Linear recursive odometers and beta-expansions

The aim of this paper is to study the connection between different properties related to $\beta$-expansions. In particular, the relation between two conditions, both ensuring pure discrete spectrum of the odometer, is analysed. The first one is the so-called Hypothesis B for the $G$-odometers and the second one is denoted by (QM) and it has been introduced in the framework of tilings associated to Pisot $\beta$-numerations

An adaptive sampling method for global sensitivity analysis based on least-squares support vector regression

In the field of engineering, surrogate models are commonly used for approximating the behavior of a physical phenomenon in order to reduce the computational costs. Generally, a surrogate model is created based on a set of training data, where a typical method for the statistical design is the Latin hypercube sampling (LHS). Even though a space filling distribution of the training data is reached, the sampling process takes no information on the underlying behavior of the physical phenomenon into account and new data cannot be sampled in the same distribution if the approximation quality is not sufficient. Therefore, in this study we present a novel adaptive sampling method based on a specific surrogate model, the least-squares support vector regresson. The adaptive sampling method generates training data based on the uncertainty in local prognosis capabilities of the surrogate model - areas of higher uncertainty require more sample data. The approach offers a cost efficient calculation due to the properties of the least-squares support vector regression. The opportunities of the adaptive sampling method are proven in comparison with the LHS on different analytical examples. Furthermore, the adaptive sampling method is applied to the calculation of global sensitivity values according to Sobol, where it shows faster convergence than the LHS method. With the applications in this paper it is shown that the presented adaptive sampling method improves the estimation of global sensitivity values, hence reducing the overall computational costs visibly

Nonlinear model predictive control methodology for efficiency and durability improvement in a fuel cell power system

The main contribution of this work is the improvement of the efficiency of a PEMFC power system while guaranteeing conditions that also improve its durability. Adopting the NMPC scheme with the distributed parameter model and the nonlinear observer, the efficiency of the PEMFC-based system can be maximized guaranteeing at the same time the appropriate internal gas concentration profiles to avoid global and local hydrogen and oxygen starvation and proper membrane humidification.Peer ReviewedPostprint (author's final draft

A Politics of Dwelling: Local Knowledge and Linked Communities on the Lake Superior North Shore

This dissertation explores how stakeholders of working-class communities and First Nations in Northwestern Ontario along the Lake Superior north shore express a politics of dwelling and their own sense of place in regard to their social and natural environments. The work stresses the importance of local knowledge as a means of community building and knowledge production, and strives to map how the land and landscapes are valued by those who live and work in this region. My methodological approach combines visual methods with autoethnography, since as the researcher, I have a formative and long-term family history in the locations of my study, as well as an ongoing practice of producing personal creative projects and artworks in and about the north shore region. The dissertation’s material structure is presented as a dual construction: this written thesis and a 44 minute documentary film, Conversations on the Lake. My prior history as an independent filmmaker and lens-based visual artist has shaped my scholarly practice, so that my research findings are best expressed using a combination of textual and audio/visual methods. My primary research tool in undertaking the qualitative research interviews that support this dissertation is the camera. Following transcription and analysis, the filmed interview material was organized into the following themes: the role of class in rural northern resource-based communities, the dualisms and tensions between conservation and extraction of natural resources, the intersections of local, regional, and global politics affecting environmental themes in the area of my study, and the local landscape as a unique and relevant character in the culture of Northwestern Ontario. What my research and filmed interviews in the communities of the Lake Superior north shore region have unveiled are an evolving sense of place and belonging, as experienced by actors living and working there. Since beginning this work, new ecological and social themes have continually emerged as stories for investigation and exploration. The shifting progression of my narrative enquiry is a web of interconnected stories along a mobile, transformative geography

Deliberation across Deep Divisions. Transformative Moments

In group discussions of any kind there tends to be an up and down in the level of deliberation. To capture this dynamic we coined the concept of Deliberative Transformative Moments (DTM). In deeply divided societies deliberation is particularly important in order to arrive at peace and stability, but deliberation is also very difficult to be attained. Therefore, we wanted to learn about the conditions that in group discussions across the deep divisions of such societies help deliberation. We organized such group discussions between ex-guerrillas and ex-paramilitaries in Colombia, Serbs and Bosnjaks in Srebrenica, and poor residents and local police officers in the favelas (slums) of Brazil. We could identify factors that help to transform discussions from low to high deliberation and risk transformations in the opposite direction. We could also identify factors that help to keep a discussion at a high level of deliberation, and, in a next step, we could determine to what extent long sequences of deliberation had a positive impact on the outcomes of the discussions. Finally, we show how our research results can have a long term effect if it is used in schools of such deeply divided societies

Deliberation across Deep Divisions. Transformative Moments

From the local level to international politics, deliberation helps to increase mutual understanding and trust, in order to arrive at political decisions of high epistemic value and legitimacy. This book gives deliberation a dynamic dimension, analysing how levels of deliberation rise and fall in group discussions, and introducing the concept of 'deliberative transformative moments' and how they can be applied to deeply divided societies, where deliberation is most needed but also most difficult to work. Discussions between ex-guerrillas and ex-paramilitaries in Colombia, Serbs and Bosnjaks in Bosnia-Herzegovina, and police officers and locals in Brazilian favelas are used as case studies, with participants addressing how peace can be attained in their countries. Allowing access to the records and transcripts of the discussions opens an opportunity for practitioners of conflict resolution to apply this research to their work in trouble spots of the world, creating a link between the theory and practice of deliberation

Nonlinear predictive control for durability enhancement and efficiency improvement in a fuel cell power system

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this work, a nonlinear model predictive control (NMPC) strategy is proposed to improve the efficiency and enhance the durability of a proton exchange membrane fuel cell (PEMFC) power system. The PEMFC controller is based on a distributed parameters model that describes the nonlinear dynamics of the system, considering spatial variations along the gas channels. Parasitic power from different system auxiliaries is considered, including the main parasitic losses which are those of the compressor. A nonlinear observer is implemented, based on the discretised model of the PEMFC, to estimate the internal states. This information is included in the cost function of the controller to enhance the durability of the system by means of avoiding local starvation and inappropriate water vapour concentrations. Simulation results are presented to show the performance of the proposed controller over a given case study in an automotive application (New European Driving Cycle). With the aim of representing the most relevant phenomena that affects the PEMFC voltage, the simulation model includes a two-phase water model and the effects of liquid water on the catalyst active area. The control model is a simplified version that does not consider two-phase water dynamics.Peer ReviewedPostprint (author's final draft

Burnout status of healthcare workers in the world during the peak period of the COVID-19 pandemic

During the COVID-19 pandemic, healthcare workers have a high workload and have been exposed to various psychosocial stressors. This study aimed to evaluate health workers during the COVID-19 pandemic in the world. The method used in this research is qualitative with a literature review approach. The data sources in this study were taken from the Scopus database using the keywords “health workers,” “burnout,” AND “coronavirus” from the time range of 2020 to April 25, 2022. From the determination of the time range, 150 documents emerged. This study revealed that the Pearson correlation between total burnout scale scores on healthcare workers, professionals, exhaustion, mental, stress, personal, depression, symptoms, emergency, system, job, and impact indicated that overall burnout scores were associated with depression and anxiety. Stress symptoms had correlation values ranging from 0.84 to 0.73. Job burnout had a significant relationship with exhaustion at 0.89; depression r = 0.73), impacting a score of 0.66. At the same time, the fulfillment of professional and interpersonal disengagement showed a Pearson correlation between the total burnout scale scores on health workers, professionals, exhaustion, mental, stress, personal, depression, symptoms, emergency, system, job, and impact. Overall, the participants in health care workers worldwide experienced high levels of psychological distress. We also found that health workers dealing with COVID-19 pandemic patients were more likely to experience depression, stress, and burnout than health staff who were not personally involved in medical work. Furthermore, this study will be a follow-up study using the Work Ability Index (WAI) to measure work ability and work satisfaction