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Identification of Steady state and transient state

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Journal of Shanghai Jiaotong university(Science) 2024年第2期29卷 261-270页

作者：于生李向舜 School of Automation Wuhan University of TechnologyWuhan 430070China

Identification of steady state and transient state plays an important role in modeling,control,optimiza-tion,and fault detection of industrial *** existing methods for state identification are not satisfactory in practical applications due to problems of ideal hypothesis,too many parameters,and poor *** this paper,a novel state identification approach is *** problem of state identification is transformed into finding the noise band of differential *** practical application,automatic selection of noise band amplitude is proposed to make the method convenient to be *** of gross errors,low signal-to-noise ratio and online identification are *** comparison with other two methods shows that the proposed method has better identification *** and experiments also prove the effectiveness and practicability of the proposed method.

关键词： state identification steady state transient state noise band differential signal

Research on The transient state Fault Diagnosis of Asynchronous Motors Based on Error Theory

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Research on The Transient State Fault Diagnosis of Asynchron...

B-COPNA resin formation from ethylene tar light fractions:Process development and mechanical exploration by molecular simulation

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作者： Zefeng Sun Kai Li Feng Yuan Heilongjiang Electric Power Co.Ltd State Grid

During the normal operation of the asynchronous motor driven system,due to the requirements of commutation,inversion,and other driving factors,as well as the influence of control factors such as starting,stopping,and speed-regulating,the motor will undergo a certain period of transient *** the transient state,the stator current and voltage of the motor will produce amplitude distortion,the values of which are different from those in the steady *** the transient state lasts for a short time,this unpredictable and uncontrolled instantaneous distortion is likely to cause *** term and frequent overloads are easily to cause faults in the motor driven *** response to the above issues,this article takes a type of thyristor driven asynchronous motor system as the research object,takes the stator voltage and current during the soft start state as the characteristic parameters in the transient state,and proposes a novel fault diagnosis strategy based on the procedure of error *** numerical calculation and experimental research based on such new method prove this strategy effective.

关键词： Asynchronous motors transient state Fault diagnosis Error theory

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Chinese Journal of Chemical Engineering 2024年第6期70卷 118-129页

作者： Hongyan Shen Lingrui Cui Xingguo Wei Yuanqin Zhang Lian Cen Jun Xu Fahai Cao Engineering Research Center of Large Scale Reactor East China University of Science and TechnologyShanghai 200237China

An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical *** the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw *** such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling pointstate of ETLF and crosslinking *** was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking *** addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed *** corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular ***,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.

关键词： Ethylene tar Crosslinking COPNA resin Molecular simulation transient state

A Novel Approach for Evaluating Nonstationary Response of Dynamic Systems to Stochastic Excitation

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Journal of Ocean University of China 2020年第4期19卷 781-789页

作者： CAO Qianying HU Sau-Lon James LI Hewenxuan College of Engineering Ocean University of ChinaQingdao 266100China Department of Ocean Engineering University of Rhode IslandNarragansettRI 02882USA College of Engineering University of Rhode IslandKingstonRI 02881USA

The transient state of a dynamic system,such as offshore structures,to random excitation is always *** studies have contributed to evaluating response covariances at the transient state of a linear multi-degree-of-freedom(MDOF)system to random excitations,but a closed-form solution was not available unless the excitation was assumed to be a physically unrealizable white noise *** study derives explicit,closed-form solutions for the response covariances at the transient state by using a pole-residue(PR)approach operated in the Laplace domain when the excitations are assumed to be stationary random processes described by physically realizable spectral density *** using the PR method,we can analytically solve the triple integral in evaluating the nonstationary response *** this approach uses the poles and residues of system transfer functions,rather than the conventional mode superposition technique,the method is applicable to MDOF systems with non-classical damping *** application of the proposed method is demonstrated for multi-story shear buildings to stochastic ground acceleration characterized by the Kanai–Tajimi spectral density function model,and a numerical example is provided to illustrate the detailed *** numerical integrations are required for computing the response covariances as the exact closed-form solution has been *** correctness of the proposed method is numerically verified by Monte Carlo simulations.

关键词： linear systems transient state nonstationary response pole residue

THE DECOMPOSITION OF state SPACE FOR MARKOV CHAIN IN RANDOM ENVIRONMENT

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Acta Mathematica Scientia 2005年第3期25卷 555-568页

作者：胡迪鹤 School of Mathematics and Statistics Wuhan University

This paper is a continuation of [8] and [9]. The author obtains the decomposition of state space X of an Markov chain in random environment by making use of the results in [8] and [9], gives three examples, random walk in random environment, renewal process in random environment and queue process in random environment, and obtains the decompositions of the state spaces of these three special examples.

关键词： Markov chain in random environment recurrent state transient state decomposition

THE CLASSIFICATION AND PERIOD OF stateS FOR MARKOV CHAIN IN RANDOM ENVIRONMENT

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Acta Mathematica Scientia 2005年第1期25卷 23-29页

作者：胡迪鹤 College of Mathematics and Statistics Wuhan University Wuhan 430072 China

This paper is a continuation of [8]. In Section 1, three kinds of communication are introdnced for two states and the relations among them are investigated. In Section 2, two kinds of period of a state are introdnced and it is obtained that the period is a 'class property',i.e. two states x and y belong to same class implies the period of x is equal to the period of y.

关键词： Markov chain in random environment recurrent state transient state period

Application of DC component to select fault branch in arc suppression coil grounding system

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Journal of Coal Science & Engineering(China) 2013年第3期19卷 396-401页

作者： Zhi-Jie WANG Yan-Wen WANG School of Mechanical Electrical and Information Engineering China University of Mining and Technology (Beijing) Beijing 100083 China

When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.

关键词： DC component arc suppression coil fault line selection transient state

Finite element analysis of temperature distribution of polycrystalline silicon thin film transistors under self-heating stress

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Frontiers of Electrical and Electronic Engineering in China 2009年第2期4卷 227-233页

作者： Huaisheng WANG Mingxiang WANG Zhenyu YANG Department of Microelectronics Soochow UniversitySuzhou 215021China

The temperature distribution of typical n-type polycrystalline silicon thin film transistors under selfheating(SH)stress is studied by finite element *** both steady-state and transient thermal simulation,the influence of device power density,substrate material,and channel width on device temperature distribution is *** study is helpful to understand the mechanism of SH degradation,and to effectively alleviate the SH effect in device operation.

关键词： finite element analysis(FEA) temperature distribution thin film transistors self-heating steady-state transient state

The Classification of states for Markov Chain in Random Environments and m-irreducible

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Wuhan University Journal of Natural Sciences 2007年第3期12卷 402-406页

作者： WANG Weigang HU Dihe School of Mathematics and Statistics Wuhan UniversityWuhan 430072 Hubei China School of Mathematics and Statistics Yunnan UniversityKunming 650091 Yunnan China

First of all, we introduces the concept of m-irreducible of Markov chain in random environment. Then under the condition of m-irreducible, the relationship of recurrent and positive recurrent between two states is studied. We also give several conditions that can imply a state is recurrent and positive recurrent. And then the period of a state is discussed and we obtained that under the condition of m-irreducible, for any two states in x, they have the same period.

关键词： Markov chain in random environment m-irreducible recurrent stat transient state positive recurrent