Sharif Digital Repository

A cooperative aerial system to defense a Ground Station (GS), against an Incoming aerial Targets (IT) is presented. GS is surrounded by given terrains and a group of homogenous Unmanned Aerial Vehicles (UAVs) are employed using a novel online guidance algorithm in a decentralized manner. The proposed algorithm includes loiter, midcourse and terminal phases. During loiter; UAVs follow an optimal circular path. IT is supposed to approach GS along an optimal low altitude trajectory with respect to the terrains. UAVs are informed the initial position and velocity of IT and they are unaware of IT trajectory. Each UAV decides on whether to engage with IT or not, and shares its decision with other... 

Non-uniform laminated beams are being used in many engineering applications as primary elements. Helicopter blades, wind turbine blades and robot arms are examples of applications of these structures, in which the high stiffness-to-weight ratio and the non-uniform geometry are of high importance. Changing the thickness in laminated structures is a big challenge in fabrication view as different tapering configurations may significantly alter the stiffness of the structure. Thus, increasing the stiffness and dynamics characteristics of tapered beams with simple configuration is of high importance. The present work aims to investigate the effect of adding nano particles in resin during the... 

For optimum designing of dry friction clutch, we should taking into account a lot of parameters, in order to the clutch have good efficiency in torque transmission and power train. These parameters include: the type of friction plate and the mechanical properties, Clutch geometry, diaphragm spring and its ability to make pressure. In this project, the goal is the analysis of effect of different parameters in clutch's temperature distribution and effect of these issues in torque transmission. In next step, the clutch's temperature distribution analyzed by changing the friction plate (ceramic), pressure applied and relative round in order to gain optimum properties of clutch. These works done... 

According to the wide range of applications and numerous implementations, wireless networks are considered as a prominent means of providing data services, and have attracted the attention of many researches in recent years. Performance enhancement of these networks can be very beneficial to industry and wireless data service providers. Manipulation of relays, have been always considered as a proper means for improvement of network performance measures throughput and outage probability.In order to design relay networks efficiently, one should address two following problems: 1- determining transmission policy, and 2- relay location. In this research work, having in mind the optimality of... 

In present study we are going to introduce a biomechanical model of lumbar spine with using finite element method and use it for evaluating the behavior of spine under different loading conditions.Spine as the main part of muskloskeletal system of human body is tolerating various forces during daily activities.So it's important to know about different approaches for studing the loading conditions wich is using for evaluating the behavior of lumbar implants. In other words in order to obtain correct outputs we need to simulate the real condition in the experiments. We can use biomechanical models in order to comparison the different approaches  

The sudden increase in population growth rate in major cities and the recent changes in life style (consumerism) have resulted in a massive load of municipal solid waste. Managing this huge amount of waste imposes a heavy burden on municipalities’ shoulders. There are several options to Manage Solid waste, among them incineration and landfill are widely use in Managing municipal solid waste. Considering the fact that these two options are potentially hazardous to environment, high moisture content of municipal solid waste added, composting has become more trendy approach in last decades.Although composting is more environmentally friendly, it still needs the waste to be collected from all... 

This study is a modeling for “building’s energy consumption” as well as selecting an optimum composition of technologies to meet a building’s needs, with an approach of reducing energy and facility costs . In modeling the energy stream to evaluate heating comfort and to calculate building’s heating load, the interaction between these two phenomena is assumed to be en block. The unique and en block study requires surveying mass and energy streams from all particles of a building, which are not traceable in simple static methods. This study assumes a building with following requests: heating load, cooling load,air conditioning and heat water. An optimum selection of facilities and... 

The price that customers pay for electric energy is determined by cost of generation, transmission and distribution parts. In Practice all customer have main concern about reliability of electric energy, because of it’s major effect on different aspect of life. Although customers are interested to have fully reliable service, but power companies are aware that it is impossible to achieve this goal from technical and economical aspect. The utilities and customer benefits can be achieved through minimization of the total investment cost of network, while improving the reliability and quality of electric service. This also requires to minimize the customers service interruption time. To meet... 

In the building, can be used variaty of Heating, Ventilating and Air conditioning systems. Among the items that affect to select the hvac system can be pointed to building thermal demand and system energy consumpsion. simulation of this systems is one of the ways that can compare hvac systems in the building. according to Iran needs for preparation of software for optimization of energy carriers consumption in building proportional with existing matrials and equipment in the country, in this research has been tried methodology and modeling of hvac systems in the way developed that producted software is capable simply and practical for engineers be operational in a residential unit. In realy... 

Portfolio is a collection of different stocks for investment. The investors' objectives in portfolio formation are to get the highest return against exposure to the lowest risk. Portfolio Optimization Problem is one of the most complicated problems in investment and finance. It may be simply explained as follows: Let's imagine a set of N stocks for selection. We would like to see what percentage of the total amount of investment should be dedicated to each stock to maximize portfolio's total return and minimize its total risk.
Portfolio Optimization Problem is a NP-Hard problem and generally there exists no polynomial-time deterministic algorithm to find a precise solution to such a... 

Each year about 23 thousand people will be death in the road accidents in our country. According to the Legal Medicine Organization of Iran, about 24 percent of pedestrian fatalities in road accidents are the result of a collision with a car and because of that studying the different parameters that reduce pedestrian injury became an important issue to study. There are different techniques such as simulating crash tests on cadavers, experiments on pedestrian dummy and numerical simulation. The purpose of this project is simulating the car-pedestrian crash with numerical software called Madymo. Then optimize of the various parameters such as the height of the front bumper height, hood,... 

Project in brief: reconfiguring the network according to application which has been run on the network is one of the ways to improve using resources in the network-on-chip. There is a hierarchical cluster based NOC. In this network, nodes are going to partition into clusters. Every cluster’s node can have its own configuration and the configuration of inside of each cluster is unchangeable however the relationship between clusters is configurable. This ability is made by some switches which are located between clusters and they can change the way that clusters are related. The number of nodes which is inside the cluster are cluster size and the number of switches between two adjacent... 

Process plants such as refineries and petrochemical plants are complex facilities consisting of equipment, piping systems, instruments, electrical systems, computers, and control systems. Process units design is mostly based on designer`s experience and design general criteria and standards. Using mathematical methods to optimize the design may have an effective role in cost reduction and it would give the designer some general view in case that the exact design is not applicable.
Optimization of Process units is described in this study. This optimization includes the exact location of each equipment, nozzle, pipe rack and also pipe route layouts. Mixed integer linear programming (MILP)... 

In this thesis, two-level optimal control of uncertain and non-uncertain large-scale systems is presented. In the proposed two-level approach, using a decomposition/coordination framework, the large-scale system is first decomposed into several interactive subsystems, at the first-level, where a smaller optimization problem is solved at each subsystem. At the second-level, a substitution type prediction method, as a coordination strategy, is used to predict the interaction between subsystems. The coordinator mainly evaluates the next update for the coordination parameters and continues to exchange information with the first-level, so that the overall optimum solution is obtained. It is shown... 

Turbojet engine combustors play a key role to convert energy with very high rates. To reach this goal, the combustor must satisfy many conflicting requirements. Complexity of the flow field inside the combustormakes the 2D or 3D analysis very difficult. In this thesis, a quasi one-dimensional software is developed applying empirical and analytical 1D relations. Using data for a mini-turbojet engine, the range of some important design parameters is extracted and then a new combustor is designed using both velocity and pressure loss methods. Different disigns are investigated and are compared by employing an extended version of the simulation software. Due to the unacceptable performance... 

Using biomechanical models is one of the most effective ways to analyze and assessment of spinal loads in occupational and daily activities. In spite of many advances in the spine modeling, personal factors especially body weight are ignored in most studies. Epidemiological studies show that high body weight is a very strong risk factor of low back pain (LBP) and disc degeneration. There are only few studies that evaluate the relationship between spinal loads and body weight. The goal of this study is analyzing the effect of body weight on spinal load. A detailed musculoskeletal model of lumbar spine with 18 degree of freedom and 76 muscles was developed. This model consists of two parts... 

Automotive brake pad is one of the most widely used composites. Commonly, more than 10 components are applied to make these materials and due to the large number of components and interactions between them, choice, explaination of the behavior and optimization of brake friction materials are some industry's challenges. Until now, some methods have been presented to design and optimization of these materials, but due to different complexities, there is lack of practical method that could be used for explaining the tribological behavior, engineering calculation and optimization of brake friction materials. Today, formulation of the current brake pads in the industry has mainly come from trial... 

This thesis presents a general method for real-time adaptation of wireless receivers according to the prevailing reception conditions. In order to maintain the desired signal quality at the minimum possible power dissipation, the method performs an optimal trade-off between noise, linearity, and power consumption in the building blocks of the receiver. This is achieved by continuously monitoring the signal-to-noise plus interference ratio (SNIR) and accordingly tuning the adaptation parameters embedded in the receiver design. A prototype DVBH receiver chip, implemented in a standard 0.18-µm CMOS process, is used as the test vehicle. By properly trading noise with linearity in the receiver,... 

Cognitive Radio (CR) technology enables dynamic spectrum access (DSA) to overcome the problems of unlicensed bands which is becoming overcrowded. However, providing an acceptable quality of service (QoS) for cognitive users requiresmore sophisticated approachesdut to the existence of primary users (PU) with their high priority over licensed bands. Additionally, reducing interference with primary users so that they can communicate without interruption is of extreme importance. In order to meet cognitive user’s quality of service as much as possible and reduce interference with PUs, a new class-based multipath on-demand routing protocol for cognitive radio networks (CMORC) is proposed. CMORC... 

Aerodynamic shape optimization has been always of great importance in aerospace design. Recent advancements in computational algorithms and hardware, has made it feasible to have advanced optimization as a standard part of desing procedure. Here we have promoted aerodynamic optimization in three different applications, i. e., wing-body configuration, hydro propellers, and air propellers. First we have reviewed fluidic theoretical aspects, and have selected appropriate physical models or existing softwares. Accuracy of physical analysis or software is validated. Then different optimization algorithms are reviewed, and schemes used in this thesis are described and the softwares are validated. ...