جستجوی مقالات مرتبط با کلیدواژه « تابع تبدیل » در نشریات گروه « فنی و مهندسی »

The purpose of this paper is to simulate the vibrations caused by the aerodynamic force of the wind blowing. Disturbances of air currents over the cable cause the oscillations of the cable with certain amplitude. In this paper, the Dryden turbulence model is used to model wind-induced aerodynamic force. The equations of motion of the cable connected to the electromagnetic damper is obtained by using the Hamilton principle and then they are discretized to a set of linear ordinary differential equations by adopting the Galerkin method. In the following, the transfer functions of the first vibration mode of the cable are obtained and the bode diagrams for these transfer functions are plotted using MATLAB software. Then the effects of random gust parameters, such as length scale, turbulence intensity and wind speed on the frequency response of the cable are investigated. The results show that increasing length scale and wind speed decrease the resonant frequency of the system.

In this paper, a mathematical model and experimental evaluation of flow control valve with pressure compensator is presented. Proper compatibility of the experimental results with the results of solving the mathematical equations, under steady state conditions, confirmed the validity of the mathematical relationships governing the flow control valve with the pressure compensator. Investigations showed that by increasing the cross-sectional area of the flow in the adjustable orifice, the displacement of the spool increased. Also, changing the oil pressure difference on both sides of the valve has no effect on the oil flow through it. The relationship between the inlet and outlet quantities of flow control valves with pressure compensator was determined by Gcsx and Gcsp transfer functions. Investigations showed that under all conditions the flow control valve with a pressure compensator is stable. The stability of two Gcsx and Gcsp transfer functions, with increasing oil pressure difference decreased and increased, respectively. Also, increasing the displacement of the adjustable orifice removable member, reduces the stability of the Gcsp transfer function and improves the stability of the Gcsx transfer function.

Due to the increasing variety of medical images and the need for physicians to perform these images for a more accurate diagnosis, the need for automated systems that make the diagnosis process faster and easier is felt more than ever. These algorithms allow the identification, measurement and comparison of images very accurately by matching two homosexual or heterosexual images. In this paper, in order to automatically stabilize the magnetic resonance images of the brain, first, efficient spatial features are extracted through active contours. The point points are selected from the center of gravity of the closed spaces in the image, and after evaluating the point points and selecting the corresponding points, using the appropriate geometric transformation, it stabilizes the two brain images optimally.

Transformer winding mechanical fault detection by Ultra Wide Band (UWB) Sensors has been recently proposed. In this paper, modal analysis technique has been used to detect and estimate radial deformation and axial displacement in transformer winding. In this technique, using the UWB wave propagation channel modeling by transfer function and knowing that mechanical changes affect the channel parameters, the features have been extracted for the fault diagnosis. By choosing the best method of estimating the transfer function, the zeroes and poles in different sound and defective mode has been determined. For diagnosing and determining the approximate amount of the faults, the amounts of Zeroes and Poles of the Transfer Function have been compared in different modes. The measurement results have been shown that the proposed method can be successful in the detection of the fault but it cannot determine the amount of the faults accurately. According to the capabilities of the proposed method, it can be used in combination with the previously introduced Radar Imaging Method.

In this paper, frequency response analysis (FRA) of transformer based on the detailed model of the transformer windings, is investigated. The determination of the detailed model parameters, which can be considered as a large scale model, is a complex task. To overcome this problem, a heuristic method is presented in this paper. This method is applied to a large scale detailed model with nineteen sections.The state equation model is used, to extract the transfer function of the large scale detail model of the transformer. In this paper, all parameters of the model are assumed to be frequency dependent. Also, a new improved detailed model is presented. It is shown that this model can represent the transient behavior of the transformer winding better than the well-known detailed model. In the laboratory, all new ideas presented in this paper, are applied to a 20/0.4-kV and 1600-kVA transformer. The comparison of simulation and measurement results show the privilege of the improved detailed model in comparison with the conventional ones.

The purpose of this article is modal analysis of ionic polymer metal composite beams, then briefing the system to the unique parameters to help in up modeling of the actuator. In this paper at first using of Mathematical analysis and Closed form transfer function of cantilever beam dynamic response to the forces of different inputs (intensive and continuous) is calculated and for different types of systems resonance and anti-resonance points in frequency analysis are found, then with using modal analysis of system the entire response is briefed in the basic mode and parameters of un-damped natural frequency and damping coefficient in this mode is to introduced for the system, after the cantilever composite beam considered as an operator with the input voltage, displacement and produces a force on the free end, By observing the behavior of the system, analyzed responses to the inputs.

In this paper, free and forced vibration analysis of functionally graded material cylinders was carried out by mesh-free and finite element method. In this analysis, MLS shape functions are used for approximation of displacement field in the weak form of motion equation and essential boundary conditions are imposed by transformation method. Resulted set of differential equations are solved using central difference approximation. Mechanical properties of cylinders were assumed to be variable in the radial direction as a function of volume fraction. Effects of geometrical dimensions of the cylinders, exponent of material volume fraction and the effect of loading type were investigated by the proposed model and FEM. Results obtained by this analysis were compared with the analytical solutions and the results of finite element analysis, and a very good agreement was seen between them.