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Total 80 records

    Behran Mehr Peyma's Activities Analysis

    , M.Sc. Thesis Sharif University of Technology Haghighi, Erfan (Author) ; Miremadi, Alireza (Supervisor)
    Abstract
    Behran Mehr Peyma (BMP) is an elevator equipment producer and trader in Iran which was established in 2004. At first they are producing some regular parts of elevator and then during these years they are trying to improve their work and expand their business till they have the 15% market share in elevator market in Tehran.In this thesis I am trying to use the SWOT and PETS methods to show the exact situation of BMP comparing to the whole market considering the competitors.During this reduction in the market I suggest to BMP to change some policies and use some of its strength to attract some new customers, changing their brand name and find a relation to contribute in some tenders and... 

    The Performance in Temperature Increas of Bolted Slant Endplate Connection

    , M.Sc. Thesis Sharif University of Technology Zahmatkesh, Farshad (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    The main goal of this research is to evaluate the vertical and slant bolted endplate connections performance in steel moment frame structures under thermal effect in elastic range for two cases. In the first case, frictionless and in the second case slips with friction are considered. By finite element analysis, the connections are simulated to study the performance and verify simplified models of vertical and slant bolted endplate connections due to increase in temperature. The results of a vertical bolted endplate connection and a slant bolted endplate connection due to increase in temperature are compared the effect of slope of end plate reduction of axial force on beam is investigated.... 

    The Study of the Behaviour and Performance of a New Elevated Tank

    , M.Sc. Thesis Sharif University of Technology Tajmir Riahi, Hossein (Author) ; Khansari, Vahid (Supervisor)
    Abstract
    Various types of tanks are used to store a variety of liquids, drinking water, chemicals, petrochemicals, and liquefied natural gas. Of these, one type is ‘elevated tank’ which is used to provide the required pressure for the water distribution systems rather than satisfying the water demand. Satisfactory performance of tanks during strong ground motions is crucial for modern facilities. Theoritical and experimental investigations of the dynamic behaviour of liquid storage tanks are conducted to seek possible improvments in the design of such tanks to resist earthquakes. The behaviour and performance of a new elevated tank was studied in this work. It was carried out through finite elements... 

    Application of Endurance Time Method in Nonlinear Dynamic analysis of Elevated Tanks

    , M.Sc. Thesis Sharif University of Technology Rahmati, Mohammad (Author) ; Esmaeil Pourestekanchi, Homayoon (Supervisor)
    Abstract
    Endurance Time (ET) is a fairly comprehensive analytical method based on time history analysis applied for evaluating structural systems excited by dynamic loading of earthquake. In such evaluation assessment measure is based on endurance time of structure versus applied accelerogram function and parameters such as stiffness, lateral resistance, period of vibration and dynamic characteristics are not used directly. In this research nonlinear dynamic analysis of elevated steel tanks with laterally braced framed tower under the loading of earthquake records and ET accelerograms was studied and effectivity of ET method in analyzing such elevated tanks was verified. Due to complication of... 

    Effect of DEM Resolution on Hydraulic Modeling of Flood Inundation Area: Case Study of Gorganrood River, Northeast of Iran

    , M.Sc. Thesis Sharif University of Technology Khojeh, Shokoufeh (Author) ; Ataie Ashtiani, Behzad (Supervisor)
    Abstract
    Digital Elevation Models (DEM) is a crucial element of hydraulic models, including floods. Due to the lack of high-precision topographic data, including ground-based mapping hydraulic modeling is challenging. In recent years, remote sensing data, extensively used by many researchers in hydraulic modeling due to global coverage and free access. One of the most critical questions in hydraulic modeling is the efficiency of these DEMs in flood simulation. This research focused on using remote-sensing-based DEMs, such as SRTM-30m and 90m, ASTER-30m, and ALOS-12.5m DEMs, on the performance of the HEC-RAS-2D model in the Gorganrood river.The results showed that ALOS and SRTM-30m DEMs' accuracy and... 

    Compressive and Bond Behavior of Concrete-Filled Pultruded GFRP and PE Tubes Under Elevated Temperatures

    , Ph.D. Dissertation Sharif University of Technology Tabatabaeian Nimavard, Mojtaba (Author) ; Khaloo, Alireza (Supervisor)
    Abstract
    Concrete-filled GFRP and PE tubes are composite systems using the polymeric tubes as confinement for the marine structures to extend their service life. However, elevated temperatures and thermal cycles in marine environments can affect the behavior of such composite systems. In this investigation, the effect of elevated temperatures and thermal cycles on the performance of concrete-filled pultruded GFRP tubes (CFPGT) and concrete-filled polyethylene tubes (CFPT) is assessed, respectively. For this, different parameters such as concrete core strength (30 and 60 MPa), exposure temperature (25, 100, 200, 300, and 400°C), time exposure (60 and 120 min.), number of thermal cycles (50, 100, and... 

    Multi criteria site selection model for wind-compressed air energy storage power plants in Iran

    , Article Renewable and Sustainable Energy Reviews ; Vol. 32 , April , 2014 , pp. 579-590 ; ISSN: 13640321 Satkin, M ; Noorollahi, Y ; Abbaspour, M ; Yousefi, H ; Sharif University of Technology
    Abstract
    In this research, a site selection method for wind-compressed air energy storage (wind-CAES) power plants was developed and Iran was selected as a case study for modeling. The parameters delineated criteria for potential wind development localities for wind-CAES power plant sites. One important consequence of this research was the identification of the wind energy potential for wind-CAES sites. The theoretical wind energy potential of Iran of greater than 50 W/m2 was identified from a wind atlas of Iran. The model produced factor maps by considering the boundary conditions of the input data and created geo-databases from the outputs maps. The main factor maps were electrical grids and... 

    A data mining approach for diagnosis of coronary artery disease

    , Article Computer Methods and Programs in Biomedicine ; Volume 111, Issue 1 , 2013 , Pages 52-61 ; 01692607 (ISSN) Alizadehsani, R ; Habibi, J ; Hosseini, M. J ; Mashayekhi, H ; Boghrati, R ; Ghandeharioun, A ; Bahadorian, B ; Sani, Z. A ; Sharif University of Technology
    2013
    Abstract
    Cardiovascular diseases are very common and are one of the main reasons of death. Being among the major types of these diseases, correct and in-time diagnosis of coronary artery disease (CAD) is very important. Angiography is the most accurate CAD diagnosis method; however, it has many side effects and is costly. Existing studies have used several features in collecting data from patients, while applying different data mining algorithms to achieve methods with high accuracy and less side effects and costs. In this paper, a dataset called Z-Alizadeh Sani with 303 patients and 54 features, is introduced which utilizes several effective features. Also, a feature creation method is proposed to... 

    Hydroxyapatite nanocomposites: Synthesis, sintering and mechanical properties

    , Article Ceramics International ; Volume 39, Issue 3 , April , 2013 , Pages 2197-2206 ; 02728842 (ISSN) Aminzare, M ; Eskandari, A ; Baroonian, M. H ; Berenov, A ; Razavi Hesabi, Z ; Taheri, M ; Sadrnezhaad, S. K ; Sharif University of Technology
    2013
    Abstract
    Two different hydroxyapatite based composites reinforced by oxide ceramic (20 wt%) nano crystals were synthesized by high-energy ball milling and sintered by pressure less technique. Alumina and titania nanoparticles as secondary phases improved densification and mechanical behavior of apatite and postponed its decomposition to the tricalcium phosphate (TCP) phases at elevated temperatures. Increasing the relative density of apatite using nano reinforcements leads to enhance the bending strength by more than 40% and 27% (as compared to the pure HA) and increase the hardness from 2.52 to 5.12 (Al2O3 composite) and 4.21 (TiO2 addition) GPa, respectively. Transmission electron microscopy (TEM),... 

    Using satellite data to extract volume-area-elevation relationships for Urmia Lake, Iran

    , Article Journal of Great Lakes Research ; Volume 39, Issue 1 , March , 2013 , Pages 90-99 ; 03801330 (ISSN) Sima, S ; Tajrishy, M ; Sharif University of Technology
    2013
    Abstract
    Urmia Lake in the northwest of Iran is the second largest hyper-saline lake worldwide. During the past two decades, a significant water level decline has occurred in the lake. The existing estimations for the lake water balance are widely variable because the lake bathymetry is unknown. The main focus of this study is to extract the volume-area-elevation (V-A-L) characteristics of Urmia Lake utilizing remote sensing data and analytical models. V-A-L equations of the lake were determined using radar altimetry data and their concurrent satellite-derived surface data. Next, two approximate models, a power model (PM) and a truncated pyramid model (TPM), were parameterized for Urmia Lake and... 

    Production of net-shaped dense metal-carbide-based composites through an infiltration process at intermediate temperature

    , Article International Journal of Refractory Metals and Hard Materials ; Volume 38 , 2013 , Pages 35-39 ; 02634368 (ISSN) Davarpanah, A ; Sani, M. A. F ; Shabani, K ; Bodaghi, M ; Sharif University of Technology
    2013
    Abstract
    Tungsten composites are interesting materials for high temperature applications. These composites are conventionally produced by solid state reaction, where elevated temperatures and long sintering processes are inevitable, and generally produce volatile components that increase defects and impair the properties of the composites for high temperature applications. In the present paper, synthesis of dense near net-shaped transition metal-metal carbide by reaction casting is studied, which creates a potential application for the composite at 2000 C. Since the pores of the ceramic preform are filled with reaction products, this technique is referred to as displacive compensation porosity (DCP).... 

    Al-Al3Ti nanocomposite produced in situ by two-step hot-press sintering

    , Article IOP Conference Series: Materials Science and Engineering ; Volume 40, Issue 1 , 2012 ; 17578981 (ISSN) Nikfar, B ; Ghiabakloo, H ; Hosseini, H. R. M ; Mohammadi, A. V ; Sharif University of Technology
    2012
    Abstract
    Aluminum reinforced with a large amount (up to about 55 vol.%) of Al 3Ti particles can be fabricated from Al-20Ti elemental nanometer-sized powder mixture via in-situ two step hot press sintering (TSS). For production of intermetallic reinforced in-situ composite, TSS can provide elevated temperature to facilitate the formation of intermetallic phase in situ and hot consolidation to form a fully dense solid. The first step sintering was employed at a higher temperature to obtain an initial high density, and the second step was held at a lower temperature by isothermal sintering for more time than the first one to increase bulk density without significant grain growth. The optimum TSS regime... 

    Tribological characterization of electroless Ni-10% P coatings at elevated test temperature under dry conditions

    , Article International Journal of Advanced Manufacturing Technology ; Volume 62, Issue 9-12 , October , 2012 , Pages 1063-1070 ; 02683768 (ISSN) Masoumi, F ; Ghasemi, H. R ; Ziaei, A. A ; Shahriari, D ; Sharif University of Technology
    Springer  2012
    Abstract
    An experimental study of wear characteristics of electroless Ni-10% P coating sliding against hard AISI 52100 steel pin is investigated. Experiments are carried out at room and 550°C temperatures. Heat treatment effects on tribological behavior of this coating are studied. The wear surface and the microstructure of the coatings are analyzed using optical microscopy, scanning electron microscopy, energy dispersion analysis X-ray, and microhardness testing equipment. It is observed that the forming of continuous oxide film on contacting surfaces of pin and disk improves wear resistance and decreases friction coefficient of the Ni-10% P coating. The results indicate that the wear resistance of... 

    A trace-time framework for prediction of elevation angle over land mobile LEO satellites networks

    , Article Wireless Personal Communications ; Volume 62, Issue 4 , February , 2012 , Pages 793-804 ; 09296212 (ISSN) Seyedi, Y ; Rahimi, F ; Sharif University of Technology
    2012
    Abstract
    Elevation angle is one of the most significant parameters of land mobile satellite channels, subject to rapid variations in the case of Low Earth Orbit (LEO) satellite systems. In this paper a novel trace-based framework is proposed and analyzed which is capable of predicting elevation angle as a function of time during satellite visibility window. Trace-time based modeling makes the framework practical for real-time evaluation of elevation angle and its alteration incurred by communication links in LEO satellite systems. The proposed method is particularly suitable for development of communication channel models and services in mobile LEO satellite networks where path variability is of... 

    Nonlinear vibrations and chaos in floating roofs

    , Article Journal of Computational and Nonlinear Dynamics ; Volume 7, Issue 2 , January , 2012 ; 15551415 (ISSN) Shabani, R ; Tariverdilo, S ; Salarieh, H ; Sharif University of Technology
    2012
    Abstract
    Variational principle is used to derive the nonlinear response of the floating roof of cylindrical liquid storage tanks due to harmonic base excitations. The formulation accounts for nonlinearity due to large deflections of the floating roof. The derived nonlinear governing equation for the sloshing response of the floating roof has a cubic nonlinear stiffness term similar to the well known Duffing equation. It is shown that accounting for large deflections could substantially reduce the wave elevation for near resonance harmonic excitations. Evaluating the response of the nonlinear model for increasing amplitudes of near resonance harmonic excitations gives rise to the appearance of sub and... 

    Nano reengineering of horseradish peroxidase with dendritic macromolecules for stability enhancement

    , Article Enzyme and Microbial Technology ; Volume 50, Issue 1 , 2012 , Pages 10-16 ; 01410229 (ISSN) Khosravi, A ; Vossoughi, M ; Shahrokhian, S ; Alemzadeh, I ; Sharif University of Technology
    Abstract
    A simple bio-conjugation procedure to surround a single horseradish peroxidase (HRP) enzyme molecule with dendritic polyester macromolecules (polyester-32-hydroxyl-1-carboxyl bis-MPA dendron, generation 5) was proposed. The characterization of resultant nanoparticles entitled HRP dendrozyme, was performed by transmission electron microscopy, dynamic light scattering, gel permeation chromatography and Fourier transform infrared spectroscopy. The results showed that HRP nanoparticles were spherical in shape and have an average size of 14 ± 2. nm in diameter. Furthermore, bio-conformational characterization of HRP dendrozyme was performed by means of circular dichroism and fluorescence... 

    Near-optimal terrain collision avoidance trajectories using elevation maps

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 47, Issue 4 , October , 2011 , Pages 2490-2501 ; 00189251 (ISSN) Malaek, S. M ; Abbasi, A ; Sharif University of Technology
    2011
    Abstract
    The main attempt of this paper is to present a new methodology to model a generic low-level flight close to terrain, which guarantees terrain collision avoidance. Benefiting the advantages of high-speed computer technology, this method uses satellite elevation maps to generate so-called "quad-tree forms". The latter is then used to find the optimal trajectories for low-level flights. The novelty of this approach, entitled the "cost map," lies in the integration of aircraft dynamics into the segmented map. This procedure results in some near-optimal trajectories with respect to aircraft dynamics that could easily be used for minimization of flight path together with pilot effort. Different... 

    A simple granulation technique for preparing high-porosity nano copper oxide(II) catalyst beads

    , Article Particuology ; Volume 9, Issue 5 , 2011 , Pages 480-485 ; 16742001 (ISSN) Ahmadi, S. J ; Outokesh, M ; Hosseinpour, M ; Mousavand, T ; Sharif University of Technology
    Abstract
    A simple and efficient method was developed for fabricating spherical granules of CuO catalyst via a three-step procedure. In the first step, copper oxide nanoparticles were synthesized by hydrothermal decomposition of copper nitrate solution under supercritical condition. Then, they were immobilized in the polymeric matrix of calcium alginate, and followed by high-temperature calcination in an air stream as the third step, in which carbonaceous materials were oxidized, to result in a pebble-type catalyst of high porosity. The produced CuO nanoparticles were characterized by transmission electron microscopy (TEM) that revealed an average size of 5 nm, X-ray diffractometry (XRD), and thermo... 

    Constitutive modeling of temperature and strain rate dependent elastoplastic hardening materials using a corotational rate associated with the plastic deformation

    , Article International Journal of Plasticity ; Volume 27, Issue 9 , 2011 , Pages 1445-1455 ; 07496419 (ISSN) Ghavam, K ; Naghdabadi, R ; Sharif University of Technology
    Abstract
    In this paper, a constitutive model with a temperature and strain rate dependent flow stress (Bergstrom hardening rule) and modified Armstrong-Frederick kinematic evolution equation for elastoplastic hardening materials is introduced. Based on the multiplicative decomposition of the deformation gradient,new kinematic relations for the elastic and plastic left stretch tensors as well as the plastic deformation-dependent spin tensor are proposed. Also, a closed-form solution has been obtained for the elastic and plastic left stretch tensors for the simple shear problem.To evaluate model validity, results are compared with known experimental data for SUS 304 stainless steel, which shows a good... 

    Phase formation during sintering of nanocrystalline zirconia/stainless steel functionally graded composite layers

    , Article Materials Letters ; Volume 65, Issue 3 , February , 2011 , Pages 523-526 ; 0167577X (ISSN) Dourandish, M ; Simchi, A ; Hokamoto, K ; Tanaka, S ; Sharif University of Technology
    Abstract
    Microstructural development and phase formation at the interface of yttria stabilized zirconia (3Y-TZP)/430L stainless steel composite layers produced by co-sintering method were studied by SEM, HRTEM, micro-focus XRD, and EPMA. Formation of a rich chromium boundary layer at the interface was noticed, which revealed Cr aggregation at the interface at the elevated temperatures. Misfit dislocations were also observed at the joint interface to tackle the mismatch crystallographic orientations between the ceramic and metal layer. The results of the micro-focus XRD showed formation of no new phases at the boundary zone. Microstructural studies also revealed a retarded grain growth in the...