Asynchronous 3D (Async3D): Design Methodology and Analysis of 3D Asynchronous Circuits

This dissertation focuses on the application of 3D integrated circuit (IC) technology on asynchronous logic paradigms, mainly NULL Convention Logic (NCL) and Multi-Threshold NCL (MTNCL). It presents the Async3D tool flow and library for NCL and MTNCL 3D ICs. It also analyzes NCL and MTNCL circuits in 3D IC. Several FIR filter designs were implement in NCL, MTNCL, and synchronous architecture to compare synchronous and asynchronous circuits in 2D and 3D ICs. The designs were normalized based on performance and several metrics were measured for comparison. Area, interconnect length, power consumption, and power density were compared among NCL, MTNCL, and synchronous designs. The NCL and MTNCL designs showed improvements in all metrics when moving from 2D to 3D. The 3D NCL and MTNCL designs also showed a balanced power distribution in post-layout analysis. This could alleviate the hotspot problem prevalently found in most 3D ICs. NCL and MTNCL have the potential to synergize well with 3D IC technology

Synthesis and characterization of a metal-salen base pair for the assembly of programmed metal arrays inside the DNA double helix

Base pairing in natural oligonucleotides relies on hydrogen bonding and pi-stacking. Applying coordinative interactions between ligand-like nucleobases and metal cations is a new way of assembling artificial oligonucleotide duplexes. The incorporation of numerous metal-base pairs into oligonucleotides may lead to interesting compounds for nano-technological applications. In this thesis, the synthesis of the salen-metal base pair is described, which comprises preparation of a suitable protected salicylic aldehyde precursor and an organo-cuprate mediated C-glycosidation as the key step. An x-ray structure of the monomeric copper-salen base pair shows a very good geometrical match with natural Watson-Crick base pairs. Up to 10 consecutive salicylic aldehyde-nucleobases could be incorporated into DNA oligonucleotides by means of phosphoramidite chemistry. The synthesized double strands with one ligand show typical B-DNA CD-spectra and distinct melting characteristics. Addition of excess ethylenediamine and 1 eq of Mn2+ or Cu2+ increase the melting temp. by 28 °C and 42 °C, respectively. The complexation of these and other metals was examined by UV-, CD- and EPR-spectroscopy and high res. ESI mass spectrometry. It was possible to stack 10 manganese atoms inside the double helix and to prepare sequence specifically arrays of up to 5 copper ions plus 5 mercury ions inside one duplex

Biogeochemical activity and associated biodiversity at reduced deep-sea hotspot ecosystems

Understanding biodiversity and its patterns across space, time and environmental gradients is central in order to assess the functioning of natural systems and their resilience to external perturbations. To date, the deep-sea floor and its associated ecosystems remain one of least explored environments on Earth, hence, little is known about their biodiversity, and especially that of microbes. Here we investigated the biogeochemical activity and associated bacterial biodiversity of two hotspot ecosystems in the deep-sea, the cold seeps and wood falls. Cold seeps and wood falls are peculiar ecosystems at the deep-sea floor, at which unique sources of energy such as methane and wood-derived cellulose fuel high biomasses of faunal communities with special diversity, typically not encountered at the deep-sea floor. In this study we specifically focused on the investigation of microbial communities since on one hand their diversity patterns are the least understood, and also because their capabilities to utilize methane and cellulose are crucial for the supply of energy to these ecosystems. Cold seeps and wood falls are isolated and fractured ecosystems with only small areal coverage, which poses a challenge for the dispersal of their associated communities and maintenance of their populations. The interconnectivity of these isolated ecosystems and the biodiversity patterns of microbes across different spatial scales are largely unknown. The combination of molecular fingerprinting and geochemical approaches used in this study helped to understand how microbial communities of seep and wood falls are connected over different spatial scales and identify the main environmental factors shaping their diversity. In Chapter I the local-scale patterns of bacterial community structure and their relation to the sediment heterogeneity was investigated at the REGAB cold seep pockmark. Strong variations in the sediment geochemistry and the core biogeochemical processes were detected between different reduced habitats, which were related to differences in the methane effluxes that ranged over two orders of magnitude. Variation in the structure of bacterial communities was linked to local sediment heterogeneity. Methane, the main energy source at cold seeps, was identified as the most important factor that shaped the seep bacterial community structure and distributions of chemosynthetic megafauna. The link between the relative abundance of symbiotic bacteria in the gills of a cold seep chemosynthetic mussel and their energy sources was investigated in Chapter II. Mussels inhabiting gassy sediments laden with methane had relatively higher abundance of methanotrophic symbionts that take up methane, in comparison to thiotrophic symbionts that rely on sulfide as their source of energy. In addition, the abundances of methanotrophs seemed to be linked to variations in methane concentrations in the bottom water, and were correlated with the content of methane-derived carbon in the mussel biomass. The results presented in Chapter III reveal how seep bacterial communities vary on local and regional scales, within and between cold seep sites. Variation in the seep bacterial community was not correlated to geographic distance, and instead communities displayed patchy structure reflecting on the variability in the sulfide content, as their main energy source. Highest bacterial turnover, with > 50% replacement with new bacterial types was evident between reduced habitats, separated by few meters to hundreds of meters. This result suggest that small reduced habitats, not more than few meters in diameter, represent biodiversity hotspots and contribute substantially to the overall diversity of the deep-sea floor. In the last chapter (IV) the temporal and spatial variations of communities associated to wood falls were investigated using experimental wood deployments. The results of this study suggest that biogeography plays an important role for the composition of both bacteria and fauna of wood-associated communities. Temporal succession of bacterial and faunal communities occurred within a period of 1 to 2 y. During the whole immersion period the bacterial communities associated to the wood fall remained distinct from the surrounding background sediments, indicating that wood falls represent an important source of diversity in the deep-sea floor

FC³ - 1st Fuel Cell Conference Chemnitz 2019 - Saubere Antriebe. Effizient Produziert.: Wissenschaftliche Beiträge und Präsentationen der ersten Brennstoffzellenkonferenz am 26. und 27. November 2019 in Chemnitz

Die erste Chemnitzer Brennstoffzellenkonferenz wurde vom Innovationscluster HZwo und dem Fraunhofer-Institut für Werkzeugmaschinen und Umformtechnik IWU durchgeführt. Ausgewählte Fachbeiträge und Präsentationen werden in Form eines Tagungsbandes veröffentlicht.The first fuel cell conference was initiated by the innovation cluster HZwo and the Fraunhofer Institute for Machine Tools and Forming Technology. Selected lectures and presentations are published in the conference proceedings

OSS architecture for mixed-criticality systems – a dual view from a software and system engineering perspective

Computer-based automation in industrial appliances led to a growing number of logically dependent, but physically separated embedded control units per appliance. Many of those components are safety-critical systems, and require adherence to safety standards, which is inconsonant with the relentless demand for features in those appliances. Features lead to a growing amount of control units per appliance, and to a increasing complexity of the overall software stack, being unfavourable for safety certifications. Modern CPUs provide means to revise traditional separation of concerns design primitives: the consolidation of systems, which yields new engineering challenges that concern the entire software and system stack. Multi-core CPUs favour economic consolidation of formerly separated systems with one efficient single hardware unit. Nonetheless, the system architecture must provide means to guarantee the freedom from interference between domains of different criticality. System consolidation demands for architectural and engineering strategies to fulfil requirements (e.g., real-time or certifiability criteria) in safety-critical environments. In parallel, there is an ongoing trend to substitute ordinary proprietary base platform software components by mature OSS variants for economic and engineering reasons. There are fundamental differences of processual properties in development processes of OSS and proprietary software. OSS in safety-critical systems requires development process assessment techniques to build an evidence-based fundament for certification efforts that is based upon empirical software engineering methods. In this thesis, I will approach from both sides: the software and system engineering perspective. In the first part of this thesis, I focus on the assessment of OSS components: I develop software engineering techniques that allow to quantify characteristics of distributed OSS development processes. I show that ex-post analyses of software development processes can be used to serve as a foundation for certification efforts, as it is required for safety-critical systems. In the second part of this thesis, I present a system architecture based on OSS components that allows for consolidation of mixed-criticality systems on a single platform. Therefore, I exploit virtualisation extensions of modern CPUs to strictly isolate domains of different criticality. The proposed architecture shall eradicate any remaining hypervisor activity in order to preserve real-time capabilities of the hardware by design, while guaranteeing strict isolation across domains.Computergestützte Automatisierung industrieller Systeme führt zu einer wachsenden Anzahl an logisch abhängigen, aber physisch voneinander getrennten Steuergeräten pro System. Viele der Einzelgeräte sind sicherheitskritische Systeme, welche die Einhaltung von Sicherheitsstandards erfordern, was durch die unermüdliche Nachfrage an Funktionalitäten erschwert wird. Diese führt zu einer wachsenden Gesamtzahl an Steuergeräten, einhergehend mit wachsender Komplexität des gesamten Softwarekorpus, wodurch Zertifizierungsvorhaben erschwert werden. Moderne Prozessoren stellen Mittel zur Verfügung, welche es ermöglichen, das traditionelle >Trennung von Belangen< Designprinzip zu erneuern: die Systemkonsolidierung. Sie stellt neue ingenieurstechnische Herausforderungen, die den gesamten Software und Systemstapel betreffen. Mehrkernprozessoren begünstigen die ökonomische und effiziente Konsolidierung vormals getrennter Systemen zu einer effizienten Hardwareeinheit. Geeignete Systemarchitekturen müssen jedoch die Rückwirkungsfreiheit zwischen Domänen unterschiedlicher Kritikalität sicherstellen. Die Konsolidierung erfordert architektonische, als auch ingenieurstechnische Strategien um die Anforderungen (etwa Echtzeit- oder Zertifizierbarkeitskriterien) in sicherheitskritischen Umgebungen erfüllen zu können. Zunehmend werden herkömmliche proprietär entwickelte Basisplattformkomponenten aus ökonomischen und technischen Gründen vermehrt durch ausgereifte OSS Alternativen ersetzt. Jedoch hindern fundamentale Unterschiede bei prozessualen Eigenschaften des Entwicklungsprozesses bei OSS den Einsatz in sicherheitskritischen Systemen. Dieser erfordert Techniken, welche es erlauben die Entwicklungsprozesse zu bewerten um ein evidenzbasiertes Fundament für Zertifizierungsvorhaben basierend auf empirischen Methoden des Software Engineerings zur Verfügung zu stellen. In dieser Arbeit nähere ich mich von beiden Seiten: der Softwaretechnik, und der Systemarchitektur. Im ersten Teil befasse ich mich mit der Beurteilung von OSS Komponenten: Ich entwickle Softwareanalysetechniken, welche es ermöglichen, prozessuale Charakteristika von verteilten OSS Entwicklungsvorhaben zu quantifizieren. Ich zeige, dass rückschauende Analysen des Entwicklungsprozess als Grundlage für Softwarezertifizierungsvorhaben genutzt werden können. Im zweiten Teil dieser Arbeit widme ich mich der Systemarchitektur. Ich stelle eine OSS-basierte Systemarchitektur vor, welche die Konsolidierung von Systemen gemischter Kritikalität auf einer alleinstehenden Plattform ermöglicht. Dazu nutze ich Virtualisierungserweiterungen moderner Prozessoren aus, um die Hardware in strikt voneinander isolierten Rechendomänen unterschiedlicher Kritikalität unterteilen zu können. Die vorgeschlagene Architektur soll jegliche Betriebsstörungen des Hypervisors beseitigen, um die Echtzeitfähigkeiten der Hardware bauartbedingt aufrecht zu erhalten, während strikte Isolierung zwischen Domänen stets sicher gestellt ist

Design and Test of a Gate Driver with Variable Drive and Self-Test Capability Implemented in a Silicon Carbide CMOS Process

Discrete silicon carbide (SiC) power devices have long demonstrated abilities that outpace those of standard silicon (Si) parts. The improved physical characteristics allow for faster switching, lower on-resistance, and temperature performance. The capabilities unleashed by these devices allow for higher efficiency switch-mode converters as well as the advance of power electronics into new high-temperature regimes previously unimaginable with silicon devices. While SiC power devices have reached a relative level of maturity, recent work has pushed the temperature boundaries of control electronics further with silicon carbide integrated circuits. The primary requirement to ensure rapid switching of power MOSFETs was a gate drive buffer capable of taking a control signal and driving the MOSFET gate with high current required. In this work, the first integrated SiC CMOS gate driver was developed in a 1.2 μm SiC CMOS process to drive a SiC power MOSFET. The driver was designed for close integration inside a power module and exposure to high temperatures. The drive strength of the gate driver was controllable to allow for managing power MOSFET switching speed and potential drain voltage overshoot. Output transistor layouts were optimized using custom Python software in conjunction with existing design tool resources. A wafer-level test system was developed to identify yield issues in the gate driver output transistors. This method allowed for qualitative and quantitative evaluation of transistor leakage while the system was under probe. Wafer-level testing and results are presented. The gate driver was tested under high temperature operation up to 530 degrees celsius. An integrated module was built and tested to illustrate the capability of the gate driver to control a power MOSFET under load. The adjustable drive strength feature was successfully demonstrated