Der Risikofaktor Lärm stellt vor allem in urbanen Gebieten ein großes Umweltproblem mit teilweise erheblichen gesundheitlichen Langzeitauswirkungen für die Stadtbevölkerung dar. Dabei hängt die Ausbreitung des Schalls von einer Störquelle, wie z.B. dem Straßenverkehr, besonders auf größeren Strecken von der Atmosphärenstruktur ab. Das Ziel dieser Arbeit bestand darin, den Einfluss der tageszeitlich variierenden urbanen Grenzschicht auf die Schallausbreitung unter Verwendung eines Schallstrahlenmodells abzuschätzen. Basis dieser Berechnungen bildeten analytisch erzeugte urbane Vertikalprofile der Temperatur, Windgeschwindigkeit und Windrichtung. Die Auswertungen der Karten der meteorologisch bedingten Zusatzdämpfung zeigten eine sichtbare zusätzliche Beeinflussung der Schallausbreitung durch die spezielle Struktur der urbanen Grenzschicht. Besonders im Nahbereich der Quelle traten nachts in Windrichtung bei labiler Atmosphärenschichtung Zonen erhöhter Lärmbelastung auf. / Especially in urban regions the risk factor noise is a huge problem, which may have a notable impact on (human) health on long-time scales. The sound propagation of a disturbing source, e.g. traffic noise, depends for larger distances in particular on the structure of the atmosphere. The aim of this study was to estimate the influence of the urban boundary layer on the propagation of sound using a sound ray model. Therefore, urban vertical profiles of temperature, wind speed, and wind direction for day and night time conditions were calculated analytically. The resulting maps considering excess attenuation of sound due to meteorology yielded an additional influence on the sound propagation in consequence of the defined structure of the urban boundary layer. Particularly in downwind areas close to the source the impact of noise increases regionally at night for the cases of unstable atmospheric layering.

Lärm ist ein nach wie vor ungelöstes Umweltproblem. Die wichtigste Lärmquelle in urbanen Räumen ist der Straßenverkehrslärm, der gesundheitsschädliche Langzeitwirkungen haben kann. Die Ausbreitung von Schallwellen bis zum Immissionsort wird, besonders bei längeren Entfernungen, durch die Atmosphärenstruktur beeinflusst. Ziel der vorliegenden Arbeit ist es, diesen Atmosphäreneinfluss auf die Schallausbreitung mit Hilfe von Messungen an Autobahnen in der Nähe von Chemnitz abzuschätzen. Mit je zwei Messstellen in 25 m und 150 m Entfernung von der Autobahn wurde der Effekt der Atmosphärenschichtung und des Windprofils auf die Schallimmission frequenzaufgelöst untersucht. Die Resultate dieser Studie zeigen eine deutliche Variation des über 60 Minuten gemittelten Schalldruckpegels, die auf die unterschiedliche Atmosphärenstruktur zurückgeführt werden kann. Die Messungen ergaben dabei bis zu 5 dB höhere bzw. 11 dB geringere Schallpegel als Ergebnisse von Berechnungen mit Ingenieurmodellen, die den Atmosphäreneinfluss nur sehr vereinfacht enthalten. Es wird außerdem aufgezeigt, wie die Wirkung von Schallschutzbauten an Autobahnen insbesondere durch den Windeinfluss verändert wird. / Noise is still an unsolved environmental problem. Street noise, that will able to cause long-term effects on the state of health, is the main source of noise in urban areas. The sound propagation is influenced by the atmospheric structure, especially for longer distances. This study is aimed at the estimation of the atmospheric influence onto the sound propagation by using measurements at highways near Chemnitz. Two measurement places in distances of 25 m and 150 m from the highway were used to study the effect of atmospheric stability and wind profile on the frequency-resolved sound level. A variation of the averaged (60 minutes) sound level dependent on the atmospheric structure is clearly visible in the results. The measurements yielded up to 5 dB higher and 11 dB lower sound levels in comparison to results of engineering models which contain the atmospheric influence only in a simplified way. Furthermore, the study shows how the impact of noise screens is changed dependent on the wind influence.

This thesis deals with issue of traffic noise, its measurement and data evaluation. Theoretic part of my work concretes basic information about acoustics and also describes and analyzes traffic noise sources of tire/pavement. Next part deals with quite pavement and with measurement methods of traffic noise. Practical part of my thesis contains description, results and evaluation of realized measurement with methods CPX and SPB.

Title: Numerical Methods in Discrete Inverse Problems Author: Marie Kubínová Department: Department of Numerical Mathematics Supervisor: RNDr. Iveta Hnětynková, Ph.D., Department of Numerical Mathe- matics Abstract: Inverse problems represent a broad class of problems of reconstruct- ing unknown quantities from measured data. A common characteristic of these problems is high sensitivity of the solution to perturbations in the data. The aim of numerical methods is to approximate the solution in a computationally efficient way while suppressing the influence of inaccuracies in the data, referred to as noise, that are always present. Properties of noise and its behavior in reg- ularization methods play crucial role in the design and analysis of the methods. The thesis focuses on several aspects of solution of discrete inverse problems, in particular: on propagation of noise in iterative methods and its representation in the corresponding residuals, including the study of influence of finite-precision computation, on estimating the noise level, and on solving problems with data polluted with noise coming from various sources. Keywords: discrete inverse problems, iterative solvers, noise estimation, mixed noise, finite-precision arithmetic - iii -

This thesis deals with the evaluation of noise exposure in the agricultural cooperative Hosín ? Dobrejovice. The aim of this work was to measure noise levels in the dairy barn area and its surroundings, during these processes work: milking, feeding, removal of excrement, bedding etc. Measurements were carried out in summer and autumn. During the measurement noise was the largest source of agricultural equipment. The results revealed that noise pollution resulting from the operation of agricultural cooperatives Dobrejovice is fair and negative influence on noise pollution does not occur.

Ultraprecision single point diamond turning is required to produce parts with sub-nanometer surface roughness and sub-micrometer surface profiles tolerances. These parts have applications in the optics industry, where tight form accuracy is required while achieving high surface finish quality. Generally, parts can be polished to achieve the desired finish, but then the form accuracy can easily be lost in the process rendering the part unusable. Currently, most mid to low spatial frequency surface finish errors are inspected offline. This is done by physically removing the workpiece from the machining fixture and mounting the part in a laser interferometer. This action introduces errors in itself through minute differences in the support conditions of the over constrained part on a machine as compared to the mounting conditions used for part measurement. Once removed, the fixture induced stresses and the part’s internal residual stresses relax and change the shape of the generally thin parts machined in these applications. Thereby, the offline inspection provides an erroneous description of the performance of the machine. This research explores the use of a single, high resolution, capacitance sensor to quickly and qualitatively measure the low to mid spatial frequencies on the workpiece surface, while it is mounted in a fixture on a standard ultraprecision single point diamond turning machine after a standard facing operation. Following initial testing, a strong qualitative correlation exists between the surface profiling on a standard offline system and this online measuring system. Despite environmental effects and the effects of the machine on the measurement system, the capacitive system with some modifications and awareness of its measurement method is a viable option for measuring mid to low spatial frequencies on a workpiece surface mounted on an ultraprecision machine with a resolution of 1nm with an error band of ±5nm with a 20kHz bandwidth. / Thesis / Master of Applied Science (MASc)