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Design Configurations (design + configuration)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

Thermoeconomic optimization for a finned-tube evaporator configuration of a roof-top bus air-conditioning system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2008
M. Khamis Mansour
Abstract This paper presents a methodology of a design optimization technique that can be useful in assessing the best configuration of a finned-tube evaporator, using a thermoeconomic approach. The assessment has been carried out on a direct expansion finned-tube evaporator of a vapor compression cycle for a roof-top bus air-conditioning (AC) system at a specified cooling capacity. The methodology has been conducted by studying the effect of some operational and geometrical design parameters for the evaporator on the entire cycle exergy destruction or irreversibility, AC system coefficient of performance (COP), and total annual cost. The heat exchangers for the bus AC system are featured by a very compact frontal area due to the stringent space limitations and structure standard for the system installation. Therefore, the current study also takes in its account the effect of the variation of the design parameters on the evaporator frontal area. The irreversibility due to heat transfer across the stream-to-stream temperature difference and due to frictional pressure drops is calculated as a function of the design parameters. A cost function is introduced, defined as the sum of two contributions, the investment expense of the evaporator material and the system compressor, and the operational expense of AC system that is usually driven by an auxiliary engine or coupled with the main bus engine. The optimal trade-off between investment and operating cost is, therefore, investigated. A numerical example is discussed, in which a comparison between the commercial evaporator design and optimal design configuration has been presented in terms of the system COP and evaporator material cost. The results show that a significant improvement can be obtained for the optimal evaporator design compared with that of the commercial finned-tube evaporator that is designed based on the conventional values of the design parameters. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Random perturbation methods applied to multivariate spatial sampling design

ENVIRONMETRICS, Issue 7 2001
J. M. Angulo
Abstract The problem of estimating a multivariate spatial random process from observations obtained by sampling a related multivariate spatial random process is considered. A method based on additive perturbation of the variables of interest is proposed for the assignment of degrees of relative importance to the variables and/or locations of interest in the design of sampling strategies. In the case where the variables involved have a multivariate Gaussian distribution, some theoretical results are provided to justify the method proposed; in particular, it is proved that the amount of information contained in the data on the perturbed variables of interest is never higher than that contained in the original variables of interest. These results and the application of the method are illustrated with an empirical study, showing the variation of the effects of perturbation on spatial sampling design configurations and related ratios of information for different degrees of dependence according to the model specifications. Copyright © 2001 John Wiley & Sons, Ltd. [source]

An algorithm for fast optimal Latin hypercube design of experiments

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2010
Felipe A. C. Viana
Abstract This paper presents the translational propagation algorithm, a new method for obtaining optimal or near optimal Latin hypercube designs (LHDs) without using formal optimization. The procedure requires minimal computational effort with results virtually provided in real time. The algorithm exploits patterns of point locations for optimal LHDs based on the ,p criterion (a variation of the maximum distance criterion). Small building blocks, consisting of one or more points each, are used to recreate these patterns by simple translation in the hyperspace. Monte Carlo simulations were used to evaluate the performance of the new algorithm for different design configurations where both the dimensionality and the point density were studied. The proposed algorithm was also compared against three formal optimization approaches (namely random search, genetic algorithm, and enhanced stochastic evolutionary algorithm). It was found that (i) the distribution of the ,p values tends to lower values as the dimensionality is increased and (ii) the proposed translational propagation algorithm represents a computationally attractive strategy to obtain near optimum LHDs up to medium dimensions. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2010
Jit Ale
Abstract Purpose:, We employed an analytical approach to evaluate the key parameters for the potential design optimisation of accommodating intra-ocular lenses (AIOL) and to use these parameters to predict their accommodative performance. Methods:, Paraxial thin-lens equations to predict the accommodative performances of single-element (1E) and two-element (2E) AIOLs were developed. 2E-AIOLs with either mobile front or back lens elements were analysed as well as 1E-AIOL for their accommodative performance. A paraxial model including key ocular components (corneal surfaces, pupil and retina) as well as AIOL was used to evaluate the key control parameters and optimal design configurations. A range of variants of the model, representing varying powers of front and back optical elements and with either front or back optical element mobile was tested. Results:, Optimal accommodative performance of 2E-AIOL is governed by the power combinations of its optical elements; design variants with higher positive front element power produced greater accommodative efficacy, while mobility of the front element contributed more to the accommodative performance than the back element. The performance of 1E-AIOL is primarily governed by the power of the AIOL; the higher the AIOL power, the better the accommodative performance. Conclusions:, From an accommodative performance standpoint, the optimal design of 2E-AIOL should comprise a high plus power front element. Considering the maximum potential amounts of element translation available clinically, 2E-AIOLs are predicted to offer higher accommodative performance compared to 1E-AIOL. [source]