Salek F.,Technical and Vocational University |
Moghaddam A.N.,Technical and Vocational University |
Naserian M.M.,Technical and Vocational University
Energy Conversion and Management | Year: 2017
In this paper, Rankine cycle and Ammonia absorption cycle are coupled with Diesel engine to recover the energy of exhaust gases. The novelty of this paper is the use of ammonia absorption refrigeration cycle bottoming Rankine cycle which coupled with diesel engine to produce more power. Bottoming system converts engine exhaust thermal energy to cooling and mechanical energy. Energy transfer process has been done by two shell and tube heat exchangers. Simulation processes have been done by programming mathematic models of cycles in EES Program. Based on results, recovered energy varies with diesel engine load. For the particular load case of current research, the use of two heat exchangers causes 0.5% decrement of engine mechanical power. However, the recovered energy is about 10% of engine mechanical power. © 2017 Elsevier Ltd
Samim P.M.,Technical and Vocational University |
Fattah-Alhosseini A.,Bu - Ali Sina University
Analytical and Bioanalytical Electrochemistry | Year: 2016
In this work, the effect of cyclic potentiodynamic passivation (CPP) on the passive and electrochemical behavior of a mild carbon reinforcing steel in an alkaline media simulating the concrete pore (0.1 M NaOH+0.1 M KOH) solution was studied by electrochemical impedance spectroscopy (EIS) and Mott–Schottky analysis. Nyquist and Bode plots revealed that the passive film resistance of mild carbon reinforcing steel was increased by applying further CPP cycles. Mott–Schottky analysis showed that the passive films behave as both n-type and p-type semiconductors depending on the potential. Moreover, this analysis revealed that the semiconducting character of the passive films was not altered by CPP method. Also, it was found that both donor densities reduced by increasing the number of CPP cycles. More noble free potentials, smaller cyclic voltammogram loops, larger imperfect semicircles in the Nyquist plots, and less donor densities within the passive film were all indications of the positive effects of CPP. All electrochemical measurements revealed that the electrochemical behavior of mild carbon reinforcing steel was enhanced under the effect of CPP method, mainly attributed to the formation of thicker yet less defective passive films. © 2016 by CEE (Center of Excellence in Electrochemistry).
Rayeni M.M.,Technical and Vocational University |
Saljooghi F.H.,University of Sistan and Baluchestan
International Journal of Services and Operations Management | Year: 2014
This paper makes use of cross-efficiency measures, as an extension to data envelopment analysis (DEA). The cross-efficiency evaluation not only provides a ranking among the decision-making units (DMUs) but also eliminates unrealistic DEA weighting schemes without requiring a priori information on weight restrictions. A problem that possibly reduces the usefulness of the cross-efficiency evaluation method is that the cross-efficiency scores may not be unique due to the presence of alternate optima. So, it is recommended that secondary goals be introduced in cross-efficiency evaluation. In some cases, pursuing the best ranking is more important than maximising the individual score. This paper develops a new secondary goal based on symmetric weights selection. For illustration of models, the railway activities from 1977 to 2010 are considered and the efficiency of each year is calculated and compared to the other years. Copyright © 2014 Inderscience Enterprises Ltd.
Rayeni M.M.,Technical and Vocational University |
Saljooghi F.H.,University of Sistan and Baluchestan
International Journal of Services and Operations Management | Year: 2016
This paper investigates the impact of risk on banks performance. Banks, as a major source of financial intermediation and payment channel, play a vital role in the economic development of each country. The banking industry has been analysed through data envelopment analysis (DEA) by a number of researchers. DEA is a non-parametric method for relative evaluating the decision-making units (DMUs) with multiple inputs and outputs. In this study, due to the complexity and the subdivisions of the banks, the network DEA model was used. A three-stage model for evaluating the performance of bank branches was proposed and moreover, performance measurement and analysis was done through three models. In order to measure the effectiveness of risk in the first model, the risk-free efficiency was measured. Then, by adding risk to the model, risk-efficiency was obtained which considered as an undesirable indicator. In the third model, to consider the importance of risk, weight restriction was used in the model. The results of the three models show that the performance of the third model is much more desirable than the other models. Copyright © 2016 Inderscience Enterprises Ltd.
Jalilian J.,Islamic Azad University at Kermānshāh |
Motiepour P.,Technical and Vocational University
Journal of Magnetism and Magnetic Materials | Year: 2015
In a recent article by Ahmad et al. (2015)  structural, elastic, electronic, magnetic and optical properties of RbSrX (C, Si, Ge) half-Heusler compounds have been studied by the first principles calculations. After studying this article, we found that there are some physical and computational mistakes in electronic and optical properties sections. In investigating optical properties, they did not consider intraband transitions contribution in complex dielectric function term, while this term has significant effect on optical spectra for half-metallic materials. © 2015 Elsevier B.V.All rights reserved.
Modabbernia M.R.,Technical and Vocational University
International Journal on Electrical Engineering and Informatics | Year: 2013
In this paper a complete state-space average model for the buck switching regulators is presented. The presented model includes the most of the regulator's parameters and uncertainties. In modeling, the load current is assumed to be unknown, and it is assumed that the inductor, capacitor, diode and regulator active switch are non ideal and they have a resistance in conduction condition. Some other non ideal effects look like voltage drop of conduction mode of the diode and active switch are also considered. This model can be used to design a precise and robust controller that can satisfy stability and performance conditions of the buck regulator. Also the effects of the boost parameters on the performance of the regulator can be shown easily with this model. After presenting the complete model, the buck converter Benchmark circuit is simulated in PSpice and its results are compared with our model simulation results in MATLAB. The results show the merit of our model.
Arebi P.,Technical and Vocational University
Proceedings - 2012 4th International Conference on Computational Intelligence, Communication Systems and Networks, CICSyN 2012 | Year: 2012
Ad Hoc networks allow a set of wireless hosts to exchange information without any special infrastructure. One of the most important issues in wireless adhoc Network improves routing protocol process. Among the various factors which cause disorder in such a network and routing protocol process, broken links due to the lack of energy is the most important ones. This paper proposes a novel method based on energy estimation to restore broken links and reconstruct the paths of them. So investigate Effect of broken links on topology control and routing process in Ad Hoc network. It was indicated that these effects were harmful in the mentioned couple of network portions. In this paper has been used Hardware Method for estimation energy in adhoc node, so this method has a high speed. © 2012 IEEE.
Najafi A.,Technical and Vocational University
Advanced Studies in Theoretical Physics | Year: 2013
Here, a relatively good comparison has been done between the performance results of discontinuous and continuous forms of wave function on quantum systems as well. In this project, we've estimated the energy of ground and first state as the expectation value of Hamiltonian of harmonic oscillator and binding energy of nucleons confined in a Yukawa potential by making use of following three wave function: exponential, linear and Gaussian form which are convenient to optimize and may be evaluated rapidly are devised and tested and we stress the advantages of using expressions which are Gaussian in the variable parameters. Exponential function is quite different from a Gaussian ones as it has a cusp at x=0, hence a discontinuity in its derivatives. We then have performed to test inaccuracy of the discontinuous wave function and energy's error of its exact value because using of exponential and linear function by mathematical statements of calculation of delta and Heaviside function and either VMC calculation of wave function optimization, as both of them will have the same result of error value. The result of our study is very promising for future applications of quantum Monte Carlo methods especially in many body systems.
Razbani M.A.,Technical and Vocational University
Journal of Dispersion Science and Technology | Year: 2015
In this paper, a feed forward neural network is built and trained using experimental data reported in the literature to model interfacial tension of n-alkane/water-salt systems. Temperature, pressure, molecular weight of n-alkane, and ionic strength of electrolyte solution are used as input to the neural network. The model succeeded to predict interfacial tension of liquid n-alkane/water system with or without the presence of electrolyte and yielded average absolute deviation of 0.58% over all data points. The performance of the model is analyzed and compared against the performance of the other alternative models. It was found out that the proposed model outperforms the other alternatives. © 2015, Copyright © Taylor & Francis Group, LLC.
Zahedi E.,Technical and Vocational University
Life Science Journal | Year: 2012
Human development is the latest approach in developmental concept. Its objective is to "increase human choices" with the intention to improve living quality. This approach focuses on human and uses education as its main tool for human development. The idea is that a training individual acquires abilities and competences that turn that individual into an asset to be utilized for achievement of defined objectives. What is important in training programs is to indentifying specific qualities that may introduce individual and social changes to bring about improved quality of life. This article searches for training concepts that may promote educational, economic, social, and cultural equality.