100 research outputs found

    Cosmic Ray and Neutrino Astrophysics with the ANITA III Telescope.

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    Ph.D. Thesis. University of Hawaiʝi at Mānoa 2017

    Dynamic Frequency and Voltage Control for a Multiple Clock Domain Microarchitecture

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    We describe the design, analysis, and performance of an on-line algorithm to dynamically control the frequency/voltage of a Multiple Clock Domain (MCD) microarchitecture. The MCD microarchitecture allows the frequency/voltage of micrprocessor regions to be adjusted independently and dynamically, allowing enery savings when the frequency of some regions can be reduced without significantly impacting performance. Our algorithm achieves on average a 19.0% reduction in Energy Per Instriction (EPI), a 3.2% increase in Cycles Per Instruction (CPI), a 16.7% improvement in Energy–Delay Product, and a Power Savings to Performance Degradation ratio of 4.6. Traditional frequency/voltage scaling techniques which apply reductions globally to a fully synchronous processor achieve a Power Savings to Performance Degradation ratio of only 2–3. Our Energy–Delay Product improvement is 85.5% of what has been achieved using an off–line algorithm. These results were achieved using a broad range of applications from the MediaBench, Olden, and Spec2000 benchmark suites using an algorithm we show to require minimal hardware resources

    A proton source in the ALPHA apparatus for precision measurements of antihydrogen and hydrogen

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    The apparent lack of antimatter within our local solar system, the Milky Way, and at Galactic boundaries is inconsistent with the Big Bang hypothesis. This disagreement has motivated many experiments to compare the properties and behaviour of antimatter and matter. The ALPHA (Antihydrogen Laser PHysics Apparatus) experiment produce, trap and study antihydrogen. This synthesis involves antiprotons sourced from the limited schedule of the Antiproton Decelerator facility. The restricted availability hinders the number of novel antiproton experiments, whichcould potentially increase the number of trapped antihydrogen atoms per Antiproton Decelerator cycle. Some of these studies can be performed using a substitute for antiprotons, such as protons, allowing the limited antiprotons to be used during the implementation of their results. This research demonstrates a method that adapts an existing Penning trap to produce protons on demand within reasonable operating time scales of minutes. The availability of protons enables the consideration of new physics studies within ALPHA, including hydrogen formation, trapping, and possibly in situ hydrogen-antihydrogen comparisons. The study produced protons from radiofrequency-drivenelectrons through electron impact ionisation of the cryogenic Penning trap residual gas. The resulting positive ions were sympathetically cooled and compressed by positrons. All positive ions, except protons, were ejected from the trapping potentials using the autoresonance method. The remaining trapped population is approximately (0.9 − 1.2) × 106 protons. This research proves the feasibility of generating protons within the ALPHA apparatus, paving the way for future prospects of hydrogen generation

    Workload prediction based on supply current tracking : a fuzzy logic approach

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    Determination of the chemical composition of cosmic rays in the energy region of 5 EeV with the AMIGA upgrade of the Pierre Auger Observatory

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    Die ultra hochenergetische kosmisch Strahlung besteht aus Teilchen, die mit Energien von über 101810^{18} eV auf die Erde gelangen. Wenn diese auf Atomkerne in der Erdatmosphäre treffen, entstehen Sekundärteilchen. Diese propagieren als ausgedehnte Luftschauer bis zum Boden hin. Zu diesen extrem energiereichen kosmischen Strahlen gibt es noch eine Reihe von offenen Fragen: Was sind deren Quellen? Was sind die Beschleunigungsmechanismen, die ihnen den Ursprung geben, sowie ihre Zusammensetzung (der Anteil von Protonen und verschiedenen Kerntypen)? Welche Mechanismen sorgen für die Unterdrückung bei sehr hohen Energien. Um diese Fragen zu l”osen, werden am Pierre Auger Observatorium kosmische Strahlen mit den höchsten Energien untersucht. Dafür wird eine Hybriddetektionstechnik verwendet, die darauf abzielt, sowohl die Teilchenstatistik zu verbessern als auch systematische Unsicherheiten zu minimieren. Derzeit werden die Messkapzit”aten vom Pierre Auger Observatorium, im Rahmen des AugerPrime Upgrades, verbessert. Dafür werden neue Detektoren wie Radioantennen, Oberflächen-Szintillatordetektoren und Untergrund-Szintillatordetektoren eingesetzt. Das "Auger Muon and Infill for the Ground Array\u27\u27 (AMIGA) zielt darauf ab, sowohl die Nachweisgrenze des Pierre Auger Observatoriums auf Energien von ∼\sim 1016.510^{16.5} eV zu senken als auch den Myongehalt von ausgedehnten Luftschauern direkt zu messen. AMIGA besteht aus einer Reihe von gekoppelten Wasser-Cherenkov- und vergrabenen Szintillatordetektoren, die in zwei überlappenden Dreiecksgittern im Abstand von 433 m und 750 m eingesetzt werden. Jeder Untergrunddetektor hat eine Gesamtfläche von 30 m2\mathrm{m}^2 und ist 2,3 m unter der Erdoberfl”ache vergraben, um es vor der elektromagnetischen Komponenten der Schauer zu schützen. Die Szintillationsebene ist in Kunststoff-Szintillatorstreifen mit eingebetteten optischen Wellenlängenschieberfasern segmentiert, die mit einer Reihe von Silizium-Photomultiplier (SiPMs) gekoppelt sind. In dieser Arbeit stellen wir mehrere Studien über den AMIGA Untergrund-Myonendetektor (UMD) vor, der zwei Betriebsarten hat: den Zähler, der entwickelt wurde, um Myonen direkt zu messen, wenn sie auf den Detektor treffen, und optimiertist, um niedrige Myondichten zu messen, und den Integrator, der es ermöglicht, den Myongehalt von ausgedehnten Luftschauern zu schätzen, indem es die Gesamtladung durch die eines durchschnittlichen Myons teilt. Zunächst beschreiben wir die aktuelle Kalibrierung für die SiPMs und wie der Arbeitspunkt des Zählermodus eingestellt wird. Unter Verwendung von Labordaten und Messungen des Observatoriums haben wir Studien durchgeführt, um die Stabilität der SiPM-Verstärkung bei Temperaturschwankungen zu bestätigen. Wir haben deren Rauschquellen gründlich charakterisiert. Dazu haben wir auch eine Myon-Zählstrategie vorgeschlagen, die das SiPM-Rauschen minimiert, ohne signifikant an Myonsignalen zu verlieren. Wir haben auch Daten aus dem Labor und dem Observatorium verwendet, um die Hauptmerkmale des Integrator-Modus zu extrahieren und ein Unsicherheitsmodell für die Signalladung zu erhalten. Zudem haben wir zwei mögliche Kalibrierungsverfahren für diesen Modus vorgestellt: das erste basiert auf Luftschauerereignissen, die offline durchgeführt werden können, und das zweite auf Hintergrunddaten, die online durchgeführt werden können. Außerdem wurden als Teil dieser Arbeit die AMIGA UMD-Simulationen entwickelt und in die Auger Datenanalyse- und Simulationssoftware ( Offline) implementiert. Der Code wurde mit Labordaten entwickelt und mit identischen Komponenten, wie die im UMD-Enddesign gemessen wurden, validiert. Sowohl analoge SiPM-Impulse als auch digitale Spuren nach der Frontend-Platine wurden erfasst und mit Simulationsergebnissen verglichen; erstere mit spezifischer Elektronik und letztere mit den gleichen elektronischen Bausätzen, die in der UMD-Produktion verwendet werden. Die Hauptmerkmale der Zähler- und Integratorkanäle sind relevant f”ur die Detektorleistung und werden hier diskutiert. Deren Unterschiede und Übereinstimmungen zwischen Simulations- und Labordaten werden dargestellt. Schließlich haben wir die neulich implementierten SiPM-Simulationen im Offline-Framework verwendet, um die Quellen systematischer Fehler des Zähler-Modus zu untersuchen und Korrekturen vorzuschlagen, die etwaige Rekonstruktionsverzerrungen beseitigen. Wir haben die Simulationen auch verwendet, um die Kalibrierung des Integratormodus zu testen und die Auflösungen beider Modii zu vergleichen. Wir haben diese Ergebnisse verwendet, um die Empfindlichkeit der UMD gegenüber der kosmischen Strahlungsprimärmasse zu untersuchen. Im Rahmen dieser Dissertation wurden mehrere Beiträge zum AugerPrime Upgrade erarbeitet. Unter anderem wurden: (i) Studien zur Bestätigung der Stabilität von SiPMs, (ii) die Prüfung und Abstimmung des SiPM-Kalibrierverfahrens und die Überprüfung seiner Robustheit, (iii) die Charakterisierung von UMD-Signalen und Rauschquellen, (iv) die Bestimmung der Effizienz und Dämpfung von Szintillatorstreifen mit eingebetteter Glasfaser (v) die Erreichung einer Zählstrategie zur Schätzung der Anzahl der Myonen in Luftschauern mit dem Counter-Modus, (vi) die Kalibrierung des Integratormodus unter Verwendung von Online- und Offline-Daten, (vii) das Design, die Entwicklung, die Implementierung und das Testen von SiPM- und elektronischen Simulationen, (viii) das Design, die Entwicklung, die Implementierung und das Testen der UMD-Ereignisvisualisierung in einer grafischen Benutzeroberfläche, (ix) Analysen über die Auswirkungen des Bodens bei der UMD-Rekonstruktion, (x) das Erreichen einer Rekonstruktionsverzerrungskorrektur für den Counter-Modus mit SiPMs, (xi) Analysen zur Verbesserung der UMD-Fähigkeiten zur Durchführung von Studien über die Zusammensetzung der kosmischen Strahlung, durchgeführt. Die in dieser Arbeit beschriebenen Werkzeuge und Methoden sind von größter Bedeutung für zukünftige Analysen mit dem unterirdischen AugerPrime Myonendetektor

    Distributed real-time hybrid simulation: Modeling, development and experimental validation

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    Real-time hybrid simulation (RTHS) has become a recognized methodology for isolating and evaluating performance of critical structural components under potentially catastrophic events such as earthquakes. Although RTHS is efficient in its utilization of equipment and space compared to traditional testing methods such as shake table testing, laboratory resources may not always be available in one location to conduct appropriate large-scale experiments. Consequently, distributed systems, capable of connecting multiple RTHS setups located at numerous geographically distributed facilities through information exchange, become essential. This dissertation focuses on the development, evaluation and validation of a new distributed RTHS (dRTHS) platform enabling integration of physical and numerical components of RTHS in geographically distributed locations over the Internet.^ One significant challenge for conducting successful dRTHS over the Internet is sustaining real-time communication between test sites. The network is not consistent and variations in the Quality of Service (QoS) are expected. Since dRTHS is delay-sensitive by nature, a fixed transmission rate with minimum jitter and latency in the network traffic should be maintained during an experiment. A Smith predictor can compensate network delays, but requires use of a known dead time for optimal operation. The platform proposed herein is developed to mitigate the aforementioned challenge. An easily programmable environment is provided based on MATLAB/xPC. In this method, (i) a buffer is added to the simulation loop to minimize network jitter and stabilize the transmission rate, and (ii) a routine is implemented to estimate the network time delay on-the-fly for the optimal operation of the Smith predictor.^ The performance of the proposed platform is investigated through a series of numerical and experimental studies. An illustrative demonstration is conducted using a three story structure equipped with an MR damper. The structure is tested on the shake table and its global responses are compared to RTHS and dRTHS configurations where the physical MR damper and numerical structural model are tested in local and geographically distributed laboratories.^ The main contributions of this research are twofold: (1) dRTHS is validated as a feasible testing methodology, alternative to traditional and modern testing techniques such as shake table testing and RTHS, and (ii) the proposed platform serves as a viable environment for researchers to develop, evaluate and validate their own tools, investigate new methods to conduct dRTHS and advance the research in this area to the limits

    Mapping parallelism to heterogeneous processors

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    Most embedded devices are based on heterogeneous Multiprocessor System on Chips (MPSoCs). These contain a variety of processors like CPUs, micro-controllers, DSPs, GPUs and specialised accelerators. The heterogeneity of these systems helps in achieving good performance and energy efficiency but makes programming inherently difficult. There is no single programming language or runtime to program such platforms. This thesis makes three contributions to these problems. First, it presents a framework that allows code in Single Program Multiple Data (SPMD) form to be mapped to a heterogeneous platform. The mapping space is explored, and it is shown that the best mapping depends on the metric used. Next, a compiler framework is presented which bridges the gap between the high -level programming model of OpenMP and the heterogeneous resources of MPSoCs. It takes OpenMP programs and generates code which runs on all processors. It delivers programming ease while exploiting heterogeneous resources. Finally, a compiler-based approach to runtime power management for heterogeneous cores is presented. Given an externally provided budget, the approach generates heterogeneous, partitioned code that attempts to give the best performance within that budget

    Development of tangible acoustic interfaces for human computer interaction

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    Tangible interfaces, such as keyboards, mice, touch pads, and touch screens, are widely used in human computer interaction. A common disadvantage with these devices is the presence of mechanical or electronic devices at the point of interaction with the interface. The aim of this work has been to investigate and develop new tangible interfaces that can be adapted to virtually any surface, by acquiring and studying the acoustic vibrations produced by the interaction of the user's finger on the surface. Various approaches have been investigated in this work, including the popular time difference of arrival (TDOA) method, time-frequency analysis of dispersive velocities, the time reversal method, and continuous object tracking. The received signal due to a tap at a source position can be considered the impulse response function of the wave propagation between the source and the receiver. With the time reversal theory, the signals induced by impacts from one position contain the unique and consistent information that forms its signature. A pattern matching method, named Location Template Matching (LTM), has been developed to identify the signature of the received signals from different individual positions. Various experiments have been performed for different purposes, such as consistency testing, acquisition configuration, and accuracy of recognition. Eventually, this can be used to implement HCI applications on any arbitrary surfaces, including those of 3D objects and inhomogeneous materials. The resolution with the LTM method has been studied by different experiments, investigating factors such as optimal sensor configurations and the limitation of materials. On plates of the same material, the thickness is the essential determinant of resolution. With the knowledge of resolution for one material, a simple but faster search method becomes feasible to reduce the computation. Multiple simultaneous impacts are also recognisable in certain cases. The TDOA method has also been evaluated with two conventional approaches. Taking into account the dispersive properties of the vibration propagation in plates, time-frequency analysis, with continuous wavelet transformation, has been employed for the accurate localising of dispersive signals. In addition, a statistical estimation of maximum likelihood has been developed to improve the accuracy and reliability of acoustic localisation. A method to measure and verify the dispersive velocities has also been introduced. To enable the commonly required "drag & drop" function in the operation of graphical user interface (GUI) software, the tracking of a finger scratching on a surface needs to be implemented. To minimise the tracking error, a priori knowledge of previous measurements of source locations is needed to linearise the state model that enables prediction of the location of the contact point and the direction of movement. An adaptive Kalman filter has been used for this purpose.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Development of tangible acoustic interfaces for human computer interaction

    Get PDF
    Tangible interfaces, such as keyboards, mice, touch pads, and touch screens, are widely used in human computer interaction. A common disadvantage with these devices is the presence of mechanical or electronic devices at the point of interaction with the interface. The aim of this work has been to investigate and develop new tangible interfaces that can be adapted to virtually any surface, by acquiring and studying the acoustic vibrations produced by the interaction of the user's finger on the surface. Various approaches have been investigated in this work, including the popular time difference of arrival (TDOA) method, time-frequency analysis of dispersive velocities, the time reversal method, and continuous object tracking. The received signal due to a tap at a source position can be considered the impulse response function of the wave propagation between the source and the receiver. With the time reversal theory, the signals induced by impacts from one position contain the unique and consistent information that forms its signature. A pattern matching method, named Location Template Matching (LTM), has been developed to identify the signature of the received signals from different individual positions. Various experiments have been performed for different purposes, such as consistency testing, acquisition configuration, and accuracy of recognition. Eventually, this can be used to implement HCI applications on any arbitrary surfaces, including those of 3D objects and inhomogeneous materials. The resolution with the LTM method has been studied by different experiments, investigating factors such as optimal sensor configurations and the limitation of materials. On plates of the same material, the thickness is the essential determinant of resolution. With the knowledge of resolution for one material, a simple but faster search method becomes feasible to reduce the computation. Multiple simultaneous impacts are also recognisable in certain cases. The TDOA method has also been evaluated with two conventional approaches. Taking into account the dispersive properties of the vibration propagation in plates, time-frequency analysis, with continuous wavelet transformation, has been employed for the accurate localising of dispersive signals. In addition, a statistical estimation of maximum likelihood has been developed to improve the accuracy and reliability of acoustic localisation. A method to measure and verify the dispersive velocities has also been introduced. To enable the commonly required "drag & drop" function in the operation of graphical user interface (GUI) software, the tracking of a finger scratching on a surface needs to be implemented. To minimise the tracking error, a priori knowledge of previous measurements of source locations is needed to linearise the state model that enables prediction of the location of the contact point and the direction of movement. An adaptive Kalman filter has been used for this purpose
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