The Identification of the Potential Limitations of Acoustic Rhinometery Using Computer-Generated, Three-Dimensional Reconstructions of Simple Models

1996 ◽  
Vol 10 (2) ◽  
pp. 77-82 ◽  
Author(s):  
A. Tomkinson ◽  
R. Eccles
Keyword(s):  
Nasal Cavity ◽  
Three Dimensional ◽  
Internal Surface ◽  
Three Dimensions ◽  
Gradual Change ◽  
Large Area ◽  
Cross Sectional ◽  
Wave Path ◽  
Acoustic Evaluation ◽  
Set Up

The internal surface of the nasal cavity is geometrically complicated and does not lend itself readily to direct measurement. Simple geometric shapes were used as a model for changes in the nasal cavity. Following the introduction of specific changes to a particular system, the effect of these changes on the acoustic evaluation of the space was studied. Cylinders were chosen, as the wave path could be assumed to be perpendicular to the model surface. The acoustic rhinometer's accuracy was assessed in the presence of small and large variations in cross sectional area, in the presence of a series of consecutive area changes, and a gradual change in diameter. The effect of the introduction of acoustic leak was also modelled. The acoustic data acquired from these models was used to reconstruct the model in three dimensions. These reconstructions were compared to the original model. The acoustic rhinometer was found to resolve with reasonable accuracy the dimensions of small spaces; however, if regions of sudden large area changes were present in the space, the data beyond these regions was highly unreliable. Furthermore, the presence of acoustic leak in a system had a similar effect. Unless precautions are taken in the set-up and operation of the acoustic rhinometer, the potential for misinterpretation of data and the introduction of bias is very high.

scholarly journals A Comprehensive Observational Study of Graupel and Hail Terminal Velocity, Mass Flux, and Kinetic Energy

2018 ◽  
Vol 75 (11) ◽  
pp. 3861-3885 ◽  
Author(s):  
Andrew Heymsfield ◽  
Miklós Szakáll ◽  
Alexander Jost ◽  
Ian Giammanco ◽  
Robert Wright
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
Mass Flux ◽  
Three Dimensional ◽  
Acrylonitrile Butadiene Styrene ◽  
Terminal Velocity ◽  
Three Dimensions ◽  
Cross Sectional ◽  
Wide Range ◽  
3D Volume

Abstract This study uses novel approaches to estimate the fall characteristics of hail, covering a size range from about 0.5 to 7 cm, and the drag coefficients of lump and conical graupel. Three-dimensional (3D) volume scans of 60 hailstones of sizes from 2.5 to 6.7 cm were printed in three dimensions using acrylonitrile butadiene styrene (ABS) plastic, and their terminal velocities were measured in the Mainz, Germany, vertical wind tunnel. To simulate lump graupel, 40 of the hailstones were printed with maximum dimensions of about 0.2, 0.3, and 0.5 cm, and their terminal velocities were measured. Conical graupel, whose three dimensions (maximum dimension 0.1–1 cm) were estimated from an analytical representation and printed, and the terminal velocities of seven groups of particles were measured in the tunnel. From these experiments, with printed particle densities from 0.2 to 0.9 g cm−3, together with earlier observations, relationships between the drag coefficient and the Reynolds number and between the Reynolds number and the Best number were derived for a wide range of particle sizes and heights (pressures) in the atmosphere. This information, together with the combined total of more than 2800 hailstones for which the mass and the cross-sectional area were measured, has been used to develop size-dependent relationships for the terminal velocity, the mass flux, and the kinetic energy of realistic hailstones.

scholarly journals Automated Confocal Laser Scanning Microscopy and Semiautomated Image Processing for Analysis of Biofilms

1998 ◽  
Vol 64 (11) ◽  
pp. 4115-4127 ◽  
Author(s):  
Martin Kuehn ◽  
Martina Hausner ◽  
Hans-Joachim Bungartz ◽  
Michael Wagner ◽  
Peter A. Wilderer ◽  
...  
Keyword(s):  
Image Analysis ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Image Acquisition ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Three Dimensions ◽  
Confocal Laser ◽  
Cross Sectional ◽  
In Situ Conditions

ABSTRACT The purpose of this study was to develop and apply a quantitative optical method suitable for routine measurements of biofilm structures under in situ conditions. A computer program was designed to perform automated investigations of biofilms by using image acquisition and image analysis techniques. To obtain a representative profile of a growing biofilm, a nondestructive procedure was created to study and quantify undisturbed microbial populations within the physical environment of a glass flow cell. Key components of the computer-controlled processing described in this paper are the on-line collection of confocal two-dimensional (2D) cross-sectional images from a preset 3D domain of interest followed by the off-line analysis of these 2D images. With the quantitative extraction of information contained in each image, a three-dimensional reconstruction of the principal biological events can be achieved. The program is convenient to handle and was generated to determine biovolumes and thus facilitate the examination of dynamic processes within biofilms. In the present study, Pseudomonas fluorescens or a green fluorescent protein-expressing Escherichia coli strain, EC12, was inoculated into glass flow cells and the respective monoculture biofilms were analyzed in three dimensions. In this paper we describe a method for the routine measurements of biofilms by using automated image acquisition and semiautomated image analysis.

Acoustic rhinometry: validation by three-dimensionally reconstructed computer tomographic scans

2000 ◽  
Vol 89 (3) ◽  
pp. 1013-1021 ◽  
Author(s):  
Hendrik Terheyden ◽  
Steffen Maune ◽  
Jürgen Mertens ◽  
Ole Hilberg
Keyword(s):  
Nasal Cavity ◽  
Linear Regression Analysis ◽  
Three Dimensional ◽  
Acoustic Rhinometry ◽  
Single Subject ◽  
Three Dimensional Model ◽  
Head Region ◽  
Cross Sectional ◽  
Air Volume ◽  
Ct Data

The aim of the present study was a validation of acoustic rhinometry (AR) by computed tomography (CT). Six healthy subjects were examined by CT and AR. The CT data were processed in a computer program (AutoCAD), and a virtual three-dimensional model of each nasal cavity was constructed. This model permitted an individual prediction of the center line of the sound wave propagation through the air volume of the nasal cavity with the cross-sectional areas oriented perpendicularly to this line. The area-distance curves derived from AR and CT were compared. Linear regression analysis revealed a reasonable agreement of AR and CT in the anterior nose below a mean of 6 cm distance from the nostrils [ r = 0.839, P < 0.01, m = 1.123, b= −0.113 (AR = m × CT + b)]. The measuring accuracy using CT as gold standard revealed a mean error at the nasal valve of <0.01 cm2 (4.52%) and at the nasal isthmus of 0.02 cm2 (1.87%). Beyond 6 cm, the correlation decreased ( r = 0.419), and overestimation of the true area occurred (>100%). In conclusion, the measurements were reasonably accurate for diagnostic use up to the turbinate head region. Certain factors induce an overestimation of the true areas beyond this region. However, these factors are constant and reproducible in a single subject, and intraindividual comparative measurements are possible beyond the turbinate head region.

Creation of a standardized geometry of the human nasal cavity

2009 ◽  
Vol 106 (3) ◽  
pp. 784-795 ◽  
Author(s):  
Y. Liu ◽  
M. R. Johnson ◽  
E. A. Matida ◽  
S. Kherani ◽  
J. Marsan
Keyword(s):  
Nasal Cavity ◽  
Three Dimensional ◽  
Ct Scans ◽  
Physical Parameters ◽  
Specific Procedure ◽  
Image Processing Algorithm ◽  
Cross Sectional ◽  
Nasal Airways ◽  
Numerical Studies ◽  
Inhaled Aerosols

A novel, standardized geometry of the human nasal cavity was created by aligning and processing 30 sets of computed tomography (CT) scans of nasal airways of healthy subjects. Digital three-dimensional (3-D) geometries of the 60 single human nasal cavities (30 right and 30 mirrored left cavities) were generated from the CT scans and measurements of physical parameters of each single nasal cavity were performed. A methodology was developed to scale, orient, and align the nasal geometries, after which 2-D digital coronal cross-sectional slices were generated. With the use of an innovative image processing algorithm, median cross-sectional geometries were created to match median physical parameters while retaining the unique geometric features of the human nasal cavity. From these idealized 2-D images, an original 3-D standardized median human nasal cavity was created. This new standardized geometry was compared against the original geometries of all subjects as well as limited existing data from the literature. The new model has potential for use as a geometric standard in future experimental and numerical studies of deposition of inhaled aerosols, as well as for use as a reference during diagnosis of unhealthy patients. The specific procedure developed could also be applied to build standard nasal geometries for different identifiable groups within the larger population.

Measurement of three-dimensional lung tree structures by using computed tomography

1995 ◽  
Vol 79 (5) ◽  
pp. 1687-1697 ◽  
Author(s):  
S. A. Wood ◽  
E. A. Zerhouni ◽  
J. D. Hoford ◽  
E. A. Hoffman ◽  
W. Mitzner
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Central Axis ◽  
Segment Length ◽  
Cross Sectional ◽  
Tree Structures ◽  
Branch Segment ◽  
Tomography Data

A method was devised to computationally segment and measure three-dimensional pulmonary trees in situ. Bronchi and pulmonary vessels were computationally extracted from volumetric computed tomography data based on radiopacity differences between airway wall and airway lumen and between blood and parenchyma, respectively. The tree was reduced to a central axis to facilitate measurement of branch segment length and angle. Cross-sectional area was measured on a reconstructed computed tomography slice perpendicular to this central axis. The method was validated by scanning two Plexiglas phantoms and an intact lung. Reconstructed diameters in the phantoms were accurate for branches > 2 mm. In the lung airway branches between 1 and 2 mm in diameter were often unresolved when their angle of orientation with respect to the axis of the scanner was > 45 degrees. However, if a branch was resolved, its reconstructed diameter was little affected by orientation. This method represents a significant improvement in the analysis of complex pulmonary structures in three dimensions.

Relationship of Challenge and Hindrance Stressors With Burnout and Its Three Dimensions

2015 ◽  
Vol 14 (4) ◽  
pp. 203-212 ◽  
Author(s):  
Angus Yongheng Yao ◽  
Muhammad Jamal ◽  
Evangelia Demerouti
Keyword(s):  
Emotional Exhaustion ◽  
Positive Relationship ◽  
Life Stage ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Two Dimensional ◽  
Cross Sectional ◽  
Cross Sectional Studies ◽  
Relationship Of

Abstract. The two-dimensional-work-stressor framework suggests that both challenge stressors and hindrance stressors have an undesirable (positive) relationship with burnout for all employees. However, the existing studies testing this framework either treated burnout as a global construct or used one burnout dimension and have not used age as a possible moderator. This paper reports two cross-sectional studies that examined the stressor-burnout relationship while burnout is conceptualized as three-dimensional (i.e., emotional exhaustion, cynicism, and inefficacy). Results indicate that although challenge and hindrance stressors show a similar (positive) relationship with exhaustion, they have differing relationships with cynicism and inefficacy. This study also explored how life stage influences the relationships between the two stressors and emotional exhaustion, cynicism, and inefficacy.

scholarly journals <i>Introduction</i>The Cluster mission

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1197-1200 ◽  
Author(s):  
C. P. Escoubet ◽  
M. Fehringer ◽  
M. Goldstein
Keyword(s):  
Three Dimensional ◽  
Distribution Functions ◽  
Three Dimensions ◽  
Small Scale ◽  
Physical Parameters ◽  
Ion Distribution ◽  
Space Operations ◽  
Science Operations ◽  
Electric And Magnetic Fields ◽  
Set Up

Abstract. The Cluster mission, ESA’s first cornerstone project, together with the SOHO mission, dating back to the first proposals in 1982, was finally launched in the summer of 2000. On 16 July and 9 August, respectively, two Russian Soyuz rockets blasted off from the Russian cosmodrome in Baikonour to deliver two Cluster spacecraft, each into their proper orbit. By the end of August 2000, the four Cluster satellites had reached their final tetrahedral constellation. The commissioning of 44 instruments, both individually and as an ensemble of complementary tools, was completed five months later to ensure the optimal use of their combined observational potential. On 1 February 2001, the mission was declared operational. The main goal of the Cluster mission is to study the small-scale plasma structures in three dimensions in key plasma regions, such as the solar wind, bow shock, magnetopause, polar cusps, magnetotail and the auroral zones. With its unique capabilities of three-dimensional spatial resolution, Cluster plays a major role in the International Solar Terrestrial Program (ISTP), where Cluster and the Solar and Heliospheric Observatory (SOHO) are the European contributions. Cluster’s payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields from the quasi-static up to high frequencies, and electron and ion distribution functions from energies of nearly 0 eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC), at the Rutherford Appleton Laboratory (UK), and implemented by the European Space Operations Centre (ESOC), in Darmstadt, Germany. A network of eight national data centres has been set up for raw data processing, for the production of physical parameters, and their distribution to end users all over the world. The latest information on the Cluster mission can be found at http://sci.esa.int/cluster/.

scholarly journals Gauges in three-dimensional gravity and holographic fluids

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Luca Ciambelli ◽  
Charles Marteau ◽  
P. Marios Petropoulos ◽  
Romain Ruzziconi
Keyword(s):  
Three Dimensional ◽  
Three Dimensions ◽  
De Sitter ◽  
Global Properties ◽  
Dimensional Gravity ◽  
Preliminary Study ◽  
Set Up ◽  
Holographic Reconstruction

Abstract Solutions to Einstein’s vacuum equations in three dimensions are locally maximally symmetric. They are distinguished by their global properties and their investigation often requires a choice of gauge. Although analyses of this sort have been performed abundantly, several relevant questions remain. These questions include the interplay between the standard Bondi gauge and the Eddington-Finkelstein type of gauge used in the fluid/gravity holographic reconstruction of these spacetimes, as well as the Fefferman-Graham gauge, when available i.e. in anti de Sitter. The goal of the present work is to set up a thorough dictionary for the available descriptions with emphasis on the relativistic or Carrollian holographic fluids, which portray the bulk from the boundary in anti-de Sitter or flat instances. A complete presentation of residual diffeomorphisms with a preliminary study of their algebra accompanies the situations addressed here.

Visualizing the Pediatric Airway: Three-Dimensional Modeling of Endoscopic Images

1996 ◽  
Vol 105 (1) ◽  
pp. 12-17 ◽  
Author(s):  
Michael E. Dunham ◽  
Rosalee N. Wolf
Keyword(s):  
Video Recording ◽  
Three Dimensional ◽  
Vocal Folds ◽  
Three Dimensions ◽  
Cross Sectional ◽  
Pediatric Airway ◽  
Airway Lumen ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Complex Anatomy

Three-dimensional reconstruction of medical images has emerged as an important visualization tool for studying complex anatomy. These tools have found important applications in neurology and plastic surgery using computed tomography (CT) and magnetic resonance imaging (MRI) data. However, CT and MRI do not sufficiently delineate lesions of the pediatric airway. Inspection through the rod lens telescope remains the standard diagnostic method. A video recording of an endoscopic procedure is essentially a sequence of two-dimensional images captured as the telescope traverses the airway lumen. Using digitized endoscopic video recordings and computer graphics reconstruction techniques, we have developed a preliminary three-dimensional modeling system for the pediatric airway. A series of normal and abnormal telescopic airway examinations were video recorded. Serial sections were obtained by digitizing the video images at uniform intervals as the scope traversed the airway lumen between the vocal folds and the carina. The digitized images were calibrated and used to reconstruct the airway lumen in three dimensions. Classifying airway abnormalities according to the minimal cross-sectional area or with descriptive terms can be subjective and dependent on the endoscopist's observational skills. We hope that this preliminary work will lead to more precise and understandable methods for representing complex airway lesions.

Analysis of Finite Element and Experimental Study on Elastic Body of the Grip Force Sensor

2013 ◽  
Vol 760-762 ◽  
pp. 1012-1016
Author(s):  
Shun Yan ◽  
Chang Ming Wang ◽  
Jian Dong Bao ◽  
Bo Xia He
Keyword(s):  
Finite Element ◽  
Grip Force ◽  
Three Dimensional ◽  
Force Sensor ◽  
Three Dimensions ◽  
Key Points ◽  
New Type ◽  
Characteristic Values ◽  
Set Up ◽  
The Relationship

A three-dimensional grip force sensor with new elastomer structure is developed. By using the simulation of finite element method, the relationship between force and strain is analyzed, the characteristic values of the key points is extracted and the coupling performance between dimensions of grip force sensor is analyzed. The static calibration system is set up and the decoupling matrix of grip force sensor is obtained. Experimental results shows that the new type sensor can eliminate the coupling among the three dimensions effectively.

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