65,566 research outputs found
The impact of water on free-falling bodies
Report discussed measures to cushion impact on body falling into water. Heavy loads are generated by impact and by pressures of water cavity collapsing onto the body
Using visualization for visualization : an ecological interface design approach to inputting data
Visualization is experiencing growing use by a diverse community, with continuing improvements in the availability and usability of systems. In spite of these developments the problem of how first to get the data in has received scant attention: the established approach of pre-defined readers and programming aids has changed little in the last two decades. This paper proposes a novel way of inputting data for scientific visualization that employs rapid interaction and visual feedback in order to understand how the data is stored. The approach draws on ideas from the discipline of ecological interface design to extract and control important parameters describing the data, at the same time harnessing our innate human ability to recognize patterns. Crucially, the emphasis is on file format discovery rather than file format description, so the method can therefore still work when nothing is known initially of how the file was originally written, as is often the case with legacy binary data. © 2013 Elsevier Ltd
Modeling river delta formation
A new model to simulate the time evolution of river delta formation process
is presented. It is based on the continuity equation for water and sediment
flow and a phenomenological sedimentation/ erosion law. Different delta types
are reproduced using different parameters and erosion rules. The structures of
the calculated patterns are analyzed in space and time and compared with real
data patterns. Furthermore our model is capable to simulate the rich dynamics
related to the switching of the mouth of the river delta. The simulation
results are then compared with geological records for the Mississippi river
A human factors approach to range scheduling for satellite control
Range scheduling for satellite control presents a classical problem: supervisory control of a large-scale dynamic system, with unwieldy amounts of interrelated data used as inputs to the decision process. Increased automation of the task, with the appropriate human-computer interface, is highly desirable. The development and user evaluation of a semi-automated network range scheduling system is described. The system incorporates a synergistic human-computer interface consisting of a large screen color display, voice input/output, a 'sonic pen' pointing device, a touchscreen color CRT, and a standard keyboard. From a human factors standpoint, this development represents the first major improvement in almost 30 years to the satellite control network scheduling task
Geographic and Seasonal Distributions of CO Transport Pathways and Their Roles in Determining CO Centers in the Upper Troposphere
Past studies have identified a variety of pathways by which carbon monoxide (CO) may be transported from the surface to the tropical upper troposphere (UT); however, the relative roles that these transport pathways play in determining the distribution and seasonality of CO in the tropical UT remain unclear. We have developed a method to automate the identification of two pathways ('local convection' and 'advection within the lower troposphere (LT) followed by convective vertical transport') involved in CO transport from the surface to the UT. This method is based on the joint application of instantaneous along-track, co-located, A-Train satellite measurements. Using this method, we find that the locations and seasonality of the UT CO maxima in the tropics were strongly correlated with the frequency of local convective transport during 2007. We also find that the 'local convection' pathway (convective transport that occurred within a fire region) typically transported significantly more CO to the UT than the 'LT advection -> convection' pathway (advection of CO within the LT from a fire region to a convective region prior to convective transport). To leading order, the seasonality of CO concentrations in the tropical UT reflected the seasonality of the 'local convection' transport pathway during 2007. The UT CO maxima occurred over Central Africa during boreal spring and over South America during austral spring. Occurrence of the 'local convection' transport pathway in these two regions also peaked during these seasons. During boreal winter and summer, surface CO emission and convection were located in opposite hemispheres, which limited the effectiveness of transport to the UT. During these seasons, CO transport from the surface to the UT typically occurred via the 'LT advection -> convection' pathway.NASA Aura Science Team NNX09AD85GJackson School of Geosciences at the University of Texas at AustinNASA Jet Propulsion Laboratory at the California Institute of TechnologyGeological Science
Shaping an ultracold atomic soliton in a travelling wave laser beam
An ultracold wave packet of bosonic atoms loaded into a travelling laser wave
may form a many-atom soliton.This is disturbed by a homogeneous force field,
for example by the inevitable gravitation. The wave packet is accelerated and
therefore the laser frequency appears to be chirped in the rest frame of the
atoms. We derive the effective nonlinear Schr\"odinger equation. It shows a
time dependent nonlinearity coefficient which amounts to a damping or
antidamping, respectively. The accelerated packet solution remains a soliton
which changes its shape adiabatically. Similarly, an active shaping can be
obtained in the force-free case by chirping the laser frequency thus
representing a way of coherent control of the soliton form. The experimental
consequences are discussed.Comment: 5 pages, Latex, to published in Europhys. Let
Remodelling sheltered housing and residential care homes to extra care housing: advice to housing and care providers
Quantum state transfer between a Bose-Einstein condensate and an optomechanical mirror
In this paper we describe a scheme for state transfer between a trapped
atomic Bose condensate and an optomechanical end-mirror mediated by a cavity
field. Coupling between the mirror and the cold gas arises from the fact that
the cavity field can produce density oscillations in the gas which in turn acts
as an internal Bragg mirror for the field. After adiabatic elimination of the
cavity field we find that the hybrid system of the gas and mirror is described
by a beam splitter Hamiltonian that allows for state transfer, but only if the
quantum nature of the cavity field is retained
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