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Effect of Duty Cycle on the Characteristics of Pulse-Modulhted Radio-Frequency Atmospheric Pressure Dielectric Barrier Discharge

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Plasma Science and Technology 2012年第12期14卷 1069-1072页

作者： LI Xuechun wang Huan DING zhenfeng wang Younian School of Physics and Optoelectronic Technology Dalian University of TechnologyDalian 116024 China

Using a one-dimensional fluid model, the pulse-modulated radio-frequency dielectric barrier discharge in atmospheric helium is described. The influences of the pulse duty cycle on the discharge characteristics are studied. The numerical results show that the dependence of discharge characteristics on the duty cycle is sensitive in the region of around 40% duty cycle under the given simulation parameters. In the case of a larger duty cycle, the plasma density is higher, the discharge becomes more intense, but the power consumption is higher. When the duty cycle is lower, one can get a weaker discharge, lower plasma density and higher electron temperature in the bulk plasma. In practical applications, in order to get a higher plasma density and a lower power consumption, it is more important to choose a suitable duty cycle to modulate the RF power supply.

关键词： pulse-modulation simulation radio-frequency atmospheric pressure dielectric barrier discharge

Alveolar macrophages:Achilles’heel of SARS-CoV-2 infection

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Signal Transduction and Targeted Therapy 2022年第8期7卷 2936-2944页

作者： zhenfeng wang Shunshun Li Bo Huang Department of Immunology&National Key Laboratory of Medical Molecular Biology Institute of Basic Medical SciencesChinese Academy of Medical Sciences(CAMS)&Peking Union Medical College100005 BeijingChina Department of Immunology Basic Medicine CollegeChina Medical University110122 ShenyangLiaoningChina Department of Biochemistry&Molecular Biology Tongji Medical CollegeHuazhong University of Science&Technology430030 WuhanChina

The coronavirus disease 2019(COVID-19)pandemic has caused more than 6.3 million deaths to *** great efforts to curb the spread of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),vaccines and neutralizing antibodies are in the gloom due to persistent viral mutations and antiviral compounds face challenges of specificity and *** addition,vaccines are unable to treat already-infected individuals,and antiviral drugs cannot be used ***,exploration of unconventional strategies to curb the current pandemic is highly *** macrophages(AMs)residing on the surface of alveoli are the first immune cells that dispose of alveoli-invading *** findings demonstrate that M1 AMs have an acidic endosomal pH,thus favoring SARS-CoV-2 to leave endosomes and release into the cytosol where the virus initiates replication;in contrast,M2 AMs have an increased endosomal pH,which dampens the viral escape and facilitates delivery of the virus for lysosomal *** this review,we propose that AMs are the Achilles’heel of SARS-CoV-2 infection and that modulation of the endosomal pH of AMs has the potential to eliminate invaded SARS-CoV-2;the same strategy might also be suitable for other lethal respiratory viruses.

关键词： eliminate spite neutral

BEM/FDM Conjugate Heat Transfer Analysis of a Two-dimensional Air-cooled Turbine Blade Boundary Layer

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Journal of Thermal Science 2008年第3期17卷 199-206页

作者： wang zhenfeng Yan Peigang Guo Zhaoyuan Han Wanjin School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China

A coupled boundary element method （BEM） and finite difference method （FDM） are applied to solve conjugate heat transfer problem of a two-dimensional air-cooled turbine blade boundary layer. A loosely coupled strategy is adopted, in which each set of field equations is solved to provide boundary conditions for the other. The Navier-Stokes equations are solved by HIT-NS code. In this code, the FDM is adopted and is used to resolve the convective heat transfer in the fluid region. The BEM code is used to resolve the conduction heat transfer in the solid region. An iterated convergence criterion is the continuity of temperature and heat flux at the fluid-solid interface. The numerical results from the BEM adopted in this paper are in good agreement with the results of analytical solution and the results of commercial code, such as Fluent 6.2. The BEM avoids the complicated mesh needed in other computation method and saves the computation time. The results prove that the BEM adopted in this paper can give the same precision in numerical results with less boundary points. Comparing the conjugate results with the numerical results of an adiabatic wall flow solution, it reveals a significant difference in the distribution of metal temperatures. The results from conjugate heat transfer analysis are more accurate and they are closer to realistic thermal environment of turbines.

关键词： Conjugate heat transfer Boundary elements Finite difference Air-cooled gas turbine.

Simplification of the Plasma Load of Negative-Pulse-Bias Source Used in Arc Ion Plating

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Journal of Materials Science & Technology 2003年第Z1期19卷 97-98页

作者： Dong QI Ninghui wang Guoqiang LIN zhenfeng DING Department of Electrical and Electronics Engineering Dalian University of Technology Dalian 116024 China Department of Electrical and Electronics Engineering Dalian University of Technology Dalian 116024 China State Key Laboratory for Materials Modification by Laser Ion and Electron Beams Dalian University of TechnologyDalian 116024 China State Key Laboratory for Materials Modification by Laser Ion and Electron Beams Dalian University of TechnologyDalian 116024 China

Based on the voltage and current fluctuating phenomenon in the arc plasma load under the negative-pulse-bias, usingthe plasma physics theory and analysis of computer simulation expatiates that the nature of plasma load in vacuumarc plasma is a capacitance load caused by plasma sheath and can be simplified as a parallel unit composed of acapacitor and a resistor, which have exact and quantitative description in the plasma physics theory. It concludes thevalues of capacitance and resistance are thousand PF and hundred ohm from the result of simulation and *** a result, this has solved the key theoretical issues for the design of negative-pulse-bias source specifically used forvacuum arc ion plating.

关键词： Vacuum arc ion plating, Negative-pulse-bias, Plasma load

An effective method for improving the accuracy of Argo objective analysis

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Acta Oceanologica Sinica 2013年第7期32卷 66-77页

作者： ZHANG Chunling XU Jianping BAO Xianwen wang zhenfeng Institute of Marine Environment Ocean University of China Second Institute of Oceanography State Oceanic Administration State Key Laboratory of Satellite Oceanography Environment Dynamics Second Institute of OceanographyState Oceanic Administration Marine Hydrologic Meteorological Center Command of Navy East China Sea Fleet

Based on the optimal interpolation objective analysis of the Argo data, improvements are made to the em- pirical formula of a background error covariance matrix widely used in data assimilation and objective anal- ysis systems. Specifically, an estimation of correlation scales that can improve effectively the accuracy of Ar- go objective analysis has been developed. This method can automatically adapt to the gradient change of a variable and is referred to as ＂gradient-dependent correlation scale method＂. Its effect on the Argo objective analysis is verified theoretically with Gaussian pulse and spectrum analysis. The results of one-dimensional simulation experiment show that the gradient-dependent correlation scales can improve the adaptability of the objective analysis system, making it possible for the analysis scheme to fully absorb the shortwave information of observation in areas with larger oceanographic gradients. The new scheme is applied to the Argo data obiective analysis system in the Pacific Ocean. The results are obviously improved.

关键词： gradient-dependent correlation scale background error covariance optimal interpolation,spectrum analysis Argo data

Study of Longitudinal-Vertical Dynamics for In-Wheel Motor-Driven Electric Vehicles

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Automotive Innovation 2021年第2期4卷 227-237页

作者： Yechen Qin Ze Zhao zhenfeng wang Guofa Li School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China CAT ARC(Tianjin)Automotive Engineering Research Institute Co. LtdTianjin 300300China Institute of Human Factors and Ergonomics College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China

The in-wheel motor(IWM)-driven electric vehicles(EVs)attract increasing attention due to their advantages in dimensions and *** majority of the current studies on IWM are carried out with the assumption of an ideal actuator,in which the coupling effects between the non-ideal IWM and vehicle are *** paper uses the braking process as an example to investigate the longitudinal-vertical dynamics of IWM-driven EVs while considering the mechanical-electrical coupling ***,a nonlinear switched reluctance motor model is developed,and the unbalanced electric magnetic force(UEMF)induced by static and dynamic mixed eccentricity is ***,the UEMF is decomposed into longitudinal and vertical directions and included in the longitudinal-vertical vehicle *** coupling dynamics are demonstrated under different vehicle braking scenarios;numerical simulations are carried out for various road grades,road friction,and vehicle velocities.A novel dynamics vibration absorbing system is adopted to improve the vehicle ***,the simulation results show that vehicle vertical dynamic performance is enhanced.

关键词： Mechanical-electrical coupling Longitudinal-vertical dynamics In-wheel motor Suspension system

Evolution of deepwater sedimentary environments and its implication for hydrocarbon exploration in Qiongdongnan Basin, northwestern South China Sea

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Acta Oceanologica Sinica 2015年第4期34卷 1-10页

作者： wang zhenfeng JIANG Tao ZHANG Daojun wang Yahui ZUO Qianmei HE Weijun Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of Geosciences Kochi Institute for Core Sample Research Japan Agency for Marine-Earth Science and Technology

Over the past several years, a number of hydrocarbon reservoirs have been discovered in the deepwater area of Qiongdongnan Basin, northwestern South China Sea. These oil/gas fields demonstrate that the evolution of the deepwater sedimentary environment are controlling the formation and distribution of large-scale clastic reservoirs. Integration between seismic and borehole data were necessary to best clarify the distribution and quality of these deepwater reservoirs. Geochemical and paleobiological evidence from discrete samples was also applied to document specific information regarding the sedimentary environment. Results show that the Qiongdongnan Basin has existed as a thriving marine environment since Oligocene, when several rifting depressions developed throughout the entire Qiongdongnan Basin. Triggered by the faults activities, several distinct provenances supplied the coarse sediments, transporting and depositing them in deep parts of the rifting depressions. A fan delta system then formed nearby the source in the deeper area of these rifting depressions. The sedimentary environment of Qiongdongnan gradiationally became deepwater since early Miocene. Consequently, abundances of sediments were transported from Hainan Island and Southern Uplift, and then sunk into the basin center. The submarine fans revealed by many boreholes in this area verified them as good reservoir. Because the area reached its lowest sea level at late Miocene and the Southern Uplift subsidenced under sea level, not providing any sediment, so that the carbonate mesa and biorhythms characteristic of this area also developed during this period. In the west part of Qiongdongnan Basin, sediments transported from Vietnam increased in response to the Tibetan Uplift. Consequently, a central canyon developed along the center of Qiongdongnan Basin, which has been confirmed by several boreholes as a favorable hydrocarbon reservoir. The clarification of the deepwater sedimentary environment’s evol

关键词： deepwater environment Qiongdongnan Basin hydrocarbon exploration central canyon submarine fan

Structure and kinematic analysis of the deepwater area of the Qiongdongnan Basin through a seismic interpretation and analogue modeling experiments

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Acta Oceanologica Sinica 2015年第4期34卷 32-40页

作者： SUN Zhen wang zhenfeng SUN Zhipeng wang Zhangwen ZHANG Wei HE Lijuan Key Laboratory of Chinese Academy of Sciences for Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of Sciences Zhanjiang Branch of China National Offshore Oil Corporation Limited Shandong Province Geological Prospecting Institute China Chemical Geology and Mine Bureau

Located at the northwest continental slope of the South China Sea, the Qiongdongnan Basin bears valley-shaped bathymetry deepening toward east. It is separated from the Yinggehai Basin through NW-trending Indo-China-Red River shear zone, and connected with NW subsea basin through the Xisha Trough. Along with the rapid progress of the deepwater exploration, large amounts of high resolution geophysical and geological data were accumulated. Scientific researches about deepwater basins kept revealing brand new tectonic and sedimentary discoveries. In order to summarize the structural features and main controlling factors of the deepwater Qiongdongnan Basin, a series of researches on basin architecture, fault activities, tectonic deformation and evolution were carried out. In reference to analogue modeling experiments, a tectonic situation and a basin formation mechanism were discussed. The researches indicate that：the northern boundary of the Qiongdongnan Basin is strongly controlled by No. 2 fault. The overlapping control of two stress fields from the east and the west made the central depression zone extremely thinned. Combined with the changed stress field, the segmentation of a preexisting weakness zone made the sags in the east experiencing different rifting histories from the west ones. The NE-trending west segment of the Qiongdongnan Basin experienced strong rifting during Eocene, while the roughly EW-trending sags in the east segment show strong rifting during late Eocene and early Oligocene. Local structures such as NW-trending basal fault and inherited uplifts controlled the lateral segmentation. So first order factors such as regional stress field and preexisting weakness zone controlled the basin zonation, while the second order factors determined the segmentation from east to west.

关键词： rifting structure basin formation mechanism profile interpretation analogue modeling experiments Qiongdongnan Basin

Effect of Tire Repeated Root Modal on Tire Modelling with Experimental Modal

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Journal of Beijing Institute of Technology 2017年第1期26卷 67-74页

作者： zhenfeng wang Yongchang Du Mingming Dong Liang Gu School of Mechanical Engineering Beijing Institute of Technology State Key Laboratory of Automotive Safety and Energy Tsinghua University

The effect of tire repeated root modal（RRM）on tire modeling with an experimental modal is ***,a radial tire with radial and tangential RRMs is tested and *** multi-point exciting of the radial tire,a multiple reference frequency domain method based on a least squares（LMS PolyMAX）algorithm is used to identify modal ***,modal stability diagram（MSD）,modal indication function（MIF）and modal assurance criteria（Auto-MAC）matrix are utilized to induce multiple inputs multiple outputs（MIMO）frequency response function（FRF）*** tests reveal that notable repeated roots exist in both radial and tangential response *** modal frequencies and damping factors are approximately the same,the amplitudes of modal vectors are in the same order of magnitude,and the mode shapes are *** on the works mentioned,the method of trigonometric series modal shapes fitting is adopted,the effects of RRM model on tire modeling with a vertical experimental modal are *** final results show that the effects of considering the RRM shapes are equivalent to the tire mode shapes depended on rotating the tire’s different exciting points during tire modeling,and since considering the RRM,the tire mode shapes can be unified and fixed during tire modeling.

关键词： modal test repeated root modal ploy MAX method tire model