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

PhD : selection by topics

Engineering science >> Instrumentation
15 proposition(s).

Wind turbulence effect on ventilation engineering

Département des Technologies Solaires (LITEN)

01-09-2017

SL-DRT-19-0036

xavier.faure@cea.fr

Ventilation systems in buildings, whether mechanical by extraction, mechanical by insufflation, natural or hybrid, are subjected to the effects of wind. Depending on the orientation of the outlet / inlet ports, the pressure conditions can substantially change the air change rates. A better understanding of the effects of wind and particularly the up to day neglected turbulence effects would allow a better understanding of the interactions with the ventilation systems and contribute to the development of tools for ventilation engineering (finer dimensioning Ventilation systems and development of hybrid ventilation strategies). The increasing energy performance of buildings, from the first regulations to now, brings ventilation systems to the forefront of equipment for regulating indoor ambiances from both an energy and health point of view. In the present subject, wind turbulence and pressure fluctuations generated inside the building will have to be considered with regard to the envelope leackage (and the dynamics of water diffusion within it), the times delay of ventilation devices and sources of internal pollutants. The identification of the effects contributing to or opposing the air renewal should consider the different balances between the mechanical and natural effects (aerodynamics and thermal) and their dynamics.

High voltage PV power plant

Département des Technologies Solaires (LITEN)

01-01-2019

SL-DRT-19-0060

jeremy.martin@cea.fr

Recent developments in high-voltage semiconductors with Silicon Carbide open up prospects for major innovations for PV power plant technologies. INES wishes to position itself on the feasibility of a rise in voltage of high power plants operating at a voltage above 1500V. Future technological innovations should allow a reduction in the cost per kWh produced (? / kWh). The objective of this work will be to evaluate the performance of high voltage photovoltaic systems within the limit of the voltage ratings of commercially available semiconductor switches (15kV). A second step will be to select the most interesting architecture and build a prototype with reduced power of the technology.

Interleaved current source inverters for high power PV converters prototyping

Département des Technologies Solaires (LITEN)

01-09-2018

SL-DRT-19-0061

jeremy.martin@cea.fr

Conventionally, systems for converting electrical energy in the photovoltaic domain are voltage inverter type structures [4] - [7]. In this case, the conversion chain of the photovoltaic energy is composed of two stages: a DC-DC converter followed by a voltage inverter (VSI). These voltage source topologies have short-term disadvantages (link capacitor lifetime problems) [5], [8], [9] and relatively low efficiency (due to a double conversion) [5]. As an alternative solution, the current inverter (CSI) structure can be used. Among the advantages of the CSI structure, can be listed: -A reduction in the number of power components, due to the conversion of energy with a single conversion stage [5] -A longer converter lifetime (compared to conventional structures) due to the suppression of the link capacitor [5], [8], [9] and a voltage in the blocked state seen by the switches lower [11] -Integration of natural short-circuit protection On the other hand, the CSI topology has the following disadvantages: -Relatively high conduction losses due to the series connection of devices (MOSFET + Diode) [4], [6] -Special protection requirements for AC and DC sides [4] For the CSI topology, one possible way to overcome the disadvantage of high switching losses is to use Wide bandgap devices (WBGs). Specifically, SiC semiconductors, because of their higher voltage ranges. The LSPV is currently working on: -The characterization of WBG semiconductors in 1.7kV blocking voltage -The design and building of a 100 kW CSI (using custom modules) -The characterization of the efficiency of the converters by calorimetric methods -The study and building of a high power multi-level CSI converter The subject of the thesis is the logical continuity of this work with an important part relative to the control of the structure, the interleaving of the blocks, the reduction of the size of the input inductor. [1] Jäger-Waldau, A. (2016). PV Status Report 2016. JRC Science for Policy Report (Publications Office of the European Union, 2016). [2] Photovoltaics report. Fraunhofer Institute for Solar Energy Systems-ISE, Freiburg, November 2016. Retieved May 2017. [3] BURGER, Bruno. Power Electronics for Photovoltaics. 2015. [4] Sahan, B., Araujo, S. V., Noding, C., & Zacharias, P. (2011). Comparative evaluation of three-phase current source inverters for grid interfacing of distributed and renewable energy systems. IEEE Transactions on Power Electronics, 26(8), 2304-2318. [5] Bülo, T., Sahan, B., Nöding, C., & Zacharias, P. (2007, September). Comparison of three-phase inverter topologies for grid-connected photovoltaic systems. In Proc. 22nd Eur. Photovolt. Sol. Energy Conf. Exhib., Milan, Italy. [6] Martin, J., Bier, A., Catellani, S., Alves-Rodrigues, L. G., & Barruel, F. (2016, May). A high efficiency 5.3 kW Current Source Inverter (CSI) prototype using 1.2 kV Silicon Carbide (SiC) bi-directional voltage switches in hard switching. In PCIM Europe 2016; Proceedings of (pp. 1-8). VDE. [7] Sahan, B., Vergara, A. N., Henze, N., Engler, A., & Zacharias, P. (2008). A single-stage PV module integrated converter based on a low-power current-source inverter. IEEE Transactions on Industrial Electronics, 55(7), 2602-2609. [8] Wang, H., Liserre, M., & Blaabjerg, F. (2013). Toward reliable power electronics: Challenges, design tools, and opportunities. IEEE Industrial Electronics Magazine, 7(2), 17-26. [9] Yang, S., Bryant, A., Mawby, P., Xiang, D., Ran, L., & Tavner, P. (2011). An industry-based survey of reliability in power electronic converters. IEEE Transactions on Industry Applications, 47(3), 1441-1451. [10] Engler, A., et al. "Design of a 200W 3-phase module integrated PV inverter as part of the European project PV-MIPS." Proceedings of the 21st European Photovoltaic Solar Energy Conference and Exhibition, Dresden, Germany. 2006. [11] Felgemacher, C., Araujo, S. V., Noeding, C., & Zacharias, P. (2016, May). Benefits of increased cosmic radiation robustness of SiC semiconductors in large power-converters. In PCIM Europe 2016; Proceedings of (pp. 1-8). VDE. [12] Rashid, M. H. (2010). Power electronics handbook: devices, circuits and applications. Academic press.

Extended Language for Real Time Systems Monitoring

Département Ingénierie Logiciels et Systèmes (LIST)

Laboratoire d'Ingénierie dirigée par les modèles pour les Systèmes Embarqués

01-04-2019

SL-DRT-19-0248

nicolas.rapin@cea.fr

The Phd Thesis is related to the ARTiMon monitoring tool developed in our Laboratory. The actual version of ARTiMon accepts a temporized linear time temporal logic for the specification of system requirements. The goal of the thesis is to study and implement language extensions and particularly we would like to specify probabilistic properties and have probabilistic verdicts. Other extensions could be explored, like fuzzy logic, regular expressions, automata, and analysis in the frequential domain in order to obtain a rather universal specification language.

Inverse reinforcement learning of a task performed by a human

DPLOIRE (CTReg)

Autre

01-01-2019

SL-DRT-19-0262

laurent.dolle@cea.fr

Learning from demonstration involves an agent (e.g., a robot) learning a task by watching another agent (e.g., a human) performing the same task. It often uses reinforcement-learning methods to improve the robot's ability to perform a task in new situations (i.e., generalization). These methods involve providing a positive reinforcement (i.e., a reward) when the outputs of the algorithms help achieving the task, but require a human designed reward function. The more the task is complex the more difficult is the reward function to design, but it can be learned from a series of examples with methods called inverse reinforcement learning. The use, jointly or not, of these techniques has shown encouraging results, but which are limited to toy examples and cannot be adapted as such to tasks more representative of the industrial environment. During the thesis, the PhD student will analyze and test state-of-the-art previous works. S/He will then propose a method, combining inverse reinforcement learning to other algorithms (e.g., generative adversarial networks, GAN), so that the robot will understand the task performed by the operator (with as little explanation from the operator as possible), and will generalize enough to make the robot robust to dynamic environments (obstacles, moving objects?). This method should be suited for a "pick and place" task in an industrial environment and ensure a reasonable enough learning period (information a priori, feedback from the operator) for tasks of medium complexity.

3D Objects discovery in 3D scene

DPLOIRE (CTReg)

Autre

01-01-2019

SL-DRT-19-0269

anthony.mouraud@cea.fr

Object detection and localization in images is a problem studied since many years. The latest technological developments now allow the real-time acquisition of depth data coupled to color data (RGBD). At the same time, modern machine computing capabilities and intelligent image processing methods have led to significant advances in the detection / localization of 2D objects with many different approaches (bounding boxes, contours, from CAD models ...). An important step is being taken in recent years with the research conducted to directly extract the volume of detected objects and their position in 3D. These works are still in their infancy, but the first results are encouraging, both from 2D images (eg DeepManta) and from 3D images (eg Deep Sliding Shapes). However, there remain several identifiable scientific / technological barriers before allowing the democratization of this type of approach for the automatic extraction of objects in potentially unknown scenes. The objective of this work is to identify the current approaches of detection / localization of 3D objects, to target their weaknesses and work on new processing technologies to mitigate them. Moreover, the object discovery in unknown environments and the inference of the operator's intention by observation / location of his attention are two areas of interest that this work aims at addressing. Beyond their applications for demonstration learning, the software bricks resulting from this project can also be reused for other applications such as augmented reality ("smart" scanning, etc.), surveillance or mobile mobility for example.

Integrated vector network analyzer for biomedical sensing applications

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-09-2019

SL-DRT-19-0290

baudouin.martineau@cea.fr

This thesis addresses the topic of highly integrated vector network analyzer (VNA) in the context of biomedical sensing applications. The thesis study will cover the architecture, the design and the measurement of such a VNA. This PhD research will give the opportunity to work in cross-scientific disciplinary from the microelectronic design to the understanding of biological material characteristics. To achieve this objective several milestone will have to be successfully completed. The awaited innovation will encompass several aspect: high precision local oscillator, high sensitivity, low cost CMOS process. The thesis will take place in the CEA Leti institute under the supervision of Dr Martineau and Dr Gonzalez (HDR). The publication in journals and international conferences will be encouraged and facilitated.

Study and design of an integrated system for the automatic calibration of dispersions within a transducers array and application to a PMUT array

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

01-09-2019

SL-DRT-19-0293

gwenael.bechet@cea.fr

The purpose of this thesis is to study and design an integrated electronic system dedicated to the automatic and continuous compensation of dispersions within a MEMS (Microelectromechanical Systems) array. With the dissemination and the continual expansion of Internet of Things (IoT) and Cyber-Physical Systems (CPS), man-machine and machine-machine interfaces require increasingly efficient and sophisticated sensors. In addition to advantages in cost, reliability, size and power consumption, MEMS based transducers enable sensors to integrate more and more intelligence in their front-end electronics. They also allow innovative topological configurations giving access to measurement ranges that are not addressable by their discrete counterparts. Arrays of MEMS based transducers enable the spatial discretization of the transduction surfaces and improve the measurements yields and accuracies (gas detector, mass spectrometry, pressure distribution, etc.). They also enable the resolution improvement of electromagnetic and acoustic beams (location, navigation, communication, etc.). Despite the considerable technological advancements that MEMS are continually enjoying, some application requirements are beyond the transducers intrinsic performances. It is then necessary to implement calibration systems to correct the transducers biases introduced during manufacture or evolving with the operating conditions. The evaluation and compensation of these errors requires costly calibration process in a dedicated test laboratory, that are not compatible with massive production. The aim of this thesis is to achieve an integrated electronic diagnostic alternative, an electromechanical BIST (Built-In Self-Test) specific to transducers arrays, combined with an automatic correction system, which will operate in coexistence with the main functions of the sensor interface. The proposed use-case is that of PMUT (Piezoelectric Micromachined Ultrasonic Transducer) arrays. These devices offer alternatives and complementary solutions to electromagnetic sensors for detection and localization [1], gesture recognition [2] or wake-up signals detection [3]. For most applications, these resonant transducers operate in transmit / receive modes (TX / RX) and need to be actuate at their resonance frequency to optimize the transmission power. The emitted and received beam is focused and steered by phase control. Errors and dispersion in the PMUT characteristics generates biases in their resonant frequency, gain and quality factor, leading to losses and distortions in the emitted and received beams. For example, a few percent of dispersions on the mechanical stiffness of the transducers can lead to several tens of percent loss on the acoustic power transmitted to a target. As a first step, the doctoral student will get familiar with the quantities and physical phenomena characterizing PMUT arrays. Based on an analytical model developed within the host laboratory, he will be able to understand the sensitivities to dispersions and their impact on the beam power and directivity. He will then define the electronic methods and architectures that will allow the system to converge towards the optimal operating conditions, for example by identifying the average resonance frequency of the array the required phase and gain correction coefficients to allocate to each transducer. The architecture and implementation choices must allow the system to adapt itself according to dispersions and drifts in a continuous and autonomous way, without disrupting the main measurement functions. The chosen solution will be implemented and validated in a mixed design environment in order to result in a functional demonstrator. [1] Przybyla, R. J., Tang, H. -., Guedes, A., Shelton, S. E., Horsley, D. A., & Boser, B. E. (2015). 3D ultrasonic rangefinder on a chip. IEEE Journal of Solid-State Circuits, 50(1), 320-334. [2] Ling, K., Dai, H., Liu, Y., & Liu, A. X. (2018). Ultragesture: Fine-grained gesture sensing and recognition. Paper presented at the 2018 15th Annual IEEE International Conference on Sensing, Communication, and Networking, SECON 2018, 1-9. [3] Yadav, K., Kymissis, I., & Kinget, P. R. (2013). A 4.4-µ W wake-up receiver using ultrasound data. IEEE Journal of Solid-State Circuits, 48(3), 649-660.

Architectures to Ensure the Functional Safety of Neural Network based Systems

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Silicium des Architectures Numériques

01-09-2019

SL-DRT-19-0296

adrian.evans@cea.fr

Neural networks are increasingly used in mission critical systems such as those used for image recognition in autonomous vehicles. These systems must comply with standards for functional safety, therefore it is essential to ensure they operate correctly in the presence of certain types of faults and that they can detect those faults which could result in dangerous situations. The same formal neural network can be implemented on different hardware platforms (CPUs, FPGAs, etc.), depending on the required performance. In some cases, implementations based on spike coding and neurons can result in significant power savings. It is well understood how to analyze and improve the reliability of classical digital circuits (micro-controllers, RAMs, etc.), however, these approaches are not directly applicable to neural networks, especially those using spike coding and analog neurons. The goal of this PhD thesis is to develop new approaches to improve the fault tolerance of spiking neural networks. As the first part of the thesis, new fault models and quantitative metrics to measure the correct operation of the system will be developed. Test cases using both classic coding and spiking networks will be prepared, to provide a reference for the studies. These will include cases using both off-line learning and unsupervised learning. Then the candidate will look for new techniques for detecting and managing faults in order to make the full system more robust. One avenue will be techniques for testing the system while it is operational (on-line test). Another research direction consists of studying how the architecture of the formal network and training data can be adapted to improve fault tolerance.

Nonlinear compressive imaging for machine learning

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Circuits Intégrés, Intelligents pour l'Image

01-10-2019

SL-DRT-19-0299

william.guicquero@cea.fr

In a context where the deployment of image sensors combined with computer vision tend to grow very quickly, the major challenges lie in information and signal processing. In the field of smart low-power sensors, the emerging breakthrough technology named Compressive Sensing is of major interest. In the case of embedded systems, autonomous decision-making becomes one of the core device feature while available resources (i.e., memory load, computing complexity and power consumption) remain highly limited. Indeed, the power consumption due to the sensor with dedicated signal processing is largely related to the overall data bandwidth and involved signal dimensionality. In particular, recent theoretical results demonstrate that standard Machine Learning approach can be advantageously applied in the compressed signal domain. However, those results are only restricted to the methods said as « linear », i.e. based on linear projections. The first objective of this PhD will thus be to properly identify theoretical limitations related to the combination of advanced Machine Learning with Compressive Sensing. It will aim at providing cutting-edge algorithm principles outperforming state-of-the-art tradeoffs between resources and inference accuracy. Thanks to a solid background in the laboratory on these fields of research, the goal of this thesis will be to evaluate the interest of introducing non-linearity during the acquisition process in order to improve the overall efficiency. This will help to define proper levers for smart sensor design enabling close-to-sensor context recognition (e.g., specific object detection with a highly limited hardware).

SPAD Imager for HDR ToF using multimodal data fusion

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Circuits Intégrés, Intelligents pour l'Image

01-10-2019

SL-DRT-19-0301

william.guicquero@cea.fr

Depth sensors are currently a very high trending topic. Indeed, in the fields of autonomous vehicles, portable electronic devices and the Internet of Things, new technology enablers now tend to provide handy 3D image data for future innovative end-user applications. There is a great diversity of 3D sensor types, either using passive imaging (depth from defocus, stereovision, phase pixels...) or using active imaging (ultrasounds, structured light, Time-of-Flight...). Each of these systems addresses specifications in terms of depth dynamic range (accuracy of the measurement versus maximum distance). In this thesis, we will study the specific case of Single Photon Avalanche Diodes (SPAD). Recent scientific results regarding this electro-photonic component demonstrate its relevance in the context of Time-of-Flight (ToF) imaging, especially in the case of integration in a 3D-stacked design flow exhibiting a pixel pitch of the order of ten micrometers. However, the nature of the data gathered by this type of component requires significant signal processing within the sensor to extract relevant information. This thesis will aim to revise traditional approaches related to histogram processing by directly extracting statistical features from raw data. Depending on the background and skills of the PhD candidate, two research axes would be investigated. First, on the hardware side, possible modifications of SPAD based sensor architecture in order to provide ?augmented? multi-modal information. Second, on the theoretical and algorithmic side, data fusion methods to improve the final reconstruction rendering of depth maps from sensed data.

DC-DC Power Converter at micro-Watt and millimeter scales

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

01-09-2019

SL-DRT-19-0314

antoni.quelel@cea.fr

The aim of the PhD is to develop compact (mm3) power supplies with high efficiency at low power delivery (nW to µW).

Study of 300-GHz electronically reconfigurable transmitarray antennas in monolithic technology

Département Systèmes

Laboratoire Antennes, Propagation, Couplage Inductif

01-12-2018

SL-DRT-19-0320

antonio.clemente@cea.fr

Due to the scarcity of electromagnetic spectrum resources and the need of broad bandwidth for high data-rate communications, the millimetre wave (mm-wave) and sub-THz bands from 30 to 350 GHz are very attractive for 5G and beyond 5G applications. In this context, high gain electronically reconfigurable antennas with beam-steering, multi-beam, and beam-forming capability are required in a huge number of emerging applications for radar, sensing, and communication systems (civil and military) typically ranging from C-band (4-8 GHz) to W-band (75-110 GHz). Typically composed of one or more radiant surfaces operating in transmission mode and illuminated by one or more focal sources, transmitarrays (also called discrete lens) are a recent cutting-edge antenna concept. Transmitarrays are realized using multilayer printed circuit technologies compatible with the integration of the active devices (diodes, MEMS, NEMS, semi-conductors, etc.). These devices can be used to control the electromagnetic field on the array aperture with excellent performances (bandwidth, cross-polarization level). CEA and IETR (university of Rennes I) have a very strong and unique expertise on transmitarray antennas. The previous realized studies form 2006 demonstrated the potentiality of transmitarrays in X-band (8-12 GHz), in Ka-band (28-40 GHz), and in V-band (50-70 GHz). The major scientific & technical innovations beyond the state-of-the-art are the following: first experimental demonstrations ? at world level ? (1) of highly efficient (70%) and highly directive (gain > 43 dBi) flat antennas at 300 GHz, (2) of ultra-flat transmitarray antennas, and (3) of self-alignment techniques for highly-directive flat antennas beyond 80 GHz.

Low Level Programming model for not "Von Neumann" architecture

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Infrastructure et Ateliers Logiciels pour Puces

01-10-2019

SL-DRT-19-0325

Henri-Pierre.Charles@cea.fr

Since the 60s the programming model used by processors is the "Von Neumann" model in which a processor will look for instructions and data to be processed in the same memory. Increasing the transistor density on a chip has increased its frequency but has produced a "bottleneck" to the memory that can not provide instructions and data at the same frequency : the memory wall. Many architectural solutions have been proposed to solve this bottleneck. One of the solutions we are studying is an architecture in which calculations are made in memory, without moving the data to the processor. The evaluation of this solution has shown impressive potential gains in speed (x10000) and energy (x30). To exploit this potential, it is necessary to change the programming model because the instructions will no longer be read in memory but generated by a processor that will drive one or more memory plane. The subject of the thesis will be the compilation of a high-level language to a flow of instructions interleaving processor instructions responsible for controlling and calculating addresses and instructions for controlling calculations in memory. This subject is a part of a bigger project in which we create a system composed of processor and computing memory.

Adaptive CMOS Image Sensor for smart vision systems

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Circuits Intégrés, Intelligents pour l'Image

01-10-2019

SL-DRT-19-0335

william.guicquero@cea.fr

The aim of this thesis is to explore new kind of smart vision sensor architectures using for enhance the sensor reactivity and for simplify the image processing. The studied vision system will use new 3D microelectronic technologies from CEA-leti. These technologies are capable to stack several integrated circuits. The main advantage is to propose a high density of interconnections between them, allowing connection at the pixel level. This characteristic allows us to think about a totally new architecture of the image processing chain of a basic imager (readout, amplification, compensation, colorization, tone mapping) in order to improve the agility, a better image quality, a better energy efficiency, with a low silicon footprint. The PhD student will benefit during his 3-years thesis of the expertise and the scientific excellence of the CEA leti to attend objectives with a high level of innovation through international patents and publications. The dynamic and autonomous candidate, will have a microelectronic master degree, specialized in analog integrated circuit design. A good knowledge of circuit design CAD tools will be important (Cadence, and also Matlab) and good knowledge in image processing will be appreciated. This thesis will start with the state of the art study, then the PhD student will define the optimal architecture. Finally, a test chip will be designed and tested. It will demonstrate the scientific and industrial potentialities of the proposed solutions.

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