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排序方式: 共有1002条查询结果,搜索用时 31 毫秒
991.
Nayruti Siddharth Trivedi Murali Sankar Venkatraman Clement Chu Ivan S. Cole 《Climatic change》2014,124(1-2):133-146
As structures built now will be expected to last well past 2064 (50 years) it is vital that the effect of climate change be considered in their design and material selection. In particular changes in the rate of corrosion of metal components must be considered. To this end this study estimates the maximum likely change in the corrosion rate for the year 2070 so it can be included in current design. Changes in corrosion are estimated for 11 coastal and inland locations in Australia. For each station the climatic data (3-hourly) in 2070 is estimated by modifying current data with probable changes based on two climate change models (CSIRO: CSIRO-Mk 3.5 and MRI: MRI-CGCM 3.2.2). The former is for high global warming rate and the later the A1FI scenario. This climatic data is then run the Corrosion “predictor” (a multi-scale process model) to predict corrosion at each location. It is found that significant changes occur with corrosion in coastal locations increasing substantially, in contrast the corrosion at inland locations will decrease moderately. The increase in coastal locations is associated with a greater build up of salt due to less frequent rain evens while the reduction in inland locations is associated with a reduction in RH and thus surface wetness. 相似文献
992.
????JASON1?????????к??????????????????????????????????????ERA??40????????????м????????????????????????CS??????????CSG2???????CSG1????Hwang????ZT???????????????CS?????????????????????????????????????????????????????????????????? 相似文献
993.
The velocity ambiguity in Doppler weather radars has inhibited the application of wind field data for long time. One effective solution is software-based velocity dealiasing algorithm. In this paper, in order to better design, optimize and validate velocity dealiasing algorithms for CINRAD-SA, data from operational radars were used to statistically characterize velocity ambiguity. The analyzed characteristic parameters included occurrence rate, and inter-station, inter-type, temporal, and spatial distributions. The results show that 14.9% of cloud-rain files and 0.3% of clear-air files from CINRADSA radars are ambiguous. It is also found that echoes of weak convections have the highest occurrence rate of velocity ambiguity than any other cloud types, and the probability of ambiguity is higher in winter than in summer. A detailed inspection of the occurrence of ambiguity in various cases indicates that ambiguous points usually occur in areas with an elevation angle of 6.0°, an azimuth of 70° or 250°, radial distance of 50–60 km, and height of 5–6 km, and that 99.4% of ambiguous points are in the 1st-folding interval. Suggestions for performing dealiasing at different locations and different time points are provided. 相似文献
994.
西南印度洋中脊热液产物稀土元素组成变化及其来源 总被引:1,自引:1,他引:0
对西南印度洋中脊热液区不同热液产物稀土元素(REE)进行了分析,探讨了热液产物形成过程中稀土元素组成变化及其来源。研究结果表明:不同热液产物稀土元素总量变化范围从3.47×10-7到4.80×10-5,轻重稀土比值(LREE/HREE)从2.06到6.16,表明轻重稀土有较大程度分异,δEu异常(δEu=0.86~3.88)和δCe异常(δCe=0.40~0.86)显示热液产物中REE呈Eu富集和Ce亏损特征。稀土元素球粒陨石标准化模式呈现两种类型:(1)呈轻微富集LREE的平坦模式,REE大于2×10-5;(2)呈显著富集LREE和正Eu异常模式,REE小于5×10-7。模式1类似于洋壳火山岩REE配分模式,而模式2与西南印度洋中脊黑烟囱REE模式相似,也与典型洋中脊热液喷口流体和硫化物LREE富集和正Eu异常模式类似。热液产物中稀土元素含量变化和模式特征以及Mg与LREE极强正相关关系可能反映了西南印度洋中脊硫化物形成在热液流体与海水混合沉淀的初始阶段,后期经历了广泛的热液流体再循环和海水蚀变过程。 相似文献
995.
Risk assessment development considering the failure of landslide dams often requires the estimation of peak outflow through the breach. The empirical equations based on data from case studies tend to be the first direct approach. This paper conducted an uncertainty analysis when these empirical relations were utilized to predict the peak outflow of a breached landslide dam. The results suggest that the relations derived from manmade dams or embankments typically overestimate the peak outflow about 1/5 to 3/4 of an order of magnitude; and the relations derived from the database of landslide dams have much smaller mean prediction errors and also exhibit broad uncertainty bands. Application of the uncertainly analysis was illustrated by the Tangjiashan landslide dammed lake, formed during 2008 Wenchuan earthquake. In addition, the predicted results from Eq. 1 deduced herein were considered to be the reliable estimate of peak outflow through the breach of landslide dam. 相似文献
996.
K. Zacny S. Nagihara M. Hedlund G. Paulsen J. Shasho E. Mumm N. Kumar T. Szwarc P. Chu J. Craft P. Taylor M. Milam 《Earth, Moon, and Planets》2013,111(1-2):47-77
In this paper, the development of heat flow probes for measuring the geothermal gradient and conductivity of lunar regolith are presented. These two measurements are the required information for determining the heat flow of a planetary body. Considering the Moon as an example, heat flow properties are very important information for studying the radiogenic isotopes, the thermal evolution and differentiation history, and the mechanical properties of the interior. In order to obtain the best measurements, the sensors must be extended to a depth of at least 3 m, i.e. beyond the depth of significant thermal cycles. Two approaches to heat flow deployment and measurement are discussed in this paper: a percussive approach and a pneumatic approach. The percussive approach utilizes a high frequency hammer to drive a cone penetrometer into the lunar simulant. Ring-like thermal sensors (heaters and temperature sensors) on the penetrometer rod are deployed into the simulant every 30 cm as the penetrometer penetrates to the required 3 m depth. Once the target depth has been achieved, the deployment rod is removed from the simulant, eliminating any thermal path to the lander. The pneumatic approach relies on pressurized gas to excavate, using a cone-shaped nozzle to penetrate the simulant. The nozzle is attached to a coiled stem with thermal sensors embedded along the length of the stem. As the simulant is being lofted out of the hole by the escaping gas, the stem is progressively reeled out from a spool, thus moving the cone deeper into the hole. Thermal conductivity is measured using a needle probe attached to the end of the cone. Breadboard prototypes of these two heat flow probe systems have been constructed and successfully tested under lunar-like conditions to approximately 70 cm, which was the maximum possible depth allowed by the size of the test bin and the chamber. 相似文献
997.
Study on the uncertainty of the available time under ship fire based on Monte Carlo sampling method 总被引:1,自引:0,他引:1
Available safety egress time under ship fire(SFAT) is critical to ship fire safety assessment,design and emergency rescue.Although it is available to determine SFAT by using fire models such as the two-zone fire model CFAST and the field model FDS,none of these models can address the uncertainties involved in the input parameters.To solve this problem,current study presents a framework of uncertainty analysis for SFAT.Firstly,a deterministic model estimating SFAT is built.The uncertainties of the input parameters are regarded as random variables with the given probability distribution functions.Subsequently,the deterministic SFAT model is employed to couple with a Monte Carlo sampling method to investigate the uncertainties of the SFAT.The Spearman’s rank-order correlation coefficient(SRCC) is used to examine the sensitivity of each input uncertainty parameter on SFAT.To illustrate the proposed approach in detail,a case study is performed.Based on the proposed approach,probability density function and cumulative density function of SFAT are obtained.Furthermore,sensitivity analysis with regard to SFAT is also conducted.The results give a high-negative correlation of SFAT and the fire growth coefficient whereas the effect of other parameters is so weak that they can be neglected. 相似文献
998.
内蒙古巴彦查干湖白云石的成因及其环境意义 总被引:2,自引:0,他引:2
对内蒙古南部巴彦查干湖12400cal.aB.P.以来的沉积物进行了X-衍射、扫描电镜、碳酸盐含量和自生碳酸盐氧同位素组成的研究.结果显示,沉积物中碳酸盐含量较高,6000cal. aB.P.以前为方解石,之后白云石开始出现,4800cal.aB.P.以来代替方解石成为主要的碳酸盐矿物.方解石的形态为细长的结晶棱柱体和薄片状,白云石颗粒的形态均为小球粒状,这些形态特征表明方解石和白云石是快速沉淀形成的.白云石的形态和大小与澳大利亚Coorong等地区微生物成因的白云石非常相似,表明巴彦查干湖白云石的形成可能与微生物活动有关.白云石在6000cal.aB.P.的出现是湖水咸化的直接证据,表明气候变干,这一结果与碳酸盐氧同位素和孢粉记录一致. 相似文献
999.
1000.
以数个工程实例介绍了土条状坑壁常用的开挖支护方式及其适用条件,归纳总结了土条状坑壁支护中常见工程事故,提出了相应的解决处理方法,并指出其根本原因在于相邻基坑坑槽回填土的高含水性及欠固结性。可作为相似工程的借鉴经验。 相似文献