Estimation of the reliability for repairable system after maintenance actions is usually based on mathematical models, which can be classified as parametric and non-parametric models where the parametric model is required a prior specified life time distribution while Non-parametric model is that relaxes of the assumption of the life time distribution. Nonparametric life time models are including proportional hazard model and proportional odd model. In this paper we develop repairable reliability model concentrate on generalized repairable model that indicate the mixture of proportional hazard model and proportional odd model. A proportional hazard-proportional odds (PH-PO) model for the purpose of to improve the repairable reliability to obtain accurate estimates of reliability for repairable industrial boiler system at normal operating conditions depending on transformation parameter for reliability prediction for repairable system that represent Beji industrial boiler in power plant. The results show the odd model better than hazard model for repairable system after preventive maintenance depends on time to repair where transformation parameter (c) equal 0.0525094 it is closer to odds model than hazard model. In addition, reliability industrial boiler in case without temperature effect is better than reliability with temperature effect by using exponential model where we note that the reliability at 500 it is worse state where degrade more than (400,450) .
Photovoltaic cells are one of the renewable energy sources that have been employed to produce electrical energy from solar radiation falling on them, but not all incident radiate will produce electrical energy, part of those radiate cause the panel temperature to rise, reducing its efficiency and its operational life, unless an attempt is made to employ one of the traditional cooling methods or innovating other methods to cooling it to reduce this effect, which it represented in the active and passive cooling method. In fact, it is difficult to compare the active method with the passive method, as each method has its Advantages and disadvantages that may suit one region without another. But in general, there are basic factors through which at least a comparison between the two methods can be made. Relatively the passive method is less expensive, in addition to no need for additional parts such as pumps and controllers, there is no energy consumption because it does not require power. But it is less effective and efficient than the active method, while the active method has the ability to disperse the heat higher than the passive method. However, it necessitates the use of electricity and is frequently costlier than the passive strategy. In this review, the most common active and passive cases were reviewed, and the pros and cons of each case are summarized in discussion due to the difficulty to list them. The review recommends that future studies should focus on active water cooling and heat-sink, both of which are viable cooling strategies.