Monitoring dynamic changes of global land cover types:fluctuations of major lakes in China every 8 days during 2000–2010

Remote sensing images can be used to delineate variations in the area of lakes and to assess the influence of environmental changes and human activities.However,because lakes are dynamic,results obtained from individual images acquired on a single date are not representative and do not accurately reflect ongoing changes.In this study,we used 8-day moderate resolution imaging spectroradiometer(MODIS)composite data from 2000 to2010 to map water surface changes over 629 lakes in China.We combined automatic extraction of training data and support vector machine classification to derive the spatial distribution of these large water bodies.The producer’s and user’s accuracies for MODIS images were91.06%and 89.81%,respectively,when compared with interpretation results from 30 m resolution Landsat images taken on similar days.Area changes,variability,inundation intensity,and rainy seasons of the 629 lakes were analyzed based on this multi-temporal lake database.The total area of the 629 lakes increased over the study period,primarily as a result of the expansion of lake areas on the Tibetan Plateau.There were 12 lakes with a maximum area[1,000 km2,and six of these decreased in area from 2000to 2010.The shrinkages of Poyang Lake and Dongting Lake were-54.76 and-25.08 km2/a,respectively.The area of lakes on Tibetan Plateau,in northern Xinjiang,northeastern Inner Mongolia,and northeastern China varied little,while lakes on the Yangtze Plain,in southern Inner Mongolia,and central Xinjiang fluctuated considerably.Inundation intensity increased for lakes on the Tibetan Plateau,in northern Xinjiang,Heilongjiang,and Jilin,while inundation extent decreased in central Xinjiang,southern Tibet,southern Inner Mongolia,Sichuan,and on the Yangtze Plain.This study is an attempt to develop high-frequency specific land cover maps to improve applicability of general land cover maps.The lake products serve as an important supplement to hydrologic data.The lake database enables the generation of new land surface process models,which could improve the precision of simulations,based on more accurate observations of dynamic lake systems.     

Laser intensity induced transparency in atom-molecular transition process

We propose a new transparency mechanism, which is based on photoassociation （PA） laser intensity induced transitional frequency shift for ultracold cesium molecules formed in PA scheme. The PA laser intensity is supposed to change before the atommolecule resonance. Thus, a remarkable transparent effect for PA laser is expected to appear in the vicinity of original resonant transitional line, where the variation of PA laser intensity induces the shift of the excited molecular levels. The mechanism is different from electromagnetically induced transparency effect and interesting for further research on the scattering length for cesium atomic condensate.     

Effects of climate change on biodiversity

1 Rise of studies on climate change＇s effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America＇s annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].     

Joining of Si3N4 ceramic using PdCo(Ni SiB)–V system brazingfi ller alloy and interfacial reactions

The wettability of V-active PdCo-based alloys on Si3N4ceramic was studied with the sessile drop method. And the alloy of Pd50.0–Co33.7–Ni4.0–Si2.0–B0.7–V9.6(wt%),was developed for Si3N4ceramic joining in the present investigation. The rapidly-solidified brazing foils were fabricated by the alloy Pd50.0–Co33.7–Ni4.0–Si2.0–B0.7–V9.6. The average room-temperature three-point bend strength of the Si3N4/Si3N4joints brazed at 1453 K for 10 min was 205.6 MPa,and the newly developed braze gives joint strengths of 210.9 MPa,206.6 MPa and 80.2 MPa at high temperatures of 973 K,1073 K and 1173 K respectively. The interfacial reaction products in the Si3N4/Si3N4joint brazed at 1453 K for10 min were identified to be VN and Pd2Si by XRD analysis. Based on the XEDS analysis result,the residual brazing alloy existing at the central part of the joint was verified as Co-rich phases,in which the concentration of element Pd was high up to 18.0–19.1 at%. The mechanism of the interfacial reactions was discussed. Pd should be a good choice as useful alloying element in newer high-temperature braze candidates for the joining of Si-based ceramics.     

Ga(Ⅲ)在罗丹明B和丙醇的水溶液中与Zn(Ⅱ)、Al(Ⅲ)、Ir(Ⅳ)、Rh(Ⅲ)、V(Ⅴ)和Ti(Ⅳ)的绿色萃取分离

丙醇水溶液在氯化钠的作用下可分成醇-水两相,在分相过程中,GaCl4-与罗丹明B(RhB)生成的[GaCl4-][RhB+]能被丙醇相完全萃取.当溶液中丙醇和罗丹明B的浓度分别为30%(v/v),0.3 g/L时,Ga(Ⅲ)的萃取率达到97.8%以上,而Zn(Ⅱ)、Al(Ⅲ)、Ir(Ⅳ)、Rh(Ⅲ)、V(Ⅴ)和Ti(Ⅳ)基本不被萃取,实现了Ga(Ⅲ)与上述金属离子的分离.     

支持海量数据的分布式数据库架构设计与验证

结合电信行业实际业务需求,利用数据库代理,设计出了能够提供强一致性、高可用性并支持弹性水平扩展能力的分布式数据库架构.验证结果表明,对于分布式数据库采用数据库代理可满足高可用性与弹性水平扩展的设计要求,实际部署中,双Master部署模式性能体现较佳,读写分离的部署模式、读写操作部署在一台设备性能下降明显,说明数据库代理可以实现高可用性的分布式数据库架构,各类部署架构中影响性能的是磁盘I/O.     

基于DEA的环渤海能源利用效率研究

环渤海经济圈的迅速崛起,对国家经济发展发挥着巨大的推动作用.从能源视角,采用数据包络分析法对环渤海地区、长三角地区的上海市和浙江省、珠三角地区的广东省2000—2011年能源利用效率进行了测度.结果显示,环渤海地区的能源利用效率要低于长三角地区和珠三角地区.目前,环渤海地区四省两市一区的能源利用效率排名依次为:北京、天津、辽宁、内蒙古、山东、河北、山西.在此基础上提出了提高环渤海能源利用效率的对策.     

基于ARCGIS的河南省分区农业旱灾风险分析

针对以往研究中旱灾发生概率计算精度不高、权重确定不够客观等不足,利用信息扩散理论和农业旱灾风险指数法,从致灾因子、孕灾环境、承灾体和抗旱减灾能力4个方面选取相应的评估指标,基于ARCGIS平台,对河南省农业旱灾风险进行分区分析.结果表明:濮阳和安阳处于致灾因子高危险区;鹤壁和新乡处于孕灾环境高敏感区;焦作和济源处于承灾体高脆弱区;开封、郑州、洛阳处于高抗旱减灾能力区.综合各影响因素的风险指数,安阳、鹤壁和济源处于农业旱灾高风险区.     

基于模糊物元法的我国六大城市旅游供给评价研究

目的地城市旅游供给评价是旅游研究的重要内容.以入境旅游为视角,基于市场调研数据,构建了目的地城市旅游供给指标评价体系,借鉴模糊物元模型对我国六大城市的旅游供给水平进行测评,把目的地城市旅游供给要素分为核心、辅助和瓶颈等3个要素层次.结果发现:北京、上海、西安和成都为二级供给水平,广州和昆明为三级供给水平;形成了目的地城市供给评价的3883结构;城市间旅游供给要素水平存在差异,供给特色鲜明;模糊物元模型在旅游供给水平测评上具有较好的操作性和科学性.     

基于TM/ETM+遥感影像的达里湖补给源研究

以近十年的多时相Land Sat TM/ETM+影像为数据源,从面积、变化率等方面对湖泊的变化过程进行研究,并结合达里湖流域临近四个雨量站的降雨量、蒸发量数据进行分析.结果表明,达里湖从2003—2013年湖面面积不断减小,面积由204.11 km2减小到180.02 km2,面积减少了24.09 km2,平均每年减少2.41 km2;近十年来,达里湖流域降雨量波动较大,但是没有明显减少趋势,流域蒸发量波动较小且远大于当地降雨量.分析达里湖流域湖泊面积变化与降雨量和蒸发量的关系显示,降雨量并非湖泊面积变化的决定性因素,蒸发量对湖泊面积变化影响较小.达里湖除接受降水补给外,还接受地下水的补给,且地下水可能并非来自当地降水.