This thesis describes the design and implementation process of two applications (PerMORFer and MoodifierLive) for the interactive manipulation of music performance. Such applications aim at closing the gap between the musicians, who play the music, and the listeners, who passively listen to it. The goal was to create computer programs that allow the user to actively control how the music is performed. This is achieved by modifying such parameters as tempo, dynamics, and articulation, much like a musician does when playing an instrument. An overview of similar systems and the problems related to their development is given in the first of the included papers. Four requirements were defined for the applications: (1) to produce a natural, high quality sound; (2) to allow for realistic modifications of the performance parameters; (3) to be easy to control, even for non-musicians; (4) to be portable. Although there are many similarities between PerMORFer and MoodifierLive, the two applications fulfill different requirements. The first two were addressed in PerMORFer, with which the user can manipulate pre-recorded audio performance. The last two were addressed in MoodifierLive, a mobile phone application for gesture-based control of a MIDI score file. The tone-by tone modifications in both applications are based on the KTH rule system for music performance. The included papers describe studies, methods, and algorithms used in the development of the two applications. Audio recordings of real performance have been used in PerMORFer toachieve a natural sound. The tone-by-tone manipulations defined by the KTH rules first require an analysis of the original performance to separate the tones and estimate their parameters (IOI, duration, dynamics). Available methods were combined with novel solutions, such as an approach to the separation of two overlapping sinusoidal components. On the topic of performance analysis, ad-hoc algorithms were also developed to analyze DJ scratching recordings. A particularly complex problem is the estimation of a tone’s dynamic level. A study was conducted to identify the perceptual cues that listeners use to determinethe dynamics of a tone. The results showed that timbre is as important as loudness. These findings were applied in a partly unsuccessful attempt to estimate dynamics from spectral features. The manipulation of tempo is a relatively simple problem, as is that of articulation (i.e. legato-staccato) as long as the tone can be separated. The modification of dynamics on the other hand is more difficult, as was its estimation. Following the findings of the previously mentioned perceptual study, a method to modify both loudness and timbre using a database of spectral models was implemented. MoodifierLive was used to experiment with performance control interfaces. In particular, the mobile phone’s built-in accelerometer was used to track, analyze, and interpret the movements of the user. Expressive gestures were then mapped to corresponding expressive music performances. Evaluation showed that modes based on natural gestures were easier to use than those created witha top-down approach. / QC 20110607

Traffic is a major source of environmental noise in modern day's society. As a result, the development of new vehicles are subject to heavy governmental legislations. The major noise sources on common road vehicles are engine noise, transmission noise, tire noise and, at high speeds, wind noise. One way to reduce intake and exhaust noise is to attach mufflers to the exhaust pipes. However, to develop prototypes for the evaluation of muffler performance is a costly and time-consuming process. As a consequence, in recent years so called virtual prototyping has emerged as an alternative. Current industrial simulation methodologies are often rather crude, normally only including one-dimensional mean flows and one-dimensional acoustic fields. Also, flow generated noise is rudimentary modeled or not included at all. Hence, improved methods are needed to fully benefit from the possibilities of virtual prototyping. This thesis is aimed at the development of simulation methodologies suitable both as industrial tools for the prediction of the acoustic performance of flow duct systems, as well as for analyzing the governing mechanisms of duct aeroacoustics. Special focus has been at investigating the possibilities to use frequency-domain linearized Navier-Stokes equations solvers, where the equations are solved either directly or as eigenvalue formulations. A frequency-domain linearized Navier-Stokes equations methodology has been developed to simulate sound propagation and acoustic scattering in flow duct systems. The performance of the method has been validated to experimental data and analytical solutions for several cases of in-duct area expansions and orifice plates at different flow speeds. Good agreement has generally been found, suggesting that the proposed methodology is suitable for analyzing internal aeroacoustics. / QC 20110517

Some aspects and properties of the lateral vibration of sandwich beams are investigated, including the concept of apparent bending stiffness and shear modulus, allowing the sandwich beam dynamics to be approximately described by classical beam theory. A sixth order beam model is derived including boundary conditions, and the free and forced response of some beam configurations analyzed. The possibility of computing material parameters from measured eigenfrequencies, i. e. inverse analysis, is considered. The higher order model is also utilized for investigation of the energy propagation through sandwich composite beams and the transmission over different junctions. / QC 20100630

The downscaling and integration of biomedical analyses onto a single chip offers several advantages in speed, cost, parallelism and de-centralization. Acoustic radiation forces are attractive to use in these applications since they are strong, long-range and gentle. Lab-on-a-chip operations such as cell trapping, particle fluorescence activated cell sorting, fluid mixing and particle sorting performed by acoustic radiation forces are exploited in this thesis. Two different platforms are designed, manufactured and evaluated.

For an accurate prediction of the low and medium frequency surface vibration and sound radiation behaviour of porous materials, there is a need to improve the means of estimating their elastic and acoustic properties. The underlying reasons for this are many and of varying origin, one prominent being a poor knowledge of the geometric anisotropy of the cell microstructure in the manufactured porous materials. Another one being, the characteristic feature of such materials i.e. that their density, elasticity and dissipative properties are highly dependent upon the manufacturing process techniques and settings used. In the case of free form moulding, the geometry of the cells and the dimensions of the struts are influenced by the rise and injection flow directions and also by the effect of gravity, elongating the cells. In addition the influence of the boundaries of the mould also introduces variations in the properties of the foam block produced. Despite these complications, the need to predict and, in the end, optimise the acoustic performance of these materials, either as isolated components or as part of a multi-layer arrangement, is growing. It is driven by the increasing demands for an acoustic performance in balance with the costs, a focus which serves to increase the need for modelling their behaviour in general and the above mentioned, inherent, anisotropy in particular. The current work is focussing on the experimental part of the characterisation of the material properties which is needed in order to correctly represent the anisotropy in numerical simulation models. Then an hybrid approach based on a combination of experimental deformation, strain field mapping, flow resistivity measurement and physically based porous material acoustic Finite Element (FE) simulation modelling is described. This inverse estimation linked with high quality measurements is crucial for the determination of the anisotropic coefficients of the porous materials is illustrated here for soft foam and fibrous wool materials. / QC 20100729

No description available.

<p>In this thesis, vibration based techniques for detection of localised surface damages in multistage gearboxes are presented and evaluated.</p><p>A modern vehicle gearbox is a complex system and the number of potential errors is large. For instance, surface damages can be caused by rough handling during assembly. Large savings can be made in the production industry by assuring the quality of products such as gearboxes. An automated quality test as a final step in the production line is one way to achieve this.</p><p>A brief review of available methods for vibration based condition monitoring of gearboxes is given in the opening summary. In the appended papers, a selection of these methods is used to design signal processing procedures for detection of localised surface damages in gearboxes. The procedures include the Synchronous signal averaging technique (SSAT), residual calculation, filtering with a prediction error filter (PEF) based on an AR-model and the use of crest factor and kurtosis as state features. The procedures are fully automatic and require no manual input during calibration or testing. This makes them easy to adapt to new test objects.</p><p>A numerical model, generating simulated gearbox vibration signals, is used to systematically evaluate the proposed procedures. The model originates from an existing model which is extended to include contributions from several gear stages as well as measurement noise. This enables simulation of difficulties likely to arise in quality testing such as varying background noise and modulation due to test rig misalignment. Without the numerical model, the evaluation would require extensive measure-ments. The numerical model is experimentally validated by comparing the simulated vibration signals to signals measured of a real gearbox.</p><p>In the experimental part of the study, vibration data is collected with accelerometers while the gearbox is running in an industrial test rig. In addition to the healthy condition, conditions including three different surface damage sizes are also considered.</p><p>The numerical and the experimental analysis show that the presented procedures are able to detect localised surface damages at an early stage. Previous studies of similar procedures have focused on gear crack detection and overall condition monitoring. The procedures can handle varying back-ground noise and reasonable modulation changes due to misalignment.</p><p>The results show that the choice of sensor position and operating conditions during measure-ments has a significant impact on the efficiency of the fault detection procedures. A localised surface damage excites resonances in the transfer path between the gear mesh and the accelerometer. These resonances amplify the defect signal. The results indicate that it is favourable to choose a speed at which the resonant defect signals are well separated from the gear meshing harmonics in the order domain. This knowledge is of great importance when it comes to quality testing. When a quality test procedure is being developed, it is often possible to choose the operating conditions and sensor positions. It can in fact be more important to choose proper operating conditions than to apply an optimal signal processing procedure.</p>

<p>Traffic is a major source of green house gases. The transport field</p><p>stands for 32 % of the energy consumption and 28 % of the total</p><p>CO2 emissions, where road transports alone causes 84 % of these figures. The energy consumed by a car traveling at constant speed, is</p><p>due to engine ineffiency, internal friction, and the energy needed to</p><p>overcome resisting forces such as aerodynamic drag and rolling resistance.Rolling resistance plays a rather large role when it comes to fuel economy. An improvement in rolling resistance of 10 % can yield fuel</p><p>consumption improvements ranging from 0.5 to 1.5 % for passenger</p><p>cars and light trucks and 1.5 to 3 % for heavy trucks.</p><p>The objective of this thesis is to estimate the power consumption</p><p>in the tyres. To do this a car tyre is modeled with waveguide finite</p><p>elements. A non-linear contact model is used to calculate the contact</p><p>forces as the tyre is rolling on a rough road. The contact forces combined</p><p>with the response of the tyre is used to estimate the input power</p><p>to the tyre structure, which determines a significant part of the rolling</p><p>resistance. The tyre model accounts for: the curvature, the geometry of the</p><p>cross-section, the pre-stress due to inflation pressure, the anisotropic</p><p>material properties and the rigid body properties of the rim. The model</p><p>is based on design data. The motion of the tyre belt and side wall is</p><p>described with quadratic anisotropic, deep shell elements that includes</p><p>pre-stress and the motion of the tread on top of the tyre by quadratic,</p><p>Lagrange type, homogenous, isotropic two dimensional elements.</p><p>To validate the tyre model, mobility measurements and an experimental</p><p>modal analysis has been made. The model agrees very well</p><p>with point mobility measurements up to roughly 250 Hz. The eigenfrequency prediction is within five percent for most of the identified</p><p>modes. The estimated damping is a bit too low especially for the antisymmetric modes. Above 500 Hz there is an error ranging from 1.5 dB</p><p>up to 3.5 dB for the squared amplitude of the point mobility.</p><p>The non proportional damping used in the model is based on an <em>ad</em></p><p><em>hoc </em>curve fitting procedure against measured mobilities.</p><p>The contact force predictions, made by the division of applied</p><p>acoustics, Chalmers University of Technology, are based on a non-linear</p><p>contact model in which the tyre structure is described by its flexibility</p><p>matrix. Topographies of the surface are scanned, the tread pattern is</p><p>accounted for, and then the tyre is ’rolled’ over it. The contact forces</p><p>are inserted into the tyre model and the response is calculated. The</p><p>dissipated power is then calculated through the injected power and the</p><p>power dissipated within each element. Results are promising compared</p><p>to literature and measurements.</p>

<p>For an accurate prediction of the low and medium frequency surface vibration and sound radiation behaviour of porous layered systems, there is a need to improve the means of estimating their elastic and acoustic properties. The underlying reasons for this are many and of varying origin, one prominent being a poor knowledge of the geometric anisotropy of the cell microstructure in the manufactured porous materials. Another one being, the characteristic feature of such materials i.e. that their density, elasticity and dissipative properties are highly dependent upon the manufacturing process techniques and settings used. In the case of free form moulding, the geometry of the cells and the dimensions of the struts are influenced by the rise and injection flow directions and also by the effect of gravity, elongating the cells. In addition the influence of the boundaries of the mould also introduces variations in the properties of the foam block produced. Despite these complications, the need to predict and, in the end, optimise the acoustic performance of these materials, either as isolated components or as part of a multi-layer arrangement, is growing. It is driven by the increasing demands for an acoustic performance in balance with the costs, a focus which serves to increase the need for modelling their behaviour in general and the above mentioned, inherent, anisotropy in particular. The current work is focussing on the experimental part of the characterisation of the material properties which is needed in order to correctly represent the anisotropy in numerical simulation models. A hybrid approach based on a combination of experimental deformation and strain field mapping, and physically based porous material acoustic Finite Element (FE) simulation modelling, is under development which ultimately will provide the anisotropic elastic coefficients and acoustic properties of the porous layered system. The first step, involving new testing methods, is discussed here and demonstrated for a soft foam.</p><p>In addition investigations using laser vibrometers combined with finite element modelling of the Panphonics G1 multi-layered panel elements are also discussed. Variations in the mounting conditions, including globally acting restraints, are evaluated through dynamic measurements and acoustic interaction with the surrounding acoustic field. Results from investigations into different changes of the panel design parameters in order to improve the effectiveness in the low frequency range are presented.</p>

<p>The main objective of this work was to gain an increasing understanding of the properties of vegetation noise and also to the relative ratios of different natural ambient noises to mask wind turbine sound.</p><p>A discrete vegetation noise model was developed and compared to an earlier model showing improved estimations, especially at frequencies below 0.5 kHz. Field measurements of sound from deleafed trees are compared to a deleafed tree model with satisfactory agreement. A wind turbulence model (Sandia method) was coupled to the discrete model and thereby time series of fluctuating vegetation noise can be computed. Several measurements including higher wind speeds than reported in earlier literature were compared to predictions of fluctuating vegetation noise with good agreement.</p><p>Psycho acoustic tests was performed by 36 subjects to determine the signal-to-noise (S/N) ratios when wind turbine noise is inaudible in three different natural ambient noises. The masking threshold varied between -6.5 dBA and -2.7 dBA for coniferous tree noise and sea wave noise respectively. Further tests revealed that at S/N ratios of +3dBA and above the wind turbine noise was considered as the dominant sound source.</p>