Design of a pistonphone

A harmonic pressure generator is developed based on the principle of plane sound waves. The pressure is generated in a cylindrical enclosure by a piston with a flat bottom; the piston is driven by a coil situated in a radial magnetic field. The coil is supplied with an alternating current; the corresponding amplitudes of the piston are measured by a precision accelerometer mounted inside the hollow piston. The apparatus was designed to calibrate the probe microphone described in [1] over a frequency range from 50 to 4000 Hz, with an accuracy of a few percent.     

Inference of ICF implosion core mix using experimental dataand theoretical mix modeling

The mixing between fuel and shell materials in Inertial Confinement Fusion (ICF) implosion cores is a current topic of interest. The goal of this work was to design direct drive ICF experiments which have varying levels of mix, and subsequently to extract information on mixing directly from the experimental data using spectroscopic techniques. The experimental design was accomplished using hydrodynamic simulations in conjunction with Haan's saturation model, which was used to predict the mix levels of candidate experimental configurations. These theoretical predictions were then compared to the mixing information which was extracted from the experimental data, and it was found that Haan's mix model predicted trends in the width of the mix layer as a function of initial shell thickness. These results contribute to an assessment of the range of validity and predictive capability of the Haan saturation model, as well as increasing confidence in the methods used to extract mixing information from experimental data.     

A uniqueness theorem for functions in the extended Selberg class

Recently, we proved that every finite dimensional Alexandrov space is strongly locally Lipschitz contractible. In the present paper, we consider the set \(\mathcal M\) of all isometry classes of Alexandrov spaces of curvature \(\ge -1\) and of fixed dimension having upper diameter bound and lower volume bound, and prove that there exists a constant \(N\) depending on the parameters determining \(\mathcal M\) such that every space in \(\mathcal M\) can be covered by at most \(N\) strongly Lipschitz contractible balls. Also, we prove that there exists a constant \(N^\prime \) depending on \(\mathcal M\) such that every space in \(\mathcal M\) can be covered by at most \(N^\prime \) strongly Lipschitz contractible and convex regions.     

Rates of Convergence for Bivariate Extremes

Under a second order regular variation condition, rates of convergence of the distribution of bivariate extreme order statistics to its limit distribution are given both in the total variation metric and in the uniform metric.     

Domain wall effects in neutron depolarisation in Co-Cr films

The height and stripe width of the domains in Co-Cr films of 300 nm thickness is determined from angle-dependent 3-D neutron depolarisation. The effect on the data due to Bloch walls and due to domain walls identical with column boundaries is discussed. The maximum wall thickness derived is ≈ 2 and ≈ 30 nm, respectively.     

Physical properties of 3-methyl-N-butylpyridinium tetracyanoborate and 1-butyl-1-methylpyrrolidinium tetracyanoborate and ternary LLE data of [3-mebupy]B(CN)4 with an aromatic and an aliphatic hydrocarbon at T = 303.2 K and 328.2 K and p = 0.1 MPa

Several physical properties were determined for the ionic liquids 3-methyl-N-butylpyridinium tetracyanoborate ([3-mebupy]B(CN)₄) and 1-butyl-1-methylpyrrolidinium tetracyanoborate ([1-mebupyr]B(CN)₄), viz. liquid density, viscosity, surface tension, thermal stability, and heat capacity over the temperature range from 283.2 K to 475.2 K and at 0.1 MPa. The density and the surface tension were well correlated with linear equations and the viscosity with a Vogel–Fulcher–Tamman equation. The IL [3-mebupy]B(CN)₄ is stable up to a temperature of 480 K and the IL [1-mebupyr]B(CN)₄ up to a temperature of 548 K.Ternary data for the systems {(benzene + n-hexane), or (toluene + n-heptane), or (p-xylene + n-octane + [3-mebupy]B(CN)₄)} were determined at T = 303.2 K and 328.2 K and p = 0.1 MPa. All experimental data were well correlated with the NRTL model. The values of the experimental and calculated aromatic/aliphatic selectivity are in good agreement with each other. The LLE data of [1-mebupyr]B(CN)₄ were only measured in a 10 vol% aromatic feed for the three systems.     

Estimating extreme bivariate quantile regions

When simultaneously monitoring two possibly dependent, positive risks one is often interested in quantile regions with very small probability p. These extreme quantile regions contain hardly any or no data and therefore statistical inference is difficult. In particular when we want to protect ourselves against a calamity that has not yet occurred, we need to deal with probabilities p?<?1/n, with n the sample size. We consider quantile regions of the form {(x, y)?∈?(0, ∞?)²: f(x, y)?≤?β}, where f, the joint density, is decreasing in both coordinates. Such a region has the property that it consists of the less likely points and hence that its complement is as small as possible. Using extreme value theory, we construct a natural, semiparametric estimator of such a quantile region and prove a refined form of consistency. A detailed simulation study shows the very good statistical performance of the estimated quantile regions. We also apply the method to find extreme risk regions for bivariate insurance claims.