40 research outputs found

    A New Course in Defense Manufacturing – An Introduction to Shipbuilding

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    This paper discusses the development and deployment of a new course in DMEI (Defense Manufacturing Engineering Innovation) titled, “Introduction to Shipbuilding.” This course has been taught using Zoom since 2021 at both the University of Texas Rio Grande Valley, a Hispanic Serving Institution, and Virginia State University, a Historically Black University. After a brief literature review, an outline of the course is presented with topics including the maritime market for shipbuilding, economics of shipbuilding, the classification agencies, metallurgy and welding processes, ship structure and assembly, shipyard layout, accuracy control, and shipbuilding planning and scheduling. Difficulties in obtaining an appropriate textbook and the use of guest lecturers are discussed. Student survey data is presented, and conclusions are drawn about this course

    Benefits of Implementing Automated Costing in a Small Machine Shop: A Case Study

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    Knowledge based cost estimating systems are available, but is there a lower limit to their applicability in an industrial environment?  This paper answers this question by examining a knowledge based cost estimating expert system application in a small machine shop.  Differences between the traditional experienced-based system currently employed and the automated system are studied.  Data is gathered to analyze time effectiveness, accuracy, and payback of the software.  Data from seventy part models is recorded to study the time experiment and data from fifty part models is used to study accuracy and consistency.The results indicate that the software is faster than traditional quoting systems; however, the payback point is high. Also, results show that the software has a smaller average time to manufacture percent difference between the automated system and the actual time to manufacture (TTM) compared to the percentage difference between the traditional TTM and actual TTM. Standard deviation for the automation is also less, implying better consistency.  As a result, the attractiveness of the automated system in the limiting case of a small machine shop rests with significantly improved accuracy and consistency rather than payback.

    Coordinated analysis of age, sex, and education effects on change in MMSE scores

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    Objectives. We describe and compare the expected performance trajectories of older adults on the Mini-Mental Status Examination (MMSE) across six independent studies from four countries in the context of a collaborative network of longitudinal studies of aging. A coordinated analysis approach is used to compare patterns of change conditional on sample composition differences related to age, sex, and education. Such coordination accelerates evaluation of particular hypotheses. In particular, we focus on the effect of educational attainment on cognitive decline.Method. Regular and Tobit mixed models were fit to MMSE scores from each study separately. The effects of age, sex, and education were examined based on more than one centering point.Results. Findings were relatively consistent across studies. On average, MMSE scores were lower for older individuals and declined over time. Education predicted MMSE score, but, with two exceptions, was not associated with decline in MMSE over time.Conclusion. A straightforward association between educational attainment and rate of cognitive decline was not supported. Thoughtful consideration is needed when synthesizing evidence across studies, as methodologies adopted and sample characteristics, such as educational attainment, invariably differ. © 2012 The Author

    Timescapes of Himalayan hydropower: promises, project life cycles, and precarities

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    In this paper, we review the existing social science scholarship focused on hydropower development in the Himalayan region, using an interpretive lens attuned to issues of time and temporality. While the spatial politics of Himalayan hydropower are well examined in the literature, an explicit examination of temporal politics is lacking. In this paper, we present a conceptual framework organized around the heuristic of timescapes, highlighting temporal themes implicit in the existing literature. In three sections, we explore the temporal politics of anticipation that shape hydropower dreams, the intersecting temporalities and rhythms that modulate the life cycles of hydropower projects, and the ways that geological and hydrological time affect both hydropower development and broader Himalayan futures. Along the way, we pose a series of questions useful for framing future research given the significant climatic, geophysical, and sociopolitical changes underway in the Himalayan bioregion, calling for greater analytical attention to time, temporality, and temporal ethics in future studies of hydropower in the Himalayas and beyond.Austin Lord, Georgina Drew, Mabel Denzin Gerga

    Thermal Evolution and Magnetic Field Generation in Terrestrial Planets and Satellites

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    Assessment of the physical characteristics and stormwater effluent quality of permeable pavement systems containing recycled materials

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    This paper evaluates the physical characteristics of two recycled materials and the pollutant removal efficiencies of four 0.2 m2 tanked permeable pavement rigs in the laboratory, that contained either natural aggregates or these recycled materials in the sub-base. The selected recycled materials were Crushed Concrete Aggregates (CCA) and Cement-bounded Expanded Polystyrene beads (C-EPS) whilst the natural aggregates were basalt and quartzite. Natural stormwater runoff was used as influent. Effluent was collected for analysis after 7–10 mins of discharge. Influent and effluent were analysed for pH, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), Electroconductivity (EC), turbidity, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Nitrate-Nitrogen (NO3-N), reactive phosphorous (PO43-) and sulphates (SO42-). Both CCA and C-EPS had suitable physical properties for use as sub-base materials in PPS. However, C-EPS is recommended for use in pavements with light to no traffic because of its relatively low compressive strength. In terms of pollutant removal efficiencies, significant differences (p 0.05) were found with respect to TSS, turbidity, COD and NO3-N. Effluent from rigs containing CCA and C-EPS saw significant increases in pH, EC and TDS measurements whilst improvements in DO, TSS, turbidity, COD, PO43- and SO42- were observed. All mean values except pH were, however, within the Maximum Permissible Levels (MPLs) of water pollutants discharged into the environment according to the Trinidad and Tobago Environmental Management Authority (EMA) or the United States Environmental Protection Agency (US EPA). In this regard, the CCA and C-EPS performed satisfactorily as sub-base materials in the permeable pavement rigs. It is noted, however, that further analysis is recommended through leaching tests on the recycled materials
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