Noms des grands nombres | EPFL Graph Search

Les noms des grands nombres sont des systèmes de dérivation lexicale qui permettent de nommer des nombres au-delà du langage courant. Dans les langues occidentales modernes, les grands nombres sont généralement nommés d'après l'un ou l'autre des deux systèmes incompatibles suivants : les échelles longue et courte. Ces deux systèmes définissent différemment les mots « billion », « trillion », « quadrillion » L'échelle longue définit aussi les noms « billiard », « trilliard », « quadrilliard » L'usage a souvent varié, même dans un pays donné, suivant les époques. De nos jours, le français de France emploie en principe l'échelle longue quand l'anglais des États-Unis emploie l'échelle courte. De nombreux systèmes de nommage ont été proposés pour prolonger ces échelles au-delà des noms conventionnellement admis. Par ailleurs, quelques noms ont également été inventés pour des nombres très grands ; par exemple, en mathématiques, le nombre est baptisé « gogol » et le nombre 10 est nommé «

Tracing attacks and restoring integrity with LASCAR

Alexandre Aellig, Philippe Oechslin

We present a novel method to trace the propagation of intrusions or malicious code in networked systems. Our solution is aimed at large numbers of loosely managed workstations typical of a research environment as found in CERN. The system tags events which have a potential to become harmful. On a given machine all processes that results from the tagged event are marked with the same tag and the tag is carried on to others machines if a tagged process establishes a connection. Tag creation logs are stored in a central database. When an intrusion is detected at a later time, all machines and processes that may have lost their integrity due to this incident can easily be found. This leads to a quick and effective restoration of the system. Our implementation of the system is designed to incur very little overhead on the machines and integrates easily with many flavors of the Linux operating system on any type of hardware.

2003

Adaptive Highways on a Grid

Hajir Roozbehani

The primary objective of this paper is to introduce the adaptive highways algorithm, a path planning algorithm for vehicles moving on a grid. We consider a workspace that consists of a symmetric grid and a large number of vehicles that move on the grid to accomplish a certain task. Each vehicle is assigned the task of visiting a set of randomly selected locations, which are updated over time. The dynamics of the vehicles are described by a constrained linear double-integrator model. The objective is to find, in real time, a set of trajectories that maximize the average speed of the vehicles while ensuring safety. The trajectory optimization problem is solved locally, whereas a central entity is employed for distribution of information. Safety guarantees are provided through a space reservation mechanism. Several algorithms are presented and compared in terms of performance.

Springer-Verlag Berlin2011

Solvent Effects on the Encapsulation of Divalent Ions by Benzo-18-Crown-6 and Benzo-15-Crown-5

Yoshiya Inokuchi, Thomas Rizzo

We measure UV photodissociation (UVPD) spectra of cold benzo-15-crown-5 (B15C5) and benzo-18-crown-6 (B18C6) complexes with divalent ions (M2+ = Ca2+, Sr2+, Ba2+, and Mn2+), solvated with an H2O or a CH3OH molecule: M2+·B15C5·H2O, M2+·B15C5·CH3OH, M2+·B18C6·H2O, and M2+·B18C6·CH3OH. All the species show a number of sharp vibronic bands in the 36600–37600 cm–1 region, which can be attributed to electronic transitions of the B18C6 or B15C5 component. Conformer-specific IR spectra of these complexes are also obtained by IR-UV double-resonance spectroscopy in the OH stretching region. All the IR-UV spectra of the H2O complexes show IR bands at ∼3610 and ∼3690 cm–1; these bands can be assigned to the symmetric and asymmetric OH stretching vibrations of the H2O component. The CH3OH complexes also show the stretching vibration of the OH group at ∼3630 cm–1. The H2O and the CH3OH components are directly bonded to the M2+ ion through the M2+···O bond in all the complexes, but a small difference in the conformation results in a noticeable difference in the OH stretching frequency, which enables us to determine the number of conformers. For Ca2+, Sr2+, and Mn2+, the number of conformers for the B18C6 complexes is in the range of 2–5, which is clearly larger than complexes with B15C5 (1 or 2). However, for Ba2+ the number of conformers with B18C6 (1 or 2) is almost the same as that with B15C5. This is probably because the Ba2+ ion is too large to be located in the cavity center of either B15C5 and B18C6, which provides an open site at the Ba2+ ion suitable for solvation with H2O or CH3OH. The more conformations a complex can take, the more entropically favored it is at nonzero temperatures. Hence, the larger number of conformations suggests higher stability of the complexes under solvated conditions, leading to a higher degree of ion encapsulation in solution.

American Chemical Society2015

Solvent Effects on the Encapsulation of Divalent Ions by Benzo-18-Crown-6 and Benzo-15-Crown-5

Yoshiya Inokuchi, Thomas Rizzo

American Chemical Society2015