Investigation of the Relationship Between Particulate Bound Mercury and Properties of Fly Ash in a Full-Scale 100 MWE Pulverized Coal Combustion Boiler

There is an increasing concern over mercury emissions from coal-fired boilers. Coal-fired power generation accounts for approximately 33% of total mercury emission in the United States. Once it is emitted into the atmosphere and deposited on land or water, mercury can transform into methylmercury, an organic form. Mercury can then enter the food chain, which poses a potential threat to human health and the environment. To study the relationship between particulate bound mercury and fly ash properties, fly ash samples were collected from the mechanical hopper (MHP) and the electrostatic precipitator (ESP) of a 100 MWe pulverized coal-fired boiler and analyzed for particulate mercury concentration (Hgp), unburned carbon, loss on ignition (LOI), elemental content and specific surface area (SSA). Different types of software, such as Microsoft Excel, Minitab and Origin, were applied to build the regression models to evaluate the relationship between Hgp and fly ash properties. The results of the analysis indicate that the amount of mercury emissions is dependent on the properties of the fly ash at the MHP and ESP as well as the amount of fly ash removed by air pollution control devices (APCD). Their relationship can be described as: Hgp (MHP), ppm = 0.0230 + 0.00838 Carbon (MHP), % + 0.00385 LOI (MHP), % Hgp (ESP), ppm = -0.0180 + 0.0670 Carbon (ESP), % + 0.0448 LOI (ESP), % The SSA of ESP ash is larger than MHP ash, which can help explain why Hgp at the ESP is higher than at the MHP. For the multiple metal oxides in fly ash, all the regression results indicate the trace elements have a very weak relationship with Hgp. There is no significant effect from trace elements on mercury absorption. Further study of Hgp catalyst mechanism and absorption phenomenon is ongoing. The function of various emission control technologies such as SCR and hot-side ESP in some coal-fired power plants are being evaluated

Online Pricing with Offline Data: Phase Transition and Inverse Square Law

This paper investigates the impact of pre-existing offline data on online learning, in the context of dynamic pricing. We study a single-product dynamic pricing problem over a selling horizon of $T$ periods. The demand in each period is determined by the price of the product according to a linear demand model with unknown parameters. We assume that before the start of the selling horizon, the seller already has some pre-existing offline data. The offline data set contains $n$ samples, each of which is an input-output pair consisting of a historical price and an associated demand observation. The seller wants to utilize both the pre-existing offline data and the sequential online data to minimize the regret of the online learning process. We characterize the joint effect of the size, location and dispersion of the offline data on the optimal regret of the online learning process. Specifically, the size, location and dispersion of the offline data are measured by the number of historical samples $n$, the distance between the average historical price and the optimal price $\delta$, and the standard deviation of the historical prices $\sigma$, respectively. We show that the optimal regret is $\widetilde \Theta\left(\sqrt{T}\wedge \frac{T}{(n\wedge T)\delta^2+n\sigma^2}\right)$, and design a learning algorithm based on the "optimism in the face of uncertainty" principle, whose regret is optimal up to a logarithmic factor. Our results reveal surprising transformations of the optimal regret rate with respect to the size of the offline data, which we refer to as phase transitions. In addition, our results demonstrate that the location and dispersion of the offline data also have an intrinsic effect on the optimal regret, and we quantify this effect via the inverse-square law.Comment: Forthcoming in Management Scienc

A Study on the Open Source Digital Library Software's: Special Reference to DSpace, EPrints and Greenstone

The richness in knowledge has changed access methods for all stake holders in retrieving key knowledge and relevant information. This paper presents a study of three open source digital library management software used to assimilate and disseminate information to world audience. The methodology followed involves online survey and study of related software documentation and associated technical manuals.Comment: 9 Pages, 3 Figures, 1 Table, "Published with International Journal of Computer Applications (IJCA)

The Power of Stories: The Experiences and Well-Being of Mental Health Providers Working in Northern Saskatchewan Communities

THE POWER OF STORIES: THE EXPERIENCES AND WELL-BEING OF MENTAL HEALTH PROVIDERS WORKING IN NORTHERN SASKATCHEWAN COMMUNITIES Wanda Seidlikoski Yurach, PhD Candidate, Health Sciences, College of Medicine, University of Saskatchewan This study explores the experiences of outsider mental health providers (MHPs) and the impact of delivering trauma-informed care/counselling in northern Saskatchewan First Nations communities (NSFNCs). With limited information and increased demand for mental health supports in NSFNCs it is important to tap into MHPs’ experiences and insights. An Approval Certificate (Beh ID 851) was received from the University of Saskatchewan’s Behavioural Research Ethics Board prior to commencing this project. An embedded mixed methods research design was utilized guided by participatory narrative inquiry to support participants to be involved in all aspect of this project. A sample of ten female MHPs (Health Canada approved social workers) that have travelled into NSFNCs to work were interviewed in three phases. Narrative interviews indicated working in NSFNCs was both inspiring and tragic revealing these major themes: work complexity; lack of safety; awakening/transformation; power of relationships; reconciliation; impact on well-being; lessons learned; and needed supports. Although MHPs’ love their work, clients and communities, many have discontinued northern trauma work due to the isolation, job demands, and lack of safety and well-being supports. Well-being was examined qualitatively through participants’ stories and described as balance or overall wellness within life and work. Well-being was also quantitatively assessed using the Professional Quality of Life Scale-5 (Pro-QOL-5), a self-administered questionnaire measuring compassion satisfaction and compassion fatigue (burnout/secondary trauma). ProQOL-5 results found 60% of participants had high levels of compassion satisfaction; 70% experienced low levels of burn out; and, 70% experienced moderate levels of secondary trauma. MHPs collectively made the following recommendations to protect their well-being and improve the quality of their work environments: adopt a team approach; address safety concerns; improve management/MHP relationships; develop a trauma-informed training curriculum, specific to NSFNC work; improve MHP approval and hiring guidelines; and, expand access to professional supports including a ‘community of practice’. By understanding NSFNC trauma work and its impact, MHPs are better able, to make evidence-informed recommendations to support their well-being, reduce isolation, and improve the quality of their work environments. This in turn, could help attract and retain experienced MHPs, thereby improving the quality of services to facilitate healing for and with NSFNCs

Attenuation of the Sensing Capabilities of PhoQ in Transition to Obligate Insect–Bacterial Association

Sodalis glossinidius, a maternally inherited endosymbiont of the tsetse fly, maintains genes encoding homologues of the PhoP-PhoQ two-component regulatory system. This two-component system has been extensively studied in facultative bacterial pathogens and is known to serve as an environmental magnesium sensor and a regulator of key virulence determinants. In the current study, we show that the inactivation of the response regulator, phoP, renders S. glossinidius sensitive to insect derived cationic antimicrobial peptides (AMPs). The resulting mutant strain displays reduced expression of genes involved in the structural modification of lipid A that facilitates resistance to AMPs. In addition, the inactivation of phoP alters the expression of type-III secretion system (TTSS) genes encoded within three distinct chromosomal regions, indicating that PhoP-PhoQ also serves as a master regulator of TTSS gene expression. In the absence of phoP, S. glossinidius is unable to superinfect either its natural tsetse fly host or a closely related hippoboscid louse fly. Furthermore, we show that the S. glossinidius PhoQ sensor kinase has undergone functional adaptations that result in a substantially diminished ability to sense ancestral signals. The loss of PhoQ's sensory capability is predicted to represent a novel adaptation to the static symbiotic lifestyle, allowing S. glossinidius to constitutively express genes that facilitate resistance to host derived AMPs

Revision based total semantics for extended normal logic programs

Dissertação para obtenção do Grau de Doutor em Matemática - Lógica e Fundamentos da MatemáticaFundação para a Ciência e Tecnologia - SFRH/ PROTEC/49747/200

Role of convection in redistributing formaldehyde to the upper troposphere over North America and the North Atlantic during the summer 2004 INTEX campaign

Measurements of formaldehyde (CH2O) from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC‐8 aircraft during the summer 2004 INTEX‐NA campaign to test our understanding of convection and CH2O production mechanisms in the upper troposphere (UT, 6–12 km) over continental North America and the North Atlantic Ocean. The present study utilizes these TDLAS measurements and results from a box model to (1) establish sets of conditions by which to distinguish “background” UT CH2O levels from those perturbed by convection and other causes; (2) quantify the CH2O precursor budgets for both air mass types; (3) quantify the fraction of time that the UT CH2O measurements over North America and North Atlantic are perturbed during the summer of 2004; (4) provide estimates for the fraction of time that such perturbed CH2O levels are caused by direct convection of boundary layer CH2O and/or convection of CH2O precursors; (5) assess the ability of box models to reproduce the CH2O measurements; and (6) examine CH2O and HO2 relationships in the presence of enhanced NO. Multiple tracers were used to arrive at a set of UT CH2O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. In general, production of CH2O from CH4 was found to be the dominant source term, even in perturbed air masses. This was followed by production from methyl hydroperoxide, methanol, PAN‐type compounds, and ketones, in descending order of their contribution. At least 70% to 73% of the elevated UT observations were caused by enhanced production from CH2O precursors rather than direct transport of CH2O from the boundary layer. In the presence of elevated NO, there was a definite trend in the CH2O measurement–model discrepancy, and this was highly correlated with HO2 measurement–model discrepancies in the UT