8,631 research outputs found
Phase space monitoring of exciton-polariton multistability
Dynamics of exciton-polariton multistability is theoretically investigated.
Phase portraits are used as a tool to enlighten the microscopic phenomena which
influence spin multistability of a confined polariton field as well as
ultrafast reversible spin switching. The formation of a non-radiative
reservoir, due to polariton pairing into biexcitons is found to play the lead
role in the previously reported spin switching experiments. Ways to tailor this
reservoir formation are discussed in order to obtain optimal spin switching
reliability
Menger curvature and rectifiability
For a Borel set E in R^n, the total Menger curvature of E, or c(E), is the
integral over E^3 (with respect to 1-dimensional Hausdorff measure in each
factor of E) of c(x,y,z)^2, where 1/c(x,y,z) is the radius of the circle
passing through three points x, y, and z in E.
Let H^1(X) denote the 1-dimensional Hausdorff measure of a set X. A Borel set
E in R^n is purely unrectifiable if for any Lipschitz function gamma from R to
R^n, H^1(E cap gamma(R)) = 0. It is said to be rectifiable if there exists a
countable family of Lipschitz functions gamma_i from R to R^n such that H^1(E -
union gamma_i(R)) = 0. It may be seen from this definition that any 1-set E
(that is, E Borel and 0<H^1(E)<\infty) can be decomposed into two disjoint
subsets E_irr and E_rect, where E_irr is purely unrectifiable and E_rect is
rectifiable.
Theorem. If E is a 1-set in R^n and c(E)^2 is finite, then E is rectifiable.Comment: 39 pages, 3 figures, published version, abstract added in migratio
Intellectual Property Rights and Innovation in Developing Countries: Evidence from Panel Data
n.a.
Intellectual Property Rights and Innovation around the World: Evidence from Panel Data
This article contributes to the literature on innovation and development by identifying the determinants of innovation, and the role of intellectual property rights, in industrialized and developing countries. Controlling for sample selection, I find that, in general, the level of intellectual property protection and a country's technological capital stock are positively related to research and development investments, while openness to trade has a negative effect. I also find the determinants of innovation to be different for industrialized and developing countries. This is supported by endogeneity tests showing that intellectual property protection is endogenous in industrialized countries, but not in developing countries. However, in both sub-samples, research and development investments Granger-cause intellectual property protection levels, whereas surprisingly, intellectual property protection does not Granger-cause research and development investments.Innovation, intellectual property rights, developing countries, panel data, selection model
Regression modeling for digital test of ÎŁÎ modulators
The cost of Analogue and Mixed-Signal circuit
testing is an important bottleneck in the industry, due to timeconsuming
verification of specifications that require state-ofthe-
art Automatic Test Equipment. In this paper, we apply
the concept of Alternate Test to achieve digital testing of
converters. By training an ensemble of regression models that
maps simple digital defect-oriented signatures onto Signal to
Noise and Distortion Ratio (SNDR), an average error of 1:7%
is achieved. Beyond the inference of functional metrics, we show
that the approach can provide interesting diagnosis information.Ministerio de EducaciĂłn y Ciencia TEC2007-68072/MICJunta de AndalucĂa TIC 5386, CT 30
Innovation Theories: Relevance and Implications for Developing Country Innovation
Innovation is at the basis of economic development and as such, it is instrumental for developing countries. We review the literature on innovation from the perspectives of four select branches of economics to build a conceptual framework of innovation applicable to developing countries. The conceptual framework includes insights from the surveyed literature and identifies areas of further research. Finally, we conclude with policy recommendations for innovation policies in developing countries highlighting the fact that intellectual property protection is not likely to be at the basis of innovation in these countries.Innovation, Development, Absorptive Capacity
Quality criteria benchmark for hyperspectral imagery
Hyperspectral data appear to be of a growing interest
over the past few years. However, applications for hyperspectral
data are still in their infancy as handling the significant size of
the data presents a challenge for the user community. Efficient
compression techniques are required, and lossy compression,
specifically, will have a role to play, provided its impact on remote
sensing applications remains insignificant. To assess the data
quality, suitable distortion measures relevant to end-user applications
are required. Quality criteria are also of a major interest
for the conception and development of new sensors to define their
requirements and specifications. This paper proposes a method to
evaluate quality criteria in the context of hyperspectral images.
The purpose is to provide quality criteria relevant to the impact
of degradations on several classification applications. Different
quality criteria are considered. Some are traditionnally used in
image and video coding and are adapted here to hyperspectral
images. Others are specific to hyperspectral data.We also propose
the adaptation of two advanced criteria in the presence of different
simulated degradations on AVIRIS hyperspectral images. Finally,
five criteria are selected to give an accurate representation of the
nature and the level of the degradation affecting hyperspectral
data
Saturated hydraulic conductivity determined by on ground mono-offset Ground-Penetrating Radar inside a single ring infiltrometer
In this study we show how to use GPR data acquired along the infiltration of
water inside a single ring infiltrometer to inverse the saturated hydraulic
conductivity. We used Hydrus-1D to simulate the water infiltration. We
generated water content profiles at each time step of infiltration, based on a
particular value of the saturated hydraulic conductivity, knowing the other van
Genuchten parameters. Water content profiles were converted to dielectric
permittivity profiles using the Complex Refractive Index Method relation. We
then used the GprMax suite of programs to generate radargrams and to follow the
wetting front using arrival time of electromagnetic waves recorded by a
Ground-Penetrating Radar (GPR). Theoretically, the 1D time convolution between
reflectivity and GPR signal at any infiltration time step is related to the
peak of the reflected amplitude recorded in the corresponding trace in the
radargram. We used this relation ship to invert the saturated hydraulic
conductivity for constant and falling head infiltrations. We present our method
on synthetic examples and on two experiments carried out on sand soil. We
further discuss on the uncertainties on the retrieved saturated hydraulic
conductivity computed by our algorithm from the van Genuchten parameters
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