Search for: cost-reduction
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    Project Scheduling Subject to Non-Renewable Perishable Resources

    , M.Sc. Thesis Sharif University of Technology Najafi Farashah, Mohammad Hadi (Author) ; Shadrokh, Shahram (Supervisor)
    In this research a mathematical formulation is presented for project scheduling problem subject to non-renewable perishable resources where the objective is minimize the cost of ordering and maintenance of resources. We use the framework of a resource constrained project scheduling problem (RCPSP) with finish-start precedence relations between activities and resources will be perished after a determined duration and must be procured. Resource procurement have ordering and purchasing costs and excess resources must be stored and have maintenance cost. There is a unique way to perform the activities and preemption is not allowed.
    This work employs Genetics Algorithms to solve the problem... 

    Weak visibility counting in simple polygons

    , Article Journal of Computational and Applied Mathematics ; Volume 288 , November , 2015 , Pages 215-222 ; 03770427 (ISSN) Nouri Bygi, M ; Daneshpajouh, S ; Alipour, S ; Ghodsi, M ; Sharif University of Technology
    Elsevier  2015
    For a simple polygon P of size n, we define weak visibility counting problem (WVCP) as finding the number of visible segments of P from a query line segment pq. We present different algorithms to compute WVCP in sub-linear time. In our first algorithm, we spend O(n7) time to preprocess the polygon and build a data structure of size O(n6), so that we can optimally answer WVCP in O(logn) time. Then, we reduce the preprocessing costs to O(n4+ε) time and space at the expense of more query time of O(log5n). We also obtain a trade-off between preprocessing and query time costs. Finally, we propose an approximation method to reduce the preprocessing costs to O(n2) time and space and O(n1/2+ε) query... 

    Toward an architecture-based method for selecting composer components to make software product line

    , Article ITNG2010 - 7th International Conference on Information Technology: New Generations, 12 April 2010 through 14 April 2010 ; April , 2010 , Pages 1233-1236 ; 9780769539843 (ISBN) Tanhaei, M ; Moaven, S ; Habibi, J ; Sharif University of Technology
    Nowadays, product line, as an important topic in software development domain, has been paid attention by software engineering practitioners. Finding suitable components to construct an efficient and comprehensive product line with low costs is one of the critical problems in this domain which demands to be satisfied. In this paper a method is presented which can manage and control complexities of component selection problem, an NP problem, and result in creation of declared product line. By making use of this method, a product line will be constructed with suitably-adopted components to cover up requirements based on architecture; that's why software product line development process will... 

    Toward a collaborative method for knowledge management of software architectural decisions based on trust

    , Article 12th International Conference on Fuzzy Systems and Knowledge Discovery, 15 August 2015 through 17 August 2015 ; 2015 , Pages 828-834 ; 9781467376822 (ISBN) Samghani Nejad, M ; Moaven, S ; Habibi, J ; Alidousti, R
    Institute of Electrical and Electronics Engineers Inc 
    Design and implementation of Architecture is a knowledge-driven process. Evaluation and verification the knowledge, in order to ensure its quality, have important role in improving overall design process. Furthermore, Architectural decision making is a complex and multi-criteria decision making problem in which multiple stakeholders make decisions from their perspectives causing overlaps and conflicts in the adopted decisions. Therefore, the requirement for strategies to manage these issues and also to improve coordination and cooperation among the various stakeholders to improve the overall process design is necessary. In this regard, there have been several activities that focus on... 

    Toward a business model for software product line architecture

    , Article 8th ACIS International Conference on Software Engineering Research, Management and Applications, SERA 2010, 24 May 2010 through 26 May 2010, Montreal, QC ; 2010 , Pages 50-56 ; 9780769540757 (ISBN) Tanhaei, M ; Moaven, S ; Habibi, J ; Ahmadi, H ; Sharif University of Technology
    Nowadays, software product line is an approach to reduce costs of software development, decrease time to market, and increase capabilities of reuse in designing and exploiting software development processes. Moreover, other quality attributes of the project domain should be considered to enhance quality of the product. Meanwhile, taking advantage of software product line makes developers capable of estimating development costs and time to market in a more realistic way. However, old approaches to estimate cost of development and foresee time to market are not suitable enough for software product line. In this paper, some important business parameters and a way to calculate cost and time to... 

    The impact of demand response programs on UPFC placement

    , Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 27, Issue 6 , 2019 , Pages 4624-4639 ; 13000632 (ISSN) Sharifi Nasab Anari, A ; Ehsan, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Turkiye Klinikleri  2019
    Demand response (DR) and flexible AC transmission system (FACTS) devices can be effectively used for congestion management in power transmission systems. However, demand response program (DRP) implementation can itself affect the optimum location of FACTS devices, which is one of the main issues in power system planning. This paper investigates the impact of DRPs on unified power flow controller (UPFC) placement. The harmony search algorithm is employed to determine the optimum locations and parameter setting of UPFC in a long-term framework. The optimization problem is solved with different objectives including generation and congestion cost reduction, as well as loss reduction. In this... 

    Technical assessment of ground-source, air-source, and hybrid heat pumps for single-family buildings in cold climates

    , Article 25 June 2016 through 29 June 2016 ; Volume 122 , 2016 , Pages 270-280 ; 00012505 (ISSN) ; 9781939200464 (ISBN) Eslami Nejad, P ; Hakkaki Fard, A. M ; Aidoun, Z ; Ouzzane, M ; Sharif University of Technology
    Amer. Soc. Heating, Ref. Air-Conditoning Eng. Inc 
    This paper discusses a technical comparison of a directexpansion ground-source heat pump (DX-GSHP) and an airsource heat pump (ASHP). To lower the ground heat exchanger size for cost reduction purposes, the system performance of a hybrid system is also evaluated using a supplementary air evaporator combined with the DX-GSHP. Detailed screening models previously developed for ASHPs and DX-GHSPs are first used to compare the seasonal performance of these two options for a residential building in the cold-climate city of Montreal, Canada. Then, the model is adopted for performance evaluation of the hybrid system. Additionally, different parameters including borehole total length and heat pump... 

    STAIR: high reliable STT-MRAM aware multi-level I/O cache architecture by adaptive ECC allocation

    , Article 2020 Design, Automation and Test in Europe Conference and Exhibition, DATE 2020, 9 March 2020 through 13 March 2020 ; 2020 , Pages 1484-1489 Hadizadeh, M ; Cheshmikhani, E ; Asadi, H ; ACM Special Interest Group on Design Automation (SIGDA); et al.; European Design and Automation Association (EDAA); European Electronic Chips and Systems Design Initiative (ECSI); IEEE Council on Electronic Design Automation (CEDA); SEMI Strategic Technology Community and Electronic System Design Alliance (ESD Alliance) ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Hybrid Multi-Level Cache Architectures (HCAs) are promising solutions for the growing need of high-performance and cost-efficient data storage systems. HCAs employ a high endurable memory as the first-level cache and a Solid-State Drive (SSD) as the second-level cache. Spin-Transfer Torque Magnetic RAM (STT-MRAM) is one of the most promising candidates for the first-level cache of HCAs because of its high endurance and DRAM-comparable performance along with non-volatility. However, STT-MRAM faces with three major reliability challenges named Read Disturbance, Write Failure, and Retention Failure. To provide a reliable HCA, the reliability challenges of STT-MRAM should be carefully addressed.... 

    SMART: a scalable mapping and routing technique for power-gating in NoC routers

    , Article 2017 11th IEEE/ACM International Symposium on Networks-on-Chip, NOCS 2017, 19 October 2017 through 20 October 2017 ; 2017 ; 9781450349840 (ISBN) Farrokhbakht, H ; Kamali, H. M ; Hessabi, S
    Reducing the size of the technology increases leakage power in Network-on-Chip (NoC) routers drastically. Power-gating, particularly in NoC routers, is one of the most efficient approaches for alleviating the leakage power. Although applying power-gating techniques alleviates NoC power consumption due to high proportion of idleness in NoC routers, since the timing behavior of packets is irregular, even in low injection rates, performance overhead in power-gated routers is significant. In this paper, we present SMART, a Scalable Mapping And Routing Technique, with virtually no area overhead on the network. It improves the irregularity of the timing behavior of packets in order to mitigate... 

    Reducing motion estimation time with skin detection

    , Article 2009 IEEE International Workshop on Imaging Systems and Techniques, IST 2009, Hong Kong, 11 May 2009 through 12 May 2009 ; 2009 , Pages 71-75 ; 9781424434831 (ISBN) Shirali Shahreza, M. H ; Shirali Shahreza, S ; IEEE Instrumentation and Measurement Society ; Sharif University of Technology
    Motion estimation (ME) is one of the key parts of video compression algorithms. But, motion estimation and computation of motion vectors (MVs) are very time con-suming. In this paper, we propose a method for reducing the cost of motion estimation process. During this process, a series of candidate blocks should be searched to find the best motion vectors. In our method, we compare the skin parts of two blocks before comparing all pixel pairs of the two blocks. Having a preprocessing phase, the skin part comparison is performed quickly. This method provides a parameter that can be used to create a balance between the processing time and the motion estimation accuracy. © 2009 IEEE  

    Recent progress in inorganic and composite coatings with bactericidal capability for orthopaedic applications

    , Article Nanomedicine: Nanotechnology, Biology, and Medicine ; Volume 7, Issue 1 , Feb , 2011 , Pages 22-39 ; 15499634 (ISSN) Simchi, A ; Tamjid, E ; Pishbin, F ; Boccaccini, A. R ; Sharif University of Technology
    This review covers the most recent developments of inorganic and organic-inorganic composite coatings for orthopedic implants, providing the interface with living tissue and with potential for drug delivery to combat infections. Conventional systemic delivery of drugs is an inefficient procedure that may cause toxicity and may require a patient's hospitalization for monitoring. Local delivery of antibiotics and other bioactive molecules maximizes their effect where they are required, reduces potential systemic toxicity and increases timeliness and cost efficiency. In addition, local delivery has broad applications in combating infection-related diseases. Polymeric coatings may present some... 

    Profit-based unit commitment of integrated CHP-thermal-heat only units in energy and spinning reserve markets with considerations for environmental CO2 emission cost and valve-point effects

    , Article Energy ; Volume 133 , 2017 , Pages 621-635 ; 03605442 (ISSN) Nazari, M. E ; Ardehali, M. M ; Sharif University of Technology
    Elsevier Ltd  2017
    For the purposes of lowering environmental emission cost and increasing economic profit, energy efficient combined heat and power (CHP) units can be integrated with conventional separate heat and power production units to meet heat and power demands. The goal of this study is to develop and examine a novel heuristic and deterministic optimization algorithm for solving the profit-based unit commitment (PBUC) problem for a generation company with integrated CHP-thermal-heat only system for (i) satisfying demands for heat and power, (ii) selling spinning reserve for power, (iii) reducing environmental CO2 emission cost, and (iv) accounting for valve-point effects for steam turbines. For... 

    Optimization of the municipal solid waste management system using a hybrid life cycle assessment–emergy approach in Tehran

    , Article Journal of Material Cycles and Waste Management ; Volume 22, Issue 1 , 2020 , Pages 133-149 Falahi, M ; Avami, A ; Sharif University of Technology
    Springer  2020
    The sustainable design of the waste-management system is of crucial importance for cities like Tehran, capital of Iran. Tehran’s municipal solid-waste management has adopted modern practices and technologies very slowly. This study proposes the optimum pathway to reach maximum environmental benefits as well as the most cost-effective technologies according to the financial limits. The hybrid life cycle assessment (LCA)–emergy approach is applied to utilize the life cycle emissions as an inventory database to estimate the ecosystem services provided by the natural ecosystem to dilute the emissions and compensate raw material consumption. Among organic waste-treatment options, composting is... 

    Optimal switch placement in power distribution systems with complex configurations

    , Article 2019 Smart Gird Conference, SGC 2019, 18 December 2019 through 19 December 2019 ; 2019 ; 9781728158945 (ISBN) Jalilian, A ; Taheri, B ; Safdarian, A ; Sharif University of Technology
    Institute of electrical and electronics engineers Inc  2019
    Sectionalizing switches are the main components of any restoration scheme in fault situations of power distribution systems. In this paper, customer outage costs reduction is aimed through the optimal simultaneous placement of manual and remote-controlled switches (RCSs). Network reconfigurations are constrained such that operational considerations like statutory ranges for voltage levels, lines' thermal capacities, and necessity of radial configuration be conserved. Total cost reduction is mathematically modeled in a mixed-integer linear programming (MILP) model that makes the global optimal solution accessible. The validity of the proposed model is evaluated on the IEEE 33-bus network. In... 

    Optimal scheduling of multi-carrier energy system based on energy hub concept considering power-to-gas storage

    , Article IEEE Power and Energy Society Innovative Smart Grid Technologies Conference, ISGT 2020, 17 through 20 February 2020 ; 7 May , 2020 Habibifar, R ; Khoshjahan, M ; Ghasemi, M. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Supplying sustainable energy is of a critical prominence nowadays. A main outcome of the galloping development in energy generation technologies is the ability to integrate multi-carrier energy systems that facilitates meeting the fast growth of energy demand. Energy hub is one of the main infrastructures making the incorporation of multi-carrier systems smoother. In this paper, the optimal scheduling problem of an energy hub structure equipped with combined heat and power, boiler, power-to-gas storage, thermal energy storage and electrical energy storage in order to supply power, heat and gas demands is presented. Power to gas is regarded as a new technology that creates a connection... 

    Optimal energy management of a campus microgrid considering financial and economic analysis with demand response strategies

    , Article Energies ; Volume 14, Issue 24 , 2021 ; 19961073 (ISSN) Javed, H ; Muqeet, H. A ; Shehzad, M ; Jamil, M ; Khan, A. A ; Guerrero, J. M ; Sharif University of Technology
    MDPI  2021
    An energy management system (EMS) was proposed for a campus microgrid (μG) with the incorporation of renewable energy resources to reduce the operational expenses and costs. Many uncertainties have created problems for microgrids that limit the generation of photovoltaics, causing an upsurge in the energy market prices, where regulating the voltage or frequency is a challenging task among several microgrid systems, and in the present era, it is an extremely important research area. This type of difficulty may be mitigated in the distribution system by utilizing the optimal demand response (DR) planning strategy and a distributed generator (DG). The goal of this article was to present a... 

    Optimal distribution network automation considering earth fault events

    , Article IEEE Transactions on Smart Grid ; Vol. 6, issue. 2 , 2015 , p. 1010-1018 ; ISSN: 19493053 Siirto, O. K ; Safdarian, A ; Lehtonen, M ; Fotuhi-Firuzabad, M ; Sharif University of Technology
    In the past decade, distribution network operators have been broadly engrossed toward automated distribution networks. The operators acknowledge network automation as an efficient investment toward a better service reliability. This paper aims to provide a new long-term cost/benefit analysis for an optimal level of distribution network automation. In the analysis, reduction in customer outage cost is considered as the benefit of implementing automation systems with capital investment, and annual operation and maintenance costs. In the Finnish regulation model, there is a special incentive based on customer outage cost reduction. As the main contribution of this paper, the impact of earth... 

    Optimal distribution network automation considering earth fault events

    , Article IEEE Transactions on Smart Grid ; Volume 6, Issue 2 , 2015 , Pages 1010-1018 ; 19493053 (ISSN) Siirto, O. K ; Safdarian, A ; Lehtonen, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
    In the past decade, distribution network operators have been broadly engrossed toward automated distribution networks. The operators acknowledge network automation as an efficient investment toward a better service reliability. This paper aims to provide a new long-term cost/benefit analysis for an optimal level of distribution network automation. In the analysis, reduction in customer outage cost is considered as the benefit of implementing automation systems with capital investment, and annual operation and maintenance costs. In the Finnish regulation model, there is a special incentive based on customer outage cost reduction. As the main contribution of this paper, the impact of earth... 

    One-for-one period policy and a series of suppliers

    , Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009, 6 July 2009 through 9 July 2009, Troyes ; 2009 , Pages 902-906 ; 9781424441365 (ISBN) Haji, R ; Pirayesh Neghab, M ; Haji, A ; Sharif University of Technology
    The purpose of this paper is to adopt and analyze a new ordering policycalled one-for-one-period policy in a multi-echelon supply chain consisting ofone retailer and a series of TV suppliers. The main advantage of adopting theone-for-one-period (7,7) ordering policy for retailers is the elimination ofuncertainty for supplier which leads to total elimination of the safety stocksat all suppliers. This in turn leads to the reduction of the total system costsand in case any supplier's ordering cost is negligible it can even eliminate theneed for him to carry any inventory. In addition to this advantage, thenumerical results show that the application of this new policy for the retailerleads to... 

    One cube or more?

    , Article 59th International Astronautical Congress 2008, IAC 2008, Glasgow, 29 September 2008 through 3 October 2008 ; Volume 6 , 2008 , Pages 3792-3797 ; 9781615671601 (ISBN) Bakhtiari Mojaz, S ; Shahmari, E ; Molaverdikhani, K ; Jazebizadeh, H ; Taheran, M ; Sharif University of Technology
    In the recent years, many universities invest on cubesats to prepare an appropriate environment for their students to get their hands on real experiments including design, fabrication, test, launch, operation and analysis of a real satellite project. Now after 5 years of experimentation, it is time for leaders to define more practical goals beside training students. Orienting the budget that is annually being invested on such satellites in every country to a specific goal could be a driving force in opening a new chapter in the utilization of pico-satellites and the advantages they offer. As these tiny satellites are utilized based on low cost COTS and also are light weight enough to reduce...