Haptic systems incorporate many different components, ranging from virtual simulations, physical robotic interfaces (super joysticks), robotic slaves, signal communication, and digital control; two-port networks offer compact and modular organization of such haptic components. By establishing specific stability properties of the individual component networks, their control parameters can be tuned independently of external components or interfacing environment. This allows the development of independent haptic two-port networks for interfacing with a class of haptic components. Furthermore, by using the two-port network with virtual coupling paradigm to analyze linear haptic systems, the complete duality between an admittance controlled device with velocity (position) feedback and virtual coupling can be compared to an impedance controlled device with force feedback and virtual coupling. This research first provides background on linear haptic two-port networks and use of Llewelyn's Stability Criterion to prove their stability when interfaced with passive environments, with specific comments regarding application of these linear techniques to nonlinear systems. Furthermore, man-machine interaction dynamics are addressed, with specific attention given to the human is a passive element assumption and how to include estimated human impedance / admittance dynamic limits into the two--port design. Two--port numerical tuning algorithms and analysis techniques are presented and lay the groundwork for testing of said haptic networks on HuRBiRT (Human Robotic Bilateral Research Tool), a large scale nonlinear hybrid active / passive haptic display. First, two-port networks are numerically tuned using a linearized dynamic model of HuRBiRT. Resulting admittance and impedance limits of the respective networks are compared to add insight on the advantages / disadvantages of the two different implementations of haptic causality for the same device, with specific consideration given to the advantage of adding force feedback to the impedance network, selection of virtual coupling form, effects of varying system parameters (such as physical or EMF damping, filters, etc.), and effects of adding human dynamic limits into the network formulation. Impedance and admittance two-port network implementations are experimentally validated on HuRBiRT, adding further practical insight into network formulation. Resulting experimental networks are directly compared to those numerically formulated through use of HuRBiRT's linearized dynamic models.

The master’s thesis is focused on the analysis and modeling of power line communication with aim to implement power line channel simulator in the programming environment Matlab. At the beginning of the thesis are summarized basic information about the PLC communication, its basic distribution in terms of frequency bands and are also mentioned advantages and disadvantages. The emphasis on the meaning and importance of modeling with the aim to analyze PLC communication channel is specified further. The following is a detailed description of the current power lines communication models. Power line channel simulator was created on the basis of mathematical analysis for low-voltage (LV) distribution networks. The created simulator uses a model of cascaded two-ports and works in random or fixed mode. Input parameters are real topologies, different types of loads and cables. RLC resonant circuit as a frequency selective impedance is also included in impedance models. Based on the obtained results was performed the analysis, determined the critical parameters and extreme values. Comparison of effectiveness of created simulator was processed on the basis of available simulators from other authors. Two versions of simulator were created using the results obtained under comparison of effectiveness. For comparison was also performed real measurement on a simple topology. The experimental measurements results have been implemented in the simulator.

A number of experimental and theoretical studies, performed in the field of technical flow duct acoustics are presented in this thesis. The acoustical methods treated are implemented on turbocharged IC-engines and engine gas exchange system components. A new method based on the well-known two-load technique has been developed. The method was applied to characterise the source data of various piston-engines with non-linear behaviour including a 6 cylinder turbo-charged truck diesel engine. The source characterisation results were compared to the results obtained using the linear two-load technique. It was demonstrated that the new non-linear multi-load technique gives improved results when the source is slightly non-linear. The use of active one-port models has been tested to characterize an air terminal device (ATD) as a source of flow generated noise. In order to predict the noise generation at different operating points of the device a scaling law was derived and verified. In the experimentally derived scaling law a flow speed dependence of 3 was found for the narrow band spectra, corresponding to a dipole-like behavior of the source in the plane wave range. The proposed technique was validated successfully and the results indicated a good prediction of in-duct sound generation by the air terminal device. Sound reflection from hot flow duct openings has been investigated experimentally. The reflection coefficient was measured for flow temperatures up to 500 ºC and jet velocities up to 108m/s. The results have been compared with famous Munt’s theory. It was concluded that at low Mach number and Helmholz number cases the results agree well with the Munt’s model. This was the first experimental validation of the theory for hot flow conditions. Experimental procedures to determine the sound transmission through automotive turbo-charger compressors were developed and described in detail. An overview of a unique turbocharger testing facility established at KTH CICERO in Stockholm is given. The facility can be used to measure acoustic two-port data for turbo-compressors. Results from measurements on a passenger car turbo-compressor are presented and the influence of operating conditions on the sound transmission is discussed. Current wave action models developed in CMT for computation of the gas exchange processes in I.C. engines have been implemented to determine the acoustic wave transmission through the turbo- compressor. The models are validated with the experimental data and the results are presented for different operating conditions of a Volvo passenger car turbo-compressor. / QC 20100809

The first aim of this diploma thesis is to clarify problems with circuit elements described by the fractional-order dynamics, show their basic properties and possible applications in circuits with lumped parameters. The second topic is covering the synthesis of two-terminal devices which have different fractional-orders for requested phase shifts. For this kind of devices, the thesis also describes their optimization and approximation in the frequency domain and subsequent implementation in the form of passive ladder structures. The final part of diploma work will be focused on practical realization of universal fractional PID controller and the verification of proper function of this multi-port in various configurations to prove its correct function via real measurement of frequency and time responses.

The increased use of the diesel engine in the passenger car, truck and bus market is due to high efficiency and lower fuel costs. This growing market share has brought with it several environmental issues for instance soot particle emission. Different technologies to remove the soot have been developed and are normally based on some kind of soot trap. In particular for automobiles the use of diesel particulate traps or filters (DPF:s) based on ceramic monolithic honeycombs are becoming a standard. This new exhaust system component will affect the acoustics and also work as a muffler. To properly design exhaust systems acoustic models for diesel particulate traps are needed. The first part of this thesis considers the modelling of sound transmission and attenuation for traps that consist of narrow channels separated by porous walls. This work has resulted in two new models an approximate 1-D model and a more complete model based on the governing equations for a visco-thermal fluid. Both models are expressed as acoustic 2-ports which makes them suitable for implementation in acoustic software for exhaust systems analysis. The models have been validated by experiments on clean filters at room temperature with flow and the agreement is good. In addition the developed filter models have been used to set up a model for a complete After Treatment Device (ATD) for a passenger car. The unit consisted of a chamber which contained both a diesel trap and a Catalytic Converter (CC). This complete model was also validated by experiments at room temperature. The second part of the thesis focuses on experimental techniques for plane wave decomposition in ducts with flow. Measurements in ducts with flow are difficult since flow noise (turbulence) can strongly influence the data. The difficulties are also evident from the lack of good published in-duct measurement data, e.g., muffler transmission loss data, for Mach-numbers above 0.1-0.2. The first paper in this part of the thesis investigates the effect of different microphone mountings and signal processing techniques for suppressing flow noise. The second paper investigates in particular flow noise suppression techniques in connection with the measurement of acoustic 2-ports. Finally, the third paper suggests a general wave decomposition procedure using microphone arrays and over-determination. This procedure can be used to determine the full plane wave data, e.g., the wave amplitudes and complex wave numbers k+ and k-. The new procedure has been applied to accurately measure the sound radiation from an unflanged pipe with flow. This problem is of interest for correctly determining the radiated power from an engine exhaust outlet. The measured data for the reflection coefficient and end correction have been compared with the theory of Munt [33] and the agreement is excellent. The measurements also produced data for the damping value (imaginary part of the wavenumber) which were compared to a model suggested by Howe [13]. The agreement is good for a normalized boundary layer thickness less than 30-40

Split ring resonator (SRR) is a metamaterial structure which displays negative permeability values over a relatively small bandwidth around its magnetic resonance frequency. Unit SRR cells and arrays have been used in various novel applications including the design of miniaturized microwave devices and antennas. When the SRR arrays are combined with the arrays of conducting wires, left handed materials can be constructed with the unusual property of having negative valued effective refractive indices. In this thesis, unit cells and arrays of single-ring multiple-split type SRR structures are numerically analyzed by using Ansoft&rsquo / s HFSS software that is based on the finite elements method (FEM). Some of these structures are constructed over low-loss dielectric substrates and their complex scattering parameters are measured to verify the numerical simulation results. The major purpose of this study has been to establish equivalent circuit models to estimate the behavior of SRR structures in a simple and computationally efficient manner. For this purpose, individual single ring SRR cells with multiple splits are modeled by appropriate two-port RLC resonant circuits paying special attention to conductor and dielectric loss effects. Results obtained from these models are compared with the results of HFSS simulations which use either PEC/PMC (perfect electric conductor/perfect magnetic conductor) type or perfectly matched layer (PML) type boundary conditions. Interactions between the elements of SRR arrays such as the mutual inductance and capacitance effects as well as additional dielectric losses are also modeled by proper two-port equivalent circuits to describe the overall array behavior and to compute the associated transmission spectrum by simple MATLAB codes. Results of numerical HFSS simulations, equivalent circuit model computations and measurements are shown to be in good agreement.

<p>The increased use of the diesel engine in the passenger car, truck and bus market is due to high efficiency and lower fuel costs. This growing market share has brought with it several environmental issues for instance soot particle emission. Different technologies to remove the soot have been developed and are normally based on some kind of soot trap. In particular for automobiles the use of diesel particulate traps or filters (DPF:s) based on ceramic monolithic honeycombs are becoming a standard. This new exhaust system component will affect the acoustics and also work as a muffler. To properly design exhaust systems acoustic models for diesel particulate traps are needed. The first part of this thesis considers the modelling of sound transmission and attenuation for traps that consist of narrow channels separated by porous walls. This work has resulted in two new models an approximate 1-D model and a more complete model based on the governing equations for a visco-thermal fluid. Both models are expressed as acoustic 2-ports which makes them suitable for implementation in acoustic software for exhaust systems analysis. The models have been validated by experiments on clean filters at room temperature with flow and the agreement is good. In addition the developed filter models have been used to set up a model for a complete After Treatment Device (ATD) for a passenger car. The unit consisted of a chamber which contained both a diesel trap and a Catalytic Converter (CC). This complete model was also validated by experiments at room temperature. The second part of the thesis focuses on experimental techniques for plane wave decomposition in ducts with flow. Measurements in ducts with flow are difficult since flow noise (turbulence) can strongly influence the data. The difficulties are also evident from the lack of good published in-duct measurement data, e.g., muffler transmission loss data, for Mach-numbers above 0.1-0.2. The first paper in this part of the thesis investigates the effect of different microphone mountings and signal processing techniques for suppressing flow noise. The second paper investigates in particular flow noise suppression techniques in connection with the measurement of acoustic 2-ports. Finally, the third paper suggests a general wave decomposition procedure using microphone arrays and over-determination. This procedure can be used to determine the full plane wave data, e.g., the wave amplitudes and complex wave numbers k+ and k-. The new procedure has been applied to accurately measure the sound radiation from an unflanged pipe with flow. This problem is of interest for correctly determining the radiated power from an engine exhaust outlet. The measured data for the reflection coefficient and end correction have been compared with the theory of Munt [33] and the agreement is excellent. The measurements also produced data for the damping value (imaginary part of the wavenumber) which were compared to a model suggested by Howe [13]. The agreement is good for a normalized boundary layer thickness less than 30-40</p>

In search for quieter engines there is a need for a better understanding of the acoustic properties of engine intake and exhaust system components. Besides mufflers which have the purpose of reducing pressure pulses originating from the internal combustion (IC) engine, there are many components in a modern car exhaust and intake system, e.g., air-filters, coolers, catalytic converters, particulate filters - all having an effect on the pressure pulses or sound field in the system. In this work the focus is on the turbocharged IC-engine where both, sound scattering (reflection and transmission) and sound generation from automotive turbochargers are studied. In addition, sound reflection from an open ended pipe, such as the tailpipe of an IC-engine exhaust is investigated.             Accurate and efficient methods to fully characterize turbochargers by measuring the acoustic two-port have been developed.  Compared to earlier work, a number of modifications are suggested for improving the quality of the results. A study on three different automotive turbochargers is also presented, including data for sound scattering for both the compressor and turbine. The results for the transmission of sound, which is of interest for the ability of a turbocharger to reduce noise coming from the engine, is plotted for all tested cases against a dimensionless frequency scale (Helmholtz-number). This makes it possible to generalize the result in order to draw conclusions about the behavior for any turbocharger.              The sound generation was also studied and three different methods to estimate the sound power are suggested. The methods were used to investigate sound generation at different operating points and identify source mechanisms for a turbocharger compressor.             An accurate method for measuring the reflection of plane acoustic waves from a pipe termination in a duct with hot gas flow has been developed and tested. Representing the acoustical conditions at an exhaust tail-pipe, the data obtained is important for effective modeling of exhaust systems. The experimental results of the reflection coefficient were compared with Munt`s theory on flow duct openings. The measurements were carried out for air jet velocities up to Mach 0.4 and for flow temperatures up to 100°C in order to study temperature effects on the reflection properties. It was concluded, that the experimental results agree well with the Munt theory.

[pt] A modelagem da propagação de ondas cilíndricas em materiais elásticos,tradicionalmente tem sido feita a partir de abordagens analíticas, baseadasna teoria de propagação de ondas, ou a partir de métodos numéricos, comoo método dos elementos finitos. Contudo, dependendo da frequência, resultados numéricos transientes podem ser difíceis de serem obtidos, seja pelo custocomputacional, seja pelo tempo despendido para os cálculos. Dentro desse contexto, alguns trabalhos envolvendo transferência de energia por ondas acústicas, utilizando-se de transdutores piezoelétricos, utilizam métodos alternativospara modelagem. Dentre os métodos disponíveis na literatura para a modelagem deste tipo de problema, a abordagem de rede de duas portas, provenienteda análise de circuitos elétricos, mostrou ser consideravelmente proeminente.Nesta tese, utilizando analogias de impedância, o método é trazido para o contexto de propagação de ondas acústicas, resultando em matrizes de transferência compostas por parâmetros de transmissão, ou parâmetros ABCD, comocomumente conhecidos. De fato, resultados iguais com menos esforços computacionais são obtidos a partir desta abordagem. Até o presente momento, essemétodo foi apenas desenvolvido para propagação de ondas planas em sólidoselásticos e materiais piezoelétricos. No entanto, como grande parte das aplicações envolve superfícies curvas, o método neste trabalho é estendido para ocaso de ondas cilíndricas. Os novos parâmetros ABCD encontrados são entãoimplementados em um código computacional, modelando testes pulso-eco epitch-catch dentro de meios cilíndricos. A validação é feita a partir de umaanálise de convergência a partir das respostas adquiridas para diferentes valores de raio interno do canal, uma vez que algumas expressões encontradas paraos parâmetros ABCD se mostraram inversamente proporcionais ao raio. Alémdisso, o método desenvolvido foi capaz de modelar um teste experimental detransmissão de sinal, a partir de um transdutor cilíndrico submerso em umtanque com água, assim como modelar a transmissão do mesmo sinal atravésde uma barreira cilíndrica. / [en] Cylindrical wave propagation in elastic materials has usually been modeled with analytical approaches or with numerical methods, such as the finite element method. However, depending on the frequency, obtaining results can be a hard task, requiring high computational efforts. Within this context, some studies on acoustic energy transfer, using piezoelectric transducers, had adopted alternative methods for modeling wave propagation, by means of acoustic-electric channels. Among the available methods in the literature, the two-port network approach, derived from the electric circuit analysis, proved to be prominent. In this thesis, by using impedance analogies, this method is brought into the context of acoustic wave propagation, leading to transfer matrices based on transmission parameters, or the so-called ABCD parameters. It was verified that the same results with less computational effort were obtained. So far, this method was only developed for the plane wave propagation in elastic solids and piezoelectric materials. However, since many real applications are curved, the two-port network approach is extended for the cylindrical wave case in this work. The novel ABCD parameters are then implemented in a computational routine, modeling pulse-echo and pitch-catch tests inside cylindrical media. The validation was performed by means of a convergence analysis, varying the internal radius of the entire channel, since the new ABCD parameters showed an inverse proportionality with the radius of the layer. Furthermore, the developed method was capable of modeling a signal transmission experimental setup, coming from a cylindrical transducer submerged in a water tank, as well as modeling the transmission of the same signal through a cylindrical barrier.

<p>This thesis contains three papers investigating problems of interest for noise control in ducts.</p><p>The first part of this thesis treats the sound propagation in rectangular ducts with flexible walls. Various experimental techniques are performed to measure the internal sound propagation and radiation to the surrounding. An analytical model is derived to calculate the coupled propagation wavenumber and radiated sound power. The two-port formalism is used.</p><p>The second part starts with the sound propagation in open ended circular straight pipe with airflow (a tailpipe). Various aspects such as: acoustic damping, reflection and transmission at the open termination are investigated. Sound absorption due to vorticity shed at the opening is also treated. The geometry of the opening is then modified (oblique cuts, diffusers) and comparisons with the reference straight pipe is made for the sound transmission and flow induced noise generation. The effect of an upstream bend close to the opening is also investigated.</p><p>In the third part the acoustic impedance of perforated plates are investigated. In particular the application to small perforation ratios ( ≈ 1% ) and holes or slits with apertures of sub-millimetre size, so called micro-perforated plates, are of interest. Linear and non-linear regimes are investigated. A model is derived to calculate the linear acoustic impedance of perforated elements.</p>