471 research outputs found

    Analysis of Thermal Interconnectivity of Utilities in Rural Alaska

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    Presented to the Faculty of the University of Alaska Anchorage in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCEThroughout the arctic there are two primary community utilities with dramatically contrary thermodynamic concerns. These are the intensely exothermic diesel electric power generation, and the strongly endothermic water and sewer utility. In this context exothermic processes must expel excess heat while endothermic process requires heat input. Failure of engineers, community planners, funding agencies, and interest groups to recognize the full social, economic, and environmental impact to the sustainability of utilities has come at tremendous cost. This is exemplified in many remote Alaskan communities such as Toksook Bay, Minto, Deering, and Kotlik

    Two Species Evolutionary Game Model of User and Moderator Dynamics

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    We construct a two species evolutionary game model of an online society consisting of ordinary users and behavior enforcers (moderators). Among themselves, moderators play a coordination game choosing between being "positive" or "negative" (or harsh) while ordinary users play prisoner's dilemma. When interacting, moderators motivate good behavior (cooperation) among the users through punitive actions while the moderators themselves are encouraged or discouraged in their strategic choice by these interactions. We show the following results: (i) We show that the ω\omega-limit set of the proposed system is sensitive both to the degree of punishment and the proportion of moderators in closed form. (ii) We demonstrate that the basin of attraction for the Pareto optimal strategy (Cooperate,Positive)(\text{Cooperate},\text{Positive}) can be computed exactly. (iii) We demonstrate that for certain initial conditions the system is self-regulating. These results partially explain the stability of many online users communities such as Reddit. We illustrate our results with examples from this online system.Comment: 8 pages, 4 figures, submitted to 2012 ASE Conference on Social Informatic

    A Tribute to One of Arkansas\u27s Greatest Pioneers of Progress

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    STUDENT PERCEPTION OF PREPAREDNESS IN THE MIDST OF COVID-19: A SNAPSHOT FROM FIRST YEAR CHEMISTRY STUDENTS

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    The transition from high school to tertiary education can present many challenges for students. First year students must navigate new formal curricular, societal norms, physical environments, and support networks. An important factor for a successful transition from secondary to tertiary education is student preparedness. This transition period was thrown on its head due to the global challenges that the COVID-19 pandemic presented in 2020. The aim of this research was to identify and examine the perceptions of preparedness of first-year chemistry students, and if these perceptions were significantly impacted by COVID-19. Surveys were deployed to a first-year chemistry cohort at both the start and the end of semester, and follow up focus groups conducted after the conclusion of the semester. Results indicate that students’ perceptions of preparedness for studying chemistry increased over the course of the semester, however for studying at university in general the perception of preparedness decreased. The absence of in-person laboratory practicals was found to be a great concern for students, along with factors previously found to impact students’ perceptions. Reflections and findings of the students’ experiences will be presented from the first semester of 2020 delivered online through emergency remote teaching and learning

    Delivery of a baby with severe combined immunodeficiency at 31 weeks gestation following an extreme preterm prelabour spontaneous rupture of the membranes: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>If left untreated, severe combined immunodeficiency can lead to an acute susceptibility to infection. The intrauterine environment is sterile until the amniotic membranes rupture. The vaginal flora then ascends into the genital tract, thus increasing the risk of chorioamnionitis. An extremely premature and prolonged membrane rupture is associated with a dismal prognosis for an immunocompetent preterm fetus. There are no case reports to date that detail the outcome of an immunocompromised preterm baby following prolonged rupture of membranes.</p> <p>Case presentation</p> <p>We present the case of a 32-year-old Indian woman who delivered a 31-week gestational baby who had a severe combined immunodeficiency following premature prelabour prolonged rupture of the membranes at the 14<sup>th </sup>week of gestation.</p> <p>Conclusion</p> <p>Extreme preterm prelabour spontaneous rupture of membranes in an underlying condition of severe combined immunodeficiency does not necessarily lead to an unfavourable outcome.</p

    The analysis, simulation and control of cycloconverter drives for ship propulsion

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    Naval expeditionary forces of the future will require new, technologically advanced, multi-mission surface combatants. The design philosophy for future surface combatants stresses survivability, efficiency, and modularity through the use of a modern open architecture consisting of commercial off the shelf and dual use systems. An integrated propulsion and electrical power generation system which utilizes advanced, commercially viable power electronics and state of the art control and monitoring systems is viewed as the appropriate system for the future surface combatant. This study provides the designing naval engineer with technical background information and design considerations for the application of a cycloconverter drive for ship propulsion in an integrated power system. The cycloconverter is a power electronic circuit which performs a single stage conversion of an ac input voltage at one frequency to an ac output voltage of variable frequency and amplitude. Cycloconverters are generally used for low speed, very large horsepower applications and with suitable closed loop control can develop torque and speed responses suitable for ship propulsion. External performance characteristics and control issues for the cycloconverter are discussed, followed by a time domain computer simulation of an integrated ship propulsion drive utilizing a cycloconverter. From the technical background information, external performance characteristics and computer simulation analysis, the designing naval engineer can make educated decisions on the application of a cycloconverter drive for ship propulsion.http://archive.org/details/thenalysissimula1094532014NAU.S. Navy (U.S.N.) authorApproved for public release; distribution is unlimited

    The search for an ionospheric model suitable for real-time applications in HF radio communications

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    Statement of work: In essence the research work was to focus on the development of an ionospheric model suitable for real time HF frequency prediction and direction finding applications. The modelling of the ionosphere had to be generic in nature, sufficient to ensure that the CSIR could simultaneously secure commercial competitiveness in each of the three niche market areas aforementioned, while requiring only minimal changes to software architecture in the case of each application. A little research quickly showed that the development of an ionospheric model capable of driving a HFDFSSL system in "real time" would result in one having to make only slight re-structuring of the software to facilitate application of the same model in the areas of real time frequency prediction and spectrum management. The decision made at the outset of the project to slant the research toward the development of a model best suited for HF direction finding applications is reflected in the avenues followed during the course of the modelling proces

    Allocation of Functions in a Far-Term Air Traffic Control Environment

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    A human-in-the-loop exploration of a ground-based automated separation assurance concept was conducted that involved the allocation of certain functions between humans and automation. This exploration included operations that were sustained for prolonged periods of time with high levels of traffic in the presence of convective weather and scheduling constraints. An investigation into the acceptability of the defined roles and performance of tasks was conducted where it was found that the participants rated the concept and allocation of functions with a high level of acceptability. However, issues were encountered with the automation related to the detection of and response to tactical conflicts. Lower ratings were given on account of these concerns, and it was found that a key contributor to the underlying problems was transitioning aircraft and the uncertainty of their trajectories. Stemming from those results, participants responded that they would rather have direct control over aircraft transitions as well as more control over the tactical conflict resolution automation. In contrast, participants responded that they would rather have the automation place aircraft back on trajectory, and perform weather avoidance and scheduling tasks
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