## 2 Materials and Methods
### Garbage Collection Operations  
This paragraph describes the vehicle operations and single tasks assumed to be required for the garbage collection and the traveling phase in a typical workday. The compactor truck travels to waste collection points (traveling activity) powered by the thermal engine. When the truck stops to collect garbage (idling activity), the hydraulic pump that provides the handling mechanism is directly engaged to the combustion engine shaft in the case of the ICE-HPS, or the electric motor shaft in the case of the proposed e-HPS. The proposed e-HPS, described in Section 2.1, allows the accomplishment of all garbage collection operations. To model the collection system, three different phases were taken into account, namely: (1) the dumpster lift; (2) the garbage compaction; and (3) the load discharge. In the first phase, the dumpster lift cycle consists of lifting large garbage dumpsters and discharging the garbage contained within the dumpster into the enclosed vehicle hopper. During this operation, the rear-mounted lifting comb device engages the longitudinal sidewall of the garbage dumpster and lifts it until it reaches the discharge position, then, through the movement of a specific hydraulic device, the garbage is tipped into the truck hopper. In the second phase, the garbage compaction is operated by means of a metal pusher plate within the truck body, which, through an oscillating movement, pushes the garbage against the mass already loaded and retracts. It should be noted that for each garbage load in the truck body, two garbage pushes are required to complete the compaction operation. The system for compaction is composed of an articulated single-bladed plate, activated by four double-action hydraulic cylinders. In the final, third phase, when the truck body is full, it is necessary to discharge the garbage load onto a dump site. This operation involves the stabilization of the truck through a specific mechanical device (stabilizer), the lifting of the truck body, and the final push of the garbage from the vehicle body. Garbage collection operations and tasks provided by the compactor truck, and the related mechanical power and task times, are summarized in Table 1. The values of pump speed, mechanical power, temporal duration, and number of cycles for each phase, reported in Table 1, are defined by the company Fratelli Mazzocchia SPA. \begin{table}
\begin{tabular}{p{42.7 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Phase** & **Operation** & **Task** & \
\begin{tabular}{c} **Pump Speed** \\ **(rpm)** \\ \end{tabular} & **Power (kW)** & **Task Time (s)** &
\begin{tabular}{c} **Number of Cycles** \\ **Per Workday** \\ \end{tabular} \\ \hline
1 & \begin{tabular}{c} Dumpster lift \\ \end{tabular} & \begin{tabular}{c} Dumpster lifting \\ \end{tabular} & \begin{tabular}{c} 1110 \\ 1110 \\ \end{tabular} & \begin{tabular}{c} 3.4 \\ 6.4 \\ \end{tabular} & \
\begin{tabular}{c} 8.6 \\ 4.9 \\ \end{tabular} &
\begin{tabular}{c} 100 \\ 100 \\ \end{tabular} \\ \hline
2 & \begin{tabular}{c} Garbage compaction \\ \end{tabular} & \begin{tabular}{c} Garbage pushing \\ \end{tabular} & \begin{tabular}{c} 3000 \\ 1000 \\ \end{tabular} & \begin{tabular}{c} 8.2 \\ 750 \\ \end{tabular} & \begin{tabular}{c} 14.7 \\ 5.9 \\ \end{tabular} & \
\begin{tabular}{c} 200 \\ 5.5 \\ \end{tabular} &
\begin{tabular}{c} 200 \\ 5.5 \\ \end{tabular} \\ \hline
3 & \begin{tabular}{c} Load discharge \\ \end{tabular} & \begin{tabular}{c} 2000 \\ 2000 \\ \end{tabular} & \begin{tabular}{c} Truck stabilization \\ \end{tabular} & \begin{tabular}{c} 1000 \\ 1000 \\ \end{tabular} & \begin{tabular}{c} 3.1 \\ 6.3 \\ 47.9 \\ \end{tabular} & \
\begin{tabular}{c} 9.8 \\ 3 \\ 47.9 \\ \end{tabular} &
\begin{tabular}{c} 3 \\ 47.9 \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Garbage collection operations and tasks executed by the compactor truck with related mechanical power and task times.