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    Work-in-Progress: heterogeneous redundancy to address performance and cost in multi-core SIMT

    , Article Proceedings of the 12th IEEE/ACM/IFIP International Conference on Hardware/Software Codesign and System Synthesis Companion, CODES 2017, 15 October 2017 through 20 October 2017 ; 2017 ; 9781450351850 (ISBN) Naghashi, M ; Mozafari, S. H ; Hessabi, S ; Sharif University of Technology
    As manufacturing processes scale to smaller feature sizes and processors become more complex, it is becoming challenging to have fabricated devices that operate according to their speciication in the irst place: yield losses are mounting [3]. In this work, we investigate adding heterogeneous hot redundancy (i.e., the architecture of redundant hot cores is diferent from the baseline cores) to improve the cost and performance of multicore single-instruction, multiple-thread (SIMT) architectures. We propose to utilize x86 out of order (OoO) cores as redundancy in SIMT processors. In this case, dice with unused functional redundancies can beneit from two types of processing cores (OoO and SM)  

    Fuzzy reliability optimization models for redundant systems [electronic resource]

    , Article International Journal of Industrial engineering ; July 2008, Vol. 4, No. 7, 1-9 Nematian, J. (Javad) ; Eshghi, Kourosh ; Eshraghniaye Jahromi, Abdolhamid ; Sharif University of Technology
    In this paper, a special class of redundancy optimization problem with fuzzy random variables is presented. In this model, fuzzy random lifetimes are considered as basic parameters and the Er-expected of system lifetime is used as a major type of system performance. Then a redundancy optimization problem is formulated as a binary integer programming model. Furthermore, illustrative numerical examples are also given to clarify the methods discussed in this paper  

    Availability optimization of a series system with multiple repairable load sharing subsystems considering redundancy and repair facility allocation

    , Article International Journal of Systems Assurance Engineering and Management ; Volume 4, Issue 3 , September , 2013 , Pages 262-274 ; 09756809 (ISSN) Yahyatabar Arabi, A .A ; Eshraghniaye Jahromi, A ; Sharif University of Technology
    Redundancy technique is considered as a way to enhance the reliability and availability of a system. This paper models availability of a repairable system with multiple subsystems in which the involved components follow the load sharing strategy. In redundancy allocation problems, the redundancy level is just considered, whereas, in this paper, the number of repair facility (repairman) is added to the decision variables. The goal is to find the optimal number of repairmen and redundant components in each subsystem for optimization of availability subject to weight, cost and volume constraints. The main contribution of this study is to present a straightforward model for availability... 

    A robust multi-objective production planning

    , Article International Journal of Industrial Engineering Computations ; Volume 1, Issue 1 , 2010 , Pages 73-78 ; 19232926 (ISSN) Gharakhani, M ; Taghipour, T ; Jalali Farahani, K ; Sharif University of Technology
    When a production facility is designed, there are various parameters affecting the number machines such as production capacity and reliability. It is often a tedious task to optimize different objectives, simultaneously. The other issue is the uncertainty in many design parameters which makes it difficult to reach a desirable solution. In this paper, we present a new mathematical model with two objectives. The primary objective function is considered to be the production capacity and the secondary objective function is total reliability. The proposed model is formulated on different units of production which are connected together in serial form and for each unit, we may have various... 

    A new model for reliability optimization of series-parallel systems with non-homogeneous components

    , Article Reliability Engineering and System Safety ; Volume 157 , 2017 , Pages 101-112 ; 09518320 (ISSN) Feizabadi, M ; Eshraghniaye Jahromi, A ; Sharif University of Technology
    Elsevier Ltd  2017
    In discussions related to reliability optimization using redundancy allocation, one of the structures that has attracted the attention of many researchers, is series-parallel structure. In models previously presented for reliability optimization of series-parallel systems, there is a restricting assumption based on which all components of a subsystem must be homogeneous. This constraint limits system designers in selecting components and prevents achieving higher levels of reliability. In this paper, a new model is proposed for reliability optimization of series-parallel systems, which makes possible the use of non-homogeneous components in each subsystem. As a result of this flexibility,... 

    A new method for computation the success probability of coverage for switch unit in the switching systems

    , Article International Journal of Engineering Transactions C: Aspects ; Volume 33, Issue 12 , 2020 , Pages 2509-2513 Yaghoubi, A ; Gholami, P ; Sharif University of Technology
    Materials and Energy Research Center  2020
    Redundancy technique is used to improve performance and achieving to increase the lifetime of a system. Nowadays, the redundancy method is applied in many industries. One of the common methods of redundancy is its utilization in the switching systems. In switching systems, one or more components are considered active mode and the others in the standby state to be used by switch if necessary. In order to be fully utilized all the components in the redundant device, the switch unit must perform its function, such as switching, perfectly. Successful coverage by switch unit is expressed with a probability. In this paper, a new approach to the likelihood of switch success is proposed, and showing... 

    A new approach in system reliability evaluation, shortest path of E-networks

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 28, Issue 2 B , 2004 , Pages 191-199 ; 03601307 (ISSN) Azaron, A ; Modarres, M ; Sharif University of Technology
    By applying shortest path analysis in stochastic networks, we introduce a new approach to obtain the reliability function of time-dependent systems. We assume that not all elements of the system are set to function from the beginning. Upon the failure of each element of the active path in the reliability graph, the system switches to the next path. Then, the corresponding elements are activated, and consequently, the connection between the input and the output is established. It is also assumed that each element exhibits a constant hazard rate and its lifetime is a random variable with exponential distribution. To evaluate the system reliability, we construct a directed stochastic network... 

    CLB-based detection and correction of bit-flip faults in SRAM-based FPGAs

    , Article 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007, New Orleans, LA, 27 May 2007 through 30 May 2007 ; 2007 , Pages 3696-3699 ; 02714310 (ISSN) Zarandi, H. R ; Miremadi, S. G ; Argyrides, C ; Pradhan, D. K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2007
    This paper presents a bit-flip tolerance in SRAM-based FPGAs which suffers from high energy particles, alpha and neutrons in the atmosphere. For each of protections, the applicability, efficiency and implementation issues are discussed. Moreover, the area, the power and the protection capability of the methods are mentioned and compared with previous work Based on the results of experiments and their analysis, one method is selected as best one. The selected method is much better than previous work e.g., duplication with comparison, triple modular redundancy which impose two and three area and power overheads, respectively. © 2007 IEEE  

    Redundancy allocation problem of a system with three-state components: A genetic algorithm

    , Article International Journal of Engineering, Transactions B: Applications ; Vol. 27, Issue. 11 , 2014 , pp. 1663-1672 ; ISSN: 1663-1672 Pourkarim Guilani, P ; Sharifi, M ; Niaki, S. T. A ; Zaretalab, A ; Sharif University of Technology
    The redundancy allocation is one of the most important and useful problems in system optimization, especially in electrical and mechanical systems. The object of this problem is to maximize system reliability or availability within a minimum operation cost. Many works have been proposed in this area so far to draw the problem near to real-world situations. While in classic models the system components are assumed to have two states of working and failed, in this paper, parallel components of serial sub-systems are considered to work in three states, each with a certain performance rate. The component states are classified into two working states of working with full performance and working... 

    A low-overhead and reliable switch architecture for Network-on-Chips

    , Article Integration, the VLSI Journal ; Volume 43, Issue 3 , June , 2010 , Pages 268-278 ; 01679260 (ISSN) Patooghy, A ; Miremadi, S. G ; Fazeli, M ; Sharif University of Technology
    This paper proposes and evaluates Low-overhead, Reliable Switch (LRS) architecture to enhance the reliability of Network-on-Chips (NoCs). The proposed switch architecture exploits information and hardware redundancies to eliminate retransmission of faulty flits. The LRS architecture creates a redundant copy of each newly received flit and stores the redundant flit in a duplicated flit buffer that is associated with the incoming channel of the flit. Flit buffers in the LRS are equipped with information redundancy to detect probable bit flip errors. When an error is detected in a flit buffer, its duplicated buffer is used to recover the correct value of the flit. In this way, the propagation... 

    Redundancy allocation problem of a system with increasing failure rates of components based on Weibull distribution: A simulation-based optimization approach

    , Article Reliability Engineering and System Safety ; Volume 152 , 2016 , Pages 187-196 ; 09518320 (ISSN) Pourkarim Guilani, P ; Azimi, P ; Akhavan Niaki, S. T ; Akhavan Niaki, S. A ; Sharif University of Technology
    Elsevier Ltd 
    The redundancy allocation problem (RAP) is a useful method to enhance system reliability. In most works involving RAP, failure rates of the system components are assumed to follow either exponential or k-Erlang distributions. In real world problems however, many systems have components with increasing failure rates. This indicates that as time passes by, the failure rates of the system components increase in comparison to their initial failure rates. In this paper, the redundancy allocation problem of a series-parallel system with components having an increasing failure rate based on Weibull distribution is investigated. An optimization method via simulation is proposed for modeling and a... 

    Weighted two-valued digit-set encodings: Unifying efficient hardware representation schemes for redundant number systems

    , Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 52, Issue 7 , 2005 , Pages 1348-1357 ; 10577122 (ISSN) Jaberipur, G ; Parhami, B ; Ghodsi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2005
    We introduce the notion of two-valued digit (twit) as a binary variable that can assume one of two different integer values. Posibits, or simply bits, in {0, 1} and negabits in {-1, 0}, commonly used in two's-complement representations and (n, p) encoding of binary signed digits, are special cases of twits. A weighted bit-set (WBS) encoding, which generalizes the two's-complement encoding by allowing one or more posibits and/or negabits in each radix-2 position, has been shown to unify many efficient implementations of redundant number systems. A collection of equally weighted twits, including ones with non-contiguous values (e.g., {-1, 1} or {0, 2}), can lead to wider representation range... 

    A four-phase algorithm to improve reliability in series-parallel systems with redundancy allocation

    , Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 1072-1082 Ghafarian Salehi Nezhad, A ; Eshraghniaye Jahromi A ; Salmani, M. H ; Ghasemi, F ; Sharif University of Technology
    In general, reliability is the ability of a system to perform and maintain its functions in routine, as well as hostile or unexpected, circumstances. The Redundancy Allocation Problem (RAP) is a combinatorial problem which maximizes system reliability by discrete simultaneous selection from available components. The main purpose of this study is to develop an effective approach to solve RAP, expeditiously. In this study, the basic assumption is considering Erlang distribution density for component failure rates. Another assumption is that each subsystem can have one of cold-standby or active redundancy strategies. The RAP is a NP-Hard problem which cannot be solved in reasonable time using... 

    The robust redundancy allocation problem in series-parallel systems with budgeted uncertainty

    , Article IEEE Transactions on Reliability ; Vol. 63, issue. 1 , February , 2014 , p. 239-250 ; 00189529 Feizollahi, M. J ; Ahmed, S ; Modarres, M ; Sharif University of Technology
    We propose a robust optimization framework to deal with uncertain component reliabilities in redundancy allocation problems in series-parallel systems. The proposed models are based on linearized versions of standard mixed integer nonlinear programming (MINLP) formulations of these problems. We extend the linearized models to address uncertainty by assuming that the component reliabilities belong to a budgeted uncertainty set, and develop robust counterpart models. A key challenge is that, because the models involve nonlinear functions of the uncertain data, classical robust optimization approaches cannot apply directly to construct their robust optimization counterparts. We exploit problem... 

    Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators

    , Article Robotica ; Volume 31, Issue 7 , 2013 , Pages 1073-1084 ; 02635747 (ISSN) Motahari, A ; Zohoor, H ; Korayem, M. H ; Sharif University of Technology
    Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators is a new practical problem in robotics. The problem concerns with determining the type of each manipulator module from among several specific types, so that the manipulator could reach several specified target frames with the lowest error. This paper suggests using a breadth-first search method and a workspace mean frame to solve this problem. To reduce errors, two heuristic ideas are proposed: two-by-two searching method and iteration. The effectiveness of the proposed method is verified through several numerical problems  

    Efficient energy-aware routing with redundancy elimination

    , Article IEEE Journal on Selected Areas in Communications ; Volume 33, Issue 12 , 2015 , Pages 2815-2825 ; 07338716 (ISSN) Omidvar, N ; Tsang, D. H. K ; Pakravan, M. R ; Lau, V. K. N ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Energy-Aware routing is a promising technique for reducing energy consumption in future networks. Under this scheme, traffic loads are aggregated over a subset of the network links, allowing other links to be turned off to save energy. Since the capacity of links is the main limiting constraint in this problem, to further improve energy saving, the idea of using redundancy elimination (RE) in energy-Aware routing has been proposed. As performing RE in routers consumes some energy, it should be specified, which routers should perform RE and which links should be deactivated so that the total energy consumption of the network is minimized. As a result, the problem of energy-Aware routing with... 

    LEXACT: low energy n-modular redundancy using approximate computing for real-time multicore processors

    , Article IEEE Transactions on Emerging Topics in Computing ; 2017 ; 21686750 (ISSN) Baharvand, F ; Ghassem Miremadi, S ; Sharif University of Technology
    Multicore processors are becoming popular in safety-critical applications. A series of these applications comprises of kernels where inexact computations may produce results within the boundary of sufficient quality though, for which the reliability should stay at the maximum possible level. Intrinsic core-level redundancy in multicore processors can be leveraged to achieve the desired reliability level in form of N-modular redundancy (NMR). While NMR provides a proactive means of reliability for critical systems, it has two main drawbacks: Increase in the area and energy consumption that are both limiting factors in the embedded systems. This paper presents a software-based method to... 

    A computationally efficient algorithm to find time-optimal trajectory of redundantly actuated robots moving on a specified path

    , Article Robotica ; 2018 ; 02635747 (ISSN) Mansouri, S ; Sadigh, M. J ; Fazeli, M ; Sharif University of Technology
    Cambridge University Press  2018
    time-optimal problem for redundantly actuated robots moving on a specified path is a challenging problem. Although the problem is well explored and there are proposed solutions based on phase plane analysis, there are still several unresolved issues regarding calculation of solution curves. In this paper, we explore the characteristics of the maximum velocity curve and propose an efficient algorithm to establish the solution curve. Then we propose a straightforward method to calculate the maximum or minimum possible acceleration on the path based on the pattern of saturated actuators, which substantially reduces the computational cost. Two numerical examples are provided to illustrate the... 

    A simple transport protocol for wireless sensor networks

    , Article 2005 Intelligent Sensors, Sensor Networks and Information Processing Conference, Melbourne, 5 December 2005 through 8 December 2005 ; Volume 2005 , 2005 , Pages 127-131 ; 0780393996 (ISBN); 9780780393998 (ISBN) Mansouri, V. S ; Afsari, B ; Shahmansouri, H ; ARC Research Networks on Intelligent Sensors,; Australian Government, Australian Research Council ; Sharif University of Technology
    IEEE Computer Society  2005
    In this paper, a new transport layer method is proposed utilizing a diversity scheme to make an end to end communication reliable and consequently reduce power consumption in large scale sensor networks. Sensor networks are composed of large number of battery powered nodes. Energy consumption is the most important design objective in sensor networks while delay and throughput are taken less into account. Wireless transmission is the other important characteristic of these networks. Small-scale fading decreases wireless communication performance. In a fading channel higher SNRs is needed and consequently more energy is consumed. In addition to error occurred because of poor communication... 

    Energy efficient SEU-tolerance in DVS-enabled real-time systems through information redundancy

    , Article 2005 International Symposium on Low Power Electronics and Design, San Diego, CA, 8 August 2005 through 10 August 2005 ; 2005 , Pages 281-286 ; 15334678 (ISSN) Ejlali, A ; Al-Hashimi, B. M ; Miremadi, S. G ; Schmitz, M. T ; Rosinger, P ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2005
    Concerns about the reliability of real-time embedded systems that employ dynamic voltage scaling has recently been highlighted [1,2,3], focusing on transient-fault-tolerance techniques based on time-redundancy. In this paper we analyze the usage of information redundancy in DVS-enabled systems with the aim of improving both the system tolerance to transient faults as well as the energy consumption. We demonstrate through a case study that it is possible to achieve both higher fault-tolerance and less energy using a combination of information and time redundancy when compared with using time redundancy alone. This even holds despite the impact of the information redundancy hardware overhead...