Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Mechanical and Aerospace Engineering

Committee Chair

Arvind Thiruvengadam

Committee Co-Chair

Marc Besch

Committee Member

Marc Besch

Committee Member

V’yacheslav Akkerman


egulatory agencies have taken several measures to ensure proper regulation of engine exhaust in response to a yearly rise in urban pollution levels. This is due in no small part to vehicular traffic and resulting air pollution from exhaust.

This study evaluates the NOx Control Performance Tracking (NCPT) Onboard Diagnostic (OBD) parameter proposed by the California Air Resources Board (CARB) as a tool to assess in-use heavy-duty vehicle performance. It also assesses the various criteria prescribed in the NCPT approach for applicability to real-world vehicle data.

In order to analyze the data, the study also investigated the effect of various filter constants values over the cumulative values binned into the various categories. The study also illustrates the differences in the bin statistics as a function of vehicle activity and it evaluates the applicability of the NCPT approach for evaluating Not-to-Exceed (NTE) operation. The collected data displayed abnormalities which could be attributed to sensor limitations. This project proposes two options to reduce the noise in the sensor’s data. In the first, it uses the NOx stable channel – if available – and the second is the exponentially weighted moving average (EWMA). Both reducing methods were then compared to the original raw dataset to ensure no over smoothing of the data occurred. Once these datasets were finalized, they went through the Moving-Average Window (MAW) method proposed by EURO VI regulations before they could be binned.

The results indicate that despite applying different methods for NOx data reduction, the final binning product only displayed small change in value for certain bins while some remained intact. In addition, the vehicle displayed very few values inside the NTE zone, accounting at the most for 17% of the engine’s operation.