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    Analyzing the Effect of Interconnection Topology on the Performance of Enterprise SSDs

    , M.Sc. Thesis Sharif University of Technology Soltani, Behnaz (Author) ; Sarbazi-Azad, Hamid (Supervisor) ; Hesabi, Shahin (Co-Advisor)
    Abstract
    In recent years, flash-based Solid State Drives (SSDs), because of their lower power consumption, higher throughput, and resistance against physical damages compared to Hard Disk Drives (HDDs) have confronted ever increasing usage in data center, cloud applications, and enterprise servers. Recently, advantages of using interconnection networks between SSD controller and NAND Flash chips for transferring data and commands have been shown. Interconnection network intrinsically provides many advantages such as maintaining the signal integrity at high frequencies, pipelining support, sharing the communication resources, eliminating communication bottlenecks, and reducing power consumption. The... 

    Pinch Analysis of Heat Exchanger Networks in the Crude Oil Distillation Unit of Bandar-Abbas Refinery

    , M.Sc. Thesis Sharif University of Technology Hesabi, Ashkan (Author) ; Sadrhosseini, Hanieh (Supervisor) ; Shafii, Mohammad Behshad (Supervisor)
    Abstract
    Since oil prices continue to increase, energy conservation remains the prime industrial concern. Existing processes in power plants and oil refineries are not energy efficient as they should be therefore new projects can be defined to increase the energy efficiency without incurring any cost. The most appropriate utility for the processes should be explored to reduce emissions, increase the plant capacities and improve product qualities and energy efficiencies by one coherent strategic plan for the overall site which can be achieved by a full understanding of pinch technology and awareness of the available tools for applying it in practical way. Since the distillation unit of crude oil... 

    Suppression of grain growth in sub-micrometer alumina via two-step sintering method

    , Article Journal of the European Ceramic Society ; Volume 29, Issue 8 , 2009 , Pages 1371-1377 ; 09552219 (ISSN) Razavi Hesabi, Z ; Haghighatzadeh, M ; Mazaheri, M ; Galusek, D ; Sadrnezhaad, Kh ; Sharif University of Technology
    2009
    Abstract
    Two-step sintering (TSS) was applied to suppress the accelerated grain growth of sub-micron (∼150 nm) alumina powder. The application of an optimum TSS regime led to a remarkable decrease of grain size down to ∼500 nm; while the grain size of the full-dense structures produced by conventional sintering ranged between 1 and 2 μm. To find how important the temperatures at sintering steps might be, several TSS regimes were conducted. The results showed that the temperatures at both sintering steps play vital roles in densification and grain growth of the alumina compacts. Based on the results, the optimum regime consisted of heating the green bodies up to 1250 °C (first step) and then holding... 

    Robust Control of Self-Excited Vibration in Machining Arm

    , M.Sc. Thesis Sharif University of Technology Hesabi Hesari, Abbas (Author) ; Moradi, Hamed (Supervisor) ; Movahhedi, Mohammad Reza (Supervisor)
    Abstract
    Nowadays, applications of industrial robots are significantly increasing due to their flexibility, programmable, accuracy, rapidity and etc. Among these, machining robots play an important role at manufacturing industries. One of the main concerns of the researchers, is the tip vibrations of robot arms. In most times, these vibrations are self-excited, unpredictable and intolerable. Thus, finding a method for reducing vibration should be investigated. The purpose of vibration control is vibration suppression to enhance the reliability of the system. The aim of this project is the modeling of the machining robot arm in turning process and then application of robust control to reduce... 

    Design of a Low Power and Robust SRAM Cell Based on FinFET

    , M.Sc. Thesis Sharif University of Technology Sayyah Ensan, Sina (Author) ; Hesabi, Shahin (Supervisor) ; Moaiyeri, Mohammad Hossein (Supervisor)
    Abstract
    By scaling the technology node, leakage power and process variations emerge as the two important factors to design a chip. Static power becomes more important when the number of portable devices which spend most of the time in the idle mode is increasing.Process variations lessen performance, reliability and lead to more leakage power. To mitigate these limitations multiple devices have been proposed to displace Bulk MOSFET.Among these devices we can name FinFET and CNTFET transistors. FinFET transistors due to their superior gate control in compare to Bulk MOSFETs transistor have shown lesser short channel effects, more scalability, more I_on to I_off ratio and lesser process variations.... 

    Design and Analysis of a Simple Low-Power Network-on-Chip

    , M.Sc. Thesis Sharif University of Technology Gheibi Fetrat, Atiyeh (Author) ; Sarbazi Azad, Hamid (Supervisor) ; Hesabi, Shahin (Supervisor)
    Abstract
    The advancement of technology in the semiconductor industry and the resulting increase in the number of transistors on a chip has led to an increase in the number of processing cores an increase in the number of processing cores in a system on chip (SoC). A surge in the number of processing cores, makes their communication more and more noteworthy. This communication is established through the network on chip (NoC). One of the main challenges in NoC design is power management, as it constitutes a high percentage of the overall power consumption of the chip. One of the most power-hungry components of NoC is the router. According to our observation, some of the components of the routers are... 

    , M.Sc. Thesis Sharif University of Technology Sabour Rouh Monfared, Mohammad Amin (Author) ; Haj Sadeghi, Khosro (Supervisor) ; Hesabi, Shahin (Supervisor)
    Abstract
    The fast development of semiconductor industry has moved the design methodology to SoC (System on Chip) design. Due to the increasing number of processing elements, In SoC, buses become the bottleneck of the system and lead to non-efficient designs. NoC (Network onChip) is an efficient solution that eliminates bus bottleneck and it had been introduced as a suitable substructure for interconnecting processing elements. The NoCs were originally built based on Interconnection Networks.They have been proposed as an efficient, scalable, modular and reliable solution to provide on chip communication in any large SoC design. The trend of market to mobile digital systems and battery-powered devices,... 

    The relationship between an EFL teacher's gender and students' willingness to communicate

    , Article International Journal of Communication and Linguistic Studies ; Volume 10, Issue 4 , 2013 , Pages 17-29 ; 23277882 (ISSN) Khosravizadeh, P ; Pakzadian, S. S
    Common Ground Publishing  2013
    Abstract
    Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's... 

    An automated simple algorithm for realistic pore network extraction from micro-tomography images

    , Article Journal of Petroleum Science and Engineering ; Vol. 123, issue , 2014 , pp. 164-171 ; ISSN: 09204105 Rabbani, A ; Jamshidi, S ; Salehi, S
    2014
    Abstract
    Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images... 

    Discrimination of heart arrhythmias using novel features in heart rate phase space

    , Article Computing in Cardiology ; Volume 40 , Sept , 2013 , Pages 1035-1038 ; 23258861 (ISSN); 9781479908844 (ISBN) Moharreri, S ; Rezaei, S ; Salavatian, S
    2013
    Abstract
    In this paper, we try to recognize and distinguish different groups of arrhythmia using novel features which have been obtained from the heart rate's phase space in recent years. For this purpose, we used Triangular Phase Space Mapping (TPSM) and Parabolic Phase Space Mapping (PPSM). For recognition, we used three groups of 15 subjects using the Physionet database (Arrhythmia, Congestive Heart Failure (CHF), and Atrial Fibrillation (AF)) with Normal Sinus Rhythm (NSR). The obtained features discriminate arrhythmia from NSR by p

    An intelligent hybrid classification algorithm integrating fuzzy rule-based extraction and harmony search optimization: Medical diagnosis applications

    , Article Knowledge-Based Systems ; Volume 220 , 2021 ; 09507051 (ISSN) Mousavi, S. M ; Abdullah, S ; Akhavan Niaki, S. T ; Banihashemi, S ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    Uncertainty is a critical factor in medical datasets needed to be overcome for increasing diagnosis efficiency. This paper proposes an intelligent classification algorithm comprising a fuzzy rule-based approach, a harmony search (HS) algorithm, and a heuristic algorithm to classify medical datasets intelligently. Two fuzzy approaches, as well as orthogonal and triangular fuzzy sets, are first utilized to define the attributes of data. Then, an HS algorithm is integrated with a heuristic to generate fuzzy rules to select the best rules in the fuzzy rule-based systems. Moreover, to improve the performance of the proposed classification approach, a three-phase parameter tuning approach is... 

    Performance evaluation of shared hosting security methods

    , Article Proc. of the 11th IEEE Int. Conference on Trust, Security and Privacy in Computing and Communications, TrustCom-2012 - 11th IEEE Int. Conference on Ubiquitous Computing and Communications ; 2012 , Pages 1310-1315 ; 9780769547459 (ISBN) Mirheidari, S. A ; Arshad, S ; Khoshkdahan, S ; Sharif University of Technology
    2012
    Abstract
    Shared hosting is a kind of web hosting in which multiple websites reside on one webserver. It is cost-effective and makes the administration easier for websites' owners. However, shared hosting has some performance and security issues. In default shared hosting configuration, all websites' scripts are executed under the webserver's user account regardless of their owners. Therefore, a website is able to access other websites' resources. This security problem arises from lack of proper isolation between different websites hosted on the same webserver. In this survey, we have examined different methods for handling mentioned security issue. Also we evaluated the performance of mentioned... 

    The behaviour of an artificially cemented sandy gravel

    , Article Geotechnical and Geological Engineering ; Volume 23, Issue 5 , 2005 , Pages 537-560 ; 09603182 (ISSN) Haeri, S. M ; Hosseini, S. M ; Toll, D. G ; Yasrebi, S. S ; Sharif University of Technology
    2005
    Abstract
    The major section of the city of Tehran, Iran has been developed on cemented coarse-grained alluvium. This deposit consists of gravely sand to sandy gravel with some cobbles and is dominantly cemented by carbonaceous materials. In order to understand the mechanical behaviour of this soil, a series of undrained triaxial compression tests and unconfined compression tests were performed on uncemented and artificially cemented samples. Portland cement type I was used as the cementation agent for preparing artificially cemented samples. Uncemented samples and lightly cemented samples (1.5% cement) tested at high confining pressure showed contractive behaviour accompanied with positive excess pore... 

    An imperialist competitive algorithm approach for multi-objective optimization of direct coupling photovoltaic-electrolyzer systems

    , Article International Journal of Hydrogen Energy ; Vol. 39, Issue 33 , 11 November , 2014 , pp. 18743-18757 ; ISSN: 03603199 Maroufmashat, A ; Sayedin, F ; Khavas, S. S
    2014
    Abstract
    In the context of sustainable clean hydrogen production pathways, photovoltaic-electrolyzer systems are one of the most promising alternatives for acquiring hydrogen from renewable energy sources. In fact, determining the optimal set of design and operating variables are always a key issue while coupling directly renewable electricity sources to PEM electrolyzers. Few previous studies have attempted to find the optimal size and operational condition of directly coupled photovoltaic-electrolyzer (PV/El) systems in order to maximize the hydrogen production or to minimize energy transfer loss between photovoltaic devices and the electrolyzer. Nevertheless an easy and efficient approach still... 

    Kalman filter based packet loss replacement in presence of additive noise

    , Article 2012 25th IEEE Canadian Conference on Electrical and Computer Engineering: Vision for a Greener Future, CCECE 2012 ; 2012 ; 9781467314336 (ISBN) Miralavi, S. R ; Ghorshi, S ; Tahaei, A
    2012
    Abstract
    A major problem in real-time packet-based communication systems, is misrouted or delayed packets which results in degraded perceived voice quality. If packets are not available on time, the packets are considered as lost. The easiest solution in a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid degradation in speech quality due to packet loss, a suitable method or algorithm is needed to replace the missing segments of speech. In this paper, we introduce an adaptive filter for replacement of lost speech segment. In this method Kalman filter as a state-space based method will be used to predict the... 

    Investigation of Mesh Sensitivity Influence to Determine Crack Characteristic by Finite Element Methods

    , Article Journal of Failure Analysis and Prevention ; Volume 16, Issue 3 , 2016 , Pages 506-512 ; 15477029 (ISSN) Azimi, M ; Mirjavadi, S. S ; Asli, S. A ; Sharif University of Technology
    Springer New York LLC  2016
    Abstract
    In this research, an extended finite element model has been investigated. Investigation of opening and closure stress always has been one of the difficult parameters to analysis of results; therefore, the utilization of finite element methods would be a good and logical alternative for this purpose. In addition, linear elastic fracture criteria are used for validation of numerical results from the simulation. In this work, a detailed analysis of the influence of different parameters in the results of a specific specimen with a semi-elliptical tooling groove in terms of closure and opening stress is presented, and the impact of optimum element size in fracture characteristic in various load... 

    Investigation of the effect of nanosilica on rheological, thermal, mechanical, structural, and piezoelectric properties of poly(vinylidene fluoride) nanofibers fabricated using an electrospinning technique

    , Article Industrial and Engineering Chemistry Research ; Volume 56, Issue 44 , 2017 , Pages 12596-12607 ; 08885885 (ISSN) Haddadi, S. A ; Ahmad Ramazani, S. A ; Talebi, S ; Fattahpour, S ; Hasany, M ; Sharif University of Technology
    2017
    Abstract
    The effects of different nano-SiO2 contents on the rheological properties of poly(vinylidene fluoride) (PVDF) solution and mechanical, thermal, structural, and piezoelectric properties of composite nanofibers were investigated. Results showed an increase in fiber diameter (∼125 to 350 nm) and ∼450% increase in tensile strength as the content of nano-SiO2 particles increased. The degree of crystallinity decreased by 19% as the nano-SiO2 content increased by 2% (w/w). Further investigation demonstrated that silica could significantly improve the piezoelectric properties of PVDF nanofibers as the output voltage showed an increase in the presence of silica attributed to change in the crystalline... 

    A method for real-time safe navigation in noisy environments

    , Article 2013 18th International Conference on Methods and Models in Automation and Robotics, MMAR 2013, Miedzyzdroje ; 2013 , Pages 329-333 ; 9781467355063 (ISBN) Neyshabouri, S. A. S ; Kamali, E ; Niknezhad, M. R ; Monfared, S. S. M. S ; Sharif University of Technology
    2013
    Abstract
    The challenge of finding an optimized and reliable path dates back to emersion of mobile robots. Several approaches have been developed that have partially answered this need. Satisfying results in previous implementations has led to an increased utilization of sampling-based motion planning algorithms in recent years, especially in high degrees of freedom (DOF), fast evolving environments. Another advantage of these algorithms is their probabilistic completeness that guarantees delivery of a path in sufficient time, if one exists. On the other hand, sampling based motion planners leave no comment on safety of the planned path. This paper suggests biasing the Rapidly-exploring Random Trees... 

    A generalization of the swartz equality

    , Article Glasgow Mathematical Journal ; Vol. 56, issue. 2 , May , 2014 , pp. 381-386 ; ISSN: 00170895 Pournaki, M. R ; Fakhari, S. A. S ; Yassemi, S ; Sharif University of Technology
    2014
    Abstract
    For a given (d-1)-dimensional simplicial complex Γ, we denote its h-vector by h(Γ)=(h 0(Γ),h 1(Γ),...,hd (Γ)) and set h -1(Γ)=0. The known Swartz equality implies that if Δ is a (d-1)-dimensional Buchsbaum simplicial complex over a field, then for every 0 ≤ i ≤ d, the inequality ihi (Δ)+(d-i+1)h i-1(Δ) ≥ 0 holds true. In this paper, by using these inequalities, we give a simple proof for a result of Terai (N. Terai, On h-vectors of Buchsbaum Stanley-Reisner rings, Hokkaido Math. J. 25(1) (1996), 137-148) on the h-vectors of Buchsbaum simplicial complexes. We then generalize the Swartz equality (E. Swartz, Lower bounds for h-vectors of k-CM, independence, and broken circuit complexes, SIAM J.... 

    Hardware-in-the-loop optimization of an active vibration controller in a flexible beam structure using evolutionary algorithms

    , Article Journal of Intelligent Material Systems and Structures ; Vol. 25, issue. 10 , 2014 , p. 1211-1223 Nobahari, H ; Hosseini Kordkheili, S. A ; Afshari, S. S ; Sharif University of Technology
    2014
    Abstract
    In this study, active vibration control of a cantilevered flexible beam structure equipped with bonded piezoelectric sensor/actuators is investigated. The linear quadratic regulator technique together with an observer is adopted to design the controller as well as to provide the full-state feedback. Two different approaches are subsequently used for simultaneously integrated optimization of the controller and observer parameters. In the first approach, a linear experimental model of the system is obtained using identification techniques, and the optimization is then performed based on a computer simulation of the system. However, in the second approach, a hardware-in-the-loop optimization...