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41.
Voronoi diagrams and arrangements 总被引:6,自引:0,他引:6
We propose a uniform and general framework for defining and dealing with Voronoi diagrams. In this framework a Voronoi diagram is a partition of a domainD induced by a finite number of real valued functions onD. Valuable insight can be gained when one considers how these real valued functions partitionD ×R. With this view it turns out that the standard Euclidean Voronoi diagram of point sets inR
d
along with its order-k generalizations are intimately related to certain arrangements of hyperplanes. This fact can be used to obtain new Voronoi diagram algorithms. We also discuss how the formalism of arrangements can be used to solve certain intersection and union problems. 相似文献
42.
Maria Novella Romanelli Silvia Dei Serena Scapecchi Elisabetta Teodori Fulvio Gualtieri Roberta Budriesi Raimund Mannhold 《Journal of computer-aided molecular design》1994,8(2):123-134
Summary In this work the rigid-analogue approach has been used to obtain information on the active conformation(s) of the calcium antagonist verapamil. A series of semi-rigid analogues of verapamil were synthesized and their biological activities evaluated on guinea-pig heart and aorta. These molecules were analysed by means of molecular modelling techniques.On the basis of the pharmacological profile and conformational analysis of these compounds, two different models for negative inotropic and negative chronotropic activity are proposed. The two actions seem to be due to conformations of the molecules which differ in the orientation of their phenylethylamino groups. 相似文献
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In this paper we show how certain geometric convolution operations can be computed efficiently. Here efficiently means that our algorithms have running time proportional to the input size plus the output size. Our convolution algorithms rely on new optimal solutions for certain reciprocal search problems, such as finding intersections between blue and green intervals, and overlaying convex planar subdivisions.This research was done while on leave from Cornell at DEC/SRC. 相似文献
47.
Gel points in random polymerizations of the general type ΣiRA + ΣjRB in which A-groups react with A- and B-groups, and B-groups react only with A-groups are considered. (The symbols Σi and Σi signify that the A- and B-bearing reactants RA and RB can be mixtures of monomers of different functionalities, denoted generally as fai and fbj.) The usual case of A-groups reacting only with B-groups is a special case of the present theory. The effects of chemical kinetics, the competitive reaction of A- and B-groups, are separated from the generalized statistical condition for gelation. The former are used to define reaction curves and the latter, gelation curves. Both types of curve are represented as pa as a function of pb. For a given polymerization, gelation occurs when the reaction curve and the gelation curve intersect. When A-groups react only with B-groups, the gel points are those for the usual type of ΣiRA + ΣjRB polymerization, and, in the limit of A-groups only reacting with A-groups, the gel points are those for ΣiRA self polymerizations. 相似文献
48.
Raimund Bürger Hermano Frid Kenneth H. Karlsen 《Journal of Mathematical Analysis and Applications》2007,326(1):108-120
We study a zero-flux type initial-boundary value problem for scalar conservation laws with a genuinely nonlinear flux. We suggest a notion of entropy solution for this problem and prove its well-posedness. The asymptotic behavior of entropy solutions is also discussed. 相似文献
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Preparation of Trifluormethylhalogen Iodate(I) Salts (CH3)4N+CF3IX? (X = F, Cl, Br) and Trifluormethyltrifluormethoxy Iodate(I) (CH3)4N+CF3IOCF3? We describe the preparation of new trifluormethyliodate(I) salts CF3IX? (X = F, Cl, Br, OCF3). (CH3)4N+CF3ICl? and (CH3)4N+CF3IBr? are obtained via addition of CF3I with the corresponded tetramethylammonium halogenide. (CH3)4N+CF3IOCF3? is synthesized by comproportionation of (CH3)4N+CF3ICl? with CF3OCl under formation of Cl2 at ?78°C. (CH3)4N+CF3IF? is formed either, through thermolysis of (CH3)4N+ CF3IOCF3? under separation of COF2, or reaction of CF3I with (CH3)4N+ OCF3?. The thermolabile compounds have been characterized by i.r., Raman, 19F-, 13C NMR spectroscopy. 相似文献