# Multi-Agent Simulation Environment for Logistics Warehouse Design Based on Self-Contained Agents
## 5 Experiment to Compare Development Costs
### Comparison of Development Costs  
Compared to using the existing simulation modeling environment (NetLogo), our simulation environment can reduce the development cost by 31.5 %. Figure 11 shows the experimental  
Figure 10: Overview of target distribution warehouse for modeling experiment (a snapshot of simulation result visualization interface). results regarding the development costs using the proposed simulation environment and NetLogo. These development costs are calculated by counting the number of lines of codes except the comments and blank lines. We evaluated the modifiability of the developed simulation models. We used the architectural modifiability analysis (ALMA) [10] concept to examine the modifiability of developed multi-agent model. We designed the evaluation in reference to the existing work [25] that applied the ALMA concept to evaluate the modifiability of multi-agent systems. The ALMA allows the developers to elicit multiple cases of modification on the developed software and evaluate the ease of the modification in each case. In the process of designing logistics warehouses, most cases involve reconfiguration and/or replacement of material-handling equipment to assess the productivity. We elicited the practical cases by interviewing a company's employees designing and operating logistics warehouses. Table 2 shows an essential part of the result of modification cost evaluation. LoC (Line of Codes) is the affected part of the source codes in the modified programs. The rest of the result is explained in the Appendix A. Case 1 (C1) is a modification case of replacing the iCarry transport system with another transport system. In the case of NetLogo, developers first need to review the procedures and global variables, then delete the procedures for iCarry transport system, modify the map information and finally develop the codes for new transport system. In the case of our environment, developers first delete the iCarry agents, then modify the map information in spatial-temporal agent, and finally develop and add the agents of the new transport system using the agent core library. Developing simulation model of the new transport system is necessary in both NetLogo and our environment, but since the previous experimental result shows that the model development costs is relatively low in our environment, overall, using our environment is easier cope with case 1. Case 2 (C2) is a modification case of replacing the Racrew picking system with another picking system. In the case of NetLogo, developers first need to review the procedures and global variables, then delete the procedures for Racrew picking system, modify the WMS simulation part, modify the map information using a designated editor, and finally develop and add the procedures for the new picking system. In the case of our environment, developers first need to delete the Racrew agents, review and modify the WMS agent and spatial-temporal agent, and finally develop and add the agents of the new picking system using the agent core library. Developing simulation model of the new transport system is necessary in both NetLogo and our environment, but since the previous experimental result shows that the model development costs is relatively low in our environment, overall, using our environment is easier cope with case 2. Figure 11: Cost of modeling distribution warehouse with NetLogo and prototyped simulation environments. \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} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Case** & **Modification** & \multicolumn{4}{c}{**Conventional Simulation Environment**} & \multicolumn{4}{c}{**Proposed Simulation Environment**} \\ \cline{3-14}
**ID** & **Case Description** & **Required Modification Procedures** & **Reviewed and Modified Parts** & **LoC** & **Required Modification Procedures** & **Reviewed and Modified Parts** & **LoC** \\ \hline \hline \multirow{9}{*}{C1} & & 1.