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Effect of attack angle on the electromagnetic wave transmission characteristics in the hypersonic plasma sheath of a re-entry vehicle
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作者 Xin AI Qiuyue NIE +4 位作者 Zhonglin ZHANG Peiqi CHEN Shulei ZHENG Changshi YAN Guoqiang WEI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第12期49-62,共14页
The attack angle may greatly affect the hypersonic plasma sheaths around the re-entry vehicle,thereby affecting the transmission characteristics of electromagnetic(EM)waves in the sheaths.In this paper,we propose an i... The attack angle may greatly affect the hypersonic plasma sheaths around the re-entry vehicle,thereby affecting the transmission characteristics of electromagnetic(EM)waves in the sheaths.In this paper,we propose an integrated three-dimensional(3D)model with various attack angles and realistic flying conditions of radio attenuation measurement C-II(RAM C-II)re-entry tasks for analyzing the effect of the attack angle on the transmission characteristics of EM waves in the sheaths.It is shown that the electron density and collision frequency of the sheath on the windward side can be increased by an order of magnitude with the increase of the attack angle.Meanwhile,the thickness of the sheath on the leeward side is increased where the electron density and collision frequency are reduced.The EM waves are mainly reflected on the windward plasma sheath due to the cutoff effect,and the radio-frequency(RF)blackout is mitigated if the antenna is positioned on the leeward side.Thus,by planning the trajectory properly and installing the antenna accordingly during the re-entry,it is possible to provide an approach for mitigation of the RF blackout problem to an extent. 展开更多
关键词 attack angle hypersonic plasma sheath re-entry vehicle transmission characteristics
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Morphological and biochemical characteristics associated with autophagy in gastrointestinal diseases 被引量:5
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作者 Yi-Fan Chang Jia-Jing Li +4 位作者 Tao Liu Chong-Qing Wei Li-Wei Ma Vladimir N Nikolenko Wei-Long Chang 《World Journal of Gastroenterology》 SCIE CAS 2024年第11期1524-1532,共9页
Autophagy is a cellular catabolic process characterized by the formation of double-membrane autophagosomes.Transmission electron microscopy is the most rigorous method to clearly visualize autophagic engulfment and de... Autophagy is a cellular catabolic process characterized by the formation of double-membrane autophagosomes.Transmission electron microscopy is the most rigorous method to clearly visualize autophagic engulfment and degradation.A large number of studies have shown that autophagy is closely related to the digestion,secretion,and regeneration of gastrointestinal(GI)cells.However,the role of autophagy in GI diseases remains controversial.This article focuses on the morphological and biochemical characteristics of autophagy in GI diseases,in order to provide new ideas for their diagnosis and treatment. 展开更多
关键词 AUTOPHAGY Morphological study Biochemical characteristics Subcellular structure transmission electron microscopy Gastrointestinal diseases
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Dynamic Characteristics of Transmission System for the Internal Grinder 被引量:2
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作者 伍建国 孙庆鸿 +2 位作者 毛海军 郁文凯 蔡英 《Journal of Southeast University(English Edition)》 EI CAS 2002年第4期302-305,共4页
The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relations... The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new ... 展开更多
关键词 transmission system dynamic characteristic modal flexibility elasticity distribution rate
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A study on characteristic indexesof railway ballast bed underhigh-frequency radar
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作者 Shilei Wang Zhan Peng +2 位作者 Guixian Liu Weile Qiang Chi Zhang 《Railway Sciences》 2023年第1期33-47,共15页
Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of rai... Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km1,and the computational efficiency of other indexes is 5 s$km1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures. 展开更多
关键词 Ballasted track Ballast bed high-frequency radar TEST Time–frequency characteristics characteristic indexes
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Transmission characteristics of Tomato chlorosis virus (ToCV) by Bemisia tabaci MED and its effects on host preference of vector whitefly 被引量:5
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作者 WEI Ke-ke LI Jie +2 位作者 DING Tian-bo LIU Tong-xian CHU Dong 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2019年第9期2107-2114,共8页
The epidemiology of Tomato chlorosis virus(ToCV)in China is closely associated with its vector whitefly,Bemisia tabaci(Gennadius)MED.However,the transmission characteristics of ToCV by B.tabaci MED remain poorly under... The epidemiology of Tomato chlorosis virus(ToCV)in China is closely associated with its vector whitefly,Bemisia tabaci(Gennadius)MED.However,the transmission characteristics of ToCV by B.tabaci MED remain poorly understood.In this study,we analyzed:1)the horizontal and vertical transmission of ToCV by B.tabaci MED whiteflies;2)the acquisition of ToCV by male and female B.tabaci MED whiteflies after different feeding durations;3)the transmission efficacy of viruliferous male and female B.tabaci MED whiteflies after different inoculation access periods(IAPs);4)the retention of ToCV by viruliferous male and female B.tabaci MED whiteflies after a 48 h acquisition access period(AAP);and 5)the effects of ToCV on host choice of healthy or ToCV-infected tomato plant of viruliferous and non-viruliferous B.tabaci MED at different time points.Our results showed that:1)viruliferous males could not transfer ToCV to non-viruliferous females,and vice versa,viruliferous females could not pass on ToCV to non-viruliferous males.ToCV could not be detected in the F1 generation adults;2)ToCV could be detected within 4.0%of females or males after a 20 min AAP;3)ToCV could be detected in 33.3%of tomato plants inoculated by 10 viruliferous males or females with IAPs of 20 or 30 min;4)the maximum retention time in females was 7 and 5 days in males;and 5)non-viruliferous B.tabaci MED did not show a preference for ToCV-infected tomato plants or healthy tomato plants.However,viruliferous B.tabaci MED whiteflies did prefer to settle on healthy tomato plants over ToCV-infected tomato plants.These findings will be helpful to better understand the epidemiology of the recently emerged plant virus,ToCV,in tomato fields in China. 展开更多
关键词 TOMATO CHLOROSIS VIRUS BEMISIA TABACI MED transmission characteristics preference
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Numerical modeling of DPSK pressure signals and their transmission characteristics in mud channels 被引量:11
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作者 Shen Yue Su Yinao +2 位作者 Li Gensheng Li Lin Tian Shouceng 《Petroleum Science》 SCIE CAS CSCD 2009年第3期266-270,共5页
A numerical model and transmission characteristic analysis of DPSK (differential phase shift keying) pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry,... A numerical model and transmission characteristic analysis of DPSK (differential phase shift keying) pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry, a logical control signal is built from a Gate function sequence according to the binary symbols of transmitted data and a phase-shift function is obtained by integrating the logical control signal. A mathematical model of the DPSK pressure signal is built based on principles of communications by modulating carrier phase with the phase-shift function and a numerical simulation of the pressure wave is implemented with the mathematical model by MATLAB programming. Considering drillpipe pressure and drilling fluid temperature profile along drillpipes, the drillpipe of a vertical well is divided into a number of sections. With water-based drilling fluids, the impacts of travel distance, carrier frequency, drillpipe size, and drilling fluids on the signal transmission were studied by signal transmission characteristic analysis for all the sections. Numerical calculation results indicate that the influences of the viscosity of drilling fluids and volume fraction of gas in drilling fluids on the DPSK signal transmission are more notable than the others and the signal will distort in waveform with differential attenuations of the signal frequent component. 展开更多
关键词 Measurement while drilling (MWD) MODULATION binary symbol mathematical model numerical simulation differential phase shift keying (DPSK) signal transmission characteristics
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Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application 被引量:4
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作者 Weihao TIE Cui MENG +4 位作者 Chengguang ZHAO Xiaogang LU Jun XIE Dan JIANG Zirang YAN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第9期110-121,共12页
We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line(GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate,... We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line(GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters(rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a?>?90 k V RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m^-1 and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge. 展开更多
关键词 gyro-magnetic nonlinear transmission line (GNLTL) SHARPENING characteristics sub-nanosecond pulse high REPETITION rate
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Analysis of the carbon dioxide mole fraction variation and its transmission characteristics in Taiyuan 被引量:5
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作者 ZHANG Fengsheng ZHU Lingyun +2 位作者 YAN Shiming GAO Xing’ai PEI Kunning 《Atmospheric and Oceanic Science Letters》 CSCD 2020年第4期363-370,共8页
Based on the concentrations of CO2,PM2.5 and PM1.0,and conventional meteorological observation data from 2016 to 2018 at Taiyuan station,which belongs to the Shanxi greenhouse gas observation network,the CO2 concentra... Based on the concentrations of CO2,PM2.5 and PM1.0,and conventional meteorological observation data from 2016 to 2018 at Taiyuan station,which belongs to the Shanxi greenhouse gas observation network,the CO2 concentration monthly and daily distribution characteristics,the weekend effect,and the variation characteristics on haze days and non-haze days,are analyzed.By using the Hybrid Single-Particle Lagrangian Integrated Trajectorymodel(backward trajectory model)and surface wind data,the transmission characteristics of atmospheric CO2 in Taiyuan are studied in various seasons.The results show that,in Taiyuan,the CO2 mole fraction in autumn and winter is higher than that in spring and summer,and on haze days is higher than that on non-haze days.The diurnal variation characteristic of CO2mole fraction in each season is‘single peak and single valley’with the peak value around 0700(hereafter refers to Beijing Time)and the valley value around 1600.The CO2 mole fraction on workdays is slightly higher than that on non-workdays and obviously different around 0800 of the early peak.Horizontal diffusion can reduce the CO2 mole fraction,while breezy weather is not beneficial to CO2 diffusion.The wind direction and speed in the upper levels are different from those near the surface,and the close air masses in the southwest–west–northwest sector raise the CO2 concentration in Taiyuan obviously.This indicates that the CO2 in Taiyuan is mainly contributed by local sources. 展开更多
关键词 Atmospheric carbon dioxide mole fraction variation transmission characteristics Taiyuan
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Study on optical constants inversion and infrared transmission characteristics of aerosol particles 被引量:1
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作者 王希影 齐宏 +1 位作者 牛臣基 阮立明 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2011年第6期1-6,共6页
Based on the experimental infrared spectral transmittances,an inverse model has been developed to determine the optical constants of the aerosol particles (SiO2 and Al2O3).Combined with the Mie theory and Kramers-Kron... Based on the experimental infrared spectral transmittances,an inverse model has been developed to determine the optical constants of the aerosol particles (SiO2 and Al2O3).Combined with the Mie theory and Kramers-Kronig (K-K) relations,the complex refractive indices of the SiO2 and Al2O3 particles are retrieved.The effects of the measurement errors on the inverse results are also investigated.With the optical constants inversed from the experiment,the discrete ordinate method (DOM) is used to calculate the infrared transmission characteristics of the aerosol particle cloud.Considering the multi-scattering and self-emission of the particles,the equivalent transmittance ratio (ETR) is suggested to evaluate the infrared transmission characteristics of the aerosol particles.Particular attention is given to analyze the effects of the volume fraction and diameters on infrared transmission characteristics.When the volume fraction is larger than 0.001,the particle diameter has little effect on the infrared transmission characteristics.For the uniform monodisperse particles in the detection waveband range of 3-5 μm and 8-12 μm,there exists a critical diameter where the ETR reaches the minimum value.In addition,the ETR of 3-5 μm is smaller than that of 8-12 μm with the same volume fraction and particle diameter. 展开更多
关键词 aerosol particles optical constants INVERSION infrared transmission characteristics
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Lubrication characteristics of cycloid pin wheel transmission of RV reducer 被引量:1
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作者 HAN Ju LI Wei QIAO Ze-long 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第2期398-417,共20页
In order to analyze the lubricating characteristics at different meshing points in the cycloid pin wheel transmission process,the cycloid gear teeth were discretized,combined with the kinematic analysis of the cycloid... In order to analyze the lubricating characteristics at different meshing points in the cycloid pin wheel transmission process,the cycloid gear teeth were discretized,combined with the kinematic analysis of the cycloid pin gear transmission and the contact analysis of the gear teeth.The progressive mesh densification method(PMD)was used to numerically solve the film thickness.The influence of the design parameters and process parameters on the lubrication characteristics was analyzed.The elastohydrodynamic lubrication and mixed lubrication characteristics at different contact points were obtained.The optimal meshing area of the cycloid gear tooth was determined,and the film thickness ratio,contact load ratio,maximum contact pressure at different points,average film thickness and roughness after contact deformation were analyzed.The conclusion of this study provides effective guidance for the research on the modification of cycloid gear teeth. 展开更多
关键词 cycloid pin wheel transmission tooth modification lubrication characteristics
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Influence of intra-cavity loss on transmission characteristics of fiber Bragg grating Fabry–Perot cavity 被引量:2
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作者 王迪 丁孟 +5 位作者 皮浩洋 李璇 杨飞 叶青 蔡海文 魏芳 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第2期380-384,共5页
A theoretical model of the fiber Bragg grating Fabry–Perot(FBG-FP) transmission spectrum considering loss of FBG and intra-cavity fiber is presented. Several types of FBG-FPs are inscribed experimentally, and their... A theoretical model of the fiber Bragg grating Fabry–Perot(FBG-FP) transmission spectrum considering loss of FBG and intra-cavity fiber is presented. Several types of FBG-FPs are inscribed experimentally, and their spectra are measured.The results confirm that weak intra-cavity loss is enhanced at the resonance transmission peak, that is, loss of transmission peaks is observably larger than other wavelengths. For FBG-FPs with multi resonance peaks, when the resonance peak wavelength is closer to the Bragg wavelength, the more significant loss effect of resonance transmission peak is exhibited.The measured spectra are fitted with the presented theoretical model. The fitted coefficient of determinations are near 1,which proves the validity of the theoretical model. This study can be applied to measure FBG loss more accurately, without a reference light. It can play an important role in FBG and FBG-FP writing process optimization and application parameter optimization. 展开更多
关键词 fiber Bragg grating Fabry–Perot cavity intra-cavity loss transmission characteristics
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Transmission Spectral Characteristics of Photonic Crystals Milled in Annealed Proton-Exchange LiNbO_3 Waveguide 被引量:2
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作者 赵全周 张德龙 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第3期49-52,共4页
Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal s... Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal shape and hybrid shape of holes are theoretically analyzed. Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate (LiNbO3 ), a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode, and useful transmission spectra with strong contrast and sharp band edges are achieved. 展开更多
关键词 LN transmission Spectral characteristics of Photonic Crystals Milled in Annealed Proton-Exchange LiNbO3 Waveguide
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Analysis on the fault characteristics of three-phase short-circuit for half-wavelength AC transmission lines 被引量:2
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作者 Xuankun Song Teng Feng +4 位作者 Liu Han Travis MSmith Xinzhou Dong Wenxuan Liu Rui Zhang 《Global Energy Interconnection》 2018年第2期115-121,共7页
Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the constructi... Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the construction and operation of HWACT to analyze its fault features and corresponding protection technology. In this paper, the steady-state voltage and current characteristics of the bus bar and fault point and the steady-state overvoltage distribution along the line will be analyzed when a three-phase symmetrical short-circuit fault occurs on an HWACT line. On this basis, the threephase fault characteristics for longer transmission lines are also studied. 展开更多
关键词 Half-wavelength AC transmission Fault characteristics Three-phase short-circuit Fault distance OVERVOLTAGE
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One modified method of characteristics used to analyze the multiconductor transmission lines
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作者 Fu Jiwei Hou Chaozhen Dou Lihua 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2006年第1期65-70,共6页
To solve the coupling effect of multiconductor transmission lines excited by external electromagnetic wave, the modified method of characteristics is proposed. The modified method of characteristics which can compute ... To solve the coupling effect of multiconductor transmission lines excited by external electromagnetic wave, the modified method of characteristics is proposed. The modified method of characteristics which can compute the terminal induced voltages excited by the external electromagnetic wave when the terminal networks or intereonnection networks contain the dynamic elements is introduced. The simulation results indicate that the modified method can analyze the terminal induced voltages when the terminal networks or the interconnection networks contain the dynamic elements excited by the external electromagnetic wave. And the results are compared with the results acquired by FDTD method, the two results are completely same. So one effective modified method is implemented to compute the transmission lines. 展开更多
关键词 multiconductor transmission line the method of characteristics dynamic elements.
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Analysis of the Relationship Between the Meshing Stiffness and the Inherent Characteristics of Planetary Gear Transmission Mechanism
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作者 Qiang Zhang Rong He +1 位作者 Yudong Zhang Jin Xu 《Journal of Beijing Institute of Technology》 EI CAS 2019年第4期811-818,共8页
According to the relationship between the meshing stiffness and the inherent characteristics of a seven-speed three-row coupled planetary transmission mechanism,a equivalent concentrated mass dynamics model of the pla... According to the relationship between the meshing stiffness and the inherent characteristics of a seven-speed three-row coupled planetary transmission mechanism,a equivalent concentrated mass dynamics model of the planetary transmission mechanism is established.The natural frequency of the planetary gear train at a specific gear is calculated and extracted.The relationship between the meshing stiffness of each row and the natural frequency of the system is analyzed,thereby avoiding possible resonance behavior by changing the meshing stiffness.These results show that the meshing stiffness,in its range of possible values,has nearly no effect on the low order natural frequency(<4.000.Hz),and that the time-varying meshing stiffness mainly affects the natural frequencies of the higher-and middle-order parts of the system.Changes of the natural frequencies lead to the change of the system's corresponding vibration mode,which will change the vibration situation of the system. 展开更多
关键词 planetary transmission DYNAMICS meshing stiffness inherent characteristics
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Dynamic Engaging Characteristics of Wet Clutch in Automatic Transmission 被引量:1
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作者 刘艳芳 郭伟 +1 位作者 张婧 徐向阳 《Journal of Donghua University(English Edition)》 EI CAS 2015年第3期357-362,共6页
Wet clutch is an important shifting component in automatic transmission,and its properties will affect the gear shift performance. By comparing the calculated and test results,the static friction torque model was prov... Wet clutch is an important shifting component in automatic transmission,and its properties will affect the gear shift performance. By comparing the calculated and test results,the static friction torque model was proved to be capable of describing the real pressure and torque only in the situation of high-energy engagement.Therefore,a dynamic torque model was proposed on basis of hydrodynamic properties between friction surfaces, in which the clutch engagement was divided into three phases for hydrodynamic lubrication, mixed lubrication, and mechanical contact. The proposed dynamic torque model was validated by comparing the calculated and test results. The effects of temperature,pressure,and pressure changing rate of automatic transmission fluid( ATF) on the clutch torque were analyzed. Based on these results,the clutchto-clutch torque control during shifting in automatic transmission was optimized,and as a result,the shifting comfort was significantly improved since the problems such as the fluctuation and sudden drop of the engine rotating speed during shifting were eliminated. 展开更多
关键词 automatic transmtsston wet clutch dynamiccharacteristics torque control FRICTION
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Experimental Studies on Impulse Flashover Characteristics of Tower Head Air Gaps of±1 000 kV DC Transmission Lines and 被引量:1
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作者 DING Yujian LIAO Weiming SUN Zhaoying SU Zhiyi 《中国电机工程学报》 EI CSCD 北大核心 2011年第34期I0010-I0010,共1页
关键词 英文摘要 内容介绍 编辑工作 期刊
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An Experimental Research to Study the Microwaves transmission Characteristics of Ablating Material in Arc-Heated Plasma Flow
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作者 程梅莎 董永晖 张嘉祥 《Plasma Science and Technology》 SCIE EI CAS CSCD 2001年第2期743-747,共5页
in this paper, an experimental research the effect of ablating material on the reflection and the transmission of microwaves in arc-heated plasma flow is presented by using the C band microwave measuring system. The ... in this paper, an experimental research the effect of ablating material on the reflection and the transmission of microwaves in arc-heated plasma flow is presented by using the C band microwave measuring system. The results show that the ablating material with accidented surface and its high temperature have remarkably affected the reflection and the transmission of microwaves. The experiment proves that the system has outstanding precision and reliability. 展开更多
关键词 An Experimental Research to Study the Microwaves transmission characteristics of Ablating Material in Arc-Heated Plasma Flow Arc high
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Aero-Hydrodynamic Coupled Dynamic Characteristics of Semi-Submersible Floating Offshore Wind Turbines Under Inflow Turbulence 被引量:2
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作者 JIANG Hai-rui BAI Xing-lan Murilo A.VAZ 《China Ocean Engineering》 SCIE EI CSCD 2023年第4期660-672,共13页
In this study,the frequency characteristics of the turbulent wind and the effects of wind-wave coupling on the low-and high-frequency responses of semi-submersible floating offshore wind turbines(FOWT)are investigated... In this study,the frequency characteristics of the turbulent wind and the effects of wind-wave coupling on the low-and high-frequency responses of semi-submersible floating offshore wind turbines(FOWT)are investigated.Various wave load components,such as first-order wave loads,combined first-and second-order difference-frequency wave loads,combined first-and second-order sum-frequency wave loads,and first-and complete second-order wave loads are taken into consideration,while different turbulent environments are considered in aerodynamic loads.The com-parison is based on time histories and frequency spectra of platform motions and structural load responses and statistical values.The findings indicate that the second-order difference-frequency wave loads will significantly increase the natural frequency of low-frequency motion in the responses of the platform motion and structure load of the semi-submersible platform,which will cause structural fatigue damage.Under the action of turbulent wind,the influences of second-order wave loads on the platform motion and structural load response cannot be ignored,especially under extreme sea conditions.Therefore,in order to evaluate the dynamic responses of semi-submersible FOWT more accurately,the actual environment should be simulated more realistically. 展开更多
关键词 turbulence characteristics floating offshore wind turbines second-order hydrodynamic loads low-and high-frequency responses aero-hydrodynamic coupling
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STUDY ON THE VIBRATION CHARACTERISTIC OF THE METAL PUSHING BELT CONTINUOUSLY VARIABLE TRANSMISSION 被引量:1
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作者 Yang Wei Qin Datong Li Yilong Zhu Caichao The State Key Laboratory of Mechanical Transmission,Chongqing University 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2001年第2期175-178,183,共5页
The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i =0 5 and i=2 0. In order to solve the problem of the complicated of structure,the... The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i =0 5 and i=2 0. In order to solve the problem of the complicated of structure,the node node rod discrete finite element model is put forward and the whole system is simplified and established.The natural frequency and mode shape of system are solved by iterative Lanczos reduce method for sensitivity analysis in finite element model.The new method and the result can be used to improve the smoothness of the variable transmission system and to propose the theory for reducing noise at operation. 展开更多
关键词 Continuously variable transmission Finite element model Modal analysis Vibration characteristic
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