High power high efficiency multiple-beam klystron design

This thesis investigated the design decisions and associated optimisation methods of a 1.3 GHz Multiple Beam Klystron (MBK) for use in the Compact Linear Collider (CLIC). In this regard refinements have been made both to the MBK design, and investigation and optimisation methods used. The high desired efficiency of 80% requires low perveance beams, to achieve the specification output power 20 beams are needed. The choice of cavity used in the interaction structure of a klystron has a large impact on its size and efficiency. To optimise this a number of possible cavity designs were produced and compared to confirm selection of the most appropriate. The fundamental mode (TM0, 1, 0) coaxial cavity was selected due to its superior R/Q of 130-210 W and suitability as a 2nd harmonic cavity. Although the dipole mode proved to be close in frequency to the operating mode (within ~ 50 MHz), raising concerns of stability issues in an MBK. A novel model was developed using standard wake field theory to investigate the effects of this mode the klystron’s stability. A strategy for shifting this mode using a coupled shifting gap was proposed and achieves a shift of 125 MHz, although the models findings suggest it is not a significant problem. Existing methods of calculating dipole and higher order modes proved time consuming thus impeded a fully investigation of stability issues. An extended method of moments model allows efficient calculation of monopole and higher order modes. The model’s basis functions are altered to represent a range of TM and TE modes with azimuthal variation, allowing their rapid and accurate calculation. Optimising the klystron interaction structure by hand to find a viable configuration revealed shortcomings in this standard approach, although the target efficiency was achieved. An algorithmic approach was deemed necessary to allow a full investigation within reasonable time limits. The field of evolutionary algorithms is presented and an evolutionary algorithm to automate the optimisation of klystron interaction structures was developed. A number of important related issues were dealt with and suitable interaction structures (optimised for efficiency, bandwidth, length and electron exit velocity) produced. Finally a design was proposed for both the input and output couplers which is inspired by a coupler used in a gyrotron. Unconventionally, the latter exits the tube axially avoiding the focusing solenoid, but excessive heating may preclude its use

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version

Investigation into the changing colonisation of skin bacteria during isotretinoin treatment for acne vulgaris

Poster presentatio

Fleas of fleas: The potential role of bacteriophages in Salmonella diversity and pathogenicity.

Non-typhoidal salmonellosis is an important foodborne and zoonotic infection, that causes significant global public health concern. Diverse serovars are multidrug-resistant and encode several virulence indicators, however, little is known on the role prophages play in driving these characteristics. Here, we extracted prophages from 75 Salmonella genomes, which represent the 15 most important serovars in the United Kingdom. We analysed the genomes of the intact prophages for the presence of virulence factors which were associated with; diversity, evolution and pathogenicity of Salmonella and to establish their genomic relationships. We identified 615 prophage elements from the Salmonella genomes, from which 195 prophages are intact, 332 being incomplete while 88 are questionable. The average prophage carriage was found to be more prevalent in S. Heidelberg, S. Inverness and S. Newport (10.2-11.6 prophages/strain), compared to S. Infantis, S. Stanley, S. Typhimurium and S. Virchow (8.2-9 prophages/strain) and S. Agona, S. Braenderup, S. Bovismorbificans, S. Choleraesuis, S. Dublin, and S. Java (6-7.8 prophages/strain), and S. Javiana and S. Enteritidis (5.8 prophages/strain). Cumulatively, 2760 virulence factors were detected from the intact prophages and associated with cellular functionality being linked to effector delivery/secretion system (73%), adherence (22%), magnesium uptake (2.7%), resistance to antimicrobial peptides (0.94%), stress/survival (0.4%), exotoxins (0.32%) and antivirulence (0.18%). Close and distant clusters were formed among the prophage genomes suggesting different lineages and associations with bacteriophages of other Enterobacteriaceae. We show that diverse repertoire of Salmonella prophages are associated with numerous virulence factors, and may contribute to diversity, pathogenicity and success of specific serovars

Bacterial Response to Nanoparticles at the Molecular Level

University of Minnesota Ph.D. dissertation. May 2018. Major: Chemistry. Advisor: Christy Haynes. 1 computer file (PDF); xiv, 222 pages.Nanotechnology has been an emerging field due to the promising properties of engineered nanomaterials, materials with at least one dimension less than 100 nanometers. With increasing application of NPs, the risk of these novel materials to environment requires thorough investigation to prevent negative impacts. NPs have enormous variety due to combinations of chemical compositions, sizes, shapes, structures and surface modifications. Building predictive models that link NP properties to biological outcomes is the key to proactive safer NP design. High-throughput toxicity screening and investigating toxicity mechanisms are the common two strategies building towards predictive models of nanotoxicity. These two strategies work together: high-throughput assays facilitate preliminary screening of potentially toxic materials for further mechanistic studies to discover biomarkers and molecular pathways of interest, which will in turn be validated on multiple materials and organisms with high-throughput screening. My thesis work combines both strategies to develop high-throughput screening assays and mechanistic understanding at different molecular levels of how an environmental bacterium, Shewanella oneidensis MR-1, responds to various NP exposures. In this work, Chapter 1 reviews recent advances in analytical nanotoxicology and identifies four key areas that would further bring the field to its maturity. Chapter 2 represents a comprehensive mechanistic study on bacteria responding to TiO2 NPs with UVA illumination. Chapter 3 uses gene expression to explore molecular response among two organisms at different trophic levels to positively and negatively charged gold NPs. Chapter 4 identifies that purification method can be one neglected source of apparent NP toxicity. A high-throughput bacterial viability assay that is free of NP interference is presented in Chapter 5. Finally, in Chapter 6, DNA damage is revealed as a toxicity mechanism for nanoscale complex metal oxide nanomaterials to bacteria

Green Chemistry, Green Engineering and Eco-Innovation Towards a More Sustainable Petrochemical Industry: Determinants of Brazilian Petrochemical Companies´ Engagement in GCE-Based Eco-Innovation Processes

__Abstract__ It is the general wisdom, within the petrochemical industrial sector, that technological changes, for the development of cleaner products, processes and services, is a basic requirement for companies to achieve advanced states of environmental and economic sustainability in the 21st century. It is also agreed that to innovate is essential for this industry make the necessary advancements and to reconcile the firms´ interests of being profitable, in the short-term, with their long-term capacity to evolve with societal pressures to ensure worker‘s and consumer‘s health within a sustainable biosphere. Despite these corporate perspectives, companies´ decisions to engage in the process of change, through technological and management innovations, is contingent on a series of elements that determine companies‘ eco-innovative behavior. This thesis was designed to gain insight into the aspects and determinants that influence ecoinnovative behavior of companies in the Brazilian petrochemical sector. Drawing on Icel Ajzen´s Theory of Planned Behavior (TPB), on Montalvo Corral´s TPB-based structural descriptive innovation-directed behavioral model and on Franco Malerba´s Sectoral Systems of Innovation (SSI) framework as its major theoretical frameworks, this study was designed to obtain answers to these research questions: - What is the extent to which Brazilian petrochemical companies are willing to innovate based upon the Twelve Principles of the Green Chemistry and the Twelve Principles of Green Engineering (GCE) as approaches to more sustainable behavior? - How can their willingness to change be documented and explained and what are its main determinants? -What are the sector´s main agents, mechanisms and actions, which are integral to its implementation of GCE and to going beyond them in the future