Temperature control in transport delay systems

A control architecture is proposed for temperature control in manufacturing applications based on the internal model principle. It is applied to a problem where the material exit temperature is to be controlled by changing the transportation speed to influence the amount of heat loss. The internal model is used to achieve a fast response with minimal overshoot. The controller tuning is carried out using constraints on the sensitivity function to map out the controller parameter region to achieve this performance. The robustness of the controller to parametric uncertainty is also considered. Results are shown from the application of this controller to the temperature controller for a hot strip rolling mill

Improving Photoelectron Counting and Particle Identification in Scintillation Detectors with Bayesian Techniques

Many current and future dark matter and neutrino detectors are designed to measure scintillation light with a large array of photomultiplier tubes (PMTs). The energy resolution and particle identification capabilities of these detectors depend in part on the ability to accurately identify individual photoelectrons in PMT waveforms despite large variability in pulse amplitudes and pulse pileup. We describe a Bayesian technique that can identify the times of individual photoelectrons in a sampled PMT waveform without deconvolution, even when pileup is present. To demonstrate the technique, we apply it to the general problem of particle identification in single-phase liquid argon dark matter detectors. Using the output of the Bayesian photoelectron counting algorithm described in this paper, we construct several test statistics for rejection of backgrounds for dark matter searches in argon. Compared to simpler methods based on either observed charge or peak finding, the photoelectron counting technique improves both energy resolution and particle identification of low energy events in calibration data from the DEAP-1 detector and simulation of the larger MiniCLEAN dark matter detector.Comment: 16 pages, 16 figure

Radon backgrounds in the DEAP-1 liquid-argon-based Dark Matter detector

The DEAP-1 \SI{7}{kg} single phase liquid argon scintillation detector was operated underground at SNOLAB in order to test the techniques and measure the backgrounds inherent to single phase detection, in support of the \mbox{DEAP-3600} Dark Matter detector. Backgrounds in DEAP are controlled through material selection, construction techniques, pulse shape discrimination and event reconstruction. This report details the analysis of background events observed in three iterations of the DEAP-1 detector, and the measures taken to reduce them. The $^{222}$Rn decay rate in the liquid argon was measured to be between 16 and \SI{26}{\micro\becquerel\per\kilogram}. We found that the background spectrum near the region of interest for Dark Matter detection in the DEAP-1 detector can be described considering events from three sources: radon daughters decaying on the surface of the active volume, the expected rate of electromagnetic events misidentified as nuclear recoils due to inefficiencies in the pulse shape discrimination, and leakage of events from outside the fiducial volume due to imperfect position reconstruction. These backgrounds statistically account for all observed events, and they will be strongly reduced in the DEAP-3600 detector due to its higher light yield and simpler geometry

In-situ characterization of the Hamamatsu R5912-HQE photomultiplier tubes used in the DEAP-3600 experiment

The Hamamatsu R5912-HQE photomultiplier-tube (PMT) is a novel high-quantum efficiency PMT. It is currently used in the DEAP-3600 dark matter detector and is of significant interest for future dark matter and neutrino experiments where high signal yields are needed. We report on the methods developed for in-situ characterization and monitoring of DEAP's 255 R5912-HQE PMTs. This includes a detailed discussion of typical measured single-photoelectron charge distributions, correlated noise (afterpulsing), dark noise, double, and late pulsing characteristics. The characterization is performed during the detector commissioning phase using laser light injected through a light diffusing sphere and during normal detector operation using LED light injected through optical fibres

Rhetoric and reality: Critical perspective on education in a 3D virtual world

The emergence of any new educational technology is often accompanied by inflated expectations about its potential for transforming pedagogical practice and improving student learning outcomes. A critique of the rhetoric accompanying the evolution of 3D virtual world education reveals a similar pattern, with the initial hype based more on rhetoric than research demonstrating the extent to which rhetoric matches reality. Addressed are the perceived gaps in the literature through a critique of the rhetoric evident throughout the evolution of the application of virtual worlds in education and the reality based on the reported experiences of experts in the field of educational technology, who are all members of the Australian and New Zealand Virtual Worlds Working Group. The experiences reported highlight a range of effective virtual world collaborative and communicative teaching experiences conducted in members’ institutions. Perspectives vary from those whose reality is the actuation of the initial rhetoric in the early years of virtual world education, to those whose reality is fraught with challenges that belie the rhetoric. Although there are concerns over institutional resistance, restrictions, and outdated processes on the one-hand, and excitement over the rapid emergence of innovation on the other, the prevailing reality seems to be that virtual world education is both persistent and sustainable. Explored are critical perspectives on the rhetoric and reality on the educational uptake and use of virtual worlds in higher education, providing an overview of the current and future directions for learning in virtual worlds

Rhetoric and reality: Critical perspective on education in a 3D virtual world

The emergence of any new educational technology is often accompanied by inflated expectations about its potential for transforming pedagogical practice and improving student learning outcomes. A critique of the rhetoric accompanying the evolution of 3D virtual world education reveals a similar pattern, with the initial hype based more on rhetoric than research demonstrating the extent to which rhetoric matches reality. Addressed are the perceived gaps in the literature through a critique of the rhetoric evident throughout the evolution of the application of virtual worlds in education and the reality based on the reported experiences of experts in the field of educational technology, who are all members of the Australian and New Zealand Virtual Worlds Working Group. The experiences reported highlight a range of effective virtual world collaborative and communicative teaching experiences conducted in members’ institutions. Perspectives vary from those whose reality is the actuation of the initial rhetoric in the early years of virtual world education, to those whose reality is fraught with challenges that belie the rhetoric. Although there are concerns over institutional resistance, restrictions, and outdated processes on the one-hand, and excitement over the rapid emergence of innovation on the other, the prevailing reality seems to be that virtual world education is both persistent and sustainable. Explored are critical perspectives on the rhetoric and reality on the educational uptake and use of virtual worlds in higher education, providing an overview of the current and future directions for learning in virtual worlds

Risk assessment and decision making about in-labour transfer from rural maternity care: a social judgment and signal detection analysis

Background: The importance of respecting women's wishes to give birth close to their local community is supported by policy in many developed countries. However, persistent concerns about the quality and safety of maternity care in rural communities have been expressed. Safe childbirth in rural communities depends on good risk assessment and decision making as to whether and when the transfer of a woman in labour to an obstetric led unit is required. This is a difficult decision. Wide variation in transfer rates between rural maternity units have been reported suggesting different decision making criteria may be involved; furthermore, rural midwives and family doctors report feeling isolated in making these decisions and that staff in urban centres do not understand the difficulties they face. In order to develop more evidence based decision making strategies greater understanding of the way in which maternity care providers currently make decisions is required. This study aimed to examine how midwives working in urban and rural settings and obstetricians make intrapartum transfer decisions, and describe sources of variation in decision making. Methods: The study was conducted in three stages. 1. 20 midwives and four obstetricians described factors influencing transfer decisions. 2. Vignettes depicting an intrapartum scenario were developed based on stage one data. 3. Vignettes were presented to 122 midwives and 12 obstetricians who were asked to assess the level of risk in each case and decide whether to transfer or not. Social judgment analysis was used to identify the factors and factor weights used in assessment. Signal detection analysis was used to identify participants' ability to distinguish high and low risk cases and personal decision thresholds. Results: When reviewing the same case information in vignettes midwives in different settings and obstetricians made very similar risk assessments. Despite this, a wide range of transfer decisions were still made, suggesting that the main source of variation in decision making and transfer rates is not in the assessment but the personal decision thresholds of clinicians. Conclusions: Currently health care practice focuses on supporting or improving decision making through skills training and clinical guidelines. However, these methods alone are unlikely to be effective in improving consistency of decision making

Electromagnetic backgrounds and potassium-42 activity in the DEAP-3600 dark matter detector

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