scholarly journals Three-Dimensional Mathematical Investigation of Dynamic and Hydrostatic Pressure Distributions on Planing Hulls

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Parviz Ghadimi ◽  
Sasan Tavakoli ◽  
Abbas Dashtimanesh ◽  
Seyed Reza Djeddi
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Hydrostatic Pressure ◽  
Total Pressure ◽  
Three Dimensional ◽  
Hydrodynamic Pressure ◽  
Empirical Equations ◽  
3 Dimensional ◽  
Pressure Distributions ◽  
Mathematical Investigation

A mathematical model is utilized in order to calculate three-dimensional pressure distributions on planing hulls. This type of modeling is able to determine the hydrodynamic and hydrostatic pressures acting on the bottom of these hulls. As a result, the total 3-dimensional pressure exerted on the planing hull as a sum of hydrostatic and hydrodynamic pressures can be evaluated. Empirical equations introduced in previous works have been used as the fundamentals for the present mathematical modeling method. The obtained results are compared against available experimental results and results of empirical equations in order to validate the proposed method. The outcome of the -squared tests conducted on these comparisons shows favorable accuracy of the results. After evaluation of hydrodynamic pressure, the effects of trim and deadrise angles and wetted length on the 3-dimensional pressure distribution are analyzed. Finally, the total pressure on planing hull and the effect of velocity coefficients are studied.

scholarly journals Comparison of Three Measures to Promote National Fitness in China by Mathematical Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Pan Tang ◽  
Daqing Xu ◽  
Qing Dai ◽  
Tingting Huang
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Physical Exercise ◽  
Three Dimensional ◽  
Chinese Government ◽  
Model Parameters ◽  
National Bureau ◽  
Short Period ◽  
Key Parameter

In this paper we established a mathematical model for national fitness in China. Based on a questionnaire and data of the General Administration of Sport of China and the National Bureau of Statistics of China, the dynamics for three classes of people are expressed by a system of three-dimensional ordinary equations. Model parameters are estimated from the data. This study indicated that national fitness put out by the Chinese government is reasonable. By finding the key parameter, the best measure to promote national fitness is put forward. In order to increase the number of people who frequently participate in sport exercise in a short period of time, if only one measure can be chosen, guiding people who never take part in physical exercise will be the best measure.

A Surface Vorticity Theory for Propeller Ducts and Turbofan Engine Cowls in Non-Axisymmetric Incompressible Flow

1978 ◽  
Vol 20 (4) ◽  
pp. 201-219 ◽  
Author(s):  
V. P. Hill
Keyword(s):  
Mathematical Model ◽  
Fourier Series ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Axisymmetric Body ◽  
Fredholm Integral Equations ◽  
Three Dimensional Flow ◽  
Turbofan Engine ◽  
Pressure Distributions ◽  
Theoretical Pressure

Starting from the basic Fredholm integral equations, a surface vorticity theory is developed for the prediction of annular aerofoil performance in three-dimensional flow. A mathematical model is proposed for the general case of the axisymmetric body in non-axisymmetric flow, using a Fourier series to represent circumferential variations in bound vorticity strength. Using the pure incidence case as an example, it is indicated how an economical solution of the flow may be arrived at by use of a digital computer. The theoretical pressure distributions obtained are compared with the results of wind-tunnel tests on an annular aerofoil model.

scholarly journals EFFICIENCY OF WATER FILTERING PROCESS DEPENDING ON THE FILTER LAYER POROSITY AND FLOW - A MATHEMATICAL MODEL

2016 ◽  
Vol 22 (4) ◽  
pp. 54-61
Author(s):  
OANA TIRTOACA IRIMIA ◽  
VALENTIN NEDEFF ◽  
MIRELA PANAINTE-LEHADUS ◽  
CLAUDIA TOMOZEI
Keyword(s):  
Applied Sciences ◽  
Mathematical Modeling ◽  
Mathematical Model ◽  
Experimental Approach ◽  
Three Dimensional ◽  
Filtration Efficiency ◽  
Robust Method ◽  
Intake Flow ◽  
The Mathematical Model ◽  
Filter Layer

Mathematical modeling represents a challenge for any researcher or engineers that working in the field of applied sciences. The experimental approach to the water filtering process allowed achieving and verification a three-dimensional mathematical model, depending on the intake flow of the filter, the porosity of the filter layer and the nature of the filter layer. The mathematical model was developed and verified using the software Table Curve 3D. It was found that the mathematical model proposed offers a viable and robust method for determining the mechanical filtration efficiency of water.

scholarly journals EFFICIENCY OF WATER FILTERING PROCESS DEPENDING ON THE FILTER LAYER POROSITY AND FLOW - A MATHEMATICAL MODEL

2018 ◽  
Vol 22 (4) ◽  
Author(s):  
TIRTOACA (IRIMIA) OANA ◽  
NEDEFF VALENTIN ◽  
PANAINTE-LEHADUS MIRELA ◽  
TOMOZEI CLAUDIA
Keyword(s):  
Applied Sciences ◽  
Mathematical Modeling ◽  
Mathematical Model ◽  
Experimental Approach ◽  
Three Dimensional ◽  
Filtration Efficiency ◽  
Robust Method ◽  
Intake Flow ◽  
The Mathematical Model ◽  
Filter Layer

<p>Mathematical modeling represents a challenge for any researcher or engineers that working in the field of applied sciences. The experimental approach to the water filtering process allowed achieving and verification a three-dimensional mathematical model, depending on the intake flow of the filter, the porosity of the filter layer and the nature of the filter layer. The mathematical model was developed and verified using the software Table Curve 3D. It was found that the mathematical model proposed offers a viable and robust method for determining the mechanical filtration efficiency of water.</p>

scholarly journals A Three-Dimensional Navier-Stokes Calculation Applied to an Axial Compressor Rotor and Stator

1993 ◽  
Author(s):  
Robert P. Dring ◽  
Ricky J. VanSeters ◽  
Robert M. Zacharias
Keyword(s):  
Total Pressure ◽  
Large Scale ◽  
State Of The Art ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Measured Data ◽  
Navier Stokes ◽  
Second Stage ◽  
Compressor Rotor ◽  
Pressure Distributions

The objective of this paper is to apply a three-dimensional Navier-Stokes calculation to the second stage rotor and stator of a large scale compressor and to compare the computed results with measured data. The comparisons include: (1) airfoil and endwall surface streamlines, (2) radial-circumferential distributions of exit total pressure, (3) spanwise distributions of circumferentially averaged inlet and exit flow quantities, and (4) fullspan airfoil pressure distributions. This assessment demonstrates that the computational state-of-the-art has advanced to a point where calculations such as this can be applied with reasonable confidence in both design and analysis situations.

Fabrication and property of auxetic warp-knitted spacer structures with mesh

2017 ◽  
Vol 88 (19) ◽  
pp. 2206-2213 ◽  
Author(s):  
Yuping Chang ◽  
Pibo Ma
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Inclination Angle ◽  
Three Dimensional ◽  
Simple Mathematical Model ◽  
Model Based ◽  
Fabric Density ◽  
Auxetic Structure ◽  
Experimental Sampling

For the purpose of reconstructing a three-dimensional auxetic structure adopting spacer warp-knitting techniques, a simple mathematical model based on the structure of auxetic warp-knitted spacer hexagonal meshes was established and several samples were produced using an E22 RD7/2-12EN warp-knitting machine. It is predicted from synthesizing the results of both mathematical modeling and experimental sampling that auxetic performance of this structure mainly depends on the contraction distortion before stretching in three directions, especially in the y-axis. When it comes to knitting parameters, yarn fineness, machine gauge, fabric density, movement of guide bars, and inclination angle of wales all matter for the auxetic performance, which is also affected by the stiffness of materials and the lodging of spacer yarns. It is also concluded that successive inlaying in the same direction of the spacer guide bar favors contraction distortion in the y-axis, which means auxetic performances can be more easily achieved in this way.

scholarly journals Mathematical Modeling of the Coaxial Quadrotor Dynamics for Its Attitude and Altitude Control

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1232
Author(s):  
Wojciech Giernacki ◽  
Jarosław Gośliński ◽  
Jagoda Goślińska ◽  
Tadeo Espinoza-Fraire ◽  
Jinjun Rao
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Viscous Friction ◽  
Control Techniques ◽  
Aerial Vehicle ◽  
Altitude Control ◽  
Selection Of ◽  
Three Dimensional Space

In this paper, an easily implementable coaxial quadrotor model and its validation on data from a real unmanned aerial vehicle (UAV), are presented. The proposed mathematical model consists of two parts: description of orientation and position of the UAV in the three-dimensional space. It takes into consideration the gyroscopic effect, influence of the Coriolis force, viscous friction and a several drag-like effects (blade flapping, rotor drag, translational drag and profile drag). In contrast to multirotor models available in the literature, this one is characterized by complementarity in relation to the available control techniques. Depending on selection of these techniques, the model can be narrowed (simplified) to meet the needs without the loss of behaviour adequacy to a real UAV.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Design and calibration of an IVEM for general 3-dimensional imaging of non-diffracting materials

1992 ◽  
Vol 50 (2) ◽  
pp. 1040-1041
Author(s):  
Neil Rowlands ◽  
Jeff Price ◽  
Michael Kersker ◽  
Seichi Suzuki ◽  
Steve Young ◽  
...  
Keyword(s):  
3D Imaging ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3 Dimensional ◽  
3D Microstructure ◽  
Image Translation ◽  
Digital Correlation ◽  
On Line ◽  
Mechanical Stage ◽  
Projection Angle

Three-dimensional (3D) microstructure visualization on the electron microscope requires that the sample be tilted to different positions to collect a series of projections. This tilting should be performed rapidly for on-line stereo viewing and precisely for off-line tomographic reconstruction. Usually a projection series is collected using mechanical stage tilt alone. The stereo pairs must be viewed off-line and the 60 to 120 tomographic projections must be aligned with fiduciary markers or digital correlation methods. The delay in viewing stereo pairs and the alignment problems in tomographic reconstruction could be eliminated or improved by tilting the beam if such tilt could be accomplished without image translation.A microscope capable of beam tilt with simultaneous image shift to eliminate tilt-induced translation has been investigated for 3D imaging of thick (1 μm) biologic specimens. By tilting the beam above and through the specimen and bringing it back below the specimen, a brightfield image with a projection angle corresponding to the beam tilt angle can be recorded (Fig. 1a).

Application of the method of mathematical modeling for forecasting channel deformations at the underwater crossing of the main pipeline

2020 ◽  
Vol 10 (6) ◽  
pp. 599-609
Author(s):  
Valery А. Gruzdev ◽  
◽  
Georgy V. Mosolov ◽  
Ekaterina A. Sabayda ◽  
◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Roughness Coefficient ◽  
Computational Domain ◽  
Channel Deformations ◽  
Geological Surveys ◽  
Kuban River ◽  
The Stability ◽  
Protective Structures

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.

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