International Journal of Reliability and Safety (5 papers in press)

Regular Issues

• Pre-chamber spark ignition: a reliability analysis of pre-chamber valve functions  
  by Faraz Akbar, Sarah Zaki 
  Abstract: A pre-chamber ignition allows spark-ignition engines to operate in lean air-fuel settings. It improves fuel efficiency and reduces emissions. In this study, a reliability analysis of a single GE Jenbacher J620 natural gas engine was done. It was operational on continuous load in the power generation sector in Karachi, Pakistan. A bathtub curve of the GE J620 pre-chamber gas valve (PCV) was generated. The three-year industrial data comprised PCV failures that occurred between two overhauls. During infant mortality, the curve revealed 7 failures during 1000 hours. This decreased to a failure for the next two cycles of thousand hours each. There was a 40% decrease in reliability after 1500 hours. Exponential distribution revealed that the mean time-to-failure (MTTF) was 545.5 hours. This study was the first of its kind in the facility. Previously, much time was lost in breakdown maintenance. Thus, it helped to increase the systems reliability.
  Keywords: bathtub curve; exponential distribution; failure rate; fuel injection; gas engine; pre-chamber combustion; pre-chamber spark ignition; pre-chamber valve; probability density function; reliability.
  
  
• Seismic safety evaluation of dam using cloud model  
  by Alabhya Sharma, Shiv Dayal Bharti, Mahendra Kumar Shrimali, Tushar Kanti Datta 
  Abstract: For the preliminary estimate of the seismic safety of the dam, expert opinions are often relied upon. However, expert opinions, when expressed linguistically, are associated with uncertainty and fuzziness. To address this inadequacy, cloud models have been utilized in numerous studies. In the present investigation, a cloud model is employed to predict the seismic safety of a concrete gravity dam. Experts evaluate seismic safety factors of dams, focusing on seismic damage potential, hazard, and structural strength. Each factor has key sub-indicators rated on a five-point scale. Through qualitative-to-quantitative conversion, cloud points are generated for analysis. The coefficient of variation method identifies sub-indicator influences on each factor. Comparing these cloud models to standard ones visually depicts dam safety. Illustrated with Koyna dam, this approach reveals its seismic safety below normal range, showcasing the effectiveness of the three indicators in assessing dam safety.
  Keywords: cloud model; dam seismic safety assessment; Koyna dam; correlation coefficient method; risk assessment.
  DOI: 10.1504/IJRS.2025.10069925
   
  
• Testing scenario generation and selection for autonomous vehicles using an integrated approach based on real-world accident data  
  by Guozheng Song, Xiaopeng Li 
  Abstract: The safety and reliability of Autonomous Vehicles (AVs) is a core concern, which should be validated before application. The critical testing scenarios extracted from historical accidents of AVs can help achieve the efficient safety and reliability testing of AVs. This paper presents an integrated approach that combines a data-driven method with a Bayesian Network (BN). The information including states, states' occurrence likelihoods and quantitative relationships of variables related to scenarios are learned from an AV accident database of California Department of Motor Vehicles (DMV), which is applied to establish a BN. Then the scenarios are generated and assessed with the BN and a severity matrix. The testing scenarios are selected based on their weighted consequence severity and risk. In this way, this work achieved critical testing scenarios for the automated driving systems (ADSs) and perception systems (PSs) of AVs based on the AV accident database.
  Keywords: autonomous vehicle; Bayesian network; testing scenario generation and selection.
  DOI: 10.1504/IJRS.2024.10070893
   
  
• Fatigue in the Indonesian palm oil industry: a critical review  
  by Taufiq Ihsan, Vioni Derosya 
  Abstract: The palm oil industry in Indonesia is a major contributor to global oil and fat production, employing millions of workers. Despite its vast workforce, there is a significant lack of information regarding worker fatigue. This review highlights critical fatigue-related issues in Indonesian palm oil plantations. We conducted a comprehensive literature review, gathering publications addressing fatigue risk factors, short-term and long-term health and safety consequences, and various fatigue mitigation strategies. Working in oil palm plantations exposes individuals to multiple fatigue-inducing factors. These factors not only lead to immediate effects like reduced cognitive function and accidents but also contribute to chronic illnesses. It is crucial to evaluate the effectiveness of existing legislation and industry practices while optimizing working, living, and sleeping conditions. Considering the current workplace conditions, a thorough assessment of potential preventive measures, including fatigue prediction tools and personalized fatigue management systems, is recommended.
  Keywords: mitigation strategies; palm oil; risk factors; worker fatigue.
  DOI: 10.1504/IJRS.2025.10072246
   
  
• Improving the accuracy of drowning detection based on improved YOLOv5  
  by Kaikai Wang, Ruiliang Yang, Libin Yang 
  Abstract: Drowning stands as a primary cause of unintentional deaths globally. This paper presents an improved YOLOv5 algorithm tailored for drowning detection, aiming to effectively mitigate drowning incidents. The improved YOLOv5 incorporates the Ghost-CBAM-C3 (GCC) module, which comprises Ghost-bottleneck modules and the CBAM module, and the learning rate decay of Cosine Annealing. To gauge the algorithm's efficacy, four self-made datasets were curated utilizing a DJI mini3pro drone over both swimming pools and natural water bodies. Experimental findings underscore the heightened performance of the improved YOLOv5 over the original YOLOv5s. This enhancement manifests in a precision boost from 92.8% to 97.1 %, and the values for mean average precision (mAP@0.5), weights, and the frames-per-second (FPS) are 93.2, 14.1, and 23.70, respectively, affirming its applicability in real-time scenarios. Furthermore, results indicate superior performance of the swimming pool dataset compared to those from natural water bodies.
  Keywords: drowning detection; improved YOLOv5; self-made datasets; CBAM; safety; drone; LabelImg software; k-means; SPPF; Ghost module.
  DOI: 10.1504/IJRS.2024.10072350