Center for Environmental Sciences & Engineering

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Shiv Nadar University

Submerged vanes are submerged foils of low height (H) and higher length (L) structures, which are constructed in river at an angle of attack to the flow to modify the near-bed flow pattern and redistribute flow and sediment transport within the channel cross-section. The aspect ratio of submerged vane is defined as H/L. The aspect ratio of submerged vane is one of the most important parameters which influences the generation of strength of vane induced secondary circulation. At 2.5H downstream of vane, dimensionless moment of momentum MOM*, MOM**, MOM*** increase with the reduction in aspect ratios of submerged vane. The strength of vortex induced by vane among three values of aspect ratios such as 0.25, 0.33 and 0.50, is maximum at lowest aspect ratio 0.25. At lowest aspect ratio, the maximum value of vane-induced strength of vortex led to the increased deposition of sediments (dike). Generation vortex starts right from the leading edge and it is amplified till it reaches the trailing edge of submerged vane due to increase in vane length.

World University root node

Water and Energy International

Performance evaluation of aspect ratio of submerged vanes

At optimal angle of attack, vanes have the maximum strength of secondary circulation. For the same hydraulic condition, the maximum strength of vane induced secondary circulation also depends on their shapes. Optimal angle of attack in case of rectangular submerged vane with collar is very close to 40° where as in case of double curve vane type I, double curve vane type II, J1 type and J2 type vane is very close to 45°. Strength of vane induced secondary circulation in terms of moment of momentum depends upon various parameters. A dimensional analysis approach has been attempted to get dimensionless moment of momentum. The maximum strength of vane induced secondary circulation in terms of dimensionless moment of momentum is greater in case of rectangular vane than that in case of curved vanes in the same flow conditions and same height and length of vanes. © 2006 Taylor & Francis Group, LLC.

ISH Journal of Hydraulic Engineering

Vorticity with different shapes of submerged vanes

The forecast of a hydrological time series has been one of the most complicated tasks due to wide range of data, uncertainties in the parameters influencing it and lack of adequate data. Feed forward multilayer neural networks are widely used as predictors in aquatic fields of applications. The paper demonstrates the potential of artificial neural network (ANN) models for simulating and forecasting daily river stages at Pandu, Pancharatna and Dhubri gauging sites of the river Brahmaputra. Back propagation method has been chosen. The main purpose has been the modelling of the river Brahmaputra. in àmulti gauging station catchment and real time forecast of daily stage downstream. Model efficiency of all the networks override the conceptual idea of use of the ANN has been clearly articulated.

Application of artificial neural network for daily river stage forecast in the river Brahmaputra

The strongest circulation gives the maximum effects of submerged vanes at optimal angle of attack and at the same time local scour holes develop around the submerged vanes, which may dislodge the submerged vanes. With the introduction of collar or riprap with geo-filter at the leading edge of submerged vane, the local scour may be reduced. A comparison of the cost of riprap with geo-filter and collar has been attempted to get a general idea of economics. This paper explains theoretically how to compare the cost of riprap with geo-filter and collar.

Economic analysis: Riprap with geo-filter vs collar as scour protections around submerged vanes

For spacing of vane arrays, the information about strength of vortex downstream of a submerged vane is needed. A series of experiments were performed with rectangular submerged vane with and without a collar at Froude numbers 0.13 and 0.25. To define the strength of vortex, a new set of dimensionless parameters using moment of momentum are involved. The present study provides certain information on the decay of strength of vortex with downstream of vane. The decay of vane strength does not follow similar trend and appears sensitive to the location of center of vortex, Froude number, etc. The streamwise spacing of submerged vanes may be taken at least 40H at optimal angle of attack. Centre of vortex is also observed to change with the downstream of submerged vane. © 2006 Taylor & Francis Group, LLC.

Decay of strength of vortex down stream of submerged vane

The study attempts to undertake a comparison of methods of analysis for raft foundation of a barrage especially involving two methods, viz., Hetenyi's beams on elastic foundation method and Finite Element Method (FEM). In the analysis of barrage raft, moments at different discrete points along the raft of barrage have been calculated by Hetenyi's method and FEM, and their comparison has been made for typical representative cases only considering flow and no flow conditions incorporating earthquake loads as pseudo-static loads. Significant differences have been observed in the moments as obtained by the two methods. The end of the barrage raft where pier is located, the Hetenyi's method gives positive moments while FEM has yielded negative moments. It has also been observed from the results that Hetenyi's method of analysis may not be always on conservative side in comparison to FEM. The comparative analyses indicate that the IS 11130-1984 recommendation regarding Hetenyi's method (Beams on elastic foundation) merits further in vestigation.

Comparative study on analysis of barrage raft by Hetenyi's method and FEM

Phenylarsenic(III) dimethoxide derivatives of substituted benzothia-zolines having the general formula PhAs(OMe)2[N(H)C6H4SCR(R)′] where R = CH3, R′ = CH3 (1), R = C2H 5, R′ = C2H5 (2), R = H, R′ = C6H5 (3), R = CH3, R′ = C 6H5 (4) R = CH3, R′ = C6H 4CH3-4 (5), R = CH3, R′ = C 6H4Cl-4 (6), have been synthesized by the reaction of PhAs(OMe)2 (prepared in situ) with substituted benzothiazolines in a 1:1 molar ratio in refluxing benzene solution. These newly synthesized complexes have been characterized by elemental analysis and molecular weight measurements. The spectral studies IR, 1H and 13C NMR show the formation of the additional products in which the nitrogen atom of the benzothiazoline-ring coordinate to the central arsenic atom. A distorted trigonal bipyramidal geometry around arsenic atom has been tentatively proposed for these derivatives. Copyright {\textcopyright} Taylor & Francis Inc.

Phosphorus, Sulfur and Silicon and the Related Elements

Synthesis and characterisation of additional products of phenylarsenic(III) dimethoxide with substituted benzothiazolines

Indian Journal of Agricultural Research

Effect of different Rhizobium isolates, soil pH and moisture on growth of provenances of Acacia auriculiformis

Kerala Forest Research Institute

Heartwood and natural decay resistance in plantation grown (Tectona grandis Lf) from Togo, West Africa

Majuli, the world's largest river island, is situated to the north of Jorhat in India and at the confluence of the Subansiri and Brahmaputra rivers. Flooding ravages the population of 0.13 million every year, robbing them of the basic requirements of life. This island, which was over 1245 km2 in the 1950s, was reduced to 376.93 km2 in 2002 due to continuous erosion of banks by the Brahmaputra river, wiping out scores of villages and displacing thousands of people. The heritage of the people of Majuli, the civilization they have nurtured for the last five centuries, is about to be buried. Burial of this civilization will be a loss to the whole of humanity. Therefore, a global approach to this problem of flooding and subsequent erosion has become inevitable, and is urgently needed to save the world's largest river island as well as its glowing cultural heritage. This paper focuses on the study of erosion problems of the decaying island, deploying remote sensing and an artificial neural network (ANN) technique. © 2005 Taylor &amp; Francis Group, LLC.