International Journal of Reliability and Safety (3 papers in press)

Regular Issues

• Time-varying reliability analysis method for micropolar fluid elastohydrodynamic lubrication  
  by Yourui Tao, Mingyang Dai 
  Abstract: Reliable lubrication of sliding bearings means that the roller and bearing are separated by the oil film, resulting in less wear and longer life. During the bearing lubrication process, some particle impurities are produced due to wear and other reasons. Generally, the particle size in the micropolar fluid gradually increases with time. Moreover, velocity and load of bearing are uncertain. Therefore, it is very important to consider the time-varying reliability of bearing lubrication. In this paper, a time-varying reliability analysis method for micropolar fluid elastohydrodynamic lubrication is proposed based on response surface method and first passage method. The response surface method is applied to construct the response function of minimum oil film thickness, and the reliability model of lubrication is developed by the film thickness ratio. Then, the reliability of lubrication is calculated by the first passage method. The numerical results show that both the accuracy and efficiency of the proposed method are high.
  Keywords: micropolar fluid; lubrication reliability; response surface method; first passage method.
  
  
• Reducing uncertainty and obtaining superior performance by segmentation based on algebraic inequalities  
  by Michael Todinov 
  Abstract: The paper demonstrates for the first time uncertainty reduction and superior performance through segmentation based on algebraic inequalities. Meaningful interpretation of algebraic inequalities has been used for generating new knowledge in unrelated application domains. Thus, the method of segmentation through an abstract inequality led to a new fundamental theorem related to electrical circuits. The power output from a source with particular voltage, on elements connected in series, is smaller than the total power output from the segmented sources applied to the individual elements. Segmentation attained through the same abstract inequality led to another fundamental theorem related to electrical capacitors. The energy stored by a charge of given size on a single capacitor is smaller than the total energy stored in multiple capacitors with the same equivalent capacity, by segmenting the initial charge over the separate capacitors. Finally, inequalities based on sub-additive and super-additive functions have been introduced for reducing uncertainty and obtaining superior performance by a segmentation or aggregation of controlling factors. By a meaningful interpretation of sub-additive and super-additive inequalities, superior performance and important properties have been established for processes described by a power-law dependence.
  Keywords: segmentation; aggregation; algebraic inequalities; uncertainty reduction.
  
  
• Development and application of a novel hybrid occupational risk assessment model  
  by Muhammet Gul 
  Abstract: Occupational risk assessment (ORA) is so crucial for safety management in the weapons industry since numerous hazards that lead to human causalities may occur. Therefore, occupational health and safety stakeholders suggest proactive approaches in reducing risks to an acceptable level. Therefore, this paper aims to develop a novel hybrid occupational risk assessment model and make its application in the weapons industry. The approach merges TODIM with Fine-Kinney risk analysis concept. Risk parameters used in traditional Fine-Kinney method are weighted by fuzzy Analytic Hierarchy Process (FAHP). Then, hazards and associated risks are quantitatively evaluated and prioritised using this developed approach. To illustrate the approach, processes of the gun and rifle assembly line of a weapons factory in Turkey are handled. The application is carried out to improve operational safety and protect employee health. The theoretical contributions of the approach are twofold: (1) it considers importance weights of Fine-Kinney parameters in risk analysis; (2) it ranks risks where the characteristics of Fine-Kinney, FAHP and TODIM either individually or in integrated style can handle the evaluations in occupational risk assessment problem. On the other side, it benefits practice by improving the overall safety level of the gun and rifle assembly line of the observed factory by suggesting potential action plans.
  Keywords: risk assessment; Fine-Kinney; FAHP; TODIM; weapons industry.