Sharif Digital Repository

In this project Sharif Gas Turbine laboratory turbojet engine, and the turboshaft engine which is designed based on the turbojet gas generator are statically and dynamically modeled and required functions for turboshaft control are extracted. In static modeling a repetitive process is applied to reach static operation points. Static operation line and static characteristics of turbojet engine are extracted and compared to relevant sources. In dynamic modeling of turbojet engine a lumped volume is allocated to each component of engine and gas dynamic equations are solved in this volume along with individual performance map of engine components to acquire output characteristics in each time... 

In this project, polymer nanocomposites containing graphene oxide were prepared and used for adsorption of several cationic and anionic dyes. In most cases, these nanocomposites were prepared as three-dimentional polymer networks which contain graphene oxide. Nanocomposites with direct grafting of polymer chains onto the surface of graphene oxide were also prepared. Graphene oxide is an oxidized carbonaceous material with unique properties. This material has high surface area, good mechanical strength and various functional groups. Polymeric compounds with different functional groups, structures and properties can be prepared and used. By preparing composites of graphene oxide and polymers,... 

Soil liquefaction occurring in loose saturated sand deposits during seismic loadings is one of the most destructive earthquake-induced phenomena in the field of earthquake geotechnical engineering. Catastrophic destructions due to this phenomenon that have been observed in the earthquakes such as Kobe (1995), Chi-Chi (1999), etc. has led to extensive studies in this field. In case of soil slopes prone to liquefaction hazard, detailed analysis of this phenomenon requires considering soil-related factors (e.g. shear strength, relative density, permeability, slope geometry) on the one hand, and earthquake-related characteristics (e.g. amplitude, frequency, duration) on the other. Numerical... 

The energy consumed by lighting, heating, ventilating, and air conditioning (LHVAC) systems have been increasing over the last decades. Thus, improving the efficiency of LHVAC systems has gained the attention of industry and academia. This concern has posed challenges for controlling and optimizing LHVAC systems. The traditional methods, such as on/off and PID approaches, usually involve conditions and parameters that may not hold in practice since LHVAC systems are complex, nonlinear, and dynamic. Also, controllers are one of the important components of a method for its efficiency. This research focuses on controlling LHVAC systems. Fuzzy logic controllers one of the best controller for... 

Portfolio optimization is an most important field of study, affecting companies’ non-operating income, so companies try to achieve this beneficiary by incorporating it in market transactions. In this thesis, we propose some methods extending the Markowitz theory. We used the lagrangian method and other appropriate operations research techniques such as convex optimization in order to handle optimization process. Using these methods, we established portfolio optimization model for different corporation, i.e., banking industries and others, with different interest rate exposure for short and long conditions of risk free assets. We describe three risk criteria as possible alternatives to... 

Cooperative coexistence of two kinds of users with different priorities in random access wireless networks has been studied in this thesis. Source burstiness, a phenomenon in data communication networks, allows using silence periods of primary users (PUs) to have a better spectrum utilization. In this respect, new users, known as secondary users (SUs), are considered to exploit the resources opportunistically. In usual spectrum sharing systems, SUs have to act in a way to be transparent for the PUs. Therefore, they are allowed to access the common spectrum band only when PUs are silent. However, seeking such opportunities needs sensing capability of secondary nodes.In this thesis, sensing... 

There are a lot of methods for the settlement of the reserve power market which can ultimately lead to a pattern of consumption and generation for each of the participants of the power market. After this step, however, justified and logical methods should be utilized for paying the reserving costs to the participants as in a long-term it can optimize the economic conditions of the market which can result in getting more realistic bidding from the participants. The current methods used for paying the reserving costs are mostly locational marginal prices and pay-as bid approach. By the same token, for receiving the reserving costs from the customers, some consider the desired reliability level... 

Sparse representation and compressed sensing have been widely used in various fields, one of the most popular of which is ISAR imaging. Inverse Synthetic Aperture Radar (ISAR) provides an electromagnetic image of the target, which is mainly used to identify and classify targets. In some applications, recognizing targets from a 2D image can be difficult and error-prone. One idea to deal with this problem is 3D ISAR imaging. The most widely used method of ISAR imaging is direct method based on Fourier transform. This method requires the measurement of radar data with high measurement density in 3 directions, which increases the data collection time and volume, which is the main problem of... 

The primary objective of this research is probabilistic quantification of the fatigue life of tension-leg platforms (TLP) using reliability methods. The need for such methods stems from the significant uncertainty in the loads exerted on offshore structures. The scope of this paper is limited to the study of fatigue in TLP tendons. For this purpose, nonlinear force time history response of the TLP tendon under random wave loads is computed and the damage due to fatigue is estimated in accordance with the Palmgren-Miners rule. Assuming a Rayleigh distribution for stress variation and eight different sea states, the ultimate fatigue damage is computed by accumulating the damage over all... 

Ambient Intelligence is a new paradigm in information technology that creates environments able to detect and respond to users needs, actions, behaviors and feelings. In the presence of interaction conflicts, user trust plays an important role in accepting Ambient Intelligence environments for living, working, etc. Our main hypothesis is that higher conflict density results in a greater loss of trust in mixed-initiative Ambient Intelligence environments. In this thesis, we propose a comprehensive research method for measuring trust in Ambient Intelligence environments using both crowdsourcing and university surveys. We conduct both web-based experiments and physical experiments to gather... 

One of the challenges in the field of Ambient Intelligence is empowering end-user to determine the level of system interference in the control of the environment. One approach to answer to this challenge is using End-user Development to determine the rate of system intelligence as well as develop the behavior of the system by the user himself. In this way, the user introduces his intended behavior to the system so that the system operates in accordance with it.In this research, we have provided end-user development for an intelligent environment considering children as the end-user; for this purpose, we have designed a game-based user interface, allowing children to be involved in the... 

Developing of electric instruments with high performance needs high capacity heat transfer equipments. Pulsating heat pipes have better performance compared with normal heat pipes and can be used for cooling electronic instruments in near future. Also, one specific kind of heat pipes, which is called rotating pulsating heat pipe, can be used in cooling the turbine blades and every rotating device. Rotating pulsating heat pipe is a cooling device in which the pipes can rotate around the axis perpendicular to the plane of pipes. In this research one rotating heat pipe was built and the effects of heat input, filling ratio, working fluid and rotational acceleration were examined experimentally,... 

There are a wide variety of radar systems that one of them is MIMO Radars. After a spark in communication in 1998 that developed MIMO communication, recently there has been a great attention towards MIMO radar systems. MIMO radars divided into co-located and widely separated branch. In this thesis, the spatial diversity and multiplexing gain and the tradeoff between them in MIMO communication and MIMO radar systems investigated. Diversity and multiplexing gains in communication defined analytically, so diversity and multiplexing gain presented as detection probability improvement and throughput or capacity improvement respectively. Also tradeoff between these two gains investigated... 

Ambient intelligence is a new paradigm in human computer interaction in which smart actor interact with the surrounding environment and be helped in to reach their goals. One of the main principles in smart environments is the interaction between user and the system. Better interaction leads to a better user satisfaction. In explicit interaction, context plays an important role in interaction quality. One of the main parameter in interaction is the environment complexity. Environment complexity itself consists of other factor such as size of the room, number of devices, density of devices, size of the devices and etc. In this study, we have investigate the effect of two factor, environment... 

Nowadays, concrete is considered as one of the most important and useful engineering construction materials. Different concrete with diverse characteristics are used in various designs every day. One of the main considered parameters in concrete usage is its compressive strength. So far, many additives are used to increase the compressive strength of concrete most important of which are Nano-Silica and Micro-Silica. In addition, some of concrete characteristics such as water-to-cement ratio have significant effects on the concrete strength. Many experiments and investigations are conducted so far to study the effects of each of mentioned factors separately on the concrete strength. However... 

Statistical studies indicate the fact that in Iran, like many other developing countries, a significant percentage of buildings are made of traditional materials and most of them are adobe buildings especially in rural areas. Furthermore, geological data indicates that Iran is located in alps-Himalayas seismic zone and exposed by destructive earthquakes and adobe buildings suffer the most damages comparing with other type of the structures. According to these explanations, this research deals with adobe buildings behavior and provides solutions for reinforcing them and improving the seismic response of these buildings. These studies include numerical modeling with finite elements methods by... 

The aim of this thesis is the requirements analysis, design, proof-of-concept implementation and user evaluation of a novel user interface that is specifcally developed to support interaction with ambient intelligence systems. The focus of the user interface is rather on interacting with ambient intelligence, a meta system that comes into existence as the result of the coherent behavior and collective intelligence of interconnected smart devices and systems of a domain such as meeting rooms or smart homes.To design the user interface, we conducted an empirical user and task analysis and elaborated requirements, defning the scope of human interaction with ambient intelligence. The captured...