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A new ground impedance measuring element for digital distance relaying of long parallel lines in high fault resistance conditions

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INTERNATIONAL TRANSACTIONS ON ELECTRICAL ENERGY SYSTEMS 2016年第7期26卷 1376-1396页

作者： Abdollahzadeh, Hamed Mozafari, Babak Jazaeri, Mostafa Islamic Azad Univ Sci & Res Branch Dept Elect Engn Tehran Iran Univ Semnan Dept Elect Engn Semnan Iran

Ground impedance measuring elements (ground elements), which are responsible for removing single-phase-to-ground faults in distance relays, are highly prone to underreach when facing a significant resistance in the fault path. This paper proposes a new ground element with ensured dependability in high fault resistance conditions for the first-zone digital distance relaying of parallel lines. The proposed ground element functions on the basis of the fault distance and fault resistance it estimates, online during the faults, through the equation derived from the voltages and currents of the distributed-parameters line model. Hence, it will be particularly applicable to the parallel lines of long length in which the distributed parameters effect is significant. The proposed element requires only the data acquired at the relaying location. Further, its function is independent of the structural configuration of the system. Unlike conventional ground elements, the proposed element preserves its security in case of irrelevant-circuit as well as external faults. Simulation studies conducted in MATLAB and PSCAD/EMTDC examine the proposed ground element in a variety of influencing situations, and the results reveal that it accurately trips the faults in the first zone with no incidence of underreach in case of high resistance faults. The accuracy of the proposed element is over 99.4% and its tripping time within 0.3-1.3cycles. Copyright (c) 2015 John Wiley & Sons, Ltd.

关键词： Parallel lines High-resistance faults Distance relays Ground elements Fault distance distributed parameters

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High-Voltage Cable Buffer Layer Ablation Fault Identification Based on Artificial Intelligence and Frequency Domain Impedance Spectroscopy

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SENSORS 2024年第10期24卷 3067页

作者： Liu, Jiajun Ma, Mingchao Liu, Xin Xu, Haokun Xian Univ Technol Sch Elect Engn Xian 710054 Peoples R China

In recent years, the occurrence of high-voltage cable buffer layer ablation faults has become frequent, posing a serious threat to the safe and stable operation of cables. Failure to promptly detect and address such faults may lead to cable breakdowns, impacting the normal operation of the power system. To overcome the limitations of existing methods for identifying buffer layer ablation faults in high-voltage cables, a method for identifying buffer layer ablation faults based on frequency domain impedance spectroscopy and artificial intelligence is proposed. Firstly, based on the cable distributed parameter model and frequency domain impedance spectroscopy, a mathematical model of the input impedance of a cable containing buffer layer ablation faults is derived. Through a simulation, the input impedance spectroscopy at the first end of the cables under normal conditions, buffer layer ablation, local aging, and inductive faults is performed, enabling the identification of inductive and capacitive faults through a comparative analysis. Secondly, the frequency domain amplitude spectroscopy of the buffer layer ablation and local aging faults are used as datasets and are input into a neural network model for training and validation to identify buffer layer ablation and local aging faults. Finally, using multiple evaluation metrics to assess the neural network model validates the superiority of the MLP neural network in cable fault identification models and experimentally confirms the effectiveness of the proposed method.

关键词： buffer layer ablation artificial intelligence distributed parameters fault identification

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Mathematical modelling of wheat drying by fractional order and assessment of transport properties

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CANADIAN JOURNAL OF CHEMICAL ENGINEERING 2024年第2期102卷 996-1006页

作者： Aranha, Ana Caroline Raimundini Ferrari, Andressa Lopes Bissaro, Camila Andressa Matias, Gustavo de Souza Defendi, Rafael Oliveira Paschoal, Sirlei Marques Jorge, Luiz Mario de Matos State Univ Maringa UEM Chem Engn Grad Program PEQ 5790 Colombo AveBlock E-46 BR-87020900 Maringa Brazil Fed Technol Univ Parana UTFPR Chem Engn Grad Program PPGEQ AP Apucarana Brazil State Univ Parana UNESPAR Ind Engn Dept Paranagua Brazil

The purpose of this study is to evaluate both the temperature and the initial moisture content of the material in mathematical models of drying. For this, empirical lumped parameter models were fitted based on experimental data of moisture over time. Furthermore, a new semi-empirical drying kinetics model was applied. This model was developed using the generalization of arbitrary order of the Lewis equation obtained through the Laplace transform. After performing the fit, the fractional order model for drying wheat seeds as a temperature function was generalized. distributed parameter models were also fitted to evaluate the influence of initial moisture content on drying kinetics and to estimate the moisture profile along the position inside the seed. It was verified that the fractional order model presented statistical results similar to models with a higher number of constants, being used to generalize the kinetic drying model for the three wheat cultivars. Generalized models showed better fits for the 3 cultivars with first-degree function, and the maximum global deviation was 10%, 15%, and 20% for the cultivars BRS-Atoba, BRS-Jacana, and BRS-Sanhaco, respectively. In addition, the distribution of moisture content inside the seed was verified by the distributed parameter model, which predicted the experimental data with an overall deviation of around 10%.

关键词： distributed parameters drying empirical models fractional order lumped parameters

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A current differential relay for a 1000-kV UHV transmission line

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IEEE TRANSACTIONS ON POWER DELIVERY 2007年第3期22卷 1392-1399页

作者： Xu, Z. Y. Du, Z. Q. Ran, L. Wu, Y. K. Yang, Q. X. He, J. L. Tsing Hua Univ Dept Elect Engn & Elect Beijing 100084 Peoples R China Beijing Sifang Automat Co Ltd Beijing 100085 Peoples R China Univ Durham Sch Engn Sci Labs Durham DH1 3LE England Tianjin Univ Dept Elect Engn Tianjin 300072 Peoples R China

This paper describes the principle of a new current differential relay developed for a 1000-kV UHV transmission line that is being constructed in China. The distributed capacitive current along the relatively long overhead line will have a significant effect on the relay performance and should be taken into account in the relay principle. The study results in a new current differential relay based on the steady state transmission line equations, in which the distributed capacitive current is inherently represented. Analysis is carried out for different practical situations where shunt reactors or series capacitors are present in the system for compensation. Laboratory tests show that the relay principle developed in this study can be used as a main protection scheme for the 1000-kV UHV transmission line.

关键词： 1000-kV UHV transmission line current differential relay distributed parameters transmission line equations

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OPTIMAL OPEN CLOSED-LOOP CONTROL OF A RAYLEIGH BEAM

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OPTIMAL CONTROL APPLICATIONS & METHODS 1992年第3期13卷 247-253页

作者： ESFANDIARI, RS SADEK, IS UNIV N CAROLINA DEPT MATH SCIWILMINGTONNC 28403

optimal open/closed-loop control of a Rayleigh beam relative to a specified performance measure is investigated. A method to suppress the undesired transient beam vibrations is proposed and utilized to obtain numerical results for different problem parameters. With the assumption of a prescribed closed-loop control law, the Fourier-type open-loop optimal control law is derived in closed form through minimization of the performance measure via a calculus-of-variations technique. Numerical results presented in graphical form indicate that a feedback control mechanism may be effectively utilized in the presence of an open-loop control.

关键词： OPTIMAL OPEN CLOSED-LOOP CONTROL PERFORMANCE MEASURE RAYLEIGH BEAM distributed parameters FOURIER-TYPE OPEN-LOOP CONTROL

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Investigation of the synergism on distribution parameters of micro dimples in partially textured thrust pad bearing

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY 2023年第3期237卷 484-497页

作者： He, Yuyang Ji, Jinghu Fu, Yonghong Deng, Zhiwen Yang, Jie Jiangsu Univ Sch Mech Engn Zhenjiang 212013 Jiangsu Peoples R China

Partially surface texturing is a promising technology to improve the performance of thrust pad bearing. Moreover, how to design the distribution parameters of local textures is a crucial issue of the amelioration of lubrication and anti-friction. Hence, the synergistic effect of micro dimples' distribution parameters was systematically investigated by numerical and experimental approaches. The textured region area ratio (TRAR) was defined to analyze the synergy of radial and circumferential parameters. Then, a series of frictional tests were conducted with different positions and proportions. The results showed that the CPP and RPP directly determined the efficacy of the 'equivalent Rayleigh step' which could enhance the cumulative response of hydrodynamic lubrication. Meanwhile, there was an optimal TRAR (about 0.8) according to the favorable fitting curve with R Square (R-2) being 0.9013. And circumferential proportion parameter (CPP) and radial proportion parameter (RPP) exhibit an interactive relationship which was dependent on the optimal TRAR. On the other hand, for generating the 'inlet roughness' and 'open pocket', the circumferential location parameter (CLP) of local textures needed to keep close to the inlet without consideration of the radial location parameter (RLP) due to the negligible influence.

关键词： Thrust pad bearing partially textured surface synergism distributed parameters

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Modelling of liquid flat-plate solar collector operation in transient states

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY 2011年第A1期225卷 53-62页

作者： Zima, W. Dziewa, P. Cracow Univ Technol Dept Thermal Power Engn PL-31864 Krakow Poland

The article presents a one-dimensional mathematical model for simulating the transient processes which occur in liquid flat-plate solar collectors. The proposed method considers a collector model with distributed parameters. In the model, the boundary conditions can be time dependent. The proposed model is based on solving equations which describe the energy conservation for the glass cover, air gap between cover and absorber, absorber, working fluid, and insulation. The differential equations derived were solved using the implicit finite-difference method in an iterative scheme. All thermo-physical properties of the fluid, absorber and air gap are computed in real time. The time-spatial distributions of heat transfer coefficients are also computed in the on-line mode. In order to experimentally verify the proposed method, a test bench was built and measurements were carried out. Comparing the measurement results of the transient fluid temperature at the collector outlet with computational results, satisfactory convergence is found. The proposed method is appropriate for the verification of the effectiveness of various absorbers and their surface coatings, without the need to carry out research on existing collectors. It allows the influence of fluid mass flowrate on the collector performance to be analysed and collector time constant to be determined. The presented model is suitable for collectors working in a parallel or in a serpentine tube arrangement with single or double covers.

关键词： solar collector mathematical model distributed parameters transient state experimental verification

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CHAOS SOLITONS & FRACTALS 2024年 181卷

作者： Mahfoudi, Narimene Bouguerra, Abdesselam Triki, Houria Azzouzi, Faical Biswas, Anjan Yildirim, Yakup Alshomrani, Ali Saleh Univ Souk Ahras Dept Matter Sci Lab Phys Matter & Radiat LPMR POB 1553 Souk Ahras 41000 Algeria Badji Mokhtar Univ Fac Sci Dept Phys Radiat Phys Lab POB 12 Annaba 23000 Algeria Grambling State Univ Dept Math & Phys Grambling LA 71245 USA King Abdulaziz Univ Ctr Modern Math Sci & their Applicat CMMSA Dept Math Math Modeling & Appl Computat MMAC Res Grp Jeddah 21589 Saudi Arabia Sefako Makgatho Hlth Sci Univ Dept Math & Appl Math ZA-0204 Pretoria South Africa Dunarea de Jos Univ Galati Cross Border Fac Humanities Econ & Engn Dept Appl Sci 111 Domneasca St Galati 800201 Romania Biruni Univ Dept Comp Engn TR-34010 Istanbul Turkiye Near East Univ Math Res Ctr Nicosia Cyprus

This study investigates the dynamics of ultrashort light pulses in an inhomogeneous optical medium exhibiting all orders of nonlinearity up to the ninth order. The research focuses on exploring the existence and properties of self -similar solitons while varying cubic, quintic, septic, and nonic nonlinearities, group velocity dispersion, and loss or gain. It is found that the transmission system supports the existence of novel types of self -similar bright and dark pulses in the presence of various physical processes. Importantly, these self -similar localized waves exhibit a linear chirp, a crucial factor for achieving effective pulse amplification or compression. Based on the chirp property, the dynamical behaviors of these self -similar waveforms are discussed in a periodically distributed amplification system. The findings highlight that the shape and dynamics of these chirped selfsimilar pulses can be precisely controlled by selecting appropriate profiles for gain or loss, nonlinearity, and dispersion. Additionally, the research numerically discusses the interaction dynamics between two and three adjacent solitons.

关键词： Self-similar solitons Cubic-quintic-septic-nonic medium distributed parameters

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distributed Parameter Modelling of Cutout 2-DOF Cantilevered Piezo-Magneto-Elastic Energy Harvester

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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS 2018年第6期27卷 1160-1170页

作者： Krishnasamy, M. Upadrashta, Deepesh Yang, Yaowen Lenka, Trupti Ranjan Natl Inst Technol Dept Elect & Commun Engn Microelect & VLSI Design Grp Silchar 788010 Assam India Kalasalingam Acad Res & Educ Sch Elect & Elect Technol Krishnankovil 626126 India Nanyang Technol Univ Sch Civil & Environm Engn Singapore 639798 Singapore

Energy harvesters play the vital role in replacing/recharging the electrochemical batteries in low-power electronic devices. Non-linear piezoelectric energy harvesters generate electrical power from broadband frequency spectrum using ambient vibrational sources. Non-linear cutout 2- degree of freedom (DOF) piezo-magneto-elastic (PME) energy harvester has been proposed to enhance the bandwidth where two close resonant peaks are achieved using magnetic interaction. In this paper, the novel theoretical distributed parametric model of cutout 2-DOF energy harvester is presented which can predict the dynamic behavior of the linear (without magnetic force) and non-linear monostable configurations accurately. The closed-form analytical solutions are derived for the harvested electrical responses and displacements using forcing function, forward and backward coupling factors through Extended Hamilton principle, Galerkin approach, and Euler-Lagrange equations. Specifically, the static displacements and tuned resonant frequencies are obtained as a function of the initial distance between the two magnets in attractive and repulsive configurations. The theoretical findings are validated with COMSOL simulation results and experimental data. The comparison among theoretical, finite-element, and experimental results show that the developed model of cutout 2-DOF piezo-magneto-elastic energy harvester can accurately predict the response for linear and non-linear monostable configurations.

关键词： distributed parameters energy harvester magnetic force multi-mode model piezoelectric

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Thermal analysis of PV/T evaporator of a solar-assisted heat pump

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INTERNATIONAL JOURNAL OF ENERGY RESEARCH 2007年第5期31卷 525-545页

作者： Ji, He Liu, Keliang Chow, Tin-Tai Pei, Gang He, Hanfeng Univ Sci & Technol China Dept Thermal Sci & Energy Engn Anhua 230026 Peoples R China City Univ Hong Kong Div Bldg Sci & Technol Hong Kong Hong Kong Peoples R China

The performance of photovoltaic/thermal (PV/T) solar collector had been studied theoretically and experimentally for some years. Air and water streams were used as the heat carriers for space heating or services hot water systems. The cooling effect allows the PV module to work at lower temperature and its PV efficiency is therefore improved. However, such an advantage diminishes when the solar irradiance is high. To improve the situation a new type of PV/T collector is proposed. It works as the evaporator of a heat pump, in that refrigerant evaporates in the tubing at the back of the flat-plate collector and the PV module is adhered to the front surface. Mathematical models were developed to simulate the complex energy conversion processes. Numerical analysis was then performed based on the distributed parameters approach. An experimental rig was also built to test its real performance. Our results showed that the PV/T evaporator had an overall efficiency in the range of 0.64-0.87, thermal efficiency 0.53-0.64 and PV efficiency 0.124-0.135. The simulation results were found in good agreement with the experiment measurements. Copyright (c) 2006 John Wiley & Sons, Ltd.

关键词： PV/T evaporator distributed parameters heat and electricity conversion solar-assisted heat pump (SAHP)

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