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A new fracture criterion for peridynamic and dual-horizon peridynamics

Jinhai ZHAO, Hesheng TANG, Songtao XUE

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 629-641 doi: 10.1007/s11709-017-0447-1

摘要： A new fracture criterion based on the crack opening displacement for peridynamic (PD) and dual-horizon peridynamics (DH-PD) is proposed. When the relative deformation of the PD bond between the particles reaches the critical crack tip opening displacement of the fracture mechanics, we assume that the bond force vanishes. A new damage rule similar to the local damage rule in conventional PD is introduced to simulate fracture. The new formulation is developed for a linear elastic solid though the extension to nonlinear materials is straightforward. The performance of the new fracture criterion is demonstrated by four examples, i.e. a bilateral crack problem, double parallel crack, monoclinic crack and the double inclined crack. The results are compared to experimental data and the results obtained by other computational methods.

关键词： Castigliano’s theorem     breaking energy     critical extension     XFEM     COD     PD-COD    

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水机材料的抗磨蚀性判据研究

王飚,王宇栋,张自华,叶献国

《中国工程科学》 2003年 第5卷 第7期   页码 58-61

摘要：

为了证实水机材料的抗磨蚀和抗空蚀性能与材料的常规宏观性能之间的相依关系，选取4种具代表性的材料（碳化钨涂层、NiCr合金涂层、硼不锈钢涂层和钛），进行空蚀和磨蚀试验，并测试了它们的硬度和抗腐蚀性。试验结果表明，材料的空蚀和磨蚀抗力与硬度和抗腐蚀性有着紧密的相依关系：高硬度是抗磨蚀性优的第一判据，较强的抗腐蚀性是第二判据；高抗腐蚀性是抗空蚀性优的第一判据，较高的硬度是第二判据。

关键词： 水机材料     磨蚀     判据    

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Classical state feedback controller for nonlinear systems using mean value theorem: closed loop-FOC of

Abrar ALLAG,Abdelhamid BENAKCHA,Meriem ALLAG,Ismail ZEIN,Mohamed Yacine AYAD

《能源前沿（英文）》 2015年 第9卷 第4期   页码 413-425 doi: 10.1007/s11708-015-0379-1

摘要： The problem of state feedback controllers for a class of Takagi-Sugeno (T-S) Lipschitz nonlinear systems is investigated. A simple systematic and useful synthesis method is proposed based on the use of the differential mean value theorem (DMVT) and convex theory. The proposed design approach is based on the mean value theorem (MVT) to express the nonlinear error dynamics as a convex combination of known matrices with time varying coefficients as linear parameter varying (LPV) systems. Using the Lyapunov theory, stability conditions are obtained and expressed in terms of linear matrix inequalities (LMIs). The controller gains are then obtained by solving linear matrix inequalities. The effectiveness of the proposed approach for closed loop-field oriented control (CL-FOC) of permanent magnet synchronous machine (PMSM) drives is demonstrated through an illustrative simulation for the proof of these approaches. Furthermore, an extension for controller design with parameter uncertainties and perturbation performance is discussed.

关键词： Takagi-Sugeno (T-S) fuzzy systems     sector nonlinearity     nonlinear controller     linear matrix inequality (LMI) approach     differential mean value theorem (DMVT)     field oriented control (FOC)     linear parameter varying (LPV)    

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双枝模糊决策与决策识别问题

史开泉,李歧强

《中国工程科学》 2001年 第3卷 第1期   页码 71-77

摘要：

文章提出具有中性域X*(X*≠{x})X的上的双枝模糊决策的概念和决策优化分析模型、决策判定定理、决策识别定理、决策去余定理和决策因素域X上的挖洞原理。双枝模糊决策具有下列特征：决策结论的双向依赖特性，决策结论的叠加合成特性，决策结论的枝-分离特性，决策结论的枝-退化特性，决策结论的非失误特性。研究结果得到了应用。

关键词： 双枝模糊决策     决策模型     决策判定定理     决策识别定理     决策去余定理     挖洞原理    

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Application of consistent geometric decomposition theorem to dynamic finite element of 3D composite beam

Iman FATTAHI, Hamid Reza MIRDAMADI, Hamid ABDOLLAHI

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 675-689 doi: 10.1007/s11709-020-0625-4

摘要： Analyzing static and dynamic problems including composite structures has been of high significance in research efforts and industrial applications. In this article, equivalent single layer approach is utilized for dynamic finite element procedures of 3D composite beam as the building block of numerous composite structures. In this model, both displacement and strain fields are decomposed into cross-sectional and longitudinal components, called consistent geometric decomposition theorem. Then, the model is discretized using finite element procedures. Two local coordinate systems and a global one are defined to decouple mechanical degrees of freedom. Furthermore, from the viewpoint of consistent geometric decomposition theorem, the transformation and element mass matrices for those systems are introduced here for the first time. The same decomposition idea can be used for developing element stiffness matrix. Finally, comprehensive validations are conducted for the theory against experimental and numerical results in two case studies and for various conditions.

关键词： composite beam     dynamic finite element     degrees of freedom coupling     experimental validation     numerical validation    

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生成锁P<G,X,X'>和它的中央加密系统

史开泉,陈泽雄

《中国工程科学》 2000年 第2卷 第2期   页码 41-46

摘要：

利用数据生成技术，提出生成锁P <G ,X, X´>的概念和由P <G ,X, X´>构成的中央加密系统。这些系统是：生成锁P <G ,X, X´>与单齿中央加密系统，生成锁P <G ,X, X´>与多齿中央加密系统。给出单齿加密-解密算法，多齿加密-解密算法，多齿静态加密-解密算法，多齿动态加密-解密算法，中央加密系统的结构特性。研究指出：任意两个秘密通讯的双方A和B，它们各自选择无规则分布的正整数集合XA={x1，x2，…，xn}，XB={x1，x2，…，xm}，m,n≥4，XA≠XB，利用P <G ,X, X´>完成双方之间的秘密通讯。研究结果表明，所提出的方法具有良好的应用性，安全性。

关键词： 生成锁     中央加密系统     多齿加密-解密算法     P    X     X'>存在定理     数位签章唯一性定理    

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A survey of instantaneous poles for a class of two-degree-of-freedom spherical mechanisms

Soheil ZARKANDI

《机械工程前沿（英文）》 2014年 第9卷 第4期   页码 344-353 doi: 10.1007/s11465-014-0320-z

摘要：

This paper is a detailed exploration of instantaneous poles for a class of two-degree-of-freedom (two-DOF) spherical mechanisms (SMs) with seven links or bars. For two-DOF SMs, the secondary instantaneous poles (the ones which cannot be found by direct inspection) must lie on the specified great circles. For many of these mechanisms, however, some of these great circles cannot be obtained by a direct application of Aronhold-Kennedy theorem. This paper presents geometrical and analytical techniques to locate these unknown great circles for three topologies of seven-bar two-DOF SMs.

关键词： spherical mechanisms     instantaneous poles     Aronhold-Kennedy theorem     great circles     pencil of meridian    

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Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1480-1493 doi: 10.1007/s11709-021-0776-y

摘要： In waterfront geotechnical engineering, seismic and drainage conditions must be considered in the design of retaining structures. This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions. The method comprises the following steps: i) determination of the total head, ii) upper bound solution of seismic active earth thrust, and iii) deduction for the earth pressure distribution. The determination of total head h(x,z) relies on the Fourier series expansions, and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem. Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure. The numerical results confirm the validity of the total head distribution. Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure. The method can be applied to the seismic design of waterfront retaining walls.

关键词： seismic active earth pressure     partial seepage flow     pore pressure     anisotropy     upper bound theorem    

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基于对称多项式辅助的中国余数定理的脉冲多普勒雷达多目标距离估计算法 Research Articles

曹成虎1,赵永波1,2

《信息与电子工程前沿（英文）》 2022年 第23卷 第2期   页码 304-316 doi: 10.1631/FITEE.2000418

摘要： 工作在高脉冲重复频率的脉冲多普勒雷达能避免多普勒模糊，但是高脉冲重复频率在许多场合导致距离模糊。目前，解决距离模糊的有效方案是基于波形设计，但是增加了雷达系统的复杂性。由于目标距离和量测距离的对应关系未知，传统的基于多脉冲重复频率方案，特别是中国余数定理，很难应用于多目标距离解模糊。本文旨在研究量测距离含有误差的基于中国余数定理多目标距离估计方法。提出基于对称多项式辅助的中国余数定理，能有效从含有误差的量测距离中重建多目标距离。封闭式鲁棒中国余数定理和基于Aitken加速算法的多项式方程求解方法能有效降低所提算法的计算复杂度。

关键词： 距离模糊；误差距离；多目标；对称多项式辅助的中国余数定理    

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Observer design for induction motor: an approach based on the mean value theorem

Mohamed Yacine HAMMOUDI,Abdelkarim ALLAG,Mohamed BECHERIF,Mohamed BENBOUZID,Hamza ALLOUI

《能源前沿（英文）》 2014年 第8卷 第4期   页码 426-433 doi: 10.1007/s11708-014-0314-x

摘要： In this paper, observer design for an induction motor has been investigated. The peculiarity of this paper is the synthesis of a mono-Luenberger observer for highly coupled system. To transform the nonlinear error dynamics for the induction motor into the linear parametric varying (LPV) system, the differential mean value theorem combined with the sector nonlinearity transformation has been used. Stability conditions based on the Lyapunov function lead to solvability of a set of linear matrix inequalities. The proposed observer guarantees the global exponential convergence to zero of the estimation error. Finally, the simulation results are given to show the performance of the observer design.

关键词： observer design     differential mean value theorem (DMVT)     sector nonlinearity transformation     linear matrix inequalities (LMI)     induction motor    

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Probabilistic stability of uncertain composite plates and stochastic irregularity in their buckling mode shapes: A semi-analytical non-intrusive approach

《结构与土木工程前沿（英文）》   页码 179-190 doi: 10.1007/s11709-022-0888-z

摘要： In this study, the mechanical properties of the composite plate were considered Gaussian random fields and their effects on the buckling load and corresponding mode shapes were studied by developing a semi-analytical non-intrusive approach. The random fields were decomposed by the Karhunen−Loève method. The strains were defined based on the assumptions of the first-order and higher-order shear-deformation theories. Stochastic equations of motion were extracted using Euler–Lagrange equations. The probabilistic response space was obtained by employing the non-intrusive polynomial chaos method. Finally, the effect of spatially varying stochastic properties on the critical load of the plate and the irregularity of buckling mode shapes and their sequences were studied for the first time. Our findings showed that different shear deformation plate theories could significantly influence the reliability of thicker plates under compressive loading. It is suggested that a linear relationship exists between the mechanical properties’ variation coefficient and critical loads’ variation coefficient. Also, in modeling the plate properties as random fields, a significant stochastic irregularity is obtained in buckling mode shapes, which is crucial in practical applications.

关键词： uncertain composite plate     stochastic assume mode method     Karhunen−Loève theorem     polynomial chaos approach     plate buckling     irregularity in buckling mode shapes    

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’s Best Papers of 2015

《环境科学与工程前沿（英文）》 2016年 第10卷 第4期 doi: 10.1007/s11783-016-0858-6

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Anion-exchange membrane direct ethanol fuel cells: Status and perspective

T.S. Zhao, Y.S. Li, S.Y. Shen

《能源前沿（英文）》 2010年 第4卷 第4期   页码 443-458 doi: 10.1007/s11708-010-0127-5

摘要： Direct ethanol fuel cells (DEFCs) are a promising carbon-neutral and sustainable power source for portable, mobile, and stationary applications. However, conventional DEFCs that use acid proton-exchange membranes (typically Nafion type) and platinum-based catalysts exhibit low performance (i.e., the state-of-the-art peak power density is 79.5 mW/cm at 90°C). Anion-exchange membrane (AEM) DEFCs that use low-cost AEM and non-platinum catalysts have recently been demonstrated to yield a much better performance (i.e., the state-of-the-art peak power density is 160 mW/cm at 80°C). This paper provides a comprehensive review of past research on the development of AEM DEFCs, including the aspects of catalysts, AEMs, and single-cell design and performance. Current and future research challenges are identified along with potential strategies to overcome them.

关键词： fuel cell     direct ethanol fuel cells     anion-exchange membrane     ethanol oxidation reaction     oxygen reduction reaction     cell performance    

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任意金属—介电混合体面体面电场积分方程（SVS-EFIE）的增强解 Research Article

王涵,庞铭杰,林海

《信息与电子工程前沿（英文）》 2022年 第23卷 第7期   页码 1098-1109 doi: 10.1631/FITEE.2100387

摘要： 利用矩量法求解面体面电场积分方程（SVS-EFIE），公式复杂，实现困难，算法复杂度高。本文提出求解任意金属—介电混合体电磁散射问题的通用矩阵方程（GME），并给出该方程的增强解。矩量法只考虑包含3个区域的金属—介电混合体，且SVS-EFIE的两步过程导致两个积分符号，难以实现且算法复杂度高。为解决该问题，本文首次提出能够用于分析均匀介质体和超过3个区域金属—介电混合体的GME方法。提出基于耦合度和子区域间距相关的GME加速求解策略，并自适应设置耦合度标准以平衡精度和效率。将变形后的加法定理用于强耦合情况，将迭代法用于弱耦合情况。并行性可以方便地应用于该增强解。数值结果表明，与直接解相比，该方法平均只需11.6%的内存和11.8%的中央处理器时间。

关键词： 混合体；积分方程；矩量法；加法定理；迭代    

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Astrocytes in depression and Alzheimer’s disease

《医学前沿（英文）》 2021年 第15卷 第6期   页码 829-841 doi: 10.1007/s11684-021-0875-0

摘要： Astrocytes are an abundant subgroup of cells in the central nervous system (CNS) that play a critical role in controlling neuronal circuits involved in emotion, learning, and memory. In clinical cases, multiple chronic brain diseases may cause psychosocial and cognitive impairment, such as depression and Alzheimer’s disease (AD). For years, complex pathological conditions driven by depression and AD have been widely perceived to contribute to a high risk of disability, resulting in gradual loss of self-care ability, lower life qualities, and vast burden on human society. Interestingly, correlational research on depression and AD has shown that depression might be a prodrome of progressive degenerative neurological disease. As a kind of multifunctional glial cell in the CNS, astrocytes maintain physiological function via supporting neuronal cells, modulating pathologic niche, and regulating energy metabolism. Mounting evidence has shown that astrocytic dysfunction is involved in the progression of depression and AD. We herein review the current findings on the roles and mechanisms of astrocytes in the development of depression and AD, with an implication of potential therapeutic avenue for these diseases by targeting astrocytes.

关键词： astrocytes     depression     Alzheimer’s disease     roles     mechanisms    

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标题 作者 时间 类型 操作

A new fracture criterion for peridynamic and dual-horizon peridynamics

Jinhai ZHAO, Hesheng TANG, Songtao XUE

期刊论文

水机材料的抗磨蚀性判据研究

王飚,王宇栋,张自华,叶献国

期刊论文

Classical state feedback controller for nonlinear systems using mean value theorem: closed loop-FOC of

Abrar ALLAG,Abdelhamid BENAKCHA,Meriem ALLAG,Ismail ZEIN,Mohamed Yacine AYAD

期刊论文

双枝模糊决策与决策识别问题

史开泉,李歧强

期刊论文

Application of consistent geometric decomposition theorem to dynamic finite element of 3D composite beam

Iman FATTAHI, Hamid Reza MIRDAMADI, Hamid ABDOLLAHI

期刊论文

生成锁P<G,X,X'>和它的中央加密系统

史开泉,陈泽雄

期刊论文

A survey of instantaneous poles for a class of two-degree-of-freedom spherical mechanisms

Soheil ZARKANDI

期刊论文

Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

期刊论文

基于对称多项式辅助的中国余数定理的脉冲多普勒雷达多目标距离估计算法

曹成虎1,赵永波1,2

期刊论文

Observer design for induction motor: an approach based on the mean value theorem

Mohamed Yacine HAMMOUDI,Abdelkarim ALLAG,Mohamed BECHERIF,Mohamed BENBOUZID,Hamza ALLOUI

期刊论文

Probabilistic stability of uncertain composite plates and stochastic irregularity in their buckling mode shapes: A semi-analytical non-intrusive approach

期刊论文

’s Best Papers of 2015

期刊论文

Anion-exchange membrane direct ethanol fuel cells: Status and perspective

T.S. Zhao, Y.S. Li, S.Y. Shen

期刊论文

任意金属—介电混合体面体面电场积分方程（SVS-EFIE）的增强解

王涵,庞铭杰,林海

期刊论文

Astrocytes in depression and Alzheimer’s disease

期刊论文