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This paper integrates competitive pricing and network design problems for the short life cycle products. The pricing problem determines selling prices of the products for different life cycle phases in a competitive market, as well as acquisition management of returned products. Besides, the selling and acquisition prices are related to the distance between distribution centers and customers. The network design problem aims to determine network flow and fleet assignment in each route. The proposed model is solved by various methods including exact and meta-heuristic approaches. The model and solving approaches have been validated and verified by several simulated examples and sensitivity analyses. Considering life cycle phases, competitive pricing, and transshipment problems as an integrated model, provides a new approach for the optimum solutions, which makes it more practical for application of real cases of short life cycle products. The results showed how the competition and fleet assignment influenced the optimum solution.

This paper integrates competitive pricing and network design problems for the short life cycle products. The pricing problem determines selling prices of the products for different life cycle phases in a competitive market, as well as acquisition management of returned products. Besides, the selling and acquisition prices are related to the distance between distribution centers and customers. The network design problem aims to determine network flow and fleet assignment in each route. The proposed model is solved by various methods including exact and meta-heuristic approaches. The model and solving approaches have been validated and verified by several simulated examples and sensitivity analyses. Considering life cycle phases, competitive pricing, and transshipment problems as an integrated model, provides a new approach for the optimum solutions, which makes it more practical for application of real cases of short life cycle products. The results showed how the competition and fleet assignment influenced the optimum solution.

CPC solar collectors are a combination of new technologies that make it possible to generate heat from radiant solar energy by transferring heat between the absorber and the fluid. This study was performed based on heat transfer equations by proposing a mathematical model, as reported in the literature. A compound parabolic concentrators solar collector (CPC) numerical model was simulated and coded in Aspen HYSYS and MATLAB software and validated by comparing its results with other researchers and experimental results. The simulated mathematical model includes a two-dimensional numerical model to describe the thermal and dynamic behavior of the fluid inside the CPC solar collector absorber tube. Numerical simulations of the fluid flow equations inside the CPC solar collector absorber tube, along with the energy equation for the absorber tube wall, coating, insulation and reflector, and solar collector heat analysis, were performed repeatedly in MATLAB and Aspen HYSYS software. This method is the most appropriate and reliable method for solving equations for numerical convergence. The experimental results of the parabolic concentrated solar collector (CPC) were used to evaluate and validate the numerical model. A solar compound parabolic concentrators collector (CPC) with short reflectors was used. This collector includes a cylindrical absorber with a real density ratio of 1.8, a reception angle of 22 degrees and a length of 2.81 m, a width of 0.32 m, and an opening of 0.1764 m. Analysis and uncertainty of the proposed model were performed with the measured sample. In the thermal efficiency analysis, the average deviation of the model from the experimental results of other researchers was equal to 7%, for increasing the temperature by 9 °C. According to these results, a good correlation between numerical results and experimental results for this proposed model has been obtained.

CPC solar collectors are a combination of new technologies that make it possible to generate heat from radiant solar energy by transferring heat between the absorber and the fluid. This study was performed based on heat transfer equations by proposing a mathematical model, as reported in the literature. A compound parabolic concentrators solar collector (CPC) numerical model was simulated and coded in Aspen HYSYS and MATLAB software and validated by comparing its results with other researchers and experimental results. The simulated mathematical model includes a two-dimensional numerical model to describe the thermal and dynamic behavior of the fluid inside the CPC solar collector absorber tube. Numerical simulations of the fluid flow equations inside the CPC solar collector absorber tube, along with the energy equation for the absorber tube wall, coating, insulation and reflector, and solar collector heat analysis, were performed repeatedly in MATLAB and Aspen HYSYS software. This method is the most appropriate and reliable method for solving equations for numerical convergence. The experimental results of the parabolic concentrated solar collector (CPC) were used to evaluate and validate the numerical model. A solar compound parabolic concentrators collector (CPC) with short reflectors was used. This collector includes a cylindrical absorber with a real density ratio of 1.8, a reception angle of 22 degrees and a length of 2.81 m, a width of 0.32 m, and an opening of 0.1764 m. Analysis and uncertainty of the proposed model were performed with the measured sample. In the thermal efficiency analysis, the average deviation of the model from the experimental results of other researchers was equal to 7%, for increasing the temperature by 9 °C. According to these results, a good correlation between numerical results and experimental results for this proposed model has been obtained.

Naphthenic acids are naturally occurring compounds that constitute part of the petroleum acids. They are corrosive species, and are toxic to a variety of organisms. Therefore, the removal of them is regarded as one of the most important issues. In this study, density functional theory approach has been devoted to investigate the adsorption of some naphthenic acids (e.g., benzoic acid, cyclohexan carboxylic acid, cyclohexan propionic acid) on magnesium oxide. The effect of aromaticity of the ring and the hydrocarbon chain of the naphthenic acids has been explored. Interaction energies, dipole moment, polarizability and energies of frontier orbitals have been calculated.

Naphthenic acids are naturally occurring compounds that constitute part of the petroleum acids. They are corrosive species, and are toxic to a variety of organisms. Therefore, the removal of them is regarded as one of the most important issues. In this study, density functional theory approach has been devoted to investigate the adsorption of some naphthenic acids (e.g., benzoic acid, cyclohexan carboxylic acid, cyclohexan propionic acid) on magnesium oxide. The effect of aromaticity of the ring and the hydrocarbon chain of the naphthenic acids has been explored. Interaction energies, dipole moment, polarizability and energies of frontier orbitals have been calculated.

This paper provides an overview of islanding fault detection in microgrids. Islanding fault is a condition in which the microgrid gets disconnected from the microgrid unintentionally due to any fault in the utility grid. This paper surveys the extensive literature concerning the development of islanding fault detection techniques which can be classified into remote and local techniques, where the local techniques can be further classified as passive, active, and hybrid. Various detection methods in each class are studied, and advantages and disadvantages of each method are discussed. A comprehensive list of references is used to conduct this survey, and opportunities and directions for future research are highlighted.

This paper provides an overview of islanding fault detection in microgrids. Islanding fault is a condition in which the microgrid gets disconnected from the microgrid unintentionally due to any fault in the utility grid. This paper surveys the extensive literature concerning the development of islanding fault detection techniques which can be classified into remote and local techniques, where the local techniques can be further classified as passive, active, and hybrid. Various detection methods in each class are studied, and advantages and disadvantages of each method are discussed. A comprehensive list of references is used to conduct this survey, and opportunities and directions for future research are highlighted.