923 research outputs found
Differential thermal analysis of lunar soil simulant
Differential thermal analysis of a lunar soil simulant, 'Minnesota Lunar Simulant-1' (MLS-1) was performed. The MLS-1 was tested in as-received form (in glass form) and with another silica. The silica addition was seen to depress nucleation events which lead to a better glass former
Trace element content and magnetic properties of commercial HOPG samples studied by ion beam microscopy and SQUID magnetometry
In this study, the impurity concentration and magnetic response of nine
highly oriented pyrolytic graphite (HOPG) samples with different grades and
from different providers were determined using ion beam microscopy and SQUID
magnetometry. Apart from sideface contaminations in the as-received state, bulk
contamination of the samples in most cases consists of disk-shaped micron-sized
particles made of Ti and V with an additional Fe contamination around the grain
perimeter. The saturation magnetization typically increases with Fe
concentration, however, there is no simple correlation between Fe content and
magnetic moment. The saturation magnetization of one, respectively six, out of
nine samples clearly exceeds the maximum contribution from pure Fe or Fe3C. For
most samples the temperature dependence of the remanence decreases linearly
with T - a dependence found previously for defect-induced magnetism (DIM) in
HOPG. We conclude that apart from magnetic impurities, additional contribution
to the ferromagnetic magnetization exists in pristine HOPG in agreement with
previous studies. A comparative study between the results of ion beam
microscopy and the commonly used EDX analysis shows clearly that EDX is not a
reliable method for quantitative trace elemental analysis in graphite,
clarifying weaknesses and discrepancies in the element concentrations given in
the recent literature.Comment: submitted to Carbo
Effect of the sample geometry on the second magnetization peak in single crystalline BaKBiO thick film
Magnetization hysteresis loop measurements performed on a single
crystalline BaKBiO superconducting thick film reveal
pronounced sample geometry dependence of the "second magnetization peak" (SMP),
i.e. a maximum in the width of occurring at the field .
In particular, it is found that the SMP vanishes decreasing the film dimension.
We argue that the observed sample geometry dependence of the SMP cannot be
accounted for by models which assume a vortex pinning enhancement as the origin
of the SMP. Our results can be understood considering the thermomagnetic
instability effect and/or non-uniform current distribution at
in large enough samples.Comment: 8 pages 3 figure
Unnesting of Copatterns
Inductive data such as finite lists and trees can elegantly be defined by constructors which allow programmers to analyze and manipulate finite data via pattern matching. Dually, coinductive data such as streams can be defined by observations such as head and tail and programmers can synthesize infinite data via copattern matching. This leads to a symmetric language where finite and infinite data can be nested. In this paper, we compile nested pattern and copattern matching into a core language which only supports simple non-nested (co)pattern matching. This core language may serve as an intermediate language of a compiler. We show that this translation is conservative, i.e. the multi-step reduction relation in both languages coincides for terms of the original language. Furthermore, we show that the translation preserves strong and weak normalisation: a term of the original language is strongly/weakly normalising in one language if and only if it is so in the other. In the proof we develop more general criteria which guarantee that extensions of abstract reduction systems are conservative and preserve strong or weak normalisation. \ua9 2014 Springer International Publishing Switzerland
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