## 3 Architecture of DT Workshop System
### Design of DT Workshop Architecture Based on Five-Dimensional Model  
Based on the five-dimensional model concept proposed in the literature [5], this paper designs the ocean engineering manufacturing DT workshop architecture as shown in Figure 3. The architecture unfolds from the 5D model, including Physical Entities (PE), Virtual Objects (VO), DT Data (DD), Connections (CN), and Application Services (AS), whose vector format can be expressed as Equation (1). \[\mathbf{M}_{DT\_workshop}=(\mathbf{PE},\mathbf{VO},\mathbf{DD},\mathbf{CN},\mathbf{AS})^{\rm T} \tag{1}\]  
Figure 2: Integrated manufacturing execution mode for “Humans–Machines–Materials–Rules–Environments”. In the implementation of the digital twin workshop, five dimensions correspond to the Equipment Layer, the Data Acquisition Layer, the Service Drive Layer, the Application Service Layer, and the Digital Twin Display Layer, with each layer corresponding to handling various complex tasks. The architecture from the bottom up specifically includes:  
* Equipment Layer  
This is the collection of physical entities. By establishing data tables for all production elements in the workshop, distinguishing fully automated uncrewed equipment from manually operated equipment by categories such as equipment, supplies, and buffers, forming information labels for corresponding entities, establishing fields for equipment status, operators, supplier information, consumables spare capacity, etc. These allow real-time mapping with subsequent operational processes to complete DT data input to equipment operation as well as actual measurement data feedback to DT console. The vectorized representation of \(\mathbf{PE}\) is shown in Equations (2)-(5). \[\mathbf{PE}=(\mathbf{E},\mathbf{M},\mathbf{A},\cdots)^{\mathrm{T}} \tag{2}\]  
\[\mathbf{E}=(\mathbf{No},\mathbf{EquipmentName},\mathbf{Status},\mathbf{Operator},\mathbf{Supplier},\mathbf{ Amount},\cdots)^{\mathrm{T}} \tag{3}\]  
Figure 3: Ocean engineering manufacturing DT workshop architecture. \[\mathbf{M}=(No.,MaterialName,Amount,Supplier,\cdots)^{\mathrm{T}} \tag{4}\]  
\[\mathbf{A}=(No.,AreaName,Location,Size,\cdots)^{\mathrm{T}} \tag{5}\]  
where \(\mathbf{E}\) represents the equipment, \(\mathbf{M}\) is the material, and \(\mathbf{A}\) is the area, each containing their respective detailed properties. * Data Acquisition Layer  
This layer collects or uploads shop operation execution data through sensors, surveillance cameras, QR codes/RFID, etc., and develops heterogeneous data interfaces to link the equipment layer with the service driver layer. The scope of data collection includes, but is not limited to, equipment operation data, transportation process awareness, material information tracking, equipment status feedback, environmental monitoring, etc. The data interface development workload is enormous and requires one-to-one customization to be completed based on multiple models, protocols, and standards of the equipment to form a data chain for real-time transmission. An enormous quantity of basic work is a necessary component of constructing the DT workshop. The integrity and standardization of the collected data determine the operational efficiency and calculation accuracy of the service driver layer. The vectorized representation of the data connection process is exemplified by Equation (6). As the central layer of the digital twin system, the service drive layer is responsible for data reception, conversion, and application. The data is accessed by the equipment layer feedback and digital twin emulation via interfaces to the Enterprise Services Bus and Data Warehouse. The data integration component standardizes the multi-source heterogeneous content in the database and updates the master database based on the information provided by the real-time mapping. The standardized production data is available to be input into the GNN-based DT workshop model to obtain the manufacturing execution plan with workshop schedule and optimal allocation of multiple resources.