Papers by Author: Alexander N. Timofeev

Abstract: The Volume Diffusion of Homovalent Atomic Probes (APs) from the VB Group of the Periodic Ta-Ble of Elements (PTE) – V and Nb in W Single Crystals Has Been Studied by Using the Method of Secondary Ion Mass Spectrometry (SIMS). the Parameters of the Arrhenius Dependence of the Coefficients DV of Vanadium Volume Diffusion in W Have Been Measured: (D0)V = (1.3  0.4) X 10-4 M2s-1 and QV = (564 ± 6) Kj/mol. the Parameters (D0,Q)Nb of the Bulk Diffusion of Nb Aps in W Have Been Estimated with the Help of Several Measured Coefficients Dnb and the Empirical Correlation [1,2]: (D = DWW)(Tm)W: the Diffusion Coefficients of Substitutional Non-Magnetic 5d-Aps Coincide with the Self-Diffusion Coefficients in W at its Melting Point (Tm)W. the Enthalpies Qnb,Ta of the Bulk Diffusion of Non-Magnetic (nm) Homovalent Aps from the VB Group of PTE – Nb and Ta [3] Also Coincide with the Relaxation Volumes vacVBAPs of Complexes “vacancies-VB Aps” in the W Lattice. Electron Contributions (EDN)vacVBAPs to the Energies Evacvbaps of Interaction of Point Defects in Complexes “vacancies- VB Nm- Aps” Are Lower than in Complexes “vacancies-IVB Nm- Aps” [4]. the Dependence of {EDN(n)}vacVBAPs the Electron Contributions (EDN)vacVBAPs on the Difference of N Numbers of Periods of PTE the Deviation of Contributions (EDN)vacVAPs for Vanadium Aps to En-Ergies Evacvaps of their Interaction in Complexes “vacancy-VAP” Has Been Determined. this Devi-Ation Is Conditioned by the Contribution of the Exchange Energy (Eexch)VAP of Vanadium to the En-Ergy Evacvaps of the Point-Defect Interactions in the Complex “vacancy-VAP”.

Abstract: The Volume Diffusion of Homovalent Atomic Probes (APs) from the VIB Group of the Periodic Table of Elements (PTE): Сr, Mo, W and from the VIIB Group of the PTE: Mn, Tc, Re in W Single Crystals Has Been Studied by Using Secondary Ion Mass Spectrometry (SIMS) and Radiometric Layer-by-Layer Analysis. the Enthalpies Q of the Bulk Diffusion of Homovalent APS from the VIB Group (Сr, Mo, W) and from the VIIB Group (Mn, Tc, Re) of PTA Increase with the Growth of N Numbers of their Periods in each Group whereas the Relaxation Volumes  of the Complexes “va-Cancies- VIB, VIIB Aps” in the W Lattice Do Not Differ Practically. the Detected Change of En-Thalpies Q Is Conditioned by the Difference in Magnetic Moments of Homovalent Aps from the VIB and VIIB Groups of PTA in Complexes with Vacancies in the W Lattice.

Abstract: The bulk diffusion of homovalent non-magnetic atomic probes (APs) from the IVB group of the periodic table of elements (PTE) – Ti and Zr in tungsten single crystals was investigated by sec-tioning, using secondary ion mass spectrometry (SIMS). The Arrhenius dependences had the fol-lowing parameters: DWTi - (D0)WTi = (3.00.4 ) x 10-4 m2s-1, enthalpy QWTi = (576 ± 9) kJ/mole; DWZr - (D0)WZr = (2.3  0.6) x 10-4 m2s-1, QWZr = (561 9) kJ/mole. The measured parameters (D0,Q)WTi,Zr of diffusion of Ti and Zr atomic probes (APs) in W are in accord with the empirical correlation: the diffusion coefficients of the substitutional APs coincide with the self-diffusion coefficients in W at (Tm)W – its melting temperature. Enthalpies QWTi,Zr,Hf of the volume diffusion of homovalent non-magnetic APs of the IVB group of periodic table of elements (PTE) - Ti, Zr and Hf increase with the decrease of relaxation volumes of the complexes «vacancy-IVBAP» in W lattice. The energies (E)WvacIVBAP of elastic relaxation of the complexes «vacancy-IVBAP» in W lattice were estimated. Electron contributions EDN to the energies EWvacIVBAP of interaction of the point defects in complexes «vacancy-IVBAP» increase relative to value EWvacIIIBAP of interac-tion of the point defects in complexes «vacancy-IIIBAP» with the growth of d-electrons number in comparison with the complexes «vacancy-IIIBAP».

Abstract: The volume diffusion of nonmagnetic homovalent atomic probes (APs) from the IIIB group of the periodic table of the elements (PTE)Sc, La, and Th in Whas been studied by the method of secondary ion mass spectrometry. The Arrhenius dependences have the following parameters: the coefficients DSc - (D0)Sc = (1.4  0.3)10-4 m2s-1 and QSc = (546±4) kJ/mole; the coefficients D¬La - (D0)La = (1.6  0.8)×10-6 m2s-1 and QLa = (41010) kJ/mole; and the coefficients DTh - (D0)Th = 4.4×10-6 m2s-1 and QTh = 447 kJ/mole. It has been found that the coefficients D5dAP(Tm)W of the bulk diffusion of transition 5d APs in W coincide at its melting point (Tm)W. The enthalpies, QWSc,La,Th, of the volume diffusion of nonmagnetic homovalent APs from the IIIB group of PTE increase linearly with decreasing relaxation volumes, , of these APs, which interact with vacancies in W. The sums, (Q + E)WSc,La,Th, of the bulk diffusion enthalpies, QWSc,La,Th, and the relaxation energy, (E)WSc,La,Th, of the environments of homovalent APs diffusing to W are nearly constant.

Abstract: The control of railway track position is an important application area for coordinate measuring optoelectronic systems. One of the methods for the railway track control consists in determination of railway track position relatively to reference marks, which are mounted along the track [1]. In general case this system should be mounted on liner-tamper-surfacer and provide measurements of reference marks coordinates. Marks can be positioned up to 10 meters from track and measurements must be carried out in automatic mode. It has been decided to project the system on basis of inner-base rangefinder’s scheme [2].

Abstract: The construction of new radio telescope RT-70 Suffa requires controlling the angular and linear deformation of the mirror elements. Following issues dealing with this problem are described in this article: 1) the possibility of the design of deformation measurement system based on triangular method 2) the new scheme of optic-electronic measurement system. The great attention during the research was paid to the experimental approval of the theoretical results. The computer simulation error and the experimental error measurement was 0.08 mm at the range 30 mm on a working distance of 25 m, which allows measuring the deformation of radiotelescope construction with the mirror diameter 70 m.

Abstract: Large or long objects require measuring systems as a combination of more than one measuring instrument. In this case, the combination of instruments consists of one central module and several measuring modules. The measuring modules make the preliminary computation of measuring information and translate it to the central module for final computation of measuring parameters. The central module also makes statistics of measuring and archive information. Some tasks require noncontact measurement of angular and linear coordinates of objects or places. The optoelectronic measuring devices (OEMD) are ideal for these purposes. These devices also have other advantages such as high precision and adaptability. One and two coordinates high precision modules based on matrix and linear CCD or CMOS photo sensors are described. In this article variants of the distributed measuring systems are described. The basic attention is given to the description of the unified optoelectronic modules for measurement of angular and linear coordinates. Basic parameters and application examples of measuring modules are presented.