Exploring Mobility Indoors: an Application of Sensor‐based and GIS Systems

The popularization of tracking devices, such as GPS, accelerometers and smartphones, have made it possible to detect, record, and analyze new patterns of human movement and behavior. However, employing GPS alone for indoor localization is not always possible due to the system's inability to determine location inside buildings or in places of signal occlusion. In this context, the application of local wireless networks for determining position is a promising alternative solution, although they still suffer from a number of limitations due to energy and IT‐resources. Our research outlines the potential for employing indoor wireless network positioning and sensor‐based systems to improve the collection of tracking data indoors. By applying various methods of GIScience we developed a methodology that can be applicable for diverse human indoor mobility analysis. To show the advantage of the proposed method, we present the result of an experiment that included mobility analysis of 37 participants. We tracked their movements on a university campus over the course of 41 days and demonstrated that their movement behavior can be successfully studied with our proposed method.     

Peak atmospheric entry temperatures of micrometeorites

Abstract— We present numerical calculations of the peak temperatures experienced by micrometeorites during atmospheric entry. Results are given for particle diameters between 2 and 50 μm and for entry velocities between 10 and 25 km/s. A material density of 2 g/cm³ and an entry angle of 45° are used for the calculation, but the results presented here can be easily reinterpreted for other densities and for vertical entry.     

Particle aggregation in microgravity: Informal experiments on the International Space Station

We conducted experiments in space to investigate the aggregation of millimeter‐ and submillimeter‐sized particles in microgravity, an important early step in planet formation. Particulate materials included salt (NaCl), sugar (sucrose), coffee, mica, ice, Bjurböle chondrules, ordinary and carbonaceous chondrite meteorite fragments, and acrylic and glass beads, all triply confined in clear plastic containers. Angular submillimeter particles rapidly and spontaneously formed clusters strong enough to survive turbulence in a protoplanetary nebula. Smaller particles generally aggregated more strongly and quickly than larger ones. We observed only a weak dependence of aggregation time on particle number density. We observed no strong dependence on composition. Round, smooth particles aggregated weakly or not at all. In a mixture of particle types, some phases aggregated more readily than others, creating selection effects that controlled the composition of the growing clumps. The physical process of aggregation appears to be electrostatic in nature.     

The relationship between the magnetic properties of terrestrial igneous rocks and the composition and internal structure of their component Fe-oxide grains

Summary. Hysteresis loops and the demagnetization of saturation remanence (SIRM), before and after heating, are used to determine the high field magnetic behaviour and the coercivity spectra for common igneous rock types containing discrete types of magnetic carriers. These incude homogeneous to highly exsolved titanomagnetite grains, oxidized titanomagnetite grains (martite), exsolved hemo-ilmenite grains, and oxidized ilmenite grains. Specific internal structures and changes in composition due to oxidation are found to have characteristic effects on both high and low field magnetic properties.     

Short duration solar microwave bursts and associated soft X-ray emission

During the time period of November 1968 to March 1970, 259 15.4 GHz impulsive microwave bursts have been identified of which 147 had associated 2–12 Å soft X-ray bursts. Average durations, rise times, and decay times for the microwave bursts are 2.9 ± 2.4 min, 0.9 ± 0.8 min, and 2.2 ± 2.1 min, respectively.Total durations and decay times for the X-ray events display a wide range of values from a few minutes to several hours. Rise times for 50 % of the events fell in the range of 2 to 7 min. A significant fraction (32 %) of the X-ray events may exhibit a flux enhancement prior to the main outburst.For 85 % of the flare cases, the X-ray event begins simultaneously with or before the microwave event. In 91 % of the cases the X-ray event peaks later than the microwave event. The average delay is 3.0 ± 1.9 min with 50 % of cases in the range of 0 to 4 min.The X-ray flux increases are significantly correlated with the microwave flux, increases, having a correlation coefficient of 0.43 (> 99.9 % confident).This work was supported in part by the Office of Naval Research under contract NOOO14-68-A-0196-0009 and the National Aeronautics and Space Administration through grant NGL-16-001-002.     

Interplanetary dust particles near Jupiter

We calculate the expected counting rate of a flat micrometeoroid detector of finite sensitivity passing in hyperbolic orbit near a planet. We assume that the distribution of particle sizes, s, can be expressed as a power law spectrum of index p, i.e. dN(s) = Cs^?pds, and also that the particles encounter the sphere of influence of the planet with a certain speed v_∞. The results of the calculations are then compared with the results returned by Pioneer 10 in its flyby of Jupiter. The observed increase in impact rate near Jupiter can be completely explained in terms of gravitational “focusing” of particles which are in heliocentric orbits; i.e., they are not in orbit about Jupiter. The absolute concentration of particles near the orbit of Jupiter is of the same order as at 1 AU: the exact ratio being a function of particle speed and spectral index. Data from one flyby are insufficient to determine a unique value for both the spectral index, p, and the particle velocity, v_∞, but limits can be set. For reasonable encounter speeds (corresponding to eccentricities and inclinations of dust particles experienced near the Earth), the particles near Jupiter are characterized by a spectrum of index p ～ 3. The spectral index which best fits the data increases with increasing encounter speeds.     

RESIDENTIAL PREFERENCE PATTERNS OF AFRO-AMERICAN COLLEGE STUDENTS IN THREE DIFFERENT STATES

The residential preferences of Afro-American students in three black colleges in Pennsylvania, North Carolina, and Texas are factor analyzed to determine whether major differences exist. Mapping the factor scores for the students in each college reveals that state rankings vary markedly from one region to another, black spatial preferences differ markedly from those students attending predominately white universities, and preference patterns reflect contemporary interregional black migration trends.