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    Designing optimal tuned mass dampers for nonlinear frames by distributed genetic algorithms

    , Article Structural Design of Tall and Special Buildings ; Volume 21, Issue 1 , 2012 , Pages 57-76 ; 15417794 (ISSN) Mohebbi, M ; Joghataie, A ; Sharif University of Technology
    2012
    Abstract
    In this paper, the capabilities of tuned mass dampers (TMDs) for the mitigation of response of nonlinear frame structures subjected to earthquakes have been studied. To determine the optimal parameters of a TMD, including its mass, stiffness and damping, we developed an optimization algorithm based on the minimization of a performance index, defined as a function of the response of the nonlinear structure to be controlled. Distributed genetic algorithm has been used to solve the optimization problem. For illustration, the method has been applied to the design of a linear TMD for an eight-story nonlinear shear building with bilinear hysteretic material behavior subjected to earthquake. The... 

    Optimal TMDs for improving the seismic performance of historical buildings

    , Article Scientia Iranica ; Volume 23, Issue 1 , 2016 , Pages 79-90 ; 10263098 (ISSN) Mohebbi, M ; Joghataie, A ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    In this paper, optimal design and assessment of the capability of Tuned Mass Dampers (TMDs) in improving the seismic behavior of Confined masonry walls, as the main element of historical buildings, has been studied. For this purpose, the design parameters of TMDs have been determined through minimization of wall response using Genetic Algorithms (GAs). To simulate the behavior of Confined masonry wall under earthquake, the triple linear shear beam model has been used. For illustration, the method has been tested on Confined masonry walls equipped with linear TMDs. To study the effects of frequency content and Peak Ground Acceleration (PGA) of earthquake records on the performance of TMDs,... 

    Design and Hardware Implementation of Optical Character Recognition

    , M.Sc. Thesis Sharif University of Technology Dezfuli, Sina (Author) ; Hashemi, Matin (Supervisor)
    Abstract
    The objective of OCR systems is to retrieve machine-encoded text from a raster image. Despite the abundance of powerful OCR algorithms for English, there are not many for Farsi. Our proposed algorithm is comprised of pre-processing, line detection, sub-word detection and segmentation, feature extraction and classification. Furthermore, hardware implementation and acceleration of this system on a GPGPU is presented. This algorithm was tested on 5 fonts including Titr, Lotus,Yekan, Koodak and Nazanin and an average accuracy above 90% was achieved  

    Efficient Implementation of Compressed Deep Convolutional Neural Networks

    , M.Sc. Thesis Sharif University of Technology Afshar, Mohammad (Author) ; Hashemi, Matin (Supervisor)
    Abstract
    Many mobile applications running on smartphones, wearable devices, tiny autonomous robots and IoT devices would potentially benefit from the accuracy and scalability of deep CNN-based machine learning algorithms. However,performance and energy consumption limitations make the execution of such computationally intensive algorithms on embedded mobile devices prohibitive.We present a GPU-accelerated engine, dubbed mCNN, for execution of trained deep CNNs on mobile platforms. The proposed solution takes the trained model as input and automatically optimizes its parallel implementation on the target mobile platform for efficient use of hardware resources such as mobile GPU threads and SIMD units.... 

    Design and Efficient Hardware Implementation of Spiking Neural Networks on FPGA

    , M.Sc. Thesis Sharif University of Technology Amirshahi, Alireza (Author) ; Hashemi, Matin (Supervisor)
    Abstract
    Spiking Neural Networks(SNN) are networks which are consisted of layers of neurons, like other typical artificial neural networks. The main difference between SNN and other neural networks is the type of data transportation among neurons which is done by spikes. Spiking neural networks and their models are considered as the nearest networks and neurons to animals’ nervous systems. In aspects of hardware implementation, the type of data transportation in SNN causes them to be ultra-low power. So, implementation of these networks on chips like FPGA and also usage of SNN in applications with high processing load have startling germination, recently. In this work, we have tried to propose some... 

    Parallel Implementation of Telecommunication Decodings in Real-time

    , M.Sc. Thesis Sharif University of Technology Jafarzadeh, Ali (Author) ; Hashemi, Matin (Supervisor)
    Abstract
    Many chip manufacturers have recently introduced high-performance deep-learning hardware accelerators. In modern GPUs, programmable tensor cores accelerate the heavy operations involved in deep neural networks. This paper presents a novel solution to re-purpose tensor cores in modern GPUs for high-throughput implementation of turbo decoders. Turbo codes closely approach Shannon’s limit on channel capacity, and are widely used in many state-of-the-art wireless systems including satellite communications and mobile communications. Experimental evaluations show that the proposed solution achieves about 1.2 Gbps throughput, which is higher compared to previous GPU-accelerated solutions  

    Disentangled Representation Learning for Automated Clothe Image Synthesis on the Body

    , M.Sc. Thesis Sharif University of Technology Johary, Iman (Author) ; Hashemi, Matin (Supervisor)
    Abstract
    There have been many works on generative networks and image generation in the past few years, but the problem with this work is that there is no control over the generated images. The goal of disentangled image synthesis is to generate new images with specific detail and have control over the generated images. Image-based virtual try-on aims to synthesize the customer image with an in-shop clothes image to acquire seamless and natural try-on results, which have attracted increasing attention. The main procedures of image-based virtual try-on usually consist of clothes image generation and try-on image synthesis. In contrast, prior arts cannot guarantee satisfying clothes results when facing... 

    Prediction of formability of tailor welded blanks by modification of MK model

    , Article International Journal of Mechanical Sciences ; Volume 61, Issue 1 , 2012 , Pages 44-51 ; 00207403 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    2012
    Abstract
    A new model is proposed to predict the Forming Limit Diagrams (FLDs) of Tailor Welded Blanks (TWBs). This model is derived by modification of the Marciniak and Kuczynski (MK) analysis and imposing the weld constraints to deformation state of each blank at each strain increment. Based on this model, it is possible to predict the strains of both weaker and stronger blanks once necking occurs. By comparison to the experimental results of two laser welded TWBs, it is demonstrated that this model provides a close prediction of FLD of TWBs, when necking occurs far from the weld line at a region out of HAZ (Heat Affected Zone) and close to it so that it is affected by the weld line constraints  

    Fabrication of copper/aluminum composite tubes by spin-bonding process: Experiments and modeling

    , Article International Journal of Advanced Manufacturing Technology ; Volume 54, Issue 9-12 , November , 2011 , Pages 1043-1055 ; 02683768 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    2011
    Abstract
    The aim of this work is to produce two layered thin-walled Cu/Al composite tube by the spin-bonding process. The process is utilized to bond the aluminum tube into the copper one at thickness reductions of 20-60% and process temperatures of 25°C, 130°C, and 230°C. The bond strength is measured by T-peeling test, and the bond interfaces are examined by metallography and scanning electron microscopy (SEM). The results show that after a threshold thickness reduction of about 30%, the bond strength increased with the amount of deformation. SEM fractography of the peel surfaces confirms that the copper oxide film is broken in a shear manner during deformation. Severe shear strains applied during... 

    Accumulative spin-bonding (ASB) as a novel SPD process for fabrication of nanostructured tubes

    , Article Materials Science and Engineering A ; Volume 528, Issue 1 , November , 2010 , Pages 180-188 ; 09215093 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    2010
    Abstract
    A novel SPD process for manufacturing of high strength tubes and cylinders by accumulative spin-bonding (ASB) is proposed. It is demonstrated that due to incremental deformation in this process, high strain rate without considerable temperature rise is achieved. This is accompanied with a high value of Zener-Hollomon parameter as a characteristic of this SPD process. ASB was applied to a commercially pure aluminum up to four cycles and its effects on the microstructure and mechanical properties were examined by optical microscopy, TEM, EBSD, microhardness and tension tests. The results show that ultra-fine grains are developed during the process by formation of subgrains at early stages... 

    A novel spin-bonding process for manufacturing multilayered clad tubes

    , Article Journal of Materials Processing Technology ; Volume 210, Issue 3 , 2010 , Pages 510-517 ; 09240136 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    2010
    Abstract
    Utilizing the so-called tube spinning, a cold-bonding process entitled as "spin-bonding" is developed to produce seamless thin-walled clad tubes and cylinders. By this method, two layers of AA 1050 tubes were successfully bonded together to form a clad tube at room temperature. Based on mechanical aspects of the tube spinning process, the mechanism of spin-bonding is explained in two stages: surface preparation before occurrence of a stable bond and bond strengthening thereafter. The effects of process temperature, thickness reduction, feed rate and roller attack angle as the parameters of tube spinning on the bond strength are studied. It is shown that the bond strength increases by... 

    Pain level estimation in video sequences of face using incorporation of statistical features of frames

    , Article 9th Iranian Conference on Machine Vision and Image Processing, 18 November 2015 through 19 November 2015 ; Volume 2016-February , 2015 , Pages 172-175 ; 21666776 (ISSN) ; 9781467385398 (ISBN) Mohebbi Kalkhoran, H ; Fatemizadeh, E ; Sharif University of Technology
    IEEE Computer Society  2015
    Abstract
    Pain level estimation from videos of face has many benefits for clinical applications. Most of the previous works focused only on pain detection task. However, pain level estimation of video sequences has been discussed fewer. In this work, we have proposed a new regression-based approach to estimate the pain level of video sequences. As the first step, facial expression-related features were extracted from each frame, this task was done by reducing identity-related features using the robust principal component analysis decomposition. Then, we used the minimum, maximum, and mean of the features of frames in a sequence to represent that sequence by a fixed-length feature vector. After this,... 

    Constitutive equation and FEM analysis of incremental cryo-rolling of UFG AA 1050 and AA 5052

    , Article Journal of Materials Processing Technology ; Volume 255 , 2018 , Pages 35-46 ; 09240136 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    In this study, ultrafine grained aluminum sheets AA1050 and AA5052 are incrementally cryo-rolled after precooling in liquid nitrogen. Cryogenic deformation is considered as an effective approach to postpone saturation of the grain refinement by conventional severe plastic deformation. However, for a quantitative understanding of the resulted microstructure and mechanical properties, accurate values of the deformation parameters (strain, strain rate and temperature) are needed. The aim of this study is, therefore, to find values of the applied cryo-rolling parameters. As the experimental measurements of parameters such as temperature are infeasible in the thin specimens, a FEM simulation is... 

    Development of equations for strain rate sensitivity of UFG aluminum as a function of strain rate

    , Article International Journal of Plasticity ; Volume 90 , 2017 , Pages 167-176 ; 07496419 (ISSN) Mohebbi, M. S ; Akbarzadeh, A ; Sharif University of Technology
    2017
    Abstract
    Strain rate sensitivity (m-value) of ultrafine grain (UFG) AA 1050 and AA 5052 sheets processed by accumulative roll-bonding is investigated versus strain rate by stress relaxation (SR) test at ambient temperature. The results show a weak viscous nature of deformation for AA 5052 specimens as compared to AA 1050 ones. So that much less stress relaxation and negligible strain rate sensitivity are obtained for this material due to dislocation and grain boundary mobility limitation caused by Mg solute atoms. In order to formulate strain rate sensitivity of UFG aluminum as a function of strain rate, three phenomenological and two empirical models are developed and assessed by the experimental... 

    Viterbi Decoder Implementation on GPGPU

    , M.Sc. Thesis Sharif University of Technology Mohammadidoost, Alireza (Author) ; Hashemi, Matin (Supervisor)
    Abstract
    In this project, a method is emoloyed to implement a Viterbi decoder on GPGPU. This method is based on combining all steps of the algorithm. This combination has some challenges that are related to differences between different steps of the algorithm. So in this project, some solutions are found to handle these challenges and a high-throughput Viterbi decoder is acheived  

    Manufacturing of Composite and Nanostructured Thin Walled Tubes by ASB Process

    , M.Sc. Thesis Sharif University of Technology Mohebbi, Mohammad Sadegh (Author) ; Akbarzadeh, Abbas (Supervisor)
    Abstract
    In this study, utilizing the so-called “flow forming”, a cold-bonding process is developed to produce multi-layered thin-walled tubes and cylinders. In this process, which is entitled as “spin-bonding”, two layers of tubes are bonded by thickness reduction. Al/Al and Cu/Al tubes were bonded at various temperatures, thickness reductions, feed rates and roller attack angles. The bonding quality was examined by peel test, metallography and SEM fractography. Moreover, spin-bonding was accumulatively applied to aluminum tubes up to 4 cycles as a severe plastic deformation (SPD) for thin-walled tubes and cylinders entitled as “Accumulative Spin-Bonding” (ASB). Beside of experimental works,... 

    Peak Temperature Recduction in 3D NoCs using Task Migration

    , M.Sc. Thesis Sharif University of Technology Mohebbi Moghaddam, Monireh (Author) ; Hessabi, Shaahin (Supervisor)
    Abstract
    Combination of 3D stacking and network-on-chip (NoC), known as 3D NoC, has some advantages such as reduced propagation delay, chip area and interconnect, and power consumption, and bandwidth increase. Despite these advantages, the increased power density per chip area due to area decrease causes thermal problems in 3D NoCs to be more critical than 2D NoCs. Therefore, design of temperature management algorithms is essential for these systems. One of the dynamic thermal management techniques is task migration that balances generated thermal among cores.In this thesis, we propose a task migration scheme using feedback control for 3D NoCs. The main purpose of this scheme is to decrease the peak... 

    Effect of Cryogenic SPD with Various Strain Conditions on Development of Nano and Bimodal Structures in Al Alloys

    , Ph.D. Dissertation Sharif University of Technology Mohebbi, Mohammad Sadegh (Author) ; Akbarzadeh, Abbas (Supervisor)
    Abstract
    Amount of strain has been always considered as the primary parameter affecting the microstructural and strength evolutions during Severe Plastic Deformation (SPD). However, these evolutions unavoidably saturate in large strains under deformation with constant conditions, i.e. constant deformation temperature, strain rate and strain path. In this study, effects of these factors on the microstructural and flow behavior of Ultra-Fine Grain (UFG) aluminum (AA 1050 and AA 5052) processed by Accumulative Roll-Bonding (ARB) are investigated. The flow behavior and its time-dependent aspect are evaluated up to large strains by Plane Strain Compression (PSC) and Stress Relaxation (SR) tests. ... 

    Higher prevalence of asymptomatic or mild COVID-19 in children, claims and clues

    , Article Journal of Medical Virology ; Volume 92, Issue 11 , May , 2020 , Pages 2257-2259 Miri, S. M ; Noorbakhsh, F ; Mohebbi, S. R ; Ghaemi, A
    John Wiley and Sons Inc  2020

    Hysteretic response of confined masonry walls by Prandtl neural networks

    , Article 1st International Conference on Advances and Trends in Engineering Materials and their Applications, AES-ATEMA'2007, Montreal, QC, 6 August 2007 through 10 August 2007 ; 2007 , Pages 525-533 ; 19243642 (ISSN) ; 0978047907 (ISBN); 9780978047900 (ISBN) Joghataie, A ; Farrokh, M ; Mohebbi, M ; Sharif University of Technology
    2007
    Abstract
    In this paper a new method of modeling shear force-displacement relationship for confined masonry walls by neural networks has been presented. Although the mathematical models have been very useful in the simulations so far, however developing more accurate models is necessary. While developing precise mathematical models for highly hysteretic materials is itself challenging and practically cumbersome, the use of learning algorithms is an attractive alternative. The issue of material modeling by neural networks has been a challenging one itself, noticing available neural networks have some limitations in the learning of non-linearity. In this paper a new type neural network, called Prandtl...