Search results for "extrapolation"

NUMERICAL ALGORITHMS

2013

For many systems of differential equations modeling problems in science and engineering, there are natural splittings of the right hand side into two parts, one non-stiff or mildly stiff, and the other one stiff. For such systems implicit-explicit (IMEX) integration combines an explicit scheme for the non-stiff part with an implicit scheme for the stiff part. In a recent series of papers two of the authors (Sandu and Zhang) have developed IMEX GLMs, a family of implicit-explicit schemes based on general linear methods. It has been shown that, due to their high stage order, IMEX GLMs require no additional coupling order conditions, and are not marred by order reduction. This work develops a …

Evaluation of methods of interpolation-extrapolation of g L (r) and F(r,θ) for high-energy brachytherapy sources

2009

Time-series analyses of species richness and relative abundances at the local scale: some methodological advices to secure the relevance of interpret…

2020

Force-velocity profiling in athletes: Reliability and agreement across methods

2021

The aim of the study was to examine the test-retest reliability and agreement across methods for assessing individual force-velocity (FV) profiles of the lower limbs in athletes. Using a multicenter approach, 27 male athletes completed all measurements for the main analysis, with up to 82 male and female athletes on some measurements. The athletes were tested twice before and twice after a 2- to 6-month period of regular training and sport participation. The double testing sessions were separated by ~1 week. Individual FV-profiles were acquired from incremental loading protocols in squat jump (SJ), countermovement jump (CMJ) and leg press. A force plate, linear encoder and a flight time cal…

Shelled-Molluscs Fauna at Abrolhos Bank (Brazil): Assessment of Both Total Species Richness and the Completed Distribution of Species Frequencies by …

2020

Numerous anthropogenic threats to the exceptionally rich coral-reef ecosystem at Abrolhos Bank (Brazil) arguably require implementing drastic conservation policy and meanwhile, urge for the prior detailed assessment of species richness and the species distribution across the Bank. Due to their unavoidable incompleteness, the already implemented “Rapid Assessment Surveys” at Abrolhos Bank deserve being completed, at least numerically, by implementing an appropriate extrapolation procedure, to avoid serious bias precisely due to ignoring both the number and the frequency distribution of those species still remaining undetected after Rapid Assessment Surveys. Complying with this concern, I rep…

The depolarization field effect on the thin ferroelectric films properties

2002

Abstract The calculation of the spontaneous polarization (Ps), dielectric susceptibility (χ) and pyroelectric coefficient (Π) of the ferroelectric films has been performed in the phenomenological theory framework. Euler–Lagrange equation was solved analytically under the boundary conditions with different extrapolation lengths at two surfaces, respectively. The depolarization field contribution was taken into account in the model of short-circuited mono domain ferroelectric film, treated as perfect insulator. The detailed analysis of the aforementioned quantities’ space distribution and their average values in two cases with and without depolarization field was carried out. It was shown tha…

3d

1999

We have measured the lifetime of the metastable 3D 5/2 level in Ca+ using the “quantum jump" technique on a single stored and laser cooled ion in a linear Paul trap. We found a linear dependence of the measured decay rate on the power of the laser which repumps the ions from the long lived 3D 3/2 level. This can be explained by off-resonant depletion of the 3D 5/2 level. The proper lifetime of this level is obtained by a linear extrapolation of the measured lifetime to zero laser power. We obtain 1100(18) ms in agreement with theoretical calculations. The observed systematic change of the decay rate resolves discrepancies between earlier experiments in which this effect had not been conside…

Lifetime and collisional depopulation of the metastable 5D 3/2-state of Yb+

1988

The lifetime and collisional depopulation rates of the metastable 5D 3/2 state of Yb+ have been determined in a radiofrequency ion trap by observation of the fluorescence count rate after ion excitation by a short laser pulse. From measurements using He, N2 and H2 as buffer gases between 10−8 and 10−6 mbar pressure and linear extrapolation to zero pressure we obtain a lifetime of τ=52.15±1.00 ms and rate constants ofR(H2)=(1.02±0.10)×10−9 cm3/s andR(N2)=(1.78±0.19)×10−10 cm3/s. The lifetime is in fair agreement with a calculated value of 74 ms.

High resolution in currents reconstruction applying the extrapolation matrix and spectrum replies

2007

A faster method for the reconstruction of currents has been proposed. For this a new algorithm has been used which extrapolates a 2D signal in less time than the iterative method of Papoulis. Results exposed in this paper show the likeness of the reconstructed currents with the new algorithm with those of the iterative method and the improvement that might be obtained in these new currents with regard to the iterative one. Furthermore, results show the higher speed of the new matrix method.

Assessing the role of evidence of mechanisms in causal extrapolation

2020

Extrapolation of causal claims from study populations to other populations of interest is a problematic issue. The standard approach in experimental research, which prioritises randomized controlled trials and statistical evidence, is not devoid of difficulties. Granted that, it has been defended that evidence of mechanisms is indispensable for causal extrapolation. We argue, contrarily, that this sort of evidence is not indispensable. Nonetheless, we also think that occasionally it may be helpful. In order to clarify its relevance, we introduce a distinction between a positive and a negative role of evidence of mechanisms. Our conclusion is that the former is highly questionable, but the l…