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Implementation-aware model analysis: The case of buffer-throughput tradeoff in streaming applications
, Article Proceedings of the ACM SIGPLAN Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES), 18 June 2015 through 19 June 2015 ; Volume 2015-June , 2015 , Pages 108-117 ; 9781450332576 (ISBN) ; Hashemi, M ; Khibin, V ; Ghiasi, S ; Sharif University of Technology
Association for Computing Machinery
2015
Abstract
Models of computation abstract away a number of implementation details in favor of well-defined semantics. While this has unquestionable benefits, we argue that analysis of models solely based on operational semantics (implementation oblivious analysis) is unfit to drive implementation design space exploration. Specifically, we study the tradeoff between buffer size and streaming throughput in applications modeled as synchronous data flow (SDF) graphs. We demonstrate the inherent inaccuracy of implementation-oblivious approach, which only considers SDF operational semantic. We propose a rigorous transformation, which equips the state of the art buffer-throughput tradeoff analysis technique...
Implementation-aware model analysis: The case of buffer-throughput tradeoff in streaming applications
, Article ACM SIGPLAN Notices ; Volume 50, Issue 5 , May , 2015 , Pages 103-112 ; 15232867 (ISSN) ; Hashemi, M ; Khibin, V ; Ghiasi, S ; Sharif University of Technology
Association for Computing Machinery
2015
Abstract
Models of computation abstract away a number of implementation details in favor of well-defined semantics. While this has unquestionable benefits, we argue that analysis of models solely based on operational semantics (implementationoblivious analysis) is unfit to drive implementation design space exploration. Specifically, we study the tradeoff between buffer size and streaming throughput in applications modeled as synchronous data flow (SDF) graphs. We demonstrate the inherent inaccuracy of implementationoblivious approach, which only considers SDF operational semantic. We propose a rigorous transformation, which equips the state of the art buffer-throughput tradeoff analysis technique...
A cloud computing framework on demand side management game in smart energy hubs
, Article International Journal of Electrical Power and Energy Systems ; Volume 64 , January , 2015 , Pages 1007-1016 ; 01420615 (ISSN) ; Rayati, M ; Bahrami, S ; Ranjbar, A. M ; Sattari, S ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The presence of energy hubs in the future vision of energy networks creates an opportunity for electrical engineers to move toward more efficient energy systems. At the same time, it is envisioned that smart grid can cover the natural gas network in the near future. This paper modifies the classic Energy Hub model to present an upgraded model in the smart environment entitling "Smart Energy Hub". Supporting real time, two-way communication between utility companies and smart energy hubs, and allowing intelligent infrastructures at both ends to manage power consumption necessitates large-scale real-time computing capabilities to handle the communication and the storage of huge transferable...
On endurance and performance of erasure codes in SSD-based storage systems
, Article Microelectronics Reliability ; Volume 55, Issue 11 , 2015 , Pages 2453-2467 ; 00262714 (ISSN) ; Delavari, Z ; Miremadi, S. G ; Asadi, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Erasure codes are widely used in data storage systems to protect against disk failures. Employing erasure codes in an array of Solid-State Drives (SSDs) in storage systems necessitates designers to revisit different characteristics in comparison to Hard Disk Drives (HDDs), due to non-mechanical property of SSDs. One of the most important characteristics of SSDs is their limitation on the number of Program/Erase (P/E) cycles. By taking into account the characteristics of SSDs, this paper presents a comprehensive analysis to investigate the effects of three well-known erasure codes on the endurance and performance of SSD-based disk subsystems. The three erasure codes, i.e., Reed-Solomon,...
Evaluation of methods for estimating aquifer hydraulic parameters
, Article Applied Soft Computing Journal ; Volume 28 , March , 2015 , Pages 541-549 ; 15684946 (ISSN) ; Mortazavi Naeini, M ; Ataie Ashtiani, B ; Jeng, D. S ; Khanbilvardi, R ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
An accurate estimation of aquifer hydraulic parameters is required for groundwater modeling and proper management of vital groundwater resources. In situ measurements of aquifer hydraulic parameters are expensive and difficult. Traditionally, these parameters have been estimated by graphical methods that are approximate and time-consuming. As a result, nonlinear programming (NLP) techniques have been used extensively to estimate them. Despite the outperformance of NLP approaches over graphical methods, they tend to converge to local minima and typically suffer from a convergence problem. In this study, Genetic Algorithm (GA) and Ant Colony Optimization (ACO) methods are used to identify...
Probabilistic key pre-distribution for heterogeneous mobile ad hoc networks using subjective logic
, Article Proceedings - International Conference on Advanced Information Networking and Applications, AINA, 25 March 2015 through 27 March 2015 ; Volume 2015-April , March , 2015 , Pages 185-192 ; 1550445X (ISSN) ; 9781479979042 (ISBN) ; Gharib, M ; Ghassemi, F ; Movaghar, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Public key management scheme in mobile ad hoc networks (MANETs) is an inevitable solution to achieve different security services such as integrity, confidentiality, authentication and non reputation. Probabilistic asymmetric key pre-distribution (PAKP) is a self-organized and fully distributed approach. It resolves most of MANET's challenging concerns such as storage constraint, limited physical security and dynamic topology. In such a model, secure path between two nodes is composed of one or more random successive direct secure links where intermediate nodes can read, drop or modify packets. This way, intelligent selection of intermediate nodes on a secure path is vital to ensure security...
Single Event Multiple Upset (SEMU) tolerant latch designs in presence of process and temperature variations
, Article Journal of Circuits, Systems and Computers ; Volume 24, Issue 1 , January , 2015 ; 02181266 (ISSN) ; Tabandeh, M ; Fazeli, M ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2015
Abstract
In this paper, we propose two novel soft error tolerant latch circuits namely HRPU and HRUT. The proposed latches are both capable of fully tolerating single event upsets (SEUs). Also, they have the ability of enduring single event multiple upsets (SEMUs). Our simulation results show that, both of our HRPU and HRUT latches have higher robustness against SEMUs as compared with other recently proposed radiation hardened latches. We have also explored the effects of process and temperature variations on different design parameters such as delay and power consumption of our proposed latches and other leading SEU tolerant latches. Our simulation results also show that, compared with the reference...
Part load behavior of molten salt cavity receiver solar tower plants under storage mode operational mode
, Article ASME 2016 10th International Conference on Energy Sustainability, ES 2016, collocated with the ASME 2016 Power Conference and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology, 26 June 2016 through 30 June 2016 ; Volume 1 , 2016 ; 9780791850220 (ISBN) ; Shafiei Ghazani, A ; Taylor, R. A ; Saberi, P ; Sharif University of Technology
American Society of Mechanical Engineers
2016
Abstract
The performance of the tower based concentrated solar thermal (CST-tower) plant is very sensitive to the operation strategy of the plant and the incident heat flux on the receiver. To date, most studies have been examined only the design mode characteristics of the cavity receivers, but this paper significantly expands the literature by considering non-design operating conditions of this important sub-component of the CST-tower plants. A feasible non-design operating conditions of the cavity receivers that was considered in this study is the storage mode of operation. Two practical dynamic control strategies were examined then to find the most efficient approach: fixed solar field mass...
Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures
, Article Road Materials and Pavement Design ; 2016 , Pages 1-22 ; 14680629 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This...
A hybrid Non-Volatile Cache Design for Solid-State Drives using comprehensive I/O characterization
, Article IEEE Transactions on Computers ; Volume 65, Issue 6 , 2016 , Pages 1678-1691 ; 00189340 (ISSN) ; Asadi, H ; Haghdoost, A ; Arjomand, M ; Sarbazi Azad, H ; Sharif University of Technology
IEEE Computer Society
Abstract
The emergence of new memory technologies provides us with opportunity to enhance the properties of existing memory architectures. One such technology is Phase Change Memory (PCM) which boasts superior scalability, power savings, non-volatility, and a performance competitive to Dynamic Random Access Memory (DRAM). In this paper, we propose a write buffer architecture for Solid-State Drives (SSDs) which attempts to exploit PCM as a DRAM alternative while alleviating its issues such as long write latency, high write energy, and finite endurance. To this end and based on thorough I/O characterization of desktop and enterprise applications, we propose a hybrid DRAM-PCM SSD cache design with an...
New correlations for predicting pure and impure natural gas viscosity
, Article Journal of Natural Gas Science and Engineering ; Volume 30 , 2016 , Pages 364-378 ; 18755100 (ISSN) ; Shams, R ; Ghazanfari, M. H ; Sharif University of Technology
Elsevier
2016
Abstract
Accurate determination of natural gas viscosity is important for successful design of production, transportation, and gas storage systems. However, most of available models/correlations suffer from complexity, robustness, and inadequate accuracy especially when wide range of pressure and temperature is applied. Present study illustrates development of two novel models for predicting natural gas viscosity for pure natural gas (CH4) as well as natural gas containing impurities. For this purpose, 6484 data points have been gathered and analyzed from the open literature covering wide range of pressure, temperature, and specific gravity levels, temperature ranges from -262.39 to 620.33 °F (109.6...
Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures
, Article Road Materials and Pavement Design ; Volume 18, Issue 6 , 2017 , Pages 1353-1374 ; 14680629 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Abstract
Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This...
Data block partitioning for recovering stuck-at faults in PCMs
, Article 2017 IEEE International Conference on Networking, Architecture, and Storage, NAS 2017 - Proceedings, 7 August 2017 through 9 August 2017 ; 2017 ; 9781538634868 (ISBN) ; Jalili, M ; Sarbazi Azad, H ; Sharif University of Technology
Abstract
Main burdens to the DRAM scalability are leakage and charge storage restrictions. Phase Change Memory (PCM) is being known as a promising candidate for the replacement of DRAM among competitive non-volatile memories. However, this memory suffers from low cell reliability due to limited write endurance. This problem can lead to some memory cells permanently stuck at either '0' or '1'. Therefore, a robust error recovery scheme is needed to overcome this problem and recover from hard errors. State-of-the-art solutions apply error correction and recovery techniques at inter-line or intra-line level. Precisely, they can improve PCM endurance either by remapping failed lines to spares (in...
OPTIMAS: overwrite purging through in-execution memory address snooping to improve lifetime of NVM-based scratchpad memories
, Article IEEE Transactions on Device and Materials Reliability ; Volume 17, Issue 3 , 2017 , Pages 481-489 ; 15304388 (ISSN) ; Farbeh, H ; Miremadi, S. G ; Sharif University of Technology
Abstract
SRAM-based scratchpad memories (SPMs) used in embedded systems impose high leakage power. Designing SPMs based on non-volatile memories (NVMs) were proposed as NVMs have negligible leakage power. The main problem of utilizing NVMs across the SPM is their limited number of write cycles (endurance). This problem threatens the reliability of NVM-based SPMs. To alleviate the problem of limited endurance in NVM-based SPMs, this paper proposes a method, called overwrite purging through in-execution memory address snooping (OPTIMAS). The main idea behind the proposed method is to control the lifetime of NVM-based SPMs, directly by a hardware unit, outside of the SPM mapping algorithm. This idea...
Developing a model for optimal sizing of a small hydropower/PV hybrid system for electrification
, Article 2017 5th IEEE International Conference on Smart Energy Grid Engineering, SEGE 2017, 14 August 2017 through 17 August 2017 ; 2017 , Pages 170-176 ; 9781538617755 (ISBN) ; Farshidian, B ; Saboohi, Y ; Sharif University of Technology
Abstract
The present study investigates the possibility of using a small hydropower/PV hybrid power system for low-cost electricity production which can satisfy the energy load requirements of a typical rural-urban area. In this context, the optimal dimensions to improve the technical and economical performances of the hybrid system are determined according to the load energy requirements and the solar and hydro resources data using linear programming. The application of the model is demonstrated using a case study of a rural-urban area in Mazandaran province, Iran. Two scenarios were considered for optimizing the system components. In the first scenario, a stand-alone hybrid small hydropower/PV...
Effect of nitrogen doping on glass transition and electrical conductivity of [EMIM][PF6] ionic liquid encapsulated in a zigzag carbon nanotube
, Article Journal of Physical Chemistry C ; Volume 121, Issue 29 , 2017 , Pages 15493-15508 ; 19327447 (ISSN) ; Minofar, B ; Sharif University of Technology
Abstract
Molecular level understanding of the properties of ionic liquids inside nanopores is needed in order to use ionic liquids for many applications such as electrolytes for energy storage in electric double-layer capacitors and dye-sensitized solar cells for conversion of solar energy. In this study, classical molecular dynamics (MD) simulations have been performed to investigate the radial distribution, glass transition, ionic transfer number, and electrical conductivity of the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate [EMIM][PF6] ionic liquid encapsulated in carbon nanotube (CNT). The effect of nitrogen as a doping element in CNT on these properties of [EMIM][PF6] was also...
A novel laparoscopic grasper with two parallel jaws capable of extracting the mechanical behaviour of soft tissues
, Article Journal of Medical Engineering and Technology ; Volume 41, Issue 5 , 2017 , Pages 339-345 ; 03091902 (ISSN) ; Farahmand, F ; Mirbagheri, A ; Afshari, E ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
Data related to force-deformation behaviour of soft tissue plays an important role in medical/surgical applications such as realistically modelling mechanical behaviour of soft tissue as well as minimally invasive surgery (MIS) and medical diagnosis. While the mechanical behaviour of soft tissue is very complex due to its different constitutive components, some issues increase its complexity like behavioural changes between the live and dead tissues. Indeed, an adequate quantitative description of mechanical behaviour of soft tissues requires high quality in vivo experimental data to be obtained and analysed. This paper describes a novel laparoscopic grasper with two parallel jaws capable of...
Optimization of the marinelli beaker dimensions using genetic algorithm
, Article Journal of Environmental Radioactivity ; Volume 172 , 2017 , Pages 81-88 ; 0265931X (ISSN) ; Hosseini, S. A ; Samadfam, M ; Sharif University of Technology
Abstract
A computational code, based on the genetic algorithm and MCNPX version 2.6 code was developed and used to investigate the effects of some important parameters of HPGe detector (such as Al cap thickness, dead-layer thickness and Ge hole size) on optimum dimensions of marinelli beaker. In addition, the effects of detector material on optimal beaker dimensions were also investigated. Finally, the optimized beaker dimensions at various beaker volumes (300, 500, 700, 1000 and 1500 cm3) were determined for some conventional Ge detectors with different crystal sizes (16 sizes). These sets of data then were used to drive mathematical formulas (obtained by best fitting to data sets). The results...
Achieving transparency in series elastic actuator of sharif lower limb exoskeleton using LLNF-NARX model
, Article 4th RSI International Conference on Robotics and Mechatronics, ICRoM 2016, 26 October 2016 through 28 October 2016 ; 2017 , Pages 398-403 ; 9781509032228 (ISBN) ; Ghaffari, S ; Vossoughi, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Nowadays, exoskeletons have been gaining popularity due to their potential use in rehabilitation and augmentation. These robots often utilize series elastic actuators to facilitate compliant interaction with the human. Numerous studies have been carried out with the purpose of identification and control of these type of actuators. The goal of this paper is to provide a method for dynamic modeling and identification of series elastic actuators. This model is then used in the control loop as a feed-forward term to eliminate the actuator's dynamics. Each series elastic actuator used in the Sharif wearable robot, uses a brushless DC motor, a torsional spring, a harmonic drive, a timing belt, a...
Implicit effect of decoding time on fault tolerance in erasure coded cloud storage systems
, Article 20th International Computer Science and Engineering Conference: Smart Ubiquitos Computing and Knowledge, ICSEC 2016, 14 December 2016 through 17 December 2016 ; 2017 ; 9781509044207 (ISBN) ; Miremadi, S. G ; Alinezhad Chamazcoti, S ; Sharif University of Technology
Abstract
International Data Company (IDC) has estimated the total amount of digital data stored in the world will reach 40 thousand Exabytes at the end of 2020. The idea of accessing this volume of data, anywhere at any time by exploiting commodity hardware, led to the introduction of cloud storage. The abounded rate and variety of failures in the equipment used in cloud storage systems, placed fault tolerance, at top of the challenges in these systems. Hadoop Distributed File System (HDFS) has provided cloud with reliable storage via replication. Storage overhead of replication is high and therefore it's going to be replaced with erasure codes. Despite the significant number of researches on...