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A method to predict rockburst using temporal trend test and its application
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作者 Yarong Xue Zhenlei Li +5 位作者 Dazhao Song Xueqiu He Honglei Wang Chao Zhou Jianqiang Chen Aleksei Sobolev 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第3期909-923,共15页
Rockbursts have become a significant hazard in underground mining,underscoring the need for a robust early warning model to ensure safety management.This study presents a novel approach for rockburst prediction,integr... Rockbursts have become a significant hazard in underground mining,underscoring the need for a robust early warning model to ensure safety management.This study presents a novel approach for rockburst prediction,integrating the Mann-Kendall trend test(MKT)and multi-indices fusion to enable real-time and quantitative assessment of rockburst hazards.The methodology employed in this study involves the development of a comprehensive precursory index library for rockbursts.The MKT is then applied to analyze the real-time trend of each index,with adherence to rockburst characterization laws serving as the warning criterion.By employing a confusion matrix,the warning effectiveness of each index is assessed,enabling index preference determination.Ultimately,the integrated rockburst hazard index Q is derived through data fusion.The results demonstrate that the proposed model achieves a warning effectiveness of 0.563 for Q,surpassing the performance of any individual index.Moreover,the model’s adaptability and scalability are enhanced through periodic updates driven by actual field monitoring data,making it suitable for complex underground working environments.By providing an efficient and accurate basis for decision-making,the proposed model holds great potential for the prevention and control of rockbursts.It offers a valuable tool for enhancing safety measures in underground mining operations. 展开更多
关键词 ROCKBURST MICROSEISMICITY Early warning Mann-Kendall trend test Confusion matrix Multi-indices fusion
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Detecting Global Vegetation Changes Using Mann-Kendal(MK) Trend Test for 1982–2015 Time Period 被引量:12
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作者 GUO Meng LI Jing +2 位作者 HE Hongshi XU Jiawei JIN Yinghua 《Chinese Geographical Science》 SCIE CSCD 2018年第6期907-919,共13页
Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understan... Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understand the trends of vegetation cover, this research examined the spatial-temporal trends of global vegetation by employing the normalized difference vegetation index(NDVI) from the Advanced Very High Resolution Radiometer(AVHRR) Global Inventory Modeling and Mapping Studies(GIMMS) time series(1982–2015). Ten samples were selected to test the temporal trend of NDVI, and the results show that in arid and semi-arid regions, NDVI showed a deceasing trend, while it showed a growing trend in other regions. Mann-Kendal(MK) trend test results indicate that 83.37% of NDVI pixels exhibited positive trends and that only 16.63% showed negative trends(P < 0.05) during the period from 1982 to 2015. The increasing NDVI trends primarily occurred in tree-covered regions because of forest growth and re-growth and also because of vegetation succession after a forest disturbance. The increasing trend of the NDVI in cropland regions was primarily because of the increasing cropland area and the improvement in planting techniques. This research describes the spatial vegetation trends at a global scale over the past 30+ years, especially for different land cover types. 展开更多
关键词 vegetation trend NDVI3g.v1 Mann-Kendall (MK) trend test land cover types
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Provenance of Coloured Gemstones-Availability,Testing Methods,Future Trends 被引量:1
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作者 Lore Kiefert Klemens Link 《宝石和宝石学杂志》 CAS 2018年第S1期145-146,共2页
Gemstones have fascinated mankind forever,and people traveled far to find them.The Silk Road is one of the most traditional trade routes in the middle ages that was used to bring the precious stones to the European ma... Gemstones have fascinated mankind forever,and people traveled far to find them.The Silk Road is one of the most traditional trade routes in the middle ages that was used to bring the precious stones to the European market.Later,emeralds from Colombia were shipped via the ocean to the Old World. 展开更多
关键词 Provenance of Coloured Gemstones-Availability testing Methods Future trends
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Analysis of Daily Rainfall in São Carlos/SP, Brazil over 1979-2017 Using Laplace Trend Test
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作者 Rafael Grecco Sanches Bruno César Dos Santos +3 位作者 Rodrigo Sanches Miani Gustavo Zen de Figueiredo Neves Mauricio Sanches Duarte Silva Adriano Rogério Bruno Tech 《Journal of Geoscience and Environment Protection》 2020年第7期104-125,共22页
Rainfall expresses one of the most complex climate factors in Southeastern Brazil. Understanding the dynamics and temporal trends of rainfall represents a significant challenge due to regional and even global mechanis... Rainfall expresses one of the most complex climate factors in Southeastern Brazil. Understanding the dynamics and temporal trends of rainfall represents a significant challenge due to regional and even global mechanisms, such as FS (Frontal Systems) and the SACZ (South Atlantic Convergence Zone), and the interaction with the Atlantic and Pacific Oceans. The present study aimed at analyzing the pluviometric tendencies in S<span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">&#227</span>o Carlos/SP, in the countryside of S<span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">&#227</span>o Paulo State. Laplace trend test was used to comprehend the temporal evolution of daily rainfall in the region in the historical series 1979-2017, in seven pluviometric stations (climatological or surface stations). Significant fluctuations in interannual trends and between seasons were observed. However, it was noted that the beginning of the 1980s showed positive trends, whereas, as of the year 2000, most of the stations demonstrated negative trends, indicating a reduction in daily rainfall volume due to the great tropical climatic variability of Brazil. Emphasis should also be given to the regional and local effects, such as elevation and urbanization, respectively, which corroborate such differences among the analyzed stations. This methodology is of considerable value for the observation of pluviometric trends, and future studies can validate such a tool in climatological studies. 展开更多
关键词 Tropical Climatology Climate Variability Rainfall trends Statistical Tool Laplace trend test
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Numerical test and evaluating method of impact trend of rock-coal system
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作者 蒋金泉 程家国 +1 位作者 曲华 董建军 《Journal of Coal Science & Engineering(China)》 2008年第1期12-18,共7页
The impact trend of reck-coal system was studied by the method of accumulating and releasing of deformation energy and interaction of rock-coal system. The system model of roof-coal-floor was established. Based on the... The impact trend of reck-coal system was studied by the method of accumulating and releasing of deformation energy and interaction of rock-coal system. The system model of roof-coal-floor was established. Based on the RFPA software, rock fracture process analysis system, the numerical test of deformation, fracture and energy transmission of nonlinear and nonhomogeneous rock-coal system, and the numerical test and evaluating method of impact trend of reck-coal system were achieved. When the same coal seam was in different roof and floor conditions, the fracture process of reck-coal system can be classified as gradual, sudden and delayed fracture three kinds, and their impact trend can be classified as void, intense and medium correspondingly. The rock-coal system's impact trend is evaluated by the system impact index p and burst expanding forms. The criteria μ are μ〈1.0, 1.0≤μ〈l .5 and μ≥1.5 when the impact trend is void, intense or medium, which are tested and verified by the No.2 and No.4 coal seams in Sun- cun mine. 展开更多
关键词 impact trend rock-coal system numerical test impact energy index evaluating method
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Investigation into Recent Temperature and Rainfall Trends in Mali Using Mann-Kendall Trend Test: Case Study of Bamako
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作者 Alikalifa Sanogo Roland Songotu Kabange +3 位作者 Prince Appiah Owusu Bakary Issa Djire Racheal Fosu Donkoh Nasser Dia 《Journal of Geoscience and Environment Protection》 2023年第3期155-172,共18页
Rainfall and temperature variability analysis is important for researchers and policy formulators in making critical decisions on water availability and use in communities. The Western Sahel, which comprises Mali is c... Rainfall and temperature variability analysis is important for researchers and policy formulators in making critical decisions on water availability and use in communities. The Western Sahel, which comprises Mali is considered as one of the vulnerable regions to climate change, and also encountered the challenges of climatic shocks such as flood and drought. This research therefore sought to investigate climate change effects on hydrological events and trends in Sahelian rainfall intensity using Bamako (Mali) as a case study from 1991 to 2020, as limited data availability did not allow an extended period of study. Monthly observed data provided by MALI-METEO was used to validate daily rainfalls data from African Rainfall Climatology Version 2 (ARC2) satellite-based rainfall product on monthly basis. The validated model performance used Nash-Sutcliffe Efficiency (NSE) and Percent Bias (PBAIS) and gave results of 0.904 and 1.0506 respectively. Trends in annual maximum temperatures and rainfalls were analyzed using Mann-Kendall trend test. The result indicated that the trend in annual maximum rainfalls was decreasing, while annual total rainfall was increasing but not significant at 5% significance level. The rate of increase in annual total rainfalls was 0.475 mm/year according to the observed annual rainfall series and decreased to 0.68 mm/year in annual maximum. The analysis further found that annual maximum temperatures were increasing at the rate of 0.03°C/year at 5% significance level. To provide more accurate climate predictions, it is recommended that further studies on rainfall and temperature with data sets spanning 60 - 90 years be carried out. 展开更多
关键词 Sahel Countries BAMAKO Recent trends Mann-Kendall trend test Climate Change
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On the Different Ways to Handle the Trend of Disease Risk in Genetic Association Tests
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作者 Tapati Basak 《Open Journal of Statistics》 2022年第4期521-531,共11页
Genetic association studies usually apply the simple chi-square (χ<sup>2</sup>)-test for testing association between a single-nucleotide polymorphism (SNP) and a particular phenotype, assuming the genotyp... Genetic association studies usually apply the simple chi-square (χ<sup>2</sup>)-test for testing association between a single-nucleotide polymorphism (SNP) and a particular phenotype, assuming the genotypes and phenotypes are independent. So, the conventional χ<sup>2</sup>-test does not consider the increased risk of an individual carrying the increasing number of disease responsible allele (a particular genotype). But, the association tests should be performed with the consideration of this disease risk according to the mode of inheritance (additive, dominant, recessive). Practical demonstration of the two possible methods for considering such order or trends in contingency tables of genetic association studies using SNP genotype data is the purpose of this paper. One method is by pooling the genotypes, and the other is scoring the individual genotypes, based on the disease risk according to the inheritance pattern. The results show that the p-values obtained from both the methods are similar for the dominant and recessive models. The other important features of the methods were also extracted using the SNP genotype data for different inheritance patterns. 展开更多
关键词 Association CHI-SQUARE trend test SNP GENOTYPE
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基于M-K检验法的青海高原降水特征分析 被引量:1
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作者 侯永慧 张玉欣 +2 位作者 张博越 朱世珍 龚静 《青海科技》 2024年第2期131-139,共9页
利用青海省49个气象站1961-2018年降水资料,将青海省分为3个区域,采用单变量和多变量Mann-Kendall(M-K)检验法,分析了青海省降水时空变化特征。结果表明:1961-2018年,青海省年平均降水量总体呈上升趋势;年平均降水量、年平均降水日数、... 利用青海省49个气象站1961-2018年降水资料,将青海省分为3个区域,采用单变量和多变量Mann-Kendall(M-K)检验法,分析了青海省降水时空变化特征。结果表明:1961-2018年,青海省年平均降水量总体呈上升趋势;年平均降水量、年平均降水日数、年最大降水量的空间分布基本保持一致,呈由东南向西北递减趋势,三者最高在黄河源地区、祁连山东段、青海省东部地区和三江源东部地区,其次为三江源中西部地区,最低值在柴达木盆地。青海省降水量总体呈上升趋势主要是由Ⅰ区(柴达木盆地和祁连山区)和Ⅲ区(三江源地区)降水量显著上升引起的,而Ⅱ区(青海省东部地区)降水量变化不显著。在整体趋势分析方面,单变量检验只能分析单个变量的变化趋势,多变量检验能综合分析联合变量的变化趋势,单变量和多变量M-K趋势分析方法结合应用,能同时考虑整体序列中的每个成分的趋势变化,从而得出更加可靠和准确的结论,分析结果对进一步了解青海高原降水特征,合理开发和利用降水资源具有重要的参考价值。 展开更多
关键词 青海省 降水 多变量趋势分析 m-k检验
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Communicative Testing:A Trend of Modern EFL Testing
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作者 周大军 明瑞龙 任苗苗 《海外英语》 2018年第9期247-248,共2页
Communicative testing, with its purpose of measuring communicative competence, has brought changes to the current EFL tests in content and format and produced a widespread and profound influence on modern language tes... Communicative testing, with its purpose of measuring communicative competence, has brought changes to the current EFL tests in content and format and produced a widespread and profound influence on modern language testing models in the two decades. This paper gives a brief introduction to the development of communicative testing, and presents the trend of modern EFL testing in the aspects of oral test, proportion of subjective and objective items, content, context, incorporation of skills as well as criteria of assessment, which is the result of enlightenment of communicative testing theories. 展开更多
关键词 communicative competence EFL testing trend
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The development and implementation of pathological parameters and molecular testing impact prognosis of colorectal adenocarcinoma 被引量:1
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作者 Midie Xu Yaqi Li +15 位作者 Yingxue Liu Jinjia Chang Changming Zhou Weiwei Weng Hui Sun Cong Tan Xin Wang Xu Wang Meng Zhang Shujuan Ni Lei Wang Yu Yang Xiaoyan Zhou Junjie Peng Dan Huang Weiqi Sheng 《Journal of the National Cancer Center》 2024年第1期74-85,共12页
Objective:This study aims to analyze how changes in pathological diagnosis practice and molecular detection technology have affected clinical outcomes for colorectal cancer(CRC)patients in Hehai University Shanghai Ca... Objective:This study aims to analyze how changes in pathological diagnosis practice and molecular detection technology have affected clinical outcomes for colorectal cancer(CRC)patients in Hehai University Shanghai Cancer Center(FUSCC).Methods:This retrospective cohort study analyzed 21,141 pathologically confirmed CRC cases diagnosed at FUSCC from 2008 to 2020.Patients were divided into five groups for different analytical purposes:(1)the before vs.since 2014 groups to analyze the influence of the changes in the classification criteria of pT3 and pT4 staging on the survival of patients;(2)the partial vs.total mesorectal excision(TME)groups to analyze whether evaluation of completeness of the mesorectum have impact on the survival of patients;(3)the tumor deposit(TD)(+)N0 vs.TD(+)N1c groups to analyze the influence of the changes in the pN staging on the survival of patients with positive TD and negative regional lymph node metastasis(LNM);(4)the before vs.since 2013 groups to analyze the influence of the changes in the testing process of deficient mismatch repair on the survival of patients;and(5)the groups with vs.without RAS/BRAF gene mutation testing to analyze the influence of these testing on the survival of patients.Patients’clinicopathological parameters,including age at diagnosis,sex,tumor size,location,differentiation,mucinous subtype,TD,lymphovascular invasion,perineural invasion,tumor depth,LNM and distant metastasis,and tumor-node-metastasis(TNM)stage,were compared between groups.Kaplan-Meier analysis with log rank method was performed for patients’overall survival(OS)and disease-free survival(DFS)analyses.Results:In pathological reports,there were three parameter changes that impacted patient outcomes.Firstly,changes in the pT staging criteria led to a shift of the ratio of patients with stage pT3 to stage pT4 from 1:110.9 to 1:0.26.In comparison to patients admitted before 2014(n=4,754),a significant difference in prognosis between pT3 and pT4 stages was observed since 2014(n=9,965).Secondly,we began to evaluate the completeness of the mesorectum since 2016.As a result,91.0%of patients with low rectal cancer underwent TME(n=4,111)surgery,and patients with TME had significantly better OS compared with partial mesorectal excision(PME,n=409).Thirdly,we began to stage TD(+)LNM(-)as N1c since 2017.The results showed that N1c(n=127)but not N0(n=39)can improve the prognosis of patients without LNM and distal metastasis.In molecular testing,there have been three and five iterations of updates regarding mismatch repair(MMR)/microsatellite instability(MSI)status and RAS/BRAF gene mutation detection,respectively.The standardization of MMR status testing has sharply decreased the proportion of deficient MMR(dMMR)patients(from 32.5%to 7.4%)since 2013.The prognosis of patients underwent MMR status testing since 2013(n=867)were significantly better than patients before 2013(n=1,313).In addition,detection of RAS/BRAF gene mutation status(n=5,041)resulted in better DFS but not OS,for patients with stage I-III disease(n=16,557).Conclusion:Over the past few decades,updates in elements in pathological reports,as well as the development of standardized tests for MMR/MSI status and RAS/BRAF gene mutations have significantly improved patient outcomes. 展开更多
关键词 Colorectal adenocarcinoma Pathological features Molecular testing trendS PROGNOSIS
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基于水质指数法和M-K检验的饮用水水源地水质演变趋势研究
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作者 姚嘉伟 李燕 +2 位作者 吕业佳 罗凡 陈宇华 《环境科学与管理》 CAS 2024年第4期43-48,共6页
饮用水水源地水质演变趋势研究对水源地的保护具有重要意义。以中国某城市6个市级水源地为研究对象,采用水质指数法进行水质评价,在此基础上结合Pettitt Mann Whitney变异点分析法、Mann-Kendall趋势检验法和线性回归法,深入分析了各水... 饮用水水源地水质演变趋势研究对水源地的保护具有重要意义。以中国某城市6个市级水源地为研究对象,采用水质指数法进行水质评价,在此基础上结合Pettitt Mann Whitney变异点分析法、Mann-Kendall趋势检验法和线性回归法,深入分析了各水源地水质突变时间及演变趋势,并结合该市近年来的管理政策分析了水质变化的原因。2020年-2022年各水源地水质现状整体较好,4个水源地水质评价结果为优良,其余为良好。变异点和演变趋势分析结果表明,各水源地均存在突变时间,水质指数突变时间主要集中在2021年2月-2022年4月,突变后2个水源地水质变差,其余水源地水质变好,仅1个水源地变异显著。该市水源地整体上2022年水质状况优于往年,主要得益于流域整体水环境质量改善和水源地特殊保护的加强。 展开更多
关键词 饮用水水源地 水质指数 Pettitt Mann Whitney变异点分析 Mann-Kendall趋势检验
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气候变化对土壤中硝氮污染物的迁移影响——以龙游县为例
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作者 刘欢 许悦 王乐婧 《浙江水利科技》 2025年第2期25-33,38,共10页
2021年12月,生态环境部等七部门联合发布《“十四五”土壤、地下水、农村生态环境保护规划》,浙江省根据该规划制定了至2025年,将受污染耕地安全利用率提高至95%左右的目标。据此,以浙江省衢州市龙游县为研究区域,根据该区1992—2022年... 2021年12月,生态环境部等七部门联合发布《“十四五”土壤、地下水、农村生态环境保护规划》,浙江省根据该规划制定了至2025年,将受污染耕地安全利用率提高至95%左右的目标。据此,以浙江省衢州市龙游县为研究区域,根据该区1992—2022年的历史气象数据与土样数据,建立模型并对土壤中硝氮浓度变化进行模拟。在得到日硝氮浓度变化数据的基础上,通过M-K趋势检验、Pettitt突变检验、皮尔逊相关性分析、多元回归分析的方法,对研究区域气候变化即气象因子对土壤中硝氮浓度迁移变化的影响进行分析。得到结论:①硝氮浓度随时间变化有明显周期性,且与降雨量的趋势变化更密切、与潜在蒸发量的趋势变化发展存在一定的时间差;②降雨量与硝氮浓度变化有更大的相关性,两者之间存在显著的影响关系;③降雨量显著正向影响硝氮浓度的值,潜在蒸发量负向影响硝氮浓度的值,且降雨量对硝氮浓度变化的贡献更大。土壤中硝氮浓度的变化呈现出一定的季节规律特征,并通过此规律,结合地区气候特征,对土壤中硝氮易累积时段作出预测并提前准备防治方法。 展开更多
关键词 HYDRUS-1D模型 m-k趋势检验 Pettitt突变检验 皮尔逊相关性分析 多元回归分析
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EMD及其扩展方法在水文学中的研究进展及应用综述
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作者 陈云飞 刘祖钰 +3 位作者 刘秀花 贺军奇 郑策 马延东 《灌溉排水学报》 2025年第2期101-112,共12页
受气候变化、生态演替以及人类活动的影响,水文序列蕴含了大量多界面交互叠加信息,使其过程表现出高度非线性与非平稳特征。因此,如何挖掘、分析水文序列中的隐藏信息及局部时变特征一直是水文学领域研究的热点和难点。经验模态分解(EMD... 受气候变化、生态演替以及人类活动的影响,水文序列蕴含了大量多界面交互叠加信息,使其过程表现出高度非线性与非平稳特征。因此,如何挖掘、分析水文序列中的隐藏信息及局部时变特征一直是水文学领域研究的热点和难点。经验模态分解(EMD)自提出以来便迅速受到各界学者们的广泛关注,近年来在水文领域中的应用更突显了其处理非线性、非平稳数据的优越性。本文梳理了EMD的基本理论、方法特性及现存问题,总结了5种发展较为成熟且应用广泛的EMD/类EMD扩展方法,包括希尔伯特-黄变换、集合经验模态分解、多元经验模态分解、极点对称模态分解及变分模态分解。随后通过水文序列的多时空尺度分析、趋势检验和模型预测3个方面,综述了EMD及其扩展方法的应用研究现状。最后,对其在水文学中的应用研究进行了展望,并就EMD的理论框架、水文变异性分析及区域多时空尺度研究提出了具体建议。 展开更多
关键词 数据挖掘 多时空尺度分析 水文变异性分析 趋势检验 水文预报
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基于多变量M-K检验的北江流域降水趋势分析 被引量:36
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作者 王乐 刘德地 +2 位作者 李天元 王家生 李凌云 《水文》 CSCD 北大核心 2015年第4期85-90,共6页
降水是北江流域水资源的主要来源,因此研究北江流域降水趋势有利于水资源合理规划和实现可持续利用,但目前的趋势分析主要以单变量趋势检验为主,对多变量的趋势分析研究较少。基于此,分别采用单变量和多变量M-K检验趋势分析方法,针对北... 降水是北江流域水资源的主要来源,因此研究北江流域降水趋势有利于水资源合理规划和实现可持续利用,但目前的趋势分析主要以单变量趋势检验为主,对多变量的趋势分析研究较少。基于此,分别采用单变量和多变量M-K检验趋势分析方法,针对北江流域6个代表性气象站点1959~2009年逐日降水资料,以各站的年降水量、年降水天数和年最大降水量三个变量为主要研究对象,分析得到北江流域的降水变化整体趋势。结果表明,仁化站、韶关站、乐昌站、连州站和广宁站的变化趋势不显著,清远站的变化趋势显著。在整体趋势分析方面,多变量趋势分析方法可同时考虑降水的多重属性特点,从而可更好分析流域降水整体趋势。 展开更多
关键词 降水 多变量趋势分析 MANN-KENDALL检验 北江流域
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蒙阴流域主要水文要素演变规律及归因分析
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作者 姚鸿韬 李彬权 +2 位作者 仇知雨 赵建飞 梁忠民 《水电能源科学》 北大核心 2025年第2期33-37,共5页
研究水文要素的演变规律及其变化归因,对于水资源管理及洪旱灾害防治具有重要意义。以山东省蒙阴流域为研究区域,采用线性趋势法、Mann-Kendall趋势检验法、Pettitt检验法和BG启发式分割算法,对1970~2020年汛期降水量、最大1 d洪量和年... 研究水文要素的演变规律及其变化归因,对于水资源管理及洪旱灾害防治具有重要意义。以山东省蒙阴流域为研究区域,采用线性趋势法、Mann-Kendall趋势检验法、Pettitt检验法和BG启发式分割算法,对1970~2020年汛期降水量、最大1 d洪量和年最大洪峰模数进行趋势和突变检验,对比2010~2020年降雨径流关系与山东省已有水文图集成果,对蒙阴流域水文要素演变规律及其归因进行分析。结果表明,蒙阴流域1970~2020年各水文要素均未发生显著突变,汛期降水量呈不显著上升趋势,最大1 d洪量和年最大洪峰模数呈不显著下降趋势;与已有水文图集成果相比,在相同的降雨条件下,蒙阴流域现阶段次洪径流深呈减小趋势;蒙阴流域水文要素演变受水库工程影响较小,土地利用变化和社会经济发展是其主要驱动因素。 展开更多
关键词 趋势检验 突变检验 降雨径流关系 归因分析 蒙阴流域
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基于DFA和M-K检验的高层建筑沉降变形趋势判断研究 被引量:1
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作者 李辉 鞠兴华 《甘肃科学学报》 2019年第2期70-75,133,共7页
为提高高层建筑沉降变形趋势判断的准确性,并探讨DFA和M-K检验在高层建筑沉降变形趋势判断中的适用性,从DFA和M-K检验的基本原理出发,构建了2个方法联合应用的高层建筑沉降变形趋势判断模型,并进一步探讨分析了AR(1)模型剔除沉降序列自... 为提高高层建筑沉降变形趋势判断的准确性,并探讨DFA和M-K检验在高层建筑沉降变形趋势判断中的适用性,从DFA和M-K检验的基本原理出发,构建了2个方法联合应用的高层建筑沉降变形趋势判断模型,并进一步探讨分析了AR(1)模型剔除沉降序列自相关性对分析结果的影响。通过2个实例的应用检验,得出DFA和M-K检验在高层建筑沉降变形趋势判断中的一致性较好,说明2种方法均能有效且准确的判断高层建筑的沉降变形趋势;同时,AR(1)模型能很好的剔除沉降序列的自相关性,减弱变形趋势判断的显著性,达到了提高分析结果可靠性的目的。通过研究,验证了DFA和M-K检验在高层建筑沉降变形趋势判断中的适用性,为2种方法的跨学科应用积累了经验,具有一定的参考价值。 展开更多
关键词 高层建筑 非趋势波动分析 m-k检验 沉降变形 趋势判断
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深部地质钻进过程钻速时序融合建模方法
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作者 周洋 陆承达 +4 位作者 吴敏 陈鑫 姚宁平 宋海涛 张幼振 《煤田地质与勘探》 北大核心 2025年第2期223-232,共10页
【目的】钻速是衡量钻进效率的关键指标,构建准确的钻速模型对于优化钻进过程、减少钻进成本具有重要意义。然而,深部地质钻进面临非线性、非凸优化、多工况及时序变化等挑战,传统建模方法难以适应复杂地质环境。【方法】为解决上述难题... 【目的】钻速是衡量钻进效率的关键指标,构建准确的钻速模型对于优化钻进过程、减少钻进成本具有重要意义。然而,深部地质钻进面临非线性、非凸优化、多工况及时序变化等挑战,传统建模方法难以适应复杂地质环境。【方法】为解决上述难题,提出一种结合时序调节的钻速融合建模方法。首先,利用支持向量回归构建了钻速基础模型,用于解决钻速变化带来的非线性问题。接着,设计一种改进的蜣螂优化算法,通过权重融合、改进的回声定位、改进的局部迭代搜索与最佳解重更新策略,来解决模型参数设计面临的非凸优化问题。此外,采用基于模糊C均值聚类与Mann-Kendall趋势检验的时序调节方法,对模型输出进行时序调节,以适应钻速的时序变化。【结果和结论】结果表明:(1)改进的蜣螂优化方法11个基准测试函数中展现出更好的效果,表明其能够有效解决模型参数设计问题。(2)基于实际钻进数据的仿真结果也说明了建立的钻速模型在两个井段中均取得了最佳的效果,时序调节后的模型在两个井段中的预测趋势正确率也分别提升到了80%和87.5%。(3)在微型钻进实验系统的测试中,建立的钻速模型在不同的岩石样本中均达到最高精度。建立的钻速模型能有效应对复杂的地质环境变化,为深部地质钻进过程控制奠定良好基础。 展开更多
关键词 钻速建模 蜣螂优化算法 趋势检验 时序调节 深部地质钻进
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湖南省带量采购和分级管理政策对碳青霉烯类抗生素利用的影响
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作者 吴泽华 陈君宇 +7 位作者 许林勇 明煜鑫 周宇松 黄勋 付陈超 王朝晖 刘世坤 李佐军 《中国感染控制杂志》 北大核心 2025年第1期105-112,共8页
目的探索抗菌药物带量采购和分级管理政策对碳青霉烯类抗生素利用的影响。方法采用Mann-Kendall趋势检验分析各级医疗机构碳青霉烯类抗生素用药频度(DDDs)、采购金额(Cost)、药品日均费用(DDDc)、每天每1000居民用药频度(DID)的变化趋势... 目的探索抗菌药物带量采购和分级管理政策对碳青霉烯类抗生素利用的影响。方法采用Mann-Kendall趋势检验分析各级医疗机构碳青霉烯类抗生素用药频度(DDDs)、采购金额(Cost)、药品日均费用(DDDc)、每天每1000居民用药频度(DID)的变化趋势,以2020年5月1日为带量采购政策的干预分界点,以2021年9月作为分级管理目录的干预分界点,采用间断时间序列分析法研究带量采购和分级管理政策对碳青霉烯类抗生素临床用药的影响。结果在带量采购政策执行后,碳青霉烯类抗生素DDDs、DID明显上升,但长期趋势变化不显著;与政策执行前相比,碳青霉烯类抗生素的Cost和DDDc瞬时下降,DDDc长期趋势变化显著,但Cost长期趋势变化不显著。分级管理目录更新后,碳青霉烯类抗生素DDDs、Cost瞬时下降,但长期下降趋势不显著,并且DDDc呈长期上升趋势。结论带量采购政策降低了碳青霉烯类抗生素DDDc,短期内降低了Cost;但对DDDs、Cost、DID的长期影响有限;分级管理对医疗机构碳青霉烯类抗生素的利用影响有限。 展开更多
关键词 碳青霉烯类抗生素 抗菌药物带量采购 抗菌药物分级管理 药物利用评价 Mann-Kendall趋势检验 间断时间序列分析
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不同含盐量下冻土电渗过程分析及其机理研究
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作者 赵芯雨 张泽 +3 位作者 张圣嵘 金豆豆 崔健 翟金榜 《冰川冻土》 2025年第1期153-162,共10页
多年冻土地区中广泛分布着盐渍土,受季节性气候影响盐渍土地区的工程基础常常受到盐分侵蚀,这是此区域主要工程灾害之一。研究发现,冻结土在电场作用下,极性水分子与阳离子从阳极向阴极移动,当溶液浓度增高时,更有利于水分迁移。因此,... 多年冻土地区中广泛分布着盐渍土,受季节性气候影响盐渍土地区的工程基础常常受到盐分侵蚀,这是此区域主要工程灾害之一。研究发现,冻结土在电场作用下,极性水分子与阳离子从阳极向阴极移动,当溶液浓度增高时,更有利于水分迁移。因此,可通过电渗的方法控制水分的聚集位置,解决冻土中因水分积聚而形成的冻害。结果表明:试验环境在-4℃下,不同含盐量试样通过粒子数量和未冻水含量影响着电流趋势——未冻水中离子浓度越大,土体导电性越强,电流峰值越大;未冻水含量增多,离子迁移通道也增多,且到达峰值时间缩短。对比通电结束后的水分迁移量,添加盐分能有效提高水分迁移量,但是0.20%、0.25%、0.30%三个浓度氯化钠盐渍土的水分迁移量区别不明显,即不同类型(低含盐度)冻土对水分迁移量的影响可以忽略。试验结果可为判别冻土地区应用电渗法适宜性提供一定的参考依据。 展开更多
关键词 电渗试验 冻土 含盐量 电流趋势 水分迁移
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1960—2020年贵州省极端气温指数时空演变特征及其影响因素分析
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作者 刘祥周 肖丽英 +2 位作者 高桂青 成玉祥 李路雨 《水利水电技术(中英文)》 北大核心 2025年第1期39-50,共12页
【目的】贵州省极端气候事件的频率和持续性因其独特的地形和多样气候而显著加剧,但目前关于该省极端气温方面的研究尚不完善。为掌握极端气温指数的时空变化特征并明确其主要影响因素,基于1960—2020年29个气象站气温及大尺度气候指数(... 【目的】贵州省极端气候事件的频率和持续性因其独特的地形和多样气候而显著加剧,但目前关于该省极端气温方面的研究尚不完善。为掌握极端气温指数的时空变化特征并明确其主要影响因素,基于1960—2020年29个气象站气温及大尺度气候指数(PDO、ENSO、SOI、AMO)等数据,针对5个极端气温指数,【方法】运用线性趋势法、Mann-Kendall趋势检验、R/S分析了贵州省极端气温时空演变特征及未来趋势,利用相关分析及小波分析揭示了极端气温指数与大尺度气候指数等因素的联系。【结果】结果表明:(1)时间变化上,寒潮持续时间和霜冻时间显著减少,然而,月极端最低和最高气温以及夏日数均表现出上升趋势;极端气温指数的突变均集中于20世纪末至21世纪初;在未来5年内,极端气温指数将继续保持这种趋势;空间分布上,自西向东方向,低温指数的多年平均值逐渐减少,高温指数则逐渐增加;(2)寒潮持续指数发生突变很可能受到ENSO、SOI较长年际周期(2~16 a)的影响,极端高温指数则受到较短周期(2~4 a)的影响。另外,霜冻日数、月极端最低气温与海拔呈显著负相关性。【结论】极端气温指数变化的影响因素主要是气候与海拔,另外还有人类活动方面。研究结果为灾害预防与对地方气候影响等决策提供科学依据。 展开更多
关键词 空间差异 R/S分析 相关性分析 极端气温指数 贵州省 气候变化 Mann-Kendall趋势检验 时空变化
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