1,039 research outputs found
Time-frequency analysis of ship wave patterns in shallow water: modelling and experiments
A spectrogram of a ship wake is a heat map that visualises the time-dependent
frequency spectrum of surface height measurements taken at a single point as
the ship travels by. Spectrograms are easy to compute and, if properly
interpreted, have the potential to provide crucial information about various
properties of the ship in question. Here we use geometrical arguments and
analysis of an idealised mathematical model to identify features of
spectrograms, concentrating on the effects of a finite-depth channel. Our
results depend heavily on whether the flow regime is subcritical or
supercritical. To support our theoretical predictions, we compare with data
taken from experiments we conducted in a model test basin using a variety of
realistic ship hulls. Finally, we note that vessels with a high aspect ratio
appear to produce spectrogram data that contains periodic patterns. We can
reproduce this behaviour in our mathematical model by using a so-called
two-point wavemaker. These results highlight the role of wave interference
effects in spectrograms of ship wakes.Comment: 14 pages, 7 figure
Observation of VH and VVH cosmic rays with an ionization-Cerenkov detector system
Heavy and ultraheavy nuclei observations of cosmic rays using ionization chamber-Cerenkov counter syste
Large area pulse ionization chamber for measurement of extremely heavy cosmic rays
Parallel plate ionization chamber for identifying relativistic cosmic ray nucle
The Isotopic Composition of Cosmic Ray Nuclei Beyond the Iron Peak
Isotope measurements of cosmic ray nuclei beyond the Fe peak are considered, using the charge region from Z=29 to Z∼40 as an example. Such studies can address a number of important questions that bear on cosmic ray origin, acceleration, and propagation. One possible approach for measuring isotopes with Z≥30 is based on large‐area arrays of silicon solid state detectors combined with scintillating optical fiber trajectory detectors optical fiber trajectory detectors
The SUPERTIGER Instrument: Measurement of Elemental Abundances of Ultra-Heavy Galactic Cosmic Rays
The SuperTIGER (Super Trans-Iron Galactic Element Recorder) instrument was developed to measure the abundances of galactic cosmic-ray elements from _(10)Ne to _(40)Zr with individual element resolution and the high statistics needed to test models of cosmic-ray origins. SuperTIGER also makes exploratory measurements of the
abundances of elements with 40 29 and ∼60 with Z >49. Here, we describe the instrument, the methods of charge identification employed, the SuperTIGER balloon flight, and the instrument performance
The Need for Sensemaking in Networked Privacy and Algorithmic Responsibility
This paper proposes that two significant and emerging problems facing our connected, data-driven
society may be more effectively solved by being framed as sensemaking challenges. The first is in
empowering individuals to take control of their privacy, in device-rich information environments
where personal information is fed transparently to complex networks of information brokers. Although
sensemaking is often framed as an analytical activity undertaken by experts, due to the fact that
non-specialist end-users are now being forced to make expert-like decisions in complex information
environments, we argue that it is both appropriate and important to consider sensemaking challenges
in this context. The second is in supporting human-in-the-loop algorithmic decision-making, in which
important decisions bringing direct consequences for individuals, or indirect consequences for groups,
are made with the support of data-driven algorithmic systems. In both privacy and algorithmic decision-making, framing the problems as sensemaking challenges acknowledges complex and illdefined
problem structures, and affords the opportunity to view these activities as both building up
relevant expertise schemas over time, and being driven potentially by recognition-primed decision
making
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