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Analysis of the stress ratio of anisotropic rocks in uniaxial tests

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International Journal of Mining Science and Technology 2017年第3期27卷 531-535页

作者： Wang Miaomiao Li pei wu Xiaowa Xu Dan Key Laboratory of Shale Gas and Geoengineering Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China

The effect of structural discontinuities on the progressive failure process of anisotropic rocks should be paid particular *** crack damage stress σ_(cd),also considered as the yield strength,and the relationship between σ_(cd) and the uniaxial peak strength σ_(ucs) of anisotropic rocks for different orientations 8 of the isotropy planes with respect to the loading directions were investigated theoretically and experimentally.A theoretical relation of σ_(cd)/σ_(ucs) with the function of the shape parameter m was ***,uniaxial compression tests of shale samples were conducted for several inclinations θ.The test result of σ_(cd)/σ_(ucs) was close to the theoretical value for a given ***,both experimental results and theoretical solutions of σ_(cd)/σ_(ucs) were independent of the inclination θ while σ_(cd) andσ_(ucs) were strongly affected by θ.The strength ratio σ_(cd)/σ_(ucs) may therefore be an intrinsic property of anisotropic rocks and could be used to predict the failure of rock samples.

关键词： Anisotropic rocks Uniaxial compression test Brittle failure Crack damage stress Stress ratio

Virtual three dimensions reconstruction and isoline analysis of human marks on the surface of animal fossils

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Chinese Science Bulletin 2009年第9期54卷 1564-1569页

作者： wu XianZhu WANG YunFu pei ShuWen wu XiuJie Laboratory of Scientific Archaeology Chongqing Normal University Chongqing 400047 China Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044 China

Animal fossils in archaeological sites are closely related to human activities. The environment and human activities, such as hunting-selection, cook process, traditional culture and habits can be partly inferred from the variety of fauna, fragmentation of the bones, and the human marks on bones' sur-faces. So far, researches about marks on fossils are few in China, and are mainly observed directly by eyes. Light Microscopes and Scanning Electron Microscopes are also applied to the observation abroad. These methods could provide us a lot of information, but are mainly confined to 2 dimensions. In this paper, we analyze human marks on the surface of animal fossils through three dimensions re-construction and isoline analysis, which enable us observe and measure in 3 dimensions. This method gives us a lot of information as follows: the formation of the marks, the tools that produced the marks, the cutting edge, movement and micro-abrasion of the tools. Through study of human marks on the surface of animal fossils unearthed from Bailongdong Cave in Yunxi, Hubei Province, we have got the characteristics of the marks, and further deepen cognition of the cutting edge, cutting orientation, cut-ting sequence, as well as micro-abrasion of tools during the formation of these marks. This is the first to use virtual three dimensions reconstruction in studying the human marks on the surface of animal fossils in China.

关键词：人类活动动物化石等值线分析三维重建表面虚拟扫描电子显微镜工具磨损

Iron-Catalyzed Reductive C(aryl)—Si Cross-Coupling of Diaryl Ethers with Chlorosilanes

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Chinese Journal of Chemistry 2024年第6期42卷 578-584页

作者： pei Liu Baowei wu Xuefeng Cong Jie Kong School of Chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi'anShaanxi710072 China Institute of Molecular Plus Department of Chemistry and Haihe Laboratory of Sustainable Chemical TransformationsTianjin University92 Weijin RoadTianjin300072 China

The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great ***,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized *** combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive *** low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.

关键词： Cross-coupling Diaryl ethers Chlorosilanes C—O bond cleavage Iron catalyst 3d transition metals Selectivity Regioselectivity

Privacy Preserving Algorithm for Spectrum Sensing in Cognitive Vehicle Networks

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Chinese Journal of Electronics 2024年第1期33卷 30-42页

作者： Hongning LI Tonghui HU Jiexiong CHEN Xiuqiang wu Qingqi pei Guangzhou Institute of Technology Xidian University Guangzhou CEPREI Shaanxi Key Laboratory of Blockchain and Secure Computing

The scarcity of spectrum resources fails to meet the increasing throughput demands of vehicular networks. There is an urgent need to maximize the utilization of spectrum bands in mobile networks. To ascertain the availability of spectrum bands, users should engage in wireless channel sensing and collaboration. However, spectrum sensing data always involves users’ privacy, such as their location. This paper first introduces sensing trajectory inference attack in cognitive vehicular networks and then proposes a data confusion-based privacy-preserving algorithm and a cryptonym array-based privacy-preserving aggregation scheme for spectrum sensing in cognitive vehicular networks. Unlike existing methods, the proposed schemes transmit confused data during the aggregation process. This deliberate obfuscation makes it almost impossible to infer users’ location from the transmitted data. The analysis demonstrates the resilience of the proposed schemes against sensing trajectory inference attack.

关键词： Privacy Data privacy Wireless sensor networks Authentication Data aggregation Throughput Inference algorithms

Quasi-concave optimization of secrecy redundancy rate in HARQ-CC system

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Science China(Information Sciences) 2020年第2期63卷 160-173页

作者： Yue wu Shishu YIN Jian ZHOU pei YANG Hongwen YANG School of Management Science and Engineering Anhui University of Finance and Economics School of Information and Communication Engineering Beijing University of Posts and Telecommunications

In a hybrid automatic repeat request with chase combining(HARQ-CC) system, we analyze physical layer secure performance and determine the secrecy redundancy rate by proposed quasi-concave optimization methods with effective secrecy throughput(EST) criteria. First, key performance metrics,including connection outage probability(COP), secrecy outage probability(SOP), EST, and delay, are discussed. Then, under the constraint of COP, we optimize the secrecy redundancy rate to maximize the EST,which is a quasi-concave function, by both the bisection and fixed-point methods. Furthermore, under the simultaneous constraints of COP and SOP, the bisection and Lagrangian multiplier methods are applied to optimize the secrecy redundancy rate. From the comparison of the numerical and simulated results, it is concluded that EST demonstrates practical secure performance of HARQ-CC, and the proposed optimization methods adjust the secrecy redundancy rate for improved security.

关键词： physical layer security(PLS) hybrid automatic repeat request(HARQ) chase combining(CC) effective secrecy throughput(EST) quasi-concave optimization

Evolution of dark energy–dark matter-coupled expanding universe

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Chinese Science Bulletin 2014年第33期59卷 4473-4477页

作者： Ti-pei Li Mei wu department of Physics Center for Astrophysics Tsinghua University Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences

The present universe is dominated by repulsive dark energy. It is natural that the coupling between the dark energy and the attractive gravity has to be taken into account in studying the evolution of our universe. Here, we induce an evolution equation for dark energy–dark mattercoupled universe. The solutions of the dynamic equation provide a specific picture of cosmic evolution, which is well compatible with current observed evolution histories of both Hubble parameter and equation of state parameter of dark energy. In this picture, the already observed universe has undergone through three epochs—the epoch of equilibrium between gravity and dark energy at cosmological redshifts z [ 1, the phase transition epoch at z between about 0.5 and 1, and the present acceleration epoch starting from z ' 0:5. The expected matter-dominated deceleration epoch has not been seen yet, which requires future deep observations to look back upon more early universe.

关键词：膨胀宇宙暗能量耦合暗物质演变演化方程动力学方程吸引力

A Possible Glitch of Gamma-Ray Pulsar Geminga?

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Chinese Physics Letters 1998年第1期15卷 74-75页

作者： ZHANG Shu LI Ti-pei wu Mei Laboratory of Cosmic Ray and High Energy Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100039

Timing analyses of gamma-ray pulsar Geminga were made to check its rotating stability using released energetic gamma-ray experiment(EGRET)*** motions of Geminga were found from EGRET data in *** analysis of parameters searching and bootstrap testing showed that the parameters are getting worse when including EGRET data in *** of these results may indicate that a small glitch of Geminga occurred in 1995.

关键词： Geminga pulsar rotating

Choice for graphene as conductive additive for cathode of lithium-ion batteries

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Journal of Energy Chemistry 2019年第3期28卷 19-26页

作者： Ying Shi Lei Wen Songfeng pei Minjie wu Feng Li Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Graphene is a promising conductive additive for the lithium-ion batteries(LIBs) and shows great potential especially with its fast development of the large scale fabrication technology. This work has explored the influence of the incorporation of graphenes prepared by three typical methods on the electrochemical performance of the LiCoO_2-based cathode focusing on the choice for the effective graphene as conductive additive for the cathode of LIBs. Through the comparison of the intrinsic characteristics of graphenes and the electrochemical performance of electrodes with graphene, it is found that graphene with low disorder degree and large size is not suitable for LiCoO_2 cathodes as conductive additive. Conversely, the graphene with oxygen functional groups, relatively low surface area and proper size displays much better electrochemical performance when it is used as conductive additive. This work also demonstrates the transmission mechanism for different graphenes as conductive additives in the LiCoO_2 materials, and further reveals that the conductivity of graphene is not the only factor as conductive additives, surface chemistry and sheet size of the graphene are also essential factors which greatly influence the electrochemical performance of electrode. In addition, when combined with Super P, only 1% graphene is enough to construct an efficient conductive network in the electrode. This study also gives a new sight on the practical application of graphene as conductive additive for high performance LIBs.

关键词： Graphene Conductive additive Lithium-ion batteries LiCoO2 cathode

Compton Telescope Observation of Gamma-Ray Flare from Quasar PKS0528+134

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Chinese Physics Letters 1997年第5期14卷 395-398页

作者： ZHANG Shu LI Ti-pei wu Mei Institute of High Energy Physics Chinese Academy of SciencesBeijing 100039

The quasar PKSO528+134 was observed to flare by the energetic gamma-ray experiment(EGR-ET)γ-ray telescope on the Compton gamma-ray observatory during the viewing period 213(VP213).The Compton telescope data from VP213 have been reanalyzed by using the direct demodulation *** of the source are obtained at energies above 3 MeV and the time variability in the energy range 10-30 MeV is consistent with the result of *** is no spectral break at energies above 3 MeV during the flare.

关键词： method. spectral Observation