Comparison of PBO solvers in a dependency solving domain

Linux package managers have to deal with dependencies and conflicts of packages required to be installed by the user. As an NP-complete problem, this is a hard task to solve. In this context, several approaches have been pursued. Apt-pbo is a package manager based on the apt project that encodes the dependency solving problem as a pseudo-Boolean optimization (PBO) problem. This paper compares different PBO solvers and their effectiveness on solving the dependency solving problem.Comment: In Proceedings LoCoCo 2010, arXiv:1007.083

On the Floquet Theory of Delay Differential Equations

We present an analytical approach to deal with nonlinear delay differential equations close to instabilities of time periodic reference states. To this end we start with approximately determining such reference states by extending the Poincar'e Lindstedt and the Shohat expansions which were originally developed for ordinary differential equations. Then we systematically elaborate a linear stability analysis around a time periodic reference state. This allows to approximately calculate the Floquet eigenvalues and their corresponding eigensolutions by using matrix valued continued fractions

Cost-efficient design and production of flexible and re-usable near real-time tactical human-machine interfaces

International audienceMaking complex systems accessible to human operators supposes to design HMIs that provide the operator with means to manage the complexity in an efficient manner. This is particularly true in the aeronautics domain for tactical HMIs where complexity is present in many dimensions. Current technical requirements, such as being able to display thousands of objects updated on the basis of time intervals inferior to half a second, coupled with economic requirements such as manning and cost reductions, make this issue even more crucial. We present our approach to the design and production of near real-time tactical HMIs, that enables us to devise HMIs that meet such requirements while being flexible enough to be re- used in a wide variety of contexts and produced at a reasonable cost

Wave-breaking and generic singularities of nonlinear hyperbolic equations

Wave-breaking is studied analytically first and the results are compared with accurate numerical simulations of 3D wave-breaking. We focus on the time dependence of various quantities becoming singular at the onset of breaking. The power laws derived from general arguments and the singular behavior of solutions of nonlinear hyperbolic differential equations are in excellent agreement with the numerical results. This shows the power of the analysis by methods using generic concepts of nonlinear science

Subjective Postural Vertical and Adolescent Idiopathic Scoliosis (AIS)

ObjectiveThe origin of the AIS is unknown. Several studies in AIS have shown disturbances of orthostatic postural control and somatosensory modality. The orthostatic postural control is the ability to organize the upright position on the earth-vertical, by multisensory central integration, especially somatosensory information. Our hypothesis is that the somatosensory disturbances in the AIS involve change in the organization of orthostatic postural control, around an erroneous central representation of verticality. Our objective is to test, in the AIS, the existence of a disturbance of the somatosensory modality in orthostatic postural control by measuring the Subjective Postural Vertical (SPV).MethodsUncontrolled preliminary study on 8 adolescents with SIA (7 girls, 13.8±0.83 years, 38.8±10.4°angle). Test=SPV measurement, vision obscured, head-trunk-members strapped, sitting on a seat, fixed to a German vertical wheel athletic gymnastics (external diameter: 1.90 m), with electronic inclinometer that measures the rotational tilt of the seat, with reference to the gravitational vertical. From 45° inclination, the subject is tilted (1°/sec) and evaluates the alignment with the vertical gravitational.ResultsAIS SPV=7.48±4.86° with a tilt predominance to the right. It is impossible to realize statistical evaluation in this preliminary study. Our results are comparable with those reported in pusher patient.DiscussionThis preliminary study shows a disturbance in the assessment of SPV in the AIS. Disorders of the central integration of somatosensory modality could explain this result.The authors are grateful to the Harps Association's members, for their helpful comments

Les transferis intra-européens de main d’oeuvre qualifiée: difficultés conceptuelles pour le management

Au-delà de la reconnaissance des difficultés réelles inhérentes aux voyages et à l’acclimatation à 1’étranger, les cadres qui travaillent en Europe ríont pas obtenu une reconnaissance managériale claire. Des phénomènes nouveaux, propres au «cadre européen», ont peut-être pour origine la naissance de règles particulières à 1’Union Européenne. Les directions de Ressources Humaines utilisent, en suivant un raisonnement analogique, les outils de mesure utilisés pour la gestion des RH en dimension nationale pour appréhender l’existence et les activités de cet « euromanager ». Celui-ci existe-t-il? Est-il un concept réel et opérationnel pour le management des ressources humaines à l’intemational? Comment doit-on reposer la problématique de la gestion de ces «cadres européens» dès lors qu 'emerge une spécificité européenne en la matière? Telles sont les questions auxquelles les auteurs proposent, en guise de réponse, quelques pistes de réflexion

SAT based Enforcement of Domotic Effects in Smart Environments

The emergence of economically viable and efficient sensor technology provided impetus to the development of smart devices (or appliances). Modern smart environments are equipped with a multitude of smart devices and sensors, aimed at delivering intelligent services to the users of smart environments. The presence of these diverse smart devices has raised a major problem of managing environments. A rising solution to the problem is the modeling of user goals and intentions, and then interacting with the environments using user defined goals. `Domotic Effects' is a user goal modeling framework, which provides Ambient Intelligence (AmI) designers and integrators with an abstract layer that enables the definition of generic goals in a smart environment, in a declarative way, which can be used to design and develop intelligent applications. The high-level nature of domotic effects also allows the residents to program their personal space as they see fit: they can define different achievement criteria for a particular generic goal, e.g., by defining a combination of devices having some particular states, by using domain-specific custom operators. This paper describes an approach for the automatic enforcement of domotic effects in case of the Boolean application domain, suitable for intelligent monitoring and control in domotic environments. Effect enforcement is the ability to determine device configurations that can achieve a set of generic goals (domotic effects). The paper also presents an architecture to implement the enforcement of Boolean domotic effects, and results obtained from carried out experiments prove the feasibility of the proposed approach and highlight the responsiveness of the implemented effect enforcement architectur

Geometric Friction Directs Cell Migration

In the absence of environmental cues, a migrating cell performs an isotropic random motion. Recently, the breaking of this isotropy has been observed when cells move in the presence of asymmetric adhesive patterns. However, up to now the mechanisms at work to direct cell migration in such environments remain unknown. Here, we show that a nonadhesive surface with asymmetric microgeometry consisting of dense arrays of tilted micropillars can direct cell motion. Our analysis reveals that most features of cell trajectories, including the bias, can be reproduced by a simple model of active Brownian particle in a ratchet potential, which we suggest originates from a generic elastic interaction of the cell body with the environment. The observed guiding effect, independent of adhesion, is therefore robust and could be used to direct cell migration both in vitro and in vivo

Du chaos deterministe au bruit dans des systèmes optiques avec retard

An optical device with a variational structure driven by a delayed feedback, F(x(t — d)) = sinAx(t — d) is shown to display high dimensional chaos with dimension increasing linearly with two parameters, the delay d and the feedback frequency A . For large delay d and large frequency A, the system is shown to display Gaussian-Markovian statistics like a system driven b y a white noise. Decreasing the frequency A leads to effects very similar to those of a colored noise, and decreasing the dela y leads to quite special phenomena like phase transitions, giving rise to new peaks in the probability distribution . An analytica l description using the tools of stochastic equations agrees with the numerical results .Un système optique possédant une structure variationnelle, et forcé par une rétro-injection retardée, F(x(t - d)) = sin Ax(t- d), émet un signal lumineux chaotique dont la dimension croit linéairement avec deux paramètres, le retard d et la fréquence A. Pour de grandes valeurs du retard et de la fréquence, le signal émis a une statistique Gaussienne et Markovienne, comme la solution d'une équation de Langevin forcée par un bruit blanc. Lorsqu'on diminue la valeur du paramètre A, la statistique est modifiée comme celle d'une équation de Langevin forcée par un bruit coloré. Lorsqu'on diminue le retard, de nouveaux pics apparaissent dans la distribution de probabilité, comme dans les transitions de phase induites par du bruit coloré. Une description analytique utilisant les méthodes des signaux aléatoires permet d'interpréter les résultats numériques