3,594 research outputs found

    Numerical study of concrete-filled austenitic stainless steel CHS stub columns with high-strength steel inner tubes

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    [EN] A numerical modelling programme simulating the structural behaviour of concrete-filled double skin tubular (CFDST) stub columns with stainless steel outer tubes and high strength steel inner tubes is presented in this paper. The numerical model, which was developed using the finite element package ABAQUS, was initially validated against existing experimental results considering ultimate load, load-deflection histories and failure modes, with good agreement observed. Upon validation of the FE model, an extensive parametric study was undertaken whereby the cross-section slendernesses of the outer and inner tubes, the strength of the inner tube and the concrete grades were varied. These generated results together with the experimental data were then employed to assess the suitability of the design provisions of the European Standard EN 1994-1-1 and American Specification for concrete-filled tubes. Modifications to these design rules are also proposed, and a reduction factor (Ρ) is suggested to account for the effective compressive strength in high strength concrete.Wang, F.; Young, B.; Gardner, L. (2018). Numerical study of concrete-filled austenitic stainless steel CHS stub columns with high-strength steel inner tubes. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 343-350. https://doi.org/10.4995/ASCCS2018.2018.8273OCS34335

    Planning Border Controls at UK Airports: Quantitative studies into operational decisions and their impact on passengers

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    This thesis contains three new research projects in the field of airport border control. Utilising unique access to the UK Home Office and Border Force, these studies combine current and historic data of airport border control scenarios with advanced quantitative methods to provide novel analysis of passenger delays and their costs. This analysis is framed in terms of the significant rise in global air passenger numbers in recent decades and the major technological, operational and information changes that have occurred in response. The overall aim has been to consider areas where these new forms of airport border controls may continue to be operating in ways that result in suboptimal outcomes for passengers; in terms of both average wait times and the frequency of ‘unacceptably’ long delays. Whilst there is a vast literature exploring this field in terms of the theoretical impact of new systems of border control, there are few that explore the objectives of operational decisions or provide empirical evidence to evaluate their underlying logic. I attempt to rectify this by exploring three specific elements of the border system, using UK airports as a case study. The first project considers the impact that the stochasticity of flight arrival times has on the risks that long wait times will occur at non-automated border controls. Whilst authorities receive prior information on the number of flights, passengers, and passenger type, it cannot predict exactly what time those flights will arrive. Using stochastic Discrete Event Simulation (DES) of a UK airport terminal, we identify the wide range of border delays that occur from this single variable and suggest the staffing decisions that would be necessary to ameliorate this risk. My second project explores the costs of variances in border processing times by nationality. Using the results of observational research at various UK ports, I establish the average times that different nationalities spend at staffed desks. These are then included in an updated version of our DES model to show the link between processing rates and border delays. Further analysis illustrates the savings that could be achieved from ‘levelling down’ processing times for nationalities facing the highest challenge to their border. The final project switches to analysing newer automated border controls (eGates). Using results from a stated preference survey, I challenge existing valuations of travel time suggested for passengers in these systems and provide new insight into how the full arrival process needs to be considered when costing delays. DES modelling of multiple UK airports is then used to provide examples of how both time and operational costs vary as the level of eGate provision changes. I conclude from these results that the passenger time costs of an undersupply of gates will often significantly exceed the redundant operational costs of an oversupply

    The Epoch of Disk Formation: z is Approximately l to Today

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    We present data on galaxy kinematics, morphologies, and star-formation rates over 0.1 less than z less than 1.2 for approximately 500 blue galaxies. These data show how systems like our own Milky-Way have come into being. At redshifts around 1, about half the age of the Universe ago, Milky-Way mass galaxies were different beasts than today. They had a significant amount of disturbed motions, disturbed morphologies, shallower potential wells, higher specific star-formation rates, and likely higher gas fractions. Since redshift approximately 1, galaxies have decreased in disturbed motions, increased in rotation velocity and potential well depth, become more well-ordered morphologically, and decreased in specific star-formation rate. We find interrelationships between these measurements. Galaxy kinematics are correlated with morphology and specific star-formation rate such that galaxies with the fastest rotation velocities and the least amounts of disturbed motions have the most well-ordered morphologies and the lowest specific star-formation rates. The converse is true. Moreover, we find that the rate at which galaxies become more well-ordered kinematically (i.e., increased rotation velocity, decreased disturbed motions) and morphologically is directly proportional to their stellar mass

    An outbreak of Bacillus cereus toxin-mediated emetic and diarrhoeal syndromes at a restaurant in Canberra, Australia 2018

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    A cluster of gastrointestinal illness was detected following receipt of a complaint of becoming ill after a multi-course dinner at a restaurant in Canberra, Australian Capital Territory (ACT), Australia. The complaint led to an investigation by ACT Health. Food samples retained by the restaurant for microbiological analysis returned an unsatisfactory level of Bacillus cereus in beef (19,000 colony forming units/gram [cfu/g]) and a satisfactory level in arancini (50 cfu/g). These positive samples underwent whole genome sequencing and genes encoding diarrhoeal toxins were detected with no laboratory evidence of the emetic toxin. No stool specimens were collected. A cohort study was undertaken and 80% (33/41) of patrons took part in a structured interview. There was no significant difference in age or sex between those ill and not ill. Due to universal exposure most foods were unable to be statistically analysed and no significant results were found from the food history. The ill cohort diverged into two distinct groups based on incubation period and symptoms suggesting this outbreak involved B. cereus intoxication with both diarrhoeal and potentially emetic toxins. Some hygiene practices during food preparation were noted to be inadequate and heating and cooling procedures were unverified when questioned. A combination of the incubation periods and symptom profile, food laboratory evidence, and genomic sequencing of the B. cereus diarrhoeal gene suggest a probable aetiology of B. cereus intoxication. Public health action included the restaurant rectifying hygiene practices and documenting heating/cooling procedures

    Music of 18 Performances: Evaluating Apps and Agents with Free Improvisation

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    We present a study where a small group of experienced iPad musicians evaluated a system of three musical touch-screen apps and two server-based agents over 18 controlled improvisations. The performers’ perspectives were recorded through surveys, interviews, and interaction data. Our agent classifies the touch gestures of the performers and identifies new sections in the improvisations while a control agent returns similar messages sourced from a statistical model. The three touch-screen apps respond according to design paradigms of reward, support, and disruption. In this study of an ongoing musical practice, significant effects were observed due to the apps’ interfaces and how they respond to agent interactions. The “reward” app received the highest ratings. The results were used to iterate the app designs for later performances

    Cortisol and cognitive function in midlife: the role of childhood cognition and educational attainment

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    Adult cognition and age-related cognitive decline can be influenced by dysregulation of the hypothalamic pituitary adrenal axis with concomitant changes in cortisol levels. However, very little is known about the role of childhood cognition and educational attainment in this relationship. Using data from the British 1946 birth cohort, the present study investigated: (1) associations between cortisol levels and patterns and cognitive function in midlife; (2) direct and interactive effects of childhood cognition, educational attainment and cortisol on cognitive function in midlife. Verbal memory, letter search speed and reaction time were assessed at age 60-64 years. Salivary cortisol samples (wakening, 30 min after wakening and evening) were collected at the same age. Childhood cognitive ability was measured at ages 8, 11, and 15, and educational level was reported at age 26. Associations between cortisol, childhood cognition, educational attainment and cognitive function in midlife were tested using linear regression and structural equation modelling approaches. Higher evening cortisol level was associated with slower reaction time and lower verbal memory. These associations were independent of childhood cognition and education as well as a range of other potential confounders. Childhood cognition and education were not directly associated with evening cortisol. However, there was a significant interaction effect between childhood cognition and evening cortisol on reaction time (p=.002): higher evening cortisol was associated with slower reaction time only among those with low childhood cognitive ability. There was little evidence of associations between the other cortisol measures and cognitive function
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