Application of the Hybrid-High-Order (HHO) method for the treatment of non-local effects in crystal plasticity via a micromorph approach
Describing the behavior of materials at the crystalline scale is the subject of much academic research, and is of growing interest in industrial R&D studies. Classically, this description is based on behavior laws describing the local evolution of the material's microstructural state: (visco-)plastic deformation, dislocation density, etc.
The main driving force behind this evolution is resolved shear stress, the projection of the stress tensor on the slip systems.
The formalism of these local constitutive equations (as opposed to non-local constitutive
equations discussed hereafter) is now well established, whether we are considering
infinitesimal or finite transformations, and benefits from special support within the MFront code generator. Thanks to MFront, those constitutive equations can be used in various mechanical solvers at CEA (Manta, Cast3M , Europlexus , AMITEX_FFTP ) and EDF
(code_aster, Manta, Europlexus ).
However, the use of local constitutive equations does not allow to account for many effects.
The aim of the post-doc is to develop a robust numerical strategy for reliably solving
structural problems using non-local crystal plasticity laws, and guaranteeing the
transferability of the constitutive equations between the CEA and EDF codes.
Attack detection in the electrical grid distributed control
To enable the emergence of flexible and resilient energy networks, we need to find solutions to the challenges facing these networks, in particular digitization and the protection of data flows that this will entail, and cybersecurity issues.
In the Tasting project, and in collaboration with RTE, the French electricity transmission network operator, your role will be to analyze data protection for all parties involved. The aim is to verify security properties on data in distributed systems, taking into account that those induce a number of uncertainties.
To this end, you will develop a tool-based methodology for protecting the data of power grid stakeholders. The approach will be based on formal methods, in particular runtime verification, applied to a distributed control system.
This postdoc position is part of the TASTING project, which aims to meet the key challenges of modernizing and securing power systems. This 4-year project, which started in 2023, addresses axis 3 of the PEPR TASE call “Technological solutions for the digitization of intelligent energy systems”, co-piloted by CEA and CNRS, which aims to generate innovations in the fields of solar energy, photovoltaics, floating wind power and for the emergence of flexible and resilient energy networks. The targeted scientific challenges concern the ICT infrastructure, considered as a key element and solution provider for the profound transformations that our energy infrastructures will undergo in the decades to come.
The project involves two national research organizations, INRIA and CEA through its technological research institute CEA-List. Also involved are 7 academic laboratories: G2Elab, GeePs, IRIT, L2EP, L2S and SATIE, as well as an industrial partner, RTE, which is supplying various use cases.
Correlative X-ray and ToF-SIMS tomography Data fusion of 3-D data sets from X-ray and ToF-SIMS tomography
The nanocaracterisation platform of the CEA Grenoble has recently installed 2 state-of-the-art tools for 3-D imaging with 100 nm resolution: X-ray tomography in a SEM and time of flight secondary ion mass spectrometry (ToF-SIMS) assisted by focused ion milling (FIB). X-ray tomography delivers non-invasive 3-D images of the internal morphology of an object whilst ToF-SIMS is able to map the local composition in 3-D. We aim to combine the two techniques to perform quantitative 3-D investigations of objects such as copper pillars for microelectronics or silicon electrodes for Li battery applications.
The proposed research subject is data analysis orientated. Some simulation work may be performed to implement and test existing 3-D data fusion methods with a view to adapting and improving them. The candidate will assist with the experimental measurements and be responsible for treating the data with the chosen protocols. The candidate should be pragmatic, at ease with applied mathematics and have good programming skills. These will be essential in understanding and manipulating the fusion and reconstruction algorithms, from the simplest, to the increasingly advanced (prior information, superiorisation, Bayesian fusion)
The candidate will have completed a PhD in physics and have good computer (Python, Matlab, C) and image treatment skills, or a PhD in mathematics/computational science with an interest in applications. The candiate will need to interface with a multidisciplinary team, and be receptive to new ideas. The candidate will be proficient in both written and spoken English in order to communicate with the team and to disseminate their results in articles or at conferences.
Electro-optical characterisation for Vis-IR active devices
With the Integration of Heterogeneous Components Department, the Lab of Technologies and Components for Visualisation (DIHS/LTCV) develops OLED devices. One of its main topics is aimed at producing hybrid OLEDs, hybrid standing for the mix of deposition techniques : wet and evaporation. Target applications come from micro displays to photodetectors via lighting.
For the development of hybrid OLEDs, DIHS/LTCV lab is looking for a Post_doc specialised in Organic Electronic to work in a fundamental research project. You will be in charge of stack development and of the characterisation method development for OLEDs devices.The optimisation of the cavity will be done based on the physical parameters of the different layers.
At the same time, IV, CV and photoluminescence analyses will be adapted in visible and IR range.
Finally, the layers interface study by impedance spectroscopy and Hall effect will be done.
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.
Development and characterization of concentrator photovoltaic (CPV) receivers for high-efficiency CPV modules
Concentrator photovoltaics (CPV) arises as a promising technology capable of economically justify the use of highly efficient (and highly expensive) monolithically stacked multijunction solar cells (MJSC). CPV takes advantage of low-cost optical elements, such as mirrors or lenses, to capture the sunlight and concentrate it into small-size cells, exchanging solar cell surface by optical elements. This technology, which is at an industrial stage, uses state-of-the-art triple junction (3J) solar cells with efficiencies up to 45%.
The postdoc position here proposed will deal with novel architectures of CPV receivers conceived from high-efficiency MJSC that will be integrated in next-generation CPV modules. The research engineer will also need to learn how to characterize these systems, for which he/she will use the tools available at the CPV Lab at INES (CEA). Novel characterization techniques may also be required.
The candidate must have a M.S. in Physics or Engineer with specialization on solid state physics, electronics, electrical engineering, mechatronics or similar. He/she must be a PhD, preferably in the field of photovoltaics and particularly on CPV. Good language skills and laboratory experience are required.
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.