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Dissertations / Theses on the topic 'Amplitude and height parameters'
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1
Fuciman, Lukáš. "Rozbor a zhodnocení vlivů textury povrchu zkušebních vzorků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417440.
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The thesis deals with an evaluation of the surface texture of various materials, created by machining technologies (turning, milling and grinding). As for the theoretical part of the thesis, it contains a theoretical analysis of the effect of surface texture on friction, wear, coating and lubricating properties. The main emphasis is put on the analysis of the most frequently evaluated profile and surface parameters as well as their possible influence on the functional areas of machined parts. The experimental part includes evaluated and compared measured data based on the monitored parameters with benefits for machinery industry.
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Škeřík, Filip. "Hodnocení vlivu technologií obrábění na analýzu textury povrchu technických plastů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443214.
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The diploma thesis deals with the influence of machining technologies (turning, milling, grinding and polishing) on the surface texture of functional surfaces of selected materials from technical plastics. In the first part of the thesis there is a theoretical analysis of the possibilities of machining plastic materials. Furthermore, an analysis of the most commonly used parameters for evaluating the roughness of the machined surface and their effect on functionality is performed. The experimental part of the thesis describes samples preparation, analysis of measured data and subsequent evaluation with benefits for machinery industry.
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Richardson, Stephen Jon. "Acoustical parameters for the classical guitar." Thesis, Cardiff University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390804.
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Vural, Aydin. "Precise Height Estimation By Differential Amplitude Measurement For An Airborne Cw Doppler Proximity Sensor." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614956/index.pdf.
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Airborne CW doppler proximity sensors are very sensitive, but leaks precise height measurement. It may be possible to estimate the heigth at the terminal phase (the case where the sensor is at a heigth close to ground) precisely by using the doppler shift and amplitude information. The thesis includes this novel concept with theoritical analysis and simulation results.
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Elia, Letizia. "PCA study of the interannual variability of the GPS height and environmental parameters." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20438/.
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The objective of this study is to investigate a large network of GPS stations to identify and analyze spatially coherent signals present in the Up coordinate time series of the stations and, at the same locations, to identify and analyze common patterns in the series of environmental parameters and climate indices. The study is confined to Europe and the Mediterranean area, where 107 GPS sites were selected from the archive of the Nevada Geodetic Laboratory (NGL) on the basis of the completeness and length of the data series. The parameters of interest the Up coordinate of the GPS stations, the surface pressure (SP), the terrestrial water storage (TWS) and various climate indices: NAO (North Atlantic Oscillation), EA (East Atlantic), AO (Artic Oscillation), SCAND (Scandinavia), TNA (Tropical North Atlantic) and MEI v2 (Multivariate ENSO Index version 2). The Principal Component Analysis (PCA) is the methodology adopted to extract the main patterns of the space/time variability of these parameters. The work also focused on the coupled modes of space/time interannual variability between pairs of variables using the Singular Value Decomposition (SVD) methodology. The coupled variability between all the aforementioned parameters is investigated.
This study has identified, over Europe and the Mediterranean, main modes of variability in the time series of the GPS Up coordinate, SP and TWS. The SVD analysis of coupled parameters, namely GPS Up-SP and GPS Up-TWS, showed that most of the common variability is explained by the first 3 modes. Moreover, the correlation between the GPS Up coordinate and the climate indices was estimated to investigate the possible influence of climate variability on the GPS Up behaviour. More than 30 stations, over the total of 107, show significant correlations with the AO, TNA and SCAND indices. The correlation coefficients with MEI v2 turn out to be significant and up to 0.5 for about half of the stations.
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Call, Robert Welch. "The Effect of Growth Parameters on the Height and Density of Carbon Nanotube Forests." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1261.
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Carbon nanotube forests (CNTFs) are grown using an injection chemical vapor deposition method. Images of CNTFs are taken using a scanning electron microscope and are used to measure their height and density. Growth parameters are systematically varied to determine their effect on the height and density of CNTFs. Investigations of CNTF density as a function of distance from the growth substrate reveal that diffusion can be a limiting factor on CNTF growth. Our findings indicate that height and density are related and that each growth parameter has multi-dimensional effects.
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Walter, Fredrik. "Extraction of forest stand parameters from CARABAS VHF SAR images /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5649-5.pdf.
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Popescu, Sorin Cristian. "Estimating Plot-Level Forest Biophysical Parameters Using Small-Footprint Airborne Lidar Measurements." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27109.
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The main study objective was to develop robust processing and analysis techniques to facilitate the use of small-footprint lidar data for estimating forest biophysical parameters measuring individual trees identifiable on the three-dimensional lidar surface. This study derived the digital terrain model from lidar data using an iterative slope-based algorithm and developed processing methods for directly measuring tree height, crown diameter, and stand density. The lidar system used for this study recorded up to four returns per pulse, with an average footprint of 0.65 m and an average distance between laser shots of 0.7 m. The lidar data set was acquired over deciduous, coniferous, and mixed stands of varying age classes and settings typical of the southeastern United States (37° 25' N, 78° 41' W). Lidar processing techniques for identifying and measuring individual trees included data fusion with multispectral optical data and local filtering with both square and circular windows of variable size. The window size was based on canopy height and forest type. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top, by fitting a four-degree polynomial on both profiles. The ground-truth plot design followed the U.S. National Forest Inventory and Analysis (FIA) field data layout. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field inventory data, including volume, basal area, and biomass. FIA subplots of 0.017 ha each were pooled together in two categories, deciduous trees and pines. For the pine plots, lidar measurements explained 97% of the variance associated with the mean height of dominant trees. For deciduous plots, regression models explained 79% of the mean height variance for dominant trees. Results for estimating crown diameter were similar for both pines and deciduous trees, with R2 values of 0.62-0.63 for the dominant trees. R2 values for estimating biomass were 0.82 for pines (RMSE 29 Mg/ha) and 0.32 for deciduous (RMSE 44 Mg/ha). Overall, plot level tree height and crown diameter calculated from individual tree lidar measurements were particularly important in contributing to model fit and prediction of forest volume and biomass.Ph. D.
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Briggs, John Charles. "Force identification using extracted modal parameters, with applications to glide height testing of computer hard disks." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/33250.
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Srivastava, Siddharth. "Assessment of critical parameters that affect the seismic performance of bridge steel pedestals." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3142.
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Gahard, Claude F. "An estimation of the ability to forecast boundary layer mixing height and wind parameters through forecast verification over Fort Ord." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FGahard.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2003.Thesis advisor(s): Wendell A. Nuss, David S. Brown. Includes bibliographical references (p. 65-66). Also available online.
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Faerber, Timothy. "Chi-Squared Analysis of Measurements of Two Cosmological Parameters Over Time." Thesis, Uppsala universitet, Observationell astrofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-399031.
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For this project, a historical statistical analysis of the Amplitude of Mass Fluctuations ($\sigma_8$) and Hubble's Constant ($H_0$) parameters in the Standard Cosmological Model was carried out to determine whether or not the given error bars truly represent the dispersion of values. It was found through analysis of the Chi-Squared ($\chi^2$) values of the data that for $\sigma_8$ (60 data points and $\chi^2$ between 183.167 and 189.037) that the associated probability Q is extremely low, with $Q = 1.5597*10^{-15}$ for the weighted average and $Q = 1.2107*10^{-14}$ for the best fit of the data. This was also the case for the $\chi^2$ values (163 data points and $\chi^2$ between 484.3977 and 575.655) of $H_0$, where $Q = 4.2176*10^{-34}$ for the linear fit of the data and $Q = 1.0342*10^{-47}$ for the weighted average of the data. Through further analysis, it is shown in question, a linear fit is a better estimate of the data than the weighted average. The general conclusion is that the statistical error bars have been underestimated (in around 20\% of the measurements), or the systematic errors were not properly taken into account.
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Safari, Hanieh [Verfasser]. "Combined use of spectral signatures and ultrasonic sward height for the assessment of biomass and quality parameters in heterogeneous pastures / Hanieh Safari." Kassel : Universitätsbibliothek Kassel, 2017. http://d-nb.info/1154973824/34.
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Erdurmaz, Muammer Sercan. "Neural Network Prediction Of Tsunami Parameters In The Aegean And Marmara Seas." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605134/index.pdf.
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Tsunamis are characterized as shallow water waves, with long periods and wavelengths. They occur by a sudden water volume displacement. Earthquake is one of the main reasons of a tsunami development. Historical data for an observation period of 3500 years starting from 1500 B.C. indicates that approximately 100 tsunamis occurred in the seas neighboring Turkey.
Historical earthquake and tsunami data were collected and used to develop two artificial neural network models to forecast tsunami characteristics for future occurrences and to estimate the tsunami return period. Artificial Neural Network (ANN) is a system simulating the human brain learning and thinking behavior by experiencing measured or observed data.
A set of artificial neural network is used to estimate the future earthquakes that may create a tsunami and their magnitudes. A second set is designed for the estimation of tsunami inundation with relation with the tsunami intensity, the earthquake depth and the earthquake magnitude that are predicted by the first set of neural networks.
In the case study, Marmara and Aegean regions are taken into consideration for the estimation process. Return periods including the last occurred earthquake in the Turkish seas, which was the izmit (Kocaeli) Earthquake in 1999, were utilized together with the average earthquake depths calculated for Marmara and Aegean regions for the prediction of the earthquake magnitude that may create a tsunami in the stated regions for various return periods of 1-100 years starting from the year of 2004. The obtained earthquake magnitudes were used together with tsunami intensities and earthquake depth to forecast tsunami wave height at the coast.
It is concluded that, Neural Networks predictions were a satisfactory first step to implement earthquake parameters such as depth and magnitude, for the average tsunami height on the shore calculations.
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Syed, Riaz. "Development of Computational Tools for Characterization, Evaluation, and Modification of Strong Ground Motions within a Performance-Based Seismic Design Framework." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/36435.
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One of the most difficult tasks towards designing earthquake resistant structures is the determination of critical earthquakes. Conceptually, these are the ground motions that would induce the critical response in the structures being designed. The quantification of this concept, however, is not easy. Unlike the linear response of a structure, which can often be obtained by using a single spectrally modified ground acceleration history, the nonlinear response is strongly dependent on the phasing of ground motion and the detailed shape of its spectrum. This necessitates the use of a suite (bin) of ground acceleration histories having phasing and spectral shapes appropriate for the characteristics of the earthquake source, wave propagation path, and site conditions that control the design spectrum. Further, these suites of records may have to be scaled to match the design spectrum over a period range of interest, rotated into strike-normal and strike-parallel directions for near-fault effects, and modified for local site conditions before they can be input into time-domain nonlinear analysis of structures. The generation of these acceleration histories is cumbersome and daunting. This is especially so due to the sheer magnitude of the data processing involved.
The purpose of this thesis is the development and documentation of PC-based computational tools (hereinafter called EQTools) to provide a rapid and consistent means towards systematic assembly of representative strong ground motions and their characterization, evaluation, and modification within a performance-based seismic design framework. The application is graphics-intensive and every effort has been made to make it as user-friendly as possible. The application seeks to provide processed data which will help the user address the problem of determination of the critical earthquakes. The various computational tools developed in EQTools facilitate the identification of severity and damage potential of more than 700 components of recorded earthquake ground motions. The application also includes computational tools to estimate the ground motion parameters for different geographical and tectonic environments, and perform one-dimensional linear/nonlinear site response analysis as a means to predict ground surface motions at sites where soft soils overlay the bedrock.
While EQTools may be used for professional practice or academic research, the fundamental purpose behind the development of the software is to make available a classroom/laboratory tool that provides a visual basis for learning the principles behind the selection of ground motion histories and their scaling/modification for input into time domain nonlinear (or linear) analysis of structures. EQTools, in association with NONLIN, a Microsoft Windows based application for the dynamic analysis of single- and multi-degree-of-freedom structural systems (Charney, 2003), may be used for learning the concepts of earthquake engineering, particularly as related to structural dynamics, damping, ductility, and energy dissipation.Master of Science
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Sucic, Victor. "Parameters Selection for Optimising Time-Frequency Distributions and Measurements of Time-Frequency Characteristics of Nonstationary Signals." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15834/.
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The quadratic class of time-frequency distributions (TFDs) forms a set of tools which allow to effectively extract important information from a nonstationary signal. To determine which TFD best represents the given signal, it is a common practice to visually compare different TFDs' time-frequency plots, and select as best the TFD with the most appealing plot. This visual comparison is not only subjective, but also difficult and unreliable especially when signal components are closely-spaced in the time-frequency plane. To objectively compare TFDs, a quantitative performance measure should be used. Several measures of concentration/complexity have been proposed in the literature. However, those measures by being derived with certain theoretical assumptions about TFDs are generally not suitable for the TFD selection problem encountered in practical applications. The non-existence of practically-valuable measures for TFDs' resolution comparison, and hence the non-existence of methodologies for the signal optimal TFD selection, has significantly limited the use of time-frequency tools in practice. In this thesis, by extending and complementing the concept of spectral resolution to the case of nonstationary signals, and by redefining the set of TFDs' properties desirable for practical applications, we define an objective measure to quantify the quality of TFDs. This local measure of TFDs' resolution performance combines all important signal time-varying parameters, along with TFDs' characteristics that influence their resolution. Methodologies for automatically selecting a TFD which best suits a given signal, including real-life signals, are also developed. The optimisation of the resolution performances of TFDs, by modifying their kernel filter parameters to enhance the TFDs' resolution capabilities, is an important prerequisite in satisfying any additional application-specific requirements by the TFDs. The resolution performance measure and the accompanying TFDs' comparison criteria allow to improve procedures for designing high-resolution quadratic TFDs for practical time-frequency analysis. The separable kernel TFDs, designed in this way, are shown to best resolve closely-spaced components for various classes of synthetic and real-life signals that we have analysed.
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Bäcklund, Tomas. "Development and validation of a system for clinical assessment of gait cycle parameter in patients with idiopathic normal pressure hydocephalus." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-82891.
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A number of parameters have been identified as characteristic of the walking pattern in patients with INPH. Most of these have been identified through qualitative surveys and manually conducted test batteries. In order to obtain quantitative, standardized and objective measures, which enable studies based on larger patient populations and comparable results, there is a need for a user-friendly system that can measure specific key parameters over time in a reliable manner in everyday clinical work. Step height, width and the variability in the gait cycle are such parameters which are interesting research areas for this group of patient. Problems with balance and gait are very common in other patient groups as well, particularly in neurological diseases such as Parkinson's disease, multiple sclerosis and stroke. This is the reason that the development of this gait analyzer is performed. Giving access to a simple and objective method for estimating gait and balance ability in clinical routine investigations would increase the ability to provide the right kind of treatment, confirm treatment results, and conducting larger research studies. Therefore, this equipment can contribute to the assessment of diseases which contain impaired gait. As a first test of the usability and for the validation of accuracy and repeatability of the equipment a group of healthy volunteers was used. Results from tests on healthy subjects show god repeatability between measurements, for step width at normal gait the difference was -0,2 ±0,34 cm (mean, ±SD) and step height 0,69 ±3,34 cm. The stride time variability in the healthy group where very small 0,00048 ±0,00028 s2 with a difference between test of 0,000019 ±0,00038 s2. Three pilot patients have been tested where we have clearly seen indications of increased stride time variability and reduced step height.
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Shrestha, Manoj. "Partial-wave Analysis of πN Scattering to ηN and KΛ Final States and Extraction of Resonance Parameters from Unitary, Multichannel Fits." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1353095268.
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Andreassen, Rolf. "Study of D0-D̅0 mixing parameters using a time-dependent amplitude analysis of the decay D0 to KS0 π+ π−." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1285687286.
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Schnell, Thomas. "Legibility optimization of uppercase alphanumeric text for displaying messages in traffic applications." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1175194520.
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Fachada, Ivone. "Estudo da adaptabilidade da Quercus suber L. no Nordeste Transmontano." Master's thesis, Universidade dos Açores, Instituto Politécnico de Bragança, 2006. http://hdl.handle.net/10198/1039.
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Neste trabalho estuda-se um ensaio de 34 proveniências de Quercus suber L. oriundas
da bacia mediterrânica, com 7 anos de idade, com vista à definição da sua
adaptabilidade às condições edafo-climáticas do Nordeste Transmontano, uma vez que a
maioria da variação das características relacionadas com a adaptabilidade é ao nível da
proveniência. Avalia-se a variabilidade inter-proveniência e a plasticidade fenotípica do
crescimento, sobrevivência e estrutura morfológica.
Os resultados obtidos no ensaio de proveniências mostram que existe variabilidade na
adaptabilidade entre as várias proveniências analisadas, para todas as características em
estudo. Nesta fase, as populações marroquinas apresentam o maior crescimento médio
em altura, seguidas de duas populações espanholas. Relativamente aos diâmetros, há
três proveniências espanholas que se destacam das restantes por possuírem um maior
crescimento médio em diâmetro.
Os resultados evidenciam ainda que a Quercus suber L. é uma espécie capaz de gerar
populações muito diversas e com indivíduos diferenciados em que existe uma elevada
variabilidade genética. Assim sendo, é necessário estar atento à escolha das populações
a utilizar no futuro para acções de repovoamento, com vista a seleccionar os indivíduos
que terão mais hipóteses de sucesso na sua adaptação e desta forma aumentar o
potencial produtivo do sobreiro com especial relevo para a produção de cortiça e criar
condições para o fornecimento abundante e regular de material reprodutivo de provada
qualidade genética.In this research we studied a trial with 34 provenances of Quercus suber L. from the Mediterranian Basin, with seven years old, to determine which provenances adapt better to the climate and soil conditions of the Northeast of Trás-os.Montes, because most of the variation of the characteristics related with adaptability relies at the provenance level. We evaluate the inter-provenance variation and the phenotypic plasticity of growth, survival and morphology structure. The results obtained in the provenance trial show that there is variability in adaptability among the several provenances tested for all variables. At this stage, marroquin populations present the higher medium growth in height. In diameter, three spanish populations present the higher values for medium growth. The results also show that the Quercus suber L. is a species able to generate many different populations, with many different individuals, in which the genetic variability is very high. Therefore, is necessary to choose carefully the populations we’ll use in the future in reforestation, choose individuals with more survival success and adaptation so we can improve the productive potential of the cork oak, specially in the cork production and create conditions for the regular supply of reproductive material of good genetic quality.
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Almén, Anton. "Importance of atomic force microscopy settings for measuring the diameter of carbon nanotubes." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-74745.
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Carbon nanotubes (CNTs) have gathered a lot of interest because of their extraordinary mechanical, electrical and thermal properties and have potential applications in a wide variety of areas such as material-reinforcement and nano-electronics. The properties of nanotubes are dependent on their diameter and methods for determining this using atomic force microscopy (AFM) in tapping mode assume that the measured height of the tubes represent the real diameter. Based on early, faulty calculations, the forces in tapping mode were assumed to be much lower than in contact mode, however it was later shown that forces in tapping mode can at point of impact rival the forces present in contact mode. This means that there is a potential risk of tube deformation during tapping mode measurements, resulting in incorrectly determined diameters. This work studies CNTs deposited on a silicon-substrate to analyze the effect of three common AFM settings (tapping frequency, free oscillation amplitude and setpoint) to determine their effect on measured CNT diameters and recommendations for choosing settings are given.Kolnanorör har skapat mycket intresse på grund av sina extraordinära mekaniska, elektriska och termiska egenskaper och har lovande tillämpningar inom en mängd olika områden så som materialförstärkning och nanoelektronik. Kolnanorörens egenskaper påverkas kraftigt av deras diameter och de metoder som använder sig av atomkraftsmikroskopi(AFM) för att mäta diametern hos rören antar att den höjd-data man får fram är ett bra mått på den verkliga diametern hos rören. Baserat på tidiga, felaktiga beräkningar, antog man att kraften i ’tapping mode’ skulle vara mycket lägre än i ’contact mode’ vilket skulle leda till att man inte deformerar ytan man undersöker. Senare forskning visade att kraften mellan spets och prov kan vara lika stor eller rentutav större i tapping mode än i contact mode under det ögonblick då spetsen slår ner i provytan. Det medför att det finns en potentiell risk för att man deformerar kolnanorören när man mäter på dom vilket skulle resultera i att man får felaktiga värden på deras diametrar. Under det här projektet har kolnanorör som placerats på ett kisel-substrat undersökts för att analysera hur tre vanliga inställningar hos AFMet påverkar de erhållna värdena för diametern hos kolnanorören. De tre inställningarna som testats är svängnings-frekvensen, svängnings-amplituden i luft och börvärdet hos svängnings-amplituden.
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Ivan, Pinćjer. "Razvoj dinamičkog modela kontrole procesnih parametara postupaka rastriranja i njihov uticaj na otisak kao stimulus." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=96011&source=NDLTD&language=en.
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U disertaciji su prikazana istraživanja vezana za objektivnu i subjektivnu,psihofizičku metodu koja u eksperimentu utvrđuje koliki uticaj imaju različitiparametri rasterizacije kao i dimenzija posmatrane slike na percepcijurealističnog prikaza i zrnaste strukture uz poređenje sa objektivnim metodamaobuhvaćenim eksperimentalnim merenjima. U metodologiji istraživanja sukorišćeni uzorci rastrirani sa dva različita tipa rastera frekventnomodularni i amplitudno modularni. Poznatim i priznatim naučnim metodimaobrade podataka došlo se do relevantnih rezultata koji potvrđuju različitostposmatranih reprodukcija i model kontrole parametara rasterizacije.The research presented in this dissertation is related to the image reproduction qualityassessment. Dissertation was designed to determine the impact of halftone attributeson image quality. Objective and subjective quality assessment results were designedto complement recently published findings for quality assessment. These attributes aredirectly dependent on the chosen halftoning method. In this research the samples werehalftoned using two different types of screening methods: frequency modulated andamplitude modulated method. Experiment data samples, were analysed by adequatestatistical methods. Results indicate significant influence of halftoning method on thequality assessment and defines control model.
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Ruchert, Cassius Olivio Figueiredo Terra. "Estudo da inferência de carregamento em histórias de vôos simulados na liga de Al aeronáutico SAE-AMS 7475 T7351." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-22092008-131854/.
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Este trabalho discutiu o estudo da inferência de carregamento e a reconstrução fratográfica da taxa de propagação da trinca por fadiga em histórias de vôos simulados do tipo Twist, mini-Twist, Falstaff e mini-Falstaff. O material estudado foi uma liga de alumínio de grau aeronáutico SAE-AMS 7475 T7351 na qual foram obtidas as propriedades mecânicas a partir dos ensaios de tração e dureza, análise química, metalográfica. Foram realizados ensaios de amplitude constante de carregamento em corpos de prova com geometria tipo C(T) extraídos de um bloco e ensaios de amplitude variável em corpos de prova com geometria tipo M(T) extraídos de uma placa. Corpos de prova do tipo C(T) foram extraídos da orientação L-T e T-L, à temperatura ambiente com diferentes espessuras para a realização de ensaios de propagação de trinca por fadiga (da/dN vs. ΔK) com distintos valores de razão de carregamento,R (0,1;0,3; 0,5; 0,7 e 0,8) de acordo com a norma ASTM-E647 (1993). Foram realizados dois tipos de ensaios de fadiga com amplitude constante de carregamento. Primeiro, o ensaio com ΔP constante para obtenção dos dados dos estágios II e III das curvas da/dN vs. ΔK para distintos valores de R e, posteriormente, o ensaio com ΔK constante e R crescente para ser utilizado no estudo da inferência de carregamento de amplitude constante a partir da relação entre a morfologia da estria, H/s e a razão de carregamento R. Adicionalmente foram realizados ensaios de tenacidade à fratura, nas direções L-T e T-L, conforme a norma ASTME1820 (1999). As taxas de propagação macroscópica e microscópica foram comparadas e boas correlações foram obtidas para um intervalo entre 0,1 a 1,0 μm/ciclo, mesmo com distintos R. Através da técnica proposta por Berkovitz (1995), o espectro de carregamento foi estimado para distintos valores de R, através da técnica de parametrização do fator K e os resultados foram comparados ao espectro de carregamento real imposto pela máquina de ensaio. Após os ensaios de amplitude constante de carregamento foram realizados ensaios de amplitude variável com a aplicação em corpos de prova M(T) de espectros de vôos simulados padronizados pela NLR do tipo Twist e Falstaff e seus vôos reduzidos, mini-Twist e mini- Falstaff, em uma máquina servohidráulica de ensaios dinâmicos. A partir destes ensaios notou-se que suprimir os vôos com os carregamentos menos severos influencia muito a vida da propagação da trinca de fadiga, quando vôos simulados do tipo Twist e mini-Twist, fato este não observado para o Falstaff e mini-Falstaff. Foi possível observar também o efeito da aceleração e desaceleração da trinca por fadiga observando os gráficos de d2a/dvôo vs. a obtidos dos ensaios de amplitude variável. Foi realizado um estudo da superfície de fratura do CP05 por meio da técnica fractográfica do reconhecimento de blocos marcadores sendo possível mostrar uma satisfatória reconstituição da taxa de propagação da trinca por fadiga de vôo simulado do tipo Falstaff por meio de medidas das marcações na superfície de fratura dos vôos mais severos, realizadas em imagens obtidas por MEV.The loading inference and the fractographic reconstruction of fatigue crack propagation rate in simulated flight stories, as Twist, mini-Twist, Falstaff and mini-Falstaff were investigated in this work. The studied material was an aluminum alloy SAE-AMS 7475 T7351. Tensile and hardness tests were carried out in order to determine mechanical properties, as well as chemical and microstructure analysis of the material. C(T) specimens were extracted from a block of material for constant amplitude load testing and M(T) specimens were extracted from a plate and were tested in variable amplitude loading. The curves (da/dN vs. ΔK) for constant-amplitude loading were obtained from fatigue crack propagation tests performed in L-T and T-L directions in C(T) specimens for R (0.1; 0.3; 0.5; 0.7 and 0.8), at room temperature, according to ASTM-E647 (1993). Two different constant loading fatigue tests were performed. At constant ΔP and distinct values of R for obtaining data of stages II and III of da/dN - ΔK curves; and at constant ΔK and increasing the R ratio to be used in the inference of constant amplitude loading in the relation of H/s striation morphology (obtained from fractographic images) and the loading ratio, R. Additionally, fracture toughness tests were executed in T-L and L-T directions, according to ASTM-E1820 (1999). The macroscopic and microscopic fatigue crack propagations were compared and good correlation was obtained for the range 0.1-1.0 μm/cycle, for all R values. By using the K factor parametrization method, Berkovitz (1995), the loading spectrum was estimated for the distinct R-values and the results were compared to the actual spectrum imposed by the test machine. Variable amplitude tests were performed in M(T) specimens by applying simulating flight spectra normalized by NLR, as Twist, mini-Twist, Falstaff and mini-Falstaff, in a servohydraulic test machine MTS, in which a Flextest GT controller was coupled. The suppression of less severe loading flights showed a great influence in fatigue crack propagation life, in simulated flight tests Twist and mini-Twist, but not in Falstaff and mini-Falstaff. The acceleration and slowing down of fatigue crack were observed in the d2a/dflight - a curve obtained from variable loading tests. The fractured surfaces of some samples were examined by the fractographic technique of blocking marks recognition. A good reconstitution of fatigue crack propagation rate of a simulated flight like Falstaff was obtained by the measurements of marks in the fracture surfaces of the more severe flights, in MEV images.
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Bienert, Anne, Louis Georgi, Matthias Kunz, Hans-Gerd Maas, and Oheimb Goddert von. "Comparison and Combination of Mobile and Terrestrial Laser Scanning for Natural Forest Inventories." Molecular Diversity Preservation International MDPI, 2018. https://tud.qucosa.de/id/qucosa%3A31826.
Full textAbstract:
Terrestrial laser scanning (TLS) has been successfully used for three-dimensional (3D) data capture in forests for almost two decades. Beyond the plot-based data capturing capabilities of TLS, vehicle-based mobile laser scanning (MLS) systems have the clear advantage of fast and precise corridor-like 3D data capture, thus providing a much larger coverage within shorter acquisition time. This paper compares and discusses advantages and disadvantages of multi-temporal MLS data acquisition compared to established TLS data recording schemes. In this pilot study on integrated TLS and MLS data processing in a forest, it could be shown that existing TLS data evaluation routines can be used for MLS data processing. Methods of automatic laser scanner data processing for forest inventory parameter determination and quantitative structure model (QSM) generation were tested in two sample plots using data from both scanning methods and from different seasons. TLS in a multi-scan configuration delivers very high-density 3D point clouds, which form a valuable basis for generating high-quality QSMs. The pilot study shows that MLS is able to provide high-quality data for an equivalent determination of relevant forest inventory parameters compared to TLS. Parameters such as tree position, diameter at breast height (DBH) or tree height can be determined from MLS data with an accuracy similar to the accuracy of the parameter derived from TLS data. Results for instance in DBH determination by cylinder fitting yielded a standard deviation of 1.1 cm for trees in TLS data and 3.7 cm in MLS data. However, the resolution of MLS scans was found insufficient for successful QSM generation. The registration of MLS data in forests furthermore requires additional effort in considering effects caused by poor GNSS signal.
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Molčan, Vladimír. "Určení prostorových vztahů jeřábové dráhy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-227104.
Full textAbstract:
The main theme of this master thesis is the design of technological process measurement and processing of measured data entered crane tracks to determine the geometric parameters of these crane tracks. Diploma thesis further describes the procedure for testing and possible rectification surveying equipment and instrumentation. The thesis is divided of 7 parts, contains 31 images, 4 graphs, 44 tables and 13 attachments. The theoretical part of this thesis contains information about several types of cranes, methods of measurement and processing, as well information on legal and technical regulations related to this topic of the thesis. The fourth and fifth parts of this thesis provides information on selected crane tracks on which the measurements were taken, the choice of methods of measurement, processing technique and the results obtained. The final part of the thesis includes evaluation of the results obtained, comparing methods of measurement, processing, evaluation and design of a technique of determining the geometric parameters of crane tracks.
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Pelteku, Altin E. "Adaptive Suppression of Interfering Signals in Communication Systems." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/138.
Full textAbstract:
The growth in the number of wireless devices and applications underscores the need for characterizing and mitigating interference induced problems such as distortion and blocking. A typical interference scenario involves the detection of a small amplitude signal of interest (SOI) in the presence of a large amplitude interfering signal; it is desirable to attenuate the interfering signal while preserving the integrity of SOI and an appropriate dynamic range. If the frequency of the interfering signal varies or is unknown, an adaptive notch function must be applied in order to maintain adequate attenuation. This work explores the performance space of a phase cancellation technique used in implementing the desired notch function for communication systems in the 1-3 GHz frequency range. A system level model constructed with MATLAB and related simulation results assist in building the theoretical foundation for setting performance bounds on the implemented solution and deriving hardware specifications for the RF notch subsystem devices. Simulations and measurements are presented for a Low Noise Amplifer (LNA), voltage variable attenuators, bandpass filters and phase shifters. Ultimately, full system tests provide a measure of merit for this work as well as invaluable lessons learned. The emphasis of this project is the on-wafer LNA measurements, dependence of IC system performance on mismatches and overall system performance tests. Where possible, predictions are plotted alongside measured data. The reasonable match between the two validates system and component models and more than compensates for the painstaking modeling efforts. Most importantly, using the signal to interferer ratio (SIR) as a figure of merit, experimental results demonstrate up to 58 dB of SIR improvement. This number represents a remarkable advancement in interference rejection at RF or microwave frequencies.
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Scarfe, Bradley Edward. "Oceanographic Considerations for the Management and Protection of Surfing Breaks." The University of Waikato, 2008. http://hdl.handle.net/10289/2668.
Full textAbstract:
Although the physical characteristics of surfing breaks are well described in the literature, there is little specific research on surfing and coastal management. Such research is required because coastal engineering has had significant impacts to surfing breaks, both positive and negative. Strategic planning and environmental impact assessment methods, a central tenet of integrated coastal zone management (ICZM), are recommended by this thesis to maximise surfing amenities. The research reported here identifies key oceanographic considerations required for ICZM around surfing breaks including: surfing wave parameters; surfing break components; relationship between surfer skill, surfing manoeuvre type and wave parameters; wind effects on waves; currents; geomorphic surfing break categorisation; beach-state and morphology; and offshore wave transformations. Key coastal activities that can have impacts to surfing breaks are identified. Environmental data types to consider during coastal studies around surfing breaks are presented and geographic information systems (GIS) are used to manage and interpret such information. To monitor surfing breaks, a shallow water multibeam echo sounding system was utilised and a RTK GPS water level correction and hydrographic GIS methodology developed. Including surfing in coastal management requires coastal engineering solutions that incorporate surfing. As an example, the efficacy of the artificial surfing reef (ASR) at Mount Maunganui, New Zealand, was evaluated. GIS, multibeam echo soundings, oceanographic measurements, photography, and wave modelling were all applied to monitor sea floor morphology around the reef. Results showed that the beach-state has more cellular circulation since the reef was installed, and a groin effect on the offshore bar was caused by the structure within the monitoring period, trapping sediment updrift and eroding sediment downdrift. No identifiable shoreline salient was observed. Landward of the reef, a scour hole ~3 times the surface area of the reef has formed. The current literature on ASRs has primarily focused on reef shape and its role in creating surfing waves. However, this study suggests that impacts to the offshore bar, beach-state, scour hole and surf zone hydrodynamics should all be included in future surfing reef designs. More real world reef studies, including ongoing monitoring of existing surfing reefs are required to validate theoretical concepts in the published literature.
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PEI-TE, Huang, and 黃培德. "Prediction of Optimal Pillow Height by Anthropometric Parameters." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/69750091632907281597.
Full textAbstract:
碩士長庚大學
復健科學研究所
95
Background：Almost one third of our life is spent on sleep. In recent years, people change lifestyle because of too many activities, sleep time is compressed to lesser and lesser. How to improve the quality of sleep in such a limited duration of time will be a very important issue. According to the previous studies, the quality of sleep may be influenced by many factors. Good pillow is an essential factor to help maintain natural cervical lordosis for good sleep. Good pillow should provide well support of head and neck to improve the quality of sleep. There are a wide variety of pillows available on the market today in different materials, shapes and sizes. However, there is not enough scientific evidence to find out the indicator for good fit of pillow. The purpose of this study will be focus on the viewpoint of optimal height of pillow for good sleep. Method：Sixty subjects who were healthy adults（male and female in equal numbers） without any pathological neck pain or sleep apnea were invited to join this study. Pittsburg Sleep Quality Index was applied for assessment of sleep quality. Manual anthropometric measurement from shoulder, head and neck were recorded. 3D scanning body measurement was also applied for comparison with manual measure. Regression analyses were used to estimate relationships among all measured parameters. Results：There were some difference in the prediction of full model of pillow height in male and female. The half shoulder length and whole maximal shoulder length were very important to determine the pillow height, and influenced by body weight too. The prediction equation of pillow height should be normalized by body weight in different parameters. Discussion and clinical relevance: This study proved that anthropometric parameters were correlated to the pillow height. The pillow height was between 9-11cm and 9-11.5cm in supine and side lying for comfortable sleep. We proposed a model for measuring optimal pillow height according to parameters by manual measure as well 3D scanning method.
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Ngqungqa, Sphiwe Hamilton. "A critical evaluation and analysis of methods of determining the number of times that lightning will strike a structure." Thesis, 2006. http://hdl.handle.net/10539/1594.
Full textAbstract:
Faculty of Engineering & Built Environment, School of Electrical & Info Engineering, DissertationThe primary objective of this paper is to present results regarding data obtained from Eskom’s Lightning Positioning and Tracking System (LPATS) and is a continuation of the work presented at the two SAUPEC Conferences in Pretoria and Stellenbosch [1, 2]. LPATS provides some useful information regarding the lightning field measurements around the Brixton and Hillbrow Towers, in Johannesburg, for the two seasons of June 2001 to June 2003. The results suggest that there is a significant increase in apparent ground flash density in the vicinity of the towers when compared to the surrounding areas. The observation of mean current values in the order of -20kA suggests that the increased contribution of upward flashes to the total incidence of flashes in tall structures should lead to a decrease in measured current amplitudes.
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Wei, Hsiang-Chun, and 魏祥鈞. "TN-LCD Optical Parameters Measurement Using an Amplitude Sensitive Interferometric Ellipsometer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/38548461598121729188.
Full textAbstract:
碩士國立陽明大學
生醫光電工程研究所
95
To compare with conventional method of measuring twisted nematic liquid crystal (TN-LC) cell parameters, this research proposes an amplitude–sensitive heterodyne interferometric ellipsometer to determine cell parameters precisely based on single wavelength at normal incidence. The advantage of this method is the capability of two dimensional (2-D) distribution measurement using CCD camera. We rotate a quarter wave plate (QWP) which is used to modulate the polarization state of incident laser beam prior to TN-LC in order to obtain a set of amplitude ratio of S- and P-waves versus rotation angle. Thus, the twisted angle Φ, untwisted phase retardation Γ, direction angleα and cell gap d of TN-LC are able to be obtained by using least square fitting algorithm. In this experiment, 0.25% of amplitude-ratio stability in 6 mins was achieved.
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Bac, Nguyen Phuong, and 阮方北. "Effects of Geometric Parameters on Pin Fin Height of Micro Cold Forged Heat Sinks." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/69369385287199045855.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系碩士班
96
A heat sink usually consists of a metal structure with one or more flat surfaces to ensure good thermal contact with the components to be cooled, and an array of pin or fin protrusions to increase the surface contact with the air, and thus the rate of heat dissipation. Heat sinks are widely used in electronic products and have become almost essential to modern central processing units. As the size of many electronic products is being reduced, the development of new techniques for manufacturing the micro heat sink is widely interested in both academia and industry. This study proposed a micro cold forging technique for the manufacturing of the heat sink with an array of pins. Four sets of punches and dies were designed to forge a 6 by 6 mm heat sinks with different number of pins for the material of copper C1100. The study investigated the effects of geometric parameters on the pin fin height and the relationship between the filling and the density of the pins. The studied parameters include the draft angle and the number of pins on the heat sink. By using a simulation approach, it is possible to understand the metal flow during the forging process of the micro heat sink. The predicted results including stress distribution, the forging load and the die filling were then carefully investigated, and could be basic knowledge to help designer in the development of other similar products. The study concludes that the pin fin height of the micro heat sink pin is affected by the draft angle and its difference between the maximum and minimum values can be reduced by using a smaller draft angle.
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Tung, Yuan-Fu, and 董元富. "Investigation on Schottky barrier height modulation of Ni/Ge and extraction of different parameters." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/sp4e79.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
107
In order to improve the performance and meet the requirements as transistors scale down, we are not only changing the structure of transistor, but also seeking the material with high mobility for Post-Silicon. As a result, Si can be replaced by Ge or GeSn due to its small energy gap and its high mobility. However, Fermi level pinning effect exists in metal and Ge contact, which results in higher contact resistance caused by Schottky barrier. So, this is one of the major problems when scaling down. In this thesis, Sn is used to modulate the physical properties such as band gap, the Schottky barrier height can be reduced by inserting n-GeSn epitaxial layer. We use molecular beam epitaxy to grow the n-type GeSn epitaxial layer on the n-type Ge substrate. After the epitaxy process, the non-destructive X-ray diffraction was used to measure the reciprocal space mapping of the epitaxial film, which can ensure the stress, material quality and Tin concentration. When we measured the electrical characteristics of the contact, the series resistance, saturation current and reverse leakage current increased due to the additional GeSn layers. Therefore, we simulate the current-voltage characteristic curve of the Schottky barrier, establishing a current-voltage model under different conditions. Also, we provide an optimization method of parameter extraction. The extraction and optimization methods help to verify the source of error under different characteristics, and obtain the model parameters with high reliability as the basis for experimental results and discussion. We have experimented with two kinds of junctions, NiGe/n-Ge, NiGeSn/n-GeSn by measuring its current-voltage curve under different temperatures. After measurements, we extracted the electrical parameters and made a comparison. We found that the additional n-GeSn layer lowers the average barrier, and the variation of barrier is smaller under different temperatures. Also, the junction with metal is more uniform and more stable in the process.
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Chien, Miin-chang, and 簡敏昌. "A Study on VQ/HMM Based Methods for Syllable Duration and Amplitude Parameters Generation." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/67649345549540340518.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
88
Syllable duration and amplitude are two important prosodic parameters for Mandarin text-to-speech because they have much influence on the fluency and naturalness of the synthesized speech. In this thesis, a method based on vector quantization(VQ) and hidden Markov model(HMM) is used to model syllable duration and amplitude separately. For convenience, the two models for duration and amplitude are together called DA-HMM. In the training phase for DA-HMM, the durations and amplitudes of the syllables comprising each training sentence are normalized first. Then, the average duration and amplitude for each kind of syllable and syllable-final are computed from the normalized training syllables. According to these average values, the 410 kinds of syllables and 37 kinds of syllable-finals are classified respectively by using vector quantization. The VQ codes of adjacent syllables in a training sentence are then combined to form the observation syllable sequence for HMM training. In the synthesis phase, the information of word-boundary and breath-group from text-processing stage are used to arrange the state transition sequence for DA-HMM. Then, according to the assigned state and the encoded observation symbol, the duration and amplitude parameters of each syllable in a sentence to be synthesized can be look up from auxiliary parameters ,of DA-HMM, estimated in the training phase. To study the performance of DA-HMM, we have conducted several experiments. The results show that for inside test, the average prediction errors of a syllable’s duration and amplitude are 43 ms and 1.1dB respectively, and that for outside test, the average prediction errors of a syllable’s duration and amplitude are 22 ms and 2.2 dB respectively.
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Ramberg, Andreas. "Ocean Waves Estimation : An Artificial Intelligence Approach." Thesis, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-35736.
Full textAbstract:
This thesis aims to solve the mathematical inverse problem of characterizing sea waves based on the responses obtained from a marine vessel sailing under certain sea conditions. By researching this problem the thesis contributes to the marine industry by improving products that are using ocean behavior for controlling ship's dynamics. Knowledge about the current state of the sea, such as the wave frequency and height, is important for navigation, control, and for the safety of a vessel. This information can be retrieved from specialized weather reports. However, such information is not at all time possible to obtain during a voyage, and if so usually comes with a certain delay. Therefore this thesis seeks solutions that can estimate on-line the waves' state using methods in the field of Artificial Intelligence. The specific investigation methods are Transfer Functions augmented with Genetic Algorithm, Artificial Neural Networks and Case-Based Reasoning. These methods have been configured and validated using the n-fold cross validation method. All the methods have been tested with an actual implementation. The algorithms have been trained with data acquired from a marine simulation program developed in Simulink. The methods have also been trained and tested using monitored data acquired from an actual ship sailing on the Baltic Sea as well as wave data obtained from a buoy located nearby the vessel's route. The proposed methods have been compared with state-of-the art reports in order evaluate the novelty of the research and its potential applications in industry. The results in this thesis show that the proposed methods can in fact be used for solving the inverse problem. It was also found that among the investigated methods it is the Transfer Function augmented with Genetic Algorithm which yields best results. This Master Thesis is conducted under the Master of Engineering Program in Robotics at Mälardalens högskola in Västerås, Sweden. The thesis was proposed by Q-TAGG R&D AB in Västerås, Sweden, a company which specializes in marine vessel dynamics research.
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Mutlu, Muge. "Estimating Canopy Fuel Parameters with In-Situ and Remote Sensing Data." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8810.
Full textAbstract:
Crown fires, the fastest spreading of all forest fires, can occur in any forest type
throughout the United States and the world. The occurrence of crown fires has become
increasingly frequent and severe in recent years. The overall aim of this study is to
estimate the forest canopy fuel parameters including crown base height (CBH) and
crown bulk density (CBD), and to investigate the potential of using airborne lidar data in
east Texas. The specific objectives are to: (1) propose allometric estimators of CBD and
CBH and compare the results of using those estimators to those produced by the
CrownMass/FMAPlus software at tree and stand levels for 50 loblolly pine plots in
eastern Texas, (2) develop a methodology for using airborne light detection and ranging
(lidar) to estimate CBD and CBH canopy fuel parameters and to simulate fire behavior
using estimated forest canopy parameters as FARSITE inputs, and (3) investigate the use
of spaceborne ICEsat /GLAS (Ice, Cloud, and Land Elevation Satellite/Geoscience Laser
Altimeter System) lidar for estimating canopy fuel parameters. According to our results
from the first study, the calculated average CBD values, across all 50 plots, were 0.18 kg/m³ and 0.07 kg/m³, respectively, for the allometric equation proposed herein and
the CrownMass program. Lorey’s mean height approach was used in this study to
calculate CBH at plot level. The average height values of CBH obtained from Lorey’s
height approach was 10.6 m and from the CrownMass program was 9.1 m. The results
obtained for the two methods are relatively close to each other; with the estimate of CBH
being 1.16 times larger than the CrownMass value. According to the results from the
second study, the CBD and CBH were successfully predicted using airborne lidar data
with R² values of 0.748 and 0.976, respectively. The third study demonstrated that
canopy fuel parameters can be successfully estimated using GLAS waveform data; an R²
value of 0.84 was obtained. With these approaches, we are providing practical methods
for quantifying these parameters and making them directly available to fire managers.
The accuracy of these parameters is very important for realistic predictions of wildfire
initiation and growth.
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Loadman, Pamela M. "Effects of specific rhythmic arm cycling parameters on the amplitude modulation of the Soleus H-reflex." Thesis, 2006. http://hdl.handle.net/1828/1884.
Full textAbstract:
Rhythmic locomotor activity involving the arms or the legs results in task and phase specific Hoffmann (H)-reflex modulation between the two arms or between the two legs. As well, specific ipsilateral and contralateral movement effects are observed. Recently it has been found that there is also interlimb (between arms and legs) task modulation of the H-reflex, using a rhythmic arm cycling paradigm. That is, the stationary Soleus H-reflex amplitude during arm cycling was attenuated when compared to a static condition (Frigon et al. 2004). The specific parameters of the arm cycling movement which may contribute to this attenuation however are unknown. The purpose of this research was to examine whether the interlimb Soleus H-reflex suppression is specific to: the phase of the arm movement; the movement of both arms; arm excursion; and, rate of arm cycling. Participants sat in a custom designed chair to prevent leg and trunk movement and performed bilateral arm cycling at frequencies of 1 and 2 Hz and with short and long crank lengths (to alter arm range of motion; ROM). As well. ipsilateral (relative to leg stimulated) and contralateral single arm cycling were performed at 1Hz with a long crank length. The Tibial nerve at the popliteal fossa was stimulated psuedorandomly at four phases of the arm cycle and changes in the Soleus H-reflex were recorded while maintaining a small, but stable motor (M)-wave for all trials. EMG was recorded from the Soleus, Tibialis Anterior. Vastus Lateralis and the Anterior Deltoid muscles. Peak to peak amplitudes of the H-reflex from each participant were determined off line and normalized to the M-max determined from individual M-H recruitment curves. Results indicate comparable suppressive effects in all phases of the arm movement, and with bilateral or unilateral cycling. The large ROM and the 2 Hz frequency of movement resulted in a stronger inhibition than with the small ROM and the 1 Hz arm cycling. This suggests that neural processes associated with generating both the rhythmic arm cycling pattern and the peripheral feedback from the arms, have an effect on the H-reflex modulation in the legs. We conclude that a general, rather than a specific, signal related to rhythmic arm muscle activity mediates the suppression of Soleus H-reflex during arm cycling.
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Chiu, Su-Chin, and 邱書瑾. "Influence of Amplitude-related Perfusion Parameters in the Parotid Glands by Non-fat-saturated Dynamic Contrast-enhanced Magnetic Resonance Imaging." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/47995338638848513775.
Full textAbstract:
博士國立臺灣大學
生醫電子與資訊學研究所
104
Purpose: To investigate the discrepancy of perfusion parameters of the parotid gland acquired by fat-saturated (FS) versus non-fat-saturated (NFS) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Materials and Methods: Approved by a local institutional review board with written informed consent obtained, this study consisted of three parts. First, a retrospective study analyzed DCE-MRI data previously acquired using NFS (18 patients) or FS scans (18 patients). Second, a phantom study simulated the signal enhancements in the presence of Gd contrast agent at 6 different concentrations and 3 different fat contents. Finally, a prospective study recruited 9 healthy volunteers to investigate the influence of fat suppression on perfusion quantification on the same subjects. T tests and linear regression analysis were used for statistical analysis with Bonferroni correction applied for multiple comparisons. Results: Patients undergoing NFS DCE-MR scan showed significantly lower parameter A (5.08±2.95 a.u.), peak enhancement (PE) (34.44±12.48%), and slope (1.08±0.60%/s) as compared to 8.90±4.03 a.u., 74.55±13.79%, and 1.79±0.85%/s, respectively, in those with FS scan (all P<0.0167). Phantom study showed that the relative signal enhancement was proportional to the dose of gadolinium contrast agent and was higher in FS scan than in NFS scan. Volunteer study showed significantly lower parameter A (6.75±2.38 a.u.), PE (42.12±14.87%), and slope (1.43±0.54%/s) in NFS scan as compared to 17.63±8.56 a.u., 104.22±25.15%, and 3.68±1.67%/s, respectively, in those with FS scan (all P<0.005). These perfusion parameter differences were remedied by using skeletal muscles and pure water as reference on in vivo and phantom studies, respectively. Conclusion: DCE-MRI perfusion characterization is affected by the use of FS on fat-containing tissues such as parotid glands. The use of fat saturation is important to reduce the influence of parotid fat content on perfusion quantification. The selection of a relatively fat-free tissue as baseline is a simple and effective method to reduce bias from fat content in DCE MRI of the parotid glands.
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Rebelo, Carla Cristina Roque. "3D Point Clouds in Urban Planning: Developing and Releasing High-end Methodologies based on LiDAR and UAV Data for the Extraction of Building Parameters." Doctoral thesis, 2016. http://hdl.handle.net/10362/19005.
Full textAbstract:
Os dados geográficos têm um papel determinante na formalização do plano
urbano, enquanto instrumento de planeamento e documento normativo que define
juridicamente as obrigações públicas e vincula os particulares, num determinado
período temporal, no que respeita a disciplina urbanística de uma cidade ou de um
aglomerado urbano, estabelecendo regras de uso e de ocupação do solo. O plano está
associado a um processo, designado processo de planeamento; processo esse que e
constituído por um conjunto de fases, dinâmicas e adaptativas, que se iniciam na sua
elaboração e terminam na avaliação dos desvios entre o determinado no documento
inicial e as metas e objectivos efectivamente atingidos. O plano, o processo e a
praxis do planeamento exigem dados geográficos actualizados a cada instante, quer
para as acções de monitorização quer para os momentos de avaliação.
Um dos aspectos cruciais do plano e a quantificação da volumetria do espaço
edificado existente. Outro aspecto, também fundamental, é o da gestão dessa volumetria;
quer da volumetria existente quer da volumetria adicional. O tema da volumetria
dos espaços edificados tem constituído, aliás, um dos temas mais sensíveis
quando se trata da densificação do espaço urbano existente ou do desenho de novos
espaços urbanos de expansão. Considerando o quadro teórico apresentado, o tema
central da tese trata da modelação de nuvens de pontos 3D obtidas por tecnologia
LiDAR e por UAV, para as aplicações na elaboração do plano e no processo
de planeamento urbano, designadamente quantificação dos parâmetros urbanísticos
altura da fachada e volume dos edifícios.A exploração do tema central da tese suporta-se em dois níveis: o nível da operacionalização e o nível da usabilidade. O nível da operacionalizão concretiza dois
objectivos: i) demonstração da relevância e da pertinência da extracção, medição
e geovisualização 3D dos parâmetros urbanísticos baseadas na experimentação e
implementação de técnicas de geoprocessamento; ii) demonstração da pertinência
dos parâmetros urbanísticos extraídos considerando distintas morfologias urbanas.
Para o nível da usabilidade de nem-se igualmente dois objectivos: i) demonstração
da usabilidade dos parâmetros urbanísticos extraídos avaliando o erro associado a
extracção; ii) demonstração da usabilidade dos parâmetros urbanísticos extraídos
para planeamento, em particular para o mapeamento dasimétrico de alta precisão.
Da investigação decorre uma solução metodol ogica. A solução metodológica
nomeada 3D Extraction Building Parameters (3DEBP) destina-se a extracção da
área, da altura da fachada e do volume dos edifícios a partir de nuvens de pontos
3D. Esta solução foi criada tendo por base um conjunto de ferramentas FOSS:
PostgreSQL/PostGIS, QGIS, GRASS e R-stats.
Foram realizados testes em duas áreas urbanas com morfologias distintas:
Praia de Faro (morfologia irregular) e Amadora (morfologia regular). O teste sobre
a área urbana da Praia de Faro utilizou uma nuvem de pontos LiDAR e uma outra
extra da de levantamento realizado por UAV. O teste sobre um quarteirão urbano
de Amadora foi realizado apenas sobre nuvem de pontos UAV. Os testes revelaram
que a qualidade da informação extra da e dependente da morfologia urbana.
Nas conclusões discute-se a medição 3D com base em dados obtidos por
tecnologia LiDAR e UAV, questiona-se a implementação de soluções FOSS para
diferentes fases do processo de planeamento e defende-se a introdução intensiva da
modelação 3D no plano urbano do futuro.Geographical data plays a major role in urban plan development, both as a planning instrument and as a normative document that legally de nes public obligations and binds individuals, in a given period of time, regarding the urban aspect of a city or an urban conglomerate, and establishes standards for land use and land cover. The plan is associated with a process, called the planning process, which consists in a set of dynamic and adaptive phases that begin with its development and end with the evaluation of any discrepancies between the provisions of the original document and the accomplished goals and objectives. The plan, the process, and the planning praxis require up-to-date geographical data at all times, both for monitoring actions and for the evaluation phases. One of the crucial aspects of the plan is the quanti cation of the existing building volume. Another fundamental aspect is managing that volume: both regarding the existing volume and any additional volumes. Actually, the building volume in built areas has been one of the most sensitive topics on the densi cation of existing urban spaces or the design of new growing urban areas. Considering the existing theoretical framework, the central topic of this thesis focuses on 3D point cloud modelling obtained from LiDAR and UAV technologies, employed in the development of a plan and in the urban planning process, namely regarding two speci c building parameters { building height and volume. The explanation of the central topic of this thesis is twofold: implementation and usability. The implementation level has two goals: i) demonstrating the relevance and pertinence of the extraction, measurement, and 3D geovisualization of building parameters based on the experimentation and implementation of geoprocessing techniques; ii) demonstrating the pertinence of the extracted building parameters considering di erent urban morphologies. At the usability level, we de ned two goals: i) demonstrating the usability of the extracted building parameters, evaluating the error associated with the extraction; ii) demonstrating the usability of these parameters for planning, particularly for high precision dasymetric mapping. Based on our research, we propose a methodological solution termed. 3D Extraction Building Parameters (3DEBP) and aimed at extracting areas, fa cade height, and building volumes from 3D point clouds. This solution was created with the following set of FOSS tools: PostgreSQL/PostGIS, GRASS, QGIS, and R-stats. We performed several tests in two urban areas with di erent morphologies: Praia de Faro (irregular morphology) and Amadora (regular morphology). The former (Praia de Faro) used a LiDAR point cloud and another one extracted from a UAV survey, while the latter (urban neighbourhood of Amadora) only used a UAV point cloud. Both experiments reveal that the quality of the information extracted depends on urban morphology. Finally, we discuss 3D measurement based on data obtained from LiDAR and UAV technology, raising questions on the implementation of FOSS solutions for di erent phases of the planning process, and arguing for the intensive introduction of 3D modelling for the future of urban planning.
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Tsagouri, I., A. Belehaki, N. Bergeot, C. Cid, V. Delouille, T. Egorova, N. Jakowski, et al. "Progress in space weather modeling in an operational environment." 2013. http://hdl.handle.net/10454/9741.
Full textAbstract:
YesThis paper aims at providing an overview of latest advances in space weather modeling in an operational environment in Europe, including both the introduction of new models and improvements to existing codes and algorithms that address the broad range of space weather's prediction requirements from the Sun to the Earth. For each case, we consider the model's input data, the output parameters, products or services, its operational status, and whether it is supported by validation results, in order to build a solid basis for future developments. This work is the output of the Sub Group 1.3 "Improvement of operational models'' of the European Cooperation in Science and Technology (COST) Action ES0803 "Developing Space Weather Products and services in Europe'' and therefore this review focuses on the progress achieved by European research teams involved in the action.