Coins falling in water

When a coin falls in water, its trajectory is one of four types determined by its dimensionless moment of inertia $I^\ast$ and Reynolds number Re: (A) steady; (B) fluttering; (C) chaotic; or (D) tumbling. The dynamics induced by the interaction of the water with the surface of the coin, however, makes the exact landing site difficult to predict a priori. Here, we describe a carefully designed experiment in which a coin is dropped repeatedly in water, so that we can determine the probability density functions (pdf) associated with the landing positions for each of the four trajectory types, all of which are radially symmetric about the center-drop line. In the case of the steady mode, the pdf is approximately Gaussian distributed, with variances that are small, indicating that the coin is most likely to land at the center, right below the point it is dropped from. For the other falling modes, the center is one of the least likely landing sites. Indeed, the pdf's of the fluttering, chaotic and tumbling modes are characterized by a "dip" around the center. For the tumbling mode, the pdf is a ring configuration about the center-line, with a ring width that depends on the dimensionless parameters $I^\ast$ and Re and height from which the coin is dropped. For the chaotic mode, the pdf is generally a broadband distribution spread out radially symmetrically about the center-line. For the steady and fluttering modes, the coin never flips, so the coin lands with the same side up as was dropped. For the chaotic mode, the probability of heads or tails is close to 0.5. In the case of the tumbling mode, the probability of heads or tails based on the height of the drop which determines whether the coin flips an even or odd number of times during descent

Development of an improved mirror facet for space applications

A fabrication technique was successfully developed for a metallic aluminum honeycomb, high-accuracy, lightweight, and long-life solar concentrator (mirror) for Advanced Solar Dynamic Space Power Systems. The program scope was limited to the development, fabrication, evaluation, and delivery of a solar concentrator facet (petal) that was sized for a 2-meter deployable solar concentrator. A surface accuracy of 1.0 mrad was achieved. The development incorporated tooling design, material selection, facet forming, adhesive selection, testing, and analysis. Techniques for applying levelizing, reflective, and protective optical coatings were also developed

Emissions Trading and the Convergence of the Australian Electricity and Transport Markets

Bottom up partial equilibrium modelling of the energy sector has tended to focus on the electricity sector given its typically large share of total emissions, the deregulation of that market in many countries and the relatively well understood technology options. In contrast, this paper employs a model of the energy sector to investigate the proportion electricity and transport may contribute given the relative cost of abatement in those sectors, for specified emission targets. A related issue is the potential convergence of the two sectors through greater uptake of electrically powered transport.Energy, Emissions trading, Electricity and transport, integrated modelling, Environmental Economics and Policy, Public Economics,

Theoretical investigation of the scope of sequential ligand tuning using a bifunctional scorpionate tris(1,2,4-triazolyl)borate-based architecture

The donor properties of a series of tripodal mixed N-donor/carbene ligands derived through sequential alkylation of hydrotris(1,2,4-triazolyl)borate have been investigated by density functional theory (DFT) methods. The structures of complexes of the form [Mo(L)(CO)3]- were optimized (L = [HB(1,2,4-triazolyl)n(1,2,4-triazol-5-ylidene)3-n]- (n = 0 – 3), hydrotris(pyrazolyl)borate, hydrotris(3,5-dimethylpyrazolyl)borate and hydrotris(imidazol-2-ylidene)borate) and nuCO frequencies for these complexes and partial charges of their Mo(CO)3 fragments were determined. Results show that ligand donation is highly tunable when compared to similar experimentally known ligands with a shift in the symmetric nuCO stretching mode of -39 cm -1 on going from the tris(1,2,4-triazolyl)borate complexes to that of the triscarbene hydrotris(1,2,4-triazol-5-ylidene) and an increase in partial charge (distributed multipole analysis) of the Mo(CO)3 fragment from -0.23 to -0.48

Taxonomic assessment of two pygopodoid gecko subspecies from Western Australia

Abstract Subspecies designations for herpetofauna in Western Australia were largely coined in the 20th century where rigorous evolutionary concepts to species were not consistently applied. Rather, subspecies tended to designate geographic populations of similar-looking taxa to nominate forms, usually differing in size, pattern or colour and, at best, a few scalation differences. Here we re-evaluate two pygopodoid taxa from Western Australia using a combination of published and original genetic data coupled with a reassessment of morphology. We review these differences in light of an integrative taxonomic approach that looks to find multiple independent lines of evidence to establish the evolutionary independence of populations. For the pygopod species Pletholax gracilis, we found consistent diagnostic characters (e.g. body size, visibility of ear opening, scalation) and a deep genetic divergence between the two subspecies. We therefore raise each subspecies to full species: P. gracilis and P. edelensis. The two subspecies of the carphodactylid gecko Nephrurus wheeleri were also assessed, and we found strong genetic and morphological evidence (e.g. body size, scalation, pattern) to raise these to full species: N. wheeleri and N. cinctus. By revisiting Storr’s morphological insights and newly acquired genetic evidence, in addition to a thorough re-examination of morphological traits, our study provides a robust foundation to raise Storr’s morphological subspecies into full species based upon multiple lines of evidence. Such an approach applied to other subspecies in the Australian herpetofauna also may result in revised taxonomies

"Basic Income is an idea whose time has come": But why here, why now, and in what way?

That Basic Income has received increased attention recently is noted in both academic and media discourse. A critical question about this attention is whether it amounts to more than “just a fad”. Contesting the label of “fad”, this thesis argues that the contemporary attention to Basic Income emerges through interlinked debates around the social understanding of work and the extent of the State. This argument is developed from semi-structured interviews with stakeholders who have relevant expertise in and around the Basic Income discourse, as well as thematic analysis of print media discussion of Basic Income in 2015 – 2017. This thesis examines the significance of the attention through the framework developed by Levitas as the Imaginary Reconstitution of Society. That is, it considers the discourse around Basic Income as fragmentary utopias, containing a mixture of critiques of the present, visions of the future “good society”, and policy proposals to move between the two. This leads to the conclusions that (i) the attention to Basic Income is rather attention to a plurality of Basic Incomes, with different purposes and bases, and (ii) that Basic Income cannot be understood as a policy in isolation, but instead as a part of a broader policy platform

Mediating exposure in public interactions

Mobile computing and public interactions together open up a new range of challenges in interaction design. To date a very gregarious model of interaction has been assumed. However, the public setting will invoke feelings of shyness and a desire to control the personal exposure associated with interactions. In this paper we discuss these issues and our initial tests of a system which affords a control beyond "engage or don't engage"