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951.
IntroductionInFTsynthesis,metalMnhasbeenregardedasanicepromotertoincreaselightolefinselectivity.Coprecipitationhasbeenusedextensivelyinthepreparationofcommercialcatalysts.AnumberofpublicationsdealingwiththerelationbetWcenphysical-chemistry'proPertiesofcatalystsandFTs}nthesishaveappeared,butdifferentcatal})stcompositionsandpreparationconditi0nsmakedifferentconclusions.Therearetu)omainrespects.0neisthatcarelystswithhighacivityandolefinselectivityhavedifferentMMieratiovaryingoverawiderange(Mn… 相似文献
952.
René de Borst Julien Réthoré Marie-Angèle Abellan 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,75(10-12):595-606
A finite element method is proposed that can capture arbitrary discontinuities in a two-phase medium. The discontinuity is described in an exact manner by exploiting the partition-of-unity property of finite element shape functions. The fluid flow away from the discontinuity is modelled in a standard fashion using Darcy’s relation, while at the discontinuity a discrete analogon of Darcy’s relation is proposed. The results of this finite element model are independent of the original discretisation, as is demonstrated by an example of shear banding in a biaxial, plane-strain specimen. 相似文献
953.
T. K. Kwei Eli M. Pearce Fan Ren J. P. Chen 《Journal of Polymer Science.Polymer Physics》1986,24(7):1597-1609
The enthalpy–infrared frequency shift correlation for simple acids and bases is extended to study hydrogen bonding in polymer systems. The acidity of a polymer is calibrated by comparing the shifts in hydroxyl absorption frequency of the acidic polymer when mixed with a series of bases with the corresponding spectral shifts of known acids with the same bases. The basicity of a polymer is calibrated by measuring the hydroxyl frequency shifts of known acids when mixed with the basic polymer. For polymers containing carbonyl groups, the shift in carbonyl absorption is also a measure of basicity. The acidity and basicity constants obtained for polymers are in good agreement with the values for small-molecule analogs. The enthalpies of hydrogen bond formation in polymer mixtures are calculated from the acidity or basicity constants. 相似文献
954.
加工中心是高效自动化设备,为了充分利用机床的高效率、高精度、高自动化等特点,所以要考虑和了解影响加工中心加工精度的因素。 相似文献
955.
In this article ,we chiefly discuss optical part and photoelectrical part, and analyze the result data to make out the relationship between pinhole and special resolution and the influence of PMT on the result data. 相似文献
956.
An Iterative Procedure for Evaluating Digraph Competitions 总被引:1,自引:0,他引:1
A competition which is based on the results of (partial) pairwise comparisons can be modelled by means of a directed graph. Given initial weights on the nodes in such digraph competitions, we view the measurement of the importance (i.e., the cardinal ranking) of the nodes as an allocation problem where we redistribute the initial weights on the basis of insights from cooperative game theory. After describing the resulting procedure of redistributing the initial weights, an iterative process is described that repeats this procedure: at each step the allocation obtained in the previous step determines the new input weights. Existence and uniqueness of the limit is established for arbitrary digraphs. Applications to the evaluation of, e.g., sport competitions and paired comparison experiments are discussed. 相似文献
957.
Xiaofeng Ren 《Archive for Rational Mechanics and Analysis》1997,138(2):169-203
Multiple-layer solutions of the balanced bistable equation in infinite tubes are constructed via a variational method. I
start with a characterization of Palais-Smale sequences which easily gives some global minima in the desired function classes
as single layers. Assuming these minima are isolated as critical points, I paste them together to serve as an approximate
multiple-layer solution. If there were no exact solutions near the approximate one, the negative gradient flow of the energy
functional would significantly lower the energy. On the other hand, if the minima are kept far from each other, the energy
of a function near the approximate solution is not much less than that of the approximate solution. This contradiction proves
the existence of a solution.
(Accepted January 11, 1996) 相似文献
958.
René Lamour 《Numerische Mathematik》1991,59(1):815-829
Summary Consider a TPBVP for transferable nonlinear DAE's. In general the shooting equation has a singular Jacobian. A multiple shooting method which has a nonsingular Jacobian and also produces consistent initial values for the integration is presented. The estimation of the condition of the Jacobian shows the well-posedness of the method. Some illustrative examples are given 相似文献
959.
Synthetic saponites have been intercalated with hydroxyl aluminium oligomers and characterized with several techniques. The basal 001 peak of the pillared saponite (PS) is 1. 8 nm. The amount of the aluminium in the tctrahedral sheet is correlative with cross-linking density. The sheet-to-pillar linkage mode may be Si-O-AlpⅥ. The acid sites in pillared saponite may locate either at surface of clay or at that of pillar. The cumene conversion is relative to accessible acid sites on the surface of PS. The pillar density in the PS has an effect on the pore structure which is correlative with shape selectivity during the reaction between ethanol and ammonia. 相似文献
960.
ON THE EMPTY CONVEX PARTITION OF A FINITE SET IN THE PLANE 总被引:2,自引:0,他引:2
The authors discuss the partition of a finite set of points in the plane into empty convex polygons, and improve some upper bound and lower bound in the related enumeration problems. 相似文献