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951.
邹清明  朱仲义 《应用数学》2007,20(3):574-580
本文在文[7]已求得未知参数MLEs的基础上,利用条件期望方法,研究了具有Rao简单结构多元t-模型的极大似然估计的数字特征.  相似文献   
952.
In this article, we propose a residual based reliable and efficient error estimator for the new dual mixed finite element method of the elasticity problem in a polygonal domain, introduced by M. Farhloul and M. Fortin. With the help of a specific generalized Helmholtz decomposition of the error on the strain tensor and the classical decomposition of the error on the gradient of the displacements, we show that our global error estimator is reliable. Efficiency of our estimator follows by using classical inverse estimates. The lower and upper error bounds obtained are uniform with respect to the Lamé coefficient λ, in particular avoiding locking phenomena. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005.  相似文献   
953.
An asymptotically normally distributed estimate for the expected value of a positive random variable with infinite variance is introduced. Its behavior relative to estimation using the sample mean is investigated by simulations. An example of how to apply the estimate to file-size measurements on Internet traffic is also shown.  相似文献   
954.
In this paper we generalize the calculus of the power density spectrum (PDS) of a constant-envelope spread-spectrum (CE-SS) signal obtained by means of a frequency modulation (FM) using a random pulse amplitude modulated (PAM) signal as the modulation law made by a generic pulse function. We choose two possible profile of such pulses aiming to approximate those generated by the analog circuit implementing the chaotic map and we present both analytical and numerical results that show how the pulse shape affect the PDS shape of the modulated signal.  相似文献   
955.
The sensitivity and selectivity to H2 of a new In203-based gas sensor were improved significantly by surface chemical modification. A dense layer of SiO2 near the surface of the porous In2O3 bead was formed by chemical vapor deposition (CVD) of diethoxydimethysilane (DEMS). The dense layer functioned as a molecular sieve, thereby the diffusion of gases with large molecular diameters, except for 1-12, was effectively controlled, resulting in a prominent selectivity and high sensitivity for H2. The working mechanism of the sensor was also presented.  相似文献   
956.
957.
This paper gives an overview of those aspects of simulation methodology that are (to some extent) peculiar to the simulation of queueing systems. A generalized semi-Markov process framework for describing queueing systems is used through much of the paper. The main topics covered are: output analysis for simulation of transient and steady-state quantities, variance reduction methods that exploit queueing structure, and gradient estimation methods for performance parameters associated with queueing networks.The research of this author was supported by the U.S. Army Research Office under Contract DAAG29-84-K-0030.The research of this author was supported by the U.S. Army Research Office under Contract DAAG29-84-K-0030 and National Science Foundation Grant DCR-85-09668.  相似文献   
958.
The problem of classification of images that have a perfectly random nature is considered. We propose a new approach to solve this problem that is based on the use of the synthetic discriminant functions being synthesized to separate linearly the power spectra of random image fields to be classified. In the stage of both discriminant function synthesis and classification, the statistical technique of power spectrum estimation is employed. The realization of the proposed approach by means of a hybrid computer-optical technique is discussed, and its efficiency is illustrated by two examples of real-world texture classification.  相似文献   
959.
We have studied the problem of calculating Green's functions in three dimensional hydrodynamic gravity wave problems. A number of new expressions for these functions are presented for both finite and infinite depths. Various techniques for accelerating the convergence of some infinite series in these expressions are investigated and compared with the normal methods of evaluation. A significant improvement in the efficiency of the calculation is found using the results described in this paper.  相似文献   
960.
The symmetric derivative of a probability measure at a Lebesgue point can often be specified by an exact relation involving a regularity index. Knowledge of this index is of practical interest, for example to specify the local behavior of the measure under study and to evaluate bandwidths or number of neighbors to take into account in smoothing techniques. This index also determines local rates of convergence of estimators of particular points of curves and surfaces, like minima and maxima. In this paper, we consider the estimation of the d-dimensional regularity index. We introduce an estimator and derive the basic asymptotic results. Our estimator is inspired by an estimator proposed in Drees and Kaufmann (1998, Stochastic Processes and their Applications, 75, 149–172) in the context of extreme value statistics. Then, we show how (estimates of) the regularity index can be used to solve practical problems in nearest neighbor density estimation, such as removing bias or selecting the number of neighbors. Results of simulations are presented.  相似文献   
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