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Search Results: 1 - 10 of 1223 matches for " Mahdi Fahiminia "
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Improvment of Free Convection Heat Transfer Rateof Rectangular Heatsink on Vertical Base Plates  [PDF]
HamidReza Goshayeshi, Mahdi Fahiminia, Mohammad Mahdi Naserian
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.34064
Abstract: In this paper, the laminar heat transfer of natural convection on vertical surfaces is investigated. Most of the studies on natural convection have been considered constantly whereas velocity and temperature domain, do not change with time, transient one are used a lot. Governing equations are solved using a finite volume approach. The convective terms are discretized using the power-law scheme, whereas for diffusive terms the central difference is employed. Coupling between the velocity and pressure is made with SIMPLE algorithm. The resultant system of discretized linear algebraic equations is solved with an alternating direction implicit scheme. Then a configuration of rectangular fins is put in different ways on the surface and heat transfer of natural convection on these surfaces without sliding is studied and finally optimization is investigated.
Investigation of Natural Convection Heat Transfer Coefficient on Extended Vertical Base Plates  [PDF]
M. Fahiminia, M. M. Naserian, H. R. Goshayeshi, D. Majidian
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.32022
Abstract: In this research, Computational analysis of the laminar natural convection on vertical surfaces has been in-vestigated. Natural convection is observed when density gradients are present in a fluid acted upon by a gravitational field. Our example of this phenomenon is the heated vertical plate exposed to air, which, far from the plate, is motionless. The CFD simulations are carried out using fluent software. Governing equa-tions are solved using a finite volume approach. Coupling between the velocity and pressure is made with SIMPLE algorithm. The resultant system of discretized linear algebraic equations is solved with an alternat-ing direction implicit scheme. Then a configuration of rectangular fins is put in different ways on the surface and natural convection heat transfer coefficient on these no slope surfaces is studied and finally optimization is done.
Towards Economic Single-Phase Motor  [PDF]
Mahdi Alshamasin
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.59058

Studying of operation balance in single-phase induction motors is an issue of interest due to the need for reducing the power consumption and increasing the motors’ life. The paper focuses on improving the motor performance by balancing the stator phase operation for the most common-used connection diagrams of single-phase capacitor-run induction motors (SPCRIMs) and three-phase induction motors (TPIMs) operating from single-phase supply (SPS). Therefore, a mathematical model is used to balance the motor operation by varying the frequency supply voltage. Characteristics of balancing parameters are investigated, various methods of motor balancing are presented and comparisons were done among these balancing methods.

Confirmation of Monod Model for Biofiltration of Styrene Vapors from Waste Flue Gas
Reza Dehghanzadeh,Babak Roshani,Mahzar Asadi,Mohammad Fahiminia
Health Promotion Perspectives , 2012, DOI: 10.5681/hpp.2012.029
Abstract: Background: The objective of this research was to investigate the kinetic behavior of the biofil-tration process for the removal of styrene.Methods: A three stage compost based biofilter was inoculated with thickened activated sludge. The reaction order rate constants were obtained from continuous experiments and used as the specific growth rate for the Monod equation.Results: The measured concentration profiles show a linear dependence on the bed height in the biofilter at higher loadings, such as 75 and 45 g m-3 h-1. This is the condition of reaction limitation for a reaction with zero-order kinetics. From the experimental data, maximum elimination capac-ity (ECmax) was estimated to be 44, 40 and 26 g m-3 h-1 at empty bed retention times (EBRTs) of 120, 60 and 30 s, respectively. However, at lower loadings, the measured concentration profile of the biofilter is one of exponential increase, which is the condition of both reaction and diffusion limitations for a reaction with zero-order kinetics. Maximum elimination capacities found from the experimental results were the same as Monod model predictions. Both the experimental re-sults and the model predictions showed the influence of EBRT on the removal rate of styrene, particularly for the highest loading rate.Conclusion: In terms of the practical applications of the proposed models have the advantage of being simpler than Monod kinetics and Monod kinetics requires a numerical solution.
Survey of Optimal Methods for the Control of Cockroaches in Sewers of Qom City
M. Fahiminia,A. Paksa,M. Shams,M. Fazlzadeh davil
Iranian Journal of Health and Environment , 2010,
Abstract: "n "nBackgrounds and Objectives: Domestic sewers and wastewater treatment plants are suitable places for the growth of some types of Cockroaches. Annually the water and wastewater company of Qom city make considerable attempts to overwhelm the problem. The current study is aimed to determine types of Cockroaches and select the optimal methods for their control."nMaterials andMethods: In this study, 120 manholes are selected in different locations of Qom city, the numbers of Cockroaches are counted and the Cockroaches are classified into different groups. Then, each group are faced to different insecticides Including Simperator, Diazinon , Dursban Ec, Faikam, Sipermetrin, Icon, Deltametrina and Sulfac. One group of manholes was considered as blank sample during one month. Counting and determination of Cockroaches in these manholes conducted before using insecticides and also five months after it."nResults: the study showed that all sewers were 100% polluted by Cockroaches. The number of Cockroaches in manholes range from minimum 4 to maximum 3600 in each manhole. The applied of insecticides including Dursban Ec, Simperator, Sulfac, Dursban, and Deltametrina are used 2 gr in 100 square meter of area of each sewer. The Cockroaches population reduced to approximately zero after application of these insecticides. Spraying sewers by Simperator controlled 100% of Cockroaches."nConclusion: the most effective method for the control of Cockroaches was usage of 2 gr of Dursban (Ec) in squaremeter of area in the beginning of warmseason.If we use 1-1/5months interval between the time of spraying insecticide in selected wells, with using simperator and dursban (Ec) we can overwhelm Cockroaches using Simperator and Dursban Ec. The results of statistical analysis show that reduction of number of coackroaches in one month after using poison is significant (P-value< 0.05). But after 5months it lose meaningful in all of them.Also, reduction of number of coackroachesin blank manholes was not statistically significant.
A New Method of Voiced/Unvoiced Classification Based on Clustering  [PDF]
Mojtaba Radmard, Mahdi Hadavi, Mohammad Mahdi Nayebi
Journal of Signal and Information Processing (JSIP) , 2011, DOI: 10.4236/jsip.2011.24048
Abstract: In this paper, a new method for making v/uv decision is developed which uses a multi-feature v/uv classification algorithm based on the analysis of cepstral peak, zero crossing rate, and autocorrelation function (ACF) peak of short-time segments of the speech signal by using some clustering methods. This v/uv classifier achieved excellent results for identification of voiced and unvoiced segments of speech.
Turbidimetric Determination of Hydrocarbon Contamination in Passaic River Sediments and Refinery Polluted Soils  [PDF]
Mahmood Mahdi Barbooti
Journal of Environmental Protection (JEP) , 2011, DOI: 10.4236/jep.2011.27104
Abstract: A rapid method is described for the determination of petroleum hydrocarbons in soil samples. The method is based on the extraction of hydrocarbons by a solvent and the treatment of the solution with an aqueous solution of a surfactant to release the hydrocarbons to the water phase in the form of a stable emulsion. The emulsion is then utilized to measure the hydrocarbon content by turbidimetry. The effects of various operating parameters including the surfactant solution composition and time of extraction and time of mixing with the releasing solution are investigated. The stability of the emulsion was improved in acid environment containing and electrolyte. The turbidity values (T) were related with hydrocarbon concentration in the extract (C) by the following equation. Turbidity = 2.75 C + 205.7. With R2 = 0.9929. The soil hydrocarbon content (SHC) measured in µg/g can then be calculated using the formula: SHC = [Extract Vol. (mL) x C]/Sample Wt (g). The results correlated well with the results of total hydrocarbons in soils determined by standard methods. The method was applied for the estimation of hydrocarbons in Passaic river sediments taken from various locations and depths. For field work the method was used to supply data on the hydrocarbon contamination of soil samples taken within an oil refinery and a monitoring well drilled within heavy hydrocarbon waste dumping location.
Evaluating Effects of Two Alternative Filters for the Incremental Pruning Algorithm on Quality of Pomdp Exact Solutions  [PDF]
Mahdi Naser-Moghadasi
International Journal of Intelligence Science (IJIS) , 2012, DOI: 10.4236/ijis.2012.21001
Abstract: Decision making is one of the central problems in artificial intelligence and specifically in robotics. In most cases this problem comes with uncertainty both in data received by the decision maker/agent and in the actions performed in the environment. One effective method to solve this problem is to model the environment and the agent as a Partially Observable Markov Decision Process (POMDP). A POMDP has a wide range of applications such as: Machine Vision, Marketing, Network troubleshooting, Medical diagnosis etc. In recent years, there has been a significant interest in developing techniques for finding policies for (POMDPs).We consider two new techniques, called Recursive Point Filter (RPF) and Scan Line Filter (SCF) based on Incremental Pruning (IP) POMDP solver to introduce an alternative method to Linear Programming (LP) filter for IP. Both, RPF and SCF have solutions for several POMDP problems that LP could not converge to in 24 hours. Experiments are run on problems from POMDP literature, and an Average Discounted Reward (ADR) is computed by testing the policy in a simulated environment.
Wavelet Density Estimation and Statistical Evidences Role for a GARCH Model in the Weighted Distribution  [PDF]
Mohammad Abbaszadeh, Mahdi Emadi
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.42061

We consider n observations from the GARCH-type model: Z = UY, where U and Y are independent random variables. We aim to estimate density function Y where Y have a weighted distribution. We determine a sharp upper bound of the associated mean integrated square error. We also make use of the measure of expected true evidence, so as to determine when model leads to a crisis and causes data to be lost.

Using AdaBoost Meta-Learning Algorithm for Medical News Multi-Document Summarization  [PDF]
Mahdi Gholami Mehr
Intelligent Information Management (IIM) , 2013, DOI: 10.4236/iim.2013.56020

Automatic text summarization involves reducing a text document or a larger corpus of multiple documents to a short set of sentences or paragraphs that convey the main meaning of the text. In this paper, we discuss about multi-document summarization that differs from the single one in which the issues of compression, speed, redundancy and passage selection are critical in the formation of useful summaries. Since the number and variety of online medical news make them difficult for experts in the medical field to read all of the medical news, an automatic multi-document summarization can be useful for easy study of information on the web. Hence we propose a new approach based on machine learning meta-learner algorithm called AdaBoost that is used for summarization. We treat a document as a set of sentences, and the learning algorithm must learn to classify as positive or negative examples of sentences based on the score of the sentences. For this learning task, we apply AdaBoost meta-learning algorithm where a C4.5 decision tree has been chosen as the base learner. In our experiment, we use

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