4,080 research outputs found
Two techniques for digital filter design
Digital controllers, one using a special-purpose computer and the other using a combination of digital and analog techniques, are designed around /1/ computers that simulate the transfer function and interface with the system, and /2/ analog and digital circuits, converters, amplifiers, constant multipliers, and delay lines that form a digital filter
Phasespace Correlations of Antideuterons in Heavy Ion Collisions
In the framework of the relativistic quantum molecular dynamics approach
({\small RQMD}) we investigate antideuteron () observables in
Au+Au collisions at 10.7~AGeV. The impact parameter dependence of the formation
ratios and is calculated. In central
collisions, the antideuteron formation ratio is predicted to be two orders of
magnitude lower than the deuteron formation ratio. The yield in
central Au+Au collisions is one order of magnitude lower than in Si+Al
collisions. In semicentral collisions different configuration space
distributions of 's and 's lead to a large
``squeeze--out'' effect for antideuterons, which is not predicted for the
's
New Scaling Law for Deuteron Production in Ultra-Relativistic Nucleus Nucleus Collisions
Deuteron production in S and Pb induced collisions at beam energies of 200
and 160 AGeV is studied in the framework of the transport theoretical approach
RQMD. Strong transverse flow invalidates the differential coalescence formula
in momentum space. The transverse momentum integrated yields scale in a
broad rapidity interval with the squared proton densities and inversely with
the produced particle rapidity densities. This kind of scaling can be linked to
constant relative sizes of nucleon and pion sources at freeze-out. With
increasing projectile mass the nucleon source blows up stronger than the pion
source. As a result, the scaled deuteron densities drop in central Pb+Pb
collisions by 15 percent as compared to S induced reactions.Comment: 12 pages + 4 postscript figures (uuencoded and included
An Automatic Cloud Tracking System Based on the Cross-Covariance Method
An automatic cloud tracking system based on the computation of the cross-covariance between satellite images has been developed. The six steps of the System for Automatic Wind Extraction from Geostationary Satellite-Data SAWEGS are preprocessing, cloud tracking, height assignment, earth location, wind vector computation, and quality control. The system embodies various unique aspects developed to address the problems encountered with an automated technique in general and this technique in particular. These aspects include histogram-based temperature slicing, cloud edge and surface enhancement, tracking trackability tests, and use of numerical analysis temperature profiles for height assignment. Examples of applying SAWEGS to visible data, to infrared data, and to a difficult tropical cyclone case show the good quality and coverage of resulting vectors as well as the remaining difficulties.PE 62759NPN 9F5255179NEPRF WU 6.2-1
Dimers on two-dimensional lattices
We consider close-packed dimers, or perfect matchings, on two-dimensional
regular lattices. We review known results and derive new expressions for the
free energy, entropy, and the molecular freedom of dimers for a number of
lattices including the simple-quartic (4^4), honeycomb (6^3), triangular (3^6),
kagome (3.6.3.6), 3-12 (3.12^2) and its dual [3.12^2], and 4-8 (4.8^2) and its
dual Union Jack [4.8^2] Archimedean tilings. The occurrence and nature of phase
transitions are also analyzed and discussed.Comment: Typos corrections in Eqs. (28), (32) and (43
A Nuclear Physics Program at the ATLAS Experiment at the CERN Large Hadron Collider
The ATLAS collaboration has significant interest in the physics of
ultra-relativistic heavy ion collisions. We submitted a Letter of Intent to the
United States Department of Energy in March 2002. The following document is a
slightly modified version of that LOI. More details are available at:
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/SM/ionsComment: Letter of Intent submitted to the United States Department of Energy
Nuclear Physics Division in March 2002 (revised version
Magnetization dynamics in dysprosium orthoferrites via inverse Faraday effect
The ultrafast non-thermal control of magnetization has recently become
feasible in canted antiferromagnets through photomagnetic instantaneous pulses
[A.V. Kimel {\it et al.}, Nature {\bf 435}, 655 (2005)]. In this experiment
circularly polarized femtosecond laser pulses set up a strong magnetic field
along the wave vector of the radiation through the inverse Faraday effect,
thereby exciting non-thermally the spin dynamics of dysprosium orthoferrites. A
theoretical study is performed by using a model for orthoferrites based on a
general form of free energy whose parameters are extracted from experimental
measurements. The magnetization dynamics is described by solving coupled
sublattice Landau-Lifshitz-Gilbert equations whose damping term is associated
with the scattering rate due to magnon-magnon interaction. Due to the inverse
Faraday effect and the non-thermal excitation, the effect of the laser is
simulated by magnetic field Gaussian pulses with temporal width of the order of
hundred femtoseconds. When the field is along the z-axis, a single resonance
mode of the magnetization is excited. The amplitude of the magnetization and
out-of-phase behavior of the oscillations for fields in z and -z directions are
in good agreement with the cited experiment. The analysis of the effect of the
temperature shows that magnon-magnon scattering mechanism affects the decay of
the oscillations on the picosecond scale. Finally, when the field pulse is
along the x-axis, another mode is excited, as observed in experiments. In this
case the comparison between theoretical and experimental results shows some
discrepancies whose origin is related to the role played by anisotropies in
orthoferrites.Comment: 10 pages, 6 figure
Going concern modifications and the self-fulfilling prophecy: evidence from extreme market conditions
Purpose: This study aims to examine whether two periods of extreme market conditions – the governance crisis and Sarbanes-Oxley Act regulatory shock of 2002 and the 2007–2008 global financial crisis – incrementally impacted the self-fulfilling prophecy effect, by examining the propensity of US firms receiving going concern modification (GCM) opinions to go bankrupt relative to their non-GCM distress risk-matched counterparts during these two crisis periods. Design/methodology/approach: To assess the potential influence of the governance/regulatory shock of 2002 and the global financial crisis moderate or mitigate the self-fulfilling prophecy effect, the authors use multivariate logit analysis, regressing t + 1 bankruptcy status on time t GCM and other bankruptcy determinants, interacting crisis period dummies with the GCM variable. Findings: GCM firms were more likely to declare bankruptcy than their distressed non-GCM counterparts, confirming prior research documenting the existence of a self-fulfilling prophecy effect. The authors also find that the self-fulfilling prophecy effect was exacerbated by the governance crisis/Sarbanes-Oxley Act regulatory shock, but not the global financial crisis, a financial/banking sector shock. Originality/value: This study contributes to the financial crisis and auditing literatures by examining whether exogenous shocks exacerbate the self-fulfilling prophecy effect. The present analysis and findings have implications for future academic research related to systemic shocks and for auditors in documenting the inducement effect arising from the issuance of GCMs during crisis periods
Development of a posture detector using a flex sensor
In this digital age, many people spend hours every day looking at their cell phones and computers. Overuse of these devices can result in users\u27 posture deterioration. Poor postures not only detract from a person\u27s appearance but can also lead to chronic back discomfort and inflammation. Even though everyone knows the detrimental effects of poor postures, it is difficult for them to correct their bad habits. This is because poor postures are gradually developed, and they are usually related to a person\u27s lifestyle. The purpose of this project was to embed a poor posture detector (a posture coach) into clothing so that users could wear it unobtrusively and comfortably. Its functions were to detect and alert users of poor postures, to help the users maintain proper postures continuously, and to help users correct their habits related to bad postures
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