Algorithm and Hardware Design of Discrete-Time Spiking Neural Networks Based on Back Propagation with Binary Activations

We present a new back propagation based training algorithm for discrete-time spiking neural networks (SNN). Inspired by recent deep learning algorithms on binarized neural networks, binary activation with a straight-through gradient estimator is used to model the leaky integrate-fire spiking neuron, overcoming the difficulty in training SNNs using back propagation. Two SNN training algorithms are proposed: (1) SNN with discontinuous integration, which is suitable for rate-coded input spikes, and (2) SNN with continuous integration, which is more general and can handle input spikes with temporal information. Neuromorphic hardware designed in 40nm CMOS exploits the spike sparsity and demonstrates high classification accuracy (>98% on MNIST) and low energy (48.4-773 nJ/image).Comment: 2017 IEEE Biomedical Circuits and Systems (BioCAS

CoBigICP: Robust and Precise Point Set Registration using Correntropy Metrics and Bidirectional Correspondence

In this paper, we propose a novel probabilistic variant of iterative closest point (ICP) dubbed as CoBigICP. The method leverages both local geometrical information and global noise characteristics. Locally, the 3D structure of both target and source clouds are incorporated into the objective function through bidirectional correspondence. Globally, error metric of correntropy is introduced as noise model to resist outliers. Importantly, the close resemblance between normal-distributions transform (NDT) and correntropy is revealed. To ease the minimization step, an on-manifold parameterization of the special Euclidean group is proposed. Extensive experiments validate that CoBigICP outperforms several well-known and state-of-the-art methods.Comment: 6 pages, 4 figures. Accepted to IROS202

Generating axial magnetic fields via two plasmon decay driven by a twisted laser

We propose a new way of axial magnetic fields generation in a non-relativistic laser intensity regime by using a twisted light carrying orbital angular momentum (OAM) to stimulate two-plasmon decay (TPD) in a plasma. The growth of TPD driven by an OAM light in a Laguerre-Gauss (LG) mode is investigated through three dimensional fluid simulations and theory. A theory based on the assumption that the electron plasma waves (EPWs) are locally driven by a number of local plane-wave lasers predicts the maximum growth rate proportional to the peak amplitude of the pump laser field and is verified by the simulations. The OAM conservation during its transportation from the laser to the TPD daughter EWPs is shown by both the theory and the simulations. The theory predicts generation of ~40T axial magnetic fields through the OAM absorption via TPD, which has perspective applications in the field of high energy density physics.Comment: 6 pages, 3 figures

Highly Dispersed Vanadia Anchored on Protonated g-C₃N₄ as an Efficient and Selective Catalyst for the Hydroxylation of Benzene into Phenol

The direct hydroxylation of benzene is a green and economical-efficient alternative to the existing cumene process for phenol production. However, the undesired phenol selectivity at high benzene conversion hinders its wide application. Here, we develop a one-pot synthesis of protonated g-C3N4 supporting vanadia catalysts (V-pg-C3N4) for the efficient and selective hydroxylation of benzene. Characterizations suggest that protonating g-C3N4 in diluted HCl can boost the generation of amino groups (NH/NH2) without changing the bulk structure. The content of surface amino groups, which determines the dispersion of vanadia, can be easily regulated by the amount of HCl added in the preparation. Increasing the content of surface amino groups benefits the dispersion of vanadia, which eventually leads to improved H2O2 activation and benzene hydroxylation. The optimal catalyst, V-pg-C3N4-0.46, achieves 60% benzene conversion and 99.7% phenol selectivity at 60 oC with H2O2 as the oxidant

Accelerated Photodegradation of Organic Pollutants over BiOBr/Protonated g-C₃N₄

Interfacial engineering has emerged as an effective strategy to optimize the photocatalytic activity of heterojunctions. Herein, the interface between graphitic carbon nitride (g-C3N4) and BiOBr was readily regulated by a protonation treatment. The synthesized BiOBr/g-C3N4 heterojunctions were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results show that pretreating g-C3N4 in diluted HCl solution led to a partial protonation of g-C3N4, which ensured intimate contact and high dispersion of supported BiOBr without changing the surface area, bulk g-C3N4 structure, or visible light absorption. The abundant BiOBr/g-C3N4 interfaces remarkably improved the separation and transfer of photogenerated carriers, which produced more h+ and O2●− to accelerate the photocatalytic degradation of organic pollutants. The photocatalytic activities of the BiOBr/g-C3N4 heterojunctions were evaluated by the degradation of RhB under visible-light irradiation (λ ≥ 420 nm). The apparent reaction (pseudo-first-order) rate constant of BiOBr supported on partially protonated g-C3N4 (Bpg-C3N4-0.75) is ca. 3-fold higher than that of BiOBr supported on pristine g-C3N4 (Bg-C3N4), verifying interfacial engineering as an effective strategy to optimize the catalytic activity of heterojunctions

Accelerated Photodegradation of Organic Pollutants over BiOBr/Protonated g-C3N4

Interfacial engineering has emerged as an effective strategy to optimize the photocatalytic activity of heterojunctions. Herein, the interface between graphitic carbon nitride (g-C3N4) and BiOBr was readily regulated by a protonation treatment. The synthesized BiOBr/g-C3N4 heterojunctions were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results show that pretreating g-C3N4 in diluted HCl solution led to a partial protonation of g-C3N4, which ensured intimate contact and high dispersion of supported BiOBr without changing the surface area, bulk g-C3N4 structure, or visible light absorption. The abundant BiOBr/g-C3N4 interfaces remarkably improved the separation and transfer of photogenerated carriers, which produced more h+ and O2●− to accelerate the photocatalytic degradation of organic pollutants. The photocatalytic activities of the BiOBr/g-C3N4 heterojunctions were evaluated by the degradation of RhB under visible-light irradiation (λ ≥ 420 nm). The apparent reaction (pseudo-first-order) rate constant of BiOBr supported on partially protonated g-C3N4 (Bpg-C3N4-0.75) is ca. 3-fold higher than that of BiOBr supported on pristine g-C3N4 (Bg-C3N4), verifying interfacial engineering as an effective strategy to optimize the catalytic activity of heterojunctions