Frequency tunable elastic plate wave resonators and filters
The increasing number of frequency bands having to be dealt with in mobile phone systems require a huge number of band pass filters in such systems. In this context, the capability to provide frequency tunable resonators and filters is seen as a key enabling element in future wireless transmission systems.
CEA-LETI has been working for more than 10 years on the development of resonators and filters exploiting the propagation of guided elastic waves in piezoelectric thin films. It has also proposed several concepts for frequency agile resonators and filters.
The purpose of this post-doc will be to further develop these ideas and to apply them to the design of demonstrators matching realistic specifications. In collaboration with the other member of the project team, more focused on fabrication in clean rooms, the candidate will propose innovative structures demonstrating frequency tuning of reconfigurability, and will take in charge their electrical characterization.
Wireless biological sensor using 2D materials (Graphene , Molybdenium disulfide)
The main goal of the post-doctoral position is the fabrication of a biological sensor using 2D materials and that can be remotely addressed thanks to a RF antenna simultaneously fabricated alongside the biosensor.
The post-doctoral associate will be in charge of the fabrication and characterization of the prototype. Starting from well-designed modelling, he/she will first establish a design architecture for the sensor and RF antenna. Once designed and sized, the post-doctoral associate will adapt existing transfer protocol of 2D materials to develop an innovative fabrication process for the sensor. He/she will then fabricate the first prototypes of the sensors. Consecutively he/she will validate first the remote addressing of the sensor via the RF antenna. Secondly he/she will lead biodétection tests to assess the sensitivity of the fabricated sensors. Finally, he/she will try to integrate Transition Metal Di-chalcogenides 2D materials (such as MoS2) to graphene sensors inside a hybrid 2D materials biological sensor. The goal here will be to boost operational sensitivity.
Conversational Agent for Medical Serious Games
The LVIC laboratory participates in a research project which aims to develop innovative tools for teaching medical students. The training will be done through serious games of second generation, in which the learner can interact directly with the environment:
- immersed in a 3D environment with a Virtual Reality Head Mounted Display and motion detection,
- with natural and ecological handling of the environment (instruments, patient …),
- and a voice interaction with conversational and emotional avatars.
The multimedia team of LVIC laboratory is involved in the project to develop tools allowing students to interact in natural language with conversational avatars.
In this context, the post-doctoral researcher will be in charge of:
- studying the state of art of conversational agents;
- understanding and mastering the technological components of the laboratory language processing;
- proposing and developing a dialogue system allowing interaction in natural language with conversational avatars of the project.
Application of ontology and knowledge engineering to complex system engineering
Model-Based System Engineering relies on using various formal descriptions of the system to make prediction, analysis, automation, simulation... However, these descriptions are mostly distributed across heterogeneous silos. The analysis and exploitation of the information are confined to their silos and thereby miss the big picture. The crosscutting insights remain hidden.
To overcome this problem, ontologies and knowledge engineering techniques provide desirable solutions that have been acknowledged by academic works. These techniques and paradigm notably help in giving access to a complete digital twin of the system thanks to their federation capabilities, in making sense to the information by embedding it with existing formal knowledge and in exploring and uncovering inconsistencies thanks to reasoning capabilities.
The objective of this work will be to propose an approach that gives access to a complete digital twin federated with knowledge engineering technologies. The opportunities and limits of the approach will be evaluated on industrial use cases.
Charge to spin conversion in HgTe topological insulators
The intrinsic spin-momentum locking of Dirac fermions at the surface or interface of topological insulators opens the path towards novel spintronic effects and applications.
Strained HgTe/CdTe is a model topological insulator and a very good candidate to design and demonstrate new spintronic devices exploiting the very large charge to spin conversion efficiency expected for such 2D systems. This postdoc position aims at realizing the first demonstration of the direct charge to spin conversion in topological HgTe nanostructures and use this demonstration as a building block for spin based logic elements.
New reference radiation field for radioprotection in the range of Cs-137 et Co-60 using an electrostatic electron accelerator
During the last years, LNHB has started and realized a research program in order to produce a reference photon radiation field for the radioprotection needs at high energies (~6 MeV) using its medical electron accelerator Saturne 43. For this purpose, a target and its appropriate flattering-attenuating filter have been designed by LNHB in order to produce the required photon field.
Nowadays there is no existing device able to produce radiation fields from an accelerator in the Cs-137 and Co-60 equivalent energy range. In order to achieve this, one needs the technology to construct and properly use absolute dosemeters for photons (cavity ionization chambers), to determine the right target-filter assembly allowing the production of the required photon field and to accurately calculate the conversion factors from air-kerma to operational quantity which is the dose-equivalent using the spectral distribution at the calibration position.
The candidate will participate in the construction of cavity ionization chambers needed for the characterization in terms of dose-equivalent of radiation field obtained from the electron accelerator and to the on-site measurements. He(She) will also be in charge with Monte-Carlo simulations in order to optimize the target-filter assembly used to produce the reference photon field from an electrostatic accelerator.
Software and hardware combined acceleration solution for operations research algorithms
The purpose of the study is to prepare the next generation of OR solvers. We will study the hardware acceleration possibility based on FPGA to run some or all of the OR algorithm. The blocks for which such a solution is not effective can be parallelized and executed on a standard computing platform. Thus, the proposed runtime correspond to a standard computing platform integrating FPGA. To access to this platform we require a set of tools. These tools should provide features such as (a) analysis and pre-compiling an input or problem or sub-problem of OR, (b) HW / SW partitioning and dedicated logic optimization and finally (c) generating an software executable and a bitstream.
The first step will be to find OR algorithms that are well suited for hardware acceleration. We then propose a HW / SW partitioning methodologies for different classes of algorithms.
The results will be implemented to lead to a compilation prototype starting from an OR instance and generating a software executable and a bitstream. Theses results will be implemented and executed on a computing platform integrating FPGA to evaluate the performance gain and the impact on the energy consumption of the proposed solution.
Simulation of PEMFC flooding phenomena
The proton exchange membrane fuel cell (PEMFC) is now considered as a relevant solution for carbon-free electrical energy production, for both transport and stationary applications. The management of the fluids inside these cells has a significant impact on their performance and their durability. Flooding phenomena due to the accumulation of liquid water are known to impact the operation of the cells, causing performance drops and also damages that can be irreversible. With the use of thinner channels in ever more compact stacks, these phenomena are becoming more and more frequent. The objective of this post-doc is to progress in the understanding of flooding in PEMFCs. The work will consist in analyzing the link between the operating conditions, the design of the channels and the materials used in the cell. It will be based on a two-phase flow modeling approach at different scales, from the local scale at the channel-rib level, up to, via an upscaling approach, the level of the complete cell. The study will also be based on numerous experimental results obtained at the CEA or in the literature.
High entropy alloys determination (predictive thermodynamics and Machine learning) and their fast elaboration by Spark Plasma Sintering
The proposed work aims to create an integrated system combining a computational thermodynamic algorithm (CALPHAD-type (calculation of phase diagrams)) with a multi-objective algorithm (genetic, Gaussian or other) together with data mining techniques in order to select and optimize compositions of High entropy alloys in a 6-element system: Fe-Ni-Co-Cr-Al-Mo.
Associated with computational methods, fast fabrication and characterization methods of samples (hardness, density, grain size) will support the selection process. Optimization and validation of the alloy’s composition will be oriented towards two industrial use cases: structural alloys (replacement of Ni-based alloys) and corrosion protection against melted salts (nuclear application)
Apprenticeship Learning Platform deployment for industrial applications
This project aims at developing a demonstrator that integrates state-of-the-art technologies and improve it on a use-case representative of the industrial world.
The demonstrator will consist in a robotic / cobotic arm coupled to an acquisition sensor (RGBD type). This device will be positioned in a workspace made of a rack / shelf containing objects / pieces of various shapes and qualities (materials, densities, colors ...) in front of which will be placed a typical conveyor prototype of industrial installations. The type of tasks expected to be carried out by the demonstrator will be "pick and place" type tasks where an object will have to be identified in shelf and then placed on the conveyor.
This type of demonstrator will be closer to the real industrial conditions of use than the "toy" examples used in the academic field.
This demonstrator will focus first on the short-term effectiveness based on state of the art technologies for both hardware and software, for a use case representative of the industrial world.
At first, it will thus be less focused on the evolution of the algorithms used than on the adaptation of the parameters, the injection of knowledge a priori dependent on the context making it possible to reduce the high-dimensional input space, etc.