658 research outputs found
Increasing Parental Involvement through Internet Instruction
The purpose of the project was to develop a curriculum of Internet instruction for parents of Washington Middle School students. Through a review of the current literature it was found that the recurring lack of communication between parents, students and educators was identified as a barrier for involving families in their students\u27 education. To overcome this barrier four sessions of instruction and practice were developed to increase the families\u27 ability to communicate with their children\u27s educators. The sessions introduce the basic layout and function of computers, the Internet, using email for communication, skills vital for finding information on the internet, and local, free access internet providers
Aerodynamic Interference on Finned Slender Body
Aerodynamic interference can occur between high-speed slender bodies when in close proximity. A complex flowfield develops where shock and expansion waves from a generator body impinge upon the adjacent receiver body and modify its aerodynamic characteristics in comparison to the isolated case. The aim of this research is to quantify and understand the multibody interference effects that arise between a finned slender body and a second disturbance generator body. A parametric wind tunnel study was performed in which the effects of the receiver incidence and axial stagger were considered. Computational fluid dynamic simulations showed good agreement with the measurements, and these were used in the interpretation of the experimental results. The overall interference loads for a given multibody configuration were found to be a complex function of the pressure footprints from the compression and expansion waves emanating from the generator body as well as the flow pitch induced by the generator shockwave. These induced interference loads change sign as the shock impingement location moves aft over the receiver and in some cases cause the receiver body to become statically unstable. Overall, the observed interference effects can modify the subsequent body trajectories and may increase the likelihood of a collision
Misleading variations in estimated rotational frequency splittings of solar p modes: Consequences for helio- and asteroseismology
The aim of this paper is to investigate whether there are any 11-yr or
quasi-biennial solar cycle-related variations in solar rotational splitting
frequencies of low-degree solar p modes. Although no 11-yr signals were
observed, variations on a shorter timescale (~2yrs) were apparent. We show that
the variations arose from complications/artifacts associated with the
realization noise in the data and the process by which the data were analyzed.
More specifically, the realization noise was observed to have a larger effect
on the rotational splittings than accounted for by the formal uncertainties.
When used to infer the rotation profile of the Sun these variations are not
important. The outer regions of the solar interior can be constrained using
higher-degree modes. While the variations in the low-l splittings do make large
differences to the inferred rotation rate of the core, the core rotation rate
is so poorly constrained, even by low-l modes, that the different inferred
rotation profiles still agree within their respective 1sigma uncertainties. By
contrast, in asteroseismology, only low-l modes are visible and so higher-l
modes cannot be used to constrain the rotation profile of stars. Furthermore,
we usually only have one data set from which to measure the observed low-l
splitting. In such circumstances the inferred internal rotation rate of a main
sequence star could differ significantly from estimates of the surface rotation
rate, hence leading to spurious conclusions. Therefore, extreme care must be
taken when using only the splittings of low-l modes to draw conclusions about
the average internal rotation rate of a star.Comment: 10 pages, 7 figures, accepted for publication in MNRA
Common shared system model for evolvable assembly systems
A vital aspect of distributed control in an adaptable production system is coherence between each system resource. The Evolvable Assembly Systems project addresses this challenge using a common shared system model. This paper provides an overview of the project and the shared system model approach as implemented in a real world demonstration cell
Conceptual framework for ubiquitous cyber-physical assembly systems in airframe assembly
Current sectoral drivers for the manufacturing of complex products - such as airframe assembly -require new manufacturing system paradigms to meet them. In this paper, we propose a conceptual framework for cyber-physical systems driven by ubiquitous context-awareness by drawing together a unique and coherent vision that merges several extant concepts. This framework leverages recent progress in agent-based systems, exible manufacturing, ubiquitous computing, and metrology-driven robotic assembly in the Evolvable Assembly Systems project. As such, although it is adapted for and grounded in manufacturing facilities for airframe assembly, it is not specifically tailored to that application and is a much more general framework. As well as outlining our conceptual framework, we also provide a vision for assembly grounded in a review of existing research in the area
When too much entertainment is barely enough : current affairs television in the 1990s
The article examines the state of current affairs journalism and looks at news values versus entertainment values
Flicker as a tool for characterizing planets through Asterodensity Profiling
Variability in the time series brightness of a star on a timescale of 8
hours, known as 'flicker', has been previously demonstrated to serve as a proxy
for the surface gravity of a star by Bastien et al. (2013). Although surface
gravity is crucial for stellar classification, it is the mean stellar density
which is most useful when studying transiting exoplanets, due to its direct
impact on the transit light curve shape. Indeed, an accurate and independent
measure of the stellar density can be leveraged to infer subtle properties of a
transiting system, such as the companion's orbital eccentricity via
asterodensity profiling. We here calibrate flicker to the mean stellar density
of 439 Kepler targets with asteroseismology, allowing us to derive a new
empirical relation given by
. The calibration is valid for stars with
KK, and flicker estimates corresponding
to stars with . Our relation has a model error in the
stellar density of 31.7% and so has times lower precision than that
from asteroseismology but is applicable to a sample times greater.
Flicker therefore provides an empirical method to enable asterodensity
profiling on hundreds of planetary candidates from present and future missions.Comment: 6 pages, 3 figures, 1 table. Accepted to ApJ Letters. Code available
at https://www.cfa.harvard.edu/~dkipping/flicker.htm
Flow Dynamics And Plasma Heating Of Spheromaks In SSX
We report several new experimental results related to flow dynamics and heating from single dipole-trapped spheromaks and spheromak merging studies at SSX. Single spheromaks (stabilized with a pair of external coils, see Brown, Phys. Plasmas 13 102503 (2006)) and merged FRC-like configurations (see Brown, Phys. Plasmas 13, 056503 (2006)) are trapped in our prolate (R = 0.2 m, L = 0.6 m) copper flux conserver. Local spheromak flow is studied with two Mach probes (r(1) = rho(i) ) calibrated by time-of-flight with a fast set of magnetic probes at the edge of the device. Both Mach probes feature six ion collectors housed in a boron nitride sheath. The larger Mach probe will ultimately be used in the MST reversed field pinch. Line averaged flow is measured by ion Doppler spectroscopy (IDS) at the midplane. The SSX IDS instrument measures with 1 mu s or better time resolution the width and Doppler shift of the C-III impurity (H plasma) 229.7 nm line to determine the temperature and line-averaged flow velocity (see Cothran, RSI 77, 063504 (2006)). We find axial flows up to 100 km/s during formation of the dipole trapped spheromak. Flow returns at the wall to form a large vortex. Recent high-resolution IDS velocity measurements during spheromak merging show bi-directional outflow jets at +/- 40 km/s (nearly the Alfven speed). We also measure T-i \u3e= 80 eV and T-e \u3e= 20 eV during spheromak merging events after all plasma facing surfaces are cleaned with helium glow discharge conditioning. Transient electron heating is inferred from bursts on a four-channel soft x-ray array. The spheromaks are also characterized by a suite of magnetic probe arrays for magnetic structure B(r,t), and interferometry for n(e) . Finally, we are designing a new oblate, trapezoidal flux conserver for FRC studies. Equilibrium and dynamical simulations suggest that a tilt-stable, oblate FRC can be formed by spheromak merging in the new flux conserver
Book Reviews
Review of Sea Struck. By W.H. Bunting (Gardiner,Maine: Tilbury House, 2004. Pp. xvi+366.Maps, photographs, notes, index. $30.00)
Proof of principle : the adaptive geometry of social foragers
Acknowledgments We thank Cape Nature for permission to undertake the study. We thank Dr Matt Grove and two anonymous referees for comments and suggestions that improved the manuscript substantially. This research was funded by grants from the Leakey Foundation, National Science and Engineering Research Council, Canada to S.P.H. and L.B., and by the National Research Foundation, South Africa to S.P.H. His co-authors dedicate this paper to the memory of P.M.R.C. The authors declare no competing interests.Peer reviewedPostprin
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