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Phase–amplitude model for doubly fed induction generators 预览
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作者 Hua HUANG Ping JU +3 位作者 Xueping PAN Yuqing JIN Xiaoming YUAN Yuan GAO 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第2期369-379,共11页
The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power sys... The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power system dynamics. However, most existing practical models of the DFIG are based on rectangular coordinates,in which frequency variation is neglected. In this paper, a phase-amplitude(P-A) model is proposed for a DFIG based on phase and amplitude of the internal voltage. The model structure is much like that of the synchronous generator, and the rotor voltage can manipulate both the amplitude and the phase of the internal voltage.Comparisons have been made between the new P-A model of the DFIG and the synchronous generator model,as well as the asynchronous motor model.The contributions of the new P-A model of the DFIG are discussed and it is demonstrated that the proposed model has better ability in describing power system dynamic phenomena such as voltage dynamics and structural dynamics. Simulation results and a field test validate these contributions. 展开更多
关键词 DOUBLY fed induction generator(DFIG) MODEL Internal VOLTAGE VOLTAGE DYNAMICS Frequency DYNAMICS
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Glassy dynamics of water at interface with biomolecules:A Mode Coupling Theory test
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作者 Antonio Iorio Gaia Camisasca Paola Gallo 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS CSCD 2019年第10期82-86,共5页
We study the slow dynamics of hydration water upon cooling in two different biological aqueous solutions,one containing a molecule of lysozyme and another with trehalose molecules.In particular we test if the glassy b... We study the slow dynamics of hydration water upon cooling in two different biological aqueous solutions,one containing a molecule of lysozyme and another with trehalose molecules.In particular we test if the glassy behaviour of these solutions fulfils the predictions of the popular Mode Coupling Theory of glassy dynamics.In particular we test the Time Temperature Superposition Principle and the matching of the exponents of the theory.Our results confirm that this theory is able to describe the dynamical behaviour of supercooled water also in non ideal cases as the ones under investigation in the region of mild supercooling. 展开更多
关键词 GLASSY DYNAMICS AQUEOUS SOLUTIONS biomolecules MOLECULAR DYNAMICS
Time-scale separation and stochasticity conspire to impact phenotypic dynamics in the canonical and inverted Bacillus subtilis core genetic regulation circuits
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作者 Lijie Hao Zhuoqin Yang Marc Turcotte 《中国电气与电子工程前沿:英文版》 CSCD 2019年第1期54-68,共15页
Backgrounds In this work, we study two seemingly unrelated aspects of core genetic nonlinear dynamical control of the competence phenotype in Bacillus subtilis, a common Gram-positive bacterium living in the soil. Met... Backgrounds In this work, we study two seemingly unrelated aspects of core genetic nonlinear dynamical control of the competence phenotype in Bacillus subtilis, a common Gram-positive bacterium living in the soil. Methods: We focus on hitherto unchartered aspects of the dynamics by exploring the effect of time-scale separation between transcription and translation and, as well, the effect of intrinsic molecular stochasticity. We consider these aspects of regulatory control as two possible evolutionary handles. Results: Hence, using theory and computations, we study how the onset of oscillations breaks the excitability-based competence phenotype in two topologically close evolutionary-competing circuits: the canonical "wild-type" regulation circuit selected by Evolution and the corresponding indirect-feedback inverted circuit that failed to be selected by Evolution, as was shown elsewhere, due to dynamical reasons. Conclusions^ Relying on in-silico perturbation of the living state, we show that the canonical core genetic regulation of excitability-based competence is more robust against switching to phenotype-breaking oscillations than the inverted feedback organism. We show how this is due to time-scale separation and stochasticity. 展开更多
关键词 Bacillus SUBTILIS competence gene regulation deterministic DYNAMICS stochastic DYNAMICS
Combining Neutron Scattering, Deuteration Technique, and Molecular Dynamics Simulations to Study Dynamics of Protein and Its Surface Water Molecules
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作者 Li-Rong Zheng Liang Hong 《高分子科学:英文版》 SCIE CAS CSCD 2019年第11期1083-1091,共9页
Protein internal dynamics is essential for its function. Exploring the internal dynamics of protein molecules as well as its connection to protein structure and function is a central topic in biophysics. However, the ... Protein internal dynamics is essential for its function. Exploring the internal dynamics of protein molecules as well as its connection to protein structure and function is a central topic in biophysics. However, the atomic motions in protein molecules exhibit a great degree of complexities. These complexities arise from the complex chemical composition and superposition of different types of atomic motions on the similar time scales, and render it challenging to explicitly understand the microscopic mechanism governing protein motions, functions, and their connections. Here, we demonstrate that, by using neutron scattering, molecular dynamics simulation, and deuteration technique, one can address this challenge to a large extent. 展开更多
关键词 NEUTRON scattering DEUTERATION techniques Molecular DYNAMICS simulations Protein HYDRATION water DYNAMICS
Flight dynamics characteristics of canard rotor/wing aircraft in helicopter flight mode
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作者 Honggang GAO Ao HE +2 位作者 Zhenghong GAO Yang NA Yangping DENG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第7期1577-1587,共11页
The aerodynamic layout of the Canard Rotor/Wing(CRW) aircraft in helicopter flight mode differs significantly from that of conventional helicopters. In order to study the flight dynamics characteristics of CRW aircraf... The aerodynamic layout of the Canard Rotor/Wing(CRW) aircraft in helicopter flight mode differs significantly from that of conventional helicopters. In order to study the flight dynamics characteristics of CRW aircraft in helicopter mode, first, the aerodynamic model of the main rotor system is established based on the blade element theory and wind tunnel test results. The aerodynamic forces and moments of the canard wing, horizontal tail, vertical tail and fuselage are obtained via theoretical analysis and empirical formula. The flight dynamics model of the CRW aircraft in helicopter mode is developed and validated by flight test data. Next, a method of model trimming using an optimization algorithm is proposed. The flight dynamics characteristics of the CRW are investigated by the method of linearized small perturbations via Simulink. The trim results are consistent with the conventional helicopter characteristics, and the results show that with increasing forward flight speed, the canard wing and horizontal tail can provide considerable lift,which reflects the unique characteristics of the CRW aircraft. Finally, mode analysis is implemented for the linearized CRW in helicopter mode. The results demonstrate that the stability of majority modes increases with increasing flight speed. However, one mode that diverges monotonously,and the reason is that the CRW helicopter mode has a large vertical tail compared to the conventional helicopter. The results of the dynamic analysis provide optimization guidance and reference for the overall design of the CRW aircraft in helicopter mode, and the model developed can be used for control system design. 展开更多
关键词 CANARD rotor/wing AIRCRAFT DYNAMICS analysis FLIGHT DYNAMICS HELICOPTER LINEARIZATION Model building
Recent advances in physical understanding and quantitative prediction of impinging-jet dynamics and atomization
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作者 Xiaodong CHEN Vigor YANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第1期45-57,共13页
Impinging-jet injectors are widely used in liquid propulsion applications, since their simple configuration provides reliable and efficient atomization. The flowfield involves a series of complicated spatio-temporal e... Impinging-jet injectors are widely used in liquid propulsion applications, since their simple configuration provides reliable and efficient atomization. The flowfield involves a series of complicated spatio-temporal evolutions. Much effort has been directed toward understanding the underlying physics and developing quantitative predictions of impinging-jet atomization. This paper summarizes the recent advances in this direction, including state-of-the-art theoretical, experimental, and numerical studies, along with representative results. Finally, concluding remarks address remaining challenges and highlight modeling capabilities of high-fidelity simulations. 展开更多
关键词 Computational fluid DYNAMICS FLOW instability FLOW visualization Gas/liquid interfacial DYNAMICS Impinging-jet ATOMIZATION Theoretical models Two-phase FLOW
SCARA并联机构刚度和动力学分析 预览
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作者 朱伟 郭倩 +2 位作者 马致远 沈惠平 吴广磊 《农业机械学报》 EI CAS CSCD 北大核心 2019年第10期375-385,共11页
阐述了一种由2条RSS支链和2条R(SRS)2R支链构成,可实现SCARA运动的新型四自由度高速并联机器人机构。首先,采用方位特征理论(POC)分析了该机构的拓扑结构特征,用矢量法求解了位置反解;其次,运用虚拟弹簧法建立了支链的刚度模型,并求解... 阐述了一种由2条RSS支链和2条R(SRS)2R支链构成,可实现SCARA运动的新型四自由度高速并联机器人机构。首先,采用方位特征理论(POC)分析了该机构的拓扑结构特征,用矢量法求解了位置反解;其次,运用虚拟弹簧法建立了支链的刚度模型,并求解了支链的静力学方程;再次,利用旋量法得到支链中虚拟关节变形到末端变形的微分映射,从而求得机构的笛卡尔刚度矩阵,根据机构的转动和移动刚度性能指标,分别分析了机构在不同工作平面的刚度特性。最后,推导了机构的主动臂、从动臂和动平台速度、加速度方程,并运用虚功原理建立了机构的动力学模型,通过ADAMS三维模型仿真验证了动力学模型的正确性,为该机构的进一步研究及实际应用奠定了理论基础。 展开更多
关键词 SCARA并联机构 虚拟弹簧 刚度 动力学
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华北克拉通北缘西段宝音图群片岩中石榴子石变斑晶成分特征及其动力学意义
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作者 闫岩 彭润民 +1 位作者 陈思雨 陆彬 《矿物岩石地球化学通报》 CAS CSCD 北大核心 2019年第3期559-571,共13页
石榴子石变斑晶微结构和成分特征对构造和变质作用研究有重要作用。本文以华北克拉通北缘西段宝音图群石榴子石云母片岩中的石榴子石变斑晶为研究对象,通过扫描电子显微镜搭载的二次电子(SE)显微结构形貌观测,背散射电子(BSE)成分分析... 石榴子石变斑晶微结构和成分特征对构造和变质作用研究有重要作用。本文以华北克拉通北缘西段宝音图群石榴子石云母片岩中的石榴子石变斑晶为研究对象,通过扫描电子显微镜搭载的二次电子(SE)显微结构形貌观测,背散射电子(BSE)成分分析、能谱仪(EDS)和电子探针(EPMA)分析,得到石榴子石变斑晶组构和化学成分信息,揭示出石榴子石晶界具有化学非均质性。在MnNCFMASHO体系下采用石榴子石云母石英片岩的全岩成分计算的锰铝榴石、钙铝榴石等值线图基础上,建立了石榴子石变斑晶的p-t轨迹,反映出石榴子石变斑晶在变质峰期后经历了一个近等温降压的地质动力学过程。 展开更多
关键词 石榴子石变斑晶 化学成分 动力学 华北克拉通
数字孪生驱动的工业园区“产—运—存”联动决策架构、模型与方法 预览
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作者 周达坚 屈挺 +4 位作者 张凯 郭洪飞 闫勉 李从东 黄国全 《计算机集成制造系统》 EI CSCD 北大核心 2019年第6期1576-1590,共15页
小批量及定制化生产模式下,由资源、流程不确定性引发的复杂动态生产环境对大型多单元生产系统的运行控制精度提出了更高的要求。如何面向随机产生的动态性,对生产单元的执行状态进行精准建模与实时反映,并通过多单元在线联动决策实现... 小批量及定制化生产模式下,由资源、流程不确定性引发的复杂动态生产环境对大型多单元生产系统的运行控制精度提出了更高的要求。如何面向随机产生的动态性,对生产单元的执行状态进行精准建模与实时反映,并通过多单元在线联动决策实现对系统的适应性、迭代式、精细化管控来支持各环节高效协同运作是大型多单元生产物流系统过程控制的关键挑战。以工业园区'产—运—存'三类典型单元的实时联动运作为研究对象,在数字孪生的框架下,提出跨单元的数字孪生联动决策信息架构:通过'物理环境—虚拟模型'的动态精准映射与实时反馈控制,并采用目标级联法对虚拟层中多个具有独立决策且联动运作的'产—运—存'决策单元以全局优化、分布控制的模式进行系统性协调,实现大型系统的在线联动决策。最后以某大型化工生产企业的多单元联动生产过程为例,基于其实际生产数据对所建立的联动决策模型及目标级联法定量联动方法进行仿真和对比分析,结果表明所提方法能够有效实现多单元同步运作,减少生产总成本和订单在库时间。 展开更多
关键词 数字孪生 工业园区 协同决策 联动控制 动态性 化工生产企业
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小麦开花后籽粒多组分营养物质积累动态分析 预览
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作者 梁勇 陈月星 +3 位作者 甘琴 程剑平 赵钢 严俊 《种子》 北大核心 2019年第1期13-18,24共7页
为探究小麦开花后籽粒中多组分营养物质积累的动态规律及其相互间的关系,本研究以六倍体栽培小麦中国春和贵紫1号为材料,对开花后10、15、20、25、30、35、40d的籽粒总类黄酮、总酚、植酸、无机磷、总淀粉、氨基和可溶性蛋白质含量及单... 为探究小麦开花后籽粒中多组分营养物质积累的动态规律及其相互间的关系,本研究以六倍体栽培小麦中国春和贵紫1号为材料,对开花后10、15、20、25、30、35、40d的籽粒总类黄酮、总酚、植酸、无机磷、总淀粉、氨基和可溶性蛋白质含量及单粒重进行了动态测定及单因素方差(One-Way ANOVA)、相关性网络(Correlation-based network analysis,CAN)和斯皮尔曼秩相关(Spearmanp’s Rho Correlation)等分析。结果表明,在籽粒发育过程中,氨基、可溶性蛋白质以及无机磷含量逐渐降低,淀粉含量升高后逐渐趋于稳定,总酚含量先降低后升高,总类黄酮含量及单粒重先升高后降低。2个小麦品种籽粒中各营养物质含量及单粒重的动态变化趋势相似,但各营养物质含量的高低及其差异显著性却各有不同。不同阶段的单粒重与对应阶段营养物质的含量存在不同程度的相关性,即使是同一种营养物质,在籽粒发育的不同阶段与单粒重的相关性也不尽相同。 展开更多
关键词 小麦 籽粒 营养物质 动态
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面向无人艇自主靠泊的分层轨迹规划与试验 预览
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作者 李晔 贾知浩 +1 位作者 张伟斌 廖煜雷 《哈尔滨工程大学学报》 EI CAS CSCD 北大核心 2019年第6期1043-1050,共8页
针对小型无人艇在自主靠泊时的轨迹规划任务,分别考虑远端和码头末端2阶段的主要影响因素,本文提出基于环境障碍、泊位及艇体动力学等多约束分析的分层人工势场轨迹规划方法,完成面向无人艇自主靠泊的轨迹规划任务。考虑小型无人艇自身... 针对小型无人艇在自主靠泊时的轨迹规划任务,分别考虑远端和码头末端2阶段的主要影响因素,本文提出基于环境障碍、泊位及艇体动力学等多约束分析的分层人工势场轨迹规划方法,完成面向无人艇自主靠泊的轨迹规划任务。考虑小型无人艇自身体型较小、在低速靠泊状态下机动性较差、水域受限等导致的自主靠泊难题,提出基于靠泊约束分析的改进人工势场法,解决传统人工势场法中存在的弯角过大、艏向输出振荡和局部极小点问题。同时,考虑靠泊后期目标泊位及水域受限因素对无人艇艏向、速度的约束,使无人艇能够沿规划轨迹自主安全地完成靠泊任务。通过与传统人工势场法的仿真结果对比,验证该方法具有更好的轨迹规划性能;并基于“海豚-Ⅰ”号小型无人艇完成自主靠泊外场试验,检验所提出方法的有效性和可行性。 展开更多
关键词 无人艇 动力学 约束分析 分层规划 轨迹规划 人工势场 受限水域 靠泊
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双臂机器人动力学建模与伺服系统控制 预览
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作者 刘江文 徐敏 《机械设计与制造》 北大核心 2019年第11期256-260,共5页
针对双臂机器人的手臂运动控制问题,研究了其动力学建模与伺服系统控制算法。首先,对其双臂机械结构进行了分析,总结了各个关节对机器人末端位姿的影响,并且简化了动力学方程更利于实现。其次针对简化后的模型参数采用最小二乘法辨识,... 针对双臂机器人的手臂运动控制问题,研究了其动力学建模与伺服系统控制算法。首先,对其双臂机械结构进行了分析,总结了各个关节对机器人末端位姿的影响,并且简化了动力学方程更利于实现。其次针对简化后的模型参数采用最小二乘法辨识,最后通过仿真和系统实验,验证动力学计算结果的正确性。再次由机器人动力学和电机动力学建立关节转矩模型进行关节转矩力控制;最后讨论了交流永磁同步电机的建模和控制问题。经过验证简化后的模型一方面等效于直流电机便于设计控制器,另一方面可用于机器人关节转矩控制。 展开更多
关键词 双臂机器人 动力学 伺服系统 电机控制
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虚拟样机技术在轴向柱塞泵仿真分析中的应用 预览
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作者 张鑫杰 谌炎辉 周知进 《机床与液压》 北大核心 2019年第9期144-148,共5页
固液耦合效果对柱塞泵运动学与动力学特性影响很大。利用有限元分析软件,建立柱塞泵刚柔耦合模型,在此基础上建立其固液耦合虚拟样机模型。仿真研究斜盘倾角、主轴转速对柱塞泵运动学和动力学特性的影响,以及柱塞腔内压力变化规律。结... 固液耦合效果对柱塞泵运动学与动力学特性影响很大。利用有限元分析软件,建立柱塞泵刚柔耦合模型,在此基础上建立其固液耦合虚拟样机模型。仿真研究斜盘倾角、主轴转速对柱塞泵运动学和动力学特性的影响,以及柱塞腔内压力变化规律。结果表明:泵的出口流量及压力脉动幅值随斜盘倾角的增大而增大;柱塞加速度与主轴转速的平方呈正比,造成柱塞泵受到的液压冲击力急剧增大。研究结果为柱塞泵性能的深入分析提供了参考。 展开更多
关键词 虚拟样机 轴向柱塞泵 柱塞 运动学 动力学
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基于SolidWorks Simulation的水泵动力学分析 预览
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作者 薛晓珍 《机械管理开发》 2019年第7期68-70,100共4页
对于某型高压大流量水泵项目的最终设计校核工作,利用SolidWorks搭建模水泵模型。模拟实际工况为模型添加约束及载荷,通过Motion插件对水泵进行了运动特性分析,然后将主要受力部件如滑块、连杆、曲轴的Motion仿真结果输入到Simulation中... 对于某型高压大流量水泵项目的最终设计校核工作,利用SolidWorks搭建模水泵模型。模拟实际工况为模型添加约束及载荷,通过Motion插件对水泵进行了运动特性分析,然后将主要受力部件如滑块、连杆、曲轴的Motion仿真结果输入到Simulation中,选取一个周期的算例进行有限元动力特性分析,得到水泵工作时主要受力零部件的实际工作情况下的运行、受力以及变形情况,校核了材料的可靠性。通过本次仿真可以直观地看到水泵各零部件的运动情况及受力情况,为该水泵的最终试制提供可靠的依据。 展开更多
关键词 水泵 MOTION SIMULATION 动力学 校核
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Ionization behavior and dynamics of picosecond laser filamentation in sapphire 预览
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作者 Amina Lingfei Ji +1 位作者 Tianyang Yan Rui Ma 《光电进展(英文)》 2019年第8期9-15,共7页
Currently,laser-induced structural modifications in optical materials have been an active field of research.In this paper,we reported structural modifications in the bulk of sapphire due to picosecond(ps)laser filamen... Currently,laser-induced structural modifications in optical materials have been an active field of research.In this paper,we reported structural modifications in the bulk of sapphire due to picosecond(ps)laser filamentation and analyzed the ionization dynamics of the filamentation.Numerical simulations uncovered that the high-intensity ps laser pulses generate plasma through multi-photon and avalanche ionizations that leads to the creation of two distinct types of structural changes in the material.The experimental bulk modifications consist of a void like structures surrounded by cracks which are followed by a submicrometer filamentary track.By increasing laser energy,the length of the damage and filamentary track appeared to increase.In addition,the transverse diameter of the damage zone increased due to the electron plasma produced by avalanche ionizations,but no increase in the filamentary zone diameter was observed with increasing laser energy. 展开更多
关键词 structural modifications SAPPHIRE picosecond laser FILAMENTATION ionization dynamics
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Molecular simulation of the interaction mechanism between CodY protein and DNA in Lactococcus lactis
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作者 Linchen Yuan Hao Wu +2 位作者 Yue Zhao Xiaoyu Qin Yanni Li 《化学科学与工程前沿:英文版》 EI CAS CSCD 2019年第1期133-139,共7页
In Lactococcus lactis, the global transcriptional regulatory factor CodY can interact with the promoter DNA to regulate the growth, metabolism, environmental adaptation and other biological activities of the strains. ... In Lactococcus lactis, the global transcriptional regulatory factor CodY can interact with the promoter DNA to regulate the growth, metabolism, environmental adaptation and other biological activities of the strains. In order to study the mechanism of interaction between CodY and its target DNA, molecular docking and molecular dynamics simulations were used to explore the binding process at molecular level. Through the calculations of the free energy of binding, hydrogen bonding and energy decomposition, nine key residues of CodY were identified, corresponding to SERI84, SERI 86, SER20& THR217, ARG21 & SER219, ASN223, LYS242 and GLY243, among which SERI86, ARG218 and LYS242 play a vital role in DNA binding. Our research results provide important theoretical guidance for using wet-lab methods to study and optimize the metabolic network regulated by CodY. 展开更多
关键词 CodY DNA MOLECULAR DOCKING MOLECULAR DYNAMICS
Media effects on the dynamics of a stochastic SIRI epidemic model with relapse and Lévy noise perturbation
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作者 Badr-Eddine Berrhazi Mohamed El Fatini +1 位作者 Roger Pettersson Aziz Laaribi 《生物数学学报:英文版》 2019年第3期227-247,共21页
In this paper, we study the dynamic properties of an SIRI epidemic model incorporating media coverage, and stochastically perturbed by a Lévy noise. We establish the existence of a unique global positive solution... In this paper, we study the dynamic properties of an SIRI epidemic model incorporating media coverage, and stochastically perturbed by a Lévy noise. We establish the existence of a unique global positive solution. We investigate the dynamic properties of the solution around both disease-free and endemic equilibria points of the deterministic model depending on the basic reproduction number under some noise excitation. Furthermore, we present some numerical simulations to support the theoretical results. 展开更多
关键词 DYNAMICS Lévy process white noisere LAPSE media COVERAGE
Multi-scale Simulation on Bonding Mechanism of Solid-Liquid Cast-Rolling of Cu/Al Cladding Strip based on FEM and MD
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作者 燕猛 黄华贵 +2 位作者 WANG Min YE Lifen SUN Jingna 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第4期830-839,共10页
To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, ... To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, with birth and death element method, a thermo-mechanical coupled finite element model(FEM) was set up to explore the temperature and contact pressure distribution at the Cu/Al bonding interface in the SLCRB process. Taking these macro-scale simulation results as boundary conditions, we simulated the atom diffusion law of the bonding interface by molecular dynamics(MD) in micro-scale. The results indicate that the temperature in Cu/Al bonding interface deceases from 700 to 320 ℃ from the entrance to the exit of caster, and the peak of contact pressure reaches up to 140 MPa. The interfacial diffusion thickness depends on temperature and rolling reduction, higher temperature results in larger thickness, and the rolling reduction below kiss point leads to significant elongation deformation of cladding strip which yields more newborn interface with fresh metal and make the diffusion layer thinner. The surface roughness of Cu strip was found to be benefit to atoms diffusion in the Cu/Al bonding interface. Meanwhile, combined with the SEM-EDS observation on the microstructure and composition in the bonding interface of the experimental samples acquired from the castrolling bite, it is revealed that the rolling reduction and severe elongation deformation in the solid-solid contact zone below kiss point guarantee the satisfactory metallurgical bonding with thin and smooth diffusion layer. The bonding mechanisms of reactive diffusion, mechanical interlocking and crack bonding are proved to coexist in the SLCRB process. 展开更多
关键词 CU/AL cladding strip SOLID-LIQUID cast-roll BONDING (SLCRB) BONDING MECHANISM finite element method (FEM) molecular dynamics (MD)
多维磁悬浮隔振系统动力学模型与控制策略
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作者 武倩倩 崔宁 +2 位作者 刘碧龙 岳洪浩 刘荣强 《航空学报》 EI CAS CSCD 北大核心 2019年第6期153-163,共11页
磁悬浮隔振系统具有非线性、强耦合、高响应、宽频带等特点,系统的隔振控制目标与其定子和浮子之间的位置约束相互制约,这对系统的精密控制提出了较大的挑战。为解决该问题,建立了面向控制的六自由度磁悬浮隔振系统非线性动力学模型,并... 磁悬浮隔振系统具有非线性、强耦合、高响应、宽频带等特点,系统的隔振控制目标与其定子和浮子之间的位置约束相互制约,这对系统的精密控制提出了较大的挑战。为解决该问题,建立了面向控制的六自由度磁悬浮隔振系统非线性动力学模型,并提出了双闭环控制策略,使系统在低频到中高频带内实现隔振控制,在极低频带内实现跟踪控制。采用PD定点控制算法,在MATLAB/Simulink环境中开发了控制系统仿真程序,通过分析不同扰动频率下浮子的绝对运动响应以及定子与浮子之间的相对运动响应,获得了系统的隔振控制与跟踪控制仿真结果。搭建了磁悬浮隔振平台样机测试系统,验证了动力学模型的正确性和控制策略的有效性。 展开更多
关键词 磁悬浮 隔振 动力学 控制策略 PD定点控制
Three-Dimensional Growth of Coherent Ferrite in Austenite:A Molecular Dynamics Study
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作者 Zhi-Peng Sun Fu-Zhi Dai +1 位作者 Ben Xu Wen-Zheng Zhang 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第6期669-676,共8页
Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases.As a key feature of microstructure,the morphology of the coherent particles... Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases.As a key feature of microstructure,the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys.This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation.We found that the ferrite grain tends to grow into an elongated plate-like shape,independent of its initial confi guration.The fi nal shape of the ferrite is closely related to the misfi t between the two phases,with the longest direction and the broad facet of the plate being,respectively,consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC)method.The strain energy calculation in the framework of Eshelby’s inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable.It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems. 展开更多
关键词 COHERENT FERRITE Anisotropic GROWTH Molecular dynamics simulation BURGERS vector content Eshelby’s inclusion theory
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