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    Designing a dynamic buyer-supplier coordination model in electronic markets using stochastic petri nets

    , Article International Journal of Information Systems and Supply Chain Management ; Volume 1, Issue 3 , 2008 , Pages 1-20 ; 19355726 (ISSN) Mahdavi, I ; Mohebbi, S ; Cho, N ; Paydar, M. M ; Mahdavi Amiri, N ; Sharif University of Technology
    2008
    Abstract
    Functional relationship between supplier and buyer in an open market place leads to investigate the role of both quantifiable and non-quantifiable parameters in coordination mechanism with the aim of achieving higher performance in supply chain activities. Here, we develop a supply chain model and a new agent to analyze and simulate the players' behavior in the network. A cooperative game theory framework is utilized between buyer and supplier in order to increase the supply chain performance. The study is supported by presenting SC Net Optimizer as a tool for implementing the proposed coordination mechanism and evaluates the performance of the chain by simulation using stochastic Petri nets... 

    A multiobjective integrated multiproject scheduling and multiskilled workforce assignment model considering learning effect under uncertainty

    , Article Computational Intelligence ; Volume 36, Issue 1 , February , 2020 , Pages 276-296 Hematian, M ; Seyyed Esfahani, M. M ; Mahdavi, I ; Mahdavi Amiri, N ; Rezaeian, J ; Sharif University of Technology
    Blackwell Publishing Inc  2020
    Abstract
    Today, organizations try to decline academically expenses using humans and resources in addition to rising managers and operators' satisfaction. Meantime, a very important step in the process of decision is the assignment of human resources, particularly in connection with research and development (R&D) projects in which the system is highly dependent on the capabilities of human resources. In this study, we tried all the assumptions that come true in the real world, considered a model for applied R&D projects to reduce costs and increase the efficiency of projects. Therefore, an integrated multiproject scheduling and multiskill human resource assignment model under uncertainty has developed... 

    An optimal natural-gas network using minimum spanning tree

    , Article 40th International Conference on Computers and Industrial Engineering: Soft Computing Techniques for Advanced Manufacturing and Service Systems, CIE40 2010, 25 July 2010 through 28 July 2010 ; July , 2010 ; 9781424472956 (ISBN) Mahdavi, I ; Mohajeri, A ; Arabmaghsudi, M ; Yahyanejad, M. H ; Taghipourian, F ; Mahdavi Amiri, N ; Sharif University of Technology
    2010
    Abstract
    We consider the design of an optimal natural-gas network. Our proposed network contains two echelons, Town Broad Stations (TBSs), and consumers (demand zones). Here, our aim is a two-stage cost minimization. We first determine locations of the TBS so that the location-allocation cost is minimized. Then, we show how to distribute the flow of gas among the TBS minimizing the flow cost by using Minimum Spanning Tree (MST). A case study in Mazandaran Gas Company in Iran is made to assess the validity and effectiveness of our proposed model  

    Agent-based web service for the design of a dynamic coordination mechanism in supply networks

    , Article Journal of Intelligent Manufacturing ; Volume 20, Issue 6 , 2009 , Pages 727-749 ; 09565515 (ISSN) Mahdavi, I ; Mohebbi, S ; Zandakbari, M ; Cho, N ; Mahdavi Amiri, N ; Sharif University of Technology
    2009
    Abstract
    The theory of network coordination presents an effective approach to improve the business processes within supply networks. The automation of the negotiation process among buyers and suppliers has become an important policy in the transactional networks. This leads to assessing the roles of both quantifiable and non-quantifiable parameters in coordination mechanisms with the aim of achieving higher performance. Here, we develop an e-based supply chain multi-agent model for the design of mass-customized on-line services. The model addresses the bullwhip effect in multi-stage supply chain and also clarifies the evaluation of inventory policies in various supply and demand uncertainties. To... 

    A model for the time dependent vehicle routing problem with time windows under traffic conditions with intelligent travel times

    , Article RAIRO - Operations Research ; Volume 55, Issue 4 , 2021 , Pages 2203-2222 ; 03990559 (ISSN) Khanchehzarrin, S ; Shahmizad, M ; Mahdavi, I ; Mahdavi Amiri, N ; Ghasemi, P ; Sharif University of Technology
    EDP Sciences  2021
    Abstract
    A new mixed-integer nonlinear programming model is presented for the time-dependent vehicle routing problem with time windows and intelligent travel times. The aim is to minimize fixed and variable costs, with the assumption that the travel time between any two nodes depends on traffic conditions and is considered to be a function of vehicle departure time. Depending on working hours, the route between any two nodes has a unique traffic parameter. We consider each working day to be divided into several equal and large intervals, termed as a time interval of traffic. Here, allowing for long distances between some of the nodes, travel time may take more than one time interval of traffic,... 

    Data envelopment analysis based comparison of two hybrid multi-criteria decision-making approaches for mobile phone selection: a case study in Iranian telecommunication environment

    , Article International Journal of Information and Decision Sciences ; Volume 1, Issue 2 , 2008 , Pages 194-220 ; 17567017 (ISSN) Mahdavi, I ; Fazlollahtabar, H ; Mozaffari, E ; Heidari, M ; Mahdavi Amiri, N ; Sharif University of Technology
    2008
    Abstract
    The arrival of the mobile phone and its rapid and widespread growth may well be seen as one of the most significant developments in the fields of communication and information technology over the past two decades. The aim of this study is to compare two hybrid multi-criteria decision-making (MCDM) approaches to evaluate the mobile phone options with respect to user’s preferences. Firstly, we identify the most desirable features influencing the choice of a mobile phone. This is realised through a survey conducted among the target group, the experiences of the telecommunication sector experts and the studies in the literature. Secondly, two MCDM methods are used in the evaluation procedure.... 

    Ultra high-throughput architectures for hard-output MIMO detectors in the complex domain

    , Article Midwest Symposium on Circuits and Systems, 7 August 2011 through 10 August 2011l ; August , 2011 ; 15483746 (ISSN) ; 9781612848570 (ISBN) Mahdavi, M ; Shabany, M ; Sharif University of Technology
    2011
    Abstract
    In this paper, a novel hard-output detection algorithm for the complex multiple-input multiple-output (MIMO) detectors is proposed, which results in a significant throughput enhancement, a near-ML performance, and an SNR-independent fixed-throughput. Moreover, a high-throughput VLSI implementation is proposed, which is based on a novel method of the node generation and sorting scheme. The proposed design achieves the throughput of 10Gbps in a 0.13 μ CMOS process, which is the highest throughput reported in the literature for both the real and the complex domains. Synthesis results in 90nm CMOS also show that the proposed scheme can achieve the throughput of up to 15Gbps. Moreover, the FPGA... 

    Novel MIMO detection algorithm for high-order constellations in the complex domain

    , Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 21, Issue 5 , 2013 , Pages 834-847 ; 10638210 (ISSN) Mahdavi, M ; Shabany, M ; Sharif University of Technology
    2013
    Abstract
    A novel detection algorithm with an efficient VLSI architecture featuring efficient operation over infinite complex lattices is proposed. The proposed design results in the highest throughput, the lowest latency, and the lowest energy compared to the complex-domain VLSI implementations to date. The main innovations are a novel complex-domain means of expanding/visiting the intermediate nodes of the search tree on demand, rather than exhaustively, as well as a new distributed sorting scheme to keep track of the best candidates at each search phase. Its support of unbounded infinite lattice decoding distinguishes the present method from previous K-Best strategies and also allows its complexity... 

    A 13 Gbps, 0.13 μm CMOS, multiplication-free MIMO detector

    , Article Journal of Signal Processing Systems ; Volume 88, Issue 3 , 2017 , Pages 273-285 ; 19398018 (ISSN) Mahdavi, M ; Shabany, M ; Sharif University of Technology
    2017
    Abstract
    A novel ultra high-throughput detection algorithm with an efficient VLSI architecture for high-order MIMO detectors in the complex constellations is proposed. The main contributions include a new method for the node generation in complex-domain, pipelinable sorters, and a simple combinational circuit instead of the conventional multipliers, which makes the proposed architecture multiplication-free. The proposed design achieves an SNR-independent throughput of 13.3 Gbps at the clock frequency of 556 MHz in a 0.13 μm CMOS technology with a near ML performance. The implemented design consumes 90 pJ per detected bit with the initial latency of 0.3 μs. Also, the synthesis results in a 90 nm CMOS... 

    A genetic algorithm for a creativity matrix cubic space clustering: A case study in Mazandaran Gas Company

    , Article Applied Soft Computing Journal ; Volume 13, Issue 4 , 2013 , Pages 1661-1673 ; 15684946 (ISSN) Aalaei, A ; Fazlollahtabar, H ; Mahdavi, I ; Mahdavi Amiri, N ; Yahyanejad, M. H ; Sharif University of Technology
    2013
    Abstract
    Creativity is a promoting factor in organizations. Having employees in structured and organized configurations in a creative manner, helps in improving the productivity. We investigate different structural aspects of teams' network organization and the creativity within a knowledge development program (KDP). The proposed methodology being equipped with a heuristic clustering technique, classifies the employees with respect to creativity parameters and configures a creativity matrix. Applying the creativity matrix, clustering is performed via mathematical programming. For large problems, a genetic algorithm (GA) is developed to solve the mathematical model. We also employ the Taguchi method... 

    A Hough based data association algorithm for target tracking

    , Article International Radar Symposium, IRS 2011 - Proceedings, 7 September 2011 through 9 September 2011 ; September , 2011 , Pages 623-628 ; 9783927535282 (ISBN) Mahdavi, A ; Moqiseh, A ; Nayebi, M. M ; Sharif University of Technology
    2011
    Abstract
    A new approach for tracking targets in TWS systems is introduced which is based on Hough transform. The main idea is to take target's velocity and course of motion as the main tracking quantities and calculate other kinematic parameters of the target from these two main parameters. The main criteria for associating targets to tracks in Data Association (DA) step is co linearity of targets with the history of track and Hough transform is the main tool in this step. Computer simulation results are presented to compare the performance of the suggested algorithm with the conventional tracking systems  

    A fast enhanced algorithm of PRI transform

    , Article Proceedings - 6th International Symposium on Parallel Computing in Electrical Engineering, PARELEC 2011, 4 April 2011 through 5 April 2011 ; April , 2011 , Pages 179-184 ; 9780769543970 (ISBN) Mahdavi, A ; Pezeshk, A. M ; Sharif University of Technology
    2011
    Abstract
    The problem of estimating pulse repetition interval (PRI) of an interleaved pulse train which consist of several independent radar signals, is the main issue of signal processing in electronic support systems. PRI Transform algorithm is one of the well known and effective methods of PRI detection which is capable of detecting several close jittered signals and surpassing subharmonics, but have some drawbacks especially because of small PRI dynamic range and heavy computations. In this paper a modified PRI transform is introduced which manage wide range of PRIs simultaneously, and speed up the algorithm by significantly reducing the computations. Moreover an efficient threshold is set for... 

    A Criterion for the Triviality of G(D) and Its Applications to the Multiplicative Structure of D

    , Article Communications in Algebra ; Volume 40, Issue 7 , 2012 , Pages 2645-2670 ; 00927872 (ISSN) Mahdavi Hezavehi, M ; Motiee, M ; Sharif University of Technology
    2012
    Abstract
    Let D be an F-central division algebra of index n. Here we present a criterion for the triviality of the group G(D) = D*/Nrd D/F(D*)D′ and thus generalizing various related results published recently. To be more precise, it is shown that G(D) = 1 if and only if SK 1(D) = 1 and F *2 = F *2n. Using this, we investigate the role of some particular subgroups of D* in the algebraic structure of D. In this direction, it is proved that a division algebra D of prime index is a symbol algebra if and only if D* contains a non-abelian nilpotent subgroup. More applications of this criterion including the computation of G(D) and the structure of maximal subgroups of D* are also investigated  

    Division Algebras with Radicable Multiplicative Groups

    , Article Communications in Algebra ; Volume 39, Issue 11 , 2011 , Pages 4084-4096 ; 00927872 (ISSN) Mahdavi Hezavehi, M ; Motiee, M ; Sharif University of Technology
    2011
    Abstract
    Given a divisible finite field extension K/F, the structure of Br(F), the Brauer group of F, is investigated. It is shown that, if F is indivisible, then Br(F) ≅ ℤ 2, which generalizes the Frobenius Theorem. As a consequence, when F is indivisible, the class of all finite dimensional non-commutative F-central division algebras D having radicable multiplicative groups D* is determined. In fact, it is proved that the following statements are equivalent: (1) D is radicable, (2) D contains a divisible subfield K/F, and (3) D is the ordinary quaternion division algebra and F(√-1) is divisible  

    A robust method for PRI modulation recognition

    , Article 2010 IEEE 10th International Conference on Signal Processing, ICSP2010, Beijing, China, 24 October 2010 through 28 October 2010 ; October , 2010 , Pages 1873-1876 ; 9781424458981 (ISBN) Mahdavi, A ; Pezeshk, A. M ; Sharif University of Technology
    2010
    Abstract
    one of the main problems of radar identification in electronic warfare support system is analysis of pulse repetition interval (PRI) modulation. In this paper a robust method of recognizing the PRI modulation type of radar signals is proposed to improve robustness of previous recognition methods as well as to reduce the complexity. Simulation results show that the proposed method achieves much better error recognition rate in case of missing and spurious pulses than other methods such as autocorrelation based techniques and the Noone method  

    An adaptive competitive penalty method for nonsmooth constrained optimization

    , Article Numerical Algorithms ; 2016 , Pages 1-32 ; 10171398 (ISSN) Mahdavi Amiri, N ; Shaeiri, M ; Sharif University of Technology
    Springer New York LLC  2016
    Abstract
    We present a competitive algorithm to minimize a locally Lipschitz function constrained with locally Lipschitz constraints. The approach is to use an ℓ1 nonsmooth penalty function. The method generates second order descent directions to minimize the ℓ1 penalty function. We introduce a new criterion to decide upon acceptability of a Goldstein subdifferential approximation. We show that the new criterion leads to an improvement of the Goldstein subdifferential approximation, as introduced by Mahdavi-Amiri and Yousefpour. Also, making use of our proposed line search strategy, the method always moves on differentiable points. Furthermore, the method has an adaptive behaviour in the sense that,... 

    An adaptive competitive penalty method for nonsmooth constrained optimization

    , Article Numerical Algorithms ; Volume 75, Issue 1 , 2017 , Pages 305-336 ; 10171398 (ISSN) Mahdavi Amiri, N ; Shaeiri, M ; Sharif University of Technology
    Springer New York LLC  2017
    Abstract
    We present a competitive algorithm to minimize a locally Lipschitz function constrained with locally Lipschitz constraints. The approach is to use an ℓ1 nonsmooth penalty function. The method generates second order descent directions to minimize the ℓ1 penalty function. We introduce a new criterion to decide upon acceptability of a Goldstein subdifferential approximation. We show that the new criterion leads to an improvement of the Goldstein subdifferential approximation, as introduced by Mahdavi-Amiri and Yousefpour. Also, making use of our proposed line search strategy, the method always moves on differentiable points. Furthermore, the method has an adaptive behaviour in the sense that,... 

    Clearing an orthogonal polygon to find the evaders

    , Article Theoretical Computer Science ; Volume 847 , December , 2020 , Pages 175-184 Mahdavi, S. S ; Ghodsi, M ; Sharif University of Technology
    Elsevier B. V  2020
    Abstract
    In a multi-robot system, a number of autonomous robots would sense, communicate, and decide to move within a given domain to achieve a common goal. In the pursuit-evasion problem, a polygonal region is given and a robot called a pursuer tries to find some mobile targets called evaders. The goal of this problem is to design a motion strategy for the pursuer such that it can detect all the evaders. In this paper, we consider a new variant of the pursuit-evasion problem in which the robots (pursuers) each moves back and forth along an orthogonal line segment inside a simple orthogonal polygon P. We assume that P includes unpredictable, moving evaders that have bounded speed. We propose the... 

    A conjugate gradient sampling method for nonsmooth optimization

    , Article 4OR ; Volume 18, Issue 1 , May , 2020 , Pages 73-90 Mahdavi Amiri, N ; Shaeiri, M ; Sharif University of Technology
    Springer  2020
    Abstract
    We present an algorithm for minimizing locally Lipschitz functions being continuously differentiable in an open dense subset of Rn. The function may be nonsmooth and/or nonconvex. The method makes use of a gradient sampling method along with a conjugate gradient scheme. To find search directions, we make use of a sequence of positive definite approximate Hessians based on conjugate gradient matrices. The algorithm benefits from a restart procedure to improve upon poor search directions or to make sure that the approximate Hessians remain bounded. The global convergence of the algorithm is established. An implementation of the algorithm is executed on a collection of well-known test problems.... 

    Pure sulfide Cu2ZnSnS4 layers through a one-step low-temperature PLD technique: Insight into simulation on modified back contact to overcome the barrier of MoS2

    , Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 262 , 2020 Heidariramsheh, M ; Haghighi, M ; Dabbagh, M. M ; Mahdavi, S. M ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Targeting on the selenium free, pure sulfide kesterite compound (CZTS) allows retention of the higher band gap nontoxic absorber for a single-junction solar cell. In this work, CZTS thin films were deposited by the PLD method and the Structural/optical properties, as well as Mott–Schottky analysis, were studied at different substrate temperatures. Without undergoing the sulfurization process, the single-phase CZTS thin film is prepared at 300 ℃. In the second step, a numerical simulation is performed using the solar cell capacitance simulator to study the effect of the grading layer of MoS(Se)2 on the rear side of pure sulfide kesterite based solar cells. The device with a MoSe2 coated...