Automatic generation of dynamic code generators from legacy code
Context
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Our laboratory is developing a technology for dynamic code generation around a tool called deGoal. deGoal is a tool designed to build specialized code generators (also known as compilettes) customized for each computing kernel we want to accelerate in an application. Such compilettes are designed with the aim to perform data- and architecture-dependent code optimizations and code generation at runtime. Furthermore, compilettes provide very fast code generation and low memory footprint. This approach is fundamentally different from the standard approach for dynamic compilation as used for example in Java Virtual Machines.
In order to target computing architectures that include domain-specific accelerators and to raise the level of abstraction of the source code of compilettes, deGoal uses a dedicated language. This language provides the best performance we can achieve from our technology, and has demonstrated its ability to achieve good performance improvements compared to highly optimised static code. However, the drawback is that one needs to rewrite the source code of a computing kernel from scratch in order to build a new compilette.
Goal
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The goal of this PostDoc is to implement an automatic generator of compilettes able to work from existing source code (typically: ANSI C), and able to be integrated in an industry-grade code generation toolchain.
Design of a new generation of MEMS flow or viscosity sensors
This Post-doc is defined to answer to various industrial requests for flow sensors and viscosity sensors working on a large range, low cost and able to measure different kind of fluids (liquid or gas).
The objective of this post-doc is to consider the design of a new generation of MEMS sensor for measuring flow or viscosity of any fluid that meets the specifications provided by the industry.
In particular, the possibilities of using a 3-axis micro-force sensor developed in the laboratory will be explored by exploiting the drag force or the tangential stresses near the walls of the pipes. Different cases will have to be evaluated depending on the flow dynamics of the different fluids.
A modeling and sizing of the sensor will have to be developed to determine the interactions with the fluids and the characteristics of the forces in the different flow rates.
The candidate should possess strong knowledge on fluidic and microsystems.
Compressed Sensing for ultrasonic imaging: disruptive method development and prototyping
In non-destructive ultrasonic testing, multi-element sensors are used for the inspection of structures to ensure the safety of people and infrastructures. Currently, one of the driving factor of an ultrasonic method is the number of elements of the sensor, influencing the speed and efficiency of the inspection but also the cost and the volume of the equipment. This project aims at developing a prototype of a multi-element sensor with a limited number of elements compared to current state of the art equipment, without losing imaging resolution. To achieve this goal, Compressed Sensing (CS), a recent technique of signal processing allowing to go beyond the traditional sampling theorems and to reconstruct data from severely undersampled measurements, will be used. The ultrasonic inspection procedure will need to be entirely rethought to meet the CS requirements, specifically the sparsity of the measured data and the incoherence of the measurement process. The expected results is a significant reduction (of the order of 5) of the number of elements to conduct imaging, which would be a true revolution in NDT with direct applications in various industrials sectors.
The following laboratories, all located in Saclay (France) of the CEA (the French atomic commission), will participate to the project: the NDT department for its expertise in multi-element ultrasonic testing and Neurospin and Cosmostat for their expertises in the field of CS, mainly applied to medical RMI imaging and astrophysics, respectively. The collaboration between these three labs, each among the worldwide leading institutes in their respective fields, will ensure the creation of a new and disruptive family of sensors.
Study and evaluation of a micro resonator based thermal sensor for uncooled infrared imagery
The project aims at establishing the feasibility of a novel infrared microbolometer sensor exploiting the thermal sensitivity of a free oscillating micro-nano-mechanical system (M & NEMS), whose resonant frequency changes with the infrared flux it absorbs. This is a concept out who was the subject of three patents.
The project addresses the needs of high resolution uncooled infrared imaging sensors (spectral band ranging from 8µm to 12µm) which is presently in expansion but whose next generation of products is still waiting for a breakthrough to reduce the pixel size, a key factor to improve performance and reduce the cost.
The objective of this post doctoral study is to achieve a proof of concept of this new architecture. In this outlook, the study will cover first the sizing of the device, then its design, implementation and validation at a single pixel level.
Distributed multiagent resources allocation. Application to district heating
Heating district networks in France fed more than one million homes and deliver a quantity of heat equal to about 5% of the heat consumed by the residential and tertiary sector. Therefore, they represent a significant potential for the massive introduction of renewable and recovery energy. However, heating networks are complex systems that must manage large numbers of consumers and producers of energy, and that are distributed in extended and highly branched geographical zones. The aim of the SIGMA project, realized in collaboration among the CEA-LIST and the CEA-LITEN, is to implement an optimal and dynamic management of heating networks. We propose a multidisciplinary approach, by integrating the advanced network management using Multi-Agent Systems (MAS), by taking into account spatial constraints using Geographic Information Systems (GIS) and by considering simplified physical models of transport and recovery of heat.
The post-doc’s goal is to design mechanisms for dynamically allocating resources that consider the geographical information from the GIS and the predictions of consumption, production and losses calculated with the physical models. In this way, several characteristics of the network will be considered: the continuous and dynamic aspect of the resource; sources with different behaviors, capabilities and production costs; the dependence of consumption / production to external aspects (weather, energy price); the internal characteristics of the network (losses, storage capacity). The coupling with a GIS should allow implementing self-configuration mechanisms for the management of different networks and different levels of granularity obtained by reduction of the original GIS. The MAS should dynamically establish the link between the suitable simplified models and the desired level of granularity and then it will create the agents needed to represent the system.
Development of innovative metal contacts for 2D-material field-effect-transistors
Further scaling of Si-based devices below 10nm gate length is becoming challenging due to the control of thin channel thickness. For gate length smaller than 10nm, sub-5nm thick Si channel is required. However, the process-induced Si consumption and the reduction of carrier mobility in ultrathin Si layer can limit the channel thickness scaling. Today, the main contenders that allow the extension of the roadmap to ultra-scaled devices are 2D materials, particularly the semiconducting transition metal dichalcogenides (TMD). Due to their unique atomically layered structure, they offer improved immunity to short-channel-effects in comparison to usual Si-based field-effect-transistors (FETs). This makes them very attractive for the application of more-Moore electronics.
However, the scalability of MOSFET device and the introduction of new material make source and drain contact a major issue. If many efforts have been made, in the past years, to reduce Fermi level pinning and Schottky barrier height, for many, these approaches are not industrially scalable. The main objective of this work is then to propose an in-depth understanding of electrical contact characteristics (based on different material) to identify the lowest contact resistance. The processes involved, offering an optimal contact resistance, must be compatible with wafer-scale processing for an integration in our 200/300mm advanced CMOS platform. The post-doc will in-depth study mechanisms enabling the formation of small contact resistances (between MoS2 and metal). It will have to identify the most promising contact material and to develop the associated deposition processes (ALD/PVD). Finally, electrical characterization of contact will be performed to qualify both material and interfaces enabling optimal operation of future 2D FETs
Selective removal of metal alloy for advanced silicidation applied to sub-20nm CMOS transistors
CMOS transistor performances depend on electrical contact resistivity reduction. Thus, self aligned silicidation (salicide) is one of the key processes which have to be improved to meet the ITRS requirements for the future technological nodes. Nowadays, solid state reaction between thin metal layer (Ni1-yPty < 10nm) and a silicon substrate allows to decrease access resistances of transistor source & drain. The metal is currently deposited by physical vapor deposition method all over the wafer surface. Under heat treatment, metal reacts preferably with semiconductor areas rather than dielectrics ones. Then, unreacted metal layer is selectively etched with an appropriate acidic solution; only metal silicide remains.As new specifications (use of ultra-thin Ni-alloy,very low temperature process leading to partial salicidation, use of various additive metals ...)are required for advanced nodes (C20nm & C14nm), the capability to chemically remove the excess of metal on dielectric areas has to be investigated. In the clean room environment of CEA-LETI (Grenoble, France), the candidate will work on innovative wet chemistries to remove selectively the different metallic layers (Ni, Pd, NiCo, NiPd…). In a first time preliminary test will be conducted on sample in manual tank in order to check removal kinetic and global selectivity on structures devices… Based on several characterization techniques (TXRF, XRR, AFM, SEM, TEM, XRD…), residual additive interaction with dielectric and chemical mixture behavior towards the metal rich phase on silicided area (roughness, resistivity) will be studied. Different semi-conductor (Si, SiGe…) and dielectrics surfaces (SiO2, SixNy…) will be investigated. Afterwards the most promising selective processes will be selected to be installed on a fully automatic 300mm tool. Finally, best processes will be integrated on critical patterned wafer architectures for morphological and electrical characterizations.
Design of integrated photonics modules
Design of next generation optoelectronic transceivers (particularly on-board modules) requires the merging of two advanced technologies: Silicon Photonics and 3D Silicon Packaging, both being developed at Leti.
In order to meet the requirements in term of technical specifications, cost and density, it is needed to achieve a codesign involving mechanical, thermal, optical and mainly RF aspects.
The aim of the work consists in designing such integrated modules by optimizing the RF interconnections of the module (internal and external), and the proper setup of the integrated circuits (ASICs). Modelling of several architectures will be led under HFSS and ADS softwares.
Finally, the integration of the module into its system environnement will be taken in charge, so as its characterization (involving testboard and testbench design).
Real time low cost algorithms for brain computer interface with multiple degrees of freedom
The topic of the postdoctoral project is the optimization of BCI methods and algorithms for medical application in humans (quadriplegic subjects).
Namely the particular goal of the postdoctoral fellow will be optimization and the acceleration of calculation to allow multiple degrees of freedom (up to 26) in real time. Selecting the appropriate features subset will improve the computational efficiency and the quality of control. To this purpose the algorithms of sparse modeling will be applied.
To map ECoG recordings to the spatial-temporal-frequency space, continuous wavelet transform (CWT) is applied. Optimization will include the implementation of low cost CWT and C++ coding.
The project will include the test and the adaptation of BCI algorithms to wireless signal transmission with the implant WIMAGINE.
Finally the adaptation of algorithms to medical environment of quadriplegic subjects (the use of imaginary tasks, presence of stimuli in the signal, the restricted duration of experiments) will be under responsibility of postdoctoral scientist.
Development of a Metal Supported Cell for Hydrogen production by High Temperature Steam Electrolysis
The development of Metal Supported Cells (MSC) for High Temperature Steam Electrolysis (HTSE) constitutes an interesting innovation able to reduce the degradation of this component under operation. An increase in the cell life time would be a valuable contribution to cost reduction and is able at positioning HTSE as an alternative process to other hydrogen production technologies. However, some progresses in the elaboration of MSCs are still required. Within the current process, functional ceramic layers of the MSC are joined to the metallic substrate at elevated temperature (> 1000 °C). Mismatch of the mechanical properties of the materials as well as the reducing conditions fixed by the metal substrate during sintering lead to MSCs having insufficient electrochemical performances. The post-doctorate aims, on the one hand, at obtaining a better understanding of the mechanisms that occur in the multilayer structure during sintering and, on the other hand, at proposing and testing technological solutions able to improve to reliability of MSC elaboration.