On the Practical Limitations for the Generation of Gunn Oscillations in Highly Doped GaN Diodes

Planar Gunn diodes based on doped GaN active layers with different geometries have been fabricated and characterized. Gunn oscillations have not been observed due to the catastrophic breakdown of the diodes for applied voltages around 20-25 V, much below the bias theoretically needed for the onset of Gunn oscillations. The breakdown of the diodes has been analyzed by pulsed I-V measurements at low temperature, and it has been observed to be almost independent of the geometry of the channels, thus allowing to discard self-heating effects as the origin of the device burning. The other possible mechanism for the device failure is impact-ionization avalanche due to the high electric fields present at the anode corner of the isolating trenches. However, Monte Carlo simulations using the typical value of the intervalley energy separation of GaN, ε_(1-2)=2.2 eV, show that impact ionization mechanisms are not significant for the voltages for which the experimental failure is observed. But recent experiments showed that ε_(1-2) is lower, around 0.9 eV. This lower intervalley separation leads to a much lower threshold voltage for the Gunn oscillations, not far from the experimental breakdown. Therefore, we attribute the devices failure to an avalanche process just when Gunn domains start to form, since they increase the population of electrons at the high electric field region, thus strongly enhancing impact ionization mechanisms which lead to the diode failure

INSPEX: Make environment perception available as a portable system

International audienceObstacle avoidance systems for autonomous vehicles combine multiple sensing technologies (i.e. LiDAR, Radar, Ultrasound and Visual) to detect different types of obstacles across the full range of lighting and weather conditions. Sensor data are fused with vehicle orientation (obtained for instance from an Inertial Measurement Unit and/or compass) and navigation subsystems. Power hungry, they require powerful computational capability, which limits their use to high-end vehicles and robots. 2 INSPEX ambition The H2020 INSPEX project plans to make obstacle detection capabilities available as a personal portable multi-sensors, miniaturised, low power device. This device will detect, locate and warn of obstacles under different environmental conditions, in indoor/outdoor environments, with static and mobile obstacles. Potential applications range from safer human navigation in reduced visibility conditions (e.g. for first responders and fire brigades), small robot/drone obstacle avoidance systems to navigation for the visually and mobility impaired people. As primary demonstrator (Fig.1), we will plug the INSPEX device on a white cane (see Fig. 1) for Visually Impaired and Blind (VIB) people to detect obstacle over the whole person height, provide audio feedback about harmful obstacles, improve their mobility confidence and reduce injuries, especially at waist and head levels [1]. The device will offer a "safety cocoon" to its user

Towards a portable smart spatial exploration system for environment perception

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SARMENTI: Smart multisensor embedded and secure system for soil nutrient and gaseous emission monitoring

Demand for sustainably produced food is driving current strategies for intensification of the agricultural sector worldwide. To meet these challenges farmers will need to adopt a whole-farm approach to resource efficiency. They will increase their productivity with a better application of knowledge per hectare. Optimising soil fertility will enable farmers to maximise their productivity and profitability with higher grass and crop yield and quality

INSPEX: design and integration of a portable/wearable smart spatial exploration system

The INSPEX H2020 project main objective is to integrate automotive-equivalent spatial exploration and obstacle detection functionalities into a portable/wearable multi-sensor, miniaturised, low power device. The INSPEX system will detect and localise in real-time static and mobile obstacles under various environmental conditions in 3D. Potential applications range from safer human navigation in reduced visibility, small robot/drone obstacle avoidance systems to navigation for the visually/mobility impaired, this latter being the primary use-case considered in the project

INSPEX: Make environment perception available as a portable system

Obstacle avoidance systems for autonomous vehicles combine multiple sensing technologies (i.e. LiDAR, Radar, Ultrasound and Visual) to detect different types of obstacles across the full range of lighting and weather conditions. Sensor data are fused with vehicle orientation (obtained for instance from an Inertial Measurement Unit and/or compass) and navigation subsystems. Power hungry, they require powerful computational capability, which limits their use to high-end vehicles and robots

Use of protein rich peas in the rabbit

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Evaluation and mitigation of aging effects on a digital on-chip voltage and temperature sensor

Conference of 25th International Workshop on Power and Timing Modeling, Optimization and Simulation, PATMOS 2015 ; Conference Date: 1 September 2015 Through 4 September 2015; Conference Code:117722International audiencePower efficiency is a tremendous challenge for high performance embedded systems under energy constraints. Fine grain Dynamic Voltage and Frequency Scaling approaches are usually implemented in order to meet these conflicting objectives. Moreover, these techniques can be improved if local and on-the-fly monitoring of the dynamic variations is performed. A low-cost onchip general purpose sensor associated with an appropriate data fusion technique has been recently developed in order to monitor local temperature and voltage conditions. However, reliability has become a major concern as the technology scales below 40nm. The aging variation is not anymore negligible and must be taken into account during the monitor design and operation. This paper revisits such a sensor under both BTI and HCI aging effects in 28nm STMicroelectronics technology. A simple recalibration method is also proposed to mitigate the aging effects on the VT estimation