27,852 research outputs found
Microcomputerized electric field meter diagnostic and calibration system
A computerized field meter calibration system which includes an apparatus for testing the calibration of field meters normally utilized for measuring electromagnetic field potentials is described. A reference voltage is applied to the field meter for causing signals to be produced on the output terminals thereof. A bank of relays is provided for selectively connecting output terminals of the field meter to a multiplexer by means of a digital voltmeter and an oscilloscope. A frequency-shift-keyed receiver is also connected to one of the terminals of the field meter for transmitting and converting a frequency shift keyed signal to a digital signal which is, subsequently, applied to the multiplexer
A new method for treating optimal trajectories with restricted segments
New method for treating optimal trajectorie
Recommended from our members
Remote sensing of intertidal morphological change in Morecambe Bay, U.K., between 1991 and 2007
Tidal Flats are important examples of extensive areas of natural environment that remain relatively unaffected by man. Monitoring of tidal flats is required for a variety of purposes. Remote sensing has become an established technique for the measurement of topography over tidal flats. A further requirement is to measure topographic changes in order to measure sediment budgets. To date there have been few attempts to make quantitative estimates of morphological change over tidal flat areas. This paper illustrates the use of remote sensing to measure quantitative and qualitative changes in the tidal flats of Morecambe Bay during the relatively long period 1991–2007. An understanding of the patterns of sediment transport within the Bay is of considerable interest for coastal management and defence purposes. Tidal asymmetry is considered to be the dominant cause of morphological change in the Bay, with the higher currents associated with the flood tide being the main agency moulding the channel system. Quantitative changes were measured by comparing a Digital Elevation Model (DEM) of the intertidal zone formed using the waterline technique applied to satellite Synthetic Aperture Radar (SAR) images from 1991–1994, to a second DEM constructed from airborne laser altimetry data acquired in 2005. Qualitative changes were studied using additional SAR images acquired since 2003. A significant movement of sediment from below Mean Sea Level (MSL) to above MSL was detected by comparing the two Digital Elevation Models, though the proportion of this change that could be ascribed to seasonal effects was not clear. Between 1991 and 2004 there was a migration of the Ulverston channel of the river Leven north-east by about 5 km, followed by the development of a straighter channel to the west, leaving the previous channel decoupled from the river. This is thought to be due to independent tidal and fluvial forcing mechanisms acting on the channel. The results demonstrate the effectiveness of remote sensing for measurement of long-term morphological change in tidal flat areas. An alternative use of waterlines as partial bathymetry for assimilation into a morphodynamic model of the coastal zone is also discussed
Body and canard effects on an attached-flow maneuver wing at Mach 1.62
A wing-body-canard configuration was tested at a Mach number of 1.62 by using both a cambered and an uncambered wing. The cambered wing was designed to produce efficient high lift by using attached supercritical crossflow and was originally tested as an isolated wing. The uncambered wing has the same planform and essentially the same thickness distribution as the cambered wing. The experiment determined the effects of a body and canards on both wings. The experimental data showed that both the body and the canards influenced the wing pressure levels, but that the attached supercritical crossflow, which was achieved in the isolated cambered-wing test, was maintained in the presence of a body and canards. Tables of experimental pressure, force, and moment data are included, as well as photographs of oil flow patterns on the upper surface
Supersonic, nonlinear, attached-flow wing design for high lift with experimental validation
Results of the experimental validation are presented for the three dimensional cambered wing which was designed to achieve attached supercritical cross flow for lifting conditions typical of supersonic maneuver. The design point was a lift coefficient of 0.4 at Mach 1.62 and 12 deg angle of attack. Results from the nonlinear full potential method are presented to show the validity of the design process along with results from linear theory codes. Longitudinal force and moment data and static pressure data were obtained in the Langley Unitary Plan Wind Tunnel at Mach numbers of 1.58, 1.62, 1.66, 1.70, and 2.00 over an angle of attack range of 0 to 14 deg at a Reynolds number of 2.0 x 10 to the 6th power per foot. Oil flow photographs of the upper surface were obtained at M = 1.62 for alpha approx. = 8, 10, 12, and 14 deg
A systematic review of the contribution of art education to cultural learning in learners aged 5–16
This review was prompted by a concern to collect
evidence about art education and cultural identity formation. Art is widely viewed as one of the main communication systems in most cultures and as a medium for transmission and transformation of culture. In the past, art curricula tended to be dominated by an elite tradition of western fine art.
The wider range of cultural practices and identifications being advocated as a result of multicultural reform raises practical difficulties for art teachers. These are widely debated: for example, how to teach cultural heritage and which kind of cultural content to include. Governments are increasingly advocating the use of art education to redress pressing societal problems, such as social exclusion and culture conflict. However, the nature of such curriculum interventions and their impact on learners’ cultural identifications is unclear.
This systematic review covers a section of the
research literature on art and cultural learning.
The literature is first described in a map and then
assessed for quality and synthesised.
Aim
The aim of the review is to provide evidence about
the contribution of art to cultural education for
learners aged 5–16 (i.e. understanding of self and
others in relation to culture).
Conclusions
Policy
Probably the most significant finding is that the
extensive literature discussing the positive contribution of art to cultural learning in the United Kingdom is not supported by empirical research. The review highlights the worrying possibility therefore that publicly funded policy in art and cultural understanding is without a significant evidence base.
Practice
The majority of studies included in this review are
doctoral theses. They were carried out in collaboration with school teachers and were practice based. Although this probably caused them to be quite small scale, they provide detailed examples of experimental curricula. This is perhaps indicative of a desire by some practitioners for research evidence to guide them on the topic.
Research
The research reports included in this review are
small-scale evaluations of curriculum experiments
by the participants. There was very little hard,
empirical evidence in them to support claims that
art education affects positive changes in learners’
understanding of others and self. This suggests
that more reliable and valid research in this area of the art curriculum needs to be carried out. The Arts Council of England (2002), for example, could see it as one of its functions to investigate systematically the impact of art education interventions on identity formation and cross-cultural understanding as part of its Creative Partnership Scheme
Comparing Community Structure to Characteristics in Online Collegiate Social Networks
We study the structure of social networks of students by examining the graphs
of Facebook "friendships" at five American universities at a single point in
time. We investigate each single-institution network's community structure and
employ graphical and quantitative tools, including standardized pair-counting
methods, to measure the correlations between the network communities and a set
of self-identified user characteristics (residence, class year, major, and high
school). We review the basic properties and statistics of the pair-counting
indices employed and recall, in simplified notation, a useful analytical
formula for the z-score of the Rand coefficient. Our study illustrates how to
examine different instances of social networks constructed in similar
environments, emphasizes the array of social forces that combine to form
"communities," and leads to comparative observations about online social lives
that can be used to infer comparisons about offline social structures. In our
illustration of this methodology, we calculate the relative contributions of
different characteristics to the community structure of individual universities
and subsequently compare these relative contributions at different
universities, measuring for example the importance of common high school
affiliation to large state universities and the varying degrees of influence
common major can have on the social structure at different universities. The
heterogeneity of communities that we observe indicates that these networks
typically have multiple organizing factors rather than a single dominant one.Comment: Version 3 (17 pages, 5 multi-part figures), accepted in SIAM Revie
Extended Molecular Gas in the Nearby Starburst Galaxy Maffei 2
We present a 9'x9' fully-sampled map of the CO J=1-0 emission in the nearby
starburst galaxy Maffei 2 obtained at the Five College Radio Astronomy
Observatory. The map reveals previously known strong CO emission in the central
starburst region as well as an extended asymmetric distribution with bright CO
lines at the ends of the bar and in a feature at the north-east edge of the
molecular disk. This northern feature, proposed previously to be an interacting
companion galaxy, could be a dwarf irregular galaxy, although the CO data are
also consistent with the feature being simply an extension of one of the spiral
arms. We estimate the total molecular gas mass of Maffei 2 to be (1.4-1.7)x10^9
Mo or ~3-4% of its dynamical mass. Adopting the recently determined lower value
for the CO-to-H2 conversion factor in the central region, our data lead to the
surprising result that the largest concentrations of molecular gas in Maffei 2
lie at the bar ends and in the putative dwarf companion rather than in the
central starburst. A gravitational stability analysis reveals that the extended
disk of Maffei 2 lies above the critical density for star formation; however,
whether the central region is also gravitationally unstable depends both on the
details of the rotation curve and the precise value of the CO-to-H2 conversion
factor in this region.Comment: accepted to ApJ (Sept 10 2004 issue
- …