Risk-informed decision-making in the presence of epistemic uncertainty

International audienceAn important issue in risk analysis is the distinction between epistemic and aleatory uncertainties. In this paper, the use of distinct representation formats for aleatory and epistemic uncertainties is advocated, the latter being modelled by sets of possible values. Modern uncertainty theories based on convex sets of probabilities are known to be instrumental for hybrid representations where aleatory and epistemic components of uncertainty remain distinct. Simple uncertainty representation techniques based on fuzzy intervals and p-boxes are used in practice. This paper outlines a risk analysis methodology from elicitation of knowledge about parameters to decision. It proposes an elicitation methodology where the chosen representation format depends on the nature and the amount of available information. Uncertainty propagation methods then blend Monte-Carlo simulation and interval analysis techniques. Nevertheless, results provided by these techniques, often in terms of probability intervals, may be too complex to interpret for a decision-maker and we therefore propose to compute a unique indicator of the likelihood of risk, called confidence index. It explicitly accounts for the decision-maker's attitude in the face of ambiguity. This step takes place at the end of the risk analysis process, when no further collection of evidence is possible that might reduce the ambiguity due to epistemic uncertainty. This last feature stands in contrast with the Bayesian methodology, where epistemic uncertainties on input parameters are modelled by single subjective probabilities at the beginning of the risk analysis process

A Programmable Vision Chip with High Speed Image Processing

International audienceA high speed Analog VLSI Image acquisition and pre-processing system is described in this paper. A 64×64 pixel retina is used to extract the magnitude and direction of spatial gradients from images. So, the sensor implements some low-level image processing in a massively parallel strategy in each pixel of the sensor. Spatial gradients, various convolutions as Sobel filter or Laplacian are described and implemented on the circuit. The retina implements in a massively parallel way, at pixel level, some various treatments based on a four-quadrants multipliers architecture. Each pixel includes a photodiode, an amplifier, two storage capacitors and an analog arithmetic unit. A maximal output frame rate of about 10000 frames per second with only image acquisition and 2000 to 5000 frames per second with image processing is achieved in a 0.35 μm standard CMOS process. The retina provides address-event coded output on three asynchronous buses, one output is dedicated to the gradient and both other to the pixel values. A prototype based on this principle, has been designed. Simulation results from Mentor GraphicsTMsoftware and AustriaMicrosystem Design kit are presented

Cost-Utility Analysis: Current Methodological Issues and Future Perspectives

The use of cost–effectiveness as final criterion in the reimbursement process for listing of new pharmaceuticals can be questioned from a scientific and policy point of view. There is a lack of consensus on main methodological issues and consequently we may question the appropriateness of the use of cost–effectiveness data in health care decision-making. Another concern is the appropriateness of the selection and use of an incremental cost–effectiveness threshold (Cost/QALY). In this review, we focus mainly on only some key methodological concerns relating to discounting, the utility concept, cost assessment, and modeling methodologies. Finally we will consider the relevance of some other important decision criteria, like social values and equity

MASL: a Language for Multi-Agent System

The classical approach for Multi-Agent System (MAS) Control, especially autonomous and robotic ones, deals first from a microscopic point of view: each agent embed a control program with communication/synchronization primitives that enable cooperation between agents. The emergence of a global behaviour from a macroscopic point of view can only be observed afterwards. In this context, MASL offers a macroscopic and unified approach with heterogeneous and distributed calculations over deliberative, reactive or hybrid agents. In this high level language, regardless of the runtime, each concurrent agent locally decides its participation in a collective execution block named an e-block. Each e-block is an anonymous collective program that runs over an agent network following local conditions. The orchestral mode (scalar, asynchronous, synchronous) is statically fixed by a shared block attribute. The communication use shared memory, events, synchronous messages passing, and asynchronous messages passing. Heterogeneous agents are managed with heritage and polymorphism. Permeability mechanism, dealing with agent autonomy, allows an agent to dynamically filter calls to its interface in respects to the sender position in the e-block hierarchy. In dynamic task allocation of agents, auto failover and recovery, agent replacement in a robot fleet (case of agent failure, loss of a mandatory functionality for the mission) an e-block is an entry point of a collaborative work. In the case of synchronous e-block, the programming paradigm is the data parallel model with iterative task for waves of agents. Finally, MASL offers advances in the field of MAS (dynamic belonging to groups, accuracy of the pace of actions to undertake to enable a desired cooperation) and for the management of errors

A high speed programmable focal-plane SIMD vision chip. Analog Integrated Circuits and Signal Processing

International audienceA high speed analog VLSI image acquisition and low-level image processing system is presented. The architecture of the chip is based on a dynamically reconfigurable SIMD processor array. The chip features a massively parallel architecture enabling the computation of programmable mask-based image processing in each pixel. Each pixel include a photodiode, an amplifier, two storage capacitors, and an analog arithmetic unit based on a four-quadrant multiplier architecture. A 64 × 64 pixel proof-of-concept chip was fabricated in a 0.35 μm standard CMOS process, with a pixel size of 35 μm × 35 μm. The chip can capture raw images up to 10,000 fps and runs low-level image processing at a framerate of 2,000–5,000 fp

A 10 000 fps CMOS Sensor With Massively Parallel Image Processing

International audienceA high-speed analog VLSI image acquisition and preprocessing system has been designed and fabricated in a 0.35 standard CMOS process. The chip features a massively parallel architecture enabling the computation of programmable low-level image processing in each pixel. Extraction of spatial gradients and convolutions such as Sobel or Laplacian filters are implemented on the circuit. Measured results show that the proposed sensor successfully captures raw images up to 10 000 frames per second and runs low-level image processing at a frame rate of 2000 to 5000 frames per second

Vibrotactile guidance for trajectory following in computer aided surgery.

International audienceMost conventional computer-aided navigation systems assist the surgeon visually by tracking the position of an ancillary and by superposing this position into the 3D preoperative imaging exam. This paper aims at adding to such navigation systems a device that will guide the surgeon towards the target, following a complex preplanned ancillary trajectory. We propose to use tactile stimuli for such guidance, with the design of a vibrating belt. An experiment using a virtual surgery simulator in the case of skull base surgery is conducted with 9 naïve subjects, assessing the vibrotactile guidance effectiveness for complex trajectories. Comparisons between a visual guidance and a visual+tactile guidance are encouraging, supporting the relevance of such tactile guidance paradigm