数字全息光电再现中像的大小调整方法的研究

从数字全息光电再现的基本原理出发,分析了数字全息光电再现影像大小和再现距离的关系,推导了计算公式.建立了数字全息光电再现实验系统,用数字微反射镜器件（Digital Micro-mirror Device,DMD）的空间光调制器（Spatial Light Modulator,SLM）对光学记录的头像数字全息图进行了光电再现,并给出了实验结果.     

基于四叉树的光学小波滤波器轴心定位的研究

精度问题制约了光学小波变换的广泛应用。若要扩展其应用领域,必须提高变换精度。在二维光学小波变换4f系统中,小波滤波器轴心的精确定位至关重要。提出了一种基于四叉树搜索方法的光学小波滤波器轴心定位方法。所用的加载滤波器载体为空间光调制器(SLM),定位精度可达到SLM的一个像素大小。为加快搜索速度,提出了一种基于四灰度级并行处理的改进方法。     

一种降低OFDM系统峰均比的循环反馈SLM方法

在正交频分复用（orthogonal frequency division multiplexing,OFDM）系统中,若各支路在同一相位上叠加会带来幅值的叠加从而产生大的峰均比（peak to average power ratio, PAPR）。选择性映射方法是一种有效降低正交频分复用系统峰均比的方法,对传统的选择性映射方法做了改进,提出了一种新的循环反馈选择性映射算法。在该算法中, 采用了若干ZC（Zandoff-Chu）序列作为初始的相位旋转矢量,对于传统选择性映射方法中的每个子块不再固定其相位矢量,而是根据峰均比比较结果的反馈做出相应的相位矢量调整。通过在AWGN(additive white Gaussian noise)信道环境进行仿真,进一步分析加入循环反馈选择性映射算法的OFDM系统和传统OFDM系统。仿真结果表明,提出的加入循环反馈选择性映射算法可有效地降低峰均比并改善接收端的比特误码率（bit error rate,BER）性能。     

体全息存储中SLM和CCD的性能对页内噪声的影响

体全息存储系统中通常采用SLM和CCD作为输入输出器件。SLM和CCD的性能包括填充因子、对比度和像素形状 ,这些性能会对像面页内像素间干涉程度产生很大的影响 ,进而影响页内噪声的大小。针对这一问题 ,首先进行了理论分析 ,然后通过计算机模拟了实际系统     

Continuous flow liquid membrane extraction: a novel automatic trace-enrichment technique based on continuous flow liquid-liquid extraction combined with supported liquid membrane

Combining the continuous flow liquid-liquid extraction (CFLLE) and supported liquid membrane (SLM) extraction, a novel aqueous-aqueous extraction technique that we termed continuous flow liquid membrane extraction (CFLME) is developed for trace-enrichment. The analyte was firstly extracted into the organic phase in the CFLLE step, then transported onto the organic liquid membrane that formed on the surface of the micro porous membrane of the SLM equipment. Finally, it passed through the liquid membrane and was trapped by the acceptor. Aspects related to CFLME were studied by using dichloromethane as liquid membrane, and sulfonylurea herbicides as model compounds. An enrichment factor of over 1000 was obtained when 10 μg l⁻¹ of MSM was enriched for 120 min by this technique. The drawbacks of only a few organic solvents can be selected as liquid membrane with a limited lifetime in SLM operation was overcome. In this CFLME method, almost all solvents that used in the conventional liquid-liquid extraction (LLE) can be adopted and the lifetime of liquid membrane is no longer a problem.     

Nuclear waste treatment by means of supported liquid membranes containing calixcrown compounds

Permeability variation with repeated caesium transport experiments has been chosen to measure the leaching of the supported liquid membrane by the contacting aqueous solutions. This allowed us to characterize the SLM stability. Whereas classical crown ethers such as the widely used 21C7 derivatives were revealed to be poorly efficient and poorly stable in SLMs, crown-6-calix[4]arene compounds in the so-called1,3-alternate configuration led to very stable (over 50 days), highly selective (concentration factor>100) and efficient (decontamination factor=20) SLMs, for the removal of caesium from high salinity and acidity media. These results were achieved by using proper organic diluents and introducing hydrophobic substituents in the frame of the calixarenes.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.     

基于STBC MIMO-OFDM系统特性的并行选择映射算法

正交频分复用(OFDM)技术是第四代移动通信系统的核心技术之一,但是高峰均功率比(PAPR)问题的存在一直是该技术实用化的主要障碍.针对该问题,证明了基于空时分组码的MIMO-OFDM系统中,共轭信号具有相同的峰均功率比特性,提出了基于相同峰均比特性的并行选择映射算法.所提算法不仅保持了已有并行选择映射算法的峰均比降低性能,同时有效地减少了算法复杂度,降低了边带信息的传输量,提高了系统的频带利用率.仿真实验结果证明了所提算法的有效性.     

Fabrication and characterization of selective laser melting printed Ti–6Al–4V alloys subjected to heat treatment for customized implants design

Selective laser melting(SLM) is a promising technique capable of rapidly fabricating customized implants having desired macro- and micro-structures by using computer-aided design models. However, the SLM-based products often have non-equilibrium microstructures and partial surface defects because of the steep thermal gradients and high solidification rates that occur during the laser melting. To meet clinical requirements, a heat treatment was used to tailor the physiochemical properties, homogenize the metallic microstructures, and eliminate surface defects, expecting to improve the cytocompatibility in vitro. Compared with the as-printed Ti–6Al–4V substrate, the heat-treated substrate had a more hydrophilic, rougher and more homogeneous surface,which should promote the early cell attachment, proliferation and osseointegration. More importantly, a crystalline rutile TiO_2 layer formed during the heat treatment, which should greatly promote the biocompatibility and corrosion resistance of the implant. Compared to the untreated surfaces, the adhesion and proliferation of human bone mesenchymal stem cells(hBMSCs) on heat-treated substrates were significantly enhanced, implying an excellent cytocompatibility after annealing. Therefore, these findings provide an alternative to biofunctionalized SLM-based Ti–6Al–4V implants with optimized physiochemical properties and biocompatibility for orthopedic and dental applications.     

Direct coupling of supported liquid membranes to capillary electrophoresis for analysis of complex samples: A tutorial

This tutorial provides an overview of direct coupling of extraction techniques based on supported liquid membranes (SLMs) to capillary electrophoresis (CE) for treatment and subsequent analysis of complex samples. Pros and cons of using each of the described instrumental arrangement are addressed and where relevant, comments with personal experience of the authors are presented. Solid porous membrane based extraction techniques coupled directly to CE are also presented in this tutorial and a comprehensive discussion is included on their instrumental set-ups and their possible adaptation for use with SLMs.     

基于全息成像技术构建任意的二维光晶格阵列

利用Gerchberg-Saxton算法生成任意的二维光晶格阵列的全息图,并且将全息图加载到液晶型空间光调制器上,然后将850 nm的激光照射到空间光调制器的液晶屏上,利用透镜的傅里叶变换特性,成功地显示或构建任意形状的二维光晶格阵列。将该系统应用到87Rb的冷原子实验中,成功俘获冷原子,这为接下来的单原子多量子位的量子模拟实验奠定了基础。