Modeling quasi‐one‐dimensional sound propagation in ducts having two propagation media using a cross‐sectional averaging theory

2006 ◽  
Vol 120 (5) ◽  
pp. 3284-3284
Author(s):  
Donald Bliss ◽  
Lisa Burton
Keyword(s):  
Sound Propagation ◽  
Averaging Theory ◽  
Cross Sectional ◽  
One Dimensional ◽  
Propagation Media

The Exact One-Dimensional Theory for End-Loaded Fully Anisotropic Beams of Narrow Rectangular Cross Section

2001 ◽  
Vol 68 (6) ◽  
pp. 865-868 ◽  
Author(s):  
P. Ladeve`ze ◽  
J. G. Simmonds
Keyword(s):  
Cross Section ◽  
Plane Stress ◽  
Rectangular Cross Section ◽  
Dimensional Theory ◽  
Explicit Formulas ◽  
Cross Sectional ◽  
Rectangular Shape ◽  
One Dimensional ◽  
Anisotropic Elastic ◽  
Derivatives Of

The exact theory of linearly elastic beams developed by Ladeve`ze and Ladeve`ze and Simmonds is illustrated using the equations of plane stress for a fully anisotropic elastic body of rectangular shape. Explicit formulas are given for the cross-sectional material operators that appear in the special Saint-Venant solutions of Ladeve`ze and Simmonds and in the overall beamlike stress-strain relations between forces and a moment (the generalized stress) and derivatives of certain one-dimensional displacements and a rotation (the generalized displacement). A new definition is proposed for built-in boundary conditions in which the generalized displacement vanishes rather than pointwise displacements or geometric averages.

Long waves in a straight channel with non-uniform cross-section

2015 ◽  
Vol 770 ◽  
pp. 156-188 ◽  
Author(s):  
Patricio Winckler ◽  
Philip L.-F. Liu
Keyword(s):  
Boundary Layer ◽  
Wave Propagation ◽  
Cross Section ◽  
Three Dimensional ◽  
Channel Cross Section ◽  
Cross Sectional ◽  
New Model ◽  
One Dimensional ◽  
Uniform Channel ◽  
The Cross

A cross-sectionally averaged one-dimensional long-wave model is developed. Three-dimensional equations of motion for inviscid and incompressible fluid are first integrated over a channel cross-section. To express the resulting one-dimensional equations in terms of the cross-sectional-averaged longitudinal velocity and spanwise-averaged free-surface elevation, the characteristic depth and width of the channel cross-section are assumed to be smaller than the typical wavelength, resulting in Boussinesq-type equations. Viscous effects are also considered. The new model is, therefore, adequate for describing weakly nonlinear and weakly dispersive wave propagation along a non-uniform channel with arbitrary cross-section. More specifically, the new model has the following new properties: (i) the arbitrary channel cross-section can be asymmetric with respect to the direction of wave propagation, (ii) the channel cross-section can change appreciably within a wavelength, (iii) the effects of viscosity inside the bottom boundary layer can be considered, and (iv) the three-dimensional flow features can be recovered from the perturbation solutions. Analytical and numerical examples for uniform channels, channels where the cross-sectional geometry changes slowly and channels where the depth and width variation is appreciable within the wavelength scale are discussed to illustrate the validity and capability of the present model. With the consideration of viscous boundary layer effects, the present theory agrees reasonably well with experimental results presented by Chang et al. (J. Fluid Mech., vol. 95, 1979, pp. 401–414) for converging/diverging channels and those of Liu et al. (Coast. Engng, vol. 53, 2006, pp. 181–190) for a uniform channel with a sloping beach. The numerical results for a solitary wave propagating in a channel where the width variation is appreciable within a wavelength are discussed.

scholarly journals How to Evaluate Digital Leadership: A Cross-sectional Study

2021 ◽  
Author(s):  
Kevin Claassen ◽  
Dominique Rodil Dos Anjos ◽  
Jan Kettschau ◽  
Horst Christoph Broding
Keyword(s):  
Construct Validity ◽  
Online Survey ◽  
Leadership Skills ◽  
Principal Component ◽  
Cross Sectional Study ◽  
Working Environment ◽  
Cross Sectional ◽  
One Dimensional ◽  
Leadership Competence ◽  
Transformation Processes

Abstract Background: With the increasing digitalization of the working environment, the demands on managers are changing fundamentally to the point of an emerging field of research in digital leadership. Municipal administrations are particularly affected by the digital transformation processes. Therefore, a score to measure the construct of digital leadership competence in the context of virtual-based workstation was developed and tested.Methods: Based of an online survey with n = 546 employees at virtual-based workstations in municipal administrations in 2020, the instrument is tested regarding selectivity (coefficients), dimensionality (principal component analysis), homogeneity (inter-product-moment correlations), reliability (Cronbach's α) and construct validity (correlation with general leadership skills).Results: The instrument can be considered selective, one-dimensional, homogeneous, reliable and constructively valid in the sense of the formulated hypotheses. By integrating the employees‘ perspective, the instrument aims to be one of the first of its kind to initiate a scientific further discourse. Among other things, the categorization of the co-determination component as either traditional or digital leadership can be discussed.Conclusions: The developed instrument for measuring digital leadership performs well concerning the aspects of discriminatory power, one-dimensionality, homogeneity, reliability as well as construct validity. It aims to induce further research and a scientific discourse on the topic of health-oriented leadership within the world of work 4.0.

Statistical Thermodynamics and Surface Phase Transitions of Interacting Particles Adsorbed on One-Dimensional Channels Arranged in a Triangular Cross-Sectional Structure

2009 ◽  
Vol 150 ◽  
pp. 73-100 ◽  
Author(s):  
P.M. Pasinetti ◽  
F. Romá ◽  
J.L. Riccardo ◽  
A.J. Ramirez-Pastor
Keyword(s):  
Monte Carlo ◽  
Interaction Energy ◽  
Lattice Gas ◽  
Nearest Neighbor ◽  
Single Channel ◽  
Scaling Analysis ◽  
Surface Phase ◽  
Cross Sectional ◽  
One Dimensional ◽  
Sectional Structure

Monte Carlo simulations and finite-size scaling analysis have been carried out to study the critical behavior in a submonolayer lattice-gas, which mimics a nanoporous environment. In this model, one-dimensional chains of atoms were arranged in a triangular cross-sectional structure. Two kinds of lateral interaction energies have been considered: (1) wL, interaction energy between nearest-neighbor particles adsorbed along a single channel and (2) wT, interaction energy between particles adsorbed across nearest-neighbor channels. We focus on the case of repulsive transverse interactions (wT > 0), where a rich variety of structural orderings are observed in the adlayer, depending on the value of the parameters kBT/wT (kB being the Boltzmann constant) and wL /wT. For wL /wT = 0, successive planes are uncorrelated, the system is equivalent to the triangular lattice, and the well-known [ ] ordered phase is found at low temperatures and a coverage, , of 1/3 [2/3]. In the more general case (wL /wT  0), the competition between interactions along a single channel and the transverse coupling between sites in neighboring channels leads to a three-dimensional adsorbed layer. Consequently, the and structures “propagate” along the channels and new ordered phases appear in the adlayer. The influence of each ordered phase on adsorption isotherms, differential heat of adsorption and configurational entropy of the adlayer has been analyzed and discussed in the context of the lattice-gas theory. Finally, the Monte Carlo technique was combined with the recently reported free energy minimization criterion approach (FEMCA) [F. Romá et al.: Phys. Rev. B Vol. 68 (2003), art. no. 205407] to predict the critical temperatures of the surface-phase transformations occurring in the adsorbate. The excellent qualitative agreement between simulated data and FEMCA results allows us to interpret the physical meaning of the mechanisms underlying the observed transitions.

Verification of a Finite Element Method for Solving One-Dimensional Equations of Blood Flow Incorporating a Viscoelastic Wall Model

2009 ◽  
Author(s):  
Rashmi Raghu ◽  
Charles A. Taylor
Keyword(s):  
Blood Flow ◽  
Surgical Planning ◽  
Computational Cost ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Cross Sectional ◽  
One Dimensional ◽  
The One ◽  
Modeling Flow ◽  
Three Dimensional Simulations

The one-dimensional (1-D) equations of blood flow consist of the conservation of mass equation, balance of momentum equation and a wall constitutive equation with arterial flow rate, cross-sectional area and pressure as the variables. 1-D models of blood flow enable the solution of large networks of blood vessels including wall deformability. Their level of detail is appropriate for applications such as modeling flow and pressure waves in surgical planning and their computational cost is low compared to three-dimensional simulations.

Modelling of Rotating Twisted Blades as 1D Continuum

2016 ◽  
Vol 821 ◽  
pp. 183-190
Author(s):  
Jan Brůha ◽  
Drahomír Rychecký
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Beam Theory ◽  
Parameter Tuning ◽  
Finite Element Models ◽  
Cross Sectional ◽  
One Dimensional ◽  
Rayleigh Beam ◽  
Twisted Blade ◽  
Sectional Parameters

Presented paper deals with modelling of a twisted blade with rhombic shroud as one-dimensional continuum by means of Rayleigh beam finite elements with varying cross-sectional parameters along the finite elements. The blade is clamped into a rotating rigid disk and the shroud is considered to be a rigid body. Since the finite element models based on the Rayleigh beam theory tend to slightly overestimate natural frequencies and underestimate deflections in comparison with finite element models including shear deformation effects, parameter tuning of the blade is performed.

LATTICE GAS WAVE PROPAGATION MODELS INCLUDING DISSIPATION

1995 ◽  
Vol 03 (01) ◽  
pp. 69-93 ◽  
Author(s):  
YASUSHI SUDO ◽  
VICTOR W. SPARROW
Keyword(s):  
Wave Propagation ◽  
Random Walk ◽  
Diffusion Equation ◽  
Lattice Gas ◽  
Sound Propagation ◽  
Two Dimensional ◽  
Propagation Models ◽  
One Dimensional ◽  
Lattice Gas Models ◽  
Wave Models

New lattice gas models for one-dimensional (1D) and two-dimensional (2D) sound propagation have been recently proposed by the authors. These models were dissipationless and deterministic. In this paper, it will be shown how dissipation effects can be included into these lattice gas wave models. To simulate these dissipation effects, the lattice gas particles are assumed to take a random walk. The resulting models combine the authors' lattice gas wave models with published lattice gas models for the diffusion equation. The formulations are stable and consistent.

scholarly journals GHQ-12 in adolescents: contributions to the controversial factorial validity

2020 ◽  
Vol 36 (2) ◽  
pp. 247-253
Author(s):  
Eduardo J. Pedrero Pérez ◽  
Carlos Mora-Rodríguez ◽  
Rosana Rodríguez Gómez ◽  
María Teresa Benítez-Robredo ◽  
Ana Ordóñez-Franco ◽  
...  
Keyword(s):  
Mental Health Problems ◽  
Adult Population ◽  
Three Dimensions ◽  
Female Adolescents ◽  
Factorial Structure ◽  
Scoring Method ◽  
Cross Sectional ◽  
One Dimensional ◽  
Development Level ◽  
The City

Objective: The GHQ-12 is one of the most widely used questionnaires in the adult population, but there are not as many studies exploring its applicability in adolescents. The main problem is the diversity of results on its factorial structure, as different studies have shown one, two or three dimensions. The purpose of this study was to explore the GHQ-12 factorial structure for adolescents. Method: An observational multicenter cross-sectional descriptive study was designed for schools in the city of Madrid. A random sample of n=2,171, 14-16-year-olds was stratified by the school’s development level and funding (public, private or mixed). Unrestricted factor analysis was applied based on the polychoric or tetrachoric correlations matrix (depending on the test scoring method). Results: The optimized parallel analysis provided an unequivocal one-factor structure, confirmed by unidimensionality assessment. Around 30% of male and 42% of female adolescents were found to be at risk of developing mental health problems. Conclusions: The GHQ-12 is a one-dimensional test for screening psychological distress, with excellent psychometric properties for its application in an adolescent population. The use of adequate statistical methods can overcome old controversies and promote proper application and interpretation of the results provided by the test.

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