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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

A Novel Dithering Algorithm to Reduce Electro Magnetic Interference in Voltage Source Inverters

Namburi, Krishna Mohan Pavan Kumar 14 August 2012 (has links)
No description available.
82

Investigation of Registration Methods for High Resolution SAR-EO Imagery

Hansson, Niclas January 2022 (has links)
With advancements in space technology, remote sensing applications, and computer vision, significant improvements in the data describing our planet are seen today. Researchers want to gather different kinds of data and perform data fusion techniques between them to increase our understanding of the world. Two such data types are Electro-Optical images and Synthetic Aperture Radar images. For data fusion, the images need to be accurately aligned. Researchers have investigated methods for robustly and accurately registering these images for many years. However, recent advancements in imaging systems have made the problem more complex than ever. Currently, the imaging satellites that capture information around the globe have achieved a resolution of less than a meter per pixel. There is an increase in signal complexity for high-resolution SAR images due to how the imaging system operates. Interference between waves gives rise to speckled noise and geometric distortions, making the images very difficult to interpret. This directly affects the image registration accuracy. In this thesis, the complexity of the problem regarding registration between SAR and EO data was described, and methods for registering the images were investigated. The methods were feature- and area-based. The feature-based method used a KAZE filter and SURF descriptor. The method found many key points but few correct correspondences. The area-based methods used FFT and MI, respectively. FFT was deemed best for higher quality images, whereas MI better dealt with the non-linear intensity difference. More complex techniques, such as dense neural networks, were excluded. No method achieved satisfying results on the entire data set, but the area-based methods accomplished complementary results. A conclusion was drawn that the distortions in the SAR images are too significant to register accurately using only CV algorithms. Since the area-based methods achieved good results on images excluding significant distortions, future work should focus on solving the geometrical errors and increasing the registration accuracy
83

Data Acquisition, Analysis, and Modeling of Rotordynamic Systems

Mullen, Michael P 01 June 2020 (has links) (PDF)
Data acquisition systems for rotordynamic analysis and machine vibration were explored for the purpose of replacing the obsolete Bently Nevada ADRE 208 and ADRE for Windows system. These included the development of Matlab based custom data acquisition systems and a user interface. A model of an anisotropic rotor response undergoing transient speed was developed for the rapid prototyping and testing of data acquisition systems. Several methods for the measurement of amplitudes and phase in both the time domain and frequency domain were developed and compared. An alternate data acquisition method which is more inline with industry practices was created for the purpose of spectral analysis. Additionally, an optimized data acquisition strategy was developed for implementation within the Matlab app which included batch processing, state-based acquisition, and differentiated vector and waveform acquisition rates. A Bently Nevada 2300/20 vibration monitor was configured for use in the lab but found unsuitable for replacing the ADRE 208. Ultimately a Bently Nevada ADAPT 3701/44 Vibration Monitor was configured and found to be an adequate replacement for the ADRE 208 system for use in the Cal Poly Vibrations Lab.
84

Analyzing the efficacy of the FFT in Image Denoising and DigitalWatermarking

Fagerström, Emil January 2023 (has links)
The FFT has been a staple in the field of mathematics and computer science for almost 60 years. And yet, it still endures as an efficient algorithm in a multitude of fields. However, as significant technical advances has been made since its inception the demand on methods constantly get higher and higher, and the FFT is seldom enough to solve the problems of this day and age on its own. So how does the FFT perform on its own with today’s standards? This thesis aims to use the FFT to create two algorithms, an Image Denoising algorithm and a Digital Watermarking algorithm respectively, and analyse the efficacy of the algorithms with today’s standards. The results showed that the FFT on its own competently tackles problems well, however with increased demands on the algorithms, the limitations of the FFT became apparent. This underscores the prevalent trend of integrating the FFT with other specializedmethods, ensuring its continued relevance in an era of continuously advancing technologicaldemands.
85

Radar Signal Characteristic Extraction with FFT-Based Techniques

Pennington, Jason R. 25 May 2011 (has links)
No description available.
86

A Fast Poisson Solver with Periodic Boundary Conditions for GPU Clusters in Various Configurations

Rattermann, Dale N. 27 October 2014 (has links)
No description available.
87

GPS Coarse Acquisition Using the MonoBit FFT Algorithm in a Broadband Receiver

Flynn, John 11 August 2008 (has links)
No description available.
88

Hypercube machine implementation of a 2-D FFT algorithm for object recognition

Datari, Srinivasa R. January 1989 (has links)
No description available.
89

Novel design of multiplier-less FFT processors

Shepherd, Simon J., Noras, James M., Zhou, Yuan January 2007 (has links)
No / This paper presents a novel and hardware-efficient architecture for power-of-two FFT processors. The proposed design is based on the phase-amplitude splitting technique which converts a DFT to cyclic convolutions and additions. The cyclic convolutions are implemented with a filter-like structure and the additions are computed with several stages of butterfly processing units. The proposed architecture requires no multiplier, and comparisons with other designs show it can save up to 39% total equivalent gates for an 8-bit 16-point FPGA-based FFT processor.
90

Spectral analysis for rod formation dynamics

Stewart, Shannon Thomas 17 December 2008 (has links)
This thesis deals with the production of a continuous rod of non-uniform properties which is formed by wrapping fibers with a thin membrane. This rod is driven axially and cut into segments. Measurements of pressure, temperature, axial force, axial velocity, horizontal and vertical displacements were taken of the rod during normal operating conditions at various speeds. The time signal for these tests were converted to the frequency domain through the use of a Fast Fourier Transform (FFT). The data was then examined to determine the inputs into the rod from various components of the rod producing machine. The results of the experiments show that the machine has inputs in several location along the production line. It also shows that changing components of the machine based on their frequency response may be beneficial in minimizing the number of stoppages in the production of the rod. This investigation into the dynamics of rod production shows that there is a potential for significant gains in production by altering certain components of the production machines. This report also offers a future test procedure that should help to better explain the rod’s motion and thus may lead to more efficient production. / Master of Science

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