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Search Results: 1 - 10 of 1220 matches for " Mahdi Alshamasin "
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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.

Control of Zero Sequence Braking for a Three-phase Induction Motor Operating from Single-phase Supply with a Controlled Capacitor
Mahdi Salman Alshamasin
Journal of Applied Sciences , 2012,
Abstract: Studying of braking process in the Alternating Current (AC) motors has a great importance due to the need for reducing the braking and stopping time. In many applications, it may be necessary to use a three-phase induction motor on a single-phase supply system. The aims of this study are to investigate and discuss the behavior of a three-phase induction motor operating from single-phase supply when steady-state zero-sequence braking is used. Therefore, mathematical model was developed and the symmetrical components' method was used. To verify the obtained results, an experiment was performed and oscillograms of transient speed were recorded. Results show that the synchronous speed under braking has fallen to one-third of the motoring synchronous speed. And it was also observed that braking time can be controlled by changing the capacitance and rotor resistance values.
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.
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

A Series Solution for Three-Dimensional Navier-Stokes Equations of Flow near an Infinite Rotating Disk  [PDF]
Hamed Shahmohamadi, Mahdi Mohammadpour
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.45014

In this paper, homotopy analysis method (HAM) and Padé approximant will be considered for finding analytical solution of three-dimensional viscous flow near an infinite rotating disk which is a well-known classical problem in fluid mechanics. The solution is compared to the numerical (fourth-order Runge-Kutta) solution and the convergence of the obtained series solution is carefully analyzed. The results illustrate that HAM-Padé is an appropriate method in solving the systems of nonlinear equations.

The Effects of a Health-Based Context on Memory for Advertisements  [PDF]
Sundus Mahdi, Adrian Furnham
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.78117
Abstract: This study looked at whether heath-based advertisements were remembered when placed in a health (congruity) or non-health (incongruity) based television programme and the extent to which participant involvement influenced recall. The study aimed to test whether programme context had an effect on memory for congruent or incongruent advertisements. Sixth-form students watched either a health or non-health programme, with health or non-health centre-break advertisements. Sessions took place during the morning and afternoon. Free recall and cued recall tests were administered to test memory for the TV adverts. Results found no support for the cognitive priming theory, cognitive interference theory or for contrast effects. The study found little evidence to support any theory as to why programme surround should influence the recall of health advertisements. Limitations of the study are considered.
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