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design-process
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Iteration Control in Design Process
, Ph.D. Dissertation Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
The main goal of this research is to reduce 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. To achieve the above mentioned goal, we present 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 break information cycles that create iterations among important tasks....
Dynamic based cost functions for TF/TA flights
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 48, Issue 1 , 2012 , Pages 44-63 ; 00189251 (ISSN) ; Kosari, A. R ; Sharif University of Technology
Abstract
In this work we present a systematic approach to incorporating the dynamic capabilities of an aircraft via suitable cost functions while planning for terrain following-terrain avoidance trajectories. We further show that use of nondimensional parameters related to the dynamics of an aircraft within the cost function provides a better understanding of how they could affect the resulting trajectories. Different case studies for arbitrary three-dimensional flights show that the current approach provides more realistic trajectories and so helps alleviate the design process of relevant controllers as well as tracking systems over the desired terrain. We further introduce two new parameters of...
Robust tolerance design of mechanical assemblies using a multi-objective optimization formulation
, Article SAE Technical Papers ; Vol. 1 , 2014 ; Movahhedy, M. R ; Sharif University of Technology
Abstract
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
Control of a four-switch rectifier under unbalanced input voltage
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2014 , p. 261-266 ; Javadian, V ; Shahbazi, M ; Zolghadri, M. R ; Sharif University of Technology
Abstract
Nowadays, reduced switch rectifiers are more interested because of less expense. Control of these rectifiers is an important part of their designing process. In this paper, a method is proposed for four-switch rectifier to continue working under unbalanced input voltage. To achieve this goal, first a method is introduced to separate positive and negative sequences of dq components. Also, the necessary condition is determined. Considering this condition, the control method is modified and new reference value for the control signals is calculated. Finally, the system is simulated in Simulink and the results are provided. These results confirm the accuracy of the developed model, and also the...
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) ; Moeini Aghtaie, M ; Mosaddegh, H. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
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...
Axiomatic design of step down DC/DC converter
, Article 2008 IEEE International Conference on Industrial Technology, IEEE ICIT 2008, Chengdu, 21 April 2008 through 24 April 2008 ; 2008 ; 9781424417063 (ISBN) ; Haddadi, A ; Khaligh, A ; Sharif University of Technology
2008
Abstract
In this paper, the axiomatic design is introduced for designing the power electronic converters. The main idea of axiomatic design is to introduce variables affecting the desired performances of the system most independently possible. The design process is presented for a Buck converter. ©2008 IEEE
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) ; Malaek, S. M ; Sharif University of Technology
2008
Abstract
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) ; Sameti, H ; Babaali, B ; Manzuri Shalmani, M. T ; Sharif University of Technology
2007
Abstract
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...
Design and synthesis of AKAM: A RISC asynchronous microprocessor
, Article 2007 International Conference on Intelligent and Advanced Systems, ICIAS 2007, Kuala Lumpur, 25 November 2007 through 28 November 2007 ; 2007 , Pages 1318-1323 ; 1424413559 (ISBN); 9781424413553 (ISBN) ; Rasooli, A ; Jafarpour, B ; Sharif University of Technology
2007
Abstract
Asynchronous microprocessors are more flexible to adapt to physical parameters, and have lower power consumption than synchronous microprocessors. In this paper we will introduce the design of an asynchronous microprocessor (V8-uRISC) and explore its design process compared to synchronous design. The processor is synthesized by Persia, an automatic tool for synthesizing asynchronous circuits. We have performed full functional test at various levels of design and synthesis. Our results show that an area overhead is expected for the asynchronous design as the cost for lower power and more robustness. ©2007 IEEE
RS-Satellites propulsion subsystem performance sizing via design plane technique, a generic method
, Article IEEE Aerospace and Electronic Systems Magazine ; Volume 36, Issue 2 , 2021 , Pages 56-70 ; 08858985 (ISSN) ; Kosari, A ; Malaek, S. M. B ; Khoshsima, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Remote sensing satellites propulsion subsystem preliminary design based on performance sizing is discussed. The process is a fairly complicated one considering a variety of operational as well as performance requirements. This research aims to reduce the number of iterations required by the current practice to reach a compromise. It is based on a rapid-sizing method that helps lessen lengthy iteration cycles. The proposed technique, similar to such class of preliminary design processes, leads to an acceptable approximation that must be properly conveyed to other disciplines involved for further elaborations. With proper selection of design and performance parameters together with fundamental...
RS-Satellites propulsion subsystem performance sizing via design plane technique, a generic method
, Article IEEE Aerospace and Electronic Systems Magazine ; Volume 36, Issue 2 , 2021 , Pages 56-70 ; 08858985 (ISSN) ; Kosari, A ; Malaek, S. M. B ; Khoshsima, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Remote sensing satellites propulsion subsystem preliminary design based on performance sizing is discussed. The process is a fairly complicated one considering a variety of operational as well as performance requirements. This research aims to reduce the number of iterations required by the current practice to reach a compromise. It is based on a rapid-sizing method that helps lessen lengthy iteration cycles. The proposed technique, similar to such class of preliminary design processes, leads to an acceptable approximation that must be properly conveyed to other disciplines involved for further elaborations. With proper selection of design and performance parameters together with fundamental...
Online exams and the COVID-19 pandemic: a hybrid modified FMEA, QFD, and k-means approach to enhance fairness
, Article SN Applied Sciences ; Volume 3, Issue 10 , 2021 ; 25233971 (ISSN) ; Shabani, S ; Sharif University of Technology
Springer Nature
2021
Abstract
COVID-19 pandemic caused an increasing demand for online academic classes, which led to the demand for effective online exams with regards to limitations on time and resources. Consequently, holding online exams with sufficient reliability and effectiveness became one of the most critical and challenging subjects in higher education. Therefore, it is essential to have a preventive algorithm to allocate time and financial resources effectively. In the present study, a fair test with sufficient validity is first defined, and then by analogy with an engineering product, the design process is implemented on it. For this purpose, a hybrid method based on FMEA, which is a preventive method to...
Recuperator Design of a 100kW Aviation Gas Turbine and its Integrated Performance Analysis with the Aircraft
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
The increasing need for more efficient and environmentally friendly microturbines necessitates the utilization of compact recuperators resulting in lower fuel consumption and emissions. The goal of this research is to determine the performance behavior of a primary surface recuperator to be incorporated in a 100 kW microturbine. Primary surface recuperator, known for relatively favorable characteristics in heat transfer, low weight, and high efficiency is considered as a candidate in aviation engines. In this research, a computational model for heat transfer and pressure losses is used for the design optimization of annular involute-profile cross wavy primary surface recuperators in...
Aircraft design cycle time reduction using artificial intelligence
, Article Aerospace Science and Technology ; Volume 26, Issue 1 , 2013 , Pages 244-258 ; 12709638 (ISSN) ; Malaek, M. B. S ; Ashrafizaadeh, M ; Taheri, M. S ; Sharif University of Technology
2013
Abstract
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...
Optimum design process of vibration absorber via imperialist competitive algorithm
, Article International Journal of Structural Stability and Dynamics ; Volume 12, Issue 3 , 2012 ; 02194554 (ISSN) ; Salehipoor, H ; Sharif University of Technology
Abstract
This paper deals with the optimum design of vibration absorbers utilized to reduce undesirable random vibrational effects that are originated in linear structures. Analytical expressions, for the case of nonstationary white-noise accelerations, are derived. The criterion is different from most conventional optimum design criteria, since it is based on minimizing the displacement or the acceleration variance of the main structure responses, without considering performances required against failure. In this study, in order to control the structural vibrations induced on a mechanical structure excited by nonstationary based acceleration random process, the MOO (multi-objective optimum) design...
Introducing a novel method for materials selection in mechanical design using Z-transformation in statistics for normalization of material properties
, Article Materials and Design ; Volume 30, Issue 10 , 2009 , Pages 4396-4404 ; 02641275 (ISSN) ; Abedian, A ; Manshadi, B. D ; Khabbaz, R. S ; Sharif University of Technology
Elsevier
2009
Abstract
Optimum materials selection is a very important task in design process of every product. There are various materials selection methods like Ashby's method or digital logic methods such as DL and MDL. In the present research work the Z-transformation method is proposed for scaling the material properties to overcome the shortcoming of MDL method. The results show that despite the simple scaling function used, the ranking procedure is as powerful as MDL method and even it is superior to MDL when it ranks the less important materials existing among a list of candidate materials
Applications of axiomatic design theory in design for human safety in manufacturing systems: a literature review
, Article MATEC Web of Conferences, 13 September 2017 through 15 September 2017 ; Volume 127 , 2017 ; 2261236X (ISSN) ; Houshmand, M ; Fatahi Valilai, O ; Slatineanu L ; Sharif University of Technology
Abstract
Design for Human Safety (DfHS) is an approach to integrate knowledge of human safety in the design process. DfHS is multi-disciplinary in its nature, requiring many kinds of information and knowledge. Number of DfHS studies tried to apply Axiomatic Design (AD) to achieve their aims. The purpose of this paper is to review the literature on application of AD in DfHS in manufacturing systems and to propose a roadmap for future DfHS works. This paper examines the number and type of publications dealing with this context. The review covers papers published between 1990 (when AD was introduced first) and 2017. It is based on a range of combinations of the following keywords: "Axiomatic design" and...
Feeder growth: a new method for automatic optimal feeder design in gravity casting processes
, Article Structural and Multidisciplinary Optimization ; Volume 39, Issue 5 , 2009 , Pages 519-530 ; 1615147X (ISSN) ; Davami, P ; Sharif University of Technology
2009
Abstract
The optimal feeder design in gravity casting processes is considered. The design problem is formulated as an additive, growth-like, evolutionary topology optimization problem. The initial design of the presented method is a casting part which is placed in a suitable environmental mould box. The method is composed of three stages: determining the feeder-neck connection point on the casting surface, constructing the feeder-neck and the feeder growth. During the growth stage, the feeder topology is changed gradually until satisfying some predefined criteria. The design of multiple feeders is also considered in this work. In the presented method, feeders are designed in a descending order of...
Unsteady three dimensional aerodynamic load prediction using neural networks
, Article 2007 International Joint Conference on Neural Networks, IJCNN 2007, Orlando, FL, 12 August 2007 through 17 August 2007 ; 2007 , Pages 1995-1999 ; 10987576 (ISSN) ; 142441380X (ISBN); 9781424413805 (ISBN) ; Ghorbanian, K ; Gholamrezaei, M ; Amiralaei, M. R ; Sharif University of Technology
2007
Abstract
The focus of the current research is to develop an intelligent design process that uses existing data as a tool for the designers, one that fully utilizes the ability of the computer to interpolate and extrapolate the scattered data. Surface pressure measurements were conducted for a pitch oscillation wing in a subsonic closed circuit wind tunnel. Experimental results have been used to train a multilayer perceptron network. This work indicates that neural networks can reliably predict aerodynamic coefficients and forecast the effects of reduced frequencies on the wind turbine blade performance. ©2007 IEEE
New seepage-related design graphs for rock-fill dams
, Article International Symposium on Dams in the Societies of the 21st Century, ICOLD-SPANCOLD - Dams and Reservoirs, Societies and Environment in the 21st Century, Barcelona, 18 June 2006 through 18 June 2006 ; Volume 1 , 2006 , Pages 971-978 ; 0415404231 (ISBN); 9780415404235 (ISBN) ; Jafarzadeh, F ; Sharif University of Technology
Taylor and Francis/ Balkema
2006
Abstract
Seepage analysis serves as one of the most significant stages in the design process of an embankment dam. In two-dimensional (2D) seepage analysis of embankment dams, little or no attention is paid to the widthwise flows from side abutments. Moreover, the role of grout curtain extensions into the side abutments and abutment material properties are inevitably neglected when performing seepage analyses in 2D plane. In this paper, two and three-dimensional (3D) models of a rock-fill dam are generated and several unsteady and steady state seepage analyses are performed using finite element method (FEM). The results obtained from 2D and 3D seepage analyses were compared with measurements from the...