1,244 research outputs found
CIS-lunar space infrastructure lunar technologies: Executive summary
Technologies necessary for the creation of a cis-Lunar infrastructure, namely: (1) automation and robotics; (2) life support systems; (3) fluid management; (4) propulsion; and (5) rotating technologies, are explored. The technological focal point is on the development of automated and robotic systems for the implementation of a Lunar Oasis produced by Automation and Robotics (LOAR). Under direction from the NASA Office of Exploration, automation and robotics were extensively utilized as an initiating stage in the return to the Moon. A pair of autonomous rovers, modular in design and built from interchangeable and specialized components, is proposed. Utilizing a buddy system, these rovers will be able to support each other and to enhance their individual capabilities. One rover primarily explores and maps while the second rover tests the feasibility of various materials-processing techniques. The automated missions emphasize availability and potential uses of Lunar resources, and the deployment and operations of the LOAR program. An experimental bio-volume is put into place as the precursor to a Lunar environmentally controlled life support system. The bio-volume will determine the reproduction, growth and production characteristics of various life forms housed on the Lunar surface. Physicochemical regenerative technologies and stored resources will be used to buffer biological disturbances of the bio-volume environment. The in situ Lunar resources will be both tested and used within this bio-volume. Second phase development on the Lunar surface calls for manned operations. Repairs and re-configuration of the initial framework will ensue. An autonomously-initiated manned Lunar oasis can become an essential component of the United States space program
Internal quantum reference frames for finite Abelian groups
Employing internal quantum systems as reference frames is a crucial concept
in quantum gravity, gauge theories and quantum foundations whenever external
relata are unavailable. In this work, we give a comprehensive and
self-contained treatment of such quantum reference frames (QRFs) for the case
when the underlying configuration space is a finite Abelian group,
significantly extending our previous work (Quantum 5, 530 (2021)). The
simplicity of this setup admits a fully rigorous quantum information-theoretic
analysis, while maintaining sufficient structure for exploring many of the
conceptual and structural questions also pertinent to more complicated setups.
We exploit this to derive several important structures of constraint
quantization with quantum information-theoretic methods and to reveal the
relation between different approaches to QRF covariance. In particular, we
characterize the "physical Hilbert space" -- the arena of the
"perspective-neutral" approach -- as the maximal subspace that admits
frame-independent descriptions of purifications of states. We then demonstrate
the kinematical equivalence and, surprising, dynamical inequivalence of the
"perspective-neutral" and the "alignability" approach to QRFs. While the former
admits unitaries generating transitions between arbitrary subsystem relations,
the latter, remarkably, admits no such dynamics when requiring
symmetry-preservation. We illustrate these findings by example of interacting
discrete particles, including how dynamics can be described "relative to one of
the subsystems".Comment: 22 pages, 1 figure. V2: close to published versio
Untersuchung der Flusswasserinfiltration in voralpinen Schottern mittels Zeitreihenanalyse
Kurzfassung: Grundwasserfassungen in der Nähe von Flüssen können durch die Infiltration von Flusswasser beeinflusst werden. Aus Sicht des Trinkwasserschutzes interessiert vor allem, welcher Anteil des geförderten Wassers aus dem Fluss stammt und wie lange das Flussinfiltrat im Grundwasserleiter verbleibt, bevor es gefördert wird. Hierzu können Markierversuche durchgeführt werden, die jedoch bei größeren Flüssen mit einem erheblichen Stoffeintrag verbunden sind. Als Alternative zu Markierversuchen stellen wir Methoden vor, um aus Zeitreihen der elektrischen Leitfähigkeit und der Temperatur quantitative Aussagen zu Mischungsverhältnissen und Aufenthaltszeiten abzuleiten. Wir empfehlen ein mehrstufiges Vorgehen bestehend aus: (1) einer qualitativen Analyse, (2) der spektralen Ermittlung des saisonalen Temperatur- und Leitfähigkeitsverlaufs, (3) einer Kreuzkorrelationsanalyse und (4) der nicht-parametrischen Dekonvolution der Zeitreihen. Wir wenden diese Methoden an drei Standorten im Grundwasserstrom des Thurtales im schweizerischen Mittelland an. An Standorten ohne gute Flussanbindung oder mit exfiltrierenden Verhältnissen können die aufwändigen Zeitreihenanalysen nicht angewendet werden, die Messreihen zeigen jedoch die entsprechenden Verhältnisse an. An Standorten mit dauerhafter Flussinfiltration kann aus den Zeitreihen die Durchbruchskurve eines Markierversuches rekonstruiert werden, ohne einen künstlichen Markierstoff in den Fluss geben zu müsse
Revenue divergence and competitive balance in a divisional sports league
The North American model of resource allocation in professional sports leagues is adapted for English (association) football. The theoretical relationship between revenue and competitive balance is shown to be robust with respect to changes in teams’ objectives and labour market conditions. Empirical revenue functions are reported for 1926-1999. These indicate a shift in the composition of demand favouring big-city teams and an increase in the sensitivity of revenue to performance. An analysis of match results in the FA Cup competition suggests an increase in competitive imbalance between teams at different levels of the league’s divisional hierarchy, as the theory suggests
Progress in development of tapes and magnets made from Bi-2223 superconductors
Long lengths of (Bi,Pb)2Sr2Ca2Cu3O(x) tapes made by powder-in-tube processing have been wound into coils. Performance of the coils has been measured at temperatures of 4.2 to 77 K, and microstructures have been examined by x-ray diffraction and electron microscopy and then related to superconducting properties. A summary of recent results and an overview of future goals are presented
Quantum Relativity of Subsystems
One of the most basic notions in physics is the partitioning of a system into
subsystems, and the study of correlations among its parts. In this work, we
explore these notions in the context of quantum reference frame (QRF)
covariance, in which this partitioning is subject to a symmetry constraint. We
demonstrate that different reference frame perspectives induce different sets
of subsystem observable algebras, which leads to a gauge-invariant,
frame-dependent notion of subsystems and entanglement. We further demonstrate
that subalgebras which commute before imposing the symmetry constraint can
translate into non-commuting algebras in a given QRF perspective after symmetry
imposition. Such a QRF perspective does not inherit the distinction between
subsystems in terms of the corresponding tensor factorizability of the
kinematical Hilbert space and observable algebra. Since the condition for this
to occur is contingent on the choice of QRF, the notion of subsystem locality
is frame-dependent.Comment: 8+9 pages, 1 figur
Staring into the abyss? The state of UK rugby's Super League
Rugby League's Super League was formed in 1995, due to unprecedented turmoil experienced in rugby league in Australia and a desire to run a season parallel to the Australian game during the British summer. The predicted outcomes of the Super League included greater uncertainty of outcome, increased attendances, and higher revenues for clubs, ultimately leading to the transformation of rugby league from a northern minority sport into a national/international sport. However, twenty years on, it appears that the Super League is running short of the objectives that it set itself. This paper analyses the financial health of Super League clubs alongside trends in attendance and participation. In summary, all three indicators of performance are poor in relation to the objectives set. These factors point to a bleak future for the sport and rugby league needs to produce a sustainable business model to keep both the clubs and the sport alive
Development of Prototype HTS Components for Magnetic Suspension Applications
We have concentrated on developing prototype lengths of bismuth and thallium based silver sheathed superconductors by the powder-in-tube approach to fabricate high temperature superconducting (HTS) components for magnetic suspension applications. Long lengths of mono and multi filament tapes are presently being fabricated with critical current densities useful for maglev and many other applications. We have recently demonstrated the prototype manufacture of lengths exceeding 1 km of Bi-2223 multi filament conductor. Long lengths of thallium based multi-filament conductor have also been fabricated with practical levels of critical current density and improved field dependence behavior. Test coils and magnets have been built from these lengths and characterized over a range of temperatures and background fields to determine their performance. Work is in progress to develop, fabricate and test HTS windings that will be suitable for magnetic suspension, levitation and other electric power related applications
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