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LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR m-NEGATIVELY ASSOCIATED RANDOM VARIABLES 被引量:8
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作者 胡亦钧 明瑞星 杨文权 《Acta Mathematica Scientia》 SCIE CSCD 2007年第4期886-896,共11页
M-negatively associated random variables, which generalizes the classical one of negatively associated random variables and includes m-dependent sequences as its particular case, are introduced and studied. Large devi... M-negatively associated random variables, which generalizes the classical one of negatively associated random variables and includes m-dependent sequences as its particular case, are introduced and studied. Large deviation principles and moderate deviation upper bounds for stationary m-negatively associated random variables are proved. Kolmogorov-type and Marcinkiewicz-type strong laws of large numbers as well as the three series theorem for m-negatively associated random variables are also given. 展开更多
关键词 negatively associated random variables stationary sequence strong law of large numbers large deviations moderate deviations
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Sample Path Large Deviations for Independent Random Variables under Sub-Linear Expectations 被引量:1
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作者 Mingzhou XU 《Journal of Mathematical Research with Applications》 CSCD 2024年第4期541-550,共10页
In this work, the sample path large deviations for independent, identically distributed random variables under sub-linear expectations are established. The results obtained in sublinear expectation spaces extend the c... In this work, the sample path large deviations for independent, identically distributed random variables under sub-linear expectations are established. The results obtained in sublinear expectation spaces extend the corresponding ones in probability space. 展开更多
关键词 sample path large deviations independent random variables sub-linear expectation
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Variable Projection Order Adaptive Filtering Algorithm for Self-interference Cancellation in Airborne Radars
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作者 LI Haorui GAO Ying +1 位作者 GUO Xinyu OU Shifeng 《Transactions of Nanjing University of Aeronautics and Astronautics》 2025年第4期497-508,共12页
The adaptive filtering algorithm with a fixed projection order is unable to adjust its performance in response to changes in the external environment of airborne radars.To overcome this limitation,a new approach is in... The adaptive filtering algorithm with a fixed projection order is unable to adjust its performance in response to changes in the external environment of airborne radars.To overcome this limitation,a new approach is introduced,which is the variable projection order Ekblom norm-promoted adaptive algorithm(VPO-EPAA).The method begins by examining the mean squared deviation(MSD)of the EPAA,deriving a formula for its MSD.Next,it compares the MSD of EPAA at two different projection orders and selects the one that minimizes the MSD as the parameter for the current iteration.Furthermore,the algorithm’s computational complexity is analyzed theoretically.Simulation results from system identification and self-interference cancellation show that the proposed algorithm performs exceptionally well in airborne radar signal self-interference cancellation,even under various noise intensities and types of interference. 展开更多
关键词 adaptive filtering algorithm airborne radar variable projection order mean squared deviation self-interference cancellation
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Limit behaviors for dependent Bernoulli variables
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作者 MIAO Yu MA Huan-huan 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2020年第4期399-409,共11页
In this paper,we consider a class of dependent Bernoulli variables,which has the following form:for k≥m,P(Xk+1=1jFk)=Σm i=1θiXk+1i+θ0p,where m is a positive integer,Σmi=0θi=1,Fn=σ{X1,……,Xn},0<p<1.The co... In this paper,we consider a class of dependent Bernoulli variables,which has the following form:for k≥m,P(Xk+1=1jFk)=Σm i=1θiXk+1i+θ0p,where m is a positive integer,Σmi=0θi=1,Fn=σ{X1,……,Xn},0<p<1.The convergence rate of the strong law of large numbers and the moderate deviation principle for the model are established.Furthermore,we study some properties of parameter estimation for the model. 展开更多
关键词 strong law of large numbers moderate deviation Bernoulli variables MARTINGALE
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Mean Difference and Mean Deviation of Tukey Lambda Distribution
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作者 Giovanni Girone Antonella Massari +1 位作者 Fabio Manca Angela Maria D’Uggento 《Applied Mathematics》 2020年第8期771-778,共8页
The purpose of this paper is to broaden the knowledge of mean difference and,<span style="font-family:;" "=""> <span style="font-family:Verdana;"><span style="fon... The purpose of this paper is to broaden the knowledge of mean difference and,<span style="font-family:;" "=""> <span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">in particular, of an important distribution model known as Tukey lambda, which is generally used to choose a model to fit data.<span style="font-family:;" "=""> <span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">We have obtained compact formulas, which are not yet reported in literature, of mean deviation and mean difference related to the said distribution model.<span style="font-family:;" "=""> <span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">These results made it possible to analyze the relationships among variability indexes, namely standard deviation, mean deviation and mean difference, regarding Tukey lambda model. 展开更多
关键词 Mean Difference Mean deviation Tukey Lambda Distribution Variability Indexes’ Relationships
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Environmental variables shape the deviation of phylogenetic relatedness between terrestrial and aquatic herbaceous angiosperms across China
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作者 Yangyang Liu Hong Qian Yadong Zhou 《Journal of Plant Ecology》 2025年第3期129-143,共15页
Compared to terrestrial plants whose diversity is more directly influenced by climate,aquatic plant diversity is considered to be more dependent on water environments.Therefore,it could be predicted that the phylogene... Compared to terrestrial plants whose diversity is more directly influenced by climate,aquatic plant diversity is considered to be more dependent on water environments.Therefore,it could be predicted that the phylogenetic relatedness of terrestrial plants is more susceptible to climate filtering than that of aquatic plants.We compiled a comprehensive distribution dataset of herbaceous angiosperms in China,including both terrestrial and aquatic species.We compared the phylogenetic relatedness and its environmental correlation of the two groups,using the standardized effect size of phylogenetic diversity(PD_(ses))and the standardized effect size of mean phylogenetic distance(MPD_(ses)),which reflect shallow and deep evolutionary histories,respectively.We also use the deviation of PD_(ses)(ΔPD_(ses))and MPD_(ses)(ΔMPD_(ses))between terrestrial and aquatic plants to reflect differences in the phylogenetic relatedness between terrestrial and aquatic plants.Our results showed that the geographical patterns of PD_(ses)and MPD_(ses)between aquatic and terrestrial plants are roughly consistent.ΔPD_(ses)andΔMPD_(ses)between terrestrial and aquatic plants vary across the geographical scale and environmental gradient.Environmental variables(current climate,historical climate change and topography)explained more of the variation in PD_(ses)and MPD_(ses)of terrestrial plants than that of aquatic plants,with the current climate explaining more ofΔPD_(ses)andΔMPD_(ses)between terrestrial and aquatic plants.Our results reveal the differential impacts of large-scale environmental factors on the phylogenetic relatedness of terrestrial versus aquatic plant communities,providing a new perspective for understanding the ecological and evolutionary dynamics of these two distinct plant assemblages. 展开更多
关键词 TERRESTRIAL AQUATIC phylogenetic relatedness deviation environmental variables China
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PERIODIC SOLUTIONS FOR NEUTRAL LINARD EQUATION WITH A STATEMENT-DEPENDENT DEVIATION VARIABLE 被引量:6
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作者 Liu Xiping Jia Mei +1 位作者 Yang Liu Ge Weigao 《Annals of Differential Equations》 2005年第3期353-356,共4页
Using the theroy of topological degree, the paper studies the periodic solutions to a type of neutral Liénard equation with state-dependent deviation variable. A sufficient condition for the existence of periodic... Using the theroy of topological degree, the paper studies the periodic solutions to a type of neutral Liénard equation with state-dependent deviation variable. A sufficient condition for the existence of periodic solution is obtained. 展开更多
关键词 statement-dependent deviation variable neutral Liénard functional differential equation periodic solutions topological degree
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PERIODIC SOLUTION TO A CLASS OF SECOND ORDER NEUTRAL FUNCTIONAL DIFFERENTIAL EQUATION WITH A STATEMENT-DEPENDENT DEVIATION VARIABLE 被引量:4
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作者 Li Lei Zhou Zongfu 《Annals of Differential Equations》 2007年第3期280-287,共8页
We obtain sufficient conditions for class of second order neutral functional theorem of the coincidence degree. the existence of periodic solution to a differential equation, using continuation
关键词 periodic solution neutral functional differential equation statement-dependent deviation variable coincidence degree
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Sharp large deviation results for sums of independent random variables 被引量:1
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作者 FAN XieQuan GRAMA Ion LIU QuanSheng 《Science China Mathematics》 SCIE CSCD 2015年第9期1939-1958,共20页
We show sharp bounds for probabilities of large deviations for sums of independent random variables satisfying Bernstein's condition. One such bound is very close to the tail of the standard Gaussian law in certai... We show sharp bounds for probabilities of large deviations for sums of independent random variables satisfying Bernstein's condition. One such bound is very close to the tail of the standard Gaussian law in certain case; other bounds improve the inequalities of Bennett and Hoeffding by adding missing factors in the spirit of Talagrand(1995). We also complete Talagrand's inequality by giving a lower bound of the same form, leading to an equality. As a consequence, we obtain large deviation expansions similar to those of Cram′er(1938),Bahadur-Rao(1960) and Sakhanenko(1991). We also show that our bound can be used to improve a recent inequality of Pinelis(2014). 展开更多
关键词 Bernstein’s inequality sharp large deviations Cramér large deviations expansion of BahadurRao sums of independent random variabl
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Sharp large deviations for sums of bounded from above random variables
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作者 FAN XieQuan 《Science China Mathematics》 SCIE CSCD 2017年第12期2465-2480,共16页
We show large deviation expansions for sums of independent and bounded from above random variables. Our moderate deviation expansions are similar to those of Cram′er(1938), Bahadur and Ranga Rao(1960), and Sakhanenko... We show large deviation expansions for sums of independent and bounded from above random variables. Our moderate deviation expansions are similar to those of Cram′er(1938), Bahadur and Ranga Rao(1960), and Sakhanenko(1991). In particular, our results extend Talagrand's inequality from bounded random variables to random variables having finite(2 + δ)-th moments, where δ∈(0, 1]. As a consequence,we obtain an improvement of Hoeffding's inequality. Applications to linear regression, self-normalized large deviations and t-statistic are also discussed. 展开更多
关键词 sharp large deviations Cram′er large deviations Talagrand’s inequality Hoeffding’s inequality sums of independent random variables
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Moderate deviations principle for products of sums of random variables
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作者 MIAO Yu MU JianYong 《Science China Mathematics》 SCIE 2011年第4期769-784,共16页
Let(Xn)n≥1 be a sequence of independent identically distributed(i.i.d.) positive random variables with EX1 = μ,Var(X1) = σ2.In the present paper,we establish the moderate deviations principle for the products of pa... Let(Xn)n≥1 be a sequence of independent identically distributed(i.i.d.) positive random variables with EX1 = μ,Var(X1) = σ2.In the present paper,we establish the moderate deviations principle for the products of partial sums(πnk=1Sk/n!μn)1/(γbn√(2n))1where γ = σ/μ denotes the coefficient of variation and(bn) is the moderate deviations scale. 展开更多
关键词 moderate deviations principle products of sums independent identically distribution positive random variables
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基于变增益偏差耦合和自适应反推滑模的多电机同步控制 被引量:1
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作者 王磊 赵希梅 金鸿雁 《控制理论与应用》 北大核心 2025年第6期1248-1256,共9页
针对多电机系统存在跟踪性能差、同步精度低的问题,本文提出一种基于变增益偏差耦合(VGDC)和自适应反推滑模(ABSM)的同步控制方法.首先,由于受参数变化、外部扰动和负载改变等不确定因素影响而导致单电机跟踪性能差的问题,设计ABSM控制... 针对多电机系统存在跟踪性能差、同步精度低的问题,本文提出一种基于变增益偏差耦合(VGDC)和自适应反推滑模(ABSM)的同步控制方法.首先,由于受参数变化、外部扰动和负载改变等不确定因素影响而导致单电机跟踪性能差的问题,设计ABSM控制算法,并构建李雅普诺夫函数验证该方法的稳定性和收敛性.然后,为了克服固定耦合增益不能随负载或扰动发生改变,从而降低多电机同步控制性能的缺点,利用模型参考辨识法(MRIM)获得电机的实时转动惯量,将其发送到速度补偿器获得可变耦合增益,以此改进偏差耦合控制结构提高多电机系统同步性能.最后,根据实验验证所提出方法可以改善控制系统的跟踪性能,且可以提高多电机同步控制精度,具有重要的实际应用价值. 展开更多
关键词 多电机同步控制 偏差耦合 变增益 速度补偿 自适应反推滑模控制
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收缩压昼夜变异率联合正常RR间期标准差对冠心病诊断价值的临床研究
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作者 周启保 罗潇 +4 位作者 陈玲 曹俊达 李菊香 徐劲松 苏海 《中国全科医学》 北大核心 2025年第30期3760-3765,共6页
背景 目前确诊冠心病的主要方法为冠状动脉增强CT及冠状动脉造影检查,其中冠状动脉增强CT检查由于准确性欠佳,部分患者心率过快不能进行导致其临床应用受限,而作为“金标准”的冠状动脉造影检查由于有创性,在基层医疗单位难以大范围普... 背景 目前确诊冠心病的主要方法为冠状动脉增强CT及冠状动脉造影检查,其中冠状动脉增强CT检查由于准确性欠佳,部分患者心率过快不能进行导致其临床应用受限,而作为“金标准”的冠状动脉造影检查由于有创性,在基层医疗单位难以大范围普及同样使其推广受阻。目的 探索收缩压昼夜变异率联合SDNN对冠心病的诊断价值,以期为评估冠心病诊断提供无创方法学参考。方法 选取2018—2022年就诊于九江市第一人民医院的246例通过冠状动脉造影检查明确诊断为冠心病且在行冠状动脉造影检查前具有动态心电图检查结果以及病房内昼夜血压监测记录的患者作为研究对象,分为冠心病组与非冠心病组,比较两组对象的一般基线资料;将冠心病诊断与否作为观察终点,分析纳入观察的各项参数与终点事件的相关性并探索可能与终点事件相关的影响因素;绘制收缩压昼夜变异率联合正常窦性心搏间期标准差(SDNN)诊断冠心病的ROC曲线,并进行分析。结果 冠心病组与非冠心病组基线资料的比较结果显示,年龄、SDNN、收缩压昼夜变异率之间的差异有统计学意义(P<0.05)。相关性分析结果显示,年龄和收缩压昼夜变异率与冠心病诊断呈正相关(P<0.05),左心室舒张末期内径(LVD)和SDNN与冠心病诊断呈负相关(P<0.05)。二元Logistic回归分析显示,年龄、LVD、左心室舒张末容积(EDV)、每分输出量(CO)、SDNN、收缩压昼夜变异率是冠心病诊断的影响因素(P<0.05)。SDNN诊断冠心病的AUC为0.690(95%CI=0.620~0.760),灵敏度和特异度分别为0.753和0.615,对应的最佳截断值为128.5。收缩压昼夜变异率诊断冠心病的AUC为0.908(95%CI=0.869~0.948),灵敏度和特异度分别为0.847和0.896,对应的最佳截断值为14.61%。收缩压昼夜变异率联合SDNN诊断冠心病的AUC为0.914(95%CI=0.875~0.953),灵敏度和特异度分别为0.827和0.917,对应的最佳截断值为0.721。结论 年龄、LVD、EDV、CO、SDNN、收缩压昼夜变异率是冠心病诊断的影响因素。收缩压昼夜变异率联合SDNN对于冠心病的诊断具有较好的临床应用价值。 展开更多
关键词 收缩压昼夜变异率 RR间期标准差 冠心病 诊断价值
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基于惩罚型变权模型的京津冀城市生态安全评估及障碍因素分析
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作者 张学儒 罗雨田 +2 位作者 宋伟 阳大智 张旭阳 《地理研究》 北大核心 2025年第12期3287-3303,共17页
生态系统评估对经济社会的可持续发展至关重要,但现有的生态安全指标赋权方法往往忽视了时间效应及“薄弱环节”的影响,且对区域内城市生态安全差异的障碍因素分析尚不够深入。为弥补这些不足,本研究引入了一种基于惩罚机制的变量加权模... 生态系统评估对经济社会的可持续发展至关重要,但现有的生态安全指标赋权方法往往忽视了时间效应及“薄弱环节”的影响,且对区域内城市生态安全差异的障碍因素分析尚不够深入。为弥补这些不足,本研究引入了一种基于惩罚机制的变量加权模型,将其与PSR模型结合评价城市生态安全,进一步结合标准差椭圆模型及障碍度模型,系统分析了2006-2020年京津冀地区的生态安全时空特征与障碍因素。结果表明:(1)在2006-2020年间,京津冀城市的生态安全指数在波动中持续增长,年均增幅达到4.84%;(2)在城市生态安全子系统的整体贡献顺序为响应(占比45.83%)>状态(占比33.53%)>压力(占比20.64%),高安全等级城市表现出更强烈的子系统非均衡性。(3)污水处理能力不足、科技支出占比偏低和文化资源配置问题是长期制约京津冀城市生态安全发展的关键障碍因子。 展开更多
关键词 城市生态安全 变权模型 障碍度模型 京津冀 PSR框架 标准差椭圆
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某低压长距离配电线路保护措施对比分析
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作者 佘奇 汤燕 《建筑电气》 2025年第5期30-34,共5页
结合实际工程项目,针对长距离供配电设计,对比分析电动机类负荷直接启动、星三角启动、软启动及变频启动等方式下启动电流对保护开关整定、灵敏度校验的影响,同时结合不同启动方式进行工程造价对比分析,提出相应的技术措施。
关键词 长距离 直接启动 星三角启动 软启动 变频启动 启动电流 电压偏差 工程造价
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土工格室加筋风化千枚岩填料应力应变响应 被引量:1
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作者 何新平 朱元林 +2 位作者 刘瑾 兰虎 刘娜 《路基工程》 2025年第2期63-69,共7页
采用大型三轴试验,测试对比风化千枚岩与常规满足规范使用要求路堤填料碎石土的应力-应变曲线,分析两者的差异性;基于土工格室加筋土应力-应变响应计算模型和参数敏感性,分析风化千枚岩填料的邓肯-张模型弹性常数、强度参数和格室切线... 采用大型三轴试验,测试对比风化千枚岩与常规满足规范使用要求路堤填料碎石土的应力-应变曲线,分析两者的差异性;基于土工格室加筋土应力-应变响应计算模型和参数敏感性,分析风化千枚岩填料的邓肯-张模型弹性常数、强度参数和格室切线模量对于格室加筋风化千枚岩强度的影响。研究表明:格室加筋风化千枚岩的峰值偏差应力可超过碎石,加筋土的等效黏聚力随着弹性常数k值减小、填土的破坏比R_(f )增加、内摩擦角φ增加、格室条带刚度M_(t )的增加而增大。 展开更多
关键词 土工格室 填料 千枚岩 三轴试验 峰值偏差 差异性 等效黏聚力 路用性能
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Some Results on Probabilities of Moderate Deviations
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作者 Deli Li Yu Miao Yongcheng Qi 《Acta Mathematica Sinica,English Series》 2025年第12期2855-2876,共22页
Let{X,X_(n);n≥1}be a sequence of i.i.d.non-degenerate real-valued random variables with EX^(2)<∞.Let S_(n)=∑_(i=1)^(n)X_(i),n≥1.Let g(·):[0,∞)→[0,∞)be a nondecreasing regularly varying function with in... Let{X,X_(n);n≥1}be a sequence of i.i.d.non-degenerate real-valued random variables with EX^(2)<∞.Let S_(n)=∑_(i=1)^(n)X_(i),n≥1.Let g(·):[0,∞)→[0,∞)be a nondecreasing regularly varying function with indexρ≥0 and limt→∞g(t)=∞.Letμ=EX andσ^(2)=E(X−μ)^(2).In this paper,on the scale g(log n),we obtain precise asymptotic estimates for the probabilities of moderate deviations of the form log P(S_(n)−nμ>x√ng(log n)),log P(S_(n)−nμ<−x√ng(log n)),and log P(|S_(n)−nμ|>x√ng(log n))for all x>0.Unlike those known results in the literature,the moderate deviation results established in this paper depend on both the variance and the asymptotic behavior of the tail distribution of X. 展开更多
关键词 Large deviations moderate deviations second moment condition sums of i.i.d.random variables
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风扇/压气机进口可变弯度导叶特性模型研究
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作者 杨楠山 费腾 +1 位作者 季路成 周玲 《工程热物理学报》 北大核心 2025年第5期1500-1511,共12页
在风扇/压气机通流设计过程当中,叶栅经验模型是其核心支撑。为得到二维进口可变弯度导叶叶栅的损失及落后角模型,基于NACA 65-010叶型的厚度分布生成了一系列具有不同几何参数的平面导叶叶栅,并在来流马赫数为0.4工况下对叶栅进行系统... 在风扇/压气机通流设计过程当中,叶栅经验模型是其核心支撑。为得到二维进口可变弯度导叶叶栅的损失及落后角模型,基于NACA 65-010叶型的厚度分布生成了一系列具有不同几何参数的平面导叶叶栅,并在来流马赫数为0.4工况下对叶栅进行系统地数值仿真计算。基于该数值结果,考虑稠度、最大相对厚度和后叶弯角等叶栅参数的影响,首先拟合给出了导叶叶栅在设计点的损失及落后角模型。之后,针对所提出的损失及落后角模型,进一步引入了来流攻角和后叶转角影响参数,对导叶叶栅在非设计点的预测特性进行了修正。最后,通过对新的VIGV叶栅进行数值验证,发现所提出的损失及落后角模型预测结果与数值仿真结果具有较高的吻合度,表明该模型具有工程实用价值。 展开更多
关键词 压气机 进口可变弯度导叶 数值计算 损失模型 落后角模型
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2型糖尿病患者心率变异性与脑梗死的相关性研究
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作者 徐君 张劼 《中国全科医学》 北大核心 2025年第35期4409-4413,共5页
背景心率变异性(HRV)与脑梗死发生相关。然而,在2型糖尿病患者中,关于HRV与脑梗死关系的研究尚少。目的探讨2型糖尿病患者HRV与脑梗死的关系。方法选取2020年1月—2022年8月在宁波市第二医院住院的577例2型糖尿病患者,根据患者有无脑梗... 背景心率变异性(HRV)与脑梗死发生相关。然而,在2型糖尿病患者中,关于HRV与脑梗死关系的研究尚少。目的探讨2型糖尿病患者HRV与脑梗死的关系。方法选取2020年1月—2022年8月在宁波市第二医院住院的577例2型糖尿病患者,根据患者有无脑梗死分为脑梗死组和无脑梗死组。收集患者一般资料、实验室检查结果。患者均进行24 h动态心电图监测,HRV参数包括全部正常窦性心搏间期的标准差(SDNN)、相邻RR间期之差的均方根值(rMSSD)和相邻RR间期相差>50 ms的数量占总心搏数的百分比(PNN50)。采用多因素Logistic回归分析探究HRV与脑梗死的关系。依据HRV参数中SDNN水平将患者分为SDNN减低组(SDNN<100 ms)与SDNN正常组(SDNN≥100 ms),并分析其与脑梗死的关系。结果共纳入577例2型糖尿病患者,脑梗死组287例,无脑梗死组290例。多因素Logistic回归分析结果显示,SDNN水平是2型糖尿病患者发生脑梗死的独立影响因素(OR=0.970,95%CI=0.961~0.979,P<0.05)。SDNN减低组264例,SDNN正常组313例。多因素Logistic回归分析结果显示,SDNN减低组患者发生脑梗死风险较正常组高(OR=4.164,95%CI=2.769~6.262,P<0.05)。结论2型糖尿病患者中HRV参数减低与脑梗死相关,随着SDNN减低,患者发生脑梗死的风险增高。 展开更多
关键词 2型糖尿病 脑梗死 心率变异性 全部正常窦性心搏间期的标准差
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