Remote sensing of lunar aureole with a sky camera: Adding information in the nocturnal retrieval of aerosol properties with GRASP code

The use of sky cameras for nocturnal aerosol characterization is discussed in this study. Two sky cameras are configured to take High Dynamic Range (HDR) images at Granada and Valladolid (Spain). Some properties of the cameras, like effective wavelengths, sky coordinates of each pixel and pixel sensitivity, are characterized. After that, normalized camera radiances at lunar almucantar points (up to 20° in azimuth from the Moon) are obtained at three effective wavelengths from the HDR images. These normalized radiances are compared in different case studies to simulations fed with AERONET aerosol information, giving satisfactory results. The obtained uncertainty of normalized camera radiances is around 10% at 533 nm and 608 nm and 14% for 469 nm. Normalized camera radiances and six spectral aerosol optical depth values (obtained from lunar photometry) are used as input in GRASP code (Generalized Retrieval of Aerosol and Surface Properties) to retrieve aerosol properties for a dust episode over Valladolid. The retrieved aerosol properties (refractive indices, fraction of spherical particles and size distribution parameters) are in agreement with the nearest diurnal AERONET products. The calculated GRASP retrieval at night time shows an increase in coarse mode concentration along the night, while fine mode properties remained constant.This work was supported by the Andalusia Regional Government (project P12-RNM-2409) and by the “Consejería de Educación, Junta de Castilla y León” (project VA100U14).Spanish Ministry of Economy and Competitiveness and FEDER funds under the projects CGL2013-45410-R, CMT2015-66742-R, CGL2016-81092-R.“Juan de la Cierva-Formación” program (FJCI-2014-22052).European Union's Horizon 2020 research and innovation programme through project ACTRIS-2 (grant agreement No 654109)

Resources for sports engineering education

This paper serves as a resource guide for Sports Engineering educators. The paper covers key topics in Sports Engineering, including ball impact, friction, safety and materials. A variety of resource types are presented to reflect modern methods of learning and searching for information, including textbooks, research and review papers, websites and videos. The field could benefit from more resources specifically designated for teaching Sports Engineering, particularly textbooks

Using a Local Positioning System to Track 2D Motion

Tracking the motion of an object in 2D as a demonstration in a physics classroom or as a laboratory activity is difficult to accomplish in real time with traditional equipment used by educators. A local positioning system (LPS), like the Pozyx Creator series LPS,1 has a potentially wide range of educational applications for introductory physics courses. In a previous article2 we reported using this product to track one-dimensional motion, pressure, rotation, and magnetic field data, but here we discuss how such systems can provide location information (to within approximately ±10 cm) in one, two, and potentially three dimensions both indoors and outdoors

Comparative Modeling of Free Fall and Drag-Enhanced Motion in the Classical Physics Drop Experiment

A new series of introductory physics experiments for teaching the kinematics and dynamics of falling bodies is presented. These learning activities are enabled by newly available position-tracking technology that allows for the direct acquisition of coordinate data from moving objects. Students are led through an iterative inquiry process that explores both free fall and drag-enhanced physical models, for different velocity regimes, emphasizing a comparative modeling approach to science. Learners discover how the experimental design, including the properties of the dropped objects, the dropping distance, and the uncertainty of the measuring device, impacts the ability to explore the validity of physical models with or without drag

Data From: Comparative Modeling of Free Fall and Drag-Enhanced Motion in the Classical Physics Drop Experiment

A new series of introductory physics experiments for teaching the kinematics and dynamics of falling bodies is presented. These learning activities are enabled by newly available position-tracking technology that allows for the direct acquisition of coordinate data from moving objects. Students are led through an iterative inquiry process that explores both free fall and drag- enhanced physical models, for different velocity regimes, emphasizing a comparative modeling approach to science. Learners discover how the experimental design, including the properties of the dropped objects, the dropping distance, and the uncertainty of the measuring device, impacts the ability to explore the validity of physical models with or without drag

Opportunities in Physics Education: Low-Cost Position Tracking for Use in Kinematics Labs

Traditional introductory physics kinematics laboratories utilized a few different instruments for locating objects in motion, all of which have shortcomings. Some provide only timing data, which heavily restricts trajectories and data collection. Some instruments provide more measurements but restrict object shapes, orientations, and textures. Still others require extensive pre-processing. None of these traditional instruments provide two- or three-dimensional position data. New, low-cost, local positioning technology, based on radio frequency wireless communications, is available that enables novel redesigns of physics laboratories. This technology provides two- and three-dimensional position measurements, continuously, at data rates of 10 Hz or faster, from any object to which it can be affixed. Our research group at Portland State University is exploring how this technology can be applied to reconstruct and improve introductory laboratories, making them easier to perform while increasing the amount of usable data gathered. Additionally, we seek to enhance model-based learning experience in labs by confronting students with more diverse models than traditionally encountered. For example, we are pursuing applications in free-fall experiments, aerodynamic friction, two-dimensional motion, two-dimensional collisions, tug-of-war competitions, as well as Astronomy applications such as retrograde motion

Infrared response of charge-coupled devices

With a band gap of silicon of 1.1eV, the largest wavelength that can excite electrons from the valence to the conduction band is roughly 1100nm. As a consequence, in, for instance, a charge-coupled device, the quantum efficiency (QE) for wavelengths larger than 1100nm is assumed to be zero. We found that there is a response at those longer wavelengths and that the response decreases with increasing wavelength. The QE increases with increasing chip temperature which suggests a thermally activated process. Impurities in the silicon provide the energy levels in the band gap, from which electrons can be excited either thermally or by absorption of a photon. It is these impurities that contribute to the infrared response. We characterized the response at chip temperatures of 248 K to 293 K for wavelengths from 1200 nm to 1600 nm and calculated the activation energies at these wavelengths. We found that hot pixels, i.e., pixels with extraordinary high counts in a dark frame, tend to respond stronger to infrared light than normal pixels. This correlation gets stronger for longer wavelengths. It is argued that this response can be used for probing the impurities present in the silicon bulk of the sensors.Department of MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc