排序方式: 共有62条查询结果,搜索用时 15 毫秒
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体系(SoS)在遭受内部或外部的干扰时性能会受到影响,体系结构作为体系设计和构建的基础,其弹性不仅是反映体系性能恢复能力的一个重要指标,更是体系演化性的重要体现。提出了一种基于弹性的体系结构评价方法,对体系的组件或系统进行重要度分析(CIMs)。首先,给出了体系结构弹性的明确定义并构建了相关的数学模型,综合权衡了性能损耗与恢复时间对体系组件重要度的影响;其次,通过分析不同的干扰事件和恢复策略,构建了基于重要度分析的体系弹性优化模型,并重点分析了其对体系性能恢复的影响;最后,以某体系结构的弹性评价为例,对本文提出的模型和方法进行了验证,优化后的恢复策略使体系性能的恢复效率有显著的提高。 相似文献
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基于模糊聚类的近距空战决策过程重构与评估 总被引:2,自引:0,他引:2
目前大量研究集中在空战的智能决策和解决近距空战评估结果"是什么"的问题上,却极少关注评估结果的"为什么"。根据空战训练中记录的客观数据的变化特征,提出基于模糊聚类的方法来计算决策序列,构建模糊粗糙决策系统,以实现对近距空战决策过程的重构;通过计算分析条件属性之间的相对重要度,对具有相似重要度的决策对象序列进行二次聚类划分,分析出关键决策点集合。通过实例研究,从空战能量和相对方位2个方面对近距空战决策过程进行了评估分析。结果表明,从空战决策的角度可认为关键决策点集合是产生评估结果的原因。 相似文献
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基于优化Kriging模型和重要抽样法的结构可靠度混合算法 总被引:2,自引:0,他引:2
结构可靠度分析计算通常采用多项式响应面拟合隐式极限状态函数,但对于复杂航空航天机械结构产品极限状态方程往往表现出高度非线性,此时多项式响应面的模拟精度不够就会造成计算不收敛。为了提高结构可靠度计算的精度、效率和收敛性,提出了基于优化Kriging模型和重要抽样法的结构可靠度计算方法。首先,利用人工蜂群算法对Kriging模型的参数进行优化;再用优化后的模型模拟隐式极限状态函数,结合重要抽样法不断修正抽样重心,逐步提高模拟精度以达到给定要求;最后,结合一阶矩法(FORM)/二阶矩法(SORM)经典算法求解结构可靠度。该方法提高了高度非线性隐式极限状态方程可靠度计算的精度和收敛性,并且具有较高的计算效率。 相似文献
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《中国航空学报》2020,33(4):1218-1227
The application of reliability analysis and reliability sensitivity analysis methods to complicated structures faces two main challenges: small failure probability (typical less than 10−5) and time-demanding mechanical models. This paper proposes an improved active learning surrogate model method, which combines the advantages of the classical Active Kriging – Monte Carlo Simulation (AK-MCS) procedure and the Adaptive Linked Importance Sampling (ALIS) procedure. The proposed procedure can, on the one hand, adaptively produce a series of intermediate sampling density approaching the quasi-optimal Importance Sampling (IS) density, on the other hand, adaptively generate a set of intermediate surrogate models approaching the true failure surface of the rare failure event. Then, the small failure probability and the corresponding reliability sensitivity indices are efficiently estimated by their IS estimators based on the quasi-optimal IS density and the surrogate models. Compared with the classical AK-MCS and Active Kriging – Importance Sampling (AK-IS) procedure, the proposed method neither need to build very large sample pool even when the failure probability is extremely small, nor need to estimate the Most Probable Points (MPPs), thus it is computationally more efficient and more applicable especially for problems with multiple MPPs. The effectiveness and engineering applicability of the proposed method are demonstrated by one numerical test example and two engineering applications. 相似文献
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Traditional Global Sensitivity Analysis (GSA) focuses on ranking inputs according to their contributions to the output uncertainty.However,information about how the specific regions inside an input affect the output is beyond the traditional GSA techniques.To fully address this issue,in this work,two regional moment-independent importance measures,Regional Importance Measure based on Probability Density Function (RIMPDF) and Regional Importance Measure based on Cumula tive Distribution Function (RIMCDF),are introduced to find out the contributions of specific regions of an input to the whole output distribution.The two regional importance measures prove to be reasonable supplements of the traditional GSA techniques.The ideas of RIMPDF and RIMCDF are applied in two engineering examples to demonstrate that the regional moment-independent importance analysis can add more information concerning the contributions of model inputs. 相似文献
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针对CCAR33.70条款对涡轮盘开展概率风险评估的要求,研究了响应面法在定义重点采样区间以及计算裂纹扩展寿命中的应用,给出了在蒙特卡洛模拟过程中应用响应面法定义失效域,缩短样本方差、提高抽样效率的方法.分析结果表明应用重点采样法可以极大地提高抽样效率.采用重点采样法获得的失效样本数与总样本数的比例高达94%,远大于传统的直接抽样法获得的失效样本数与总样本数的比例(仅为33%).该方法可以在保证分析精度的条件下减少样本的数量.另外,应用响应面法拟合寿命近似方程,可以极大地缩减裂纹扩展寿命的计算时间:利用寿命近似方程开展104次随机抽样所花费的时间仅有2min,远低于应用传统寿命计算方法所花费的时间(288 min).通过对寿命近似方程的寿命计算误差分析可以看出:最大计算误差仅有1.0%,计算结果与传统裂纹扩展寿命模型的计算结果吻合度高.该研究成果可以提高涡轮盘概率风险评估的效率. 相似文献
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