36,669 research outputs found
Sharp nonexistence results for a linear elliptic inequality involving Hardy and Leray potentials
No full textWe deal with nonnegative distributional supersolutions for a class of linear elliptic equations involving inverse-square potentials and logarithmic weights. We prove sharp nonexistence results
The density, construction and drag coefficient of electrostatic volcanic ash aggregates.
No full textRecent laboratory experiments have demonstrated that electrostatic charges generated during the fragmentation of volcanic pumice cause rapid aggregation of the silicate particles produced. Here, we present measurements of the mass and component particle size distribution of individual, electrostatically bound aggregates produced during these experiments. Particles produced by fracturing pumice aggregated as they fell ∼1.5 m within an enclosed fall chamber. Aggregate mass measurements indicate aggregate densities of ∼200 kg m−3 or less. The component particle size analysis demonstrates exponential-type cumulative distributions which are dominated (on a volume basis) by particles ∼10–40 μm in diameter and contain few particles >70 μm. By representing these particles as disks of 5 μm thickness the calculated aggregate densities are in agreement with those derived from the aggregate mass measurements and indicate a relatively constant aggregate density with size (in contrast with previous results from fall velocities). Combining the density measurements with fall velocity data allows the drag coefficient of aggregates to be determined. Empirical equations developed to describe the particle size distribution within aggregates are used to derive relative aggregation coefficients for the electrostatic aggregation process. Our results can be used within numerical models of volcanic plumes in order to improve their representation of electrostatic aggregation processes
Recent Results From the EU POF-PLUS Project: Multi-Gigabit Transmission Over 1 mm Core Diameter Plastic Optical Fibers
No full textRecent activity to achieve multi-gigabit transmission over 1 mm core diameter graded-index and step-index plastic optical fibers for distances up to 50 meters is reported in this paper. By employing a simple intensity-modulated direct-detection system with pulse amplitude or digital multi-tone modulation techniques, low-cost transceivers and easy to install large-core POFs, it is demonstrated that multi-gigabit transmission up to 10 Gbit/s over 1-mm core diameter POF infrastructure is feasible. The results presented in this paper were obtained in the EU FP7 POF-PLUS project, which focused on applications in different scenarios, such as in next-generation in-building residential networks and in datacom applications
Unshielded precipitation gauge collection efficiency with wind speed and hydrometeor fall velocity
No full textCollection efficiency transfer functions that compensate for wind-induced collection loss are presented and evaluated for unshielded precipitation gauges. Three novel transfer functions with wind speed and precipitation fall velocity dependence are developed, including a function from computational fluid dynamics modelling (CFD), an experimental fall velocity threshold function (HE1), and an experimental linear fall velocity dependence function (HE2). These functions are evaluated alongside universal (KUniversal) and climate-specific (KCARE) transfer functions with wind speed and temperature dependence. Transfer function performance is assessed using 30-minute precipitation event accumulations reported by unshielded and shielded Geonor T-200B3 precipitation gauges over two winter seasons. The latter gauge was installed in a Double Fence Automated Reference (DFAR) configuration. Estimates of fall velocity were provided by a Precipitation Occurrence Sensor System (POSS). The CFD function reduced the RMSE (0.08 mm) relative to KUniversal (0.20 mm), KCARE (0.13 mm), and the unadjusted measurements (0.24 mm), with a bias error of 0.011 mm. The HE1 function provided a RMSE of 0.09 mm and bias error of 0.006 mm, capturing well the collection efficiency trends for rain and snow. The HE2 function better captured the overall collection efficiency, including mixed precipitation, resulting in a RMSE of 0.07 mm and bias error of 0.006 mm. These functions are assessed across solid and liquid hydrometeor types and for temperatures between -22 °C and 19 °C. The results demonstrate that transfer functions incorporating hydrometeor fall velocity can dramatically reduce the uncertainty of adjusted precipitation measurements relative to functions based on temperature
Building at Horse Sanctuary, Fall River County
No full text35 mm slide, small building covered in different colored tar paperDrawer info: Custer- Fall River; Fall River CountyKodachrome Film Horse Sanct. Fall River Co 3 Dec 97N1
Cabin at Horse Sanctuary, Fall River County
No full text35 mm slide, cabin with a covered front porch and a metal roof surrounded by barbed wire fenceDrawer info: Custer- Fall River; Fall River CountyKodachrome Film Horse Sanct Fall River Co 6 Dec 97N1
Reservoir, Edgemont SD, Fall River County
No full text35 mm slide, field of grass with water in the backgroundDrawer info: Fall River - Hand; Edgemont Fall River Co2 D-1 TVA - Edgemont SD Reservoi
Reservoir, Edgemont SD, Fall River County
No full text35 mm slide, field of grass with water in the backgroundDrawer info: Fall River - Hand; Edgemont Fall River CoD-7 TVA - Edgemont SD Reservoi
Employing M1 direct calibration/de-embedding approaches for large signal model validation at mm-wave frequencies
No full textIn this contribution, we employ direct calibration/de-embedding approaches to validate the large signal device model of state-of-the-art HBTs and CMOS technologies operating in the mm-wave frequency band WR6. The capability of placing the first tier calibration reference plane in close proximity to the DUT allows the large signal metric to be directly compared with foundry models.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic
Buildings, Hot Springs SD, Fall River County
No full text35 mm slide, back view of a row of buildings with some vehicles parked next to themDrawer info: Fall River - Hand; Bodega Building Hot Springs Fall River CountyEktachrome Film Bodega Building Hot Springs Fall River Co. 7 96D0
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