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Search Results: 1 - 10 of 78201 matches for " Jiaer Chen "
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Reduce proton energy spread by target ablation
Shuan Zhao,Chen Lin,Jiaer Chen,Xueqing Yan
Physics , 2015,
Abstract: It's shown that, with strong target ablation monoenergetic protons along the laser direction is available during the laser aluminum foil interaction, which is different from the classic TNSA theory. When the laser pre-pulse is too strong that the whole target is vaporized, the energetic electrons generated in the gas preplasma will play an important role for the ion acceleration because the sheath field will not be available. These electrons beam, which is highly directional, will setup triangle envelope acceleration field along the laser direction at the target rear, reducing the ion energy spread.
Drive laser system for the DC-SRF photoinjector at Peking University
Zhiwen Wang,Senlin Huang,Lin Lin,Gang Zhao,Shengwen Quan,Kexin Liu,Jiaer Chen
Physics , 2015,
Abstract: Photoinjectors are widely used for linear accelerators as electron sources to generate high-brightness electron beam. Drive laser, which determines the timing structure and quality of the electron beam, is a crucial device of photoinjector. A new drive laser system has been designed and constructed for the upgraded 3.5-cell DC-SRF photoinjector at Peking University. The drive laser system consists of a 1064 nm laser oscillator, a four- stage amplifier, the second and fourth harmonic generators, the optical system to transfer the UV pulses to the photocathode, and the synchronization system. The drive laser system has been successfully applied in the stable operation of DC-SRF photoinjector and its performance meets the requirements. 266 nm laser with an average power close to 1W can be delivered to illuminate the Cs2Te photocathode and the instability is less than 5% for long time operation. The design consideration for improving the UV laser quality, a detailed description of laser system, and its performance are presented in this paper.
Beam optimization of RFQ and SFRFQ combined accelerator at Peking University
Minglei Kang,Yuanrong Lu,Zhi Wang,Kun Zhu,Xueqing Yan,Shuli Gao,Shixiang Peng,Zhiyu Guo,Jiaxun Fang,Jiaer Chen
Physics , 2010,
Abstract: The Peking University Integral Split Ring Radio Frequency Quadrupole(ISR RFQ) accelerator was constructed in 1999 with a high duty factor 16.7% and repetition frequency 166Hz, and it was able to accelerate N+, O+,O-, C+ and He+ from 1.6kev/u to 65keV/u. It was later upgraded as an injector of the Separated Function RFQ (SFRFQ). The experiments indicated that the maximum accelerated O+ beam current could exceed 3.2mA with energy 1.03MeV and an energy spread (FWHM) 3.1%. Then the beam transports through a 1m-long magnetic triplet to the entrance of SFRFQ and is finally accelerated to 1.64MeV. The beam conditioning of RFQ were carefully optimized to satisfy the requirements of the SFRFQ. The combined accelerator eventually can deliver 0.53mA O+ beam with energy 1.65MeV, which has sufficiently demonstrated the feasibility of the SFRFQ structure.
Prospect of a very long baseline neutrino oscillation experiment: HIPA to Beijing
Hesheng Chen,Linkai Ding,Jingtang He,Haohuai Kuang,Yusheng Lu,Yuqian Ma,Lianyou Shan,Changquan Shen,Yifang Wang,Changgen Yang,Xinmin Zhang,Qingqi Zhu,Chengrui Qing,Zhaohua Xiong,Jin Min Yang,Zhaoxi Zhang,Jiaer Chen,Yanlin Ye,S. C. Lee,H. T. Wong,Kerry Whisnant,Bing-Lin Young
Physics , 2001,
Abstract: We discuss the prospects of a very long baseline neutrino oscillation experiment from HIPA to Beijing. The current understanding of neutrino oscillations, both theoretically and experimentally, are summarized. The figure of merits for interested physics measurements are defined and compared at different distances: 300 km, 700 km, 2100 km and 3000 km. We conclude that a baseline more than 2100 km is optimal. A large water cerenkov calorimeter was proposed and its performance is satisfactory from a Monte Carlo simulation study. Such a large detector can do many other measurements on cosmic-rays physics and astrophysics.
Research on the Incentive Mechanism of Hidilao Hotpot’s Employees Based on Grounded Theory  [PDF]
Chen Chen
Journal of Human Resource and Sustainability Studies (JHRSS) , 2018, DOI: 10.4236/jhrss.2018.61031
Abstract: The traditional classical incentive model only reveals the general rule of organizational incentive, and does not give specific operation rules. The matching between organizational incentives and employee needs is still black box, and it does not reveal its core operation mechanism from the perspective of mechanism. This paper took through the literature review, the Hidilao Hotpot company as a case study, through a variety of ways to collect data, the use of grounded theory to encode data analysis, and ultimately extracted 58 concepts, 26 sub-areas, 7 main areas, concluded that the Hidilao Hotpot Employee motivation formed the path, and ultimately extracted the micro-level employee motivation mechanism model. The research result of this article comes from the practice of the enterprise, which has enlightenment to the organizational incentive of the traditional catering industry and also provides a micro-research perspective and systematic mechanism research for the incentive field.
Digital Image Watermarking Based on Mixed Error Correcting Code  [PDF]
Yonghong Chen, Jiancong Chen
Journal of Information Security (JIS) , 2012, DOI: 10.4236/jis.2012.32018
Abstract: In this paper, we present a novel technique based on a mixed Error Correcting Code(ECC)-the convolutional code and the repetition code to enhance the robustness of the embedded watermark. Before embedding, the binary watermark is scanned to one-dimension sequence and later inputted into the (3, 1, 2) convolutional encoder and (3, 1) repetition encoder frame by frame, which will improve the error correcting capability of decoder. The output code sequence is scanned to some matrixes as the new watermark messages. The watermarking is selected in low frequency band of the Discrete Wavelet Transform (DWT) and therefore it can resist the destruction of image processing. Experimental results are presented to demonstrate that the robustness of a watermark with mixed ECC is much higher than the traditional one just with repetition coding while suffering JPEG lossy compression, salt and pepper noise and center cutting processing.
Operator Equation and Application of Variation Iterative Method  [PDF]
Ning Chen, Jiqian Chen
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.38127
Abstract: In this paper, we study some semi-closed 1-set-contractive operators A and investigate the boundary conditions under which the topological degrees of 1-set contractive fields, deg (I-A, Ω, p) are equal to 1. Correspondingly, we can obtain some new fixed point theorems for 1-set-contractive operators which extend and improve many famous theorems such as the Leray-Schauder theorem, and operator equation, etc. Lemma 2.1 generalizes the famous theorem. The calculation of topological degrees and index are important things, which combine the existence of solution of for integration and differential equation and or approximation by iteration technique. So, we apply the effective modification of He’s variation iteration method to solve some nonlinear and linear equations are proceed to examine some a class of integral-differential equations, to illustrate the effectiveness and convenience of this method.
Blow-Up and Attractor of Solution for Problems of Nonlinear Schrodinger Equations  [PDF]
Ning Chen, Jiqian Chen
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312263
Abstract: In this paper, the authors study the blow-up of solution for a class of nonlinear Schrodinger equation for some initial boundary problem. On the other hand, the authors give out some analyses and that new conclusion by Eigen-function method. In last section, the authors check the nonlinear parameter for light rule power by using of parameter method to get ground state and excite state correspond case, and discuss the global attractor of some fraction order case, and combine numerical test. To illustrate this physics meaning in dimension d = 1, 2 case. So, by numerable solution to give out these wave expression.
Some Approximation in Cone Metric Space and Variational Iterative Method  [PDF]
Ning Chen, Jiqian Chen
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312276
Abstract: In this paper, we give some new results of common fixed point theorems and coincidence point case for some iterative method. By using of variation iteration method and an effective modification of He’s variation iteration method discusses some integral and differential equations, we give out some new conclusion and more new examples.
Photoconductive Effect of Liquid and Utilization of Solar Energy  [PDF]
Ziwei Chen, Shihao Chen
Open Journal of Physical Chemistry (OJPC) , 2014, DOI: 10.4236/ojpc.2014.41003
Abstract:

Experiments described in this paper show that there is the photoconductive effect of liquid, i.e. when light shines into a sort of alkali, acid or salt solution, the conductivity of the solution will increase. The mechanism of the effect is explained as follows. When hydrated ions in the solution absorb photons with their high enough energies, they will decompose to naked ions and water-molecules. The naked ions can reach an anode or a cathode more easily and faster than the hydrated ions; It is possible that when a molecule in the solution absorbs a photon with its high enough energy, it will decompose to negative and positive ions. Based on the effect, a device producing hydrogen by the solar-energy had been devised.

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