Hyperparameter on-line learning of stochastic resonance based threshold networks

Aiming at training the feed-forward threshold neural network consisting of nondifferentiable activation functions, the approach of noise injection forms a stochastic resonance based threshold network that can be optimized by various gradient-based optimizers. The introduction of injected noise extends the noise level into the parameter space of the designed threshold network, but leads to a highly non-convex optimization landscape of the loss function. Thus, the hyperparameter on-line learning procedure with respective to network weights and noise levels becomes of challenge. It is shown that the Adam optimizer, as an adaptive variant of stochastic gradient descent, manifests its superior learning ability in training the stochastic resonance based threshold network effectively. Experimental results demonstrate the significant improvement of performance of the designed threshold network trained by the Adam optimizer for function approximation and image classification.     

The single-polarization filter composed of gold-coated photonic crystal fiber

A single-polarization filter comprising a gold-coated photonic crystal fiber based on surface plasmon resonance is designed and investigated. The pattern matching and coupled polarization characteristics analyzed by the full-vector finite element method (FEM) and losses at 1,540 nm are achieved to 1,016.01739 dB/cm (x-pol core mode) and 33.81917 dB/cm (y-pol core mode). The crosstalk (CT) value of the 1,540 nm band is ?853.12653 dB for fiber length $L=1,000\mathrm{\mu }\text{m}$ and the bandwidth is 850 nm. The working wavelength of the filter ranges from 1,280 nm to 1,540 nm by varying the diameter of outer air holes ($d_1$), the diameter of inner air holes ($d_4$), the metal film thickness (t), as well as the liquid refractive index (n).     

Enhancing signal-to-noise ratio and resolution in low-field NMR relaxation measurements using post-acquisition digital filters

The traditional way to enhance signal-to-noise ratio (SNR) of nuclear magnetic resonance (NMR) signals is to increase the number of scans. However, this procedure increases the measuring time that can be prohibitive for some applications. Therefore, we have tested the use of several post-acquisition digital filters to enhance SNR up to one order of magnitude in time domain NMR (TD-NMR) relaxation measurements. The procedures were studied using continuous wave free precession (CWFP-T₁) signals, acquired with very low flip angles that contain six times more noise than the Carr–Purcell–Meiboom–Gill (CPMG) signal of the same sample and experimental time. Linear (LI) and logarithmic (LO) data compression, low-pass infinity impulse response (LP), Savitzky–Golay (SG), and wavelet transform (WA) post-acquisition filters enhanced the SNR of the CWFP-T₁ signals by at least six times. The best filters were LO, SG, and WA that have high enhancement in SNR without significant distortions in the ILT relaxation distribution data. Therefore, it was demonstrated that these post-acquisition digital filters could be a useful way to denoise CWFP-T₁, as well as CPMG noisy signals, and consequently reducing the experimental time. It was also demonstrated that filtered CWFP-T₁ method has the potential to be a rapid and nondestructive method to measure fat content in beef and certainly in other meat samples.     

Notch Effect and Frequency Compensation of Dual-Sensor OBC Data in Shallow Water

Reverberation is significant in shallow water and produces obvious notches in OBC spec-tra. It also degrades the quality of sections and increases the difficulty of processing and interpretation. This ...     

过滤机液位控制系统在洗煤厂的应用

介绍了过滤机液位控制系统的结构、功能及其在洗煤厂的应用情况，并根据其运行结果，指出了需改进的部分。     

燃料添加剂对柴油机烟粒燃烧的影响

考察了燃料添加剂对降低柴油机烟粒燃点温度的效应。含金属添加剂的柴油机烟粒被收集在金属纤维过滤器上,把原状烟粒样品移入实验室反应器,用模拟柴油机排气进行燃烧试验。实验结果表明,当烟粒中含有Pd或Cu时,烟粒的燃点温度可降至430℃左右(普通柴油机烟粒的燃点温度约600℃);Pd的添加还可大大降低烟粒一次燃烧产物中CO的分率。文中还对金属(催化剂)/烟粒接触程度和添加剂溶液中可燃性部分对烟粒燃烧的影响作了讨论。     

COMPACT COUPLED LINEAR TAPERED LINE BANDPASS FILTER WITH TWO TRANSMISSION ZEROS

A new compact bandpass filter composed of two coupled linear tapered line resonators (LTLRs) is designed. The two resonators are arranged in different layers. The filter has two transmission zeros on both sides of the passband. It has small size and steep response below its passband. It is also shown that this filter has 0.6 dB low insertion loss at the centre frequency and 10.5% 3dB bandwidth. This work was supported by the Development Foundation of Shanghai Educational Committee (217608) and Shanghai Leading Academic Discipline Project (T0102).     

惯性导航系统水平阻尼网络的自适应控制

当海况变化较大时，惯性导航系统(INS)的误差振荡幅度较大．为了减小系统误差的振荡幅度，提出了一种新的设计思想，采用自适应控制方法，根据实际的海况变化情况，实时校正阻尼参数，使由舰船的机动性造成的系统误差最小．结果表明，与传统方法相比，水平误差角振荡幅度减小了约50％，速度误差振荡幅度减小了约30％．经度、纬度和航向误差振荡幅度也有明显改善；水平阻尼网络的自适应控制有效地改善了INS的动态性能．     

直流稳压电源波形演示器制作说明

直流稳压电源可以将交流电压变换为直流电压,并使之稳定,在我们现实生活中应用很广泛,在实验中我们利用的电学知识,设计制造了一种直流稳压电源。本文简要介绍了这种直流稳压电源波形演示器的设计目的和电路原理,重点阐述了它的制作流程、滤波和稳压原理以及性能测试输出波形。