Vehicle test report: South Coast technology electric conversion of a Volkswagen Rabbit

The South Coast Technology Volkswagen Rabbit, was tested at the Jet Propulsion Laboratory's (JPL) dynamometer facility and at JPL's Edwards Test Station (ETS). The tests were performed to characterize certain parameters of the South Coast Rabbit and to provide baseline data that will be used for the comparison of near term batteries that are to be incorporated into the vehicle. The vehicle tests were concentrated on the electrical drive system; i.e., the batteries, controller, and motor. The tests included coastdowns to characterize the road load, maximum effort acceleration, and range evaluation for both cyclic and constant speed conditions. A qualitative evaluation of the vehicle was made by comparing its constant speed range performance with those vehicles described in the document 'state of the Art assessment of Electric and Hybrid Vehicles'. The Rabbit performance was near to the best of the 1977 vehicles

Warp-speed adaptation to novel hosts after 300 generations of enforced dietary specialisation in the seed beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae)

Thank you to Paul Eady for providing C. maculatus to initiate our laboratory population and advice on rearing them. The study was funded by the University of Aberdeen core teaching funds (honours project budget to TP), and by a doctoral training grant to AL from the BBSRC-EastBio doctoral training partnershipPeer reviewedPublisher PD

High repetition rate sealed CO2 TEA lasers using heterogeneous catalysts

The significant operational advantages offered by CO2 lasers, operating in the 10.6 micron region of the spectrum, over current solid state lasers, emitting in the near IR region, have prompted increased interest in the development of compact, reliable, rugged CO2 laser sources. Perhaps the most critical aspect associated with achieving a laser compatible with military use is the development of lasers which require no gas replenishment. Sealed, single shot, CO2 TEA lasers have been available for a number of years. Stark et al were first to demonstrate reliable sealed operation in single shot CO2 TEA lasers in 1975 using gas catalysis. GEC Avionics reported the compact, environmentally qualified, MKIII CO2 TEA laser with a pulse life of greater than 10 to the 6th power pulses in 1980. A sealed laser lifetime of greater than 10 to the 6th power pulses is acceptable for single shot cases, such as direct detection rangefinders for tank laser sights. However, in many other applications, such as tracking of fast moving targets, it is essential that a repetition rate of typically 30Hz to 100Hz is employed. In such cases, a pulse lifetime of 10 to the 6th power pulses is no longer sufficient and a minimum pulse lifetime 10 to the 7th power pulses is essential to ensure a useful service life. In 1983 Stark el al described a sealed, 100Hz CO2 TEA laser, with a life of greater than 2.6 x 10 to the 6th power, which employed heterogeneous catalysis. Following this pioneering work, GEC Avionics has been engaged in the development of sealed high repetition rate lasers with a pulse lifetime of 20 million pulses

Late-Time Behavior of Stellar Collapse and Explosions: I. Linearized Perturbations

Problem with the figures should be corrected. Apparently a broken uuencoder was the cause.Comment: 16pp, RevTex, 6 figures (included), NSF-ITP-93-8

IRREVERSIBLE INVESTMENT DECISIONS IN PERENNIAL CROPS WITH YIELD AND PRICE UNCERTAINTY

Optimal entry and exit thresholds for Georgia commercial peach production are calculated when both price and yield follow a Brownian motion process. The thresholds are based on an irreversible sunk-cost investment model, where revenue from peach production is affected by the timing of when to enter production. Results indicate stability in Georgia peach production, with growers who are currently producing peaches remaining in production and potential peach growers delaying investment unless they have the ability of earning enhanced returns.Crop Production/Industries,

Smoothed particle magnetohydrodynamic simulations of protostellar outflows with misaligned magnetic field and rotation axes

We have developed a modified form of the equations of smoothed particle magnetohydrodynamics which are stable in the presence of very steep density gradients. Using this formalism, we have performed simulations of the collapse of magnetised molecular cloud cores to form protostars and drive outflows. Our stable formalism allows for smaller sink particles (< 5 AU) than used previously and the investigation of the effect of varying the angle, {\theta}, between the initial field axis and the rotation axis. The nature of the outflows depends strongly on this angle: jet-like outflows are not produced at all when {\theta} > 30{\deg}, and a collimated outflow is not sustained when {\theta} > 10{\deg}. No substantial outflows of any kind are produced when {\theta} > 60{\deg}. This may place constraints on the geometry of the magnetic field in molecular clouds where bipolar outflows are seen.Comment: Accepted for publication in MNRAS, 13 pages, 14 figures. Animations can be found at http://www.astro.ex.ac.uk/people/blewis/research/outflows_misaligned_fields.htm

Promoting reflection in asynchronous virtual learning spaces: tertiary distance tutors' conceptions

Increasingly, universities are embedding reflective activities into the curriculum. With the growth in online tertiary education, how effectively is reflection being promoted or used in online learning spaces? Based on the notion that teachers’ beliefs will influence their approaches to teaching, this research sought to understand how a group of distance tutors at the UK Open University conceptualised reflection. It was hoped that these findings would illuminate their approaches to promoting reflection as part of their online pedagogies. Phenomenographic analysis indicated that these tutors conceptualised reflection in four qualitatively different ways. Furthermore, the data suggested that these educators held a combination of two conceptions: one that understood the origin of being reflective and one that understood the purpose of reflection. Analysis of structural aspects of these conceptions offered insight into tutors’ own perspectives for what is needed to make online learning environments fertile territory for reflective learning

Sculplexity: Sculptures of Complexity using 3D printing

We show how to convert models of complex systems such as 2D cellular automata into a 3D printed object. Our method takes into account the limitations inherent to 3D printing processes and materials. Our approach automates the greater part of this task, bypassing the use of CAD software and the need for manual design. As a proof of concept, a physical object representing a modified forest fire model was successfully printed. Automated conversion methods similar to the ones developed here can be used to create objects for research, for demonstration and teaching, for outreach, or simply for aesthetic pleasure. As our outputs can be touched, they may be particularly useful for those with visual disabilities.Comment: Free access to article on European Physics Letter

Late time tails from momentarily stationary, compact initial data in Schwarzschild spacetimes

An L-pole perturbation in Schwarzschild spacetime generally falls off at late times t as t^{-2L-3}. It has recently been pointed out by Karkowski, Swierczynski and Malec, that for initial data that is of compact support, and is initially momentarily static, the late-time behavior is different, going as t^{-2L-4}. By considering the Laplace transforms of the fields, we show here why the momentarily stationary case is exceptional. We also explain, using a time-domain description, the special features of the time development in this exceptional case.Comment: 7 pages, 5 figure