Shape Optimization of Tunnel by Finite Element Method

The stresses around the periphery of tunnel openings are in general independent of factors such as size of the opening and elastic modulus of surrounding geotechnical material. The stresses however depend upon the shape of the opening and the residual stresses. At any point over the periphery the significant stresses are the normal stresses in the direction tangential to the opening periphery. By trials involving appropriate modifications to the finite element idealization, the shape of the opening could be derived such that the tangential tensile stresses are minimized and simultaneously the compressive tangential stresses are below the permissible limits. Though, pure theoretical analysis involving a trial process is available through the texts on structural optimization, the problem in case of tunnels has limitations. Here, selection has been made from few practically feasible shapes of the openings. This concept has been demonstrated in detail through nine different investigations for the case of a railway tunnel

Cardiac Response to β2 - A drenergic Stimulation is Attenuated in Old Rats Despite Higher Protein Expression

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No Sex Differences in Inflammatory Response and Vascular Function During Low Estrogen Phase

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Natural Fluctuations in Progesterone Do Not Impact Endothelial Function in Healthy Perimenopausal Women

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Effects of Melanin-Induced Free Radicals on the Isolated Rat Peritoneal Mast Cells

Pheomelanin from human red hair (RHM) produces considerably more cellular damage in Ehrlich ascites carcinoma cells when subjected to radiations of wavelength 320-700nm than eumelanin from black hair (BHM). Irradiation of RHM generated large amounts of superoxide while BHM did not produce detectable amounts of superoxide. The present investigations describe the effects of irradiation of mast cells in the presence of various natural and synthetic melanins. Irradiation of mast cells in the presence of RHM and red hair melanoprotein released large amounts of histamine while BHM and synthetic melanins prepared from dopa, cysteinyldopa, or a mixture of dopa and cysteinyldopa did not release histamine. The release of histamine at lower concentrations of RHM was not accompanied by the release of 51Cr from chromium-loaded cells, suggesting that this release was of noncytotoxic nature. On the other hand, the release of histamine at higher concentrations of RHM was due to cell lysis since both histamine and cytoplasmic marker 51Cr were released to the same extent. The release evoked by large concentration RHM was not inhibited by superoxide dismutase or catalase. This suggests that the cell lysis under these conditions was not due to H2O2 or O2-. The finding that mast cells release histamine when irradiated in the presence of RHM suggests that the immediate and late-phase reactions seen in sunburn may in part be due to the release of mediators from these cells