Prediction of continental shelf sediment transport using a theoretical model of the wave-current boundary layer

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1987This thesis presents an application of the Grant-Madsen-Glenn bottom boundary layer model (Grant and Madsen, 1979; Glenn and Grant, 1987) to predictions of sediment transport on the continental shelf. The analysis is a two-stage process. Via numerical experiment, we explore the sensitivity of sediment transport to variations in model parameters and assumptions. A notable result is the enhancement of suspended sediment stratification due to wave boundary layer effects. When sediment stratification is neglected under conditions of large wave bottom velocities, concentration predictions can be more than an order of magnitude higher than any observed during storm conditions on the continental shelf. A number of limitations to application emerged from the analysis. Solutions to the stratified model are not uniquely determined under a number of cases of interest, potentially leading to gross inaccuracies in the prediction of sediment load and transport. Load and sediment transport in the outer Ekman Layer, beyond the region of emphasis for the model, can be as large or larger than the near-bottom estimates in some cases; such results suggest directions for improvements in the theoretical model. In the second step of the analysis, we test the ability of the model to make predictions of net sediment transport that are consistent with observed sediment depositional patterns. Data from the Mid-Atlantic Bight and the Northern California coast are used to define reasonable model input to represent conditions on two different types of shelves. In these examples, the results show how the intensification of wave bottom velocities with decreasing depth can introduce net transport over a region. The patterns of erosion/deposition are shown to be strongly influenced by sediment stratification and moveable bed roughness. Also predicted by the applications is a rapid winnowing out of fine grain size components when there is even a small variation of bed grain size texture in the along-flow direction

Growth and Characterization of Nickel Catalyzed Gallium Oxide Nanowires on Sapphire Substrate

Beta gallium oxide (-Ga2O3) nanowires (NWs) were synthesized via chemical vapor deposition in argon atmosphere using gallium as a precursor and sapphire substrate coated with ultra thin film of nickel (Ni). In this report, we report the growth of -Ga2O3 NWs as a function of deposition time. The structure and morphology of grown NWs were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The results revealed that single crystal growth of the NWs and their crystallinity improved with the increase in the deposition time. The diameter of -Ga2O3 NWs varied in the range between 40-80 nm and their length was observed up to many micrometers. The optical property of NWs was determined using UV-visible spectrophotometer and the bandgap of -Ga2O3 NWs was found to be about 4.30 eV. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3099

CLINICAL EFFICACY OF UDVARTANA WITH LEKHANA BASTI IN HYPERCHOLESTEROLEMIA

Now a day, due to increase in industrialized population include a sedentary lifestyle and a diet characterized by the excessive consumption of saturated fats, trans fatty acids and cholesterol which tends to increase blood cholesterol levels. Raised total cholesterol is a major cause of disease burden in both the developed and developing world as a risk factor for Ischemic heart disease and stroke. In Ayurveda, this condition can be considered under Santarpanotthavyadhi.  Due to Santarpanothanidanas there will be increase in the Pichilla and Snehagunas which in turn causes Ama, if further same nidanas are continued leads to Madhuratara of Ama and Annarasa causes the circulation of increased Medaie: Shareera Anukraman Atisnehan Medo Janayati.  To combat this condition Acharyas have mentioned about VatagnaAnnapana, Ruksha- Ushna i.e., Ruksha Udvartana, Lekhana Basti etc lines of treatment.  Hence this study was taken up to see the efficacy of the treatment protocol mentioned for the better management. It was an open label clinical study done on 10 patients.  Patients were subjected to Sarvanga Udvartana with Kolakulatthadichurna and Lekhanabasti for a period of fifteen days. In the present study, the effect of the treatment has shown statistically Highly Significant   (p<0.01) results on Serum Cholesterol and LDL.  As the study was conducted to know the combined effect of Bahyaupakrama along with the Lekhanabasti, the usefulness of individual Upakrama found limited.  So probably administration of these upakramas in single dimension one after the other along with proper diet and physical exercise in frequent intervals may yield good results

Modeling human observer detection in undersampled magnetic resonance imaging (MRI) reconstruction with total variation and wavelet sparsity regularization

Purpose: Task-based assessment of image quality in undersampled magnetic resonance imaging provides a way of evaluating the impact of regularization on task performance. In this work, we evaluated the effect of total variation (TV) and wavelet regularization on human detection of signals with a varying background and validated a model observer in predicting human performance. Approach: Human observer studies used two-alternative forced choice (2-AFC) trials with a small signal known exactly task but with varying backgrounds for fluid-attenuated inversion recovery images reconstructed from undersampled multi-coil data. We used a 3.48 undersampling factor with TV and a wavelet sparsity constraints. The sparse difference-of-Gaussians (S-DOG) observer with internal noise was used to model human observer detection. Results: We observed a trend that the human observer detection performance remained fairly constant for a broad range of values in the regularization parameter before decreasing at large values. A similar result was found for the normalized ensemble root mean squared error. Without changing the internal noise, the model observer tracked the performance of the human observers as the regularization was increased but overestimated the PC for large amounts of regularization for TV and wavelet sparsity, as well as the combination of both parameters. Conclusions: For the task we studied, the S-DOG observer was able to reasonably predict human performance with both TV and wavelet sparsity regularizers over a broad range of regularization parameters. We observed a trend that task performance remained fairly constant for a range of regularization parameters before decreasing for large amounts of regularization

Coastal sediment transport, Popponesset Beach, MA

Pathways and rates of near-bed sediment transport near Popponesset Beach, MA ., were calculated using several distinct techniques. For the nearshore platform, sand transport in the form of sand waves was determined from vertical aerial photography spanning periods of four decades. In addition, calculations based on theoretical and empirical equations for near-bed sediment transport were made using field measurements of wind waves and tidal currents. Net sediment transport to the southwest inferred from these two techniques differed by about a factor of five. The higher net transport rate predicted in the aerial photographic method is a result of lack of wave measurements during storm conditions. Storm waves increase the net transport through a local increase in bed shear stress. Net transport to the southwest across the platform is between 700 and 3300 m3/yr. Littoral sand transport along Popponesset Beach was calculated from one month of directional wave measurements, extrapolated to a yearly value using long-term meteorological observations. Littoral transport from these calculations is 10,000 m3/yr to the northeast, opposite the sense of alongshore transport in the shallow nearshore. Patterns of shoreline change are discussed from a historical perspective, and using the transport calculations discussed above. Several management alternatives for coping with predicted shoreline change are presented for consideration by the Town of Mashpee.Funding was provided by the Town of Mashpee, a Community Assistance Grant was provided through the Coastal Zone Management Program, a Sea Grant Program Grant NA80AA-D-00077(RB-40) and support from ALCOA Foundation

A COSTLESS VIRTUAL RATING METHOD FOR VISUAL SEARCH

Content-basis image retrieval is important option to prevail within the difficulties of previous works and will be offering attracted an excellent concentration in past decades. The models according to graph-based ranking were mostly analysed and extensively functional in recovery area. Within our work we concentrate on the novel additionally to efficient graph-based model for content based image retrieval, produced for out-of-sample recovery on extensive databases. We advise a scalable graph-based ranking representation referred to as effective Manifold Ranking, which address flaws of Manifold Ranking from two most critical viewpoints for example scalable graph construction additionally to effective ranking computation. We concentrate on a famous graph-based model known Manifold Ranking this is often a well-known graph-based ranking representation that ranks data samples tightly associated with intrinsic geometrical structure uncovered obtaining a massive data. The suggested model includes two separate stages similar to an offline stage for structuring of ranking model by getting a web-based stage for controlling of recent query. While using the suggested system, we're outfitted to deal with database getting countless images and perform online retrieval within the short instance