Applications of the Sojourn - Time Problem to Reliability
The sojourn-time problem of Takáes can be applied to reliability theory. This note reviews Takács' results and applies them to redundant systems, cumulative damage, and a system under non-homogeneous operating conditions.
Some aspects of damage models
Abstract Four stochastic failure models are proposed and their characteristics are discussed. It is considered that an item is subject to shocks. It is assumed that an interval of the time between successive shocks is a random variable and an amount of damage produced by a shock is also a random variable. Of our concern is the total amount of damage in which an amount of damage is additive except Model 4. Then of our interest are the following; (i) the distribution of the total amount of damage at time t , (ii) the mean total amount of damage at time t , (iii) the distribution of the time to failure of an item, where we assume that failure of an item occurs if the total amount of damage exceeds a threshold level, (iv) the mean time to failure of an item, and (v) the failure rate. This paper derives such quantities above for each model. It also shows an example with all exponential assumptions for each model.
Study of Biogas for Power Generation at Pesantren Saung Balong Al-Barokah, Majalengka, West Java
Utilization of biogas from cow manure as a fuel alternative for power plants is done through an anaerobic process. A pilot plant with biogas production of 7 m 3 /day has been installed at Pesantren Saung Balong. Biogas is used for everyday purposes such as cooking and lighting, and used as pure biogas with 2.500 Watt scale generator. Biogas produced with the rate of 0.080 m 3 /hr. Biogas produced during the measurement (450 minutes) is 0.604 m 3 . With these data it is predicted that within a day (24 hours) biogas which can be generated is equal to 1.92 m 3 . Meanwhile, consumption of biogas to the generator with 1.047 W load is 0.019 m3/minutes, the generator will operate for approximately 101.05 minutes or 1.68 hours. Thus electricity that can be saved is 1.759 kWh per day or 52.77 kWh per month and electricity cost that can be saved that is equal to Rp.40.896/month.