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81.
Lukáš Šimurka Radim Čtvrtlík Jan Tomaštík Gence Bektaş Jan Svoboda Klaus Bange 《Chemical Papers》2018,72(9):2143-2151
The optical and mechanical properties of amorphous SiO2 films deposited on soda-lime silicate float glass by reactive RF magnetron sputtering at room temperature were investigated in dependence of the process pressure. The densities of the films are strongly influenced by the process pressure and vary between 2.38 and 1.91 g cm?3 as the pressure changes from 0.27 to 1.33 Pa. The refractive indices of the films shift between 1.52 and 1.37, while the residual compressive stresses in the deposited films vary in the range from 440 to 1 MPa. Hardness and reduced elastic modulus values follow the same trend and decline with the increase of process pressure from 8.5 to 2.2 GPa and from 73.7 to 30.9 GPa, respectively. The abrasive wear resistance decreases with the density of the films. 相似文献
82.
We present the numbers of all non-isomorphic residuated lattices with up to 12 elements and a link to a database of these lattices. In addition, we explore various characteristics of these lattices such as the width, length, and various properties considered in the literature and provide the corresponding statistics. We also present algorithms for computing finite residuated lattices including a fast heuristic test of non-isomorphism. 相似文献
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84.
Universal bounds for the constant in the strengthened Cauchy-Bunyakowski-Schwarz inequality for piecewise linear-linear and piecewise quadratic-linear finite element spaces in 2 space dimensions are derived. The bounds hold for arbitrary shaped triangles, or equivalently, arbitrary matrix coefficients for both the scalar diffusion problems and the elasticity theory equations. 相似文献
85.
Radim Blaheta 《Numerical Linear Algebra with Applications》1994,1(2):107-128
Two preconditioning techniques for the numerical solution of linear elasticity problems are described and studied. Both techniques are based on spectral equivalence approach. The first technique consists in an incomplete factorization of the separate displacement component part of the stiffness matrix. The second technique uses an incomplete factorization of the isotropic approximation to the stiffness matrix. Results concerning existence, stability and efficiency of these preconditioning techniques are presented. The efficiency and robustness of the described techniques are illustrated by numerical experiments. 相似文献
86.
Hrdina R Müller CE Wende RC Lippert KM Benassi M Spengler B Schreiner PR 《Journal of the American Chemical Society》2011,133(20):7624-7627
We present a new class of catalysts based on the combination of N,N'-diaryl(thio)ureas and weak silicon Lewis acids (e.g., SiCl(4)). Such silicon-(thio)urea catalysts effectively catalyze the stereospecific rearrangement of epoxides to quaternary carbaldehydes. 相似文献
87.
Hubert Hřebabecký Milan Dejmek Michal Šála Helena Mertlíková-Kaiserová Martin Dračínský Pieter Leyssen Johan Neyts Radim Nencka 《Tetrahedron》2012,68(15):3195-3204
The synthesis and antiviral evaluation of 6-amino- and 6-chloro-9-(exo-bicyclo[2.2.1]hept-2yl)-9H-purine derivatives with thiophene and tetrahydrothiophenes annelated to a norbornane moiety are described. The key step in the synthesis of derivatives with the symmetrically annelated thiophene was the Mitsunobu reaction of endo-4-thiatricyclo[5.2.1.02,6]deca-2,5-dien-8-ol with 6-chloropurine. The key alcohol was obtained by DDQ mediated aromatization of the corresponding tetrahydro derivatives, which were used for the preparation of the target tetrahydrothieno analogs. The key intermediate for the synthesis of derivatives with the asymmetrically annelated thiophene was 8-exo-azido-3-thiatricyclo[5.2.1.02,6]deca-2(6),4-diene, which was prepared from 5-exo-azido[2.2.1]heptan-2-one by aldol condensation with O-ethyl S-(2-oxoethyl) carbonodithioate, deprotection and cyclization. The target compounds were obtained by the construction of the purine base on an amine, which was obtained by LAH reduction of the key azide. The synthesized compounds were evaluated for antiviral and cytostatic activity. 相似文献
88.
We present a new approach to factor analysis of three-way binary data, i.e. data described by a 3-dimensional binary matrix I, describing a relationship between objects, attributes, and conditions. The problem consists in finding a decomposition of I into three binary matrices, an object-factor matrix A, an attribute-factor matrix B, and a condition-factor matrix C, with the number of factors as small as possible. The scenario is similar to that of decomposition-based methods of analysis of three-way data but the difference consists in the composition operator and the constraint on A, B, and C to be binary. We show that triadic concepts of I, developed within formal concept analysis, provide us with optimal decompositions. We present an example demonstrating the usefulness of the decompositions. Since finding optimal decompositions is NP-hard, we propose a greedy algorithm for computing suboptimal decompositions and evaluate its performance. 相似文献
89.
Some Properties of Residuated Lattices 总被引:1,自引:0,他引:1
Radim Bělohlávek 《Czechoslovak Mathematical Journal》2003,53(1):161-171
We investigate some (universal algebraic) properties of residuated lattices--algebras which play the role of structures of truth values of various systems of fuzzy logic. 相似文献
90.
If there are correlations between two qubits, then the results of the measurement on one of them can help to predict measurement results on the other one. It is an interesting question as to what can be predicted about the results of two complementary projective measurements on the first qubit. To quantify these predictions the complementary knowledge excesses are used. A nontrivial constraint restricting them is derived. For any mixed state and for arbitrary measurements the knowledge excesses are bounded by a factor depending only on the maximal violation of Bell's inequalities. This result is experimentally verified on two-photon Werner states prepared by means of spontaneous parametric down-conversion. 相似文献