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无线传感器网络传输可靠性计算   总被引:2,自引:0,他引:2  
无线传感器网络是由传感器节点和汇聚节点组成的以数据为中心的无线网络.汇聚节点根据一个或多个源节点传送的采集数据对事件进行监测和判断,而数据传输的可靠性直接影响到监测和判断的准确性.在无线传感器网络中,一方面,网络拓扑结构是动态变化的,数据传输的可靠性与网络拓扑结构有关;另一方面,网络中的传感器节点是能最受限的,因此传输的可靠性还与节点的能昔密切相关-针对无线传感器网络的特点,给出了无线传感器网络的传输可靠性概念,提出一种传输可靠性度量,分别在有数据融合和无数据融合两种情况下,对网络节点的能耗情况进行了分析,获得r网络节点正常工作的概率随时间的变化关系,并导出数学表达式,用于计算节点所产生的数据包成功传输给汇聚节点的概率,从而获得了求整个网络传输可靠性的计算方法.  相似文献
2.
关于非线性不等式组Levenberg-Marquardt算法的收敛性(英文)   总被引:1,自引:1,他引:0  
本文研究了一类非线性不等式组的求解问题.利用一列目标函数两次可微的参数优化问题来逼近非线性不等式组的解,光滑Levenberg-Marquardt方法来求解参数优化问题,在一些较弱的条件下证明了文中算法的全局收敛性,数值实例显示文中算法效果较好.  相似文献
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Given any nonnegative matrix $A \in \mathbb{R}^{m \times n}$ , it is always possible to express A as the sum of a series of nonnegative rank-one matrices. Among the many possible representations of A, the number of terms that contributes the shortest nonnegative rank-one series representation is called the nonnegative rank of A. Computing the exact nonnegative rank and the corresponding factorization are known to be NP-hard. Even if the nonnegative rank is known a priori, no simple procedure exists presently that is able to perform the nonnegative factorization. Based on the Wedderburn rank reduction formula, this paper proposes a heuristic approach to tackle this difficult problem numerically. Starting with A, the idea is to recurrently extrat, whenever possible, a rank-one nonnegative portion from the previous matrix while keeping the residual nonnegative and lowering its rank by one. With a slight modification for symmetry, the method can equally be applied to another important class of completely positive matrices. No convergence can be guaranteed, but repeated restart might help alleviate the difficulty. Extensive numerical testing seems to suggest that the proposed algorithm might serve as a first-step numerical means for exploring the intriguing problem of nonnegative rank factorization.  相似文献
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The continuation methods are efficient methods to trace solution curves of nonlinear systems with parameters, which are common in many fields of science and engineering. Existing continuation methods are unstable for some complicated cases in practice, such as the case that solution curves are close to each other or the case that the curve turns acutely at some points. In this paper, a more robust corrector strategy—sphere corrector is presented. Using this new strategy, combining various predictor strategies and various iterative methods with local quadratic or superlinear convergence rates, robust continuation procedures for tracing curves are given. When the predictor steplength is no more than the so-called granularity of solution curves, our procedure of tracing solution curve can avoid “curve-jumping” and trace the whole solution curve successfully. Numerical experiments illustrate our method is more robust and efficient than the existing continuation methods.  相似文献
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自1978年改革开放以来,中国国内生产总值连续高速增长.基于对1978-2008年共31年来中国国内生产总值、固定资产投资、能源消费总量、进出口贸易总额、居民消费、人口数、财政收入等因素的关系研究,提出一个更为合适的对数线性模型,同时给出了该模型中参数的估计方法.研究表明:截止至2008年,中国国内生产总值的增长是不均衡的,而是分阶段的,而且在不同阶段,影响国内生产总值的因素有所不同,并且从经济学角度对所建立的模型给出了合理的解释,结论符合中国实际.  相似文献
6.
在声纳和雷达信号处理中,需要求解一类维数可变的非线性方程组,这类方程组具有混合三角多项式方程组形式.由于该问题有很多解,且其对应的最小二乘问题有很多局部极小点,用牛顿法等传统的迭代法很难找到有物理意义的解.若把它化为多项式方程组,再用解多项式方程组的符号计算方法或现有的同伦方法求解,由于该问题规模太大而不能在规定的时间内求解,而当考虑的问题维数较大时,利用已有的方法甚至根本无法求解.综合利用我们提出的解混合三角多项式方程组的混合同伦方法和保对称的系数参数同伦方法,我们给出该类问题一种有效的求解方法.利用这种方法,可以达到实时求解的目的,满足实际问题的需要.  相似文献
7.
We identify and study an LDG-hybridizable Galerkin method, which is not an LDG method, for second-order elliptic problems in several space dimensions with remarkable convergence properties. Unlike all other known discontinuous Galerkin methods using polynomials of degree for both the potential as well as the flux, the order of convergence in of both unknowns is . Moreover, both the approximate potential as well as its numerical trace superconverge in -like norms, to suitably chosen projections of the potential, with order . This allows the application of element-by-element postprocessing of the approximate solution which provides an approximation of the potential converging with order in . The method can be thought to be in between the hybridized version of the Raviart-Thomas and that of the Brezzi-Douglas-Marini mixed methods.

  相似文献

8.
In the past decade or so, semi-definite programming (SDP) has emerged as a powerful tool capable of handling a remarkably wide range of problems. This article describes an innovative application of SDP techniques to quadratic inverse eigenvalue problems (QIEPs). The notion of QIEPs is of fundamental importance because its ultimate goal of constructing or updating a vibration system from some observed or desirable dynamical behaviors while respecting some inherent feasibility constraints well suits many engineering applications. Thus far, however, QIEPs have remained challenging both theoretically and computationally due to the great variations of structural constraints that must be addressed. Of notable interest and significance are the uniformity and the simplicity in the SDP formulation that solves effectively many otherwise very difficult QIEPs.  相似文献
9.
许多科学与工程领域,我们经常需要求混合三角多项式方程组的全部解.一般来说,混合三角多项式方程组可以通过变量替换及增加二次多项式转化为多项式方程组,进而利用数值方法进行求解,但这种转化会增大问题的规模从而增加计算量.在本文中,我们不将问题转化,考虑利用直接同伦方法求解,并给出基于GBQ方法构造的初始方程组及同伦定理的证明.数值实验结果表明我们构造的直接同伦方法较已有的直接同伦方法更加有效.  相似文献
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