476,161 research outputs found
COACHES Cooperative Autonomous Robots in Complex and Human Populated Environments
Public spaces in large cities are increasingly becoming complex and unwelcoming environments. Public spaces progressively become more hostile and unpleasant to use because of the overcrowding and complex information in signboards. It is in the interest of cities to make their public spaces easier to use, friendlier to visitors and safer to increasing elderly population and to citizens with disabilities. Meanwhile, we observe, in the last decade a tremendous progress in the development of robots in dynamic, complex and uncertain environments. The new challenge for the near future is to deploy a network of robots in public spaces to accomplish services that can help humans. Inspired by the aforementioned challenges, COACHES project addresses fundamental issues related to the design of a robust system of self-directed autonomous robots with high-level skills of environment modelling and scene understanding, distributed autonomous decision-making, short-term interacting with humans and robust and safe navigation in overcrowding spaces. To this end, COACHES will provide an integrated solution to new challenges on: (1) a knowledge-based representation of the environment, (2) human activities and needs estimation using Markov and Bayesian techniques, (3) distributed decision-making under uncertainty to collectively plan activities of assistance, guidance and delivery tasks using Decentralized Partially Observable Markov Decision Processes with efficient algorithms to improve their scalability and (4) a multi-modal and short-term human-robot interaction to exchange information and requests. COACHES project will provide a modular architecture to be integrated in real robots. We deploy COACHES at Caen city in a mall called “Rive de l’orne”. COACHES is a cooperative system consisting of ?xed cameras and the mobile robots. The ?xed cameras can do object detection, tracking and abnormal events detection (objects or behaviour). The robots combine these information with the ones perceived via their own sensor, to provide information through its multi-modal interface, guide people to their destinations, show tramway stations and transport goods for elderly people, etc.... The COACHES robots will use different modalities (speech and displayed information) to interact with the mall visitors, shopkeepers and mall managers. The project has enlisted an important an end-user (Caen la mer) providing the scenarios where the COACHES robots and systems will be deployed, and gather together universities with complementary competences from cognitive systems (SU), robust image/video processing (VUB, UNICAEN), and semantic scene analysis and understanding (VUB), Collective decision-making using decentralized partially observable Markov Decision Processes and multi-agent planning (UNICAEN, Sapienza), multi-modal and short-term human-robot interaction (Sapienza, UNICAEN
Structure and decays of nuclear three-body systems: the Gamow coupled-channel method in Jacobi coordinates
Weakly bound and unbound nuclear states appearing around
particle thresholds are prototypical open quantum systems. Theories of such
states must take into account configuration mixing effects in the presence of
strong coupling to the particle continuum space.
To describe structure and decays of three-body systems, we
developed a Gamow coupled-channel (GCC) approach in Jacobi coordinates by
employing the complex-momentum formalism. We benchmarked the new framework
against the complex-energy Gamow Shell Model (GSM).
The GCC formalism is expressed in Jacobi coordinates, so
that the center-of-mass motion is automatically eliminated. To solve the
coupled-channel equations, we use hyperspherical harmonics to describe the
angular wave functions while the radial wave functions are expanded in the
Berggren ensemble, which includes bound, scattering and Gamow states.
We show that the GCC method is both accurate and robust. Its
results for energies, decay widths, and nucleon-nucleon angular correlations
are in good agreement with the GSM results.
We have demonstrated that a three-body GSM formalism
explicitly constructed in cluster-orbital shell model coordinates provides
similar results to a GCC framework expressed in Jacobi coordinates, provided
that a large configuration space is employed. Our calculations for
systems and O show that nucleon-nucleon angular correlations are
sensitive to the valence-neutron interaction. The new GCC technique has many
attractive features when applied to bound and unbound states of three-body
systems: it is precise, efficient, and can be extended by introducing a
microscopic model of the core.Comment: 10 pages, 8 figure
Approximate Bayesian inference for individual-based models with emergent dynamics
Individual-based models are used in a variety of scientific domains to study systems composed of multiple agents that interact
with one another and lead to complex emergent dynamics at the macroscale. A standard approach in the analysis of these systems is
to specify the microscale interaction rules in a simulation model, run simulations, and then qualitatively compare outputs to empirical
observations. Recently, more robust methods for inference for these types of models have been introduced, notably approximate Bayesian
computation, however major challenges remain due to the computational cost of simulations and the nonlinear nature of many complex
systems. Here, we compare two methods of approximate inference in a classic individual-based model of group dynamics with well-studied
nonlinear macroscale behaviour; we employ a Gaussian process accelerated ABC method with an approximated likelihood and with a
synthetic likelihood. We compare the accuracy of results when re-inferring parameters using a measure of macro-scale disorder (the
order parameter) as a summary statistic. Our findings reveal that for a canonical simple model of animal collective movement, parameter
inference is accurate and computationally efficient, even when the model is poised at the critical transition between order and disorder
Multimodal Shared-Control Interaction for Mobile Robots in AAL Environments
This dissertation investigates the design, development and implementation of cognitively adequate, safe and robust, spatially-related, multimodal interaction between human operators and mobile robots in Ambient Assisted Living environments both from the theoretical and practical perspectives. By focusing on different aspects of the concept Interaction, the essential contribution of this dissertation is divided into three main research packages; namely, Formal Interaction, Spatial Interaction and Multimodal Interaction in AAL. As the principle package, in Formal Interaction, research effort is dedicated to developing a formal language based interaction modelling and management solution process and a unified dialogue modelling approach. This package aims to enable a robust, flexible, and context-sensitive, yet formally controllable and tractable interaction. This type of interaction can be used to support the interaction management of any complex interactive systems, including the ones covered in the other two research packages. In the second research package, Spatial Interaction, a general qualitative spatial knowledge based multi-level conceptual model is developed and proposed. The goal is to support a spatially-related interaction in human-robot collaborative navigation. With a model-based computational framework, the proposed conceptual model has been implemented and integrated into a practical interactive system which has been evaluated by empirical studies. It has been particularly tested with respect to a set of high-level and model-based conceptual strategies for resolving the frequent spatially-related communication problems in human-robot interaction. Last but not least, in Multimodal Interaction in AAL, attention is drawn to design, development and implementation of multimodal interaction for elderly persons. In this elderly-friendly scenario, ageing-related characteristics are carefully considered for an effective and efficient interaction. Moreover, a standard model based empirical framework for evaluating multimodal interaction is provided. This framework was especially applied to evaluate a minutely developed and systematically improved elderly-friendly multimodal interactive system through a series of empirical studies with groups of elderly persons
Reverberation of pulsar wind nebulae (III): Modelling of the plasma interface empowering a long term radiative evolution
The vast majority of Pulsar Wind Nebulae (PWNe) present in the Galaxy is
formed by middle-aged systems characterized by a strong interaction of the PWN
itself with the supernova remnant (SNR). Unfortunately, modelling these systems
can be quite complex and numerically expensive, due to the non-linearity of the
PWN-SNR evolution even in the simple 1D / one-zone case when the reverse shock
of the SNR reaches the PWN, and the two begin to interact (and reverberation
starts).
Here we introduce a new numerical technique that couples the numerical
efficiency of the one-zone thin shell approach with the reliability of a full
``lagrangian'' evolution, able to correctly reproduce the PWN-SNR interaction
during the reverberation and to consistently evolve the particle spectrum
beyond. Based on our previous findings, we show that our novel strategy
resolves many of the uncertainties present in previous approaches, as the
arbitrariness in the SNR structure, and ensure a robust evolution, compatible
with results that can be obtained with more complex 1D dynamical approaches.
Our approach enable us for the first time to provide reliable spectral models
of the later compression phases in the evolution of PWNe. While in general we
found that the compression is less extreme than that obtained without such
detailed dynamical considerations, leading to the formation of less structured
spectral energy distributions, we still find that a non negligible fraction of
PWNe might experience a super-efficient phase, with the optical and/or X-ray
luminosity exceeding the spin-down one.Comment: 12 pages, 2 tables, 5 figure
A Decentralized Mobile Computing Network for Multi-Robot Systems Operations
Collective animal behaviors are paradigmatic examples of fully decentralized
operations involving complex collective computations such as collective turns
in flocks of birds or collective harvesting by ants. These systems offer a
unique source of inspiration for the development of fault-tolerant and
self-healing multi-robot systems capable of operating in dynamic environments.
Specifically, swarm robotics emerged and is significantly growing on these
premises. However, to date, most swarm robotics systems reported in the
literature involve basic computational tasks---averages and other algebraic
operations. In this paper, we introduce a novel Collective computing framework
based on the swarming paradigm, which exhibits the key innate features of
swarms: robustness, scalability and flexibility. Unlike Edge computing, the
proposed Collective computing framework is truly decentralized and does not
require user intervention or additional servers to sustain its operations. This
Collective computing framework is applied to the complex task of collective
mapping, in which multiple robots aim at cooperatively map a large area. Our
results confirm the effectiveness of the cooperative strategy, its robustness
to the loss of multiple units, as well as its scalability. Furthermore, the
topology of the interconnecting network is found to greatly influence the
performance of the collective action.Comment: Accepted for Publication in Proc. 9th IEEE Annual Ubiquitous
Computing, Electronics & Mobile Communication Conferenc
Energy-scales convergence for optimal and robust quantum transport in photosynthetic complexes
Underlying physical principles for the high efficiency of excitation energy
transfer in light-harvesting complexes are not fully understood. Notably, the
degree of robustness of these systems for transporting energy is not known
considering their realistic interactions with vibrational and radiative
environments within the surrounding solvent and scaffold proteins. In this
work, we employ an efficient technique to estimate energy transfer efficiency
of such complex excitonic systems. We observe that the dynamics of the
Fenna-Matthews-Olson (FMO) complex leads to optimal and robust energy transport
due to a convergence of energy scales among all important internal and external
parameters. In particular, we show that the FMO energy transfer efficiency is
optimum and stable with respect to the relevant parameters of environmental
interactions and Frenkel-exciton Hamiltonian including reorganization energy
, bath frequency cutoff , temperature , bath spatial
correlations, initial excitations, dissipation rate, trapping rate, disorders,
and dipole moments orientations. We identify the ratio of \lambda T/\gamma\*g
as a single key parameter governing quantum transport efficiency, where g is
the average excitonic energy gap.Comment: minor revisions, removing some figures, 19 pages, 19 figure
Efficient and robust entanglement generation in a many-particle system with resonant dipole-dipole interactions
We propose and discuss a scheme for robust and efficient generation of
many-particle entanglement in an ensemble of Rydberg atoms with resonant
dipole-dipole interactions. It is shown that in the limit of complete dipole
blocking, the system is isomorphic to a multimode Jaynes-Cummings model. While
dark-state population transfer is not capable of creating entanglement, other
adiabatic processes are identified that lead to complex, maximally entangled
states, such as the N-particle analog of the GHZ state in a few steps. The
process is robust, works for even and odd particle numbers and the
characteristic time for entanglement generation scales with N^a, with a being
less than unity.Comment: 4 figure
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