Error Coding Driven Synthesis of Combinational Circuits from Unreliable Components
With the advent of nanoelectronics, the reliability of the forthcoming circuits and computation devices is becoming questionable. Indeed, due to huge increases in density integration, lower supply voltages, and variations in the technological process, MOS and emerging nanoelectronic devices will be inherently unreliable. As a consequence, the nanoscale integration of chips built out of unreliable components has emerged as one of the most critical challenges for the next-generation electronic circuit design. To make such nanoscale integration economically viable, new solutions for efficient and fault-tolerant data processing and storage must now be invented.
This post-doctoral position aims at investigating innovative fault-tolerant solutions, at both device- and system-level, that are fundamentally rooted in mathematical models, algorithms, and techniques of information and coding theory. Investigated solutions will build on specific error correcting codes, able to provide reliable error protection even if they themselves operate on unreliable hardware. The goal is to develop the scientific foundation and provide a first proof-of-concept, as an essential condition for bringing about a paradigm shift in the design of future nanoscale circuits.
Developement of a simulation platform for the energy systems
The evolution of power systems towards smart-grids, including a high share of renewable generation which can be combined with storage systems, lead to an increased complexity for designing and optimizing these systems. This leads to a need for new modeling and simulation tools, which have to manage different energy sources, different energy vectors and different technologies for energy conversion. Moreover, such simulation tools will be used to optimize the system sizing and to design energy management strategies.
The objective of this project is to design the software architecture for the simulation platform, which will be in ad equation to the previously mentioned needs. Such software will be organized in order to maximize the transfer towards industrial partners. The software will be able to support multi-energy systems, and will leave the possibility for the user to implement its own component models or energy management strategies.
The project is focused on the simulation platform architecture, and on the architecture model. This architecture will be used as a base for the development of a software. The objective of the given project is not to cover all the applications but rather to validate the architecture through a given application.
Robust path-following solvers for the simulation of reinforced concrete structures
Path-following procedures are generally employed for describing unstable structural responses characterized by ``snap-backs'' and/or ``snap-troughs''. In these formulations, the evolution of the external actions (forces/displacements) is updated throughout the deformation process to fulfill a given criterion. Adapting the external loading during the calculation to control the evolution of the material non-linearities is helpful to obtain a solution and/or to reduce the number of iterations to convergence. This second aspect is of paramount importance, especially for large calculations (at the structural scale). Different path-following formulations were proposed in the literature. Unfortunately, an objective criterion for choosing one formulation over another for the simulation of reinforced concrete (RC) structures (in the presence of different and complex dissipation mechanisms) still needs to be made available. The proposed work will focus on the formulation of path-following algorithms adapted to simulate RC structures.
ACCELERATING a DSN SWEEP KERNEL ALGORITHM FOR NEUTRONICS BY PORTING ON GPU.
In the framework of the Programmes Transversaux de Compétences (PTC or literally Cross-XXX Programme), the DES/ISAS/DM2S/SERMA/LLPR and the CEA-DIF are both working on the porting of deterministic neutron transport codes on GPU.
The DM2S within the Energies Direction (DES) is responsible for research and development activities on the numerical methods and codes for reactor physics, amongst which the APOLLO3® code. The neutronics laboratory of CEA-DIF is responsible for developing tools for deterministic methods in neutronics for the Simulation programme.
These two laboratories are actively preparing for the advent of new generation of supercomputers where GPU (Graphical Processing Units) will be predominant. Indeed, the underlying numerical problems to be solved along with the working methodology as well as the conclusions and experience which will be obtained from such studies may be rationalised between both laboratories. Thus, this work has given rise to this postdoctoral position which will be common to both teams. The postdoctoral researcher will be formally based at SERMA at CEA Saclay, with nevertheless regular meetings with the CEA-DIF scientists.
The postdoctoral research work is to study the acceleration of a toy model of a 3D discrete ordinates diamond-differencing sweep kernel (DSN) by porting the code on GPU. This work hinges on porting experiments which have previously been carried by both teams following two different approaches: a ‘’high-level’’ one based on the Kokkos framework for DES and a ‘’low-level’’ approach based on Cuda for CEA-DIF.
Neutronic thermal-hydraulic coupling in heterogeneous Sodium Cooled Fast Reactor (SCFR)
Within the frame of ASTRID (Sodium cooled Fast Reactor) prototype development, update of calculation methodologies using new generation of codes benefiting from High Performance Computing (HPC) and advanced coupling capabilities is underway. These methods are expected to be integrated in ASTRID safety demonstration. In particular, development of coupled neutronics/thermal-hydraulics/fuel mechanics methodologies during accidental transients is underway.
Coupling Neutronics and thermal-hydraulics in double phase flow conditions (either sodium + vapor sodium or sodium + other gaz) can be used for:
• Loss of Flow transients (LOF, sodium + vapor sodium)
• Gas insertion transients.
This coupling is of special interest with cores strongly relying on axial leakage for safety consideration (like CFV cores [ICAPP11]).
The work proposed is to further develop the implementation of 3D coupling with state of the art CEA codes (APOLLO3, FLICA, CATHARE, TRIO etc.) to analyze the two type of transients stated above.
Development of Monte-Carlo methods for the simulation of radiative transfer: application to severe accidents
This post-doctoral subject concerns the development of Monte-Carlo ray-tracing methods for modeling radiation heat transfer in the context of severe accidents. Starting from a well-developed software framework for Monte Carlo simulation of particle transport in the context of reactor physics and radiation protection, we will seek to adapt existing methods to the problem of radiative heat transfer, in a high-performance computing framework. To do this, we will develop a hierarchy of approximations associated with radiative heat transfer that are intended to allow the validation of simplified models implemented in the context of the numerical simulation of severe accidents in nuclear reactors. Focusing on algorithm and simulation performance, this work is intended to be a "proof of principle" of the possible software mutualization around the Monte-Carlo method for particle transport on the one hand and radiative heat transfer on the other hand.