检索结果-南通市图书馆

Science china(Technological Sciences) 2010年第3期53卷 782-788页

作者： XU ShuXue&MA GuoYuan beijing university of technology,beijing 100124,china beijing university of technology Beijing China

Ejector can utilize high pressure energy from liquid mechanism,it can be used in heat pump system coupled with economized vapor injection(EVI)scroll *** running under low temperature conditions,the performance of the EVI system with ejector can be improved *** this paper,the design method of the heat pump system with ejector is presented,and the process for designing the heat pump with ejector(EVIe)was *** prototype heat pump was designed under the condition of the evaporation temperature of -20oC,and an experimental setup was established to test the *** measured results demonstrated that the heating EER(energy efficiency ratio)of the EVIe could reach about 4%higher than that of the system without the ejector when the heating capacity remained nearly *** design method is helpful to development of a heat pump system coupled with scroll compressor and ejector.

关键词： heat pump ejector design scroll compressor

Quick image-processing method of UAV without control points data in earthquake disaster area

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中国有色金属学会会刊：英文版 2011年第S3期21卷 523-528页

作者： LI Chang-chun1, ZHANG Guang-sheng1, LEI Tian-jie2, 3, GONG A-du2, 3 1. School of Surveying & Land information Engineering, Henan Polytechnic university, Jiaozuo 454000, china 2. Key Laboratory of Environmental Change and natural Disaster, Ministry of Education, beijing Normal university, beijing 100875, china 3. Ministry of Civil Affairs/Ministry of Education of china Academy of Disaster Reduction and Emergency Management, beijing Normal university, beijing 100875, china School of Surveying & Land information Engineering Henan Polytechnic University Jiaozuo 454000 China Key Laboratory of Environmental Change and natural Disaster Ministry of Education Beijing Normal University Beijing 100875 China Ministry of Civil Affairs/Ministry of Education of china Academy of Disaster Reduction and Emergency Management Beijing Normal University Beijing 100875 China

The methods of unmanned aerial vehicles images splicing rapidly and rectifying without control points data, only using auxiliary data recorded by unmanned aerial vehicle (UAV) system, were researched. Two algorithms were proposed, including UAV images auto- splicing rapidly after image blocking and UAV images rectifying based on pseudo center points of auxiliary data. When SIFT algorithm for UAV images splicing is applied, the accuracy is very high, but the efficiency is very low. The splicing efficiency is improved greatly based on SIFT algorithm after image blocking. The results show that rectifying accuracy is very high and has no visual dislocation when pseudo center points of auxiliary data is applied.

关键词： unmanned aerial vehicles SIFT algorithm blocking quickly splicing rectification

Geochemical characteristics and origin of gases from the Upper,Lower Paleozoic and the Mesozoic reservoirs in the Ordos Basin,china

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Science china Earth Sciences 2008年第S1期51卷 183-194页

作者： HU AnPing 1 ,Li Jian 2 ,ZHANG WenZheng 3 ,LI ZhiSheng 2 ,HOU Lu 4 &LIU QuanYou 5 1 Department of Earth Sciences,Zhejiang university,Hangzhou 310027,china 2 Langfang Branch,Reasearch Institute of petroleum Exploration and Development,Petrochina,Langfang 065007,china 3 Institute of Exploration and Development,Petrochina Changqing Oilfield Company,Xi’an 710021,china 4 university of petroleum,beijing102249,china 5 Petrochina Research Institute of petroleum Exploration and Development,beijing 100083,china Department of Earth Sciences Zhejiang University Hangzhou China Langfang Branch Reasearch Institute of Petroleum Exploration and Development PetroChina Langfang China Institute of Exploration and Development PetroChina Changqing Oilfield Company Xi’an China university of petroleum Beijing China Petrochina Research Institute of petroleum Exploration and Development Beijing China

The Ordos Basin,the second largest sedimentary basin in china,contains the broad distribution of natural gas *** far,several giant gas fields have been discovered in the Upper and Lower Paleozoic in this basin,each having over 1000×10 8 m 3 of proven gas reserves,and several gas pools have also been discovered in the *** paper collected the data of natural gases and elucidated the geochemical characteristics of gases from different reservoirs,and then discussed their *** hydrocarbons preserved in the Upper Paleozoic,the elevatedδ13C values of methane,ethane and propane indicate that the gases would be mainly coal-formed gases;the singular reversal in the stable carbon isotopes of gaseous alkanes suggests the mixed gases from humic sources with different *** the Lower Paleozoic,theδ13C 1 values are mostly similar with those in the Upper Paleozoic,but theδ13C 2 andδ13C 3 values are slightly lighter,suggesting that the gases would be mixing of coal-type gases as a main member and oil-type *** are multiple reversals in carbon isotopes for gaseous alkanes,especially abnormal reversal for methane and ethane(i.e.δ13C 1 >δ13C 2 ),inferring that gases would be mixed between high-mature coal-formed gases and oil-type *** the Mesozoic,the δ13Cvalues for gaseous alkanes are enriched in 12C,indicating that the gases are mainly derived from sapropelic sources;the carbon isotopic reversal for propane and butane in the Mesozoic is caused by microbial oxidation and mixing of gases from sapropelic sources with different *** contrast to the Upper Paleozoic gases,the Mesozoic gases are characterized by heavier carbon isotopes of iso-butane than normal butane,which may be caused by gases generated from different kerogen types. Finally,according toδ13C 1 -Ro relationship and extremely low total organic carbon contents,the Low Paleozoic gases would not be generated from the Ordovician source as a main gas source,bycontrast, the Upper Pale

关键词： Ordos Basin natural gas chemical composition carbon isotope genesis

Distribution of Nb atom in the TiAl+Nb system

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Rare Metals 2001年第1期20卷 5-12页

作者： Xiaodong Ni, Xidong Hui, Guoliang Chen (Applied Science School, university of Science and technology beijing, beijing 100083, china State Key Laboratory for Advanced Metals and Materials, university of Science and technology beijing, china) Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.

关键词： Computer simulation Intermetallics Superlattices Ternary systems

The precipitation and effect of nano nitrides in HSLC steel

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Science china(Technological Sciences) 2008年第7期51卷 989-998页

作者： FU Jie1, LIU YangChun1,2 & WU HuaJie1,3 1 School of Metallurgical and Ecological Engineering, university of Science and technology beijing, beijing 100083, china 2 Shougang technology Research Institute, Shougang (Group) Corporation, beijing 100041, china 3 Metallurgical Engineering Research Institute, university of Science and technology beijing, beijing 100083, china School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing China Shougang technology Research Institute Shougang (Group) Corporation Beijing China Metallurgical Engineering Research Institute University of Science and Technology Beijing Beijing China

The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

关键词： thin slab casting and rolling high strength low carbon steel AlN nano nitride precipitation strengthening

Analysis of forest backscattering characteristics based on polarization coherence tomography

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Science china(Technological Sciences) 2010年第S1期53卷 166-175页

作者： LUO HuanMin 1,LI XiaoWen 1,2,CHEN ErXue 3,CHENG Jian 4 & CAO ChunXiang 21 Institute of Geo-Spatial information Science and technology,university of Electronic Science and technology of china,Chengdu 610054,china 2 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 3Institute of Forest resources information Technique of Chinese Academy of Forestry,beijing 100091,china 4 School of Electronic Engineering,university of Electronic Science and technology of china,Chengdu 610054,china Institute of Geo-Spatial information Science and technology University of Electronic Science and Technology of China Chengdu 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 China Institute of Forest resources information Technique of Chinese Academy of Forestry Beijing China School of Electronic Engineering University of Electronic Science and Technology of China Chengdu China

It is difficult to make an inventory of vertical profiles of forest structure parameters in field ***,analysis and understanding of forest backscattering characteristics contribute to estimation and detection of forest vertical structure because of the close relationships between backscattering characteristics and structure *** vertical structure function in the complex interferometric coherence definition,which represents the vertical variation of microwave scattering with the penetration depth at a point in the 2-D radar image and can be used to analyze the forest backscattering characteristics,can be reconstructed from polarization coherence tomography(PCT).Based on PCT,the paper analyzes the forest backscattering characteristics and explores the inherent relationship between the result of PCT and the forest structure parameters from numerical simulation of Random Volume over Ground model(RVoG),Polarimetric SAR interferometry(PolInSAR)simulation of forest scene and PolInSAR data at L-band of the test site ***,the effects of the extinction coefficient and surface-to-volume scattering ratio in RVoG model on vertical backscattering characteristics are analyzed by means of numerical ***,by applying PCT to L-band POLInSAR simulations of forest scene,different variations of vertical backscattering due to different extinction coefficients and the ratios of surface-to-volume scattering resulting from different polarizations,forest types and densities are displayed and *** a concept of relative average backscattering intensity is presented,and the factors which affect its vertical distribution are also *** results show that there is high sensitivity of the vertical distribution of forest relative average backscattering intensity to the polarization,forest type and ***,based on repeat pass DLR E-SAR L-band airborne POLInSAR data,the capability of PCT technology for detection

关键词： backscattering characteristic POLInSAR PCT vertical structure function

Theoretical research progress in new-generation Internet architecture

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Science in china(Series F) 2008年第11期51卷 1634-1660页

作者： WU JianPing1,2,3,LIU Ying2,3 & WU Qian2,3 1 Department of Computer Science,Tsinghua university,beijing 100084,china 2 Network Research Center,Tsinghua university,beijing 100084,china 3 Tsinghua National Laboratory for information Science and technology(TNList) ,beijing 100084,china Department of Computer Science Tsinghua University Beijing China Network Research Center Tsinghua University Beijing China Tsinghua National Laboratory for information Science and technology (TNList) Beijing China

Internet has become the most important information infrastructure supporting modern socio-economic development, social progress and technological Innovation. Invented 30 years ago, today Internet is facing increasingly severe technical challenges. This paper introduces the progress of the major international newgeneration Internet research plans; analyzes its basic characteristics and the principal contradictions during the development; detsiledly introduces the research carried out by 973 Project ＂Research of Future Internet Architecture＂ on the key scientific issues of new-generation Internet architecture and its latest research results; and looks to the future of the research-focus faced with the new situations of the basic research of new-generation Internet architecture as well as the new demands of innovative applications on Internet architecture.

关键词： new-generation Internet network architecture multi-dimension scalability

Research and application of water jet technology in well completion and stimulation in china

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petroleum Science 2010年第2期7卷 239-244页

作者： Li Gensheng Huang Zhongwei Tian Shouceng Shen Zhonghou State Key Laboratory of petroleum resource and Prospecting china university of petroleum Beijing 102249 China

In recent years, rapid progress in the use of high pressure water jets （HPWJ） has been made in oil and gas well drilling, completion, and stimulation; and good results have been achieved in field applications. Advances in technologies and developments of well completion and stimulation with hydrajet are reviewed in this paper. Experiments were conducted to study the characteristics of abrasive water jetting and to optimize jet parameters, which can provide methods for the well completion and hydrajet fracturing. Deep-penetrating hydrajet perforating can create a 2-3 m clean hole with a diameter of 20-35 mm. Multilayer hydrajet fracturing is a process whereby multiple layers are stimulated in a single run without using mechanical packers, thereby reducing operation procedure and risk. Multilateral radial wells can be drilled using hydraulic jetting up to 100 m in length. The technique to remove sand particles and plugs with rotating self-resonating cavitating water jets in horizontal wellbores has been developed and oilfield-tested, which shows promising, cost effective prospects.

关键词： Water jet abrasive jet well completion perforation stimulation horizontal drilling with hydrajet

Building a next generation Internet with source address validation architecture

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Science in china(Series F) 2008年第11期51卷 1681-1691页

作者： WU JianPing1,3,REN Gang1,3 & LI Xing2,3 1 Department of Computer Science,Tsinghua university,beijing 100084,china 2 Department of Electronic Engineering,Tsinghua university,beijing 100084,china 3 Tsinghua National Laboratory for information Science and technology(TNList) ,beijing 100084,china Department of Computer Science Tsinghua University Beijing China Tsinghua National Laboratory for information Science and technology (TNList) Beijing China Department of Electronic Engineering Tsinghua University Beijing China

The IP packet forwarding of current Internet is mainly destination based. In the forwarding process, the source IP address is not checked in most *** causes serious security, management and accounting problems. Based on the drastically increased IPv6 address space, a ＂source address validation architecture＂（SAVA） is proposed in this paper, which can guarantee that every packet received and forwarded holds an authenticated source IP address. The design goals of the architecture are lightweight, loose coupling, ＂multi-fence support＂ and incremental deployment. This paper discusses the design and implementation for the architecture, including inter-AS, intra-AS and local subnet. The performance and scalability of SAVA are described. This architecture is deployed into the CNGI-CERNET2 infrastructure a large-scale native IPv6 backbone network of the china Next Generation Internet project. We believe that the SAVA will help the transition to a new, more secure and dependable Internet.

关键词： IP source address validation network architecture network security

Real-time reliability prediction for dynamic systems with both deteriorating and unreliable components

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Science in china(Series F) 2009年第11期52卷 2234-2246页

作者： XU ZhengGuo1,2, JI YinDong2,3 & ZHOU DongHua1,2? 1 Department of Automation, Tsinghua university, beijing 100084, china 2 Tsinghua National Laboratory for information Science and technology, Tsinghua university, beijing 100084, china 3 Research Institute of information technology (RIIT), Tsinghua university, beijing 100084, china Department of Automation Tsinghua University Beijing China Tsinghua National Laboratory for information Science and technology Tsinghua University Beijing China Research Institute of information technology (RIIT) Tsinghua University Beijing China

As an important technology for predictive maintenance, failure prognosis has attracted more and more attentions in recent years. Real-time reliability prediction is one effective solution to failure prognosis. Considering a dynamic system that is composed of normal, deteriorating and unreliable components, this paper proposes an integrated approach to perform real-time reliability prediction for such a class of systems. For a deteriorating component, the degradation is modeled by a time-varying fault process which is a linear or approximately linear function of time. The behavior of an unreliable component is described by a random variable which has two possible values corresponding to the operating and malfunction conditions of this component. The whole proposed approach contains three algorithms. A modified interacting multiple model particle filter is adopted to estimate the dynamic system＇s state variables and the unmeasurable time-varying fault. An exponential smoothing algorithm named the Holt＇s method is used to predict the fault process. In the end, the system＇s reliability is predicted in real time by use of the Monte Carlo strategy. The proposed approach can effectively predict the impending failure of a dynamic system, which is verified by computer simulations based on a three-vessel water tank system.

关键词： reliability failure prognostics dynamic systems fault prediction particle filtering interacting multiple model exponential smoothing,predictive maintenance