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ranji--hassan
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The Necessary Condition of Fractional Optimal Control the Sense of Caputo
, M.Sc. Thesis Sharif University of Technology ; Hesaaraki, Mahmud (Supervisor)Making Electrolyte Lithium Batteries Using Ionic Liquids and Organic Solvents
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
In this work, butyl methylimidazolium tetrafluoroborate and butyl methylimidazolium hexafluorophosphate are used as ionic liquid and lithium perchlorate and lithium hexafluorophosphate as lithium salt. Dimethyl carbonate and propylene carbonate are used as solvent to prepare diffrent kinds of organic - ionic liquids solvent for lithium ion batterries. In preliminary expriment it was distinguished that in the mixture of organic solvent lithium hexaflourophosphat has more conductivity in comparison with lithium perchlorate. There for,in this work, all organic-ionic liquid solvent electrolytes are considered based on lithium hexaflourophosphat salt. Different compositions of organic-ionic...
Dynamic response of a flat plate subjected to compression force during vertical and oblique impacts with calm water
, Article Engineering Structures ; Volume 176 , 2018 , Pages 697-706 ; 01410296 (ISSN) ; Rahbar Ranji, A ; Haddadpour, H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
An existing hydroelastic model is extended for a flat plate subjected to a compression force with spiral spring boundary conditions during water entry. Both vertical and oblique impacts of the plate into calm water are investigated. A longitudinal strip of the plate is analyzed by fully coupling hydrodynamic pressure with elastic responses. Hydrodynamic pressure is determined by potential flow theory and plate deflections are expressed in terms of dry normal modes. The plate deflections are validated through comparison with available asymptotic models, semi-analytical and experimental results. The effect of compression force on the plate deflection is investigated at the midpoint considering...
Hydroelastic criterion for an inclined flat plate in vertical and oblique impacts
, Article Applied Ocean Research ; Volume 79 , 2018 , Pages 173-183 ; 01411187 (ISSN) ; Rahbar Ranji, A ; Haddadpour, H ; Sharif University of Technology
2018
Abstract
A two-dimensional semi-analytical model is applied for the analysis of hydroelastic effect during vertical and oblique impacts of flexible inclined plates with different boundary conditions (BCs). Hydrodynamic pressure is calculated using Wagner's theory and the structural deformation is presented as a linear combination of dry normal modes. A longitudinal strip is used as an approximation of the longitudinal bending of a plate. Model predictions are validated by comparing with the available experimental data, semi-analytical model, and asymptotic approaches for vertical and oblique impacts of the plate with different BCs. The water impact is analyzed with two viewpoints of rigid and...
Comments on “Hydroelastic impact of a horizontal floating plate with forward speed” [J. Fluids Struct. 60 (2016) 97–113]
, Article Journal of Fluids and Structures ; Volume 81 , 2018 , Pages 378-382 ; 08899746 (ISSN) ; Rahbar Ranji, A ; Haddadpour, H ; Sharif University of Technology
Academic Press
2018
Abstract
This comment concerns the mathematical errors in the recent work of Wang et al. (2016). The corrected equations are presented. Deflections and critical values of compressive force and forward speed are modified. © 2018 Elsevier Ltd
A hybrid model for simulation of fluid-structure interaction in water entry problems
, Article Physics of Fluids ; Volume 33, Issue 1 , 2021 ; 10706631 (ISSN) ; Rahbar Ranji, A ; Haddadpour, H ; Moghadas, H ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
A hydroelastic hybrid model is developed to simulate the fluid-structure interaction in water entry problems using the partitioned approach. The interactions between a flat plate and the water are modeled by a hydroelastic model using explicit and implicit couplings. Both couplings are unstable due to numerical instability associated with the fluid added mass. To overcome the instability, an extended Wagner's model is combined with the hydroelastic model, and a hybrid model is developed. The extended Wagner's model is the extension of the classical Wagner's model that is used to estimate the fluid inertial, damping, and restoring forces of a flexible plate within the potential flow theory....
Structural Design of a Launch Vehicle with Reusable First Stage
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Aerodynamics loads and aeroheating during reentry, are one of the challenging issues in designing One of the main challenges in the design and application of reusable spacecrafts is the aerodynamic and thermal loads acting on their structures during reentry into the atmosphere. For this reason, all the concepts/prototypes presented in the 20th century were either not fully reusable, or were partially canceled, or did not have economic justification. In this report, the aerodynamic loads on the first stage of a launch vehicle during the launch and return phases have been investigated. Due to the fact that the main part of the first stage of the vehicle includes fuel and oxidizer tanks, the...
Optimal Trajectory Correction for Hazardous Near-Earth Asteroids
,
M.Sc. Thesis
Sharif University of Technology
;
Zohoor, Hassan
(Supervisor)
;
Sayyadi, Hassan
(Supervisor)
Abstract
The collision of moderately large asteroids and comets also referred to as Near-Earth Objects (NEO's) with earth would have catastrophic consequences. Such events have occurred in the past and may occur again in the future. However, for the first time in known history, humanity may have the technology required to counter this threat. Methods studied for mitigation of this hazard are based on deflecting asteroid's trajectory and are normally divided into two basic categories: high energy impulsive methods, and long-duration low-thrust methods. Two parts of mission to be optimized are the trajectory of spacecraft to reach the target and the deflection strategy which could be analyzed by the...
Control of Car-Like Multi Robots for Following and Hunting of Moving Target
, M.Sc. Thesis Sharif University of Technology ; Sayyaadi, Hassan (Supervisor) ; Salarieh, Hassan (Co-Advisor)
Abstract
The main purpose of the present thesis is to establish a decentralized controller for some car–like multi robots to follow and hunt moving targets. Robots are very similar to actual cars considering geometric dimensions, mass and moment of inertia and so on; and outputs of the controller are steering-wheel and driving-wheel torques appropriately. Dynamics of the moving target is so that it escapes from the robots. Robots are equipped with antenna for getting wireless sensory signals, including range and bearing sensors. Kalman filter is used for estimation the target relative position and speed and robots state variables. The controller is designed for doing the above mentioned group...
A revised version of ACO for cutting stock problem [electronic resource]
, Article International Journal of Industrial Engineering ; Vol 15, No 4 (2008), Pages 341-348 ; Javanshir, Hassan ; Sharif University of Technology
Abstract
The one-dimensional cutting stock problem has many applications in industries and during the past few years has been one of the centers of attention among the researchers in the field of applied operations research. In this paper, a revised version of Ant Colony Optimization (ACO) technique is presented to solve this problem. This paper is a sequel to the previous ACO algorithm presented by the authors. In this algorithm, according to some probabilistic rules, artificial ants will select cutting patterns and generate a feasible solution. Computational results show the high efficiency and accuracy of the proposed algorithm for solving one- dimensional cutting stock problem
Knowledge Management Application in Developing Marketing Management
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hassan (Supervisor)
Abstract
In recent years the advent of internet and web has transformed the process of data collection and make organizational and environmental data more accessible. On the one hand, many organizations have realized that the knowledge in these huge databases is key to supporting the various organizational decisions. Particularly, the knowledge about customers from these databases is critical for the marketing function. But, much of this useful knowledge is hidden and untapped. On the other hand, the intense competition and increased choices available for customers have created new pressures on marketing decision-makers and there has emerged a need to manage customers in a long-term relationship....
Hydrodynamic Modeling of an AUV
, M.Sc. Thesis Sharif University of Technology ; Sayyadi, Hassan (Supervisor)
Abstract
Autonomous underwater vehicles (AUVs) are a type of marine vehicles which are currently being used for exploration, maintenance, repairing of marine structures and military appliances. Unmanned underwater vehicles categorize in two types: ROVs and AUVs, ROVs (remotely operated vehicles) usually are connected to the mother vessel with a cable, conduction signals transfer through this cable and there is an operator in the control loop. The vehicle may be fed up with this cable, AUVs are modern underwater vehicles which the operator on controlling and conducting is removed, there is no connection between the vehicle and mother vessel, energy sources and controlling orders are set up in the...
Aeroelasticiy of Supersonic Wing Made of Functionally Graded Materials Using Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
The aeroelastic behavior of wings made of functionally graded materials in supersonic flow is studied. For this purpose the flutter speed is calculated and in the next step the post flutter behavior is investigated. The structural model is based on the classical plate theory and material properties are assumed to be graded in the thickness direction according the power law distribution in terms of the volume fraction of material constituents. The linear piston theory which is modified to include thickness effects is used for supersonic aerodynamic modeling. The nonlinear structural model based on the Von-Karman strains is considered for prediction of the post-flutter behavior of the wing....
Solving the P-Center Problem under Uncertainty
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hassan (Supervisor)
Abstract
Facility location decisions play a prominent role in strategic planning of many firms, companies and governmental organizations. Since in many real-world facility location problems, the data are subject to uncertainty, in this thesis, we consider the P-center problem under uncertainty of demand nodes. Using Bertsimas and Sim approach, we modeled the problem as a linear optimization model. Furthermore, we develop a tabu search algorithm to solve the problem. Finally we designed some experiments to adjust the parameters of tabu search algorithm. We presented the numerical result accordingly
Developing a Fuzzy Expert System Based on a Hybrid Artificial Intelligence Model for Sales Forecasting Modeling
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hassan (Supervisor)
Abstract
Success in forecasting and analyzing sales for a given good or service can mean the difference between profit and loss for an accounting period and, ultimately, the success or failure of the business itself. Therefore reliable prediction of sales becomes a very important task. This thesis presents a novel sales forecasting approach by integration of Genetic Fuzzy Systems (GFS) and Data Clustering to construct a sales forecasting expert system. At first, we use stepwise regression analysis (SRA) to determine factors which have most influence on sales. At the next stage we divide our raw data into k clusters by means of K-means algorithm. Finally, all clusters will be fed into independent...
Nonlinear Distributed-Parameters Vibration Analysis of an AFM Microcantilever Beam in Dynamic Mode
, Ph.D. Dissertation Sharif University of Technology ; Zohoor, Hassan (Supervisor)
Abstract
Dynamic and vibration behavior of AFM microcantilever beam subject to the tip-sample interaction and/or contact is systematically investigated. An Euler-Bernoli microcantilever in 2D plane is considered with longitudinal and bending displacements. Inextensibility assumption and extended Hamilton’s principle is utilized to extract the single-variable integro partial equation of motion under: 1) tip-nanoparticle interactions, 2) tip-surface interactions in non-contact mode and 3) tip-surface interactions and contacts in intermittent-contact mode. Galerkin’s first mode approximation is then used to discretize the derived equations; and multiple time scales method is adopted to analyze the...
Aeroelastic Analysis of Aircraft Composite Wings in a Compressible Flow
, M.Sc. Thesis Sharif University of Technology ; haddadpour, Hassan (Supervisor)
Abstract
In this research, an anistropic thin-walled beam composite is used to consider the effects of fiber orientation and lay-up configuration on the aeroelastic stability and response of an aircraft wing. The circum ferentially asymmetric stiffness (CAS) model consists of a group of non-classical effects; such as transverse shear, material anisotropic, warping inhibition, etc. The aerodynamic load has been modeled based on the strip theory and compressible unsteady flow in the finite- state form. In addition, to form the mass, stiffness and damping matrices of non-conservative aeroelastic systems the extended Galerkin’s method (EGM) and the method of separation of variables has been used. After...
Seismic Retrofit of Reinforced Concrete Columns With Post-Tensioned Metal Strips
, Ph.D. Dissertation Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
This thesis presents the results of an experimental and analytical study on the application of the strapping technique for seismic retrofit of reinforced concrete columns. In this technique, the columns are externally confined by post-tensioned metal strips. In the first phase of the experiments, the compressive stress-strain behavior of strapped cylindrical and prismatic specimens was studied. Effects of several parameters were studied including shape and size of specimens, strength of plain concrete, mechanical characteristics of confining strips and the level of pre-tensioning of the strips. The second phase of the tests included studying the lateral performance of strapped RC columns....
Assessment of Performance Based Behavior of Steel Moment Resisting Frames
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
In order to reduce structural and nonstructural damages and associated financial losses during intense seismic events such as Bam earthquake, seismic retrofitting of existing structures should be considered as a special issue. In this regard, for quantifying the seismic performance of structures a guideline termed “instruction for seismic rehabilitation of existing building No.360” is issued which is mainly borrowed from performance-based assessment procedures FEMA 356. In contrast to conventional seismic design methods which are based on controlling stress ratio for different load combinations, in performance-based earthquake engineering methodology, the displacement control of structural...
Historical Alert Analysis in Host-based Intrusion Detection
, M.Sc. Thesis Sharif University of Technology ; Abolhassani, Hassan (Supervisor)
Abstract
In the last decade, Intrusion Detection Systems has attracted attention due to their importance in network security, but still they've shortcomings. Generating a lot of low level alerts is the main problem. Many of these alerts are actually false positives. One suggested solution is Alert Correlation Analysis. Because of false positives alert correlation techniques are not able to build accurate scenarios, but the accuracy of alerts can be verified with the aid of the information logged in the host systems. In this dissertation after surveying the current alert correlation techniques, a model will be introduced to effectively verify the generated alerts and to apply correlation techniques to...