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 $\sim95$ 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