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41.
透射式GaAs光电阴极的X射线衍射研究 总被引:1,自引:1,他引:0
本文介绍了高精度多晶多反射X射线衍射仪的一种新的应用.首次将其应用于研究高灵敏度第三代微光象增强器中由掺Zn的p型GaAs/GaAlAs、玻璃组成的光电阴极的材料特性;发展了用倒格子空间衍射图方法评价光电阴级组件晶体质量的方法.通过分析得知,衍射强度在倒格子空间沿。方向展宽主要起因于晶体中的嵌镶效应的增强.文中采用衍射动力学理论的计算方法并忽略初始条件,模拟后得到的曲线与衍射强度沿ω/θ方向的投影强度曲线符合的比较好.粘接良好的阴极样品表明,GaAs/GaAlAs晶格常数的变化基本上可以消除,但粘接引起的嵌镶效应的增强却不能完全消除. 相似文献
42.
一类Schrodinger方程的周期解和谱方法 总被引:1,自引:0,他引:1
本文利用半群理论讨论了一类非线性非自共轭Schrodinger方程周期初边值解的存在唯一性,以及它的Fourier谱方法的可解性,稳定性和收敛性 相似文献
43.
44.
Cooper对质心定向运动速度的空间分布规律及“邻近效应” 总被引:3,自引:0,他引:3
在零场下 ,由超导电流密度的两种表达形式 ,导出了超导载流子质心定向运动速度的空间分布规律 ,并由毕萨定律定性地解释了“邻近效应” 相似文献
45.
《Set-Valued Analysis》2008,16(2-3):199-227
The paper contains two groups of results. The first are criteria for calmness/subregularity for set-valued mappings between
finite-dimensional spaces. We give a new sufficient condition whose subregularity part has the same form as the coderivative
criterion for “full” metric regularity but involves a different type of coderivative which is introduced in the paper. We
also show that the condition is necessary for mappings with convex graphs. The second group of results deals with the basic
calculus rules of nonsmooth subdifferential calculus. For each of the rules we state two qualification conditions: one in
terms of calmness/subregularity of certain set-valued mappings and the other as a metric estimate (not necessarily directly
associated with aforementioned calmness/subregularity property). The conditions are shown to be weaker than the standard Mordukhovich–Rockafellar
subdifferential qualification condition; in particular they cover the cases of convex polyhedral set-valued mappings and,
more generally, mappings with semi-linear graphs. Relative strength of the conditions is thoroughly analyzed. We also show,
for each of the calculus rules, that the standard qualification conditions are equivalent to “full” metric regularity of precisely
the same mappings that are involved in the subregularity version of our calmness/subregularity condition.
The research of Jiří V. Outrata was supported by the grant A 107 5402 of the Grant Agency of the Academy of Sciences of the
Czech Republic. 相似文献
46.
47.
The k-server problem is a fundamental online problem where k mobile servers should be scheduled to answer a sequence of requests for points in a metric space as to minimize the total movement cost. While the deterministic competitive ratio is at least k, randomized k-server algorithms have the potential of reaching o(k)-competitive ratios. Prior to this work only few specific cases of this problem were solved. For arbitrary metric spaces, this goal may be approached by using probabilistic metric approximation techniques. This paper gives the first results in this direction, obtaining o(k)-competitive ratio for a natural class of metric spaces, including d-dimensional grids, and wide range of k. 相似文献
48.
Annalisa Baldi 《Journal of Mathematical Analysis and Applications》2008,340(1):197-208
In this note, a classical extension result for BV functions due to Yu.D. Burago and V.G. Maz'ja [Yu.D. Burago, V.G. Maz'ja, Potential Theory and Function Theory for Irregular Regions, Seminars in Math., vol. 3, V.A. Steklov Math. Inst., Leningrad, 1969 (translated from Russian)] is generalized to the abstract setting of doubling metric measure spaces endowed with a differentiation structure called D-structure. 相似文献
49.
Read-once functions have gained recent, renewed interest in the fields of theory and algorithms of Boolean functions, computational learning theory and logic design and verification. In an earlier paper [M.C. Golumbic, A. Mintz, U. Rotics, Factoring and recognition of read-once functions using cographs and normality, and the readability of functions associated with partial k-trees, Discrete Appl. Math. 154 (2006) 1465-1677], we presented the first polynomial-time algorithm for recognizing and factoring read-once functions, based on a classical characterization theorem of Gurvich which states that a positive Boolean function is read-once if and only if it is normal and its co-occurrence graph is P4-free.In this note, we improve the complexity bound by showing that the method can be modified slightly, with two crucial observations, to obtain an O(n|f|) implementation, where |f| denotes the length of the DNF expression of a positive Boolean function f, and n is the number of variables in f. The previously stated bound was O(n2k), where k is the number of prime implicants of the function. In both cases, f is assumed to be given as a DNF formula consisting entirely of the prime implicants of the function. 相似文献
50.
Randomized approximation of Sobolev embeddings, III 总被引:1,自引:1,他引:0
We continue the study of randomized approximation of embeddings between Sobolev spaces on the basis of function values. The source space is a Sobolev space with nonnegative smoothness order; the target space has negative smoothness order. The optimal order of approximation (in some cases only up to logarithmic factors) is determined. Extensions to Besov and Bessel potential spaces are given and a problem recently posed by Novak and Woźniakowski is partially solved. The results are applied to the complexity analysis of weak solution of elliptic PDE. 相似文献