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1火力发电厂实施设备状态检修的指导意见显示文摘针对现行发电设备的定期检修制度存在的主要问题,在总结国内外火力发电厂实施设备状态检修的成功经验的基础上,提出了国家电力公司系统火力发电厂实施设备状态检修的定义、目标、基本原则、组织机构及其职责、工作方式和步骤。State Power Corporation (Beijng100031,China) 2002中国电力2002,35,2:43
2Draining Tangjiashan Barrier Lake after Wenchuan Earthquake and the flood propagation after the dam break显示文摘Tangjiashan Barrier Lake is one of the largest barrier lakes caused by the Wenchuan Earthquake. Its risk analysis, emergency plan and effect of the emergency plan are introduced in this paper. The dam height of Tangjiashan Barrier Dam is about 105 m, and the reservoir storage capacity is 3.2×108 m3. When the dam broke the flood peak were estimated to be larger than 48000 m3/s, which might cause a enormous disaster to the downstream cities and residents. A discharge channel with 13 m deep and 8 m wide was drug, so that the water may flow out of the lake before the dam breaks. As a result, the drainage and risk mitigation project are successful. During the drainage process, the flood peak was about 6500 m3/s, and about 1.6×108 m3 of water was drained off and the residual reservoir capacity was only 8.97×107 m3. A new channel with average width 100 m was formed, which can bear floods of 200 years frequency. The successful experience and the collected data can be used to deal with the similar natural disasters in future.LIU Ning1, ZHANG JianXin2, LIN Wei3, CHENG WuYI4 & CHEN ZuYu5 1 Ministry of Water Resources of the People’s Republic of China, Beijing 100053, China 2 Bureau of Hydrology of the Ministry of Water Resources of the People’s Republic of China, Beijing 100053, China 3 Sichuan Hydrographic and Water Resources Survey Bureau Chengdu 610031, China 4 HydroChina Chengdu Engineering Corporation, Chengdu 610072, China 5 China Institute of Water Resources and Hydropower Research, Beijing 100044, China 2009Science China(Technological Sciences)2009,52,4:29
3Process Modeling for Heat Treatment: Current Status and Future Developments显示文摘Heat Treating is a critical manufacturing technology. This is particularly true in countries with large manufacturing industry including:; automotive, construction, transportation, and aerospace sectors. Technical advancement of the heat treating industry will be a critical component of the increasing need to remain competitive in this manufacturing sector on a global scale. ASM International has identified the development of process modeling and numerical simulation as a critical technology for the advancement of the heat treating process industry. In this paper, a selective overview of the current accomplishments and future needs of process modeling technologies in heat treatment will be provided.Tatsuo Inoue, Kiyoshi Funatani and George E. Totters 1.Department of Energy Conversion Science, Kyoto University, Kyoto, Japan 2.Nihan Parkurizing Co., Ltd., Nagoya, Japan 3.Union Carbide Corporation, Tarrytown, NY, USA 2000Journal of Shanghai Jiaotong university(Science)2000,5,1:23
4Basic Lithofacies-Succession Model for the Wumishan Cyclothems: Their Markov Chain Analysis and Regularly Vertical Stacking Patterns in the Third-Order Sequences显示文摘The Mesoproterozoic Wumishan Formation in the Jixian section ofTianjin is a succession of 3300-m-thick carbonate strata formed in a period of about 100 Ma (1310 ± 20 Ma-1207 ± 10 Ma). In this succession of strata, the carbonate metre-scale cyclic sequences belonging to peritidal type with an approximately symmetrical lithofacies succession are best developed. The wide development of 1:4 stacking patterns shows that these metre-scale cyclic se quences are genetically related to the short-eccentricity cycles, which are called the Wumishan cyclothems that could truly represent sedimentary cycles. Generally, massive and thick-bedded calcareous dolomites and dolomitic limestones of stromatolite biostromes and thrombolite bioherms constitute the central part of the Wumishan cyclothems. The lower and upper parts consist of tidal flat dolostones, sandy-muddy dolostone and the top part is composed of lagoonal facies dolo mitic shales with a paleosol cap. Therefore, an approximately symmetrical lithofacies-succession is formed. Many features such as the clear deepening and shoaling vectors of cyclothems, and all kinds of marks of fresh-water diagenesis indicate that the Wumishan cyclothems are the product of autocyclic sedimentation governed by allocyclic high-frequency sea level changes. The results of a Markov chain analysis reaffirm the existence of the lithofacies-succession model of the Wumishan cyclothems. The boundaries of the Wumishan cyclothems are marked by the instantaneous exposed punctuated surface, which leads to the discrepancy between the cyclothems and the parasequences of the sequence stratigraphy ter minology system. It is difficult to form a judgment that the time span of the Milankovitch cycles in the Precambrian is certainly equal to that of the Phanerozoic, but the regularly vertical stacking patterns of the seventh-order rhythms, sixth order cyclothems and fifth-order parasequence sets still indicate their consistency with the duration of the Milankovitch cycles in the Phanerozoic.MEI Mingxiang, MA Yongsheng and GUO Qingyin Institute of Earth Sciences and Natural Resources, China University of Geosciences, Beijing 100083 China Petrochemical Corporation (SINOPEC), Beijing 100029 2001Acta Geologica Sinica(English Edition)2001,75,4:19
5In-situ synthesis of nanoparticles via supersolubilizing micelle self-assembly显示文摘In-situ synthesis of nano-particles using the self-assembly of molten salt and super soluble micellae was proposed based on a phenomenon of super solubilization of molten salt in reverse micellae and its self-assembly when the concentration reached up to 95%(w/w).The mechanism of the self-assembly indicates that the self-assembly of molten salt occurs in a reverse micelle where a homogenous phase is established between 5%(w/w)of a surfactant with a VB value of less than 1 and a hydrocarbon spe- cies.This synthesis has some unique features,such as being free of water,highly effective deposition and narrow distribution of particle size.WANG DingCong Fushun Research Institute of Petroleum&Petrochemicals,China Petroleum&Chemical Corporation(SINOPEC),Fushun 113001, China(email:wangdingcong@hotmail.com) 2007Science China Chemistry2007,50,1:19
6Landscape ecological assessment and eco-tourism development in the South Dongting Lake Wetland, China显示文摘As an important resource and the living environment of mankind, wetland has become gradually a highlight, strongly concerned and intensively studied by scientists and sociologists. The governments in the world and the whole society have been paying more and more attention on it. The Dongting Lake of China is regarded as an internationally important wetland. For a rational development and protection of the wetland, an investigation and studied on its resources and its value to tourism in the South Dongting Lake was conducted, to create an assessment system of the ecological landscapes, and to evaluate qualitatively and quantitatively the value of wetland landscape to the eco-tourism. The results showed that the scenic value of the South Dongting Lake Wetland satisfied the criterion of AAAA grade of China national scenic attraction. The eco-tourism value of the landscape cultures in the South Dongting Lake Wetland was discussed with emphasis. It were formulated that a principle and frame of sustainable exploitation of the wetland landscapes and it was proposed as well that establishing a Wetland Park and developing eco-tourism in the South Dongting Lake. Wetland is a fragile ecosystem with low resistance to the impact of the exploitation. Thus, we must pay intensively attention to the influence of exploitation on the landscape, take the ecological risk in account to employ a right countermeasure and avoid the negative affection.HE Ping 1,2, WANG Bao-zhong 1,3 (1.Central South Forestry University, Zhuzhou 412006, China 2.China International Engineering Consulting Corporation, Beijing 100044, China 3.Nanjing University, Nanjing 210093, China 2003Journal of Environmental Sciences2003,15,2:19
7Influence of Panax ginseng Continuous Cropping on Metabolic Function of Soil Microbial Communities显示文摘Objective To investigate the influence of Panax ginseng continuous cropping on the carbon substrate metabolic activity of microbes in soils sampled from Dafang,Huangni,and Wulidi in Jilin Province,China.Methods Soil metabolisms of soil communities were characterized by community level physiological profiles using BIOLOGTM EcoPlate.Results Soils sampled from the three sites were analyzed and their metabolic activities were compared.Principal component analysis explored the significant variance in metabolic function of microbial communities in soils,though the Shannon index and the evenness index of them were similar.Futhermore,two principal components(PC1 and PC2),which contributed 67.83% and 10.78% of total variance,were extracted respectively.And also,substrates significantly correlated with PC1 and PC2 at the three sampling sites were identified.Conclusion Characteristic of soil is the primary factor influencing microbial communities,and P.ginseng continuous cropping has significant influence on microbial community.Though soil samples show similar microbial metabolic profiles,microbial communities in rhizosphere soil are changed obviously during the cultivation of P.ginseng,which would finally result in the unbalance of microbial community.Phytopathogens would gradually be the predominants in rhizosphere soil and make P.ginseng sick.YING Yi-xin1,DING Wan-long1,ZHOU Ying-qun2,LI Yong1 1.Institute of Medicinal Plant Development,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing 100193,China 2.China National Corporation of Traditional and Herbal Medicine,Beijing 100195,China 2012Chinese Herbal Medicines2012,4,4:17
8The migration fractionation: an important mechanism in the formation of condensate and waxy oil显示文摘Fault-initiated pressure release within reservoirs and the injection of external excessive dry gas may result in occurrence of oil and gas phases. Because of different partitioning coefficients of compounds in two phase flow, lower-molecular-weight components are easier to dissolve in gas phase, yielding condensates, while higher-molecular-weight components are retained in the oil phase, yielding waxy oil cumulations. The fractionation process causes extensive compositional variability in aliphatic/aromatic hydrocarbon ratios, molecular compound distributions and carbon isotope ratios that are traditionally considered to be related to the source organic matter or the thermal maturity.ZHANG ShuichangKey Laboratory for Petroleum Geochemistry, China National Petroleum Corporation, Beijing 100083, China 2000Chinese Science Bulletin2000,45,14:17
9Hierarchy modeling of subsurface palaeochannel reservoir architecture显示文摘The studies on fluvial reservoir architecture are mainly aimed at outcrop and modern deposition,but rarely at the subsurface reservoir,so there are few effective methods to predict the distribution of subsurface reservoir architectures. In this paper,taking the meandering river reservoir of Guantao formation Gudao Oilfield,Jiyang depression,Baohai Gulf Basin,East China as an example,the archi-tectural modeling method of complex meandering belt reservoir is proposed,that is hierarchy con-straint,pattern fitting and multi-dimensional interaction. Architectures of meandering river reservoir can be divided into three hierarchies: meandering channel sandbody,point bar and lateral accretion body. Different hierarchies of the quantitative architecture pattern are fitted to subsurface well data (including dynamic monitoring data) in different hierarchies through one-dimensional hole,2D profiles and plane and 3D space,which are verified by each other. And then 3D model in different hierarchies is established. At the same time,the quantificational relationship between width of active river and the scale of point bar is set up,and the scale of lateral accretion sand body and shale beddings is con-firmed with horizontal well data. The study not only has significant meaning on the development of geology,but also can improve the oilfield exploitation greatly.WU ShengHe1,YUE DaLi1,LIU JianMin2,SHU QingLin2,FAN Zheng1,3 & LI YuPeng1 1 Earth Sciences and Geoinformatics School,China University of Petroleum,Beijing 102249,China 2 SINOPEC Shengli Oilfield Co. Ltd.,Dongying 257000,China 3 Beijing Telon High-tech Corporation,Beijing 100085,China 2008Science China Earth Sciences2008,51,S2:15
10Tectonic stress field and its effect on hydrocarbon migration and accumulation in Mesozoic and Cenozoic in Kuqa depression, Tarim basin显示文摘Through rock acoustic emission experiments and structural deformation analysis, the tectonic stages in Meso-Cenozoic in the Kuqa depression of the Tarim basin are firstly divided. Then, combining with rock magnetic fabric analysis and memory information, the distribution characteristics of tectonic stress field of every tectonic stage are quantificationally resumed. At the same time, according to the distribution relation of tectonic stress field of hydrocarbon for-mation stage by the finite element numerical simulation method and the known hydrocarbon reservoirs, the effects of tectonic stress field on hydrocarbon migration and accumulation are further analyzed. The Kuqa depression has mainly experienced six tectonic movements since Mesozoic. Except that the tectonic stress field of the Early Yanshan stage (208—135 Ma) showed northeast-southwest extensional stress field where the orientation of the maximum prin-cipal compressive stress (s 1) was northwest-southeast, the others were compressive stress field where the orientations of the maximum principal compressive stress (s 1) were near north-south. Along with the closure of the paleo-Tethys ocean, the Kuqa depression in the Indosinian stage (250—208 Ma) was in strong compressive circumstance with apparently big maximum principal stress (s 1) magnitude. Due to the equilibrium adjustment of interior Eurasia, the Kuqa depression in the Early Yanshan stage (208—135 Ma) was in weak extensional circumstance with appar-ently small maximum principal stress (s 1) magnitude. From the Late Yanshan stage (135—65 Ma) on, with a series of collision events occurring at the south edge of Eurasia, the Kuqa depression was in compressive circumstance again in which the maximum principal stress (s 1) magnitude was from small to big in turn. The Late Himalayan stage (2.6—0.7 Ma) was the main tectonic deformation stage with the biggest principal compressive stress (s 1) magnitude. Tectonic stress field plays a dominant role in hydrocarbon formation, it not only forms migration channels and trap structures for hydrocarbon accumulation, but also is the main drive power for hydrocarbon migration vertically along faults.ZENG Lianbo1, TAN Chengxuan2 & ZHANG Mingli3 1. Key Laboratory for Hydrocarbon Accumulation in Petroleum University, Ministry of Education, Beijing 102249, China 2. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China 3. Institute of Exploration and Development, China Petroleum and Chemical Corporation, Beijing 100083, China 2004Science China Earth Sciences2004,47,z2:14
11盆地演化认识中的几个问题显示文摘本文论述了盆地演化认识中的几个主要问题。一是陆缘裂解过程,华南边缘传统上认为是被动裂谷边缘的一个例子,其东部沉积物记录了压实的历史,它明显不同于被动裂谷作用模式,而是显示早第三纪大规模上隆和侵蚀的特征;而且,该地区覆盖在下地壳楔形体上面,具有比周围地壳明显要高的地震速度和密度,指示岩浆底侵作用。这些证据说明,与被动裂谷作用模式相比,华南边缘与主动裂谷作用模式较为一致,它是由早第三纪华南边缘东部底下地幔柱形成的主动裂谷。另一个问题是关于页岩的浅部破裂作用机理。大多数研究者认为,微裂隙的形成需要高孔隙压力,它限于深埋、低渗透率的岩石。然而,最近从北海观察表明,在第三纪页岩中,整个盆地范围内的破裂型式从未达到大于几百米的埋藏深度。这说明泥质源岩经历了水压破裂和浅部脱水,在破裂前可能达到深埋后生作用所需要的深度,实质上渗透率的改变是由于源岩的浅部破裂作用可能根本上改变了烃类的初次运移时间和效率。Wang Chiyuen(Department of Geology and Geophysics University of California,Berkeley,CA 94720)Yang Jiaming Zhu Weilin(Exploration and Development Research Center,China National Offshore Oil Corporation,Xincheng,074010)Zheng Mingling(Scientific Research Ce 1995地学前缘1995,2,3:14
12Study on Quenching and Tempering Process of Q960 High Strength Steel for Construction Machinery显示文摘To develop the Q960 high-strength quenched and tempered steel plates for construction machinery,the effects of quenching and tempering treating regime on the microstructures and mechanical properties were investigated.The results show that the perfect austenization and fine grain size can be achieved by the optimum quenching process that is quenching temperature 900℃ and holding time 20min.Considering performance and production efficiency,the optimum tempering process parameters are found that tempering temperature 600℃ and holding time 40min.The excellent overall properties of specimens with tempered sorbite microstructure can be ultimately obtained.The yield strength is 1030MPa,tensile strength 1080MPa,percentage elongation 16.8% and the Charpy impact energy 144J at-40℃.All these indexes come up to the National Standard GB/T 16270-2009.WANG Zhao-dong 1,KANG Jian 1,LU Feng 1,2,DENG Xiang-tao 1,WANG Chao 1,WANG Guo-dong 1 (1.State Key Lab of Rolling and Automation,Northeastern University,Shenyang 110004,Liaoning,China 2.Wide Heavy Plate Project Department of Tangshan Iron and Steel Corporation,Tangshan 063000,Hebei,China) 2011Journal of Iron and Steel Research(International)2011,18,S1:13
13Fischer Plots of Wumishan Cyclothems,Precambrian Records of Third-OrderSea-Level Changes显示文摘The Mesoproterozoic Wumishan Formation ((1310 ± 20 ) Ma - (l 207 ± 10) Ma) in Jixian, Tianjin represents a succession of 3 300 meter thick carbonate strata where are the best developed stromatolite biostromes and thrombolite bioherms. These biostromes and bioherms, together with tidal-flat dolomites and muddy dolostones, form Wumishan cyclothems with approximately symmetrical faciessuccession fabrics, which belong to carbonate meter-scale cyclic sequences of peritidal type. These cyclothems are overlain by lagoon dolomitic mudstones and shales and by frequently developed paleosol layers, indicating that the boundary of Wumishan cyclothems is marked by an instantaneously-exposed punctuated surface. Viewed form the regularly vertical stacking patterns of Wumishan cyclothems in long-term sequences, 26 third-order sequences may be discerned in Wumishan Formation. These thirdorder sequences may also be incorporated into six second-order sequences. In order to study the variation range of third-order sea-level changes and the formation period of third-order sequence, 626 cyclothems are discerned in the middle and upper parts of Wumishan Formation where the outcrops are well developed. In terms of the total thickness and the formation period of Mesoproterozoic Wumishan Formation, the crust subsidence rate in the sedimentary period of Wumishan Formation is supposed to be 3 meters at each interval of 100 thousands years. Based on this assumption, Fischer plot might be designed to simulate the third-order sea-level changing pattern.Mei Mingxiang Faculty of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083 Ma Yongsheng China Petrochemical Corporation (SINOPEC), Beijing 100029 Zhou Hongrui Du Benming Luo Zhiqing Guo Qingyin Faculty of Earth Sc 2001Journal of China University of Geosciences2001,12,1:11
14Large pore volume mesoporous aluminum oxide synthesized via nano-assembly显示文摘A new nano-assembly approach has been proposed for the preparation of macropore volume mesoporous aluminum oxide supports. Secondary nano-assembly and a frame structure mechanism for large pore volume mesoporous supports have been proposed. In a primary nano-assembly supersoluble micelle,aluminum hydroxide nanoparticles were precipitated in situ in surfactants with a volume balance (VB) less than 1,followed by secondary nano-assembly in linear and cylindrical shapes. The secondary nano-assembly of cylindrical aluminum hydroxides was calcined to form nano cylindrical aluminum oxides. For the formation of macropore volume mesoporous supports,we utilized a frame structure mechanism of mesoporous support,in which the exterior surface of the carrier may not be continuous. This macropore volume support has been used for the hydrotreatment of a residual oil catalyst,which possesses the following physical characteristics:pore volume 1.8―2.7 mL·g-1,specific surface area 180―429 m2·g-1,average pore diameter 17―57 nm,average pore diameter more than 10 nm (81%―94%),porosity 87%―93%,and crush strength 7.7―25 N·mm-1.WANG DingCong Fushun Research Institute of Petroleum and Petrochemicals,China Petroleum and Chemical Corporation (SINOPEC),Fushun 113001,China 2009Science China Chemistry2009,52,12:11
15Theoretical calculation of the impact work in the alloying non-quenched and tempered steel显示文摘Coupled with hot-continuous rolling technology and based on the calculation of the finishing rolling impact work in the non-quenched and tempered Si-Mn steel, the calculations of the finishing rolling impact work in the alloying non-quenched and tempered steel with the elements of Cr, Ni, Mo, W, Cu, V, Nb and Ti are studied with the covalent electron number nA of the strongest bond in alloying phases, the smallest electron density difference ?ρ of phase interfaces, and the number of atom states σ (σ′) which keep the interface electron density continuous. The calculated results show that the finishing rolling impact work of the alloying non-quenched and tempered steel intensely depends on strengthening mechanisms. The solution strengthening, interface strengthening, precipita- tion strengthening of pearlite, and dispersion strengthening will result in the decrease of the finishing rolling impact work; the refinement strengthening, the precipitation strength- ening of V, Nb and Ti in α-Fe-C-V(Nb, Ti), and the residual austenite containing Ni on the boundary of α-Fe-C-Ni will increase the impact work; and the increments or decrements can be calculated with nA, ?ρ, σ (σ′) and weights of alloying elements. The calculation formulas of the finishing rolling impact work in this paper are intergraded with the sug- gested ones of the finishing rolling tensile strength, yield strength, and elongation of the non-quenched and tempered steel. The calculated results agree well with the measured ones.LIU Zhilin1, LIN Cheng1 & GUO Yanchang2 1. Department of Materials and Chemical Engineering, Liaoning Institute of Technology, Jinzhou 121001, China 2. The Technical Center of Benxi Iron and Steel Group Corporation, Benxi 117000, China 2006Science China(Technological Sciences)2006,49,3:11
16Research on the reconstruction method of porous media using multiple-point geostatistics显示文摘The pore structural characteristics have been the key to the studies on the mechanisms of fluids flow in porous media. With the development of experimental technology, the modern high-resolution equipments are capable of capturing pore structure images with a resolution of microns. But so far only 3D volume data of millimeter-scale rock samples can be obtained losslessly. It is necessary to explore the way of virtually reconstructing larger volume digital samples of porous media with the representative structural characteristics of the pore space. This paper proposes a reconstruction method of porous media using the structural characteristics captured by the data templates of multiple-point geostatistics. In this method, the probability of each structural characteristic of a pore space is acquired first, and then these characteristics are reproduced according to the probabilities to present the real structural characteristics in the reconstructed images. Our experimental results have shown that: (i) the deviation of LBM computed permeability respectively on the virtually reconstructed sandstone and the original sample is less than 1.2%; (ii) the reconstructed sandstone and the original sample have similar structural characteristics demonstrated by the variogram curves.ZHANG Ting 1,2,3, LI DaoLun 1,2 , LU DeTang 1,2 & YANG JiaQing 1,2 1 Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China 2 Research Center of Oil and Natural Gas, University of Science and Technology of China, Hefei 230027, China 3 The 28th Research Institute, China Electronics Technology Group Corporation, Nanjing, 210007, China 2010Science China(Physics,Mechanics & Astronomy)2010,53,1:10
17Computer Modeling: an Important Tool in Materials Processing显示文摘The development of techniques to control and use materials, especially metallic materials continues to play a key role in the technological advancement of modem day society. A variety of materials processes have been developed overtime, and are applied to design and fabricate products. Heat treatment of metallic materials has been the method of choice applied to improve mechanical properties such as strength, hardness, and toughness, as well as to improve the homogeneity of properties in materials such as corrosion resistance. The molt significant success stories in the application of materials processes involve the heat-treatment of steel. The reasons for this largely lie in the ease with which steel microstructures can be altered by controlled heating and cooling. The objective of computer modeling of materials processes is to maximize on the beneficial factors while keeping to a minimum the negating effects such as components distortion and residual stresses. Computer modeling is a powerful tool in achieving this objective in the sense that with it, the effect of parameters associated with materials processes can be analyzed systematically in order to optimize them before actual production begins.L.L Meekisho, X Chen Portland State University, P0 Box 751, Portland, Oregon 97207 USA Automated Analysis Corporation, Peoria, IL USA 2000Journal of Shanghai Jiaotong university(Science)2000,5,1:10
18Wear-resisting Oxide Films for 900℃显示文摘M.B.Peterson(Wear Sciences Corporation, Arnold, Maryland, USA)Shizhuo LI(Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China)S.F.Murray(Rensselaer Polytechnic Institute, Thoy, New York, USA) 1997Journal of Materials Science & Technology1997,13,2:9
19A formal model of fair exchange protocols显示文摘Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability, etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack. Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.QING Sihan1,2,3 & LI Gaicheng1,2,3 1. Engineering Research Center for Information Security Technology, Institute of Software, Chinese Aca- demy of Sciences, Beijing 100080, China 2. Beijing Zhongke Ansheng Corporation of Information Technology, Beijing 100080, China 3. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China 2005Science in China(Series F)2005,48,4:9
20Experimental studies on perturbed acoustic resonant spectroscopy by a small rock sample in a cylindrical cavity显示文摘A measurement system for acoustic resonant spectroscopy (ARS) is estab-lished,and the effects of resonant cavity geometry,inner perturbation samples and envi-ronmental temperature on the ARS are investigated. The ARSs of the small samples with various sizes and acoustic properties are measured. The results show that at the normal pressure,the resonant frequency decreases gradually with the increase of liquid tem-perature in the cylindrical cavity,while the resonant amplitude increases. At certain pres-sure and temperature,both the resonant frequency and the amplitude decrease greatly when there exist air bubbles inside the cavity fluid. The ARS is apparently affected by the sample porosity and the sample location in the resonant cavity. At the middle of the cavity,the resonant frequencies reach their maximum values for all of the measurement samples. The resonant frequencies of the porous rock samples are smaller than those of the com-pacted samples if other acoustic parameters are the same. As the sample is moved from the top to the middle of the cavity along its axis,the resonant amplitude increases gradu-ally for the compacted rocks while decreases for the unconsolidated rocks. Furthermore,the resonant amplitude increases firstly and then decreases if the porosity of the rock sample is relatively small. In addition,through the comparisons between the experimental and theoretical results,it is found that the effects of the acoustic parameters and sizes of the samples and the size of the cylindrical cavity on the laboratory results agree well with the theoretical ones qualitatively. These results may provide basic reference for the ex-periment study of rock acoustic properties in a low frequency using ARS.CHEN Dehua1,2,WANG Xiuming2,3,CONG Jiansheng1,XU Delong1,SONG Yanjie1 & MA Shuilong4 1. Department of Geophysics,Daqing Petroleum Institute,Daqing 163318,China 2. Institute of Acoustics,Chinese Academy of Sciences,Beijing 100080,China 3. Division of Petroleum,Australian Commonwealth Scientific and Industrial Research Organization,Bent-ley WA 6102,Australia 4. Daqing Testing and Technology Services Corporation,Daqing 163153,China 2006Science China(Physics,Mechanics & Astronomy)2006,49,6:8
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