Search results for "character"
showing 10 items of 2956 documents
HOLIMO II: a digital holographic instrument for ground-based in situ observations of microphysical properties of mixed-phase clouds
2013
Measurements of the microphysical properties of mixed-phase clouds with high spatial resolution are important to understand the processes inside these clouds. This work describes the design and characterization of the newly developed ground-based field instrument HOLIMO II (HOLographic Imager for Microscopic Objects II). HOLIMO II uses digital in-line holography to in situ image cloud particles in a well-defined sample volume. By an automated algorithm, two-dimensional images of single cloud particles between 6 and 250 μm in diameter are obtained and the size spectrum, the concentration and water content of clouds are calculated. By testing the sizing algorithm with monosized beads a system…
Band Structures in 96Zr and 98Zr Studied Through the High-Spin Beta Decays of the Y Parents
1988
The isotopes 96Zr and 98Zr are presently subject to intensive studies since their properties play a key role in the understanding of the rapid transition from spherical to deformed nuclear shapes at N ∼ 60. An interesting question is the strength of the subshell closures at Z = 38,40 and N = 56 and to which extent the structure of 96Zr, 98Zr and of their immediate neighbours is influenced by these shell effects. There is evidence, although limited, for closed- shell-or individual-particle character of these nuclei, but more information on the nature of the excited states, especially those with sizeable spins is desired. This is expected to help clarifying the situation with respect to the p…
When size matters
2017
That the unit cell of a metamaterial can't be considered vanishingly small like in ordinary crystals has long been deemed more burden than opportunity. The emergence of a characteristic length scale in metamaterial chains may change that trend.
Static chiral Willis continuum mechanics for three-dimensional chiral mechanical metamaterials
2019
International audience; Recent static experiments on twist effects in chiral three-dimensional mechanical metamaterials have been discussed in the context of micropolar Eringen continuum mechanics, which is a generalization of linear Cauchy elasticity. For cubic symmetry, Eringen elasticity comprises nine additional parameters with respect to linear Cauchy elasticity, of which three directly influence chiral effects. Here, we discuss the behavior of the static case of an alternative generalization of linear Cauchy elasticity, the Willis equations. We show that in the homogeneous static cubic case, only one additional parameter with respect to linear Cauchy elasticity results, which directly…
Digital rock physics, chemistry, and biology: challenges and prospects of pore-scale modelling approach
2021
Abstract Conventional and unconventional hydrocarbon rocks have complicated pore structures with heterogeneities distributed over various length scales (from nanometre to centimetre or even larger scales). Effective characterization of the properties of such rocks based on their digital twins is a challenging task. Digital rock physics (DRP) can be used to quantify the structural and morphological parameters of rocks directly and predict flow transport properties at the pore scale. Digital rock chemistry (DRC) or biology (DRB) applies when the changes in pore structures are due to interaction with solutes or microbial activities. Fluid–rock interactions or microbial activities complicate fl…
Persistent Currents in Small, Imperfect Hubbard Rings
2003
We have done a study with small, imperfect Hubbard rings with exact diagonalization. The results for few-electron rings show, that the imperfection, whether localized or not, nearly always decrease, but can also \emph{increase} the persistent current, depending on the character of the imperfection and the on-site interaction. The calculations are generally in agreement with more specialized studies. In most cases the electron spin plays an important role.
Hyperbolic character of the angular moment equations of radiative transfer and numerical methods
2000
We study the mathematical character of the angular moment equations of radiative transfer in spherical symmetry and conclude that the system is hyperbolic for general forms of the closure relation found in the literature. Hyperbolicity and causality preservation lead to mathematical conditions allowing to establish a useful characterization of the closure relations. We apply numerical methods specifically designed to solve hyperbolic systems of conservation laws (the so-called Godunov-type methods), to calculate numerical solutions of the radiation transport equations in a static background. The feasibility of the method in any kind of regime, from diffusion to free-streaming, is demonstrat…
Modeling electron dynamics coupled to continuum states in finite volumes with absorbing boundaries
2015
arXiv:1409.1689v1
Exact reconstruction of thz sub-λ source features in knife-edge measurements
2013
The spatial features of a sub-wavelength terahertz source are not accessible using time-integrated knife-edge techniques due to the non-separable space-time nature of the radiated field and to systematic modifications induced by the blade itself. We show that combining knife-edge with a time resolved electro-optical sampling, the space-time coupling can be addressed and the source field profile can be exactly reconstructed.
Preliminary Mechanical Characterization of Thermal Filters for the X-IFU Instrument on Athena
2018
The X-ray Integral Field Unit (X-IFU) is one of the two instruments of the Athena astrophysics space mission approved by ESA in the Cosmic Vision Science Program. The X-IFU consists of a large array of TES microcalorimeters that will operate at ~ 50 mK inside a sophisticated cryostat. A set of thin filters, highly transparent to X-rays, will be mounted on the cryostat thermal shields in order to attenuate the IR radiative load, to attenuate RF electromagnetic interferences, and to protect the detector from contamination. In this paper, we present the current thermal filters design, describe the filter samples developed/procured so far, and present preliminary results from the ongoing charac…