1,721,046 research outputs found
On a quadratic functional for scalar conservation laws
Full text linkWe prove a quadratic interaction estimate for approximate solutions to scalar conservation laws obtained by the wavefront tracking approximation or the Glimm scheme. This quadratic estimate has been used in the literature to prove the convergence rate of the Glimm scheme. The proof is based on the introduction of a quadratic functional (t), decreasing at every interaction, and such that its total variation in time is bounded. Differently from other interaction potentials present in the literature, the form of this functional is the natural extension of the original Glimm functional, and coincides with it in the genuinely nonlinear case
Quadratic interaction functional for systems of conservation laws: a case study
Full text linkWe prove a quadratic interaction estimate for wavefront approximate solutions to the triangular system of conservation laws
This quadratic estimate has been used in the literature to prove the convergence rate of the Glimm scheme \cite{anc_mar_11_CMP}.
Our aim is to extend the analysis, done for scalar conservation laws \cite{bia_mod_13}, in the presence of transversal interactions among wavefronts of different families.
The proof is based on the introduction of a quadratic functional , decreasing at every interaction, and such that its total variation in time is bounded. %cancellations it variation is controlled by the total variation growths at most of the total variation of the solution multiplied by the amount of cancellation.
The study of this particular system is a key step in the proof of the quadratic interaction estimate for general systems: it requires a deep analysis of the wave structure of the solution and the reconstruction of the past history of each wavefront involved in an interaction
Quadratic interaction functional for general systems of conservation laws
Full text linkFor the Glimm scheme approximation u_\e to the solution of the system of conservation laws in one space dimension
\begin{equation*}
u_t + f(u)_x = 0, \qquad u(0,x) = u_0(x) \in \R^n,
\end{equation*}
with initial data with small total variation, we prove a quadratic (w.r.t. \TV(u_0)) interaction estimate, which has been used in the literature for stability and convergence results. No assumptions on the structure of the flux are made (apart smoothness), and this estimate is the natural extension of the Glimm type interaction estimate for genuinely nonlinear systems.
More precisely we obtain the following results:
\begin{itemize}
\item a new analysis of the interaction estimates of simple waves;
\item a Lagrangian representation of the derivative of the solution, i.e. a map which follows the trajectory of each wave from its creation to its cancellation;
\item the introduction of the characteristic interval and partition for couples of waves, representing the common history of the two waves;
\item a new functional controlling the variation in speed of the waves w.r.t. time.
\end{itemize}
This last functional is the natural extension of the Glimm functional for genuinely nonlinear systems.
The main result is that the distribution is a measure with total mass \leq \const \TV(u_0)^2
Pseudoradial order of pseudoradial spaces
No full textPseudoradial normal spaces of any order of pseudoradiality given by an ordinal number not greater than are constructed. Another construction with similar properties is given for compact spaces. Finally pseudoradial spaces of cardinality and pseudoradial order are exhibited. The most important tools to perform such constructions are those contained in Lemma 2.7, Theorem 2.8, Theorem 4.2 and Theorem 5.2
Sulla determinazione della capacita` portante di puntelli telescopici regolabili in acciaio in accordo alla norma UNI-EN 1065
No full textChoix et problèmes de traduction du livre Prédiscours. Sens, mémoire, cognition de Marie-Anne Paveau
No full textL’article présente des réflexions sur la traduction de l’ouvrage Prédiscours. Sens,
mémoire, cognition de Marie-Anne Paveau en italien. Dans un premier temps, nous
situerons la notion de prédiscours proposée par l’auteure dans la tradition de l'analyse
du discours française, afin de mettre en évidence les apports théoriques qu’elle
représente et l’importance de son intégration dans le panorama de la linguistique
italienne, en particulier de la pragmatique. Dans un deuxième temps, nous nous
concentrerons sur certains choix de traduction afin de montrer plus en détail comment
cette notion peut être mise en œuvre dans le domaine de la pragmatique telle qu’elle
s’est développée en Italie, où la question de l’articulation entre connaissances partagées
et préalables à la formulation en discours, construction du sens et matérialité
linguistique n’a pas encore été pleinement prise en compte, malgré le rôle important
reconnu à l'intersubjectivité en pragmatique et aussi en sémiotique, à travers la notiond’« Encyclopédie » d’Eco
Biogas trace compounds impact on high-temperature fuel cells short stack performance
No full textNowadays the most important issues for commercial SOFC systems are related to their durability and stability of performance both of which are affected by fuel feeding composition. The trace compounds contained in biogenous fuels can interact with SOFC components causing evident drops in performance and severely reducing the lifetime of the entire system. Due to the significant impact on SOFC performance from widely varying fuel inputs, the influence of trace compounds should be investigated in real case studies and practical applications. Anode deactivation and porous blocking electrodes are the main consequences that occur due to the presence of trace compounds impact. This work shows an experimental case study where the anode supported solid oxide fuel cells short stacks are fed with fuels containing trace compounds. These compounds were selected from the biological decomposition of organic matters. In addition, sulphur compounds were selected chlorine, aromatic compounds, terpenes, and carboxyl compounds were selected. The most deleterious impact on the stack was due to the sulphur action. However, chlorine compounds also affected the external part of the cell causing the stack to break due to the corrosion of the sealant
[Our experience with regard to congenital anomalies of the bile passages (with presentation of 13 clinical cases)]
No full textThirteen cases of congenital anomalies of the bile passages are described, as observed in the Verona Surgical Clinic during the period 1970-75, out of a total of 908 operations on the biliary passages and hence with a frequency of about 1.6%. They consisted of one case each of agenesis of the gall-bladder, septal gall-bladder, clepsydra gall-bladder, Hartmann's sac, diverticulum of the gall-bladder, outlet of the right hepatic in gall-bladder, outlet of cystic duct in third duodenal portion, accessory cholecystobiliary ducts, three cases of outlet of cystic duct in right hepatic duct, and two cases of common choledocho-wirsunghian canal. After a brief description of the individual types of anomaly, the main data in the relevant literature are considered, with a review of the semeiological and therapeutic aspects of the most frequent anomalies
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