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A new compensation current real-time computing method for power active filter based on double linear construction algorithm

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Science China(Technological Sciences) 2006年第4期49卷 485-512页

作者： LI Zicheng SUN Yukun College of Electrical and Information Engineering of Jiangsu University Zhenjiang 212013 China College of Electrical and Information Engineering of Jiangsu University Zhenjiang 212013 China

Considering the detection principle that “when load current is periodic current, the integral in a cycle for absolute value of load current subtracting fundamental active current is the least”, harmonic current real-time detection methods for power active filter are proposed based on direct computation, simple iterative algorithm and optimal iterative algorithm. According to the direct computation method, the amplitude of the fundamental active current can be accurately calculated when load current is placed in stable state. The simple iterative algorithm and the optimal iterative algorithm provide an idea about judging the state of load current. On the basis of the direct computation method, the simple itera- tive algorithm, the optimal iterative algorithm and precise definition of the basic concepts such as the true amplitude of the fundamental active current when load current is placed in varying state, etc., the double linear construction idea is proposed in which the amplitude of the fundamental active current at the moment of the sample is accurately calculated by using the first linear construction and the condition which disposes the next sample is created by using the second linear construction. On the basis of the double linear con- struction idea, a harmonic current real-time detection method for power active filter is proposed based on the double linear construction algorithm. This method has the char- acteristics of small computing quantity, fine real-time performance, being capable of ac- curately calculating the amplitude of the fundamental active current and so on.

关键词： power active filter, harmonic current, active current, reactive current.

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Turbulent lock release gravity current

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Science China(Technological Sciences) 2001年第5期44卷 449-462页

作者：陈国谦 Joseph H.w.Lee National Laboratory for Turbulence Research Department of Mechanics Peking University Beijing 100871China

The time evolution of a turbulent lock release gravity current, formed by a finite volume ofhomogeneous fluid released instantaneously into another fluid of slightly lower density, was studied byexperimental measurements of the density structure via elaborate digital image processing and by a nu-merical simulation of the flow and mixing using a two-equation turbulence model. The essential fact thatthe gravity current passes through an initial slumping phase in which the current head advances steadilyand a second self-similar phase in which the front velocity decreases like the negative third power of thetime after release is satisfactorily presented by the laboratory observation. An overall entrainment ratioproportional to the distance from the release point is found by the numerical simulation. The renormal-ization group (RNG) k- ε model for Reynolds-stress closure is validated to characterize the gravitycurrent with transitional and localized turbulence.

关键词： turbulence modeling, gravity current, environmental hydraulics.

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The density matrix picture of laser coherent control current

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Science China(Physics,Mechanics & Astronomy) 2004年第2期47卷 231-243页

作者： SHOU Qian ZHANG Haichao LIU Luning LIN Weizhu State Key Laboratory of Optoelectronic Materials and Technologies Zhongshan (Sun Yat-Sen) UniversityGuangzhou 510275 China State Key Laboratory of Optoelectronic Materials and Technologies Zhongshan (Sun Yat-Sen) UniversityGuangzhou 510275 China State Key Laboratory of Optoelectronic Materials and Technologies Zhongshan (Sun Yat-Sen) UniversityGuangzhou 510275 China State Key Laboratory of Optoelectronic Materials and Technologies Zhongshan (Sun Yat-Sen) UniversityGuangzhou 510275 China

The physical substance of the coherent control current and the optical rectification have been analyzed based on density matrix perturbation theory. The analytical results demonstrate that they arise from the real and virtual manifestations of the same nonlinear process associated with diagonal and non-diagonal density matrix. And in terms of polarization, they respectively arise from the intraband and interband polarizations. Both the evolution of the coherent control current exited by ultrafast laser pulse and its dependence on frequency have been studied in time and frequency domains. In order to get an explicit knowledge of intraband polarization and the origination of the coherent control current, we have investigated the initial photo-carriers momentum distribution. The ultrafast decay of the polar momentum population in order of tens of femtosends is given to illustrate its instantaneous optical response.

关键词： density matrix, Feynman diagrams, coherent control current, intraband polarization.

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The characteristics of action potential and nonselec-tive cation current of cardiomyocytes in rabbit superior vena cava

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Science China(Life Sciences) 2008年第4期51卷 326-335页

作者： WANG Pan, YANG XinChun, LIU XiuLan, BAO RongFeng & LIU TaiFeng Beijing ChaoYang Hospital, Capital Medical University, Beijing 100020, China 1. Beijing ChaoYang Hospital Capital Medical University Beijing 100020 China

As a special focus in initiating and maintaining atrial fibrillation (AF), cardiomyocytes in superior vena cava (SVC) have distinctive electrophysiological characters. In this study, we found that comparing with the right atrial (RA) cardiomyoctyes, the SVC cardiomyoctyes had longer APD90 at the different basic cycle lengths; the conduction block could be observed on both RA and SVC cardiomyoctyes. A few of SVC cardiomyoctyes showed slow response action potentials with automatic activity and some others showed early afterdepolarization (EAD) spontaneously. Further more, we found that there are nonselective cation current (INs) in both SVC and RA cardiomyocytes. The peak density of INs in SVC cardiomyocytes was smaller than that in RA cardiomyocytes. Removal of extracellular divalent cation and glucose could increase INs in SVC cardiomyocytes. The agonist or the antagonist of INs may in-crease or decrease APD. To sum up, some SVC cardiomyocytes possess the ability of spontaneous activity; the difference of transmembrane action potentials between SVC and RA cardiomyocytes is partly because of the different density of INs between them; the agonist or the antagonist of INs can in-crease or decrease APD leading to the enhancement or reduction of EAD genesis in SVC cardiomyo-cytes. INs in rabbit myocytes is fairly similar to TRPC3 current in electrophysiological property, which might play an important role in the mechanisms of AF.

关键词： superior vena cava cardiomyocytes, right atrial cardiomyocytes, nonselective cation current, action potential atrial fibrillation, rabbit heart

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The Contribution of the Nearest-Neighborhood Interaction to the Persistent current in a Mesoscopic Ring Studied by a New Model

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Communications in Theoretical Physics 2001年第12期36卷 715-722页

作者： HE Guang-Ping LI Hua-Zhong MA Zhong-Shui Advanced Research Center Zhongshan University Guangzhou 510275 China Advanced Research Center Zhongshan University Guangzhou 510275 China Advanced Research Center Zhongshan University Guangzhou 510275 China

We propose an effective description of the interaction between the nearest-neighboring particles in a continuum theory. The contributions of the electron-electron interaction to the persistent current in 1D strongly correlating mesoscopic rings with or without impurities are analyzed. It is shown that the nearest-neighborhood int eraction gives significant contributions to the current and correlation functions. The enhance of the theoretical value of current magnitude is observed at finite temperature in the presence of the impurity scattering. The statistical property of the persistent current over random impurity distribution is also discussed. It is found that the exponential law of the persistent current for a non-interacting system will remain in an interacting one, as long as the interactions between nonnearest-neighborhoods are excluded.

关键词： strongly correlated electron systems, persistent current, mesoscopic systems

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Experimental Study of Hydrodynamic Loading on Submarine Composite Pipelines under the Action of Waves and current

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China Ocean Engineering 1994年第2期9卷 159-170页

作者： Ma Liang , Wang Jinying Xing Zhizhuang Sun Shaoshu Professor, Dalian University, Dalian 116024 Senior Engineer, China Offshore Oil Engineering Co.(TG), Tangu, Tainjin Professor, Dalian University of Science and Technology, Dalian 116024 Associate Professor, Dalian University of Science and Technology, Dalian 116024

This article is aimed at the experimental study of the hydrodynamic loading induced by waves and current acting on the JZ 20-2 submarine composite pipelines. The corresponding hydrodynamic coefficients obtained in thi... 详细信息

关键词： submarine pipeline hydrodydnamic coefficient regular waves irregular waves current,

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Effects of water wave motion on pollutant transport in shallow coastal water

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Science China(Technological Sciences) 2002年第6期45卷 593-605页

作者：陶建华韩光 1. Department of Mechanics Tianjin University 300072 Tianjin China

Based on the study of the wave propagation, breaking, longshore current and the effect of wave on current structure in the near shore area with a mild bottom slope, the wave is considered to be an important dynamic factor for pollutant transportation in the coastal water. Numerical simulation shows that the pollutant will transfer along shore when the incident wave is at an angle to the shoreline. This phenomenon is very significant if the outfall is located in the surfzone. Therefore, in the design of sea outfall, to improve near shore environment, the water wave should be considered as an important hydrodynamic factor.

关键词： pollutant transport, water wave, tide current, longshore current, sea outfall.

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Geomagnetic responses in high latitudes during the storm of July 15—16, 2000

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Science China Mathematics 2002年第z1期45卷 132-141页

作者：陈耿雄杜爱民徐文耀陈鸿飞洪明华彭丰林师恩齐 Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100101 China

The ionospheric equivalent currents in the high latitudes and the auroral electrojet sys- tem during the geomagnetic storm on July 15-16, 2000 are analyzed by using geomagnetic data from IMAGE chain. The large-scale vortices of equivalent currents are observed in the storm. The vortices on the dusk side of ionosphere correspond to four-celled pattern of plasma convection associated with NBZ, region I and region II field-aligned currents. Only one vortex can be found on the dawn side of ionosphere after interplanetary magnetic field (IMF) turns southward. In the initial phase of the storm, the center of eastward electrojets tends to shift equatorward. It arrives at 58.62 latitude of corrected geomagnetic coordinates (CGM). The westward electrojets are strong in the main phase. The center of westward electrojets in this period moves equatorward and may be beyond the southernmost station (56.45°) of the chain.

关键词： magnetic storm, field-aligned current, equivalent current, auroral electrojet.

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Vertical Structure of Baroclinic currents over Northern South China Sea Continental Slope

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Marine Science Bulletin 2001年第1期3卷 1-8页

作者： Qiu Zhang(邱章) South China Sea Institute of Oceanology the Chinese Academy of Sciences Guangzhou 510301

The 28.6 d time series of ADCP currents at 27 depth levels, (11,15,…,115m) which are obtained from a mooring station at the northern South China Sea continental slope, have been decomposed into barotropic and baroclinic components. The emphasis in this paper is on the analysis of the time series of baroclinic currents by means of several methods,such as the tidal harmonic analysis, the power spectra and the kinetic energy *** major results are as follows: (1) In respect of the baroclinic currents, the values of several parameters first decrease and then increase with depth. These parameters include the temporal mean value of the cross-shelf component, the standard deviations, the amplitudes of K1 constituents, the mean eddy kinetic energy, as well as the significant peaks of the power spectra of the cross-shelf components. (2) The diurnal period of the baroclinic currents is dominant. The diumal tidal current rotates clockwise and the major axis of current ellipse is located along the directions of NW-SE. The vertical distribution of the phases of the diurnal constituent varies with the different water layers. Around the 67m depth level, the phase changes very *** those layers far away from the 67m depth level, the vertical distribution of the phase is relatively stable, but with opposite phases in the upper and lower water layers. For the upper layers between the surface and 67m,the phases are around 300°; for the lower layers between 67m and 115m, the phases are around 120° .(3) The mean eddy kinetic energy of the baroclinic current is quite large, accounting for 41% of the mean kinetic energy of the measured currents. The cross-shelf component is larger than the along-shelf one. The two baroclinic current components correspond to the major and minor axes of the current ellipse of the diurnal constituent respectively. (4) The power spectra of the baroclinic currents show a singnificant period of about 24h, with 23.6h at both 19m and 99m and 24.4h at

关键词： Northern South China Sea, barotropic current, baroclinic current

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