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Simulation of viscoelastic behavior of defected rock by using numerical manifold method

Feng REN, Lifeng FAN, Guowei MA

《结构与土木工程前沿(英文)》 2011年 第5卷 第2期   页码 199-207 doi: 10.1007/s11709-011-0102-1

摘要: Numerical simulations of longitudinal wave propagation in a rock bar with microcracks are conducted by using the numerical manifold method which has great advantages in the simulation of discontinuities. Firstly, validation of the numerical manifold method is carried out by simulations of a longitudinal stress wave propagating through intact and cracked rock bars. The behavior of the stress wave traveling in a one-dimensional rock bar with randomly distributed microcracks is subsequently studied. It is revealed that the highly defected rock bar has significant viscoelasticity to the stress wave propagation. Wave attenuation as well as time delay is affected by the length, quantity, specific stiffness of the distributed microcracks as well as the incident stress wave frequency. The storage and loss moduli of the defected rock are also affected by the microcrack properties; however, they are independent of incident stress wave frequency.

关键词: stress wave propagation     defected rock     numerical manifold method     viscoelastic behavior     storage modulus     loss modulus    

Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

《结构与土木工程前沿(英文)》 2019年 第13卷 第5期   页码 1036-1053 doi: 10.1007/s11709-019-0535-5

摘要: Numerical manifold method (NMM) is an effective method for simulating block system, however, significant errors are found in its simulation of rotation problems. Three kinds of errors, as volume expansion, stress vibration, and attenuation of angular velocity, were observed in the original NMM. The first two kind errors are owing to the small deformation assumption and the last one is due to the numerical damping. A large deformation NMM is proposed based on large deformation theory. In this method, the governing equation is derived using Green strain, the large deformation iteration and the open-close iteration are combined, and an updating strategy is proposed. The proposed method is used to analyze block rotation, beam bending, and rock falling problems and the results prove that all three kinds of errors are eliminated in this method.

关键词: numerical manifold method     rotation     large deformation     Green strain     open-close iteration    

Face recognition based on subset selection via metric learning on manifold

Hong SHAO,Shuang CHEN,Jie-yi ZHAO,Wen-cheng CUI,Tian-shu YU

《信息与电子工程前沿(英文)》 2015年 第16卷 第12期   页码 1046-1058 doi: 10.1631/FITEE.1500085

摘要: With the development of face recognition using sparse representation based classification (SRC), many relevant methods have been proposed and investigated. However, when the dictionary is large and the representation is sparse, only a small proportion of the elements contributes to the 1-minimization. Under this observation, several approaches have been developed to carry out an efficient element selection procedure before SRC. In this paper, we employ a metric learning approach which helps find the active elements correctly by taking into account the interclass/intraclass relationship and manifold structure of face images. After the metric has been learned, a neighborhood graph is constructed in the projected space. A fast marching algorithm is used to rapidly select the subset from the graph, and SRC is implemented for classification. Experimental results show that our method achieves promising performance and significant efficiency enhancement.

关键词: Face recognition     Sparse representation     Manifold structure     Metric learning     Subset selection    

基于Laplacian特征映射的被动毫米波目标识别

罗磊,李跃华,栾英宏

《中国工程科学》 2010年 第12卷 第3期   页码 77-81

摘要:

针对传统被动毫米波金属目标识别方法中特征提取、选择的缺点,采用Laplacian特征映射流形学习算法发现了金属目标回波信号短

关键词: 流形学习     Laplacian特征映射     非线性降维     低维流形     毫米波    

基于流形学习的离群点检测方法

徐雪松,宋东明,张谞,许满武,刘凤玉

《中国工程科学》 2009年 第11卷 第2期   页码 82-87

摘要:

为了提高高维数据集合离群数据挖掘效率,提出了一种基于流形学习的离群点检测算法。局部线性嵌入( locally linear embedding, LLE)算法是流形学习中有效的非线性降维方法,它的优势在于只定义唯一的 参数,即邻域数。根据LLE算法的思想寻找样本数据的内在嵌入分布,并通过邻域数选取和降维后数据点之 间的距离调整,提高了数据集中离群点发现效率,同时利用离群点权值判别式进行权值数据判定,根据权值 的大小标识出数据集中的离群点,仿真实验的结果表明了该方法能够有效地发现高维数据集中的离群点。 与此同时,该算法具有参数估计简单、参数影响不大等优点,该算法为离群点检测问题的机器学习提供了一 条新的途径。

 

关键词: 流形学习     离群点检测     高维数据     维数约减     离群数据    

Iterative HOEO fusion strategy: a promising tool for enhancing bearing fault feature

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0725-z

摘要: As parameter independent yet simple techniques, the energy operator (EO) and its variants have received considerable attention in the field of bearing fault feature detection. However, the performances of these improved EO techniques are subjected to the limited number of EOs, and they cannot reflect the non-linearity of the machinery dynamic systems and affect the noise reduction. As a result, the fault-related transients strengthened by these improved EO techniques are still subject to contamination of strong noises. To address these issues, this paper presents a novel EO fusion strategy for enhancing the bearing fault feature nonlinearly and effectively. Specifically, the proposed strategy is conducted through the following three steps. First, a multi-dimensional information matrix (MDIM) is constructed by performing the higher order energy operator (HOEO) on the analysis signal iteratively. MDIM is regarded as the fusion source of the proposed strategy with the properties of improving the signal-to-interference ratio and suppressing the noise in the low-frequency region. Second, an enhanced manifold learning algorithm is performed on the normalized MDIM to extract the intrinsic manifolds correlated with the fault-related impulses. Third, the intrinsic manifolds are weighted to recover the fault-related transients. Simulation studies and experimental verifications confirm that the proposed strategy is more effective for enhancing the bearing fault feature than the existing methods, including HOEOs, the weighting HOEO fusion, the fast Kurtogram, and the empirical mode decomposition.

关键词: higher order energy operator     fault diagnosis     manifold learning     rolling element bearing     information fusion    

利用流形学习进行基于图像的三维模型检索 None

Pan-pan MU, San-yuan ZHANG, Yin ZHANG, Xiu-zi YE, Xiang PAN

《信息与电子工程前沿(英文)》 2018年 第19卷 第11期   页码 1397-1408 doi: 10.1631/FITEE.1601764

摘要: 提出一种基于图像的三维模型检索新框架。把查询的图像建模为欧氏空间的一个点,把三维模型所有投影视图建模为一个对称正定矩阵,并视该对称正定矩阵为黎曼流形上的一个点。于是,基于图像的三维模型检索简化为欧氏空间到黎曼流形上的度量学习。为解决异质匹配问题,把欧式空间和对称正定矩阵黎曼空间映射到同一个高维希尔伯特空间,极大缩小彼此之间语义鸿沟。最后,使用核方法设计一个优化算法学习映射。任何新图像描述符,比如深度学习特征描述符,可以很容易嵌入该框架。实验结果表明,该方法相较目前最新基于图像的三维模型检索方法有一定优势。

关键词: 模型检索;欧式空间;黎曼流形;希尔伯特空间;度量学习    

基于微分流形理论和分岔理论的飞机安全性分析 None

Chi ZHOU, Ying-hui LI, Wu-ji ZHENG, Peng-wei WU

《信息与电子工程前沿(英文)》 2019年 第20卷 第2期   页码 292-299 doi: 10.1631/FITEE.1700435

摘要: 失控(LOC)被认为是导致世界范围内致命飞机事故的主要原因之一。减少飞机失控对于提高飞行安全意义重大。虽然目前航空界对失控的定义还比较模糊,但研究表明失控通常与飞行状态超出安全包线、飞机动力学的非线性影响以及飞行机组人员不当操纵有关。本文主要针对飞机动力学的非线性影响和驾驶员不当操纵导致的失控展开研究,利用分岔分析方法确定飞行状态的失速点和分岔点。研究结果表明,驾驶员操纵过度将直接导致飞机失速。此外,飞行状态接近飞行包线边界时,驾驶员的操纵会变得特别敏感,稍微改变操纵指令就可能导致飞行状态超出安全包线。即使在某个操纵指令下存在稳定平衡状态,飞行状态仍可能处于安全包线之外。为提升飞行安全,引入微分流形理论确定安全包线。以NASA的通用模型作为案例展开研究。

关键词: 失控;安全包线;飞机动力学;分岔分析;微分流形理论    

地下工程新技术的实践

马洪琪

《中国工程科学》 2002年 第4卷 第11期   页码 37-41

摘要:

广蓄电站高压岔管的P. D值达5.8×10kN·m,未采用常规的钢岔管,在钢筋混凝土岔管设计原则上,主要依靠围岩承担水压力。施工中从控制爆破、混凝土质量、高压灌浆等方面实现设计意图。这种结构安全可靠,投资省,效益好。广蓄斜井引进了一套间断式的斜井滑模,经改进和完善,获得了成功。在天荒坪抽水蓄能电站长斜井施工中,研制了自主知识产权的XHM-7型斜井滑模设备,实现了斜井混凝土衬砌的连续滑升,显示了该设备结构新颖、安全可靠、速度快、造价低的优势。以上两项新技术的成功实践,为我国类似工程的推广和应用提供了有益的经验。

关键词: 水电     地下工程     岔管     斜井     新技术    

Study on emissions reduction of DMCC engine with oxidation catalyst

YAO Chunde, LIU Xibo, WANG Hongfu, LIU Xiaoping, CHENG Chuanhui, WANG Yinshan

《能源前沿(英文)》 2007年 第1卷 第4期   页码 441-445 doi: 10.1007/s11708-007-0064-4

摘要: A new combustion model diesel/methanol compound combustion (DMCC) is presented, in which methanol is injected into manifold and ignited by certain amount of diesel fuel. The results showed that DMCC remarkably decreased the emission

关键词: combustion     manifold     DMCC     emission     diesel/methanol compound    

网络系统行为效用计算——概念与原理 Article

胡昌振

《工程(英文)》 2018年 第4卷 第1期   页码 78-84 doi: 10.1016/j.eng.2018.02.010

摘要:
网络的服务与应用是一个面向业务与任务的行为过程,其度量与评估目前尚处于粗略比较状态。本文把网络行为场景刻画为微分流形,根据光滑微分流形的同胚变换,给出了网络行为的数学定义,提出了网络行为路径及行为效用的数学描述。基于微分几何原理,提出了网络行为效用的计算原理与方法,并构建了基于行为效用的网络攻防对抗评估计算框架,从而奠定了网络行为定量度量和评估的数学基础。

关键词: 网络度量评估     微分流形     网络行为效用     网络攻防对抗    

小型制冷系统的稳态模拟

王婷,陈海耿,赵巍,崔苗

《中国工程科学》 2007年 第9卷 第3期   页码 97-102

摘要:

所建立的小型制冷系统模型包括压缩机、冷凝器、膨胀阀和蒸发器四个部件模型以及使系统封闭的 充灌量模型,实现了所有相关物性参数计算的程序化以便于模型的数值求解。在蒸发器模型中提出了析湿系数 的新算法,加速了模型的计算。用所建立的模型模拟工作参数的变化对系统性能的影响,其结果与实际规律相 符合,证明了该模型的正确性。根据模型得出的定量结果可分析各性能参数变化的相互影响,并对性能参数的 敏感性进行分析,为系统优化和控制提供理论依据。此外,换热器模型还可独立用于各种换热器性能的分析与优化。

关键词: 制冷系统     析湿系数     稳态模型    

A novel classification method for aid decision of traditional Chinese patent medicines for stroke treatment

null

《医学前沿(英文)》 2017年 第11卷 第3期   页码 432-439 doi: 10.1007/s11684-017-0511-1

摘要:

Traditional Chinese patent medicines are widely used to treat stroke because it has good efficacy in the clinical environment. However, because of the lack of knowledge on traditional Chinese patent medicines, many Western physicians, who are accountable for the majority of clinical prescriptions for such medicine, are confused with the use of traditional Chinese patent medicines. Therefore, the aid-decision method is critical and necessary to help Western physicians rationally use traditional Chinese patent medicines. In this paper, Manifold Ranking is employed to develop the aid-decision model of traditional Chinese patent medicines for stroke treatment. First, 115 stroke patients from three hospitals are recruited in the cross-sectional survey. Simultaneously, traditional Chinese physicians determine the traditional Chinese patent medicines appropriate for each patient. Second, particular indicators are explored to characterize the population feature of traditional Chinese patent medicines for stroke treatment. Moreover, these particular indicators can be easily obtained by Western physicians and are feasible for widespread clinical application in the future. Third, the aid-decision model of traditional Chinese patent medicines for stroke treatment is constructed based on Manifold Ranking. Experimental results reveal that traditional Chinese patent medicines can be differentiated. Moreover, the proposed model can obtain high accuracy of aid decision.

关键词: traditional Chinese patent medicines     stroke     aid decision     data mining     manifold ranking    

岩石冲击损伤演化规律数值流形方法模拟

刘红岩,吕淑然,秦四清

《中国工程科学》 2007年 第9卷 第3期   页码 92-96

摘要:

采用应力波衰减损伤模型对仅适用于模拟基于线性本构关系和恒定载荷作用下物体变形规律的数值 流形程序进行了扩展;利用扩展后的程序对岩石长杆在冲击载荷作用下的损伤演化规律进行了模拟,得出了不 同位置点处的损伤演化曲线和材料总体的损伤演化曲线。模拟结果表明,损伤的增加主要集中在冲击载荷作用的初始阶段,随着时间的推移,应力波强度衰减,损伤将不再明显增加。

关键词: 岩石     数值流形方法     冲击损伤     演化规律    

Hierarchical fractal structure of perfect single-layer graphene

T. Zhang, K. Ding

《机械工程前沿(英文)》 2013年 第8卷 第4期   页码 371-382 doi: 10.1007/s11465-013-0279-1

摘要:

The atomic lattice structure of perfect single-layer graphene that can actually be regarded as a kind of hierarchical fractal structure from the perspective of fractal geometry was studied for the first time. Three novel and special discoveries on hierarchical fractal structure and sets were unveiled upon examination of the regular crystal lattices of the single-layer graphene. The interior fractal-type structure was discovered to be the fifth space-filling curve from physical realm. Two efficient methods for calculating the fractal dimension of this fresh member was also provided. The outer boundary curve had a fractal dimension equal to one, and a multi-fractal structure from a naturally existing material was found for the first time. A series of strict self-similar hexagons comprised a rotating fractal set. These hexagons slewed at a constant counterclockwise angle of 19.1° when observed from one level to the next higher level. From the perspective of fractal geometry, these pioneering discoveries added three new members to the existing regular fractal structures and sets. A fundamental example of a multi-fractal structure was also presented.

关键词: hierarchical fractal structure     fractal dimension     the fifth space-filling curve     multi-fractal structure    

标题 作者 时间 类型 操作

Simulation of viscoelastic behavior of defected rock by using numerical manifold method

Feng REN, Lifeng FAN, Guowei MA

期刊论文

Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

期刊论文

Face recognition based on subset selection via metric learning on manifold

Hong SHAO,Shuang CHEN,Jie-yi ZHAO,Wen-cheng CUI,Tian-shu YU

期刊论文

基于Laplacian特征映射的被动毫米波目标识别

罗磊,李跃华,栾英宏

期刊论文

基于流形学习的离群点检测方法

徐雪松,宋东明,张谞,许满武,刘凤玉

期刊论文

Iterative HOEO fusion strategy: a promising tool for enhancing bearing fault feature

期刊论文

利用流形学习进行基于图像的三维模型检索

Pan-pan MU, San-yuan ZHANG, Yin ZHANG, Xiu-zi YE, Xiang PAN

期刊论文

基于微分流形理论和分岔理论的飞机安全性分析

Chi ZHOU, Ying-hui LI, Wu-ji ZHENG, Peng-wei WU

期刊论文

地下工程新技术的实践

马洪琪

期刊论文

Study on emissions reduction of DMCC engine with oxidation catalyst

YAO Chunde, LIU Xibo, WANG Hongfu, LIU Xiaoping, CHENG Chuanhui, WANG Yinshan

期刊论文

网络系统行为效用计算——概念与原理

胡昌振

期刊论文

小型制冷系统的稳态模拟

王婷,陈海耿,赵巍,崔苗

期刊论文

A novel classification method for aid decision of traditional Chinese patent medicines for stroke treatment

null

期刊论文

岩石冲击损伤演化规律数值流形方法模拟

刘红岩,吕淑然,秦四清

期刊论文

Hierarchical fractal structure of perfect single-layer graphene

T. Zhang, K. Ding

期刊论文