?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Asset+life+prediction+and+maintenance+decision-making+using+a+non-linear+non-Gaussian+state+space+model&rft.creator=Zhou%2C+Yifan&rft.subject=degradation+model%2C+EM+algorithm%2C+Particle+filter%2C+Particle+smoother%2C+State+space+model%2C+Partially+observable+Markov+decision+process&rft.description=Estimating+and+predicting+degradation+processes+of+engineering+assets+is+crucial+for+reducing+the+cost+and+insuring+the+productivity+of+enterprises.+Assisted+by+modern+condition+monitoring+(CM)+technologies%2C+most+asset+degradation+processes+can+be+revealed+by+various+degradation+indicators+extracted+from+CM+data.+Maintenance+strategies+developed+using+these+degradation+indicators+(i.e.+condition-based+maintenance)+are+more+cost-effective%2C+because+unnecessary+maintenance+activities+are+avoided+when+an+asset+is+still+in+a+decent+health+state.+A+practical+difficulty+in+condition-based+maintenance+(CBM)+is+that+degradation+indicators+extracted+from+CM+data+can+only+partially+reveal+asset+health+states+in+most+situations.+Underestimating+this+uncertainty+in+relationships+between+degradation+indicators+and+health+states+can+cause+excessive+false+alarms+or+failures+without+pre-alarms.+The+state+space+model+provides+an+efficient+approach+to+describe+a+degradation+process+using+these+indicators+that+can+only+partially+reveal+health+states.+However%2C+existing+state+space+models+that+describe+asset+degradation+processes+largely+depend+on+assumptions+such+as%2C+discrete+time%2C+discrete+state%2C+linearity%2C+and+Gaussianity.+The+discrete+time+assumption+requires+that+failures+and+inspections+only+happen+at+fixed+intervals.+The+discrete+state+assumption+entails+discretising+continuous+degradation+indicators%2C+which+requires+expert+knowledge+and+often+introduces+additional+errors.+The+linear+and+Gaussian+assumptions+are+not+consistent+with+nonlinear+and+irreversible+degradation+processes+in+most+engineering+assets.+This+research+proposes+a+Gamma-based+state+space+model+that+does+not+have+discrete+time%2C+discrete+state%2C+linear+and+Gaussian+assumptions+to+model+partially+observable+degradation+processes.+Monte+Carlo-based+algorithms+are+developed+to+estimate+model+parameters+and+asset+remaining+useful+lives.+In+addition%2C+this+research+also+develops+a+continuous+state+partially+observable+semi-Markov+decision+process+(POSMDP)+to+model+a+degradation+process+that+follows+the+Gamma-based+state+space+model+and+is+under+various+maintenance+strategies.+Optimal+maintenance+strategies+are+obtained+by+solving+the+POSMDP.+Simulation+studies+through+the+MATLAB+are+performed%3B+case+studies+using+the+data+from+an+accelerated+life+test+of+a+gearbox+and+a+liquefied+natural+gas+industry+are+also+conducted.+The+results+show+that+the+proposed+Monte+Carlo-based+EM+algorithm+can+estimate+model+parameters+accurately.+The+results+also+show+that+the+proposed+Gamma-based+state+space+model+have+better+fitness+result+than+linear+and+Gaussian+state+space+models+when+used+to+process+monotonically+increasing+degradation+data+in+the+accelerated+life+test+of+a+gear+box.+Furthermore%2C+both+simulation+studies+and+case+studies+show+that+the+prediction+algorithm+based+on+the+Gamma-based+state+space+model+can+identify+the+mean+value+and+confidence+interval+of+asset+remaining+useful+lives+accurately.+In+addition%2C+the+simulation+study+shows+that+the+proposed+maintenance+strategy+optimisation+method+based+on+the+POSMDP+is+more+flexible+than+that+assumes+a+predetermined+strategy+structure+and+uses+the+renewal+theory.+Moreover%2C+the+simulation+study+also+shows+that+the+proposed+maintenance+optimisation+method+can+obtain+more+cost-effective+strategies+than+a+recently+published+maintenance+strategy+optimisation+method+by+optimising+the+next+maintenance+activity+and+the+waiting+time+till+the+next+maintenance+activity+simultaneously.&rft.publisher=Queensland+University+of+Technology&rft.date=2010&rft.type=Thesis&rft.format=application%2Fpdf&rft.relation=https%3A%2F%2Feprints.qut.edu.au%2F41696%2F1%2FYifan_Zhou_Thesis.pdf&rft.rights=free_to_read&rft.relation=Zhou%2C+Yifan+(2010)+Asset+life+prediction+and+maintenance+decision-making+using+a+non-linear+non-Gaussian+state+space+model.+PhD+thesis%2C+Queensland+University+of+Technology.&rft.id_number=https%3A%2F%2Feprints.qut.edu.au%2F41696%2F&rft.identifier=Faculty+of+Built+Environment+and+Engineering