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Ideal Strengths and Bonding Properties of PuO_(2)under Tension

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Chinese Physics Letters 2011年第4期28卷 178-181页

作者： wang bao-Tian ZHANG Ping Institute of Theoretical Physics and the Department of Physics Shanxi UniversityTaiyuan 030006 LCP Institute of Applied Physics and Computational MathematicsBeijing 100088

We perform a first-principles computational tensile test on PuO_(2)based on density-functional theory within a local density approximation(LDA)+U formalism to investigate its structural,mechanical,magnetic and intrinsic bonding properties in four representative directions:[001],[100],[110]and[111].The stress-strain relations show that the ideal tensile strengths in the four directions are 81.2,80.5,28.3 and 16.8 GPa at strains of 0.36,0.36,0.22 and 0.18,***[001]and[100]directions are prominently stronger than the other two directions since more Pu-0 bonds participate in the pulling *** charge and density of state analysis along the[001]direction,we find that the strong mixed ioni%ovalent character of the Pu-0 bond is weakened by tensile strain and PuO_(2)will exhibit an insulator-to-metal transition after tensile stresses exceeding about 79 GPa.

关键词： process strain directions

Multi-Physics Modeling of Solid Oxide Fuel Cell Fueled by Methane and Analysis of Carbon Deposition

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Chinese Journal of Chemical Physics 2015年第3期28卷 299-307,I0001页

作者： bao-xuan wang Jiang Zhu Zi-jing Lin Hefei National Laboratory for Physical Sciences at the Microscale & Collaborative Innovation Center of Suzhou Nano Science and Technology University of Science and Technology of China Hefei 230025 China Key Laboratory of Strongly-Coupled Quantum Matter Physics Chinese Academy of Sciences and Department of Physics University of Science and Technology of China Hefei 230025 China

Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.

关键词： Numerical model Methane reforming kinetics Current-voltage relation Carbon activity Diffusion barrier layer

Effect of cross wedge rolling on the microstructure of GH4169 alloy

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International Journal of Minerals,Metallurgy and Materials 2012年第9期19卷 836-842页

作者： Ning Zhang bao-yu wang Jian-guo Lin School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China Deparment of Mechanical Engineering Imperial College London SW7 2AZ UK

The metal microstructure during the hot forming process has a significant effect on the mechanical properties of final products. To study the microstructural evolution of the cross wedge rolling （CWR） process, the microstructural model of GH4169 alloy was programmed into the user subroutine of DEFORM-3D by FORTRAN. Then, a coupled thermo-mechanical and microstructural simulation was performed under different conditions of CWR, such as area reduction, rolling temperature, and roll speed. Comparing experimental data with simulation results, the difference in average grain size is from 11.2% to 33.4% so it is verified that the mierostructural model of GH4169 alloy is reliable and accurate. The fine grain of about 12-15 p.m could be obtained by the CWR process, and the grain distribution is very homogeneous. For the symmetry plane, increasing the area reduction is helpful to refine the grain and the value should be around 61%. Moreover, when the roiling temperature changes from 1000 to 1100℃ and the roll speed from 6 to 10 ***-1, the grain size of the rolled piece decreases first and then increases. The temperature may be better to choose the value around 1050℃ and the speed less than 10 r-min-1.

关键词： superalloys nickel alloys cross wedge rolling microstructural evolution grain size numerical analysis

Moving target defense:state of the art and characteristics

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Frontiers of Information Technology & Electronic Engineering 2016年第11期17卷 1122-1153页

作者： Gui-lin CAI bao-sheng wang Wei HU Tian-zuo wang College of Computer National University of Defense Technology

Moving target defense(MTD) has emerged as one of the game-changing themes to alter the asymmetric situation between attacks and defenses in cyber-security. Numerous related works involving several facets of MTD have been published. However, comprehensive analyses and research on MTD are still absent. In this paper, we present a survey on MTD technologies to scientifically and systematically introduce, categorize, and summarize the existing research works in this field. First, a new security model is introduced to describe the changes in the traditional defense paradigm and security model caused by the introduction of MTD. A function-and-movement model is provided to give a panoramic overview on different perspectives for understanding the existing MTD research works. Then a systematic interpretation of published literature is presented to describe the state of the art of the three main areas in the MTD field, namely, MTD theory, MTD strategy, and MTD evaluation. Specifically,in the area of MTD strategy, the common characteristics shared by the MTD strategies to improve system security and effectiveness are identified and extrapolated. Thereafter, the methods to implement these characteristics are concluded. Moreover, the MTD strategies are classified into three types according to their specific goals, and the necessary and sufficient conditions of each type to create effective MTD strategies are then summarized, which are typically one or more of the aforementioned characteristics. Finally, we provide a number of observations for the future direction in this field, which can be helpful for subsequent researchers.

关键词： Moving target defense Security model Function-and-movement model Characteristics

Kalman Filtering with Partial Markovian Packet Losses

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International Journal of Automation and computing 2009年第4期6卷 395-400页

作者： bao-Feng wang Ge Guo School of Information Science and Technology Dalian Maritime University Dalian 116026 PRC

We consider the Kalman filtering problem in a networked environment where there are partial or entire packet losses described by a two state Markovian process. Based on random packet arrivals of the sensor measurements and the Kalman filter updates with partial packet, the statistical properties of estimator error covariance matrix iteration and stability of the estimator are studied. It is shown that to guarantee the stability of the Kalman filter, the communication network is required to provide for each of the sensor measurements an associated throughput, which captures all the rates of the successive sensor measurements losses. We first investigate a general discrete-time linear system with the observation partitioned into two parts and give sufficient conditions of the stable estimator. Furthermore, we extend the results to a more general case where the observation is partitioned into n parts. The results are illustrated with some simple numerical examples.

关键词： Networked control systems partial packet losses Markovian packet losses stability

Soliton Molecules and Some Hybrid Solutions for the Nonlinear Schrodinger Equation

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Chinese Physics Letters 2020年第3期37卷 9-12页

作者： bao wang Zhao Zhang Biao Li Robotics Institute Ningbo University of TechnologyNingbo 315211 School of Mathematics and Statistics Ningbo UniversityNingbo 315211

Based on velocity resonance and Darboux transformation,soliton molecules and hybrid solutions consisting of soliton molecules and smooth positons are *** new interesting results are obtained:the first is that the relationship between soliton molecules and smooth positons is clearly pointed out,and the second is that we find two different interactions between smooth positons called strong interaction and weak interaction,*** strong interaction will only disappear when t→∞.This strong interaction can also excite some periodic phenomena.

关键词： soliton interaction Nonlinear

One-step fabrication superhydrophobic sand filter for capillary-driven separation of water-in-oil emulsions

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Chinese Journal of Chemical Engineering 2021年第5期34卷 70-75页

作者： bao wang Chaolang Chen Zhaoxin Li Jianfeng Wu Xianglou Liu Jiadao wang Northeast Petroleum University Daqing 163318China Sate Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

The efficient separation of water-in-oil emulsion is of significance in environment and energy filed,and it has become a world-wide ***,we have presented a one-step,facile and low-cost approach to prepare superhydrophobic sands for efficient separation of water-in-oil *** as-prepared sand layers possessed a water contact angle higher than 151°,demonstrating their superior superhydrophobic ***,the as-prepared sand layers could separate water-in-emulsions with separation efficiency up to 99.7%,which is superior to both traditional and superwettable filtration *** effect of thickness of sand layer on separation performance was also *** results showed that the filtration flux decreased with the increased of filtration thickness while the separation efficiency *** as-prepared sand layer proposed by this study is a processing candidate for separating water-in-oil emulsion in practical ***,the as-prepared superhydrophobic sand fabrication method also provides an alternative for desert water storage.

关键词： Separation Filtration Superhydrophobic sand Preparation Emulsion

Precise Large Deviations for Sums of Negatively Associated Random Variables with Common Dominatedly Varying Tails

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Acta Mathematica Sinica,English Series 2006年第6期22卷 1725-1734页

作者： Yue bao wang Kai Yong wang Dong Ya CHENG School of Mathematics Science Soochow University Suzhou 215006 P. R. China Department of Applied Mathematics University of Science and Technology of Suzhou Suzhou 215009 P. R. China

In this paper, we obtain results on precise large deviations for non-random and random sums of negatively associated nonnegative random variables with common dominatedly varying tail distribution function. We discover that, under certain conditions, three precise large-deviation prob- abilities with different centering numbers are equivalent to each other. Furthermore, we investigate precise large deviations for sums of negatively associated nonnegative random variables with certain negatively dependent occurrences. The obtained results extend and improve the corresponding results of Ng, Tang, Yan and Yang （J. Appl. Prob., 41, 93-107, 2004）.

关键词： negatively associated dominatedly varying tail precise large deviation

Catalysis Conversion Methane into C_(2) Hydrocarbons via Electric Field Enhanced Plasma

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Chinese Chemical Letters 2003年第12期14卷 1236-1238页

作者： bao Wei wang Gen Hui XU State Key Laboratory of C1 Chemistry and Technology Tianjin UniversityTianjin 300072

In this paper the effect of catalyst and carrier in electric field enhanced plasma on methane conversion into C2 hydrocarbons was investigated. Methane coupling reaction was studied in the system of continuous flow reactor on Ni, MoO3, MnO2 catalysts and different ZSM-5 carriers. The per pass conversion of methane can be as high as 22%, the selectivity of ethylene can be as high as 23.8%, of acetylene 60.8%, of ethane 5.4% and of total C2 hydrocarbons was more than 90%. ZSM-5-25 was the better carrier and MnO2 was the better active component. The efficiency of energy was as high as 7.81%.

关键词： Methane electric field enhanced plasma catalysis C_(2) hydrocarbons.