579 research outputs found

    Remote sensing of optically shallow, vertically inhomogeneous waters: A mathematical model

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    A multiple-layer radiative transfer model of a vertically inhomogeneous, optically shallow water mass is briefly described. This model is directed toward use in remote sensing properties. Some preliminary results and qualitative predictions are presented

    An Inverted Teaching Model for a Mechanics of Materials Course

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    Instructors at Missouri University of Science and Technology have been offering certain sections of a mechanics of materials course in an inverted format for the past two years. In this format, students learn the concepts outside of class, using a textbook, animations and videos developed by the authors, and work on homework either individually or in groups during the optional class time. Students take eight multiple-choice exams and a final exam that is common to both the inverted sections and the more traditional lecture-based sections. Homework in the inverted sections is assigned but not graded. The in-class exams are given in a computer lab, and each student receives an individualized set of questions. Over 1200 students in 18 course sections have participated in either the inverted sections themselves or the other non-traditional sections that preceded the particular format used today. A subset of this group was compared to students in the traditional sections. No statistically significant difference between the two groups was found based on (1) performance on the common final exams or (2) course grade in a structural analysis course. The animations and videos used by students in the inverted sections are available on a class web site. There are 167 animation modules and 230 videos. The animations contain example problems and exercises. The videos are, on average, six minutes in length and cover concepts, demonstrations, problem strategies, problem solutions, and experiments. The authors use Google Analytics to track how much each piece of content is utilized. The website was accessed 46,500 times, and the content, excluding the animations, was used for a total of 12,700 hours during the past 16 months. By tracking how students perform on each multiple-choice question, the authors have developed a concept inventory with numerical rankings from the best to worst understood concepts. Combining this with how much each online resource is utilized, the authors can now target development of future course materials on the least-understood concepts and in the format most preferred by the students. An inverted teaching format would not be appropriate for every college course, but it has helped the authors begin looking at their mechanics of materials course in a more scientific, data-driven manner

    Replication of Eye-Bars and Measurement of Losses in Cross Section Due to Corrosion

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    Recent availability of high pressure water blasters made it possible to remove rust accumulated between the eye-bars near pin connections on the Central Bridge (Figure 1) over the Ohio River at Newport. Previously, they had never been thoroughly cleaned. Cleaning of two connections on a trial basis enabled an inspection between the bars. It was apparent then that the deterioration was critical enough to necessitate examination of the several bar groups and to accurately measure their least cross sections. The Research Division undertook the task of replicating and measuring the bars. Figures 2 and 3 show one set of bars before and after cleaning. Considerable difficulty was encountered in making moldings or impressions because the space between the two center bars, referred to here as 1, 2, 3 and 4 (Figure 4), varied between one-quarter and one-half inch. Thin sheet metal forms (Figure 5) were used to fit around each section. These forms were then tied in place (Figure 6) and sealed around the edges with paraffin to prevent liquid leakage. A two-component compound, referred to as Sika-Flex, was used to rill these forms and provide a negative molding. Sika-Flex is a liquid joint filler which hardens into a rubbery type of material after mixing --- thereby retaining the exact shape of the bar sections after removal. Wire mesh was used inside the forms around the bars to prevent stretching or deformation of the Sika-Flex mold. Figures 7 and 8 show the forms installed. The forms were removed after several hours of curing and taken to the laboratory where hydrostone was used to make an exact positive casting of the bar sections (Figure 9). Thereafter, each of these replicates was measured at three or four places where the least section was thought to be. A contour gauge was used to transfer these cross sections onto paper and then the area was measured with a planimeter. This method is believed to be reasonably accurate. The percent loss of section in each bar was calculated in reference to the original section taken from calculations made previously by the Maintenance Division. A key for identifying the bars as listed is provided in Figure 10. Attached are copies of the measured sections of the respective bars listed in Table 1

    STDP in the Developing Sensory Neocortex

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    Spike timing-dependent plasticity (STDP) has been proposed as a mechanism for optimizing the tuning of neurons to sensory inputs, a process that underlies the formation of receptive field properties and associative memories. The properties of STDP must adjust during development to enable neurons to optimally tune their selectivity for environmental stimuli, but these changes are poorly understood. Here we review the properties of STDP and how these may change during development in primary sensory cortical layers 2/3 and 4, initial sites for intracortical processing. We provide a primer discussing postnatal developmental changes in synaptic proteins and neuromodulators that are thought to influence STDP induction and expression. We propose that STDP is shaped by, but also modifies, synapses to produce refinements in neuronal responses to sensory inputs

    Application of LANDSAT to the management of Delaware's marine and wetland resources

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    The author has identified the following significant results. LANDSAT data were found to be the best source of synoptic information on the distribution of horizontal water mass discontinuities (fronts) at different portions of the tidal cycle. Distributions observed were used to improve an oil slick movement prediction model for the Delaware Bay. LANDSAT data were used to monitor the movement and dispersion of industrial acid waste material dumped over the continental shelf. A technique for assessing aqueous sediment concentration with limited ground truth was proposed

    Skylab/EREP application to ecological, geological, and oceanographic investigations of Delaware Bay

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    Skylab/EREP S190A and S190B film products were optically enhanced and visually interpreted to extract data suitable for; (1) mapping coastal land use; (2) inventorying wetlands vegetation; (3) monitoring tidal conditions; (4) observing suspended sediment patterns; (5) charting surface currents; (6) locating coastal fronts and water mass boundaries; (7) monitoring industrial and municipal waste dumps in the ocean; (8) determining the size and flow direction of river, bay and man-made discharge plumes; and (9) observing ship traffic. Film products were visually analyzed to identify and map ten land-use and vegetation categories at a scale of 1:125,000. Digital tapes from the multispectral scanner were used to prepare thematic maps of land use. Classification accuracies obtained by comparison of derived thematic maps of land-use with USGS-CARETS land-use maps in southern Delaware ranged from 44 percent to 100 percent

    Skylab/EREP application to ecological, geological, and oceanographic investigations of Delaware Bay

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    The author has identified the following significant results. Skylab/EREP S190A and S190B film products were optically enhanced and visually interpreted to extract data suitable for mapping coastal land use; inventorying wetlands vegetation; monitoring tidal conditions; observing suspended sediment patterns; charting surface currents; locating coastal fronts and water mass boundaries; monitoring industrial and municipal waste dumps in the ocean; and determining the size and flow direction of river, bay, and man-made discharge plumes. Film products were visually analyzed to identify and map ten land use and vegetation categories at a scale of 1:125,000. Thematic maps were compared with CARETS land use maps, resulting in classification accuracies of 50 to 98%. Digital tapes from S192 were used to prepare thematic land use maps. The resolutions of the S190A, S190B, and S192 systems were 20-40m, 10-20m, and 70-100m, respectively

    Seychelles, a vulnerable or resilient sids? A local perspective

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    This article analyses perceptions of residents of the Seychelles in the western Indian Ocean in relation to a long-running debate over small island developing states (SIDS) as to whether they are vulnerable or resilient. The results of data obtained from 25 key informant interviews and 70 household surveys conducted in 2013 showed that respondents perceived their country to be both vulnerable and resilient. Moreover, the data revealed that the relationship between vulnerability and resilience was complex, and that five interpretations of that relationship were evident: conflict, compromise, complementarity, symbiosis and transformation. Also, the conceptual distance between the two terms vulnerability and resilience was shown to be closer than may be commonly assumed. Finally, the paper questions whether the debate over vulnerability versus resilience is rightly confined to SIDS or could be equally applied to other states

    Application of ecological, geological and oceanographic ERTS-1 imagery to Delaware's coastal resources management

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    The author has identified the following significant results. Data from twelve successful ERTS-1 passes over Delaware Bay have been analyzed with special emphasis on coastal vegetation, land use, current circulation, water turbidity and pollution dispersion. Secchi depth, suspended sediment concentration and transmissivity as measured from helicopters and boats were correlated with ERTS-1 image radiance. Multispectral signatures of acid disposal plumes, sediment plumes and slick were investigated. Ten vegetative cover and water discrimination classes were selected for mapping: (1) forest-land; (2) Phragmites communis; (3) Spartina patens and Distichlis spicata; (4) Spartina alterniflora; (5) cropland; (6) plowed cropland; (7) sand and bare sandy soil; (8) bare mud; (9) deep water; and (10) sediment-laden and shallow water. Canonical analysis predicted good classification accuracies for most categories. The actual classification accuracies were very close to the predicted values with 8 of 10 categories classified with greater than 90% accuracy indicating that representative training sets had been selected
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