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91.
Analysis of steady-state characteristics of misaligned hydrodynamic journal bearings with isotropic roughness effect 总被引:1,自引:0,他引:1
S. K. Guha 《Tribology International》2000,33(1):1
The present work deals with the concept of a stochastic process to solve the problem of isotropic steady-state characteristics of hydrodynamic journal bearings of finite width, considering two types of misalignment, axial (vertical displacement) and twisting (horizontal displacement). Using a finite-difference method, the steady-state film pressures are obtained by solving a Reynolds type equation based on the principle of isotropic roughness pattern. With the help of the steady-state film pressures, the steady-state performance characteristics, in terms of load-carrying capacity, attitude angle, leakage flow-rate, friction coefficient and misalignment moment of a journal bearing with the slenderness ratio of unity, are obtained for various values of isotropic roughness parameter, eccentricity ratio and degree of misalignment. 相似文献
92.
Savas Delikanli Guannan Yu Aydan Yeltik Sumanta Bose Talha Erdem Junhong Yu Onur Erdem Manoj Sharma Vijay Kumar Sharma Ulviyya Quliyeva Sushant Shendre Cuong Dang Dao Hua Zhang Tze Chien Sum Weijun Fan Hilmi Volkan Demir 《Advanced functional materials》2019,29(35)
Surface effects in atomically flat colloidal CdSe nanoplatelets (NLPs) are significantly and increasingly important with their thickness being reduced to subnanometer level, generating strong surface related deep trap photoluminescence emission alongside the bandedge emission. Herein, colloidal synthesis of highly luminescent two‐monolayer (2ML) CdSe NPLs and a systematic investigation of carrier dynamics in these NPLs exhibiting broad photoluminescence emission covering the visible region with quantum yields reaching 90% in solution and 85% in a polymer matrix is shown. The astonishingly efficient Stokes‐shifted broadband photoluminescence (PL) emission with a lifetime of ≈100 ns and the extremely short PL lifetime of around 0.16 ns at the bandedge signify the participation of radiative midgap surface centers in the recombination process associated with the underpassivated Se sites. Also, a proof‐of‐concept hybrid LED employing 2ML CdSe NPLs is developed as color converters, which exhibits luminous efficacy reaching 300 lm Wopt?1. The intrinsic absorption of the 2ML CdSe NPLs (≈2.15 × 106 cm?1) reported in this study is significantly larger than that of CdSe quantum dots (≈2.8 × 105 cm?1) at their first exciton signifying the presence of giant oscillator strength and hence making them favorable candidates for next‐generation light‐emitting and light‐harvesting applications. 相似文献
93.
In this paper we give efficient parallel algorithms for solving a number of visibility and shortest-path problems for simple polygons. Our algorithms all run inO(logn) time and are based on the use of a new data structure for implicitly representing all shortest paths in a simple polygonP, which we call thestratified decomposition tree. We use this approach to derive efficient parallel methods for computing the visibility ofP from an edge, constructing the visibility graph of the vertices ofP (using an output-sensitive number of processors), constructing the shortest-path tree from a vertex ofP, and determining all-farthest neighbors for the vertices inP. The computational model we use is the CREW PRAM. 相似文献
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We consider the following four problems for a setS ofk points on a plane, equipped with the rectilinear metric and containing a setR ofn disjoint rectangular obstacles (so that distance is measured by a shortest rectilinear path avoiding obstacles inR): (a) find aclosest pair of points inS, (b) find anearest neighbor for each point inS, (c) compute the rectilinearVoronoi diagram ofS, and (d) compute a rectilinearminimal spanning tree ofS. We describeO ((n+k) log(n+k))-time sequential algorithms for (a) and (b) based onplane-sweep, and the consideration of geometrically special types of shortest paths, so-calledz-first paths. For (c) we present anO ((n+k) log(n+k) logn)-time sequential algorithm that implements a sophisticateddivide-and-conquer scheme with an addedextension phase. In the extension phase of this scheme we introduce novel geometric structures, in particular so-calledz-diagrams, and techniques associated with the Voronoi diagram. Problem (d) can be reduced to (c) and solved inO ((n+k) log(n+k) logn) time as well. All our algorithms arenear-optimal, as well as easy to implement.
An extended abstract appeared inProc. 13th Conf. on the Foundations of Software Technology and Theoretical Computer Science, Bombay, 1993, Springer-Verlag, pp. 218–227. Sumanta Guha was supported in part by a UW-Milwaukee Graduate School Research
Committee Award. Ichiro Suzuki was supported in part by the National Science Foundation under Grants CCR-9004346 and IRI-9307506,
the Office of Naval Research under Grant N00014-94-1-0284, and an endowed chair supported by Hitachi Ltd. at the Faculty of
Engineering Science, Osaka University. 相似文献
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In the synthesis of the superconducting compound Ba2 YCu3 O7-x from a stoichiometric mixture containing BaCO3 , Y2 O3 , and CuO In air, a low-melting liquid phase is formed at about 890°C. The liquid phase was identified as a ternary eutectic located within the compatibility triangle Ba2 YCu3 O7-x –BaCuO2 –CuO. The implication of this finding for the processing of Ba2 YCu3 O7-x is discussed. 相似文献
100.
V. Koul S. Ansari K. Sharma S. Anand S. K. Guha 《Journal of materials science. Materials in medicine》1995,6(4):192-196
Alteration in motility and vitality of human spermatozoa treated with various polymeric hydrogels in vitro has been studied. Different copolymers of acrylic acid-co-methylmethacrylate, poly (AA-co-MMA); acrylic acid-co-butylacrylate, poly (AA-co-BA); Itaconic acid-co-methylmethacrylate, poly (IA-co-MMA); styrene maleic anhydride, poly (SMA) and homo-polymers of polyacrylic acid, poly (AA); poly methylmethacrylate, poly (MMA) were taken. Of all the polymers studied, the following three groups of water-insoluble polymers, namely poly(IA-co-MMA), poly(AA-co-MMA) and poly (AA-co-BA) proved to be strong inhibitors of spermatozoa motility and vitality. The homopolymer of acrylic acid which is water soluble, also exhibited strong inhibitory action. Poly (MMA) did not show any such effects. 相似文献