Creep monitoring using permanently installed potential drop sensors

Creep is the primary life limiting mechanism of static high temperature, high pressure power station components. Creep state evaluation is currently achieved by surface inspection of microstructure during infrequent outages; a methodology which is laborious, time consuming and considered inadequate. The objective of this work is to develop a monitoring technique that is capable of on-load creep damage monitoring. A continuous update of component integrity will enable better informed, targeted inspections and outage maintenance providing increased power generation availability. A low-frequency, permanently installed potential drop system has been previously developed and will be the focus of this thesis. The use of a quasi-DC inspection frequency suppresses the influence of the electromagnetic skin effect that would otherwise undermine the stability of the measurement in the ferromagnetic materials of interest; the use of even low frequency measurements allows phase sensitive detection and greatly enhanced noise performance. By permanently installing the electrodes to the surface of the component the resistance measurement is sensitive to strain. A resistance - strain inversion is derived and validated experimentally; the use of the potential drop sensor as a robust, high temperature strain gauge is therefore demonstrated. The strain rate of a component is known to be an expression of the creep state of the component. This concept was adopted to develop an interpretive framework for inferring the creep state of a component. It is possible to monitor the accumulation of creep damage through the symptomatic relative increase in strain rate. By taking the ratio of two orthogonal strain measurements, instability and drift common to both measurements can be effectively eliminated; an important attribute considering the necessity to monitor very low strain rates over decades in time in a harsh environment. A preliminary study of using the potential drop technique for monitoring creep damage at a weld has been conducted. Welds provide a site for preferential creep damage accumulation and therefore will frequently be the life limiting feature of power station components. The potential drop technique will be sensitive to both the localised strain that is understood to act as precursor to creep damage at a weld and also the initiation and growth of a crack. Through the course of this project, two site trials have been conducted in power stations. A measurement system and high temperature hardware that is suitable for the power station environment has been developed. The focus of this thesis is the effective transfer of the technique to industry; the realisation of this is detailed in the final chapter.Open Acces

Smart Augmentation - Learning an Optimal Data Augmentation Strategy

A recurring problem faced when training neural networks is that there is typically not enough data to maximize the generalization capability of deep neural networks(DNN). There are many techniques to address this, including data augmentation, dropout, and transfer learning. In this paper, we introduce an additional method which we call Smart Augmentation and we show how to use it to increase the accuracy and reduce overfitting on a target network. Smart Augmentation works by creating a network that learns how to generate augmented data during the training process of a target network in a way that reduces that networks loss. This allows us to learn augmentations that minimize the error of that network. Smart Augmentation has shown the potential to increase accuracy by demonstrably significant measures on all datasets tested. In addition, it has shown potential to achieve similar or improved performance levels with significantly smaller network sizes in a number of tested cases

Education and better citizenship:

Thesis (M.A.)--Boston University, 1931. This item was digitized by the Internet Archive

Survey of the business education phase of the public high school libraries of Massachusetts.

Thesis (Ed.M.)--Boston Universit

The Lived Experience of Bipolar Disorder: A Systematic Review and Meta-Synthesis

The purpose of this meta-synthesis was to review the available qualitative research on the lived experience of persons with bipolar disorder in order to find common themes that may enhance practitioner understanding. In this meta-synthesis, limited to studies conducted in the United States, 12 studies involving 234 participants met the authors’ inclusion criteria, and the following four major crosscutting themes, with subthemes, were identified: the process of acceptance of the diagnosis; its negative impact on relationships; internal coping strategies; and reliance on social support. Implications of these findings for direct practice are explored

Solving a Coupling Unbalance Problem in the Field

Case StudyWhen a large (3.4 meters long) diaphragm coupling was suspected of causing excessive (120 microns p-p) 1X unbalance vibration between a 90+ Megawatt Gas Turbine and a Propane Compressor in an LNG plant, there was not time to ship the coupling back to a distant factory or service center for troubleshooting. Simple field diagnostic techniques were used to discover the problem, which then led to a field correction and repair so that the unit was able to be quickly restarted with minimum downtime

CoopeTárcoles, Costa Rica. Equator Initiative Case Study Series

The artisanal fishers of the community of Tárcoles, located in the Gulf of Nicoya on the Pacific coast of North America (Central America)-Costa Rica; faced declining fish stocks due to a combination of overharvesting by commercial shrimp boats and unsustainable local fishing practices. At the same time, development of the tourism sector along the coast threatened to restrict access to the shore and to marginalize their work. The local fishing cooperative Coope Tárcoles R.L. was founded in 1985 to confront these twin threats. At the forefront of these efforts has been the development of fishing bylaws that stress sustainable practices, enshrined in the community's 'Code of Responsible Fishing'. In partnership with CoopeSolidar R.L., the initiative launched a sustainable and community-based ecotourism venture in 2007 to provide an alternative source of income for local residents. In 2009, meanwhile, the group was successful in gaining approval of a community-managed marine area

A Comparative Study of Image-to-Image Translation Using GANs for Synthetic Child Race Data

The lack of ethnic diversity in data has been a limiting factor of face recognition techniques in the literature. This is particularly the case for children where data samples are scarce and presents a challenge when seeking to adapt machine vision algorithms that are trained on adult data to work on children. This work proposes the utilization of image-to-image transformation to synthesize data of different races and thus adjust the ethnicity of children's face data. We consider ethnicity as a style and compare three different Image-to-Image neural network based methods, specifically pix2pix, CycleGAN, and CUT networks to implement Caucasian child data and Asian child data conversion. Experimental validation results on synthetic data demonstrate the feasibility of using image-to-image transformation methods to generate various synthetic child data samples with broader ethnic diversity.Comment: The Paper is accepted in 25th Irish Machine Vision and Image Processing Conference (IMVIP23