Reliability Assessment and Cost Optimization of a Fault-Tolerant Rice Processing System under Environmental Disturbances

Abstract

Modern industries heavily depend on automated and semi-automated production units, where uninterrupted operation is crucial to meeting market demand and maintaining grain quality. However, such systems are exposed not only to internal component failures but also to environmental disturbances such as humidity, temperature fluctuations, dust, and power-quality variations. This paper develops a comprehensive reliability and cost optimization model for a four-unit rice industry system operating under a fault-tolerant framework with standby support. An additional environmental error stage is explicitly incorporated into the state transition diagram to capture real-world operating conditions. The system behaviour is modelled as a continuous-time Markov process with lacking fault exposure, restart mechanism, and repair capacity subject to service interruption. Transient state probabilities are derived using Laplace transform and matrix-analytical techniques. Key performance indicators, including Mean Time to Failure, system reliability, availability and Average number of component failures, are evaluated. A Cost-effective ratio (CER) is further formulated by combining operational, repair, environmental recovery, and downtime costs. Numerical illustrations demonstrate how environmental disturbance intensity and maintenance parameters influence system performance. The results show that integrating fault-tolerant design with environmental recovery strategies significantly improves operational reliability while reducing long-term system cost in rice processing industries.