Loading...
Search for: mehrabi--a
0.183 seconds

    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
    Abstract
    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,... 

    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 28-31 ; 2227524X (ISSN) Piryaei, M ; Motamedi, A ; Mehrabi Far, A ; Sharif University of Technology
    Science Publishing Corporation Inc  2018
    Abstract
    This experiment investigates the effects of utilizing Rahnama cultivar with high non-starchy polysaccharide content and supplementation of xylanase enzyme in poultry feed on the productivity features, nutrient digestibility and intestinal enzymes activity of 21-47 week laying hens. The experiment was conducted quite randomly and in factorial design that included eight treatments with 4 wheat levels (zero, 23, 46 and 69% that contained 1.8, 2.0, 2.2, 2.4% of xylose respectively) and two level enzymes (with and without enzyme) and 5 replications (6 hens) in each replication. During the experiment, by xylose level increase in diet, the weight (p > 0.05) and mass of the egg (p > 0.01) decreased... 

    Numerical optimization of three-cavity magneto mercury reciprocating (MMR) micropump

    , Article Engineering Applications of Computational Fluid Mechanics ; Volume 15, Issue 1 , 2021 , Pages 1954-1966 ; 19942060 (ISSN) Mehrabi, A ; Mofakham, A. A ; Shafii, M. B ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    Abstract
    The operation of the three-cavity magneto mercury reciprocating (MMR) micropump, whose prototype were presented in an earlier companion paper, was numerically explored. In the three-cavity MMR micropump, three mercury slugs are moved by a periodic Lorentz force with a phase difference in three separate cavities. A consecutive motion of the slugs in their cavities transfer air from the inlet to the outlet. Two-dimensional OpenFOAM simulations were carried out to explore the influence of electric current excitation phase difference and back-pressure. The numerical simulations predicted the MMR micropump (with no valve) with a phase difference of (Formula presented.) and (Formula presented.)... 

    Bounds on the approximation power of feed forward neural networks

    , Article 35th International Conference on Machine Learning, ICML 2018, 10 July 2018 through 15 July 2018 ; Volume 8 , 2018 , Pages 5531-5539 ; 9781510867963 (ISBN) Mehrabi, M ; Tchamkerten, A ; Isvand Yousefi, M ; Sharif University of Technology
    International Machine Learning Society (IMLS)  2018
    Abstract
    The approximation power of general feedforward neural networks with piecewise linear activation functions is investigated. First, lower bounds on the size of a network are established in terms of the approximation error and network depth and width. These bounds improve upon state- of-the-art bounds for certain classes of functions, such as strongly convex functions. Second, an upper bound is established on the difference of two neural networks with identical weights but different activation functions. © The Author(s) 2018  

    Effect of alumina nanoparticles on the microstructure and mechanical durability of meltspun lead-free solders based on tin alloys

    , Article Journal of Alloys and Compounds ; Volume 688 , 2016 , Pages 143-155 ; 09258388 (ISSN) Mehrabi, K ; Khodabakhshi, F ; Zareh, E ; Shahbazkhan, A ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    As one of the key technologies for high performance electronic devices, composite solders have been recently developed to improve thermal and mechanical properties of solder joints. In this research, melt spinning was employed to fabricate a lead-free based nanocomposite solder for electronic application materials via introducing Ni-coated Al2O3 nanoparticles (0.1 wt%) into a Sn-Ag-Cu ternary eutectic alloy during rapid solidification. These surface-modified nanoparticles were synthesized by an in situ chemical reduction method. The effect of rapid solidification on the distribution of reinforcing nanoparticles, microstructural evolution, and solderability of the tin alloy were studied.... 

    Monotonic behavior of C and L shaped angle shear connectors within steel-concrete composite beams: An experimental investigation

    , Article Steel and Composite Structures ; Volume 35, Issue 2 , 2020 , Pages 237-247 Shariati, M ; Tahmasbi, F ; Mehrabi, P ; Bahadori, A ; Toghroli, A ; Sharif University of Technology
    Techno Press  2020
    Abstract
    Shear connectors are essential elements in the design of steel-concrete composite systems. These connectors are utilized to prevent the occurrence of potential slips at the interface of steel and concrete. The two types of shear connectors which have been recently employed in construction projects are C- and L-shaped connectors. In the current study, the behavior of C and L-shaped angle shear connectors is investigated experimentally. For this purpose, eight push-out tests were composed and subjected to monotonic loading. The load-slip curves and failure modes have been determined. Also, the shear strength of the connectors has been compared with previously developed relationships. Two... 

    A new semi-empirical wind turbine capacity factor for maximizing annual electricity and hydrogen production

    , Article International Journal of Hydrogen Energy ; Volume 45, Issue 32 , 2020 , Pages 15888-15903 Sedaghat, A ; Mostafaeipour, A ; Rezaei, M ; Jahangiri, M ; Mehrabi, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The capacity factor is an important wind turbine parameter which is ratio of average output electrical power to rated electrical power of the wind turbine. Another main factor, the AEP, the annual energy production, can be determined using wind characteristics and wind turbine performance. Lower rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a rated wind speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor... 

    Silver fiber fabric as the current collector for preparation of graphene- based supercapacitors

    , Article Electrochimica Acta ; Volume 227 , 2017 , Pages 246-254 ; 00134686 (ISSN) Mehrabi Matin, B ; Shahrokhian, S ; Iraji zad, A ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    During the past few years, a considerable attention has been devoted to the development of textile- based energy storage devices and wearable electronics applications. In this paper, for the first time, we report a flexible high performance graphene-based supercapacitor using silver fiber fabric as the current collector. The silver fiber fabric offers remarkable advantages such as light weight, mechanical flexibility and ease of integration with electronic textiles, which well-suited for wearable energy storage devices. A new hybrid material of graphene-silver fiber fabric (rGO/SFF) was prepared through a facile electrophoretic deposition of graphene and being used as a binder-free flexible... 

    Effect of financial and technical uncertainty on distribution network reconstruction project selection

    , Article IET Conference Publications ; Volume 2013, Issue 615 CP , 2013 ; 9781849197328 (ISBN) Mostafavi, M ; Eini, B. J ; Mehrabi, A ; Naghdi, M ; Sharif University of Technology
    2013
    Abstract
    Distribution companies are pressurized into investing in many projects for ensuring customer satisfaction and increasing their profitability. There are a lot of feasible projects that may help companies to improve their services, but resources for accomplishing them are limited. Therefore, financial subjects are crucially important for related decision making and budget allocation is a bone of contention between different departments of companies. Project net present value (NPV), which depends on investment, expected annual profit, interest rate and inflation rate, is realistic criterion of project economic value. Interest rate and inflation rate are not predefined coefficients.... 

    Studying wave optics in the light curves of exoplanet microlensing

    , Article Monthly Notices of the Royal Astronomical Society ; Volume 431, Issue 2 , 2013 , Pages 1264-1274 ; 00358711 (ISSN) Mehrabi, A ; Rahvar, S ; Sharif University of Technology
    2013
    Abstract
    We study the wave optics features of gravitational microlensing by a binary lens composed of a planet and a parent star. In this system, the source star near the caustic line produces a pair of images in which they can play the role of secondary sources for the observer. This optical system is similar to the Young double-slit experiment. The coherent wavefronts from a source on the lens plane can form a diffraction pattern on the observer plane. This diffraction pattern has two modes from the close- and wide-pair images. From the observational point of view, we study the possibility of detecting this effect through the Square Kilometre Array (SKA) project in the resonance and... 

    Investigation of Fracture Toughness of Epoxy Resins by Addition of CNT and Rubber Microparticles

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Fatemeh (Author) ; Bagheri, Reza (Supervisor)
    Abstract
    Epoxy resins are relatively brittle and have low resistance to crack propagation. It is common to add rubber particles to improve crack resistance in epoxies, although these particles may deteriorate the strength of the matrix. Different nanomaterials are used to overcome the inherent brittleness of epoxies and to keep the mechanical properties. Among them, carbon nanotubes has been attracted many attentions. Fractue behavior and mechanical properties of two kind of novel nanocomposites, i.e, epoxy/carbon nanotube and epoxy/rubber/carbon nanotube are investigated in current study. Electron microscopy investigations were done to assure the CNTs distribution and fracture mechanisms as well.... 

    Performance Evaluation of Machine Learning and Statistical Approaches for Wildfire Modeling and Prediction

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Majid (Author) ; Moghim, Sanaz (Supervisor)
    Abstract
    Wildfires are complex phenomena with many indeterminate and highly unpredictable driving factors that have remained unresolved. During the last decade, machine learning methods have successfully excelled in wildfire prediction as an alternative to traditional field research methods by elucidating the relationship between historical wildfire events and various important variables. The main purpose of this research is to evaluate the random forest machine learning approach and the logistic regression statistical approach to prepare a wildfire susceptibility map using data related to historical wildfires and effective variables in the Okanogan region in Washington province of the United States... 

    Post-consumer recycled high density polyethylene/polypropylene blend with improved overall performance through modification by impact polypropylene copolymer: morphology, properties and fracture resistance

    , Article Polymer International ; Volume 70, Issue 12 , 2021 , Pages 1701-1716 ; 09598103 (ISSN) Mehrabi Mazidi, M ; Sharifi, H ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    Abstract
    The effect of an impact polypropylene copolymer (IPC) having excellent stiffness–toughness balance on the microstructure and properties of a blend comprising 80 wt% recycled high density polyethylene (rHDPE) and 20 wt% recycled isotactic polypropylene (rPP) was studied. Morphological observations revealed improved interfacial interactions, a finer dispersion state and a more homogeneous phase morphology upon IPC incorporation into the blend up to 20 wt%. Flexural modulus, flexural strength, tensile strength and tensile ductility were steadily increased with IPC loading, and exhibited 13%, 14%, 35% and 520% improvement at 20 wt% IPC. A monotonic rise in Izod impact energy, accompanied by a... 

    Cooperative Data Aggregation in Wireless Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Mehrabi Koushki, Masoud (Author) ; Movaghar, Ali (Supervisor)
    Abstract
    Minimizing energy consumption is the most important concern in wireless sensor networks (WSNs). Cooperative multiple-input multiple-output (MIMO) and data aggregation are two promising techniques to conserve energy in network nodes by coordinating their transmissions through cooperative communications along with eliminating the inherent redundancy of raw data for transmissions. In this thesis, with the goal of reducing energy consumption, we present a dynamic clustering framework for combined used of cooperative MIMO and data aggregation in cluster-based WSNs. We derive a new and more general energy model for computing energy consumption of cooperative data aggregation in wireless sensor... 

    Numerical Fatigue Investigation of Composites Honeycomb Structures Using Four Point Bending Loading Specimen

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Hadi (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    In this thesis, design and analyses of honeycomb structures are investigated. Primary goal is to develop an equivalent orthotropic material model that is a good substitute for the actual honeycomb core. By replacing the actual honeycomb structure with the orthotropic model, during the finite element analyses, substantial advantages can be obtained with regard to ease of modeling and model modification, solution time and hardware resources . To figure out the best equivalent model among the approximate analytical models that can be found in the literature, a comparison is made. First sandwich beams with four different honeycomb cores are modeled in detail and these are accepted as reference... 

    Wave Optics Effects in Microlensing of a Binary Lenses

    , Ph.D. Dissertation Sharif University of Technology Mehrabi Rahmanpour, Ahmad (Author) ; Rahvar, Sohrab (Supervisor)
    Abstract
    In this thesis, we investigate two subjects in gravitational microlensing. In first part we study wave optics effect in light curve of a binary system. Gravitational lensing occurs when light deflects in a gravitational field. This deflection produces multi-images from real one. In microlensing regime, images can not be detected separately and gravitational lensing appears as magnifying source’s flux . Microlensing has been studied mostly in geometric optics regime. At larger wavelengths, mostly at radio wavelengths, we expect to see the effects of wave optics in microlensing. Stars at radio wave are faint and to detect them we need a powerful radio telescope. In the near future, SKA (Square... 

    Numerical Simulation of Magneto Mercury Reciprocating Micropump

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Ali (Author) ; Shafii, Mohammad Behshad (Supervisor)
    Abstract
    In this investigation Magneto Mercury Reciprocating Micrpump (MMRM) the combination of Magneto-Hydrodynamic and Reciprocating micropumps has been analyzed. To achieve the analytical and numerical solution of one-tank and three-tank MMRM, the momentum, continuity, volume fraction and magnetohydrodynamic equations have been presented. The dimensionless analytical solution of one-phase and two-phase three dimensional MHD flow in the condition of using constant current and potential electrical source, has been offered.
    The boundary between mercury and air has been tracked via VOF method in OpenFOAM software. VOF equation has been solved by explicit method with variable time step and maximum... 

    Development of a Conceptual Model for Heat Recovery from Exhaust Gases of Electric Arc Furnace

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Mohammad Reza (Author) ; Saboohi, Yadollah (Supervisor)
    Abstract
    Steel in Iran is mainly produced by EAFs. One of the most fundamental issues in the field of electric arc furnace is to foresight methods to reduce energy consumption and emissions. A model is presented in the present research work that avails itself to analysis of mass and energy recovery simultaneously. The proposed model includes three major elements: scrap pre-heating, sponge iron pre-heating and inert gases pre-heating. An important feature of this approach is to preheat sponge iron. Mathematical model for preheating scrap has been developed on the basis of CONSTEEL technology. Also the model for sponge iron and inert gases preheating has been formulated based on the literature review.... 

    Theoretical and Numerical Simulation of a Solar Collector for Direct Steam Generation

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Pouria (Author) ; Morad, Mohammad Reza (Supervisor)
    Abstract
    Direct steam generation (DSG) process using linear FRESNEL collectors has been developed widely in recent years and is one of the most promising solar technologies for thermal power generation, Industrial processes and domestic usage. In this process water as heat transfer fluid (HTF) is heated through a solar field. Continuous breakthroughs are being achieved on improvement of these collectors. A multi-phase CFD model is developed to calculate the wall temperature of linear Fresnel absorber tubes and fluid properties including temperature, velocity, and pressure. In order to design the collector field and identify the critical condition such as overheating of the absorber tubes, modeling of... 

    Design and Construction of a Single Axis Stable Platform Using the Model-Based Design Approach

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Mohammad Hossein (Author) ; Nobahari, Hadi (Supervisor)
    Abstract
    The perpuse of this thesis is to design and fabricate a laboratory one degree of freedom stable platform under turbulences by model-based design method. To do this, different parts of the system were first modeled in the Solidworks software and then fabricated with various tools. With proper assembly of electronic and mechanical components, the original body of the system was created. Then, the controller motor with a stable platform which is attached to it was modeled and simulated in MATLAB software. Then, the parameters of the equations were calculated using standard identification tests and TCACS optimization algorithm. One of the challenges of this thesis is the malfunction of the...