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1st IEEE Ukraine Conference on Electrical and Computer Engineering (UKRCON)

作者： Mokin, Oleksandr Mokin, Borys Kryvonis, Oleksandr Vinnytsia Natl Tech Univ Dept Renewable Energy & Transport Elect Syst & Co Vinnytsia Ukraine

ISBN: (纸本)9781509030064

The work offers synthesized mathematical models for one class of variable-parameter electromechanical systems which include electric drives of cranes and shaft skip hoists. The mathematical models are differential equations with variable parameters depending on variations of reduced moments of inertia and load moments of drive electric motors in the course of load lifting and lowering.

关键词： crane shaft skip hoist inertia moment load moment DC drive electric motor AC drive electric motor mathematical model differential equation variable parameters

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Existence of global BV solutions to a model of reacting Euler fluid with variable thermodynamics parameters

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JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS 2018年第1期457卷 890-921页

作者： Hu, Kai Southwest Univ Sch Math & Stat Chongqing 400715 Peoples R China

We investigate the Cauchy problems of Euler equations coupled with chemical reaction equation. The specific heat and adiabatic parameters of compressible fluid are introduced as functions with respect to reactant mass fraction in this paper. By means of fractional step wave-front tracking scheme, we derive the existence of global BV solution, and verify that it is indeed an entropy weak solution. This system is also regarded as balance law with resonant characteristic fields. Hence some decay condition is imposed on the source term, in order to handle the damping effect. (c) 2017 Published by Elsevier Inc.

关键词： Reacting Euler fluid Balance law Cauchy problem variable parameters Front tracking method

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A creep constitutive model with variable parameters for thenardite

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ENVIRONMENTAL EARTH SCIENCES 2016年第11期75卷 1页

作者： Wang, Junbao Liu, Xinrong Song, Zhanping Guo, Jianqiang Zhang, Qianqian Xian Univ Architecture & Technol Sch Civil Engn Xian 710055 Peoples R China Chongqing Univ Sch Civil Engn Chongqing 400045 Peoples R China Guizhou Univ Sch Civil Engn Guiyang 550003 Peoples R China

Results from the triaxial creep tests indicate that the relationship between steady creep rate of thenardite and deviatoric stress can be described with the Heard model. By combining the Kelvin model which reflects the primary creep property of rock with the Heard steady creep model, a Kelvin-Heard (K-H) creep model is constructed. However, the predicted curves from the K-H model are not in good agreement with the creep test data of thenardite. To improve the prediction precision, it is assumed that the viscosity coefficient of thenardite increases over time in primary creep stage, and an improved K-H model is proposed. Compared with the K-H model, the improved K-H model can more precisely describe the creep behavior of thenardite under a certain stress state. However, each of its parameters G, eta(infinity), a and b has different values under different deviatoric stress levels. These four parameters all decrease with the increase in deviatoric stress, which is considered to establish an improved K-H model with variable parameters for thenardite finally. Comparison with the test data shows that this model can precisely predict the creep behavior of thenardite when 25 MPa <= sigma(1) - sigma(3) <= 40 MPa.

关键词： Thenardite Creep model variable parameters Prediction

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Chaotic hash function based on circular shifts with variable parameters

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CHAOS SOLITONS & FRACTALS 2016年 91卷 639-648页

作者： Li, Yantao Li, Xiang Southwest Univ Coll Comp & Informat Sci Chongqing 400715 Peoples R China Nanjing Univ State Key Lab Novel Software Technol Nanjing 210023 Jiangsu Peoples R China

We propose a chaotic hash algorithm based on circular shifts with variable parameters in this paper. We exploit piecewise linear chaotic map and one-way coupled map lattice to produce initial values and variable parameters. Circular shifts are introduced to improve the randomness of hash values. We evaluate the proposed hash algorithm in terms of distribution of the hash value, sensitivity of the hash value to slight modifications of the original message and secret keys, confusion and diffusion properties, robustness against birthday and meet-in-the-middle attacks, collision tests, analysis of speed, randomness tests, flexibility, computational complexity, and the results demonstrate that the proposed algorithm has strong security strength. Compared with the existing chaotic hash algorithms, our algorithm shows moderate statistical performance, better speed, randomness tests, and flexibility. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Chaos Hash function variable parameters Piecewise linear chaotic map One-way coupled map lattice

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Chaotic hash function based on the dynamic S-Box with variable parameters

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NONLINEAR DYNAMICS 2016年第4期84卷 2387-2402页

作者： Li, Yantao Ge, Guangfu Xia, Dawen Southwest Univ Coll Comp & Informat Sci Chongqing 400715 Peoples R China Guizhou Minzu Univ Sch Informat Engn Guiyang 550025 Peoples R China

We present a chaotic hash function based on the dynamic S-Box with variable parameters in this paper. More specifically, we first exploit the piecewise linear chaotic map to obtain four initial buffers and an initial hash value. Then, we divide a randomly chosen message into message blocks and assign the four buffers and current message block to a transfer function to produce variable parameters and initial values of the PWLCM and logistic map for constructing a dynamic S-Box, which is then used for updating the four buffers. After all the message blocks are processed, the final hash value is generated by cascading the buffers and then applying XOR operation with the last hash value. Finally, we conduct performance evaluation on the proposed hash algorithm in terms of sensitivity, confusion and diffusion properties, collision resistances, speed analysis, randomness tests, and comparison with other algorithms, and the results demonstrate that the proposed algorithm has good statistical properties, strong collision resistances and better performance compared with other schemes.

关键词： Chaos Hash function Dynamic S-Box Piecewise linear chaotic map variable parameters

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System Frequency Control of variable Speed Wind Turbines with variable Controller parameters

System Frequency Control of Variable Speed Wind Turbines wit...

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International Conference on Life System Modeling and Simulation (LSMS) / International Conference on Intelligent Computing for Sustainable Energy and Environment (ICSEE)

作者： Xu, Guoyi Zhu, Chen Yang, Libin Li, Chunlai Yang, Jun Bi, Tianshu North China Elect Power Univ State Key Lab Alternate Elect Power Syst Renewabl Beijing Peoples R China QingHai Prov Key Lab Photovolta Gird Connected Po Xining Qinghai Peoples R China

ISBN: (纸本)9789811063640;9789811063633

System operators are require wind power plants to provide system frequency control to secure safe operation of power systems. This paper first discussed the available amount of kinetic energy from wind turbines which could be released to provide extra power, minimum rotor speed of wind turbines operate at different condition to provide system frequency control is defined. The strategy to determine the wind turbine frequency controller parameter values is proposed, which will release all the available kinetic energy to provide system frequency support, this strategy also make sure the wind turbine rotor speed drop during frequency support is within the limited range, which ensure the stable operation of the turbine. The proposed strategy is tested by simulations carried out with Matlab/Simulink, which demonstrated the improvements on wind turbine operation and system frequency control effect.

关键词： Wind power Kinetic energy Minimum rotor speed variable parameters

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Optimal parameters of the heap leaching of oxidized nickel ores by the box-wilson steep-ascent method. Part 1

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METALLURGIST 2024年第6期68卷 913-921页

作者： Gavrilov, Aleksey Serheyevich Krasheninin, Aleksey Gennadievich Petrova, Sofia Aleksandrovna Belozerova, Anastasia Anatolievna Reutov, Dmitrii Sergeevich Russian Acad Sci Inst Met Ural Branch Ekaterinburg Russia

We study the material composition of a ferromagnesian oxidized nickel ore of the Serov deposit. According to the results of chemical analysis, it was found that the studied ore is poor in the nickel content. Note that magnesium and iron are present in the ore as macroimpurities. The main nickel-containing minerals are lizardite and clinochlore;smaller amounts of nickel are contained in talc. To determine the optimal technological parameters of heap leaching and reveal their correlation dependences, we use the mathematical method of data processing, namely, the Box-Wilson steep ascent method. Based on the results of leaching, we compute the values of the efficiency criterion and the variance of the efficiency criterion and deduce a regression equation for the description of the process of leaching. The adequacy of the regression equation is established by using the Fisher *** results of mathematical processing of the experimental data show that the concentration of sulfuric acid in the solution, the pause between irrigations, and the specific consumption of the leaching solution exert a significant effect on the efficiency of leaching in the stage of nickel extraction from 0-30%.On the basis of computed values of the efficiency criterion, we determine the values of variable parameters for the second stage of determination of the optimal conditions of leaching guaranteeing the efficient ore opening in the stage of nickel extraction up to 30%.

关键词： Heap leaching Nickel ores Nickel extraction variable parameters Ore stripping 669.243.37

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Economic Design of the variable parameters X over bar Control Chart with a Corrected A&L Switching Rule

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QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL 2014年第2期30卷 235-246页

作者： Guo, Zhi-Fang Cheng, Long-Sheng Lu, Zu-Di Taiyuan Univ Sci & Technol Sch Econ & Management Taiyuan Peoples R China Nanjing Univ Sci & Technol Sch Econ & Management Nanjing Jiangsu Peoples R China Univ Adelaide Sch Math Sci Adelaide SA Australia

The variable parameters (VP) X over bar control chart is more efficient than the fixed parameters X over bar control chart. However, an obvious shortcoming of the VP X over bar control chart is its excessive number of switches among different design parameters, which significantly increases the complexity of operations for administer and the costs of maintaining the control chart. Amin and Letsinger (1991) proposed a switching rule, denoted by A&L switching rule, to reduce the number of switches. In this paper, we investigated the economic design of the VP X over bar control chart by using the corrected A&L switching rule scheme, which makes some corrections to the existing study of the A&L switching rule scheme. A three-state Markov model is proposed to derive the performance measures of the suggested control chart. An expected cost model for the process is established with the cost function derived. The genetic algorithm is then employed to search for the solution for the economic design of the proposed control chart. The results obtained show that the developed model can significantly reduce the average number of the parameter's switches and save the expected cost in comparison with the conventional VP control scheme in detecting small and moderate mean shifts. A sensitivity analysis is also carried out to examine the effects of cost and model parameters on the solution of the economic design for the proposed control chart. The analysis demonstrates the expected cost per time unit is positively affected by the cost associated with a false signal, the average cost of repairs when a true signal is identified, the sampling cost and the cost associated with a switch, and is negatively affected by the cost associated with running the process in-control per hour. Copyright (c) 2013 John Wiley & Sons, Ltd.

关键词： economic design control chart a switching rule variable parameters genetic algorithm

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Existence of positive solution for a sixth-order differential system with variable parameters

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JOURNAL OF APPLIED MATHEMATICS AND COMPUTING 2014年第1-2期44卷 437-454页

作者： Agarwal, Ravi P. Kovacs, B. O'Regan, D. Texas A&M Univ Kingsville Dept Math 700 Univ Blvd Kingsville TX 78363 USA Univ Miskolc Dept Anal H-3515 Miskolc Hungary Natl Univ Ireland Sch Math Stat & Appl Math Galway Ireland

This paper investigates the existence of positive solutions for a sixth-order differential system with three variable parameters. Using a fixed point theorem and an operator spectral theorem we give some new existence... 详细信息

关键词： Positive solutions variable parameters Fixed point theorem Operator spectral theorem

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Integrated LCC-LCC Topology for WPT System With CC Output Regarding Air Gap and Load Variations

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IEEE TRANSACTIONS ON POWER ELECTRONICS 2024年第10期39卷 11904-11915页

作者： Jia, Yahui Zhao, Lei Wang, Zhihui Tang, Chunsen Chen, Fengwei Feng, Hui Chongqing Univ Sch Automat Chongqing 401331 Peoples R China

In magnetic coupling wireless power transfer systems, air gap and load changes are very common. Due to the presence of ferrite cores, changes in the air gap can lead to variations in coil parameters (mutual inductance and self-inductances), particularly in small air gap applications. This article proposes a constant current (CC) output method for LCC-LCC compensated WPT system with variable parameters. The proposed method utilizes an integrated magnetic coupler to provide a variable compensation inductance to offset output fluctuations caused by mutual inductance changes. In addition, compensation parameters for maintaining a CC output versus air gap and load changes are obtained through a particle swarm optimization (PSO) algorithm. An 800 W experimental setup is constructed to validate the effectiveness of the proposed method. The experimental results show that, when the output power varies from 400 to 800 W, within the air gap range of 15 to 50 mm, with a maximum self-inductance variation range of 23% and a maximum coupling coefficient variation range of 0.71 to 0.32, the system has a CC output characteristic with a maximum current fluctuation of only 4% and a maximum efficiency of 90.8%. A video demonstrating the variations in system key waveforms during air gap changes is attached to this article.

关键词： Coils Air gaps Inductance Couplings Couplers Topology Magnetic cores Constant current (CC) output integrated magnetic coupler magnetic coupling wireless power transfer (MC-WPT) particle swarm optimization (PSO) variable parameters

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