# OntoIMM: An Ontology for Product Intelligent Master Model
## 5 Case Study: Design and Analysis of Gun-Barrel
### Similar Case Acquiring  
The acquisition of similar cases needs to calculate the similarity of product characteristics, which mainly includes the tactical and technical requirements for a firearms product. The concept Requirement is defined in OntoIMM and instantiated when parsed for reuse in intelligent design platform. Requirement is specialized into five types, including textual, numerical, interval, fuzzy, and containing, corresponding to similarity algorithms, respectively. Textual indicator refers to the descriptive indicators in this paper, such as fight task requirement; Numerical indicator is the quantitative description of an indicator, such as fighting rate of fire and theoretical rate of fire; Fuzzy indicator is expressed as membership function, such as material yield strength. The containing indicator is used to restrict the compatibility of products to specific objects or functions, for instance, a used bullet may contain several kinds of bullets. The selected requirement indexes and their values are shown in Table 4.  
Figure 7: Detailed information for gun-barrel design analysis based on OntoIMM.  
The similarity algorithms code integrated are called to comprehensively calculate the similarity of requirement characteristics. The comprehensively similarity of a design case can be expressed as  
\[\text{Sim(X,Y)}=\omega_{\text{t}}\text{Sim}_{\text{t}}+\omega_{\text{n}}\text{Sim }_{\text{n}}+\omega_{\text{i}}\text{Sim}_{\text{i}}+\omega_{\text{f}}\text{Sim}_{ \text{f}}+\omega_{\text{c}}\text{Sim}_{\text{c}}, \tag{1}\]  
where \(\omega_{\text{t}}\), \(\omega_{\text{n}}\), \(\omega_{\text{i}}\), \(\omega_{\text{f}}\), and \(\omega_{\text{c}}\) are the weight of textual, numerical, interval, fuzzy and containing indexes, respectively, and their values range from 0 to 1. \(\text{Sim}_{\text{t}}\), \(\text{Sim}_{\text{n}}\), \(\text{Sim}_{\text{i}}\), \(\text{Sim}_{\text{f}}\),and \(\text{Sim}_{\text{c}}\) are the similarity of textual, numerical, interval, fuzzy, and containing indexes. Taking numerical indexes as an example, the calculation formula of similarity is represented by  
\[\text{SIM}_{\text{n}}(\text{X,Y})\ =1-\frac{|\text{X}_{\text{val}}-\text{Y}_{ \text{val}}|}{\text{MAX}_{\text{val}}-\text{MIN}_{\text{val}}}, \tag{2}\]  
where X and Y are the same numerical index; \(\text{MAX}_{\text{val}}\) and \(\text{MIN}_{\text{val}}\) are the upper and lower bounds of X and Y, respectively; and\(\text{X}_{\text{val}}\) and \(\text{Y}_{\text{val}}\) are the specific values of X and Y, respectively.  
Several similar cases will be obtained, and the specific value and similarity of each index of selected similar case will be shown on the system interface to help engineers view and select, as shown in Figure 8.  
\begin{table}
\begin{tabular}{l l l} \hline
**Selected Requirement** & **Type** & **Value** \\ \hline Caliber (mm) & numerical & 12.7 \\ Effective range (m) & numerical & 1500 \\ Whole weight limit(kg) & numerical & 25 \\ Whole length limit (mm) & numerical & 120 \\ Barrel length limit (mm) & numerical & 600 \\ Initial velocity limit (m/s) & numerical & 750 \\ Theoretical rate of fire (round /min) & numerical & 800 \\ Fighting rate of fire (round /min) & numerical & 300 \\ Used bullet & containing & Armor-piercing incendiary, type 54, 12.7 mm \\ Fight task & textual & Flexible operation, detachable transport, high \\  & reliability and low failure rate \\ Material & textual & Easy access, enough strength and low cost \\ Maintenance & textual & Standards conformance and good maintainability \\ \hline \end{tabular}
\end{table}
Table 4: The tactical and technical indexes.  
Figure 8: Similar case acquiring.  
As shown in Table 4, the comprehensive similarity of case is displayed on the user interface, and the index value will be displayed according to the selected case by model mapping. The input values of selected requirements will initial fulfill the barrel design information, which will be used and updated at later design stages.