Orientador: Kléber Pereira Lanças / Banca: Carlos Antonio Gamero / Banca: Tomaz Caetano Ripoli / Banca: Luiz Malcolm Mano de Mello / Banca: Paulo Sérgio G. Magalhães / Resumo: Com o aumento da potência de seus motores, visando um melhor desempenho operacional, os tratores agrícolas tiveram um significativo acréscimo nos seus níveis de ruído, colocando os tratoristas entre os profissionais de maior porcentagem de perda de audição. Neste trabalho, objetivou-se quantificar os problemas ocupacionais da relação trator-operador, relacionados ao ruído. Assim, a presente análise divide-se em duas partes: um amplo levantamento dos níveis de ruído de tratores agrícolas de fabricação nacional, medidos em condições reais de trabalho no campo, e uma avaliação audiométrica em tratoristas. Essa divisão foi necessária, pois, embora apontem para a mesma conclusão final, as duas análises pertencem a áreas totalmente diversas, usam metodologias próprias, equipamentos de medida distintos e processos de medição diferentes. Como conclusão final, pode-se afirmar que existe um grave problema ocupacional na operação dos tratores nacionais, em razão dos altos níveis de ruído, expondo os operadores dessas máquinas a grandes riscos de perda de audição. / Abstract: In the last years, the agricultural tractors engine, were increased your power, inducing a hearing loss your operators. In this work, the occupational problems of relations tractor-operator is analysed. This analysis is divided in two parts: the tractors noise level measurement, in real conditions at agricultural work; and analysis of auditive since thought both research indicating, for the some final conclusions, they are of distinct areas. The results of measurements presents very high noise level. / Doutor

Made available in DSpace on 2014-06-11T19:31:37Z (GMT). No. of bitstreams: 0 Previous issue date: 1991-12-02Bitstream added on 2014-06-13T20:02:29Z : No. of bitstreams: 1 fernandes_jc_dr_botfca.pdf: 2492287 bytes, checksum: a807c8c30ec8482500cef1854cdf2cb1 (MD5) / Com o aumento da potência de seus motores, visando um melhor desempenho operacional, os tratores agrícolas tiveram um significativo acréscimo nos seus níveis de ruído, colocando os tratoristas entre os profissionais de maior porcentagem de perda de audição. Neste trabalho, objetivou-se quantificar os problemas ocupacionais da relação trator-operador, relacionados ao ruído. Assim, a presente análise divide-se em duas partes: um amplo levantamento dos níveis de ruído de tratores agrícolas de fabricação nacional, medidos em condições reais de trabalho no campo, e uma avaliação audiométrica em tratoristas. Essa divisão foi necessária, pois, embora apontem para a mesma conclusão final, as duas análises pertencem a áreas totalmente diversas, usam metodologias próprias, equipamentos de medida distintos e processos de medição diferentes. Como conclusão final, pode-se afirmar que existe um grave problema ocupacional na operação dos tratores nacionais, em razão dos altos níveis de ruído, expondo os operadores dessas máquinas a grandes riscos de perda de audição. / In the last years, the agricultural tractors engine, were increased your power, inducing a hearing loss your operators. In this work, the occupational problems of relations tractor-operator is analysed. This analysis is divided in two parts: the tractors noise level measurement, in real conditions at agricultural work; and analysis of auditive since thought both research indicating, for the some final conclusions, they are of distinct areas. The results of measurements presents very high noise level.

Abstract : This thesis considers the discrimination of inlet / exhaust noise of aero-engines in free-field static tests using far-field microphone arrays. Various techniques are compared for this problem, including classical beamforming (CB), regularized inverse method (Tikhonov regularization), LI - generalized inverse beamforming (LI-GIB), clean-PSF, clean-SC and two novel methods which are called hybrid method and clean-hybrid. The classical beamforming method is disadvantaged due to its need for a high number of measurement microphones in accordance with the requirements. Similarly, the inverse method is disadvantaged due to their need of having a priori source information. The classical Tikhonov regularization provides improvements in solution stability, however continues to be disadvantaged due to its requirement of imposing a stronger penalty for undetected source positions. Coherent and incoherent sources are resolved by LI-generalized inverse beamforming (L1-GIB). This algorithm can distinguish the multipole sources as well as the monopoles sources. However, source identification by LI-generalized inverse beamforming takes much time and requires a PC with high memory. The hybrid method is a new regularization method which involves the use of an a priori beamforming measurement to define a data-dependent discrete smoothing norm for the regularization of the inverse problem. Compared to the classical beamforming and the inverse modeling, the hybrid (beamforming regularization) approach provides improved source strength maps without substantial added complexity. Although the hybrid method rather solves the disadvantage of the former methods, the application of this method for identification of weaker sources in the presence of the strong sources isn't satisfactory. This can be explained by the large penalization being applied to the weaker source in the hybrid method, which results in underestimation of source strength for this source. To overcome this defect, the clean-SC method and the proposed clean-hybrid method, which is a combination of the hybrid method and the clean-SC, are applied. These methods remove the effect of the strong sources in source power maps to identify the weaker sources. The proposed methods which represent the main contribution of this thesis show promising results and opens new research avenues. Theoretical study of all approaches is performed for various sources and configurations of array. In order to validate the theoretical study, several laboratory experiments are conducted at Universito de Sherbrooke. The proposed methods have further been applied to the measured noise data from a Pratt & Whitney Canada turbo-fan engine and have been observed to provide better spatial resolution and solution robustness with a limited number of measurement microphones compared to the existing methods. / Résumé : La présente thèse étudie la discrimination du bruit d'entrée / de sortie des moteurs d'avion dans des tests statiques en champ libre en utilisant des antennes de microphones en champ lointain. Diverses techniques sont comparées pour ce problème, dont la formation de voie classique (CB), la méthode inverse régularisée (régularisation de Tikhonov), la formation de voies généralisée inverse (L1-GIB), Clean-PSF, Clean-SC et deux méthodes proposées qui s'appellent la méthode hybride et la méthode Clean-hybride. La méthode la formation de voie classique est désavantagée en raison de son besoin de nombreux microphones de mesure. De même, la méthode inverse est désavantagée en raison du besoin d'information a priori sur les sources. La régularisation Tikhonov classique fournit des améliorations dans. la stabilité de la solution; cependant elle reste désavantageuse en raison de son exigence d'imposer une pénalité plus forte pour des positions de source non détectées. Des sources cohérentes et incohérentes peuvent être résolues par la formation de voies généralisée inverse (L1-GIB). Cet algorithme peut identifier les sources multi- polaires aussi bien que les sources monopolaires. Cependant, l'identification de source par la formation de voies généralisée inverse prend beaucoup de temps et exige un ordinateur avec une capacité de mémoire élevée. La méthode hybride est une nouvelle méthode de régularisation qui implique l'utilisation d'un traitement par formation de voie a priori pour définir une norme discrète et dépendante des données pour la régularisation du problème inverse. En comparaison avec la formation de voie classique et la méthode inverse, l'approche hybride (régularisation par formation de voie) fournit des cartographies améliorées d'amplitudes de sources sans aucune complexité supplémentaire substantielle. Bien que la méthode hybride lève les limitations des méthodes classiques, l'application de cette méthode pour l'identification de sources de faible puissance en présence de sources de forte puissance n'est pas satisfaisante. On peut expliquer ceci par la plus grande pénalisation appliquée à la source plus faible dans la méthode hybride, qui aboutit à la sous-estimation de l'amplitude de cette source. Pour surmonter ce défaut, la méthode Clean-SC et la méthode Clean-hybrides proposée qui est une combinaison de la méthode hybride et de Clean-SC sont appliquées. Ces méthodes éliminent l'effet des sources fortes dans les cartographies de puissance de sources pour identifier les sources plus faibles. Les méthodes proposées qui représentent la contribution principale de cette thèse conduisent à des résultats fiables et ouvrent des nouvelles voies de recherche. L'étude théorique de toutes les approches est menée pour divers types de sources et de configurations microphoniques. Pour valider l'étude théorique, plusieurs expériences en laboratoire sont réalisées à Université de Sherbrooke. Les méthodes proposées ont été appliquées aux données de bruit mesurées d'une turbo-soufflante Pratt & Whitney Canada pour fournir une meilleure résolution spatiale des sources acoustique et une solution robuste avec un nombre limité des microphones de mesure comparé aux méthodes existantes.

Current European legislation aims to limit vehicle noise emissions since many people are exposed to road traffic noise in urban areas. Vehicle pass-by noise is measured according to the international standard ISO 362 in Europe. More recent investigations of urban traffic have led to the proposal of a revised ISO 362 which includes a constant-speed test in addition to the traditional accelerated test in order to determine the pass-by noise value. In order to meet the legal pass-by noise requirements, vehicle manufacturers and suppliers must analyse and quantify vehicle noise source characteristics during the development phase of the vehicle. In addition, predictive tools need to be available for the estimation of the final pass-by noise value. This thesis aims to contribute to the understanding of vehicle pass-by noise and of the characteristics of the vehicle noise sources contributing to pass-by noise. This is supported through an extensive literature review in which current pass-by noise prediction methods are reviewed as well. Furthermore, three vehicle noise sources are replicated experimentally under laboratory conditions. This involves an orifice noise source, represented by a specially designed loudspeaker on a moving trolley, shell noise, represented by a metal cylinder structure, and tyre cavity and sidewall noise, represented by an annular membrane mounted on a tyre-like structure. The experimentally determined directivity characteristics of the acoustically excited noise sources are utilised in the pass-by noise prediction method. The predictive results are validated against experimental measurements of the three vehicle-like noise sources made within an anechoic chamber.

Afin de réduire les consommations de carburant et les émissions de CO2, des technologies comme la désactivation de cylindres ont été développées. Deux stratégies ont été à l’étude chez le Groupe PSA, il s’agit de désactivations appelées fixe ou tournante en fonction du nombre de cylindres désactivés au cours d’un cycle moteur. Des modifications importantes du bruit et des vibrations transmises dans l’habitacle de la voiture en sont les conséquences ce qui modifie nettement la perception du confort par le conducteur de la voiture. Ce travail de recherche s’intéresse aux modifications de confort perçu par le conducteur dues à ces différentes stratégies appliquées au moteur ainsi qu’aux solutions potentielles qui permettraient d’améliorer ce confort. Parmi ces solutions se trouve le principe de sonification en temps réel du bruit moteur. Pour répondre à ces questions, cinq tests perceptifs sont réalisés. Les deux premiers consistent en l’évaluation du confort global dans différentes configurations ainsi qu’à la validation de l’utilisation d’un simulateur vibro-acoustique. Ces expériences ont montré qu’une des stratégies de désactivation était jugée significativement plus inconfortable que les autres. Par la suite, une seule des stratégies sera retenue. La troisième expérience permet de déterminer un seuil d’acceptabilité entre les sollicitations du moteur avec désactivation et celles du moteur habituel. Ceci afin de fixer une cible pour laquelle l’environnement vibro-acoustique serait acceptable. Dans les deux dernières expériences, deux solutions permettant d’atteindre cette cible sont simulées. La première consiste à modifier la plage de régime moteur ou à lieu la désactivation, la deuxième consiste à assouplir les suspensions horizontales afin de limiter les résonances vibratoires à faible régime. / The technology of cylinder of deactivation has been developed in order to reduce gas consumption and CO2 emissions. Two strategies were studied at groupe PSA called fixed and rotating deactivations depending on the number of cylinders deactivated per engine cycle. This implies non neglecting modifications of sound and vibrations transmitted to the car cabin depredating the global comfort of the car. This research work focused on how driver’s comfort was altered by these engine configurations and how it would be possible to improve this comfort. Among the solutions possible, appears the principle of real-time sonification of the engine noise. To answer these questions, five perceptual experiments have been conducted. First, the aim was to evaluate global comfort with different engine configurations and validate the use of a vibro-acoustic simulator. This showed that one deactivation strategy was significantly reducing the comfort evaluation. Then, we focused on the second strategy which was also considered as not comfortable. On the third experiment, we were interested in finding an acceptable threshold between the vibrations and sounds with the deactivation and with the usual engine configuration. This led to a target of signal to reach in order to provide acceptable situations in terms of sound and vibrations. In the last two experiments, we were interested in the simulation of two solutions about the deactivation settings that would reduce the annoyance: the modification of the engine speed range in which the deactivation occurs and the softening of horizontal suspensions part in order to reduce vibrations resonances at low engine speed.

The diploma thesis is focused on analysis of noise level of mobile power vehicles in relation to motor operation mode and its evaluation. The thesis core lies within measurement of acoustic pressure levels at four vehicles in different motor operation modes by two audio-noise meters. One meter was places within the cabin, the other outside. The results of the work showed a development in reducing noise at modern power vehicles.

This study presents comprehensive active cancellation of booming noise caused by the engine and the driveline inside a passenger car. In modern noise control systems for vehicles, booming noise caused by engine harmonics could be effectively suppressed by employing active noise control. However, practical attempts or studies for the active suppression of driveline booming noise are scarce. One of the reasons may be that since the booming noise caused by the driveline is not harmonic with the engine speed, reference signals cannot be generated conventionally. Thus, passive approaches are generally employed to improve the driveline noise. To address this limitation, we propose a method for generating reference signals from engine revolution speed to suppress the driveline noise, such as propeller shaft and tire noise. Reference signals for driveline noise suppression were generated using the information from the torque converter, gear ratio, and final drive ratio. A practical active noise control system was implemented in a six-cylindered large sedan to validate the proposed method. The experimental results showed that the engine firing order was suppressed by 8.0 dB. Moreover, the first order of the propeller shaft and the second and third orders of the tires were suppressed by 5.5 dB, 3.9 dB, and 2.3 dB for entire seat positions. Furthermore, the results presented in this study were considered effective for improving annoyance perception through subjective evaluation.