MIRA-3D: A three-dimensional graphical extension of pascal

MIRA-3D is a three-dimensional graphical extension of Pascal based on abstract graphical types. The user may define and manipulate complex 3D objects, as well as image transformations. Viewing transformations and attributes are compatible with the ACM GSPC Core System. A large set of graphical primitives are available and the paper discusses the most important ones. Portability has also been an important criterion in implementation.     

Charge-transfer complexes as polymerization inhibitors: 2. Studies on the mechanism of inhibition of the radical polymerizations of acrylonitrile and vinyl acetate using the amine-chloranil complexes

The mechanism of inhibition of the bulk and solution polymerizations of acrylonitrile (AN) and vinyl acetate (VA) has been investigated using the charge-transfer complexes of triethylamine (TEA) and N,N-dimethylaniline (DMA) with chloranil. Complete inhibition is achieved by the complexes of both amines for the polymerizations of both monomers. The greater inhibiting efficiency of the TEA complexes is explained in terms of their greater stabilities. The results support the idea that inhibition by quinones involves electron-transfer from the polymeric radicals to the quinone forming molecular complexes of polymeric cations and semiquinone anions. The latter are the actual inhibitors so that the efficiency of inhibition depends on the feasibility of their formation which is determined by the stability of the complexes formed. The nature of the inhibition reaction products is determined by the extent to which the semiquinone anions are found as kinetically independent species in the polymerizing system. The mechanism suggested accounts for the great differences in the inhibiting powers of quinones for the polymerizations of various monomers.     

Progressive surface reconstruction for heart mapping procedure

The composite imaging of measured cardiac properties like electrical activation and contractile properties on a reconstructed endocardial surface allows for the diagnosis of cardiac arrhythmia and myocardial infarct. However, it is difficult for an interventionalist to acquire heart surface contacts by navigating a catheter to the desired region of interest under minimal visual aid. This paper discusses a new method for the progressive reconstruction of an endocardial surface during a heart mapping procedure. A generic mesh is first aligned with a set of anchor points to obtain a first approximation of the surface. Subsequent deformations are constrained by the preservation of local surface characteristics and the fidelity of new contact points. The mesh is refined by local subdivision and its geometrical shape is further improved by edge swapping. Compared to prior art, the new method can reconstruct a realistic surface from a set of sparse and random data. It can advantageously provide a smooth reconstruction at initial acquisition and ensure a geometrical consistency between consecutive reconstructions. The accurate reconstruction of a heart chamber provides important visual cues for an interventionalist to decide on the next mapping site, thus constructively influencing the final diagnosis.     

Accurate real-time neural disparity MAP estimation with FPGA

We propose in this paper a new method for real-time dense disparity map computing using a stereo pair of rectified images. Based on the neural network and Disparity Space Image (DSI) data structure, the disparity map computing consists of two main steps: initial disparity map estimation by combining the neuronal network and the DSI structure, and its refinement. Four improvements are introduced so that an accurate and fast result will be reached. The first one concerns the proposition of a new strategy in order to optimize the computation time of the initial disparity map. In the second one, a specific treatment is proposed in order to obtain more accurate disparity for the neighboring pixels to boundaries. The third one, it concerns the pixel similarity measure for matching score computation and it consists of using in addition to the traditional pixel intensities, the magnitude and orientation of the gradients providing more accuracy. Finally, the processing time of the method has been decreased consequently to our implementation of some critical steps on FPGAs. Experimental results on real datasets are conducted and a comparative evaluation of the obtained results relative to the state-of-art methods is presented.     

Multilayered visuo-haptic hair simulation

Over the last fifteen years, research on hair simulation has made great advances in the domains of modeling, animation and rendering, and is now moving towards more innovative interaction modalities. The combination of visual and haptic interaction within a virtual hairstyling simulation framework represents an important concept evolving in this direction. Our visuo-haptic hair interaction framework consists of two layers which handle the response to the user’s interaction at a local level (around the contact area), and at a global level (on the full hairstyle). Two distinct simulation models compute individual and collective hair behavior. Our multilayered approach can be used to efficiently address the specific requirements of haptics and vision. Haptic interaction with both models has been tested with virtual hairstyling tools.

Virtual humans: thirty years of research, what next?

In this paper, we present research results and future challenges in creating realistic and believable Virtual Humans. To realize these modeling goals, real-time realistic representation is essential, but we also need interactive and perceptive Virtual Humans to populate the Virtual Worlds. Three levels of modeling should be considered to create these believable Virtual Humans: 1) realistic appearance modeling, 2) realistic, smooth and flexible motion modeling, and 3) realistic high-level behaviors modeling. At first, the issues of creating virtual humans with better skeleton and realistic deformable bodies are illustrated. To give a level of believable behavior, challenges are laid on generating on the fly flexible motion and complex behaviours of Virtual Humans inside their environments using a realistic perception of the environment. Interactivity and group behaviours are also important parameters to create believable Virtual Humans which have challenges in creating believable relationship between real and virtual humans based on emotion and personality, and simulating realistic and believable behaviors of groups and crowds. Finally, issues in generating realistic virtual clothed and haired people are presented.     

Homogeneous precipitation at solid/solution interface as a novel chemical route for synthesis of nanoparticles: application to Cd(II) and Pb(II) sulfides

Nanoparticles of CdS and PbS were prepared by a novel method in which a sparingly soluble salt of the metal is brought into contact with the preparation solution mixture, without mixing, to introduce Cd²⁺ or Pb²⁺ ion into the medium at infinitesimal doses. The aqueous solution mixture contained n-heptane; thioacetamide, as sulphide ion precursor; cetyltrimethylammonium bromide (CTAB), as capping agent; and n-butanol, as co-surfactant. At the solid/solution interface CTAB-capped nanometal sulphide is formed through a metathesis reaction in extreme dilute medium. UV-visible, FTIR, and X-ray diffraction spectroscopy, as well as transmission electron microscopy were used to characterise the nanoparticles. The results showed that in solution, the diameters of the prepared CdS and PbS are 2.67 and 1.87 nm, respectively. In crystalline form, the corresponding diameters are 3.8–6.6 nm, and 6.88–13.9 nm, respectively. The crystalline structure of CdS is cubic or hexagonal, while that of PbS is face-centred cubic. The FTIR studies proved that CTAB acted as a capping agent of the investigated nanoparticles.     

The Complexity of Problems for Quantified Constraints

In this paper we are interested in quantified propositional formulas in conjunctive normal form with “clauses” of arbitrary shapes. i.e., consisting of applying arbitrary relations to variables. We study the complexity of the evaluation problem, the model checking problem, the equivalence problem, and the counting problem for such formulas, both with and without a bound on the number of quantifier alternations. For each of these computational goals we get full complexity classifications: We determine the complexity of each of these problems depending on the set of relations allowed in the input formulas. Thus, on the one hand we exhibit syntactic restrictions of the original problems that are still computationally hard, and on the other hand we identify non-trivial subcases that admit efficient algorithms.     

What is happening now? Detection of activities of daily living from simple visual features

We propose and investigate a paradigm for activity recognition, distinguishing the “on-going activity” recognition task (OGA) from that addressing “complete activities” (CA). The former starts from a time interval and aims to discover which activities are going on inside it. The latter, in turn, focuses on terminated activities and amounts to taking an external perspective on activities. We argue that this distinction is quite natural and the OGA task has a number of interesting properties; e.g., the possibility of reconstructing complete activities in terms of on-going ones, the avoidance of the thorny issue of activity segmentation, and a straightforward accommodation of complex activities, etc. Moreover, some plausible properties of the OGA task are discussed and then investigated in a classification study, addressing: the dependence of classification performance on the duration of time windows and its relationship with actional types (homogeneous vs. non-homogeneous activities), and on the assortments of features used. Three types of visual features are exploited, obtained from a data set that tries to balance the pros and cons of laboratory-based and naturalistic ones. The results provide partial confirmation to the hypothesis and point to relevant open issues for future work.