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    A bi-objective model for scheduling of multiple projects under multi-skilled workforce for distributed load energy usage

    , Article Operational Research ; 2021 ; 11092858 (ISSN) Javanmard, S ; Afshar Nadjafi, B ; Taghi Akhavan Niaki, S ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    Satisfying the clients' uncompromising priorities is a challenge for decision makers of organizations that face multiple projects. This paper considers an organization with a multi-skilled workforce working on several predetermined projects under time-of-use energy tariffs where distributed load energy usage is the primary concern of energy suppliers. This paper also considers different time-of-use energy tariffs, which are among the most common strategies to reach a more balanced energy utilization. The problem is stated as a bi-objective mixed-integer programming model containing two conflicting objectives; to minimize the total cost of the multi-skilled workforce and obtain a sustainable... 

    A bi-objective model for scheduling of multiple projects under multi-skilled workforce for distributed load energy usage

    , Article Operational Research ; Volume 22, Issue 3 , 2022 , Pages 2245-2280 ; 11092858 (ISSN) Javanmard, S ; Afshar Nadjafi, B ; Taghi Akhavan Niaki, S ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    Satisfying the clients' uncompromising priorities is a challenge for decision makers of organizations that face multiple projects. This paper considers an organization with a multi-skilled workforce working on several predetermined projects under time-of-use energy tariffs where distributed load energy usage is the primary concern of energy suppliers. This paper also considers different time-of-use energy tariffs, which are among the most common strategies to reach a more balanced energy utilization. The problem is stated as a bi-objective mixed-integer programming model containing two conflicting objectives; to minimize the total cost of the multi-skilled workforce and obtain a sustainable... 

    EACHP: Energy Aware Clustering Hierarchy Protocol for Large Scale Wireless Sensor Networks

    , Article Wireless Personal Communications ; Volume 85, Issue 3 , December , 2015 , Pages 765-789 ; 09296212 (ISSN) Barati, H ; Movaghar, A ; Rahmani, A. M ; Sharif University of Technology
    Springer New York LLC  2015
    Abstract
    Wireless sensor networks (WSNs) comprise a large number of small sensor nodes scattered across limited geographical areas. The nodes in such networks carry sources of limited and mainly unchangeable energy. Therefore, it is necessary that these networks operate under energy efficient protocols and structures. Energy efficient clustering algorithms have been developed to reduce the networks energy consumption and extend its lifetime. This paper presents an innovative cluster-based communication protocol for WSNs. In order to reduce communication overhead, the authors propose an Energy Aware Clustering Hierarchy Protocol that creates a multi-level hierarchical structure to adequately route and... 

    Reliable and energy-efficient routing for green software defined networking

    , Article 9th International Symposium on Telecommunication, IST 2018, 17 December 2018 through 19 December 2018 ; 2019 , Pages 221-226 ; 9781538682746 (ISBN) Norouzi, A ; Majidi, B ; Movaghar, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Improvement of energy efficiency in Software Defined Networking (SDN) is a challenging problem. In order to achieve higher energy efficiency, the routing and scheduling in software defined networks should be planned robustly based on the topological specifications of the SDN. The topological specifications of the SDN depends on the size of the network graph which changes rapidly as the virtualized network devices in the network turned on and off by the controller. Therefore, modelling the SDN graph is an important issue in designing a reliability aware energy efficient SDN. In this paper we propose a new algorithm for reliable energy efficient traffic engineering in SDN. In the proposed... 

    COACH: Consistency aware check-pointing for nonvolatile processor in energy harvesting systems

    , Article IEEE Transactions on Emerging Topics in Computing ; 2019 ; 21686750 (ISSN) Hoseinghorban, A ; Hosseini Hosseini Monazzah, A. M ; Bazzaz, M ; Safaei, B ; Ejlali, A ; Sharif University of Technology
    IEEE Computer Society  2019
    Abstract
    Recently, energy harvesting systems that utilize hybrid NVM-SRAM memory in their designs are introduced as a promising alternative for battery-operated systems. Since the ambient input power of an energy harvesting system fluctuates as the environmental conditions change, the system may stop the execution of programs until it receives enough energy to continue the execution. Resuming the execution of a program after the suspension may lead to data inconsistency in an energy harvesting system and threatens the correct functionality of the programs. In this paper, we propose COACH, an energy-efficient consistency-aware memory scheme which guarantees the correct functionality and consistency of... 

    COACH: Consistency aware check-pointing for nonvolatile processor in energy harvesting systems

    , Article IEEE Transactions on Emerging Topics in Computing ; 2019 ; 21686750 (ISSN) Hoseinghorban, A ; Hosseini Monazzah, A. M. H ; Bazzaz, M ; Safaei, B ; Ejlali, A ; Sharif University of Technology
    IEEE Computer Society  2019
    Abstract
    Recently, energy harvesting systems that utilize hybrid NVM-SRAM memory in their designs are introduced as a promising alternative for battery-operated systems. Since the ambient input power of an energy harvesting system fluctuates as the environmental conditions change, the system may stop the execution of programs until it receives enough energy to continue the execution. Resuming the execution of a program after the suspension may lead to data inconsistency in an energy harvesting system and threatens the correct functionality of the programs. In this paper, we propose COACH, an energy-efficient consistency-aware memory scheme which guarantees the correct functionality and consistency of... 

    Modeling of Phase Change Materials Operating in Energy Efficient Buildings

    , M.Sc. Thesis Sharif University of Technology Kayedpour, Kamran (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Zabihollah, Abolghasem (Co-Advisor)
    Abstract
    Shortage of energy sources in the new decade along with the increasing level of greenhouse gas emissions urges researchers in the field of energy to explore for the new source of energy as well as seeking for methods for usage of available energy resources more efficiently. Therefore, development of building with low level of energy usage may significantly reduce the need for grid energy. This can be met with new construction materials to reduce the energy consumption, using renewable energies sources such as solar and wind as well as design and development of materials with capability to store energy. The use of materials which can store energy and release it when needed has been considered... 

    Energy efficient all-optical arbitration in optical network-on-chip

    , Article 2012 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2012 ; 2012 ; 9781467302623 (ISBN) Koohi, S ; Yin, Y ; Hessabi, S ; Yoo, S. J. B ; Sharif University of Technology
    2012
    Abstract
    We propose an all-optical arbitration architecture to resolve end-point contention in the optical networks-on-chip. The proposed architecture reduces on-chip optical power and energy losses by 37% and 21%, respectively, compared to Corona's token-based control plane  

    Low-power bottom-plate sampling capacitor-splitting DAC for SAR ADCs

    , Article Electronics Letters ; Volume 52, Issue 11 , 2016 , Pages 913-915 ; 00135194 (ISSN) Yazdani, B ; Khorami, A ; Sharifkhani, M ; Sharif University of Technology
    Institution of Engineering and Technology  2016
    Abstract
    A highly energy-efficient switching method for capacitor-splitting digital-to-analogue converter (DAC) in successive approximation register (SAR) analogue-to-digital converters (ADCs) is presented. In the proposed DAC, a bottom-plate sampling method is introduced which requires only one reference voltage (Vcm = 1/2Vref) during the entire DAC switching steps. Therefore, in addition to the switching energy reduction, the precision of the DAC is increased since only one reference voltage is used. The DAC average switching energy and the area are reduced by 98.44% and 50% compared with the conventional binary weighted DAC  

    COACH: Consistency aware check-pointing for nonvolatile processor in energy harvesting systems

    , Article IEEE Transactions on Emerging Topics in Computing ; Volume 9, Issue 4 , December , 2021 , Pages 2076-2088 ; 21686750 (ISSN) Hosseinghorban, A ; Hosseini Monazzah, A. M ; Bazzaz, M ; Safaei, B ; Ejlali, A ; Sharif University of Technology
    IEEE Computer Society  2021
    Abstract
    Recently, energy harvesting systems that utilize hybrid NVM-SRAM memory in their designs are introduced as a promising alternative for battery-operated systems. Since the ambient input power of an energy harvesting system fluctuates as the environmental conditions change, the system may stop the execution of programs until it receives enough energy to continue the execution. Resuming the execution of a program after the suspension may lead to data inconsistency in an energy harvesting system and threatens the correct functionality of the programs. In this article, we propose COACH, an energy-efficient consistency-aware memory scheme which guarantees the correct functionality and consistency... 

    Study on control input energy efficiency of fractional order control systems

    , Article IEEE Journal on Emerging and Selected Topics in Circuits and Systems ; Volume 3, Issue 3 , July , 2013 , Pages 475-482 ; 21563357 (ISSN) Tavakoli Kakhki, M ; Haeri, M ; Tavazoei, M. S ; Sharif University of Technology
    2013
    Abstract
    Control input energy efficiency is an important issue which should be considered in designing any control system. Due to the importance of this subject, in the present paper fractional order control systems are studied in the viewpoint of control input energy efficiency. In this study, the divergent terms of the control input energy function of fractional order control systems are obtained. It is shown that these terms have a significant role in the amount of the energy injected to the plant by the controller. Finally, two examples are provided to demonstrate the usefulness of the presented results in the paper  

    An energy efficient refractive structure for energy concentration on PV cells

    , Article 2010 IEEE International Energy Conference and Exhibition, EnergyCon 2010, 18 December 2010 through 22 December 2010, Manama ; 2010 , Pages 648-651 ; 9781424493807 (ISBN) Kavehvash, Z ; Rajaii, M ; Birjandi, A. M ; Gholamrezaei, H ; Gholamrezaei, A ; Sharif University of Technology
    2010
    Abstract
    In this paper a novel refractive structure for increasing the performance of photovoltaic cells1 is proposed. This structure which is named back-to-back-Fresnel lens is similar to conventional Fresnel lens used for energy concentration on PV cells while comprising some superior features. Among these features is its thinness, just like Fresnel lens, and lower loss of energy and simpler structure and design compared to a Fresnel lens with similar properties. The proposed lens is experimentally tested with a PV cell while the obtained results confirm its superior features  

    Communication-awareness for energy-efficiency in datacenters

    , Article Energy Efficiency in Data Centers and Clouds, 2016 ; Volume 100 , 2016 , Pages 201-254 ; 00652458 (ISSN) ; 9780128047781 (ISBN) Nabavinejad, S. M ; Goudarzi, M ; Sharif University of Technology
    Academic Press Inc  2016
    Abstract
    With the proliferation of cloud computing concept, the datacenters, as the basic infrastructure for cloud computing, have gained an ever-growing attention during the last decade. Energy consumption in datacenters is one of the several features of them that have been the target of various researches. Two major consumers of energy in datacenters are the cooling system and IT equipment. Computing resources, such as servers, and communicating ones, such as switches, constitute the main portion of IT equipment. Among these two major players, the servers have been considered more than networking equipment. Making servers energy proportional as well as server consolidation are the two essential... 

    Dynamic load management for a residential customer; Reinforcement Learning approach

    , Article Sustainable Cities and Society ; Volume 24 , 2016 , Pages 42-51 ; 22106707 (ISSN) Sheikhi, A ; Rayati, M ; Ranjbar, A. M ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    United Nation aims to double the global rate of improvement in energy efficiency as one of the sustainable development goals. It means researchers should focus on energy systems to enhance their overall efficiency. One of the effective solution to move from suboptimal energy systems to optimal ones is analyzing energy system in Energy Hub (EH) framework. In EH framework, interactions between different energy carriers are considered in supplying the required loads. The couplings and selecting proper combinations of inputs energy carriers lead to more optimized and intelligent consumption. The appropriate combination is found by solving an optimization problem at each time step. Utilizing... 

    Theoretical modeling and optimizing design of a packaged liquid chiller

    , Article 2007 ASME/JSME Thermal Engineering Summer Heat Transfer Conference, HT 2007, Vancouver, BC, 8 July 2007 through 12 July 2007 ; July , 2007 , Pages 527-537 ; 0791842746 (ISBN); 9780791842744 (ISBN) Heydari, A ; Kargar, S ; Sharif University of Technology
    2007
    Abstract
    This work attempts to develop a physical simulation model for the purpose of studying the effect of various design parameters on the performance of a packaged liquid chiller. A computer model which simulates the steady-state cyclic performance of a vapor compression chiller is developed for the purpose of performing detailed physical design analysis of actual industrial chillers. The model can be used for optimizing design and for detailed energy efficiency analysis of packaged liquid chillers. The simulation model takes into account presence of all chiller components such as compressor, shell-and-tube condenser and evaporator heat exchangers, thermostatic expansion valve and connection... 

    Utility constrained energy minimization in aloha networks

    , Article 2007 4th Annual IEEE Consumer Communications and Networking Conference, CCNC 2007, Las Vegas, NV, 11 January 2007 through 13 January 2007 ; January , 2007 , Pages 665-669 ; 1424406668 (ISBN); 9781424406661 (ISBN) Khodaian, A ; Hossein Khalaj, B ; Talebi, M. S ; Sharif University of Technology
    2007
    Abstract
    In this paper we consider the issue of energy efficiency in random access networks and show that optimizing transmission probabilities of nodes can enhance network performance in terms of energy consumption and fairness. First, we propose a heuristic power control method that improves throughput, and then we model the Utility Constrained Energy Minimization (UCEM) problem in which the utility constraint takes into account single and multi node performance. UCEM is modeled as a convex optimization problem and Sequential Quadratic Programming (SQP) is used to find optimal transmission probabilities. Numerical results show that our method can achieve fairness, reduce energy consumption and... 

    Evaluation of optimal occasional tilt on photovoltaic power plant energy efficiency and land use requirements, Iran

    , Article Sustainability (Switzerland) ; Volume 13, Issue 18 , 2021 ; 20711050 (ISSN) Fathi, A ; Bararzadeh Ledari, M ; Saboohi, Y ; Sharif University of Technology
    MDPI  2021
    Abstract
    The paper studies the optimum panel horizontal orientation angle toward the Sun and the optimum time interval of the panel’s movement. The optimum time intervals or panel movement can change the rate of input energy to the panel surface in Iran. For this purpose, a neural network has been trained to estimate the intensity of solar radiation in Iran. After model validation, the intensity of solar radiation has been estimated by selecting adequate geographical regions. Based on the intensity of sunlight, Iran has been divided into ten regions. In these regions, 40 cities have been randomly selected to study the effect of the panel’s angle variations within appropriate time inter-vals, as well... 

    Energy Efficient Software Defined Networks

    , M.Sc. Thesis Sharif University of Technology Daemi, Nafiseh (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Abstract
    With a growing concern on the considerable energy consumed by data centers, research efforts are targeting toward green data centers with higher energy efficiency. Networks are essential to today’s highly instrumented and connected society. Currently responsible for a fraction of the energy the IT sector consumes, networks rely on equipments that often use a constant amount of power regardless of their utilization; a worsening scenario as traffic is expected to increase by a factor of three in the next few years. Datacenter networks, for instance, employ devices that consume several kilowatts of power even when idle. This work aims to improve the energy efficiency of datacenter networks by... 

    Energy efficient and high speed error control scheme for real time wireless sensor networks

    , Article International Journal of Distributed Sensor Networks ; Vol. 2014 , 2014 Barati, A ; Movaghar, A ; Sabaei, M ; Sharif University of Technology
    Abstract
    Reliability and energy consumption are two of the main constraints in wireless sensor networks (WSNs). In this paper, a novel energy efficient and high speed error control scheme is introduced that is based on the Redundant Residue Number System (RRNS) allowing real-time application of WSNs. The proposed approach employs a new 3-moduli set {22n+1, 2 2n1-1, 2n- 1 } and an efficient reverse converter which relies on the Mixed Radix Conversion (MRC) algorithm and achieves significant improvements both in terms of conversion delay and hardware design. In order to obtain error controllability, two-redundant-moduli set 23n+1 - 1, 24n+1 - 1 is also added to the main 3-moduli set. The theoretical... 

    FOMA: Flexible overlay multi-path data aggregation in wireless sensor networks

    , Article Proceedings - IEEE Symposium on Computers and Communications, 1 July 2012 through 4 July 2012 ; July , 2012 , Pages 000508-000511 ; 15301346 (ISSN) ; 9781467327121 (ISBN) Ashouri, M ; Yousefi, H ; Hemmatyar, A. M. A ; Movaghar, A ; Sharif University of Technology
    IEEE  2012
    Abstract
    Data aggregation is an efficient method to conserve energy by reducing packet transmissions in WSNs. However, providing end-to-end data reliability is a major challenge when the network uses data aggregation. In this case, a packet loss can miss a complete subtree of values, thus greatly affecting the final results. Data transmission in multiple paths can tolerate this problem, but it may incur some computation errors for duplicate-sensitive aggregates. In this paper, we propose a Flexible Overlay Multi-path data Aggregation protocol (FOMA) which uses the available path redundancy to deliver a correct aggregate result to the sink with high reliability in an energy-efficient manner. It...