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Complex Wave Excitations in Generalized Broer-Kaup System

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Communications in Theoretical Physics 2007年第4X期48卷 657-661页

作者： ZHENG chun-Long FEI Jin-xi College of Mathematics and Physics Lishui University Lishui 323000 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

Starting from an improved projective method and a linear variable separation approach, new families of variable separation solutions （including solltary wave solutlons, periodic wave solutions and rational function solutions） with arbitrary functions [or the （2＋ 1）-dimensional general/zed Broer-Kaup （GBK） system are derived. Usually, in terms of solitary wave solutions and/or rational function solutions, one can find abundant important localized excitations. However, based on the derived periodic wave solution in this paper, we reveal some complex wave excitations in the （2＋1）-dimensional GBK system, which describe solitons moving on a periodic wave background. Some interesting evolutional properties for these solitary waves propagating on the periodic wave bactground are also briefly discussed.

关键词： improved projective method GBK system exact solution complex wave excitation

Toolpath Interpolation and Smoothing for Computer Numerical Control Machining of Freeform Surfaces: A Review

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International Journal of Automation and computing 2020年第1期17卷 1-16页

作者： Wen-Bin Zhong xi-chun Luo Wen-Long Chang Yu-Kui Cai Fei Ding hai-Tao Liu Ya-Zhou Sun Centre for Precision Manufacturing Department of DesignManufacture&Engineering Management(DMEM)University of StrathclydeGlasgow G11XJUK Engineering and Physical Sciences Research Council(EPSRC)Future Metrology Hub Centre for Precision TechnologiesUniversity of HuddersfieldHuddersfield HD13DHUK School of Mechatronic Engineering Harbin Institute of TechnologyHarbin 150001China

Driven by the ever increasing demand in function integration,more and more next generation high value-added products,such as head-up displays,solar concentrators and intra-ocular-lens,etc.,are designed to possess freeform(i.e.,non-rotational symmetric)*** toolpath,composed of high density of short linear and circular segments,is generally used in computer numerical control(CNC)systems to machine those ***,the discontinuity between toolpath segments leads to high-frequency fluctuation of feedrate and acceleration,which will decrease the machining efficiency and product surface *** by the ever-increasing need for high-speed high-precision machining of those products,many novel toolpath interpolation and smoothing approaches have been proposed in both academia and industry,aiming to alleviate the issues caused by the conventional toolpath representation and interpolation *** paper provides a comprehensive review of the state-of-the-art toolpath interpolation and smoothing approaches with systematic *** advantages and disadvantages of these approaches are *** future research directions are also offered.

关键词： Computer numerical control(CNC) toolpath interpolation smoothing freeform surface

Quantum Heat Engine and Negative Boltzmann Temperature

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Communications in Theoretical Physics 2017年第9期67卷 347-356页

作者： Jing-Yi xi hai-Tao Quan Academy for Advanced Interdisciplinary Studies Peking University Beijing 100871 China School of Physics Peking University Beijing 100871 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China

To clarify the ambiguity on negative Boltzmann temperature in literature, we study the Carnot and the Otto cycle with one of the heat reservoirs at the negative Boltzmann temperature based on a canonical ensemble description. The work extraction, entropy production and the efficiency of these cycles are explored. Conditions for constructing and properties of these thermodynamic cycles are elucidated. We find that the apparent "violation" of the second law of thermodynamics in these cycles are due to the fact that the traditional definition of thermodynamic efficiency is inappropriate in this situation. When properly understanding the efficiency and the adiabatic processes, in which the system crosses over "absolute ZERO" in a limit sense, the Carnot cycle with one of the heat reservoirs at a negative Boltzmann temperature can be understood straightforwardly, and it contradicts neither the second nor the third law of thermodynamics. Hence, negative Boltzmann temperature is a consistent concept in thermodynamics. We use a two-level system and an Ising spin system to illustrate our central results.

关键词： quantum heat engines negative Boltzman temperature thermodynamics laws

Quasi-static-dynamic formability of AA5052-O sheet under uniaxial and plane-strain tension

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Transactions of Nonferrous Metals Society of China 2009年第S02期19卷 318-325页

作者： LIU Da-hai YU hai-ping LI chun-feng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

An experimental study on the quasi-static-dynamic formability specified in electromagnetically assisted sheet metal stamping(EMAS)was presented.A series of uniaxial and plane-strain tensile experiments were carried out on AA5052-O sheet by using a combined quasi-static stretching and pulsed electromagnetic forming(EMF)*** strains representing formability beyond conventional quasi-static forming limits are observed under both uniaxial tensile and plane-strain *** total forming limits of the as-received aluminum alloy undergoing both low and high quasi-static pre-straining are almost similar in quasi-static-dynamic *** total formability seems to depend largely on the high-velocity loading ***, it appears that for quasi-static-dynamic deformation,the quasi-static pre-straining of material is not of primary importance to the additionally useful *** observations will enable to develop forming operations that take advantage of this improvement in formability,and will also enable the use of a quasi-static preform fairly close to the quasi-static forming limits without weakening its total formability for design of an EMAS process in shaping large aluminum shell parts like auto body panels.

关键词： electromagnetically assisted sheet metal stamping(EMAS) aluminum alloy sheet electromagnetic forming(EMF) quasi-static-dynamic deformation

Effects of temperature and discharge parameters on ozone concentration of negative corona discharge

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Journal of Environmental Sciences 2003年第6期15卷 796-799页

作者： WANG hai-jun SHENG Lian-xi XU De-xuan Department of Environmental Science and Engineering College of Urban and Environmental ScienceNortheast Normal UniversityChangchun 130024China.

The relationship of the ozone generation and the heating power, corona wire surface temperature, discharge electrode and netting electrode was studied during the negative corona discharge. The experimental results showed that the ozone concentration reduced with applied voltage decrease. With heating power increase, the ozone concentration of unit current decreased at exponential rate and it almost change no longer over 0.40 W. Under given temperature, the lower the applied voltage was, the smaller the ozone concentration was; while under given applied voltages, only over 11 kV could decrease with the surface temperature increase. The ozone concentration decreased with the lengthening of corona wire, and could reduced to 10 ppb under experimental condition of 14.2 kV; it also decreased with the shortening of wire diameter, and could decrease 67% at best in the given condition. Moreover, it decreased with the increasing size of netting electrode mesh. At the anion current of 1.65 μΑ, the ozone concentration of 5.0×5.0 cm 2 is only 41% of that of 3.3×3.3 cm 2.

关键词： ozone negative corona discharge anion current

Key machining characteristics in ultrasonic vibration cutting of single crystal silicon for micro grooves

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Advances in Manufacturing 2019年第3期7卷 303-314页

作者： Jun-Yun Chen Tian-Ye Jin xi-chun Luo College of Vehicles and Energy Yanshan UniversityQinhuangdao 066004HebeiPeople's Republic of China Department of Design Manufacture and Engineering ManagementFaculty of EngineeringUniversity of StrathclydeGlasgow G11XJUK Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001People's Republic of China

Structured complex silicon components have been widely used in solar cells,biomedical engineering and other industrial *** silicon is a typical brittle material,ultrasonic vibration cutting(UVC)is a promising method to achieve better cutting performance than conventional ***-frequency ID UVC possesses higher nominal cutting speed and material removal rate than many 2D/3D UVC systems,and thus,it has great development potential in industrial applications of structured silicon ***,few researchers have applied ID UVC to the cutting of structured silicon surfaces,since its main drawback is tool marks imprinted by the vibration on machined *** this study,to uncover the key machining characteristics under the condition of ID UVC,a series of tests involving diamond cutting grooves were first performed on the silicon *** machined surface and chips were subsequently measured and analyzed to evaluate the critical undeformed chip thickness,surface characteristics,and chip *** the main drawback of ID UVC,a novel theoretical model was developed for predicting the length of tool marks and evaluating the impact of tool marks on the surface *** results demonstrated that the critical undeformed chip thickness of silicon reached 1030 nm under a certain vibration amplitude and that an array of micro grooves was generated at the plastic region with a surface roughness(7?a)as low as 1.11 ***,the micro topography of the continuous chips exhibited discontinuous clusters of lines with diameters of dozens of nanometers,only composed of *** novel theoretical model was able to predict the length of tool marks with low ***,the impact of tool marks on the surface finish can be reduced and even eliminated with help of the model.

关键词： Ultrasonic vibration cutting(UVC) Single crystal Silicon Micro groove Chip Tool vibration mark

Hot Deformation Behavior and Processing Map of a Cu-Bearing 2205 Duplex Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2019年第12期32卷 1537-1548页

作者： Tong xi Lu Yin chun-Guang Yang Ke Yang Institute of Metal Research Chinese Academy of Sciences

The hot deformation behavior and processing map of Cu-bearing 2205 duplex stainless steel(2205-Cu DSS)were investigated at temperatures of 950-1150℃ and strain rates of 0.01-10 s^-*** effects of Cu addition and different deformation parameters on deformation behavior were,respectively,characterized by analyzing flow curves,constitutive equations and *** results indicated that the shapes of flow curves strongly depended on the volume fraction of two *** deformed at low strain rate,DRV in ferrite was prompted with increase in the temperature and was further developed to continuous *** high strain rate,flow localization preferentially occurred in ferrite at low deformation temperature due to the strain partitioning and relatively less fraction of *** activation energy for 2205-Cu DSS was 452 kJ/mol and was found to connect with the variation of strain,strain rate and deformation *** optimum hot deformation parameters for 2205-Cu DSS were obtained in the temperature range of 1100-1150℃ and strain rate range of 0.1-1 s^-1 with a peak power dissipation efficiency of 41%.Flow localization was the main way to lead to flow ***,the Cu-rich precipitates were generated within a few ferrite grains when deformed at temperature lower than 1000℃.The interaction between dislocations and Cu-rich precipitates at high strain rate,as well as the limited DRV in ferrite and DRX in austenite,contributed to the complex microstructure and flow behavior.

关键词： Cu-bearing duplex stainless steel Hot deformation Processing map Dynamic recrystallization Dynamic recovery

Recursive calibration for a lithium iron phosphate battery for electric vehicles using extended Kalman filtering

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第11期12卷 818-825页

作者： xiao-song HU Feng-chun SUN xi-ming CHENG National Engineering Laboratory for Electric Vehicles Department of Mechanical EngineeringBeijing Institute of Technology Beijing 100081 China

In this paper,an efficient model structure composed of a second-order resistance-capacitance network and a simply analytical open circuit voltage versus state of charge(SOC) map is applied to characterize the voltage behavior of a lithium iron phosphate battery for electric vehicles(EVs).As a result,the overpotentials of the battery can be depicted using a second-order circuit network and the model parameterization can be realized under any battery loading profile,without a special characterization *** order to ensure good robustness,extended Kalman filtering is adopted to recursively implement the calibration *** linearization involved in the calibration algorithm is realized through recurrent derivatives in a recursive *** results show that the recursively calibrated battery model can accurately delineate the battery voltage behavior under two different transient power operating conditions.A comparison with a first-order model indicates that the recursively calibrated second-order model has a comparable accuracy in a major part of the battery SOC range and a better performance when the SOC is relatively low.

关键词： Model calibration Lithium iron phosphate battery Electric vehicle (EV) Extended Kalman filtering

Dynamical analysis and performance evaluation of a biped robot under multi-source random disturbances

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Acta Mechanica Sinica 2014年第6期30卷 983-994页

作者： chun-Biao Gan Chang-Tao Ding Shi-xi Yang The State Key Laboratory of Fluid Power Transmission and Control Department of Mechanical EngineeringZhejiang University

During bipedal walking,it is critical to detect and adjust the robot postures by feedback control to maintain its normal state amidst multi-source random disturbances arising from some unavoidable uncertain *** radical basis function（RBF）neural network model of a five-link biped robot is established,and two certain disturbances and a randomly uncertain disturbance are then mixed with the optimal torques in the network model to study the performance of the biped robot by several evaluation indices and a specific Poincar′e *** contrast with the simulations,the response varies as desired under optimal inputting while the output is fluctuating in the situation of disturbance *** results from noise inputting also show that the dynamics of the robot is less sensitive to the disturbance of knee joint input of the swing leg than those of the other three joints,the response errors of the biped will be increasing with higher disturbance levels,and especially there are larger output fluctuations in the knee and hip joints of the swing leg.

关键词： Biped robot Multi-source random disturbances Sensitive parameters RBF neural network Taguchi method Performance evaluation