高强钢筋增强UHPC-NC组合柱抗震性能研究

为探讨高强钢筋增强UHPC-NC组合柱抗震性能,基于大型有限元程序ABAQUS,结合UHPC、NC和高强钢筋材料本构关系,校准损伤塑性模型中相关参数,建立高强钢筋增强UHPC-NC组合柱抗震有限元模型。通过与3个NC柱和3个UHPC柱拟静力试验结果对比,验证分析模型的有效性。在此基础上,进一步探讨轴压比、纵筋直径、纵筋强度、箍筋间距和UHPC高度等敏感参数对高强钢筋增强UHPC-NC组合柱抗震性能的影响。结果表明,高强钢筋增强UHPC-NC组合柱位移延性系数随轴压比、纵筋直径和箍筋间距的增大而降低,随纵筋强度和UHPC高度的增加表现出先增大后逐渐平缓的趋势,合适的UHPC替换高度能充分发挥高强钢筋和UHPC材料特性并取得良好的经济性。     

Analysis of the microseismicity characteristics in landslide dam failure flume tests: implications for early warning and dynamics inversion

Landslides - Determining the premonitory and dynamic characteristics of landslide dam failures can provide an early warning as well the identification of the evolution of the failure process, and...     

乌鲁木齐市建设用地全程管理系统分析与设计

建设用地全程监管工作是促进节约集约用地的重要手段,而建设建设用地全程管理系统则是有效落实建设用地全程监管工作的的重要工具。结合乌鲁木齐市国土资源局信息化现状及建设用地业务需求,分析了建设用地业务及内容,提出了系统的建设目标、建设思路、总体框架、功能结构。     

条件非线性最优扰动在可预报性问题研究中的应用

本文总结了近年来条件非线性最优扰动方法的应用研究的主要进展.主要包括四个方面:(1)将条件非线性最优扰动(CNOP)方法拓展到既考虑初始扰动又考虑模式参数扰动,形成了拓展的CNOP方法.拓展的CNOP方法不仅能够应用于研究分别由初始误差和模式参数误差导致的可预报性问题,而且能够用于探讨初始误差和模式参数误差同时存在的情形;(2)将拓展的CNOP方法分别应用于ENSO和黑潮可预报性研究,考察了初始误差和模式参数误差对其可预报性的影响,揭示了初始误差在导致ENSO和黑潮大弯曲路径预报不确定性中的重要作用;(3)考察了阻塞事件发生的最优前期征兆(OPR)以及导致其预报不确定性的最优增长初始误差(OGR),揭示了OPR和OGR空间模态及其演变机制的相似性及其局地性特征;(4)研究了台风预报的目标观测问题,用CNOP方法确定了台风预报的目标观测敏感区,通过观测系统模拟试验(OSSEs)和/或观测系统试验(OSEs),表明了CNOP敏感区在改进台风预报中的有效性.具体地,台风OGR的主要误差分布在某一特定区域,空间分布具有明显的局地性特征,在台风OGR的局地性区域增加观测,有效改进了台风的预报技巧,该区域代表了台风预报的初值敏感区.事实上,上述El Ni(n)o事件、黑潮路径变异以及阻塞事件的OGR的空间分布也具有明显的局地性特征,这些事件的OGR刻画的局地性区域可能也代表了初值敏感区.     

Investment risk and return under renewable decarbonization of a power market

How does financial performance risk affect investments in low-carbon electricity-generating technologies to achieve climate policy targets? A detailed risk simulation of price formation in the Great Britain wholesale power market is used to show that the increasing replacement of fossil facilities with wind, ceteris paribus, may cause a deterioration of the financial risk–return performance metrics for incremental investments. Low-carbon investments appear to be high risk, low return, and as such may require a progressively higher level of support over time than envisaged by the conventional degression trajectories. The increasing riskiness of the wholesale market will to some extent offset the benefits of lower capital costs and operational efficiencies if investors need to satisfy cautious debt coverage ratios alongside positive expected returns. This increased risk is additional to the well-known ‘merit order effect’ of low-carbon investments progressively depressing wholesale prices and hence their expected investment returns.

Policy relevance

Policy support for renewable technologies such as wind is usually based upon levelized costs and is expected to reduce over time as capital costs and operational efficiencies improve. However, levelized costs do not take full account of the risk aversion that investors may have in practice. Expected policy support reductions may be moderated to some extent by the increased financial performance risk that intermittent technologies bring to the power market. The annual risk-return profiles for incremental investments deteriorate for all technologies as wind replaces fossil fuels. This extra risk premium will need to be incorporated into evaluating policy incentives for new investments in a decarbonizing power market.     

重庆强对流短临业务评分方法

结合重庆本地实际情况,以区/县为单位对强对流中出现的短历时强降水、阵性大风及雷电进行业务质量定量评估.短历时强降水、阵性大风基于加密站观测资料采用分级的方式来评定,对雷电的评定基于ADTD系统观测到地闪资料并判断所在区/县是否有地闪出现.介绍了重庆本地强对流短临业务评分方法及开发的评分软件.从2011年的评分结果看,该评分方法在重庆本地是比较合理的,在业务应用上是可行的.     

A new lunar absolute control point: established by images from the landing camera on Chang'e-3

The establishment of a lunar control network is one of the core tasks in selenodesy, in which defining an absolute control point on the Moon is the most important step. However, up to now, the number of absolute control points has been very sparse. These absolute control points have mainly been lunar laser ranging retroreflectors, whose geographical location can be observed by observations on Earth and also identified in high resolution lunar satellite images. The Chang'e-3(CE-3) probe successfully landed on the Moon, and its geographical location has been monitored by an observing station on Earth. Since its positional accuracy is expected to reach the meter level, the CE-3 landing site can become a new high precision absolute control point. We use a sequence of images taken from the landing camera, as well as satellite images taken by CE-1 and CE-2, to identify the location of the CE-3 lander. With its geographical location known, the CE-3 landing site can be established as a new absolute control point, which will effectively expand the current area of the lunar absolute control network by 22%, and can greatly facilitate future research in the field of lunar surveying and mapping, as well as selenodesy.     

我国恐龙空间分异原因初探

本文讨论了中国境内先后出现的恐龙动物在古地理位置、分布范围上的变化特点，提出引起中国恐龙空间分异的主要原因是占地理环境的巨大变迁，同时也与占气候、占植物的变化有密切关系。并进一步指出，中国恐龙绝灭的原因应该是突发的灾变。     

农田生态系统中重金属的积累积循环

本文通过对北京东郊高碑店地区污染农田的调查研究,探讨了重金属在农田生态系统中的积累和循环,计算出重金属在区域环境中的输入输出量,说明本区仍处于重金属积累状态,为防治农田环境污染,提出了停止施用污水处理厂的晾干污泥,减少灌溉污水中的重金属含量等保护性措施。     

The Impact of Horizontal Resolution on the CNOP and on Its Identified Sensitive Areas for Tropical Cyclone Predictions

In this study,the impacts of horizontal resolution on the conditional nonlinear optimal perturbation (CNOP) and on its identified sensitive areas were investigated for tropical cyclone predictions.Three resolutions,30 km,60 km,and 120 km,were studied for three tropical cyclones,TC Mindulle (2004),TC Meari (2004),and TC Matsa (2005).Results show that CNOP may present different structures with different resolutions,and the major parts of CNOP become increasingly localized with increased horizontal resolution.CNOP produces spiral and baroclinic structures,which partially account for its rapid amplification.The differences in CNOP structures result in different sensitive areas,but there are common areas for the CNOP-identified sensitive areas at various resolutions,and the size of the common areas is different from case to case.Generally,the forecasts benefit more from the reduction of the initial errors in the sensitive areas identified using higher resolutions than those using lower resolutions.However,the largest improvement of the forecast can be obtained at the resolution that is not the highest for some cases.In addition,the sensitive areas identified at lower resolutions are also helpful for improving the forecast with a finer resolution,but the sensitive areas identified at the same resolution as the forecast would be the most beneficial.