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991.
Tanya Tsoncheva Mika Linden Jessica Rosenholm Christo Minchev 《Reaction Kinetics and Catalysis Letters》2005,86(2):275-280
Summary Ni-modifiedlarge poremesoporous silicasarecharacterized by XRD, N2physisorption and TPR with H2. Theeffectof the supportpore structure on their catalytic behaviorin methanol decomposition to H2, CO and CH4is studied. 相似文献
992.
N. T. Madhu P. K. Radhakrishnan Edna Williams W. Linert 《Journal of Thermal Analysis and Calorimetry》2005,79(1):157-161
The phenomenological, kinetic and mechanistic aspects of the nitrate, chloride, bromide and iodide complexes of cobalt(II) with 4-N-(4-antipyrylmethylidene)aminoantipyrine (AA) have been studied by TG and DTG techniques. The kinetic parameters such as activation energy, pre-exponential factor and entropy of activation were computed. The rate controlling process at all stages of decomposition is random nucleation with one nucleus on each particle (Mampel model) 相似文献
993.
Vilma Petkova Y. Pelovski I. Dombalov Kaia Tánsuaadu 《Journal of Thermal Analysis and Calorimetry》2005,80(3):701-708
Summary The free energy of the acidic ammonium sulfate is a good precondition its use as an additive or reagent for decomposition of natural phosphates on the way to obtain NPS or NPKS complex fertilizers. During our previous studies it was confirmed that as a result of thermo-mechanical treatment new solid phases are formed as a result of the phosphates decomposition. The aim of this study is to find out appropriate conditions for thermal treatment of Tunisia phosphorite with ammonium sulfate where the content of P2O5 soluble forms has its maximum. The process was investigated under dynamic thermal conditions. Structure and phase transformations of the mixtures to intermediate and final solid products are confirmed by different techniques. X-ray powder diffraction, infrared spectroscopy and electron microscopy have been applied successfully and relationship found between phase structure and thermal treatment applied. As a result of the complex studies optimal temperatures are determined. The solid products under optimal conditions contain phosphorous in soluble forms available for plants in the soil. As a final it is concluded that the final products could be used as complex mineral fertilizers. 相似文献
994.
本文给出了一个计算Adomian多项式的新算法,并将其用于求微分方程的近似 解.我们的算法比原有算法效率高,且易于在计算机上实现.我们在Maple中实现了这一 算法,并通过30多个微分方程的求解验证了新算法的有效性. 相似文献
995.
QIAN Jiang CHENG Mingsong & XU Shufang LMAM School of Mathematical Sciences Peking University Beijing China 《中国科学A辑(英文版)》2005,48(3):307-321
In this paper we present a new algorithm for the single-input pole assignment problem using state feedback. This algorithm is based on the Schur decomposition of the closed-loop system matrix, and the numerically stable unitary transformations are used whenever possible, and hence it is numerically reliable.The good numerical behavior of this algorithm is also illustrated by numerical examples. 相似文献
996.
WU Mixia & WANG Songgui College of Applied Sciences Beijing University of Technology Beijing China 《中国科学A辑(英文版)》2005,48(11):1451-1464
For the mixed effects models with balanced data, a new ordering of design matrices of random effects is defined, and then a simple formula of the spectral decomposition of covariance matrix is obtained. To compare with the two methods in literature, the decomposition can not only give the actual number of all distinct eigenvalues and their expression, but also show clearly the relationship between the design matrices of random effects and the decomposition. These results can be applied to the problems for testifying the analysis of the variance estimate being a minimum variance unbiased under all random effects models and some mixed effects models with balanced data, for finding the explicit solution of maximum likelihood equations for the general mixed effects model and for showing the relationship between the spectral decomposition estimate and the analysis of variance estimate. 相似文献
997.
In this work we are interested in a sufficiently accurate approximation of the steady-state potentials in a Metal Semiconductor
Field Effect Transistor (MESFET), which can be obtained with the so-called depletion region approximation (see [5]). We propose
a robust method based on the shape optimization techniques to analyze and compute the depletion boundary as a function of
the applied voltage and the geometry material properties of the device. During the optimization process several intermediate
direct problems are solved using the boundary element method (BEM). To accelerate the solutions of of these systems we use
a strategy of subdividing the domain into a number of smaller subdomains [11,9]. The scheme is iterative and each subdomain
is handled by a separate node in parallel. Test runs comparing the performance of the parallel with the serial code, and other
numerical discussions are presented.
AMS subject classification 65N55, 65N38, 65K10, 78A55.
A. Nachaoui: Corresponding author. 相似文献
998.
Elias Katsoulis David W. Kribs 《Transactions of the American Mathematical Society》2005,357(9):3739-3755
Based on a Wold decomposition for families of partial isometries and projections of Cuntz-Krieger-Toeplitz-type, we extend several fundamental theorems from the case of single vertex graphs to the general case of countable directed graphs with no sinks. We prove a Szego-type factorization theorem for CKT families, which leads to information on the structure of the unit ball in free semigroupoid algebras, and show that joint similarity implies joint unitary equivalence for such families. For each graph we prove a generalization of von Neumann's inequality which applies to row contractions of operators on Hilbert space which are related to the graph in a natural way. This yields a functional calculus determined by quiver algebras and free semigroupoid algebras. We establish a generalization of Coburn's theorem for the -algebra of a CKT family, and prove a universality theorem for -algebras generated by these families. In both cases, the -algebras generated by quiver algebras play the universal role.
999.
V. P. Karassiov 《Theoretical and Mathematical Physics》2005,145(3):1666-1677
We present theoretical foundations for the quantum tomography of polarization states of light fields as a method for measuring
their polarization density operator
, which characterizes only the polarization degrees of freedom of the radiation. We mainly attend to the method in which the
tomographic observables (the
“measurement instruments”) are polarizable in nature. We show that the quantum nature of this method can be adequately expressed
using the quasispectral tomographic decompositions of
in special operator bases, which are finite sums of partially orthogonal projection operators determining the probability
distributions of tomographic observables as the decomposition coefficients. We obtain the matrix versions of such “tomographic”
representations of
, in particular, by projecting them on semiclassical operator bases determining the polarization quasiprobability functions.
We briefly discuss the information aspects of the schemes considered in the paper.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 145, No. 3, pp. 344–357, December, 2005. 相似文献
1000.
A. A. Borovkov 《Siberian Mathematical Journal》2005,46(6):1020-1038
Let ξ1,ξ2,... be independent random variables with distributions F1F2,... in a triangular array scheme (F i may depend on some parameter). Assume that Eξ i = 0, Eξ i 2 < ∞, and put \(S_n = \sum {_{i = 1}^n \;} \xi _i ,\;\overline S _n = \max _{k \leqslant n} S_k\). Assuming further that some regularly varying functions majorize or minorize the “averaged” distribution \(F = \frac{1}{n}\sum {_{i = 1}^n F_i }\), we find upper and lower bounds for the probabilities P(S n > x) and \(P(\bar S_n > x)\). We also study the asymptotics of these probabilities and of the probabilities that a trajectory {S k } crosses the remote boundary {g(k)}; that is, the asymptotics of P(maxk≤n(S k ? g(k)) > 0). The case n = ∞ is not excluded. We also estimate the distribution of the first crossing time. 相似文献