无伸缩缝桥梁研究综述

综述了无伸缩缝桥梁(简称“无缝桥”)技术发展,介绍了无缝桥优点、应用和研究热点,分析了无缝桥纵桥向受力特点、桩-土相互作用、台后土压力与抗震性能,指出了新技术研发与应用的现状与发展方向。分析结果表明：无缝桥技术受到许多国家的重视,已开展了大量的实桥监测和其他研究;在纵桥向受力方面,温度变形是其主因,现有规范中所给出的平均温差与实桥监测结果相差较大,应研究精度更高的计算方法;桩-土相互作用是整体桥受力的特点与研究的难点,在计算土抗力时,m法应限于小位移的无缝桥,位移较大时宜采用p-y曲线法;桥台桩基受力复杂,H型钢桩存在屈服、疲劳、屈曲的破坏可能,混凝土桩则易出现开裂病害;无缝桥温升时台后土压力增大,是研究的热点与难点,它随水平变形量和往复变形次数增大而增大的机理、量值和分布未达成共识,有待今后深入、系统的研究;纵桥向受力分析应建立全桥有限元模型,考虑结构-土相互作用和节点非线性性能;钢主梁受压稳定性和混凝土主梁抗裂性能是研究与设计的关键;引板是无缝桥的病害易发构件,面板式引板应减小板底摩阻力,避免开裂和末端沉降,而斜埋入式引板应控制其末端之上接线路面的隆起和下陷;许多无缝桥新技术已被提出并得到应用,今后还需深入研究,如：新材料与新构造在无缝桥各组成部分、台背、桩基与引板中的应用等;无缝桥具有较强的结构强健性、抗倒塌和防落梁能力,抗震研究已取得可喜的进展,但许多国家尚未形成相关的设计规定,应继续研究,为将来的应用和规范制订提供科学依据。     

Sustainability perspectives when crop use is implemented in different sectors: A life cycle assessment approach

The present study aims to provide a preliminary overview of the sustainability concept when biomasses conceived for food goals become the raw materials upon which different sectors, such as plastic or energy industry, can develop innovative strategies, according to a so called ??greener?? competitiveness. In the results hereafter presented, the definition of sustainability perspectives, according to the use of a life cycle assessment (LCA) approach, will be described for maize use as raw material in different sectors. The current biopolymer industry and conventional biofuel technologies, the so called first-generation biofuels, are the more and more in competition with the food sector. The presented environmental evaluation, in terms of air emissions, energy and water consumption, is useful in order to understand the sustainability of a bio-sourced product, in comparison with the equivalent item produced by fossil fuels.     

Stated adaptation surveys and choice process: Some methodological issues

The "Stated Adaptation" survey is an interactive technique which allows us to obtain a clearer picture of the attitudes and behaviours of individuals when confronted with hypothetical situations, in particular inexperienced travel conditions. This method makes use of a simulation game whose purpose is to explore on small samples individuals' choice processes when selecting between the different transport alternatives which are available to them. This paper describes how gaming-simulation is designed, with reference to the issues tackled by two surveys which have recently been carried out in France (reactions to urban road pricing and perception of electric vehicles). It describes the benefits of this experimental approach which allows stated behaviours to be checked to a considerable degree. The limits and potential developments of this survey technique are also discussed.     

Driver-Vehicle-Lateraldynamics under Regular Driving Conditions

In order to minimize accidents and achieve comfortable handling it is necessary to analyse the control behaviour of the driver-vehicle system and adapt the vehicle to the driver. However, most of the tests have shown, that under normal driving conditions the driver adapts himself to the vehicle, which is exactly the other way round as it was originally thought. In this paper it would be shown, how the driver adapts himself to the vehicle and which technical parameters may effect this adaptation.     

Transit costs and cost efficiency: Bootstrapping non-parametric frontiers

This paper explores a selection of recently proposed bootstrapping techniques to estimate non-parametric convex (DEA) cost frontiers and efficiency scores for transit firms. Using a sample of Norwegian bus operators, the key results can be summarized as follows: (i) the bias implied by uncorrected cost efficiency measures is numerically important (close to 25%), (ii) the bootstrapped-based test rejects the constant returns to scale hypothesis, and (iii) explaining patterns of efficiency scores using a two-stage bootstrapping approach detects only one significant covariate, in contrast to earlier results highlighting, e.g., the positive impact of high-powered contract types. Finally, comparing the average inefficiency obtained for the Norwegian data set with an analogous estimate for a smaller French sample illustrates how the estimated differences in average efficiency almost disappear once sample size differences are accounted for.     

Analysis Method of Head-on Vehicle Collision

In this paper a method of analysis of vehicle head-on collision, based on the concept of dispersion of stress waves in rods upon axial impact has been presented. The mathematical model of collision studied here described the vehicle behaviour in collision in terms of a one-dimensional, nonhomo-geneous, nonlinear partial differential equation. A procedure of model identification and some remarks concerning experimental data have been discussed. Results of computer simulation of a tested vehicle have been given.     

微小核糖核酸

最近几年中，微小核糖核酸和基因转录后调节领域出现了飞快的发展。微小核糖核酸．或缩写为miRNA，是小的．调节性核糖核酸，它与小的干扰核糖核酸（SiRNA）类似．但它是体内天然表达的。     

The Decline of the Artisanal Fisheries in Mediterranean Coastal Areas: The Case of Cap de Creus (Cape Creus)

This article examines the sociocultural, economic, and environmental causes of the decline of the artisanal fisheries in the rocky coast of Cape Creus (NW Mediterranean) over the past decades. The changes that have occurred over time have favored trawlers, purse-seiners, shellfish fisheries, and tourism activities, to the detriment of artisanal fisheries. This article shows that the establishment of a marine reserve in 1998 could not reverse the observed decline in the artisanal fisheries. This raises the necessity of implementing a fishery management plan integrated into a coastal management plan, which should accompany the habitat protection. These plans could assist in the maintenance and the sustainable development of the artisanal fishing sector in Cape Creus as well as in other Mediterranean coastal areas where artisanal fisheries are also declining.     

应用Q-DAS CAMERA~ Concept提升企业精益生产水平 基于工业产品质量数据的绩效评价系统开发与运用

Q-DAS CAMERA~ Concept支持柔性和模块化应用,既可以应用于单个工作场所,也可为部门级、工厂级或区域级的综合系统提供解决方案。     

地铁运营与第三方督查

据2011年11月22日《解放日报》报道,在上海市人大代表座谈会上,有代表建议人大加强对地铁建设、运行等重大工程、重大项目的监督,地铁运营方须引入第三方督查机制,聘请国内、国外专家,对地铁运行系统“从头开始查”,“一个系统一个系统地查”.对此我很有同感,因为有没有第三方督查,对于系统的安全性,其效果是大不一样的.