Made available in DSpace on 2014-10-09T12:26:57Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:20Z (GMT). No. of bitstreams: 0 / Este trabalho apresenta uma metodologia para a caracterização das qualidades de radiação X, seguindo as novas recomendações do International Electrotechical Commission (IEC) com a norma 61267, para a implantação de um novo procedimento de calibração de sistemas dosimétricos utilizados na área de radiodiagnóstico. As qualidades de radiação de referência: RQR 2 a RQR 10, RQA 2 a RQA 10, RQB 2 a RQB 10 e RQN 2 a RQN 10 foram implantadas no laboratório de calibração do IPEN (LCI). Suas características foram analisadas por meio de medidas dos parâmetros destes feixes como: a tensão de pico prático (PPV), filtrações adicionais específicas para cada qualidade de radiação, 1ª e 2ª camadas semi-redutoras e coeficiente de homogeneidade. Para os filtros adicionais, foi utilizado alumínio de alta pureza em torno de 99,9%. A filtração inerente do tubo de raios X também foi determinada. Com a implantação destas qualidades de radiação, o LCI estará pronto para calibrar os instrumentos medidores de radiação nas novas qualidades recomendadas, permitindo assim, uma melhoria na qualidade dos serviços radiológicos que o IPEN oferece para todo o País. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Risk prediction models are important tools intended to help clinicians make optimal treatment decisions. They are often developed on large reference samples for applications in different local cohorts. For example, consider transporting the US Framingham risk prediction function for coronary heart disease (CHD) to populations in Europe or Asia. In this process it is necessary to correctly re-calibrate the existing function for future applications. In this thesis we propose a new re-calibration method which could be used when transporting the risk function from a reference to the local cohort. This new method is compared with the existing re-calibration methods through numerical simulations under various assumptions and on real-life population data. In a majority of settings it outperforms the existing methods. We also explore the strengths and limitations of each re-calibration method and provide guidance for practical use of these methods. The re-calibration methods described can be used for any risk prediction models based on Cox proportional hazard regression. To facilitate convenient application we present an easy to use SAS macro. Another essential feature of a successful risk prediction model is characterized by its discrimination or its ability to separate those with events from those without events. One of the most popular measures of discrimination is the area under the Receiver Operating Characteristic (ROC) curve, often called the c statistic or just area under the curve (AUC). Various authors have extended the AUC from binary outcome applications to survival data. However, these extensions are not unique. In this thesis we compare four of these extensions using simulations and practical applications to the Framingham risk functions as well as a breast cancer risk model. We conclude that the extension proposed by Harrell and described in detail by Pencina & D'Agostino is a metric that is most consistent with the most appropriate definition of discrimination in survival. We construct a SAS code for its consistent estimator based on the work of Uno et al. We also notice large differences in magnitude between various C indices calculated on the same data and caution against comparisons across different C indices.

Les robots sériels de grandes dimensions apportent dextérité, répétabilité et flexibilité dans les chaînes de production. Sur ces chaînes, des opérations telles que la mesure de pièces peuvent exploiter ces avantages très attractifs. Il est cependant impératif de mieux maîtriser le positionnement de l’effecteur de ces robots, pour répondre aux exigences de la mesure 3D. Dans ce contexte, une cellule de numérisation robotisée a été développée, exploitant un robot sériel 6 axes comme support d’un capteur laser plan (KZ25 Kreon), et utilisant un système de stéréovision externe pour le suivi de l’opération et la calibration de la cellule (C-Track Creaform). La calibration que nous proposons pour cette cellule permet de maîtriser la qualité et d’optimiser la vitesse de numérisation, et se veut à la fois rapide et pratique (peu de contraintes et de matériel) pour répondre à un contexte industriel.Cette calibration passe par l’identification des paramètres d’un modèle géométrique pour le robot, à l’aide d’une nouvelle méthode que nous proposons, généralisant le concept d’étude d’arc de cercle proposé dans la méthode CPA (Circle Point Analysis). Une étude comparative démontre les avantages de cette nouvelle méthode par rapport aux méthodes classiquement utilisées. Une méthode de sélection que nous avons développée permet ensuite de compléter le modèle du robot avec des paramètres non-géométriques pertinents (flexibilités, jeux). Au cours de la calibration, nous étudions également les capacités du robot en vitesse et en qualité de positionnement au travers d’indices de performance originaux. Enfin nous avons élaboré et validé une méthode de calibration en position et orientation du KZ25 sur son support (le robot) ce qui permet une numérisation à 6 DDL.En perspective, un générateur de trajectoires, à donner en consigne au robot, devra utiliser cette calibration de la cellule entière pour maîtriser la qualité de la numérisation et optimiser sa durée. / Serial robots are designed for repetitive tasks in wide workspaces, and provide good dexterity and flexibility to production lines. Restrictive applications such as parts digitizing can make use of those attractive benefits. However, digitizing needs on accuracy require to work carefully on the quality of the robot end-effector positioning. In this context, a digitizing cell using a 6 axis robot as displacement system for a laser plane sensor (KZ25) was developed. In this cell all calibrations are ensured by an external measurement system (C-Track Creaform) following the end-effector. The goal is to master the digitizing quality and to optimize the operating speed thanks to quick and convenient calibrations (few equipment, installation and constraints).First, the parameters of the robot geometric model are identified with a quick and convenient method we developed, based on the existing circle point analysis method (CPA). A comparative study shows the advantages of our identification method over classic methods. Then a selective method we proposed allows us to complete this geometric model with relevant non-geometric parameters such as flexibilities or backlashes. Robot performances in terms of speed and posing quality are also studied through new performance indexes. Finally, we had to create and validate a calibration method for the position and orientation of the KZ25 sensor in order to exploit the unrestricted orientation provided by the robot end- effector.In our work prospects, a path generation strategy will use those calibrations to create paths for the robot, with mastered digitizing quality and optimized speed.

We propose a methodology for calibrating the activity space and the cameras involved in video capture systems for upper extremity stroke rehabilitation. We discuss an in-home stroke rehabilitation system called Semi-Automated Rehabilitation At Home System (SARAH) and a clinic-based system called Action Research Arm Test (ARAT) developed by the Interactive Neuro-Rehabilitation Lab (INR) at Virginia Tech. We propose a calibration workflow for achieving invariant video capture across multiple therapy sessions. This ensures that the captured data is less noisy. In addition, there is prior knowledge of the captured activity space and patient location in the video frames provided to the Computer Vision algorithms analyzing the captured data. Such a standardized calibration approach improved machine learning analysis of patient movements and a higher rate of agreement across multiple therapists regarding the captured patient performance. We further propose a Multi-Camera Calibration approach to perform stereo camera calibration in SARAH and ARAT capture systems to help perform a 3D reconstruction of the activity space from 2D videos. The importance of the proposed activity space and camera calibration workflows, including new research paths opened as a result of our approach, are discussed in this thesis. / Master of Science / In this thesis, I describe the workflows I developed to perform calibration of stroke rehabilitation activity spaces, including the calibration of cameras involved in video capture systems for analyzing patient movements in stroke rehabilitation practices. The proposed workflows are designed to facilitate convenient user involvement in calibrating the video capture systems to provide invariant and consistent video captures, including the extraction of fine-grain information utilizing camera calibration results, to the therapists and computer vision-based automated systems for improved analysis of patient performance in stroke rehabilitation practices. The importance of human-in-the-loop systems, including future research paths to strengthen the symbiotic relationship between humans and Artificial Intelligence systems in stroke rehabilitation practices, is discussed. The quantitative and qualitative results generated from the workshops conducted to test and evaluate the calibration workflows align with the stakeholder's needs in stroke rehabilitation systems.

Three systematic instrumental errors exist in electronic distance measuring instruments (EDMI): 1) scale error, 2) constant offset error, and 3) cyclic error. The potential magnitude of these errors requires that each EDMI should be calibrated for all three errors. The calibration constants of EDMI may be monitored on an arbitrary base line; however, a calibrated base line is required to perform an accurate EDMI calibration for constant offset and scale errors. Calibration of cyclic error requires monumentation not normally found on a calibration base line. Cyclic error can be measured on a short base line in the laboratory. The surveyors in the State of Virginia would benefit from a statewide network of calibrated base lines. A network covering the state would provide convenient access for the state's surveyors. A unified network of base lines would give the states surveyors a standard of comparison for their EDMI. This standard of comparison would be nationwide if Virginia would choose the National Geodetic Survey (NGS) to calibrate the base lines in its network. Base line calibration by NGS would require that the state abide by NGS specifications for establishing its base line network. / M.S.

A solar spectroradiometer is an instrument used for measuring the transmitted solar radiation on a quasi-continuous basis. An existing computer controlled solar spectroradiometer system has been modified and made operable. Test measurements have shown that the signal to noise ratio (which is time of day and wavelength dependent) is at an acceptable level. The chief use of the spectroradiometer will be for atmospheric transmittance studies, which will require calibration of the instrument. Strategies for calibrating the instrument have been discussed.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A long standing problem in telemetry post processing is the application of correct calibration factors to telemetered data generated on a system which has had a history of hardware changes. These calibration problems become most exacerbated when old test data is being examined and there is uncertainty as to hardware configuration at the time of the test. In this paper a mechanism for introducing a high degree of reliability in the application of calibration factors is described in an implementation done for Brilliant Pebbles Flight Experiment Three (FE-3).

published_or_final_version / Physics / Master / Master of Philosophy

No description available.

Isotropic radiators are known to be a useful tool across a wide range of applications, from applications in light dosimetry in human/animal tissue to calibration of sensitive laboratory equipment. While the bene ts are known, constructing such a tool has proven to be di cult. Currently, there are no commercially available isotropic or nearly isotropic radiators. Previous attempts at constructing an isotropic radiator have been limited to a 10% isotropy level. This thesis covers the design, construction, and analysis of a nearly isotropic optical light source. The constructed source has extrema anisotropies, over a solid angle of approximately 3 steradians, of +\-3% (with 95% of that solid angle being within +\- 2.5% anisotropy). / Graduate