Quantification of suspended solids in Dal lake,Srinagar using remote sensing technology

Indian Remote Sensing satellite (IRS)-1B, Linear Imaging Self Scanner (LISS)-II spectral digital data was analysed to determine the feasibility of quantifying the concentration of suspended solids in the surface water of inland water body, Dal lake, in Srinagar, India. The water samples collected in concurrent with IRS-1B overpass, were analysed to determine the concentration of suspended solids. The results indicate that a positive functional relationship exist between the concentration of suspended solids and the visible wave length bands 1 and 3 and near infrared band 4. It has been observed that as the concentration of suspended solids increase, the spectral response also increases. It is concluded that IRS LISS-H data can be effectively used to quantify suspended sediment concentration in the Dal lake surface water.     

玻璃微珠折射率测定

提出了一种测量直径小于1mm的玻璃珠折射率的新技术,其精度可达10-4,比常规的浸液法测量方便而又精确.     

绵阳市涪城区近十年土地利用动态监测及分析

近年来绵阳市土地利用变化现象表现十分明显,但缺乏比较深入的研究。本文根据绵阳市涪城区2000年和2010年的土地利用变化动态监测数据,利用CA-Markov模型对2020年的土地利用空间格局进行预测,并对引起该区土地利用变化的驱动力进行分析。     

基于车载激光雷达的行道树提取研究

对车载激光雷达点云数据进行研究,提出了一种分层投影的方法提取行道树,该方法对点云数据进行分层投影,利用不同高程点云投影后表现出的不同特征,采用面向对象的方法对行道树进行提取,最后叠加分析得到行道树点云。实验证明,该方法能够比较完整的提取出行道树点云。     

平衡施肥对棉麦套作中小麦生长发育的影响

根据田间区试结果,分析了有机肥与氮磷钾化肥配施对棉麦套作中小麦生物产量和经济产量的构成因素、养分含量及吸收量的影响,结果表明:有机肥与化肥配施能显著提高小麦的生物产量和经济产量,且以中肥最为适宜;增施氮磷钾肥能提高小麦各生育期养分含量和吸收积累量,并且还能增加旗叶的叶面积和叶绿素含量.小麦营养生殖并重时期(拔节至孕穗期),对养分的需求量大,此时土壤中足够的养分,可为小麦高产优质奠定营养基础,此期也是小麦平衡施肥的关键时期.     

Stability of richterite50-tremolite50 solid solution at high pressures and possible presence of sodium calcic amphibole under upper mantle conditions

High pressure experiments have been made on the stability of richterite₅₀-tremolite₅₀ solid solution by the piston-cylinder type high pressure apparatus in the pressure range from 15 to 40 kb, at temperatures from 700 to 1150°C. This amphibole is stable up to 40 kb at 700°C, and the breakdown pressure gradually decreases with increasing temperatures. It is suggested that this amphibole, on the basis of high pressure experiments, may occur in the upper mantle.     

On the Distance Function Between Two Keplerian Elliptic Orbits

The problem of finding critical points of the distance function between two Keplerian elliptic orbits is reduced to the determination of all real roots of a trigonometric polynomial of degree 8. The coefficients of the polynomial are rational functions of orbital parameters. Using computer algebra methods we show that a polynomial of a smaller degree with such properties does not exist. This fact shows that our result cannot be improved and it allows us to construct an optimal algorithm to find the minimal distance between two Keplerian orbits. This revised version was published online in July 2006 with corrections to the Cover Date.     

Non-symmetrical levee breaching processes in a channel bend due to overtopping

A series of experiments were done to reveal the overtopping breaching process of non-cohesive and cohesive levees in a U-bend flume. The flood hydrograph and breaching geometry were measured and analyzed in detail. The results show that the levee breaching processes can be briefly divided into four stages: slope erosion, longitudinal headward gully-cutting, lateral erosion, and relative stabilization. For non-cohesive levees, non-symmetrical lateral development of the breach occurs throughout the four stages, and the final non-symmetrical coefficient is approximately 2.2–2.6. Larger flow discharge or higher water level can accelerate the breaching process, while coarser sands tend to accelerate the process initially but depress the process at the end. The fluvial erosion rate of a non-cohesive breach shows a power-function relation with the excess wall shear stress. For cohesive levees, a plateau forms in the breach partially blocking the flow in the first two stages. The breach flow is approximately perpendicular to the levee body, and, thus, the erosion rates of the two breach sides are almost the same. Non-symmetrical lateral development mainly occurs in the third stage when the deep gully forms. The final non-symmetrical coefficient is approximately 2.7–3.3. It is expected that these findings can provide a valuable experimental dataset and a theoretical basis for breach closure and flood alleviation.     

Evaluation of significant sources influencing the variation of physico-chemical parameters in Port Blair Bay,South Andaman,India by using multivariate statistics

Port Blair is the capital city of Andaman & Nicobar Islands, the union territory of India. More than 50% of the population of these islands lives around Port Blair Bay. Therefore the anthropogenic effects in the bay water were studied for monitoring purpose from seven stations. Physico-chemical parameters of seawater were analyzed in samples collected once in every 3 months for 2 years from seven sampling stations located in Port Blair Bay, South Andaman Island to evaluate the spatial and tidal variation. Cluster analysis and factor analysis were applied to the experimental data in an attempt to understand the sources of variation of physico-chemical parameters. In cluster analysis, the stations Junglighat Bay and Phoenix Bay having high anthropogenic influence formed a separate group. The factors obtained from factor analysis indicated that the parameters responsible for physico-chemical variations are mainly related to land run-off, sewage outfall and tidal flow.