Bianchi type – IX string cosmological models with bulk viscous fluid in general relativity

Some Bianchi Type IX string cosmological models with bulk viscous fluid for massive string is investigated. To get a determinate solution, a supplementary condition a=b ⁿ, between metric potentials, is used wherea and b are function of time alone. A particular solution for n=0 is also discussed. The behaviour of the model in presence and absence of bulk viscosity, is discussed. The physical and implications of the model is also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparison of TOPEX/POSEIDON Altimeter Derived Wind Speed and Wave Parameters with Ocean Buoy Data in the North Indian Ocean

Results of comparison exercises carried out between the state-of-the-art TOPEX/POSEIDON altimeter-derived ocean surface wind speed and ocean wave parameters (significant wave height and wave period) and those measured by a set of ocean data buoys in the North Indian Ocean are presented in this article. Altimeter-derived significant wave height values exhibited rms deviation as small as ±0.3 m, and surface wind speed of ±1.6 m/s. These results are found consistent with those found for the Pacific Ocean. For estimation of ocean wave period, the spectral moments-based semiempirical approach, earlier applied on GEOSAT data, was extended to TOPEX/POSEIDON. For this purpose, distributions of first four years of TOPEX/POSEIDON altimeter data and climatology over the North Indian Ocean were analyzed and a new set of coefficients generated for estimation of wave period. It is shown that wave periods thus estimated from TOPEX/POSEIDON data (for the subsequent two years), when compared with independent data set of ocean data buoys deployed in the North Indian Ocean, exhibit improved accuracy (rms ~ ±1.4 nos) over those determined earlier with GEOSAT data.     

The flow of viscoelastic non-Newtonian fluid in the Ekman layer

In this paper the unsteady flow in the Ekman layer of a visco-elastic non-Newtonian fluid near a flat plate is discussed. Laplace transform technique has been employed to show the basic differential equations. Expressions for velocity profile, the skin friction have been calculated. It is shown that the time to attain the steady state increases with the elastic parameter. It is shown that normally the ultimate steady state is reached through a decay of inertial oscillations whose frequency decreases with increase in the elastic parameter. In the present study we examine the following unsteady problem in non-Newtonian fluid. Consider an infinite plate coinciding with the platez=0 and rotating in unison with elasticoviscous liquid occupying the regionz>0 with a uniform angular velocity about thez-axis for timet<-0. At timet>0, the plate starts moving with a uniform velocityU _o along thex-axis relative to the rotating frame of reference. The horizontal homogeneity of the problem demands that conditions depend onz andt only. The equation of continuity together with the no slip condition at the plate then shows that thez-component of the velocity vanishes everywhere.     

The structure of rotating polytropes (second order)

In order to carry out a numerical study of the structure of rotationally distorted polytropes, the Monaghan and Roxburgh (1965) method is extended to include the second-order term in the perturbation parameter, .     

Classification and interpretation of piezometer well hydrographs in parts of southeastern peninsular India

Well hydrographs from 275 piezometers between 1998 and 2001 in the southeastern parts of peninsular India were used in this study. The area has a monsoon-type climate. Hard rocks cover 85% of the area. The form (shape) of the hydrograph depends upon (1) climatic and hydrogeologic parameters and (2) the scale of the graph. Therefore, hydrographs are drawn to a defined and standardised scale, which allows comparison of hydrographs and helps in bringing out reasons for different forms of the hydrographs. Hydrographs can be divided into seasonal segments and the slope of each segment then used as the basic element of a classification scheme. Slopes are classed as flat (inclination <20°), obtuse (between 20 and 45°), acute (45 and 80°), right angled (80 and 90°) and homoclinal (segments of hydrographs are either rising or falling during one complete water year). Hydrographs are assigned names that are a combination of these classes and begin with the rising segment, such as acute-obtuse. Seventy-six percent of segments were homoclinal-falling in 1999, which had a poor monsoon. Flat segments constitute 27% of all segments in confined Mesozoic aquifer systems. Water table fluctuations suggest an approximate recharge of 120 to 180 mm per annum constituting 18% of the annual precipitation. Cumulative rainfall required to affect a rise in water table is between 45 to 200 mm and lag time varies from 30 minutes to 200 rainy days, which suggests that moisture in the vadose zone holds a part of the annual replenishment for these aquifers.     

外资和尼泊尔本土能源项目建设状况遥感对比监测研究（英文）

外资在发展中国家水电站建设中发挥着重要作用。外资在水电站建设过程中会遇到哪些新问题,已成为国际投资者关注的重要问题之一。为了解决这一问题,本文比较了尼泊尔上崔树里3A水电站（由中国政府银行全额出资）和拉苏瓦加迪电站（由尼泊尔拉苏瓦区当地政府银行出资）的建设情况。利用道路、建筑物、大坝和车辆等指标,采用目视判读方法,从2012年至2020年的1m分辨率高分遥感影像中提取监测指标,对比监测两座水电站的建设情况。采用两种方法对比监测了两座电站建设对生态环境的影响。首先,在两个电站建设期内（上崔树里3A水电站监测周期为2012年至2020年,拉苏瓦加迪电站监测周期为2014年至2020年）,利用30 m Landsat 7/8卫星数据,对比评估了两座电站建设期内的归一化植被指数变化情况。然后,利用1 m分辨率高分遥感影像,采用目视判读方法,对比监测两座电站周边的土地利用变化情况。最后,分析和比较影响这两个电站施工过程、环境影响和社会经济影响的因素。结果表明：（1）尽管地质灾害、新冠疫情、印度政府禁令等诸多因素影响了尼泊尔各项目的建设,中国投资的上崔树里3A水电站与尼泊尔本土投资的拉苏瓦加迪电站...