Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p14
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 14/71)
Character Range: 245599–250508

the cycle work

              The actual cycle work Wact (kWh) shall be calculated using each pair of engine feedback speed and torque values recorded. This shall be done after any feedback data shift has occurred, if this option is selected. The actual cycle work Wact is used for comparison to the reference cycle work Wref and for calculating the brake specific emissions (see Sections 4.4 and 5.2). The same methodology shall be used for integrating both reference and actual engine power. If values are to be determined between adjacent reference or adjacent measured values, linear interpolation shall be used.

              In integrating the reference and actual cycle work, all negative torque values shall be set equal to zero and included. If integration is performed at a frequency of less than 5 Hertz, and if, during a given time segment, the torque value changes from positive to negative or negative to positive, the negative portion shall be computed and set equal to zero. The positive portion shall be included in the integrated value.
              Wact shall be between − 15 % and + 5 % of Wref

3.9.3.                        Validation statistics of the test cycle

              Linear regressions of the feedback values on the reference values shall be performed for speed, torque and power. This shall be done after any feedback data shift has occurred, if this option is selected. The method   of least squares shall be used, with the best fit equation having the form:

        y = mx + b

              where:

              y  =  feedback (actual) value of speed (min−1), torque (Nm), or power (kW)  m = slope of the regression line
              x  =   reference value of speed (min−1), torque (Nm), or power (kW)   b = y intercept of the regression line
              The standard error of estimate (SE) of y on x and the coefficient of determination (r2) shall be calculated for each regression line.

              It is recommended that this analysis be performed at 1 Hertz. All negative reference torque values and the associated feedback values shall be deleted from the calculation of cycle torque and power validation statistics. For a test to be considered valid, the criteria of Table 6 must be met.

        Table 6

        Regression line tolerances
                                                                                                                                                                                                                                                                                                 Speed               Torque                                                     Power
Standard error of estimate (SE) of Y on X                                                                                                                                                                                                                                                     Max 100 min–1     Max 13 % (15 %) (*) of power map maximum engine torque     Max 8 % (15 %) (*) of power map maximum engine power
Slope of the regression line, m                                                                                                                                                                                                                                                               0,95 to 1,03      0,83–1,03                                                  0,89–1,03
                                                                                                                                                                                                                                                                                                                                                                           (0,83–1,03) (*)
Coefficient of determination, r2                                                                                                                                                                                                                                                              min 0,9700        min 0,8800                                                 min 0,9100
                                                                                                                                                                                                                                                                                              (min 0,9500) (*)  (min 0,7500) (*)                                           (min 0,7500) (*)
Y intercept of the regression line, b                                                                                                                                                                                                                                                         ± 50 min-1        ± 20 Nm or ± 2