73 research outputs found
Oxygen Ion Energization Observed At High Altitudes
We present a case study of significant heating (up to 8 keV) perpendicular to
the geomagnetic field of outflowing oxygen ions at high altitude (12 RE)
above the polar cap. The shape of the distribution functions indicates that
most of the heating occurs locally (within 0.2–0.4 RE in altitude). This
is a clear example of local ion energization at much higher altitude than
usually reported. In contrast to many events at lower altitudes, it is not
likely that the locally observed wave fields can cause the observed ion
energization. Also, it is not likely that the ions have drifted from some
nearby energization region to the point of observation. This suggests that
additional fundamentally different ion energization mechanisms are present at
high altitudes. One possibility is that the magnetic moment of the ions is
not conserved, resulting in slower outflow velocities and longer time for ion
energization
Oxygen ion energization by waves in the high altitude cusp and mantle
We present a comparative study of low frequency electric field spectral
densities and temperatures observed by the Cluster spacecraft in the high
altitude cusp/mantle region. We compare the relation between the O+
temperature and wave intensity at the oxygen gyrofrequency at each
measurement point and find a clear correlation. The trend of the correlation
agrees with the predictions by both an asymptotic mean-particle theory and a
test-particle approach. The perpendicular to parallel temperature ratio is
also consistent with the predictions of the asymptotic mean-particle theory.
At times the perpendicular temperature is significantly higher than predicted
by the models. A simple study of the evolution of the particle distributions
(conics) at these altitudes indicates that enhanced perpendicular
temperatures would be observed over many RE after heating ceases.
Therefore, sporadic intense heating is the likely explanation for cases with
high temperature and comparably low wave activity. We observe waves of
sufficient amplitude to explain the highest observed temperatures, while the
theory in general overestimates the temperature associated with the highest
observed wave activity, indicating that such high wave activity is very
sporadic
The Free State Public Transportation System: A Comparison Between Buses and Taxi Services and Adaptation of ICT Solutions
Conference ProceedingsThis paper explores Information Communication Technologies
(ICT) for consideration in the public transportation system in the Free State and
how the two main types of public transportation; buses and taxis, are likely to
adapt to these technologies. Taxis and buses operation and management of
operations are completely different; their differences are likely to affect how
each adapts to these technologies. Adaptation to the integrated public transportation
system by the bus and taxi users, drivers, and operators will be key to
successful ICT integration. Focusing on the benefits that ICT solutions have
brought in some regions in the world should not overshadow consideration for
possible slow adaptation, lack of acceptance or resistance by stakeholders when
applied in a different environment and a different public transportation system.
This paper considers the different operational scenarios, government
involvement and political will, public – driver – operator participation and
willingness and ICT awareness. Whether the technologies and applications will
be suitable and adaptable to the existing system and their perceived influence on
adaptation to an ICT integrated public transportation system from implementation
until there are fully embedded into the system are also considered. Feasibility
of some ICT solutions, to the decision makers and operators, considering
financial, technical and management feasibility and degree of integration will
influence the adaptation process
Treatment of landfill leachate by constructed wetlands
The performance of three constructed wetlands systems treating landfill leachate is described. Two are located in northern Poland (Szadolki near Gdansk and Gatka near Miastko) and one in southern Sweden (Örebro). The constructed wetlands in Szadolki consists of two parallel silty soil beds planted with reed with sub-surface horizontal flow of sewage. The constructed wetland in Gatka is a willow plantation on sandy soil, receiving leachate after preliminary sedimentation in a retention pond. The system in Örebro consists of a series of ponds with a surface flow of leachate, preceded by pre-treatment in an aerated tank with nitrogen stripping. The best treatment efficiencies were observed at Örebro. At the sub-surface flow wetlands in Szadolki and Gatka clogging problems occurred due to the unsatisfactory pre-treatment and low soil hydraulic conductivity resulting in lower treatment efficiencies
Localized practices and globalized futures: challenges for Alaska coastal community youth
An article from Maritime Studies (2015) 14:
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