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Identification and removal of block ambiguities in sea surface wind field with scatterometers

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Science China Earth sciences 2009年第2期52卷 242-249页

作者： CHEN KeHai1,2. XIE XueTong3.& FANG Yu4.1 South China Sea Institute of Oceanology, chinese {3. of {2., Guangzhou 5103.1, China 2.Graduate {3. of chinese {3. of {2., beijing 100049, China 3.School of Electronic Science and Engineering, National {3. of Defense Technology, Changsha 4.0073. China 4.The Institute of Remote Sensing and GIS, Peking {3., beijing 100871, China South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China Graduate university of chinese {2. of {3. Beijing China School of Electronic Science and Engineering National University of Defense Technology Changsha China The Institute of Remote Sensing and GIS Peking University Beijing China

The solution of the current wind retrieval algorithm for scatterometers has several wind vector ambi-guities, due to the bi-harmonic relationship between normalized backscattering cross section and the relative wind direction and the existence of the measurement error. In order to remove the ambiguities for a unique wind field, a circular median filter approach (CMF) is usually adopted. But under the con-dition for clustering distribution of the false ambiguities in some local areas, the CMF fails and thus engenders block ambiguities, which degrade the precision of the retrieved wind field. For such a situation, a technique of identification and removal of the block ambiguities is presented to further optimize the retrieved wind field after CMF. It is demonstrated in experiment that this technique can identify and remove most of the block ambiguities.

关键词： scatterometer block ambiguity identification and removal

Improving the accuracy of image-based forest fire recognition and spatial positioning

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Science China(Technological sciences) 2010年第S1期53卷 184-190页

作者： JIANG LiLi 1,QI QingWen 1,ZHANG An 1,GUO ChaoHui 2.& CHENG Xi 1,3.1 Institute of Geographical sciences and Natural Resources Research,chinese {2. of sciences,beijing 100101,China 2.China Center for Resources Satellite Data and Applications,beijing 100094.China 3.raduate university of chinese {2. of sciences,beijing 100049,China Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China China Center for Resources Satellite Data and Applications Beijing China Graduate university of chinese {2. of {3. Beijing China

Forest fires are frequent natural *** is necessary to explore advanced means to monitor,recognize and locate forest fires so as to establish a scientific system for the early detection,real-time positioning and quick fighting of forest *** paper mainly expounds methods and algorithms for improving accuracy and removing uncertainty in image-based forest fire recognition and spatial ***,we discuss a method of forest fire recognition in visible-light *** are four aspects to improve accuracy and remove uncertainty in fire recognition:(1)eliminating factors of interference such as road and sky with high brightness,red leaves,other colored objects and objects that are lit up at night,(2.excluding imaging for specific periods and azimuth angles for which interference phenomena repeatedly occur,(3.improving the thresholding method for determining the flame border in image processing by adjusting the threshold to the season,weather and region,and (4.integrating the visible-light image method with infrared image ***,we examine infrared-image-based methods and approaches of improving the accuracy of forest fire recognition by combining the spectrum threshold with an object feature value such as the normalized difference vegetation index and excluding factors of disturbance such as interference signals,extreme weather and high-temperature ***,a method of visible analysis to enhance the accuracy of forest fire positioning is examined and realized;the method includes decreasing the visual angle,selecting central points,selecting the largest spots,and judging the selection of fire spots according to the central *** studies are examined and the results are found to be satisfactory.

关键词： forest fire monitoring spatial positioning accuracy improvement

CMQV+:An authenticated key exchange protocol from CMQV

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Science China(Information sciences) 2012年第7期55卷 1666-1674页

作者： LI Hui 1,2.& WU ChuanKun 1 1 State Key Laboratory of Information Security,Institute of Software,chinese academy of {2.,{4. 100190,China 2.Graduate university of chinese academy of {2.,{4. 100049,China State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing China Graduate university of chinese {2. of {3. Beijing China

Ustaoglu presents a secure and efficient key exchange protocol named CMQV,based on the design rationales of HMQV and *** with the latter two protocols,on one hand,CMQV achieves high performance of HMQV,and on the other,it is proven secure in eCK model as NAXOS ***,CMQV enjoys the security proof under gap Diffie-Hellman assumption as indicated by its *** this paper,we propose a variant of CMQV,called CMQV+,which is proven secure under a weaker assumption (*** Diffie-Hellman assumption) in eCK model with random oracles while maintaining the high-performance feature of CMQV as much as possible.

关键词： key exchange eCK model trapdoor-test technique provable security CDH assumption

An efficient chiral synthesis of (R)-N-[3.acetyl-4.(2.hydroxy-3.isopropylamino-propoxy)phenyl]-butanamide with high enantioselectivity

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Science China Chemistry 2009年第8期52卷 1216-1219页

作者： WANG NaiXing1,2.& TANG XinLiang1,3.1 Technical Institute of Physics and Chemistry,chinese academy of {2.,{4. 100080,China 2.College of Chemistry and Chemical Engineering,Graduate university of chinese academy of {2.,{4. 100049,China 3.School of Chemical Engineering and Environment,{4. Institute of Technology,{4. 100081,China Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing China College of Chemistry and Chemical Engineering Graduate University of Chinese Academy of Sciences Beijing China School of Chemical Engineering and Environment Beijing Institute of Technology Beijing China

R-Enantiomer of the β-receptor antagonist N-[3.acetyl-4.(2.hydroxy-3.isopropylamino-propoxy)phenyl] butanamide with high enantioselectivity was synthesized from cheap starting materials and enantiopure chiral reagent through an efficient,convenient and practical synthetic *** product was detected by 1H NMR,13. NMR,and MS,and the enatiomeric excess was determined by chiral HPLC analysis using a chiracel AD-H column.

关键词： chiral synthesis enantioselectivity enatiomeric excess chiral HPLC analysis

The effects of shock wave and quasi-traveling wave in the mechanical impact test

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Science China(Technological sciences) 2010年第9期53卷 2535-2541页

作者： WU Mei1,5,SUN ZhongFeng2.ZHANG LuMei3.CHEN Yong1 & JI LinHong4.1 Institute of High Energy Physics,chinese {3. of {2.,{4. 100049,China 2.School of Mathematical {2.,Peking university,{4. 100871,China 3.High School of Central university for Nationalities,{4. 100081,China 4.Institute of Mechanical Design,Department of Precision Instruments and Mechanology,Tsinghua university,{4. 100084.China 5 {3. of Opto-electronics,chinese {3. of {2.,{4. 100190,China Institute of High Energy Physics Chinese Academy of Sciences School of Mathematical sciences Peking University High School of Central university for Nationalities

It is well-known that the numerical value is always larger than the measured value,amounting to many times,if we calculate the stress of the specimen in the impulse test using the NASTRAN and ANSYS (N-A) *** believe that the impact induces shock wave or quasi-traveling wave in the specimen,which can qualitatively explain the discrepancy of the two *** order to verify it,the Lax-Friedrichs (L-F) scheme is taken to simulate the transmission of shock wave and quasi-traveling wave in *** results show that the action area of the stress wave is small and the action time is very short,so the resulting stress and actual work are not *** addition,the distribution of the impact values obtained by the numerical simulation is in accordance with the trend of the measured impact values.

关键词： aerospace environment test shock wave quasi-traveling wave

Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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Science China Earth sciences 2008年第5期51卷 654-664页

作者： HU Guang1,2. JIN ZhangDong1 & ZHANG Fei3.1 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, chinese academy of {2., Xi’an 710075, China 2.Graduate {3. of the chinese academy of {2., beijing 100049, China 3.College of Resources and Environmental Science, Nanjing Agricultural {3., Nanjing 2.0095, China State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate university of the chinese {2. of {3. Beijing China College of Resources and Environmental Science Nanjing Agricultural University Nanjing China

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest China. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2. the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3. the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

Land Use of the Three Gorges Reservoir Area and the Effect on Its Landscape Pattern in the Recent 50 Years

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Wuhan university Journal of Natural sciences 2006年第4期11卷 910-914页

作者： HUANG Zhiqin 1,2.3., ZHOU Wancun 1 ,ZHOU Jieming 4., ZHU Mingcang 3.5 1. Institute of Mountain Hazards and Environment, chinese {3. of {2. , Chengdu 61004., Sichuan, China 2. Graduate {3. of chinese {3. of {2., beijing 100049, China 3. Sichuan Institute of Land Resource Management, Chengdu 61004., Sichuan , China 4. Department of Resources and Environment Science, Sichuan Normal {3. , Chengdu 610061, Sichuan, China 5. College of Information Engineering, Chengdu {3. of Technology, Chengdu 610059, Sichuan, China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu Sichuan China Graduate university of chinese {2. of {3. Beijing China Sichuan Institute of Land Resource Management Chengdu Sichuan China Department of Resources and Environment Science Sichuan Normal University Chengdu Sichuan China College of Information Engineering Chengdu University of Technology Chengdu Sichuan China

The paper makes detailed analysis on the changing processes of the main types of land use in Three Gorges Reservoir Area through the techniques of RS （Remote Sense） and GIS （Geography Information System）. Based on the theory of landscape ecology, many types of landscape pattern indexes are calculated and made correlation analysis. The results indicate that： in 1995 the ecological environment of Three Gorges Reservoir Area was the most vulnerable in the recent 50 years, but resumed in 2.02. the landscape pattern diversity index, fractal dimension index and fragmentation index has close correlation with the area of land use/cover change （LUCC）. The research also releases that the increase of the cultivated land, grassland and construction land deteriorates the landscape ecological pattern, while the increase of forest land area will help restore the landscape ecological pattern to its original state. The rapid change of grassland is an important index of the change of landscape pattern, because it has the most effect on change of landscape pattern index.

关键词： the Three Gorges Reservoir Area land use/cover change landscape pattern.

Radiometric cross-calibration of the CBERS-02.CCD camera with the TERRA MODIS

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Science China(Technological sciences) 2005年第S2期48卷 44-60页

作者： LI Xiaoying1,2.3. GU Xingfa1,3.4. MIN Xiangjun5, YU Tao1,3. FU Qiaoyan5, ZHANG Yong1,2.3.& LI Xiaowen1,3.1. State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of {3. academy of {2. and {3. Normal university, {3. 100101, China 2. Graduate university of {3. academy of {2., {3. 10003., China 3. The Center for National Spaceborne Demonstration, {3. 100101, China 4. Institut National de la Recherche Agronomique, Climat Sol Environnement, 84.14.Avignon, France 5. China Center for Resource Satellite Data and Application, {3. 10083., China State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China

For the application of the CCD camera, the most important payload on CBERS-02. the key is to provide long-term stable radiometric calibration coefficients. Although the vicarious calibration had been proved successful, it had its limitations such as test site requirement and unsuitable for historical data. Cross-calibration is one of the alternative methods, but it needs synchro surface spectrum to achieve spectral band matching factors. Our effort is to probe the influences on these factors. Simulations with a lot of surface spectrum showed that the factors changed with the viewing geometry, atmospheric condition and surface targets. However, simulating with the same viewing geometry and atmospheric condition, the spectral band matching factors of the same or similar surface targets’ spectrum acquired from different dates and different places would like to be consistent to each other within 1%―5%. Thus, the synchro measurement data can be substituted by the same or similar target from other source. Based on this method, using the MODIS as the reference, the cross-calibration was performed for CCD camera. The research demonstrated that the traditional method with single calibration site was inappropriate for CCD camera, since the offsets for its four spectral bands were not zeros. With four calibration sites, these offsets were obtained. And the camera was detected to degrade with dates based on four times of cross-calibrations.

关键词： CBERS-02 CCD camera cross-calibration the spectral band matching factors.

A two-round honest-verifier zero-knowledge protocol

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Science China(Information sciences) 2010年第5期53卷 954-963页

作者： LIU HanWu 1,2.& LIN DongDai 1 1 The State Key Laboratory of Information Security, Institute of Software, chinese academy of {2., {4. 100190, China 2.Graduate university of the chinese academy of {2., beijing 100049, China The State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Graduate university of the chinese {2. of {3.

Since the concept of zero-knowledge protocols was introduced, it has attracted a lot of attention and in turn showed significant effect on the development of cryptography, complexity theory and other areas. The round complexity of a zero-knowledge protocol is a very important efficiency consideration, and it is required to be as small as possible. Generally, it is desirable to have zero-knowledge protocols with constant numbers of rounds. Goldreich and Oren proved that only languages in BPP have one-round and two-round zero-knowledge protocols. Moreover, they also showed that only languages in BPP have one-round honest-verifier zero-knowledge protocols. The notion of honest-verifier zero-knowledge protocols is highly non-trivial and fascinating itself, and has many other uses. Thus, the problem as to whether there exist two-round honest-verifier zero-knowledge protocols becomes an important open problem. In this paper, we introduce a new simulation technique and present a two-round honest-verifier zero-knowledge protocol for any language in N P under a standard complexity assumption based on this technique.

关键词： proof system argument system zero-knowledge witness indistinguishability black-box one-way permutation commitment scheme zap