7,410 research outputs found
Comparison of Compression Schemes for CLARA
CLARA (Compact Linear Advanced Research Accelerator)at Daresbury Laboratory
is proposed to be the UK's national FEL test facility. The accelerator will be
a ~250 MeV electron linac capable of producing short, high brightness electron
bunches. The machine comprises a 2.5cell RF photocathode gun, one 2 m and three
5 m normal conducting S-band (2998MHz) accelerating structures and a variable
magnetic compression chicane. CLARA will be used as a test bed for novel FEL
configurations. We present a comparison of acceleration and compression schemes
for the candidate machine layout.Comment: 3 pages, 5 figures, IPAC 201
Strategies for Competing in Future Tourism Markets
A key to the development of the travel and tourist industry is increasing efficiency. Efficiency will be directly related to increases in management know-how. Know-how will come in the form of new and better ways of stimulating innovation and creativity in the design of the industry\u27s products
Downhill Ski Market Development: An Uphill Battle
Canada\u27s ski industry has been facing flattening market demand and declining revenues and profitability for the past few years. In response, the Canadian Ski Council undertook a major research initiative to provide the market intelligence necessary to prepare a comprehensive and targeted marketing campaign. This study provides insights into the findings emanating from research on high potential non-skiers, and the ways in which the research was used to establish a nation-wide program designed to bring more skiers to the ski slopes
Polymer blend miscibility
A number of quasi-binary homopolymer blends have been investigated
with regard to their miscibility. The blends consisted of
poly(epichlorohydrin) (PEPC) mixed with a range of poly(methacrylate)
polymers:- poly(methyl methacrylate); poly(ethoxyethyl methacrylate);
poly(tetrahydrofurfuryl methacrylate) and poly(glycidyl methacrylate)
(PGMA). It was found that the state of mixing of the systems varied
with the structure of the ester side chain, embracing a number of
miscibility states. It has been postulated that the observed miscibility
in the system PGMA/PEPC is due to the presence of a small
specific interaction between the species.
A second category of blend investigated comprised of a homopolymer
(PEPC) and a random copolymer. In two cases the copolymers (styreneco-
methacrylonitrile; methyl methacrylate-co-methacrylonitrile) were
chosen such that the cohesive energy density of PEPC lay between
those of the comonomers. This led to the observation of a number
of miscibility states for the systems, depending upon the copolymer
composition. Analysis of these systems and similar examples in the
literature was conducted using the mean-field approach. A reasonable
accord between theory and experiment was found when the role of both
specific interactions and free-volume terms was negligible.
A third type of copolymer (glycidyl methacrylate-co-methyl
methacrylate) was found to be only partially miscible with PEPC.
This was due to the small GMA/PEPC interaction and the tendency of
the copolymer to diverge from the copolymerisation equation at high
GMA concentrations.
The experimental probe for miscibility has been the glass
transition temperature. This was determined using Differential
Thermal Analysis, Dynamic Mechanical Thermal Analysis and to a lesser
extent, Dielectric Relaxation.
The phenomenon of partial miscibility, in which phase composition
varies with overall blend composition, has been discussed. It has
been postulated that this widely observed behaviour is due to a
non-equilibrium phase separation process. The inadequacy of existing
relationshi in describing the variation of the glass transition
temperature of a miscible blend with composition has been highlighted.
Furthermore, the importance of the transition width as an indicator
of miscibility has been stressed
Recruitment and Retention Insights for the Hotel Industry
Recruiting talented managerial employees for the hotel industry is a constant challenge. Identifying and training supervisors and junior level managers for senior positions seems to be one solution. The authors explore the career influences confronting these individuals and make recommendations for recruitment and retention
Government Funding in Australian Independent Schools
This chapter gives a history of government funding of Australian independent schools with a focus on Seventh-day Adventist education identities. It covers the evolution of the methods of funding, the politics of funding, the controversies from interest groups on such funding, and Ellen White’s advice on receiving government funding for Adventist schools
Time-Series Analysis of Supergranule Characterstics at Solar Minimum
Sixty days of Doppler images from the Solar and Heliospheric Observatory (SOHO) / Michelson Doppler Imager (MDI) investigation during the 1996 and 2008 solar minima have been analyzed to show that certain supergranule characteristics (size, size range, and horizontal velocity) exhibit fluctuations of three to five days. Cross-correlating parameters showed a good, positive correlation between supergranulation size and size range, and a moderate, negative correlation between size range and velocity. The size and velocity do exhibit a moderate, negative correlation, but with a small time lag (less than 12 hours). Supergranule sizes during five days of co-temporal data from MDI and the Solar Dynamics Observatory (SDO) / Helioseismic Magnetic Imager (HMI) exhibit similar fluctuations with a high level of correlation between them. This verifies the solar origin of the fluctuations, which cannot be caused by instrumental artifacts according to these observations. Similar fluctuations are also observed in data simulations that model the evolution of the MDI Doppler pattern over a 60-day period. Correlations between the supergranule size and size range time-series derived from the simulated data are similar to those seen in MDI data. A simple toy-model using cumulative, uncorrelated exponential growth and decay patterns at random emergence times produces a time-series similar to the data simulations. The qualitative similarities between the simulated and the observed time-series suggest that the fluctuations arise from stochastic processes occurring within the solar convection zone. This behavior, propagating to surface manifestations of supergranulation, may assist our understanding of magnetic-field-line advection, evolution, and interaction
Properties of Supergranulation During the Solar Minima of Cycles 22/23 and 23/24
The solar minimum at the transition from cycle 23 to 24 was notable for its low level of activity and its extended duration. Among the various fields of study, the evolution of the solar convection zone may provide insight into the causes and consequences of this recent minimum. This study continues previous investigations of the characteristics of solar supergranulation, a convection component strongly linked to the structure of the magnetic field, namely the time-evolution of the global mean of supergranule cell size, determined from spectral analysis of MDI Dopplergrams from the two previous solar minima. Analyses of the global mean of supergranule sizes show a quasi-oscillatory nature to the evolution of this particular supergranule characteristic. Performing similar analyses on realistic, synthetic Doppler images show similar time-dependent characteristics. We conclude that the observed fluctuations are not observational artifacts, and that an underlying trend exists within the evolution of the supergranulation network
G-133: A soft x ray solar telescope
The GOLDHELOX Project, NASA payload number G-133, is a robotic soft x ray solar telescope designed and built by an organization of undergraduate students. The telescope is designed to observe the sun at a wavelength of 171 to 181 A. Since we require observations free from atmospheric interference, the telescope will be launched in a NASA Get-Away-Special (GAS) canister with a Motorized Door Assembly (MDA). In this paper we primarily discuss the most important elements of the telescope itself. We also elaborate on some of the technical difficulties associated with doing good science in space on a small budget (about $100,000) and mention ways in which controlling the instrument environment has reduced the complexity of the system and thus saved us money
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