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排序方式: 共有921条查询结果,搜索用时 31 毫秒
1.
Nagendranath Mahata V. Vishwanathan 《Journal of molecular catalysis. A, Chemical》1997,120(1-3):267-270
Kinetics of vapor phase hydrogenation of phenol to cyclohexanone over Pd/MgO system has been studied in a flow microreactor under normal atmospheric pressure. The reaction rate is found to be negative order with respect to the partial pressure of phenol and has increased from −0.5 to 0.5 with increasing temperature (473 to 563 K). The apparent activation energy (Ea) of the process is found to be close to 65 kJ per mol. On the basis of kinetic results a surface mechanism is proposed. 相似文献
2.
Constructive Approximation - Let E = [–1, α] \cup [β, 1], –1 &;lt; α &;lt; β &;lt; 1, and let (pn) be orthogonal on E with respect to the weight function... 相似文献
3.
Joseph Y.-T. Leung 《Discrete Applied Mathematics》2007,155(8):945-970
We consider the problem of scheduling orders for multiple different product types in an environment with m dedicated machines in parallel. The objective is to minimize the total weighted completion time. Each product type is produced by one and only one of the m dedicated machines; that is, each machine is dedicated to a specific product type. Each order has a weight and may also have a release date. Each order asks for certain amounts of various different product types. The different products for an order can be produced concurrently. Preemptions are not allowed. Even when all orders are available at time 0, the problem has been shown to be strongly NP-hard for any fixed number (?2) of machines. This paper focuses on the design and analysis of efficient heuristics for the case without release dates. Occasionally, however, we extend our results to the case with release dates. The heuristics considered include some that have already been proposed in the literature as well as several new ones. They include various static and dynamic priority rules as well as two more sophisticated LP-based algorithms. We analyze the performance bounds of the priority rules and of the algorithms and present also an in-depth comparative analysis of the various rules and algorithms. The conclusions from this empirical analysis provide insights into the trade-offs with regard to solution quality, speed, and memory space. 相似文献
4.
The Efficient Determination Criterion (EDC) generalizes the AIC and BIC criteria and provides a class of consistent estimators
for the order of a Markov chain with finite state space. In this note, we derive rates of convergence for the EDC estimates.
*Partially supported by CNPq, CAPES/PROCAD, FAPDF/PRONEX, FINATEC and FUNPE/UnB.
**Partially supported by CAPES. 相似文献
5.
H. Sakuma T. Taniyama K. Ishii Y. Kitamoto Y. Yamazaki 《Journal of magnetism and magnetic materials》2006,300(2):284-292
The order parameter S of Fe–Pt nanoparticles is estimated from X-ray diffraction (XRD) patterns. The total intensity of a diffraction peak is obtained by Rietveld analysis as well as simply integrating the intensity. The Rietveld analysis is found to provide a plausible value of S even for a sample showing an XRD pattern with broad and overlapped peaks. Another order parameter Q, which is obtained from Mössbauer spectra, is introduced, and it is confirmed that Q is equivalent to the probability of Fe atoms being in the L10-type atomic arrangement. The coercivity of Fe–Pt nanoparticles is directly proportional to Q, while it vanishes at S=0.4, indicating that the magnetic property of Fe–Pt nanoparticles has a closer relationship to Q than S. 相似文献
6.
Suppose there is a Poisson process of points X
i
on the line. Starting at time zero, a grain begins to grow from each point X
i
, growing at rate A
i
to the left and rate B
i
to the right, with the pairs (A
i
, B
i
) being i.i.d. A grain stops growing as soon as it touches another grain. When all growth stops, the line consists of covered intervals (made up of contiguous grains) separated by gaps. We show (i) a fraction 1/e of the line remains uncovered, (ii) the fraction of covered intervals which contain exactly k grains is (k–1)/k!, (iii) the length of a covered interval containing k grains has a gamma(k–1) distribution, (iv) the distribution of the grain sizes depends only on the distribution of the total growth rate A
i
+B
i
, and other results. Similar theorems are obtained for growth processes on a circle; in this case we need only assume the pairs (A
i
, B
i
) are exchangeable. These results extend those of Daley, et al. (2000) who studied the case where A
i
=B
i
=1. Simulation results are given to illustrate the various theorems. 相似文献
7.
Wu Shengjian 《数学年刊B辑(英文版)》1994,15(4):453-462
Suppose that f(z)is a meromorphic function of order λ(0<λ<+∞)and of lower order μ in the plane.Let ρ be a positive number such that μ≤ρ≤λ.(1)If f^(l)(z)(0≤l<+∞)has p(1≤p<+∞)finite nonzero deficient valnes αi(i=1,…,p)with deficiencies δ(αi,f^(l)),then f(z)has a (0,∞)accumulative line of order ≥ρin any angular domain whose vertex is at the origin and whose magnitude is larger than max(π/ρ,2π-4/ρ ∑i=1^p arcsin √δ(αi,f^(l))/2).(2)If f(z) has only p(0<p<+∞)(0,∞),accumulative lines of order≥ρ:arg z=θk(0≤θ1<θ2<…<θp<2π,θp+1=θ1+2π),then λ≤π/ω,where ω=min I≤k≤p(θk+1-θk),provided that f^(l)(z)(0≤l<+∞)has a finite nonzero deficient value. 相似文献
8.
The best-r-point-average (BRPA) estimator of the maximizer of a regression function, proposed in Changchien (in: M.T. Chao, P.E. Cheng (Eds.), Proceedings of the 1990 Taipei Symposium in Statistics, June 28–30, 1990, pp. 63–78) has certain merits over the estimators derived through the estimation of the regression function. Some of the properties of the BRPA estimator have been studied in Chen et al. (J. Multivariate Anal. 57 (1996) 191) and Bai and Huang (Sankhya: Indian J. Statist. Ser. A. 61 (Pt. 2) (1999) 208–217). In this article, we further study the properties of the BRPA estimator and give its convergence rate under some quite general conditions. Simulation results are presented for the illustration of the convergence rate. Some comparisons with existing estimators such as the Müller estimator are provided. 相似文献
9.
OntheEquationn=p+k~2inShortIntervals¥WangTianze(DepartmentofMathematics,HenanUniversity,Kaifeng475001)Abstract:DenotebyE(X,Y)?.. 相似文献