26,435 research outputs found
A user-oriented and computerized model for estimating vehicle ride quality
A simplified empirical model and computer program for estimating passenger ride comfort within air and surface transportation systems are described. The model is based on subjective ratings from more than 3000 persons who were exposed to controlled combinations of noise and vibration in the passenger ride quality apparatus. This model has the capability of transforming individual elements of a vehicle's noise and vibration environment into subjective discomfort units and then combining the subjective units to produce a single discomfort index typifying passenger acceptance of the environment. The computational procedures required to obtain discomfort estimates are discussed, and a user oriented ride comfort computer program is described. Examples illustrating application of the simplified model to helicopter and automobile ride environments are presented
Astrophysical factor for the reaction from -matrix analysis and asymptotic normalization coefficient for . Is any fit acceptable?
The reaction provides a path from the CN
cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor
for this reaction is dominated by resonant capture through two strong
resonances at and 962 keV and direct capture to
the ground state. Recently, a new measurement of the astrophysical factor for
the reaction has been published [P. J.
LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. The analysis has
been done using the -matrix approach with unconstrained variation of all
parameters including the asymptotic normalization coefficient (ANC). The best
fit has been obtained for the square of the ANC fm,
which exceeds the previously measured value by a factor of . Here we
present a new -matrix analysis of the Notre Dame-LUNA data with the fixed
within the experimental uncertainties square of the ANC
fm. Rather than varying the ANC we add the contribution from a
background resonance that effectively takes into account contributions from
higher levels. Altogether we present 8 fits, five unconstrained and three
constrained. In all the fits the ANC is fixed at the previously determined
experimental value fm. For the unconstrained fit with
the boundary condition , where is the energy of the
second level, we get keVb and normalized , i.e. the result which is similar to [P. J. LeBlanc {\it et
al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. From all our fits we get the range
keVb which overlaps with the result of [P. J.
LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. We address also
physical interpretation of the fitting parameters.Comment: Submitted to PR
Studies of the superconducting properties of Sn1-xInxTe (x=0.38 to 0.45) using muon-spin spectroscopy
The superconducting properties of Sn1-xInxTe (x = 0.38 to 0.45) have been
studied using magnetization and muon-spin rotation or relaxation (muSR)
measurements. These measurements show that the superconducting critical
temperature Tc of Sn1-xInxTe increases with increasing x, reaching a maximum at
around 4.8 K for x = 0.45. Zero-field muSR results indicate that time-reversal
symmetry is preserved in this material. Transverse-field muon-spin rotation has
been used to study the temperature dependence of the magnetic penetration depth
lambda(T) in the mixed state. For all the compositions studied, lambda(T) can
be well described using a single-gap s-wave BCS model. The magnetic penetration
depth at zero temperature lambda(0) ranges from 500 to 580 nm. Both the
superconducting gap Delta(0) at 0 K and the gap ratio Delta(0)/kBTc indicate
that Sn1-xInxTe (x = 0.38 to 0.45) should be considered as a superconductor
with intermediate to strong coupling.Comment: 7 pages, 6 figures, 3 table
New broad 8Be nuclear resonances
Energies, total and partial widths, and reduced width amplitudes of 8Be
resonances up to an excitation energy of 26 MeV are extracted from a coupled
channel analysis of experimental data. The presence of an extremely broad J^pi
= 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+
resonance are discovered. A previously known 22 MeV 2^+ resonance is likely
resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22
MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-?
resonances to be isospin 0.Comment: 16 pages, LaTe
Capturing Hiproofs in HOL Light
Hierarchical proof trees (hiproofs for short) add structure to ordinary proof
trees, by allowing portions of trees to be hierarchically nested. The
additional structure can be used to abstract away from details, or to label
particular portions to explain their purpose. In this paper we present two
complementary methods for capturing hiproofs in HOL Light, along with a tool to
produce web-based visualisations. The first method uses tactic recording, by
modifying tactics to record their arguments and construct a hierarchical tree;
this allows a tactic proof script to be modified. The second method uses proof
recording, which extends the HOL Light kernel to record hierachical proof trees
alongside theorems. This method is less invasive, but requires care to manage
the size of the recorded objects. We have implemented both methods, resulting
in two systems: Tactician and HipCam
Superconducting and normal-state properties of the noncentrosymmetric superconductor Re6Zr
We systematically investigate the normal and superconducting properties of
non-centrosymmetric ReZr using magnetization, heat capacity, and
electrical resistivity measurements. Resistivity measurements indicate
ReZr has poor metallic behavior and is dominated by disorder. ReZr
undergoes a superconducting transition at K. Magnetization measurements give a lower critical
field, mT. The
Werthamer-Helfand-Hohenberg model is used to approximate the upper critical
field T which is close to
the Pauli limiting field of 12.35 T and which could indicate singlet-triplet
mixing. However, low-temperature specific-heat data suggest that ReZr is
an isotropic, fully gapped s-wave superconductor with enhanced electron-phonon
coupling. Unusual flux pinning resulting in a peak effect is observed in the
magnetization data, indicating an unconventional vortex state.Comment: 11 pages, 7 figures, 2 table
Probing the superconducting ground state of the noncentrosymmetric superconductors CaTSi3 (T = Ir, Pt) using muon-spin relaxation and rotation
The superconducting properties of CaTSi3 (where T = Pt and Ir) have been
investigated using muon spectroscopy. Our muon-spin relaxation results suggest
that in both these superconductors time-reversal symmetry is preserved, while
muon-spin rotation data show that the temperature dependence of the superfluid
density is consistent with an isotropic s-wave gap. The magnetic penetration
depths and upper critical fields determined from our transverse-field muon-spin
rotation spectra are found to be 448(6) and 170(6) nm, and 3800(500) and
1700(300) G, for CaPtSi3 and CaIrSi3 respectively. The superconducting
coherence lengths of the two materials have also been determined and are 29(2)
nm for CaPtSi3 and 44(4) nm for CaIrSi3.Comment: 6 pages, 7 figure
Athlete learning in Olympic sport
High-performance sport impacts athletes beyond the physical. Coaches and coaching practice are particularly influential in shaping this learning and development. This article examines the learning identified through an inductive content analysis of eight former Olympic athletes’ career narratives. Three phases of learning could be identified across the cohort: ‘Growing into high-performance sport’, ‘Making sense of high-performance sport’, and ‘(Re)shaping high-performance sport’. A cultural perspective of learning, in particular the metaphor of ‘becoming’, is employed to interpret the Olympians’ learning experiences. The findings of this research indicate that athlete learning is bound by particular high-performance sporting contexts and career phases, yet impacted by the athletes’ individual backgrounds and dispositions. Further, data indicate that athletes’ personal development reflexively intertwines with athletic performance and performance enhancement. Implications for coaches are to: (1) involve athletes in co-constructing their sporting cultures and training contexts; and (2) provide possibilities and support for athletes to develop personally
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