Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

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Evaluation of photobiomodulation properties to optimize organ transplant

Clinatec (LETI)

Clinatec (LETI)

01-11-2020

SL-DRT-20-1236

cecile.moro@cea.fr

Health and environment technologies, medical devices (.pdf)

Grafts do not always meet the eligibility criteria, thus limiting the number of grafts available. One way to increase this number would be to repackage "borderline" grafts and / or protect them from the damage inherent in the transplantation protocol (in particular due to the ischemia-reperfusion processes), and to promote the phenomena of revascularization and scarring. An innovative light therapy, photobiomodulation, could optimize and protect these grafts. Here we wish to assess the therapeutic potential of photobiomodulation in several preclinical transplantation models. Complementary cell biology studies will allow a better understanding of the mechanisms used. This research program will cover several therapeutic areas, and will be carried out in conjunction with multidisciplinary research teams outside the CEA.

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Reliability of power amplifiers: modeling, design and test strategies

Département Composants Silicium (LETI)

Laboratoire de Caractérisation et Test Electrique

01-10-2020

SL-DRT-20-1251

alexis.divay@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

With the rise of 5G, RF and millimeter circuits are increasing in the telecommunications sector. In the reception / transmission chain, the power amplifier (PA) is a key element and it is critical to the proper functioning of transmissions. The reliability of the latter is an important element because the RF excursions at the terminals of the device are strong and the signal shapes are complex, bringing dynamic aging mechanisms into play. In this context, the designer must rely on aging simulation tools to be able to correctly size his circuit. One of the first objectives of the thesis is to better understand the aging mechanisms put into play at the CMOS level through stress campaigns in DC and in broad signal RF on a Load-Pull bench. The transistors studied will be MOS with fine oxide as well as devices optimized for high power (DMOS). Then, different topologies of the power stage will be studied in order to correlate the design with a possible gain in reliability. Finally, an in-situ monitoring system for the degradation of the device will be proposed to compensate for performance losses or to alert in the event of an imminent failure.

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Micro-concentration photovoltaics for space

Département des Technologies Solaires (LITEN)

Laboratoire Photovoltaďque ŕ Concentration

01-11-2020

SL-DRT-20-1254

philippe.voarino@cea.fr

Solar energy for energy transition (.pdf)

Originally, silicon solar cells developed for space applications following their first use in 1958, with efficiency around 7-8%. Nowadays, the GaInP/GaAs/Ge triple-junctions solar cells, offering higher efficiencies and higher radiation hardness (electrons & protons), are the mainstream solution for powering space missions. However, the cost remains a significant fraction of space solar arrays based on this cell technology. On the other hand, Concentrator PhotoVoltaics (CPV) is a proven approach, developed mainly for terrestrial applications, to reduce the amount of expensive III-V cells, utilizing either reflective or refractive elements to focus the sunlight onto a much smaller solar cell area, while boosting the conversion efficiency. Thus, the use of CPV for space application appears as a promising performance/price tradeoff, which in addition can be a mission enabler for deep space low irradiation environment1. Yet, CPV for space still need to tackle the challenges of mass, reliability in harsh environment, heat dissipation and optical losses. The development of a new generation of micro-concentration photovoltaics solutions, µ-CPV2, have the potential to address many of these issues at once. µ-CPV systems are based on sub-millimeter (< 1 mm˛) size solar cells, which enable both passive heat dissipation and compact optics. Recently, proof of concepts µ-CPV systems have shown efficiencies > 25% at low concentration and with large acceptance angles3. Within this context, this PhD offer will focus on an innovative & lightweight µ-CPV design addressing the key metrics of W/kg, W/m2 and W/m3, the cost. The scientific challenges associated concern the study and comprehension of degradation mechanism of materials and optical systems exposed to space environmental constraints (thermal cycling, UV, charged particles irradiations, etc.). The main objectives of this work are the following: - Definition of a smart µ-CPV cell & array design adapted for low/medium concentration in space, based on the laboratories expertise in the field & in depth literature review - Fabrication of µ-cells and development of materials and module fabrication/assembly processes - The final µ-CPV array performance will be optically/electrically characterized and its resilience to ageing tests will be studied. A loop on this iterative process will enable a fully optimized, manufactural, low cost and lightweight µ-CPV system array by the end of the PhD thesis. This work will bring scientific and technical insights on materials and optical systems behavior under space constraints, and thus will lead to communications, publications & patents. International collaboration: This PhD thesis will happen in the framework of a collaboration between CEA-LITEN (INES, Le Bourget du Lac, France) and Fraunhofer ISE (Freiburg, Germany). Strong interactions are foreseen between teams and PhD students of both institutes: joint roadmap, scientific exchange, training, etc. Expected Start: November 2020 ? 3 years duration References: 1 P.M. Stella, 34th Intersociety Energy Conversion Engineering Conference, (1999). 2 A. Ritou et., Sol. Energy 173, 789 (2018). 3 C.J. Ruud et al., Opt. Express 27, A1467 (2019).

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Basic Abstractions for consistent and auditable Byzantine tolerant distributed systems.

Département Ingénierie Logiciels et Systčmes (LIST)

Lab.systčmes d'information de confiance, intelligents et auto-organisants

01-10-2020

SL-DRT-20-1265

antonella.delpozzo@cea.fr

Artificial intelligence & Data intelligence (.pdf)

Data auditability, along with security and privacy, is recently gaining more and more importance with the advent of the General Data Protection Regulation (GDPR). Concisely, GDPR is a set of regulations, covering the entire lifecycle of personal data, which has a dramatic effect on the current Information Systems (IS), in particular distributed data storages and the emerging Blockchain technology. The objective of this doctoral thesis is to formalize the GDPR criteria in the context of distributed systems abstractions and to assess the feasibility of GDPR compliant distributed system solutions. The result of this thesis will be a more clear comprehension of the possibilities (in terms of new protocols) and impossibilities for next generation of GDPR compliant distributed abstractions.

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