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151.
A comparative study of the bi‐linear and bi‐quadratic quadrilateral elements and the quadratic triangular element for solving incompressible viscous flows is presented. These elements make use of the stabilized finite element formulation of the Galerkin/least‐squares method to simulate the flows, with the pressure and velocity fields interpolated with equal orders. The tangent matrices are explicitly derived and the Newton–Raphson algorithm is employed to solve the resulting nonlinear equations. The numerical solutions of the classical lid‐driven cavity flow problem are obtained for Reynolds numbers between 1000 and 20 000 and the accuracy and converging rate of the different elements are compared. The influence on the numerical solution of the least square of incompressible condition is also studied. The numerical example shows that the quadratic triangular element exhibits a better compromise between accuracy and converging rate than the other two elements. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
152.
A misalignment fault is a kind of potential fault in double-fed wind turbines. The reasonable and effective fault prediction models are used to predict its development trend before serious faults occur, which can take measures to repair in advance and reduce human and material losses. In this paper, the Least Squares Support Vector Machine optimized by the Improved Artificial Fish Swarm Algorithm is used to predict the misalignment index of the experiment platform. The mixed features of time domain, frequency domain, and time-frequency domain indexes of vibration or stator current signals are the inputs of the Least Squares Support Vector Machine. The kurtosis of the same signals is the output of the model, and the principle of the normal distribution is adopted to set the warning line of misalignment fault. Compared with other optimization algorithms, the experimental results show that the proposed prediction model can predict the development trend of the misalignment index with the least prediction error. 相似文献
153.
Chen-Bo Cai Qing-Juan Han Li-Juan Tang Lu Xu Jian-Hui Jiang Hai-Long Wu Ru-Qin Yu 《Adsorption》2009,15(1):23-29
Through non-invasive monitoring the uptake of aniline vapor by active alumina in a differential adsorption bed (DAB) with
near-infrared diffuse reflectance spectroscopy (NIR-DRS), we have studied several features of the adsorption, including isotherm,
kinetics and the chemical state of aniline molecules in aniline-alumina system. What is perhaps more important, since the
information above is obtained synchronously, the proposed methodology could provide information about the type of adsorption
(chemical or physical adsorption), the change of chemical state of aniline in the system during the adsorption process, whether
the chemical adsorption and physical adsorption took place simultaneously, the rate of the chemical and physical adsorption,
and so on. 相似文献
154.
本文利用矩阵的奇异值分解(SVD),给出了在一流形上矩阵方程B^TXB=D的加权最小二乘对称解的通解表达式,并解决了加权最小二乘对称解的最佳逼近问题。 相似文献
155.
In location-routing problems, the objective is to locate one or many depots within a set of sites (representing customer locations or cities) and to construct delivery routes from the selected depot or depots to the remaining sites at least system cost. The objective function is the sum of depot operating costs, vehicle acquisition costs and routing costs. This paper considers one such problem in which a weight is assigned to each site and where sites are to be visited by vehicles having a given capacity. The solution must be such that the sum of the weights of sites visited on any given route does not exceed the capacity of the visiting vehicle. The formulation of an integer linear program for this problem involves degree constraints, generalized subtour elimination constraints, and chain barring constraints. An exact algorithm, using initial relaxation of most of the problem constraints, is presented which is capable of solving problems with up to twenty sites within a reasonable number of iterations. 相似文献
156.
Rudolf Beran 《Annals of the Institute of Statistical Mathematics》2008,60(4):843-864
The unknown matrix M is the mean of the observed response matrix in a multivariate linear model with independent random errors. This paper constructs
regularized estimators of M that dominate, in asymptotic risk, least squares fits to the model and to specified nested submodels. In the first construction,
the response matrix is expressed as the sum of orthogonal components determined by the submodels; each component is replaced
by an adaptive total least squares fit of possibly lower rank; and these fits are then summed. The second, lower risk, construction
differs only in the second step: each orthogonal component is replaced by a modified Efron-Morris fit before summation. Singular
value decompositions yield computable formulae for the estimators and their asymptotic and estimated risks. In the asymptotics,
the row dimension of M tends to infinity while the column dimension remains fixed. Convergences are uniform when signal-to-noise ratio is bounded.
This research was supported in part by National Science Foundation Grant DMS 0404547. 相似文献
157.
Achiya Dax 《Mathematical Programming》1986,36(1):72-80
Thekey problem of the Euclidean multifacility location (EMFL) problem is to decide whether a givendead point is optimal. If it is not optimal, we wish to compute a descent direction. This paper extends the optimality conditions of
Calamai and Conn and Overton to the case when the rows of the active constraints matrix are linearly dependent. We show that
linear dependence occurs wheneverG, the graph of the coinciding facilities, has a cycle. In this case the key problem is formulated as a linear least squares
problem with bounds on the Euclidean norms of certain subvectors. 相似文献
158.
Hiroyuki Uesaka Chooichiro Asano 《Annals of the Institute of Statistical Mathematics》1987,39(1):513-531
Summary The purpose of the present paper is to propose an analytical method for ordered categorical responses obtained from a repeated
measurement/longitudinal experiment. The ordered categorical scale is assumed to be a manifestation of a latent quantitative
variable. A linear model is assumed for location parameters of the underlying distributions. Weighted least square method
is applied to parameter estimation and subsequent analysis. Two data sets are analyzed to show several aspects of analysis
by the proposed model and to discuss comparative characteristics of analysis compared with earlier analysis. A mention is
made for a computer software program for the proposed model. 相似文献
159.
A new method for computing the topological entropy of a piecewise monotonic transformation on the interval is presented. It uses a transition matrix associated with the transformation. For this matrix we give a spectral theorem. This can be used for an estimation of the accuracy of the algorithm. 相似文献
160.
This short note proves that the least square nucleolus (Ruiz et al. (1996)) and the lexicographical solution (Sakawa and Nishizaki (1994)) select the same imputation in each game with nonempty imputation set. As a consequence the
least square nucleolus is a general nucleolus (Maschler et al. (1992)).
Received: December 1998/Revised version: July 1999 相似文献