Refractive index discontinuities in fiber optic transmission systems are known to cause deleterious effects. Non-negligible return losses associated with connectors and splices in present day systems cause intermittent error bursts and bit-error-rate floors in gigabit per second systems. These are attributed to the interferometric conversion of laser phase noise into signal-dependent intensity noise. This relative intensity noise (RIN) is substantially higher than the intrinsic RIN of the laser. The power spectral density of the RIN and its impact on the performance of incoherent on-off keying digital systems are calculated. The combined effects of this noise and other degradations present in the system are studied using a simple model. It is shown that even though RIN is a bounded degradation, it, particularly in conjunction with other impairments, results in high and sometimes unacceptable power penalties. Previous analyses are extended to include the effects of multiple reflections from a single pair of reflectors, the effects of a multiplicity of reflection points and the combined effects of reflection-induced noise and other impairments. It is shown that the effect of multiple reflections, although having only a small influence on the reflection induced noise power, changes the distribution of the noise and has more serious system effects. In the case of a multiplicity of reflection points it is shown that for as few as four reflection points, the Gaussian approximation gives results in good agreement with results calculated from a Gram-Charlier series approximation to the actual distribution function. Power penalties as a function of reflection coefficient are calculated and compared using several different approximations for the distribution of the interferometric noise. The methodology presented, although applied specifically to reflection induced noise, is applicable to a broader class of problems in which there are other signal dependent noise phenomena. / Master of Science

No description available.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Techniques for estimating a signal in the presence of noise which contains outliers are currently not well developed. In this thesis, we consider a constant signal superimposed by a family of noise distributions structured as a tunable mixture f(x) = α g(x) + (1 − α) h(x) between finitesupport components of “well-behaved” noise with small variance g(x) and of “impulsive” noise h(x) with a large amplitude and strongly asymmetric character. When α ≈ 1, h(x) can for example model a cosmic ray striking an experimental detector. In the first part of our work, a method for obtaining the expected values of the positive and negative pulses in the first resolution level of a LULU Discrete Pulse Transform (DPT) is established. Subsequent analysis of sequences smoothed by the operators L1U1 or U1L1 of LULU-theory shows that a robust estimator for the location parameter for g is achieved in the sense that the contribution by h to the expected average of the smoothed sequences is suppressed to order (1 − α)2 or higher. In cases where the specific shape of h can be difficult to guess due to the assumed lack of data, it is thus also shown to be of lesser importance. Furthermore, upon smoothing a sequence with L1U1 or U1L1, estimators for the scale parameters of the model distribution become easily available. In the second part of our work, the same problem and data is approached from a Bayesian inference perspective. The Bayesian estimators are found to be optimal in the sense that they make full use of available information in the data. Heuristic comparison shows, however, that Bayes estimators do not always outperform the LULU estimators. Although the Bayesian perspective provides much insight into the logical connections inherent in the problem, its estimators can be difficult to obtain in analytic form and are slow to compute numerically. Suboptimal LULU-estimators are shown to be reasonable practical compromises in practical problems. / AFRIKAANSE OPSOMMING: Tegnieke om ’n sein af te skat in die teenwoordigheid van geraas wat uitskieters bevat is tans nie goed ontwikkel nie. In hierdie tesis aanskou ons ’n konstante sein gesuperponeer met ’n familie van geraasverdelings wat as verstelbare mengsel f(x) = α g(x) + (1 − α) h(x) tussen eindige-uitkomsruimte geraaskomponente g(x) wat “goeie gedrag” en klein variansie toon, plus “impulsiewe” geraas h(x) met groot amplitude en sterk asimmetriese karakter. Wanneer α ≈ 1 kan h(x) byvoorbeeld ’n kosmiese straal wat ’n eksperimentele apparaat tref modelleer. In die eerste gedeelte van ons werk word ’n metode om die verwagtingswaardes van die positiewe en negatiewe pulse in die eerste resolusievlak van ’n LULU Diskrete Pulse Transform (DPT) vasgestel. Die analise van rye verkry deur die inwerking van die gladstrykers L1U1 en U1L1 van die LULU-teorie toon dat hul verwagte gemiddelde waardes as afskatters van die liggingsparameter van g kan dien wat robuus is in die sin dat die bydrae van h tot die gemiddeld van orde grootte (1 − α)2 of hoër is. Die spesifieke vorm van h word dan ook onbelangrik. Daar word verder gewys dat afskatters vir die relevante skaalparameters van die model maklik verkry kan word na gladstryking met die operatore L1U1 of U1L1. In die tweede gedeelte van ons werk word dieselfde probleem en data vanuit ’n Bayesiese inferensie perspektief benader. Die Bayesiese afskatters word as optimaal bevind in die sin dat hulle vol gebruikmaak van die beskikbare inligting in die data. Heuristiese vergelyking wys egter dat Bayesiese afskatters nie altyd beter vaar as die LULU afskatters nie. Alhoewel die Bayesiese sienswyse baie insig in die logiese verbindings van die probleem gee, kan die afskatters moeilik wees om analities af te lei en stadig om numeries te bereken. Suboptimale LULU-beramers word voorgestel as redelike praktiese kompromieë in praktiese probleme.

Trata-se de um estudo quantitativo descritivo, exploratório e observacional cujo objetivo foi determinar os níveis de ruído ambiente na unidade de cuidado intermediário neonatal de um hospital universitário de Ribeirão Preto-SP e dimensionar os níveis de pressão sonora (NPS) gerados em decorrência de ar condicionado, lâmpadas da enfermaria e monitor de apnéia ligados; alarme acionado; torneira da pia aberta; manejo da lixeira; conversas entre profissionais (visita médica e passagem de plantão da enfermagem) e ruídos externos (abrir e fechar a porta de acesso à unidade neonatal e conversação na ante-sala). O ruído ambiente foi dimensionado na enfermaria de manipulação mínima da unidade de cuidado intermediário neonatal, em duas semanas consecutivas, sendo 12 horas por dia no período diurno das 7 às 19 horas na primeira semana e 12 horas no noturno, diariamente das 19 às 7 horas, na segunda semana. Utilizou-se o medidor de NPS, o dosímetro Quest-400, posicionado na área central da enfermaria e suspenso a 70 cm do teto. Para dimensionar cada ruído interno e externo, discriminado no segundo objetivo, mantiveram-se na enfermaria os mesmos bebês ali internados e somente a pesquisadora, evitando-se a presença de outros ruídos audíveis. Mensurou-se os NPS por três minutos consecutivos, exceto a passagem de plantão da enfermagem que incluiu três momentos de medida, sendo uma para cada final de turno de trabalho. Para análise dos dados utilizou-se o programa QuestSuiteMR para processar os NPS em respostas numéricas e transportar em planilhas no software Excel 2003 e SPSS (Statiscal Package for the Social Sciences). O nível médio de ruído na unidade foi de 60,8dBA. A variabilidade do Leq na semana foi de 20,8dBA (51,8 a 72,6dBA), Lpeak 23,6dBA (90,1 a 113,7dBA), Lmax 42,8dBA (52,1 a 90,9dBA) e do Lmin foi de 1,4dBA (50,7 a 52,1dBA). As hipóteses de que mesmo em enfermaria de manipulação mínima o ruído é intenso e que a fonte de ruído mais intensa é o abrir e fechar a tampa da lixeira (Leq médio de 59,3dBA) foram confirmadas. A porta aberta da enfermaria permitiu maior entrada de ruído externo gerado na ante-sala, em especial aquele decorrente de abrir e fechar a porta de correr de acesso à unidade neonatal (57,3dBA). Assim, confirmou-se a terceira hipótese, que o ruído ambiente diminui ao fechar a porta de acesso à enfermaria. Confirmou-se também a quarta hipótese, que a conversa entre os profissionais na passagem de plantão da enfermagem e visita médica constitui fonte de ruído intenso, sendo que os maiores Leq foram de 63,8dBA em ambas situações. Concluiu-se que os NPS foram intensos em todos os turnos e dias da semana da coleta de dados, estando acima das recomendações e normas técnicas para níveis de ruído adequados em unidades neonatais. Com base nos resultados e na literatura elaborou-se um protocolo para controlar o excesso de estímulos sonoros ambientais, incluindo um conjunto de ações intersetoriais dirigidas à infra-estrutura física, aos recursos tecnológicos e humanos (profissionais e familiares). / This descriptive, exploratory and observational quantitative study aimed to determine ambient noise levels at the intermediary neonatal care unit of a university hospital in Ribeirão Preto-SP and dimension sound pressure levels (SPL) produced by air-conditioning, lamps at the nursing ward and the functioning of apnea monitors; alarms going off; open water taps; handling of garbage cans; conversations among professionals (medical visit and nursing shift change) and external noise (opening and closing the access door of the neonatal unit and conversation in the antechamber). Ambient noise was dimensioned at the minimal manipulation nursing ward in the intermediary neonatal care unit of the university hospital in Ribeirão Preto-SP for two consecutive weeks. In the first week, ambient noise levels were measured every day for 12 hours, from 7 a.m. to 7 p.m. In the second, ambient noise was measured every night for 12 hours, from 7 p.m. to 7 a.m. A Quest-400 dosimeter was used to measure SPL, placed in the center of the ward and hung from the roof at 70 cm. To dimension each internal and external noise distinguished in the second objective, only the hospitalized babies and the researcher continued at the ward, avoiding the presence of other audible noise. Sound pressure levels were measured for three consecutive minutes, except during nursing shift changes, including three measurement moments, one at the end of each shift. For data analysis, QuestSuiteMR was used to process SPL in numerical answers and move them to Excel 2003 and SPSS (Statistical Package for the Social Sciences) worksheets. The mean sound level at the unit was 60.8dBA. A variability of 20.8dBA (from 51.8 to 72.6dBA) was found for Leq, 23.6dBA (90.1 to 113.7dBA) for Lpeak, 42.8dBA (52.1 to 90.9dBA) for Lmax and 1.4dBA (50.7 to 52.1dBA) for Lmin. The results confirmed the hypotheses that noise is intense, even at a minimal manipulation ward, and that opening and closing the garbage can is the most intense noise source (mean Leq 59.3dBA). The open door of the nursing ward allowed more external noise from the antechamber to enter, especially noise produced by opening and closing the running door that gave access to the neonatal unit (57.3dBA). This confirmed the third hypothesis, that is, that environmental noise decreases when the door of the nursing ward is closed. The fourth hypothesis was also confirmed, i.e. that conversations between professionals during shift changes and medical visits were a source of intense noise. The highest Leq corresponded to 63.8dBA in both situations. Sound pressure levels were intense across all shifts and days of the data collection period, exceeding recommendations and technical standards for adequate noise levels at neonatal units. Based on these results and on literature, a protocol was elaborated to control the excess of ambient noise stimuli, including a set of intersectorial actions directed at physical infrastructure, technological and human resources (professionals and family members).

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.

Made available in DSpace on 2016-04-27T18:12:01Z (GMT). No. of bitstreams: 1 Aidilma Silva Ferreira.pdf: 1574476 bytes, checksum: 6b240b6332f8c9109f21e4896d438d70 (MD5) Previous issue date: 2013-07-31 / Noise is an important public health problem. Hospitals, that should provide adequate conditions for acoustic comfort to its patients and employees, are not considered quiet environments, which can bring harm to their health. Objective. To verify the newborn assistance health professionals exposure to occupational noise and to investigate their auditory and non-auditory complaints. Method. The sample consisted of 34 nursing technicians and 32 nursing assistants, all female. The age ranged from 24 to 56 years, with a mean of 37.4. The study of the noise perception was performed using a questionnaire. Sound levels were measured by noise dosimetries on employees during their working hours in day and night shifts. Two Wed007 type 2 dosimeters of the 01dB trademark were used. Statistical analysis was performed using chi-square test to assess the relations between the variables. Results. Most professionals considered the environment to be noisy (98.4%) and believed they, somehow, contributed to ambient noise. The main noise sources reported were equipment and monitoring alarms and people talking. The discomfort, stress, fatigue and irritability were complaints that affected the professionals in a greater degree because of the sense of ambient noise. Statistically significant associations (p <0.05) with stress, fatigue and discomfort in individuals who had the perception that the environment was noisy were found. Professionals who felt more stressed because of the environmental noise perception believed that the noise interfered with their work efficiency (p = 0.002) and thinking (p = 0.010), and reported to be very or extremely annoyed by noise (p = 0.000), bad mood (p = 0.000) and irritability (p = 0.000), being harder to understand others speech (p = 0.000). The most common effects were headache and sensitivity to loud noise. LAeq levels ranged from 70.3 dB (A) to 82.5 dB (A). The minimum levels were in the range of 42.3 dB (A) and 55 dB (A). The maximum levels ranged from 81.3 dB (A) to 94.2 dB (A). Conclusions. Sound levels were higher than those recommended by the acoustic comfort standards. Important statistical associations between the noisy environment and the professionals health complaints were found. The noise can affect oral communication aspects and workers task performance / O ruído representa um importante problema de saúde pública. Os hospitais, que deveriam fornecer adequadas condições de conforto acústico aos seus pacientes e funcionários, não são considerados ambientes silenciosos, o que pode trazer prejuízo à saúde destes. Objetivo. Verificar a exposição a ruído ocupacional da equipe de profissionais de saúde que atua em setores de assistência a recém-nascido e investigar suas queixas auditivas e não auditivas. Método. A amostra foi composta por 34 técnicas de enfermagem e 32 auxiliares de enfermagem, todas do sexo feminino. A idade variou de 24 a 56 anos, sendo a média igual a 37,4. O estudo da percepção do ruído foi realizado por meio da aplicação de um questionário. Os níveis sonoros foram medidos por meio de dosimetrias de ruído nos funcionários durante a jornada de trabalho, nos turnos diurno e noturno. Foram utilizados dois dosímetros do tipo 2, modelo Wed007, marca 01dB. A análise estatística foi realizada por meio de teste qui-quadrado, para verificar as associações entre as variáveis de estudo. Resultados. A maioria dos profissionais considerou o ambiente ruidoso (98,4%) e acredita que contribui com o barulho. As principais fontes de ruído relatadas foram os equipamentos e alarmes de monitoramento e as pessoas conversando. O incômodo, o estresse, o cansaço e a irritabilidade foram as queixas que afetaram os profissionais em maior grau devido à sensação do ruído ambiente, sendo encontradas associações estatisticamente significantes (p<0,05) com o estresse, o incômodo e o cansaço em indivíduos que tinham a percepção de que o ambiente é barulhento. Os profissionais que se sentiam mais estressados pela percepção do ruído do ambiente acreditavam que o ruído atrapalhava sua eficiência no trabalho (p=0,002) e o raciocínio (p=0,010), bem como sentiam que o ruído incomodava bastante ou extremamente (p=0,000), causava mau-humor (p=0,000) e irritabilidade (p=0,000), atrapalhando entender a fala dos outros (p=0,000). Os sintomas mais relatados foram cefaleia e incômodo a sons fortes. Os valores de LAeq variaram de 70,3 dB(A) a 82,5 dB(A). Os níveis mínimos se encontravam na faixa entre 42,3 dB(A) e 55 dB(A). Os níveis máximos encontrados variaram de 81,3 dB(A) a 94,2dB(A). Conclusões. Os níveis sonoros encontrados estavam acima dos recomendados pelas normas de conforto acústico. Foram encontradas importantes associações estatísticas entre o ambiente barulhento e queixas de saúde dos profissionais. O ruído pode prejudicar aspectos relacionados à comunicação oral e afetar na execução das atividades destes profissionais

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Paola Crandall Fano. / M.S.

Trata-se de um estudo quantitativo descritivo, exploratório e observacional cujo objetivo foi determinar os níveis de ruído ambiente na unidade de cuidado intermediário neonatal de um hospital universitário de Ribeirão Preto-SP e dimensionar os níveis de pressão sonora (NPS) gerados em decorrência de ar condicionado, lâmpadas da enfermaria e monitor de apnéia ligados; alarme acionado; torneira da pia aberta; manejo da lixeira; conversas entre profissionais (visita médica e passagem de plantão da enfermagem) e ruídos externos (abrir e fechar a porta de acesso à unidade neonatal e conversação na ante-sala). O ruído ambiente foi dimensionado na enfermaria de manipulação mínima da unidade de cuidado intermediário neonatal, em duas semanas consecutivas, sendo 12 horas por dia no período diurno das 7 às 19 horas na primeira semana e 12 horas no noturno, diariamente das 19 às 7 horas, na segunda semana. Utilizou-se o medidor de NPS, o dosímetro Quest-400, posicionado na área central da enfermaria e suspenso a 70 cm do teto. Para dimensionar cada ruído interno e externo, discriminado no segundo objetivo, mantiveram-se na enfermaria os mesmos bebês ali internados e somente a pesquisadora, evitando-se a presença de outros ruídos audíveis. Mensurou-se os NPS por três minutos consecutivos, exceto a passagem de plantão da enfermagem que incluiu três momentos de medida, sendo uma para cada final de turno de trabalho. Para análise dos dados utilizou-se o programa QuestSuiteMR para processar os NPS em respostas numéricas e transportar em planilhas no software Excel 2003 e SPSS (Statiscal Package for the Social Sciences). O nível médio de ruído na unidade foi de 60,8dBA. A variabilidade do Leq na semana foi de 20,8dBA (51,8 a 72,6dBA), Lpeak 23,6dBA (90,1 a 113,7dBA), Lmax 42,8dBA (52,1 a 90,9dBA) e do Lmin foi de 1,4dBA (50,7 a 52,1dBA). As hipóteses de que mesmo em enfermaria de manipulação mínima o ruído é intenso e que a fonte de ruído mais intensa é o abrir e fechar a tampa da lixeira (Leq médio de 59,3dBA) foram confirmadas. A porta aberta da enfermaria permitiu maior entrada de ruído externo gerado na ante-sala, em especial aquele decorrente de abrir e fechar a porta de correr de acesso à unidade neonatal (57,3dBA). Assim, confirmou-se a terceira hipótese, que o ruído ambiente diminui ao fechar a porta de acesso à enfermaria. Confirmou-se também a quarta hipótese, que a conversa entre os profissionais na passagem de plantão da enfermagem e visita médica constitui fonte de ruído intenso, sendo que os maiores Leq foram de 63,8dBA em ambas situações. Concluiu-se que os NPS foram intensos em todos os turnos e dias da semana da coleta de dados, estando acima das recomendações e normas técnicas para níveis de ruído adequados em unidades neonatais. Com base nos resultados e na literatura elaborou-se um protocolo para controlar o excesso de estímulos sonoros ambientais, incluindo um conjunto de ações intersetoriais dirigidas à infra-estrutura física, aos recursos tecnológicos e humanos (profissionais e familiares). / This descriptive, exploratory and observational quantitative study aimed to determine ambient noise levels at the intermediary neonatal care unit of a university hospital in Ribeirão Preto-SP and dimension sound pressure levels (SPL) produced by air-conditioning, lamps at the nursing ward and the functioning of apnea monitors; alarms going off; open water taps; handling of garbage cans; conversations among professionals (medical visit and nursing shift change) and external noise (opening and closing the access door of the neonatal unit and conversation in the antechamber). Ambient noise was dimensioned at the minimal manipulation nursing ward in the intermediary neonatal care unit of the university hospital in Ribeirão Preto-SP for two consecutive weeks. In the first week, ambient noise levels were measured every day for 12 hours, from 7 a.m. to 7 p.m. In the second, ambient noise was measured every night for 12 hours, from 7 p.m. to 7 a.m. A Quest-400 dosimeter was used to measure SPL, placed in the center of the ward and hung from the roof at 70 cm. To dimension each internal and external noise distinguished in the second objective, only the hospitalized babies and the researcher continued at the ward, avoiding the presence of other audible noise. Sound pressure levels were measured for three consecutive minutes, except during nursing shift changes, including three measurement moments, one at the end of each shift. For data analysis, QuestSuiteMR was used to process SPL in numerical answers and move them to Excel 2003 and SPSS (Statistical Package for the Social Sciences) worksheets. The mean sound level at the unit was 60.8dBA. A variability of 20.8dBA (from 51.8 to 72.6dBA) was found for Leq, 23.6dBA (90.1 to 113.7dBA) for Lpeak, 42.8dBA (52.1 to 90.9dBA) for Lmax and 1.4dBA (50.7 to 52.1dBA) for Lmin. The results confirmed the hypotheses that noise is intense, even at a minimal manipulation ward, and that opening and closing the garbage can is the most intense noise source (mean Leq 59.3dBA). The open door of the nursing ward allowed more external noise from the antechamber to enter, especially noise produced by opening and closing the running door that gave access to the neonatal unit (57.3dBA). This confirmed the third hypothesis, that is, that environmental noise decreases when the door of the nursing ward is closed. The fourth hypothesis was also confirmed, i.e. that conversations between professionals during shift changes and medical visits were a source of intense noise. The highest Leq corresponded to 63.8dBA in both situations. Sound pressure levels were intense across all shifts and days of the data collection period, exceeding recommendations and technical standards for adequate noise levels at neonatal units. Based on these results and on literature, a protocol was elaborated to control the excess of ambient noise stimuli, including a set of intersectorial actions directed at physical infrastructure, technological and human resources (professionals and family members).

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First, the concepts of reflection coefficients, s-parameters, Smith chart, noise figure, and available power gain will be introduced. This lays out the foundation for the presentation of techniques on measuring noise figure and gain of high speed bipolar junction transistors. Noise sources in a bipolar junction transistor and an equivalent circuit including these noise sources will be presented. The process of determining the noise parameters of a transistor will also be discussed. A Pascal program and several TEKSPICE scripts are developed to calculate the stability, available power gain, and noise figure circles. Finally, these circles are plotted on a Smith chart to give a clear view of how a transistor will perform due to a change in source impedances.