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/℃.     

Direct3D在航空火控空战模拟系统开发中的应用

研究了 Direct3D技术在航空火控空战模拟系统开发中的应用 ,介绍了软件开发方法 ,最终得到了成果软件。     

Thermoelectric Generation Using Water Lenses

A solar light concentrator composed of water and plastic transparent film has been designed. This flexible lens design can trace the solar movement through control of the tensile stress and amount of water, and concentrate the solar energy onto the thermoelectric (TE) module surface. An experimental water lens was constructed, and the concentrated intensity was monitored by a photodiode as a function of x–z position; For example, when 3.0 kg water was filled and tension of 69.0 N/m was applied to the transparent vinyl sheet, the concentration ratio was evaluated as the maximum of 28.0 at a depth of 657 mm from the water lens bottom surface. TE generation was tested to show the validity of the water lens. The surface condition of the receiver was found to be critical.     

网络环境下智能化学习模式构建与实践研究

随着计算机技术和网络技术的飞速发展,以及各种移动设备的应用与普及,网络环境下的学习方式已经成为新时期现代化教学方式发展的新方式.但目前网络环境下的学习方式还存在如上课形式单一、学习资源不足、学生自主学习能力弱、课堂互动较少、各种教学活动不易于控制等问题,那么就急需构建网络环境下新的学习方式.将智能化融入教学过程中不仅能...     

Facilitation of Gene Transfection and Cell Adhesion by Gelatin‐Functionalized PCL Film Surfaces

Efficient local gene transfection on a tissue scaffold is of crucial importance in facilitating tissue repair and regeneration. In this work, the gelatin‐functionalized polycaprolactone (PCL) film surfaces are prepared via surface‐initiated atom transfer radical polymerization of glycidyl methacrylate. The resultant covalent attachment of gelatin could enhance the cell‐adhesion and local gene transfection properties. The gelatin‐functionalized PCL film surfaces exhibit excellent cell‐adhesion ability to both adherent and suspension cells. The attached adherent cells demonstrate the characteristic elongated morphologies with good spreading capability, while the attached suspension cells can maintain the original status of the round morphologies without spreading. More importantly, the gelatin coupled on the PCL surface could be used to absorb the cationic vector/plasmid deoxyribonucleic acid (pDNA) complexes via electrostatic interaction. The local gene transfection property on the immobilized cells is dependent on both the density of the immobilized cells and the loading types of pDNA complexes. The transfection efficiency of different assemble methods of pDNA complex was compared. With the pre‐ and post‐loading sandwich‐like gene transfection, the gelatin‐functionalized PCL film surface can substantially enhance the transfection properties to different cell lines. The present study is very useful to spatially control local gene delivery within PCL‐based tissue scaffolds.