检索结果-南通市图书馆

Journal of Thermal science 2003年第1期12卷 1-9页

作者： Jingyi Cheninstitute of Engineering Thermophysics, chinese academy of sciences, beijing 100080, china institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China

This paper reviews the development in the research of flow instability and its control over the recent ten or more years. This development was largely stimulated by the novel idea of active control of the aerodynamic instability in compressors. Three topics are covered in the paper, which appeared as the major themes towards the goal of stability enhancement. The first topic is the pre-stall behavior of rotating stall, which plays a vital role in designing the control scheme and discovering the convenient route to find the causal factors of flow disturbances potentially leading to stall. The second topic is the mechanism of blade passage flow during stall and its inception, which is the basic knowledge needed to manipulate the blade design for the stability improvement and eventually to predict the unsteady performance of the compressor system. The third topic is the recent trend of the control strategy based on the learning of active vs. passive methods. To introduce to the discussion of these topics, a brief description of the history of the recent development is given at the beginning of the paper. In discussing each topic, future works are also highlighted to enhance the further development of this long-standing problem in turbomachinery research and application.

关键词： compressors rotating stall pre-stall active/passive control wavelet.

Constructing Noise Filter by Dynamical Decoupling

在线全文

学校读者我要写书评

暂无评论

Constructing Noise Filter by Dynamical Decoupling

Quantitative estimation of the shrub canopy LAI from atmosphere-corrected HJ-1 CCD data in Mu Us sandland

第三十届中国控制会议

作者： PAN Yu,XI Zai-Rong,CUI Wei Key Laboratory of systems and Control,institute of systems science,academy of mathematics and systems science,chinese academy of sciences,beijing 100190,people''s republic of china

＜正＞Dynamical decoupling（DD） emerges as a promising tool to suppress decoherence of quantum systems by eliminating the system-environment *** investigate its power in combating pure dephasing of a qubit under random classical noise. Interestingly,the decoherence rate can be viewed as the interplay between noise spectrum and a controllable filter *** specifically,the filter function is determined by the DD sequence we *** we take Uhrig DD（UDD） as a benchmark sequence to illustrate the filtering *** find that UDD sequence works as a perfect dynamical filter for low-frequency *** spectrum with hard cutoff,UDD increases the performance order by order with linearly increased number of pulses. However,for noise spectrum with soft cutoff,the required pulse number grows exponentially.

关键词： Dynamical Decoupling Filter UDD

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

science china Earth sciences 2010年第S1期53卷 26-33页

作者： CHEN Wei1,2,CAO ChunXiang1,HE Qisheng1,2,GUO HuaDong3,ZHANG Hao1,2,li RenQiang4,ZHENG sheng1,2,XU Min1,2,GAO MengXu1,2,ZHAO Jian1,2,li sha1,NI Xiliang1,2,JIA HuiCong1,JI Wei1,TIAN Rong1,2,liU Cheng1,2,ZHAO YuXing5 & li JingLu6 1 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 2 Graduate University of chinese academy of sciences,beijing 100049,china 3 Center for Earth Observation and Digital Earth,chinese academy of sciences,beijing 100190,china 4 china Key Laboratory of Ecological Network Observation and Modeling,institute of Geographical sciences and Natural Resources Research,chinese academy of sciences,beijing 100101,china 5 Ordos Forestry sand Control science institute,Dongsheng 017000,china 6 Inner Mongolia Biomass Thermoelectricity limited Company,Wushen 017300,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 Graduate University of chinese academy of sciences Beijing China Center for Earth Observation and Digital Earth Chinese Academy of Sciences Beijing China china Key Laboratory of Ecological Network Observation and Modeling Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Ordos Forestry sand Control science institute Dongsheng China Inner Mongolia Biomass Thermoelectricity limited Company Wushen China

The leaf area index(LAI) is an important ecological parameter that characterizes the interface between vegetation canopy and the *** addition,it is used by most process-oriented ecosystem *** paper investigates the potential of HJ-1 CCD data combined with linear spectral unmixing and an inverted geometric-optical model for the retrieval of the shrub LAI in Wushen Banner of Inner Mongolia in the Mu Us ***(Moderate Resolution Atmospheric Radiance and Transmittance Model) was used for atmospheric *** was extracted using the threshold of the normalized difference vegetation index,with which water bodies and farmland were separated,in combination with a vegetation map of the people's republic of china(1:1000000).Using the geometric-optical model,we derive the per-pixel reflectance as a simple linear combination of two components,namely sunlit background and *** fraction of sunlit background is related to the shrub *** the support of HJ-1 CCD data,we employ linear spectral unmixing to obtain the fraction of sunlit background in an atmospherically corrected HJ *** addition,we use the measured shrub canopy structural parameters for shrub communities to invert the geometric-optical model and retrieve the pixel-based shrub *** total,18 sample plots collected in Wushen Banner of Inner Mongolia are used for *** results of the shrub LAI show good agreement with R2 of 0.817 and a root-mean-squared error of 0.173.

关键词： shrub leaf area index inversion HJ-1 data geometric-optical model MODTRAN Mu Us sandland

Glacier changes during the last forty years in the Tarim Interior River basin,northwest china

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2009年第6期19卷 727-732页

作者： Donghui shangguana, shiyin liu a,b, Yongjian Dinga, lianfu Dinga, Junli Xua, li Jing a a state Key Laboratory of Cryospheric science, Cold & Arid Regions Environmental & Engineering Research institute, chinese academy of sciences, Lanzhou 730000, china b institute for Tibetan Plateau Research, chinese academy of sciences, beijing 100029, china state Key Laboratory of Cryospheric science Cold & Arid Regions Environmental & Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China institute for Tibetan Plateau Research Chinese Academy of Sciences Beijing 100029 China

By comparing digitized glacier outlines from the chinese Glacier Inventory (CGI) during the 1960s-1970s and Landsat Enhance Thematic Mapper (ETM+) images from 1999 to 2001, we investigated changes for about 7665 alpine glaciers among 11665 glaciers in seven sub-basins of the Tarim Interior River basin (TIRB). The results showed that the total glacier area was reduced by 3.3% from the 1960s/ 1970s to 1999/2001 and area losses for 1-5 km2 glaciers accounted for 48.3% of the total glacier area loss in the TIRB. However, the glacier area reductions varied from 0.7% to 7.9% among the seven sub-basins of the TIRB during the study period. The glacier area changing with altitude showed that the maximum contribution of area shrinkage occurred at 4900-5400 m. Data from 25 meteorological stations in the TIRB showed increases in both the annual mean air temperature and annual precipitation during 1960-2000. This indicates that the glacier shrinkage in the TIRB over the last 40 years was largely due to regional climate warming that enhanced glacier ablation and overcame the effects of increased precipitation on the glacier mass balance.

关键词： Glacier change Climate change Remote sensing

Digitally determining forest inventory units with an ecological classification system

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Technological sciences) 2006年第z1期49卷 118-127页

作者： TANG Una, WANG Qingli, Guofan shao, DAI limin, WANG shunzhong, li Xiufen & XU Dong institute of Applied Ecology, chinese academy of sciences, shenyang 110016, china Graduate University of chinese academy of sciences, beijing 100101, china Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, UsA institute of Applied Ecology Chinese Academy of Sciences

Management-level forest resource data in china were obtained with a combination of two forest inventories. However, inconsistencies in the spatial attributes of forest data vary between the two inventory types and between two inventories of the same type. The inconsistencies make it inconvenient for long-term forest management planning with digital technologies. Ecological Land Types (ELTs) and Ecological Land Type Phases (ELTPs) have been mapped in selected forestry regions in northeast china, where important forest industries are located. The boundaries of ELTs are determined by geomorphic conditions, which are quantified by Digital Elevation Models (DEM); ELTPs are classified by overlaying ELTs with forest vegetation data layers that are obtained with both remotely sensed and ground data. The ELTPs represent the divisions of land in terms of both natural and human-induced forest conditions, and therefore they are reliable units for forest inventories and management. This paper introduces a case study for digitally determining forest inventory units in Benxi City, liaoning Province, northeast china. The general objective of the study was to explain how a compatible forest inventory system should be designed and why the compatible forest inventory system was significant to digital forestry in china.

关键词： forest inventory, ecological classification, ELT mapping, ELTP mapping, geographic information systems, forest management.

Variations of δ^(18)O in precipitation from the Muztagata Glacier, East Pamirs

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2006年第1期49卷 36-42页

作者： li Zhen1, YAO Tandong1,2, TIAN lide1,2, XU Baiqing1,2 & Wu Guangjian2 1. Key Laboratory of Cryosphere and Environment, Jointly Established by Cold and Arid Regions Environmental and Engi-neering Research institute and institute of Tibetan Plateau Research, chinese academy of sciences and chinese academy of Meteorological sciences, china Meteorological Administration, CAs, Lanzhou 730000, china 2. Laboratory of Environment and Process on Tibetan Plateau, institute of Tibetan Plateau Research, chinese academy of sciences, beijing 100085, china Key Laboratory of Cryosphere and Environment Jointly Established by Cold and Arid Regions Environmental and Engineering Research Institute and Institute of Tibetan Plateau Research Chinese Academy of Sciences and Chinese Academy of Meteorological Sciences China Meteorological Administration Lanzhou China Laboratory of Environment and Process on Tibetan Plateau Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

Expeditions to Muztagata (in the eastern Pamirs) during the summer seasons of2002 and 2003 collected precipitation samples and measured their oxygen isotopes. The δ^(18)O inprecipitation displays a wide range, varying from -17.40per thousand to +1.33per thousand inJune—september 2002 and from -22.31per thousand to +4.59per thousand in May—August 2003. Theδ^(18)O in precipitation correlates with the initial temperature of precipitation during theobserving periods. The positive correlation between δ^(18)O and temperature suggests that δ^(18)Ocan be used as an indicator of temperature in this region. The δ^(18)O values in fresh-snow samplescollected from two snow events at different elevations on the Muztagata Glacier show a strong''altitude effect'', with a ratio of nearly -0.40per thousand per 100 m from 5500 m to 7450 m.

关键词： Muztagata, δ18O, temperature, altitude effect.

siO/CNTs:A new anode composition for lithium-ion battery

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2009年第12期52卷 2047-2050页

作者： REN YuRong1,2,3?,QU MeiZhen1 & YU ZuoLong1 1 Chengdu institute of Organic Chemistry,chinese academy of sciences,Chengdu 610041,china 2 College of Chemistry,Jilin Normal University,siping 136000,china 3 Graduate University of chinese academy of sciences,beijing 100039,china Chengdu institute of Organic Chemistry Chinese Academy of Sciences Chengdu China College of Chemistry Jilin Normal University Siping China Graduate University of chinese academy of sciences Beijing China

A new anode composition siO/CNTs (carbon nanotubes) has been prepared by chemical vapor deposition (CVD) method. The results of scanning electron microscopy (sEM) confirm that CNTs deposit on small siO particles,form a cage,and enwrap siO particles tightly. siO/CNTs anode composition exhibits an initial discharge and charge capacity of 1171 and 789 mAh/g,and maintains a reversible capacity of 500 mAh/g after 80 cycles. The improvement of the cyclic performance for siO/CNTs composition is related to the maintaining of the electric network during cycling,which benefits from a tight contact between CNTs and siO particles.

关键词： siO/CNTs CVD composition anode li-ion battery

Relationships between δ ^(18)O in summer precipitation and temperature and moisture trajectories at Muztagata, western china

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2006年第1期49卷 27-35页

作者： YU Wusheng1,2, YAO Tandong1,2, TIAN lide1,2, li Zhen2, sUN Weizhen2 & WANG Yu2 1. Laboratory of Environment and Process on Tibetan Plateau, institute of Tibetan Plateau Research, chinese academy of sciences, beijing 100085, china 2. Key Laboratory of Cryosphere and Environment, Jointly Established by Cold and Arid Regions Environmental and Engi-neering Research institute and institute of Tibetan Plateau Research, chinese academy of sciences and chinese academy of Meteorological sciences, china Meteorological Administration, CAs, Lanzhou 730000, china Laboratory of Environment and Process on Tibetan Plateau Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China Key Laboratory of Cryosphere and Environment Jointly Established by Cold and Arid Regions Environmental and Engineering Research Institute and Institute of Tibetan Plateau Research Chinese Academy of Sciences and Chinese Academy of Meteorological Sciences China Meteorological Administration Lanzhou China

Based on summer observations of stable isotope of precipitation at Muztagata, western china, during 2002―2003, this paper presents the relationship between δ 18O in precipitation and air temperature, and discusses the effect of moisture transport on δ 18O in precipitation. Results show that air temperature correlates positively with δ 18O in precipitation, and the temperature effect controls the δ 18O of precipitation in this area. The Muztagata region exhibits high δ 18O values in summer precipi-tation, similar to those shown at stations in adjacent regions. According to the results of our model set up to trace the moisture trajectories, the westerlies and local moisture circulation contribute to varia-tions of oxygen isotopes in precipitation. In addition, the impacts of the moisture transport distance, the moisture transport level, and the incursion of the polar air mass also influence the variations of δ 18O in precipitation. The moisture origins and transport mechanisms also contribute to the variation of δ 18O in precipitation at Muztagata.

关键词： Muztagata, δ18O, precipitation, temperature, moisture transport.

synthesis,characterization and properties of biodegradable poly（butylene succinate）-co-poly（propylene glycol） segmented block copolyesters

在线全文

学校读者我要写书评

暂无评论

Synthesis,characterization and properties of biodegradable p...