Disertační práce se zabývá simulací elektronických obvodů. Popisuje metodu kapacitorové substituce (CSM) pro převod elektronických obvodů na elektrické obvody, jež mohou být následně řešeny pomocí numerických metod, zejména Moderní metodou Taylorovy řady (MTSM). Tato metoda se odlišuje automatickým výběrem řádu, půlením kroku v případě potřeby a rozsáhlou oblastí stability podle zvoleného řádu. V rámci disertační práce bylo autorem disertace vytvořeno specializované programové vybavení pro řešení obyčejných diferenciálních rovnic pomocí MTSM, s mnoha vylepšeními v algoritmech (v porovnání s TKSL/386). Tyto algoritmy zahrnují zjednodušování obecných výrazů na polynomy, paralelizaci nezávislou na integrační metodě atp. Tento software běží na linuxovém serveru, který komunikuje pomocí protokolu TCP/IP. Toto vybavení bylo úspěšně použito pro simulaci VLSI obvodů, jejichž řešení pomocí CSM bylo značně rychlejší a spotřebovávalo méně paměti než state-of-the-art SPICE.

Background: Breastfeeding confers health and social benefits on both mother and baby and is thus a key global public health priority, with exclusive breastfeeding for the first six months recommended. A variety of factors can influence a woman’s decision to initiate breastfeeding but a short duration of breastfeeding appears to be common in developed countries. In the UK, promotion of breastfeeding has been government policy since 1974 and gradually the incidence has increased. In Scotland in 2010 the incidence was 74% but by one week 17% of women had given up. A minority of women find that their babies attach easily at birth and more than half report problems at this time. The prevalence of exclusive breastfeeding falls sharply in the first few weeks and the introduction of formula is associated with a shorter duration. It is therefore crucial to understand what happens at this time to enable women to continue breastfeeding effectively. Study Aim: To use Social Cognitive Theory (SCT) to explore and help explain the expectations, knowledge and experiences of women and midwives with regard to breastfeeding initiation. Methods: A systematic review of qualitative studies synthesised using thematic analysis and SCT was conducted and afforded insight into what had been known before and highlighted further aspects that needed to be explored with a qualitative study. The qualitative study was comprised of five focus groups with ten antenatal women, eight postnatal women and eighteen midwives. Photographs included in a leaflet “Feeding cues at birth”, and the chart of “Feeding cues after the first few hours” were developed and used as focussing exercises during the focus groups and interviews. The focus groups and interviews were recorded, transcribed and analysed using a hybrid process of inductive and deductive thematic analysis which integrated data driven codes with theory driven codes based on SCT. Results: Twenty one studies were included in the systematic review and identified clear differences in the experiences of women when breastfeeding was going well as compared to when it was going wrong at the start. There were also differences in the midwives’ knowledge, experience and confidence when breastfeeding was going well in contrast to when it was going wrong. The synthesis did not identify any qualitative studies relevant to initiation which explored skin contact, instinctive behaviour or strategies to resolve failure to attach in the first few days after birth, from the perspectives of mothers and midwives. These topics were therefore explored in detail in the qualitative study. Few mothers recruited to my study experienced instinctive behaviour and successful attachment (in SCT enactive behaviour) at birth. The majority of mothers did not experience attachment at birth and struggled to persist and maintain their motivation to enable breastfeeding initiation in an unfamiliar environment. Midwives’ social expectations and environmental circumstances made women centred care difficult. Midwives considered that sleepy babies who were unable to feed were normal, but women were unprepared for this, compounding the difficulties in initiating breastfeeding. The triangulation of the findings from the systematic review and the qualitative study provide a more complete picture of contributory factors to understanding of difficulties in breastfeeding initiation. Conclusion: It is recognised that behaviour interacts with emotions, perceived abilities and the environment, as in triadic reciprocal causation, which affects peoples’ decisions, experiences and abilities to enable the successful initiation of breastfeeding. Social Cognitive Theory could be used as a framework to develop strategies and materials to enhance women’s confidence both antenatally and in the postnatal period. In a minority of women, breastfeeding goes well and is more likely when the baby is an active participant and the midwife a knowledgeable and confident supporter. This is not the case for the majority of women and babies or their midwives. There is a need to consider strategies to develop appropriate skills and environmental changes that would in turn lead to changes in behaviour and successful interventions. More emphasis should be made clinically on facilitating instinctive behaviour. The current position where babies’ sleepy behaviour is considered normal in this particular environment could be challenged. Social Cognitive Theory could be utilised in research to develop strategies to increase women’s and midwives’ confidence specifically in initiation.

La miniaturisation des circuits intégrés numériques tend à augmenter leur sensibilité aux radiations. Ainsi le rayonnement naturel peut induire des événements singuliers et porter atteinte à la fiabilité des circuits.Cette thèse porte sur la modélisation des mécanismes à l'origine de ces événements singuliers et sur le développement de solutions de durcissement par conception permettant de limiter l'impact des radiations sur le taux d'erreur.Dans une première partie, nous avons notamment développé une approche dénommée RWDD (Random-Walk Drift- Diffusion) modélisant le transport et la collection de charges au sein d'un circuit, sur la base d'équations physiques sans paramètre d'ajustement. Ce modèle particulaire et sa résolution numérique transitoire permettent de coupler le transport des charges avec un simulateur circuit, tenant ainsi compte de l'évolution temporelle des champs électriques dans la structure. Le modèle RWDD a été intégré avec succès dans une plateforme de simulation capable d'estimer la réponse d'un circuit suite à l'impact d'une particule ionisante.Dans une seconde partie, des solutions de durcissement permettant de limiter l'impact des radiations sur la fiabilité des circuits ont été développées. A l'échelle des cellules élémentaires, de nouvelles bascules robustes aux radiations ont été proposées, en limitant leur impact les performances. Au niveau système, une méthodologie de duplication de l'arbre d'horloge a été développée. Enfin, un flot de triplication a été conçu pour les systèmes dont la fiabilité est critique. L'ensemble de ces solutions a été implémenté en technologie 65 nm et UTBB-FDSOI 28 nm et leur efficacité vérifiée expérimentalement. / The extreme technology scaling of digital circuits leads to increase their sensitivity to ionizing radiation, whether in spatial or terrestrial environments. Natural radiation can now induce single event effects in deca-nanometer circuits and impact their reliability.This thesis focuses on the modeling of single event mechanisms and the development of hardening by design solutions that mitigate radiation threat on the circuit error rate.In a first part of this work, we have developed a physical model for both the transport and collection of radiation-induced charges in a biased circuit, derived from pure physics-based equations without any fitting parameter. This model is called Random-Walk Drift-Diffusion (RWDD). This particle-level model and its numerical transient solving allows the coupling of the charge collection process with a circuit simulator, taking into account the time variations of the electrical fields in the structure. The RWDD model is able to simulate the behavior of a circuit following a radiation impact, independently of the implemented function and the considered technology.In a second part of our work, hardening solutions that limit radiation impacts on circuit reliability have been developed. At elementary cell level, new radiation-hardened latch architectures have been proposed, with a limited impact on performances. At system level, a clock tree duplication methodology has been proposed, leaning on specific latches. Finally, a triplication flow has been design for critical applications. All these solutions have been implemented in 65 nm and UTBB-FDSOI 28nm technologies and radiation test have been performed to measure their hardening efficiency.

Ce travail traite de la fiabilité des composants électroniques de puissance comme les MOSFET et les IGBT affectés par l'Environnement Radiatif Naturel dans lequel ils évoluent. Cette problématique fait, de nos jours, partie intégrante de la fiabilité des composants. Alors qu'elle concernait initialement les composants destinés à travailler en environnement radiatif sévère du type spatial ou aéronautique, l'évolution et la complexité de l'électronique embarquée, qui peut interagir avec ce type d'environnement et avoir des effets potentiellement dommageables, nous amène à prendre en compte ces contraintes radiatives comme le cas d'ion lourd. C'est dans ce cadre que nous avons effectué les travaux présentés dans ce mémoire. Des simulations utilisant les outils Synopsys TCAD ont été menées afin de mieux comprendre les mécanismes de défaillances comme le Single Event Burn-out (SEB) et le Single Event Latch-up (SEL) ainsi que la définition de critères de déclenchement, de comportement et de la sensibilité de différents composants (VDMOS, SJ-MOSFET, IGBT planar et IGBT trench). Ces études nous ont permis de proposer et d'évaluer des solutions de durcissement au niveau de design permettant la désensibilisation contre les phénomènes de déclenchement liés aux structures parasites.

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CubeSat missions needs components that are tolerant against the radiation in space. The hardware components must be reliable, and it must not compromise the functionality on-board during the mission. At the same time, the cost of hardware and its development should not be high. Hence, this thesis discusses the design and development of a CubeSat architecture using a Commercial Off-The- Shelf (COTS) Multi-Processor System on Chip (MPSoC). The architecture employs an affordable Rad-Hard Micro-Controller Unit as a Supervisor for the MPSoC. Also, it uses several radiation mitigation techniques such as the Latch-up protection circuit to protect it against Single-Event Latch-ups (SELs), Readback scrubbing for Non- Volatile Memories (NVMs) such as NOR Flash and Configuration scrubbing for the FPGA present in the MPSoC to protect it against Single-Event Upset (SEU)s, reliable communication using Cyclic Redundancy Check (CRC) and Space packet protocol. Apart from such functionalities, the Supervisor executes tasks such as Watchdog that monitors the liveliness of the applications running in the MPSoC, data logging, performing Over-The-Air Software/Firmware update. The thesis work implements functionalities such as Communication, Readback memory scrubbing, Configuration scrubbing using SEM-IP, Watchdog, and Software/Firmware update. The execution times of the functionalities are presented for the application done in the Supervisor. As for the Configuration scrubbing that was implemented in Programmable Logic (PL)/FPGA, results of area and latency are reported. / CubeSat-uppdrag behöver komponenter som är toleranta mot strålningen i rymden. Maskinvarukomponenterna måste vara pålitliga och funktionaliteten ombord får inte äventyras under uppdraget. Samtidigt bör kostnaden för hårdvara och dess utveckling inte vara hög. Därför diskuterar denna avhandling design och utveckling av en CubeSatarkitektur med hjälp av COTS (eng. Custom-off-The-Shelf) MPSoC (eng. Multi Processor System-on-Chip). Arkitekturen använder en prisvärd strålningshärdad (eng. Rad-Hard) Micro-Controller Unit(MCU) som Övervakare för MPSoC:en och använder också flera tekniker för att begränsa strålningens effekter såsom kretser för att skydda kretsen från s.k. Single Event Latch-Ups (SELs), återläsningsskrubbning för icke-volatila minnen (eng. Non-Volatile Memories) NVMs som NOR Flash och skrubbning av konfigurationsminnet skrubbning för FPGA:er i MPSoC:en för att skydda dem mot Single-Event Upsets (SEUs), och tillhandahålla pålitlig kommunikation mha CRC och Space Packet Protocol. Bortsett från sådana funktioner utför Övervakaren uppgifter som Watchdog för att övervaka att applikationerna som körs i MPSoC:en fortfarande är vid liv, dataloggning, och Over- the-Air-uppdateringar av programvaran/Firmware. Examensarbetet implementerar funktioner såsom kommunikation, återläsningsskrubbning av minnet, konfigurationsminnesskrubbning mha SEM- IP, Watchdog och uppdatering av programvara/firmware. Exekveringstiderna för utförandet av funktionerna presenteras för den applikationen som körs i Övervakaren. När det gäller konfigurationsminnesskrubbningen som implementerats i den programmerbara logiken i FPGA:n, rapporteras area och latens.