scholarly journals SEGMENTATION OF WATER BODY GIVEN PROBABILITY OF OCCURRENCE OF WIND DIRECTION BY CIRCULAR OR ELLIPTIC DISTRIBUTION

2017 ◽  
pp. 6 ◽  
Author(s):  
Masumi Serizawa ◽  
Takaaki Uda ◽  
Shiho Miyahara
Keyword(s):  
Wind Direction ◽  
Water Body ◽  
Principal Axis ◽  
Wind Waves ◽  
Sand Transport ◽  
Large Aspect Ratio ◽  
Probability Of Occurrence ◽  
Sheltering Effect ◽  
Transport Flux ◽  
Over Time

In a slender water body with a large aspect ratio, the angle of wind waves relative to the direction normal to the shoreline may exceed 45°, resulting in the emergence of cuspate forelands and the segmentation of a lake, because the fetch distance along the principal axis becomes large. The BG model was used to predict the segmentation of a rectangular water body by wind waves when the probability of occurrence of wind direction is given by a circular or elliptic distribution. The changes in wave field and sand transport flux over time were calculated to investigate the wave-sheltering effect of the cuspate forelands. A rectangular lake segmented into circular or elliptic lake, when the probability of occurrence of wind direction is given by a circular or elliptic distribution, respectively.

scholarly journals NUMERICAL SIMULATION OF THREE-DIMENSIONAL SEGMENTATION OF ELONGATED WATER BODY USING BG MODEL

2012 ◽  
Vol 1 (33) ◽  
pp. 65 ◽  
Author(s):  
Takaaki Uda ◽  
Masumi Serizawa ◽  
Shiho Miyahara
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
Water Body ◽  
Principal Axis ◽  
Three Dimensional ◽  
Large Aspect Ratio ◽  
Dimensional Model ◽  
Wave Direction ◽  
Three Dimensional Model ◽  
Three Dimensional Segmentation

In a slender water body with a large aspect ratio, the angle between the direction normal to the shoreline and the wave direction exceeds 45°, resulting in the emergence of cuspate forelands and the subdivision of a lake, because wind fetch along the principal axis becomes long. In this study, the BG model (a three-dimensional model for predicting beach changes based on Bagnold’s concept) was applied to this problem. The 3-D subdivision process of a long slender water body was predicted.

scholarly journals To Protect the World’s Sand, We Need to Know How to Measure It

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Rachel Fritts
Keyword(s):  
Sand Transport ◽  
Accurate Model ◽  
Know How ◽  
New Research ◽  
Over Time

New research provides a more accurate model that coastal managers and engineers can use to account for sand transport over time.

scholarly journals Automated tracking of S. pombe spindle elongation dynamics

2020 ◽  
Author(s):  
Ana Sofía M. Uzsoy ◽  
Parsa Zareiesfandabadi ◽  
Jamie Jennings ◽  
Alexander F. Kemper ◽  
Mary Williard Elting
Keyword(s):  
Principal Axis ◽  
Model Organism ◽  
Data Sets ◽  
Mitotic Progression ◽  
Automated Tracking ◽  
Spindle Elongation ◽  
Microscopy Data ◽  
Spindle Structure ◽  
Over Time ◽  
Imagej Plugin

The mitotic spindle is a microtubule-based machine that pulls the two identical sets of chromosomes to opposite ends of the cell during cell division. The fission yeast Schizosaccharomyces pombe is an important model organism for studying mitosis due to its simple, stereotyped spindle structure and well-established genetic toolset. S. pombe spindle length is a useful metric for mitotic progression, but manually tracking spindle ends in each frame to measure spindle length over time is laborious and can limit experimental throughput. We have developed an ImageJ plugin that can automatically track S. pombe spindle length over time and replace manual or semi-automated tracking of spindle elongation dynamics. Using an algorithm that detects the principal axis of the spindle and then finds its ends, we reliably track the length and angle of the spindle as the cell divides. The plugin integrates with existing ImageJ features, exports its data for further analysis outside of ImageJ, and does not require any programming by the user. Thus, the plugin provides an accessible tool for quantification of S. pombe spindle length that will allow automatic analysis of large microscopy data sets and facilitate screening for effects of cell biological perturbations on mitotic progression.

scholarly journals Seasonal variability of hydrodynamics in the Vistula Estuary in 1994

2007 ◽  
Vol 36 (4) ◽  
Author(s):  
Małgorzata Robakiewicz
Keyword(s):  
Wind Direction ◽  
Water Body ◽  
Seasonal Variability ◽  
River Mouth ◽  
Meteorological Conditions ◽  
Field Observations ◽  
Mixing Processes ◽  
Local Conditions ◽  
Open Sea ◽  
Region Model

Seasonal variability of hydrodynamics in the Vistula Estuary in 1994The Vistula Estuary is a coastal water body boasting free connection with the open sea, where mixing processes of marine and fluvial waters are maintained by local conditions. Based on results from a hydrodynamic model, applied to represent conditions in the year 1994, and using salinity as a tracer, it was found that fluvial water has a tendency to spread westward from the river mouth. This is in contradiction with the dominant wind direction in the region. Model results confirmed field observations of specific hydrological and meteorological conditions required to transport fluvial water northward, towards the Hel Peninsula.

FPSO Transient Responses During Cyclonic Storms

2007 ◽  
Author(s):  
Dusan Curic ◽  
Yong Luo
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Wind Waves ◽  
Rapid Change ◽  
Line Tension ◽  
Green Water ◽  
Mooring Line ◽  
Sea Waves ◽  
Transient Responses ◽  
Cyclonic Storm

This paper presents the key results and conclusions of the study of FPSO transient responses in the cyclonic storm. The measured wind, wave and current data of recent cyclonic events are utilized to simulate the FPSO responses in terms of mooring loads, vessel yaw motion and relative FPSO heading to waves as it weathervanes in the wind, waves and current, input as time series. The primary objectives are to check the FPSO responses as the cyclone (eye or fringe) passes over it, causing rapid changes in the intensity and the direction of environmental loads, and to confirm the adequacy of the present mooring system design criteria. The results of the study serve as a good benchmark of the current industry standard for mooring design and address industry’s concern of the safety of FPSO platforms in the event of cyclonic storm. This study has used the hindcast data to inspect the event of a strong cyclonic storm passing over an FPSO. Despite the fact that the wind direction changes for about 140° in only one hour in the path of the cyclone eye, higher mooring line tension has not been observed due to reduced wind speed in the eye of the storm. The extreme mooring line tension is still governed by the responses in the path of cyclone fringe due to its maximum wind speed. Note that the transient analysis has shown that, during the rapid change of wind direction, the vessel can potentially be exposed to beam sea waves. Although this does not correspond with the highest tension in mooring legs, it can lead to critical green water impact.

scholarly journals Structure of the Airflow above Surface Waves

2016 ◽  
Vol 46 (5) ◽  
pp. 1377-1397 ◽  
Author(s):  
Marc P. Buckley ◽  
Fabrice Veron
Keyword(s):  
Surface Waves ◽  
Wind Waves ◽  
Quadrant Analysis ◽  
Momentum Exchange ◽  
Turbulent Structures ◽  
Mean Velocity ◽  
Law Of The Wall ◽  
Generate Surface ◽  
Turbulent Momentum ◽  
Sheltering Effect

AbstractIn recent years, much progress has been made to quantify the momentum exchange between the atmosphere and the oceans. The role of surface waves on the airflow dynamics is known to be significant, but our physical understanding remains incomplete. The authors present detailed airflow measurements taken in the laboratory for 17 different wind wave conditions with wave ages [determined by the ratio of the speed of the peak waves Cp to the air friction velocity u* (Cp/u*)] ranging from 1.4 to 66.7. For these experiments, a combined particle image velocimetry (PIV) and laser-induced fluorescence (LIF) technique was developed. Two-dimensional airflow velocity fields were obtained as low as 100 μm above the air–water interface. Temporal and spatial wave field characteristics were also obtained. When the wind stress is too weak to generate surface waves, the mean velocity profile follows the law of the wall. With waves present, turbulent structures are directly observed in the airflow, whereby low-horizontal-velocity air is ejected away from the surface and high-velocity fluid is swept downward. Quadrant analysis shows that such downward turbulent momentum flux events dominate the turbulent boundary layer. Airflow separation is observed above young wind waves (Cp/u*< 3.7), and the resulting spanwise vorticity layers detached from the surface produce intense wave-coherent turbulence. On average, the airflow over young waves (with Cp/u* = 3.7 and 6.5) is sheltered downwind of wave crests, above the height of the critical layer zc [defined by 〈u(zc)〉 = Cp]. Near the surface, the coupling of the airflow with the waves causes a reversed, upwind sheltering effect.

Seasonal Production of Hypogeal Fungal Sporocarps in a Mixed-Species Eucalypt Forest Stand in South-Eastern Australia

1993 ◽  
Vol 41 (2) ◽  
pp. 145 ◽  
Author(s):  
AW Claridge ◽  
AP Robinson ◽  
MT Tanton ◽  
RB Cunningham
Keyword(s):  
Management Practices ◽  
Morphological Characteristics ◽  
Forest Stand ◽  
Mixed Species ◽  
Probability Of Occurrence ◽  
Soil Variables ◽  
Eucalypt Forest ◽  
Eastern Australia ◽  
Physical Variables ◽  
Over Time

The seasonal production of hypogeal fungal sporoearps was monitored over an 18 month period in a catchment of mixed-species euealypt forest in East Gippsland, Vietoria. During the study, sporocarps of one Ascomycete and 25 Basidiomycete species were collected from soil quadrats sampled sequentially around the bases of eucalypt trees- Sporocarps from these species varied in their dimensions and morphological characteristics. Productivity varied from 21 000 sporocarps ha-1 to 181 000 sporocarps ha-1 or 1.8 kg ha-1 to 8.3 kg ha-1 per month. The probability of occurrence of sporocarps was, on average, greater in midslope sites on a sheltered aspect than elsewhere within the catchment. The number of sporocarps produced varied over time, with a major peak in production occurring during May (late-autumn). This peak occurred mainly within gully sites, which supported on average a greater number of sporocarps than ridge or midslope sites, but a lesser weight of sporocarps. The distribution and productivity (probability of occurrence, number and weight) of sporocarps appeared to be associated with some environmental (soil) variables, but not the physical variables (host tree), that we measured. Sporocarps of some species fruited predominantly in ridge and slope habitats, some species fruited mainly in gullies, whereas others apparently showed no preference for fruiting in ridges, slopes and gullies. Thus, in forest catchments subject to land-management practices such as logging and fire, it may be important to retain undisturbed habitat throughout the topographic sequence to conserve a diversity of hypogeal species.

scholarly journals Surface Roughness Imaging of Currents Shows Divergence and Strain in the Wind Direction

2014 ◽  
Vol 44 (8) ◽  
pp. 2153-2163 ◽  
Author(s):  
Nicolas Rascle ◽  
Bertrand Chapron ◽  
Aurélien Ponte ◽  
Fabrice Ardhuin ◽  
Patrice Klein
Keyword(s):  
Surface Roughness ◽  
Wind Direction ◽  
Wind Waves ◽  
Surface Wind ◽  
Surface Currents ◽  
Simple Method ◽  
Sea Surface Roughness ◽  
Deformation Properties ◽  
The Mean ◽  
Synthetic Aperture Radars

Abstract Images of sea surface roughness—for example, obtained by synthetic aperture radars (SAR) or by radiometers viewing areas in and around the sun glitter—at times provide clear observations of meso- and submesoscale oceanic features. Interacting with the surface wind waves, particular deformation properties of surface currents are responsible for those manifestations. Ignoring other sources of surface roughness variations, the authors limit their discussion to the mean square slope (mss) variability. This study confirms that vortical currents and currents with shear in the wind direction shall not be expressed in surface roughness images. Only divergent currents or currents with no divergence but strained in the wind direction can exhibit surface roughness signatures. More specifically, nondivergent currents might be traced with a 45° sensitivity to the wind direction. A simple method is proposed in order to interpret high-resolution roughness images, where roughness variations are proportional to ∂u/∂x + α∂υ/∂y, a linear combination of the along-wind and crosswind current gradients. The polarization parameter α depends upon the sensor look direction and the directional properties of the surface waves selected by the sensor. The use of multiple look directions or possible acquisitions with different wind directions shall thus help to retrieve surface currents from surface roughness observations.

scholarly journals FIELD MEASUREMENT OF AEOLIAN SAND FLUX USING CERAMIC SAND FLUX SENSOR UD-101 AT A SAND DUNE

2011 ◽  
Vol 1 (32) ◽  
pp. 109
Author(s):  
Keiko Udo ◽  
Junaidi Junaidi ◽  
Shin-ichi Aoki ◽  
Shota Mitsushio ◽  
Shigeru Kato ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Sand Dune ◽  
Field Measurements ◽  
Sand Transport ◽  
Aeolian Sand ◽  
Aeolian Sand Transport ◽  
Charnock Constant ◽  
Sand Flux ◽  
Transport Flux ◽  
Flux Sensor

This study conducted field observations in terms of the number of blown sand impacts and wind velocity at an open ocean beach in Japan, in order to investigate characteristics of the aeolian sand transport flux over a sand dune slope. Charnock constant of a roughness length equation calculated from wind velocity data had a larger value over the slope compared to over a flat. Furthermore, the aeolian flux over the slope tended to be larger than that over the flat. Characteristics of the Charnock constant and the aeolian flux over the flat and the slope were demonstrated from the field measurements.

Evaluation of the Factor Structure Underlying Two Measures of Hardiness

Assessment ◽  
1996 ◽  
Vol 3 (4) ◽  
pp. 423-435 ◽  
Author(s):  
Lois A. Benishek
Keyword(s):  
Factor Structure ◽  
Principal Axis ◽  
Factor Analyses ◽  
Confirmatory Factor Analyses ◽  
University Employees ◽  
Psychological Wellness ◽  
Confirmatory Factor ◽  
Two Measures ◽  
Over Time ◽  
Principal Axis Factor

This study critically evaluated the factor structure underlying two measures of hardiness. Hardiness was conceptualized by Kobasa as consisting of three factors: commitment, control, and challenge. Over time, however, one- to four-factor solutions have been identified, depending on the measures used and the population studied. A sample of 183 adult university employees completed the Personal Views Survey (PVS) and the Revised Hardiness Scale (RHS). Neither principal axis factor analyses nor confirmatory factor analyses supported Kobasa's conceptualization of hardiness. The findings of this study highlight the importance of reevaluating how hardiness is conceptualized and revising its measures before continuing to investigate each factor's effect on physical and psychological wellness.

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