1,720,983 research outputs found
The Pulsed Laser Ablation Deposition Technique: A New Deposition Configuration for the Synthesis of Uniform Films
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Neuromorphic valence and arousal estimation
No full textRecognizing faces and their underlying emotions is an important aspect of biometrics. In fact, estimating emotional states from faces has been tackled from several angles in the literature. In this paper, we follow the novel route of using neuromorphic data to predict valence and arousal values from faces. Due to the difficulty of gathering event-based annotated videos, we leverage an event camera simulator to create the neuromorphic counterpart of an existing RGB dataset. We demonstrate that not only training models on simulated data can still yield state-of-the-art results in valence-arousal estimation, but also that our trained models can be directly applied to real data without further training to address the downstream task of emotion recognition. In the paper we propose several alternative models to solve the task, both frame-based and video-based
Detailed studies of photocathodes based on Y thin films grown by PLD technique
No full textThe effects of laser fluence on the morphology of Y films in the regime characteristic of multiple-pulse laser deposition were investigated. Y thin films were deposited on Silicon and Copper substrates. The samples deposited on Silicon substrate were used to deduce the morphology and the thickness of the deposited films. On the contrary, the samples deposited on Copper substrate were tested as photocathodes in a DC photodiode cell. The interest to produce Y-based photocathodes is due to the low work function of this metal with the possibility to drive such photocathodes with a visible radiation in the radio-frequency photo-injector. In this way it is possible to reduce the thermal emittance of the photoelectron beam and to increase the photocurrent intensity by utilizing the second harmonic of Ti:Sa driver laser. The quantum efficiency was measured for the first time by using a visible CW laser diode emitting at 406 nm
Droplet distribution from melt displacement and ejection mechanism during Al ns-laser ablation and deposition experiments: Influence of laser spot position
No full textAddressing Limitations of State-Aware Imitation Learning for Autonomous Driving
Get PDFConditional Imitation learning is a common and effective approach to train autonomous driving agents. However, two issues limit the full potential of this approach: (i) the inertia problem, a special case of causal confusion where the agent mistakenly correlates low speed with no acceleration, and (ii) low correlation between offline and online performance due to the accumulation of small errors that brings the agent in a previously unseen state. Both issues are critical for state-aware models, yet informing the driving agent of its internal state as well as the state of the environment is of crucial importance. In this paper we propose a multi-task learning agent based on a multi-stage vision transformer with state token propagation. We feed the state of the vehicle along with the representation of the environment as a special token of the transformer and propagate it throughout the network. This allows us to tackle the aforementioned issues from different angles: guiding the driving policy with learned stop/go information, performing data augmentation directly on the state of the vehicle and visually explaining the model's decisions. We report a drastic decrease in inertia and a high correlation between offline and online metrics
“Mg-based photocathodes prepared by ns, ps and fs PLD for the production of high brightness electron beams”
No full textMg-based films have been prepared by pulsed laser deposition technique for photocathode applications. We have investigated the influence of pulse laser duration on morphology and photoemissive properties. Two laser sources have been used, generating pulses of 30 ns at 308 nm (XeCl excimer laser), 5 ps and 500 fs at 248 nm (KrF excimer laser ) to grow Mg films onto Si and Cu substrates in high vacuum (~ 10-7 Pa) and at room temperature. Morphological investigations carried out by Scanning Electron Microscopy (SEM) have revealed that, in our experimental conditions, the number and the mean size of the droplets on the films surfaces decreases as the pulse laser duration shortens. The contamination level of Mg film surfaces have been studied by Energy Dispersive X-ray spectroscopy (EDX). The photoelectron performances in terms of quantum efficiency (QE) and emission stability have been tested in a UHV DC photodiode cell (10-7 Pa). Measures of the QE of the samples surfaces have revealed a decrease on the initial value for Mg-based photocathodes prepared by fs laser (from 7.8x10-4 to 6.6x10-4 ) PLD with respect to ps ( from 6.2x10-4 to 7.4x10-4 ) and ns lasers (from 5.0x10-4 to 1.6x10-3). A comparison among Mg-based photocathodes prepared by ns, ps and fs PLD for the production of high brightness electron beams has been presented and discusse
Spike-TBR: A noise resilient neuromorphic event representation
Get PDFEvent cameras offer significant advantages over traditional frame-based sensors, including higher temporal resolution, lower latency and dynamic range. However, efficiently converting event streams into formats compatible with standard computer vision pipelines remains a challenging problem, particularly in the presence of noise. In this paper, we propose Spike-TBR, a novel event-based encoding strategy based on Temporal Binary Representation (TBR), addressing its vulnerability to noise by integrating spiking neurons. Spike-TBR combines the frame-based advantages of TBR with the noise-filtering capabilities of spiking neural networks, creating a more robust representation of event streams. We evaluate four variants of Spike-TBR, each using different spiking neurons, across multiple datasets, demonstrating superior performance in noise-affected scenarios while improving the results on clean data. Our method bridges the gap between spike-based and frame-based processing, offering a simple noise-resilient solution for event-driven vision applications
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