17,338 research outputs found
Noise-Activated Escape from a Sloshing Potential Well
We treat the noise-activated escape from a one-dimensional potential well of
an overdamped particle, to which a periodic force of fixed frequency is
applied. We determine the boundary layer behavior, and the physically relevant
length scales, near the oscillating well top. We show how stochastic behavior
near the well top generalizes the behavior first determined by Kramers, in the
case without forcing. Both the case when the forcing dies away in the weak
noise limit, and the case when it does not, are examined. We also discuss the
relevance of various scaling regimes to recent optical trap experiments.Comment: 9 pages, no figures, REVTeX, expanded versio
Innovation and Efficiency
Innovation is a complex phenomenon that involves all spheres of technological, economic, and social activity, from research and development to investment, production, and application. In the management of innovation the relationship between innovation and efficiency is the key issue. In this report, therefore, we elaborate on a method for measuring efficiency in the innovation process. The core of our concept of efficiency is the link between the efficiency of the production unit that has adopted an innovation (dynamic efficiency) and the efficiency of the entire production field within which production units must act (average efficiency). The development of relative efficiency is connected to differences between basic, improvement-related, and pseudo innovations and to the decision-making environment for managers.
Factors influencing innovative activities follow a continuum of efficacy ranging from inhibiting to strongly promoting innovative activities. Looking at the innovation process from the standpoint of the innovating system, we distinguish major determinants of performance and them compare the performance of industrial organizations through a profile showing these determinants in research and development, production, and marketing and in management at all stages
Highly confined electromagnetic fields in arrays of strongly coupled Ag nanoparticles
Linear arrays of very small Ag nanoparticles (diameter ~10 nm, spacing 0–4 nm) were fabricated in sodalime glass using an ion irradiation technique. Optical extinction spectroscopy of the arrays reveals a large polarization-dependent splitting of the collective plasmon extinction band. Depending on the preparation condition, a redshift of the longitudinal resonance as large as 1.5 eV is observed. Simulations of the three-dimensional electromagnetic field evolution are used to determine the resonance energy of idealized nanoparticle arrays with different interparticle spacings and array lengths. Using these data, the experimentally observed redshift is attributed to collective plasmon coupling in touching particles and/or in long arrays of strongly coupled particles. The simulations also indicate that for closely coupled nanoparticles (1–2 nm spacing) the electromagnetic field is concentrated in nanoscale regions (10 dB radius: 3 nm) between the particles, with a 5000-fold local field intensity enhancement. In arrays of 1-nm-spaced particles the dipolar particle interaction extends to over 10 particles, while for larger spacing the interaction length decreases. Spatial images of the local field distribution in 12-particle arrays of touching particles reveal a particlelike coupled mode with a resonance at 1.8 eV and a wirelike mode at 0.4 eV
Rotating system for four-dimensional transverse rms-emittance measurements
Knowledge of the transverse four-dimensional beam rms-parameters is essential
for applications that involve lattice elements that couple the two transverse
degrees of freedom (planes). Of special interest is the removal of inter-plane
correlations to reduce the projected emittances. A dedicated ROtating System
for Emittance measurements (ROSE) has been proposed, developed, and
successfully commissioned to fully determine the four-dimensional beam matrix.
This device has been used at the High Charge injector (HLI) at GSI using a beam
line which is composed of a skew quadrupole triplet, a normal quadrupole
doublet, and ROSE. Mathematical algorithms, measurements, and results for ion
beams of 83Kr13+ at 1.4 MeV/u are reported in this paper.Comment: 11 pages, 10 figure
Twin nucleation in Fe-based bcc alloys - Modeling and experiments
We develop an analytical expression for twin nucleation stress in bcc metal and alloys considering generalized planar fault energy and the dislocations bounding the twin nucleus. We minimize the total energy to predict the twinning stress relying only on parameters that are obtained through atomistic calculations, thus excluding the need for any empirical constants. We validate the present approach by means of precise measurements of the onset of twinning in bcc Fe-50at% Cr single crystals showing excellent agreement. The experimental observations of the three activated slip systems of symmetric configuration in relation to the twinning mechanism are demonstrated via transmission electron microscopy techniques along with digital image correlation. We then confirm the validity of the model for Fe, Fe-25at% Ni and Fe-3at% V alloys compared with experiments from the literature to show general applicability
Twin migration in Fe-based bcc crystals: Theory and experiments
We establish an overall energy expression to determine the twin migration stress in bcc metals. Twin migration succeeds twin nucleation often after a load drop, and a model to establish twin migration stress is of paramount importance. We compute the planar fault energy barriers and determine the elastic energies of twinning dislocations including the role of residual dislocations (br) and twin intersection types such as 1 1 0, 1 1 3 and 2 1 0. The energy expression derived provides the twin migration stress in relation to the twin nucleation stress with a ratio of 0.5-0.8 depending on the resultant residual burgers vector and the intersection types. Utilizing digital image correlation, it was possible to differentiate the twin nucleation and twin advancement events experimentally, and transmission electron microscopy observations provided further support to the modelling efforts. Overall, the methodology developed provides an enhanced understanding of twin progression in bcc metals, and most importantly the proposed model does not rely on empirical constants. We utilize Fe-50at.%Cr in our experiments, and subsequently predict the twin migration stress for pure Fe, and Fe-3at.%V from the literature showing excellent agreement with experiments. © 2014 Taylor & Francis
Experimental Test of Momentum Cooling Model Predictions at COSY and Conclusions for WASA and HESR
The High-Energy Storage Ring (HESR) of the future International Facility for
Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an
anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An
important and challenging feature of the new facility is the combination of
highly dense phase space cooled beams with internal targets. A detailed
numerical and analytical approach to the Fokker-Planck equation for
longitudinal filter cooling including the beam - target interaction has been
carried out to demonstrate the stochastic cooling capability. To gain
confidence in the model predictions a series of experimental stochastic cooling
studies with the internal target ANKE at COSY have been carried out. A
remarkable agreement between model and experiment was achieved. On this basis
longitudinal stochastic cooling simulations were performed to predict the
possibilities and limits of cooling when the newly installed WASA Pellet-target
is operated.Comment: 17 pages, 11 figures, Talk given at Symposium on Meson Physics at
COSY-11 and WASA-at-COSY, Cracow, Poland, 17-22 Jun 200
Expected exponential loss for gaze-based video and volume ground truth annotation
Many recent machine learning approaches used in medical imaging are highly
reliant on large amounts of image and ground truth data. In the context of
object segmentation, pixel-wise annotations are extremely expensive to collect,
especially in video and 3D volumes. To reduce this annotation burden, we
propose a novel framework to allow annotators to simply observe the object to
segment and record where they have looked at with a \$200 eye gaze tracker. Our
method then estimates pixel-wise probabilities for the presence of the object
throughout the sequence from which we train a classifier in semi-supervised
setting using a novel Expected Exponential loss function. We show that our
framework provides superior performances on a wide range of medical image
settings compared to existing strategies and that our method can be combined
with current crowd-sourcing paradigms as well.Comment: 9 pages, 5 figues, MICCAI 2017 - LABELS Worksho
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