An evaluation of weld metal nitrogen retention and properties in 316NL austenitic stainless steel

A series of tests were conducted using varying levels of nitrogen and helium in a conventional argon shielding gas when welding 316LN austenitic stainless steel. The outcome was that a 15 per cent nitrogen addition to the argon shielding gas had the most significant effect on increasing the weld metal nitrogen. Subsequent additions of helium to the argon 15 per cent nitrogen shielding gas had very little overall benefit. Increasing the nitrogen content of the weld metal had the consequential effects of decreasing the ferrite content and the hardness. As a result of solid solution strengthening, the yield strength increased with increase in nitrogen content. There was an increase in impact toughness as the nitrogen content increased. This was related to the decreased ferrite content associated with the strong austenetizing potential of nitrogen. It was also shown that an almost fully austenitic weld metal could still have very good toughness. In combination with these effects there was no loss in corrosion resistance. The addition of nitrogen to a conventional argon shielding gas presents attractive cost and quality benefits over the established requirement to over alloy the weld filler material with expensive alloys such as nickel

Soluble trace metals in aerosols over the tropical south-east Pacific offshore of Peru

Bulk aerosol samples collected during cruise M91 of FS Meteor off the coast of Peru in December 2012 were analysed for their soluble trace metal (Fe, Al, Mn, Ti, Zn, V, Ni, Cu, Co, Cd, Pb, Th) and major ion (including NO3- and NH4+) content. These data are among the first recorded for trace metals in this relatively poorly studied region of the global marine atmosphere. To the north of ~13°S, the concentrations of several elements (Fe, Ti, Zn, V, Ni, Pb) appear to be related to distance from the coast. At the south of the transect (~15-16°S), elevated concentrations of Fe, Cu, Co and Ni were observed, and we calculated dry deposition fluxes of soluble Cu approximately an order of magnitude higher than a recent model-based estimate of total Cu deposition to the region. The model did not take account of emissions from the large smelting facilities in the south of Peru and northern Chile and our results may indicate that these facilities constitute an important source of trace metals to the region. Calculated dry deposition fluxes (3370-17800 and 16-107 nmol m-2 d-1 for inorganic nitrogen and soluble Fe respectively) indicated that atmospheric input to the waters of the Peru upwelling system contains an excess of Fe over N, with respect to phytoplankton requirements. This may be significant as primary production in these waters has been reported to be limited by Fe availability, but atmospheric deposition is unlikely to be the dominant source of Fe to the system

Hyperfine splitting in positronium to O(α7me){\cal O}(\alpha^7m_e): one-photon annihilation contribution

We present the complete result for the ${\cal O}(\alpha^7m_e)$ one-photon annihilation contribution to the hyperfine splitting of the ground state energy levels in positronium. Numerically it increases the prediction of quantum electrodynamics by $217\pm 1$ kHz.Comment: 5 pages, 2 figure

Polymer-stabilized sialylated nanoparticles : synthesis, optimization, and differential binding to influenza hemagglutinins

During influenza infection, hemagglutinins (HAs) on the viral surface bind to sialic acids on the host cell's surface. While all HAs bind sialic acids, human influenza targets terminal α2,6 sialic acids and avian influenza targets α2,3 sialic acids. For interspecies transmission (zoonosis), HA must mutate to adapt to these differences. Here, multivalent gold nanoparticles bearing either α2,6- or α2,3-sialyllactosamine have been developed to interrogate a panel of HAs from pathogenic human, low pathogenic avian, and other species' influenza. This method exploits the benefits of multivalent glycan presentation compared to monovalent presentation to increase affinity and investigate how multivalency affects selectivity. Using a library-orientated approach, parameters including polymer coating and core diameter were optimized for maximal binding and specificity were probed using galactosylated particles and a panel of biophysical techniques [ultraviolet-visible spectroscopy, dynamic light scattering, and biolayer interferometry]. The optimized particles were then functionalized with sialyllactosamine and their binding analyzed against a panel of HAs derived from pathogenic influenza strains including low pathogenic avian strains. This showed significant specificity crossover, which is not observed in monovalent formats, with binding of avian HAs to human sialic acids and in agreement with alternate assay formats. These results demonstrate that precise multivalent presentation is essential to dissect the interactions of HAs and may aid the discovery of tools for disease and zoonosis transmission

Observer Incorporated Neoclassical Controller Design: A Discrete Perspective

Control theory has generally been divided into two categories, modern control and classical control. Modern control uses state feedback to alter the pole locations of a given system. Classical control uses pre-compensation to alter the zeroes of the system and uses output feedback to adjust the poles to bring stability to the system. The drawback is that the application of classical control techniques can be a lengthy, complicated and iterative design process and in the end, classical control techniques still do not give information about the state of the system. Neoclassical control combines classical control techniques with the state feedback approach of modern control to stabilize the system, eliminate the steady state error, provide relevant internal state information, and reduce the time it takes to design the controller. This thesis explores the application of neoclassical control to discrete-time systems. The mass-spring-damper, magnetic levitation, and ball and beam systems are discretized using the zero-order-hold or the Euler approximation. State-feedback control is used to modify the pole locations for these systems. A discrete-time integrator is put in series to eliminate the steady-state error for a step input. The pre-compensator is also put in series to replace the numerator of the open-loop system with a desired numerator. The unit output-feedback is then used to close the loop. The closed-loop system will have a step response which matches the discrete-time optimal ITAE, Bessel, or Butterworth transfer functions. An observer is added to estimate the state of the plant in this work. The observer is applied to the discrete-time mass-spring-damper, the magnetic levitation, and the ball and beam systems in such a way that the error in the state estimate will be driven to zero within the desired period of time. This will allow the application of this controller to systems when the state is not known or measurable

The machinery of eviction : bailiffs, power, resistance and eviction enforcement practices in England and Wales

PhD ThesisThis thesis addresses a significant research gap in critical research on forced eviction. It attempts to shift focus from the experiences of the evicted, examined in previous studies, to the work of evictors and eviction enforcement. It asks how the ‘tools, technologies, strategies, and tactics’ of forced eviction develop and are implemented in England and Wales. Using qualitative interviews centred around a case study of a city in the North of England to examine the ‘everyday’ form of evictions, this thesis looks at the work of a Rent Arrears Recovery Team on the ‘Benford’ housing estate in the city, and the working lives of County Court Bailiffs at the local court as they work in the context of a national ‘housing crisis’. Interviews with third party organizations and a High Court Enforcement firm, video footage, and online accounts of large-scale evictions provided by a wide range of sources from social movements are used to explore the ‘exceptional’ forms of displacement that emerge on a national scale. This research shows that Eviction enforcement actors and specialists have to employ forms of coercion which exist on a continuum between the ‘emotional’ and the ‘physical’; these practices are underpinned by ‘intuitive’ tactics built through individual and personal histories and the historical context in which evictions take place. These strategies and tactics of eviction are shaped by the resistance of the evicted, and the development of the disciplinary institutions of eviction happens in response to this resistance, which sets the pace for the development of the capacity of the state and economy to displace. This points to a need for more work critiquing the disciplinary institutions of forced eviction, and the global economy of eviction enforcement

Lagrangian modelling of precipitation and speleothem proxy oxygen isotope systematics in the East Asian Summer Monsoon region

The Asian Summer Monsoon generates intense seasonal precipitation across India, China and Indochina, comprising Earth’s largest monsoonal climate regime, and this vital component of the global energy and water cycles directly impacts the world’s most populous regions. Accurate palaeomonsoon reconstructions are required to investigate natural climate variability beyond the coverage of instrumental records and inform predictions of future monsoon trends. Stable oxygen isotope ratios (δ18O) are an important proxy for hydroclimate variability and stalagmite δ18O is widely used to investigate East Asian palaeoclimate, typically interpreted as a semi-quantitative measure of precipitation amount. However, recent studies suggest δ18O instead reflects multiple hydroclimatic processes, warranting a detailed understanding of precipitation and proxy δ18O systematics. This thesis (i) presents a quantitative Lagrangian study of atmospheric moisture transport and precipitation across central and eastern China, a continental region affected by the East Asian Summer Monsoon (EASM); (ii) investigates the hydroclimatic drivers of precipitation δ18O variability at Wanxiang Cave, an important site for palaeomonsoon reconstruction located near to the northerly EASM limit; (iii) evaluates the extent to which seasonal- to decadal-scale proxy δ18O variability reflects terrestrial moisture fluxes by constructing a pseudoproxy record for Wanxiang. Present-day precipitation across monsoonal China is primarily derived from the northern Indian Ocean and recycled intensely over the East Asian continent; Pacific Ocean moisture export peaks during winter. A geographically variable isotopic source effect is apparent in present-day mean monthly precipitation δ18O data. Wanxiang Cave precipitation δ18O variability during AD 2001-2002 is successfully reproduced by a recently-developed Lagrangian model which simulates air masses’ isotopic evolution along three-dimensional atmospheric trajectories, though winter values are ~2 ‰ over-depleted. Contributions of Tibetan Plateau- and free troposphere-derived moisture are identified as synoptic-scale isotopic depletion processes. Overall, land-derived moisture causes isotopic enrichment during summer, thus moderating depletion due to strengthened EASM circulation or increased precipitation amount. As such, periods of elevated summer surface temperatures may attenuate the seasonal EASM signal in precipitation and proxy δ18O. An idealised Rayleigh-type isotope model is unable to capture these effects accurately, emphasising the importance of regional moisture fluxes. A pseudoproxy record, driven by terrestrial moisture fluxes, replicates seasonal- to decadal-scale stalagmite δ18O variability at Wanxiang. The work presented in this thesis offers new insights into the influence of atmospheric moisture transport dynamics on precipitation and proxy δ18O variability across central and eastern China. This constitutes an important advancement in our ability to use δ18O to reconstruct past climate variability quantitatively in the EASM region

Kinematics and Preliminary FEMA P-695 Evaluation of the NewZ-BREAKSS Steel Boundary Frame with Buckling Restrained Brace Structural Fuses

Buckling Restrained Braced Frames (BRBFs) have become a popular seismic force resisting system (SFRS) due to their high ductility and energy dissipation. However, BRBFs are also susceptible to large residual drifts, which can make repair difficult. Efforts to reduce the residual drift of BRBFs typically involve special self-centering braces, or by using a dual system in tandem with the BRBF. This study proposes an alternative approach, in which a self-centering steel rocking frame is used as the boundary frame for the BRBF. The proposed system, called the NewZ-BREAKSS Buckling Restrained Braced Frame (NZ-BRBF) utilizes the recently proposed NewZ-BREAKSS (NZ) boundary frame to increase the post-yield stiffness of the system while concentrating all damage to the BRBs. The NZ-BRBF system is expected to behave similarly to conventional BRBF, but with smaller residual drifts and a boundary frame that remains essentially elastic, simplifying repair. This study presents a numerical investigation of the proposed low-damage SFRS, using the FEMA P-695 methodology as a guiding framework. The results suggest that the NZ-BRBF can exhibit better performance than conventional BRBFs and can be designed with the same response modification factor (R factor) as conventional BRBFs

Influence of collection substrate and extraction method on the speciation of soluble iodine in atmospheric aerosols

The extraction into aqueous solution of total soluble iodine (TSI), iodide and iodate were examined as a function of extraction times between 5 and 60 min for two different extraction methods and from two types of commonly used aerosol collection substrates. The extraction methods tested were ultrasonic agitation and mechanical shaking, while the substrates were cellulose fibre (CF) and glass fibre (GF). Tests were carried on substrates spiked with known amounts of iodide and iodate and on a pair of ambient aerosol samples collected at the University of East Anglia on both substrates over the same time period. The combination of ultrasonic agitation and CF substrates (which has been used in many published studies of aerosol iodine speciation) was shown to lead to variable recovery of iodine species and changes in speciation over extraction time. Mechanical shaking of GF substrates gave good recoveries of iodide and iodate from spiked experiments and stable speciation with time for the ambient aerosol sample. This combination is recommended for future use in the determination of aerosol iodine speciation. Mechanical shaking also appeared to be preferable to ultrasonic agitation for samples that were collected on CF substrates. The optimised conditions (mechanical shaking of GF substrates for 30 min) were applied to the analysis of samples collected during the Stratospheric ozone: Halogen Impacts in a Varying Atmosphere (SHIVA) cruise in the South China and Sulu Seas in November 2011. The results obtained showed variable proportions of iodide, iodate and soluble organic iodine species in these samples, with iodide concentrations possibly related to airmass history and background chemistry