11,754 research outputs found

    Virginia Earth Science Collaborative Astronomy Course for Teachers

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    We describe the development and implementation of a professional development course for teachers of grades 4-12 designed to increase their content knowledge in astronomy, space science, and the nature of science using interactive presentations, and hands-on and inquiry-based lessons. The course, Space Science for Teachers, encompasses the astronomy and nature of science components of the Virginia Standards of Learning for grades 4-12 [1]. In addition to increasing their content knowledge, teachers gain experience using innovative teaching technologies, such as an inflatable planetarium, planetarium computer software, and computer controlled telescopes. The courses included evening laboratory sessions where teachers learned the constellations, how to find specific celestial objects, and how to use a variety of small telescopes. Participants received three graduate credit hours in science after completing the course requirements. Space Science for Teachers was taught at the University of Virginia in Summer 2005 and 2006, at George Mason University in Summer 2006 and 2007, at the University of Virginia Southwest Center in Abingdon, Virginia in Fall 2006, and at the MathScience Innovation Center in Richmond during Summer 2005 and 2007. A total of 135 teachers participated in the courses

    Evolution and turnover in scaling systems

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    Scaling has been discovered in the long tails of size distributions characterizing a variety of diverse systems, many of which evolve in terms of the size of their components through competition. Such time-invariant macro distributions, however, often obscure the micro-dynamics of change, such as continual turnover in the rank order of the constituents. Here we show how a model drawn from evolutionary theory can explain this change, such that the time spent in the top ranked constituents is finite and also characterized by longtailed distributions. To show the broad applicability of this model, we compare typical model runs to real-world examples including US boys’ names, UK Number One for pop albums, journal article keywords, and city sizes

    Meteorology and Cimatology: On-Line Weather Studies

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    Through the Virginia Earth Science Collaborative (VESC), a partnership of nine institutes of higher education, non-profit organizations, and eighty-three school divisions, a 3-credit, graduate-level meteorology course was offered six times between Spring 2006 and Fall 2007. The course, entitled Meteorology, was offered at three locations (Richmond, Abingdon, and Harrisonburg), and a local instructor facilitated each section. Funding for the course development, instructor stipends, and participant expenses (including travel, meals, and tuition) was provided through a competitive Mathematics and Science Partnership (MSP) grant funded through the federal No Child Left Behind legislation of 2001. The framework of the course was the American Meteorological Society\u27s Online Weather Studies program, which provides meteorological content and laboratory investigations, and relies heavily on the use of Internet-accessed, real-time weather data to teach meteorological topics in a distance learning format. The 115 teacher participants were required to complete text readings and written assignments, conduct laboratory investigations, design projects using real—time meteorological data, complete exams, and attend three face-to-face meetings. For the purpose of the VESC grant evaluation, pre-test and post-test data were collected on 110 of the participants which indicated an average 14.7% increase in participants‘ content knowledge and use of real-time meteorological products (weather maps, satellite images, station models, etc.) in their instructional delivery

    Generic guide concepts for the European Spallation Source

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    The construction of the European Spallation Source (ESS) faces many challenges from the neutron beam transport point of view: The spallation source is specified as being driven by a 5 MW beam of protons, each with 2 GeV energy, and yet the requirements in instrument background suppression relative to measured signal vary between 10−6^{-6} and 10−8^{-8}. The energetic particles, particularly above 20 MeV, which are expected to be produced in abundance in the target, have to be filtered in order to make the beamlines safe, operational and provide good quality measurements with low background. We present generic neutron guides of short and medium length instruments which are optimized for good performance at minimal cost. Direct line of sight to the source is avoided twice, with either the first point out of line of sight or both being inside the bunker (20\,m) to minimize shielding costs. These guide geometries are regarded as a baseline to define standards for instruments to be constructed at ESS. They are used to find commonalities and develop principles and solutions for common problems. Lastly, we report the impact of employing the over-illumination concept to mitigate losses from random misalignment passively, and that over-illumination should be used sparingly in key locations to be effective. For more widespread alignment issues, a more direct, active approach is likely to be needed

    MeV Neutron Production from Thermal Neutron Capture in {6}^Li Simulated with Geant4

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    Various Li compounds are commonly used at neutron facilities as neutron absorbers. These compounds provide one of the highest ratios of neutron attenuation to Îł\gamma-ray production. Unfortunately, the usage of these compounds can also give rise to fast neutron emission with energies up to almost 16 MeV. Historically, some details in this fast neutron production mechanism can be absent from some modeling packages under some optimization scenarios. In this work, we tested Geant4 to assess the performance of this simulation toolkit for the fast neutron generation mechanism. We compare the results of simulations performed with Geant4 to available measurements. The outcome of our study shows that results of the Geant4 simulations are in good agreement with the available measurements for 6^6Li fast neutron production, and suitable for neutron instrument background evaluation at spallation neutron sources.Comment: 6 pages, 3 figures, Proceeding of The Sixth European Conference on Neutron Scattering, Zaragoza Spain, August 30 to September 4 201

    OpenACC Based GPU Parallelization of Plane Sweep Algorithm for Geometric Intersection

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    Line segment intersection is one of the elementary operations in computational geometry. Complex problems in Geographic Information Systems (GIS) like finding map overlays or spatial joins using polygonal data require solving segment intersections. Plane sweep paradigm is used for finding geometric intersection in an efficient manner. However, it is difficult to parallelize due to its in-order processing of spatial events. We present a new fine-grained parallel algorithm for geometric intersection and its CPU and GPU implementation using OpenMP and OpenACC. To the best of our knowledge, this is the first work demonstrating an effective parallelization of plane sweep on GPUs. We chose compiler directive based approach for implementation because of its simplicity to parallelize sequential code. Using Nvidia Tesla P100 GPU, our implementation achieves around 40X speedup for line segment intersection problem on 40K and 80K data sets compared to sequential CGAL library

    Battery health determination by subspace parameter estimation and sliding mode control for an all-electric Personal Rapid Transit vehicle — the ULTra

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    The paper describes a real-time adaptive battery modelling methodology for use in an all electric personal rapid transit (PRT) vehicle. Through use of a sliding-mode observer and online subspace parameter estimation, the voltages associated with monitoring the state of charge (SoC) of the battery system are shown to be accurately estimated, even with erroneous initial conditions in both the model and parameters. In this way, problems such as self- discharge during storage of the cells and SoC drift (as usually incurred by coulomb-counting methods due to overcharging or ambient temperature fluctuations) are overcome. Moreover, through online monitoring of the degradation of the estimated parameters, battery ageing (State of Health) can be monitored and, in the case of safety- critical systems, cell failure may be predicted in time to avoid inconvenience to passenger networks. Due to the adaptive nature of the proposed methodology, this system can be implemented over a wide range of operating environments, applications and battery topologies, by adjustment of the underlying state-space model

    Policing the Police: Balancing the Right to Privacy Against the Beneficial Use of Drone Technology

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    The cost of buying, operating, and maintaining manned aircraft traditionally limited the government’s ability to conduct widespread aerial surveillance. But drone technology is eroding this natural limit because they are cheaper, stealthier, and can be used as a platform for other powerful surveillance tools. Drones are ideally suited for numerous law enforcement tasks such as search and rescue, crime scene investigations, and gaining a bird’s-eye view in dangerous active shooter or hostage situations. Privacy rights advocates fear that drone capabilities are bringing us closer to a “surveillance society” in which our every move is monitored, recorded, and scrutinized by the government, and have led the fight to either require police to obtain a warrant before using a drone or to ban the use of drones altogether. At the federal government level, only the FAA regulates drones but the Agency considers privacy outside the scope of its authority. Approximately one-third of states require law enforcement to obtain a warrant prior to using a drone to conduct a search or surveillance. A handful of local governments have banned the use of drones by law enforcement entirely in response to privacy concerns. However, overly broad restrictions on drone use have an unintended consequence in that they also curtail non-invasive, beneficial uses of drones. The Fourth Amendment likely does not protect individuals from warrantless drone surveillance provided the drone does not physically trespass and only captures what is visible from public airspace. This Note considers the twin harms of a surveillance society and depriving law enforcement of the beneficial uses of drones and concludes that states, as the laboratories of democracy, must act to reign in the use of unmanned aircraft by law enforcement so that public backlash against the threat to privacy does not result in the total deprivation of this useful technology
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