System of Systems (SoS) are everywhere, either created and directed by an organization or simply emerging to fulfill a need. SoS consist of many independent Constituent Systems (CS) with their own life cycles and behavior. One of the big challenges with studying SoS is building models to support the analysis of these large complex systems. For existent SoS, it may be tempting to use available models from subsequent levels and connect them in a common framework, rather than creating new models tailored for the SoS analysis. Typically, the already existing models often have a high level of fidelity and have been created from a certain point of view to best fit its purpose. This paper shows that a framework with higher fidelity models on Sub-Systems (SS) level will impact the performance on SoS level but also take longer time to converge and thus need more simulations in order for the results to be trusted. With an holistic approach to the development of SoS, we use hierarchical integration of CS and SS models to provide inputs to the simulation on SoS level. Using maritime Search and Rescue (SAR) as a case study, the mission performance of two aircraft searching for a lost life raft through Agent Based Simulation (ABS). Two cases are compared where one of them has a higher fidelity representation of the sensor model. Through the case study it is possible to investigate the impact of model fidelity on the SS level to the simulation results on SoS level. The two cases simulate the same scenario but still show a difference in mission performance. A convergence analysis show that with the the High Fidelity Models (HFM) the simulation takes slightly longer to converge. This paper is the beginning of a multi-fidelity model library that will be used to explore the impact of model fidelity on all the levels of SoS and from that find general methods for choosing model fidelity when analyzing SoS.

The aircraft design process has several phases, the first of which is conceptual design. In this phase, models describing an aircraft concept’s properties are used to evaluate its function and identify designs that meet given requirements. Fighter aircraft are generally expected to be capable of communicating, delivering munitions and gathering data about their environment to gain situational awareness. The ability to avoid detection by hostile sensors can also be important, depending on the aircraft’s role.

The design process of the aircraft itself has usually focused on an aircraft’s flight performance and ability to carry loads, e.g. munitions and extra fuel. While acceleration, rate of turn, maximum speed, and operational range are important parameters, the success of military missions also depends on sensor capabilities and signature levels. However, sensor installation and signature reduction measures can affect the aircraft and its flight performance. Whether an aircraft concept fulfills the requirements given is evaluated using simulations in appropriate scenarios. The concept’s performance is assessed using models of aircraft properties, weapon properties, sensor capabilities and signature levels. Models of the aircraft properties are usually connected dynamically, and respond to changes in such things as the size of the concept. However, sensor and signature models are often the result of a separate optimization process and are only statically connected to the aircraft model. The complete aircraft model can be improved by introducing sensor and signature models that dynamically describe both their functions, and their impact on the aircraft. Concurrent design of all the aircraft properties may improve the quality of results from scenario simulations. When models used in simulations contain parameters coupled to each other, analysis of the resulting data is particularly important because that is what supports a decision-maker’s design choice.

Sensor and signature models, in some cases combined with flight performance models, have been used to test methodologies intended for use in conceptual aircraft design. The results show that even seemingly simple models can produce results that can make a significant contribution to the aircraft design process.

Det första steget vid flygplansutveckling är konceptfasen, där alternativa förslag på flygplan representeras av modeller som beskriver det tänkta flygplanets egenskaper. Modellerna används i simuleringar som genomförs i olika scenarion, för att utvärdera och rangordna de olika flygplanskonceptens förmågor. För stridsflygplan är det viktigt att kunna manövrera och leverera vapen såväl som att skaffa och upprätthålla en situationsuppfattning. Beroende på flygplanens roll i uppdraget kan det också vara en prioritet att undgå upptäckt från fiendens sensorer.

Konceptsfasen är vanligtvis inriktad mot flygplanets prestanda och kapacitet att bära last, exempelvis extra bränsle och vapen. Förmågan att framgångsrikt genomföra ett militärt uppdrag beror på egenskaper som har att göra med svängprestanda, acceleration, topphastighet och räckvidd såväl som sensorernas egenskaper och flygplanets signaturnivå. Simuleringar av scenarion med modeller av flygplanets egenskaper, vapenprestanda, sensoregenskaper och signaturnivåer, möjliggör värdering av ett flygplanskoncepts förmåga att genomföra sitt uppdrag på ett tillfredsställande sätt. De modeller som beskriver flygegenskaperna är vanligtvis sammankopplade och ändringar i exempelvis flygplanets storlek påverkar alla modeller. Sensor- och signaturmodeller, är däremot ofta ett resultat av en separat konstruktionsprocess och inte kopplade till exempelvis flygegenskaper. Genom att införa modeller av sensorprestanda och signaturnivåer som är dynamiskt kopplade till flygplanets modeller finns det möjligheter att förbättra konceptanalysen. Resultatet ger möjligheter att få mer fullständigt resultat från simuleringarna i scenarion, vilket i sin tur ger beslutsfattare ett bättre underlag.

I den här avhandlingen presenteras modeller av sensorer och signaturnivåer, avsedda att användas vid konceptkonstruktion av flygplan. Vissa av modellerna är kopplade till modeller för flygprestanda. Resultaten visar att även till synes enkla modeller ger resultat som kan utgöra ett användbart bidrag till konstruktionsprocessen.

A concept called Military Utility is proposed for the study of the use of technology in military operations. The proposed concept includes a three-level structure representing key features and their detailed components. On basic level the Military Utility of a technical system, to a military actor, in a specific context, is a compound measure of the military effectiveness, of the assessed technical system's suitability to the military capability system and of the affordability. The concept is derived through conceptual analysis and is based on related concepts used in social sciences, the military domain and Systems Engineering. It is argued that the concept has qualitative explanatory powers and can support military decision-making regarding technology in forecasts, defense planning, development, utilization and the lessons learned process. The suggested concept is expected to contribute to the development of the science of Military-Technology and to be found useful to actors related to defense.

Faceted conformal antenna arrays are analyzed with the uniform theory of diffraction (UTD). Parameters such as mutual coupling, scattering parameters, isolated and embedded element patterns are calculated.

A ray tracing algorithm for handling rays on a faceted surface, which is needed for the UTD calculations, is also described.