Characteristics of Water Velocity Variation According to the Sluice and Outflow Direction of Dong-Sam Seawater Stream

2021 ◽  
Vol 114 (sp1) ◽  
Author(s):  
Seunghwan Jin ◽  
Dongha Kim ◽  
Hak Soo Lim ◽  
Hee Jun Lee
Keyword(s):  
Water Velocity ◽  
Velocity Variation

scholarly journals Potential phenotypic plasticity within Simulium nigrimanum Macquart, 1838 (Diptera: Simuliidae) larvae

2021 ◽  
Vol 26 (2) ◽  
Author(s):  
Ronaldo Figueiró ◽  
Anderson Calvet ◽  
Leonardo Henrique Gil-Azevedo ◽  
Ricardo Ferreira Monteiro ◽  
Marilza Maia-Herzog
Keyword(s):  
Body Size ◽  
Phenotypic Plasticity ◽  
Size Variation ◽  
Water Velocity ◽  
Velocity Variation ◽  
Water Current ◽  
Black Fly ◽  
Disk Diameter ◽  
Water Current Velocity ◽  
Fly Larvae

Black fly larvae (Diptera: Simuliidae) are suspension filter-feeders which strongly depend on water velocity for proper feeding. Black fly species feature different microhabitat preferences. Studies of Holarctic black fly larvae revealed their phenotypic plasticity in response to water current velocity variation, but such studies have been rarely undertaken with Neotropical black flies. The current work presents results on the phenotypic plasticity of the black fly species Simulium nigrimanum Macquart. Twelve last instar larvae, sampled from the Brazilian Cerrado, were photographed under a stereoscopic microscope and measured using the CMEIAS Image tool software. Linear regressions with water velocity as the independent variable were performed, indicating that while body size and anal disk diameter correlated positively with water velocity, labral fan length correlated negatively. The observed relationships between water velocity and labral fan length and anal disk diameter were consistent with the literature, while the pattern of body size variation partially corroborated previous studies. The present work results suggest that potential phenotypic plasticity can be observed in black fly larvae within one population distributed in different microhabitats of the same stream section, as opposed toprevious reports implying that such variation is only found among population from different streams.

The influence of sea water velocity variation on seismic traveltimes, ray paths, and amplitude

2012 ◽  
Vol 9 (3) ◽  
pp. 319-325 ◽  
Author(s):  
Fu-Xing Han ◽  
Jian-Guo Sun ◽  
Kun Wang
Keyword(s):  
Sea Water ◽  
Water Velocity ◽  
Velocity Variation ◽  
Ray Paths

Post-Hurricane Michael damage assessment using ADCIRC storm surge hindcast, image classification, and LiDAR

Shore & Beach ◽  
2019 ◽  
pp. 3-14 ◽  
Author(s):  
Joshua Davis ◽  
Diana Mitsova ◽  
Tynon Briggs ◽  
Tiffany Briggs
Keyword(s):  
Wave Energy ◽  
Field Studies ◽  
Feedback Mechanism ◽  
Water Velocity ◽  
Airborne Lidar ◽  
Storm Events ◽  
Magnetic Current ◽  
Coastal Mapping ◽  
Electro Magnetic

Wave forcing from hurricanes, nor’easters, and energetic storms can cause erosion of the berm and beach face resulting in increased vulnerability of dunes and coastal infrastructure. LIDAR or other surveying techniques have quantified post-event morphology, but there is a lack of in situ hydrodynamic and morphodynamic measurements during extreme storm events. Two field studies were conducted in March 2018 and April 2019 at Bethany Beach, Delaware, where in situ hydrodynamic and morphodynamic measurements were made during a nor’easter (Nor’easter Riley) and an energetic storm (Easter Eve Storm). An array of sensors to measure water velocity, water depth, water elevation and bed elevation were mounted to scaffold pipes and deployed in a single cross-shore transect. Water velocity was measured using an electro-magnetic current meter while water and bed elevations were measured using an acoustic distance meter along with an algorithm to differentiate between the water and bed during swash processes. GPS profiles of the beach face were measured during every day-time low tide throughout the storm events. Both accretion and erosion were measured at different cross-shore positions and at different times during the storm events. Morphodynamic change along the back-beach was found to be related to berm erosion, suggesting an important morphologic feedback mechanism. Accumulated wave energy and wave energy flux per unit area between Nor’easter Riley and a recent mid-Atlantic hurricane (Hurricane Dorian) were calculated and compared. Coastal Observations: JALBTCX/NCMP emergency-response airborne Lidar coastal mapping & quick response data products for 2016/2017/2018 hurricane impact assessments

Velocity Variation Over Time for NACO Rounds.

1996 ◽  
Author(s):  
Susan T. Peters
Keyword(s):  
Velocity Variation ◽  
Over Time

scholarly journals Anomalous azimuthal variations with 360° periodicity of Rayleigh phase velocities observed in Scandinavia

2020 ◽  
Vol 224 (3) ◽  
pp. 1684-1704
Author(s):  
Alexandra Mauerberger ◽  
Valérie Maupin ◽  
Ólafur Gudmundsson ◽  
Frederik Tilmann
Keyword(s):  
Seismic Anisotropy ◽  
Broad Band ◽  
Shear Velocity ◽  
Velocity Variation ◽  
The South ◽  
Study Region ◽  
Lithospheric Thickness ◽  
Phase Velocities ◽  
The North ◽  
Southern Norway

SUMMARY We use the recently deployed ScanArray network of broad-band stations covering most of Norway and Sweden as well as parts of Finland to analyse the propagation of Rayleigh waves in Scandinavia. Applying an array beamforming technique to teleseismic records from ScanArray and permanent stations in the study region, in total 159 stations with a typical station distance of about 70 km, we obtain phase velocities for three subregions, which collectively cover most of Scandinavia (excluding southern Norway). The average phase dispersion curves are similar for all three subregions. They resemble the dispersion previously observed for the South Baltic craton and are about 1 per cent slower than the North Baltic shield phase velocities for periods between 40 and 80 s. However, a remarkable sin(1θ) phase velocity variation with azimuth is observed for periods >35 s with a 5 per cent deviation between the maximum and minimum velocities, more than the overall lateral variation in average velocity. Such a variation, which is incompatible with seismic anisotropy, occurs in northern Scandinavia and southern Norway/Sweden but not in the central study area. The maximum and minimum velocities were measured for backazimuths of 120° and 300°, respectively. These directions are perpendicular to a step in the lithosphere–asthenosphere boundary (LAB) inferred by previous studies in southern Norway/Sweden, suggesting a relation to large lithospheric heterogeneity. In order to test this hypothesis, we carried out 2-D full-waveform modeling of Rayleigh wave propagation in synthetic models which incorporate a steep gradient in the LAB in combination with a pronounced reduction in the shear velocity below the LAB. This setup reproduces the observations qualitatively, and results in higher phase velocities for propagation in the direction of shallowing LAB, and lower ones for propagation in the direction of deepening LAB, probably due to the interference of forward scattered and reflected surface wave energy with the fundamental mode. Therefore, the reduction in lithospheric thickness towards southern Norway in the south, and towards the Atlantic ocean in the north provide a plausible explanation for the observed azimuthal variations.

Analytical predictor–corrector entry guidance for hypersonic gliding vehicles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Huatao Chen ◽  
Kun Zhao ◽  
Juan L.G. Guirao ◽  
Dengqing Cao
Keyword(s):  
Feedback Control ◽  
Velocity Variation ◽  
Analytical Relation ◽  
Aerodynamic Load ◽  
Quasi Equilibrium ◽  
Bank Angle ◽  
Entry Guidance ◽  
Guidance Algorithm ◽  
Predictor Corrector ◽  
Guidance Problem

AbstractFor the entry guidance problem of hypersonic gliding vehicles (HGVs), an analytical predictor–corrector guidance method based on feedback control of bank angle is proposed. First, the relative functions between the velocity, bank angle and range-to-go are deduced, and then, the analytical relation is introduced into the predictor–corrector algorithm, which is used to replace the traditional method to predict the range-to-go via numerical integration. To eliminate the phugoid trajectory oscillation, a method for adding the aerodynamic load feedback into the control loop of the bank angle is proposed. According to the quasi-equilibrium gliding condition, the function of the quasi-equilibrium glide load along with the velocity variation is derived. For each guidance period, the deviation between the real-time load and the quasi-equilibrium gliding load is revised to obtain a smooth reentry trajectory. The simulation results indicate that the guidance algorithm can adapt to the mission requirements of different downranges, and it also has the ability to guide the vehicle to carry out a large range of lateral maneuvers. The feedback control law of the bank angle effectively eliminates the phugoid trajectory oscillation and guides the vehicle to complete a smooth reentry flight. The Monte Carlo test indicated that the guidance precision and robustness are good.

scholarly journals Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy

2021 ◽  
Vol 13 (12) ◽  
pp. 2293
Author(s):  
Marina Amadori ◽  
Virginia Zamparelli ◽  
Giacomo De Carolis ◽  
Gianfranco Fornaro ◽  
Marco Toffolon ◽  
...  
Keyword(s):  
Surface Water ◽  
Wind Waves ◽  
Test Site ◽  
Water Velocity ◽  
Surface Velocity ◽  
Medium Size ◽  
Small Scale ◽  
Lake Garda ◽  
Marine Applications

The SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-size lakes. ENVISAT images of the test site (Lake Garda) are processed and the Doppler Centroid Anomaly technique is adopted. The resulting surface velocity maps are compared with the outputs of a hydrodynamic model specifically validated for the case study. Thermal images from MODIS Terra are used in support of the modeling results. The surface velocity retrieved from SAR is found to overestimate the numerical results and the existence of a bias is investigated. In marine applications, such bias is traditionally removed through Geophysical Model Functions (GMFs) by ascribing it to a fully developed wind waves spectrum. We found that such an assumption is not supported in our case study, due to the small-scale variations of topography and wind. The role of wind intensity and duration on the results from SAR is evaluated, and the inclusion of lake bathymetry and the SAR backscatter gradient is recommended for the future development of GMFs suitable for lake environments.

scholarly journals Assessment of Steady and Unsteady Friction Models in the Draining Processes of Hydraulic Installations

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1888
Author(s):  
Óscar E. Coronado-Hernández ◽  
Ivan Derpich ◽  
Vicente S. Fuertes-Miquel ◽  
Jairo R. Coronado-Hernández ◽  
Gustavo Gatica
Keyword(s):  
Mathematical Model ◽  
Turbulent Flow ◽  
Water Velocity ◽  
Experimental Facility ◽  
Governing Equations ◽  
Pressure Oscillations ◽  
Air Pocket ◽  
Friction Models ◽  
The Mathematical Model

The study of draining processes without admitting air has been conducted using only steady friction formulations in the implementation of governing equations. However, this hydraulic event involves transitions from laminar to turbulent flow, and vice versa, because of the changes in water velocity. In this sense, this research improves the current mathematical model considering unsteady friction models. An experimental facility composed by a 4.36 m long methacrylate pipe was configured, and measurements of air pocket pressure oscillations were recorded. The mathematical model was performed using steady and unsteady friction models. Comparisons between measured and computed air pocket pressure patterns indicated that unsteady friction models slightly improve the results compared to steady friction models.

Accurate Simulation of the Four Modes of Post-Die Extrudate Shape Distortion

2021 ◽  
Vol 36 (1) ◽  
pp. 69-78
Author(s):  
M. Gupta
Keyword(s):  
Layer Structure ◽  
Die Design ◽  
Velocity Variation ◽  
Shape Distortion ◽  
Exit Velocity ◽  
Extrusion Die ◽  
Combined Flow ◽  
Extruded Product ◽  
Simulation Results ◽  
Extrudate Distortion

Abstract A combined flow, thermal and structural analysis is employed to simulate post-die extrudate distortion in different profile dies. All four factors which can cause extrudate distortion, namely, nonuniform exit velocity distribution, extrudate shrinkage, extrudate draw down, and deformed shape of the calibrator or sizer profile, are simulated. To analyze the effect of exit velocity variation on extrudate distortion, the parameterized geometry of a simple profile die is optimized using an extrusion die optimization software. The simulation results presented for a bi-layer profile die successfully demonstrate how gradually changing profile shape in successive calibrators/sizers can be used to simplify the die design for extrusion of complex profiles. The predicted extrudate shape and layer structure for the bi-layer die are found to accurately match with those in the extruded product.

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