Measuring the farfield noise levels of full-scale rotor systems is not trivial and can be costly. Researchers prefer to perform small-scale experiments in the laboratory so that they can extrapolate the model scaled results to the larger scale. Typically Inverse Square Law (ISL) is used to extrapolate the sound pressure levels (SPL), obtained from model-scale experiments at relatively small distances to predict noise at much larger distances for larger scale systems. The assumption underlying this extrapolation is that the source itself can be treated as a point sound source. At what distance from a rotor system it can be treated as a point source has never been established. Likewise, many theoretical models of shielding by hard surfaces assume the source to be a point monopole source. If one is interested in shielding the noise of a rotor system by interposing a hard surface between the rotor and the observer, can the rotor system really be considered to be a monopole? If rotating noise sources are under consideration what is the effect of configuration and design parameters? Exploring the validity of point source assumption alluded to above for a rotor for farfield acoustic measurements with and without shielding form the backbone of the present work.

In this research, corrosion behaviour of A36 carbon steel under engineered disbonded coating was investigated in sulphuric acid solutions containing sodium chloride and iron (III) sulphate. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) analyses were carried out to study the morphology and phase composition of corrosion products formed on the carbon steel surface. The results of the SEM analysis showed that only general and pitting corrosion occurred on the carbon steel surface with the engineered crevice. The size of the pits increased as the sulphuric acid and sodium chloride concentrations increased. Moreover, the corrosion products had an open, irregular and loose structure at the pits mouth. The loose and open structure of the corrosion products facilitates diffusion of chloride ions, oxygen, water and contaminants into the carbon steel surface. In contrast, the corrosion products had a very compact and continuous structure outside the pits which provided a good protection against further corrosion. The x-ray diffraction analysis showed that the corrosion products layer mainly consisted of lepidocrocite (γ-FeOOH), goethite (α-FeOOH) and iron sulphide (FeS) on the crevice edges. The Pourbaix diagram of iron in sulphuric acid solution at room temperature indicates that iron sulphide is formed on the metal surface at different pH values. The akaganeite (β-FeOOH) diffraction peak was not identified in any spectrum which could be due to the low concentration of chloride ions in the solutions. Furthermore, the number of lepidocrocite peaks decreased as the sulphuric acid concentration increased from 10 g l-1 to 50 g l-1. The lepidocrocite is dissolved in the presence of sulphuric acid, and the dissolved ion acts as an oxidant to the metal and hence lower lepidocrocite peaks are identified. Electrochemical noise measurement (ECN) testing was also performed to investigate the corrosion process occurring on the carbon steel surface with the engineered crevice. The results of the ECN measurements showed that current increased during first few minutes and then decreased slightly. Also, the coupled potential did not change after an initial shift in negative direction. The low current flowing through the carbon steel electrodes and the constant potential showed that the crevice corrosion did not develop. These results imply that the crevice corrosion may not occur on the carbon steel surface in acidic solutions containing chloride ions.

No description available.

No description available.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The objective of the thesis is the development of a phase noise measuring system that makes use of crosscorrelation and averaging to measure below the system hardware noise floor. Various phase noise measurement techniques are considered after which the phase demodulation method is chosen to be implemented. The full development cycle of the hardware is discussed, as well as the post processing that is performed on the measured phase noise. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is die ontwikkeling van ’n faseruis meetstelsel wat gebruik maak van kruiskorrelasie en vergemiddeling om onder die ruisvloer van die meetstelsel se hardeware te meet. Verskeie faseruis meettegnieke word ondersoek en die fase demodulasie metode word gekies om geïmplementeer te word. Die volle ontwikkelingsiklus van die hardeware word bespreek, sowel as die naverwerking wat toegepas is op die gemete faseruis.

The aim of the work is to determine the noise pollution of the weekend house area around Dehtář. Receiver locations were chosen to find out noise levels in places with the highest intensity of human activity and at each observed source of noise. Noise levels were recorded in four seasons of the year. The equivalent continuous sound pressure levels were quantified. and compared with local noise law limits.

Orientador: Stelamaris Rolla Bertoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-11T19:33:52Z (GMT). No. of bitstreams: 1 Santos_DulceClaudiaJoseViana_M.pdf: 1865213 bytes, checksum: dd7cd6494e4bd0ee9f87996a87c4893d (MD5) Previous issue date: 2004 / Resumo: O ruído aparece como um dos problemas ambientais mais freqüentes nos grandes centros urbanos. As atividades ruidosas estão atingindo também as cidades menores do interior do Estado de São Paulo. Nessas cidades nem sempre existem legislações específicas relacionadas a ruído ou condições técnicas para o controle das fontes ruidosas. Nos casos mais graves as reclamações por incômodo devido a ruído chegam a via judiciária onde um perito é designado para fazer a avaliação do ruído ambiental baseado na norma NBR 10151-Avaliação do ruído em áreas habitadas, visando o conforto da comunidade. Nesse trabalho o enfoque de ruído ambiental é analisado através do levantamento dos incômodos gerados por fontes sonoras fixas em dezesseis cidades da região da Equipe de Perícias de São João da Boa Vista. As fontes sonoras são identificadas, mensuradas e catalogadas como aceitáveis ou não de acordo com o nível de critério de avaliação da norma NBR 10151. Paralelamente foi levantado junto aos municípios a existência de legislações municipais específicas sobre ruído ambiental e pessoal técnico para avaliação. Os resultados obtidos nesse trabalho indicaram como está sendo tratada a poluição sonora nessas cidades e quais as principais fontes sonoras de incômodo. Verificou-se também que os critérios de avaliação dos ruídos propostos pela Norma são adequados a esses municípios. O trabalho sugere pontos importantes para estabelecimento de uma legislação e procedimentos específicos relativos a ruído para esses municípios. / Abstract: The noise is shown as the most frequent environmental problem in big cities. The noisy activities are getting also in small cities of São Paulo State. In these cities, not always there is a specific legislation about noise or technical conditions of noisy sources control. In the most serious case, the reclamation for annoyance due the noise, gets, at the judicial mean, where an expert is designated to do the evaluation of the environmental noise based in the NBR 10.151 rule- Evaluation of the noise in inhabit areas, aiming the confort of the community. In this paper the main point of the environmental noise is analysed through the survey of the annoyances generated by fixul noise sources into sixteen cities from the region of São João da Boa Vista Criminal Expert team. The noise sources are identified, measured and catalogue as acceptable or not in accordance to the level of the criterious of evaluation of NBR 10.151 rule. Paralled was raised with the cities the existence of specific municipal legislation about environmental noise and technicals staff (personal) for evaluation. The results obtained in this work indicated how is being treated the noise pollution in these cities and what the major noise source of annoyance is. It had verified if the criterion of evaluation propose by the rule is adequated in the cities. The work suggests important points for the establishment of a specific legislation and special procedures to these municipalities. / Mestrado / Edificações / Mestre em Engenharia Civil

Introdução. Pensar nos efeitos nocivos do ruído aos recém-nascidos (RN) com saúde debilitada se torna cada vez mais necessário devido aos avanços tecnológicos, ao aumento da sobrevida dos RNs de baixo peso, com maiores períodos de hospitalização. Objetivo geral. Avaliar os níveis de ruído das incubadoras das unidades neonatais de um hospital universitário de Ribeirão Preto, SP, em situações experimentais de manejo. Método. Trata-se de estudo quantitativo do tipo quase-experimental, realizado com 20 incubadoras das unidades neonatais de um hospital universitário de Ribeirão Preto, SP, que se encontravam disponíveis durante o período de coleta de dados. O período de coleta foi de agosto a setembro de 2008. As incubadoras foram divididas em três grupos (1, 2, 3), conforme a marca, o modelo, tempo de uso e situação de manejo. As medidas foram realizadas sem a presença do RN, em uma sala afastada do fluxo rotineiro das unidades neonatais. Foi utilizado um dosímetro, modelo Quest 400, com o microfone fixado dentro da incubadora para mensurar o Nível de Pressão Sonora (NPS). Foram realizadas as mensurações dos níveis de ruído contínuo (funcionamento do motor, alarme soando, pulso oxímetro e bomba de infusão sobre a cúpula e seus alarmes) e de impacto (manipulação da portinhola e ato de colocar o frasco de álcool gel sobre a cúpula) nas incubadoras. Os ruídos de impacto foram analisados nos modos de manipulação cuidadoso e brusco. As medidas com o pulso oxímetro, bomba de infusão e o ato de colocar o frasco de álcool gel sobre a cúpula foram repetidas com a presença do cueiro sobre a cúpula da incubadora. Os valores mensurados de Leq, Lmax, Lmin dos ruídos contínuos e os valores de Lpeak dos ruídos de impacto foram analisados por meio dos valores medianos, mínimos e máximos. Resultados. Os valores medianos gerais dos três grupos encontrados para ruído contínuos foram: Leq de 55,2dBA para ruído de funcionamento das incubadoras; Leq 65,5dBA de para alarme da incubadora; para pulso oxímetro e alarme e bomba de infusão e seu alarme os Leq foram: 54,7dBA, 58,4dBA, 53,9dBA e 66,1dBA NPS, respectivamente. Com cueiro, os valores nessas situações foram: 54,0dBA, 57,8dBA, 55,1dBA e 61,7dBA NPS, respectivamente. Todos Lmax medianos de cada grupo nas situações anteriormente descritas estiveram acima de 65dBA e os Lmin acima de 47dBA. Os ruídos de manipulação alcançaram valores de Lpeak medianos gerais para os três grupos de 91,2dBA e 97,9dBA NPS para abrir a portinhola nos modos cuidadoso e brusco e 91,5dBA e 109,5dBA NPS ao fechar cuidadoso e brusco a portinhola, respectivamente. Os níveis atingidos ao colocar o álcool gel sobre a cúpula no modo cuidadoso com e sem cueiro variaram de 89dBA a 89,6dBA NPS e no modo brusco com e sem cueiro de 107dBA a 107,7dBA. Conclusão. Os níveis gerados pelas incubadoras e seus alarmes estão abaixo daquele recomendado pelas normas nacionais, mas acima da norma internacional. A presença de equipamentos sobre a cúpula e seus alarmes soando não intensificaram os níveis de ruído nas incubadoras, com exceção do alarme da bomba de infusão. Os níveis de ruído produzidos pela manipulação da incubadora e o ato de colocar o álcool gel sobre a cúpula foram intensos e o modo cuidadoso foi um recurso para diminuir os níveis sonoros. De um modo geral, o uso do cueiro não reduziu o ruído gerado pelos equipamentos sobre a cúpula e nem o ruído gerado pelo ato de colocar o álcool gel sobre a cúpula. / Introduction. Technological advances and increase in survivorship of low birth weight newborns (NB), with longer periods of hospitalization, make each time more necessary to think about the noxious effects of noise to NB with weak health. Objective. to evaluate levels of noise in incubators of neonatal units in experimental handling situations, in a university hospital in Ribeirão Preto, state of São Paulo, Brazil. Method. Quantitative quasiexperimental study, carried out in 20 incubators in neonatal units during the data collection period, from August to September 2008, in a university-hospital in Ribeirão Preto, SP. Incubators were divided into three groups (1,2,3), according to brand, model, usage time and handling situation. Measuring occurred when NB were not in incubators, in a room far from usual neonatal unit routine work. A Quest 400 dosimeter with microphone fixed inside incubator was used to measure Sound Pressure Level (SPL). Levels of continuous noise (motors functioning, alarm sound, pulse oximeter and infusion bombs on the incubator dome and their alarms) and impact noise (manipulation of incubators door and putting the bottle of alcohol gel on the dome) in incubators were measured. Impact noises were analyzed for careful and rough manipulation. Measures with pulse oximeter, infusion bomb and putting the bottle of alcohol gel on the incubator dome were repeated with a swathe placed on the dome. Continuous noise Leq, Lmax, Lmin and impact noise Lpeak values measured were analyzed using mean, minimum and maximum values. Results. General mean values found for continuous noise in the three groups were: Leq intensity of 55,2dBA for incubators functioning noise; Leq 65,5dBA for incubators alarm; for pulse oximeter, alarm, infusion bomb and infusion bombs alarm Leq were: 54,7dBA, 58,4dBA, 53,9dBA and 66,1dBA SPL, respectively. Using a swathe, values in the same situations were: 54,0dBA, 57,8dBA, 55,1dBA and 61,7dBA SPL respectively. All mean Lmax for each group in the previously described situations were over 65dBA and Lmin over 47dBA. Manipulation noises reached Lpeak general mean values for the three groups of 91,2dBA and 97,9dBA SPL for rough and careful opening of incubator door, and 91,5dBA and 109,5dBA SPL for careful and rough closing, respectively. Levels reached for putting alcohol gel on the incubator dome carefully, with or without swathe, varied from 89dBC to 89,6dBC SPL, and roughly, with or without swathe, varied from 107dBC to 107,7dBC. Conclusion. Noise levels generated by incubators and alarms are under national rules, but over international rules. The presence of equipments on the dome and the sound of incubator alarm do not increase the levels of noise in incubators, with exception of infusion bombs alarm. Noise levels produced by incubator manipulation and putting alcohol gel on the incubator dome are intense, careful mode was a way to decrease noise levels. In a general way, the use of a swathe did not reduce noise generated by the equipments on the dome neither noise of putting alcohol gel on the dome.

Orientador: Antonieta Keiko Kakuda Shimo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-18T15:10:56Z (GMT). No. of bitstreams: 1 Sanfelice_ClaraFroesdeOliveira_M.pdf: 2441381 bytes, checksum: 28198db5d3bb9994aa4ed11dccb9420a (MD5) Previous issue date: 2011 / Resumo: Objetivo: Avaliar o nível de ruído em sala de parto durante o processo de nascimento em duas maternidades públicas do interior do Estado de São Paulo, sendo uma com atividades de ensino (H1), segundo o tipo de parto. Metodologia:Trata-se de um estudo exploratório, descritivo e observacional. Utilizou-se o decibelímetro para registrar os níveis de pressão sonora em decibéis (dB) que permaneceu ligado durante o momento do parto e também um formulário do tipo checklist para anotação de variáveis (tempo de duração, número de pessoas em sala, valor máximo, médio e mínimo do ruído). A coleta de dados segue as normas da NBR 10-151 e foi realizada de agosto de 2010 a janeiro de 2011. O tamanho amostral foi constituído de 34 partos para o H1 e 45 para o H2. Utilizou-se o teste de Kolmogorv-Smiinov para avaliar a aderência das variáveis à distribuição normal. Os níveis de ruídos foram comparados segundo o hospital, utilizando-se o teste de Mann-Whiteney, e o tipo de parto, empregando-se o teste de Kruskal-Wallis. Resultados: O nível de ruído médio global foi de 64dB; sendo 61,2dB para o H1 e 65,3dB para o H2. O parto vaginal sem analgesia obteve ruído médio de 66,9dB, seguindo-se de 63dB para o parto vaginal com analgesia e 61,8dB para a cesárea. O número de pessoas em sala foi superior no hospital de ensino (p=0,0008) e para o parto cesáreo (p=<0,0001). Conclusão: o nível de ruído médio global foi de 64dB, superior a todos valores recomendados pelas normas regulamentadoras atuais, nacionais e internacionais, em ambas as instituições e para todos os tipos de parto, representando um fator preocupante para todos profissionais envolvidos diretamente à assistência ao parto / Abstract: Objective: To assess the noise level in the delivery room during the birth process in two public hospitals in the state of Sao Paulo, one of them a teaching hospital (H1), considering the type of delivery. Methodology: This is exploratory, descriptive and observational. We used a decibel meter to record the sound pressure in decibels(dB) that remained on during the time of delivery and also form a kind of check list for an notation variables (duration, number of people in the room, maximum, average and minimum noise). Data collection follows the standards of ISO10-151 and was conducted from august 2010 to January 2011. We used the test-Kolmogorv Smiinov to asses adherence to the normal distribution of variables. The noise levels were compared according to the hospital using the Mann-Whiteney and compared according to type of delivery employing the Kruskal-Wallis. Results: The average overall noise level was 64 dB, from 61.2 dB to 65.3 dB for H1 and H2. A vaginal delivery without analgesia had average noise of 66.9 dB, followed by a 63 dB for vaginal delivery with analgesia and 61.8 dB for CS. The number of people in the room was higher in the teaching hospital (p=0,0008) and cesarean delivery (p=<0,0001). Conclusion: The average overall was 64 dB, superior to all recommended values by current regulatory standards, national and international in both institutions and all types of current delivery, representing a concern for all professionals directly involved in maternity care / Mestrado / Enfermagem e Trabalho / Mestre em Enfermagem

No description available.