检索结果-南通市图书馆

Multiple time scale evaluation of the energy balance during the maize growing season,and a new reason for energy imbalance

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 Earth Sciences 2009年第1期52卷 108-117页

作者： GUO JianXia1,2.BIAN LinGen3 & DAI YongJiu2.1 Meteorological Observation center of china Meteorological {2.,beijing 100081,china 2.State Key Laboratory of Remote Sensing Science,School of Geography and Remote Sensing Science,beijing Normal University,beijing 100875,china 3 Chinese Academy of Meteorological Sciences,beijing 100081,china Meteorological Observation center of china Meteorological {2. Beijing 100081 China State Key Laboratory of Remote Sensing Science School of Geography and Remote Sensing Science Beijing Normal University Beijing 100875 China

Energy imbalance is a common problem associated with the measurement of surface energy using the eddy covariance *** the evaluation of the energy balance,people usually pay more attention to the statistical result that the effective energy(the sum of sensible and latent heat) is systematically lower than the available energy(the difference of net radiation and ground heat flux).However,little attention has been paid to the existence of the reversed situation when the effective energy is larger than the available energy or their contribution to the overall energy closure *** this paper,based on the analysis of the energy balance on multiple time scales across the maize growth season,we conclude that the non-synchronization of energy components is the main reason for the existence of the reversed *** shifting the phase of the effective energy components half an hour ahead,the rates of energy closure over all time scales are improved and dramatically reduce the number of the half-hourly samples when the energy ratio exceeds 1 or is below *** to the characteristics of the energy distribution and transformation over multiple time scales,latent heat is always the main type of energy cost,and the residual of the energy balance increases with the growth of the maize plant surpassing the sensible heat for seventy *** is suggested that the heat storage and photosynthetic energy play an important role in the energy balance during the growing period of maize.

关键词： maize energy balance multiple time scale energy hysteresis

Solving the input data in error correc-tion of optical fabrication by finite Fourier coefficient algorithm

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2006年第1期49卷 50-60页

作者： CHENG Haobo1,2. SUN Guozheng3 & FENG Zhijing2.1. Department of Optical Engineering, beijing Institute of Technology, beijing 100081, {2. 2. Department of Precision Instruments and Mechanology, Tsinghua University, beijing 100084, {2. 3. {2. North Industries Group Corporation, beijing 100089, {2. 1. Department of Optical Engineering Beijing Institute of Technology Beijing 100081 China 2. Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China 3. china North Industries Group Corporation Beijing 100089 China

A free-form lens (FFL) is a special surface that is difficult to be fabricated. FFL are usually fabricated by computer-controlled optical surfacing (CCOS) technique. During CCOS, the material removal amount is determined by the unit removal function (URF) convoluting with the input data――the dwell time. When the removal amount and the URF are known, how to solve the input data involves the special algorithm――deconvolution. Usually, the input data are solved by virtue of low pass filter or iterative methods. However, an approximation solution would destroy the machining stability nec-essary to perform precisely CCOS. In this paper, to solve the input data, a new method that is based on the finite Fourier coefficient is put forward. It can give a continuous and accurate solution for fabricating choice. Several parameters are simulated, which influ-ence the process of CCOS, and evaluating on the effect of the method is also carried out. Experimental results verify that this method is suitable for guiding the manufacturing of high precision FFL.

关键词： optical fabrication, computer controlled optical surfacing, free-form lens, finite Fourier coefficient, error correction.

Progress in china’s climate change study in the 2.th century

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2004年第S1期 5-13页

作者： ZHAI Panmao1,2. CHAO Qingchen1,2. ZOU Xukai1,2.1. Laboratory for Climate Studies, china Meteorological administration, {2., china 2. national Climate center, china Meteorological administration, {2., china)

Studies on the 2.th century climate change in china have revealed that under the background of global warming over the past century, climate in china has also experienced significant change with mean annual temperature increased by about 0.5 oC. More reliable results for the latter part of the 2.th century indicate that the largest warming occurred in Northwest china, North china and Northeast china, and the warming in winter is most significant. Although no obvious increase or decrease trends were detected for mean precipitation over china in the past half century, regional differences are very distinct. In the middle and lower reaches of the Yangtze River, precipitation increased, while that in the Yellow River Basin markedly decreased. Studies suggest that climate change in china seems to be related not only with the internal factors such as ENSO, PDO, and the others, but also with the anthropogenic effects such as greenhouse gas emissions, and land use. The future climate change studies in china seem to be important in narrowing understanding the nature of china's climate change and its main causes, since it is significant for projection and for impact assessment of climate change in the future.

关键词： th century climate change china

Absolute radiometric calibration of CBERS-02.IRMSS thermal band

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) 2005年第S2期48卷 72-90页

作者： ZHANG Yong1,2.3, GU Xingfa1,3,4, YU Tao1,3, ZHANG Yuxiang5, CHEN Liangfu1,3, LI Xiaoying1,2.3, LI Xiaowen1,3 & HE Liming6 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, {2. 2. Graduate University of Chinese Academy of Sciences, beijing 100039, {2. 3. The center for national Spaceborne Demonstration, beijing 100101, {2. 4. Institut national de la Recherche Agronomique, Climat Sol Environnement, 84914 Avignon, France 5. national Satellite Meteorological center, {12., {2. 6. State Environmental Protection administration, beijing 10002., {2. Chinese Acad Sci Inst Remote Sensing Applicat State Key Lab Remote Sensing Sci Beijing 100101 Peoples R China beijing Normal Univ State Key Lab Remote Sensing Sci Beijing 100101 Peoples R China Chinese Acad Sci Grad Univ Beijing 100039 Peoples R China Ctr Natl Spaceborne Demonstrat Beijing 100101 Peoples R China INRA F-84914 Avignon France Natl Satellite Meteorol Ctr Beijing 100081 Peoples R China State Environm Protect Adm Beijing 100029 Peoples R China

Based on the laboratory calibration before launch of CBERS-02.IRMSS thermal infrared channel, the onboard blackbody calibration, the radiometric cross- calibration against TERRA MODIS corresponding channel and the in-flight field calibration at Lake Qinghai: water surface radiometric calibration test site of china on Aug. 17, 2.04 are carried out in this research. When making onboard blackbody calibration of CBERS-02.IRMSS, it is necessary to understand inside structures and light path in IRMSS camera and receive and process calibration blackbody signals at normal and high temperatures. Onboard blackbody calibration results of each detector are very important to relative radiometric calibration of images processing and absolute radiometric calibration of each detector. In-flight field calibration mainly contains field experiments, obtaining synchronous images, spectrum marching and MODTRAN radiative transmi- ssion computation. Radiometric cross-calibration of CBERS-02.IRMSS thermal band against TERRA MODIS selected 6 times synchronous images of two sensors passing through Lake Qinghai and Lake Taihu from August to December, 2.04 to compute the cross calibration data. Combining the in-flight field calibration and radiometric cross calibration data, the absolute radiometric calibration coefficients are calculated by the linear regression method. This new calibration model can obviously control the radiometric calibration uncertainties aroused by the single point method used in the in-flight calibration of CBERS-02.IRMSS, this kind of sensors cannot receive the cosmic background radiation. In this research, the radiometric calibration coefficients obtained through the linear regression model are 8.53 (gain, unit: DN/W m?2.r?1μm?1) and 44.92.(offset, unit: DN).

关键词： CBERS-02 IRMSS thermal band in-flight field calibration onboard blackbody calibration cross calibration.

Multitime scale variations of sea surface temperature in the china seas based on the HadISST dataset

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2011年第4期30卷 14-23页

作者： JIN Qihua WANG Hui Chinese Academy of Meteorological Sciences China Meteorological Administration Beijing 100081 China national Marine Environmental Forecasting center State Oceanic Administration Beijing 100081 China

The variability of the sea surface temperature（SST） in the china seas has been studied in seasonal,interannual and interdecadal scales based on the monthly data of HadISST spanning from 1870 to 2.07. The main results obtained are SST in the china offshore changes most actively at the seasonal scale with the intensity diminishing from north to south,as the temperature differences between summer and winter reaching 17 and 4 C in the northern and southern areas,respectively. Moreover,seasonal variation near the coastal regions seems relatively stronger than that far from the coastline;significant interannual variations are detected,with the largest positive anomaly occurring in 1998 in the overall area. But as far as different domains are concerned,there exists great diversity,and the difference is also found between winter and summer. Differed from the seasonal variations,where the strongest interannual variability takes place,resides to the south of that of the seasonal ones in the northern section,nevertheless in the South china Sea,the most significant interannual variability is found in the deep basin;interdecadal changes of summer,winter and annual mean SST in different domains likewise present various features. In addition,a common dominant warming in recent 2. a are found in the overall china offshore with the strongest center located in the vicinity of the Changjiang Estuary in the East china Sea,which intensifies as high as 1.3 C during the past 130 a.

关键词： china seas sea surface temperature multitime scale variations

Research progress in synthesis and catalysis of polyoxometalates

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第5期15卷 385-394页

作者： GONG Yun1, HU Changwen1* and LIANG Hong2.1. Department of Chemistry, School of Science, the Institute for Chemical Physics, beijing Institute of Technology, beijing 100081, {2. 2. Chemical Industry Press, beijing 10002., {2.) Department of Chemistry School of Science the Institute for Chemical Physics Beijing Institute of Technology Beijing 100081 China Chemical Industry Press Beijing 100029 China

Recent progress in the synthetic chemistry and catalysis of polyoxometalates (POMs) is reviewed. The novel POMs and their derivatives emerging in nearly three years (2.02.2.04) are introduced, including POMs with novel structure, POMs-organic hybrid compounds and host-guest complexes. Our review is focused on the elaboration of POMs' supramolecular chemistry.

关键词： polyoxometalates hybrid host-guest structure supramolecule catalysis.

Pulmonary embolism and deep venous thrombosis in china

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Geriatric Cardiology 2024年第8期21卷 775-778页

作者： Sheng-Shou HU the Writing Committee of the Report on Cardiovascular Health and Diseases in china Fuwai Hospital National Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina 不详

The Annual Report on Cardiovascular Health and Diseases in china(2.2.) intricate landscape of cardiovascular health in *** connection with the previous section,this eighth section of the report offers a comprehensive analysis of pulmonary embolism and deep venous *** recent years,research in the field of pulmonary vessel in china has made great progress.A number of nationwide multi-{2. registry research results have filled the gaps in the epidemiology,diagnosis and treatment of pulmonary hypertension and venous *** types of pulmonary hypertension still need attention to the identification of risk factors and/or risk stratification,and venous thromboembolism needs attention in the prevention and the overall management inside and outside *** the future,we look forward to the publication of more high-quality research in china,which could be able to improve relevant guidelines for pulmonary vascular diseases both domestically and inter-nationally.

关键词： epidemiology prevention diagnosis

Experimental study on fire smoke movement in a multi-floor and multi-room building

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2005年第3期48卷 292-304页

作者： ZHONG Maohua 1, 2., LI Peide 2., LIU Tiemin 1 , WEI Xing 1, 2.& LIAO Guangxuan 2.1. national center of Safety Science and Technology, State {2. of Work Safety, beijing 10002., china 2. State Key Laboratory of Fire Science, University of Science and Technology of china, Hefei 2.002., china 1. national center of Safety Science and Technology State Administration of Work Safety 100029 Beijing China 2. State Key Laboratory of Fire Science University of Science and Technology of China 230026 Hefei China

Fire smoke movement of multi-floor and multi-room (MFMR) fire was studied at the model test building in State Key Laboratory of Fire Science (SKLFS). The ingredient, temperature, air pressure difference and air velocity of smoke were measured and analyzed. Meanwhile, the hazard of smoke ingredient to exposed occupants was analyzed based on the national standard, Occupational Exposure Limit for Hazardous Agents in the Workplace (GBZ2.2.02.. The experimental results showed that the maximum temperature difference in MFMR fire was located along the vertical height from the fire source. With the spreading and diffusion of smoke, the temperature of smoke layer would tend to be no difference. In the fire of woodpile and kerosene, the main smoke ingredients such as SO 2., CO and CO 2.would first exceed human’s average physiological limit, while smoke ingredients such as NO and NO 2.would come behind. Because of the higher fluctuation range and frequency of air pressure difference of smoke in multi-layer building fire, the fire smoke would spread around everywhere of the passageway and made the human evacuation more difficult.

关键词： multi-floor and multi-room,fire experiment,smoke spread,smoke toxicity.

Solar release time of solar energetic particles and associated acceleration source in corona

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第2期53卷 161-168页

作者： LE GuiMing1,2.3,4, TANG YuHua1 & HAN YanBen4 1 Department of Astronomy, Nanjing University, Nanjing 2.0093, china 2.Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, china Meteorological {2., beijing 100081, china 3 national center for Space Weather, china Meteorological {2., beijing 100081, china 4 national Astronomical Observatories, Chinese Academy of Sciences, {12. 100012. china Department of Astronomy Nanjing University Nanjing China Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites China Meteorological Administration Beijing China national center for Space Weather China Meteorological Administration Beijing China national Astronomical Observatories Chinese Academy of Sciences Beijing China

Solar energetic particles (SEPs) are accelerated in corona at an early phase of solar energetic particle events (SEPE). The acceleration mechanism of SEPs in corona can only be inferred from an analysis of multi-band observational data, as the observation of SEPs is usually made around 1AU. In this context, people have investigated spectrums, charge state, solar release time (SRT), and multi-band data of SEPEs, in an attempt to judge the acceleration mechanism of SEPs. The SRT computation of SEPs is an important and commonly used approach to study the acceleration mechanism of SEPs in corona. This paper reviews some important findings concerning the SRT computation of SEPs, and analyzes different merits of each approach for such calculation, based on a range of SEPE case studies. This paper also analyzes and discusses both possible and actual acceleration mechanisms of a number of SEPEs, by calculating the SRT of the SEPEs. Finally, the paper summarizes the possible problems in studying an acceleration mechanism of SEPEs inferred from the SRT of SEP.

关键词：阳光释放时间加速度电晕太阳耀斑