Online Mutual Foreground Segmentation for Multispectral Stereo Videos

The segmentation of video sequences into foreground and background regions is a low-level process commonly used in video content analysis and smart surveillance applications. Using a multispectral camera setup can improve this process by providing more diverse data to help identify objects despite adverse imaging conditions. The registration of several data sources is however not trivial if the appearance of objects produced by each sensor differs substantially. This problem is further complicated when parallax effects cannot be ignored when using close-range stereo pairs. In this work, we present a new method to simultaneously tackle multispectral segmentation and stereo registration. Using an iterative procedure, we estimate the labeling result for one problem using the provisional result of the other. Our approach is based on the alternating minimization of two energy functions that are linked through the use of dynamic priors. We rely on the integration of shape and appearance cues to find proper multispectral correspondences, and to properly segment objects in low contrast regions. We also formulate our model as a frame processing pipeline using higher order terms to improve the temporal coherence of our results. Our method is evaluated under different configurations on multiple multispectral datasets, and our implementation is available online.Comment: Preprint accepted for publication in IJCV (December 2018

Reproducible Evaluation of Pan-Tilt-Zoom Tracking

Tracking with a Pan-Tilt-Zoom (PTZ) camera has been a research topic in computer vision for many years. However, it is very difficult to assess the progress that has been made on this topic because there is no standard evaluation methodology. The difficulty in evaluating PTZ tracking algorithms arises from their dynamic nature. In contrast to other forms of tracking, PTZ tracking involves both locating the target in the image and controlling the motors of the camera to aim it so that the target stays in its field of view. This type of tracking can only be performed online. In this paper, we propose a new evaluation framework based on a virtual PTZ camera. With this framework, tracking scenarios do not change for each experiment and we are able to replicate online PTZ camera control and behavior including camera positioning delays, tracker processing delays, and numerical zoom. We tested our evaluation framework with the Camshift tracker to show its viability and to establish baseline results.Comment: This is an extended version of the 2015 ICIP paper "Reproducible Evaluation of Pan-Tilt-Zoom Tracking

The structural amphiphilicity of cellulose nanocrystals characterized from their cohesion parameters

Cellulose nanocrystals (CNCs), usually considered as isotropically polar nanoparticles, are sheet-like crystalline assemblies of cellulose chains. Here, we link the anisotropy of the CNC structure to an amphiphilic behavior in suspension. The Hansen solubility parameters (HSP: δD; δP; δH) of woodbased H2SO4-hydrolyzed CNCs were measured from sedimentation tests in a wide set of 59 solvents and binary mixtures. Two sets of cohesion parameters corresponding to a polar surface (18.1; 20.4; 15.3) ± (0.5; 0.5; 0.4) MPa1/2 and to a mildly non-polar one (17.4; 4.8; 6.5) ± (0.3; 0.5; 0.6) MPa1/2 were determined, with respective solubility radii of 7.8 and 2.1MPa1/2. The polar sphere is thought to correspond to the (110)&(110) surfaces of cellulose Iβ nanocrystals, while the smaller non-polar sphere is coherent with the exposure of (200) surfaces. The HSP graph provides new insights on the amphiphilic nature of CNCs and a mapping of their chemical affnity for solvents and polymer matrices

The apparent structural hydrophobicity of cellulose nanocrystals

The Teas graph of wood-based sulfuric acid-hydrolyzed cellulose nanocrystals (CNCs) was plotted based on sedimentation tests in a set of 25 common solvents. Comparisons with those of sucrose and dextran, taken as equivalents for cellobiose (cellulose repeating unit) and amorphous cellulose, respectively, highlighted the amphiphilic nature of CNCs. In the absence of any chemical arguments, the hydrophobic behavior displayed is thought to be caused by the exposition of (200) lattice planes at the CNC surface. This apparent structural hydrophobicity may be exploited to achieve the dispersion of CNCs in some mildly-non polar matrices such as poly(ethylene glycol) and poly(lactic acid). The Teas graph is a useful tool to predict the dispersibility potential of CNCs and to select a proper solvent for nanocomposite preparatio

Sensory profile and consumer acceptability of Ziziphus mauritiana and processing product in Savannah region of Cameroon

Aim: Ziziphus mauritiana is an endemic fruit spread in the savannah region of Cameroon. The fruit, locally called Jaabi, is harvested dry and consumed as such or processed into a local cake named Yaabande, using three baking techniques (sun drying, steam baking and stifle baking). The aim of the study is to characterize the sensory profile and consumer acceptability of the fruit and its processed product, in order to evaluate the determinant of their quality attributes as influenced by ecotype, origin and processing method. Place of Study: The study was carried out in the Department of Food Science and Nutrition, University of Ngaoundéré, Cameroon. Methodology: Physico-chemical analysis, sensory profile by a semi trained panel, and consumer acceptability of the fruits and their processed products were undergone through collection of two ecotypes of the fruit (Jaabi Dakamji and Jaabi Lammuji) from four areas (Garoua, Mora, Maroua and Mokolo). African and non African consumers were used for the consumer tests. Results: Sensory analysis differentiated the fruits by ecotype and origin, with the Dakamji ecotype appearing more homogeneous whatever the origin. The processed cakes differed mainly by their texture, depending on the baking method, with chewing texture for sun processed method, while samples from steam and stifle baking were more firm in mouth. Meanwhile, all samples were acceptable at comparable level corresponding to pleasant character, the sweet taste constituting the main criteria for consuming the products, both for African and non African consumers. In this respect Dakamji ecotype was sweeter, due to its higher sugar content, while the sweetness of Lammuji ecotype was lowered by its acid content. Conclusion: Jaabi and Yaabande samples are globally acceptable by consumers, whatever the origin and the variety. Development of products emphasising the original taste of Jaabi and standardisation of processing techniques appear as some main aspects of the market development of the fruit

December 1964

Turf and Lawn Grass Association Better turf through research and Educatio

Mössbauer spectroscopy study of MgAl2O4-matrix nanocomposite powders containing carbon nanotubes and iron-based nanoparticles

Materials involved in the catalytic formation of carbon nanotubes are for the first time systematically studied by Mössbauer spectroscopy between 11 K and room temperature. Mg1−xFexAl2O4 (x=0.1, 0.2, 0.3, 0.4) solid solutions are transformed into carbon nanotubes–Fe/Fe3C–MgAl2O4 composite powders by reduction in a H2–CH4 gas mixture. The oxides are defective spinels of general formulae (Mg1−x2+Fex−3α2+Fe2α3+□αAl23+)O42−. Ferromagnetic α-Fe, ferromagnetic Fe3C and a γ-Fe form, the latter possibly corresponding to a γ-Fe–C alloy, are detected in the composite powders. An attempt is made to correlate these results with the microstructure of the powder. It seems that the nanoparticles, which catalyze the formation of the carbon nanotubes, are detected as Fe3C in the post-reaction Mössbauer spectroscopy analysis

Orienting Cellulose Nanocrystal Functionalities Tunes the Wettability of Water-Cast Films

ABSTRACT: Cellulose nanocrystal (CNC)-based materials display apparently erratic wetting behaviors with contact angle (CA) variations as large as 30° from sample to sample. This work hypothesizes that it is the orientation of CNC amphiphilic functionalities at the interface with air that causes the variability in CA. By exploiting relationships with the Hansen solubility parameter theory, a set of surface tension parameters is proposed for both the polar and the non-polar surfaces of cellulose Iβ nanocrystals. These coefficients elucidate the wettability of CNC materials by establishing a correlation between the wetting properties of the air/sample interface and its chemical composition in terms of non-polar moieties. Advancing/receding CA experiments suggest that, while spin-coating CNC suspensions yield purely polar films, oven-casting them produces amphiphilic surfaces. We proposed a mechanism where the state of dispersion (individual or agglomerated) in which CNCs reach the air/water interface during casting is the determining factor: while individual nanocrystals find it more stable to orient their non-polar surfaces toward the interface, the aspect ratio of CNC agglomerates favors an orientation of their polar surfaces. This represents the first compelling evidence of CNC orientation at an interface and can be applied to Pickering emulsions and nanocomposites and to the production of CNC materials with tuned wettability

The habitus and the critique of the present. A Wittgensteinian reading of Bourdieu’s social theory

I tackle some major criticisms addressed to Pierre Bourdieu’s notion of habitus by foregrounding its affinities with Ludwig Wittgenstein’s notion of rule-following. To this end, I first clarify the character of the habitus as a theoretical device, and then elucidate what features of Wittgenstein’s analysis Bourdieu found of interest from a methodological viewpoint. To vindicate this reading, I contend that Wittgenstein’s discussion of rule-following was meant to unearth the internal connection between rules and the performative activities whereby rules are brought into life. By portraying rules as tools that allow agents to stabilize and renegotiate practices, I illustrate the active role social agents play in the production of shared accounts of practices. I conclude by showing that, if viewed through this prism, the habitus proves to be meant to provide guidance on how social theory helps historicize and denaturalize the social world