膜生物反应器处理难降解废水的特性研究   总被引：3，自引：3，他引：0  

张凤君  赵芝清  周秀清  苏克  周海林  于广菊 《吉林大学学报(地球科学版)》2005,35(6):786-789,795

膜生物反应器与生物接触氧化法处理难降解废水的对比研究表明,在相同的运行条件下,膜生物反应器比生物接触氧化法具有更稳定的出水水质,其平均出水COD_cr去除率达到88.41%,比接触氧化法提高了近30%;其平均色度去除率达到85.27%,相比接触氧化法,提高了近30%。通过出水分子量组成分析发现,膜出水以分子量介于3 000和10 000之间的物质为主,占总数的88.36%,接触氧化以分子量大于10 000的物质为主,占总物质的72.04%,介于3 000和10 000之间的仅占9.76%。  相似文献   

加权多点灰色模型在高边坡变形预测中的应用   总被引：1，自引：0，他引：1  

何习平  华锡生  何秀凤 《岩土力学》2007,28(6):1187-1191

边坡变形是一个复杂的系统过程,单点模型GM(1,1)不能考虑各变形监测点间的相关性。针对单点模型背景值取值方法的不足,提出一种动态定权方法,建立加权多点灰色预测模型(即WM-GM(1,1 )模型)。利用Matlab语言编写了程序,实例计算表明,WM-GM(1,1 )模型预测精度高。  相似文献   

沙漠化地区可持续发展评价:Ⅱ.应用   总被引：2，自引：2，他引：0  

包慧娟  李振山  王涛 《中国沙漠》2006,26(3):440-446

采用层次分析方法并结合沙漠化具体特征给出了沙漠化评价指标的权重计算方法,并以奈曼旗为例详细说明了沙漠化地区的可持续发展评价过程。结果表明,基于沙漠化治理提出的可持续发展评价体系较准确地反映了沙漠化地区影响可持续发展的关键因素,提出的评价方法也行之有效,评价结果可以为当地的可持续发展提供建议。从1975—2000年,奈曼旗地区可持续发展水平逐步提高,沙漠化程度不断减轻,人类活动和社会经济条件基本呈好转趋势,自然条件波动较大。进一步的发展措施可归纳为：调节人类活动以适应脆弱的自然条件,改善社会经济条件以改变不合理的人类活动等。  相似文献   

210Pb in a tropical coastal lagoon sediment core     

F. Páez-Osuna  Enrique F. Mandelli 《Estuarine, Coastal and Shelf Science》1985,20(3):367-374

Excess ²¹⁰Pb in a core from a Mexican Coastal Lagoon, which has no connection with the sea shows a small but measurable decay over the length of the core, when different approaches were compared (excess and corrected ²¹⁰Pb activity with depth, total and inorganic cumulative weights) significant differences in the values for the sedimentation rate are obtained. The best coefficient correlation was calculated when corrected ²¹⁰Pb activity for the uneven distribution of organic matter and cumulative inorganic weight is considered ($\text{ω}\text{= 0·93 cm yr}{}^{\mathrm{?1}}$, R = ?0·86; ω = 0·51 cm yr^?1 for the top 13 cm, R = ?0·90 and 1·52 cm yr^?1 for the interval 14–46 with R = ?0·96).Time frames in the sedimentary column were in agreement between the ²¹⁰Pb calculated time and the appearance of shells fragments probably associated with the disturbances caused by the 1961 hurricane Tara.The surface accumulation rate is equivalent to a mean deposition of 262·5 g m^?2 yr^?1 or organic matter which is minor but comparable to some salt marshes of United States.  相似文献   

Error sources of precipitation measurements using electronic weight systems   总被引：1，自引：0，他引：1  

B. Sevruk  B. Chvíla   《Atmospheric Research》2005,77(1-4):39

Liquid precipitation amounts below 0.05 mm in combination with intervals of measurement greater than 3 min and temperature above 15 °C can considerably affect the measured precipitation using electronic weighing gauges. This was shown by tests using different weights put in the gauge in different intervals in order to simulate different precipitation amounts and measuring intervals. These results were confirmed by field intercomparison measurements using pit gauges in two locations in Slovakia. In total, 1571 weight tests consisting of combinations of simulated precipitation amounts of 0.025, 0.05, 0.2 mm and measuring intervals of 1, 2, 3, 5 and 10 min were carried out. Based on these tests and special software, a new gauge was developed. Using this gauge, the abovementioned error sources were minimized. The Slovak Hydrometeorological Institute now uses it at 90 gauge sites. This type of gauge was selected to participate in the current World Meteorological Organization, WMO, Intercomparison measurements of recording precipitation gauges.  相似文献   

基于双正交多小波的SAR与可见光图像融合研究   总被引：1，自引：3，他引：1  

洪日昌  吴秀清  杨浩 《测绘信息与工程》2006,31(2):1-3

针对已有的数据融合技术,提出了一种基于双正交多小波变换的遥感图像融合算法,采用了邻域方差准则和非线性加权相结合的方法,分别融合小波低频和高频系数,试验选取星载SAR与SPOT可见光图像进行融合,实现了很好的融合效果。  相似文献   

单位权方差公式的统一推证     

郭宗河  郑进凤 《测绘科学与工程》2006,26(1):29-31,40

本文从二次型的期望公式出发，推导了经典最小二乘平差、最小二乘滤波、最小二乘推估和最小二乘配置的验后单位权方差的估计公式。  相似文献   

The Application of Artificial Neural Networks to Landslide Susceptibility Mapping at Janghung, Korea   总被引：13，自引：0，他引：13  

Saro Lee  Joo-Hyung Ryu  Moung-Jin Lee  Joong-Sun Won 《Mathematical Geology》2006,38(2):199-220

The purpose of this study was to develop techniques for landslide susceptibility using artificial neural networks and then to apply these to the selected study area at Janghung in Korea. Landslide locations were identified from interpretation of satellite images and field survey data, and a spatial database of the topography, soil, forest, and land use. Thirteen landslide-related factors were extracted from the spatial database. These factors were then used with an artificial neural network to analyze landslide susceptibility. Each factor's weight was determined by the back-propagation training method. Five different training sets were applied to analyze and verify the effect of training. Then the landslide susceptibility indices were calculated using the back-propagation weights, and susceptibility maps were constructed from Geographic Information System (GIS) data for the five cases. Landslide locations were used to verify results of the landslide susceptibility maps and to compare them. The artificial neural network proved to be an effective tool for analyzing landslide susceptibility.  相似文献   

堤防工程安全评估专家赋权模型   总被引：4，自引：0，他引：4  

顾冲时  汪自力  刘成栋 《岩土力学》2006,27(12):2099-2104

针对堤防工程安全影响因素多，影响因素既有定量又有非定量指标，并且存在指标的模糊性和不确定性等特点的问题；利用模糊数学和模式识别理论以及动态聚类方法等，提出了堤防工程安全评估专家主观和客观赋权模型：在此基础上，还提出了融合专家主观和客观权重的堤防工程安全评估专家综合赋权模型。并用实例对所提出的模型进行了验证。  相似文献   

南海北部灾害地质稳定度评价模型     

杨春霞  王春民  王圣洁 《中国地质灾害与防治学报》2006,17(1):77-79

海洋经济的开发需要了解海洋灾害地质环境状况。海洋工程设计与建设需要考虑海底工程地质条件,特别是国家宏观决策更需要了解海洋地质环境的基本特征以及灾害地质类型、分布规律。灾害地质综合评价可以基于灾害地质分区进行,灾害地质综合评价的目标是比较不同分区的灾害地质稳定性并给出定量评价。文中就南海北部灾害地质稳定性提出了网格化加权统计模型。该模型结合专家智能的参与,体现了不同种类灾害地质因素的等级差别。另外还考虑到不同种类灾害地质因素之间的空间分布差异性及同类灾害地质因素的空间分布差异性。根据模型计算结果将评价区划分为稳定区、过渡区及危险区。这种划分通过与南海北部灾害地质稳定性定性描述对比。证明该模型在全面地定量化反映南海北部的地质环境状况方面是实用的。由于模型建立过程中各灾害因素权重分值的设定完全依赖于专家智能,因此,今后应当致力于更精确地确定权重分值。  相似文献