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71.
72.
Multiband frequency domain synthesis consists in the minimization of a finite family of closed-loop transfer functions on prescribed frequency intervals. This is an algorithmically difficult problem due to its inherent nonsmoothness and nonconvexity. We extend our previous work on nonsmooth H∞ synthesis to develop a nonsmooth optimization technique to compute local solutions to multiband synthesis problems. The proposed method is shown to perform well on illustrative examples. 相似文献
73.
This article is about testing the equality of several normal means when the variances are unknown and arbitrary, i.e., the set up of the one-way ANOVA. Even though several tests are available in the literature, none of them perform well in terms of Type I error probability under various sample size and parameter combinations. In fact, Type I errors can be highly inflated for some of the commonly used tests; a serious issue that appears to have been overlooked. We propose a parametric bootstrap (PB) approach and compare it with three existing location-scale invariant tests—the Welch test, the James test and the generalized F (GF) test. The Type I error rates and powers of the tests are evaluated using Monte Carlo simulation. Our studies show that the PB test is the best among the four tests with respect to Type I error rates. The PB test performs very satisfactorily even for small samples while the Welch test and the GF test exhibit poor Type I error properties when the sample sizes are small and/or the number of means to be compared is moderate to large. The James test performs better than the Welch test and the GF test. It is also noted that the same tests can be used to test the significance of the random effect variance component in a one-way random model under unequal error variances. Such models are widely used to analyze data from inter-laboratory studies. The methods are illustrated using some examples. 相似文献
74.
Alan M. Polansky 《Computational statistics & data analysis》2007,51(12):6013-6026
Markov chains provide a flexible model for dependent random variables with applications in such disciplines as physics, environmental science and economics. In the applied study of Markov chains, it may be of interest to assess whether the transition probability matrix changes during an observed realization of the process. If such changes occur, it would be of interest to estimate the transitions where the changes take place and the probability transition matrix before and after each change. For the case when the number of changes is known, standard likelihood theory is developed to address this problem. The bootstrap is used to aid in the computation of p-values. When the number of changes is unknown, the AIC and BIC measures are used for model selection. The proposed methods are studied empirically and are applied to example sets of data. 相似文献
75.
An NP-hard production–distribution problem for one product over a multi-period horizon is investigated. The aim is to minimize total cost taking production setups, inventory levels and distribution into account. An integer linear model is proposed as a compact problem specification but it cannot be solved to optimality for large instances. Instead of using a classical two-phase approach (production planning and then route construction for each day), metaheuristics that simultaneously tackle production and routing decisions are developed: a GRASP (greedy randomized adaptive search procedure) and two improved versions using either a reactive mechanism or a path-relinking process. These algorithms are evaluated on 90 randomly generated instances with 50, 100 and 200 customers and 20 periods. The results confirm the interest of integrating production and distribution decisions, compared to classical two-phase methods. Moreover, reaction and path-relinking give better results than the GRASP alone. 相似文献
76.
In this paper, bounded-real conditions for affine nonlinear state-delayed systems are derived using the concept of dissipativeness. Necessary and sufficient conditions for the system to be dissipative and to have finite L2-gain also referred to as the bounded-real condition are given. The implications on the stability of the system and feedback interconnections of such systems are also considered. Finally, an equivalent of the positive-real lemma is derived and its implications on stability of the system and feedback interconnections of such systems are similarly discussed. 相似文献
77.
Guochang Wang 《Computational statistics & data analysis》2012,56(3):587-601
Functional linear regression has been widely used to model the relationship between a scalar response and functional predictors. If the original data do not satisfy the linear assumption, an intuitive solution is to perform some transformation such that transformed data will be linearly related. The problem of finding such transformations has been rather neglected in the development of functional data analysis tools. In this paper, we consider transformation on the response variable in functional linear regression and propose a nonparametric transformation model in which we use spline functions to construct the transformation function. The functional regression coefficients are then estimated by an innovative procedure called mixed data canonical correlation analysis (MDCCA). MDCCA is analogous to the canonical correlation analysis between two multivariate samples, but is between a multivariate sample and a set of functional data. Here, we apply the MDCCA to the projection of the transformation function on the B-spline space and the functional predictors. We then show that our estimates agree with the regularized functional least squares estimate for the transformation model subject to a scale multiplication. The dimension of the space of spline transformations can be determined by a model selection principle. Typically, a very small number of B-spline knots is needed. Real and simulation data examples are further presented to demonstrate the value of this approach. 相似文献
78.
全球传统石化能源耗竭及气候变迁等负面效应日益严重,以永续发展为目标,再生能源之开发利用备受关注,已成为世界各国能源政策的主要施政方针,其中多以立法手段积极推动.综观各国已提出亦或正在施行的政策和措施,皆由订定法令来体现,以法律的形式确立发展目标,再透过具体而明确的强制规范或经济激励措施,进而得其实质成效.德国再生能源法相关法规范即为明证.德国于2000年制定全球首部再生能源优先法(Gesetz fürden Vorrang Erneuerbarer Energien),简称再生能源法(Ernererbare-Energien-Gesetz,EEG),至今已历多次修法.本文将从德国再生能源法制探讨,观其核心固定电价制度(Feed-in Tariff,FIT)与近年修法方向,说明德国再生能源产业发展之背景及现况,希祈能就推动发展再生能源有所帮助. 相似文献
79.
光(电)成像系统的特性会引起图象降质,但如果能够根据系统的传递函数确定其逆滤波函数,就可以对这种降质图象进行一定的恢复.为此,提出了一种用多项式近似的图象逆滤波的图象恢复方法,该方法就是首先将连续的逆滤波函数按泰勒级数展开,并用多项式来近似表示,通过对用多项式表达的用于图象恢复的逆滤波函数作反傅里叶变换,就可得到恢复图象在空间域中的近似运算公式,该运算是图象信号及其各阶导数的线性组合,而不是复杂的反卷积操作.同时还详细分析了方法的原理,并推导了算法公式,最后给出了空移不变和移变系统图象的恢复处理结果.实验表明,该方法特别适合于空间移变系统降质图象的恢复,如场曲恢复. 相似文献
80.
In this paper the conjugate fluid flow and energy transport problem (involving conduction-convection-radiation heat transfer) resulting from the Czochralski crystal growth process is analysed. The solidifying material is treated as a pure and semitransparent substance with material properties depending neither on temperature nor on the wavelength. The solution of the problem is obtained iteratively using two computer codes: FLUENT, a commercial CFD package, and BEM-based in-house code capable of analysing the radiative heat transfer in the entire computational domain.Obtained results not only show velocity field and temperature distribution within the bodies under consideration but also demonstrate the influence of thermal radiation on these quantities. 相似文献