Journal ArticleMonthly Notices of the Royal Astronomical Society · January 17, 2023
ABSTRACTWe present a method to analyse images of the coma of 67P/Churyumov–Gerasimenko obtained using OSIRIS, the main imaging system on-board Rosetta, where dust aggregates can be seen as bright tracks because of their rel ...
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Journal ArticleAstronomy and Astrophysics · March 1, 2022
Context. During the post-perihelion phase of the European Space Agencya's Rosetta mission to comet 67P, the Optical, Spectroscopic, and Infrared Remote Imaging System on board the spacecraft took numerous image sequences of the near-nucleus coma, with many ...
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Journal ArticlePapers in Physics · January 1, 2022
In this perspective article, we discuss the challenges of imaging assemblies of particles in three dimensions. Starting from a brief motivation for the investigation of particulate ma-terials, we provide an overview of experimental approaches developed for ...
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Journal ArticleThe Review of scientific instruments · December 2021
We describe an experiment container with light scattering and imaging diagnostics for experiments on soft matter aboard the International Space Station (ISS). The suite of measurement capabilities can be used to study different materials in exchangeable sa ...
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Journal ArticleMonthly Notices of the Royal Astronomical Society · March 31, 2021
ABSTRACTWe present a method for automatized detection and analysis of quasi-periodic lineament structures from images at pixel precision. The method exploits properties of the images’ frequency domain found ...
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Journal ArticleEPJ Web of Conferences · 2021
Magnetic forces are used to heat up thousands of spherical particles under low-gravity. This long range external excitation, combined with the induced particle-particle interactions, results in a homogeneous spatial distribution of the particles. C ...
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Journal ArticlePhysical review letters · July 2020
When dense granular matter is sheared, the strain is often localized in shear bands. After some initial transient these shear bands become stationary. Here, we introduce a setup that periodically creates horizontally aligned shear bands which then migrate ...
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Journal ArticlePhysical review letters · May 2020
In contrast to molecular gases, granular gases are characterized by inelastic collisions and require therefore permanent driving to maintain a constant kinetic energy. The kinetic theory of granular gases describes how the average velocity of the particles ...
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Journal ArticlePhysical chemistry chemical physics : PCCP · July 2019
Reactive flows inside porous media play an important role in a number of geophysical and industrial processes. Here, we present three-dimensional experimental measurements on how precipitation and flow patterns change with the flow rate inside a model poro ...
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Journal ArticleSPE Journal · February 13, 2019
SummaryWe investigate the effect of the length scale of wetting heterogeneities, close to the length scale of a pore, on capillary pressure saturation (CPS) curves and the United States Bureau of Mines (USBM ...
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Journal ArticleThe Review of scientific instruments · February 2019
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The intensity of a monochromatic X-ray beam decreases exponentially with the distance it has traveled inside a material; this behavior is commonly referred to as Beer-Lambert's law. Knowledge of the material-specific attenuation coefficient μ allows us to ...
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Journal ArticleSoft matter · September 2018
Our understanding of the structural features of foams and emulsions has advanced significantly over the last 20 years. However, with a search for "super-stable" liquid dispersions, foam and emulsion science employs increasingly complex formulations which c ...
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Journal ArticleSoft matter · June 2018
The mechanisms underlying triboelectric charging have a stochastic nature. We investigate how this randomness affects the distributions of charges generated on granular particles during either a single or many collisions. The charge distributions we find i ...
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Journal ArticlePhysical review letters · February 2018
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We present an experiment on crystallization of packings of macroscopic granular spheres. This system is often considered to be a model for thermally driven atomic or colloidal systems. Cyclically shearing a packing of frictional spheres, we observe a first ...
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Journal ArticlePhysical review. E · June 2017
Equal volume mixtures of small and large polytetrafluorethylene spheres are shaken in an atmosphere of controlled humidity which allows one to also control their tribocharging. We find that the contact numbers are charge dependent: As the charge density of ...
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Journal ArticleThe Review of scientific instruments · May 2017
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Starting from three-dimensional volume data of a granular packing, as, e.g., obtained by X-ray Computed Tomography, we discuss methods to first detect the individual particles in the sample and then analyze their properties. This analysis includes the pair ...
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Journal ArticleSoft matter · January 2017
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We study the effect of humidity on the charge accumulation of polymer granulates shaken vertically in a stainless steel container. This setup allows us to control the humidity level from 5% to 100%RH while performing automated charge measurements in a Fara ...
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Journal ArticleScientific reports · October 2016
By mixing glass beads with a curable polymer we create a well-defined cohesive granular medium, held together by solidified, and hence elastic, capillary bridges. This material has a geometry similar to a wet packing of beads, but with an additional contro ...
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Journal ArticleSoft matter · May 2016
We extend the Widom particle insertion method [B. Widom, J. Chem. Phys., 1963, 39, 2808-2812] to determine an upper bound sub on the Edwards entropy in frictional hard-sphere packings. sub corresponds to the logarithm of the number of mechanically stable c ...
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Journal ArticleApplied optics · April 2016
Optically transparent immersion liquids with refractive index (n∼1.77) to match the sapphire-based aplanatic numerical aperture increasing lens (aNAIL) are necessary for achieving deep 3D imaging with high spatial resolution. We report that antimony tribro ...
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Journal ArticlePhysical review letters · April 2015
In particulate soft matter systems the average number of contacts Z of a particle is an important predictor of the mechanical properties of the system. Using x-ray tomography, we analyze packings of frictional, oblate ellipsoids of various aspect ratios α, ...
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Journal Article · January 19, 2015
The mechanical properties of a granular sample depend frequently on the way
the packing was prepared. However, is not well understood which properties of
the packing store this information. Here we present an X-ray tomography study
of three pairs of tetrah ...
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Journal ArticleSoft matter · June 2014
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Jammed packings of granular materials differ from systems normally described by statistical mechanics in that they are athermal. In recent years a statistical mechanics of static granular media has emerged where the thermodynamic temperature is replaced by ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · October 2013
We present a new mode of transport of spherical particles in a horizontally vibrated channel with sawtooth-shaped side walls. The underlying driving mechanism is based on an interplay of directional energy injection transformed by the sidewall collisions a ...
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Journal ArticlePhysical review letters · July 2013
We prepare packings of frictional tetrahedra with volume fractions ϕ ranging from 0.469 to 0.622 using three different experimental protocols under isobaric conditions. Analysis via x-ray microtomography reveals that the contact number Z grows with ϕ, but ...
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Journal Article · June 18, 2012
Granular segregation is ubiquitous in industrial, geological or daily-life
context, but there is still no unifying theoretical approach. In this review,
we examine two examples of granular segregation -- shallow rapid flows and
rotating drums -- which sugg ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · September 2011
A method of modifying the roughness of soda-lime glass spheres is presented, with the purpose of tuning interparticle friction. The effect of chemical etching on the surface topography and the bulk frictional properties of grains are systematically investi ...
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Journal ArticleThe Journal of the Acoustical Society of America · April 2011
Sound propagation in water-saturated granular sediments is known to depend on the sediment porosity, but few data in the literature address both the frequency and porosity dependency. To begin to address this deficiency, a fluidized bed technique was used ...
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Journal ArticleLangmuir : the ACS journal of surfaces and colloids · November 2010
We study the formation of capillary bridges between micrometer-sized glass spheres immersed in a binary liquid mixture using bright field and confocal microscopy. The bridges form upon heating due to the preferential wetting of the hydrophilic glass surfac ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · January 2009
We explore experimentally the fluidization of vertically agitated polymethylmethacrylate spheres wetted by liquid 4He . By controlling the temperature around the lambda point, we change the properties of the wetting liquid from a normal fluid (helium I) to ...
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Journal ArticlePhysical review letters · July 2008
Using sedimentation to obtain precisely controlled packings of noncohesive spheres, we find that the volume fraction phiRLP of the loosest mechanically stable packing is in an operational sense well defined by a limit process. This random loose packing vol ...
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Journal ArticlePhysik in unserer Zeit · November 2007
AbstractGranulare Medien, wie Sand, Salz, Kohle oder Kaffeebohnen, lassen sich durch vertikales Schütteln entmischen. In Abhängigkeit von der Schüttelamplitude sammeln sich die größeren Teilchen entweder an der Oberfläche ( ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · October 2007
Vertical shaking of a mixture of small and large beads can lead to segregation where the large beads either accumulate at the top of the sample, the so-called Brazil nut effect (BNE), or at the bottom, the reverse Brazil nut effect (RBNE). Here we demonstr ...
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Journal ArticleProceedings of the National Academy of Sciences of the United States of America · June 2007
Past work has shown that ions can pass through a membrane more readily in one direction than the other. We demonstrate here in a model and an experiment that for a mixture of small and large particles such asymmetric diffusion can arise solely from an asym ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · July 2006
A granular mixture of particles of two sizes that is shaken vertically will in most cases segregate. If the larger particles accumulate at the top of the sample, this is called the Brazil-nut effect (BNE); if they accumulate at the bottom, it is called the ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · August 2002
In thin-layer electrodeposition the dissipated electrical energy leads to a substantial heating of the ion solution. We measured the resulting temperature field by means of an infrared camera. The properties of the temperature field correspond closely with ...
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Journal ArticlePhysical review. E, Statistical, nonlinear, and soft matter physics · April 2002
Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper. We present here measurements of the dispersion relation of the growing front. The instability ...
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