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oroojlooy-jadid--afshin
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Train timetabling on double track and multiple station capacity railway with useful upper and lower bounds
, Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3324-3344 ; 10263098 (ISSN) ; Eshghi, K ; Sharif University of Technology
2017
Abstract
Train scheduling has been one of the significant issues in the railway industry in recent years since it has an important role in efficacy of railway infrastructure. In this paper, the timetabling problem of a multiple-tracked railway network is discussed. More specifically, a general model is presented here in which a set of operational and safety requirements is considered. The model handles the trains overtaking in stations and considers the stations' capacity. The objective function is to minimize the total travel time. Unfortunately, the problem is NP-hard, and real-sized problems cannot be solved in an acceptable amount of time. In order to reduce the processing time, we presented some...
Train Timetabling Optimization in Metro Networks
, M.Sc. Thesis Sharif University of Technology ; Koorosh, Eshghi (Supervisor)
Abstract
Train scheduling is a significant issue in the railway industry in recent years because it has an important role in railway infrastructure. In this paper, the timetabling problem of a multiple tracked railway network is discussed. More specifically, a general model with specific attention to “Tehran Metro” is presented here in which a set of operational and safety requirements are also considered. The model handles the trains overtaking in a station and innovatively considers the capacity of stations. An objective function is to minimize the total travel time. The problem is NP-hard so the real size problem cannot be solved in acceptable amount of time. In order to reduce the processing time...
Study of stochastic sequence-dependent flexible flow shop via developing a dispatching rule and a hybrid GA
, Article Engineering Applications of Artificial Intelligence ; 2012 , Pages 494-506 ; 09521976 (ISSN) ; Fatemi Ghomi, S. M. T ; Oroojlooy Jadid, A ; Sharif University of Technology
2012
Abstract
A flexible flow shop is a generalized flow shop with multiple machines in some stages. This system is fairly common in flexible manufacturing and in process industry. In most practical environments, scheduling is an ongoing reactive process where the presence of real time information continually forces reconsideration of pre-established schedules. This paper studies a flexible flow shop system considering non-deterministic and dynamic arrival of jobs and also sequence dependent setup times. The problem objective is to determine a schedule that minimizes average tardiness of jobs. Since the problem class is NP-hard, a novel dispatching rule and hybrid genetic algorithm have been developed to...
Panel Construction and Haplotype Phasing of Iranian Genomes using Multimodal Genomics Data
, M.Sc. Thesis Sharif University of Technology ; Motahari, Abolfazl (Supervisor)
Abstract
In recent decades, genetics has become one of the key pillars in medical and scientific research, and haplotype analysis plays a crucial role in understanding the genetic structure of populations. Haplotypes are specific combinations of alleles at different loci in the genome that are inherited together and provide valuable information about genetic history and intra-population diversity. One of the challenges in this field is the mismatch between the existing reference panels and the genetic characteristics of the Iranian population, as many of these panels have been developed based on data from non-Iranian populations. This mismatch can lead to incorrect results in genetic analyses. In...
Vibrational Analysis of Carbon Nanoscroll tubes
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Assempour, Ahmad (Supervisor)
Abstract
In recent year carbon nanostructures (CNS) has been the pinnacle of academic and industrial research. After development and refinement of better methods of controlled fabrication of high-quality CNS, these structures started substituting nanotubes in their renowned applications including nanochannels and nanocarriers. Due to the tunable core size of CNS using electric fields, they can be used as controlled ion channels and nanocarriers with controlled drug release as well as more dynamics oriented applications including nano-oscillators, nano-actuators and artificial muscle tissue. However lack of vibrational studies on CNS has hindered researchers in this path. In this thesis vibrational...
Linear analysis of the stability of particle-laden stratified shear layers
, Article Canadian Journal of Physics ; Vol. 92, issue. 2 , 2014 , pp. 103-115 ; ISSN: 00084204 ; Firoozabadi, B ; Afshin, H
2014
Abstract
Hydrodynamic instabilities at the interface of stratified shear layers could occur in various modes and have an important role in the mixing process. In this work, the linear stability analysis in the temporal framework is used to study the stability characteristics of a particle-laden stratified two-layer flow for two different background density profiles: smooth (hyperbolic tangent) and piecewise linear. The effect of parameters, such as bed slope, viscosity, and particle size, on the stability is also considered. The pseudospectral collocation method employing Chebyshev polynomials is used to solve two coupled eigenvalue equations. Based on the results, there are some differences in the...
Modeling and Identification of Fixed-Wing Aircraft Behavior using Dynamic Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
This thesis builds and validates a continuous-time neural model of fixed-wing flight using the Neural Ordinary Differential Equation framework. A Simulink-based analytic simulator of a Cessna 172 in cruise provides ground truth under step, doublet, and random excitations. The model preserves six analytical kinematics and learns six dynamic derivatives via channel-wise Neural ODE subnetworks from elevator, aileron, and rudder inputs with fixed throttle. Training follows a two-stage pipeline—derivative warm-up then adjoint-based continuous-time optimization with rollout—supported by Butterworth and Savitzky–Golay label denoising, input standardization, and robust target normalization. On...
Numerical simulation of density current using two-phase flow
, Article 2006 ASME Joint U.S.- European Fluids Engineering Division Summer Meeting, FEDSM2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2 FORUMS , 2006 , Pages 49-54 ; 0791847500 (ISBN); 9780791847503 (ISBN) ; Firoozabadi, B ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
Due to shear layer at the interface of density current and ambient fluid, density current disturbs and entrains the surrounding fluid. Most existing analytical and numerical models for density current flows are based on the equations for single-phase flows. In this research, the density current has been modeled with two-phase flow model. The governing equations are continuity, x- momentum, and y- momentum equations for every fluid. The volume-of-fluid (VOF) interface tracking technique which uses a piecewise-linear interface calculation (PLIC) in each cell is used to determine the deformation of free surface in density current, numerically. Surface tension is implemented by the continuous...
Numerical simulation of density current using two-phase flow
, Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) ; Firoozabadi, B ; Sharif University of Technology
2006
Abstract
Due to shear layer at the interface of density current and ambient fluid, density current disturbs and entrains the surrounding fluid. Most existing analytical and numerical models for density current flows are based on the equations for single-phase flows. In this research, the density current has been modeled with two-phase flow model. The governing equations are continuity, x- momentum, and y- momentum equations for every fluid. The volume-of-fluid (VOF) interface tracking technique which uses a piecewise-linear interface calculation (PLIC) in each cell is used to determine the deformation of free surface in density current, numerically. Surface tension is implemented by the continuous...
Adaptive Controller Design for Ducted Fans in Vertical Plane Phases
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
Ducted fan vertical take-off and landing (VTOL) aerial vehicles have drawn many attentions in the world because of their capability to offer high power to weight ratio for a certain vehicle diameter relative to open rotors or helicopters. However, due to inherent uncertainties in dynamics and inefficient and poor quality responses, significant control challenges are still unsolved and exciting fields for research. In the current study, a nonlinear dynamic model is proposed for the controller design purpose. This model is validated against simulation by performing several standard scenarios. An adaptive control method, named model reference (MRAC), is utilized to design a perfect controller...
The Role of Symmetry in Quantifying Information
, M.Sc. Thesis Sharif University of Technology ; Shafie, Afshin (Supervisor)
Abstract
In this thesis we want to discuss about a new approach about information. Using this approach, Scott Muller builds his formalism on two basic concepts: distinguishablity and symmetry. His claim is that there is an inverse relation between symmetry and information. It means that if we have a symmetric system we need less information (Than an asymmetric system) to describe it. Here, we are going to explore the role and significance of symmetry in probabilistic distributions of the double-slit experiment, and we want to show if there is a predetermined relation between symmetry and information or not.
Trajectory Optimization of Micromechanical Flying Insect
,
M.Sc. Thesis
Sharif University of Technology
;
Banazadeh, Afshin
(Supervisor)
Abstract
In this work, A new hybrid approach is presented to optimize a trajectory of Micromechanical Flying Insect in an obstacle reach environment. Here, a singleobjective Evolutionary Algorithm is utilize for finding solutions corresponding to multiple conflicting goals, which include minimizing the length of the path while maximizing safety margin by avoiding hard and non-moving obstacles. On the other hand, dynamic constraints of Micromechanical Insect such as maximum and minimum attitude angles and speed should be taken into account. In order to reduce the computational cost, a novel hybrid two-layer procedure is suggested for trajectory optimization. In the first layer, the algorithm generates...
Captive System Identification of Coanda-Effect Aerial Vehicle in Hover
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
Identification of dynamic behavior and extraction of mathematical model for aerial vehicle is important in design, test and evaluation processes. Due to explosion of unmanned vehicles industry in recent years, many innovative aerial concepts is introduced. Coanda-effect air vehicle is one of these novel ideas which is similar to flying saucers. In this study, an experimental scale model of this air vehicle is designed, built and tested with purpose of identifying the linear dynamic model of the vehicle, using the frequency domain identification methods. Performing the system Identification in hover requires a stable hovering capability in the vehicle. Given the inherent instabilities of...
The Role and Significance of the Concept of Information in Physical Phenomena
, Ph.D. Dissertation Sharif University of Technology ; Shafiee, Afshin (Supervisor)
Abstract
Undoubtedly, the concept of information has an outstanding role in our description of physical systems and biological processes. In the framework of pragmatic approach, information is a useful notion through which any physical event gets its significance. In this approach, information can be understood and recognized while it is capable of producing new information. Thus, the meaning of information depends on our recognition and understanding as conscious beings. Accordingly, the following question may arise: where is the role of conscious being in the emergence of physical properties in Nature? To answer this fundamental question, we first investigate how information enters the physics, in...
The Study of Chemistry in Space and Its Realtionship with Origin of Life
, M.Sc. Thesis Sharif University of Technology ; Shafiee, Afshin (Supervisor)
Abstract
In this study the concept of the origin of life, as an important question, is investigated and reviewed.Then the possibility of the beginning of life from an extraterrestrial origin is studied via spectroscopy methods to analyze the role of the cosmic waves.Moreover, by considering the similarity between the chirality of the essential amino acids and extraterrestrial amino acids, found in meteors the various methods for studying the structure of molecules, as well as the possibility of the transfer of the central elements of life from space to the earth are reviewed in details.Finally, we suggest how chirality might be emerged due to the interaction of the molecule with the environment,...
On Proposing New Thought Experiments in Quantum Domain
,
Ph.D. Dissertation
Sharif University of Technology
;
Shafiee, Afshin
(Supervisor)
Abstract
Although quantum mechanics has thrilled a multitude of successes since its birth, it has also generated puzzles that persist to this day. These puzzles are largely connected with the role of measurement in quantum mechanics. Therefore, we are dealing with individual phenomena and that our possibilities of handling the measuring instruments allow us only to make a choice between the different complementary types of phenomena. Within the framework of delayed-choice experiments, the choice between complementary types of phenomena is postponed to the moments after the preparation of system is a superposition state. Regarding the probability theory, we have concluded that the delayed-choice...
Minimum-Distance Collision-Free Trajectory Generation for Formation Flying Satellites Using a Hybrid Path-Planning Algorithm
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
The formation flight of satellites corresponds to a group of small satellites, performing the mission of a presumed larger and more expensive satellite. Usually mission designers tend to put these satellites in such orbital configurations that their trajectories do not intersect. Although a stable configuration in a certain collision-free orbit is desirable for long term purposes, most of the missions including maneuvers like forming or changing a configuration and inserting new satellites need to be planned using a proper path planning algorithm. In this thesis, a path planning algorithm is suggested that acquires the optimal and impact-free trajectories for a group of satellites for...
A Novel Approach to Multi Fidelity Multi-objective Conceptual Design Optimization of a Cloud Seeding UAV
, M.Sc. Thesis Sharif University of Technology ; Banazade, Afshin (Supervisor)
Abstract
In this project, process of conceptual design and design optimization is presented for a cloud seeding UAV. Inefficiency of classical and statical design approaches is more obvious in new designed missions restricted to different and numerous Dynamic and performance constraints with no similar design target aircraft. So in this project we used conceptual design optimization approach with respect to aerodynamic, weight and balance, performance and stability discipline to overcome those restrictions and to design a cloud seeding UAV. In order to reduce the computational time, we used low fidelity method (analectic equation) in performance and stability, medium fidelity method (empherical...
Stability Analysis of Nonlinear Periodically Time-Varying Dynamic Systems By Studying Typical Insect-Like Flapping Wing
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
Designing Nonautonomous periodic systems such as helicopters, multirotors, monocopters or the dynamics of flapping wings requires stability analysis and careful examination in order to identify and determine their dynamic behaviour. In practice, analysis and design are interdependent and the design of nonlinear control systems involves an iterative process. To know the importance of identifying and to accurately implement methods to analyse this kind of systems in the field of aerospace, the flapping wing can be a good example. The issue of stability and the control of the flapping wings have not yet had a clear solution, and the current research including controller design based on linear...
Adaptive Attitude and Position Control of a Rigid Body Insect-Like Flapping Wing
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
In this study, adaptive control of attitude and position of a rigid body insect-like flapping wing is investigated. For this purpose, a non-linear dynamic and time varying modeling and simulation is carried out initially with six degrees of freedom, and then the accuracy of the simulation is evaluated during different test cases. In order to design the controller, non-linear and time varying dynamic is transformed into non-linear and time-invariant dynamic using theory of averaging. Then, a non-linear controller is designed based on Lyapunov stability theory. Due to the inefficiency of the aforementioned controller under disturbances and unknown uncertainties in the model, an adaptive...