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Abstract

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Grey Systems: Theory and Application, vol. 8 no. 4
Type: Research Article
ISSN: 2043-9377

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Article
Publication date: 16 October 2020

Xiaoyu Yang, Zhigeng Fang, Xiaochuan Li, Yingjie Yang and David Mba

Online health monitoring of large complex equipment has become a trend in the field of equipment diagnostics and prognostics due to the rapid development of sensing and…

Abstract

Purpose

Online health monitoring of large complex equipment has become a trend in the field of equipment diagnostics and prognostics due to the rapid development of sensing and computing technologies. The purpose of this paper is to construct a more accurate and stable grey model based on similar information fusion to predict the real-time remaining useful life (RUL) of aircraft engines.

Design/methodology/approach

First, a referential database is created by applying multiple linear regressions on historical samples. Then similarity matching is conducted between the monitored engine and historical samples. After that, an information fusion grey model is applied to predict the future degradation trajectory of the monitored engine considering the latest trend of monitored sensory data and long-term trends of several similar referential samples, and the real-time RUL is obtained correspondingly.

Findings

The results of comparative analysis reveal that the proposed model, which is called similarity-based information fusion grey model (SIFGM), could provide better RUL prediction from the early degradation stage. Furthermore, SIFGM is still able to predict system failures relatively accurately when only partial information of the referential samples is available, making the method a viable choice when the historical whole life cycle data are scarce.

Research limitations/implications

The prediction of SIFGM method is based on a single monotonically changing health indicator (HI) synthesized from monitoring sensory signals, which is assumed to be highly relevant to the degradation processes of the engine.

Practical implications

The SIFGM can be used to predict the degradation trajectories and RULs of those online condition monitoring systems with similar irreversible degradation behaviors before failure occurs, such as aircraft engines and centrifugal pumps.

Originality/value

This paper introduces the similarity information into traditional GM(1,1) model to make it more suitable for long-term RUL prediction and also provide a solution of similarity-based RUL prediction with limited historical whole life cycle data.

Details

Grey Systems: Theory and Application, vol. 11 no. 3
Type: Research Article
ISSN: 2043-9377

Keywords

Content available
Article
Publication date: 17 December 2019

Yingjie Yang, Sifeng Liu and Naiming Xie

The purpose of this paper is to propose a framework for data analytics where everything is grey in nature and the associated uncertainty is considered as an essential part…

Abstract

Purpose

The purpose of this paper is to propose a framework for data analytics where everything is grey in nature and the associated uncertainty is considered as an essential part in data collection, profiling, imputation, analysis and decision making.

Design/methodology/approach

A comparative study is conducted between the available uncertainty models and the feasibility of grey systems is highlighted. Furthermore, a general framework for the integration of grey systems and grey sets into data analytics is proposed.

Findings

Grey systems and grey sets are useful not only for small data, but also big data as well. It is complementary to other models and can play a significant role in data analytics.

Research limitations/implications

The proposed framework brings a radical change in data analytics. It may bring a fundamental change in our way to deal with uncertainties.

Practical implications

The proposed model has the potential to avoid the mistake from a misleading data imputation.

Social implications

The proposed model takes the philosophy of grey systems in recognising the limitation of our knowledge which has significant implications in our way to deal with our social life and relations.

Originality/value

This is the first time that the whole data analytics is considered from the point of view of grey systems.

Details

Marine Economics and Management, vol. 2 no. 2
Type: Research Article
ISSN: 2516-158X

Keywords

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Article
Publication date: 7 November 2016

Sifeng Liu, Handan Rui, Zhigeng Fang, Yingjie Yang and Jeffrey Forrest

The purpose of this paper is to present the terms of grey numbers and its operations.

Abstract

Purpose

The purpose of this paper is to present the terms of grey numbers and its operations.

Design/methodology/approach

The definitions of elementary terms about grey numbers and its operations are presented one by one.

Findings

The reader could know the basic explanation about the important terms about grey numbers and its operations from this paper.

Practical implications

Many of the colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.

Originality/value

It is a fundamental work to standardise all the definitions of terms for a new discipline. It is also propitious to spread the universal principles of grey system theory.

Details

Grey Systems: Theory and Application, vol. 6 no. 3
Type: Research Article
ISSN: 2043-9377

Keywords

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Article
Publication date: 6 February 2017

Sifeng Liu, Hongyang Zhang and Yingjie Yang

The purpose of this paper is to present the terms of grey incidence analysis models.

Abstract

Purpose

The purpose of this paper is to present the terms of grey incidence analysis models.

Design/methodology/approach

The definitions of basic terms about various grey incidence analysis models are presented one by one.

Findings

The reader could know the basic explanation about the important terms about various grey incidence analysis models from this paper.

Practical implications

Many of the authors’ colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.

Originality/value

It is a fundamental work to standardize all the definitions of terms for a new discipline. It is also propitious to spread and universal of grey system theory.

Details

Grey Systems: Theory and Application, vol. 7 no. 1
Type: Research Article
ISSN: 2043-9377

Keywords

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Article
Publication date: 6 February 2017

Sifeng Liu and Yingjie Yang

The purpose of this paper is to present the terms of grey forecasting models and techniques.

Abstract

Purpose

The purpose of this paper is to present the terms of grey forecasting models and techniques.

Design/methodology/approach

The definitions of basic terms about grey forecasting models and techniques are presented one by one.

Findings

The reader could know the basic explanation about the important terms about various grey forecasting models and techniques from this paper.

Practical implications

Many of the authors’ colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.

Originality/value

It is a fundamental work to standardise all the definitions of terms for a new discipline. It is also propitious to spread and universal of grey system theory.

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Article
Publication date: 7 November 2016

Sifeng Liu, Naiming Xie, Yingjie Yang and Jeffrey Forrest

The purpose of this paper is to present the terms of sequence operators and grey data mining.

Abstract

Purpose

The purpose of this paper is to present the terms of sequence operators and grey data mining.

Design/methodology/approach

The definitions of basic terms about sequence operators and grey data mining are presented one by one.

Findings

The reader could know the basic explanation about the important terms about sequence operators and grey data mining from this paper.

Practical implications

Many of the colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.

Originality/value

It is a fundamental work to standardize all the definitions of terms for a new discipline. It is also propitious to spread the universal principles of grey system theory.

Details

Grey Systems: Theory and Application, vol. 6 no. 3
Type: Research Article
ISSN: 2043-9377

Keywords

Content available
Article
Publication date: 28 January 2019

Sifeng Liu and Yingjie Yang

Abstract

Details

Grey Systems: Theory and Application, vol. 9 no. 1
Type: Research Article
ISSN: 2043-9377

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Article
Publication date: 24 April 2020

Sifeng Liu, Qi Li and Yingjie Yang

The purpose of this paper is to present a novel synthetic index of two counts and mathematical model for researcher evaluation.

Abstract

Purpose

The purpose of this paper is to present a novel synthetic index of two counts and mathematical model for researcher evaluation.

Design/methodology/approach

A synthetic index L for researcher evaluation considering both the total number of other citations (C) and nonacademic impact (I) and a synthetic evaluation model are proposed in this paper. C and I are verified impact indexes. According to investigation by Delphi method, researchers are divided into five different classes of “below average,” “average,” “good,” “excellent” and “stellar.” The threshold values for counts C of grey class “stellar” are determined by deep investigation. The possibility functions of the two counts C and I on four grey classes of “below average,” “average,” “good” and “excellent” are built.

Findings

The novel synthetic index of two counts and mathematical model for researcher evaluation provide a better way to conduct researcher assessment.

Practical implications

The synthetic index L presented in this paper can be used to evaluate a researcher. It's more reasonable than the current research assessment indexes such as the number of publications and the numbers of so-called high-quality journal publications and the amount of granted funds and so on. The synthetic index L reflects the actual value created by a researcher. No artificial maneuver can change them significantly.

Originality/value

A synthetic index L for researcher evaluation considering both the total number of other citations (C) and nonacademic impact (I) and a synthetic evaluation model are proposed in this paper.

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Article
Publication date: 26 May 2020

Changhai Lin, Zhengyu Song, Sifeng Liu, Yingjie Yang and Jeffrey Forrest

The purpose of this paper is to analyze the mechanism and filter efficacy of accumulation generation operator (AGO)/inverse accumulation generation operator (IAGO) in the…

Abstract

Purpose

The purpose of this paper is to analyze the mechanism and filter efficacy of accumulation generation operator (AGO)/inverse accumulation generation operator (IAGO) in the frequency domain.

Design/methodology/approach

The AGO/IAGO in time domain will be transferred to the frequency domain by the Fourier transform. Based on the consistency of the mathematical expressions of the AGO/IAGO in the gray system and the digital filter in digital signal processing, the equivalent filter model of the AGO/IAGO is established. The unique methods in digital signal processing systems “spectrum analysis” of AGO/IAGO are carried out in the frequency domain.

Findings

Through the theoretical study and practical example, benefit of spectrum analysis is explained, and the mechanism and filter efficacy of AGO/IAGO are quantitatively analyzed. The study indicated that the AGO is particularly suitable to act on the system's behavior time series in which the long period parts is the main factor. The acted sequence has good effect of noise immunity.

Practical implications

The AGO/IAGO has a wonderful effect on the processing of some statistical data, e.g. most of the statistical data related to economic growth, crop production, climate and atmospheric changes are mainly affected by long period factors (i.e. low-frequency data), and most of the disturbances are short-period factors (high-frequency data). After processing by the 1-AGO, its high frequency content is suppressed, and its low frequency content is amplified. In terms of information theory, this two-way effect improves the signal-to-noise ratio greatly and reduces the proportion of noise/interference in the new sequence. Based on 1-AGO acting, the information mining and extrapolation prediction will have a good effect.

Originality/value

The authors find that 1-AGO has a wonderful effect on the processing of data sequence. When the 1-AGO acts on a data sequence X, its low-pass filtering effect will benefit the information fluctuations removing and high-frequency noise/interference reduction, so the data shows a clear exponential change trends. However, it is not suitable for excessive use because its equivalent filter has poles at the non-periodic content. But, because of pol effect at zero frequency, the 1-AGO will greatly amplify the low-frequency information parts and suppress the high-frequency parts in the information at the same time.

Details

Grey Systems: Theory and Application, vol. 11 no. 1
Type: Research Article
ISSN: 2043-9377

Keywords

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