新版GB/T19056电磁环境适应性要求分析

介绍了GB/T 19056新版本对汽车行驶记录仪电磁环境适应性要求,比较和分析了新旧版本在电磁环境适应性方面的的异同,重点介绍了新版标准中瞬态抗扰性脉冲的波形和参数要求,研究和探讨了标准中对产品电磁环境适应性要求的内涵.     

空间数据挖掘的应用技术

空间数据挖掘技术是数据挖掘技术与空间数据库技术的融合,在GIS遥感、图像数据库、医疗影像处理等领域具有广阔的应用前景。基于空间数据挖掘的特点,论述了其在GIS中的应用,指出了空间数据挖掘面临的问题,并阐述了空间数据挖掘的发展趋势。     

上海市烟气排放连续监测系统的数据审核机制

随着烟气排放连续监测系统(CEMS)的广泛安装和验收,CEMS数据的应用将成为污染源管理最直接最有效的手段.在国家规定的数据有效性审核基础上,结合实际工作遇到的问题和长期实践经验,提出每日审核对于数据有效性的重要作用,并通过上海市特有的CEMS数据审核机制,介绍该审核机制的建立背景、内容、流程及取得的成果.     

基于DEA方法的上海农业水灾脆弱性评估

采取演绎思路,在历史灾情的基础上,根据脆弱性概念,运用包络分析的CCR投入-产出模型,对上海各郊区(县)的农业水灾脆弱性分异规律进行了分析。结果表明:松江与南汇脆弱性达1的年数最多,宝山、金山与青浦处于中等,嘉定、浦东、奉贤与崇明脆弱性达1的年数最少;另外1,991年为水灾形势最为严峻的年份,其次是1985年,1987-1990年间,各区(县)的脆弱性值都偏小,没有脆弱性达1的区域。这与实际情况基本符合,该方法可以为市政部门提供必要信息和决策参考,以提高灾害科学管理的水平。     

2009年秋至2010年春我国西南地区干旱及与历史场次干旱对比分析

2009年10月至2010年4月,我国西南地区由于受厄尔尼诺影响,气温偏高、降雨偏少,发生了秋冬春三季连旱,耕地受旱面积占全国同期耕地受旱面积的78%,受灾人口和大牲畜饮水困难头数都达到了近十年来该地区的最高水平.通过对比本次和历史场次干旱发现,西南干旱并非稀遇现象,195l～1990年的40年间该地区曾发生干旱12次...     

Predicting Bird Species Distributions in Reconstructed Landscapes

Abstract:  Landscape optimization for biodiversity requires prediction of species distributions under alternative revegetation scenarios. We used Bayesian model averaging with logistic regression to predict probabilities of occurrence for 61 species of birds within highly fragmented box–ironbark forests of central Victoria, Australia. We used topographic, edaphic, and climatic variables as predictors so that the models could be applied to areas where vegetation has been cleared but may be replanted. Models were evaluated with newly acquired, independent data collected in large blocks of remnant native vegetation. Successful predictions were obtained for 18 of 45 woodland species (40%). Model averaging produced more accurate predictions than "single best" models. Models were most successful for smaller-bodied species that probably depend on particular vegetation types. Predictions for larger, generalist species, and seasonal migrants were less successful, partly because of changes in species distributions between model building (1995–1997) and validation (2004–2005) surveys. We used validated models to project occurrence probabilities for individual species across a 12,000-km² region, assuming native vegetation was present. These predictions are intended to be used as inputs, along with landscape context and temporal dynamics, into optimization algorithms to prioritize revegetation. Longer-term data sets to accommodate temporal dynamics are needed to improve the predictive accuracy of models.     

铁路轨道状态分析信息系统设计与实现

研究了轨道状态分析信息系统的设计与实现方法。利用检测数据作为分析轨道状态的出发点,研究轨道状态的变化趋势,在分析国内现有铁路工务管理系统中存在的数据资源分散、忽视历史数据积累等问题的基础上,阐述了构建铁路轨道状态分析信息系统的可行性和必要性,并采用数据仓库技术和地理信息系统(GIS)技术,从空间和时间两个维度分析数据,提出了建立轨道状态预测模型的趋势分析法。笔者研究的核心内容是如何在整合各类轨道动、静态检测数据及铁路运营数据的基础上,建立轨道状态预测模型,为掌握及预测轨道状态变化趋势提供可靠的分析工具。     

Study on Dynamic Mechanism of Urban Expansion： A Case Study of Shandong Province

This paper aims at studying the dynamic mechanism of urban expansion and its role. Based on the economic model of urban spatial structure and applying panel data in Shandong Province, the paper concludes. Economic growth and transition of economic structure have played the most powerful role in urban expansion. An increase in population helps the core to extend. Increasing agricultural productivity can provide a countervailing force. An increase in transportation costs will limit urban expansion. An increase in the marginal productivity of land in housing production will increase urban expansion. Fiscal and taxation policies also have encouraged the extensive shift of cultivated land into build-up area. This paper also suggests that if high rate increasing GDP is needed, the urban core will continue to expand. The government should take measures to improve the rapid growth of the city.     

A Chronology of Nitrogen Deposition in the UK Between 1900 and 2000

Measurements of the concentrations of nitrogen compounds in air and precipitation in the UK have been made since the mid-19th century, but no networks operating to common protocols and having traceable analytical procedures were established until the 1950s. From 1986 onwards, a high-quality network of sampling stations for precipitation chemistry was established across the UK. In the following decade, monitoring networks provided measurement of NO₂, NH₃, HNO₃ and a satisfactory understanding of the dry deposition process for these gases allowed dry deposition to be quantified. Maps of N deposition for oxidized and reduced compounds at a spatial scale of 5 km × 5 km are available from 1986 to 2000. Between 1950 and 1985, the more limited measurements, beginning with those of the European Air Chemistry Network (EACN) provide a reasonable basis to estimate wet deposition of NO ₃ ^– –N and NH ₄ ⁺ –N. For the first half of the century, estimates of deposition were scaled with emissions assuming a constant relationship between emission and deposition for each of the components of the wet and dry deposition budget at the country scale. Emissions of oxidized N, which dominated total nitrogen emissions throughout the century, increased from 312 kt N annually in 1900 to a peak of 787 kt for the decade 1980–1990 and then declined to 460 kt in 2000. Emissions of reduced N, largely from coal combustion were about 168 kt N in 1900, increasing to a peak of 263 kt N in 2000 and by now dominated by agricultural sources. Reduced N dominated the deposition budget at the country scale, increasing from 163 kt N in 1900 to 211 kt N in 2000, while deposition of oxidized N was 66 kt N in 1900 and 191 kt N in 2000. Over the century, 68 Mt (Tg) of fixed N was emitted within the UK, 78% as NO _x , while 29 Mt of nitrogen was deposited (43% of emissions), equivalent to 1.2 t N ha^–1, on average, with 60% in the reduced form. Deposition to semi-natural ecosystems is approximately 15 Tg N, equivalent to between 1 and 5 t N ha^–1, over the century and appears to be accumulating in soil. The N deposition over the century is similar in magnitude to the total soil N inventory in surface horizons.     

基于多源辅助数据和神经网络模型的稻田土壤砷空间分布预测

合适的方法和多源的辅助数据对于准确预测土壤重金属的空间分布具有重要意义.该研究提出一种径向基函数神经网络结合普通克里格法的模型(RBFNN_OK),由主成分分析(PCA)提取的地形因子、遥感数据和邻近信息等多源辅助数据作为自变量,预测江西省都昌县稻田土壤砷空间分布.为验证RBFNN_OK的可行性:首先在全县范围内采集144个稻田表层(0～20 cm)土壤样品,运用ArcGIS地统计模块随机抽取115个(80%)采样点作为测试集,29个(20%)采样点作为验证集.其次多源辅助数据包括地形因子、遥感数据和邻近信息等14个定量因子作为预测变量,将预测变量进行主成分分析,得到前10个主成分的累积贡献率达到97.62%.再次一个特定的RBFNN_OK被用来预测土壤砷空间分布.最后将RBFNN_OK模型的预测结果与径向基神经网络模型(RBFNN)、回归克里格模型(RK)和多元逐步线性回归模型(MSLR)进行比较.结果表明,RBFNN_OK的测量值标准偏差与均方根误差的比值(RPD)较其它3种方法分别提高了14.92%、35.71%和44.67%.此外,RBFNN_OK还提供了更加真实且有关土壤砷空间分布的细节信息.RBFNN_OK取得最优效果可能归因于引入多源辅助数据,考虑多源辅助数据和土壤砷之间的多重共线性和非线性关系.该方法可为稻田土壤砷调查与环境保护提供更为精准的信息.