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Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

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Data<br />

Fig. 33. Segment Merging<br />

In addition, options are provided to modify the head and/or tail of the composite cycle so that it may<br />

start and end at zero speed. This is accomplished by adding short start-stop segments that are found<br />

within the data segments themselves. This permits the generation of a typical duty cycle which<br />

begins and ends with the vehicle at zero speed but is synthesized from data available in the data set.<br />

Fig. 34 illustrates the merging of data corresponding to a previously observed stop, with the tail of the<br />

final record. The dotted pink ovals highlight the vehicle speeds in the regions to be overlapped. The<br />

dotted red oval on the left shows the part of the distribution that will become the tail of the record on<br />

the right; where the other dotted red oval is located. The solid ovals at the bottom show the results.<br />

The last component of the DCGenT is synthetic cycle-maker tool. This tool first computes<br />

histograms of speed and acceleration of a driving cycle of arbitrary time-length, and subsequently<br />

attempts to synthesize a driving cycle of a user-specified time-length with similar histograms of speed<br />

and/or acceleration. Some of the different options available are illustrated using a standard driving<br />

cycle, FUDS, as input to DCGenT. The associated outputs are shown in Fig. 35 to Fig. 39.<br />

Fig. 35 shows the input driving cycle (FUDS) and its speed and acceleration statistics in the <strong>for</strong>m of<br />

histograms. The Federal Urban Driving Schedule (FUDS) is shown in the upper part of the figure.<br />

FUDS lasts 1,372 seconds, has 17 stops, and reaches a maximum speed of 56.7 miles/hour. The two<br />

histograms show the distributions of speed and acceleration in the cycle.<br />

44

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