## 2 Materials and Methods
### Experimental Methodology and Data Collection  
A field study was conducted to evaluate the performance of two identical combines, but with different guide vane assemblies; the most important parameters are shown in Table 2. Combine A was equipped with the modified rotor top cover guide vane assembly--eight guide vanes linked together. Combine B maintained the standard top cover with two fixed front vanes and six adjustable rear vanes. Both combines were equipped with factory-installed Original Equipment Manufacturer (OEM) telemetry modems that have integrated Global Positioning System (GPS) tracking, as well as real-time monitoring of machine parameters via the Controller Area Network (CAN-bus) protocol. This setup enabled the collection of data such as fuel consumption, engine load, grain yield flow, throughput, broken grain, separation losses, and sieve losses (Table 3). These data were linked to geographic coordinates, allowing for location-specific performance analysis throughout the field area. Figure 7: The modified top cover installation into the combine. Crop biometrical indices were determined for winter wheat Ada plants; the crops were harvested and weighed from five plots of 0.25 m\({}^{2}\) of the field (reading accuracy 0.01 g). The length of the stem average was determined. The threshed grains from the ears were weighed, and their moisture content was determined to be 14%. Determination of feed flow rate \(Q\) (total biological mass entering the threshing system) was calculated using crop mass per square meter, header width, and travel speed. The average total biological mass was based on field sampling. Feed flow rate \(Q\) was calculated using the formula:  
\[Q=m_{b}\cdot W\cdot v \tag{5}\]  
where \(Q\) is feed flow rate (kg s\({}^{-1}\)), \(m_{b}\) is biological mass per square meter (kg m\({}^{-2}\)), \(W\) working header width (m), and \(v\) is the forward speed of the combine (m s\({}^{-1}\)). The forward speed \(v\) was not held constant, allowing the travel speed to vary based on guide vane angle and crop resistance. Actual forward speeds were recorded using GPS and CAN telemetry and used in the formula. To evaluate the fuel efficiency of the combine under different guide vane configurations, fuel consumption was analyzed not only in absolute terms (liters per hour) but also as a function of productivity. The fuel consumption per ton of harvested grain was calculated using the following formula:  
\[C_{f}=\frac{F}{P} \tag{6}\]  
where \(C_{f}\) is fuel consumption (L t\({}^{-1}\)), \(F\)--fuel consumption rate (L h\({}^{-1}\)) monitored by telemetry, and \(P\)--throughput (t h\({}^{-1}\)) determined from yield monitor data. Grain losses were determined, and loss sensors were readjusted prior to the experiment. To determine grain losses, the \"BushelPlus SmartPan (Bushel Plus Ltd., Brandon, MB, Canada)\" system was used. This is a drop pan system that is magnetically mounted beneath the combine (Figure 8). The pan is automatically released from the mobile application \"SmartDrop (Bushel Plus Ltd., Brandon, MB, Canada)\" and drops to the ground, collecting \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Indices**} & \multicolumn{2}{c}{**Combine-Harvester**} \\ \cline{2-3}  & **A** & **B** \\ \hline Engine power & 480 HP & 480 HP \\ Rotor diameter & 0.762 m & 0.762 m \\ Rotor length & 2.638 m & 2.638 m \\ Rotor speed & 980 rpm & 980 rpm \\ Concave clearance & 0.015 m & 0.015 m \\ Top cover guide vanes & 8 linked, adjustable & 2 fixed + 6 adjustable \\ Header width & 12 m & 12 m \\ Telemetry modem & Integrated with GPS receiver & Integrated with GPS receiver \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The most important technical data of combine-harvesters.