都汶高速公路庙子坪岷江特大桥震后5号主墩加固技术

都汶高速公路是成都通往汶川的重要的交通枢纽,为国道213和317合线。都汶高速公路庙子坪岷江特大桥(又名紫坪铺大桥)直接跨越紫坪铺水库和岷江,都江堰端接著名的董家山高瓦斯隧道,汶川端接龙洞子隧道。5.12汶川大地震对庙子坪岷江特大桥产生了不少震害,地震后大桥的加固时间紧、工作量大、技术复杂,这在中国乃至世界桥梁史上前所未有;特别是5号主墩加固异常复杂和艰难,从桥面防撞护栏顶面到5号主墩地面承台顶面之间总体落差114.488 m,5号主墩地面承台顶面到水面水深达65 m。通过对5号主墩承台顶面以上14 m加固区间(全部位于深水区域)的潜水堵孔和钢沉箱工艺进行深入细致的研究,制定了系列相应措施。     

上海虹桥综合交通枢纽西航站楼三角形屋架预应力施工技术

上海虹桥国际机场是我国三大枢纽机场之一,该扩建工程西航站楼部分屋面采用预应力张弦结构。结合工程实际,着重论述了部分结构的预应力施工,并结合施工仿真和现场实测,提出了此类结构的预应力施工技术的关键。     

Perceptual-based quality assessment for audio–visual services: A survey

Accurate measurement of the perceived quality of audio–visual services at the end-user is becoming a crucial issue in digital applications due to the growing demand for compression and transmission of audio–visual services over communication networks. Content providers strive to offer the best quality of experience for customers linked to their different quality of service (QoS) solutions. Therefore, developing accurate, perceptual-based quality metrics is a key requirement in multimedia services. In this paper, we survey state-of-the-art signal-driven perceptual audio and video quality assessment methods independently, and investigate relevant issues in developing joint audio–visual quality metrics. Experiments with respect to subjective quality results have been conducted for analyzing and comparing the performance of the quality metrics. We consider emerging trends in audio–visual quality assessment, and propose feasible solutions for future work in perceptual-based audio–visual quality metrics.     

On the Morphology,Structure and Field Emission Properties of Silver-Tetracyanoquinodimethane Nanostructures

Silver-tetracyanoquinodimethane(Ag-TCNQ) nanostructured arrays with different morphologies were grown by an organic vapor-transport reaction under different conditions. The field emission properties of nanostructured arrays were studied systematically. Their morphology and crystal structure were characterized by SEM and XRD, respectively. It was found that the field emission properties were strongly dependent on the reaction temperature and the initial Ag film thickness. The lowest turn-on field with 10-nm-thick silver film is about 2.0 V/μm, comparable to that of carbon nanotubes. The film crystal structure and the morphology are contributed to the final emission performance.     

浅谈硒腐植酸钠在水产上的应用

硒腐植酸钠复合了多种有效成分,通过物理、化学作用,吸附和凝聚水中有机物及悬浮物,螯合重金属离子,氧化水体中的氨氮、硫化氢等有毒物质,可迅速将有害的物质去除,转化为有益生物,起到改善底层养殖环境的作用,在水产养殖中具有广泛应用。     

城市景观规划中的文化脉络与地域特征——以杭州市余杭创新基地生态核心区景观规划为例

全球化的时代大背景,导致城市地域特征与文化多元性不断弱化甚至丧失,景观趋同现象尤为严重,世界各国的城市都面临着不同程度的景观危机。特别是我国经济社会飞速发展,在外来文化的冲击下,城市景观变得越来越特色缺失、千景一面,其根本原因在于,城市景观规划忽略了本地的文化内涵和地域特征。本文以杭州市余杭创新基地生态核心区景观规划为例,以"自然生态"和"科技创新"为切入点,促使两者有机生长,从基地文化脉络与地域特征两个层面入手,旨在通过具体的表现手法和方案特点的总结,探讨城市景观规划的一些基本方法和途径。     

轨道交通路基段施工技术

介绍了北京市轨道交通亦庄线工程悬臂式混凝土挡土墙路基的相关设计及施工技术,并针对施工过程中存在的相关问题提出了改进措施。     

云南省1998年～2003年家庭进餐引起的食物中毒分析

为做好家庭进餐食物中毒的预防工作，对云南省1998年至2003年家庭进餐引起的食物中毒情况进行分析。6年间全省共发生家庭进餐所引起的食物中毒286起、发病3592人、死亡165人；占同期全部食物中毒起数、发病人数、死亡人数的53．16％、29．05％、93．75％，中毒起数逐年上升，中毒食品以植物性食品居首，植物性食品以误食毒草造成的中毒居首，农村婚、丧事家庭进餐引起的中毒发病人数多。加大食品安全宣传工作，破除陈规陋习，不断改善群众的卫生意识和卫生习惯，提高全社会对食品安全知识的知晓率，是预防家庭进餐引起食物中毒的重要措施。