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161.
V. G. Ushakov N. G. Ushakov 《Moscow University Computational Mathematics and Cybernetics》2009,33(3):138-145
Algorithms for the automatic choice of the smoothing parameter in the kernel density estimation problems are proposed. These
algorithms use the behavior of the total variation of the estimate. 相似文献
162.
Andrei V. Afonin Igor A. Ushakov Alexander V. Vashchenko Dmitry E. Simonenko Andrei V. Ivanov Alexander M. Vasil'tsov Al'bina I. Mikhaleva Boris A. Trofimov 《Magnetic resonance in chemistry : MRC》2009,47(2):105-112
According to the 1H, 13C and 15N NMR spectroscopic data and DFT calculations, the E‐isomer of 1‐vinylpyrrole‐2‐carbaldehyde adopts preferable conformation with the anti‐orientation of the vinyl group relative to the carbaldehyde oxime group and with the syn‐arrangement of the carbaldehyde oxime group with reference to the pyrrole ring. This conformation is stabilized by the C? H···N intramolecular hydrogen bond between the α‐hydrogen of the vinyl group and the oxime group nitrogen, which causes a pronounced high‐frequency shift of the α‐hydrogen signal in 1H NMR (~0.5 ppm) and an increase in the corresponding one‐bond 13C–1H coupling constant (ca 4 Hz). In the Z‐isomer, the carbaldehyde oxime group turns to the anti‐position with respect to the pyrrole ring. The C? H···O intramolecular hydrogen bond between the H‐3 hydrogen of the pyrrole ring and the oxime group oxygen is realized in this case. Due to such hydrogen bonding, the H‐3 hydrogen resonance is shifted to a higher frequency by about 1 ppm and the one‐bond 13C–1H coupling constant for this proton increases by ~5 Hz. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
163.
Sergey V. Fedorov Leonid B. Krivdin Yury Yu. Rusakov Igor A. Ushakov Natalia V. Istomina Natalia A. Belogorlova Svetlana F. Malysheva Nina K. Gusarova Boris A. Trofimov 《Magnetic resonance in chemistry : MRC》2009,47(4):288-299
Theoretical energy‐based conformational analysis of bis(2‐phenethyl)vinylphosphine and related phosphine oxide, sulfide and selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6‐311G** level to study stereochemical behavior of their 31P–1H spin–spin coupling constants measured experimentally and calculated at different levels of theory. All four title compounds are shown to exist in the equilibrium mixture of two conformers: major planar s‐cis and minor orthogonal ones, while 31P–1 H spin–spin coupling constants under study are found to demonstrate marked stereochemical dependences with respect to the geometry of the coupling pathways, and to the internal rotation of the vinyl group around the P(X)‐C bonds (X = LP, O, S and Se), opening a new guide in the conformational studies of unsaturated phosphines and phosphine chalcogenides. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
164.
R. V. Kochanovich N. N. Minakova I. I. Skvirskaya V. Ya. Ushakov 《Russian Physics Journal》1998,41(6):597-599
We describe a method for estimating the breakdown characteristics of composite resistors by using models of their formulations.
Using similarity theory, we construct a quantitative model of property formation by extrapolation based on combining the variations
of similar characteristics of different materials. Input parameters in the model are the properties of the starting materials
for the resistive material, and the outputs are the required electrophysical parameters.
Tomsk Polytechnical University. Altaiskii Technical University. Translated from Izvestiya Vysshikh Uchebnykh, Zavedenii, Fizika,
No. 6, pp. 99–102, June, 1998. 相似文献
165.
166.
Dolgachev G.I. Zakatov L.P. Ushakov A.G. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(5):1410-1419
Repetitive plasma opening switch (POS) research for X-ray and electron beam generators for commercial applications is reviewed. This research was started on the RS-20 generator in 1991 with submicrosecond conduction times, 100 kA currents, and MV voltages. In the experiments wall-plug to electron beam production efficiency was increased from 10-50%. Maximum voltage obtained at POS was 3 MV starting from 0.8 MV at the Marx generator. POS operation was improved using an applied external magnetic field for the opening phase. Diode current and total generator efficiency were increased by combining the POS and diode system in one technology unit. For the opening phase of the high-impedance, repetitive POS, a set of conditions based on early POS experiments in the Kurchatov Institute were proposed. Repetitive POS generators have obtained peak X-ray dose rates of 1 MGy/s and electron dose rates of 10 GGy/s. This may be important for applications as pulsed irradiation may cause more efficient sterilization at lower doses. An X-ray generator based on repetitive POS technology at 5 MV and 200 kW in the electron beam is proposed 相似文献
167.
V. K. Kononenko H. W. Kunert I. S. Manak D. V. Ushakov 《Journal of Applied Spectroscopy》2003,70(1):115-121
Taking into account the density state tails appearing due to fluctuations of impurity concentrations, the spontaneous emission spectra of doped semiconductor superlattices are calculated. In the framework of the model developed, the explanation of the experimentally observed longwave edge and the shift of the photoluminescence spectra with increase in the excitation level and temperature is given. The role of the defects formed on -irradiation is discussed, and the lifetime of current carriers is evaluated depending on the design parameters and excitation conditions of the GaAs doped superlattices. 相似文献
168.
Wünsche HJ Bauer S Kreissl J Ushakov O Korneyev N Henneberger F Wille E Erzgräber H Peil M Elsässer W Fischer I 《Physical review letters》2005,94(16):163901
Two delay-coupled semiconductor lasers are studied in the regime where the coupling delay is comparable to the time scales of the internal laser oscillations. Detuning the optical frequency between the two lasers, novel delay-induced scenarios leading from optical frequency locking to successive states of periodic intensity pulsations are observed. We demonstrate and analyze these dynamical phenomena experimentally using two distinct laser configurations. A theoretical treatment reveals the universal character of our findings for delay-coupled systems. 相似文献
169.
170.