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Search Results: 1 - 10 of 401327 matches for " M. Ershov "
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Noise in single quantum well infrared photodetectors
M. Ershov,A. N. Korotkov
Physics , 1997, DOI: 10.1063/1.119789
Abstract: The spectral density of current fluctuations in single quantum well infrared photodetectors is calculated using Langevin approach. The noise gain and the photocurrent gain are expressed in terms of basic transport parameters. Fluctuations of the incident photon flux are taken into account.
Theory of transient spectroscopy of multiple quantum well structures
M. Ershov,H. Ruda,A. Shik,A. G. U. Perera
Physics , 1999, DOI: 10.1063/1.370921
Abstract: A theory of the transient spectroscopy of quantum well (QW) structures under a large applied bias is presented. An analytical model of the initial part of the transient current is proposed. The time constant of the transient current depends not only on the emission rate from the QWs, as is usually assumed, but also on the subsequent carrier transport across QWs. Numerical simulation was used to confirm the validity of the proposed model, and to study the transient current on a larger time scale. It is shown that the transient current is influenced by the nonuniform distribution of the electric field and related effects, which results in a step-like behavior of the current. A procedure of extraction of the QW emission time from the transient spectroscopy experiments is suggested.
Lateral photocurrent spreading in single quantum well infrared photodetectors
Maxim Ershov
Physics , 1998, DOI: 10.1063/1.121481
Abstract: Lateral physical effects in single quantum well infrared photodetectors (SQWIPs) under non-uniform illumination over detector area are considered. These effects are due mainly to the in-plane transport of the photoinduced charge in the QW. The length of the lateral photocurrent spreading is determined by the in-plane conductivity of the carriers in the QW and characteristic time of the QW recharging, and can be as large as 10-10000 mkm. Closed-form analytical expressions for SQWIP responsivity for modulated infrared signal and modulation transfer function are obtained. Possible techniques to suppress lateral photocurrent spreading are discussed.
Golod-Shafarevich groups: a survey
Mikhail Ershov
Mathematics , 2012,
Abstract: In this paper we survey the main results about Golod-Shafarevich groups and their applications in algebra, number theory and topology.
Diagnostics of Argon Plasma Immersed into Water and Produced by a Non-Transferred ARC by Optical Emission Spectroscopy
S. Zaag,M. Sassi,J.M. Baronnet,E.A. Ershov-Pavlov
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2010.64.70
Abstract: Optical emission spectroscopy techniques based on evaluation of the plasma emission coefficients have been adopted for the measurements of plasma parameters of ARCs immersed into water and for determining potential active species and their distribution in the plasma. An electric ARC torch in argon has been considered working in non-transferred mode to produce the plasma. The resulting plasma jet is neither homogeneous nor stable one which makes it especially difficult for the OES measurements. So, the approach has been applied relying upon relative intensity of lines in the plasma total emission spectra and some general data on the plasma behaviour. The measurement results give a rather realistic picture of plasma parameters and spatial distributions of active species in the plasma jet with an admixture of water.
Negative capacitance effect in semiconductor devices
M. Ershov,H. C. Liu,L. Li,M. Buchanan,Z. R. Wasilewski,A. K. Jonscher
Physics , 1998, DOI: 10.1109/16.725254
Abstract: Nontrivial capacitance behavior, including a negative capacitance (NC) effect, observed in a variety of semiconductor devices, is discussed emphasizing the physical mechanism and the theoretical interpretation of experimental data. The correct interpretation of NC can be based on the analysis of the time-domain transient current in response to a small voltage step or impulse, involving a self-consistent treatment of all relevant physical effects (carrier transport, injection, recharging etc.). NC appears in the case of the non-monotonic or positive-valued behavior of the time-derivative of the transient current in response to a small voltage step. The time-domain transient current approach is illustrated by simulation results and experimental studies of quantum well infrared photodetectors (QWIPs). The NC effect in QWIPs has been predicted theoretically and confirmed experimentally. The huge NC phenomenon in QWIPs is due to the non-equilibrium transient injection from the emitter caused by the properties of the injection barrier and the inertia of the QW recharging.
Reduction of the Fixed Prosthesis Occlusive Surface Considering the Patient’s Age
P.E. Ershov
Sovremennye Tehnologii v Medicine , 2010,
Abstract: Aim of investigation is elaboration of the fixed prosthesis occlusive surface individual simulation method on a basis of the tooth occlusive surface age change study.Materials and methods. A three-dimensional contact scanner of the Roland DG Corporation firm, model PIX-4 was used in work. A scanning of the upper and lower jaw diagnostic plaster model 60 pairs, received in humans of the different age groups with intact dental rows and orthognathic occlusion is made. A treatment of the received data and detection of the abrasion facet area and the lateral tooth tubercle clivus divergence angle sizes were accomplished with a use of a computer 3D-program Catia 5-14 . The age changes of the second tooth occlusive surface relief are studied. The received data of a physiologic abrasion was in a basis of the fixed prosthesis occlusive surface individual simulation method creation considering the patient’s age and prevailing side of chewing.The received results of the masticatory muscle tonometry and the temporomandibular joint arthrotribography in patients with a partial loss of teeth prior and after treatment prove, that the fixed prosthesis occlusive surface individual simulation unlike a traditional method more effectively reduces the masticatory muscle contractile ability and tonic activity, and normalizes the temporomandibular joint arthrotribographic values and the masticatory muscle contractile activity asymmetry of the right and left sides.A statistical reliability of the fixed prosthesis occlusive surface individual simulation proposed method effectiveness is confirmed by the Wilcoxon and Friedman tests.
A generalization of the topological Brauer group
A. V. Ershov
Mathematics , 2003,
Abstract: In the present paper we study some homotopy invariants which can be defined by means of bundles with fiber a matrix algebra. We also introduce some generalization of the Brauer group in the topological context and show that any its element can be represented as a locally trivial bundle with a group of invertible operators in a Hilbert space as the structure group. Finally, we discuss its possible applications in the twisted $K$-theory.
Homotopy theory of bundles with fiber matrix algebra
A. V. Ershov
Mathematics , 2003,
Abstract: In the present paper we consider a special class of locally trivial bundles with fiber a matrix algebra. On the set of such bundles over a finite $CW$-complex we define a relevant equivalence relation. The obtained stable theory gives us a geometric description of the H-space structure $\BSU_\otimes$ on $\BSU$ related to the tensor product of virtual $\SU$-bundles of virtual dimension 1.
Theories of bundles with additional homotopy conditions
A. V. Ershov
Mathematics , 2008,
Abstract: In the present paper we study bundles equipped with extra homotopy conditions, in particular so-called simplicial $n$-bundles. It is shown that (under some condition) the classifying space of 1-bundles is the double coset space of some finite dimensional Lie group. We also establish some relation between our bundles and C*-algebras.
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