208 research outputs found

    Agent Behaviour Simulator (ABS):a platform for urban behaviour development

    Get PDF
    Computer Graphics have become important for many applicationsand the quality of the produced images have greatly improved. Oneof the interesting remaining problems is the representation of densedynamic environments such as populated cities. Although recentlywe saw some successfulwork on the rendering such environments,the real?time simulation of virtual cities populated by thousands ofintelligent animated agents is still very challenging.In this paperwe describe a platformthat aims to accelerate the developmentof agent behaviours. The platform makes it easy to enterlocal rules and callbacks which govern the individual behaviours.It automatically performs the routine tasks such as collision detectionallowing the user to concentrate on defining the more involvedtasks. The platform is based on a 2D-grid with a four-layered structure.The two first layers are used to compute the collision detectionagainst the environment and other agents and the last two are usedfor more complex behaviours.A set of visualisation tools is incorporated that allows the testingof the real?time simulation. The choices made for the visualisationallow the user to better understand the way agents move inside theworld and how they take decisions, so that the user can evaluate ifit simulates the expected behaviour.Experimentation with the system has shown that behaviours inenvironments with thousands of agents can be developed and visualisedin effortlessly

    Real-time shadows for animated crowds in virtual cities

    Get PDF

    Mobile phone-based joint angle measurement for functional assessment and rehabilitation of proprioception

    Get PDF
    International audienceAssessment of joint functional and proprioceptive abilities is essential for balance, posture, and motor control rehabilitation. Joint functional ability refers to the capacity of movement of the joint. It may be evaluated thereby measuring the joint range of motion (ROM). Proprioception can be defined as the perception of the position and of the movement of various body parts in space. Its role is essential in sensorimotor control for movement acuity, joint stability, coordination, and balance. Its clinical evaluation is commonly based on the assessment of the joint position sense (JPS). Both ROM and JPS measurements require estimating angles through goniometer, scoliometer, laser-pointer, and bubble or digital inclinometer. With the arrival of Smartphones, these costly clinical tools tend to be replaced. Beyond evaluation, maintaining and/or improving joint functional and proprioceptive abilities by training with physical therapy is important for long-term management. This review aims to report Smartphone applications used for measuring and improving functional and proprioceptive abilities. It identifies that Smartphone applications are reliable for clinical measurements and are mainly used to assess ROM and JPS. However, there is lack of studies on Smartphone applications which can be used in an autonomous way to provide physical therapy exercises at home

    iBalance-ABF: a Smartphone-Based Audio-Biofeedback Balance System

    Get PDF
    International audienceThis article proposes an implementation of a Kalman Filter, using inertial sensors of a Smartphone, to estimate 3D angulation of the trunk. The developped system monitors the trunk angular evolution during bipedal stance and helps the user to improve balance through a configurable and integrated auditory-biofeedback loop. A proof-of-concept study was performed to assess the effectiveness of this so-called iBalance-ABF - smartphone-based audio-biofeedback system - in improving balance during bipedal standing. Results showed that young healthy individuals were able to efficiently use ABF on sagittal trunk tilt to improve their balance in the ML direction. These findings suggest that iBalance-ABF system as a Telerehabilitation system which could represent a suitable solution for Ambient Assisted Living technologies

    Hollow Y zeolite single crystals: synthesis, characterization and activity in the hydroisomerization of n-hexadecane

    Get PDF
    International audienceHollow Y zeolite single crystals have been obtained from a conventional NaY zeolite following a three-step process involving a severe dealumination of the zeolite with silicon tetrachloride (step #1), followed by an acid washing under mild conditions (step #2) and finally a selective dissolution of the crystals core in the presence of protective Al species (step #3). Crystals are characterized by the presence of a regular internal cavity with 0.1–0.2 nm thick microporous walls. They contain a relatively low framework Al content but significant amounts of extraframework Al oxide species mainly located on the external surface of the crystals. Hollow crystals have been mixed with a Pt-supported alumina binder and used as catalysts in the hydroisomerization of n-hexadecane. Compared to the corresponding bulk crystals obtained after step #2, their higher activity has been attributed to a better efficiency, directly resulting from the presence of the cavity

    Stochasticity of Pores Interconnectivity in Li–O2 Batteries and its Impact on the Variations in Electrochemical Performance

    Get PDF
    While large dispersions in electrochemical performance have been reported for lithium oxygen batteries in the literature, they have not been investigated in any depth. The variability in the results is often assumed to arise from differences in cell design, electrode structure, handling and cell preparation at different times. An accurate theoretical framework turns out to be needed to get a better insight into the mechanisms underneath and to interpret experimental results. Here, we develop and use a pore network model to simulate the electrochemical performance of three-dimensionally resolved lithium−oxygen cathode mesostructures obtained from TXM nanocomputed tomography. We apply this model to the 3D reconstructed object of a Super P carbon electrode and calculate discharge curves, using identical conditions, for four different zones in the electrode and their reversed configurations. The resulting galvanostatic discharge curves show some dispersion, (both in terms of capacity and overpotential) which we attribute to the way pores are connected with each other. Based on these results, we propose that the stochastic nature of pores interconnectivity and the microscopic arrangement of pores can lead, at least partially, to the variations in electrochemical results observed experimentally

    Hollow Y zeolite single crystals: synthesis, characterization and activity in the hydroisomerization of n-hexadecane

    Get PDF
    Hollow Y zeolite single crystals have been obtained from a conventional NaY zeolite following a three-step process involving a severe dealumination of the zeolite with silicon tetrachloride (step #1), followed by an acid washing under mild conditions (step #2) and finally a selective dissolution of the crystals core in the presence of protective Al species (step #3). Crystals are characterized by the presence of a regular internal cavity with 0.1–0.2 nm thick microporous walls. They contain a relatively low framework Al content but significant amounts of extraframework Al oxide species mainly located on the external surface of the crystals. Hollow crystals have been mixed with a Pt-supported alumina binder and used as catalysts in the hydroisomerization of n-hexadecane. Compared to the corresponding bulk crystals obtained after step #2, their higher activity has been attributed to a better efficiency, directly resulting from the presence of the cavity

    Text mining assisted review of the literature on Li-O2 batteries

    Get PDF
    The high theoretical capacity of Li-O2 batteries attracts a lot of attention and this field has expanded significantly in the last two decades. In a more general way, the large number of articles being published daily makes it difficult for researchers to keep track of the progress in science. Here we develop a text mining program in an attempt to facilitate the process of reviewing the literature published in a scientific field and apply it to Li-O2 batteries. We analyze over 1800 articles and use the text mining program to extract reported discharge capacities, for the first time, which allows us to show the clear progress made in recent years. In this paper, we focus on three main challenges of Li-O2 batteries, namely the stability-cyclability, the low practical capacity and the rate capability. Indeed, according to our text mining program, articles dealing with these issues represent 86% of the literature published in the field. For each topic, we provide a bibliometric analysis of the literature before focusing on a few key articles which allow us to get insights into the physics and chemistry of such systems. We believe that text mining can help readers find breakthrough papers in a field (e.g. by identifying papers reporting much higher performances) and follow the developments made at the state of the art (e.g. by showing trends in the numbers of papers published—a decline in a given topic probably being the sign of limitations). With the progress of text mining algorithms in the future, the process of reviewing a scientific field is likely to become more and more automated, making it easier for researchers to get the 'big picture' in an unfamiliar scientific field

    Importance of Incorporating Explicit 3D-Resolved Electrode Mesostructures in Li–O2 Battery Models

    Get PDF
    Lithium-oxygen batteries are attractive for reversible energy storage because of their theoretically high capacities. Practically, high capacities are challenging to achieve due to key issues such as the transport and growth of the Li2O2 discharge product. Numerous carbon-based cathode mesostructures have been studied experimentally and computationally aiming to reach higher capacities. One-dimensional continuum models are widely used to study the discharge capacities of electrode mesostructures. Here, we investigate the capabilities and shortcomings of such models to represent different electrode mesostructures, Li2O2 growth mechanisms, and their impact on the discharge performance by comparing them to pore network models which consider an explicit representation of the three-dimensional pore mesostructure. The continuum model can accurately predict discharge capacities when the discharge products grow through surface mechanism, but fails to provide reasonable results when this growth includes a solution mechanism. Conversely, the pore network model results are in agreement with experiments. We attribute the better accuracy of the pore network model to a more accurate representation of the electrode mesostructures, particularly the explicit consideration of the pore interconnectivity. The pore network model allows us to reconcile, within a single theoretical framework, the scattered correlations between discharge capacity and electrode mesostructure descriptors reported in the literature

    Standard survey methods for estimating colony losses and explanatory risk factors in Apis mellifera

    Get PDF
    This chapter addresses survey methodology and questionnaire design for the collection of data pertaining to estimation of honey bee colony loss rates and identification of risk factors for colony loss. Sources of error in surveys are described. Advantages and disadvantages of different random and non-random sampling strategies and different modes of data collection are presented to enable the researcher to make an informed choice. We discuss survey and questionnaire methodology in some detail, for the purpose of raising awareness of issues to be considered during the survey design stage in order to minimise error and bias in the results. Aspects of survey design are illustrated using surveys in Scotland. Part of a standardized questionnaire is given as a further example, developed by the COLOSS working group for Monitoring and Diagnosis. Approaches to data analysis are described, focussing on estimation of loss rates. Dutch monitoring data from 2012 were used for an example of a statistical analysis with the public domain R software. We demonstrate the estimation of the overall proportion of losses and corresponding confidence interval using a quasi-binomial model to account for extra-binomial variation. We also illustrate generalized linear model fitting when incorporating a single risk factor, and derivation of relevant confidence intervals
    corecore