一种应用于DaaS的物化视图候选集生成算法

针对DaaS数据中心建设中物化视图选择对候选视图集的新要求和传统MVPP方法的不足,提出一种新的候选视图集生成算法。该算法利用多操作变换规则进行查询优化,然后利用算法1和2进行关系融合。实验证明,该算法能够提高查询效率,压缩候选视图集,具有较高的可扩展性,符合应用需求。     

端视ICP-AES法直接测定食品添加剂DL-酒石酸中有害元素

通过同时提高RF 发射功率及雾化气流量,使端视电感耦合等离子体原子发射光谱(ICP-AES)法可以直接用于测定食品添加剂DL- 酒石酸中有害元素铅和砷。确定了ICP-AES 测定条件。铅和砷的检出限分别为0.003mg/L和0.005mg/L,定量限分别为0.25mg/kg 和0.41mg/kg,回收率为96.2%～105.6%,相对标准偏差为1.82%～2.42%。本法完全满足食品添加剂DL- 酒石酸中有害元素的测定要求。     

应用超声三血管气管切面诊断胎儿主动脉弓异常

目的　研究超声三血管气管切面对于胎儿主动脉弓异常的诊断价值。方法　回顾性分析2010年5月至2014年5月北京协和医院诊断的17例胎儿主动脉弓异常的产前超声图像资料，并与产后超声及病理结果进行对照，分析不同类型主动脉弓异常的产前超声特征，重点关注三血管气管切面的表现。结果　17例主动脉弓异常在三血管气管切面均有阳性表现。其中主动脉弓缩窄3例，表现为主动脉弓细小；主动脉弓离断7例，表现为主动脉变细，不能连接至降主动脉；右位主动脉弓合并迷走左锁骨下动脉5例，可见环绕气管的“U”形血管环；右位主动脉弓合并镜像分支2例，可见主动脉弓位于气管右侧，动脉导管不汇入降主动脉。结论　三血管气管切面是提示胎儿主动脉弓异常敏感且有效的切面，中孕超声筛查时应重视该切面，早期发现异常并给予适当的遗传咨询。     

Self‐adaptive 3D pairwise view registration by surface‐fitting and hill‐climbing method

A self‐adaptive 3D pairwise view registration method is presented. Coarse registration of neighboring views is achieved according to their common continuous nonflat areas. These areas are calculated by local least‐square (LS) surface fitting. Then, the principle of point‐to‐surface projection is used to search for the corresponding points, where the local moving least‐square (MLS) surface is employed. Finally, multidimensional optimization based on the technique of hill‐climbing is performed to refine the coarse registration. Experimental results show that this method gives good noise immunity and requires simple computation process and very few manual interventions. Thus it is suitable for large‐scale free‐form surfaces lacking obvious geometric characteristics. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Predicting construction firm performance: an empirical assessment of the differential impact between industry‐ and firm‐specific factors

It is obvious that the performance of firms hinges upon the dynamics of both industry‐ and firm‐specific factors. A less obvious, and perhaps a more important, line of inquiry is that to the extent that they have a bearing on firm performance, how much do these two groups of factors respectively predict firm performance? To date, performance differences among construction firms that stem from industry‐ and firm‐specific differential effect has remained largely unexplored. Using a dataset comprising 526 firms across various construction‐related sectors, the sector‐by‐sector firm performance variation that is attributable to the heterogeneity of both industry‐ and firm‐specific characteristics was empirically examined. That statistically significant results of different effect sizes are found indicates that although these factors are often assumed to be intertwined it is possible to study their respective impact on firm performance. Future studies could usefully replicate and extend this study to construction firms in other countries to further investigate what drives firm performance under different national, industry and firm contexts.     

不同比对方式下的洲际标准时间复现性能分析

中国科学院国家授时中心研制的标准时间复现系统具备支持洲际用户对标准时间频率信号的需求。 本文以位于欧洲 白俄罗斯明斯克的复现终端为分析对象,分析了共视、全视不同比对方式对复现时频信号性能的影响。 对于洲际范围的时间复 现,复现终端与参考端共同可视卫星数变少。 单一卫星导航系统可利用的共视卫星数明显减少,GPS / BDS 共视可明显增加可 视卫星数量,提高共视时间比对精度,全视比对对两地共同可视卫星数没有要求。 分析结果表明,单 GPS 全视比对就可以达到 优于 GPS / BDS 的共视比对复现效果。 受 BDS 卫星星间偏差的影响,基于单 BDS 全视比对的复现效果比 GPS 稍差,GPS / BDS 全视比对效果略有改善。 复现终端运行在 GPS / BDS 共视比对融合 GPS 全视比对模式复现的时频信号的性能最优,可以满足 洲际范围内 5 ns 的时间同步要求,为后续洲际大尺度范围的标准时间复现终端的运行模式提供参考。     

基于城市风貌特色为重心的总体规划——以福建省周宁县总体规划为例

本文通过对周宁县总体规划实例的分析、解读,从城市产业规划、城市定位、生态系统构建、空间布局和旅游规划五个总体规划的主要层面探索重塑城市特色之路。     

"模型黄河"工程规划项目综述

为推进治黄现代化进程,黄河水利委员会党组提出了加大治黄科技含量,着力建设“原型黄河”、“数字黄河”和“模型黄河”的科学治黄新理念。通过“模型黄河”工程建设,可以直观地再现“原型黄河”,从而利用实体模拟的方法对黄河的基本规律和治理方案加以研究,并可为“数字黄河”工程建设提供物理参数。“模型黄河”工程建设是一个复杂庞大的系统工程,为使“模型黄河”工程建设作到科学、合理,遵循“立足黄委、多方参与、专家咨询”的原则,编制了《“模型黄河”工程规划》。该规划是在广泛、细致调研的基础上,依据新世纪黄河治理开发与管理的重大需求编制完成的,具有科学性和可操作性,是我国第一部由流域机构制定并得到水利部批复的系统的实体模型建设规划。“模型黄河”工程体系由实体模型系统、测控系统和试验基地等基础设施所组成;其中,模型系统是“模型黄河”工程体系最重要的核心组成部分。在今后《“模型黄河”工程规划》的实施过程中,应制定合理的实施计划,建立完善的运行管理制度,建立信息资源成果共享制度,加强基础研究,加强计量认证体系和模型试验标准化体系建设。     

Biological activities of Solanum paludosum Moric. extracts obtained by maceration and supercritical fluid extraction

Solanum paludosum extracts obtained by maceration (SP-EtOH_CRUDE and SP-EtOH_MARC) and supercritical fluid extraction (SP-SFECO₂) were evaluated. Three extracts with distinct chromatographic profiles were obtained: SP-EtOH_CRUDE, with a complex phenolic composition; SP-SFECO₂, containing methoxylated flavonoids; and SP-EtOH_MARC, which bears mainly polar polyphenols. All extracts were strong antioxidants, as measured using the diphenylpicrylhydrazyl (DPPH) method, xanthine/xanthine oxidase/luminol and iron-induced lipid peroxidation systems. Extracts were also evaluated as modifiers of antibiotic activity in strains of Staphylococcus aureus expressing fluoroquinolone, macrolide and tetracycline efflux proteins. Despite their lack of antibacterial activity, all extracts were able to potentiate antibiotics activities by as much as eight fold. Both the maceration and supercritical fluid extraction processes were adequate to obtain extracts with different biological activities according to their patterns of phenolic compounds. The data suggest that S. paludosum could be a valuable source of antioxidants and putative efflux pumps inhibitors.     

基于MVC模式的对标管理及指标考核系统设计

以一个完整的大中型信息化系统项目的开发设计为例,从项目管理的角度介绍了目前业界以MVC设计模式为代表的一些主流设计思路与理念,同时基于对项目全生命周期的分析,总结了国内企业在信息化过程中普遍存在的一些共性问题,提出了有限制条件的解决方法.