scholarly journals Calculation of wave conditions in water area with sharp bottom unevenness

2018 ◽  
Vol 251 ◽  
pp. 04048
Author(s):  
Igor Kantarzhi ◽  
Alexander Gogin
Keyword(s):  
Numerical Simulation ◽  
Numerical Modeling ◽  
Software Package ◽  
Analytical Calculation ◽  
Water Area ◽  
Building Codes ◽  
Hydraulic Structures ◽  
Bottom Relief ◽  
Wave Conditions ◽  
Definition Of

Design of marine hydraulic structures is associated with definition of design wave conditions close by these structures. Safety and economy of hydraulic structures depend exactly on characteristics of wave conditions. In this paper, we consider two methods of obtaining the design wave: analytical calculation using Building Codes and Regulations of Russia and numerical modeling. The MIKE 21 software package was used in this case to perform the numerical simulation. A feature of the considered area is the unevenness of the bottom relief of the water area. The purpose of the article is to show clearly, how much characteristics of the design wave can be overstated when calculating in according to the normative document that does not take into account features of the water area.

scholarly journals Broadband RCS Reduction by a Quaternionic Metasurface

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2787
Author(s):  
Zhao Zhang ◽  
Yazhong Zhang ◽  
Tianlong Wu ◽  
Shaowen Chen ◽  
Wei Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Cross Section ◽  
Phase Difference ◽  
Software Package ◽  
Superposition Principle ◽  
Analytical Calculation ◽  
Scattering Mechanism ◽  
Angular Performance ◽  
Commercial Software Package

A quaternionic metasurface consisting of two pairs of units with destructive phase difference is proposed to extend the bandwidth of radar cross section (RCS) reduction. The two pairs of units are designed to have complementary phase-different bandwidth, which extends the bandwidth of RCS reduction. The overlaps of their bandwidth enhance the RCS reduction, resulting in a metasurface having broadband and strong RCS reduction. This design and the wideband RCS reduction of the quaternionic metasurface were verified by analytical calculation with superposition principle of electric field, numerical simulation with commercial software package CST Microwave Studio and experiment in microwave anechoic chamber. The scattering mechanism and the angular performance of the quaternionic metasurface were also investigated.

Focusing Technique for Holographic Subsurface Radar Based on Image Entropy

2021 ◽  
Vol 36 (4) ◽  
pp. 373-378
Author(s):  
Haewon Jung ◽  
Dal-Jae Yun ◽  
Hoon Kang
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Software Package ◽  
Reconstruction Algorithm ◽  
Simulation Software ◽  
Material Information ◽  
Difference Time ◽  
Actual Depth ◽  
Good Agreement

An image focusing method for holographic subsurface radar (HSR) is proposed herein. HSR is increasingly being utilized to survey objects buried at shallow depths and the acquired signals are converted into an image by a reconstruction algorithm. However, that algorithm requires actual depth and material information or depends on human decisions. In this paper, an entropy-based image focusing technique is proposed and validated by numerical simulation software package based on finite-difference time-domain method and experiment. The resulting images show good agreement with the actual positions and shapes of the targets.

scholarly journals ShakeMaps during the Emilia sequence

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Valentino Lauciani ◽  
Licia Faenza ◽  
Alberto Michelini
Keyword(s):  
Software Package ◽  
Civil Defense ◽  
Peak Ground Velocity ◽  
Accurate Information ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Peak Ground Motion ◽  
Emilia Romagna Region ◽  
Fully Automatic ◽  
Definition Of

<p>ShakeMap is a software package that can be used to generate maps of ground shaking for various peak ground motion (PGM) parameters, including peak ground acceleration (PGA), peak ground velocity, and spectral acceleration response at 0.3 s, 1.0 s and 3.0 s, and instrumentally derived intensities. ShakeMap has been implemented in Italy at the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Geophysics and Volcanology) since 2006 (http://shakemap.rm.ingv.it), with the primary aim being to help the Dipartimento della Protezione Civile (DPC; Civil Protection Department) civil defense agency in the definition of rapid and accurate information on where earthquake damage is located, to correctly direct rescue teams and to organize emergency responses. Based on the ShakeMap software package [Wald et al. 1999, Worden et al. 2010], which was developed by the U.S. Geological Survey (USGS), the INGV is constructing shake maps for Ml ≥3.0, with the adoption of a fully automatic procedure based on manually revised locations and magnitudes [Michelini et al. 2008]. The focus of this study is the description of the progressive generation of these shake maps for the sequence that struck the Emilia-Romagna Region in May 2012. […]</p><br />

scholarly journals Numerical Simulation of Solids Conveying in Grooved Feed Sections of Single Screw Extruders

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 256
Author(s):  
Florian Brüning ◽  
Volker Schöppner
Keyword(s):  
Numerical Simulation ◽  
Analytical Modeling ◽  
Flow Behavior ◽  
Analytical Calculation ◽  
Statistical Design ◽  
Simulation Software ◽  
Special Focus ◽  
Statistical Design Of Experiments ◽  
Complex Flow ◽  
Single Screw Extruders

For plastic processing extruders with grooved feed sections, the design of the feed section by means of analytical calculation models can be useful to reduce experimental costs. However, these models include assumptions and simplifications that can significantly decrease the prediction accuracy of the throughput due to complex flow behavior. In this paper, the accuracy of analytical modeling for calculating the throughput in a grooved barrel extruder is verified based on a statistical design of experiments. A special focus is placed on the assumptions made in the analytics of a backpressure-independent throughput, the assumption of a block flow and the differentiation of the solids conveying into different conveying cases. Simulative throughput tests with numerical simulation software using the discrete element method, as well as experimental throughput tests, serve as a benchmark. Overall, the analytical modeling already shows a very good calculation accuracy. Nevertheless, there are some outliers that lead to larger deviations in the throughput. The model predominantly overestimates the throughputs, whereby the origin of these deviations is often in the conveying angle calculation. Therefore, a regression-based correction factor for calculating the conveying angle is developed and implemented.

scholarly journals The Unresolved Definition of The Pressure-Viscosity Coefficient

2021 ◽  
Author(s):  
Scott Bair
Keyword(s):  
High Temperature ◽  
Equation Of State ◽  
Low Temperature ◽  
Film Thickness ◽  
Pressure Dependence ◽  
Analytical Calculation ◽  
Elastohydrodynamic Lubrication ◽  
Viscosity Coefficient ◽  
Classical Approach ◽  
Definition Of

Abstract In the classical approach to elastohydrodynamic lubrication (EHL) a single parameter, the pressure-viscosity coefficient, quantifies the isothermal pressure dependence of the viscosity for use in prediction of film thickness. Many definitions are in current use. Progress toward a successful definition of this property has been hampered by the refusal of those working in classical EHL to acknowledge the existence of accurate measurements of the piezoviscous effect that have existed for nearly a century. The Hamrock and Dowson pressure-viscosity coefficient at high temperature requires knowledge of the piezoviscous response at pressures which exceed the inlet pressure and may exceed the Hertz pressure. The definition of pressure-viscosity coefficient and the assumed equation of state must limit the use of the classical formulas, including Hamrock and Dowson, to liquids with high Newtonian limit and to low temperature. Given that this problem has existed for at least fifty years without resolution, it is reasonable to conclude that there is no definition of pressure-viscosity coefficient that will quantify the piezoviscous response for an analytical calculation of EHL film thickness at temperatures above ambient.

NUMERICAL SIMULATION OF THE LIGHT AIRCRAFT PROPELLER NOISE UNDER STATIC CONDITION

Akustika ◽  
2021 ◽  
pp. 100-106
Author(s):  
sergey Timushev ◽  
Alexey Yakovlev ◽  
Petr Moshkov
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Modeling ◽  
Vortex Method ◽  
Static Condition ◽  
Semiempirical Model ◽  
Calculation Methods ◽  
Propeller Noise ◽  
Calculation Results ◽  
Static Conditions

The problem of simulation the noise generated during the operation of the propeller is considered. Calculation methods are described and numerical simulation of the noise of a light aircraft propeller by the acoustic-vortex method is performed. The results of numerical modeling of the tonal components of the propeller noise when operating under static conditions are compared with experimental data and calculation results based on a semiempirical model.

Analytical and Calibration Models for Slot Antennas

2019 ◽  
pp. 57-100
Author(s):  
Kok Yeow You
Keyword(s):  
Numerical Simulation ◽  
Analytical Calculation ◽  
Computation Time ◽  
Systematic Errors ◽  
Simulation Software ◽  
Slot Antenna ◽  
Slot Antennas ◽  
Long Period ◽  
Calibration Models ◽  
Calibration Methods

In this chapter, the background, analytical formulations, and calibration routines for slot antennas are briefly reviewed. Performance and operating frequency of the slot antenna are strongly dependent on the dimension and shape of the slot or slotted array on the antenna. Nowadays, most antennas are designed using numerical simulation software for accuracy in analysis. However, analytical formulations still play an important role in the pre-design of the antenna due to the numerical simulation which still requires relatively long period of computation time compared to the analytical calculation. The predicted dimension of the antenna from analytical calculations will only require minor adjustment to optimize its performance in numerical simulation. Hence, the time spent for the antenna design can be shortened. Besides the performance of antenna, the antenna calibration process is crucial as well for releasing systematic errors in the antenna measurements. Some one-port calibration methods are described in detail.

A Semi-Discrete Approach for the Numerical Simulation of Freestanding Blocks

2016 ◽  
pp. 416-439
Author(s):  
Fernando Peña
Keyword(s):  
Differential Equation ◽  
Numerical Simulation ◽  
Numerical Modeling ◽  
Discrete Model ◽  
Mathematical Formulation ◽  
Equation Of Motion ◽  
Rigid Bodies ◽  
The Body ◽  
Discrete Approach ◽  
Rocking Motion

This chapter addresses the numerical modeling of freestanding rigid blocks by means of a semi-discrete approach. The pure rocking motion of single rigid bodies can be easily studied with the differential equation of motion, which can be solved by numerical integration or by linearization. However, when we deal with sliding and jumping motion of rigid bodies, the mathematical formulation becomes quite complex. In order to overcome this complexity, a Semi-Discrete Model (SMD) is proposed for the study of rocking motion of rigid bodies, in which the rigid body is considered as a mass element supported by springs and dashpots, in the spirit of deformable contacts between rigid blocks. The SMD can detect separation and sliding of the body; however, initial base contacts do not change, keeping a relative continuity between the body and its base. Extensive numerical simulations have been carried out in order to validate the proposed approach.

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