## 4 Experiment
### Experiments Outdoors
#### 4.3.2 Test Data Processing  
The amount of droplet deposition is a significant parameter reflecting the quality of droplet deposition per unit area [27]. The Mylar card that is a resin card collected by the test is eluted with 20 mL of distilled water, and six Rhodamine B solutions with different concentrations were set for calibration in the range of absorbance of the fluorescence spectrophotometer (F-380, Tianjin Gangdong Technology Development Co., Ltd., China). Concentrations of Rhodamine B solutions were 0.002 ug/mL, 0.005 ug/mL, 0.01 ug/mL, 0.02 ug/mL, 0.05 ug/mL, and 0.1 ug/mL. The specific method was as follows: three parts of each standard solution were prepared, and each repeated  
Figure 16: Inner sampling bands of adjacent operation units. **Note:** S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, and S13 are the numbers of the collection bands.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sorties** & **Temperature (\({}^{\circ}\)C)** & **Humidity (\%)** & **Wind Speed and Direction** \\  & & & **(m-s\({}^{-1}\))** \\ \hline
1 & 19.5 & 54.3 & 0.54/SW \\
2 & 20.1 & 54.2 & 0.78/SW \\
3 & 21.3 & 53.9 & 0.84/SW \\
4 & 22.6 & 53.7 & 0.47/SW \\ \hline \hline \end{tabular}
\end{table}
Table 3: Test environment parameter list.  
Figure 17: Layout of the Mylar card and water-sensitive paper.  
measurement was performed twice to monitor the influence of the cuvette on the measurement result. Therefore, the actual number of repeated measurements for each standard solution amount to six times, and the Rhodamine B solution concentration absorbance curve is shown in Figure 18.  
By linear regression fitting, the coefficient of determination R\({}^{2}\) is 0.9997. The standard curve gives the concentration of the sample solution, thereby calculating the deposition amount per unit area [28]. The calculation equation is as follows:  
\[\beta_{dep}=\frac{(\rho_{sampl}-\rho_{blk})F_{cal}V_{dil}}{\rho_{spray}A_{col}} \tag{6}\]  
where \(\beta_{dep}\) is the amount of droplet deposition in g\(\cdot\)cm\({}^{-2}\); \(\rho_{sampl}\) is the reading of the sample solution fluorescence meter; \(\rho_{blk}\) is the reading of the fluorescence meter of the eluent (distilled water for this test); \(F_{cal}\) is the calibration coefficient in g\(\cdot\)L\({}^{-1}\); \(V_{dil}\) is the volume of the solution used to elute the collected sample in L; \(\rho_{spray}\) is the concentration of the fluorescent tracer in the spray solution in %; \(A_{col}\) is the area of the collected card in cm\({}^{2}\).  
The water-sensitive paper collected by the test was scanned and analyzed by DepositScan software (USDA-ARS Application Technology Research Unit, Wooster, OH, USA), and the droplet deposition rate and deposition density under different prescription values were obtained [29]. The coefficient of variation is usually used to represent the uniformity of droplet deposition between different collection points for the same collection [30]. The calculation equation is:  
\[CV=\frac{S}{\overline{X}}\times 100\% \tag{7}\]  
\[S=\sqrt{\sum_{i=1}^{n}{(X_{i}-\overline{X})}^{2}/(n-1)} \tag{8}\]  
where \(S\) is the standard deviation of the sampled specimens in the same collection zone; \(X_{i}\) is the deposition amount of each collection point in \(\mu\)L\(\cdot\)cm\({}^{-2}\); \(\overline{X}\) is the average value of the deposition amount of the sampling points of the same collection zone in \(\mu\)L\(\cdot\)cm\({}^{-2}\); and \(n\) is the group sampling with the number of collection points.  
Figure 18: Rhodamine B solution standard concentration absorbance curve.