Comprehensive Characterization of Measurement Data Gathered by the Pressure Tube to Calandria Tube Gap Probe

Multi-frequency eddy current measurements are employed in estimating pressure tube (PT) to calandria tube (CT) gap in CANDU fuel channels, a critical inspection activity required to ensure fitness for service of fuel channels. In this thesis, a comprehensive characterization of eddy current gap data is laid out, in order to extract further information on fuel channel condition, and to identify generalized applications for multi-frequency eddy current data. A surface profiling technique, generalizable to multiple probe and conductive material configurations has been developed. This technique has allowed for identification of various pressure tube artefacts, has been independently validated (using ultrasonic measurements), and has been deployed and commissioned at Ontario Power Generation. Dodd and Deeds solutions to the electromagnetic boundary value problem associated with the PT to CT gap probe configuration were experimentally validated for amplitude response to changes in gap. Using the validated Dodd and Deeds solutions, principal components analysis (PCA) has been employed to identify independence and redundancies in multi-frequency eddy current data. This has allowed for an enhanced visualization of factors affecting gap measurement. Results of the PCA of simulation data are consistent with the skin depth equation, and are validated against PCA of physical experiments. Finally, compressed data acquisition has been realized, allowing faster data acquisition for multi-frequency eddy current systems with hardware limitations, and is generalizable to other applications where real time acquisition of large data sets is prohibitive.

Formation of helical ion chains

We study the nonequilibrium dynamics of the linear to zigzag structural phase transition exhibited by an ion chain confined in a trap with periodic boundary conditions. The transition is driven by reducing the transverse confinement at a finite quench rate, which can be accurately controlled. This results in the formation of zigzag domains oriented along different transverse planes. The twists between different domains can be stabilized by the topology of the trap and under laser cooling the system has a chance to relax to a helical chain with nonzero winding number. Molecular dynamics simulations are used to obtain a large sample of possible trajectories for different quench rates. The scaling of the average winding number with different quench rates is compared to the prediction of the Kibble-Zurek theory, and a good quantitative agreement is found.

In-situ formation of solidified hydrogen thin-membrane targets using a pulse tube cryocooler

An account is given of the Central Laser Facility's work to produce a cryogenic hydrogen targetry system using a pulse tube cryocooler. Due to the increasing demand for low Z thin laser targets, CLF (in collaboration with TUD) have been developing a system which allows the production of solid hydrogen membranes by engineering a design which can achieve this remotely; enabling the gas injection, condensation and solidification of hydrogen without compromising the vacuum of the target chamber. A dynamic sealing mechanism was integrated which allows targets to be grown and then remotely exposed to open vacuum for laser interaction. Further research was conducted on the survivability of the cryogenic targets which concluded that a warm gas effect causes temperature spiking when exposing the solidified hydrogen to the outer vacuum. This effect was shown to be mitigated by improving the pumping capacity of the environment and reducing the minimum temperature obtainable on the target mount. This was achieved by developing a two-stage radiation shield encased with superinsulating blanketing; reducing the base temperature from 14 0.5 K to 7.2 0.2 K about the coldhead as well as improving temperature control stability following the installation of a high-performance temperature controller and sensor apparatus. The system was delivered experimentally and in July 2014 the first laser shots were taken upon hydrogen targets in the Vulcan TAP facility.

Settlement Duration and Materiality:Formal Chronological Models for the Development of Barnhouse, a Grooved Ware Settlement in Orkney

Radiocarbon dating and Bayesian chronological modelling, undertaken as part of the investigation by the Times of Their Lives project into the development of Late Neolithic settlement and pottery in Orkney, has provided precise new dating for the Grooved Ware settlement of Barnhouse, excavated in 1985–91. Previous understandings of the site and its pottery are presented. A Bayesian model based on 70 measurements on 62 samples (of which 50 samples are thought to date accurately the deposits from which they were recovered) suggests that the settlement probably began in the later 32nd century cal bc (with Houses 2, 9, 3 and perhaps 5a), possibly as a planned foundation. Structure 8 – a large, monumental structure that differs in character from the houses – was probably built just after the turn of the millennium. Varied house durations and replacements are estimated. House 2 went out of use before the end of the settlement, and Structure 8 was probably the last element to be abandoned, probably during the earlier 29th century cal bc. The Grooved Ware pottery from the site is characterised by small, medium-sized, and large vessels with incised and impressed decoration, including a distinctive, false-relief, wavy-line cordon motif. A considerable degree of consistency is apparent in many aspects of ceramic design and manufacture over the use-life of the settlement, the principal change being the appearance, from c. 3025–2975 cal bc, of large coarse ware vessels with uneven surfaces and thick applied cordons, and of the use of applied dimpled circular pellets. The circumstances of new foundation of settlement in the western part of Mainland are discussed, as well as the maintenance and character of the site. The pottery from the site is among the earliest Grooved Ware so far dated. Its wider connections are noted, as well as the significant implications for our understanding of the timing and circumstances of the emergence of Grooved Ware, and the role of material culture in social strategies.

Theoretical Performance Model and Initial Experimentation of a Baffled-Tube Ram Accelerator

Thesis (Master's)--University of Washington, 2016-08

Analyse numérique du changement de phase solide-liquide autour d'un tube horizontal soumis à une sollicitation thermique périodique

Ce mémoire présente un modèle mathématique et numérique pour analyser le comportement d’une unité de stockage thermique à changement de phase solide-liquide représentée par un tube autour duquel se trouve le matériau à changement de phase. Le système est soumis à une charge oscillant entre le chauffage et le refroidissement. Une analyse d’ordre de grandeur permet de prédire le comportement du système en fonction des principaux nombres adimensionnels. Un paramètre adimensionnel est proposé pour délimiter les concepts dans lesquels la conduction domine par rapport à ceux où la convection naturelle domine. L’étude dévoile l’impact des paramètres de conception de l’unité de stockage thermique sur son fonctionnement et approfondit les connaissances dans le domaine du changement de phase avec convection naturelle. Différents indicateurs ont été développés pour analyser la performance du système, tels que les dimensions de la zone affectée thermiquement, le volume fondu ou solidifié et une analyse fréquentielle. Des corrélations sont proposées pour déterminer facilement le comportement du système.

Serous cystadenofibroma of the Fallopian tube. Case report and literature review

Introduction. Cystadenofibromas of the Fallopian tube are very rare benign tumors of the female genital tract. These tumours are usually asymptomatic and are found incidentally. Case report. We describe a Fallopian serous cystadenofibroma in a 50 year-old woman operated for uterine leiomyoma. The histopathologic finding revealed a cystic lesion connected to the salpinx. The cyst was composed of connective stroma lined by epithelial cuboidal cells, without pleomorfism or detectable mitoses. Pseudopapillary structures were observed in the lumen of the cyst. The patient is well on follow-up. Conclusion. The origin of serous cystadenofibroma of the Fallopian tube is not clear. The tumor is considered an embryologic remnant rather than a proliferating neoplastic process. These tumours seem to have a benign course and a malignant potential has not been described.

Does the nasogastric tube has a role in elective colo-rectal surgery?

Introduction. Routine use of nasogastric tubes (NGT) after abdominal operations is intended to hasten the return of bowel function, diminish the risk of anastomotic leakage and prevent pulmonary complications. The aim of our study was to prospectively assess the tolerability and the safety of the non use of NGT after elective colorectal open operations. Patients and methods. Between March 2009 and December 2010, 110 consecutive patients underwent colo-rectal elective open surgery for neoplasm without nasogastric decompression. We analyzed the incidence of nausea and vomiting, the pulmonary complications, the return of bowel function the deep wound breakdown (fascial dehiscence) and the anastomotic leakage. Results. Only 15 patients (13,6%) reported nausea without vomiting immediately after surgery and 9 cases of vomiting were observed (8%), requiring the insertion of the NGT (nasogastric tube) in 5 (4,5%). A total of 105 patients (96,3%) were NGT free. No deep wound dehiscence was observed and only one real pneumonia occurred. Anastomotic dehiscence occured in 4 patients (3,6%) and a second surgical procedure was needed in three cases. The return of bowel function, except in the last four patients, occurred in 3,8 days average (range 2-7 days). Conclusion. We confirm the uselessness of the NGT in the framework of fast track program adopted in elective open colo-rectal surgery.

Defensin-Like ZmES4 Mediates Pollen Tube Burst in Maize via Opening of the Potassium Channel KZM1

In contrast to animals and lower plant species, sperm cells of flowering plants are non-motile and are transported to the female gametes via the pollen tube, i.e. the male gametophyte. Upon arrival at the female gametophyte two sperm cells are discharged into the receptive synergid cell to execute double fertilization. The first players involved in inter-gametophyte signaling to attract pollen tubes and to arrest their growth have been recently identified. In contrast the physiological mechanisms leading to pollen tube burst and thus sperm discharge remained elusive. Here, we describe the role of polymorphic defensin-like cysteine-rich proteins ZmES1-4 (Zea mays embryo sac) from maize, leading to pollen tube growth arrest, burst, and explosive sperm release. ZmES1-4 genes are exclusively expressed in the cells of the female gametophyte. ZmES4-GFP fusion proteins accumulate in vesicles at the secretory zone of mature synergid cells and are released during the fertilization process. Using RNAi knock-down and synthetic ZmES4 proteins, we found that ZmES4 induces pollen tube burst in a species-preferential manner. Pollen tube plasma membrane depolarization, which occurs immediately after ZmES4 application, as well as channel blocker experiments point to a role of K(+)-influx in the pollen tube rupture mechanism. Finally, we discovered the intrinsic rectifying K(+) channel KZM1 as a direct target of ZmES4. Following ZmES4 application, KZM1 opens at physiological membrane potentials and closes after wash-out. In conclusion, we suggest that vesicles containing ZmES4 are released from the synergid cells upon male-female gametophyte signaling. Subsequent interaction between ZmES4 and KZM1 results in channel opening and K(+) influx. We further suggest that K(+) influx leads to water uptake and culminates in osmotic tube burst. The species-preferential activity of polymorphic ZmES4 indicates that the mechanism described represents a pre-zygotic hybridization barrier and may be a component of reproductive isolation in plants.