It is widely acknowledged that bearing failures are the primary reason for breakdowns in rotating machinery. These failures are extremely costly, particularly in terms of lost production. Roller bearings are widely used in industrial machinery and need to be maintained in good condition to ensure the continuing efficiency, effectiveness, and profitability of the production process. The research presented here is an investigation of the use of acoustic emission (AE) to monitor bearing conditions at low speeds. Many machines, particularly large, expensive machines operate at speeds below 100 rpm, and such machines are important to the industry. However, the overwhelming proportion of studies have investigated the use of AE techniques for condition monitoring of higher-speed machines (typically several hundred rpm, or even higher). Few researchers have investigated the application of these techniques to low-speed machines ( < 100 rpm), This PhD addressed this omission and has established which, of the available, AE techniques are suitable for the detection of incipient faults and measurement of fault growth in low-speed bearings. The first objective of this research program was to assess the applicability of AE techniques to monitor low-speed bearings. It was found that the measured statistical parameters successfully monitored bearing conditions at low speeds (10-100 rpm). The second objective was to identify which commonly used statistical parameters derived from the AE signal (RMS, kurtosis, amplitude and counts) could identify the onset of a fault in either race. It was found that the change in AE amplitude and AE RMS could identify the presence of a small fault seeded into either the inner or the outer races. However, the severe attenuation of the signal from the inner race meant that, while AE amplitude and RMS could readily identify the incipient fault, kurtosis and the AE counts could not. Thus, more attention needs to be given to analysing the signal from the inner race. The third objective was to identify a measure that would assess the degree of severity of the fault. However, once the defect was established, it was found that of the parameters used only AE RMS was sensitive to defect size. The fourth objective was to assess whether the AE signal is able to detect defects located at either the centre or edge of the outer race of a bearing rotating at low speeds. It is found that all the measured AE parameters had higher values when the defect was seeded in the middle of the outer race, possibly due to the shorter path traversed by the signal between source and sensor which gave a lower attenuation than when the defect was on the edge of the outer race. Moreover, AE can detect the defect at both locations, which confirmed the applicability of the AE to monitor the defects at any location on the outer race.

It is widely acknowledged that bearing failures are the primary reason for breakdowns in rotating machinery. These failures are extremely costly, particularly in terms of lost production. Roller bearings are widely used in industrial machinery and need to be maintained in good condition to ensure the continuing efficiency, effectiveness, and profitability of the production process. The research presented here is an investigation of the use of acoustic emission (AE) to monitor bearing conditions at low speeds. Many machines, particularly large, expensive machines operate at speeds below 100 rpm, and such machines are important to the industry. However, the overwhelming proportion of studies have investigated the use of AE techniques for condition monitoring of higher-speed machines (typically several hundred rpm, or even higher). Few researchers have investigated the application of these techniques to low-speed machines (<100 rpm), This PhD addressed this omission and has established which, of the available, AE techniques are suitable for the detection of incipient faults and measurement of fault growth in low-speed bearings. The first objective of this research program was to assess the applicability of AE techniques to monitor low-speed bearings. It was found that the measured statistical parameters successfully monitored bearing conditions at low speeds (10-100 rpm). The second objective was to identify which commonly used statistical parameters derived from the AE signal (RMS, kurtosis, amplitude and counts) could identify the onset of a fault in either race. It was found that the change in AE amplitude and AE RMS could identify the presence of a small fault seeded into either the inner or the outer races. However, the severe attenuation of the signal from the inner race meant that, while AE amplitude and RMS could readily identify the incipient fault, kurtosis and the AE counts could not. Thus, more attention needs to be given to analysing the signal from the inner race. The third objective was to identify a measure that would assess the degree of severity of the fault. However, once the defect was established, it was found that of the parameters used only AE RMS was sensitive to defect size. The fourth objective was to assess whether the AE signal is able to detect defects located at either the centre or edge of the outer race of a bearing rotating at low speeds. It is found that all the measured AE parameters had higher values when the defect was seeded in the middle of the outer race, possibly due to the shorter path traversed by the signal between source and sensor which gave a lower attenuation than when the defect was on the edge of the outer race. Moreover, AE can detect the defect at both locations, which confirmed the applicability of the AE to monitor the defects at any location on the outer race.

Made available in DSpace on 2017-07-10T17:31:15Z (GMT). No. of bitstreams: 1 Constantino_Eleutherio_Luz.pdf: 2845155 bytes, checksum: f9e51c3d07bfcebf178a79ea1cc6f916 (MD5) Previous issue date: 2011-11-23 / The dissertation examines the downstream finning phenomenon as it operates in the bottom sediments in the Marrecas river, located in South West region of Parana state, Brazil. The area of basin has 865,43 km2 and encompasses he municipalities of Francisco Beltrão, Marmeleiro, Flor da Serra do Sul, Verê and Itapejara D Oeste. The Marrecas river basin inserted in Cretaceous age rock composed of basaltic rocks of the Serra Geral Formation with plateaus characterized by dissecting medium and high, elongated tops and slopes convex and straight. Were calculated the main basin morphometric index based on 1:260,000 scale map and longitudinal thalweg profile of the main channel based on 1:50,000 scale topographic maps. The botton sediments samples was performed in December 2009 and January 2010 with a van Veen samples in a location preferably located in the vicinity of the main tributaries of Marrecas river and easy access to river banks. The sandy and coarse sediments were analyzed by sieving techniques and use of gravelometer device. Were calculated grain-size statistical parameters: mean, median, sorting, skewness and kurtosis as defined by Folk & Ward (1957). The sphericity of the coarse sediments was defined by adopting the classification of Zingg (1935). The trends observed particle size showed a clear downstream finning of botton sediments in the downstream direction, changed locally due to the contribution of sediments by tributaries. The sorting showed no trend with values ranged from moderately to very poorly. Skewness shows a trend of variation of positive values in the upper reaches of the Marrecas river for negative values in the lower reaches, while the kurtosis showed a slight tendency passing values platikurtic to leptokurtic. The predominance of spherical shape in bottom sediments was attributed to spheroidal weathering and low resistance to abrasion of the rock. / A presente dissertação trata sobre a variação longitudinal das características texturais dos sedimentos de fundo no rio Marrecas, localizado na região Sudoeste do Paraná. A área da bacia do rio Marrecas possui 865,43 km2 e abarca parte dos municípios de Francisco Beltrão, Marmeleiro, Flor da Serra do Sul, Verê e Itapejara D Oeste. O total da bacia do rio Marrecas está inserida em terrenos de idade cretácea formada por rochas basálticas da formação Serra Geral que formam planaltos caracterizados por dissecação média e alta, topos alongados, vertentes convexas e retilíneas. Foram calculados os principais índices morfométricos da bacia baseados em mapas em escala 1:260.000 e elaborado perfil longitudinal do canal principal com base em cartas topográficas em escala 1:50.000. A coleta de sedimentos de fundo foi executada em dezembro de 2009 e janeiro de 2010, com amostrador de mandíbula tipo Van Veen em locais situados preferentemente nas imediações dos principais afluentes do rio Marrecas e em trechos de acesso fácil às margens do rio. Os sedimentos arenosos e rudáceos foram analisados mediante técnicas de peneiramento e emprego de cascalhômetro. Foram calculados os seguintes parâmetros estatísticos: diâmetro médio, mediana, grau de seleção, assimetria e curtose segundo a definição de Folk & Ward (1957). A esfericidade dos sedimentos rudáceos foi definida adotando a classificação de Zingg (1935). As tendências granulométricas observadas mostraram uma nítida granodecrescência dos sedimentos de fundo em direção à jusante, alterada localmente devido ao aporte de sedimentos pelos afluentes. O grau de seleção não mostrou nenhuma tendência e variou de moderadamente a muito pobremente selecionado. A assimetria mostra uma tendência de variação de valores positivos nos trechos superiores do rio Marrecas para valores negativos nos trechos inferiores, enquanto que a curtose exibiu uma passagem de valores platicúrticos para leptocúrticos em direção à jusante. O predomínio da forma esférica nos sedimentos de fundo foi atribuído a decomposição esferoidal do basalto e a baixa resistência desta rocha à abrasão.

Made available in DSpace on 2017-05-12T14:42:47Z (GMT). No. of bitstreams: 1 Constantino_Eleutherio_Luz.pdf: 2845155 bytes, checksum: f9e51c3d07bfcebf178a79ea1cc6f916 (MD5) Previous issue date: 2011-11-23 / The dissertation examines the downstream finning phenomenon as it operates in the bottom sediments in the Marrecas river, located in South West region of Parana state, Brazil. The area of basin has 865,43 km2 and encompasses he municipalities of Francisco Beltrão, Marmeleiro, Flor da Serra do Sul, Verê and Itapejara D Oeste. The Marrecas river basin inserted in Cretaceous age rock composed of basaltic rocks of the Serra Geral Formation with plateaus characterized by dissecting medium and high, elongated tops and slopes convex and straight. Were calculated the main basin morphometric index based on 1:260,000 scale map and longitudinal thalweg profile of the main channel based on 1:50,000 scale topographic maps. The botton sediments samples was performed in December 2009 and January 2010 with a van Veen samples in a location preferably located in the vicinity of the main tributaries of Marrecas river and easy access to river banks. The sandy and coarse sediments were analyzed by sieving techniques and use of gravelometer device. Were calculated grain-size statistical parameters: mean, median, sorting, skewness and kurtosis as defined by Folk & Ward (1957). The sphericity of the coarse sediments was defined by adopting the classification of Zingg (1935). The trends observed particle size showed a clear downstream finning of botton sediments in the downstream direction, changed locally due to the contribution of sediments by tributaries. The sorting showed no trend with values ranged from moderately to very poorly. Skewness shows a trend of variation of positive values in the upper reaches of the Marrecas river for negative values in the lower reaches, while the kurtosis showed a slight tendency passing values platikurtic to leptokurtic. The predominance of spherical shape in bottom sediments was attributed to spheroidal weathering and low resistance to abrasion of the rock. / A presente dissertação trata sobre a variação longitudinal das características texturais dos sedimentos de fundo no rio Marrecas, localizado na região Sudoeste do Paraná. A área da bacia do rio Marrecas possui 865,43 km2 e abarca parte dos municípios de Francisco Beltrão, Marmeleiro, Flor da Serra do Sul, Verê e Itapejara D Oeste. O total da bacia do rio Marrecas está inserida em terrenos de idade cretácea formada por rochas basálticas da formação Serra Geral que formam planaltos caracterizados por dissecação média e alta, topos alongados, vertentes convexas e retilíneas. Foram calculados os principais índices morfométricos da bacia baseados em mapas em escala 1:260.000 e elaborado perfil longitudinal do canal principal com base em cartas topográficas em escala 1:50.000. A coleta de sedimentos de fundo foi executada em dezembro de 2009 e janeiro de 2010, com amostrador de mandíbula tipo Van Veen em locais situados preferentemente nas imediações dos principais afluentes do rio Marrecas e em trechos de acesso fácil às margens do rio. Os sedimentos arenosos e rudáceos foram analisados mediante técnicas de peneiramento e emprego de cascalhômetro. Foram calculados os seguintes parâmetros estatísticos: diâmetro médio, mediana, grau de seleção, assimetria e curtose segundo a definição de Folk & Ward (1957). A esfericidade dos sedimentos rudáceos foi definida adotando a classificação de Zingg (1935). As tendências granulométricas observadas mostraram uma nítida granodecrescência dos sedimentos de fundo em direção à jusante, alterada localmente devido ao aporte de sedimentos pelos afluentes. O grau de seleção não mostrou nenhuma tendência e variou de moderadamente a muito pobremente selecionado. A assimetria mostra uma tendência de variação de valores positivos nos trechos superiores do rio Marrecas para valores negativos nos trechos inferiores, enquanto que a curtose exibiu uma passagem de valores platicúrticos para leptocúrticos em direção à jusante. O predomínio da forma esférica nos sedimentos de fundo foi atribuído a decomposição esferoidal do basalto e a baixa resistência desta rocha à abrasão.

The Brazilian technician-scientific community that dedicates to the surveying is living a new time with the normatization of the technical parameters for reference of the geodesic surveys to Cadastro Nacional de Imóveis Rurais according to Brazilian Law 10.267/2001. The objective of this work is to analyse by means of the statistical parameters the quality of the survey data with GPS-receivers and post-processed in the softwares present in the market. Amongst the analysed parameters, the most important is the standard deviation of the coordinates, because it is the measure for the precision and it is an composition element of the accuracy, that indicate the result quality. The results presented by commercial softwares are compared with the official data of the State Landmark GPS network that are information supplied for the Instituto Brasileiro de Geografia e Estatística (IBGE). Also this work contribute for the relation user-manufacturer approaching them thus first when manipulating the programs get greater information availability how much to the applied methodology to give the processing results. By means of the fundamental univariate and multivariate Statistic concepts, this work give an analysis of as the commercial softwares are processing GPS data and also inform which the necessary minimum data that the softwares must supply to the user in order to give the estimated statistical parameters that are an indication the quality of each geodetic survey. / A comunidade técnico-científica brasileira que se dedica à mensuração está vivendo uma nova época com a normatização de parâmetros técnicos para levantamentos geodésicos destinados ao Cadastro Nacional de Imóveis Rurais de acordo com a Lei 10.267/2001. O objetivo desta dissertação é analisar por meio de parâmetros estatísticos estimados a qualidade dos dados oriundos de levantamentos com receptores GPS e pós-processados em programas computacionais presentes no mercado. Dentre os parâmetros estatísticos analisados, o mais importante é o desvio padrão das coordenadas, porque ele é a medida da precisão e compõe a medida da acurácia que exprimem a qualidade dos resultados. Os resultados apresentados pelos programas comerciais são comparados com dados oficiais da Rede Estadual de Marcos GPS que são informações fornecidas pelo Instituto Brasileiro de Geografia e Estatística (IBGE). Este trabalho também contribui para a relação usuário-fabricante aproximando-os, entre si, de maneira que o primeiro ao manipular os programas obtenha maior disponibilidade de informações quanto à metodologia aplicada para obter os resultados do processamento. Por meio dos conceitos fundamentais da Estatística univariada e multivariada, este trabalho fornece uma análise de como os programas comerciais estão processando os dados GPS e informa, também, quais os dados mínimos necessários que os programas computacionais devem fornecer ao usuário para que este obtenha os parâmetros estatísticos estimados indicadores da qualidade para cada levantamento geodésico.

Abstract This dissertation presents complete parameterizations for a three-dimensional (3-D) geometry-based stochastic radio channel model (GSCM) at 10 GHz based on measurement campaigns. The thesis is divided into the following main parts: radio channel measurements, the characterization of model parameters, and model validation. Experimental multiple-input multiple-output (MIMO) channel measurements carried out in two-story lobby and urban small cell scenarios are first described. The measurements were performed with a vector network analyzer and dual polarized virtual antenna arrays with a bandwidth over 500 MHz. The measurement data was post-processed using the ESPRIT algorithm and the post-processed data was verified using a semi-deterministic map-based model. The results showed a good match between estimated and modeled multipath components (MPCs). In addition, single-input single-output outdoor-to-indoor measurements were executed through a standard multi-pane glass window and concrete wall. A statistical analysis was carried out for defining full 3-D characterization of the propagation channel in both line-of-sight (LOS) and non-line-of-sight (NLOS) propagation conditions. The delay and angular dispersions of MPCs are smaller in comparison to lower frequency bands due to the higher attenuation of the delayed MPCs. Moreover, specular reflection is observed to be the more dominant propagation mechanism in comparison to diffuse scattering, leading to smaller cluster angle spreads in comparison to lower frequency bands. The penetration loss caused by a standard multi-pane glass window is on the same level as in the lower frequency bands, whereas the loss caused by the concrete wall is a few dBs higher than at lower frequency bands. Finally, the GSCM with determined parameters is validated. A MIMO channel was reconstructed by embedding 3-D radiation patterns of the antennas into the propagation path estimates. Equivalently the channel simulations were performed with a quasi deterministic radio channel generator (QuaDRiGa) using the defined parameters. The channel capacity, Demmel condition number, and relative condition numbers are used as the comparison metrics between reconstructed and modeled channels. The results show that the reconstructed MIMO channel matches the simulated MIMO channel well. / Tiivistelmä Tämä väitöskirja esittää parametroinnit kolmiulotteiselle geometriaan perustuvalle stokastiselle radiokanavamallille 10 GHz:n taajuusalueella perustuen mitattuun radiokanavaan. Väitöskirja koostuu kolmesta pääalueesta: radiokanavamittaukset, radiokanavamallin parametrien määrittäminen ja mallin validointi. Aluksi kuvataan kaksikerroksisessa aula ja kaupunkipiensolu ympäristöissä monilähetin monivastaanotin (MIMO) järjestelmällä tehdyt kanavamittaukset. Mittaukset tehtiin vektoripiirianalysaattorilla ja kaksoispolaroiduilla virtuaaliantenniryhmillä 500 MHz kaistanleveydellä. Mittausdata jälkikäsiteltiin käyttämällä ESPRIT-algoritmia ja jälkikäsitelty data varmennettiin osittain deterministisellä mittausympäristön karttaan pohjautuvalla radiokanavamallilla. Tulokset osoittivat hyvän yhteensopivuuden mitattujen ja mallinnettujen moniteiden välillä. Lisäksi toteuttiin yksi-lähetin yksi-vastaanotin mittaukset ulko-sisä etenemisympäristössä monikerroksisen lasin ja betoniseinän läpi. Tilastollinen analyysin avulla määritettiin täysi kolmiulotteinen kuvaus radioaallon etenemiskanavasta näköyhteys ja näköyhteydettömässä tilanteissa. Moniteiden suuremmista vaimennuksista johtuen viive ja kulmahajonnat ovat pienemmät verrattaessa matalempiin taajuuksiin. Peiliheijastus on diffuusisirontaa merkittävämpi radioaallon etenemismekanismi johtaen pienempiin klustereiden kulmahajeisiin matalempiin taajuuksiin verrattuna. Monikerroksisen lasin läpäisyvaimennus on samankaltainen kuin alemmilla taajuuksilla, kun sitä vastoin betoniseinän vaimennus on muutaman desibelin suurempi kuin alemmilla taajuuksilla. Lopulta geometriaan perustava stokastinen radiokanavamalli validoidaan määritellyillä parametreilla. MIMO kanava uudelleen rakennetaan lisäämällä kolmiulotteiset antennien säteilykuviot estimoituihin radioaallon etenemisteihin. Vastaavasti radiokanava simuloidaan näennäisesti deterministisellä radiokanavageneraattorilla (QuaDRiGa) käyttäen määriteltyjä mallin parametreja. Kanavakapasiteettia, Demmel ehtolukua ja suhteellista ehtolukua käytetään vertailumittareina uudelleen rakennetun ja simuloidun kanavan välillä. Tulosten perusteella uudelleen rakennettu MIMO kanava on yhteensopiva simuloidun radiokanavan kanssa.