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Study on Static Deflection Model of MEMS Capacitive Microwave Power Sensors

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Chinese Journal of Electronics 2024年第5期33卷 1188-1195页

作者： ye jin Debo WANG College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology) Nanjing University of Posts and Telecommunications College of Integrated Circuit Science and Engineering Nanjing University of Posts and Telecommunications

In this paper, a static deflection model of MEMS cantilever beam is proposed, which can better study the force deformation of micro-electro-mechanical system(MEMS) cantilever beam and the output characteristics of capacitive microwave power sensor. The deflection curve is used to describe the deformation of the cantilever beam and then the overload power and sensitivity of this power sensor are derived. It is found that the overload power decreases with the beam length, and increases with the initial height of beam. The sensitivity increases with the beam length, and has a linear growth relationship with the measuring electrode width. A MEMS dual-channel microwave power sensor is designed, fabricated and measured. At a microwave signal frequency of 10 GHz, the sensitivity of the sensor is measured to be 0.11 V/W for the thermoelectric detection channel and 65.17 fF/W for the capacitive detection channel. The sensitivity calculated by the lumped model is 92.93 fF/W, that by the pivot model is 50.88 fF/W,and that by the deflection model proposed in this work is 75.21 fF/W. Therefore, the theoretical result of the static deflection model is more consistent with the measured result and has better accuracy than the traditional lumped model and pivot model.

关键词： Microwave measurement Micromechanical devices Microelectromechanical systems Sensitivity Voltage measurement Accuracy Deformation

PROTOTYPE SURFACE MICRO- PRECISION IN FUSED DEPOSITION MODELING PROCESS

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Chinese Journal of Mechanical Engineering 2007年第1期20卷 100-106页

作者： WANG Tianming XI Juntong jin ye School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

To aim at prototype parts fabricated with fused deposition modeling （FDM） process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is explained with three aspects concretely including the principle error of rapid prototyping （RP） process, the inherent characteristics of FDM process, and some mi- cro-scratches on the surface of the extruded fiber. Based on the micro-characters of section shape of the FDM prototype, a physical model reflecting the outer shape characters is abstracted. With the physical simplified and deduced, the evaluating equations of surface roughness are acquired. According to the FDM sample parts with special design for experimental measurement, the real surface roughness values of different inclined planes are obtained. And the measuring values of surface roughness are compared with the calculation values. Furthermore, the causes of surface roughness deviation between measuring values and calculation values are respectively analyzed and studied. With the references of analytic conclusions, the measuring values of the experimental part surface are revised, and the revised values nearly accord with the calculation values. Based on the influencing principles of FDM process parameters and special post processing of FDM prototype parts, some concrete measures are proposed to reduce the surface roughness of FDM parts, and the applying effects are better.

关键词： Rapid prototyping Fused deposition modeling Micro-precision Surface roughness Post processing sequence

PREDICTION OF PODDED PROPELLER CAVITATION USING AN UNSTEADY SURFACE PANEL METHOD

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Journal of Hydrodynamics 2008年第6期20卷 790-796页

作者： ye jin-ming XIONG Ying College of Naval Architecture and Power Naval University of Engineering Wuhan 430033 China

The unsteady sheet cavitation of podded propeller was predicted by using a surface panel method. The interaction between propeller and pod was treated with the iterative calculation of induced velocity potential, and the method of induced velocity potential can save a great deal of storage and computation time compared to the method of induced velocity. The induced velocity potential of unit singularity on every pod panel to every key blade panel and of unit singularity on every key blade panel and its wake panel to every pod panel were calculated when the key blade is at every angle position. Based on the wake model of the conventional single propeller, a new wake model of podded propeller was constructed. The propeller is analyzed only on the key blade in order to save computation time and memory space. The method can be used to calculate the hydrodynamics performance and cavitation of propeller in uniform and non-uniform inflows. It can give the unsteady force and cavitation shape of propeller. The propeller cavitation range determined by the present method agrees with the observation results of cavity image given in cavitation tunnel well, and this proves the practicability of the method.

关键词： pod propeller unsteady performance cavitation surface panel method

Effectiveness of Group-Based Interventions for Fall Prevention Among Community-Dwelling Older Adults—7 Regions,6 PLADs,China,2019–2020

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China CDC weekly 2023年第47期5卷 1047-1051,I0001页

作者： Yuliang Er Zhiming Lu ye jin Pengpeng ye Leilei Duan National Center for Chronic and Noncommunicable Disease Control and Prevention Chinese Center for Disease Control and PreventionBeijingChina Department of Epidemiology and Biostatistics Institute of Basic Medical Sciences Chinese Academy of Medical SciencesSchool of Basic Medicine Peking Union Medical CollegeBeijingChina

Summary What is already known about this topic?Many of the current studies focusing on fall prevention interventions have been conducted in hospital settings within a select few urban areas in China,thus yielding limi... 详细信息

关键词： prevention yielding urban

Unintentional Drowning Mortality Among Individuals Under Age 20—China,2013–2021

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China CDC weekly 2023年第47期5卷 1058-1062页

作者： Zi Li Xiao Deng ye jin Leilei Duan Pengpeng ye National Center for Chronic and Noncommunicable Disease Control and Prevention Chinese Center for Disease Control and PreventionBeijingChina

ABSTRACT Introduction:This study seeks to elucidate the evolving trend and identify disparities among subgroups in the mortality rate due to unintentional drowning in individuals under the age of 20 from the timeframe... 详细信息

关键词： subgroups China. identif

Acceleration of aging behavior and improvement of mechanical properties of extruded AZ80 alloy through(10–12) twinning

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Journal of Magnesium and Alloys 2023年第2期11卷 671-683页

作者： Hyun Ji Kim ye jin Kim Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

The effects of pre-existing {10–12} extension twins on the precipitation behavior of an extruded AZ80 material during aging and on its mechanical properties after peak aging are investigated. The material containing {10–12} twins-which are formed by compression before aging(twinned material)-has a finer grain size and higher dislocation density than the extruded material. Although the peak hardnesses of the twinned and extruded materials are almost the same, the time to reach the peak hardness is considerably shorter in the former material than in the latter(4 h and 24 h, respectively). In the twinned material, the high dislocation density of the {10–12} twins promotes continuous precipitation, which results in the formation of numerous fine Mg17Al12precipitates within the twins in the early stage of *** formation of these continuous precipitates reduces the driving force for discontinuous precipitation, which consequently suppresses the formation and growth of coarse Mg17Al12precipitates at the grain boundaries. Despite its shorter peak-aging time, the 4 h-peak-aged twinned material shows higher tensile strength and elongation than the 24 h-peak-aged extruded material. These higher mechanical properties of the former material are attributed primarily to the presence of more abundant fine continuous precipitates, which are effective in strengthening the material, and less abundant coarse discontinuous precipitates, which can act as crack initiation sites. These results demonstrate that the introduction of {10–12} twins into wrought Mg–Al-based alloys can accelerate the Mg17Al12precipitation kinetics considerably and improve the strength and ductility of the peak-aged alloys simultaneously.

关键词： AZ80 alloy Twin Aging Precipitation Tensile properties

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

Development of an ultrahard nanotwinned cBN micro tool for cutting hardened steel

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Science China(Technological Sciences) 2016年第6期59卷 876-881页

作者： CHEN Jun Yun jin Tian ye TIAN Yong Jun College of Vehicles and Energy Yanshan University College of Mechanical Engineering Yanshan University State Key Laboratory of Metastable Materials Science & Technology Yanshan University

Binderless nanotwinned cubic boron nitride(nt-cBN) synthesized from onion-structured BN precursors under high pressure and high temperature shows a very fine microstructure consisting of densely lamellar nanotwins(average thickness of 4 nm) within nanograins. The unique nanotwinned microstructure offers high hardness, wear resistance, fracture toughness, and thermal stability which are essential for advanced cBN tool materials. Thus, a circular micro tool of nt-cBN was fabricated using femtosecond laser contour machining followed by focused ion beam precision milling. Thereafter turning tests were performed on hardened steel using the studied micro tool. To evaluate the cutting performance, the machined surface quality and subsurface damage of the hardened steel were characterized. The wear mechanism of the nt-cBN micro tool was also investigated. It is found that the fabricated nt-cBN micro tool can generate high quality surface with surface roughness less than 7 nm and nanograin subsurface of about 500 nm deep. In addition, abrasive wear is found to be the dominant wear mechanism of the nt-cBN micro tool in turning hardened steel. These results indicate that nt-cBN has outstanding potential for ultra-precision cutting hardened steel.

关键词： nanotwinned cBN tool fabrication cutting tool micro machining hardened steel

Using air curtains to reduce short-range infection risk in consulting ward: A numerical investigation

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Building Simulation 2021年第2期14卷 325-335页

作者： jin ye Hua Qian Jianchao Ma Rong Zhou Xiaohong Zheng School of Energy and Environment Southeast UniversityNanjing210096China Engineering Research Center of BEEE Ministry of Education of ChinaNanjing210096China First Affiliated Hospital of Guangzhou Medical University Guangzhou510000China Guangzhou Angel Biosafety Co. LtdGuangzhou510000China Jiangsu Provincial Key Laboratory of Solar Energy Science and Technology Nanjing210096China

Air curtains is promising in reducing the short-range infection risk in *** quantitatively evaluate its performance,this paper explores air curtains equipped on normal consulting desk to avoid doctor’s direct exposure to the patient exhaled pollutants.A numerical investigation is conducted to evaluate the effects of supply air velocity and angle on cutting off *** results show that the average mass fraction of exhaled pollutants decreases significantly(70%–90%)in the consulting ward,indicating satisfying performance of air *** supply air velocity is demonstrated to be conducive in forming full air curtains,whereas an excessively high supply air velocity may be of adverse effects by entraining exhaled ***,the supply air angle is also critical due to its coupling with supply air *** is found that larger angle(0°–40°)is better where velocity is less than 3 m/s,otherwise a small angle(20°)is preferable where velocity is larger than 3 m/*** flow could be well suppressed at the supply air angle 20°but moves over air curtains at 40°.This study can provide effective and intuitive guidance in applying air curtains in consulting wards.

关键词： air curtains consulting ward cutting off performance numerical investigation