A ground track control algorithm for the Topographic Mapping Laser Altimeter (TMLA)

The results of an analysis of an algorithm that will provide autonomous onboard orbit control using orbits determined with Global Positioning System (GPS) data. The algorithm uses the GPS data to (1) compute the ground track error relative to a fixed longitude grid, and (2) determine the altitude adjustment required to correct the longitude error. A program was written on a personal computer (PC) to test the concept for numerous altitudes and values of solar flux using a simplified orbit model including only the J sub 2 zonal harmonic and simple orbit decay computations. The algorithm was then implemented in a precision orbit propagation program having a full range of perturbations. The analysis showed that, even with all perturbations (including actual time histories of solar flux variation), the algorithm could effectively control the spacecraft ground track and yield more than 99 percent Earth coverage in the time required to complete one coverage cycle on the fixed grid (220 to 230 days depending on altitude and overlap allowance)

Campus Environment 2008: A National Report Card on Sustainability in Higher Education

Presents survey findings on national and regional trends among colleges in environmental leadership in management, academic courses in sustainability, and conservation efforts in operations. Profiles exemplary programs and notes areas for improvement

Correlations of the IR Luminosity and Eddington Ratio with a Hard X-ray Selected Sample of AGN

We use the SWIFT Burst Alert Telescope (BAT) sample of hard x-ray selected active galactic nuclei (AGN) with a median redshift of 0.03 and the 2MASS J and K band photometry to examine the correlation of hard x-ray emission to Eddington ratio as well as the relationship of the J and K band nuclear luminosity to the hard x-ray luminosity. The BAT sample is almost unbiased by the effects of obscuration and thus offers the first large unbiased sample for the examination of correlations between different wavelength bands. We find that the near-IR nuclear J and K band luminosity is related to the BAT (14 - 195 keV) luminosity over a factor of $10^3$ in luminosity ($L_{IR} \approx L_{BAT}^{1.25}$)and thus is unlikely to be due to dust. We also find that the Eddington ratio is proportional to the x-ray luminosity. This new result should be a strong constraint on models of the formation of the broad band continuum.Comment: accepted to ApJ

Renewable power options enabled by Local Electricity Trading.

The paper is prepared as part of an Australian Renewable Energy Agency (ARENA) funded research project led by the Institute for Sustainable Futures (ISF) at the University of Technology Sydney (UTS), Facilitating Local Network Charges and Virtual Net Metering and a project funded by the Victorian Government Department of Environment, Land, Water and Planning (DELWP), Virtual Renewable Power Stations. A key task in the ISF project is to run five virtual trials of Local Electricity Trading (LET)1 and local network charges, one of which will take place in the Moira Shire and Swan Hill Rural City Council areas in regional Victoria. The Moira and Swan Hill trial will examine either the business model for a one-to-many (Community Power Station) or for a many-to-one (also called a Virtual Power Station, or VPS). Both of these models are likely to be enabled if Local Electricity Trading becomes commonly available. The primary interest of the Councils is to improve the resilience of the local economy by retaining energy spending within the area, to increase the capacity of local renewable energy generation and to enable local residents and businesses to participate in the renewable energy generation. The purpose of this paper is to assist the Councils to choose which model to take forward into a trial

Local Network Charges and Local Electricity Trading: Market Scan

This report provides an overview of current literature and information relating to local network charges, local electricity trading (also called virtual net metering or VNM), and virtual power stations. The focus is information particularly relevant to Australia, as well as global precedents in each area

Comparison of H alpha synoptic charts with the large-scale solar magnetic field as observed at Stanford

Two methods of observing the neutral line of the large-scale photospheric magnetic field are compared: (1) neutral line positions inferred from H alpha photographs and (2) observations of the photospheric magnetic field made with low spatial resolution (3 arc min.) and high sensitivity using the Stanford magnetograph. The comparison is found to be very favorable

Multi-site mean-field theory for cold bosonic atoms in optical lattices

We present a detailed derivation of a multi-site mean-field theory (MSMFT) used to describe the Mott-insulator to superfluid transition of bosonic atoms in optical lattices. The approach is based on partitioning the lattice into small clusters which are decoupled by means of a mean field approximation. This approximation invokes local superfluid order parameters defined for each of the boundary sites of the cluster. The resulting MSMFT grand potential has a non-trivial topology as a function of the various order parameters. An understanding of this topology provides two different criteria for the determination of the Mott insulator superfluid phase boundaries. We apply this formalism to $d$-dimensional hypercubic lattices in one, two and three dimensions, and demonstrate the improvement in the estimation of the phase boundaries when MSMFT is utilized for increasingly larger clusters, with the best quantitative agreement found for $d=3$. The MSMFT is then used to examine a linear dimer chain in which the on-site energies within the dimer have an energy separation of $\Delta$. This system has a complicated phase diagram within the parameter space of the model, with many distinct Mott phases separated by superfluid regions.Comment: 30 pages, 23 figures, accepted for publication in Phys. Rev.