Exploring the potential of artificial intelligence techniques in prediction of the removal efficiency of vortex tube silt ejector

A vortex tube silt ejector is a curative hydraulic structure used to remove sediment deposits from canals and is recognized as one of the most efficient substitutes for physically removing canal sediment. The spatially varied flow in the channel and the rotational flow behavior in the tube make the silt removal process complex. It is even harder to accurately predict the silt removal efficiency by traditional models accurately. However, artificial intelligence(AI) and machine learning approaches...     

2007-2008年武汉市空气质量预报和检验

通过开展武汉市空气质量预报研究,研讨武汉市空气质量状况。结果表明：2007-2008年武汉市空气质量优良的出现频率为77.6％,且未出现超过轻度污染的情况,其中夏季空气质量明显好于其他季节。经验证,采用逐步线性回归法建立的预报模型对武汉市空气质量具有一定的预报能力,级别预报准确率达78.1％。统计各级预报准确率发现,此方法较适用于空气质量为Ⅱ级的情况,提出在使用时应结合天气预报和前一日空气质量监测实况对预报结果进行修正。     

1961—2006年云南可利用降水量演变特征

利用云南122个测站1961—2006年逐月降水量、气温观测资料,依据高桥浩一郎的陆面实际蒸散发经验公式,计算了云南可利用降水量,分析了全球气候变暖背景下云南可利用降水量的变化特征,获得了一些有意义的结果:1)近50年来云南可利用降水量在春季增加,而其余季节减少,特别是夏季可利用降水量明显减少,导致云南年可利用降水量明显减少。2)云南可利用降水量除冬季年代际变化不明显,年际变化明显外,其余季节及年可利用降水量都存在明显的年代际及年际变化。3)从区域趋势变化看,云南大部可利用降水量在冬、春季以增加为主;夏季以减少为主;秋季东部减少,西部增加;全年可利用降水量东部、南部以减少为主,其余地区以增加为主。4)年可利用降水量在全球气候偏暖年以偏少为主,而在偏冷年则以偏多为主。     

太湖梅梁湾藻类及相关环境因子逐步回归统计和蓝藻水华的初步预测

以太湖梅梁湾1992－1999年的连续监测资料为基础,运用多元逐步回归统计方法,选择水温等15项环境理化因素与藻类叶绿素a、藻类总生物量和微囊藻生物量等3项生物因素进行逐步回归分析,找出与生物因素显著相关的环境因子,建立多元逐步回归方程,预测梅梁湾藻类生物量的变化情况,初步进行了梅梁湾蓝藻水华的预测预报,结果显示,水温和总磷为梅梁湾藻类总生物量的显著相关因子,水温、硝态氮和总氮为微囊藻一物量的显著相关因子。     

关于基线值拟合问题的讨论

基线值是沟通相对记录与绝对观测的桥梁,是相对记录仪器的工作状态与绝对观测值的准确程度的综合反应,它在地磁台站工作中具有举足轻重的地位和作用。如何准确地、定量地评定基线值的质量,是一个对台站工作有指导意义的重要问题。本文指出多元线性回归方法用于基线值拟合和质量评定的物理机制清楚,计算结果有明确的物理意义。对多项式拟合方法及基线值的温度系数和误差统计的某些观点也进行了讨论。     

金河地震台水氡动态特征及应震效能评份

本文在对金河地震台泉点多年的水氡和辅助观测资料进行清理的基础上,就泉点所处构造部位、水文地质条件、观测环境、干扰因素、影响机理进行了分析。对水氡动态特征进行了探讨。最后,根据该台观测资料的实际情况,选用多元逐步回归分析方法建立最优回归方程式,排除干扰影响。并就排除干扰影响后的水氡资料的应震效能进行评价。     

Pre-summer Persistent Heavy Rain over Southern China and Its Relationship with Intra-seasonal Oscillation of Tropical Atmosphere

Based on daily precipitation data supplied by the Chinese meteorological administration, hourly reanalysis datasets provided by the ECMWF and daily outgoing long wave radiation supplied by the NOAA, the evolution regularity of continuous heavy precipitation over Southern China(SC) from April to June in 1979-2020 was systematically analyzed. The interaction between specific humidity and circulation field at the background-scale, the intra-seasonal-scale and the synoptic-scale, and its influence o...     

A simplified method of constructing fragility curves for highway bridges

Fragility curves are found to be useful tools for predicting the extent of probable damage. They show the probability of highway structure damage as a function of strong motion parameters, and they allow the estimation of a level of damage probability for a known ground motion index. In this study, an analytical approach was adopted to develop the fragility curves for highway bridges based on numerical simulation. Four typical RC bridge piers and two RC bridge structures were considered, of which one was a non‐isolated system and the other was an isolated system, and they were designed according to the seismic design code in Japan. From a total of 250 strong motion records, selected from Japan, the United States, and Taiwan, non‐linear time history analyses were performed, and the damage indices for the bridge structures were obtained. Using the damage indices and ground motion parameters, fragility curves for the four bridge piers and the two bridge structures were constructed assuming a lognormal distribution. It was found that there was a significant effect on the fragility curves due to the variation of structural parameters. The relationship between the fragility curve parameters and the over‐strength ratio of the structures was also obtained by performing a linear regression analysis. It was observed that the fragility curve parameters showed a strong correlation with the over‐strength ratio of the structures. Based on the observed correlation between the fragility curve parameters and the over‐strength ratio of the structures, a simplified method was developed to construct the fragility curves for highway bridges using 30 non‐isolated bridge models. The simplified method may be a very useful tool to construct the fragility curves for non‐isolated highway bridges in Japan, which fall within the same group and have similar characteristics. Copyright © 2003 John Wiley & Sons, Ltd.     

利用广西邕宁、灵山地应力资料预报周边地区中强震发震时间的初步探讨

采用回归分析及周期分析法消除了广西邕宁和灵山地应力测值因观测室室温、湿度等因素所引起的年变化;又对地应力资料做了去除长趋势变化和用卡尔曼滤波平滑地应力曲线的处理后,可以看出邕宁、灵山地应力对于200km范围内的Ms4．5—4．7级地震、300km范围内的Ms4．8—5．4级地震以及400km范围内的M5≥5．5级地震具有一定的预报能力。在中强震发生之前的2年内,邕宁、灵山地应力某分向会出现2次以上的超1．5倍均方差异常,且在2次异常所跨越的时段内至少另有1个分向也会显示有1次以上的异常,当第2次异常结束后的8个月内,在上述规定的距离范围内发生中强震的可能性很大。     

The Use of Radar and Gauge Measurements to Estimate Areal Precipitation for Several Czech River Basins

Two methods estimating areal precipitation for selected river basins in the Czech Republic are compared. The methods use radar precipitation (the radar-derived precipitation estimate based on column maximum reflectivity) and data from 81 on-line rain gauges routinely provided by the Czech Hydrometeorological Institute. Data from a dense network of climatological rain gauges (the average inter-station distance is approximately 8 km), the measurements of which are not available in real time, are utilized for the verification. The mean areal precipitation, which is used as the ground truth, is obtained by the weighted interpolation of the dense rain gauge network. The accuracy of the methods is evaluated by the root-mean-square-error.The first, pixel-related method merges radar precipitation with rain gauge data to obtain adjusted pixel values. The adjusting procedure combines radar and gauge values in one variable that is interpolated into all radar pixels. The adjusted pixel precipitation is calculated from radar precipitation and from the value of the combined variable. The areal estimates are determined by adding the corresponding pixel values. The second method applies a linear regression model to describe the relationship between the areal precipitation (dependent variable) and its estimates, which are determined from (i) non-adjusted radar precipitation and (ii) on-line rain gauge measurements interpolated into pixels. Classical linear regression, ridge regression and robust regression models are tested.Both the methods decrease the average areal error in comparison with the reference method, which uses the on-line rain gauge data only. The decrease is about 10% and 15% for the pixel-related and regression methods, respectively. When the estimates of the pixel-related method are included as predictors into the regression method then the improvement of accuracy is almost 25%.