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Electromagnetic interference modeling and suppression techniques in variable-frequency drive systems

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Frontiers of Mechanical Engineering 2018年第3期13卷 329-353页

作者： Le YANG Shuo WANG jianghua FENG Electrical and Computer Engineering Department University of Florida Gainesville FL 32611 USA CRRC Zhuzhou Institute Co. Ltd. Zhuzhou 412001 China

Electromagnetic interference （EMI） causes electromechanical damage to the motors and degrades the reliability of variable-frequency drive （VFD） systems. Unlike fundamental frequency components in motor drive systems, high-frequency EMI noise, coupled with the parasitic parameters of the trough system, are difficult to analyze and reduce. In this article, EMI modeling techniques for different function units in a VFD system, including induction motors, motor bearings, and rectifierinverters, are reviewed and evaluated in terms of applied frequency range, model parameterization, and model accuracy. The EMI models for the motors are categorized based on modeling techniques and model topologies. Motor bearing and shaft models are also reviewed, and techniques that are used to eliminate bearing current are evaluated. Modeling techniques for conventional rectifierinverter systems are also summarized. EMI noise suppres- sion techniques, including passive filter, Wheatstone bridge balance, active filter, and optimized modulation, are reviewed and compared based on the VFD system models.

关键词： variable-frequency drive (VFD) electromagnetic interference (EMI) motor drive modeling EMI noise suppression

Relations of Microstructural Attributes and Strength-Ductility of Zirconium Alloys with Hydrides

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Chinese Journal of Mechanical Engineering 2023年第4期36卷 407-419页

作者： Chao Fang Xiang Guo jianghua Li Gang Chen School of Mechanical Engineering Tianjin UniversityTianjin 300354China Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin 300072China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China

As the first safety barrier of nuclear reactors,zirconium alloy cladding tubes have attracted extensive attention because of its good mechanical *** strength and ductility of zirconium alloy are of great significance to the service process of cladding tubes,while brittle hydrides precipitate and thus deteriorate the overall *** on the cohesive finite element method,the effects of cohesive strength,interfacial characteristics,and hydrides geometric characteristics on the strength and ductility of two-phase material(zirconium alloy with hydrides)are numerically *** results show that the fracture behavior is significantly affected by the cohesive strength and that the overall strength and ductility are sensitive to the cohesive strength of the zirconium ***,the interface is revealed to have prominent effects on the overall fracture *** the cohesive strength and fracture energy of the interface are higher than those of the hydride phase,fracture initiates in the hydrides,which is consistent with the experimental *** addition,it is found that the number density and arrangement of hydrides play important roles in the overall strength and *** simulation provides theoretical support for the performance analysis of hydrogenated zirconium alloys during nuclear reactor operation.

关键词： Zirconium alloy Hydride Strength and ductility Cohesive finite element method Microcrack initiation and propagation

Characteristics of pollutants behavior in a stormwater constructed wetland during dry days

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Frontiers of Environmental Science & Engineering 2012年第5期6卷 649-657页

作者： jianghua YU Kisoo PARK Youngchul KIM College of Environmental Science and Engineering Nanjing University of Information Science and Technology Nanjing 210044 China Department of Environment Engineering Hanseo University Seosan 356706 R. O. Korea

A stormwater wetland treating non-point source pollution （NPS） from a 64 ha agricultural watershed was monitored over a period of five months. The results indicated that pH and dissolved oxygen （DO） were increased in the wetland due highest total suspended solids to the algal growth. The （TSS） concentration was observed in the aeration pond due to the resuspension of solids, decreased in the wetland. The respective decreases in total nitrogen （TN） and total kjeldahl nitrogen （TKN） were 15.9% and 28.7% on passing through the wetland. The nitrate and ammonia were increased by 45.4% and decreased by 79.9%, respectively. These variations provided strong evidence for the existence of nitrification. The total phosphorus （TP） and phosphate had respective reductions of 52.3% and 58.2% over the wetland. The total chemical oxygen demand （TCOD） and soluble chemical oxygen demand （SCOD） were also decreased. generally, the TN, TP and phosphate removal etticiencies were positive. These positive removal efficiencies were mainly due to microbial activities, uptake by plants, and chemical precipitation at high pH. Negative removal efficiencies can be caused by continuous rainfall activities, with short antecedent dry days （ADDs） and unstable hydraulic conditions, some other biogeochemical transformations and algal growth also being important parameters.

关键词： constructed stormwater wetland dry days,nitrification and denitrification pollutants characteristic

Redox-neutral photocatalytic strategy for selective C–C bond cleavage of lignin and lignin models via PCET process

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Science Bulletin 2019年第22期64卷 1658-1666页

作者： Yinling Wang Yue Liu jianghua He Yuetao Zhang State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University

It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and *** have developed a redox-neutral photocatalytic strategy to accomplish this goal in both b-O-4 and b-1 lignin models at room temperature(RT)via proton-coupled electron transfer(PCET)process without any pretreatments of substrate,by adjusting the alkalinity of base to obtain a lignin models/base PCET pair with a bond dissociation free energy close to 102 kcal/*** breaking down C_b–Ccbond and any C–O bonds,this PCET method is 100%atom economy and produces exclusive Ca–C_bbond cleavage products,such as benzaldehydes(up to 97%)and phenyl ethers(up to 96%),in high to excellent yields and *** studies indicated that the PCET strategy is also effective for the depolymerization of native lignin at RT,thus providing significantly important foundation to the depolymerization of lignin.

关键词： C–C bond cleavage Lignin depolymerization Photocatalysis Proton-coupled electron transfer Redox-neutral

Divergent Branch Threads Compaction for Efficient SIMD Control Flow

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Chinese Journal of Electronics 2015年第2期24卷 288-294页

作者： YANG Hui CHEN Shuming WAN jianghua XU Xiaolu School of Computer National University of Defense Technology Institute of Aeronautical Meteorology Equipment Academy of Air Force

Wide Single instruction multiple data(SIMD) architectures are very important in the computeintensive applications. The SIMD execution model is inefficient when it suffers from the divergent control *** divergent execution paths across loop iterations take place sequentially on SIMD, which defeats part of the efficiency advantage of SIMD execution. This paper proposes a mechanism to compact the divergent branch threads to mitigate the impact of branch thread divergence on SIMD architectures. It relaxes the SIMD execution model by allowing the distinct instruction flows to be scheduled independently, instead of one single instruction flow. It increases flexibility and mitigates the synchronization cost of co-issuing instructions from different divergent branch threads by giving the Vector processing elements(VPEs)the ability to direct their own control flow. The proposed divergent branch threads compaction mechanism improves performance by 2.56 x over traditional SIMD architecture for a wide variety of general purpose parallel applications while the area overhead only increases 6.48%.

关键词： SIMD Multiple instruction multiple data(MIMD) Vector branch thread Conditional operations Control flow

Existence of rainbow matchings in properly edge-colored graphs

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Frontiers of Mathematics in China 2012年第3期7卷 543-550页

作者： Guanghui WANG jianghua ZHANG Guizhen LIU School of Mathematics Shandong UniversityJinan 250100China School of Management Shandong UniversityJinan 250100China

Let G be a properly edge-colored graph. A rainbow matching of G is a matching in which no two edges have the same color. Let 5 denote the minimum degree of G. We show that if Iv（G）I 〉（σ2 ＋ 14σ ＋ 1）/4, then G has a rainbow matching of size 6, which answers a question asked by G. Wang [Electron. J. Combin., 2011, 18： #N162] affirmatively. In addition, we prove that if G is a properly colored bipartite graph with bipartition （X, Y） and max{lXl, IYI} 〉（σ2 ＋ 4σ - 4）/4, then G has a rainbow matching of size σ.

关键词： Rainbow matching properly edge-colored graph

Representation of the ENSO Combination Mode and its Asymmetric SST Response in Different Resolutions of HadgeM3

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Advances in Atmospheric Sciences 2018年第8期35卷 167-180页

作者： jianghua WAN Hongli REN Peili WU Laboratory for Climate Studies and CMA-NJU Joint Laboratory for Climate Prediction Studies National Climate Center China Meteorological Administration Beijing 100081 China Department of Atmospheric Sciences School of Environment Studies University of Geoscience Wuhan 430074 China Met Office Hadley Center Exeter EX1 3PB UK

Previous studies have revealed a combination mode （C-mode） occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates the simulation of this C-mode and its asymmetric SST response in HadgeM3 and its resolution sensitivity using three sets of simulations at horizontal resolutions of N96, N216 and N512. The results show that HadgeM3 can capture well the spatial pattern of the C-mode associated surface wind anomalies, as well as the asymmetric response of SST in the tropical Pacific, but it strongly overestimates the explained variability of the C-mode compared to the ENSO mode. The model with the three resolutions is able to reproduce the distinct spectral peaks of the C-mode at the near annual combination frequencies, but the performance in simulating the longer periods is not satisfactory, presumably due to the unrealistic simulation of the ENSO mode. Increasing the horizontal resolution can improve the consistency between atmospheric and oceanic representations of the C-mode, but not necessarily enhance the accuracy of C-mode simulation compared with observation.

关键词： ENSO combination mode asymmetric response Nifio-A index HadgeM3 horizontal resolution

Yaw controller design of stratospheric airship based on phase plane method

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Chinese Journal of Aeronautics 2016年第3期29卷 738-745页

作者： Miao Jinggang Zhou jianghua Nie Ying Yang Xin Academy of Opto-Electronics Chinese Academy of ScienceBeijin 100094China University of Chinese Academy of Science Beijing 100049China

Recently, stratospheric airships prefer to employ a vectored tail rotor or differential main propellers for the yaw control, rather than the control surfaces like common low-altitude airship. The load capacity of vectored mechanism and propellers are always limited by the weight and strength, which bring challenges for the attitude controller. In this paper, the yaw channel of airship dynamics is firstly rewritten as a simplified two-order dynamics equation and the dynamic charac- teristics is analyzed with a phase plane method. Analysis shows that when ignoring damping, the yaw control channel is available to the minimum principle of Pontryagin for optimal control, which can obtain a Bang-Bang controller. But under this controller, the control output could he bouncing around the theoretical switch curve due to the presence of disturbance and damping, which makes adverse effects for the servo structure. Considering the structure requirements of actuators, a phase plane method controller is employed, with a dead zone surrounded by several phase switch curve. Thus, the controller outputs are limited to finite values. Finally, through the numerical simulation and actual flight experiment, the method is proved to be effective.

关键词： Attitude control Dynamics modeling Optimal control Phase plane method Stratospheric airship

A high order collaboration and real time formal model for automatic testing of safety critical systems

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Frontiers of Computer Science 2015年第4期9卷 495-510页

作者： jianghua LV ShUong MA Xianjun LI Jiangong SONG State Key Lab of Software Development Environment School of Computer Science Beihang University Beijing 100191 China

The need for safety critical systems （SCS） is both important and urgent, and their evaluation and verification are test-dependent. SCS are usually complex and very large, so manual testing of SCS are infeasible in practice, and develop- ing automatic test approaches for SCS has become an impor- tant trend. This paper defines a formal semantics model for automatic test of SCS, called AutTMSCS, which describes behaviors in SCS testing. The model accommodates the high order collaboration in real time and temporariness of SCS testing. Testing tasks, test equipment and products under test are abstracted and architected in three layers, and a method for automatic testing is given. Based on extended label tran- sition system （LTS）, the convergency and correctness of the model are proved to demonstrate the computability of the model, indicating that the testing process of SCS can be au- tomatic.

关键词： safety critical systems (SCS) test automatictest equipment collaboration high order calculus LTS realtime