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    The superconvergence patch recovery technique and data transfer operators in 3D plasticity problems

    , Article Finite Elements in Analysis and Design ; Volume 43, Issue 8 , 2007 , Pages 630-648 ; 0168874X (ISSN) Khoei, A. R ; Gharehbaghi, S. A ; Sharif University of Technology
    A decade has passed since the first appearance of the superconvergent patch recovery (SPR) method introduced by Zienkiewicz and Zhu [The superconvergence patch recovery and a posteriori error estimates, part I: the recovery techniques, Int. J. Numer. Methods Eng. 33 (1992) 1331-1364; The superconvergence patch recovery and a posteriori error estimates, part II: error estimates and adaptivity, Int. J. Numer. Methods Eng. 33 (1992) 1365-1380; Superconvergence and the superconvergent patch recovery, Finite Elem. Anal. Des. 19 (1995) 11-23]. The method is now widely used in engineering practices for its robustness and efficiency in computer implementation. This paper presents an extension of the... 

    Bandwidth adapted hierarchical multicast overlay

    , Article Proceedings - 5th International Multi-Conference on Computing in the Global Information Technology, ICCGI 2010, 20 September 2010 through 25 September 2010 ; 2010 , Pages 262-267 ; 9780769541815 (ISBN) Bagheri, M ; Movaghar, A ; Khodaparast, A. A ; Sharif University of Technology
    As the infrastructure-centric model of peer-to-peer streaming, recent overlay construction schemes compose a hierarchical topology of peers by grouping them into clusters. There is a server in each cluster that receives data from the source and relays it to its cluster members. In this paper, we propose an alternative infrastructure-centric peer-to-peer framework called BAHMO that constructs a hierarchical multicast tree. BAHMO does not utilize server bandwidth and rely only on peer bandwidth for data transfers. It achieves both the stability of the infrastructure-centric model and the bandwidth efficiency of the fully-distributed model. Bandwidth assignment for inter-cluster data transfers... 

    PAM: A packet manipulation mechanism for mitigating crosstalk faults in NoCs

    , Article Proceedings - 15th IEEE International Conference on Computer and Information Technology, CIT 2015, 14th IEEE International Conference on Ubiquitous Computing and Communications, IUCC 2015, 13th IEEE International Conference on Dependable, Autonomic and Secure Computing, DASC 2015 and 13th IEEE International Conference on Pervasive Intelligence and Computing, PICom 2015, 26 October 2015 through 28 October 2015 ; October , 2015 , Pages 1895-1902 ; 9781509001545 (ISBN) Shirmohammadi, Z ; Ansari, M ; Abharian, S. K ; Safari, S ; Miremadi, S. G ; Atzori L ; Jin X ; Jarvis S ; Liu L ; Calvo R. A ; Hu J ; Min G ; Georgalas N ; Wu Y ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    This paper proposes an efficient mechanism that mitigates crosstalk faults in Network-on-Chips (NoCs). This is done by using a Packet Manipulating mechanism called PAM for reliable data transfer of NoCs. PAM investigates the transitions of a packet to minimize the forbidden transition patterns appearing during the flit traversal in NoCs. To do this, the content of a packet is manipulated using three different manipulating mechanisms. In other words, PAM manipulates the content of packet in three manipulating modes including: vertical, horizontal and diagonal modes. Then, comparing the transitions of these manipulating mechanisms, a packet with minimum numbers of transitions is selected to be... 

    Efficient codebook design for digital communication through compressed voice channels

    , Article IET Communications ; Volume 10, Issue 18 , 2016 , Pages 2613-2620 ; 17518628 (ISSN) Boloursaz Mashhadi, M ; Behnia, F ; Sharif University of Technology
    Institution of Engineering and Technology  2016
    The common voice channels existing in cellular communication networks provide reliable, ubiquitously available and top priority communication mediums. These properties make voice dedicated channels an ideal choice for high priority, real time communication. However, such channels include voice codecs that hamper the data flow by compressing the waveforms prior to transmission. This study designs codebooks of speech-like symbols for reliable data transfer through the voice channel of cellular networks. An efficient algorithm is proposed to select proper codebook symbols from a database of natural speech to optimise a desired objective. Two variants of this codebook optimisation algorithm are... 

    On designing an efficient numerical-based forbidden pattern free crosstalk avoidance codec for reliable data transfer of NoCs

    , Article Microelectronics Reliability ; Volume 63 , 2016 , Pages 304-313 ; 00262714 (ISSN) Shirmohammadi, Z ; Miremadi, S. G ; Sharif University of Technology
    Elsevier Ltd 
    Inter-wire coupling capacitances can lead to crosstalk fault that is strongly dependent on the transition patterns appearing on the wires. These transition patterns can cause mutual influences between adjacent wires of NoCs and as a result threaten the reliability of data transfer seriously. To increase the reliability of NoCs against the crosstalk fault, Forbidden Pattern Free (FPFs) codes are used. To generate FPF codes, numerical systems are among the overhead-efficient mechanisms. The algorithms of numerical systems have direct effect on the amounts of the codec overheads including power consumption, area occupation and performance of NoCs. To find an overhead-efficient numerical system,... 

    Wireless interfacing to cortical neural recording implants using 4-FSK modulation scheme

    , Article IEEE International Conference on Electronics, Circuits, and Systems, 6 December 2015 through 9 December 2015 ; Volume 2016 March , 2016 , Pages 221-224 ; 9781509002467 (ISBN) Eslampanah Sendi, M. S ; Judy, M ; Molaei, H ; Sodagar, A. M ; Sharifkhani, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    This paper used a 4-level frequency shift keying (4-FSK) modulation scheme to enhance the density of wireless data transfer from implantable biomedical microsystems to the outside world. Modeling and simulation of the wireless channel for 4-FSK modulation in the case of a neural recording implant has been done. To realize the 4-FSK scheme, the modulator and demodulator circuits are proposed, designed and simulated in a 0.18-μm CMOS process, and in the 174-216 MHz frequency band at a data rate of 13.5 Mbps. Operated using a 1.8 V supply voltage, the modulator circuit consumes a power of 7.8 μW  

    Three-dimensional data transfer operators in plasticity using SPR technique with C0, C1 and C2 continuity

    , Article Scientia Iranica ; Volume 15, Issue 5 , 2008 , Pages 554-567 ; 10263098 (ISSN) Khoei, A. R ; Gharehbaghi, S. A ; Sharif University of Technology
    Sharif University of Technology  2008
    In this paper, the data transfer operators are developed in three-dimensional elasto-plasticity using the Superconvergent Patch Recovery (SPR) method. The transfer operators are defined for mapping of the state and internal variables between different meshes. The internal variables are transferred from Gauss points of old mesh to the nodal points. The variables are then transferred from the nodal points of old mesh to the nodal points of new mesh. Finally, the values are computed at the Gauss points of new mesh using their values at the nodal points. Aspects of the transfer operators are presented in a three-dimensional superconvergent path recovery technique, based on C0, C1 and C2... 

    Three-dimensional superconvergent patch recovery method and its application to data transferring in small-strain plasticity

    , Article Computational Mechanics ; Volume 41, Issue 2 , 2008 , Pages 293-312 ; 01787675 (ISSN) Gharehbaghi, S. A ; Khoei, A. R ; Sharif University of Technology
    Springer Verlag  2008
    In this paper, a 3D Superconvergent Patch Recovery (SPR) method is developed for data transferring in elasto-plasticity. The transfer operators are presented for mapping of the state and internal variables between different meshes. In order to transfer the history-dependent variables from old mesh to new one, the internal variables are firstly mapped from the Gauss points to nodal points of old mesh, the variables are then transferred from nodal points of old mesh to nodal points of new mesh, and the values are finally transferred from the nodal points to Gauss points of new mesh. As the solution procedure cannot be re-computed from the initial state, it is continued from the previously... 

    Improving mobile banking security using steganography

    , Article 4th International Conference on Information Technology-New Generations, ITNG 2007, Las Vegas, NV, 2 April 2007 through 4 April 2007 ; 2007 , Pages 885-887 ; 0769527760 (ISBN); 9780769527765 (ISBN) Shirali Shahreza, M ; Sharif University of Technology
    Upon development of m-commerce as one of the new branches of e-commerce, m-banking has emerged as one of the main divisions of m-commerce. As the m-banking was received very well, it has embarked upon supply of various services based on different systems and with the aid of various services such as the Short Messaging Service (SMS). However, in spite of its advantages, m-banking is facing some challenges as well. One of these challenges is the issue of security of this system. This paper presents a method for increasing security of the information requested by users with the use of steganography method. In this method, instead of direct sending of the information, it is hidden in a picture... 

    Secure data transmission using qubits

    , Article 6th IEEE International Conference on Computer and Information Technology, CIT 2006, Seoul, 20 September 2006 through 22 September 2006 ; 2006 ; 076952687X (ISBN); 9780769526874 (ISBN) Marvian, I ; Hosseini Khayat, S ; Sharif University of Technology
    A quantum protocol for secure transmission of data using qubits is presented. This protocol sends one qubit in a round-trip to transmit one bit of data. The protocol offers an improvement over the BB84 QKD protocol. BB84, in conjunction with one-time pad encryption, has been shown to be unconditionally secure. However its security relies on the assumption that the qubit source device does not emit multiple replicas of the same qubit for each transmitted bit. If this happens a multi-qubit emission attack can be launched. In addition, BB84 cannot be used to send predetermined bit strings as it generates a random bit string in the process. Our protocol does not have the above drawbacks, but... 

    Efficient Cooperative Power and Data Transmission in Wireless Communication Networks

    , M.Sc. Thesis Sharif University of Technology Haghifam, Mahdi (Author) ; Nasiri Kenari, Masoumeh (Supervisor) ; Ashtiani, Farid (Supervisor)
    Relay-assisted communication is one of the promising techniques that have been proposed for wireless networks. The main idea of a relay network is to improve data transmission efficiency by using intermediate relay nodes which support data transmission from a source to a destination. From another perspective, energy consumption has recently become an important consideration for design of wireless communication networks. The shrinking size and increasing density of next-generation wireless devices imply reduced battery capacities, indicating that designing energy efficient networks is of paramount importance. In this regard, recent emphasis on green communications has generated great... 

    Modem based on sphere packing techniques in high-dimensional Euclidian sub-space for efficient data over voice communication through mobile voice channels

    , Article IET Communications ; Volume 9, Issue 4 , 2015 , Pages 508-516 ; 17518628 (ISSN) Kazemi, R ; Boloursaz Mashhadi, M ; Heidari Khoozani, M ; Behnia, F ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    The increased penetration of cellular networks has made voice channels widely available ubiquitously. On the other hand, mobile voice channels possess properties that make them an ideal choice for high priority, low-rate real-time communications. Mobile voice channel with the mentioned properties, could be utilised in emergency applications in vehicular communications area such as the standardised emergency call system planned to be launched in 2015. This study aims to investigate the challenges of data transmission through these channels and proposes an efficient data transfer structure. To this end, a proper statistical model for the channel distortion is proposed and an optimum detector... 

    A high data-rate energy-efficient interference-tolerant fully integrated CMOS frequency channelized UWB transceiver for impulse radio

    , Article IEEE Journal of Solid-State Circuits ; Volume 43, Issue 4 , 2008 , Pages 974-980 ; 00189200 (ISSN) Medi, A ; Namgoong, W ; Sharif University of Technology
    A pulse-based ultra-wideband transceiver (UWB-IR) operating in the 3.25-4.75 GHz band designed for low power and high data rate communication is implemented in 0.18 μm CMOS technology. When operating at 1 Gbps data rate, it dissipates 98 mW (98 pJ/b) in the receive-mode and 108 mW (108 pJ/b) in the transmit-mode from a 1.8 V supply [1]. Compared to UWB transceivers reported in the literature, this chip dissipates the lowest energy per bit. In addition, the combination of the frequency channelized architecture, high-linearity RF circuits, aggressive baseband filtering, and low local oscillator spurs results in an interference-tolerant receiver that is able to co-exist with systems operating... 

    Effect of leaky-bucket-based traffic shaping on capacity enhancement for VSG-CDMA cellular networks

    , Article 2007 IEEE Wireless Communications and Networking Conference, WCNC 2007, Kowloon, 11 March 2007 through 15 March 2007 ; June , 2007 , Pages 3695-3699 ; 15253511 (ISSN); 1424406595 (ISBN); 9781424406593 (ISBN) Seyfi, A ; Ashtiani, F ; Sharif University of Technology
    In this paper, we propose data traffic shaping via leaky bucket in order to reduce outage probability and enhance capacity of voice users for uplink variable spreading gain codedivision multiple-access (VSG-CDMA) cellular networks. In order to analyze the effect of leaky bucket mechanism, we employ a closed Jackson queueing network with arbitrary service time distributions to model different states of a typical traffic-shaped data user. By solving the concerned queueing network, we obtain the steady state probability with which a typical data user exist at each state. By aggregating the effects of all data and voice users we obtain mean and variance of interference and compute the outage... 

    Error estimation, adaptivity and data transfer in enriched plasticity continua to analysis of shear band localization

    , Article Applied Mathematical Modelling ; Volume 31, Issue 6 , 2007 , Pages 983-1000 ; 0307904X (ISSN) Khoei, A. R ; Asil Gharebaghi, S ; Tabarraie, A. R ; Riahi, A ; Sharif University of Technology
    In this paper, an adaptive FE analysis is presented based on error estimation, adaptive mesh refinement and data transfer for enriched plasticity continua in the modelling of strain localization. As the classical continuum models suffer from pathological mesh-dependence in the strain softening models, the governing equations are regularized by adding rotational degrees-of-freedom to the conventional degrees-of-freedom. Adaptive strategy using element elongation is applied to compute the distribution of required element size using the estimated error distribution. Once a new mesh is generated, state variables and history-dependent variables are mapped from the old finite element mesh to the... 

    Efficient fully format compliant selective scrambling methods for compressed video streams

    , Article Advanced International Conference on Telecommunications andInternational Conference on Internet and Web Applications and Services, AICT/ICIW'06, Guadelope, 19 February 2006 through 25 February 2006 ; Volume 2006 , 2006 , Pages 42- ; 0769525229 (ISBN); 9780769525228 (ISBN) Kiaei, M. S ; Ghaemmaghami, S ; Khazaei, S ; Sharif University of Technology
    Format compliance, a desirable feature of multimedia security systems, means that the secured bitstream resembles the unprotected compressed bitstream. It is called full format compliance, if the scrambled stream can be decoded by a typical decoder. In this paper, we address the issues that are to be carefully taken into account to develop efficient fully format compliant scrambling methods for compressed video. We also propose new selective scrambling methods for securing compressed video streams. The security issues, in different parts of these scrambling methods, are analyzed and their impact on bit-rate and complexity is discussed. We show that our scrambling methods provide... 

    A near optimum RREQ flooding algorithm in sensor networks

    , Article 2006 IEEE Wireless Communications and Networking Conference, WCNC 2006, Las Vegas, NV, 3 April 2006 through 6 April 2006 ; Volume 1 , 2006 , Pages 425-430 ; 15253511 (ISSN); 1424402700 (ISBN); 9781424402700 (ISBN) Ghiassi Farrokhfal, Y ; Arbab, V. R ; Pakravan, M. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    Most of the energy efficient routing algorithms proposed for sensor networks are reactive routing algorithms. By definition, reactive algorithms are those in which routes are constructed whenever there is data transmission. In such algorithms, to transmit data packets from a certain transmitter to the corresponding receiver, efficient route will be constructed using RREQ delivery. This delivery is performed via flooding and modified flooding algorithms. One of the most important criteria of such flooding algorithm is not to miss the best final route during RREQ delivery. Most of major algorithms ignored this fact and instead tried to minimize energy consumption during flooding algorithm. But... 

    An optimisation model for cloud-based supply chain network design: Case study in the banking industry

    , Article International Journal of Communication Networks and Distributed Systems ; Volume 27, Issue 2 , 2021 , Pages 119-146 ; 17543916 (ISSN) Hajipour, V ; Akhavan Niaki, S. T ; Rahbarjou, M ; Sharif University of Technology
    Inderscience Publishers  2021
    New technologies provide tremendous integration opportunities not only for the flow of goods and services but also for managing information and financial data. Flexibility and agility are important metrics in organisations. Cloud technology can have a significant impact on improving flexibility and agility in organisations through faster data transfer between supply chain components. In this study, we present an optimisation model for cloud-based supply chain network design (SCND) problem by optimising the costs and quality of service (QoS). We present a case study in the banking industry to show the applicability and exhibit the efficacy of the proposed optimisation model. Copyright © 2021... 

    CICADA: A novel scheme for improving TCP performance over wireless links

    , Article Wireless Communications and Mobile Computing ; Volume 5, Issue 4 , 2005 , Pages 439-458 ; 15308669 (ISSN) Ghaboosi, K ; Hossein Khalaj, B ; Sharif University of Technology
    In this paper, by making slight modifications in protocol stack of wireless access points, the proposed CICADA scheme aims at isolating problems related to wireless section of a transmission control protocol (TCP) connection from its wired portion, using IP spoofing and virtual protocol stack scheme. As the simulation results for an 802.11 based system show, the proposed scheme improves the overall network throughput for both DCF and PCF scenarios, while reducing the mean and variance of end-to-end delay for voice and video flows due to smarter bandwidth allocation to elastic and real-time traffic. In addition, the proposed scheme uses a centralized network address translation (NAT)... 

    RAQ: A range-queriable distributed data structure

    , Article 31st Conference on Current Trends in Theory and Practice of Computer Science, Liptovsky Jan, 22 January 2005 through 28 January 2005 ; Volume 3381 , 2005 , Pages 269-277 ; 03029743 (ISSN) Nazerzadeh, H ; Ghodsi, M ; Sharif University of Technology
    Springer Verlag  2005
    Different structures are used in peer-to-peer networks to represent their inherently distributed, self-organized, and decentralized memory structure. In this paper, a simple range-queriable distributed data structure, called RAQ, is proposed to efficiently support exact match and range queries over multi-dimensional data. In RAQ, the key space is partitioned among the network with n nodes, in which each element has links to O(log n) other elements. We will show that the look-up query for a specified key can be done via O(log n) message passing. Also, RAQ handles range-queries in at most O(logn) communication steps. © Springer-Verlag Berlin Heidelberg 2005