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Search Results: 1 - 10 of 167948 matches for " Aleksey E. Bolotnikov "
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Properties of Pt Schottky Type Contacts On High-Resistivity CdZnTe Detectors
Aleksey E. Bolotnikov,Steven E. Boggs,C. M. Hubert Chen,Walter R. Cook,Fiona A. Harrison,Stephen M. Schindler
Physics , 2001, DOI: 10.1016/S0168-9002(01)01506-6
Abstract: In this paper we present studies of the I-V characteristics of CdZnTe detectors with Pt contacts fabricated from high-resistivity single crystals grown by the high-pressure Brigman process. We have analyzed the experimental I-V curves using a model that approximates the CZT detector as a system consisting of a reversed Schottky contact in series with the bulk resistance. Least square fits to the experimental data yield 0.78-0.79 eV for the Pt-CZT Schottky barrier height, and <20 V for the voltage required to deplete a 2 mm thick CZT detector. We demonstrate that at high bias the thermionic current over the Schottky barrier, the height of which is reduced due to an interfacial layer between the contact and CZT material, controls the leakage current of the detectors. In many cases the dark current is not determined by the resistivity of the bulk material, but rather the properties of the contacts; namely by the interfacial layer between the contact and CZT material.
Effects of Bulk and Surface Conductivity on the Performance of CdZnTe Pixel Detectors
Aleksey E. Bolotnikov,C. M. Hubert Chen,Walter R. Cook,Fiona A. Harrison,Irfan Kuvvetli,Stephen M. Schindler
Physics , 2001, DOI: 10.1109/TNS.2002.801673
Abstract: We studied the effects of bulk and surface conductivity on the performance of high-resistivity CdZnTe (CZT) pixel detectors with Pt contacts. We emphasize the difference in mechanisms of the bulk and surface conductivity as indicated by their different temperature behaviors. In addition, the existence of a thin (10-100 A) oxide layer on the surface of CZT, formed during the fabrication process, affects both bulk and surface leakage currents. We demonstrate that the measured I-V dependencies of bulk current can be explained by considering the CZT detector as a metal-semiconductor-metal system with two back-to-back Schottky-barrier contacts. The high surface leakage current is apparently due to the presence of a low-resistivity surface layer that has characteristics which differ considerably from those of the bulk material. This surface layer has a profound effect on the charge collection efficiency in detectors with multi-contact geometry; some fraction of the electric field lines originated on the cathode intersects the surface areas between the pixel contacts where the charge produced by an ionizing particle gets trapped. To overcome this effect we place a grid of thin electrodes between the pixel contacts; when the grid is negatively biased, the strong electric field in the gaps between the pixels forces the electrons landing on the surface to move toward the contacts, preventing the charge loss. We have investigated these effects by using CZT pixel detectors indium bump bonded to a custom-built VLSI readout chip.
Semi-Markovian Model of Monotonous System Maintenance with Regard to Operating Time to Failure of Each Element  [PDF]
Yuriy E. Obzherin, Aleksey I. Peschansky
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.28055
Abstract: An explicit form of reliability and economical stationary performance indexes for monotonous multicomponent system with regard to its elements’ maintenance has been found. The maintenance strategy investigated supposes preventive maintenance execution for elements that has attained certain operating time to failure. Herewith for the time period of elements’ maintenance or restoration operable elements are not deactivated. The problems of maintenance execution frequency optimization have been solved. For the model building the theory of semi-Markovian processes with a common phase field of states is used.
Semi-Markovian Model of Monotonous System Maintenance with Regard to its Elements’ Deactivation and Age  [PDF]
Yuriy E. Obzherin, Aleksey I. Peschansky
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.13029
Abstract: An explicit form of reliability and economical stationary performance indexes for monotonous multicomponent system with regard to its elements’ maintenance has been found. The maintenance strategy investigated supposes preventive maintenance execution for elements that has attained certain operating time to failure. Herewith for the time period of elements’ maintenance or restoration operable elements, functionally connected with the failed ones, are deactivated. The problems of maintenance execution frequency optimization have been solved. For the model building the theory of semi-Markovian processes with a common phase field of states is used.
Semi-Markovian Model of Control of Restorable System with Latent Failures  [PDF]
Yuriy E. Obzherin, Aleksey I. Peschansky, Yelena G. Boyko
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.23046
Abstract: Mathematical model of control of restorable system with latent failures has been built. Failures are assumed to be detected after control execution only. Stationary characteristics of system operation reliability and efficiency have been defined. The problem of control execution periodicity optimization has been solved. The model of control has been built by means of apparatus of semi-Markovian processes with a discrete-contin- uous field of states.
Infant Vocalizations at the First Year of Life Predict Speech Development at 2 - 7 Years: Longitudinal Study  [PDF]
Elena E. Lyakso, Olga V. Frolova, Aleksey S. Grigorev
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.512154
Abstract:

The authors present the results of a 7-year longitudinal study of 10 Russian children beginning at birth up to 7 years old. The relationships among vowels diverse, babbling, imitative activity during the first year of a child’s life, the amount of the first words at the age of 12 months, stressed vowels duration and pitch variation in mother speech addressed to children of the first year of life, the risk of development of birth, were investigated as predictors of speech development in 2 - 7 years. The results are shown that those characteristics predicted complexity of replica in dialogues, compound phrases using, ability to retell, and reading skills formation. The risk of development at birth manifested in EEG-rhythm age immaturity in 7 years that was reflected in speech skills and reading comprehension.

On some local properties of Yang-Mills vacuum
E. I. Guendelman,Aleksey Nudelman
Physics , 1997, DOI: 10.1142/S0217751X98000871
Abstract: In this paper we use a non-covariant gauge which makes some of the YM features manifest which otherwise do not appear explicitly in the Landau gauge used by Nielsen and Olesen.We show, in fact, that the unstable mode which makes a large contribution to the vacuum energy is non-perturbative even classically.
A uniqueness result on boundary interpolation
Vladimir Bolotnikov
Mathematics , 2006,
Abstract: Let $f$ be an analytic function mapping the unit disk $\D$ to itself. We give necessary and sufficient conditions on the local behavior of $f$ near a finite set of boundary points that requires $f$ to be a finite Blaschke product.
On a multi-point interpolation problem for generalized Schur functions
Vladimir Bolotnikov
Mathematics , 2008,
Abstract: The nondegenerate Nevanlinna-Pick-Carath\'eodory-Fejer interpolation problem with finitely many interpolation conditions always has infinitely many solutions in a generalized Schur class $\cS_\kappa$ for every $\kappa\ge \kappa_{\rm min}$ where the integer $\kappa_{\rm min}$ equals the number of negative eigenvalues of the Pick matrix associated to the problem and completely determined by interpolation data. A linear fractional description of all $\cS_{\kappa_{\rm min}}$ solutions of the (nondegenerate) problem is well known. In this paper, we present a similar result for an arbitrary $\kappa\ge \kappa_{\rm min}$.
On degenerate Hamburger moment problem and extensions of positive semidefinite Hankel block matrices
Vladimir Bolotnikov
Mathematics , 2008,
Abstract: In this paper we consider two related objects: singular positive semidefinite Hankel block--matrices and associated degenerate truncated matrix Hamburger moment problems. The description of all solutions of a degenerate matrix Hamburger moment problem is given in terms of a linear fractional transformation. The case of interest is the Hamburger moment problem whose Hankel block--matrix admits a positive semidefinite Hankel extension.
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