Augmenting Deep Learning Performance in an Evidential Multiple Classifier System

International audienceThe main objective of this work is to study the applicability of ensemble methods in the context of deep learning with limited amounts of labeled data. We exploit an ensemble of neural networks derived using Monte Carlo dropout, along with an ensemble of SVM classifiers which owes its effectiveness to the hand-crafted features used as inputs and to an active learning procedure. In order to leverage each classifier's respective strengths, we combine them in an evidential framework, which models specifically their imprecision and uncertainty. The application we consider in order to illustrate the interest of our Multiple Classifier System is pedestrian detection in high-density crowds, which is ideally suited for its difficulty, cost of labeling and intrinsic imprecision of annotation data. We show that the fusion resulting from the effective modeling of uncertainty allows for performance improvement, and at the same time, for a deeper interpretation of the result in terms of commitment of the decision

CMOS Receiver Front-End Architecture for High-Speed SI-POF Links

This works presents a new CMOS analog front-end for short-reach high-speed optical communications which compensates the limited bandwidth of POF channels and is suitable for the required large area photodetectorf The proposed pseudo-differential architecture, formed by a preamplifier and an equalizer, has been designed in a standard 0.18-μm CMOS process with a 1-V supply voltage targeting gigabit transmission for NRZ modulation. The preamplifier is based on the flipped voltage follower stage to attain a very low input resistance in order to handle the large phodiode capacitance (3 pF). The equalizer can adjust the high-frequency boosting and the gain, to compensate for the variation of the characteristics of the channel due to length of the fiber, connections, etc. causing subtantial changes of the fiber bandwidth. Reliable electrical models are employed for a Mitsubishi GH SI-POF with 10-m to 50-m length and for a S5972 silicon photodiode from Hamamatsu suitable for such a fiber due to its large diameter (0.8 mm) and responsivity at 650 nm (0.44A/W). The bandwidth of the received signal can be enhanced from 100 MHz to 1.4 GHz and from 300 MHz to 1.4 GHz for a 50-m and 10-m POF respectively. The proposed circuit shows a transimpedance of 41.5 dBΩ while the theoretical sensitivity from noise performance is below -7.5 dBm with a BER = 10-12. The power consumption is below 16 mW from 1-V supply voltage. In conclusion it targets 1.25 Gbps through a 1-mm SI-POF up to 50-m length with a commercial Si PIN photodiode

Coulomb effects on the transport properties of quantum dots in strong magnetic field

We investigate the transport properties of quantum dots placed in strong magnetic field using a quantum-mechanical ' approach based on the 2D tight-binding Hamiltonian with direct Coulomb interaction and the Landauer-B\"{u}ttiker (LB) formalism. The electronic transmittance and the Hall resistance show Coulomb oscillations and also prove multiple addition processes. We identify this feature as the 'bunching' of electrons observed in recent experiments and give an elementary explanation in terms of spectral characteristics of the dot. The spatial distribution of the added electrons may distinguish between edge and bulk states and it has specific features for bunched electrons. The dependence of the charging energy on the number of electrons is discussed for strong and vanishing magnetic field. The crossover from the tunneling to quantum Hall regime is analyzed in terms of dot-lead coupling.Comment: 17 pages,8 figures,Revtex,submitted to Physical Review

High-sensitivity large-area photodiode read-out using a divide-and-conquer technique

In this letter, we present a novel technique to increase the sensitivity of optical read-out with large integrated photodiodes (PD). It consists of manufacturing the PD in several pieces, instead of a single device, and connecting a dedicated transimpedance amplifier (TIA) to each of these pieces. The output signals of the TIAs are combined, achieving a higher signal-to-noise ratio than with the traditional approach. This work shows a remarkable improvement in the sensitivity and transimpedance without the need for additional modifications or compensation techniques. As a result, an increase in sensitivity of 7.9 dBm and transimpedance of 8.7 dBO for the same bandwidth is achieved when dividing the photodiode read-out into 16 parallel paths. The proposed divide-and-conquer technique can be applied to any TIA design, and it is also independent of the core amplifier structure and fabrication process, which means it is compatible with every technology allowing the integration of PDs

Magnetization and Level Statistics at Quantum Hall Liquid-Insulator Transition in the Lattice Model

Statistics of level spacing and magnetization are studied for the phase diagram of the integer quantum Hall effect in a 2D finite lattice model with Anderson disorder.Comment: 4 pages, 6 figure

Application of a flipped classroom for model-based learning in electronics

This paper investigates the effectiveness of the flipped classroom methodology to build conceptual knowledge mentalmodels. In particular, it examines the learning process and outcomes of 40 students of a course on Physical Electronics inthe last year of a bachelor’s degree program in Physics, for which specific educational resources have been developed toimplement the flipped classroom. Among them, non-interactive resources are better to present topics and ideas, whereasinteractive resources are more useful to establish links between them to build and check the models. The examined dataentail grades, laboratory reports and rubrics, outcomes of learning activities, and direct observation, showing that theflipped classroom improves the construction of mental models, providing teaching resources where the topics and mainideas are presented, developed and exercised, and allowing students to establish links to build and check the models.Furthermore, this strategy increases the personal commitment of the students, fostering autonomy and cooperation withpeers, all of which makes it an effective pedagogical tool to build knowledge mental models

ICT-based didactic strategies to build knowledge models in electronics in higher education

This paper presents a didactic strategy based on information and communication technologies (ICTs) to help students build knowledge mental models in the context of Higher Education. It presents a methodology that combines the flipped classroom with other active methodologies and traditional lessons to improve the teaching/learning process of Electronics in university studies in Physics. Using the flipped classroom as the main strategy, the proposed methodology allows devoting more classroom time to active learning so that the instructor can follow the student learning process and evaluate model construction, while at the same time it increases student implication and fosters autonomy and cooperation with peers, contributing to a better construction of knowledge mental models in Electronics

Radio over fiber: An alternative broadband network technology for Iot

Wireless broadband access networks have been positioning themselves as a good solution for manufacturers and users of IoT (internet of things) devices, due mainly to the high data transfer rate required over terminal devices without restriction of information format. In this work, a review of two Radio over Fiber strategies is presented. Both have excellent performance and even offer the possibility to extend wireless area coverage where mobile networks do not reach or the 802.11 network presents issues. Radio Frequency over Fiber (RFoF) and intermediate Frequency over Fiber (IFoF) are two transmission strategies compatible with the required new broadband services and both play a key role in the design of the next generation integrated optical–wireless networks, such as 5G and Satcom networks, including on RAU (Remote Antenna Unit) new functionalities to improve their physical dimensions, employing a microelectronic layout over nanometric technologies

Programmable low-power low-noise capacitance to voltage converter for MEMS accelerometers

In this work, we present a capacitance-to-voltage converter (CVC) for capacitive accelerometers based on microelectromechanical systems (MEMS). Based on a fully-differential transimpedance amplifier (TIA), it features a 34-dB transimpedance gain control and over one decade programmable bandwidth, from 75 kHz to 1.2 MHz. The TIA is aimed for low-cost low-power capacitive sensor applications. It has been designed in a standard 0.18-µm CMOS technology and its power consumption is only 54 µW. At the maximum transimpedance configuration, the TIA shows an equivalent input noise of 42 fA/vHz at 50 kHz, which corresponds to 100 µg/vHz

Resonant and coherent transport through Aharonov-Bohm interferometers with coupled quantum dots

A detailed description of the tunneling processes within Aharonov-Bohm (AB) rings containing two-dimensional quantum dots is presented. We show that the electronic propagation through the interferometer is controlled by the spectral properties of the embedded dots and by their coupling with the ring. The transmittance of the interferometer is computed by the Landauer-B\"uttiker formula. Numerical results are presented for an AB interferometer containing two coupled dots. The charging diagrams for a double-dot interferometer and the Aharonov Bohm oscillations are obtained, in agreement with the recent experimental results of Holleitner {\it et al}. [Phys. Rev. Lett. {\bf 87}, 256802 (2001)] We identify conditions in which the system shows Fano line shapes. The direction of the asymetric tail depends on the capacitive coupling and on the magnetic field. We discuss our results in connection with the experiments of Kobayashi {\it et al} [Phys. Rev. Lett. {\bf 88}, 256806 (2002)] in the case of a single dot.Comment: 30 pages, 12 figure