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1. 1. Essays on the Assumption of Proportional Hazards in Cox Regression

   Författare :Inger Persson; Kenneth Carling; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Informatics; computer and systems science; Proportional hazards; Cox regression; Proportionality assumption; Informatik; data- och systemvetenskap; Informatics; computer and systems science; Informatik; data- och systemvetenskap; statistik; Statistics;

   Sammanfattning : This thesis consists of four papers about the assumption of proportional hazards for the Cox model in survival analysis. The first paper compares the hazard ratio estimated from the Cox model to an exact calculation of the geometric average of the hazard ratio when the underlying assumption of proportional hazards is false, i.e. LÄS MER

3. 2. Evaluation and Mitigation of Industrial Fire Hazards

   Författare :Petra Andersson; Avdelningen för Brandteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Teknik; Technological sciences; Effect of fires; Accidental release; Water mist; Halon replacement; Industrial Fire Hazards; Human burns; Smoke detektion;

   Sammanfattning : A tool suitable for conducting industrial fire and explosion hazard analysis is presented, together with an identification of weak links in the hazard evaluation chain. For some of the weak links additional research has been carried out. LÄS MER

4. 3. The Analysis of Duration and Panel Data in Economics

   Författare :Wolfgang Hess; Nationalekonomiska institutionen; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Monetary Exchange Rate Model; Homogeneity Testing; Panel Cointegration; Pooling; Duration of Trade; Unemployment Duration; Proportional Hazards; Unobserved Heterogeneity; Hazard Rate; Discrete-Time Duration Model; Threshold Excess Model;

   Sammanfattning : This thesis is divided into two distinct parts. The first part contains three chapters dealing with the analysis of duration data from an econometric perspective and with application to trade durations. LÄS MER

5. 4. Applications of the PEXE-concept for maintenance policies and proportional hazards models

   Författare :Ulf Westberg; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Kvalitetsteknik; Quality Technology and Management;

   Sammanfattning : .... LÄS MER

7. 5. Cost optimization of maintenance scheduling for wind turbines with aging components

   Författare :Quanjiang Yu; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Integer linear optimization; Age-based preventive maintenance scheduling; Renewal-reward theorem; Weibull distribution; Combinatorial optimization; Wind turbine maintenance; Virtual replacement; Condition monitoring data; Cox proportional hazards method; Linear programming;

   Sammanfattning : A major part of the wind turbine operation cost is resulted from the maintenance of its components. This thesis deals with the theory, algorithms, and applications concerning minimization of the maintenance cost of wind power turbines, using mathematical modelling to find the optimal schedules of preventive maintenance activities for multi-component systems. LÄS MER