Browsing by Author "Yucesan, Ongun"

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Impact of Operations on a Series Per Reliability Perspective
(2025) Yucesan, Ongun; Avionics; 13. School of Civil Aviation (4-Year); 01. Atılım University
The Mean Time Between Failure (MTBF) figures are the average of test durations between failure observations formed into a series. They can be seen to suit classical statistical distributions. An equally possible condition is that they are not stationary as a contradiction to the previous statement. In such worse conditions accepting availability of a concealed statistical property, this paper tries to identify the impact of Bi-sample Differencing and Bi-sample mean manipulations. In other words, operating on reliability observations series to reveal concealed statistical knowledge. Experimentation based on observation over a stationary series as a controlled experiment. As an outcome of experiments, the differencing seems to be alleviating the trend and seasonality to a degree. The bi-sample averaging is observed to be hiding variant conditions.
On Stationarity of Variance Calculation Series
(2023) Yucesan, Ongun; Avionics; 13. School of Civil Aviation (4-Year); 01. Atılım University
While making reliability observations, more samples mean one can make a statistically representative prediction. It is possible to model the failure arrival characteristics statistically using this knowledge. As a natural product of many experiments, a mean and variance figure can be identified for modelling the different occurrences. Even though the different situations can be modelled with such parameters, it may not wholly outline the condition of the product being developed and under test. The variance calculation series derived from the original reliability observation series, which is normally used for simple variance calculation, can be an important consideration. This consideration is rarely encountered. With a mean and a variance figure, a statistical prediction can be made. However, with the very same parameters, another reliability characteristic possessing product or a subcomponent may exist. For this instance, identifying whether the variance calculation series has stationarity and incorporating it in calculations can yield a possible prediction of a more accurate statistical model. In this study, the variance calculation series is considered for their stationary character at hand and is shown to possess such character yielding further modelling possibilities and emphasizing the importance of this consideration.
Öz Bağlanım Denklem Tahmini ile Durağanlık Testi: Bir Endüstriyel İşletişim Örneği
(2022) Yucesan, Ongun; Özkil, Altan; Aviation Management; Avionics; 13. School of Civil Aviation (4-Year); 01. Atılım University
AR ve ARMA tahminleri, eldeki bir seri için temel bir matematiksel ifadeyi belirlemek açısından iyi bilinen araçlar olmaya devam etmektedir. Matematiksel bir denklem elde edildiğinde, girdi ve çıktı arasında bir transfer fonksiyonu türetmek mümkündür. Bu transfer fonksiyonunun kutupları birim çemberin üzerinde veya dışında yer alıyorsa, üretilen seri durağan olmayacaktır. Önemli sayıda numunenin üretildiği böyle bir seri, bir simülasyon etkinliği için tamsayı taşmalarına neden olacaktır. Çalışma için, Hatalar Arası Ortlama Zaman (HAOZ) gözlem amaçlı doğrulama serisi, bir Endüstriyel Gömülü PC İletişimi Sınama yatağından alınmıştır. Bunlar zaman ve sıklık açısından AR ve ARMA tarafından tahmin edilenlerle karşılaştırılır. AR tahmini, durağan özelliği koruyan 57 derecelik bir polinom durumunda, orijinal gözlemle daha iyi bir eşleşmeye sahiptir.
Time Complexity Comparison of Stopping at First Failure and Completely Running the Test
(Springer, 2020) Yucesan, Ongun; Ozkil, Altan; Aviation Management; Avionics; 13. School of Civil Aviation (4-Year); 01. Atılım University
For a given test set, we compare two test application techniques, "stopping at first failure" and "complete run", respectively. The former stops the test whenever a failure is encountered. The latter however, carries on till the end. Our comparison concludes that although the first technique is generally faster, there is no strong evidence to support a complete rejection of the second technique for it provides statistics useful in test planning. Results support an interchangeable application of both techniques with more frequent use of stopping at first failure. Even though there are numerous studies to decide how to prioritize and select test cases (TC), or to examine dependencies of TCs and codes, the presented comparison of the two test application techniques for a given "test set" has the potential to reduce the total run time of the test.