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Heart rate-adjusted PR as a prognostic marker of long-term ventricular arrhythmias and cardiac death in ICD/CRT-D recipients 预览
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作者 Yu-Qiu LI Shuang ZHAO +8 位作者 Ke-Ping CHEN Yang-Gang SU Wei HUA Si-Lin CHEN Zhao-Guang LIANG Wei XU Yan DAI Xiao-Han FAN Shu ZHANG 《老年心脏病学杂志:英文版》 SCIE CAS CSCD 2019年第3期259-264,共6页
Objective To evaluate the PR to RR interval ratio (PR/RR,heart rate-adjusted PR) as a prognostic marker for long-term ventricular arrhythmias and cardiac death in patients with implantable cardioverter defibrillator (... Objective To evaluate the PR to RR interval ratio (PR/RR,heart rate-adjusted PR) as a prognostic marker for long-term ventricular arrhythmias and cardiac death in patients with implantable cardioverter defibrillator (ICDs) and cardiac resynchronization therapy with defibrillators (CRT-D).Methods We retrospectively analyzed data from 428 patients who had an ICD/CRT-D equipped with home monitoring.Baseline PR and RR interval data prior to ICD/CRT-D implantation were collected from standard 12-lead electrocardiograph,and the PR/RR was calculated.The primary endpoint was appropriate ICD/CRT-D treatment of ventricular arrhythmias (VAs),and the secondary endpoint was cardiac death.Results During a mean follow-up period of 38.8 ± 10.6 months,197 patients (46%) experienced VAs,and 47 patients (11%) experienced cardiac death.The overall PR interval was 160 ± 40 ms,and the RR interval was 866 ± 124 ms.Based on the receiver operating characteristic curve,a cut-off value of 18.5% for the PR/RR was identified to predict VAs.A PR/RR ≥ 18.5% was associated with an increased risk of VAs [hazard ratio (HR)= 2.243,95% confidence interval (CI)= 1.665–3.022,P < 0.001) and cardiac death (HR = 2.358,95%CI = 1.240–4.483,P = 0.009) in an unadjusted analysis.After adjustment in a multivariate Cox model,the relationship remained significant among PR/RR ≥ 18.5%,VAs (HR = 2.230,95%CI = 1.555–2.825,P < 0.001) and cardiac death (HR = 2.105,95%CI = 1.101–4.025,P = 0.024.Conclusions A PR/RR ≥ 18.5% at baseline can serve as a predictor of future VAs and cardiac death in ICD/CRT-D recipients. 展开更多
关键词 IMPLANTABLE cardioverter DEFIBRILLATOR PR INTERVAL RR INTERVAL Ventricular ARRHYTHMIAS
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Association between ventricular repolarization variables and cardiac diastolic function: A cross-sectional study of a healthy Chinese population 预览
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作者 Zhi-Dan Li Xiao-Juan Bai +3 位作者 Lu-Lu Han Wen Han Xue-Feng Sun Xiang- Mei Chen 《世界临床病例杂志》 2019年第8期940-950,共11页
BACKGROUND Diastolic electromechanical couple, a well-described phenomenon in symptomatic heart failure, has not been well studied in healthy people. We hypothesized that ventricular repolarization variables, such as ... BACKGROUND Diastolic electromechanical couple, a well-described phenomenon in symptomatic heart failure, has not been well studied in healthy people. We hypothesized that ventricular repolarization variables, such as the QT interval, Tpeak-to-Tend (Tpe) interval and Tpe/QT ratio, are associated with cardiac diastolic function in the healthy Chinese population. AIM To assess the relationship between ventricular repolarization variables and cardiac diastolic function in apparently healthy Chinese individuals. METHODS This was a community-based cross-sectional study conducted in Shenyang, China. A total of 414 healthy subjects aged 35-91 years were enrolled. All subjects underwent standard 12-lead electrocardiography (ECG) and comprehensive echocardiography. ECG enabled the measurement of QT and Tpe intervals and Tpe/QT ratio. echocardiographic parameters, such as the ratio of mitral early diastolic inflow velocity (E) and late diastolic inflow velocity (A), E-wave deceleration time, left atrial volume (LAV) and LAV index, were measured to assess diastolic function. E/A < 0.75 was considered to indicate reduced diastolic function. ECG and echocardiography results were analyzed separately and in a blinded fashion. Correlation and regression analyses were applied to determine associations. RESULTS Ventricular repolarization variables, such as the QTc interval (393.59 ± 26.74 vs 403.86 ± 33.56;P < 0.001), Tpe interval (72.68 ± 12.41 vs 77.26 ± 17.86;P < 0.01), Tpec interval (76.36 ± 13.53 vs 83.32 ± 21.25;P < 0.001) and Tpe/QT ratio (0.19 ± 0.03 vs 0.20 ± 0.04;P < 0.01), were significantly different between the normal diastolic function group and the reduced diastolic function group. Significant associations were found between repolarization variables and diastolic function. After adjusting for all other possible confounders, the QTc and Tpec intervals were significantly associated with the E/A ratio (P = 0.008;P = 0.010). In men, the QTc interval was associated with abnormal diastolic function, and compared to 展开更多
关键词 QT INTERVAL Tpeak-to-Tend INTERVAL DIASTOLIC DYSFUNCTION VENTRICULAR REPOLARIZATION ELECTROCARDIOGRAPHY
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宫颈锥切术后行子宫全切术的间隔时间对手术效果的影响分析 预览
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作者 赵福英 张洪炜 +2 位作者 贾佳 郭玉娥 高智达 《医学信息》 2019年第13期100-101,共2页
目的探讨宫颈锥切术后再行子宫全切术的手术间隔时间对手术并发症的影响。方法回顾性分析2012年1月~2018年10月银川市妇幼保健院宫颈锥切术后行子宫全切术76例患者临床资料,按照手术间隔时间不同分为三组,宫颈锥切术后72h内行子宫全切术... 目的探讨宫颈锥切术后再行子宫全切术的手术间隔时间对手术并发症的影响。方法回顾性分析2012年1月~2018年10月银川市妇幼保健院宫颈锥切术后行子宫全切术76例患者临床资料,按照手术间隔时间不同分为三组,宫颈锥切术后72h内行子宫全切术的22例患者设为A组;宫颈锥切术后72h~4周行子宫全切术的患者25例设为B组;宫颈锥切术后4周以上行子宫全切术的29例患者设为C组,比较三组之间术中出血、手术时间、术后体温、手术并发症。结果三组之间术中出血、手术时间比较,差异无统计学意义(P>0.05),而三组之间术后体温≥38℃的天数比较,差异有统计学意义(P<0.05),且B组术后体温≥38℃的天数多于A组与C组,差异有统计学意义(P<0.05)。B组并发症发生率为44.00%,分别高于A组的13.64%和C组的13.79%,差异有统计学意义(P<0.05)。结论宫颈锥切术后72h~4周行子宫全切术,术后并发症发生率高,术后感染率高,应避免在此时间段手术。 展开更多
关键词 宫颈锥切术后 子宫全切术 间隔时间 并发症
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A Direct Method of Interval Banzhaf Values of Interval Cooperative Games
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作者 Kairong Liang Dengfeng Li 《系统科学与系统工程学报:英文版》 SCIE EI CSCD 2019年第3期382-391,共10页
The goal of this paper is to develop a direct method for computing interval Banzhaf values for a class of interval cooperative games.In this method,it is proven that the Banzhaf values of the associated cooperative ga... The goal of this paper is to develop a direct method for computing interval Banzhaf values for a class of interval cooperative games.In this method,it is proven that the Banzhaf values of the associated cooperative games of interval cooperative games are monotonic and non-decreasing functions of coalitions,payoffs under weaker coalition monotonicity-like conditions.So the interval Banzhaf values can be explicitly obtained through using only the lower and upper bounds of the coalitions'interval payoffs,respectively.The proposed method does not employ interval subtractions and hereby can effectively avoid the irrational issues such as irreversibility and uncertainty enlargement.We prove some important and desirable properties of the interval Banzhaf values and illustrate the applicability and validity of the proposed method with a numerical example. 展开更多
关键词 INTERVAL COOPERATIVE GAME Banzhaf VALUE group DECISION COOPERATIVE GAME
Effects of High Intensity Interval Exercise on Blood Pressure 预览
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作者 Xiaoyu Wei 《校园英语》 2019年第18期255-256,共2页
This paper reviews the effect of high intensity interval exercise on blood pressure and discussed the mechanism of decreasing blood pressure.
关键词 High INTENSITY INTERVAL EXERCISE BLOOD PRESSURE Effect
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A Hybrid Procedure for Finding Real Points on a Real Algebraic Set
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作者 WANG Yu XIA Bican 《系统科学与复杂性学报:英文版》 SCIE EI CSCD 2019年第1期185-204,共20页
Motivated by the idea of Shen, et al.’s work, which proposed a hybrid procedure for real root isolation of polynomial equations based on homotopy continuation methods and interval analysis,this paper presents a hybri... Motivated by the idea of Shen, et al.’s work, which proposed a hybrid procedure for real root isolation of polynomial equations based on homotopy continuation methods and interval analysis,this paper presents a hybrid procedure to compute sample points on each connected component of a real algebraic set by combining a special homotopy method and interval analysis with a better estimate on initial intervals. For a real algebraic set given by a polynomial system, the new method first constructs a square polynomial system which represents the sample points, and then solve this system by a special homotopy continuation method introduced recently by Wang, et al.(2017). For each root returned by the homotopy continuation method, which is a complex approximation of some(complex/real) root of the polynomial system, interval analysis is used to verify whether it is an approximation of a real root and finally get real points on the given real algebraic set. A new estimate on initial intervals is presented which helps compute smaller initial intervals before performing interval iteration and thus saves computation. Experiments show that the new method works pretty well on tested examples. 展开更多
关键词 HOMOTOPY CONTINUATION interval ARITHMETIC POLYNOMIAL system REAL VARIETY
农业生产和农户经营的适度规模区间:目标差异及形成机制——来自重庆柑橘产业的验证 预览
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作者 曾令果 王钊 《西部论坛》 CSSCI 北大核心 2019年第2期64-72,共9页
农业生产的宏观目标是产量的提高,而农户进行农业经营的微观目标是收入的增加,二者目标既有相关性又有不同的内涵,基于此,文章考察了农业生产和农户经营的适度规模区间及形成机制。以重庆柑橘产业为例,利用275份有效调查问卷,采用数据... 农业生产的宏观目标是产量的提高,而农户进行农业经营的微观目标是收入的增加,二者目标既有相关性又有不同的内涵,基于此,文章考察了农业生产和农户经营的适度规模区间及形成机制。以重庆柑橘产业为例,利用275份有效调查问卷,采用数据包络分析法对柑橘种植的多个规模区间进行生产效率分析,结果显示:柑橘种植存在多个有效决策区间,即这些有效区间的投入产出处于均衡状态;运用超效率测算发现,由于农业生产和农户经营的目标差异,二者关于适度规模的区间也具有明显差异性;从产业管理者关心产量的角度考虑,柑橘生产的适度规模经营区间为10~11. 33公顷;从农户关心收入的角度考虑,柑橘经营的适度规模区间为1. 33~1. 87公顷。 展开更多
关键词 农业生产 农户经营 适度规模 区间 柑橘
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基于二参数寻优设计点的混合结构可靠性分析算法 预览
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作者 邱涛 张建国 +2 位作者 邱继伟 魏娟 游令非 《兵工学报》 EI CAS CSCD 北大核心 2019年第4期865-873,共9页
针对机械结构中既含随机变量又含区间变量的混合可靠性问题,提出一种基于二参数的混合可靠性分析算法。区间变量使可靠性分析问题变为双层优化问题,为降低双层优化模型对计算效率的影响,将其解耦为概率分析和区间分析高效循环序列迭代模... 针对机械结构中既含随机变量又含区间变量的混合可靠性问题,提出一种基于二参数的混合可靠性分析算法。区间变量使可靠性分析问题变为双层优化问题,为降低双层优化模型对计算效率的影响,将其解耦为概率分析和区间分析高效循环序列迭代模型;在概率分析时,引入两个调整参数,分别控制搜索步长和搜索方向,以实现寻优设计点、保证收敛的稳定性及搜索效率;在区间分析时,将区间分析问题转化为方便求解的二次规划问题,并结合梯度投影法搜索区间最优点;通过两个案例分析,对所提算法的计算精度和效率进行验证。结果表明:该算法与蒙特卡洛抽样法相比,计算的最大失效概率相对误差均在5%以内,且函数调用次数在1000次以内即可达到收敛;当功能函数非线性程度较高时,该算法同样具有较高的计算精度、效率及收敛稳定性。 展开更多
关键词 结构可靠性 混合不确定性 序列迭代 寻优设计点 调整参数 区间
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Parameter Optimization of Interval Type-2 Fuzzy Neural Networks Based on PSO and BBBC Methods 预览
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作者 Jiajun Wang Tufan Kumbasar 《自动化学报:英文版》 CSCD 2019年第1期247-257,共11页
Interval type-2 fuzzy neural networks(IT2FNNs)can be seen as the hybridization of interval type-2 fuzzy systems(IT2FSs) and neural networks(NNs). Thus, they naturally inherit the merits of both IT2 FSs and NNs. Althou... Interval type-2 fuzzy neural networks(IT2FNNs)can be seen as the hybridization of interval type-2 fuzzy systems(IT2FSs) and neural networks(NNs). Thus, they naturally inherit the merits of both IT2 FSs and NNs. Although IT2 FNNs have more advantages in processing uncertain, incomplete, or imprecise information compared to their type-1 counterparts, a large number of parameters need to be tuned in the IT2 FNNs,which increases the difficulties of their design. In this paper,big bang-big crunch(BBBC) optimization and particle swarm optimization(PSO) are applied in the parameter optimization for Takagi-Sugeno-Kang(TSK) type IT2 FNNs. The employment of the BBBC and PSO strategies can eliminate the need of backpropagation computation. The computing problem is converted to a simple feed-forward IT2 FNNs learning. The adoption of the BBBC or the PSO will not only simplify the design of the IT2 FNNs, but will also increase identification accuracy when compared with present methods. The proposed optimization based strategies are tested with three types of interval type-2 fuzzy membership functions(IT2FMFs) and deployed on three typical identification models. Simulation results certify the effectiveness of the proposed parameter optimization methods for the IT2 FNNs. 展开更多
关键词 BIG bang-big crunch (BBBC) INTERVAL type-2 fuzzy NEURAL networks (IT2FNNs) parameter OPTIMIZATION particle SWARM OPTIMIZATION (PSO)
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A PCA-Based Approach for Structural Dynamics Model Updating with Interval Uncertainty
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作者 Xueqian Chen Zhanpeng Shen Xin'en Liu 《固体力学学报:英文版》 SCIE EI CSCD 2019年第1期105-119,共15页
Uncertainty widely exists in engineering structures,making it necessary to update the finite element(FE)modeling with uncertainty.An updating approach for the FE model of structural dynamics with interval uncertain pa... Uncertainty widely exists in engineering structures,making it necessary to update the finite element(FE)modeling with uncertainty.An updating approach for the FE model of structural dynamics with interval uncertain parameters is proposed in this work.Firstly,the correlations between the updating parameters and the output qualities of interest are uncorrelated by the principal component analysis(PCA),and the massive samples of major principal components are obtained using the Monte Carlo simulation.Then,the massive samples of updating parameters and output qualities are obtained by reversing transformation in the PCA,and the new samples of updating parameters are re-chosen by combining the massive samples with the experimental intervals of the qualities of interest.Next,the 95%CI of the updating parameters is estimated by the nonparametrie kernel density estimation approach,which are regarded as the intervals of updating parameters.Lastly,the proposed approach is validated in simple rectangular plates and the transport mirror system.The updating results evidently demonstrate the feasibility and reliability of the proposed approach. 展开更多
关键词 PCA-based APPROACH INTERVAL uncertainty Model updating KERNEL density estimation
区间删失下恒定应力部分加速寿命试验的统计分析(英文) 预览
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作者 龙兵 张忠占 《数学季刊:英文版》 2019年第1期1-13,共13页
In this paper, a statistical analysis method is proposed to research life characteristics of products based on the partially accelerated life test. We discuss the statistical analysis for constant-stress partially acc... In this paper, a statistical analysis method is proposed to research life characteristics of products based on the partially accelerated life test. We discuss the statistical analysis for constant-stress partially accelerated life tests with Lomax distribution based on interval censored samples. The EM algorithm is used to obtain the maximum likelihood estimations(MLEs) and interval estimations for the shape parameter and acceleration factor.The average relative errors(AREs), mean square errors(MSEs), the confidence intervals for the parameters, and the influence of the sample size are discussed. The results show that the AREs and MSEs of the MLEs decrease with the increase of sample size. Finally, a simulation sample is used to estimate the reliability under different stress levels. 展开更多
关键词 INTERVAL censored samples PARTIALLY ACCELERATED life test ACCELERATED factor EM algorithm FISHER information matrix
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Factors influencing the pumpability of unclassified tailings slurry and its interval division 预览
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作者 Peng Li Yun-bing Hou Mei-feng Cai 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第4期417-429,共13页
Tailings consolidation and discharging technology is currently a popular means for disposing tailings in China.In this study,we describe a laboratory investigation of the unclassified tailings slurry from an iron mine... Tailings consolidation and discharging technology is currently a popular means for disposing tailings in China.In this study,we describe a laboratory investigation of the unclassified tailings slurry from an iron mine and analyze the influence of the concentration,amount of consolidation agent,and types of consolidation agent on the pumpability in terms of the slump,slump flow,and bleeding rate of the slurry.The results indicate that an increase in concentration leads to a pronounced decrease in the magnitude of the slump,slump flow,and the bleeding rate.Compared with the consolidation agents P.O42.5 and P.S.A32.5,the new consolidation agent offers substantial advantages in promoting the pumping performance of the slurry.The concentration more strongly affects the slump,slump flow,and the bleeding rate of the slurry than does the amount of the consolidation agent.We also constructed the pumpability interval of the slurry on the basis of the slump and bleeding rate and accordingly determined the proportioning parameters of the slurry with a concentration of 75wt%to 79wt%and with a consolidation agent concentration of 2wt%.In addition,we discussed the pumpability mechanism of the slurry. 展开更多
关键词 TAILINGS CONSOLIDATION and DISCHARGING technology unclassified TAILINGS new CONSOLIDATION agent PUMPABILITY INTERVAL PUMPABILITY mechanism
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Interval Motion Accuracy Reliability Analysis of Manipulators Based on Chebyshev Inclusion Polynomial 预览
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作者 Juan Wei Jianguo Zhang Xiaosong Du 《哈尔滨工业大学学报:英文版》 EI CAS 2019年第2期32-40,共9页
Motion accuracy of space manipulators has direct effects on the ability of the systems to perform specified tasks.However,some design variables are inherently interval parameters due to uncertainties in geometric stru... Motion accuracy of space manipulators has direct effects on the ability of the systems to perform specified tasks.However,some design variables are inherently interval parameters due to uncertainties in geometric structures,material properties,and so on.This paper presents Chebyshev inclusion function(CIF)for approximating the dynamic responses function of parametrically excited systems.Motion accuracy reliability(MAR)of space manipulators was evaluated based on mechanism reliability analysis methods and interval uncertainty model.To illustrate the accuracy of the proposed method,a two-link manipulator with interval parameters was demonstrated.The results showed that the proposed method required much fewer samples to obtain more accurate reliability compared with the traditional Monte Carlo simulation(MCS).Finally,the sensitivity analysis was performed to facilitate the optimization design by using global sensitivity analysis. 展开更多
关键词 space MANIPULATOR motion accuracy reliability(MAR) INTERVAL theory CHEBYSHEV INCLUSION function(CIF)
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The time model for event processing in internet of things
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作者 Chunjie ZHOU Xiaoling WANG +2 位作者 Zhiwang ZHANG Zhenxing ZHANG Haiping QU 《中国计算机科学前沿:英文版》 SCIE EI CSCD 2019年第3期471-488,共18页
The time management model for event processing in internet of things has a special and important requirement. Many events in real world applications are long-lasting events which have different time granularity with o... The time management model for event processing in internet of things has a special and important requirement. Many events in real world applications are long-lasting events which have different time granularity with order or out-of-order. The temporal relationships among those events are often complex. An important issue of complex event processing is to extract patterns from event streams to support decision making in real-time. However, current time management model does not consider the unified solution about time granularity, time interval, time disorder, and the difference between workday calendar systems in different organizations. In this work, we analyze the preliminaries of temporal semantics of events. A tree-plan model of out-of-order durable events is proposed. A hybrid solution is correspondingly introduced. A case study is illustrated to explain the time constraints and the time optimization. Extensive experi? mental studies demonstrate the efficiency of our approach. 展开更多
关键词 TIME model EVENT processing internet of THINGS TIME INTERVAL TIME DISORDER
Interval optimal power flow applied to distribution networks under uncertainty of loads and renewable resources 预览
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作者 Pengwei CHEN Xiangning XIAO Xuhui WANG 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第1期139-150,共12页
Optimal power flow(OPF) has been used for energy dispatching in active distribution networks.To satisfy constraints fully and achieve strict operational bounds under the uncertainties from loads and sources, this pape... Optimal power flow(OPF) has been used for energy dispatching in active distribution networks.To satisfy constraints fully and achieve strict operational bounds under the uncertainties from loads and sources, this paper derives an interval optimal power flow(I-OPF)method employing affine arithmetic and interval Taylor expansion.An enhanced I-OPF method based on successive linear approximation and second-order cone programming is developed to improve solution accuracy.The proposed methods are benchmarked against Monte Carlo simulation(MCS) and stochastic OPF.Tests on a modified IEEE 33-bus system and a real 113-bus distribution network validate the effectiveness and applicability of the proposed methods. 展开更多
关键词 Active distribution network Optimal power flow INTERVAL UNCERTAINTY AFFINE ARITHMETIC SECOND-ORDER cone programming
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球囊扩张食管闭锁术后吻合口狭窄的间隔时间
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作者 张晓 程艳波 史长松 《医药论坛杂志》 2019年第4期29-30,共2页
目的探究食管闭锁术后吻合口狭窄行球囊扩张术的适宜间隔时间。方法回顾性分析2016年04月—2018年2月的59例次食管闭锁术后吻合口狭窄的患儿行球囊扩张术的间隔时间及出现吞咽困难等症状,根据间隔时间将数据分为4组,A(1周)、B(2周)、C(3... 目的探究食管闭锁术后吻合口狭窄行球囊扩张术的适宜间隔时间。方法回顾性分析2016年04月—2018年2月的59例次食管闭锁术后吻合口狭窄的患儿行球囊扩张术的间隔时间及出现吞咽困难等症状,根据间隔时间将数据分为4组,A(1周)、B(2周)、C(3周)、D(4周),计算四组中吞咽困难等症状出现的发生率,应用χ~2检验进行统计学分析。结果①间隔1~3周时吞咽困难等的发生率发生率均较低,差异无统计学意义(P>0.05)。②间隔4周时较间隔1~3周的吞咽困难等发生率明显增高,差异有明显统计学意义(P<0.05)。结论两次扩张间隔适宜时间1-3周。 展开更多
关键词 间隔时间 先天性食管狭闭锁 吻合口狭窄 球囊扩张术 儿童
Approach for air-to-air confrontment based on uncertain interval information conditions 预览
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作者 LI Qiuni YANG Rennong +1 位作者 FENG Chao LIU Zongcheng 《系统工程与电子技术:英文版》 SCIE EI CSCD 2019年第1期100-109,共10页
Model combat information conditions are always uncertain and varied, the uncertain interval theory is therefore introduced into the research of multiple fighters suppressing the integrated air defense system (IADS) pr... Model combat information conditions are always uncertain and varied, the uncertain interval theory is therefore introduced into the research of multiple fighters suppressing the integrated air defense system (IADS) problem. Considering that the combat information conditions are uncertain intervals, the payoff function of the game for multiple fighters suppressing the IADS is modeled. Using the operation rules for interval numbers and the possibility degree, an improved chaotic particle swarm optimization (CPSO) is designed to solve the proposed model so as to obtain the optimal game solution. Comparison simulations are performed to analyze the influence of the weapons consumption and the distances of non-escaped zone and jamming on air combat result. Simulation results suggest that Nash equilibrium is achieved and verify the effectiveness of the proposed method. 展开更多
关键词 INTERVAL information integrated AIR defense system (IADS) AIR COMBAT CHAOTIC particle SWARM optimization (CPSO) game.
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Impact of the Assimilation Frequency of Radar Data with the ARPS 3DVar and Cloud Analysis System on Forecasts of a Squall Line in Southern China 预览
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作者 Yujie PAN Mingjun WANG 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第2期160-172,共13页
Assimilation configurations have significant impacts on analysis results and subsequent forecasts.A squall line system that occurred on 23 April 2007 over southern China was used to investigate the impacts of the data... Assimilation configurations have significant impacts on analysis results and subsequent forecasts.A squall line system that occurred on 23 April 2007 over southern China was used to investigate the impacts of the data assimilation frequency of radar data on analyses and forecasts.A three-dimensional variational system was used to assimilate radial velocity data,and a cloud analysis system was used for reflectivity assimilation with a 2-h assimilation window covering the initial stage of the squall line.Two operators of radar reflectivity for cloud analyses corresponding to single-and double-moment schemes were used.In this study,we examined the sensitivity of assimilation frequency using 10-,20-,30-,and 60-min assimilation intervals.The results showed that analysis fields were not consistent with model dynamics and microphysics in general;thus,model states,including dynamic and microphysical variables,required approximately 20 min to reach a new balance after data assimilation in all experiments.Moreover,a 20-min data assimilation interval generally produced better forecasts for both single-and double-moment schemes in terms of equitable threat and bias scores.We conclude that a higher data assimilation frequency can produce a more intense cold pool and rear inflow jets but does not necessarily lead to a better forecast. 展开更多
关键词 cloud analysis RADAR DATA ASSIMILATION DATA ASSIMILATION INTERVAL
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短裤特征截面廓形分析及间隙量预测模型构建 预览
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作者 李涛 杜磊 +2 位作者 孙洁 张益洁 邹奉元 《纺织学报》 EI CAS CSCD 北大核心 2019年第5期113-118,共6页
为探究短裤松量变化对截面廓形的影响,选取与裤装造型密切相关的腰围、臀围等特征截面进行研究。通过[TC]2三维扫描仪获取截面点云数据,利用小脑神经网络进行曲线拟合,提取最小外接矩形面积、厚宽比及间隙量表征截面廓形变化,通过回归... 为探究短裤松量变化对截面廓形的影响,选取与裤装造型密切相关的腰围、臀围等特征截面进行研究。通过[TC]2三维扫描仪获取截面点云数据,利用小脑神经网络进行曲线拟合,提取最小外接矩形面积、厚宽比及间隙量表征截面廓形变化,通过回归分析构建短裤间隙量与松量的预测模型。结果表明:短裤松量与臀围、裆围及裤口围截面厚宽比呈负相关,臀围、裆围处间隙量主要向截面两侧及后中部位累积,截面形状趋于宽扁;经两配对样本T检验,间隙量的预测值与实际测量结果之间无显著差异,间隙量预测模型的拟合优度较好。研究结果可为建立人体、服装截面廓形及三维仿真之间的关系提供参考。 展开更多
关键词 短裤 松量 廓形 小脑神经网络 间隙量
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区域快线区间用地范围的划定标准与原则 预览
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作者 王悦欣 《城市轨道交通研究》 北大核心 2019年第3期16-18,105共4页
区域快线作为大型基建类工程,与城市的用地矛盾日益突出,因此亟需梳理区域快线沿线用地需求,明确用地范围,为城市用地规划与控制提供决策支持。根据铁路和城市轨道交通沿线用地的相关法律法规,以及区域快线自身的特点,对区域快线沿线用... 区域快线作为大型基建类工程,与城市的用地矛盾日益突出,因此亟需梳理区域快线沿线用地需求,明确用地范围,为城市用地规划与控制提供决策支持。根据铁路和城市轨道交通沿线用地的相关法律法规,以及区域快线自身的特点,对区域快线沿线用地进行分类,明确用地需求和划定用地范围,为城市用地规划与控制提供参考。 展开更多
关键词 区域快线 区间 用地范围 划定标准 划定原则
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