In engineering applications, probabilistic reliability theory appears to be presently the most important method, however, in many cases precise probabilistic reliability theory cannot be considered as adequate and cre...In engineering applications, probabilistic reliability theory appears to be presently the most important method, however, in many cases precise probabilistic reliability theory cannot be considered as adequate and credible model of the real state of actual affairs. In this paper, we developed a hybrid of probabilistic and non-probabilistic reliability theory, which describes the structural uncertain parameters as interval variables when statistical data are found insufficient. By using the interval analysis, a new method for calculating the interval of the structural reliability as well as the reliability index is introduced in this paper, and the traditional probabilistic theory is incorporated with the interval analysis. Moreover, the new method preserves the useful part of the traditional probabilistic reliability theory, but removes the restriction of its strict requirement on data acquisition. Example is presented to demonstrate the feasibility and validity of the proposed theory.展开更多
The aim of this paper is to propose a theoretical approach for performing the nonprobabilistic reliability analysis of structure.Due to a great deal of uncertainties and limited measured data in engineering practice,t...The aim of this paper is to propose a theoretical approach for performing the nonprobabilistic reliability analysis of structure.Due to a great deal of uncertainties and limited measured data in engineering practice,the structural uncertain parameters were described as interval variables.The theoretical analysis model was developed by starting from the 2-D plane and 3-D space.In order to avoid the loss of probable failure points,the 2-D plane and 3-D space were respectively divided into two parts and three parts for further analysis.The study pointed out that the probable failure points only existed among extreme points and root points of the limit state function.Furthermore,the low-dimensional analytical scheme was extended to the high-dimensional case.Using the proposed approach,it is easy to find the most probable failure point and to acquire the reliability index through simple comparison directly.A number of equations used for calculating the extreme points and root points were also evaluated.This result was useful to avoid the loss of probable failure points and meaningful for optimizing searches in the research field.Finally,two kinds of examples were presented and compared with the existing computation.The good agreements show that the proposed theoretical analysis approach in the paper is correct.The efforts were conducted to improve the optimization method,to indicate the search direction and path,and to avoid only searching the local optimal solution which would result in missed probable failure points.展开更多
Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of off...Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.展开更多
目的探讨中文版心理弹性量表(connor-davidson resilience scale,CD-RISC)在非霍奇金淋巴瘤(non-Hodgkin lymphoma,NHL)中的信效度。方法选取福建医科大学附属第二医院2020年1月-2022年12月238例NHL患者作为研究对象。采用中文版CD-RIS...目的探讨中文版心理弹性量表(connor-davidson resilience scale,CD-RISC)在非霍奇金淋巴瘤(non-Hodgkin lymphoma,NHL)中的信效度。方法选取福建医科大学附属第二医院2020年1月-2022年12月238例NHL患者作为研究对象。采用中文版CD-RISC对其进行问卷调查,并分析不同亚组人群评分差异。采用验证性因子分析(confirmatory factor analysis,CFA)评价CD-RISC的信效度。结果CDRISC内在一致性信度指标:总量表Cronbach'sα系数为0.812,坚韧(tenacity,TEN)维度为0.904,自强(strength,STR)维度为0.906,(optimism,OPT)维度为0.755。CD-RISC折半信度Spearman-Brown系数为0.843。验证性因子结果显示,χ^(2)=901.094,自由度(degree of freedom,df)=272,χ^(2)/df=3.313,比较拟合指数(comparative fit index,CFI)、调整拟合优度指数(adjusted goodness of fit index,AGFI)、拟合优度指数(goodness of fit index,GFI)值分别为0.800、0.733、0.777,近似误差均方根(root mean square error of approximation,RMSEA)为0.099。结论中文版CD-RISC在NHL患者中具有很好的信效度,能为测量NHL患者的心理弹性水平提供一种新的工具。展开更多
基金the National Outstanding Youth Science Foundation of China (10425208)Civil 863 Program (2006AA04Z410)111 Project (B07009)
文摘In engineering applications, probabilistic reliability theory appears to be presently the most important method, however, in many cases precise probabilistic reliability theory cannot be considered as adequate and credible model of the real state of actual affairs. In this paper, we developed a hybrid of probabilistic and non-probabilistic reliability theory, which describes the structural uncertain parameters as interval variables when statistical data are found insufficient. By using the interval analysis, a new method for calculating the interval of the structural reliability as well as the reliability index is introduced in this paper, and the traditional probabilistic theory is incorporated with the interval analysis. Moreover, the new method preserves the useful part of the traditional probabilistic reliability theory, but removes the restriction of its strict requirement on data acquisition. Example is presented to demonstrate the feasibility and validity of the proposed theory.
基金the National Natural Science Foundation of China (51408444, 51708428)
文摘The aim of this paper is to propose a theoretical approach for performing the nonprobabilistic reliability analysis of structure.Due to a great deal of uncertainties and limited measured data in engineering practice,the structural uncertain parameters were described as interval variables.The theoretical analysis model was developed by starting from the 2-D plane and 3-D space.In order to avoid the loss of probable failure points,the 2-D plane and 3-D space were respectively divided into two parts and three parts for further analysis.The study pointed out that the probable failure points only existed among extreme points and root points of the limit state function.Furthermore,the low-dimensional analytical scheme was extended to the high-dimensional case.Using the proposed approach,it is easy to find the most probable failure point and to acquire the reliability index through simple comparison directly.A number of equations used for calculating the extreme points and root points were also evaluated.This result was useful to avoid the loss of probable failure points and meaningful for optimizing searches in the research field.Finally,two kinds of examples were presented and compared with the existing computation.The good agreements show that the proposed theoretical analysis approach in the paper is correct.The efforts were conducted to improve the optimization method,to indicate the search direction and path,and to avoid only searching the local optimal solution which would result in missed probable failure points.
文摘Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.
文摘目的探讨中文版心理弹性量表(connor-davidson resilience scale,CD-RISC)在非霍奇金淋巴瘤(non-Hodgkin lymphoma,NHL)中的信效度。方法选取福建医科大学附属第二医院2020年1月-2022年12月238例NHL患者作为研究对象。采用中文版CD-RISC对其进行问卷调查,并分析不同亚组人群评分差异。采用验证性因子分析(confirmatory factor analysis,CFA)评价CD-RISC的信效度。结果CDRISC内在一致性信度指标:总量表Cronbach'sα系数为0.812,坚韧(tenacity,TEN)维度为0.904,自强(strength,STR)维度为0.906,(optimism,OPT)维度为0.755。CD-RISC折半信度Spearman-Brown系数为0.843。验证性因子结果显示,χ^(2)=901.094,自由度(degree of freedom,df)=272,χ^(2)/df=3.313,比较拟合指数(comparative fit index,CFI)、调整拟合优度指数(adjusted goodness of fit index,AGFI)、拟合优度指数(goodness of fit index,GFI)值分别为0.800、0.733、0.777,近似误差均方根(root mean square error of approximation,RMSEA)为0.099。结论中文版CD-RISC在NHL患者中具有很好的信效度,能为测量NHL患者的心理弹性水平提供一种新的工具。
