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231.
Abstract

In this study, the wind energy potential of Elazig is statistically analyzed based on hourly measured wind speed data over the five-year period from 1998 to 2002. The probability density distributions are derived from cumulative distribution functions. Two probability density functions are fitted to the measured probability distribution on a yearly basis. The wind energy potential of the location is studied based on the Weibull and Rayleigh distributions. It was found that the numerical values of both Weibull parameters (k and c) for Elazig vary over a wide range. The yearly values of k range from 1.653 to 1.878 with an average value of 1.819, while those of c are in the range of 2.757–2.994 m/s with an average value of 2.824 m/s. In addition, yearly mean wind speed and mean power density of Elazig is found as 2.79 m/s and 38.76 W/m2, respectively. The wind speed distributions are represented by Weibull distribution and also by Rayleigh distribution, with a special case of the Weibull distribution for k = 2. As a result, the Rayleigh distribution is found to be suitable to represent the actual probability of wind speed data for Elazig.  相似文献   
232.
为挖掘飞行数据中的高危险性操作模式,采用k-SC时间序列聚类算法,并基于K-W检验分析聚类结果与不安全事件之间的关系。以特定条件下某机队着陆阶段的驾驶杆操作数据和长着陆事件为例进行模型验证。结果表明:机队有5类不同的驾驶杆操作模式;不同操作模式的着陆平飘距离分布具有显著性差异,且长着陆的危险性最高可达68.18%。研究结果可为提升航空公司飞行员操作能力、分析飞行员操作特性及其他不安全事件(如重着陆、擦机尾等)提供理论参考。  相似文献   
233.
基于实测光谱分析和MODIS数据鄱阳湖叶绿素a浓度估算   总被引:1,自引:0,他引:1  
基于遥感的大面积水体监测技术为水环境监测提供了一种有效手段。以鄱阳湖为研究区,以反映水体营养状态的重要指标叶绿素a为研究对象,在测定研究区水体光谱及叶绿素a浓度和收集了相应时间的MODIS数据的基础上,采用浮游藻类指数法(Floating Algae Index,FAI)提取鄱阳湖水体范围,对鄱阳湖水体实测光谱数据进行剔除异常、归一化及光谱微分处理,构建波段差值、比值、归一化差值等光谱指数,利用最小二乘原理迭代分析水体叶绿素光谱响应特征,得出敏感波段范围:673~680 nm与650~665 nm、680~710 nm与650~670 nm、662~671 nm与700~720 nm光谱区间组合。选择最佳通道组合,建立基于MODIS影像的鄱阳湖叶绿素a浓度反演模型,相关系数为067。应用该模型得到2011年秋季鄱阳湖的叶绿素浓度估算值,反演结果显示湖区水体叶绿素浓度总体不高,且在空间分布上湖区水体周边与陆地交界处比湖中心区浓度偏高。分析认为:通过对实测光谱的定量分析,获得对鄱阳湖地区水体叶绿素浓度的光谱特征认识,揭示出其反射光谱的长波漂移现象,为鄱阳湖这一富营养化程度底,且水体分布不均匀区域建立一种叶绿素浓度反演方法,可为该区域长期的水环境管理提供方法借鉴  相似文献   
234.
Using historical General Land Office record as a reference, this study employed a landscape-scale disturbance and succession model to estimate the future cumulative effects of six alternative management plans on the tree species composition for various physiographic settings for the Mark Twain National Forest in Missouri. The results indicate that over a 200-year horizon, the relative abundance of black oak and pine species groups will decrease and the relative abundance of the white oak species group will increase, regardless of management strategy. General Land Office witness tree records provide a measure of tree species composition in the period from 1800 to 1850, prior to the large-scale influx of European settlers. Compared to the tree species composition described in the General Land Office records, the six contemporary management alternatives considered all would lead to a lower abundance of pine species, a higher abundance of red/black oak species, and a slightly higher abundance of white oak species after 200 years. Impacts of management on tree species composition varied with physiographic settings. The projected relative abundance of pine differed significantly across the five physiographic classes over the first 40 years of the simulation. In the medium term (simulation years 41-100) the projected relative pine abundance differed significantly among only four physiographic classes. In the long term (simulation years 100-200) the projected relative pine abundance differed for only one physiographic class. In contrast, differences among physiographic classes in the relative abundance of black oaks and white oaks increased over time. In general, the expected long-term differences in relative tree species abundance among six proposed alternative management plans are small compared to shifts in tree species composition that have occurred from 1850 to the present.  相似文献   
235.
中国工业废水治理效率评价   总被引:1,自引:0,他引:1  
基于投入产出的思想,应用DEA模型对2008年中国工业废水治理效率进行静态评价,得出各地区当前工业废水治理效率.用Malmquist指数对中国2003-2008年工业废水治理效率进行动态评价,分别得出近几年中国工业废水治理的名义全要素生产率和实际全要素生产率.结果表明,中国工业废水平均治理效率仅为0.630,2008年达到DEA有效的地区仅占16.7%,几乎所有地区都处在规模收益递减;2003-2008年间的中国工业废水治理名义T下P为0.922,实际TFP为0.943,即分别在此期间平均每年下降7.8%和5.7%,造成逐年下降的主要原因是技术的落后.  相似文献   
236.
云南高原湖泊流域土地利用与水质变化异质性分析   总被引:1,自引:0,他引:1  
以云南省九大高原湖泊为例,通过面板数据方式分析对高原湖泊流域土地利用类型变化,通过库兹涅兹曲线相关内容对利用强度的分析以及与水质的动态变化情况,得到耕地、园地、湿地面积与湖泊含磷量存在一定负相关.林地、牧草地、建设用地面积与湖泊含磷量存在一定正相关.牧草地、耕地、园地、湿地面积与湖泊含氮量存在一定负相关,建设用地面积与湖泊含氮量存在一定正相关.园地和耕地面积与污染综合指数存在负相关,建设用地面积与污染综合指数存在负相关.分析指出,滇池、泸沽湖处于流域协调区间,阳宗海、抚仙湖、星云湖、程海处于流域冲突区间,洱海、异龙湖处于冲突区间向协调区间转型过程中.  相似文献   
237.
The Clean Development Mechanism (CDM) allows industrialized countries to comply with the Kyoto Protocol by using carbon offsets from developing countries. There are two puzzles within this carbon market: additionality (the proposed activity would not have occurred in its absence) and co-benefits (the project has other environmental benefits besides climate mitigation). This paper proposes an econometric approach to evaluate the CDM effect on sulfur dioxide emission reductions and assess its additionality indirectly. Our empirical model is applied to China's emissions at the prefecture level. We found that the CDM does not have a statistically significant effect in lowering sulfur dioxide emissions. This result casts doubt on additionality of these CDM activities, that is, they would have happened anyway.  相似文献   
238.
Estimating influence of stocking regimes on livestock grazing distributions   总被引:1,自引:0,他引:1  
Livestock often concentrate grazing in particular regions of landscapes while partly or wholly avoiding other regions. Dispersing livestock from the heavily grazed regions is a central challenge in grazing land management. Position data gathered from GPS-collared livestock hold potential for increasing knowledge of factors driving livestock aggregation patterns, but advances in gathering the data have outpaced advancements in analyzing and learning from it. We fit a hierarchical seemingly unrelated regression (SUR) model to explore how season of stocking and the location where cattle entered a pasture influenced grazing distributions. Stocking alternated between summer on one side of the pasture one year and fall on another side of the pasture the next year for 18 years. Waypoints were recorded on cattle for 50 d each year. We focused our analysis on the pasture's 10 most heavily grazed 4-ha units, because these units were the most prone to negative grazing impacts. Though grazing of the study units was always disproportionately heavy, it was much heavier with the summer than fall stocking regime: Bayesian confidence intervals indicate summer grazing of study units was approximately double the average fall grazing value. This is our core result, and it illustrates the strong effect stocking season or date or both can have on grazing distributions. We fit three additional models to explore the relative importance of stocking season versus location. According to this analysis, stocking season played a role, but stocking location was the main driver. Ostensibly minor factors (e.g. stocking location) can greatly influence livestock distributions.  相似文献   
239.
土壤是人类赖以生存的基本要素之一,然而随着我国经济社会的发展,土壤环境污染日益严重,已威胁到各种陆生动植物的生态平衡。为落实环保部《关于加强土壤污染防治工作的意见》要求,2006年云南省土壤污染调查全面启动。系统运用Microsoft Visual Basic作为开发语言,SQL Server作为数据库,Arc GIS作为地图开发工具,来完成数据的导入和校验,统计、评价和对比的分析与查询,以及各类统计图表的自动生成。系统开发解决了庞大数据的管理与分析问题,对数据进行了生动的图表化表示并通过数据自动更新机制,简化了数据的管理工作,提高了《云南省土壤环境质量报告》的编制效率,对各级管理部门的决策工作具有较大的辅助意义。  相似文献   
240.
基于数据场和云模型的洪水灾害风险等级评估   总被引:2,自引:1,他引:1  
根据灾害风险系统的定义以及洪水灾害的特点,用灾情损失与地形危险性的综合作用描述洪水灾害风险。针对研究单元风险的内在联系和等级概念的模糊性、随机性,提出基于数据场和云模型的洪水灾害风险等级评估方法,以期为洪水灾害风险管理提供科学依据。以苏州市和上海市(崇明县除外)为例,首先用数据场对灾情数据进行扩散;再用云模型对地形进行等级划分;最后对两者进行耦合得到该地区的洪水灾害风险等级划分。结果表明:苏州市中心偏北区域和上海市中心区域综合风险等级最高,并向四周呈递减趋势;总体上中部风险等级最高,北部次之,南部最低。  相似文献   
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