17,863 research outputs found
A wireless, real-time, social music performance system for mobile phones
The paper reports on the Cellmusic system: a real-time, wireless distributed composition and performance system designed for domestic mobile devices. During a performance, each mobile device communicates with others, and may create sonic events in a passive (non interactive) mode or may influence the output of other devices. Cellmusic distinguishes itself from other mobile phone performance environments in that it is intended for performance in ad hoc locations, with services and performances automatically and dynamically adapting to the number of devices within a given proximity. It is designed to run on a number of mobile phone platforms to allow as wider distribution as possible, again distinguishing itself from other mobile performance systems which primarily run on a single device. Rather than performances being orchestrated or managed, it is intended that users will access it and create a performance in the same manner that they use mobile phones for interacting socially at different times throughout the day. However, this does not preclude the system being used in a more traditional performance environment. This accessibility and portability make it an ideal platform for sonic artists who choose to explore a variety of physical environments (such as parks and other public spaces)
What is Sound?
(Abstract to follow
Laterally Propagating Detonations in Thin Helium Layers on Accreting White Dwarfs
Theoretical work has shown that intermediate mass (0.01Msun<M_He<0.1Msun)
Helium shells will unstably ignite on the accreting white dwarf (WD) in an AM
CVn binary. For more massive (M>0.8Msun) WDs, these helium shells can be dense
enough (5x10^5 g/cc) that the convectively burning region runs away on a
timescale comparable to the sound travel time across the shell; raising the
possibility for an explosive outcome. The nature of the explosion (i.e.
deflagration or detonation) remains ambiguous. In the case of detonation, this
causes a laterally propagating front whose properties in these geometrically
thin and low density shells we begin to study here. Our calculations show that
the radial expansion time of <0.1 s leads to incomplete helium burning, in
agreement with recent work by Sim and collaborators, but that the nuclear
energy released is still adequate to realize a self-sustaining detonation
propagating laterally at slower than the Chapman-Jouguet speed. Our simulations
resolve the subsonic region behind the front and are consistent with a direct
computation of the reaction structure from the shock strength. The ashes are
typically He rich, and consist of predominantly Ti-44, Cr-48, along with a
small amount of Fe-52, with very little Ni-56 and with significant Ca-40 in
carbon-enriched layers. If this helium detonation results in a Type Ia
Supernova, its spectral signatures would appear for the first few days after
explosion. (abridged)Comment: 7 pages, 5 figure, accepted to the Astrophysical Journa
Seismic detection of sonic booms
The pressure signals from a sonic boom will produce a small, but detectable, ground motion. The extensive seismic network in southern California, consisting of over 200 sites covering over 50 000 square kilometers, is used to map primary and secondary sonic boom carpets. Data from the network is used to analyze three supersonic overflights in the western United States. The results are compared to ray-tracing computations using a realistic model of the stratified atmospheric at the time of the measurements. The results show sonic boom ground exposure under the real atmosphere is much larger than previously expected or predicted by ray tracing alone. Finally, seismic observations are used to draw some inferences on the origin of a set of "mystery booms" recorded in 1992â1993 in southern California
FPGA-accelerated machine learning inference as a service for particle physics computing
New heterogeneous computing paradigms on dedicated hardware with increased
parallelization, such as Field Programmable Gate Arrays (FPGAs), offer exciting
solutions with large potential gains. The growing applications of machine
learning algorithms in particle physics for simulation, reconstruction, and
analysis are naturally deployed on such platforms. We demonstrate that the
acceleration of machine learning inference as a web service represents a
heterogeneous computing solution for particle physics experiments that
potentially requires minimal modification to the current computing model. As
examples, we retrain the ResNet-50 convolutional neural network to demonstrate
state-of-the-art performance for top quark jet tagging at the LHC and apply a
ResNet-50 model with transfer learning for neutrino event classification. Using
Project Brainwave by Microsoft to accelerate the ResNet-50 image classification
model, we achieve average inference times of 60 (10) milliseconds with our
experimental physics software framework using Brainwave as a cloud (edge or
on-premises) service, representing an improvement by a factor of approximately
30 (175) in model inference latency over traditional CPU inference in current
experimental hardware. A single FPGA service accessed by many CPUs achieves a
throughput of 600--700 inferences per second using an image batch of one,
comparable to large batch-size GPU throughput and significantly better than
small batch-size GPU throughput. Deployed as an edge or cloud service for the
particle physics computing model, coprocessor accelerators can have a higher
duty cycle and are potentially much more cost-effective.Comment: 16 pages, 14 figures, 2 table
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