2004-2013年“雨城”雅安的降水日变化特征分析

利用2004-2013年逐小时降水自动观测数据分析了"雨城"雅安降水的日变化特征.结果表明:近10 a来雅安降水主要表现出单峰型分布特征, 峰值出现在北京时间24:00, 谷值出现在15:00, 夜间降水占年总降水量的74.5%; 降水出现频次也呈现单峰型分布, 峰值出现在01:00, 谷值出现在14:00, 夜间降水次数占全年总次数的66%; 23:00-02:00是雅安最易发生降水的时段, 14:00-16:00 则是最不易出现降水时段. 降水量和降水出现频次日变化形势均表明, 雅安一年四季都具有显著的夜雨特征. 近10 a来, 雅安6 h以上的长持续时间降水事件主要发生在17:00-04:00, 产生的过程降水量占总降水量的80.4%, 对雅安降水总量的贡献占有绝对优势; 持续时间≥24 h的降水事件10 a 累计次数达到74次, 累积降水量达到2 166.8 mm, 占总降水量的14%, 是长持续时间降水事件中对总降水量贡献最大的, 该类事件的影响值得关注.     

Back analysis of an operating subsea tunnel considering the degradation of ground and concrete lining

ABSTRACT

An evaluation of the stability of subsea tunnels during operation is very important considering the risks involved with subsea tunnels. Although a large volume of monitoring information can be obtained, back analysis has been performed based on the internal displacement. In this study, the efficiency of an estimation of the safety of an operating subsea tunnel has been improved by implementing the back analysis algorithm based on various monitoring information. The differential evolution algorithm was adopted for back analysis of an operating subsea tunnel. The differential evolution algorithm was improved to accommodate the multiple target variables for back analysis, such as the elastic modulus, cohesion, friction angle of the ground, and the time-dependent elastic modulus of concrete lining. In addition, the elastic modulus of the concrete lining and the properties of reinforced ground can be evaluated with the proposed algorithm using a range of monitoring data, such as the internal displacement and stress acting on the lining. In summary, back analysis with a differential evolution algorithm can be used to evaluate the stability of an operating subsea tunnel.     

载体角运动对旋转调制惯导系统误差影响分析

针对典型的双轴转停旋转调制系统,从捷联惯导姿态角误差方程出发,理论分析了载体角运动对旋转调制效果的影响。刻度系数误差导致的直流分量误差可等效为不可调制的常值陀螺漂移,对系统的精度水平有较大影响。安装误差导致的交流分量误差可等效为周期振荡的陀螺仪漂移,对系统精度影响较小。仿真结果有效验证了相关分析结论。     

加拿大极地通信和气象卫星计划分析

北极是全球气候敏感区域之一,长期以来极地气象观测资料比较缺乏.为了提高北美及全球天气预报的准确性,加拿大航天局联合加拿大环境、气象、国防等部门多个单位共同启动了极地通信和气象卫星(PCW:Polar Communication and Weather)计划,持续提供50°N以北地区的通信服务和气象遥感观测.在气象方面,PCW将提供北极极地附近地区每隔15/30min的多光谱遥感信息,重点用于高纬度风场反演、海/湖冰、积雪和植被监测,云、气溶胶和火山灰信息反演,这些遥感信息在气候变化研究中将发挥重要作用.简要介绍了PCW计划的进展、卫星观测系统设计、轨道设计、遥感仪器、气象和空间天气的监测产品及应用.     

焦化厂的防雷防静电措施及防雷检测

以焦化的生产工艺流程为主线索,介绍了焦化厂各生产环节所需采取的防雷防静电措施及对焦化厂进行防雷检测时的注意事项.     

海拉尔盆地贝尔凹陷南部层间构造及岩性圈闭的三维地震解释

应用Landmark工作站SeisWorks地震解释和Geopmbe三维可视化模块,以构造、岩性圈闭识别和储层预测等技术为手段,对海拉尔盆地敖瑙海地区主要勘探目的层系内部的层间构造和岩性圈闭进行了精细解释.由已知井出发,确定层间构造的油层顶面位置并进行层位追踪.利用相干数据体以及相干体水平切片、相干体沿层切片技术对三维资料进行断层解释,最终编制出油层顶面构造图完成层间构造解释.利用Geoprobe三维可视化全方位浏览数据体、体透视、种子点追踪、层拉平及反拉平技术完成岩性圈闭解释.通过对层间构造和岩性圈闭进行精细刻画,为探井部署提供了可靠依据.经钻探,多口探井见到较好的油气显示并获工业油流,为贝中次凹提交6 73×10⁴t石油预测储量奠定了坚实基础.     

Influence of the Three Gorges Project on saltwater intrusion in the Yangtze River Estuary

The Three Gorges Project (TGP) is a transcentury project that has aroused world attention. It is expected that the flow velocity and runoff of the Yangtze River will be changed after the project has been accomplished. Consequently, however, the ecological environment in the Yangtze River Basin, particularly in the estuary region, will be affected. Salinity intrusion into the Yangtze River estuary, in general, is mostly affected by the Yangtze River discharge and its external tidal level. This paper focuses on examining the influence of changes in runoff on salinity value. The question, to which should be paid attention is: how is the interaction between changes in runoff of the Yangtze River and salinity distribution in the Yangtze River estuary, China? In this research, a three-dimensional model has been used to identify the effects of runoff change on salinity distribution. The drawn conclusion is that the change of salinity is influenced by discharge variation. Positive and negative impacts of TGP would both turn up but in different period. In sum, TGP is in favor of restraining saltwater intrusion. Nevertheless a suitable method should be found to resolve its negative influences.     

Heavy metals and polychlorinated biphenyls in sediments of the Yangtze river estuary,China

Typical pollutants in sediments from 22 sampling sites of the Yangtze river estuary in 2006 were investigated in the present study. Arsenic, mercury, cadmium, copper, chromium, zinc, lead, and polychlorinated biphenyls of the Yangtze river estuary sediments were found as 6.49–17.6, 0.0164–0.0987, 0.059–0.319, 11.7–46.6, 10.5–113, 44.5–125, 14.8–32.7, and 0.0006–0.0026 mg/kg, respectively. Results indicated the presence of a contamination in the Yangtze river estuary. Through analyzing the contents of typical pollutants in sediments with adopting the index number techniques of Muller geoaccumulation index and Hakanson ecological risk factors and index, the quality status of these sediments were evaluated. Furthermore, the potential ecological risks of the estuary were determined quantitatively. The overall environmental quality of typical pollutants was generally in a good condition in most sites. The results showed that arsenic was the main environmental pollution factor, and cadmium was the main potential ecological factor. The highest potential ecological risk index appeared in the south branch of the Yangtze river, which was mainly due to terrestrial pollution in Shanghai. The results of this study can be used for decision makers to prioritize measures to control the pollution for these typical pollutants.