32,258 research outputs found
Computer program for optical systems ray tracing
Program traces rays of light through optical systems consisting of up to 65 different optical surfaces and computes the aberrations. For design purposes, paraxial tracings with astigmation and third order tracings are provided
Dominance in the Monty Hall Problem
Elementary decision-theoretic analysis of the Monty Hall dilemma shows that
the problem has dominance. This makes possible to discard nonswitching
strategies, without making any assumptions on the prior distribution of factors
out of control of the decision maker. A path to the Bayesian and the minimax
decision-making environments is then straightforward.Comment: http://www.springerlink.com/content/8402812734520774/fulltext.pd
A discussion of the scaling effect in numerical simulation of the extrusion process
The main objective of the work of this paper is to study the possibility of using a small scale geometrical model in the numerical simulation of aluminium extrusion. The advantages and shortcomings of the application of the
geometrically similar model in FEM simulation are discussed. Thermal – mechanical and metallurgical combined
simulations are performed within two tests using geometrically similar models and assessment is made in terms of mechanical and material properties. It was found that small scale simulation could not reproduce most of the
important forming parameters of the original process, although it could help to bring about significant savings in
computation time
Field Driven Thermostated System : A Non-Linear Multi-Baker Map
In this paper, we discuss a simple model for a field driven, thermostated
random walk that is constructed by a suitable generalization of a multi-baker
map. The map is a usual multi-baker, but perturbed by a thermostated external
field that has many of the properties of the fields used in systems with
Gaussian thermostats. For small values of the driving field, the map is
hyperbolic and has a unique SRB measure that we solve analytically to first
order in the field parameter. We then compute the positive and negative
Lyapunov exponents to second order and discuss their relation to the transport
properties. For higher values of the parameter, this system becomes
non-hyperbolic and posseses an attractive fixed point.Comment: 6 pages + 5 figures, to appear in Phys. Rev.
Microgravity nucleation and particle coagulation experiments support
A preliminary model for diffusion between concentric hemispheres was adapted to the cylindrical geometry of a microgravity nucleation apparatus, and extended to include the effects of radiation and conduction through the containment walls. Computer programs were developed to calculate first the temperature distribution and then the evolving concentration field using a finite difference formulation of the transient diffusion and radiation processes. The following estimations are made: (1) it takes approximately 35 minutes to establish a steady temperature field; (2) magnesium vapors released into the argon environment at the steady temperature distribution will reach a maximum supersaturation ratio of approximately 10,000 in the 20-second period at a distance of 15 cm from the source of vapors; and (3) approximately 750W electrical power will be required to maintain steady operating temperatures within the chamber
OpenForensics:a digital forensics GPU pattern matching approach for the 21st century
Pattern matching is a crucial component employed in many digital forensic (DF) analysis techniques, such as file-carving. The capacity of storage available on modern consumer devices has increased substantially in the past century, making pattern matching approaches of current generation DF tools increasingly ineffective in performing timely analyses on data seized in a DF investigation. As pattern matching is a trivally parallelisable problem, general purpose programming on graphic processing units (GPGPU) is a natural fit for this problem. This paper presents a pattern matching framework - OpenForensics - that demonstrates substantial performance improvements from the use of modern parallelisable algorithms and graphic processing units (GPUs) to search for patterns within forensic images and local storage devices
Sound Source Localization in a Multipath Environment Using Convolutional Neural Networks
The propagation of sound in a shallow water environment is characterized by
boundary reflections from the sea surface and sea floor. These reflections
result in multiple (indirect) sound propagation paths, which can degrade the
performance of passive sound source localization methods. This paper proposes
the use of convolutional neural networks (CNNs) for the localization of sources
of broadband acoustic radiated noise (such as motor vessels) in shallow water
multipath environments. It is shown that CNNs operating on cepstrogram and
generalized cross-correlogram inputs are able to more reliably estimate the
instantaneous range and bearing of transiting motor vessels when the source
localization performance of conventional passive ranging methods is degraded.
The ensuing improvement in source localization performance is demonstrated
using real data collected during an at-sea experiment.Comment: 5 pages, 5 figures, Final draft of paper submitted to 2018 IEEE
International Conference on Acoustics, Speech and Signal Processing (ICASSP)
15-20 April 2018 in Calgary, Alberta, Canada. arXiv admin note: text overlap
with arXiv:1612.0350
- …