基于NDVI密度分割的冬小麦种植面积提取

为解决作物面积遥感监测中常遇的混合像元问题,选用江苏省沭阳县冬小麦扬花期HJ-1A卫星遥感影像,基于不同地物光谱信息的差异性与可分割性,提出基于归一化植被指数(NDVI)密度分割的冬小麦种植面积提取方法。在利用GPS实地取样调查和建立解译标志的基础上,对HJ-1A卫星影像进行了几何与大气校正。利用NDVI灰度影像提取混合像元训练样本的NDVI值和小麦种植面积,计算小麦面积权重,确定混合像元的NDVI阈值。利用NDVI再归一化结果对NDVI灰度影像进行密度分割,依据不同密度分割系数下像元总面积及其所对应的小麦面积权重关系,最终得到沭阳县冬小麦种植面积。结果表明,根据NDVI密度分割法提取冬小麦面积为8.37×104 hm2,面积精度为92.37%,样本精度为93.31%。基于密度分割系数(P0.5)制作沭阳县冬小麦种植分布图,获取了全县冬小麦空间分布特征信息。以上结果说明NDVI密度分割法能较准确地提取研究区内冬小麦种植面积,可有效解决农作物种植面积提取中混合像元问题。     

Index of soil aggregates stability as linear function value of transition matrix elements

The paper presents a new index which is an innovative tool for the analysis of soil aggregates stability. The soil aggregates stability index (ASI) is based on a linear function value of transition matrix elements with coefficients being properly chosen weights. Each element of the transition matrix is a frequency (empirical probability) of aggregates transition from one class of size to another or within the same class. The proposed weights give an ASI value range from 1 to 32 and are thus formulated: a higher ASI value corresponds to a higher aggregates stability. The usefulness of the proposed index is illustrated in the case three soils (Haplic Phaeozem, Mollic Gleysol and Orthic Rendzina) for which aggregate water stability was determined by three different methods.     

应用证据权法预测南美斑潜蝇的发生

利用证据权法,选择温度、湿度、降水量及日照时数作为影响南美斑潜蝇数量的证据层,通过计算后获得其相应的先验概率（P先验）、权重（W）及相关系数（C）等,并根据后验概率（P后验）的计算结果对各预测点进行验证,可知有80%的发生点分布在中、高概率区,说明该预测模型对农业虫害防治工作具有一定的指导作用。     

中草药饲料添加剂对大鼠泌乳及乳腺发育的影响

在基础催乳方中分别添加含有异黄酮雌激素的两种中草药葛根和黄芪,测定其对大鼠泌乳、仔鼠增重和乳腺发育的影响。结果表明:葛根 基础方和黄芪 基础方组的仔鼠增重显著高于对照组和基础方组(P<0.05),而葛根和黄芪组仔鼠增重差异不显著(P>0.05),且对照组和基础方组差异也不显著(P>0.05)。剥离泌乳大鼠腹部一侧乳腺,测定大鼠乳腺组织中DNA和RNA的含量,结果表明葛根组和黄芪组的DNA、RNA和RNA/DNA明显高于对照组,与基础方组差异不显著(P<0.05);葛根组和黄芪组的RNA/DNA显著高于对照组,而与基础方组差异不显著。     

农村中心居民点选址方法探讨

利用GIS空间分析技术分析农村居民点现状布局,选取农村居民点规模、道路、耕地、中心集镇、河流分布作为影响中心居民点选址的重要因素,并确定各因素权重,运用缓冲区分析对居民点各影响因素进行量化,最后以多指标综合评分叠加法得到居民点的综合分值,再根据现状确定中心居民点的数量及位置。     

城镇土地定级权值量化研究

运用回归模型法对土地定级因素权重值进行研究,具体分析并比较了传统特尔斐法赋权与回归模型赋权的方法和步骤,通过对江苏省常州市武进区全区土地定级权值量化研究的实例分析,得出客观赋权法的客观合理性和可行性,使权重赋值更加符合实际。     

Mapping the probability of large fire occurrence in northern Arizona, USA

In the southwestern U.S., wildland fire frequency and area burned have steadily increased in recent decades, a pattern attributable to multiple ignition sources. To examine contributing landscape factors and patterns related to the occurrence of large (⩾20 ha in extent) fires in the forested region of northern Arizona, we assembled a database of lightning- and human-caused fires for the period 1 April to 30 September, 1986–2000. At the landscape scale, we used a weights-of-evidence approach to model and map the probability of occurrence based on all fire types (n = 203), and lightning-caused fires alone (n = 136). In total, large fires burned 101,571 ha on our study area. Fires due to lightning were more frequent and extensive than those caused by humans, although human-caused fires burned large areas during the period of our analysis. For all fires, probability of occurrence was greatest in areas of high topographic roughness and lower road density. Ponderosa pine (Pinus ponderosa)-dominated forest vegetation and mean annual precipitation were less important predictors. Our modeling results indicate that seasonal large fire events are a consequence of non-random patterns of occurrence, and that patterns generated by these events may affect the regional fire regime more extensively than previously thought. Identifying the factors that influence large fires will improve our ability to target resource protection efforts and manage fire risk at the landscape scale.     

汉唐粮食亩产反映的度量衡问题

汉代、唐代乃至以后的宋元明清各代,亩产均记为当时的一石,这是个有趣的现象。粮食亩产量、度量衡制、亩制在不断变化,这就要求三者的变化要一定的规范,在变化中是相互关照的。“石”本为重量单位,但在亩产量上也为容量单位,度量衡在设定时就已照顾到三者之间的对应关系。历代存在着以黍粒检校度量衡的制度,这种制度又必然与黍粒的变化存在着一定的联系。     

GIS analysis of spatial patterns of human-caused wildfire ignition risk in the SW of Madrid (Central Spain)

The majority of wildfires in Spain are caused by human activities. However, much wildfire research has focused on the biological and physical aspects of wildfire, with comparatively less attention given to the importance of socio-economic factors. With recent changes in human activity and settlement patterns in many parts of Spain, potentially contributing to the increases in wildfire occurrence recently observed, the need to consider human activity in models of wildfire risk for this region are apparent. Here we use a method from Bayesian statistics, the weights of evidence (WofE) model, to examine the causal factors of wildfires in the south west of the Madrid region for two differently defined wildfire seasons. We also produce predictive maps of wildfire risk. Our results show that spatial patterns of wildfire ignition are strongly associated with human access to the natural landscape, with proximity to urban areas and roads found to be the most important causal factors We suggest these characteristics and recent socio-economic trends in Spain may be producing landscapes and wildfire ignition risk characteristics that are increasingly similar to Mediterranean regions with historically stronger economies, such as California, where the urban-wildland interface is large and recreation in forested areas is high. We also find that the WofE model is useful for estimating future wildfire risk. We suggest the methods presented here will be useful to optimize time, human resources and fire management funds in areas where urbanization is increasing the urban-forest interface and where human activity is an important cause of wildfire ignition.     

高致病性禽流感传播的风险评估框架的建立

为实现对高致病性禽流感传播的风险评估，以在该病的控制中制定科学有效的控制策略，本研究在分析高致病性禽流感传播风险因素的基础上，汲取各类风险分析的原则，确定了高致病性禽流感传播风险评估指标，并采用层次分析法(AHP)确定各风险因素的权重，结合多指标综合评价函数，建立了包括评估指标体系、指标评价标准、指标权重、综合评分和数据采集五个方面的高致病性禽流感传播风险评估框架。