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81.
In this paper, we propose an original approach to the solution of Fredholm equations of the second kind. We interpret the standard Von Neumann expansion of the solution as an expectation with respect to a probability distribution defined on a union of subspaces of variable dimension. Based on this representation, it is possible to use trans-dimensional Markov chain Monte Carlo (MCMC) methods such as Reversible Jump MCMC to approximate the solution numerically. This can be an attractive alternative to standard Sequential Importance Sampling (SIS) methods routinely used in this context. To motivate our approach, we sketch an application to value function estimation for a Markov decision process. Two computational examples are also provided. 相似文献
82.
Joseph Z. Gleizer Vladislav Vekselman Shurik Yatom Joshua Felsteiner Yakov E. Krasik 《辐射效应与固体损伤》2013,168(6):389-398
Experimental results of research into a ferroelectric-plasma-source-assisted hollow anode (HA) discharge as a source of low-energy electron beams are presented. To generate electron beams, the HA auto-bias negative voltage was achieved by the discharge current flowing through the resistor connecting the HA and the grounded electrode. It is shown that this method allows reliable and reproducible generation of low-energy electron beams with electron energy of several hundreds of eV, electron current density up to several A/cm2 and pulse duration of several tens of microseconds. 相似文献
83.
Vladislav Mazur Lothar H. Ruhnke Tom. A. Warner Richard E. Orville 《Journal of Electrostatics》2013,71(4):763-768
The existing interpretation in the lightning literature, based on field measurements, defines recoil leaders as negative leaders. However recoil leaders are floating conductors, and, based on this physical assumption, they should be defined as bipolar and bidirectional leaders. This physics-based assumption has never previously been verified experimentally. Such verification, reported in this paper, has been obtained from observations of branched upward positive leaders from a tall tower using a high-speed video system synchronized with electric and magnetic field change and luminosity measurements on the ground. The analysis of these observations clearly reveals the nature of recoil and dart leaders as bidirectional and bipolar electrodeless discharges that develop from a small region along a path of the decayed channels of a previous positive leader, or a positively charged return stroke of negative CG flashes. 相似文献
84.
Kutyashev Igor B. Barkov Alexey Yu. Korotaev Vladislav Yu. Sosnovskikh Vyacheslav Ya. 《Chemistry of Heterocyclic Compounds》2019,55(6):529-540
Chemistry of Heterocyclic Compounds - A regio- and stereoselective method was developed for the synthesis of tetrahydro-4H-spiro[chromeno[3,4-c]pyrrole-1,3'-indolin]-2'-ones in 72−96%... 相似文献
85.
Abeer Alghamdi Thorben Wellbrock Prof. David J. S. Birch Dr. Vladislav Vyshemirsky Dr. Olaf J. Rolinski 《Chemphyschem》2019,20(23):3181-3185
A non-invasive intrinsic fluorescence sensing of the early stages of Alzheimer's beta amyloid peptide aggregation in the presence of copper ions is reported. By using time-resolved fluorescence techniques the formation of beta amyloid-copper complexes and the accelerated peptide aggregation are demonstrated. The shifts in the emission spectral peaks indicate that the peptides exhibit different aggregation pathways than in the absence of copper. 相似文献
86.
87.
Hugo M. Campos Vladislav V. Kravchenko 《Mathematical Methods in the Applied Sciences》2020,43(16):9448-9454
The paper extends some well-known results for analytic functions onto solutions of the Vekua equation regarding the existence and construction of the Bergman kernel and of the corresponding Bergman projection operator. 相似文献
88.
Clemens K. Blasius Niklas F. Heinrich Dr. Vladislav Vasilenko Prof. Lutz H. Gade 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16108-16111
A readily activated iron alkyl precatalyst effectively catalyzes the highly enantioselective hydroboration of N-alkyl imines. Employing a chiral bis(oxazolinylmethylidene)isoindoline pincer ligand, the asymmetric reduction of various acyclic N-alkyl imines provided the corresponding α-chiral amines in excellent yields and with up to >99 % ee. The applicability of this base metal catalytic system was further demonstrated with the synthesis of the pharmaceuticals Fendiline and Tecalcet. 相似文献
89.
Silicon based deposits were prepared by TEA CO2 pulsed laser ablation (PLA) of SiO and SiO2 targets in the atmosphere of selected gases (N2, He, Ne, Ar, Kr). These deposits possess high specific area of several hundreds m2 per gram. Owing to the high specific area, some chemical groups and hydrogen related radical were detected by means of FTIR and EPR analyses and theoretical calculations: silyl (E′ center) Si, silylen Si:, silanon SiO, POL (peroxy linkage) SiOOSi and/or NBOHC (non-bridging oxygen hole center) SiO, POR (peroxy radical) SiOO and dioxysilirane Si(O)2. In SiO2 deposits the concentration of silyl Si resp. POR SiOO was determined to be 5.8 × 1018/g resp. 6.2 × 1019/g. In SiO deposits the ratio [Si:]:[Si] = (3.1-5.7) × 1019/g: (5.3-9.8) × 1019/g was measured. Estimated concentration of [Si] in deposits was increased nearly five times in comparison with SiO target. After exposure of the SiO deposits to H2 EPR doublet with hyperfine splitting of 7.7 mT was observed. The best agreement between calculated theoretical and experimental values was found for the model [(HO)3SiO]2HSi. FTIR measurements and calculations of the silanol theoretical model clusters enabled us to discuss the chemical surroundings of the silanol and to determine the defects in the deposits. 相似文献
90.
Sami E. Varjosaari Vladislav Skrypai Sharon M. Herlugson Thomas M. Gilbert Marc J. Adler 《Tetrahedron letters》2018,59(29):2839-2843
1-Hydrosilatrane, a safe and easy-to-handle reducing reagent that can be inexpensively accessed, has been shown to reduce prochiral ketones asymmetrically in the presence of chiral 1,2-aminoalcohols with ees ranging from 8% to 86%. The best result was achieved using ephedrine as the source of chirality, which is readily commercially available. The additive can be recovered through extraction and reused without any erosion of enantioselectivity. 相似文献