Sharif Digital Repository

One of the satellite time-critical launch methods is air-launch, which is considered in this research thoroughly. The Large number of important parameters of this method makes the system highly complex. In such complex systems, usual methods of design and development will not be effective. Moreover, based on systemic approaches, interfaces between different elements of a complex system have significant effects on the performance of the whole system. One of the methods for analysis of such systems is “Design Structure Matrix” or DSM. This method is based on system engineering principles and has confirmed capabilities in analysis of highly coupled systems.
In this research, the air launch... 

The case of rapid small satellite aerial launch by mother airplane has various applications; such as space experiment, weather monitoring, and getting information from the earth monitoring during natural disasters. In this method, the satellite and the launch vehicle will be carried up by mother airplane to the definite height; then, the launch vehicle will be released and flied - to the insert of satellite into the desired orbit. Aerial launch system success depends on a set of complex elements and their interactions. In the present study, first of all, the element interactions will be investigated by system engineering approach based on operational scenarios; then, a new approach for... 

In this thesis, we study a queuing system with one server in which customers differ in both sensitivity to delay and willingness to pay. In this system, the server’s goal is to design a mechanism in order to maximize her revenue. It is worth to mention that nonlinear delay cost is implemented.Making use of the achievable region approach, we show that a well-designed menu of probabilistic admission control along with priority pricing contracts, may force customers to reveal their true valuations and at the same time induce customers that are more sensitive to delay to opt for higher priorities. Thus, the probabilistic admission control allows the server to identify the customers that are... 

The debate on the efficient way of altruism is a long-lasting topic. Economists attempted to model the nonprofit problems with game theory. Buchanan’s Samaritan Dilemma (1975) is one of the early instances, followed mainly by institutionalist researchers. However, no analytical model unifies the credible commitment problems. This thesis investigates two misallocation problems: the recipient’s motivation to deviate resources from the donor’s aims, and the information asymmetry that invokes affluent people to imposter eligible recipients. We probe a specific case representing a subsistence economy. One philanthropist faces agents with identical preferences but heterogeneous wealth, not... 

Natural gas liquefaction is an enabling technology which could make natural gas resources globally accessible. Nonetheless, the design and operation of LNG processes is highly complex, and is subject to multiple criteria including energetic, environmental and safety performance. Moreover, such processes must be flexible enough to operate under different feed conditions. The present research applies integrated process and product design framework to enhance simultaneously energy efficiency, environmental benignness, and inherent safety of a small-scale LNG process. The challenge is that the current group contribution methods applied for the estimation of the thermophysical properties, suffer... 

Chemical industries are associated with hazardous chemicals and extreme operating conditions. Unsafe events can incur dramatic costs in terms of the loss of life, financial penalties and damages to the environment. Therefore, design of industrial processes which can be operated safely over a wide range of operating conditions is vital. Nevertheless, operation of industrial processes is a strong function of their design. If the process is initially poorly designed, ensuring its safe operation, if not impossible, would require costly modifications at the operational phases. This observation is due to the fact that process design decisions (e.g. design of process equipment) often have a... 

In this thesis, the use of jet-engine for oil well fire fighting which is a latest in kind is described and analyzed. For this purpose, more familiarization with this system and some knowledge’s such as hydrodynamics characteristic of nominated area, traditional ways of fire fighting in region, different types of jet engines available type of offshore vessels, type of flame and their characteristic are required, which after studying and analyzing above fields in details, the use of turbojet motors and barge has been chosen for the case to obtain optimum specification os this turbojet motors and required dimensions of barge Some information about oil well shuch as, fluid output, speed rate... 

The purpose of this research is the conceptual design of an aerial robot that has the ability to reach different locations without changing its horizontal attitude. The main missions of the aerial robots are monitoring and delivery, in which none of them requires the robot to leave its horizontal attitude. The main task of the robot is to deliver the goods to the specified points. In order to do this, it must have an appropriate container for carrying the cargo, high safety to prevent damage to the cargo and individuals, the ability to carry out missions when one of the subsystems exits, and the appropriate flight speed for Deliver cargo to the customer as fast as possible. All of the... 

This paper proposes a novel real-time pricing tariff design aiming at reducing the operation cost of distribution system. A customer base-line load (CBL) is established for each participant. It let the customer to have less exposure with RTP volatile prices.The tariff charges the consumption above the CBL an hourly varying price. It credits the consumption below the CBL another hourly varying price.The proposed tariff provides the participant with more incentive and discount prices to encourage it to consume more efficient. The optimal prices are determined and announced a day in advance but can change in the next day with a short notice.The response of customers to the tariff prices is... 

The subject of this study is design of a linear quadratic Gaussian controller based on identification of dynamic behavior of unmanned model helicopter “Raptor” in its hover flight. To achieve this end, first, the helicopter linear transfer functions are identified with frequency response method by applying specific inputs to the model of Raptor in the X-Plane software and receiving system outputs via Simulink. Next, using the identified dynamic model of the helicopter, an optimum linear controller is designed for hover flight. As an optimum linear controller needs all the state variables, a Kalman filter is utilized to estimate them, using outputs of various sonsors such as GPS and gyro.... 

In this thesis, the goal is to design a predictive controller using orthogonal functions. In this way, we convert the minimization interval of the objective function into several subintervals, and in each interval, we consider the states and inputs of the system in terms of unknown coefficients of orthogonal functions, and we find the unknown coefficients according to the cost function and the dynamics of the system. According to the found coefficients, the control signal and modes are found in each interval. The length of the intervals, the number of foundations, the type of foundations and their effects on the system response and cost distribution are the questions that will be answered in... 

The present thesis introduces a new method to design non-fragile controllers. The idea of design is to set the centroid of the stability region as the tuning point of two-parameter controllers. This ideahas been motivated by the fact that the centroid of a convex region belongs to a set of pointsthat have farthest distance from its boundary. In case that stability region is not convex, a correction may be needed because the centroid of non-convex region may be very near to or out of its boundary. One modified version of design method when stability region is not convex, is to find maximum convex sub-area inside stability region and set its centroid as the tuning point of controller... 

Due to the prominence of low-order controllers in industry, this thesis intends to improve the common design algorithms in this field. In this regard, the main challenge is that this problem is NP-hard due to the non-convex rank constraint which appears in the formulation. The existing algorithms mostly solve this problem by obtaining a convex sub-space for this constraint and using output feedback convex optimization methods.Two of common algorithms are non-iterative. These methods two main steps; first to obtain the full-order Lyapunov matrices related to the controller, and then, to fix the null-space of the matrices which have rank constraint. One of the advantages of the algorithm... 

The design and implementation of the hybrid control method for a three-pole active magnetic bearing (AMB) is proposed in this paper. The system is inherently nonlinear and conventional nonlinear controllers are a little complicated while the proposed hybrid controller has a piecewise linear form, i.e., linear in each sub-region. A state-feedback hybrid controller is designed in this study and the unmeasurable states are estimated by an observer. The gains of the hybrid controller are obtained by the LQR method in each sub-region. To evaluate the performance, the designed controller is implemented on an experimental setup. The experimental results show that the proposed method can efficiently... 

Electrical energy customer and load growth on the one hand and the problems of allocation of land for the development of the power networks on the other hand, make the tendency to use less space in the electrical industries. One of the solutions used in power distribution networks, especially in crowded areas is compact substation which requires less space than ordinary substations and also the prefabricated types of this substation can be used in the distribution system. In a compact distribution substation, all components must be designed with a minimum size. Therefore, the insulation system of the compact substation should be designed based on these requirements.
In the distribution... 

Functional design of coating system for the primary mirror of the Iranian National Observatory (INO) is done. This telescope has a 3.4 m primary mirror in diameter, made of Zerodur from Schott. Although similar coating systems are in use since years ago, this is the first attempt to design a system for such a large surface case in Iran. Systematic approach led us first to clarify and identifying the design requirements. Lower limit of 80% for reflectance on all wavelength range from 325-1000 nm, thickness of 100 nm with un-uniformity of 5 nm, adhesion enough to pass the selotape test and surface roughness of less than 8 nm. Study of the available methods for coating and selection of the best... 

In recent years, energy harvesting from ambient sources in order to use for low-powered electronics has been considered by many researchers. Wind energy, solar energy, water energy, mechanical energy from vibrations, etc are common sources of ambient energy. In this thesis, optimization of energy harvesting from ambient vibration using magnetic shape memory alloy is presented. To this end, a clamped-clamped beam coupled with MSMA units is considered. A shock load is applied to a proof mass which is attached to the middle of the beam. As a result of beam vibration a longitudinal strain is produced in the MSMA. This strain changes magnetic flux inside the coil connected to MSMA and as a... 

The purpose of this study is developing the design means of a high pressure centrifugal compressor impeller for aviational applications i.e. turboshaft engines. The logic and constraints of designing a high pressure centrifugal impeller for a turboshaft engine is different from those of low pressure aerial or high speed industrial ones. This kind of impeller is deployed in a number of advanced generation of aero engines. In this study, the centrifugal impeller design tools are developed using two design methods. Then, the results are compared, validated and corrected with an existing high pressure impeller data. A number of impellers with pressure ratios ranging from 6 to 11 are designed and... 

In this project, tomato processing waste has been considered as a raw material for bio-refinery applications. Some products from tomato wastes that are usable, economical and environmentally friendly have chosen after lots of studying on researches in regards of producing valuable materials from tomato waste. I’ve used “Superpro designer” software for economical evaluation and determining the possibility of this practice for industrial applications. Beside the tomato paste factory, the process includes one unit of Lycopene production. In addition to Lycopene production, it is possible to produce fertilizer from residues and using them as livestock food or producing energy for the output... 

The objective of this project is to design and control a single-stage three-phase unity power factor telecom rectifier. Following a comprehensive literature review on single-stage three-phase AC-DC converters, high-frequency isolated three-switch buck rectifier is selected. In this thesis, the analysis, design, and control of isolated buck converter is based on previously developed methods for classic three-switch buck rectifier. Three-phase isolated buck+boost rectifier is introduced by integrating a boost converter to the isolated three-phase three-switch buck rectifier and modified control structure. The proposed structure is simple and has good performance for heavily unbalanced mains...