8,501 research outputs found
Towards Space Solar Power - Examining Atmospheric Interactions of Power Beams with the HAARP Facility
In the most common space solar power (SSP) system architectures, solar energy
harvested by large satellites in geostationary orbit is transmitted to Earth
via microwave radiation. Currently, only limited information about the
interactions of microwave beams with energy densities of several tens to
hundreds of W/m with the different layers of the atmosphere is available.
Governmental bodies will likely require detailed investigations of safety and
atmospheric effects of microwave power beams before issuing launch licenses for
SSP satellite systems. This paper proposes to collect representative and
comprehensive data of the interaction of power beams with the atmosphere by
extending the infrastructure of the High Frequency Active Auroral Research
Program (HAARP) facility in Alaska, USA. Estimates of the transmission
infrastructure performance as well as measurement devices and scientific
capabilities of possible upgrade scenarios will be discussed. The proposed
upgrade of the HAARP facility is expected to deliver a wealth of data and
information which could serve as a decision base for governmental launch
licensing of SSP satellites, and which can be used in addition to deepen public
acceptance of SSP as a large-scale renewable energy source.
Copyright 2014 IEEE. Personal use of this material is permitted. Permission
from IEEE must be obtained for all other uses, in any current or future media,
including reprinting/republishing this material for advertising or promotional
purposes, creating new collective works, for resale or redistribution to
servers or lists, or reuse of any copyrighted component of this work in other
works.Comment: 7 pages, 3 figures; to be published in IEEE Xplore, in Proceedings to
IEEE Aerospace 2014 Conference, Mar 1 - 8, 2014, Big Sky, MT, US
Nonlinear mirror instability
Slow dynamical changes in magnetic-field strength and invariance of the
particles' magnetic moments generate ubiquitous pressure anisotropies in weakly
collisional, magnetized astrophysical plasmas. This renders them unstable to
fast, small-scale mirror and firehose instabilities, which are capable of
exerting feedback on the macroscale dynamics of the system. By way of a new
asymptotic theory of the early nonlinear evolution of the mirror instability in
a plasma subject to slow shearing or compression, we show that the instability
does not saturate quasilinearly at a steady, low-amplitude level. Instead, the
trapping of particles in small-scale mirrors leads to nonlinear secular growth
of magnetic perturbations, . Our theory explains
recent collisionless simulation results, provides a prediction of the mirror
evolution in weakly collisional plasmas and establishes a foundation for a
theory of nonlinear mirror dynamics with trapping, valid up to .Comment: 5 pages, submitte
LOW-MASS X-RAY BINARIES AND THEIR RELATION TO THE NON-X-RAY SOURCES
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73252/1/j.1749-6632.1977.tb37032.x.pd
X-ray Pulsations in the Supersoft X-ray Binary CAL 83
X-ray data reveal that the supersoft X-ray binary CAL 83 exhibits 38.4 minute
pulsations at some epochs. These X-ray variations are similar to those found in
some novae and are likely to be caused by nonradial pulsations the white dwarf.
This is the first detection of pulsations in a classical supersoft X-ray
binary.Comment: revised text; 11 pages and 3 figures; accepted for publication in the
Astronomical Journa
Introduction
This is the author accepted manuscript. The final version is available from Bristol Record Society via the DOI in this record Archived with permission of the Bristol Record SocietyBristol Record Society's publications vol. 6
Geospatial analysis of water and nutrient transport in two northern Colorado mixed-landuse watersheds
2011 Fall.Includes bibliographical references.This study examines the effect of different sources, transport pathways, and hydrologic regimes on phosphorus concentrations along a pristine-urban-agricultural gradient. A total of 48 sampling locations were monitored to characterize total phosphorus concentrations in the Cache la Poudre River Watershed in Northern Colorado. The comprehensive design of sampling locations aimed to capture the influence of anthropogenic activities and geospatial heterogeneity. Samples were collected at seven points in time with distinct climatic and hydrologic characteristics from April 2010 to February 2011. A geographic information system (GIS) was used to measure the overland, irrigation ditch, and stream/river distances from the sources to sampling locations. Analysis of variance, non-linear regression, and multiple linear regression models were used in combination to explore the co-variation of phosphorus concentrations with capacities of upstream WWTPs and CAFOs, along with other geospatial factors. It was evident, under all hydrologic conditions, that phosphorus concentrations downstream from WWTPs were significantly higher than the concentrations upstream of the facilities. Transport from WWTPs governed phosphorus concentrations in surface water during dry and low flow conditions, whereas contribution of CAFOs was significant during rainfall events. The total flow distance (a function of overland, irrigation ditch, and stream/river distances) from CAFOs to the sample locations was strongly associated with phosphorus concentrations during precipitation events. The results of this study provide the foundation for creating a decision support system for water quality analysis, monitoring, and management in the Poudre River basin and other similar mixed-land use watersheds. After examining the Poudre River watershed, a thorough investigation of Boxelder Creek basin was executed. The objectives were to gain an understanding of the geospatial heterogeneity and hydrologic complexity of the watershed using available data, aerial photography, and ground truthing and to develop a model that could accurately simulate the hydrology and nutrient routing in the watershed. Modeling the system using a simplified method for irrigation produced simulated results that were inconsistent with observed flow measurements. These results seem to indicate that irrigation ditches play a vital role in the hydrologic cycle of the basin. Previous studies indicate that watersheds in the study region can be accurately modeled; and although stream flow was not adequately simulated, the model did perform better when estimating total phosphorus concentrations. Therefore, future studies attempting to model basins containing irrigation ditches, like Boxelder Creek basin, should incorporate methods for representing the channels and their various interactions with the natural system. Routing irrigation canals through the watershed, along with irrigation and manure application methods described in this study, should improve the feasibility of modeling the heterogeneity of mixed landuse watersheds
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