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针对高速车辆线性稳定性的等效锥度运用限值确定方法
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作者 孙建锋 郝光 +1 位作者 池茂儒 施继忠 《中国铁道科学》 EI CAS CSCD 北大核心 2024年第5期168-178,共11页
为制定合理的轮轨匹配等效锥度运用范围,避免高速车辆出现蛇行失稳现象,提出一种基于模态分析的轮轨匹配等效锥度合理运用限值确定方法。首先,基于车辆系统动力学理论,建立包含21个自由度的高速车辆系统横向动力学模型;其次,采用模态分... 为制定合理的轮轨匹配等效锥度运用范围,避免高速车辆出现蛇行失稳现象,提出一种基于模态分析的轮轨匹配等效锥度合理运用限值确定方法。首先,基于车辆系统动力学理论,建立包含21个自由度的高速车辆系统横向动力学模型;其次,采用模态分析计算车辆系统模态参数(模态频率、阻尼比和振型),并提出基于最小模态距离的蛇行频率连续跟踪算法;然后,利用车辆系统模态最小阻尼比判断模态振型,对轮轨匹配等效锥度和速度进行协同变参计算,确定等效锥度运用限值;最后,从模态视角研究车体蛇行失稳的发生机制。结果表明:在广域轮轨匹配关系下,转向架蛇行失稳和车体蛇行失稳区域均具有清晰的边界,且二者不邻接;对于车体蛇行失稳而言,频率耦合不是唯一决定因素,频率耦合速度也是决定因素之一,当频率耦合发生在较高速度下时易发生车体蛇行失稳。采用该方法,确定所构建的高速车辆模型在350 km·h^(-1)车速下的等效锥度运用限值为0.07~0.41。 展开更多
关键词 蛇行稳定性 高速车辆 等效锥度运用 模态分析 机理分析
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基于动车组横向稳定性的等效锥度限值研究 被引量:13
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作者 许自强 《中国铁路》 2017年第12期29-34,共6页
轮轨接触几何匹配关系直接影响动车组的振动性能,轮轨接触不匹配可造成动车组构架横向加速度报警、车体晃车等问题。通过对镟修后初始等效锥度和车体晃车进行研究,提出镟修后初始等效锥度限值,评价镟修质量。通过对服役动车组等效锥度... 轮轨接触几何匹配关系直接影响动车组的振动性能,轮轨接触不匹配可造成动车组构架横向加速度报警、车体晃车等问题。通过对镟修后初始等效锥度和车体晃车进行研究,提出镟修后初始等效锥度限值,评价镟修质量。通过对服役动车组等效锥度的跟踪、镟修到限等效锥度分布范围与报警轮对等效锥度值的统计,提出LMA、LMB、LMC、LMD型4种车轮踏面不同速度级的服役等效锥度限值,评估动车组横向稳定性。根据等效锥度限值对车轮进行管理可以控制轮轨型面与接触关系,有效缓解构架横向加速度报警与车体晃车问题,实现车轮状态修,提高镟修经济性。 展开更多
关键词 横向稳定性 车体晃车 等效锥度 LMB型车轮踏面 轮轨接触
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常见窄治疗指数药物及其生物等效性评价现状 被引量:7
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作者 陈小平 胡朝英 张兰 《中国临床药理学与治疗学》 CAS CSCD 2019年第10期1188-1193,共6页
目前我国窄治疗指数药物的生物等效性评价仍存在一定盲区,尚未发布相关的指导原则。国际上主要药品监管机构对窄治疗指数药物的生物等效性研究要求各不相同,而且也没有全球统一的窄治疗指数药物目录,并且不同的地区对于相同的窄治疗指... 目前我国窄治疗指数药物的生物等效性评价仍存在一定盲区,尚未发布相关的指导原则。国际上主要药品监管机构对窄治疗指数药物的生物等效性研究要求各不相同,而且也没有全球统一的窄治疗指数药物目录,并且不同的地区对于相同的窄治疗指数药物其生物等效限要求也不同。本文参考国内外法规、指导原则及相关文献,分析和介绍了几种主要的窄治疗指数类药物及生物等效性研究的现状,希望能够对我国窄治疗指数药物生物等效性试验的开展和指导原则的制定有所帮助。 展开更多
关键词 窄治疗指数药物 生物等效性试验 等效限
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FEM modeling of softened base metal in narrow-gap joint by CMT+P MIX welding procedure 被引量:2
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作者 舒凤远 吕耀辉 +4 位作者 刘玉欣 徐富家 孙哲 何鹏 徐滨士 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第6期1830-1835,共6页
A required finite element method(FEM) model applicable for narrow gap CMT and CMT+P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire f... A required finite element method(FEM) model applicable for narrow gap CMT and CMT+P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire feeding pulses and heat input pulses was supposed under the conduction of equivalent input.The method together with composed double-ellipse heat sources was included in the model.The model was employed in the investigation of thermal cycling and the identification of the softened zone of AA7A52 base plates.Low-frequency behavior emerged in the form of low-cooling rate sects,which were not expected under experimental conditions.The softened zone including the quenched zone and averaging zone of the base plate was much wider internal the base plate than that close to the surfaces.The reliability of the predictions in thermal cycling was supported by infrared imaging test results of the thermal cycle process. 展开更多
关键词 cold metal transferring finite element method equivalent input low-cooling rate sects softened zone
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Calculation of effective temperature for pavement rutting using numerical simulation methods 被引量:2
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作者 祝谭雍 马涛 黄晓明 《Journal of Southeast University(English Edition)》 EI CAS 2016年第3期362-367,共6页
In order to predict the long-term rutting of asphalt pavement, the effective temperature for pavement rutting is calculated using the numerical simulation method. The transient temperature field of asphalt pavement wa... In order to predict the long-term rutting of asphalt pavement, the effective temperature for pavement rutting is calculated using the numerical simulation method. The transient temperature field of asphalt pavement was simulated based on actual meteorological data of Nanjing. 24-hour rutting development under a transient temperature field was calculated in each month. The rutting depth accumulated under the static temperature field was also estimated and the relationship between constant temperature parameters was analyzed. Then the effective temperature for pavement rutting was determined based on the rutting equivalence principle. The results show that the monthly effective temperature is above 40 t in July and August, while in June and September it ranges from 30 to 40 Rutting development can be ignored when the monthly effective temperature is less than 30 t. The yearly effective temperature for rutting in Nanjing is around 38. 5 t. The long-term rutting prediction model based on the effective temperature can reflect the influences of meteorological factors and traffic time distribution. 展开更多
关键词 transient temperature field long-term rutting effective temperature numerical simulation finite element method
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EVALUATION OF ELECTROMAGNETIC SCATTERING OF TWO DIMENSIONAL CONDUCTING OBJECTS--TE CASE 被引量:1
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作者 丁卫平 徐金平 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2001年第2期213-218,共6页
A hybrid technique is developed for the evaluation of two dimensional electromagnetic scattering from electrically large conducting bodies with cracks on their surfaces (TE case). The edge based finite element metho... A hybrid technique is developed for the evaluation of two dimensional electromagnetic scattering from electrically large conducting bodies with cracks on their surfaces (TE case). The edge based finite element method (FEM) is employed to compute the scattering from the cracks. Physical optics (PO) and physical theory of diffraction (PTD) are utilized to evaluate the scattering from the large bodies with the cracks filled with perfect conductors. These two methods are combined by an efficient coupling scheme. Some of numerical results are presented. It is shown that the hybrid technique has some advantages over other methods in regard to saving computer memory units and CPU time. 展开更多
关键词 electromagnetic scattering physical optics physical theory of diffraction edge based FEM equivalence theorem
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高层剪力墙底部加强部位最小厚度取值的商榷
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作者 张伟 梁兴文 《建筑结构》 CSCD 北大核心 2007年第12期10-13,共4页
高层剪力墙结构底部加强部位墙厚若要满足《高层建筑混凝土结构技术规程》(JGJ3—2002)第7.2.2-1-3款要求,可能会较大,不经济。按附录D墙体稳定计算方法,虽然为规程所允许,但该法在实际设计中运用不方便。引入满足稳定要求的等效轴压... 高层剪力墙结构底部加强部位墙厚若要满足《高层建筑混凝土结构技术规程》(JGJ3—2002)第7.2.2-1-3款要求,可能会较大,不经济。按附录D墙体稳定计算方法,虽然为规程所允许,但该法在实际设计中运用不方便。引入满足稳定要求的等效轴压比限值[neq],以此来判断墙体是否满足稳定性要求。基于该等效轴压比限值的概念,分析三种常见截面墙体厚度在不满足最小厚度规定时的可行范围。建议对不满足最小墙厚规定的剪力墙结构,可以采用该等效轴压比和规程第7.2.14条给出的轴压比限值进行双重控制来确定其厚度取值。 展开更多
关键词 剪力墙结构 稳定性能 等效轴压比 计算长度系数
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Influence of longitudinal slope on the mechanical response of steel deck pavement 被引量:3
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作者 Chen Xiaobing  Xu Libin +1 位作者 Luo Ruilin Liu Han 《Journal of Southeast University(English Edition)》 EI CAS 2018年第1期71-77,共7页
In order to study the influence of longitudinal slope on the mechanical response of steel deck pavement,a method of slope-modulus transformation was proposed for the mechanical analysis of the steel deck pavement base... In order to study the influence of longitudinal slope on the mechanical response of steel deck pavement,a method of slope-modulus transformation was proposed for the mechanical analysis of the steel deck pavement based on the time-temperature equivalence principle.Considering the mechanical action on a slope,a finite element model of the deck pavement was established to determine the critical load position of tensileand shear stress of the steel deck pavement.Additionally,the influence of longitudinal slope on the mechanical response of the deck pavement under the conditions of uniform speed and emergency braking was analyzed.The results indicate that the maximum transverse tensile stress at the pavement surface and the maximum transverse shear stress at the pavement bottom are always greater than their longitudinal counterparts under uniform speed.Under emergency braking,however,the critical slope gradient of t e maximum transverse and longitudinal tensile stress at t e pavement surface is 6%.The maximum longitudinal shear stess at t e pavement bottom is always greater ta n t e maximum tansverse shear stess.This stidy is helpful in t e strctural design of large longitudinal slope steel deck pavements. 展开更多
关键词 longitudinal slope steel deck pavement STRESS critical load position time-temperature equivalence finite element method
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Optimal design of structural parameters for shield cutterhead based on fuzzy mathematics and multi-objective genetic algorithm 被引量:12
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作者 夏毅敏 唐露 +2 位作者 暨智勇 程永亮 卞章括 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期937-945,共9页
In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters ... In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%. 展开更多
关键词 shield tunneling machine cutterhead structural parameters fuzzy mathematics finite element optimization
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Analysis of strain variation in cross shear zone of plate during snake hot rolling 被引量:1
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作者 张涛 吴运新 +2 位作者 龚海 石文泽 蒋方敏 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第2期296-302,共7页
In order to study the distribution of equivalent and shear strain of aluminum alloy plate during snake hot rolling, several coupled thermo-mechanical finite element models(FEM) are established. Effects of speed ratio ... In order to study the distribution of equivalent and shear strain of aluminum alloy plate during snake hot rolling, several coupled thermo-mechanical finite element models(FEM) are established. Effects of speed ratio and offset distance on strain distribution of the plate are analyzed. The length of cross shear zone is defined to have a better understanding of the deformation characteristic in cross shear zone, which is the essential difference from symmetrical rolling in deformation zone. The results show that the equivalent strain and shear strain of lower part both increase with the increase of speed ratio, while the upper part decreases; the equivalent strain through the whole thickness decreases with ascending offset distance, while the shear strain of lower part increases. The length of cross shear zone quickly increases with ascending speed ratio and slightly decreases with ascending offset distance. The "positive" and "negative" cross shear zones are formed with the increase of speed ratio and offset distance, respectively. The value of the sensitivity coefficient of speed ratio is an order of magnitude bigger than the offset distance. However, the shear strain at center point increases with the ascending speed ratio and offset distance for different mechanism. As speed ratio increases, the asymmetry of the distribution of equivalent is becoming larger and the shear strain is generated in the same direction in cross shear zone. The FEM results agree well with experimental results. 展开更多
关键词 aluminum alloy plate snake hot rolling speed ratio offset distance cross shear zone
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An Efficient Approach for the Numerical Identification of R and L Parameters of High Frequency Multi-winding Transformers
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作者 Z. De Greve O. Deblecker J. Lobry 《Journal of Energy and Power Engineering》 2011年第7期641-650,共10页
In this paper, equivalent circuits for high frequency multi-winding magnetic components are derived from finite element (FE) computations. Lumped parameter models are first presented, based on previously published w... In this paper, equivalent circuits for high frequency multi-winding magnetic components are derived from finite element (FE) computations. Lumped parameter models are first presented, based on previously published work. All parameters of these circuits can be interpreted as the results of open and short-circuit tests on the transformer. Based on this consideration, numerical procedures are then proposed to derive frequency-dependent lumped parameters from FE simulations. By using an adequate formulation, parameters are directly obtained from the FE model degrees of freedom, without performing any volume integration in post-processing, which can be source of numerical errors. In this contribution, attention is paid on the modeling of magnetic coupling using inductances, and dissipative effects (winding and core losses) using resistances. The impact of conductor eddy currents on the circuit parameters is moreover studied in details. Instead of an analysis of the impact conductor eddy currents may have on the circuit parameters is moreover carried through. 展开更多
关键词 Multi-winding transformer finite elements lumped parameter circuits.
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Modelling of Transduction Heaters Using Transformer Equivalent Circuit and Finite Element Analysis
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作者 Lisiate Takau Pat Bodger 《Journal of Energy and Power Engineering》 2014年第6期1085-1092,共8页
This paper presents the modelling of transduction heaters using the TEC (transformer equivalent circuit) model and FEA (finite element analysis). Each model was used to simulate a set oftransduction heating experi... This paper presents the modelling of transduction heaters using the TEC (transformer equivalent circuit) model and FEA (finite element analysis). Each model was used to simulate a set oftransduction heating experiments and the results compared. Analysis of the TEC calculated results suggested modification of three parameters: the secondary resistance, the core tube eddy current resistance and the core tube magnetizing reactance. The improved TEC model was then used to design, build and test a 6 kW transduction heater. The measured results are compared with calculated results from the TEC and FEA models. The TEC model accurately predicts the performance of the heater. 展开更多
关键词 Induction heating transduction heating transformer equivalent circuit finite element analysis.
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Calculations of the bounds on limit cycle oscillations in nonlinear aeroelastic systems based on equivalent linearization 被引量:1
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作者 CHEN FeiXin LIU JiKe CHEN YanMao 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第6期1249-1256,共8页
The nonlinear aeroelastic system of an airfoil with an external store was investigated,with emphasis on the bounds of limit cycle oscillations(LCOs).Based on the equivalent linearization,an approach was proposed to ca... The nonlinear aeroelastic system of an airfoil with an external store was investigated,with emphasis on the bounds of limit cycle oscillations(LCOs).Based on the equivalent linearization,an approach was proposed to calculate the bounds on LCOs over the full flight envelope.The bounds are determined directly without solving LCOs one by one as the flow speed varies.The presented approach can provide us with the maximal LCO amplitudes and the lower threshold for flow speed beyond which LCOs may arise.Numerical examples show that the obtained bounds are in nice agreement with numerical simulation results.The speed threshold can be predicted to a relative error less than 0.1%,and the maximal LCO amplitude to about 3%.The influences of the system parameters on the speed threshold for speed were investigated efficiently by the proposed approach. 展开更多
关键词 nonlinear aeroelastic limit cycle oscillation BOUND equivalent linearization
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LIMIT BEHMIOUR OF SOLUTIONS TOEQUIVALUED SURFACE BOUNDAny VALUEPROBLEM FOR PARABOLIC EQUATIONS
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《Journal of Systems Science & Complexity》 SCIE EI CSCD 2002年第2期164-175,共12页
Abstract. In this paper, we discuss the limit behaviour of solutious to equivalued surfaceboundary value problem for parabolic equations when the equivalued surface boundaryshrinks to a point and the space dimension o... Abstract. In this paper, we discuss the limit behaviour of solutious to equivalued surfaceboundary value problem for parabolic equations when the equivalued surface boundaryshrinks to a point and the space dimension of the domain is two or more. 展开更多
关键词 Parabolic equation equivalued boundary value problem limit behaviour.
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Light-induced electro-rotation:Microspheres spin in micro-manipulation using light-induced dielectrophoresis 被引量:1
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作者 NI ZhongHua ZU ShuCun CHEN Ke 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第11期3035-3046,共12页
According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark reg... According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark regions on the photoconductive layer was demonstrated.Besides,the phenomenon of the light-induced electro-rotation(LIER) caused by the light-induced rotating electric field was confirmed numerically and experimentally for the first time.It may be helpful to go out of the dilemma that only the dipole moment model,based on the effect of light-induced partial potentials,can be used for LIDEP theoretical calculation currently.Through the FEM simulation and the electro-rotating experiment of yeast cells,it was found that the direction of yeast's LIER is relevant to the distance between its location and the edge of optical electrode,and the spin velocity of LIER is inversely proportional to that distance.Nevertheless,the LIER torques in the three-electrode mode show a non-uniform distribution where the LIDEP forces are harmful for a particle spinning stably around a fixed axis.Moreover,a four-electrode double-layer mode was proposed for the first time and the finite element simulation results agreed with the expected design,suggesting a new way for the dielectric spectrum measurement based on LIER. 展开更多
关键词 light-induced dielectrophoresis light-induced electro-rotation microfluidic device
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