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Design and simulation of electrical dynamometer using improved DTC induction motor driver

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Journal of Central South University 2017年第6期24卷 1360-1368页

作者： ZHU Cheng-li wang yan-zhong HOU Liang-wei School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China

AC motors, especially the squirrel cage induction motors have the advantages of simple structure, good reliability and low cost. They are more suitable to be used as electrical dynamometers to provide dynamic load for bench test systems. But, the speed and torque of induction motors are not easy to be controlled accurately. In this work, an electrical dynamometer based on the induction motor is proposed. In order to get better control performance of torque and speed of induction motor, an improved direct torque control method(DTC) is also developed based on the space vector modulation(SVM) technique. The performance of the proposed dynamometer system is validated in the Matlab/Simulink platform. The simulation results show that the new dynamometer has good torque and stator flux response. And the torque and stator current ripples of it are reduced significantly compared with using the conventional DTC method.

关键词： dynamometer induction motor direct torque control (DTC) direct torque control method-space vector modulation DTC-SVM PI controller

Adsorption Site and State of Nitrogen Atom on Ru(0001),(1010) Low-index and (1120),(1121) Stepped Surfaces

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Chemical Research in Chinese Universities 2009年第5期25卷 705-710页

作者： DIAO Zhao-yu YU Hai-yan wang zhong-ni ZHANG Xue-na wang Ze-xin Department of Chemistry Shandong Normal University Jinan 250014 P. R. China

The adsorptions of nitrogen atoms on Ru（0001）, （1010） low index surfaces and （1120）, （1121） stepped surfaces were investigated by the five-parameter Morse potential（5-MP） method in details, Calculated results demonstrate that N atoms show a tendency to be adsorbed at threefold sites. No subsurface state was found for N atoms on Ru（1010） surface. There exist 6 stable adsorption sites for N atoms on Ru（1121） stepped surface which can be classified into 3 types： the on-surface adsorption state, the facet adsorption state and the subsurface state. Moreover, two new perpendicular vibrations at 97 and 98 meV are predicted. All calculated results are in good accord with HR-EELS experiments.

关键词： N-Ru system 5-MP Surface adsorption

THREE-DIMENSIONAL SIMULATION FOR EFFECTS OF BED DISCORDANCE ON FLOW DYNAMICS AT Y-SHAPED OPEN CHANNEL CONFLUENCES

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Journal of Hydrodynamics 2007年第5期19卷 587-593页

作者： wang Xiao-gang yan zhong-min GUO Wei-dong College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China College of Water Conservancy Shenyang Agricultural University Shenyang 110161 China

Channel confluences are universally present in nature. They can be divided into two types： asymmetrical river confluences and symmetric river confluences. The latter is also called as the Y-shaped confluences. Most of previous work has paid more attention to the asymmetrical river confluences, but few studies have been conducted on the Y-shaped confluences. In this article, the effects of bed discordance on the flow patterns at ＂Y＂ shaped open-channel confluences were studied by using a 3-D numerical simulation. It is proved that the model can undertake quantitative assessment of the flow at confluences. The results indicate that there are a lot of differences between the Y-shaped confluence and asymmetrical confluence. The discordant bed height plays an important role at the Y-shaped junction.

关键词： Y-shaped junction discordant bed height,separation zone numerical simulation turbulent intensity,secondary flow lateral mixing

Synthesis and Characterization of Layered Co_2(OH)_3(CH_3COO)·H_2O

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Chemical Research in Chinese Universities 2011年第6期27卷 910-914页

作者： ZHENG De-shan wang yan-zhong SHI Li-min SUN Si-xiu School of Materials and Chemical Engineering Xi＇an Technological University Xi＇an 710032 P. R. China School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China

Layered hydroxide metal acetate Co2（OH）3（CH3COO）·H2O with an interlayer spacing of 1.282 nm has been synthesized by a novel method which is employed in ethanol-aqueous mixed solvents media. Experiment results show that the purity of the product by the modified method is higher compared with that by the previous methods. A complete characterization of the as-prepared samples was performed by means of X-ray powder diffraction, IR spectroscopy, scanning electron microscope, as well as magnetic measurement. The facile and effective approach for the preparation of this compound in this study is very interesting and important because it has wide application in the field of anionic exchange reaction for the synthesis of hybrid organic-inorganic compounds.

关键词： Anionic exchange reaction Hybrid organic-inorganic compound Layered hydroxide cobalt acetate Magnetic property

Changes in the Vision-related Resting-state Network in Pituitary Adenoma Patients After Vision Improvement

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Chinese Medical Journal 2015年第9期128卷 1171-1176页

作者： Hai-yan Qian Xing-Chao wang zhong-yan wang Zhen-Min wang Pi-Nan Liu zhong-Cheng wang Department of Neurosurgery Beijing Tiantan Hospital Affiliated to Capital Medical University Beijing 100050 China Beijing Neurosurgery Institute Capital Medical University Beijing 100050 China Department of Radiology Beijing Tiantan Hospital Affiliated to Capital Medical University Beijing 100050 China

Background：The aim of this research was to investigate the changes in the vision-related resting-state network （V-RSN） in pituitary adenoma （PA） patients after vision improvement,which was induced by operative ***：Ten PA patients with an improved visual acuity or/and visual field after transsphenoidal pituitary tumor resection were recruited and underwent a complete neuro-ophthalmologic evaluation,as well as an magnetic resonance imaging （MRI） protocol,including structural and resting-state functional MRI sequences before and after the *** regional homogeneity （ReHo） of the V-RSN was *** sample t-test was performed to identify the significant differences in the V-RSN in the PA patients before and after transsphenoidal pituitary tumor ***：Compared with the preoperation counterparts,the PA patients with improved vision after the operation exhibited reduced ReHo in the bilateral thalamus,globus pallidus,caudate nucleus,putamen nucleus,supplementary motor area,and left hippocampal formation,and increased ReHo in the bilateral cuneus gyrus,calcarine gyrus,right lingual gyrus,and fusiform ***：PA patients with improved vision exhibit increased neural activity within the visual cortex,but decreased neural activity in subareas of the multisensory and multimodal systems beyond the vision cortex.

关键词： Multisensory and Multimodal System Pituitary Adenoma Resting-state Functional Magnetic Resonance Imaging Visual Improvement

Design and implementation of a position sensorless control method for brushless DC motors

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Journal of Chongqing University 2016年第2期15卷 43-51页

作者：朱成礼 wang yan-zhong School of Mechanical Engineering and Automation Beihang University Beijing 100191 P. R. China

Because brushless direct current(BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric traction systems. It is known that the BLDC motors have no brushes for commutation. They are commutated with electronically commutation. So, the rotor position information of the BLDC motors must be known to understand which winding will be energized according to the energizing sequence. In most of the existing BLDC motor drivers, rotor position information is detected by Hall effect sensors. This kind of mechanical position sensors will bring additional connections and costs, reliability decrease and noise increase. In order to improve the control performance and extend the range of speed regulation for BLDC motors, a position sensorless control method is proposed in this paper. In the proposed control method, rotor position information of the BLDC motors is detected from the back electromagnetic forces(back-EMFs) which are estimated by an unknown-input observer with line to line currents and line to line voltages. For the purpose of verifying the effectiveness of the proposed control method, a model is built and simulated on the Matlab/Simulink platform. The simulation results show that the speed regulation performance of BLDC motors is improved compared with using Hall effect sensors. At the same time, the reliability of the BLDC motors is improved and the costs of them are reduced because the position sensor is eliminated.

关键词： brushless DC motor brushless direct current(BLDC) speed control position sensorless inverter

Formation mechanisms and distribution of high quality reservoirs in deep strata in Palaeogene in northern steep slope zone of Bonan sag, Jiyang depression, China

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Journal of Central South University 2015年第7期22卷 2665-2680页

作者：马奔奔操应长贾艳聪王艳忠 School of Geosciences China University of Petroleum

Petrographic analysis combined with various techniques, such as thin section identification, petro-physical property testing, mercury penetration, oil testing results, was used to assess basic reservoir characteristics of deep strata in Palaeogene in the northern steep slope zone of the Bonan sag, China. The formation mechanisms of high quality reservoirs in deep strata were discussed according to evolution characteristics of paleopressures and paleofluids in geological period. The deep reservoirs have poor physical properties and mainly develop extra-low porosity, extra-low and ultra-low permeability reservoirs. Reservoir spaces mainly consist of secondary pores and overpressure fractures. Early overpressure, early hydrocarbon filling and dissolution by early organic acids are the major formation mechanisms of high quality reservoirs. The conglomerate in inner fan which had a poor primary physical property mainly experienced strong compaction and calcareous matrix recrystallization. The physical properties of the inner fan were poor with weak dissolution because of poor mobility of fluid. The reservoirs mainly are type IV reservoirs and the distribution extends with the burial depth. The braided channel reservoirs in the middle fan had relative good primary physical properties and strong ability to resist compaction which favored the preservation of primary pores. Large amounts of the secondary porosities were created due to dissolution by early organic acids. A series of micro-fractures generated by early overpressures would be important migration pathways for hydrocarbon and organic acids. Furthermore, early overpressures had retarded maturation of organic matters and organic acids which had flowed into reservoirs already and could keep in acid environment for a long time. This process would contribute significantly to reinforcing the dissolution and enhancing the reservoir quality. The braided channel reservoirs were charged with high oil saturation preferential

关键词： deep strata high quality reservoirs formation mechanism Palaeogene Bonan sag

Diagenetic evolution and its effect on reservoir-quality of fan delta sandstones during progressive burial: Evidence from the upper part of the fourth member of Shahejie formation, Bonan sag, Jiyang depression

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Journal of Central South University 2015年第8期22卷 3042-3058页

作者：马奔奔操应长王艳忠张少敏贾艳聪 School of Geosciences China University of Petroleum

Petrographic analysis combined with various techniques, such as thin section identification, fluid inclusions, isotopic data, petro-physical property testing and oil testing results, was used to study diagenetic evolution and its effect on reservoir-quality of fan delta reservoirs of Es4s in the Bonan sag. The diagenesis is principally characterized by strong compaction, undercompaction, multi-phase of dissolution and cementation. Compaction played a more important role than cementation in destroying the primary porosity of the sandstones. The reservoirs have experienced complicated diagenetic environment evolution of "weak alkalineacid-alkalinity-acid-weak alkalinity" and two-stage of hydrocarbon filling. The diagenetic sequences are summarized as "early compaction/early pyrite/gypsum/calcite/dolomite cementation→feldspar dissolution/the first stage of quartz overgrowth → early hydrocarbon filling→quartz dissolution/anhydrite/Fe-carbonate cementation→Fe-carbonate dissolution/feldspar dissolution/ the second stage of quartz overgrowth→later hydrocarbon filling→later pyrite cementation. In the same diagenetic context, the diagenetic evolution processes that occurred in different sub/micro-facies during progressive burial have resulted in heterogeneous reservoir properties and oiliness. The braided channel reservoirs in fan delta plain are poorly sorted with high matrix contents. The physical properties decrease continually due to the principally strong compaction and weak dissolution. The present properties of braided channel reservoirs are extremely poor, which is evidenced by few oil layers developed in relatively shallow strata while dry layers entirely in deep. The reservoirs both in the underwater distributary channels and mouth bars are well sorted and have a strong ability to resist compaction. Abundant pores are developed in medium-deep strata because of modifications by two-stage of acidic dissolution and hydrocarbon filling. The present properties are relat

关键词： diagenetic evolution deep strata fan delta Es4s Bonan sag

Detection of BCR ABL Gene Rearrangement by RT/PCR Technology and Its Mechanism in the Generation and Development of Chronic Myeloid Leukemia

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Chemical Research in Chinese Universities 1999年第4期15卷 378-380页

作者： CHEN Huai-yong wang yan-zhong GOU Xiao-jun LI Xiang-hui wang Yong-ting DING Tian-bing LI Qing-shan ZENG Ling-fang ZHAO Lu-lu College of Life Science Jilin UniversityChangchun 130023P.R.China Department of Biochemistry Beijing Norma l Univer sityBeijing 100875P.R.China Cha ngchun Higher College of Medical Sciences Changchun 130031P.R.China