Dynamic gain and output power control in a gain-flattenederbium-doped fiber amplifier

We demonstrate an erbium-doped fiber amplifier (EDFA) that has a flat-gain spectrum over an 18-nm band and a constant per-channel output power regardless of the input powers and the number of channels. The gain flatness and the constant output are obtained by changing the laser diode pump power and the attenuation of the voltage-controlled attenuator (VCA) dynamically. The response times of pump control circuit and attenuator control circuit are 650 ns and 9 ms, respectively. The power excursion of surviving channel in an EDFA with fast control circuit is ~1% of that without fast control circuit when channels are added or dropped     

柳毛石墨矿生产工艺的改造

介绍了柳毛石墨矿选厂的矿石性质、石墨分选工艺特点等;针对其存在的问题,提出采用振磨机代替球磨等改造措施,可生产出高品质石墨精矿,并可降低能耗,提高经济效益。     

气凝胶建筑玻璃透光隔热性能及影响因素

新型气凝胶玻璃具有良好的透光隔热性能,作为高性能建筑玻璃能有效降低建筑能耗。通过气凝胶颗粒粒径和填充厚度设计,制成8种不同结构的气凝胶填充玻璃;实验研究了气凝胶颗粒粒径与填充厚度对气凝胶玻璃透光和隔热性能的影响。结果表明:当气凝胶粒径从0.41mm增大到0.93mm时,玻璃透光率明显增大,而当气凝胶粒径继续增大时透光率变化不大;当气凝胶粒径从0.41mm增大到2.7mm时,气凝胶玻璃传热系数增大约15%;相对于普通玻璃,相同尺寸的普通玻璃传热系数最多可降低51.43%。采用玻璃隔热实验测试研究了气凝胶玻璃与普通中空玻璃的隔热温差,结果表明,气凝胶玻璃较普通玻璃隔热效果提高5.4~10.2℃。     

工业机器人开放式控制系统研究综述

控制系统作为工业机器人的重要组成部分在一定程度上制约着机器人技术的发展。首先对开放式机器人控制系统的研究进行概括与总结,重点对工业机器人控制系统的结构特点、系统开放性的软硬件实现方法进行阐述,接着总结开放式控制系统在多机器人协同控制应用现状,并且对控制系统未来的发展方向进行了展望。     

Current performance and future trends in health care sciences and services research

Health care sciences and services research (HCSSR) has come to the fore in recent years and related research literature increased rapidly over the last few decades. The main purpose of this study is to describe the global progress and to determine the current trends on HCSSR by using a scientometrics approach to survey related literature in the Web of Science database from 1900 to 2012. The document types, languages, publication patterns, subject categories, journals, geographic and institutional distributions, top cited articles, and the distribution of keywords were thoroughly examined. The results show that HCSSR has increased rapidly over the past 20 years, most notably in the last decade. In total, there are currently 128,728 research articles in 156 journals listed in 39 WoS subject categories. The top 20 most productive countries, and institutions were analyzed in detail, and 11 frequently cited papers and research foci were identified based on citation analysis. HCSSR spans many disciplines and focuses mainly on public, environmental & occupational health and education educational research. Medical Care, Academic Medicine, Health Affairs and Journal of School Health are the core journals with both high quantity and quality. High-income countries make up the leading nations, especially G7 countries. Meanwhile, “emerging economies” are also increasingly engaging this field. American and Canadian institutions have made greater advances in productions, citations, and cooperation, with stronger and better development prospects overall. The hot topics include internet use and decision making in health care, palliative care and end of life research, health status and quality of life, quality of healthcare and patient’s satisfaction, medical education, and health communication. Also, most researchers tend to study health care sciences based on the topics of quality-of-life assessment, and their interest in quality-of-life measures has increased. Increasing attention has been paid to the developing countries, especially “emerging economies” like China. Although health research has made much progress, many questions still remain unanswered and there are few assessments of how well research systems carry out their essential functions. Hence, there is currently an urgent need for timely establishment of an effective health research system.     

基于SSD的多因素融合的驾驶疲劳检测研究

为了降低因疲劳驾驶而导致的事故发生率,提出一种利用卷积神经网络与人脸特征点、疲劳判定指标相融合的方法,共同构建疲劳驾驶检测模型。首先利用SSD（Single Shot MultiBox Detector）网络定位驾驶员的眼睛与嘴巴区域,VGG16 网络学习这两个区域所包含的疲劳特征;同时再结合人脸68特征点、眼睛纵横比（Eye Aspect Ratio, EAR）和嘴巴纵横比（Mouth Aspect Ratio, MAR）共同判定驾驶疲劳状态。最后,在相同测试集下分别计算SSD算法和Faster-RCNN算法的平均精度均值mAP;在YawDD数据集上应用此模型;并通过模拟驾车环境来验证此模型的可行性。实验结果表明,SSD算法要优于Faster-RCNN算法,并且此模型在YawDD数据集上的检测准确率约达97.2%,摄像头也能对驾驶员的状态进行实时检测。此模型对疲劳状态的检测十分有效,可在一定程度上降低因疲劳驾驶而导致的事故发生率。     

塔里木盆地顺北地区中-下奥陶统“断控”缝洞系统划分与形成机制

碳酸盐岩地层普遍发育各类成因机制的非均质性缝洞储层,其孔隙系统的形成演化受岩石的地质演化控制。一般情况下,这类非均质性缝洞储层的形成与地层流体系统中各种不饱和性流体的热化学作用方式和所能带走的物质体积总和有关。但是,塔里木盆地顺北地区发现的“断控”缝洞储层未经历不饱和性流体的溶蚀改造作用,其空间展布明显受到断裂带边界约束,勘探证实可以形成商业价值储层。因此,断裂活动能否发生大规模的物质体积调整,形成完整的缝洞储集系统,需要引起重视。通过应用三维地震、钻井异常工况、测井、元素录井、压恢试井、干扰试井和生产动态资料等,综合表征“断控”储层特征,反演“断控”缝洞单元和储集系统。针对走滑断裂活动过程中的岩石物理特性、构造增容机理和流体改造机制,开展了脆性岩层应变方式、断层封闭性控制因素、水-岩作用方式等研究,提出断裂带内部受岩体错动、破碎及力学-热化学作用而发生的物质体积调整是顺北地区“断控”缝洞储层形成的主导因素,其孔隙系统的形成、演化与断裂活动关系密切。当“断控”缝洞系统形成、演化过程中无法忽视流体影响时,可依据流体性质和作用方式等,细分出“岩溶型”和“热溶型”亚类,作为“断控”储层概念的理论衍生。     

Effect of Signature Sequence on the Performance of an Asynchronous Multiple-Chip-Rate DS/CDMA System

The effects of signature sequence on the performance of an asynchronousmultiple-chip-rate (MCR)-DS/CDMA system are considered.The equations for the multiple access interference (MAI)and the variance of the MAI are developed.The bit error rate is derived by using the Gaussianapproximation.The deterministic signature sequences such as maximal-lengthsequences and Gold sequences are compared with random signature sequencesin terms of the variance of the MAI and bit error rate.We find that the performance of signature sequences in an asynchronousMCR-DS/CDMA system depends not onlyon the crosscorrelation properties of sequences but also on the carrierfrequencyseparation between the interfering and desired users.