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Two linear subpattern dimensionality reduction algorithms 被引量:1
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作者 贲晛烨 孟维晓 +1 位作者 王泽 王科俊 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2012年第5期47-53,共7页
This paper presents two novel algorithms for feature extraction-Subpattern Complete Two Dimensional Linear Discriminant Principal Component Analysis (SpC2DLDPCA) and Subpattern Complete Two Dimensional Locality Preser... This paper presents two novel algorithms for feature extraction-Subpattern Complete Two Dimensional Linear Discriminant Principal Component Analysis (SpC2DLDPCA) and Subpattern Complete Two Dimensional Locality Preserving Principal Component Analysis (SpC2DLPPCA). The modified SpC2DLDPCA and SpC2DLPPCA algorithm over their non-subpattern version and Subpattern Complete Two Dimensional Principal Component Analysis (SpC2DPCA) methods benefit greatly in the following four points: (1) SpC2DLDPCA and SpC2DLPPCA can avoid the failure that the larger dimension matrix may bring about more consuming time on computing their eigenvalues and eigenvectors. (2) SpC2DLDPCA and SpC2DLPPCA can extract local information to implement recognition. (3)The idea of subblock is introduced into Two Dimensional Principal Component Analysis (2DPCA) and Two Dimensional Linear Discriminant Analysis (2DLDA). SpC2DLDPCA combines a discriminant analysis and a compression technique with low energy loss. (4) The idea is also introduced into 2DPCA and Two Dimensional Locality Preserving projections (2DLPP), so SpC2DLPPCA can preserve local neighbor graph structure and compact feature expressions. Finally, the experiments on the CASIA(B) gait database show that SpC2DLDPCA and SpC2DLPPCA have higher recognition accuracies than their non-subpattern versions and SpC2DPCA. 展开更多
关键词 subpattern dimensionality reduction Subpattern COMPLETE TWO dimensionAL linear Discriminant Principal COMPONENT ANALYSIS (SpC2DLDPCA) Subpattern COMPLETE TWO dimensionAL Locality Preserving Principal COMPONENT ANALYSIS (SpC2DLPPCA) gait recognition
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Establishment of infinite dimensional Hamiltonian system of multilayer quasi-geostrophic flow & study on its linear stability
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作者 黄思训 王宇 项杰 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第11期300-309,共10页
A multilayer flow is a stratified fluid composed of a finite number of layers with densities homogeneous within one layer but different from each other. It is an intermediate system between the single-layer barotropic... A multilayer flow is a stratified fluid composed of a finite number of layers with densities homogeneous within one layer but different from each other. It is an intermediate system between the single-layer barotropic model and the continuously stratified baroclinic model. Since this system can simulate the baroclinic effect simply, it is widely used to study the large-scale dynamic process in atmosphere and ocean. The present paper is concerned with the linear stability of the multilayer quasi-geostrophic flow, and the associated linear stability criteria are established. Firstly, the nonlinear model is turned into the form of a Hamiltonian system, and a basic flow is defined. But it cannot be an extreme point of the Hamiltonian function since the system is an infinite-dimensional one. Therefore, it is necessary to reconstruct a new Hamiltonian function so that the basic flow becomes an extreme point of it. Secondly, the linearized equations of disturbances in the multilayer quasi-geostrophic flow are derived by introducing infinitesimal disturbances superposed on the basic flows. Finally, the properties of the linearized system are discussed, and the linear stability criteria in the sense of Liapunov are derived under two different conditions with respect to certain norms. 展开更多
关键词 infinite dimensional Hamiltonian system multilayer quasi-geostrophic flow linear stability
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Gravity effect calculation of threedimensional linear density distribution andits application
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作者 楼海 王椿镛 《Acta Seismologica Sinica(English Edition)》 EI CSCD 1999年第3期327-334,共8页
An algorithm for calculating gravity effect of three-dimensional (3D) linear density distribution is presented in this paper. The linear continuous density distribution is represented with 3D grid model, which has a ... An algorithm for calculating gravity effect of three-dimensional (3D) linear density distribution is presented in this paper. The linear continuous density distribution is represented with 3D grid model, which has a resemblance to the velocity model used in some seismic tomography codes. The consensus in representation method of density model and velocity model facilitates the seismic-gravity-integrated interpretation or simultaneous inversion. The numerical test of synthetic data shows that although the analytical gravity formula for linear density distribution is more complex than that for piecewise constant density distribution, it takes less time to calculate the gravity effect with linear density model than that with piecewise constant density model. In addition, this method is used in the integrated interpretation of 3D seismological tomography and gravity data in Dabie Mountain area. 展开更多
关键词 three-dimensional linear density distribution analytical gravity formula seismic-gravityintegrated interpretation
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Certain Algebraic Test for Analyzing Aperiodic Stability of Two-Dimensional Linear Discrete Systems
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作者 P. Ramesh 《Circuits and Systems》 2016年第6期718-725,共8页
This paper addresses the new algebraic test to check the aperiodic stability of two dimensional linear time invariant discrete systems. Initially, the two dimensional characteristics equations are converted into equiv... This paper addresses the new algebraic test to check the aperiodic stability of two dimensional linear time invariant discrete systems. Initially, the two dimensional characteristics equations are converted into equivalent one-dimensional equation. Further Fuller’s idea is applied on the equivalent one-dimensional characteristics equation. Then using the co-efficient of the characteristics equation, the routh table is formed to ascertain the aperiodic stability of the given two-dimensional linear discrete system. The illustrations were presented to show the applicability of the proposed technique. 展开更多
关键词 Routh Table Aperiodic Stability Characteristics Equation TWO-dimensionAL linear Discrete Systems
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Exact solutions and linear stability analysis for two-dimensional Ablowitz Ladik equation
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作者 张金良 王红县 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期300-309,共10页
The Ablowitz-Ladik equation is a very important model in nonlinear mathematical physics. In this paper, the hyper- bolic function solitary wave solutions, the trigonometric function periodic wave solutions, and the ra... The Ablowitz-Ladik equation is a very important model in nonlinear mathematical physics. In this paper, the hyper- bolic function solitary wave solutions, the trigonometric function periodic wave solutions, and the rational wave solutions with more arbitrary parameters of two-dimensional Ablowitz-Ladik equation are derived by using the (GI/G)-expansion method, and the effects of the parameters (including the coupling constant and other parameters) on the linear stability of the exact solutions are analysed and numerically simulated. 展开更多
关键词 two-dimensional Ablowitz-Ladik equation linear stability exact solution numerical simulation
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k-MAJOR ORDER IN REAL INFINITE-DIMENSIONAL LINEAR SPACE AND ITS APPLICATION
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作者 Lu JingkuiDept.of Basic Knowledge,Shanghai Light Industry College,Shanghai 2 0 0 4 33. 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2000年第3期302-306,共5页
In this paper,the k major cone and strict k major cone in real infinite dimensional linear space are introduced,through which the k major order is defined,and their properties are also discussed.Therefore,with the ... In this paper,the k major cone and strict k major cone in real infinite dimensional linear space are introduced,through which the k major order is defined,and their properties are also discussed.Therefore,with the help of them any two elements in real infinite dimensional linear space can be compared. 展开更多
关键词 Real infinite dimensional linear space k major cone k major order.
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A New Fourth Order Difference Approximation for the Solution of Three-dimensional Non-linear Biharmonic Equations Using Coupled Approach
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作者 Ranjan Kumar Mohanty Mahinder Kumar Jain Biranchi Narayan Mishra 《American Journal of Computational Mathematics》 2011年第4期318-327,共10页
This paper deals with a new higher order compact difference scheme, which is, O(h4) using coupled approach on the 19-point 3D stencil for the solution of three dimensional nonlinear biharmonic equations. At each inter... This paper deals with a new higher order compact difference scheme, which is, O(h4) using coupled approach on the 19-point 3D stencil for the solution of three dimensional nonlinear biharmonic equations. At each internal grid point, the solution u(x,y,z) and its Laplacian Δ4u are obtained. The resulting stencil algo-rithm is presented and hence this new algorithm can be easily incorporated to solve many problems. The present discretization allows us to use the Dirichlet boundary conditions only and there is no need to discretize the derivative boundary conditions near the boundary. We also show that special treatment is required to handle the boundary conditions. Convergence analysis for a model problem is briefly discussed. The method is tested on three problems and compares very favourably with the corresponding second order approximation which we also discuss using coupled approach. 展开更多
关键词 THREE-dimensionAL NON-linear BIHARMONIC Equation Finite Differences Fourth Order Accuracy Compact Discretization Block-Block-Tridiagonal Tangential Derivatives Laplacian Stream Function REYNOLDS Number
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基于一元线性回归模型的供水网络中水表读数虚高问题研究 被引量:1
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作者 韩义秀 《浙江工贸职业技术学院学报》 2024年第1期70-73,84,共5页
为了定量研究供水网络中总表漏水程度和分表读数虚高程度,根据水量平衡分析法的原理,结合大数据分析技术,建立了一元线性回归方程,回归常数代表总表漏水量程度,回归系数代表分表读数虚高程度。通过针对2021年某高校供水管网的实证研究表... 为了定量研究供水网络中总表漏水程度和分表读数虚高程度,根据水量平衡分析法的原理,结合大数据分析技术,建立了一元线性回归方程,回归常数代表总表漏水量程度,回归系数代表分表读数虚高程度。通过针对2021年某高校供水管网的实证研究表明,总表日均漏水量为15.5958吨,分表读数虚高率为1.07%。该方法对供水管网漏损率的精准评估等问题的解决提供了新的思路和方法。 展开更多
关键词 供水网络 水量平衡分析法 一元线性回归模型 漏水量 虚高
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A Modified Stability Analysis of Two-Dimensional Linear Time Invariant Discrete Systems within the Unity-Shifted Unit Circle
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作者 Periyasamy Ramesh 《Circuits and Systems》 2016年第3期110-118,共9页
This paper proposes a method to ascertain the stability of two dimensional linear time invariant discrete system within the shifted unit circle which is represented by the form of characteristic equation. Further an e... This paper proposes a method to ascertain the stability of two dimensional linear time invariant discrete system within the shifted unit circle which is represented by the form of characteristic equation. Further an equivalent single dimensional characteristic equation is formed from the two dimensional characteristic equation then the stability formulation in the left half of Z-plane, where the roots of characteristic equation f(Z) = 0 should lie within the shifted unit circle. The coefficient of the unit shifted characteristic equation is suitably arranged in the form of matrix and the inner determinants are evaluated using proposed Jury’s concept. The proposed stability technique is simple and direct. It reduces the computational cost. An illustrative example shows the applicability of the proposed scheme. 展开更多
关键词 TWO-dimensionAL Characteristics Equation Unity Shifting Inner Determinant linear Time Invariant Discrete Systems Stability
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一种三维混沌系统的混沌同步研究
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作者 龙丹 陈长宇 《海军工程大学学报》 CAS 北大核心 2024年第3期103-107,共5页
混沌同步在保密通信领域有着广阔的应用前景,但要实现混沌保密通信,位于接收端和发送端的两个混沌系统必须达到混沌同步。为此,采用简单的线性反馈控制实现了一个新三维混沌系统的混沌同步控制,并应用Lyapunov稳定性理论,证明了两个混... 混沌同步在保密通信领域有着广阔的应用前景,但要实现混沌保密通信,位于接收端和发送端的两个混沌系统必须达到混沌同步。为此,采用简单的线性反馈控制实现了一个新三维混沌系统的混沌同步控制,并应用Lyapunov稳定性理论,证明了两个混沌系统在线性反馈控制下实现混沌同步的条件。根据这些同步条件,只要给定系统参数值,就能够判断两个混沌系统是否能够达到混沌同步;另一方面,也可以根据这些判据来选取实现混沌同步的系统参数。最后,进行了计算机仿真,验证了所得到的同步条件是有效的。 展开更多
关键词 混沌系统 混沌同步控制 线性反馈控制
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昆都仑泄洪冲沙洞结构静动力三维有限元配筋计算
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作者 艾喆 王锁 +3 位作者 章莉 张铸 何勇军 李宏恩 《水利水电技术(中英文)》 北大核心 2024年第S01期39-43,共5页
昆都仑水库是一座以防洪、供水为主的综合利用的中型水库。为改善水库泄洪条件,新建泄洪冲沙洞并布置于库区右岸山体内。首先,构建了泄洪冲沙洞三维有限元模型,模拟了各结构的精细构造部位;然后,采用三维线性有限单元法对泄洪冲沙洞开... 昆都仑水库是一座以防洪、供水为主的综合利用的中型水库。为改善水库泄洪条件,新建泄洪冲沙洞并布置于库区右岸山体内。首先,构建了泄洪冲沙洞三维有限元模型,模拟了各结构的精细构造部位;然后,采用三维线性有限单元法对泄洪冲沙洞开展静动力工况下变形、应力分析计算,基于有限元内力法进行内力计算并提出相应配筋方案;最后,进行结构限裂复核验算。选取的配筋计算方案实用可靠,为工程设计提供指导、验证复核作用并成功付诸实施。 展开更多
关键词 泄洪冲沙洞 三维线性有限元 配筋计算 应力图形法
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高维线性回归模型稳健变量选择方法综述
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作者 邹航 姜云卢 《应用概率统计》 CSCD 北大核心 2024年第1期157-181,共25页
随着大数据时代的到来,在经济学、金融学和生物医学等众多研究领域中频繁收集到高维数据.高维数据的特征之一是变量维数p随着样本量n的增加而变大且通常会超过样本量,同时,异常值也容易出现在高维数据中.因此,如何克服异常值给高维统计... 随着大数据时代的到来,在经济学、金融学和生物医学等众多研究领域中频繁收集到高维数据.高维数据的特征之一是变量维数p随着样本量n的增加而变大且通常会超过样本量,同时,异常值也容易出现在高维数据中.因此,如何克服异常值给高维统计推断带来的影响,从而得到更精确的模型,是目前统计学研究的热点问题之一.本文是对高维线性模型下的稳健变量选择方法进行综述.具体地,首先介绍评估稳健性的三个指标:影响函数、崩溃点和最大偏差.其次着重介绍了稳健变量选择方法,包括响应变量含有异常值,响应变量和协变量都含有异常值,高崩溃点且高效的变量选择方法.紧接着介绍相关算法,通过模拟和实例比较不同变量选择方法.最后,简要探讨了高维稳健有效变量选择方法存在的问题及未来的可能发展方向. 展开更多
关键词 高维线性回归模型 稳健性 变量选择 有效性
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改进无模型自适应迭代学习的直线电机滑模控制
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作者 郑鑫鑫 张大海 +1 位作者 曹荣敏 侯忠生 《电机与控制学报》 EI CSCD 北大核心 2024年第7期120-130,共11页
二维直线电机具有非线性、多变量及强耦合等特点,其精确模型无法获得,同时,在实际过程中由于参数摄动及扰动而造成的运行不稳定现象,致使对其跟踪控制十分困难。针对以上问题,根据无模型自适应迭代学习控制不依赖被控系统精确数学模型... 二维直线电机具有非线性、多变量及强耦合等特点,其精确模型无法获得,同时,在实际过程中由于参数摄动及扰动而造成的运行不稳定现象,致使对其跟踪控制十分困难。针对以上问题,根据无模型自适应迭代学习控制不依赖被控系统精确数学模型的特点,及滑模控制具有可设计且与对象参数和扰动无关的滑动模态,提出一种改进无模型自适应迭代学习的滑模结构复合控制策略。在无模型自适应迭代学习控制方案的准则函数中加入误差变化率,并对其收敛性进行分析论证;然后在紧格式动态线性化基础上,设计指数趋近律滑模控制,使改进无模型自适应迭代学习的滑模控制复合策略能够克服不稳定现象并具有很强的鲁棒性,从而进一步提高系统响应速度和控制精度。最后通过仿真和实物验证,控制精度稳定在1μm范围内,并与其他控制方案相比,验证了所提方法的准确性和有效性。 展开更多
关键词 改进无模型自适应迭代学习控制 误差变化率 准则函数 滑模控制 二维直线电机
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零边界条件下一维非线性细胞自动机可逆性的判定算法
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作者 马骏驰 陈伟霖 +2 位作者 王晨 林德福 王超 《计算机科学》 CSCD 北大核心 2024年第10期330-336,共7页
可逆性的性质对于经典的计算机科学理论模型——细胞自动机(Cellular Automata,CA)具有重要意义。尽管CA在零边界条件下的线性规则的可逆性问题已经得到了大量的研究,但非线性规则目前还很少被探索。文中研究了在有限域Z_(p)上一般一维C... 可逆性的性质对于经典的计算机科学理论模型——细胞自动机(Cellular Automata,CA)具有重要意义。尽管CA在零边界条件下的线性规则的可逆性问题已经得到了大量的研究,但非线性规则目前还很少被探索。文中研究了在有限域Z_(p)上一般一维CA的可逆性问题,找到了一种优化Amoroso无限CA满射性判定算法的方法。基于此,文中还提出了在零边界条件下判定一维CA可逆性的算法,其中包括一种在零边界条件下判定一维CA严格可逆性的算法,以及一种基于桶链的在零边界条件下计算一维CA的可逆性函数的算法。这些判定算法不仅适用于线性规则,也适用于非线性规则。除此以外,还证实了可逆性函数总是有一个周期的,且其周期性与对应桶链的周期性有关。文中给出了一些可逆CA的实验结果,并通过实验结果对理论部分进行了补充验证,进一步支持了文章的研究结论。 展开更多
关键词 细胞自动机 非线性规则 可逆性 零边界 一维
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基于角度交会的二维坐标图像测量系统
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作者 程瑶 许文斌 刘云阳 《应用光学》 CAS 北大核心 2024年第2期438-445,共8页
针对基准平面障碍物检测定位问题,设计了一种采用角度交会法测量二维坐标的嵌入式图像检测系统。二维坐标测量系统采用双线法标定线阵CCD图像传感器,并采用角度交会法对被测对象进行坐标计算,从而测得未修正的二维坐标测量结果。采用控... 针对基准平面障碍物检测定位问题,设计了一种采用角度交会法测量二维坐标的嵌入式图像检测系统。二维坐标测量系统采用双线法标定线阵CCD图像传感器,并采用角度交会法对被测对象进行坐标计算,从而测得未修正的二维坐标测量结果。采用控制变量法分别测量X轴和Y轴坐标,使用Matlab软件对数据进行处理,并对X轴和Y轴测量误差分别进行多项式线性拟合,进而得到坐标修正公式,修正的二维坐标误差明显变小。实验结果表明:基于角度交会的二维坐标图像测量系统能够实时、准确、快速和可靠地测量二维坐标,为基准平面障碍物二维坐标测量定位提供了一种可行的方案,具有一定的应用价值和意义。 展开更多
关键词 线阵CCD 二维坐标测量 角度交会法 MATLAB
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基于子空间学习的快速自适应局部比值和判别分析
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作者 曹传杰 王靖 +2 位作者 赵伟豪 周科艺 杨晓君 《计算机应用研究》 CSCD 北大核心 2024年第1期108-115,共8页
降维是处理高维数据的一项关键技术,其中线性判别分析及其变体算法均为有效的监督算法。然而大多数判别分析算法存在以下缺点:a)无法选择更具判别性的特征;b)忽略原始空间中噪声和冗余特征的干扰;c)更新邻接图的计算复杂度高。为了克服... 降维是处理高维数据的一项关键技术,其中线性判别分析及其变体算法均为有效的监督算法。然而大多数判别分析算法存在以下缺点:a)无法选择更具判别性的特征;b)忽略原始空间中噪声和冗余特征的干扰;c)更新邻接图的计算复杂度高。为了克服以上缺点,提出了基于子空间学习的快速自适应局部比值和判别分析算法。首先,提出了统一比值和准则及子空间学习的模型,以在子空间中探索数据的潜在结构,选择出更具判别信息的特征,避免受原始空间中噪声的影响;其次,采用基于锚点的策略构造邻接图来表征数据的局部结构,加速邻接图学习;然后,引入香农熵正则化,以避免平凡解;最后,在多个数据集上进行了对比实验,验证了算法的有效性。 展开更多
关键词 降维 线性判别分析 子空间学习 比值和
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基于Matlab线性规划二次优化在钢筋下料中的应用
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作者 张忠良 《科技资讯》 2024年第18期12-14,47,共4页
以西渝高铁某钢筋加工厂钢筋下料为背景,提出一种通过两次优化过程建立方案组合筛选和方案组合优化的一维线性规划模型,使复杂的优化数学理论问题变得直观易懂。该方法通过算例,利用计算机辅助计算软件Matlab,将上述数学模型应用于施工... 以西渝高铁某钢筋加工厂钢筋下料为背景,提出一种通过两次优化过程建立方案组合筛选和方案组合优化的一维线性规划模型,使复杂的优化数学理论问题变得直观易懂。该方法通过算例,利用计算机辅助计算软件Matlab,将上述数学模型应用于施工现场,提高钢筋下料计算效率和自动化程度,提升了材料的利用率,从而达到节约成本的目的,具有很强的实用性。 展开更多
关键词 一维线性规划 二次优化 MATLAB软件 成本控制
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Review of Dimension Reduction Methods
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作者 Salifu Nanga Ahmed Tijani Bawah +5 位作者 Benjamin Ansah Acquaye Mac-Issaka Billa Francis Delali Baeta Nii Afotey Odai Samuel Kwaku Obeng Ampem Darko Nsiah 《Journal of Data Analysis and Information Processing》 2021年第3期189-231,共43页
<strong>Purpose:</strong><span style="font-family:;" "=""><span style="font-family:Verdana;"> This study sought to review the characteristics, strengths, weak... <strong>Purpose:</strong><span style="font-family:;" "=""><span style="font-family:Verdana;"> This study sought to review the characteristics, strengths, weaknesses variants, applications areas and data types applied on the various </span><span><span style="font-family:Verdana;">Dimension Reduction techniques. </span><b><span style="font-family:Verdana;">Methodology: </span></b><span style="font-family:Verdana;">The most commonly used databases employed to search for the papers were ScienceDirect, Scopus, Google Scholar, IEEE Xplore and Mendeley. An integrative review was used for the study where </span></span></span><span style="font-family:Verdana;">341</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> papers were reviewed. </span><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"> The linear techniques considered were Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), Singular Value Decomposition (SVD), Latent Semantic Analysis (LSA), Locality Preserving Projections (LPP), Independent Component Analysis (ICA) and Project Pursuit (PP). The non-linear techniques which were developed to work with applications that ha</span></span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> complex non-linear structures considered were Kernel Principal Component Analysis (KPC</span><span style="font-family:Verdana;">A), Multi</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">dimensional Scaling (MDS), Isomap, Locally Linear Embedding (LLE), Self-Organizing Map (SOM), Latent Vector Quantization (LVQ), t-Stochastic </span><span style="font-family:Verdana;">neighbor embedding (t-SNE) and Uniform Manifold Approximation and Projection (UMAP). DR techniques can further be categorized into supervised, unsupervised and more recently semi-supervised learning methods. The supervised versions are the LDA and LVQ. All the other techniques are unsupervised. Supervised variants of PCA, LPP, KPCA and MDS have </span><span style="font-family:Verdana;">been developed. Supervised and semi-supervised variants of PP and t-SNE have also been developed and a semi supervised version of the LDA has been developed. </span><b><span style="font-family:Verdana;">Conclusion:</span></b><span style="font-family:Verdana;"> The various application areas, strengths, weaknesses and variants of the DR techniques were explored. The different data types that have been applied on the various DR techniques were also explored.</span></span> 展开更多
关键词 dimension Reduction Machine Learning linear dimension Reduction Techniques Non-linear Reduction Techniques
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铁路工程装配式三维数字化设计方法研究
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作者 薛宇腾 赵非 易菊香 《铁路计算机应用》 2024年第5期26-30,共5页
为解决铁路工程复杂结构形式下设计建模工作量大、建模精度不高、现有三维设计软件适用性弱等问题,建立构件数据存储标准,基于工程装配式思路,将单个构件作为设计单元进行参数化预设计,实现参数与模型的实时交互;将空间几何线抽象为设... 为解决铁路工程复杂结构形式下设计建模工作量大、建模精度不高、现有三维设计软件适用性弱等问题,建立构件数据存储标准,基于工程装配式思路,将单个构件作为设计单元进行参数化预设计,实现参数与模型的实时交互;将空间几何线抽象为设计参数并定义为线状约束,约束构件位置和形态,实现构件的精细化设计和组装;建立构件属性与工程量计算模板的映射关系,将构件参数导入模板,快速计算工程量;采用剖切构件几何轮廓线的方式生成二维图。该研究降低了铁路工程复杂单体构件精细化设计的难度,有效提升了复杂结构物建模和修改的效率。 展开更多
关键词 铁路工程 装配式 三维设计 参数化 线状约束
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超高维数据下部分线性可加分位数回归模型的变量选择
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作者 白永昕 钱曼玲 田茂再 《统计与决策》 CSSCI 北大核心 2024年第9期43-48,共6页
在超高维数据中,一方面,协变量的维数可能远远大于样本量,甚至随着样本量以指数级的速度增长;另一方面,超高维数据通常是异质的,协变量对条件分布中心的影响可能与他们对尾部的影响大不相同,甚至会出现重尾以及异常点的复杂情况。文章... 在超高维数据中,一方面,协变量的维数可能远远大于样本量,甚至随着样本量以指数级的速度增长;另一方面,超高维数据通常是异质的,协变量对条件分布中心的影响可能与他们对尾部的影响大不相同,甚至会出现重尾以及异常点的复杂情况。文章在协变量维度发散且为超高维的情况下研究了部分线性可加分位数回归模型的变量选择和稳健估计问题。首先,为了实现模型的稀疏性和非参数光滑性,引入了一种非凸Atan双惩罚,并采用分位迭代坐标下降算法来解决所提方法的优化问题。在选择适当正则化参数的情况下,证明了所提双惩罚估计量的理论性质。其次,通过模拟研究对所提方法的性能进行验证。模拟结果表明,所提方法比其他惩罚方法具有更好的表现,尤其是在数据存在重尾的情况下。最后,通过基于癌症筛查病人血液样本数据的实证来验证所提方法的实用性。 展开更多
关键词 超高维数据 分位数回归 部分线性可加 变量选择 Atan双惩罚
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