scholarly journals Comparison of Intraoral and Extraoral Digital Scanners: Evaluation of Surface Topography and Precision

2020 ◽  
Vol 8 (2) ◽  
pp. 52 ◽  
Author(s):  
Sang J. Lee ◽  
Soo-Woo Kim ◽  
Joshua J. Lee ◽  
Chan W. Cheong
Keyword(s):  
Surface Topography ◽  
Reference Model ◽  
Linear Regression Analysis ◽  
Precision Measurements ◽  
Scanning System ◽  
Digital Scanning ◽  
Measurement Surface ◽  
Scanning Mechanism ◽  
Tukey Method ◽  
Posterior Position

The aim of this study was to evaluate the surface topography and the precision measurements of different intraoral and extraoral digital scanners. A reference model of a maxillary arch with four implant analogs was prepared and scanned by three intraoral and two extraoral scanners. The reference model was scanned fifteen times with each digital scanning system, investigating the surface topography and precision measurements for the same-arch and cross-arch measurements. The data was exported to 3D inspection and mesh-processing software (GOM Inspect, Braunschweig, Germany). Statistical analysis was performed using a one-way Analysis of Variance (ANOVA) with the Tukey method for pairwise comparisons. The effect of parameters on generating the surface topography was analyzed by Univariate Linear Regression Analysis. Of the scanner systems evaluated, iTero (IT) exhibited the most number of triangulation points, followed by Trios 3 Shape (TR) and Straumann Cares (SC). There were no significant differences observed in the surface topography when comparing flat and contoured surfaces, the anterior and posterior position, and interproximal areas. For the precision measurement in the same quadrant, no statistical difference was noted between intra- and extraoral scanners. However, the extraoral scanners showed substantially higher precision measurements for the cross-arch measurement. Surface topography did not correlate to precision. Rather, precision correlated with the scanning mechanism. For a quadrant scanning, both intraoral and extraoral scanners are recommended, but extraoral scanners are recommended for a full-arch scanning.

Transoral CO2 laser partial laryngectomies using the digital scanning system

2011 ◽  
Vol 22 (2) ◽  
pp. 122-127 ◽  
Author(s):  
Nayla Matar ◽  
Marc Remacle ◽  
Georges Lawson ◽  
Vincent Bachy
Keyword(s):  
Co2 Laser ◽  
Scanning System ◽  
Digital Scanning

Effects of Combustion Chamber Geometry Upon Exit Temperature Profiles

2009 ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan
Keyword(s):  
Combustion Chamber ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature ◽  
Engine Operating Condition

The purpose of this research was to investigate the effects of combustion chamber geometry on exit temperature fields using an ambient pressure test rig. The apparatus contained a 120° sector of a combustion section of a Rolls Royce (previously Allison) T56-A-15 gas turbine engine. A thermocouple rake acquired high-resolution temperature measurements in the combustion chamber exit plane. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 knots) at 7620 m (25000ft) by matching the Mach number, the equivalence ratio and the Sauter mean diameter of the fuel spray. To quantify the geometric deviations of the combustion chamber specimens, which varied in service conditions, a three-dimensional laser scanning system was used. Combustion chamber geometric deviations were extracted through comparison of the scanned data to a reference model using the selected software. The relationship between combustion chamber exit temperature profile and geometric deviation was then compared. The main conclusion of this research was that small deviations from nominal dimensions in the dilution zone of the combustion chamber correlated to an increase in pattern factor. A decrease in the mixing of the products of combustion and dilution air was observed as damage in the dilution zone increased. This reduction in mixing created a more compact, higher temperature core flow. The results obtained from this research were compared to past studies.

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan ◽  
Asad Asghar
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature

The purpose of this continuing research was to investigate the effects of combustion chamber geometry on exit temperature fields using a validated ambient pressure test rig. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 kn) at 7620 m (25,000 ft) by matching Mach number, equivalence ratio, and Sauter mean diameter of the fuel spray. Using a thermocouple rake, high resolution temperature measurements were obtained in the combustion chamber exit plane. Following the previously published procedures, a three-dimensional laser scanning system was used to quantify geometric deviations from two populations of combustion chambers. These populations differed in that one had a significantly higher allowable engine operating temperature for continuous cruise condition. Geometric deviations of both populations were compared with the reference model. The relationship between combustion chamber exit temperature profile and geometric deviation of each population was then compared. The main conclusion of this research was that the temperature profile degradation of both populations due to geometric deviations followed similar trends. These results highlighted that the difference in operating limitations of these populations did not significantly affect component performance.

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

2010 ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan ◽  
Asad Asghar
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature

The purpose of this continuing research was to investigate the effects of combustion chamber geometry on exit temperature fields using a validated ambient pressure test rig. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 knots) at 7 620 m (25,000 ft) by matching Mach number, equivalence ratio and Sauter mean diameter of the fuel spray. Using a thermocouple rake, high resolution temperature measurements were obtained in the combustion chamber exit plane. Following the previously published procedures, a three-dimensional laser scanning system was used to quantify geometric deviations from two populations of combustion chambers. These populations differed in that one had a significantly higher allowable engine operating temperature for continuous cruise condition. Geometric deviations of both populations were compared to the reference model. The relationship between combustion chamber exit temperature profile and geometric deviation of each population was then compared. The main conclusion of this research was that the temperature profile degradation of both populations due to geometric deviations followed similar trends. These results highlighted that the difference in operating limitations of these populations did not significantly affect component performance.

Scanning system development and digital beam control method for electron beam selective melting

2015 ◽  
Vol 21 (3) ◽  
pp. 313-321 ◽  
Author(s):  
Chao Guo ◽  
Jing Zhang ◽  
Jun Zhang ◽  
Wenjun Ge ◽  
Bo Yao ◽  
...  
Keyword(s):  
Electron Beam ◽  
Large Deflection ◽  
Control Method ◽  
Three Dimensional ◽  
Beam Deflection ◽  
Scanning System ◽  
Content Type ◽  
Metal Parts ◽  
Digital Scanning ◽  
Electron Beam Selective Melting

Purpose – The purpose of this paper is to correct the beam deflection errors and beam defocus by using a digital scanning system. Electron beam selective melting (EBSM) is an additive manufacturing technology for metal parts. Beam deflection errors and beam defocus at large deflection angles would greatly influence the accuracy of the built parts. Design/methodology/approach – The 200 × 200 mm2 scanning area of the electron beam is discretized into 1001 × 1001 points arranged in array, based on which a digital scanning system is developed. To correct the deflection errors, the electron beam scans a 41 × 41 testing grid, and the corrective algorithm is based on the bilinear transformation from the grid points’ nominal coordinates to their measured coordinates. The beam defocus is corrected by a dynamic focusing method. A three-dimensional testing part is built with and without using the corrective algorithm, and their accuracies are quantitatively compared. Findings – The testing grid scanning result shows that the accuracy of the corrected beam deflection system is better than ± 0.2 mm and beam defocus at large deflection angles is eliminated visibly. The testing part built with using the corrective algorithm is of greater accuracy than the one built without using it. Originality/value – Benefiting from the digital beam control method, the model-to-part accuracy of the system is effectively improved. The digital scanning system is feasible in rapid manufacturing large and complex three-dimensional metal parts.

scholarly journals DScan – a high-performance digital scanning system for entomological collections

ZooKeys ◽  
2012 ◽  
Vol 209 ◽  
pp. 183-191 ◽  
Author(s):  
Stefan Schmidt ◽  
Michael Balke ◽  
Stefan Lafogler
Keyword(s):  
High Performance ◽  
Scanning System ◽  
Digital Scanning

A Method to Get Template for Ultrasonic Inspection

2014 ◽  
Vol 926-930 ◽  
pp. 1566-1570
Author(s):  
Yun Qiu Gong ◽  
Yang Zhang
Keyword(s):  
Surface Reconstruction ◽  
Coordinate Transformation ◽  
Ultrasonic Inspection ◽  
Ultrasonic Measurement ◽  
Scanning System ◽  
Cad Model ◽  
Specific Process ◽  
Kinematics Modeling ◽  
Measurement Surface

In order to avoid getting the CAD model of the workpiece repeatedly in ultrasonic inspection, we use a few measurement points on the workpiece and the template to match the position, and use coordinate transformation in CAD template to quickly generate CAD model of the workpiece under test in the scanning system. In this paper, several aspects such as kinematics modeling for mechanical arm, ultrasonic measurement, surface reconstruction and profiling measurement are studied to introduce the specific process of getting a detection template.

The Broad Applications of the Scanning Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 20-21
Author(s):  
C. T. Nightingale ◽  
S. E. Summers ◽  
T. P. Turnbull
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscopy ◽  
Surface Topography ◽  
Great Depth ◽  
Resolving Power ◽  
Depth Of Field ◽  
Pictorial Representations ◽  
Scanning Electron

The ease of operation of the scanning electron microscope has insured its wide application in medicine and industry. The micrographs are pictorial representations of surface topography obtained directly from the specimen. The need to replicate is eliminated. The great depth of field and the high resolving power provide far more information than light microscopy.

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