This thesis focuses on adaptive feedback control for low frequency acoustic energy absorption in acoustic enclosures. The specific application chosen for this work is the reduction of high interior sound pressure levels (SPL) experienced during launch within launch vehicle payload fairings. Two acoustic enclosures are used in the research: the first being a symmetric cylindrical duct and the other being a full scale model of a payload fairing. The symmetric cylindrical duct is used to validate the ability of the adaptive controller to compensate for large changes in the interior acoustical properties. The payload fairing is used to validate that feedback control, for a large geometry, does absorb acoustic energy. The feedback controller studied in this work is positive position feedback (PPF) used in conjunction with high and low pass Butterworth filters. An algorithm is formed from control experiments for setting the filter parameters of the PPF and Butterworth filters from non-adaptive control simulations and tests of the duct and payload fairing. This non-adaptive control shows internal SPL reductions of 2.2 dB in the cylindrical duct for the frequency range from 100 to 500 Hz and internal SPL reductions of 4.2 dB in the full scale fairing model for the frequency range from 50 to 250 Hz. The experimentally formed control algorithm is then used as the basis for an adaptive controller that uses the collocated feedback signal to actively tune the control parameters. The cylindrical duct enclosure with a movable end cap is used to test the adaptation properties of the controller. The movable end cap allows the frequencies of the acoustic modes to vary by more than 20 percent. Experiments show that a 10 percent change in the frequencies of the acoustic modes cause the closed-loop system to go unstable with a non-adaptive controller. The closed-loop system with the adaptive controller maintains stability and reduces the SPL throughout the 20 percent change of the acoustic modes' frequencies with a 2.3 dB SPL reduction before change and a 1.7 dB SPL reduction after the 20 percent change. / Master of Science

Increasing costs for space shuttle missions translate to smaller, lighter, and more flexible satellites that maintain or improve current dynamic requirements. This is especially true for optical systems and surfaces. Lightweight, inflatable structures, otherwise known as gossamer structures, are smaller, lighter, and more flexible than current satellite technology. Unfortunately, little research has been performed investigating cost effective and feasible methods of dynamic analysis and control of these structures due to their inherent, non-linear dynamic properties. Gossamer spacecraft have the potential of introducing lenses and membrane arrays in orbit on the order of 25 m in diameter. With such huge structures in space, imaging resolution and communication transmissibility will correspondingly increase in orders of magnitude. A daunting problem facing gossamer spacecraft is their highly flexible nature. Previous attempts at ground testing have produced only localized deformation of the structure's skin rather than excitation of the global (entire structure's) modes. Unfortunately, the global modes are necessary for model parameter verification. The motivation of this research is to find an effective and repeatable methodology for obtaining the dynamic response characteristics of a flexible, inflatable structure. By obtaining the dynamic response characteristics, a suitable control technique may be developed to effectively control the structure's vibration. Smart materials can be used for both active dynamic analysis as well as active control. In particular, piezoelectric materials, which demonstrate electro-mechanical coupling, are able to sense vibration and consequently can be integrated into a control scheme to reduce such vibration. Using smart materials to develop a vibration analysis and control algorithm for a gossamer space structure will fulfill the current requirements of space satellite systems. Smart materials will help spawn the next generation of space satellite technology. / Master of Science

The research presented in this thesis focuses on the use of feedback control for lowering acoustic levels within launch vehicle payload fairings. Due to the predominance of conical geometries within payload fairings, our work focused on the analytical modeling of conical shrouds using modal and impedance based models. Incorporating an actuating boundary condition within a sealed enclosure, resonant frequencies and mode shapes were developed as functions of geometric and mechanical parameters of the enclosure and the actuator. Using a set of modal approximations, a set of matrix equations have been developed describing the homogeneous form of the wave equation. Extending to impedance techniques, the resonant frequencies of the structure were again calculated, providing analytical validation of each model. Expanding this impedance model to first order form, the acoustic model has been coupled with actuator dynamics yielding a complete model of the system relating pressure to control voltage. Using this coupled state-space model, control design using Linear Quadratic Regulator and Positive Position Feedback techniques has also been presented. Using the properties of LQR analysis, an analytical study into the degree of coupling between actuator and cavity as a function of actuator resonance has been conducted. Constructing an experimetnal test-bed for model validation and control implementation, a small sealed enclosure was built and outfitted with sensors. Placing a control speaker at the small end of the cone the large opening was sealed with a rigid termination. An internal acoustic source was used to excite the system and pressure measurements were captured using an array of microphones located throughout the conic section. Using the parameters of this experimental test-bed, comparisons were made between LQR and PPF control designs. Using an impulse disturbance to excite the system, LQR simulations predicted reductions of 53.2% below those of the PPF design, while the control voltages corresponding to these reductions were 43.8% higher for LQR control. Actual application of these control designs showed that the ability to manually set PPF gains made this design technique much more convenient for actual implementation. Yielding overall attenuation of 38% with control voltages below 200 mV, single-channel low authority control was seen to be an effective solution for low frequency noise reduction. Control was then expanded to a larger geometry representative of Minotaur fairings. Designing strictly from experimental results, overall reductions of 38.5% were observed. Requiring slightly larger control voltages than those of the conical cavity, peak voltages were still found to be less than 306 mV. Extrapolating to higher excitation levels of 140 dB, overall power requirements for 38.5% pressure reductions were estimated to be less than 16 W. / Master of Science

Notre recherche est particulièrement centrée sur le Sipo-SD, principale organisation de police allemande chargée de la répression de la Résistance. L’idée commune d’une « Gestapo », unique organisation allemande en charge de la répression de la Résistance, s’avère en réalité très sommaire. Une des questions centrale est de savoir comment la Gestapo s’inscrit dans l’antenne du Sipo-SD de Marseille. Nous prêterons tout l’attention sur la place de la Wehrmacht et, le rôle joué par l’Abwehr, la Feldgendarmerie. L’analyse de la 8ᵉ compagnie de la division Brandebourg et de la Geheim Feld Polizei (GFP) apportera un éclairage nouveau sur le dispositif répressif. L’examen du kommando de la section VI du consulat général d’Allemagne ou du Sonderkommando AS contribuera à une connaissance plus fine des acteurs. On ne peut traiter de la répression de la Résistance sans s’interroger sur la place de la Milice, la principale force répressive du régime de Vichy dans ce dispositif. Nous poursuivrons par l’étude du personnel du KDS de Marseille. Les auxiliaires français du Sipo-SD n’ont pas jamais fait l’objet d’une étude rigoureuse, ce que nous tenterons de faire pour Marseille. Quel est l’apport du PPF au Sipo-SD ? Enfin, nous terminerons en mettant l’accent sur les grandes opérations conduites par le KDS contre la Résistance marseillaise et régionale au cours de la période paroxystique de la répression de l’été 1944. L’opération Mercenary, les affaires Catilina et Antoine permettront d’analyser comment fonctionne la répression allemande dans la période qui précède la Libération et où elle atteint son plus haut niveau de violence. / Our research is particularly centered on Sipo-SD, main organization of German police in charge of the repression of the Resistance. The common idea of a "Gestapo", an unique German organization in charge of the repression of the Resistance, turns out in reality very basic. One of the questions power plants is to know how the Gestapo joins in the office of Sipo-SD of Marseille. We shall pay quite particularly the attention on the place of the Wehrmacht within this device, the role played by Abwehr, Feldgendarmerie. The analysis of the 8th company of the division Brandenburg and of the Geheim Feld Polizei (GFP) will give a new perspective on the repressive device. The examination of the Kommando squad of the section VI of the general consulate of Germany or Sonderkommando AS will contribute to a finer knowledge of the actors of the plan. We cannot deal with the repression of the resistance without wondering about the place of the Milice, the main repressive strength of the regime of Vichy in this device. We shall continue by the study of the staff of the KDS of Marseille. But the French auxiliaries of the Sipo-SD were never the object of a rigorous study, what we shall try to make for Marseille. Finally, we shall end by emphasizing the big operations led by the KDS against the Resistance from Marseille and regional during the paroxystic period of the repression of the summer, 1944. The operation Mercenary, the affairs Catilina and Antoine shall allow to analyze how works the German repression for the period which precedes the liberation and where it reaches its highest level of violence.

Die KE-Familie ist das am ausführlichsten untersuchte Beispiel für eine angeborene spezifische Sprachstörung. Die Sprachstörung in dieser Familie wird durch eine heterozygote Punktmutation im FoxP2-Gen hervorgerufen, die R553H-Mutation. Die betroffenen Mitglieder der Großfamilie haben Defizite beim Erlernen komplexer orofazialer Bewegungsabläufe als Grundlage des fließenden Sprechens und zeigen Störungen beim Sprachverständnis und beim Schreiben. Untersuchungen an der KE-Familie und an Knockout-Tieren hatten Hinweise auf eine Beteiligung des Kleinhirns an der Sprachstörung der KE-Familie geliefert. Entsprechend war zu erwarten, dass genauere Kenntnisse über den Einfluss vom FoxP2-Gen auf Entwicklung und Funktion des Kleinhirns helfen könnten, die Funktion von FoxP2 und seine Rolle bezüglich dieser Sprachstörung, aber auch in Hinblick auf die Sprachfähigkeit des Menschen weiter aufzuschlüsseln. Die Experimente, die der vorliegenden Promotionsarbeit zu Grunde liegen, erforschten erstmals den Einfluss der KE-Mutation im FoxP2-Gen auf synaptischer Ebene durch Untersuchungen am in der Literatur ausführlich beschriebenen erregenden Schaltkreis im Kleinhirnkortex von heterozygoten R552H-Mäusen. Elektrophysiologische Messungen dienten dazu, die Verschaltung der Parallelfasern und Kletterfasern auf die Purkinjezelle auf Veränderungen der Übertragungseigenschaften zu prüfen. Durch Induktion von Langzeitdepression und Paarpulsbahnung an der Parallelfaser-Purkinjezell-Synapse sollte die synaptische Plastizität untersucht werden. Es zeigten sich eine intakte Verschaltung der erregenden Eingänge auf die Purkinjezelle, jedoch Veränderungen der Langzeit- und der Kurzzeitplastizität: Nach Induktion von Langzeitdepression entwickelte sich diese signifikant schneller. Die Paarpulsbahnung war bei kurzen Interstimulusintervallen signifikant verstärkt. Die Befunde sprechen für einen Einfluss des FoxP2-Gens auf die synaptischen Eigenschaften im Kleinhirnkortex. Die Aufschlüsselung dieses Einflusses und seine Bedeutung für die Sprachstörung der KE-Familie und die Sprachentwicklung beim Menschen ist Gegenstand weiterer Forschung.

<p>During a make ready in a web offset press it is important to produce as little waste as possible. Reducing the amount of waste yields savings of both time and money. One way to do faster make ready is to preset the ink keys of the press before it is started. </p><p>This diploma work, carried out at Sörmlands Grafiska Quebecor AB in the city of Katrineholm, Sweden, examines how the ink key preset may be done using low- resolution digital images stored in the vendor independent data format CIP3 PPF. The press that has been used has a control interface that is not accessible from the outside. This feature is shared with a lot of older presses. Therefore several methods of how to present and collect ink key settings using offline methods have been tested. </p><p>To investigate the relationship between mean coverage over one ink zone and its corresponding ink key opening data from a 32-page web offset press has been collected. The mean coverage was taken from the CIP3 PPF files that were related to the collected print jobs. </p><p>The relationship that was found between the coverage and the opening can be described with a transfer curve (one curve per printing unit and side). Using as few as three print jobs of high quality (density and dot gain within given tolerances) a first set of transfer curves may be created. These are close to the real ones and using print jobs where the ink key presettings have been calculated the transfer curves may be calibrated to perform better and better presetting calculations. To generate and calibrate the transfer curves and to extract the mean coverage values from the CIP3 PPF files and recalculate these to presetting values a computer program called IKPS (Ink Key Presetting System) was made. IKPS was made using MATLAB from MathWorks INC. </p><p>IKPS have been tested for ink key presetting during a number of print jobs. Even though the transfer curves were uncalibrated the system performed well. As comparison the results from a plate scanner was used. Even if online transfer of the presetting values is preferable the big advantage with the IKPS is that it is an offline system and therefore it is possible to implement it on any kind of offset press, old as well as new. In order to generate reliable transfer curves the print jobs used for calibration must be of high printing quality and representative for that particular press. How the ink key presettings are presented in the press control room depends on what kind of press it is. IKPS works with CIP3 PPF files as well as low-resolution cmyk tiff files.</p>

During a make ready in a web offset press it is important to produce as little waste as possible. Reducing the amount of waste yields savings of both time and money. One way to do faster make ready is to preset the ink keys of the press before it is started. This diploma work, carried out at Sörmlands Grafiska Quebecor AB in the city of Katrineholm, Sweden, examines how the ink key preset may be done using low- resolution digital images stored in the vendor independent data format CIP3 PPF. The press that has been used has a control interface that is not accessible from the outside. This feature is shared with a lot of older presses. Therefore several methods of how to present and collect ink key settings using offline methods have been tested. To investigate the relationship between mean coverage over one ink zone and its corresponding ink key opening data from a 32-page web offset press has been collected. The mean coverage was taken from the CIP3 PPF files that were related to the collected print jobs. The relationship that was found between the coverage and the opening can be described with a transfer curve (one curve per printing unit and side). Using as few as three print jobs of high quality (density and dot gain within given tolerances) a first set of transfer curves may be created. These are close to the real ones and using print jobs where the ink key presettings have been calculated the transfer curves may be calibrated to perform better and better presetting calculations. To generate and calibrate the transfer curves and to extract the mean coverage values from the CIP3 PPF files and recalculate these to presetting values a computer program called IKPS (Ink Key Presetting System) was made. IKPS was made using MATLAB from MathWorks INC. IKPS have been tested for ink key presetting during a number of print jobs. Even though the transfer curves were uncalibrated the system performed well. As comparison the results from a plate scanner was used. Even if online transfer of the presetting values is preferable the big advantage with the IKPS is that it is an offline system and therefore it is possible to implement it on any kind of offset press, old as well as new. In order to generate reliable transfer curves the print jobs used for calibration must be of high printing quality and representative for that particular press. How the ink key presettings are presented in the press control room depends on what kind of press it is. IKPS works with CIP3 PPF files as well as low-resolution cmyk tiff files.

Blocking the contents of the pterygopalatine fossa (PPF) is a highly effective method in alleviating pain in trigeminal neuralgia (TN) and other facial pain syndromes. This, however, is not a widely used technique, due to the difficulty in locating the PPF which is obscured by bony and soft tissue structures. Despite the various unspecific techniques that have been attempted, in many cases radiography still seems to be used as it is the most effective method in locating the PPF. The aim of this study was therefore to achieve a safe and alternative method of locating the PPF including its contents without the aid of radiography. A total of 160 skulls from the Pretoria Bone Collection at the University of Pretoria were used. Distinct anatomical landmarks and the use of existing and new anthropometric measurements were used to define the location of the PPF in any individual. Regression analysis provided the strength of influence each measurement had on the location of the PPF. From the results, two mathematical formulae were devised (one for each side). These formulae were tested on 47 cadavers by substituting the measurements of each individual into the created formulas. A needle was then inserted at the calculated points, and the area around the needle dissected to determine whether or not it was in the PPF. Our results showed an accuracy of 65.22% on the right and 54.35% on the left. It is hoped that this new technique will aid researchers and clinicians alike in the management of various pain disorders as well as pain management during surgery. AFRIKAANS : Daar is bevind dat ‘n lokale verdowingsblok van die inhoud van die pterygopalatine fossa (PPF) die pyn effektief verlig vir trigeminale senuweepyn, sowel as ander pyn sindrome. Die tegniek word egter nie gereeld gebruik nie as gevolg daarvan dat dit moeilik is om die PPF te betree deurdat dit deur verskeie benige en sagte weefsels verberg word. Die literatuur beskryf verskeie onspesifieke metodes om die prosedure uit te voer, maar in die meeste gevalle moes radiografie gebruik word om sukses te behaal. Die doel van hierdie projek was om ’n alternatiewe metode te ontwikkel wat veilige en effektiewe toegang tot die PPF bied, sonder om radiografie te gebruik. ’n Totaal van 160 skedels was gebruik om anatomies landmerke en bestaande sowel as nuwe antropologiese metings te maak. Regresie analise het die sterkte van die invloed van die onderskeie metings met die pterygopalatine fossa gemeet. Vanuit die resultate van die statistiese analise is twee formules ontwerp (een vir elke kant van die gesig). Die formules was getoets op 47 kadavers deur die metings vir elke individu in die formules te plaas. ‘n Naald is dan geplaas in die uitgewerkte punt, die area om die naald was gedisekteer om te sien of die naald in die fossa en dus by die ganglion was of nie. Die resultate toon ‘n akkuraatheid van 65.22% aan die regterkant en 54.35% aan die linkerkant. Daar word gehoop dat hierdie nuwe tegniek ‘n effektiewe manier van pyn behandeling word in verskeie pyn sindrome sowel as gedurende chirurgie vir beide navorsers en chirurge. / Dissertation (MSc)--University of Pretoria, 2011. / Anatomy / unrestricted

No description available.

Aircraft and satellite structures are exposed to a wide range of temperatures during normal operation cycles. These fluctuations in temperature may result in significant changes of the structural dynamics. Aircraft, automotive, and satellite structures are also subject to various vibration sources. Passive and active vibration suppression techniques have been developed to minimize acoustic noise and fatigue stress damage. Featuring low weight solutions and high performance, active control techniques are becoming increasingly common. Structures with varying dynamics require more sophisticated active control techniques, such as adaptive control. This research uses a special vibration test rig for evaluating the performance of different vibration suppression systems on a representative aircraft panel. The test panel is clamped rigidly in a frame and can be excited in various frequencies with an electromagnetic shaker. To simulate temperature fluctuations the temperature on the panel can be increased up to 65°C (150°F). Smart material based sensors and actuators are used to interface the mechanical system with the electronic controller. The active controller utilizes three positive position feedback (PPF) filters implemented through a digital signal processor board. This research develops two different adaptation methods to perform vibration suppression in the presence of thermally induced frequency changes of the representative panel. To adjust the PPF filter parameters an open-loop adaptation method and an auto-tuning method are investigated. The open-loop adaptation method uses a measurement of the plate temperature and a look-up table with pre-determined parameters to update the filters accordingly. The auto-tuning methods identifies the frequencies of the poles and zeros in the structure's collocated transfer function. From the knowledge of the pole and zero locations the optimal PPF parameters are calculated online. The results show that both adaptation methods are capable of reducing the vibration levels of the test specimen over the temperature range of interest. Three PPF filters with parameter adaptation through temperature measurement achieve magnitude reductions of the resonance peaks as high as 13.6 decibel. Using the auto-tuning method resonance peak reductions up to 17.4 decibel are possible. The pole/zero identification routine proves to detect the frequencies correctly. The average identification error remained at around one percent even in the presence of external disturbances. / Master of Science