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FORCE CHARACTERISTICS AND VORTEX SHEDDING OF A PITCHING FOIL IN SHEAR FLOWS

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Journal of Hydrodynamics 2005年第1期17卷 27-33页

作者： LIDan-yong LIUNan-sheng LUXi-yun YINXie-zhen DepartmentofMechanicsandMechanicalEngineering UniversityofScienceandTechnologyofChinaHefei230026China

The objective of this study is to deal with unsteady force acting on a pitching foil in shear flow and to study the relation of the force characteristics with vortex shedding near the foil. The two dimensional incompressible Navier Stokes equations in the vorticity and stream function formulation were solved with the fourth order essentially compact finite difference schemes for the space derivatives and a fourth order Runge Kutta scheme for the time advancement. The force characteristics and vortex shedding of the pitching foil in shear flows were investigated. The effects of some typical factors, including the incoming flow shear, the oscillating frequency and amplitude, on the vortex shedding and force behavior were analyzed and discussed.

关键词： vortex dynamics vortex shedding force unsteady flow locomotion biomechanics

Individual-tree diameter growth model for Korean pine plantations based on optimized interpolation of meteorological variables

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Journal of Forestry Research 2021年第4期32卷 1535-1552页

作者： Man Wang Yinghui zhao zhen zhen Xingji Jin School of Forestry Northeast Forestry UniversityHarbin 150040HeilongjiangPeople’s Republic of China Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education Northeast Forestry UniversityHarbin 150040HeilongjiangPeople’s Republic of China

To explore the influence of meteorological variables on the growth of Korean pine(Pinus koraiensis *** Zucc.) plantations and provide a scientific reference for the production and management of Korean pine,three approaches to interpolate meteorological variables during the growing season(i.e.,May-September) were compared in Heilongjiang Province,*** meteorological variable interpolation results were then combined with stand and individual tree variables,based on data from 56 sample plots and 2886 sample trees from Korean pine plantations in two regions of the province to develop an individualtree diameter growth model(Model I) and an individualtree diameter growth model with meteorological variables(Model Ⅱ) using a stepwise regression ***,an individual-tree diameter growth model with regional effects(Model Ⅲ) was developed using dummy variables in the regression,and the significance of introducing these dummy variables was verified with an F-test statistical *** models were validated using an independent data set,and the predictive performance of the three models was assessed via the adjusted coefficient of determination(R_(a)^(2)) and root mean square error(RMSE).The results suggest that the growth increment in tree diameter of Korean pine plantations was significantly correlated with the natural logarithm of initial diameter(ln D),stand basal area(BAS),logarithmic deformation of the stand density index(ln SDI),ratio of basal area of trees larger than the subject tree to their initial diameter at breast height(DBH)(BAL/D),and the maximum growingseason precipitation(Pgmax).The individual-tree diameter growth models of Korean pine plantations developed in this study will provide a good basis for estimating and predicting growth increments of Korean pine forests over larger areas.

关键词： Mixed interpolation Korean pine plantations Individual-tree diameter growth model Regional effects

Magneto-optic Crystal Polarization Controller Assisted Mode-Locked Fiber Laser

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Chinese Physics Letters 2011年第3期28卷 81-84页

作者： zhao Guang-zhen GUI Li-Li XIAO Xiao-sheng YANG Chang-Xi State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentsTsinghua UniversityBeijing 100084

We report a passively mode-locked erbium-doped fiber laser based on a compact magneto-optic crystal polarization *** length of the polarization controller consisting of four magneto-optic crystal rotators and two quarter wave-plates is only *** the polarization controller,central wavelength around 1559nm and repetition rate 21.10 MHz mode-locked pulse are *** duration and 3 dB spectrum width are 598.4fs and 6.24nm *** pulse energy is about *** of its small size,low insertion loss,good controllability and negligible dispersion,the magneto-optic crystal polarization controller could be an ideal polarization controller in fiber lasers.

关键词： polarization fiber passive

Theoretical Analysis of Rayleigh Backscattering Noise in Fiber Raman Amplifiers

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Communications in Theoretical Physics 2005年第5X期44卷 908-910页

作者： sheng zhao-Xia Department of Mathematics and Physical Science Tianjin University of Technology and Education Tianjin 300222 China

In this paper, a new theoretical model for Rayleigh backscattering (RB) analysis of fiber Raman amplifiers is proposed. The model includes all the interactions among the pumps, signals, and all orders of RB. The results show that the higher order RB has a negligible influence on the performance of the amplifier. The co-propagating and counterpropagating RB power of the signal grow quadratically with the net-gain of the amplifier. The signal to double Rayleigh backscattering noise ratio (OSNRDRB ) of backward-pumped FRAs is better than that of the forward-pumped ones at high net-gain level (＞ 13 dB), while at low net-gain level the OSNRDrb of the forward-pumped FRAs is slightly better than that of the backward-pumped ones.

关键词： fiber Raman amplifier Rayleigh scattering

Cationic potential:An effective descriptor for rational design of layered oxides for sodium-ion batteries

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Green Energy & Environment 2021年第4期6卷 455-457页

作者： Xudong zhao Li-zhen Fan zhen Zhou Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Key Laboratory for Advanced Energy Materials and TechnologiesUniversity of Science and Technology BeijingBeijing100083China Engineering Research Center of Advanced Functional Material Manufacturing of Ministry of Education School of Chemical EngineeringZhengzhou UniversityZhengzhou450001China

Sodium-ion batteries are very promising in large-scale energy *** exploration of Na layered oxides as cathode materials for Na ion batteries usually consumes much resource,while the performances of Na layered oxides are dominated by their crystal ***,it is highly desired to predict the stacking mode of the target oxides in advance:whether O3-type with higher ordered structure and stability,or P2-type with more Na *** this purpose density functional theory computations do not *** recently,Hu's group and international collaborators have proposed a cationic potential to provide a very timely,effective,and accurate criterion to predict the stacking mode of Na layered oxides(Science,370(2020)708-711).Under the guidance of the cationic potential phase map,Na layered oxides could be rationally *** we would like to highlight the progress that novel Na layered oxides could be obtained with the combination of large specific capacity,high power density and good cycling stability.

关键词： Na ion batteries Layered oxides Materials design

Design study of APS-U-type hybrid-MBA lattice for mid-energy DLSR

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Nuclear Science and Techniques 2021年第7期32卷 46-54页

作者： Yu zhao Yi Jiao sheng Wang Institute of High Energy Physics(IHEP) Chinese Academy of Sciences(CAS)Beijing 100049China University of Chinese Academy of Sciences(UCAS) Beijing 100049China Spallation Neutron Source Science Center(SNSSC) Dongguan 523803China

In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention *** have begun to design and build *** various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR *** on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with ***,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron *** linear and nonlinear dynamics are optimized to obtain a detailed design of this type of *** emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is *** horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ***,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.

关键词： Southern advanced photon source(SAPS) Diffraction-limited storage ring(DLSR) Hybrid multibend achromat(H-MBA) Advanced photon source upgrade project(APS-U) Lattice design

A novel phenomenological model using a sine function for finite-element simulation of large-strain hot deformation

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Science China(Technological Sciences) 2018年第5期61卷 748-760页

作者： ZENG Fan HU ChengLiang zhao zhen Institute of Forming Technology & Equipment Shanghai Jiao Tong University

In hot deformation, the flow stress curves of steels always present as two typical types: at relatively high temperature and low strain rate, the flow stress may first increase and then attain a steady value without reaching an obvious peak stress; in other situations, the flow stress decreases after reaching peak stress and then attains a steady value. A new phenomenological model,described by a sine-function equation, is proposed to define the relationship between flow stress and deformation parameters. A series of isothermal compressions for a carbon steel were carried out, as a case study, to obtain basic experimental *** of the new model were sequentially determined. The predicted results of the proposed model were compared with actual measured data. Good accuracy was found in the standard statistical parameters of correlation coefficient, root mean square error, and average absolute relative error with the values of 0.935, 7.137 MPa and 4.352%, respectively. Discussion of applications of different models in finite-element simulation demonstrated the benefit of the new model. When comparing the simulation results of three different deformation patterns with large strain, the new model showed 10%–20% lower predicted forming load than the original Arrhenius equation, and better applicability and reliability than modified Arrhenius equations.

关键词： phenomenological model high temperature large strain finite-element simulation

Low-Frequency Electroacupuncture Alleviates Chronic Constrictive Injury-Induced Mechanical Allodynia by Inhibiting NR2B Upregulation in Ipsilateral Spinal Dorsal Horn in Rats

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Chinese Journal of Integrative Medicine 2019年第6期25卷 462-467页

作者： zhao Wen-sheng JIANG zhen-ni SHI Hui XU Lu-lu YANG Yue WANG Ying-chao Department of Pain Medicine Hangzhou Red Cross Hospital Hangzhou (310003) China Department of Cardiology The Second Affiliated Hospital of Zhejiang University School of Medicine Hangzhou (310009) China Department of Acupuncture The Second Affiliated Hospital of Zhejiang University School of Medicine Hangzhou (310009) China The Second Clinical Medical College Zhejiang Chinese Medical University Hangzhou (310053) China Department of Clinical Research Center The Second Affiliated Hospital of Zhejiang University School of Medicine Hangzhou (310009) China

Objective: To study the effects of electroacupuncture(EA) in chronic constrictive injury(CCI) rat model and the expression of N-methyl-D-aspartate receptor type 2B(NR2B) in ipsilateral spinal dorsal horn in rats to explore the analgesic mechanisms of EA. Methods: According to the random number table, totally 180 rats were evenly divided into a sham group, a CCI group, and an EA group. CCI model was conducted with four4–0 chromic gut ligatures loosely ligated around the left sciatic nerve 1 cm above the trifurcation. Rats in the EA group received 2 Hz EA therapy bilaterally at acupoints of Zusanli(ST 36) and Sanyinjiao(SP 6) once daily(30 min/d) for 30 days after surgery. Paw withdrawal thresholds(PWTs) were measured on 0(baseline), 1, 3, 7, 15,30 days after surgery. Rats were sacri?ced on 0, 1, 3, 7, 15 and 30 days after surgery, and the L4–5 segments of spinal cord were removed to detect the expression of NR2B by immunohistochemistry and quantitative polymerase chain reaction. Results: PWTs in the CCI group were signi?cantly lower than the sham group at Day1–30 after surgery, and reached its lowest at Day 1(P<0.01). After EA treatment, the PWTs recovered rapidly and were signi?cantly higher than those in the CCI group on 3, 7, 15 and 30 days after surgery(P<0.01). The numbers of NR2B-immunoreactive cells of the CCI group signi?cantly increased after CCI surgery compared with the sham group(P<0.01). Compared with the CCI group, stimulation of EA markedly decreased the numbers of NR2B-immunoreactive cells at Day 3, 7, 15 and 30(P<0.05). In the sham group, NR2B mRNA was expressed at a low level. It increased after CCI surgery, which increased rapidly at Day 7(P<0.01) and reached its peak value at Day 15(P<0.01). After EA stimulation, relative quantity of NR2B mRNA expression was less than that in the CCI group at Day 15 and 30(P<0.05). Conclusions: Low frequency of EA had antinociceptive effect in CCI rat model. The analgesic effects of EA might be through the inhibit

关键词： sciatica electroacupuncture chronic constrictive injury spinal dorsal horn N-methyl-D-aspartate receptor type 2B Chinese medicine

Component fault diagnosis for nonlinear systems

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Journal of Systems Engineering and Electronics 2016年第6期27卷 1283-1290页

作者： Junjie Huang zhen Jiang Junwei zhao School of Mechanical and Power Engineering Henan Polytechnic University School of Mechatronics Engineering and Automation Shanghai University

In the field of fault diagnosis, the state equation of nonlinear system, including the actuator and the component, has been established. When the faults in the system appear, it is difficult to observe the fault isolation between the actuator and the component. In order to diagnose the component fault in the nonlinear systems, a novel strategy is proposed. The nonlinear state equation with only the component system is built on mathematical equations. The nonlinearity of the component equation is expanded and estimated with Taylor series. If the actuator is perfect, the anomaly of the state equations reflects the component fault. The fault feature index is defined to detect the component fault and the initial fault. The numerical examples of the component faults are simulated for multiple-input multiple-output(MIMO)nonlinear systems. The results show that the component faults,as well as the incipient faults, can be detected. Furthermore, the effectiveness of the proposed strategy is verified. This method can also provide a foundation for the component fault reconfiguration control.

关键词： multiple-input multiple-output(MIMO) nonlinear systems component faults fault feature index fault diagnosis