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    Experimental investigation of turbulence specifications of turbidity currents

    , Article Journal of Applied Fluid Mechanics ; Volume 3, Issue 1 , 2010 , Pages 63-73 ; 17353572 (ISSN) Firoozabadi, B ; Afshin, H ; Bagherpour, A ; Sharif University of Technology
    The present study investigates the turbulence characteristic of turbidity current experimentally. The three-dimensional Acoustic-Doppler Velocimeter (ADV) was used to measure the instantaneous velocity and characteristics of the turbulent flow. The experiments were conducted in a three-dimensional channel for different discharge flows, concentrations, and bed slopes. Results are expressed at various distances from the inlet, for all flow rates, slopes and concentrations as the distribution of turbulence energy, Reynolds stress and the turbulent intensity. It was concluded that the maximum turbulence intensity happens in both the interface and near the wall. Also, it was observed that the... 

    The Construction of Scientific Facts from Brono Latour’s Point Of view, Stressing “Laboratory Life”

    , M.Sc. Thesis Sharif University of Technology Solhirad, Moslem (Author) ; Taqavi, Mostafa (Supervisor)
    Social Studies of Science have been taken seriously for some decade recently. The need to these studies after Kuhn is felt in “ The Structure of Scientific Revolution”. One of these approach, allocating to social studies of Scientific Institution, is the so called approach social constructivism. Followers of this approach take Science and scientific discoveris some kind of the Social Constructivism of scintists. Bruno Latour is one of the most famous theorisian of this approach. Studing the laboratory practies, Latour is tring to know about the bihaviour and interaction of scientists. The result of this endivour is “Laboratory Life”, the grand book. Latour is the famous person in the field... 

    Impulse waves effects on coastlines and onshore industrial structures

    , Article Proceedings of the 5th International Conference on Asian and Pacific Coasts, APAC 2009, 13 October 2009 through 16 October 2009 ; Volume 4 , 2010 , Pages 29-36 ; 9789814466561 (ISBN) Najafi Jilani, A ; Ataie Ashtiani, B ; Sharif University of Technology
    Laboratory investigations have been performed on impulse wave's effects near the coastlines such as shoaling effects and run-up. Wave run-up over on smooth impermeable slope are studied in over than 100 experimental tests. The influences of the bed slope angle, incident impulse wave height and still water depth are investigated. The available empirical equations for impulsive wave run-up have been examined by comparison with the collected experimental data. A new equation has been presented for run-up estimation based on the laboratory measurements. It has been compared with others empirical equations and the differences have been discussed. The shoaling effects on the impulse wave feature... 

    Investigation of intestinal enzyme activity and effects of non-starch polysaccharide on it

    , Article International Journal of Engineering and Technology(UAE) ; Volume 7, Issue 4 , 2018 , Pages 23-27 ; 2227524X (ISSN) Piryaei, M ; Motamedi, A ; Mehrabi Far, A ; Sharif University of Technology
    Science Publishing Corporation Inc  2018
    Background and Purpose: Shigella is a human shigellosis and its lipopolysaccharide is identified by 4TLR. The 4TLR is a family of pseudo-TOLL receptors and many immune routes are triggered by stimulating these receptors. Many studies show increasing of 4TLR expression in Mesenchyme stem cells under the influence of lipopolysaccharide. The main objective of this study was to identify the appropriate lipopolysaccharide of Shigella strains by stimulating the immune system for vaccine studies. Materials and Methods: In this experimental study, the stem cell of human Mesenchymal derived from bone marrow was treated by three dilution of 0.1, 0.01, and 0.001 extract of Shigella strains (Flexneri,... 

    Growth and damping of interfacial waves on a diffuse interface

    , Article Environmental Fluid Mechanics ; Volume 16, Issue 2 , 2016 , Pages 401-412 ; 15677419 (ISSN) Fazeli, M ; Jamali, M ; Lawrence, G. A ; Seymour, B ; Sharif University of Technology
    The resonant interaction of surface and internal waves produces a nonlinear mechanism for energy transfer among wave components in oceans, lakes, and estuaries. In many field situations, the stratification may be well approximated by a two-layer fluid with a diffuse interface. The growth and damping rates of sub-harmonic interfacial waves generated by a surface wave through a three-wave resonant interaction are measured in the laboratory. These measurements are compared with theoretical predictions. A diffuse interface reduces the damping rate and increases the growth rate. The predicted growth rate provides excellent comparison with the laboratory measurements. The inclusion of the effects... 

    Experimental investigation of steel frames with single bays of symmetrical y-shaped concentric bracings

    , Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 195-210 ; 10263098 (ISSN) Majid Zamani, S ; Vafai, A ; Aghakouchak, A. A ; Kazemi, M. T ; Sharif University of Technology
    To obtain wider openings than those provided by Chevron bracing, the braces are cranked and connected to the frame corner by an additional brace to form double y-shaped bracings. However, y-bracings are prone to instability and out of plane buckling, accompanied by low hysteretic energy absorption. An experimental research program, focused on y-bracing, was conducted at the BHRC structural engineering laboratory. Specimens presented in this paper include three full-scale single bay frames, with symmetric y-bracing of different cross sections and connection types. In addition, one specimen with Chevron bracing was tested as a reference. A quasi-static cyclic loading was applied increasingly... 

    Effect of road salts on the hydro-mechanical behavior of unsaturated collapsible soils

    , Article Transportation Geotechnics ; Volume 17 , 2018 , Pages 77-90 ; 22143912 (ISSN) Akbari Garakani, A ; Haeri, S. M ; Yazdani Cherati, D ; Ahmadi Givi, F ; Kabiri Tadi, M ; Hashemi, A. H ; Chiti, N ; Qahremani, F ; Sharif University of Technology
    Elsevier Ltd  2018
    Hydro-mechanical behavior of unsaturated collapsible soils can be drastically affected by saline infiltrations. Saline infiltrations into the underlain soil layers of the urban transportation and lifelines due to deicing or existence of traffic pollutants has been a common issue of concern for years in many countries. Additionally, many reports have been published so far, indicating the construction of roads and railways on unsaturated collapsible soils. In this research, hydro-mechanical characteristics of an unsaturated collapsible loessial soil diluted with saturated solutions of three different salts that are frequently involved in transportation infrastructure (namely NaCl, CaCl2 and... 

    Evaluation of imperial performance characteristic of turbocharger turbine and compressor

    , Article 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings, San Francisco, CA, 5 June 2006 through 8 June 2006 ; Volume 2 , 2006 , Pages 1019-1028 ; 1563478153 (ISBN); 9781563478154 (ISBN) Rad, M ; Hajilouy, A ; Shahhosseini, M. R ; Sharif University of Technology
    Performance characteristics of turbocharger turbine and compressor such as efficiency, mass parameter and power are determined experimentally at turbocharger laboratory. Accurate determination of the performance map is significant for manufacturers as well as end users. To this end accurate measurement of test parameters such as temperature, pressure, and speed are required. In this paper an analytic method to predict the measurement uncertainties in turbocharger laboratory, is described. Furthermore the effect of each test parameter on the performance uncertainty is considered. Test parameters that have the most significant influence on the performance uncertainties are identified.... 

    TCP retransmission timer adjustment mechanism using system identification

    , Article Proceedings of the 2004 American Control Conference (AAC), Boston, MA, 30 June 2004 through 2 July 2004 ; Volume 3 , 2004 , Pages 2328-2332 ; 07431619 (ISSN); 0780383354 (ISBN) Haeri, M ; Rad, A. H. M ; American Automatic Control Council; International Federation of Automation Control, IFAC ; Sharif University of Technology
    In this paper, the TCP retransmission timer adjustment mechanism is approached from the system's theoretic point of view. TCP uses a simple recursive system identification algorithm to capture both time variant and time invariant Internet behavior and provides a dynamic Round-Trip Time (RTT) predictor. Based on real Internet data collection, it is observed that when the retransmission timer is adjusted by using the proposed predictor instead of the traditional RTT estimator, its performance increases significantly  

    Design and implementation of TSC type SVC using a new approach for electrical quantities measurement

    , Article 2001 IEEE Porto Power Tech Conference, Porto, 10 September 2001 through 13 September 2001 ; Volume 2 , 2001 , Pages 262-267 ; 0780371399 (ISBN); 9780780371392 (ISBN) Tabandeh, M ; Alavi, M. H ; Marami, M ; Dehnavi, G. R ; Sharif University of Technology
    In this paper, a compact algorithm for balancing the load and correction of power factor in three-phase three-wire system is presented. Susceptances of SVC in each phase are computed as a function of real and imaginary parts of line current. This calculation is based on unity power factor and elimination of negative sequence of currents. A laboratory prototype of Thyristor Switched Capacitor (TSC) at 380V and 45KVAR is designed and implemented. Also, a new approach for measuring active and reactive power, power factor and voltage is presented. This measuring technique is based on integration of current signal over a specific part of voltage signal period. Finally, a brief description of... 

    RANS simulation of interceptor effect on hydrodynamic coefficients of longitudinal equations of motion of planing catamarans

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 37, Issue 4 , July , 2015 , Pages 1257-1275 ; 16785878 (ISSN) Najafi, A ; Alimirzazadeh, S ; Seif, M. S ; Sharif University of Technology
    Springer Verlag  2015
    Understanding and investigation of a high-speed craft dynamics, their longitudinal dynamic instabilities in calm water and behavior in waves are of a great importance. Determination of motion equation coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Therefore, it could be useful in controlling the vessel instabilities. The main purpose of this research is to determine the coefficients of longitudinal motions of a planing catamaran using computational fluid dynamics (CFD) and evaluating the interceptor effect on hydrodynamic coefficients of that, which is widely utilized in controlling the motions of a high-speed... 

    Identification of underwater vehicle hydrodynamic coefficients using model tests

    , Article ASME 2010 International Mechanical Engineering Congress and Exposition, IMECE 2010, Vancouver, BC, 12 November 2010 through 18 November 2010 ; Volume 8, Issue PARTS A AND B , 2010 , Pages 165-173 ; 9780791844458 (ISBN) Sadeghzadeh, B ; Mehdigholi, H ; Sharif University of Technology
    Predicting the hydrodynamic coefficients of an autonomous underwater vehicle (AUV) is important during vehicle design. SUT-2 is an AUV. being developed by the Marine Engineering Research Center of Sharif University of Technology in Iran (MERC). Model tests are done in the marine engineering laboratory towing tank. In tins research, hydrodynamic coefficients are calculated using model test results of an autonomous underwater vehicle. Hydrodynamic forces are also analyzed. These coefficients are used for dynamic modeling and autonomous controller design  

    Educational robot for principles of electrical engineering

    , Article Scientia Iranica ; Volume 25, Issue 3D , 2018 , Pages 1582-1592 ; 10263098 (ISSN) Rahnavard, M ; Alavi, M. H ; Khorasani, S ; Vakilian, M ; Fardmanesh, M ; Sharif University of Technology
    Sharif University of Technology  2018
    An educational robot is described, which is designed and constructed for use in the laboratory of Principles of Electrical Engineering. The discrete nature of design, conforming to a simple block strategy, allows for fairly easy introduction of basic and fundamental concepts of Electrical Engineering to the freshman students, including control, actuation, wireless signal transmission, and analogue/digital conversions. Each block or module represents one or few engineering ideas and helps the students to understand the interplay and connection between system divisions, and enhance their creative thinking. Circuits are designed and implemented such that both structure and functionality of each... 

    Harmful algal blooms (red tide): a review of causes, impacts and approaches to monitoring and prediction

    , Article International Journal of Environmental Science and Technology ; Volume 16, Issue 3 , 2019 , Pages 1789-1806 ; 17351472 (ISSN) Zohdi, E ; Abbaspour, M ; Sharif University of Technology
    Center for Environmental and Energy Research and Studies  2019
    Red tide, an impermanent natural phenomenon including harmful algal blooms, causes changing the color of the sea generally to red or almost brown, and has a serious impact on environment along the coast and aquatic ecosystem. Due to recent extensive steady harmful algal blooms events that cause adverse impacts on human healthsome, aquaculture and tourism industry, and the entire economy of the coastal region, the need of society for realizing these phenomena is much greater than the past. In the recent decades, consideration of algal blooms and determination of bloom-former species and fundamental researches about dynamics of blooms are increased worldwide. Development in technology has... 

    Laboratory investigations on impulsive waves caused by underwater landslide

    , Article Coastal Engineering ; Volume 55, Issue 12 , December , 2008 , Pages 989-1004 ; 03783839 (ISSN) Ataie Ashtiani, B ; Najafi Jilani, A ; Sharif University of Technology
    Laboratory investigations have been performed on the submarine landslide generated waves by performing 120 laboratory tests. Both rigid and deforming-slide masses are considered. The effects of bed slope angle, initial submergence, slide geometry, shape and deformation on impulse wave characteristics have been inspected. Impulse wave amplitude, period, energy and nonlinearity are studied in this work. The effects of bed slope angle on energy conversion from slide into wave are also investigated. Laboratory-based prediction equations are presented for impulse wave amplitude and period in near and far-field and are successfully verified using the available data in previous laboratory and... 

    Design and Development a Prototype Pulsed Plasma Thruster (PPT)

    , M.Sc. Thesis Sharif University of Technology Rezaeiha, Abdolrahim (Author) ; Farshchi, Mohammad (Supervisor)
    Although Pulsed Plasma Thruster (PPT) has first been utilized in a space mission in 1964 but after more than four decades, it is still a space rated technology which has performed various propulsion tasks from stationkeeping tasks to three-axis attitude control for a variety of former missions. With respect to the rapid growth in the small satellite community and the growing interest for smaller satellites in recent years, PPT is one of the promising electric propulsion devices for small satellites (e.g. CubeSats) as the following advantages: simplicity, lightweight, robustness, low power consumptions, low production costs and small dimensions. In spite of the fact that the issues relating... 

    Preliminary Analysis of a Thermo Acoustic Heat Pump (THP) In Lab Scale

    , M.Sc. Thesis Sharif University of Technology Khatib, Abolfazl (Author) ; Ghorbanian, Kaveh (Supervisor)
    thermoacuostic heat pump (THP) is One of the most important thermoacuostic applications which is used for heat lost recovery in industrial applications and civil applications.In this project, we have a quick review on thermoacuostic theory and researches in this field. Also a thermoacuostic heat pump in a lab scale will be designed and analyzed.For achieving this goal, first, mathematical equations of thermoacuostic systems are reviewed; a thermoacuostic heat pump is designed on the base of Tijani method and final model is validated by DeltaEC software. In the next step, after investigating about laboratory equipments which is used in testing process, we generate test matrix and study about... 

    A methodology for analyzing the transient availability and survivability of a system with the standby components in two cases: The identical components and the non-identical components

    , Article Journal of Applied Sciences ; Volume 8, Issue 22 , 2008 , Pages 4105-4112 ; 18125654 (ISSN) Amiri, M ; Ghassemi Tari, F ; Mohtashami, A ; Sadaghiani, J. S ; Sharif University of Technology
    In this study, a method for transient analysis of availability and survivability of a system with the standby components is presented. The availability and survivability of the standby systems is evaluated in two cases, the standby systems with the identical components and the standby systems with the non-identical components. In this study the Markov models, eigen vectors and eigen values for analyzing the transient availability and survivability of the system are employed. The method is implemented through an algorithm which is tested in MATLAB (matrix laboratory) programming environment. The new method enjoys a stronger mathematical foundation and more flexibility for analyzing the... 

    Estimation of damage induced by single-hole rock blasting: A review on analytical, numerical, and experimental solutions

    , Article Energies ; Volume 14, Issue 1 , 2021 ; 19961073 (ISSN) Shadabfar, M ; Gokdemir, C ; Zhou, M ; Kordestani, H ; Muho, E. V ; Sharif University of Technology
    MDPI AG  2021
    This paper presents a review of the existing models for the estimation of explosion-induced crushed and cracked zones. The control of these zones is of utmost importance in the rock explosion design, since it aims at optimizing the fragmentation and, as a result, minimizing the fine grain production and recovery cycle. Moreover, this optimization can reduce the damage beyond the set border and align the excavation plan with the geometric design. The models are categorized into three groups based on the approach, i.e., analytical, numerical, and experimental approaches, and for each group, the relevant studies are classified and presented in a comprehensive manner. More specifically, in the... 

    Expectation maximization based detection for V-BLAST MIMO communication systems and performance evaluation

    , Article 2004 IEEE International Symposium on Spread Spectrum Techniques and Applications, ISSSTA 2004, Sydney, 30 August 2004 through 2 September 2004 ; 2004 , Pages 255-259 Rad, K. R ; Nasiri Kenari, M ; Sharif University of Technology
    Maximum likelihood naturally arises as the target criterion for detection in many applications as well as in layered space-time communications. Nevertheless, the existing algorithms for maximum-likelihood decoding have computational complexity that is not feasible for implementation in practical systems. Applying the Expectation-Maximization algorithm to the Maximum Likelihood detection of layered space-time codes, we iteratively maximize the conditional log-likelihood of a single layer, rather than maximizing the intractable likelihood function of all layers. Computer simulations demonstrate the efficiency of the proposed detection scheme, in comparison to the well known nulling and...