Validation of Respiratory Resistance Measurements

2011 ◽  
Author(s):  
James Pan ◽  
Andrew Saltos ◽  
Dan Smith ◽  
Arthur Johnson ◽  
Jafar Vossoughi
Keyword(s):  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Impulse Oscillometry ◽  
Respiratory Resistance ◽  
Calibration System ◽  
Limited Data ◽  
Normal Range ◽  
Flow Generator ◽  
Sinusoidal Flow ◽  
Airflow Perturbation Device

The airflow perturbation device (APD) has been developed as a portable, easy to use, and rapid-response instrument for noninvasively measuring respiratory resistance in humans. However, the APD has limited data validating it against established techniques; moreover, a method does not exist to standardize resistance measurement outputs between APD units. This study proposes a system that simulates the normal range of human breathing to validate the APD with the clinically accepted impulse oscillometry technique. Two respiratory resistance ranges were tested. The validation system consisted of a sinusoidal flow generator with ten standardized resistance configurations that were shown to represent a total range of resistances from 0.7000–9.4475 cmH2O·L−1·s−1. Impulse oscillometry (IOS) measurements and APD measurements of the calibration system were recorded and compared at a constant volumetric flow rate of 0.150 L·s−1. Both IOS and the APD consistently failed to estimate nominal resistance accurately. However, a strong second-order relationship was observed between APD measurements and IOS measurements (R2 = 0.997). Because of their comparability to IOS measurements, APD measurements are shown to be valid representations of respiratory resistance in a standard pneumatic model.

scholarly journals Comparison of Respiratory Resistance Measurements Made with an Airflow Perturbation Device with Those from Impulse Oscillometry

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
J. Pan ◽  
A. Saltos ◽  
D. Smith ◽  
A. Johnson ◽  
J. Vossoughi
Keyword(s):  
Mechanical System ◽  
Impulse Oscillometry ◽  
Respiratory Resistance ◽  
Limited Data ◽  
Flow Paths ◽  
Human Volunteers ◽  
Flow Generator ◽  
Sinusoidal Flow ◽  
Airflow Perturbation Device ◽  
Strong Linear Relationship

The airflow perturbation device (APD) has been developed as a portable, easy to use, and a rapid response instrument for measuring respiratory resistance in humans. However, the APD has limited data validating it against the established techniques. This study used a mechanical system to simulate the normal range of human breathing to validate the APD with the clinically accepted impulse oscillometry (IOS) technique. The validation system consisted of a sinusoidal flow generator with ten standardized resistance configurations that were shown to represent a total range of resistances from 0.12 to 0.95 kPa·L−1·s (1.2–9.7 cm H2O·L−1·s). Impulse oscillometry measurements and APD measurements of the mechanical system were recorded and compared at a constant airflow of 0.15 L·s−1. Both the IOS and APD measurments were accurate in assessing nominal resistance. In addition, a strong linear relationship was observed between APD measurements and IOS measurements (R2 = 0.999). A second series of measurements was made on ten human volunteers with external resistors added in their respiratory flow paths. Once calibrated with the mechanical system, the APD gave respiratory resistance measurements within 5% of IOS measurements. Because of their comparability to IOS measurements, APD measurements are shown to be valid representations of respiratory resistance.

The pumping characteristics of screw rotors. I. The theory of calculation of the pumping capacity of screw rotors

1987 ◽  
Vol 52 (2) ◽  
pp. 357-371 ◽  
Author(s):  
František Rieger
Keyword(s):  
Present State ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Screw Rotor ◽  
Screw Rotors

This paper summarizes the present state of the theory of calculation of the pumping capacity of screw rotors. The calculation starts from the equation for the volumetric flow rate of the flow between two unconfined plates modified by correction coefficients obtained from the relationships for the flow rate in simpler geometrical configurations to which the screw rotor may be, under certain circumstances, reduced.

scholarly journals Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7260
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Blood Viscosity ◽  
Measurement Errors ◽  
Present Method ◽  
Test Fluid ◽  
Constant Flow Rate ◽  
Rbc Aggregation ◽  
Sinusoidal Flow ◽  
Analytical Expressions

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

Pahoehoe and aa in Hawaii: volumetric flow rate controls the lava structure

1990 ◽  
Vol 52 (8) ◽  
pp. 615-628 ◽  
Author(s):  
Scott K Rowland ◽  
George PL Walker
Keyword(s):  
Flow Rate ◽  
Volumetric Flow Rate

Simultaneous Measuring Method for Both Volumetric Flow Rates of Air-Water Mixture Using a Turbine Flowmeter

1996 ◽  
Vol 118 (1) ◽  
pp. 29-35 ◽  
Author(s):  
K. Minemura ◽  
K. Egashira ◽  
K. Ihara ◽  
H. Furuta ◽  
K. Yamamoto
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Oil Field ◽  
Liquid Density ◽  
Water Mixture ◽  
Rotor Speed ◽  
Flow Rates ◽  
Field Development ◽  
Turbine Flowmeter

A turbine flowmeter is employed in this study in connection with offshore oil field development, in order to measure simultaneously both the volumetric flow rates of air-water two-phase mixture. Though a conventional turbine flowmeter is generally used to measure the single-phase volumetric flow rate by obtaining the rotational rotor speed, the method proposed additionally reads the pressure drop across the meter. After the pressure drop and rotor speed measured are correlated as functions of the volumetric flow ratio of the air to the whole fluid and the total volumetric flow rate, both the flow rates are iteratively evaluated with the functions on the premise that the liquid density is known. The evaluated flow rates are confirmed to have adequate accuracy, and thus the applicability of the method to oil fields.

Development of Cooling System for a Large Area at High Heat Flux by Using Flow Boiling in Narrow Channels

2009 ◽  
Author(s):  
Shinichi Miura ◽  
Yukihiro Inada ◽  
Yasuhisa Shinmoto ◽  
Haruhiko Ohta
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Rate ◽  
Mass Velocity ◽  
Cooling System ◽  
Volumetric Flow Rate ◽  
High Heat ◽  
High Heat Flux ◽  
Gap Size ◽  
Heated Channel

Advance of an electronic technology has caused the increase of heat generation density for semiconductors densely integrated. Thermal management becomes more important, and a cooling system for high heat flux is required. It is extremely effective to such a demand using flow boiling heat transfer because of its high heat removal ability. To develop the cooling system for a large area at high heat flux, the cold plate structure of narrow channels with auxiliary unheated channel for additional liquid supply was devised and confirmed its validity by experiments. A large surface of 150mm in heated length and 30mm in width with grooves of an apex angle of 90 deg, 0.5mm depth and 1mm in pitch was employed. A structure of narrow rectangular heated channel between parallel plates with an unheated auxiliary channel was employed and the heat transfer characteristics were examined by using water for different combinations of gap sizes and volumetric flow rates. Five different liquid distribution modes were tested and their data were compared. The values of CHF larger than 1.9×106W/m2 for gap size of 2mm under mass velocity based on total volumetric flow rate and on the cross section area of main heated channel 720kg/m2s or 1.7×106W/m2 for gap size of 5mm under 290kg/m2s were obtained under total volumetric flow rate 4.5×10−5m3/s regardless of the liquid distribution modes. Under several conditions, the extensions of dry-patches were observed at the upstream location of the main heated channel resulting burnout not at the downstream but at the upstream. High values of CHF larger than 2×106W/m2 were obtained only for gap size of 2mm. The result indicates that higher mass velocity in the main heated channel is more effective for the increase in CHF. It was clarified that there is optimum flow rate distribution to obtain the highest values of CHF. For gap size of 2mm, high heat transfer coefficient as much as 7.4×104W/m2K were obtained at heat flux 1.5×106W/m2 under mass velocity 720kg/m2s based on total volumetric flow rate and on the cross section area of main heated channel. Also to obtain high heat transfer coefficient, it is more useful to supply the cooling liquid from the auxiliary unheated channel for additional liquid supply in the transverse direction perpendicular to the flow in the main heated channel.

scholarly journals The Effect of Exercise on Respiratory Resistance in Athletes With and Without Paradoxical Vocal Fold Motion Disorder

2015 ◽  
Vol 24 (3) ◽  
pp. 470-479 ◽  
Author(s):  
Sally J. K. Gallena ◽  
Nancy Pearl Solomon ◽  
Arthur T. Johnson ◽  
Jafar Vossoughi ◽  
Wei Tian
Keyword(s):  
Repeated Measures ◽  
Vocal Fold ◽  
Female Athletes ◽  
Exercise Duration ◽  
Treadmill Running ◽  
Respiratory Resistance ◽  
The Difference ◽  
Airflow Perturbation Device ◽  
Vocal Fold Motion ◽  
Paradoxical Vocal Fold Motion

Purpose An investigational, portable instrument was used to assess inspiratory (R i ) and expiratory (R e ) resistances during resting tidal breathing (RTB), postexercise breathing (PEB), and recovery breathing (RB) in athletes with and without paradoxical vocal fold motion disorder (PVFMD). Method Prospective, controlled, repeated measures within-subject and between-groups design. Twenty-four teenage female athletes, 12 with and 12 without PVFMD, breathed into the Airflow Perturbation Device for baseline measures of respiratory resistance and for two successive 1-min trials after treadmill running for up to 12 min. Exercise duration and dyspnea ratings were collected and compared across groups. Results Athletes with PVFMD had lower than control R i and R e values during RTB that significantly increased at PEB and decreased during RB. Control athletes' R e decreased significantly from RTB to PEB but not from PEB to RB, whereas R i did not change from RTB to PEB but decreased from PEB to RB. Athletes without PVFMD ran longer, providing lower dyspnea ratings. Conclusion Immediately following exercise, athletes with PVFMD experienced increased respiratory resistance that affected their exercise performance. The difference in resting respiratory resistances between groups is intriguing and could point to anatomical differences or neural adaptation in teenagers with PVFMD. The Airflow Perturbation Device appears to be a clinically feasible tool that can provide insight into PVFMD and objective data for tracking treatment progress.

Evaluation of Design Characteristics for Animal Mortality Composting Systems

2021 ◽  
Vol 65 (1) ◽  
pp. 23-30
Author(s):  
Tiago Costa ◽  
Neslihan Akdeniz
Keyword(s):  
Moisture Content ◽  
Linear Relationship ◽  
Compressive Stress ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Airflow Rate ◽  
List Type ◽  
Design Characteristics ◽  
The Impact ◽  
Composting Systems

HighlightsDesign characteristics for animal mortality compost cover materials were tested.Compressive stress was applied to simulate the effects of the mortalities on cover materials.The highest permeability was measured for sawdust at 25% moisture content.A linear relationship was found between the volumetric flow rate and the power required to aerate the piles.Abstract. Composting is an aerobic process that relies on natural aeration to maintain proper oxygen levels. Air-filled porosity, mechanical strength, and permeability are among the essential parameters used to optimize the process. This study’s objective was to measure the physical parameters and airflow characteristics of three commonly used cover materials at four moisture levels, which could be used in designing actively aerated swine mortality composting systems. A laboratory-scale experiment was conducted to measure pressure drops across the cover materials as a function of the airflow rate and the material’s moisture content. Compressive stress was applied for 48 h to simulate the impact of swine mortalities on the cover materials. The power required to aerate each material was determined as a function of volumetric flow rate and moisture content. As expected, air-filled porosity and permeability decreased with increasing bulk density and moisture content. The highest average permeability values were measured at 25% moisture content and ranged from 66 × 10-4 to 70 × 10-4 mm2, from 161 × 10-4 to 209 × 10-4 mm2, and from 481 × 10-4 to 586 × 10-4 mm2 for woodchips, ground cornstalks, and sawdust, respectively. For the range of airflow rates tested in this study (0.0025 to 0.0050 m3 s-1 m-2), a linear relationship (R2 = 0.975) was found between the volumetric flow rate (m3 s-1) and the power required to aerate the compost pile (W per 100 kg of swine mortality). Keywords: Airflow, Darcy’s law, Livestock, Modeling, Permeability, Pressure drop.

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