Effectiveness of Dichanthium annulatum in Watercourses for Reducing Sediment Delivery from Agricultural Watersheds          下载免费PDF全文

Battu Krishna Rao  Prasanta K. Mishra  Ravi S. Kurothe  Vinod C. Pande  Gopal Kumar 《洁净——土壤、空气、水》2015,43(5):710-716

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Application of direct displacement based design to long span bridges     

Gopal Adhikari  Lorenza Petrini  Gian Michele Calvi 《Bulletin of Earthquake Engineering》2010,8(4):897-919

The paper investigates the applicability of current direct displacement based seismic design (DDBD) procedure, developed by Priestley and his coworkers, for straight long span bridges under transverse seismic excitation synchronous to all supports. This category of bridges often possess some additional features such as massive tall piers, highly irregular distribution of mass and stiffness due to unequal superstructure spans and pier heights, large deformation capacity etc. that are absent in short-to-moderate span bridges for which DDBD has extensively been verified. It is shown that DDBD in its current form is unable to capture both displacement and base shear demand when compared with nonlinear dynamic analysis results. Accordingly, a simple mechanics based extension of the current procedure that takes into account the effect of pier mass while computing base shear demand as well as a modal combination rule for estimating displacement demand is proposed and validated using a series of parametric studies. The new procedure also allows engineer to allocate strength at the potential plastic hinge location in more general terms.  相似文献   

Oceanic upwelling and downwelling processes in waters off the west coast of India     

A. D. Rao  Madhu Joshi  M. Ravichandran 《Ocean Dynamics》2008,58(3-4):213-226

A three-dimensional model based on the Princeton Ocean Model (POM) has been implemented to study the circulation of the west coast of India. The model uses a curvilinear orthogonal horizontal grid with higher resolution near the coast (3–9 km) and a terrain following sigma coordinate in the vertical. The model is able to simulate Lakshadweep High and Lakshadweep Low (LL) during the winter and summer monsoons, respectively. During winter, the downwelling processes noticed along the coast help in the formation of temperature inversions. The inversions can be seen even up to the depths of ～50 m, which agrees with the available ARGO data in the region. Model simulations show that coastal upwelling off Kerala is at its peak in July. The intensity of upwelling reduces along the coast towards north. During the existence of LL, there is a cyclonic eddy in the sub-surface waters over the South-Eastern Arabian Sea, with vertical extent up to the depths of 100–150 m and it is strengthened due to the presence of northward counter current in the shelf region. The southerly coastal jet formed along the southern coast as a result of upwelling is noticed a westward shift along with LL. The location of the eddy off Kerala is tilted towards the open ocean with depth and our experiments suggest that this flow can be understood as a first baroclinic mode.  相似文献   

Tannery Effluents: Current Practices,Environmental Consequences,Human Health Risks,and Treatment Options     

Kavita Singh  Madhu Kumari  Kumar Suranjit Prasad 《洁净——土壤、空气、水》2023,51(3):2200303

The tannery industry influences the gross domestic product/economic activity of any country, but the uncontrolled release of tannery effluents causes environmental degradation and increases health risks to human. The reason for the toxicity of tannery effluents is the presence of high concentrations of organic and inorganic chemicals used in the production of leather goods. Untreated or partially treated effluents discharged into surface water results in an increase in both chemical and biological oxygen demand as well as in an increase in the levels of total suspended solids, dissolved solids, and toxic metals in environmental bodies, especially in soil, water bodies, and water sediments. Various treatment techniques, such as physicochemical, biological, and advanced oxidation methods, which include chemical precipitation, electrocoagulation, aerobic or anaerobic treatment, wetland construction, and Fenton, electro-Fenton, and photo-Fenton processes are also described. This review also discusses the technical appropriateness and economic feasibility of reducing the effluent pollution load and solid waste emanating from the tannery industry. Considering the enhanced health risks in the tannery waste treatment and management regime, some green and advanced technologies should be explored. A sustainable green technology that avoids the use of toxic chemicals in the tanning process is seen well for ecological health.  相似文献   

Optimal selection of representative climate models and statistical downscaling for climate change impact studies: a case study of Rhode Island,USA     

Shrestha  Shiva Gopal  Pradhanang  Soni M. 《Theoretical and Applied Climatology》2022,149(1-2):695-708

Theoretical and Applied Climatology - The future climate impact studies rely on future projections obtained from downscaling of Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models....  相似文献   

Satellite Image Resolution Enhancement Using Nonsubsampled Contourlet Transform and Clustering on Subbands     

S. S. Aneesh Raj  Madhu S. Nair  G. R. K. S. Subrahmanyam 《Journal of the Indian Society of Remote Sensing》2017,45(6):979-991

In this paper two new schemes for resolution enhancement (RE) of satellite images are proposed based on Nonsubsampled Contourlet Transform (NSCT). First one is based on the interpolation on band pass images obtained by applying NSCT on the input low resolution image. Similar to Demirel and Anbarjafari (IEEE Trans Geosci Remote Sens 49(6):1997–2004, 2011), as an intermediate step, the difference between approximation band and the input low resolution image is added with all the band pass directional subbands, to obtain a sharper image. This method is simple and computationally efficient but lacks sharp recovery of the edges due to the interpolation of band pass images. To overcome this, another method is proposed to obtain the difference layer, where dictionary is built using patches which are extracted from high resolution training image subbands. Similar patches from the dictionary are then clustered together. This method gives a much sharper image than the first method. Subjective and objective analysis of proposed methods reveals the superiority of the methods over conventional and other state-of-the-art RE methods.  相似文献   

Sea Level Variations Associated with Upwelling/ Downwelling Along the West Coast of India     

A. D. Rao  S. V. Babu  Madhu Sharma 《Marine Geodesy》2001,24(3):153-170

A three-dimensional numerical model is developed and used to study the coastal upwelling processes and corresponding seasonal changes in the sea level along the west coast of India. The upwelling and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. The model is designed to represent coastal ocean physics by resolving surface and bottom Ekman layers as realistically as possible. The prognostic variables are the three components of the velocity field, temperature, salinity and turbulent energy. The governing equations together with their boundary conditions are solved by finite-difference techniques. Experiments are performed to investigate sea level fluctuations associated with the thermal response and alongshore currents of the coastal waters. The model is forced with mean monthly wind stress forcing of January, May, July and September representing northeast monsoon and different phases of the southwest monsoon. It is known from the observational study that the upwelling process reaches to the surface waters by May along the coastal waters of the extreme southwest peninsular region. The process is more intense in July compared to May and September and its strength decreases from south to north. However, during the northeast monsoon season, which is represented by January wind stress forcing in the model, downwelling is simulated along the coast. The model simulations of the coastal response are compared with the observations and are found to be in good agreement. The maximum computed vertical velocity of about 2.0 ×10 -3 cm s -1 is predicted in July in the southern region off the coast.  相似文献   

Size segregated aerosol mass concentration measurements over the Arabian Sea during ICARB     

Vijayakumar S. Nair  K. Krishna Moorthy  S. Suresh Babu  K. Narasimhulu  L. Siva Sankara Reddy  R. Ramakrishna Reddy  K. Rama Gopal  V. Sreekanth  B. L. Madhavan  K. Niranjan 《Journal of Earth System Science》2008,117(1):315-323

Mass concentration and mass size distribution of total (composite) aerosols near the surface are essential inputs needed in developing aerosol models for radiative forcing estimation as well as to infer the environment and air quality. Using extensive measurements onboard the oceanographic research vessel, Sagar Kanya, during its cruise SK223B in the second phase of the ocean segment of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), the spatial distribution of the mass concentration and mass size distribution of near-surface aerosols are examined for the first time over the entire Arabian Sea, going as far as 58°E and 22°N, within a span of 26 days. In general, the mass concentrations (M _T ) were found to be low with the mean value for the entire Arabian Sea being 16.7 ± 7 μg m^?3; almost 1/2 of the values reported in some of the earlier campaigns. Coarse mode aerosols contributed, on an average, 58% to the total mass, even though at a few pockets accumulation mode contribution dominated. Spatially, significant variations were observed over central and northern Arabian Sea as well as close to the west coast of India. In central Arabian Sea, even though the M _T was quite low, contribution ofs accumulation aerosols to the total mass concentration was greater than 50%. Effective radius, a parameter important in determining scattering properties of aerosol size distribution, varied between 0.07 and 0.4 μm with a mean value of 0.2 μm. Number size distributions, deduced from the mass size distributions, were approximated to inverse power-law form and the size indices (ν) were estimated. It was found to vary in the range 3.9 to 4.2 with a mean value of 4.0 for the entire oceanic region. Extinction coefficients, estimated using the number-size distributions, were well-correlated with the accumulation mode mass concentration with a correlation coefficient of 0.82.  相似文献   

Skills of different mesoscale models over Indian region during monsoon season: Forecast errors     

Someshwar Das  Raghavendra Ashrit  Gopal Raman Iyengar  Saji Mohandas  M. Das Gupta  John P. George  E. N. Rajagopal  Surya Kanti Dutta 《Journal of Earth System Science》2008,117(5):603-620

Performance of four mesoscale models namely, the MM5, ETA, RSM and WRF, run at NCMRWF for short range weather forecasting has been examined during monsoon-2006. Evaluation is carried out based upon comparisons between observations and day-1 and day-3 forecasts of wind, temperature, specific humidity, geopotential height, rainfall, systematic errors, root mean square errors and specific events like the monsoon depressions.It is very difficult to address the question of which model performs best over the Indian region? An honest answer is ‘none’. Perhaps an ensemble approach would be the best. However, if we must make a final verdict, it can be stated that in general, (i) the WRF is able to produce best All India rainfall prediction compared to observations in the day-1 forecast and, the MM5 is able to produce best All India rainfall forecasts in day-3, but ETA and RSM are able to depict the best distribution of rainfall maxima along the west coast of India, (ii) the MM5 is able to produce least RMSE of wind and geopotential fields at most of the time, and (iii) the RSM is able to produce least errors in the day-1 forecasts of the tracks, while the ETA model produces least errors in the day-3 forecasts.  相似文献   

Understanding the life of bygone eras: Emerging trends     

Sandhya Misra  Krishna Gopal Misra 《Journal of the Geological Society of India》2014,83(4):471-471

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