The construction of saturated 2Rk-p designs

Combinatorial and sequential analyses for optimization of saturated design

A Shotgun Model for Gamma Ray Bursts

We propose that gamma ray bursts (GRBs) are produced by a shower of heavy blobs running into circumstellar material at highly relativistic speeds. The gamma ray emission is produced in the shocks these bullets drive into the surrounding medium. The short term variability seen in GRBs is set by the slowing-down time of the bullets while the overall duration of the burst is set by the lifetime of the central engine. A requirement of this model is that the ambient medium be dense, consistent with a strong stellar wind. The efficiency of the burst can be relatively high.Comment: 4 pages, 2 figures, revised version accepted by ApJ Letter

Lunar soil properties and soil mechanics

The long-range objectives were to develop methods of experimentation and analysis for the determination of the physical properties and engineering behavior of lunar surface materials under in situ environmental conditions. Data for this purpose were obtained from on-site manned investigations, orbiting and softlanded spacecraft, and terrestrial simulation studies. Knowledge of lunar surface material properties are reported for the development of models for several types of lunar studies and for the investigation of lunar processes. The results have direct engineering application for manned missions to the moon

Search for Stable Magnetohydrodynamic Equilibria in Barotropic Stars

It is now believed that magnetohydrodynamic equilibria can exist in stably stratified stars due to the seminal works of Braithwaite & Spruit (2004) and Braithwaite & Nordlund (2006). What is still not known is whether magnetohydrodynamic equilibria can exist in a barotropic star, in which stable stratification is not present. It has been conjectured by Reisenegger (2009) that there will likely not exist any magnetohydrodynamical equilibria in barotropic stars. We aim to test this claim by presenting preliminary MHD simulations of barotropic stars using the three dimensional stagger code of Nordlund & Galsgaard (1995).Comment: 4 pages, 2 figures, to appear in the proceedings of IAUS 302: "Magnetic Fields Throughout Stellar Evolution

Dead in the water: an analysis of industry practices and perceptions on vessel efficiency and stranded ship assets

This paper presents an analysis of the concept of stranded assets in the context of shipping. It presents the findings of a series of semi-structured interviews with the industry’s leading debt and equity financiers as well as a variety of financial intermediaries on the topics of energy efficiency, efficiency retrofits and stranded assets. The results show differentiation amongst financial actors and by entities that finance assets and those that finance balance sheets. Amongst debt players that finance assets, competitive advantage is a consistent rationale for the use of vessel efficiency information. Actors that view vessel efficiency as a competitive advantage typically either finance efficiency retrofits or have considered doing so. There is mixed awareness of stranded assets and perceptions of the risks they pose to vessel financiers. The case for the inclusion of vessel efficiency. information in vessel financing decisions is building, yet further work is needed. While some financial actors connect efficiency-derived competitive advantage to financial risk mitigation, there is a strong case for broader consideration in the context of market cyclicality and the associated increase in probability of vessel stranding. Such considerations may also have a positive impact on operational cashflow and thus investment returns. This research concludes that, should this link be analogous to other industries, vessel efficiency may be a good determinant of the vulnerability of portfolios to climate constraints on the industry that force the stranding of some assets