Sharif Digital Repository

In line with advances in science and technology in the areas of robotics, artificial intelligence, computer and control, unmanned vehicles are being more utilized and focused. On the other hand, development and further advances of these vehicles is highly dependent on the level of their autonomy. Motion planning is one of the most important issues in this regard. Due to high levels of autonomy required for unmanned air vehicles (UAV), the subject of motion planning is of valuable interest in aerospace applications. The goal of the motion planning problem, that is the subject of this research, is to extract an optimal trajectory for the UAV from an initial location toward its target point... 

Most of the recent hydro-system researches lent themselves to integrated modeling of interactions between agricultural water demand and hydro-system operation for better agricultural water demand management. Large share of water consumption by agriculture sector and general acceptance of integrated water supply and demand management by water sector decision makers highlighted this approach in hydro-systems analysis. This approach in modeling helps to achieve a better management strategy for agricultural water demand and supply with the least reduction in agri-sector economic indices, while supplying industry, domestic and environmental target demands. However, agriculture, industry and... 

Electric vehicles (EVs) will be used rampantly in future transportation system. Although the uncontrolled charging of these EVs will be threatening for the stability and sustainability of the grid, a well-suited energy trading policy may provide a number of beneficial services to the grid as well as preserving the sustainability of the system along with heightening the performance of operation. In this paper, by taking advantage of block rate tariff, a wholesale pricing policy is introduced. A multi-objective approach is utilized to address the cost reduction and load levelling services, concurrently, in order to guarantee the profits of the both the grid and EVs. Due to the high... 

Location-allocation problem is known as one of the classical problems in industrial engineering. The goals of these problems are finding optimal location of facilities and assigning these facilities to service demands from a given set of point. Location-allocation decisions are widespread through all organization in the world concerning private and public businesses. Therefore, in this study, a practical mathematical model is formulated and solved.In this paper we present a new approach for a budgeted constraint capacitated location-allocation problem integrated with cellular layout approach containing cell formation and group scheduling. Main decisions are composed of formation of... 

Recent studies show that the code-compliant structures have faced a lot of damages in earthquakes, and their performance could improve. The structure should have the least initial cost in this approach, which observes all of the code's limits regardless of the structure's life cycle cost. In recent years, value-based design has been considered as an alternative for code-based design procedures. In this method, some other parameters are considered as well as the initial cost of the structure, including risk, resiliency, reliability, and sustainability. In this paper, the structures' total cost is studied by Fema P-58, while it is equipped with viscous dampers. The structures are 4, 8, and 12... 

In this project a complete simulator for a two-winding, 25cm air gap Maglev system by considering the pratical constaritns, position and velocity observer and the current sensor dynamics was derived. In order to control the ball in any desired position a twisting sliding mode controller was designed as the basic controller in the rest of project. The designed controller can not transfer the ball in far trajectory. In first step we modify that to reach a better performance by changing the value of current, passing through the coils in steady state. In the second step, the far trajectories are divided to a finite number of sub-trajectory such that the ball can pass these sub-trajectory by... 

Nowadays, radiation therapy is one of the most common methods for the cancer treatment. Intensity Modulated Radiation Therapy(IMRT) is a novel technique of radiation therapy that aims to delivere sufficient dose to cancerous tissues while sparing healthy organs. There are various uncertainties in radiation therapy problems, including uncertainty about device setup, device errors, interfraction and intrafraction motions. One of the most important uncertainties is the movement of the tumor during the treatment process(intrafraction motion), as this displacement may cause the cancer tissue to not receive sufficient dose and also to damage the healthy tissue due to a violation of their dose... 

Service composition is an important problem in the cloud manufacturing paradigm in which, after receiving a customer request, combination of cloud services are determined for accomplishment of customer needs. Actually, customer need is decomposed to some distinct tasks such that each one is done by a company or a group of them. In this way, virtual and cloud-based production line can be developed based on requirements of customers. The ultimate goal of service composition is optimum assignment of tasks to factories while some objective functions (e.g. minimization of cost and time) and constraints (e.g. minimum reliability and availability) are considered. In this study, integer programming... 

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... 

In recent decades, rapid growth in the utilization of energy resources has led to using a system of combined power, heating and cooling due to their high efficiency. Losses of electrical power transmission and distribution networks are also another reason to emphasize using the combined production systems. Today, the use of small scale combined production systems at the same time, competitive with electricity generated from renewable energy technologies have also emerged. The present study was undertaken to answer questions on the topic of disrict heating and cooling system design with power that can be occur. For this purpose, first the governing mathematical equations are expressed and... 

This thesis is concerned with an optimal trade-off between communication overhead and the number and size of neighborhoods in a distributed optimal control technique for large-scale systems that is based on the Jacobi iteration and two-layer architecture for communication. Although this method efficiently reduces computational overhead, continuous and proper data transfer between subsystems that are very often far from each other, is required to achieve an acceptable performance. However, limited transmission bandwidth and short communication range result in significant communication overhead. This causes significant time latency between measurement and applied calculated control actions,... 

For the simulation of microbial systems, constraint-based models have been proposed. The most famous constraint-based model is the flux balance analysis, in which to apply extra-molecular effects into the system, the dynamism of the problem is also introduced to generate the dynamic flux balance analysis. In this thesis, the bee colony optimization algorithm is used as an optimization engine. To increase the simulation accuracy and obtain more accurate solutions, this method was further developed and tested with thirteen benchmark functions. Better results were obtained compared to other proposed algorithms. Then the proposed algorithm was developed with four methods for constrained... 

In recent years, liquid resin injection processes for aviation applications have been considered an alternative to conventional autoclave-based processes. At present, these processes have challenges that have been denied industry trust due to their inability to be objectively reproducible. In the last decade, some software has been developed to simulate the vacuum injection process, but this software does not have enough capability to predict the injection network, and an operator with sufficient empirical knowledge must use this software. In recent years, researchers have used this softwares to simulate the process, but so far no software has been developed that can offer injection... 

The actual flow stream through compressor is 3D and fluctuated because of complicated geometry, fluid viscosity and high velocity. Therefore, more accurate analysis of this kind of flow, it is better to use 3D model. Nowadays the flow modeling software are able to model and analysis flow regime using numerical methods in three dimensions. Using these software allow us to find the ways which can reduce the energy losses to improve compressor efficiency.In current work, based on 3D numerical analysis, the flow regime in a centrifugal compressor is investigated and also the sensitivity of this analysis with mesh sizing is explored. The k-e type RNG model is used for modeling turbulent behavior... 

Groundwater in coastal aquifers is one of the essential resources of freshwater in coastal regions, where are heavily populated or industrialized areas, and have critical ecosystems.The management of these resources is a priority to preserve groundwater from serious natural and human-induced threats such as salinization caused by seawater intrusion. The combined simulation-optimization techniques can be used for this purpose in determining optimal planning and management strategies. The implementation of such techniques for complex real-world and large -scale problems has major difficulties in terms of both computational efficiency (solution quality and required computational time) and... 

Agriculture is one the most water consuming sections in the world and roughly 60% of water demand is dedicated for this purpose. A seawater greenhouse manages to combine fan and pad greenhouse with humidification-dehumidification desalination in order to achieve water production next to agriculture products using moister in air which was used for cooling. The most important aspect of a seawater greenhouse is the amount of produced water. Many research on the condenser type and materials have been conducted in order to achieve a better performance, suggesting the utilization of a low temperature water source for the condenser. In this research, using a thermodynamic correlations to model the... 

Cross docking is a novel docking method which importance in supply chain management has been underlined in recent decades. Two main operations of regular docking centers, including storage and picking up are eliminated in cross docking facilities in order to decrease inventory holding costs, shorten lead times and at the same time increase service level. Although inbound and outbound flow at each cross dock are determined by the flow of shipments through the network, overwhelming majority of papers in this field have addressed each of local and network-wide cross docking problems mutually in isolation. That being so, the problem dealt with in this research, is to how determining the flow of... 

Due to well mechanical properties and high resistance to environmental conditions, metal pipes are used to transport oil and gas products, water and sewage, as well as hydraulic systems in aircraft or aerospace systems. Therefore, maintenance of oil and gas transmission lines in energy-related industries and pressurized tanks in the aviation industry has always been a concern of engineers. Due to the problems of old methods for repairing damaged pipelines or aerial structures, it seems necessary to provide new, safe and cheap methods for repairing them. Various engineering standards for pipelines and their repairs have been presented so far which have analytical solutions to determine the... 

In this thesis, unconstrained convex quadratic optimization problems subject to parameter perturbations are considered. A robustification approach is proposed and analyzed which reduces the sensitivity of the optimal function value with respect to the parameter. Since reducing the sensitivity and maintaining a small objective value are competing goals, strategies for balancing these two objectives are discussed. Numerical examples illustrate the approach  

Thus far, there has been a great attraction toward the optimal flight path planning problem. Terrain following/avoidance (TF/TA) flight is one of the most significant applications of this issue. To prevent from detection by the radars, fighter aircrafts, cruise missiles and helicopters often have to fly as close as possible to the surface during the operations. Such types of maneuvers are much more demanding and effortful than to be designed and implemented by human. The optimal TF/TA guidance system design comprises three phases: optimal path planning, closed-loop control system design for trajectory tracking and sensor blending to match the onboard and measured terrain data. So far, the...