One way of obtaining information about reliability of units is to accelerate their life by testing at higher levels of stress (such as increasing elevated temperatures or voltages). Predicting the lifetime of a unit at normal operating conditions based on data collected at accelerated conditions is a common objective of these tests. Different models of accelerated life testing are used for such extrapolations. Two statistical based models are widely used: parametric models which require a prior specified lifetime distribution, and nonparametric models that relax of the assumption of the life time distribution. The proportional odds model is a nonparametric model in accelerated life testing based on the odds function and show that it gives a more accurate reliability estimates than proportional hazard model. This paper will concentrate on the models of proportional odds nonparametric accelerated life test for reliability prediction.
The study of springs Abu-Aljeer natural asphalt at proven of al-anbar (Iraq), to find a mean of exploiting the asphalt springs as alternative energy resource, Included two stages The first: Separation the components of asphalt in two ways the first is column chromatography and second represented by extraction- chromatography. The results of separation were 10.20% Asphltene, 89.18% Maltene which separated lately to (Paraffinic 45.23%, Aromatic 28. 39% and Resin 21.66%). The second: Trying to improve the asphalt specifications by using natural materials that are available locally (limestone) with (5, 15, 25, 35%), which have given good results. Rheological properties have been tested, in such average that (virgin Softening was 430C, became 560C, Penetration was 110 dropped 39 and viscosity was 11355 turnedy other 47231cent-Stok, mm2Sec), and flash point ( 1790 C became 200 0C), Fractionated parts of asphalt were characterized by (UV), (FT-IR) spectra. This study also clarified paraffin compounds which represent the main part material and the colloidal state is in Gel phase.