Exploring the DET vs MPPT Trade for CubeSat to ESPA Sized Earth-Orbiting Spacecraft

Previous research has evaluated different EPS topologies from efficiency, reliability, and cost perspectives, but has yet to incorporate orbital dynamics and mission attitude constraints into the overall evaluation of the most effective eps topology for a specific mission\u27s needs. For efficient system architecture design, systems engineers must quickly assess the orbit-average maximum load that can be accommodated based on the orbit, pointing constraints, solar array collection area, and EPS efficiency to determine operational feasibility. The authors present preliminary findings showing that attitude constraints and the inclination/β-angle have significant effects on the available energy the spacecraft can capture and the size of the load the spacecraft can support

Design of an In-Situ Sensor Package to Track CubeSat Deployments

Currently, radar measurements of low-earth-orbit CubeSats are only possible during a small portion of a CubeSat’s orbit – typically long after the CubeSat’s deployment – making near real-time space situational awareness (SSA) difficult. The CU Boulder Smead Aerospace Engineering Department has developed a concept to monitor CubeSat deployments from the deployer itself and provide relative position and velocity measurements of deployed payloads to provide faster orbital parameter estimation. Teaming with NanoRacks LLC, the VANTAGE team (Visual Approximation of Nanosat Trajectories to Augment Ground-based Estimation) has developed an innovative sensor package prototype consisting of an Infra-red (IR) Time of Flight (ToF) camera for close-range CubeSat position measurements and a monochrome optical camera for continued detection and in-plane position refinement, as well as a set of algorithms to process and fuse these CubeSat position measurements. These sensors and their avionics are incorporated into a prototype integrated system designed to fit within a single 6U CubeSat Deployment silo on the NanoRacks ISS deployer, enabling the detection, identification, and tracking of up to 6 CubeSats out to 100m with a maximum positional error of 10m within 15 minutes of deployment

CSAC Flight Experiment to Characterize On-Orbit Performance

Precise positioning, navigation, and timing requirements are driving a need for increasingly accurate spacecraft timing systems. This paper describes an experiment being developed at the University of Colorado Boulder to quantify the stability and behavior of a chip-scale atomic clock (CSAC) onboard an Air Force Research Laboratory (AFRL) University Nanosatellite Program (UNP-9) MAXWELL CubeSat mission. The CSAC experiment will run onboard MAXWELL, enabling the GPS receiver measurements to occur using the unsteered CSAC as an external clock. The experiment will record and downlink the position, clock bias, pseudorange, phase, and temperature. These data will allow us to characterize the on-orbit performance of the CSAC

A Methodology for Successful University Graduate CubeSat Programs

The University of Colorado Smead Department of Aerospace Engineering has over a decade of success in designing, building, and operating student led CubeSat missions. The experience and lessons learned from building and operating the CSSWE, MinXSS-1, MinXSS-2, and QB50-Challenger missions have helped grow a knowledge base on the most effective and efficient ways to manage some of the “tall poles” when it comes to student run CubeSat missions. Among these “tall poles” we have seen student turnover, software, and documentation become some of the hardest to knock-down and we present our strategies for doing so. We use the MAXWELL mission (expected to launch in 2021) as a road-map to detail the methodology we have built over the last decade to ensure the greatest chance of mission success

Predictors and prognosis of paroxysmal atrial fibrillation in general practice in the UK

BACKGROUND: Natural history of paroxysmal atrial fibrillation (AF) is not very well documented. Clinical experience suggests that paroxysmal AF could progress to chronic AF with estimates ranging between 15 and 30% over a period of 1–3 years. We performed an epidemiologic study to elucidate the natural history of paroxysmal AF, this study estimated its incidence in a general practice setting, identified associated factors and analyzed the progression into chronic AF as well as the mortality rate. METHODS: Using the UK General Practice Research Database (GPRD), we identified patients aged 40–89 years with a first-recorded episode of paroxysmal AF during 1996. Risk factors were assessed using 525 incident paroxysmal AF cases confirmed by the general practitioner (GP) and a random sample of controls. We follow-up paroxysmal AF patients and estimated their mortality rate and progression to chronic AF. RESULTS: The incidence of paroxysmal AF was 1.0 per 1,000 person-years. Major risk factors for paroxysmal AF were age and prior valvular heart disease, ischaemic heart disease, heart failure and hyperthyroidism. During a mean follow-up of 2.7 years, 70 of 418 paroxysmal AF patients with complete information progressed to chronic AF. Risk factors associated with progression were valvular heart disease (OR 2.7, 95% CI 1.2–6.0) and moderate to high alcohol consumption (OR 3.0, 95% CI 1.1–8.0). Paroxysmal AF patients did not carry an increased risk of mortality, compared to an age and sex matched sample of the general population. There was a suggestion of a small increased risk among patients progressing to chronic AF (RR 1.5, 96% CI 0.8–2.9). CONCLUSION: Paroxysmal AF is a common arrhythmia in the general practice setting, increasing with age and commonly associated with other heart diseases. It sometimes is the initial presentation and then progress to chronic AF. A history of valvular heart disease and alcohol consumption are associated with this progression

Protocoles chirurgicaux d'accélération du déplacement orthodontique : innovations ou illusions ?/revue de la littérature/thèse présentée pour le diplôme d'État de docteur en chirurgie dentaire le 19.04.2021

Chirurgie dentaireLa durée moyenne des traitements actifs en Orthopédie Dento-Faciale est d’environ 2 ans. Elle représente une composante essentielle dans l’acceptation de telles thérapeutiques en particulier pour les patients adultes, souvent demandeurs de traitements courts. Les techniques chirurgicales d’accélération orthodontique, par la réalisation de corticotomies, sont connues depuis le XIXème siècle, mais jusqu’à peu de temps, elles sont restées relativement invasives, souvent inconfortables pour le patient en termes de suites postopératoires, et leur mise en oeuvre était chronophage et onéreuse. Elles étaient donc réservées à de rares cas, pratiquées par des chirurgiens oraux spécialisés et se heurtaient à une acceptation relativement limitée auprès des patients mais aussi à une certaine réticence des praticiens eux-mêmes. Des techniques innovantes et moins invasives ont vu le jour, impliquant un allègement peropératoire et postopératoire, une réduction du coût, et une efficacité proche voire équivalente aux corticotomies classiques. La corticision, la micro-ostéoperforation ou encore la piézocision en sont des exemples. Notre objectif est de répondre à la question suivante : quel protocole le chirurgien oral peut-il proposer à ses confrères spécialistes orthodontistes et à leurs patients pour promouvoir le déplacement dentaire provoqué avec un rapport bénéfices/risques positif pour le patient