Theory of evidence for face detection and tracking

This paper deals with face detection and tracking by computer vision for multimedia applications. Contrary to current techniques that are based on huge learning databases and complex algorithms to get generic face models (e.g., active appearance models), the proposed method handles simple contextual knowledge representative of the application background thanks to a quick supervised initialization. The transferable belief model is used to counteract the incompleteness of the prior model due first to a lack of exhaustiveness of the learning stage and secondly to the subjectivity of the task of face segmentation. The algorithm contains two main steps: detection and tracking. In the detection phase, an evidential face model is estimated by merging basic beliefs elaborated from Viola and Jones face detector and from a skin colour detector, for the assignment of mass functions. These functions are computed as the merging of sources in a specific nonlinear colour space. In order to deal with colour information dependence in the fusion process, the Den?ux cautious rule is used. The pignistic probabilities stemming from the face model guarantee the compatibility between the belief framework and the probabilistic framework. They are the entries of a bootstrap particle filter which yields face tracking at video rate. We show that the proper tuning of the evidential model parameters improves the tracking performance in real-time. Quantitative evaluation of the proposed method gives a detection rate reaching 80%, comparable to what can be found in the literature. However the proposed method requires only a weak initialization.     

Chemiluminescence detection flow cells for flow injection analysis and high-performance liquid chromatography

We have examined a range of new and previously described flow cells for chemiluminescence detection. The reactions of acidic potassium permanganate with morphine and amoxicillin were used as model systems representing the many fast chemiluminescence reactions between oxidising agents and organic analytes, and the preliminary partial reduction of the reagent was exploited to further increase the rates of reaction. The comparison was then extended to high-performance liquid chromatography separations of α- and β-adrenergic agonists, with permanganate chemiluminescence detection. Flow cells constructed by machining novel channel designs into white polymer materials (sealed with transparent films or plates) have enabled improvements in mixing efficiency and overall transmission of light to the photodetector.     

VUV synchrotron radiation: a new activation technique for tandem mass spectrometry

A novel experimental technique for tandem mass spectrometry and ion spectroscopy of electrosprayed ions using vacuum‐ultraviolet (VUV) synchrotron radiation is presented. Photon activation of trapped precursor ions has been performed by coupling a commercial linear quadrupole ion trap (Thermo scientific LTQ XL), equipped with the electrosprayed ions source, to the DESIRS beamline at the SOLEIL synchrotron radiation facility. The obtained results include, for the first time on biopolymers, photodetachment spectroscopy using monochromated synchrotron radiation of multi‐charged anions and the single photon ionization of large charge‐selected polycations. The high efficiency and signal‐to‐noise ratio achieved by the present set‐up open up possibilities of using synchrotron light as a new controllable activation method in tandem mass spectrometry of biopolymers and VUV‐photon spectroscopy of large biological ions.     

Dynamic propagation and nucleation in domain wall nanowire devices

The dynamic injection and propagation of domain walls (DWs) in technologically relevant geometries have been investigated. On short (~10 ns) timescales nucleation of a DW by a localized Oersted field is found to be well described using a Néel-Brown reversal mode. Using locally injected DWs, we test the propagation of DWs over long distances (~100 μm) in close proximity nanowires and beyond the Walker breakdown limit. In nanowires that act as true conduits to a DW, data can be successfully propagated without loss or inter-wire cross-talk. This is in contrast to poorly characterized systems where the DW is found to propagate asynchronously above the critical breakdown field.     

Formation control for second-order multi-agent systems with time-varying delays under directed topology

In this paper, we investigate a formation control problem for second-order multi-agent systems with directed graph interconnection topologies that contain time-varying coupling delays. By using a special multiple leaders’ framework, sufficient conditions are obtained for both time-invariant and time-varying formations as well as for time-varying formations for trajectory tracking, which guarantees the attainment of the formations is at exponentially converging speeds. Some numerical simulations are also conducted to validate the theoretical results.     

Range universal spaces

We characterize those topological spaces Y for which the Isbell and finest splitting topologies on the set C(X,Y) of all continuous functions from X into Y coincide for all topological spaces X. We also consider the same question for the coincidence of the restriction of the finest splitting topology on the upper semicontinuous set-valued functions to C(X,Y) and the finest splitting topology on C(X,Y). In the first case, the spaces in question are, after identifying points that are in each others closures, subsets of the two point Sierpiński space, which gives a converse and generalization of a result of S. Dolecki, G.H. Greco, and A. Lechicki. In the second case, the spaces in question are, after identifying points that are in each others closures, order bases for bounded complete continuous DCPOs with the Scott topology.     

Continuous and discontinuous Galerkin methods for a scalable three-dimensional nonhydrostatic atmospheric model: Limited-area mode

This paper describes a unified, element based Galerkin (EBG) framework for a three-dimensional, nonhydrostatic model for the atmosphere. In general, EBG methods possess high-order accuracy, geometric flexibility, excellent dispersion properties and good scalability. Our nonhydrostatic model, based on the compressible Euler equations, is appropriate for both limited-area and global atmospheric simulations. Both a continuous Galerkin (CG), or spectral element, and discontinuous Galerkin (DG) model are considered using hexahedral elements. The formulation is suitable for both global and limited-area atmospheric modeling, although we restrict our attention to 3D limited-area phenomena in this study; global atmospheric simulations will be presented in a follow-up paper. Domain decomposition and communication algorithms used by both our CG and DG models are presented. The communication volume and exchange algorithms for CG and DG are compared and contrasted. Numerical verification of the model was performed using two test cases: flow past a 3D mountain and buoyant convection of a bubble in a neutral atmosphere; these tests indicate that both CG and DG can simulate the necessary physics of dry atmospheric dynamics. Scalability of both methods is shown up to 8192 CPU cores, with near ideal scaling for DG up to 32,768 cores.     

Normal stress distribution in highly concentrated suspensions undergoing squeeze flow

Using pressure-sensitive films, the normal stress distribution is measured in suspensions of glass spheres in a Newtonian liquid undergoing constant-force squeeze flow. At volume fractions of solids up to 0.55, the normal stress distribution is independent of volume fraction and almost identical to the parabolic pressure distribution predicted for Newtonian fluids. However, at higher volume fractions, the normal stresses become an order of magnitude larger near the center and very low beyond that region. At these high volume fractions, the normal stresses decrease in the outer regions and increase in the inner regions as the squeezing proceeds. The normal stress distribution that results when the glass spheres without any fluid are subjected to squeeze flow is very similar to that for suspensions with volume fractions above 0.55, suggesting that the cause for the drastic changes in the normal stress distribution is the jamming of the particles in the suspension.     

Numerical model reduction of 2D steady incompressible laminar flows: Application on the flow over a backward-facing step

The numerical solution of most fluid mechanics problems usually needs such a fine mesh that the associated computational times become non-negligible parts in any design process. In order to couple numerical modelling schemes with inversion or control algorithms, the size of such models needs to be highly reduced. The identification method is a way to build low-order models that fit with the original ones. The laminar flow over a backward-facing step is used as a test case. Presented solutions are found to be in good agreement with experimental and numerical results found in the literature.