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Polarization in Gamma-Ray Bursts Produced by Pinch Discharge

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Chinese Journal of Astronomy and Astrophysics 2005年第1期5卷 57-64页

作者： MeiWu lichen Ti-PeiLi KeyLab.ofParticleAstrophys. Inst.ofHighEnergyPhys.ChineseAcademyofSciencesBeijing100039 DepartmentofAstronomy BeijingNormalUniversityBeijing100875 KeyLab.ofParticleAstrophys. Inst.ofHighEnergyPhys.ChineseAcademyofSciencesBeijing100039／／CenterforAstrophysicsTsinghuaUniversityBeijing100084

Large-voltage, high-temperature plasma columns produced by pinch discharge can generate γ-ray flashes with energy spectra and spectral evolution consistent with what are observed in γ-ray bursts (GRBs), and the inverse Compton scattering (ICS) during the discharge process can produce high linear polarization. Our calculation indicates that the observed polarization depends on the angle between the line-of-sight to the GRB and the direction of the pinch discharge, but only weakly depends on observed γ-ray energy.

关键词： gamma-ray bursts radiation mechanism non-thermal polarization

Solid catalysts for the dehydrogenation of long-chain alkanes:lessons from the dehydrogenation of light alkanes and homogeneous molecular catalysis

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Science China Chemistry 2022年第11期65卷 2163-2176页

作者： Hongliu Wan Nengfeng Gong lichen Liu Department of Chemistry Tsinghua UniversityBeijing 100084China State Key Laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001China National Energy Center for Coal to Clean Fuels Synfuels China Co.Ltd.Beijing 101407China

Long-chain alkanes are abundant feedstocks supplied by natural resources and chemical industry. Specially, normal long-chain alkanes are primary products from Fischer-Tropsch synthesis(FTS) process, which is an important route for the utilization of coal in China. Facing a shift of energy nexus towards sustainable society, the conversion of long-chain alkanes derived from coal into value-added products(such as alkenes and oxygenates) is of great importance for securing China’s energy supply and the role transition of the commercial FTS plants from fuel makers to chemical suppliers. Among the potential transformation routes,the direct dehydrogenation of long-chain alkanes into alkenes is an attractive and practical route, due to the broad applications of long-chain alkenes(especially the linear α-olefins). In this review, we will summary the key insights obtained from the literature on the dehydrogenation of light alkanes based on supported metal catalysts and the dehydrogenation of alkanes with homogeneous molecular catalysts and then discuss how to translate these lessons into the development of efficient catalysts and processes for the dehydrogenation of long-chain alkanes into long-chain alkenes.

关键词： long-chain alkanes catalytic dehydrogenation α-olefins subnanometric cluster zeolite

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A Novel and Efficient Catalytic System for Aerobic Oxidative Coupling of 2-Naphthol Derivatives

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Chinese Chemical Letters 2004年第8期15卷 903-906页

作者： lichen JingBoLAN ZhiHuaMAO XiaoQiYU RuGangXIE DepartmentofChemistry SichuanUniversityChengdu610064

The paper reported a novel and efflcient aerobic oxidative coupling reaction of 2-naphthol derivatives catalyzed by CuCu (Ⅰ or Ⅱ)N-alkylimidazole complexes in excellent yields. The crystal structure of CuCu (Ⅱ)N-me... 详细信息

关键词： Binaphthol oxidative coupling Cu (Ⅰ or Ⅱ)-N-alkylimidazole complex.

A Pulse Immunization Model for Inhibiting Malware Propagation in Mobile Wireless Sensor Networks

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Chinese Journal of Electronics 2014年第4期23卷 810-815页

作者： WANG Xiaoming HE Zaobo ZHANG lichen School of Computer Science Shaanxi Normal University Department of Computer Science Georgia State University

Mobile wireless sensor networks(MWSNs)may be under attack due to their large-scale characteristics. One of the main threats is to inject malware into some nodes. To prevent malware from spreading in a largescale MWSN, an effective measure is to immunize susceptible nodes by disseminating and installing security patches. This work suggests a novel modeling framework and some mathematical models based on the pulse differential equation and the epidemic theory, in which the immunization operations are implemented on susceptible nodes in a pulse way. The maximum immunization period of time is derived to minimine the number of immunization operations while ensuring malware extinct over time in the MWSN. The theoretical results are confirmed by extensive simulations.

关键词： MWSN Malware propagation Susceptibleinfected-recovered(SIR) Pulse differential equation Maximum immunization period of time

Energy Efficient Forwarding Algorithm in Opportunistic Networks

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Chinese Journal of Electronics 2016年第5期25卷 957-964页

作者： ZHANG Feng WANG Xiaoming JIANG Liping ZHANG lichen Ministry of Education Key Laboratory for Modern Teaching Technology Shaanxi Normal University School of Computer Science Shaanxi Normal University

In opportunistic networks, a successful message transmission between node pairs depends on the message size, the transmission speed and the connection duration time. This paper proposes a new message forwarding algorithm to improve the message delivery ratio and reduce the energy consumption. Previous encounter characteristics between nodes are used to estimate future connection duration time using a three point estimation method. Furthermore, the buffer utilization of nodes is used as a weight for the likelihoods to meet destinations according to the hop count of messages stored in the *** simulation results show that the proposed forwarding algorithm achieves higher delivery ratio and less overhead ratio than the other four popular routing *** addition, the proposed algorithm gains a better average residual energy performance among all the compared protocols.

关键词： Opportunistic networks Forwarding algorithm Connection duration time Hop count Buffer management

Plasticity dependence on amorphous continuity in Fe-SiOC dual-phase nanocomposites

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Journal of Materials Science & Technology 2024年第6期173卷 80-85页

作者： Weiming Li lichen Bai Kaisheng Ming Shijian Zheng Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin 300130China

*** High strength and large deformability are greatly desirable for advanced structural metallic *** strengthening methods in crystalline materials rely on controlling the generation,propagation,and intersection of di... 详细信息

关键词： strengthening amorphous phase

Preparation and characterization of core-shell Al@PFHP with improving the combustion and ignition properties of aluminum powder

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Particuology 2023年第6期77卷 62-70页

作者： lichen Zhang Shuo Wang Xing Su Xiaodong Li Meishuai Zou School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China

The dense alumina shell on the surface of aluminum powder will hinder the combustion of aluminum powder and increase its ignition *** this study,the aluminum oxide shell layer on the surface of aluminum powder was removed with hydrofluoric acid by one-pot method,and 3-Perfluorohexyl-1,2-epoxypropane(PFHP)(F3C(CF2)5CH2C2H3O)was coated to form a uniform and controllable core-shell Al@*** core-shell AI@PFHP showed better thermal reaction and ignition *** exothermic enthalpy of Al@0.15 PFHP was increased by about 1.9 times,with lower ignition temperature(reduced by about 140℃)and longer burning duration(increased by about 1.5 times)after coating with PFHP,compared with raw aluminum *** addition,the formation of PFHP coating shell can effectively improve the hydrophobicity and corrosion resistance of aluminum powder.

关键词： Aluminumpowder Core-shell 3-Perfluorohexyl-1 2-Epoxypropane Combustion

Preparation of TiO2/MCM-41 by plasma enhanced chemical vapor deposition method and its photocatalytic activity

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Frontiers of Environmental Science & Engineering 2012年第3期6卷 304-312页

作者： Shenghung WANG Kuohua WANG Jihmirn JEHNG lichen LIU Department of Chemical Engineering Chung Hsing UniversityTaichung 402China Department of Labor Relations Chinese Culture UniversityTaipei 111China

Titanium dioxide is coated on the surface of MCM-41 wafer through the plasma enhanced chemical vapor deposition （PECVD） method using titanium isopropoxide （TTIP） as a precursor. Annealing temperature is a key factor affecting crystal phase of titanium dioxide. It will transform an amorphous structure to a polycrystalline structure by increasing temperature. The optimum anatase phase of TiO2 which can acquire the best methanol conversion under UV-light irradiation is obtained under an annealing temperature of 700℃ for 2 h, substrate tem- perature of 500~C, 70 mL. min1 of oxygen flow rate, and 100W of plasma power. In addition, the films are composed of an anatase-rutile mixed phase, and the ratio of anatase to rutile varies with substrate temperature and oxygen flow rate. The particle sizes of titanium dioxide are between 30.3 nm and 59.9nm by the calculation of Scherrer equation. Under the reaction conditions of ll6.8mg.L-1 methanol, 2.9mg.L-1 moisture, and 75~C of reaction temperature, the best conversion of methanol with UV-light is 48.2% by using the anatase-rutile （91.3/ 8.7） mixed phase TiO2 in a batch reactor for 60 min. While under fluorescent light irradiation, the best photoactivity appears by using the anatase-rutile （55.4/44.6） mixed phase TiO2 with a conversion of 40.0%.

关键词： photocatalyst titanium dioxide MCM-41 plasma enhanced chemical vapor deposition (PECVD)

Optimization-Based Fragmental Transmission Method for Video Data in Opportunistic Networks

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Tsinghua Science and Technology 2017年第4期22卷 389-399页

作者： Peng Li Xiaoming Wang Junling Lu lichen Zhang Zaobo He the Key Laboratory Modern Teaching Technology Ministry of Education School of Computer Science Shaanxi Normal University Department of Computer Science Georgia State University

Multimedia data have become popularly transmitted content in opportunistic networks. A large amount of video data easily leads to a low delivery ratio. Breaking up these big data into small pieces or fragments is a reasonable option. The size of the fragments is critical to transmission efficiency and should be adaptable to the communication capability of a network. We propose a novel communication capacity calculation model of opportunistic network based on the classical random direction mobile model, define the restrain facts model of overhead, and present an optimal fragment size algorithm. We also design and evaluate the methods and algorithms with video data fragments disseminated in a simulated environment. Experiment results verified the effectiveness of the network capability and the optimal fragment methods.

关键词： opportunistic network communication capabilities fragment video data