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|m| Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole

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Science china(physics,Mechanics & Astronomy) 2004年第6期47卷 676-684页

作者： WANG Jing & ZENG Jinyan Department of physics,Tsinghua university,beijing 100084,china school of physics,peking university,beijing 100871,china Department of physics Tsinghua University Beijing 100084 China school of physics Peking University Beijing 100871 China

The symmetry and |m| partial-wave analysis for two-dimensional (2D) Coulomb-scattering is investigated. As a function of energyE, the |m| partial-wave scattering amplitudef |m|(θ) is analytically continuated to the, negativeE (complexk) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles off |m|(θ) on the positive imaginaryk axis as is expected. In addition, as a function of |m|,f |m|(θ) is analytically continuated to the complex |m| plane, the bound state energy eigenvalues are just located at the poles off |m|(θ) on the positive real |m| axis.

关键词： two-dimensional Coulomb scattering, |m| partial-wave, Regge pole.

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Signal propagations and linkages of subsurface temperature anomalies in the tropical Pacific and Indian Ocean

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Progress in Natural Science:Materials International 2005年第9期15卷 804-809页

作者： QIAN Weihong** and HU Haoran(Monsoon & Environment Research Group, school of physics, peking university, beijing 100871, china) Monsoon and Environment Research Group School of Physics Peking University Beijing 100871 China

The propagation characteristics of signals along different zonal-time profiles are analyzed using surface and subsurface temperature anomalies over the tropical Pacific and Indian oceans. Analyses show that there are intrinsic relationships between El Nio events in the eastern equatorial Pacific and dipole events in the equatorial Indian Ocean. In the region of tropical North Pacific between the equator and 16°N, there is a circle of propagation of subsurface temperature anomalies. El Nio events only happen when the warm subsurface signals reach the eastern equatorial Pacific. Dipole events are characterized when a warm subsurface signal travels along off-equatorial Indian Ocean to the western boundary. From these analyses, we believe that subsurface temperature anomalies can be considered to be the oceanographic early signal to forecast El Nio events in Pacific Ocean and dipole events in Indian Ocean, respectively.

关键词： El Nio event dipole event subsurface sea temperature early signal.

Simulation of g factor for size optimization and coupling in phased array coil design

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Progress in Natural Science:Materials International 2006年第2期16卷 120-124页

作者： SONG Xiaoyu, ZHANG Hongjie, WANG Le, BAO Shanglian, SUN Yanrong and ZU Donglin (beijing Key Laboratory of Medical physics & Engineering, peking university, beijing 100871, china physics school, peking university, beijing 100871, china) beijing Key Laboratory of Medical physics and Engineering Peking University Beijing 100871 China physics school Peking University Beijing 100871 China

The effect of geometric parameters of the coil element in an array on signal-to-notse ratio (SNR) and g factor of parallel imaging are analyzed, and the optimal parameters for the maximal SNR and minimal g factor are also given in this paper. In addition, the effects of coupling on SNR and g factor have been analyzed. The test results indicate that g factor for parallel imaging is greatly increased and SNR is decreased for coupling. According to the optimization, a six-channel parallel coil has been designed for torso imaging.

关键词： MRI phased array coil SENSE parallel imaging.

Exact Periodic-Wave Solutions for(2+1)-Dimensional Boussinesq Equation and (3+1)-Dimensional KP Equation

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Communications in Theoretical physics 2004年第8期42卷 239-241页

作者： ZHAO Qiang LIU Shi-Kuo FU Zun-Tao school of physics, peking university, beijing 100871, china school of physics Peking University Beijing 100871 China

The(2+1)-dimensional Boussinesq equation and(3+1)-dimensional KP equation are studied by using theextended Jacobi elliptic-function *** exact periodic-wave solutions for the two equations are obtained.

关键词： Jacobi elliptic-function method (2+l)-dimensional Boussinesq equation (3+l)-dimensional KP equation periodic-wave solutions

Study of the structure of unstable nuclei through the reaction experiments

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 1-5页

作者： CAO ZhongXin & YE YanLin State Key Laboratory of Nuclear physics and Technology, school of physics, peking university, beijing 100871, china State Key Laboratory of Nuclear physics and Technology School of Physics Peking University Beijing China

Along with the development of the radioactive nuclear beam facility, the study of the structure of unstable nuclei has progressed rapidly over the last few decades. Due to the weakly binding property, the structure information of the unstable nuclei comes primarily from the scattering or reaction experiments. Therefore it would be very important to understand clearly the reaction mechanism involved in the experiment. We outlined here the major reaction mechanisms which are adequate to the study of unstable nuclei, with the focus on the new phenomena and methods in comparison with those with traditional stable nucleus beam. Especially emphasized are the breakup and knockout reactions, developed as accurate tools for spectroscopy investigation into the nuclear structure with low intensity secondary beam. Couplings of the breakup channel to the elastic scattering and the fusion and transfer reactions are also reviewed.

关键词： binaries: unstable nuclei nuclear structure breakup reaction knockout reaction fusion reaction transfer reaction

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Kinetic characteristics of continuous flow polymerase chain reaction chip: A numerical investigation

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Science china(Technological Sciences) 2010年第7期53卷 1967-1972页

作者： WANG ShiYing1 & WANG Wei2,3 1 school of physics, peking university, beijing 100871, china 2 Institute of Microelectronics, peking university, beijing 100871, china 3 National Key Laboratory of Science and Technology on Micro/Nano Fabrication, beijing 100871, china school of physics Peking University Beijing China Institute of Microelectronics Peking University Beijing China National Key Laboratory of Science and Technology on Micro/Nano Fabrication Beijing China

Continuous flow PCR (polymerase chain reaction) chip holds impressive advantages compared to micro chamber PCR chip. In order to have better understanding of kinetic characteristics of continuous flow PCR chip, a comprehensive mathematical model is presented in this paper, including melting, annealing and extension phases of a typical PCR process which has the essence of a convection-diffusion-reaction system. Using this model, we can simulate the PCR process in series of reaction cycles. Numerical results show that the average sample velocity plays a significant role in affecting the amplification efficiency. Also, appropriate combination of the PCR mixture is important for high-quality DNA amplification. Giving a large initial DNA concentration range, the continuous flow PCR scheme holds excellent real-time detection ability theoretically. The present numerical model bridges the temperature distribution to the real DNA amplification, and thereby is able to successfully predict continuous flow PCR properties which are important for the chip design.

关键词： continuous flow PCR chip numerical simulation convection-diffusion-reaction system

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Application of cathodoluminescence to zircon in FEG-ESEM

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Progress in Natural Science:Materials International 2006年第9期16卷 919-924页

作者： CHEN Li , XU Jun and SU Li (Electron Microscopy Laboratory, school of physics, peking university, beijing 100871, china Geology Experimental Center, china university of Geoscience, beijing 100083, china) Electron Microscopy Laboratory School of Physics Peking University Beijing 100871 China Geology Experimental Center China University of Geoscience Beijing 100083 China

Cathodoluminescence (CL) image analysis of zircon is a key step of mineral micro-area compositional investigation and U-(Th)-Pb dating. We introduce a system consisting of field emission ESEM and high performance cathodoluminescence. This system has obvious advantages in imaging resolution and CL spectrum. We acquired some zircon CL images and spectra to demonstrate the ability of this system. Our results show that this system has a great potential application to characterize and identify the genesis of zircon.

关键词： zircon cathodoluminescence ESEM.

Relationship between the tropical cyclone genesis over the Northwest Pacific and the sea surface temperature anomalies

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Progress in Natural Science:Materials International 2007年第10期17卷 1208-1212页

作者： Wang Jinbo, Qian Weihong and Zhang Xin(Monsoon and Environment Research Group, school of physics, peking university, beijing 100871, china) Monsoon and Environment Research Group School of Physics Peking University Beijing 100871 China

Using the tropical cyclone (TC) data derived from the Joint Typhoon Warning Center (JTWC) and the sea surface temperature data derived from the Joint Environmental Data Analysis Center (JEDAC) at the Scripps Institute of Oceanography from January 1955 to December 2000, we analyzed the relationship between the TC genesis over the Northwest Pacific (NWP) and the sea surface temperature anomalies (SSTA) over the Pacific basin. A long-term trend indicated that the highest frequency of monthly TC genesis appeared earlier and the annual genesis sum increased gradually during the last half century with some oscillations. No significant synchronous correlation was found between the NWP TC events and the SSTA over the Pacific basin, while the annual sum of TC genesis was closely related with the SSTA averaged from the first three months (January, February and March) of the year in the equatorial western and eastern Pacific and over mid-high latitudes of the North Pacific. The results implied that there are an interannual El Nio SSTA mode in the equatorial western and eastern Pacific and an interdecadal SSTA mode in the northern Pacific, which affected the TC genesis. A regression analysis between the first three-month SSTA and the annual TC sum based on two time scales was conducted. The correlation coefficient between simulated and observed TC sums reached a high value of 0.77.

关键词： tropical cyclone long-term trend sea surface temperature Pacific.

Design of an MRI quadrature-data acquisition card

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Progress in Natural Science:Materials International 2006年第3期16卷 255-259页

作者： JIANG Zhongde, ZU Donglin and GU Xiaofang (Institute of Heavy Ion physics, beijing Key Laboratory of Medical physics & Engineering, school of physics, peking university,beijing 100871, china) Institute of Heavy Ion physics Beijing Key Laboratory of Medical Physics and Engineering School of Physics Peking University Beijing 100871 China

A design of a quadrature-data acquisition card based on peripheral component interconnect (PCI) bus for mini-type magnetic resonance imaging (MRI) system is reported. It uses two high speed analog-to-digital converters (ADCs) to sample the MRI signals and two static random access memories (SRAMs) to store the data which will be read to the computer by PCI bus after sampling. All the logic control signals on the card are generated by the field programmable gate array (FPGA). The software Foundation3.1 is used to design the FPGA and achieve useful result after simulating and implementing. The card has some merits that normal commercial cards do not have. For example, the sampling parameters can be varied according to different pulse sequences.

关键词： MRI data acquisition FPGA PCI bus.