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481.
吴治隆 《电子科技大学学报(社会科学版)》1996,(5)
应用Nyquist准则和Rouche定理,从研究系统特征多项式在复平面的Nyquist围线内零、极点的分布,提出一种证明Routh判据的不同方法,通过代数运算,揭示了Routh表任意相邻二阵列对应的多项式在右半复平面的零点数之差值与该相邻二阵列首列元素之比的符号之间的关系。因而这种证明既简单,物理意义又十分显然 相似文献
482.
Equally spaced designs are compared using the generalized variance as a measure of efficiency. Results for polynomial models are derived on the increased efficiency arising from increasing the number of design points when the regions are fixed and when the regions are expanded. The effects of dependence among the observations on these results are studied by considering a particular family of stationary correlated error structures. 相似文献
483.
郁定国 《绍兴文理学院学报》1994,(6)
对基于节点组(1,4)的修改的(0;1;2)插值多项式Qn(f,x)的收敛性,本文改进了Akhlaghi的结果,也即对于[-1,1]上的r(≥2)次连续可微函数f(x),当n≥4/3(r+2)时,成立|f(x)-Qn(f,x)|=O(1)n~(2-r)ω(f~(r),1/n),x∈[-1,1] 相似文献
484.
485.
A fully polynomial time approximation scheme (FPTAS) is presented for the classical 0-1 knapsack problem. The new approach considerably improves the necessary space requirements. The two best previously known approaches need O(n + 1/3) and O(n · 1/) space, respectively. Our new approximation scheme requires only O(n + 1/2) space while also reducing the running time. 相似文献
486.
Let D = (V, A) be a directed graph, for each vertex v V, let +(v) and – (v) denote the sets of arcs leaving and entering v,
and
be intersecting families on +(v) and –(v), respectively, and
and
be submodular functions on intersecting pairs. A flow f : A R is feasible if
Given a cost function c on A, the minimum cost polymatroidal flow problem is to find a feasible flow f with minimum cost {c(e)f(e)ve A}, it is a significant generalization of many combinatorial optimization problems.Given a feasible flow f*, cost and restriction functions on A, the inverse polymatroidal flow problem is to modify c, optimally and with bounds, such that f* becomes a minimum cost polymatroidal flow under the modified cost.It is shown in this paper that the inverse problem can be formulated as a combinatorial linear program and can be further transformed into a minimum cost circulation problem. Hence it can be solved efficiently by strongly polynomial combinatorial algorithms. We also give a necessary and sufficient condition for the feasibility of the inverse problem. 相似文献
487.
资源受限项目调度问题(简称RCPSP)是最具代表性的项目调度问题之一,调度过程可理解为,将受资源约束的平行工序调整为顺序工序。本文针对实际中广泛存在的资源局域、而非全局受限的情况,研究局域性RCPSP,并重点考虑一类问题:项目某环节的一系列平行工序,可用资源量只有一半,各资源可重复利用且具有相应多功能,但最多能承担2个工序,需将这些工序两两排列成对,实现项目工期最短。本文首先探索问题“局域性”特征,量化局域调度对项目工期的影响;基于此,构建只涵盖“局域调度工序”的0-1规划模型;再者,发展整数规划强对偶理论,结合Dangzig-Wolfe分解等方法,提出多项式时间的精确算法;最后通过算例测试,验证算法优势,例如,计算大规模算例的最优解,运用该算法比常规精确方法可快数万倍以上。 相似文献
488.
Renzo Fernández Cristian L. Bayes Luis Valdivieso 《Journal of Statistical Computation and Simulation》2018,88(10):1936-1957
AbstractIn this article we propose a new mixed-effects regression model for fractional bounded response variables. Our model allows us to incorporate covariates directly to the expected value, so we can quantify exactly the influence of these covariates in the mean of the variable of interest rather than to the conditional mean. Estimation is carried out from a Bayesian perspective. Due to the complexity of the augmented posterior distribution, we use a Hamiltonian Monte Carlo algorithm, the No-U-Turn sampler, implemented using the Stan software. A simulation study was performed showing that our model has a better performance than other traditional longitudinal models for bounded variables. Finally, we applied our beta-inflated mean mixed-effects regression model to real data which consists of utilization of credit lines in the peruvian financial system. 相似文献
489.
Measurement error, the difference between a measured (observed) value of quantity and its true value, is perceived as a possible source of estimation bias in many surveys. To correct for such bias, a validation sample can be used in addition to the original sample for adjustment of measurement error. Depending on the type of validation sample, we can either use the internal calibration approach or the external calibration approach. Motivated by Korean Longitudinal Study of Aging (KLoSA), we propose a novel application of fractional imputation to correct for measurement error in the analysis of survey data. The proposed method is to create imputed values of the unobserved true variables, which are mis-measured in the main study, by using validation subsample. Furthermore, the proposed method can be directly applicable when the measurement error model is a mixture distribution. Variance estimation using Taylor linearization is developed. Results from a limited simulation study are also presented. 相似文献