Coarsening Strategies for Unstructured Multigrid Techniques with Application to Anisotropic Problems

Over the years, multigrid has been demonstrated as an efficient technique for solving inviscid flow problems. However, for viscous flows, convergence rates often degrade. This is generally due to the required use of stretched meshes (i.e., the aspect ratio AR = Δy/Δx < < 1) in order to capture the boundary layer near the body. Usual techniques for generating a sequence of grids that produce proper convergence rates on isotropic meshes are not adequate for stretched meshes. This work focuses on the solution of Laplace's equation, discretized through a Galerkin finite-element formulation on unstructured stretched triangular meshes. A coarsening strategy is proposed and results are discussed

UTILIZATION OF CONVENTIONAL AND NON-CONVENTIONAL ORGANIC SOURCES AND INDUSTRIAL BY-PRODUCTS FOR YIELD MAXIMIZATION OF BRINJAL IN COASTAL SOIL

This study was conducted to evaluate the response of brinjal (Solanum melongena L.) with conventional, non-conventional organic source, industrial by-products combined with inorganic fertilizers. The treatments imposed were T1 – Control (100% RDF), T2-100% RDF + Municipal Solid Waste Compost @ 5 t ha-1, T3 – 100% RDF + Municipal Solid Waste Compost @ 10 t ha-1, T­4 – 100% RDF + Vermicompost @ 2.5 t ha-1, T5 – 100% RDF + Vermicompost @ 5 t ha-1, T6 – 100% RDF + Rice Husk Ash @ 5 t ha-1, T7 – 100% RDF + Rice Husk Ash @ 10 t ha-1, T8 – 100% RDF + Lignite Fly Ash @ 5 t ha-1, T9 – 100% RDF + Lignite Fly Ash @ 10 t ha-1. There were nine treatments combinations replicated thrice in CRD. The soil was sandy in texture with available nitrogen, phosphorus and potassium of 257, 10.2 and 117 kg ha-1 respectively which fell in fertility status of low. The soil classified taxonomically as Typic Udisamments. The results showed that application of 100% RDF + Vermicompost @ 5 t ha-1 (T5) significantly increased yield attributes viz., fruit length (16.6 cm), fruit girth (15.2 cm), no. of fruits plant-1 (20.67), fruit weight (45.2 g) and fruit yield plant-1 (934.2 g plant-1). This treatment registered maximum quality attributes like ascorbic acid content (4.5 mg 100 g-1), crude protein (4.81%), drymatter of fruit (70.2 g plant-1) and dry matter of plant (81.3 g plant-1). The post harvest soil available N (148mgkg-1) and P (7.15mgkg-1)status was higher due to application of 100% RDF with Vermicompst @ 5 t ha-1 (T5).&nbsp; The post harvest available K (75.58mgkg-1) status recorded higher in the treatment T9 which received 100% RDF with Lignite Fly Ash @ 10 t ha-1 (T9)

A STUDY OF TRENDS IN B2C ONLINE BUYING IN COIMBATORE DISTRICT

In today’s busy world online buying plays an important role in shopping. In this paper, an attempt has been made to find out the B2C online buying trends in Coimbatore district. .A sample of 100 respondents’ was conveniently selected from Coimbatore District. The selected samples are analyzed using simple percentage, chi-square test and correlation analysis test. It is found that four variables namely age, educational qualification, occupation and monthly income are found to be significant association with consumer satisfaction towards online buying. The study also concluded that educational qualification, occupation, monthly income have significant association with consumers preference towards B2C online buying

Agglomeration multigrid for viscous turbulent flows

Agglomeration multigrid, which has been demonstrated as an efficient and automatic technique for the solution of the Euler equations on unstructured meshes, is extended to viscous turbulent flows. For diffusion terms, coarse grid discretizations are not possible, and more accurate grid transfer operators are required as well. A Galerkin coarse grid operator construction and an implicit prolongation operator are proposed. Their suitability is evaluated by examining their effect on the solution of Laplace's equation. The resulting strategy is employed to solve the Reynolds-averaged Navier-Stokes equations for aerodynamic flows. Convergence rates comparable to those obtained by a previously developed non-nested mesh multigrid approach are demonstrated, and suggestions for further improvements are given

A 3D agglomeration multigrid solver for the Reynolds-averaged Navier-Stokes equations on unstructured meshes

An agglomeration multigrid strategy is developed and implemented for the solution of three-dimensional steady viscous flows. The method enables convergence acceleration with minimal additional memory overheads, and is completely automated, in that it can deal with grids of arbitrary construction. The multigrid technique is validated by comparing the delivered convergence rates with those obtained by a previously developed overset-mesh multigrid approach, and by demonstrating grid independent convergence rates for aerodynamic problems on very large grids. Prospects for further increases in multigrid efficiency for high-Reynolds number viscous flows on highly stretched meshes are discussed

Unstructured multigrid through agglomeration

In this work the compressible Euler equations are solved using finite volume techniques on unstructured grids. The spatial discretization employs a central difference approximation augmented by dissipative terms. Temporal discretization is done using a multistage Runge-Kutta scheme. A multigrid technique is used to accelerate convergence to steady state. The coarse grids are derived directly from the given fine grid through agglomeration of the control volumes. This agglomeration is accomplished by using a greedy-type algorithm and is done in such a way that the load, which is proportional to the number of edges, goes down by nearly a factor of 4 when moving from a fine to a coarse grid. The agglomeration algorithm has been implemented and the grids have been tested in a multigrid code. An area-weighted restriction is applied when moving from fine to coarse grids while a trivial injection is used for prolongation. Across a range of geometries and flows, it is shown that the agglomeration multigrid scheme compares very favorably with an unstructured multigrid algorithm that makes use of independent coarse meshes, both in terms of convergence and elapsed times

Rhodium(I) complexes of α-keto-stabilised 1,2-bis(diphenylphosphino)alkane mono ylides

Rhodium(I) complexes of the hybrid ylide-phosphine ligands, Ph2P(CH2) n PPh2(CHC(O)C6H5) (n = 1: dppm-yl, or 2: dppe-yl) have been synthesised from [Rh(&#956;-C1)(COD)]2 (COD = 1,5-cyclooctadiene) and characterized by NMR spectroscopic and X-ray structural methods. The dppe-yl behaves as an ambidentate ligand; it functions as a monodentate P-donor ligand with a dangling ylidic carbon in the neutral chloro complex, [(COD)Rh(Cl)(dppe-yl)] (1), whereas replacement of the chloride by a non-coordinating counter anion results in the formation of the complexes, [(COD)Rh(L-L')]+ (L-L' = dppe-yl (2) or dppm-yl (3)) respectively in which the ligands are bonded to the metal via the phosphorus and the ylidic carbon atoms. The 1,5-cyclooctadiene (COD), present in the Rh(I) precursor, remains intact in the products. The structures of 1,2 and3 have been confirmed by X-ray crystallography

Sensitization of Gold Dust in 430 Grade Stainless Steel

\u27Gold dusting\u27 is a surface defect that is sometimes observed on cold-rolled AISI type 430 stainless steel. Gold dusting is characterized by a sparkling appearance, which results from small flakes of metal on the cold rolled surface, the flakes are mostly elongated in the rolling direction. The processing steps include continuous casting, hot rolling, continuous annealing, and pickling. One possibility is that the flakes of metal are grains that had been undercut by intergranular corrosion such intergranular corrosion may occur during pickling after the annealing step (which itself follows hot rolling). If intergranular corrosion does occur during this pickling step, the intergranular cavities would be elongated by subsequent cold rolling; this can account for the observed morphology of gold dusting. If the steel has been sensitized, intergranular corrosion may occur during pickling. Pickling is commonly carried out by electrolytic descaling in a neutral sodium sulphate solution followed by immersion in a nitric acid/hydrofluoric acid bath. The sensitized type 430 stainless steel does, indeed, suffer intergranular corrosion in a nitric acid/hydrofluoric acid bath, while it is largely unaffected during electrolytic pickling. Hence, sensitization is a possible cause of gold dusting

Optimized differential TCDA (D-TCDA) with novel differential feed structure

Modern phased arrays require large instantaneous bandwidths, wide fields of view, and low profiles to conduct multiple functions. Many of these phased arrays rely on emerging high speed ADCs and advanced balanced transceivers. The benefits of balanced front-ends include improved linearity, dynamic range, isolation, and noise resilience. The application of a differential phased array in such a system removes extraneous losses caused by baluns, though the issue of feed-borne E-plane scan resonances must be considered. We address the E-plane scan resonance issue through an improved Balanced Wideband Impedance Transformer (BWIT) feed for the ultra-wideband (UWB) Tightly Coupled Dipole Array (TCDA). This BWIT feed has already demonstrated mitigated common-modes over a 3:1 bandwidth ratio while scanning to low angles. Here, our differential TCDA (D-TCDA) is developed for the L-C band (viz. 1.0 GHz to 6.1 GHz) with emphasis on resonance-free wide-angle scanning. Rigorous EM model and circuit analysis is included to verify the BWIT performance. Under a VSWR \u3c 3 definition, the improved array achieves a 6:1 impedance bandwidth ratio (BWR) with resonance-free scanning in all planes. An exception is the H-plane scanning at 60◦ where the VSWR \u3c 4. Array simulations are verified with measurements for an 8×8 single-polarized prototype