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K介子协变动力学及其准粒子模型的性质
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作者 王艳艳 朱玉兰 +1 位作者 邢永忠 郑玉明 《原子核物理评论》 CAS CSCD 北大核心 2011年第4期408-415,共8页
简要综述了中高能重离子碰撞中K介子的产生及研究进展。重点介绍了K介子协变动力学模型,并在此框架内分析了中高能重离子碰撞中K+介子以及与其伴随产生的Λ超子的集体流特征。结果表明:协变动力学模型能够很好地给出K+介子和Λ超子的微... 简要综述了中高能重离子碰撞中K介子的产生及研究进展。重点介绍了K介子协变动力学模型,并在此框架内分析了中高能重离子碰撞中K+介子以及与其伴随产生的Λ超子的集体流特征。结果表明:协变动力学模型能够很好地给出K+介子和Λ超子的微分直接流。相对而言,软势给出的集体流与实验值符合更好。同时,通过对不同输运模型中K介子准粒子模型的基本属性进行对比分析,明确了协变动力学模型中K介子准粒子模型的质量及能量随核物质密度的变化特征,以及周围核子的运动对于K介子基本属性的影响。 展开更多
关键词 K介子 动力学 准粒子模型 基本属性
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Solution for Output Coordination Equations of Several Typical Parallel Six-Dimensional Acceleration Sensing Mechanisms
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作者 ZHANG Xianzhu YOU Jingjing ZHANG Yuanwei 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第S01期96-102,共7页
Aiming at the problem that it is difficult to generate the dynamic decoupling equation of the parallel six-dimensional acceleration sensing mechanism,two typical parallel six-dimensional acceleration sensing mechanism... Aiming at the problem that it is difficult to generate the dynamic decoupling equation of the parallel six-dimensional acceleration sensing mechanism,two typical parallel six-dimensional acceleration sensing mechanisms are taken as examples.By analyzing the scale constraint relationship between the hinge points on the mass block and the hinge points on the base of the sensing mechanism,a new method for establishing the dynamic equation of the sensing mechanism is proposed.Firstly,based on the scale constraint relationship between the hinge points on the mass block and the hinge points on the base of the sensing mechanism,the expression of the branch rod length is obtained.The inherent constraint relationship between the branches is excavated and the branch coordination closed chain of the“12-6”configuration is constructed.The output coordination equation of the sensing mechanism is successfully derived.Secondly,the dynamic equations of“12-4”and“12-6”configurations are constructed by the Newton-Euler method,and the forward decoupling equations of the two configurations are solved by combining the dynamic equations and the output coordination equations.Finally,the virtual prototype experiment is carried out,and the maximum reference errors of the forward decoupling equations of the two configuration sensing mechanisms are 4.23%and 6.53%,respectively.The results show that the proposed method is effective and feasible,and meets the real-time requirements. 展开更多
关键词 six-dimensional acceleration sensor parallel mechanism topological configuration coordination equation dynamics
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高性能分布式驱动电动汽车关键基础问题研究立项报告
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作者 余卓平 熊璐 《科技创新导报》 2016年第3期174-175,共2页
2009年我国汽车产销量突破1 370万辆,位居世界第一。汽车行业已成为我国现代装备制造业中的龙头产业,国民经济的重要支柱。但迅速增长的汽车保有量导致我国能源紧缺、环境污染与交通安全的问题也日益突出。发展电动汽车是解决上述问题... 2009年我国汽车产销量突破1 370万辆,位居世界第一。汽车行业已成为我国现代装备制造业中的龙头产业,国民经济的重要支柱。但迅速增长的汽车保有量导致我国能源紧缺、环境污染与交通安全的问题也日益突出。发展电动汽车是解决上述问题的有效途径。轮边驱动电动汽车则是电动汽车技术领域的重要发展方向。轮边驱动电动汽车将驱动电机分布安装于各驱动轮内或驱动轮附近,具有驱动传动链短、传动高效、结构紧凑等突出优点,能够有效降低车辆能耗;同时,轮边驱动电机动态响应快,有极佳的动力学控制性能,大幅提高车辆主动安全性能。轮边驱动电动汽车涉及机、电、液、热等多个领域,运行的环境与工况复杂,相关理论与技术还尚不成熟。因此,针对轮边驱动电动汽车围绕能耗优化与主动安全性控制开展的基础设计理论与关键技术的研究,对促进我国汽车工业的发展,具有极其重要的意义。该研究围绕"轮边驱动电动汽车复杂耦合系统动力学""多变环境与工况下轮边驱动电动汽车能耗规律""复杂工况下轮边驱动电动汽车耦合系统动力学协调控制机理"3个基础科学问题。该研究将建立基于轮边驱动电机特性的轮胎动态模型、车辆多体耦合动力学模型和动力电源—电驱动系统多场耦合动力学模型,构建轮边驱动电动汽车多体多场复杂耦合动力学系统;揭示电源与电驱动系统能耗规律、车辆空气/热动力学特性及其能耗规律,提出分布式电源与能量管理系统的分析与设计理论、车身造型及整车结构设计方法与整车热管理方法、无非驱动轮工况下车辆关键动力学参数自适应辨识方法、复杂耦合系统能耗优化与动力学协调控制理论,从而创立高性能轮边驱动电动汽车设计与控制的新理论、新方法。通过该重大基础研究项目的支持,将提高我国汽车工业的自主研发水平,为我国电动汽车开发提供基础理论支持,推动我国汽车工业的跨越式发展。 展开更多
关键词 分布式驱动电动汽车 耦合系统动力学 能耗规律 能量管理 空气与热动力学 状态估计 参数辨识 动力学协 调控
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Stabilization of Dynamic Systems for Multiple Omni-Directional Mobile Robots
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作者 王朝立 谈大龙 王越超 《Journal of Southeast University(English Edition)》 EI CAS 2001年第1期35-40,共6页
This paper deals with the stabilization of dynamic systems for two omni directional mobile robots by using the inner product of two vectors, one is from a robot's position to another's, the other is from a ro... This paper deals with the stabilization of dynamic systems for two omni directional mobile robots by using the inner product of two vectors, one is from a robot's position to another's, the other is from a robot's target point to another's. The multi step control laws given can exponentially stabilize the dynamic system and make the distance between two robots be greater than or equal to the collision free safe distance. The application of it to two omni directional mobile robots is described. Simulation result shows that the proposed controller is effective. 展开更多
关键词 omni directional mobile robot DYNAMICS COORDINATION collision avoidance STABILIZATION
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Hardware-in-loop Simulation(HLS) of Homing Anti-tank Missile 被引量:1
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作者 宋建梅 张天桥 《Journal of Beijing Institute of Technology》 EI CAS 1996年第1期49-54,共6页
The simulation techniques of hardware-in-loop simulation(HLS) of homing antitank missile based on the personal computer (PC) are discussed. The PC and MCS-96 chip controller employ A/D and D/A boards (with photoelectr... The simulation techniques of hardware-in-loop simulation(HLS) of homing antitank missile based on the personal computer (PC) are discussed. The PC and MCS-96 chip controller employ A/D and D/A boards (with photoelectricity isolation) to transfer measur ment and control information about homing head, gyro and rudder and utilize the digital hand shaking board to build correct communication communication protocol. In order to satisfy the real-time requirement of HLS, this paper first simplifies the aerodynamic data file reasonably, then builds a PC software with C language. The program of the controller part is made with PL/M language. The simulation of HLS based on PC is done with the same sampling period of 10ms as that of YH-F1 and the experiment results are identical to those of digital simulation of the homing anti-tank guided missile. 展开更多
关键词 HARDWARE-IN-LOOP SIMULATION communication protocol aerodynamic data
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Effect of Heat Stress on Photosynthetic Characteristics of Different Green Organs of Winter Wheat During Grain-filling Stage 被引量:28
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作者 徐晓玲 王志敏 张俊平 《Acta Botanica Sinica》 CSCD 2001年第6期571-577,共7页
Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag le... Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag leaf blade, nag leaf sheath, peduncle, glume, lemma and awn during grain-filling stage. The results showed that heat acclimation during grain-filling stage increased thermotolerance of wheat with significant differences among different green organs. During heat stress, the decreases of the efficiency of primary light energy conversion (F-v/F-m) of PS II and pigment (chlorophyll and carotenoid) content were much slower in peduncle, flag leaf sheath and glume than in nag leaf blade, lemma and ann; and the percentage of decrease in net photosynthetic rate (P-n) of ear was lower than that of the nag leaf blade. The measured photosynthetic parameters (F-v/F-m, P-n and pigment content) of 'JD 8', a relatively heat tolerant variety, declined more slowly than those of the other three varieties during the whole heat stress period. 展开更多
关键词 winter wheat net photosynthetic rate chlorophyll fluorescence kinetics parameters heat tolerance
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重离子碰撞中K+介子的横动能谱
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作者 邢永忠 思李飒娃德.彭拉德 郑玉明 《现代物理》 2014年第3期50-55,共6页
本文采用基于协变的K动力学的量子分子动力学模型,研究了1.93 AGeV入射能量的58Ni + 58Ni碰撞中产生的K+介子的横动能谱,并讨论了K+介子在介质中的位势对其横动能谱的影响。理论计算显示,只有计入K+介子在核介质中的位势的效应,才能合... 本文采用基于协变的K动力学的量子分子动力学模型,研究了1.93 AGeV入射能量的58Ni + 58Ni碰撞中产生的K+介子的横动能谱,并讨论了K+介子在介质中的位势对其横动能谱的影响。理论计算显示,只有计入K+介子在核介质中的位势的效应,才能合理地描写KaoS的实验数据。这表明,我们能从K+介子横动能谱的分析中提取出在核介质中K+介子位势的信息。同时,我们发现,K+介子的横动能谱也是一个探测核物态方程的敏感的观测量。 展开更多
关键词 重离子碰撞 K产生 横动能谱 在介质中的K+位势 核物态方程 变的K动力学 量子分子动力学模型
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Numerical Investigation on 1,3-Butadiene/Propyne Co-pyrolysis and Insight into Synergistic Effect on Aromatic Hydrocarbon Formation
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作者 李天宇 邹家标 +3 位作者 张言 曹创创 李伟 苑文浩 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2017年第3期287-294,I0001,共9页
A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation. A detailed kinetic model of 1,3-buta... A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation. A detailed kinetic model of 1,3-butadiene/propyne co-pyrolysis with the sub-mechanism of aromatic hydrocarbon formation is developed and validated on previous 1,3-butadiene and propyne pyrolysis experiments. The model is able to reproduce both the single component pyrolysis and the co-pyrolysis experiments, as well as the synergistic effect between 1,3- butadiene and propyne on the formation of a series of aromatic hydrocarbons. Based on the rate of production and sensitivity analyses, key reaction pathways in the fuel decomposition and aromatic hydrocarbon formation processes are revealed and insight into the synergistic effect on aromatic hydrocarbon formation is also achieved. The synergistic effect results from the interaction between 1,3-butadiene and propyne. The easily happened chain initiation in the 1,3-butadiene decomposition provides an abundant radical pool for propyne to undergo the H-atom abstraction and produce propargyl radical which plays key roles in the formation of aromatic hydrocarbons. Besides, the 1,3-butadiene/propyne co-pyrolysis includes high concentration levels of C3 and C4 precursors simultaneously, which stimulates the formation of key aromatic hydrocarbons such as toluene and naphthalene. 展开更多
关键词 1 3-BUTADIENE PROPYNE Kinetic model Synergistic effect Aromatic hydro-carbon formation
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Ion Pairing Kinetics Does not Necessarily Follow the Eigen-Tamm Mechanism 被引量:2
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作者 Qiang Zhang Bing-bing Zhang +1 位作者 Ling Jiang Wei Zhuang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第6期694-700,I0004,共8页
The most recognized and employed model of the solvation equilibration in the ionic solutions was proposed by Eigen and Tamm, in which there are four major states for an ion pair in the solution: the completely solvat... The most recognized and employed model of the solvation equilibration in the ionic solutions was proposed by Eigen and Tamm, in which there are four major states for an ion pair in the solution: the completely solvated state, 2SIP (double solvent separate ion pair), SIP (single solvent separate ion pair), and CIP (contact ion pair). Eigen and Tamm suggested that the transition from SIP to CIP is always the slowest step during the whole pairing process, due to a high free energy barrier between these two states. We carried out a series of potential of mean force calculations to study the pairing free energy profiles of two sets of model mono- atomic 1:1 ion pairs 2.0:x and x:2.0. For 2.0:x pairs the free energy barrier between the SIP and CIP states is largely reduced due to the salvation shell water structure. For these pairs the SIP to CIP transition is thus not the slowest step in the ion pair formation course. This is a deviation from the Eigen-Tamm model. 展开更多
关键词 Ion pairing Eigen-Tamm model Potential of mean force
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Solar-heating boosted catalytic reduction of CO_(2) under full-solar spectrum 被引量:2
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作者 Hongjia Wang Yanjie Wang +3 位作者 Lingju Guo Xuehua Zhang Caue Ribeiro Tao He 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第1期131-139,共9页
Catalytic converting CO2 into fuels with the help of solar energy is regarded as‘dream reaction’,as both energy crisis and environmental issue can be mitigated simultaneously.However,it is still suffering from low e... Catalytic converting CO2 into fuels with the help of solar energy is regarded as‘dream reaction’,as both energy crisis and environmental issue can be mitigated simultaneously.However,it is still suffering from low efficiency due to narrow solar-spectrum utilization and sluggish heterogeneous reaction kinetics.In this work,we demonstrate that catalytic reduction of CO2 can be achieved over Au nanoparticles(NPs)deposited rutile under full solar-spectrum irradiation,boosted by solar-heating effect.We found that UV and visible light can initiate the reaction,and the heat from IR light and local surface-plasmon resonance relaxation of Au NPs can boost the reaction kinetically.The apparent activation energy is determined experimentally and is used to explain the superior catalytic activity of Au/rutile to rutile in a kinetic way.We also find the photo-thermal synergy in the Au/rutile system.We envision that this work may facilitate understanding the kinetics of CO2 reduction and developing feasible catalytic systems with full solar spectrum utilization for practical artificial photosynthesis. 展开更多
关键词 CO_(2) reduction Apparent activation energy Reaction kinetics Solar heating Photo-thermal synergy
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Kinetic, electronic properties and conductivity studies of ((12Z)N-(5Z)-1-bromo-5-(phenylimino)-1H-pyrrol-2(5H)-ylidene benzenmine {ArN(CNBrCCHCH)NAr} (Ar = C6H5) 被引量:1
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作者 Salem Et. Ashoor Noori Y. Salman 《Journal of Chemistry and Chemical Engineering》 2009年第10期51-56,共6页
Kinetic and conductivity of new Schiff bases compounds such ((12Z)N-(5Z)-1-bromo-5-(phenylimino)-1H- pyrrol-2(5 H)-ylidene)benzenamine {ArN(CNBrCCHCH)NAr} (Ar = C6H5) incorporating the chelating diamino ... Kinetic and conductivity of new Schiff bases compounds such ((12Z)N-(5Z)-1-bromo-5-(phenylimino)-1H- pyrrol-2(5 H)-ylidene)benzenamine {ArN(CNBrCCHCH)NAr} (Ar = C6H5) incorporating the chelating diamino has been studied in this paper and was found a second order of this reaction. Electronic Properties using hyperchem program study has been improved for this compound such angel and bond distance, and then this compound was defining as electric conductivity and did prove to be useful for conduclively compound. 展开更多
关键词 Schiff bases compounds ((12Z)N-(5Z)-1-bromo-5-(phenylimino)- 1H-pyrrol-2(5H)-ylide ne)benzenamine chelating diamino: electronic properties
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Cooperative Effects of Noise and Coupling on Stochastic Dynamics of a Membrane-Bulk Coupling Model
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作者 TANG Jun JIA Ya YI Ming 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第3期455-459,共5页
Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 (2007) 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated. ... Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 (2007) 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated. For parameters in a certain region, the oscillation can be induced by the cooperative effect of noise and coupling. Whether considering the coupling or not, corresponding coherence resonance phenomena are observed. Furthermore, the effects of two coupling parameters, cell size L and coupling intensity k, on the noise-induced oscillation of membranes are studied. Contrary effects of noise are found in and out of the deterministic oscillatory regions. 展开更多
关键词 membrane-bulk cell model COUPLING noise coherence resonance
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Implementing 1 → M Economical Phase-Covariant Telecloning in Cavity QED
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作者 XUE Li JIANG Nian-Quan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第3期441-444,共4页
We propose an experimentally feasible scheme to implement the economical 1 → M phase-covariant telecloning based on cavity QED. By the resonant interaction of the atoms with cavity field of a high-Q cavity and the di... We propose an experimentally feasible scheme to implement the economical 1 → M phase-covariant telecloning based on cavity QED. By the resonant interaction of the atoms with cavity field of a high-Q cavity and the different coupling strength between atoms and cavity field, the scheme can generate quantum entanglement channel in one step. What is more, the operation time and steps do not increase with the increase of atoms. 展开更多
关键词 cavity QED phase-covariant telecloning
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Static-deformation based fault diagnosis for damping spring of large vibrating screen 被引量:7
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作者 彭利平 刘初升 +1 位作者 李珺 王宏 《Journal of Central South University》 SCIE EI CAS 2014年第4期1313-1321,共9页
Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the st... Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS. 展开更多
关键词 static deformation suspended mass method large vibrating screen damping spring fault diagnosis
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Driving Factors of Coordinated Development in Chinese Border Cities:A Case Study of Lincang City in Southwest China
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作者 XU Bingjie YOU Zhen +4 位作者 FENG Zhiming LIAN Chenqin QI Wei YOU Shiqing FAN Feifei 《Journal of Resources and Ecology》 CSCD 2024年第4期951-965,共15页
In the context of the“Belt and Road Initiative”,the sustainable development of border cities is paramount for facilitating intergovernmental exchanges.Using the system dynamics approach,we integrated border policy f... In the context of the“Belt and Road Initiative”,the sustainable development of border cities is paramount for facilitating intergovernmental exchanges.Using the system dynamics approach,we integrated border policy factors to create the Border City Coordinated Development(BCCD-SD)model,encompassing three dimensions:Economic,Social,and Resource-Environment.Furthermore,a comprehensive evaluation indicator,the City Coordinated Development Index(CCDI),was devised.Using Lincang City in Southwest China as a case study,this article examines the trends in city development under three scenarios:Inertial Development,Rapid Development,and Green Development.The research findings demonstrate that the model adeptly captures trends in the city coordinated development indicators.Among the three scenarios,the rapid development scenario stands out,yielding the most favorable economic indicators,superior public infrastructure,and the highest employed population.However,the rapid development path,which is heavily focused on economic growth,intensifies resource and environmental pressures,giving rise to sustainability challenges.In contrast,although the green development scenario trails slightly in economic performance compared to rapid development,it fosters a larger urban population and transition of the employed population into citizens while excelling in resource and environmental aspects.Overall,the CCDI attains its highest score under the green development scenario,surpassing those of rapid and inertia development,signifying superior city development coordination along the green path.This scenario effectively combines economic growth,social progress,and resource-environment protection.This study also emphasizes the pivotal role of ports in the coordinated development of border cities and underscores the necessity of expediting the transition from a“gateway”economy to a“port+”economy.One objective of this article is to encourage border cities to serve as more effective windows to the outside world,promote regional coordination,and achieve high-quality development. 展开更多
关键词 system dynamics Lincang City coordinated development border policy Southwest China border
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Optimal multi-objective trajectory design based on close-looped control for autonomous rendezvous 被引量:6
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作者 LI JiuRen LI HaiYang TANG GuoJin 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第11期3091-3097,共7页
This paper considers the problem of optimal multi-objective trajectory design for autonomous rendezvous. Total velocity cost and relative state robustness of close-looped control are selected as the objective function... This paper considers the problem of optimal multi-objective trajectory design for autonomous rendezvous. Total velocity cost and relative state robustness of close-looped control are selected as the objective functions. Based on relative dynamics equations, the state equations and measurement equations for angles-only relative navigation between spacecraffs are set forth. According to the method of linear covariance analysis, the close-looped control covariance of the true relative state from the reference relative state is analyzed, and the objective functions of relative state robustness are formulated. Considering the total velocity cost and the relative state robustness, the multi-objective optimization algorithm of NSGA-II is employed to solve this multi-impulsive rendezvous problem. Lastly, the validity of the objective functions and the covariance results are demonstrated through 1 00 times Monte Carlo simulation. 展开更多
关键词 autonomous rendezvous relative navigation close-looped control MULTI-OBJECTIVE ROBUSTNESS
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CFD Study on Local Fluid-to-Wall Heat Transfer in Packed Beds and Field Synergy Analysis 被引量:4
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作者 PENG Wenping XU Min +1 位作者 HUAI Xiulan LIU Zhigang 《Journal of Thermal Science》 SCIE EI CAS CSCD 2016年第2期161-170,共10页
To reach the target of smaller pressure drop and better heat transfer performance, packed beds with small tube-to-particle diameter ratio(D/dp<10) have now been considered in many areas. Fluid-to-wall heat transfer... To reach the target of smaller pressure drop and better heat transfer performance, packed beds with small tube-to-particle diameter ratio(D/dp<10) have now been considered in many areas. Fluid-to-wall heat transfer coefficient is an important factor determining the performance of this type of beds. In this work, local fluid-to-wall heat transfer characteristic in packed beds was studied by Computational Fluid Dynamics(CFD) at different Reynolds number for D/dp=1.5, 3.0 and 5.6. The results show that the fluid-to-wall heat transfer coefficient is oscillating along the bed with small tube-to-particle diameter ratio. Moreover, this phenomenon was explained by field synergy principle in detail. Two arrangement structures of particles in packed beds were recommended based on the synergy characteristic between flow and temperature fields. This study provides a new local understanding of fluid-to-wall heat transfer in packed beds with small tube-to-particle diameter ratio. 展开更多
关键词 Packed bed Fluid-to-wall heat transfer Field synergy principle Computational fluid dynamics Heat transfer intensification
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Modified Nonlinear Model of Arcsin-Electrodynamics
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作者 S.I.Kruglov 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第7期59-65,共7页
A new modified model of nonlinear arcsin-electrodynamics with two parameters is proposed and analyzed.We obtain the corrections to the Coulomb law. The effect of vacuum birefringence takes place when the external cons... A new modified model of nonlinear arcsin-electrodynamics with two parameters is proposed and analyzed.We obtain the corrections to the Coulomb law. The effect of vacuum birefringence takes place when the external constant magnetic field is present. We calculate indices of refraction for two perpendicular polarizations of electromagnetic waves and estimate bounds on the parameter γ from the BMV and PVLAS experiments. It is shown that the electric field of a point-like charge is finite at the origin. We calculate the finite static electric energy of point-like particles and demonstrate that the electron mass can have the pure electromagnetic nature. The symmetrical Belinfante energy-momentum tensor and dilatation current are found. We show that the dilatation symmetry and dual symmetry are broken in the model suggested. We have investigated the gauge covariant quantization of the nonlinear electrodynamics fields as well as the gauge fixing approach based on Dirac's brackets. 展开更多
关键词 vacuum birefringence energy-momentum tensor static electric energy dilatation current dual symmetry quantization Dirac's brackets
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The principle of compromise in competition: exploring stability condition of protein folding 被引量:1
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作者 徐骥 韩孟之 +1 位作者 任瑛 李静海 《Science Bulletin》 SCIE EI CAS CSCD 2015年第1期76-85,共10页
Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows ... Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows that some proteins have even lower free energy in inter- mediate states and their native states are kinetically trapped in the higher free energy region. This article explores the stability condition of protein structures on the basis of our study of complex chemical systems. We believe that sep- arating one from another is not reasonable since they should be coupled, and protein structures should be dom- inated by at least two mechanisms resulting in different characteristic states. It is concluded that: (1) Structures of proteins are dynamic, showing multiple characteristic states emerging alternately and each dominated by a respective mechanism. (2) Compromise in competition of multiple dominant mechanisms might be the key to understanding the stability of protein structures. (3) The dynamic process of protein folding should be depicted through the time series of both its energetic and structural changes, which is much meaningful and applicable than the free energy landscape. 展开更多
关键词 Protein folding Dynamic structure -Multiple mechanisms Compromise in competitionMesoscale STABILITY
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Tectonomicrobiology:A new paradigm for geobiological research 被引量:1
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作者 Chuanlun ZHANG Jian LIN +3 位作者 Sanzhong LI Hailiang DONG Fengping WANG Shucheng XIE 《Science China Earth Sciences》 SCIE EI CAS CSCD 2018年第4期494-498,共5页
Geomicrobiology is a sub-discipline of geobiology and emphasizes the interaction between microorganisms and their environment on Earth. There is a need to explicitly emphasize the biogeochemical processes performed by... Geomicrobiology is a sub-discipline of geobiology and emphasizes the interaction between microorganisms and their environment on Earth. There is a need to explicitly emphasize the biogeochemical processes performed by microorganisms associated with Earth's tectonic activities, especially under the framework of the modern theory of plate tectonics. Tectonomicrobiology aims to create a better synergy between microbial and active tectonic processes. This explicit synergy should also foster better communications between solid Earth scientists and life scientists in terms of holistic Earth system dynamics at both tectonic and micro-scales. 展开更多
关键词 Geobiology Geomicrobiology Tectonomicrobiology Tectonic activities Microbial evolution
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