# Developing a Digital Twin and Digital Thread Framework for an 'Industry 4.0' Shipyard
## 1 Introduction  
Digital twin (DTW) technology is the cornerstone of digital transformation, which we are currently witnessing in the new industry 4.0 revolution. DTW is accessible now more than ever and many reputable and innovative companies such as Tesla and Siemens have adopted it with varying success. Siemens [1] has integrated DTW into its three major sections of product lifecycle: product, production and performance. The virtual representation of the product is created and tested to validate performance under expected use conditions. Production is optimized through manufacturing process simulations where any sources of error or failure can be identified and prevented before proceeding to physical production. Subsequently, DTW has potential to improve performance by producing high-quality products at lowest logical cost by integrating manufacturing processes and enhancing production planning in manufacturing implementation [2]. In addition to companies in the business of manufacturing products, companies in other sectors such as the National Aeronautics and Space Administration (NASA), a pioneer of the DTW, used this technology to develop ultra-high fidelity simulation models of aerospace vehicles. These simulations enabled NASA's engineering team to predict the future performance and status of their vehicles accurately in the form of the \"factors-of-safety\" during design and certification phases. It also enabled mission managers to make informed decisions based on historical and real-time data to improvise possible in-flight changes to a vehicle's mission [3]. The global medical industry has been utilizing DTW to test medical devices virtually before introducing them into the physical world. For example, the Living Heart Project has adapted DTW for cardiovascular surgeons in diagnosis, education and training [4]. This project is not limited to cardiovascular surgeons but has positive implications for medical device design, clinical diagnosis and regulatory science. The fundamentals of this project involve the use of both pacemakers in live participants and virtual patients with the goal of increasing industry innovation in tackling heart diseases. Further practical use of DTW in the medical industry relates to tailoring health care to individuals. In South Korea, DTW is being utilized in combination with Medical Artificial Intelligence to tailor healthcare plans to individual patients [5]. This, in conjunction with information on tracked health and lifestyle data from wearable devices, could eventually result in a \"virtual patient.\" Virtual patient models allow medical personnel to perform continuous remote monitoring on patients at low-cost and provide health predictions and prescribe preventive treatments promptly. Through such interventions, South Koreans have benefitted from significant health improvements, reductions in healthcare costs and increased personal freedom in dealing with their own health. Beyond healthcare, DTW is employed on a large scale in urban planning. For example, Virtual Singapore is a dynamic 3D city model [6] that consists of a detailed 3D map of Singapore and contains information such as texture and material representations of geometrical objects, terrain attributes and infrastructure and so forth. This 3D model is useful in virtual experimentation, virtual test-bedding, planning and decision-making and research and development. Despite DTW being accessible now to most companies and governments, the adoption and uptake in Australian small- and medium-sized enterprise (SME) is still very slow. For most SMEs, tackling industry 4.0 problems requires a number of enabling technologies such as Product Lifecycle Management (PLM) software, enterprise resource planning (ERP) packages, the Internet of Things (IoT) and Cyber-Physical Systems (CPS), which communicate and cooperate with each other in real time. Unfortunately, it can be difficult for SMEs to integrate data into these systems when they have been developed by separate firms.