# QB4 MobOLAP: A Vocabulary Extension for Mobility OLAP on the Semantic Web
## 3 Research Methods
### Use Case Scenario: Oil Palm Fresh Fruit Bunches Transportation  
This research utilizes the use case in the transportation of the oil palm fresh fruit bunches (FFB) in Indonesia's plantations. This use case is applied to evaluate or prove the concept of the QB4 MobOLAP Vocabulary and its query function. \begin{table}
\begin{tabular}{c c} \hline \hline
**Class** & **Operators** \\ \hline Projection to domain/range & Deffime, RangeValues, Trajectory \\ Predicates (Boolean) & IsDefinedAt, IsHasValue \\ Interaction with domain/range & AtTimeStamp, AtPeriod, InitialInstant, InitialValue, FinallInstant, FinalValue, At, \\  & AtMin, AtMax, startSequence, endSequence, etc \\ Rate of Change & Derivative, Speed, Turn \\ Mobility Row Aggregation & Integral, TWAvg, TWVariance, TWStDev, TWMax, TWMin \\ Mobility Spatial Aggregation & TCentroid, TUnion, TConvexHull, TIntersect, TMB \\ Lifting Function Aggregation & TCount, TMax, TMin, TAvg, TSum \\ Spatial Operation & InsideGeometry, InsideRadius, Length, CumulativeLength \\ Temporal Operation & Duration \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The function and aggregation operators of mobility types (adapted from [50]). Figure 3: Example of the lifted function of trajectory mobility types (**a**) trajectory in x and y-axis, (**b**) trajectory in x,y, and time axis, (**c**) Grid-based Spatial Sum of Truckload, (**d**) TSum and TAvg lifting functions. The palm plantation wants to minimize transportation time, cost, and loading/unloading time to increase the quality of the fresh fruit by means of Mobility OLAP in order to find descriptive, diagnostic, and discovery information. Figure 4 depicts the FFB transportation process from harvesting until Palm Oil Mill (POM). Fruit harvesting is the first step of the crucial phase in the FFB transportation process. The fruit is then collected into the Fruit Collection Point (FCP) using such technology as the net system or the grabber system, or is collected manually. After being collected, the Fresh Fruit Bunch (FFB) will be transported to the POM according to the following steps: loading to the truck, thrilling to the POM, entering and queueing in the factory gate, weighing, and unloading into the loading ramp, and finally, the FFB will be processed in the POM. This cycle takes time and significantly affects the quality of the palm oil, especially when the fruit has bruised. Figure 5 shows an example of the MultiDim logical model of Mobility DW for Oil Palm FFB Transportation analysis. The design has a Delivery Fact Table that has mobility measures and dimensions. The Fact Delivery has five measures. Route t(\(\bullet\)) is a measure of the trajectory of truck positions at any point in time. The Load t() is an integer type measure that changes over time. The trajectory is a spatial type of measure represented by a line with a symbol. The other measures are Distance, as a numeric type, and Duration, as a time type. The Route t(\(\bullet\)) measure, as a temporal point type, allows deliveries to be aggregated along the dimensions. For example, a similar route could be merged into a single route; the route could be a union and an intersection, etc. Thus, a query such as _\"give me the total distance of trajectory by TruckOwner\"_ or _\"give me the total truckload that passes road segment \(X\) in February\"_ could be answered. A query such as _\"give the average of fruit loading time by month and plantation block\"_, where fruit loading time has been computed using a spatial operator within a radius, could be computed. These queries are examples of a spatial roll-up function. The delivery fact has a relationship with five dimensions, Truck, Date, and Plantation, where the latter is a spatial dimension related to the fact through many-to-many relationships. The truck dimension is composed of two levels with a one-to-many relationship.