By means of N-body simulations we study the ion and electron dynamics in molecular first-row hydride clusters when exposed to intense and short X-ray pulses. We find that, for a particular range of X-ray intensities, fast protons are ejected from the system on a considerably shorter time scale than that of the screened core. As a consequence, the structure of heavy atoms is kept intact", which may be relevant in the context of X-ray based molecular imaging. Moreover the final charge states of the heavy ions are considerably lower than those of the ions in pristine atomic clusters exposed to the same laser pulses, which is in agreement with recent measurement of methane cluster at the LCLS in Stanford.

When a nuclear explosion occurs certain radionuclides are emitted, notably xenon. Due to the fact that xenon is a noble gas, it is hard to contain and can therefore be detected far from the explosion site. There are four isotopes of xenon that are of interest in the detection of a nuclear explosion: 131mXe, 133mXe, 133Xe and 135Xe. By constantly measuring the amount of these isotopes in the air, changes in the concentration in an indication that a nuclear explosion has occurred. In this thesis a detector was modelled in GEANT4 and focuses on one kind of noble gas detector: SAUNA - the Swedish Automatic Unit for Noble gas Acquisition. SAUNA uses the coincidence technique in order to determine the concentration of xenon there is in the air. By using the coincidence technique, it is possible to reduce the impact of the background radiation and therefore increase the efficiency of the detector. 133Xe has a coincidence when it first undergoes beta decay, with an endpoint energy of 346 keV, and then emits a 80 keV gamma particle. 135Xe has also a dual coincidence, a beta decay with an endpoint energy of 910 keV together with a 250 keV gamma-ray. However both these isotopes have a triple coincidence decay that also can be exploited: for 133Xe, a beta particle with endpoint energy of 346 keV, a 30 keV X-ray and a 45 keV conversion electron, while for 135Xe there is instead of the gamma particle a 30 keV X-ray and a 214keV conversion electron that can be emitted together with the beta particle. The 30 keV X-ray together with the beta particle for 133Xe can also be used as a dual coincidence, in that case the conversion electron is ignored. For 133Xe, when a beta particle, a 45 keV conversion electron, and a 30 keV X-ray are emitted, the model was able to detect all three particles in 69.2% ± 0.1 of the cases. However, when only the particles with a detected energy within a 5 keV interval of their generated energies are considered to be in coincidence, then for 133Xe triple coincidence occurs in 22.9% ± 0.2 of the cases. For 135Xe the model was able to detect the triple coincidence (between a beta, 214 keV CE and 30 keV X-ray) in 63.5% ± 0.1 of the cases. This work shows that adding another particle in a coincidence reduces the chance to detect the coincidence. The positive effect of adding another particle in a coincidence is that the minimum detectable concentration of xenon should be smaller. The goal for future detectors should be to make it possible for the detector to take advantage of the triple coincidences but at the same time be also able to use the dual coincidences.

Förbehandling av lignocellulosa genom ångexplosion är en förbehandling av biomassa som förändrar strukturen i fibrernas cellväggar. Vid förbehandlingen värms biomassa med mättad ånga under tryck till minst 140 ˚C, detta leder till att flyktiga ämnen avgår från biomassan. När den uppvärmda biomassan är färdigbehandlad utsätts den för en kraftig trycksänkning vilket leder till att fukten i biomassan övergår till ånga och bidrar till ökad porositet, minskad materialstorlek och förändrad struktur i cellväggarna. Genom kartläggning av ett befintligt kokkärl på SCA R&D Centre och litteraturstudier inom området utforskas möjligheten att bygga om kokkärlet till ångexplosionsreaktor för laborativt bruk. Ett utformningsförslag togs fram varpå en termodynamisk modell över reaktionen skapades i Excel med hjälp av makrot Xsteam. Dimensionering av blåstank till förslaget gjordes baserat på ångexplosion av två kg tallflis med två fukthalter, 40 och 60%. Resultaten visar att en ombyggnation är möjlig, ångpannan begränsar dock ångtrycket till 10 bar. Vid behandling av två kg tallflis med en fukthalt om 40 respektive 60% dimensionerades anläggningens blåstank till 376 respektive 493 liter. Den nya reaktorn designades som skild från atmosfären. En sådan reaktor möjliggör framtida analys av bland annat flyktiga ämnen vilket kan bidra till effektivare tillvaratagande av restströmmar. / Pretreatment of lignocellulose by steam explosion is an energy efficient method that alters the structure of the fiber cell walls. Biomass is heated with pressurized saturated steam during the pretreatment to at least 140˚C, causing the release of volatile substances. Once the heated biomass is treated to desired severity, it undergoes a significant pressure reduction, causing the moisture in the biomass to turn into steam and contribute to increased porosity, reduced particle size and altered structure in the fiber cell walls. By examining an existing digester at the SCA R&D Centre and conducting literature studies in the field, the possibility of converting the digester into a steam explosion reactor for laboratory use is explored. A design proposal was developed, upon which a thermodynamic model of the reaction was created in Excel using the Xsteam macro. Dimensioning of the blow tank for the proposal was based on steam explosion of two kg pine chips with two moisture levels, 40% and 60%. The results indicate that such a conversion is possible, however, the steam pressure is limited to 10 bar overpressure due to the existing steam boiler. When treating two kg of pine chips with moisture content of 40% and 60% respectively, the sizing of the blow tank for the facility was determined to be 376 liters and 493 liters respectively. The new reactor was designed to be isolated from the atmosphere, enabling future analysis of volatile substances, which can contribute to a more efficient utilization of residual streams.

This master's thesis examines the importance of the explosion incident at Nord Stream and Russia’s full-scale invasion of Ukraine on Sweden’s security sectors. The critical energy project Nord Stream 1 and its expansion to Nord Stream 2 have created bipolar attitudes and debates in Sweden and the EU regarding the security implications of increased Russian power. The Ukraine war and the physical attack on the pipelines have only amplified security concerns in the international political arena. This thesis aims to provide a descriptive understanding of the explosion incident and Russia’s aggressive actions in Ukraine and their resulting impact on Sweden’s ability to establish a stable security strategy viewed by security sectors such as national-, environmental-, energy-, military-, economic-, human-, and societal-security. Additionally, this thesis also explores these issues from Sweden’s perspective with the use of classic international relations perspectives such as realism and liberalism. Results present that the security sector reports heightened tensions, with Russia potentially increasing military activities. New intensified threat perception for Sweden, negative environmental impacts, affecting on human health and security. Effects regarding energy security. New security threats for Russia's establishment within the European market, impact and effects on nations' identity and uncertainty about the new political situation, and increased insecurity for essential societal infrastructures.

No description available.

A coupled solution approach is presented for numerically simulating a near-field underwater explosion (UNDEX). An UNDEX consists of a complicated sequence of events over a wide range of time scales. Due to the complex physics, separate simulations for near/far-field and early/late-time are common in practice. This work focuses on near-field early-time UNDEX simulations. Using the assumption of compressible, inviscid and adiabatic flow, the fluid flow is governed by a set of Euler fluid equations. In practical simulations, we often encounter computational difficulties that include large displacements, shocks, multi-fluid flows with cavitation, spurious waves reflecting from boundaries and fluid-structure coupling. Existing methods and codes are not able to simultaneously consider all of these characteristics. A robust numerical method that is capable of treating large displacements, capturing shocks, handling two-fluid flows with cavitation, imposing non-reflecting boundary conditions (NRBC) and allowing the movement of fluid grids is required. This method is developed by combining numerical techniques that include a high-order accurate numerical method with a shock capturing scheme, a multi-fluid method to handle explosive gas-water flows and cavitating flows, and an Arbitrary Lagrangian Eulerian (ALE) deformable fluid mesh. These combined approaches are unique for numerically simulating various near-field UNDEX phenomena within a robust single framework. A review of the literature indicates that a fully coupled methodology with all of these characteristics for near-field UNDEX phenomena has not yet been developed. A set of governing equations in the ALE description is discretized by a Runge Kutta Discontinuous Galerkin (RKDG) method. For multi-fluid flows, a Direct Ghost Fluid (DGF) Method coupled with the Level Set (LS) interface method is incorporated in the RKDG framework. The combination of RKDG and DGF methods (RKDG-DGF) is the main contribution of this work which improves the quality and stability of near-field UNDEX flow simulations. Unlike other methods, this method is simpler to apply for various UNDEX applications and easier to extend to multi-dimensions. / Ph. D.

Résumé : Le sepsis sévère et le choc septique réfractaire sont d’incidences grandissantes dans la population et restent actuellement un défi de taille avec une mortalité variant de 30 à 70 % à 28 jours malgré l’amélioration du traitement de support. Les corticostéroïdes (CS) sont un traitement d’appoint controversé dans le sepsis sévère et le choc septique réfractaire. Ils modulent entre autre les fonctions des neutrophiles ou polymorphonuclear neutrophils cells (PMN) qui sont des acteurs de 1ère ligne dans la défense immédiate contre le sepsis et les défaillances organiques associées. Résultats : Le sepsis a pour effet de diminuer l’activité phagocytaire, ainsi que la production de radicaux libres oxygénés (ROS) des PMN au jour 1 (J1) et jour 3 (J3). Il augmente l’adhésion qui s’intensifie avec la sévérité de la maladie et persiste jusqu’à J3. Au niveau de la dégranulation, le sepsis augmente la production et la libération de la pentraxine 3 (PTX3). Le sepsis affecte le profil phénotypique des PMN en augmentant l’expression de CD66b et ST2 à J1 et J3. Il accentue également l’expression de CD64. Dans le groupe 2 (G2), ce niveau d’expression diminue à J3. Aucun effet significatif sur le chimiotactisme n’a été observé à J1, ni J3. L’usage de CS in vitro retarde l’apoptose à J1 et J3 dans le groupe 1 (G1), mais ne démontre aucune amélioration significative des fonctions des PMN ou au niveau de leur profil phénotypique. Conclusion : Le sepsis entraîne une immunoparalysie des PMN au niveau de leur migration et des fonctions effectrices. Non seulement cette paralysie augmente avec la sévérité de la maladie, mais elle persiste également après 3 jours suivant l’admission. De faibles doses de CS in vitro et in vivo dans le traitement du choc septique n’ont pas d’effet déterminant sur les PMN dans l’amélioration du pronostic des patients. Davantage de recherches seront nécessaires afin d’approfondir notre compréhension de l’impact d’un traitement aux CS sur les fonctions neutrophiliques dans un contexte septique. Ces derniers permettraient non seulement de mieux cibler leur utilisation dans le but d’arriver à un rapport bénéfique/risque avantageux dans le choc septique, mais aussi pour d’autres maladies inflammatoires. / Abstract : With the increasing rates of severe sepsis and refractory septic shock, there is still a challenge in mortality rates between 30 and 70 % at 28 days despite improved supportive care. Corticosteroids (CS) are a controversial supportive treatment in severe sepsis and refractory septic shock. They modulate the functions of PMN that are players in first line of immediate defence against the sepsis and associated to multiorgan failures. Results : Sepsis leads to a reduced phagocytic activity and ROS production at day 1 (D1) and day 3 (D3). It enhances the adhesion which increases with the severity of sepsis and persists until D3. In terms of degranulation, the sepsis increases the production and release of PTX3. Sepsis affects the phenotypic profile of PMN that increases the expressions of CD66b and ST2 at D1 and D3. It increases the CD64 expression but decreased at D3 in G2. No significant effect on chemotaxis was observed in D1, neither in D3. In G1, use of CS in vitro further delays apoptosis at D1 and D3, but is not showing any improvement in functions of PMN or in phenotypic profile. Conclusions : Sepsis induces an immune paralysis of PMN in their migration and effectives functions. Not only this paralysis increases with the severity of the sepsis, but it also persists after 3 days following the admission. Low doses of CS in vitro and in vivo in the treatment of septic shock have not determinant effect on PMN in improvement of the outcome of patients. More research is needed to learn more about the impacts of CS treatment on PMN functions in sepsis. This would contribute not only to ensure a better target ing of their use in order to achieve an advantageous benefits/risks ratio in septic shock, but also for others inflammatory diseases.

The performance modelling of large-scale systems using discrete-state approaches is fundamentally hampered by the well-known problem of state-space explosion, which causes exponential growth of the reachable state space as a function of the number of the components which constitute the model. Because they are mapped onto continuous-time Markov chains (CTMCs), models described in the stochastic process algebra PEPA are no exception. This thesis presents a deterministic continuous-state semantics of PEPA which employs ordinary differential equations (ODEs) as the underlying mathematics for the performance evaluation. This is suitable for models consisting of large numbers of replicated components, as the ODE problem size is insensitive to the actual population levels of the system under study. Furthermore, the ODE is given an interpretation as the fluid limit of a properly defined CTMC model when the initial population levels go to infinity. This framework allows the use of existing results which give error bounds to assess the quality of the differential approximation. The computation of performance indices such as throughput, utilisation, and average response time are interpreted deterministically as functions of the ODE solution and are related to corresponding reward structures in the Markovian setting. The differential interpretation of PEPA provides a framework that is conceptually analogous to established approximation methods in queueing networks based on meanvalue analysis, as both approaches aim at reducing the computational cost of the analysis by providing estimates for the expected values of the performance metrics of interest. The relationship between these two techniques is examined in more detail in a comparison between PEPA and the Layered Queueing Network (LQN) model. General patterns of translation of LQN elements into corresponding PEPA components are applied to a substantial case study of a distributed computer system. This model is analysed using stochastic simulation to gauge the soundness of the translation. Furthermore, it is subjected to a series of numerical tests to compare execution runtimes and accuracy of the PEPA differential analysis against the LQN mean-value approximation method. Finally, this thesis discusses the major elements concerning the development of a software toolkit, the PEPA Eclipse Plug-in, which offers a comprehensive modelling environment for PEPA, including modules for static analysis, explicit state-space exploration, numerical solution of the steady-state equilibrium of the Markov chain, stochastic simulation, the differential analysis approach herein presented, and a graphical framework for model editing and visualisation of performance evaluation results.

Approved for public release; distribution is unlimited / In 2001 the USS WINSTON CHURCHILL (DDG-81) was subjected to three underwater explosions as part of a ship shock trial. Using the actual trial data from experiment and three-dimensional dynamic models of the ship and surrounding fluid very successful comparisons of the vertical motion have been achieved. On average, the magnitude of the vertical motion is three to four times the magnitude of athwartship motion. Previous simulations of this athwartship motion have been less accurate than the vertical motion simulations. This thesis examines recent efforts attempted to improve the simulation results of the athwartship motion including shock spectra analysis, and the reasons behind the disparities that exist between the simulated values and the actual trial data. / Lieutenant, United States Coast Guard

Dans cette thèse, nous nous intéressons aux équations aux dérivées fractionnaires et leurs applications au traitement d'images. Une attention particulière a été apportée à un système non linéaire d'équations différentielles fractionnaires. En particulier, nous avons étudié les propriétés qualitatives des solutions d'un système non linéaire d'équations différentielles fractionnaires qui explosent en temps fini. L'existence des solutions locales pour le système, le profil des solutions qui explosent en temps fini sont présentés. Nous étudierons le problème inverse pour l'équation de diffusion linéaire en une dimension et en deux dimensions. Nous sommes intéressés par trouver un terme source inconnu d'une équation de diffusion non locale. Les conditions aux limites considérées sont non locales et le problème spectral est non auto-adjoint. L'existence et l'unicité de la solution du problème inverse sont présentées.D'autre part, nous proposons un modèle basé sur l'équation de la chaleur linéaire avec une dérivée fractionnaire en temps pour le débruitage d'images numériques. L'approche utilise une technique de pixel par pixel, ce qui détermine la nature du filtre. En contraste avec certain modèles basés sur les équations aux dérivées partielles pour le débruitage de l'image, le modèle proposé est bien posé et le schéma numérique est convergent. Une amélioration de notre modèle proposé est suggéré. / In this thesis we study a nonlinear system of fractional differential equations with power nonlinearities; the solution of the system blows up in a finite time. We provide the profile of the blowing-up solutions of the system by finding upper and lower estimates of the solution. Moreover, bilateral bounds on the blow-up time are given.We consider the inverse problem concerning a linear time fractional diffusion equation for the determination of the source term (supposed to be independent of the time variable) and temperature distribution from initial and final temperature data. The uniqueness and existence of the continuous solution of the inverse problem is proved. We also consider the inverse source problem for a two dimensional fractional diffusion equation. The results about the existence, uniqueness and continuous dependence of the solution of the inverse problem on the data are presented.We apply the linear heat equation involving a fractional derivative in time for denoising (simplification, smoothing, restoration or enhancement) of digital images. The order of the fractional derivative has been used for controling the diffusion process, which in result preserves the fine structures in the image during denoising process. Furthermore, an improvement in the proposed model is suggested by using the structure tensor of the images.