1,317 research outputs found
DEMAND FOR HEALTHY FOOD IN THE UNITED STATES
This study investigates the demand for selected healthy food groups in the United States. The original linear approximate almost ideal demand system (LA/AIDS) is modified by the use of a Laspeyres index and a normalization in order to compute demand elasticities identically to the AIDS model. The results of this study suggest that poultry is the most price elastic while cereals are the least price elastic. Fresh fruits and fresh vegetables are more price elastic than processed fruits and processed vegetables. Increasing income would induce the increases in the consumption of fresh vegetables and fruits more than that of cereals and bakery products, while increasing health risk concerns would induce the decreases in the consumption of bakery products and poultry but the increases in the consumption of fresh vegetables and cereals. The demographic variables exhibit certain effects on the demand for some healthy food groups and seasonal fluctuations statistically exist in the consumption of all food groups under study.AIDS model, elasticity, healthy food, household demand, United States, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,
Experimental investigation on performance of fabrics for indirect evaporative cooling applications
© 2016 Indirect evaporative cooling, by using water evaporation to absorb heat to lower the air temperature without adding moisture, is an extremely low energy and environmentally friendly cooling principle. The properties of the wet channel surface in an indirect evaporating cooler, i.e. its moisture wicking ability, diffusivity and evaporation ability, can greatly affect cooling efficiency and performance. Irregular fibres help to divert moisture and enlarge the wetted area, thus promoting evaporation. A range of fabrics (textiles) weaved from various fibres were experimentally tested and compared to Kraft paper, which has been conventionally used as a wet surface medium in evaporative coolers. It was found that most of the textile fabrics have superior properties in moisture wicking ability, diffusivity and evaporation ability. Compared with Kraft paper, the wicking ability of some fabrics was found to be 171%–182% higher, the diffusion ability 298%–396% higher and evaporation ability 77%–93% higher. A general assessment concerning both the moisture transfer and mechanical properties found that two of the fabrics were most suitable for indirective evaporative cooling applications
Low frequency elastic wave propagation in 2D locally resonant phononic crystal with asymmetric resonator
The resonance modes and the related effects to the transmission of elastic
waves in a two dimensional phononic crystal formed by periodic arrangements of
a two blocks unit cell in one direction are studied. The unit cell consists of
two asymmetric elliptic cylinders coated with silicon rubber and embedded in a
rigid matrix. The modes are obtained by the semi-analytic method in the least
square collocation scheme and confirmed by the finite element method
simulations. Two resonance modes, corresponding to the vibration of the
cylinder along the long and short axes, give rise to resonance reflections of
elastic waves. One mode in between the two modes, related to the opposite
vibration of the two cylinders in the unit cell in the direction along the
layer, results in the total transmission of elastic waves due to zero effective
mass density at the frequency. The resonance frequency of this new mode changes
continuously with the orientation angle of the elliptic resonator.Comment: 17 pages, 7 figure
Removal Of Active Region Inflows Reveals a Weak Solar Cycle Scale Trend In Near-surface Meridional Flow
Using time-distance local helioseismology flow maps within 1 Mm of the solar
photosphere, we detect inflows toward activity belts that contribute to solar
cycle scale variations in near-surface meridional flow. These inflows stretch
out as far as 30 degrees away from active region centroids. If active region
neighborhoods are excluded, the solar cycle scale variation in background
meridional flow diminishes to below 2~m~s, but still shows systematic
variations in the absence of active regions between Sunspot Cycles 24 and 25.
We, therefore, propose that the near-surface meridional flow is a three
component flow made up of: a constant baseline flow profile that can be derived
from quiet Sun regions, variations due to inflows around active regions, and
solar cycle scale variation of the order of 2~m~s. Torsional
oscillation, on the other hand, is found to be a global phenomenon i.e.
exclusion of active region neighborhoods does not affect its magnitude or phase
significantly. This non-variation of torsional oscillation with distance away
from active regions and the three-component breakdown of the near-surface
meridional flow serve as vital constraints for solar dynamo models and surface
flux transport simulations.Comment: 14 pages, 9 figures, accepted for publication in the Astrophysical
Journa
A Possible Mechanism for "Late Phase" in Stellar White-Light Flares
M-dwarf flares observed by the \textit{Transiting Exoplanet Survey Satellite}
(\textit{TESS}) sometimes exhibit a "peak-bump" light-curve morphology,
characterized by a secondary, gradual peak well after the main, impulsive peak.
A similar "late phase" is frequently detected in solar flares observed in the
extreme-ultraviolet from longer hot coronal loops distinct from the impulsive
flare structures. White-light emission has also been observed in off-limb solar
flare loops. Here, we perform a suite of one-dimensional hydrodynamic loop
simulations for M-dwarf flares inspired by these solar examples. Our results
suggest that coronal plasma condensation following impulsive flare heating can
yield high electron number density in the loop, allowing it to contribute
significantly to the optical light curves via free-bound and free-free emission
mechanisms. Our simulation results qualitatively agree with \textit{TESS}
observations: the longer evolutionary time scale of coronal loops produces a
distinct, secondary emission peak; its intensity increases with the injected
flare energy. We argue that coronal plasma condensation is a possible mechanism
for the \textit{TESS} late-phase flares.Comment: 31 pages, 13 figures, accepted for publication in Ap
Gallium/aluminum interdiffusion between n-GaN and sapphire
The distribution profiles of Ga and Al near the interface of the n-GaN/sapphire system were measured by x-ray energy dispersive spectroscopy (XEDS). The results are obtained by the corrected XED spectra. First, the gallium diffusing into the sapphire substrate obeys the law of remainder probability function. The gallium diffusion coefficient DGa=2.30×10-13 cm2s-1 was calculated by theoretical fitting. Second, the diffusion is associated with the GaN growth process at high temperature. Compared to the diffusion of Ga into the sapphire substrate, much less Al antidiffusion from the substrate to the GaN film, with diffusion coefficient DA1 approximately equal to 4.8×10-15 cm2s-1, was observed in the film. © 1998 American Institute of Physics.published_or_final_versio
Demonstrating the model nature of the high-temperature superconductor HgBaCuO
The compound HgBaCuO (Hg1201) exhibits a simple tetragonal
crystal structure and the highest superconducting transition temperature
(T) among all single Cu-O layer cuprates, with T = 97 K (onset) at
optimal doping. Due to a lack of sizable single crystals, experimental work on
this very attractive system has been significantly limited. Thanks to a recent
breakthrough in crystal growth, such crystals have now become available. Here,
we demonstrate that it is possible to identify suitable heat treatment
conditions to systematically and uniformly tune the hole concentration of
Hg1201 crystals over a wide range, from very underdoped (T = 47 K, hole
concentration p ~ 0.08) to overdoped (T = 64 K, p ~ 0.22). We then present
quantitative magnetic susceptibility and DC charge transport results that
reveal the very high-quality nature of the studied crystals. Using XPS on
cleaved samples, we furthermore demonstrate that it is possible to obtain large
surfaces of good quality. These characterization measurements demonstrate that
Hg1201 should be viewed as a model high-temperature superconductor, and they
provide the foundation for extensive future experimental work.Comment: 15 pages, 6 Figure
MOSE: A New Dataset for Video Object Segmentation in Complex Scenes
Video object segmentation (VOS) aims at segmenting a particular object
throughout the entire video clip sequence. The state-of-the-art VOS methods
have achieved excellent performance (e.g., 90+% J&F) on existing datasets.
However, since the target objects in these existing datasets are usually
relatively salient, dominant, and isolated, VOS under complex scenes has rarely
been studied. To revisit VOS and make it more applicable in the real world, we
collect a new VOS dataset called coMplex video Object SEgmentation (MOSE) to
study the tracking and segmenting objects in complex environments. MOSE
contains 2,149 video clips and 5,200 objects from 36 categories, with 431,725
high-quality object segmentation masks. The most notable feature of MOSE
dataset is complex scenes with crowded and occluded objects. The target objects
in the videos are commonly occluded by others and disappear in some frames. To
analyze the proposed MOSE dataset, we benchmark 18 existing VOS methods under 4
different settings on the proposed MOSE dataset and conduct comprehensive
comparisons. The experiments show that current VOS algorithms cannot well
perceive objects in complex scenes. For example, under the semi-supervised VOS
setting, the highest J&F by existing state-of-the-art VOS methods is only 59.4%
on MOSE, much lower than their ~90% J&F performance on DAVIS. The results
reveal that although excellent performance has been achieved on existing
benchmarks, there are unresolved challenges under complex scenes and more
efforts are desired to explore these challenges in the future. The proposed
MOSE dataset has been released at https://henghuiding.github.io/MOSE.Comment: MOSE Dataset Repor
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