A class of DCT approximations based on the Feig-Winograd algorithm

A tri-objective ant colony optimization based model for planning safe construction site layout

The field of goal programming is continuing to develop at a rapid pace. New variants of the goal programming model are being introduced into the literature and existing variants combined together to form a more comprehensive and flexible modelling structure. Goal programming is also being applied to wide a range of modern applications and is increasingly being used in combination with other techniques from operations research and artificial intelligence to enhance its modelling flexibility. This paper presents a review of the field of goal programming focussing on recent developments. The current range of goal programming variants is described. The range of techniques that goal programming has been combined or integrated with is discussed. A range of modern applications of goal programming are given and conclusions are drawn.

A Review of Goal Programming

Surface quality of the machined parts is one of the most important product quality indicators and one of the most frequent customer requirements. The average surface roughness (Ra) represents a measure of the surface quality, and it is mostly influenced by the following cutting parameters: the cutting speed, the feed rate, and the depth of cut. Quantifying the relationship between surface roughness and cutting parameters is a very important task. In this study regression analysis was used for modelling and optimization of the surface roughness in dry single-point turning of the alloyed steel, using coated tungsten carbide inserts. The experiment has been designed and carried out on the basis of a three-level full factorial design. The linear, the quadratic and the power (non-linear) mathematical models were selected for the analysis. Obtained results are in good accordance with the experimentally obtained data, confirming the effectiveness of regression analysis in modelling and optimization of surface roughness in the turning process. The general conclusion is that the surface roughness has a clear downward trend with the cutting speed increase and decrease in the feed rate and the depth of cut.

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Modelling and optimization of the surface roughness in the dry turning of the cold rolled alloyed steel using regression analysis

Improving the discharge process of phase change materials (PCMs) is of great importance and can be effective for thermal energy storage (TES) systems. In this research, the direct-contact method for acetone droplet on molten paraffin is optimized to enhance the efficiency of the discharge process of PCMs and TES systems working with intermediate boiling fluid (IBF). In order to improve the storage rate and increase the freezing rate in the system, the NSGA-II algorithm is used. When the acetone droplet hits, owing to its low boiling point relative to the temperature of molten paraffin, the acetone evaporates, causing the creation of solidified paraffin area. The main goal of the current investigation is to maximize the solid volume, which depends on two parameters: the Weber acetone droplet and the temperature of the molten paraffin. Furthermore, maximizing this volume is equivalent to increasing the freezing rate and decreasing the melting rate. For better discernibility, the relative sensitivities of solidified paraffin area and maximum crater depth to the variations in the dimensionless parameters of paraffin surface temperature and Weber number are obtained. In this regard, the experimental results are fitted by exponential functions. Two-objective optimization with the solidified paraffin area and maximum crater depth as cost functions are performed to be maximized. Moreover, uncertainties and tolerances are considered through performing a robust triple optimization. By using final decision makings (FDMs), the results are achieved from Pareto front through two methods, LINMAP (We = 1699.428, θ = 1.188) and TOPSIS (We = 1699.325, θ = 1.202). Based on the results, the solidified paraffin areas obtained by LINMAP and TOPSIS methods are 168.616 mm2 and 155.101 mm2, respectively. 

Multi-objective optimization of acetone droplet impingement on phase change material in direct-contact discharge method

Optimization problems often involve situations in which the user's goal is to minimize and/or maximize not a single objective function, but several, usually conflicting, functions simultaneously. Such situations are formulated as multiobjective optimization problems, also known as multicriteria, multiperformance or vector optimizations. Because multiobjective optimization problems arise in different scientific applications, many researches have focused on developing methods for their solution. Thus, there are several criteria that can be considered to solve such complex optimizations. This paper contributes to the study of optimization problems, by comparing some of these methods. The classical method, based on function scalarization, in which a vector function is transformed into a scalar function, is represented here by the weighted objectives and global criterion methods. A different approach involves hierarchical, trade-off and goal programming, which treats the objective functions as additional constraints. Some multicriteria optimization problems are given to illustrate each methodology studied here. The techniques are initially applied to an environmentally friendly and economically feasible electric power distribution problem. The second application involves a dynamics optimization problem aimed at optimizing the first three natural frequencies.

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Multiobjective optimization techniques applied to engineering problems

The aim of the present work is to investigate the burr formation mechanisms at the edges (lateral and exit) during face milling of mould steel using carbide tools. The effects of the cutting parameters were studied and strategies of burr minimization were discussed. The proposed minimization was achieved by optimizing the cutting conditions: cutting speed (Vc), feed per tooth (fz) and depth of cut (doc), with the aid of surface response technique.

/pdf/optimization-of-the-cutting-conditions-vc-fz-and-doc-for-2w1hd9v8pc.pdf

Optimization of the cutting conditions (Vc, fz and doc) for burr minimization in face milling of mould steel

Optimization problems often involve situations in which the user’s goal is to minimize and/or maximize not a single objective function, but several, usually conflicting, functions simultaneously. Such situations are formulated as multiobjective optimization problems, also known as multicriteria, multiperformance or vector optimizations. Because multiobjective optimization problems arise in different scientific applications, many researches have focused on developing methods for their solution. Thus, there are several criteria that can be considered to solve such complex optimizations. This paper contributes to the study of optimization problems, by comparing some of these methods. The classical method, based on function scalarization, in which a vector function is transformed into a scalar function, is represented here by and global criterion the weighted objectivesmethods. A different approach involves hierarchical, trade-off and goal programming, which treats the objective functions as additional constraints. Some multicriteria optimization problems are given to illustrate each methodology studied here. The techniques are initially applied to an environmentally friendly and economically feasible electric power distribution problem. The second application involves a dynamics optimization problem aimed at optimizing the first three natural frequencies.

/pdf/multiobjective-optimization-techniques-applied-to-2tq7z7s6e9.pdf

Sezimária F. P. Saramago

Papers

Multiobjective optimization techniques applied to engineering problems

Optimization of the cutting conditions (Vc, fz and doc) for burr minimization in face milling of mould steel

Multiobjective Optimization Techniques Applied to Engineering