The resolution of CMOS image sensor is becoming higher and higher, while for identifying its performance, designers need to do a series of simulations, and this work consumes large CPU time in classical design environment. This thesis titled "Fast Scalable and Variability Aware CMOS Image Sensor Simulation Methodology" is dedicated to explore a new simulation methodology for improving the simulation capability. This simulation methodology is used to study the image sensor performance versus low level design parameter, such as transistor size and process variability. The simulation methodology achieves error less than 0.4% on 3T-APS architecture. The methodology is tested in various pixel architectures, and it is used in simulating image sensor with 15 million pixels, the simulation capability is improved 64 times and time consumption is reduced from days to minutes. The potential application includes simulating array-based circuit, such as memory circuit matrix simulation.

Um das Entdeckungspotential des Large Hadron Colliders auszunutzen, wird er beginnend 2024 zum High Luminosity Large Hadron Collider ausgebaut. Neue Detektorherausforderungen entstehen durch die höhere instantane Luminosität und den höheren Teilchenfluss. Der neue ATLAS Inner Tracker wird den aktuellen Spurdetektor ersetzen, um mit diesen Herausforderungen umzugehen. Es gibt viele Pixeldetektortechnologien zur Teilchenspurerkennung, jedoch muss ihre Eignung für den ATLAS Inner Tracker untersucht werden. Aktive Hochspannungs-CMOS-Sensoren, die in industriellen Prozessen produziert werden, bieten eine schnelle Auslese und Strahlenhärte. In dieser Arbeit wird der HV2FEI4v2-Sensor, der kapazitiv mit dem ATLAS-FE-I4-Auslesechip gekoppelt ist, dahingehend charakterisiert, ob er für eine Verwendung in einer der äußeren Lagen des ATLAS Inner Tracker geeignet ist. Schlüsselgrößen des Prototypens, wie die Treffereffizienz und die Subpixelentschlüsselung, werden untersucht. Der frühe HV2FEI4v2-Prototyp zeigt vielversprechende Ergebnisse, die als Ausgangspunkt für weitere Entwicklungen dienen. Aktive CMOS-Sensoren stellen einen möglichen Kandidaten für einen kosteneffizienten Detektor für den High Luminosity Large Hadron Collider.

Dust storms are one of the natural hazards, which have increased in frequency in the recent years over Sahara desert, Australia, the Arabian Desert, Turkmenistan and northern China, which have worsened during the last decade. Dust storms increase air pollution, impact on urban areas and farms as well as affecting ground and air traffic. They cause damage to human health, reduce the temperature, cause damage to communication facilities, reduce visibility which delays both road and air traffic and impact on both urban and rural areas. Thus, it is important to know the causation, movement and radiation effects of dust storms. The monitoring and forecasting of dust storms is increasing in order to help governments reduce the negative impact of these storms. Satellite remote sensing is the most common method but its use over sandy ground is still limited as the two share similar characteristics. However, satellite remote sensing using true-colour images or estimates of aerosol optical thickness (AOT) and algorithms such as the deep blue algorithm have limitations for identifying dust storms. Many researchers have studied the detection of dust storms during daytime in a number of different regions of the world including China, Australia, America, and North Africa using a variety of satellite data but fewer studies have focused on detecting dust storms at night. The key elements of this present study are to use data from the Moderate Resolution Imaging Spectroradiometers on the Terra and Aqua satellites to develop more effective automated method for detecting dust storms during both day and night and generate a MODIS dust storm database.

En opération depuis 2008, l’expérience ATLAS est la plus grande de toutes les expériences au LHC. Les détecteurs ATLAS- MPX (MPX) installés dans ATLAS sont basés sur le détecteur au silicium à pixels Medipix2 qui a été développé par la collaboration Medipix au CERN pour faire de l’imagerie en temps réel. Les détecteurs MPX peuvent être utilisés pour mesurer la luminosité. Ils ont été installés à seize différents endroits dans les zones expérimentale et technique d’ATLAS en 2008. Le réseau MPX a recueilli avec succès des données indépendamment de la chaîne d’enregistrement des données ATLAS de 2008 à 2013. Chaque détecteur MPX fournit des mesures de la luminosité intégrée du LHC. Ce mémoire décrit la méthode d’étalonnage de la luminosité absolue mesurée avec les détectors MPX et la performance des détecteurs MPX pour les données de luminosité en 2012. Une constante d’étalonnage de la luminosité a été déterminée. L’étalonnage est basé sur technique de van der Meer (vdM). Cette technique permet la mesure de la taille des deux faisceaux en recouvrement dans le plan vertical et horizontal au point d’interaction d’ATLAS (IP1). La détermination de la luminosité absolue nécessite la connaissance précise de l’intensité des faisceaux et du nombre de trains de particules. Les trois balayages d’étalonnage ont été analysés et les résultats obtenus par les détecteurs MPX ont été comparés aux autres détecteurs d’ATLAS dédiés spécifiquement à la mesure de la luminosité. La luminosité obtenue à partir des balayages vdM a été comparée à la luminosité des collisions proton- proton avant et après les balayages vdM. Le réseau des détecteurs MPX donne des informations fiables pour la détermination de la luminosité de l’expérience ATLAS sur un large intervalle (luminosité de 5 × 10^29 cm−2 s−1 jusqu’à 7 × 10^33 cm−2 s−1 . / In operation since 2008, the ATLAS experiment is the largest of all the experiments at the LHC. The ATLAS-MPX (MPX) detectors installed in ATLAS are based on the Medipix2 silicon pixelated detector which has been developed by the Medipix Collaboration at CERN to perform real-time imaging. They can be used for luminosity measurements. They were installed at sixteen different positions in the ATLAS cavern at the LHC in 2008. The MPX network successfully collected data independently of the ATLAS data recording chain from 2008 to 2013. Each MPX detector provides measurements of the integrated LHC luminosity. This thesis describes the technique for calibrating the luminosity data and performance of MPX detectors for measuring the luminosity in 2012. The calibration was performed via the van der Meer (vdM) scans technique which allows the measurement of the convolved beam sizes in the vertical and the horizontal planes at the ATLAS interaction point (IP1). The determination of the absolute luminosity requires a precise knowledge of the beam intensities and the number of beam bunches. A luminosity calibration constant was determined. The three calibration scans were analyzed and the results were cross-checked among the MPX detectors and other ATLAS sub-detectors specifically dedicated to luminosity measurement. The luminosity determined from the calibration scans was compared to the luminosity of regular runs before and after the vdM scans. The MPX network gives reliable information for the overall ATLAS luminosity determination over a wide dynamic range (luminosity from 5 × 10^29 cm−2 s−1 up to 7 × 10^33 cm−2 s−1).

The term“Digital X-ray Imaging" refers to a variety of technologies that electronically capture x-ray images. Once captured the images may be electronically processed, stored, displayed and communicated. Digital imaging has the potential to overcome weaknesses inherent in traditional screen-film imaging, with high detection efficiency, high dynamic range and the capability for contrast enhancement. Image processing also makes possible innovative techniques such as computer-aided diagnosis, tomosynthesis, dual-energy imaging, and digital subtraction imaging. Several different approaches to digital imaging are being studied, and in some cases, have been developed and are being marketed. Common to all these approaches are a number of technological and medical issues to be resolved. One of the technological issues is the optimal pixel size for any particular image sensor technology. In general, the spatial resolution of the digital image is limited by the pixel size. Unfortunately while reducing pixel size improves spatial resolution this comes at the expense of signal to noise ratio (SNR). In a scintillator-charge-coupled device (CCD) system, the signal can be increased by improving the efficiency of the scintillator or by reducing noise. This study used a very low noise CCD to determine if image quality, as indicated by the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE), could be maintained while reducing pixel size. Two scintillators, one a commonly used radiographic screen the other a thallium doped cesium iodide scintillator, were used and the results compared. The results of this study show that image quality can be maintained as pixel size is reduced and that high DQE can be attained and maintained over a wide range of spatial frequencies with a well designed scintillator.

Changes in land use and land cover are associated with many environmental issues observed on the earth’s surface. In the last decades, these changes were unprece-dented, mainly in tropical forest areas. The Brazilian Amazon, the world’s largest tropical forest, lost around 200.000 km² of primary forest in the last ten years (INPE, 2005). Considering this, and the consequences caused by this deforestation, it is important to know and define correctly the responsible agents, aiming at better pub-lic policies that can help preserve the forest. Searching for indicators that could help to identify the deforestation agents, some studies, such as Mertens and Lambin (1997), suggest that every deforestation process shapes the forest land in a specific way, producing a spatial pattern that can be interpreted as indicative of the agents with specific economic activities. Based on this hypothesis, the objective of this study was to contribute to a better understanding of land change processes in the Amazon forest, investigating the linkages between spatial patterns of deforestation, as visualized in satellite images, and different agents and their specific economic activities. To reach this objective, our methodological approach was based on socio-economic data acquired at a household level combined with data from satellite im-ages. First, different spatial patterns of deforestation were identified on the satellite images, based on the typologies proposed by Husson et al. (1995). Then, some of the identified spatial patterns were isolated and analyzed for specific aspects, such as, the deforestation rate calculated through satellite images. socio-economic character-istics based on household survey data and evolution of land use and land cover based on thematic maps derived from satellite images. In addition, cluster analysis was applied using the socio-economic data (household survey) and land use and land cover data (satellite images) in a search for homogeneous groups related to the spa-tial pattern. In the end, an Analysis of Variance (ANOVA) was applied to confirm the differences between spatial patterns. The results suggested that the different spatial patterns of deforestation found in the study area can be related to specific economic activities. Nevertheless, the re-sults have indicated that the spatial configuration is not a consequence of its main economic activity. They suggest that the spatial configuration is linked to the settle-ment project, and the main economic activity in the spatial patterns is a consequence of a set of factors such as: size of property, location and disposition of the property, presence or absence of infrastructure (road, market, transportation, economic and technical).

Hybrid pixel detectors have been demonstrated to provide excellent quality detection of ionising photon radiation, particularly in X-ray imaging. Recently, there has been interest in developing a hybrid pixel detector specifically for photon dosimetry. This thesis is on the design, implementation, and preliminary characterisation of the Dosepix readout chip. Dosepix has 256 square pixels of 220 mm side-length, constituting 12.4 mm2 of photo-sensitive area per detector. The combination of multiple pixels provides many parallel processors with limited input flux, resulting in a radiation dose monitor which can continuously record data and provide a real-time report on personal dose equivalent. Energy measurements are obtained by measuring the time over threshold of each photon and a state machine in the pixel sorts the detected photon event into appropriate energy bins. Each pixel contains 16 digital thresholds with 16 registers to store the associated energy bins. Preliminary measurements of Dosepix chips bump bonded to silicon sensors show very promising results. The pixel has a frontend noise of 120 e-. In low power mode, each chip consumes 15 mW, permitting its use in a portable, battery-powered system. Direct time over threshold output from the hybrid pixel detector assembly reveal distinctive photo-peaks correctly identifying the nature of incident photons, and verification measurements indicate that the pixel binning state machines accurately categorise charge spectra. Personal dose equivalent reconstruction using this data has a flat response for a large range of photon energies and personal dose equivalent rates.

No description available.

Cette étude évalue le potentiel, comme détecteur de rayons X, des capteurs à pixel CMOS conçus pour la trajectométrie des particules chargée. Nous démontrons l'intérêt de la construction d'une image par comptage de photons uniques pour la définition de celle-ci. Un dispositif exploitant une source X est développé pour mesurer la résolution spatiale sur l'impact des photons. Une simulation complète sous GEANT4 montre que le système permet d'estimer cette résolution avec une incertitude de 2 µm. L'application du protocole caractérise la détection directe des rayons X de basse énergie (< 10 keV) par un capteur CMOS avec une résolution de 52 lp/mm. Une méthode de détection indirecte, couplant un cristal de CsI(Tl) finement segmenté au capteur CMOS, est employée pour les énergies supérieures à 10 keV. La résolution spatiale dans ces conditions atteint 15 lp/mm. Une simulation détaillée explique cette performance limitée par les caractéristiques d'émission de lumière du cristal employé.

En opération depuis 2008, l’expérience ATLAS est la plus grande de toutes les expériences au LHC. Les détecteurs ATLAS- MPX (MPX) installés dans ATLAS sont basés sur le détecteur au silicium à pixels Medipix2 qui a été développé par la collaboration Medipix au CERN pour faire de l’imagerie en temps réel. Les détecteurs MPX peuvent être utilisés pour mesurer la luminosité. Ils ont été installés à seize différents endroits dans les zones expérimentale et technique d’ATLAS en 2008. Le réseau MPX a recueilli avec succès des données indépendamment de la chaîne d’enregistrement des données ATLAS de 2008 à 2013. Chaque détecteur MPX fournit des mesures de la luminosité intégrée du LHC. Ce mémoire décrit la méthode d’étalonnage de la luminosité absolue mesurée avec les détectors MPX et la performance des détecteurs MPX pour les données de luminosité en 2012. Une constante d’étalonnage de la luminosité a été déterminée. L’étalonnage est basé sur technique de van der Meer (vdM). Cette technique permet la mesure de la taille des deux faisceaux en recouvrement dans le plan vertical et horizontal au point d’interaction d’ATLAS (IP1). La détermination de la luminosité absolue nécessite la connaissance précise de l’intensité des faisceaux et du nombre de trains de particules. Les trois balayages d’étalonnage ont été analysés et les résultats obtenus par les détecteurs MPX ont été comparés aux autres détecteurs d’ATLAS dédiés spécifiquement à la mesure de la luminosité. La luminosité obtenue à partir des balayages vdM a été comparée à la luminosité des collisions proton- proton avant et après les balayages vdM. Le réseau des détecteurs MPX donne des informations fiables pour la détermination de la luminosité de l’expérience ATLAS sur un large intervalle (luminosité de 5 × 10^29 cm−2 s−1 jusqu’à 7 × 10^33 cm−2 s−1 . / In operation since 2008, the ATLAS experiment is the largest of all the experiments at the LHC. The ATLAS-MPX (MPX) detectors installed in ATLAS are based on the Medipix2 silicon pixelated detector which has been developed by the Medipix Collaboration at CERN to perform real-time imaging. They can be used for luminosity measurements. They were installed at sixteen different positions in the ATLAS cavern at the LHC in 2008. The MPX network successfully collected data independently of the ATLAS data recording chain from 2008 to 2013. Each MPX detector provides measurements of the integrated LHC luminosity. This thesis describes the technique for calibrating the luminosity data and performance of MPX detectors for measuring the luminosity in 2012. The calibration was performed via the van der Meer (vdM) scans technique which allows the measurement of the convolved beam sizes in the vertical and the horizontal planes at the ATLAS interaction point (IP1). The determination of the absolute luminosity requires a precise knowledge of the beam intensities and the number of beam bunches. A luminosity calibration constant was determined. The three calibration scans were analyzed and the results were cross-checked among the MPX detectors and other ATLAS sub-detectors specifically dedicated to luminosity measurement. The luminosity determined from the calibration scans was compared to the luminosity of regular runs before and after the vdM scans. The MPX network gives reliable information for the overall ATLAS luminosity determination over a wide dynamic range (luminosity from 5 × 10^29 cm−2 s−1 up to 7 × 10^33 cm−2 s−1).