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D-S理论和Markov链组合的桥梁性能退化预测研究
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作者 杨国俊 田里 +2 位作者 唐光武 毛建博 杜永峰 《应用数学和力学》 CSCD 北大核心 2024年第4期416-428,共13页
为准确预测桥梁性能退化,考虑到数据随机性和微小扰动发生状态跳跃,提出了一种D-S(Dempster-Shafer)证据理论和Markov链组合的桥梁性能退化组合预测模型和性能退化率的概念.该模型基于指数平滑(exponential smoothing,ES)方法获得新的... 为准确预测桥梁性能退化,考虑到数据随机性和微小扰动发生状态跳跃,提出了一种D-S(Dempster-Shafer)证据理论和Markov链组合的桥梁性能退化组合预测模型和性能退化率的概念.该模型基于指数平滑(exponential smoothing,ES)方法获得新的预测数据序列,并利用Markov链和D-S理论不断进行优化,从而实现桥梁性能退化的组合预测.实际工程的应用结果表明:性能退化率可以直观地表征在梁性能退化的速度.其次,该模型的平均相对误差为1.54%,较于回归、灰色和模糊加权Markov链模型,精度分别提高了1.11%,0.88%和2.8%,而后验差比值为0.242,小于0.35;模型的标准差为9.021,相比其他模型分别减小了3.978,3.405和7.500,而变异系数为0.109,均小于其他模型,验证了组合预测模型在精度和稳定性方面的优越性,可为在役桥梁结构性能退化预测与维护提供理论基础. 展开更多
关键词 桥梁工程 性能退化预测 D-s证据理论 MARKOV链 组合预测模型 桥梁性能退化率
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基于D-S证据理论的岩爆预测方法研究
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作者 高永涛 朱强 +1 位作者 吴顺川 王勇兵 《东北大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第2期244-251,共8页
为了有效预测岩爆,提出基于D-S证据理论的岩爆预测方法.首先,选取与岩爆发生相关的6个指标因素作为证据体,并通过模糊物元框架和正态型隶属度函数构建证据体的基本概率分配.然后,利用K均值将证据体分类,并提出簇内证据用传统方式融合而... 为了有效预测岩爆,提出基于D-S证据理论的岩爆预测方法.首先,选取与岩爆发生相关的6个指标因素作为证据体,并通过模糊物元框架和正态型隶属度函数构建证据体的基本概率分配.然后,利用K均值将证据体分类,并提出簇内证据用传统方式融合而簇间证据用权重方式融合的组合融合规则,以减轻高冲突证据融合的不利影响.最后,将模型应用在秦岭终南山公路隧道2号竖井工程,且与经验方法对比.为了分析预测过程的不确定性和估计岩爆发生概率,采用蒙特卡洛模拟进行抽样仿真,并通过Spearman秩相关系数衡量输入指标的全局敏感性.研究结果表明:输入指标在不同的岩爆案例的影响程度差异较大且方向不同;5个岩爆案例的发生概率在40.8%~70.1%之间.该模型表现出优异的预测分类性能,可为深埋地下工程岩爆预测提供参考. 展开更多
关键词 岩石力学 岩爆预测 D-s证据理论 模糊物元 K均值
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S-100β CysC和NF-κB对急性缺血性脑卒中患者静脉溶栓后出血转化的预测价值
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作者 李鹤 李樱 李磊 《中国实用神经疾病杂志》 2024年第4期415-419,共5页
目的 探讨急性缺血性脑卒中(AIS)外周血中S-100β、CysC和NF-κB水平对静脉溶栓后出血转化的影响及预测价值。方法 收集2019-03—2022-03接受溶栓治疗的AIS患者140例,根据溶栓后24 h是否发生出血转化(HT)将患者分为非HT组(n=112)和HT组(... 目的 探讨急性缺血性脑卒中(AIS)外周血中S-100β、CysC和NF-κB水平对静脉溶栓后出血转化的影响及预测价值。方法 收集2019-03—2022-03接受溶栓治疗的AIS患者140例,根据溶栓后24 h是否发生出血转化(HT)将患者分为非HT组(n=112)和HT组(n=28)。比较2组一般临床资料,采用多因Logistic回归分析影响HT发生的危险因素,受试者工作特征(ROC)曲线评估S-100β、CysC和NF-κB预测HT发生的价值。结果 HT组与非HT组相比,患者年龄、发病至溶栓时间、房颤、TOAST分型、C反应蛋白、凝血酶原时间、S-100β、CysC、NF-κB、白质高信号和脑微出血等均有统计学差异(P<0.05)。Logistic多因素回归分析显示,房颤、S-100β、CysC和NF-κB为影响HT发生的危险因素。S-100β、CysC和NF-κB预测AIS患者静脉溶栓后出血转化的曲线下面积分别为0.915(0.902~0.923)、0.874(0.856~0.882)和0.789(0.771~0.796),均具有一定的预测价值。结论 S-100β、CysC和NF-κB为AIS患者静脉溶栓后HT发生的危险因素,对HT发生具有一定的预测价值。 展开更多
关键词 急性缺血性脑卒中 静脉溶栓 出血转化 中枢神经特异蛋白 胱抑素C 核因子ΚB 外周血 危险因素 预测价值
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Progress of MJO Prediction at CMA from Phase I to Phase II of the Sub-Seasonal to Seasonal Prediction Project
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作者 Junchen YAO Xiangwen LIU +3 位作者 Tongwen WU Jinghui YAN Qiaoping LI Weihua JIE 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第10期1799-1815,共17页
As one of the participants in the Subseasonal to Seasonal(S2S)Prediction Project,the China Meteorological Administration(CMA)has adopted several model versions to participate in the S2S Project.This study evaluates th... As one of the participants in the Subseasonal to Seasonal(S2S)Prediction Project,the China Meteorological Administration(CMA)has adopted several model versions to participate in the S2S Project.This study evaluates the models’capability to simulate and predict the Madden-Julian Oscillation(MJO).Three versions of the Beijing Climate Center Climate System Model(BCC-CSM)are used to conduct historical simulations and re-forecast experiments(referred to as EXP1,EXP1-M,and EXP2,respectively).In simulating MJO characteristics,the newly-developed high-resolution BCC-CSM outperforms its predecessors.In terms of MJO prediction,the useful prediction skill of the MJO index is enhanced from 15 days in EXP1 to 22 days in EXP1-M,and further to 24 days in EXP2.Within the first forecast week,the better initial condition in EXP2 largely contributes to the enhancement of MJO prediction skill.However,during forecast weeks 2–3,EXP2 shows little advantage compared with EXP1-M because the increased skill at MJO initial phases 6–7 is largely offset by the degraded skill at MJO initial phases 2–3.Particularly at initial phases 2–3,EXP1-M skillfully captures the wind field and Kelvin-wave response to MJO convection,leading to the highest prediction skill of the MJO.Our results reveal that,during the participation of the CMA models in the S2S Project,both the improved model initialization and updated model physics played positive roles in improving MJO prediction.Future efforts should focus on improving the model physics to better simulate MJO convection over the Maritime Continent and further improve MJO prediction at long lead times. 展开更多
关键词 Madden-Julian Oscillation(MJO) subseasonal to seasonal(s2s) prediction skill improvement initial phase
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Comparison and development of machine learning for thalidomideinduced peripheral neuropathy prediction of refractory Crohn’s disease in Chinese population
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作者 Jing Mao Kang Chao +9 位作者 Fu-Lin Jiang Xiao-Ping Ye Ting Yang Pan Li Xia Zhu Pin-Jin Hu Bai-Jun Zhou Min Huang Xiang Gao Xue-Ding Wang 《World Journal of Gastroenterology》 SCIE CAS 2023年第24期3855-3870,共16页
BACKGROUND Thalidomide is an effective treatment for refractory Crohn’s disease(CD).However,thalidomide-induced peripheral neuropathy(TiPN),which has a large individual variation,is a major cause of treatment failure... BACKGROUND Thalidomide is an effective treatment for refractory Crohn’s disease(CD).However,thalidomide-induced peripheral neuropathy(TiPN),which has a large individual variation,is a major cause of treatment failure.TiPN is rarely predictable and recognized,especially in CD.It is necessary to develop a risk model to predict TiPN occurrence.AIM To develop and compare a predictive model of TiPN using machine learning based on comprehensive clinical and genetic variables.METHODS A retrospective cohort of 164 CD patients from January 2016 to June 2022 was used to establish the model.The National Cancer Institute Common Toxicity Criteria Sensory Scale(version 4.0)was used to assess TiPN.With 18 clinical features and 150 genetic variables,five predictive models were established and evaluated by the confusion matrix receiver operating characteristic curve(AUROC),area under the precision-recall curve(AUPRC),specificity,sensitivity(recall rate),precision,accuracy,and F1 score.RESULTS The top-ranking five risk variables associated with TiPN were interleukin-12 rs1353248[P=0.0004,odds ratio(OR):8.983,95%confidence interval(CI):2.497-30.90],dose(mg/d,P=0.002),brainderived neurotrophic factor(BDNF)rs2030324(P=0.001,OR:3.164,95%CI:1.561-6.434),BDNF rs6265(P=0.001,OR:3.150,95%CI:1.546-6.073)and BDNF rs11030104(P=0.001,OR:3.091,95%CI:1.525-5.960).In the training set,gradient boosting decision tree(GBDT),extremely random trees(ET),random forest,logistic regression and extreme gradient boosting(XGBoost)obtained AUROC values>0.90 and AUPRC>0.87.Among these models,XGBoost and GBDT obtained the first two highest AUROC(0.90 and 1),AUPRC(0.98 and 1),accuracy(0.96 and 0.98),precision(0.90 and 0.95),F1 score(0.95 and 0.98),specificity(0.94 and 0.97),and sensitivity(1).In the validation set,XGBoost algorithm exhibited the best predictive performance with the highest specificity(0.857),accuracy(0.818),AUPRC(0.86)and AUROC(0.89).ET and GBDT obtained the highest sensitivity(1)and F1 score(0.8).Overall,compared with other state-of-the-art classifiers such as ET,GBDT and RF,XGBoost algorithm not only showed a more stable performance,but also yielded higher ROC-AUC and PRC-AUC scores,demonstrating its high accuracy in prediction of TiPN occurrence.CONCLUSION The powerful XGBoost algorithm accurately predicts TiPN using 18 clinical features and 14 genetic variables.With the ability to identify high-risk patients using single nucleotide polymorphisms,it offers a feasible option for improving thalidomide efficacy in CD patients. 展开更多
关键词 Thalidomide-induced peripheral neuropathy Refractory Crohn’s disease Neurotoxicity prediction models Machine learning Gene polymorphisms
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Prediction of the Wastewater’s pH Based on Deep Learning Incorporating Sliding Windows
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作者 Aiping Xu Xuan Zou Chao Wang 《Computer Systems Science & Engineering》 SCIE EI 2023年第10期1043-1059,共17页
To protect the environment,the discharged sewage’s quality must meet the state’s discharge standards.There are many water quality indicators,and the pH(Potential of Hydrogen)value is one of them.The natural water’s... To protect the environment,the discharged sewage’s quality must meet the state’s discharge standards.There are many water quality indicators,and the pH(Potential of Hydrogen)value is one of them.The natural water’s pH value is 6.0–8.5.The sewage treatment plant uses some data in the sewage treatment process to monitor and predict whether wastewater’s pH value will exceed the standard.This paper aims to study the deep learning prediction model of wastewater’s pH.Firstly,the research uses the random forest method to select the data features and then,based on the sliding window,convert the data set into a time series which is the input of the deep learning training model.Secondly,by analyzing and comparing relevant references,this paper believes that the CNN(Convolutional Neural Network)model is better at nonlinear data modeling and constructs a CNN model including the convolution and pooling layers.After alternating the combination of the convolutional layer and pooling layer,all features are integrated into a full-connected neural network.Thirdly,the number of input samples of the CNN model directly affects the prediction effect of the model.Therefore,this paper adopts the sliding window method to study the optimal size.Many experimental results show that the optimal prediction model can be obtained when alternating six convolutional layers and three pooling layers.The last full-connection layer contains two layers and 64 neurons per layer.The sliding window size selects as 12.Finally,the research has carried out data prediction based on the optimal CNN deep learning model.The predicted pH of the sewage is between 7.2 and 8.6 in this paper.The result is applied in the monitoring system platform of the“Intelligent operation and maintenance platform of the reclaimed water plant.” 展开更多
关键词 Deep learning wastewater’s pH convolution neural network(CNN) prediction sliding window
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2013年岷县漳县M_(S)6.6地震和2017年九寨沟M_(S)7.0地震震前地球物理观测异常空间分布机理分析
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作者 杨晨艺 石富强 +4 位作者 季灵运 杨宜海 苏利娜 杨敏 郑怡 《地震学报》 CSCD 北大核心 2024年第2期307-326,共20页
对甘东南地区2013年岷县漳县M_(S)6.6地震和2017年九寨沟M_(S)7.0地震震前地球物理观测异常特征进行总结梳理。根据活动构造单元对地球物理观测台站进行区域划分,统计了相关构造单元上异常的数量和百分比,以及不同学科震前异常数量、百... 对甘东南地区2013年岷县漳县M_(S)6.6地震和2017年九寨沟M_(S)7.0地震震前地球物理观测异常特征进行总结梳理。根据活动构造单元对地球物理观测台站进行区域划分,统计了相关构造单元上异常的数量和百分比,以及不同学科震前异常数量、百分比、异常持续时间等特征,并对异常的空间分布和机理进行分析,讨论了活动构造对异常分布的影响、异常强度与震源机制及断层应力之间的关系。结果表明:①2013年岷县漳县M_(S)6.6地震比2017年九寨沟M_(S)7.0地震震前地球物理观测异常百分比高,两次地震的震前电磁异常和跨断层水准测量异常均较为显著,而流体异常不明显;②震前地球物理观测异常分布与活动构造相关,2013年岷县漳县M_(S)6.6地震震前异常主要集中在东昆仑-西秦岭断裂带和六盘山-海原断裂带,2017年九寨沟M_(S)7.0地震震前异常则主要集中在龙门山断裂带和东昆仑-西秦岭断裂带;③两次地震震前地球物理观测异常分布均与GNSS速度场分布特征有较好的对应关系;④安德森断层应力模式解释了2013年岷县漳县M_(S)6.6地震(逆冲型)比2017年九寨沟M_(S)7.0地震(走滑型)的形成需要更多的应力积累,因此2013年岷县漳县M_(S)6.6地震虽然震级较小但震前异常更显著。 展开更多
关键词 2013年岷县漳县Ms6.6地震 2017年九寨沟Ms7.0地震 观测异常 地震预测
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Real-time prediction of earthquake potential damage:A case study for the January 8,2022 M_(S) 6.9 Menyuan earthquake in Qinghai,China
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作者 Jindong Song Jingbao Zhu +2 位作者 Yongxiang Wei Shuilong Li Shanyou Li 《Earthquake Research Advances》 CSCD 2023年第1期52-60,共9页
It is critical to determine whether a site has potential damage in real-time after an earthquake occurs,which is a challenge in earthquake disaster reduction.Here,we propose a real-time Earthquake Potential Damage pre... It is critical to determine whether a site has potential damage in real-time after an earthquake occurs,which is a challenge in earthquake disaster reduction.Here,we propose a real-time Earthquake Potential Damage predictor(EPDor)based on predicting peak ground velocities(PGVs)of sites.The EPDor is composed of three parts:(1)predicting the magnitude of an earthquake and PGVs of triggered stations based on the machine learning prediction models;(2)predicting the PGVs at distant sites based on the empirical ground motion prediction equation;(3)generating the PGV map through predicting the PGV of each grid point based on an interpolation process of weighted average based on the predicted values in(1)and(2).We apply the EPDor to the 2022 M_(S) 6.9 Menyuan earthquake in Qinghai Province,China to predict its potential damage.Within the initial few seconds after the first station is triggered,the EPDor can determine directly whether there is potential damage for some sites to a certain degree.Hence,we infer that the EPDor has potential application for future earthquakes.Meanwhile,it also has potential in Chinese earthquake early warning system. 展开更多
关键词 Earthquake early warning Potential damage Machine learning 2022 M_(s)6.9 Menyuan earthquake Magnitude estimation On-site peak ground velocity prediction
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基于S变换的临汾水平摆倾斜观测数据年变信息提取及预测指标确定
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作者 姚林鹏 宫静芝 +3 位作者 成诚 刘国俊 李芸 李颖 《科学技术创新》 2024年第5期45-48,共4页
临汾台水平摆多年来监测能力及资料的映震能力备受关注,为推进长周期破年变分析在临汾台水平摆资料的应用,本文利用一种基于S变换时频分析方法的破年变信息分离提取方法,采用双向非对称阈值策略,结合R值评分及Molchan图表法,构建了临汾... 临汾台水平摆多年来监测能力及资料的映震能力备受关注,为推进长周期破年变分析在临汾台水平摆资料的应用,本文利用一种基于S变换时频分析方法的破年变信息分离提取方法,采用双向非对称阈值策略,结合R值评分及Molchan图表法,构建了临汾水平摆东西测项破年变预测指标,给出了长周期信号变化(ANA)和短周期信号变化(ONA)对于不同震级档的最佳阈值、最佳预报范围、最佳预报时窗,预报效能R值均大于R0值,可信度高。其中ANA指标对于500 km以内的ML≥5级的预报效能最好。 展开更多
关键词 水平摆 s变换 破年变 预测指标
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Not Relying on the Newton Gravitational Constant Gives More Accurate Gravitational Predictions
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作者 Espen Gaarder Haug 《Journal of Applied Mathematics and Physics》 2023年第10期3124-3158,共35页
The Newton gravitational constant is considered a cornerstone of modern gravity theory. Newton did not invent or use the gravity constant;it was invented in 1873, about the same time as it became standard to use the k... The Newton gravitational constant is considered a cornerstone of modern gravity theory. Newton did not invent or use the gravity constant;it was invented in 1873, about the same time as it became standard to use the kilogram mass definition. We will claim that G is just a term needed to correct the incomplete kilogram definition so to be able to make gravity predictions. But there is another way;namely, to directly use a more complete mass definition, something that in recent years has been introduced as collision-time and a corresponding energy called collision-length. The collision-length is quantum gravitational energy. We will clearly demonstrate that by working with mass and energy based on these new concepts, rather than kilogram and the gravitational constant, one can significantly reduce the uncertainty in most gravity predictions. 展开更多
关键词 Gravity predictions Reduction of Errors Newton’s Gravitational Constant Collision space-Time Cavendish Apparatus Planck Length Planck Time
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基于CLUE-S模型的吴忠市土地利用时空演变及多情景模拟预测
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作者 吕文清 马晓芳 《南方农机》 2024年第2期20-25,共6页
【目的】研究不同情景下的未来土地利用时空演变格局,为合理利用土地资源、科学规划国土空间开发格局和区域高质量发展提供助力。【方法】研究团队以宁夏回族自治区吴忠市为研究对象,选取2000年、2010年和2020年3期土地利用数据,运用土... 【目的】研究不同情景下的未来土地利用时空演变格局,为合理利用土地资源、科学规划国土空间开发格局和区域高质量发展提供助力。【方法】研究团队以宁夏回族自治区吴忠市为研究对象,选取2000年、2010年和2020年3期土地利用数据,运用土地利用转移矩阵、CLUE-S模型,分析研究区2000—2020年土地利用变化特征,模拟自然增长情景、生态保护情景和经济增长情景下2030年吴忠市土地利用演变特征。【结果】1)2000—2020年吴忠市草地面积占比最大,其次是耕地和未利用地,建设用地面积不断增长;建设用地面积变化最快,并以耕地转化为建设用地为主。2)2030年建设用地面积在自然增长情景下将会减少,生态保护情景下林地面积增幅较大,经济增长情景下各土地利用类型变化较小。3)在3种情景下,吴忠市2030年土地利用结构仍然以耕地、林地、草地为主,建设用地面积在生态保护情景和经济增长情景下将呈增长的趋势,在自然增长情景下将呈减少趋势。【结论】生态保护情景下的预测结果更符合国土空间规划要求和经济社会发展的需求。该研究成果对推动吴忠市未来土地利用格局规划具有重要意义。 展开更多
关键词 吴忠市 土地利用 转移矩阵 CLUE-s模型 多情景预测
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慢性心力衰竭患者血清sICAM-1、Lp-PLA2、CatS的表达水平及对近期预后的预测价值 被引量:1
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作者 陈刚 信鹏程 +1 位作者 陈文宽 陈红卫 《中国循证心血管医学杂志》 2023年第2期210-212,217,共4页
目的探讨慢性心力衰竭(心衰)患者血清可溶性细胞黏附分子-1(sICAM-1)、脂蛋白相关磷脂酶A2(Lp-PLA2)、蛋白酶S(CatS)的表达水平及对近期预后的预测价值。方法选择2021年1月至2022年6月于郑州市第七人民医院心内科就诊的85例慢性心衰患... 目的探讨慢性心力衰竭(心衰)患者血清可溶性细胞黏附分子-1(sICAM-1)、脂蛋白相关磷脂酶A2(Lp-PLA2)、蛋白酶S(CatS)的表达水平及对近期预后的预测价值。方法选择2021年1月至2022年6月于郑州市第七人民医院心内科就诊的85例慢性心衰患者作为研究对象(病例组),另选取我院同期体检的健康人群80例为对照组,分析两组患者血清sICAM-1、Lp-PLA2、CatS水平变化及对近期预后的预测价值。结果病例组患者血清sICAM-1、Lp-PLA2、CatS水平显著高于对照组,差异有统计学意义(P<0.05);NYHA分级心功能Ⅱ级患者血清sICAM-1、Lp-PLA2、CatS水平显著低于心功能Ⅲ级、Ⅳ级患者,心功能Ⅲ级患者血清sICAM-1、Lp-PLA2、CatS水平显著低于心功能Ⅳ级患者,差异有统计学意义(P<0.05);预后不良组患者血清sICAM-1、Lp-PLA2、CatS水平显著高于预后良好组,差异有统计学意义(P<0.05)。ROC曲线分析显示,血清sICAM-1预测慢性心衰预后的AUC为0.944,灵敏度为78.30%,特异度为87.10%,截断值为568.44μg/L;血清Lp-PLA2预测慢性心衰预后的AUC为0.974,灵敏度为71.00%,特异度为92.90%,截断值为74.23 ng/ml;血清CatS预测慢性心衰预后的AUC为0.818,灵敏度为63.10%,特异度为70.60%,截断值为57.61 ng/ml(P<0.05)。结论慢性心衰患者中血清sICAM-1、Lp-PLA2、CatS表达异常,与病情程度关系密切,可作为评估预后的指标之一。 展开更多
关键词 慢性心力衰竭 可溶性细胞黏附分子-1 脂蛋白相关磷脂酶A2 蛋白酶s 预测价值
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基于Faster R-CNN的密集人群检测算法 被引量:2
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作者 邹斌 张聪 《计算机应用》 CSCD 北大核心 2023年第1期61-66,共6页
为提高拥挤场景下的人群检测准确率,提出一种基于改进Faster R-CNN的密集人群检测算法。首先,在特征提取阶段添加空间与通道注意力机制,使用加强的双向特征金字塔网络(S-BiFPN)替代原网络中的多尺度特征金字塔(FPN),使网络对重要特征进... 为提高拥挤场景下的人群检测准确率,提出一种基于改进Faster R-CNN的密集人群检测算法。首先,在特征提取阶段添加空间与通道注意力机制,使用加强的双向特征金字塔网络(S-BiFPN)替代原网络中的多尺度特征金字塔(FPN),使网络对重要特征进行自主学习并加强对图像深层特征的提取;其次,引入多实例预测(MIP)算法对实例进行预测,以避免模型对拥挤场景下的目标造成漏检;最后,对模型中的非极大值抑制(NMS)进行优化,并额外增设一个交并比(IoU)阈值,以对检测结果的干扰项进行精确抑制。在开源的密集人群检测数据集上进行测试的结果显示,相较于原Faster R-CNN算法,所提算法的平均精度(AP)提升5.6%,Jaccard指数值提升3.2%。所提算法具有较高检测精度和稳定性,可以满足密集场景人群检测的需求。 展开更多
关键词 密集人群检测 Faster R-CNN 注意力机制 多实例预测 加强的双向特征金字塔网络
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基于B-S分布的智能电能表寿命预计方法研究
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作者 程磊 陆蔺 《电测与仪表》 北大核心 2023年第3期188-194,共7页
针对目前智能电能表寿命预计普遍采用Weibull分布的情况,文中介绍了概率物理方法中一个重要的失效模型:B-S疲劳寿命分布及其可靠性分析,并推导出两参数B-S分布的极大似然估计值及近似区间。B-S分布适合描述失效产品的寿命规律,主要应用... 针对目前智能电能表寿命预计普遍采用Weibull分布的情况,文中介绍了概率物理方法中一个重要的失效模型:B-S疲劳寿命分布及其可靠性分析,并推导出两参数B-S分布的极大似然估计值及近似区间。B-S分布适合描述失效产品的寿命规律,主要应用于疲劳失效以及电子产品性能退化失效的分析研究。文中将两参数B-S分布引入智能电能表寿命预计,对寿命数据是否来自两参数B-S分布总体的样本进行了拟合检验,采用极大似然法和最小二乘法对两参数B-S分布进行了参数估计,建立了基于B-S分布的寿命预计方法,通过实际算例验证了B-S分布寿命预计方法的实用性。文中研究内容对于电能表寿命预计、轮换周期的确定提供了一种新方法,同时对于电能表可靠性评价提供了新思路。 展开更多
关键词 B-s分布 智能电能表 寿命预计 拟合检验
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内源性H_(2)S、TAT、sPECAM-1对老年髋部骨折围术期下肢深静脉血栓形成的预测价值研究
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作者 叶欣 赵斌 刘志伟 《北京医学》 CAS 2023年第9期749-752,757,共5页
目的探讨内源性硫化氢(endogenous hydrogen sulfidem,H_(2)S)、血浆凝血酶-抗凝血酶复合物(thrombin/antithrombin complex,TAT)及可溶性血小板内皮细胞黏附分子-1(soluble platelet endothelial cell adhesion molecule 1,sPECAM-1)... 目的探讨内源性硫化氢(endogenous hydrogen sulfidem,H_(2)S)、血浆凝血酶-抗凝血酶复合物(thrombin/antithrombin complex,TAT)及可溶性血小板内皮细胞黏附分子-1(soluble platelet endothelial cell adhesion molecule 1,sPECAM-1)对老年髋部骨折围术期下肢深静脉血栓形成(deep vein thrombosis,DVT)的预测价值。方法选取2018年11月至2019年7月北京积水潭医院急诊科住院接受手术治疗的新发老年髋部骨折患者187例,随机抽取120例患者(建模集),采用多因素logistic回归方程分析建模集患者DVT的影响因素,并建立预测模型;将剩余67例患者纳入验证集,进行预测模型的内部验证。结果建模集120例患者中男39例(32.50%),女81例(67.50%);平均年龄(78.6±7.1)岁;BMI为(22.5±4.2)kg/m^(2)。多因素logisitic回归分析显示,BMI、发病至就诊的时间及TAT越高,H_(2)S及sPECAM-1越低的患者,越容易发生DVT(P<0.05)。建立的DVT风险预测模型为:logit(P)=0.130×BMI+0.010×发病至就诊的时间-0.098×H_(2)S+0.039×TAT-0.322×sPECAM-1-3.581。预测模型的ROC曲线的AUC为0.844(95%CI:0.774~0.915,P=0.000)。应用验证集数据对模型进行内部验证结果显示验证模型的ROC曲线的AUC为0.816(95%CI:0.713~0.919,P=0.000)。结论基于BMI、受伤至入院时间、TAT、H_(2)S和sPECAM-1等因素建立的模型对于预测老年髋部骨折患者围术期DVT的发生具有良好的筛查能力。 展开更多
关键词 内源性硫化氢 髋部骨折 深静脉血栓 预测模型 老年
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Prediction of disease course in inflammatory bowel diseases 被引量:2
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作者 Peter Laszlo Lakatos 《World Journal of Gastroenterology》 SCIE CAS CSCD 2010年第21期2589-2590,共2页
Clinical presentation at diagnosis and disease course of both Crohn's disease(CD) and ulcerative colitis are heterogeneous and variable over time.Since most patients have a relapsing course and most CD patients de... Clinical presentation at diagnosis and disease course of both Crohn's disease(CD) and ulcerative colitis are heterogeneous and variable over time.Since most patients have a relapsing course and most CD patients develop complications(e.g.stricture and/or perforation),much emphasis has been placed in the recent years on the determination of important predictive factors.The identification of these factors may eventually lead to a more personalized,tailored therapy.In this TOPIC HIGHLIGHT series,we provide an update on the available literature regarding important clinical,endoscopic,fecal,serological/routine laboratory and genetic factors.Our aim is to assist clinicians in the everyday practical decisionmaking when choosing the treatment strategy for their patients suffering from inflammatory bowel diseases. 展开更多
关键词 Inflammatory bowel disease Crohn’s disease Ulcerative colitis Disease course Predictive markers CLINICAL sEROLOGY GENETICs
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Implications from Subseasonal Prediction Skills of the Prolonged Heavy Snow Event over Southern China in Early 2008 被引量:2
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作者 Keyue ZHANG Juan LI +1 位作者 Zhiwei ZHU Tim LI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第11期1873-1888,共16页
An exceptionally prolonged heavy snow event(PHSE)occurred in southern China from 10 January to 3 February 2008,which caused considerable economic losses and many casualties.To what extent any dynamical model can predi... An exceptionally prolonged heavy snow event(PHSE)occurred in southern China from 10 January to 3 February 2008,which caused considerable economic losses and many casualties.To what extent any dynamical model can predict such an extreme event is crucial for disaster prevention and mitigation.Here,we found the three S2S models(ECMWF,CMA1.0 and CMA2.0)can predict the distribution and intensity of precipitation and surface air temperature(SAT)associated with the PHSE at 10-day lead and 10−15-day lead,respectively.The success is attributed to the models’capability in forecasting the evolution of two important low-frequency systems in the tropics and mid-latitudes[the persistent Siberian High and the suppressed phase of the Madden−Julian Oscillation(MJO)],especially in the ECMWF model.However,beyond the 15-day lead,the three models show almost no skill in forecasting this PHSE.The bias in capturing the two critical circulation systems is responsible for the low skill in forecasting the 2008 PHSE beyond the 15-day lead.On one hand,the models cannot reproduce the persistence of the Siberian High,which results in the underestimation of negative SAT anomalies over southern China.On the other hand,the models cannot accurately capture the suppressed convection of the MJO,leading to weak anomalous southerly and moisture transport,and therefore the underestimation of precipitation over southern China.The Singular Value Decomposition(SVD)analyses between the critical circulation systems and SAT/precipitation over southern China shows a robust historical relation,indicating the fidelity of the predictability sources for both regular events and extreme events(e.g.,the 2008 PHSE). 展开更多
关键词 prolonged heavy snow event s2s prediction models subseasonal prediction skill MJO siberian High
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Application of the value of nonlinear parameters H and ΔH in strong earthquake prediction 被引量:1
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作者 陈佩燕 《Acta Seismologica Sinica(English Edition)》 CSCD 1997年第2期38-48,共11页
Applicationofthevalueofnonlinearparame┐tersHandΔHinstrongearthquakepredic┐tionPEI-YANCHEN(陈佩燕)InstituteofGeo... Applicationofthevalueofnonlinearparame┐tersHandΔHinstrongearthquakepredic┐tionPEI-YANCHEN(陈佩燕)InstituteofGeophysics,StateSei... 展开更多
关键词 R/s method Hurst index EARTHQUAKE prediction NONLINEARITY
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Research on nonlinear R/S method and its application in earthquake prediction 被引量:1
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作者 王碧泉 黄汉明 +2 位作者 范洪顺 王春珍 陈佩燕 《Acta Seismologica Sinica(English Edition)》 CSCD 1995年第4期653-658,共6页
ResearchonnonlinearR/SmethodanditspplicationinearthquakepredictionBi-QuanWANG(王碧泉);Han-MingHUANG(黄汉明);Hong-S... ResearchonnonlinearR/SmethodanditspplicationinearthquakepredictionBi-QuanWANG(王碧泉);Han-MingHUANG(黄汉明);Hong-ShunFAN(范洪顺);Chuen... 展开更多
关键词 NONLINEAR theory FRACTAL DIMENsION EARTHQUAKE prediction R/s METHOD
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Spatial distribution prediction and benefits assessment of green manure in the Pinggu District,Beijing,based on the CLUE-S model 被引量:13
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作者 ZHANG Li-ping ZHANG Shi-wen +3 位作者 ZHOU Zhi-ming HOU Sen HUANG Yuan-fang CAO Wei-dong 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2016年第2期465-474,共10页
Green manure use in China has declined rapidly since the 1980 s with the extensive use of chemical fertilizers.The deterioration of field environments and the demand for green agricultural products have resulted in mo... Green manure use in China has declined rapidly since the 1980 s with the extensive use of chemical fertilizers.The deterioration of field environments and the demand for green agricultural products have resulted in more attention to green manure.Human intervention and policy-oriented behaviors likely have large impacts on promoting green manure planting.However,little information is available regarding on where,at what rates,and in which ways(i.e.,intercropping green manure in orchards or rotating green manure in cropland) to develop green manure and what benefits could be gained by incorporating green manure in fields at the county scale.This paper presents the conversion of land use and its effects at small region extent(CLUE-S) model,which is specifically developed for the simulation of land use changes originally,to predict spatial distribution of green manure in cropland and orchards in 2020 in Pinggu District located in Beijing,China.Four types of land use for planting or not planting green manure were classified and the future land use dynamics(mainly croplands and orchards) were considered in the prediction.Two scenarios were used to predict the spatial distribution of green manure based on data from 2011:The promotion of green manure planting in orchards(scenario 1) and the promotion of simultaneous green manure planting in orchards and croplands(scenario 2).The predictions were generally accurate based on the receiver operating characteristic(ROC) and Kappa indices,which validated the effectiveness of the CLUE-S model in the prediction.In addition,the spatial distribution of the green manure was acquired,which indicated that green manure mainly located in the orchards of the middle and southern regions of Dahuashan,the western and southern regions of Wangxinzhuang,the middle region of Shandongzhuang,the eastern region of Pinggu and the middle region of Xiagezhuang under scenario 1.Green manure planting under scenario 2 occurred in orchards in the middle region of Wangxinzhuang,and croplands in most regions of Daxingzhuang,southern Pinggu,northern Xiagezhuang and most of Mafang.The spatially explicit results allowed for the assessment of the benefits of these changes based on different economic and ecological indicators.The economic and ecological gains of scenarios 1 and 2 were 175691 900 and143000 300 CNY,respectively,which indicated that the first scenario was more beneficial for promoting the same area of green manure.These results can facilitate policies of promoting green manure and guide the extensive use of green manure in local agricultural production in suitable ways. 展开更多
关键词 绿肥种植 分布预测 空间分布 s模型 平谷区 效益评估 北京 土地利用变化
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