2,997 research outputs found
Outdoor Thermal Environments and Activities in Open Space: An Experiment Study in Humid Subtropical Climates
The outdoor thermal environment correlates with occupant behaviors in open spaces. The appropriate range of thermal environment that is conducive to outdoor activities, however, remains inadequately defined. Existing studies fail to characterize the behavioral responses to thermal environments in important dimensions including activity types, age or gender. We conducted field studies on six open spaces in Wuhan, China, a city with humid subtropical climate and ideal for this research. Data based on field observations, questionnaires, and measurement were collected under a variety of weather conditions over 4 years. We renovated a playground by adding shading shelters and vegetation cover to reduce summertime heat stress. On-site thermal environment were assessed using the Universal Thermal Climate Index (UTCI). Findings are as following: the outdoor thermal environment is a strong predictor of mean attendance over a period of time, but not spontaneous occupancy at a specific time or space; the Optimum Thermal Environment (OTE), defined as the range in which an open space is well-attended (attendance above 90% of peak value), is more consistent than the self-reported Thermal Acceptable Range (TAR) in this study. Behavioral responses to thermal environment differ by gender, age, and types of activities. The experiment confirmed the causality between outdoor thermal environment and activities: the renovated playground attracted 80% more occupants in summer; people stayed longer, reported less heat stress, and interacted with each other more often. Results remained significant after controlling for weather, air quality, daily and weekly routines. Findings had implications for the design of open spaces.postprin
Kinetics of catalysis with surface disorder
We study the effects of generalised surface disorder on the monomer-monomer
model of heterogeneous catalysis, where disorder is implemented by allowing
different adsorption rates for each lattice site. By mapping the system in the
reaction-controlled limit onto a kinetic Ising model, we derive the rate
equations for the one and two-spin correlation functions. There is good
agreement between these equations and numerical simulations. We then study the
inclusion of desorption of monomers from the substrate, first by both species
and then by just one, and find exact time-dependent solutions for the one-spin
correlation functions.Comment: LaTex, 19 pages, 1 figure included, requires epsf.st
Generation of 3-Dimensional graph state with Josephson charge qubits
On the basis of generations of 1-dimensional and 2-dimensional graph states,
we generate a 3-dimensional N3-qubit graph state based on the Josephson charge
qubits. Since any two charge qubits can be selectively and effectively coupled
by a common inductance, the controlled phase transform between any two-qubit
can be performed. Accordingly, we can generate arbitrary multi-qubit graph
states corresponding to arbitrary shape graph, which meet the expectations of
various quantum information processing schemes. All the devices in the scheme
are well within the current technology. It is a simple, scalable and feasible
scheme for the generation of various graph states based on the Josephson charge
qubits.Comment: 4 pages, 4 figure
Frequency Reconfigurable Circular Patch Antenna with an Arc-Shaped Slot Ground Controlled by PIN Diodes
© Copyright 2017 Yao Chen et al. In this paper, a compact frequency reconfigurable circular patch antenna with an arc-shaped slot loaded in the ground layer is proposed for multiband wireless communication applications. By controlling the ON/OFF states of the five PIN diodes mounted on the arc-shaped slot, the effective length of the arc-shaped slot and the effective length of antennas current are changed, and accordingly six-frequency band reconfiguration can be achieved. The simulated and measured results show that the antenna can operate from 1.82 GHz to 2.46 GHz, which is located in DCS1800 (1.71-1.88 GHz), UMTS (2.11-2.20 GHz), WiBro (2.3-2.4 GHz), and Bluetooth (2.4-2.48 GHz) frequency bands and so forth. Compared to the common rectangular slot circular patch antenna, the proposed arc-shaped slot circular patch antenna not only has a better rotational symmetry with the circular patch and substrate but also has more compact size. For the given operating frequency at 1.82 GHz, over 55% area reduction is achieved in this design with respect to the common design with rectangular slot. Since the promising frequency reconfiguration, this antenna may have potential applications in modern multiband and multifunctional mobile communication systems
Scaling of the Equilibrium Magnetization in the Mixed State of Type-II Superconductors
We discuss the analysis of mixed-state magnetization data of type-II
superconductors using a recently developed scaling procedure. It is based on
the fact that, if the Ginzburg-Landau parameter kappa does not depend on
temperature, the magnetic susceptibility is a universal function of H/H_c2(T),
leading to a simple relation between magnetizations at different temperatures.
Although this scaling procedure does not provide absolute values of the upper
critical fieldH_c2(T), its temperature variation can be established rather
accurately. This provides an opportunity to validate theoretical models that
are usually employed for the evaluation of H_c2(T) from equilibrium
magnetization data. In the second part of the paper we apply this scaling
procedure for a discussion of the notorious first order phase transition in the
mixed state of high temperature superconductors. Our analysis, based on
experimental magnetization data available in the literature, shows that the
shift of the magnetization accross the transition may adopt either sign,
depending on the particular chosen sample. We argue that this observation is
inconsistent with the interpretation that this transition always represents the
melting transition of the vortex lattice.Comment: 18 pages, 12 figure
On War: The Dynamics of Vicious Civilizations
The dynamics of ``vicious'', continuously growing civilizations (domains),
which engage in ``war'' whenever two domains meet, is investigated. In the war
event, the smaller domain is annihilated, while the larger domain is reduced in
size by a fraction \e of the casualties of the loser. Here \e quantifies
the fairness of the war, with \e=1 corresponding to a fair war with equal
casualties on both side, and \e=0 corresponding to a completely unfair war
where the winner suffers no casualties. In the heterogeneous version of the
model, evolution begins from a specified initial distribution of domains, while
in the homogeneous system, there is a continuous and spatially uniform input of
point domains, in addition to the growth and warfare. For the heterogeneous
case, the rate equations are derived and solved, and comparisons with numerical
simulations are made. An exact solution is also derived for the case of equal
size domains in one dimension. The heterogeneous system is found to coarsen,
with the typical cluster size growing linearly in time and the number
density of domains decreases as . For the homogeneous system, two
different long-time behaviors arise as a function of \e. When 1/2<\e\leq 1
(relatively fair wars), a steady state arises which is characterized by
egalitarian competition between domains of comparable size. In the limiting
case of \e=1, rate equations which simultaneously account for the
distribution of domains and that of the intervening gaps are derived and
solved. The steady state is characterized by domains whose age is typically
much larger than their size. When 0\leq\e<1/2 (unfair wars), a few
``superpowers'' ultimately dominate. Simulations indicate that this coarsening
process is characterized by power-law temporal behavior, with non-universalComment: 43 pages, plain TeX, 12 figures included, gzipped and uuencode
Magnetoelectric properties of flexible BiFeO 3 /Ni tapes
We report ferroelectric (FE), ferromagnetic, and magnetoelectric (ME) properties of BiFeO 3 films directly deposited on flexible magnetic Ni tapes. Without use of metal-oxide and/or noble metal buffer layer between the BiFeO 3 and the Ni, both ferroelectric and magnetic properties of the film and the substrate are preserved. X-ray diffraction and transmission electron microscopy analyses confirm the formation of preferentially oriented (110) BiFeO 3 film on Ni tapes. The BiFeO 3 film has a saturation polarization and a piezoelectric d 33 coefficient of 69 ÎĽC/cm 2 and 52 pm/V, respectively. The BiFeO 3 /Ni tape shows a magnetoelectric coefficient of 3.5 mV/cm·Oe.Fil: Yan, L.. No especifĂca;Fil: Zhuo, M.. No especifĂca;Fil: Wang, Z.. Virginia Tech University; Estados UnidosFil: Yao, J.. Virginia Tech University; Estados UnidosFil: Haberkorn, Nestor Fabian. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Patagonia Norte; ArgentinaFil: Zhang, S.. No especifĂca;Fil: Civale, L.. No especifĂca;Fil: Li, J.. Virginia Tech University; Estados UnidosFil: Viehland, D.. Virginia Tech University; Estados UnidosFil: Jia, Q. X.. No especifĂca
Validation of an algorithm to evaluate the appropriateness of outpatient antibiotic prescribing using big data of Chinese diagnosis text
OBJECTIVE: We aimed to evaluate the validity of an algorithm to classify diagnoses according to the appropriateness of outpatient antibiotic use in the context of Chinese free text. SETTING AND PARTICIPANTS: A random sample of 10 000 outpatient visits was selected between January and April 2018 from a national database for monitoring rational use of drugs, which included data from 194 secondary and tertiary hospitals in China. RESEARCH DESIGN: Diagnoses for outpatient visits were classified as tier 1 if associated with at least one condition that 'always' justified antibiotic use; as tier 2 if associated with at least one condition that only 'sometimes' justified antibiotic use but no conditions that 'always' justified antibiotic use; or as tier 3 if associated with only conditions that never justified antibiotic use, using a tier-fashion method and regular expression (RE)-based algorithm. MEASURES: Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the classification algorithm, using classification made by chart review as the standard reference, were calculated. RESULTS: The sensitivities of the algorithm for classifying tier 1, tier 2 and tier 3 diagnoses were 98.2% (95% CI 96.4% to 99.3%), 98.4% (95% CI 97.6% to 99.1%) and 100.0% (95% CI 100.0% to 100.0%), respectively. The specificities were 100.0% (95% CI 100.0% to 100.0%), 100.0% (95% CI 99.9% to 100.0%) and 98.6% (95% CI 97.9% to 99.1%), respectively. The PPVs for classifying tier 1, tier 2 and tier 3 diagnoses were 100.0% (95% CI 99.1% to 100.0%), 99.7% (95% CI 99.2% to 99.9%) and 99.7% (95% CI 99.6% to 99.8%), respectively. The NPVs were 99.9% (95% CI 99.8% to 100.0%), 99.8% (95% CI 99.7% to 99.9%) and 100.0% (95% CI 99.8% to 100.0%), respectively. CONCLUSIONS: The RE-based classification algorithm in the context of Chinese free text had sufficiently high validity for further evaluating the appropriateness of outpatient antibiotic prescribing
Series expansions of the percolation probability for directed square and honeycomb lattices
We have derived long series expansions of the percolation probability for
site and bond percolation on directed square and honeycomb lattices. For the
square bond problem we have extended the series from 41 terms to 54, for the
square site problem from 16 terms to 37, and for the honeycomb bond problem
from 13 terms to 36. Analysis of the series clearly shows that the critical
exponent is the same for all the problems confirming expectations of
universality. For the critical probability and exponent we find in the square
bond case, , , in the
square site case , ,
and in the honeycomb bond case , . In addition we have obtained accurate estimates for the critical
amplitudes. In all cases we find that the leading correction to scaling term is
analytic, i.e., the confluent exponent .Comment: LaTex with epsf, 26 pages, 2 figures and 2 tables in Postscript
format included (uufiled). LaTeX version of tables also included for the
benefit of those without access to PS printers (note that the tables should
be printed in landscape mode). Accepted by J. Phys.
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