scholarly journals An experimental investigation to model wheezing in lungs

2021 ◽  
Vol 8 (2) ◽  
Author(s):  
A. L. Gregory ◽  
A. Agarwal ◽  
J. Lasenby
Keyword(s):  
Experimental Investigation ◽  
Lung Diseases ◽  
Necessary Conditions ◽  
Quantitative Model ◽  
Sectional Area ◽  
Predictive Tool ◽  
Cross Sectional ◽  
Physical Mechanisms ◽  
Elastic Tubes ◽  
Deformed State

A quarter of the world's population experience wheezing. These sounds have been used for diagnosis since the time of the Ebers Papyrus ( ca 1500 BC). We know that wheezing is a result of the oscillations of the airways that make up the lung. However, the physical mechanisms for the onset of wheezing remain poorly understood, and we do not have a quantitative model to predict when wheezing occurs. We address these issues in this paper. We model the airways of the lungs by a modified Starling resistor in which airflow is driven through thin, stretched elastic tubes. By completing systematic experiments, we find a generalized ‘tube law’ that describes how the cross-sectional area of the tubes change in response to the transmural pressure difference across them. We find the necessary conditions for the onset of oscillations that represent wheezing and propose a flutter-like instability model for it about a heavily deformed state of the tube. Our findings allow for a predictive tool for wheezing in lungs, which could lead to better diagnosis and treatment of lung diseases.

scholarly journals Geometry of the Vocal Tract and Properties of Phonation near Threshold: Calculations and Measurements

2019 ◽  
Vol 9 (13) ◽  
pp. 2755 ◽  
Author(s):  
Lewis Fulcher ◽  
Alexander Lodermeyer ◽  
George Kähler ◽  
Stefan Becker ◽  
Stefan Kniesburges
Keyword(s):  
Vocal Tract ◽  
Wave Model ◽  
Vocal Folds ◽  
Cross Sectional Area ◽  
Inertial Effects ◽  
Sectional Area ◽  
Cross Sectional ◽  
Physical Mechanisms ◽  
Lumped Element ◽  
Geometrical Boundary

In voice research, analytically-based models are efficient tools to investigate the basic physical mechanisms of phonation. Calculations based on lumped element models describe the effects of the air in the vocal tract upon threshold pressure (Pth) by its inertance. The latter depends on the geometrical boundary conditions prescribed by the vocal tract length (directly) and its cross-sectional area (inversely). Using Titze’s surface wave model (SWM) to account for the properties of the vocal folds, the influence of the vocal tract inertia is examined by two sets of calculations in combination with experiments that apply silicone-based vocal folds. In the first set, a vocal tract is constructed whose cross-sectional area is adjustable from 2.7 cm2 to 11.7 cm2. In the second set, the length of the vocal tract is varied from 4.0 cm to 59.0 cm. For both sets, the pressure and frequency data are collected and compared with calculations based on the SWM. In most cases, the measurements support the calculations; hence, the model is suited to describe and predict basic mechanisms of phonation and the inertial effects caused by a vocal tract.

scholarly journals Experimental Investigation on Behavior of Rectangular Concrete-Filled Tubular Columns Considering Diaphragms

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4412
Author(s):  
Sang-Lyul Cha ◽  
Jung-Soo Lee ◽  
Chan-Kyu Park ◽  
Jin-Keun Kim ◽  
Seung-Hee Kwon
Keyword(s):  
Experimental Investigation ◽  
High Strength ◽  
Failure Behavior ◽  
High Ductility ◽  
Inelastic Behavior ◽  
Structural Members ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tubular Columns ◽  
Energy Dissipation Capacity

Concrete-filled tubular (CFT) columns have been widely used as structural members because CFT columns synergize the advantages of steel and concrete resulting in high strength, high ductility, and large energy dissipation capacity. Numerous studies have been performed to understand the behavior of CFT columns. However, the behavior of CFT columns remains uncertain due to their inelastic behavior and uncertain confinement effects, especially when failure occurs. In addition, diaphragms, which are generally installed, make it more complicated to understand the behavior of CFT columns. The purpose of this study is to investigate the effects of the diaphragms on the failure behavior of the CFT columns. To this end, eighteen rectangular CFT columns were tested with five different loading cases. The experimental results suggest that the size of the diaphragm has significant effects on the compressive strength and toughness of the CFT columns. In order to facilitate the proper composite actions of steel and concrete, the size of a diaphragm has to be at least three-quarters of the cross-sectional area.

An Experimental Investigation of the Capillary Performance of Triangular Versus Sinusoidal Channels

1997 ◽  
Vol 119 (4) ◽  
pp. 851-853 ◽  
Author(s):  
G. R. Stroes ◽  
I. Catton
Keyword(s):  
Heat Flux ◽  
Experimental Investigation ◽  
Heat Input ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Average Heat ◽  
Wetted Area

This paper discusses an experimental investigation of the performance of capillary channels with sinusoidal versus triangular geometry. Results indicate that for equivalent cross-sectional area, angle of inclination, and heat input from below, a triangular groove geometry sustains a larger wetted area while a sinusoidal groove geometry supports a greater average heat flux.

Experimental Investigation on Aerodynamic Characteristics of a Variable Area Nozzleless Volute

1985 ◽  
Author(s):  
Feng Zhenping ◽  
Shen Zuda ◽  
Xiang Yimin
Keyword(s):  
Experimental Investigation ◽  
Aerodynamic Characteristics ◽  
Sectional Area ◽  
Cross Sectional ◽  
Flow Angle ◽  
Rate Range ◽  
Flow Parameters ◽  
Outlet Flow ◽  
Flow Rate Range ◽  
Aerodynamic Parameters

The aerodynamic characteristics of a variable area nozzleless volute (VAV) for small radial inflow turbines are studied with the aid of cold air tests in which flow parameters inside the volute channel and at the outlet of the nozzleless ring are measured for cases of various cross-sectional areas. The experimental investigation shows that the desired aerodynamic parameters, especially the outlet flow angle α1 as well as the mass flow rate range can be obtained by varying the croes-sectional area of the VAV. A reasonable approximate method for calculating the average outlet flow angle α1 is presented in which the variation of the circulation in the flow is taken into account.

Pelvic Canal Narrowing Caused by Triple Pelvic Osteotomy in the Dog

1994 ◽  
Vol 07 (03) ◽  
pp. 110-113 ◽  
Author(s):  
D. L. Holmberg ◽  
M. B. Hurtig ◽  
H. R. Sukhiani
Keyword(s):  
Postoperative Complications ◽  
Pelvic Osteotomy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Canal Width ◽  
Operative Complications ◽  
Post Operative Complications

SummaryDuring a triple pelvic osteotomy, rotation of the free acetabular segment causes the pubic remnant on the acetabulum to rotate into the pelvic canal. The resulting narrowing may cause complications by impingement on the organs within the pelvic canal. Triple pelvic osteotomies were performed on ten cadaver pelves with pubic remnants equal to 0, 25, and 50% of the hemi-pubic length and angles of acetabular rotation of 20, 30, and 40 degrees. All combinations of pubic remnant lengths and angles of acetabular rotation caused a significant reduction in pelvic canal-width and cross-sectional area, when compared to the inact pelvis. Zero, 25, and 50% pubic remnants result in 15, 35, and 50% reductions in pelvic canal width respectively. Overrotation of the acetabulum should be avoided and the pubic remnant on the acetabular segment should be minimized to reduce postoperative complications due to pelvic canal narrowing.When performing triple pelvic osteotomies, the length of the pubic remnant on the acetabular segment and the angle of acetabular rotation both significantly narrow the pelvic canal. To reduce post-operative complications, due to narrowing of the pelvic canal, overrotation of the acetabulum should be avoided and the length of the pubic remnant should be minimized.

DETERMINATION OF THE FUNCTION OF THE ROD’S CROSS-SECTIONAL AREA USING VIBRATION EIGENFREQUENCIES

2020 ◽  
Vol 0 (4) ◽  
pp. 19-24
Author(s):  
I.M. UTYASHEV ◽  
◽  
A.A. AITBAEVA ◽  
A.A. YULMUKHAMETOV ◽  
◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Variable Cross ◽  
Sectional Area ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Method Error ◽  
Various Boundary Conditions ◽  
Elastic Fixation ◽  
Crosssectional Area

The paper presents solutions to the direct and inverse problems on longitudinal vibrations of a rod with a variable cross-sectional area. The law of variation of the cross-sectional area is modeled as an exponential function of a polynomial of degree n . The method for reconstructing this function is based on representing the fundamental system of solutions of the direct problem in the form of a Maclaurin series in the variables x and λ. Examples of solutions for various section functions and various boundary conditions are given. It is shown that to recover n unknown coefficients of a polynomial, n eigenvalues are required, and the solution is dual. An unambiguous solution was obtained only for the case of elastic fixation at one of the rod’s ends. The numerical estimation of the method error was made using input data noise. It is shown that the error in finding the variable crosssectional area is less than 1% with the error in the eigenvalues of longitudinal vibrations not exceeding 0.0001.

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