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911.
The reliability index approach (RIA) is one of the effective tools for solving the reliability-based design optimization (RBDO) probabilistic model, which models the uncertainties with probability constraints. However, its wide application in engineering is limited due to low efficiency and convergence problems. The RIA-based modified reliability index approach (MRIA) appears to be very robust and accurate than RIA but yields inefficient for the most probable point (MPP) search with highly nonlinear probabilistic constraints. In this study, an enhanced modified reliability index approach (EMRIA) is developed to improve the efficiency and robustness of searching for MPP and is utilized for RBDO. In the EMRIA, an innovative active set using rigorous inequality is applied to construct the region of exploring for MPP, where the unnecessary probabilistic constraint could be eliminated adaptively during the iterative process. Moreover, the double loop strategy (DLS) is integrated into the EMRIA to strengthen the efficiency and robustness of large-scale RBDO problems. Two numerical examples demonstrated that the EMRIA is an efficient and robust method for MPP search in comparison with current first-order reliability methods. Six RBDO problems quoted also indicate that DLS-based EMRIA has good performance to solve complex RBDO problems. 相似文献
912.
针对铅锌烧结过程中影响烧结综合透气性的因素具有不确定性以及目前已知的预测模型存在建模过程复杂的特点,利用改进的灰色理论来建立其预测模型.首先,考虑到灰色理论能在一定程度上降低不确定性带来的影响以及建模过程简单,建立了基于灰色理论的综合透气性预测模型.接着,针对建模数据序列的单调性改变后传统灰色理论不能及时跟踪数据序列变化的情况,根据建模数据序列单调性改变后的数据个数以及结合具体的单调性改变情况,提出了相应的修正公式,对传统灰色理论的预测结果进行适当的修正.实验结果表明,所提出的改进灰色理论比传统的灰色理论能在一定程度上提高预测精度. 相似文献
913.
W. Raskob;N.A. Beresford;T. Duranova;I. Korsakissok;A. Mathieu;M. Montero;T. Müller;C. Turcanu;C. Woda 《Radioprotection》2020,55(1):S7-S15
The project CONFIDENCE (COping with uNcertainties For Improved modelling and DEcision making in Nuclear emergenCiEs) performed research on identifying and reducing uncertainties in the release and post-release phases of an emergency. The project started in January 2017 as part of the European Joint Programme CONCERT. It brought together 31 partners from 18 countries and involved members of five European Radiation Protection Platforms namely ALLIANCE,EURADOS,MELODI,NERIS and SHARE. The work program included research on early phase modelling and monitoring considering weather,source term and monitoring uncertainties. Consideration of social,ethical and communication aspects was a key part of our activities. This comprised strategy development in the transition phase together with stakeholder interaction,understanding of the population and which uncertainties are relevant for decision-making. Finally,formal decision aiding techniques were investigated and tested.https://doi.org/10.1051/radiopro/2020008 相似文献
914.
I. Korsakissok;R. Périllat;S. Andronopoulos;P. Bedwell;E. Berge;T. Charnock;G. Geertsema;F. Gering;T. Hamburger;H. Klein;S. Leadbetter;O.C. Lind;T. Pázmándi;Cs. Rudas;B. Salbu;A. Sogachev;N. Syed;J.M. Tomas;M. Ulimoen;H. De Vries;J. Wellings 《Radioprotection》2020,55(1):S57-S68
In the framework of the European project CONFIDENCE,Work Package 1 (WP1) focused on the uncertainties in the pre- and early phase of a radiological emergency,when environmental observations are not available and the assessment of the environmental and health impact of the accident largely relies on atmospheric dispersion modelling. The latter is subject to large uncertainties coming from,in particular,meteorological and release data. In WP1,several case studies were identified,including hypothetical accident scenarios in Europe and the Fukushima accident,for which participants propagated input uncertainties through their atmospheric dispersion and subsequent dose models. This resulted in several ensembles of results (consisting of tens to hundreds of simulations) that were compared to each other and to radiological observations (in the Fukushima case). These ensembles were analysed in order to answer questions such as: among meteorology,source term and model-related uncertainties,which are the predominant ones? Are uncertainty assessments very different between the participants and can this inter-ensemble variability be explained? What are the optimal ways of characterizing and presenting the uncertainties? Is the ensemble modelling sufficient to encompass the observations,or are there sources of uncertainty not (sufficiently) taken into account? This paper describes the case studies of WP1 and presents some illustrations of the results,with a summary of the main findings.https://doi.org/10.1051/radiopro/2020013 相似文献
915.
目前,在概率潮流计算方法中,不确定性因素多数仅考虑了负荷的不确定性及发电机的随机故障,而不计及网络结构的变化。文中提出一种概率潮流计算新方法,综合考虑了负荷、发电机、网络结构不确定性对潮流结果的影响。文中推导了线路故障时节点注入功率与各支路有功功率的线性关系,应用半不变量法和Gram-Charlier级数展开式求取各支路潮流的概率分布,避免了复杂的卷积运算;结合补偿法及全概率理论来处理网络结构变化的随机因素,建立了综合考虑负荷随机变化、发电机随机故障和网络结构随机变化的概率潮流计算模型,可以快速求得各支路潮流的概率分布函数（CDF）和概率密度函数（PDF）。通过对IEEE 39节点及某区域电网实际系统的算例分析,表明网络结构的不确定性对待求量的概率分布有显著影响。因此,利用所提方法得到的概率潮流结果能为规划人员提供更准确和全面的信息。通过与蒙特卡罗方法进行比较,验证了该方法的快速性与准确性,说明所提方法具有实际应用前景。 相似文献
916.
Metehan Yayla Ehsan Arabi Ali Turker Kutay Tansel Yucelen 《International Journal of Adaptive Control and Signal Processing》2018,32(8):1124-1144
In this paper, we propose a command governor‐based adaptive control architecture for stabilizing uncertain dynamical systems with not only matched but also unmatched uncertainties and achieving the desired command following performance of a user‐defined subset of the accessible states. In our proposed solution, online least‐squares solutions for the matched and unmatched parameters are obtained through integration method and they are employed in the adaptive control framework. Specifically, the matched uncertainty is identified and its effect upon the system behavior is entirely attenuated. Moreover, using the unmatched uncertainty approximation obtained through radial basis function neural networks, the command governor signal is designed to achieve the desired command following performance of the user‐defined subset of the accessible states. With this command governor‐based model reference adaptive control architecture, the tracking error of the selected states can be made arbitrarily small by judiciously tuning the design parameters. In addition to the analysis of the closed‐loop system stability using methods from the Lyapunov theory, our findings are also illustrated through numerical examples. 相似文献
917.
B. S. Lazarov M. Schevenels O. Sigmund 《International journal for numerical methods in engineering》2012,90(11):1321-1336
The aim of this paper was to present a topology optimization methodology for obtaining robust designs insensitive to small uncertainties in the geometry. The variations are modeled using a stochastic field. The model can represent spatially varying geometry imperfections in devices produced by etching techniques. Because of under‐etching or over‐etching parts of the structure may become thinner or thicker than a reference design supplied to the manufacturer. The uncertainties are assumed to be small and their influence on the system response is evaluated using perturbation techniques. Under the above assumptions, the proposed algorithm provides a computationally cheap alternative to previously introduced stochastic optimization methods based on Monte Carlo sampling. The method is demonstrated on the design of a minimum compliance cantilever beam and a compliant mechanism. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
918.
Seldom has research regarding manufacturing process modelling considered the two common types of uncertainties which are caused by randomness as in material properties and by fuzziness as in the inexact knowledge in manufacturing processes. Accuracies of process models can be downgraded if these uncertainties are ignored in the development of process models. In this paper, a hybrid swarm intelligence algorithm for developing process models which intends to achieve significant accuracies for manufacturing process modelling by addressing these two uncertainties is proposed. The hybrid swarm intelligence algorithm first applies the mechanism of particle swarm optimisation to generate structures of process models in polynomial forms, and then it applies the mechanism of fuzzy least square regression algorithm to determine fuzzy coefficients on polynomials so as to address the two uncertainties, fuzziness and randomness. Apart from addressing the two uncertainties, the common feature in manufacturing processes, nonlinearities between process parameters, which are not inevitable in manufacturing processes, can also be addressed. The effectiveness of the hybrid swarm algorithm is demonstrated by modelling of the solder paste dispensing process. 相似文献
919.
In this paper, we describe a practical nonintrusive multiscale solver that permits consideration of uncertainties in heterogeneous materials without exhausting the available computational resources. The computational complexity of analyzing heterogeneous material systems is governed by the physical and probability spaces at multiple scales. To deal with these large spaces, we employ reduced order homogenization approach in combination with the Karhunen–Loeve expansion and stochastic collocation method based on sparse grid. The resulting nonintrusive multiscale solver, which is aimed at providing practical solutions for complex multiscale stochastic problems, has been verified against the Latin Hypercube Monte–Carlo method. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
920.
具有输入与状态时滞的非线性系统的模糊保性能控制 总被引：2，自引：0，他引：2
针对一类具有输入与状态时滞的参数不确定非线性系统,基于T-S模糊模型,讨论该系统的保性能控制问题。通过构造状态反馈控制器,提出了在给定的性能指标和控制律下,闭环系统是二次保性能稳定的充分条件,并以线性矩阵不等式(LMI)的形式表示,数值算例显示该设计方法是有效的。 相似文献