Trajectographie de courses de ski alpin avec GPS

Jusqu'à présent, les seules informations disponibles pour l'analyse des courses de ski se limitent aux temps intermédiaires et aux images vidéo. Bien que très spectaculaire pour le téléspectateur, une analyse vidéo (telle qua la technologie SimulCam de Darfish) ne fournit que des informations qualitatives et partielles. L'utilisation de la technique GPS permet d'obtenir des informations quantitatives très précises de trajectoire couvrant l'intégrité de la course

Heat Integration Study of CO2 Capture in Blue Hydrogen Production

Hydrogen is an energy carrier that can be used to develop a low-carbon economy: the hydrogen-based industry. For this purpose, a source of hydrogen is needed. Steam methane reforming (SMR) is the current benchmark to produce hydrogen. This technology combines high efficiency and low production cost; however, it is CO2-intensive. Integrated with carbon capture, SMR could provide a low carbon H2, (blue Hydrogen). This paper studies the potential of an offshore blue hydrogen production with heat integration allowing recovery of heat in the SMR process to use in the CO2 capture process. For the studied case, the heat integration shows that almost half of CO2 can be captured based on chemical absorption with 30wt% MEA. Finally, an economic evaluation discusses the cost of hydrogen production highlighting that CO2 taxes play a crucial role

Sensors / The effect of different Global Navigation Satellite System methods on positioning accuracy in elite alpine skiing

In sport science, Global Navigation Satellite Systems (GNSS) are frequently applied to capture athletes' position, velocity and acceleration. Application of GNSS includes a large range of different GNSS technologies and methods. To date no study has comprehensively compared the different GNSS methods applied. Therefore, the aim of the current study was to investigate the effect of differential and non-differential solutions, different satellite systems and different GNSS signal frequencies on position accuracy. Twelve alpine ski racers were equipped with high-end GNSS devices while performing runs on a giant slalom course. The skiers' GNSS antenna positions were calculated in three satellite signal obstruction conditions using five different GNSS methods. The GNSS antenna positions were compared to a video-based photogrammetric reference system over one turn and against the most valid GNSS method over the entire run. Furthermore, the time for acquisitioning differential GNSS solutions was assessed for four differential methods. The only GNSS method that consistently yielded sub-decimetre position accuracy in typical alpine skiing conditions was a differential method using American (GPS) and Russian (GLONASS) satellite systems and the satellite signal frequencies L1 and L2. Under conditions of minimal satellite signal obstruction, valid results were also achieved when either the satellite system GLONASS or the frequency L2 was dropped from the best configuration. All other methods failed to fulfill the accuracy requirements needed to detect relevant differences in the kinematics of alpine skiers, even in conditions favorable for GNSS measurements. The methods with good positioning accuracy had also the shortest times to compute differential solutions. This paper highlights the importance to choose appropriate methods to meet the accuracy requirements for sport applications.(VLID)157451

Seismic characterization of a rapidly-rising jökulhlaup cycle at the A.P. Olsen Ice Cap, NE-Greenland

Rapidly-rising jökulhlaups, or glacial outburst floods, are a phenomenon with a high potential for damage. The initiation and propagation processes of a rapidly-rising jökulhlaup are still not fully understood. Seismic monitoring can contribute to an improved process understanding, but comprehensive long-term seismic monitoring campaigns capturing the dynamics of a rapidly-rising jökulhlaup have not been reported so far. To fill this gap, we installed a seismic network at the marginal, ice-dammed lake of the A.P. Olsen Ice Cap (APO) in NE-Greenland. Episodic outbursts from the lake cause flood waves in the Zackenberg river, characterized by a rapid discharge increase within a few hours. Our 6 months long seismic dataset comprises the whole fill-and-drain cycle of the ice-dammed lake in 2012 and includes one of the most destructive floods recorded so far for the Zackenberg river. Seismic event detection and localization reveals abundant surface crevassing and correlates with changes of the river discharge. Seismic interferometry suggests the existence of a thin basal sedimentary layer. We show that the ballistic part of the first surface waves can potentially be used to infer medium changes in both the ice body and the basal layer. Interpretation of time-lapse interferograms is challenged by a varying ambient noise source distribution.ISSN:0022-1430ISSN:1727-565

Developing a fully online course for senior medical students

In 2002 the University of Michigan Medical School created a one-month course in advanced medical therapeutics (AMT). All senior medical students were required to complete the course. To provide some flexibility for students who were interviewing for residency positions the AMT course was created using a distance-learning model, and in the 2008–2009 academic year it was offered in a fully online format. The components of the course are weekly case-based modules, a weekly online seminar, quizzes based on modules and seminars, and a research project based on a therapeutic question. The paper discusses the development and components of the AMT course, a survey of fourth-year medical students who participated in the course between 2007 and 2010, and how the course evolved over three years

In situ observations of the Swiss periglacial environment using GNSS instruments

Monitoring of the periglacial environment is relevant for many disciplines including glaciology, natural hazard management, geomorphology, and geodesy. Since October 2022, Rock Glacier Velocity (RGV) is a new Essential Climate Variable (ECV) product within the Global Climate Observing System (GCOS). However, geodetic surveys at high elevation remain very challenging due to environmental and logistical reasons. During the past decades, the introduction of low-cost global navigation satellite system (GNSS) technologies has allowed us to increase the accuracy and frequency of the observations. Today, permanent GNSS instruments enable continuous surface displacement observations at millimetre accuracy with a sub-daily resolution. In this paper, we describe decennial time series of GNSS observables as well as accompanying meteorological data. The observations comprise 54 positions located on different periglacial landforms (rock glaciers, landslides, and steep rock walls) at altitudes ranging from 2304 to 4003 ma.s.l. and spread across the Swiss Alps. The primary data products consist of raw GNSS observables in RINEX format, inclinometers, and weather station data. Additionally, cleaned and aggregated time series of the primary data products are provided, including daily GNSS positions derived through two independent processing tool chains. The observations documented here extend beyond the dataset presented in the paper and are currently continued with the intention of long-term monitoring. An annual update of the dataset, available at https://doi.org/10.1594/PANGAEA.948334 (Beutel et al., 2022),​​​​​​​ is planned. With its future continuation, the dataset holds potential for advancing fundamental process understanding and for the development of applied methods in support of e.g. natural hazard management

Improving Online Interactions: Lessons from an Online Anatomy Course with a Laboratory for Undergraduate Students

An online section of a face-to-face (F2F) undergraduate (bachelor\u27s level) anatomy course with a prosection laboratory was offered in 2013-2014. Lectures for F2F students (353) were broadcast to online students (138) using Blackboard Collaborate (BBC) virtual classroom. Online laboratories were offered using BBC and three-dimensional (3D) anatomical computer models. This iteration of the course was modified from the previous year to improve online student-teacher and student-student interactions. Students were divided into laboratory groups that rotated through virtual breakout rooms, giving them the opportunity to interact with three instructors. The objectives were to assess student performance outcomes, perceptions of student-teacher and student-student interactions, methods of peer interaction, and helpfulness of the 3D computer models. Final grades were statistically identical between the online and F2F groups. There were strong, positive correlations between incoming grade average and final anatomy grade in both groups, suggesting prior academic performance, and not delivery format, predicts anatomy grades. Quantitative student perception surveys (273 F2F; 101 online) revealed that both groups agreed they were engaged by teachers, could interact socially with teachers and peers, and ask them questions in both the lecture and laboratory sessions, though agreement was significantly greater for the F2F students in most comparisons. The most common methods of peer communication were texting, Facebook, and meeting F2F. The perceived helpfulness of the 3D computer models improved from the previous year. While virtual breakout rooms can be used to adequately replace traditional prosection laboratories and improve interactions, they are not equivalent to F2F laboratories

Over de grens: Nederlands extreem geweld in de Indonesische onafhankelijkheidsoorlog, 1945-1949

Op 17 augustus 1945, twee dagen na de Japanse capitulatie, verklaarde Indonesië zich onafhankelijk. Nederland erkende dit niet en trachtte met geweld zelf de regie te voeren over het onvermijdelijke proces van dekolonisatie. Dit leidde tot vier jaren van moeizame onderhandelingen en bittere oorlogvoering. In 2005 verklaarde de Nederlandse regering dat Nederland die oorlog niet had moeten voeren. Over het geweld dat de Nederlandse militairen tijdens deze oorlog hadden toegepast, staat echter nog altijd het regeringsstandpunt uit 1969 overeind: er waren wel ‘excessen’, maar de krijgsmacht had zich in de regel ‘correct’ gedragen.Naarmate de aanwijzingen van extreem Nederlands geweld zich opstapelden, bleek dit officiële standpunt steeds moeilijker vol te houden. De Nederlandse regering besloot daarom in 2016 tot financiering van een groot onderzoeksprogramma. De belangrijkste conclusies daarvan zijn in dit boek te vinden. De auteurs maken aannemelijk dat de Nederlandse krijgsmacht op structurele basis extreem geweld toepaste en dat dit toen en ook lang daarna op allerlei manieren werd toegedekt. Dit alles past slecht bij een rooskleurig nationaal zelfbeeld – zoals eigenlijk de hele koloniale geschiedenis met dat zelfbeeld schuurt.Colonial and Global Histor