3,170 research outputs found
Numerical Simulation for Droplet Combustion Using Lagrangian Hydrodynamics
A predictive model of spray combustion must incorporate models for the wide variety of physical environments in a practical combustor. In regions where droplets are closely spaced, combustion resembles a diffusion flame; where they are well separated, an envelope or wake flame results. The relative velocity field between the fuel droplets and oxidizer in influences boundary layer development about the droplet, recirculating flow patterns, and droplet shape and stability. A model must encompass these interacting temporal and spatial effects as well as complicated combustor boundaries. The objective of the current work is to develop the triangular gridding method for describing the individual and collective properties of vaporizing and burning fuel droplets
A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: Hipparcos-Tycho cool stars
The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is
indicative of very energetic, transient phenomena, associated with energy
release via magnetic reconnection. We present a uniform, large-scale survey of
X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its
associated data products provide an excellent basis for a comprehensive and
sensitive survey of stellar flares - both from targeted active stars and from
those observed serendipitously in the half-degree diameter field-of-view of
each observation. The 2XMM Catalogue and the associated time-series
(`light-curve') data products have been used as the basis for a survey of X-ray
flares from cool stars in the Hipparcos Tycho-2 catalogue. In addition, we have
generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray
light-curves. Where available, we have compared XMM OM UV/optical data with the
X-ray light-curves. Our sample contains ~130 flares with well-observed
profiles; they originate from ~70 stars. The flares range in duration from ~1e3
to ~1e4 s, have peak X-ray fluxes from ~1e-13 to ~1e-11 erg/cm2/s, peak X-ray
luminosities from ~1e29 to ~1e32 erg/s, and X-ray energy output from ~1e32 to
~1e35 erg. Most of the ~30 serendipitously-observed stars have little
previously reported information. The hardness-ratio plots clearly illustrate
the spectral (and hence inferred temperature) variations characteristic of many
flares, and provide an easily accessible overview of the data. We present flare
frequency distributions from both target and serendipitous observations. The
latter provide an unbiased (with respect to stellar activity) study of flare
energetics; in addition, they allow us to predict numbers of stellar flares
that may be detected in future X-ray wide-field surveys. The serendipitous
sample demonstrates the need for care when calculating flaring rates.Comment: 26 pages, 24 figures. Additional tables and figures available as 4
ancillary files. To be published in Astronomy and Astrophysic
Established-Outsider Relations and the Socio-Genesis of the Museum
It is surprising that little research has been conducted by Eliasians on museums and that, with some exceptions, academics working on museums do not cite The Civilizing Process. All the more so given that: (i) museum research supports Elias’s claim that elements of modernity originated in court societies, (ii) the nineteenth-century museum was a leading edge of the West’s belief in itself as a singularly civilized place and (iii) there is a contradiction between the museum’s universalism and its latent capacity to stigmatize some visitors as uncivilized outsiders. Indeed, Elias’s theory of established-outsider relations offers profound insights into the museum dimension of social stigma and the socio-genesis of the museum. First, an Eliasian perspective illuminates the relationship between museums and the peculiar structures of feeling that flowed from the interdependencies of modernization. Secondly, in studying European upper classes, he stressed the co-existence of different propertied strata within nineteenth-century states. This explains the apparent inchoateness of European national museums as they emerged at the interface of ruling dynastic elites and upwardly mobile bourgeois outsiders. Thirdly, documentary evidence reveals the museum to be a place where middle class people incorporated and transformed a courtly habitus whilst simultaneously stigmatizing both aristocratic and working class ways of living the body. Finally, Elias elaborated dynamic models of established-outsider relations, emphasizing their ‘complex polyphony’ as the key to explaining the power to stigmatize. The museum performed that polyphony at the interface of established-outsider relations; it could be said that they were the very causes of museums
Testing \u3cem\u3eThe Limits of Law Enforcement\u3c/em\u3e
A Review of The Limits of Law Enforcement by Hans Zeise
Numerical simulations of fuel droplet flows using a Lagrangian triangular mesh
The incompressible, Lagrangian, triangular grid code, SPLISH, was converted for the study of flows in and around fuel droplets. This involved developing, testing and incorporating algorithms for surface tension and viscosity. The major features of the Lagrangian method and the algorithms are described. Benchmarks of the algorithms are given. Several calculations are presented for kerosene droplets in air. Finally, extensions which make the code compressible and three dimensional are discussed
The challenges of change:Exploring the dynamics of police reform in Scotland
Despite a long tradition of pessimism regarding the scope for meaningful change in police practices, recent structural reforms to police organizations in several European countries suggest that significant change in policing is possible. Drawing on recent research into the establishment and consequences of a national police force in Scotland, this article uses instrumental, cultural and myth perspectives taken from organization theory to examine how change happened and with what effects. It highlights how police reform involves a complex interplay between the strategic aims of government, the cultural norms of police organizations and the importance of alignment with wider views about the nature of the public sector. The article concludes by identifying a set of wider lessons from the experience of organizational change in policing
- …