Essentially nonoscillatory postprocessing filtering methods

High order accurate centered flux approximations used in the computation of numerical solutions to nonlinear partial differential equations produce large oscillations in regions of sharp transitions. Here, we present a new class of filtering methods denoted by Essentially Nonoscillatory Least Squares (ENOLS), which constructs an upgraded filtered solution that is close to the physically correct weak solution of the original evolution equation. Our method relies on the evaluation of a least squares polynomial approximation to oscillatory data using a set of points which is determined via the ENO network. Numerical results are given in one and two space dimensions for both scalar and systems of hyperbolic conservation laws. Computational running time, efficiency, and robustness of method are illustrated in various examples such as Riemann initial data for both Burgers' and Euler's equations of gas dynamics. In all standard cases, the filtered solution appears to converge numerically to the correct solution of the original problem. Some interesting results based on nonstandard central difference schemes, which exactly preserve entropy, and have been recently shown generally not to be weakly convergent to a solution of the conservation law, are also obtained using our filters

High order filtering methods for approximating hyberbolic systems of conservation laws

In the computation of discontinuous solutions of hyperbolic systems of conservation laws, the recently developed essentially non-oscillatory (ENO) schemes appear to be very useful. However, they are computationally costly compared to simple central difference methods. A filtering method which is developed uses simple central differencing of arbitrarily high order accuracy, except when a novel local test indicates the development of spurious oscillations. At these points, the full ENO apparatus is used, maintaining the high order of accuracy, but removing spurious oscillations. Numerical results indicate the success of the method. High order of accuracy was obtained in regions of smooth flow without spurious oscillations for a wide range of problems and a significant speed up of generally a factor of almost three over the full ENO method

The design and evaluation of a sonically enhanced tool palette

This paper describes an experiment to investigate the effectiveness of adding sound to tool palettes. Palettes have usability problems because users need to see the information they present, but they are often outside the area of visual focus. We used nonspeech sounds called earcons to indicate the current tool and when tool changes occurred so that users could tell what tool they were in wherever they were looking. Results showed a significant reduction in the number of tasks performed with the wrong tool. Therefore, users knew what the current tool was and did not try to perform tasks with the wrong one. All of this was not at the expense of making the tool palettes any more annoying to use

Assessing the Credibility of Cyber Adversaries

Online communications are ever increasing, and we are constantly faced with the challenge of whether online information is credible or not. Being able to assess the credibility of others was once the work solely of intelligence agencies. In the current times of disinformation and misinformation, understanding what we are reading and to who we are paying attention to is essential for us to make considered, informed, and accurate decisions, and it has become everyone’s business. This paper employs a literature review to examine the empirical evidence across online credibility, trust, deception, and fraud detection in an effort to consolidate this information to understand adversary online credibility – how do we know with whom we are conversing is who they say they are? Based on this review, we propose a model that includes examining information as well as user and interaction characteristics to best inform an assessment of online credibility. Limitations and future opportunities are highlighted

Piezoelectric and optical setup to measure an electrical field: Application to the longitudinal near-field generated by a tapered coax

We propose a new setup to measure an electrical field in one direction. This setup is made of a piezoelectric sintered lead zinconate titanate film and an optical interferometric probe. We used this setup to investigate how the shape of the extremity of a coaxial cable influences the longitudinal electrical near-field generated by it. For this application, we designed our setup to have a spatial resolution of 100 um in the direction of the electrical field. Simulations and experiments are presented

Dosage Microbiologique des Acides Aminés des Moûts de Raisin et des Vins

Nous avons déterminé au moyen des méthodes microbiologiques classiques dix-sept acides aminés se trouvant à l'état libre dans une série de moûts et de vins. Ces méthodes s'appliquent parfaitement à ces milieux sans autre traitement préalable qu'une neutralisation et une dilution convenable. L'arginine, la praline, la thréonine, l'acide glutamique sont les quatre acides aminés les plus abondants. Ils représentent plus de 85 0/o de l'azote aminé des moûts; dans les vins cependant, ils ne constituent plus qu'une fraction de 60 %. La fermentation alcoolique fait apparaître en effet de petites quantités d'acides aminés qui n'existaient pas à l'état libre dans les moûts; la composition azotée des vins est moins abondante mais plus variée que celle des moûts. Ces dosages montrent encore que les taux des acides aminés assimilables par les levures selon la réaction d'EHRLICH sont absents dans le moût de raisin, ou seulement présents à doses extrèmement faibles. Entre autres conséquences qui découlent de ces observations et contrairement aux notions admises jusqu'à maintenant, l'alcool isobutylique et l'alcool isoamylique des vins ne tirent leur origine que pour une part très minime de la valine et des leucines des moûts.Enfin s'il existe une certaine concordance entre les chiffres d'azote aminé obtenus par dosage microbiologique et par formoltitration dans le cas des vins rouges, les écarts obtenus pour les moûts et surtout les vins blancs suggèrent que les techniques microbiologiques dosent encore certains petits polypeptides pouvant être dégradés par les bactéries

Evolution des Aminoacides au Cours de la Maturation des Raisins

Pour compléter nos connaissances sur le métabolisme azoté du raisin et mieux déterminer les formes les plus utiles à la mutrition des microorganismes, nous avons suivi l'évolution des aminoacides du raisin au cours de sa maturation à l'aide de la chromatographie sur papier et des techniques de dosage microbiologique. La teneur de la plupart des aminoacides augmente, mais la proline est l'objet d'une accumulation considérable surtout accusée dans les jours qui précèdent la maturité. Nous avons fait cette remarque, importante par ses conséquences oenologiques, qu'au cours de la maturation, l'azote du raisin passe progressivement sous des formes de moindre valeur pour l'alimentation des levures