旋风分离器不同排气管形状对性能影响研究

目前针对旋风分离器排气管的研究主要围绕排气圆管直径与内伸长度进行,而排气管内伸部分形状变化对分离器性能有着重要影响。在一个标准Stairmand型分离器基础上,建立了排气管圆管直径变化和圆管内伸部分进行“内缩型”及“内扩型”改变等3组共9个分离器模型,采用流体力学方法计算其分离效率和压降,讨论不同模型性能之间的关系：分离器分离效率会随着排气管圆管直径的减小而明显提高,但压降也随之大幅增加,提升分离效率和减小压降构成矛盾的优化目标;当排气管直径大于0.4D后,排气管内伸部分“内缩型”改变可以提高分离效率,而“内扩型”改变会小幅度降低分离效率却较大幅度减小了压降。这为不同优化目标（提高效率或降低压降）的旋风分离器排气管结构设计提供参考依据

An I/O Scheduling Algorithm for Solid State Disk Based on Request Size

对于同类型的I/O请求,基于闪存固态盘的请求响应时间与请求大小基本呈线性比例关系,并且固态盘的读写性能具有非对称性。针对该特性,提出一种基于请求大小的固态盘I/O调度(SIOS)算法,从I/O请求平均响应时间的角度提高固态盘设备的I/O性能。根据读写性能的非对称性,对读写请求进行分组并且优先处理读请求。在此基础上首先处理等待队列中的小请求,从而减少队列中请求的平均等待时间。采用SlC和MlC 2种类型的固态盘进行实验,在5种测试负载的驱动下与lInuX系统中的3种调度算法进行比较,对于SlC固态盘,SIOS平均响应时间分别减少18.4%、25.8%、14.9%、14.5%和13.1%,而对于MlC固态盘,平均响应时间分别减少16.9%、24.4%、13.1%、13.0%和13.7%,结果表明,SIOS能有效减少I/O请求的平均响应时间,提高固态盘存储系统的I/O性能。The response times are linear with the request sizes for flash-based Solid State Disk(SSD) with the same request type.Moreover, the read performance and write performance of flash-based SSD are asymmetric.Based on these characteristics, this paper proposes a Size-based I/O Scheduler(SIOS) for flash-based SSD to improve the I/O performance of SSD-based storage systems from the viewpoint of average response time.SIOS utilizes the asymmetric read and write performance characteristics of flash-based SSD and gives higher priority to the read requests.Moreover, by first processing the small requests in the I/O waiting queue, the average waiting times of the requests are reduced significantly.It implements SIOS in the Linux kernel and evaluates it with two kinds of SSD devices(SLC and MLC)driven by the five traces.Compared with the existing Linux disk I/O schedulers, evaluation results show that SIOS reduces average response times by 18.4%, 25.8%, 14.9%, 14.5% and 13.1% for SLC-based flash SSD, and reduces average response times by 16.9%, 24.4%, 13.1%, 13.0% and 13.7% for MLC-based flash SSD.Results show that compared with the state-of-the-arts, SIOS reduces the average response times significantly.Consequently, the I/O performance of the SSD-based storage systems is improved.国家自然科学基金青年科学基金资助项目“重复数据删除存储系统的数据重构性能和能效研究”(61100033

Diversity of bacterial community structure and its driving factors in three bays of Bohai Sea

[Background] Sustainable development of coastal ecosystem has become one of the most important concerns for people nowadays. Riverine output and anthropogenic interrupt have important impacts on the coastal environment. [Objective] In this study, we collected 12 samples from three transects including Bohai Bay, Liaodong Bay and Laizhou Bay to explore the microbial community and diversity in summer of 2015. [Methods] DNA was extracted from water samples by using DNA extraction kit. Samples were analyzed by Illumina HiSeq sequencing technology. We compared the differences among these three transects according to the analysis results. [Results] The diversity index and rarefaction curves showed significant differences among these three transects. The order of diversity value was Laizhou Bay>Bohai Bay>Liaodong Bay. The distribution of the dominant community was as follows: the proportion of Proteobacteria, Bacteroidetes, Cyanobacteria, Actinobacteria and Planctomycetes in the Bohai Bay was 39.8%, 25.7%, 22.4%, 5.85% and 4.38%, respectively. The dominant community proportion in Liaodong bay was Proteobacteria (37.8%), Bacteroidetes (25.7%), Cyanobacteria (17.8%), Actinobacteria (10.4%) and Planctomycetes (5.64%). While in Laizhou Bay there were only four dominant communities as follows: Proteobacteria (59.0%), Bacteroidetes (17.5%), Cyanobacteria (8.2%), Actinobacteria (7.88%). By using the principal component analysis (PCA) and Heatmap correlation analysis, we found that environmental factors were key roles in controlling the microbial diversity in the Bohai Sea. Among them, the concentration of nitrate was particularly significant according to the Mantel test analysis. [Conclusion] The microbial diversity in the three bays of Bohai Sea was very rich and multifarious. The population structure and species in the Laizhou Bay is the most complex and abundant among these three bays, and then it is Bohai Bay and Liaodong Bay. There was a significant correlation among microbial diversity, environmental factors and the spatial distribution. Above all, this study will provide a theoretical basis for further protection and ecological development of Bohai Sea

与南海西边界流有关的区域海洋学进展

从动力学角度,回顾了与南海西部主流系及其涡旋研究有关的南海物理海洋学的进展.主要内容涉及南海西边界流漂流浮标观测、西边界流源区涡旋遥感观测、西边界流源区跨陆架交换、涡流相互作用、西边界流年际变化、西边界流区海气相互作用、南海贯穿流等方面的进展.西边界流是一个强流系,其与季节和年际变化相关的结构特征、变率及跟某些动力过程的关联有待研究.在西边界流变率、涡旋环流相互作用、海气过程以及南海贯穿流取得了以下成果:(1)利用漂流浮标观测样本对南海西边界环流进行分析,指出南海西边界表层环流在到达越南中部沿岸后伴随着流幅变窄的同时流速加强;探讨了南海北部环流变化机理,定量诊断南海西边界流北支冬季逆风流产生的动力机制;利用航次数据对18°n断面的经向地转流进行诊断,表明南海西边界流的经向输送年际变化明显;(2)结合航次观测数据,对2003/2004年冬季南海北部2个反气旋涡旋和2007年夏季18°n附近的3个反气旋涡旋进行研究,指出冬季2个涡旋产生后以罗斯贝(rOSSby)波速度(约0.1M/S)沿北部陆坡向西南方向传播,并初步揭示了南海西边界环流与夏季3个涡旋的相互作用;南海北部陆架区涡旋西南向传播最大(最大为0.09M/S),而越南以东海域涡动能(EkE)最大,这都说明涡旋活动与南海西边界流存在强的相互作用;(3)发现南海西边界流附近海表面温度(SST)强的季节内振荡特征,进一步研究表明此区域冬季SST季节内变化会使潜热季节内信号减弱20%;(4)探讨了南海贯穿流的长期变化特征以及与整个太平洋环流系统的相互关联.国家自然科学基金重点项目(40830851); 国家重点基础研究发展计划(2011CB403504); 中国科学院近海海洋观测研究网络——西沙南沙海洋观测研究站建设项目(KZCX2-EW-Y040)资

GC-RAIS: Garbage Collection Aware and Redundant Array of Independent SSDs

垃圾回收操作会显著影响固态盘的性能,进而导致固态盘阵列的性能波动.为此,提出一种基于垃圾回收感知的磁盘阵列(gC-rAIS),充分利用固态盘的高随机读特性和固态盘阵列中的热备份盘,以减轻垃圾回收操作对固态盘阵列性能波动的负面影响.当固态盘阵列中某个固态盘正在处理垃圾回收操作时,对于到达该固态盘的读请求采用重构方式处理,即读取同一条带上其他固态盘上的数据重构得到,而对于到达该固态盘的写请求则将写数据临时存放在热备盘中,并更新相应的校验信息.当垃圾回收过程结束后,将被重定向的写数据写回到正确的固态盘中.仿真实验结果表明相对局部垃圾回收lgC策略和全局垃圾回收ggC策略,gC-rAIS分别减少用户I/O请求的平均响应时间达55%和25%.SSDs are popular in large-scale storage systems to accelerate the system performance because a single SSD cannot satisfy the performance, capacity and reliability requirements of data-intensive computing applications.Thus applying RAID algorithms to SSDs is necessary and promising to build high performance, high capacity and highly reliable SSD-based storage systems.However, garbage collection operations in SSDs have a significant impact on the SSD performance, thus leading to the performance variability in redundant array of independent SSDs (RAIS).To address this problem, GC-RAIS exploits the high random-read performance characteristics of SSDs and the hot-spare SSD in RAIS to alleviate the negative impact of GC operations on the RAIS performance.When an SSD is in the GC state, the incoming read requests to this SSD are serviced by reconstructing the read data from the other SSDs in the same stripe (read reconstruction), while the incoming write data is temporally stored on the hot-spare SSD and the corresponding parity is concurrently updated (write redirection).After the GC process completes, the redirected write data is reclaimed to its correct SSD.The original DiskSim and the MSR SSD simulator are extended to implement the proposed GC-RAIS and the GC-RAIS performance is evaluated with the HPC-like and enterprise realistic workloads.The simulation results show that GC-RAIS significantly outperforms the local garbage collection (LGC) and the global garbage collection (GGC) by 55% and 25% on average, respectively.Moreover, GC-RAIS reduces the performance variability for a wide variety of HPC-like and enterprise realistic workloads.国家自然科学基金项目(61100033); 中央高校基本科研业务费专项基金项目(2010121066); 国家重大科学仪器设备开发项目(2011YQ03012417

基于不同介质材料的AOTF特性研究综述

基于不同介质材料的AOTF（声光可调谐滤波器）具有不同的性质及应用场合。目前应用于紫外、可见光和红外波段的AOTF主要以α-SiO2、TeO2和TAS（Tl3AsSe3）为介质。为了得到性能更优的AOTF,人们一直在探寻新型双折射晶体材料来代替α-SiO2和TAS。文章汇总并讨论了近年来人们针对基于TeO2、KDP（KH2PO4）、MgF2和Hg2Cl2等材料的AOTF的研究工作,结果显示,上述材料具有更多的优点,但同时也有一些不足之处,因此人们需要根据不同的应用场合选择不同的材料

Bar counting method based on machine vision

本发明提供了一种基于机器视觉的棒材计数方法，包括采集棒材端面图像，图像预处理，计算棒材的相对位移，连通域分析，棒材匹配计数，确定分钢线位置以及判断初分钢结果是否正确等。图像预处理包括平滑、二值化及形态学操作；连通域分析首先将粘连棒材分割成单根棒材，然后再次用连通域分析单根棒材的信息。本发明方法基于机器视觉技术，实现了棒材的自动计数及分钢结果判断，有效解决了棒材的重叠与交叉问题，该方法速度快，准确率高，对生产线的改动小，易于维护，大大减少企业在生产过程中的人力成本

基于方位特征集的飞机侧开式登机舱门开启机构变模式运动分析

登机舱门作为大型客机的一个重要部件，其运动状态和运动模式分析对于舱门功能和运动链设计至关重要。从机器人机构拓扑综合视角，首次提出将某型侧开式登机舱门开启运动机构抽象为2条SS支路与1条◇(R//R//R//R)⊥R//R支路构成的并联机构，进行了舱门及其开启机构运动关联性研究。基于并联机构方位特征集（POC）理论，分析了侧开式登机舱门开启机构拓扑尺度约束类型特征，揭示了舱门机构提升和旋转运动过程具有1个自由度且选取不同独立元素的两种运动模式，进一步发现舱门运动模式切换的几何约束条件为：铰链臂机构转动副间距与平行杆机构杆长在水平面投影尺寸相等。结合挡块限位的舱门驱动保证几何约束条件恒定，提升了舱门模式切换的确定性及开启过程的稳定性。基于方位特征集进行的侧开式登机舱门开启过程研究为飞机舱门设计提供了新思路

基于同伦连续法的飞机舱门提升机构轨迹综合

飞机舱门是进出机舱的通道，其机身导向槽中心线与提升机构末端导向轮运动轨迹重合，保证了舱门开启/锁止可靠。以有序单开链方法建立提升机构2个单开链单元轨迹综合运动学方程组；方程组变量齐次化分组，其Bezout数仅为320，减少同伦跟踪路径；分别进行初始方程组构造和同伦方程组求解，求得了6组杆长非负实数构形解，绘制了单开链单元组合的对应构形。以机构运动空间和提升机构力传递效率进行构形筛选，得到了可实现飞机舱门按期望轨迹运动的舱门提升机构

京津冀风沙源区沙化土地治理关键技术研究与示范

京津冀风沙源区是我国北方生态屏障的重要组成部分。面向我国北方风沙区沙化土地综合治理、典型脆弱生态修复与保护等重大科技需求,京津冀风沙源区沙化土地治理关键技术研究与示范项目将综合运用长期定位观测、控制实验、多源遥感数据融合、技术示范等方法,重点研究京津冀风沙源区土地沙化形成机制与生态修复机理,研发一批沙化土地治理与产业化关键技术,并在各治理区开展试验示范,集成京津冀风沙源区沙化土地治理与产业化技术体系,构建沙化土地综合整治空间决策支持系统,为京津风沙源治理工程建设、保障京津冀地区生态安全及满足2022年北京冬奥会生态需求提供科技支撑