17,346 research outputs found
An Ex Post Evaluation of the Conservation Reserve, Federal Crop Insurance, and Other Government Programs: Program Participation and Soil Erosion
Recent research has questioned the extent to which government policies, including conservation and risk management programs, have influenced environmental indicators. The impacts of income-supporting and risk management programs on soil erosion are considered. An econometric model of the determinants of soil erosion, program participation, conservation effort, and input usage is estimated. While the Conservation Reserve Program has reduced erosion an average of 1.02 tons per acre from 1982 to 1992, approximately half of this reduction has been offset by increased erosion resulting from government programs other than federally subsidized crop insurance.Conservation Reserve Program, farm policy, soil erosion, Agricultural and Food Policy,
Harvest-Time Protein Shocks and Price Adjustment in U.S. Wheat Markets
Dynamic relationships between three classes of wheat are investigated using threshold VAR models incorporating the effects of protein availability. Changes in the stock of protein are found to generate significant impulse responses in the price of hard spring red wheat and hard red winter wheat but not soft red wheat. These impulse responses to identical changes in protein stocks are larger when the absolute deviations of protein stocks from normal levels are large. Shocks to the prices of individual classes of wheat result in complex impulse responses in the prices of the other wheats. Notably, however, a shock to the price of hard red winter wheat appears to result in little or no impluse response in the price of hard spring wheat, though, importantly, the opposite is not true.Demand and Price Analysis,
Domain Adaptive Neural Networks for Object Recognition
We propose a simple neural network model to deal with the domain adaptation
problem in object recognition. Our model incorporates the Maximum Mean
Discrepancy (MMD) measure as a regularization in the supervised learning to
reduce the distribution mismatch between the source and target domains in the
latent space. From experiments, we demonstrate that the MMD regularization is
an effective tool to provide good domain adaptation models on both SURF
features and raw image pixels of a particular image data set. We also show that
our proposed model, preceded by the denoising auto-encoder pretraining,
achieves better performance than recent benchmark models on the same data sets.
This work represents the first study of MMD measure in the context of neural
networks
Harvest-Time Protein Shocks and Price Adjustment in U.S. Wheat Markets
Dynamic relationships among three classes of wheat are investigated using threshold VAR models that incorporate the effects of protein availability. Changes in the stock of protein are found to generate significant responses in the prices of hard red spring wheat and hard red winter wheat, but not soft red wheat. The responses to identical changes in protein stocks are larger when the magnitudes of deviations of protein stocks from normal levels are large. Shocks to the prices of individual classes of wheat result in complex responses in the prices of the other wheat classes. Notably, however, a shock to the price of hard red winter wheat appears to result in little or no response in the price of hard spring wheat, though importantly, the opposite is not true.protein, thresholds, vector autoregressions, wheat prices, Crop Production/Industries,
A Learning-Based Approach to Caching in Heterogenous Small Cell Networks
A heterogenous network with base stations (BSs), small base stations (SBSs)
and users distributed according to independent Poisson point processes is
considered. SBS nodes are assumed to possess high storage capacity and to form
a distributed caching network. Popular files are stored in local caches of
SBSs, so that a user can download the desired files from one of the SBSs in its
vicinity. The offloading-loss is captured via a cost function that depends on
the random caching strategy proposed here. The popularity profile of cached
content is unknown and estimated using instantaneous demands from users within
a specified time interval. An estimate of the cost function is obtained from
which an optimal random caching strategy is devised. The training time to
achieve an difference between the achieved and optimal costs is
finite provided the user density is greater than a predefined threshold, and
scales as , where is the support of the popularity profile. A transfer
learning-based approach to improve this estimate is proposed. The training time
is reduced when the popularity profile is modeled using a parametric family of
distributions; the delay is independent of and scales linearly with the
dimension of the distribution parameter.Comment: 12 pages, 5 figures, published in IEEE Transactions on
Communications, 2016. arXiv admin note: text overlap with arXiv:1504.0363
A non-dispersive Raman D-band activated by well-ordered interlayer interactions in rotationally stacked bi-layer Graphene
Raman measurements on monolayer graphene folded back upon itself as an
ordered but skew-stacked bilayer (i.e. with interlayer rotation) presents new
mechanism for Raman scattering in sp2 carbons that arises in systems that lack
coherent AB interlayer stacking. Although the parent monolayer does not exhibit
a D-band, the interior of the skewed bilayer produces a strong two-peak Raman
feature near 1350 cm-1; one of these peaks is non-dispersive, unlike all
previously observed D-band features in sp2 carbons. Within a double-resonant
model of Raman scattering, these unusual features are consistent with a skewed
bilayer coupling, wherein one layer imposes a weak but well-ordered
perturbation on the other. The discrete Fourier structure of the rotated
interlayer interaction potential explains the unusual non-dispersive peak near
1350 cm-1
Non-line-of-sight Node Localization based on Semi-Definite Programming in Wireless Sensor Networks
An unknown-position sensor can be localized if there are three or more
anchors making time-of-arrival (TOA) measurements of a signal from it. However,
the location errors can be very large due to the fact that some of the
measurements are from non-line-of-sight (NLOS) paths. In this paper, we propose
a semi-definite programming (SDP) based node localization algorithm in NLOS
environment for ultra-wideband (UWB) wireless sensor networks. The positions of
sensors can be estimated using the distance estimates from location-aware
anchors as well as other sensors. However, in the absence of LOS paths, e.g.,
in indoor networks, the NLOS range estimates can be significantly biased. As a
result, the NLOS error can remarkably decrease the location accuracy.
And it is not easy to efficiently distinguish LOS from NLOS measurements. In
this paper, an algorithm is proposed that achieves high location accuracy
without the need of identifying NLOS and LOS measurement.Comment: submitted to IEEE ICC'1
Optical modeling of agricultural fields and rough-textured rock and mineral surfaces
Review was made of past models for describing the reflectance and/or emittance properties of agricultural/forestry and geological targets in an effort to select the best theoretical models. An extension of the six parameter Allen-Gayle-Richardson model was chosen as the agricultural plant canopy model. The model is used to predict the bidirectional reflectance of a field crop from known laboratory spectra of crop components and approximate plant geometry. The selected geological model is based on Mie theory and radiative transfer equations, and will assess the effect of textural variations of the spectral emittance of natural rock surfaces
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