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Search Results: 1 - 10 of 401186 matches for " M. Jabbari Ghadi "
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A New Heuristic Method for Solving Unit Commitment Problem in Competitive Environment
M. Jabbari Ghadi,A. Baghramian
International Journal of Soft Computing & Engineering , 2013,
Abstract: In a restructured power market, traditionalscheduling of generating units needs modification. The classicalunit commitment problem aims at minimizing the operationcosts by satisfying the forecasted electricity load. However,under new structure, Generation companies (GENCOs)schedule their generators with an objective to maximize theirown profit by relaxation of the demand fulfillment constraintand without any regard for system social profit, to match thecompetitive market. A Unit Commitment algorithm withcapability of profit maximization plays a significant role insuccessful development bidding strategies of a competitivegenerator. In such an environment, power price turns into animportant factor in decision process. In this paper the authorsutilized a new heuristic technique called ImperialisticCompetitive Algorithm (ICA) to exert Profit Based UnitCommitment (PBUC) problem. In fact, the presented approachassists GENCOs to make a decision, how to schedule generatorsin order to gain the maximum profit by selling adequateamounts of power in power market. The effectiveness of theproposed method to solve generation scheduling optimizationproblem in a day-ahead deregulated electricity market isvalidated on 10 generating unit systems available in theliterature. Comparison of results obtained from simulationverifies the ability of proposed method.
Extracting Structural Parameters of Nanocrystalline ZnO Thin Films Annealed at Different Temperatures
Gh. Solookinejad,M. Jabbari
Journal of Applied Sciences , 2011,
Abstract: Preferred orientation of ZnO thin films deposited by sol-gel deposition technique could be manipulated by changing annealing temperature. In this study, we used spin coating method to coat glass slides with sol-gel ZnO thin films, composed of zinc acetate dihydrate Monoethanolamine (MEA), de-ionized water and isopropanol. The effect of the annealing temperature on the structural properties of these films is investigated. These ZnO thin films were preheated at 275C for 10 min and annealed either at 350, 450 or 550C for 80 min. After heat treatment, each sample was taken out for ex situ Atomic Force Microscopy (AFM) measurements to study the surface morphology. Fractal analysis has been applied to describe the surface morphology and extracting structural parameters of thin films. Thin films also were characterized by X-ray Diffractometery (XRD) method. XRD analysis revealed that the annealed ZnO thin films consist of single phase ZnO with wurtzite structure (JCPDS 36-1451) and show the c-axis grain orientation. Increasing annealing temperature increased the crystallite size and the c-axis orientation of the film after 450C. It was found that there was a significant effect of annealing temperature on the structural parameters of the film such as roughness exponent, fractal dimension and strain along the c-axis.
Distance-Based Scheme for Vertical Handoff in Heterogeneous Wireless Networks
Wail Mardini,Musab Q. Al-Ghadi,Ismail M. Ababneh
Journal of Emerging Technologies in Web Intelligence , 2012, DOI: 10.4304/jetwi.4.1.67-76
Abstract: Seamless vertical handoff between different access networks in the next generation wireless networks remains a challenging problem. A recent vertical handoff scheme that is based on Signal to Interference and Noise Ratio (SINR) may not be the best scheme for selecting the service access point or base station. Although this SINRbased scheme has higher system throughput and lower disconnection probability as compared with other vertical handoff schemes, we presume that the distance is a good criterion for decreasing service disconnection probability and increasing system throughput. The Distance-based Scheme for Vertical Handoff (DSVH) that we propose in this paper for heterogeneous wireless networks is a reactive vertical handoff scheme. We suggest that vertical handoff be based on the Received Signal Strength (RSS) and the distances to access points or base stations, where the main goal of this scheme is to enhance system performance in terms of reducing service disconnection probability and increasing system throughput. The simulation experiments show that our proposed scheme, DSVH, significantly outperforms the SINR-based scheme. It reduces the number of dropped users by 20%. However, the throughput improvrmrnt is insignificant; it is about 1%.
Analysis of Cryogenic Ammonia System for Energy Conservation
B. Raei,F. Shahraki,M. Khorrami,A. Ghadi
Iranica Journal of Energy and Environment (IJEE) , 2010,
Abstract: There are several alternatives to enhance the efficiency of energy usage and to decrease energy losses. Pinch technology is the best method of approach to enhance energy efficiency. Heat exchangers network (HEN) of refrigeration unit of ammonia production process was analyzed to use pinch technology to decrease energy usage. The obtained results showed that pinch technology was unsuccessful for the shaft work targeting capabilities. In contrast, it is posed that for optimization of such systems, one should use the combined pinch and exergy analysis (CPEA) method. In this analysis CPEA method was used in the system. It was observed that the refrigeration system use cold streams for cooling the hot streams. Therefore, retrofitting the refrigeration cycle without changing the main process is impossible. Some suggestions were made for improving the refrigeration system, such as the use of economizer after cooler, multistage cycle and removal of the 111-FFD3 stream. It was also observed that the exchanger 128-E act as an intercooler and the flashed 110-F, 111-F and 112-F act as an economizer. In addition, ammonia refrigerant was used at three different temperatures of -33,-7 and 13.5 C. Also, eliminated the 111-FFD3 stream bring about 2% reduction in exergy loss.
An N-tropic Solution to the Cosmological Constant Problem
Sheikh-Jabbari, M. M.
High Energy Physics - Phenomenology , 2007,
Abstract: Based on the assertion that the cosmological constant problem is essentially a quantum gravity problem, the framework which addresses the cosmological constant problem should also bear a picture for the ``quantum space-time''. In this talk in an attempt to address the cosmological constant problem I suggest to start with noncommutative fuzzy spheres as the toy model for the quantum space-time. In this setting, we show that the cosmological constant problem may be resolved due to the noncommutativity and ``fuzziness'' of the space and the fact that the smallest volume which could be measured in the a quantum space-time is much larger than the naively expected Planckian size. This talk is based on Ref.[1] which has appeared on the arXiv as .
Open Strings in a B-field Background as Electric Dipoles
M. M. Sheikh-Jabbari
Physics , 1999, DOI: 10.1016/S0370-2693(99)00462-1
Abstract: Studying dynamics of open strings attached to a D2-brane in a NS two form field background, we find that these open strings act as dipoles of U(1) gauge field of the brane. This provides an string theoretic description of the flux modifications needed for the DBI action on noncommutative torus.
An N-tropic Solution to the Cosmological Constant Problem
M. M. Sheikh-Jabbari
Physics , 2007,
Abstract: Based on the assertion that the cosmological constant problem is essentially a quantum gravity problem, the framework which addresses the cosmological constant problem should also bear a picture for the ``quantum space-time''. In this talk in an attempt to address the cosmological constant problem I suggest to start with noncommutative fuzzy spheres as the toy model for the quantum space-time. In this setting, we show that the cosmological constant problem may be resolved due to the noncommutativity and ``fuzziness'' of the space and the fact that the smallest volume which could be measured in the a quantum space-time is much larger than the naively expected Planckian size. This talk is based on Ref.[1] which has appeared on the arXiv as hep-th/0605110.
Super Yang-Mills Theory on Noncommutative Torus from Open Strings Interactions
M. M. Sheikh-Jabbari
Physics , 1998, DOI: 10.1016/S0370-2693(99)00122-7
Abstract: Considering the scattering of massless open strings attached to a D2-brane living in the $B$ field background, we show that corresponding scattering upto the order of $\a'^2$ is exactly given by the gauge theory on noncommutative background, which is characterized by the Moyal bracket.
Gauge-flation Vs Chromo-Natural Inflation
M. M. Sheikh-Jabbari
Physics , 2012, DOI: 10.1016/j.physletb.2012.09.014
Abstract: Gauge-flation, non-Abelian gauge field inflation, which was introduced in arXiv:1102.1513 and analyzed more thoroughly in arXiv:1102.1932, is a model of inflation driven by non-Abelian gauge fields minimally coupled to Einstein gravity. In this model certain rotationally invariant combination of gauge fields play the role of inflaton. Recently, the chromo-natural inflation model was proposed arXiv:1202.2366 which besides the non-Abelian gauge fields also involve an axion field. In this short note we show that the model involving axions, indeed allows for various slow-roll trajectories for different values of its parameters: A specific trajectory discussed in arXiv:1202.2366 starts from a "small axion" region, while the trajectory considered in arXiv:1102.1513 corresponds to a "large axion" region.
Classification of Different Branes at Angles
M. M. Sheikh-Jabbari
Physics , 1997, DOI: 10.1016/S0370-2693(97)01550-5
Abstract: In this paper, we consider two D-branes rotated with respect to each other, and argue that in this way one can find brane configurations preserving ${1 \f 16}$ of SUSY. Also we classify different brane configurations preserving ${1 \f 2}$, ${1 \f 4}$, ${3 \f 16}$,${1 \f 8}$, ${1 \f 16}$ of SUSY.
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