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Electromechanical coupling model and analysis of transient behavior for inertial vibrating machines

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Journal of Chongqing University 2004年第2期3卷 43-47页

作者：胡继云 Mechanical and electrical engineering department Henan University of Technology Zhengzhou 450052 P. R. China

A mathematical model of electromechanical coupling system for a planar inertial vibrating machine is built by setting up dynamical equations of discrete systems with a matrix methodology proposed. The substance of the transient behavior of the machine is unveiled by analyzing the results of the computer simulation to the model, and new methods are presented for diminishing the transient amplitude of the vibrating machine and improving the transient behavior. The reliable mathematical model is provided for intelligent control of the transient behavior of the equipment.

关键词： inertial vibrating machine electromechanical coupling matrix method transient behavior

A semi-analytical pressure and rate transient analysis model for inner boundary and propped fractures exhibiting dynamic behavior under long-term production conditions

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Petroleum Science 2024年第4期21卷 2520-2535页

作者： Lin-Song Cheng Chong Cao Quan-Yu Pan Pin Jia Ren-Yi Cao Zhi-Kai Wang Jun-Jie Shi College of Petroleum Engineering China University of Petroleum(Beijing)Beijing102249China Sinopec Petroleum Exploration and Production Research Institute Beijing100083China CNOOC Research Institute Beijing100028China State Key Laboratory of Water Resources Protection and Utilization in Coal Mining Beijing112211China

The loss of hydrocarbon production caused by the dynamic behavior of the inner boundary and propped fractures under long-term production conditions has been widely reported in recent ***,the quantitative relationships for the variations of the inner boundary and propped fractures have not been determined and incorporated in the semi-analytical models for the pressure and rate transient *** work focuses on describing the variations of the inner boundary and propped fractures and capturing the typical characteristics from the pressure transient curves.A generalized semi-analytical model was developed to characterize the dynamic behavior of the inner boundary and propped fractures under long-term production *** pressure-dependent length shrinkage coefficients,which quantify the length changes of the inner zone and propped fractures,are modified and incorporated into this multi-zone semi-analytical *** simultaneous numerical iterations and numerical inversions in Laplace and real-time space,the transient solutions to pressure and rate behavior are determined in just a few *** dynamic behavior of the inner boundary and propped fractures on transient pressure curves is divided into five periods:fracture bilinear flow(FR1),dynamic PFs flow(FR2),inner-area linear flow(FR3),dynamic inner boundary flow(FR4),and outer-area dominated linear flow(FR5).The early hump during FR2 period and a positive upward shift during FR4period are captured on the log-log pressure transient curves,reflecting the dynamic behavior of the inner boundary and propped fractures during the long-term production *** transient pressure behavior will exhibit greater positive upward trend and the flow rate will be lower with the shrinkage of the inner *** pressure derivative curve will be upward earlier as the inner boundary shrinks more *** lower permeability caused by the closure of un-propped fractures in the inner zone results in gr

关键词： Semi-analytical model Length shrinkage Dynamic behavior Boundary changes transient behavior

A multiphysics model for studying transient crevice corrosion of stainless steel

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Journal of Materials Science & Technology 2021年第1期60卷 186-196页

作者： Jiawei Ding Haitao Wang En-Hou Han CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026China

The transient crevice corrosion behavior of 304 stainless steel in NaCl solution has been investigated by a multiphysics coupling *** model considers local electrochemical reactions,transport of diffe rent species,and homogeneous *** moving mesh method is used to obtain the geometrical change of the crevice wall with time due to *** level set method is employed to quantitatively describe the influence of the precipitation process on electrochemical *** transient crevice corrosion morphology,potential and current distributions,and pH and chloride ion concentration distributions are obtained by *** effect of crevice geometry factors on the corrosion process is also *** simulation results are in good agreement with the experiments,showing that the model has high reliability.

关键词： Stainless steel Crevice corrosion Simulation Multiphysics transient behavior

Sigma-delta modulator modeling analysis and design

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Journal of Semiconductors 2010年第9期31卷 79-83页

作者：葛彬杰王新安张兴冯晓星汪清勤 Key Laboratory of Integrated Microsystem Science & Engineering Applications Shenzhen Graduate School of Peking University

This paper introduces a new method for SC sigma-delta modulator *** studies the integrator＇s different equivalent circuits in the integrating and sampling *** model uses the OP-AMP input pair＇s tail current（I_0） and overdrive voltage（v_（on）） as *** modulator＇s static and dynamic errors are analyzed.A group of optimized I0 and von for maximum SNR and power x area ratio can be obtained through this *** examples, a MASH21 modulator for digital audio and a second order modulator for RFID baseband are implemented and tested, and they can achieve 91 dB and 72 dB respectively,which verifies the modeling and design criteria.

关键词： sigma-delta modeling transient behavior optimization

Experimental Study on a Centrifugal Pump with an Open Impeller during Startup Period

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Journal of Thermal Science 2013年第1期22卷 1-6页

作者： Yuliang Zhang Zuchao Zhu Yingzi Jin Baoling Cui Yi Li Huashu Dou The State Key Lab of Fluid Power Transmission and Control Zhejiang University The Province Key Lab of Fluid Transmission Technology Zhejiang Sci-Tech University

transient performance of fluid machinery during transient operating periods, such as startup and stopping, has been drawn more attentions recently due to the growing engineering needs. In this paper, the transient behavior of a prototype centrifugal pump with an open impeller during rapid startup period is studied experimentally. The variations of the rotational speed, flow rate, head, and shaft power during rapid startup period are recorded in ex- periments at different discharge valve openings. In addition, the non-dimensional flow rate and head are also used to analyze the transient behavior. The research result shows that the rise characteristic of the rotational speed is not basically changed by working points, while mainly depends on the startnp characteristics of the driving motor. Compared with the rapid rise of the rotational speed, the flow rate rises slowly in the initial stage of startup. Moreover, the flow rate lags behind the rotational speed to rise to final stable value, and the delay becomes more severe with the increase of the discharge valve opening. The shaft power impact phenomenon generally exists in the process of startup. The non-dimensional analysis shows that the non-dimensional head is very high at the very beginning of startup, and quickly falls to the minimum, then gradually rises to final stable value, while the non-dimensional flow rate always shows the rise tendency during whole startup period. In conclusion, it is found from the non-dimensional results that the quasi-steady analysis is unable to accurately assess the transient flow during startup period.

关键词： centrifugal pump open impeller startup experimental study transient behavior

transient Analysis of Bandwidth Allocation Strategies in Broadband ISDN

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Wuhan University Journal of Natural Sciences 1996年第1期1卷 76-80页

作者： Yan Puliu Hou Jiechang (College of Electronic Information, Wuhan University, Wuhan 430072,China) College of Electronic Information Wuhan University Wuhan China

We study the transient behavior of B-ISDN bandwidth allocation strategies in tills paper. First, we present the united state transition equations and obtain the steady-state probability distribution vector by the matrixgeometric solution method. Second, we treat the problem in a uniform way that establishing the coupled differential equations describing the dynamic flow process of B-ISDN channel with the steady state probability as its initial condition and solve it numerically based on the fourth-order Runge-kutta procedure which allows a good balance between computing time and accuracy. Finally, experiment results and discussion are given to illustrate the effectes of the method presented in this paper and show that the idea and analysis way can be extended to all dynamic traffic controlling and management in B-ISDN systems.

关键词： B-ISDN transient behavior bandwidth allocation

AVAILABILITY ANALYSIS OF THE QUEUEING SYSTEM GI/PH/I WITH SERVER BREAKDOWNS

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Journal of Systems Science & Complexity 2003年第2期16卷 177-183页

作者： YUANXueming LIWei InstituteofAppliedMathematics ChineseAcademyofSciencesBeijing100080China//SingaporeInstituteofManufacturingTechnology71NanyangDriveSingapore638075 InstituteofAppliedMathematics ChineseAcademyofSciencesBeijing100080China//DepartmentofElectricalEngineeringandComputerScienceUniversityofToledoToledoOH43606USA

In the existing literature of Repairable Queueing Systems (RQS), i.e., queueing systems with server breakdowns, it is almost all assumed that interarrival times of successive customers are independent, identically exponentially distributed. In this paper, we deal with more generic system GI/PH/1 with server's exponential uptime and phase-type repair time. With matrix analysis theory, we establish the equilibrium condition and the characteristics of the system, derive the transient and stationary availability behavior of the system.

关键词： repairable queueing systems transient behavior stationary behavior markovrenewal processes

一种非线性光电反馈光学双稳装置的瞬态特性研究

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东南大学学报(自然科学版) 1988年第6期 130-134页

作者：崔一平杨正名魏先任南京工学院电子工程系

自从Smith等人于1977年提出了“混合型”双稳装置以来,许多文献对此方案进行了改进。文献[8],[9]对线性反馈混合型光学双稳态的特性作了详细分析。此后李淳飞等人报道了一种非线性光电反馈的光学双稳装置的实验结果。随后他们又引入了... 详细信息

自从Smith等人于1977年提出了“混合型”双稳装置以来,许多文献对此方案进行了改进。文献[8],[9]对线性反馈混合型光学双稳态的特性作了详细分析。此后李淳飞等人报道了一种非线性光电反馈的光学双稳装置的实验结果。随后他们又引入了静态稳定度来分析双稳态的稳定性。本文对文献[10]所提出的非线性反馈双稳态的开关时间

关键词： nonlinear optoelectric feedback hybrid optical bistability transient behavior critical slowing down.