Explosionsgeschützte Niederspannungs-Schaltgerätekombinationen, häufig auch als explosionsgeschützte Energieverteiler bezeichnet, werden eingesetzt, um in explosionsfähigen Atmosphären elektrische Energie sicher zu übertragen und zu verteilen. Um einen über Jahrzehnte sicheren Betrieb zu gewährleisten sind die Energieverteiler mindestens derart thermisch zu dimensionieren, dass normativ festgelegte Grenztemperaturen nicht überschritten werden. Explosionsgeschützte Energieverteiler unterscheiden sich von konventionellen Schaltgerätekombinationen. Wegen des Explosionsschutzes sind verschiedene Schalt- und Schutzgeräte zusätzlich in druckfeste Kapselungen eingebaut. Die Reihenmontage druckfest gekapselter Geräte erfolgt mit Abstand. Das Verdrahten der Geräte und Betriebsmittel erfolgt vielfach mit Leitungen mit wärmebeständiger Isolierung. Die Leitungen sind häufig in Bündeln gelegt. Die Verteilergehäuse besitzen keine Lüftungsöffnungen. Für den Explosionsschutz sind zusätzlich alle höchsten Oberflächentemperaturen maßgeblich, die mit zündfähiger Atmosphäre in Kontakt kommen können (Hotspots). Die Hotspot-Temperaturen dürfen normativ festgelegte Grenztemperaturen nicht überschreiten. Die Wärmenetzmethode ist ein etabliertes Verfahren, um die Erwärmung konventioneller Schaltgeräte und Schaltgerätekombinationen effizient zu berechnen. Die Erwärmung explosionsgeschützter Energieverteiler einschließlich der Hotspots konnte bisher nicht mit der Wärmenetzmethode berechnet werden. In dieser Arbeit werden die dominanten Wärmequellen und Wärmeübertragungsvorgänge anhand eines typischen explosionsgeschützten Energieverteilers experimentell sowie mit Hilfe numerischer Methoden (Finite-Elemente-Methode, Finite-Volumen-Methode) untersucht. Auf Grundlage der Untersuchungsergebnisse werden Berechnungsmodelle für die Erwärmung von Leitungsbündeln und für die Geschwindigkeit umlaufender Kühlmittelströme erarbeitet und in die Wärmenetzmethode implementiert. Um die Hotspot-Temperaturen auf druckfesten Kapselungen zu berechnen sind erstmals fein aufgelöste Wärmenetze erforderlich. Es wird ein Verfahren zum strukturierten Aufbau fein aufgelöster Wärmenetze erarbeitet. Ein einfacher Ansatz zum Berechnen der Erwärmung ebener Kontakte wird in dieser Arbeit auf gewölbte Schaltkontakte erweitert, indem die erforderliche scheinbare Kontaktfläche zwischen den Kontaktgliedern erstmals aus Messungen mit Druckmessfolien bestimmt wird. Für die Betriebsmittel des explosionsgeschützten Energieverteilers werden die Wärmenetze aufgebaut, parametriert und experimentell verifiziert. Das Gesamtwärmenetz der Musteranlage wird durch das Zusammenschalten der Wärmenetze der Betriebsmittel aufgebaut und experimentell verifiziert. Die mit dem verifizierten Gesamtwärmenetz berechneten Temperaturen werden mit gemessenen Temperaturen bei 100 % Bemessungsstrom verglichen. Die Berechnung zeigt eine hohe Übereinstimmung mit den gemessenen Temperaturen. Die höchsten noch verbleibenden Abweichungen zur gemessenen Übertemperatur betragen ΔΘ = +6,3 K und ΔΘ = -6,2 K. Die berechneten Orte der Heißpunkte stimmen mit der Messung überein. Die berechneten Heißpunkttemperaturen unterscheiden sich um maximal +3 K von den gemessenen Heißpunkttemperaturen. Das verifizierte Gesamtwärmenetz berechnet alle für die Erwärmungsnachweise erforderlichen Temperaturen unter den geforderten Normbedingungen. Bei der normativ geforderten Belastung von 110 % des Bemessungsstroms werden die für den Explosionsschutz maßgeblichen Heißpunkte seitlich auf den druckfesten Kapselungen zweier Schutzschalter berechnet und betragen ϑFZ2 Ob max = 101,6 °C sowie ϑFZ8 Ob max = 101,8 °C. Sowohl für die Erwärmungsnachweise als für das thermische Dimensionieren können mit dem Wärmenetz außerdem Temperaturen an Stellen berechnet werden, die experimentell nur schwer gemessen werden können (z. B. im Bündelzentrum oder im Inneren der druckfesten Kapselungen). Mit dem verifizierten Gesamtwärmenetz werden Fragestellungen zur thermischen Dimensionierung des explosionsgeschützten Energieverteilers rechnerisch beantwortet. So lässt sich u. a. ermitteln, dass der zulässige Bemessungsbelastungsfaktor abhängig von der äußeren Oberflächenbeschaffung des Verteilergehäuses zwischen RDF = 0,55 (innen lackiert, außen hochglanzpoliert) und RDF = 0,78 (innen lackiert, außen lackiert) variiert. Das verifizierte Gesamtwärmenetz ist daher ein geeignetes Werkzeug, um die thermische Dimensionierung zielgerichtet und effizient mittels Erwärmungsberechnung zu unterstützen.:1 Einleitung 1 2 Erkenntnisstand zur Erwärmung von Niederspannungs-Energieverteilern 3 2.1 Wärmequellen 3 2.2 Wärmeübertragung 9 2.3 Erwärmungsberechnung mit der Wärmenetzmethode 19 2.4 Messen von Oberflächentemperaturen 23 2.5 Grenztemperaturen – Rechtliche und normative Vorgaben 25 3 Musteranlage 34 3.1 Aufbau 34 3.2 Hauptwärmequellen 38 4 Präzisieren der Aufgabenstellung 42 5 Untersuchungen zur Temperaturmessung auf druckfesten Kapselungen 45 5.1 Problemstellung 45 5.2 Analyse der Wärmeströme 46 5.3 Untersuchte Montagekonstruktionen 48 5.4 Versuchsaufbau und -durchführung 49 5.5 Ergebnisse 52 5.6 Angepasste Montagetechnik für druckfeste Kapselungen 55 6 Untersuchungen zur Erwärmung der Betriebsmittel 57 6.1 Explosionsgeschützter Fehlerstrom-Schutzschalter mit Überstromauslöser 57 6.2 Explosionsgeschützter Last- und Motorschalter 74 7 Untersuchungen zur gegenseitigen thermischen Beeinflussung der Betriebsmittel 93 7.1 Erwärmung der Leitungsbündel 93 7.2 Zirkulierender Kühlmittelstrom 111 8 Modellbildung 120 8.1 Strukturierter Aufbau – Verfahren 120 8.2 Wärmenetzmodelle 121 9 Verifikation des Wärmenetzmodells der Musteranlage 133 9.1 Versuchsaufbau 133 9.2 Parameterabgleich 138 9.3 Vergleich der Temperaturen 140 10 Anwendung 150 10.1 Erwärmungsnachweise durch Berechnung 150 10.2 Thermische Dimensionierung durch Berechnung 160 11 Zusammenfassung 166 12 Ausblick 170 / Explosion-proof low-voltage switchgear and controlgear assemblies transmit and distribute electrical energy in potentially explosive atmospheres. To ensure safe operation over decades, the assemblies must be thermally dimensioned at least in such a way that normatively defined limit temperatures are not exceeded. Explosion-proof switchgear and controlgear assemblies vary from conventional switchgear assemblies. Because of the explosion protection, electrical devices are installed in flameproof enclosures. The row installation of flameproof enclosed devices is carried out with spacing between each device. The wiring of the devices is often done with cables with heat-resistant insulation. These cables are mainly laid in bundles. The explosion-proof switchgear and controlgear assemblies do not have ventilation openings for additional cooling. For explosion protection, all the highest surface temperatures (hot spots) that could come into contact with ignitable atmosphere are also relevant. The hotspot temperatures must not exceed normatively defined limit temperatures. The Thermal Network Method is an established approach for efficiently calculating the temperature-rise of conventional switchgear and controlgear assemblies. So far, the temperature-rise of explosion-proof switchgear and controlgear assemblies including hot spots could not be calculated with the Thermal Network Method. In this work, the dominant heat sources and heat transfer processes are investigated for of a typical explosion-proof switchgear assembly. Investigation is carried out experimentally as well as by means of numerical methods (Finite Element Method, Finite Volume Method). Based on the results of the investigation, calculation models for the heating of cable bundles and for the velocity of circulating coolant flows are developed and implemented in the Thermal Network Method. In order to calculate hot spot temperatures on flameproof enclosures, finely resolved thermal networks are required for the first time. A method for the design of finely resolved thermal networks is developed. A simple approach for the calculation of the heating of planar contacts is extended in this work to convex switching contacts by determining the apparent contact area from measurements with pressure sensing sheets. Thermal networks for the electrical equipment are set up, parameterized and verified experimentally. The overall thermal network is set-up by interconnecting thermal networks of the operating equipment and verified experimentally. The temperatures calculated with the verified overall thermal network were compared with measured temperatures at 100 % rated current. The temperatures deviate slightly. The highest remaining deviations are ΔΘ = +6.3 K and ΔΘ = -6.2 K. The calculated locations of the hot spots agree with measurement. The calculated hot spot temperatures differ from measured hot spot temperatures slightly by a maximum of +3 K. At the normatively required load of 110 % of the rated current, the hot spots are calculated laterally on the flameproof enclosures of two circuit breakers (ϑFZ2 Ob max = 101.6 °C, ϑFZ8 Ob max = 101.8 °C). The verified overall thermal network calculates all temperatures required for temperature-rise tests of the investigated explosion-proof switchgear assembly. Furthermore, the thermal network can be used to calculate temperatures at locations that are difficult to measure (e.g., at the center of cable bundles or inside the flameproof enclosures). With the verified overall thermal network, questions concerning the thermal dimensioning of the explosion-proof switchgear assembly can be answered computationally. Among other things, it can be determined that the permissible rated diversity factor varies between RDF = 0.55 (internally painted, externally highly polished) and RDF = 0.78 (internally painted, externally painted) depending on the external surface finish of the distributor enclosure. The verified overall thermal network is a suitable tool for supporting thermal dimensioning computationally in a targeted and efficient manner.:1 Einleitung 1 2 Erkenntnisstand zur Erwärmung von Niederspannungs-Energieverteilern 3 2.1 Wärmequellen 3 2.2 Wärmeübertragung 9 2.3 Erwärmungsberechnung mit der Wärmenetzmethode 19 2.4 Messen von Oberflächentemperaturen 23 2.5 Grenztemperaturen – Rechtliche und normative Vorgaben 25 3 Musteranlage 34 3.1 Aufbau 34 3.2 Hauptwärmequellen 38 4 Präzisieren der Aufgabenstellung 42 5 Untersuchungen zur Temperaturmessung auf druckfesten Kapselungen 45 5.1 Problemstellung 45 5.2 Analyse der Wärmeströme 46 5.3 Untersuchte Montagekonstruktionen 48 5.4 Versuchsaufbau und -durchführung 49 5.5 Ergebnisse 52 5.6 Angepasste Montagetechnik für druckfeste Kapselungen 55 6 Untersuchungen zur Erwärmung der Betriebsmittel 57 6.1 Explosionsgeschützter Fehlerstrom-Schutzschalter mit Überstromauslöser 57 6.2 Explosionsgeschützter Last- und Motorschalter 74 7 Untersuchungen zur gegenseitigen thermischen Beeinflussung der Betriebsmittel 93 7.1 Erwärmung der Leitungsbündel 93 7.2 Zirkulierender Kühlmittelstrom 111 8 Modellbildung 120 8.1 Strukturierter Aufbau – Verfahren 120 8.2 Wärmenetzmodelle 121 9 Verifikation des Wärmenetzmodells der Musteranlage 133 9.1 Versuchsaufbau 133 9.2 Parameterabgleich 138 9.3 Vergleich der Temperaturen 140 10 Anwendung 150 10.1 Erwärmungsnachweise durch Berechnung 150 10.2 Thermische Dimensionierung durch Berechnung 160 11 Zusammenfassung 166 12 Ausblick 170

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Under den senaste tiden har det upplevts en större oro i omvärlden och fred är inte längreen självklarhet i Europa. Människor är oroliga för den eskalerande situationen i Europaoch det har skapat ett osäkert säkerhetspolitiskt läge i världen. Befintlig konstruktion,fasta installationer och människor kan i framtiden hamna i risk för allvarliga skador frånexplosioner. Detta är ett samhällsproblem som det bör finnas en lösning till. C3CEngineering AB är ett skandinaviskt företag som tillverkar prefabricerade betongblock avtill största del återvunnen betong. Betongblocken är utformade enligt lego-principen ochär lätta att etablera och stapla på varandra. Befintliga muruppställningar och blocktillämpas vid flera olika användningsområden, exempelvis återvinningscenter ochinfrastruktur. Betongblocken kan även ha betydande användning som skydd vidkrissituationer.Syftet med arbetet var att utforma olika muruppställningar med betongelement från C3CEngineering AB för skydd mot explosioner. Muruppställningarna skall fungera som enskyddsbarriär vid kris och skydda bakomliggande objekt och människor bakom muren.Betongblock C3Cblock® 1688 har använts för de olika muruppställningarna eftersom detfinns ett stort lagersaldo av blocken i Sverige. Blockdimensionen är (1600 x 800 x 800millimeter) och blocken har beräknats från minsta tillverkningshållfasthet C20/25.En explosionslast är en dynamisk belastning på en konstruktion. En statiskt ekvivalentlast har använts vid beräkningarna för detta arbete. Blocken och muruppställningarna harundersökts utifrån vilka dimensionerande laster de klarar av samt vid olikabelastningsfall. Vid dimensionering har splitterverkan, hållfasthet, skjuvning,dymlingsverkan, glidning, stjälpning, markbärighet och inverkan av utböjningkontrollerats. Splitterverkan har kontrollerats utifrån MSB:s dokument för skyddsrum ochbetonghållfasthet har kontrollerats enligt Eurocode 2. Intervjuer med en teknisk specialistfrån MSB har utförts för att få en korrekt beskrivning av explosionslasternas beteende.Målet är att blocken skall kunna användas i både fredstid och vid en eventuellkrissituation. Blocken kan användas i offentliga miljöer som bullerskydd ellerläktarplatser och kan snabbt etableras som skyddsmurar vid behov.Resultatet visar att murar utformade med längre hävarmar klarar generellt av störredimensionerande laster vid stjälpning. Vid användningen av kontreforer kan murar medfärre betongblock motstå samma dimensionerande laster jämfört med bredare och tyngremurar utan kontreforer. Densiteten hos betongelementen är betydelsefull i fleradimensionerade lastfall.Arbetets avgränsningar leder till att de angivna statiskt ekvivalenta lasterna från resultatetkan inte kopplas till exakta dynamiska laster från en specifik explosion. Vidare forskningrelaterad till hur dynamiska laster på muruppställningarna beräknas om till statisktekvivalenta laster är en förutsättning för att besvara detta.Endast en typ av betongblock har använts för att modellera murarna och användningen avandra blocktyper kan resultera i andra murar med nya dimensioner och dimensionerandelaster. / In order to account for the rising risk of injury and damage to structures and people fromexplosions, the use of mobile and stable concrete protection walls is more relevant thanever. The Scandinavian company C3C Engineering AB designs and produces concreteelements which can interlock using the lego principle. The load capacity before criticalfailure of protective walls using C3Cblock® 1688 has been investigated in this study.Several failure modes such as shrapnel damage, sliding and foundation deformation wasstudied, to name a few. For each type of protective wall and failure stats a maximum loadcapacity was calculated.The study intended to answer which failure mode occurs first for each type of protectivewall. The deciding factors that determine a wall's maximum load capacity againstexplosions were also studied and analysed.The results are based on calculations using Mathcad Prime 7.0.0, and interviews withemployees at C3C Engineering AB and consultants for Myndigheten för samhällsskyddoch beredskap (MSB). For control of concrete, formulas and values from Eurocode 2were used.The results indicate that the protective wall's leverage length is a decisive factor forseveral failure modes, followed by the total weight of the construction. Increasing thedensity for the concrete elements result in heavier walls and thus greatly benefits theconstruction as a whole.

Underwater explosions (UNDEX) and a ship's vulnerability to them are problems of interest in early-stage ship design. A series of events occur sequentially in an UNDEX scenario in both the fluid and structural domains and these events happen over a wide range of time and spatial scales. Because of the complexity of the physics involved, it is a common practice to separate the description of UNDEX into early-time and late-time, and far-field and near-field. The research described in this dissertation is focused on the simulation of near-field and early-time UNDEX. It assembles a hybrid framework of algorithms to provide results while maintaining computational efficiency. These algorithms include Runge-Kutta, Discontinuous Galerkin, Level Set, Direct Ghost Fluid and Embedded Boundary methods. Computational fluid dynamics (CFD) solvers are developed using this framework of algorithms to demonstrate the computational methods and their ability to effectively and efficiently solve UNDEX problems. Contributions, made in the process of satisfying the objective of this research include: the derivation of eigenvectors of flux Jacobians and their application to the implementation of the slope limiter in the fluid discretization; the three-dimensional extension of Direct Ghost Fluid Method and its application to the multi-fluid treatment in UNDEX flows; the enforcement of an improved non-reflecting boundary condition and its application to UNDEX simulations; and an improvement to the projection-based embedded boundary method and its application to fluid-structure interaction simulations of UNDEX problems. / Doctor of Philosophy / Underwater explosions (UNDEX) and a ship's vulnerability to them are problems of interest in early-stage ship design. A series of events occur sequentially in an UNDEX scenario in both the fluid and structural domains and these events happen over a wide range of time and spatial scales. Because of the complexity of the physics involved, it is a common practice to separate the description of UNDEX into early-time and late-time, and far-field and near-field. The research described in this dissertation is focused on the simulation of near-field and early-time UNDEX. It assembles a hybrid framework of algorithms to provide results while maintaining computational efficiency. These algorithms include Runge-Kutta, Discontinuous Galerkin, Level Set, Direct Ghost Fluid and Embedded Boundary methods. Computational fluid dynamics (CFD) solvers are developed using this framework of algorithms to demonstrate these computational methods and their ability to effectively and efficiently solve UNDEX problems.

Combustion of coal is one of the primary sources of electricity generation worldwide today. Coal contains different chemicals that cause particulate matter(PM) and sulfur dioxide (SO2) emissions. These are health hazards and are responsible for deteriorating the ambient air quality. Particulate matter also forms ash deposits inside the coal combustor, which in turn decreases the energy efficiency of the power plants. Using biomass as a fuel in these utility boilers can potentially reduce the problems of particulate matter emissions and ash deposition, and can significantly reduce the SO2 emissions. However, biomass needs to be pretreated to make its properties similar to coal in terms of energy density, grindability, and durability before it can be fired in utility boilers. Steam explosion is one of the leading biomass pretreatment methods that enhances the physicochemical properties of biomass. A comprehensive review of the steam explosion process, its product properties, its comparison with other treatment processes, as well as its economic analysis and lifecycle assessment, have been explored in this work. Steam-exploded biomass has been co-combusted with bituminous coal in a 1500 kWth combustor to analyze the ash aerosol particle size distribution, composition, and deposition behavior. The primary results of these tests showed that both particulate matter emissions and ash deposition amount reduced significantly as more biomass was co-fired with coal. The submicron-sized particulate matter concentration showed a high correlation with the final mass of ash deposits (R2 > 0.96). Predicting ash deposition rates is important during the combustion of solid fuels. A Machine Learning tool was applied and trained with a fuel composition database of 92 fuels obtained from a thermodynamic equilibrium software (FactSage). When fully operational, this model should be integrated with an existing ash deposition model, which should make it self-sufficient in terms of generating equilibrium composition data. SO2 emissions were analyzed during the co-combustion of biomass and coal, and a synergistic decrease in SO2 emissions was observed with higher biomass blends. Experiments were conducted in a full-scale 471 MWe furnace to analyze the SO2 emissions, and an 85%-15% blend of coal and biomass was responsible for a 28.1% reduction in emissions and 22.1% reduction in the lime slurry utilization in the flue gas desulfurization (FGD) towers compared to pure coal combustion. Ash deposit characterizations by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) combined with thermodynamic equilibrium simulations revealed that calcium and potassium were responsible for this synergistic reduction as these metals captured the SO2 from the flue gases and retained them in the ash phase. The SO2 research was important since the current literature is deficient in research conducted at suspension-fired full-scale utility boilers to reduce SO2 emissions by co-firing coal and biomass blends. The research in this dissertation should provide valuable insights to the energy industries that are considering a transformation of fuel portfolio from coal to biomass and explore how the mineral matter present in pretreated biomass would behave inside a utility boiler. The primary conclusions are that during the co-combustion of coal and biomass, ash deposition mass and particulate matter ash load decreased, and SO2 emission saw a synergistic reduction in emissions due to higher calcium and potassium content in biomass compared to pure coal combustion.

Notre étude relève d’une analyse exploratoire fondée sur une étude de cas. En partant d’un exemple de débat articulé autour d’un enjeu public, en l’occurrence la responsabilité sociale d’entreprise (RSE), nous appréhendons le discours comme un instrument de pouvoir déployé par des acteurs en position conflictuelle. Nous prenons comme un cas d’étude la crise écologique provoquée par British Petroleum (BP) au large du Golfe de Mexique le 20 avril 2010. Pour sélectionner notre corpus, nous avons désigné deux populations cibles de discours, en l’occurrence le discours tenu par le gouvernement américain (discours d’Obama) et le discours représentant l’avis officiel de BP (communiqués de presse de BP). Nous avons analysé les discours publics d’Obama et de BP datant du 20 avril 2010 jusqu’au 19 septembre 2010. Nous avons considéré tout discours produit dans un contexte conflictuel travaillé par une crise comme un instrument porteur symboliquement des signes de pouvoir et mobilisant des rapports de force entre les acteurs impliqués. Nous partons de l’hypothèse suivante : les discours organisationnel et gouvernemental étudiés et produits dans un contexte de crise, sont forcément des discours conflictuels au sens de Windisch (1987). Et nous avons utilisé la grille d’analyse élaborée par Windisch (1987) pour mettre en exergue le fonctionnement interne d’un discours conflictuel envisagé comme un vecteur du pouvoir et de légitimation. Nous avons précédé l’analyse de discours, méthode principale dans notre étude, par une analyse de contenu qualitative. Le recours à l’analyse de contenu se justifie par notre souci de déterminer les divers thèmes développés dans le discours, d’examiner comment les acteurs imprègnent de sens le thème de la RSE et de poser le corpus dans sa réalité propre, en ayant recours au logiciel d’analyse de contenu qualitative HYPERRESEARCH. En outre, en mobilisant les présupposés théoriques et les outils méthodologiques issus de l’analyse de discours, nous avons ausculté le potentiel performatif légitimateur des discours construits et élaborés dans un contexte de communication conflictuelle. Pour ce faire, nous avons utilisé le logiciel d’analyse textuelle TROPES reconnu comme un outil d’analyse textuelle capable de générer des modèles représentatifs de la structure du corpus et de son organisation thématique. NOTIONS-CLÉS Discours conflictuel, stratégies discursives, RSE, légitimité, pouvoir, tandem État/firme. / Our study is intended to be an exploratory analysis based on a case study. Starting from a sample debate articulated around a public issue, namely the corporate social responsibility (CSR), we apprehend the discourse as an instrument of power deployed by actors in a conflict position. We take the ecological crisis caused by British Petroleum (BP) in the Gulf of Mexico since April 20, 2010 as a case study, and the reaction of the U.S. administration to intervene and reassure the public opinion alarmed by this crisis. In order to select our corpus, we have identified two target populations of discourse, in this case the speech given by the U.S. government (Obama's speech) and discourses representing the official opinion of BP (BP's press releases) dated April 20, 2010 until September 19, 2010. We considered any discourse occurring in a context of conflict symbolically as a power signs carrier and a mobilizing instrument of power relations between the involved actors. We start from the hypothesis stating that organizational and governmental discourses, studied and produced in a crisis context, are necessarily conflictual discourses within the meaning of Windisch (1987). And we used the analytical framework developed by Windisch (1987) to highlight the internal functioning of a confrontational speech seen as a vector of power and legitimacy. In our research, we preceded the discourse analysis, the main method in our study, by a qualitative content analysis. The use of content analysis aims to determine the various themes developed in the discourse, examine how actors define the CSR topic and put the corpus in its own reality, by using the HYPERRESEARCH qualitative content analysis software. In addition, by implementing the theoretical assumptions and methodological tools from discourse analysis, we auscultated the performative legitimating potential of discourses constructed and developed in a conflict communication context. We used the TROPES text analysis software recognized as a textual analysis tool able to generate representative models of the corpus structure and its thematic organization. KEY CONCEPTS Confrontational discourse, discursive strategies, CSR, legitimacy, power, tandem of government and enterprise.

State explosion in model checking continues to be the primary obstacle to widespread use of software model checking. The large input ranges of variables used in software is the main cause of state explosion. As software grows in size and complexity the problem only becomes worse. As such, model checking research into data abstraction as a way of mitigating state explosion has become more and more important. Data abstractions aim to reduce the effect of large input ranges. This work focuses on a static program analysis technique called dead variable analysis. The goal of dead variable analysis is to discover variable assignments that are not used. When applied to model checking, this allows us to ignore the entire input range of dead variables and thus reduce the size of the explored state space. Prior research into dead variable analysis for model checking does not make full use of dynamic run-time information that is present during model checking. We present an algorithm for intraprocedural dead variable analysis that uses dynamic run-time information to find more dead variables on-the-fly and further reduce the size of the explored state space. We introduce a definition for the maximal state space reduction possible through an on-the-fly dead variable analysis and then show that our algorithm produces a maximal reduction in the absence of non-determinism.

Few experimental techniques have found such a diverse range of applications as has ion imaging. The field of chemical dynamics is constantly advancing, and new applications of ion imaging are being realised with increasing frequency. This thesis is concerned with the application of a fast pixelated imaging sensor, the Pixel Imaging Mass Spectrometry (PImMS) camera, to ion imaging applications. The experimental possibilities of such a marriage are exceptionally broad in scope, and this thesis is concerned with the development of a selection of velocity-map imaging applications within the field of photoinduced molecular dynamics. The capabilities of the PImMS camera in three-dimensional and slice imaging applications are investigated, in which the product fragment Newton-sphere is temporally stretched along the time-of-flight axis, and time-resolved slices through the product fragment distribution are acquired. Through experimental results following the photodissociation of ethyl iodide (CH₃CH₂I) at around 230 nm, the PImMS camera is demonstrated to be capable of recording well-resolved time slices through the product fragment Newton-sphere in a single experiment, without the requirement to time-gate the acquisition. The various multi-hit capabilities of the device represent a unique and significant advantage over alternative technologies. The details of a new experiment that allows the simultaneous imaging of both photoelectrons and photoions on a single detector for each experimental acquisition cycle using pulsed ion extraction are presented. It is demonstrated that it is possible to maintain a high velocity resolution using this approach through the simultaneous imaging of the photoelectrons and photoions that result from the (3 + 2) resonantly enhanced multi-photon ionisation of Br atoms produced following the photodissociation of Br₂ at 446.41 nm. Pulsed ion extraction represents a substantial simplification in experimental design over conventional photoelectron-photoion coincidence (PEPICO) imaging spectrometers and is an important step towards performing coincidence experiments using a conventional ion imaging apparatus coupled with a fast imaging detector. The performance of the PImMS camera in this application is investigated, and a new method for the determination of the photofragment detection efficiencies based on a statistical fitting of the coincident photoelectron and photoion data is presented. The PImMS camera is applied to laser-induced Coulomb explosion imaging (CEI) of an axially chiral substituted biphenyl molecule. The multi-hit capabilities of the device allow the concurrent detection of individual 2D momentum images of all ionic fragments resulting from the Coulomb explosion of multiple molecules in each acquisition cycle. Correlations between the recoil directions of the fragment ions are determined through a covariance analysis. In combination with the ability to align the molecules in space prior to the Coulomb explosion event, the experimental results demonstrate that it is possible to extract extensive information pertaining to the parent molecular structure and fragmentation dynamics following strong field ionisation. Preliminary simulations of the Coulomb explosion dynamics suggest that such an approach may hold promise for determining elements of molecular structure on a femtosecond timescale, bringing the concept of the `molecular movie' closer to realisation. Finally, the PImMS camera is applied to the imaging of laser-induced torsional motion of axially chiral biphenyl molecules through femtosecond Coulomb explosion imaging. The target molecules are initially aligned in space using a nanosecond laser pulse, and torsional motion induced using a femtosecond 'kick' pulse. Instantaneous measurements of the dihedral angle of the molecules are inferred from the correlated F+ and Br+ ion trajectories following photoinitiated Coulomb explosion at various time delays after the initial kick pulse. The technique is extended to include a second kick pulse, in order to achieve either an increase in the amplitude of the oscillations or to damp the motion, representing a substantial degree of control of the system. Measurements out to long kick-probe delays (200 ps) reveal that the initially prepared torsional wave packet periodically dephases and rephases, in accordance with the predictions of recent theoretical work.

La première partie est une étude de l'évolution de la population des nuages HI en présence d'un milieu internuage de type coronal, entretenu par les explosions de supernova. La seconde partie concerne l'évolution d'un reste de supernova dans un milieu interstellaire hétérogene. La troisième partie propose un modèle dynamique de nébuleuse planétaire dont la morphologie et la dynamique doivent leur origine à une cavité centrale remplie de gaz coronal.

This research is aimed at exploding a wire via electromagnetic induction, with a preference for obtaining restrike of the exploding wire in a ring shape or otherwise. Literature on both exploding wire and electromagnetic induction are introduced together. A mathematical framework to describe the wire explosion by induction is formulated from first principles using the idea of magnetic flux linkages. The environment in which the experiments took place is described, with reference to matters of laboratory safety and also measurement of transient electrical current and voltage in the wire explosion by induction. The results describe the approaches taken to explode a wire by induction to obtain a plasma conductor. Voltage and current data are displayed and described. Throughout this work, there are long-exposure digital photographic images of the experiments taking place. These contribute to determining the outcome of experiments, and support the conclusions. Wires were exploded by induction in an air-cored mutually coupled coils system, and restrike of those wires was achieved. Electrical characteristics of wire explosion by electromagnetic induction are displayed and discussed based on what is known about straight exploding wires. Future works involving creation of plasma rings, electromagnetic thrust and exploding wires in vacuum are discussed.