Contracts and Behavioral Patterns for SoS: The EU IP DANSE approach

This paper presents some of the results of the first year of DANSE, one of the first EU IP projects dedicated to SoS. Concretely, we offer a tool chain that allows to specify SoS and SoS requirements at high level, and analyse them using powerful toolsets coming from the formal verification area. At the high level, we use UPDM, the system model provided by the british army as well as a new type of contract based on behavioral patterns. At low level, we rely on a powerful simulation toolset combined with recent advances from the area of statistical model checking. The approach has been applied to a case study developed at EADS Innovation Works.Comment: In Proceedings AiSoS 2013, arXiv:1311.319

Quantum theory of spontaneous and stimulated emission of surface plasmons

We introduce a quantization scheme that can be applied to surface waves propagating along a plane interface. An important result is the derivation of the energy of the surface wave for dispersive non-lossy media without invoking any specific model for the dielectric constant. Working in Coulomb's gauge, we use a modal representation of the fields. Each mode can be associated with a quantum harmonic oscillator. We have applied the formalism to derive quantum-mechanically the spontaneous emission rate of surface plasmon by a two-level system. The result is in very good agreement with Green's tensor approach in the non-lossy case. Green's approach allows also to account for losses, so that the limitations of a quantum approach of surface plasmons are clearly defined. Finally, the issue of stimulated versus spontaneous emission has been addressed. Because of the increasing density of states near the asymptote of the dispersion relation, it is quantitatively shown that the stimulated emission probability is too small to obtain gain in this frequency region.Comment: 14 pages, 5 figures, submitted to Phys. Rev. B

On the Exponentiation of Interval Matrices

The numerical computation of the exponentiation of a real matrix has been intensively studied. The main objective of a good numerical method is to deal with round-off errors and computational cost. The situation is more complicated when dealing with interval matrices exponentiation: Indeed, the main problem will now be the dependency loss of the different occurrences of the variables due to interval evaluation, which may lead to so wide enclosures that they are useless. In this paper, the problem of computing a sharp enclosure of the interval matrix exponential is proved to be NP-hard. Then the scaling and squaring method is adapted to interval matrices and shown to drastically reduce the dependency loss w.r.t. the interval evaluation of the Taylor series

Zero-shot cross-modal transfer of Reinforcement Learning policies through a Global Workspace

Humans perceive the world through multiple senses, enabling them to create a comprehensive representation of their surroundings and to generalize information across domains. For instance, when a textual description of a scene is given, humans can mentally visualize it. In fields like robotics and Reinforcement Learning (RL), agents can also access information about the environment through multiple sensors; yet redundancy and complementarity between sensors is difficult to exploit as a source of robustness (e.g. against sensor failure) or generalization (e.g. transfer across domains). Prior research demonstrated that a robust and flexible multimodal representation can be efficiently constructed based on the cognitive science notion of a 'Global Workspace': a unique representation trained to combine information across modalities, and to broadcast its signal back to each modality. Here, we explore whether such a brain-inspired multimodal representation could be advantageous for RL agents. First, we train a 'Global Workspace' to exploit information collected about the environment via two input modalities (a visual input, or an attribute vector representing the state of the agent and/or its environment). Then, we train a RL agent policy using this frozen Global Workspace. In two distinct environments and tasks, our results reveal the model's ability to perform zero-shot cross-modal transfer between input modalities, i.e. to apply to image inputs a policy previously trained on attribute vectors (and vice-versa), without additional training or fine-tuning. Variants and ablations of the full Global Workspace (including a CLIP-like multimodal representation trained via contrastive learning) did not display the same generalization abilities.Comment: Under review in a conferenc

Towards Vision-Based Smart Hospitals: A System for Tracking and Monitoring Hand Hygiene Compliance

One in twenty-five patients admitted to a hospital will suffer from a hospital acquired infection. If we can intelligently track healthcare staff, patients, and visitors, we can better understand the sources of such infections. We envision a smart hospital capable of increasing operational efficiency and improving patient care with less spending. In this paper, we propose a non-intrusive vision-based system for tracking people's activity in hospitals. We evaluate our method for the problem of measuring hand hygiene compliance. Empirically, our method outperforms existing solutions such as proximity-based techniques and covert in-person observational studies. We present intuitive, qualitative results that analyze human movement patterns and conduct spatial analytics which convey our method's interpretability. This work is a step towards a computer-vision based smart hospital and demonstrates promising results for reducing hospital acquired infections.Comment: Machine Learning for Healthcare Conference (MLHC

Aplicações de métodos da análise limite para concreto estrutural

A análise limite fornece bases teóricas sobre as quais os problemas relacionados à resistência última de estruturas de comportamento dúctil podem ser formulados e estudados. A teoria permite uma compreensão unificada do comportamento de classes distintas de elementos estruturais na ruptura, o que é valioso em particular para o dimensionamento e verificação de elementos de concreto armado. Por essa razão, ao longo do curso da história do concreto armado, diversos procedimentos de cálculo foram criados que são relacionados à teoria da análise limite em algum grau. Alguns partem da teoria com hipóteses simplificadoras para obter procedimentos de projeto simples o bastante para aplicações práticas, outros foram criados a partir da intuição e observação de experimentos, e alguns são aplicações verdadeiras das abordagens estática ou cinemática da análise limite. Estes procedimentos revelam-se valiosas ferramentas para o projeto e concepção de estruturas. Além disso, muitos aspectos da análise limite estão incorporados em normas para o dimensionamento de estruturas de concreto armado na forma de instruções ou expressões para o dimensionamento de armaduras e verificações de tensão. Estas expressões são amplamente empregadas, mas na maior parte das vezes o engenheiro ou estudante não está ciente de suas origens, limitações e da possibilidade de estendê-las e combiná-las com outros procedimentos. Os métodos associados à abordagem estática da análise limite resultam em um limite inferior para a carga última, e permitem considerações racionais dos modos internos de transferência de cargas das estruturas. São úteis para o dimensionamento e verificação de elementos com geometrias incomuns, e auxiliam na tomada de decisões sobre a definição de proporções geométricas e no dimensionamento e detalhamento da armadura de estruturas novas. Os métodos associados à abordagem cinemática permitem a análise de possíveis modos de ruptura, resultando em um limite superior para a capacidade de carga de elementos, útil para verificações mas que podem frequentemente ser empregados também para o dimensionamento. Para a aplicação destes métodos a estruturas de concreto armado, o comportamento dúctil deve ser garantido. Ductilidade em estruturas de concreto armado depende do controle dos estados de tensão e distribuições de tensões de regiões dos elementos através do arranjo das armaduras e detalhamento das zonas de ancoragem. Este trabalho tem como objetivo expor as semelhanças que estes métodos de cálculo aplicados ao concreto estrutural têm entre si por meio de suas ligações com os teoremas e conceitos da análise limite, e investigar condições que devem ser observadas para o concreto armado em particular, para aplicações práticas.Limit analysis provides the theoretical basis upon which the problems regarding the ultimate strength of structures with ductile behavior can be formulated and studied. It enables an unified understanding of the behavior of different classes of structural elements at ultimate strength, which is valuable in particular for the design and assessment of reinforced concrete elements. For this reason, along the course of the history of reinforced concrete, many calculation procedures were created which are related to theory of limit analysis to some degree. Some depart from the theory with simplifying assumptions to get design procedures simple enough for practical applications, others were crafted from intuition and observation of experiments, and a few are true applications of the static or kinematic approaches. Those procedures have shown to be valuable tools for the design and conception of structures. Besides, many aspects of limit analysis are incorporated in modern codes of practice for the design of reinforced concrete structures as instructions or expressions for dimensioning of reinforcement and stress checks. Those expressions are largely employed, but most of the time the engineer or student is not aware of its origins, limitations and the possibility of extending and combining them with other procedures. The methods associated to the static approach of limit analysis result in a lower bound for the ultimate load, and enable rational considerations of the internal modes of load transfer of structures. They are useful for design and assessment of elements with unusual geometries, and assist the decision making on geometrical proportioning and the dimensioning and detailing of rebar for new structures. The methods associated to the kinematical approach let the possible modes of failure to be considered, yielding an upper bound solution for the ultimate load of elements, useful for assessment but which can often be also used for design. For an application of these methods to reinforced concrete structures, a ductile behavior for the concrete must be ensured. Ductility in reinforced concrete structures depends on the control of the stress states and stress distributions of the regions of structural elements by means of rebar arrangement and the detailing of anchorage regions. The aim of this work is to expose the similarities that these calculation procedures for applications to structural concrete have between each other through their links to the theorems and concepts of limit analysis, and to investigate the conditions which must be met by reinforced concrete in particular for practical applications