SWEET - User manual (version 2.0)

SWEET (Shallow Water Equations Evolving in Time) is a code for the solution of the 2D de Saint Venant equations, written in their conservative form. The code adopts a Finite Differences scheme to advance in time, with a fractional step procedure. The space discretization is realized through Finite Elements, with a linear representation of the water elevation and a quadratic representation of the unit- width discharge. In this document, the physical model and the numerical schemes used for solving the resulting equations are extensively described. The accuracy of the scheme is verified in different test cases. The sequential algorithm has been ported in the parallel computing framework by using the domain decomposition approach. The Schwarz algorithm has been added to the scheme for preconditioning the iterative solution of the elliptic equation modeling the dynamics of the elevation of the water level. The performance of the parallel code are evaluated on a large size computational test case. The structure of the code is explained by a description of the role of each sub- routine and by a flowchart of the program. The input and output files are described in detail, as they constitute the user interface of the code. Both input and output files have a simple structure, and any effort has been made to simplify the procedure of the input setup for the parallel code, and to manage the output results. The PVM message passing library has been used to perform the communications in the parallel version of SWEET. A short introduction to PVM is added at the end of the present report. The SWEET package is the results of a joint work between CRS4 and Enel - Polo Idraulico e Strutturale. The authors of this document kindly acknowledge the valuable contributions of Vincenzo Pennati, from Enel - Polo Idraulico e Strutturale, and of Luca Formaggia, Alfio Quarteroni and Alan Scheinine, from CRS4. This manual is an extension and revision of the SWEET User Manual Version 1.0, 1996. The author of the former document, as well as of the largest part of the SWEET code, is Davide Ambrosi, currently at Politecnico di Torino. To him, not only our sincere thank is due, but mainly the recognizance that SWEET is and will remain a work of his

Google, come cercare (e trovare) un ago in un pagliaio

Ogni giorno, milioni di persone usano i motori di ricerca per le loro attività lavorative, informative e ludiche, il più delle volte senza curarsi dell’incredibile complessità insita nel ricercare un termine fra miliardi di pagine web. Ma anche se si ponessero il problema, in quanti immaginerebbero che dietro all’efficacia di questi strumenti di ricerca risiede una raffinata matematica? In pochissimi saprebbero spiegare come funziona un motore di ricerca, e proprio in questo risiede il vero successo di Google&Co., ossia nel fatto che milioni di persone utilizzano strumenti di complessità notevolissima grazie a un’interfaccia semplice, che chiunque è in grado di usare e che cela gelosamente tale complessità

Introduction: The goals of cognition: essays in honour of Cristiano Castelfranchi

Cristiano Castelfranchi is one of the pioneers in the theory of goals and goal-directed behavior. His first seminal contributions date back to the 70s, and his work has provided invaluable insights on a variety of topics, such as the nature and functions of mental representations, the dynamics of belief and reasoning, the anatomy of emotions and motivations, power and dependence relationships, trust and delegation, communication, norms, organizations, institutions, and agent-based social simulation. Across all these areas, Castelfranchi\u27s approach has been systematically problem-oriented and markedly interdisciplinary, achieving worldwide prominence in such diverse domains as cognitive psychology, social science, Artificial Intelligence, and philosophy of mind. What gave consistency and order to his bold and broad theorizing of the human mind and society is the view that, as he puts it in this volume, goals are the true center of cognition. This collection of essays to honor Castelfranchi\u27s outstanding career reflects both his wide interests and their unifying focus. Over sixty leading scholars in their respective fields offer comments, elaborations, extensions, and cogent criticisms of Castelfranchi\u27s ideas, exploring their implications and often uncovering unexpected connections with other theories. This collection is then completed by a survey of decades of research on the theory of goals, authored by Castelfranchi himself. Thus the volume provides not only a fitting homage to Cristiano Castelfranchi, but also an invaluable reference to anyone interested in goal-directed behavior, at both the individual and the social level

Structure and Bonding in Pentacyano(L)ferrate(II) and Pentacyano(L)ruthenate(II) Complexes (L = Pyridine, Pyrazine, and N-Methylpyrazinium): A Density Functional Study

Density Functional Theory (DFT) at the generalized gradient approximation (GGA) level has been applied to the complexes [Fe(CN)5L]n- and [Ru(CN)5L]n- (L = pyridine, pyrazine, N-methylpyrazinium), as well as to [Fe(CN)5]3- and [Ru(CN)5]3-. Full geometry optimizations have been performed in all cases. The geometrical parameters are in good agreement with available information for related systems. The role of the MII-L back-bonding was investigated by means of a L and cyanide Mulliken population analysis. For both Fe(II) and Ru(II) complexes the metal-L dissociation energies follow the ordering pyridine < pyrazine < N-methyl pyrazinium, consistent with the predicted σ-donating and π*-accepting abilities of the L ligands. Also, the computed metal-L bond dissociation energies are systematically smaller in the Ru(II) than in the Fe(II) complexes. This fact suggests that previous interpretations of kinetic data, showing that ruthenium complexes in aqueous solution are more inert than their iron analogues, are not related to a stronger Ru-L bond but are probably due to solvation effects