## 6 Experimental Results
### Virtuino App for Logging and Visualizing Sensor Values  
In the above section, we have calculated, calibrated, and validated the sensor values with a real instrument. Now, we will discuss the sensor values logging into a cloud-based app. Figure 16 presents the real experimental setup with the cloud application. Figure 16 clearly illustrates the deployment of the lower tank monitoring unit and upper tank monitoring unit. Upper tank monitoring and lower tank monitoring unit based on 2.4 GHz RF communication. Moreover, the upper tank monitoring unit is integrating with ESP 8266 Wi-Fi module. This enables the transmission of the sensory values of pH, flow, and ultrasonic sensors on the Virtuino cloud application through internet connectivity. Additionally, the Virtuino application assists the user to monitor and visualize the status of the upper tank through the internet. The Virtuino application provides a graphical user interface-based dashboard to control and visualize the data of the physical things and sensors. The Virtuino application is based on the Virtuino server. Virtuino is useful for controlling the hardware boards that are integrated with Virtuino through Bluetooth and Wi-Fi. Figure 17 illustrates the sensory value of the upper tank monitoring unit on the Virtuino app. As discussed earlier, the three different sensors are utilized in the upper tank for monitoring the level of water, pH value of water, and flow rate of water. The sensory values of the ultrasonic sensor are represented in centimeters (cm), the flow rate of water is represented as liters per minute (L/MIN) and the pH value does not have any units to represent. Generally, if the pH value is below 7, then it is considered as an acidic substance and if the pH value is above 7 then it is considered as a basic substance. Here, the Virtuino application is visualizing the three sensor values at three different time intervals. In Figure 17a the level of the water in the upper tank is visualized as 15 cm with a flow rate of 2 L/MIN and the pH value of the water is visualized as 7. In Figure 17b the level of the water in the upper tank has remained the same i.e.,15 cm with the same flow rate of 2 L/MIN, and however the pH value of the water is increased to 8. Here the water pump is switched and the amount of water in the upper tank is increased to 20 cm with the same flow rate of 2 L/MIN and however, the pH value of the water remains constant, i.e., 8. Finally, the results conclude that the proposed architecture for upper water monitoring is performing effectively, as the upper tank monitoring unit can log the sensory value of the level sensor, pH sensor, and flow rate sensor on the cloud-enabled Virtuino app. Table 4 summarizes the sensor value obtained on the Virtuino dashboard, where the pH sensor, water level, and flow rate of three Virtuino dashboards are presented (see Tables 4 and 5). \begin{table}
\begin{tabular}{c c} \hline \hline
**Case ‘1’** & **Case ‘2’** \\ \hline pH Sensor value obtained for pH 9.20 buffer solution = 8.90 & pH Sensor value obtained for pH 9.20 buffer solution = 8.50 \\ Error value = 9.20 \(-\) 8.90 = 0.30 & Error value = 9.20 \(-\) 8.50 = 0.70 \\ pH value obtained for water = 8.07 & pH value obtained for water = 7.33 \\ Actual pH value = 8.07 + 0.30 = 8.37 & Actual pH value = 7.33 + 0.70 = 8.03 \\ Actual pH value = 8.37 & Actual pH value = 8.03 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Calibration of the pH sensor at pH 9.20 buffer solution. Figure 16: pH obtained for sample water solution. Figure 17: Virtuino dashboard displaying sensor values. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Dashboard** & **pH Sensor** & **Water Level (cm)** & **Flow Rate (L/min)** \\ \hline Dashboard \({}^{\prime}1^{\prime}\) & 7 & 15 & 2 \\ \hline Dashboard \({}^{\prime}2^{\prime}\) & 8 & 15 & 2 \\ \hline Dashboard \({}^{\prime}3^{\prime}\) & 8 & 20 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Sensor value of pH, water level and flow rate of the water tank.