ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677805

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An incompressible Reynolds‐averaged Navier‐Stokes (RANS) computational procedure is presented. Numerical computations using a three‐dimensional computer code with multigrid capability are made on two axisymmetric bodies at a Reynolds number (about 107) to investigate the effects of grid distribution and turbulence modeling on computed stern flows. Numerical‐experimental comparisons are presented for pressure and skin friction coefficients on the body, and axial velocity and turbulent shear stress profiles at two locations in the stern region. The root‐mean‐square (RMS) differences of the measured and computed flow variables are summarized. A grid‐independent numerical solution has been obtained from the present RANS computer code when the average value of y+1for the first grid center from the wall, has been less then 7, and the rate of covergence has been monitored to avoid the use of grid cells with excessively large aspect ratios. Two modifications of the Baldwin‐Lomax turbulence model have been shown to improve the predictions.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677806

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A viscoelastic four‐tube arteries—micro‐vessels—veins model has been built using transmission line network. Hemodynamic data from literature are used in the fluid‐circuit analogic model. The predicted input impedance spectra agree reasonably well with the published measurements. Parametric analysis shows that the changes in the vascular properties in different portions of the body cause fluctuations of the maxima or minima of the impedance spectrum. In general, the changes of vascular properties in the lower body affect the first minimum, and the changes in the upper body influence the second minimum. Decreasing capacitances (i.e., increasing arterial stiffness due to aging), reducing the lumen area, or decreasing the length of blood vessels result in an increase of the impedance modulus, and the shift of the first minimum to a higher frequency, which agree well with experiments. The changes of peripheral resistances of all terminations affect the magnitude of impedance modulus maxima only. The current model uses simple physiological data directly; it can be used to simulate the effect of pharmacologic manipulation on the impedace spectra of the patients.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677807

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The Random filter is a well‐known search filter proposed by Wang et al. The authors of the same paper have compared the Random filter with the Bloom filter, proposed by Bloom. Wang et al. have proved the superiority of the Random filter over the Bloom filter in false drop probability and average testing time. In this article, we shall demonstrate that under some reasonable conditions, the performance of the Random filter is not better than Bloom's by mathematical analysis and numerical comparison.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677808

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The technique of the supported‐liquid membrane (SLM) has been employed to remove phenol from aqueous streams. The sulfuric acid salts of trioctylamine (TOA salts), which have been produced from the reaction of trioctylamine (TOA) and sulfuric acid, dissolved in TOA, have been used as the carrier material which filled in the pore of the membrane. 1‐octanol has been added to the organic solution to make it a homogeneous organic solution. The transport of phenol is expressed by the permeability of the phenol which is an index to indicate the extraction capability of phenol through the supported‐liquid membrane. VVLP, GVHP and PP membranes have been employed to examine the characteristics of extraction. Effects of the operating conditions and parameters, such as the initial concentration of phenol in the aqueous phase, the initial concentration of sulfuric acid in the feed solution, the initial concentration of sodium hydroxide in the stripping solution and the initial concentration of TOA salts in the VVLP membrane on the permeability were investigated in detail.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677809

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The component method is proposed to study the free vibration of a multispan Mindlin plate. The orthogonality of any two distinct sets of the mode shape functions is shown. A method of modal analysis is then presented to study the dynamic responses of the plates. A line load moving on the plate is used as an example. The effects of span number, rotatory intertia and transverse shear deformation on the critical velocity, the maximum displacement and the maximum moment of plates are discussed. Furthermore, the effect of the thickness‐length ratio on the critical velocity is also investigated. The results of a Mindlin plate are compared with those of a classical plate.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677810

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Corrosion behaviours of carbon steel coated with polyester and polyvinylester in a simulated flue gas desulphurisation (FGD) fluid (i.e., a mixture of H2SO4and 0.1 wt% Fe2(SO4)3at pH=2) have been investigated with electrochemical impedance spectroscopy (EIS). The protective nature of the coatings at 25°C has been observed in the following order: polyvinylester primer >> polyvinylester topcoat > polyester topcoat > polyester primer. Coating deterioration occurred and the coating deterioration rate accelerated with increasing temperatures upto 85°C. However, the corrosion resistance sequence has remained the same. Equivalent circuits are suggested for various coatings to discuss their mechanisms in this work.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677811

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Distribution networks contain a large number of components and, in many cases, the required data for network modeling are often missing or uncertain. In order to circumvent the problem of dealing with uncertain data, uncertainties in network parameters and feeder node injections are handled by using the “unknown but bounded” scheme. A possibility approach used to take into account the effects of uncertainties in distribution system state estimation is proposed in this paper. In the proposed estimation approach, all possible solutions within bounds are considered. Test results have shown that this approach can handle various uncertainties that exist in the network model and the solutions obtained can provide useful information for distribution system operations.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677812

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Usually, a single optimization criterion for redundancy resolution of redundant manipulators is used in the literature. However, in many cases, a single optimization criterion is not sufficient to deal with complicated task environments. Hence, taking multiple goals into consideration simultaneously is a new research area for redundant manipulators. In this paper, with the Compact QP (quadratic programming) formulation, a systematic algorithm using Parallel Scheme and Pre‐adjustment (PSP) will be developed for resolving the multiple‐goal problem. In this approach, first, the decision making strategies are proposed for the multiple‐goal considerations. With the decision making strategies, the Parallel Scheme is developed for weighting adjustment. Also, a Pre‐adjustment is proposed to generate proper weighting factors for the next sampling interval. Two examples are used to demonstrate the superiority and universality of this systematic algorithm. From the simulation results, it is believed that the PSP systematic algorithm together with the Compact QP method provide a general and effective approach to resolve the multiple‐goal problem of redundant manipulators.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677813

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This article analyzes different operation strategies in project management from an economic viewpoint and proposes a general procedure to schedule a project when inflation is either considered, with linear or ladder type, or not considered.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677814

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor