Optimal Design of a Direct-Drive Permanent Magnet Synchronous Generator for Small-Scale Wind Energy Conversion Systems

Mohammadali Abbasian,Arash Hassanpour Isfahani 한국자기학회 2011 Journal of Magnetics Vol.16 No.4

This paper presents an optimal design of a direct-drive permanent magnet synchronous generator for a smallscale wind energy conversion system. An analytical model of a small-scale grid-connected wind energy conversion system is presented, and the effects of generator design parameters on the payback period of the system are investigated. An optimization procedure based on genetic algorithm method is then employed to optimize four design parameters of the generator for use in a region with relatively low wind-speed. The aim of optimization is minimizing the payback period of the initial investment on wind energy conversion systems for residential applications. This makes the use of these systems more economical and appealing. Finite element method is employed to evaluate the performance of the optimized generator. The results obtained from finite element analysis are close to those achieved by analytical model.

Double-diffusive natural convection of Al₂O₃-water nanofluid in an enclosure with partially active side walls using variable properties

A. A. Abbasian Arani,E. Kakoli,N. Hajialigol 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11

Natural convection heat and mass transfer characteristics in a square enclosure using variable thermal conductivity and variable viscosityare numerically studied. The fluid in the enclosure is a water-based nanofluid containing Al₂O₃ nanoparticles. The top and bottomhorizontal walls are insulated, while a source (Th, Ch) and a sink (Tc, Cc) are located at the vertical left and right walls as active parts,respectively, with Th>Tc and Ch>Cc. The governing equations in the two-dimensional space are discretized using the control volumemethod. A proper upwinding scheme is employed to obtain stabilized solutions. The study has been carried out for the Rayleigh numbersof 104 to 106, the buoyancy ratios of -5~5, and different configurations of the source and sink. Results are presented in the form of thestreamlines, isotherms and iso-concentraions as well as the average Nusselt and Sherwood numbers. It is observed that average Nusseltnumber is increased by adding the nanoparticles, while average Sherwood number is reduced. Moreover, both Nusselt and Sherwoodnumber are increased as absolute value of the buoyancy ratio or Rayleigh number is increased.

Verification of Lean Construction Benefits through Simulation Modeling: A Case Study of Bricklaying Process

S. Alireza Abbasian-Hosseini,Amin Nikakhtar,Parviz Ghoddousi 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.5

The construction industry includes a large number of specialized areas and disciplines, most of which are based on cyclicalprocesses during the construction phase. With the introduction of the lean construction concept, researchers have begun to apply leanprinciples to construction processes. The research described in this paper applies lean principles to a construction operation usingcomputer simulation. Simulation makes it possible to evaluate the effects of implementing lean principles into construction processesprior to real world application. A case study of the bricklaying process was conducted to quantify and evaluate the results of applyinglean principles. Data required for constructing the simulation model were gathered from the construction site through work and timestudy techniques. Preliminary results show improvement opportunities exist in the bricklaying process due to a high share of nonvalue-adding work. The results of lean principles implementation also reveal that lean principles can enhance the performance of thebricklaying process through more than 40% productivity improvement.

Numerical study of different conduction models for Al2O3-water nanofluid with variable properties inside a trapezoidal enclosure

Ali Akbar Abbasian Arani,Ali Akbar Azemati,Mohammad Rezaee,Behzad Shirkavand Hadavand 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

Natural convection in enclosures containing nanofluids is important in physical and environmental applications. Different models for conduction have been developed because of the importance of this phenomenon in natural convection in enclosures. In this study, effects of conduction models of Chon, Corcione, Khanafer, and Koo and Kleinstreuer on the natural convection inside a trapezoidal enclosure with hot and cold walls are evaluated numerically. The enclosure contains Al 2 O 3 -water nanofluid with variable properties. Effects of the conduction models on fluid flow, natural convection, variations in volume fraction, and diameter of nanoparticles in the models, as well as the variations in the Rayleigh number, are examined. Results show that at Rayleigh numbers of 10 5 and 10 6 , the maximum and minimum values of the average Nusselt number are obtained using the models of Khanafer and Chon, respectively. In all models, the average Nusselt number presents upward and downward trends when the volume fraction of nanoparticles increases but decreases when the diameter of the nanoparticles increases. At Ra = 10 5 in all models, as the volume fraction of nanoparticles increases, the nanofluid provides a higher average Nusselt number compared with the base fluid. By contrast, at Ra = 10 6 , at volume fractions larger than 0.01 and using the model of Chon, the average Nusselt number of the nanofluid is lower compared with that of the base fluid.

Analysis of fluid flow and heat transfer of nanofluid inside triangular enclosure equipped with rotational obstacle

Ali Akbar Abbasian Arani,Mehrdad Kazemi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

Fluid flow, heat transfer and entropy generation inside triangular enclosure equipped with rotational obstacle filled with nanofluid were analyzed numerically by finite difference method and SIMPELR algorithm. Five cases for apex angle, swirling circle radios and spine velocity, swirling circle radios and positions and five cases for wavy wall domain and amplitude were simulated. Although α = 20 has higher average Nusslet number, α = 30 has chosen as optimum apex angle due to meet to geometry problem in next step of optimization process. Optimum wavy wall according to average Nusselt number is constructed with A = 0.05 and D = 1.45π. Radius equal to 0.1 and position equal to 3 has been obtained as optimum geometry between multiple choices. Maximum Nusselt number and entropy generation deal with blades shapes and followed by bricks, platelets and cylinder shapes for nanoparticle volume fraction of between 0.5 and 5 and Rayleigh numbers from 10 3 and 10 6 .

Quantum computing using applied electric field to quantum dots

Meighan, A.,Rostami, A.,Abbasian, K. Techno-Press 2014 Advances in nano research Vol.2 No.1

In recent years, spins of confined carriers in quantum dots are promising candidates for the logical units in quantum computers. In many concepts developed so far, the individual spin q-bits are being manipulated by magnetic fields, which is difficult to achieve. In the current research the recent developments of spin based quantum computing has been reviewed. Then, Single-hole spin in a molecular quantum dots with less energy and more speed has been electrically manipulated and the results have been compared with the magnetic manipulating of the spin.

Charge Carriers and Excitons Transport in an Organic Solar Cell-Theory and Simulation

Ali. Shahini,Karim. Abbasian 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.4

An organic solar cell model is developed that consists of both excitonic and classical bipolar aspects of solar cells. In order to achieve this goal, the photon recycling term is imported into the equations to connect the Shockley-Queisser theory and the classical diode theory. This model for excitonic and classical bipolar solar cells can describe the combined transport and interaction of electrons, holes and excitons. For high mobilities this model reproduces the Shockley Queisser efficiency limit. We show how varying the respective mobilities of the different species changes the operation mode of the solar cell path between excitonic and bipolar. Then, the effect of conduction band offset on transport will be described in this paper. Finally, validity of reciprocity theorem between quantum efficiency and electroluminescence in this model will be discussed.

Electrically Conductive Nanofibers Composed of Chitosan-grafted Polythiophene and Poly(ε-caprolactone) as Tissue Engineering Scaffold

Bakhshali Massoumi,Mojtaba Abbasian,Balal Khalilzadeh,Rana Jahanban-Esfahlan,Hadi Samadian,Hossein Derakhshankhah,Mehdi Jaymand 한국섬유공학회 2021 Fibers and polymers Vol.22 No.1

Two novel electrically conductive nanofibrous scaffolds based on chitosan-grafted polythiophene (CS-g-PTh),and chitosan-grafted polythiophene/poly(ε-caprolactone) (CS-g-PTh/PCL) have been fabricated through electrospinningtechnique, and their performances in tissue engineering (TE) application were preliminary investigated in terms of biological(biocompatibility, biodegradability, and enhancing the cells adhesion and proliferation) as well as physicochemical (composition,electroactivity, conductivity, hydrophilicity, and morphology) features. The conductivities of the CS-g-PTh and CS-g-PTh/PCL nanofibrous scaffolds were determined as 0.09 and 8×10-3 Scm-1, respectively. The developed CS-g-PTh/PCL scaffoldexhibited slightly higher cells proliferation (8.24±0.49) than those of the CS-g-PTh scaffold (7.1±0.38) in time period of 7days. The biodegradability tests using gravimetric approach revealed that the mass loss of CS-g-PTh and CS-g-PTh/PCLelectrospun nanofibers were about 28.1 and 37.3 wt.%, respectively, at the end of experiments (sixth weeks). It was foundthat the electrospinning of CS-g-PTh with PCL improves the nanofibers uniformity as well as the biological features (e.g.,biocompatibility and cell proliferation) of the resultant scaffold.

Electron spin relaxation control in single electron QDs

Mashayekhi, M.Z.,Abbasian, K.,Shoar-Ghaffari, S. Techno-Press 2013 Advances in nano research Vol.1 No.4

So far, all reviews and control approaches of spin relaxation have been done on lateral single electron quantum dots. In such structures, many efforts have been done, in order to eliminate spin-lattice relaxation, to obtain equal Rashba and linear Dresselhaus parameters. But, ratio of these parameters can be adjustable up to 0.7 in a material like GaAs under high-electric field magnitudes. In this article we have proposed a single electron QD structure, where confinements in all of three directions are considered to be almost identical. In this case the effect of cubic Dresselhaus interaction will have a significant amount, which undermines the linear effect of Dresselhaus while it was destructive in lateral QDs. Then it enhances the ratio of the Rashba and Dresselhaus parameters in the proposed structure as much as required and decreases the spin states up and down mixing and the deviation angle from the net spin-down As a result to the least possible value.

Numerical study of laminar-forced convection of Al2O3 -water nanofluids between two parallel plates

M. Hemmat Esfe,A. A. Abbasian Arani,T. Azizi,S. H. Mousavi,S. Wongwises 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

Laminar-forced convection of Al 2 O 3 -water nanofluid between two parallel plates was studied numerically. The channel walls were assumed to be isothermal. The effective viscosity and thermal conductivity of nanofluid were considered as variables, and the effects of applying a variable properties model were investigatedby using two relatively new models. The numerical results were compared to the results obtained from a previous non-variable properties model. Also, the effects of nanoparticle size on the flow and heat transfer within the channel were investigated. The study was carried out using Reynolds numbers between 100-1000, nanoparticle diameters in the 15-75 nm range, and nanoparticle volume fractions in the range 0.01-0.05 nm. The numerical results show that using nanofluid could enhance heat transfer by up to 35 %, compared to the base fluid. In addition, reducing the nanoparticle diameter can enhance heat transfer by up to 15.9 %.