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The iteration method of solving a type of three-point boundary Value Problem
Xiping Liu,Mei Jia 한국전산응용수학회 2009 Journal of applied mathematics & informatics Vol.27 No.3
This paper studies the iteration method of solving a type of second-order three-point boundary value problem with non-linear term f, which depends on the first order derivative. By using the upper and lower method, we obtain the sufficient conditions of the existence and uniqueness of solutions. Furthermore, the monotone iterative sequences generated by the method contribute to the minimum solution and the maximum solu- tion. And the error estimate formula is also given under the condition of unique solution. We apply the solving process to a special boundary value problem, and the result is interesting. This paper studies the iteration method of solving a type of second-order three-point boundary value problem with non-linear term f, which depends on the first order derivative. By using the upper and lower method, we obtain the sufficient conditions of the existence and uniqueness of solutions. Furthermore, the monotone iterative sequences generated by the method contribute to the minimum solution and the maximum solu- tion. And the error estimate formula is also given under the condition of unique solution. We apply the solving process to a special boundary value problem, and the result is interesting.
THE ITERATION METHOD OF SOLVING A TYPE OF THREE-POINT BOUNDARY VALUE PROBLEM
Liu, Xiping,Jia, Mei The Korean Society for Computational and Applied M 2009 Journal of applied mathematics & informatics Vol.27 No.3
This paper studies the iteration method of solving a type of second-order three-point boundary value problem with non-linear term f, which depends on the first order derivative. By using the upper and lower method, we obtain the sufficient conditions of the existence and uniqueness of solutions. Furthermore, the monotone iterative sequences generated by the method contribute to the minimum solution and the maximum solution. And the error estimate formula is also given under the condition of unique solution. We apply the solving process to a special boundary value problem, and the result is interesting.
Liu, Xiping,Jin, Jingfu,Jia, Mei The Korean Society for Computational and Applied M 2012 Journal of applied mathematics & informatics Vol.30 No.1
In this paper, we study a class of integral boundary value problems for fractional differential equations. By using some fixed point theorems, the results of existence of at least three positive solutions for the boundary value problems are obtained.
Xiping Liu,Jingfu Jin,Mei Jia 한국전산응용수학회 2012 Journal of applied mathematics & informatics Vol.30 No.1
In this paper, we study a class of integral boundary value problems for fractional differential equations. By using some fixed point theorems, the results of existence of at least three positive solutions for the boundary value problems are obtained.
Liu, Xiping,Wang, Chen,Zheng, Aihua Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.3
The operation principle of an axial flux-switching hybrid excitation synchronous machine (AFHESM) is analyzed and its topology structures are proposed in this paper. After some comprehensive analysis of the operation principle to axial flux electrical machine, flux-switching electrical machine and hybrid excitation electrical machine, the operation principle of AFHESM is given. Combined with some typical topological structures of hybrid excitation electrical machine, some possible topological structures are proposed and some comprehensive comparisons are carried out. The analysis results show that the stator-separated AFHESM has some advantages such as less AM turns, less impact on the demagnetization of PM, less magnetic flux-leakage and higher efficiency compared to other topologies.
A Stator-Separated Axial Flux-Switching Hybrid Excitation Synchronous Machine
Liu, Xiping,Zheng, Aihua,Wang, Chen Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.4
In this paper, a stator-separated axial flux-switching hybrid excitation synchronous machine (SSAFHESM) is presented, of which the structure and operational principle are introduced. The magnetic field distribution under different excited currents is analyzed, and some characteristics including flux-linkage, EMF and field control ability are studied by finite element analysis (FEA). Tests are carried out on a 12/10-pole prototype machine to validate the analysis results, and an excellent agreement is obtained.
Weiliang Wu,Xiping Liu,Jianwei Liang,Zhangqi Liu,Chaozhi Huang 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.3
Medium- and high-voltage motors are characterized by high power and large inertia, and are widely used in industrial frequency conversion. The cascaded H-bridge multilevel (CHB-ML) inverter adopts a modular design concept to realize high-voltage and high-power functions by cascading multiple identical low-voltage conversion units. Moreover, the harmonic content of the output current of the inverter is small. For this purpose, a multilevel inverter consisting of eight H-bridge inverter units cascaded in each phase is introduced to drive medium- and high-voltage asynchronous motors for starting and frequency regulation. The carrier phase-shifted sinusoidal pulse-width modulation technique, DC voltage equalization control of power unit, and speed sensorless vector control strategy based on a voltage–current hybrid chain observer are mainly introduced. The simulation and experimental results of the real-time digital simulation system (RTDS) of the asynchronous motor dragged by the inverter verify that the CHB-ML inverter with the proposed control strategy has good starting and frequency regulation performance. These findings provide a technical guarantee for the field of medium- and high-voltage high-power drives.
A DC Charging Pile for New Energy Electric Vehicles
Wu Weiliang,Liu Xiping,Huang Chaozhi 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6
New energy electric vehicles will become a rational choice to achieve clean energy alternatives in the transportation field, and the advantages of new energy electric vehicles rely on high energy storage density batteries and efficient and fast charging technology. This paper introduces a DC charging pile for new energy electric vehicles. The DC charging pile can expand the charging power through multiple modular charging units in parallel to improve the charging speed. Each charging unit includes Vienna rectifier, DC transformer, and DC converter. The feasibility of the DC charging pile and the effectiveness of the control strategies of each component of the charging unit are verified by simulation and experimental results. This DC charging pile and its control technology provide some technical guarantee for the application of new energy electric vehicles.
LICONG WANG,YUAN LIU,YUSHAN ZHANG,DAN CHEN,YUQI WANG,ZELIANG DONG,YONGCHAO LU,XIPING HUANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.7
Magnesium borate (Mg 2 B 2 O 5 Þ nanorods were synthesized by a two-step process, includingsolution-chemical technology and a ternary-°ux method, using concentrated seawater and H 3 BO 3as raw materials. X-ray di®raction (XRD) showed that the sample had triclinic structure. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM) indicated that it consisted of rod-like particles with an average diameter of 100 – 150 nmand length over 5 ? m. Di®erential thermal analysis (DTA) con¯rmed that the melting point ofthe ternary-°ux and the formation temperature of Mg 2 B 2 O 5 were lower than single-°ux process. The formation of Mg 2 B 2 O 5 nanorods was more e±cient by ternary-°ux than single-°ux. Me-chanical property of Mg 2 B 2 O 5 nanorods reinforced Nylon-6 composites showed that KH550 wasthe optimal coupling agent and made the strength of the composites to be improved to differentdegrees.