Characterization of Patches Along Transects Using High-Resolution 70-kHz Integrated Acoustic Data

1989 ◽  
Vol 46 (12) ◽  
pp. 2056-2064 ◽  
Author(s):  
R. W. Nero ◽  
J. J. Magnuson
Keyword(s):  
North Carolina ◽  
High Resolution ◽  
Gulf Stream ◽  
Window Size ◽  
Recognition Algorithm ◽  
Pass Filter ◽  
Acoustic Data ◽  
Cape Hatteras ◽  
High Pass

A patch recognition algorithm was applied to high-resolution (1 m vertical and 25 m horizontal) daytime sonar date collected from a 20-km-length transect to a depth of 200 m. The transect was oriented perpendicular to the Gulf Stream frontal zone, 105 km east–northeast ENE of Cape Hatteras, North Carolina, on August 8 1985. An adaptive high-pass filter was used to identify patches of high-intensity echo strengths. For a broad based averaging "window size" of 13 m deep by 1.4 km long and an echo strength threshold of 1.4 × integrated echo units patches resemble fine-scale features of the original echogram. A discrimination of patches using sonar statistics from within the patches gave good separation of slope water patches from patches belonging to four other water masses Slope water patches were characteristically small and of low mean scattering. Large but infrequent targets were present In the Gulf Stream, by contrast, patches contained more uniformly distributed targets with a higher mean scattering The observed correlation between echo patches, biological structures, and oceanographic features suggests that the measurement of echo statistics and our patch recognition techniques produce biologically meaningful parameters.

Profile Characterization of Manufactured Surfaces Using Random Function Excursion Technique, Part 2: Application

1975 ◽  
Vol 97 (1) ◽  
pp. 196-202 ◽  
Author(s):  
M. O. M. Osman ◽  
T. S. Sankar
Keyword(s):  
Machined Surface ◽  
Pass Filter ◽  
Measuring Device ◽  
Surface Parameters ◽  
Actual Surface ◽  
Surface Measurements ◽  
On Line ◽  
Surface Profiles ◽  
High Pass

In Part 1 of this paper an analytical procedure based on the theory of random excursions was described to characterize the texture of a machined surface in terms of four new parameters. In this part a number of experimental results are presented to justify the validity of the proposed surface parameters. Surface measurements were carried out on ten differently machined surfaces using a specially equipped measuring device with a direct cable link to a hybrid computer. The theoretically computed surface parameters compare favorably with the measurements made on the actual surface profiles that were recorded experimentally. One of the advantages of the surface parameters presented in this paper is that they correspond directly to the mechanical properties of the machined component and hence can be used readily in specifications. Further, the results of this paper show that i) the sampling length is essentially a high-pass filter with geometrically defined characteristics, and ii) the crest and valley excursion parameters are adaptable for both “on-line” and “off-line” surface evaluation. The method presented is well-suited for application to computer-aided manufacturing without any special modifications. Based on this investigation, a proposal for a mechanical stylus system for “online” surface measurements is also made.

The Combined Effects of Gulf Stream–Induced Baroclinicity and Upper-Level Vorticity on U.S. East Coast Extratropical Cyclogenesis

2005 ◽  
Vol 133 (8) ◽  
pp. 2494-2501 ◽  
Author(s):  
Neil A. Jacobs ◽  
Gary M. Lackmann ◽  
Sethu Raman
Keyword(s):  
North Carolina ◽  
Gulf Stream ◽  
Additional Data ◽  
Large Fraction ◽  
Coastal Region ◽  
Western Boundary ◽  
Absolute Vorticity ◽  
Surface Cyclone ◽  
Cape Hatteras ◽  
Upper Level

Abstract The Atlantic Surface Cyclone Intensification Index (ASCII) is a forecast index that quantifies the strength of low-level baroclinicity in the coastal region of the Carolinas. It is based on the gradient between the coldest 24-h average air temperature at Cape Hatteras and Wilmington, North Carolina, and the temperature at the western boundary of the Gulf Stream. The resulting prestorm baroclinic index (PSBI) is used to forecast the probability that a cyclone in the domain will exhibit rapid cyclogenesis. The initial ASCII study covered the years 1982–90. This dataset was recently expanded to cover the years 1991–2002, which doubled the number of cyclone events in the sample. These additional data provide similar position and slope of the linear regression fits to the previous values, and explain as much as 30% of the variance in cyclone deepening rate. Despite operational value, the neglect of upper-tropospheric forcing as a predictor in the original ASCII formulation precludes explanation of a large fraction of the deepening rate variance. Here, a modified index is derived in which an approximate measure of upper-level forcing is included. The 1991–2002 cyclone events were separated into bins of “strongly forced,” “moderately forced,” and “weakly forced” based on the strength of the nearest upstream maximum of 500-mb absolute vorticity associated with the surface low. This separation method reduced the scatter and further isolated the contributions of surface forcing versus upper-level forcing on extratropical cyclogenesis. Results of the combined upper-level index and surface PSBI demonstrate that as much as 74% of the deepening rate variance can be explained for cases with stronger upper-level forcing.

Hydrokinetic Energy Resource Assessment of the Gulf Stream Near Cape Hatteras, North Carolina

2014 ◽  
Author(s):  
Asif Kabir ◽  
Ivan J. Lemongo ◽  
Arturo Fernandez
Keyword(s):  
North Carolina ◽  
Gulf Stream ◽  
Energy Resource ◽  
Resource Assessment ◽  
Ocean Model ◽  
Likelihood Method ◽  
Ocean Current ◽  
Hydrokinetic Energy ◽  
Cape Hatteras ◽  
Promising Source

The Gulf Stream near the coasts of North Carolina is considered a promising source of hydrokinetic energy. A statistical analysis is conducted to assess the energy available for extraction in this region. Weibull distribution is used as the Probability Density Function (PDF) for this purpose. The ocean current velocity data are collected from the ‘HYbrid Coordinate Ocean Model (HYCOM)’. The data are collected at a depth of 20 m from the sea surface which is considered a good position for energy extraction. The Weibull parameters from the analysis are calculated using the maximum likelihood method. The direction of the ocean current was found to be mostly uniform in this region. The theoretical power density of this region was estimated to be more than 275 W/m2 around 70% of the time and exceeded 2000 W/m2 around 10% of the time.

scholarly journals Surface Reflectance: An Optical Method for Multiscale Curvature Characterization of Wear on Ceramic–Metal Composites

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1024 ◽  
Author(s):  
Julie Lemesle ◽  
Frederic Robache ◽  
Gaetan Le Goic ◽  
Alamin Mansouri ◽  
Christopher A. Brown ◽  
...  
Keyword(s):  
Strong Correlation ◽  
Band Pass Filter ◽  
Metal Composites ◽  
Pass Filter ◽  
Surface Gradient ◽  
Light Reflectance ◽  
Band Pass ◽  
First Time ◽  
High Pass

Surface gradient characterization by light reflectance (SGCLR) is used for the first time for multiscale curvature calculations and discrimination of worn surfaces on six damaged ceramic–metal composites. Measurements are made using reflectance transformation imaging (RTI). Slope and curvature maps, generated from RTI, are analyzed instead of heights. From multiscale decompositions, bootstrapping, and analysis of variance (ANOVA), a strong correlation (R² = 0.90) is found between the density of furrows of Mehlum curvatures, with a band pass filter at 5.4 µm, present in ceramic grains and their mechanical properties. A strong correlation is found between the mean curvatures of the metal and the ceramics, with a high pass filter at 1286 µm.

Gulf stream marine hydrokinetic energy resource characterization off Cape Hatteras, North Carolina USA

2016 ◽  
Author(s):  
Ruoying He ◽  
John Bane ◽  
Mike Muglia ◽  
Sara Haines ◽  
Caroline Lowcher ◽  
...  
Keyword(s):  
North Carolina ◽  
Gulf Stream ◽  
Energy Resource ◽  
Hydrokinetic Energy ◽  
Cape Hatteras ◽  
Marine Hydrokinetic

Internal gravity wave detection in high-resolution model data

2021 ◽  
Author(s):  
Zuzana Procházková ◽  
Christopher Kruse ◽  
Aleš Kuchař ◽  
Petr Pišoft ◽  
Petr Šácha
Keyword(s):  
High Resolution ◽  
Climate Models ◽  
Internal Gravity Waves ◽  
Horizontal Resolution ◽  
Energy Budgets ◽  
Filter Method ◽  
Pass Filter ◽  
Filtering Method ◽  
High Pass Filter ◽  
High Pass

<p>Internal gravity waves (GWs) are ubiquitous in the atmosphere, affecting momentum and energy budgets. However, our understanding of GW effects is still incomplete. As they act on various spatial and temporal scales, global observations of GWs face several difficulties and their parametrizations in climate models employ numerous simplifications and are only poorly constrained. Also, GW analyses in high-resolution datasets contain some uncertainty that we aim to quantify and minimize in our research. We study the uncertainty for a Gaussian high-pass filter method applied on a WRF simulation with horizontal resolution of 3 km covering a domain around the Drake Passage and ranging up to the altitude of 80 km. We show that the momentum flux and drag estimates evaluated by the filtering method are sensitive to the value of a cut-off parameter, especially the horizontal drag components. This motivates us to formulate a new, modified filtering method for GW detection that sets an optimal value of the cut-off parameter at each step based on the spectral information – the method uses a wavelength identified in the horizontal spectrum of kinetic energy. Finally, we note that the type of a response function in the high-pass filter definition also impacts the resulting estimates.</p>

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