Sharif Digital Repository

Study of the structural flexibility of large-scale wind turbine components on aeroelastic performance is important under the existence of critical atmospheric conditions. Prediction and control the critical deformations, identifying maximum local deformation and modeling the forces involved, are required. Aeroelasticity analysis is a suitable method for studying the coupling effects of wind turbine aerodynamics, dynamics and structures. This research has been done by modeling wind turbine components including blades, hub, nacelle and tower, taking into account aerodynamic couplings, dynamics and structures. Considering the large scale of reference wind turbine, nonlinear equations have added... 

The circular flexible cylindrical liquid tanks are usually made of steel or aluminum and in majority of cases are built on grade due to its economic advantages. The most important part of a safe design of storage tanks is the accurate estimation of the seismically induced lateral forces that should be transformed to its base through the tank shell and its support . seismic behavior of the liquid storage tank is quite different from regular buildings industrial structures due to its nonlinear behavior caused by complex distribution of hydrodynamic pressure, buckling of its wall, etc.. moreover, the effect of rocking motion caused by under laying soft soil, on its response parameter could be... 

Multi-period Value-at-Risk (VaR) forecasting is important for risk management. Financial institutions especially commercial banks according to Basel Committee regulations for capital adequacy in “Internal Approach”, should forecast their VaR for multi-period horizons (longer than one day). The most conventional approach for forecasting multi-period VaR is scaling one-day forecasted VaR that is called “square root of time rule”; therefore most works in this area have been focused on forecasting one-day VaR. In this study, we review performance of a wide range of different methods in forecasting multi-period VaR. The results of our study show that historical simulation performs weakly in... 

Our ultimate goal in this thesis is to design a chaotic receiver for detecting small targets in sea clutter. Sea clutter at low grazing angle has a spiky behavior and in this thesis we desire to model this irregular behavior in the chaos theory frame work. Using a trend similar to statistical detection theory, we will obtain the suboptimal chaotic receiver and investigate the receiver noise effect on the optimality or sub optimality of the detector. Chaotic detector can be used in the coherent and non coherent mode. Although the coherent detector has a superior performance, the efficiency of the non coherent detector is acceptable as well. We will investigate the efficiency of the chaotic... 

One of the most important alternative technologies in the field of security monitoring is millimeter-wave imaging technology, which is a good alternative both for performance and cost-effectiveness. Conventional security monitoring techniques use optical images or metal detectors to control people in crowded, sensitive places, but with the help of electromagnetic waves, these technologies can be obtained. This way, metal and non-metallic objects hidden inside clothing, bags or shoes can also be detected that are not identifiable by conventional security-control methods. This thesis examines the implementation of an improved algorithm for automatic detection of objects in millimeter-wave... 

The integration of radar and communication functionalities into a unified Joint Radar-Communication (JRC) system offers enhanced spectral efficiency and reduced hardware complexity. Recognized as a key enabler for next-generation wireless networks, JRC systems require a careful balance between radar and communication demands, where waveform design plays a pivotal role in achieving this equilibrium. Although waveform design has been extensively studied separately in radar and communication domains, the requirements of modern networks necessitate a unified approach that simultaneously addresses the needs of both systems. This thesis advances waveform design methodologies for JRC systems,... 

The issue of solid and fluid interaction in horizontal axis wind turbines with diameter of more than 120 meters is one of the most important researching subjects of this type of turbines. This issues needs quick and exact solutions because of the high computational cost of fluid and structural domains.In this research a quick method with acceptable accuracy has been suggested which is based on computational fluid dynamic to examine the aeroelastic behavior of rotor and wind turbine tower. The actuator disc method in two domains of axisymmetric and three-dimensional has been used to compute aerodynamic forces. For this purpose a code has been written in C++ to set down virtual momentum on... 

Fog computing environment consists of several devices which distribute across an arbitrary topology. Each of these devices is capable of carrying out a designated computation simultaneously with other devices. One of the common ways of describing a computation is through the usage of workflows. Workflow is a flexible and formal way of modeling tasks and their requirements for execution. A workflow is essentially a DAG. Therefore, it can model the data dependency between tasks quite accurately. The complex structure of a workflow in conjunction with the homogenous nature of devices in a fog environment makes it difficult to find a resource management algorithm to minimize execution time, used... 

This project focuses on the design of fuel drop tanks for airplanes that add minimal drag and positive lift to the flying object. This will obviously effect the stability and dynamic performance of the airplane. To reduce adverse dynamic effects the tank was divided to several segment with a special emptying sequence. The add-on tank has to have no interference with the object existing systems and require minimum structural changes in the object. Several designs were proposed and the one gaining highest marks was selected. The flow field and the dynamic behavior of combined vehicle and drop tanks were studied using FE simulations. The result shows that adding a drop tank with optimized... 

Cancer can be defined as a stochastic phenomenon. Thus, the tumor growth can be defined as a stochastic process. A Cancer tumor can be analyzed by its geometric shape. Furthermore, computing fractal dimension of shapes is a useful technique to analyze chaosity and complexity of shapes. This approach can be used to compare results from laboratory with simulated results of a mathematical model. A stochastic model of tumor growth will be presented. And some geometrical properties will be analyzed through computer simulation of the model  

The effects of combined task demands on the way muscles are recruited to balance external loads during posture and movement is of great importance in quantitative analysis of upper arm function. Pain and disability of shoulder joint is becoming more important as population spends more often interacting with computers in seated position and carrying repetitive tasks using upper extremities. Shoulder joint that is more dependent on the muscles for its normal function than other joints such as hip due to its small articular surface and large range motion has been used here to study its coordination during isometric exertions. Since, the numbers of tasks that could be performed are enormous. In... 

In the present study, the axisymmetric liquid gas/air diffusion flame in the presence of fuel concentration oscillations and velocity perturbations has been investigated experimentally. Several industrial combustions take a place by diffusion mechanism which necessitate scientists to make far better understanding of diffusion flames. In order to study diffusion flames, the instrument with two separated lines of fuel and air has been developed. Nitrogen is used for fuel dilution oscillatory with pulse of 1, 2, and 4 Hz frequencies. The pulse duration effects on flame structure are also studied. The flame shape has been captured by high speed camera and the results are processed by image... 

This research evaluates the effect of external corrosion geometry and bending moment on the burst pressure of pipes. In recent decades, the use of natural resources of offshore oil and gas has increased, as a result, the use of offshore pipelines for transferring products has grown dramatically. At the same time, numerous accidents and explosions in offshore pipelines and its economic and environmental consequences indicates the importance of ensuring safe operation. Pipeline Integrity Management has been developed to ensure safe and efficient operation of pipelines. Integrity management includes planning, inspection, evaluation and repair. This cycle is checked continuously. The importance... 

Burner scaling criteria have been studied and the most appropriate one has been selected to scale down a large industrial burner. The sub-scaled non-premixed swirl-stabilized burner is manufactured to ensure that the available experimental setup and equipment are sufficient and practical for characterizing the burner. The aim of the research is to assist the future design optimization with the identifications which have been done. The constant residence time method is selected in this project and it is shown that this is the proper criteria for non-premixed and swirl-stabilized burners. For better identification, stability maps of the flame are extracted with the experimental methodology for... 

The purpose of this study was to create a three-cationic electro phosphate coating of zinc-nickel-manganese by cathodic method and to investigate the effect of operating variables on the properties of zinc-nickel-manganese tri-cationic electro phosphate coating. Hence, the effects of variables such as coating acidity, coating thickness, coating temperature, coating time and concentration of manganese were studied in the bath on the properties such as coating morphology, corrosion resistance, coating thickness. Coating morphology was characterized by scanning electron microscopy and corrosion resistance by polarization test. The pH values of 1.4, 1.8, 2 and 2.2 were selected, and the results... 

Airport saturation is one of the important issues which have always been of the specialists’ concern. One of the major applications of this subject is at the airport approach problems. While using current conventional approach procedures have many disadvantages regarding high fuel consumption and subsequent much environmental and noise pollution, the CDA concept which is one of the modern topics introduced in consequence of free flight theory, has less such disadvantages compared to conventional approach. Subject of this study is to investigate whether Procedural approach or CDA saturates an aiport sooner if the traffic flow increases. In this dissertation, using BADA database, CDA... 

Connections have a crucial role in the behavior of every structure. Amongst various types of connections used in steel structures are those used to connect the columns to the foundations, namely Base Plates. As other types of connections, base plates control the behavior of the structure in various respects including affecting the effective length of columns. The main task of any base plate is to distribute the forces of the column on the foundation in such a manner that the stresses in concrete are below their allowable values. Different configurations, with or without various attachments, are used for designing the base plates hence achieving various types of behavior with various levels... 

Networked business is a kind of businesses, relatively new and very complex, worthy of more analysis and study. From all types of networked businesses, “Platform based” ones are subject of this study. To solve “the problem of networked business”, in this study we try to develop a conceptual framework, using different disciplines especially:
- Business model studies
- Network science and social network studies
- Economic and strategic studies of platforms
Besides some new business concepts defined and theorized in this study, reader will find the conceptual architecture, applicable to the general of the business  

Nowadays, Resource Capacity Management (RCM) is one of the main challenges for industries which have a limited capacity to meet the demands. Revenue Management (RM) is a technique that controls the supply, improves the quality of Capacity Management and maximizes the revenue. Supplying the products and services to different groups of customers is a decision making problem.While the classic RM techniques take into account only the expected revenue, preferences of decision makers strongly affect the results. In this study, utility theory has been proposed because the healthcare industries are usually nonprofitable and they are not highly focused on the revenue gained by their products and...