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A fault location strategy based on information fusion and CODAS algorithm under epistemic uncertainty

Duan Rongxing, Chen Li, He Jiejun, Huang Shujuan

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 3

478--488

EN

Application of new technology in modern systems not only substantially improves the performance, but also presents a severe challenge to fault location of these systems. This paper presents a new fault location strategy for maintenance personnel to recover them based on information fusion and improved CODAS algorithm. Firstly, a fault tree is adopted to develop the failure model of a complex system, and failure probability of components is determined by expert evaluations to handle the uncertainty problem. Moreover, a fault tree is converted into an evidence network to obtain importance degrees, which are used to construct a diagnostic decision table together with the risk priority number. Additionally, these results are updated to optimize the maintenance process using sensor information. A novel dynamic location strategy is designed based on interval CODAS algorithm and optimal fault location strategy can be obtained. Finally, a real system is analyzed to demonstrate the feasibility of the proposed maintenance strategy.

2

Effective sensor placement based on a VIKOR method considering common cause failure in the presence of epistemic uncertainty

Duan Rong-Xing, He Jie-Jun, Feng Tao, Huang Shu-Juan, Chen Li

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 2

253--262

EN

Owing to expensive cost and restricted structure, limited sensors are allowed to install in modern systems to monitor the working state, which can improve their availability. Therefore, an effective sensor placement method is presented based on a VIKOR algorithm considering common cause failure (CCF) under epistemic uncertainty in this paper. Specifically, a dynamic fault tree (DFT) is developed to build a fault model to simulate dynamic fault behaviors and some reliability indices are calculated using a dynamic evidence network (DEN). Furthermore, a VIKOR method is proposed to choose the possible sensor locations based on these indices. Besides, a sensor model is introduced by using a priority AND gate (PAND) to describe the failure sequence between a sensor and a component. All placement schemes can be enumerated when the number of sensors is given, and the largest system reliability is the best alternative among the placement schemes. Finally, a case study shows that CCF has some influence on sensor placement and cannot be neglected in the reliabilitybased sensor placement.

3

Generation of three-port splitter by double-layer grating in second-order Littrow configuration

Gao Chenhao, Wang Bo, Fu Chen, Fang Jimin, Wen Kunhua, Meng Ziming, Nie Zhaogang, Xing Xiangjun, Chen Li, Lei Liang, Zhou Jinyun

Optica Applicata

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2020

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Vol. 50, nr 2

271--280

EN

In this paper, a novel double-layer three-port grating is described. The incident grating structure is in the second-order Littrow configuration. The grating region is composed of fused silica and Ta2O5.The designed grating beam splitter has high efficiency under TE polarization and TM polarization, respectively. The efficiency of two polarizations is more than 90%. In addition, compared with a single-layer three-port grating, this new beam splitter has good fabrication tolerance and incident bandwidth. Therefore, the optimized structure has a good application value.

4

Diffraction mechanism of five-port transmission gratings

Gao Chenhao, Wang Bo, Wen Kunhua, Meng Ziming, Wang Qu, Nie Zhaogang, Xing Xiangjun, Chen Li, Lei Liang, Zhou Jinyun

Optica Applicata

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2020

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Vol. 50, nr 4

609--618

EN

This paper designs a five-port transmission grating under normal incidence. Rigorous coupled-wave approach is used to optimize the grating parameters. The energy of the grating is mainly dispersed to the 0th, ±1st and ±2nd orders. The efficiency of each diffraction order under both polarizations is close to 20%. The modal method is used to describe the propagation mechanism of the two polarized lights in the grating, and the diffraction behavior of the grating is analyzed. In addition, the grating has a wide range of incident characteristics and a large process tolerance. Therefore, this five-port beam splitter with a connecting layer will be a good polarization-independent beam splitting device.