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41.
Nikolai Ralev Stoyan Karabunarliev Ovanes Mekenyan Danail Bonchev Alexandru T. Balaban 《Journal of computational chemistry》1985,6(6):587-591
The computer implementation of the HOC procedures presented in Parts I, II and III of this series is based on the module principle. It contains a main program and seventeen subroutines in Fortran IV. The system is able to provide unique atom numbering and code for all kinds of chemical compounds in their tremendous variety of structures. 相似文献
42.
Alexandru I. Şchiop 《Numerische Mathematik》1973,20(3):208-212
In this paper we establish the stability of Ritz procedure in sense of Michlin and Tucker for a class of nonlinear two-point boundary value problems which has been considered by Varga, Schultz and Ciarlet in [1]. 相似文献
43.
It is well known that mass-metric tensor determinants det(G(s)) influence the equilibrium statistics and the rates of conformational transitions for polymers with constrained bond lengths and bond angles. It is now standard practice to include a Fixman-style compensating potential of the form U(c)(q(s)) proportional, variant(-k(B)T/2)ln[det(G(s))] as part of algorithms for torsional space molecular dynamics. This elegant strategy helps eliminate unwarranted biases that arise due to the imposition of holonomic constraints. However, the precise nature and extent of variation of det(G(s)) and hence ln[det(G(s))] with chain conformation and chain length has never been quantified. This type of analysis is crucial for understanding the nature of the conformational bias that the introduction of a Fixman potential aims to eliminate. Additionally, a detailed analysis of the conformational dependence of det(G(s)) will help resolve ambiguities regarding suggestions for incorporating terms related to det(G(s)) in the design of move sets in torsional space Monte Carlo simulations. In this work, we present results from a systematic study of the variation of det(G(s)) for a serial polymer with fixed bond lengths and bond angles as a function of chain conformation and chain length. This analysis requires an algorithm designed for rapid computation of det(G(s)) which simultaneously allows for a physical/geometric interpretation of the conformational dependence of det(G(s)). Consequently, we provide a detailed discussion of our adaptation of an O(n) algorithm from the robotics literature, which leads to simple recursion relations for direct evaluation of det(G(s)). Our analysis of the conformational dependence of det(G(s)) yields the following insights. (1) det(G(s)) is maximized for spatial conformers and minimized for planar conformations. (2) Previous work suggests that it is logical to expect that the conformational dependence of det(G(s)) becomes more pronounced with increase in chain length. Confirming this expectation, we provide systematic quantification of the nature of this dependency and show that the difference in det(G(s)) between spatial and planar conformers, i.e., between the maxima and minima of det(G(s)) grows systematically with chain length. Finally, we provide a brief discussion of implications of our analysis for the design of move sets in Monte Carlo simulations. 相似文献
44.
Florin P. Boca Radu N. Gologan Alexandru Zaharescu 《Communications in Mathematical Physics》2003,240(1-2):53-73
We consider a billiard in the punctured torus obtained by removing a small disk of radius >0 from the flat torus 2, with trajectory starting from the center of the puncture. In this case the phase space is given by the range of the velocity only. Let (), and respectively R(), denote the first exit time (length of the trajectory), and respectively the number of collisions with the side cushions when 2 is being identified with [0,1)2. We prove that the probability measures on [0, ) associated with the random variables and R are weakly convergent as 0+ and explicitly compute the densities of the limits.
Research partially supported by ANSTI grant C6189/2000. 相似文献
45.
Alexandru Dimca Fayçal Maaref Claude Sabbah Morihiko Saito 《Mathematische Annalen》2000,318(1):107-125
Using local cohomology and algebraic -Modules, we generalize a comparison theorem between relative de Rham cohomology and Dwork cohomology due to N. Katz, P. Monsky,
A. Adolphson and S. Sperber.
Received June 10, 1999 / Published online July 20, 2000 相似文献
46.
Alexandru Nedelcu Eric Costard Philippe Bois Xavier Marcadet 《Infrared Physics & Technology》2007,50(2-3):227-233
Recent results obtained on building blocks for future third generation infrared focal plane arrays (FPAs) are presented. Our approach concerning the FPA performance assessment and small pixels modelling is exposed. We also demonstrate the ability of the quantum well infrared photodetector technology to answer the needs for compact (20 μm pitch) polarimetric FPAs. Finally, we present our first results on mid-wave infrared detectors at wavelengths below 4.2 μm. 相似文献
47.
48.
Alexandru V. Asimit 《Insurance: Mathematics and Economics》2008,43(3):407-411
We consider an extension of the classical compound Poisson risk model, where the waiting time between two consecutive claims and the forthcoming claim are no longer independent. Asymptotic tail probabilities of the reinsurance amount under ECOMOR and LCR treaties are obtained. Simulation results are provided in order to illustrate this. 相似文献
49.
Alexandru L. Let David E. Mainwaring Colin Rix Pandiyan Murugaraj 《Journal of Non》2008,354(15-16):1801-1807
Titanium alkoxides react at room temperature with H2S to form an amorphous titanium alkoxy-sulfide precursor which can be converted to TiS2 by heat-treatment in a flowing H2S gas stream. The reaction of titanium isopropoxide (Ti(OPri)4) with H2S in n-butylamine solvent has been studied using infrared spectroscopy (FTIR), gas chromatography/mass spectroscopy (GC/MS), XRD and EDAX measurements. Based on these studies, it is shown that a partially sulfidized alkoxide precursor forms through the partial replacement of some alkoxy groups by hydrosulfide moieties. The alkoxy-hydrosulfide is believed to form following a thiolysis–condensation mechanism similar to the hydrolysis–condensation process that occurs during the oxide sol–gel reaction. The alkoxy-hydrosulfide species then undergoes complete sulfidization at 800 °C in a stream of H2S to yield pure, hexagonal TiS2 in either film or powder forms. 相似文献
50.