用基于相对辐射校正的TM影像监测绍兴土地覆盖变化

基于绍兴市1984年和1997年的两期TM影像，用相对辐射校正方法将1997年的影像校正到1984年的辐射水平上，消除多时相遥感影像问地物的辐射差异，对两期影像分别做最大似然分类，构建覆盖转移矩阵，将分类图分析运算构建覆盖变化分类混淆矩阵，并结合土地覆盖变化的驱动因子，分析得出，绍兴土地覆盖变化主要因素是城镇的扩展及人们饮食结构的变化。     

中间包包盖长寿综合技术的研究与应用

通过对武钢第一炼钢厂中间包包盖实际使用状况与破损形式的现场调研，分析了引起包盖破损的主要原因，制定了延长包盖使用寿命与改善包盖使用性能的综合技术措施，完成了高抗热震性莫来石-刚玉质浇注料的研究、长寿命中间包包盖的结构设计与工业性试验，取得了包盖寿命28个浇次的试验效果，强化了包盖的隔热防护作用，     

Wave-generated fractures in river ice covers

The breakup of the ice cover in northern rivers is a brief but crucial event in the life cycle of many aquatic species and can trigger extreme ice jam events with major socio-economic impacts and significant climate change implications. An important, but vaguely understood, breakup process is the fracture of the winter ice cover by low-amplitude water waves. Previous work on this subject has been based on the assumption of an infinitely long wave propagating under an infinitely long and “edgeless” ice cover. This configuration does not account for structural constraints imposed by the proximity of an ice edge or a transverse crack. Consequently, it only furnishes approximate values of bending stresses, and tells little about the spacing of cracks that may be generated by an advancing wave, which is the only visual evidence that can identify the relevant fracture mechanism in the field. Herein, edge proximity is taken into account by making plausible simplifications to the ice response equation, and using wave forms of limited extent. It is shown that such conditions generally produce higher bending stresses than does the infinite wave/edgeless cover configuration. The distance of the peak bending stress from the edge, which defines the spacing of cracks, varies with wavelength and is less than 100 ice thicknesses or so. This is comparable to that of high-amplitude, single waves (or surges) that result from ice jam releases, but much less than fractures generated by bending on horizontal planes, caused by the meandering river plan form. Comparison of the present results with the limited available evidence indicates that wave-generated fractures occur during the passage of ice jam release surges.     

冲压工艺技术在电机端盖制造中的应用

分析了压缩机用电机端盖的结构工艺,介绍了电机端盖冲裁和拉深工艺的具体设计;充分利用拉深、反拉深交替进行的方法,抵消拉深产生的残余应力;提高拉深成形的可靠性,确保产品质量.     

A land cover classification product over France at 1 km resolution using SPOT4/VEGETATION data

The present study focuses on the development of a new land cover classification product over France at 1 km resolution. It is based on data sets from the Earth observing system SPOT4/VEGETATION. The satellite measurements are aimed at supporting regional efforts to set up global mosaics on new land cover products. They have been acquired in the frame of the Global Land Cover 2000 project. The instrument design relies on advanced technology, which leads to an improved radiometric and geometric resolution data. Such characteristics allow taking full benefit of the daily repetitiveness of the VEGETATION wide field-of-view sensor without the drawback of a variable pixel size on the image edge. Several physical processing steps are successively operated to the images on a per-pixel basis to remove detector blindness, to filter cloud contamination, and finally to correct both atmospheric and surface anisotropy effects. A new thematic map using the K-means clustering method has been built. First, the results of the satellite-based land cover classification has been successfully compared with the Coordination of Information on the Environment (CORINE) database which serves as a reference to appraise the reliability of the study. Then, it has been inter-compared with land cover products derived from MODIS and AVHRR sensors. For this, an aggregative scheme particularly focused on major land units (forest, grassland, cropland) adopted in order to yield a whole mapping at the same geographic projection and space resolution. The discrepancies between maps enhance the quality of the proposed product, thanks to the use of advanced data processing and a more appropriate method.     

Remote sensing of vegetation and land-cover change in Arctic Tundra Ecosystems

The objective of this paper is to review research conducted over the past decade on the application of multi-temporal remote sensing for monitoring changes of Arctic tundra lands. Emphasis is placed on results from the National Science Foundation Land-Air-Ice Interactions (LAII) program and on optical remote sensing techniques. Case studies demonstrate that ground-level sensors on stationary or moving track platforms and wide-swath imaging sensors on polar orbiting satellites are particularly useful for capturing optical remote sensing data at sufficient frequency to study tundra vegetation dynamics and changes for the cloud prone Arctic. Less frequent imaging with high spatial resolution instruments on aircraft and lower orbiting satellites enable more detailed analyses of land cover change and calibration/validation of coarser resolution observations.The strongest signals of ecosystem change detected thus far appear to correspond to expansion of tundra shrubs and changes in the amount and extent of thaw lakes and ponds. Changes in shrub cover and extent have been documented by modern repeat imaging that matches archived historical aerial photography. NOAA Advanced Very High Resolution Radiometer (AVHRR) time series provide a 20-year record for determining changes in greenness that relates to photosynthetic activity, net primary production, and growing season length. The strong contrast between land materials and surface waters enables changes in lake and pond extent to be readily measured and monitored.     

变速箱上盖拔叉孔加工夹具设计

变速箱上盖是汽车用来换档的重要零部件之一,它可以改变传动比,满足不同行驶条件对牵引力的需要。就变速箱上盖拔叉孔加工夹具设计方案进行论述,通过采用这套夹具体和钻模,不但保证了工件的形位要求,提高了该产品的加工质量,同时也缩短了辅助加工时间,提高了生产效率。     

MDS800-60双吸泵的研制与开发

根据辽源泵业公司现有泵型及技术力量在MD580-60泵的基础上对吸水段和首级叶轮进行设计改造,开发出一种新产品MD580-60双吸泵,以扩大市场竞争力。     

230t钢包高效保温技术的研究与应用

济钢宽厚板厂210 t转炉钢包加覆盖剂保温存在保温效果差、钢水降温大、能耗高、污染环境等问题,通过实施钢包加盖保温技术,有效提高了钢衬温度,降低转炉出钢温度损失,大幅度降低能耗,合计吨钢降成本9.63元,年创经济效益千万元以上。     

Evaluation of a cloud cover based model for estimation of hourly global solar radiation in Western Canada

Cloud cover based solar radiation models are relatively simple and convenient as the models require the input of cloud cover data which are mostly available from the meteorological stations. In this study, the performance of a cloud cover based solar radiation model (Kasten–Czeplak model) with original or locally fitted coefficients was evaluated for estimating the hourly global solar radiation for four different locations in Western Canada. The average value of R², mean bias error, and root mean square error are 0.69, ?61.6, and 157.9?W?m^?2, respectively, for the model with original coefficients, whereas 0.82, 4.4, 107.1?W?m^?2 with locally fitted coefficients. Results show that the Kasten–Czeplak model with locally fitted coefficients satisfactorily estimated the hourly solar radiation of four different locations in Western Canada. Also, the results indicate that the model with original coefficients has very limited accuracy under intermediate cloud cover conditions.