281 research outputs found
Astronomy Without a Telescope
No full textCreated by author Nick Strobel, "Astronomy Notes" is an educational resource for introductory astronomy classes for undergraduates. This section describes: the celestial sphere, coordinate systems, the motion of the stars. There are also sections describing: time, the seasons, time zones, the phases of the moon, solar eclipses, lunar eclipses, and the motions of the planets
Ein Beitrag zur Nutzbarmachung Genetischer Algorithmen für die optimale Steuerung und Planung eines flexiblen Stadtschnellbahnbetriebes
No full textThe work deals with two problems of mass rapid transit system operation: The development of flexible timetables and the realisation of flexible timetables. In both cases, genetic algorithms are used. In the process of (flexible) timetabling in suburban railways, a transport offer perfectly adapted to demand is searched for (temporal and spatial adaptation of demand as well as adaptation of capacity of the trains). After determination of the number of train runs per line and hour and their capacity, optimal departure times have to be found (with a precision of a minute down to 10 s), which fulfil criterias of the passengers (short waiting times) as well as of the operator (small number of vehicles needed). Two different codings for use with genetic algorithms have therefore been developed. They are tested on several case studies of the Dresden suburban railway network, assuming different degrees of flexibilisation. In the process of realising a flexible timetable, transitions between train headways as well as running time and dwell time reserves (margins in the order of a few seconds) are slightly modified in order to coordinate braking and accelerating trains and thereby reduce energy costs of a system of trains. Genetic algorithms can be applied for this problem as well, the proposed methods are tested on several case studies (S-Bahn Berlin, Metro Lille).Die Arbeit behandelt zwei Probleme der Betriebsplanung von Stadtschnellbahnen: Die Erstellung flexibler Fahrpläne und die Umsetzung flexibler Fahrpläne. In beiden Fällen werden zur Lösung Genetische Algorithmen verwendet. Bei der Ermittlung flexibler Fahrpläne von S-Bahnen wird ein bestmöglich an die Verkehrsnachfrage angepasstes Verkehrsangebot gesucht (zeitlich, räumlich und bezüglich der Kapazität der einzelnen Züge angepasst). Nach stundenfeiner Festlegung der Fahrtenhäufigkeiten und Kapazitäten der einzelnen, sich überlagernden Linien werden deren Abfahrtszeiten gesucht (mit einer Genauigkeit von Minuten bis etwa 10 s), so dass sowohl die Wünsche der Fahrgäste nach gleichmäßigen Zugfolgezeiten als auch Betreiberwünsche (geringe Fahrzeuganzahl) erfüllt werden. Hierzu werden zwei verschiedene Kodierungen für die Verwendung mit Genetischen Algorithmen vorgestellt und das geschaffene Verfahren an verschiedenen Flexibilisierungsszenarien für die S-Bahn Dresden erprobt. Bei der Umsetzung flexibler Fahrpläne, die sich im Bereich weniger Sekunden abspielt, werden Übergänge zwischen Zugfolgezeiten, Fahr- und Haltezeitreserven geringfügig modifiziert, so dass durch bestmögliche Koordination von Anfahr- und Bremsvorgängen eines Systems von Zügen die Energiekosten minimal werden. Methodisch werden wiederum Genetische Algorithmen verwendet, die Erprobung des Verfahrens erfolgt anhand von Linien der S-Bahn Berlin und der Metro in Lille
In situ study of hydrogen silsesquioxane dissolution rate in salty and electrochemical developers
No full textIn order to better characterize the development of the electron-beam resist hydrogen silsesquioxane (HSQ), the authors used a quartz crystal microbalance (QCM) to study its rate of dissolution in situ. The authors determined the effect of both salt concentration and applied electric potential on the development rate of HSQ. The development rates were measured by spinning HSQ directly onto a quartz crystal resonator, and then developing in a QCM microfluidic module. In order to more directly observe the effect of electric potentials on the HSQ development rate, a film of HSQ was partially cross-linked in an O2 plasma asher and then developed in the QCM flow module with a salt-free NaOH solution. As the partially cross-linked HSQ slowly developed, electric potentials were applied and removed from the crystal allowing the observation of how the development rate increased upon the application of a positive electric potential. The increased development rate caused by both the addition of salt ions and a positive electric potential suggests that the rate may be limited by a build-up of negative charge on the HSQ.QN/Quantum NanoscienceApplied Science
The importance of pancreatic inflammation in endosonographic diagnostics of solid pancreatic masses
No full textEndosonography (EUS) is one of the main diagnostic tools for the differential diagnosis of pancreatic masses. The aim of our study was to describe the value of this technique in the work-up of solid pancreatic lesions, considering the influence of the morphological evidence of pancreatic inflammation in the diagnostic process
Late Breaking Abstract - Outpatient follow-up of COPD patients receiving long-term non-invasive ventilation (OCONIV-Trial): A randomized controlled trial
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Educational standards, teacher preparation, and metacognition instruction for elementary students: Studies in pre-college engineering education
No full textThis dissertation is a compilation of three separate works representing a wide range of issues related to pre-college engineering. Each work addresses multiple levels of concern for educators from national policy to specific classroom intervention. Although presenting different styles of writing—due to different journals requirements—and various methods of research, all purpose to further research and instruction in pre-college engineering. The research detailed in these papers has been inspired by the current STEM (science, technology, engineering, and mathematics) education movement and in particular, by the National Academy of Engineering\u27s leadership in promoting the integration of engineering into pre-college classrooms (National Research Council, 2010, 2011). Combining the three studies into one dissertation provides a broad view of pre-college engineering and demonstrates the diversity of relevant methodological approaches. It also demonstrates the importance of looking at education as a complex system of people, policies, and curricula when putting research into practice. Primarily, the research and practice of instructional design depends on a cycle of design, teaching, and evaluation. The three pieces of this work represent each of these phases. Chapter 1 provides: a) discussion of how these studies connect to demonstrate instructional design and research competencies under the shared context of pre-college engineering, and b) an overview of each study. Chapter 2, Engineering in the K-12 STEM Standards of the 50 U.S. States: An Analysis of Presence and Extent (Carr, Bennett, & Strobel, 2012), was published in the July 2012 issue of The Journal of Engineering Education, the premier peer-reviewed international journal devoted to research on engineering education at all levels. The content analysis of educational standards from all 50 U.S. states found engineering in the standards of 41 states, and analysis of those standards resulted in a list of Big Ideas of doing engineering in the pre-college classroom. Chapter 3, A Design Case: Design and Integration of Engineering Curriculum for Secondary Teachers and Researchers , is in journal-ready format for a journal that exclusively features instructional design cases. The case follows the design process of graduate level course from the start of the project through two iterations and details the challenges, struggles, and decisions made to overcome them. The implementation outcomes showed improvement through the iterations and has provided the foundation for other professional development and teacher preparation courses. Chapter 4, Design and Study of MCinEDP: Metacognition for Reflective Design in Pre-College Engineering, is an evaluation study and design case of instruction designed for elementary school students participating in engineering design activities. The results of the evaluation and analysis of the implementation inform further modifications of the intervention and encourage further research. To conclude, Chapter 5 summarizes the outcomes of the studies and their effects on the author and his place in the research community
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