差压变送器在监测系统中的应用及故障处理

简单介绍了差压变送器的工作原理,设计出一套采集系统,利用北京鼎升力创R8000系列模块和差压传感器的配合来完成对数据的采集。并对R8000系列模块、差压变送器、引压管、变频干扰等在使用过程中的常见故障进行分析,提出解决方法。     

ISP器件在高速通信系统中的应用

ISP器件具有集成度高、功能强、速度快、设计灵活和在系统逻辑重构等优点。为了改善数字通信系统发射和接收数据的同步性能，保证系统工作稳定、可靠，用ISP器件实现数字相关器。本文介绍了数字相关器的工作原理，电路设计方案和实现过程。针对通信系统中对速度的要求，在电路设计中采用了流水线技术，用Max＋PlusⅡ软件设计了十六位高速数字相关器。给出了十六位高速数字相关器顶层逻辑电路图及仿真波形图，由波形图可以看出，系统工作速度等于时钟频率。系统仿真正确后，用ISP器件实现了高速数字相关器。     

Biomimetic Hygroscopic Fibrous Membrane with Hierarchically Porous Structure for Rapid Atmospheric Water Harvesting

Sorption-based atmospheric water generation (SAWG) is a promising strategy to alleviate the drinkable water scarcity of arid regions. However, the high-water production efficiency remains challenging due to the sluggish sorption/desorption kinetics. Herein, a composite sorbent@biomimetic fibrous membrane (PPy-COF@Trilayer-LiCl) is reported by mimicking nature's Murray networks, which exhibits outstanding water uptake performance of 0.77–2.56 g g⁻¹ at a wide range of relative humidity of 30%–80% within 50 min and fast water release capacity of over 95% adsorbed water that can be released within 10 min under one sun irradiation. The superior sorption–desorption kinetics of PPy-COF@Trilayer-LiCl are enabled by the novel hierarchically porous structure, which is also the critical factor to lead a directional rapid water transport and vapor diffusion. Moreover, as a proof-of-concept demonstration, a wearable SAWG device is established, which can operate 10 sorption–desorption cycles per day in the outdoor condition and produce a high yield of clean water reaching up to 3.91 kg m⁻² day⁻¹. This study demonstrates a novel strategy for developing advanced solar-driven SAWG materials with efficient water sorption–desorption properties.     

基于CPLD设计实现单横单纵激光器种子注入纵模锁定

基于自滤波非稳腔、种子激光注入及CPLD控制的干涉法纵模锁定技术,研制出一套单横单纵激光器系统；对激光器的工作原理及纵模锁定电路设计进行了说明。该设计具有输出光束质量好,工作稳定,抗干扰性强的特点。该激光器经历了在强干扰环境中长时间的“烤机”实验,单纵模锁定概率达100%。     

A blind SNR estimator for digital bandpass signals

A subspace-based blind Signal-to-Noise Ratio （SNR） estimation algorithm for digital bandpass signals in Additive White Gaussian Noise （AWGN） channel is discussed. The lower bounds of the mean and variance of the estimation are derived, and simulations are performed for the commonly used digital bandpass signals, such as MPSK （M=2, 4, 8）, MFSK （M=2, 4） and MQAM （M=16, 64, 128, 256） signals. Theoretical analyses and simulation results indicate that the proposed algorithm is effective even when the SNR is below 0dB. Furthermore, the algorithm can provide a blind estimator in that it needs neither the parameters of the received signals, such as the carrier frequency, symbol rate and modulation scheme, nor the synchronization of the system.     

五四时期《科学》广告的科学传播功能

五四时期,以《科学》为代表的科技期刊有力地推动了科学知识的传播与科学意识的启蒙。作为科技传播的形武之一,《科学》杂志的广告在科技传播的过程中也发挥了积极的作用。通过统计、分析五四时期《科学》的广告,提出五四时期《科学》杂志的广告通过搭建“传受平台”而间接发挥其建构功能的观点;同时探讨了《科学》广告传播科学知识与培养科学意识的两大功能。     

大尺寸TFT-LCD电视的彩色和图像增强

最近几年,薄膜晶体管液晶显示器(TFT-LCD)技术取得了快速而显著的进步,其性能超过了PDP、CRT以及投影显示。毫无疑问,TFT-LCD已经成为高清电视应用的最佳实现方案。本文将介绍进一步增强大尺寸LCD电视的彩色和图像性能的技术。     

Digital Cross-Correlation Detection of Multi-Laser Beams Measuring System for Wind Field Detection

A cross-correlation detection method to process backscatter signals of multi-laser beams measuring(MLBM) is presented,which can be firstly filtered by the digital filter composed of average median filter and finite impulse response(FIR) digital filter.The processing of backscatter signals using single-pulse and three-pulse cross-correlation detection methods is depicted in detail.From calculation results,the multi-pulse cross-correlation detection could effectively improve signal-to-noise ratio(SNR).Finally,both wind velocity and direction are determined by the peak-delay method based on the correlation function which shows high measuring precision and high SNR of the MLBM system with the assistance of the digital cross-correlation detection.     

200～1 100 nm光响应测试系统的研制

设计并制作了２００～１１００ｎｍ的光响应测试系统,该系统工作稳定可靠,并可消除光源拌动和突发性光源对测试的影响。     

Luminescent high temperature sensor based on the CdSe/ZnS quantum dot thin film

A high temperature sensor based on the multi-parameter temperature dependent characteristic of photoluminescence （PL） of quantum dot （QD） thin film is demonstrated by depositing the CdSe/ZnS core/shell QDs on the SiO2 glass substrates. The variations of the intensity, the peak wavelength and the full width at half maximum （FWHM） of PL spectra with temperature are studied experimentally and theoretically. The results indicate that the peak wavelength of the PL spectra changes linearly with temperature, while the PL intensity and FWHM vary exponentially for the tem- perature range from 30 ℃ to 180 ℃. Using the obtained temperature dependent optical parameters, the resolution of the designed sensor can reach 0.1 nm/℃.