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    Investigating various effects of reformer gas enrichment on a natural gas-fueled HCCI combustion engine

    , Article International Journal of Hydrogen Energy ; Vol. 39, issue. 34 , November , 2014 , p. 19799-19809 Voshtani, S ; Reyhanian, M ; Ehteram, M ; Hosseini, V ; Sharif University of Technology
    Homogenous charge compression ignition (HCCI) combustion has the potential to work with high thermal efficiency, low fuel consumption, and extremely low NOx-PM emissions. In this study, zero-dimensional single-zone and quasi-dimensional multi-zone detailed chemical kinetics models were developed to predict and control an HCCI combustion engine fueled with a natural gas and reformer gas (RG) blend. The model was validated through experiments performed with a modified single-cylinder CFR engine. Both models were able to acceptably predict combustion initiation. The result shows that the chemical and thermodynamic effects of RG blending advance the start of combustion (SOC), whereas dilution... 

    A review of ignition delay and combustion characteristics of biodiesel fueled diesel engine

    , Article Applied Mechanics and Materials ; Volume 390 , 2013 , Pages 333-337 ; 16609336 (ISSN) ; 9783037858332 (ISBN) Qate, M ; Pourabdian, M ; Javareshkian, A ; Farzbod, A ; Sharif University of Technology
    Increasing rate of demanding biodiesel as alternative energy resource, persuade researchers to investigate engine performance of biodiesel-fueled engines, which are highly influenced by ignition delay (ID) and combustion characteristics of such a fuel. This review article introduces a literature review on ignition delay (ID) and combustion characteristics of diesel engine fueled with biodiesel. Slightly difference between combustion characteristics of bio fueled engine and petroleum diesel one recognized as result of carried out investigations. Early start of combustion (SOC) and shorter ID of biodiesel comparing to diesel is reported by most of investigations. Lower compressibility, higher... 

    On-line fault detection and isolation (FDI) for the exhaust path of a turbocharged SI engine

    , Article ASME 2013 Dynamic Systems and Control Conference, DSCC 2013 ; Volume 1 , 2013 ; 9780791856123 (ISBN) Salehi, R ; Shahbakhti, M ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    Detection and isolation of faults in the exhaust gas path of a turbocharged spark ignition (SI) engine is an essential part of the engine control unit (ECU) strategies to minimize exhaust emission and ensure safe operation of a turbocharger. This paper proposes a novel physics-based strategy to detect and isolate an exhaust manifold leakage and a closed-stuck wastegate fault. The strategy is based on a globally optimal parameter estimation algorithm which detects an effective hole area in the exhaust manifold. The estimation algorithm requires prediction of the exhaust manifold's input and output flows. The input flow is predicted by a nonlinear Luenberger observer which is analytically... 

    An analytical review of process-centered software engineering environments

    , Article Proceedings - 2012 IEEE 19th International Conference and Workshops on Engineering of Computer-Based Systems, ECBS 2012 ; 2012 , Pages 64-73 ; 9780769546643 (ISBN) Matinnejad, R ; Ramsin, R ; Sharif University of Technology
    Process-centered Software Engineering Environments, or PSEEs, are intended for the definition, modification, and enactment of software process models, they thus bring software development processes into effect. Even though research efforts in process-centered software engineering abound, PSEE technology has not received the attention that it deserves. In order to create a concise but effective and practically applicable evaluation framework for PSEEs, this paper first presents a survey of PSEEs and highlights the current state of the art of the technology. The PSEEs which have been reviewed herein have been regarded as software systems, and as such, have been characterized in terms of their... 

    Fabrication and characterization of electrospun poly-L-lactide/gelatin graded tubular scaffolds: Toward a new design for performance enhancement in vascular tissue engineering

    , Article Progress in Natural Science: Materials International ; Volume 25, Issue 5 , October , 2015 , Pages 405–413 ; 10020071 (ISSN) Yazdanpanah, A ; Tahmasbi, M ; Amoabediny, G ; Nourmohammadi, J ; Moztarzadeh, F ; Mozafari, M ; Sharif University of Technology
    Elsevier  2015
    In this study, a new design of graded tubular scaffolds have been developed for the performance enhancement in vascular tissue engineering. The graded poly-L-lactide (PLLA) and gelatin fibrous scaffolds produced by electrospining were then characterized. The morphology, degradability, porosity, pore size and mechanical properties of four tubular scaffolds (graded PLLA/gelatin, layered PLLA/gelatin, PLLA and gelatin scaffolds) have been investigated. The tensile tests demonstrated that the mechanical strength and also the estimated burst pressure of the graded scaffolds were significantly increased in comparison with the layered and gelatin scaffolds. This new design, resulting in an increase... 

    Sliding Mode Observers to Detect and Isolate Faults in a Turbocharged Gasoline Engine

    , Article SAE International Journal of Engines ; Volume 8, Issue 2 , April , 2015 , Pages 399-410 ; 19463936 (ISSN) Salehi, R ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
    SAE International  2015
    This paper presents a novel model-based algorithm which is able to detect and isolate major faults assigned to the gas exchange path of a gasoline engine both in the intake and exhaust sides. The diagnostics system is developed for detection and isolation of these faults: air leakage fault between the compressor and the air throttle, exhaust manifold pressure sensor fault, wastegate stuck-closed fault and wastegate stuck-open fault. Sliding mode observers (SMOs) are the core detection algorithms utilized in this work. A first order SMO is designed to estimate the turbocharger rotational dynamics. The wastegate displacement dynamics coupled to the exhaust manifold pressure dynamics is... 

    Real-time estimation of the volumetric efficiency in spark ignition engines using an adaptive sliding-mode observer

    , Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 229, Issue 14 , December , 2015 , Pages 1925-1933 ; 09544070 (ISSN) Hassani Monir, V ; Salehi, R ; Salarieh, H ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Proper operation of an engine requires accurate measurement or estimation of the engine's air charge provided to the control unit which reduces both the engine's fuel consumption and the emissions. The volumetric efficiency of the engine is a key variable in computations using the engine control unit to estimate the air charge using the speed-density equation. This paper presents a new approach for real-time estimation of the volumetric efficiency using the sliding-mode methodology. An adaptive sliding-mode observer is proposed which relies on measurements from the engine's conventional sensors. The observer is shown to estimate asymptotically the volumetric efficiency of the engine for... 

    Geometry optimization of a fibrous scaffold based on mathematical modelling and CFD simulation of a dynamic cell culture

    , Article Computer Aided Chemical Engineering ; Volume 38 , 2016 , Pages 1413-1418 ; 15707946 (ISSN); 9780444634283 (ISBN) Tajsoleiman, T ; Abdekhodaie, M. J ; Gernaey, K. V ; Krühne, U ; Kravanja, Z ; Bogataj, M ; Sharif University of Technology
    Elsevier B.V  2016
    In tissue engineering, the development of a tissue essentially depends on supply of an adequate amount of nutrients and the design of a proper biophysical micro-environment for cells. The limitation of the available initial number of cells, expensive substances and time consuming experiments are the main bottlenecks in this type of processes. In this regard, mathematical modelling and computational fluid dynamics simulation (CFD) are powerful tools to identify an efficient and optimized design by providing reliable insights of the process. This study presents a mathematical model and CFD simulation of cartilage cell culture under a perfusion flow, which allows not only to characterize the... 

    Vibration analysis for fault detection of automobile engine using PCA technique

    , Article 4th International Conference on Control, Instrumentation, and Automation, 27 January 2016 through 28 January 2016 ; 2016 , Pages 372-376 ; 9781467387040 (ISBN) Jafarian, K ; Darjani, M ; Honarkar, Z ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    Today condition monitoring using vibration analysis is not only used for simple proposes like bearings and gears fault detection but also it is used in hybrid motors and cars in automobile industry for detecting or anticipating faults. The main aim of this paper is using vibration analysis in automobile industry to detect and categorize faults appeared due to poppet valve clearance and incomplete combustion sometimes called misfiring phenomenon in internal combustion engine. So we used four accelerometers on OHV engine body for registering vibration signals. Then using PCA technique acquiring data were investigated. At the end we succeeded to classify and detect faults with a high ratio of... 

    Modeling and control of cell cycle

    , Article 3rd International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2009 ; 2009 ; 9781424429028 (ISBN) Azizi, A ; Seifipour, N ; Sharif University of Technology
    Applying engineering approaches to non-engineering systems such as biological systems has brought a new research filed to the surface. The sole purpose of this research is mathematical modeling the cell cycle control system in the fissionyeast cell using Ordinary Differential Equations (ODE).This paper, in fact, introduces the capabilities of engineering knowledge and engineering of control, in particular, in this field. ©2009 IEEE  

    Towards a generic framework for model-driven engineering of software process lines

    , Article ACM International Conference Proceeding Series, 31 August 2017 through 1 September 2017 ; Volume Part F130524 , 2017 ; 9781450348430 (ISBN) Agh, H ; Ramsin, R ; Rysavy, O ; Vranic, V ; Sharif University of Technology
    Situational Method Engineering (SME)1approaches help construct bespoke software development processes according to the specifications of the project at hand, but they are time-consuming and costly. A Software Process Line (SPrL) tackles this problem by allowing software processes to be constructed for specific project situations through reusing core process assets. Model-Driven Development (MDD) has been used for automating SPrL Engineering (SPrLE); however, existing model-driven SPrLE methods are deficient as to their coverage of key MDD features. We propose a novel model-driven SPrLE approach that aims to address these shortcomings; it can be regarded as a framework that specifies the... 

    Correction to: a lightweight signcryption scheme for defense against fragment duplication attack in the 6LoWPAN networks

    , Article Peer-to-Peer Networking and Applications ; 7 June , 2018 , Pages 1- ; 19366442 (ISSN) Nikravan, M ; Movaghar, A ; Hosseinzadeh, M ; Sharif University of Technology
    Springer New York LLC  2018
    The Publisher regrets an incorrect figure was placed in the pdf version of the article. © 2018 Springer Science+Business Media, LLC, part of Springer Nature  

    Roles of surface coverage increase and re-peening on properties of AISI 1045 carbon steel in conventional and severe shot peening processes

    , Article Surfaces and Interfaces ; Volume 11 , 2018 , Pages 82-90 ; 24680230 (ISSN) Maleki, E ; Unal, O ; Sharif University of Technology
    Elsevier B.V  2018
    Surface coverage as one of the most effective parameters of shot peening process has substantial influence on the functionality of the peened component. The aim of this study is to investigate the effects of surface coverage increase on the properties of treated specimens experimentally before and after re-shot peening. Different shot peening treatments from conventional to severe; were performed on the AISI 1045 steel. Microstructural observations and XRD measurements were applied to characterize the circumstance of microstructure changes. In order to investigate the mechanical properties, microhardness profiles were achieved, surface roughness was evaluated and the residual stresses... 

    On the uniform sampling of the web: An improvement on bucket based sampling

    , Article 2009 International Conference on Communication Software and Networks, ICCSN 2009, Macau, 27 February 2009 through 28 February 2009 ; 2009 , Pages 205-209 ; 9780769535227 (ISBN) Heidari, S ; Mousavi, H ; Movaghar, A ; Sharif University of Technology
    Web is one of the biggest sources of information. The tremendous size, the dynamicity, and the structure of the Web have made the information retrieval process of the web a challenging issue. Web Search Engines (WSEs) have started to help users with this matter. However, these types of application, to perform more effectively, always need current information about many characteristics of the Web. To determine these characteristics, one way is to use statistical sampling of the Web pages. In this kind of approaches, instead of analyzing a large number of Web pages, a rather smaller and more uniform set of Web pages is used. This research attempts to analyze the presented methods for... 

    Engineering students’ motivation to learn technical english in esp courses: investigating iranian teachers’ and students’ perceptions

    , Article RELC Journal ; 2019 ; 00336882 (ISSN) Jafari Pazoki, S ; Alemi, M ; Sharif University of Technology
    SAGE Publications Ltd  2019
    Needs analysis is the key step to designing relevant and useful courses in English for Specific Purposes (ESP), but finding ways to deliver needs in a motivating and interesting way is also paramount. Therefore, investigating students’ motivation to learn ESP is central in needs analysis. Few studies have investigated needs from the perspective of ESP learners’ motivation. Focussing on engineering fields at three Iranian state universities, this study aimed to identify factors that affect engineering students’ motivation for learning technical English in ESP courses. Using a mixed method design, this study was conducted in two phases. In the first phase, semi-structured interviews with 40... 

    Efficient VLSI layout of edge product networks

    , Article 4th IEEE International Symposium on Electronic Design, Test and Applications, DELTA 2008, Hong Kong, SAR, 23 January 2008 through 25 January 2008 ; 2008 , Pages 555-560 ; 0769531105 (ISBN); 9780769531106 (ISBN) Bakhshi, S ; Sarbazi Azad, H ; Sharif University of Technology
    The interconnection network between the processor cores in multiprocessors on chip has a crucial impact on the performance. Efficient VLSI layout area of such networks can result in lower costs and better performance. Layouts with more compact area can lead in shorter wires and therefore the signal propagation through the wires may take place in shorter time. In this paper, we study the VLSI layout bounds of a new product network, called the Edge Graph Product. Lower bounds are usually computed by the crossing number and bisection width of the topological graphs. For computing the bisection width and crossing number of the edge graph product, we use the obtained upper bound on maximal... 

    Automatic extraction of is-a relations in taxonomy learning

    , Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 17-24 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) Neshati, M ; Abolhassani, H ; Fatemi, H ; Sharif University of Technology
    Taxonomy learning is a prerequisite step for ontology learning. In order to create a taxonomy, first of all, existing 'is-a' relations between words should be extracted. A known way to extract 'is-a' relations is finding lexicosyntactic patterns in large text corpus. Although this approach produces results with high precision but it suffers from low values of recall. Furthermore developing a comprehensive set of patterns is tedious and cumbersome. In this paper, firstly, we introduce an approach for developing lexico-syntactic patterns automatically using the snippets of search engine results and then, challenge the law recall of this approach using a combined model, which is based on... 

    Performance evaluation of communication networks for parallel and distributed systems

    , Article Parallel Computing ; Volume 32, Issue 11-12 , 2006 , Pages 775-776 ; 01678191 (ISSN) Sarbazi Azad, H ; Ould Khaoua, M ; Zomaya, A. Y ; Sharif University of Technology

    On the distortion value of elections with abstention

    , Article Journal of Artificial Intelligence Research ; Volume 70 , 2021 , Pages 567-595 ; 10769757 (ISSN) Seddighin, M ; Latifian, M ; Ghodsi, M ; Sharif University of Technology
    AI Access Foundation  2021
    In Spatial Voting Theory, distortion is a measure of how good the winner is. It has been proved that no deterministic voting mechanism can guarantee a distortion better than 3, even for simple metrics such as a line. In this study, we wish to answer the following question: How does the distortion value change if we allow less motivated agents to abstain from the election? We consider an election with two candidates and suggest an abstention model, which is a general form of the abstention model proposed by Kirchgässner. Our results characterize the distortion value and provide a rather complete picture of the model. ©2021 AI Access Foundation  

    A new high-performance adaptive engine mount

    , Article JVC/Journal of Vibration and Control ; Volume 10, Issue 1 , 2004 , Pages 39-54 ; 10775463 (ISSN) Foumani, M. S ; Khajepour, A ; Durali, M ; Sharif University of Technology
    SAGE Publications Inc  2004
    In this paper, we introduce a new high-performance adaptive hydraulic engine mount. The mount is tuned to road and engine conditions by changing the length of the inertia track and effective decoupler area in low-frequency road and high-frequency engine excitations. A single actuator is used to tune the mount in both low-frequency and high-frequency regimes. Sensitivity analysis is used to show that changing the length of the inertia track and decoupler area is the most effective way to tune an adaptive mount. Numerical simulations indicate that the proposed design can significantly improve the performance of a passive hydraulic mount