Gulf Stream density structure and transport during the past millennium

The Gulf Stream transports approximately 31 Sv (1 Sv = 10(6) m(3) s(-1)) of water and 1.3 x 10(15) W of heat into the North Atlantic ocean. The possibility of abrupt changes in Gulf Stream heat transport is one of the key uncertainties in predictions of climate change for the coming centuries. Given the limited length of the instrumental record, our knowledge of Gulf Stream behaviour on long timescales must rely heavily on information from geologic archives. Here we use foraminifera from a suite of high-resolution sediment cores in the Florida Straits to show that the cross-current density gradient and vertical current shear of the Gulf Stream were systematically lower during the Little Ice Age (ad approximately 1200 to 1850). We also estimate that Little Ice Age volume transport was ten per cent weaker than today's. The timing of reduced flow is consistent with temperature minima in several palaeoclimate records, implying that diminished oceanic heat transport may have contributed to Little Ice Age cooling in the North Atlantic. The interval of low flow also coincides with anomalously high Gulf Stream surface salinity, suggesting a tight linkage between the Atlantic Ocean circulation and hydrologic cycle during the past millennium.     

导流管束对风速传感器管道风速场的影响

为了保证某公司新型风速传感器管道送风的均匀度和稳定性,提出了利用导流管束代替均流孔板的方法,并采用CFD软件FLUENT对不同风速条件下,无均流措施、采用均流孔板和采用导流管束3种工况下的风速场分别进行了模拟,并搭建了管道送风测试实验台,利用新老2种风速传感器对加装导流管束前后的管道风速场进行了对比测试。理论分析和实验结果均表明,在管道送风条件下加装导流管束完全能够达到均流和稳流的作用,是比较经济、省时和合理的方法。     

汽轮机凝汽器真空降低对机组运行的影响分析

分析了凝汽器真空降低对机组运行的影响,针对凝汽器真空下降的原因提出改进措施,以提高机组效率。     

银幕上的旋律流程--中国电影音乐创作浅谈

中国电影音乐的探索始自20世纪30年代至50年代直至60年代,中国电影音乐趋向成熟,交响曲的语言在电影音乐中运用极为普遍;而20世纪80年代至90年代的中国电影音乐已步入辉煌,在音乐所具有的时间上的连贯性和结构上的完整性把握得恰到好处,音乐的色彩和电影的色彩在大师级的作品中往往得到了完美结合。     

流媒体技术刍议

在互联网迅速发展的时代,视频技术在越来越多的场所发挥着“运筹于帷幄之中,决胜于千里之外”这一特色功效,而幕后的英雄就是流媒体．基于流媒体的概念,简要介绍了流媒体的技术及其应用．     

吸气喷液对空气源热泵热水器性能的影响

通过对采用吸气喷液的热泵热水器循环过程进行理论分析,建立了压缩机吸气温度、排气温度、机组制热量、功耗及能效比等性能参数与吸气喷液量的关系,研究了不同喷液量对机组性能参数的影响.试验分析了不同运行工况下,吸气喷液引起的热泵热水器性能参数变化趋势,并与计算结果进行了对比分析.研究表明:采用吸气喷液对降低压缩机排气温度具有比较明显的效果,但同时也降低了机组制热量和能效比,提高了功耗;喷液量比例应该控制在5%以下;吸气喷液对于热泵热水器在低环境温度下运行具有较好的综合效果;在环境温度低于20℃运行时,采用吸气喷液可以降低压缩机排气温度10℃以上,机组制热量下降幅度小于5%,功耗上升幅度小于1.5%,能效比降低幅度低于7%.     

Atmospheric science: stratospheric cooling and the troposphere

Satellite observations of tropospheric temperatures seem to show less warming than surface temperatures, contrary to physical predictions. Fu et al. show that statistical correction for the effect of stratospheric cooling brings the satellite-based estimates of tropospheric warming into closer agreement with observations of surface warming. Here we apply the method of Fu et al. to output from a state-of-the-art coupled climate model and show that simulated tropospheric temperature trends are consistent with those observed and that their method is robust.     

杭州湾大通道及港口建设对宁波市物流的影响

文章阐述了宁波港口货运的现状、存在问题和发展趋势，杭州湾大通道建成后对宁波市货运物流、集装箱运输、货运成本、经济腹地等方面的影响。     

分布式视频编码

随着网络的发展和无线视频的应用,分布式视频编码(DVC)理论越来越受到大家的重视.本文主要介绍了分布式视频编码的理论基础及其应用方法,并简要介绍了目前该领域的研究方向和成果.     

浅析Delphi编程中的流

介绍Delphi编程中流的基本知识和原理，以及在实际开发应用中如何利用Delphi中的流来实现数据存取等功能．     

Observational responses of stratospheric sudden warming to blocking highs and its feedbacks on the troposphere

The influences of tropospheric blocking high on the stratospheric sudden warming (SSW) and the SSW-induced feedback on the lower atmosphere are analyzed with NCEP (National Center for Environmental Prediction) 2 reanalysis data. Daily mean data from 1979 to 2010 are used to perform statistical and dynamical analyses. According to different distribution features of polar vortex, which can be ascribed to different activities of blocking highs, we have obtained two warming patterns in vortex splitting and displacement patterns. For vortex splitting events, in the Eurasian-North American (ENA) paratype, with disturbances of Atlantic and Aleutian blocking highs, polar vortex is split into two parts that locate at Eurasian and North American continents respectively, while in the Atlantic-East Asian (AEA) paratype, two low-pressure centers derived from the split vortex are situated in the Atlantic and East Asian regions, and two blocking systems occurring in the Urals and North American areas precede these splitting processes. For vortex displacement events, in the Aleutian-Intrusion (AI) paratype, the polar vortex is displaced to the west European and Atlantic areas by the intrusive Aleutian high and this pattern always corresponds to the blocking events occurring in the Pacific basin only. Similarly, the vortex is pushed to the west Eurasian continent by the intrusive North American high-pressure system in the North American-Intrusion (NAI) paratype, which is closely related to the blocking over these areas. The second subject of the research is that whether the anomalous stratospheric signals can be propagated to the lower atmosphere, which is depended on the intensity, duration and position of the disturbed vortex. According to our case studies, geopotential height anomalies can be propagated to the troposphere in strong SSW years, taking about 10-15 d for the decrease from 10 to 500 hPa, leading to apparent variations in the geopotential height and temperature fields.     

流媒体技术综述

由于网络硬件设备的发展跟不上人们需求的提高,因此流媒体技术应运而生。本文介绍了流媒体传输的特点、协议、格式,流媒体系统的组成,流媒体技术与传统广播电视的结合及流媒体技术的应用前景。     

数据流挖掘技术

简要概述了数据流挖掘技术，探讨了数据流的特点．数据流的概念漂移现象，给数据流上的数据挖掘带来很大困难．由于计算机的内存有限，数据窗口技术只针对最近的数据，而最近的数据常常导致数据挖掘系统中的分类器过配，文中介绍了解决这一问题的方法，并讨论了数据流挖掘技术的应用．     

北部湾潮汐数值计算参数的试验

选不同的海底摩擦系数以及水平湍流摩擦系数，对北部湾的ｋｉ分潮进行了数值模拟试验。结果表明，当底摩擦系数取０．００２～０．００３，而水平湍流摩擦系数取１×１０２～５×１０３ｍ２／ｓ时其模拟结果与实测潮波系统比较吻合。潮波动力学方程中的底摩擦项对数值结果影响较大，而水平湍摩擦项对数值结果的影响不甚明显。     

面向网络数据流的持续查询

有别于传统的存储型数据静态查询,构造了一种对网络数据流进行持续查询的模型．该模型提供了映射和转化机制,兼容了数据流“时序”概念和传统数据库中的“关系”概念。     

MPEG-2节目流到数字电视传输流的转换系统

为了给数字电视广播提供丰富的节目源,作者研究并实现了一个从MPEG-2节目流到数字电视传输流的转换系统．文中首先介绍了MPEG-2节目流和数字电视广播所使用的传输流的结构,在此基础上提出了具体的转换系统实现方案,并对其中涉及的一些关键技术作了详细的讨论．实时播放分析和离线分析的结果都表明,本系统可以正确、稳定地实现码流的转换．     

十八重溪野生植物资源的研究

在调查研究的基础上，笔者统计了十八重溪维管束植物，计有１５９科，４７９属，８２９种。其中蕨类植物３５科，５３属，９３种；裸子植物６科，６属，６种；被子植物１１８科，４２０属，７３０种，在调查的基础上，分析了种子植物各属的区系成分。根据野生经济植物的用途，把区内野生经济植物分为８类：油脂植物、淀粉及糖类植物、芳香油植物、纤维植物、鞣料植物、观赏植物、药用植物和蜜粉源植物。在此基础上。提出野生经济植物合理利用与保护的设想，为进一步研究十八重溪野生经济植物，以及植物资源合理利用与保护提供基础资料和科学依据。