Synchronous design of avionic applications based on model refinements

International audienceIn this article, we address the design of avionic applications based on an approach, which relies on model refinement. This study is done within the synchronous framework, which has solid mathematical foundations enabling formal methods for specification, verification and analysis, transformations, etc. In the proposed approach, we first consider a functional description of a given application using the SIGNAL language. This description is independent of a specific implementation platform. Then, some transformations that fully preserve the semantics of manipulated SIGNAL programs are applied to the description such that a representation reflecting an integrated modular avionics architecture results

Heterogeneous models and analyses in the design of real-time embedded systems - an avionic case-study

The development of embedded systems according to Model-Driven Development relies on two complementary activities: system mod- eling on the one hand and analysis of the non-functional properties, such as timing properties, on the other hand. Yet, the coupling be- tween models and analyses remains largely disregarded so far: e.g. how to apply an analysis on a model? How to manage the analysis process? This paper presents an application of our research on this topic. In particular, we show that our approach makes it possible to combine heterogeneous models and analyses in the design of an avionic system. We use two languages to model the system at di erent levels of abstraction: the industry standard AADL (Ar- chitecture Analysis and Design Language) and the more recent implementation-oriented CPAL language (Cyber-Physical Action Language). We then combine di erent real-time scheduling analy- ses so as to gradually de ne the task and network parameters and nally validate the schedulability of all activities of the system

System-level Co-simulation of Integrated Avionics Using Polychrony

International audienceThe design of embedded systems from multiple views and heterogeneous models is ubiquitous in avionics as, in partic- ular, different high-level modeling standards are adopted for specifying the structure, hardware and software components of a system. The system-level simulation of such composite models is necessary but difficult task, allowing to validate global design choices as early as possible in the system de- sign flow. This paper presents an approach to the issue of composing, integrating and simulating heterogeneous mod- els in a system co-design flow. First, the functional behavior of an application is modeled with synchronous data-flow and statechart diagrams using Simulink/Gene-Auto. The system architecture is modeled in the AADL standard. These high- level, synchronous and asynchronous, models are then trans- lated into a common model, based on a polychronous model of computation, allowing for a Globally Asynchronous Lo- cally Synchronous (GALS) interpretation of the composed models. This translation is implemented as an automatic model transformation within Polychrony, a toolkit for em- bedded systems design. Simulation, including profiling and value change dump demonstration, has been carried out based on the common model within Polychrony. An avionic case study, consisting of a simplified doors and slides control system, is presented to illustrate our approach

SOA-Based Aeronautical Service Integration

Space scienc

Chapter SOA-Based Aeronautical Service Integration

Space scienc

TRANSIENT THERMAL PERFORMANCE ENHANCEMENT OF PHASE CHANGE MATERIALS THROUGH NOVEL PIN ARRANGEMENTS UNDER VARIED GRAVITY CONDITIONS

This thesis presents a comprehensive examination of encapsulation techniques and performance enhancement strategies for Phase Change Materials (PCMs) in the thermal management of spacecraft avionics. This research contributes to optimizing PCM applications in spacecraft through historical analysis, transient thermal performance enhancement, and computational studies. The first chapter explains the significance of PCMs in passive thermal management since the beginning of space-age technology, it underlines the low thermal conductivity of PCMs and the necessity of incorporating materials with high thermal conductivity, such as metal foams, to improve heat transfer. It also discusses various advancements in PCM research for spacecraft thermal management applications like the shape-stabilized PCMs and also explains in details various encapsulations techniques for PCMs. This chapter also reflect upon the various efforts done by space agencies (NASA, ESA and ISRO) towards understanding the feasibility of phase change materials for spacecraft thermal management applications. It also examines the effect of various parameters such as direction of heat flow and orientation of PCM to obtain tailored heat transfer research which can be leveraged by phase change materials for effective thermal management of spacecraft avionics. The subsequent chapter examines the transient thermal performance of a particular PCM, RT82, using novel pin arrangements. Through the strategic placement of fins, thermal conductivity and heat transfer surface area are enhanced. This study investigates numerically the melting characteristics under microgravity, terrestrial gravity, and hypergravity. This study focuses on the improvement in thermal performance brought about by fin integration under differing gravitational conditions. The final chapter explores computational studies concentrating on the geometrical optimization of PCM encapsulation in Triplex Tube Heat Exchangers (TTHX) utilizing novel annular-fin configurations. This research examines the impact of fin shape, size, and positioning on the thermal characteristics of PCM. It identifies encapsulation geometries that facilitate vortex-like melting patterns, thereby accelerating PCM melting rates. In addition, it evaluates the heat transfer performance of these configurations under varying gravity conditions, elucidating the physics underlying the enhancement of melting performance. In conclusion, this thesis demonstrates that judicious encapsulation techniques and geometric optimisation significantly enhance the thermal management effectiveness of PCMs in spacecraft. This research paves the way for innovation in spacecraft thermal management systems employing PCMs by interweaving historical context with performance enhancement strategies and computational insights