Visualizing complexities: the human limits of air traffic control

Air traffic management is organized into filters in order to prevent tactical controllers from dealing with complex conflicting situations. In this article, we describe an experiment showing that a dynamic conflict display could improve human performance on complex conflict situations. Specifically, we designed a display tool that represents the conflicting portions of aircraft trajectories and the evolution of the conflict zone when the user adds a maneuver to an aircraft. The tool allows the user to dynamically check the potential conflicting zones with the computer mouse before making a maneuver decision. We tested its utility on a population of forty students: twenty air traffic controller (ATC) students at the end of their initial training and twenty engineering students with the same background but no ATC training. They had to solve conflicts involving 2–5 aircraft with a basic display and with the dynamic visualization tool. Results show that in easy situations (2 aircraft), performance is similar with both displays. However, as the complexity of the situations grows (from 3 to 5 aircraft), the dynamic visualization tool enables users to solve the conflicts more efficiently. Using the tool leads to fewer unsolved conflicts and shorter delays. No significant differences are found between the two test groups except for delays: ATC students give maneuvers that generate less delays than engineering students. These results suggest that humans are better able to manage complex situations with the help of our conflict visualization tool.     

Autonomous car decision making and trajectory tracking based on genetic algorithms and fractional potential fields

Intelligent Service Robotics - This article deals with the issue of trajectory optimization of autonomous terrestrial vehicles on a specific range handled by the human driver. The main...     

Effect of Anisotropic Microstructure on the Viscous Properties of an LTCC Material

The sintering behavior of a glass–ceramic (commercial material Ceramtape GC) was characterized using the discontinuous sinter-forging technique. The uniaxial viscosity E ^p and the viscous Poisson's ratio n^p of the composite body were determined as a function of density. Particular attention was paid to microstructural changes in order to quantify the anisotropy induced by load application. Pores and alumina particles were found to be both oriented perpendicular to the applied load direction. Finally, the experimental results were used to predict the value of the hydrostatic sintering stress.     

Strain heterogeneities and local anisotropy in crimped glass wool

A Digital Image Correlation method is used to study a compression test carried out on crimped glass wool samples to determine the displacement field, which reveals strain heterogeneities and further localization. The structure of the wool is locally strongly anisotropic, even though the preferential orientation varies significantly in space. This structure is analyzed using an ad hoc orientation detection tool. It is shown that the strain amplitude can be correlated with texture gradients for this type of material.     

HiperLAN 5.4-GHz low-power CMOS synchronous oscillator

A 5.4-GHz 0.25-μm very-large-scale-integration CMOS synchronous oscillator (SO) is proposed in this paper, which is designed to act as a local oscillator for HiperLAN systems. The advantage of using such an oscillator in a double-loop frequency synthesizer is demonstrated. The design strategy leading to an optimized SO with regards to its synchronization range is described. A test chip is presented, which provides a 150-MHz synchronization range and a -97-dBc/Hz phase noise at 10-kHz offset from the 5-GHz carrier, while consuming only 5 mA from a 2.5-V supply     

Robust sideslip angles observer for accurate off-road path tracking control

This paper proposes a control strategy to achieve high accurate path tracking in off-road conditions. The approach is based on adaptive and predictive techniques to account for sliding effects and actuator properties. An extended kinematic model is designed using sideslip angles definition. An observer is proposed to estimate online these variables, independently from the reference path and robot velocity. Thanks to the proposed approach, high accurate path tracking can then be achieved whatever the shape of the reference path and the task to be achieved (practical stabilization or moving object tracking).     

Numerical Implementation and Application of an Extended Model for Diffusion and Precipitation of Chemical Elements in Metallic Matrices

A model for simultaneous and coupled diffusion and precipitation of chemical elements in metallic matrices is proposed, together with a scheme for its numerical solution and some applications to problems of internal oxidation. This model extends over a previous one of the authors, which itself stood as a generalization of many earlier ones. It includes the possibility that precipitates may be present in large fractions; if so, they may affect diffusion in the matrix phase by acting as “barriers”, and/or by distorting this matrix. The possible re-dissolution of some or all precipitates may also be prohibited for kinetic reasons. A simple but robust numerical scheme based on 1D finite differences in space coupled with explicit integration in time is proposed to solve the equations of the problem. This scheme notably contains an efficient Newton–Raphson algorithm used to solve the laws of mass action. Numerical simulations of internal oxidation processes close to those encountered in actual industrial practice are finally presented. It is first shown that in simple cases, the simulations reproduce Wagner’s classical analytical solution and related ones. More complex cases not amenable to analytic solutions are then envisaged.     

An improved compact model for CMOS cross-shaped Hall-effect sensor including offset and temperature effects

A compact model of a cross-shaped horizontal integrated Hall-effect sensor is presented in this paper. Compared to existing models, reliability is improved, especially to simulate systems in which biasing and measurement circuits are not independent. The Hall device model core, already published, is based on a network of six non-linear resistances and four Hall voltage sources, and includes only 11 physical parameters. In this paper, in order to improve model predictivity, four additional parameters have been added to take the offset issue into account. In addition, variations of parameters with temperature are also addressed. The model is implemented in Verilog-A and has been validated through experiments carried out on Hall devices designed in a CMOS 0.35??m technology. The parameters extraction procedure is detailed and the maximum error between simulations and experimental data is less than 1?% for a wide range of biasing currents and temperatures.