1,060 research outputs found
Differentiable Learning of Generalized Structured Matrices for Efficient Deep Neural Networks
This paper investigates efficient deep neural networks (DNNs) to replace
dense unstructured weight matrices with structured ones that possess desired
properties. The challenge arises because the optimal weight matrix structure in
popular neural network models is obscure in most cases and may vary from layer
to layer even in the same network. Prior structured matrices proposed for
efficient DNNs were mostly hand-crafted without a generalized framework to
systematically learn them. To address this issue, we propose a generalized and
differentiable framework to learn efficient structures of weight matrices by
gradient descent. We first define a new class of structured matrices that
covers a wide range of structured matrices in the literature by adjusting the
structural parameters. Then, the frequency-domain differentiable
parameterization scheme based on the Gaussian-Dirichlet kernel is adopted to
learn the structural parameters by proximal gradient descent. Finally, we
introduce an effective initialization method for the proposed scheme. Our
method learns efficient DNNs with structured matrices, achieving lower
complexity and/or higher performance than prior approaches that employ
low-rank, block-sparse, or block-low-rank matrices
Fast frequency discrimination and phoneme recognition using a biomimetic membrane coupled to a neural network
In the human ear, the basilar membrane plays a central role in sound
recognition. When excited by sound, this membrane responds with a
frequency-dependent displacement pattern that is detected and identified by the
auditory hair cells combined with the human neural system. Inspired by this
structure, we designed and fabricated an artificial membrane that produces a
spatial displacement pattern in response to an audible signal, which we used to
train a convolutional neural network (CNN). When trained with single frequency
tones, this system can unambiguously distinguish tones closely spaced in
frequency. When instead trained to recognize spoken vowels, this system
outperforms existing methods for phoneme recognition, including the discrete
Fourier transform (DFT), zoom FFT and chirp z-transform, especially when tested
in short time windows. This sound recognition scheme therefore promises
significant benefits in fast and accurate sound identification compared to
existing methods.Comment: 7 pages, 4 figure
Multi-Color Luminescence Transition of Upconversion Nanocrystals via Crystal Phase Control with SiO2 for High Temperature Thermal Labels
Upconversion nanocrystals (UCNs)-embedded microarchitectures with luminescence color transition capability and enhanced luminescence intensity under extreme conditions are suitable for developing a robust labeling system in a high-temperature thermal industrial process. However, most UCNs based labeling systems are limited by the loss of luminescence owing to the destruction of the crystalline phase or by a predetermined luminescence color without color transition capability. Herein, an unusual crystal phase transition of UCNs to a hexagonal apatite phase in the presence of SiO2 nanoparticles is reported with the enhancements of 130-fold green luminescence and 52-fold luminance as compared to that of the SiO2-free counterpart. By rationally combining this strategy with an additive color mixing method using a mask-less flow lithography technique, single to multiple luminescence color transition, scalable labeling systems with hidden letters-, and multi-luminescence colored microparticles are demonstrated for a UCNs luminescence color change-based high temperature labeling system
Growth Kinetics and Optical Properties of CsPbBr3 Perovskite Nanocrystals
We synthesized CsPbBr3 perovskite nanocrystals (NCs) at different reaction temperatures and tracked their growth kinetics on the basis of their optical properties and estimated size. The energies of the absorption and fluorescence (FL) peaks with increasing reaction temperature for the CsPbBr3 perovskite NCs were tuned within the regions of 2.429-2.570 eV and 2.391-2.469 eV, respectively, depending on size of the NCs (9.9-12.5 nm). The Stokes shifts of CsPbBr3 perovskite NCs with increasing NC size decreased from 101 meV to 38 meV. The full-width at half-maximum of the FL peaks for the CdSe NCs decreased from 150 meV to 90 meV because of the improved size uniformity of the CsPbBr3 perovskite NCs. The energy spacing of CsPbBr3 perovskite NCs synthesized at various reaction temperatures was calculated from Tauc plots; this information is critical for determining the bandgap energy and enables the size of the CsPbBr3 perovskite NCs to be estimated using the effective mass approximation
Evaluation of a Sodium–Water Reaction Event Caused by Steam Generator Tubes Break in the Prototype Generation IV Sodium-cooled Fast Reactor
AbstractThe prototype generation IV sodium-cooled fast reactor (PGSFR) has been developed by the Korea Atomic Energy Research Institute. This reactor uses sodium as a reactor coolant to transfer the core heat energy to the turbine. Sodium has chemical characteristics that allow it to violently react with materials such as a water or steam. When a sodium–water reaction (SWR) occurs due to leakage or breakage of steam generator tubes, high-pressure waves and corrosive reaction products are produced, which threaten the structural integrity of the components of the intermediate heat-transfer system (IHTS) and the safety of the primary heat-transfer system (PHTS). In the PGSFR, SWR events are included in the design-basis event. This event should be analyzed from the viewpoint of the integrities of the IHTS and fuel rods. To evaluate the integrity of the IHTS based on the consequences of the SWR, the behaviors of the generated high-pressure waves are analyzed at the major positions of a failed IHTS loop using a sodium–water advanced analysis method-II code. The integrity of the fuel rods must be consistently maintained below the safety acceptance criteria to avoid the consequences of the SWR. The integrity of the PHTS is evaluated using the multidimensional analysis of reactor safety-liquid metal reactor code to model the whole plant
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