基于TS模型的结构振动模糊控制方法     

李淑玉  刘栋栋 《世界地震工程》2005,21(1):61-65

将TS模糊控制模型用于结构振动控制中,提出了一种新型的模糊控制器。利用传统LQR控制算法确定TS模糊控制器的参数,提出一种新的形成模糊控制规则的方法,克服了TS模糊控制器参数较多,规则难以确定的缺点;并结合一座三层钢框架模型,进行仿真分析,验证了提出的方法的有效性。  相似文献   

智能网格SCMOC及多模式降水预报对比          下载免费PDF全文

潘留杰  张宏芳  刘静  刘嘉慧敏  梁绵  祁春娟  戴昌明  李培荣 《大气科学学报》2023,46(2):217-229

以三源融合网格实况降水分析资料CMPAS为参照,基于二分法经典检验、预报评分综合图和面向对象MODE检验等方法,对比分析2021年智能网格预报SCMOC以及ECMWF全球、CMA-Meso中尺度模式在秦岭及周边地区的降水预报表现,主要结论如下：1)ECMWF能够很好地刻画日平均降水量、日降水量标准差以及地形影响下降水量、降水频次的空间分布特征,但对于0.1 mm以上量级的降水预报频次远高于观测,暴雨预报频次低于观测,SCMOC、CMA-Meso日降水量大于等于0.1 mm的降水频次和暴雨频次预报更好;SCMOC不足在于降水的空间精细分布特征描述能力相对较弱。2)ECMWF预报的大于等于0.1 mm降水频次日峰值出现时间整体较观测偏早3 h左右,CMA-Meso、SCMOC与观测总体吻合较好。3)三种产品24 h降水量大于等于0.1 mm的TS(Threat Score)评分数值上基本一致,但降水预报表现的特征显著不同,SCMOC成功率高、命中率低,漏报多、空报少,ECMWF、CMA-Meso则相反;24 h、3 h大雨以上量级降水SCMOC的TS评分、成功率、命中率一致优于其他两种产品...  相似文献   

MCTSI联合D-D评估急性胰腺炎患者临床预后的可行性分析          下载免费PDF全文

方芳  谭伟  胡少平 《CT理论与应用研究》2019,28(1):139-146

目的:评估MCTSI评分联合D-二聚体检测值与急性胰腺炎患者临床预后的相关性。方法:收集我院2016年8月至2018年1月间收治并确诊的急性胰腺炎患者150例,记录入院后首日血浆D-二聚体检测值,并于第5～7日行CT增强扫描检查,根据MCTSI标准进行评分,将MCTSI评分和血浆D-二聚体检测值经过Logistic回归方程得出联合检测值,并将MCTSI评分、D-二聚体检测值、联合检测值进行ROC曲线分析。结果:轻、中、重度急性胰腺炎患者血浆D-二聚体检测值及预后存在有明显差异(P <0.001),重度患者D-二聚体检测值显著高于轻、中度患者(P <0.001)。MCTSI评分和血浆D-二聚体检测值经过Logistic回归方程得出联合检测值对于患者器官功能衰竭预测的效能优于单独使用MCTSI评分及血浆D-二聚体检测值预测的效能,且其与住院天数的相关系数也最高。结论:针对急性胰腺炎患者,参照MCTSI以及D-二聚体检测值进行联合评估,可了解患者预后情况,具备较高的临床参考价值。  相似文献   

Comparison of ground-based and UAV a-UHF artificial tracer mobility monitoring methods on a braided river     

M. Cassel  H. Piégay  G. Fantino  J. Lejot  L. Bultingaire  K. Michel  F. Perret 《地球表面变化过程与地形》2020,45(5):1123-1140

Radio frequency identification (RFID) technologies, which allow wireless detection of individual buried or immersed tracers, represent a step forward in sediment tracking, especially passive integrated transponders (PIT tags) that have been widely used. Despite their widespread adoption in the scientific community, they typically have low efficiency when deployed in river systems with active bedload transport or deep wet channels, attributed to their technical specifications. A recent evaluation of active ultra-high frequency transponders (a-UHF tags) assessed their larger detection range and provided a methodology for their geopositioning. In this study, we test five different survey methods (one including an unmanned aerial vehicle [UAV]) in a sediment tracking study, and compare them in terms of recovery rate, field effort, geopositioning error, and efficiency. We then tested the method on a larger reach following a Q₅ flood and performed cross-comparisons between active and passive RFIDs. The results confirmed that the a-UHF RFID technology allowed rapid (1.5 h ha⁻¹) survey of a large area (<34 ha) of emerged bars and shallow water channels with recovery of a high percentage of tracers (72%) that had travelled large distances (mean ≈ 1000 m; max ≈ 3400 m). Moreover, the tracers were identified with low geopositioning error (mean ≈ 7.1 m, ≤1% of their travel distance). We also showed that a UAV-based survey was fast (0.38 h ha⁻¹), efficient (recovery rate = 84%), and low error (mean ≈ 4.2 m). Thus, a-UHF RFID technology permits the development of a variety of survey methods, depending on the study objectives and the human and financial resources available. This allows field efforts to be optimized by determining an appropriate balance between the high equipment cost of a-UHF tracers and the resulting reduced survey costs. © 2019 John Wiley & Sons, Ltd.  相似文献   

地统计学用于空间不确定性的描述(英文)     

张景雄  张金平  姚娜 《地球空间信息科学学报》2009,12(1):7-12

Most geospatial phenomena can be interpreted probabilistically because we are ignorant of the biophysical processes and mechanisms that have jointly created and observed events. This philosophy is important because we are certain about the phenomenon under study at sampled locations, except for measurement errors, but, in between the sampled, we become uncertain about how the phenomenon behaves. Geostatistical uncertainty characterization is to generate random numbers in such a way that they simulate the outcomes of the random processes that created the existing sample data. This set of existing sample is viewed as a partially sampled realization of that random function model. The random function’s spatial variability is described by a variogram or covariance model. The realized surfaces need to honour sample data at their locations, and reflect the spatial structure quantified by the variogram models. They should each reproduce the sample histogram representative of the whole sampling area. This paper will review the fundamentals in stochastic simulation by covering univariate and indicator techniques in the hope that their applications in geospatial information science will be wide-spread and fruitful. Supported by the National 973 Program of China (No. 2006CB701302).  相似文献   

干旱对河西走廊植被净初级生产力的影响     

李传华  殷欢欢  朱同斌  周敏  王玉涛  孙皓  曹红娟  韩海燕 《中国沙漠》2021,41(1):145-155

干旱对生态系统碳循环具有重要影响,随着气候变暖,全球干旱事件频率不断上升,研究干旱对植被净初级生产力的影响具有重要意义.提高植被净初级生产力(NPP)的时间分辨率是认识干旱对其影响机制的重要途径.基于5天NDVI遥感数据,以河西走廊为研究区,利用CASA模型估算2010-2015年5天步长尺度的NPP,将5天降水为零定...  相似文献   

Case studies of seasonal rainfall forecasts for Hong Kong and its vicinity using a regional climate model     

David Tai-Wai Hui  Karen Kit-Ying Shum  Ji Chen  Shyh-Chin Chen  Jack Ritchie  John O. Roads 《Natural Hazards》2007,42(1):193-207

Seasonal climate forecasts are one of the most promising tools for providing early warnings for natural hazards such as floods and droughts. Using two case studies, this paper documents the skill of a regional climate model in the seasonal forecasting of below normal rainfall in southern China during the rainy seasons of July–August–September 2003 and April–May–June 2004. The regional model is based on the Regional Spectral Model of the National Centers for Environmental Prediction of the United States. It is the first time that the model has been applied to a region dominated by the East Asian Monsoon. The article shows that the regional climate model, when being forced by reasonably good forecasts from a global model, can generate useful seasonal rainfall forecasts for the region, where it is dominated by the East Asia monsoon. The spatial details of the dry conditions obtained from the regional climate model forecast are also found to be comparable with the observed distribution.  相似文献   

铅同位素在扬子地台西缘铅锌矿床找矿靶标建立中的初步应用     

曾令刚  顾雪祥  王小春  李仕荣 《新疆地质》2005,23(4):378-385

收集了扬子地台西缘铅锌矿带岩、矿石铅同位素组成数据257组，通过分析认为，该矿带铅同位素组成具有变化大（尤其是大型矿床），线性排列显著，数据分布相对集中，接近正态分布等特征．根据其特征，采用常向阳等提出的建立铅同位素化探找矿靶标的方法，初步建立了该矿带的铅锌矿床铅同位素找矿远景区靶标，并根据靶标划分出5类找矿靶区，可作为该矿带找矿远景区评价的一种依据．  相似文献   

PERSISTENCES IN THE δ~(13)C AND δ~(18)O FROM TS95, A LAKE CORE AT THE SOUTH FRANK OF WEST KUNLUN MOUNTAIN     

Zhou Houyun  Zhu Zhaoyu  Wen Qizhong  Li Bingyuan  Li Shijie  He Yixian 《地学前缘》2000,(Z1)

PERSISTENCES IN THE δ~(13)C AND δ~(18)O FROM TS95, A LAKE CORE AT THE SOUTH FRANK OF WEST KUNLUN MOUNTAIN  相似文献   

GRAPES中尺度模式中不同积云参数化方案预报性能对比研究   总被引：3，自引：2，他引：1  

郭云云  邓莲堂  范广洲  李泽椿 《气象》2015,41(8):932-941

利用我国新一代中尺度数值模式GRAPES_Meso,采用KFeta和BMJ两种积云对流参数化方案,对我国2009年冬季(1月)和夏季(6—8月)天气进行批量回报试验。回报试验结果表明：在冬季,两种方案对GRAPES_Meso模式的预报性能影响差异较小。在夏季,两种方案对模式回报效果的影响表现明显。在低层BMJ方案对形势场的回报性能略优于KFeta方案,中层则是KFeta方案明显优于BMJ方案,而在高层KFeta方案略优于BMJ方案。TS评分检验表明KFeta方案对降水的预报总体上优于BMJ方案,特别是中雨到暴雨量级在华南地区KFeta方案有明显的优势。两个方案预报积云降水平均贡献率的空间分布差异主要表现在低纬度洋面上,BMJ方案的贡献率比KFeta方案大。两个方案积云降水贡献率的概率分布形态在小雨量级上都呈陡峭的“U”型分布。KFeta方案随着降水量级的增大逐渐向大贡献率偏移,特大暴雨量级时基本上是积云降水的贡献;而BMJ参数化方案则是随着降水量级的增大逐渐向小贡献率偏移,特大暴雨量级时基本上是格点降水的贡献。  相似文献