3,941 research outputs found
Electricity Intensities of the OECD and South Africa: A Comparison
Improving a country’s electricity efficiency is considered one of the important ways to reduce its greenhouse gas emissions and to meet its commitments concerning climate change mitigation. In this paper, we conduct a comparative analysis between South Africa and OECD members’ total and sectoral electricity intensities. This is done to establish a sense of South Africa’s relative performance in this regard, to ascertain the possible scope for improvement and, if such scope exists, to determine in which of the industrial sectors
South Africa’s Electricity Consumption: A Sectoral Decomposition Analysis
South Africa's electricity consumption has increased sharply since the early 1990s. Here we conduct a sectoral decomposition analysis of the electricity consumption for the period 1993 to 2006, to determine the main drivers of this increase. The results show that the increase was due mainly to output- or production-related factors, with structural changes playing a secondary role. While there is some evidence of efficiency improvements, indicated here as a slowdown in the rate of increase in electricity intensity, it was not nearly sufficient to offset the combined production and structural effects that propelled electricity consumption higher.
Minimum fuel control of a pitch motion of a satellite in circular orbit
Time function analysis for optimal control of satellite attitude and control jet fuel consumption in circular orbit
Minimum time control of a nonlinear system
Time-optimal control problem studied for system representing second-order nonlinear differential equatio
Asymmetry measures for QSOs and companions
An asymmetry index is derived from ellipse-fitting to galaxy images, that
gives weight to faint outer features and is not strongly redshift-dependent.
These measures are made on a sample of 13 2MASS QSOs and their neighbour
galaxies, and a control sample of field galaxies from the same wide-field
imaging data. The QSO host galaxy asymmetries correlate well with visual tidal
interaction indices previously published. The companion galaxies have somewhat
higher asymmetry than the control galaxy sample, and their asymmetry is
inversely correlated with distance from the QSO. The distribution of
QSO-companion asymmetry indices is different from that for matched control
field galaxies at the significance level. We present the data and
discuss this evidence for tidal and other disturbances in the vicinity of QSOs.Comment: 13 pages, 2 tables, 4 figures; to appear in A
Fine-Structure FeII* Emission and Resonant MgII Emission in z = 1 Star-Forming Galaxies
We present a study of the prevalence, strength, and kinematics of ultraviolet
FeII and MgII emission lines in 212 star-forming galaxies at z = 1 selected
from the DEEP2 survey. We find FeII* emission in composite spectra assembled on
the basis of different galaxy properties, indicating that FeII* emission is
prevalent at z = 1. In these composites, FeII* emission is observed at roughly
the systemic velocity. At z = 1, we find that the strength of FeII* emission is
most strongly modulated by dust attenuation, and is additionally correlated
with redshift, star-formation rate, and [OII] equivalent width, such that
systems at higher redshifts with lower dust levels, lower star-formation rates,
and larger [OII] equivalent widths show stronger FeII* emission. We detect MgII
emission in at least 15% of the individual spectra and we find that objects
showing stronger MgII emission have higher specific star-formation rates,
smaller [OII] linewidths, larger [OII] equivalent widths, lower dust
attenuations, and lower stellar masses than the sample as a whole. MgII
emission strength exhibits the strongest correlation with specific
star-formation rate, although we find evidence that dust attenuation and
stellar mass also play roles in the regulation of MgII emission. Future
integral field unit observations of the spatial extent of FeII* and MgII
emission in galaxies with high specific star-formation rates, low dust
attenuations, and low stellar masses will be important for probing the
morphology of circumgalactic gas.Comment: 29 pages, 22 figures, 2 tables; accepted to Ap
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