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A molecular dynamics study: Structures and thermal stability of PdmPt(13-m)Ag42 ternary nanoalloys

Garip, Ali Kemal

Article | 2018 | INTERNATIONAL JOURNAL OF MODERN PHYSICS C29 ( 9 )

Structural optimization of ternary PdmPt(13-m)Ag42 nanoalloys was performed using the basin-hopping algorithm, and the Gupta many-body potential was adopted to model interatomic interaction. The optimization results show that all compositions have a structure based on icosahedron with a coreshell segregation. While the Ag atoms prefer to segregate to the surface, Pd and Pt atoms were located at the core of the cluster due to the higher surface and cohesive energy. The single platinum atom with the highest cohesive energy in Pd12Pt1Ag42 nanoalloy was located at the center of the cluster. Also in all other compositions except Pd13Ag42 . . ., Pd atoms occupy the second shell position of the icosahedron structure. We used classical molecular dynamics (MD) simulations in canonical ensemble conditions (NVT) to investigate the melting temperatures of ternary PdmPt(13-m)Ag42 nanoalloys with the interatomic interactions modeled by the same potential with optimizations. The icosahedral structures were taken as the initial configurations for MD simulations. We obtained caloric curves and Lindemann indexes to investigate the melting transitions. The simulation results showed that varying the composition gives rise to a fluctuation in melting temperatures. The highest melting temperature belongs to the Pd9Pt4Ag42 nanoalloy cluster within the other compositions. However, the relative stability investigation indicates the Pd8Pt5Ag42 nanoalloy cluster as the most stable composition. The Lindemann indexes obtained for the second and third shell of icosahedral structures show that the melting takes place as a whole without any surface premelting Daha fazlası Daha az

Shell-and-tube heat exchangers optimization according to design and cost parameters [Gövde-boru tipi isi degiştirgeçlerinin tasarim ve maliyet parametrelerine göre optimizasyonu]

Engin T. | Güngör K.E.

Article | 1996 | Turkish Journal of Engineering and Environmental Sciences20 ( 6 ) , pp.313 - 322

The most economical design of heat exchangers, depends upon an optimum balance between the heat transfer area and the energy consumption arising because from the pressure loss of streams on both sides of the exchanger. Heat exchanger optimization is, therefore, a complex and iterative engineering problem due to too many parameters affecting the design. Such an optimization process is basically based on the determination of the optimum pressure losses. In this study, optimum design of the heat exchangers commonly used in industry is investigated. The optimization method being used, consists of the minimization of the total cost funct . . .ion including heat exchanger capital and energy consumption costs of the system. This study does not cover heat exchanger types such as condenser and evaporator, in which streams undergo phase changes along the process. Nevertheless, the use of this method is highly practical for all of the heat exchanger types in which the heat transfer takes place from liquid to liquid, from liquid to gas and from gas to gas. In this paper, the fundamentals of the method are given first, then, the application to the Shell-and-Tube Heat Exchangers is introduced. But being able to size a heat exchanger, optimally, by using this method depends on determining, objectively, the cost functions which are being taken as basis. Hence, the reliability of this method, on the cost basis, is restricted by the consistency of expressions of the real cost values in the cost functions of the heat exchanger and those of the flow machines Daha fazlası Daha az

Optimization of wavelet based OFDM for multipath powerline channel by genetic algorithm

Kumbasar V. | Kucur O. | Ergin A.A. | Öztürk E.

Article | 2009 | Wireless Communications and Mobile Computing9 ( 9 ) , pp.1243 - 1250

Using genetic algorithm (GA), optimal wavelets are obtained to reduce ISI and ICI powers of a wavelet-based orthogonal frequency division multiplexing (OFDM) system over a practical two path low-voltage powerline channel or two path fading channel by relaxing the perfect quadrate mirror filter (QMF) orthogonality. Optimum wavelet-based OFDM system experiences less interference compared to conventional and Daubechies (Db) wavelet-based OFDM systems. © 2008 John Wiley & Sons, Ltd.

Comparing of phase shifting method and one-dimensional continuous wavelet transform method for reconstruction using phase-only information

Ustabaşkaya G. | Saraç Z.

Article | 2017 | Turkish Journal of Electrical Engineering and Computer Sciences25 ( 2 ) , pp.1587 - 1597

The one-dimensional continuous wavelet transform method has some advantages in hologram reconstruction, when used in the only phase, compared with the phase shifting method. This paper aims to discuss these advantages. One advantage is related to image quality. Another advantage is less power spent and saving time, because the one-dimensional continuous wavelet transform method uses only one hologram and the phase shifting method uses four holograms for recording and reconstruction processes. One final advantage is that the one-dimensional continuous wavelet transform method can also be used in real-time applications. Within the con . . .text of the ongoing optimization studies, this study will make a significant contribution to the literature because of these mentioned advantages. © TÜBİTAK Daha fazlası Daha az

A molecular dynamics study: Structures and thermal stability of Pd m Pt(13-m) Ag42 ternary nanoalloys

Garip A.K.

Article | 2018 | International Journal of Modern Physics C29 ( 9 ) , pp.1587 - 1597

Structural optimization of ternary PdmPt(13-m)Ag42 nanoalloys was performed using the basin-hopping algorithm, and the Gupta many-body potential was adopted to model interatomic interaction. The optimization results show that all compositions have a structure based on icosahedron with a core-shell segregation. While the Ag atoms prefer to segregate to the surface, Pd and Pt atoms were located at the core of the cluster due to the higher surface and cohesive energy. The single platinum atom with the highest cohesive energy in Pd12Pt1Ag42 nanoalloy was located at the center of the cluster. Also in all other compositions except Pd13Ag4 . . .2, Pd atoms occupy the second shell position of the icosahedron structure. We used classical molecular dynamics (MD) simulations in canonical ensemble conditions (NVT) to investigate the melting temperatures of ternary PdmPt(13-m)Ag42 nanoalloys with the interatomic interactions modeled by the same potential with optimizations. The icosahedral structures were taken as the initial configurations for MD simulations. We obtained caloric curves and Lindemann indexes to investigate the melting transitions. The simulation results showed that varying the composition gives rise to a fluctuation in melting temperatures. The highest melting temperature belongs to the Pd9Pt4Ag42 nanoalloy cluster within the other compositions. However, the relative stability investigation indicates the Pd8Pt5Ag42 nanoalloy cluster as the most stable composition. The Lindemann indexes obtained for the second and third shell of icosahedral structures show that the melting takes place as a whole without any surface premelting. © 2018 World Scientific Publishing Company Daha fazlası Daha az

Optimization of digital holographic setup by a fuzzy logic prediction system

Kaya, Gülhan Ustabaş | Erkaymaz, Okan | Saraç, Zehra

Article | 2016 | Expert Systems with Applications56 , pp.177 - 185

In this study, the optimization of the digital holography setup is achieved by a using fuzzy logic prediction system. In fact, when this optimization process is experimentally performed, some parameters are changed in the setup. These parameters affect directly the obtained image quality after a reconstruction process, which is determined by normalized root mean square. The aim of this study is to achieve the optimization of digital holographic setup by using both experimental and fuzzy logic prediction systems. Furthermore, the required time during the experimental optimization can be lowered by using a numerical method like the fu . . .zzy logic prediction system. Here, the experimental optimization results and the optimization results obtained by the fuzzy logic prediction system are compared. It is offered that the designed experimental system can be optimized by using an artificial intelligent tool. The applied fuzzy logic prediction model is used the first time for optimization of hologram recording setup. As a result, it is reached a conclusion that the optimization of digital holographic setup can be numerically performed by the fuzzy logic prediction system. Moreover, while digital holographic setup is experimentally designed, the required time for optimization is reduced, as well. © 2016 Elsevier Ltd. All rights reserved Daha fazlası Daha az

A new adaptive neuro-fuzzy solution for optimization of the parameters in the digital holography setup

Ustabaş, Kaya Gülhan | Erkaymaz, Okan | Saraç, Zehra

Article | 2019 | Soft Computing23 ( 18 ) , pp.8827 - 8837

In this paper,a fuzzy interference and an adaptive neuro-fuzzy interference system models have been presented in order to accelerate designing of the digital holographic setup without experiment. The setting parameters of experimental holographic setup, which affect the quality of images obtained from reconstructed holograms, are predicted digitally by proposed models before the recording process. Hence, we reduce the required time for designing of digital holographic setup with optimization process. The adaptive neuro-fuzzy interference system model for the optimization of the digital holographic setup is first attempt in the liter . . .ature. The accuracy of the proposed models is examined by comparing the presented models and actual calculated experimental root-mean-square values. As a result, the accuracy of the adaptive neuro-fuzzy interference system shows the better performance than the fuzzy interference system. Moreover, the design of experimental setup can be occurred numerically in a short time by using adaptive neuro-fuzzy interference system models. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature Daha fazlası Daha az

Optimization of arsenic removal from drinking water by electrocoagulation batch process using response surface methodology

Kobya, Mehmet | Demirbaş, Erhan | Geboloğlu, Uğur | Öncel, Mehmet Salim | Yıldırım, Yılmaz

Article | 2013 | Desalination and Water Treatment51 ( 34-36 ) , pp.6676 - 6687

In this investigation, arsenic removal from drinking water using electrocoagulation (EC) in a batch mode was studied by response surface methodology (RSM). The RSM was applied to optimize the operating variables viz. current density (CD, A/m2), operating time (tEC, min) and arsenic concentration (Co, µg/L) on arsenic removal in the EC process using iron electrodes. The combined effects of these variables were analyzed by the RSM using quadratic model for predicting the highest removal efficiency of arsenic from drinking water. The proposed model fitted very well with the experimental data. R2 adjusted correlation coefficients (AdjR2 . . .: 0.93) for arsenic removal efficiency showed a high significance of the model. The model predicted for a maximum removal of arsenic at the optimum operating conditions (112.3 µg/L, 5.64 A/m2 and 5 min) after the EC process was 93.86% which corresponded to effluent arsenic concentration of 6.9 µg/L. The minimum operating cost (OC) of the EC process was 0.0664 €/m3. This study clearly showed that the RSM was one of the suitable methods for the EC process to optimize the best operating conditions for target value of effluent arsenic concentration (<10 µg/L) while keeping the OC (energy and electrode consumptions) to minimal. © 2013 © 2013 Balaban Desalination Publications Daha fazlası Daha az

Thermo-economic optimization of superheating and sub-cooling heat exchangers in vapor-compressed refrigeration system

Özkaymak M. | Kurt H. | Recebli Z.

Article | 2008 | International Journal of Energy Research32 ( 7 ) , pp.634 - 647

In this study, superheating and sub-cooling heat exchangers in vapor-compressed refrigeration system are analyzed from thermodynamics and economical (refrigeration system operation cost, investment cost) viewpoints. Using four different refrigerants (R22, R502, R134a and R404a), the temperature of condenser at the interval of (35-55°C) and temperature of evaporator at the interval of (- 10 to 10°C) have been obtained from the calculation process. The second law analysis (analysis of irreversibility) of a reffigeration system is carried out and then the whole system is optimized thermo-economically. As a result of calculations, optim . . .um superheating and sub-cooling, temperatures of heat exchanger (superheating, sub-cooling) areas corresponding to these temperatures are obtained. Copyright © 2007 John Wiley & Sons, Ltd Daha fazlası Daha az

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