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    Investigation of concrete beam behavior in FRP composite layering under incremental loading

    , Article International Journal of Applied Engineering Research ; Volume 11, Issue 4 , 2016 , Pages 2429-2435 ; 09734562 (ISSN) Zarringol, M ; Zarringol, M ; Sharif University of Technology
    Research India Publications  2016
    In this paper, we investigate concrete beam behavior in FRP composite layering under incremental loading. In doing so, we examined four beams with cross section of 200 mm, height of 150 mm and length of 2300 mm. Of these four beams, three were strengthened by FRP sheets with various layer numbers and one was set as the benchmark. The laboratorial samples of the second series were beams with cross section of 150 mm, height of 200 mm and length of 2000 mm. We strengthened the samples by CFRP sheets with various widths and layer numbers and set the other two as benchmark. We examined the standard cylindrical samples and the strengthened and control beams under incremental loading. For this... 

    A method to calculate the linear load pay back factors for air conditioners

    , Article Asia-Pacific Power and Energy Engineering Conference, APPEEC ; 2012 ; 21574839 (ISSN) ; 9781457705472 (ISBN) Ziaii, M ; Kazemi, A ; Fotuhi Firuzabad, M ; Parvania, M ; Sharif University of Technology
    Load pay back effect is the excess of load as a result of load curtailment, observed in direct load control programs related to thermostatically controlled appliances. In this paper, according to a stochastic difference equation, the load profile of an aggregation of customers without control will be attained. Then the assumption to consider load pay back as linear will be examined through simulations. Afterwards, based on a data structure gained from performing load curtailments at each interval, least-square method will be used to fit load pay back factors for each interval. It is notable that there are some significant differences between the results attained in this paper and what was... 

    Intelligent topology-oriented load shedding scheme in power systems

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 652-656 ; 9781728115085 (ISBN) Zare, F ; Ranjbar, A ; Faghihi, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Load shedding is a prevalent emergency control designed to prevent system blackouts. The higher complexity and lower predictability of modern power systems makes it difficult to rely on conventional load shedding schemes which shed loads in pre-defined steps without sufficient consideration of the actual system characteristics and the disturbance situations. In case of large disturbances, the power system stability can be improved by optimal load shedding in more effective load buses. Proposed scheme utilizes improved Power Flow Tracing method to determine the amount and location of load drops considering power system constraints. Numerical simulations conducted on IEEE 39 bus standard test... 

    Axisymmetric thermo-electro-elastic analysis of a piezoelectric half space

    , Article Mathematics and Mechanics of Solids ; Volume 17, Issue 5 , September , 2012 , Pages 500-515 ; 10812865 (ISSN) Kargarnovin, M. H ; Hashemi, R ; Hashemi, M ; Sadeghi, H ; Sharif University of Technology
    In this study, an analytical solution is presented for thermo-electro- elastic analysis of piezoelectric semi-infinite bodies. For this purpose, governing equations are derived for a transversely isotropic piezoelectric material under an axisymmetric thermo-electro-mechanical loading condition. A general closed-form analytical solution is presented for the complementary and particular parts of the components of the displacement vector and also for the electric potential function. Then, boundary conditions are imposed and in that case an explicit solution is obtained for piezoelectric semi-infinite bodies. Results show that when a piezoelectric half space is subjected to constant/ramp surface... 

    Game theoretic based charging strategy for plug-in hybrid electric vehicles

    , Article IEEE Transactions on Smart Grid ; Vol. 5,Issue. 5 , 2014 , pp. 2368-2375 ; ISSN: 19493053 Bahrami, S ; Parniani, M ; Sharif University of Technology
    In the future smart grids, Plug-in Hybrid Electric Vehicles (PHEVs) are seen as an important means of transportation to reduce greenhouse gas emissions. One of the main issues regarding to this sort of vehicles is managing their charging time to prevent high peak loads over time. Deploying advanced metering and automatic chargers can be a practical way not only for the vehicle owners to manage their energy consumption, but also for the utilities to manage the electricity load during the day by shifting the charging loads to the off-peak periods. Additionally, an efficient charging schedule can reduce the users' electricity bill cost. In this paper we propose a new practical demand response... 

    Optimization of synthetic conditions CMC-g-poly (acrylic acid)/celite composite superabsorbent by taguchi method and determination of its absorbency under load

    , Article Express Polymer Letters ; Volume 1, Issue 8 , 2007 , Pages 488-494 ; 1788618X (ISSN) Pourjavadi, A ; Amini Fazl, M. S ; Ayyari, M ; Sharif University of Technology
    A novel biopolymer-based composite hydrogel was synthesized through chemical crosslinking by graft copolymerization of partially neutralized acrylic acid onto the carboxymethyl cellulose (CMC). The Taguchi method, a robust experimental design, was employed for the optimization of the synthesis based on the swelling capacity of the hydrogels. This method was applied for the experiments and standard L16 orthogonal array with five factors and four levels. In the synthesis of the composite superabsorbent, N,N'-methylene bisacrylamide (MBA) as crosslinker, ammonium persulfate (APS) as initiator, acrylic acid (AA) as monomer, CMC/Celite weight ratio and neutralization percent (NU) were used as... 

    Molecular dynamics investigation of β-SiC behavior under three-axial tensile loading [electronic resource]

    , Article Journal of Computational and Theoretical Nanoscience ; November 2011, Volume 8, Number 11, PP. 2187-2192 Mortazavi, B ; Simchi, A. (Abdolreza) ; Besharati-Givi, M.K ; Rajabpour, A ; Sharif University of Technology
    Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress–strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress–strain relationship. The MD... 

    Effect of cyclic loading on the temporomandibular joint

    , Article Lecture Notes in Engineering and Computer Science ; Volume 1 , 2014 , Pages 655-658 ; ISSN: 20780958 ; ISBN: 9789881925275 Muhandiram, J ; Wang, B ; Chizari, M ; Sharif University of Technology
    This research is aiming to investigate the mechanical behaviour of the temporomandibular joint (TMJ), in response to kinematics/cyclical loading caused through actions of speech and mastication. A set of in-vitro experimental tests has been performed in three different groups on a fresh sheep jaw bone to examine the hypothesis of the study. No failure was monitored during the cyclical test. The study was concluded that the amount of loading is effective on the displacement of the TMJ  

    Can simple trunk muscle models balance and stabilize lumbar spine during support of symmetric and asymmetric loads? a FE model study

    , Article 2007 ASME Summer Bioengineering Conference, SBC 2007, Keystone, CO, 20 June 2007 through 24 June 2007 ; 2007 , Pages 443-444 ; 0791847985 (ISBN); 9780791847985 (ISBN) Kiapour, A ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology

    Surface waves on a half-space due to a time-harmonic loading on an inertial strip foundation

    , Article Journal of Vibration and Acoustics, Transactions of the ASME ; Volume 135, Issue 5 , 2013 ; 10489002 (ISSN) Dehestani, M ; Vafai, A ; Choobbasti, A. J ; Malidarreh, N. R ; Szidarovszky, F ; Sharif University of Technology
    An analytical approach has been applied to obtain the solution of Navier's equation for a homogeneous, isotropic half-space under an inertial foundation subjected to a timeharmonic loading. Displacement potentials were used to change the Navier's equation to a system of wave-type equations. Calculus of variation was employed to demonstrate the contribution of the foundation's inertial effects as boundary conditions. Use of the Fourier transformation method for the system of Poisson-type equations and applying the boundary conditions yielded the transformed surface displacement field. Direct contour integration has been employed to achieve the surface waves. In order to clarify the... 

    On low back pain: Identification of structural changes in system parameters for fatigue loaded intervertebral disc using PCA

    , Article ICIAS 2012 - 2012 4th International Conference on Intelligent and Advanced Systems: A Conference of World Engineering, Science and Technology Congress (ESTCON) - Conference Proceedings, 12 June 2012 through 14 June 2012 ; Volume 1 , June , 2012 , Pages 378-381 ; 9781457719677 (ISBN) Khan, M. F ; Malik, A. S ; Rozana, F ; Xia, L ; Nikkhoo, M ; Wang, J. L ; Parnianpour, M ; Sharif University of Technology
    This paper presents the background of low back problem caused by repetitive fatigue loading. We emphasize on mechanism of Intervertebral Disc (IVD) and conditions for which the disc does not recover its original status under repetitive work and cause low back pain. The objective of this study is to identify structural changes in system parameters for fatigue loaded intervertebral disc. Principal component analysis (PCA) is used for studying the behavioral change of spine against cyclic loading as a function of time. Percentage difference and similarity factor was calculated for the analysis. Specimens were applied with impulse testing to measure the stiffness and acceleration after fracture,... 

    Effects of concurrent earthquake and temperature loadings on cable-stayed bridges

    , Article International Journal of Structural Stability and Dynamics ; Volume 16, Issue 6 , 2016 ; 02194554 (ISSN) Maleki, S ; Maghsoudi Barmi, A ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd 
    This paper discusses the necessity of considering the concurrent effects of uniform temperature and earthquake loadings in the design of cable-stayed bridges. This load combination is not foreseen in current design standards such as AASHTO and Eurocode. Three-dimensional finite element models of cable-stayed bridges are employed for nonlinear time history analyses. A load combination is proposed that adds uniform temperature loading to the existing extreme event load combination. The proposed combination is compared with existing extreme event load combination and the changes in forces and displacements are noted. A parametric study is then conducted by varying a number of properties of the... 

    A topology-aware load balancing algorithm for P2P systems

    , Article 4th International Conference on Digital Information Management, ICDIM 200916 December 2009 ; 2009 , Pages 97-102 ; 9781424442539 (ISBN) Mirrezaei, S. I ; Shahparian, J ; Ghodsi, M ; Sharif University of Technology
    One of the challenges of P2P systems is to perform load balancing efficiently. A distributed hash table (DHT) abstraction, heterogeneous nodes, and non uniform distribution of objects cause load imbalance in structured P2P overlay networks. Several solutions are suggested to solve this problem but they have some restrictions. They assume the homogeneous capabilities of nodes, unawareness of the link latency during transferring load and imposing logical structures to collect and reassign load. This paper presents a distributed load balancing algorithm with topology awareness using the concept of virtual servers. In our proposed approach, each node collects neighborhood load information from... 

    Influence of load history on the force-displacement response of in-plane loaded unreinforced masonry walls

    , Article Engineering Structures ; Volume 152 , 2017 , Pages 671-682 ; 01410296 (ISSN) Valentin Wilding, B ; Dolatshahi, K. M ; Beyer, K ; Sharif University of Technology
    Empirical drift capacity models for in-plane loaded unreinforced masonry (URM) walls are derived from results of quasi-static cyclic shear-compression tests. The experimentally determined drift capacities are, however, dependent on the applied demand, i.e., on the loading protocol that is used in the test. These loading protocols differ between test campaigns. The loading protocols applied in tests are also different from the displacement histories to which URM walls are subjected in real earthquakes. In the absence of experimental studies on the effect of loading histories on the wall response, this article presents numerical simulations of modern unreinforced clay block masonry walls that... 

    Design of a Novel Loading Mechanism for in Vitro Spine Testing

    , M.Sc. Thesis Sharif University of Technology Sharif, Mohammad Reza (Author) ; Parnianpour, Mohamad (Supervisor) ; Narimani, Roya (Co-Advisor)
    In this project, we use a novel mechanism to control the lumbar rotational profile and also the disc pressure of L3/L4 and L4/L5. Spine, as one of the most important parts of human musculoskeletal system, helps human beings to walk on two feet without much energy consumption. Any problem in this part may cause moving disorders or pain. To heal severe spine disorders, many different methods like surgery and implantation are adopted. To be sure of proper functionality in the human body, these methods should be tested clinically in advance. Cadaver spine testing in vitro, is accepted as a gold standard to evaluate new methods. One of the main challenges facing spine in vitro tests is how to... 

    Fatigue loaded intervertebral disc analysis for low back pain using nonlinear black-box model

    , Article IFMBE Proceedings ; Volume 39 , 2013 , Pages 513-517 ; 16800737 (ISSN) ; 9783642293047 (ISBN) Khan, M. F ; Malik, A. S ; Xia, L ; Nikkhoo, M ; Wang, J. L ; Parnianpour, M ; Humayun, J ; Sharif University of Technology
    This paper presents recent developments on effects of rest and fatigue loading on properties of healthy vertebra discs. A comparison of different approaches used in literature to study the properties of intervertebral disc is presented. The major achievements in this area so far are discussed in the context of their advantages and disadvantages. The past approaches are based on bio-mechanical models which mostly used statistical techniques for the analysis and estimation of fatigue loaded Intervertebral Disc (IVD). However, those modeling techniques were not flexible enough for analysis of customized tests. In this paper, we applied System Identification (SI) based NLARX modeling technique... 

    An analytical approach to obtain optimum load impedance using X-parameters®

    , Article 2012 Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, INMMIC 2012 ; 2012 ; 9781467329491 (ISBN) Zargar, H ; Banai, A ; Cai, J ; Brazil, T ; Sharif University of Technology
    This paper introduces an analytical approach to obtain fundamental and harmonic load-pull contours using X-parameters. This method is proposed to obtain the optimum load impedance at different harmonics. This approach has been applied on a two port X-parameter model and its results are independently verified by ADS simulation  

    Calculation of the deterministic optimum loading pattern of the BUSHEHR VVER-1000 reactor using the weighting factor method

    , Article Annals of Nuclear Energy ; Volume 49 , 2012 , Pages 170-181 ; 03064549 (ISSN) Rahmani, Y ; Pazirandeh, A ; Ghofrani, M. B ; Sadighi, M ; Sharif University of Technology
    In the calculation of the optimum loading pattern for a nuclear reactor, several parameters, including the multiplication factor maximization, the raising of the desired safety threshold during the cycle length and the flattening of the radial power peaking factor should be taken into account. Our evaluation of numerous probable arrangements within the VVER-1000 reactor core (approx. 6 × 10 14 cases) indicated that a direct search of the optimum loading pattern is not feasible. Hence, in this study, the weighting factor method and some constraints on the arrangement of the fuel assemblies were applied so that the above cases were reduced to only 244 possible arrangements. Then, using a... 

    Modeling fatigue behavior of quasi-isotropic laminates

    , Article Procedia Engineering, 5 June 2011 through 9 June 2011 ; Volume 10 , June , 2011 , Pages 3764-3768 ; 18777058 (ISSN) Razavi Hesabi, Z ; Kouchi, A ; Tadi Beni, Y ; Abadyan, M ; Sharif University of Technology
    Fatigue behavior of quasi-isotropic carbon/epoxy laminates were studied, using six stacking sequences. Experimental results show that there is a significant stacking sequence effect on monotonic and cyclic performance of laminates. Though by changing the stacking sequence the difference between failure strength of the strongest and weakest lay-ups reaches only to ∼ 12 %, the difference between fatigue lives (cycles to failure) increased ∼ 1000% in some loading regions. In addition, both linear and sigmoidal functions were examined to model the fatigue life behavior  

    Residential loads modeling by norton equivalent model of household loads

    , Article Asia-Pacific Power and Energy Engineering Conference, APPEEC ; 2011 ; 21574839 (ISSN) ; 9781424462551 (ISBN) Ghorbani, M. J ; Rad, M. S ; Mokhtari, H ; Honarmand, M. E ; Youhannaie, M ; Sharif University of Technology
    These days the number of nonlinear loads in power systems is increasing dramatically. These nonlinear loads inject harmonic currents and the voltages. Accordingly, the modeling of these loads and analysis of their effects on power quality has gained much attention. This paper presents harmonic models for residential appliances. The model is based on Norton equivalent technique. The parameters of appliances models are determined using measurements. These models are then verified by comparison with the measurements results for each load. Based on the developed individual loads, an estimate for a household/an office customer is found and the harmonic content for such customers is estimated. An...