scholarly journals A Displacement Field Perception Method for Component Digital Twin in Aircraft Assembly

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5161
Author(s):  
Bing Liang ◽  
Wei Liu ◽  
Kun Liu ◽  
Mengde Zhou ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Manufacturing Industry ◽  
Matrix Completion ◽  
Time Frame ◽  
Full Field ◽  
Field Displacement ◽  
Digital Twins ◽  
Median Error ◽  
The Matrix ◽  
Core Components ◽  
Perception Model

Full-field displacement perception and digital twins for core components play a crucial role in the precision manufacturing industry, such as aviation manufacturing. This paper presents a real-time full-field displacement perception method for the combination of online multipoint displacement monitoring and matrix completion theory. Firstly, a conceptual full-field displacement perception model based on the observed information of the multi-points is established. To obtain the full-field displacements of a core component, the component is divided into plentiful discrete points, including observed and unobserved points, based on which the relationship between the observed points and the full-field displacements is established. Then, the solution method of the full-field displacement perception model is proposed. Based on the matrix completion principle and the big data of the simulation, the optimization problem is employed to work out the model and, meanwhile, the pseudo-code is put forward. Finally, the full-field displacement perception experiments are performed. Repeated experiments show that the max error of the displacements calculated by the proposed method can be less than 0.094 mm and the median error can be less than 0.054 mm, while the average time frame can be less than 0.48 s, which is promising considering the high precision and efficiency requirements of the assembly of large aircraft.

scholarly journals MC2: a two-phase algorithm for leveraged matrix completion

2018 ◽  
Vol 7 (3) ◽  
pp. 581-604 ◽  
Author(s):  
Armin Eftekhari ◽  
Michael B Wakin ◽  
Rachel A Ward
Keyword(s):  
Broad Class ◽  
Matrix Completion ◽  
A Priori ◽  
Total Sample ◽  
Second Phase ◽  
Sample Complexity ◽  
Two Phase ◽  
The Matrix ◽  
Leverage Scores ◽  
Uniform Random Sampling

Abstract Leverage scores, loosely speaking, reflect the importance of the rows and columns of a matrix. Ideally, given the leverage scores of a rank-r matrix $M\in \mathbb{R}^{n\times n}$, that matrix can be reliably completed from just $O (rn\log ^{2}n )$ samples if the samples are chosen randomly from a non-uniform distribution induced by the leverage scores. In practice, however, the leverage scores are often unknown a priori. As such, the sample complexity in uniform matrix completion—using uniform random sampling—increases to $O(\eta (M)\cdot rn\log ^{2}n)$, where η(M) is the largest leverage score of M. In this paper, we propose a two-phase algorithm called MC2 for matrix completion: in the first phase, the leverage scores are estimated based on uniform random samples, and then in the second phase the matrix is resampled non-uniformly based on the estimated leverage scores and then completed. For well-conditioned matrices, the total sample complexity of MC2 is no worse than uniform matrix completion, and for certain classes of well-conditioned matrices—namely, reasonably coherent matrices whose leverage scores exhibit mild decay—MC2 requires substantially fewer samples. Numerical simulations suggest that the algorithm outperforms uniform matrix completion in a broad class of matrices and, in particular, is much less sensitive to the condition number than our theory currently requires.

scholarly journals Mortality Risk and The Progression of The Electronic Frailty Index and Hospital Frailty Risk Score Over Time

2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Joe Hollinghurst ◽  
Alan Watkins
Keyword(s):  
Risk Score ◽  
Frailty Index ◽  
Time Frame ◽  
Time Dependent ◽  
Cox Models ◽  
Hazard Ratios ◽  
Increased Risk ◽  
The Matrix ◽  
Time Dependent Covariates ◽  
Over Time

IntroductionThe electronic Frailty Index (eFI) and the Hospital Frailty Risk Score (HFRS) have been developed in primary and secondary care respectively. Objectives and ApproachOur objective was to investigate how frailty progresses over time, and to include the progression of frailty in a survival analysis.To do this, we performed a retrospective cohort study using linked data from the Secure Anonymised Information Linkage Databank, comprising 445,771 people aged 65-95 living in Wales (United Kingdom) on 1st January 2010. We calculated frailty, using both the eFI and HFRS, for individuals at quarterly intervals for 8 years with a total of 11,702,242 observations. ResultsWe created a transition matrix for frailty states determined by the eFI (states: fit, mild, moderate, severe) and HFRS (states: no score, low, intermediate, high), with death as an absorbing state. The matrix revealed that frailty progressed over time, but that on a quarterly basis it was most likely that an individual remained in the same state. We calculated Hazard Ratios (HRs) using time dependent Cox models for mortality, with adjustments for age, gender and deprivation. Independent eFI and HFRS models showed increased risk of mortality as frailty severity increased. A combined eFI and HFRS revealed the highest risk was primarily determined by the HFRS and revealed further subgroups of individuals at increased risk of an adverse outcome. For example, the HRs (95% Confidence Interval) for individuals with an eFI as fit, mild, moderate and severe with a high HFRS were 18.11 [17.25,19.02], 20.58 [19.93,21.24], 21.45 [20.85,22.07] and 23.04 [22.34,23.76] respectively with eFI fit and no HFRS score as the reference category. ConclusionFrailty was found to vary over time, with progression likely in the 8-year time-frame analysed. We refined HR estimates of the eFI and HFRS for mortality by including time dependent covariates.

The skill needs of the manufacturing industry: can higher education keep up?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Oran Doherty ◽  
Simon Stephens
Keyword(s):  
Higher Education ◽  
Best Practice ◽  
Manufacturing Industry ◽  
Manufacturing Sector ◽  
Rapid Development ◽  
Time Frame ◽  
Manufacturing Companies ◽  
Senior Managers ◽  
Experiential Training ◽  
Content Type

PurposeThis paper explores the implications for higher education of the rapid development in technology used by the manufacturing sector. Higher education programmes change or new courses are introduced in attempts to match labour market demands. However, the pace of change in the manufacturing industry challenges the authors to reconceive how programmes and modules can and should be designed and delivered.Design/methodology/approachThis study is based on interviews with 26 senior management representatives from manufacturing companies in Ireland. The 26 senior managers and their companies represent the wide diversity of Ireland's manufacturing sector. All the interviews were face to face, complimented by a short questionnaire. Follow-up interviews focussed on the emergent findings were carried out to aid the writing of recommendations for the best practice in programme design and delivery.FindingsWhat emerges from this study is that the manufacturing industry needs skills at three distinct levels. The authors define and classify the skill requirements at entry, competent and expert level. The authors place an emphasis on upskilling as an aid to movement between the three levels. In addition, and significantly, the desired time frame for delivery of these skills and/or upskilling is very short.Originality/valueAccelerated reskilling programmes with faster, shorter bursts of work-based learning (WBL) and experiential training are required. With a growing demand for those at competent and expert level, it is necessary to promote WBL to facilitate the upskilling of those employed in manufacturing roles, particularly in small and medium-sized enterprises (SMEs).

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