Uncertainty Management of Electromagnetic Protection on Systems – UMEPS

Uncertainties treatment has been formalized in different books and a software example is the Openturns framework. Implemented techniques have already been used in mechanical design. UMEPS proposes those techniques to be introduced in the electromagnetic protection trade. In other respects, electromagnetic modeling is widely spread within aerospace integrators but numerical models are often time consuming. So, in their former state they are not well adapted to uncertainties treatment even if computer performance is always growing up. Then, it is necessary to get lighter models which will ease uncertainties treatment. The project proposes linear and non linear model reduction

To be able to run probabilsitic studies, one of the first project results is to perform a state of the art of current margins and identify the most representative parameters that play a role in electromagnetic protection. In a second step, variability of those parameters is realized counting on expertise or available measurements. Concerning linear model reduction, significative scientific achievements are realized, for example by introducing in reduced models distributed parameters such as surface impedance. Umeps targets also to spread methods and tools towards other industrial and academic (civil and defence industry) by two workshop organization. A guideline for uncertainties treatment in electromagnetism on complex systems is also a important result of the project

Umeps project perspectives is to deliver a strong and operative probabilistic methodology within EMC designers teams. A common vocabulary is proposed and helps decision making by a better margin control between electromagnetic levels and resources (equipment performance). It seems interesting to continue the effort in direction of partners working in avionic industry

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The UMEPS project aims to enhance the management of electromagnetic safety margins used to design the protections of a complex on-board system. Electromagnetic protections must fulfill a certain level of performance but without:
- overprotecting the system - this would lead to non optimized mass and costs
- oversizing the frequency of maintenance operations - this would produce excessive operating costs and low availability rate.

When a new program is under development, uncertainties (lack of information, variability of certain parameters, ageing,...) are taken into account based on deterministic analysis and often on worst case analysis. This deterministic approach also relies on cumulated experience and feedback over years.
Nevertheless, risks related to the uncertainty sources can not be quantified and thus no precise measurement of reliability or availability of the system can be performed.

In this context, it seems necessary to develop an approach that will able to establish the relation between uncertainty sources, imposed margins and envisaged risks. An enhanced management of imposed margins will allow to manufacture better systems and guarantee a quantified degree of reliability. This is precisely the aim of UMEPS that will use recently developed probabilistic methods.

The UMEPS project deals with 4 main challenges:

- Quantify and analyze the uncertainty sources that play a role in the determination of electromagnetic constraints that guide the design of systems in the aeronautic and spatial sectors.
- Develop model order reduction techniques in order to apply probabilistic methods to treat uncertainty over geometrical properties and material physical properties
- Demonstrate that the probabilistic methodology proposed, applied to lightning indirect effects, high intensity radar field or internal EMC is operative from an industrial point of view.
- Establish and promote inside the EMC community the probabilistic methodology applied to protection/shielding of on-board systems (guideline, workshop).

The main result of UMEPS is a Guideline for the management of uncertainties in electromagnetic protection of systems. This result will be shared through a workshop gathering the main actors of this discipline in France (DGA, ONERA, THALES, AIRBUS...)

UMEPS is developed by complementary partners: two French industrial societies (ASTRIUM-ST, EUROCOPTER), holding 25% activity, an industrial research laboratory (EADS IW) for 25%, a CNRS laboratory (AMPERE) for 30% and an SME (IMACS) for 20%.

The primary industrial scope of UMEPS are both the aeronautic and space sectors , because of the high constraints related to mass optimization. Nevertheless applications to automobile or telecom applications where cost constraints are predominant should be straightforward.