室外风场对庭院建筑热压通风的影响     

陈淑爱  钟珂  亢燕铭  胡开兵 《亚热带资源与环境学报》2009,4(3):31-36

针对具有一定内热源的庭院建筑,采用计算流体力学（CFD）方法,分析了热压自然通风量与庭院内热源和室外风向、风速的关系．结果表明房间的通风量随室外风速、风向的变化而变化,且热压对通风的相对影响作用随室外风速的增大而减弱．在对庭院式建筑进行自然通风系统设计时,这一结论可作为理论设计依据之一．  相似文献   

A new methodology for the extension of the impact of data assimilation on ocean wave prediction   总被引：1，自引：1，他引：0  

George Galanis  George Emmanouil  Peter C. Chu  George Kallos 《Ocean Dynamics》2009,59(3):523-535

It is a common fact that the majority of today's wave assimilation platforms have a limited, in time, ability of affecting the final wave prediction, especially that of long-period forecasting systems. This is mainly due to the fact that after “closing” the assimilation window, i.e., the time that the available observations are assimilated into the wave model, the latter continues to run without any external information. Therefore, if a systematic divergence from the observations occurs, only a limited portion of the forecasting period will be improved. A way of dealing with this drawback is proposed in this study: A combination of two different statistical tools—Kolmogorov–Zurbenko and Kalman filters—is employed so as to eliminate any systematic error of (a first run of) the wave model results. Then, the obtained forecasts are used as artificial observations that can be assimilated to a follow-up model simulation inside the forecasting period. The method was successfully applied to an open sea area (Pacific Ocean) for significant wave height forecasts using the wave model WAM and six different buoys as observational stations. The results were encouraging and led to the extension of the assimilation impact to the entire forecasting period as well as to a significant reduction of the forecast bias.  相似文献   

Responses of polar mesospheric cloud brightness to stratospheric gravity waves at the South Pole and Rothera,Antarctica     

Xinzhao Chu  Chihoko Yamashita  Patrick J. Espy  Graeme J. Nott  Eric J. Jensen  Han-Li Liu  Wentao Huang  Jeffrey P. Thayer 《Journal of Atmospheric and Solar》2009,71(3-4):434-445

We present the first observational proof that polar mesospheric cloud (PMC) brightness responds to stratospheric gravity waves (GWs) differently at different latitudes by analyzing the Fe Boltzmann lidar data collected from the South Pole and Rothera (67.5°S, 68.0°W), Antarctica. Stratospheric GW strength is characterized by the root-mean-square (RMS) relative density perturbation in the 30–45 km region and PMC brightness is represented by the total backscatter coefficient (TBC) in austral summer from November to February. The linear correlation coefficient (LCC) between GW strength and PMC brightness is found to be +0.09 with a 42% confidence level at the South Pole and ?0.49 with a 98% confidence level at Rothera. If a PMC case potentially affected by a space shuttle exhaust plume is removed from the Rothera dataset, the negative correlation coefficient and confidence level increase to ?0.61 and 99%, respectively. The Rothera negative correlation increases when shorter-period waves are included while no change is observed in the South Pole correlation. Therefore, observations show statistically that Rothera PMC brightness is negatively correlated with the stratospheric GW strength but no significant correlation exists at the South Pole. A positive correlation of +0.74 with a confidence level of 99.98% is found within a distinct subset of the South Pole data but the rest of the dataset exhibits a random distribution, possibly indicating different populations of ice particles at the South Pole. Our data show that these two locations have similar GW strength and spectrum in the 30–45 km region during summer. The different responses of PMC brightness to GW perturbations are likely caused by the latitudinal differences in background temperatures in the ice crystal growth region between the PMC altitude and the mesopause. At Rothera, where temperatures in this region are relatively warm and supersaturations are not as large, GW-induced temperature perturbations can drive subsaturation in the warm phase. Thus, GWs can destroy growing ice crystals or limit their growth, leading to negative correlation at Rothera. Because the South Pole temperatures in the mesopause region are much colder, GW-perturbed temperature may never be above the frost point and have less of an impact on crystal growth and PMC brightness. The observed phenomena and proposed mechanisms above need to be understood and verified through future modeling of GW effects on PMC microphysics and ray modeling of GW propagation over the South Pole and Rothera.  相似文献   

汶川余震序列的加卸载响应比分析     

张浪平  尹祥础  庄建仓  张晓涛  袁帅  梁乃刚 《地震》2009,29(1):60-67

该文首先将汶川余震序列分成西南、 东北两段, 用加卸载响应比方法分别进行分析, 结果表明震后两段的响应比值都比较低, 明显小于1, 这可判断汶川地震属于主余震型地震; 且地震序列中的强余震(M≥5.0)发生前加卸载响应比值出现明显异常, 大都是加卸载响应比出现峰值, 之后发生强余震。 考虑到主震后余震的时空丛集现象, 结合ETAS模型对原有的加卸载响应比计算式进行改造, 并分析了主震之后15天的改造后响应比值, 发现改造后的响应比在一定程度上消除了丛集的影响, 并展示了对紧随主震发生的强余震的预测能力。  相似文献   

复杂地形下黄河流域月平均气温分布式模拟   总被引：7，自引：0，他引：7  

帅燕华  张水昌  苏爱国  王汇彤  蔡报元  王慧 《中国科学D辑》2009,39(6):774-786

通过对常规气象站月平均气温资料的分析,发现在影响气温的众多因素中,海拔高度、太阳总辐射、地表长波有效辐射对气温具有显著影响．建立了月平均气温的物理经验统计模型,结合复杂地形下太阳总辐射分布式模拟结果,提出了依托常规地面气象观测资料实现复杂地形下月平均气温分布式模拟的方法,生成了黄河流域1km×lkm分辨率月平均气温、月平均最高气温、月平均最低气温的空间分布图．分析表明,模拟结果能较好地反映气温的宏观分布趋势和局地分布特征．交叉验证结果表明,模型具有很好的稳定性,各月平均气温、月平均最高气温、月平均最低气温的模拟误差平均为0．19～0．35℃;加密站验证和个例年验证表明,模型具有良好的空间维和时间维模拟能力．提出的月平均气温分布式模型立足于常规地面气象观测资料,不依赖于山地野外考察资料,可以方便地在广大地区推广应用．  相似文献   

基于三维构造张量的位场边界识别滤波器   总被引：3，自引：3，他引：0       下载免费PDF全文

周帅  黄大年  焦健 《地球物理学报》2016,59(10):3847-3858

地质体构造边界位置的确定是位场数据解释中的一项重要工作,现有很多基于位场梯度张量数据的边界检测滤波器,但存在识别边界位置模糊且无法均衡深浅地质体异常的缺点.本文定义了位场数据的三维构造张量,并提出基于位场构造张量的边界滤波器.为了同时显示不同振幅异常的边界位置,对新定义的滤波器进行归一化处理.在高阶均衡滤波器的计算中需要计算位场的垂向高阶导数,本文引入一种计算的稳定算法,基于拉普拉斯方程利用位场水平导数求解垂向导数,可减小垂向导数计算中产生的误差.将定义的滤波器应用到合成的重磁数据中证明了新方法相比传统的滤波器能更加清晰、准确地圈定边界位置,而且针对同时含有正负异常的地质情况,可避免产生额外的错误边界.最后将新的滤波器应用到实测的重磁数据的解释中,结果显示基于构造张量的滤波器可更准确清晰地划分出断裂的边界位置,发现更多的构造细节.  相似文献   

2014 年2 月12 日新疆于田MS 7. 3地震震害调查分析     

谭明  孙静  李帅  陈建波  吴传勇  姚远  常想徳  王琼  伊力亚尔·阿不力孜 《中国地震》2014,30(2):233-242

2014 年2 月12 日新疆于田县发生MS7. 3 地震,发震构造初步判断为阿尔金断裂带。推测极震区烈度为Ⅸ度,位于无人区;Ⅵ、Ⅶ度区为现场调查确定,共216 个烈度调查点。地震造成新疆和田地区和巴音郭楞蒙古自治州7 个县(市)的39 个乡、镇(场)的房屋、市政和交通设施、农牧业基础设施等受到不同程度的破坏。本次地震较2008 年3 月21 日于田MS7. 3 地震更靠近盆地,震害受场地条件影响明显,受灾范围更大。  相似文献   

Elevated Atmospheric CO2 Enhances Copper Uptake in Crops and Pasture Species Grown in Copper‐Contaminated Soils in a Micro‐Plot Study          下载免费PDF全文

Shuai Tian  Yan Jia  Yongzhen Ding  Ruigang Wang  Zhengguo Song  Junkang Guo  Li Zhou 《洁净——土壤、空气、水》2014,42(3):347-354

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Seasonal Water Quality Upstream of Dahuofang Reservoir,China – the Effects of Land Use Type at Various Spatial Scales          下载免费PDF全文

Yin Ye  Xingyuan He  Wei Chen  Jing Yao  Shuai Yu  Lian Jia 《洁净——土壤、空气、水》2014,42(10):1423-1432

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矿柱安全留设尺寸的宽度折减法与应用     

张涛  张帅  张百胜 《岩土力学》2014,35(7):2041-2046

从岩石强度理论出发,提出房柱式开采中矿柱安全留设尺寸的宽度折减法思想,通过不断折减矿柱宽度,研究矿柱由稳定状态向临界失稳状态演化过程,从而得到矿柱的临界宽度,引入矿柱安全系数,获得矿柱安全留设尺寸。采用宽度折减法对磨坊矿3#井房柱法开采矿柱安全留设尺寸进行研究,获得不同矿房跨度下矿柱的安全留设宽度。将宽度折减法得到的安全矿柱宽度与Lunder经验公式比较,研究发现,宽度折减法得到的安全矿柱宽度和Lunder经验公式的计算结果较为吻合且偏安全。结合磨坊矿3#井的开采条件和矿柱宽度折减法分析结果,确定矿房基本参数为：矿房跨度为13 m左右,矿柱宽度为5.0～5.5 m。通过对磨坊矿3#井采空区上覆岩层移动规律的监测,发现岩层相对稳定,地表沉降量控制在120～150 mm之间,用宽度折减法分析得到的矿房基本参数是合理的。  相似文献