Our society is increasingly reliant upon engineered systems of unprecedented and growing complexity. As our manufacturing and service industries, and the products that they deliver, continue to complexify and interact, and we continue to extend and integrate our physical and digital infrastructure, we are becoming increasingly vulnerable to the cascading and escalating effects of failure in highly complex and evolving systems of systems. Consequently, it is becoming increasingly critical that we are able to understand and manage the risk and uncertainty in Complex Engineering Systems (CES) to provide reliant and optimal design and control solutions.

Research on natural complex systems is helping us to understand the implications of inter-dependencies within and between complex adaptive systems. However, unlike natural ecosystems, which may become more robust through diversifying, man-made complex systems tend to become more fragile as their complexity increases. If we are to deal with the challenge presented by complex engineered systems, we will need to exploit and synthesise our current understanding of natural and engineered systems, our current theories of complexity more generally.

The ENgineering COmplexity REsilience Network Plus (hereafter called ENCORE) addresses the Grand Challenge area of Risk and Resilience in CES. Our vision is to identify, develop and disseminate new methods to improve the resilience and sustainable long-term performance of complex engineered systems, initially including Cities and National Infrastructure, ICT and Energy Infrastructure, Complex Products: Aerospace (both Jet Engines and Space Launch and Recovery Systems) and later to explore the inclusion of Nuclear Submarines, Power Stations and Battlefield Systems. We have chosen these particular CES domains as they strike a balance between the challenges and opportunities that the UK faces for which complexity science can have a significant impact for our citizens and businesses whilst spanning sufficiently diverse fields to present cross-domain learning opportunities.

Our approach is to create shared learning from [1] the manner in which naturally complex systems cope with risk and uncertainty to deliver resilience (ecosystems, climate, finance, physiology, etc.) and how such strategies can be adapted for engineering systems; [2] how the tools and concepts of complexity science can contribute towards developing a greater understanding of risk, uncertainty and resilience, and [3] distilling world-class activity within individual CES domains to provide new insights for the design and management of other engineering systems.

Examples of the potential for the application of this field and which will be considered for inclusion in the feasibility studies include:
- Predicting equipment failures and their consequences in critical infrastructure systems;
- Developing a management heuristic that plays the same role as a "risk register", but addresses systemic resilience;
- Optimising the deployment of instrumentation required to manage cities and other CES effectively;
- Increasing the resilience of interdependent digital systems;
- Advancing models of cascading failure on networks such that they take account of node heterogeneity and in particular the different failure/recovery modes of different types of node.
- Improving the number of contexts in which CES can be deployed with replicable performance;
- Decreasing the likelihood of human behavioural errors in operating CES.
- Identifying the critical elements that constrain/define system performance most strongly;
- Extending system lifetimes and functionality;
- Mapping the relationship between complex system complexity and fragility;
- Characterising uncertainty and defining the inference process to transition from one phase to the other in the control of CES and in complex decision making processes.

Potential Impact:
The social, environmental and economic importance of reducing risk and the impacts of uncertainty in the design and management of complex engineering systems (CES) would be difficult to overestimate. This Grand Challenge Network will take a comprehensive and coordinated approach to CES research. It will do so in a way which is both general, by working on novel ideas which are applicable across a broad range of applications of whatever scale, and specific by looking at key themes within the identified Domains and Clusters. The beneficiaries from this work will therefore be:

Society because of:

- The impact on carbon emissions, sustainability and the environment
- The lowered disruption to economic infrastructure required to achieve that environmental improvement
- The opportunities for improved security of critical infrastructure such as transport, comms and energy

The UK Economy:

Through cross domain learning and the investigation of new techniques we aim to identify the means to exploit improvements in our understanding of risk and uncertainty in CES to improve their performance for two specific areas of national importance [1] the development of CES to create business opportunities for UK companies in a wide range of fields including Jet Engines, Comms and Data Networks and Space Launch and Recovery Systems. This will be achieved through business opportunities such as improving our understanding of the drivers of failure in complex systems and optimising infrastructure and instrumentation; [2] the optimisation of benefits and reduction of risks in major UK spending activities such as the £375Bn National Infrastructure Plan which includes major investments in National infrastructure and the UK Energy System. Extending the life of the infrastructure that supports our society could reduce the cost of such infrastructure by billions of pounds.

The American Society of Civil Engineers has estimated that the US needs to spend $1.1 trillion on its infrastructure by 2020 if it is to avoid losses of $1trillion a year on lost business and 3.5million jobs. The figures available for the UK vary but are broadly proportional to the US figures. Understanding this infrastructure in sufficient resolution to prioritise spending and establish new predictive techniques to avoid economic losses will require the application of complexity science. This network is focused on precisely this issue.

CES failure although rare can have catastrophic consequences. In the last 40 years there have been notable incidents that could be categorised as CES failures; Three Mile Island, Challenger Shuttle, Fukushima Daiichi and a number of aircraft failures that have led to significant loss of life. The financial crash that became evident in 2007 can also be characterised as a complex system failure.

In addition to the impact upon the design and management of CES, we must also consider the interaction between CES and natural complexity. For instance significant research is being undertaken to understand the impact of climate change upon national infrastructure but we are yet to develop the predictive capability to foresee such impacts. An example of the benefit of this emerging field is the Sandia National Infrastructure Simulation and Analysis Centre modelling that anticipated and characterised the impact of Hurricane Irene upon infrastructure when it made landfall in the USA in 2011. To address this challenge requires us to build a systemic (rather than reductionist) set of tools to understand and manage risk that will lead to the building of the requisite adaptive capacity to create resilience.