## 2 Methodological and Operational Framework for CDTs
### Enablers for CDTs in Agile Supply Chains
#### 2.3.3 Lifecycle  
This refers to the ability to monitor and control the DT behaviour through its entire lifecycle. As the DT illustrates the behaviour of a physical entity, the DT lifecycle can be considered from the Product Lifecycle view [20; 29], consisting of the following steps:  
* Creation, where the profile of a DT is defined. Different configurations are assessed and--using data streams--\"asset\"s\" behaviour model is identified. This is achieved  
Figure 1: Basic CDT enablers. through experimentations/simulations and removing unpredicted and undesirable behaviours. * Production, where interfaces and created between the DT and physical asset and are ready to communicate each other. * Operation, where information between physical asset and DT is exchanged. There any change in the physical asset (e.g., parts replacement) updates the DT model and further information coming from the DT can predict anomalies or changes in the physical asset's behaviour. In principle, the operation is a continuous alignment of the physical and virtual operation. * Disposal or recycling. At the final stage, the full operation of a DT is considered as source of learning to avoid future mistakes in next modelled production systems. During the CDT lifecycle, the cognition models play a very important role since they model, calibrate and improve the CDT's behaviour. From the early phases of the CDT design (Create and Production) we need to experiment different scenarios and conclude on a particular desired behavioural model to be made. The desired behaviour also needs to be calibrated with first operational data, which validates and refines the initial assumptions. In the operational level we are dealing with information about the actual operation and possible deviations that reflect either failures or even areas of improvement. Finally, at the disposal level, we have a complete set of knowledge about the CDT's operation (associations, rules, behavioural aspects), which can be replicated in the design and operation of other CDTs thus minimizing the design time and cost. Recyclability of the CDTs in this case is about reusing the knowledge/lessons learnt about the CDT in a particular context and applying it in a similar case. Depending on the application, different DT lifecycles from the creation, duration and end of life perspective may appear. At first, we have the static CDTs, for example, in a production line inside a factory, a machine that has a long lifetime and is part of a fixed process (which behaviour can of course be upgraded but as an entity remains a long). In such a case, the production line is a network of such fixed CDTs. We might also have the case of an ad-hoc and more dynamic CDT. This is a case where in existing production of supply chain networks we have for specific occasions the need to incorporate a physical asset in an operation. Let us take the example of collaborative logistics where a truck has a problem on the route and must find an alternative solution. if we consider the logistics operation as a distributed network of collaborative CDTs (Logistics Objects), the truck can identify a collaborator (i.e., another truck, which is in a close geographical range) that goes to the same direction, fulfils all the needs of delivery (conditions, capacity) and the governance/collaboration rules. In such case, the CDTs of those trucks can identify through \"social networks\" such CDTs and \"tweet\" each other to negotiate a collaboration [30]. Another example is the case of customized products. For a particular feature requested by a customer, the manufacturer might need to assess different external asset providers (e.g., 3D printing), which can deliver the part to be integrated in the product. In such case, a DT of the candidate producer can be built in line with the CDT enablers so to assess the performance. The lifetime of this CDT can be:  
* Very short (creating and operating only in the planning phase: just examining whether to collaborate with a producer).