for such apparent problems, as orientation and stabilization of small space objects, but also as local or distributed reactive thrust of new phylum of aerospace objects, for control of boundary layer of flying objects and in series of converting power devices of different purposes. Distinctive features of jet tiny engines are profitability (very large thrust-to-weight ratio) and high (milliseconds) response, which makes them to irreplaceable elements in control systems and, specially, in distributed power generations. These features are provided the minimum sizes, high pressure in working chambers and hypersonic velocity of propulsive jet. Topologically micronozzles are designed as the flat batch devices (3 layers as minimum). The lower and upper layers make flat walls of the nozzle and mainly influence on strength properties of the device. The mean layer reshapes geometry and determines gas dynamic characteristic of the nozzle. A special problem is the opening-up of the combustion-mixture, which is not esteemed in this work. It is necessary to allow for effect of considerable local stresses arising at the expense of static and dynamic loading at design of the jet tiny engines. Thermal gas dynamic processes in the chamber and nozzle determine the values and nature of these stresses, which are hardly studied for the microdevices. The priority is mathematical and experimental simulation of these processes. The most suitable object for initial phase of experimental simulation is the 'cold' engine. The demanded chamber static pressure is formed by external compressed air. In Laboratory of Microtechnology and MicroElectroMechanical Systems a number of such tiny engines with different shapes of the chamber's and the nozzles' surfaces were designed, made and tested. The engines were produced from photosensing glass by methods of microtechnology on the basis of photolithography processes. After expositing through a mask the latent map of the glass was 'showed' by heat treatment and etched. The obtained parts sitallized and subjected to level-by-level assembly. At experiments on 'ardent' engines it is supposed to keep the basic stages of a technological route, but to use stronger and temperature- resistant materials including coating from high-strength membranes plotted by vacuum deposition methods. During trial tests, for the 'cold' engine with an altitude of a nozzle of 1.2 mm and width of the throat of 0.4 mm at chamber pressure 0.6 MPa the exhaust velocity on escaping of the nozzle about 1.5 M was obtained. The engine thrust has compounded 45 gr. The obtained data are in satisfactory conformity with 1D computation and allow to proceed piloting objects of other range of the characteristics. The microactuators having high response and profitability are demanded for perspective small aerospace objects. This activators are indispensable for creation of distributed thrust and control of boundary layer of micro air flying objects (MAV), for devices of stabilization and orientation of micro-satellites. A number of such activators forms on the areas of flat micronozzle devices. Developed micronozzles should provide demanded parameters at the expense of a high level of pressure in working chamber and supersonic exhaust velocities. At creation of the micronozzle the effect of considerable loads arising as at the expense of static, and dynamic loading should be mentioned. Thermomechanics-gasodynamic processes in the chamber and nozzle determine the nature and kind of loading. Mathematical and experimental simulation of these hardly studied for the microscopic object processes is necessary.

Measurements of acoustic pressure oscillations on curvilinear surface streamlined by a flow, for example, on the wall of wind-tunnel or airfoil is necessary to supply for aeroacoustic appendices. Microphone should have the minimal sizes and feeler set flush-mounted. Such microphones are demanded for creation distributed audio-systems and noise reduction devices in the source. Developed the MEMS-microphone with corrugated diaphragm should have a sharp response, stability to effects of ram airflow and high level pressure. Preliminary simulation of design and technological parameters is necessary for creation of this microphone.

The sensors measuring parameters of mobile objects are the important components of modern inertial systems. They should have sufficient accuracy, tiny sizes, and low cost at high reliability in operation. From all types of sensitive elements micromechanical gyroscopes and accelerometers most full meet the requirements mentioned above. Development of micromechanical sensitive elements is connected with the technology used in solid-state microelectronics (photolithography, isotropic and anisotropic etching, etc.) and application of nonmetallic materials (monocrystal silicon, silicon carbide, quartz, piezoceramics, etc.). Small-sized inertial navigating systems on the basis of micromechanical sensors at the appropriate integration with Global Positioning System (GPS) receivers provide high enough accuracy in the decision of navigation, orientation, and management problems. In this paper some experimental results received at manufacturing of a micromechanical vibrogyroscope are discussed. More full research of the given vibrosensor including reception of new practical results is carried out with the help of 3D finite element analysis.

The paper presents some results of the 3D finite element (FE) modeling of a catheter pressure sensor that is used for biomedical purposes. Its applications specificity entails some features at its designing and manufacturing that it is necessary to take into account at the FE analysis of the sensor.

Problems of static and dynamic simulation of the biomechanical system consisting of the human tibia bone and external fixator apparatus as the simplest frame construction are considered. The finite element method implemented as the program code MechanicsFE3D_ESO on the basis of 20 nodal isoparametric elements is utilized. Both general stressed-deformed state of the construction under transversal loading and basic frequencies and forms of free oscillations of the system were defined by the numerical analysis. The results obtained can be used as the theoretical fundament to developing of static and vibration resonance methods for physiological state diagnostics of the regenerating osseous tissue in fracture zone.

The computer model of high-speed elasto-plastic deforming of thin shell, fixed on complex contour was created. The model allow to estimate wave localization of plastic strains near with the contour of fixing. The two-dimensional problem of mathematical physics in Lagrangian - Euler coordinates describing major plastic strains of shell fixed on composite contour was designed. The strain hardening of material, elastic unloading, temporal law of pressure is taken into account. The implicit finite-difference algorithm of numerical solution using on each temporal step the special joint solution method of two systems of the nonlinear algebraic equations was designed and the program was implemented. The calculations have been shown possibility of localization of plastic strains and fractures of workpiece during electrohydraulic sheet metal forming.

Experimental - theoretical research of the plastic deformation of thin-walled steel and nickel tubular specimens was done. The experimental results and forecasts of the kinematical hardening model and multisurface model with one active surface were compared. A modification of the plasticity theory was gone. The modification takes into account character of a loading path. The constitutive equation gives the possibility to make predictive calculations when either loading or strain path (in whole strains) is known. The research is performed for complex periodic loading paths, containing partial and complete unloading.

We consider mathematical formulas for description of geometrical surfaces. The list includes such surfaces as plane, second degree surfaces (16 types), second degree super surfaces (16 types), multiple surfaces (above second degree). All these surfaces are described only by a single equation. This equation has coefficients that define type, size, and location of a surface in 3D space. We can design and locate a surface by changing of the sign and value coefficients. In the library of a computer these surfaces are written in a parametrical form as a value of surface coefficients. It is a very compact library. We have software for creation of complex geometrical objects, if needed to convert object form, location of these objects in space scene, moving and rotation these objects in scene, visualization 3D stereo scene. We do not have a planar computer model, we create a computer analytical model as records of surface coefficients in the computer memory and proceed these coefficients for our tasks. The analytical model is very compact. Visualization has a complex procedure and requests some time but can be solved by an asynchronous super computer.

The paper is devoted to snowmobile and car dynamics simulation in real time mode. This task is typical for trainers and computer games, where a model of moving vehicle is handled interactively. The challenge of real time is to recalculate values of a moving model on each frame, that is, at least 30 times per second and take for this not more than 5% processor time on an ordinary personal computer. We describe the minimal mathematical model and numerical method sufficient to simulate a snowmobile quite realistically. The approach proposed may be applied for various vehicle models.

Virtual reality systems gained a wide expansion nowadays. They appear as three-dimensional trainers and simulators, video games, various visualization systems, virtual www-spaces and so on. The area of applications for such systems is rapidly expanding that is supported first of all by a quick development of appropriate hardware and software tools. The main problem in the virtual reality systems is allowing a user to be effectively present in the space, navigate through it, and also to interact with the space, objects and characters (intelligent agents) embedded in the created synthetic space. One of the tasks raising on building the virtual reality system is creation of behavioral animation (or simply behavior) of intellectual agents. The behavior represents actions that are usually described with terms of natural speech, having social, psychological or physiological meanings that are not necessarily trivial in reducing to actual animation, i.e. to movement of effectors, skeleton etc.

The paper deals with new approaches in software design for creating real-time applications that use modern graphics acceleration hardware. The growing complexity of such type of software compels programmers to use different types of CASE systems in design and development process. The subject under discussion is integration of such systems in a development process, their effective use, and the combination of these new methods with the necessity to produce optimal codes. A method of simulation integration and modeling tools in real-time software development cycle is described.

In this paper we describe a mathematical model of gas dynamic process in the combustion chamber of a jet engine, programming of this model and visualization of the process. We use the geometric super surfaces 3-D model of the combustion chamber as the boundary conditions for this gas dynamic process. The Program (Visual C++ 6.0) calculates the system of non- linear unsteady equations which describe dynamics of the tough compressible transcalent gas under conditions diffusion and chemical reactions in 3-D space. Visualization of this process gives us color tone 2-D pictures (density, temperature, pressure, direction, and velocity) of gas flow in a chosen section on 3-D stereo translucent image of the jet engine combustion chamber in a current period time. We can use an asynchronous parallel super computer for acceleration of the calculation and visualization of this gas process.

Process parameters optimization in device/integrated circuits (IC) technology is an important and essential stage in the modern industrial cycle of the microelectronics industry. The use of the progressive computer and information technique enables to resolve this problem. Algorithms and results are presented for optimization of process parameters from the viewpoint of providing with acceptable deviations of IC devices performances. As input data for optimization we used results of real experiments obtained in industrial conditions. SPICE parameters of n-MOS transistor were analyzed.

Modified Response Surface Methodology (MRSM) is proposed for the approximation of numerical simulation results. This approach is based on the parametric statistics methods. The tensor products or Chebyshev's polynomials are used for the non-linear regression series in order to decrease the mean- square error. The MRSM algorithm is realized via Mathematica^R package. Results of investigations are proved on the basis of numerical simulation of the integrated circuit technology and analysis of the experimental data for thin film technology.

In this paper a technique of fitting of experimental data of thermally stimulated depolarization (TSD) (one of the widespread methods of dielectrics and high resistance semiconductors investigation, including parts of electrotechnical devices) is proposed. Theoretical substantiation and practical application of new methods of computer simulation for analysis of TSD currents are considered. Specific examples of experimental data fitting are given. Edges of the technique are shown. Some methods of computer simulation are recommended to experimenters for wide use.