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直接误差估计的一个新方法 被引量:1
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作者 田天海 王能超 《应用数学》 CSCD 北大核心 1989年第3期39-48,共10页
本文利用文[1]的方法进行误差估计产生了严重过估的事实,从而提出了一个估计误差的新方法。通过严格的分析树高定义,给出了绝对误差和相对误差二种形式的误差估计方法,并针对并行算法的特点,给出了向量运算算法的误差估计方法。利用该... 本文利用文[1]的方法进行误差估计产生了严重过估的事实,从而提出了一个估计误差的新方法。通过严格的分析树高定义,给出了绝对误差和相对误差二种形式的误差估计方法,并针对并行算法的特点,给出了向量运算算法的误差估计方法。利用该方法本文给出了几个典型问题的算法的误差估计,结果表明,它和已有的结论是一致的。 展开更多
关键词 直接误差估计 并行算法 向量运算
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三维接触边界元法的一种误差直接估计 被引量:2
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作者 刘永健 姚振汉 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 2003年第11期1499-1502,1506,共5页
将作者所在研究组提出的二维弹性力学问题边界元解误差的直接估计推广到三维问题,给出了确定与域内解连续的边界位移的一种精确有效的方法。在此基础上提出将接触体接触单元间与域内解连续的边界位移之差的某种度量作为三维弹性接触问... 将作者所在研究组提出的二维弹性力学问题边界元解误差的直接估计推广到三维问题,给出了确定与域内解连续的边界位移的一种精确有效的方法。在此基础上提出将接触体接触单元间与域内解连续的边界位移之差的某种度量作为三维弹性接触问题边界元法的一种误差直接估计,并且提出了三维弹性接触问题的一种自适应边界元法计算方案。这种方案为确定没有解析解可作比较的复杂接触问题的边界元解精度提供了可能。文中对于三维弹性接触问题,给出了一个计算误差直接估计及自适应边界元法的算例。 展开更多
关键词 三维接触边界元法 误差直接估计 弹性接触 边界位移 有限元
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Influence of age in estimating maximal oxygen uptake 被引量:2
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作者 Christina G de Souza Silva Barry A Franklin +1 位作者 Daniel E Forman Claudio Gil S Araujo 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2016年第2期126-131,共6页
Objective To assess the influence of age on the error of estimate (EE) of maximal oxygen uptake (VO2max) using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO2 max is ... Objective To assess the influence of age on the error of estimate (EE) of maximal oxygen uptake (VO2max) using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO2 max is associated with a substantial EE, often exceeding 20%, possibly due to intrinsic variability of mechanical efficiency. Methods 1850 adults (68% men), aged 18 to 91 years, underwent maximal cycle ergometer cardiopulmonary exercise testing. Cardiorespiratory fitness (CRF) was assessed relative to sex and age [younger (18 to 35 years), middle-aged (36 to 60 years) and older (〉 60 years)]. VO2max [mL.(kg.min)-1] was directly measured by assessment of gas exchange and estimated using sex and population specific-equations. Measured and estimated values of VO2max and related EE were compared among the three age- and sex-specific groups. Results Directly measured VO2max of men and women were 29.5 ± 10.5 mL.(kg.min)-1 and 24.2 ± 9.0 mL.(kg·min) -1 (P 〈 0.01). EE [mL·(kg·min)-1] and percent errors (%E) for men and women had similar values, 0.5 ± 3.2 and 0.4 ± 2.9 mL·(kg·min)-1, and -0.8 ± 13.1% and -1.7 ± 15.4% (P 〉 0.05), respectively. EE and %E for each age-group were, respectively, for men: younger = 1.9 ± 4.1 mL·(kg·min)-1 and 3.8 ± 10.5%, middle-aged = 0.6 ± 3.1 mL.(kg·min)-1 and 0.4 ± 10.3%, older = -0.2 ± 2.7 mL·(kg·min) -1 and -4.2 ± 16.6% (P 〈 0.01); and for women: younger = 1.2 ± 3.1 mL.(kg.min)-1 and 2.7 ±10.0%, middle-aged = 0.7 ± 2.8 mL·(kg·min)-1 and 0.5 ± 11.1%, older = -0.8 ± 2.3 mL-(kg·min)-1 and -9.5 ± 22.4% (P 〈 0.01). Conclusion VO2max were underestimated in younger age-groups and were overestimated in older age groups. Age significantly influences the magnitude of the EE of VO2max in both men and women and should be considered when CRF is estimated using population specific equations, rather than directly measured. 展开更多
关键词 AGING Cardiopulmonary exercise testing Error of measurement
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