2,596 research outputs found
COMPOSITIONAL EXPLORATIONS OF PLASTIC SOUND
Each piece of music in this research is meant to explore a different aspect
of music as a plastic art. Conclusions reached in the review of each new work
were used to guide the development of the next.
The notions of plasticity in sound, and sound as a plastic material were
used to give the overall research a focal point. In exploring different types of
composition, reciprocal plasticity between the materials and the developing
ideas of the music are discussed in the context of ecological and biological
psychology.
By restricting all these works within the genre of 'plastic arts' it became
necessary to introduce a new technique for instrumental composition. An
aural model is used to replace the traditional written score. These instrumental
works were developed entirely within an auditory situation.Funded by De Montfort Universit
Snake: a Stochastic Proximal Gradient Algorithm for Regularized Problems over Large Graphs
A regularized optimization problem over a large unstructured graph is
studied, where the regularization term is tied to the graph geometry. Typical
regularization examples include the total variation and the Laplacian
regularizations over the graph. When applying the proximal gradient algorithm
to solve this problem, there exist quite affordable methods to implement the
proximity operator (backward step) in the special case where the graph is a
simple path without loops. In this paper, an algorithm, referred to as "Snake",
is proposed to solve such regularized problems over general graphs, by taking
benefit of these fast methods. The algorithm consists in properly selecting
random simple paths in the graph and performing the proximal gradient algorithm
over these simple paths. This algorithm is an instance of a new general
stochastic proximal gradient algorithm, whose convergence is proven.
Applications to trend filtering and graph inpainting are provided among others.
Numerical experiments are conducted over large graphs
You shall not pass: Mitigating SQL Injection Attacks on Legacy Web Applications
SQL injection (SQLi) attacks pose a significant threat to the security of web
applications. Existing approaches do not support object-oriented programming
that renders these approaches unable to protect the real-world web apps such as
Wordpress, Joomla, or Drupal against SQLi attacks. We propose a novel hybrid
static-dynamic analysis for PHP web applications that limits each PHP function
for accessing the database. Our tool, SQLBlock, reduces the attack surface of
the vulnerable PHP functions in a web application to a set of query descriptors
that demonstrate the benign functionality of the PHP function. We implement
SQLBlock as a plugin for MySQL and PHP. Our approach does not require any
modification to the web app. W evaluate SQLBlock on 11 SQLi vulnerabilities in
Wordpress, Joomla, Drupal, Magento, and their plugins. We demonstrate that
SQLBlock successfully prevents all 11 SQLi exploits with negligible performance
overhead (i.e., a maximum of 3% on a heavily-loaded web server)Comment: Accepted in ASIACCS 202
Measuring glacier surface roughness using plot-scale, close-range digital photogrammetry
Glacier roughness at sub-metre scales is an important control on the ice surface energy balance and has implications for scattering energy measured by remote-sensing instruments. Ice surface roughness is dynamic as a consequence of spatial and temporal variation in ablation. To date, studies relying on singular and/or spatially discrete two-dimensional profiles to describe ice surface roughness have failed to resolve common patterns or causes of variation in glacier surface morphology. Here we demonstrate the potential of close-range digital photogrammetry as a rapid and cost-effective method to retrieve three-dimensional data detailing plot-scale supraglacial topography. The photogrammetric approach here employed a calibrated, consumer-grade 5 Mpix digital camera repeatedly imaging a plot-scale (≤25 m2) ice surface area on Midtre Lovénbreen, Svalbard. From stereo-pair images, digital surface models (DSMs) with sub-centimetre horizontal resolution and 3 mm vertical precision were achieved at plot scales ≤4 m2. Extraction of roughness metrics including estimates of aerodynamic roughness length (z 0) was readily achievable, and temporal variations in the glacier surface topography were captured. Close-range photogrammetry, with appropriate camera calibration and image acquisition geometry, is shown to be a robust method to record sub-centimetre variations in ablating ice topography. While the DSM plot area may be limited through use of stereo-pair images and issues of obliquity, emerging photogrammetric packages are likely to overcome such limitations
Black holes and information theory
During the past three decades investigators have unveiled a number of deep
connections between physical information and black holes whose consequences for
ordinary systems go beyond what has been deduced purely from the axioms of
information theory. After a self-contained introduction to black hole
thermodynamics, we review from its vantage point topics such as the information
conundrum that emerges from the ability of incipient black holes to radiate,
the various entropy bounds for non-black hole systems (holographic bound,
universal entropy bound, etc) which are most easily derived from black hole
thermodynamics, Bousso's covariant entropy bound, the holographic principle of
particle physics, and the subject of channel capacity of quantum communication
channels.Comment: RevTeX, 12 pages, 5 figures. To appear in Contemporary Physic
Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope
The ANTARES collaboration has performed a series of {\em in situ}
measurements to study the background light for a planned undersea neutrino
telescope. Such background can be caused by K decays or by biological
activity. We report on measurements at two sites in the Mediterranean Sea at
depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were
used to measure single counting rates and coincidence rates for pairs of tubes
at various distances. The background rate is seen to consist of three
components: a constant rate due to K decays, a continuum rate that
varies on a time scale of several hours simultaneously over distances up to at
least 40~m, and random bursts a few seconds long that are only correlated in
time over distances of the order of a meter. A trigger requiring coincidences
between nearby photomultiplier tubes should reduce the trigger rate for a
neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle
Physic
Measuring glacier surface roughness using plot-scale, close-range digital photogrammetry
Glacier roughness at sub-metre scales is an important control on the ice surface energy balance and has implications for scattering energy measured by remote-sensing instruments. Ice surface roughness is dynamic as a consequence of spatial and temporal variation in ablation. To date, studies relying on singular and/or spatially discrete two-dimensional profiles to describe ice surface roughness have failed to resolve common patterns or causes of variation in glacier surface morphology. Here we demonstrate the potential of close-range digital photogrammetry as a rapid and cost-effective method to retrieve three-dimensional data detailing plot-scale supraglacial topography. The photogrammetric approach here employed a calibrated, consumer-grade 5 Mpix digital camera repeatedly imaging a plotscale (≤25m2) ice surface area on Midtre Lovénbreen, Svalbard. From stereo-pair images, digital surface models (DSMs) with sub-centimetre horizontal resolution and 3mm vertical precision were achieved at plot scales ≤4m2. Extraction of roughness metrics including estimates of aerodynamic roughness length (z0) was readily achievable, and temporal variations in the glacier surface topography were captured. Close-range photogrammetry, with appropriate camera calibration and image acquisition geometry, is shown to be a robust method to record sub-centimetre variations in ablating ice topography. While the DSM plot area may be limited through use of stereo-pair images and issues of obliquity, emerging photogrammetric packages are likely to overcome such limitations
Scientific progress despite irreproducibility: A seeming paradox
It appears paradoxical that science is producing outstanding new results and
theories at a rapid rate at the same time that researchers are identifying
serious problems in the practice of science that cause many reports to be
irreproducible and invalid. Certainly the practice of science needs to be
improved and scientists are now pursuing this goal. However, in this
perspective we argue that this seeming paradox is not new, has always been part
of the way science works, and likely will remain so. We first introduce the
paradox. We then review a wide range of challenges that appear to make
scientific success difficult. Next, we describe the factors that make science
work-in the past, present, and presumably also in the future. We then suggest
that remedies for the present practice of science need to be applied
selectively so as not to slow progress, and illustrate with a few examples. We
conclude with arguments that communication of science needs to emphasize not
just problems but the enormous successes and benefits that science has brought
and is now bringing to all elements of modern society.Comment: 3 figure
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