The influence of context on lifeline behavior: Local policies under wind storm and earthquake scenarios     

Dorothy Reed  Jane Preuss  Jaewook Park 《Natural Hazards》2006,39(2):289-307

Local policies can play an important role in establishing a context that shapes vulnerability and influences subsequent recovery of lifelines under the natural hazards of extreme wind and seismic events. External factors, such as access availability, have long been known to influence the rate of restoration of utility systems following blackouts. Thus, since system performance takes place within a socio-technical-political context, it can be anticipated that selected local policies may also influence either the geographic extent of damage or the rate of restoration or both. This project empirically validates the assumption that selected local non-design policies establish a context that significantly (measurably) influences system functionality in terms of spatial extent and duration of outage.  相似文献   

Determining meteoroid bulk densities using a plasma scattering model with high-power large-aperture radar data     

Sigrid Close  Ryan Volz  Rohan Loveland  Alex Macdonell  Patrick Colestock  Ivan Linscott  Meers Oppenheim 《Icarus》2012,221(1):300-309

We present an improved technique for calculating bulk densities of low-mass (<1 g) meteoroids using a scattering model applied to the high-density plasma formed around the meteoroid as it enters Earth’s atmosphere. These plasmas, referred to as head echoes, travel at or near the speed of the meteoroid, thereby allowing the determination of the ballistic coefficient (mass divided by physical cross-section), which depends upon speed and deceleration. Concurrently, we apply a scattering model to the returned signal strength of the head echo in order to correlate radar-cross-section (RCS) to plasma density and meteoroid mass. In this way, we can uniquely solve for the meteoroid mass, radius and bulk density independently. We have applied this new technique to head echo data collected in 2007 and 2008 simultaneously at VHF (160 MHz) and UHF (422 MHz) at ALTAIR, which is a high-power large-aperture radar located on the Kwajalein Atoll. These data include approximately 20,000 detections with dual-frequency, dual-polarization, and monopulse (i.e. angle) returns. From 2000 detections with the smallest monopulse errors, we find a mean meteoroid bulk density of 0.9 g/cm³ with observations spanning almost three orders of magnitude from 0.01 g/cm³ to 8 g/cm³. Our results show a clear dependence between meteoroid bulk density and altitude of head echo formation, as well as dependence between meteoroid bulk density and 3D speed. The highest bulk densities are detected at the lowest altitudes and lowest speeds. Additionally, we stipulate that the approximations used to derive the ballistic parameter, in addition to neglecting fragmentation, suggest that the traditional ballistic parameter must be used with caution when determining meteoroid parameters.  相似文献   

Inorganic carbon dynamics and CO<Subscript>2</Subscript> flux associated with coal-mine drainage sites in Blythedale PA and Lambert WV,USA     

Dorothy J. Vesper  Johnathan E. Moore  James P. Adams 《Environmental Earth Sciences》2016,75(4):340

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Attenuation and diel cycling of coal-mine drainage constituents in a passive treatment wetland: A case study from Lambert Run,West Virginia,USA     

Dorothy J. Vesper  Michael J. Smilley 《Applied Geochemistry》2010

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