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Simulation study of phase retrieval for hard X-ray in-line phase contrast imaging

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 450-458页

作者： YU Bin1,2, PENG Xiang1,2, TIAN Jindong1, NIU Hanben1, DIAO Luhong3.& LI Hua3.1. key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, Institute of Optoelec- tronics, Shenzhen University, Shenzhen 518060, china 2. state key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 3.0072,china 3. key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, beijing 100080,china 1. key Laboratory of Optoelectronic Devices and Systems of Ministry of Education Institute of Optoelectronics Shenzhen University 518060 Shenzhen China 2. state key Laboratory of Precision Measuring Technology and Instruments Tianjin University 300072 Tianjin China 3. key Laboratory of Intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences 100080 Beijing China

Two algorithms for the phase retrieval of hard X-ray in-line phase contrast imaging are presented. One is referred to as Iterative Angular Spectrum Algorithm (IASA) and the other is a hybrid algorithm that combines IASA with TIE (transport of intensity equation). The calculations of the algorithms are based on free space propagation of the angular spectrum. The new approaches are demonstrated with numerical simulations. Comparisons with other phase retrieval algorithms are also performed. It is shown that the phase retrieval method combining the IASA and TIE is a promising technique for the application of hard X-ray phase contrast imaging.

关键词： X-ray optics, phase contrast imaging, phase retrieval, angular spectrum, hard X-ray.

Characterization of plastic flow in two Zr-based bulk metallic glasses

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Science china(Technological Sciences) 2006年第4期49卷 414-424页

作者： XING Dongmei1,2, ZHANG Taihua1, LI Weihuo3.& WEI Bingchen3.1. state key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sci- ences, beijing 100080,{3. 2. College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 3.0074,{3. 3. National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, beijing 100080,{3. 1. state key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China 2. College of Physics and Electronic Information Science Tianjin Normal University Tianjin 300074 China 3. National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Plastic deformation behaviors of Zr65Al10Ni10Cu15 and Zr52.5Al10Ni10Cu15Be12.5 bulk metallic glasses (BMGs) are studied by using the depth-sensing nanoindentation, microindentation and uniaxial compression. The Be-containing BMG exhibits a signifi- cantly improved overall plastic strain compared with the Be-free alloy during compressive tests. Both BMGs show a loading-rate-dependent serrated flow during nanoindentation measurements, but the Be-containing alloy exhibits a much lower critical loading rate for the disappearance of the serration than the Be-free BMG. The shear band patterns de- veloped during plastic deformation are investigated by microindentation technique, wherein much higher shear band density is found in the Be-containing alloy than in the Be-free alloy, indicating an easier nucleation of shear bands in the former BMG. The dif- ference in the plastic deformation behavior of the two BMGs can be explained by a free volume model.

关键词： Bulk metallic glass, plastic deformation, shear band, nanoindentation.

Study on NDVI-T_s space by combining LAI and evapotranspiration

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Science china Earth Sciences 2006年第7期49卷 747-754页

作者： HAN Lijuan1,2,3. WANG Pengxin4, YANG Hua1,2,3. LIU Shaomin1,2,3.& WANG Jindi1,2,3.1. Research Center for Remote Sensing and GIS, School of Geography, beijing Normal University, beijing 100875, china 2. {3. key Laboratory of Remote Sensing Science, beijing 100875, china 3. beijing key Laboratory for Remote Sensing of Environment and Digital Cities, beijing 100875, china 4. Department of Information Management, College of Information and Electronic Engineering, china Agricultural University, beijing 100083. china 1. Research Center for Remote Sensing and GIS School of Geography Beijing Normal University Beijing 100875 China 2. state key Laboratory of Remote Sensing Science Beijing 100875 China 3. beijing key Laboratory for Remote Sensing of Environment and Digital Cities Beijing 100875 China 4. Department of Information Management College of Information and Electronic Engineering China Agricultural University Beijing 100083 China

This paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and on analyzing transformation conditions, the physical and ecological meanings of the vegetation index-surface temperature space as well. Further, we use the Tempera-ture-Vegetation Dryness Index (TVDI) to explain the existent meaning of a triangular space after NDVI reaches its saturated state by employing the relationships between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts are useful for describing, validating and updating land surface models.

关键词： NDVI, land surface temperature, evapotranspiration, leave area index.

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central china: Constraints from geochemistry and melt inclusions

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Science china Earth Sciences 2005年第8期48卷 1146-1157页

作者： SU Li1,2, SONG Shuguang3.& ZHOU Dingwu1 1. key Laboratory of Continental Dynamics of the Ministry of Education, Department of Geology, Northwestern University, Xi’an 710069, china 2. The Geological Lab Center, china University of Geosciences ({3.), {3. 100083. china 3. key Laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, Peking University, {3. 100871, china 1. key Laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University 710069 Xi’an China 2. The Geological Lab Center China University of Geosciences 100083 (Beijing)Beijing China 3. key Laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University 100871 Beijing China

The Songshugou dunite body, which occupies an area of about 20 km2, is the largest ultramafic massif in the eastern Qinling orogenic belt, Central china. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2O3. CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

Quantum threshold group signature

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Science china(Physics,Mechanics & Astronomy) 2008年第10期51卷 1505-1514页

作者： YANG YuGuang1,2,3.& WEN QiaoYan4 1 College of Computer Science and Technology, beijing University of Technology, beijing 100124, china 2 {3. key Laboratory of Integrated Services Network, Xidian University, Xi’an 710071, china 3.{3. key Laboratory of Information security (Graduate University of Chinese Academy of Sciences), beijing 100049, china 4 {3. key Laboratory of Networking and Switching Technology, beijing University of Posts and Tele-communications, beijing 100876, china College of Computer Science and Technology Beijing University of Technology Beijing 100124 China state key Laboratory of Integrated Services Network Xidian University Xi’an 710071 China state key Laboratory of Information security Graduate University of Chinese Academy of Sciences Beijing 100049 China state key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization, a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem. Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t-1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t-1 or fewer receivers cannot verify the validity of the signature.

关键词： threshold quantum signature trusted party quantum cryptography

Another ID-Based Proxy Signature Scheme and Its Extension

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Wuhan University Journal of Natural Sciences 2007年第1期12卷 33-36页

作者： ZHANG Jianhong1,2 , ZOU Wei3.1. College of Science, North china University of Technology, beijing 100041,china 2. Institute of Software of Chinese Academy of Sciences /{3. key Laboratory of Information security, beijing 100080, china 3. Institute of Computer Science and Technology, Peking University, beijing 100871, china College of Science North China University of Technology Beijing China state key Laboratory of Information security Institute of Software of Chinese Academy of Sciences Beijing China Institute of Computer Science and Technology Peking University Beijing China

So fur, the security of many proxy signatures has seldom been considered in a formal way and most of them cannot satisfy nonepudiation. In this work, a novel ID-based （Identity-based） proxy signature scheme is proposed by combining the proxy signature with ID-based public cryptography, and they formalize the notion of security for ID-based proxy signature schemes. And show that the security of the proposed scheme is secure. Compured with other proxy signature schemes, it does not need a secure channel. Thus, it is particularly suitable for the unreliable network computation environment. Finally, they extend proposed scheme to a proxy multi-signature which has the following advantages （1） the size of proxy multi- signature is independent of the number of delegating users; （2） the computation cost of proxy multi-signature only need two Weil paring.

关键词： proxy signature multisignature security proof

Role of gallium wetting layer in high-quality ZnO growth on sapphire (0001) substrates

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Science china(Physics,Mechanics & Astronomy) 2004年第5期47卷 612-620页

作者： ZENG Zhaoquan1,3. WANG Yong2, DU Xiaolong1, MEI Zengxia1, KONG Xianghe3. JIA Jinfeng1, XUE Qikun1 & ZHANG Ze2, 4 1. state key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, beijing 100080,{3. 2. Laboratory of Electron Microscopy, Institute of Physics, Chinese Academy of Sciences, beijing 100080,{3. 3. College of Physics and Engineering, Qufu Normal University, Qufu 273.65,{3. 4. beijing University of Technology, beijing 100022,{3. 1. state key Laboratory for Surface Physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 2. College of Physics and Engineering Qufu Normal University 273165 Qufu China 3. Laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences 100080 Beijing China 4. beijing University of Technology 100022 Beijing China

A Ga wetting layer was used to modify the surface structure of sapphire (0001) substrate to prepare high-quality ZnO film by radio frequency plasma-assisted molecule beam epitaxy. We found that this Ga layer plays a crucial role in eliminating 3. rotation domains, controlling polarity and decreasing defect density in ZnO epilayers, as demonstrated by in situ reflection high energy electron diffraction, ex situ high resolution X-ray diffraction and high resolution cross-sectional transmission electron microscopy. Zn-polar film of ZnO was determined by convergent beam electron diffraction. A Ga bilayer model is proposed to understand the effects of the Ga wetting layer on high-quality ZnO growth.

关键词： Ga wetting layer, sapphire, polarity, defect density, zinc oxide, rf-MBE, RHEED, HRXRD, TEM, CBED.

Threshold quantum secret sharing between multi-party and multi-party

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Science china(Physics,Mechanics & Astronomy) 2008年第9期51卷 1308-1315页

作者： YANG YuGuang1,2,3.& WEN QiaoYan4 1 College of Computer Science and Technology,beijing University of Technology,beijing 100124,china 2 {3. key Laboratory of Integrated Services Network,Xidian University,Xi’an 710071,china 3.{3. key Laboratory of Information security (Graduate University of Chinese Academy of Sciences),beijing 100049,china 4 {3. key Laboratory of Networking and Switching Technology,beijing University of Posts and Tele-communications,beijing 100876,china College of Computer Science and Technology Beijing University of Technology Beijing 100124 China state key Laboratory of Integrated Services Network Xidian University Xi’an 710071 China state key Laboratory of Information security (Graduate University of Chinese Academy of Sciences) Beijing 100049 China state key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

A threshold quantum secret sharing (TQSS) scheme between multi-party and multi-party was proposed using a sequence of single photons,which is useful and efficient when the parties of communication are not all present. We described the process of this TQSS scheme and discussed its security. It was shown that entan-glement is not necessary for quantum secret sharing. Moreover,the theoretic effi-ciency was improved to approach 100% as almost all the instances can be used for generating the private key,and each photon can carry one bit of information. This protocol is feasible with the present-day technique.

关键词： threshold quantum secret sharing quantum cryptography single photon multi-party and multi-party

Threshold proxy quantum signature scheme with threshold shared verification

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 1079-1088页

作者： YANG YuGuang1,3.4 & WEN QiaoYan2 1 College of Computer Science and Technology,beijing University of Technology,beijing 100124,china 2 {3. key Laboratory of Networking and Switching Technology,beijing University of Posts and Tele-communications,beijing 100876,china 3.{3. key Laboratory of Integrated Services Network,Xidian University,Xi’an 710071,china 4 {3. key Laboratory of Information {13.(Graduate University of Chinese Academy of Sciences) ,beijing 100049,china 1. College of Computer Science and Technology Beijing University of Technology Beijing 100124 China 3. state key Laboratory of Integrated Services Network Xidian University Xi’an 710071 China 4. state key Laboratory of Information security (Graduate University of Chinese Academy of Sciences) Beijing 100049 China 2. state key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

A threshold proxy quantum signature scheme with threshold shared verification is proposed. An original signer could authorize a group as its proxy signers. Then only t or more of n persons in the proxy group can generate the proxy signature on behalf of the original signer and any t-1 or fewer ones cannot do that. When the proxy signature needs to be verified,any t or more of n persons belonging to the verification group can verify the message and any t-1 or fewer ones cannot verify the validity of the proxy signature.

关键词： quantum signature threshold proxy quantum group signature threshold shared verification