Application of the meshless procedure for the elastoplastic torsion of prismatic rods

In this paper torsion of prismatic bars considering elastic-plastic material behavior is studied. Based on the Saint-Venant displacement assumption and the Romberg-Osgood model for the stress-strain relation, the boundary value problem for stress function is formulated. In reality an area of cross section of a bar has two regions: elastic with linear governing equation and plastic with non-linear governing equation. In the solution procedure, the meshless procedure based on the Homotopy Analysis Method HAM connected with the Method of Fundamental Solutions (MFS) and Radial Basis Functions (RBF) is applied. The considered nonlinear partial differential equation (PDE) is transform into a hierarchy of linear inhomogeneous PDEs. The accuracy of the obtained approximate solution is controlled by the number of components of the calculate solution, while the convergence of the process is monitored by an additional parameter of the method. The advantage of the proposed meshless approach is that it does not require the generation of a mesh on the domain or its boundary, but only using a cloud of arbitrary located nodes

Application of the method of fundamental solutions for inverse problems related to the determination of elasto-plastic properties of prizmatic bar

The problem of determining the elastoplastic properties of a prismatic bar from the given relation from experiment between torsional moment MT and angle of twist per unit of rod’s length θ is investigated as inverse problem. Proposed method of solution of inverse problem is based on solution of some sequences of direct problem with application of the Levenberg-Marquardt iteration method. In direct problem these properties are known and torsional moment as a function of angle of twist is calculated form solution of some non-linear boundary value problem. For solution of direct problem on each iteration step the method of fundamental solutions and method of particular solutions is used for prismatic cross section of rod. The non-linear torsion problem in plastic region is solved by means of the Picard iteration

The Copper, Iron, Zinc, Magnesium, Manganese, and Calcium Content of the Western Basin of Lake Erie

Author Institution: Department of Microbiology, The Ohio State UniversityWater samples from the western basin of Lake Erie were filtered to restrain suspended particles larger than 4 /xm and were analyzed for copper, iron, zinc, manganese, magnesium, and calcium by atomic absorption spectrophotometry. Samples were collected at weekly intervals during July-August and with less frequency in September, October and November (1970). Mean seasonal and range of concentrations for elements considered did not vary with depth. Mean seasonal and range of concentrations for soluble elements from 4.5 m depth were (/xg/ml): copper, 0.091 (0.04-0.20); iron, 0.284 (0.06-0.050); zinc, 0.087 (0.00-0.11); manganese, 0.039 (0.025-0.003); magnesium, 10.38 (6.54-13.54); and calcium, 35.78 (30.30-43.60). Solvent extracted elements from suspended particulates were present in mean seasonal and range of concentrations (/ug/ml) for copper, 0.014 (0.003-0.038); iron, 0.550 (0.30-1.00); and zinc, 0.050 (0.020-0.150). Manganese content was below detectable limits, while magnesium and calcium were non-extractable. Except for calcium, the mean seasonal concentration varied for elements considered from those reported previously for either Lake Erie or for the western basin. A close association existed between the levels of soluble and particulate copper, iron and zinc

Effect of a skin-deep surface zone on formation of two-dimensional electron gas at a semiconductor surface

Two dimensional electron gases (2DEGs) at surfaces and interfaces of semiconductors are described straightforwardly with a 1D self-consistent Poisson-Schr\"{o}dinger scheme. However, their band energies have not been modeled correctly in this way. Using angle-resolved photoelectron spectroscopy we study the band structures of 2DEGs formed at sulfur-passivated surfaces of InAs(001) as a model system. Electronic properties of these surfaces are tuned by changing the S coverage, while keeping a high-quality interface, free of defects and with a constant doping density. In contrast to earlier studies we show that the Poisson-Schr\"{o}dinger scheme predicts the 2DEG bands energies correctly but it is indispensable to take into account the existence of the physical surface. The surface substantially influences the band energies beyond simple electrostatics, by setting nontrivial boundary conditions for 2DEG wavefunctions.Comment: 9 pages, 7 figures, 2 table

History of Microbiology at The Ohio State University, 1873-1969

Prepared for the Centennial of The Ohio State University