在本篇論文中，我們將展現二無母數的模型，分別為AFT/CE模型以及PH/TFR模型，用來描述在階段性加速壽命實驗中所獲得的資料。並且介紹一無母數的方法可藉由這些資料推測在常態使用下，累積失敗機率的上界及可靠度函數的下界。
這種方法為無母數的方法，即無須假設一特別形式的加速函數，且所推測出來的上界及下界皆為可用所得資料估計出來的值。為檢定模型中所使用的假設正確與否以及實行適合度檢定，我們考慮了一個調整過的特別實驗。
最後，本文亦介紹了一模擬的數值分析例子。

In this paper we present two nonparametric accelerated life testing models, namely the accelerated failure time/cumulative exposure (AFT/CE) and proportional hazards/tampered failure rate (PH/TFR) models, and develop methods for obtaining the confidence bounds for low-stress cumulative failure probabilities and reliability functions, based on data collected from a step-stress accelerated life test. The approach is nonparametric in the sense that most of the functions, especially the damage rate function, involved in these two models do not assume any specific forms, except they satisfy certain verifiable conditions. The obtained upper bounds for the cumulative failure probabilities and lower bounds for the reliability functions under these two models are estimatable from the test data. To provide formal procedures for verifying the conditions of the damage rate function and for testing the goodness-of-fit (GOF) of the proposed models, the traditional step-stress test is slightly modified to obtain necessary data for these purposes so that the proposed procedures can be carried out. We have complete procedures for the AFT/CE model; but only partial results are obtained for the PH/TFR model. Finally, a simulated numerical example is used to illustrate the proposed methods for the AFT/CE model.

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