Papers by Keyword: Fourier Transform

Abstract: There are various vendors of FFT libraries, but there is no software available for it automatic benchmarking on all available devices. In this article an application that allows easy measure the performance and precision of various FFT libraries on the available GPUs and CPUs is presented. This application has been used to find out the fastest FFT library for NVIDIA GTX TESLA and NVIDIA GTX TITAN. The obtained results shown that the best implementation is provided by cuFFT library developed by NVIDIA.

Abstract: Double exposure speckle is proposed to calibrate eddy current sensor in micro-displacement measurement for its simplicity, robustness and high resolution. The specklegram is taken as the vector of the displacement. The actual displacement of an object is calculated according to the speckle displacement on the spatial term, which is worked out according to the fringe spacing on the spectrum surface. A calibration system is proposed with proper speckle size and imaging magnification. Experiments showed that the accuracy of displacement measurement is 0.196um with an optical magnification 65.8. The calibration curve of the eddy current sensor is consistent with the result by a nanopositioning system.

Abstract: In this paper, overlaid cement concrete pavement with crack is considered based on fracture mechanics. Cement concrete pavement is reduced to an elastic plate on Winkler foundation. Fourier integral transform, residue theorem and Lobatto-Chebyshev integration formula are used to obtain the analytical solutions of this problem. To analyze the effect of overlay for the old pavement, stress intensity factors ofItype crack and II type crack are calculated respectively for various overlay thicknesses, elastic moduli of the overlay. The stress intensity factors of the crack tips in the pavement with 10cm thickness overlay are reduced heavily. However, stress intensity factors are less affected by elastic modulus of overlay material.

Abstract: In view of the high precision requirements of the more complex stamping parts of the springback law, this paper put forward a rebound closed loop control system model based on the improved Fourier transform. First of all, starting from the product model, it use the method finite element analysis and the forming process parameter optimization for the initial mold design, and then to measure the mould and stamping products and assess the springback error. Finally, eliminating the springback error through two iterative loops to complete the final mold fixed compensation. Experiments show that the system can complete the mould shape correction effectively by using the model and realize the springback compensation of complex stamping parts.

Abstract: Intelligent predictive maintenance (IPdM) is a maintenance strategy that makes maintenance decisions automatically and dynamically based on Artificial Intelligence and Data mining techniques through condition monitoring of machines, equipment and production processes. IPdM system consists of the following main modules: sensor and data acquisition, signal and data processing, feature extractions, maintenance decision-making, key performance indicators, maintenance scheduling optimization and feedback control and compensation. Among them, the most important part of IPdM is maintenance decision-making, which includes diagnostics and prognostics. This paper proposes a framework of intelligent faults diagnosis and prognosis system (IFDaPS) and discuss some key technologies for implement IPdM policy in manufacturing and industries. A case study focus on the vibration signals collected from the sensors mounted on a pressure blower for critical components monitoring. We decompose the pre-processed signals into several signals using Wavelet Packet Decomposition (WPD), and then the signals are transformed to frequency domain using Fast Fourier Transform (FFT). The features extracted from frequency domain are used to train Artificial Neural Network (ANN). Trained ANN model is able to identify the fault of the components and predict its Remaining Useful Life (RUL). The case study demonstrates how to implement the proposed framework and intelligent technologies for IPdM and the result indicates its higher efficiency and effectiveness comparing to traditional methods.

Abstract: In order to install the wave power facilities in ocean and coastal area, it is very important to determine the properties of wave data. Discrete wavelet packet transform was applied in this study and was used as a tool to find out the basic properties of waves around Namae coast. Important features of hydrodynamic pressure such as frequency and magnitude were investigated in different observation time. Also the idea of measuring the noise rate was introduced and applied to both stationary and non-stationary time spans for the comparison. These methods would be useful to check the feasibility of wave energy extraction in various types of coasts.

Abstract: Digital holography is a comparatively new observation method for micron-sized particles. It is based on numerical reconstruction of recorded interference fringe. Calculation processes for reconstruction are both time- and memory-intensive. The aim of this study was to develop a faster, more efficient algorithm for digital hologram reconstruction. To this purpose Central Processing Unit (CPU) and Graphics Processing Unit (GPU) programming were implemented. For the problem solving the algorithms’ run-time for both configurations was measured. The results showed that the algorithm using a GPU board is faster and more suitable for reconstruction processes. Thus, it makes possible the accomplishment of real-time analysis.

Abstract: Fourier transform is an important tool in a number of scientific fields. Its advantages, disadvantages and subtleties have been examined many times by dozens of mathematicians, physicists and engineers. In this contribution we try to summarize important aspects of this transform and discuss variety of its uses in contemporary science with emphasis on demonstrating connections to dynamic interactions in the vehicle-roadway system.

Abstract: When it comes to the digitized image, it is a process of converting analog image of continuous tone which has been sampled and quantized into digital image. The application of digital technology in modern art has become one of the hot spot in this field. First of all, this paper undertakes the digital image process of image. According to the filtering properties of the Dirac function, this paper analyzes the two-dimensional sampling principle of digital image. Based on this, the relationship between image spectrum before sampling and after sampling is compared and analyzed according to the related properties of Fourier transform. And then it is obtained that it is concluded that the ideal low-pass filter can make the sample undistorted. By further analyzing the error of the sampling value quantification processing, the rebuilt best quantitative values of image can be obtained. Thats to say, the reconstruction of digital image is the inverse process of image sampling. To a certain extent, it provides scientific theoretical basis for the integration of digital image in modern art design.

Abstract: Based on the comparative analysis of the fast Fourier transform (FFT), the short-time Fourier transform (STFT), the wavelet transform (WT) and other power quality detection algorithms, this paper puts forward to a new power quality detection algorithm which combines the Fourier transform with the wavelet transform. The transient as well as the steady state signals are separated on the basis that the wavelet transform is sensitive to the singular signals. The presented algorithm detects a variety of harmonic parameters of the gird after the separation of steady state signals is finished by fast Fourier transform. A new power quality detection system is then designed based on the core chip of S3C2440A, and the algorithm which is ARM-9 based is transplanted into the embedded Linux operating system to carry out the experiments. Analysis of the experimental data shows the detection algorithm is reliable by Fourier transform and wavelet transform.