Volume 2, Issue 9, December 2011
Modification of SST Turbulence Model on the Basis of Delay Time Concept for Unsteady Flows
Mahtab. Mansoor, Mahmoud. Pasandidefard and Ali. Khaleghi
Department of Mechanical Engineering, Ferdowsi University Of Mashhad, Mashhad, Iran
Abstract– In this paper, the modification of SST turbulence model for an accelerated flow in a pipe is studied. In order to determine the characteristics of the fluid under the non-periodic accelerating conditions and using water as the working fluid, SST model has been investigated. Ramp-up experiments were performed in which the ramp rate of the bulk velocity was varied by imposing excursions of flow rate during which the Reynolds number increased linearly from an initial value of 7000 to a final value of 45200 in periods of time which ranged from 5 sec to 45 sec. It has been presented that the numerical values of turbulent kinetic energy, before the end of the delay time are less than the corresponding experimental data. In this research, it has been shown that by adding suggested factors to the third term of non-dimensional specific dissipation equation of SST model, which introduces the turbulence diffusion, the numerical results will be very close to the present experimental data. The modifying factor has been extracted on the basis of the delay time concept. This process is performed in two stages; before the end of the delay period and after that. This method of modification has been also applied for three different fluids and radius, and the results have been compared with the original turbulence model.
Keywords—Unsteady Turbulent Flow, SST Turbulence Model, Delay Time and Pipe Flow
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Economic Load Dispatch and DC-Optimal Power Flow Problem- PSO versus LR
Rahmat Azami, Mohammad Sadegh Javadi and Ghasem Hematipour
Department of Electrical Engineering, Shoushtar Branch, Islamic Azad University, Shoushtar, Iran
Abstract– Economic Load Dispatch (EDC) and Direct Current Optimal Power Flow (DCOPF) are the most important techno-economical issues in the power system operation. In this paper, two approaches are incorporated in the EDC and DCOPF problems. One of them is a mathematical optimization technique, Lagrangian Relaxation (LR) and the second is a heuristic one, Particle Swarm Optimization, (PSO). Both techniques have strong and weak points. The LR technique is based on the derivatives and the PSO is a non- derivative technique. These approaches are effective tools which can be implemented for short-term and long-term power system analysis, especially for economic analysis of restructured power systems. The DCOPF methodology has been considered for LMP calculation in LR, which is not available in PSO techniques. In the other hand, PSO technique may be able to provide the optimal solution, where LR usually getting stuck at a local optimum in a large scale power system. The simulation results show that the presented methods are both satisfactory and consistent with expectation.
Keywords—Particle Swarm Optimization, Lagrangian Relaxation, DC-Optimal Power Flow, Economic Load Dispatch and Power System Economic
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Overview and Analysis of Internet Protocol Television
Junaid Qayyum, Shahzad Rizwan, Rashid Zubair, Abdul Sattar, Usman, M. Lal, Shahzad Hameed, Rashid Azim and Asad Malook
Gandhara University of Sciences Peshawar, Pakistan
Institute of Business and Management Sciences, KPK Agriculture University, Peshawar, Pakistan
Abstract– Internet Protocol Television (IPTV) is a rapidly maturing technology for the delivery of broadcast TV and other media-rich services over a secure, end-to-end operator managed broadband IP data network. IPTV broadly encompasses a rich functionality that ranges from the acquisition, encoding and decoding, access control and management of video content, to the delivery of digital TV, movies on demand, viewing of stored programming, Personalized program guides, and a host of interactive and multimedia services. IPTV is distinctly different from “Internet Video” that simply allows users to watch videos, like movie previews and webcams, over the Internet in a “best effort” fashion with no into- end service management and quality of service considerations. This paper is an overview of the new emerging IPTV technology. Our future work will be focusing on IPTV Quality of Experience, its architecture, security threats and its possible solutions and so on.
Keywords—IPTV, Analysis, Protocol and Architecture
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A Theoretical Investigation of SiO2-Water Nanofluid Heat Transfer Enhancement over an Isothermal Stretching Sheet
Aminreza Noghrehabadi, Mehdi Ghalambaz and Mohammad Ghalambaz
Department of Mechanical Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran
Department of Mechanical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran
Abstract– The objective of the present study is to analyze the heat transfer enhancement of water in the presence of Sio2 nanoparticles over an isothermal stretching sheet. To aim this purpose the boundary layer governing differential equations are transformed to a set of ordinary differential equations using similarity transformations, and they are solved numerically. The effect of SiO2 nanoparticle volume fraction on the heat transfer characteristics is discussed. It is found that the heat transfer rate (reduced Nusselt number) increases with increase of nanoparticle volume fraction.
Keywords—SiO2-Water, Nanofluid and Stretching Sheet
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Finite-element Simulation of Water Jet Machining Process
Ali. Moarrefzadeh
Department of Mechanical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
Abstract– A stern-mounted Water jet installation as used in commercial applications, can be divided into four components: the inlet, the pump, the nozzle and the steering device. In this paper, the Water jet Process is studied and stainless steel temperature field is gained in this process. The thermal effect of Water jet that specially depends on the Water and Nozzle type and temperature field of it in workpiece, is the main key of analysis and optimization of this process, from which the main goal of this paper has been defined. Numerical simulation of machining process in SIMPELC method and by ANSYS software for gaining the temperature field of stainless steel, the effect of parameter variation on temperature field and process optimization are done.
Keywords—Plasma, Shielding Gas, Temperature Field, Stainless Steel and ANSYS-FSI
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Different Kind of Renewable Energy and Exergy Concept
Amir Vosough and Sadegh Vosough
Department of Mechanics, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
Department of Electronics, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
Abstract– Renewable energy has been an important political topic for a long time. 20-30 years ago there was an increasing realization that the earth’s resources are limited and that the world’s dependency on fossil fuel must be reduced. Today, climate problems are on the summit of the international political agenda. In this paper about the different kind of renewable energy and their application has discussed. Also the concept of exergy, application of exergy in various fields and its characteristic has been discussed and a brief comparison between energy and exergy analysis has been done.
Keywords—Energy, Concept, Analysis and Exergy
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Effective Organization Structure Factors on Producing Occupational Stress among Isfahan Province Payame-e-Noor Faculties and Scientific Assistants
Sodabeh Ghalambaz and Sepideh Ghalambaz
Department of Public Administration, Payame Noor University, Tehran, Iran
Department of Library Sciences and Information, Payame Noor University, Tehran, Iran
Abstract– The purpose of this case study is to examine the various factor impacts related to university organizational structure on the faculty occupational stress in Iran-Isfahan Payame-e-Noor university. In order to that, the effects of organization structure factors on scientific assistants are determined. In the present survey, 100 samples out of 300 faculty and scientific staffs working in Isfahan Payam-e-Noor university were selected. Researcher made questionnaires based on 89% cornbuch α and the hypothesis related to the organization structure were completed by the subject. The results were analyzed through statistical analysis methods including, frequency of distribution, T-correlation and variance. The results revealed that there is a significant relationship between organization structure factors and occupational stress on these groups. It was confirmed that important organization structure factors causing occupational stress on these faculties and scientific staff include: low Job perceive value, lack of facilities of promotion, lack of time to study and unbalance relationship between occupation and related salary.
Keywords—Occupation Stress, Scientific Staff and Iran
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Numerical Study of Heat Flux and Temperature of Spherical Stagnation Point Using Trajectory Data and Applying Hot Gas Effects
Mahmood Pasandideh fard, Hamid Mohammadiun, Mohammad Mohammadiun and Omid Mahian
Ferdowsi University Of Mashhad, Mashhad, Iran
Department of Mechanical Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Iran
Young Researchers Club, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Abstract– In this paper, the aero heating of spherical stagnation point is studied. For this purpose, we first calculate the thermodynamic properties behind of the normal shock, for the supersonic flow of the hot gas. After finding these properties, we can calculate the boundary layer properties and then we will be able to determine the heat flux of the spherical stagnation point. This heat flux can be used as a boundary condition in heat transfer code for axial asymmetric case. After computing transient multilayer heat transfer toward the inner side of the shell (which material varies in each layer), we can determine stagnation point temperature and temperature distribution in various layers. To verify the validity of the used numerical procedure in this work, comparisons with the theoretical and experimental results for the X-33 space vehicle have been conducted.
Keywords—Spherical Stagnation Point, Aero Heating, X-33 Space Vehicle and Hot Gas Effects
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The Role of Knowledge Sharing on Individual Performance, Considering the Factor of Motivation- The Conceptual Framework
Fouzia Akram and Rahat Bokhari
Yanbu University College, Royal Commission at Yanbu, KSA
International Islamic University, Islamabad, Pakistan
Abstract– This paper explores the relationship between Motivation, knowledge sharing and individual performance. First, it is argued that Motivation should be associated with Knowledge Sharing, second that Knowledge Sharing and individual Performance are strongly associated to each other. Next, the conceptual relationship between Motivation, knowledge sharing and individual performance has been established. After that, corresponding prepositions on Motivation and knowledge sharing and its relationship on individual performance has been given. This study adds to the understanding of the effects of knowledge sharing on individual performance, and gives implications to the practice of knowledge sharing.
Keywords—Individual Performance, Knowledge Sharing and Motivation
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A Brief Glance at School Libraries and their Management: A Case Study in East Khozestan
Sepideh Ghalambaz and Sodabeh Ghalambaz
Department of Library Sciences and Information, Payame Noor University, Tehran, Iran
Department of Public Administration, Payame Noor University, Tehran, Iran
Abstract– In educational system, school libraries are a separable port of every school and their role in developing teaching concept and its content enrichment cannot be over looked. Considering school libraries importance as the most basic learning centers, makes school libraries attendants to take some appropriate measures or tactics. For taking appropriate measures it is necessary to collect data about the present situation, recognize and explain short comings and problems in order to reach a favorable result. The present study has been designed to achieve this goal, and its main purpose is creating a vivid and clear picture of the school libraries (especially high school) existing conditions and suggesting some solutions for these libraries optimizing in East Khozestan. In order to achieve this objective, a questionnaire in the form of 64 questions were provided and sent to the all (boys' and girls') high schools, in an intermidatory level. The result-base for analyzing data was the contained information in 64 questionnaires out of 67 questionnaires. The low percentage (7.8%) of high school not having library revealed that the majority of these high schools in this city (East Khozestan) did not have a library. Most of these libraries management (64.1%) was performed by instructors teaching Quran or psychological behavior and only (6.2%) of these high school libraries were managed by librarians. This issue reveals an important problem that unspecialized managers administer and control these libraries in East Khozestan.
Keywords—East Khozestan, High School Course, High School Libraries, Learning Centers, Library and Management
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Analysis of Conflicting Information and a Study on Truth-Finder Algorithm
Rathod Maheshwer and Ch. Kishore Kumar
Intrinity Engineering College, India
Abstract– In the world-wide web is the most important information source for most of us. Unfortunately, if there is no guarantee for the correctness of information on the web. The information which we need for us the different web sites often provide conflicting information on a subject, such as different specifications for the same product. Our analysis provides a new problem called Veracity, truth confirmation on the information, which studies how to find true facts from a large amount of conflicting information on many subjects that is provided by various web sites. A general framework for the Veracity problem, and invent an algorithm called TruthFinder, which utilizes the relationships between web sites and their information that a web site is trustworthy if it provides many pieces of true information, and a piece of information is likely to be true if it is provided by many trustworthy web sites. Our study show that TruthFinder successfully finds true facts among conflicting information, and also identifies the disadvantages on existing trustworthy web sites better than the popular search engines.
Keywords—Veracity, Fact, Web Mining and TRUTHFINDER
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Consideration the Important Factor to Power Plant Efficiency
Amir Vosough and Sadegh Vosough
Department of Mechanics, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
Department of Electronics, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
Abstract– In this paper a thermal power plant has been analyzed with use of energy and exergy concept. Irreversibility has calculated in all important part of power plant. Also the effect of ambient temperature to the power plant efficiency has considered. The calculation shows that the most irreversibility has occurred in boiler following with turbines. Increase in ambient temperature with variable condenser pressure is an important factor of efficiency decrease in power plant.
Keywords—Exergy Efficiency, Energy Efficiency, Super Critical Thermal Power Plant and Variable Condenser Pressure
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