49 resultados para Spinning Spacecraft

em Queensland University of Technology - ePrints Archive


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Scaffolds manufactured from biological materials promise better clinical functionality, providing that characteristic features are preserved. Collagen, a prominent biopolymer, is used extensively for tissue engineering applications, because its signature biological and physico-chemical properties are retained in vitro preparations. We show here for the first time that the very properties that have established collagen as the leading natural biomaterial are lost when it is electro-spun into nano-fibres out of fluoroalcohols such as 1,1,1,3,3,3-hexafluoro-2-propanol or 2,2,2-trifluoroethanol. We further identify the use of fluoroalcohols as the major culprit in the process. The resultant nano-scaffolds lack the unique ultra-structural axial periodicity that confirms quarter-staggered supramolecular assemblies and the capacity to generate second harmonic signals, representing the typical crystalline triple-helical structure. They were also characterised by low denaturation temperatures, similar to those obtained from gelatin preparations ( p > 0.05). Likewise, circular dichroism spectra revealed extensive denaturation of the electro-spun collagen. Using pepsin digestion in combination with quantitative SDS-PAGE, we corroborate great losses of up to 99% of triple-helical collagen. In conclusion, electro-spinning of collagen out of fluoroalcohols effectively denatures this biopolymer, and thus appears to defeat its purpose, namely to create biomimetic scaffolds emulating the collagen structure and function of the extracellular matrix.

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Hayabusa, an unmanned Japanese spacecraft, was launched to study and collect samples from the surface of the asteroid 25143 Itokawa. In June 2010, the Hayabusa spacecraft completed it’s seven year voyage. The spacecraft and the sample return capsule (SRC) re-entered the Earth’s atmosphere over the central Australian desert at speeds on the order of 12 km/s. This provided a rare opportunity to experimentally investigate the radiative heat transfer from the shock-compressed gases in front of the sample return capsule at true-flight conditions. This paper reports on the results of observations from a tracking camera situated on the ground about 100 km from where the capsule experienced peak heating during re-entry.

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This paper presents an image-based visual servoing system that was used to track the atmospheric Earth re-entry of Hayabusa. The primary aim of this ground based tracking platform was to record the emission spectrum radiating from the superheated gas of the shock layer and the surface of the heat shield during re-entry. To the author's knowledge, this is the first time that a visual servoing system has successfully tracked a super-orbital re-entry of a spacecraft and recorded its pectral signature. Furthermore, we improved the system by including a simplified dynamic model for feed-forward control and demonstrate improved tracking performance on the International Space Station (ISS). We present comparisons between simulation and experimental results on different target trajectories including tracking results from Hayabusa and ISS. The required performance for tracking both spacecraft is demanding when combined with a narrow field of view (FOV). We also briefly discuss the preliminary results obtained from the spectroscopy of the Hayabusa's heat shield during re-entry.

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In Australia, few fashion brands have intervened in the design of their products or the systems around their product to tackle environmental pollution and waste. Instead, support of charities (whether social or environmental) has become conflated with sustainability in the eyes of the public.However, three established Australian brands recently put forward initiatives which explicitly tackle the pre-consumer or post-consumer waste associated with their products. In 2011, Billabong, one of the largest surfwear companies in the world, developed a collection of board shorts made from recycled bottles that are also recyclable at end of life. The initiative has been promoted in partnership with Bob Marley’s son Rohan Marley, and the graphics of the board shorts reference the Rastafarian colours and make use of Marley’s song lyrics. In this way, the company has tapped into an aspect of surf culture linked to environmental activism, in which the natural world is venerated. Two mid-market initiatives, by Metalicus and Country Road, each have a social outcome that arguably aligns to the values of their middle-class consumer base. Metalicus is spear-heading a campaign for Australian garment manufacturers to donate their pre consumer waste – fabric off-cuts – to charity Open Family Australia to be manufactured into quilts for the homeless. Country Road has partnered with the Australian Red Cross to implement a recycling scheme in which consumers donate their old Country Road garments in exchange for a Country Road gift voucher. Both strategies, while tackling waste, tell an altruistic story in which the disadvantaged can benefit from the consumption habits of the middle-class. To varying degrees, the initiative chosen by each company feeds into the stories they tell about themselves and about the consumers who purchase their clothing. However, how can we assess the impact of these schemes on waste management in real terms, or indeed the worth of each scheme in the wider context of the fashion system? This paper will assess the claims made by the companies and analyse their efficacy, suggesting that a more nuanced assessment of green claims is required, in which ‘green’ comes in many tonal variations.

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The palette of fluorescent proteins (FPs) has grown exponentially over the past decade, and as a result, live imaging of cells expressing fluorescently tagged proteins is becoming more and more mainstream. Spinning disk confocal (SDC) microscopy is a high-speed optical sectioning technique and a method of choice to observe and analyze intracellular FP dynamics at high spatial and temporal resolution. In an SDC system, a rapidly rotating pinhole disk generates thousands of points of light that scan the specimen simultaneously, which allows direct capture of the confocal image with low-noise scientific grade-cooled charge-coupled device cameras, and can achieve frame rates of up to 1000 frames per second. In this chapter, we describe important components of a state-of-the-art spinning disk system optimized for live cell microscopy and provide a rationale for specific design choices. We also give guidelines of how other imaging techniques such as total internal reflection microscopy or spatially controlled photoactivation can be coupled with SDC imaging and provide a short protocol on how to generate cell lines stably expressing fluorescently tagged proteins by lentivirus-mediated transduction.

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In the Australian fashion industry, few fashion brands have intervened in the design of their products or the systems around their product to tackle environmental pollution and waste. Instead, support of charities (whether social or environmental) has become conflated with sustainability in the eyes of the public. Thus it is difficult to assess with any accuracy fashion brands’ response to sustainability. This article aims to address this through proposing a categorization system to structure the various interventions that a company may make. This system is applied to two case studies, analysing campaigns that respond to environmental sustainability by two established Australian brands, Country Road and Billabong. The case studies demonstrate how the interventions employed by a company, at least in the Australian context, are carefully developed to align with their brand story, revealing the interplay between the intangible aspects of a brand’s positioning and the tangible, measurable impacts of their garments.

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This paper applies concepts Deleuze developed in his ‘Postscript on the Societies of Control’, especially those relating to modulatory power, dividuation and control, to aspects of Australian schooling to explore how this transition is manifesting itself. Two modulatory machines of assessment, NAPLAN and My Schools, are examined as a means to better understand how the disciplinary institution is changing as a result of modulation. This transition from discipline to modulation is visible in the declining importance of the disciplinary teacher–student relationship as a measure of the success of the educative process. The transition occurs through seduction because that which purports to measure classroom quality is in fact a serpent of modulation that produces simulacra of the disciplinary classroom. The effect is to sever what happens in the disciplinary space from its representations in a luminiferous ether that overlays the classroom.

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Knowmore (House of Commons) is a large scale generative interactive installation that incorporates embodied interaction, dynamic image creation, new furniture forms, touch sensitivity, innovative collaborative processes and multichannel generative sound creation. A large circular table spun by hand and a computer-controlled video projection falls on its top, creating an uncanny blend of physical object and virtual media. Participants’ presence around the table and how they touch it is registered, allowing up to five people to collaboratively ‘play’ this deeply immersive audiovisual work. Set within an ecological context, the work subtly asks what kind of resources and knowledges might be necessary to move us past simply knowing what needs to be changed to instead actually embodying that change, whilst hinting at other deeply relational ways of understanding and knowing the world. The work has successfully operated in two high traffic public environments, generating a subtle form of interactivity that allows different people to interact at different paces and speeds and with differing intentions, each contributing towards dramatic public outcomes. The research field involved developing new interaction and engagement strategies for eco-political media arts practice. The context was the creation of improved embodied, performative and improvisational experiences for participants; further informed by ‘Sustainment’ theory. The central question was, what ontological shifts may be necessary to better envision and align our everyday life choices in ways that respect that which is shared by all - 'The Commons'. The methodology was primarily practice-led and in concert with underlying theories. The work’s knowledge contribution was to question how new media interactive experience and embodied interaction might prompt participants to reflect upon the kind of resources and knowledges required to move past simply knowing what needs to be changed to instead actually embodying that change. This was achieved through focusing on the power of embodied learning implied by the works' strongly physical interface (i.e. the spinning of a full size table) in concert with the complex field of layered imagery and sound. The work was commissioned by the State Library of Queensland and Queensland Artworkers Alliance and significantly funded by The Australia Council for the Arts, Arts Queensland, QUT, RMIT Centre for Animation and Interactive Media and industry partners E2E Visuals. After premiering for 3 months at the State Library of Queensland it was curated into the significant ‘Mediations Biennial of Modern Art’ in Poznan, Poland. The work formed the basis of two papers, was reviewed in Realtime (90), was overviewed at Subtle Technologies (2010) in Toronto and shortlisted for ISEA 2011 Istanbul and included in the edited book/catalogue ‘Art in Spite of Economics’, a collaboration between Leonardo/ISAST (MIT Press); Goldsmiths, University of London; ISEA International; and Sabanci University, Istanbul.

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Silylated layered double hydroxides (LDHs) were synthesized through a surfactant-free method involving an in situ condensation of silane with the surface hydroxyl group of LDHs during its reconstruction in carbonate solution. X-ray diffraction (XRD) patterns showed the silylation reaction occurred on the external surfaces of LDHs layers. The successful silylation was evidenced by 29Si cross-polarization magic-angle spinning nuclear magnetic resonance (29Si CP/MAS NMR) spectroscopy, attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy, and infrared emission spectroscopy (IES). The ribbon shaped crystallites with a “rodlike” aggregation were observed through transmission electron microscopy (TEM) images. The aggregation was explained by the T2 and T3 types of linkage between adjacent silane molecules as indicated in the 29Si NMR spectrum. In addition, the silylated products show high thermal stability by maintained Si related bands even when the temperature was increased to 1000 °C as observed in IES spectra.

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Smart materials, such as thin-film piezoelectric polymers, are interesting for potential applications on Gossamer spacecraft. This investigation aims to predict the performance and long-term stability of the piezoelectric properties of poly(vinylidene fluoride) (PVDF) and its copolymers under conditions simulating the low-Earthorbit environment. To examine the effects of temperature on the piezoelectric properties of PVDF, poly(vinylidenefluoride-co-trifluoroethylene), and poly(vinylidenefluoride-cohexafluoropropylene), the d33 piezoelectric coefficients were measured up to 160 8C, and the electric displacement/electric field (D–E) hysteresis loops were measured from �80 to þ110 8C. The room-temperature d33 coefficient of PVDF homopolymer films, annealed at 50, 80, and 125 8C, dropped rapidly within a few days of thermal exposure and then remained unchanged. In contrast, the TrFE copolymer exhibited greater thermal stability than the homopolymer, with d33 remaining almost unchanged up to 125 8C. The HFP copolymer exhibited poor retention of d33 at temperatures above 80 8C. In situ D–E loop measurements from �80 to þ110 8C showed that the remanent polarization of the TrFE copolymer was more stable than that of the PVDF homopolymer. D–E hysteresis loop and d33 results were also compared with the deflection of the PVDF homopolymer and TrFE copolymer bimorphs tested over a wide temperature range.

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The effects of simulated low earth orbit conditions on vinylidene-fluoride based thin-film piezoelectrics for use in lightweight, large surface area spacecraft such as telescope mirrors and antennae is presented. The environmental factors considered as having the greatest potential to cause damage are temperature, atomic oxygen and vacuum UV radiation. Using the piezoelectric strain coefficients and bimorph deflection measurements the piezoelectric performance over the temperature range -100 to +150°C was studied. The effects of simultaneous AO/VUV exposure were also examined and films characterized by their piezoelectric, surface, and thermal properties. Two fluorinated piezoelectric polymers, poly(vinylidene fluoride) and poly(vinylidene fluoride-co-trifluoroethylene), were adversely affected at elevated temperatures due to depoling caused by randomization of the dipole orientation, while AO/VUV contributed little to depoling but did cause significant surface erosion and, in the case of P(VDF-TrFE), bulk crosslinking. These results highlight the importance of materials selection for use in space environments.