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Total 21 records

    Dynamic based cost functions for TF/TA flights

    , Article 2005 IEEE Aerospace Conference, Big Sky, MT, 5 March 2005 through 12 March 2005 ; Volume 2005 , 2005 ; 1095323X (ISSN); 0780388704 (ISBN); 9780780388703 (ISBN) Malaek, S. M ; Kosari, A. R ; Jokar, S ; Sharif University of Technology
    2005
    Abstract
    A new methodology has been proposed which offers a systematic approach to use the so called "performance index" or cost function as the basic tool to incorporate the dynamics of the aircraft in the process of trajectory planning. Moreover, by using non-dimensional parameters a better understanding of the dynamic terms are provided. © 2005 IEEE  

    Total fuel reduction via formation flights: a new approach to air-corridor path optimization

    , Article AIAA AVIATION 2014 -14th AIAA Aviation Technology, Integration, and Operations Conference ; 2014 Asadi, F ; Malaek, S. M. B ; Sharif University of Technology
    Abstract
    This paper presents a new approach to better utilize international air-corridors for formation flights. Using Particle Swarm Optimization, we show how different long-range flights can be brought together to form a formation. The idea serves both to increase international air-corridor capacities together and to decrease fuel consumption up to 8-10%. Case studies show that there are many places which such an approach could effectively be implemented to help cope with increase in fuel price as well as the demand for aerial transport of passengers and goods  

    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
    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... 

    Estimating Air Travel Demand in Iran’s Domestic Routes

    , M.Sc. Thesis Sharif University of Technology Movaffagh Yami, Mostafa (Author) ; Fatemi Ardestati, Farshad (Supervisor) ; DadPay, Ali (Co-Advisor)

    Automatic Speech Recognition System for Pilot-Air Traffic Service Units Communications

    , M.Sc. Thesis Sharif University of Technology Azadmanesh, Mahsa (Author) ; Bahrani, Mohammad (Supervisor) ; Baba Ali, Bagher (Co-Advisor) ; Pazooki, Farshad (Co-Advisor)
    Abstract
    Currently, in the Islamic Republic of Iran, after aviation accidents and incidents, conversations between pilots and air traffic controllers are re-examined by the State Air Transport Organization of the Islamic Republic of Iran and turned into text. The Automatic Recognition System for Pilot-Air Traffic Service Units’ Communication helps in the implementation of speech recognition. Reducing the time and cost of converting conversations into texts and creating an aviation database in the country are other uses of this system. In this research, after collecting and refining the actual conversation between pilots and air traffic controllers and examining seven methods, we design a system that... 

    Modeling and Control of Dual Function Aviation Auxiliary Power Unit (APU)

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Alireza (Author) ; Ghorbanian, Kaveh (Supervisor)
    Abstract
    Auxiliary Power Unit (APU) is a single spool turboshaft engine aimed to start the main gas turbine engine on the ground as well as to supply the necessary power to the auxiliary and electrical equipment during an engine emergency shut down. Similar to the main gas turbine engine, the performance of APU depends on the altitude. Hence, a control system with an appropriate logic is required for a dual function APU which provides electrical power as well as pressurized air through a generator and load compressor, respectively. It should be emphasized that while the output of the generator remains almost not affected with the altitude, the performance of the load compressor is altered by this.... 

    Aerodynamics Design of Aviation High-speed Radial Turbine with a Feasibility on Cooling

    , M.Sc. Thesis Sharif University of Technology Zolfaghari Nasab Hajizadeh, Abolfazl (Author) ; Ghorbanian, Kaveh (Supervisor)
    Abstract
    Radial turbines with small dimensions and in small power capacities are of great interest. In general, turbine performance improvement and higher output power may be achieved through increasing the inlet mass flow rates however at the expense of more weight and larger dimensions. On the other hand, increasing the inlet total temperature to the turbine will result in higher power potentials. Nevertheless, the turbine needs to be cooled in case that the intended inlet temperature goes beyond the turbine material limitation. In this thesis, radial turbine equations are reviewed and the logic of a 1D algorithm is developed where parameters like the total temperature, total pressure, and mass... 

    Heterogeneity in preferences of air travel itinerary in a low-frequency market

    , Article Transportation Research Record ; Issue 2214 , 2011 , Pages 10-19 ; 03611981 (ISSN) Rezaei, A ; Puckett, S. M ; Nassiri, H ; Sharif University of Technology
    2011
    Abstract
    Research in the choice behavior of air travelers has evolved to include an analytical focus on variation in the sensitivities of travelers to factors influencing itinerary choice. Some choice studies have moved beyond a focus on assumed representative, mean-level sensitivities toward a goal of representing the distribution of preferences across a sample. The mixed multinomial logit model has served as a valuable means of estimating such distributions of air travel preferences, including studies of business travelers, impacts of airport level-of-service attributes, distributions of willingness-to-pay (WTP), and information-processing strategies. Does the insight gained in previous studies,... 

    Exhaust soot investigation in a JP combustor working at various wall temperatures

    , Article AIAA Aerospace Sciences Meeting, 2018, 8 January 2018 through 12 January 2018 ; Issue 210059 , 2018 ; 9781624105241 (ISBN) Schneider, G. E ; Ghafourizadeh, M ; Darbandi, M ; Saidi, M. H ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA  2018
    Abstract
    In this study, a jet propulsion JP combustor is studied numerically to investigate the combustor wall temperature influences on the soot characteristics emitted at its exhaust. There are a number of ways to control the combustor wall temperatures benefiting from different wall cooling technologies. Irrespective of using different high technology cooling systems, it is important to recognize how the wall temperature can affect the soot emission from one specific JP engine. Before examining the main combustor, it is important to assess the accuracy of the computational fluids dynamics (CFD) tool via solving a benchmark problem. In this regard, the predicted flame structure for the benchmark... 

    Effect of active feather length on aerodynamic performance of airfoils at low reynolds number flow

    , Article AIAA AVIATION 2020 FORUM, 15 June 2020 through 19 June 2020 ; Volume 1 PartF , 2020 Esmaeili, A ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA  2020
    Abstract
    To increase the flight endurance of a Micro air vehicle (MAVs), which operates at low Reynolds number flow, one way is to harvest energy during its flight. By inspiring from the nature when all the birds use their feathers to control and distribute their power along the flying time, a solution might be design of a piezoelectric plate as feathers, which scavenges energy directly from the fluid flow. Cantilevered beam with piezo-ceramic layer undergoing vortex-induced vibrations can convert the mechanical energy available from the ambient environment to a usable electrical power. Since a flow-driven piezoelectric composite beam takes a form of natural three-way coupling of the turbulent fluid... 

    Frequency planning of GSM cellular communication network in urban areas including traffic distribution, a practical implementation

    , Article 2008 Asia-Pacific Symposium on Electromagnetic Compatibility and 19th International Zurich Symposium on Electromagnetic Compatibility, APEMC 2008, Suntec, 19 May 2008 through 23 May 2008 ; 2008 , Pages 891-894 ; 9810806280 (ISBN); 9789810806286 (ISBN) Atamanesh, M ; Farzaneh, F ; Sharif University of Technology
    2008
    Abstract
    Using an in-house developed software the signal level, the best server cells, and the amount of interference using standard propagation models are determined in a cellular environment. The program is also able to assign the frequency channels automatically to the TRXs taking into account the carrier to interference and the traffic distribution using a genetic algorithm. In this paper, the cost function is based on the total Carrier to Interference ratio (C/I) and the traffic density of the serving area. The software by means of a genetic algorithm approaches a frequency assignment which increases the overall quality of service throughout the cellular network. The package has been used in a... 

    An integrated virtual environment for feasibility studies and implementation of aerial MonoSLAM

    , Article Virtual Reality ; Volume 16, Issue 3 , September , 2012 , Pages 215-232 ; 13594338 (ISSN) Amiri Atashgah, M. A ; Malaek, S. M. B ; Sharif University of Technology
    2012
    Abstract
    This work presents a complete framework of an integrated aerial virtual environment (IAVE), which could effectively help implementing MonoSLAM (single-camera simultaneous localization and mapping) on an aerial vehicle. The developed system allows investigating different flight conditions without using any preloaded maps or predefined features. A 3D graphical engine integrated with a full 6 DOF aircraft dynamic simulator together with its trajectory generator completes the package. The 3D engine generates and accumulates real-time images of a general camera installed on the aerial vehicle. We effectively exploit C++ to develop the 3D graphics engine (3DGE) and all its associated visual... 

    Accounting for systematic influences on preference heterogeneity in air travel

    , Article Transportation Research Record ; Issue 2300 , 2012 , Pages 147-154 ; 03611981 (ISSN) Rezaei, A ; Puckett, S. M ; Sharif University of Technology
    2012
    Abstract
    Modeling passengers' itinerary choice behavior helps in understanding the increasingly competitive airline market and in predicting air travel demand. Recently, investigation of the variation in passengers' preferences with regard to factors influencing their choice through estimation of the mixed multinomial logit model has received attention. An extended form of the model identifies sources of heterogeneity and consequently makes the choice models less restrictive in considering both systematic and random preference variation across individuals. This research investigates the existence of significant interactions between passengers' preference heterogeneity around the mean of random... 

    Radiative heat transfer modeling in numerical simulation of a heavy duty steam generator

    , Article 54th AIAA Aerospace Sciences Meeting, 2016, 4 January 2016 through 8 January 2016 ; 2016 ; 9781624103933 (ISBN) Darbandi, M ; Abrar, B ; Barezban, M. B ; Schneider, G.E ; Shamsaei, Y ; Nematollahi, M ; Sharif Universty of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA 
    Abstract
    The proper modeling of radiation is of great importance in numerical simulation of combustion processes. A simple gray weighted-sum-of-gray-gases (WSGG) model has been intensively used in CFD simulations of industrial combustion applications, mainly because of its low computational costs. However, the gray assumption is far from the real behavior of non-gray combustion gases. This could consequently affect the accuracy of temperature field and heat flux distribution predictions. On the other hand, modern non-gray global radiation models such as the standard spectral line-based weighted-sum-od-gray-gases (SLW) model are still computationally expensive for many engineering purposes. To... 

    The effect of soot nano-particles injection on two-phase smoke aerosol formation in a kerosene-fired burner

    , Article 54th AIAA Aerospace Sciences Meeting, 2016, 4 January 2016 through 8 January 2016 ; 2016 ; 9781624103933 (ISBN) Darbandi, M ; Ghafourizadeh, M ; Schneider, G. E
    American Institute of Aeronautics and Astronautics Inc, AIAA 
    Abstract
    Feeding a laboratory furnace with the gaseous kerosene, the resulting two-phase turbulent flame is simulated to study the effects of injecting soot nano-particles into the inflow air on the emissions of smoke aerosol, CO, and CO2species pollutants, and the resulting radiation heat transfer. We use our past experiences in aerosol modeling of soot nano/micro particles in turbulent nonpremixed flames burning simple hydrocarbon fuels and extend them to study the effects of injecting gaseous kerosene on the aforementioned parameters. To model the evolutionary process of soot nanoparticle formation, i.e., the nucleation, coagulation, surface growth, and oxidation, we employ a two-equation soot... 

    The effects of baffle plate on soot nano-aerosol and pollutant productions in a JP-fueled combustor

    , Article 54th AIAA Aerospace Sciences Meeting, 2016, 4 January 2016 through 8 January 2016 ; 2016 ; 9781624103933 (ISBN) Darbandi, M ; Ghafourizadeh, M ; Schneider, G. E ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA  2016
    Abstract
    In this paper, the effects of a baffle plate on flame deflection and its throttling are investigated numerically in a combustor consuming jet propellant JP. We study the plate effects on the resulting soot volume fraction, soot particles diameter, mass fractions of carbon monoxide (CO), carbon dioxide (CO2), and benzene (C6H6). We use a two-equation turbulence model, a PAH-inception two-equation soot model imposing oxidation due to OH agents, a detailed chemical kinetic consisting of 121 species and 2613 elementary reactions, and the flamelet combustion model to perform the current study. We also take into account the turbulence-chemistry interaction using the presumed-shape probability... 

    Design of a mechanically closed-loop test rig for testing aviation industry’s gearboxes

    , Article Aviation ; Volume 21, Issue 4 , 2017 , Pages 132-142 ; 16487788 (ISSN) Mozafari, S ; Rezazadeh Mohamadi, M ; Dolatkhah Takloo, S ; Mardani, M ; Sharif University of Technology
    Abstract
    Due to the wide usage of rotary equipment and the necessity of their testing for maintenance and repair, test rigs have become necessary. The mechanical closed-loop test rig developed in Sharif University of Technology branch of ACECR (Academic Centre of Education, Culture and Research) is a test rig with low energy losses that is suitable for testing high power gearboxes such as aerospace or wind turbine gearboxes. It can be loaded up to 489Hp at a maximum speed of 3000 rpm, and the test components can be tested in different testing conditions including a variety of torques and speeds. This paper describes the preliminary, conceptual, and detailed design, steps including frame work design,... 

    Towards IoT-driven predictive business process analytics

    , Article 2020 International Conference on Omni-layer Intelligent Systems, COINS 2020, 31 August 2020 through 2 September 2020 ; 2020 Elhami, E ; Ansari, A ; Farahani, B ; Aliee, F. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    Predictive business process monitoring is concerned with predicting the process-related Key Performance Indicators (KPIs) and forecasting the future behavior of the process in realtime. Despite the amount of work contributed by researches to this field of research, the performance of existing solutions is not desirable for practical settings. Indeed, these approaches are typically context-unaware and lack generality. However, in real-life use cases, business processes are not isolated from the surrounding working environment, and thus they are influenced by many contextual events, such as events generated by IoT devices. To the best of our knowledge, there is no comprehensive study... 

    Study and optimization of amino acid extraction by emulsion liquid membrane

    , Article Separation Science and Technology ; Volume 43, Issue 11-12 , 2008 , Pages 3075-3096 ; 01496395 (ISSN) Mohagheghi, E ; Alemzadeh, I ; Vossoughi, M ; Sharif University of Technology
    2008
    Abstract
    A batch extraction of an essential amino acid, phenylalanine, from an aqueous solution of different concentrations by an Emulsion Liquid Membrane (ELM) was developed using D2EHPA as a cationic carrier, Span 80 as the surfactant, paraffin, and kerosene as the diluents, and HCl as the internal electrolyte. All effective parameters such as the initial pH of the aqueous external phase, the electrolyte concentration in the aqueous internal phase, carrier, and surfactant concentration in the emulsion, the volume ratio of the organic to aqueous internal phase (Roi), the volume ratio of the W/O emulsion to the aqueous external phase (Rew) and time were examined and optimized using the Taguchi... 

    Simulation and visualization environment for nonlinear helicopter flight dynamics

    , Article General Aviation Technology Conference and Exhibition, Wichita, KS, 29 August 2006 through 31 August 2006 ; 2006 ; 01487191 (ISSN) Nasiri, M ; Rezazade, M ; Sharif University of Technology
    SAE International  2006
    Abstract
    The Analytic 6 D.O.F. dynamic model of a helicopter is developed for 3D computer generated imagery simulator. Analytic expressions for the forces and moments on the various helicopter components are derived. By using the forces and moments equilibrium, helicopter trim point is determined using Newton's method of solving the nonlinear set of trim equations. The equations of motion for the fuselage six degree of freedom are assembled by applying Newton's law of motion relating the applied forces and moments to the resulting translational and rotational acceleration. Visual C++ programming software, utilized as a platform will interact to MATLAB Aircraft Instrument ActiveX and 3DSTATE for...