检索结果-南通市图书馆

Diffusion Coefficient at resonance frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Electromagnetic Analysis and Applications 2020年第10期12卷 145-158页

作者： Amadou Mar Ndiaye Sega Gueye Mame Faty Mbaye Fall Gora Diop Amadou Mamour Ba Mamadou Lamine Ba Ibrahima Diatta Lemrabott Habiboullah Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal Ecole Polytechnique de Thiès Thiès Sénégal Département Génie Electrique Ecole Supérieure Polytechnique de Nouakchott Nouakchott Mauritanie

The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (D(ω, B), in the (p) base leads to maximum values (Dmax) at resonance frequencies (ωr). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, ωr and B, are then established, and will be data for industrial development of low-cost solar cells for specific use.

关键词： Silicon Solar Cell resonance frequency Magnetic Field Recombination Velocity Base Thickness

ANALYSIS OF PIEZOELECTRIC ENERGY HARVESTING DEVICE WITH ADJUSTABLE resonance frequency

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Electronics(China) 2012年第Z2期 310-318页

作者： Jiang Lei Li Yuejuan* Marvin Cheng* (School of Mechanical Electronic & Information Engineering, China University of Mining & Technology, Beijing 100083, China) *(Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26505, U.S.A)

关键词： Piezoelectric Energy harvesting resonance frequency

STATISTICAL ANALYSIS OF resonance frequency ERROR FOR ULTRASONIC WELDING MACHINE TRANSDUCER

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

STATISTICAL ANALYSIS OF RESONANCE FREQUENCY ERROR FOR ULTRAS...

Analysis of iris-loaded resonance cavity in miniaturized maser

2006年中国机械工程学会年会暨中国工程院机械与运载工程学部首届年会

作者： ZHANG Yundian, WANG Qifang Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, PR China

Ultrasonic welding technology, a high efficiency and energy saving technology, has been widely used in industry. Piezoelectric transducer is the key component in ultrasonic welding machine, and the re

关键词： Ultrasonic welding piezoelectric transducer resonance frequency Normal distribution.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第5期29卷 188-193页

作者： Zu-Gen Guo Yong Zhang Tao Tang Zhan-Liang Wang Yu-Bin Gong Fei Xiao Hua-Rong Gong National Key Laboratory of Science and Technology on Vacuum Electronics School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu 610054China

The size reduction of atomic clocks is a long-standing research *** atomic clocks such as passive hydrogen masers(PHMs)and compact rubidium masers(CRMs)use iris-loaded resonance cavities(IRCs)as their microwave cavities because they can dramatically reduce the radical sizes of the atomic *** this paper,the electromagnetic characteristic of the IRC is investigated by a theoretical model based on electromagnetic field *** formulas to calculate the resonance frequency,quality factor,and magnetic energy filling factor are *** relationship between the IRC structure and its electromagnetic characteristic is *** theoretical calculation results accord well with the electromagnetic software simulations and experimental *** results in this paper should be helpful in understanding the physical mechanism of the IRC and designing the atomic clocks.

关键词： maser iris-loaded resonance cavity resonance frequency quality factor magnetic energy filling factor

Study of a Dual-sided Multiple Fans System with a Piezoelectric Actuator

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2015年第5期24卷 432-441页

作者： Hsiao-Kang Ma Yi-Tseng Li Ching-Po Lin Department of Mechanical Engineering Taiwan University

A dual-sided multiple fans system with a piezoelectric actuator （＂D-MFPA＂）, which is able to drive eight passive vibrating fans and provide two-directional air flows by using only one piezoelectric actuator, has been investigated in this study. Moreover, two types of the fan designs, viz. magnetic fan （MF） and composite magnetic fan （CMF） were also explored. In the investigation of the MF, the results indicated that the resonance frequency of the D-MFPA increased from 27.6 Hz to 66 Hz as the length of the carbon fiber plate （L） decreased from 55 mm to 35 mm. It also decreased the amplitude of the D-MFPA from 12.4mm to 4.8 mm. For CMF, the results showed that the resonance frequency decreased when the length of the Mylar plate （Et） increased, and the maximum decrease was from 66 Hz to 45 Hz when L= 35 mm and Er= 30 mm. Dimensionless heat convection number （MD_MFPA） was defined to describe and quantify the improvement in the thermal performance. The results showed that the optimal MO-MFPA of the single piezoelectric fan was 1,58 for cooling one heat source. By contrast, under the same power consumption, the D-MFPA not only cooled two heat sources but also displayed better thermal performance.

关键词： D-MFPA resonance frequency composite magnetic fan thermal performance

Prediction of Vibration Characteristics in Beam Structure Using Sub-Scale Modeling with Experimental Validation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第5期28卷 928-934页

作者： ZAI Behzad Ahmed SAMI Saad KHAN M Amir AHMAD Furqan PARK Myung Kyun Structure Design and Development Directorate Institute of Space Technology Department of Civil and Environmental Engineering KAIST Department of Mechanical Engineering Myongji University

Geometric or sub-scale modeling techniques are used for the evaluation of large and complex dynamic structures to ensure accurate reproduction of load path and thus leading to true dynamic characteristics of such structures. The sub-scale modeling technique is very effective in the prediction of vibration characteristics of original large structure when the experimental testing is not feasible due to the absence of a large testing facility. Previous researches were more focused on free and harmonic vibration case with little or no consideration for readily encountered random vibration. A sub-scale modeling technique is proposed for estimating the vibration characteristics of any large scale structure such as Launch vehicles, Mega structures, etc., under various vibration load cases by utilizing precise scaled-down model of that dynamic structure. In order to establish an analytical correlation between the original structure and its scaled models, different scale models of isotropic cantilever beam are selected and analyzed under various vibration conditions（ i.e. free, harmonic and random） using finite element package ANSYS. The developed correlations are also validated through experimental testing The prediction made from the vibratory response of the scaled-down beam through the established sets of correlation are found similar to the response measured from the testing of original beam structure. The established correlations are equally applicable in the prediction of dynamic characteristics of any complex structure through its scaled-down models. This paper presents modified sub-scale modeling technique that enables accurate prediction of vibration characteristics of large and complex structure under not only sinusoidal but also for random vibrations.

关键词： sub-scale modeling resonance frequency vibration characteristics scale factors power spectral density

Design of a low-frequency miniaturized piezoelectric antenna based on acoustically actuated principle

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第7期31卷 565-572页

作者： Yong Zhang Zhong-Ming Yan Tian-Hao Han Shuang-Shuang Zhu Yu Wang Hong-Cheng Zhou School of Electrical Engineering Southwest Jiaotong UniversityChengdu 610000China Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle Ministry of EducationChengdu 610000China

An acoustically actuated piezoelectric antenna is proposed for low frequency(LF)band in this *** proposed antenna is theoretically calculated,numerically optimized by the finite element method(FEM),and experimentally *** measurement results show that the near-field radiation pattern of the piezoelectric antenna is similar to that of the electric dipole *** radiation efficiency of the piezoelectric antenna is 3-4 orders of magnitude higher than that of electrically small antenna(ESA),with their sizes being the same size,and the maximum transmission distance obtained experimentally is 100 cm,which can be improved by increasing the input *** addition,the gain,directivity,and quality factor of piezoelectric antenna are also *** this paper,traditional antenna parameters are creatively used to analyze the performance of piezoelectric *** research conclusions can provide reliable theoretical basis for realizing LF antenna miniaturization.

关键词： piezoelectric low frequency antenna resonance frequency radiation quality factor antenna miniaturization

Fault diagnosis for gearboxes based on Fourier decomposition method and resonance demodulation

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第5期24卷 404-418页

作者： Shuiguang TONG Zilong FU Zheming TONG Junjie LI Feiyun CONG State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China School of Mechanical Engineering Zhejiang UniversityHangzhou 310027China

Condition monitoring and fault diagnosis of gearboxes play an important role in the maintenance of mechanical *** vibration signal of gearboxes is characterized by complex spectral structure and strong time variability,which brings challenges to fault feature *** address this issue,a new demodulation technique,based on the Fourier decomposition method and resonance demodulation,is proposed to extract fault-related ***,the Fourier decomposition method decomposes the vibration signal into Fourier intrinsic band functions(FIBFs)adaptively in the frequency ***,the original signal is segmented into short-time vectors to construct double-row matrices and the maximum singular value ratio method is employed to estimate the resonance ***,the resonance frequency is used as a criterion to guide the selection of the most relevant FIBF for demodulation ***,for the optimal FIBF,envelope demodulation is conducted to identify the fault characteristic *** main contributions are that the proposed method describes how to obtain the resonance frequency effectively and how to select the optimal FIBF after decomposition in order to extract the fault characteristic *** numerical and experimental studies are conducted to investigate the performance of the proposed *** is demonstrated that the proposed method can effectively demodulate the fault information from the original signal.

关键词： Fourier decomposition method Singular value ratio resonance frequency Envelope demodulation Fault diagnosis

Modeling and Optimal Design of 3 Degrees of Freedom Helmholtz Resonator in Hydraulic System

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2012年第5期25卷 776-783页

作者： GUAN Changbin JIAO Zongxia School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Science and Technology on Aircraft Control Laboratory Beihang UniversityBeijing 100191China

Three degrees of freedom （3-DOF） Helmholtz resonator which consists of three cylindrical necks and cavities connected in series （neck-cavity-neck-cavity-neck-cavity） is suitable to reduce flow pulsation in hydraulic system. A novel lumped parameter model （LPM） of 3-DOF Helmholtz resonator in hydraulic system is developed which considers the viscous friction loss of hy- draulic fluid in the necks. Applying the Newton＇s second law of motion to the equivalent mechanical model of the resonator, closed-form expression of transmission loss and resonance frequency is presented. Based on the LPM, an optimal design method which employs rotate vector optimization method （RVOM） is proposed. The purpose of the optimal design is to search the reso- nator＇s unknown parameters so that its resonance frequencies can coincide with the pump-induced flow pulsation harmonics respectively. The optimal design method is realized to design 3-DOF Helmholtz resonator for a certain type of aviation piston pump hydraulic system. The optimization result shows the feasibility of this method, and the simulation under optimum parame- ters reveals that the LPM can get the same precision as transfer matrix method （TMM）.

关键词： structural optimization vibration analysis hydraulic resonator lumped parameter model rotate vector optimizationmethod transmission loss resonance frequency