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Validation methodology for distribution-based degradation model

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Journal of Systems Engineering and Electronics 2012年第4期23卷 553-559页

作者： Yunxia Chen Zhiguo Zeng Rui Kang School of Reliability and Systems Engineering Beihang UniversityBeijing 100191E R.China

Distribution-based degradation models （or graphical approach in some literature） occur in a wide range of applications. However, few of existing methods have taken the validation of the built model into consideration. A validation methodology for distribution-based models is proposed in this paper. Since the model can be expressed as consisting of assumptions of model structures and embedded model parameters, the proposed methodology carries out the validation from these two aspects. By using appropriate statistical techniques, the rationality of degradation distributions, suitability of fitted models and validity of degradation models are validated respectively. A new statistical technique based on control limits is also proposed, which can be implemented in the validation of degradation models＇ validity. The case study on degradation modeling of an actual accelerometer shows that the proposed methodology is an effective solution to the validation problem of distribution-based de qradation models.

关键词： degradation model distribution-based degradationmodel graphical method model validation control limits.

Validation Metric of degradation model with Dynamic Performance

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Journal of Shanghai Jiaotong university(Science) 2015年第3期20卷 302-306页

作者：阳纯波曾声奎郭健彬 School of Reliability and Systems Engineering Science and Technology on Reliability and Environment Engineering Laboratory Beihang University

With more and more attention on degradation process, we need the degradation model to be accurate all over the time rather than only at some specific moments. However, the traditional validation metric only estimates difference of static features. A validation method proposed in this paper uses hypothesis testing to identify whether the distributions of experimental measurements and simulation results are consistent. Then, based on the deviation between sample means, a global validation metric which reflects the difference of degradation process between computational model and physical system all over the service time is derived from the statistics of deviation between sample means. Furthermore, curve fit method for discrete experimental measurements is introduced. The case of electro-hydraulic servo valve is studied, and the results show that the proposed validation metric is appropriate for the validation of degradation model with dynamic performance output.

关键词： validation degradation model dynamic performance

Multi-objective structural optimization and degradation model of magnesium alloy ureteral stent

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Medicine in Novel Technology and Devices 2024年第2期22卷 19-28页

作者： Lin Zhu Qiao Li Yuanming Gao Lizhen Wang Yubo Fan Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education Beijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijing100083China School of Engineering Medicine Beihang UniversityBeijing100191China

Background:Mg alloys have attractive properties,including biocompatibility,biodegradability,and ideal mechanical ***,Mg alloys are regarded as one of the promising candidates for manufacturing ureteral *** study proposed a multi-objective optimization method based on the Kriging surrogate model,NSGA-III,and finite element analysis to improve the degradation performance of Mg alloy ureteral ***:The finite element model for the degradation of Mg alloy ureteral stents has been established to compare the degradation performance of the stents under different *** hypercube sampling was adopted to generate train sample points in the design ***,the Kriging surrogate model was constructed between strut parameters and stent degradation *** NSGA-III was utilized to determine the optimal solution in the global design ***:The optimized stent achieved 5.52degradation uniformity(M),10degradation time(DT),and 4work time(FT).The errors between the Kriging surrogate model and the finite element calculation results were less than 6%.Conclusion:The optimized stent achieved better degradation *** degradation behavior of stents was dependent on the design *** multi-objective optimization method based on the Kriging surrogate model and finite element analysis was effective in stent design optimization problems.

关键词： Mg alloys ureteral stent Kriging surrogate model NSGA-III Multi-objective optimization degradation model

Stochastic process-based degradation modeling and RUL prediction: from Brownian motion to fractional Brownian motion

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Science China(Information Sciences) 2021年第7期64卷 5-24页

作者： Hanwen ZHANG Maoyin CHEN Jun SHANG Chunjie YANG Youxian SUN School of Automation and Electrical Engineering University of Science and Technology Beijing State Key Laboratory of Industrial Control Technology College of Control Science and EngineeringZhejiang University Department of Automation Tsinghua University School of Automation and Electrical Engineering Linyi University Department of Electrical and Computer Engineering University of Alberta

Brownian motion(BM) has been widely used for degradation modeling and remaining useful life(RUL) prediction, but it is essentially Markovian. This implies that the future state in a BM-based degradation process relies only on its current state, independent of the past states. However, some practical industrial devices such as Li-ion batteries, ball bearings, turbofans, and blast furnace walls show degradations with long-range dependence(LRD), where the future degradation states depend on both the current and past degradation states. This type of degradation naturally brings two interesting problems, that is, how to model the degradations and how to predict their RULs. Recently, in contrast to the work that uses only BM, fractional Brownian motion(FBM) is introduced to model practical degradations. The most important feature of the FBM-based degradation models is the ability to characterize the non-Markovian degradations with LRD. Although FBM is an extension of BM, it is neither a Markovian process nor a semimartingale. Therefore, how to obtain the first passage time of an FBM-based degradation process has become a challenging task. In this paper, a review of the transition of RUL prediction from BM to FBM is provided. The peculiarities of FBM when addressing the LRD inherent in some practical degradations are discussed. We first review the BM-based degradation models of the past few decades and then give details regarding the evolution of FBM-based research. Interestingly, the existing BM-based models scarcely consider the effect of LRD on the prediction of RULs. Two practical cases illustrate that the newly developed FBMbased models are more generalized and suitable for predicting RULs than the BM-based models, especially for degradations with LRD. Along with the direction of FBM-based RUL prediction, we also introduce some important and interesting problems that require further study.

关键词： remaining useful life degradation model Brownian motion fractional Brownian motion long-range dependence

Artificial woodland degradation in semi-arid agro-pastoral transitional area： conceptual model and status assessment

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Journal of Forestry Research 2006年第3期17卷 193-196页

作者： YANG Xiao-hui CI Long-jun ZHANG Ke-bin Research Institute of Forestry Chinese Academy of Forestry Key Laboratory of Tree Breeding and Cultivation State Forestry Administration Beijing 10091 P. R. China College of Soil and Water Conservation Beifing Forestry University Beijing 100083 P. R. China

Planting trees was used as one of cost-effective measures for desertification control in add and semi-add areas of China. Woodland degradation, however, is becoming an inevitable issue in these areas. In this paper, a typical county, Ejin Holo County, Inner Mongolia, China was selected for its assessment of artificial woodland degradation. A conceptual model for woodland degradation was delineated qualitatively based on field sampling survey, and four model-based indicators as humidity index （HI）, vegetation index （NDVI）, soil type （ST） and soil erosion modulus （EM） were screened out and used to a GIS-based method for artificial woodland degradation assessment in this semi-add agro-pastoral transitional area. All the indicator layers were overlaid and desertification assessed using simplified equation with equal weights for each indicators. The assessment results showed that in 336. 09 km^2 of total woodland area, 311.35 km^2 woodland were under degradation, and the area for slight, medium, severe degradation was 78.97, 119.73 and 112.65 km^2, respectively. It was suggested that much attention should be paid on woodland improvement and plant species selection, especially shrub species, before revegetation in similar areas.

关键词： Artificial woodland degradation model GIS degradation assessment, Semi-arid area

Strength degradation of Wood Members Based on the Correlation of Natural and Accelerated Decay Experiments

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Journal of Renewable Materials 2020年第5期8卷 565-577页

作者： Xueliang Wang Qiangang Xu Xiuxin Wang Junhui Guo Wancheng Cao Chun Xiao Hubei Key Laboratory of Roadway Bridge&Structure Engineering Wuhan University of TechnologyWuhan430070China School of Chemistry Chemical Engineering and Life SciencesWuhan University of TechnologyWuhan430070China School of Automation Wuhan University of TechnologyWuhan430070China

An accelerated decay test and a natural decay test were conducted synchronically to explore the strength degradation of decaying wood members under long-term exposure to natural environment.A natural decay test was carried out to measure the bending strength,compressive strength parallel to grain and modulus of elasticity of the wood members,with 6 groups of specimens decayed in natural environment for 3 to 18 months *** compare with corresponding decay test,in which 6 other groups of specimens were measured under accelerated *** experimental data collected were evaluated by Pearson productmoment for the *** results indicate that the mechanical properties of the accelerated decay were highly correlated with those in natural environment,both of which decreased in the same *** the given test conditions,the mean value of the accelerated decay test data were curve-fitted to achieve the time-dependent degradation model of the bending strength,the compressive strength parallel to grain,as well as the modulus of *** to the high correlation,the acceleration shift factors(ASF)of the two tests were derived,where the bending strength of 2.934,the compressive strength parallel to grain of 2.519 and the elastic modulus of 2.346 were employed to formulate the strength degradation models in the long-term natural *** results verify that the exponential functionσ=σ0e^(-βt)enables to exactly capture the degradation of the mechanical properties of wood members decayed in natural environment.

关键词： Wood member accelerated decay test natural decay test correlation analysis degradation model

Research on the Application of Super Resolution Reconstruction Algorithm for Underwater Image

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Computers, Materials & Continua 2020年第3期62卷 1249-1258页

作者： Tingting Yang Shuwen Jia Hao Ma University of Sanya Sanya572000China 1455 Boulevard de Maisonneuve O MontréalQC H3G 1M8Canada

Underwater imaging is widely used in ocean,river and lake exploration,but it is affected by properties of water and the *** order to solve the lower-resolution underwater image formed by the influence of water and light,the image super-resolution reconstruction technique is applied to the underwater image *** paper addresses the problem of generating super-resolution underwater images by convolutional neural network framework *** research the degradation model of underwater images,and analyze the lower-resolution factors of underwater images in different situations,and compare different traditional super-resolution image reconstruction *** further show that the algorithm of super-resolution using deep convolution networks(SRCNN)which applied to super-resolution underwater images achieves good results.

关键词： Underwater image image super-resolution algorithm algorithm reconstruction degradation model

Predicting localised corrosion and mechanical performance of a PEO surface modified rare earth magnesium alloy for implant use through in-silico modelling

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Bioactive Materials 2023年第8期26卷 437-451页

作者： Kerstin van Gaalen Conall Quinn Marek Weiler Felix Gremse Felix Benn Peter E.McHugh Ted J.Vaughan Alexander Kopp Biomechanics Research Centre(BioMEC) Biomedical EngineeringSchool of EngineeringUniversity of GalwayGalwayIreland Meotec GmbH AachenGermany Institute for Experimental Molecular Imaging RWTH Aachen UniversityAachenGermany Gremse-IT GmbH AachenGermany School of Mechanical and Aerospace Engineering Queen’s University BelfastBelfastUnited Kingdom

In this study,the influence of a plasma electrolytic oxidation(PEO)surface treatment on a medical-grade WE43-based magnesium alloy is examined through an experimental and computational framework that considers the effects of localised corrosion features and mechanical properties throughout the corrosion ***,a comprehensive in-vitro immersion study was performed on WE43-based tensile specimens with and without PEO surface modification,which included fully automated spatial reconstruction of the phenomenological features of corrosion through micro-CT scanning,followed by uniaxial tensile *** the experimental data of both unmodified and PEO-modified groups were used to calibrate parameters of a finite element-based surface corrosion ***-vitro,it was found that the WE43-PEO modified group had a significantly lower corrosion rate and maintained significantly higher mechanical properties than the *** corrosion rates were~50%lower in the WE43-PEO modified specimens,the local geometric features of corroding surfaces remained similar to the unmodified WE43 group,however evolving after almost the double amount of *** were also able to quantitatively demonstrate that the PEO surface treatment on magnesium continued to protect samples from corrosion throughout the entire period tested,and not just in the early stages of *** the results from the testing framework,the model parameters of the surface-based corrosion model were identified for both *** enabled,for the first time,in-silico prediction of the physical features of corrosion and the mechanical performance of both unmodified and PEO modified magnesium *** simulation framework can enable future in-silico design and optimisation of bioabsorbable magnesium devices for load-bearing medical applications.

关键词： Plasma electrolytic oxidation WE43MEO degradation model Corrosion phenomenology Mechanical integrity

Photolytic model of Six Degradable Mulch Plastic Films

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Agricultural Science & Technology 2012年第6期13卷 1342-1345,1358页

作者：温善菊伍维模魏建军战勇支金虎彭杰陈源塔里木大学植物科学学院新疆阿拉尔843300 新疆农垦科学院作物所新疆石河子832000

[Objective] This study aimed to solve the mulch plastic film pollution problems in Xinjiang, in order to provide reliable theoretical basis for the research on the degradation mechanism of biodegradable plastic films. [Method] The effect of illumination intensity on the decomposition of decomposable mulching films was investigated through simulating the field condition in laboratory. Regression analysis was employed to fit the processes of film decompositions. [Result] The weight loss ratios of different types of plastic films were closely related with the illumination. There was no sundry produced during the degradation process, but the weight was reduced, indicating that degradation produced gas, thus, ultraviolet rays had destructive effect on mulch plastic films. Different types of plastic films showed significant differences in the degradation speeds, and under the same conditions, the degradation speed of S4# with the induction period of 30 d was the fastest. With the extension of uv illumination time, the degradation became cumulative degradation process. [Conclusion] Under the uv rays, the weight loss ratio and illumination hours is regarded as a positive correlation relationship. The significant inspection shows that the data fitted degradation model can be described by the logistic model of Y = a/（1＋b×e -ct）, and all the parameters show significant differences （P0.01）.

关键词： Degradable plastic Weight loss Ultraviolet radiation Induction period degradation model