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51.
Mohammad Mahdi Tavakoli Rouhollah Tavakoli Parviz Davami Hossein Aashuri 《Journal of Computational Electronics》2014,13(2):425-431
In the present work, a quantitative phase-field approach is introduced to study the phase-coarsening phenomena in solder alloys, Pb-Sn alloy here. The most important part of this work is to introduce a simple and versatile approach to quantify the experimental and simulation data, without putting into difficulties corresponding to the stochastic nature of phenomenon, in order to compute unknown physical data required to perform numerical simulation. For this purpose, at first, the evolution of microstructure vs. time is studied experimentally by the conventional optical microscopy. Then, unknown physical data, the interface mobility here, is computed by fitting the time evolution of the total interface perimeter of the simulation results to that of the experimental data. In fact, by this approach, the physical data is computed such that it will be applied to predict reality in the subsequent simulations, i.e., the presented method can be accounted as the calibration of the corresponding mathematical model and numerical method. The validity of the presented approach is supported by comparing simulation data to experimental ones. 相似文献
52.
Shams Seyed Amir Arsalan Mirdamadi Shamsoddin Abbasi Seyed Mahdi Kim Daehwan Lee Chong Soo 《Metallurgical and Materials Transactions A》2017,48(6):2979-2992
Metallurgical and Materials Transactions A - In this study, mechanisms of microstructural evolution during hot deformation of Ti-1100 were investigated by EBSD analysis. Misorientation angle... 相似文献
53.
Elnaz Akbari Zolkafle Buntat Aria Enzevaee Mahsa Khoshkhooy Yazdi Mahdi Bahadoran Ali Nikoukar 《Nanoscale research letters》2014,9(1):402
Carbonaceous materials have recently received attention in electronic applications and measurement systems. In this work, we demonstrate the electrical behavior of carbon films fabricated by methane arc discharge decomposition technique. The current-voltage (I-V) characteristics of carbon films are investigated in the presence and absence of gas. The experiment reveals that the current passing through the carbon films increases when the concentration of CO2 gas is increased from 200 to 800 ppm. This phenomenon which is a result of conductance changes can be employed in sensing applications such as gas sensors. 相似文献
54.
Hamideh Einollahzadeh Seyed Mahdi Fazeli 《Science and Technology of Advanced Materials》2016,17(1):610-617
In this paper, we theoretically consider a two dimensional nanomaterial which is a form of hydrogenated penta-graphene; we call it penta-graphane. This structure is obtained by adding hydrogen atoms to the sp2 bonded carbon atoms of penta-graphene. We investigate the thermodynamic and mechanical stability of penta-graphane. We also study the electronic and phononic structure of penta-graphane. Firstly, we use density functional theory with the revised Perdew–Burke–Ernzerhof approximation to compute the band structure. Then one–shot GW (G0W0) approach for estimating accurate band gap is applied. The indirect band gap of penta-graphane is 5.78 eV, which is close to the band gap of diamond. Therefore, this new structure is a good electrical insulator. We also investigate the structural stability of penta-graphane by computing the phonon structure. Finally, we calculate its specific heat capacity from the phonon density of states. Penta-graphane has a high specific heat capacity, and can potentially be used for storing and transferring energy. 相似文献
55.
Fe-Cr-Cu nanocatalyst was synthesized through an inorganic-precursor thermolysis approach and exploited for high temperature water gas shift reaction. The results demonstrated that the method used for the nanocatalyst fabrication led to smaller crystallite size (32.9 nm) and higher BET surface area (127.3 m2/g) compared to those of a reference sample (65.5 nm, 78.6 m2/g) prepared by co-precipitation conventional method. Furthermore, the obtained data for catalytic activity showed that the catalyst prepared via inorganic precursor has better activity than the reference sample in all studied temperatures (350-500 °C) and also exhibited higher catalytic activity than a commercial Fe-Cr-Cu catalyst in higher temperatures (more than 450 °C). 相似文献
56.
Seyed Mohammad Mahdi Mortazavi 《Iranian Polymer Journal》2016,25(8):731-737
High molecular weight with long linear side branches are frequently used in oil pipelines as one of the main classes of drag reducer agents (DRAs). We studied the effects of polymerization conditions, including reaction temperature, monomer concentration and cocatalyst concentration ratio (Al/Ti), on the polymerization yield and molecular weight of the resultant poly(1-hexene) made by Ziegler–Natta catalyst and their consequent effects on the drag reduction efficiency in a loop test. The experimental results verified that the catalyst activity increased from 115 to 220 kgPH/molTi.atm, while the molecular weight of poly(1-hexene) dropped from 2100 to 1030 kDa, as the reaction temperature was increased from 0 to 50 °C. The loop test results also revealed that the highest pressure drop was achieved using the polymer synthesized at 0 °C and by subsequent increase in reaction temperature the pressure drop decreased. Furthermore, the catalyst activity increased from 143 to 262 kgPH/molTi.atm by increasing Al/Ti ratio, while the molecular weight increased up to a maximum level of 1500 kDa at Al/Ti = 143 and decreased at higher cocatalyst contents. Similarly, the results showed the maximum pressure drop of 20 % at Al/Ti = 143. Finally, by increasing monomer concentration, the catalyst activity and polymer molecular weight increased from 75 to 262 kgPH/molTi.atm for the former, and from 700 to 1800 kDa for the latter which resulted in maximum pressure drop by 25 %. Moreover, the pressure drop for each utilized poly(1-hexene) was increased proportionately with DRA’s concentration, and interestingly enough, DRAs were further effective at more turbulent flows with higher Reynolds numbers. 相似文献
57.
A modified particle swarm optimization for disaster relief logistics under uncertain environment 总被引:3,自引:2,他引:1
Ali Bozorgi-Amiri Mohammad Saeid Jabalameli Mehdi Alinaghian Mahdi Heydari 《The International Journal of Advanced Manufacturing Technology》2012,60(1-4):357-371
Relief logistics is one of the most important elements of a relief operation. This paper investigates a relief chain design problem where not only demands but also supplies and the cost of procurement and transportation are considered as the uncertain parameters. Furthermore, the model considers uncertainty for the locations where those demands can arise and the possibility that a number of the facility could be partially destroyed by the disaster. The proposed model for this study is formulated as a mixed-integer nonlinear programming to minimize the sum of the expected total cost (which includes costs of location, procurement, transportation, holding, and shortage) and the variance of the total cost. The model simultaneously determines the location of relief distribution centers and the allocation of affected area to relief distribution centers. Furthermore, an efficient solution approach based on particle swarm optimization is developed in order to solve the proposed mathematical model. At last, computational results for several instances of the problem are presented to demonstrate the feasibility and effectiveness of the proposed model and algorithm. 相似文献
58.
Seyed Abbas Hosseinijou Mahdi Bashiri 《The International Journal of Advanced Manufacturing Technology》2012,58(1-4):211-225
The transfer point location problem has been introduced recently and for the case of minimax objective and planar topology, has only been studied for situations in which demand points are not weighted and have known coordinates. In this paper, we consider the case in which demand points are weighted and their coordinates have bivariate uniform distribution. Also, the problem is developed from a conceptual view and different distance measures are used to make models more applicable in real world situations. The problem is to find the best location for the transfer point such that the maximum expected weighted distance to all demand points through the transfer point is minimized. Depending on assumptions for uniform distributions, two models are considered, convexity conditions are discussed, properties of the optimal solution are obtained and methods to solve the problems are proposed. Finally, numerical examples are given. 相似文献
59.
Mohammad Mahdi Attar Mohammad Haghpanahi Saeid Amanpour Mohammad Mohaqeq 《Journal of Mechanical Science and Technology》2014,28(2):763-771
Magnetic fluid hyperthermia is a new subclass of hyperthermia cancer treatment that can selectively heat up a tumor without damaging the surrounding healthy tissues. Some authors studied the temperature distribution of a magnetically mediated tumor assuming a homogeneous distribution of nanoparticles inside the tumor. Practically speaking, the injected nanoparticles do not usually distribute uniformly throughout the entire tumor, thus leaving some parts of the tumor without nanoparticles. In this study, an inhomogeneous dispersion of nanoparticles inside the tumor is assumed to investigate the tissues’ temperature profiles. The problem is solved for polar coordinate. Also in this study, the heating effect of magnetic fluid in a porcine liver tissue is experimentally examined. Numerical transient solutions are found to be in good agreement with experimental data. 相似文献
60.
El Mahdi Halim Hubert Perrot Ozlem Sel Catherine Debiemme-Chouvy Khalid Lafdi Mama El Rhazi 《International Journal of Hydrogen Energy》2021,46(38):19926-19938
The development of highly efficient catalysts using inexpensive and earth-abundant metals is a crucial factor in a large-scale commercialization of direct methanol fuel cells (DMFCs). In this study, we explored a new catalyst based on copper nanodendrites (CuNDs) supported on carbon nanofibers/poly (para-phenylenediamine) (CNF/PpPD) nanocomposite for methanol oxidation reaction (MOR). The catalyst support was prepared on a carbon paste electrode by electropolymerization of para-phenylenediamine monomer on a drop-cast carbon nanofibers network. Afterwards, CuNDs were electrodeposited on the nanocomposite through a potentiostatic method. The morphology and the structure of the prepared nanomaterials were characterized by transmission electron microscope, scanning electron microscope, energy dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscope. The results suggested that a three-dimensional nanodendritic structure consisting of Cu2O and Cu(OH)2 formed on the hybrid CNF/PpPD nanocomposite. The catalytic performance of CuNDs supported on CNF, PpPD and CNF/PpPD was evaluated for MOR under alkaline conditions. The CNF/PpPD/CuNDs exhibits a highest activity (50 mA cm?2) and stability toward MOR over 6 h, with respect to CNF/CuNDs (40 mA cm?2) and PpPD/CuNDs (36 mA cm?2). This inexpensive catalyst with high catalytic activity and stability is a promising anode catalyst for alkaline DMFC applications. 相似文献