680,476 research outputs found
Ride quality due to road surface irregularities: Comparison of different methods applied on a set of real road profiles
Road roughness evaluation can be carried out using different approaches. Among these, the assessment of ride quality level perceived by road users is one of the most-used. In this sense, different evaluation methods have been developed in order to link the level of irregularities present on road surface profiles with the induced detrimental effects in terms of discomfort. In particular, relationships between wavelength content of road profiles and consequent level of comfort perceived had been investigated by using, in general, a mean panel ratings approach. In this paper, four ride quality evaluation methods (Ride Number, Michigan Ride Quality Index (RQI), Minnesota Ride Quality Index and frequency-weighted vertical acceleration, awz, according to ISO 2631 were applied to a set of real road profiles. The obtained results were analyzed, investigating a possible relation between the different indices, comparing them also with the most-used road roughness method worldwide: the International Roughness Index (IRI). The analyses carried out in this work have highlighted how the various rating scales may lead to a different ride quality assessment of the same road pavements. Furthermore, comparing the awz with the values obtained for the other three methods, it was found that their rating scales are set for speeds within the range 80â100 km/h. For this reason, it is necessary to identify new thresholds to be applied for lower speeds, as in the case of urban roads. In this sense, the use of the ISO 2631 approach would seem to be a useful tool
Equalities between h-type indices and definitions of rational h-type indicators
Purpose: To show for which publication-citation arrays h-type indices are equal and to reconsider rational h-type indices. Results for these research questions fill some gaps in existing basic knowledge about h-type indices.
Design/methodology/approach: The results and introduction of new indicators are based on well-known definitions.
Findings: The research purpose has been reached: answers to the first questions are obtained and new indicators are defined.
Research limitations: h-type indices do not meet the Bouyssou-Marchant independence requirement.
Practical implications: On the one hand, more insight has been obtained for well-known indices such as the h-and the g-index and on the other hand, simple extensions of existing indicators have been added to the bibliometric toolbox. Relative rational h-type indices are more useful for individuals than the existing absolute ones.
Originality/value: Answers to basic questions such as "when are the values of two h-type indices equal" are provided. A new rational h-index is introduced
Faster identification of optimal contraction sequences for tensor networks
The efficient evaluation of tensor expressions involving sums over multiple
indices is of significant importance to many fields of research, including
quantum many-body physics, loop quantum gravity, and quantum chemistry. The
computational cost of evaluating an expression may depend strongly upon the
order in which the index sums are evaluated, and determination of the
operation-minimising contraction sequence for a single tensor network (single
term, in quantum chemistry) is known to be NP-hard. The current preferred
solution is an exhaustive search, using either an iterative depth-first
approach with pruning or dynamic programming and memoisation, but these
approaches are impractical for many of the larger tensor network Ansaetze
encountered in quantum many-body physics. We present a modified search
algorithm with enhanced pruning which exhibits a performance increase of
several orders of magnitude while still guaranteeing identification of an
optimal operation-minimising contraction sequence for a single tensor network.
A reference implementation for MATLAB, compatible with the ncon() and
multienv() network contractors of arXiv:1402.0939 and arXiv:1310.8023
respectively, is supplied.Comment: 25 pages, 12 figs, 2 tables, includes reference implementation of
algorithm, v2.01. Update corrects the display of contraction sequences
involving single-tensor traces (i.e. where an index in the input appears
twice on the same tensor
Extension of the Chiral Perturbation Theory Meson Lagrangian to Order
We have derived the most general chirally invariant Lagrangian
for the meson sector at order . The result provides an extension of the
standard Gasser-Leutwyler Lagrangian to one higher order,
including as well all the odd intrinsic parity terms in the Lagrangian. The
most difficult part of the derivation was developing a systematic strategy so
as to get all of the independent terms and eliminate the redundant ones in an
efficient way. The 'equation of motion' terms, which are redundant in the sense
that they can be transformed away via field transformations, are separated out
explicitly. The resulting Lagrangian has been separated into groupings of terms
contributing to increasingly more complicated processes, so that one does not
have to deal with the full result when calculating contributions to
simple processes.Comment: 59 pages in LaTex, using RevTex macro, TRIUMF preprint TRI-PP-94-6
Solving Recurrence Relations for Multi-Loop Feynman Integrals
We study the problem of solving integration-by-parts recurrence relations for
a given class of Feynman integrals which is characterized by an arbitrary
polynomial in the numerator and arbitrary integer powers of propagators, {\it
i.e.}, the problem of expressing any Feynman integral from this class as a
linear combination of master integrals. We show how the parametric
representation invented by Baikov can be used to characterize the master
integrals and to construct an algorithm for evaluating the corresponding
coefficient functions. To illustrate this procedure we use simple one-loop
examples as well as the class of diagrams appearing in the calculation of the
two-loop heavy quark potential.Comment: 24 pages, 5 ps figures, references added, minor modifications,
published versio
Tensor product representation of topological ordered phase: necessary symmetry conditions
The tensor product representation of quantum states leads to a promising
variational approach to study quantum phase and quantum phase transitions,
especially topological ordered phases which are impossible to handle with
conventional methods due to their long range entanglement. However, an
important issue arises when we use tensor product states (TPS) as variational
states to find the ground state of a Hamiltonian: can arbitrary variations in
the tensors that represent ground state of a Hamiltonian be induced by local
perturbations to the Hamiltonian? Starting from a tensor product state which is
the exact ground state of a Hamiltonian with topological order,
we show that, surprisingly, not all variations of the tensors correspond to the
variation of the ground state caused by local perturbations of the Hamiltonian.
Even in the absence of any symmetry requirement of the perturbed Hamiltonian,
one necessary condition for the variations of the tensors to be physical is
that they respect certain symmetry. We support this claim by
calculating explicitly the change in topological entanglement entropy with
different variations in the tensors. This finding will provide important
guidance to numerical variational study of topological phase and phase
transitions. It is also a crucial step in using TPS to study universal
properties of a quantum phase and its topological order.Comment: 10 pages, 6 figure
The impact of ventilation type on the heat load of dairy cows
Received: January 31st, 2021 ; Accepted: March 27th, 2021 ; Published: November 26th, 2021 ; Correspondence: [email protected] load in cattle causes deterioration of health and reduced production of milk.
Therefore, it is necessary to protect cows by appropriate passive and active means and monitor
the air quality in barns. Based on several indicators of environmental quality, is possible to make
a more comprehensive assessment of the microclimate and more precise conclusions. This study,
was monitoring the values of air temperature, relative humidity, and air velocity in two barns with
the same volume and layout with floor dimensions of 26.6 m Ă 62.1 m. In barn 1, roof ridge of
which had underwent only partial reconstruction, there were installed fourteen basket fans with a
total fan performance Q(1)fans = 218,400 m3 h
-1
. In barn 2, there were twelve panel fans with a
total fan performance Q(2)fans = 289,320 m3 h
-1
. The resulting THI, HLI and ETIC values were
compared in relation to each other and in relation to the recommended values.
Despite the operating ventilation technology and enlargement of wall openings, the above-limit
values of climatic characteristics were observed in both barns during tropical days. There were
no differences between the barns (p Ë 0.05), in barn 1: THI(1) = 83.10 ± 0.51; HLI(1) = 85.62 ±
1.42; ETIC(1) = 27.24 ± 0.31, and in barn 2: THI(2) = 83.12 ± 0.34; HLI(2) = 85.77 ± 1.50;
ETIC(2) = 27.29 ± 0.28, however, there were found significant differences in values of
temperature indices obtained in the detailed measurements at points arranged perpendicularly, as
well as parallelly, to the direction of air velocity in the animal zone (p < 0.05)
Testing the RPI data for consistency with the theory of the cost-of-living index
This paper tests the published section level price and weight data
used in the compilation of the UK Retail Prices Index for consistency
with the theory of the cost-of-living index. We use a nonparametric test
of theoretical consistency and bootstrap statistical methods to estimate
the probability of consistency
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