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    Power Reduction Through Efficient Serial Transmission in NoCs

    , M.Sc. Thesis Sharif University of Technology Bonakdar, Hojjat (Author) ; Hessabi, Shahin (Supervisor)
    Abstract
    With progress in integrated circuits technology, on chip systems have become operational, and after that, onchip network are as solutions to improve onchip connections and also its scalability. With improving technology, the number of cores on chips can be more, that it causes increasing importance of produced problems by parallel links. Serial links are one of the methods to decrease these problems. Serial links have some advantages in compare with parallel links in some aspects like: clock pulse skew, cross talk, area cost, difficulties in wiring and synchronizing clock pulse signals. But any way, problems such as high operational frequency and complicated serializer and deserializer... 

    Flight envelope expansion in landing phase using classic, intelligent and adaptive controllers [electronic resource]

    , Article Journal of aircraft ; 2006, Vol. 43, No. 1 Malaek .S. M. B ; Izadi, Hojjat Allah ; Pakme, Mehrdad
    Abstract
    An expanding flight envelope in the landing phase of a typical jet transport aircraft in presence of strong wind shears using a learning capable control system (LCCS) is investigated. The idea stems fromhuman beings functional architecture that gives them the ability to do more as they age and gain more experience. With the knowledge that classical controllers lack sufficient generality to cope with nonlinear as well as uncertain phenomenon such as turbulent air, the focuse is on different types of intelligent controllers due to their learning and nonlinear generalization capabilities as candidates for the landing flight phase. It is shown that the latter class of controllers could be used... 

    Mind-Body Problem from Wittgenstein’s Perspective

    , M.Sc. Thesis Sharif University of Technology Karimi, Ahmad (Author) ; Hojjat, Mino (Supervisor)
    Abstract
    To provide a stable foundation for human knowledge Descartes presumed that human being is composed of two distinct substances, the mind and the body. But, the solution through which he wanted to explain the correlation between these substances, was not accepted by other philosophers, and thereafter this problem was known as mind-body problem. This problem arises some other philosophical problems including solipsism and the problem of other minds. In this thesis, considering the grammar of such words like memory, understanding, and thinking I will show that having an exact description of these concepts we would be able to escape from these inclination to seek something behind these words, and... 

    Designing a System for Pulse Pile-Up Processing in Gamma Ray Spectroscopy Based on Digital Method

    , M.Sc. Thesis Sharif University of Technology Hojjat, Saeed (Author) ; Hosseini, Abolfazl (Supervisor)
    Abstract
    In Radiation Detection Systems applied in Spectroscopy and Imaging, if the rate of particle incidence with detector is high, the output pulses being stacked up on each other will be expected, which is known as “Pulse Pile-up”. Pulse pile-up might result in a serious disorder of energy and timing data expected from the pulses. In recent decades and after successful implementation of pile-up rejection methods on analog circuits, considering development and progression in the field of digital, different algorithms based on pileup correction methods have been developed to obtain all spectrum information, whether energy, rise time and recorded pulses. Such methods can be compared in different... 

    Effect of centrifugal force on frequency characteristic of rotating hollow cylinders using a newly designed cylindrical super element

    , Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 10716947 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) Bonakdar, M ; Ahmadian, M. T ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2006
    Abstract
    A sixteen node cylindrical super element is presented for evaluating the free vibration characteristics of a rotating laminated cylinder with conventional boundary conditions. It is shown that the natural frequencies are affected considerably when the centrifugal force is also taken into account. The vibration frequencies of rotating finite cylinder, obtained by conventional finite element are used to evaluate the accuracy of this approach. The special case of a stationary cylinder with zero spinning velocity is also considered as a check on this method. Results indicate only few number of cylindrical super elements are capable of predicting the natural frequency of the rotating cylinder... 

    Fabrication and Characterization of a Hydrogel Absorbent for the Simultaneous Removal of Dye and Heavy Ion Metal From Water

    , M.Sc. Thesis Sharif University of Technology Ahmadi Bonakdar, Arezoo (Author) ; Pircheraghi, Gholamreza (Supervisor)
    Abstract
    In recent years, environmental concerns regarding the removal of pollutants such as organic dyes and heavy metals from water sources have increased significantly. In this regard, hydrogels based on natural polymers have attracted considerable attention for water treatment applications due to their biodegradability, low toxicity, and desirable stability. Hydrogel beads, with their highly porous structure, provide high adsorption capacity and rapid adsorption kinetics. In this study, hydrogel beads based on alginate and polyvinyl alcohol (PVA) polymers were fabricated as mixed and hybrid composites in the presence of zeolitic imidazolate framework (ZIF-8) and diatomite fillers. For this... 

    Integrating module checking and deduction in a formal proof for the perlman Spanning Tree Protocol (STP)

    , Article Journal of Universal Computer Science ; Volume 13, Issue 13 , 2007 , Pages 2076-2104 ; 0958695X (ISSN) Hojjat, H ; Nakhost, H ; Sirjani, M ; Sharif University of Technology
    2007
    Abstract
    In the IEEE 802.1D standard for the Media Access Control layer (MAC layer) bridges, there is an STP (Spanning Tree Protocol) definition, based on the algorithm that was proposed by Radia Perlman. In this paper, we give a formal proof for correctness of the STP algorithm by showing that finally a single node is selected as the root of the tree and the loops are eliminated correctly. We use formal inductive reasoning to establish these requirements. In order to ensure that the bridges behave correctly regardless of the topology of the surrounding bridges and LANs, the Rebeca, modular verification techniques are applied. These techniques are shown to be efficiently applicable in model checking... 

    Application of a new cylindrical element formulation in finite element structural analysis of FGM hollow cylinders

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 14 , 2009 , Pages 21-25 ; 9780791848753 (ISBN) Ahmadian, M. T ; Taghvaeipour, A ; Bonakdar, M ; Sharif University of Technology
    2009
    Abstract
    Functionally graded materials are advanced composite materials consisting two or more material ingredients that are engineered to have a continuous spatial variation of properties. There are a few analytical methods available to solve the governing equations of FGM made structures, confined to some specific and limited shapes, loadings and boundary conditions. Hence the numerical methods such as FEM are used to treat these materials. In previous studies the finite element method was used to solve thin walled FG structures like shells and plates by modification of the conventional shell and plate elements. Solving the thick walled FG structures confronts some difficulties. One of the methods... 

    Optimal active control of vehicle suspension system including time delay and preview for rough roads

    , Article JVC/Journal of Vibration and Control ; Volume 8, Issue 7 , 2002 , Pages 967-991 ; 10775463 (ISSN) Marzbanrad, J ; Ahmardi, G ; Hojjat, Y ; Zohoor, H ; Sharif University of Technology
    SAGE Publications Inc  2002
    Abstract
    An optimal preview control of a vehicle suspension system traveling on a rough road is studied. A three-dimensional seven degree-of-freedom car-riding model and several descriptions of the road surface roughness heights, including haversine (hole/bump) and stochastic filtered white noise models, are used in the analysis. It is assumed that contact-less sensors affixed to the vehicle front bumper measure the road surface height at some distances in the front of the car. The suspension systems are optimized with respect to ride comfort and road holding preferences including accelerations of the sprung mass, tire deflection, suspension rattle space and control force. The performance and power... 

    Stochastic optimal preview control of a vehicle suspension

    , Article Journal of Sound and Vibration ; Volume 275, Issue 3-5 , 2004 , Pages 973-990 ; 0022460X (ISSN) Marzbanrad, J ; Ahmadi, G ; Zohoor, H ; Hojjat, Y ; Sharif University of Technology
    Academic Press  2004
    Abstract
    Stochastic optimal control of a vehicle suspension on a random road is studied. The road roughness height is modelled as a filtered white noise stochastic process and a four-degree-of-freedom half-car model is used in the analysis. It is assumed that a sensor is mounted in the front bumper that measures the road irregularity at some distances in the front of the vehicle. Two other sensors also measure relative velocities of the vehicle body with respect to the unsprung masses in the vehicle suspension spaces. All measurements are assumed to be conducted in a noisy environment. The state variables of the vehicle system are estimated using a method similar to the Kalman filter. The suspension... 

    Smart antennas for OFDM-WLANs based on a spatial-temporal multi-scenario channel model

    , Article Iranian Journal of Electrical and Computer Engineering ; Volume 7, Issue 2 , 2008 , Pages 107-114 ; 16820053 (ISSN) Alihemmati, R ; Dadashzadeh, G ; Shishegar, A. A ; Hojjat, N ; Sharif University of Technology
    Jahad Daneshgahi  2008
    Abstract
    combination of smart antenna techniques and OFDM could be considered as a promising solution for improving the performance and enhancing the data rates of next generation wireless communication systems operating in frequency selective fading environments. There are different design parameters which could affect the application of adaptive arrays in OFDM-based systems. Various beam-forming methods in frequency or time domain, different array architectures and various number of array elements are important factors which are able to change the performance and complexity of the system. These parameters may show different effects in different channel conditions. In this paper we implemented a new... 

    Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 66, Issue 3 , 2017 , Pages 105-114 ; 00914037 (ISSN) Nojoomi, A ; Tamjid, E ; Simchi, A ; Bonakdar, S ; Stroeve, P ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Abstract
    In this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100–250 µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the... 

    A microfabricated platform for the study of chondrogenesis under different compressive loads

    , Article Journal of the Mechanical Behavior of Biomedical Materials ; Volume 78 , 2018 , Pages 404-413 ; 17516161 (ISSN) Kowsari Esfahan, R ; Jahanbakhsh, A ; Saidi, M. S ; Bonakdar, S ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    Microfluidic devices are beneficial in miniaturizing and multiplexing various cellular assays in a single platform. Chondrogenesis is known to pertain to chemical, topographical, and mechanical cues in the microenvironment. Mechanical cues themselves have numerous parameters such as strain magnitude, frequency, and stimulation time. Effects of different strain magnitudes on the chondrogenic differentiation of adult stem cells have not been explored thoroughly. Here, a new multilayer microdevice is presented for the unidirectional compressive stimulation of cells in a three-dimensional cell culture. Numerical simulations were performed to evaluate and optimize the design. Results showed a... 

    Partial order reduction for timed actors

    , Article 13th International Conference on Verified Software: Theories, Tools, and Experiments, VSTTE 2021 and 14th International Workshop on Numerical Software Verification, NSV 2021, 18 October 2021 through 19 October 2021 ; Volume 13124 LNCS , 2022 , Pages 43-60 ; 03029743 (ISSN); 9783030955601 (ISBN) Bagheri, M ; Sirjani, M ; Khamespanah, E ; Hojjat, H ; Movaghar, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    We propose a compositional approach for the Partial Order Reduction (POR) in the state space generation of asynchronous timed actors. We define the concept of independent actors as the actors that do not send messages to a common actor. The approach avoids exploring unnecessary interleaving of executions of independent actors. It performs on a component-based model where actors from different components, except for the actors on borders, are independent. To alleviate the effect of the cross-border messages, we enforce a delay condition, ensuring that an actor introduces a delay in its execution before sending a message across the border of its component. Within each time unit, our technique... 

    A Model for Logistics Management in Natural Disaster Relief

    , M.Sc. Thesis Sharif University of Technology Hojjat Panah, Sharareh (Author) ; Eshghi, Kourosh (Supervisor) ; Najafi, Mehdi (Co-Advisor)
    Abstract
    Research and information available shows that the number of natural disasters are increasing dramatically; hence disaster management is being raised as one of the most important topics in this field. The relief logistics is the greater part of disaster management model.
    In this study, in order to manage the logistics activities effectively in a response phase of an earthquake, a hybrid meta-heuristic algorithm is developed for a transportation network. Then, the proposed algorithm is tested on a small part of Tehran.
     

    Fabrication of biocompatible titanium scaffolds using space holder technique

    , Article Journal of Materials Science: Materials in Medicine ; Volume 23, Issue 10 , 2012 , Pages 2483-2488 ; 09574530 (ISSN) Dezfuli, S. N ; Sadrnezhaad, S. K ; Shokrgozar, M. A ; Bonakdar, S ; Sharif University of Technology
    Springer  2012
    Abstract
    Open-pore titanium scaffolds were fabricated by sintering of compressed mixtures of TiH1.924 and urea. Spherical and irregular shaped space holders were used to investigate the effect of pore shape on cellular behavior. After removal of the space holder, the shape of the spacers was replicated to the pores. Average diameter of the pores was in the range of 300-600 lm. SEM images showed that titanium hydride resulted in higher surface roughness and larger micro porosities than pure titanium. In vitro evaluationswere carried out by using MTT assay, measuring alkaline phosphatase activity and alizarin red staining in flow perfusion bioreactor for cell culture. Observations revealed excellent... 

    Hybrid cross-linked hydrogels based on fibrous protein/block copolymers and layered silicate nanoparticles: Tunable thermosensitivity, biodegradability and mechanical durability

    , Article RSC Advances ; Volume 6, Issue 67 , 2016 , Pages 62944-62957 ; 20462069 (ISSN) Eslahi, N ; Simchi, A ; Mehrjoo, M ; Shokrgozar, M. A ; Bonakdar, S ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Abstract
    Stimuli responsive polymer hydrogels have sparked a considerable interest for biomedical applications. In this work, we present a novel injectable thermal responsive hydrogel based on mineral nanoclay (LAPONITE®), wool-derived fibrous protein (keratin), triblock copolymer (Pluronic), and chitosan biopolymer with potential applications for articular cartilage tissue engineering. Genipin was utilized as a natural crosslinker. The formation of polymer conjugates between the components is confirmed by FTIR and 1H NMR spectroscopy. The nanocomposite hydrogel contains interconnected pores within the hydrogel network and the size of the pores is found to reduce at higher crosslinking density and on... 

    , M.Sc. Thesis Sharif University of Technology Bonakdar Shirazi, Ashkan (Author) ; Alavi, Babak (Supervisor) ; Feyzbakhsh, Alireza (Supervisor)
    Abstract
    Entrepreneurship is a process that requires high motivation for success. Self-efficacy is to believe the person's ability to organize and carry out certain types of activities to produce specific outcomes. Thus helping to increase self-efficacy beliefs in people who have attempted to entrepreneurship can increase their chances of success. On the other hand Self-leadership has been defined as “the process” of influencing oneself to establish the self-direction and self-motivation needed to perform. And include three major strategies named Behavioral focused strategies, Intrinsic motivation (Natural Reward) strategies, Constructive thought pattern strategies and some specific behaviors in each... 

    Comparison of the smart antenna architectures for OFDM-WLAN systems in a rich multipath environment based on a spatio-temporal channel model

    , Article 2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2005, Berlin, 11 September 2005 through 14 September 2005 ; Volume 1 , 2005 , Pages 97-101 ; 3800729091 (ISBN); 9783800729098 (ISBN) Alihemmati, R ; Shishegar, A. A ; Hojjat, N ; Dadashzadeh, G ; Boghrati, B ; Mehrtash, A ; Sharif University of Technology
    2005
    Abstract
    The smart antenna technique as a method of improving the physical layer performance of OFDM WLANs is studied. For this purpose, a comparison of the smart antenna architectures for IEEE802.11a WLAN system using pre-FFT and post-FFT array processing with different parameters is represented. Simulations are performed on a new Simulink model for IEEE802.11a system using a spatio-temporal channel modeling which is based on the measured wideband channels in the 5GHz band. Raw bit-error-rate performance for QPSK/16QAM modulations at LOS and NLOS channel scenarios are evaluated and compared. © 2005 IEEE  

    Gas sweetening process optimization with economic, Exergy and Environmental criteria

    , M.Sc. Thesis Sharif University of Technology Ehsani, Hojjat Allah (Author) ; Farhadi, Fathollah (Supervisor) ; Bozorg Mehri, Ramin (Supervisor)
    Abstract
    In the present work, a comprehensive economic, environmental and exergy analysis and multi-objective optimization for gas sweetening plant are provided and the interaction between decision variables in these criterions is discussed. In the first part, potentials of three environmental features (global warming, acid rain, smog formation) of the operational plant are quantified and normalized using life cycle assessment (LCA) for both process waste and utility environmental impacts.Acid rain index is determined as the most important environmental impactindex in this unit. By choosing proper decision variables based on sensitivity analysis, LCA and EA results, optimization is performed to...