## 4 Case Study--Analysis of Disruptions
### Results Analysis, Conclusions, and Recommendations
These three components of delivery time--waiting time for a loaded container at the gate, transport time, and unloading time--make up the actual delivery time shown in the figure above. Another important aspect regarding process quality was the analysis of the hours during which container shipments are carried out. This is significant because the isothermal containers are transported in standard vehicles, not isother  
Figure 6: The duration of logistic cycles. temperature has a significant impact. The hours of container shipments are presented in Figure 7.  
As shown in the above figure, shipments are carried out almost continuously for fresh deliveries, while frozen deliveries are mainly sent from 5 p.m. to 11 p.m. It is worth noting that the company avoids shipments during the hours from 9 a.m. to 3 p.m. when the outside temperature is highest, and delivery times could be extended due to traffic congestion in the city. This is a very effective company policy. Analyzing the collected data, the circulation of containers was also examined, i.e., lost or delayed containers. Normally, containers should return to the distribution center (DC) with the next delivery, typically within 24-30 h. Thanks to the installation of gateways in the reception area of the DC, which allowed for the detection of returning containers, it was possible to determine which containers had been unaccounted for longer than two days. The analysis of lost and delayed containers is presented in Figure 8.  
It turns out that out of the 40 containers examined, a staggering 8 containers were outside the distribution center (DC) for more than 2 days. Some containers did not return to the DC for a month or two. This means that stores often hold containers for extended periods or lose them. This is a significant problem for container owners, as unused containers in the transportation system significantly increase operational costs. Proper management of container uses is recommended to reduce these costs and eliminate waste. Proper management means that containers should be assigned to the transport's tasks based on the technical state, readiness (clean and cooled to the required temperature for products), and frequency of use. Figure 7: Start times of cycles. The monitored containers were subjected to an analysis to determine how often they are used, i.e., whether their usage is consistent. The chart showing the most frequently used containers, with the container with the highest number of logistics cycles as the reference container, is presented in Figure 9.  
Figure 8: Identification of lost containers. Figure 9: Frequency of container use—compared by the most often used. During the analysis of container utilization, it was noticed that:  
* 26 containers are used correctly (above 70% utilization);
* 6 containers have low rotation rates, with utilization between 30% and 70%, and among them, 2 containers are considered lost;
* 8 containers are considered lost or have malfunctioning sensors (no data collected for over 10 days). The next step was to analyze the frequency of container utilization in an aggregated view. To achieve this, logistics cycles were distributed across weeks (Figure 10). The results are presented in the figure below. Due to incomplete weeks, data for weeks 20 and 28 were omitted from the analysis. The median number of cycles for the remaining weeks was 104, averaging 3.2 cycles per container per week (excluding the 8 lost containers). This confirms previous results that containers are often held for over 24 h, most commonly more than 2 days. As a result, container use is nearly twice as low as its maximum potential. Improving the use of containers is possible through better management of logistic processes. To achieve this, it is necessary to shorten the lengthening processes within the warehouse, such as waiting for loading, extended container cooling times, and long product picking times.