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31.
Frank E. Curtis Nicholas I.M. Gould Hao Jiang Daniel P. Robinson 《Optimization methods & software》2016,31(1):157-186
In this paper, we consider augmented Lagrangian (AL) algorithms for solving large-scale nonlinear optimization problems that execute adaptive strategies for updating the penalty parameter. Our work is motivated by the recently proposed adaptive AL trust region method by Curtis et al. [An adaptive augmented Lagrangian method for large-scale constrained optimization, Math. Program. 152 (2015), pp. 201–245.]. The first focal point of this paper is a new variant of the approach that employs a line search rather than a trust region strategy, where a critical algorithmic feature for the line search strategy is the use of convexified piecewise quadratic models of the AL function for computing the search directions. We prove global convergence guarantees for our line search algorithm that are on par with those for the previously proposed trust region method. A second focal point of this paper is the practical performance of the line search and trust region algorithm variants in Matlab software, as well as that of an adaptive penalty parameter updating strategy incorporated into the Lancelot software. We test these methods on problems from the CUTEst and COPS collections, as well as on challenging test problems related to optimal power flow. Our numerical experience suggests that the adaptive algorithms outperform traditional AL methods in terms of efficiency and reliability. As with traditional AL algorithms, the adaptive methods are matrix-free and thus represent a viable option for solving large-scale problems. 相似文献
32.
电子称量系统在各个称量领域的应用极为广泛,而桥式称重传感器是电子称量系统的核心元器件。一体化小桥式称重传感器是将底座与弹性体合为一体来大大缩小传感器的几何形体,并将传感器的自重大幅度降低的一种设计方法。这样更便于电子称量系统的安装和维护,缩短电子称量系统的安装和维护周期。 相似文献
33.
针对现有车辆监控系统难以满足大规模负载的问题,设计一款高性能的通信服务器。该通信服务器合理地划分业务结构,并从多线程异步接收、协议解析模式、共享数据同步和线程池4个方面进行优化设计。最终测试表明,该通信服务器具有良好的适用性、可靠性和可拓展性。 相似文献
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该文针对集成方法实现支持向量机大规模训练的相关问题进行了深入研究,提出了一种称为"DD-Boosting"的成员分类器产生算法,能够在大规模数据集情况下利用类似Boosting技术产生稳定、高泛化性能的成员分类器。在此基础上,推导出基于OCSVM的分类器集成模型,实验仿真表明,该集成模型能够获得比主投票方法更好的泛化性能,且通过调整正则参数避免了训练过拟合问题。 相似文献
36.
新的大尺寸截面配对式视觉测量方法的研究 总被引:1,自引:0,他引:1
根据大尺寸测量系统的现状,从分析线结构光入手,提出了组建传感器对测量方法,使每对传感器具备差动测量能力,提高单点测量精度;利用坐标测量臂和激光跟踪仪的大尺寸测量能力,对传感器坐标系进行全局校准,提高校准的精度和效率;研究椭圆检测算法,提出利用椭圆平行弦中点连线必过椭圆中心基本定理,求出椭圆中心坐标,拟合出椭圆形状;通过理论分析,该方法切实可行。 相似文献
37.
According to the classic harmonic approach, an orientation density function (odf)f is expanded into its corresponding Fourier orthogonal series with respect to generalized spherical harmonics, and a pole density function (pdf)
into its corresponding Fourier orthogonal series with respect to spherical harmonics. While pdfs are even (antipodally symmetric) functions, odfs are generally not. Therefore, the part
of the odf which cannot be determined from normal diffraction pdfs can be mathematically represented as the odd portion of its series expansion. If the odff is given, the even part
can be mathematically represented explicitly in terms off itself. Thus, it is possible to render maps ofharmonic orientation ghosts, and to evaluatevariants of mathematical standard odfs resulting in identical pdfs independent of pdf data. However, if only normal diffraction pdfs are known, the data-dependentvariation width of feasible odfs remained unaccessible, and within the harmonic approach a measure of confidence in a solution of the pdf-to-odf inversion problem does not exist.According to any discrete approach, an odff defined on some setG of orientations is expanded into its corresponding Fourier orthogonal series with respect to indicator functions of the elements of a partition ofG, and a pdf
defined on the upper (lower) unit hemisphereS
+
3
3 into its corresponding Fourier orthogonal series with respect to indicator functions of the elements of a partition ofS
+
3
. The ambiguity of the pdf-to-odf inversion problem is discussed in terms of column-rank deficiency of the augmented projection matrix. The implication of the harmonic approach to split an odf into auniquely determined and anundetermined part does no longer seem to be reasonable. However, it is possible to numerically determine data-dependent confidence intervals for the Fourier coefficients with respect to the indicator functions which can be immediately interpreted as mean orientation densities within the elements of the partition ofG. Doing so for all Fourier coefficients in the finite series expansion, i.e. for all elements of the partition of the setG, eventually results in the data-dependent variation width of odfs feasible with respect to given pdf data, and to the partitions ofG andS
+
3
.Thus it is confirmed that the appearance of orientation ghosts, in particular correlations oftrue andghost orientation components, depends on the representation of an odf. It may be questioned whether in practical applications the implicit assumption of the harmonic method that the even part
can be determined uniquely and free of error is generally a reasonable initial condition to develop ghost correction procedures. 相似文献
38.
Danyang Zhao Xiaoying Wang Wenming Zhang Yijing Zhang Yu Lei Xintang Huang Qiancheng Zhu Jinping Liu 《Advanced functional materials》2023,33(13):2211412
Aqueous Zn-ion batteries (AZIBs) are promising due to their high theoretical energy density and intrinsic safety, and the natural abundance of Zn. Since low voltage is an intrinsic shortage of AZIBs, achieving super-high capacity of cathode materials is a vital way to realize high practical energy density, which however remains a huge challenge. Herein, the capacity increase of classical vanadium oxide cathode is predicted via designing atomic thickness of 2D structure to introduce abundant Zn2+ storage sites based on density functional theory (DFT) calculation; then graphene-analogous V2O5·nH2O (GAVOH) with only few atomic layers is fabricated, realizing a record capacity of 714 mAh g−1. Pseudocapacitive effect is unveiled to mainly contribute to the super-high capacity due to the highly exposed GAVOH external surface. In situ Raman and synchrotron X-ray techniques unambiguously uncover the Zn2+ storage mechanism. Carbon nanotubes (CNTs) are further introduced to design GAVOH-CNTs gel ink for large-scale cathode fabrication. The hybrid cathode demonstrates ultra-stable cycling and excellent rate capability and delivers a high energy density of 476 Wh kg−1 at 76 W kg−1; 228 Wh kg−1 is still retained at high mass loading of 10.2 mg cm−2. This work provides inspiration for breaking the capacity limit of cathode in AZIBs. 相似文献
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