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Acta Mechanica Solida Sinica 2017年第3期30卷 318-326页

作者： Aizhong Lu Ning Zhang Guisen zeng Institute of Hydroelectric and Oeotechnical Engineering North China Electric Power University102206BeijingChina

When concentrated forces are applied at any points of the outer region of an ellipse in an infinite plate, the complex potentials are determined using the conformal mapping method and Cauchy＇s integral formula. And then, based on the superposition principle, the analyt- ical solutions for stress around an elliptical hole in an infinite plate subjected to a uniform far-field stress and concentrated forces, are obtained. Tangential stress concentration will occur on the hole boundary when only far-field uniform loads are applied. When concen- trated forces are applied in the reversed directions of the uniform loads, tangential stress concentration on the hole boundary can be released significantly. In order to minimize the tangential stress concentration, we need to determine the optimum positions and values of the concentrated forces. Three different optimization methods are applied to achieve this aim. The results show that the tangential stress can be released significantly when the op- timized concentrated forces are applied.

关键词： Elliptical hole Closed-form solution for stress Cauchy's integral method Minimum stress concentration Optimization

Current status of radiology in China

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World journal of Gastroenterology 2000年第2期6卷 193-197页

作者： zeng SM Zhou KR Zhang Zy Peng Wj yang FH Lin j yang j Han Xy Shanghai Med Univ Zhongshan Hosp Dept Radiol Shanghai 200032 Peoples R China

INTRODUCTIONRadiology has been greatly advanced in China sinceits founding in 1949 and has been developed fasterand further more since China adopted the policy ofsocioeconomic reform in *** plays anincreasingly important role in the medical healthcare and treatment in the country and has reachedthe world’s advanced level in certain *** nowbriefly review the history of China’s radiology so asto give a clear picture of its development.

关键词： radiology/history radiology/leducation radiology/trends China

Aeroservoelastic modeling and analysis of a canard-configured air-breathing hypersonic vehicles

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Chinese journal of Aeronautics 2013年第4期26卷 831-840页

作者： zeng Kaichun Xiang jinwu Li Daochun School of Aeronautic Science and Engineering Beihang University

Air-breathing hypersonic vehicles （HSVs） are typically characterized by interactions of elasticity, propulsion and rigid-body flight dynamics, which may result in intractable aeroservoelastic problem. When canard is added, this problem would be even intensified by the introduction of low-frequency canard pivot mode. This paper concerns how the aeroservoelastic stability of a canard-configured HSV is affected by the pivot stiffnesses of all-moveable horizontal tail （HT） and canard. A wing/pivot system model is developed by considering the pivot torsional flexibility, fuselage vibration, and control input. The governing equations of the aeroservoelastic system are established by combining the equations of rigid-body motion, elastic fuselage model, wing/pivot system models and actuator dynamics. An unsteady aerodynamic model is developed by steady Shock-Expansion theory with an unsteady correction using local piston theory. A baseline controller is given to provide approximate inflight characteristics of rigid-body modes. The vehicle is trimmed for equilibrium state, around which the linearized equations are derived for stability analysis. A comparative study of damping ratios, closed-loop poles and responses are conducted with varying controller gains and pivot stiffnesses. Available bandwidth for control design is discussed and feasible region for pivot stiffnesses of HT and canard is given.

关键词： Aeroservoelasticity Canard Flight dynamics Hypersonic vehicles Pivot Stability

A joint mid-course and terminal course cooperative guidance law for multi-missile salvo attack

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Chinese journal of Aeronautics 2018年第6期31卷 1311-1326页

作者： jie zeng Lihua DOU Bin XIN School of Automation Beijing Institute of Technology Beijing 100081 China State Key Laboratory of Intelligent Control and Decision of-Complex Systems Beijing 100081 China

Salvo attacking a surface target by multiple missiles is an effective tactic to enhance the lethality and penetrate the defense system. However, existing cooperative guidance laws in the midcourse or terminal course are not suitable for long-and medium-range missiles or stand-off attacking. Because the initial conditions of cooperative terminal guidance that are generally generated from the mid-course flight may not lead to a successful cooperative terminal guidance without proper mid-course flight adjustment. Meanwhile, cooperative guidance in the mid-course cannot solely guarantee the accuracy of a simultaneous arrival of multiple missiles. Therefore, a joint mid-course and terminal course cooperative guidance law is developed. By building a distinct leader-follower framework, this paper proposes an efficient coordinated Dubins path planning method to synchronize the arrival time of all engaged missiles in the mid-course flight. The planned flight can generate proper initial conditions for cooperative terminal guidance, and also benefit an earliest simultaneous arrival. In the terminal course, an existing cooperative proportional navigation guidance law guides all the engaged missiles to arrive at a target accurately and *** integrated guidance law for an intuitive application is summarized. Simulations demonstrate that the proposed method can generate fast and accurate salvo attack.

关键词： Cooperative systems Dubins path Mid-course flight Missile guidance Salvo attack

Dynamic shared segment protection algorithm with differentiated reliability in GMPLS networks

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journal of Systems Engineering and Electronics 2009年第1期20卷 178-184页

作者： Wang yan Zheng junhu zeng jiazhi Coll. of Computer Science and Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P. R. China Coll. of Computer Science and Technology Southwest Univ. for Nationalities Chengdu 610041 P. R. China.

To improve the resource utilization ratio and shorten the recovery time of the shared path protection with differentiated reliability （SPP-DiR） algorithm, an algorithm called dynamic shared segment protection with differentiated reliability （DSSP-DiR） is proposed for survivable GMPLS networks. In the proposed algorithm, a primary path is dynamically divided into several segments according to the differentiated reliability requirements of the customers. In the SPP-DiR algorithm, the whole primary path should be protected, while in the DSSP- DiR algorithm, only partial segments on the primary path need to be protected, which can reduce more backup bandwidths than that in the SPP-DiR algorithm. Simulation results show that the DSSP-DiR algorithm achieves higher resource utilization ratio, lower protection failure probability, and shorter recovery time than the SPP-DiR algorithm.

关键词： generalized multiprotocal label switching segment protection differentiated reliability resource uti-lization ratio.

New carbazole-substituted siloles for the fabrication of efficient non-doped OLEDs

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Chinese Chemical Letters 2019年第3期30卷 592-596页

作者： yi Xiong jiajie zeng Bin Chen jacky W.y.Lam Zujin Zhao Shuming Chen Ben Zhong Tang State Key Laboratory of Luminescent Materials and Devices Center for Aggregation-Induced Emission South China University of Technology Department of Chemistry Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction The Hong Kong University of Science & Technology Department of Electrical and Electronic Engineering South University of Science and Technology of China

Luminogenic molecules with aggregation-induced emission(AIE) property are free of aggregationcaused quenching and thus have great potential in the fabrication of efficient non-doped OLEDs. Herein, a series of new carbazole-substituted siloles have been synthesized and characterized. Their crystal and electronic structures, thermal stabilities, electrochemical behaviors, and photophysical properties are thoroughly investigated. These silole derivatives exhibit prominent AIE characteristics with high emission efficiencies in solid films. They can function as light-emitting layers in non-doped OLEDs,affording eminent electroluminescence efficiencies of 17.59 cd/A, 12.55 Im/W and 5.63%, amongst the most efficient non-doped OLEDs based on fluorescent emitters, indicating their promising applications in OLEDs.

关键词： Aggregation-induced emission Silole Photoluminescence Electroluminescence Organic light-emitting diode

Prediction model of interval grey number based on DGM(1,1)

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journal of Systems Engineering and Electronics 2010年第4期21卷 598-603页

作者： Bo zeng Sifeng Liu Naiming Xie College of Business Planning Chongqing Technology and Business University Chongqing 400067 E R. China College of Economics and Management Nanjing University of Aeronautics and Astronautics Nanjing 210016 P. R. China

In grey system theory,the studies in the field of grey prediction model are focused on real number sequences,rather than grey number ***,a prediction model based on interval grey number sequences is *** mining the geometric features of interval grey number sequences on a two-dimensional surface,all the interval grey numbers are converted into real numbers by means of certain algorithm,and then the prediction model is established based on those real number *** entire process avoids the algebraic operations of grey number,and the prediction problem of interval grey number is usefully ***,through an example＇s program simulation,the validity and practicability of this novel model are verified.

关键词： grey system theory prediction model interval grey number grey number band grey number layer DGM(1 1) model.

Delay-dependent robust control for uncertain stochastic systems with Markovian switching and multiple delays

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journal of Systems Engineering and Electronics 2010年第2期21卷 287-295页

作者： Xudong zhao Mingxiang Ling Qingshuang zeng Space Control and Inertial Technology Institute Harbin Institute of Technology Harbin 150001 ER. China

The exponential stability in mean square and stabiliza- tion problems for It＆ stochastic switched systems with multiple time-delays are investigated. The system possesses the norm- bounded uncertainties and Markovian jumping parameters. By using an effective descriptor model transformation of the system and applying Ito＇s differential formula and Moon＇s inequality for bounding cross terms, a new delay-dependent sufficient condi- tion is derived in terms of linear matrix inequalities, and its states feedback controller is designed. Numerical examples are given to illustrate the efficiency and less conservation of the results.

关键词： stochastic systems Markovian jump time-delays lin- ear matrix inequalities.

Surface texture evaluation of additively manufactured metallic cellular scaffolds for acetabular implants using *** computed tomography

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Bio-Design and Manufacturing 2019年第2期2卷 55-64页

作者： Shan Lou Luca Pagani Wenhan zeng Muhammad U.Ghori Xiangqian jiang Paul j.Scott EPSRC Future Metrology Hub University of HuddersfieldQueensgateHuddersfield HD1 3DHUK Department of Pharmacy University of HuddersfieldQueensgateHuddersfield HD1 3DHUK

The surface topography of acetabular implants plays a key role in providing cell attachment and *** measurement and characterisation of the surface texture of the cellular scaffold layer on the acetabular cup are very difficult due to the 3D nature of scaffold *** is proposed to use X-ray computed tomography(XCT)to measure the surface texture of an electron beam melting-produced titanium acetabular *** surface texture of its cellular scaffold is evaluated using the newly developed 3D surface texture parameters,which allows surface characterisation on 3D triangular mesh *** commonly used height parameters,*** arithmetical mean height Sa,the root mean square height Sq,the skewness Ssk and the kurtosis Sku,are calculated from surface patches extracted from the XCT scanned triangular mesh *** addition,the surface peak density and pit density,which are more related to cell communication and proliferation,are estimated based on the 3D watershed *** Wolf pruning with an empirical threshold 12μm is used to control the over-segmentation.

关键词： Additive manufacturing Cellular scaffold Surface texture X-ray computed tomography

Using PoF models to predict system reliability considering failure collaboration

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Chinese journal of Aeronautics 2016年第5期29卷 1294-1301页

作者： zeng Zhiguo Kang Rui Chen yunxia Chair on Systems Science and Energetic Challenge Fondation Electricitéde France (EDF) Centrale Supélec Université Paris-Saclay School of Reliability and Systems Engineering Beihang University

Existing Physics-of-Failure-based （PoF-based） system reliability prediction methods are grounded on the independence assumption, which overlooks the dependency among the compo- nents. In this paper, a new type of dependency, referred to as failure collaboration, is introduced and considered in reliability predictions. A PoF-based model is developed to describe the failure behavior of systems subject to failure collaboration. Based on the developed model, the Bisection-based Reliability Analysis Method （BRAM） is exploited to calculate the system reliability. The developed methods are applied to predicting the reliability of a Hydraulic Servo Actuator （HSA）. The results demonstrate that the developed methods outperform the traditional PoF-based reliability prediction methods when applied to systems subject to failure collaboration.

关键词： Dependency Failure collaboration Physics-of-failure Reliability modeling Reliability prediction