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Search Results: 1 - 10 of 127462 matches for " Zhang Xin-Ben "
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A New Ge/F Co-doped SMF with Enhanced SBS Threshold Fabricated by PCVD

LIU Tian,TONG Wei-Jun,ZHANG Fang-Hai,ZHANG Xin-Ben,DAI Neng-Li,LI Jin-Yan,

中国物理快报 , 2011,
Effects of structure parameters on the dispersion properties of dispersion compensation photonic crystal fiber

Chen Xiang,Zhang Xin-Ben,Zhu Xian,Cheng Lan,Peng Jing-Gang,Dai Neng-Li,Li Hai-Qing,Li Jin-Yan,

物理学报 , 2013,
Abstract: 光子晶体光纤由于其灵活可调的色散特性用作色散补偿具有极大的应用潜力. 设计了一种色散补偿光子晶体光纤, 并运用频域有限差分法模拟了其色散特性,从理论上分析了其结构参数孔间距Λ和空气占空比d/Λ对该光子晶体光纤的色散系数的影响, 并且实际制备出了3种不同结构参数的光子晶体光纤. 通过对其色散曲线对比分析表明: 当光子晶体光纤孔间距在1 μm附近时, 其色散系数随着孔间距Λ和占空比d/Λ的增大而增加, 但对于孔间距Λ的变化比占空比d/Λ更为敏感, 并且随着孔间距Λ的增加,其对色散系数的影响能力逐渐减小. 设计并制备的光子晶体光纤在1550 nm处的色散系数为-241.5 ps·nm-1·km-1, 相对色散斜率为0.0018, 具有较好的色散补偿能力.
Multiple Parton Scattering in Nuclei: Quark-quark Scattering
Schafer, Andreas;Wang, Xin-Nian;Zhang, Ben-Wei
High Energy Physics - Phenomenology , 2007, DOI: 10.1016/j.nuclphysa.2007.06.009
Abstract: Modifications to quark and antiquark fragmentation functions due to quark-quark (antiquark) double scattering in nuclear medium are studied systematically up to order \cal{O}(\alpha_{s}^2)$ in deeply inelastic scattering (DIS) off nuclear targets. At the order $\cal{O}(\alpha_s^2)$, twist-four contributions from quark-quark (antiquark) rescattering also exhibit the Landau-Pomeranchuck-Midgal (LPM) interference feature similar to gluon bremsstrahlung induced by multiple parton scattering. Compared to quark-gluon scattering, the modification, which is dominated by $t$-channel quark-quark (antiquark) scattering, is only smaller by a factor of $C_F/C_A=4/9$ times the ratio of quark and gluon distributions in the medium. Such a modification is not negligible for realistic kinematics and finite medium size. The modifications to quark (antiquark) fragmentation functions from quark-antiquark annihilation processes are shown to be determined by the antiquark (quark) distribution density in the medium. The asymmetry in quark and antiquark distributions in nuclei will lead to different modifications of quark and antiquark fragmentation functions inside a nucleus, which qualitatively explains the experimentally observed flavor dependence of the leading hadron suppression in semi-inclusive DIS off nuclear targets. The quark-antiquark annihilation processes also mix quark and gluon fragmentation functions in the large fractional momentum region, leading to a flavor dependence of jet quenching in heavy-ion collisions.
Multiple Parton Scattering in Nuclei: Beyond Helicity Amplitude Approximation
Ben-Wei Zhang,Xin-Nian Wang
Physics , 2003, DOI: 10.1016/S0375-9474(03)01003-0
Abstract: Multiple parton scattering and induced parton energy loss in deeply inelastic scattering (DIS) off heavy nuclei is studied within the framework of generalized factorization in perturbative QCD with a complete calculation beyond the helicity amplitude (or soft bremsstrahlung) approximation. Such a calculation gives rise to new corrections to the modified quark fragmentation functions. The effective parton energy loss is found to be reduced by a factor of 5/6 from the result of helicity amplitude approximation.
Heavy Quark Energy Loss in Nuclear Medium
Ben-Wei Zhang,Enke Wang,Xin-Nian Wang
Physics , 2003, DOI: 10.1103/PhysRevLett.93.072301
Abstract: Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark.
Quark-quark Double Scattering and Modified (Anti-)Quark Fragmentation Functions in Nuclei
Ben-Wei Zhang,Xin-Nian Wang,Andreas Schaefer
Physics , 2007, DOI: 10.1016/j.nuclphysa.2006.11.114
Abstract: Quark-quark double scattering in eA DIS and its contribution to quark and anti-quark fragmentation functions are investigated with the generalized factorization of the relevant twist-four processes in pQCD. It is shown that the resulting modifications to quark and anti-quark fragmentation functions are different. While the numerical size of these effects cannot be determined from pQCD, the structure of our result leads to a number of qualitative predictions for the relative size of the effect for different hadrons. These qualitative predictions agree with the multiplicity ratios for positive and negative hadrons as observed by HERMES.
Multiple Parton Scattering in Nuclei: Heavy Quark Energy Loss and Modified Fragmentation Functions
Ben-Wei Zhang,Enke Wang,Xin-Nian Wang
Physics , 2004, DOI: 10.1016/j.nuclphysa.2005.04.022
Abstract: Multiple scattering, induced radiative energy loss and modified fragmentation functions of a heavy quark in nuclear matter are studied within the framework of generalized factorization in perturbative QCD. Modified heavy quark fragmentation functions and energy loss are derived in detail with illustration of the mass dependencies of the Landau-Pomeranchuk-Migdal interference effects and heavy quark energy loss. Due to the quark mass dependence of the gluon formation time, the nuclear size dependencies of nuclear modification of the heavy quark fragmentation function and heavy quark energy loss are found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss of the heavy quark is also significantly suppressed due to limited cone of gluon radiation imposed by the mass. Medium modification of the heavy quark fragmentation functions is found to be limited to the large $z$ region due to the form of heavy quark fragmentation functions in vacuum.
Applying the mutation of Bacillus subtilis and the optimization of feather fermentation medium to improve Keratinase activity  [PDF]
Xin Zhang
Advances in Biological Chemistry (ABC) , 2012, DOI: 10.4236/abc.2012.21008
Abstract: Energetic Bacillus subtilis was preliminarily isolated from feather meal selection medium experiment, which could be used to produce Keratinase. Through using the ultraviolet ray produced by ultraviolet light and the compound mutation of sodium nitrite solution, a mutated strain was produced which can yield Kerati-nase with a high activity. The activity of Keratinase was 75.9% higher than that before the compound mutation. This was achieved by optimizing the fermentation medium of mutated strain. The optimum fermentation medium had the parameters as feather meal 5.5%, maize silage 0.8%, K+ 0.018 mol/L, Mg2+ 0.065 mol/L, Ca2+ 0.072 mol/L, Fe2+ 0.010 mol/L, and Na+ 0.088 mol/L. Based on the optimized fermentation medium, the highest yielding rate for producing enzyme was 1.117 U/mL, 25.22% higher than that before the optimization. The amino acid in the fermentation medium fluid reached 22.66 mg/mL. This paper presents a simple, and low cost way to produce high quality bio-fermentation feather meal.
Credit Constraints and Decisions in Exports: Theory under Asymmetric Information  [PDF]
Xin Zhang
Journal of Mathematical Finance (JMF) , 2012, DOI: 10.4236/jmf.2012.23026
Abstract: This paper examines why credit constraints for domestic and exporting firms arise in a setting where banks do not observe firms’ productivities. To maintain incentive-compatibility, banks lend below the amount needed for first-best production. The longer time needed for export shipments induces a tighter credit constraint on exporters than on purely domestic firms, even in the exporters’ home market. Greater risk faced by exporters also affects the credit extended by banks. Extra fixed costs reduce exports on the extensive margin, but can be offset by collateral held by exporting firms.
Air Marshal’s Investigation Power’s Research in Dealing with Hijacking Criminals  [PDF]
Xin Zhang
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.33026
Abstract: The power of investigation refers to the country’s investigation organ and investigators in order to achieve the purpose of the investigation: in accordance with legal procedures, using special investigative means to carry out the investigation activities of power. As the youngest police classification in China, Chinese air marshal is the important member that first faces the hijacking suspects, and the effective implementation of its investigation right is crucial on how to identify, investigate and prevent the hijacking behavior. This paper, using empirical analysis, comparative analysis and other research methods, aims to analyze and discuss how to overcome the defects of current Chinese air marshal’s investigation power existing in the hijacking in criminal cases, in order to obtain the earliest direct investigation clue, find the suspect, define the direction and determine the specific target of investigation, and then puts forward the conception and suggestion of some reform.
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