3,539 research outputs found
Effect of molecular relaxation processes on travelling wave solutions of sonic boom waveforms
Asymptotic and numerical analyses are presented for the travelling wave solution of the one-dimensional acoustic wave associated with the sonic boom, subject to thermoviscous dissipation and two molecular relaxation processes. Examination of how these relaxation processes affect the propagation of a weak shock is discussed in detail
Investigation of stratiform sulphide mineralisation at Meall Mor, South Knapdale, Argyll
A co-ordinated geochemical-geophysical-geological investigation of copper
mineralisation in the Meal1 ?46r area, South Knapdale, Argyll was carried 0th
in 1976 and followed by a drilling programme of 3 shallow holes in early 1977.
The mineralisation occursin a zone of weak stratiform sulphide mineralisation
(the pyrite zone) with a strike length of 1Okm in the Upper &ins Quartz&e
of the Middle Dalradian.
The geochemical drainage survey showed the existence of a strongly anomalous
distribution of Cu and Sb in the Abhainn Srathain draining south from .
Meal1 M&- and detailed soil sampling over the pyrite zone outlined a broad
area enriched in copper. Deeper soil sampling confirmed the anomalously
high copper values and a coincident IP anomaly was found stretching from
Meal1 M& south to the old mine workings on Abhainn Srathain, and is probably
caused by a local enrichment of pyrite and chalcopyrite within the pyrite
zone.
Three boreholes were drilled; two on coincident geochemical and geophysical
anomalies, and the third beneath the old mines at Abhainn Srathain. Copper
values in the first two holes range up to 0.24% Cu over 4.27m, but up to
1.06% Cu over 2.67m in the third and this enrichment may be related to a
later remobilisation of the disseminated chalcopyrite. The results of subsequent
drilling at two other sites are given in Appendix III
A Renormalization-Group approach to the Coulomb Gap
The free energy of the Coulomb Gap problem is expanded as a set of Feynman
diagrams, using the standard diagrammatic methods of perturbation theory. The
gap in the one-particle density of states due to long-ranged interactions
corresponds to a renormalization of the two-point vertex function. By
collecting the leading order logarithmic corrections we have derived the
standard result for the density of states in the critical dimension, d=1. This
method, which is shown to be identical to the approach of Thouless, Anderson
and Palmer to spin glasses, allows us to derive the strong-disorder behaviour
of the density of states. The use of the renormalization group allows this
derivation to be extended to all disorders, and the use of an epsilon-expansion
allows the method to be extended to d=2 and d=3. We speculate that the
renormalization group equations can also be derived diagrammatically, allowing
a simple derivation of the crossover behaviour observed in the case of weak
disorder.Comment: 16 pages, LaTeX. Diagrams available on request from
[email protected]. Changes to figure 4 and second half of section
Pre-emergence tillage in field pea effective, but timing critical
Non-Peer ReviewedOn the semi-arid prairies, it is generally recommended to seed field pea early and at a depth of 4 to 7.5 cm. Crops that emerge before weed emergence are more competitive than crops emerging at the same time or after weed emergence. Delayed seeding to control late-emerging weeds and seeding at shallower depths to promote rapid emergence may be an alternative weed management strategy. The objective of this experiment was to identify combinations of seed date, seed depth, and pre-emergent weed control to optimize yield of field pea grown without the use of herbicides
The form and auditory control of downward trends in intonation
Of all the areas of intonational research, study of the tendency of the
frequency of vocal fold vibration to decline during the course of an utterance
- F0 declination - is likely initially to be the most fruitful in determining the
interaction between perceptual and productive processes. A general
introduction to the phenomenon is augmented by analysis of different
methods of determining declination lines; theoretical treatments are then
introduced. One particular local factor contributing to the downward trend,
downstep, is discussed, and its pivotal role in the intonational phonology
developed by Janet Pierrehumbert critically examined. In the light of the
theoretical discussion, two competing hypotheses are presented as to the
mediation of the declination effect, which is the effect that of two accented
syllables in an utterance, the second has to have a lower peak F0 value than
the first for them to be judged to have equal prominence. The Global
Declination Hypothesis attributes this to the use by speakers and hearers of
one or two abstract reference lines declining through the course of a tone-unit.
The Local Declination Hypothesis attributes it to the disposition of F0
excursions surrounding the two accents as well as to the respective peak
values.
The Global Declination Hypothesis is tested by presenting listeners with
pairs of dual-peak accented utterances with the two peaks identical in F0,
without any physically present local declination, and asking them to rate the
prominence of the second peak of each such utterance. No significant
differences are found in the prominence ratings, so the Local Declination
Hypothesis appears to be favoured. That hypothesis is itself tested through
the development of a model of individual accent prominence, which
incorporates terms for surrounding unaccented context. This is then used
as the basis of a model of the perceptual constraints on the production of
intonation in the scaling of target peaks. The model predicts that local slope
between accents and slope of the context after the target accent, as well as
other local variables, jointly determine the F0 value of a peak with a
particular targetted prominence relationship with its predecessor. If the
interaccentual stretch is declining, the declination effect is predicted to
occur, ceteris paribus. The model is found to be initially acceptable. In
addition, a global interpretation of downstep is made within the model.
The mechanisms the model is suggested to represent are auditory feedback
control loops of a variety of possible degrees of complexity. An experiment
is devised to test for the basic existence of a feedback loop which is used to
prevent local slope exceeding an arbitrary threshold value. Auditory
feedback In subjects was disrupted by headphone-administration of low-pass
filtered masking noise during their utterance of a sustained vowel, and a
short and a long dual peak-accented sentence. The disruption was sufficient
to alter the apparent mechanism controlling the production of the sustained
vowel, but the Lombard effect, whereby subjects automatically raise the level
of their voice in ambient noise, was found to be a vitiating factor.
General conclusions are drawn on the nature of the declination phenomenon
In intonation, and proposals made for future research
Building an Improved Drought Climatology Using Updated Drought Tools: A New Mexico Food-Energy-Water (FEW) Systems Focus
Drought is a familiar climatic phenomenon in the United States Southwest, with complex human-environment interactions that extend beyond just the physical drought events. Due to continued climate variability and change, droughts are expected to become more frequent and/or severe in the future. Decision-makers are charged with mitigating and adapting to these more extreme conditions and to do that they need to understand the specific impacts drought has on regional and local scales, and how these impacts compare to historical conditions. Tremendous progress in drought monitoring strategies has occurred over the past several decades, with more tools providing greater spatial and temporal resolutions for a variety of variables, including drought impacts. Many of these updated tools can be used to develop improved drought climatologies for decision-makers to use in their drought risk management actions. In support of a Food-Energy-Water (FEW) systems study for New Mexico, this article explores the use of updated drought monitoring tools to analyze data and develop a more holistic drought climatology applicable for New Mexico. Based upon the drought climatology, droughts appear to be occurring with greater frequency and magnitude over the last two decades. This improved drought climatology information, using New Mexico as the example, increases the understanding of the effects of drought on the FEW systems, allowing for better management of current and future drought events and associated impacts
On the Neutrality of Flowshop Scheduling Fitness Landscapes
Solving efficiently complex problems using metaheuristics, and in particular
local searches, requires incorporating knowledge about the problem to solve. In
this paper, the permutation flowshop problem is studied. It is well known that
in such problems, several solutions may have the same fitness value. As this
neutrality property is an important one, it should be taken into account during
the design of optimization methods. Then in the context of the permutation
flowshop, a deep landscape analysis focused on the neutrality property is
driven and propositions on the way to use this neutrality to guide efficiently
the search are given.Comment: Learning and Intelligent OptimizatioN Conference (LION 5), Rome :
Italy (2011
The critical Ising model via Kac-Ward matrices
The Kac-Ward formula allows to compute the Ising partition function on any
finite graph G from the determinant of 2^{2g} matrices, where g is the genus of
a surface in which G embeds. We show that in the case of isoradially embedded
graphs with critical weights, these determinants have quite remarkable
properties. First of all, they satisfy some generalized Kramers-Wannier
duality: there is an explicit equality relating the determinants associated to
a graph and to its dual graph. Also, they are proportional to the determinants
of the discrete critical Laplacians on the graph G, exactly when the genus g is
zero or one. Finally, they share several formal properties with the Ray-Singer
\bar\partial-torsions of the Riemann surface in which G embeds.Comment: 30 pages, 10 figures; added section 4.4 in version
Radiation induced oscillatory Hall effect in high mobility GaAs/AlGaAs devices
We examine the radiation induced modification of the Hall effect in high
mobility GaAs/AlGaAs devices that exhibit vanishing resistance under microwave
excitation. The modification in the Hall effect upon irradiation is
characterized by (a) a small reduction in the slope of the Hall resistance
curve with respect to the dark value, (b) a periodic reduction in the magnitude
of the Hall resistance, , that correlates with an increase in the
diagonal resistance, , and (c) a Hall resistance correction that
disappears as the diagonal resistance vanishes.Comment: 4 pages text, 4 color figure
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