18,871 research outputs found
Evaporation waves in superheated dodecane
We have observed propagating adiabatic evaporation waves in superheated liquid dodecane, C_(12)H_(26). Experiments were performed with a rapid decompression apparatus at initial temperatures of 180–300°C. Saturated dodecane in a tube was suddenly depressurized by rupturing a diaphragm. Motion pictures and still photographic images, and pressure and temperature data were obtained during the evaporation event that followed depressurization. Usually, a front or wave of evaporation started at the liquid free surface and propagated into the undisturbed regions of the metastable liquid. The evaporation wave front moved with a steady mean velocity but the front itself was unstable and fluctuating in character. At low superheats, no waves were observed until a threshold superheat was exceeded. At moderate superheats, subsonic downstream states were observed. At higher superheats, the downstream flow was choked, corresponding to a Chapman–Jouguet condition. At the most extreme superheat tested, a vapour content of over 90% was estimated from the measured data, indicating a nearly complete evaporation wave. Our results are interpreted by modelling the evaporation wave as a discontinuity, or jump, between a superheated liquid state and a two-phase liquid–vapour downstream state. Reasonable agreement is found between the model and observations; however, there is a fundamental indeterminacy that prevents the prediction of the observed wave speeds
Coupled Cluster Channels in the Homogeneous Electron Gas
We discuss diagrammatic modifications to the coupled cluster doubles (CCD)
equations, wherein different groups of terms out of rings, ladders,
crossed-rings and mosaics can be removed to form approximations to the coupled
cluster method, of interest due to their similarity with various types of
random phase approximations. The finite uniform electron gas is benchmarked for
14- and 54-electron systems at the complete basis set limit over a wide density
range and performance of different flavours of CCD are determined. These
results confirm that rings generally overcorrelate and ladders generally
undercorrelate; mosaics-only CCD yields a result surprisingly close to CCD. We
use a recently developed numerical analysis [J. J. Shepherd and A. Gr\"uneis,
Phys. Rev. Lett. 110, 226401 (2013)] to study the behaviours of these methods
in the thermodynamic limit. We determine that the mosaics, on forming the
Brueckner Hamltonian, open a gap in the effective one-particle eigenvalues at
the Fermi energy. Numerical evidence is presented which shows that methods
based on this renormalisation have convergent energies in the thermodynamic
limit including mosaic-only CCD, which is just a renormalised MP2. All other
methods including only a single channel, namely ladder-only CCD, ring-only CCD
and crossed-ring-only CCD, appear to yield divergent energies; incorporation of
mosaic terms prevents this from happening.Comment: 9 pages, 4 figures, 1 table. Comments welcome: [email protected]
Regional Unemployment Disparities.
In this paper we examine the nature of disparities in regional (State) unemployment rates in Australia over the period 1978-1999 and their relationship to the national unemployment rate. As a measure of dispersion we use the sum of the (weighted) deviations of regional unemployment rates from the national rate. We show that this figure may be interpreted as the number of new jobs or labour force movements that would be needed to even out unemployment rates between regions, expressed as a proportion of the total number currently employed in all regions. Using co-integration analysis, we find that there is a (long-run) relationship between the degree of dispersion in the regional unemployment rates and the level of the national unemployment rate. The relationship between the two is negative implying that, as the national unemployment rate falls, micro and/or differentiated labour markets policies need to bite harder (and affect proportionately more people) if equity in unemployment across regions is to be maintained. We also find that the trade-off between dispersion and unemployment has become steeper in the period following significant deregulation of the Australian economy in the early Nineteen-Eighties. It would appear likely that this reflects an increase in differences in the Natural Rate of Unemployment between the regions since that time.UNEMPLOYMENT ; REGIONAL DEVELOPMENT
A universally programmable Quantum Cellular Automaton
We discuss the role of classical control in the context of reversible quantum
cellular automata. Employing the structure theorem for quantum cellular
automata, we give a general construction scheme to turn an arbitrary cellular
automaton with external classical control into an autonomous one, thereby
proving the computational equivalence of these two models. We use this
technique to construct a universally programmable cellular automaton on a
one-dimensional lattice with single cell dimension 12.Comment: 4 pages, 4 figures, minor changes in introduction, fixed typos,
accepted for publication in Physical Review Letter
Water utilization, evapotranspiration and soil moisture monitoring in the south east region of south Australia
There are no author-identified significant results in this report
Bi-Directional Relativistic Jets of the Radio Galaxy 1946+708: Constraints on the Hubble Constant
We present measurements of bi-directional motions in the jets of the radio
galaxy 1946+708 at z=0.101. This is a Compact Symmetric Object with striking
S-symmetry. Sensitive 15 GHz observations reveal a compact component at the
center of symmetry with a strongly inverted spectrum, that we identify as the
core. From five 4.9 GHz observations spread over 4 years we have determined the
velocities of four compact jet components. If simple kinematic models can be
applied then the inclination of the source and the bulk jet velocity can be
directly determined for any assumed value of the Hubble constant. Conversely,
the measurements already place constraints on the Hubble constant, and we show
how further observations of 1946+708 can yield an increasingly accurate
determination of H_0.Comment: in press at ApJ Letters, 12 page LaTex document includes 5 postscript
figure
When Sacred Space becomes a Heritage Place: Pilgrimage, Worship, and Tourism in Contemporary China
When promoted at sites that have traditionally been religious in character, heritage tourism evokes questions of intentionality, commodification, and authenticity. In particular, tourism at such sites is alleged to flatten out local practices, cause social problems, and commercialise the sacred. In short, local cultural practices are presumed to be transformed for the worse by tourism, a presumption which implies the existence of pristine pre-tourist cultures which can serve as baseline tools for measuring the impact of this touristic degradation. In this paper I address these concerns by examining tourism at a particular Chinese religious site, recently designated as a national park and world heritage site, the Buddhist pilgrimage destination of Mount Wutai (Ch. Wutai Shan). In 1982 the Wutai area was designated one of China’s first national parks and in 2009 was inscribed on UNESCO’s world heritage list. In the last two decades Wutai Shan has become one of the most visited religious destinations in northern China, primarily by citizens of the People’s Republic of China (PRC). According to local, provincial, and national authorities, these overwhelmingly ethnic Han Chinese visitors are tourists, not pilgrims. Although the extent to which they identify as Buddhists is unclear, religious practice is widespread among visitors. Moreover, this practice is not hidden, since the state is very much present at Wutai Shan. State heritage policies at the site are designed to protect this as a heritage space, and thus, align with broad UNESCO preservation goals, particularly spatial arrangements. However, unlike UNESCO, local, provincial, and national authorities do not view tourism as a threat to the ‘heritage’ of Wutai Shan. Instead, by eliminating (as a direct effect of UNESCO management recommendations) a vibrant informal local economy structured around pilgrimage, state officials (particularly provincial and local officials), aim to ‘clean up’ this space, spur tourism, and capture a significant share of the resulting revenues. The net result is a situation in which state policies simultaneously enable mass tourism, manage religious practice, and seek to guide visitor experiences. What remains is not a sacred place somehow ruined by tourism and / or commodification, but a quotidian religious space at which the thick happenings of Buddhism-in-practice have been curtailed but not eliminated. In short, the enactment of this sacred place remains, albeit under the careful gaze of various parts of the state
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