Master of Science

thesisDue to the complex failure modes associated with composites, a structural health monitoring system capable of accurately locating the source of strength-reducing events is desirable in order to reduce inspection time and time out of service. Various active and passive inspection techniques exist but most require large footprints and extensive cabling to monitor full scale structures. This work derives various location techniques by coupling modal acoustic emissions with phased array techniques to detect and accurately locate the source of strength-reducing events such as impacts. Phased array techniques provide a method to more accurately track phase points for determining arrival times used to back-calculate the source, as well as providing a method that can incorporate anisotropic wave speeds. To increase accuracy by neglecting local to global material changes, the local velocity profile per component was found and built into the derived location algorithms. The location algorithms were then tested on two full scale composite structures based on strength and stiffness critical design considerations. It was found that with two arrays, each with dimensions of 1 inches in width and 8 inches in length and consisting of four sensors each, events could be accurately located over a 65 ft2 region on the stiffness critical structure with an average error of 10 inches and over a 100 ft2 region on the strength critical structure with an average error of 9 inches

Discrete Wavelet Transforms

The discrete wavelet transform (DWT) algorithms have a firm position in processing of signals in several areas of research and industry. As DWT provides both octave-scale frequency and spatial timing of the analyzed signal, it is constantly used to solve and treat more and more advanced problems. The present book: Discrete Wavelet Transforms: Algorithms and Applications reviews the recent progress in discrete wavelet transform algorithms and applications. The book covers a wide range of methods (e.g. lifting, shift invariance, multi-scale analysis) for constructing DWTs. The book chapters are organized into four major parts. Part I describes the progress in hardware implementations of the DWT algorithms. Applications include multitone modulation for ADSL and equalization techniques, a scalable architecture for FPGA-implementation, lifting based algorithm for VLSI implementation, comparison between DWT and FFT based OFDM and modified SPIHT codec. Part II addresses image processing algorithms such as multiresolution approach for edge detection, low bit rate image compression, low complexity implementation of CQF wavelets and compression of multi-component images. Part III focuses watermaking DWT algorithms. Finally, Part IV describes shift invariant DWTs, DC lossless property, DWT based analysis and estimation of colored noise and an application of the wavelet Galerkin method. The chapters of the present book consist of both tutorial and highly advanced material. Therefore, the book is intended to be a reference text for graduate students and researchers to obtain state-of-the-art knowledge on specific applications

Progress towards Bell-type polarization experiment with thermal neutrons

Experimental tests of Bell-type inequalities distinguishing between quantum mechanics and local realistic theories remain of considerable interest if performed on massive particles, for which no conclusive result has yet been obtained. Only two-particle experiments may specifically test the concept of spatial nonlocality in quantum theory, whereas single-particle experiments may generally test the concept of quantum noncontextuality. Here we have performed the first Bell-type experiment with a beam of thermal-neutron pairs in the singlet state of spin, as originally suggested by J. S. Bell. These measurements confirm the quantum-theoretical predictions, in agreement with the results of the well-known polarization experiments carried out on optical photons years ago

Divergence Model for Measurement of Goos-Hanchen Shift

In this effort a new measurement technique for the lateral Goos-Hanchen shift is developed, analyzed, and demonstrated. The new technique uses classical image formation methods fused with modern detection and analysis methods to achieve higher levels of sensitivity than obtained with prior practice. Central to the effort is a new mathematical model of the dispersion seen at a step shadow when the Goos-Hanchen effect occurs near critical angle for total internal reflection. Image processing techniques are applied to measure the intensity distribution transfer function of a new divergence model of the Goos-Hanchen phenomena providing verification of the model. This effort includes mathematical modeling techniques, analytical derivations of governing equations, numerical verification of models and sensitivities, optical design of apparatus, image processin

Caracterización de haces ópticos vía tomografía en el espacio de fases

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Óptica, leída el 12-09-2014Depto. de ÓpticaFac. de Ciencias FísicasTRUEunpu

Characteristics of confined square jets in the vicinity of a free surface.

The results of an experimental investigation of a turbulent jet flow issuing from a square nozzle in the vicinity of a free surface are presented. Experiments were conducted using a two-dimensional laser Doppler anemometer and a particle image velocimeter. The focus of this study was the near region of the jet (X/B \u3c 30). Here, B refers to the nozzle width and X is the distance from the nozzle exit. LDA measurements were conducted at eight stations downstream of the nozzle exit along the centerline of the jet. Four tailwater depths were used in this study. Additional measurements were also conducted to identify axis switching and to this end measurements were obtained at various transverse locations. PIV measurements were conducted in the near jet region (X/B \u3c 3) corresponding to a tailwater depth of 2.5B. A good comprehension of the fluid dynamics of a square jet expanding in the vicinity of the free surface is achieved. Higher order moments were calculated to provide information on the coherent structures and study the role of velocity fluctuations. Two local peaks on either side of the jet centerline is observed. The difference in magnitudes of the peaks indicate differences in the prevailing entrainment characteristics on the top and bottom portions of the jet. Through the quadrant analysis, sweep and ejection type events were observed. To better understand these events, four kinds of eddies are classified for simplicity and their behavior is discussed.* (Abstract shortened by UMI.) *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .S26. Source: Masters Abstracts International, Volume: 44-03, page: 1441. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005

Quasi-Dirac neutrinos and solar neutrino data

We present an analysis of the solar neutrino data in the context of a quasi-Dirac neutrino model in which the lepton mixing matrix is given at tree level by the tribimaximal matrix. When radiative corrections are taken into account, new effects in neutrino oscillations, as $\nu_e \to \nu_s$, appear. This oscillation is constrained by the solar neutrino data. In our analysis, we have found an allowed region for our two free parameters $\epsilon$ and $m_1$. The radiative correction, $\epsilon$, can vary approximately from $5\times 10^{-9}$ to $10^{-6}$ and the calculated fourth mass eigenstate, $m_4$, 0.01 eV to 0.2 eV at 2$\sigma$ level. These results are very similar to the ones presented in the literature.Comment: 24 pages, 7 figures and 2 tables. Results and conclusion unchanged. Version published in EPJC. Figures improve

Effect of the Metal Transfer Mode on the Symmetry of Bead Geometry in WAAM Aluminum

The symmetrical nature in the case of wall fabrication by wire arc additive manufacturing (WAAM) has been observed in the literature, but it has not been studied as a source of knowledge. This paper focuses on the comparative study of three drop transfer methods employing Gas Metal Arc Welding (GMAW) technology, one of the most reported for the manufacture of aluminum alloys. The transfer modes studied are the well-known pulsed GMAW, cold arc, and the newer pulsed AC. The novelty of the last transfer mode is the reversal of the polarity during the preparation phase of the substance for droplet deposition. This study compares the symmetry of zero beads to determine the best parameters and transfer modes for wire arc additive manufacturing of 5 series aluminum. The pulsed transfer modes show values of 0.6 for symmetry ratio, which makes them more interesting strategies than cold arc with a symmetry ratio of 0.5. Furthermore, the methodology proposed in this study can be extrapolated to other materials manufactured with this technology.The authors acknowledge the Basque Government for financing the HARIPLUS, HAZITEK 2019 program (ZL-2019/00352), and QUALYFAM project (kk-2020/00042)