Dissertations / Theses on the topic 'RPC DETECTOR'

Il Large Hadron Collider (LHC) è l’acceleratore per collisioni di ioni e protoni attualmente in costruzione al CERN di Ginevra. Questa macchina permetterà di raggiungere un’elevata energia nel centro di massa (14 TeV per collisioni protone-protone), dando la possibilità di produrre particelle con masse fino all’ordine del TeV. ATLAS è uno degli esperimenti di LHC. Una delle principali caratteristiche del rivelatore di ATLAS è di avere uno spettrometro per muoni in aria, che opera come un rivelatore a sé stante. Nel barrel il trigger di primo livello dei muoni è fornito dalle camere RPC (Resistive Plate Chambers): rivelatori a gas in grado di fornire una risposta veloce con un’eccellente risoluzione temporale (σt ≤1.5 ns). In questa tesi sono presentati i risultati del primo test di funzionamento di un intero settore del rivelatore a muoni, svoltosi al test-beam H8 del CERN. Particolare attenzione è data allo studio sistematico della “cluster size” delle camere RPC (il numero di strisce contigue accese, che sono associate ad uno stesso segnale nel rivelatore). Questo studio ha mostrato come la “cluster size” osservata, lungi dall’essere casuale, dipenda in modo sistematico dal punto di impatto della particella sul piano di strisce di lettura. Viene inoltre descritto il test sistematico, mediante raggi cosmici, di 192 camere RPC di produzione (tipo BOL), che è stato allestito presso il laboratorio INFN di Roma Tor Vergata. Questo lavoro, che ha richiesto una corposa acquisizione dati, ha fornito la necessaria base statistica per uno studio accurato della rate di rumore e delle correnti di gap, dimostrando uno standard di qualità nella produzione seriale molto superiore a quello dei prototipi. L’ampia mole di dati acquisiti fornisce inoltre l’informazione necessaria per progredire nella comprensione della fisica del rivelatore. Successivamente viene presentata una simulazione Monte Carlo (in GEANT4) della logica di trigger di livello-1 con muoni cosmici, orientata a studiare le possibili configurazioni del trigger così da massimizzare la rate con i raggi cosmici durante la fase di “commissioning” del rivelatore. E’ stata inoltre prodotta una simulazione limitata a sei torri del trigger, al fine di verificare l’accordo dei risultati ottenuti con le rate misurate durante il primo test di “commissioning” nella caverna di ATLAS, permettendo così per la prima volta di validare il programma di simulazione. Infine viene presentata l’analisi dei dati prodotti durante il test in caverna delle prime tre torri assemblate dello spettrometro a muoni.
The Large Hadron Collider (LHC) is the machine for proton and ion collisions in construction at CERN of Geneva. It will provide a very high energy in the center of mass, reaching the value of 14 TeV for proton-proton collisions, and giving the possibility to produce particles with mass up to few TeV. ATLAS is one of the LHC experiments. The ATLAS detector is characterized by its stand-alone Muon Spectrometer, based on an air-core toroid system, which generates a large field volume and a strong bending power with a light and open structure. In the barrel the ATLAS first level muon trigger relies on the Resistive Plate Chambers (RPC): these are gas ionization detectors which are characterized by a fast response and an excellent time resolution (σt ≤1.5 ns). A good understanding of the detector physics and a complete control of the performance are essential. For this purpose, a cosmic muon test stand has been built in the INFN Roma Tor Vergata Laboratory and a systematic test of the 192 biggest ATLAS RPCs was carried out. It consisted of a preliminary check of the detector status (gas-tightness and test of the electric circuits), and a characterization of every chamber: in particular the noise rate, the cluster size, the detection efficiency and the gap current have been studied for each detector. Moreover at H8 beam site at CERN, an ATLAS-like detector slice was assembled and tested with particle beams. The presence in the test of the tracking chambers (MDT), combined with the RPCs, allowed to the author an independent study of the RPC performances, exploiting the information extracted from the muon tracks reconstructed by the precision chambers. The assembly of the ATLAS detector in the cavern has already started and will be completed in almost one year. Then a phase of detector calibration and test will precede the beginning of the experiment, using the RPCs as trigger of cosmic rays. To optimize the selection of the cosmic muons, the author studied dedicated first level muon trigger configurations, using a Monte Carlo simulation (based on GEANT4). Although the ATLAS detector installation in the cavern is still undergoing, some subdetectors are already operative: three muon stations of the lowest sector are ready and working. This allowed to validate the trigger simulation and furthermore to start the muon station debugging.

Orientador: Anderson Campos Fauth
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Apresentamos um estudo sobre detectores a gás do tipo Resistive Plate Counter - RPC e sobre a viabilidade de sua utilização em experimentos de física de raios cósmicos. Discutimos os processos de formação e leitura do sinal quando da passagem de uma partícula ionizante pela região ativa do detector e apresentamos os resultados experimentais relevantes: espectros de carga, eficiência, contagem e resolução temporal. Obtivemos uma eficiência de 85 % e uma resolução temporal de 4ns, suficiente para a realização de medidas de 'tempo de vôo'. Os RPCs estudados foram construídos no Laboratório de Léptons do Instituto de Física Gleb Wataghin, Unicamp, a partir de componentes nacionais disponíveis no mercado. A modularidade dos RPCs e seu baixo custo sugerem que esses detectores são apropriados para experimentos de raios cósmicos, onde grandes áreas de detecção estão envolvidas
Abstract: We present a study about Resistive Plate Counters and the viability of their use in cosmic ray experiments. The processes of discharge formation by an ionizing particle and signal pick up are discussed, and the relevant experimental results ¿ charge spectra, efficiency, counting rates and time resolution are shown. An efficiency of 85 % and a time resolution of 4 ns, suitable for time of flight measurements, were achieved. The studied RPCs were assembled with brazilian commercially available materials at the Leptons Laboratory of the Gleb Wataghin Physics Department, Unicamp. The RPC's low cost and high modularity suggest their use in cosmic ray experiments, in which large detection areas are required.
Mestrado
Física
Mestre em Física

Este trabalho propõe um método biotelemétrico para a determinação simultânea de duas características elétricas (moduláveis por parâmetros fisiológicos) de circuitos RLC passivos para microsensores injetáveis. Como o ambiente sob monitoração envolve a presença de íons (tecidos biológicos), a utilização de dipolos torna-se inviável, desta forma, o estabelecimento de um acoplamento indutivo entre o sensor e o dispositivo para o registro das medidas é necessário. Tratando-se de um dispositivo injetável, as dimensões da bobina do sensor são diminutas (diâmetro da ordem de mm), sugerindo cuidados especiais quanto ao acoplamento indutivo do circuito RLC com o dispositivo de registro das medidas. Desta forma, foi desenvolvido um detector digital de freqüências, associado a um conjunto otimizado de bobinas para obter, a determinada distância (5 mm), a melhor indutância mútua possível com o microcircuito RLC remoto. Este dispositivo monitora o sensor em tempo real, informando a freqüência de ressonância, a sua respectiva amplitude a partir de uma varredura em freqüência. Um estudo analítico modelando a resposta em tensão do circuito detector segundo os estímulos e respostas que este fornece e recebe do circuito RLC remoto foi desenvolvido. O resultado desta análise, verificada praticamente, possibilitou a identificação da constante de tempo que cada degrau de freqüência deve ser mantido no sensor para que a resposta indicada seja a mais precisa possível. Decorrente desta análise foi possível modelar teoricamente a resistência total que o circuito RLC remoto apresenta. Assim, a partir das medidas de freqüência e amplitude do detector e do modelo teórico da resistência total do sensor o método foi estabelecido. Para verificar na prática a validade do método um micro sensor (2,8 x 23 mm) foi desenvolvido. O sensor foi encapsulado dentro de um tubo de silicone, apresentando um indutor montado junto a um bastão de ferrite, um capacitor SMD e um NTC, todos associados em paralelo. Com a alteração da distância entre o bastão de ferrite e o indutor (através da tração do tubo de silicone) a freqüência do sensor é alterada e a variação da resistência do NTC, através da temperatura, altera o fator de qualidade do sensor. A utilização do método para monitorar o sensor apresentou erros inferiores a 0,57 % para a indicação da freqüência e 0,77 % para a indicação da temperatura. A influência medida da variação da temperatura sobre a indicação da freqüência foi inferior a 0,16 %, indicando que o método é viável.
This work proposes a biotelemetric method to determine simultaneously two electrical characteristics (modulated by physiological parameters) from a passive injectable RLC microcircuit. Due to the presence of free ions inside the biological tissue, inductive links (loop antennas) must be employed, instead of dipole antennas. As the coil of the sensor presents small dimensions (diameter of about mm) its magnetic coupling to the monitoring device requires special attention. To monitor the sensor, a digital device assembled with a group of coils to maximize the mutual inductance (at a distance of 5 mm) between them was developed, detecting its resonance frequencies and the respective amplitude (through a frequency sweep) in real-time. The electrical response acquired by the detector from the sensor was analytically modeled. The model indicates a time constant to consider for each change of the signal frequencies to prevent errors in the response. From that theoretical model, an equation to determine the total resistance from the RLC circuit was obtained and confirmed by experiments. Then, a method to determine the resonance frequency and the total resistance from remote RLC circuit was proposed. A sensor was developed to verify the accuracy and the limits from this method. A parallel RLC circuit was built inside a silicone rubber tube. When the tube is stretched, a ferrite rod assembled beside the inductor is displaced varying the resonance frequency and, changing the environmental temperature, a NTC varies the quality factor of the circuit. Tests using the proposed method to monitor the sensor were realized. Errors small than 0.57 % in the resonance frequencies and 0.77 % in the temperature were obtained. The measured influence of the temperature variation over frequency determination was less than 0.16 %, indicating that the method is feasible.

The focus of this thesis is the development of Resistive Plate Chambers (RPCs) with ceramic electrodes. The use of ceramic composites, Si3N4/SiC, opens the way for the application of RPCs in harsh radiation environments. Future Experiments like the Compressed Baryonic Matter (CBM) at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt will need new RPCs with high rate capabilities and high radiation tolerance. Ceramic composites are specially suited for this purpose due to their resistance to radiation and chemical contamination. The bulk resistivity of these ceramics is in the range 10^7 - 10^13 Ohm cm. The bulk resistivity of the electrodes is the main factor determining the rate capabilities of a RPC, therefore a specifific measuring station and a measurement protocol has been set for these measurements. The dependence of the bulk resistivity on the difffferent steps of the manufacturing process has been studied. Other electrical parameters like the relaxation time, the relative permittivity and the tangent loss have also been investigated. Simulation codes for the investigation of RPC functionality was developed using the gas detectors simulation framework GARFIELD++. The parameters of the two mixtures used in RPC operation have been extracted. Furthermore, theoretical predictions on time resolution and effi ciency have been calculated and compared with experimental results. Two ceramic materials have been used to assemble RPCs. Si3N4/SiC and Al2O3 with a thin (nm thick) chromium layer deposited over it. Several prototypes have been assembled with active areas of 5x 5 cm^2, 10x 10 cm^2 and 20 x20 cm^2. The number of gaps ranges from two to six. The gas gap widths were 250 micro meter and 300 micrometer. As separator material mylar foils, fifishing line and high-resistive ceramics have been used. Different detector architectures have been built and their effffect on RPC performance analysed. The RPCs developed at HZDR and ITEP (Moscow) were systematically tested in electron and proton beams and with cosmic radiation over the course of three years. The performance of the RPCs was extracted from the measured data. The main parameters like time resolution, effi ciency, rate capabilities, cluster size, detector currents and avalanche charge were obtained and compared with other RPC systems in the world. A comparison with phenomenological models was performed.

Thesis (MMed)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Background Occult blood loss from the gastrointestinal tract (GIT), causing iron deficiency often with anaemia, can be diagnostically and therapeutically challenging. This is because the endoscopic and radiologic tests may be negative due to the slow, chronic and intermittent nature of the gastrointestinal bleeding, making timing key in detection and localisation of the bleed. These limitations can be approached using two different radioactive isotopes. Firstly, we tested the sensitivity of extending Cr-51 RBC for 21 days relative to 5 days to detect GIT bleeding and its use to optimise timing of a Tc-99m RBC study for GIT blood loss localisation. Finally, we tested if the information provided by the Tc-99m RBC study aided gastroenterologic intervention for anatomical localisation of a lesion. Method In this retrospective review, after obtaining institutional and ethics committee approval, records of patients referred for evaluation of possible GIT blood loss were reviewed. In each; daily appearance of radiochromium in stool was measured in the whole body counter. In those cases exceeding 50 ml/day, a technetium-99m (Tc-99m) localization study was performed. These studies were correlated with clinical findings. Results A total of 59 Cr-51 RBC studies were carried out in 36 females and 21 males (n = 57). In 32 (54%) the radiochromium results were positive with 75% of the bleeding incidences occurring after 5 days of stool collection. Of 17 cases in whom Tc-99m RBC imaging studies were performed, 14 (82%) were positive with specific anatomical sites successfully defined in twelve. In all patients with blood loss of >100 ml/24h, Tc-99m RBC were positive and localised. Ten of the 17 Tc-99m RBC studies were further investigated and half diagnosed with small-bowel angiodysplasia. Conclusion This sequential twin isotope method is practical in revealing otherwise silent intestinal haemorrhage. Although it has good patient acceptability and clinical as well as diagnostic utility in management, further studies are required to clearly establish a cut-off level of blood loss for performing imaging studies and the impact of the findings on the overall patient management.
AFRIKAANSE OPSOMMING: Agtergrond Die evaluasie van okkulte bloedverlies uit die gastro-intestinale kanaal (GIT), met gevolglike ystertekort anemie, kan diagnosties en terapeuties uitdagend wees. Dit is omdat endoskopiese en radiologiese ondersoeke negatief mag wees as gevolg van die stadige, chroniese en intermitterende aard van die gastro-intestinale bloeding, wat die presiese tydstip van opsporing en lokalisering van die bloeding krities belangrik maak. Hierdie beperkings kan aangespreek word deur twee verskillende radioaktiewe isotope te gebruik. Eerstens is die sensitiwiteit van die verlenging van die Cr-51 RBS studie tot 21 dae in plaas van 5 dae om die GIT bloeding op te spoor, getoets, asook die gebruik daarvan om die optimale tyd vir ‘n Tc-99m RBS studie om die GIT bloedverlies te lokaliseer, vas te stel. Laastens is getoets of die inligting van die Tc-99m RBS studie wel bygedra het tot die gastroenterologiese ingreep om die letsel anatomies te lokaliseer. Metode Na institusionele en etiese komitee toestemming is inligting van pasiënte wat vir die evaluering van ‘n moontlike GI bloedverlies verwys is, in hierdie retrospektiewe oorsig nagegaan. Die daaglikse voorkoms van radioaktiewe chroom in stoelgangmonsters is in ‘n heelliggaamteller gemeet. In gevalle waar dit 50 ml/dag oorskry het, is ‘n tegnesium 99m (Tc 99m) studie gedoen. Hierdie studies is met die kliniese bevindinge gekorreleer. Resultate ‘n Totaal van 59 Cr-51 RBS studies is in 36 vroue en 21 mans (n = 57) gedoen. Die gemerkte chroomstudies was positief in 32 (54%), met 75% van die bloedings wat meer as 5 dae na versameling van die stoelgang plaasgevind het. In veertien (82%) van die 17 gevalle waar Tc-99m RBS studies gedoen is, was die studies positief. Spesifieke anatomiese gebiede van bloeding kon in 12 hiervan suksesvol bevestig word. Tc-99m RBS studies was positief in al die pasiënte met ‘n bloedverlies van >100 ml/24h, en kon gelokaliseer word. Tien van die 17 Tc-99m RBS studies is verder ondersoek en die helfte daarvan gediagnoseer met dunderm angiodisplasie. Gevolgtrekking Die opeenvolgende twee isotoopmetode om andersins asimptomatiese dermbloeding op te spoor, is prakties uitvoerbaar. Alhoewel die studies goed deur pasiënte aanvaar is, en ook van kliniese en diagnostiese waarde in die hantering van die pasiënte is, is verdere studies nodig om die afsnypunt vir die hoeveelheid bloedverlies om beeldingstudies uit te voer, sonder twyfel vas te stel, asook om die impak van die bevindings op ‘n groter pasiëntpopulasie vas te stel.

When studying detection systems, parameters associated with the Receiver Operating Characteristic (ROC) curve are often estimated to assess system performance. In some applied settings it is often not possible to test the detection system with large numbers of stimuli. The resulting small sample statistics many have undesirable properties. The characteristics of these small sample ROC estimators were examined in a Monte Carlo simulation. Three popular ROC parameters were chosen for study. One of the parameters was a single parameter index of system performance, Area under the ROC curve. The other parameters, ROC intercept and slope, were considered as a pair. ROC intercept and slope were varied along with sample size and points on the certainty rating scale to form a four way factorial design. Several types of estimators were examined. For the parameter, Area under the curve, Maximum Likelihood (ML), three types of Least Squares (LS), and Distribution Free (DF) estimators were considered. Except for the DF estimator, the same estimators were considered for the parameters, intercept and slope. These estimators were compared with respect to three characteristics: bias, efficiency, and consistency. For Area under the curve, the ML estimator was the least biased. The DF estimator was the most efficient, and all the estimators except the DF estimator appeared to be consistent. For intercept and slope the LS estimator that minimized vertical error of the points from the ROC curve (line) was the least biased for both estimators. This LS estimator was also the most efficient. This estimator along with the ML estimator also appeared to be the most consistent. The other two estimators had no significant trend toward consistency. These results along with other findings, illustrate that different estimators may be "best" for different sample sizes and for different parameters. Therefore, researchers should carefully consider the characteristics of ROC estimators before using them as indices of system performance.

Avui en dia, hi ha la necessitat de desenvolupar un sistema per a la detecció d'ADN que sigui ràpid, simple, econòmic i reproduïble per al diagnòstic en diferents camps com malalties genètiques, detecció de patògens, medicina forense i medicina personalitzada.Els mètodes convencionals per a la detecció de seqüències d'ADN específiques es basen en assajos de seqüenciació directa o d'hibridació, essent aquest últim el més utilitzat en genosensors. Aquest mètode consisteix en l'ús de superfícies transductores modificades amb sondes d'ADN monocatenari, que reconeixen la seva seqüència complementària (diana) amb alta afinitat i especificitat.Una de les limitacions de l'aplicació d'aquests sensors a dispositius portàtils és la necessitat de la realització d'etapes posteriors a l'amplificació. Aquestes etapes inclouen la generació d'ADN monocatenari o la seva modificació amb un marcador abans de assolir la detecció.En aquest treball, es combina l'amplificació isotèrmica i l'ús d'encebadors modificats per simplificar les etapes necessàries per la detecció electroquímica d'ADN. Aquests encebadors, contenen una seqüència d'oligonucleòtids monocatenària unida a un espaiador de carboni, que bloqueja eficaçment l'elongació, abans de la seqüència del encebador. Per tant, el producte final està compost per un ADN de doble cadena flanquejat per dues cues d'ADN monocatenàries. Una de les cues es va utilitzar per hibridar a una sonda immobilitzada en la superfície i l'altra a una sonda marcada amb enzims o nanopartícules d'or. L'ús d'aquests encebadors modificats van permetre detectar l’ADN electroquímicament sense necessitat d'un tractament posterior a l'amplificació de la mostra, disminuint el temps d'assaig i presentant un enfocament més portable per ser aplicat en qualsevol situació.
Hoy en día, existe la necesidad de desarrollar un sistema para la detección de ADN que sea rápido, simple, económico y reproducible para el diagnóstico en diferentes campos como enfermedades genéticas, detección de patógenos, medicina forense y medicina personalizada.Los métodos convencionales para la detección de secuencias de ADN específicas se basan en ensayos de secuenciación directa o de hibridación, siendo este último el más utilizado en genosensores. Este método consiste en el uso de superficies transductoras modificadas con sondas de ADN monocatenario (ssDNA), que reconocen su secuencia complementaria (diana) con alta afinidad y especificidad.Una de las limitaciones de la aplicación de estos sensores a dispositivos portátiles es la necesidad de la realización de etapas posteriores a la amplificación. Estas etapas incluyen la generación de ADN monocatenario o su modificación con un marcador antes de pasar a la detección.En este trabajo, se combina la amplificación isotérmica y el uso de cebadores modificados para simplificar los pasos necesarios para la detección electroquímica de ADN. Estos cebadores, contienen una secuencia de oligonucleótidos monocatenaria unida a un espaciador de carbono, que bloquea eficazmente la elongación, antes de la secuencia del cebador. Por lo tanto, el producto final está compuesto por un ADN de doble cadena flanqueado por dos colas de ADN monocatenarias. Una de las colas se usó para hibridar a una sonda inmovilizada en la superficie y la otra a una sonda marcada con enzimas o nanopartículas de oro. El uso de estos cebadores modificados permitió detectar ADN electroquímicamente sin necesidad de un tratamiento posterior a la amplificación de la muestra, disminuyendo el tiempo de ensayo y presentando un enfoque más portable para ser aplicado en cualquier situación
Nowadays, there is a need to develop a rapid, simple, inexpensive and reliable DNA testing system for diagnosis in different fields such as genetic diseases, pathogens detection, forensics, and personalised medicine. Conventional methods for the detection of specific DNA sequences are based on direct sequencing or hybridisation assays, being this last one approach, the most widely used in genosensors. It consists on single-stranded DNA (ssDNA) tethered probes on a transducer surface, which recognises its complementary sequence (target) with high affinity and specificity. One of the limitations of these DNA sensors to apply them for a portable molecular diagnostics devices is the multi-step procedures needed, since post-amplification treatment is necessary for its detection by generating ssDNA or adding a hapten labelling. In this work, the isothermal amplification and modified tailed primers to simplify the steps required for the electrochemical DNA detection are combined. Modified tailed primers are based on a single stranded oligonucleotide sequence linked to a carbon spacer, which effectively blocks elongation, prior to the primer sequence. Thus, resulting in an amplicon with a duplex flanked by two single stranded DNA tails. One of the tails was used to hybridise to a surface immobilised probe and the other to an enzyme or gold nanoparticles labelled reporter probe. Using these modified primers allowed us to detect DNA electrochemically without any need for post-amplification sample treatment decreasing the assay time and presenting an approach that can facilely find application at the point of need.

L'objectiu general d'aquesta tesi doctoral és desenvolupar plataformes de geno-sensors de baix cost per a la detecció múltiple de polimorfismes d'un sol nucleòtid. La determinació de polimorfismes d'un sol nucleòtid (SNP) és de gran importància en les ciències de la vida, tenint aplicació en la medicina personalitzada, estratificació de pacients, forense, a més de brindar informació sobre la predisposició a la malaltia. En l'actualitat, els mètodes basats en l'electroquímica es revelen com alternatives atractives a les tècniques més utilitzades per determinar el punt de fusió de l'ADN, per la seva alta sensibilitat, simplicitat, rendibilitat i compatibilitat amb la microfabricació. La primera plataforma es va basar en una reacció d'extensió d'encebadors electroquímics, on els polioximetalats actius redox de Keggin i Dawson es van utilitzar per modificar dideoxinucleótids a través de la formació d'enllaços amida. La segona plataforma es basa en la detecció de polimorfismes d'un sol nucleòtid mitjançant l'anàlisi electroquímic de la corba de desnaturalització. L'enfocament es basa en l'anàlisi de la corba de desnaturalització en fase sòlida que utilitza sondes immobilitzades en elèctrodes d'or. Es va desenvolupar un prototip de dispositiu capaç de detectar un ADN diana que porta un SNP relacionat amb la miocardiopatia amb una sola base en la diferència. Finalment, aquest dispositiu es va aplicar a la detecció de SNP en mostres de sang reals. La diana de seqüència de SNP relacionada amb l'osteoporosi es va extreure d'una punxada al dit i es va amplificar usant PCR asimètrica. A més, es van optimitzar les condicions d'amplificació per obtenir el millor rendiment del producte i es va definir l'SNP d'una mostra de sang.
El objetivo general de esta tesis doctoral es desarrollar plataformas de geno-sensores de bajo costo para la detección múltiple de polimorfismos de un solo nucleótido. La determinación de polimorfismos de un solo nucleótido (SNP) es de gran importancia en las ciencias de la vida, teniendo aplicación en la medicina personalizada, estratificación de pacientes, forense, además de brindar información sobre la predisposición a la enfermedad. En la actualidad, los métodos basados en la electroquímica se revelan como alternativas atractivas a las técnicas más utilizadas para determinar el punto de fusión del ADN, debido a su alta sensibilidad, simplicidad, rentabilidad y compatibilidad con la microfabricación. La primera plataforma se basó en una reacción de extensión de cebadores electroquímicos, donde los polioximetalatos activos redox de Keggin y Dawson se utilizaron para modificar didesoxinucleótidos a través de la formación de enlaces amida. La segunda plataforma se basa en la detección de polimorfismos de un solo nucleótido mediante el análisis electroquímico de la curva de desnaturalización. El enfoque se basa en el análisis de la curva de desnaturalización en fase sólida que utiliza sondas inmovilizadas en electrodos de oro. Se desarrolló un prototipo de dispositivo capaz de detectar un ADN diana que porta un SNP relacionado con la miocardiopatía con una sola base en la diferencia. Finalmente, este dispositivo se aplicó a la detección de SNP en muestras de sangre reales. La diana de secuencia de SNP relacionada con la osteoporosis se extrajo de un pinchazo en el dedo y se amplificó usando PCR asimétrica. Además, se optimizaron las condiciones de amplificación para obtener el mejor rendimiento del producto y se definió el SNP de una muestra de sangre.
The overall objective of this PhD thesis is to develop low cost geno-sensor platforms for multiplexed detection of single nucleotide polymorphism. The determination of single nucleotide polymorphisms (SNP) is of great importance in life sciences, having application in personalised medicine, patient stratification, forensics, as well as providing information regarding predisposition to disease. Nowadays electrochemistry-based methods are revealed as attractive alternatives to the most commonly used techniques for determining DNA melting point, because of their high sensitivity, simplicity, cost-effective and compatibility with microfabrication. The first platform was based on an electrochemical primer extension reaction, where the redox active Keggin and Dawson polyoxymetalates were used to modify dideoxynucleotides through amide bond formation. The second platform is based on the detection of single nucleotide polymorphisms using electrochemical melting curve analysis. The approach is based on solid phase melting curve analysis that exploits probes immobilised on gold electrodes. We developed a home-made electrochemical melting curve analysis device, able to detect a DNA target that carries a SNP related to cardiomyopathy from others with only one base in difference. Finally, this device was applied to SNPs detection in real blood samples. Osteoporosis related SNP sequence target was extracted from a finger prick and amplified using asymmetric Recombinase Polymerase Amplification. Also, the amplification conditions were optimised for best product yield, and the SNP from a blood sample was defined.

This diploma thesis deals with pause identification with degraded speech signal. The speech characteristics and the conception of speech signal processing are described here. The work aim was to create the reliable recognizing method to establish speech and non-speech segments of speech signal with and without degraded speech signal. The five empty pause detectors were realized in computing environment MATLAB. There was the energetic detector in time domain, two-step detector in spectral domain, one-step integral detector, two-step integral detector and differential detector in cepstrum. The spectral detector makes use of energetic characteristics of speech signal in first step and statistic analysis in second step. Cepstral detectors make use of integral or differential algorithms. The detectors robustness was tested for different types of speech degradation and different values of Signal to Noise Ratio. The test of influence different speech degradation was conducted to compare non-speech detection for detectors by ROC (Receiver Operating Characteristic) Curves.

Locating and extracting useful data from images is a task that has been revolutionized in the last decade as computing power has risen to such a level to use deep neural networks with success. A type of neural network that uses the convolutional operation called convolutional neural network (CNN) is suited for image related tasks. Using the convolution operation creates opportunities for the network to learn their own filters, that previously had to be hand engineered. For locating objects in an image the state-of-the-art Faster R-CNN model predicts objects in two parts. Firstly, the region proposal network (RPN) extracts regions from the picture where it is likely to find an object. Secondly, a detector verifies the likelihood of an object being in that region.For this thesis, we review the current literature on artificial neural networks, object detection methods, proposal methods and present our new way of generating proposals. By replacing the RPN with our network, the multiscale proposal network (MPN), we increase the average precision (AP) with 12% and reduce the computation time per image by 10%.
Lokalisering av användbar data från bilder är något som har revolutionerats under det senaste decenniet när datorkraften har ökat till en nivå då man kan använda artificiella neurala nätverk i praktiken. En typ av ett neuralt nätverk som använder faltning passar utmärkt till bilder eftersom det ger möjlighet för nätverket att skapa sina egna filter som tidigare skapades för hand. För lokalisering av objekt i bilder används huvudsakligen Faster R-CNN arkitekturen. Den fungerar i två steg, först skapar RPN boxar som innehåller regioner där nätverket tror det är störst sannolikhet att hitta ett objekt. Sedan är det en detektor som verifierar om boxen är på ett objekt .I denna uppsats går vi igenom den nuvarande litteraturen i artificiella neurala nätverk, objektdektektering, förslags metoder och presenterar ett nytt förslag att generera förslag på regioner. Vi visar att genom att byta ut RPN med vår metod (MPN) ökar vi precisionen med 12% och reducerar tiden med 10%.

Anomaly detection in time series is a broad field with many application areas, and has been researched for many years. In recent years the need for monitoring and DevOps has increased, partly due to the increased usage of microservice infrastructures. Applying time series anomaly detection to the metrics emitted by these microservices can yield new insights into the system health and could enable detecting anomalous conditions before they are escalated into a full incident. This thesis investigates how two proposed anomaly detectors, one based on the RPCA algorithm and the other on the HTM neural network, perform on metrics emitted by a microservice infrastructure, with the goal of enhancing the infrastructure monitoring. The detectors are evaluated against a random sample of metrics from a digital rights management company’s microservice infrastructure, as well as the open source NAB dataset. It is illustrated that both algorithms are able to detect every known incident in the company metrics tested. Their ability to detect anomalies is shown to be dependent on the defined threshold value for what qualifies as an outlier. The RPCA Detector proved to be better at detecting anomalies on the company microservice metrics, however the HTM detector performed better on the NAB dataset. Findings also highlight the difficulty of manually annotating anomalies even with domain knowledge. An issue found to be true for both the dataset created for this project, and the NAB dataset. The thesis concludes that the proposed detectors possess different abilities, both having their respective trade-offs. Although they are similar in detection accuracy and false positive rates, each has different inert abilities to perform tasks such as continuous monitoring or ease of deployment in an existing monitoring setup.
Anomalitetsdetektering i tidsserier är ett brett område med många användningsområden och har undersökts under många år. De senaste åren har behovet av övervakning och DevOps ökat, delvis på grund av ökad användning av microservice-infrastrukturer. Att tillämpa tidsserieanomalitetsdetektering på de mätvärden som emitteras av dessa microservices kan ge nya insikter i systemhälsan och kan möjliggöra detektering av avvikande förhållanden innan de eskaleras till en fullständig incident. Denna avhandling undersöker hur två föreslagna anomalitetsdetektorer, en baserad på RPCA-algoritmen och den andra på HTM neurala nätverk, presterar på mätvärden som emitteras av en microservice-infrastruktur, med målet att förbättra infrastrukturövervakningen. Detektorerna utvärderas mot ett slumpmässigt urval av mätvärden från en microservice-infrastruktur på en digital underhållningstjänst, och från det öppet tillgängliga NAB-dataset. Det illustreras att båda algoritmerna kunde upptäcka alla kända incidenter i de testade underhållningstjänst-mätvärdena. Deras förmåga att upptäcka avvikelser visar sig vara beroende av det definierade tröskelvärdet för vad som kvalificeras som en anomali. RPCA-detektorn visade sig bättre på att upptäcka anomalier i underhållningstjänstens mätvärden, men HTM-detektorn presterade bättre på NAB-datasetet. Fynden markerar också svårigheten med att manuellt annotera avvikelser, även med domänkunskaper. Ett problem som visat sig vara sant för datasetet skapat för detta projekt och NAB-datasetet. Avhandlingen slutleder att de föreslagna detektorerna har olikaförmågor, vilka båda har sina respektive avvägningar. De har liknande detekteringsnoggrannhet, men har olika inerta förmågor för att utföra uppgifter som kontinuerlig övervakning, eller enkelhet att installera i en befintlig övervakningsinstallation.

La neumonía es la principal causa de muerte en niños menores de 5 años en el mundo. Se calculan más muertes por neumonía que por VIH, malaria y sarampión. Considerando la alta tasa de mortandad infantil por neumonía; el objetivo principal de este proyecto de tesis, fue diseñar e implementar un prototipo electrónico para detección temprana contra la neumonía en infantes. Para este propósito, se usó un sensor de temperatura, el LM35, el cual se adaptó a un electrodo médico, de esta manera fue adherido al cuerpo del paciente, además se usó un sensor magnético adaptado a una banda elástica, la cual se colocó alrededor del tórax del paciente. Estos sensores midieron la temperatura corporal en °C y el número de respiraciones por minuto (RPM), respectivamente. Ambas mediciones se acondicionaron, usando el amplificador operacional LM358N y se procesaron usando un Microcontrolador PIC16F877A. Los datos procesados pasaron a una PC mediante una interface de comunicación USB. Previamente en la PC se cargó una aplicación informática escrita y desarrollada en Visual Basic, la cual contó con una interface gráfica, donde se visualizó el resultado de la prueba. Las pruebas se hicieron con siete niños de diferentes edades, de los cuales mencionaremos solo a tres. La cuarta prueba se realizó con un niño de 2 años de edad, obteniendo como resultado una temperatura corporal de 39°C, 37 RPM y como diagnóstico, la temperatura corporal es excesiva y próxima a taquipnea. La quinta prueba se realizó con una niña de cuatro años de edad, obteniendo como resultado una temperatura corporal de 39°C, 31 RPM y como diagnóstico, la temperatura corporal es excesiva y próxima a taquipnea. La séptima prueba se realizó en una niña de 1 año de edad, obteniendo como resultado una temperatura corporal de 39°C, 34 RPM y como diagnóstico, la temperatura corporal es excesiva y próxima a taquipnea, siendo estas las condiciones necesarias para prevenir de forma temprana la neumonía como lo indica en su opinión la profesional médico a la que recurrimos. Estos resultados mostraron que el prototipo logró el objetivo principal, al diseñar un equipo de prevención contra la neumonía. Pneumonia is the main cause of death in children under five years old, in the world. More deaths are estimated by pneumonia than HIV, malaria and measles. According to the high infant mortality rate from pneumonia; the main target of this thesis is design and implement an electronic prototype for early detection pneumonia in infants. For this purpose, I use a temperature sensor, the LM35, which was adapted to a medical electrode, in this way was attached to the patient’s body, also I use a magnetic sensor adapted to a rubber band, which was placed around the patient's chest. These sensors measure the body temperature in °C and the number of breaths per minute (BPM), respectively. Both measurements were conditioned using the LM358N operational amplifier and processed using a PIC16F877A microcontroller. Data processed are transferred to a PC by an USB communication interface. Previously, in a Desktop computer was installed a software application developed in Visual Basic, which it has a graphical interface and test’s result is visualized. The tests were performed with seven children of different ages, of which I will mention only three cases. The fourth test was performed with a two years old boy, resulting in a body temperature of 39 °C, 37 BPM and as a diagnostic, body temperature is over and close to tachypnea. The fifth test was performed with a four years old boy, resulting in a body temperature of 39 °C, 31 BPM and as a diagnostic, body temperature is over and close to tachypnea. The seventh test was performed on a baby girl of 1 year old, resulting in a body temperature of 39 °C, 34 BPM and as a diagnostic, body temperature is over and close to tachypnea, focusing on these results, these are the necessary conditions to prevent such early pneumonia according to opinion of professional medical that support me. These results showed that the prototype achieved the main objective, to design a prevention equipment against pneumonia.

Functional Magnetic Resonance Imaging (fMRI) is a neuroimaging technique used to study brain functionality to enhance our understanding of the brain. This technique is based on MRI, a painless, noninvasive image acquisition method without harmful radiation. Small local blood oxygenation changes which are reflected as small intensity changes in the MR images are utilized to locate the active brain areas. Radio frequency pulses and a strong static magnetic field are used to measure the correlation between the physical changes in the brain and the mental functioning during the performance of cognitive tasks.

This master thesis presents approaches for the analysis of fMRI data. The constrained Canonical Correlation Analysis (CCA) which is able to exploit the spatio-temporal nature of an active area is presented and tested on real human fMRI data. The actual distribution of active brain voxels is not known in the case of real human data. To evaluate the performance of the diagnostic algorithms applied to real human data, a modified Receiver Operating Characteristics (modified ROC) which deals with this lack of knowledge is presented. The tests on real human data reveal the better detection efficiency with the constrained CCA algorithm.

A second aim of this thesis was to implement the promising technique of constrained CCA into the software environment SPM. To implement the constrained CCA algorithms into the fMRI part of SPM2, a toolbox containing Matlab functions has been programmed for the further use by neurological scientists. The new SPM functionalities to exploit the spatial extent of the active regions with CCA are presented and tested.

L'objectiu principal d’aquesta tesis és desenvolupar sensors d’ADN portàtils i fàcils d’utilitzar per analitzar material genètic al lloc on sigui necessari, superant les limitacions de les tecnologies actuals. Per dur-ho a terme, els sensors d’ADN s’han dissenyat integrant en un únic dispositiu dues tecnologies: l’amplificació isotèrmica d’ADN, tant en fase líquida com en fase sòlida, i la tecnologia de microarrays. A la tesis es detallen els resultats obtinguts per assolir els objectius específics, que inclouen: el desenvolupament d’una plataforma d’anàlisi d’ADN en fase líquida per a la detecció simultània de diversos organismes. L’ús d’amplificació isotèrmica d’ADN en superfície (fase sòlida), combinant tant amb detecció òptica com detecció electroquímica per a la detecció de mostres reals. L’estudi i optimització de la química de superfície dels sensors d’ADN en fase sòlida, i finalment, l’amplificació isotèrmica d’ADN d’algues tòxiques emprant dNTPs modificats amb molècules redox, fet que permet mesurar directament l’ADN amplificat reduint el temps total d’anàlisi.
El objetivo principal de la tesis es desarrollar sensores de ADN portátiles y fáciles de utilizar para analizar material genético allí donde sea requerido, superando las limitaciones de las tecnologías actuales. Para llevarlo a cabo, los sensores de ADN se han diseñado integrando en un único dispositivo dos tecnologías: la amplificación isotérmica de ADN tanto en fase líquida como en fase sólida, y la tecnología de microarrays. En la tesis se detallan los resultados obtenidos para lograr los objetivos específicos, que incluyen: el desarrollo de una plataforma de análisis de ADN en fase líquida para la detección simultánea de distintos organismos. El uso de amplificación isotérmica de ADN en superficie (fase sólida) combinado tanto con detección óptica como con detección electroquímica para la detección de muestras reales. El estudio y optimización de la química de superficie de los sensores de ADN en fase sólida, y finalmente, la amplificación isotérmica de ADN de algas tóxicas utilizando dNTPs modificados con moléculas redox, cosa que permite medir el ADN amplificado directamente, reduciendo así el tiempo tota de análisis.
The main goal of this doctoral thesis is to present alternative approaches in the field of DNA biosensors, design and develop new isothermal amplification protocols compatible with a portable, easy-to use device that can be deployed for analysis of genetic material at the point-of-care/need, while overcoming some of the currently existing limitations. In order to achieve this objective, a variety of different strategies of effective solid-phase immobilisation and liquid-phase and solid-phase isothermal enzymatic amplification have been studied to achieve lower detection limits with rapid and easy to carry out assays. This work presents a convenient, flexible solution for detecting DNA with biosensors, exploiting a general concept of liquid-phase and solid-phase isothermal amplification and detection, thus integrating two nucleic acid tests, PCR and microarrays, in one single device. The thesis report the work performed to achieve the specific objectives of this doctoral thesis: the development of multiplexing platform for simultaneous detection of several targets, the use of solid-phase recombinase polymerase amplification strategy for DNA amplification with optical and electrochemical detection, the detection of real samples, the study of the surface chemistry and the combination of isothermal amplification with redox labelled dNTPs for the amplification and detection of toxic microalgae as an innovative method that permits incorporation of labels throughout the amplification process facilitating direct electrochemical detection of the DNA products and an inherent shortening of assay time.

This thesis deals with oportunity of ROC curve usage in the description of methods that work with sound signals. Specifically, it focuses on ways of detecting of stress in speech signals. The detection itselfs is done in a range of frequencies of the sound signal. There is also a classifier designed using ROC curves that decides whether the input signal is stressed or not. The output of this thesis are findings gathered from analyses and also some recommendation based on those analyses.

This research project aimed to develop a condition monitoring system for the final production quality of pharmaceutical tablets and detection capping and lamination during powder compression process using the acoustic emission (AE) method. Pharmaceutical tablet manufacturers obliged by regulatory bodies to test the tablet's physical properties such as hardness, dissolution and disintegration before the tablets are released to the market. Most of the existing methods and techniques for testing and monitoring these tablet's properties are performed at the tablet post-compression stage. Furthermore, these tests are destructive in nature. Early experimental investigations revealed that the AE energy that is generated during powder compression is directly proportional to the peak force that is required to crush the tablet, i. e. crushing strength. Further laboratory and industrial experimental investigation have been conducted to study the relationship between the AE signals and the compression conditions. Traditional AE signal features such as energy, count, peak amplitude, average signal level, event duration and rise time were recorded. AE data analysis with the aid of advanced classification algorithm, fuzzy C-mean clustering showed that the AE energy is a very useful parameter in tablet condition monitoring. It was found that the AE energy that is generated during powder compression is sensitive to the process and is directly proportional to the compression speed, particle size, homogeneity of mixture and the amount of material present. Also this AE signal is dependent upon the type of material used as the tablet filler. Acoustic emission has been shown to be a useful technique for characterising some of the complex physical changes which occur during tabletting. Capping and lamination are serious problems that are encountered during tabletting. A capped or laminated tablet is one which no longer retains its mechanical integrity and exhibit low strength characteristics. Capping and lamination can be caused by a number of factors such as excessive pressure, insufficient binder in the granules and poor material flowabilities. However, capping and lamination can also occur randomly and they are also dependent upon the material used in tabletting. It was possible to identify a capped or laminated tablet by monitoring the AE energy level during continuous on-line monitoring of tabletting. Capped tablets indicated by low level of AE energy. The proposed condition monitoring system aimed to set the AE energy threshold that could discriminate between capped and non-capped tablets. This was based upon statistical distributions of the AE energy values for both the capped and non-capped tablets. The system aims to minimise the rate of false alarms (indication of capping when in reality capping has not occurred) and the rate of missed detection (an indication of non capping, when in reality capping has occurred). A novel approach that employs both the AE method and the receiver operating characteristic (ROC) curve was proposed for the on-line detection of capping and lamination during tabletting. The proposed system employs AE energy as the discriminating parameter to detect between capped and non-capped tablets. The ROC curve was constructed from the area under the two distributions of both capped and non-capped tablet. This curve shows a trade-off between the probabilities of true detection rate and false alarm rate for capped and non-capped tablet. A two-graph receiver operating characteristic (ROC) curve was presented as a modification of the original ROC curve to enable an operator to directly select the desired energy threshold for tablet monitoring. This plot shows the ROC co-ordinate as a function of the threshold value over the entire threshold (AE energy) range for all test outcomes. An alternative way of deciding a threshold based on the slope of the ROC curve was also developed. The slope of the ROC curve represents the optimal operating point on the curve. It depends upon the penalties cost of capping and the prevalence of capping. Sets of guidelines have been outlined for decision making i.e. threshold setting. These guidelines take into account both the prevalence of capping in manufacturing and the cost associated with various outcomes of tablet formation. The proposed condition monitoring system also relates AE monitoring to non-AE measurement as it enable an operator predicting tablet hardness and disintegration form the AE energy, a relationship which was established in this research.

Dans une expérience classique de résonance paramagnétique électronique (RPE), le couplage entre les spins et leur environnement électromagnétique est faible, limitant considérablement la sensibilité de la mesure. Grâce à l’utilisation combinée d'un amplificateur paramétrique Josephson et de micro-résonateurs supraconductuers de hauts facteurs de qualité refroidis à quelques millikelvins, ce travail rapporte la conception et la mise en œuvre d’un spectromètre RPE dont la sensibilité de détection est limitée par les fluctuations quantiques du champ électromagnétique au lieu d’un bruit d’origine thermique ou technique. Des mesures de RPE pulsée sur un ensemble de doneurs Bismuth dans le silicium permettent de démontrer une sensibilité de 1700 spins détectés par écho de Hahn avec un signal-sur-bruit unitaire. La sensibilité est encore améliorée en générant un état de vide comprimé dans le guide d'onde de détection, ce qui réduit les fluctuations quantiques au-delà de la limite quantique. Les hauts facteurs de qualité et le petit volume de mode du résonateur supraconducteur développés pour une sensibilité accrue accroit également le couplage spin-résonateur jusqu'au point où les fluctuations quantiques ont un effet dramatique sur la dynamique des spins. En effet, l’émission spontanée de photons dans le résonateur micro-onde est considérablement renforcée par l'effet Purcell, ce qui en fait le mécanisme de relaxation de spin dominant. Le taux de relaxation est augmenté de trois ordres de grandeur lorsque les spins sont accordés à résonance, démontrant que la relaxation de spin peut-être contrôlée sur demande. Nos résultats fournissent une méthode nouvelle et universelle pour initialiser des systèmes de spin dans leur état fondamental, avec des applications en résonance magnétique et en information quantique
In usual electron-spin resonance (ESR) experiments, the coupling between spins and their electromagnetic environment is quite weak, severely limiting the sensitivity of the measurements. Using a Josephson parametric microwave amplifier combined with high-quality factor superconducting micro-resonators cooled at millikelvin temperatures, this work reports the design and implementation of an ESR setup where the detection sensitivity is limited by quantum fluctuations of the electromagnetic field instead of thermal or technical noise. Pulsed ESR measurements on an ensemble of Bismuth donors in Silicon spins demonstrate a sensitivity of 1700 spins within a single Hahn echo with unit signal-to-noise (SNR) ratio. The sensitivity of the setup is improved one step further by generating squeezed vacuum in the detection waveguide, reducing the amount of noise beyond the quantum limit. The high-quality factors and small mode volume superconducting microwave ESR resonator developed for enhanced sensitivity also enhances the spin-resonator coupling up to the point where quantum fluctuations have a dramatic effect on the spin dynamics. As a consequence, the spin spontaneous emission of microwave photons in the resonator is dramatically enhanced by the Purcell effect, making it the dominant spin relaxation mechanism. The relaxation rate is increased by three orders of magnitude when the spins are tuned to resonance, showing that spin relaxation can be engineered and controlled on-demand. Our results provide a novel and general way to initialize spin systems into their ground state, with applications in magnetic resonance and quantum information processing

In this thesis, an investigation was performed to find ways of differencing between firesand vehicles at waste stations in hope of removing vehicles as a source of error duringearly fire detection. The existing system makes use of a heat camera, which rotates in 48different angles (also known as zones) in a fixed position. If the heat is above a certainvalue within a zone the system sounds the fire alarm.The rotation of the camera results in an unwanted displacement between two successiveframes within the same zone. By use of image registration, this displacement wasremoved. After the registration of an image, segmentation was performed where coldobjects are eliminated as an error source. Lastly, an analysis was performed upon thewarm objects.At the end, it was proven that the image registration had been a successful improvementof the existing system. It was also shown that vehicles can, to some extent, beeliminated as an error source.
I denna uppsats görs en undersökning av sätt att urskilja mellan bränder och fordon vid avfallsbunkrar, i hopp om att ta bortfordon som felkälla under tidig branddetektion. Dagens system använder sig av en värmekamera som roterar i 48 vinklar(även kallade zoner) från en fix position och larmar då det blir för varmt i någon zon.Roteringen av kameran medför en icke önskvärd förskjutning mellan två efterföljande bilder inom samma zon. Processenbildregistrering används för att eliminera denna förskjutning. Efter registreringen utförs en segmentering där kalla objekt tasbort som felkälla. När detta är utfört görs en analys av de varma objekten med en mängd mätningar.I slutet bevisas att registreringen har fungerat mycket väl, likaså att det går till viss del att eliminera fordon som felkällaunder tidig brandetektion.

In wildlife management, using cutting edge technology and science to monitor greater sage-grouse (Centrocercus urophasianus; sage-grouse) populations, enables land managers to better assess the impact of their management decisions. Having precise counts of sage-grouse lek attendance, and specifically male lek attendance, is an important metric used to evaluate population status and response to conservation actions (Gifford et.al, 2013, Dahlgren et al., 2016). Leks are seasonal breeding sites where males perform a ritualistic courtship dance for females. Our case study examined if a Remotely Piloted Aircraft (RPA) was effective in detecting, and counting, sage-grouse during the lek season (early March to late April). More specifically, this research used a Forward-Looking Infrared (FLIR) camera (a thermal camera) to detect sage-grouse and determine body temperatures of individual sage-grouse to determine if temperature data can be used to identify displaying male sage-grouse. These images can be used to document the activity and behavior of sage-grouse and can be revisited at future times to document changes in bird numbers as well as perform additional statistical analyses. We conducted 5 flights and on a per-flight basis, we identified an average of 4.4 displaying males, 13.4 non-displaying males, and 5.6 female sage-grouse. We found that the average size and average maximum temperature of the three sage-grouse categories differed where females were smaller with an average body size of 325 cm2, an average maximum temperature of 14.6 C ̊, and a smaller average thermal range of 2.47 C ̊. Non-displaying male body size was approximately 488 cm2, with a maximum average temperature of 17.2 C ̊, and an average thermal range of 4.66C ̊. Displaying male body size was the largest at approximately 655 cm2, an average maximum temperature of 27.5C ̊, with the largest average range of 12.39C ̊. Our study demonstrates that RPA and infrared technology can be used to conduct accurate sage-grouse lek attendance counts. Further, results of this study will also provide a guideline for the use of RPA’s to monitor sage-grouse and other lekking species.

L'echauffement de l'echantillon du a la resonance est detecte, soit avec un thermometre au carbone, soit avec un microphone. Aux temperatures de l'helium liquide, ces methodes sont sensibles aux ions john teller fortement couples au reseau et donnent des signaux qui ne peuvent etre obtenus par rpe classique. Des systemes de raies intenses mis en evidence dans les deux composes sont crees et amplifies par l'illumination. Les centres responsables sont des centres v**(2+) associes dont l'etat le plus bas est constitue d'au moins trois doublets de kramers

The present thesis work has been carried out in the framework of the CMS collaboration, one of the experiment designed to study the physics of the proton-proton collisions at the Large Hadron Collider (LHC) at CERN. Experimentation at CMS (and at ATLAS) led to the discovery of a new particle in 2012 which has been identified as the Higgs boson, the missing brick of the Standard Model of the fundamental interactions. All the experiments at LHC are upgrading their detectors in order to fulfill the continuous increment of the LHC luminosity and the consequent increment of the per collision event rate. The CMS upgrade project foresees, inter alia, the production of a new pixel detector (CMS Phase 1 Pixel Upgrade) to be commissioned at the beginning of 2017. Crucial part of the upgrade is the new readout chip (ROC) for the silicon sensor, psi46digV2respin, designed at the Paul Scherrer Institute (PSI) with a 250 nm CMOS technology. This chip represents the state of the art in the readout electronics for the silicon detectors. The thesis concerns the study and the development of test procedures for this new readout chip. Thanks to a long stay at PSI, I could provide an important contribution to the debug phases of the first version of the ROC and TBM, the chip that handles the various ROCs in the pixel module, and to the development of the software used by the whole collaboration for the ROC and module testing. This experience allowed me to be the expert for the installation and commissioning of the ROC readout system in all the production centres in Italy. Furthermore, I managed the ROC wafers test from the early project phases. The ROCs are produced on silicon wafers and undergo various processes before being assembled on the modules, e.g., metal deposition on the pixel pads, thinning and dicing. These processes lead mechanical and thermal stresses that can damage the chips. The ROC wafers test has thus been performed following the same procedure before and after the processing. In order to minimize the failing ROCs fraction mounted on the modules. It has been measured that the processing introduces a 5.2 % reduction of the number of perfectly working ROCs. The pixel detector production line, the module qualification process and the ROC wafers test results are reported in this thesis. The modifications performed on the ROC-sensor connection technology are also described. The new pixel detector installation will allow an increase of the tracks reconstruction efficiency and a 10-15 um resolution to be maintained in the interaction vertices reconstruction, independently from the increment of the mean number of events per p-p interaction from the current 15 to 50-60 in 2017. The excellent performances of the new pixel vertex detector plus the planned increment of the luminosity (a factor 35 between 2017 and the current value) could allow access to physical processes with a low cross section and a high number of b quarks in the final states. For this purpose, a preliminary study on the non-resonant Higgs bosons pair production in the fully hadronic decay channel bbbb is here presented. The study has been performed analysing the data collected by the CMS experiment in 2015, equal to 2.19 fb-1. This process has a low cross section, accordingly to the SM, and its measurement in p-p collision at centre of mass energies of 13-14 TeV is forecast only with a high amount of data (ab-1). The data collected in 2015 do not allow to set a reasonable exclusion limit on the cross section of this process and the analysis will be completely developed in 2016 and following years. The study of the Higgs bosons pair production is relevant because the pairs can be produced also after couplings which are not allowed by the Standard Model (anomalous), such as the higgs-gloun contact interaction. These anomalous couplings lead to an increment of the cross section of the process and to differences in the kinematics of the final states. The process of Higgs bosons pair production via anomalous couplings is described by a Lagrangian with five free parameters. This implies a difficulty in the identification of parameters space point to be experimentally investigated. I developed an analysis technique which allows, by studying simulated samples, to divide the parameters space in kinematically similar regions and to identify a benchmark in each of them. The distance among different points of the parameters space has been defined through a binned likelihood ratio and an iterative algorithm has been developed to group them together. Twelve regions which are kinematically equivalent have been identified in a 5-D space. The results of this study, described in this thesis, are collected in an article which is under publication on JHEP and they will be considered as guideline for the searches of non-resonant Higgs bosons pair production at CMS.
Questo lavoro di tesi è stato svolto nell'ambito della collaborazione CMS, uno degli esperimenti progettati per studiare la fisica delle collisioni protone-protone al Large Hadron Collider (LHC) presso il CERN. La sperimentazione a CMS (ed a ATLAS) ha portato nel 2012 alla scoperta di una nuova particella che è stata in seguito identificata come il bosone di Higgs, l'ultimo tassello mancante dello Standard Model delle interazioni fondamentali. Tutti gli esperimenti a LHC sono in una fase di miglioramento degli apparati in vista del continuo aumento di luminosità di LHC e del conseguente aumento del rate di eventi per collisione. Il progetto di upgrade di CMS prevede tra l'altro la produzione di un nuovo rivelatore a pixel (CMS Phase 1 Pixel Upgrade) da inserire nell'apparato all'inizio del 2017. Parte cruciale dell'upgrade è il nuovo chip di lettura (ROC) dei sensori al silicio, psi46digV2respin, disegnato al Paul Scherrer Institute (PSI) in tecnologia CMOS 250 nm. Tale chip rappresenta lo stato dell'arte nell'elettronica di lettura di rivelatori al silicio. La tesi riguarda lo studio e lo sviluppo di procedure di test di questo nuovo chip di lettura. Grazie ad una lunga permanenza al PSI ho potuto fornire un importante contributo alle fasi di debug delle prime versioni del ROC e del TBM, il chip che gestisce i diversi ROCs all'interno di un pixel module, ed allo sviluppo del software utilizzato da tutta la collaborazione per il test del ROC e dei moduli. Questa esperienza mi ha permesso essere l'esperto per l'installazione e messa a punto dei sistemi di lettura dei ROC nei centri di produzione di moduli in Italia. Inoltre ho gestito il test dei ROC wafers fin dalle prime fasi di sviluppo del progetto. I ROC sono prodotti su wafers di silicio e subiscono diversi processi di lavorazione prima dell'assemblaggio sui moduli, e.g., la deposizione di metalli sulle pixel pads, l'assottigliamento ed il taglio. Queste lavorazioni comportano stress meccanici e termici che possono danneggiare i chips. Il test dei ROC wafers è stato quindi effettuato, con la stessa procedura, prima e dopo la lavorazione per ridurre al minimo la frazione di ROCs non funzionanti montati sui moduli. Si è misurato che la lavorazione dei wafers introduce una riduzione del 5.2 % del numero di ROCs perfettamente funzionanti. Nella tesi sono riportati la catena di produzione del rivelatore a pixel, il processo di qualifica dei moduli ed il dettaglio dei test su ROC wafers. Vengono inoltre descritte le modifiche apportate alla tecnologia utilizzata per la connessione ROC-sensore. L'installazione del nuovo rivelatore a pixel permetterà di aumentare l'efficienza di ricostruzione delle tracce e di mantenere una risoluzione di 10-15 um nella ricostruzione dei vertici d'interazione anche all'aumentare del numero medio di eventi per interazione p-p dagli attuali 15 a 50-60 nel 2017. Le ottime prestazioni del nuovo rivelatore di vertice a pixel sommate al previsto aumento di luminosità (un fattore 35 tra il valore attuale e quello previsto per il 2017) potranno dare accesso a processi fisici con bassa sezione d'urto ed alto numero di b quarks negli stati finali. Viene a tal fine presentato uno studio preliminare della produzione non risonante di coppie di bosoni di Higgs nel canale di decadimento completamente adronico (bbbb) analizzando i dati raccolti dall'esperimento CMS nel 2015, pari a 2.19 fb-1. Questo processo presenta una ridotta sezione d'urto, secondo il Modello Standard, e la sua misura in collisioni p-p ad energie del centro di massa di 13-14 TeV è prevista solo con un'elevata quantità di dati (ab-1). I dati raccolti nel 2015 non permettono di ottenere un limite ragionevole sulla sezione d'urto di produzione di tale processo e l'analisi verrà sviluppata pienamente nel 2016 e nei successivi anni. Lo studio della produzione di coppie di bosoni di Higgs è rilevante poiché esse possono essere prodotte anche in seguito ad accoppiamenti non previsti dal Modello Standard (anomali), come l'interazione di contatto tra bosoni di Higgs e gluoni. Tali accoppiamenti anomali danno luogo ad un incremento della sezione d'urto del processo e ad una differente cinematica degli stati finali. Il processo di produzione di coppie di bosoni di Higgs per mezzo di accoppiamenti anomali è descritto da una Lagrangiana con cinque parametri liberi. Questo comporta una difficoltà nell'individuare i punti dello spazio dei parametri da indagare sperimentalmente. Ho sviluppato una tecnica di analisi che permette, attraverso lo studio di campioni simulati, di suddividere tale spazio in regioni cinematicamente simili ed identificare per ognuna di esse il punto maggiormente significativo. La distanza tra i diversi punti dello spazio dei parametri è stata definita tramite un ”binned likelihood ratio” ed un algoritmo iterativo è stato sviluppato per raggruppare tali punti. Sono state quindi individuate dodici regioni cinematicamente simili in uno spazio 5-D. I risultati di tale studio, descritti in questa tesi, sono raccolti in un articolo in fase di pubblicazione su JHEP e verranno considerati come linee guida per le ricerche di produzione non risonante di coppie di bosoni di Higgs a CMS.

Aim of this thesis is description of neural network based edge detection methods that are substitute for classic methods of detection using edge operators. First chapters generally discussed the issues of image processing, edge detection and neural networks. The objective of the main part is to show process of generating synthetic images, extracting training datasets and discussing variants of suitable topologies of neural networks for purpose of edge detection. The last part of the thesis is dedicated to evaluating and measuring accuracy values of neural network.

The growing need for fast sampling of explosives in high throughput areas has increased the demand for improved technology for the trace detection of illicit compounds. Detection of the volatiles associated with the presence of the illicit compounds offer a different approach for sensitive trace detection of these compounds without increasing the false positive alarm rate. This study evaluated the performance of non-contact sampling and detection systems using statistical analysis through the construction of Receiver Operating Characteristic (ROC) curves in real-world scenarios for the detection of volatiles in the headspace of smokeless powder, used as the model system for generalizing explosives detection. A novel sorbent coated disk coined planar solid phase microextraction (PSPME) was previously used for rapid, non-contact sampling of the headspace containers. The limits of detection for the PSPME coupled to IMS detection was determined to be 0.5-24 ng for vapor sampling of volatile chemical compounds associated with illicit compounds and demonstrated an extraction efficiency of three times greater than other commercially available substrates, retaining >50% of the analyte after 30 minutes sampling of an analyte spike in comparison to a non-detect for the unmodified filters. Both static and dynamic PSPME sampling was used coupled with two ion mobility spectrometer (IMS) detection systems in which 10-500 mg quantities of smokeless powders were detected within 5-10 minutes of static sampling and 1 minute of dynamic sampling time in 1-45 L closed systems, resulting in faster sampling and analysis times in comparison to conventional solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis. Similar real-world scenarios were sampled in low and high clutter environments with zero false positive rates. Excellent PSPME-IMS detection of the volatile analytes were visualized from the ROC curves, resulting with areas under the curves (AUC) of 0.85-1.0 and 0.81-1.0 for portable and bench-top IMS systems, respectively. Construction of ROC curves were also developed for SPME-GC-MS resulting with AUC of 0.95-1.0, comparable with PSPME-IMS detection. The PSPME-IMS technique provides less false positive results for non-contact vapor sampling, cutting the cost and providing an effective sampling and detection needed in high-throughput scenarios, resulting in similar performance in comparison to well-established techniques with the added advantage of fast detection in the field.

This document deals with experimental verifying to use machine learning algorithms AdaBoost or WaldBoost to make classifier, that is able to find point in the second picture that matches original point in the first picture. This work also depicts finding points of interest in image as a first step of finding correspondence. Next there are described some descriptors of points of interest. Corresponding points could be useful for 3D modeling of shooted scene.

Atrial fibrillation is a common heart arrhythmia which is characterized by a missing or irregular contraction of the atria. The disease is a risk factor for other more serious diseases and the total medical costs in society are extensive. Therefore it would be beneficial to improve and optimize the prevention and detection of the disease.   Pulse palpation and heart auscultation can facilitate the detection of atrial fibrillation clinically, but the diagnosis is generally confirmed by an ECG examination. Today there are several algorithms that detect atrial fibrillation by analysing an ECG. A common method is to study the heart rate variability (HRV) and by different types of statistical calculations find episodes of atrial fibrillation which deviates from normal sinus rhythm.   Two algorithms for detection of atrial fibrillation have been evaluated in Matlab. One is based on the coefficient of variation and the other uses a logistic regression model. Training and testing of the algorithms were done with data from the Physionet MIT database. Several steps of signal processing were used to remove different types of noise and artefacts before the data could be used.   When testing the algorithms, the CV algorithm performed with a sensitivity of 91,38%, a specificity of 93,93% and accuracy of 92,92%, and the results of the logistic regression algorithm was a sensitivity of 97,23%, specificity of 93,79% and accuracy of 95,39%. The logistic regression algorithm performed better and was chosen for implementation in Java, where it achieved a sensitivity of 97,31%, specificity of 93,47% and accuracy of 95,25%.
Förmaksflimmer är en vanlig hjärtrytmrubbning som kännetecknas av en avsaknad eller oregelbunden kontraktion av förmaken. Sjukdomen är en riskfaktor för andra allvarligare sjukdomar och de totala kostnaderna för samhället är betydande. Det skulle därför vara fördelaktigt att effektivisera och förbättra prevention samt diagnostisering av förmaksflimmer.   Kliniskt diagnostiseras förmaksflimmer med hjälp av till exempel pulspalpation och auskultation av hjärtat, men diagnosen brukar fastställas med en EKG-undersökning. Det finns idag flertalet algoritmer för att detektera arytmin genom att analysera ett EKG. En av de vanligaste metoderna är att undersöka variabiliteten av hjärtrytmen (HRV) och utföra olika sorters statistiska beräkningar som kan upptäcka episoder av förmaksflimmer som avviker från en normal sinusrytm.   I detta projekt har två metoder för att detektera förmaksflimmer utvärderats i Matlab, en baseras på beräkningar av variationskoefficienten och den andra använder sig av logistisk regression. EKG som kommer från databasen Physionet MIT används för att träna och testa modeller av algoritmerna. Innan EKG-signalen kan användas måste den behandlas för att ta bort olika typer av brus och artefakter.   Vid test av algoritmen med variationskoefficienten blev resultatet en sensitivitet på 91,38%, en specificitet på 93,93% och en noggrannhet på 92,92%. För logistisk regression blev sensitiviteten 97,23%, specificiteten 93,79% och noggrannheten 95,39%. Algoritmen med logistisk regression presterade bättre och valdes därför för att implementeras i Java, där uppnåddes en sensitivitet på 91,31%, en specificitet på 93,47% och en noggrannhet på 95,25%.

Foreign objects in Chest X-ray (CXR) cause complications during automatic image processing. To prevent errors caused by these foreign objects, it is necessary to automatically find them and ommit them in the analysis. These are mainly buttons, jewellery, implants, wires and tubes. At the same time, finding pacemakers and other placed devices can help with automatic processing. The aim of this work was to design a method for the detection of foreign objects in CXR. For this task, Faster R-CNN method with a pre-trained ResNet50 network for feature extraction was chosen which was trained on 4 000 images and lately tested on 1 000 images from a publicly available database. After finding the optimal learning parameters, it was managed to train the network, which achieves 75% precision, 77% recall and 76% F1 score. However, a certain part of the error is formed by non-uniform annotations of objects in the data because not all annotated foreign objects are located in the lung area, as stated in the description.

This diploma thesis deals with detection of atrial fibrillation from HRV, classification of Poincare map and in the end the divide into two groups, one with detected atrial fibrillation and one not. The result is the decision on which variables are statistically significant for the identification of atrial fibrillations and which are not, and classification of the ECG signals.

This thesis consists of the evaluation of sensor-based risk management against oil spills using an underwater distributed sensor network. The work starts by highlighting the importance of having a performing leak detection system both from an environmental, safety and economic point of view. The case study is the Goliat FPSO in the Barents Sea which has to meet requirements dictated by Norwegian authorities to prevent oil spills. The modeled network is made of passive acoustic sensors monitoring the subsea manifolds. These sensors send their local 1-bit decision to a Fusion Center which takes a global decision on whether the leakage is occurring. This work evaluates how the choice of adapted Fusion Rules (Counting Rule and Weighted Fusion Rule) can affect the performances of the leak detection system in its current geometry. It will also be discussed how different thresholds, selected for a specific FR or sensor test, can change the system performance. The detection methods are based on statistical signal processing adapted to fit this application within the Oil&Gas field. The work also proposes some new leak localization methods developed so they can be coupled with the proposed leak detection methods, giving a coherent set of operations that the sensors and the FC must perform. Performances of detection techniques are assessed balancing the need for high values of True Positive Rate and Precision and low values of False Positive Rate using indexes based both on the ROC curve (like the Youden's Index) and on the PR curve (the F-scores). Whereas, performances of localization techniques will be assessed on their ability to localize the spill in the shortest time; if this is not possible, parameters like the difference between the estimated and the real leak position will be considered. Finally, some tests are carried out applying the different sets of proposed methods.

The use of autonomous robots in our society is increasing every day and a robot is no longer seen as a tool but as a team member. The robots are now working side by side with us and provide assistance during dangerous operations where humans otherwise are at risk. This development has in turn increased the need of robots with more human-awareness. Therefore, this master thesis aims at contributing to the enhancement of human-aware robotics. Specifically, we are investigating the possibilities of equipping autonomous robots with the capability of assessing and detecting activities in human teams. This capability could, for instance, be used in the robot's reasoning and planning components to create better plans that ultimately would result in improved human-robot teamwork performance. we propose to improve existing teamwork activity recognizers by adding intangible features, such as stress, motivation and focus, originating from human behavior models. Hidden markov models have earlier been proven very efficient for activity recognition and have therefore been utilized in this work as a method for classification of behaviors. In order for a robot to provide effective assistance to a human team it must not only consider spatio-temporal parameters for team members but also the psychological.To assess psychological parameters this master thesis suggests to use the body signals of team members. Body signals such as heart rate and skin conductance. Combined with the body signals we investigate the possibility of using System Dynamics models to interpret the current psychological states of the human team members, thus enhancing the human-awareness of a robot.
Användningen av autonoma robotar i vårt samhälle ökar varje dag och en robot ses inte längre som ett verktyg utan som en gruppmedlem. Robotarna arbetar nu sida vid sida med oss och ger oss stöd under farliga arbeten där människor annars är utsatta för risker. Denna utveckling har i sin tur ökat behovet av robotar med mer människo-medvetenhet. Därför är målet med detta examensarbete att bidra till en stärkt människo-medvetenhet hos robotar. Specifikt undersöker vi möjligheterna att utrusta autonoma robotar med förmågan att bedöma och upptäcka olika beteenden hos mänskliga lag. Denna förmåga skulle till exempel kunna användas i robotens resonemang och planering för att ta beslut och i sin tur förbättra samarbetet mellan människa och robot. Vi föreslår att förbättra befintliga aktivitetsidentifierare genom att tillföra förmågan att tolka immateriella beteenden hos människan, såsom stress, motivation och fokus. Att kunna urskilja lagaktiviteter inom ett mänskligt lag är grundläggande för en robot som ska vara till stöd för laget. Dolda markovmodeller har tidigare visat sig vara mycket effektiva för just aktivitetsidentifiering och har därför använts i detta arbete. För att en robot ska kunna ha möjlighet att ge ett effektivt stöd till ett mänskligtlag måste den inte bara ta hänsyn till rumsliga parametrar hos lagmedlemmarna utan även de psykologiska. För att tyda psykologiska parametrar hos människor förespråkar denna masteravhandling utnyttjandet av mänskliga kroppssignaler. Signaler så som hjärtfrekvens och hudkonduktans. Kombinerat med kroppenssignalerar påvisar vi möjligheten att använda systemdynamiksmodeller för att tolka immateriella beteenden, vilket i sin tur kan stärka människo-medvetenheten hos en robot.

The thesis work was conducted in Stockholm, Kista at the department of Informatics and Aero System at Swedish Defence Research Agency.

Materials play an important role in the elementary particle detectors technology. The detector is one of the basic instrument in experimental particle physics research. The detector material choice is based on detection requirements, i.e., precision, efficiency, dimensions and cost. Many types of detectors are being used to identify and study elementary particles in diverse fields, such as medical, homeland security, cosmology, nuclear, subnuclear, astro and particle physics. The studies presented in this thesis concern materials that are used (or planned to be used) in two types of particle detection technologies such as Resistive Plate Counters (RPC) and the Gas Electron Multiplier (GEM) detectors for muon particles detection at the Compact Muon Solenoid (CMS) experiment. CMS records and identifies collisions between protons accelerated at the highest energies ever reached by the Large Hadron Collider (LHC), located at the European Centre for Nuclear Research (CERN) in Geneva, Switzerland. CMS is one of the four main particle detectors at the LHC. Goal of CMS and the LHC is to produce, detect and study the Higgs boson, and the elusive new particles that could explain the dark matter enigma in the Universe. The Higgs boson was observed in 2012, and since then new statistically significant data was accumulated. The new particles are being searched for in the data taking period just started (March 2017) that will continue for more than 10 years at ever increasing intensity and energy. CMS is composed of many sub-detectors systems such as silicon tracker, electromagnetic & hadronic calorimeter, muon systems, all immersed in the most powerful magnetic field ever built for momentum measurement. The muon system is of paramount importance, because of the prevalence of the new particles to decay in final states with a large content of muon particles. The CMS muon system uses three particle detection technologies, such as Drift Tubes (DTs) detectors, Cathode Strips Chambers (CSCs) and Resistive Plate Chambers (RPCs). The DTs and CSCs provide a precise measurement points for muon triggering and identification; the DTs and CSCs are installed in barrel and endcap region respectively and give coverage up to 0 < ||< 2.4, with being the pseudo-rapidity. The RPCs detectors provide an extra muon trigger, these are installed in both barrel and endcap regions. The existing RPC system has a coverage up to || < 1.6. Beyond this region the eight endcap stations are empty. To cover the high region, novel detectors are required in order to cope with high radiation level resulting by high density of particles. The Gas Electron Multiplier (GEM) technology was proposed and approved. This thesis reports on material studies carried on to characterize both the RPC and the GEM detectors. In the first phase of upcoming data taking periods (so called long shutdown 2 or LS2, scheduled for 2019), a GEM chamber station called GE1/1 will be installed. In the second phase called High-Luminosity LHC and scheduled in LS3 (2024), additional subsystems with GEM and RPC technology have been proposed as candidates for additional stations. The study of the main material composing a GE1/1 detector (the GEM foil) is the first part of the thesis. The GEM foil is the basic component of the detector, and it plays a vital role for detection of the particles. The foil is composed of 50 μm thick polyimide film, coated with 5 μm copper on both sides, it is perforated with the micro size holes such as outer diameter of the hole is 70 μm, inner diameter 50 μm and pitch (distance between two consecutive holes) is 140 μm. In one detector a stack of three GEM foils is used, the area of the foil is about 0.345 m2 (short GE1/1 detector), 0.409 m2 (long GE1/1 detector). By design the spacing among the foils in the stack will be 1-3 mm. To assemble the detector the foils stack is stretched with a specially designed pull-out arranged around the detector, which uses 58 lateral screws (for short GE1/1 detector). During stretching, if the applied force is beyond the elastic limit or force applied non-uniformly across the screws, then the micro holes could have deformed. The electric field lines produced during detector operation, will be also deformed/dispersed accordingly, and this will directly affect the detector performance. The detectors have to perform for about 20 years at CMS in high radiations environment, therefore it is important to study the radiation impacts on the tensile properties of the foil. The long-term stability test is also of paramount importance. The GE1/1 foil is an asymmetric mechanically (due to the formation of the HV sectors with non-uniform spacing), so the asymmetry studies are important to know that in which orientation the foil can deform differently by applying uniform stress. The studies on GEM materials are performed by using both conventional and non-conventional techniques. In conventional techniques, we used stretching machine for tensile characterization and same setup was used for the creep test by adjusting the stress accordingly. For GEM foil holes deformation study a high resolution microscope was used along with the tensile test setup as mentioned above. In the non-conventional technique we used Moir´e interferometry to measure the flatness of the top foil of the stack, this optical method was used to characterize GE1/1 foils in situ, i.e., inside the GE1/1 assembled full size chambers under varying stress along the lateral screws. This test is helpful to optimize and to attain maximum possible flatness of the foil under nominal stress. Furthermore, Moir´e interferometry does not require physical contact with foil during the measurement, due to this reason this method is safer with respect to damaging the foil. This method allows to verify that about 80 μm precision can be reached on the transverse plane, well suited to the operation specifications of the GE1/1 foils. In the second non-conventional method, we used Fiber Bragg´s Grating (FBG) sensors to measure the strain at various points on the three GEM foils stack simultaneously during tightening the GEM foils stack. The demonstration of installing and measuring of the strain variation from the FBGs sensors on the GE1/1 three foils simultaneously also leads to the idea to install the FBG sensors on some of the final version of the GE1/1 chambers and to monitor the affects of high magnetic field at the GEM foil during operation at the CMS. For tensile characterization we not only used the GEM foil but also the kapton (non-copper coated and non-perforated) which is the base material of the GEM foil. The purpose of GEM material characterization is to see the tensile trends by applying continuously increasing stress and the estimation of the elastic limit, and the aging affects due to radiation such as gamma and neutron. The different environmental conditions could affect the tensile trends and elastic limit therefore the samples are conditioned not only in radiation but also in different temperature and humidity environment. In addition to all these conditioning, one set of the vii sample is treated in the harsh environment such as kept in the oven at 360o C. These various types of conditioning help to understand deeply the mechanical properties of the GEM material. The tensile tests provided the Young’s modulus of GEM and kapton foils. It was observed the degradation due to neutron irradiation in the elastic region for both kapton and GEM foil. Neither moisture nor dryness affect significantly the tensile properties. However, the heat treatment drastically degraded the material in the elastic regime and beyond. The long term stability test of the GE1/1 foil under constant stress (creep test) was performed. For this test, samples are taken from unused GE1/1 foil, two tests were performed separately in both longitudinal and transverse directions. The reason to perform the two tests is the asymmetry in the GE1/1 foil. The asymmetry arises in the foil due to HV sectors formation, and each sector is separated by about 1-2 mm wide lines without copper coating and the holes. Creep test provide the characterization of GE1/1 foils for long term stability under constant load. The second part of this thesis is focussed on developing and characterizing the RPC detector new material. The RPCs are already in operation in many experiments particularly at the LHC experiments such as CMS and ATLAS. In future the RPC are being considered in the upgrade project of the muon system particularly for the CMS. The CMS upgrade plan is linked with the LHC upgrade in which the luminosity will be enhanced, this enhanced luminosity era of the LHC is called the HL-LHC. During HL-LHC high rate of particles is expected and therefore faster detectors are required, which should have better capability of sustaining in very high particle rates without suffering from electrical discharges and aging. To make the RPCs faster a lot of R & D programs are on going. Along with other things such as fast front end electronics and detector design (reducing the gap size), the most important thing is the electrodes material. A good quality internal surface of the gaps (electrodes) and moderate resistivity could improve the RPCs performance. The efforts to modify the existing material and to develop a new material will be not only useful to meet the HL-LHC challenges particularly, but also good for the RPC detector technology in general. Therefore the focus of my work in last part of thesis is to modify the existing material and to develop the new material and its characterization. The existing and the standard RPC electrodes are made with two Bakelite electrodes which have resistivity of 1010 − 1012W.cm, the electrodes are coated internally with linseed oil and externally with graphite. The linseed oil is used to make the surface smooth and graphite coating is necessary to enhance external surface conductivity which help to distribute high potential (10 kV) uniformly across the electrodes to generate a uniform electric field along the entire gas gap. The particle detection rate capability depends on the electrodes material surface quality and its resistivity. For the RPCs material study a two-fold approach was adopted such as: modification of the existing material, and development of a new material for the electrodes. In the first approach, we replaced the linseed oil with polyimide and, to control resistivity, we added carbon black and graphene in the polyimide. To coat the electrodes (bakelite sheet) with polyimide and polyimide mixed additives different techniques are adopted such as spray, spin coating etc.., after the coating treated viii the samples surface in control temperature and humidity environment to make it dry and sticky with the base material. The inspection of surface morphology and roughness SEM and AFM respectively were used. The chemical structure of the surface was studied via FTIR analysis. For resistivity measurement arranged a setup in which the surface and bulk resistivity was measured separately. For moisture absorption rate measurements a dedicated setup was built. In the second approach of the strategy we developed a new material for the RPCs electrodes. It consists of polyimide and additives. To make the self sustained samples we used the thick the solutions of polyimide and uniformly mixed the additives (carbon black and graphene pellets). Samples were dried adopting two different procedures: room temperature and oven desiccation. After that FTIR, AFM, SEM, resistivity and moisture absorption tests were performed. The detail procedure and results are reported in the chapter 7, the results are very encouraging. Future plan includes to keep continue this research by building a prototype by using the new material and to study and validate the material by looking the performance of the detector.

Este trabalho pretende dar a conhecer o desempenho e a viabilidade de uma nova electrónica de leitura, integralmente concebida para futura aplicação a um sistema de detectores gasosos do tipo tRPC (timing Resistive Plate Chamber) destinado a tomografia por emissão de positrões com tempo de voo (Time-Of-Flight - Positron Emission Tomography TOF- -PET). Depois de se ter acesso ao desenho (em versão esquemática) da electrónica de leitura estudou-se os resultados obtidos através da simulação para posterior concepção da placa de circuito impresso (Printed Circuit Board - PCB). Duas versões foram concebidas, sendo a segunda uma optimização da primeira. A última versão apresentou resultados muito favoráveis passando-se de seguida ao estudo experimental com os detectores tRPC. Os dados obtidos foram analisados e melhorados através de um algoritmo que efectuou as correcções necessárias. Obteve-se uma resolução temporal de 90ps σ, ou seja, 300ps FWHM para o sistema detector tRPC e electrónica de leitura.

INO is an Indian-based Neutrino Observatory project which is a multi-Institutional Collaboration for setting up a magnetized Iron Calorimeter (ICAL) detector to detect atmospheric neutrino and study their properties. It is a world class underground laboratory for high energy experimental and nuclear physics research in India. The primary goal of INO is to study Neutrino because they are the fundamental particles having little mass but were expected to be massless in standard of particle physics. Today, determination of neutrino masses and mixing parameters is one the most challenging open problem in physics. So, ICAL detector is going to be designed to address this key open problem in a unique way. The Resistive Plate Chamber (RPC) detectors (with a single gas gap) have been chosen as the active detector elements for the magnetized iron calorimeter (ICAL) detector at INO, due to their excellent efficiency, position (mm) & timing (ns) characteristics and suitability for large detector coverage. I have done the fabrication and preliminary characterization including efficiency, counting rate, leakage current and time resolution of RPC detectors (dimension 30 cm × 30 cm). I took two glasses of 2 mm thickness coated with a conductive layer of graphite, are used as the external electrodes. The pickup panel consists of honeycomb panels with copper strips of width 2 cm. The gas gaps are sealed by gluing side spacers between the outermost electrodes. The RPCs are being tested in avalanche mode with a gas mixture of Freon (R134a-95.15%), Isobutane ( -4.51%), (0.34%) with a flow rate of 5 SCCM. Three scintillator paddles of width 2 cm in coincidence mode has been used for the trigger. The signals from the pickup strips are amplified with the NINO ASIC chip and then taken with coincidence with the trigger. An ultra-fast front-end preamplifier-discriminator chip NINO has been developed for use in the ALICE Time-Of-Flight detector. The chip has 8 channels and each channel is designed with an amplifier with less than 1 ns peaking time, a discriminator with a minimum detection threshold of 10fC and an output stage. The output pulse has minimum time jitter (less than 25ps) on the front edge, and the pulse width is dependent of the input signal charge. Each channel in NINO chip takes the differential signal from the pickup strips as input, and amplifies them in a four stage cascade amplifier. The study on the detector performance with varying HV and at different concentrations of the gas mixture components will be presented in detail.

Important developments have occurred newly in neutrino physics and neutrino astronomy. Oscillations of neutrinos, and the inferred evidence that neutrinos have mass, are likely to have far-reaching consequences. This discovery has come from the study of neutrinos from the Sun and those produced in interactions of cosmic rays with the earth’s atmosphere. The groundbreaking Home stake Mine Neutrino Experiment in the USA, the gigantic Super-Kamiokande detector and the KamLAND detector in Japan, the Heavy-water detector at the Sudbury Neutrino Observatory in Canada, and a few other laboratories, together, have contributed in a very basic way to our information of neutrino properties and interactions. Encouraged by these discoveries and their implications for the future of particle physics, plans have been made world-wide, for new neutrino detectors, neutrino factories and long base-line neutrino experiments. Indian scientists started initiating in atmospheric neutrino experiments. In fact, neutrinos produced by cosmic ray interactions in the earth’s atmosphere were first detected in the deep mines of the Kolar Gold Fields (KGF) in south India in 1965. In order to revive underground neutrino experiments in India, a multi-institutional collaboration has been formed with the objective of creating an India-based Neutrino Observatory (INO). Considering the physics possibilities and given the past experience at KGF, the INO collaboration has decided to build a magnetised Iron CALorimeter (ICAL) detector with Resistive Plate Chambers (RPCs) as the active detector elements. In the first phase of its operation, ICAL will be used for atmospheric neutrino physics with the aim of making precision measurements of the parameters related to neutrino oscillations. The detector will be magnetised to a field of about 1.3 T, enabling it to distinguish the positive and negative muons and thus identifying muon-type neutrino and anti-neutrino produced events separately. This will be useful for ICAL to provide an exciting possibility to determine the ordering of the neutrino mass levels. Finally, this detector can also be used as the far-detector of a futuristic long-base-line neutrino experiment ix using the neutrino beam from a neutrino factory. Good tracking, energy and time resolutions as well as charge identification of the detecting particles are the essential capabilities of this detector. The ICAL experiment will need about 27,600 RPCs each of about 200 cm × 200 cm in area. RPCs are fast, planar, rugged and low-cost gas detectors which are being, and will be, used extensively in a number of high energy and astro-particle physics experiments. They find applications for charged particle detection, time of flight, tracking and digital calorimetry due to their large signal amplitudes as well as excellent position and time resolutions. A dedicated R&D programme is currently underway to design, develop and characterise large area RPCs, ultimately leading to their large scale and low-cost production required for the ICAL detector. In essence, this thesis outlines the successful completion of designing, building and characterising large size RPCs, for the first time in India. To begin with, we developed a large number of single gap glass RPCs of 30 cm × 30 cm in area, using the glass procured from local market, and studied their operation in the streamer mode (using a gas mixture of R134a : Isobutane : Argon in the ratio of 62 : 8 : 30). The results fined from the characterisation study of these chambers were reliable with those reported in the literature. However, we were faced with a grave problem as far as stability of their operation is concerned. They died of sudden aging when operated continuously. In order to understand this problem, we studied widely the glass, gas and other mechanism of the RPC detector using a number of different method. We then fabricated a large number of RPCs of 100 cm × 100 cm in area and operated them in the avalanche mode (using a gas mixture of R134a: Isobutane: SF6 in the ratio of 95.15: 4.51: 0.34), without facing any aging problems. These chambers show typical efficiencies of over 98% and timing resolutions of about 1 ns. For the full utilization of the outstanding timing properties of the Resistive Plate Chamber (RPC), front-end electronics with unique characteristics are required. These are (1) Differential input, to profit from the differential signal from the RPC (2) A fast amplifier with less than 1 Nano-second peaking time and (3) Input charge measurement by Time- Over-Threshold (TOT) for slewing correction. An 8-channel amplifier and discriminator chip has been developed to match these necessities. This is the NINO ASIC, fabricated with 0:25 mm CMOS technology. The power requirement at 27 mW/channel is low. Results on the performance of the RPCs using the NINO ASIC are presented. Typical time resolutions of the RPC system are in the 50 Pico-second range, with an efficiency of 99:9%. The time over threshold method is used in the NINO amplifier chip in time of flight measurements in the MPD detector. For the TOF measurements MRPC detectors are used. Using a signal and noise generator the effects of the noise on the time resolution in the time over threshold method is experimentally studied.

The focus of this thesis is the development of Resistive Plate Chambers (RPCs) with ceramic electrodes. The use of ceramic composites, Si3N4/SiC, opens the way for the application of RPCs in harsh radiation environments. Future Experiments like the Compressed Baryonic Matter (CBM) at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt will need new RPCs with high rate capabilities and high radiation tolerance. Ceramic composites are specially suited for this purpose due to their resistance to radiation and chemical contamination. The bulk resistivity of these ceramics is in the range 10^7 - 10^13 Ohm cm. The bulk resistivity of the electrodes is the main factor determining the rate capabilities of a RPC, therefore a specifific measuring station and a measurement protocol has been set for these measurements. The dependence of the bulk resistivity on the difffferent steps of the manufacturing process has been studied. Other electrical parameters like the relaxation time, the relative permittivity and the tangent loss have also been investigated. Simulation codes for the investigation of RPC functionality was developed using the gas detectors simulation framework GARFIELD++. The parameters of the two mixtures used in RPC operation have been extracted. Furthermore, theoretical predictions on time resolution and effi ciency have been calculated and compared with experimental results. Two ceramic materials have been used to assemble RPCs. Si3N4/SiC and Al2O3 with a thin (nm thick) chromium layer deposited over it. Several prototypes have been assembled with active areas of 5x 5 cm^2, 10x 10 cm^2 and 20 x20 cm^2. The number of gaps ranges from two to six. The gas gap widths were 250 micro meter and 300 micrometer. As separator material mylar foils, fifishing line and high-resistive ceramics have been used. Different detector architectures have been built and their effffect on RPC performance analysed. The RPCs developed at HZDR and ITEP (Moscow) were systematically tested in electron and proton beams and with cosmic radiation over the course of three years. The performance of the RPCs was extracted from the measured data. The main parameters like time resolution, effi ciency, rate capabilities, cluster size, detector currents and avalanche charge were obtained and compared with other RPC systems in the world. A comparison with phenomenological models was performed.

This report analyzes the impact of some important factors on the prediction of detection probabilities for radiation portal monitors (RPMs). The application of innovative detection technology to improve operational sensitivity of RPMs has received increasing attention in recent decades. In particular, two alarm algorithms, gross count and energy windowing, have been developed to try to distinguish between special nuclear material (SNM) and naturally occurring radioactive material (NORM). However, the use of the two detection strategies is quite limited due to a very large number of unpredictable threat scenarios. We address this problem by implementing a new Monte Carlo radiation transport simulation approach to model a large set of threat scenarios with predefined conditions. In this report, our attention is focused on the effect of two important factors on the detected energy spectra in RPMs, the mass of individual nuclear isotopes and the thickness of shielding materials. To study the relationship between these factors and the resulting spectra, we apply several advanced statistical regression models for different types of data, including a multinomial logit model, an ordinal logit model, and a curvilinear regression model. By utilizing our new simulation technique together with these sophisticated regression models, we achieve a better understanding of the system response under various conditions. We find that the different masses of the isotopes change the isotopes’ effect on the energy spectra. In analyzing the joint impact of isotopes’ mass and shielding thickness, we obtain a nonlinear relation between the two factors and the gross count of gamma photons in the energy spectrum.
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The goal of this study was to show that quantifiable metabolic changes may be used to screen for cancer. NIH III nude mice (n=22) were injected with human GBM cells, with daily urine samples collected pre and post-injection. 14 mice were injected with saline to serve as controls. The measurement of metabolite concentrations took place on an 800 MHz NMR spectrometer. 34 metabolites were identified and quantified, through targeted profiling, with Chenomx Suite 5.1. Univariate statistical analysis showed that 3 metabolites (2-oxoglutarate, glucose and trimethylamine n-oxide) were significantly altered in the presence of tumour, while PCA and PLS-DA models found the maximum variance between the healthy and tumour-bearing groups. Receiver operating characteristic (ROC) curve analysis was applied to the data set to provide a measure of clinical utility. ROC statistics were as high as 0.85 for the analysis of individual metabolites, 0.939 for the analysis of metabolite pairs and 0.996 for PLS-DA models. These results show that metabolomics has potential as a screening tool for cancer.
Medical Physics

Tese de mestrado em Engenharia Física, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2011
O laboratório FAIR (Facility for Antiprotons and Ions Research), uma atualização dos actuais aceleradores do GSI Helmholtz Centre for Heavy Ion Researchem Darmstadt, Alemanha, vai-se tornar o maior acelerador para a física nuclear na Europa e um dos maiores do mundo. Entre as experiências planeadas para o FAIR, a colaboração R3B (Reactions with Relativistic Radioactive Beams) procura explicar as propriedades nucleares dos núcleos instáveis localizados dentro dos limites da matéria nuclear, as chamadas "drip-lines". A partir da consideração da física a ser estudada na experiência R3B, a detecção de neutrões de alta energia é essencial para a medição das muitas recções que deverão ser observadas. É portanto necessário um espectrómetro ToF de alta resolução para determinar o momento dos neutrões de alta energia resultantes da decomposição do projétil com energias num intervalo de 200 MeV a 1000 MeV. Um dos conceitos para o detector de neutrões NeuLAND é baseado em RPCs (Resistive Plate Chambers). O princípio de detecção do detector usando RPCs baseia-se na detecção de partículas carregadas criadas por chuveiros hadrónicos induzidos por neutrões em materiais. Para a otimização de um possível detector de grande área de 2 x 2 m2 construído com RPCs, várias simulações foram realizadas utilizando o Virtual Monte Carlo framework FAIRROOT. O detector foi desenhado como uma estrutura de módulos de RPCs únicos com 5 gaps de gás agrupados um após o outro num total de módulos suficientes para alcançar uma eficiência de detecção de um neutrão superior a 90%. Foram estudados diferentes materiais como conversores assim como diferentes espessuras das placas de vidro com diferentes configurações geométricas. Aqui serão apresentados os resultados das simulações realizadas assim como a avaliação do desempenho do detector completo e o desempenho de um protótipo que será testado no GSI, na primavera de 2012.
The FAIR (Facility for Antiprotons and Ions Research), a greater improvement compared to current accelerators of the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, will become the largest accelerator for nuclear physics in Europe and one of the largest in the world. Among the experiments planned for FAIR, the R3B (Reactions with Relativistic Radioactive Beams) collaboration seeks to explain the nuclear properties of unstable nuclei located within the limits of nuclear matter, the socalled \drip-lines". From the consideration of the physics cases to be studied at R3B, the detection of high energy neutrons is essential for the measurement of the many reactions to be observed. A high-resolution neutron ToF spectrometer is required to determine the momentum of high-energy neutrons resulting from the decay of the projectile with energies in the range of 200 MeV to 1000 MeV. One of the concepts for the neutron detector NeuLAND was based on Resistive Plate Chambers (RPCs). The detection principle of the detector using RPCs relies on the detection of the charged particles created by hadronic showers induced by neutrons on materials. For the optimization of a possible large area detector of 2_2 m2 made with RPCs several simulations were performed using the Virtual Monte Carlo framework FAIRROOT. The detector was design as a structure of single RPCs modules with 5 gas gaps grouped one after another into a total of modules enough to reach an efficiency of one neutron detection higher than 90%. Different materials were studied as converters as well different thickness of glass plates with different geometrical configurations. The results of the performed simulations, the evaluation of the full detector performance, and the expected performance of a prototype to be tested at GSI in the spring of 2012 are presented.

碩士
明志科技大學
工業工程與管理系碩士班
106
This research is applying Nintendo N3DS game console with the combination of display technology in plane 2D and autostereoscopic 3D characteristics. This study explored display technique, ball speed in game, and the operation time for the auto-stereoscopic 3D baseball game players on signal detection theory (SDT), receiver operating characteristic space (ROC space), visual fatigue and presence through experimental design. Twenty five participants were recruited in our full factorial experiment to investigate effects of display technique (2D, autostereoscopic 3D), ball speed (114km/hr, 138km/hr), and operation time (5 minutes, 10 minutes, and 20 minutes) on the four possibilities of SDT (hit, miss, false alarm, correct rejection), β, d’, ROC space, Simulator Sickness Questionnaire (SSQ), and Igroup Presence Questionnaire (IPQ). The results indicated that display technique was significant on hit rate, SSQ and IPQ, where higher hit rate, visual fatigue, and IPQ were found in 3D technique. The results also showed that ball speed was significant on miss rate and d’, where low miss rate and high d’ were found in 138km/hr speed. The results further demonstrated that operation time was significant on false alarm rate, correct rejection rate, d’, SSQ and IPQ, where long operation time brings better performance, expect for SSQ. Most of the points were in upper left corner and near y-coordinates of ROC space, which meant that participants’ high sensitivity was demonstrated. To sum up, this study indicated that 138km/hr speed with 3D display provided high hit rate and presence, although also having high visual fatigue. It is recommended that N3DS players may choose high speed mode and avoid long time playing, and then high visual fatigue will be avoided.

The collection of crop yield data has become much easier with the introduction of technologies such as the Global Positioning System (GPS), ground-based yield sensors, and Geographic Information Systems (GIS). This explosive growth and widespread use of spatial data has challenged the ability to derive useful spatial knowledge. In addition, outlier detection as one important pre-processing step remains a challenge because the technique and the definition of spatial neighbourhood remain non-trivial, and the quantitative assessments of false positives, false negatives, and the concept of region outlier remain unexplored. The overall aim of this study is to evaluate different spatial outlier detection techniques in terms of their accuracy and computational efficiency, and examine the performance of these outlier removal techniques in a site-specific management context. In a simulation study, unconditional sequential Gaussian simulation is performed to generate crop yield as the response variable along with two explanatory variables. Point and region spatial outliers are added to the simulated datasets by randomly selecting observations and adding or subtracting a Gaussian error term. With simulated data which contains known spatial outliers in advance, the assessment of spatial outlier techniques can be conducted as a binary classification exercise, treating each spatial outlier detection technique as a classifier. Algorithm performance is evaluated with the area and partial area under the ROC curve up to different true positive and false positive rates. Outlier effects in on-farm research are assessed in terms of the influence of each spatial outlier technique on coefficient estimates from a spatial regression model that accounts for autocorrelation. Results indicate that for point outliers, spatial outlier techniques that account for spatial autocorrelation tend to be better than standard spatial outlier techniques in terms of higher sensitivity, lower false positive detection rate, and consistency in performance. They are also more resistant to changes in the neighbourhood definition. In terms of region outliers, standard techniques tend to be better than spatial autocorrelation techniques in all performance aspects because they are less affected by masking and swamping effects. In particular, one spatial autocorrelation technique, Averaged Difference, is superior to all other techniques in terms of both point and region outlier scenario because of its ability to incorporate spatial autocorrelation while at the same time, revealing the variation between nearest neighbours. In terms of decision-making, all algorithms led to slightly different coefficient estimates, and therefore, may result in distinct decisions for site-specific management. The results outlined here will allow an improved removal of crop yield data points that are potentially problematic. What has been determined here is the recommendation of using Averaged Difference algorithm for cleaning spatial outliers in yield dataset. Identifying the optimal nearest neighbour parameter for the neighbourhood aggregation function is still non-trivial. The recommendation is to specify a large number of nearest neighbours, large enough to capture the region size. Lastly, the unbiased coefficient estimates obtained with Average Difference suggest it is the better method for pre-processing spatial outliers in crop yield data, which underlines its suitability for detecting spatial outlier in the context of on-farm research.

A Imagiologia Médica tem vindo a desenvolver-se no sentido em que se apresenta como uma ferramenta imprescindível ao diagnóstico. Nesta crescente tomada de importância aparecem técnicas de Medicina Nuclear de que é exemplo a tomografia PET. Em PET a radiação gama, proveniente da aniquilação de um positrão com um electrão, apresenta-se na forma de dois fotões emitidos em direcções diametralmente opostas, permitindo a definição de linhas de resposta onde se encerra a localização de radioactividade. Os tomógrafos PET evoluem no sentido de melhoria da resolução espacial e sensibilidade. A melhoria da resolução espacial para uma mesma relação sinal/ruído requer um grande aumento de sensibilidade. Associado a este aumento de sensibilidade aparece a necessidade de aumentar o campo de visão axial (AFOV – Axial Field of View) do tomógrafo, o que se torna insuportavelmente dispendioso com a tecnologia de cristais de cintilação acoplados a fotomultiplicadores, actualmente existente. No LIP-Coimbra tem-se investido no desenvolvimento da tecnologia PET utilizando detectores diferentes dos anteriores, os RPC’s, que podem ser construídos com maior área a um custo inferior. Com esta tecnologia perspectiva-se a construção de um tomógrafo com um longo AFOV (podendo mesmo cobrir todo o paciente). Os RPC’s têm uma eficiência menor do que os cristais cintiladores, mas essa desvantagem seria largamente compensada com o aumento do AFOV, aliada a outras vantagens, como sendo a possibilidade de TOFPET (Time-of-Flight PET). Um dos principais efeitos físicos que influenciam a aquisição em PET é o efeito Compton. Esta componente é indesejável e constitui uma grande percentagem dos eventos detectados (aumentando com o aumento do AFOV). Se não for adequadamente estimada e corrigida, pode impedir que a qualidade de imagem seja competitiva com a dos tomógrafos comerciais existentes. Este projecto visa corrigir a radiação dispersa por efeito Compton existente num tomógrafo com as características descritas. Os RPC’s não dispõem da possibilidade de medir a energia dos fotões, embora a sua eficiência de detecção varie com a energia. Com esta limitação uma simulação numérica foi implementada, a SSS, Single Scatter Simulation. O SSS é um método que se baseia na hipótese de que por cada coincidência dispersaregistada um único efeito Compton lhe está na origem. Em suma, por par de fotões provenientes da aniquilação, o efeito Compton ocorre uma única vez. Tal consideração permite simplificar consideravelmente a geometria e cálculo da distribuição de radiação dispersa. Efectuou-se a simulação, para validação do método, em meio de atenuação cilíndrico. A simulação da radiação dispersa que se sobrepõe a uma aquisição PET em contexto clínico efectuou-se recorrendo ao uso de um fantoma humano voxelizado, o NCAT. A validação da implementação foi efectuada de modo qualitativo, comparando resultados do método com simulações em Geant4 para o mesmo fantoma. Obteve-se uma concordância razoável de resultados para o método SSS e as simulações em Geant4 que indicam que o método implementado é bastante satisfatório na correcção de radiação dispersa. Uma validação mais aprofundada deverá ser realizada futuramente.

The research project consists in the analysis, design and prototyping of systems for autonomous guidance of RPAS. After a first analysis of the state of the art, available sensor technologies have been surveyed and a proper architecture of an embedded platform has been identified and designed, that aims to perform autonomous guidance of RPAS by using techniques of sense and avoid.

Dissertação de Mestrado em Segurança Informática apresentada à Faculdade de Ciências e Tecnologia
O presente trabalho visa a mitigação da problemática associada à incidência de ataques Wormhole em redes operadas pelo protocolo de encaminhamento Routing Protocol for Low-Power and Lossy Networks (RPL). Este tipo de ataque pressupõe, tipicamente, a existência de pelo menos dois nós maliciosos na topologia que mantêm entre si uma ligação privada através da qual partilham pacotes legítimos. Esta prática motiva a que os nós que se encontrem nas imediações dos nós infetados assumam, erradamente, nós distantes como seus vizinhos. Ciente das limitações energéticas e computacionais dos dispositivos Internet of Things (IoT) e dado o seu vasto domínio aplicacional, torna-se importante o desenvolvimento de estratégias que promovam a segurança desta tecnologia. Neste seguimento, foi proposto um Intrusion Detection System (IDS), híbrido, baseado em assinaturas, vocacionado à identificação de ataques Wormhole neste tipo de ambiente. A estratégia de deteção desenvolvida passa pelo relacionamento da distância percorrida pelos pacotes, entre os nós remetente e destinatário, com a distância tida como referência para esse trajeto. Dado o seu princípio, o modelo pressupõe a previa determinação da distância entre nós vizinhos, bem como, a inclusão de novos campos nos pacotes em trânsito. A avaliação do sistema de deteção, por recurso a simulação com a ferramenta Cooja, mostrou resultados bastante satisfatórios no que concerne à capacidade de deteção de ataques e identificação de nós maliciosos, apresentando ainda um impacto energético perfeitamente admissível dado o domínio em que se aplica.
The present work approaches the problem associated with the incidence of Wormhole attacks in networks operated by the Routing Protocol for Low-Power and Lossy Networks (RPL). This type of attack typically assumes the existence of at least two malicious nodes in the topology that maintain a private connection used to broadcast legitimate packets. This practice motivates nodes that are in the vicinity of the infected nodes to mistakenly assume distant nodes as their neighbours. The energy and computational limitations of Internet of Things (IoT) devices and the vast application domain where they are used, motivate the development of strategies that promote the safety of this technology. Following this, a hybrid Intrusion Detection System (IDS), based on signatures, aimed at identifying Wormhole attacks in this type of environment was proposed. The detection strategy involves the relationship of the distance travelled by the packets, between the sender and recipient nodes, with the distance taken as a reference for this path. The operationalization of this model presupposes the prior determination of the distance between neighbouring nodes, and the inclusion of new fields in the packets in transit. The proposed IDS was evaluated using simulation with the Cooja tool and showed very satisfactory results in terms of the ability to detect attacks and identify malicious nodes. Regarding the energy impact of the solution, it was perfectly acceptable given the domain in which it applies.