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modeling-and-optimization
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Total 167 records
Dynamic Simulation of the Biped Normal and Amputee Human Gait
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Zohour, Hassan (Supervisor)
Abstract
One of the best methods of gait analysis is to use analytical models. In this project, first, the normal human gait was simulated using a two-dimensional biped model with 7 segments, i.e., a HAT segment representing head, arms and trunk, and 6 segments representing thighs, shanks and feet of the two legs. The foot-ground contact was simulated using a five-point penetration contact model. The elastic impact and friction effects are considered in the ground reaction force modeling. Optimization of the normal human walking model provided constant coefficients for simple PD controllers’ (driving torque) equations that could reasonably reproduce the normal kinematical pattern. Then, in the second...
Dynamic Simulation of Running Human Normal and with Below-Knee Prosthesis
, M.Sc. Thesis Sharif University of Technology ; Firoozbakhsh, Keykhosro (Supervisor) ; Zohoor, Hassan (Supervisor)
Abstract
Researches in the field of human gait have a lot of applications in medicine, ergonomics, sport science and technology. Lower limb prostheses design is one of the fields in which human gait is important. One of the best methods of gait analysis is to use analytical models. In this project, first, the normal human was simulated using a two-dimensional biped model with 7 segments, i.e., a HAT segment representing head, arms and trunk, and 6 segments representing thighs, shanks and feet of the two legs. In this model the foot-ground contact was is estimated using Taylor series after running experiment and it’s analysis which is expendable to people with different ages and different weight and...
Static and dynamic neural networks for simulation and optimization of cogeneration systems
, Article 2006 ASME 51st Turbo Expo, Barcelona, 6 May 2006 through 11 May 2006 ; Volume 4 , 2006 , Pages 615-623 ; 0791842398 (ISBN); 9780791842393 (ISBN) ; Khaledi, H ; Ghofrani, M. B ; The International Gas Turbine Institute ; Sharif University of Technology
2006
Abstract
In this paper, the application of neural networks for simulation and optimization of the cogeneration systems has been presented. CGAM problem, a benchmark in cogeneration systems, is chosen as a case study. Thermodynamic model includes precise modeling of the whole plant. For simulation of the steady sate behavior, the static neural network is applied. Then using dynamic neural network, plant is optimized thermodynamically. Multi layer feed forward neural networks is chosen as static net and recurrent neural networks as dynamic net. The steady state behavior of CGAM problem is simulated by MFNN. Subsequently, it is optimized by dynamic net. Results of static net have excellence agreement...
Neural network prediction model of three-phase fluids flow in heterogeneous porous media using scaling analysis
, Article Journal of Petroleum Science and Engineering ; Volume 138 , 2016 , Pages 122-137 ; 09204105 (ISSN) ; Alizadeh, M ; Rafiee, J ; Moshirfarahi, M. M ; Sharif University of Technology
Elsevier
Abstract
Scaling analysis of fluid displacement in porous media is a reliable, fast method to evaluate the displacement performance of different oil production processes under various conditions. This paper presents the scaling studies of multiphase fluid flow through permeable media with a special attention to the three-phase immiscible water alternating gas (WAG) flooding under conditions prevailing in many oil reservoirs. The investigations are performed on a heterogeneous reservoir to study in detail the sensitivity of the displacement process to the scaling groups using various combinations of the process controlling parameters. The procedure of Inspectional analysis (IA) was utilized to...
Increasing the resilience of distribution systems against hurricane by optimal switch placement
, Article 2017 Electrical Power Distribution Networks Conference, EPDC 201717 August 2017, Article number 8012732, Pages 7-11 ; 2017 , Pages 7-11 ; 9781538630105 (ISBN) ; Abbaspour, A ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
Abstract
Due to increasing the intensity and frequency of natural disasters in recent years, power system decision makers are seeking cost efficient methods to improve the resilience of power grids against low probability, high impact natural disasters such as hurricanes, floods, and earthquakes. In this paper, a new algorithm is presented for switch placement problem with the main goal of improving the resilience of distribution grids. To reach this goal, at first, a model is presented to simulate the effects of hurricane on availability of system components. Then, this model is involved in optimization model of switch placement problem. A new criterion is introduced as objective function of switch...
Economic production quantity model with scrapped items and limited production capacity
, Article Scientia Iranica ; Volume 17, Issue 1 E , 2010 , Pages 58-69 ; 10263098 (ISSN) ; Najafi, A. A ; Akhavan Niaki, S.T ; Sharif University of Technology
2010
Abstract
In this paper, an Economic Production Quantity (EPQ) model is studied, in which the production defective-rate follows either a uniform or a normal probability distribution. Shortages are allowed and take a backorder state, and the existence of only one machine causes a limited production capacity for the common cycle length of all products. The aim of this research is to determine the optimal production quantity of each product, such that the expected total cost including holding, shortage, production, setup and defective items cost is minimized. The mathematical model of the problem is derived, for which the objective function is proved to be convex. Then, a derivative approach is utilized...
Intelligent optimal feed-back torque control of a 6DOF surgical rotary robot
, Article 11th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2020, 4 February 2020 through 6 February 2020 ; 2020 ; Ebrahimi Toulkani, N ; Zhilakzadeh, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Sophisticated surgeons are widely indicating the use of surgical robots in order to reject human error, increase precision, and speed. Among well-known robotic mechanisms, parallel robots are broadly more investigated regarding their special characters as higher acceleration, speed, and accuracy, and less weight. Specific surgical procedures confine, and restrict their workspace, while controlling and validating the robots are complicated regarding to their complex dynamic. To this end, in this paper, a 6-DOF robot, with rotary manipulators, is designed and controlled. Addressing nonlinearity of parallel robots, an innovative methodology is formulated to robustly penalize the error of...
Dynamics of bistable initially curved shallow microbeams: Effects of the electrostatic fringing fields
, Article IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM ; July , 2014 , p. 1279-1283 ; Yazdiو M. H ; Pishkenariو H. N ; Sharif University of Technology
Abstract
Effects of fringing electrostatic fields on the behavior of a double clamped initially curved microbeam are investigated. Galerkin's decomposition method is applied on the governing Euler-Bernoulli equation with distributed electrostatic force to obtain the lumped-parameter model of the system. The resulting single degree of freedom model is obtained with the Palmer's formula as a model for the fringing field effects. To derive an applied form of the fringing field effect in lumped model, we have used Genetic Algorithms as an optimization method. Then using the lumped model, we have investigated the system nonlinear dynamics. Comparison of the obtained bifurcation diagrams with the...
Comparative evaluation of advanced gas turbine cycles with modified blade cooling models
, Article 2006 ASME 51st Turbo Expo, Barcelona, 6 May 2006 through 11 May 2006 ; Volume 4 , 2006 , Pages 537-546 ; 0791842398 (ISBN); 9780791842393 (ISBN) ; Khaledi, H ; Hajilouy Benisi, A ; Sharif University of Technology
2006
Abstract
Advanced gas turbine cycles use advanced blade cooling technologies to reach high turbine inlet temperature. Accurate modeling and optimization of these cycles depend on blade cooling model. In this study, different models have been used to simulate gas turbine performance. The first model is the continuous model and the second is stage-by-stage model with alternative methods for calculating coolant, stagnation pressure loss and SPR. Variation of specific heat and enthalpy with temperature are included in both models. The composition of gas stream in turbine is changed step by step due to air cooling. These models are validated by two case study gas turbine results, which show good agreement...
Multi-objective planning model for integration of distributed generations in deregulated power systems
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 34, Issue 3 , 2010 , Pages 307-324 ; 10286284 (ISSN) ; Ehsan, M ; Sharif University of Technology
2010
Abstract
This paper presents a long-term dynamic multi-objective model for distributed generation investment. The proposed model optimizes three objectives, namely active losses, costs and environmental emissions and determines the optimal schemes of sizing, sitting of DG units and specially the dynamics of investment over the planning period. The Pareto optimal solutions of the problem are found using a GA algorithm and finally a fuzzy satisfying method is applied to select the optimal solution considering the desires of the planner. The solutions of Pareto optimal front are analyzed to extract general useful information for planners about the appropriate DG technologies and placement schemes. The...
Performance study of a supersonic inlet in the presence of a heat source
, Article Scientia Iranica ; Volume 18, Issue 3 B , 2011 , Pages 375-382 ; 10263098 (ISSN) ; Farahani, M ; Sepahi Younsi, J ; Sharif University of Technology
2011
Abstract
The flow over a supersonic inlet has been investigated experimentally and numerically at a free stream Mach number of 2 and a zero degree angle of attack. Wind tunnel tests were performed to obtain the performance parameters of the inlet and were used as a baseline and validation tools for the numerical code. A heat source was added to the flow field at a distance ahead of the inlet. The effect of heat source addition on the main performance parameters of the inlet is investigated numerically. Results show that the heat source considerably reduces drag coefficient; however, its effect on pressure recovery is not favorable. This unfavorable effect was then minimized by controlling heat source...
New approach for strategic bidding of gencos in energy and spinning reserve markets
, Article Energy Conversion and Management ; Volume 48, Issue 7 , 2007 , Pages 2044-2052 ; 01968904 (ISSN) ; Ranjbar, A. M ; Shirani, A. R ; Sharif University of Technology
2007
Abstract
In restructured and de-regulated power systems, generating companies (Gencos) are responsible for supplying electricity for both energy and reserve markets, which usually operate simultaneously. In this condition, the question is how much and for what price must each Genco generate for each market to maximize its profit, so this paper intends to answer to this question. In this paper, first, the combined energy and reserve markets are considered, and the Nash equilibrium points are determined. Then, the bidding strategies for each Genco at these points will be presented. The bids for the energy and 10 min spinning reserve (TMSR) markets are separated in the second stage, and again, the...
A new approach for bidding strategy of gencos using particles swarm optimization combined with simulated annealing method
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 3 , 2007 , Pages 303-315 ; 03601307 (ISSN) ; Ranjbar, A. M ; Bagheri Shouraki, S ; Shirani, A. R ; Sadati, N ; Sharif University of Technology
2007
Abstract
This paper describes a procedure that uses particle swarm optimization (PSO) combined with the simulated annealing (SA) to analyze the bidding strategy of Generating Companies (Gencos) in an electricity market where they have incomplete information about their opponents. In the proposed methodology, Gencos prepare their strategic bids according to the Supply Function Equilibrium (SFE) model and they change their bidding strategies until Nash equilibrium points are obtained. Nash equilibrium points constitute a central solution concept in the game theory and are computed with solving a global optimization problem. In this paper a new computational intelligence technique is introduced that can...
A new structure for electricity market scheduling
, Article 2006 International Conference on Power Electronics, Drives and Energy Systems, PEDES '06, New Delhi, 12 December 2006 through 15 December 2006 ; 2006 ; 078039772X (ISBN); 9780780397729 (ISBN) ; Ranjbar, A. M ; Shirani, A. R ; Sharif University of Technology
2006
Abstract
On pool market structure, the generating units are typically dispatched in order of lowest to highest bid as needed to meet demand requirement as well as considering network constraints. Generally, no account is taken of generating unit's reliability when scheduling them. This paper proposes a new structure for electricity market to consider generating unit's reliability in the scheduling problem. GAMS (General Algebraic Modeling System) language has been used to solve the social welfare maximization problem using CPLEX optimization software with mixed integer programming. ©2006 IEEE
Strategic bidding with regard to demand elasticity
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 30, Issue 6 , 2006 , Pages 691-700 ; 03601307 (ISSN) ; Ranjbar, A. M ; Shirani, A. R ; Sharif University of Technology
2006
Abstract
This paper presents a new method to analyze the bidding strategies of Generating Companies (GENCOs) with regard to demand elasticity. It is assumed that the available information of each GENCO about its opponents is incomplete and only the minimum and maximum generation levels of their opponents, as well as their fuel type, are known. In the proposed methodology, GENCOs prepare their strategic bids according to a Supply Function Equilibrium (SFE) model. GENCOs will change their bidding strategies until Nash equilibrium points are obtained. The general Algebraic Modeling System (GAMS) has been used to solve the maximization modules using the MINOS optimization software with non Linear...
Market power monitoring in electricity market by using market simulation
, Article 2006 IEEE Power India Conference, New Delhi, 10 April 2006 through 12 April 2006 ; Volume 2005 , 2005 , Pages 509-514 ; 0780395255 (ISBN); 9780780395251 (ISBN) ; Ranjbar, A. M ; Jafari, A ; Shirani, A. R ; Ranjbar, M ; Sharif University of Technology
2005
Abstract
This paper describes a new method for analyzing the bidding strategies of Generating Companies (GENCOs) in the Independent System Operator (ISO) point of view. ISO uses these results to detect the participants that have the potential for market power or actual exercise of market power. ISO models all GENCOs with perfect information. The proposed methodology uses the marginal cost of GENCOs as an initial point for bidding strategies of GENCOs and improves bidding strategies based on the objective function of GENCOs, the state of them in each hour of the day and with regard to ISO's market clearing problem. ISO tries to maximize the social welfare or minimize consumer's payments. The model...
Experimental investigation, modeling and optimization of membrane separation using artificial neural network and multi-objective optimization using genetic algorithm
, Article Chemical Engineering Research and Design ; Volume 91, Issue 5 , 2013 , Pages 883-903 ; 02638762 (ISSN) ; Shoushtari, N. A ; Mirza, B ; Salahi, A ; Sharif University of Technology
2013
Abstract
In this work, treatment of oily wastewaters with commercial polyacrylonitrile (PAN) ultrafiltration (UF) membranes was investigated. In order to do these experiments, the outlet wastewater of the API (American Petroleum Institute) unit of Tehran refinery, is used as the feed. The purpose of this paper was to predict the permeation flux and fouling resistance, by applying artificial neural networks (ANNs), and then to optimize the operating conditions in separation of oil from industrial oily wastewaters, including trans-membrane pressure (TMP), cross-flow velocity (CFV), feed temperature and pH, so that a maximum permeation flux accompanied by a minimum fouling resistance, was acquired by...
Producing water from saline streams using membrane distillation: Modeling and optimization using CFD and design expert
, Article International Journal of Energy Research ; Volume 44, Issue 11 , 2020 , Pages 8841-8853 ; Rezakazemi, M ; Younas, M ; Sharif University of Technology
John Wiley and Sons Ltd
2020
Abstract
Due to the increasing need for drinking water in the world, various membrane processes have been developing significantly over the past several years. The process of membrane distillation is one of the non-isothermal processes that cause steam to pass from the membrane due to the difference in temperature and the resulting difference in vapor pressure. Due to the lack of precision in the amount of flux and thermal efficiency in various operating conditions the membrane distillation process still needs development. This article attempted to examine the effects of flowrate, temperature, and module length on the performance of the membrane distillation process using computational fluid dynamics...
Using the group method for the synthesis of copper/ZrO2 nanocomposites to achieve high wear resistance by ball milling and spark plasma sintering
, Article Ceramics International ; Volume 48, Issue 12 , 2022 , Pages 17576-17588 ; 02728842 (ISSN) ; Hasani, A ; Amiri, Z ; Khayati, G. R ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The use of ZrO2 nanoparticles is common in the Cu matrix to manufacture Cu/ZrO2 nanocomposites. Many approaches and parameters produce Cu/ZrO2 nanocomposites with an appropriate wear rate and other properties. Hence, proposing an accurate and reliable model was imperative. The main goal of this paper is to find out the best models among the ant colony optimization (ACO), gene expression programming (GEP), artificial bee colony (ABC), and gray wolf optimization algorithm (GWOA) to predict the wear rate of/ZrO2 nanocomposites. To the best of our knowledge, this is the first research that predicts Cu/ZrO2 nanocomposites wear rate using group modeling. To develop models, 105 data were collected...
Optimizing shipment, ordering and pricing policies in a two-stage supply chain with price-sensitive demand
, Article Transportation Research Part E: Logistics and Transportation Review ; Volume 45, Issue 4 , 2009 , Pages 564-571 ; 13665545 (ISSN) ; Akbari Jokar, M. R ; Sharif University of Technology
Elsevier Ltd
2009
Abstract
In this paper we focus on a two-stage supply chain consisting of one vendor and one buyer. We develop an integrated production-inventory-marketing model to determine the relevant profit-maximizing decision variable values. The model proposed is based on the joint total profit of both the vendor and the buyer, and it finds out the optimal ordering, shipment and pricing policies. We are able to ascertain the optimal decision variable values employing an analytical solution procedure. The numerical evidence suggests that it is more beneficial for the buyer and the vendor to cooperate with each other when the demand is more price sensitive. © 2008 Elsevier Ltd. All rights reserved