Search results for "Second moment of area"
showing 10 items of 18 documents
Scaling behavior of an airplane-boarding model
2013
An airplane-boarding model, introduced earlier by Frette and Hemmer [Phys. Rev. E 85, 011130 (2012)], is studied with the aim of determining precisely its asymptotic power-law scaling behavior for a large number of passengers $N$. Based on Monte Carlo simulation data for very large system sizes up to $N={2}^{16}=65\phantom{\rule{0.16em}{0ex}}536$, we have analyzed numerically the scaling behavior of the mean boarding time $\ensuremath{\langle}{t}_{b}\ensuremath{\rangle}$ and other related quantities. In analogy with critical phenomena, we have used appropriate scaling Ans\"atze, which include the leading term as some power of $N$ (e.g., $\ensuremath{\propto}$${N}^{\ensuremath{\alpha}}$ for …
The structure and phase transition of mixed crystals
1996
The phase transition and molecular motions of methylammonium cations are studied in the temperature range from 110 to 450 K in the (x = 0.22, 0.345) (MACAB) crystal by x-ray DSC, dilatometric, dielectric and NMR techniques. It is shown that MACAB (x = 0.22) undergoes a structural phase transition at 222 K. The second moment of the NMR line () and the temperature dependence of spin lattice relaxation time () results are interpreted in terms of ( ion dynamics. In the high-temperature phase (I) the cations undergo isotropic reorientations. In the low-temperature phase (II) only one of three cations is still disordered, whereas the two others perform a type of reorientation about their C - N ax…
1H NMR study of dynamical inequivalence of cations in [C(NH2)3]3Sb2Cl9
2001
Abstract The proton NMR second moment and spin–lattice relaxation time have been studied for polycrystalline tris-guanidinium nonachlorodiantimonate(III) in a wide temperature range. The C 3 reorientation of two types of the cations, hindered by very different potential barriers (20.5 and 54.5 kJ/mol) has been revealed. An unusually large dynamical inequivalence of two cations evidently reflects their different crystalline environments.
Ensemble properties of securities traded in the NASDAQ market
2001
We study the price dynamics of stocks traded in the NASDAQ market by considering the statistical properties of an ensemble of stocks traded simultaneously. For each trading day of our database, we study the ensemble return distribution by extracting its first two central moments. According to previous results obtained for the NYSE market, we find that the second moment is a long-range correlated variable. We compare time-averaged and ensemble-averaged price returns and we show that the two averaging procedures lead to different statistical results.
Parameter Uncertainty in Shallow Rainfall-triggered Landslide Modeling at Basin Scale: A Probabilistic Approach
2014
Abstract This study proposes a methodology to account for the uncertainty of hydrological and mechanical parameters in coupled distributed hydrological-stability models for shallow landslide assessment. A probabilistic approach was implemented in an existing eco-hydrological and landslide model by randomizing soil cohesion, friction angle and soil retention parameters. The model estimates the probability of failure through an assumed theoretical Factor of Safety (FS) distribution, conditioned on soil moisture content. The time-dependent and spatially distributed FS statistics are approximated by the First Order Second Moment (FOSM) method. The model was applied to the Rio Mameyes Basin, loc…
Iterative closure method for non-linear systems driven by polynomials of Gaussian filtered processes
2008
This paper concerns the statistical characterization of the non-Gaussian response of non-linear systems excited by polynomial forms of filtered Gaussian processes. The non-Gaussianity requires the computation of moments of any order. The problem is solved profiting from both the stochastic equivalent linearization (EL), and the moment equation approach of Ito's stochastic differential calculus through a procedure divided into two parts. The first step requires the linearization of the system, while retaining the non-linear excitation; the response statistical moments are calculated exactly, and constitute a first estimate of the moments of the actual non-linear system. In the second step, t…
Elastic wave propagation in bone in vivo: methodology.
1995
The purpose of this study was to investigate the usefulness of elastic wave propagation (EWP) in estimating the mechanical properties (elasticity) of human tibia. The test group was composed of 78-yr-old women assigned to high (n = 19) and low (n = 17) bone mineral density (BMD) groups as measured at the calcaneus by the 125I-photon absorption method. The EWP apparatus consisted of an impact-producing hammer with a force strain gauge and two accelerometers positioned on the bone. Results for nylon and acrylic were used to calibrate the apparatus. Polyvinyl chloride (PVC) solid rods and tubes of various diameters were used to evaluate the relationship between the elastic wave velocity and cr…
Local moment problem
2014
The work is devoted to the local moment problem, which consists in finding of non-decreasing functions on the real axis having given first 2n + 1, n ≥ 0, power moments on the whole axis and also 2m + 1 first power moments on a certain finite axis interval. Considering the local moment problem as a combination of the Hausdorff and Hamburger truncated moment problems we obtain the conditions of its solvability and describe the class of its solutions with minimal number of growth points if the problem is solvable. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)
The impact of ocean acidification and warming on the skeletal mechanical properties of the sea urchin Paracentrotus lividus from laboratory and field…
2016
Increased atmospheric CO2 concentration is leading to changes in the carbonate chemistry and the temperature of the ocean. The impact of these processes on marine organisms will depend on their ability to cope with those changes, particularly the maintenance of calcium carbonate structures. Both a laboratory experiment (long-term exposure to decreased pH and increased temperature) and collections of individuals from natural environments characterized by low pH levels (individuals from intertidal pools and around a CO2 seep) were here coupled to comprehensively study the impact of near-future conditions of pH and temperature on the mechanical properties of the skeleton of the euechinoid sea …
Force-clamp spectroscopy of reversible bond breakage.
2008
We consider reversible breaking of adhesion bonds or folding of proteins under the influence of a constant external force. We discuss the stochastic properties of the unbinding/rebinding events and analyze their mean number and their variance in the framework of simple two-state models. In the calculations, we exploit the analogy to single molecule fluorescence and particularly between unbinding/rebinding and photon emission events. Environmental fluctuation models are used to describe deviations from Markovian behavior. The second moment of the event-number distribution is found to be very sensitive to possible exchange processes and can thus be used to identify temporal fluctuations of th…