外腔半导体激光器设计与高次谐波稳频

研究了利特罗(Littrow)结构外腔半导体激光器的结构参量对激光连续可调范围的影响。给出了反射镜转轴等处的机械加工误差对激光波长连续可调范围所造成的影响的数值计算结果。介绍了半导体激光器外腔结构设计的具体细节要点。利用该设计制作的外腔只需要配合商用半导体激光管便可以得到优质的780nm激光输出,经测量其线宽小于1MHz,连续可调谐范围大于3GHz。利用腔外Rb饱和吸收谱的三、五次谐波稳频方法对半导体激光器进行了稳频。其中提出了优化激光频率短期稳定度的方法,并对调制深度的选择给出了详细的理论解释。根据该优化方法设计出稳频系统对半导体激光器进行稳频,得到了稳定度达到10-12量级的半导体激光输出。     

基于眼、嘴、耳廓之间结构关系的人耳识别

人耳识别作为一种新的生物特征识别技术，正在逐步成为该领域中的热点。本文针对眼、嘴、外耳轮廓的结构关系．提出一种多模态生物特征识别方法，该方法提取的特征向量包括八项特征，比如外耳轮廓宽度与两瞳孔之间水平距离之比、外耳轮廓高度与瞳孔和嘴之间的垂直距离之比、脸的宽度与两瞳孔之间水平距离之比，然后通过模式识别对样本进行分类。由于提取的特征均以相对量为主，所以该算法具有“缩放性”，同时对噪声具有较强鲁棒性．识别效果较好。     

电场下[001]cub切型弛豫铁电单晶PMN-32PT电畴的极化反转

为研究弛豫铁电单晶PMN-32PT电畴在电场下的极化反转,利用偏光显微镜研究了电场下[001]_(cub)切型PMN-32PT单晶电畴组态的变化,建立了极化反转模型.在[001]_(cub)单晶切片中,当电场强度达到4kV/cm时,电畴开始极化反转,出现平行于电场方向的畴壁,畴壁沿垂直自身的方向运动,畴壁的运动实际是畴的横向扩张;当电场强度增至6kV/cm时,畴壁消失,又出现垂直于电场方向的新畴壁;而电场强度进一步增至10kV/cm时,新畴壁也消失,且电畴消光,这表明多畴已单畴化.     

A survey on resource allocation in high performance distributed computing systems

An efficient resource allocation is a fundamental requirement in high performance computing (HPC) systems. Many projects are dedicated to large-scale distributed computing systems that have designed and developed resource allocation mechanisms with a variety of architectures and services. In our study, through analysis, a comprehensive survey for describing resource allocation in various HPCs is reported. The aim of the work is to aggregate under a joint framework, the existing solutions for HPC to provide a thorough analysis and characteristics of the resource management and allocation strategies. Resource allocation mechanisms and strategies play a vital role towards the performance improvement of all the HPCs classifications. Therefore, a comprehensive discussion of widely used resource allocation strategies deployed in HPC environment is required, which is one of the motivations of this survey. Moreover, we have classified the HPC systems into three broad categories, namely: (a) cluster, (b) grid, and (c) cloud systems and define the characteristics of each class by extracting sets of common attributes. All of the aforementioned systems are cataloged into pure software and hybrid/hardware solutions. The system classification is used to identify approaches followed by the implementation of existing resource allocation strategies that are widely presented in the literature.     

社区服务系统的设计

采用Visual Studio.NET技术及SQL Server数据库开发工具,使用面向对象的方法设计并开发了社区服务系统.系统实现了发布新闻公告、提供信息资讯、查看收费情况、论坛交流、网站维护等主要功能,为社区居民之间以及居民与物业公司之间提供了一个信息化的平台.     

细菌觅食算法求解二次分配问题

为有效解决二次分配问题,提出了一种基于群体搜索的群智能优化算法—细菌觅食算法.算法模拟了细菌觅食全过程,并将细菌个体信息与探索细菌群体信息进行结合,采用了群体搜索策略进行局部寻优.该策略有效的避免了算法陷入局部最优,而算法中采用的自适应搜索步长,进一步提高了优化的收敛速度.实验结果表明,用细菌觅食算法解决二次分配问题,并将仿真结果与其他算法进行比较,表明了该算法的搜索质量优于其他算法.     

Peat fires detected by the BIRD satellite

Tropical peat swamp forests store huge amounts of carbon, which is released to the atmosphere as carbon dioxide during fires. Recurrent peat swamp forest fires are local catastrophic events that can have a serious impact on the global carbon balance. Urgent tasks in this regard are the provision of information on the fire locations and magnitude of the carbon emissions. The experimental Bi-spectral InfraRed Detection (BIRD) satellite enables early detection of peat swamp forest fires and retrieval of their quantitative characteristics, such as the effective fire temperature, area and radiative energy release. The combination of ground truth measurements and data obtained by BIRD can improve the accuracy of estimates of carbon emissions into the atmosphere and related trace gas composition.     

Adaptive workload driven dynamic power management for high performance computing clusters

With the scale expansion of high performance computer systems, efficient power management has developed into an important issue. To strive to balance power consumption and performance, this paper proposes an adaptive workload-driven dynamic power management policy for homogeneous clusters, which dynamically adjusts the power mode of computing nodes according to workload variation. The proposed policy combines the pre-wakeup method and the feedback mechanism to reduce performance degradation due to the wakeup delay. The experimental results demonstrate that, as compared with two existing timeout policies, adaptive workload-driven dynamic power management effectively reduced the performance loss with a slight increase in power consumption.     

超高频射频识别湿度传感器的分析与测试

读写器和标签组成的射频识别系统(RFID)可以用于湿度测量.本文通过理论分析,数值仿真以及实验测试给出了可用于湿度传感器的EPC Gen2电子标签的特性.分析结果表明,当湿度变化时,标签天线和标签之间的阻抗匹配系数单调变化的标签才可用做湿度传感器.在空气中,标签天线和标签芯片完全匹配的标签可以用于湿度测量.本文还在实验...     

移动自组织网络基于极端预测的节能路由算法

在移动自组织网络中,减少移动节点电池能量消耗,延长网络生存时间,是路由协议性能优劣的一个重要指标.针对这一问题,提出了一种基于极端预测的路由算法,根据门限值划分节点稳定域,计算链路有效性,以最大最小路径有效性原则选路.同时,节点根据下一跳节点的位置自动调整发射功率,以达到节能的目的.仿真结果表明该算法与DSR相比能有效...