Search for: process-design
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    Adaptive CFAR processor for nonhomogeneous environments

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 36, Issue 3 PART 1 , 2000 , Pages 889-897 ; 00189251 (ISSN) Ali, M ; Mohammad, K ; Bastani, H ; Sharif University of Technology
    A new constant false alarm rate (CFAR) processor is presented, that exhibits a noticeable detection performance in the presence of interfering targets, as well as an excellent false alarm rate (FAR) regulation at the clutter power transition regions. The presented CFAR processor, which is designed to work on the logarithmic amplified video signals, can also easily adapt itself to new environmental conditions. Furthermore, in the steady state, its performance does not depend on the background noise power. Simulation results show the obvious preference of the presented processor to the conventional GOCA-LOG/CFAR, regarding FAR regulation at the clutter power transition regions. Noncoherent... 

    Pilot plant and their rule in chemical industries

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Babazadeh, F ; Haddadi, A. M ; Kazemini, M ; Sharif University of Technology
    With regard to petrol, petrochemical and chemical industries extension in Iran and with regard to growth of agreements in these field and huge investment payments for different engineering activities and technology transfer, we need to evaluate each of these projects essentially and scientifically to reach the success. For this purpose we need to investigate the chain from science to market. On of the middle cycle of the chain are pilot plants, which have key rule for success of project. In this work after introducing pilot plant and explanation of their aims and characteristics, we allude the rule and situation of pilot plant for getting technology and transfer in chemical industries and... 

    Experimental evaluation of Master/Checker architecture using power supply- and software-based fault injection

    , Article Proceedings - 10th IEEE International On-Line Testing Symposium, IOLTS 2004, Madeira Island, 12 July 2004 through 14 July 2004 ; 2004 , Pages 239-244 ; 0769521800 (ISBN); 9780769521800 (ISBN) Rajabzadeh, A ; Miremadi, S. G ; Mohandespour, M ; Sharif University of Technology
    This paper presents an experimental evaluation of the effectiveness of the Master/Checker (M/C) architecture in a 32-bit Pentium® processor system using both power-supply disturbance (PSD) fault injection and software-implemented fault injection (SWIFI) methods. A total of 6000 faults were injected in the Master processor to measure the error detection coverage of the Checker processor. The results of the experiments with PSD fault injection show that the error detection coverage of the M/C architecture is about 66.13%, which is not quite effective. This low coverage depends on the high rate of Master processor hangs because of voltage fluctuation. The coverage increased to about 99.73% when... 

    A low-voltage low-power switched-capacitor filter using a new transistor configuration

    , Article 12th International Conference on Microelectronics, ICM 2000, 31 October 2000 through 2 November 2000 ; Volume 2000-October , 2000 , Pages 99-102 ; 9643600572 (ISBN) Lotfi, R ; Atarodi, S. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2000
    A novel cascode configuration previously presented as a high output resistance load (Fujimori and Sugimoto, 1998) has been investigated and utilized for amplification to achieve higher gain and bandwidth by the authors (Lofti and Atarodi, Proc. ICEE'00, vol.1, pp.83-8, 2000). A low-voltage single-stage opamp using this configuration is designed. Finally, based on this idea a 1.5-V offset- and gain-compensated 5th order switched-capacitor low pass filter with only 150 μA current consumption in a 0.8 μm process is designed. © 2000 IEEE  

    Multi-objective design and operation of Solid Oxide Fuel Cell (SOFC) Triple Combined-cycle Power Generation systems: Integrating energy efficiency and operational safety

    , Article Applied Energy ; Volume 185 , 2017 , Pages 345-361 ; 03062619 (ISSN) Sharifzadeh, M ; Meghdari, M ; Rashtchian, D ; Sharif University of Technology
    Elsevier Ltd  2017
    Energy efficiency is one of the main pathways for energy security and environmental protection. In fact, the International Energy Agency asserts that without energy efficiency, 70% of targeted emission reductions are not achievable. Despite this clarity, enhancing the energy efficiency introduce significant challenge toward process operation. The reason is that the methods applied for energy-saving pose the process operation at the intersection of safety constraints. The present research aims at uncovering the trade-off between safe operation and energy efficiency; an optimization framework is developed that ensures process safety and simultaneously optimizes energy-efficiency, quantified in... 

    Rigorous Synthesis of Optimal Heat Integrated Complex Column Sequences Using Genetic Algorithm

    , M.Sc. Thesis Sharif University of Technology Baroughi, Amir Hossein (Author) ; Bozorgmehri, Ramin (Supervisor) ; Farhadi, Fathollah (Supervisor)
    Finding the optimal heat integrated distillation column sequence is an utmost important optimization problem in process engineering. The frequently used approach in this area is to obtain a suitable sequencing candidate and then accomplish the heat integration based on the application of Pinch technology to finalize the design. This approach reduces the problem complexity at the expense of not necessarily reaching the best possible result. This work follows a genetic super structure approach to systematic and rigorous synthesis of optimal multi-component distillation sequences (including simple and thermally coupled complex columns) and simultaneously heat exchanger networks by using a... 

    Design and Operation of Proper Freeze Drying Process to Recover Active Biological Agent

    , M.Sc. Thesis Sharif University of Technology Saadat, Mohammad Mahdi (Author) ; Rosta Azad, Reza (Supervisor)
    One of the most important unit operations in the production of dry powder biological products involves a freeze dryer apparatus. In this process, Liqueur, which is containing the α-amylase enzyme, undergoes a frigidity condition in which loses its moisture during sublimation. Under these circumstances, applying an adequate supply of sublimation enthalpy without raising the temperature of the frigid material up to melting, plays an important role in the quality of the product and preventing degradation of the α-amylase enzyme. Freeze drying depends on two main factors; time and energy. Furthermore, it is necessary to obtain an optimal temperature and pressure for different steps and... 

    Robust tolerance design of mechanical assemblies using a multi-objective optimization formulation

    , Article SAE Technical Papers ; Vol. 1 , 2014 Khodaygan, S ; Movahhedy, M. R ; Sharif University of Technology
    The design process always has some known or unknown uncertainties in the design variables and parameters. The aim of robust design is minimization of performance sensitivity to uncertainties. Tolerance allocation process can significantly affect quality and robustness of the product. In this paper, a methodology to minimize a product's sensitivity to uncertainties by allocating manufacturing tolerances is presented. The robust tolerance design problem is formulated as a multi-objective optimization based on the combined function-uncertainty-cost model. Genetic algorithm is utilized to solve the multi-objective optimization and a case study is presented to illustrate the methodology  

    Optimal control of an aerial tail sitter in transition flight phases

    , Article Journal of Aircraft ; Volume 53, Issue 4 , Volume 53, Issue 4 , 2016 , Pages 914-921 ; 00218669 (ISSN) Banazadeh, A ; Taymourtash, N ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc 
    The main purpose of this study is to generate optimal transition trajectories for an aerial tail sitter that uses cross-coupled thrust-vectoring control. A transition maneuver is most challenging for such configurations due to coupling of the forces and moments with instability in the most critical low-speed flight phases. Based on the classical Cauchy method, an improved gradient-based algorithm is developed in a collaborative process in order to find transition trajectories and increase the convergence rate. The cost function is defined in terms of minimum time in transition from hover to cruise and minimum altitude variations from cruise to hover. In addition, physical constraints are... 

    Nonlinear oscillation and stability analysis of the turning process with a worn tool

    , Article Proceedings of the ASME Design Engineering Technical Conference, 30 August 2009 through 2 September 2009 ; Volume 1, Issue PARTS A AND B , 2009 , Pages 927-934 ; 9780791848982 (ISBN) Moradi, H ; Ahmadian, M. T ; Bakhtiari Nejad, F ; Sharif University of Technology
    Self-excited and forced vibrations are important topics in machining processes because their occurrence results in poor surface finish, increase in tool wear and hampers productivity. In this paper, turning process is modeled as a SDOF dynamic system including quadratic and cubic structural nonlinearities. The effect of tool flank wear, as a contact force between the work-piece and tool, is addressed vigorously. Multiple scale method is used to find the solution of the nonlinear dynamic equation including regenerative chatter, forced excitation and tool wear. It is shown that, width of cut can be considered as the bifurcation parameter of the system. Primary, super-harmonic and sub-harmonic... 

    Introducing a novel method for improving the design of off-grid photovoltaic systems

    , Article 2019 Smart Gird Conference, SGC 2019, 18 December 2019 through 19 December 2019 ; 2019 ; 9781728158945 (ISBN) Davoudi, M ; Moeini Aghtaie, M ; Mosaddegh, H. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Using the potential of off-grid photovoltaic systems is a feasible way to supply electrical energy to locations which are far from the national electricity grid. In the design process of these systems, it is important to choose an appropriate capacity of these panels, since it should be able to steadily supply energy in all-weather conditions, especially cloudy days. In the conventional algorithm to design these panels and determine the capacity of these photovoltaic arrays, the number of cloudy days is not considered. Thus, in this papers, a new method is introduced in order to find out the appropriate capacity of off-grid photovoltaic arrays in the planning process of these systems. © 2019... 

    A new method for design cycle period management in aircraft design process

    , Article Aircraft Engineering and Aerospace Technology ; Volume 80, Issue 5 , 5 September , 2008 , Pages 497-509 ; 00022667 (ISSN) Soltanmohammad, S ; Malaek, S. M ; Sharif University of Technology
    Purpose - The purpose of this paper is to present research into reducing the aircraft design cycle period, by reducing the necessary number of design cycle iterations. The design cycle period is one of the main characteristics of the design process and design cycle iterations play a major role in the design cycle period. Design/methodology/approach - Toachieve the above-mentioned goal, the paper presents a mathematical model of iterations for the aircraft design process. This model describes the design coupled tasks as a discrete-linear time invariant dynamic system. This model also helps identify tasks which are the most important for generating iterations. This new method basically helps... 

    An efficient multi-band spectral subtraction method for robust speech recognition

    , Article 2007 9th International Symposium on Signal Processing and its Applications, ISSPA 2007, Sharjah, 12 February 2007 through 15 February 2007 ; 2007 ; 1424407796 (ISBN); 9781424407798 (ISBN) Safayani, M ; Sameti, H ; Babaali, B ; Manzuri Shalmani, M. T ; Sharif University of Technology
    In this paper we present a novel approach for adjusting a multi band spectral subtraction filter coefficients based on speech recognition system results. Currently most speech enhancement techniques are designed according to various waveform level criteria such as maximizing SNR or minimizing signal error. However improvement in these criteria does not necessarily result in increasing speech recognition performance. Only if these methods generate sequence of features that maximize or increase the likelihood of the correct transcription relative to other incorrect competing hypotheses, speech recognition performance will increase. Here we use an utterance with a known transcription and... 

    Designing an infinite channel server

    , Article Scientia Iranica ; Volume 13, Issue 1 , 2006 , Pages 78-82 ; 10263098 (ISSN) Haji, A. R ; Haji, R ; Akhavan Niaki, S. T ; Sharif University of Technology
    Sharif University of Technology  2006
    In this paper, the designing of a parallel channel queuing system is considered in which it is desirable to serve the customers immediately upon their arrival. To design such a service facility, the first and the second moments of the number of customers are obtained in an infinite channel server under the assumption that the arrival process has a general probability structure and the service times of customers are independent and identically distributed random variables. With the knowledge about the above two moments, one can obtain the approximate number of channels such that the queue length becomes zero. © Sharif University of Technology, January 2006  

    A novel matrix based systematic approach for vulnerability assessment

    , Article COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering ; Volume 40, Issue 1 , 2021 , Pages 1-17 ; 03321649 (ISSN) Sabouhi, H ; Doroudi, A ; Fotuhi Firuzabad, M ; Bashiri, M ; Sharif University of Technology
    Emerald Group Holdings Ltd  2021
    Purpose: This paper aims to propose a novel matrix-based systematic approach for vulnerability assessment. Design/methodology/approach: The proposed method consists of two major steps. First, the power network is modeled as a topological combination of edges (transmission lines, transformers, etc.) and nodes (buses, substations, etc.). The second step is to use an axiomatic design-based index for topology analysis. This index is based on the systematic counting of possible routes from the start (generators) to destination (loads), considering load importance, before and after a disruption. Findings: The effectiveness of the proposed method is demonstrated through an illustrative example and... 

    Aircraft design cycle time reduction using artificial intelligence

    , Article Aerospace Science and Technology ; Volume 26, Issue 1 , 2013 , Pages 244-258 ; 12709638 (ISSN) Azizi Oroumieh, M. A ; Malaek, M. B. S ; Ashrafizaadeh, M ; Taheri, M. S ; Sharif University of Technology
    In this work we show how Artificial Intelligence (AI) could effectively be used to expedite the decision making process in the early stages of the aircraft design process. We employ both Fuzzy Logic (FL) and Neural Network (NN) as two different schemes of the AI. The developed tools are intended to help to select the proper combination of engine thrust, wing area and the aircraft weight without going through elaborate details of other direct approaches. We further show how the AI could be applied to the specific class of light business jets which serves to validate these schemes. The results indicate the effectiveness of the AI approach in the preliminary aircraft design process. The actual... 

    Multi-layer hybrid wired-cum-wireless sensor network design

    , Article International Journal of Communication Networks and Distributed Systems ; Volume 9, Issue 3-4 , 2012 , Pages 286-310 ; 17543916 (ISSN) Maleki, S ; Sepehri, M. M ; Farvaresh, H ; Nayebi, A ; Sawhney, R ; Sharif University of Technology
    Sensor networks with sensing, data processing and communicating capabilities have a broad spectrum of applications. Based on application requirements, various network configurations can be designed. One such robust configuration is a hybrid wired-cum-wireless sensor network that is composed of a wireless sensor network and a wired backbone which are inter-connected via access points. In this paper, the joint problem of configuring a hybrid wired-cum-wireless sensor network, position-constrained cluster head and access point placement is proposed. The design considers real wireless communication limitations, optimum locations of access points and cluster heads, and hybrid transmission... 

    Evolutionary design of optimum distillation column sequence

    , Article Canadian Journal of Chemical Engineering ; Volume 90, Issue 4 , 2012 , Pages 956-972 ; 00084034 (ISSN) Boozarjomehry, R. B ; Laleh, A. P ; Svrcek, W. Y ; Sharif University of Technology
    Synthesis of the optimum distillation column sequence (DCS), which incorporates a huge search space composed of both conventional and complex arrangements, is a highly complicated combinatorial problem in the field of chemical process design and optimisation. In this study, a novel procedure for the synthesis of optimum DCS proposed by Boozarjomehry et al. [Boozarjomehry et al., Can. J. Chem. Eng. 87, 477-492 (2009)] is expanded to include the complex distillation arrangements. The method is based on evolutionary algorithms, and the total annual cost (TAC) is the main criterion used to screen alternatives. Efficient procedure has been proposed for encoding mechanism to include and classify... 

    A 6-bit digital phase shifter by using HEMT technology

    , Article Proceedings - 2012 IEEE 8th International Colloquium on Signal Processing and Its Applications, CSPA 2012 ; 2012 , Pages 29-32 ; 9781467309615 (ISBN) Ameri, S. H ; Sabaghi, M ; Pourhossien, A ; Kouchaki, M ; Rahnama, M ; Sharif University of Technology
    A 6-bit passive phase shifter for S frequency band has been designed in a standard HEMT technology. A new switched-network topology has been proposed for implementing the 5.625 phase shift step which these digital bits are series with each other. We used Advanced Design System (ADS2010) to perform simulations. These digital bits will produce 64 different mode phase shift of -177.15 to +177.15 degree. In all cases simulation obtained less than 1 % error  

    Inherently safe and economically optimal design using multi-objective optimization: The case of a refrigeration cycle

    , Article Process Safety and Environmental Protection ; Volume 104 , 2016 , Pages 254-267 ; 09575820 (ISSN) Eini, S ; Shahhosseini, H. R ; Javidi, M ; Sharifzadeh, M ; Rashtchian, D ; Sharif University of Technology
    Institution of Chemical Engineers  2016
    The economic viability of industrial processes strongly depends on their safe and reliable operation. The method of inherent safe process design enables systematic consideration of safety measures in order to ensure process safe operation at the early stages of process design. The challenge is that the economic measures that are often considered for the design of industrial processes are often incommensurable with the safety measures. In the present research, a novel framework is proposed in which the safety criteria are quantified based on consequence modeling and aggregated with the economic performance using multi-objective optimization programming. The developed methodology was applied...