scholarly journals Hydraulic scale modelling of the rating curve for a gauging station with challenging geometry

2019 ◽  
Vol 50 (3) ◽  
pp. 825-836 ◽  
Author(s):  
Øyvind Pedersen ◽  
Jochen Aberle ◽  
Nils Rüther
Keyword(s):  
Complex Geometry ◽  
Field Measurements ◽  
Numerical Control ◽  
Control Technique ◽  
Scale Model ◽  
Rating Curve ◽  
Scale Modelling ◽  
High Flows ◽  
Rating Curves ◽  
Gauging Station

Abstract Direct discharge measurements during flood events can be challenging from a technical as well as from a safety point of view. Therefore, flood discharges are often estimated by extrapolating a rating curve. Extrapolations far outside the range of the directly measured discharges are common, although the associated errors can be large. In this article, a novel method to determine suitable stage measurement locations and derive rating curves using a hydraulic scale model is presented. A hydraulic scale model for a natural gauging station site is produced with a computer numerical control technique, making a detailed representation of the prototype topography and bathymetry. The site is characterized by a complex geometry, and the results of the scale model study reveal that the current location of stage measurement is not suitable for determining the rating curve for high flows. The scale model is used to identify potential locations for future stage measurements, and a flood rating curve is constructed based on field measurements for low flows and scale model data for high flows. The study shows how hydraulic scale modelling can be used to provide more reliable rating curves for large discharges and evaluate new or existing gauging stations located at sites with challenging measurement conditions.

scholarly journals Estimating uncertainties in hydraulicallymodelled rating curves for discharge time series assessment

2018 ◽  
Vol 40 ◽  
pp. 06013
Author(s):  
Valentin Mansanarez ◽  
Ida K. Westerberg ◽  
Steve W. Lyon ◽  
Norris Lam
Keyword(s):  
Time Series ◽  
Hydraulic Model ◽  
Observation Data ◽  
Rating Curve ◽  
Hydraulic Modelling ◽  
Discharge Time ◽  
High Flows ◽  
Rating Curves ◽  
Hydrometric Station ◽  
The Impact

Establishing a reliable stage-discharge (SD) rating curve for calculating discharge at a hydrological gauging station normally takes years of data collection. Estimation of high flows is particularly difficult as they occur rarely and are often difficult to gauge in practice. At a minimum, hydraulicallymodelled rating curves could be derived with as few as two concurrent SD and water-surface slope measurements at different flow conditions. This means that a reliable rating curve can, potentially, be developed much faster via hydraulic modelling than using a traditional rating curve approach based on numerous stage-discharge gaugings. In this study, we use an uncertainty framework based on Bayesian inference and hydraulic modelling for developing SD rating curves and estimating their uncertainties. The framework incorporates information from both the hydraulic configuration (bed slope, roughness, vegetation) using hydraulic modelling and the information available in the SD observation data (gaugings). Discharge time series are estimated by propagating stage records through the posterior rating curve results. Here we apply this novel framework to a Swedish hydrometric station, accounting for uncertainties in the gaugings and the parameters of the hydraulic model. The aim of this study was to assess the impact of using only three gaugings for calibrating the hydraulic model on resultant uncertainty estimations within our framework. The results were compared to prior knowledge, discharge measurements and official discharge estimations and showed the potential of hydraulically-modelled rating curves for assessing uncertainty at high and medium flows, while uncertainty at low flows remained high. Uncertainty results estimated using only three gaugings for the studied site were smaller than ±15% for medium and high flows and reduced the prior uncertainty by a factor of ten on average and were estimated with only 3 gaugings.

Exploiting Global Dynamics of a Noncontact Atomic Force Microcantilever to Enhance Its Dynamical Robustness via Numerical Control

2016 ◽  
Vol 26 (07) ◽  
pp. 1630018 ◽  
Author(s):  
Valeria Settimi ◽  
Giuseppe Rega
Keyword(s):  
Global Bifurcation ◽  
Numerical Procedure ◽  
Basins Of Attraction ◽  
Operating Conditions ◽  
Numerical Control ◽  
Control Technique ◽  
Global Dynamics ◽  
Analytical Treatment ◽  
Topological Characterization ◽  
Safe Region

A control technique exploiting the global dynamical features is applied to a reduced order model of noncontact AFM, aiming to obtain an enlargement of the system’s safe region in parameters space. The method consists of optimally modifying the shape of the system excitation by adding controlling superharmonics, to delay the occurrence of the global events (i.e. homo/heteroclinic bifurcations of some saddle) which trigger the erosion of the basins of attraction leading to loss in safety. The system’s main saddles and the bifurcations involving the relevant manifolds are detected through accurate numerical investigations, and their topological characterization allows the determination of the global event responsible for the sharp reduction in the system dynamical integrity. Since an analytical treatment is impossible in applying the control, a fully numerical procedure is implemented. Besides being effective in detecting the value of the optimal superharmonic to be added for shifting the global bifurcation to a higher value of forcing amplitude, the method also proves to succeed in delaying the drop down of the erosion profile, thus increasing the overall robustness of the system during operating conditions.

scholarly journals The physical impact of towed demersal fishing gears on soft sediments

2015 ◽  
Vol 73 (suppl_1) ◽  
pp. i5-i14 ◽  
Author(s):  
F. G. O'Neill ◽  
A. Ivanović
Keyword(s):  
Mathematical Modelling ◽  
Large Scale ◽  
Lateral Displacement ◽  
Field Measurements ◽  
Small Scale ◽  
Physical Interaction ◽  
Soft Sediments ◽  
Fishing Gears ◽  
Scale Modelling ◽  
Physical Impact

Abstract An improved understanding of the physical interaction of towed demersal fishing gears with the seabed has been developed in recent years, and there is a clearer view of the underpinning mechanical processes that lead to the modification and alteration of the benthic environment. The physical impact of these gears on soft sediments can be classified broadly as being either geotechnical or hydrodynamic in nature: penetration and piercing of the substrate, lateral displacement of sediment, and the influence of the pressure field transmitted through the sediment can be considered geotechnical, whereas the mobilization of sediment into the water column can be considered hydrodynamic. A number of experimental and numerical approaches have been used to gain better insights of these physical processes. These include small-scale modelling in towing tanks and sand channels; large-scale modelling in the field; measurements behind full-scale towed gears at sea; numerical/mathematical modelling of sediment mechanics; and numerical/mathematical modelling of hydrodynamics. Here, we will review this research, and that in associated fields, and show how it can form the basis of predictive models of the benthic impact of trawl gears.

scholarly journals Stormflow and suspended sediment routing through a small detention pond with uncertain discharge rating curves

2018 ◽  
Vol 50 (4) ◽  
pp. 1177-1188 ◽  
Author(s):  
Adam Krajewski ◽  
Kazimierz Banasik ◽  
Anna E. Sikorska
Keyword(s):  
Sediment Concentration ◽  
Rating Curve ◽  
Discharge Time ◽  
Urban Catchment ◽  
Detention Ponds ◽  
Sediment Routing ◽  
Detention Pond ◽  
Huge Impact ◽  
Rating Curves ◽  
The Impact

Abstract Ratings curves are commonly used for computing discharge time series from recorded water stages or for hydrograph and sediment graph routing through detention ponds. Numerous studies have demonstrated that these rating curves are often linked with significant uncertainty. Nevertheless, the uncertainty related to the use of these rating curves in sediment estimates has not been investigated so far. Hence, in this work, we assess the impact of using such uncertain discharge rating curves on the estimation of the pond outflow (discharge, sediment concentration and load) from a small detention pond located in a small urban catchment in Poland. Our results indicate that the uncertainty in rating curves has a huge impact on estimates of discharge and sediment fluxes in the outlet from the reservoir, wherein the uncertainty in the inlet rating curve plays a more important role than the uncertainty in the outlet rating curve. Poorly estimated rating curve(s) may thus lead to serious errors and biased conclusions in the estimates and designs of detention ponds. To reduce this uncertainty, more efforts should be made to construct the rating curves at the pond inlet and to gather more data in extreme conditions.

Prototype Support Structure for Seabed Mounted Tidal Current Turbines

2005 ◽  
Vol 219 (4) ◽  
pp. 173-183 ◽  
Author(s):  
A Owen ◽  
I G Bryden
Keyword(s):  
Steel Structure ◽  
Field Measurements ◽  
Model Fit ◽  
Scale Model ◽  
Conceptual Basis ◽  
Simple Mathematical Model ◽  
Low Aspect Ratio ◽  
Induced Drag ◽  
Tidal Turbine ◽  
Drag And Lift

This paper introduces the patented concept of the Sea Snail, a pin-jointed tubular steel structure carrying an array of symmetrical section hydrofoils, which is used as a means of fixing a tidal turbine, or other devices, to the seabed. The concept is evaluated as a simple mathematical model, tested as a one-eighth-scale model and subsequently developed into a 21 t model fit for sea trials. Pressure differences created by the flow over the upper and lower surfaces of the hydrofoils generate negative lift, or downforce, which is communicated to the supporting structure. The effects of induced drag on low-aspect-ratio hydrofoils are discussed. This paper gives an overview of the evaluative techniques employed in the Sea Snail's concept and design. The need for the device is outlined and its conceptual basis discussed. In particular, the response of a hydrofoil to increasing angles of attack within a steady flow is examined. Field measurements of the drag and lift forces applied to an NACA0013 section hydrofoil is presented in the context of the Sea Snail. The fundamental design criteria are discussed and the Sea Snail's ability to match these criteria is demonstrated.

Design and Verification of a Metal 3D Printing Device Based on Contact Resistance Heating

2019 ◽  
Vol 298 ◽  
pp. 64-68
Author(s):  
Yu Hua Dai ◽  
Xi Wang
Keyword(s):  
3D Printing ◽  
Contact Resistance ◽  
Fused Deposition Modeling ◽  
Numerical Control ◽  
Control Technique ◽  
Resistance Heating ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Fused Deposition ◽  
Metal 3D Printing

As a branch of 3D printing technology, metal 3D printing is an important advanced manufacturing processing method. Metal 3D printing technology has been widely applied in a variety of areas, including the aerospace field, biomedical research and mold manufacturing. This paper proposed a new method for melting metal wires via contact resistance heating. Through the combination of a numerical control technique, a mechanical structure and computer software, a metal 3D printing device was designed based on the principle of fused deposition modeling. The printing nozzle of the device can be heated to over 1400°C in a few minutes. Additionally, we performed experiments with aluminum wire to demonstrate the feasibility of the printing method. The designed consumer-level desktop metal 3D printer cost less than 1500 dollars to fabricate.

scholarly journals Modelling a Snowdrift by Means of Activated Clay Particles

1985 ◽  
Vol 6 ◽  
pp. 48-52 ◽  
Author(s):  
Yutaka Anno
Keyword(s):  
Angle Of Repose ◽  
Scale Model ◽  
Small Scale ◽  
High Angle ◽  
Clay Particles ◽  
Wide Range ◽  
Wet Snow ◽  
Scale Modelling ◽  
Natural Snow ◽  
Small Scale Model

This paper presents a small scale modelling of a snowdrift using activated clay particles.Characteristic properties of activated clay particles, which are different from model snow particles proposed previously by other investigators, are fineness, high angle of repose and wide range of cohesion. Such properties may provide a similitude of a snowdrift and the phenomena caused by wet snow particles in a small scale model.Experimental results presented in this paper show that activated clay particles are the most suitable substitute for natural snow particles in modelling, and indicate also the possibility of using them to model wet snow particles.

Room Acoustic Modelling Techniques: A Comparison of a Scale Model and a Computer Model for a New Opera Theatre

2011 ◽  
Vol 18 (3-4) ◽  
pp. 259-280 ◽  
Author(s):  
Jens Holger Rindel
Keyword(s):  
Satisfactory Agreement ◽  
Computer Simulations ◽  
Computer Model ◽  
Computer Modelling ◽  
Computer Models ◽  
Scale Model ◽  
Acoustic Design ◽  
Acoustic Modelling ◽  
Scale Modelling ◽  
Modelling Techniques

Today most acoustic consultants are using room acoustic computer models as a basis for their acoustic design. However, room acoustic scale modelling is still being used for the design in some major projects, although the costs and the time needed are significantly larger than those related to computer modelling. Both techniques were used by the author in a project for a new opera theatre; first the acoustical design was based on computer simulations using the Odeon software, and next a 1:20 scale model was built and tested. In the paper the results obtained with the two different modelling techniques are compared, and in general a satisfactory agreement has been found. The advantages and drawbacks related to each of the modelling techniques are discussed.

CREATING THREE-DIMENSIONAL MODELS AND DRAWINGS FOR CNC MACHINES IN ARCHITECTURAL SCALE MODELLING

2016 ◽  
Vol 2 (1) ◽  
pp. 175-180
Author(s):  
Соснина ◽  
Olga Sosnina ◽  
Бирюкова ◽  
Alisa Biryukova
Keyword(s):  
Three Dimensional ◽  
Spatial Vision ◽  
Scale Model ◽  
Lighting System ◽  
Cnc Machines ◽  
Industrial Project ◽  
Scale Modelling ◽  
Dimensional Models ◽  
Three Dimensional Models

When working at an architectural or industrial project, it is generally required to make its prototype or scale model, which would accurately replicate the structure designed. Scale modelling permits locating errors and inaccuracies; it enhances spatial vision and promotes architectural thinking. Scale modelling also reveals new features of architectural objects that have already been created. "Nizhny Novgorod Cableway" serves as an example of such objects. The article describes the technology for designing a scale model of the cableway, which demonstrates an updated lighting system on its supports.

A method for obtaining depth estimates from the geometry of Slingram profiles

Geophysics ◽  
1991 ◽  
Vol 56 (10) ◽  
pp. 1543-1552 ◽  
Author(s):  
K. Duckworth ◽  
H. T. Calvert ◽  
J. Juigalli
Keyword(s):  
Linear Relationship ◽  
Free Space ◽  
Phase Inversion ◽  
Spatial Separation ◽  
Depth Estimation ◽  
Scale Model ◽  
Model Studies ◽  
Scale Modelling ◽  
Host Rocks ◽  
Method Show

An approximate method for deriving conductor depth estimates from the geometry of horizontal coplanar coil Slingram type electromagnetic profiles is based on a transformation of the recorded profile to a form which is free of the influence of coil separation. Depth estimates are derived from an empirically determined linear relationship between the spatial separation of maxima on the transformed profile and the depth of the conductor. Field examples and electromagnetic scale modelling indicate that the method works well on both thin and thick conductors with dips ranging from 90 to 60 degrees. Field examples and model results also show that the method works well when a conductive overburden is present, even if the overburden causes phase inversion. Examples of the application of the method show that while knowledge of the conductance of a target will aid in depth estimation, good depth estimates can be made even if the conductance of the target cannot be determined. Comparative scale model studies of conductors located first in free‐space and then in a conductive host suggest that the method will also give good results for targets located in conductive host rocks.

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