Sharif Digital Repository

This study presents a developed successive boundary element method to determine the sloshing natural frequencies, mode shapes and equivalent mechanical models for multi baffled 2D and axisymmetric containers with arbitrary geometries. The developed fluid model is based on the Laplace equation and Green's theorem. The governing equations of fluid dynamic and free surface boundary condition are also applied to proposed model. A zoning method is presented to model arbitrary arrangement of baffles in multi baffled axisymmetric tanks. The influence of each zone on neighboring zones is applied by introducing interface influence matrix which correlates the velocity potential of interfaces to their... 

In this research, the location-inventory problem is developed in order to design a distribution center considering customers behavior. We consider two groups of customers who have different behavior on purchase. The customers may order the product via internet and receive it at their location or go to the nearest store and buy the product at the store center. We model the problem as a multi-objective programming model. The objectives are maximizing the profit as well as maximizing the market share. The model locates the distribution centers (DC) and allocates the customers to DCs. Two heuristic algorithms developed to solve the model: non- dominated Sorting Genetic Algorithm (NSGA-II) and... 

Robots have been widely used for various applications, especially during the last decades. Robots are made of several parts, in which, "Hand" is one of the most important of those. Hands are designed according to their applications and are not necessarily like human ones. Development of humanoid robots, however, brings a special place to human-like hands. In this research, a force-isotropic underactuated finger with two phalanxes and one actuator is designed, considering design limitations and through static analysis. Tendon, cam and mechanical lock (ratchet gear) are among the main components which have been considered in the finger design. Then, a model was fabricated and tested in order... 

Rotating machinery are found in most industrial units, that are highly susceptible to transverse cross sectional cracks due to fatigue. The vibration pattern of a rotor system reflects the mechanical parameter changes in the system. These vibrations can be used for identifying the cracks and appropriate actions can be taken to prevent more damage to the system. The dynamic behavior of cracked rotor is a subject of considerable current interest. Several researchers have developed models of cracked rotor systems. Therefore, In this thesis, the influence of the presence of transverse cracks in a simple Jeffcott rotor is analyzed. In first, on the basis of fracture mechanics, the direct and... 

Systems that are electrostatically actuated have found a vast role in MEMS application. This technology is used in optical systems, sensors, micro switches, and deformable mirrors. Raising the use of these systems in fields that needs better performance highlighted the need to accurate study of dynamics and control of electrostatic actuated systems in micro scale. This work is dedicated to design of an estimation and control system for a micro-beam that is actuated by electrostatic. After a comprehensive survey on pervious works that are done on dynamic, applications, fabrication and control of these systems dynamic of the system is fully derived. The environmental factors like fringing... 

According to high nominal pressure and controllable flow, variable displacement axial piston pumps are used widely in hydraulic industry. However, there still exist many problems and limitations in the areas of design, controllers and performance. To solve the problems without wasting time and money in making prototypes, an accurate dynamic model of the pump is required which predicts pump behavior under various control signals and loads. The lack of simple and practical methods of measuring describing parameters of pump dynamics, makes investigation and verification of such a model very challenging. In this thesis, literature review is presented in a wide range. After investigating of... 

Assortment planning considers the problem of product classification in order to maximize the profit by considering related constraints. Integrating the assortment planning with inventory management plays an essential role in retail optimization. The importance of integrating these problems is related to customer behavior in substituting the products in case of shortage. The customer checks the availability of products in order of his/her priorities and buys a product if available otherwise leaving the store without purchase if he/she cannot find a product according to his/her preferences. Customer preferences are modeled through the definition of consumer types, where a type is a ranking of... 

In this thesis, pull-in of nano/micromirrors under effects of capillary, Casimir and van der Waals (vdW) forces is investigated based on two models. In the first model, only rotation of torsional beams of mirror is considered. In the second model, effect of bending of the torsional beams is also considered. The static behavior of the mirror under capillary, Casimir and vdW loading are also studied using these models. Results show that neglecting bending effect, can lead to considerable overestimation in predicting the pull-in limits of the nano/micromirrors under these forces.Results reveal that the static behavior of the nano/micromirrors under these forces highly depends on the... 

In this study hybrid classification models by combining genetic algorithm and classifiers such as neural network and decision tree are presented and efficiency of these models is tested on 5 different databases against other proposed models in this area. This comparison shows that the model obtained by combining genetic algorithm and neural network obtains better results than other models. Afterwards this model is used as a decision support system in diagnosis heart disease and in addition to determining the parameters of neural network such as the number of hidden layers and the number of neurons in each layer, efficient features in diagnosis heart disease are also determined. Among the... 

Synchronization means to control the response system to follow the drive system. It first began in 1990 in a paper by Pecora and after that it is used in many applications like secure communication. Another application for synchronization which is introduced here is identification of chaotic systems. According to the research done, this application hasn’t been in the literature as it is known to us. Synchronization papers usually devide into two parts. In one of them the parameters of the systems are unknown, so adaptive laws are used to estimate the parameters. In the other part, the parameters are taken known. It is not mentioned in the first group that the estimation would converge to the... 

In this thesis, the problem of the hotel revenue management with the customer choice behaiver has been studied . In this model , each customer has a preference order among the set of products. He purchased or booked his products according to his ordered list of preferences. Because the high number of hotel products are assumed, each customer can only choices different fare classes and the list of the preference customers is made up of different fare classes. Two different approaches have been used to solve this problem . The first approach is The linear programming model in which α percent of the capacity is allocated to business customers and the remaining capacity to leisuer customers... 

Undoubtedly today for all scholars and intellectuals have been established in various countries to obtain the knowledge and abilities would create amassing wealth for their scientific, The twenty-first century, therefore, important to develop methods of science are two-fold.
However, in today's world, science has been faced with many problems that it solves, many scientists and philosophers of science of the mind is engaged, Despite the many advances in medical problems, for example, that there are still many problems in the treatment of diseases, And this, according to many scientists in different fields of scientific expert has been approved.
But given the history of Muslim... 

Since Formation control have potentail applications in civil and military industries, decenterlized control of formation control is studied in this work using consensus algorithm. A specific robot quadrotor with 3D motion is used in this work. Quadrotor is an underactuated vehicle. First, we derivate twice from dynamical equations of linear positions. Hence, we can obtain appropriate form using linearization of output equations for design a consensus control algorithm. It is needed to design fourth order control algorithm for control of multiagent systems, beacause of twice derivation. Two methods that have been used for formation control in many works are potential function method and... 

In the aftermath of mass-casualty events, main resources may be overwhelmed by the sudden jump in demand. To ration these resources with considering the patients priority for help, mean triage. For prioritizing the patient for help, the limitation of resources should be considered. These resources can be different. This thesis at the first step investigates how the priority assignment can be done in a clearing system and what the potential benefits would be when there are same resources in the system. At the next step, the difference between resources is considered. So in this thesis, the problem of priority assignment of patients in an emergency system is modeled and analyzed at first with... 

The observed response of medium rise buildings during sever earthquakes worldwide has indicated that RC buildings with shear walls behave considerably better than other buildings. The conviction that shear walls are inherently brittle still prevails amongst engineers, and therefore, they usually prefer to choose moment resisting RC frames without shear walls. In this study, a number of RC frames, with and without shear walls are designed in accordance with the seismic codes, and are then subjected to an assemble of severe earthquakes. The results of timehistory nonlinear analyses of these models are then used to investigate the effect of the presence of shear walls within the framework of... 

In this thesis, the effect of elastodynamic behaviour of an interceptor on it’s trajectory in space and accuracy in desired positioning and situation is investigated. The governing equations of motion are derived and linearized by using the basic equations of motion in the body frame axes and the mode summation method for elastic deformations. In order to control the interceptor, the closed-loop control on the yaw and pitch angles, is considered. The governing equations of motion are solved to determine the time response to investigate the structural effects on the stability, position and situation of interceptor. Finally, the effect of elasticity and vibrations on the interceptor’s... 

In the present work, dynamic behavior of submerged slender bodies under external hydrodynamic forces with internal sloshing tanks is studied. The main application of this thesis is in submarines. For this purpose slender body theory is used for hydrodyanamics of body and unsteady hydrodynamics is used for the vehicle control fins. In submarines there are some water tanks that control the buoyancy, so that sloshing can be importatnt. An equivalent mechanical model is developed for simulating the dynamics of sloshing tanks. Assuming that a submarine is a slender body, elastic deformation of submarine body can affect dynamics of the whole system. Elastic behavior of the main body is simulated... 

In this project, the landing process is simulated by using of multi-body dynamics commercial software. Various factors, including landing situations, aircraft structures and climate are used in this simulation. The purpose of this project is to determine the forces exerted on the aircraft landing gears in landing process in various landing conditions. For this purpose, the ADAMS multi-body dynamics software is used. At first, different scenarios based on FAR-25, including level landing, tail-down landing, crab landing are simulated. Results of dynamic simulation software with landing load factor obtained from the analytical solution are compared. Then for the level landing, different... 

The paper presents the results nonlinear analysis of steel base plates subjected to different combinations of axial and bending forces. The bending forces range from small moments representing small eccentricities to large moments from seismic actions. The results of analyses proved to be in good agreement with experiments. The parameters investigated in this study are as follows: distribution of strain and stresses in the concrete foundation and the steel plate, the strains and stresses in the tensile anchorage bolts, the location of neutral curve under the base plate, the centre of compressional reaction forces in concrete, the flextural rigidity of the base plate connection, and the axial... 

In this research dynamic modeling of a 3-DOF (degree of freedom) compliant parallel mechanism with flexible intermediate links has been investigated. Unlike conventional rigid mechanisms that gain their mobility from movable joints, the compliant mechanisms transmit or transform through elastic deformation of flexible members (flexible connector and joint), displacement, force, or energy from input into output. Eliminating clearance, friction, wear and demand of lubrication in compliant mechanisms, and having monolithic structure provides high-precision motion with micro/nanometer level resolution for them. Therefore compliant mechanisms play a significant role in modern technologies such as...