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.
Nonlinear ultrasonic testing for the assessment of adhesive bonding properties
The CEA-LIST carries out Non Destructive Testing (NDT) projects in partnership with various industrial sectors. A strong collaboration with Airbus Group Innovations (AGI) had led to a common entity through the NDT laboratory for Aeronautics Applications (LC2A).
With the increasing portion of composite materials in the aerospace industry, assessment of the adhesive bonding properties of such composite structures is a key issue. Various aspects could decrease the quality of bonding, such as the surface contamination, non-optimal thermal cycle or external mechanical stresses. However, conventional NDT techniques are often not sensible to such damages in the adhesive bonds.
Non-linear ultrasonic methods such as wave mixing, harmonic generation or non- linear imaging appear as promising techniques to detect kissing bonds and pre-damaging that could occur in adhesive bonds. The objective of this postdoc position is to develop NDT innovative solutions for the assessment of the adhesion quality by means of experimental techniques based on such non-linear methods.
This post-doc position will be carried out in the framework of an international research program on the adhesion bonding. The candidate will work in the NDE laboratory for Aeronautics Applications located in Toulouse. Strong skills in experimental physics, instrumentation, and non-linear ultrasonics would be appreciated.
Innovative modeling for technology-design-system co-optimization
The post-DOC will support the device modeling part of a research project investigating new methodologies for system and circuit optimization with the aim of achieving a better integration between the knowledge of the detailed characteristics of a specific technology, the circuit-design methodology and the system architecture. The practical goal is to leverage the existing multi-disciplinary know-how for benchmarking of system and technologies to advance the analysis past the usual PPA, PPAY and PPAC approaches that are commonly deployed in such cases.
In more detail, the post-DOC will develop "pre"-spice models for actives and passives which will constitute the basic bricks for the optimization methodology developed in the overall project. Active device modeling will have a starting point in the works of EPFL based on the analytical expression of invariants such has the inversion coefficient.
Ultra Low Power RF Communication Circuit and System Design for Wake-Up Radio
Today, there is a strong demand in developing new autonomous Wake-Up radio systems with tunable performances and independent clocking system. The objectives of the proposed contract it to exploit the capacity of CMOS FD-SOI technologies to develop such devices, improving power consumption and RF performance above the state of the art, thanks to the natural low parasitic and tuning capacity through back biasing of the FD-SOI . A particular attention will be paid to the development of a new power efficient, fast settling, frequency synthesis system.
The chosen candidate will be involved both in RF system and circuit design, with the support of the experienced RF System & Design team.
2D materials for Contacts and Gate stacks for advanced CMOS applications
Transition Metal Dicalchogenides (TMDs) have displayed interesting properties in numerous fields of nanotechnoogy (CMOS, memory, sensors, photonics etc.), and emerge as promising materials thanks to their functional properties and potential for co-integration, facilitated by their intrinsic features (van der Waals materials). However, their applicative impact remains uncertain due to the challenge of developing their processing in a standard nanoelectronics environment while maintaining a good control of their fundamental properties. The candidate will quantify the electrical properties of various 2D materials in test structures derived from a silicon technology baseline (TLM, Cross-Bridge Kelvin Résistors, MOS capacitors), in order to provide guidelines for device prototyping.
Specifically, the primary aim is to assess the interest of these materials as interface layers rather than for transport, for improving:
- The contact resistivity via Fermi-level depinning.
- Control by the Gate over the inversion charge in the channel via a negative differential capacitance effect.
Microfluidic cell encapsulation
The Laboratory of Biology and Microfluidic Architecture is looking for a candidate to establish a new class of microfluidic devices for cell encapsulation using robust, industry-compatible materials. The laboratory is located in the Microtechnologies for Biology and Healthcare Division of LETI, focused on the development of micro and nanotechnologies for applications in the fields of medical imaging, security, in-vitro diagnostic, nanomedicine, medical devices and environment monitoring. LETI is a research institution focused on creating value and innovation through technology transfer to its industrial partners. It specializes in nanotechnologies and their applications, from wireless devices and systems, to biology, healthcare and photonics.
Design of a power integrated circuit using GaN on Si, characterization, implementation.
The objective is to propose an innovative solution to supply low voltage electronics (3 to 12VDC) or to charge accumulators, using industrial alternating voltages (230VAC / 400VAC). This type of device should benefit greatly from the contribution of integrated passive technologies and the possibilities offered by the ASICs developed at Leti, in particular GaN ASICs. This research program is part of the Leti’s ’power roadmap’. From the state of the art and concepts envisaged by CEA researchers, the post-doctoral student will have to imagine an original solution, to design it and then to characterize the prototype. The research program involves other academic partners, which allows the post-doctoral student to immerse himself in an upstream research context. An industrial application has been identified. The post-doctoral student will be encouraged to enrich the subject with additional functions in the control (regulation) at very high frequency, the transmission of isolated signals via the converter or any other proposals.
Ge-on-Insulator (GeOI) substrates for photonics
The induction of tensile strain in intrinsic and doped Germanium (Ge) is one approach currently explored to transform the Ge indirect bandgap into a direct one. To take full advantage of Ge, we study the Ge CMOS photonics platform with Ge-on-Insulator (GeOI) structure, which enables strong 2D optical confinement in the Ge photonic-wire devices. One recent study in our lab showed the interest of a method of incorporation of mechanical stress into Ge, one of the essential ingredients of the laser. In particular, the method could be applied to the massive Ge, making compatible gap direct and crystalline quality.
Post-doc objectives : Development of GeOI substrates from massive Ge donors with tensile strain inside the Ge film. These developments will be realized from the existing Smart Cut / thinning processes, combined with technological steps to overcome their current limits (SAB bonding). The substrates obtained will be characterized to determine their state of deformation as well as their damage (Raman / XRD) and final GeOI substrates will be provided to the application laboratories for the production of photonic components.