Introduction: Psychoanalysis and the photographer

The following text is based on the introduction to a symposium on “Psychoanalysis and the Photographer”, held at the University of Westminster in Marylebone, London, UK. (The symposium was organized by David Bate and took place on the 25 October 2014. Speakers included Vincent Dachy, Sharon Kivland, Darian Leader, Patricia Townsend and Mariah Walsh.) The text sets out a general position on the reasons for organizing the event, but more importantly is included here as a contextual paper, to situate questions about the use of psychoanalysis in relation to photography theory. The event and the aim of this text here is to consider whether a dialogue with psychoanalytic theory can offer any insight into contemporary questions about photography.     

A survey of scheduling metrics and an improved ordering policy for list schedulers operating on workloads with dependencies and a wide variation in execution times

This paper considers the dynamic scheduling of parallel, dependent tasks onto a static, distributed computing platform, with the intention of delivering fairness and quality of service (QoS) to users. The key QoS requirement is that responsiveness is maintained for workloads with a wide range of execution times (minutes to months) even under transient periods of overload. A survey of schedule QoS metrics is presented, classified into those dealing with responsiveness, fairness and utilisation. These metrics are evaluated as to their ability to detect undesirable features of schedules. The Schedule Length Ratio (SLR) metric is shown to be the most helpful for measuring responsiveness in the presence of dependencies. A novel list scheduling policy called Projected-SLR is presented that delivers good responsiveness and fairness by using the SLR metric in its scheduling decisions. Projected-SLR is found to perform equally as well in responsiveness, fairness and utilisation as the best of the other scheduling policies evaluated (Shortest Remaining Time First/SRTF), using synthetic workloads and an industrial trace. However, Projected-SLR does this with a guarantee of starvation-free behaviour, unlike SRTF.     

Finite element analysis of a single bead-on-plate specimen using SYSWELD

An uncoupled thermal and mechanical analysis has been carried out using the software code, SYSWELD in order to model a single bead-on-plate specimen. The heat source is represented by the Goldak double ellipsoid model which is available within the code. The parameters of this model were defined by the welding parameters and the macrographs and thermocouple data provided in the benchmark. The mechanical analysis is based on an isotropic hardening model which is defined by the tensile data provided in the protocol. Annealing is assumed at a temperature of 1400 °C. This paper describes the heat source fitting, the subsequent thermal and mechanical analyses and presents selected results.     

Strain path change effects in the local necking of aluminum sheet and in the tension of internally pressurized tubes

It is possible to increase significantly the uniform elongation achieved in the uniaxial tension of commercial purity aluminum by accelerating the testing rate. This effect is linked to a significant rate sensitivity of strain hardening. However, very little increase in the strains associated with the final stages of localization in sheet specimens were achieved by this means. The importance of the change in strain rate and path on local necking has been investigated by introducing path changes of appropriate magnitudes in tubular tensile specimens by internal pressurization. The path change led to a decrease in strain-hardening rate which was not compensated for by an increase in strain rate. The potential consequences of this effect upon ductility in sheets are significant and limit the potential usefulness of any rate sensitivity of strain hardening in increasing formability.     

The effects of combined strain-path and strain-rate changes in aluminum

The effect of changes in both the direction of tensile stress and the strain rate upon the plastic behavior and microstructure of aluminum has been investigated. The reduction in strain-hardening rate following a strain-path change was influenced by the strain rate prior to and after the change; higher strain rates in the first stage and lower rates in the second stage decreased the initial transient hardening rate. The introduction of a large path change significantly reduced the effect of strain-rate changes on the strain-hardening rate observed in testing without changing the tensile axis. Evidence of cell wall disruption following a path change was found, and this mechanism combined with effects of cell wall orientation can qualitatively explain the removal of the rate sensitivity of hardening rate because the usual recovery events in cell walls no longer have a dominant influence on flow stress development.     

The effects of combined strain-path and strain-rate changes in aluminum

The effect of changes in both the direction of tensile stress and the strain rate upon the plastic behavior and microstructure of aluminum has been investigated. The reduction in strain-hardening rate following a strain-path change was influenced by the strain rate prior to and after the change; higher strain rates in the first stage and lower rates in the second stage decreased the initial transient hardening rate. The introduction of a large path change significantly reduced the effect of strain-rate changes on the strain-hardening rate observed in testing without changing the tensile axis. Evidence of cell wall disruption following a path change was found, and this mechanism combined with effects of cell wall orientation can qualitatively explain the removal of the rate sensitivity of hardening rate because the usual recovery events in cell walls no longer have a dominant influence on flow stress development.