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Total 35 records

    Cause-and-effect relationships affecting distribution loss management

    , Article IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe, 11 October 2010 through 13 October 2010 ; October , 2010 ; 9781424485109 (ISBN) Ghofrani Jahromi, Z ; Ehsan, M ; Masjed Jamei, M ; Sharif University of Technology
    2010
    Abstract
    There are a lot of parameters which are decisive in distribution loss management, such as demand value, energy price, etc. In this paper the cause-and-effect relationships among some of these variables are clearly described. The study demonstrates how a variable in the model will change, if an alteration in one of the other variables occurs. The power system variables considered in this study include energy and loss prices, generation and demand values, distribution loss, distribution system age, number of customers connected to the smart grid, distribution network revenue, and so forth. The smart grid impacts can be studied from two different aspects: 1) the communication infrastructure... 

    A novel high-performance and low-power mesh-based NoC

    , Article IPDPS 2008 - 22nd IEEE International Parallel and Distributed Processing Symposium, Miami, FL, 14 April 2008 through 18 April 2008 ; 2008 ; 9781424416943 (ISBN) Sabbaghi Nadooshan, R ; Modarressi, M ; Sarbazi Azad, H ; Sharif University of Technology
    2008
    Abstract
    In this paper, a 2D shuffle-exchange based mesh topology, or 2D SEM (Shuffle-exchange Mesh) for short, is presented for network-on-chips. The proposed two-dimensional topology applies the conventional well-known shuffle-exchange structure in each row and each column of the network. Compared to an equal sized mesh which is the most common topology in on-chip networks, the proposed shuffle-exchange based mesh network has smaller diameter but for an equal cost. Simulation results show that the 2D SEM effectively reduces the power consumption and improves performance metrics of the on-chip networks with regard to the conventional mesh topology. ©2008 IEEE  

    A usage control based architecture for cloud environments

    , Article Proceedings of the 2012 IEEE 26th International Parallel and Distributed Processing Symposium Workshops, IPDPSW 2012, 21 May 2012 through 25 May 2012 ; 2012 , Pages 1534-1539 ; 9780769546766 (ISBN) Tavizi, T ; Shajari, M ; Dodangeh, P ; Sharif University of Technology
    2012
    Abstract
    Today modern computing systems leverage distributed models such as cloud, grid, etc. One of the obstacles of wide spreading these distributed computing models is security challenges which includes access control problem. These computing models because of providing features like on-demand self-service, ubiquitous network access, rapid elasticity and scalability, having dynamic infrastructure and offering measured service, need a powerful and continuous control over access and usage session. Usage control (UCON) model is emerged to cover some drawbacks of traditional access control models with features like attribute mutability and continuity of control. Several recent works have been done to... 

    Variation-aware server placement and task assignment for data center power minimization

    , Article Proceedings of the 2012 10th IEEE International Symposium on Parallel and Distributed Processing with Applications, ISPA 2012 ; 2012 , Pages 158-165 ; 9780769547015 (ISBN) Pahlavan, A ; Momtazpour, M ; Goudarzi, M ; Sharif University of Technology
    2012
    Abstract
    Size and number of data centers are fast growing all over the world and their increasing total power consumption is a worldwide concern. Moreover, increase in the amount of process variation in nanometer technologies and its effect on total power consumption of servers has made it inevitable to move toward variation-aware power reduction strategies. This paper formulates a variation-aware joint server placement and task assignment method using Integer Linear Programming (ILP) to minimize total power consumption of data centers. We first determine the optimum placement of servers in the data center racks based on total power consumption of each server and the data center recirculation model... 

    Broadcast algorithms on OTIS-Cubes

    , Article 2008 International Symposium on Parallel and Distributed Processing with Applications, ISPA 2008, Sydney, NSW, 10 December 2008 through 12 December 2008 ; December , 2008 , Pages 637-642 ; 9780769534718 (ISBN) Ebrahimi Kahaki, H ; Sarbazi Azad, H ; Sharif University of Technology
    2008
    Abstract
    OTIS-based architectures appear to have the potential to be an interesting option for future generations of multiprocessing systems. In this paper, we propose a new adaptive unicast routing algorithm and four software-based (unicast-based) broadcast algorithms for the wormhole switched OTI S-hypercube. We then present an empirical performance evaluation of these algorithms in OTIS-hypercube for different topologies, message length and traffic loads. © 2008 IEEE  

    Tomographical medical image reconstruction using Kalman filter technique

    , Article Proceedings - 9th IEEE International Symposium on Parallel and Distributed Processing with Applications Workshops, ISPAW 2011 - ICASE 2011, SGH 2011, GSDP 2011, 26 May 2011 through 28 May 2011 ; May , 2011 , Pages 61-65 ; 9780769544298 (ISBN) Goliaei, S ; Ghorshi, S ; Sharif University of Technology
    2011
    Abstract
    In this paper, a Kalman filter technique which is operated in time is introduced for noise reduction on CT set of projections to reconstruct medical images. The experiments were done on medical image of kidneys and the simulated projections are captured by CT scanner. Evaluation results indicated that as the number of projections increase in the collected ray sums corrupted by noise the quality of reconstructed image becomes better in terms of contrast and transparency. However, for the comparison issue, the same conditions are applied for reconstruction of medical image in frequency domain using filter back projection technique. It observes that filter back projection technique does not... 

    Robust control of an autonomous four-wire electronically-coupled distributed generation unit

    , Article IEEE Transactions on Power Delivery ; Volume 26, Issue 1 , September , 2011 , Pages 455-466 ; 08858977 (ISSN) Karimi, H ; Yazdani, A ; Iravani, R ; Sharif University of Technology
    2011
    Abstract
    This paper proposes a control strategy for the autonomous (islanded) operation of a four-wire, electronically-coupled distributed generation (DG) unit which can feed a highly unbalanced load, e.g., due to the presence of single-phase loads. In the grid-connected mode, the power-electronic interface of the DG unit enables the exchange of real and reactive power with the distribution network, based on the conventional dq-frame current control strategy. The current control scheme is disabled subsequent to the detection of an islanding event, and the proposed controller is activated. The proposed control strategy utilizes: i) an internal oscillator to maintain the island frequency and ii) a... 

    Distributed and decentralized state estimation in gas networks as distributed parameter systems

    , Article ISA Transactions ; Volume 58 , September , 2015 , Pages 552-566 ; 00190578 (ISSN) Ahmadian Behrooz, H ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    ISA - Instrumentation, Systems, and Automation Society  2015
    Abstract
    In this paper, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. The non-isothermal model of the plant including mass, momentum and energy balance equations are used to simulate the dynamic behavior. Due to several disadvantages of implementing a centralized Kalman filter for large-scale systems, the continuous/discrete form of extended Kalman filter for distributed and decentralized estimation (DDE) has been extended for these systems. Accordingly, the global model is decomposed into several subsystems, called local models. Some heuristic rules are suggested for system decomposition in gas pipeline... 

    Optimal gas distribution network using minimum spanning tree

    , Article Proceedings - 2010 IEEE 17th International Conference on Industrial Engineering and Engineering Management, IE and EM2010, 29 October 2010 through 31 October 2010 ; October , 2010 , Pages 1374-1377 ; 9781424464814 (ISBN) Mahdavi, I ; Mahdavi Amiri, N ; Makui, A ; Mohajeri, A ; Tafazzoli, R ; Sharif University of Technology
    2010
    Abstract
    Here, a case study of natural gas network is conducted. We design an optimal distribution network of natural gas. Our proposed network is composed of stations reducing gas pressure to desirable pressure using consumer's viewpoint. By using minimum spanning tree (MST) technique, an optimal distribution network among stations and consumers is constructed. Our aim is to determine both locations and types of stations minimizing location-allocation costs in the network. A case study in Mazandaran Gas Company in Iran is made to assess the validity and effectiveness of the proposed model  

    Introducing a new intelligent adaptive learning content generation method

    , Article 2010 2nd International Conference on E-Learning and E-Teaching, ICELET 2010, 1 December 2010 through 2 December 2010 ; December , 2010 , Pages 65-71 ; 9781424490110 (ISBN) Haghshenas, E ; Mazaheri, A ; Gholipour, A ; Tavakoli, M ; Zandi, N ; Narimani, H ; Rahimi, F ; Nouri, S ; Sharif University of Technology
    2010
    Abstract
    E-learning environments are being used more efficiently by the rapid growth in internet and multimedia technologies. Adaptive learning is a kind of learning environment which provides individual learning. It can customize the learning style according to the individual's personality and characteristics. Although there are a lot of e-learning systems having adaptive learning feature, they do not satisfy all adaptive learning aspects. This paper proposes a new method which tries to help learners find educational contents adapted to their personalities in an efficient manner. Our proposed method has four essential parts: 1) It finds out learner's features by Bayesian networks. 2) Then It tries... 

    Automatic design of conventional distillation column sequence by genetic algorithm

    , Article Canadian Journal of Chemical Engineering ; Volume 87, Issue 3 , 2009 , Pages 477-492 ; 00084034 (ISSN) Bozorgmehry Boozarjomehry, R ; Pourahmadi Laleh, A ; Svrcek, W. Y ; Sharif University of Technology
    2009
    Abstract
    Synthesis of the optimum conventional (with non-sharp separations) distillation column sequence (DCS) is a challenging problem, in the field of chemical process design and optimization, due to its huge search space and combinatorial nature. In this paper, a novel procedure for the synthesis of optimum Conventional Distillation Column Sequence is proposed. The proposed method is based on evolutionary algorithms. The main criterion used to screen alternative DCS's is the Total Annual Cost (TAC). In order to estimate the TAC of each DCS alternative all columns that exist in the DCS are designed using short-cut methods. The performance of the proposed method and other alternatives are compared... 

    Multi objective distributed generation planning using a binary particle swarm optimization method

    , Article 2008 International Conference on Genetic and Evolutionary Methods, GEM 2008, Las Vegas, NV, 14 July 2008 through 17 July 2008 ; 2008 , Pages 140-146 ; 1601320698 (ISBN); 9781601320698 (ISBN) Soroudi, A ; Ehsan, M ; Sharif University of Technology
    2008
    Abstract
    With the introduction of restructuring concepts to traditional power systems, a great deal of attention is given to utilization of distributed generation. Integration of DG units has been known as an alternative for distribution network reinforcement and purchasing energy from transmission network. Considering these facts, in the planning procedure of DG, determination of optimal sizing and sitting is a very important issue. This work presents a comprehensive framework for integration of distributed generations into a distribution network, regarding various technical and economical issues such as reduction of active power losses, environmental pollutions, investment and running costs while... 

    Reliability assessment of distribution system with distributed generation

    , Article 2008 IEEE 2nd International Power and Energy Conference, PECon 2008, Johor Baharu, 1 December 2008 through 3 December 2008 ; January , 2008 , Pages 1551-1556 ; 9781424424054 (ISBN) Jahangiri, P ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2008
    Abstract
    Reliability assessment is of primary importance in designing and planning distribution systems that operate in an economical manner with minimal interruption of customer loads. Distributed generation (DG) is expected to play an increasing role in emerging power systems because they use different type of resources and technologies to serve energy to power systems. DG is expected to improve the system reliability as its backup generation. Since DG units are subject to failures as all other generation units, the random behavior of these units must be taken into account in the analysis. Existence of DG units in a distribution system will effect on restoration time of load points. In this paper,... 

    Performance evaluation of broadcast algorithms in all-port 2D mesh networks

    , Article 2008 International Symposium on Parallel and Distributed Processing with Applications, ISPA 2008, Sydney, NSW, 10 December 2008 through 12 December 2008 ; December , 2008 , Pages 643-648 ; 9780769534718 (ISBN) Khorramabadi, M ; Sarbazi Azad, H ; Sharif University of Technology
    2008
    Abstract
    Broadcast is among the most primitive collective communication operations of any interconnection network. Broadcast algorithms for the mesh topology have been widely reported in the literature. However, most existing algorithms have been studied in one-port and within limited conditions, such as light traffic loads. In contrast, this study simulates the broadcast operations, taking into account a wide range of traffic loads. Also, the performance evaluation of meshes in the presence of unicast and broadcast traffic is presented in this paper. To the best of our knowledge, this study is the first to consider the issue of broadcast latency at both the network and node levels. A new model for... 

    Using genetic alghoritm for distributed generation allocation to reduce losses and improve voltage profile

    , Article 42nd International Universities Power Engineering Conference, UPEC 2007, Brighton, 4 September 2007 through 6 September 2007 ; 2007 , Pages 954-959 ; 1905593368 (ISBN); 9781905593361 (ISBN) Alinejad Beromi, Y ; Sedighizadeh, M ; Bayat, M. R ; Khodayar, M. E ; Sharif University of Technology
    2007
    Abstract
    This paper presents a method for the optimal allocation of Distributed generation in distribution systems. In this paper, our aim would be optimal distributed generation allocation for voltage profile improvement and loss reduction in distribution network. Genetic Algorithm (GA) was used as the solving tool, which referring two determined aim; the problem is defined and objective function is introduced. Considering to fitness values sensitivity in genetic algorithm process, there is needed to apply load flow for decision-making. Load flow algorithm is combined appropriately with GA, till access to acceptable results of this operation. We used MATPOWER package for load flow algorithm and... 

    Reliability worth assessment of an automatic loop restoration scheme for urban distribution networks

    , Article IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe ; 2010 Kazemi, S ; Lehtonen, M ; Fotuhi-Firuzabad, M ; Sharif University of Technology
    Abstract
    Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability... 

    A possibilistic-probabilistic tool for evaluating the impact of stochastic renewable and controllable power generation on energy losses in distribution networks-A case study

    , Article Renewable and Sustainable Energy Reviews ; Volume 15, Issue 1 , 2011 , Pages 794-800 ; 13640321 (ISSN) Soroudi, A ; Ehsan, M ; Sharif University of Technology
    Abstract
    This paper proposes a hybrid possibilistic-probabilistic evaluation tool for analyzing the effect of uncertain power production of distributed generations (DGs) on active losses of distribution networks. The considered DG technologies are gas and wind turbines. This tool is useful for distribution network operators (DNOs) when they are faced with uncertainties which some of them can be modeled probabilistically and some of them are described possibilistically. The generation pattern of DG units changes the flow of lines and this will cause change of active losses which DNO is responsible for compensating it. This pattern is highly dependent on DG technology and also on decisions of DG... 

    Modeling and state estimation for gas transmission networks

    , Article Journal of Natural Gas Science and Engineering ; Volume 22 , 2015 , Pages 551-570 ; 18755100 (ISSN) Ahmadian Behrooz, H ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In this paper, a non-isothermal model of natural gas in pipelines including mass, momentum and energy balance equations are used as model equations for modeling and state estimation in gas pipeline systems. It is shown that differential equations describing the dynamic behavior of a high-pressure and long-distance gas transmission network (GTN) can be solved efficiently using the orthogonal collocation method. The issues corresponding to the presence of discontinuities in the dynamic model is substantially discussed and studied. The non-isothermal model of a GTN can experience discontinuities during transient operations, which causes challenges in simulation and state estimation in this... 

    Reliability worth assessment of an automatic loop restoration scheme for urban distribution networks

    , Article IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe, 11 October 2010 through 13 October 2010 ; October , 2010 ; 9781424485109 (ISBN) Kazemi, S ; Lehtonen, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2010
    Abstract
    Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability... 

    An asynchronous dynamic Bayesian network for activity recognition in an ambient intelligent environment

    , Article ICPCA10 - 5th International Conference on Pervasive Computing and Applications, 1 December 2010 through 3 December 2010 ; December , 2010 , Pages 20-25 ; 9781424491421 (ISBN) Mirarmandehi, N ; Rabiee, H. R ; Sharif University of Technology
    2010
    Abstract
    Ambient Intelligence is the future of computing where devices predict what users need and help them carry out their everyday life activities easier. To make this prediction possible these environments should be aware of the context. Activity recognition is one of the most complex problems in context-aware environments. In this paper we propose a layered Dynamic Bayesian Network (DBN) to recognize activities in an oral presentation. The layered architecture gives us the opportunity to recognize complex activities using the classification results of sensory data in the first layer regardless of the physical environment. Our model is event-driven meaning the classification takes place only when...