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排序方式: 共有1210条查询结果,搜索用时 15 毫秒
91.
Shah M. Yunus Sunil Saigal Robert D. Cook 《International journal for numerical methods in engineering》1989,28(4):785-800
A set of three new hybrid elements with rotational degrees-of-freedom (d.o.f.'s) is introduced. The solid, 8-node, hexahedron element is developed for solving three-dimensional elasticity problems. This element has three translational and three rotational d.o.f.'s at each node and is based on a 42-parameter. three-dimensional stress field in the natural convected co-ordinate system. For two-dimensional, plane elasticity problems, an improved triangular hybrid element and a quadrilateral hybrid element are presented. These elements use two translational and one rotational d.o.f. at each node. Three different sets of five-parameter stress fields defined in a natural convected co-ordinate system for the entire element are used for the mixed triangular element. The mixed quadrilateral element is based on a nine-parameter complete linear stress field in natural space. The midside translational d.o.f.'s are expressed in terms of the corner nodal translations and rotations using appropriate transformations. The stiffness matrix is derived based on the Hellinger–Reissner variational principle. The elements pass the patch test and demonstrate an improved performance over the existing elements for prescribed test examples. 相似文献
92.
The combined effect of magnetic field and rotation on thermosolutal instability of a compressible fluid in porous medium is considered. The system is found to be stable for (Cp/g)β < 1 where Cp, β, and g stand for specific heat at constant pressure, uniform adverse temperature gradient, and acceleration due to gravity, respectively. The stable solute gradient, magnetic field, and rotation introduce oscillatory modes in the system for (Cp/g)β > 1, which were nonexistent in their absence. For stationary convection, the stable solute gradient and rotation have a stabilizing effect on the system for (Cp/g)β > 1. In the presence of rotation, the magnetic field has a stabilizing (or destabilizing) effect, and the medium permeability has a destabilizing (or stabilizing) effect under certain condition, whereas in the absence of rotation, the magnetic field and rotation have stabilizing and destabilizing effects for (Cp/g)β > 1, respectively, on the system. The sufficient conditions for the existence of overs-lability are obtained. 相似文献
93.
Kesavan Sunil K. Reddy Narender P. Yazdani-Ardakani Saeed 《IEEE transactions on bio-medical engineering》1986,(9):898-900
Water irrigation devices (WID's) are widely used in homes and dental clinics across the country for oral hygiene. There have been several reported cases of tissue damage with the use of these devices. In the present investigation, two commercially available oral water irrigation devices were evaluated using engineering techniques. The impact thrusts delivered by these devices were measured at different control settings. Both of the tested commercial oral water irrigation devices were found to exert abnormally high thrust which could cause serious damage to the sulcular epithelium and the underlying tissues. These pressures are far in excess of the pressure intensity necessary to perform the cleaning action. Moreover, the existing designs using reciprocating pumps are unsafe and are potentially dangerous, particularly with small diameter tips. 相似文献
94.
Murat Manguoglu Ahmed H. Sameh Tayfun E. Tezduyar Sunil Sathe 《Computational Mechanics》2008,43(1):73-80
We present an effective preconditioning technique for solving the nonsymmetric linear systems encountered in computation of
incompressible flows in long domains. The application category we focus on is arterial fluid mechanics. These linear systems
are solved using a nested iterative scheme with an outer Richardson scheme and an inner iteration that is handled via a Krylov
subspace method. Test computations that demonstrate the robustness of our nested scheme are presented. 相似文献
95.
In this article we propose a multiple-output parity bit signature generation method for exhaustive testing of VLSI circuits. Given a multiple-output combinational circuit, a parity bit signature is generated by first EXORing all the outputs to produce a new output function and then feeding this resulting function to a single-output parity bit signature generator. The method preserves all the desirable properties of the conventional single-output circuits response analyzers and can be readily implemented using the current VLSI technology. 相似文献
96.
The loss of zero-voltage-switching (ZVS) of active switches has been a serious limitation of full-bridge (FBZVS) converters.
Many techniques have been proposed in the past to extend the range of ZVS operation over the wider and also the full range
of operation. However, in these techniques ZVS is achieved at the expense of additional conduction loss in active switches
and losses in the auxiliary components. In this paper, the analysis for the additional losses in various full-range FBZVS
DC-DC converters and their comparative evaluation is reported. Closed form expressions are derived for average value of device
currents and losses. The loss curves for various topologies are plotted and compared. The analytical results are found to
be consistent with the experimental efficiency tests performed on 500 W, 100 kHz prototype. It is concluded that a recently
proposed new topology has the least penalty of additional losses. 相似文献
97.
Harinder Singh Oberoi Sunil Bansal & Gurpreet Singh Dhillon 《International Journal of Food Science & Technology》2008,43(8):1499-1504
Among the five Kluyveromyces marxianus strains tested for β-galactosidase production, K. marxianus NCIM 3465 showed maximum enzyme activity of 1.62 IU mg−1 dry weight. Different levels (5–25%, w/v) of dried cauliflower waste were incorporated into whey to evaluate the effect of its supplementation on enzyme production. Although a marginal increase in enzyme production was seen by incorporating 5% and 10% cauliflower waste in whey, nearly 15% increase in β-galactosidase production was observed when cauliflower waste level was increased to 20% compared with whey alone. Supplementing whey with 20% cauliflower waste also decreased the production time. Lactose concentration in whey, mainly responsible for increasing the biological oxygen demand load of the effluent water, decreased from 4.2% to nearly 0% at 24 h. Thus, this study demonstrated that both these by-products/residues could be effectively used for β-galactosidase production at commercial scale. 相似文献
98.
Niranjan Mahendra Singh Jha Sunil 《The International Journal of Advanced Manufacturing Technology》2015,80(9-12):1895-1902
The International Journal of Advanced Manufacturing Technology - Magnetorheological (MR) finishing is a smart finishing processes applied to a variety of applications. In the present work, an... 相似文献
99.
The dry hot syngas cleaning process appears to be potentially more efficient and cleaner than the proven wet cleaning or semi-wet cleaning processes but it is still far from commercialisation. There are several technological barriers responsible such as poor availability factor, degeneration of sorbent and several stages of separation. This paper summarises the reported current status of dry hot cleaning of syngas from coal gasification processes along with the shortcomings of reporting of dry hot syngas cleaning performance results. The paper also proposes and discusses a rational method of performance reporting, a novel pulse less filtration concept and a system to prevent failure of filter elements. 相似文献
100.
CO2 flooding, which is an efficient method of enhanced oil recovery, is a very complicated process involving phase behavior. To understand the performance of CO2 flooding and provide accurate data for designing reservoir development, a comprehensive investigation of the phase behavior of CO2 miscible flooding and an accurate compositional reservoir simulation needs to be conducted. In PVT modeling, an effective and more physically reasonable equation of state model was achieved and the feasibility of CO2 miscible flooding was determined by multiple contact minimum miscibility pressure (MCMMP) calculation. Furthermore, compositional reservoir simulation studies for predicting CO2 miscible performance were designed and constructed with core flooding data. By matching with laboratory core flooding data, we can estimate parameters with uncertainty. The objective of this study was to find a work flow for parameter estimation in CO2 miscible flooding process that can be used to design and optimize field CO2 miscible floods. 相似文献