212 research outputs found
An investigation on server-side object-scene recognition performance using coarse location information and camera phone-captured images
This paper presents a solution based on information already residing within a mobile network and aimed at the cultural tourist. It also demonstrates how scene (or landmark) recognition from an image can be achieved by combining local invariant image features, cell location information and classification based on Self-Organizing Map clustering. The proposed server-side approach makes the solution independent of the mobile platform and thus accessible to any camera- embedded mobile station having the Multimedia Messaging Service enabled.peer-reviewe
Theoretical optimal trajectories for reducing the environmental impact of commercial aircraft operations
This work describes initial results obtained from an ongoing research involving the development of optimization algorithms which are capable of performing multi-disciplinary
aircraft trajectory optimization processes. A short description of both the rationale behind the initial selection of a suitable optimization technique and the status of the optimization
algorithms is firstly presented. The optimization algorithms developed are subsequently utilized to analyze different case studies involving one or more flight phases present in
actual aircraft flight profiles. Several optimization processes focusing on the minimization of total flight time, fuel burned and oxides of nitrogen (NOx) emissions are carried out and
their results are presented and discussed. When compared with others obtained using commercially available optimizers, results of these optimization processes show atisfactory level of accuracy (average discrepancies ~2%). It is expected that these optimization algorithms can be utilized in future to efficiently compute realistic, optimal and ‘greener’ aircraft trajectories, thereby minimizing the environmental impact of
commercial aircraft operations
Characterization of uncertainties in atmospheric trace gas inversions using hierarchical Bayesian methods
We present a hierarchical Bayesian method for atmospheric trace gas
inversions. This method is used to estimate emissions of trace gases as well
as "hyper-parameters" that characterize the probability density functions
(PDFs) of the a priori emissions and model-measurement covariances. By
exploring the space of "uncertainties in uncertainties", we show that the
hierarchical method results in a more complete estimation of emissions and
their uncertainties than traditional Bayesian inversions, which rely heavily
on expert judgment. We present an analysis that shows the effect of
including hyper-parameters, which are themselves informed by the data, and
show that this method can serve to reduce the effect of errors in assumptions
made about the a priori emissions and model-measurement uncertainties. We
then apply this method to the estimation of sulfur hexafluoride (SF6)
emissions over 2012 for the regions surrounding four Advanced Global
Atmospheric Gases Experiment (AGAGE) stations. We find that improper
accounting of model representation uncertainties, in particular, can lead to
the derivation of emissions and associated uncertainties that are unrealistic
and show that those derived using the hierarchical method are likely to be
more representative of the true uncertainties in the system. We demonstrate
through this SF6 case study that this method is less sensitive to
outliers in the data and to subjective assumptions about a priori emissions
and model-measurement uncertainties than traditional methods
Fidelity of G protein -subunit association by the G protein -subunit-like domains of RGS6, RGS7, and RGS11
Several regulators of G protein signaling (RGS) proteins contain a G protein γ-subunit-like (GGL) domain, which, as we have shown, binds to Gβ5 subunits. Here, we extend our original findings by describing another GGL-domain-containing RGS, human RGS6. When RGS6 is coexpressed with different Gβ subunits, only RGS6 and Gβ5 interact. The expression of mRNA for RGS6 and Gβ5 in human tissues overlaps. Predictions of α-helical and coiled-coil character within GGL domains, coupled with measurements of Gβ binding by GGL domain mutants, support the contention that Gγ-like regions within RGS proteins interact with Gβ5 subunits in a fashion comparable to conventional Gβ/Gγ pairings. Mutation of the highly conserved Phe-61 residue of Gγ2 to tryptophan, the residue present in all GGL domains, increases the stability of the Gβ5/Gγ2 heterodimer, highlighting the importance of this residue to GGL/Gβ5 association
Fast-ion conduction and flexibility of glassy networks
We observe two thresholds in the variations of electrical conductivity of dry
solid electrolyte (AgI)x(AgPO3)1-x glasses, when the AgI additive concentration
x increases to 9.5% and to 37.8%. Raman scattering complemented by calorimetric
measurements confirm that these thresholds are signatures of the rigidity phase
transitions; at x = 9.5% from a stressed rigid to an isostatically (stress
free) rigid phase, and at x = 37.8% from isostatically rigid to a flexible
phase. In the flexible phase, the electrical conductivity seems to increase as
a power of x, this is in good agreement with the theoretical prediction based
on 3d percolation.Comment: Accepted by PR
Dielectric spectra analysis: reliable parameter estimation using interval analysis
Dielectric spectroscopy is an extremely versatile method for characterizing the molecular dynamics over a large range of time scales. Unfortunately, the extraction of model parameters by data fitting is still a crucial problem which is now solved by our program S.A.D.E. S.A.D.E. is based on the algorithm S.I.V.I.A. which was proposed and implemented by Jaulin in order to solve constraint satisfaction problems. The problem of dielectric data analysis is reduced to a problem of choosing the appropriate physical model. In this article, Debye relaxations were used and validated to fit the relaxations of a DGEBA prepolymer and the polarization of the spectrometer electrodes. The conductivity was evaluated too
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