scholarly journals Forecasting of Surface Currents via Correcting Wind Stress with Assimilation of High-Frequency Radar Data in a Three-Dimensional Model

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Lei Ren ◽  
Stephen Nash ◽  
Michael Hartnett
Keyword(s):  
Data Assimilation ◽  
High Frequency ◽  
Three Dimensional ◽  
Hf Radar ◽  
Surface Velocity ◽  
Shear Stresses ◽  
Surface Currents ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
The Impact

This paper details work in assessing the capability of a hydrodynamic model to forecast surface currents and in applying data assimilation techniques to improve model forecasts. A three-dimensional model Environment Fluid Dynamics Code (EFDC) was forced with tidal boundary data and onshore wind data, and so forth. Surface current data from a high-frequency (HF) radar system in Galway Bay were used for model intercomparisons and as a source for data assimilation. The impact of bottom roughness was also investigated. Having developed a “good” water circulation model the authors sought to improve its forecasting ability through correcting wind shear stress boundary conditions. The differences in surface velocity components between HF radar measurements and model output were calculated and used to correct surface shear stresses. Moreover, data assimilation cycle lengths were examined to extend the improvements of surface current’s patterns during forecasting period, especially for north-south velocity component. The influence of data assimilation in model forecasting was assessed using a Data Assimilation Skill Score (DASS). Positive magnitude of DASS indicated that both velocity components were considerably improved during forecasting period. Additionally, the improvements of RMSE for vector direction over domain were significant compared with the “free run.”

Simulating the Behaviour and Fate of an Oil Spill Using a Coupled Three-Dimensional Hydrodynamic Model

2014 ◽  
Vol 2014 (1) ◽  
pp. 901-918
Author(s):  
James A. Stronach ◽  
Aurelien Hospital
Keyword(s):  
Oil Spill ◽  
Hydrodynamic Model ◽  
Three Dimensional ◽  
Local Network ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Near Surface ◽  
Water Properties ◽  
Response Planning ◽  
The Impact

ABSTRACT Oil behavior and fate have been simulated extensively by several spill models. These simulations can be greatly enhanced by the use of a coupled three-dimensional model of currents and water properties to determine oil transport and weathering, both on the water surface and in the water column. Several physical and chemical processes such as vertical dispersion in response to wave action, resurfacing when waves die down, sinking through loss of volatiles and dissolution are essential in assessing the impact of an oil spill on the environment. Dissolution is especially important, considering the known toxicity of several of the constituents of liquid hydrocarbons. For this study, a three-dimensional hydrodynamic model of coastal British Columbia was coupled to an oil trajectory and weathering model in order to simulate the complete fate and behaviour of surface, shoreline-retained, dissolved, sunken and dispersed oil. Utilization of a three-dimensional model is the key to adequately modelling the transport of a spill in an estuarine region such as in the Strait of Georgia, B.C., where the distribution of currents and water properties is strongly affected by estuarine processes: the Fraser River enters at the surface and oceanic waters from the Pacific enter as a deep inflow. Three-dimensional currents and water properties were provided by the hydrodynamic model, H3D, a semi-implicit model using a staggered Arakawa grid and variable number of layers in the vertical direction to resolve near-surface processes. Waves were simulated using the wave model SWAN. Winds were obtained from the local network of coastal light stations and wind buoys. Stochastic modelling was conducted first, using only surface currents, to determine probabilistic maps of the oil trajectory on water and statistical results were extracted, such as the amount of shoreline oiled and the amount of oil evaporated, both for the ensemble of simulations constituting the stochastic simulation, as well as for any particular individual simulation. Deterministic scenarios were then selected and the fate of the oil, such as the dissolved and sunken fractions, was tracked over a 14 day period on the three-dimensional grid. This method has been used for environmental impact assessment and spill response planning.

Research of the Installation Angle of New Rotor Impact Plate Based on EDEM

2011 ◽  
Vol 80-81 ◽  
pp. 1133-1137
Author(s):  
De Rong Duan ◽  
Fang Zhao ◽  
Song Wang ◽  
Xian Xin Chen
Keyword(s):  
Dynamic Simulation ◽  
Impact Force ◽  
Three Dimensional ◽  
Substantial Effect ◽  
Maximum Speed ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Installation Angle ◽  
Impact Plate ◽  
The Impact

The three-dimensional model of new rotor was imported into EDEM for dynamic simulation, the maximum speed and force were analysied in the EDEM,indicating that the material along the deterministic trajectory collide with the impact plate for second acceleration after the first acceleration in new rotor, the velocity after second acceleration was 2.3 times than the first acceleration.The impact force and angle did not substantial effect on the second acceleration by comprehensive comparing,the 69m/s speed and less impact force were generated in the new rotor with 2° impact plate installation angle.

scholarly journals Thermal functioning of a tropical reservoir assessed through three-dimensional modelling and high-frequency monitoring

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Denis Furstenau Plec ◽  
Talita Fernanda das Graças Silva ◽  
Brigitte Vinçon-Leite ◽  
Nilo Nascimento
Keyword(s):  
Water Temperature ◽  
High Frequency ◽  
Three Dimensional ◽  
Frequency Measurement ◽  
Three Dimensional Model ◽  
Anthropogenic Pressures ◽  
Tropical Reservoir ◽  
River Temperature ◽  
Lake Morphology ◽  
The Impact

ABSTRACT Urban lakes and reservoirs provide important ecosystem services. However, their water quality is being affected by anthropogenic pressures. The thermal regime is a strong driver of the vertical transport of nutrients, phytoplankton and oxygen. Thermal stratification can modify biogeochemical processes. In this paper, a three-dimensional hydrodynamic model was implemented and validated with high-frequency measurement of water temperature. The simulation results were in agreement with the measurements. For all simulation period, the model performance was evaluated based on hourly values, presenting a maximum RMSE of 0.65 ºC and Relative Error of 2.08%. The results show that high-frequency measurement associated with a three-dimensional model could help to understand and identify the reasons for the changes in the thermal condition of a shallow urban lake. The impact of the stream inflow on the temperature was highlighted, showing that during higher discharge events, when the river temperature is colder than the lake water, it flows into the lake deeper layers. The inflow water sank to the deeper layers where the lake morphology changes. The model showed an impact along the entire lake, showing the importance of monitoring the inflow water temperature. This modelling tool could be further used to study specific patterns of reservoir hydrodynamics.

The Dynamic Simulation Study of WN Gear Pair after Coupling Tribology

2014 ◽  
Vol 577 ◽  
pp. 214-217
Author(s):  
Yu Guang Li ◽  
Guo Qing Zhang
Keyword(s):  
Dynamic Simulation ◽  
Three Dimensional ◽  
Dynamic Contact ◽  
Axial Vibration ◽  
Dimensional Model ◽  
Analysis Model ◽  
Ansys Software ◽  
Three Dimensional Model ◽  
Dimensional Simulation ◽  
The Impact

Based on WN gear characteristics and considering system error, a multi-degree-freedom (Tangential-Radial-Axial) dynamics analysis model after coupling friction was established. In this article, we established the three-dimensional solid model by using PROE and then imported WN gear’ three-dimensional model into Ansys software through the data interface of Ansys software and PROE software and conducted a three-dimensional simulation anasys of the impact of dynamic contact. By applying load, the stress analysis of WN gear was conducted and the WN gear’s the effective stress clouds was gotten. Meanwhile, basing on ANSYS / LS-DYNA, it established the rigid-flexible body of gear dynamic contact model and analyzed the dynamic simulation anasys of WN gear. The results demonstrated that the tangential and axial vibration of double arc gear was significantly greater than the radial vibration.

A Three-Dimensional Model of Droplet Impinging, Solidification and Suspension on the Substrate

2011 ◽  
Vol 346 ◽  
pp. 222-227
Author(s):  
Sheng Zhu ◽  
Feng Liang Yin ◽  
Jian Liu ◽  
Yuan Yuan Liang
Keyword(s):  
Surface Tension ◽  
Manufacturing Process ◽  
Three Dimensional ◽  
Metal Droplet ◽  
The Body ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
High Impact Velocity ◽  
The Impact ◽  
First Time

A three-dimensional model was built to study a molten metal droplet impact on an edge of the substrate in droplet deposition manufacturing process for the first time. The whole calculation domain, including the substrate, was described using same fluid conservation equations, which is to say that the remolding and solidification of substrate was considered also. Droplet free surface was tracked by volume-of-fluid (VOF) algorithm. The effect of surface tension on the droplet was taken into consideration by means of considering surface tension to be a component of the body force. The simulated results show that the droplet in liquid phase can keep suspending on the substrate at a role of surface tension. A too high impact velocity would make parts of droplet splash away the substrate which is not allowed in manufacturing process. The offset between edge of droplet and side edge of substrate influences dramatically the impact of the droplet.

scholarly journals Influence of the occlusal contacts in formation of Abfraction Lesions in the upper premolar

2017 ◽  
Vol 20 (4) ◽  
pp. 115 ◽  
Author(s):  
Victória Luswarghi Souza Costa ◽  
João Paulo Mendes Tribst ◽  
Alexandre Luiz Souto Borges
Keyword(s):  
Three Dimensional ◽  
Cervical Region ◽  
Shear Stresses ◽  
Dimensional Model ◽  
Analysis Software ◽  
Three Dimensional Model ◽  
Finite Elements Analysis ◽  
Element Analysis ◽  
Occlusal Contact ◽  
Biomechanical Behavior

<p><strong>Objective:</strong> The aim of this study was to observe the influence of different occlusal contacts in a superior pre-molar structure using Finite Element Analysis. <strong>Material and Methods:</strong> A three-dimensional model of a superior pre-molar was designed to simulate three occlusion situations, namely central occlusion and two types of lateral occlusion contacts. The model presents enamel, dentin, a periodontal ligament and a fixation cylinder separately. All materials were considered isotropic, linear and homogeneous, and the contacts of each structure were perfectly bonded. On analysis software, a load was applied to an occlusal surface at 40° to the long axis on lateral contacts, and directed to the long axis on central occlusion contact. <strong>Results:</strong> The results were obtained in stress maps and the maximum values were then plotted in table for quantitative comparison, with the enamel concentrating more stress than dentin and the occlusal contact presenting the worst biomechanical behavior. <strong>Conclusion: </strong>Within the limitations of this study, it is possible conclude that: eccentric contacts have higher potential to develop abfraction lesions on the cervical region of teeth, thus increasing the magnitude of tensile and shear stresses.</p><p><strong>Keywords</strong></p><p>Finite Elements Analysis, Abfraction; Stress distribution; Occlusion, Premolar.</p>

scholarly journals Observing and modeling currents on the continental slope: assimilation of high frequency radar currents and hydrography profiles

2014 ◽  
Vol 11 (3) ◽  
pp. 1357-1390
Author(s):  
A. K. Sperrevik ◽  
K. H. Christensen ◽  
J. Röhrs
Keyword(s):  
Data Assimilation ◽  
High Frequency ◽  
Ocean Modeling ◽  
Hf Radar ◽  
Regional Ocean Modeling System ◽  
Background Error ◽  
Realistic Case ◽  
Analysis Scheme ◽  
Surface Drifters ◽  
The Impact

Abstract. Assimilation of High Frequency (HF) radar current observations and CTD hydrography is performed with the 4D-Var analysis scheme implemented in the Regional Ocean Modeling System (ROMS). We consider both an idealized case, with a baroclinic slope current in a periodic channel, and a realistic case for the coast of Vesterålen in Northern Norway. In the realistic case the results of the data assimilation are compared with independent data from acoustic profilers and surface drifters. Best results are obtained when background error correlation scales are small (10 km or less) and when the data assimilation window is short, i.e. about one day. Furthermore, we find that the impact of assimilating HF radar currents is generally larger than the impact of CTD hydrography, which implies that the amount of hydrographic data is insufficient to constrain the solution. Combining the HF radar currents with a few hydrographic profiles gives significantly better results, which demonstrates the importance of complementing surface observations with observations of the vertical structure of the ocean.

Numerical Simulation on Drawing Deep of Cylindrical Pieces Based on Dynaform

2014 ◽  
Vol 684 ◽  
pp. 252-258 ◽  
Author(s):  
Jun Hong Wang ◽  
Xu Dong Bao ◽  
Hai Mei Feng ◽  
Chang Du
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Forming Process ◽  
Minimum Thickness ◽  
Optimum Parameters ◽  
Design And Manufacture ◽  
The Impact

Abstract: The design and manufacture of mold often rely on the experience of the designers, which led to the fact that the mold needs to be repeatedly debugged and corrected. Numerical simulation technology enables the simulation of the forming process of sheet metal and prediction of defects in design, thus to improve labor efficiency, save time and reduce costs. In this paper, the software Dynaform is used as a platform and a three-dimensional model is built to numerical simulate and analyze the drawing deep of a typical thin-walled cylindrical piece.Orthogonal experimentis adopted to analyze the impact of BHF, punching speed and punch-die gap on forming quality of the drawing pieces. With minimum thickness and wrinkling as indicators, the impact of various factors is analyzed and a set of optimum parameters is found out that is, BHF is 20kN, punching speed is 2000mm / s and punch-die gap is 0.9mm.

The Impact of Social Influence Pressures, Commitment, and Personality on Judgments by Auditors: Evidence from Japan

2017 ◽  
Vol 16 (3) ◽  
pp. 17-34 ◽  
Author(s):  
Noriyuki Tsunogaya ◽  
Satoshi Sugahara ◽  
Parmod Chand
Keyword(s):  
Organizational Commitment ◽  
Social Influence ◽  
Significant Influence ◽  
Three Dimensional ◽  
Personal Attributes ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Audit Firms ◽  
Conformity Pressure ◽  
The Impact

ABSTRACT We examine whether obedience and conformity pressures generated by superiors (partners) and colleagues within audit firms cause dysfunctional audit behavior in Japan. We also investigate whether high levels of professional and organizational commitment and the personal attributes of auditors mitigate these pressures. The results indicate that obedience pressure can impair the judgments of auditors, whereas conformity pressure does not have a significant influence. The application of a three-dimensional model of commitment and a five-dimensional scale of individual personalities reveals that dysfunctional audit behavior can be mitigated by enhancing affective and normative commitment, and by addressing highly masculine characteristics in individual auditors.

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