Limits of Active Laser Triangulation as an Instrument for High Precision Plant Imaging

PubMed Central

Paulus, Stefan; Eichert, Thomas; Goldbach, Heiner E.; Kuhlmann, Heiner

2014-01-01

Laser scanning is a non-invasive method for collecting and parameterizing 3D data of well reflecting objects. These systems have been used for 3D imaging of plant growth and structure analysis. A prerequisite is that the recorded signals originate from the true plant surface. In this paper we studied the effects of species, leaf chlorophyll content and sensor settings on the suitability and accuracy of a commercial 660 nm active laser triangulation scanning device. We found that surface images of Ficus benjamina leaves were inaccurate at low chlorophyll concentrations and a long sensor exposure time. Imaging of the rough waxy leaf surface of leek (Allium porrum) was possible using very low exposure times, whereas at higher exposure times penetration and multiple refraction prevented the correct imaging of the surface. A comparison of scans with varying exposure time enabled the target-oriented analysis to identify chlorotic, necrotic and healthy leaf areas or mildew infestations. We found plant properties and sensor settings to have a strong influence on the accuracy of measurements. These interactions have to be further elucidated before laser imaging of plants is possible with the high accuracy required for e.g., the observation of plant growth or reactions to water stress. PMID:24504106

3D Laser Triangulation for Plant Phenotyping in Challenging Environments

PubMed Central

Kjaer, Katrine Heinsvig; Ottosen, Carl-Otto

2015-01-01

To increase the understanding of how the plant phenotype is formed by genotype and environmental interactions, simple and robust high-throughput plant phenotyping methods should be developed and considered. This would not only broaden the application range of phenotyping in the plant research community, but also increase the ability for researchers to study plants in their natural environments. By studying plants in their natural environment in high temporal resolution, more knowledge on how multiple stresses interact in defining the plant phenotype could lead to a better understanding of the interaction between plant responses and epigenetic regulation. In the present paper, we evaluate a commercial 3D NIR-laser scanner (PlantEye, Phenospex B.V., Herleen, The Netherlands) to track daily changes in plant growth with high precision in challenging environments. Firstly, we demonstrate that the NIR laser beam of the scanner does not affect plant photosynthetic performance. Secondly, we demonstrate that it is possible to estimate phenotypic variation amongst the growth pattern of ten genotypes of Brassica napus L. (rapeseed), using a simple linear correlation between scanned parameters and destructive growth measurements. Our results demonstrate the high potential of 3D laser triangulation for simple measurements of phenotypic variation in challenging environments and in a high temporal resolution. PMID:26066990

3D Geometrical Inspection of Complex Geometry Parts Using a Novel Laser Triangulation Sensor and a Robot

PubMed Central

Brosed, Francisco Javier; Aguilar, Juan José; Guillomía, David; Santolaria, Jorge

2011-01-01

This article discusses different non contact 3D measuring strategies and presents a model for measuring complex geometry parts, manipulated through a robot arm, using a novel vision system consisting of a laser triangulation sensor and a motorized linear stage. First, the geometric model incorporating an automatic simple module for long term stability improvement will be outlined in the article. The new method used in the automatic module allows the sensor set up, including the motorized linear stage, for the scanning avoiding external measurement devices. In the measurement model the robot is just a positioning of parts with high repeatability. Its position and orientation data are not used for the measurement and therefore it is not directly “coupled” as an active component in the model. The function of the robot is to present the various surfaces of the workpiece along the measurement range of the vision system, which is responsible for the measurement. Thus, the whole system is not affected by the robot own errors following a trajectory, except those due to the lack of static repeatability. For the indirect link between the vision system and the robot, the original model developed needs only one first piece measuring as a “zero” or master piece, known by its accurate measurement using, for example, a Coordinate Measurement Machine. The strategy proposed presents a different approach to traditional laser triangulation systems on board the robot in order to improve the measurement accuracy, and several important cues for self-recalibration are explored using only a master piece. Experimental results are also presented to demonstrate the technique and the final 3D measurement accuracy. PMID:22346569

Application of Blue Laser Triangulation Sensors for Displacement Measurement Through Fire.

PubMed

Hoehler, Matthew S; Smith, Christopher M

2016-11-01

This paper explores the use of blue laser triangulation sensors to measure displacement of a target located behind or in the close proximity of natural gas diffusion flames. This measurement is critical for providing high-quality data in structural fire tests. The position of the laser relative to the flame envelope can significantly affect the measurement scatter, but has little influence on the mean values. We observe that the measurement scatter is normally distributed and increases linearly with the distance of the target from the flame along the beam path. Based on these observations, we demonstrate how time-averaging can be used to achieve a standard uncertainty associated with the displacement error of less than 0.1 mm, which is typically sufficient for structural fire testing applications. Measurements with the investigated blue laser sensors were not impeded by the thermal radiation emitted from the flame or the soot generated from the relatively clean-burning natural gas.

A fast high-precision six-degree-of-freedom relative position sensor

NASA Astrophysics Data System (ADS)

Hughes, Gary B.; Macasaet, Van P.; Griswold, Janelle; Sison, Claudia A.; Lubin, Philip; Meinhold, Peter; Suen, Jonathan; Brashears, Travis; Zhang, Qicheng; Madajian, Jonathan

2016-03-01

Lasers are commonly used in high-precision measurement and profiling systems. Some laser measurement systems are based on interferometry principles, and others are based on active triangulation, depending on requirements of the application. This paper describes an active triangulation laser measurement system for a specific application wherein the relative position of two fixed, rigid mechanical components is to be measured dynamically with high precision in six degrees of freedom (DOF). Potential applications include optical systems with feedback to control for mechanical vibration, such as target acquisition devices with multiple focal planes. The method uses an array of several laser emitters mounted on one component. The lasers are directed at a reflective surface on the second component. The reflective surface consists of a piecewise-planar pattern such as a pyramid, or more generally a curved reflective surface such as a hyperbolic paraboloid. The reflected spots are sensed at 2-dimensional photodiode arrays on the emitter component. Changes in the relative position of the emitter component and reflective surface will shift the location of the reflected spots within photodiode arrays. Relative motion in any degree of freedom produces independent shifts in the reflected spot locations, allowing full six-DOF relative position determination between the two component positions. Response time of the sensor is limited by the read-out rate of the photodiode arrays. Algorithms are given for position determination with limits on uncertainty and sensitivity, based on laser and spot-sensor characteristics, and assuming regular surfaces. Additional uncertainty analysis is achievable for surface irregularities based on calibration data.

Blind guidance system based on laser triangulation

NASA Astrophysics Data System (ADS)

Wu, Jih-Huah; Wang, Jinner-Der; Fang, Wei; Lee, Yun-Parn; Shan, Yi-Chia; Kao, Hai-Ko; Ma, Shih-Hsin; Jiang, Joe-Air

2012-05-01

We propose a new guidance system for the blind. An optical triangulation method is used in the system. The main components of the proposed system comprise of a notebook computer, a camera, and two laser modules. The track image of the light beam on the ground or on the object is captured by the camera and then the image is sent to the notebook computer for further processing and analysis. Using a developed signal-processing algorithm, our system can determine the object width and the distance between the object and the blind person through the calculation of the light line positions on the image. A series of feasibility tests of the developed blind guidance system were conducted. The experimental results show that the distance between the test object and the blind can be measured with a standard deviation of less than 8.5% within the range of 40 and 130 cm, while the test object width can be measured with a standard deviation of less than 4.5% within the range of 40 and 130 cm. The application potential of the designed system to the blind guidance can be expected.

The use of triangulation in qualitative research.

PubMed

Carter, Nancy; Bryant-Lukosius, Denise; DiCenso, Alba; Blythe, Jennifer; Neville, Alan J

2014-09-01

Triangulation refers to the use of multiple methods or data sources in qualitative research to develop a comprehensive understanding of phenomena (Patton, 1999). Triangulation also has been viewed as a qualitative research strategy to test validity through the convergence of information from different sources. Denzin (1978) and Patton (1999) identified four types of triangulation: (a) method triangulation, (b) investigator triangulation, (c) theory triangulation, and (d) data source triangulation. The current article will present the four types of triangulation followed by a discussion of the use of focus groups (FGs) and in-depth individual (IDI) interviews as an example of data source triangulation in qualitative inquiry.

Spacecraft hazard avoidance utilizing structured light

NASA Technical Reports Server (NTRS)

Liebe, Carl Christian; Padgett, Curtis; Chapsky, Jacob; Wilson, Daniel; Brown, Kenneth; Jerebets, Sergei; Goldberg, Hannah; Schroeder, Jeffrey

2006-01-01

At JPL, a <5 kg free-flying micro-inspector spacecraft is being designed for host-vehicle inspection. The spacecraft includes a hazard avoidance sensor to navigate relative to the vehicle being inspected. Structured light was selected for hazard avoidance because of its low mass and cost. Structured light is a method of remote sensing 3-dimensional structure of the proximity utilizing a laser, a grating, and a single regular APS camera. The laser beam is split into 400 different beams by a grating to form a regular spaced grid of laser beams that are projected into the field of view of an APS camera. The laser source and the APS camera are separated forming the base of a triangle. The distance to all beam intersections of the host are calculated based on triangulation.

Possibility of using NURBS for surface plotting by survey data

NASA Astrophysics Data System (ADS)

Pravdina, E. A.; Lepikhina, O. J.

2018-05-01

Different methods of surface plotting were discussed in this article. Constructing the surface with the help of the Delaunay triangulation algorithm is described. The TIN-surfaces (triangles irregular net) method is used in the entire CAD software. This type of surfaces is plotting by results of laser scanning and stadia surveying. Possibility of using spline surfaces (NURBS) for surface plotting is studied. For a defined number of points by Mathcad software, the curvilinear function that described two-dimensional spline surfaces was calculated and plotted.

Calibration Methods for a 3D Triangulation Based Camera

NASA Astrophysics Data System (ADS)

Schulz, Ulrike; Böhnke, Kay

A sensor in a camera takes a gray level image (1536 x 512 pixels), which is reflected by a reference body. The reference body is illuminated by a linear laser line. This gray level image can be used for a 3D calibration. The following paper describes how a calibration program calculates the calibration factors. The calibration factors serve to determine the size of an unknown reference body.

Triangulation Based 3D Laser Imaging for Fracture Orientation Analysis

NASA Astrophysics Data System (ADS)

Mah, J.; Claire, S.; Steve, M.

2009-05-01

Laser imaging has recently been identified as a potential tool for rock mass characterization. This contribution focuses on the application of triangulation based, short-range laser imaging to determine fracture orientation and surface texture. This technology measures the distance to the target by triangulating the projected and reflected laser beams, and also records the reflection intensity. In this study, we acquired 3D laser images of rock faces using the Laser Camera System (LCS), a portable instrument developed by Neptec Design Group (Ottawa, Canada). The LCS uses an infrared laser beam and is immune to the lighting conditions. The maximum image resolution is 1024 x 1024 volumetric image elements. Depth resolution is 0.5 mm at 5 m. An above ground field trial was conducted at a blocky road cut with well defined joint sets (Kingston, Ontario). An underground field trial was conducted at the Inco 175 Ore body (Sudbury, Ontario) where images were acquired in the dark and the joint set features were more subtle. At each site, from a distance of 3 m away from the rock face, a grid of six images (approximately 1.6 m by 1.6 m) was acquired at maximum resolution with 20% overlap between adjacent images. This corresponds to a density of 40 image elements per square centimeter. Polyworks, a high density 3D visualization software tool, was used to align and merge the images into a single digital triangular mesh. The conventional method of determining fracture orientations is by manual measurement using a compass. In order to be accepted as a substitute for this method, the LCS should be capable of performing at least to the capabilities of manual measurements. To compare fracture orientation estimates derived from the 3D laser images to manual measurements, 160 inclinometer readings were taken at the above ground site. Three prominent joint sets (strike/dip: 236/09, 321/89, 325/01) were identified by plotting the joint poles on a stereonet. Underground, two main joint sets (strike/dip: 060/00, 114/86) were identified from 49 manual inclinometer measurements A stereonet of joint poles from the 3D laser data was generated using the commercial software Split-FX. Joint sets were identified successfully and their orientations correlated well with the hand measurements. However, Split-Fx overlays a simply 2D grid of equal-sized triangles onto the 3D surface and requires significant user input. In a more automated approach, we have developed a MATLAB script which directly imports the Polyworks 3D triangular mesh. A typical mesh is composed of over 1 million triangles of variable sizes: smooth regions are represented by large triangles, whereas rough surfaces are captured by several smaller triangles. Using the triangle vertices, the script computes the strike and dip of each triangle. This approach opens possibilities for statistical analysis of a large population of fracture orientation estimates, including surface texture. The methodology will be used to evaluate both synthetic and field data.

The research and development of the non-contact detection of the tubing internal thread with a line structured light

NASA Astrophysics Data System (ADS)

Hu, Yuanyuan; Xu, Yingying; Hao, Qun; Hu, Yao

2013-12-01

The tubing internal thread plays an irreplaceable role in the petroleum equipment. The unqualified tubing can directly lead to leakage, slippage and bring huge losses for oil industry. For the purpose of improving efficiency and precision of tubing internal thread detection, we develop a new non-contact tubing internal thread measurement system based on the laser triangulation principle. Firstly, considering that the tubing thread had a small diameter and relatively smooth surface, we built a set of optical system with a line structured light to irradiate the internal thread surface and obtain an image which contains the internal thread profile information through photoelectric sensor. Secondly, image processing techniques were used to do the edge detection of the internal thread from the obtained image. One key method was the sub-pixel technique which greatly improved the detection accuracy under the same hardware conditions. Finally, we restored the real internal thread contour information on the basis of laser triangulation method and calculated tubing thread parameters such as the pitch, taper and tooth type angle. In this system, the profile of several thread teeth can be obtained at the same time. Compared with other existing scanning methods using point light and stepper motor, this system greatly improves the detection efficiency. Experiment results indicate that this system can achieve the high precision and non-contact measurement of the tubing internal thread.

Validation of Noninvasive MOEMS-Assisted Measurement System Based on CCD Sensor for Radial Pulse Analysis

PubMed Central

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-01-01

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner′s subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation. PMID:23609803

Validation of noninvasive MOEMS-assisted measurement system based on CCD sensor for radial pulse analysis.

PubMed

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-04-22

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner's subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation.

Applications of lasers to production metrology, control, and machine 'Vision'

NASA Astrophysics Data System (ADS)

Pryor, T. R.; Erf, R. K.; Gara, A. D.

1982-06-01

General areas of laser application to production measurement and inspection are reviewed together with the associated laser measurement techniques. The topics discussed include dimensional gauging of part profiles using laser imaging or scanning techniques, laser triangulation for surface contour measurement, surface finish measurement and defect inspection, holography and speckle techniques, and strain measurement. The emerging field of robot guidance utilizing lasers and other sensing means is examined, and, finally, the use of laser marking and reading equipment is briefly discussed.

Sub-pixel accuracy thickness calculation of poultry fillets from scattered laser profiles

NASA Astrophysics Data System (ADS)

Jing, Hansong; Chen, Xin; Tao, Yang; Zhu, Bin; Jin, Fenghua

2005-11-01

A laser range imaging system based on the triangulation method was designed and implemented for online high-resolution thickness calculation of poultry fillets. A laser pattern was projected onto the surface of the chicken fillet for calculation of the thickness of the meat. Because chicken fillets are relatively loosely-structured material, a laser light easily penetrates the meat, and scattering occurs both at and under the surface. When laser light is scattered under the surface it is reflected back and further blurs the laser line sharpness. To accurately calculate the thickness of the object, the light transportation has to be considered. In the system, the Bidirectional Reflectance Distribution Function (BSSRDF) was used to model the light transportation and the light pattern reflected into the cameras. BSSRDF gives the reflectance of a target as a function of illumination geometry and viewing geometry. Based on this function, an empirical method has been developed and it has been proven that this method can be used to accurately calculate the thickness of the object from a scattered laser profile. The laser range system is designed as a sub-system that complements the X-ray bone inspection system for non-invasive detection of hazardous materials in boneless poultry meat with irregular thickness.

Application of blue laser triangulation sensors for displacement measurement through fire

NASA Astrophysics Data System (ADS)

Hoehler, Matthew S.; Smith, Christopher M.

2016-11-01

This paper explores the use of blue laser triangulation sensors to measure displacement of a target located behind or in the close proximity of natural gas diffusion flames. This measurement is critical for providing high-quality data in structural fire tests. The position of the laser relative to the flame envelope can significantly affect the measurement scatter, but has little influence on the mean values. We observe that the measurement scatter is normally distributed and increases linearly with the distance of the target from the flame along the beam path. Based on these observations, we demonstrate how time-averaging can be used to achieve a standard uncertainty associated with the displacement error of less than 0.1 mm, which is typically sufficient for structural fire testing applications. Measurements with the investigated blue laser sensors were not impeded by the thermal radiation emitted from the flame or the soot generated from the relatively clean-burning natural gas.

Application of Blue Laser Triangulation Sensors for Displacement Measurement Through Fire

PubMed Central

Hoehler, Matthew S.; Smith, Christopher M.

2016-01-01

This paper explores the use of blue laser triangulation sensors to measure displacement of a target located behind or in the close proximity of natural gas diffusion flames. This measurement is critical for providing high-quality data in structural fire tests. The position of the laser relative to the flame envelope can significantly affect the measurement scatter, but has little influence on the mean values. We observe that the measurement scatter is normally distributed and increases linearly with the distance of the target from the flame along the beam path. Based on these observations, we demonstrate how time-averaging can be used to achieve a standard uncertainty associated with the displacement error of less than 0.1 mm, which is typically sufficient for structural fire testing applications. Measurements with the investigated blue laser sensors were not impeded by the thermal radiation emitted from the flame or the soot generated from the relatively clean-burning natural gas. PMID:28066131

Three-dimensional optical reconstruction of vocal fold kinematics using high-speed video with a laser projection system

PubMed Central

Luegmair, Georg; Mehta, Daryush D.; Kobler, James B.; Döllinger, Michael

2015-01-01

Vocal fold kinematics and its interaction with aerodynamic characteristics play a primary role in acoustic sound production of the human voice. Investigating the temporal details of these kinematics using high-speed videoendoscopic imaging techniques has proven challenging in part due to the limitations of quantifying complex vocal fold vibratory behavior using only two spatial dimensions. Thus, we propose an optical method of reconstructing the superior vocal fold surface in three spatial dimensions using a high-speed video camera and laser projection system. Using stereo-triangulation principles, we extend the camera-laser projector method and present an efficient image processing workflow to generate the three-dimensional vocal fold surfaces during phonation captured at 4000 frames per second. Initial results are provided for airflow-driven vibration of an ex vivo vocal fold model in which at least 75% of visible laser points contributed to the reconstructed surface. The method captures the vertical motion of the vocal folds at a high accuracy to allow for the computation of three-dimensional mucosal wave features such as vibratory amplitude, velocity, and asymmetry. PMID:26087485

Calibration procedure for a laser triangulation scanner with uncertainty evaluation

NASA Astrophysics Data System (ADS)

Genta, Gianfranco; Minetola, Paolo; Barbato, Giulio

2016-11-01

Most of low cost 3D scanning devices that are nowadays available on the market are sold without a user calibration procedure to correct measurement errors related to changes in environmental conditions. In addition, there is no specific international standard defining a procedure to check the performance of a 3D scanner along time. This paper aims at detailing a thorough methodology to calibrate a 3D scanner and assess its measurement uncertainty. The proposed procedure is based on the use of a reference ball plate and applied to a triangulation laser scanner. Experimental results show that the metrological performance of the instrument can be greatly improved by the application of the calibration procedure that corrects systematic errors and reduces the device's measurement uncertainty.

Mixed Methods, Triangulation, and Causal Explanation

ERIC Educational Resources Information Center

Howe, Kenneth R.

2012-01-01

This article distinguishes a disjunctive conception of mixed methods/triangulation, which brings different methods to bear on different questions, from a conjunctive conception, which brings different methods to bear on the same question. It then examines a more inclusive, holistic conception of mixed methods/triangulation that accommodates…

A laser-based vision system for weld quality inspection.

PubMed

Huang, Wei; Kovacevic, Radovan

2011-01-01

Welding is a very complex process in which the final weld quality can be affected by many process parameters. In order to inspect the weld quality and detect the presence of various weld defects, different methods and systems are studied and developed. In this paper, a laser-based vision system is developed for non-destructive weld quality inspection. The vision sensor is designed based on the principle of laser triangulation. By processing the images acquired from the vision sensor, the geometrical features of the weld can be obtained. Through the visual analysis of the acquired 3D profiles of the weld, the presences as well as the positions and sizes of the weld defects can be accurately identified and therefore, the non-destructive weld quality inspection can be achieved.

A Laser-Based Vision System for Weld Quality Inspection

PubMed Central

Huang, Wei; Kovacevic, Radovan

2011-01-01

Welding is a very complex process in which the final weld quality can be affected by many process parameters. In order to inspect the weld quality and detect the presence of various weld defects, different methods and systems are studied and developed. In this paper, a laser-based vision system is developed for non-destructive weld quality inspection. The vision sensor is designed based on the principle of laser triangulation. By processing the images acquired from the vision sensor, the geometrical features of the weld can be obtained. Through the visual analysis of the acquired 3D profiles of the weld, the presences as well as the positions and sizes of the weld defects can be accurately identified and therefore, the non-destructive weld quality inspection can be achieved. PMID:22344308

Measurement of vibration using phase only correlation technique

NASA Astrophysics Data System (ADS)

Balachandar, S.; Vipin, K.

2017-08-01

A novel method for the measurement of vibration is proposed and demonstrated. The proposed experiment is based on laser triangulation: consists of line laser, object under test and a high speed camera remotely controlled by a software. Experiment involves launching a line-laser probe beam perpendicular to the axis of the vibrating object. The reflected probe beam is recorded by a high speed camera. The dynamic position of the line laser in camera plane is governed by the magnitude and frequency of the vibrating test-object. Using phase correlation technique the maximum distance travelled by the probe beam in CCD plane is measured in terms of pixels using MATLAB. An actual displacement of the object in mm is measured by calibration. Using displacement data with time, other vibration associated quantities such as acceleration, velocity and frequency are evaluated. The preliminary result of the proposed method is reported for acceleration from 1g to 3g, and from frequency 6Hz to 26Hz. The results are closely matching with its theoretical values. The advantage of the proposed method is that it is a non-destructive method and using phase correlation algorithm subpixel displacement in CCD plane can be measured with high accuracy.

CW Laser radar for combustion diagnostics

NASA Astrophysics Data System (ADS)

Malmqvist, Elin; Brydegaard, Mikkel; Aldén, Marcus; Bood, Joakim

2018-04-01

A CW-laser radar system developed for combustion diagnostics is described. The system is based on triangulation to attain range information. A portable system has been constructed and here we show some result from measurements in various flames, for example Rayleigh scattering thermometry and monitoring of particle distributions with high temporal and spatial resolution. The concept can equally well be based on pulsed lasers, allowing suppression of background emission through gated detection.

Fast Optical Hazard Detection for Planetary Rovers Using Multiple Spot Laser Triangulation

NASA Technical Reports Server (NTRS)

Matthies, L.; Balch, T.; Wilcox, B.

1997-01-01

A new laser-based optical sensor system that provides hazard detection for planetary rovers is presented. It is anticipated that the sensor can support safe travel at speeds up to 6cm/second for large (1m) rovers in full sunlight on Earth or Mars. The system overcomes limitations in an older design that require image differencing ot detect a laser stripe in full sun.

Determination of the human spine curve based on laser triangulation.

PubMed

Poredoš, Primož; Čelan, Dušan; Možina, Janez; Jezeršek, Matija

2015-02-05

The main objective of the present method was to automatically obtain a spatial curve of the thoracic and lumbar spine based on a 3D shape measurement of a human torso with developed scoliosis. Manual determination of the spine curve, which was based on palpation of the thoracic and lumbar spinous processes, was found to be an appropriate way to validate the method. Therefore a new, noninvasive, optical 3D method for human torso evaluation in medical practice is introduced. Twenty-four patients with confirmed clinical diagnosis of scoliosis were scanned using a specially developed 3D laser profilometer. The measuring principle of the system is based on laser triangulation with one-laser-plane illumination. The measurement took approximately 10 seconds at 700 mm of the longitudinal translation along the back. The single point measurement accuracy was 0.1 mm. Computer analysis of the measured surface returned two 3D curves. The first curve was determined by manual marking (manual curve), and the second was determined by detecting surface curvature extremes (automatic curve). The manual and automatic curve comparison was given as the root mean square deviation (RMSD) for each patient. The intra-operator study involved assessing 20 successive measurements of the same person, and the inter-operator study involved assessing measurements from 8 operators. The results obtained for the 24 patients showed that the typical RMSD between the manual and automatic curve was 5.0 mm in the frontal plane and 1.0 mm in the sagittal plane, which is a good result compared with palpatory accuracy (9.8 mm). The intra-operator repeatability of the presented method in the frontal and sagittal planes was 0.45 mm and 0.06 mm, respectively. The inter-operator repeatability assessment shows that that the presented method is invariant to the operator of the computer program with the presented method. The main novelty of the presented paper is the development of a new, non-contact method that provides a quick, precise and non-invasive way to determine the spatial spine curve for patients with developed scoliosis and the validation of the presented method using the palpation of the spinous processes, where no harmful ionizing radiation is present.

Comparison of a novel surface laser scanning anthropometric technique to traditional methods for facial parameter measurements.

PubMed

Joe, Paula S; Ito, Yasushi; Shih, Alan M; Oestenstad, Riedar K; Lungu, Claudiu T

2012-01-01

This study was designed to determine if three-dimensional (3D) laser scanning techniques could be used to collect accurate anthropometric measurements, compared with traditional methods. The use of an alternative 3D method would allow for quick collection of data that could be used to change the parameters used for facepiece design, improving fit and protection for a wider variety of faces. In our study, 10 facial dimensions were collected using both the traditional calipers and tape method and a Konica-Minolta Vivid9i laser scanner. Scans were combined using RapidForm XOR software to create a single complete facial geometry of the subject as a triangulated surface with an associated texture image from which to obtain measurements. A paired t-test was performed on subject means in each measurement by method. Nine subjects were used in this study: five males (one African-American and four Caucasian females) and four females displaying a range of facial dimensions. Five measurements showed significant differences (p<0.05), with most accounted for by subject movements or amended by scanning technique modifications. Laser scanning measurements showed high precision and accuracy when compared with traditional methods. Significant differences found can be very small changes in measurements and are unlikely to present a practical difference. The laser scanning technique demonstrated reliable and quick anthropometric data collection for use in future projects in redesigning respirators.

Structured-Light Based 3d Laser Scanning of Semi-Submerged Structures

NASA Astrophysics Data System (ADS)

van der Lucht, J.; Bleier, M.; Leutert, F.; Schilling, K.; Nüchter, A.

2018-05-01

In this work we look at 3D acquisition of semi-submerged structures with a triangulation based underwater laser scanning system. The motivation is that we want to simultaneously capture data above and below water to create a consistent model without any gaps. The employed structured light scanner consist of a machine vision camera and a green line laser. In order to reconstruct precise surface models of the object it is necessary to model and correct for the refraction of the laser line and camera rays at the water-air boundary. We derive a geometric model for the refraction at the air-water interface and propose a method for correcting the scans. Furthermore, we show how the water surface is directly estimated from sensor data. The approach is verified using scans captured with an industrial manipulator to achieve reproducible scanner trajectories with different incident angles. We show that the proposed method is effective for refractive correction and that it can be applied directly to the raw sensor data without requiring any external markers or targets.

Tilt angle measurement with a Gaussian-shaped laser beam tracking

NASA Astrophysics Data System (ADS)

Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr; Lazar, Josef; Číp, Ondrej

2014-05-01

We have addressed the challenge to carry out the angular tilt stabilization of a laser guiding mirror which is intended to route a laser beam with a high energy density. Such an application requires good angular accuracy as well as large operating range, long term stability and absolute positioning. We have designed an instrument for such a high precision angular tilt measurement based on a triangulation method where a laser beam with Gaussian profile is reflected off the stabilized mirror and detected by an image sensor. As the angular deflection of the mirror causes a change of the beam spot position, the principal task is to measure the position on the image chip surface. We have employed a numerical analysis of the Gaussian intensity pattern which uses the nonlinear regression algorithm. The feasibility and performance of the method were tested by numeric modeling as well as experimentally. The experimental results indicate that the assembled instrument achieves a measurement error of 0.13 microradian in the range +/-0.65 degrees over the period of one hour. This corresponds to the dynamic range of 1:170 000.

Control electronics for a multi-laser/multi-detector scanning system

NASA Technical Reports Server (NTRS)

Kennedy, W.

1980-01-01

The Mars Rover Laser Scanning system uses a precision laser pointing mechanism, a photodetector array, and the concept of triangulation to perform three dimensional scene analysis. The system is used for real time terrain sensing and vision. The Multi-Laser/Multi-Detector laser scanning system is controlled by a digital device called the ML/MD controller. A next generation laser scanning system, based on the Level 2 controller, is microprocessor based. The new controller capabilities far exceed those of the ML/MD device. The first draft circuit details and general software structure are presented.

Measurement of shape and deformation of insect wing

NASA Astrophysics Data System (ADS)

Yin, Duo; Wei, Zhen; Wang, Zeyu; Zhou, Changqiu

2018-01-01

To measure the shape and deformation of an insect wing, a scanning setup adopting laser triangulation and image matching was developed. Only one industry camera with two light sources was employed to scan the transparent insect wings. 3D shape and point to point full field deformation of the wings could be obtained even when the wingspan is less than 3 mm. The venation and corrugation could be significantly identified from the results. The deformation of the wing under pin loading could be seen clearly from the results as well. Calibration shows that the shape and deformation measurement accuracies are no lower than 0.01 mm. Laser triangulation and image matching were combined dexterously to adapt wings' complex shape, size, and transparency. It is suitable for insect flight research or flapping wing micro-air vehicle development.

Triangulation, Respondent Validation, and Democratic Participation in Mixed Methods Research

ERIC Educational Resources Information Center

Torrance, Harry

2012-01-01

Over the past 10 years or so the "Field" of "Mixed Methods Research" (MMR) has increasingly been exerting itself as something separate, novel, and significant, with some advocates claiming paradigmatic status. Triangulation is an important component of mixed methods designs. Triangulation has its origins in attempts to validate research findings…

Optical profilometer using laser based conical triangulation for inspection of inner geometry of corroded pipes in cylindrical coordinates

NASA Astrophysics Data System (ADS)

Buschinelli, Pedro D. V.; Melo, João. Ricardo C.; Albertazzi, Armando; Santos, João. M. C.; Camerini, Claudio S.

2013-04-01

An axis-symmetrical optical laser triangulation system was developed by the authors to measure the inner geometry of long pipes used in the oil industry. It has a special optical configuration able to acquire shape information of the inner geometry of a section of a pipe from a single image frame. A collimated laser beam is pointed to the tip of a 45° conical mirror. The laser light is reflected in such a way that a radial light sheet is formed and intercepts the inner geometry and forms a bright laser line on a section of the inspected pipe. A camera acquires the image of the laser line through a wide angle lens. An odometer-based triggering system is used to shot the camera to acquire a set of equally spaced images at high speed while the device is moved along the pipe's axis. Image processing is done in real-time (between images acquisitions) thanks to the use of parallel computing technology. The measured geometry is analyzed to identify corrosion damages. The measured geometry and results are graphically presented using virtual reality techniques and devices as 3D glasses and head-mounted displays. The paper describes the measurement principles, calibration strategies, laboratory evaluation of the developed device, as well as, a practical example of a corroded pipe used in an industrial gas production plant.

Quantitative evaluation for small surface damage based on iterative difference and triangulation of 3D point cloud

NASA Astrophysics Data System (ADS)

Zhang, Yuyan; Guo, Quanli; Wang, Zhenchun; Yang, Degong

2018-03-01

This paper proposes a non-contact, non-destructive evaluation method for the surface damage of high-speed sliding electrical contact rails. The proposed method establishes a model of damage identification and calculation. A laser scanning system is built to obtain the 3D point cloud data of the rail surface. In order to extract the damage region of the rail surface, the 3D point cloud data are processed using iterative difference, nearest neighbours search and a data registration algorithm. The curvature of the point cloud data in the damage region is mapped to RGB color information, which can directly reflect the change trend of the curvature of the point cloud data in the damage region. The extracted damage region is divided into three prism elements by a method of triangulation. The volume and mass of a single element are calculated by the method of geometric segmentation. Finally, the total volume and mass of the damage region are obtained by the principle of superposition. The proposed method is applied to several typical injuries and the results are discussed. The experimental results show that the algorithm can identify damage shapes and calculate damage mass with milligram precision, which are useful for evaluating the damage in a further research stage.

Triangulation 2.0

ERIC Educational Resources Information Center

Denzin, Norman K.

2012-01-01

The author's thesis is simple and direct. Those in the mixed methods qualitative inquiry community need a new story line, one that does not confuse pragmatism for triangulation, and triangulation for mixed methods research (MMR). A different third way is required, one that inspires generative politics and dialogic democracy and helps shape…

High-Speed Laser Scanner Maps a Surface in Three Dimensions

NASA Technical Reports Server (NTRS)

Lavelle, Joseph; Schuet, Stefan

2006-01-01

A scanning optoelectronic instrument generates the digital equivalent of a threedimensional (X,Y,Z) map of a surface that spans an area with resolution on the order of 0.005 in. ( 0.125mm). Originally intended for characterizing surface flaws (e.g., pits) on space-shuttle thermal-insulation tiles, the instrument could just as well be used for similar purposes in other settings in which there are requirements to inspect the surfaces of many objects. While many commercial instruments can perform this surface-inspection function, the present instrument offers a unique combination of capabilities not available in commercial instruments. This instrument utilizes a laser triangulation method that has been described previously in NASA Tech Briefs in connection with simpler related instruments used for different purposes. The instrument includes a sensor head comprising a monochrome electronic camera and two lasers. The camera is a high-resolution

Laser Doppler position sensor for position and shape measurements of fast rotating objects

NASA Astrophysics Data System (ADS)

Czarske, Jürgen; Pfister, Thorsten; Büttner, Lars

2006-08-01

We report about a novel optical method based on laser Doppler velocimetry for position and shape measurements of moved solid state surfaces with approximately one micrometer position resolution. 3D shape measurements of a rotating cylinder inside a turning machine as well as tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm and 586 m/s blade tip velocity are presented. All results are in good agreement with conventional reference probes. The measurement accuracy of the laser Doppler position sensor is investigated in dependence of the speckle pattern. Furthermore, it is shown that this sensor offers high temporal resolution and high position resolution simultaneously and that shading can be reduced compared to triangulation. Consequently, the presented laser Doppler position sensor opens up new perspectives in the field of real-time manufacturing metrology and process control, for example controlling the turning and the grinding process or for future developments of turbo machines.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Zhiqi; He, Qing, E-mail: heqing@ise.neu.edu.cn; Xie, Zhi

For real-time and precise measurement of molten steel level in tundish during continuous casting, slag level and slag thickness are needed. Among which, the problem of slag thickness measurement has been solved in our previous work. In this paper, a systematic solution for slag level measurement based on laser triangulation is proposed. Being different from traditional laser triangulation, several aspects for measuring precision and robustness have been done. First, laser line is adopted for multi-position measurement to overcome the deficiency of single point laser range finder caused by the uneven surface of the slag. Second, the key parameters, such asmore » installing angle and minimum requirement of the laser power, are analyzed and determined based on the gray-body radiation theory to fulfill the rigorous requirement of measurement accuracy. Third, two kinds of severe noises in the acquired images, which are, respectively, caused by heat radiation and Electro-Magnetic Interference (EMI), are cleaned via morphological characteristic of the liquid slag and color difference between EMI and the laser signals, respectively. Fourth, as false target created by stationary slag usually disorders the measurement, valid signals of the slag are distinguished from the false ones to calculate the slag level. Then, molten steel level is obtained by the slag level minus the slag thickness. The measuring error of this solution is verified by the applications in steel plants, which is ±2.5 mm during steady casting and ±3.2 mm at the end of casting.« less

High-speed measurements of steel-plate deformations during laser surface processing.

PubMed

Jezersek, Matija; Gruden, Valter; Mozina, Janez

2004-10-04

In this paper we present a novel approach to monitoring the deformations of a steel plate's surface during various types of laser processing, e.g., engraving, marking, cutting, bending, and welding. The measuring system is based on a laser triangulation principle, where the laser projector generates multiple lines simultaneously. This enables us to measure the shape of the surface with a high sampling rate (80 Hz with our camera) and high accuracy (+/-7 microm). The measurements of steel-plate deformations for plates of different thickness and with different illumination patterns are presented graphically and in an animation.

Effective Data-Driven Calibration for a Galvanometric Laser Scanning System Using Binocular Stereo Vision.

PubMed

Tu, Junchao; Zhang, Liyan

2018-01-12

A new solution to the problem of galvanometric laser scanning (GLS) system calibration is presented. Under the machine learning framework, we build a single-hidden layer feedforward neural network (SLFN）to represent the GLS system, which takes the digital control signal at the drives of the GLS system as input and the space vector of the corresponding outgoing laser beam as output. The training data set is obtained with the aid of a moving mechanism and a binocular stereo system. The parameters of the SLFN are efficiently solved in a closed form by using extreme learning machine (ELM). By quantitatively analyzing the regression precision with respective to the number of hidden neurons in the SLFN, we demonstrate that the proper number of hidden neurons can be safely chosen from a broad interval to guarantee good generalization performance. Compared to the traditional model-driven calibration, the proposed calibration method does not need a complex modeling process and is more accurate and stable. As the output of the network is the space vectors of the outgoing laser beams, it costs much less training time and can provide a uniform solution to both laser projection and 3D-reconstruction, in contrast with the existing data-driven calibration method which only works for the laser triangulation problem. Calibration experiment, projection experiment and 3D reconstruction experiment are respectively conducted to test the proposed method, and good results are obtained.

Onomatopoeia characters extraction from comic images using constrained Delaunay triangulation

NASA Astrophysics Data System (ADS)

Liu, Xiangping; Shoji, Kenji; Mori, Hiroshi; Toyama, Fubito

2014-02-01

A method for extracting onomatopoeia characters from comic images was developed based on stroke width feature of characters, since they nearly have a constant stroke width in a number of cases. An image was segmented with a constrained Delaunay triangulation. Connected component grouping was performed based on the triangles generated by the constrained Delaunay triangulation. Stroke width calculation of the connected components was conducted based on the altitude of the triangles generated with the constrained Delaunay triangulation. The experimental results proved the effectiveness of the proposed method.

Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders — from Optical Triangulation to the Automotive Field

PubMed Central

Wu, Jih-Huah; Pen, Cheng-Chung; Jiang, Joe-Air

2008-01-01

With their significant features, the applications of complementary metal-oxide semiconductor (CMOS) image sensors covers a very extensive range, from industrial automation to traffic applications such as aiming systems, blind guidance, active/passive range finders, etc. In this paper CMOS image sensor-based active and passive range finders are presented. The measurement scheme of the proposed active/passive range finders is based on a simple triangulation method. The designed range finders chiefly consist of a CMOS image sensor and some light sources such as lasers or LEDs. The implementation cost of our range finders is quite low. Image processing software to adjust the exposure time (ET) of the CMOS image sensor to enhance the performance of triangulation-based range finders was also developed. An extensive series of experiments were conducted to evaluate the performance of the designed range finders. From the experimental results, the distance measurement resolutions achieved by the active range finder and the passive range finder can be better than 0.6% and 0.25% within the measurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests on applications of the developed CMOS image sensor-based range finders to the automotive field were also conducted. The experimental results demonstrated that our range finders are well-suited for distance measurements in this field. PMID:27879789

The Application of a Multiphase Triangulation Approach to Mixed Methods: The Research of an Aspiring School Principal Development Program

ERIC Educational Resources Information Center

Youngs, Howard; Piggot-Irvine, Eileen

2012-01-01

Mixed methods research has emerged as a credible alternative to unitary research approaches. The authors show how a combination of a triangulation convergence model with a triangulation multilevel model was used to research an aspiring school principal development pilot program. The multilevel model is used to show the national and regional levels…

A Rapid Method to Achieve Aero-Engine Blade Form Detection

PubMed Central

Sun, Bin; Li, Bing

2015-01-01

This paper proposes a rapid method to detect aero-engine blade form, according to the characteristics of an aero-engine blade surface. This method first deduces an inclination error model in free-form surface measurements based on the non-contact laser triangulation principle. Then a four-coordinate measuring system was independently developed, a special fixture was designed according to the blade shape features, and a fast measurement of the blade features path was planned. Finally, by using the inclination error model for correction of acquired data, the measurement error that was caused by tilt form is compensated. As a result the measurement accuracy of the Laser Displacement Sensor was less than 10 μm. After the experimental verification, this method makes full use of optical non-contact measurement fast speed, high precision and wide measuring range of features. Using a standard gauge block as a measurement reference, the coordinate system conversion data is simple and practical. It not only improves the measurement accuracy of the blade surface, but also its measurement efficiency. Therefore, this method increases the value of the measurement of complex surfaces. PMID:26039420

A rapid method to achieve aero-engine blade form detection.

PubMed

Sun, Bin; Li, Bing

2015-06-01

This paper proposes a rapid method to detect aero-engine blade form, according to the characteristics of an aero-engine blade surface. This method first deduces an inclination error model in free-form surface measurements based on the non-contact laser triangulation principle. Then a four-coordinate measuring system was independently developed, a special fixture was designed according to the blade shape features, and a fast measurement of the blade features path was planned. Finally, by using the inclination error model for correction of acquired data, the measurement error that was caused by tilt form is compensated. As a result the measurement accuracy of the Laser Displacement Sensor was less than 10 μm. After the experimental verification, this method makes full use of optical non-contact measurement fast speed, high precision and wide measuring range of features. Using a standard gauge block as a measurement reference, the coordinate system conversion data is simple and practical. It not only improves the measurement accuracy of the blade surface, but also its measurement efficiency. Therefore, this method increases the value of the measurement of complex surfaces.

Triangulation and the importance of establishing valid methods for food safety culture evaluation.

PubMed

Jespersen, Lone; Wallace, Carol A

2017-10-01

The research evaluates maturity of food safety culture in five multi-national food companies using method triangulation, specifically self-assessment scale, performance documents, and semi-structured interviews. Weaknesses associated with each individual method are known but there are few studies in food safety where a method triangulation approach is used for both data collection and data analysis. Significantly, this research shows that individual results taken in isolation can lead to wrong conclusions, resulting in potentially failing tactics and wasted investments. However, by applying method triangulation and reviewing results from a range of culture measurement tools it is possible to better direct investments and interventions. The findings add to the food safety culture paradigm beyond a single evaluation of food safety culture using generic culture surveys. Copyright © 2017. Published by Elsevier Ltd.

Study on Practical Technologies of Aerial Triangulation for Real Scene 3d Moeling with Oblique Photography

NASA Astrophysics Data System (ADS)

Cai, Z.; Liu, W.; Luo, G.; Xiang, Z.

2018-04-01

The key technologies in the real scene 3D modeling of oblique photography mainly include the data acquisition of oblique photography, layout and surveying of photo control points, oblique camera calibration, aerial triangulation, dense matching of multi-angle image, building of triangulation irregular network (TIN) and TIN simplification and automatic texture mapping, among which aerial triangulation is the core and the results of aerial triangulation directly affect the later model effect and the corresponding data accuracy. Starting from this point of view, this paper aims to study the practical technologies of aerial triangulation for real scene 3D modeling with oblique photography and finally proposes a technical method of aerial triangulation with oblique photography which can be put into practice.

Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture

PubMed Central

Bitelli, Gabriele; Simone, Andrea; Girardi, Fabrizio; Lantieri, Claudio

2012-01-01

The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey. PMID:23012535

Assessment of four midcarpal radiologic determinations.

PubMed

Cho, Mickey S; Battista, Vincent; Dubin, Norman H; Pirela-Cruz, Miguel

2006-03-01

Several radiologic measurement methods have been described for determining static carpal alignment of the wrist. These include the scapholunate, radiolunate, and capitolunate angles. The triangulation method is an alternative radiologic measurement which we believe is easier to use and more reproducible and reliable than the above mentioned methods. The purpose of this study is to assess the intraobserver reproducibility and interobserver reliability of the triangulation method, scapholunate, radiolunate, and capitolunate angles. Twenty orthopaedic residents and staff at varying levels of training made four radiologic measurements including the scapholunate, radiolunate and capitolunate angles as well as the triangulation method on five different lateral, digitized radiographs of the wrist and forearm in neutral radioulnar deviation. Thirty days after the initial measurements, the participants repeated the four radiologic measurements using the same radiographs. The triangulation method had the best intra-and-interobserver agreement of the four methods tested. This agreement was significantly better than the capitolunate and radiolunate angles. The scapholunate angle had the next best intraobserver reproducibility and interobserver reliability. The triangulation method has the best overall observer agreement when compared to the scapholunate, radiolunate, and capitolunate angles in determining static midcarpal alignment. No comment can be made on the validity of the measurements since there is no radiographic gold standard in determining static carpal alignment.

A novel weld seam detection method for space weld seam of narrow butt joint in laser welding

NASA Astrophysics Data System (ADS)

Shao, Wen Jun; Huang, Yu; Zhang, Yong

2018-02-01

Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.

A Triangulation Method for Identifying Hydrostratigraphic Locations of Well Screens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whiteside, T. S.

2015-01-31

A method to identify the hydrostratigraphic location of well screens was developed using triangulation with known locations. This method was applied to all of the monitor wells being used to develop the new GSA groundwater model. Results from this method are closely aligned with those from an alternate method which uses a mesh surface.

A Mixed Methods Approach to Understanding School Counseling Program Evaluation: High School Counselors' Methods and Perceptions

ERIC Educational Resources Information Center

Aucoin, Jennifer Mangrum

2013-01-01

The purpose of this mixed methods concurrent triangulation study was to examine the program evaluation practices of high school counselors. A total of 294 high school counselors in Texas were assessed using a mixed methods concurrent triangulation design. A researcher-developed survey, the School Counseling Program Evaluation Questionnaire…

The Use of Triangulation Methods in Qualitative Educational Research

ERIC Educational Resources Information Center

Oliver-Hoyo, Maria; Allen, DeeDee

2006-01-01

Triangulation involves the careful reviewing of data collected through different methods in order to achieve a more accurate and valid estimate of qualitative results for a particular construct. This paper describes how we used three qualitative methods of data collection to study attitudes of students toward graphing, hands-on activities, and…

Constrained CVT meshes and a comparison of triangular mesh generators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Hoa; Burkardt, John; Gunzburger, Max

2009-01-01

Mesh generation in regions in Euclidean space is a central task in computational science, and especially for commonly used numerical methods for the solution of partial differential equations, e.g., finite element and finite volume methods. We focus on the uniform Delaunay triangulation of planar regions and, in particular, on how one selects the positions of the vertices of the triangulation. We discuss a recently developed method, based on the centroidal Voronoi tessellation (CVT) concept, for effecting such triangulations and present two algorithms, including one new one, for CVT-based grid generation. We also compare several methods, including CVT-based methods, for triangulatingmore » planar domains. To this end, we define several quantitative measures of the quality of uniform grids. We then generate triangulations of several planar regions, including some having complexities that are representative of what one may encounter in practice. We subject the resulting grids to visual and quantitative comparisons and conclude that all the methods considered produce high-quality uniform grids and that the CVT-based grids are at least as good as any of the others.« less

Development of an optical three-dimensional laser tracker using dual modulated laser diodes and a signal detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hau-Wei; Chen, Chieh-Li; Liu, Chien-Hung

Laser trackers are widely used in industry for tasks such as the assembly of airplanes and automobiles, contour measurement, and robot calibration. However, laser trackers are expensive, and the corresponding solution procedure is very complex. The influence of measurement uncertainties is also significant. This study proposes a three-dimensional space position measurement system which consists of two tracking modules, a zero tracking angle return subsystem, and a target quadrant photodiode (QPD). The target QPD is placed on the object being tracked. The origin locking method is used to keep the rays on the origin of the target QPD. The position ofmore » the target QPD is determined using triangulation since the two laser rays are projected onto one QPD. Modulation and demodulation are utilized to separate the coupled positional values. The experiment results show that measurement errors in the X, Y, and Z directions are less than {+-}0.05% when the measured object was moved by 300, 300, and 200 mm in the X, Y, and Z axes, respectively. The theoretical measurement error estimated from the measurement model is between {+-}0.02% and {+-}0.07% within the defined measurable range. The proposed system can be applied to the measurements of machine tools and robot arms.« less

Development of an optical three-dimensional laser tracker using dual modulated laser diodes and a signal detector.

PubMed

Lee, Hau-Wei; Chen, Chieh-Li; Liu, Chien-Hung

2011-03-01

Laser trackers are widely used in industry for tasks such as the assembly of airplanes and automobiles, contour measurement, and robot calibration. However, laser trackers are expensive, and the corresponding solution procedure is very complex. The influence of measurement uncertainties is also significant. This study proposes a three-dimensional space position measurement system which consists of two tracking modules, a zero tracking angle return subsystem, and a target quadrant photodiode (QPD). The target QPD is placed on the object being tracked. The origin locking method is used to keep the rays on the origin of the target QPD. The position of the target QPD is determined using triangulation since the two laser rays are projected onto one QPD. Modulation and demodulation are utilized to separate the coupled positional values. The experiment results show that measurement errors in the X, Y, and Z directions are less than ±0.05% when the measured object was moved by 300, 300, and 200 mm in the X, Y, and Z axes, respectively. The theoretical measurement error estimated from the measurement model is between ±0.02% and ±0.07% within the defined measurable range. The proposed system can be applied to the measurements of machine tools and robot arms.

Development of an optical three-dimensional laser tracker using dual modulated laser diodes and a signal detector

NASA Astrophysics Data System (ADS)

Lee, Hau-Wei; Chen, Chieh-Li; Liu, Chien-Hung

2011-03-01

Laser trackers are widely used in industry for tasks such as the assembly of airplanes and automobiles, contour measurement, and robot calibration. However, laser trackers are expensive, and the corresponding solution procedure is very complex. The influence of measurement uncertainties is also significant. This study proposes a three-dimensional space position measurement system which consists of two tracking modules, a zero tracking angle return subsystem, and a target quadrant photodiode (QPD). The target QPD is placed on the object being tracked. The origin locking method is used to keep the rays on the origin of the target QPD. The position of the target QPD is determined using triangulation since the two laser rays are projected onto one QPD. Modulation and demodulation are utilized to separate the coupled positional values. The experiment results show that measurement errors in the X, Y, and Z directions are less than ±0.05% when the measured object was moved by 300, 300, and 200 mm in the X, Y, and Z axes, respectively. The theoretical measurement error estimated from the measurement model is between ±0.02% and ±0.07% within the defined measurable range. The proposed system can be applied to the measurements of machine tools and robot arms.

Adjustment technique without explicit formation of normal equations /conjugate gradient method/

NASA Technical Reports Server (NTRS)

Saxena, N. K.

1974-01-01

For a simultaneous adjustment of a large geodetic triangulation system, a semiiterative technique is modified and used successfully. In this semiiterative technique, known as the conjugate gradient (CG) method, original observation equations are used, and thus the explicit formation of normal equations is avoided, 'huge' computer storage space being saved in the case of triangulation systems. This method is suitable even for very poorly conditioned systems where solution is obtained only after more iterations. A detailed study of the CG method for its application to large geodetic triangulation systems was done that also considered constraint equations with observation equations. It was programmed and tested on systems as small as two unknowns and three equations up to those as large as 804 unknowns and 1397 equations. When real data (573 unknowns, 965 equations) from a 1858-km-long triangulation system were used, a solution vector accurate to four decimal places was obtained in 2.96 min after 1171 iterations (i.e., 2.0 times the number of unknowns).

Application of a Line Laser Scanner for Bed Form Tracking in a Laboratory Flume

NASA Astrophysics Data System (ADS)

de Ruijsscher, T. V.; Hoitink, A. J. F.; Dinnissen, S.; Vermeulen, B.; Hazenberg, P.

2018-03-01

A new measurement method for continuous detection of bed forms in movable bed laboratory experiments is presented and tested. The device consists of a line laser coupled to a 3-D camera, which makes use of triangulation. This allows to measure bed forms during morphodynamic experiments, without removing the water from the flume. A correction is applied for the effect of laser refraction at the air-water interface. We conclude that the absolute measurement error increases with increasing flow velocity, its standard deviation increases with water depth and flow velocity, and the percentage of missing values increases with water depth. Although 71% of the data is lost in a pilot moving bed experiment with sand, still high agreement between flowing water and dry bed measurements is found when a robust LOcally weighted regrESSion (LOESS) procedure is applied. This is promising for bed form tracking applications in laboratory experiments, especially when lightweight sediments like polystyrene are used, which require smaller flow velocities to achieve dynamic similarity to the prototype. This is confirmed in a moving bed experiment with polystyrene.

Assessing the Potential Use of Eye-Tracking Triangulation for Evaluating the Usability of an Online Diabetes Exercise System.

PubMed

Schaarup, Clara; Hartvigsen, Gunnar; Larsen, Lars Bo; Tan, Zheng-Hua; Årsand, Eirik; Hejlesen, Ole Kristian

2015-01-01

The Online Diabetes Exercise System was developed to motivate people with Type 2 diabetes to do a 25 minutes low-volume high-intensity interval training program. In a previous multi-method evaluation of the system, several usability issues were identified and corrected. Despite the thorough testing, it was unclear whether all usability problems had been identified using the multi-method evaluation. Our hypothesis was that adding the eye-tracking triangulation to the multi-method evaluation would increase the accuracy and completeness when testing the usability of the system. The study design was an Eye-tracking Triangulation; conventional eye-tracking with predefined tasks followed by The Post-Experience Eye-Tracked Protocol (PEEP). Six Areas of Interests were the basis for the PEEP-session. The eye-tracking triangulation gave objective and subjective results, which are believed to be highly relevant for designing, implementing, evaluating and optimizing systems in the field of health informatics. Future work should include testing the method on a larger and more representative group of users and apply the method on different system types.

Triangulation and Mixed Methods Designs: Data Integration with New Research Technologies

ERIC Educational Resources Information Center

Fielding, Nigel G.

2012-01-01

Data integration is a crucial element in mixed methods analysis and conceptualization. It has three principal purposes: illustration, convergent validation (triangulation), and the development of analytic density or "richness." This article discusses such applications in relation to new technologies for social research, looking at three…

Research on Visualization of Ground Laser Radar Data Based on Osg

NASA Astrophysics Data System (ADS)

Huang, H.; Hu, C.; Zhang, F.; Xue, H.

2018-04-01

Three-dimensional (3D) laser scanning is a new advanced technology integrating light, machine, electricity, and computer technologies. It can conduct 3D scanning to the whole shape and form of space objects with high precision. With this technology, you can directly collect the point cloud data of a ground object and create the structure of it for rendering. People use excellent 3D rendering engine to optimize and display the 3D model in order to meet the higher requirements of real time realism rendering and the complexity of the scene. OpenSceneGraph (OSG) is an open source 3D graphics engine. Compared with the current mainstream 3D rendering engine, OSG is practical, economical, and easy to expand. Therefore, OSG is widely used in the fields of virtual simulation, virtual reality, science and engineering visualization. In this paper, a dynamic and interactive ground LiDAR data visualization platform is constructed based on the OSG and the cross-platform C++ application development framework Qt. In view of the point cloud data of .txt format and the triangulation network data file of .obj format, the functions of 3D laser point cloud and triangulation network data display are realized. It is proved by experiments that the platform is of strong practical value as it is easy to operate and provides good interaction.

Yet another method for triangulation and contouring for automated cartography

NASA Technical Reports Server (NTRS)

De Floriani, L.; Falcidieno, B.; Nasy, G.; Pienovi, C.

1982-01-01

An algorithm is presented for hierarchical subdivision of a set of three-dimensional surface observations. The data structure used for obtaining the desired triangulation is also singularly appropriate for extracting contours. Some examples are presented, and the results obtained are compared with those given by Delaunay triangulation. The data points selected by the algorithm provide a better approximation to the desired surface than do randomly selected points.

An object-oriented framework for distributed hydrologic and geomorphic modeling using triangulated irregular networks

NASA Astrophysics Data System (ADS)

Tucker, Gregory E.; Lancaster, Stephen T.; Gasparini, Nicole M.; Bras, Rafael L.; Rybarczyk, Scott M.

2001-10-01

We describe a new set of data structures and algorithms for dynamic terrain modeling using a triangulated irregular network (TINs). The framework provides an efficient method for storing, accessing, and updating a Delaunay triangulation and its associated Voronoi diagram. The basic data structure consists of three interconnected data objects: triangles, nodes, and directed edges. Encapsulating each of these geometric elements within a data object makes it possible to essentially decouple the TIN representation from the modeling applications that make use of it. Both the triangulation and its corresponding Voronoi diagram can be rapidly retrieved or updated, making these methods well suited to adaptive remeshing schemes. We develop a set of algorithms for defining drainage networks and identifying closed depressions (e.g., lakes) for hydrologic and geomorphic modeling applications. We also outline simple numerical algorithms for solving network routing and 2D transport equations within the TIN framework. The methods are illustrated with two example applications, a landscape evolution model and a distributed rainfall-runoff model.

Spectrum of the Laplace-Beltrami operator and the phase structure of causal dynamical triangulations

NASA Astrophysics Data System (ADS)

Clemente, Giuseppe; D'Elia, Massimo

2018-06-01

We propose a new method to characterize the different phases observed in the nonperturbative numerical approach to quantum gravity known as causal dynamical triangulations. The method is based on the analysis of the eigenvalues and the eigenvectors of the Laplace-Beltrami operator computed on the triangulations: it generalizes previous works based on the analysis of diffusive processes and proves capable of providing more detailed information on the geometric properties of the triangulations. In particular, we apply the method to the analysis of spatial slices, showing that the different phases can be characterized by a new order parameter related to the presence or absence of a gap in the spectrum of the Laplace-Beltrami operator, and deriving an effective dimensionality of the slices at the different scales. We also propose quantities derived from the spectrum that could be used to monitor the running to the continuum limit around a suitable critical point in the phase diagram, if any is found.

An advancing front Delaunay triangulation algorithm designed for robustness

NASA Technical Reports Server (NTRS)

Mavriplis, D. J.

1992-01-01

A new algorithm is described for generating an unstructured mesh about an arbitrary two-dimensional configuration. Mesh points are generated automatically by the algorithm in a manner which ensures a smooth variation of elements, and the resulting triangulation constitutes the Delaunay triangulation of these points. The algorithm combines the mathematical elegance and efficiency of Delaunay triangulation algorithms with the desirable point placement features, boundary integrity, and robustness traditionally associated with advancing-front-type mesh generation strategies. The method offers increased robustness over previous algorithms in that it cannot fail regardless of the initial boundary point distribution and the prescribed cell size distribution throughout the flow-field.

Thickness and topographic inspection of RPG contact lenses by optical triangulation

NASA Astrophysics Data System (ADS)

Costa, Manuel F. M.

2001-06-01

Optical triangulation as a non-destructive test method extensively proved its usefulness on the dimensional and topographic inspection of a large range of objects and surfaces. In this communication the issue of microtopographic and thickness inspection of hard contact lenses (RPG) is addressed. The use of optical triangulation is discussed based on the results of the application of our MICROTOP.03.MFC microtopographer to this kind of tasks will be presented.

Triangulation Error Analysis for the Barium Ion Cloud Experiment. M.S. Thesis - North Carolina State Univ.

NASA Technical Reports Server (NTRS)

Long, S. A. T.

1973-01-01

The triangulation method developed specifically for the Barium Ion Cloud Project is discussed. Expression for the four displacement errors, the three slope errors, and the curvature error in the triangulation solution due to a probable error in the lines-of-sight from the observation stations to points on the cloud are derived. The triangulation method is then used to determine the effect of the following on these different errors in the solution: the number and location of the stations, the observation duration, east-west cloud drift, the number of input data points, and the addition of extra cameras to one of the stations. The pointing displacement errors, and the pointing slope errors are compared. The displacement errors in the solution due to a probable error in the position of a moving station plus the weighting factors for the data from the moving station are also determined.

Feminist Approaches to Triangulation: Uncovering Subjugated Knowledge and Fostering Social Change in Mixed Methods Research

ERIC Educational Resources Information Center

Hesse-Biber, Sharlene

2012-01-01

This article explores the deployment of triangulation in the service of uncovering subjugated knowledge and promoting social change for women and other oppressed groups. Feminist approaches to mixed methods praxis create a tight link between the research problem and the research design. An analysis of selected case studies of feminist praxis…

A method for rapid measurement of laser ablation rate of hard dental tissue

NASA Astrophysics Data System (ADS)

Perhavec, T.; Gorkič, A.; Bračun, D.; Diaci, J.

2009-06-01

The aim of the study reported here is the development of a new method which allows rapid and accurate in-vitro measurements of three-dimensional (3D) shape of laser ablated craters in hard dental tissues and the determination of crater volume, ablation rate and speed. The method is based on the optical triangulation principle. A laser sheet projector illuminates the surface of a tooth, mounted on a linear translation stage. As the tooth is moved by the translation stage a fast digital video camera captures series of images of the illuminated surface. The images are analyzed to determine a 3D model of the surface. Custom software is employed to analyze the 3D model and to determine the volume of the ablated craters. Key characteristics of the method are discussed as well as some practical aspects pertinent to its use. The method has been employed in an in-vitro study to examine the ablation rates and speeds of the two main laser types currently employed in dentistry, Er:YAG and Er,Cr:YSGG. Ten samples of extracted human molar teeth were irradiated with laser pulse energies from 80 mJ to the maximum available energy (970 mJ with the Er:YAG, and 260 mJ with the Er,Cr:YSGG). About 2000 images of each ablated tooth surface have been acquired along a translation range of 10 mm, taking about 10 s and providing close to 1 million surface measurement points. Volumes of 170 ablated craters (half of them in dentine and the other half in enamel) were determined from this data and used to examine the ablated volume per pulse energy and ablation speed. The results show that, under the same conditions, the ablated volume per pulse energy achieved by the Er:YAG laser exceeds that of the Er,Cr:YSGG laser in almost all regimes for dentine and enamel. The maximum Er:YAG laser ablation speeds (1.2 mm 3/s in dentine and 0.7 mm 3/s in enamel) exceed those obtained by the Er,Cr:YSGG laser (0.39 mm 3/s in dentine and 0.12 mm 3/s in enamel). Since the presented method proves to be easy to use and allows quite rapid measurements it may become a valuable tool to study the influence of various laser parameters on the outcome of laser ablation of dental tissues.

Methodological triangulation: an approach to understanding data.

PubMed

Bekhet, Abir K; Zauszniewski, Jaclene A

2012-01-01

To describe the use of methodological triangulation in a study of how people who had moved to retirement communities were adjusting. Methodological triangulation involves using more than one kind of method to study a phenomenon. It has been found to be beneficial in providing confirmation of findings, more comprehensive data, increased validity and enhanced understanding of studied phenomena. While many researchers have used this well-established technique, there are few published examples of its use. The authors used methodological triangulation in their study of people who had moved to retirement communities in Ohio, US. A blended qualitative and quantitative approach was used. The collected qualitative data complemented and clarified the quantitative findings by helping to identify common themes. Qualitative data also helped in understanding interventions for promoting 'pulling' factors and for overcoming 'pushing' factors of participants. The authors used focused research questions to reflect the research's purpose and four evaluative criteria--'truth value', 'applicability', 'consistency' and 'neutrality'--to ensure rigour. This paper provides an example of how methodological triangulation can be used in nursing research. It identifies challenges associated with methodological triangulation, recommends strategies for overcoming them, provides a rationale for using triangulation and explains how to maintain rigour. Methodological triangulation can be used to enhance the analysis and the interpretation of findings. As data are drawn from multiple sources, it broadens the researcher's insight into the different issues underlying the phenomena being studied.

Academic Rigour, Managerial Relevance and Triangulation of Research Methods: A Perspective of Expectations Fulfilment in Postgraduate Education

ERIC Educational Resources Information Center

Hui, Loi Teck; Fatt, Quek Kia

2008-01-01

Developing high-quality human capital and advancing existing knowledge stocks are crucial for the competitive advantage of a nation. The authors argue that offering postgraduate programmes that give great emphasis to academic rigour, managerial relevance and the triangulation of research methods is vital if these ends are to be achieved. They…

The accuracy of the CAD system using intraoral and extraoral scanners for designing of fixed dental prostheses.

PubMed

Shimizu, Sakura; Shinya, Akikazu; Kuroda, Soichi; Gomi, Harunori

2017-07-26

The accuracy of prostheses affects clinical success and is, in turn, affected by the accuracy of the scanner and CAD programs. Thus, their accuracy is important. The first aim of this study was to evaluate the accuracy of an intraoral scanner with active triangulation (Cerec Omnicam), an intraoral scanner with a confocal laser (3Shape Trios), and an extraoral scanner with active triangulation (D810). The second aim of this study was to compare the accuracy of the digital crowns designed with two different scanner/CAD combinations. The accuracy of the intraoral scanners and extraoral scanner was clinically acceptable. Marginal and internal fit of the digital crowns fabricated using the intraoral scanner and CAD programs were inferior to those fabricated using the extraoral scanner and CAD programs.

Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders - from Optical Triangulation to the Automotive Field.

PubMed

Wu, Jih-Huah; Pen, Cheng-Chung; Jiang, Joe-Air

2008-03-13

With their significant features, the applications of complementary metal-oxidesemiconductor (CMOS) image sensors covers a very extensive range, from industrialautomation to traffic applications such as aiming systems, blind guidance, active/passiverange finders, etc. In this paper CMOS image sensor-based active and passive rangefinders are presented. The measurement scheme of the proposed active/passive rangefinders is based on a simple triangulation method. The designed range finders chieflyconsist of a CMOS image sensor and some light sources such as lasers or LEDs. Theimplementation cost of our range finders is quite low. Image processing software to adjustthe exposure time (ET) of the CMOS image sensor to enhance the performance oftriangulation-based range finders was also developed. An extensive series of experimentswere conducted to evaluate the performance of the designed range finders. From theexperimental results, the distance measurement resolutions achieved by the active rangefinder and the passive range finder can be better than 0.6% and 0.25% within themeasurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests onapplications of the developed CMOS image sensor-based range finders to the automotivefield were also conducted. The experimental results demonstrated that our range finders arewell-suited for distance measurements in this field.

3D digitization methods based on laser excitation and active triangulation: a comparison

NASA Astrophysics Data System (ADS)

Aubreton, Olivier; Mériaudeau, Fabrice; Truchetet, Frédéric

2016-04-01

3D reconstruction of surfaces is an important topic in computer vision and corresponds to a large field of applications: industrial inspection, reverse engineering, object recognition, biometry, archeology… Because of the large varieties of applications, one can find in the literature a lot of approaches which can be classified into two families: passive and active [1]. Certainly because of their reliability, active approaches, using imaging system with an additional controlled light source, seem to be the most commonly used in the industrial field. In this domain, the 3D digitization approach based on active 3D triangulation has had important developments during the last ten years [2] and seems to be mature today if considering the important number of systems proposed by manufacturers. Unfortunately, the performances of active 3D scanners depend on the optical properties of the surface to digitize. As an example, on Fig 1.a, a 3D shape with a diffuse surface has been digitized with Comet V scanner (Steinbichler). The 3D reconstruction is presented on Fig 1.b. The same experiment was carried out on a similar object (same shape) but presenting a specular surface (Fig 1.c and Fig 1.d) ; it can clearly be observed, that the specularity influences of the performance of the digitization.

Comparative analysis of hierarchical triangulated irregular networks to represent 3D elevation in terrain databases

NASA Astrophysics Data System (ADS)

Abdelguerfi, Mahdi; Wynne, Chris; Cooper, Edgar; Ladner, Roy V.; Shaw, Kevin B.

1997-08-01

Three-dimensional terrain representation plays an important role in a number of terrain database applications. Hierarchical triangulated irregular networks (TINs) provide a variable-resolution terrain representation that is based on a nested triangulation of the terrain. This paper compares and analyzes existing hierarchical triangulation techniques. The comparative analysis takes into account how aesthetically appealing and accurate the resulting terrain representation is. Parameters, such as adjacency, slivers, and streaks, are used to provide a measure on how aesthetically appealing the terrain representation is. Slivers occur when the triangulation produces thin and slivery triangles. Streaks appear when there are too many triangulations done at a given vertex. Simple mathematical expressions are derived for these parameters, thereby providing a fairer and a more easily duplicated comparison. In addition to meeting the adjacency requirement, an aesthetically pleasant hierarchical TINs generation algorithm is expected to reduce both slivers and streaks while maintaining accuracy. A comparative analysis of a number of existing approaches shows that a variant of a method originally proposed by Scarlatos exhibits better overall performance.

Qualitative to quantitative: linked trajectory of method triangulation in a study on HIV/AIDS in Goa, India.

PubMed

Bailey, Ajay; Hutter, Inge

2008-10-01

With 3.1 million people estimated to be living with HIV/AIDS in India and 39.5 million people globally, the epidemic has posed academics the challenge of identifying behaviours and their underlying beliefs in the effort to reduce the risk of HIV transmission. The Health Belief Model (HBM) is frequently used to identify risk behaviours and adherence behaviour in the field of HIV/AIDS. Risk behaviour studies that apply HBM have been largely quantitative and use of qualitative methodology is rare. The marriage of qualitative and quantitative methods has never been easy. The challenge is in triangulating the methods. Method triangulation has been largely used to combine insights from the qualitative and quantitative methods but not to link both the methods. In this paper we suggest a linked trajectory of method triangulation (LTMT). The linked trajectory aims to first gather individual level information through in-depth interviews and then to present the information as vignettes in focus group discussions. We thus validate information obtained from in-depth interviews and gather emic concepts that arise from the interaction. We thus capture both the interpretation and the interaction angles of the qualitative method. Further, using the qualitative information gained, a survey is designed. In doing so, the survey questions are grounded and contextualized. We employed this linked trajectory of method triangulation in a study on the risk assessment of HIV/AIDS among migrant and mobile men. Fieldwork was carried out in Goa, India. Data come from two waves of studies, first an explorative qualitative study (2003), second a larger study (2004-2005), including in-depth interviews (25), focus group discussions (21) and a survey (n=1259). By employing the qualitative to quantitative LTMT we can not only contextualize the existing concepts of the HBM, but also validate new concepts and identify new risk groups.

Reconstructing the Sky Location of Gravitational-Wave Detected Compact Binary Systems: Methodology for Testing and Comparison

NASA Technical Reports Server (NTRS)

Sidney, T.; Aylott, B.; Christensen, N.; Farr, B.; Farr, W.; Feroz, F.; Gair, J.; Grover, K.; Graff, P.; Hanna, C.;

Reconstructing the sky location of gravitational-wave detected compact binary systems: Methodology for testing and comparison

NASA Astrophysics Data System (ADS)

Sidery, T.; Aylott, B.; Christensen, N.; Farr, B.; Farr, W.; Feroz, F.; Gair, J.; Grover, K.; Graff, P.; Hanna, C.; Kalogera, V.; Mandel, I.; O'Shaughnessy, R.; Pitkin, M.; Price, L.; Raymond, V.; Röver, C.; Singer, L.; van der Sluys, M.; Smith, R. J. E.; Vecchio, A.; Veitch, J.; Vitale, S.

2014-04-01

The problem of reconstructing the sky position of compact binary coalescences detected via gravitational waves is a central one for future observations with the ground-based network of gravitational-wave laser interferometers, such as Advanced LIGO and Advanced Virgo. Different techniques for sky localization have been independently developed. They can be divided in two broad categories: fully coherent Bayesian techniques, which are high latency and aimed at in-depth studies of all the parameters of a source, including sky position, and "triangulation-based" techniques, which exploit the data products from the search stage of the analysis to provide an almost real-time approximation of the posterior probability density function of the sky location of a detection candidate. These techniques have previously been applied to data collected during the last science runs of gravitational-wave detectors operating in the so-called initial configuration. Here, we develop and analyze methods for assessing the self consistency of parameter estimation methods and carrying out fair comparisons between different algorithms, addressing issues of efficiency and optimality. These methods are general, and can be applied to parameter estimation problems other than sky localization. We apply these methods to two existing sky localization techniques representing the two above-mentioned categories, using a set of simulated inspiral-only signals from compact binary systems with a total mass of ≤20M⊙ and nonspinning components. We compare the relative advantages and costs of the two techniques and show that sky location uncertainties are on average a factor ≈20 smaller for fully coherent techniques than for the specific variant of the triangulation-based technique used during the last science runs, at the expense of a factor ≈1000 longer processing time.

Methods for acquiring data on terrain geomorphology, course geometry and kinematics of competitors' runs in alpine skiing: a historical review.

PubMed

Erdmann, Włodzimierz S; Giovanis, Vassilis; Aschenbrenner, Piotr; Kiriakis, Vaios; Suchanowski, Andrzej

2017-01-01

This paper aims at the description and comparison of methods of topographic analysis of racing courses at all disciplines of alpine skiing sports for the purposes of obtaining: terrain geomorphology (snowless and with snow), course geometry, and competitors' runs. The review presents specific methods and instruments according to the order of their historical appearance as follows: (1) azimuth method with the use of a compass, tape and goniometer instruments; (2) optical method with geodetic theodolite, laser and photocells; (3) triangulation method with the aid of a tape and goniometer; (4) image method with the use of video cameras; (5) differential global positioning system and carrier phase global positioning system methods. Described methods were used at homologation procedure, at training sessions, during competitions of local level and during International Ski Federation World Championships or World Cups. Some methods were used together. In order to provide detailed data on course setting and skiers' running it is recommended to analyse course geometry and kinematics data of competitors' running for all important competitions.

Interpretation of laser/multi-sensor data for short range terrain modeling and hazard detection

NASA Technical Reports Server (NTRS)

Messing, B. S.

1980-01-01

A terrain modeling algorithm that would reconstruct the sensed ground images formed by the triangulation scheme, and classify as unsafe any terrain feature that would pose a hazard to a roving vehicle is described. This modeler greatly reduces quantization errors inherent in a laser/sensing system through the use of a thinning algorithm. Dual filters are employed to separate terrain steps from the general landscape, simplifying the analysis of terrain features. A crosspath analysis is utilized to detect and avoid obstacles that would adversely affect the roll of the vehicle. Computer simulations of the rover on various terrains examine the performance of the modeler.

Design of noise barrier inspection system for high-speed railway

NASA Astrophysics Data System (ADS)

Liu, Bingqian; Shao, Shuangyun; Feng, Qibo; Ma, Le; Cholryong, Kim

2016-10-01

The damage of noise barriers will highly reduce the transportation safety of the high-speed railway. In this paper, an online inspection system of noise barrier based on laser vision for the safety of high-speed railway is proposed. The inspection system, mainly consisted of a fast camera and a line laser, installed in the first carriage of the high-speed CIT(Composited Inspection Train).A Laser line was projected on the surface of the noise barriers and the images of the light line were received by the camera while the train is running at high speed. The distance between the inspection system and the noise barrier can be obtained based on laser triangulation principle. The results of field tests show that the proposed system can meet the need of high speed and high accuracy to get the contour distortion of the noise barriers.

Triangulation-based edge measurement using polyview optics

NASA Astrophysics Data System (ADS)

Li, Yinan; Kästner, Markus; Reithmeier, Eduard

2018-04-01

Laser triangulation sensors as non-contact measurement devices are widely used in industry and research for profile measurements and quantitative inspections. Some technical applications e.g. edge measurements usually require a configuration of a single sensor and a translation stage or a configuration of multiple sensors, so that they can measure a large measurement range that is out of the scope of a single sensor. However, the cost of both configurations is high, due to the additional rotational axis or additional sensor. This paper provides a special measurement system for measurement of great curved surfaces based on a single sensor configuration. Utilizing a self-designed polyview optics and calibration process, the proposed measurement system allows an over 180° FOV (field of view) with a precise measurement accuracy as well as an advantage of low cost. The detailed capability of this measurement system based on experimental data is discussed in this paper.

Technical Survey and Evaluation of Underwater Sensors and Remotely Operated Vehicles

DTIC Science & Technology

1993-05-01

differentiates these systems from the multitude of towed instrument packages. Construction of the vehicle is either open metallic framework or closed...3-29. AN APPLICATION OF LASERS AND TRIANGULATION TO MEASURING THE DISTANCE FROM THE CAMERA TO A TARGET (Tusting, 1990) I9 differential range...of ultraviolet light at 260 nm. Using ultraviolet light to detect the carbon-hydrogen stretch allows TOM to differentiate aromatics from other

Interprofessional collaboration from nurses and physicians – A triangulation of quantitative and qualitative data

PubMed

Schärli, Marianne; Müller, Rita; Martin, Jacqueline S; Spichiger, Elisabeth; Spirig, Rebecca

2017-01-01

Background: Interprofessional collaboration between nurses and physicians is a recurrent challenge in daily clinical practice. To ameliorate the situation, quantitative or qualitative studies are conducted. However, the results of these studies have often been limited by the methods chosen. Aim: To describe the synthesis of interprofessional collaboration from the nursing perspective by triangulating quantitative and qualitative data. Method: Data triangulation was performed as a sub-project of the interprofessional Sinergia DRG Research program. Initially, quantitative and qualitative data were analyzed separately in a mixed methods design. By means of triangulation a „meta-matrix“ resulted in a four-step process. Results: The „meta-matrix“ displays all relevant quantitative and qualitative results as well as their interrelations on one page. Relevance, influencing factors as well as consequences of interprofessional collaboration for patients, relatives and systems become visible. Conclusion: For the first time, the interprofessional collaboration from the nursing perspective at five Swiss hospitals is shown in a „meta-matrix“. The consequences of insufficient collaboration between nurses and physicians are considerable. This is why it’s necessary to invest in interprofessional concepts. In the „meta-matrix“ the factors which influence the interprofessional collaboration positively or negatively are visible.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Qishi; Berry, M. L..; Grieme, M.

We propose a localization-based radiation source detection (RSD) algorithm using the Ratio of Squared Distance (ROSD) method. Compared with the triangulation-based method, the advantages of this ROSD method are multi-fold: i) source location estimates based on four detectors improve their accuracy, ii) ROSD provides closed-form source location estimates and thus eliminates the imaginary-roots issue, and iii) ROSD produces a unique source location estimate as opposed to two real roots (if any) in triangulation, and obviates the need to identify real phantom roots during clustering.

A novel near real-time laser scanning device for geometrical determination of pleural cavity surface.

PubMed

Kim, Michele M; Zhu, Timothy C

2013-02-02

During HPPH-mediated pleural photodynamic therapy (PDT), it is critical to determine the anatomic geometry of the pleural surface quickly as there may be movement during treatment resulting in changes with the cavity. We have developed a laser scanning device for this purpose, which has the potential to obtain the surface geometry in real-time. A red diode laser with a holographic template to create a pattern and a camera with auto-focusing abilities are used to scan the cavity. In conjunction with a calibration with a known surface, we can use methods of triangulation to reconstruct the surface. Using a chest phantom, we are able to obtain a 360 degree scan of the interior in under 1 minute. The chest phantom scan was compared to an existing CT scan to determine its accuracy. The laser-camera separation can be determined through the calibration with 2mm accuracy. The device is best suited for environments that are on the scale of a chest cavity (between 10cm and 40cm). This technique has the potential to produce cavity geometry in real-time during treatment. This would enable PDT treatment dosage to be determined with greater accuracy. Works are ongoing to build a miniaturized device that moves the light source and camera via a fiber-optics bundle commonly used for endoscopy with increased accuracy.

Simultaneous Intrinsic and Extrinsic Parameter Identification of a Hand-Mounted Laser-Vision Sensor

PubMed Central

Lee, Jong Kwang; Kim, Kiho; Lee, Yongseok; Jeong, Taikyeong

2011-01-01

In this paper, we propose a simultaneous intrinsic and extrinsic parameter identification of a hand-mounted laser-vision sensor (HMLVS). A laser-vision sensor (LVS), consisting of a camera and a laser stripe projector, is used as a sensor component of the robotic measurement system, and it measures the range data with respect to the robot base frame using the robot forward kinematics and the optical triangulation principle. For the optimal estimation of the model parameters, we applied two optimization techniques: a nonlinear least square optimizer and a particle swarm optimizer. Best-fit parameters, including both the intrinsic and extrinsic parameters of the HMLVS, are simultaneously obtained based on the least-squares criterion. From the simulation and experimental results, it is shown that the parameter identification problem considered was characterized by a highly multimodal landscape; thus, the global optimization technique such as a particle swarm optimization can be a promising tool to identify the model parameters for a HMLVS, while the nonlinear least square optimizer often failed to find an optimal solution even when the initial candidate solutions were selected close to the true optimum. The proposed optimization method does not require good initial guesses of the system parameters to converge at a very stable solution and it could be applied to a kinematically dissimilar robot system without loss of generality. PMID:22164104

Three-dimensional unstructured grid refinement and optimization using edge-swapping

NASA Technical Reports Server (NTRS)

Gandhi, Amar; Barth, Timothy

1993-01-01

This paper presents a three-dimensional (3-D) 'edge-swapping method based on local transformations. This method extends Lawson's edge-swapping algorithm into 3-D. The 3-D edge-swapping algorithm is employed for the purpose of refining and optimizing unstructured meshes according to arbitrary mesh-quality measures. Several criteria including Delaunay triangulations are examined. Extensions from two to three dimensions of several known properties of Delaunay triangulations are also discussed.

Surface acquisition through virtual milling

NASA Technical Reports Server (NTRS)

Merriam, Marshal L.

1993-01-01

Surface acquisition deals with the reconstruction of three dimensional objects from a set of data points. The most straightforward techniques require human intervention, a time consuming proposition. It is desirable to develop a fully automated alternative. Such a method is proposed in this paper. It makes use of surface measurements obtained from a 3-D laser digitizer - an instrument which provides the (x,y,z) coordinates of surface data points from various viewpoints. These points are assembled into several partial surfaces using a visibility constraint and a 2-D triangulation technique. Reconstruction of the final object requires merging these partial surfaces. This is accomplished through a procedure that emulates milling, a standard machining operation. From a geometrical standpoint the problem reduces to constructing the intersection of two or more non-convex polyhedra.

Quality Tetrahedral Mesh Smoothing via Boundary-Optimized Delaunay Triangulation

PubMed Central

Gao, Zhanheng; Yu, Zeyun; Holst, Michael

2012-01-01

Despite its great success in improving the quality of a tetrahedral mesh, the original optimal Delaunay triangulation (ODT) is designed to move only inner vertices and thus cannot handle input meshes containing “bad” triangles on boundaries. In the current work, we present an integrated approach called boundary-optimized Delaunay triangulation (B-ODT) to smooth (improve) a tetrahedral mesh. In our method, both inner and boundary vertices are repositioned by analytically minimizing the error between a paraboloid function and its piecewise linear interpolation over the neighborhood of each vertex. In addition to the guaranteed volume-preserving property, the proposed algorithm can be readily adapted to preserve sharp features in the original mesh. A number of experiments are included to demonstrate the performance of our method. PMID:23144522

Study on real-time elevator brake failure predictive system

NASA Astrophysics Data System (ADS)

Guo, Jun; Fan, Jinwei

2013-10-01

This paper presented a real-time failure predictive system of the elevator brake. Through inspecting the running state of the coil by a high precision long range laser triangulation non-contact measurement sensor, the displacement curve of the coil is gathered without interfering the original system. By analyzing the displacement data using the diagnostic algorithm, the hidden danger of the brake system can be discovered in time and thus avoid the according accident.

X-ray diagnostics of hohlraum plasma flow

NASA Astrophysics Data System (ADS)

Back, C. A.; Glenzer, S. H.; Landen, O. L.; MacGowan, B. J.; Shepard, T. D.

1997-01-01

In this study we use spectroscopy and x-ray imaging to investigate the macroscopic plasma flow in mm-sized laser-produced hohlraum plasmas. By using multiple diagnostics to triangulate the emission on a single experiment, we can pinpoint the position of dopants placed inside the hohlraum. X-ray emission from the foil has been used in the past to measure electron temperature. Here we analyze the spatial movement of dopant plasmas for comparison to hydrodynamic calculations.

A Laser-Based Measuring System for Online Quality Control of Car Engine Block.

PubMed

Li, Xing-Qiang; Wang, Zhong; Fu, Lu-Hua

2016-11-08

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and measured surface is too small to require manual operation. This lowers the measuring efficiency and becomes an obstacle to perform automatic measurement. In this article, a high-speed, automatic measuring system is proposed to take the place of pneumatic devices by using a laser-based measuring unit. The measuring unit is considered as a set of several measuring modules, where each of them acts like a single bore gauge and is made of four laser triangulation sensors (LTSs), which are installed on different positions and in opposite directions. The spatial relationship among these LTSs was calibrated before measurements. Sampling points from measured shaft holes can be collected by the measuring unit. A unified mathematical model was established for both calibration and measurement. Based on the established model, the relative pose between the measuring unit and measured workpiece does not impact the measuring accuracy. This frees the measuring unit from accurate positioning or adjustment, and makes it possible to realize fast and automatic measurement. The proposed system and method were finally validated by experiments.

Laser spectroscopy for totally non-intrusive detection of oxygen in modified atmosphere food packages

NASA Astrophysics Data System (ADS)

Cocola, L.; Fedel, M.; Poletto, L.; Tondello, G.

2015-04-01

A device for measuring the oxygen concentration inside packages in modified atmosphere working in a completely non-intrusive way has been developed and tested. The device uses tunable diode laser spectroscopy in a geometry similar to a short distance LIDAR: A laser beam is sent through the top film of a food package, and the absorption is measured by detecting the light scattered by the bottom of the container or by a portion of the food herein contained. The device can operate completely in a contactless way from the package, and the distances of absorption both outside and inside the package are measured with a triangulation system. The performances of the device have been tested for various types of containers, and absolute values for the oxygen concentration have been compared with standard albeit destructive measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rebay, S.

This work is devoted to the description of an efficient unstructured mesh generation method entirely based on the Delaunay triangulation. The distinctive characteristic of the proposed method is that point positions and connections are computed simultaneously. This result is achieved by taking advantage of the sequential way in which the Bowyer-Watson algorithm computes the Delaunay triangulation. Two methods are proposed which have great geometrical flexibility, in that they allow us to treat domains of arbitrary shape and topology and to generate arbitrarily nonuniform meshes. The methods are computationally efficient and are applicable both in two and three dimensions. 11 refs.,more » 20 figs., 1 tab.« less

A Program to Improve the Triangulated Surface Mesh Quality Along Aircraft Component Intersections

NASA Technical Reports Server (NTRS)

Cliff, Susan E.

2005-01-01

A computer program has been developed for improving the quality of unstructured triangulated surface meshes in the vicinity of component intersections. The method relies solely on point removal and edge swapping for improving the triangulations. It can be applied to any lifting surface component such as a wing, canard or horizontal tail component intersected with a fuselage, or it can be applied to a pylon that is intersected with a wing, fuselage or nacelle. The lifting surfaces or pylon are assumed to be aligned in the axial direction with closed trailing edges. The method currently maintains salient edges only at leading and trailing edges of the wing or pylon component. This method should work well for any shape of fuselage that is free of salient edges at the intersection. The method has been successfully demonstrated on a total of 125 different test cases that include both blunt and sharp wing leading edges. The code is targeted for use in the automated environment of numerical optimization where geometric perturbations to individual components can be critical to the aerodynamic performance of a vehicle. Histograms of triangle aspect ratios are reported to assess the quality of the triangles attached to the intersection curves before and after application of the program. Large improvements to the quality of the triangulations were obtained for the 125 test cases; the quality was sufficient for use with an automated tetrahedral mesh generation program that is used as part of an aerodynamic shape optimization method.

Triangulation methods for automated docking

NASA Technical Reports Server (NTRS)

Bales, John W.

1996-01-01

An automated docking system must have a reliable method for determining range and orientation of the passive (target) vehicle with respect to the active vehicle. This method must also provide accurate information on the rates of change of range to and orientation of the passive vehicle. The method must be accurate within required tolerances and capable of operating in real time. The method being developed at Marshall Space Flight Center employs a single TV camera, a laser illumination system and a target consisting, in its minimal configuration, of three retro-reflectors. Two of the retro-reflectors are mounted flush to the same surface, with the third retro-reflector mounted to a post fixed midway between the other two and jutting at a right angle from the surface. For redundancy, two additional retroreflectors are mounted on the surface on a line at right angles to the line containing the first two retro-reflectors, and equally spaced on either side of the post. The target vehicle will contain a large target for initial acquisition and several smaller targets for close range.

Neural networks for the generation of sea bed models using airborne lidar bathymetry data

NASA Astrophysics Data System (ADS)

Kogut, Tomasz; Niemeyer, Joachim; Bujakiewicz, Aleksandra

2016-06-01

Various sectors of the economy such as transport and renewable energy have shown great interest in sea bed models. The required measurements are usually carried out by ship-based echo sounding, but this method is quite expensive. A relatively new alternative is data obtained by airborne lidar bathymetry. This study investigates the accuracy of these data, which was obtained in the context of the project `Investigation on the use of airborne laser bathymetry in hydrographic surveying'. A comparison to multi-beam echo sounding data shows only small differences in the depths values of the data sets. The IHO requirements of the total horizontal and vertical uncertainty for laser data are met. The second goal of this paper is to compare three spatial interpolation methods, namely Inverse Distance Weighting (IDW), Delaunay Triangulation (TIN), and supervised Artificial Neural Networks (ANN), for the generation of sea bed models. The focus of our investigation is on the amount of required sampling points. This is analyzed by manually reducing the data sets. We found that the three techniques have a similar performance almost independently of the amount of sampling data in our test area. However, ANN are more stable when using a very small subset of points.

A Feedforward Control Approach to the Local Navigation Problem for Autonomous Vehicles

DTIC Science & Technology

1994-05-02

AD-A282 787 " A Feedforward Control Approach to the Local Navigation Problem for Autonomous Vehicles Alonzo Kelly CMU-RI-TR-94-17 The Robotics...follow, or a direction to prefer, it cannot generate its own strategic goals. Therefore, it solves the local planning problem for autonomous vehicles . The... autonomous vehicles . It is intelligent because it uses range images that are generated from either a laser rangefinder or a stereo triangulation

Three-dimensional dynamic deformation monitoring using a laser-scanning system

NASA Astrophysics Data System (ADS)

Al-Hanbali, Nedal N.; Teskey, William F.

1994-10-01

Non-contact dynamic deformation monitoring (e.g. with a laser scanning system) is very useful in monitoring changes in alignment and changes in size and shape of coupled operating machines. If relative movements between coupled operating machines are large, excessive wear in the machines or unplanned shutdowns due to machinery failure will occur. The purpose of non-contact dynamic deformation monitoring is to identify the causes of large movements and point to remedial action that can be taken to prevent them. The laser scanning system is a laser-based 3D vision system. The system-technique is based on an auto- synchronized triangulation scanning scheme. The system provides accurate, fast, and reliable 3D measurements and can measure objects between 0.5 m to 100 m with a field of view of 40 degree(s) X 50 degree(s). The system is flexible in terms of providing control over the scanned area and depth. The system also provides the user with the intensity image in addition to the depth coded image. This paper reports on the preliminary testing of this system to monitor surface movements and target (point) movements. The monitoring resolution achieved for an operating motorized alignment test rig in the lab was 1 mm for surface movements and 0.50 m for target movements. Raw data manipulation, local calibration, and the method of relating measurements to control points will be discussed. Possibilities for improving the resolution and recommendations for future development will also be presented.

Non-Contact Measurement Using A Laser Scanning Probe

NASA Astrophysics Data System (ADS)

Modjarrad, Amir

1989-03-01

Traditional high accuracy touch-trigger probing can now be complemented by high speed, non-contact, profile scanning to give another "dimension" to the three-dimensional Co-ordinate Measuring Machines (CMMs). Some of the features of a specially developed laser scanning probe together with the trade-offs involved in the design of inspection systems that use triangulation are examined. Applications of such a laser probe on CMMs are numerous since high speed scanning allows inspection of many different components and surfaces. For example, car body panels, tyre moulds, aircraft wing skins, turbine blades, wax and clay models, plastics, etc. Other applications include in-process surveillance in manufacturing and food processing, robotics vision and many others. Some of these applications are discussed and practical examples, case studies and experimental results are given with particular reference to use on CMMs. In conclusion, future developments and market trends in high speed non-contact measurement are discussed.

Location accuracy evaluation of lightning location systems using natural lightning flashes recorded by a network of high-speed cameras

NASA Astrophysics Data System (ADS)

Alves, J.; Saraiva, A. C. V.; Campos, L. Z. D. S.; Pinto, O., Jr.; Antunes, L.

2014-12-01

This work presents a method for the evaluation of location accuracy of all Lightning Location System (LLS) in operation in southeastern Brazil, using natural cloud-to-ground (CG) lightning flashes. This can be done through a multiple high-speed cameras network (RAMMER network) installed in the Paraiba Valley region - SP - Brazil. The RAMMER network (Automated Multi-camera Network for Monitoring and Study of Lightning) is composed by four high-speed cameras operating at 2,500 frames per second. Three stationary black-and-white (B&W) cameras were situated in the cities of São José dos Campos and Caçapava. A fourth color camera was mobile (installed in a car), but operated in a fixed location during the observation period, within the city of São José dos Campos. The average distance among cameras was 13 kilometers. Each RAMMER sensor position was determined so that the network can observe the same lightning flash from different angles and all recorded videos were GPS (Global Position System) time stamped, allowing comparisons of events between cameras and the LLS. The RAMMER sensor is basically composed by a computer, a Phantom high-speed camera version 9.1 and a GPS unit. The lightning cases analyzed in the present work were observed by at least two cameras, their position was visually triangulated and the results compared with BrasilDAT network, during the summer seasons of 2011/2012 and 2012/2013. The visual triangulation method is presented in details. The calibration procedure showed an accuracy of 9 meters between the accurate GPS position of the object triangulated and the result from the visual triangulation method. Lightning return stroke positions, estimated with the visual triangulation method, were compared with LLS locations. Differences between solutions were not greater than 1.8 km.

Sparse reconstruction localization of multiple acoustic emissions in large diameter pipelines

NASA Astrophysics Data System (ADS)

Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

2017-04-01

A sparse reconstruction localization method is proposed, which is capable of localizing multiple acoustic emission events occurring closely in time. The events may be due to a number of sources, such as the growth of corrosion patches or cracks. Such acoustic emissions may yield localization failure if a triangulation method is used. The proposed method is implemented both theoretically and experimentally on large diameter thin-walled pipes. Experimental examples are presented, which demonstrate the failure of a triangulation method when multiple sources are present in this structure, while highlighting the capabilities of the proposed method. The examples are generated from experimental data of simulated acoustic emission events. The data corresponds to helical guided ultrasonic waves generated in a 3 m long large diameter pipe by pencil lead breaks on its outer surface. Acoustic emission waveforms are recorded by six sparsely distributed low-profile piezoelectric transducers instrumented on the outer surface of the pipe. The same array of transducers is used for both the proposed and the triangulation method. It is demonstrated that the proposed method is able to localize multiple events occurring closely in time. Furthermore, the matching pursuit algorithm and the basis pursuit densoising approach are each evaluated as potential numerical tools in the proposed sparse reconstruction method.

Kinetic and dynamic Delaunay tetrahedralizations in three dimensions

NASA Astrophysics Data System (ADS)

Schaller, Gernot; Meyer-Hermann, Michael

2004-09-01

We describe algorithms to implement fully dynamic and kinetic three-dimensional unconstrained Delaunay triangulations, where the time evolution of the triangulation is not only governed by moving vertices but also by a changing number of vertices. We use three-dimensional simplex flip algorithms, a stochastic visibility walk algorithm for point location and in addition, we propose a new simple method of deleting vertices from an existing three-dimensional Delaunay triangulation while maintaining the Delaunay property. As an example, we analyse the performance in various cases of practical relevance. The dual Dirichlet tessellation can be used to solve differential equations on an irregular grid, to define partitions in cell tissue simulations, for collision detection etc.

Precision Timing and Measurement for Inference with Laser and Vision

DTIC Science & Technology

2010-01-01

Robotics 24, 8-9 (2007), 699–722. [84] Nüchter, A., Surmann, H., Lingemann, K., and Hertzberg, J. Semantic scene analysis of scanned 3D indoor...Delaunay based triangulation can be ob- tained. Popping the points back to their 3D locations yields a feature sensitive surface mesh . Sequeira et al... texture maps acquired from cameras, the eye can be fooled into believing that the mesh quality is better than it really is. Range images are used to

A Laser-Based Measuring System for Online Quality Control of Car Engine Block

PubMed Central

Li, Xing-Qiang; Wang, Zhong; Fu, Lu-Hua

2016-01-01

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and measured surface is too small to require manual operation. This lowers the measuring efficiency and becomes an obstacle to perform automatic measurement. In this article, a high-speed, automatic measuring system is proposed to take the place of pneumatic devices by using a laser-based measuring unit. The measuring unit is considered as a set of several measuring modules, where each of them acts like a single bore gauge and is made of four laser triangulation sensors (LTSs), which are installed on different positions and in opposite directions. The spatial relationship among these LTSs was calibrated before measurements. Sampling points from measured shaft holes can be collected by the measuring unit. A unified mathematical model was established for both calibration and measurement. Based on the established model, the relative pose between the measuring unit and measured workpiece does not impact the measuring accuracy. This frees the measuring unit from accurate positioning or adjustment, and makes it possible to realize fast and automatic measurement. The proposed system and method were finally validated by experiments. PMID:27834839

Metrological characterization of 3D imaging devices

NASA Astrophysics Data System (ADS)

Guidi, G.

2013-04-01

Manufacturers often express the performance of a 3D imaging device in various non-uniform ways for the lack of internationally recognized standard requirements for metrological parameters able to identify the capability of capturing a real scene. For this reason several national and international organizations in the last ten years have been developing protocols for verifying such performance. Ranging from VDI/VDE 2634, published by the Association of German Engineers and oriented to the world of mechanical 3D measurements (triangulation-based devices), to the ASTM technical committee E57, working also on laser systems based on direct range detection (TOF, Phase Shift, FM-CW, flash LADAR), this paper shows the state of the art about the characterization of active range devices, with special emphasis on measurement uncertainty, accuracy and resolution. Most of these protocols are based on special objects whose shape and size are certified with a known level of accuracy. By capturing the 3D shape of such objects with a range device, a comparison between the measured points and the theoretical shape they should represent is possible. The actual deviations can be directly analyzed or some derived parameters can be obtained (e.g. angles between planes, distances between barycenters of spheres rigidly connected, frequency domain parameters, etc.). This paper shows theoretical aspects and experimental results of some novel characterization methods applied to different categories of active 3D imaging devices based on both principles of triangulation and direct range detection.

Dental scanning in CAD/CAM technologies: laser beams

NASA Astrophysics Data System (ADS)

Sinescu, Cosmin; Negrutiu, Meda; Faur, Nicolae; Negru, Radu; Romînu, Mihai; Cozarov, Dalibor

2008-02-01

Scanning, also called digitizing, is the process of gathering the requisite data from an object. Many different technologies are used to collect three dimensional data. They range from mechanical and very slow, to radiation-based and highly-automated. Each technology has its advantages and disadvantages, and their applications and specifications overlap. The aims of this study are represented by establishing a viable method of digitally representing artifacts of dental casts, proposing a suitable scanner and post-processing software and obtaining 3D Models for the dental applications. The method is represented by the scanning procedure made by different scanners as the implicated materials. Scanners are the medium of data capture. 3D scanners aim to measure and record the relative distance between the object's surface and a known point in space. This geometric data is represented in the form of point cloud data. The contact and no contact scanners were presented. The results show that contact scanning procedures uses a touch probe to record the relative position of points on the objects' surface. This procedure is commonly used in Reverse engineering applications. Its merits are represented by efficiency for objects with low geometric surface detail. Disadvantages are represented by time consuming, this procedure being impractical for artifacts digitization. The non contact scanning procedure implies laser scanning (laser triangulation technology) and photogrammetry. As a conclusion it can be drawn that different types of dental structure needs different types of scanning procedures in order to obtain a competitive complex 3D virtual model that can be used in CAD/CAM technologies.

Epic Dimensions: a Comparative Analysis of 3d Acquisition Methods

NASA Astrophysics Data System (ADS)

Graham, C. A.; Akoglu, K. G.; Lassen, A. W.; Simon, S.

2017-08-01

When it comes to capturing the geometry of a cultural heritage artifact, there is certainly no dearth of possible acquisition techniques. As technology has rapidly developed, the availability of intuitive 3D generating tools has increased exponentially and made it possible even for non-specialists to create many models quickly. Though the by-products of these different acquisition methods may be incongruent in terms of quality, these discrepancies are not problematic, as there are many applications of 3D models, each with their own set of requirements. Comparisons of high-resolution 3D models of an iconic Babylonian tablet, captured via four different closerange technologies discussed in this paper assess which methods of 3D digitization best suit specific intended purposes related to research, conservation and education. Taking into consideration repeatability, time and resource implications, qualitative and quantitative potential and ease of use, this paper presents a study of the strengths and weakness of structured light scanning, triangulation laser scanning, photometric stereo and close-range photogrammetry, in the context of interactive investigation, conditions monitoring, engagement, and dissemination.

The Detection of Transport Land-Use Data Using Crowdsourcing Taxi Trajectory

NASA Astrophysics Data System (ADS)

Ai, T.; Yang, W.

2016-06-01

This study tries to explore the question of transport land-use change detection by large volume of vehicle trajectory data, presenting a method based on Deluanay triangulation. The whole method includes three steps. The first one is to pre-process the vehicle trajectory data including the point anomaly removing and the conversion of trajectory point to track line. Secondly, construct Deluanay triangulation within the vehicle trajectory line to detect neighborhood relation. Considering the case that some of the trajectory segments are too long, we use a interpolation measure to add more points for the improved triangulation. Thirdly, extract the transport road by cutting short triangle edge and organizing the polygon topology. We have conducted the experiment of transport land-use change discovery using the data of taxi track in Beijing City. We extract not only the transport land-use area but also the semantic information such as the transformation speed, the traffic jam distribution, the main vehicle movement direction and others. Compared with the existed transport network data, such as OpenStreet Map, our method is proved to be quick and accurate.

Procedures for the interpretation and use of elevation scanning laser/multi-sensor data for short range hazard detection and avoidance for an autonomous planetary rover

NASA Technical Reports Server (NTRS)

Troiani, N.; Yerazunis, S. W.

1978-01-01

An autonomous roving science vehicle that relies on terrain data acquired by a hierarchy of sensors for navigation was one method of carrying out such a mission. The hierarchy of sensors included a short range sensor with sufficient resolution to detect every possible obstacle and with the ability to make fast and reliable terrain characterizations. A multilaser, multidetector triangulation system was proposed as a short range sensor. The general system was studied to determine its perception capabilities and limitations. A specific rover and low resolution sensor system was then considered. After studying the data obtained, a hazard detection algorithm was developed that accounts for all possible terrains given the sensor resolution. Computer simulation of the rover on various terrains was used to test the entire hazard detection system.

A Triangulation Methodology in Research on Social Cultures.

ERIC Educational Resources Information Center

Owens, Robert G.; And Others

The purpose of this research was to develop, test, and demonstrate a systematic methodology of triangulation. Triangulation is a technique used to establish credibility of data gathered in qualitative ways. Triangulated conclusions are more stable than any of the individual vantage points from which they were triangulated. Using a previous study…

Laser profilometer module based on a low-temperature cofired ceramic substrate

NASA Astrophysics Data System (ADS)

Heikkinen, Veli; Heikkinen, Mikko; Keranen, Kimmo; Mitikka, Risto S.; Putila, Veli-Pekka; Tukkiniemi, Kari

2005-09-01

We realized a laser profilometer module using low temperature cofired ceramics technology. The device consists of a vertical-cavity surface-emitting laser as the light source and a complementary metal oxide semiconductor image sensor as the detector. The laser transmitter produces a thin light stripe on the measurable object, and the receiver calculates the distance profile using triangulation. Because the design of optoelectronic modules, such as the laser profilometer, is usually carried out using specialized software, its electronic compatibility is very important. We developed a data transmission network using commercial optical, electrical, and mechanical design software, which enabled us to electronically transfer data between the designers. The module electronics were realized with multilayer ceramics technology that eases component assembly by providing precision alignment features in the substrate. The housing was manufactured from aluminum using electronic data transfer from the mechanical design software to the five-axis milling workstation. Target distance profiles were obtained from 100 points with an accuracy varying from 0.1 mm at a 5-cm distance to 2 cm at 1.5 m. The module has potential for distance measurement in portable devices where small size, light weight, and low power consumption are important.

Triangulation of multistation camera data to locate a curved line in space

NASA Technical Reports Server (NTRS)

Fricke, C. L.

1974-01-01

A method is described for finding the location of a curved line in space from local azimuth as a function of elevation data obtained at several observation sites. A least-squares criterion is used to insure the best fit to the data. The method is applicable to the triangulation of an object having no identifiable structural features, provided its width is very small compared with its length so as to approximate a line in space. The method was implemented with a digital computer program and was successfully applied to data obtained from photographs of a barium ion cloud which traced out the earth's magnetic field line at very high altitudes.

Passive range estimation using dual baseline triangulation

NASA Astrophysics Data System (ADS)

Pieper, Ronald J.; Cooper, Alfred W.; Pelegris, G.

1996-03-01

Modern combat systems based on active radar sensing suffer disadvantages against low-flying targets in cluttered backgrounds. Use of passive infrared sensors with these systems, either in cooperation or as an alternative, shows potential for improving target detection and declaration range for targets crossing the horizon. Realization of this potential requires fusion of target position data from dissimilar sensors, or passive sensor measurement of target range. The availability of passive sensors that can supply both range and bearing data on such targets would significantly extend the robustness of an integrated ship self-defense system. This paper considers a new method of range determination with passive sensors based on the principle of triangulation, extending the principle to two orthogonal baselines. The performance of single or double baseline triangulation depends on sensor bearing precision and direction to target. An expression for maximum triangulation range at a required accuracy is derived as a function of polar angle relative to the center of the dual-baseline system. Limitations in the dual- baseline model due to the geometrically assessed horizon are also considered.

Angles-Only Navigation: Position and Velocity Solution from Absolute Triangulation

DTIC Science & Technology

2011-01-01

geocentric position vectors. Using two vectors derived from each such observation (see next section), a solution for a portion of the boat’s track was...t)x0 describes the curvature of the path in the direction x 0, which, for a geocentric coordinate system and /(t) < 0, will be toward the center of...finite distances, with geocentric coordinates known to a meter or better (readily available on the Internet) a straightfor- ward triangulation method

Combining ESPI with laser scanning for 3D characterization of racing tyres sections

NASA Astrophysics Data System (ADS)

Pagliarulo, Vito; Farroni, Flavio; Ferraro, Pietro; Lanzotti, Antonio; Martorelli, Massimo; Memmolo, Pasquale; Speranza, Domenico; Timpone, Francesco

2018-05-01

In this work is exploited the possibility to use two optical techniques and combining their measurements for the 3D characterization of different tyres with particular attention to the tyre's section. Electronic Speckle Pattern Interferometry (ESPI) and Laser Scanner (LS) based on principle of triangulation have been employed for investigating and studying the tyre's section and 3D shape respectively. As case studies two different racing tyres, Michelin S9H and Pirelli Diablo respectively, have been considered. The investigation has been focused at the aim to evaluate and measure the section's components in order to add to the 3D model obtained by Laser Scanning accurate information about the different layers along through the tyres sections. It is important to note that the assessment about the different layers along the section is a very difficult task to obtain by visual inspection or classical microscopy and even with the LS. Here we demonstrate that the different layers can be easily highlighted and identified by mean of the ESPI.

Application of laser-based profilometry to tubing in power generating utilities

NASA Astrophysics Data System (ADS)

Doyle, James L.

1995-05-01

Over the past several years lasers have been employed in an ever widening number of applications in an incredibly diverse set of markets. In the area of nondestructive testing, however, laser-based systems have only recently made inroads into the commercial markets. About ten years ago QUEST Integrated, Inc., began working with the U.S. Navy to adapt the principal of laser triangulation to solve a serious maintenance related problem. The internal surfaces of marine boiler tubes were experiencing pitting and corrosion which had resulted in catastrophic shipboard failures. At that time, conventional visual methods only allowed operators to inspect the first eighteen inches of the tube using a rigid borescope. If any pits were located, a mechanical stylus mechanism was used to obtain an approximate depth measurement of the pit. The condition of the balance of the tube was then extrapolated based on this extremely limited amount of information. Often the worst pitting was found in the bends of the tube, which could not be inspected by the visual method. Finally, a catastrophic boiler failure on an aircraft carrier resulted in the initiation of a search by the U.S. Navy for a better solution. Quest was contracted to develop an articulated probe which could negotiate the full length of a boiler tube with multiple bends, and generate a complete digital map of the inside surface. A key requirement of this probe would be rapid and quantitative measurement of internal features such as ID pits and corrosion. In 1987 QUEST delivered the first laser- optic tube inspection system to the U.S. Navy for use in marine boiler tubes. The Laser Optic Tube Inspection System (LOTISTM) was immediately put to use and paid for itself many times over in reduced maintenance costs. Over the next six years several generations of LOTIS were developed for the U.S. Navy, each one providing more capabilities, improved inspection speeds, and more user friendly operator interface. Today, LOTIS is used for routine inspections on marine boiler tubes by the U.S. Navy, with units located in several parts of the United States and overseas. In 1993 QUEST began exploring the possibility of extending this technology to the inspection of commercial tubes used in power generation and chemical processing. The following is an overview of the use of laser profilometry for nondestructive testing.

A portable intra-oral scanner based on sinusoidal pattern of fast phase-shifting

NASA Astrophysics Data System (ADS)

Jan, Chia-Ming; Lin, Ying-Chieh

2016-03-01

This paper presented our current research about the intra-oral scanner made by MIRDC. Utilizing the sinusoidal pattern for fast phase-shifting technique to deal with 3D digitalization of human dental surface profile, the development of pseudo-phase shifting digital projection can easily achieve one type of full-field scanning instead of the common technique of the laser line scanning. Based on traditional Moiré method, we adopt projecting fringes and retrieve phase reconstruction to forward phase unwrapping. The phase difference between the plane and object can be exactly calculated from the desired fringe images, and the surface profile of object was probably reconstructed by using the phase differences information directly. According to our algorithm of space mapping between projections and capturing orientation exchange of our intra-oral scanning configuration, the system we made certainly can be proved to achieve the required accuracy of +/-10μm to deal with intra-oral scanning on the basis of utilizing active triangulation method. The final purpose aimed to the scanning of object surface profile with its size about 10x10x10mm3.

Multi-technique approach for deriving a VLBI signal extra-path variation model induced by gravity: the example of Medicina

NASA Astrophysics Data System (ADS)

Sarti, P.; Abbondanza, C.; Negusini, M.; Vittuari, L.

2009-09-01

During the measurement sessions gravity might induce significant deformations in large VLBI telescopes. If neglected or mismodelled, these deformations might bias the phase of the incoming signal thus corrupting the estimate of some crucial geodetic parameters (e.g. the height component of VLBI Reference Point). This paper describes a multi-technique approach implemented for measuring and quantifying the gravity-dependent deformations experienced by the 32-m diameter VLBI antenna of Medicina (Northern Italy). Such an approach integrates three different methods: Terrestrial Triangulations and Trilaterations (TTT), Laser Scanning (LS) and a Finite Element Model (FEM) of the antenna. The combination of the observations performed with these methods allows to accurately define an elevation-dependent model of the signal path variation which appears to be, for the Medicina telescope, non negligible. In the range [0,90] deg the signal path increases monotonically by almost 2 cm. The effect of such a variation has not been introduced in actual VLBI analysis yet; nevertheless this is the task we are going to pursue in the very next future.

Incremental triangulation by way of edge swapping and local optimization

NASA Technical Reports Server (NTRS)

Wiltberger, N. Lyn

1994-01-01

This document is intended to serve as an installation, usage, and basic theory guide for the two dimensional triangulation software 'HARLEY' written for the Silicon Graphics IRIS workstation. This code consists of an incremental triangulation algorithm based on point insertion and local edge swapping. Using this basic strategy, several types of triangulations can be produced depending on user selected options. For example, local edge swapping criteria can be chosen which minimizes the maximum interior angle (a MinMax triangulation) or which maximizes the minimum interior angle (a MaxMin or Delaunay triangulation). It should be noted that the MinMax triangulation is generally only locally optical (not globally optimal) in this measure. The MaxMin triangulation, however, is both locally and globally optical. In addition, Steiner triangulations can be constructed by inserting new sites at triangle circumcenters followed by edge swapping based on the MaxMin criteria. Incremental insertion of sites also provides flexibility in choosing cell refinement criteria. A dynamic heap structure has been implemented in the code so that once a refinement measure is specified (i.e., maximum aspect ratio or some measure of a solution gradient for the solution adaptive grid generation) the cell with the largest value of this measure is continually removed from the top of the heap and refined. The heap refinement strategy allows the user to specify either the number of cells desired or refine the mesh until all cell refinement measures satisfy a user specified tolerance level. Since the dynamic heap structure is constantly updated, the algorithm always refines the particular cell in the mesh with the largest refinement criteria value. The code allows the user to: triangulate a cloud of prespecified points (sites), triangulate a set of prespecified interior points constrained by prespecified boundary curve(s), Steiner triangulate the interior/exterior of prespecified boundary curve(s), refine existing triangulations based on solution error measures, and partition meshes based on the Cuthill-McKee, spectral, and coordinate bisection strategies.

Methodological triangulation in a study of social support for siblings of children with cancer.

PubMed

Murray, J S

1999-10-01

Triangulation is an approach to research that is becoming increasingly popular among nurse researchers. Five types of triangulation are used in nursing research: data, methodological, theoretical, researcher, and analytical triangulation. Methodological triangulation is an attempt to improve validity by combining various techniques in one study. In this article, an example of quantitative and qualitative triangulation is discussed to illustrate the procedures used and the results achieved. The secondary data used as an example are from a previous study that was conducted by the researcher and investigated nursing interventions used by pediatric oncology nurses to provide social support to siblings of children with cancer. Results show that methodological triangulation was beneficial in this study for three reasons. First, the careful comparison of quantitative and qualitative data added support for the social support variables under investigation. Second, the comparison showed more in-depth dimensions about pediatric oncology nurses providing social support to siblings of children with cancer. Finally, the use of methodological triangulation provided insight into revisions for the quantitative instrument.

Development of collision avoidance system for useful UAV applications using image sensors with laser transmitter

NASA Astrophysics Data System (ADS)

Cheong, M. K.; Bahiki, M. R.; Azrad, S.

2016-10-01

The main goal of this study is to demonstrate the approach of achieving collision avoidance on Quadrotor Unmanned Aerial Vehicle (QUAV) using image sensors with colour- based tracking method. A pair of high definition (HD) stereo cameras were chosen as the stereo vision sensor to obtain depth data from flat object surfaces. Laser transmitter was utilized to project high contrast tracking spot for depth calculation using common triangulation. Stereo vision algorithm was developed to acquire the distance from tracked point to QUAV and the control algorithm was designed to manipulate QUAV's response based on depth calculated. Attitude and position controller were designed using the non-linear model with the help of Optitrack motion tracking system. A number of collision avoidance flight tests were carried out to validate the performance of the stereo vision and control algorithm based on image sensors. In the results, the UAV was able to hover with fairly good accuracy in both static and dynamic collision avoidance for short range collision avoidance. Collision avoidance performance of the UAV was better with obstacle of dull surfaces in comparison to shiny surfaces. The minimum collision avoidance distance achievable was 0.4 m. The approach was suitable to be applied in short range collision avoidance.

Three-dimensional sensor system using multistripe laser and stereo camera for environment recognition of mobile robots

NASA Astrophysics Data System (ADS)

Kim, Min Young; Cho, Hyung Suck; Kim, Jae H.

2002-10-01

In recent years, intelligent autonomous mobile robots have drawn tremendous interests as service robots for serving human or industrial robots for replacing human. To carry out the task, robots must be able to sense and recognize 3D space that they live or work. In this paper, we deal with the topic related to 3D sensing system for the environment recognition of mobile robots. For this, the structured lighting is basically utilized for a 3D visual sensor system because of the robustness on the nature of the navigation environment and the easy extraction of feature information of interest. The proposed sensing system is classified into a trinocular vision system, which is composed of the flexible multi-stripe laser projector, and two cameras. The principle of extracting the 3D information is based on the optical triangulation method. With modeling the projector as another camera and using the epipolar constraints which the whole cameras makes, the point-to-point correspondence between the line feature points in each image is established. In this work, the principle of this sensor is described in detail, and a series of experimental tests is performed to show the simplicity and efficiency and accuracy of this sensor system for 3D the environment sensing and recognition.

Automatic anatomical structures location based on dynamic shape measurement

NASA Astrophysics Data System (ADS)

Witkowski, Marcin; Rapp, Walter; Sitnik, Robert; Kujawinska, Malgorzata; Vander Sloten, Jos; Haex, Bart; Bogaert, Nico; Heitmann, Kjell

2005-09-01

New image processing methods and active photonics apparatus have made possible the development of relatively inexpensive optical systems for complex shape and object measurements. We present dynamic 360° scanning method for analysis of human lower body biomechanics, with an emphasis on the analysis of the knee joint. The anatomical structure (of high medical interest) that is possible to scan and analyze, is patella. Tracking of patella position and orientation under dynamic conditions may lead to detect pathological patella movements and help in knee joint disease diagnosis. The processed data is obtained from a dynamic laser triangulation surface measurement system, able to capture slow to normal movements with a scan frequency between 15 and 30 Hz. These frequency rates are enough to capture controlled movements used e.g. for medical examination purposes. The purpose of the work presented is to develop surface analysis methods that may be used as support of diagnosis of motoric abilities of lower limbs. The paper presents algorithms used to process acquired lower limbs surface data in order to find the position and orientation of patella. The algorithms implemented include input data preparation, curvature description methods, knee region discrimination and patella assumed position/orientation calculation. Additionally, a method of 4D (3D + time) medical data visualization is proposed. Also some exemplary results are presented.

Adolescent Triangulation into Parental Conflicts: Longitudinal Implications for Appraisals and Adolescent-Parent Relations

ERIC Educational Resources Information Center

Fosco, Gregory M.; Grych, John H.

2010-01-01

Although triangulation into parental conflict is a risk factor for child and adolescent maladjustment, little is known about how triangulation affects adolescents' functioning or the factors that lead children to be drawn into parental disagreements. This prospective study examined the relations between triangulation, appraisals of conflict, and…

A tuned mesh-generation strategy for image representation based on data-dependent triangulation.

PubMed

Li, Ping; Adams, Michael D

2013-05-01

A mesh-generation framework for image representation based on data-dependent triangulation is proposed. The proposed framework is a modified version of the frameworks of Rippa and Garland and Heckbert that facilitates the development of more effective mesh-generation methods. As the proposed framework has several free parameters, the effects of different choices of these parameters on mesh quality are studied, leading to the recommendation of a particular set of choices for these parameters. A mesh-generation method is then introduced that employs the proposed framework with these best parameter choices. This method is demonstrated to produce meshes of higher quality (both in terms of squared error and subjectively) than those generated by several competing approaches, at a relatively modest computational and memory cost.

Personal authentication using hand vein triangulation and knuckle shape.

PubMed

Kumar, Ajay; Prathyusha, K Venkata

2009-09-01

This paper presents a new approach to authenticate individuals using triangulation of hand vein images and simultaneous extraction of knuckle shape information. The proposed method is fully automated and employs palm dorsal hand vein images acquired from the low-cost, near infrared, contactless imaging. The knuckle tips are used as key points for the image normalization and extraction of region of interest. The matching scores are generated in two parallel stages: (i) hierarchical matching score from the four topologies of triangulation in the binarized vein structures and (ii) from the geometrical features consisting of knuckle point perimeter distances in the acquired images. The weighted score level combination from these two matching scores are used to authenticate the individuals. The achieved experimental results from the proposed system using contactless palm dorsal-hand vein images are promising (equal error rate of 1.14%) and suggest more user friendly alternative for user identification.

Mixed method evaluation of a community-based physical activity program using the RE-AIM framework: practical application in a real-world setting.

PubMed

Koorts, Harriet; Gillison, Fiona

2015-11-06

Communities are a pivotal setting in which to promote increases in child and adolescent physical activity behaviours. Interventions implemented in these settings require effective evaluation to facilitate translation of findings to wider settings. The aims of this paper are to i) present findings from a RE-AIM evaluation of a community-based physical activity program, and ii) review the methodological challenges faced when applying RE-AIM in practice. A single mixed-methods case study was conducted based on a concurrent triangulation design. Five sources of data were collected via interviews, questionnaires, archival records, documentation and field notes. Evidence was triangulated within RE-AIM to assess individual and organisational-level program outcomes. Inconsistent availability of data and a lack of robust reporting challenged assessment of all five dimensions. Reach, Implementation and setting-level Adoption were less successful, Effectiveness and Maintenance at an individual and organisational level were moderately successful. Only community-level Adoption was highly successful, reflecting the key program goal to provide community-wide participation in sport and physical activity. This research highlighted important methodological constraints associated with the use of RE-AIM in practice settings. Future evaluators wishing to use RE-AIM may benefit from a mixed-method triangulation approach to offset challenges with data availability and reliability.

A Mixed Methods and Triangulation Model for Increasing the Accuracy of Adherence and Sexual Behaviour Data: The Microbicides Development Programme

PubMed Central

Pool, Robert; Montgomery, Catherine M.; Morar, Neetha S.; Mweemba, Oliver; Ssali, Agnes; Gafos, Mitzy; Lees, Shelley; Stadler, Jonathan; Crook, Angela; Nunn, Andrew; Hayes, Richard; McCormack, Sheena

2010-01-01

Background The collection of accurate data on adherence and sexual behaviour is crucial in microbicide (and other HIV-related) research. In the absence of a “gold standard” the collection of such data relies largely on participant self-reporting. After reviewing available methods, this paper describes a mixed method/triangulation model for generating more accurate data on adherence and sexual behaviour in a multi-centre vaginal microbicide clinical trial. In a companion paper some of the results from this model are presented [1]. Methodology/Principal Findings Data were collected from a random subsample of 725 women (7.7% of the trial population) using structured interviews, coital diaries, in-depth interviews, counting returned gel applicators, focus group discussions, and ethnography. The core of the model was a customised, semi-structured in-depth interview. There were two levels of triangulation: first, discrepancies between data from the questionnaires, diaries, in-depth interviews and applicator returns were identified, discussed with participants and, to a large extent, resolved; second, results from individual participants were related to more general data emerging from the focus group discussions and ethnography. A democratic and equitable collaboration between clinical trialists and qualitative social scientists facilitated the success of the model, as did the preparatory studies preceding the trial. The process revealed some of the underlying assumptions and routinised practices in “clinical trial culture” that are potentially detrimental to the collection of accurate data, as well as some of the shortcomings of large qualitative studies, and pointed to some potential solutions. Conclusions/Significance The integration of qualitative social science and the use of mixed methods and triangulation in clinical trials are feasible, and can reveal (and resolve) inaccuracies in data on adherence and sensitive behaviours, as well as illuminating aspects of “trial culture” that may also affect data accuracy. PMID:20657778

Gravity-dependent signal path variation in a large VLBI telescope modelled with a combination of surveying methods

NASA Astrophysics Data System (ADS)

Sarti, Pierguido; Abbondanza, C.; Vittuari, L.

2009-11-01

The very long baseline interferometry (VLBI) antenna in Medicina (Italy) is a 32-m AZ-EL mount that was surveyed several times, adopting an indirect method, for the purpose of estimating the eccentricity vector between the co-located VLBI and Global Positioning System instruments. In order to fulfill this task, targets were located in different parts of the telescope’s structure. Triangulation and trilateration on the targets highlight a consistent amount of deformation that biases the estimate of the instrument’s reference point up to 1 cm, depending on the targets’ locations. Therefore, whenever the estimation of accurate local ties is needed, it is critical to take into consideration the action of gravity on the structure. Furthermore, deformations induced by gravity on VLBI telescopes may modify the length of the path travelled by the incoming radio signal to a non-negligible extent. As a consequence, differently from what it is usually assumed, the relative distance of the feed horn’s phase centre with respect to the elevation axis may vary, depending on the telescope’s pointing elevation. The Medicina telescope’s signal path variation Δ L increases by a magnitude of approximately 2 cm, as the pointing elevation changes from horizon to zenith; it is described by an elevation-dependent second-order polynomial function computed as, according to Clark and Thomsen (Techical report, 100696, NASA, Greenbelt, 1988), a linear combination of three terms: receiver displacement Δ R, primary reflector’s vertex displacement Δ V and focal length variations Δ F. Δ L was investigated with a combination of terrestrial triangulation and trilateration, laser scanning and a finite element model of the antenna. The antenna gain (or auto-focus curve) Δ G is routinely determined through astronomical observations. A surprisingly accurate reproduction of Δ G can be obtained with a combination of Δ V, Δ F and Δ R.

Watching Grass - a Pilot Study on the Suitability of Photogrammetric Techniques for Quantifying Change in Aboveground Biomass in Grassland Experiments

NASA Astrophysics Data System (ADS)

Kröhnert, M.; Anderson, R.; Bumberger, J.; Dietrich, P.; Harpole, W. S.; Maas, H.-G.

2018-05-01

Grassland ecology experiments in remote locations requiring quantitative analysis of the biomass in defined plots are becoming increasingly widespread, but are still limited by manual sampling methodologies. To provide a cost-effective automated solution for biomass determination, several photogrammetric techniques are examined to generate 3D point cloud representations of plots as a basis, to estimate aboveground biomass on grassland plots, which is a key ecosystem variable used in many experiments. Methods investigated include Structure from Motion (SfM) techniques for camera pose estimation with posterior dense matching as well as the usage of a Time of Flight (TOF) 3D camera, a laser light sheet triangulation system and a coded light projection system. In this context, plants of small scales (herbage) and medium scales are observed. In the first pilot study presented here, the best results are obtained by applying dense matching after SfM, ideal for integration into distributed experiment networks.

Three-dimensional tracking and imaging laser scanner for space operations

NASA Astrophysics Data System (ADS)

Laurin, Denis G.; Beraldin, J. A.; Blais, Francois; Rioux, Marc; Cournoyer, Luc

1999-05-01

This paper presents the development of a laser range scanner (LARS) as a three-dimensional sensor for space applications. The scanner is a versatile system capable of doing surface imaging, target ranging and tracking. It is capable of short range (0.5 m to 20 m) and long range (20 m to 10 km) sensing using triangulation and time-of-flight (TOF) methods respectively. At short range (1 m), the resolution is sub-millimeter and drops gradually with distance (2 cm at 10 m). For long range, the TOF provides a constant resolution of plus or minus 3 cm, independent of range. The LARS could complement the existing Canadian Space Vision System (CSVS) for robotic manipulation. As an active vision system, the LARS is immune to sunlight and adverse lighting; this is a major advantage over the CSVS, as outlined in this paper. The LARS could also replace existing radar systems used for rendezvous and docking. There are clear advantages of an optical system over a microwave radar in terms of size, mass, power and precision. Equipped with two high-speed galvanometers, the laser can be steered to address any point in a 30 degree X 30 degree field of view. The scanning can be continuous (raster scan, Lissajous) or direct (random). This gives the scanner the ability to register high-resolution 3D images of range and intensity (up to 4000 X 4000 pixels) and to perform point target tracking as well as object recognition and geometrical tracking. The imaging capability of the scanner using an eye-safe laser is demonstrated. An efficient fiber laser delivers 60 mW of CW or 3 (mu) J pulses at 20 kHz for TOF operation. Implementation of search and track of multiple targets is also demonstrated. For a single target, refresh rates up to 137 Hz is possible. Considerations for space qualification of the scanner are discussed. Typical space operations, such as docking, object attitude tracking, and inspections are described.

Orthodontics: computer-aided diagnosis and treatment planning

NASA Astrophysics Data System (ADS)

Yi, Yaxing; Li, Zhongke; Wei, Suyuan; Deng, Fanglin; Yao, Sen

2000-10-01

The purpose of this article is to introduce the outline of our newly developed computer-aided 3D dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a scanning device and a personal computer as a scanning controller and post processor. The scanning device is composed of a laser beam emitter, two sets of linear CCD cameras and a table which is rotatable by two-degree-of-freedom. The rotating is controlled precisely by a personal computer. The dental cast is projected and scanned with a laser beam. Triangulation is applied to determine the location of each point. Generation of 3D graphics of the dental cast takes approximately 40 minutes. About 170,000 sets of X,Y,Z coordinates are store for one dental cast. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the top surface area of each molar. The advantage of this system is that it facilitates the otherwise complicated and time- consuming mock surgery necessary for treatment planning in orthognathic surgery.

Optoelectronic scanning system upgrade by energy center localization methods

NASA Astrophysics Data System (ADS)

Flores-Fuentes, W.; Sergiyenko, O.; Rodriguez-Quiñonez, J. C.; Rivas-López, M.; Hernández-Balbuena, D.; Básaca-Preciado, L. C.; Lindner, L.; González-Navarro, F. F.

2016-11-01

A problem of upgrading an optoelectronic scanning system with digital post-processing of the signal based on adequate methods of energy center localization is considered. An improved dynamic triangulation analysis technique is proposed by an example of industrial infrastructure damage detection. A modification of our previously published method aimed at searching for the energy center of an optoelectronic signal is described. Application of the artificial intelligence algorithm of compensation for the error of determining the angular coordinate in calculating the spatial coordinate through dynamic triangulation is demonstrated. Five energy center localization methods are developed and tested to select the best method. After implementation of these methods, digital compensation for the measurement error, and statistical data analysis, a non-parametric behavior of the data is identified. The Wilcoxon signed rank test is applied to improve the result further. For optical scanning systems, it is necessary to detect a light emitter mounted on the infrastructure being investigated to calculate its spatial coordinate by the energy center localization method.

Unimodular lattice triangulations as small-world and scale-free random graphs

NASA Astrophysics Data System (ADS)

Krüger, B.; Schmidt, E. M.; Mecke, K.

2015-02-01

Real-world networks, e.g., the social relations or world-wide-web graphs, exhibit both small-world and scale-free behaviour. We interpret lattice triangulations as planar graphs by identifying triangulation vertices with graph nodes and one-dimensional simplices with edges. Since these triangulations are ergodic with respect to a certain Pachner flip, applying different Monte Carlo simulations enables us to calculate average properties of random triangulations, as well as canonical ensemble averages, using an energy functional that is approximately the variance of the degree distribution. All considered triangulations have clustering coefficients comparable with real-world graphs; for the canonical ensemble there are inverse temperatures with small shortest path length independent of system size. Tuning the inverse temperature to a quasi-critical value leads to an indication of scale-free behaviour for degrees k≥slant 5. Using triangulations as a random graph model can improve the understanding of real-world networks, especially if the actual distance of the embedded nodes becomes important.

Delaunay Triangulation as a New Coverage Measurement Method in Wireless Sensor Network

PubMed Central

Chizari, Hassan; Hosseini, Majid; Poston, Timothy; Razak, Shukor Abd; Abdullah, Abdul Hanan

2011-01-01

Sensing and communication coverage are among the most important trade-offs in Wireless Sensor Network (WSN) design. A minimum bound of sensing coverage is vital in scheduling, target tracking and redeployment phases, as well as providing communication coverage. Some methods measure the coverage as a percentage value, but detailed information has been missing. Two scenarios with equal coverage percentage may not have the same Quality of Coverage (QoC). In this paper, we propose a new coverage measurement method using Delaunay Triangulation (DT). This can provide the value for all coverage measurement tools. Moreover, it categorizes sensors as ‘fat’, ‘healthy’ or ‘thin’ to show the dense, optimal and scattered areas. It can also yield the largest empty area of sensors in the field. Simulation results show that the proposed DT method can achieve accurate coverage information, and provides many tools to compare QoC between different scenarios. PMID:22163792

The on-orbit calibration of geometric parameters of the Tian-Hui 1 (TH-1) satellite

NASA Astrophysics Data System (ADS)

Wang, Jianrong; Wang, Renxiang; Hu, Xin; Su, Zhongbo

2017-02-01

The on-orbit calibration of geometric parameters is a key step in improving the location accuracy of satellite images without using Ground Control Points (GCPs). Most methods of on-orbit calibration are based on the self-calibration using additional parameters. When using additional parameters, different number of additional parameters may lead to different results. The triangulation bundle adjustment is another way to calibrate the geometric parameters of camera, which can describe the changes in each geometric parameter. When triangulation bundle adjustment method is applied to calibrate geometric parameters, a prerequisite is that the strip model can avoid systematic deformation caused by the rate of attitude changes. Concerning the stereo camera, the influence of the intersection angle should be considered during calibration. The Equivalent Frame Photo (EFP) bundle adjustment based on the Line-Matrix CCD (LMCCD) image can solve the systematic distortion of the strip model, and obtain high accuracy location without using GCPs. In this paper, the triangulation bundle adjustment is used to calibrate the geometric parameters of TH-1 satellite cameras based on LMCCD image. During the bundle adjustment, the three-line array cameras are reconstructed by adopting the principle of inverse triangulation. Finally, the geometric accuracy is validated before and after on-orbit calibration using 5 testing fields. After on-orbit calibration, the 3D geometric accuracy is improved to 11.8 m from 170 m. The results show that the location accuracy of TH-1 without using GCPs is significantly improved using the on-orbit calibration of the geometric parameters.

An efficient photogrammetric stereo matching method for high-resolution images

NASA Astrophysics Data System (ADS)

Li, Yingsong; Zheng, Shunyi; Wang, Xiaonan; Ma, Hao

2016-12-01

Stereo matching of high-resolution images is a great challenge in photogrammetry. The main difficulty is the enormous processing workload that involves substantial computing time and memory consumption. In recent years, the semi-global matching (SGM) method has been a promising approach for solving stereo problems in different data sets. However, the time complexity and memory demand of SGM are proportional to the scale of the images involved, which leads to very high consumption when dealing with large images. To solve it, this paper presents an efficient hierarchical matching strategy based on the SGM algorithm using single instruction multiple data instructions and structured parallelism in the central processing unit. The proposed method can significantly reduce the computational time and memory required for large scale stereo matching. The three-dimensional (3D) surface is reconstructed by triangulating and fusing redundant reconstruction information from multi-view matching results. Finally, three high-resolution aerial date sets are used to evaluate our improvement. Furthermore, precise airborne laser scanner data of one data set is used to measure the accuracy of our reconstruction. Experimental results demonstrate that our method remarkably outperforms in terms of time and memory savings while maintaining the density and precision of the 3D cloud points derived.

Shared decision-making in medical encounters regarding breast cancer treatment: the contribution of methodological triangulation.

PubMed

Durif-Bruckert, C; Roux, P; Morelle, M; Mignotte, H; Faure, C; Moumjid-Ferdjaoui, N

2015-07-01

The aim of this study on shared decision-making in the doctor-patient encounter about surgical treatment for early-stage breast cancer, conducted in a regional cancer centre in France, was to further the understanding of patient perceptions on shared decision-making. The study used methodological triangulation to collect data (both quantitative and qualitative) about patient preferences in the context of a clinical consultation in which surgeons followed a shared decision-making protocol. Data were analysed from a multi-disciplinary research perspective (social psychology and health economics). The triangulated data collection methods were questionnaires (n = 132), longitudinal interviews (n = 47) and observations of consultations (n = 26). Methodological triangulation revealed levels of divergence and complementarity between qualitative and quantitative results that suggest new perspectives on the three inter-related notions of decision-making, participation and information. Patients' responses revealed important differences between shared decision-making and participation per se. The authors note that subjecting patients to a normative behavioural model of shared decision-making in an era when paradigms of medical authority are shifting may undermine the patient's quest for what he or she believes is a more important right: a guarantee of the best care available. © 2014 John Wiley & Sons Ltd.

Revisiting Individual Creativity Assessment: Triangulation in Subjective and Objective Assessment Methods

ERIC Educational Resources Information Center

Park, Namgyoo K.; Chun, Monica Youngshin; Lee, Jinju

2016-01-01

Compared to the significant development of creativity studies, individual creativity research has not reached a meaningful consensus regarding the most valid and reliable method for assessing individual creativity. This study revisited 2 of the most popular methods for assessing individual creativity: subjective and objective methods. This study…

Computing convex quadrangulations☆

PubMed Central

Schiffer, T.; Aurenhammer, F.; Demuth, M.

2012-01-01

We use projected Delaunay tetrahedra and a maximum independent set approach to compute large subsets of convex quadrangulations on a given set of points in the plane. The new method improves over the popular pairing method based on triangulating the point set. PMID:22389540

Delaunay Refinement Mesh Generation

DTIC Science & Technology

1997-05-18

edge is locally Delaunay; thus, by Lemma 3, every edge is Delaunay. Theorem 5 Let V be a set of three or more vertices in the plane that are not all...this document. Delaunay triangulations are valuable in part because they have the following optimality properties. Theorem 6 Among all triangulations of...no locally Delaunay edges. By Theorem 5, a triangulation with no locally Delaunay edges is the Delaunay triangulation. The property of max-min

Applications and requirements for MEMS scanner mirrors

NASA Astrophysics Data System (ADS)

Wolter, Alexander; Hsu, Shu-Ting; Schenk, Harald; Lakner, Hubert K.

2005-01-01

Micro scanning mirrors are quite versatile MEMS devices for the deflection of a laser beam or a shaped beam from another light source. The most exciting application is certainly in laser-scanned displays. Laser television, home cinema and data projectors will display the most brilliant colors exceeding even plasma, OLED and CRT. Devices for front and rear projection will have advantages in size, weight and price. These advantages will be even more important in near-eye virtual displays like head-mounted displays or viewfinders in digital cameras and potentially in UMTS handsets. Optical pattern generation by scanning a modulated beam over an area can be used also in a number of other applications: laser printers, direct writing of photo resist for printed circuit boards or laser marking and with higher laser power laser ablation or material processing. Scanning a continuous laser beam over a printed pattern and analyzing the scattered reflection is the principle of barcode reading in 1D and 2D. This principle works also for identification of signatures, coins, bank notes, vehicles and other objects. With a focused white-light or RGB beam even full color imaging with high resolution is possible from an amazingly small device. The form factor is also very interesting for the application in endoscopes. Further applications are light curtains for intrusion control and the generation of arbitrary line patterns for triangulation. Scanning a measurement beam extends point measurements to 1D or 2D scans. Automotive LIDAR (laser RADAR) or scanning confocal microscopy are just two examples. Last but not least there is the field of beam steering. E.g. for all-optical fiber switches or positioning of read-/write heads in optical storage devices. The variety of possible applications also brings a variety of specifications. This publication discusses various applications and their requirements.

The relationships between stressful life events during childhood and differentiation of self and intergenerational triangulation in adulthood.

PubMed

Peleg, Ora

2014-12-01

This study examined the relationships between stressful life events in childhood and differentiation of self and intergenerational triangulation in adulthood. The sample included 217 students (173 females and 44 males) from a college in northern Israel. Participants completed the Hebrew versions of Life Events Checklist (LEC), Differentiation of Self Inventory-Revised (DSI-R) and intergenerational triangulation (INTRI). The main findings were that levels of stressful life events during childhood and adolescence among both genders were positively correlated with the levels of fusion with others and intergenerational triangulation. The levels of positive life events were negatively related to levels of emotional reactivity, emotional cut-off and intergenerational triangulation. Levels of stressful life events in females were positively correlated with emotional reactivity. Intergenerational triangulation was correlated with emotional reactivity, emotional cut-off, fusion with others and I-position. Findings suggest that families that experience higher levels of stressful life events may be at risk for higher levels of intergenerational triangulation and lower levels of differentiation of self. © 2014 International Union of Psychological Science.

3D shape measurement with thermal pattern projection

NASA Astrophysics Data System (ADS)

Brahm, Anika; Reetz, Edgar; Schindwolf, Simon; Correns, Martin; Kühmstedt, Peter; Notni, Gunther

2016-12-01

Structured light projection techniques are well-established optical methods for contactless and nondestructive three-dimensional (3D) measurements. Most systems operate in the visible wavelength range (VIS) due to commercially available projection and detection technology. For example, the 3D reconstruction can be done with a stereo-vision setup by finding corresponding pixels in both cameras followed by triangulation. Problems occur, if the properties of object materials disturb the measurements, which are based on the measurement of diffuse light reflections. For example, there are existing materials in the VIS range that are too transparent, translucent, high absorbent, or reflective and cannot be recorded properly. To overcome these challenges, we present an alternative thermal approach that operates in the infrared (IR) region of the electromagnetic spectrum. For this purpose, we used two cooled mid-wave (MWIR) cameras (3-5 μm) to detect emitted heat patterns, which were introduced by a CO2 laser. We present a thermal 3D system based on a GOBO (GOes Before Optics) wheel projection unit and first 3D analyses for different system parameters and samples. We also show a second alternative approach based on an incoherent (heat) source, to overcome typical disadvantages of high-power laser-based systems, such as industrial health and safety considerations, as well as high investment costs. Thus, materials like glass or fiber-reinforced composites can be measured contactless and without the need of additional paintings.

Evaluation and correction of laser-scanned point clouds

NASA Astrophysics Data System (ADS)

Teutsch, Christian; Isenberg, Tobias; Trostmann, Erik; Weber, Michael; Berndt, Dirk; Strothotte, Thomas

2005-01-01

The digitalization of real-world objects is of great importance in various application domains. E.g. in industrial processes quality assurance is very important. Geometric properties of workpieces have to be measured. Traditionally, this is done with gauges which is somewhat subjective and time-consuming. We developed a robust optical laser scanner for the digitalization of arbitrary objects, primary, industrial workpieces. As measuring principle we use triangulation with structured lighting and a multi-axis locomotor system. Measurements on the generated data leads to incorrect results if the contained error is too high. Therefore, processes for geometric inspection under non-laboratory conditions are needed that are robust in permanent use and provide high accuracy as well as high operation speed. The many existing methods for polygonal mesh optimization produce very esthetic 3D models but often require user interaction and are limited in processing speed and/or accuracy. Furthermore, operations on optimized meshes consider the entire model and pay only little attention to individual measurements. However, many measurements contribute to parts or single scans with possibly strong differences between neighboring scans being lost during mesh construction. Also, most algorithms consider unsorted point clouds although the scanned data is structured through device properties and measuring principles. We use this underlying structure to achieve high processing speeds and extract intrinsic system parameters and use them for fast pre-processing.

Modulated Acquisition of Spatial Distortion Maps

PubMed Central

Volkov, Alexey; Gros, Jerneja Žganec; Žganec, Mario; Javornik, Tomaž; Švigelj, Aleš

2013-01-01

This work discusses a novel approach to image acquisition which improves the robustness of captured data required for 3D range measurements. By applying a pseudo-random code modulation to sequential acquisition of projected patterns the impact of environmental factors such as ambient light and mutual interference is significantly reduced. The proposed concept has been proven with an experimental range sensor based on the laser triangulation principle. The proposed design can potentially enhance the use of this principle to a variety of outdoor applications, such as autonomous vehicles, pedestrians' safety, collision avoidance, and many other tasks, where robust real-time distance detection in real world environment is crucial. PMID:23966196

Modulated acquisition of spatial distortion maps.

PubMed

Volkov, Alexey; Gros, Jerneja Zganec; Zganec, Mario; Javornik, Tomaž; Svigelj, Aleš

2013-08-21

This work discusses a novel approach to image acquisition which improves the robustness of captured data required for 3D range measurements. By applying a pseudo-random code modulation to sequential acquisition of projected patterns the impact of environmental factors such as ambient light and mutual interference is significantly reduced. The proposed concept has been proven with an experimental range sensor based on the laser triangulation principle. The proposed design can potentially enhance the use of this principle to a variety of outdoor applications, such as autonomous vehicles, pedestrians' safety, collision avoidance, and many other tasks, where robust real-time distance detection in real world environment is crucial.

Importance of Laser Scanning Resolution in the Process of Recreating the Architectural Details of Historical Buildings

NASA Astrophysics Data System (ADS)

Pawłowicz, Joanna A.

2017-10-01

The TLS method (Terrestrial Laser Scanning) may replace the traditional building survey methods, e.g. those requiring the use measuring tapes or range finders. This technology allows for collecting digital data in the form of a point cloud, which can be used to create a 3D model of a building. In addition, it allows for collecting data with an incredible precision, which translates into the possibility to reproduce all architectural features of a building. This data is applied in reverse engineering to create a 3D model of an object existing in a physical space. This study presents the results of a research carried out using a point cloud to recreate the architectural features of a historical building with the application of reverse engineering. The research was conducted on a two-storey residential building with a basement and an attic. Out of the building’s façade sticks a veranda featuring a complicated, wooden structure. The measurements were taken at the medium and the highest resolution using a ScanStation C10 laser scanner by Leica. The data obtained was processed using specialist software, which allowed for the application of reverse engineering, especially for reproducing the sculpted details of the veranda. Following digitization, all redundant data was removed from the point cloud and the cloud was subjected to modelling. For testing purposes, a selected part of the veranda was modelled by means of two methods: surface matching and Triangulated Irregular Network. Both modelling methods were applied in the case of data collected at medium and the highest resolution. Creating a model based on data obtained at medium resolution, both by means of the surface matching and the TIN method, does not allow for a precise recreation of architectural details. The study presents certain sculpted elements recreated based on the highest resolution data with superimposed TIN juxtaposed against a digital image. The resulting model is very precise. Creating good models requires highly accurate field data. It is important to properly choose the distance between the measuring station and the measured object in order to ensure that the angles of incidence (horizontal and vertical) of the laser beam are as straight as possible. The model created based on medium resolution offers very poor quality of details, i.e. only the bigger, basic elements of each detail are clearly visible, while the smaller ones are blurred. This is why in order to obtain data sufficient to reproduce architectural details laser scanning should be performed at the highest resolution. In addition, modelling by means of the surface matching method should be avoided - a better idea is to use the TIN method. In addition to providing a realistically-looking visualization, the method has one more important advantage - it is 4 times faster than the surface matching method.

Multidirectional four-dimensional shape measurement system

NASA Astrophysics Data System (ADS)

Lenar, Janusz; Sitnik, Robert; Witkowski, Marcin

2012-03-01

Currently, a lot of different scanning techniques are used for 3D imaging of human body. Most of existing systems are based on static registration of internal structures using MRI or CT techniques as well as 3D scanning of outer surface of human body by laser triangulation or structured light methods. On the other hand there is an existing mature 4D method based on tracking in time the position of retro-reflective markers attached to human body. There are two main drawbacks of this solution: markers are attached to skin (no real skeleton movement is registered) and it gives (x, y, z, t) coordinates only in those points (not for the whole surface). In this paper we present a novel multidirectional structured light measurement system that is capable of measuring 3D shape of human body surface with frequency reaching 60Hz. The developed system consists of two spectrally separated and hardware-synchronized 4D measurement heads. The principle of the measurement is based on single frame analysis. Projected frame is composed from sine-modulated intensity pattern and a special stripe allowing absolute phase measurement. Several different geometrical set-ups will be proposed depending on type of movements that are to be registered.

Feature-constrained surface reconstruction approach for point cloud data acquired with 3D laser scanner

NASA Astrophysics Data System (ADS)

Wang, Yongbo; Sheng, Yehua; Lu, Guonian; Tian, Peng; Zhang, Kai

2008-04-01

Surface reconstruction is an important task in the field of 3d-GIS, computer aided design and computer graphics (CAD & CG), virtual simulation and so on. Based on available incremental surface reconstruction methods, a feature-constrained surface reconstruction approach for point cloud is presented. Firstly features are extracted from point cloud under the rules of curvature extremes and minimum spanning tree. By projecting local sample points to the fitted tangent planes and using extracted features to guide and constrain the process of local triangulation and surface propagation, topological relationship among sample points can be achieved. For the constructed models, a process named consistent normal adjustment and regularization is adopted to adjust normal of each face so that the correct surface model is achieved. Experiments show that the presented approach inherits the convenient implementation and high efficiency of traditional incremental surface reconstruction method, meanwhile, it avoids improper propagation of normal across sharp edges, which means the applicability of incremental surface reconstruction is greatly improved. Above all, appropriate k-neighborhood can help to recognize un-sufficient sampled areas and boundary parts, the presented approach can be used to reconstruct both open and close surfaces without additional interference.

Moments, Mixed Methods, and Paradigm Dialogs

ERIC Educational Resources Information Center

Denzin, Norman K.

2010-01-01

I reread the 50-year-old history of the qualitative inquiry that calls for triangulation and mixed methods. I briefly visit the disputes within the mixed methods community asking how did we get to where we are today, the period of mixed-multiple-methods advocacy, and Teddlie and Tashakkori's third methodological moment. (Contains 10 notes.)

Symbolic Drawings Reveal Changes in Preservice Teacher Mathematics Attitudes after a Mathematics Methods Course

ERIC Educational Resources Information Center

Rule, Audrey C.; Harrell, Mary H.

2006-01-01

A new method of analyzing mathematics attitudes through symbolic drawings, situated within the field of Jungian-oriented analytical psychology, was applied to 52 preservice elementary teachers before and after a mathematics methods course. In this triangulation mixed methods design study, pretest images related to past mathematics experiences…

Airburst height computation method of Sea-Impact Test

NASA Astrophysics Data System (ADS)

Kim, Jinho; Kim, Hyungsup; Chae, Sungwoo; Park, Sungho

2017-05-01

This paper describes the ways how to measure the airburst height of projectiles and rockets. In general, the airburst height could be determined by using triangulation method or the images from the camera installed on the radar. There are some limitations in these previous methods when the missiles impact the sea surface. To apply triangulation method, the cameras should be installed so that the lines of sight intersect at angles from 60 to 120 degrees. There could be no effective observation towers to install the optical system. In case the range of the missile is more than 50km, the images from the camera of the radar could be useless. This paper proposes the method to measure the airburst height of sea impact projectile by using a single camera. The camera would be installed on the island near to the impact area and the distance could be computed by using the position and attitude of camera and sea level. To demonstrate the proposed method, the results from the proposed method are compared with that from the previous method.

Theory, Method, and Triangulation in the Study of Street Children.

ERIC Educational Resources Information Center

Lucchini, Riccardo

1996-01-01

Describes how a comparative study of street children in Montevideo (Uruguay), Rio de Janeiro, and Mexico City contributes to a synergism between theory and method. Notes how theoretical approaches of symbolic interactionism, genetic structuralism, and habitus theory complement interview, participant observation, and content analysis methods;…

Identifying the 630 nm auroral arc emission height: A comparison of the triangulation, FAC profile, and electron density methods

NASA Astrophysics Data System (ADS)

Megan Gillies, D.; Knudsen, D.; Donovan, E.; Jackel, B.; Gillies, R.; Spanswick, E.

2017-08-01

We present a comprehensive survey of 630 nm (red-line) emission discrete auroral arcs using the newly deployed Redline Emission Geospace Observatory. In this study we discuss the need for observations of 630 nm aurora and issues with the large-altitude range of the red-line aurora. We compare field-aligned currents (FACs) measured by the Swarm constellation of satellites with the location of 10 red-line (630 nm) auroral arcs observed by all-sky imagers (ASIs) and find that a characteristic emission height of 200 km applied to the ASI maps gives optimal agreement between the two observations. We also compare the new FAC method against the traditional triangulation method using pairs of all-sky imagers (ASIs), and against electron density profiles obtained from the Resolute Bay Incoherent Scatter Radar-Canadian radar, both of which are consistent with a characteristic emission height of 200 km.

Two Strategies for Qualitative Content Analysis: An Intramethod Approach to Triangulation.

PubMed

Renz, Susan M; Carrington, Jane M; Badger, Terry A

2018-04-01

The overarching aim of qualitative research is to gain an understanding of certain social phenomena. Qualitative research involves the studied use and collection of empirical materials, all to describe moments and meanings in individuals' lives. Data derived from these various materials require a form of analysis of the content, focusing on written or spoken language as communication, to provide context and understanding of the message. Qualitative research often involves the collection of data through extensive interviews, note taking, and tape recording. These methods are time- and labor-intensive. With the advances in computerized text analysis software, the practice of combining methods to analyze qualitative data can assist the researcher in making large data sets more manageable and enhance the trustworthiness of the results. This article will describe a novel process of combining two methods of qualitative data analysis, or Intramethod triangulation, as a means to provide a deeper analysis of text.

Enhancing Breast Cancer Recurrence Algorithms Through Selective Use of Medical Record Data

PubMed Central

Chubak, Jessica; Johnson, Lisa; Castillo, Adrienne; Weltzien, Erin; Caan, Bette J.

2016-01-01

Abstract Background: The utility of data-based algorithms in research has been questioned because of errors in identification of cancer recurrences. We adapted previously published breast cancer recurrence algorithms, selectively using medical record (MR) data to improve classification. Methods: We evaluated second breast cancer event (SBCE) and recurrence-specific algorithms previously published by Chubak and colleagues in 1535 women from the Life After Cancer Epidemiology (LACE) and 225 women from the Women’s Health Initiative cohorts and compared classification statistics to published values. We also sought to improve classification with minimal MR examination. We selected pairs of algorithms—one with high sensitivity/high positive predictive value (PPV) and another with high specificity/high PPV—using MR information to resolve discrepancies between algorithms, properly classifying events based on review; we called this “triangulation.” Finally, in LACE, we compared associations between breast cancer survival risk factors and recurrence using MR data, single Chubak algorithms, and triangulation. Results: The SBCE algorithms performed well in identifying SBCE and recurrences. Recurrence-specific algorithms performed more poorly than published except for the high-specificity/high-PPV algorithm, which performed well. The triangulation method (sensitivity = 81.3%, specificity = 99.7%, PPV = 98.1%, NPV = 96.5%) improved recurrence classification over two single algorithms (sensitivity = 57.1%, specificity = 95.5%, PPV = 71.3%, NPV = 91.9%; and sensitivity = 74.6%, specificity = 97.3%, PPV = 84.7%, NPV = 95.1%), with 10.6% MR review. Triangulation performed well in survival risk factor analyses vs analyses using MR-identified recurrences. Conclusions: Use of multiple recurrence algorithms in administrative data, in combination with selective examination of MR data, may improve recurrence data quality and reduce research costs. PMID:26582243

An overview of the stereo correlation and triangulation formulations used in DICe.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, Daniel Z.

This document provides a detailed overview of the stereo correlation algorithm and triangulation formulation used in the Digital Image Correlation Engine (DICe) to triangulate three dimensional motion in space given the image coordinates and camera calibration parameters.

Evaluation of Bone Healing After Osteotomies Prepared With Er:YAG Laser in Contact and Noncontact Modes and Piezosurgery--An Animal Study.

PubMed

Gabrić, Dragana; Blašković, Marko; Gjorgijevska, Elizabeta; Mladenov, Mitko; Tašič, Blaž; Jurič, Ivona Bago; Ban, Ticijana

2016-01-01

To analyze the healing of bone tissue treated with Er:YAG laser contact and noncontact modes of and piezosurgery in a rat model using triangular laser profilometry. Twenty-four 10-week-old adult male Wistar rats were used in the study. Three osteotomies on the medial part of tibia were performed in each animal, 1 in the right tibia and 2 in the left tibia. The osteotomies were performed with a piezoelectric device set at maximal power and the Er:YAG laser in contact mode (power, 7.5 W; pulse energy, 375 mJ; repetition rate, 20 Hz; MSP mode) and noncontact mode (power, 7.5 W; pulse energy, 750 mJ; repetition rate, 10 Hz; QSP mode) with a novel type of circular, digitally controlled handpiece (x-Runner). After surgery, 6 animals were immediately euthanized (group 1), and the others were euthanized after 1 week (group 2, n = 6), 2 weeks (group 3, n = 6), and 3 weeks (group 4, n = 6). Bone healing after osteotomy was analyzed using a 3-dimensional laser scanning technique (ie, laser triangulation profilometry). The volume reduction rates are similar for all 3 techniques (0.2 to 0.25 mm(3) per week). Greater volume reduction of 0.25 mm3 per week was observed for the Er:YAG laser in noncontact mode (x-Runner). After 3 weeks, almost complete healing of the prepared osteotomy was observed. Within the limitations of this study, the osteotomies performed by the Er:YAG laser in digitally controlled noncontact mode healed the fastest. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Incorporation of a laser range scanner into image-guided liver surgery: surface acquisition, registration, and tracking.

PubMed

Cash, David M; Sinha, Tuhin K; Chapman, William C; Terawaki, Hiromi; Dawant, Benoit M; Galloway, Robert L; Miga, Michael I

2003-07-01

As image guided surgical procedures become increasingly diverse, there will be more scenarios where point-based fiducials cannot be accurately localized for registration and rigid body assumptions no longer hold. As a result, procedures will rely more frequently on anatomical surfaces for the basis of image alignment and will require intraoperative geometric data to measure and compensate for tissue deformation in the organ. In this paper we outline methods for which a laser range scanner may be used to accomplish these tasks intraoperatively. A laser range scanner based on the optical principle of triangulation acquires a dense set of three-dimensional point data in a very rapid, noncontact fashion. Phantom studies were performed to test the ability to link range scan data with traditional modes of image-guided surgery data through localization, registration, and tracking in physical space. The experiments demonstrate that the scanner is capable of localizing point-based fiducials to within 0.2 mm and capable of achieving point and surface based registrations with target registration error of less than 2.0 mm. Tracking points in physical space with the range scanning system yields an error of 1.4 +/- 0.8 mm. Surface deformation studies were performed with the range scanner in order to determine if this device was capable of acquiring enough information for compensation algorithms. In the surface deformation studies, the range scanner was able to detect changes in surface shape due to deformation comparable to those detected by tomographic image studies. Use of the range scanner has been approved for clinical trials, and an initial intraoperative range scan experiment is presented. In all of these studies, the primary source of error in range scan data is deterministically related to the position and orientation of the surface within the scanner's field of view. However, this systematic error can be corrected, allowing the range scanner to provide a rapid, robust method of acquiring anatomical surfaces intraoperatively.

Ranging bowhead whale calls in a shallow-water dispersive waveguide.

PubMed

Abadi, Shima H; Thode, Aaron M; Blackwell, Susanna B; Dowling, David R

2014-07-01

This paper presents the performance of three methods for estimating the range of broadband (50-500 Hz) bowhead whale calls in a nominally 55-m-deep waveguide: Conventional mode filtering (CMF), synthetic time reversal (STR), and triangulation. The first two methods use a linear vertical array to exploit dispersive propagation effects in the underwater sound channel. The triangulation technique used here, while requiring no knowledge about the propagation environment, relies on a distributed array of directional autonomous seafloor acoustics recorders (DASARs) arranged in triangular grid with 7 km spacing. This study uses simulations and acoustic data collected in 2010 from coastal waters near Kaktovik, Alaska. At that time, a 12-element vertical array, spanning the bottom 63% of the water column, was deployed alongside a distributed array of seven DASARs. The estimated call location-to-array ranges determined from CMF and STR are compared with DASAR triangulation results for 19 whale calls. The vertical-array ranging results are generally within ±10% of the DASAR results with the STR results providing slightly better agreement. The results also indicate that the vertical array can range calls over larger ranges and with greater precision than the particular distributed array discussed here, whenever the call locations are beyond the distributed array boundaries.

3D measurement using circular gratings

NASA Astrophysics Data System (ADS)

Harding, Kevin

2013-09-01

3D measurement using methods of structured light are well known in the industry. Most such systems use some variation of straight lines, either as simple lines or with some form of encoding. This geometry assumes the lines will be projected from one side and viewed from another to generate the profile information. But what about applications where a wide triangulation angle may not be practical, particularly at longer standoff distances. This paper explores the use of circular grating patterns projected from a center point to achieve 3D information. Originally suggested by John Caulfield around 1990, the method had some interesting potential, particularly if combined with alternate means of measurement from traditional triangulation including depth from focus methods. The possible advantages of a central reference point in the projected pattern may offer some different capabilities not as easily attained with a linear grating pattern. This paper will explore the pros and cons of the method and present some examples of possible applications.

A Mixed Methods Portrait of Urban Instrumental Music Teaching

ERIC Educational Resources Information Center

Fitzpatrick, Kate R.

2011-01-01

The purpose of this mixed methods study was to learn about the ways that instrumental music teachers in Chicago navigated the urban landscape. The design of the study most closely resembles Creswell and Plano Clark's (2007) two-part Triangulation Convergence Mixed Methods Design, with the addition of an initial exploratory focus group component.…

A Multimodal Deep Log-Based User Experience (UX) Platform for UX Evaluation

PubMed Central

Ali Khan, Wajahat; Hur, Taeho; Muhammad Bilal, Hafiz Syed; Ul Hassan, Anees; Lee, Sungyoung

2018-01-01

The user experience (UX) is an emerging field in user research and design, and the development of UX evaluation methods presents a challenge for both researchers and practitioners. Different UX evaluation methods have been developed to extract accurate UX data. Among UX evaluation methods, the mixed-method approach of triangulation has gained importance. It provides more accurate and precise information about the user while interacting with the product. However, this approach requires skilled UX researchers and developers to integrate multiple devices, synchronize them, analyze the data, and ultimately produce an informed decision. In this paper, a method and system for measuring the overall UX over time using a triangulation method are proposed. The proposed platform incorporates observational and physiological measurements in addition to traditional ones. The platform reduces the subjective bias and validates the user’s perceptions, which are measured by different sensors through objectification of the subjective nature of the user in the UX assessment. The platform additionally offers plug-and-play support for different devices and powerful analytics for obtaining insight on the UX in terms of multiple participants. PMID:29783712

A Multimodal Deep Log-Based User Experience (UX) Platform for UX Evaluation.

PubMed

Hussain, Jamil; Khan, Wajahat Ali; Hur, Taeho; Bilal, Hafiz Syed Muhammad; Bang, Jaehun; Hassan, Anees Ul; Afzal, Muhammad; Lee, Sungyoung

2018-05-18

The user experience (UX) is an emerging field in user research and design, and the development of UX evaluation methods presents a challenge for both researchers and practitioners. Different UX evaluation methods have been developed to extract accurate UX data. Among UX evaluation methods, the mixed-method approach of triangulation has gained importance. It provides more accurate and precise information about the user while interacting with the product. However, this approach requires skilled UX researchers and developers to integrate multiple devices, synchronize them, analyze the data, and ultimately produce an informed decision. In this paper, a method and system for measuring the overall UX over time using a triangulation method are proposed. The proposed platform incorporates observational and physiological measurements in addition to traditional ones. The platform reduces the subjective bias and validates the user's perceptions, which are measured by different sensors through objectification of the subjective nature of the user in the UX assessment. The platform additionally offers plug-and-play support for different devices and powerful analytics for obtaining insight on the UX in terms of multiple participants.

3D laser measurements of bare and shod feet during walking.

PubMed

Novak, Boštjan; Možina, Janez; Jezeršek, Matija

2014-01-01

This article presents a new system for 3D foot-shape measurements during walking. It is based on the laser-triangulation, multiple-line-illumination and color-modulation techniques. It consists of a walking stage and four measuring modules that simultaneously acquire the foot shape from the top, bottom and side views. The measuring speed is 30 fps. Custom-developed software makes it possible to analyze the foot's dimensions at an arbitrary cross-section by means of the width, height, girth and section orientation. Six subjects were measured during bare and shod walking, and the bare foot and the outside dimensions of the footwear during the entire stance phase are presented. The relative measurement repeatability of a single subject is 0.5% for bare foot and 1% for shod foot. This means that it is possible to study the differences between various influences on the foot-shape dynamics, such as a bare/shod foot, different loading conditions and the shoe's stiffness condition. Copyright © 2014 Elsevier B.V. All rights reserved.

Recent advances in laser triangulation-based measurement of airfoil surfaces

NASA Astrophysics Data System (ADS)

Hageniers, Omer L.

1995-01-01

The measurement of aircraft jet engine turbine and compressor blades requires a high degree of accuracy. This paper will address the development and performance attributes of a noncontact electro-optical gaging system specifically designed to meet the airfoil dimensional measurement requirements inherent in turbine and compressor blade manufacture and repair. The system described consists of the following key components: a high accuracy, dual channel, laser based optical sensor, a four degree of freedom mechanical manipulator system and a computer based operator interface. Measurement modes of the system include point by point data gathering at rates up to 3 points per second and an 'on-the-fly' mode where points can be gathered at data rates up to 20 points per second at surface scanning speeds of up to 1 inch per second. Overall system accuracy is +/- 0.0005 inches in a configuration that is useable in the blade manufacturing area. The systems ability to input design data from CAD data bases and output measurement data in a CAD compatible data format is discussed.

Fast and low-cost structured light pattern sequence projection.

PubMed

Wissmann, Patrick; Forster, Frank; Schmitt, Robert

2011-11-21

We present a high-speed and low-cost approach for structured light pattern sequence projection. Using a fast rotating binary spatial light modulator, our method is potentially capable of projection frequencies in the kHz domain, while enabling pattern rasterization as low as 2 μm pixel size and inherently linear grayscale reproduction quantized at 12 bits/pixel or better. Due to the circular arrangement of the projected fringe patterns, we extend the widely used ray-plane triangulation method to ray-cone triangulation and provide a detailed description of the optical calibration procedure. Using the proposed projection concept in conjunction with the recently published coded phase shift (CPS) pattern sequence, we demonstrate high accuracy 3-D measurement at 200 Hz projection frequency and 20 Hz 3-D reconstruction rate. © 2011 Optical Society of America

Reconstruction of measurable three-dimensional point cloud model based on large-scene archaeological excavation sites

NASA Astrophysics Data System (ADS)

Zhang, Chun-Sen; Zhang, Meng-Meng; Zhang, Wei-Xing

2017-01-01

This paper outlines a low-cost, user-friendly photogrammetric technique with nonmetric cameras to obtain excavation site digital sequence images, based on photogrammetry and computer vision. Digital camera calibration, automatic aerial triangulation, image feature extraction, image sequence matching, and dense digital differential rectification are used, combined with a certain number of global control points of the excavation site, to reconstruct the high precision of measured three-dimensional (3-D) models. Using the acrobatic figurines in the Qin Shi Huang mausoleum excavation as an example, our method solves the problems of little base-to-height ratio, high inclination, unstable altitudes, and significant ground elevation changes affecting image matching. Compared to 3-D laser scanning, the 3-D color point cloud obtained by this method can maintain the same visual result and has advantages of low project cost, simple data processing, and high accuracy. Structure-from-motion (SfM) is often used to reconstruct 3-D models of large scenes and has lower accuracy if it is a reconstructed 3-D model of a small scene at close range. Results indicate that this method quickly achieves 3-D reconstruction of large archaeological sites and produces heritage site distribution of orthophotos providing a scientific basis for accurate location of cultural relics, archaeological excavations, investigation, and site protection planning. This proposed method has a comprehensive application value.

3D interferometric shape measurement technique using coherent fiber bundles

NASA Astrophysics Data System (ADS)

Zhang, Hao; Kuschmierz, Robert; Czarske, Jürgen

2017-06-01

In-situ 3-D shape measurements with submicron shape uncertainty of fast rotating objects in a cutting lathe are expected, which can be achieved by simultaneous distance and velocity measurements. Conventional tactile methods, coordinate measurement machines, only support ex-situ measurements. Optical measurement techniques such as triangulation and conoscopic holography offer only the distance, so that the absolute diameter cannot be retrieved directly. In comparison, laser Doppler distance sensors (P-LDD sensor) enable simultaneous and in-situ distance and velocity measurements for monitoring the cutting process in a lathe. In order to achieve shape measurement uncertainties below 1 μm, a P-LDD sensor with a dual camera based scattered light detection has been investigated. Coherent fiber bundles (CFB) are employed to forward the scattered light towards cameras. This enables a compact and passive sensor head in the future. Compared with a photo detector based sensor, the dual camera based sensor allows to decrease the measurement uncertainty by the order of one magnitude. As a result, the total shape uncertainty of absolute 3-D shape measurements can be reduced to about 100 nm.

Triangulation Processes Experienced by Children in Contemporary China

ERIC Educational Resources Information Center

Wang, Meiping; Liu, Siwei; Belsky, Jay

2017-01-01

Most family-system research on triangulation processes has been undertaken in the West, with little known about this family dynamic in the East. The present cross-sectional study analysed 1,073 Chinese 3rd-12th-graders' self-reported exposure to three kinds of triangulation--cross-generation coalition, scapegoating, and parentification--in…

Profiles of Cognitive Appraisals and Triangulation into Interparental Conflict: Implications for Adolescent Adjustment

PubMed Central

Fosco, Gregory M.; Bray, Bethany C.

2016-01-01

Youth appraisals and triangulation into conflicts are key mechanisms by which interparental conflict places youth at risk for psychological maladjustment. Although evidence suggests that there are multiple mechanisms at work (e.g., Fosco & Feinberg, 2015; Grych, Harold, & Miles, 2003), this body of work has relied on variable-centered analyses that are limited to the unique contributions of each process to the variance in outcomes. In reality, it is possible that different combinations of these risk mechanisms may account for multifinality in risk outcomes. Using latent profile analysis (LPA) we examined profiles of threat appraisals, self-blaming attributions, and triangulation in relation to internalizing and externalizing problems in a sample of 285, ethnically diverse high school students. The current analyses revealed five distinct profiles of appraisals and triangulation, including an overall low-risk group and a global high-risk group, in which all three processes were below average or above average, respectively. Additional profiles included combinations of threat and blame, threat and triangulation, and blame and triangulation. Links between these profiles and emotional distress, problem behavior, and academic outcomes are discussed. PMID:26963695

Triangulation-based 3D surveying borescope

NASA Astrophysics Data System (ADS)

Pulwer, S.; Steglich, P.; Villringer, C.; Bauer, J.; Burger, M.; Franz, M.; Grieshober, K.; Wirth, F.; Blondeau, J.; Rautenberg, J.; Mouti, S.; Schrader, S.

2016-04-01

In this work, a measurement concept based on triangulation was developed for borescopic 3D-surveying of surface defects. The integration of such measurement system into a borescope environment requires excellent space utilization. The triangulation angle, the projected pattern, the numerical apertures of the optical system, and the viewing angle were calculated using partial coherence imaging and geometric optical raytracing methods. Additionally, optical aberrations and defocus were considered by the integration of Zernike polynomial coefficients. The measurement system is able to measure objects with a size of 50 μm in all dimensions with an accuracy of +/- 5 μm. To manage the issue of a low depth of field while using an optical high resolution system, a wavelength dependent aperture was integrated. Thereby, we are able to control depth of field and resolution of the optical system and can use the borescope in measurement mode with high resolution and low depth of field or in inspection mode with low resolution and higher depth of field. First measurements of a demonstrator system are in good agreement with our simulations.

Behavioral Changes Based on a Course in Agroecology: A Mixed Methods Study

ERIC Educational Resources Information Center

Harms, Kristyn; King, James; Francis, Charles

2009-01-01

This study evaluated and described student perceptions of a course in agroecology to determine if participants experienced changed perceptions and behaviors resulting from the Agroecosystems Analysis course. A triangulation validating quantitative data mixed methods approach included a written survey comprised of both quantitative and open-ended…

A RUTCOR Project in Discrete Applied Mathematics

DTIC Science & Technology

1990-02-20

representations of smooth piecewise polynomial functions over triangulated regions have led in particular to the conclusion that Groebner basis methods of...Reversing Number of a Digraph," in preparation. 4. Billera, L.J., and Rose, L.L., " Groebner Basis Methods for Multivariate Splines," RRR 1-89, January

Class Jumping into Academia: Multiple Identities for Counseling Academics

ERIC Educational Resources Information Center

Nelson, Mary Lee; Englar-Carlson, Matt; Tierney, Sandra C.; Hau, Julie M.

2006-01-01

Eleven counseling psychology and counselor education academics were interviewed regarding their experiences of progressing from lower-or lower-middle-class backgrounds to college and, further, to academic positions. Grounded theory method was used for data analysis, and consensual qualitative research methods were used for triangulation and data…

Combining qualitative and quantitative research within mixed method research designs: a methodological review.

PubMed

Östlund, Ulrika; Kidd, Lisa; Wengström, Yvonne; Rowa-Dewar, Neneh

2011-03-01

It has been argued that mixed methods research can be useful in nursing and health science because of the complexity of the phenomena studied. However, the integration of qualitative and quantitative approaches continues to be one of much debate and there is a need for a rigorous framework for designing and interpreting mixed methods research. This paper explores the analytical approaches (i.e. parallel, concurrent or sequential) used in mixed methods studies within healthcare and exemplifies the use of triangulation as a methodological metaphor for drawing inferences from qualitative and quantitative findings originating from such analyses. This review of the literature used systematic principles in searching CINAHL, Medline and PsycINFO for healthcare research studies which employed a mixed methods approach and were published in the English language between January 1999 and September 2009. In total, 168 studies were included in the results. Most studies originated in the United States of America (USA), the United Kingdom (UK) and Canada. The analytic approach most widely used was parallel data analysis. A number of studies used sequential data analysis; far fewer studies employed concurrent data analysis. Very few of these studies clearly articulated the purpose for using a mixed methods design. The use of the methodological metaphor of triangulation on convergent, complementary, and divergent results from mixed methods studies is exemplified and an example of developing theory from such data is provided. A trend for conducting parallel data analysis on quantitative and qualitative data in mixed methods healthcare research has been identified in the studies included in this review. Using triangulation as a methodological metaphor can facilitate the integration of qualitative and quantitative findings, help researchers to clarify their theoretical propositions and the basis of their results. This can offer a better understanding of the links between theory and empirical findings, challenge theoretical assumptions and develop new theory. Copyright © 2010 Elsevier Ltd. All rights reserved.

Large N Limits in Tensor Models: Towards More Universality Classes of Colored Triangulations in Dimension d≥2

NASA Astrophysics Data System (ADS)

Bonzom, Valentin

2016-07-01

We review an approach which aims at studying discrete (pseudo-)manifolds in dimension d≥ 2 and called random tensor models. More specifically, we insist on generalizing the two-dimensional notion of p-angulations to higher dimensions. To do so, we consider families of triangulations built out of simplices with colored faces. Those simplices can be glued to form new building blocks, called bubbles which are pseudo-manifolds with boundaries. Bubbles can in turn be glued together to form triangulations. The main challenge is to classify the triangulations built from a given set of bubbles with respect to their numbers of bubbles and simplices of codimension two. While the colored triangulations which maximize the number of simplices of codimension two at fixed number of simplices are series-parallel objects called melonic triangulations, this is not always true anymore when restricting attention to colored triangulations built from specific bubbles. This opens up the possibility of new universality classes of colored triangulations. We present three existing strategies to find those universality classes. The first two strategies consist in building new bubbles from old ones for which the problem can be solved. The third strategy is a bijection between those colored triangulations and stuffed, edge-colored maps, which are some sort of hypermaps whose hyperedges are replaced with edge-colored maps. We then show that the present approach can lead to enumeration results and identification of universality classes, by working out the example of quartic tensor models. They feature a tree-like phase, a planar phase similar to two-dimensional quantum gravity and a phase transition between them which is interpreted as a proliferation of baby universes. While this work is written in the context of random tensors, it is almost exclusively of combinatorial nature and we hope it is accessible to interested readers who are not familiar with random matrices, tensors and quantum field theory.

A Mixed-Methods Analysis in Assessing Students' Professional Development by Applying an Assessment for Learning Approach.

PubMed

Peeters, Michael J; Vaidya, Varun A

2016-06-25

Objective. To describe an approach for assessing the Accreditation Council for Pharmacy Education's (ACPE) doctor of pharmacy (PharmD) Standard 4.4, which focuses on students' professional development. Methods. This investigation used mixed methods with triangulation of qualitative and quantitative data to assess professional development. Qualitative data came from an electronic developmental portfolio of professionalism and ethics, completed by PharmD students during their didactic studies. Quantitative confirmation came from the Defining Issues Test (DIT)-an assessment of pharmacists' professional development. Results. Qualitatively, students' development reflections described growth through this course series. Quantitatively, the 2015 PharmD class's DIT N2-scores illustrated positive development overall; the lower 50% had a large initial improvement compared to the upper 50%. Subsequently, the 2016 PharmD class confirmed these average initial improvements of students and also showed further substantial development among students thereafter. Conclusion. Applying an assessment for learning approach, triangulation of qualitative and quantitative assessments confirmed that PharmD students developed professionally during this course series.

Quadtree of TIN: a new algorithm of dynamic LOD

NASA Astrophysics Data System (ADS)

Zhang, Junfeng; Fei, Lifan; Chen, Zhen

2009-10-01

Currently, Real-time visualization of large-scale digital elevation model mainly employs the regular structure of GRID based on quadtree and triangle simplification methods based on irregular triangulated network (TIN). TIN is a refined means to express the terrain surface in the computer science, compared with GRID. However, the data structure of TIN model is complex, and is difficult to realize view-dependence representation of level of detail (LOD) quickly. GRID is a simple method to realize the LOD of terrain, but contains more triangle count. A new algorithm, which takes full advantage of the two methods' merit, is presented in this paper. This algorithm combines TIN with quadtree structure to realize the view-dependence LOD controlling over the irregular sampling point sets, and holds the details through the distance of viewpoint and the geometric error of terrain. Experiments indicate that this approach can generate an efficient quadtree triangulation hierarchy over any irregular sampling point sets and achieve dynamic and visual multi-resolution performance of large-scale terrain at real-time.

Automated matching of corresponding seed images of three simulator radiographs to allow 3D triangulation of implanted seeds.

PubMed

Altschuler, M D; Kassaee, A

1997-02-01

To match corresponding seed images in different radiographs so that the 3D seed locations can be triangulated automatically and without ambiguity requires (at least) three radiographs taken from different perspectives, and an algorithm that finds the proper permutations of the seed-image indices. Matching corresponding images in only two radiographs introduces inherent ambiguities which can be resolved only with the use of non-positional information obtained with intensive human effort. Matching images in three or more radiographs is an 'NP (Non-determinant in Polynomial time)-complete' problem. Although the matching problem is fundamental, current methods for three-radiograph seed-image matching use 'local' (seed-by-seed) methods that may lead to incorrect matchings. We describe a permutation-sampling method which not only gives good 'global' (full permutation) matches for the NP-complete three-radiograph seed-matching problem, but also determines the reliability of the radiographic data themselves, namely, whether the patient moved in the interval between radiographic perspectives.

Automated matching of corresponding seed images of three simulator radiographs to allow 3D triangulation of implanted seeds

NASA Astrophysics Data System (ADS)

Altschuler, Martin D.; Kassaee, Alireza

1997-02-01

To match corresponding seed images in different radiographs so that the 3D seed locations can be triangulated automatically and without ambiguity requires (at least) three radiographs taken from different perspectives, and an algorithm that finds the proper permutations of the seed-image indices. Matching corresponding images in only two radiographs introduces inherent ambiguities which can be resolved only with the use of non-positional information obtained with intensive human effort. Matching images in three or more radiographs is an `NP (Non-determinant in Polynomial time)-complete' problem. Although the matching problem is fundamental, current methods for three-radiograph seed-image matching use `local' (seed-by-seed) methods that may lead to incorrect matchings. We describe a permutation-sampling method which not only gives good `global' (full permutation) matches for the NP-complete three-radiograph seed-matching problem, but also determines the reliability of the radiographic data themselves, namely, whether the patient moved in the interval between radiographic perspectives.

Automatic Generation of CFD-Ready Surface Triangulations from CAD Geometry

NASA Technical Reports Server (NTRS)

Aftosmis, M. J.; Delanaye, M.; Haimes, R.; Nixon, David (Technical Monitor)

1998-01-01

This paper presents an approach for the generation of closed manifold surface triangulations from CAD geometry. CAD parts and assemblies are used in their native format, without translation, and a part's native geometry engine is accessed through a modeler-independent application programming interface (API). In seeking a robust and fully automated procedure, the algorithm is based on a new physical space manifold triangulation technique which was developed to avoid robustness issues associated with poorly conditioned mappings. In addition, this approach avoids the usual ambiguities associated with floating-point predicate evaluation on constructed coordinate geometry in a mapped space, The technique is incremental, so that each new site improves the triangulation by some well defined quality measure. Sites are inserted using a variety of priority queues to ensure that new insertions will address the worst triangles first, As a result of this strategy, the algorithm will return its 'best' mesh for a given (prespecified) number of sites. Alternatively, the algorithm may be allowed to terminate naturally after achieving a prespecified measure of mesh quality. The resulting triangulations are 'CFD-ready' in that: (1) Edges match the underlying part model to within a specified tolerance. (2) Triangles on disjoint surfaces in close proximity have matching length-scales. (3) The algorithm produces a triangulation such that no angle is less than a given angle bound, alpha, or greater than Pi - 2alpha This result also sets bounds on the maximum vertex degree, triangle aspect-ratio and maximum stretching rate for the triangulation. In addition to tile output triangulations for a variety of CAD parts, tile discussion presents related theoretical results which assert the existence of such all angle bound, and demonstrate that maximum bounds of between 25 deg and 30 deg may be achieved in practice.

Accuracy Assessment of a Canal-Tunnel 3d Model by Comparing Photogrammetry and Laserscanning Recording Techniques

NASA Astrophysics Data System (ADS)

Charbonnier, P.; Chavant, P.; Foucher, P.; Muzet, V.; Prybyla, D.; Perrin, T.; Grussenmeyer, P.; Guillemin, S.

2013-07-01

With recent developments in the field of technology and computer science, conventional methods are being supplanted by laser scanning and digital photogrammetry. These two different surveying techniques generate 3-D models of real world objects or structures. In this paper, we consider the application of terrestrial Laser scanning (TLS) and photogrammetry to the surveying of canal tunnels. The inspection of such structures requires time, safe access, specific processing and professional operators. Therefore, a French partnership proposes to develop a dedicated equipment based on image processing for visual inspection of canal tunnels. A 3D model of the vault and side walls of the tunnel is constructed from images recorded onboard a boat moving inside the tunnel. To assess the accuracy of this photogrammetric model (PM), a reference model is build using static TLS. We here address the problem comparing the resulting point clouds. Difficulties arise because of the highly differentiated acquisition processes, which result in very different point densities. We propose a new tool, designed to compare differences between pairs of point cloud or surfaces (triangulated meshes). Moreover, dealing with huge datasets requires the implementation of appropriate structures and algorithms. Several techniques are presented : point-to-point, cloud-to-cloud and cloud-to-mesh. In addition farthest point resampling, octree structure and Hausdorff distance are adopted and described. Experimental results are shown for a 475 m long canal tunnel located in France.

Efficient content-based low-altitude images correlated network and strips reconstruction

NASA Astrophysics Data System (ADS)

He, Haiqing; You, Qi; Chen, Xiaoyong

2017-01-01

The manual intervention method is widely used to reconstruct strips for further aerial triangulation in low-altitude photogrammetry. Clearly the method for fully automatic photogrammetric data processing is not an expected way. In this paper, we explore a content-based approach without manual intervention or external information for strips reconstruction. Feature descriptors in the local spatial patterns are extracted by SIFT to construct vocabulary tree, in which these features are encoded in terms of TF-IDF numerical statistical algorithm to generate new representation for each low-altitude image. Then images correlated network is reconstructed by similarity measure, image matching and geometric graph theory. Finally, strips are reconstructed automatically by tracing straight lines and growing adjacent images gradually. Experimental results show that the proposed approach is highly effective in automatically rearranging strips of lowaltitude images and can provide rough relative orientation for further aerial triangulation.

Discrepancies between qualitative and quantitative evaluation of randomised controlled trial results: achieving clarity through mixed methods triangulation.

PubMed

Tonkin-Crine, Sarah; Anthierens, Sibyl; Hood, Kerenza; Yardley, Lucy; Cals, Jochen W L; Francis, Nick A; Coenen, Samuel; van der Velden, Alike W; Godycki-Cwirko, Maciek; Llor, Carl; Butler, Chris C; Verheij, Theo J M; Goossens, Herman; Little, Paul

2016-05-12

Mixed methods are commonly used in health services research; however, data are not often integrated to explore complementarity of findings. A triangulation protocol is one approach to integrating such data. A retrospective triangulation protocol was carried out on mixed methods data collected as part of a process evaluation of a trial. The multi-country randomised controlled trial found that a web-based training in communication skills (including use of a patient booklet) and the use of a C-reactive protein (CRP) point-of-care test decreased antibiotic prescribing by general practitioners (GPs) for acute cough. The process evaluation investigated GPs' and patients' experiences of taking part in the trial. Three analysts independently compared findings across four data sets: qualitative data collected view semi-structured interviews with (1) 62 patients and (2) 66 GPs and quantitative data collected via questionnaires with (3) 2886 patients and (4) 346 GPs. Pairwise comparisons were made between data sets and were categorised as agreement, partial agreement, dissonance or silence. Three instances of dissonance occurred in 39 independent findings. GPs and patients reported different views on the use of a CRP test. GPs felt that the test was useful in convincing patients to accept a no-antibiotic decision, but patient data suggested that this was unnecessary if a full explanation was given. Whilst qualitative data indicated all patients were generally satisfied with their consultation, quantitative data indicated highest levels of satisfaction for those receiving a detailed explanation from their GP with a booklet giving advice on self-care. Both qualitative and quantitative data sets indicated higher patient enablement for those in the communication groups who had received a booklet. Use of CRP tests does not appear to engage patients or influence illness perceptions and its effect is more centred on changing clinician behaviour. Communication skills and the patient booklet were relevant and useful for all patients and associated with increased patient satisfaction. A triangulation protocol to integrate qualitative and quantitative data can reveal findings that need further interpretation and also highlight areas of dissonance that lead to a deeper insight than separate analyses.

Determination of Shift/Bias in Digital Aerial Triangulation of UAV Imagery Sequences

NASA Astrophysics Data System (ADS)

Wierzbicki, Damian

2017-12-01

Currently UAV Photogrammetry is characterized a largely automated and efficient data processing. Depicting from the low altitude more often gains on the meaning in the uses of applications as: cities mapping, corridor mapping, road and pipeline inspections or mapping of large areas e.g. forests. Additionally, high-resolution video image (HD and bigger) is more often use for depicting from the low altitude from one side it lets deliver a lot of details and characteristics of ground surfaces features, and from the other side is presenting new challenges in the data processing. Therefore, determination of elements of external orientation plays a substantial role the detail of Digital Terrain Models and artefact-free ortophoto generation. Parallel a research on the quality of acquired images from UAV and above the quality of products e.g. orthophotos are conducted. Despite so fast development UAV photogrammetry still exists the necessity of accomplishment Automatic Aerial Triangulation (AAT) on the basis of the observations GPS/INS and via ground control points. During low altitude photogrammetric flight, the approximate elements of external orientation registered by UAV are burdened with the influence of some shift/bias errors. In this article, methods of determination shift/bias error are presented. In the process of the digital aerial triangulation two solutions are applied. In the first method shift/bias error was determined together with the drift/bias error, elements of external orientation and coordinates of ground control points. In the second method shift/bias error was determined together with the elements of external orientation, coordinates of ground control points and drift/bias error equals 0. When two methods were compared the difference for shift/bias error is more than ±0.01 m for all terrain coordinates XYZ.

A general and Robust Ray-Casting-Based Algorithm for Triangulating Surfaces at the Nanoscale

PubMed Central

Decherchi, Sergio; Rocchia, Walter

2013-01-01

We present a general, robust, and efficient ray-casting-based approach to triangulating complex manifold surfaces arising in the nano-bioscience field. This feature is inserted in a more extended framework that: i) builds the molecular surface of nanometric systems according to several existing definitions, ii) can import external meshes, iii) performs accurate surface area estimation, iv) performs volume estimation, cavity detection, and conditional volume filling, and v) can color the points of a grid according to their locations with respect to the given surface. We implemented our methods in the publicly available NanoShaper software suite (www.electrostaticszone.eu). Robustness is achieved using the CGAL library and an ad hoc ray-casting technique. Our approach can deal with any manifold surface (including nonmolecular ones). Those explicitly treated here are the Connolly-Richards (SES), the Skin, and the Gaussian surfaces. Test results indicate that it is robust to rotation, scale, and atom displacement. This last aspect is evidenced by cavity detection of the highly symmetric structure of fullerene, which fails when attempted by MSMS and has problems in EDTSurf. In terms of timings, NanoShaper builds the Skin surface three times faster than the single threaded version in Lindow et al. on a 100,000 atoms protein and triangulates it at least ten times more rapidly than the Kruithof algorithm. NanoShaper was integrated with the DelPhi Poisson-Boltzmann equation solver. Its SES grid coloring outperformed the DelPhi counterpart. To test the viability of our method on large systems, we chose one of the biggest molecular structures in the Protein Data Bank, namely the 1VSZ entry, which corresponds to the human adenovirus (180,000 atoms after Hydrogen addition). We were able to triangulate the corresponding SES and Skin surfaces (6.2 and 7.0 million triangles, respectively, at a scale of 2 grids per Å) on a middle-range workstation. PMID:23577073

Understanding Succession Planning and Management Efforts at Midwestern University: A Mixed Methods Study

ERIC Educational Resources Information Center

Mateso, Peter E. E.

2010-01-01

The purpose of this concurrent triangulation mixed methods study was to understand the status of succession planning and management (SPM) efforts of the subject university as perceived by the fulltime academic and fulltime administrative staff. Four research questions guided this study: (1) how do fulltime academic staff and fulltime…

The Importance of Using Games in EFL Classrooms

ERIC Educational Resources Information Center

Gozcu, Emine; Caganaga, Cagda Kivanc

2016-01-01

This paper aims to find out how games are important and effective when used in EFL classrooms. Two different kinds of qualitative research methods: semi-structured interviews and observation were conducted in this study. Multi-method triangulation is used throughout the study. The data was carried out through audio-recorded interview and…

Hobby-Related Information-Seeking Behaviour of Highly Dedicated Online Museum Visitors

ERIC Educational Resources Information Center

Skov, Mette

2013-01-01

Introduction: This paper explores the characteristics of online museum visitors in an everyday life, information-seeking context. Method: A triangulation of research methods was applied. A Web questionnaire survey gave initial, quantitative information about online museum visitors to a military museum. Follow-up interviews (n = 24) obtained rich,…

A fuzzy pattern matching method based on graph kernel for lithography hotspot detection

NASA Astrophysics Data System (ADS)

Nitta, Izumi; Kanazawa, Yuzi; Ishida, Tsutomu; Banno, Koji

2017-03-01

In advanced technology nodes, lithography hotspot detection has become one of the most significant issues in design for manufacturability. Recently, machine learning based lithography hotspot detection has been widely investigated, but it has trade-off between detection accuracy and false alarm. To apply machine learning based technique to the physical verification phase, designers require minimizing undetected hotspots to avoid yield degradation. They also need a ranking of similar known patterns with a detected hotspot to prioritize layout pattern to be corrected. To achieve high detection accuracy and to prioritize detected hotspots, we propose a novel lithography hotspot detection method using Delaunay triangulation and graph kernel based machine learning. Delaunay triangulation extracts features of hotspot patterns where polygons locate irregularly and closely one another, and graph kernel expresses inner structure of graphs. Additionally, our method provides similarity between two patterns and creates a list of similar training patterns with a detected hotspot. Experiments results on ICCAD 2012 benchmarks show that our method achieves high accuracy with allowable range of false alarm. We also show the ranking of the similar known patterns with a detected hotspot.

A constrained Delaunay discretization method for adaptively meshing highly discontinuous geological media

NASA Astrophysics Data System (ADS)

Wang, Yang; Ma, Guowei; Ren, Feng; Li, Tuo

2017-12-01

A constrained Delaunay discretization method is developed to generate high-quality doubly adaptive meshes of highly discontinuous geological media. Complex features such as three-dimensional discrete fracture networks (DFNs), tunnels, shafts, slopes, boreholes, water curtains, and drainage systems are taken into account in the mesh generation. The constrained Delaunay triangulation method is used to create adaptive triangular elements on planar fractures. Persson's algorithm (Persson, 2005), based on an analogy between triangular elements and spring networks, is enriched to automatically discretize a planar fracture into mesh points with varying density and smooth-quality gradient. The triangulated planar fractures are treated as planar straight-line graphs (PSLGs) to construct piecewise-linear complex (PLC) for constrained Delaunay tetrahedralization. This guarantees the doubly adaptive characteristic of the resulted mesh: the mesh is adaptive not only along fractures but also in space. The quality of elements is compared with the results from an existing method. It is verified that the present method can generate smoother elements and a better distribution of element aspect ratios. Two numerical simulations are implemented to demonstrate that the present method can be applied to various simulations of complex geological media that contain a large number of discontinuities.

Endoscopic laser range scanner for minimally invasive, image guided kidney surgery

NASA Astrophysics Data System (ADS)

Friets, Eric; Bieszczad, Jerry; Kynor, David; Norris, James; Davis, Brynmor; Allen, Lindsay; Chambers, Robert; Wolf, Jacob; Glisson, Courtenay; Herrell, S. Duke; Galloway, Robert L.

2013-03-01

Image guided surgery (IGS) has led to significant advances in surgical procedures and outcomes. Endoscopic IGS is hindered, however, by the lack of suitable intraoperative scanning technology for registration with preoperative tomographic image data. This paper describes implementation of an endoscopic laser range scanner (eLRS) system for accurate, intraoperative mapping of the kidney surface, registration of the measured kidney surface with preoperative tomographic images, and interactive image-based surgical guidance for subsurface lesion targeting. The eLRS comprises a standard stereo endoscope coupled to a steerable laser, which scans a laser fan beam across the kidney surface, and a high-speed color camera, which records the laser-illuminated pixel locations on the kidney. Through calibrated triangulation, a dense set of 3-D surface coordinates are determined. At maximum resolution, the eLRS acquires over 300,000 surface points in less than 15 seconds. Lower resolution scans of 27,500 points are acquired in one second. Measurement accuracy of the eLRS, determined through scanning of reference planar and spherical phantoms, is estimated to be 0.38 +/- 0.27 mm at a range of 2 to 6 cm. Registration of the scanned kidney surface with preoperative image data is achieved using a modified iterative closest point algorithm. Surgical guidance is provided through graphical overlay of the boundaries of subsurface lesions, vasculature, ducts, and other renal structures labeled in the CT or MR images, onto the eLRS camera image. Depth to these subsurface targets is also displayed. Proof of clinical feasibility has been established in an explanted perfused porcine kidney experiment.

Processing Motion: Using Code to Teach Newtonian Physics

NASA Astrophysics Data System (ADS)

Massey, M. Ryan

Prior to instruction, students often possess a common-sense view of motion, which is inconsistent with Newtonian physics. Effective physics lessons therefore involve conceptual change. To provide a theoretical explanation for concepts and how they change, the triangulation model brings together key attributes of prototypes, exemplars, theories, Bayesian learning, ontological categories, and the causal model theory. The triangulation model provides a theoretical rationale for why coding is a viable method for physics instruction. As an experiment, thirty-two adolescent students participated in summer coding academies to learn how to design Newtonian simulations. Conceptual and attitudinal data was collected using the Force Concept Inventory and the Colorado Learning Attitudes about Science Survey. Results suggest that coding is an effective means for teaching Newtonian physics.

Stereo-tomography in triangulated models

NASA Astrophysics Data System (ADS)

Yang, Kai; Shao, Wei-Dong; Xing, Feng-yuan; Xiong, Kai

2018-04-01

Stereo-tomography is a distinctive tomographic method. It is capable of estimating the scatterer position, the local dip of scatterer and the background velocity simultaneously. Building a geologically consistent velocity model is always appealing for applied and earthquake seismologists. Differing from the previous work to incorporate various regularization techniques into the cost function of stereo-tomography, we think extending stereo-tomography to the triangulated model will be the most straightforward way to achieve this goal. In this paper, we provided all the Fréchet derivatives of stereo-tomographic data components with respect to model components for slowness-squared triangulated model (or sloth model) in 2D Cartesian coordinate based on the ray perturbation theory for interfaces. A sloth model representation means a sparser model representation when compared with conventional B-spline model representation. A sparser model representation leads to a smaller scale of stereo-tomographic (Fréchet) matrix, a higher-accuracy solution when solving linear equations, a faster convergence rate and a lower requirement for quantity of data space. Moreover, a quantitative representation of interface strengthens the relationships among different model components, which makes the cross regularizations among these model components, such as node coordinates, scatterer coordinates and scattering angles, etc., more straightforward and easier to be implemented. The sensitivity analysis, the model resolution matrix analysis and a series of synthetic data examples demonstrate the correctness of the Fréchet derivatives, the applicability of the regularization terms and the robustness of the stereo-tomography in triangulated model. It provides a solid theoretical foundation for the real applications in the future.

Measuring teamwork in primary care: Triangulation of qualitative and quantitative data.

PubMed

Brown, Judith Belle; Ryan, Bridget L; Thorpe, Cathy; Markle, Emma K R; Hutchison, Brian; Glazier, Richard H

2015-09-01

This article describes the triangulation of qualitative dimensions, reflecting high functioning teams, with the results of standardized teamwork measures. The study used a mixed methods design using qualitative and quantitative approaches to assess teamwork in 19 Family Health Teams in Ontario, Canada. This article describes dimensions from the qualitative phase using grounded theory to explore the issues and challenges to teamwork. Two quantitative measures were used in the study, the Team Climate Inventory (TCI) and the Providing Effective Resources and Knowledge (PERK) scale. For the triangulation analysis, the mean scores of these measures were compared with the qualitatively derived ratings for the dimensions. The final sample for the qualitative component was 107 participants. The qualitative analysis identified 9 dimensions related to high team functioning such as common philosophy, scope of practice, conflict resolution, change management, leadership, and team evolution. From these dimensions, teams were categorized numerically as high, moderate, or low functioning. Three hundred seventeen team members completed the survey measures. Mean site scores for the TCI and PERK were 3.87 and 3.88, respectively (of 5). The TCI was associated will all dimensions except for team location, space allocation, and executive director leadership. The PERK was associated with all dimensions except team location. Data triangulation provided qualitative and quantitative evidence of what constitutes teamwork. Leadership was pivotal in forging a common philosophy and encouraging team collaboration. Teams used conflict resolution strategies and adapted to the changes they encountered. These dimensions advanced the team's evolution toward a high functioning team. (c) 2015 APA, all rights reserved).

Stochastic Surface Mesh Reconstruction

NASA Astrophysics Data System (ADS)

Ozendi, M.; Akca, D.; Topan, H.

2018-05-01

A generic and practical methodology is presented for 3D surface mesh reconstruction from the terrestrial laser scanner (TLS) derived point clouds. It has two main steps. The first step deals with developing an anisotropic point error model, which is capable of computing the theoretical precisions of 3D coordinates of each individual point in the point cloud. The magnitude and direction of the errors are represented in the form of error ellipsoids. The following second step is focused on the stochastic surface mesh reconstruction. It exploits the previously determined error ellipsoids by computing a point-wise quality measure, which takes into account the semi-diagonal axis length of the error ellipsoid. The points only with the least errors are used in the surface triangulation. The remaining ones are automatically discarded.

Structured Light-Based Hazard Detection For Planetary Surface Navigation

NASA Technical Reports Server (NTRS)

Nefian, Ara; Wong, Uland Y.; Dille, Michael; Bouyssounouse, Xavier; Edwards, Laurence; To, Vinh; Deans, Matthew; Fong, Terry

2017-01-01

This paper describes a structured light-based sensor for hazard avoidance in planetary environments. The system presented here can also be used in terrestrial applications constrained by reduced onboard power and computational complexity and low illumination conditions. The sensor is on a calibrated camera and laser dot projector system. The onboard hazard avoidance system determines the position of the projected dots in the image and through a triangulation process detects potential hazards. The paper presents the design parameters for this sensor and describes the image based solution for hazard avoidance. The system presented here was tested extensively in day and night conditions in Lunar analogue environments. The current system achieves over 97 detection rate with 1.7 false alarms over 2000 images.

On triangulations of the plane by pencils of conics. II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazareva, V B; Shelekhov, A M

2013-06-30

The present work continues our previous paper in which all possible triangulations of the plane using three pencils of circles were listed. In the present article we find all projectively distinct triangulations of the plane by pencils of conics that are obtained by projecting regular three-webs, cut out on a nondegenerate cubic surface by three pencils of planes, whose axes lie on this surface. Bibliography: 6 titles.

Rockfall hazard assessment of nearly vertical rhyolite tuff cliff faces by using terrestrial laser scanner, UAV and FEM analyses

NASA Astrophysics Data System (ADS)

Török, Ákos; Barsi, Árpád; Görög, Péter; Lovas, Tamás; Bögöly, Gyula; Czinder, Balázs; Vásárhelyi, Balázs; Molnár, Bence; József Somogyi, Árpád

2017-04-01

Nearly vertical rhyolite tuff cliff faces are located in NE-Hungary representing rock fall hazard in the touristic region of Sirok. Larger blocks of the cliff have fallen in recent years menacing tourists and human lives. The rhyolite tuff, that forms the Castle Hill was formed during Miocene volcanism and comprises of brecciated lapilli tuffs and tuffs with intercalating ignimbritic horizons. The paper focuses on the 3D mapping of cliff faces and modeling of rock fall hazard. The topography and 3D model of the cliff was obtained by using GNSS supported terrestrial laser scanner and UAV. With imaging techniques of UAV a Triangulated Irregular Network (TIN) model was developed that contained triangles with 5-10 cm side lengths. GNSS supported terrestrial laser scanning allowed the observation with a resolution 1-5 cm of point spacing. The point clouds were further processed and with the combination of laser scanner and UAV data a 3D model of the studied cliff faces were obtained. Geological parameters for rock fall analyses included both field observations and laboratory tests. The lithotypes were identified on the field and were sampled for rock mechanical laboratory analyses. Joint- and fault system was mapped and visualized by using Rocscience Dip. EN test methods were used to obtain the density properties of various lithotypes of rhyolite tuff. Other standardized EN tests included ultrasonic pulse velocity, water absorption, indirect tensile strength (Brasilian), uniaxial compressive strength and modulus of elasticity of air dry and of water saturated samples. GSI values were denoted based on filed observations and rock mass properties. The stability analyses of cliff faces were made by using 2D FEM software (Phase 2). Cross sections were evaluated and global factor of safety was also calculated. The modeled displacements were in the order of few centimeters; however several locations were pinpointed where wedge failure and planar slip surfaces were identified as major cliff stability hazards. These were associated with the major joint systems dissecting cliff faces. This research have proved that the combined methods of field surveying, imaging techniques, data processing and FEM modelling with rock mechanical laboratory analyses allowed the identification of major rock fall hazards even at areas which are difficult to access.

Understanding the Effects of Time on Collaborative Learning Processes in Problem Based Learning: A Mixed Methods Study

ERIC Educational Resources Information Center

Hommes, J.; Van den Bossche, P.; de Grave, W.; Bos, G.; Schuwirth, L.; Scherpbier, A.

2014-01-01

Little is known how time influences collaborative learning groups in medical education. Therefore a thorough exploration of the development of learning processes over time was undertaken in an undergraduate PBL curriculum over 18 months. A mixed-methods triangulation design was used. First, the quantitative study measured how various learning…

An Examination of Rater Performance on a Local Oral English Proficiency Test: A Mixed-Methods Approach

ERIC Educational Resources Information Center

Yan, Xun

2014-01-01

This paper reports on a mixed-methods approach to evaluate rater performance on a local oral English proficiency test. Three types of reliability estimates were reported to examine rater performance from different perspectives. Quantitative results were also triangulated with qualitative rater comments to arrive at a more representative picture of…

Metrological analysis of the human foot: 3D multisensor exploration

NASA Astrophysics Data System (ADS)

Muñoz Potosi, A.; Meneses Fonseca, J.; León Téllez, J.

2011-08-01

In the podiatry field, many of the foot dysfunctions are mainly generated due to: Congenital malformations, accidents or misuse of footwear. For the treatment or prevention of foot disorders, the podiatrist diagnoses prosthesis or specific adapted footwear, according to the real dimension of foot. Therefore, it is necessary to acquire 3D information of foot with 360 degrees of observation. As alternative solution, it was developed and implemented an optical system of threedimensional reconstruction based in the principle of laser triangulation. The system is constituted by an illumination unit that project a laser plane into the foot surface, an acquisition unit with 4 CCD cameras placed around of axial foot axis, an axial moving unit that displaces the illumination and acquisition units in the axial axis direction and a processing and exploration unit. The exploration software allows the extraction of distances on three-dimensional image, taking into account the topography of foot. The optical system was tested and their metrological performances were evaluated in experimental conditions. The optical system was developed to acquire 3D information in order to design and make more appropriate footwear.

Realist explanatory theory building method for social epidemiology: a protocol for a mixed method multilevel study of neighbourhood context and postnatal depression.

PubMed

Eastwood, John G; Jalaludin, Bin B; Kemp, Lynn A

2014-01-01

A recent criticism of social epidemiological studies, and multi-level studies in particular has been a paucity of theory. We will present here the protocol for a study that aims to build a theory of the social epidemiology of maternal depression. We use a critical realist approach which is trans-disciplinary, encompassing both quantitative and qualitative traditions, and that assumes both ontological and hierarchical stratification of reality. We describe a critical realist Explanatory Theory Building Method comprising of an: 1) emergent phase, 2) construction phase, and 3) confirmatory phase. A concurrent triangulated mixed method multilevel cross-sectional study design is described. The Emergent Phase uses: interviews, focus groups, exploratory data analysis, exploratory factor analysis, regression, and multilevel Bayesian spatial data analysis to detect and describe phenomena. Abductive and retroductive reasoning will be applied to: categorical principal component analysis, exploratory factor analysis, regression, coding of concepts and categories, constant comparative analysis, drawing of conceptual networks, and situational analysis to generate theoretical concepts. The Theory Construction Phase will include: 1) defining stratified levels; 2) analytic resolution; 3) abductive reasoning; 4) comparative analysis (triangulation); 5) retroduction; 6) postulate and proposition development; 7) comparison and assessment of theories; and 8) conceptual frameworks and model development. The strength of the critical realist methodology described is the extent to which this paradigm is able to support the epistemological, ontological, axiological, methodological and rhetorical positions of both quantitative and qualitative research in the field of social epidemiology. The extensive multilevel Bayesian studies, intensive qualitative studies, latent variable theory, abductive triangulation, and Inference to Best Explanation provide a strong foundation for Theory Construction. The study will contribute to defining the role that realism and mixed methods can play in explaining the social determinants and developmental origins of health and disease.

Realist theory construction for a mixed method multilevel study of neighbourhood context and postnatal depression.

PubMed

Eastwood, John G; Kemp, Lynn A; Jalaludin, Bin B

2016-01-01

We have recently described a protocol for a study that aims to build a theory of neighbourhood context and postnatal depression. That protocol proposed a critical realist Explanatory Theory Building Method comprising of an: (1) emergent phase, (2) construction phase, and (3) confirmatory phase. A concurrent triangulated mixed method multilevel cross-sectional study design was described. The protocol also described in detail the Theory Construction Phase which will be presented here. The Theory Construction Phase will include: (1) defining stratified levels; (2) analytic resolution; (3) abductive reasoning; (4) comparative analysis (triangulation); (5) retroduction; (6) postulate and proposition development; (7) comparison and assessment of theories; and (8) conceptual frameworks and model development. The stratified levels of analysis in this study were predominantly social and psychological. The abductive analysis used the theoretical frames of: Stress Process; Social Isolation; Social Exclusion; Social Services; Social Capital, Acculturation Theory and Global-economic level mechanisms. Realist propositions are presented for each analysis of triangulated data. Inference to best explanation is used to assess and compare theories. A conceptual framework of maternal depression, stress and context is presented that includes examples of mechanisms at psychological, social, cultural and global-economic levels. Stress was identified as a necessary mechanism that has the tendency to cause several outcomes including depression, anxiety, and health harming behaviours. The conceptual framework subsequently included conditional mechanisms identified through the retroduction including the stressors of isolation and expectations and buffers of social support and trust. The meta-theory of critical realism is used here to generate and construct social epidemiological theory using stratified ontology and both abductive and retroductive analysis. The findings will be applied to the development of a middle range theory and subsequent programme theory for local perinatal child and family interventions.

Beta-function B-spline smoothing on triangulations

NASA Astrophysics Data System (ADS)

Dechevsky, Lubomir T.; Zanaty, Peter

2013-03-01

In this work we investigate a novel family of Ck-smooth rational basis functions on triangulations for fitting, smoothing, and denoising geometric data. The introduced basis function is closely related to a recently introduced general method introduced in utilizing generalized expo-rational B-splines, which provides Ck-smooth convex resolutions of unity on very general disjoint partitions and overlapping covers of multidimensional domains with complex geometry. One of the major advantages of this new triangular construction is its locality with respect to the star-1 neighborhood of the vertex on which the said base is providing Hermite interpolation. This locality of the basis functions can be in turn utilized in adaptive methods, where, for instance a local refinement of the underlying triangular mesh affects only the refined domain, whereas, in other method one needs to investigate what changes are occurring outside of the refined domain. Both the triangular and the general smooth constructions have the potential to become a new versatile tool of Computer Aided Geometric Design (CAGD), Finite and Boundary Element Analysis (FEA/BEA) and Iso-geometric Analysis (IGA).

On the Use of CAD-Native Predicates and Geometry in Surface Meshing

NASA Technical Reports Server (NTRS)

Aftosmis, M. J.

1999-01-01

Several paradigms for accessing CAD geometry during surface meshing for CFD are discussed. File translation, inconsistent geometry engines and non-native point construction are all identified as sources of non-robustness. The paper argues in favor of accessing CAD parts and assemblies in their native format, without translation, and for the use of CAD-native predicates and constructors in surface mesh generation. The discussion also emphasizes the importance of examining the computational requirements for exact evaluation of triangulation predicates during surface meshing. The native approach is demonstrated through an algorithm for the generation of closed manifold surface triangulations from CAD geometry. CAD parts and assemblies are used in their native format, and a part's native geometry engine is accessed through a modeler-independent application programming interface (API). In seeking a robust and fully automated procedure, the algorithm is based on a new physical space manifold triangulation technique specially developed to avoid robustness issues associated with poorly conditioned mappings. In addition, this approach avoids the usual ambiguities associated with floating-point predicate evaluation on constructed coordinate geometry in a mapped space. The technique is incremental, so that each new site improves the triangulation by some well defined quality measure. The algorithm terminates after achieving a prespecified measure of mesh quality and produces a triangulation such that no angle is less than a given angle bound, a or greater than pi - 2alpha. This result also sets bounds on the maximum vertex degree, triangle aspect-ratio and maximum stretching rate for the triangulation. In addition to the output triangulations for a variety of CAD parts, the discussion presents related theoretical results which assert the existence of such an angle bound, and demonstrate that maximum bounds of between 25 deg and 30 deg may be achieved in practice.

Family processes that shape the impact of interparental conflict on adolescents.

PubMed

Grych, John H; Raynor, Sarah R; Fosco, Gregory M

2004-01-01

This study draws on the family systems concepts of triangulation and wholism to investigate how interparental conflict may affect adolescents' psychological adjustment. An ethnically and socioeconomically diverse sample (N = 388) of 14- to 18-year-olds completed measures of interparental conflict, family relationships, internalizing problems, and externalizing problems. We found that triangulation into parental disagreements mediated the association between parental conflict and both internalizing and externalizing problems. Adolescents exposed to more frequent, intense, and poorly resolved conflict were more likely to feel triangulated, but this association was moderated by the nature of the alliances they had with their parents. Specifically, at low levels of interparental conflict, adolescents who had substantially stronger alliances with one parent than the other reported greater triangulation than those with more balanced alliances. At high levels of conflict, these groups reported similar degrees of triangulation. We also found that supportive parent-child relationships reduced adolescents' appraisals of threat and self-blame for interparental conflict, while more empathic relationships with siblings increased these appraisals. Finally, close relationships with fathers acted as a protective factor that reduced symptoms of maladjustment.

Understanding Black Male Student Athletes' Experiences at a Historically Black College/University: A Mixed Methods Approach

ERIC Educational Resources Information Center

Cooper, Joseph N.; Hall, Jori

2016-01-01

The purpose of this article is to describe how a mixed methods approach was employed to acquire a better understanding of Black male student athletes' experiences at a historically Black college/university in the southeastern United States. A concurrent triangulation design was incorporated to allow different data sources to be collected and…

Utilizing field-aligned current profiles derived from Swarm to estimate the peak emission height of 630 nm auroral arcs: a comparison of methods and discussion of associated error estimates in the ASI data.

NASA Astrophysics Data System (ADS)

Gillies, D. M.; Knudsen, D. J.; Donovan, E.; Jackel, B. J.; Gillies, R.; Spanswick, E.

2017-12-01

We compare field-aligned currents (FACs) measured by the Swarm constellation of satellites with the location of red-line (630 nm) auroral arcs observed by all-sky imagers (ASIs) to derive a characteristic emission height for the optical emissions. In our 10 events we find that an altitude of 200 km applied to the ASI maps gives optimal agreement between the two observations. We also compare the new FAC method against the traditional triangulation method using pairs of all-sky imagers (ASIs), and against electron density profiles obtained from the Resolute Bay Incoherent Scatter Radar-Canadian radar (RISR-C), both of which are consistent with a characteristic emission height of 200 km. We also present the spatial error associated with georeferencing REdline Geospace Observatory (REGO) and THEMIS all-sky imagers (ASIs) and how it applies to altitude projections of the mapped image. Utilizing this error we validate the estimated altitude of redline aurora using two methods: triangulation between ASIs and field-aligned current profiles derived from magnetometers on-board the Swarm satellites.

Three-dimensional unstructured grid generation via incremental insertion and local optimization

NASA Technical Reports Server (NTRS)

Barth, Timothy J.; Wiltberger, N. Lyn; Gandhi, Amar S.

1992-01-01

Algorithms for the generation of 3D unstructured surface and volume grids are discussed. These algorithms are based on incremental insertion and local optimization. The present algorithms are very general and permit local grid optimization based on various measures of grid quality. This is very important; unlike the 2D Delaunay triangulation, the 3D Delaunay triangulation appears not to have a lexicographic characterization of angularity. (The Delaunay triangulation is known to minimize that maximum containment sphere, but unfortunately this is not true lexicographically). Consequently, Delaunay triangulations in three-space can result in poorly shaped tetrahedral elements. Using the present algorithms, 3D meshes can be constructed which optimize a certain angle measure, albeit locally. We also discuss the combinatorial aspects of the algorithm as well as implementational details.

Conoscopic holography for image registration: a feasibility study

NASA Astrophysics Data System (ADS)

Lathrop, Ray A.; Cheng, Tiffany T.; Webster, Robert J., III

2009-02-01

Preoperative image data can facilitate intrasurgical guidance by revealing interior features of opaque tissues, provided image data can be accurately registered to the physical patient. Registration is challenging in organs that are deformable and lack features suitable for use as alignment fiducials (e.g. liver, kidneys, etc.). However, provided intraoperative sensing of surface contours can be accomplished, a variety of rigid and deformable 3D surface registration techniques become applicable. In this paper, we evaluate the feasibility of conoscopic holography as a new method to sense organ surface shape. We also describe potential advantages of conoscopic holography, including the promise of replacing open surgery with a laparoscopic approach. Our feasibility study investigated use of a tracked off-the-shelf conoscopic holography unit to perform a surface scans on several types of biological and synthetic phantom tissues. After first exploring baseline accuracy and repeatability of distance measurements, we performed a number of surface scan experiments on the phantom and ex vivo tissues with a variety of surface properties and shapes. These indicate that conoscopic holography is capable of generating surface point clouds of at least comparable (and perhaps eventually improved) accuracy in comparison to published experimental laser triangulation-based surface scanning results.

Acquisition of Real-Time Operation Analytics for an Automated Serial Sectioning System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madison, Jonathan D.; Underwood, O. D.; Poulter, Gregory A.

Mechanical serial sectioning is a highly repetitive technique employed in metallography for the rendering of 3D reconstructions of microstructure. While alternate techniques such as ultrasonic detection, micro-computed tomography, and focused ion beam milling have progressed much in recent years, few alternatives provide equivalent opportunities for comparatively high resolutions over significantly sized cross-sectional areas and volumes. To that end, the introduction of automated serial sectioning systems has greatly heightened repeatability and increased data collection rates while diminishing opportunity for mishandling and other user-introduced errors. Unfortunately, even among current, state-of-the-art automated serial sectioning systems, challenges in data collection have not been fullymore » eradicated. Therefore, this paper highlights two specific advances to assist in this area; a non-contact laser triangulation method for assessment of material removal rates and a newly developed graphical user interface providing real-time monitoring of experimental progress. Furthermore, both are shown to be helpful in the rapid identification of anomalies and interruptions, while also providing comparable and less error-prone measures of removal rate over the course of these long-term, challenging, and innately destructive characterization experiments.« less

Representation and Reconconstruction of Triangular Irregular Networks with Vertical Walls

NASA Astrophysics Data System (ADS)

Gorte, B.; Lesparre, J.

2012-06-01

Point clouds obtained by aerial laser scanning are a convenient input source for high resolution 2.5d elevation models, such as the Dutch AHN-2. More challenging is the fully automatic reconstruction of 3d city models. An actual demand for a combined 2.5d terrain and 3d city model for an urban hydrology application led to the design of an extension to the well-known Delaunay triangulated irregular networks (TINs) as to accommodate vertical walls. In addition we introduce methods to generate and refine models adhering to our data structure. These are based on combining two approaches: a representation of the TIN using stars of vertices and triangles, together with segmenting the TIN on the basis of coplanarity of adjacent triangles. The approach is supposed to deliver the complete model including walls at the correct locations, without relying on additional map data, as these often lack completeness, actuality and accuracy, and moreover most of the time do not account for parts facades not going down to street level. However, automatic detection of height discontinuities to obtain the exact location of the walls is currently still under implementation.

Acquisition of Real-Time Operation Analytics for an Automated Serial Sectioning System

DOE PAGES

Madison, Jonathan D.; Underwood, O. D.; Poulter, Gregory A.; ...

2017-03-22

Mechanical serial sectioning is a highly repetitive technique employed in metallography for the rendering of 3D reconstructions of microstructure. While alternate techniques such as ultrasonic detection, micro-computed tomography, and focused ion beam milling have progressed much in recent years, few alternatives provide equivalent opportunities for comparatively high resolutions over significantly sized cross-sectional areas and volumes. To that end, the introduction of automated serial sectioning systems has greatly heightened repeatability and increased data collection rates while diminishing opportunity for mishandling and other user-introduced errors. Unfortunately, even among current, state-of-the-art automated serial sectioning systems, challenges in data collection have not been fullymore » eradicated. Therefore, this paper highlights two specific advances to assist in this area; a non-contact laser triangulation method for assessment of material removal rates and a newly developed graphical user interface providing real-time monitoring of experimental progress. Furthermore, both are shown to be helpful in the rapid identification of anomalies and interruptions, while also providing comparable and less error-prone measures of removal rate over the course of these long-term, challenging, and innately destructive characterization experiments.« less

Near-UV laser treatment of extrinsic dental enamel stains.

PubMed

Schoenly, J E; Seka, W; Featherstone, J D B; Rechmann, P

2012-04-01

The selective ablation of extrinsic dental enamel stains using a 400-nm laser is evaluated at several fluences for completely removing stains with minimal damage to the underlying enamel. A frequency-doubled Ti:sapphire laser (400-nm wavelength, 60-nanosecond pulse duration, 10-Hz repetition rate) was used to treat 10 extracted human teeth with extrinsic enamel staining. Each tooth was irradiated perpendicular to the surface in a back-and-forth motion over a 1-mm length using an ∼300-µm-diam 10th-order super-Gaussian beam with fluences ranging from 0.8 to 6.4 J/cm(2) . Laser triangulation determined stain depth and volume removed by measuring 3D surface images before and after irradiation. Scanning electron microscopy evaluated the surface roughness of enamel following stain removal. Fluorescence spectroscopy measured spectra of unbleached and photobleached stains in the spectral range of 600-800 nm. Extrinsic enamel stains are removed with laser fluences between 0.8 and 6.4 J/cm(2) . Stains removed on sound enamel leave behind a smooth enamel surface. Stain removal in areas with signs of earlier cariogenic acid attacks resulted in isolated and randomly located laser-induced, 50-µm-diam enamel pits. These pits contain 0.5-µm diam, smooth craters indicative of heat transfer from the stain to the enamel and subsequent melting and water droplet ejection. Ablation stalling of enamel stains is typically observed at low fluences (<3 J/cm(2) ) and is accompanied by a drastic reduction in porphyrin fluorescence from the Soret band. Laser ablation of extrinsic enamel stains at 400 nm is observed to be most efficient above 3 J/cm(2) with minimal damage to the underlying enamel. Unsound underlying enamel is also observed to be selectively removed after irradiation. Copyright © 2012 Wiley Periodicals, Inc.

A Discontinuous Galerkin Finite Element Method for Hamilton-Jacobi Equations

NASA Technical Reports Server (NTRS)

Hu, Changqing; Shu, Chi-Wang

1998-01-01

In this paper, we present a discontinuous Galerkin finite element method for solving the nonlinear Hamilton-Jacobi equations. This method is based on the Runge-Kutta discontinuous Galerkin finite element method for solving conservation laws. The method has the flexibility of treating complicated geometry by using arbitrary triangulation, can achieve high order accuracy with a local, compact stencil, and are suited for efficient parallel implementation. One and two dimensional numerical examples are given to illustrate the capability of the method.

Enhancing Breast Cancer Recurrence Algorithms Through Selective Use of Medical Record Data.

PubMed

Kroenke, Candyce H; Chubak, Jessica; Johnson, Lisa; Castillo, Adrienne; Weltzien, Erin; Caan, Bette J

2016-03-01

The utility of data-based algorithms in research has been questioned because of errors in identification of cancer recurrences. We adapted previously published breast cancer recurrence algorithms, selectively using medical record (MR) data to improve classification. We evaluated second breast cancer event (SBCE) and recurrence-specific algorithms previously published by Chubak and colleagues in 1535 women from the Life After Cancer Epidemiology (LACE) and 225 women from the Women's Health Initiative cohorts and compared classification statistics to published values. We also sought to improve classification with minimal MR examination. We selected pairs of algorithms-one with high sensitivity/high positive predictive value (PPV) and another with high specificity/high PPV-using MR information to resolve discrepancies between algorithms, properly classifying events based on review; we called this "triangulation." Finally, in LACE, we compared associations between breast cancer survival risk factors and recurrence using MR data, single Chubak algorithms, and triangulation. The SBCE algorithms performed well in identifying SBCE and recurrences. Recurrence-specific algorithms performed more poorly than published except for the high-specificity/high-PPV algorithm, which performed well. The triangulation method (sensitivity = 81.3%, specificity = 99.7%, PPV = 98.1%, NPV = 96.5%) improved recurrence classification over two single algorithms (sensitivity = 57.1%, specificity = 95.5%, PPV = 71.3%, NPV = 91.9%; and sensitivity = 74.6%, specificity = 97.3%, PPV = 84.7%, NPV = 95.1%), with 10.6% MR review. Triangulation performed well in survival risk factor analyses vs analyses using MR-identified recurrences. Use of multiple recurrence algorithms in administrative data, in combination with selective examination of MR data, may improve recurrence data quality and reduce research costs. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

The application of GPS precise point positioning technology in aerial triangulation

NASA Astrophysics Data System (ADS)

Yuan, Xiuxiao; Fu, Jianhong; Sun, Hongxing; Toth, Charles

In traditional GPS-supported aerotriangulation, differential GPS (DGPS) positioning technology is used to determine the 3-dimensional coordinates of the perspective centers at exposure time with an accuracy of centimeter to decimeter level. This method can significantly reduce the number of ground control points (GCPs). However, the establishment of GPS reference stations for DGPS positioning is not only labor-intensive and costly, but also increases the implementation difficulty of aerial photography. This paper proposes aerial triangulation supported with GPS precise point positioning (PPP) as a way to avoid the use of the GPS reference stations and simplify the work of aerial photography. Firstly, we present the algorithm for GPS PPP in aerial triangulation applications. Secondly, the error law of the coordinate of perspective centers determined using GPS PPP is analyzed. Thirdly, based on GPS PPP and aerial triangulation software self-developed by the authors, four sets of actual aerial images taken from surveying and mapping projects, different in both terrain and photographic scale, are given as experimental models. The four sets of actual data were taken over a flat region at a scale of 1:2500, a mountainous region at a scale of 1:3000, a high mountainous region at a scale of 1:32000 and an upland region at a scale of 1:60000 respectively. In these experiments, the GPS PPP results were compared with results obtained through DGPS positioning and traditional bundle block adjustment. In this way, the empirical positioning accuracy of GPS PPP in aerial triangulation can be estimated. Finally, the results of bundle block adjustment with airborne GPS controls from GPS PPP are analyzed in detail. The empirical results show that GPS PPP applied in aerial triangulation has a systematic error of half-meter level and a stochastic error within a few decimeters. However, if a suitable adjustment solution is adopted, the systematic error can be eliminated in GPS-supported bundle block adjustment. When four full GCPs are emplaced in the corners of the adjustment block, then the systematic error is compensated using a set of independent unknown parameters for each strip, the final result of the bundle block adjustment with airborne GPS controls from PPP is the same as that of bundle block adjustment with airborne GPS controls from DGPS. Although the accuracy of the former is a little lower than that of traditional bundle block adjustment with dense GCPs, it can still satisfy the accuracy requirement of photogrammetric point determination for topographic mapping at many scales.

Digital dental surface registration with laser scanner for orthodontics set-up planning

NASA Astrophysics Data System (ADS)

Alcaniz-Raya, Mariano L.; Albalat, Salvador E.; Grau Colomer, Vincente; Monserrat, Carlos A.

1997-05-01

We present an optical measuring system based on laser structured light suitable for its diary use in orthodontics clinics that fit four main requirements: (1) to avoid use of stone models, (2) to automatically discriminate geometric points belonging to teeth and gum, (3) to automatically calculate diagnostic parameters used by orthodontists, (4) to make use of low cost and easy to use technology for future commercial use. Proposed technique is based in the use of hydrocolloids mould used by orthodontists for stone model obtention. These mould of the inside of patient's mouth are composed of very fluent materials like alginate or hydrocolloids that reveal fine details of dental anatomy. Alginate mould are both very easy to obtain and very low costly. Once captured, alginate moulds are digitized by mean of a newly developed and patented 3D dental scanner. Developed scanner is based in the optical triangulation method based in the projection of a laser line on the alginate mould surface. Line deformation gives uncalibrated shape information. Relative linear movements of the mould with respect to the sensor head gives more sections thus obtaining a full 3D uncalibrated dentition model. Developed device makes use of redundant CCD in the sensor head and servocontrolled linear axis for mould movement. Last step is calibration to get a real and precise X, Y, Z image. All the process is done automatically. The scanner has been specially adapted for 3D dental anatomy capturing in order to fulfill specific requirements such as: scanning time, accuracy, security and correct acquisition of 'hidden points' in alginate mould. Measurement realized on phantoms with known geometry quite similar to dental anatomy present errors less than 0,1 mm. Scanning of global dental anatomy is 2 minutes, and generation of 3D graphics of dental cast takes approximately 30 seconds in a Pentium-based PC.

Workshop on "New Engineering Technology Transfer in Orthopaedic Surgery".

DTIC Science & Technology

1999-04-01

anatomy is required to remain oriented to the tunnel -view of the arthroscope as is the ability to triangulate the instruments through proprioception...required. Methods: Eight limbs from fresh, whole cadavers were used. Motion data were collected with the OPTOTRAK infrared motion analysis system

The A+ Schools Program and School Improvement

ERIC Educational Resources Information Center

Moyer, Ashley Suzanne

2012-01-01

This study examined Missouri's A+ Schools Program and its impact on school improvement. Effective schools research combined with the mission learning for all provided a conceptual foundation for guiding research development. A mixed-method design allowing a triangulation of qualitative and quantitative data was applied using telephone interviews…

Effectiveness of Facebook in English Language Learning: A Case Study

ERIC Educational Resources Information Center

Faryadi, Qais

2017-01-01

The prime objective of this research was to investigate whether Facebook helped undergraduate students of Universiti Sains Islam Malaysia (USIM) improve their English language proficiency, critical thinking, comprehension skills, and motivation. A triangulation method (quantitative, qualitative, and descriptive) was employed in the investigation.…

Physician Educational Needs in Osteoporosis: An Approach to Needs Assessment.

ERIC Educational Resources Information Center

Lockyer, Jocelyn; Hanley, David; Fidler, Herta; Toews, John; Lysholm-Andrews, Elaine

1998-01-01

A literature review, focus groups (n=200), and questionnaire responses from 324 family physicians identified their learning needs related to osteoporosis. The three methods identified different learning issues, suggesting the importance of triangulation to ensure currency and relevance in continuing-education needs-assessment. (SK)

Spacecraft Leak Location Using Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Reusser, R. S.; Chimenti, D. E.; Holland, S. D.; Roberts, R. A.

2010-02-01

Guided ultrasonic waves, generated by air escaping through a small hole, have been measured with an 8×8 piezoelectric phased-array detector. Rapid location of air leaks in a spacecraft skin, caused by high-speed collisions with small objects, is essential for astronaut survival. Cross correlation of all 64 elements, one pair at a time, on a diced PZT disc combined with synthetic aperture analysis determines the dominant direction of wave propagation. The leak location is triangulated by combining data from two or more detector. To optimize the frequency band selection for the most robust direction finding, noise-field measurements of a plate with integral stiffeners have been performed using laser Doppler velocimetry. We compare optical and acoustic measurements to analyze the influence of the PZT array detector and its mechanical coupling to the plate.

Analysis of low-field isotropic vortex glass containing vortex groups in YBa2Cu3O7−x thin films visualized by scanning SQUID microscopy

PubMed Central

Wells, Frederick S.; Pan, Alexey V.; Wang, X. Renshaw; Fedoseev, Sergey A.; Hilgenkamp, Hans

2015-01-01

The glass-like vortex distribution in pulsed laser deposited YBa2Cu3O7 − x thin films is observed by scanning superconducting quantum interference device microscopy and analysed for ordering after cooling in magnetic fields significantly smaller than the Earth's field. Autocorrelation calculations on this distribution show a weak short-range positional order, while Delaunay triangulation shows a near-complete lack of orientational order. The distribution of these vortices is finally characterised as an isotropic vortex glass. Abnormally closely spaced groups of vortices, which are statistically unlikely to occur, are observed above a threshold magnetic field. The origin of these groups is discussed, but will require further investigation. PMID:25728772

What patient characteristics guide nurses' clinical judgement on pressure ulcer risk? A mixed methods study.

PubMed

Balzer, K; Kremer, L; Junghans, A; Halfens, R J G; Dassen, T; Kottner, J

2014-05-01

Nurses' clinical judgement plays a vital role in pressure ulcer risk assessment, but evidence is lacking which patient characteristics are important for nurses' perception of patients' risk exposure. To explore which patient characteristics nurses employ when assessing pressure ulcer risk without use of a risk assessment scale. Mixed methods design triangulating observational data from the control group of a quasi-experimental trial and data from semi-structured interviews with nurses. Two traumatological wards at a university hospital. Quantitative data: A consecutive sample of 106 patients matching the eligibility criteria (age ≥ 18 years, no pressure ulcers category ≥ 2 at admission and ≥ 5 days expected length of stay). Qualitative data: A purposive sample of 16 nurses. Quantitative data: Predictor variables for pressure ulcer risk were measured by study assistants at the bedside each second day. Concurrently, nurses documented their clinical judgement on patients' pressure ulcer risk by means of a 4-step global judgement scale. Bivariate correlations between predictor variables and nurses' risk estimates were established. Qualitative data: In interviews, nurses were asked to assess fictitious patients' pressure ulcer risk and to justify their risk estimates. Patient characteristics perceived as relevant for nurses' judements were thematically clustered. Triangulation: Firstly, predictors of nurses' risk estimates identified in bivariate analysis were cross-mapped with interview findings. Secondly, three models to predict nurses' risk estimates underwent multiple linear regression analysis. Nurses consider multiple patient characteristics for pressure ulcer risk assessment, but regard some conditions more important than others. Triangulation showed that these are measures reflecting patients' exposure to pressure or overall care dependency. Qualitative data furthermore indicate that nurses are likely to trade off risk-enhancing conditions against conditions perceived to be protective. Here, patients' mental capabilities like willingness to engage in one owns care seem to be particularly important. Due to missing information on these variables in the quantitative data, they could not be incorporated into triangulation. Nurses' clinical judgement draws on well-known aetiological factors, and tends to expand conditions covered by risk assessment scales. Patients' care dependency and self-care abilities seem to be core concepts for nurses' risk assessment. Copyright © 2013 Elsevier Ltd. All rights reserved.

The finite body triangulation: algorithms, subgraphs, homogeneity estimation and application.

PubMed

Carson, Cantwell G; Levine, Jonathan S

2016-09-01

The concept of a finite body Dirichlet tessellation has been extended to that of a finite body Delaunay 'triangulation' to provide a more meaningful description of the spatial distribution of nonspherical secondary phase bodies in 2- and 3-dimensional images. A finite body triangulation (FBT) consists of a network of minimum edge-to-edge distances between adjacent objects in a microstructure. From this is also obtained the characteristic object chords formed by the intersection of the object boundary with the finite body tessellation. These two sets of distances form the basis of a parsimonious homogeneity estimation. The characteristics of the spatial distribution are then evaluated with respect to the distances between objects and the distances within them. Quantitative analysis shows that more physically representative distributions can be obtained by selecting subgraphs, such as the relative neighbourhood graph and the minimum spanning tree, from the finite body tessellation. To demonstrate their potential, we apply these methods to 3-dimensional X-ray computed tomographic images of foamed cement and their 2-dimensional cross sections. The Python computer code used to estimate the FBT is made available. Other applications for the algorithm - such as porous media transport and crack-tip propagation - are also discussed. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Electronic device for endosurgical skills training (EDEST): study of reliability.

PubMed

Pagador, J B; Uson, J; Sánchez, M A; Moyano, J L; Moreno, J; Bustos, P; Mateos, J; Sánchez-Margallo, F M

2011-05-01

Minimally Invasive Surgery procedures are commonly used in many surgical practices, but surgeons need specific training models and devices due to its difficulty and complexity. In this paper, an innovative electronic device for endosurgical skills training (EDEST) is presented. A study on reliability for this device was performed. Different electronic components were used to compose this new training device. The EDEST was focused on two basic laparoscopic tasks: triangulation and coordination manoeuvres. A configuration and statistical software was developed to complement the functionality of the device. A calibration method was used to assure the proper work of the device. A total of 35 subjects (8 experts and 27 novices) were used to check the reliability of the system using the MTBF analysis. Configuration values for triangulation and coordination exercises were calculated as 0.5 s limit threshold and 800-11,000 lux range of light intensity, respectively. Zero errors in 1,050 executions (0%) for triangulation and 21 errors in 5,670 executions (0.37%) for coordination were obtained. A MTBF of 2.97 h was obtained. The results show that the reliability of the EDEST device is acceptable when used under previously defined light conditions. These results along with previous work could demonstrate that the EDEST device can help surgeons during first training stages.

Bias Reduction and Filter Convergence for Long Range Stereo

NASA Technical Reports Server (NTRS)

Sibley, Gabe; Matthies, Larry; Sukhatme, Gaurav

2005-01-01

We are concerned here with improving long range stereo by filtering image sequences. Traditionally, measurement errors from stereo camera systems have been approximated as 3-D Gaussians, where the mean is derived by triangulation and the covariance by linearized error propagation. However, there are two problems that arise when filtering such 3-D measurements. First, stereo triangulation suffers from a range dependent statistical bias; when filtering this leads to over-estimating the true range. Second, filtering 3-D measurements derived via linearized error propagation leads to apparent filter divergence; the estimator is biased to under-estimate range. To address the first issue, we examine the statistical behavior of stereo triangulation and show how to remove the bias by series expansion. The solution to the second problem is to filter with image coordinates as measurements instead of triangulated 3-D coordinates.

Photogrammetric technique for in-flight ranging of trailing vortices using entrained balloons

NASA Technical Reports Server (NTRS)

Snow, Walter L.; Burner, Alpheus W.; Goad, William K.

1989-01-01

A method for experimentally determining the radial distance of a probe aircraft from a trailing vortex is described. The method relies on photogrammetric triangulation of targets entrained in the vortex core. The theory and preliminary testing were described using laboratory mock-ups. Solid state video cameras were to provide data at 300 Hz rates. Practical methods for seeding the vortex are under separate investigation and are not addressed.

Taking Advantage of Selective Change Driven Processing for 3D Scanning

PubMed Central

Vegara, Francisco; Zuccarello, Pedro; Boluda, Jose A.; Pardo, Fernando

2013-01-01

This article deals with the application of the principles of SCD (Selective Change Driven) vision to 3D laser scanning. Two experimental sets have been implemented: one with a classical CMOS (Complementary Metal-Oxide Semiconductor) sensor, and the other one with a recently developed CMOS SCD sensor for comparative purposes, both using the technique known as Active Triangulation. An SCD sensor only delivers the pixels that have changed most, ordered by the magnitude of their change since their last readout. The 3D scanning method is based on the systematic search through the entire image to detect pixels that exceed a certain threshold, showing the SCD approach to be ideal for this application. Several experiments for both capturing strategies have been performed to try to find the limitations in high speed acquisition/processing. The classical approach is limited by the sequential array acquisition, as predicted by the Nyquist–Shannon sampling theorem, and this has been experimentally demonstrated in the case of a rotating helix. These limitations are overcome by the SCD 3D scanning prototype achieving a significantly higher performance. The aim of this article is to compare both capturing strategies in terms of performance in the time and frequency domains, so they share all the static characteristics including resolution, 3D scanning method, etc., thus yielding the same 3D reconstruction in static scenes. PMID:24084110

Comparison of conventional study model measurements and 3D digital study model measurements from laser scanned dental impressions

NASA Astrophysics Data System (ADS)

Nugrahani, F.; Jazaldi, F.; Noerhadi, N. A. I.

2017-08-01

The field of orthodontics is always evolving,and this includes the use of innovative technology. One type of orthodontic technology is the development of three-dimensional (3D) digital study models that replace conventional study models made by stone. This study aims to compare the mesio-distal teeth width, intercanine width, and intermolar width measurements between a 3D digital study model and a conventional study model. Twelve sets of upper arch dental impressions were taken from subjects with non-crowding teeth. The impressions were taken twice, once with alginate and once with polivinylsiloxane. The alginate impressions used in the conventional study model and the polivinylsiloxane impressions were scanned to obtain the 3D digital study model. Scanning was performed using a laser triangulation scanner device assembled by the School of Electrical Engineering and Informatics at the Institut Teknologi Bandung and David Laser Scan software. For the conventional model, themesio-distal width, intercanine width, and intermolar width were measured using digital calipers; in the 3D digital study model they were measured using software. There were no significant differences between the mesio-distal width, intercanine width, and intermolar width measurments between the conventional and 3D digital study models (p>0.05). Thus, measurements using 3D digital study models are as accurate as those obtained from conventional study models

Online Teaching in Networked Learning Communities: A Multi-Method Approach to Studying the Role of the Teacher

ERIC Educational Resources Information Center

De Laat, Maarten; Lally, Vic; Lipponen, Lasse; Simons, Robert-Jan

2007-01-01

The aim of this paper is to study the online teaching styles of two teachers who each tutor a networked learning community (NLC), within the same workshop. The study is undertaking empirical work using a multi-method approach in order to triangulate and contextualise our findings and enrich our understanding of the teacher participation in these…

Path integral measure and triangulation independence in discrete gravity

NASA Astrophysics Data System (ADS)

Dittrich, Bianca; Steinhaus, Sebastian

2012-02-01

A path integral measure for gravity should also preserve the fundamental symmetry of general relativity, which is diffeomorphism symmetry. In previous work, we argued that a successful implementation of this symmetry into discrete quantum gravity models would imply discretization independence. We therefore consider the requirement of triangulation independence for the measure in (linearized) Regge calculus, which is a discrete model for quantum gravity, appearing in the semi-classical limit of spin foam models. To this end we develop a technique to evaluate the linearized Regge action associated to Pachner moves in 3D and 4D and show that it has a simple, factorized structure. We succeed in finding a local measure for 3D (linearized) Regge calculus that leads to triangulation independence. This measure factor coincides with the asymptotics of the Ponzano Regge Model, a 3D spin foam model for gravity. We furthermore discuss to which extent one can find a triangulation independent measure for 4D Regge calculus and how such a measure would be related to a quantum model for 4D flat space. To this end, we also determine the dependence of classical Regge calculus on the choice of triangulation in 3D and 4D.

On Campus Activity Guide. Environmental Education.

ERIC Educational Resources Information Center

Pinellas County School Board, Clearwater, FL.

Descriptions of about 100 secondary-level activities that can be done on the school grounds are presented. Among the lessons included are a study of life in sidewalk cracks, methods of estimating animal populations, soil testing, constructing and using triangulation instruments to map the school area, and creative writing exercises. Although most…

Teaching Analytics: A Clustering and Triangulation Study of Digital Library User Data

ERIC Educational Resources Information Center

Xu, Beijie; Recker, Mimi

2012-01-01

Teachers and students increasingly enjoy unprecedented access to abundant web resources and digital libraries to enhance and enrich their classroom experiences. However, due to the distributed nature of such systems, conventional educational research methods, such as surveys and observations, provide only limited snapshots. In addition,…

Factors Affecting Middle School Students' Reading Motivation in Taiwan

ERIC Educational Resources Information Center

Huang, SuHua

2013-01-01

This study employed a triangulated mixed method to investigate reading motivation of Chinese middle school students in Taiwan. A total of 247 seventh grade students (122 boys and 125 girls) participated voluntarily by completing the Chinese Motivation for Research Questionnaire (CMRQ). Sixteen of the 247 students were purposely selected to…

Attitudinal Impact of Hybridized Writing about a Socioscientific Issue

ERIC Educational Resources Information Center

Tomas, Louisa; Ritchie, Stephen M.; Tones, Megan

2011-01-01

The development of scientifically literate citizens remains an important priority of science education; however, growing evidence of students' disenchantment with school science continues to challenge the realization of this aim. This triangulation mixed methods study investigated the learning experiences of 152 9th grade students as they…

Seeing in three dimensions: correlation and triangulation of Mars Exploration Rover imagery

NASA Technical Reports Server (NTRS)

Deen, Robert; Lorre, Jean

2005-01-01

This paper describes in detail the middle parts of the ground-based terrain derivation process: correlation, which finds matching points in the stereo pair, and triangulation, which converts those points to XYZ coordinates.

The Family System and Depressive Symptoms during the College Years: Triangulation, Parental Differential Treatment, and Sibling Warmth as Predictors.

PubMed

Ponappa, Sujata; Bartle-Haring, Suzanne; Holowacz, Eugene; Ferriby, Megan

2017-01-01

Guided by Bowen theory, we investigated the relationships between parent-child triangulation, parental differential treatment (PDT), sibling warmth, and individual depressive symptoms in a sample of 77 sibling dyads, aged 18-25 years, recruited through undergraduate classes at a U.S. public University. Results of the actor-partner interdependence models suggested that being triangulated into parental conflict was positively related to both siblings' perception of PDT; however, as one sibling felt triangulated, the other perceived reduced levels of PDT. For both siblings, the perception of higher levels of PDT was related to decreased sibling warmth and higher sibling warmth was associated with fewer depressive symptoms. The implications of these findings for research and the treatment of depression in the college-aged population are discussed. © 2016 American Association for Marriage and Family Therapy.

Numerical Schemes for the Hamilton-Jacobi and Level Set Equations on Triangulated Domains

NASA Technical Reports Server (NTRS)

Barth, Timothy J.; Sethian, James A.

1997-01-01

Borrowing from techniques developed for conservation law equations, numerical schemes which discretize the Hamilton-Jacobi (H-J), level set, and Eikonal equations on triangulated domains are presented. The first scheme is a provably monotone discretization for certain forms of the H-J equations. Unfortunately, the basic scheme lacks proper Lipschitz continuity of the numerical Hamiltonian. By employing a virtual edge flipping technique, Lipschitz continuity of the numerical flux is restored on acute triangulations. Next, schemes are introduced and developed based on the weaker concept of positive coefficient approximations for homogeneous Hamiltonians. These schemes possess a discrete maximum principle on arbitrary triangulations and naturally exhibit proper Lipschitz continuity of the numerical Hamiltonian. Finally, a class of Petrov-Galerkin approximations are considered. These schemes are stabilized via a least-squares bilinear form. The Petrov-Galerkin schemes do not possess a discrete maximum principle but generalize to high order accuracy.

Fast algorithms of constrained Delaunay triangulation and skeletonization for band images

NASA Astrophysics Data System (ADS)

Zeng, Wei; Yang, ChengLei; Meng, XiangXu; Yang, YiJun; Yang, XiuKun

2004-09-01

For the boundary polygons of band-images, a fast constrained Delaunay triangulation algorithm is presented and based on it an efficient skeletonization algorithm is designed. In the process of triangulation the characters of uniform grid structure and the band-polygons are utilized to improve the speed of computing the third vertex for one edge within its local ranges when forming a Delaunay triangle. The final skeleton of the band-image is derived after reducing each triangle to local skeleton lines according to its topology. The algorithm with a simple data structure is easy to understand and implement. Moreover, it can deal with multiply connected polygons on the fly. Experiments show that there is a nearly linear dependence between triangulation time and size of band-polygons randomly generated. Correspondingly, the skeletonization algorithm is also an improvement over the previously known results in terms of time. Some practical examples are given in the paper.

Automatic drawing for traffic marking with MMS LIDAR intensity

NASA Astrophysics Data System (ADS)

Takahashi, G.; Takeda, H.; Shimano, Y.

2014-05-01

Upgrading the database of CYBER JAPAN has been strategically promoted because the "Basic Act on Promotion of Utilization of Geographical Information", was enacted in May 2007. In particular, there is a high demand for road information that comprises a framework in this database. Therefore, road inventory mapping work has to be accurate and eliminate variation caused by individual human operators. Further, the large number of traffic markings that are periodically maintained and possibly changed require an efficient method for updating spatial data. Currently, we apply manual photogrammetry drawing for mapping traffic markings. However, this method is not sufficiently efficient in terms of the required productivity, and data variation can arise from individual operators. In contrast, Mobile Mapping Systems (MMS) and high-density Laser Imaging Detection and Ranging (LIDAR) scanners are rapidly gaining popularity. The aim in this study is to build an efficient method for automatically drawing traffic markings using MMS LIDAR data. The key idea in this method is extracting lines using a Hough transform strategically focused on changes in local reflection intensity along scan lines. However, also note that this method processes every traffic marking. In this paper, we discuss a highly accurate and non-human-operator-dependent method that applies the following steps: (1) Binarizing LIDAR points by intensity and extracting higher intensity points; (2) Generating a Triangulated Irregular Network (TIN) from higher intensity points; (3) Deleting arcs by length and generating outline polygons on the TIN; (4) Generating buffers from the outline polygons; (5) Extracting points from the buffers using the original LIDAR points; (6) Extracting local-intensity-changing points along scan lines using the extracted points; (7) Extracting lines from intensity-changing points through a Hough transform; and (8) Connecting lines to generate automated traffic marking mapping data.

A novel validation and calibration method for motion capture systems based on micro-triangulation.

PubMed

Nagymáté, Gergely; Tuchband, Tamás; Kiss, Rita M

2018-06-06

Motion capture systems are widely used to measure human kinematics. Nevertheless, users must consider system errors when evaluating their results. Most validation techniques for these systems are based on relative distance and displacement measurements. In contrast, our study aimed to analyse the absolute volume accuracy of optical motion capture systems by means of engineering surveying reference measurement of the marker coordinates (uncertainty: 0.75 mm). The method is exemplified on an 18 camera OptiTrack Flex13 motion capture system. The absolute accuracy was defined by the root mean square error (RMSE) between the coordinates measured by the camera system and by engineering surveying (micro-triangulation). The original RMSE of 1.82 mm due to scaling error was managed to be reduced to 0.77 mm while the correlation of errors to their distance from the origin reduced from 0.855 to 0.209. A simply feasible but less accurate absolute accuracy compensation method using tape measure on large distances was also tested, which resulted in similar scaling compensation compared to the surveying method or direct wand size compensation by a high precision 3D scanner. The presented validation methods can be less precise in some respects as compared to previous techniques, but they address an error type, which has not been and cannot be studied with the previous validation methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mesh Generation via Local Bisection Refinement of Triangulated Grids

DTIC Science & Technology

2015-06-01

Science and Technology Organisation DSTO–TR–3095 ABSTRACT This report provides a comprehensive implementation of an unstructured mesh generation method...and Technology Organisation 506 Lorimer St, Fishermans Bend, Victoria 3207, Australia Telephone: 1300 333 362 Facsimile: (03) 9626 7999 c© Commonwealth...their behaviour is critically linked to Maubach’s method and the data structures N and T . The top- level mesh refinement algorithm is also presented

Selective near-UV ablation of subgingival dental calculus: measurement of removal rates

NASA Astrophysics Data System (ADS)

Schoenly, J. E.; Seka, W.; Rechmann, P.

2010-02-01

A noncontact profilometer (laser triangulation) was used to measure the removal rates of subgingival dental calculus irradiated with a frequency-doubled Ti:sapphire laser (60-ns pulse duration, 400-nm wavelength, 10-Hz repetition rate, 7-mJ pulse energy). Profilometer traces before and after irradiation were used to create a removal map with 4-μm axial and 15-μm transverse resolution. Twenty-three teeth (15 with calculus and 8 pristine) were irradiated at 90° and 45° under a cooling water spray with a super-Gaussian beam (~300-μm diameter). Subgingival calculus was selectively removed at 5.6 and 4.0 J/cm2 for 90° and 45°, respecetively, within a range of rates, between 2 to 9 μm/pulse. These ablation rates were constant during these exposures. For comparison, pristine cementum irradiated for 10 min at the same peak fluence and pulse repetition rate showed only craters, 15 to 50 μm deep, corresponding to an equivalent removal rate three orders of magnitude smaller than that obtained for calculus. Pristine enamel was not removed under the same irradiation conditions.

Near-ultraviolet removal rates for subgingival dental calculus at different irradiation angles.

PubMed

Schoenly, Joshua E; Seka, Wolf D; Rechmann, Peter

2011-07-01

The laser ablation rate of subgingival dental calculus irradiated at a 400-nm-wavelength, 7.4-mJ pulse energy, and 85- and 20-deg irradiation angles is measured using laser triangulation. Three-dimensional images taken before and after irradiation create a removal map with 6-μm axial resolution. Fifteen human teeth with subgingival calculus are irradiated in vitro under a cooling water spray with an ∼300-μm-diam, tenth-order super-gaussian beam. The average subgingival calculus removal rates for irradiation at 85 and 20 deg are 11.1±3.6 and 11.5±5.9 μm∕pulse, respectively, for depth removal and 4.5±1.7×10(5) and 4.8±2.3×10(5) μm(3)∕pulse, respectively, for volume removal. The ablation rate is constant at each irradiation site but varies between sites because of the large differences in the physical and optical properties of calculus. Comparison of the average depth- and volume-removal rates does not reveal any dependence on the irradiation angle and is likely due to the surface topology of subgingival calculus samples that overshadows any expected angular dependence.

Near-ultraviolet removal rates for subgingival dental calculus at different irradiation angles

NASA Astrophysics Data System (ADS)

Schoenly, Joshua E.; Seka, Wolf D.; Rechmann, Peter

2011-07-01

The laser ablation rate of subgingival dental calculus irradiated at a 400-nm-wavelength, 7.4-mJ pulse energy, and 85- and 20-deg irradiation angles is measured using laser triangulation. Three-dimensional images taken before and after irradiation create a removal map with 6-μm axial resolution. Fifteen human teeth with subgingival calculus are irradiated in vitro under a cooling water spray with an ~300-μm-diam, tenth-order super-Gaussian beam. The average subgingival calculus removal rates for irradiation at 85 and 20 deg are 11.1+/-3.6 and 11.5+/-5.9 μm/pulse, respectively, for depth removal and 4.5+/-1.7×105 and 4.8+/-2.3×105 μm3/pulse, respectively, for volume removal. The ablation rate is constant at each irradiation site but varies between sites because of the large differences in the physical and optical properties of calculus. Comparison of the average depth- and volume-removal rates does not reveal any dependence on the irradiation angle and is likely due to the surface topology of subgingival calculus samples that overshadows any expected angular dependence.

Selective Near-UV Ablation of Subgingival Dental Calculus: Measurement of Removal Rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoenly, J.E.; Seka, W.; Rechmann, P.

A noncontact profilometer (laser triangulation) was used to measure the removal rates of subgingival dental calculus irradiated with a frequency-doubled Ti:sapphire laser (60-ns pulse duration, 400-nm wavelength, 10-Hz repetition rate, 7-mJ pulse energy). Profilometer traces before and after irradiation were used to create a removal map with 4-μm axial and 15-μm transverse resolution. Twenty-three teeth (15 with calculus and 8 pristine) were irradiated at 90° and 45° under a cooling water spray with a super-Gaussian beam (~300-μm diameter). Subgingival calculus was selectively removed at 5.6 and 4.0 J/cm2 for 90° and 45°, respecetively, within a range of rates, between 2more » to 9 μm/pulse. These ablation rates were constant during these exposures. For comparison, pristine cementum irradiated for 10 min at the same peak fluence and pulse repetition rate showed only craters, 15 to 50 μm deep, corresponding to an equivalent removal rate three orders of magnitude smaller than that obtained for calculus. Pristine enamel was not removed under the same irradiation conditions.« less

Occultation and Triangulation Camera (OcTriCam) Cubesat

NASA Astrophysics Data System (ADS)

Batchelor, D. A.

2018-02-01

A camera at Earth-Moon L2 would provide a 240,000 km triangulation baseline to augment near-Earth object observations with Earth-based telescopes such as Pan-STARRS, and planetary occultation research to refine ephemerides and probe ring systems.

A tour about existence and uniqueness of dg enhancements and lifts

NASA Astrophysics Data System (ADS)

Canonaco, Alberto; Stellari, Paolo

2017-12-01

This paper surveys the recent advances concerning the relations between triangulated (or derived) categories and their dg enhancements. We explain when some interesting triangulated categories arising in algebraic geometry have a unique dg enhancement. This is the case, for example, for the unbounded derived category of quasi-coherent sheaves on an algebraic stack or for its full triangulated subcategory of perfect complexes. Moreover we give an account of the recent results about the possibility to lift exact functors between the bounded derived categories of coherent sheaves on smooth schemes to dg (quasi-)functors.

Numerical Schemes for the Hamilton-Jacobi and Level Set Equations on Triangulated Domains

NASA Technical Reports Server (NTRS)

Barth, Timothy J.; Sethian, James A.

2006-01-01

Borrowing from techniques developed for conservation law equations, we have developed both monotone and higher order accurate numerical schemes which discretize the Hamilton-Jacobi and level set equations on triangulated domains. The use of unstructured meshes containing triangles (2D) and tetrahedra (3D) easily accommodates mesh adaptation to resolve disparate level set feature scales with a minimal number of solution unknowns. The minisymposium talk will discuss these algorithmic developments and present sample calculations using our adaptive triangulation algorithm applied to various moving interface problems such as etching, deposition, and curvature flow.

Literacy Agents Online: E-Discussion Forums for Advancing Adults' Literacy Practices

ERIC Educational Resources Information Center

Guzzetti, Barbara J.; Foley, Leslie M.

2014-01-01

This study explored how adults used a self-selected online forum to advance their own and others' literacy practices. The study was a discourse-centered online ethnography using triangulated methods, including analysis of list archives, semi-structured and informal interviews, and document collection. These data were analyzed by discourse…

Monitoring and Stimulating Development of Integrated Professional Skills in University Study Programmes

ERIC Educational Resources Information Center

Wahlgren, Marie; Ahlberg, Anders

2013-01-01

In Swedish higher education, quality assurance mainly focuses on course module outcomes. With this in mind we developed a qualitative method to monitor and stimulate progression of learning in two modularized engineering study programmes. A set of core professional values and skills were triangulated through interviews with students, teachers,…

The Influence of Institutional Culture on Presidential Selection. ASHE 1987 Annual Meeting Paper.

ERIC Educational Resources Information Center

Kolman, Eileen M.; And Others

The influence of institutional culture on the selection of college presidents was investigated at three Catholic colleges sponsored by women's religious communities. The concepts of institutional saga and culture were used to describe the dynamics at work in presidential selection. The constant comparative method and triangulation (i.e., using…

Transformational Teaching Experience of a Novice Teacher: A Narrative of an Award-Winning Teacher

ERIC Educational Resources Information Center

Kumi-Yeboah, Alex; James, Waynne

2012-01-01

This research investigates the transformational teaching experiences of a novice award-winning teacher. Data collection consisted primarily of interviews and observations. To support these methods, we utilized field notes and reflection journals to triangulate the data. To become a successful teacher, "the teacher" passed through transformational…

Mixing Methods in Randomized Controlled Trials (RCTs): Validation, Contextualization, Triangulation, and Control

ERIC Educational Resources Information Center

Spillane, James P.; Pareja, Amber Stitziel; Dorner, Lisa; Barnes, Carol; May, Henry; Huff, Jason; Camburn, Eric

2010-01-01

In this paper we described how we mixed research approaches in a Randomized Control Trial (RCT) of a school principal professional development program. Using examples from our study we illustrate how combining qualitative and quantitative data can address some key challenges from validating instruments and measures of mediator variables to…

How Do Cognitive Function and Knowledge Affect Heart Failure Self-Care?

ERIC Educational Resources Information Center

Dickson, Victoria Vaughan; Lee, Christopher S.; Riegel, Barbara

2011-01-01

Despite extensive patient education, few heart failure (HF) patients master self-care. Impaired cognitive function may explain why patient education is ineffective. A concurrent triangulation mixed methods design was used to explore how knowledge and cognitive function influence HF self-care. A total of 41 adults with HF participated in interviews…

Strategies in an Arts Program for Adults with Atypical Communication

ERIC Educational Resources Information Center

Lukac, Christina

2017-01-01

The purpose of this study was to observe and implement strategies and adaptations in an arts program for adults with atypical communication due to developmental and intellectual disabilities. This study was conducted in the field using an action research approach with triangulated methods of data collection including semi-structured interviews,…

Held Back: The Impact of Curricular and Pedagogical Factors on Tested Achievement in High School Mathematics

ERIC Educational Resources Information Center

Agvanian, Zara

2013-01-01

This study examined the impact of curricular factors and teaching practices on students' tested achievement in mathematics, explored the best predictors of the tested achievement, and examined differences in the tested achievement among student subgroups. The study utilized qualitative and quantitative methods and triangulated findings from…

Wavelet-based hierarchical surface approximation from height fields

Treesearch

Sang-Mook Lee; A. Lynn Abbott; Daniel L. Schmoldt

2004-01-01

This paper presents a novel hierarchical approach to triangular mesh generation from height fields. A wavelet-based multiresolution analysis technique is used to estimate local shape information at different levels of resolution. Using predefined templates at the coarsest level, the method constructs an initial triangulation in which underlying object shapes are well...

Student and Teacher Perspectives of Technology Usage

ERIC Educational Resources Information Center

Elliott, Lori L.

2010-01-01

This study examined the use of technology by eighth grade students and teachers and perceptions of students and teachers toward technology use in the classroom and home. A mixed design method was selected to collect and analyze the data. Face-to-face interviews, field notes, and national survey results were used to triangulate the data. Three…

Adaptive Methods for Compressible Flow

DTIC Science & Technology

1994-03-01

labor -intensive task of purpose of this work is to demonstrate the generating acceptable surface triangulations, advantages of integrating the CAD/CAM...sintilar results). L 1 (’-1)(2sn~p) boundary error (MUSCL) The flow variables wre then given by .04 .78% M=asOIne/i .02 AM% v= acosO /sintt .01 .0 p

Impact of a Place-Based Education Curriculum on Indigenous Teacher and Students

ERIC Educational Resources Information Center

Sianturi, Murni; Chiang, Chia-Ling; Au Hurit, Andreas

2018-01-01

This study aimed to investigate the impact of a place-based education curriculum (PBE) on the indigenous teacher empowerment and improvement of indigenous students' learning achievement. This study applied mixed method research particularly concurrent triangulation design. The study took place in a remote indigenous elementary school in Papua,…

Authentic Reading, Writing, and Discussion: An Exploratory Study of a Pen Pal Project

ERIC Educational Resources Information Center

Gambrell, Linda B.; Hughes, Elizabeth M.; Calvert, Leah; Malloy, Jacquelynn A.; Igo, Brent

2011-01-01

In this exploratory study, reading, writing, and discussion were examined within the context of a pen pal intervention focusing on authentic literacy tasks. The study employed a mixed-method design with a triangulation-convergence model to explore the relationship between authentic literacy tasks and the literacy motivation of elementary students…

Educating Preservice School Librarians to Lead: A Study of Self-Perceived Transformational Leadership Behaviors

ERIC Educational Resources Information Center

Smith, Daniella

2011-01-01

The purpose of this study was to determine the factors that impacted the level of self-perceived transformational leadership potential in preservice school librarians who participated in a master's degree program in library and information studies focusing on leadership development. A mixed-method concurrent triangulation research design was…

Efficient low-bit-rate adaptive mesh-based motion compensation technique

NASA Astrophysics Data System (ADS)

Mahmoud, Hanan A.; Bayoumi, Magdy A.

2001-08-01

This paper proposes a two-stage global motion estimation method using a novel quadtree block-based motion estimation technique and an active mesh model. In the first stage, motion parameters are estimated by fitting block-based motion vectors computed using a new efficient quadtree technique, that divides a frame into equilateral triangle blocks using the quad-tree structure. Arbitrary partition shapes are achieved by allowing 4-to-1, 3-to-1 and 2-1 merge/combine of sibling blocks having the same motion vector . In the second stage, the mesh is constructed using an adaptive triangulation procedure that places more triangles over areas with high motion content, these areas are estimated during the first stage. finally the motion compensation is achieved by using a novel algorithm that is carried by both the encoder and the decoder to determine the optimal triangulation of the resultant partitions followed by affine mapping at the encoder. Computer simulation results show that the proposed method gives better performance that the conventional ones in terms of the peak signal-to-noise ration (PSNR) and the compression ratio (CR).

Global health policies that support the use of banked donor human milk: a human rights issue

PubMed Central

Arnold, Lois DW

2006-01-01

This review examines the role of donor human milk banking in international human rights documents and global health policies. For countries looking to improve child health, promotion, protection and support of donor human milk banks has an important role to play for the most vulnerable of infants and children. This review is based on qualitative triangulation research conducted for a doctoral dissertation. The three methods used in triangulation were 1) writing as a method of inquiry, 2) an integrative research review, and 3) personal experience and knowledge of the topic. Discussion of the international human rights documents and global health policies shows that there is a wealth of documentation to support promotion, protection and support of donor milk banking as an integral part of child health and survival. By utilizing these policy documents, health ministries, professional associations, and donor milk banking associations can find rationales for establishing, increasing or continuing to provide milk banking services in any country, and thereby improve the health of children and future generations of adults. PMID:17164001

Innovative Applications of Laser Scanning and Rapid Prototype Printing to Rock Breakdown Experiments

NASA Technical Reports Server (NTRS)

Bourke, Mary; Viles, Heather; Nicoll, Joe; Lyew-Ayee, Parris; Ghent, Rebecca; Holmlund, James

2008-01-01

We present the novel application of two technologies for use in rock breakdown experiments, i.e. close-range, ground-based 3D triangulation scanning and rapid prototype printing. These techniques aid analyses of form-process interactions across the range of scales relevant to breakdown (micron-m). This is achieved through (a) the creation of DEMs (which permit quantitative description and analysis of rock surface morphology and morphological change) and (b) the production of more realistically-shaped experimental blocks. We illustrate the use of these techniques, alongside appropriate data analysis routines, in experiments designed to investigate the persistence of fluvially-derived features in the face of subsequent wind abrasion and weathering. These techniques have a range of potential applications in experimental field and lab-based geomorphic studies beyond those specifically outlined here.

Cultural and social change of foreign students in Indonesia: The influence of Javanese Culture in Teaching Indonesian to Speakers of Other Languages (TISOL)

NASA Astrophysics Data System (ADS)

Saddhono, Kundharu

2018-03-01

Teaching Indonesian to Speakers of Other Languages (TISOL) program is increasingly in demand by people in various parts of the world. Foreign students learn a lot of Indonesian language in major cities in Indonesia. The purpose of this study is to explain the cultural and social changes of foreign students in Indonesia, especially in Java, which is following TISOL program. This study focused on the influence of Javanese culture on foreign students studying Indonesian in Java. Research method used is descriptive qualitative with ethnography approach. This research was conducted in TISOL program organized by in Central Java, East Java, and Yogyakarta. Sources of data used are documents and informants. The sampling technique used is purposive sampling. Purposive sampling is considered more capable to obtain complete data in the face of various realities. Data collection techniques are done by reviewing documents or records using content analysis techniques. Other techniques used are interview techniques with some students and lecturers to get data about the factors that affect the cultural and social changes of foreign students in Indonesia. Also, interviews were also conducted with teachers to request a different process in TISOL. The most common way used to improve validity in qualitative research is the triangulation technique. In this study used triangulation theory, triangulation method, and review of informants. The results show that using Javanese culture is very influential in the cultural and social changes of foreign students in Indonesia. Students become more enthusiastic and active in responding to learning in TISOL that is influenced by Javanese culture. The change comes from internal and external students. This change helps foreign students to understand Indonesian language and culture more comprehensively.

Geometry of the 1954 Fairview Peak-Dixie Valley earthquake sequence from a joint inversion of leveling and triangulation data

USGS Publications Warehouse

Hodgkinson, K.M.; Stein, R.S.; Marshall, G.

1996-01-01

In 1954, four earthquakes greater than Ms=6.0 occurred within a 30-km radius and in a period of 6 months. Elevation and angle changes calculated from repeated leveling and triangulation surveys which span the coseismic period provide constraints on the fault geometries and coseismic slip of the faults which were activated. The quality of the coseismic geodetic data is assessed. Corrections are applied to the leveling data for subsidence due to groundwater withdrawal in the Fallon area, and a rod miscalibration error of 150??30 ppm is isolated in leveling surveys made in 1967. The leveling and triangulation observations are then simultaneously inverted using the single value decomposition (SVD) inversion method to determine fault geometries and coseismic slip. Using SVD, it is possible to determine on which faults slip is resolvable given the data distribution. The faults are found to dip between 50?? and 80?? and extend to depths of 5 to 14 km. The geodetically derived slip values are generally equal to, or greater than, the maximum observed displacement along the surface scarps. Where slip is resolvable the geodetic data indicates the 1954 sequence contained a significant component of right-lateral slip. This is consistent with the N15??W trending shear zone which geodetic surveys have detected in western Nevada. Copyright 1996 by the American Geophysical Union.

Correlation and 3D-tracking of objects by pointing sensors

DOEpatents

Griesmeyer, J. Michael

2017-04-04

A method and system for tracking at least one object using a plurality of pointing sensors and a tracking system are disclosed herein. In a general embodiment, the tracking system is configured to receive a series of observation data relative to the at least one object over a time base for each of the plurality of pointing sensors. The observation data may include sensor position data, pointing vector data and observation error data. The tracking system may further determine a triangulation point using a magnitude of a shortest line connecting a line of sight value from each of the series of observation data from each of the plurality of sensors to the at least one object, and perform correlation processing on the observation data and triangulation point to determine if at least two of the plurality of sensors are tracking the same object. Observation data may also be branched, associated and pruned using new incoming observation data.

Coseismic slip distribution of the 1923 Kanto earthquake, Japan

USGS Publications Warehouse

Pollitz, F.F.; Nyst, M.; Nishimura, T.; Thatcher, W.

2005-01-01

The slip distribution associated with the 1923 M = 7.9 Kanto, Japan, earthquake is reexamined in light of new data and modeling. We utilize a combination of first-order triangulation, second-order triangulation, and leveling data in order to constrain the coseismic deformation. The second-order triangulation data, which have not been utilized in previous studies of 1923 coseismic deformation, are associated with only slightly smaller errors than the first-order triangulation data and expand the available triangulation data set by about a factor of 10. Interpretation of these data in terms of uniform-slip models in a companion study by Nyst et al. shows that a model involving uniform coseismic slip on two distinct rupture planes explains the data very well and matches or exceeds the fit obtained by previous studies, even one which involved distributed slip. Using the geometry of the Nyst et al. two-plane slip model, we perform inversions of the same geodetic data set for distributed slip. Our preferred model of distributed slip on the Philippine Sea plate interface has a moment magnitude of 7.86. We find slip maxima of ???8-9 m beneath Odawara and ???7-8 m beneath the Miura peninsula, with a roughly 2:1 ratio of strike-slip to dip-slip motion, in agreement with a previous study. However, the Miura slip maximum is imaged as a more broadly extended feature in our study, with the high-slip region continuing from the Miura peninsula to the southern Boso peninsula region. The second-order triangulation data provide good evidence for ???3 m right-lateral strike slip on a 35-km-long splay structure occupying the volume between the upper surface of the descending Philippine Sea plate and the southern Boso peninsula. Copyright 2005 by the American Geophysical Union.

Sines and Cosines. Part 2 of 3

NASA Technical Reports Server (NTRS)

Apostol, Tom M. (Editor)

1993-01-01

The Law of Sines and the Law of Cosines are introduced and demonstrated in this 'Project Mathematics' series video using both film footage and computer animation. This video deals primarily with the mathematical field of Trigonometry and explains how these laws were developed and their applications. One significant use is geographical and geological surveying. This includes both the triangulation method and the spirit leveling method. With these methods, it is shown how the height of the tallest mountain in the world, Mt. Everest, was determined.

Resolving the Quantitative-Qualitative Dilemma: A Critical Realist Approach

ERIC Educational Resources Information Center

Scott, David

2007-01-01

The philosophical issues underpinning the quantitative-qualitative divide in educational research are examined. Three types of argument which support a resolution are considered: pragmatism, false duality and warranty through triangulation. In addition a number of proposed strategies--alignment, sequencing, translation and triangulation--are…

Determining Position Inside Non-industrial Buildings Using Ultrasound Transducers

PubMed Central

Escudero, Francesc; Margalef, Jordi; Luengo, Sonia; Alsina, Maria; Ribes, Josep M.; Pérez, Juan

2007-01-01

The position determination inside a building where no GPS signal is being received can be ascertained using laser transmitters in industrial situations where there are no people or using triangulation of the signal strength, normally electro-magnetic signals, if the required accuracy is more than a metre. Our solution is aimed at situations where people are present and where the required accuracy is less than 30 cm, such as in shopping precincts or supermarkets. To achieve this, a network of ultrasonic transmitters is fitted into the ceiling which receives a synchronised time signal. Each transmitter has a unique identifier code and emits its code with a delay with respect to the common time signal which is proportional to its code number with an ASK modulation over the ultrasonic band centred on 40 KHz. The receivers circulating beneath the transmitters receive the codes of those within their detection range, translate the time delays into distances and then obtain their position by triangulation since the receivers know the position of every transmitter. Since the receivers are not synchronised with the common time signal or the actual speed of the sound, whose value varies appreciably with temperature, relative humidity and atmospheric pressure, a consecutive approximation algorithm has been introduced. This is based on the fact that the Z coordinator of the receiver is known and constant and thus it is possible, with only three different identifiers received, to deduce the phase of the common time signal and estimate the speed of the sound with a fourth identifier. PMID:28903247

Spreading of non-planar non-axisymmetric gravity and turbidity currents

NASA Astrophysics Data System (ADS)

Zgheib, Nadim; Bonometti, Thomas; Balachandar, S.

2014-11-01

The dynamics of non-axisymmetric turbidity currents is considered here. The study comprises a series of experiments for which a finite volume of particle-laden solution is released into fresh water. A mixture of water and polystyrene particles of diameter 280

Non-destructive 3D shape measurement of transparent and black objects with thermal fringes

NASA Astrophysics Data System (ADS)

Brahm, Anika; Rößler, Conrad; Dietrich, Patrick; Heist, Stefan; Kühmstedt, Peter; Notni, Gunther

2016-05-01

Fringe projection is a well-established optical method for the non-destructive contactless three-dimensional (3D) measurement of object surfaces. Typically, fringe sequences in the visible wavelength range (VIS) are projected onto the surfaces of objects to be measured and are observed by two cameras in a stereo vision setup. The reconstruction is done by finding corresponding pixels in both cameras followed by triangulation. Problems can occur if the properties of some materials disturb the measurements. If the objects are transparent, translucent, reflective, or strongly absorbing in the VIS range, the projected patterns cannot be recorded properly. To overcome these challenges, we present a new alternative approach in the infrared (IR) region of the electromagnetic spectrum. For this purpose, two long-wavelength infrared (LWIR) cameras (7.5 - 13 μm) are used to detect the emitted heat radiation from surfaces which is induced by a pattern projection unit driven by a CO2 laser (10.6 μm). Thus, materials like glass or black objects, e.g. carbon fiber materials, can be measured non-destructively without the need of any additional paintings. We will demonstrate the basic principles of this heat pattern approach and show two types of 3D systems based on a freeform mirror and a GOBO wheel (GOes Before Optics) projector unit.

The 3-D unstructured mesh generation using local transformations

NASA Technical Reports Server (NTRS)

Barth, Timothy J.

1993-01-01

The topics are presented in viewgraph form and include the following: 3D combinatorial edge swapping; 3D incremental triangulation via local transformations; a new approach to multigrid for unstructured meshes; surface mesh generation using local transforms; volume triangulations; viscous mesh generation; and future directions.

Triangulation in aetiological epidemiology

PubMed Central

Lawlor, Debbie A; Tilling, Kate; Davey Smith, George

2016-01-01

Abstract Triangulation is the practice of obtaining more reliable answers to research questions through integrating results from several different approaches, where each approach has different key sources of potential bias that are unrelated to each other. With respect to causal questions in aetiological epidemiology, if the results of different approaches all point to the same conclusion, this strengthens confidence in the finding. This is particularly the case when the key sources of bias of some of the approaches would predict that findings would point in opposite directions if they were due to such biases. Where there are inconsistencies, understanding the key sources of bias of each approach can help to identify what further research is required to address the causal question. The aim of this paper is to illustrate how triangulation might be used to improve causal inference in aetiological epidemiology. We propose a minimum set of criteria for use in triangulation in aetiological epidemiology, summarize the key sources of bias of several approaches and describe how these might be integrated within a triangulation framework. We emphasize the importance of being explicit about the expected direction of bias within each approach, whenever this is possible, and seeking to identify approaches that would be expected to bias the true causal effect in different directions. We also note the importance, when comparing results, of taking account of differences in the duration and timing of exposures. We provide three examples to illustrate these points. PMID:28108528

Bridging the Implementation Gap: An Ethnographic Study of English Teachers' Implementation of the Curriculum Reform in China

ERIC Educational Resources Information Center

Yan, Chunmei; He, Chuanjun

2012-01-01

This article reports on a study of secondary English teachers' perceptions of and implementation of the New English Curriculum Reform in China initiated in 2009. Ethnography and triangulated data collection methods were employed to gather information about three senior secondary English teachers' interpretations of the New Curriculum and their…

How Do We Know What Is Happening Online?: A Triangulated Approach to Data Analysis

ERIC Educational Resources Information Center

Charalampidi, Marina; Hammond, Michael

2016-01-01

This paper discusses the process of analysing online discussion and argues for the merits of mixed methods. Much research of online participation and e-learning has been either message focused or person focused analysis. The former covers methodologies such as content and discourse analysis, the latter interviewing and surveys. The paper discusses…

Self-Awareness and Leadership Skills of Female Students in Outdoor Camp

ERIC Educational Resources Information Center

Esentas, Melike; Özbey, Selhan; Güzel, Pinar

2017-01-01

This study aims to determine the role of youth camp practices, organised by the Ministry of Youth and Sports, in the development of self-awareness and leadership skills of female students participating in youth camps. As a result of analysis of the data collected with triangulation method--observation, focus group discussions and document…

In the Eye of the Beholder: Mothers' Perceptions of Poor Neighborhoods as Places to Raise Children

ERIC Educational Resources Information Center

Dahl, Trayci; Ceballo, Rosario; Huerta, Marisela

2010-01-01

This study explores how mothers facing similar neighborhood conditions evaluate their neighborhoods as places to raise children. The authors relied upon a triangulation of methods, using both quantitative and qualitative methodologies, with a sample of 91 low-income mothers. Content analysis of qualitative interviews revealed that mothers often…

Novel Methods for Electromagnetic Simulation and Design

DTIC Science & Technology

2016-08-03

The resulting discretized integral equations are compatible with fast multipoleaccelerated solvers and will form the basis for high fidelity...expansion”) which are high-order, efficient and easy to use on arbitrarily triangulated surfaces. The resulting discretized integral equations are...created a user interface compatible with both low and high order discretizations , and implemented the generalized Debye approach of [4]. The

An Evaluation of a Service-Learning Model for Criminal Justice Undergraduate Students

ERIC Educational Resources Information Center

Hirschinger-Blank, Nancy Beth; Simons, Lori; Kenyon, Alexandra

2009-01-01

A triangulation mixed-methods design was used to measure differences in service-learning outcomes for 32 students enrolled in criminal justice courses during the academic years 2003 (n = 16) and 2005 (n = 16). Results show that service-learners increase their political awareness and course value but experience a decrease in problem-solving skills…

LETs and NETs: Exploring How Teachers from Diverse Cultural Backgrounds Impact Student Motivation and Preferences

ERIC Educational Resources Information Center

Wong, Ruth

2014-01-01

This paper, an exploratory case study, examines how students' preferences and motivation to learn English are influenced by their perceptions of teaching practices--both of native English teachers and local English teachers. To better understand the context of this research question, this study adopts a method of triangulation in collecting data:…

A Qualitatively Different Experience: Mainstreaming Pupils with a Visual Impairment in Northern Ireland

ERIC Educational Resources Information Center

Gray, Colette

2009-01-01

This paper reports the experiences of special education needs co-ordinators (SENCOs) on the inclusion of pupils with a visual impairment (VI) in mainstream schools in Northern Ireland. A mixed method approach (postal questionnaire survey (n=113) and interviews (n=6)) was utilised to triangulate the findings. The results indicate an inverse…

"We Can't Change Much Unless the Exams Change": Teachers' Dilemmas in the Curriculum Reform in China

ERIC Educational Resources Information Center

Yan, Chunmei

2015-01-01

This article reports on a study of English secondary teachers' perceptions of and implementation of the New English Curriculum Reform in China. Triangulated data collection methods were employed to gather information about teachers' perceptions of the New Curriculum and their teaching behaviours in Central China. An implementation gap emerged…

Internet Access, Use and Sharing Levels among Students during the Teaching-Learning Process

ERIC Educational Resources Information Center

Tutkun, Omer F.

2011-01-01

The purpose of this study was to determine the awareness among students and levels regarding student access, use, and knowledge sharing during the teaching-learning process. The triangulation method was utilized in this study. The population of the research universe was 21,747. The student sample population was 1,292. Two different data collection…

A Triangulation Method to Dismantling a Disciplinary "Big Deal"

ERIC Educational Resources Information Center

Dawson, Diane

2015-01-01

In late 2012, it appeared that the University Library, University of Saskatchewan would likely no longer be able to afford to subscribe to the entire American Chemical Society "Big Deal" of 36 journals. Difficult choices would need to be made regarding which titles to retain as individual subscriptions. In an effort to arrive at the most…

Photogrammetric Point Clouds Generation in Urban Areas from Integrated Image Matching and Segmentation

NASA Astrophysics Data System (ADS)

Ye, L.; Wu, B.

2017-09-01

High-resolution imagery is an attractive option for surveying and mapping applications due to the advantages of high quality imaging, short revisit time, and lower cost. Automated reliable and dense image matching is essential for photogrammetric 3D data derivation. Such matching, in urban areas, however, is extremely difficult, owing to the complexity of urban textures and severe occlusion problems on the images caused by tall buildings. Aimed at exploiting high-resolution imagery for 3D urban modelling applications, this paper presents an integrated image matching and segmentation approach for reliable dense matching of high-resolution imagery in urban areas. The approach is based on the framework of our existing self-adaptive triangulation constrained image matching (SATM), but incorporates three novel aspects to tackle the image matching difficulties in urban areas: 1) occlusion filtering based on image segmentation, 2) segment-adaptive similarity correlation to reduce the similarity ambiguity, 3) improved dense matching propagation to provide more reliable matches in urban areas. Experimental analyses were conducted using aerial images of Vaihingen, Germany and high-resolution satellite images in Hong Kong. The photogrammetric point clouds were generated, from which digital surface models (DSMs) were derived. They were compared with the corresponding airborne laser scanning data and the DSMs generated from the Semi-Global matching (SGM) method. The experimental results show that the proposed approach is able to produce dense and reliable matches comparable to SGM in flat areas, while for densely built-up areas, the proposed method performs better than SGM. The proposed method offers an alternative solution for 3D surface reconstruction in urban areas.

Communication Intervention in an Organization: Measuring the Results through a Triangulation Approach.

ERIC Educational Resources Information Center

Zamanou, Sonia; Glaser, Susan R.

A study examined organizational culture change to determine the effectiveness of a communication based intervention program to increase productivity and motivation. The cultural change was measured through a triangulation approach combining questionnaires, interview data and direct observation. Pre- and post-intervention data were obtained in the…

The Movement of Conflict in Organizations: The Joint Dynamics of Splitting and Triangulation.

ERIC Educational Resources Information Center

Smith, Kenwyn K.

1989-01-01

Based on a long-term public school system study, the paper examines the sociopsychological process through which conflicts move around in organizations and are transported from one place to another. The conceptualization draws on "triangulation" from social psychology and family therapy and "splitting," developed in…

The evaluation of student-centredness of teaching and learning: a new mixed-methods approach

PubMed Central

Lemos, Ana R.; Sandars, John E.; Alves, Palmira

2014-01-01

Objectives The aim of the study was to develop and consider the usefulness of a new mixed-methods approach to evaluate the student-centredness of teaching and learning on undergraduate medical courses. An essential paradigm for the evaluation was the coherence between how teachers conceptualise their practice (espoused theories) and their actual practice (theories-in-use). Methods The context was a module within an integrated basic sciences course in an undergraduate medical degree programme. The programme had an explicit intention of providing a student-centred curriculum. A content analysis framework based on Weimer’s dimensions of student-centred teaching was used to analyze data collected from individual interviews with seven teachers to identify espoused theories and 34h of classroom observations and one student focus group to identify theories-in-use. The interviewees were identified by purposeful sampling. The findings from the three methods were triangulated to evaluate the student-centredness of teaching and learning on the course. Results Different, but complementary, perspectives of the student-centredness of teaching and learning were identified by each method. The triangulation of the findings revealed coherence between the teachers’ espoused theories and theories-in-use. Conclusions A mixed-methods approach that combined classroom observations with interviews from a purposeful sample of teachers and students offered a useful evaluation of the extent of student-centredness of teaching and learning of this basic science course. Our case study suggests that this new approach is applicable to other courses in medical education. PMID:25341225

A new approach for categorizing pig lying behaviour based on a Delaunay triangulation method.

PubMed

Nasirahmadi, A; Hensel, O; Edwards, S A; Sturm, B

2017-01-01

Machine vision-based monitoring of pig lying behaviour is a fast and non-intrusive approach that could be used to improve animal health and welfare. Four pens with 22 pigs in each were selected at a commercial pig farm and monitored for 15 days using top view cameras. Three thermal categories were selected relative to room setpoint temperature. An image processing technique based on Delaunay triangulation (DT) was utilized. Different lying patterns (close, normal and far) were defined regarding the perimeter of each DT triangle and the percentages of each lying pattern were obtained in each thermal category. A method using a multilayer perceptron (MLP) neural network, to automatically classify group lying behaviour of pigs into three thermal categories, was developed and tested for its feasibility. The DT features (mean value of perimeters, maximum and minimum length of sides of triangles) were calculated as inputs for the MLP classifier. The network was trained, validated and tested and the results revealed that MLP could classify lying features into the three thermal categories with high overall accuracy (95.6%). The technique indicates that a combination of image processing, MLP classification and mathematical modelling can be used as a precise method for quantifying pig lying behaviour in welfare investigations.

Automated detection of coronal mass ejections in three-dimensions using multi-viewpoint observations

NASA Astrophysics Data System (ADS)

Hutton, J.; Morgan, H.

2017-03-01

A new, automated method of detecting coronal mass ejections (CMEs) in three dimensions for the LASCO C2 and STEREO COR2 coronagraphs is presented. By triangulating isolated CME signal from the three coronagraphs over a sliding window of five hours, the most likely region through which CMEs pass at 5 R⊙ is identified. The centre and size of the region gives the most likely direction of propagation and approximate angular extent. The Automated CME Triangulation (ACT) method is tested extensively using a series of synthetic CME images created using a wireframe flux rope density model, and on a sample of real coronagraph data; including halo CMEs. The accuracy of the angular difference (σ) between the detection and true input of the synthetic CMEs is σ = 7.14°, and remains acceptable for a broad range of CME positions relative to the observer, the relative separation of the three observers and even through the loss of one coronagraph. For real data, the method gives results that compare well with the distribution of low coronal sources and results from another instrument and technique made further from the Sun. The true three dimension (3D)-corrected kinematics and mass/density are discussed. The results of the new method will be incorporated into the CORIMP database in the near future, enabling improved space weather diagnostics and forecasting.

Automatic 3D reconstruction of electrophysiology catheters from two-view monoplane C-arm image sequences.

PubMed

Baur, Christoph; Milletari, Fausto; Belagiannis, Vasileios; Navab, Nassir; Fallavollita, Pascal

2016-07-01

Catheter guidance is a vital task for the success of electrophysiology interventions. It is usually provided through fluoroscopic images that are taken intra-operatively. The cardiologists, who are typically equipped with C-arm systems, scan the patient from multiple views rotating the fluoroscope around one of its axes. The resulting sequences allow the cardiologists to build a mental model of the 3D position of the catheters and interest points from the multiple views. We describe and compare different 3D catheter reconstruction strategies and ultimately propose a novel and robust method for the automatic reconstruction of 3D catheters in non-synchronized fluoroscopic sequences. This approach does not purely rely on triangulation but incorporates prior knowledge about the catheters. In conjunction with an automatic detection method, we demonstrate the performance of our method compared to ground truth annotations. In our experiments that include 20 biplane datasets, we achieve an average reprojection error of 0.43 mm and an average reconstruction error of 0.67 mm compared to gold standard annotation. In clinical practice, catheters suffer from complex motion due to the combined effect of heartbeat and respiratory motion. As a result, any 3D reconstruction algorithm via triangulation is imprecise. We have proposed a new method that is fully automatic and highly accurate to reconstruct catheters in three dimensions.

An advanced analysis method of initial orbit determination with too short arc data

NASA Astrophysics Data System (ADS)

Li, Binzhe; Fang, Li

2018-02-01

This paper studies the initial orbit determination (IOD) based on space-based angle measurement. Commonly, these space-based observations have short durations. As a result, classical initial orbit determination algorithms give poor results, such as Laplace methods and Gauss methods. In this paper, an advanced analysis method of initial orbit determination is developed for space-based observations. The admissible region and triangulation are introduced in the method. Genetic algorithm is also used for adding some constraints of parameters. Simulation results show that the algorithm can successfully complete the initial orbit determination.

Tactile Robotic Topographical Mapping Without Force or Contact Sensors

NASA Technical Reports Server (NTRS)

Burke, Kevin; Melko, Joseph; Krajewski, Joel; Cady, Ian

2008-01-01

A method of topographical mapping of a local solid surface within the range of motion of a robot arm is based on detection of contact between the surface and the end effector (the fixture or tool at the tip of the robot arm). The method was conceived to enable mapping of local terrain by an exploratory robot on a remote planet, without need to incorporate delicate contact switches, force sensors, a vision system, or other additional, costly hardware. The method could also be used on Earth for determining the size and shape of an unknown surface in the vicinity of a robot, perhaps in an unanticipated situation in which other means of mapping (e.g., stereoscopic imaging or laser scanning with triangulation) are not available. The method uses control software modified to utilize the inherent capability of the robotic control system to measure the joint positions, the rates of change of the joint positions, and the electrical current demanded by the robotic arm joint actuators. The system utilizes these coordinate data and the known robot-arm kinematics to compute the position and velocity of the end effector, move the end effector along a specified trajectory, place the end effector at a specified location, and measure the electrical currents in the joint actuators. Since the joint actuator current is approximately proportional to the actuator forces and torques, a sudden rise in joint current, combined with a slowing of the joint, is a possible indication of actuator stall and surface contact. Hence, even though the robotic arm is not equipped with contact sensors, it is possible to sense contact (albeit with reduced sensitivity) as the end effector becomes stalled against a surface that one seeks to measure.

Thickness ratio effects on quasistatic actuation and sensing behavior of laminate magnetoelectric cantilevers

NASA Astrophysics Data System (ADS)

Wang, Yezuo; Atulasimha, Jayasimha; Clarke, Joshua; Sundaresan, Vishnu B.

2010-04-01

In this work, the magnetoelectric cantilever composed of a layer of Galfenol and a layer of PZT-5H is studied for novel applications such as surgical ablation tools and cutting tools for machining applications. For developing a suitable model for the magnetoelectric cantilever, an energy based approach for the non-linear constitutive behavior of the magnetostrictive material and linear piezoelectric constitutive equations will be coupled with Euler Bernoulli model for composite beams. The cantilever is held in a uniform magnetic field and the magnetic field is measured by a Gaussmeter. The tip-deflection of the cantilever is detected by a laser triangulation sensor. The piezoelectric response can be studied with low noise preamplifier. Four PZT-5H layers with different thickness are separately bonded on the top of the same Galfenol layer and characterized to study the thickness ratio effects on the quasistatic actuation and sensing behavior of the composite cantilever.

Bistatic LIDAR experiment proposed for the shuttle/tethered satellite system missions

NASA Technical Reports Server (NTRS)

Mccomas, D. J.; Spense, H. E.; Karl, R. R.; Horak, H. G.; Wilkerson, T. D.

1986-01-01

A new experiment concept has been proposed for the shuttle/tethered satellite system missions, which can provide high resolution, global density mappings of certain ionospheric species. The technique utilizes bistatic LIDAR to take advantage of the unique dual platform configuration offered by these missions. A tuned, shuttle-based laser is used to excite a column of the atmosphere adjacent to the tethered satellite, while triangulating photometic detectors on the satellite are employed to measure the fluorescence from sections of the column. The fluorescent intensity at the detectors is increased about six decades over both ground-based and monostatic shuttle-based LIDAR sounding of the same region. In addition, the orbital motion of the Shuttle provides for quasi-global mapping unattainable with ground-based observations. Since this technique provides such vastly improved resolution on a synoptic scale, many important middle atmospheric studies, heretofore untenable, may soon be addressed.

Evaluating Team Project-Work Using Triangulation: Lessons from Communities in Northern Ghana

ERIC Educational Resources Information Center

Clark, Gordon; Jasaw, Godfred Seidu

2014-01-01

This paper uses triangulation to assess key aspects of a team-based, participatory action research programme for undergraduates in rural communities across northern Ghana. The perceptions of the programme and its effects on the students, staff and host communities are compared, showing areas of agreement and disagreement. The successes of the…

The Triangulation Interview Form: A Possible Criterion for Field-Based Objectives.

ERIC Educational Resources Information Center

Licata, Joseph W.; Norman, Reuben L.

1979-01-01

To test the general reliability and validity of the Triangulation Interview Form (TIF), 52 observers viewed a videotape simulation of an interview situation. Agreement among observers for each of 16 TIF questions ranged from 85 to 98 percent. Observers significantly discriminated between eight behaviors judged complete and eight behaviors judged…

Triangulation in aetiological epidemiology.

PubMed

Lawlor, Debbie A; Tilling, Kate; Davey Smith, George

2016-12-01

Triangulation is the practice of obtaining more reliable answers to research questions through integrating results from several different approaches, where each approach has different key sources of potential bias that are unrelated to each other. With respect to causal questions in aetiological epidemiology, if the results of different approaches all point to the same conclusion, this strengthens confidence in the finding. This is particularly the case when the key sources of bias of some of the approaches would predict that findings would point in opposite directions if they were due to such biases. Where there are inconsistencies, understanding the key sources of bias of each approach can help to identify what further research is required to address the causal question. The aim of this paper is to illustrate how triangulation might be used to improve causal inference in aetiological epidemiology. We propose a minimum set of criteria for use in triangulation in aetiological epidemiology, summarize the key sources of bias of several approaches and describe how these might be integrated within a triangulation framework. We emphasize the importance of being explicit about the expected direction of bias within each approach, whenever this is possible, and seeking to identify approaches that would be expected to bias the true causal effect in different directions. We also note the importance, when comparing results, of taking account of differences in the duration and timing of exposures. We provide three examples to illustrate these points. © The Author 2017. Published by Oxford University Press on behalf of the International Epidemiological Association.

Chinese Teachers' Self-Reported Beliefs and Practices Related to Majority and Minority Students in Xinjiang Uygur Autonomous Region

ERIC Educational Resources Information Center

Newton, Hongyan Z.

2011-01-01

This study begins to address the questions of what beliefs Chinese teachers hold about teaching and learning, about different student groups, and how these beliefs and expectations mediate their daily instructional practices. A triangulated mixed methods design was used for this study. This is a type of design in which different but complementary…

Effectiveness of Teaching Approaches of In-Service Training Courses for EFL Teachers in Jordanian Schools

ERIC Educational Resources Information Center

Al-Wreikat, Yazan Abdel Aziz Semreen; Bin Abdullah, Muhamad Kamarul Kabilan

2011-01-01

This paper focuses on the impact of the organization of teaching approaches on the effectiveness of training for Jordanian EFL teachers. The sample for this study is drawn from all government schools in the Hashemite Kingdom of Jordan. The study uses a mixed-method approach whereby findings are triangulated throughout (in interviews, observations,…

a Variant of Lsd-Slam Capable of Processing High-Speed Low-Framerate Monocular Datasets

NASA Astrophysics Data System (ADS)

Schmid, S.; Fritsch, D.

2017-11-01

We develop a new variant of LSD-SLAM, called C-LSD-SLAM, which is capable of performing monocular tracking and mapping in high-speed low-framerate situations such as those of the KITTI datasets. The methods used here are robust against the influence of erronously triangulated points near the epipolar direction, which otherwise causes tracking divergence.

Examining a Massive Multiplayer Online Role-Playing Game as a Digital Game-Based Learning Platform

ERIC Educational Resources Information Center

Wu, Min Lun; Richards, Kari; Saw, Guan Kung

2014-01-01

A concurrent triangulation mixed-method research design was used to investigate 19 casual gamers' or non-gamers' use of a popular massive multiplayer online role-playing game (MMORPG), Everquest 2, as an alternative pedagogical tool to support communicative use of the English language. This study poses that MMORPGs could serve as a virtually rich…

Exploring Factors that Predict Preservice Teachers' Intentions to Use Web 2.0 Technologies Using Decomposed Theory of Planned Behavior

ERIC Educational Resources Information Center

Sadaf, Ayesha; Newby, Timothy J.; Ertmer, Peggy A.

2013-01-01

This study investigated factors that predict preservice teachers' intentions to use Web 2.0 technologies in their future classrooms. The researchers used a mixed-methods research design and collected qualitative interview data (n = 7) to triangulate quantitative survey data (n = 286). Results indicate that positive attitudes and perceptions of…

Evaluating Creative Thinking of Rn-Bsn Students in the Course of Clinical Case Study and Practicum

ERIC Educational Resources Information Center

Ku, Ya-Lie

2015-01-01

This case study evaluated creative thinking of RN-BSN students in the course of clinical case study and practicum. Study design used quantitative and qualitative evaluations of creative thinking of RN-BSN students by triangulation method in the course of clinical case study and practicum. Sixty RN-BSN students self-perceived the changing levels of…

Movement pattern recognition in basketball free-throw shooting.

PubMed

Schmidt, Andrea

2012-04-01

The purpose of the present study was to analyze the movement patterns of free-throw shooters in basketball at different skill levels. There were two points of interest. First, to explore what information can be drawn from the movement pattern and second, to examine the methodological possibilities of pattern analysis. To this end, several qualitative and quantitative methods were employed. The resulting data were converged in a triangulation. Using a special kind of ANN named Dynamically Controlled Networks (DyCoN), a 'complex feature' consisting of several isolated features (angle displacements and velocities of the articulations of the kinematic chain) was calculated. This 'complex feature' was displayed by a trajectory combining several neurons of the network, reflecting the devolution of the twelve angle measures over the time course of each shooting action. In further network analyses individual characteristics were detected, as well as movement phases. Throwing patterns were successfully classified and the stability and variability of the realized pattern were established. The movement patterns found were clearly individually shaped as well as formed by the skill level. The triangulation confirmed the individual movement organizations. Finally, a high stability of the network methods was documented. Copyright © 2012. Published by Elsevier B.V.

Method and apparatus for determining the coordinates of an object

DOEpatents

Pedersen, Paul S.

2002-01-01

A simplified method and related apparatus are described for determining the location of points on the surface of an object by varying, in accordance with a unique sequence, the intensity of each illuminated pixel directed to the object surface, and detecting at known detector pixel locations the intensity sequence of reflected illumination from the surface of the object whereby the identity and location of the originating illuminated pixel can be determined. The coordinates of points on the surface of the object are then determined by conventional triangulation methods.

The evaluation of student-centredness of teaching and learning: a new mixed-methods approach.

PubMed

Lemos, Ana R; Sandars, John E; Alves, Palmira; Costa, Manuel J

2014-08-14

The aim of the study was to develop and consider the usefulness of a new mixed-methods approach to evaluate the student-centredness of teaching and learning on undergraduate medical courses. An essential paradigm for the evaluation was the coherence between how teachers conceptualise their practice (espoused theories) and their actual practice (theories-in-use). The context was a module within an integrated basic sciences course in an undergraduate medical degree programme. The programme had an explicit intention of providing a student-centred curriculum. A content analysis framework based on Weimer's dimensions of student-centred teaching was used to analyze data collected from individual interviews with seven teachers to identify espoused theories and 34h of classroom observations and one student focus group to identify theories-in-use. The interviewees were identified by purposeful sampling. The findings from the three methods were triangulated to evaluate the student-centredness of teaching and learning on the course. Different, but complementary, perspectives of the student-centredness of teaching and learning were identified by each method. The triangulation of the findings revealed coherence between the teachers' espoused theories and theories-in-use. A mixed-methods approach that combined classroom observations with interviews from a purposeful sample of teachers and students offered a useful evaluation of the extent of student-centredness of teaching and learning of this basic science course. Our case study suggests that this new approach is applicable to other courses in medical education.

Multi-static networked 3D ladar for surveillance and access control

NASA Astrophysics Data System (ADS)

Wang, Y.; Ogirala, S. S. R.; Hu, B.; Le, Han Q.

2007-04-01

A theoretical design and simulation of a 3D ladar system concept for surveillance, intrusion detection, and access control is described. It is a non-conventional system architecture that consists of: i) multi-static configuration with an arbitrarily scalable number of transmitters (Tx's) and receivers (Rx's) that form an optical wireless code-division-multiple-access (CDMA) network, and ii) flexible system architecture with modular plug-and-play components that can be deployed for any facility with arbitrary topology. Affordability is a driving consideration; and a key feature for low cost is an asymmetric use of many inexpensive Rx's in conjunction with fewer Tx's, which are generally more expensive. The Rx's are spatially distributed close to the surveyed area for large coverage, and capable of receiving signals from multiple Tx's with moderate laser power. The system produces sensing information that scales as NxM, where N, M are the number of Tx's and Rx's, as opposed to linear scaling ~N in non-network system. Also, for target positioning, besides laser pointing direction and time-of-flight, the algorithm includes multiple point-of-view image fusion and triangulation for enhanced accuracy, which is not applicable to non-networked monostatic ladars. Simulation and scaled model experiments on some aspects of this concept are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

OWEN,STEVEN J.

A method for decomposing a volume with a prescribed quadrilateral surface mesh, into a hexahedral-dominated mesh is proposed. With this method, known as Hex-Morphing (H-Morph), an initial tetrahedral mesh is provided. Tetrahedral are transformed and combined starting from the boundary and working towards the interior of the volume. The quadrilateral faces of the hexahedra are treated as internal surfaces, which can be recovered using constrained triangulation techniques. Implementation details of the edge and face recovery process are included. Examples and performance of the H-Morph algorithm are also presented.

A new route for dental graduates.

PubMed

Pocock, Ian

2007-01-01

The two dental faculties believe that the new examination will provide a modern, fit-for-purpose, innovative assessment for today's young dentist. The introduction of a workplace-based portfolio removes the reliance on traditional tests of knowledge and, together with the OSCE elements, allows for triangulation of methods to test the areas set out in the GPT Curriculum. Furthermore, the faculties hope that the evaluation of workplace-based experience, and decreased reliance on traditional examination methods, will also have greater meaning for young dental graduates.

The Marginalized "Model" Minority: An Empirical Examination of the Racial Triangulation of Asian Americans

ERIC Educational Resources Information Center

Xu, Jun; Lee, Jennifer C.

2013-01-01

In this article, we propose a shift in race research from a one-dimensional hierarchical approach to a multidimensional system of racial stratification. Building upon Claire Kim's (1999) racial triangulation theory, we examine how the American public rates Asians relative to blacks and whites along two dimensions of racial stratification: racial…

Multi-Sensor Triangulation of Multi-Source Spatial Data

NASA Technical Reports Server (NTRS)

Habib, Ayman; Kim, Chang-Jae; Bang, Ki-In

2007-01-01

The introduced methodologies are successful in: a) Ising LIDAR features for photogrammetric geo-refererncing; b) Delivering a geo-referenced imagery of the same quality as point-based geo-referencing procedures; c) Taking advantage of the synergistic characteristics of spatial data acquisition systems. The triangulation output can be used for the generation of 3-D perspective views.

Making the Most of Obesity Research: Developing Research and Policy Objectives through Evidence Triangulation

ERIC Educational Resources Information Center

Oliver, Kathryn; Aicken, Catherine; Arai, Lisa

2013-01-01

Drawing lessons from research can help policy makers make better decisions. If a large and methodologically varied body of research exists, as with childhood obesity, this is challenging. We present new research and policy objectives for child obesity developed by triangulating user involvement data with a mapping study of interventions aimed at…

An Array of Qualitative Data Analysis Tools: A Call for Data Analysis Triangulation

ERIC Educational Resources Information Center

Leech, Nancy L.; Onwuegbuzie, Anthony J.

2007-01-01

One of the most important steps in the qualitative research process is analysis of data. The purpose of this article is to provide elements for understanding multiple types of qualitative data analysis techniques available and the importance of utilizing more than one type of analysis, thus utilizing data analysis triangulation, in order to…

Discovery and problem solving: Triangulation as a weak heuristic

NASA Technical Reports Server (NTRS)

Rochowiak, Daniel

1987-01-01

Recently the artificial intelligence community has turned its attention to the process of discovery and found that the history of science is a fertile source for what Darden has called compiled hindsight. Such hindsight generates weak heuristics for discovery that do not guarantee that discoveries will be made but do have proven worth in leading to discoveries. Triangulation is one such heuristic that is grounded in historical hindsight. This heuristic is explored within the general framework of the BACON, GLAUBER, STAHL, DALTON, and SUTTON programs. In triangulation different bases of information are compared in an effort to identify gaps between the bases. Thus, assuming that the bases of information are relevantly related, the gaps that are identified should be good locations for discovery and robust analysis.

Improved stereo matching applied to digitization of greenhouse plants

NASA Astrophysics Data System (ADS)

Zhang, Peng; Xu, Lihong; Li, Dawei; Gu, Xiaomeng

2015-03-01

The digitization of greenhouse plants is an important aspect of digital agriculture. Its ultimate aim is to reconstruct a visible and interoperable virtual plant model on the computer by using state-of-the-art image process and computer graphics technologies. The most prominent difficulties of the digitization of greenhouse plants include how to acquire the three-dimensional shape data of greenhouse plants and how to carry out its realistic stereo reconstruction. Concerning these issues an effective method for the digitization of greenhouse plants is proposed by using a binocular stereo vision system in this paper. Stereo vision is a technique aiming at inferring depth information from two or more cameras; it consists of four parts: calibration of the cameras, stereo rectification, search of stereo correspondence and triangulation. Through the final triangulation procedure, the 3D point cloud of the plant can be achieved. The proposed stereo vision system can facilitate further segmentation of plant organs such as stems and leaves; moreover, it can provide reliable digital samples for the visualization of greenhouse tomato plants.

Meshes optimized for discrete exterior calculus (DEC).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mousley, Sarah C.; Deakin, Michael; Knupp, Patrick

We study the optimization of an energy function used by the meshing community to measure and improve mesh quality. This energy is non-traditional because it is dependent on both the primal triangulation and its dual Voronoi (power) diagram. The energy is a measure of the mesh's quality for usage in Discrete Exterior Calculus (DEC), a method for numerically solving PDEs. In DEC, the PDE domain is triangulated and this mesh is used to obtain discrete approximations of the continuous operators in the PDE. The energy of a mesh gives an upper bound on the error of the discrete diagonal approximationmore » of the Hodge star operator. In practice, one begins with an initial mesh and then makes adjustments to produce a mesh of lower energy. However, we have discovered several shortcomings in directly optimizing this energy, e.g. its non-convexity, and we show that the search for an optimized mesh may lead to mesh inversion (malformed triangles). We propose a new energy function to address some of these issues.« less

Public health triangulation: approach and application to synthesizing data to understand national and local HIV epidemics.

PubMed

Rutherford, George W; McFarland, William; Spindler, Hilary; White, Karen; Patel, Sadhna V; Aberle-Grasse, John; Sabin, Keith; Smith, Nathan; Taché, Stephanie; Calleja-Garcia, Jesus M; Stoneburner, Rand L

2010-07-29

Public health triangulation is a process for reviewing, synthesising and interpreting secondary data from multiple sources that bear on the same question to make public health decisions. It can be used to understand the dynamics of HIV transmission and to measure the impact of public health programs. While traditional intervention research and meta-analysis would be ideal sources of information for public health decision making, they are infrequently available, and often decisions can be based only on surveillance and survey data. The process involves examination of a wide variety of data sources and both biological, behavioral and program data and seeks input from stakeholders to formulate meaningful public health questions. Finally and most importantly, it uses the results to inform public health decision-making. There are 12 discrete steps in the triangulation process, which included identification and assessment of key questions, identification of data sources, refining questions, gathering data and reports, assessing the quality of those data and reports, formulating hypotheses to explain trends in the data, corroborating or refining working hypotheses, drawing conclusions, communicating results and recommendations and taking public health action. Triangulation can be limited by the quality of the original data, the potentials for ecological fallacy and "data dredging" and reproducibility of results. Nonetheless, we believe that public health triangulation allows for the interpretation of data sets that cannot be analyzed using meta-analysis and can be a helpful adjunct to surveillance, to formal public health intervention research and to monitoring and evaluation, which in turn lead to improved national strategic planning and resource allocation.

Spectral triangulation: a 3D method for locating single-walled carbon nanotubes in vivo

NASA Astrophysics Data System (ADS)

Lin, Ching-Wei; Bachilo, Sergei M.; Vu, Michael; Beckingham, Kathleen M.; Bruce Weisman, R.

2016-05-01

Nanomaterials with luminescence in the short-wave infrared (SWIR) region are of special interest for biological research and medical diagnostics because of favorable tissue transparency and low autofluorescence backgrounds in that region. Single-walled carbon nanotubes (SWCNTs) show well-known sharp SWIR spectral signatures and therefore have potential for noninvasive detection and imaging of cancer tumours, when linked to selective targeting agents such as antibodies. However, such applications face the challenge of sensitively detecting and localizing the source of SWIR emission from inside tissues. A new method, called spectral triangulation, is presented for three dimensional (3D) localization using sparse optical measurements made at the specimen surface. Structurally unsorted SWCNT samples emitting over a range of wavelengths are excited inside tissue phantoms by an LED matrix. The resulting SWIR emission is sampled at points on the surface by a scanning fibre optic probe leading to an InGaAs spectrometer or a spectrally filtered InGaAs avalanche photodiode detector. Because of water absorption, attenuation of the SWCNT fluorescence in tissues is strongly wavelength-dependent. We therefore gauge the SWCNT-probe distance by analysing differential changes in the measured SWCNT emission spectra. SWCNT fluorescence can be clearly detected through at least 20 mm of tissue phantom, and the 3D locations of embedded SWCNT test samples are found with sub-millimeter accuracy at depths up to 10 mm. Our method can also distinguish and locate two embedded SWCNT sources at distinct positions.Nanomaterials with luminescence in the short-wave infrared (SWIR) region are of special interest for biological research and medical diagnostics because of favorable tissue transparency and low autofluorescence backgrounds in that region. Single-walled carbon nanotubes (SWCNTs) show well-known sharp SWIR spectral signatures and therefore have potential for noninvasive detection and imaging of cancer tumours, when linked to selective targeting agents such as antibodies. However, such applications face the challenge of sensitively detecting and localizing the source of SWIR emission from inside tissues. A new method, called spectral triangulation, is presented for three dimensional (3D) localization using sparse optical measurements made at the specimen surface. Structurally unsorted SWCNT samples emitting over a range of wavelengths are excited inside tissue phantoms by an LED matrix. The resulting SWIR emission is sampled at points on the surface by a scanning fibre optic probe leading to an InGaAs spectrometer or a spectrally filtered InGaAs avalanche photodiode detector. Because of water absorption, attenuation of the SWCNT fluorescence in tissues is strongly wavelength-dependent. We therefore gauge the SWCNT-probe distance by analysing differential changes in the measured SWCNT emission spectra. SWCNT fluorescence can be clearly detected through at least 20 mm of tissue phantom, and the 3D locations of embedded SWCNT test samples are found with sub-millimeter accuracy at depths up to 10 mm. Our method can also distinguish and locate two embedded SWCNT sources at distinct positions. Electronic supplementary information (ESI) available: Details concerning instrumental design, experimental procedures, related experiments, and triangulation computations, plus a video showing operation of the scanner. See DOI: 10.1039/c6nr01376g

Gender in Motion: Developmental Changes in Students' Conceptualizations of Gender through Participation in a First-Year Seminar Course

ERIC Educational Resources Information Center

Walters, Andrew S.; Sylaska, Kateryna M.

2012-01-01

Students enrolled in a first-year seminar course focused on gender provided attitudinal and experiential responses at two points during the course: during the first week of class and during the last week of class. A qualitative-quantitative method using concurrent triangulation was used to investigate pre- and post-test responses to core concepts…

Coordinates of features on the Galilean satellites

NASA Technical Reports Server (NTRS)

Davies, M. E.; Katayama, F. Y.

1980-01-01

The coordinate systems of each of the Galilean satellites are defined and coordinates of features seen in the Voyager pictures of these satellites are presented. The control nets of the satellites were computed by means of single block analytical triangulations. The normal equations were solved by the conjugate iterative method which is convenient and which converges rapidly as the initial estimates of the parameters are very good.

Workforce Diversity in Higher Education: Career Support Factors Influencing Ascendancy of African American Women to Senior-Level Positions

ERIC Educational Resources Information Center

Blackstone, Tondelaya K.

2011-01-01

The focus of this study was how knowledge of the barriers to advancement for African American women (AAW) and key career support factors (KCSFs) influence the career advancement of African American women (AAW) to senior-level positions in higher education. The research method for this study consisted of the triangulation of evidence from multiple…

Examining Perceptions of Administrators, Teachers, Parents, and Community Residents about Advantages and Disadvantages of Consolidating Two High Schools in a School District in Central Pennsylvania

ERIC Educational Resources Information Center

Ackell, Robert J.

2013-01-01

This mixed methods triangulation approach examined the perceptions of administrators, teachers, parents, and community residents about a consideration of a secondary school consolidation in a school district in central Pennsylvania. These groups are referred to as "stakeholders" in this study. The purpose of this research was to develop…

First Year Students in a Foreign Fabric: A Triangulation Study on Facebook as a Method of Coping

ERIC Educational Resources Information Center

Tilton, Shane

2012-01-01

As American high school seniors graduate and prepare to attend college, these students must change in order to adapt to the new rituals that higher education presents. Teens, for the most part, leave their family structure and their normal everyday routines to pursue a degree and a chance for a good paying job. However, these students can be…

L1 Use in EFL Classes with English-Only Policy: Insights from Triangulated Data

ERIC Educational Resources Information Center

Sa'd, Seyyed Hatam Tamimi; Qadermazi, Zohre

2015-01-01

This study examines the role of the use of the L1 in EFL classes from the perspective of EFL learners. The triangulated data were collected using class observations, focus group semi-structured interviews and the learners' written reports of their perceptions and attitudes in a purpose-designed questionnaire. The participants consisted of sixty…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J; Nguyen, D; O’Brien, R

Purpose: Kilovoltage intrafraction monitoring (KIM) scheme has been successfully used to simultaneously monitor 3D tumor motion during radiotherapy. Recently, an iterative closest point (ICP) algorithm was implemented in KIM to also measure rotations about three axes, enabling real-time tracking of tumor motion in six degrees-of-freedom (DoF). This study aims to evaluate the accuracy of the six DoF motion estimates of KIM by comparing it with the corresponding motion (i) measured by the Calypso; and (ii) derived from kV/MV triangulation. Methods: (i) Various motions (static and dynamic) were applied to a CIRS phantom with three embedded electromagnetic transponders (Calypso Medical) usingmore » a 5D motion platform (HexaMotion) and a rotating treatment couch while both KIM and Calypso were used to concurrently track the phantom motion in six DoF. (ii) KIM was also used to retrospectively estimate six DoF motion from continuous sets of kV projections of a prostate, implanted with three gold fiducial markers (2 patients with 80 fractions in total), acquired during the treatment. Corresponding motion was obtained from kV/MV triangulation using a closed form least squares method based on three markers’ positions. Only the frames where all three markers were present were used in the analysis. The mean differences between the corresponding motion estimates were calculated for each DoF. Results: Experimental results showed that the mean of absolute differences in six DoF phantom motion measured by Calypso and KIM were within 1.1° and 0.7 mm. kV/MV triangulation derived six DoF prostate tumor better agreed with KIM estimated motion with the mean (s.d.) difference of up to 0.2° (1.36°) and 0.2 (0.25) mm for rotation and translation, respectively. Conclusion: These results suggest that KIM can provide an accurate six DoF intrafraction tumor during radiotherapy.« less

Assessing the Accuracy of Adherence and Sexual Behaviour Data in the MDP301 Vaginal Microbicides Trial Using a Mixed Methods and Triangulation Model

PubMed Central

Pool, Robert; Montgomery, Catherine M.; Morar, Neetha S.; Mweemba, Oliver; Ssali, Agnes; Gafos, Mitzy; Lees, Shelley; Stadler, Jonathan; Nunn, Andrew; Crook, Angela; Hayes, Richard; McCormack, Sheena

2010-01-01

Background Accurate data on adherence and sexual behaviour are crucial in microbicide (and other HIV-related) research. In the absence of a “gold standard” the collection of such data relies largely on participant self-reporting. The Microbicides Development Programme has developed a mixed method/triangulation model for generating more accurate data on adherence and sexual behaviour. Methodology/Principal Findings Data were collected from a random subsample of 725 women using structured case record form (CRF) interviews, coital diaries (CD) and in-depth interviews (IDI). Returned used and unused gel applicators were counted and additional data collected through focus group discussions and ethnography. The model is described in detail in a companion paper [1]. When CRF, CD and IDI are compared there is some inconsistency with regard to reporting of sexual behaviour, gel or condom use in more than half. Inaccuracies are least prevalent in the IDI and most prevalent in the CRF, where participants tend to under-report frequency of sex and gel and condom use. Women reported more sex, gel and condom use than their partners. IDI data on adherence match the applicator-return data more closely than the CRF. The main reasons for inaccuracies are participants forgetting, interviewer error, desirability bias, problems with the definition and delineation of key concepts (e.g. “sex act”). Most inaccuracies were unintentional and could be rectified during data collection. Conclusions/Significance The CRF – the main source of self-report data on behaviour and adherence in many studies – was the least accurate with regard to measuring sexual behaviour, gel and condom use. This has important implications for the use of structured questionnaires for the collection of data on sexual behaviour and adherence. Integrating in-depth interviews and triangulation into clinical trials could increase the richness and accuracy of behavioural and adherence data. PMID:20657774

Thermodynamic free energy methods to investigate shape transitions in bilayer membranes.

PubMed

Ramakrishnan, N; Tourdot, Richard W; Radhakrishnan, Ravi

2016-06-01

The conformational free energy landscape of a system is a fundamental thermodynamic quantity of importance particularly in the study of soft matter and biological systems, in which the entropic contributions play a dominant role. While computational methods to delineate the free energy landscape are routinely used to analyze the relative stability of conformational states, to determine phase boundaries, and to compute ligand-receptor binding energies its use in problems involving the cell membrane is limited. Here, we present an overview of four different free energy methods to study morphological transitions in bilayer membranes, induced either by the action of curvature remodeling proteins or due to the application of external forces. Using a triangulated surface as a model for the cell membrane and using the framework of dynamical triangulation Monte Carlo, we have focused on the methods of Widom insertion, thermodynamic integration, Bennett acceptance scheme, and umbrella sampling and weighted histogram analysis. We have demonstrated how these methods can be employed in a variety of problems involving the cell membrane. Specifically, we have shown that the chemical potential, computed using Widom insertion, and the relative free energies, computed using thermodynamic integration and Bennett acceptance method, are excellent measures to study the transition from curvature sensing to curvature inducing behavior of membrane associated proteins. The umbrella sampling and WHAM analysis has been used to study the thermodynamics of tether formation in cell membranes and the quantitative predictions of the computational model are in excellent agreement with experimental measurements. Furthermore, we also present a method based on WHAM and thermodynamic integration to handle problems related to end-point-catastrophe that are common in most free energy methods.

Basic research and data analysis for the National Geodetic Satellite Program

NASA Technical Reports Server (NTRS)

1972-01-01

Investigations of triangulation nets and scaling are reported. Adjustment of the BC-4 worldwide geometric satellite triangulation net is described, along with procedures for correcting type II data and the contents of magnetic tapes containing data from the Pageos network. Computational steps for the further reduction of partially reduced satellite image plate coordinates are outlined. The problem of improving existing triangulation systems by means of satellite super-control points was studied. The SAO-69 geometric solution was scaled with C-band radar data, resulting in SAO and C-band adjustment compatible with one another in the Western Hemisphere. The North America solution NA-6, obtained from GEOS 1 data, was readjusted with new heights as constraints on all 30 optical stations and is referred to as the NA-8 solution.

3D change detection at street level using mobile laser scanning point clouds and terrestrial images

NASA Astrophysics Data System (ADS)

Qin, Rongjun; Gruen, Armin

2014-04-01

Automatic change detection and geo-database updating in the urban environment are difficult tasks. There has been much research on detecting changes with satellite and aerial images, but studies have rarely been performed at the street level, which is complex in its 3D geometry. Contemporary geo-databases include 3D street-level objects, which demand frequent data updating. Terrestrial images provides rich texture information for change detection, but the change detection with terrestrial images from different epochs sometimes faces problems with illumination changes, perspective distortions and unreliable 3D geometry caused by the lack of performance of automatic image matchers, while mobile laser scanning (MLS) data acquired from different epochs provides accurate 3D geometry for change detection, but is very expensive for periodical acquisition. This paper proposes a new method for change detection at street level by using combination of MLS point clouds and terrestrial images: the accurate but expensive MLS data acquired from an early epoch serves as the reference, and terrestrial images or photogrammetric images captured from an image-based mobile mapping system (MMS) at a later epoch are used to detect the geometrical changes between different epochs. The method will automatically mark the possible changes in each view, which provides a cost-efficient method for frequent data updating. The methodology is divided into several steps. In the first step, the point clouds are recorded by the MLS system and processed, with data cleaned and classified by semi-automatic means. In the second step, terrestrial images or mobile mapping images at a later epoch are taken and registered to the point cloud, and then point clouds are projected on each image by a weighted window based z-buffering method for view dependent 2D triangulation. In the next step, stereo pairs of the terrestrial images are rectified and re-projected between each other to check the geometrical consistency between point clouds and stereo images. Finally, an over-segmentation based graph cut optimization is carried out, taking into account the color, depth and class information to compute the changed area in the image space. The proposed method is invariant to light changes, robust to small co-registration errors between images and point clouds, and can be applied straightforwardly to 3D polyhedral models. This method can be used for 3D street data updating, city infrastructure management and damage monitoring in complex urban scenes.

Real-time 3D visualization of the thoraco-abdominal surface during breathing with body movement and deformation extraction.

PubMed

Povšič, K; Jezeršek, M; Možina, J

2015-07-01

Real-time 3D visualization of the breathing displacements can be a useful diagnostic tool in order to immediately observe the most active regions on the thoraco-abdominal surface. The developed method is capable of separating non-relevant torso movement and deformations from the deformations that are solely related to breathing. This makes it possible to visualize only the breathing displacements. The system is based on the structured laser triangulation principle, with simultaneous spatial and color data acquisition of the thoraco-abdominal region. Based on the tracking of the attached passive markers, the torso movement and deformation is compensated using rigid and non-rigid transformation models on the three-dimensional (3D) data. The total time of 3D data processing together with visualization equals 20 ms per cycle.In vitro verification of the rigid movement extraction was performed using the iterative closest point algorithm as a reference. Furthermore, a volumetric evaluation on a live subject was performed to establish the accuracy of the rigid and non-rigid model. The root mean square deviation between the measured and the reference volumes shows an error of  ±0.08 dm(3) for rigid movement extraction. Similarly, the error was calculated to be  ±0.02 dm(3) for torsional deformation extraction and  ±0.11 dm(3) for lateral bending deformation extraction. The results confirm that during the torso movement and deformation, the proposed method is sufficiently accurate to visualize only the displacements related to breathing. The method can be used, for example, during the breathing exercise on an indoor bicycle or a treadmill.

Triangulating case-finding tools for patient safety surveillance: a cross-sectional case study of puncture/laceration.

PubMed

Taylor, Jennifer A; Gerwin, Daniel; Morlock, Laura; Miller, Marlene R

2011-12-01

To evaluate the need for triangulating case-finding tools in patient safety surveillance. This study applied four case-finding tools to error-associated patient safety events to identify and characterise the spectrum of events captured by these tools, using puncture or laceration as an example for in-depth analysis. Retrospective hospital discharge data were collected for calendar year 2005 (n=48,418) from a large, urban medical centre in the USA. The study design was cross-sectional and used data linkage to identify the cases captured by each of four case-finding tools. Three case-finding tools (International Classification of Diseases external (E) and nature (N) of injury codes, Patient Safety Indicators (PSI)) were applied to the administrative discharge data to identify potential patient safety events. The fourth tool was Patient Safety Net, a web-based voluntary patient safety event reporting system. The degree of mutual exclusion among detection methods was substantial. For example, when linking puncture or laceration on unique identifiers, out of 447 potential events, 118 were identical between PSI and E-codes, 152 were identical between N-codes and E-codes and 188 were identical between PSI and N-codes. Only 100 events that were identified by PSI, E-codes and N-codes were identical. Triangulation of multiple tools through data linkage captures potential patient safety events most comprehensively. Existing detection tools target patient safety domains differently, and consequently capture different occurrences, necessitating the integration of data from a combination of tools to fully estimate the total burden.

Social and Emotional Learning Competencies and Cross-Thematic Curriculum-Related Skills of Greek Students: A Multifactorial and Triangulation Analysis

ERIC Educational Resources Information Center

Tsolou, Olympia; Margaritis, Vasileios

2013-01-01

The cross-thematic curriculum (CTC) for school education has recently been implemented so that the quality of the Greek educational system is improved. This study aimed at assessing social and emotional learning competencies and CTC-related skills of 541 Greek students aged 11-13. Data triangulation was also used for validating these findings,…

Keys to Successful Implementation and Sustainment of Managed Maintenance for Healthcare Facilities

DTIC Science & Technology

2004-03-23

second they involve studying those phenomena in all their complexity (Leedy and Ormrod, 2001). According to Denzin and Lincoln (1994), qualitative...people being studied (Leedy and Ormrod, 2001). Research Design Methodological Triangulation Denzin and Lincoln (1994) suggest because different...the setting. This dual view is refereed to as methodological triangulation ( Denzin and Lincoln , 1994). A research design develops a logical plan for

Insights from triangulation of two purchase choice elicitation methods to predict social decision making in healthcare.

PubMed

Whitty, Jennifer A; Rundle-Thiele, Sharyn R; Scuffham, Paul A

2012-03-01

Discrete choice experiments (DCEs) and the Juster scale are accepted methods for the prediction of individual purchase probabilities. Nevertheless, these methods have seldom been applied to a social decision-making context. To gain an overview of social decisions for a decision-making population through data triangulation, these two methods were used to understand purchase probability in a social decision-making context. We report an exploratory social decision-making study of pharmaceutical subsidy in Australia. A DCE and selected Juster scale profiles were presented to current and past members of the Australian Pharmaceutical Benefits Advisory Committee and its Economic Subcommittee. Across 66 observations derived from 11 respondents for 6 different pharmaceutical profiles, there was a small overall median difference of 0.024 in the predicted probability of public subsidy (p = 0.003), with the Juster scale predicting the higher likelihood. While consistency was observed at the extremes of the probability scale, the funding probability differed over the mid-range of profiles. There was larger variability in the DCE than Juster predictions within each individual respondent, suggesting the DCE is better able to discriminate between profiles. However, large variation was observed between individuals in the Juster scale but not DCE predictions. It is important to use multiple methods to obtain a complete picture of the probability of purchase or public subsidy in a social decision-making context until further research can elaborate on our findings. This exploratory analysis supports the suggestion that the mixed logit model, which was used for the DCE analysis, may fail to adequately account for preference heterogeneity in some contexts.

Revisiting the Quantitative-Qualitative Debate: Implications for Mixed-Methods Research

PubMed Central

SALE, JOANNA E. M.; LOHFELD, LYNNE H.; BRAZIL, KEVIN

2015-01-01

Health care research includes many studies that combine quantitative and qualitative methods. In this paper, we revisit the quantitative-qualitative debate and review the arguments for and against using mixed-methods. In addition, we discuss the implications stemming from our view, that the paradigms upon which the methods are based have a different view of reality and therefore a different view of the phenomenon under study. Because the two paradigms do not study the same phenomena, quantitative and qualitative methods cannot be combined for cross-validation or triangulation purposes. However, they can be combined for complementary purposes. Future standards for mixed-methods research should clearly reflect this recommendation. PMID:26523073

Some recent developments of the immersed interface method for flow simulation

NASA Astrophysics Data System (ADS)

Xu, Sheng

2017-11-01

The immersed interface method is a general methodology for solving PDEs subject to interfaces. In this talk, I will give an overview of some recent developments of the method toward the enhancement of its robustness for flow simulation. In particular, I will present with numerical results how to capture boundary conditions on immersed rigid objects, how to adopt interface triangulation in the method, and how to parallelize the method for flow with moving objects. With these developments, the immersed interface method can achieve accurate and efficient simulation of a flow involving multiple moving complex objects. Thanks to NSF for the support of this work under Grant NSF DMS 1320317.

The Holst spin foam model via cubulations

NASA Astrophysics Data System (ADS)

Baratin, Aristide; Flori, Cecilia; Thiemann, Thomas

2012-10-01

Spin foam models are an attempt at a covariant or path integral formulation of canonical loop quantum gravity. The construction of such models usually relies on the Plebanski formulation of general relativity as a constrained BF theory and is based on the discretization of the action on a simplicial triangulation, which may be viewed as an ultraviolet regulator. The triangulation dependence can be removed by means of group field theory techniques, which allows one to sum over all triangulations. The main tasks for these models are the correct quantum implementation of the Plebanski constraints, the existence of a semiclassical sector implementing additional ‘Regge-like’ constraints arising from simplicial triangulations and the definition of the physical inner product of loop quantum gravity via group field theory. Here we propose a new approach to tackle these issues stemming directly from the Holst action for general relativity, which is also a proper starting point for canonical loop quantum gravity. The discretization is performed by means of a ‘cubulation’ of the manifold rather than a triangulation. We give a direct interpretation of the resulting spin foam model as a generating functional for the n-point functions on the physical Hilbert space at finite regulator. This paper focuses on ideas and tasks to be performed before the model can be taken seriously. However, our analysis reveals some interesting features of this model: firstly, the structure of its amplitudes differs from the standard spin foam models. Secondly, the tetrad n-point functions admit a ‘Wick-like’ structure. Thirdly, the restriction to simple representations does not automatically occur—unless one makes use of the time gauge, just as in the classical theory.

THREED: A computer program for three dimensional transformation of coordinates. [in lunar photo triangulation mapping

NASA Technical Reports Server (NTRS)

Wong, K. W.

1974-01-01

Program THREED was developed for the purpose of a research study on the treatment of control data in lunar phototriangulation. THREED is the code name of a computer program for performing absolute orientation by the method of three-dimensional projective transformation. It has the capability of performing complete error analysis on the computed transformation parameters as well as the transformed coordinates.

Exploring cognitive support use and preference by college students with TBI: A mixed-methods study.

PubMed

Brown, Jessica; Hux, Karen; Hey, Morgan; Murphy, Madeline

2017-01-01

Many college students with TBI rely on external strategies and supports to compensate for persistent memory, organization, and planning deficits that interfere with recalling and executing daily tasks. Practitioners know little, however, about the supports students with TBI choose for this purpose, the reasoning behind their choice, or preferred features of selected supports. The purpose of this study was to explore these issues. We collected and analyzed quantitative and qualitative data from eight college students with TBI for completion of a concurrent triangulation mixed-methods design. Data analysis included evaluation and triangulation of participant demographic information, survey responses about persistent post-injury symptoms, transcripts from semi-structured interviews about cognitive support devices and strategies, and ranking results about specific compensatory tools. Results suggest that college students with TBI prefer high-tech external supports-sometimes with the addition of low-tech, paper supports-to assist them in managing daily tasks. This preference related to features of portability, accessibility, and automatic reminders. An electronic calendar was the most-preferred high-tech support, and a paper checklist was the most-preferred low-tech support. Rehabilitation professionals should consider implementing high-tech supports with preferred characteristics during treatment given the preferences of students with TBI and the consequent likelihood of their continued long-term use following reintegration to community settings.

Using Delaunay triangulation and Voronoi tessellation to predict the toxicities of binary mixtures containing hormetic compound

NASA Astrophysics Data System (ADS)

Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong

2017-03-01

Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures.

Plate refractive camera model and its applications

NASA Astrophysics Data System (ADS)

Huang, Longxiang; Zhao, Xu; Cai, Shen; Liu, Yuncai

2017-03-01

In real applications, a pinhole camera capturing objects through a planar parallel transparent plate is frequently employed. Due to the refractive effects of the plate, such an imaging system does not comply with the conventional pinhole camera model. Although the system is ubiquitous, it has not been thoroughly studied. This paper aims at presenting a simple virtual camera model, called a plate refractive camera model, which has a form similar to a pinhole camera model and can efficiently model refractions through a plate. The key idea is to employ a pixel-wise viewpoint concept to encode the refraction effects into a pixel-wise pinhole camera model. The proposed camera model realizes an efficient forward projection computation method and has some advantages in applications. First, the model can help to compute the caustic surface to represent the changes of the camera viewpoints. Second, the model has strengths in analyzing and rectifying the image caustic distortion caused by the plate refraction effects. Third, the model can be used to calibrate the camera's intrinsic parameters without removing the plate. Last but not least, the model contributes to putting forward the plate refractive triangulation methods in order to solve the plate refractive triangulation problem easily in multiviews. We verify our theory in both synthetic and real experiments.

Using Delaunay triangulation and Voronoi tessellation to predict the toxicities of binary mixtures containing hormetic compound

PubMed Central

Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong

2017-01-01

Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures. PMID:28287626

Derivation of formulas for root-mean-square errors in location, orientation, and shape in triangulation solution of an elongated object in space

NASA Technical Reports Server (NTRS)

Long, S. A. T.

1974-01-01

Formulas are derived for the root-mean-square (rms) displacement, slope, and curvature errors in an azimuth-elevation image trace of an elongated object in space, as functions of the number and spacing of the input data points and the rms elevation error in the individual input data points from a single observation station. Also, formulas are derived for the total rms displacement, slope, and curvature error vectors in the triangulation solution of an elongated object in space due to the rms displacement, slope, and curvature errors, respectively, in the azimuth-elevation image traces from different observation stations. The total rms displacement, slope, and curvature error vectors provide useful measure numbers for determining the relative merits of two or more different triangulation procedures applicable to elongated objects in space.

Evidence for asymptotic safety from lattice quantum gravity.

PubMed

Laiho, J; Coumbe, D

2011-10-14

We calculate the spectral dimension for nonperturbative quantum gravity defined via Euclidean dynamical triangulations. We find that it runs from a value of ∼3/2 at short distance to ∼4 at large distance scales, similar to results from causal dynamical triangulations. We argue that the short-distance value of 3/2 for the spectral dimension may resolve the tension between asymptotic safety and the holographic principle.

Triangulation of written assessments from patients, teachers and students: useful for students and teachers?

PubMed

Gran, Sarah Frandsen; Braend, Anja Maria; Lindbaek, Morten

2010-01-01

Many medical students in general practice clerkships experience lack of observation-based feedback. The StudentPEP project combined written feedback from patients, observing teachers and students. This study analyzes the perceived usefulness of triangulated written feedback. A total of 71 general practitioners and 79 medical students at the University of Oslo completed project evaluation forms after a 6-week clerkship. A principal component analysis was performed to find structures within the questionnaire. Regression analysis was performed regarding students' answers to whether StudentPEP was worthwhile. Free-text answers were analyzed qualitatively. Student and teacher responses were mixed within six subscales, with highest agreement on 'Teachers oral and written feedback' and 'Attitude to patient evaluation'. Fifty-four per cent of the students agreed that the triangulation gave concrete feedback on their weaknesses, and 59% valued the teachers' feedback provided. Two statements regarding the teacher's attitudes towards StudentPEP were significantly associated with the student's perception of worthwhileness. Qualitative analysis showed that patient evaluations were encouraging or distrusted. Some students thought that StudentPEP ensured observation and feedback. The patient evaluations increased the students' awareness of the patient perspective. A majority of the students considered the triangulated written feedback beneficial, although time-consuming. The teacher's attitudes strongly influenced how the students perceived the usefulness of StudentPEP.

Replicas in Cultural Heritage: 3d Printing and the Museum Experience

NASA Astrophysics Data System (ADS)

Ballarin, M.; Balletti, C.; Vernier, P.

2018-05-01

3D printing has seen a recent massive diffusion for several applications, not least the field of Cultural Heritage. Being used for different purposes, such as study, analysis, conservation or access in museum exhibitions, 3D printed replicas need to undergo a process of validation also in terms of metrical precision and accuracy. The Laboratory of Photogrammetry of Iuav University of Venice has started several collaborations with Italian museum institutions firstly for the digital acquisition and then for the physical reproduction of objects of historical and artistic interest. The aim of the research is to analyse the metric characteristics of the printed model in relation to the original data, and to optimize the process that from the survey leads to the physical representation of an object. In fact, this could be acquired through different methodologies that have different precisions (multi-image photogrammetry, TOF laser scanner, triangulation based laser scanner), and it always involves a long processing phase. It should not be forgotten that the digital data have to undergo a series of simplifications, which, on one hand, eliminate the noise introduced by the acquisition process, but on the other one, they can lead to discrepancies between the physical copy and the original geometry. In this paper we will show the results obtained on a small archaeological find that was acquired and reproduced for a museum exhibition intended for blind and partially sighted people.

Optical radar-based device for measuring automobile belt displacement in real time

NASA Astrophysics Data System (ADS)

Brennan, Brian W.; Gentile, John R.

1999-02-01

Ford Motor Company had a requirement to measure fan belt vibration on their 4.6 liter Cobra-Mustang engine. While this sensor was to be used in the laboratory, it would also be used for field testing of this engine. The general operation temperature was -40 to 120 degrees C, but there was an engine 'soak-back' requirement of up to 200 degrees C. The vibration requirement was 3g continuous at 10 Hz with 20g shock. Humidity was 0-95 percent. Without active cooling, the temperature environment eliminated engine mounted electronics and with it some more common approaches such as laser triangulation based sensing. A laser radar concept was developed which features remotely located electronics, fiber optic delivery and return of the signal and an engine mounted optic head. The three lens design of the receive optics is a compromise choice designed to maximize power at the receiver over the full travel of the belt. The electronic scheme consists of a time-to-amplitude converter based on a precise time interval derived from the phase difference of logic level pulse trains which in turn are formed by the 'exclusive O Ring' of the transmit and receive pulses. In practice, a 10 MHz pulse train is transmitted to the vibrating belt which coupled with some fast electronics results in about 1 0.1 mm resolution, sufficient for this application.

Brain segmentation and the generation of cortical surfaces

NASA Technical Reports Server (NTRS)

Joshi, M.; Cui, J.; Doolittle, K.; Joshi, S.; Van Essen, D.; Wang, L.; Miller, M. I.

1999-01-01

This paper describes methods for white matter segmentation in brain images and the generation of cortical surfaces from the segmentations. We have developed a system that allows a user to start with a brain volume, obtained by modalities such as MRI or cryosection, and constructs a complete digital representation of the cortical surface. The methodology consists of three basic components: local parametric modeling and Bayesian segmentation; surface generation and local quadratic coordinate fitting; and surface editing. Segmentations are computed by parametrically fitting known density functions to the histogram of the image using the expectation maximization algorithm [DLR77]. The parametric fits are obtained locally rather than globally over the whole volume to overcome local variations in gray levels. To represent the boundary of the gray and white matter we use triangulated meshes generated using isosurface generation algorithms [GH95]. A complete system of local parametric quadratic charts [JWM+95] is superimposed on the triangulated graph to facilitate smoothing and geodesic curve tracking. Algorithms for surface editing include extraction of the largest closed surface. Results for several macaque brains are presented comparing automated and hand surface generation. Copyright 1999 Academic Press.

Manipulatives Implementation For Supporting Learning Of Mathematics For Prospective Teachers

NASA Astrophysics Data System (ADS)

Sulistyaningsih, D.; Mawarsari, V. D.; Hidayah, I.; Dwijanto

2017-04-01

Manipulatives are needed by teachers to facilitate students understand of mathematics which is abstract. As a prospective mathematics teacher, the student must have good skills in making manipulatives. Aims of this study is to describe the implementation of learning courses of manipulative workshop in mathematics education courses by lecturer at Universitas Muhammadiyah Semarang which includes the preparation of learning, general professional ability, the professional capacity specifically, ability of self-development, development class managing, planning and implementation of learning, a way of delivering the material, and evaluation of learning outcomes. Data collection techniques used were questionnaires, interviews, and observation. The research instrument consisted of a questionnaire sheet, sheet observation and interview guides. Validity is determined using data triangulation and triangulation methods. Data were analyzed using an interactive model. The results showed that the average value of activities in preparation for learning, fosters capabilities of general professional, specialized professional, self-development, manage the classroom, implementing the learning, how to deliver the material, and how to evaluate learning outcomes are 79%, 73%, 67%, 75%, 83%, 72%, 64%, and 54%, respectively

Parallel Processing and Scientific Applications

DTIC Science & Technology

1992-11-30

Lattice QCD Calculations on the Connection Machine), SIAM News 24, 1 (May 1991) 5. C. F. Baillie and D. A. Johnston, Crumpling Dynamically Triangulated...hypercubic lattice ; in the second, the surface is randomly triangulated once at the beginning of the simulation; and in the third the random...Sharpe, QCD with Dynamical Wilson Fermions 1I, Phys. Rev. D44, 3272 (1991), 8. R. Gupta and C. F. Baillie, Critical Behavior of the 2D XY Model, Phys

Application of Stereo Vision to the Reconnection Scaling Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klarenbeek, Johnny; Sears, Jason A.; Gao, Kevin W.

The measurement and simulation of the three-dimensional structure of magnetic reconnection in astrophysical and lab plasmas is a challenging problem. At Los Alamos National Laboratory we use the Reconnection Scaling Experiment (RSX) to model 3D magnetohydrodynamic (MHD) relaxation of plasma filled tubes. These magnetic flux tubes are called flux ropes. In RSX, the 3D structure of the flux ropes is explored with insertable probes. Stereo triangulation can be used to compute the 3D position of a probe from point correspondences in images from two calibrated cameras. While common applications of stereo triangulation include 3D scene reconstruction and robotics navigation, wemore » will investigate the novel application of stereo triangulation in plasma physics to aid reconstruction of 3D data for RSX plasmas. Several challenges will be explored and addressed, such as minimizing 3D reconstruction errors in stereo camera systems and dealing with point correspondence problems.« less

Interactive Display of Surfaces Using Subdivision Surfaces and Wavelets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duchaineau, M A; Bertram, M; Porumbescu, S

2001-10-03

Complex surfaces and solids are produced by large-scale modeling and simulation activities in a variety of disciplines. Productive interaction with these simulations requires that these surfaces or solids be viewable at interactive rates--yet many of these surfaced solids can contain hundreds of millions of polygondpolyhedra. Interactive display of these objects requires compression techniques to minimize storage, and fast view-dependent triangulation techniques to drive the graphics hardware. In this paper, we review recent advances in subdivision-surface wavelet compression and optimization that can be used to provide a framework for both compression and triangulation. These techniques can be used to produce suitablemore » approximations of complex surfaces of arbitrary topology, and can be used to determine suitable triangulations for display. The techniques can be used in a variety of applications in computer graphics, computer animation and visualization.« less

Robot Guidance Using Machine Vision Techniques in Industrial Environments: A Comparative Review.

PubMed

Pérez, Luis; Rodríguez, Íñigo; Rodríguez, Nuria; Usamentiaga, Rubén; García, Daniel F

2016-03-05

In the factory of the future, most of the operations will be done by autonomous robots that need visual feedback to move around the working space avoiding obstacles, to work collaboratively with humans, to identify and locate the working parts, to complete the information provided by other sensors to improve their positioning accuracy, etc. Different vision techniques, such as photogrammetry, stereo vision, structured light, time of flight and laser triangulation, among others, are widely used for inspection and quality control processes in the industry and now for robot guidance. Choosing which type of vision system to use is highly dependent on the parts that need to be located or measured. Thus, in this paper a comparative review of different machine vision techniques for robot guidance is presented. This work analyzes accuracy, range and weight of the sensors, safety, processing time and environmental influences. Researchers and developers can take it as a background information for their future works.

Earth's gravity field to the eighteenth degree and geocentric coordinates for 104 stations from satellite and terrestrial data

NASA Technical Reports Server (NTRS)

Gaposchkin, E. M.

1973-01-01

Geodetic parameters describing the earth's gravity field and the positions of satellite-tracking stations in a geocentric reference frame were computed. These parameters were estimated by means of a combination of five different types of data: routine and simultaneous satellite observations, observations of deep-space probes, measurements of terrestrial gravity, and surface-triangulation data. The combination gives better parameters than does any subset of data types. The dynamic solution used precision-reduced Baker-Nunn observations and laser range data of 25 satellites. Data from the 49-station National Oceanic and Atmospheric Administration BC-4 network, the 19-station Smithsonian Astrophysical Observatory Baker-Nunn network, and independent camera stations were employed in the geometrical solution. Data from the tracking of deep-space probes were converted to relative longitudes and distances to the earth's axis of rotation of the tracking stations. Surface-gravity data in the form of 550-km squares were derived from 19,328 1 deg X 1 deg mean gravity anomalies.

3D scanning characteristics of an amorphous silicon position sensitive detector array system.

PubMed

Contreras, Javier; Gomes, Luis; Filonovich, Sergej; Correia, Nuno; Fortunato, Elvira; Martins, Rodrigo; Ferreira, Isabel

2012-02-13

The 3D scanning electro-optical characteristics of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) were analyzed. The system was mounted on a platform for imaging 3D objects using the triangulation principle with a sheet-of-light laser. New obtained results reveal a minimum possible gap or simulated defect detection of approximately 350 μm. Furthermore, a first study of the angle for 3D scanning was also performed, allowing for a broad range of angles to be used in the process. The relationship between the scanning angle of the incident light onto the object and the image displacement distance on the sensor was determined for the first time in this system setup. Rendering of 3D object profiles was performed at a significantly higher number of frames than in the past and was possible for an incident light angle range of 15 ° to 85 °.

Robot Guidance Using Machine Vision Techniques in Industrial Environments: A Comparative Review

PubMed Central

Pérez, Luis; Rodríguez, Íñigo; Rodríguez, Nuria; Usamentiaga, Rubén; García, Daniel F.

2016-01-01

In the factory of the future, most of the operations will be done by autonomous robots that need visual feedback to move around the working space avoiding obstacles, to work collaboratively with humans, to identify and locate the working parts, to complete the information provided by other sensors to improve their positioning accuracy, etc. Different vision techniques, such as photogrammetry, stereo vision, structured light, time of flight and laser triangulation, among others, are widely used for inspection and quality control processes in the industry and now for robot guidance. Choosing which type of vision system to use is highly dependent on the parts that need to be located or measured. Thus, in this paper a comparative review of different machine vision techniques for robot guidance is presented. This work analyzes accuracy, range and weight of the sensors, safety, processing time and environmental influences. Researchers and developers can take it as a background information for their future works. PMID:26959030

In-situ position and vibration measurement of rough surfaces using laser Doppler distance sensors

NASA Astrophysics Data System (ADS)

Czarske, J.; Pfister, T.; Günther, P.; Büttner, L.

2009-06-01

In-situ measurement of distances and shapes as well as dynamic deformations and vibrations of fast moving and especially rotating objects, such as gear shafts and turbine blades, is an important task at process control. We recently developed a laser Doppler distance frequency sensor, employing two superposed fan-shaped interference fringe systems with contrary fringe spacing gradients. Via two Doppler frequency evaluations the non-incremental position (i.e. distance) and the tangential velocity of rotating bodies are determined simultaneously. The distance uncertainty is in contrast to e.g. triangulation in principle independent of the object velocity. This unique feature allows micrometer resolutions of fast moved rough surfaces. The novel sensor was applied at turbo machines in order to control the tip clearance. The measurements at a transonic centrifugal compressor were performed during operation at up to 50,000 rpm, i.e. 586 m/s velocity of the blade tips. Due to the operational conditions such as temperatures of up to 300 °C, a flexible and robust measurement system with a passive fiber-coupled sensor, using diffractive optics, has been realized. Since the tip clearance of individual blades could be temporally resolved an analysis of blade vibrations was possible. A Fourier transformation of the blade distances results in an average period of 3 revolutions corresponding to a frequency of 1/3 of the rotary frequency. Additionally, a laser Doppler distance sensor using two tilted fringe systems and phase evaluation will be presented. This phase sensor exhibits a minimum position resolution of σz = 140 nm. It allows precise in-situ shape measurements at grinding and turning processes.

Who do we think we are? Analysing the content and form of identity work in the English National Health Service.

PubMed

McDermott, Imelda; Checkland, Kath; Harrison, Stephen; Snow, Stephanie; Coleman, Anna

2013-01-01

The language used by National Health Service (NHS) "commissioning" managers when discussing their roles and responsibilities can be seen as a manifestation of "identity work", defined as a process of identifying. This paper aims to offer a novel approach to analysing "identity work" by triangulation of multiple analytical methods, combining analysis of the content of text with analysis of its form. Fairclough's discourse analytic methodology is used as a framework. Following Fairclough, the authors use analytical methods associated with Halliday's systemic functional linguistics. While analysis of the content of interviews provides some information about NHS Commissioners' perceptions of their roles and responsibilities, analysis of the form of discourse that they use provides a more detailed and nuanced view. Overall, the authors found that commissioning managers have a higher level of certainty about what commissioning is not rather than what commissioning is; GP managers have a high level of certainty of their identity as a GP rather than as a manager; and both GP managers and non-GP managers oscillate between multiple identities depending on the different situations they are in. This paper offers a novel approach to triangulation, based not on the usual comparison of multiple data sources, but rather based on the application of multiple analytical methods to a single source of data. This paper also shows the latent uncertainty about the nature of commissioning enterprise in the English NHS.

Validation of an acoustic location system to monitor Bornean orangutan (Pongo pygmaeus wurmbii) long calls.

PubMed

Spillmann, Brigitte; van Noordwijk, Maria A; Willems, Erik P; Mitra Setia, Tatang; Wipfli, Urs; van Schaik, Carel P

2015-07-01

The long call is an important vocal communication signal in the widely dispersed, semi-solitary orangutan. Long calls affect individuals' ranging behavior and mediate social relationships and regulate encounters between dispersed individuals in a dense rainforest. The aim of this study was to test the utility of an Acoustic Location System (ALS) for recording and triangulating the loud calls of free-living primates. We developed and validated a data extraction protocol for an ALS used to record wild orangutan males' long calls at the Tuanan field site (Central Kalimantan). We installed an ALS in a grid of 300 ha, containing 20 SM2+ recorders placed in a regular lattice at 500 m intervals, to monitor the distribution of calling males in the area. The validated system had the following main features: (i) a user-trained software algorithm (Song Scope) that reliably recognized orangutan long calls from sound files at distances up to 700 m from the nearest recorder, resulting in a total area of approximately 900 ha that could be monitored continuously; (ii) acoustic location of calling males up to 200 m outside the microphone grid, which meant that within an area of approximately 450 ha, call locations could be calculated through triangulation. The mean accuracy was 58 m, an error that is modest relative to orangutan mobility and average inter-individual distances. We conclude that an ALS is a highly effective method for detecting long-distance calls of wild primates and triangulating their position. In combination with conventional individual focal follow data, an ALS can greatly improve our knowledge of orangutans' social organization, and is readily adaptable for studying other highly vocal animals. © 2015 Wiley Periodicals, Inc.

Ortho-Rectification of Narrow Band Multi-Spectral Imagery Assisted by Dslr RGB Imagery Acquired by a Fixed-Wing Uas

NASA Astrophysics Data System (ADS)

Rau, J.-Y.; Jhan, J.-P.; Huang, C.-Y.

2015-08-01

Miniature Multiple Camera Array (MiniMCA-12) is a frame-based multilens/multispectral sensor composed of 12 lenses with narrow band filters. Due to its small size and light weight, it is suitable to mount on an Unmanned Aerial System (UAS) for acquiring high spectral, spatial and temporal resolution imagery used in various remote sensing applications. However, due to its wavelength range is only 10 nm that results in low image resolution and signal-to-noise ratio which are not suitable for image matching and digital surface model (DSM) generation. In the meantime, the spectral correlation among all 12 bands of MiniMCA images are low, it is difficult to perform tie-point matching and aerial triangulation at the same time. In this study, we thus propose the use of a DSLR camera to assist automatic aerial triangulation of MiniMCA-12 imagery and to produce higher spatial resolution DSM for MiniMCA12 ortho-image generation. Depending on the maximum payload weight of the used UAS, these two kinds of sensors could be collected at the same time or individually. In this study, we adopt a fixed-wing UAS to carry a Canon EOS 5D Mark2 DSLR camera and a MiniMCA-12 multi-spectral camera. For the purpose to perform automatic aerial triangulation between a DSLR camera and the MiniMCA-12, we choose one master band from MiniMCA-12 whose spectral range has overlap with the DSLR camera. However, all lenses of MiniMCA-12 have different perspective centers and viewing angles, the original 12 channels have significant band misregistration effect. Thus, the first issue encountered is to reduce the band misregistration effect. Due to all 12 MiniMCA lenses being frame-based, their spatial offsets are smaller than 15 cm and all images are almost 98% overlapped, we thus propose a modified projective transformation (MPT) method together with two systematic error correction procedures to register all 12 bands of imagery on the same image space. It means that those 12 bands of images acquired at the same exposure time will have same interior orientation parameters (IOPs) and exterior orientation parameters (EOPs) after band-to-band registration (BBR). Thus, in the aerial triangulation stage, the master band of MiniMCA-12 was treated as a reference channel to link with DSLR RGB images. It means, all reference images from the master band of MiniMCA-12 and all RGB images were triangulated at the same time with same coordinate system of ground control points (GCP). Due to the spatial resolution of RGB images is higher than the MiniMCA-12, the GCP can be marked on the RGB images only even they cannot be recognized on the MiniMCA images. Furthermore, a one meter gridded digital surface model (DSM) is created by the RGB images and applied to the MiniMCA imagery for ortho-rectification. Quantitative error analyses show that the proposed BBR scheme can achieve 0.33 pixels of average misregistration residuals length and the co-registration errors among 12 MiniMCA ortho-images and between MiniMCA and Canon RGB ortho-images are all less than 0.6 pixels. The experimental results demonstrate that the proposed method is robust, reliable and accurate for future remote sensing applications.

Radio triangulation - mapping the 3D position of the solar radio emission

NASA Astrophysics Data System (ADS)

Magdalenic, Jasmina

2016-04-01

Understanding the relative position of the sources of the radio emission and the associated solar eruptive phenomena (CME and the associated shock wave) has always been a challenge. While ground-based radio interferometer observations provide us with the 2D position information for the radio emission originating from the low corona (up to 2.5 Ro), this is not the case for the radio emission originating at larger heights. The radio triangulation measurements (also referred to as direction-finding or goniopolarimetric measurements) from two or more widely separated spacecraft can provide information on the 3D positions of the sources of the radio emission. This type of interplanetary radio observations are currently performed by STEREO WAVES and WIND WAVES instruments, providing a unique possibility for up to three simultaneous radio triangulations (using up to three different pairs of spacecraft). The recent results of the radio triangulation studies bring new insight into the causal relationship of the solar radio emission and CMEs. In this presentation I will discuss some of the most intriguing results on the source positions of: a) type III radio bursts indicating propagation of the fast electrons accelerated along the open field lines, b) type II radio bursts indicating interaction of the CME-driven shocks and other coronal structures e.g. streamers and c) type IV-like radio bursts possibly associated with CME-CME interaction.

Downhole Elemental Analysis with LIBS

NASA Technical Reports Server (NTRS)

Moreschini, Paolo; Zacny, Kris; Rickman, Doug

2011-01-01

In this paper we discuss a novel instrument, currently under development at Honeybee Robotics with SBIR funding from NASA. The device is designed to characterize elemental composition as a function of depth in non-terrestrial geological formations. The instrument consists of a miniaturized laser-induced breakdown spectrometer (LIBS) analyzer integrated in a 2" diameter drill string. While the drill provides subsurface access, the LIBS analyzer provides information on the elemental composition of the borehole wall. This instrument has a variety of space applications ranging from exploration of the Moon for which it was originally designed, to Mars, as well as a variety of terrestrial applications. Subsurface analysis is usually performed by sample acquisition through a drill or excavator, followed by sample preparation and subsequent sample presentation to an instrument or suite of instruments. An alternative approach consisting in bringing a miniaturized version of the instrument to the sample has many advantages over the traditional methodology, as it allows faster response, reduced probability of cross-contamination and a simplification in the sampling mechanisms. LIBS functions by focusing a high energy laser on a material inducing a plasma consisting of a small fraction of the material under analysis. Optical emission from the plasma, analyzed by a spectrometer, can be used to determine elemental composition. A triangulation sensor located in the sensor head determines the distance of the sensor from the borehole wall. An actuator modifies the position of the sensor accordingly, in order to compensate for changes due to the profile of the borehole walls. This is necessary because LIBS measurements are negatively affected by changes in the relative position of the focus of the laser with respect to the position of the sample (commonly referred to as the "lens to sample distance"). Profiling the borehole is done by adjusting the position of the sensor with a vertical stage; a second actuator at the top of the downhole probe allows radial scanning of the borehole. Analysis of iron and titanium in lunar simulant with LIBS was performed in air using the method of standard addition. The results for lunar simulant NU-LHT-2M show a value for the concentration of iron ranging between 2.29% and 3.05% depending on the atomic line selected. The accepted value for the sample analyzed is 2.83%, showing the capability for the system in development to provide qualitative and semi-quantitative analysis in real-time.

Research philosophy: towards an understanding.

PubMed

Crossan, Frank

2003-01-01

In this paper, Frank Crossan argues that the distinction between quantitative and qualitative philosophies and research methods is sometimes overstated, and that triangulation of methods in contemporary research is common. It is, therefore, important to understand the strengths and weaknesses of each approach, and this paper aims to provide the novice researcher with a basis for developing that understanding. A descriptive analysis of the philosophies of positivism and post-positivist thinking in relation to research methodology is presented both as an introduction to the philosophical basis of research, and as a sound basis from which to discuss the 'quantitative-qualitative' debate.

Low-power triggered data acquisition system and method

NASA Technical Reports Server (NTRS)

Champaigne, Kevin (Inventor); Sumners, Jonathan (Inventor)

2012-01-01

A low-power triggered data acquisition system and method utilizes low-powered circuitry, comparators, and digital logic incorporated into a miniaturized device interfaced with self-generating transducer sensor inputs to detect, identify and assess impact and damage to surfaces and structures wherein, upon the occurrence of a triggering event that produces a signal greater than a set threshold changes the comparator output and causes the system to acquire and store digital data representative of the incoming waveform on at least one triggered channel. The sensors may be disposed in an array to provide triangulation and location of the impact.

Inverse gravity modeling for depth varying density structures through genetic algorithm, triangulated facet representation, and switching routines

NASA Astrophysics Data System (ADS)

King, Thomas Steven

A hybrid gravity modeling method is developed to investigate the structure of sedimentary mass bodies. The method incorporates as constraints surficial basement/sediment contacts and topography of a mass target with a quadratically varying density distribution. The inverse modeling utilizes a genetic algorithm (GA) to scan a wide range of the solution space to determine initial models and the Marquardt-Levenberg (ML) nonlinear inversion to determine final models that meet pre-assigned misfit criteria, thus providing an estimate of model variability and uncertainty. The surface modeling technique modifies Delaunay triangulation by allowing individual facets to be manually constructed and non-convex boundaries to be incorporated into the triangulation scheme. The sedimentary body is represented by a set of uneven prisms and edge elements, comprised of tetrahedrons, capped by polyhedrons. Each underlying prism and edge element's top surface is located by determining its point of tangency with the overlying terrain. The remaining overlying mass is gravitationally evaluated and subtracted from the observation points. Inversion then proceeds in the usual sense, but on an irregular tiered surface with each element's density defined relative to their top surface. Efficiency is particularly important due to the large number of facets evaluated for surface representations and the many repeated element evaluations of the stochastic GA. The gravitation of prisms, triangular faceted polygons, and tetrahedrons can be formulated in different ways, either mathematically or by physical approximations, each having distinct characteristics, such as evaluation time, accuracy over various spatial ranges, and computational singularities. A decision tree or switching routine is constructed for each element by combining these characteristics into a single cohesive package that optimizes the computation for accuracy and speed while avoiding singularities. The GA incorporates a subspace technique and parameter dependency to maintain model smoothness during development, thus minimizing creating nonphysical models. The stochastic GA explores the solution space, producing a broad range of unbiased initial models, while the ML inversion is deterministic and thus quickly converges to the final model. The combination allows many solution models to be determined from the same observed data.

Discrete maximum principle for the P1 - P0 weak Galerkin finite element approximations

NASA Astrophysics Data System (ADS)

Wang, Junping; Ye, Xiu; Zhai, Qilong; Zhang, Ran

2018-06-01

This paper presents two discrete maximum principles (DMP) for the numerical solution of second order elliptic equations arising from the weak Galerkin finite element method. The results are established by assuming an h-acute angle condition for the underlying finite element triangulations. The mathematical theory is based on the well-known De Giorgi technique adapted in the finite element context. Some numerical results are reported to validate the theory of DMP.

RO1 Funding for Mixed Methods Research: Lessons learned from the Mixed-Method Analysis of Japanese Depression Project

PubMed Central

Arnault, Denise Saint; Fetters, Michael D.

2013-01-01

Mixed methods research has made significant in-roads in the effort to examine complex health related phenomenon. However, little has been published on the funding of mixed methods research projects. This paper addresses that gap by presenting an example of an NIMH funded project using a mixed methods QUAL-QUAN triangulation design entitled “The Mixed-Method Analysis of Japanese Depression.” We present the Cultural Determinants of Health Seeking model that framed the study, the specific aims, the quantitative and qualitative data sources informing the study, and overview of the mixing of the two studies. Finally, we examine reviewer's comments and our insights related to writing mixed method proposal successful for achieving RO1 level funding. PMID:25419196

Comparison Of Methods Used In Cartography For The Skeletonisation Of Areal Objects

NASA Astrophysics Data System (ADS)

Szombara, Stanisław

2015-12-01

The article presents a method that would compare skeletonisation methods for areal objects. The skeleton of an areal object, being its linear representation, is used, among others, in cartographic visualisation. The method allows us to compare between any skeletonisation methods in terms of the deviations of distance differences between the skeleton of the object and its border from one side and the distortions of skeletonisation from another. In the article, 5 methods were compared: Voronoi diagrams, densified Voronoi diagrams, constrained Delaunay triangulation, Straight Skeleton and Medial Axis (Transform). The results of comparison were presented on the example of several areal objects. The comparison of the methods showed that in all the analysed objects the Medial Axis (Transform) gives the smallest distortion and deviation values, which allows us to recommend it.

A note on statistical analysis of shape through triangulation of landmarks

PubMed Central

Rao, C. Radhakrishna

2000-01-01

In an earlier paper, the author jointly with S. Suryawanshi proposed statistical analysis of shape through triangulation of landmarks on objects. It was observed that the angles of the triangles are invariant to scaling, location, and rotation of objects. No distinction was made between an object and its reflection. The present paper provides the methodology of shape discrimination when reflection is also taken into account and makes suggestions for modifications to be made when some of the landmarks are collinear. PMID:10737780

Analyzing Hydro-Geomorphic Responses in Post-Fire Stream Channels with Terrestrial LiDAR

NASA Astrophysics Data System (ADS)

Nourbakhshbeidokhti, S.; Kinoshita, A. M.; Chin, A.

2015-12-01

Wildfires have potential to significantly alter soil properties and vegetation within watersheds. These alterations often contribute to accelerated erosion, runoff, and sediment transport in stream channels and hillslopes. This research applies repeated Terrestrial Laser Scanning (TLS) Light Detection and Ranging (LiDAR) to stream reaches within the Pike National Forest in Colorado following the 2012 Waldo Canyon Fire. These scans allow investigation of the relationship between sediment delivery and environmental characteristics such as precipitation, soil burn severity, and vegetation. Post-fire LiDAR images provide high resolution information of stream channel changes in eight reaches for three years (2012-2014). All images are processed with RiSCAN PRO to remove vegetation and triangulated and smoothed to create a Digital Elevation Model (DEM) with 0.1 m resolution. Study reaches with two or more successive DEM images are compared using a differencing method to estimate the volume of sediment erosion and deposition. Preliminary analysis of four channel reaches within Williams Canyon and Camp Creek yielded erosion estimates between 0.035 and 0.618 m3 per unit area. Deposition was estimated as 0.365 to 1.67 m3 per unit area. Reaches that experienced higher soil burn severity or larger rainfall events produced the greatest geomorphic changes. Results from LiDAR analyses can be incorporated into post-fire hydrologic models to improve estimates of runoff and sediment yield. These models will, in turn, provide guidance for water resources management and downstream hazards mitigation.

Comparative Analysis of Data Structures for Storing Massive Tins in a Dbms

NASA Astrophysics Data System (ADS)

Kumar, K.; Ledoux, H.; Stoter, J.

2016-06-01

Point cloud data are an important source for 3D geoinformation. Modern day 3D data acquisition and processing techniques such as airborne laser scanning and multi-beam echosounding generate billions of 3D points for simply an area of few square kilometers. With the size of the point clouds exceeding the billion mark for even a small area, there is a need for their efficient storage and management. These point clouds are sometimes associated with attributes and constraints as well. Storing billions of 3D points is currently possible which is confirmed by the initial implementations in Oracle Spatial SDO PC and the PostgreSQL Point Cloud extension. But to be able to analyse and extract useful information from point clouds, we need more than just points i.e. we require the surface defined by these points in space. There are different ways to represent surfaces in GIS including grids, TINs, boundary representations, etc. In this study, we investigate the database solutions for the storage and management of massive TINs. The classical (face and edge based) and compact (star based) data structures are discussed at length with reference to their structure, advantages and limitations in handling massive triangulations and are compared with the current solution of PostGIS Simple Feature. The main test dataset is the TIN generated from third national elevation model of the Netherlands (AHN3) with a point density of over 10 points/m2. PostgreSQL/PostGIS DBMS is used for storing the generated TIN. The data structures are tested with the generated TIN models to account for their geometry, topology, storage, indexing, and loading time in a database. Our study is useful in identifying what are the limitations of the existing data structures for storing massive TINs and what is required to optimise these structures for managing massive triangulations in a database.

Lattice gas simulations of dynamical geometry in two dimensions.

PubMed

Klales, Anna; Cianci, Donato; Needell, Zachary; Meyer, David A; Love, Peter J

2010-10-01

We present a hydrodynamic lattice gas model for two-dimensional flows on curved surfaces with dynamical geometry. This model is an extension to two dimensions of the dynamical geometry lattice gas model previously studied in one dimension. We expand upon a variation of the two-dimensional flat space Frisch-Hasslacher-Pomeau (FHP) model created by Frisch [Phys. Rev. Lett. 56, 1505 (1986)] and independently by Wolfram, and modified by Boghosian [Philos. Trans. R. Soc. London, Ser. A 360, 333 (2002)]. We define a hydrodynamic lattice gas model on an arbitrary triangulation whose flat space limit is the FHP model. Rules that change the geometry are constructed using the Pachner moves, which alter the triangulation but not the topology. We present results on the growth of the number of triangles as a function of time. Simulations show that the number of triangles grows with time as t(1/3), in agreement with a mean-field prediction. We also present preliminary results on the distribution of curvature for a typical triangulation in these simulations.

Coherent Structure Detection using Persistent Homology and other Topological Tools

NASA Astrophysics Data System (ADS)

Smith, Spencer; Roberts, Eric; Sindi, Suzanne; Mitchell, Kevin

2017-11-01

For non-autonomous, aperiodic fluid flows, coherent structures help organize the dynamics, much as invariant manifolds and periodic orbits do for autonomous or periodic systems. The prevalence of such flows in nature and industry has motivated many successful techniques for defining and detecting coherent structures. However, often these approaches require very fine trajectory data to reconstruct velocity fields and compute Cauchy-Green-tensor-related quantities. We use topological techniques to help detect coherent trajectory sets in relatively sparse 2D advection problems. More specifically, we have developed a homotopy-based algorithm, the ensemble-based topological entropy calculation (E-tec), which assigns to each edge in an initial triangulation of advected points a topologically forced lower bound on its future stretching rate. The triangulation and its weighted edges allow us to analyze flows using persistent homology. This topological data analysis tool detects clusters and loops in the triangulation that are robust in the presence of noise and in this case correspond to coherent trajectory sets.

The Local Discontinuous Galerkin Method for Time-Dependent Convection-Diffusion Systems

NASA Technical Reports Server (NTRS)

Cockburn, Bernardo; Shu, Chi-Wang

1997-01-01

In this paper, we study the Local Discontinuous Galerkin methods for nonlinear, time-dependent convection-diffusion systems. These methods are an extension of the Runge-Kutta Discontinuous Galerkin methods for purely hyperbolic systems to convection-diffusion systems and share with those methods their high parallelizability, their high-order formal accuracy, and their easy handling of complicated geometries, for convection dominated problems. It is proven that for scalar equations, the Local Discontinuous Galerkin methods are L(sup 2)-stable in the nonlinear case. Moreover, in the linear case, it is shown that if polynomials of degree k are used, the methods are k-th order accurate for general triangulations; although this order of convergence is suboptimal, it is sharp for the LDG methods. Preliminary numerical examples displaying the performance of the method are shown.

Optical microtopographic inspection of the surface of tooth subjected to stripping reduction

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Pereira, Pedro B.

2011-05-01

In orthodontics, the decreasing of tooth-size by reducing interproximal enamel surfaces (stripping) of teeth is a common procedure which allows dental alignment with minimal changes in the facial profile and no arch expansion. In order to achieve smooth surfaces, clinicians have been testing various methods and progressively improved this therapeutic technique. In order to evaluate the surface roughness of teeth subject to interproximal reduction through the five most commonly used methods, teeth were inspected by scanning electron microscopy and microtopographically measured using the optical active triangulation based microtopographer MICROTOP.06.MFC. The metrological procedure will be presented as well as the comparative results concluding on the most suitable tooth interproximal reduction method.

Geometric shapes inversion method of space targets by ISAR image segmentation

NASA Astrophysics Data System (ADS)

Huo, Chao-ying; Xing, Xiao-yu; Yin, Hong-cheng; Li, Chen-guang; Zeng, Xiang-yun; Xu, Gao-gui

2017-11-01

The geometric shape of target is an effective characteristic in the process of space targets recognition. This paper proposed a method of shape inversion of space target based on components segmentation from ISAR image. The Radon transformation, Hough transformation, K-means clustering, triangulation will be introduced into ISAR image processing. Firstly, we use Radon transformation and edge detection to extract space target's main body spindle and solar panel spindle from ISAR image. Then the targets' main body, solar panel, rectangular and circular antenna are segmented from ISAR image based on image detection theory. Finally, the sizes of every structural component are computed. The effectiveness of this method is verified using typical targets' simulation data.

Triangulated Proxy Reporting: a technique for improving how communication partners come to know people with severe cognitive impairment.

PubMed

Lyons, Gordon; De Bortoli, Tania; Arthur-Kelly, Michael

2017-09-01

This paper explains and demonstrates the pilot application of Triangulated Proxy Reporting (TPR); a practical technique for enhancing communication around people who have severe cognitive impairment (SCI). An introduction explains SCI and how this impacts on communication; and consequently on quality of care and quality of life. This is followed by an explanation of TPR and its origins in triangulation research techniques. An illustrative vignette explicates its utility and value in a group home for a resident with profound multiple disabilities. The Discussion and Conclusion sections propose the wider application of TPR for different cohorts of people with SCIs, their communication partners and service providers. TPR presents as a practical technique for enhancing communication interactions with people who have SCI. The paper demonstrates the potential of the technique for improving engagement amongst those with profound multiple disabilities, severe acquired brain injury and advanced dementia and their partners in and across different care settings. Implications for Rehabilitation Triangulated Proxy Reporting (TPR) shows potential to improve communications between people with severe cognitive impairments and their communication partners. TPR can lead to improved quality of care and quality of life for people with profound multiple disabilities, very advanced dementia and severe acquired brain injury, who otherwise are very difficult to support. TPR is a relatively simple and inexpensive technique that service providers can incorporate into practice to improving communications between clients with severe cognitive impairments, their carers and other support professionals.

RIACS

NASA Technical Reports Server (NTRS)

Oliger, Joseph

1997-01-01

Topics considered include: high-performance computing; cognitive and perceptual prostheses (computational aids designed to leverage human abilities); autonomous systems. Also included: development of a 3D unstructured grid code based on a finite volume formulation and applied to the Navier-stokes equations; Cartesian grid methods for complex geometry; multigrid methods for solving elliptic problems on unstructured grids; algebraic non-overlapping domain decomposition methods for compressible fluid flow problems on unstructured meshes; numerical methods for the compressible navier-stokes equations with application to aerodynamic flows; research in aerodynamic shape optimization; S-HARP: a parallel dynamic spectral partitioner; numerical schemes for the Hamilton-Jacobi and level set equations on triangulated domains; application of high-order shock capturing schemes to direct simulation of turbulence; multicast technology; network testbeds; supercomputer consolidation project.

Image matching for digital close-range stereo photogrammetry based on constraints of Delaunay triangulated network and epipolar-line

NASA Astrophysics Data System (ADS)

Zhang, K.; Sheng, Y. H.; Li, Y. Q.; Han, B.; Liang, Ch.; Sha, W.

2006-10-01

In the field of digital photogrammetry and computer vision, the determination of conjugate points in a stereo image pair, referred to as "image matching," is the critical step to realize automatic surveying and recognition. Traditional matching methods encounter some problems in the digital close-range stereo photogrammetry, because the change of gray-scale or texture is not obvious in the close-range stereo images. The main shortcoming of traditional matching methods is that geometric information of matching points is not fully used, which will lead to wrong matching results in regions with poor texture. To fully use the geometry and gray-scale information, a new stereo image matching algorithm is proposed in this paper considering the characteristics of digital close-range photogrammetry. Compared with the traditional matching method, the new algorithm has three improvements on image matching. Firstly, shape factor, fuzzy maths and gray-scale projection are introduced into the design of synthetical matching measure. Secondly, the topology connecting relations of matching points in Delaunay triangulated network and epipolar-line are used to decide matching order and narrow the searching scope of conjugate point of the matching point. Lastly, the theory of parameter adjustment with constraint is introduced into least square image matching to carry out subpixel level matching under epipolar-line constraint. The new algorithm is applied to actual stereo images of a building taken by digital close-range photogrammetric system. The experimental result shows that the algorithm has a higher matching speed and matching accuracy than pyramid image matching algorithm based on gray-scale correlation.

A FAST ITERATIVE METHOD FOR SOLVING THE EIKONAL EQUATION ON TRIANGULATED SURFACES*

PubMed Central

Fu, Zhisong; Jeong, Won-Ki; Pan, Yongsheng; Kirby, Robert M.; Whitaker, Ross T.

2012-01-01

This paper presents an efficient, fine-grained parallel algorithm for solving the Eikonal equation on triangular meshes. The Eikonal equation, and the broader class of Hamilton–Jacobi equations to which it belongs, have a wide range of applications from geometric optics and seismology to biological modeling and analysis of geometry and images. The ability to solve such equations accurately and efficiently provides new capabilities for exploring and visualizing parameter spaces and for solving inverse problems that rely on such equations in the forward model. Efficient solvers on state-of-the-art, parallel architectures require new algorithms that are not, in many cases, optimal, but are better suited to synchronous updates of the solution. In previous work [W. K. Jeong and R. T. Whitaker, SIAM J. Sci. Comput., 30 (2008), pp. 2512–2534], the authors proposed the fast iterative method (FIM) to efficiently solve the Eikonal equation on regular grids. In this paper we extend the fast iterative method to solve Eikonal equations efficiently on triangulated domains on the CPU and on parallel architectures, including graphics processors. We propose a new local update scheme that provides solutions of first-order accuracy for both architectures. We also propose a novel triangle-based update scheme and its corresponding data structure for efficient irregular data mapping to parallel single-instruction multiple-data (SIMD) processors. We provide detailed descriptions of the implementations on a single CPU, a multicore CPU with shared memory, and SIMD architectures with comparative results against state-of-the-art Eikonal solvers. PMID:22641200

Do Children’s Health Resources Differ According to Preschool Physical Activity Programmes and Parental Behaviour? A Mixed Methods Study

PubMed Central

Sterdt, Elena; Pape, Natalie; Kramer, Silke; Liersch, Sebastian; Urban, Michael; Werning, Rolf; Walter, Ulla

2014-01-01

Preschool can have positive effects on the development of a healthy lifestyle. The present study analysed to what extent different conditions, structures and behavioural models in preschool and family—children’s central social microsystems—can lead to differences in children’s health resources. Using a cross-sectional mixed methods approach, contrast analyses of “preschools with systematic physical activity programmes” versus “preschools without physical activity programmes” were conducted to assess the extent to which children’s physical activity, quality of life and social behaviour differ between preschools with systematic and preschools without physical activity programmes. Differences in children’s physical activity according to parental behaviour were likewise assessed. Data on child-related outcomes and parent-related factors were collected via parent questionnaires and child interviews. A qualitative focused ethnographic study was performed to obtain deeper insight into the quantitative survey data. Two hundred and twenty seven (227) children were interviewed at 21 preschools with systematic physical activity programmes, and 190 at 25 preschools without physical activity programmes. There was no significant difference in children’s physical activity levels between the two preschool types (p = 0.709). However, the qualitative data showed differences in the design and quality of programmes to promote children’s physical activity. Data triangulation revealed a strong influence of parental behaviour. The triangulation of methods provided comprehensive insight into the nature and extent of physical activity programmes in preschools and made it possible to capture the associations between systematic physical activity promotion and children’s health resources in a differential manner. PMID:24577283

Perceived benefits and barriers to joint protection among people with rheumatoid arthritis and occupational therapists. A mixed methods study.

PubMed

Niedermann, K; Hammond, A; Forster, A; de Bie, R

2010-09-01

Deciding whether or not to perform a health behaviour is an active decision-making process which has an impact on current and future behaviour and can be influenced by the beliefs both of patients and their healthcare professionals. The aim of this study was to explore rheumatoid arthritis (RA) patients' and occupational therapists' (OTs) perceptions of the benefits of and barriers to performing joint protection (JP). A mixed methods design was used. Questionnaires applied a theoretical framework of key themes to assess the relevance of JP benefits and barriers both to people with RA and OTs. Focused interviews with people with RA then enabled data triangulation. Investigator triangulation was used to check the validity of data interpretation. Ten people with RA and nine OTs participated. From the questionnaires, both groups agreed that highly relevant key themes for JP benefits were physical well-being, potential benefit and personal control. By contrast, the three key themes for JP barriers - negative attitude of others, negative impact on others and taking time from other things - were relevant for the majority of the OTs but not patients. The interviews enabled an understanding of the meaning behind RA patients' ratings, particularly their differences from OTs. People with RA explained JP benefits, and disease acceptance had altered some initial barriers into perceived benefits over time. Emphasizing benefits and identifying individually relevant barriers could be an important communication strategy for OTs in understanding patients' rationale for whether or not to adopt JP methods. Copyright 2010 John Wiley & Sons, Ltd.

Do children's health resources differ according to preschool physical activity programmes and parental behaviour? A mixed methods study.

PubMed

Sterdt, Elena; Pape, Natalie; Kramer, Silke; Liersch, Sebastian; Urban, Michael; Werning, Rolf; Walter, Ulla

2014-02-26

Preschool can have positive effects on the development of a healthy lifestyle. The present study analysed to what extent different conditions, structures and behavioural models in preschool and family-children's central social microsystems-can lead to differences in children's health resources. Using a cross-sectional mixed methods approach, contrast analyses of "preschools with systematic physical activity programmes" versus "preschools without physical activity programmes" were conducted to assess the extent to which children's physical activity, quality of life and social behaviour differ between preschools with systematic and preschools without physical activity programmes. Differences in children's physical activity according to parental behaviour were likewise assessed. Data on child-related outcomes and parent-related factors were collected via parent questionnaires and child interviews. A qualitative focused ethnographic study was performed to obtain deeper insight into the quantitative survey data. Two hundred and twenty seven (227) children were interviewed at 21 preschools with systematic physical activity programmes, and 190 at 25 preschools without physical activity programmes. There was no significant difference in children's physical activity levels between the two preschool types (p = 0.709). However, the qualitative data showed differences in the design and quality of programmes to promote children's physical activity. Data triangulation revealed a strong influence of parental behaviour. The triangulation of methods provided comprehensive insight into the nature and extent of physical activity programmes in preschools and made it possible to capture the associations between systematic physical activity promotion and children's health resources in a differential manner.

Depth Extraction from Videos Using Geometric Context and Occlusion Boundaries (Open Access)

DTIC Science & Technology

2014-09-05

RAZA ET AL .: DEPTH EXTRACTION FROM VIDEOS 1 Depth Extraction from Videos Using Geometric Context and Occlusion Boundaries S. Hussain Raza1...electronic forms. ar X iv :1 51 0. 07 31 7v 1 [ cs .C V ] 2 5 O ct 2 01 5 2 RAZA ET AL .: DEPTH EXTRACTION FROM VIDEOS Frame Ground Truth Depth...temporal segmentation using the method proposed by Grundmann et al . [4]. estimation and triangulation to estimate depth maps [17, 27](see Figure 1). In

A topological hierarchy for functions on triangulated surfaces.

PubMed

Bremer, Peer-Timo; Edelsbrunner, Herbert; Hamann, Bernd; Pascucci, Valerio

2004-01-01

We combine topological and geometric methods to construct a multiresolution representation for a function over a two-dimensional domain. In a preprocessing stage, we create the Morse-Smale complex of the function and progressively simplify its topology by cancelling pairs of critical points. Based on a simple notion of dependency among these cancellations, we construct a hierarchical data structure supporting traversal and reconstruction operations similarly to traditional geometry-based representations. We use this data structure to extract topologically valid approximations that satisfy error bounds provided at runtime.

Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

NASA Astrophysics Data System (ADS)

Décréau, Pierrette; Kougblénou, Séna; Lointier, Guillaume; Rauch, Jean Louis; Trotignon, Jean Gabriel; Vallières, Xavier; Canu, Patrick; Rochel Grimald, Sandrine; El-Lemdani Mazouz, Farida; Darrouzet, Fabien

2014-05-01

The non-thermal continuum (NTC) radiation is a radio wave produced within the magnetosphere of a planet. It has been observed in space around Earth since the '70s, and within the magnetospheres of other planets since the late '80s. A new study using ESA's Cluster mission has shown improved precision in determining the source of various radio emissions produced by the Earth. The experiment involved tilting one of the four identical Cluster spacecraft to measure the electric field of this emission in three dimensions for the first time. Our analysis of a NTC case event pinpointed a small deviation from the generally assumed (circular) polarization of this emission. We show that classical triangulation, in this case using three of the spacecraft located thousands of kilometres apart, can lead to an erroneous source location. A second method, using the new 3D electric field measurements, indicated a source located along the plasmapause at medium geomagnetic latitude, far away from the source location estimated by triangulation. Cluster observations reveal that this NTC source emits from the flank of the plasmapause towards the polar cap. Understanding the source of NTC waves will help with the broader understanding of their generation, amplification, and propagation.

Uncertainty quantification in volumetric Particle Image Velocimetry

NASA Astrophysics Data System (ADS)

Bhattacharya, Sayantan; Charonko, John; Vlachos, Pavlos

2016-11-01

Particle Image Velocimetry (PIV) uncertainty quantification is challenging due to coupled sources of elemental uncertainty and complex data reduction procedures in the measurement chain. Recent developments in this field have led to uncertainty estimation methods for planar PIV. However, no framework exists for three-dimensional volumetric PIV. In volumetric PIV the measurement uncertainty is a function of reconstructed three-dimensional particle location that in turn is very sensitive to the accuracy of the calibration mapping function. Furthermore, the iterative correction to the camera mapping function using triangulated particle locations in space (volumetric self-calibration) has its own associated uncertainty due to image noise and ghost particle reconstructions. Here we first quantify the uncertainty in the triangulated particle position which is a function of particle detection and mapping function uncertainty. The location uncertainty is then combined with the three-dimensional cross-correlation uncertainty that is estimated as an extension of the 2D PIV uncertainty framework. Finally the overall measurement uncertainty is quantified using an uncertainty propagation equation. The framework is tested with both simulated and experimental cases. For the simulated cases the variation of estimated uncertainty with the elemental volumetric PIV error sources are also evaluated. The results show reasonable prediction of standard uncertainty with good coverage.

Virtual Boutique: a 3D modeling and content-based management approach to e-commerce

NASA Astrophysics Data System (ADS)

Paquet, Eric; El-Hakim, Sabry F.

2000-12-01

The Virtual Boutique is made out of three modules: the decor, the market and the search engine. The decor is the physical space occupied by the Virtual Boutique. It can reproduce any existing boutique. For this purpose, photogrammetry is used. A set of pictures of a real boutique or space is taken and a virtual 3D representation of this space is calculated from them. Calculations are performed with software developed at NRC. This representation consists of meshes and texture maps. The camera used in the acquisition process determines the resolution of the texture maps. Decorative elements are added like painting, computer generated objects and scanned objects. The objects are scanned with laser scanner developed at NRC. This scanner allows simultaneous acquisition of range and color information based on white laser beam triangulation. The second module, the market, is made out of all the merchandises and the manipulators, which are used to manipulate and compare the objects. The third module, the search engine, can search the inventory based on an object shown by the customer in order to retrieve similar objects base don shape and color. The items of interest are displayed in the boutique by reconfiguring the market space, which mean that the boutique can be continuously customized according to the customer's needs. The Virtual Boutique is entirely written in Java 3D and can run in mono and stereo mode and has been optimized in order to allow high quality rendering.

Methods for determining optical power, for power-normalizing laser measurements, and for stabilizing power of lasers via compliance voltage sensing

DOEpatents

Taubman, Matthew S; Phillips, Mark C

2015-04-07

A method is disclosed for power normalization of spectroscopic signatures obtained from laser based chemical sensors that employs the compliance voltage across a quantum cascade laser device within an external cavity laser. The method obviates the need for a dedicated optical detector used specifically for power normalization purposes. A method is also disclosed that employs the compliance voltage developed across the laser device within an external cavity semiconductor laser to power-stabilize the laser mode of the semiconductor laser by adjusting drive current to the laser such that the output optical power from the external cavity semiconductor laser remains constant.

A Method of DTM Construction Based on Quadrangular Irregular Networks and Related Error Analysis

PubMed Central

Kang, Mengjun

2015-01-01

A new method of DTM construction based on quadrangular irregular networks (QINs) that considers all the original data points and has a topological matrix is presented. A numerical test and a real-world example are used to comparatively analyse the accuracy of QINs against classical interpolation methods and other DTM representation methods, including SPLINE, KRIGING and triangulated irregular networks (TINs). The numerical test finds that the QIN method is the second-most accurate of the four methods. In the real-world example, DTMs are constructed using QINs and the three classical interpolation methods. The results indicate that the QIN method is the most accurate method tested. The difference in accuracy rank seems to be caused by the locations of the data points sampled. Although the QIN method has drawbacks, it is an alternative method for DTM construction. PMID:25996691

Commutative semigroups of real and complex matrices. [with use of the jordan form

NASA Technical Reports Server (NTRS)

Brown, D. R.

1974-01-01

The computation of divergence is studied. Covariance matrices to be analyzed admit a common diagonalization, or even triangulation. Sufficient conditions are given for such phenomena to take place, the arguments cover both real and complex matrices, and are not restricted to Hermotian or other special forms. Specifically, it is shown to be sufficient that the matrices in question commute in order to admit a common triangulation. Several results hold in the case that the matrices in question form a closed and bounded set, rather than only in the finite case.

Spectral Analysis for Weighted Iterated Triangulations of Graphs

NASA Astrophysics Data System (ADS)

Chen, Yufei; Dai, Meifeng; Wang, Xiaoqian; Sun, Yu; Su, Weiyi

Much information about the structural properties and dynamical aspects of a network is measured by the eigenvalues of its normalized Laplacian matrix. In this paper, we aim to present a first study on the spectra of the normalized Laplacian of weighted iterated triangulations of graphs. We analytically obtain all the eigenvalues, as well as their multiplicities from two successive generations. As an example of application of these results, we then derive closed-form expressions for their multiplicative Kirchhoff index, Kemeny’s constant and number of weighted spanning trees.

Error in telemetry studies: Effects of animal movement on triangulation

USGS Publications Warehouse

Schmutz, Joel A.; White, Gary C.

1990-01-01

We used Monte Carlo simulations to investigate the effects of animal movement on error of estimated animal locations derived from radio-telemetry triangulation of sequentially obtained bearings. Simulated movements of 0-534 m resulted in up to 10-fold increases in average location error but <10% decreases in location precision when observer-to-animal distances were <1,000 m. Location error and precision were minimally affected by censorship of poor locations with Chi-square goodness-of-fit tests. Location error caused by animal movement can only be eliminated by taking simultaneous bearings.

Influence of survey strategy and interpolation model on DEM quality

NASA Astrophysics Data System (ADS)

Heritage, George L.; Milan, David J.; Large, Andrew R. G.; Fuller, Ian C.

2009-11-01

Accurate characterisation of morphology is critical to many studies in the field of geomorphology, particularly those dealing with changes over time. Digital elevation models (DEMs) are commonly used to represent morphology in three dimensions. The quality of the DEM is largely a function of the accuracy of individual survey points, field survey strategy, and the method of interpolation. Recommendations concerning field survey strategy and appropriate methods of interpolation are currently lacking. Furthermore, the majority of studies to date consider error to be uniform across a surface. This study quantifies survey strategy and interpolation error for a gravel bar on the River Nent, Blagill, Cumbria, UK. Five sampling strategies were compared: (i) cross section; (ii) bar outline only; (iii) bar and chute outline; (iv) bar and chute outline with spot heights; and (v) aerial LiDAR equivalent, derived from degraded terrestrial laser scan (TLS) data. Digital Elevation Models were then produced using five different common interpolation algorithms. Each resultant DEM was differentiated from a terrestrial laser scan of the gravel bar surface in order to define the spatial distribution of vertical and volumetric error. Overall triangulation with linear interpolation (TIN) or point kriging appeared to provide the best interpolators for the bar surface. Lowest error on average was found for the simulated aerial LiDAR survey strategy, regardless of interpolation technique. However, comparably low errors were also found for the bar-chute-spot sampling strategy when TINs or point kriging was used as the interpolator. The magnitude of the errors between survey strategy exceeded those found between interpolation technique for a specific survey strategy. Strong relationships between local surface topographic variation (as defined by the standard deviation of vertical elevations in a 0.2-m diameter moving window), and DEM errors were also found, with much greater errors found at slope breaks such as bank edges. A series of curves are presented that demonstrate these relationships for each interpolation and survey strategy. The simulated aerial LiDAR data set displayed the lowest errors across the flatter surfaces; however, sharp slope breaks are better modelled by the morphologically based survey strategy. The curves presented have general application to spatially distributed data of river beds and may be applied to standard deviation grids to predict spatial error within a surface, depending upon sampling strategy and interpolation algorithm.

User-centered requirements engineering in health information systems: a study in the hemophilia field.

PubMed

Teixeira, Leonor; Ferreira, Carlos; Santos, Beatriz Sousa

2012-06-01

The use of sophisticated information and communication technologies (ICTs) in the health care domain is a way to improve the quality of services. However, there are also hazards associated with the introduction of ICTs in this domain and a great number of projects have failed due to the lack of systematic consideration of human and other non-technology issues throughout the design or implementation process, particularly in the requirements engineering process. This paper presents the methodological approach followed in the design process of a web-based information system (WbIS) for managing the clinical information in hemophilia care, which integrates the values and practices of user-centered design (UCD) activities into the principles of software engineering, particularly in the phase of requirements engineering (RE). This process followed a paradigm that combines a grounded theory for data collection with an evolutionary design based on constant development and refinement of the generic domain model using three well-known methodological approaches: (a) object-oriented system analysis; (b) task analysis; and, (c) prototyping, in a triangulation work. This approach seems to be a good solution for the requirements engineering process in this particular case of the health care domain, since the inherent weaknesses of individual methods are reduced, and emergent requirements are easier to elicit. Moreover, the requirements triangulation matrix gives the opportunity to look across the results of all used methods and decide what requirements are critical for the system success. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Confirming, Classifying, and Prioritizing Needed Over-the-Bed Table Improvements via Methodological Triangulation.

PubMed

Manganelli, Joe; Threatt, Anthony; Brooks, Johnell O; Healy, Stan; Merino, Jessica; Yanik, Paul; Walker, Ian; Green, Keith

2014-01-01

This article presents the results of a qualitative study that confirmed, classified, and prioritized user needs for the design of a more useful, usable, and actively assistive over-the-bed table. Manganelli et al. (2014) generated a list of 74 needs for use in developing an actively assistive over-the-bed table. This present study assesses the value and importance of those needs. Fourteen healthcare subject matter experts and eight research and design subject matter experts engaged in a participatory and iterative research and design process. A mixed methods qualitative approach used methodological triangulation to confirm the value of the findings and ratings to establish importance. Open and closed card sorts and a Delphi study were used. Data analysis methods included frequency analysis, content analysis, and a modified Kano analysis. A table demonstrating the needs that are of high importance to both groups of subject matter experts and classification of the design challenges each represents was produced. Through this process, the list of 74 needs was refined to the 37 most important need statements for both groups. Designing a more useful, usable, and actively assistive over-the-bed table is primarily about the ability to position it optimally with respect to the user for any task, as well as improving ease of use and usability. It is also important to make explicit and discuss the differences in priorities and perspectives demonstrated between research and design teams and their clients. © 2014 Vendome Group, LLC.

Low cost 3D scanning process using digital image processing

NASA Astrophysics Data System (ADS)

Aguilar, David; Romero, Carlos; Martínez, Fernando

2017-02-01

This paper shows the design and building of a low cost 3D scanner, able to digitize solid objects through contactless data acquisition, using active object reflection. 3D scanners are used in different applications such as: science, engineering, entertainment, etc; these are classified in: contact scanners and contactless ones, where the last ones are often the most used but they are expensive. This low-cost prototype is done through a vertical scanning of the object using a fixed camera and a mobile horizontal laser light, which is deformed depending on the 3-dimensional surface of the solid. Using digital image processing an analysis of the deformation detected by the camera was done; it allows determining the 3D coordinates using triangulation. The obtained information is processed by a Matlab script, which gives to the user a point cloud corresponding to each horizontal scanning done. The obtained results show an acceptable quality and significant details of digitalized objects, making this prototype (built on LEGO Mindstorms NXT kit) a versatile and cheap tool, which can be used for many applications, mainly by engineering students.

Initial alignment method for free space optics laser beam

NASA Astrophysics Data System (ADS)

Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

2016-08-01

The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

Optimized stereo matching in binocular three-dimensional measurement system using structured light.

PubMed

Liu, Kun; Zhou, Changhe; Wei, Shengbin; Wang, Shaoqing; Fan, Xin; Ma, Jianyong

2014-09-10

In this paper, we develop an optimized stereo-matching method used in an active binocular three-dimensional measurement system. A traditional dense stereo-matching algorithm is time consuming due to a long search range and the high complexity of a similarity evaluation. We project a binary fringe pattern in combination with a series of N binary band limited patterns. In order to prune the search range, we execute an initial matching before exhaustive matching and evaluate a similarity measure using logical comparison instead of a complicated floating-point operation. Finally, an accurate point cloud can be obtained by triangulation methods and subpixel interpolation. The experiment results verify the computational efficiency and matching accuracy of the method.

Clinical application of laser treatment for cardiovascular surgery

PubMed Central

Okada, Masayoshi; Yoshida, Masato; Tsuji, Yoshihiko; Horii, Hiroyuki

2011-01-01

Background: Recently, several kinds of lasers have been widely employed in the field of medicine and surgery. However, laser applications are very rare in the field of cardiovascular surgery throughout the world. So, we have experimentally tried to use lasers in the field of cardiovascular surgery. There were three categories: 1) Transmyocardial laser revascularization (TMLR), 2) Laser vascular anastomosis, and 3) Laser angioplasty in the peripheral arterial diseases. By the way, surgery for ischemic heart disease has been widely performed in Japan. Especially coronary artery bypass grafting (CABG) for these patients has been done as a popular surgical method. Among these patients there are a few cases for whom CABG and percutaneous coronary intervention (PCI) could not be carried out, because of diffuse stenosis and small caliber of coronary arteries. Materials and methods of TMLR: A new method of tranasmyocardial revascularization by CO2 laser (output 100 W, irradiation time 0.2 sec) was experimentally performed to save severely ill patients. In this study, a feasibility of transmyocardial laser revascularization from left ventricular cavity through artificially created channels by laser was precisely evaluated. Results: In trials on dogs laser holes 0.2mm in diameter have been shown microscopically to be patent even 3 years after their creation, thus this procedure could be used as a new method of transmyocardial laser revascularization. Clinical application of TMLR: Subsequently, transmyocardial laser revascularization was employed in a 55-year-old male patient with severe angina pectoris who had undergone pericardiectomy 7 years before. He was completely recovered from severe chest pain. Conclusions of TMLR: This patient was the first successful case in the world with TMLR alone. This method might be done for the patients who percutaneous coronary intervention and coronary artery bypass grafting could be carried out. Laser vascular anastomosis: At present time, in vascular surgery there are some problems to keep long-term patency after anastomosis of the conventional suture method, especially for small-caliber vessels. Materials and methods of Laser vascular anastomosis: From these standpoints, a low energy CO2 laser was employed experimentally in vascular anastomosis for small-caliber vessels. Resullts of Laser vascular anastomosis: From preliminary experiments it could be concluded that the optimal laser output was 20–40 mW and irradiation time was 6–12 sec/mm for vascular anastomosis of small-caliber vessels in the extremities. And then, histologic findings and intensity of the laser anastomotic sites were investigated thereafter. Subseqently, good enough intensity and good healing of laser anastomotic sites as well as the conventional suture method could be observed. There were no statistic differences between laser and suture methods. A feasibility of laser anastomosis could be considered and clinical application could be recognized. Clinical applications of Laser vascular anastomosis: On February 21, 1985, arterio-venous laser anastomosis for the patient with renal failure was smoothly done and she could accept hemodialysis. Conclusions of Laser vascular anastomosis: This patient was the first clinical successful case in the world. Thereafter, Laser vascular anastomosis were in 111 patients with intermittent claudication, refractory crural ulcer, and coronary disorders. Thereafter, they are going well. Laser angioplasty: Laser angioplasty for peripheral arterial diseases. There are many methods to treat peripheral arterial diseases such as balloon method, atherectomy, laser technique and stenting graft in the field of endovascular treatment. Recent years, minimal invasive treatment should be employed even in the surgical treatment. However, there are different images between these methods. Materials and methods of Laser angioplasty: We have chosen to use laser for endovascular treatment for peripheral arterial diseases. We have tried to check between laser energy and vessel wall. Results of Laser angioplasty: Subsequently, it could be concluded that optimal conditions for laser angioplasty were 6 W in output and irradiation time was 5 sec. And with another method of feedback control system, temperature of metal tip probe was 200°C and irradiation time was 5 sec for each shot. And histological study and feasibility of angioscopic guidance could be done and clinical application was started. Until now, 115 patients were successfully treated with their life longevity. Conclusions of Laser angioplasty: Thus, laser applications were useful methods to treat a lot of patients with some ischemic problems. PMID:24155531

A line fiducial method for geometric calibration of cone-beam CT systems with diverse scan trajectories

NASA Astrophysics Data System (ADS)

Jacobson, M. W.; Ketcha, M. D.; Capostagno, S.; Martin, A.; Uneri, A.; Goerres, J.; De Silva, T.; Reaungamornrat, S.; Han, R.; Manbachi, A.; Stayman, J. W.; Vogt, S.; Kleinszig, G.; Siewerdsen, J. H.

2018-01-01

Modern cone-beam CT systems, especially C-arms, are capable of diverse source-detector orbits. However, geometric calibration of these systems using conventional configurations of spherical fiducials (BBs) may be challenged for novel source-detector orbits and system geometries. In part, this is because the BB configurations are designed with careful forethought regarding the intended orbit so that BB marker projections do not overlap in projection views. Examples include helical arrangements of BBs (Rougee et al 1993 Proc. SPIE 1897 161-9) such that markers do not overlap in projections acquired from a circular orbit and circular arrangements of BBs (Cho et al 2005 Med. Phys. 32 968-83). As a more general alternative, this work proposes a calibration method based on an array of line-shaped, radio-opaque wire segments. With this method, geometric parameter estimation is accomplished by relating the 3D line equations representing the wires to the 2D line equations of their projections. The use of line fiducials simplifies many challenges with fiducial recognition and extraction in an orbit-independent manner. For example, their projections can overlap only mildly, for any gantry pose, as long as the wires are mutually non-coplanar in 3D. The method was tested in application to circular and non-circular trajectories in simulation and in real orbits executed using a mobile C-arm prototype for cone-beam CT. Results indicated high calibration accuracy, as measured by forward and backprojection/triangulation error metrics. Triangulation errors on the order of microns and backprojected ray deviations uniformly less than 0.2 mm were observed in both real and simulated orbits. Mean forward projection errors less than 0.1 mm were observed in a comprehensive sweep of different C-arm gantry angulations. Finally, successful integration of the method into a CT imaging chain was demonstrated in head phantom scans.

Sampling theory and automated simulations for vertical sections, applied to human brain.

PubMed

Cruz-Orive, L M; Gelšvartas, J; Roberts, N

2014-02-01

In recent years, there have been substantial developments in both magnetic resonance imaging techniques and automatic image analysis software. The purpose of this paper is to develop stereological image sampling theory (i.e. unbiased sampling rules) that can be used by image analysts for estimating geometric quantities such as surface area and volume, and to illustrate its implementation. The methods will ideally be applied automatically on segmented, properly sampled 2D images - although convenient manual application is always an option - and they are of wide applicability in many disciplines. In particular, the vertical sections design to estimate surface area is described in detail and applied to estimate the area of the pial surface and of the boundary between cortex and underlying white matter (i.e. subcortical surface area). For completeness, cortical volume and mean cortical thickness are also estimated. The aforementioned surfaces were triangulated in 3D with the aid of FreeSurfer software, which provided accurate surface area measures that served as gold standards. Furthermore, a software was developed to produce digitized trace curves of the triangulated target surfaces automatically from virtual sections. From such traces, a new method (called the 'lambda method') is presented to estimate surface area automatically. In addition, with the new software, intersections could be counted automatically between the relevant surface traces and a cycloid test grid for the classical design. This capability, together with the aforementioned gold standard, enabled us to thoroughly check the performance and the variability of the different estimators by Monte Carlo simulations for studying the human brain. In particular, new methods are offered to split the total error variance into the orientations, sectioning and cycloid components. The latter prediction was hitherto unavailable--one is proposed here and checked by way of simulations on a given set of digitized vertical sections with automatically superimposed cycloid grids of three different sizes. Concrete and detailed recommendations are given to implement the methods. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

SU-C-18A-02: Image-Based Camera Tracking: Towards Registration of Endoscopic Video to CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ingram, S; Rao, A; Wendt, R

Purpose: Endoscopic examinations are routinely performed on head and neck and esophageal cancer patients. However, these images are underutilized for radiation therapy because there is currently no way to register them to a CT of the patient. The purpose of this work is to develop a method to track the motion of an endoscope within a structure using images from standard clinical equipment. This method will be incorporated into a broader endoscopy/CT registration framework. Methods: We developed a software algorithm to track the motion of an endoscope within an arbitrary structure. We computed frame-to-frame rotation and translation of the cameramore » by tracking surface points across the video sequence and utilizing two-camera epipolar geometry. The resulting 3D camera path was used to recover the surrounding structure via triangulation methods. We tested this algorithm on a rigid cylindrical phantom with a pattern spray-painted on the inside. We did not constrain the motion of the endoscope while recording, and we did not constrain our measurements using the known structure of the phantom. Results: Our software algorithm can successfully track the general motion of the endoscope as it moves through the phantom. However, our preliminary data do not show a high degree of accuracy in the triangulation of 3D point locations. More rigorous data will be presented at the annual meeting. Conclusion: Image-based camera tracking is a promising method for endoscopy/CT image registration, and it requires only standard clinical equipment. It is one of two major components needed to achieve endoscopy/CT registration, the second of which is tying the camera path to absolute patient geometry. In addition to this second component, future work will focus on validating our camera tracking algorithm in the presence of clinical imaging features such as patient motion, erratic camera motion, and dynamic scene illumination.« less

Superlative TINs

NASA Technical Reports Server (NTRS)

Chamberlin, R.

2002-01-01

TIN is short for 'triangulated irregular network,' which is a piecewise planar model of a surface. If properly constructed, a TIN can be more than 30 times as efficient as a regular triangulation. In our project (a ground combat simulation to support U.S. Army training exercises), the TIN is used to represent the Earth's surface and is used primarily to determine whether line of sight is blocked by terrain. High efficiency requires accurate identification of ridgelines with as few triangles as possible. The work currently in progress is the implementation of a TINning process that we hope will produce superlative TINs. This presentation describes that process.

First Instances of Generalized Expo-Rational Finite Elements on Triangulations

NASA Astrophysics Data System (ADS)

Dechevsky, Lubomir T.; Zanaty, Peter; Laksa˚, Arne; Bang, Børre

2011-12-01

In this communication we consider a construction of simplicial finite elements on triangulated two-dimensional polygonal domains. This construction is, in some sense, dual to the construction of generalized expo-rational B-splines (GERBS). The main result is in the obtaining of new polynomial simplicial patches of the first several lowest possible total polynomial degrees which exhibit Hermite interpolatory properties. The derivation of these results is based on the theory of piecewise polynomial GERBS called Euler Beta-function B-splines. We also provide 3-dimensional visualization of the graphs of the new polynomial simplicial patches and their control polygons.

Positive geometries and canonical forms

NASA Astrophysics Data System (ADS)

Arkani-Hamed, Nima; Bai, Yuntao; Lam, Thomas

2017-11-01

Recent years have seen a surprising connection between the physics of scattering amplitudes and a class of mathematical objects — the positive Grassmannian, positive loop Grassmannians, tree and loop Amplituhedra — which have been loosely referred to as "positive geometries". The connection between the geometry and physics is provided by a unique differential form canonically determined by the property of having logarithmic singularities (only) on all the boundaries of the space, with residues on each boundary given by the canonical form on that boundary. The structures seen in the physical setting of the Amplituhedron are both rigid and rich enough to motivate an investigation of the notions of "positive geometries" and their associated "canonical forms" as objects of study in their own right, in a more general mathematical setting. In this paper we take the first steps in this direction. We begin by giving a precise definition of positive geometries and canonical forms, and introduce two general methods for finding forms for more complicated positive geometries from simpler ones — via "triangulation" on the one hand, and "push-forward" maps between geometries on the other. We present numerous examples of positive geometries in projective spaces, Grassmannians, and toric, cluster and flag varieties, both for the simplest "simplex-like" geometries and the richer "polytope-like" ones. We also illustrate a number of strategies for computing canonical forms for large classes of positive geometries, ranging from a direct determination exploiting knowledge of zeros and poles, to the use of the general triangulation and push-forward methods, to the representation of the form as volume integrals over dual geometries and contour integrals over auxiliary spaces. These methods yield interesting representations for the canonical forms of wide classes of positive geometries, ranging from the simplest Amplituhedra to new expressions for the volume of arbitrary convex polytopes.

After critical care: patient support after critical care. A mixed method longitudinal study using email interviews and questionnaires.

PubMed

Pattison, Natalie; O'Gara, Geraldine; Rattray, Janice

2015-08-01

To explore experiences and needs over time, of patients discharged from ICU using the Intensive Care Experience (ICE-q) questionnaire, Hospital Anxiety and Depression Scale (HADS) and EuroQoL (EQ-5D), associated clinical predictors (APACHE II, TISS, Length of stay, RIKER scores) and in-depth email interviewing. A mixed-method, longitudinal study of patients with >48hour ICU stays at 2 weeks, 6 months, 12 months using the ICE-q, HADS, EQ-5D triangulated with clinical predictors, including age, gender, length of stay (ICU and hospital), APACHE II and TISS. In-depth qualitative email interviews were completed at 1 month and 6 months. Grounded Theory analysis was applied to interview data and data were triangulated with questionnaire and clinical data. Data was collected from January 2010 to March 2012 from 77 participants. Both mean EQ-5D visual analogue scale, utility scores and HADS scores improved from 2 weeks to 6 months, (p=<0.001; p=<0.001), but between 6 and 12 months, no change was found in data from either questionnaire, suggesting improvements level off. These variations were reflected in qualitative data themes: rehabilitation/recovery in the context of chronic illness; impact of critical care; emotional and psychological needs (including sub-themes of: information needs and relocation anxiety). The overarching, core theme related to adjustment of normality. Patient recovery in this population appears to be shaped by ongoing illness and treatment. Email interviews offer a convenient method of gaining in-depth interview data and could be used as part of ICU follow-up. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Markerless positional verification using template matching and triangulation of kV images acquired during irradiation for lung tumors treated in breath-hold

NASA Astrophysics Data System (ADS)

Hazelaar, Colien; Dahele, Max; Mostafavi, Hassan; van der Weide, Lineke; Slotman, Ben; Verbakel, Wilko

2018-06-01

Lung tumors treated in breath-hold are subject to inter- and intra-breath-hold variations, which makes tumor position monitoring during each breath-hold important. A markerless technique is desirable, but limited tumor visibility on kV images makes this challenging. We evaluated if template matching  +  triangulation of kV projection images acquired during breath-hold stereotactic treatments could determine 3D tumor position. Band-pass filtering and/or digital tomosynthesis (DTS) were used as image pre-filtering/enhancement techniques. On-board kV images continuously acquired during volumetric modulated arc irradiation of (i) a 3D-printed anthropomorphic thorax phantom with three lung tumors (n  =  6 stationary datasets, n  =  2 gradually moving), and (ii) four patients (13 datasets) were analyzed. 2D reference templates (filtered DRRs) were created from planning CT data. Normalized cross-correlation was used for 2D matching between templates and pre-filtered/enhanced kV images. For 3D verification, each registration was triangulated with multiple previous registrations. Generally applicable image processing/algorithm settings for lung tumors in breath-hold were identified. For the stationary phantom, the interquartile range of the 3D position vector was on average 0.25 mm for 12° DTS  +  band-pass filtering (average detected positions in 2D  =  99.7%, 3D  =  96.1%, and 3D excluding first 12° due to triangulation angle  =  99.9%) compared to 0.81 mm for band-pass filtering only (55.8/52.9/55.0%). For the moving phantom, RMS errors for the lateral/longitudinal/vertical direction after 12° DTS  +  band-pass filtering were 1.5/0.4/1.1 mm and 2.2/0.3/3.2 mm. For the clinical data, 2D position was determined for at least 93% of each dataset and 3D position excluding first 12° for at least 82% of each dataset using 12° DTS  +  band-pass filtering. Template matching  +  triangulation using DTS  +  band-pass filtered images could accurately determine the position of stationary lung tumors. However, triangulation was less accurate/reliable for targets with continuous, gradual displacement in the lateral and vertical directions. This technique is therefore currently most suited to detect/monitor offsets occurring between initial setup and the start of treatment, inter-breath-hold variations, and tumors with predominantly longitudinal motion.

Laser processing for manufacturing nanocarbon materials

NASA Astrophysics Data System (ADS)

Van, Hai Hoang

CNTs have been considered as the excellent candidate to revolutionize a broad range of applications. There have been many method developed to manipulate the chemistry and the structure of CNTs. Laser with non-contact treatment capability exhibits many processing advantages, including solid-state treatment, extremely fast processing rate, and high processing resolution. In addition, the outstanding monochromatic, coherent, and directional beam generates the powerful energy absorption and the resultant extreme processing conditions. In my research, a unique laser scanning method was developed to process CNTs, controlling the oxidation and the graphitization. The achieved controllability of this method was applied to address the important issues of the current CNT processing methods for three applications. The controllable oxidation of CNTs by laser scanning method was applied to cut CNT films to produce high-performance cathodes for FE devices. The production method includes two important self-developed techniques to produce the cold cathodes: the production of highly oriented and uniformly distributed CNT sheets and the precise laser trimming process. Laser cutting is the unique method to produce the cathodes with remarkable features, including ultrathin freestanding structure (~200 nm), greatly high aspect ratio, hybrid CNT-GNR emitter arrays, even emitter separation, and directional emitter alignment. This unique cathode structure was unachievable by other methods. The developed FE devices successfully solved the screening effect issue encounter by current FE devices. The laser-control oxidation method was further developed to sequentially remove graphitic walls of CNTs. The laser oxidation process was directed to occur along the CNT axes by the laser scanning direction. Additionally, the oxidation was further assisted by the curvature stress and the thermal expansion of the graphitic nanotubes, ultimately opening (namely unzipping) the tubular structure to produce GNRs. Therefore the developed laser scanning method optimally exploited the thermal laser-CNT interaction, successfully transforming CNTs into 2D GNRs. The solid-state laser unzipping process effectively addressed the issues of contamination and scalability encountered by the current unzipping methods. Additionally, the produced GNRs were uniquely featured with the freestanding structure and the smooth surfaces. If the scanning process was performed in an inert environment without the appearance of oxygen, the oxidation of CNTs would not happen. Instead, the greatly mobile carbon atoms of the heated CNTs would reorganize the crystal structure, inducing the graphitization process to improve the crystallinity. Many observations showing the structural improvement of CNTs under laser irradiation has been reported, confirming the capability of laser to heal graphitic defects. Laser methods were more time-efficient and energy-efficient than other annealing methods because laser can quickly heat CNTs to generate graphitization in less than one second. This subsecond heating process of laser irradiation was more effective than other heating methods because it avoided the undesired coalescence of CNTs. In my research, the laser scanning method was applied to generate the graphitization, healing the structural defects of CNTs. Different from the reported laser methods, the laser scanning directed the locally annealed areas to move along the CNT axes, migrating and coalescencing the graphitic defects to achieve better healing results. The critical information describing the CNT structural transformation caused by the moving laser irradiation was explored from the successful applications of the developed laser method. This knowledge inspires an important method to modifiy the general graphitic structure for important applications, such as carbon fiber production, CNT self-assembly process and CNT welding. This method will be effective, facile, versatile, and adaptable for laboratory and industrial facilities.

B-spline Method in Fluid Dynamics

NASA Technical Reports Server (NTRS)

Botella, Olivier; Shariff, Karim; Mansour, Nagi N. (Technical Monitor)

2001-01-01

B-spline functions are bases for piecewise polynomials that possess attractive properties for complex flow simulations : they have compact support, provide a straightforward handling of boundary conditions and grid nonuniformities, and yield numerical schemes with high resolving power, where the order of accuracy is a mere input parameter. This paper reviews the progress made on the development and application of B-spline numerical methods to computational fluid dynamics problems. Basic B-spline approximation properties is investigated, and their relationship with conventional numerical methods is reviewed. Some fundamental developments towards efficient complex geometry spline methods are covered, such as local interpolation methods, fast solution algorithms on cartesian grid, non-conformal block-structured discretization, formulation of spline bases of higher continuity over triangulation, and treatment of pressure oscillations in Navier-Stokes equations. Application of some of these techniques to the computation of viscous incompressible flows is presented.

Fast Voronoi Diagrams and Offsets on Triangulated Surfaces

DTIC Science & Technology

2000-01-01

118 (1996), 499-508. 14. Malladi , R ., and J. A. Sethian, An O(N log N) algorithm for shape mod- eling, Proceedings of National Academy of Sciences...rights of reproduction in any form reserved. 194 R . Kimmel and J. A. Sethian the Osher-Sethian level set method [16,20], which grew out of Sethian’s...where .F(x, y) : R 2 -* R + is a function that defines a weight for each point in the domain. The distance map T(x, y) from a given point Po assigns

An Effective 3D Ear Acquisition System

PubMed Central

Liu, Yahui; Lu, Guangming; Zhang, David

2015-01-01

The human ear is a new feature in biometrics that has several merits over the more common face, fingerprint and iris biometrics. It can be easily captured from a distance without a fully cooperative subject. Also, the ear has a relatively stable structure that does not change much with the age and facial expressions. In this paper, we present a novel method of 3D ear acquisition system by using triangulation imaging principle, and the experiment results show that this design is efficient and can be used for ear recognition. PMID:26061553

National geodetic satellite program, part 2

NASA Technical Reports Server (NTRS)

Schmid, H.

1977-01-01

Satellite geodesy and the creation of worldwide geodetic reference systems is discussed. The geometric description of the surface and the analytical description of the gravity field of the earth by means of worldwide reference systems, with the aid of satellite geodesy, are presented. A triangulation method based on photogrammetric principles is described in detail. Results are derived in the form of three dimensional models. These mathematical models represent the frame of reference into which one can fit the existing geodetic results from the various local datums, as well as future measurements.

An adaptation strategy of sandland peasants in Yogyakarta toward climate change

NASA Astrophysics Data System (ADS)

Rusdiyana, E.; Suminah

2018-03-01

This study aims to explore and describe the adaptation strategies of sandland peasants toward climate change. Qualitative research method was employed and the data were collected through observation. In addition, the recording of the data, interview and the validity of data were determined by triangulation of sources. The results of the research showed that the adaptation strategies of sandland peasants toward climate change were; (1) the adjustment of crop varieties, (2) the utilization of productive crops as wind breaking, and (3) the irrigation system using “sumur panthek”.

An Effective 3D Ear Acquisition System.

PubMed

Liu, Yahui; Lu, Guangming; Zhang, David

2015-01-01

The human ear is a new feature in biometrics that has several merits over the more common face, fingerprint and iris biometrics. It can be easily captured from a distance without a fully cooperative subject. Also, the ear has a relatively stable structure that does not change much with the age and facial expressions. In this paper, we present a novel method of 3D ear acquisition system by using triangulation imaging principle, and the experiment results show that this design is efficient and can be used for ear recognition.

Enhanced Optical Head Tracking for Cranial Radiation Therapy: Supporting Surface Registration by Cutaneous Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wissel, Tobias, E-mail: wissel@rob.uni-luebeck.de; Graduate School for Computing in Medicine and Life Science, University of Lübeck, Lübeck; Stüber, Patrick

2016-06-01

Purpose: To support surface registration in cranial radiation therapy by structural information. The risk for spatial ambiguities is minimized by using tissue thickness variations predicted from backscattered near-infrared (NIR) light from the forehead. Methods and Materials: In a pilot study we recorded NIR surface scans by laser triangulation from 30 volunteers of different skin type. A ground truth for the soft-tissue thickness was segmented from MR scans. After initially matching the NIR scans to the MR reference, Gaussian processes were trained to predict tissue thicknesses from NIR backscatter. Moreover, motion starting from this initial registration was simulated by 5000 randommore » transformations of the NIR scan away from the MR reference. Re-registration to the MR scan was compared with and without tissue thickness support. Results: By adding prior knowledge to the backscatter features, such as incident angle and neighborhood information in the scanning grid, we showed that tissue thickness can be predicted with mean errors of <0.2 mm, irrespective of the skin type. With this additional information, the average registration error improved from 3.4 mm to 0.48 mm by a factor of 7. Misalignments of more than 1 mm were almost thoroughly (98.9%) pushed below 1 mm. Conclusions: For almost all cases tissue-enhanced matching achieved better results than purely spatial registration. Ambiguities can be minimized if the cutaneous structures do not agree. This valuable support for surface registration increases tracking robustness and avoids misalignment of tumor targets far from the registration site.« less

An optoacoustic guide with augmented reality system towards precision breast conserving surgery (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lan, Lu; Liu, Kaiming; Xia, Yan; Wu, Jiayingzi; Li, Rui; Wang, Pu; Han, Linda K.; Cheng, Ji-Xin

2017-02-01

Breast-conserving surgery is a well-accepted breast cancer treatment. However, it is still challenging for the surgeon to accurately localize the tumor during the surgery. Also, the guidance provided by current methods is 1 dimensional distance information, which is indirect and not intuitive. Therefore, it creates problems on a large re-excision rate, and a prolonged surgical time. To solve these problems, we have developed a fiber-delivered optoacoustic guide (OG), which mimics the traditional localization guide wire and is preoperatively placed into tumor mass, and an augmented reality (AR) system to provide real-time visualization on the location of the tumor with sub-millimeter variance. By a nano-composite light diffusion sphere and light absorbing layer formed on the tip of an optical fiber, the OG creates an omnidirectional acoustic source inside tumor mass under pulsed laser excitation. The optoacoustic signal generated has a high dynamic range ( 58dB) and spreads in a large apex angle of 320 degrees. Then, an acoustic radar with three ultrasound transducers is attached to the breast skin, and triangulates the location of the OG tip. With an AR system to sense the location of the acoustic radar, the relative position of the OG tip inside the tumor to the AR display is calculated and rendered. This provides direct visual feedback of the tumor location to surgeons, which will greatly ease the surgical planning during the operation and save surgical time. A proof-of-concept experiment using a tablet and a stereo-vision camera is demonstrated and 0.25 mm tracking variance is achieved.

A Real-Time Monitoring System of Industry Carbon Monoxide Based on Wireless Sensor Networks.

PubMed

Yang, Jiachen; Zhou, Jianxiong; Lv, Zhihan; Wei, Wei; Song, Houbing

2015-11-20

Carbon monoxide (CO) burns or explodes at over-standard concentration. Hence, in this paper, a Wifi-based, real-time monitoring of a CO system is proposed for application in the construction industry, in which a sensor measuring node is designed by low-frequency modulation method to acquire CO concentration reliably, and a digital filtering method is adopted for noise filtering. According to the triangulation, the Wifi network is constructed to transmit information and determine the position of nodes. The measured data are displayed on a computer or smart phone by a graphical interface. The experiment shows that the monitoring system obtains excellent accuracy and stability in long-term continuous monitoring.

Psychological skills training of an elite wheelchair water-skiing athlete: a single-case study.

PubMed

de Bressy de Guast, Virginie; Golby, Jim; Van Wersch, Anna; d'Arripe-Longueville, Fabienne

2013-10-01

This study presents a complete psychological skills training (PST) program with a wheelchair athlete and examines the program effectiveness using a mixed-method approach. After initial testing, the athlete followed a two-month program of self-confidence building, motivational, visualization/relaxation, and injury management techniques. Quantitative and qualitative methods were used to examine the impacts on performance and psychological abilities. The triangulated results suggest that the PST program was perceived as effective by the athlete in terms of his sporting performances and mental skills. The characteristics and implications of a PST program with this wheelchair athlete are discussed, as well as the study limitations and the perspectives for future research.

Method and apparatus for determining the coordinates of an object

DOEpatents

Pedersen, Paul S; Sebring, Robert

2003-01-01

A method and apparatus is described for determining the coordinates on the surface of an object which is illuminated by a beam having pixels which have been modulated according to predetermined mathematical relationships with pixel position within the modulator. The reflected illumination is registered by an image sensor at a known location which registers the intensity of the pixels as received. Computations on the intensity, which relate the pixel intensities received to the pixel intensities transmitted at the modulator, yield the proportional loss of intensity and planar position of the originating pixels. The proportional loss and position information can then be utilized within triangulation equations to resolve the coordinates of associated surface locations on the object.

The relations between inadequate parent-child boundaries and borderline personality disorder in adolescence.

PubMed

Vanwoerden, Salome; Kalpakci, Allison; Sharp, Carla

2017-11-01

Borderline Personality Disorder (BPD) is a severe mental illness that onsets in adolescence. Research has demonstrated the central role of parent-child relationships for the development and maintenance of BPD although more research is necessary to clarify the specific dynamics that relate to BPD during adolescence. Based on preliminary research establishing the importance of parent-child boundaries for adolescent BPD, this study sought to evaluate the relations between different forms of inadequate boundaries and BPD in adolescence using a multi-method approach. To that end, 301 adolescents (65.1% female; ages 12-17) inpatients were recruited; parents and adolescents completed questionnaire- and interview-based measures of BPD features in adolescent children and a questionnaire-based measure of parent-child boundaries. Relations were found between parental guilt induction and psychological control with children's BPD features above and beyond relations with psychiatric severity and gender. Relations between parent reports of triangulation (when children are recruited to mediate parental marital conflict) and children's BPD were contingent on the level of children's perceptions of triangulation. Findings confirm previous research suggesting the relevance of inadequate parent-child boundaries to children's BPD features and have important implications for understanding the dynamics in families with adolescents with BPD, representing a relevant treatment target. Copyright © 2017 Elsevier B.V. All rights reserved.

In vivo miniature robots for natural orifice surgery: State of the art and future perspectives.

PubMed

Tiwari, Manish M; Reynoso, Jason F; Lehman, Amy C; Tsang, Albert W; Farritor, Shane M; Oleynikov, Dmitry

2010-06-27

Natural orifice translumenal endoscopic surgery (NOTES) is the integration of laparoscopic minimally invasive surgery techniques with endoscopic technology. Despite the advances in NOTES technology, the approach presents several unique instrumentation and technique-specific challenges. Current flexible endoscopy platforms for NOTES have several drawbacks including limited stability, triangulation and dexterity, and lack of adequate visualization, suggesting the need for new and improved instrumentation for this approach. Much of the current focus is on the development of flexible endoscopy platforms that incorporate robotic technology. An alternative approach to access the abdominal viscera for either a laparoscopic or NOTES procedure is the use of small robotic devices that can be implanted in an intracorporeal manner. Multiple, independent, miniature robots can be simultaneously inserted into the abdominal cavity to provide a robotic platform for NOTES surgery. The capabilities of the robots include imaging, retraction, tissue and organ manipulation, and precise maneuverability in the abdominal cavity. Such a platform affords several advantages including enhanced visualization, better surgical dexterity and improved triangulation for NOTES. This review discusses the current status and future perspectives of this novel miniature robotics platform for the NOTES approach. Although these technologies are still in pre-clinical development, a miniature robotics platform provides a unique method for addressing the limitations of minimally invasive surgery, and NOTES in particular.

Handheld pose tracking using vision-inertial sensors with occlusion handling

NASA Astrophysics Data System (ADS)

Li, Juan; Slembrouck, Maarten; Deboeverie, Francis; Bernardos, Ana M.; Besada, Juan A.; Veelaert, Peter; Aghajan, Hamid; Casar, José R.; Philips, Wilfried

2016-07-01

Tracking of a handheld device's three-dimensional (3-D) position and orientation is fundamental to various application domains, including augmented reality (AR), virtual reality, and interaction in smart spaces. Existing systems still offer limited performance in terms of accuracy, robustness, computational cost, and ease of deployment. We present a low-cost, accurate, and robust system for handheld pose tracking using fused vision and inertial data. The integration of measurements from embedded accelerometers reduces the number of unknown parameters in the six-degree-of-freedom pose calculation. The proposed system requires two light-emitting diode (LED) markers to be attached to the device, which are tracked by external cameras through a robust algorithm against illumination changes. Three data fusion methods have been proposed, including the triangulation-based stereo-vision system, constraint-based stereo-vision system with occlusion handling, and triangulation-based multivision system. Real-time demonstrations of the proposed system applied to AR and 3-D gaming are also included. The accuracy assessment of the proposed system is carried out by comparing with the data generated by the state-of-the-art commercial motion tracking system OptiTrack. Experimental results show that the proposed system has achieved high accuracy of few centimeters in position estimation and few degrees in orientation estimation.

Application Possibility of Smartphone as Payload for Photogrammetric Uav System

NASA Astrophysics Data System (ADS)

Yun, M. H.; Kim, J.; Seo, D.; Lee, J.; Choi, C.

2012-07-01

Smartphone can not only be operated under 3G network environment anytime and anyplace but also cost less than the existing photogrammetric UAV since it provides high-resolution image, 3D location and attitude data on a real-time basis from a variety of built-in sensors. This study is aimed to assess the possibility of smartphone as a payload for photogrammetric UAV system. Prior to such assessment, a smartphone-based photogrammetric UAV system application was developed, through which real-time image, location and attitude data was obtained using smartphone under both static and dynamic conditions. Subsequently the accuracy assessment on the location and attitude data obtained and sent by this system was conducted. The smartphone images were converted into ortho-images through image triangulation. The image triangulation was conducted in accordance with presence or absence of consideration of the interior orientation (IO) parameters determined by camera calibration. In case IO parameters were taken into account in the static experiment, the results from triangulation for any smartphone type were within 1.5 pixel (RMSE), which was improved at least by 35% compared to when IO parameters were not taken into account. On the contrary, the improvement effect of considering IO parameters on accuracy in triangulation for smartphone images in dynamic experiment was not significant compared to the static experiment. It was due to the significant impact of vibration and sudden attitude change of UAV on the actuator for automatic focus control within the camera built in smartphone under the dynamic condition. This cause appears to have a negative impact on the image-based DEM generation. Considering these study findings, it is suggested that smartphone is very feasible as a payload for UAV system. It is also expected that smartphone may be loaded onto existing UAV playing direct or indirect roles significantly.

The modern trends of the evolution laser information technology in oncology

NASA Astrophysics Data System (ADS)

Mikov, A. A.; Svirin, V. N.

2008-04-01

Laser-optical information technologies and devices develop since the 70- years at the end of 20 century and are broadly used for diagnostics and treatment of oncological diseases to date. Although such methods as photodynamic therapy (PDT), laser-induce thermotherapy (LITT), fluorescent diagnostics and spectrophotometry already more than 30 years are used for treatment and diagnostics of oncological diseases, nevertheless, they are enough new methods and, as a rule, are used in large scientific centers and medical institutions. This is bound, first of all, with lack of information on modern method of cancer treatment, the absence of widely available laser procedures and corresponding devices in the polyclinics and even in district hospitals, as well as insufficient understanding of application areas, where laser methods has an advantage by comparison, for instance, with beam or chemotherapy. At present day laser methods are fast upcoming direction of the treatment oncological diseases. This is explained by progress in development essentially laser, particularly diode, improvement electronic and computing components and broad introduction software-algorithmic methods of control the undertaking therapeutic and diagnostic procedures. In article are considered new laser methods of the undertaking diagnostic and therapeutic procedures and is shown that introduction multiwave laser radiation for probe and influences on tissue, the different methods of the determination of the functional state of tissues, realization of the on-line diagnostics when carrying out the therapeutic procedures, automatic control systems of the power laser radiation, which depends on state patient tissue, as well as software-algorithmic methods of management session therapeutic and diagnostic procedures greatly raises efficiency of the treatment oncological diseases. On an example of the multipurpose laser therapeutic devices("MLTA") developed and introduced in clinical practice and multipurpose laser diagnostic complexes ("MLDC"), the realizing offered methods, are shown the basic tendencies of development laser methods in oncology, concrete technical decisions and the experimental clinical material showing increase of efficiency of treatment of a cancer at their realization are resulted. It is shown, that realization of the offered methods and technical technologies opens new competitive advantages laser technologies in comparison with beam and chemical-therapy at treatment of oncological diseases.

Optical tomography by means of regularized MLEM

NASA Astrophysics Data System (ADS)

Majer, Charles L.; Urbanek, Tina; Peter, Jörg

2015-09-01

To solve the inverse problem involved in fluorescence mediated tomography a regularized maximum likelihood expectation maximization (MLEM) reconstruction strategy is proposed. This technique has recently been applied to reconstruct galaxy clusters in astronomy and is adopted here. The MLEM algorithm is implemented as Richardson-Lucy (RL) scheme and includes entropic regularization and a floating default prior. Hence, the strategy is very robust against measurement noise and also avoids converging into noise patterns. Normalized Gaussian filtering with fixed standard deviation is applied for the floating default kernel. The reconstruction strategy is investigated using the XFM-2 homogeneous mouse phantom (Caliper LifeSciences Inc., Hopkinton, MA) with known optical properties. Prior to optical imaging, X-ray CT tomographic data of the phantom were acquire to provide structural context. Phantom inclusions were fit with various fluorochrome inclusions (Cy5.5) for which optical data at 60 projections over 360 degree have been acquired, respectively. Fluorochrome excitation has been accomplished by scanning laser point illumination in transmission mode (laser opposite to camera). Following data acquisition, a 3D triangulated mesh is derived from the reconstructed CT data which is then matched with the various optical projection images through 2D linear interpolation, correlation and Fourier transformation in order to assess translational and rotational deviations between the optical and CT imaging systems. Preliminary results indicate that the proposed regularized MLEM algorithm, when driven with a constant initial condition, yields reconstructed images that tend to be smoother in comparison to classical MLEM without regularization. Once the floating default prior is included this bias was significantly reduced.

A Modified Magnetic Gradient Contraction Based Method for Ferromagnetic Target Localization

PubMed Central

Wang, Chen; Zhang, Xiaojuan; Qu, Xiaodong; Pan, Xiao; Fang, Guangyou; Chen, Luzhao

2016-01-01

The Scalar Triangulation and Ranging (STAR) method, which is based upon the unique properties of magnetic gradient contraction, is a high real-time ferromagnetic target localization method. Only one measurement point is required in the STAR method and it is not sensitive to changes in sensing platform orientation. However, the localization accuracy of the method is limited by the asphericity errors and the inaccurate value of position leads to larger errors in the estimation of magnetic moment. To improve the localization accuracy, a modified STAR method is proposed. In the proposed method, the asphericity errors of the traditional STAR method are compensated with an iterative algorithm. The proposed method has a fast convergence rate which meets the requirement of high real-time localization. Simulations and field experiments have been done to evaluate the performance of the proposed method. The results indicate that target parameters estimated by the modified STAR method are more accurate than the traditional STAR method. PMID:27999322

Spectroscopic and laser characterization of emerald. Final report, April 1983-April 1986

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, S.T.; Chai, B.H.

1986-08-01

The spectroscopic characteristics and laser properties of emerald were investigated. The laser measurements showed that the emerald-laser tuning range was 720-842 nm and exhibited a high gain and high efficiency in the 760-790 nm range. Under a crystal growth development program, the laser loss was reduced from 11%/cm to 0.4%/cm. The limiting factor in the laser efficiency is the excited-state absorption (ESA). The ESA was measured by two methods: a laser-pumped single-pass gain method, which is generally applicable to all tunable laser materials, and a laser-pumped laser method. A 76% laser quantum yield was obtained in high-optical-quality emerald. The maximummore » yield is estimated to be 83%, based on the ESA measurements.« less

Simplification of the laser absorption process in the particle simulation for the laser-induced shockwave processing

NASA Astrophysics Data System (ADS)

Shimamura, Kohei

2016-09-01

To reduce the computational cost in the particle method for the numerical simulation of the laser plasma, we examined the simplification of the laser absorption process. Because the laser frequency is sufficiently larger than the collision frequency between the electron and heavy particles, we assumed that the electron obtained the constant value from the laser irradiation. First of all, the simplification of the laser absorption process was verified by the comparison of the EEDF and the laser-absorptivity with PIC-FDTD method. Secondary, the laser plasma induced by TEA CO2 laser in Argon atmosphere was modeled using the 1D3V DSMC method with the simplification of the laser-absorption. As a result, the LSDW was observed with the typical electron and neutral density distribution.

A new method and device of aligning patient setup lasers in radiation therapy.

PubMed

Hwang, Ui-Jung; Jo, Kwanghyun; Lim, Young Kyung; Kwak, Jung Won; Choi, Sang Hyuon; Jeong, Chiyoung; Kim, Mi Young; Jeong, Jong Hwi; Shin, Dongho; Lee, Se Byeong; Park, Jeong-Hoon; Park, Sung Yong; Kim, Siyong

2016-01-08

The aim of this study is to develop a new method to align the patient setup lasers in a radiation therapy treatment room and examine its validity and efficiency. The new laser alignment method is realized by a device composed of both a metallic base plate and a few acrylic transparent plates. Except one, every plate has either a crosshair line (CHL) or a single vertical line that is used for alignment. Two holders for radiochromic film insertion are prepared in the device to find a radiation isocenter. The right laser positions can be found optically by matching the shadows of all the CHLs in the gantry head and the device. The reproducibility, accuracy, and efficiency of laser alignment and the dependency on the position error of the light source were evaluated by comparing the means and the standard deviations of the measured laser positions. After the optical alignment of the lasers, the radiation isocenter was found by the gantry and collimator star shots, and then the lasers were translated parallel to the isocenter. In the laser position reproducibility test, the mean and standard deviation on the wall of treatment room were 32.3 ± 0.93 mm for the new method whereas they were 33.4 ± 1.49 mm for the conventional method. The mean alignment accuracy was 1.4 mm for the new method, and 2.1 mm for the conventional method on the walls. In the test of the dependency on the light source position error, the mean laser position was shifted just by a similar amount of the shift of the light source in the new method, but it was greatly magnified in the conventional method. In this study, a new laser alignment method was devised and evaluated successfully. The new method provided more accurate, more reproducible, and faster alignment of the lasers than the conventional method.

Using mixed methods to assess fidelity of delivery and its influencing factors in a complex self-management intervention for people with osteoarthritis and low back pain

PubMed Central

Toomey, Elaine; Matthews, James; Hurley, Deirdre A

2017-01-01

Objectives and design Despite an increasing awareness of the importance of fidelity of delivery within complex behaviour change interventions, it is often poorly assessed. This mixed methods study aimed to establish the fidelity of delivery of a complex self-management intervention and explore the reasons for these findings using a convergent/triangulation design. Setting Feasibility trial of the Self-management of Osteoarthritis and Low back pain through Activity and Skills (SOLAS) intervention (ISRCTN49875385), delivered in primary care physiotherapy. Methods and outcomes 60 SOLAS sessions were delivered across seven sites by nine physiotherapists. Fidelity of delivery of prespecified intervention components was evaluated using (1) audio-recordings (n=60), direct observations (n=24) and self-report checklists (n=60) and (2) individual interviews with physiotherapists (n=9). Quantitatively, fidelity scores were calculated using percentage means and SD of components delivered. Associations between fidelity scores and physiotherapist variables were analysed using Spearman’s correlations. Interviews were analysed using thematic analysis to explore potential reasons for fidelity scores. Integration of quantitative and qualitative data occurred at an interpretation level using triangulation. Results Quantitatively, fidelity scores were high for all assessment methods; with self-report (92.7%) consistently higher than direct observations (82.7%) or audio-recordings (81.7%). There was significant variation between physiotherapists’ individual scores (69.8% - 100%). Both qualitative and quantitative data (from physiotherapist variables) found that physiotherapists’ knowledge (Spearman’s association at p=0.003) and previous experience (p=0.008) were factors that influenced their fidelity. The qualitative data also postulated participant-level (eg, individual needs) and programme-level factors (eg, resources) as additional elements that influenced fidelity. Conclusion The intervention was delivered with high fidelity. This study contributes to the limited evidence regarding fidelity assessment methods within complex behaviour change interventions. The findings suggest a combination of quantitative methods is suitable for the assessment of fidelity of delivery. A mixed methods approach provided a more insightful understanding of fidelity and its influencing factors. Trial registration number ISRCTN49875385; Pre-results. PMID:28780544

Critically appraising qualitative research: a guide for clinicians more familiar with quantitative techniques.

PubMed

Kisely, Stephen; Kendall, Elizabeth

2011-08-01

Papers using qualitative methods are increasingly common in psychiatric journals. This overview is an introduction to critically appraising a qualitative paper for clinicians who are more familiar with quantitative methods. Qualitative research uses data from interviews (semi-structured or unstructured), focus groups, observations or written materials. Data analysis is inductive, allowing meaning to emerge from the data, rather than the more deductive, hypothesis centred approach of quantitative research. This overview compares and contrasts quantitative and qualitative research methods. Quantitative concepts such as reliability, validity, statistical power, bias and generalisability have qualitative equivalents. These include triangulation, trustworthiness, saturation, reflexivity and applicability. Reflexivity also shares features of transference. Qualitative approaches include: ethnography, action-assessment, grounded theory, case studies and mixed methods. Qualitative research can complement quantitative approaches. An understanding of both is useful in critically appraising the psychiatric literature.

Marginal elasticity of periodic triangulated origami

NASA Astrophysics Data System (ADS)

Chen, Bryan; Sussman, Dan; Lubensky, Tom; Santangelo, Chris

Origami, the classical art of folding paper, has inspired much recent work on assembling complex 3D structures from planar sheets. Origami, and more generally hinged structures with rigid panels, where all faces are triangles have special properties due to having a bulk balance of mechanical degrees of freedom and constraints. We study two families of periodic triangulated origami structures, one based on the Miura ori and one based on a kagome-like pattern due to Ron Resch. We point out the consequences of the balance of degrees of freedom and constraints for these ''metamaterial plates'' and show how the elasticity can be tuned by changing the unit cell geometry.

Asymmetric peer selections among Blacks, Asians, and Whites in a virtual environment: Preliminary evidence for triangulated threat theory.

PubMed

Tawa, John

2017-01-01

Black, Asian, and White participants (N = 210) created self-resembling avatars and engaged in peer-selection tasks during social events in the virtual world, Second Life, that were designed to simulate various types of resource competition. Participants in merit-based resource competition settings had less diversity in their peer groups compared to participants in settings where no resource competition was present, and Asian participants had lower preference for Black peers. Furthermore, these relationships were mediated by out-group discomfort. Results are discussed in relation to partial support for triangulated threat theory of group relations among Blacks, Asians, and Whites.

Analysis of the relationship between lung cancer drug response level and atom connectivity dynamics based on trimmed Delaunay triangulation

NASA Astrophysics Data System (ADS)

Zou, Bin; Wang, Debby D.; Ma, Lichun; Chen, Lijiang; Yan, Hong

2016-05-01

Epidermal growth factor receptor (EGFR) mutation is a pathogenic factor of non-small cell lung cancer (NSCLC). Tyrosine kinase inhibitors (TKIs), such as gefitinib, are widely used in NSCLC treatment. In this work, we investigated the relationship between the number of EGFR residues connected with gefitinib and the response level for each EGFR mutation type. Three-dimensional trimmed Delaunay triangulation was applied to construct connections between EGFR residues and gefitinib atoms. Through molecular dynamics (MD) simulations, we discovered that when the number of EGFR residues connected with gefitinib increases, the response level of the corresponding EGFR mutation tends to descend.

Satellite triangulation in Europe from WEST and ISAGEX data. [computer programs

NASA Technical Reports Server (NTRS)

Leick, A.; Arur, M.

1975-01-01

Observational data that was acquired during the West European Satellite Triangulation (WEST) program and the International Satellite Geodesy Experiment (ISAGEX) campaign was obtained for the purpose of performing a geometric solution to improve the present values of coordinates of the European stations in the OSU WN14 solutions, adding some new stations and assessing the quality of the WN14 solution with the help of the additional data available. The status of the data as received, the preprocessing required and the preliminary tests carried out for the initial screening of the data are described. The adjustment computations carried out and the results of the adjustments are discussed.

One Century of Tectonic Deformation Along the Sumatran Fault from Triangulation and GPS Surveys

NASA Technical Reports Server (NTRS)

Prawirodirdjo, L.; Bock, Y.; Genrich, J. F.; Puntodewo, S. S. O.; Rais, J.; Subarya, C.; Sutisna, S.

2000-01-01

An analysis combining historical triangulation and recent Global Positioning System (GPS) survey measurements in West and North Sumatra, Indonesia, reveals a detailed slip history along the central part of the Sumatran Fault. The arc-parallel components of the combined velocity field are consistent with slip rates inferred from GPS data, ranging from 23 to 24 mm/yr. Between 1.0 S and 1.3 N the Sumatran Fault appears to be characterized by deep locking depths, on the order of 20 km, and the occurrence of large (M (sub w) approximately 7) earthquakes. The long-term (1883-1993) strains show simple right-lateral shear, with rates similar to GPS-measured, 1989-1993 strain rates. Coseismic deformation due to the 1892 Tapanuli and 1926 Padang Panjang earthquakes, estimated from triangulation measurements taken before and after the events, indicate that the main shocks were significantly larger than previously reported. The 1892 earthquake had a likely magnitude of M (sub w) approximately equal to 7.6, while the 1926 events appear to be comparable in size to the subsequent (M approximately 7) 1943 events, and an order of magnitude higher than previously reported.

Complex network view of evolving manifolds

NASA Astrophysics Data System (ADS)

da Silva, Diamantino C.; Bianconi, Ginestra; da Costa, Rui A.; Dorogovtsev, Sergey N.; Mendes, José F. F.

2018-03-01

We study complex networks formed by triangulations and higher-dimensional simplicial complexes representing closed evolving manifolds. In particular, for triangulations, the set of possible transformations of these networks is restricted by the condition that at each step, all the faces must be triangles. Stochastic application of these operations leads to random networks with different architectures. We perform extensive numerical simulations and explore the geometries of growing and equilibrium complex networks generated by these transformations and their local structural properties. This characterization includes the Hausdorff and spectral dimensions of the resulting networks, their degree distributions, and various structural correlations. Our results reveal a rich zoo of architectures and geometries of these networks, some of which appear to be small worlds while others are finite dimensional with Hausdorff dimension equal or higher than the original dimensionality of their simplices. The range of spectral dimensions of the evolving triangulations turns out to be from about 1.4 to infinity. Our models include simplicial complexes representing manifolds with evolving topologies, for example, an h -holed torus with a progressively growing number of holes. This evolving graph demonstrates features of a small-world network and has a particularly heavy-tailed degree distribution.

Opioid use and harms associated with a sustained-release tapentadol formulation: a postmarketing study protocol

PubMed Central

Larance, Briony; Farrell, Michael; Cairns, Rose; Buckley, Nicholas; Degenhardt, Louisa

2018-01-01

Introduction It has been argued that tapentadol may pharmacologically have lower abuse potential than other pharmaceutical opioids currently available. However, there has been no comprehensive triangulation of data regarding use and harms associated with this formulation. A sustained-release formulation (SRF) of tapentadol (Palexia) was released in Australia in 2011 and listed for public subsidy in 2013. We summarise here the methods of a postmarketing study which will measure postintroduction: (1) population level availability, (2) extramedical use and diversion, (3) attractiveness for extramedical use and (4) associated harms, of tapentadol compared against other pharmaceutical opioids. Methods and analysis We evaluated key sources on pharmaceutical use and harms in Australia. This review indicateddata from four sources that disaggregate pharmaceutical opioid formulations and capture tapentadol SRF could be triangulated. These data sources comprised: (1) national pharmaceutical opioid community sales data from 2011 to 2017, (2) national pharmaceutical opioid poisonings reported to Poison Information Centres (PICs) from 2011 to 2017, (3) number of vendors on online marketplaces listing pharmaceutical opioids for sale and (4) data on pharmaceutical opioid extramedical use, attractiveness and harms from interviews with people who regularly inject drugs in Australia. Ethics and dissemination Ethics approval is not required for use of pharmaceutical sales data. Ethics approval has been obtained for use of national pharmaceutical opioid poisonings reported to PICs (LNR/16/SCHN/44) and for use of online marketplace data and interview data from people who inject drugs (HC12086). Key findings will be published mid-2018 in a peer-reviewed academic journal, and presented at various conferences and professional meetings. PMID:29574444

Diode Laser Ear Piercing: A Novel Technique.

PubMed

Suseela, Bibilash Babu; Babu, Preethitha; Chittoria, Ravi Kumar; Mohapatra, Devi Prasad

2016-01-01

Earlobe piercing is a common office room procedure done by a plastic surgeon. Various methods of ear piercing have been described. In this article, we describe a novel method of laser ear piercing using the diode laser. An 18-year-old female patient underwent an ear piercing using a diode laser with a power of 2.0 W in continuous mode after topical local anaesthetic and pre-cooling. The diode laser was fast, safe, easy to use and highly effective way of ear piercing. The advantages we noticed while using the diode laser over conventional methods were more precision, minimal trauma with less chances of hypertrophy and keloids, no bleeding with coagulation effect of laser, less time taken compared to conventional method and less chance of infection due to thermal heat effect of laser.

Laser pulse shape design for laser-indirect-driven quasi-isentropic compression experiments

NASA Astrophysics Data System (ADS)

Xue, Quanxi; Jiang, Shaoen; Wang, Zhebin; Wang, Feng; Zhao, Xueqing; Ding, Yongkun

2018-02-01

Laser pulse shape design is a key work in the design of indirect-laser-driven experiments, especially for long pulse laser driven quasi-isentropic compression experiments. A method for designing such a laser pulse shape is given here. What's more, application experiments were performed, and the results of a typical shot are presented. At last of this article, the details of the application of the method are discussed, such as the equation parameter choice, radiation ablation pressure expression, and approximations in the method. The application shows that the method can provide reliable descriptions of the energy distribution in a hohlraum target; thus, it can be used in the design of long-pulse laser driven quasi-isentropic compression experiments and even other indirect-laser-driven experiments.

Back analysis of Swiss flood danger map to define local flood hazards

NASA Astrophysics Data System (ADS)

Choffet, Marc; Derron, Marc-Henri; Jaboyedoff, Michel; Leroi, Eric; Mayis, Arnaud

2010-05-01

The flood hazard maps for the entire Switzerland will be available at the end of 2011. Furthermore, the Swiss territory has been covered by aerial laser scanning (ALS) providing high resolution digital elevation model (DEM). This paper describes the development of a method for analyzing the local flood hazard based on Swiss hazard maps and HR-DEM. In their original state, Swiss hazard maps are constructed on the basis of an aggregation of information, a matrix intensity, and frequency. The degree of danger represented by the yellow, blue and red zones gives no information on the water level at each point of the territory. The developed method is based on a superposition of the danger map with the HR-DEM to determine the water level in a hazard area. To perform this method, (1) a triangulation is based on the intersection of the hazard map with the HR-DEM. It uses the limits of area where information is contrain. The hazard map perimeter and the boundaries of hazard areas give information on the widest possible overflow in case of flooding. It is also possible to associate it with a return period. (2) Based on these areas and the difference with the DEM, it is possible to calibrate the highest flood level and the extract water levels for the entire area. This analysis of existing documents opens up interesting perspectives for understanding how infrastructures are threatened by flood hazard by predicting water levels and potential damages to buildings while proposing remedial measures. Indeed, this method allows estimating the water level at each point of a building in case of flooding. It is designed to provide spatial information on water height levels; this offers a different approach of buildings in danger zones. Indeed, it is possible to discern several elements, such as areas of water accumulation involving longer flood duration, possible structural damages to buildings due to high hydrostatic pressure, determination of a local hazard, or the display of water levels in 3D.

The Amateur Scientist.

ERIC Educational Resources Information Center

Walker, Jearl

1981-01-01

Describes several methods by which an amateur might prepare a laser light display in the home or the classroom. Methods described include the use of particles in lasers, filters, reflecting laser beams, vibration's effects on laser beams, rotating mirrors, and the use of prisms with laser beams. (DS)

Repetitive output laser system and method using target reflectivity

DOEpatents

Johnson, Roy R.

1978-01-01

An improved laser system and method for implosion of a thermonuclear fuel pellet in which that portion of a laser pulse reflected by the target pellet is utilized in the laser system to initiate a succeeding target implosion, and in which the energy stored in the laser system to amplify the initial laser pulse, but not completely absorbed thereby, is used to amplify succeeding laser pulses initiated by target reflection.

An overview of the laser ranging method of space laser altimeter

NASA Astrophysics Data System (ADS)

Zhou, Hui; Chen, Yuwei; Hyyppä, Juha; Li, Song

2017-11-01

Space laser altimeter is an active remote sensing instrument to measure topographic map of Earth, Moon and planetary. The space laser altimeter determines the range between the instrument and laser footprint by measuring round trip time of laser pulse. The return pulse reflected from ground surface is gathered by the receiver of space laser altimeter, the pulsewidth and amplitude of which are changeable with the variability of the ground relief. Meantime, several kinds of noise overlapped on the return pulse signal affect its signal-to-noise ratio. To eliminate the influence of these factors that cause range walk and range uncertainty, the reliable laser ranging methods need to be implemented to obtain high-precision range results. Based on typical space laser altimeters in the past few decades, various ranging methods are expounded in detail according to the operational principle of instruments and timing method. By illustrating the concrete procedure of determining time of flight of laser pulse, this overview provides the comparison of the employed technologies in previous and undergoing research programs and prospect innovative technology for space laser altimeters in future.

Theoretical model for frequency locking a diode laser with a Faraday cell

NASA Technical Reports Server (NTRS)

Wanninger, P.; Shay, T. M.

1992-01-01

A new method was developed for frequency locking a diode lasers, called 'the Faraday anomalous dispersion optical transmitter (FADOT) laser locking', which is much simpler than other known locking schemes. The FADOT laser locking method uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. The FADOT method is vibration insensitive and exhibits minimal thermal expansion effects. The system has a frequency pull in the range of 443.2 GHz (9 A). The method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters.

A rapid and non-invasive method for measuring the peak positive pressure of HIFU fields by a laser beam.

PubMed

Wang, Hua; Zeng, Deping; Chen, Ziguang; Yang, Zengtao

2017-04-12

Based on the acousto-optic interaction, we propose a laser deflection method for rapidly, non-invasively and quantitatively measuring the peak positive pressure of HIFU fields. In the characterization of HIFU fields, the effect of nonlinear propagation is considered. The relation between the laser deflection length and the peak positive pressure is derived. Then the laser deflection method is assessed by comparing it with the hydrophone method. The experimental results show that the peak positive pressure measured by laser deflection method is little higher than that obtained by the hydrophone, confirming that they are in reasonable agreement. Considering that the peak pressure measured by hydrophones is always underestimated, the laser deflection method is assumed to be more accurate than the hydrophone method due to the absence of the errors in hydrophone spatial-averaging measurement and the influence of waveform distortion on hydrophone corrections. Moreover, noting that the Lorentz formula still remains applicable to high-pressure environments, the laser deflection method exhibits a great potential for measuring HIFU field under high-pressure amplitude. Additionally, the laser deflection method provides a rapid way for measuring the peak positive pressure, without the scan time, which is required by the hydrophones.

Using mixed methods to assess fidelity of delivery and its influencing factors in a complex self-management intervention for people with osteoarthritis and low back pain.

PubMed

Toomey, Elaine; Matthews, James; Hurley, Deirdre A

2017-08-04

Despite an increasing awareness of the importance of fidelity of delivery within complex behaviour change interventions, it is often poorly assessed. This mixed methods study aimed to establish the fidelity of delivery of a complex self-management intervention and explore the reasons for these findings using a convergent/triangulation design. Feasibility trial of the Self-management of Osteoarthritis and Low back pain through Activity and Skills (SOLAS) intervention (ISRCTN49875385), delivered in primary care physiotherapy. 60 SOLAS sessions were delivered across seven sites by nine physiotherapists. Fidelity of delivery of prespecified intervention components was evaluated using (1) audio-recordings (n=60), direct observations (n=24) and self-report checklists (n=60) and (2) individual interviews with physiotherapists (n=9). Quantitatively, fidelity scores were calculated using percentage means and SD of components delivered. Associations between fidelity scores and physiotherapist variables were analysed using Spearman's correlations. Interviews were analysed using thematic analysis to explore potential reasons for fidelity scores. Integration of quantitative and qualitative data occurred at an interpretation level using triangulation. Quantitatively, fidelity scores were high for all assessment methods; with self-report (92.7%) consistently higher than direct observations (82.7%) or audio-recordings (81.7%). There was significant variation between physiotherapists' individual scores (69.8% - 100%). Both qualitative and quantitative data (from physiotherapist variables) found that physiotherapists' knowledge (Spearman's association at p=0.003) and previous experience (p=0.008) were factors that influenced their fidelity. The qualitative data also postulated participant-level (eg, individual needs) and programme-level factors (eg, resources) as additional elements that influenced fidelity. The intervention was delivered with high fidelity. This study contributes to the limited evidence regarding fidelity assessment methods within complex behaviour change interventions. The findings suggest a combination of quantitative methods is suitable for the assessment of fidelity of delivery. A mixed methods approach provided a more insightful understanding of fidelity and its influencing factors. ISRCTN49875385; Pre-results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

A new method and device of aligning patient setup lasers in radiation therapy

PubMed Central

Hwang, Ui‐Jung; Jo, Kwanghyun; Kwak, Jung Won; Choi, Sang Hyoun; Jeong, Chiyoung; Kim, Mi Young; Jeong, Jong Hwi; Shin, Dongho; Lee, Se Byeong; Park, Jeong‐Hoon; Park, Sung Yong; Kim, Siyong

2016-01-01

The aim of this study is to develop a new method to align the patient setup lasers in a radiation therapy treatment room and examine its validity and efficiency. The new laser alignment method is realized by a device composed of both a metallic base plate and a few acrylic transparent plates. Except one, every plate has either a crosshair line (CHL) or a single vertical line that is used for alignment. Two holders for radiochromic film insertion are prepared in the device to find a radiation isocenter. The right laser positions can be found optically by matching the shadows of all the CHLs in the gantry head and the device. The reproducibility, accuracy, and efficiency of laser alignment and the dependency on the position error of the light source were evaluated by comparing the means and the standard deviations of the measured laser positions. After the optical alignment of the lasers, the radiation isocenter was found by the gantry and collimator star shots, and then the lasers were translated parallel to the isocenter. In the laser position reproducibility test, the mean and standard deviation on the wall of treatment room were 32.3±0.93 mm for the new method whereas they were 33.4±1.49 mm for the conventional method. The mean alignment accuracy was 1.4 mm for the new method, and 2.1 mm for the conventional method on the walls. In the test of the dependency on the light source position error, the mean laser position was shifted just by a similar amount of the shift of the light source in the new method, but it was greatly magnified in the conventional method. In this study, a new laser alignment method was devised and evaluated successfully. The new method provided more accurate, more reproducible, and faster alignment of the lasers than the conventional method. PACS numbers: 87.56.Fc, 87.53.Bn, 87.53.Kn, 87.53.Ly, 87.55.Gh PMID:26894331

High power laser-mechanical drilling bit and methods of use

DOEpatents

Grubb, Daryl L.; Kolachalam, Sharath K.; Faircloth, Brian O.; Rinzler, Charles C.; Allen, Erik C.; Underwood, Lance D.; Zediker, Mark S.

2017-02-07

An apparatus with a high power laser-mechanical bit for use with a laser drilling system and a method for advancing a borehole. The laser-mechanical bit has a beam path and mechanical removal devices that provide for the removal of laser-affected rock to advance a borehole.

X-ray laser system, x-ray laser and method

DOEpatents

London, Richard A.; Rosen, Mordecai D.; Strauss, Moshe

1992-01-01

Disclosed is an x-ray laser system comprising a laser containing generating means for emitting short wave length radiation, and means external to said laser for energizing said generating means, wherein when the laser is in an operative mode emitting radiation, the radiation has a transverse coherence length to width ratio of from about 0.05 to 1. Also disclosed is a method of adjusting the parameters of the laser to achieve the desired coherence length to laser width ratio.

Laser beam alignment apparatus and method

DOEpatents

Gruhn, C.R.; Hammond, R.B.

The disclosure related to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

Laser beam alignment apparatus and method

DOEpatents

Gruhn, Charles R.; Hammond, Robert B.

1981-01-01

The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

Setup for functional cell ablation with lasers: coupling of a laser to a microscope.

PubMed

Sweeney, Sean T; Hidalgo, Alicia; de Belle, J Steven; Keshishian, Haig

2012-06-01

The selective removal of cells by ablation is a powerful tool in the study of eukaryotic developmental biology, providing much information about their origin, fate, or function in the developing organism. In Drosophila, three main methods have been used to ablate cells: chemical, genetic, and laser ablation. Each method has its own applicability with regard to developmental stage and the cells to be ablated, and its own limitations. The primary advantage of laser-based ablation is the flexibility provided by the method: The operations can be performed in any cell pattern and at any time in development. Laser-based techniques permit manipulation of structures within cells, even to the molecular level. They can also be used for gene activation. However, laser ablation can be expensive, labor-intensive, and time-consuming. Although live cells can be difficult to image in Drosophila embryos, the use of vital fluorescent imaging methods has made laser-mediated cell manipulation methods more appealing; the methods are relatively straightforward. This article provides the information necessary for setting up and using a laser microscope for lasesr ablation studies.

Optodynamic Phenomena During Laser-Activated Irrigation Within Root Canals

NASA Astrophysics Data System (ADS)

Lukač, Nejc; Gregorčič, Peter; Jezeršek, Matija

2016-07-01

Laser-activated irrigation is a powerful endodontic treatment for smear layer, bacteria, and debris removal from the root canal. In this study, we use shadow photography and the laser-beam-transmission probe to examine the dynamics of laser-induced vapor bubbles inside a root canal model and compare ultrasonic needle irrigation to the laser method. Results confirm important phenomenological differences in the two endodontic methods with the laser method resulting in much deeper irrigation. Observations of simulated debris particles show liquid vorticity effects which in our opinion represents the major cleaning mechanism.

High-speed high-efficiency 500-W cw CO2 laser hermetization of metal frames of microelectronics devices

NASA Astrophysics Data System (ADS)

Levin, Andrey V.

1996-04-01

High-speed, efficient method of laser surface treatment has been developed using (500 W) cw CO2 laser. The principal advantages of CO2 laser surface treatment in comparison with solid state lasers are the basis of the method. It has been affirmed that high efficiency of welding was a consequence of the fundamental properties of metal-IR-radiation (10,6 mkm) interaction. CO2 laser hermetization of metal frames of microelectronic devices is described as an example of the proposed method application.

Application of a laser scanner to three dimensional visual sensing tasks

NASA Technical Reports Server (NTRS)

Ryan, Arthur M.

1992-01-01

The issues are described which are associated with using a laser scanner for visual sensing and the methods developed by the author to address them. A laser scanner is a device that controls the direction of a laser beam by deflecting it through a pair of orthogonal mirrors, the orientations of which are specified by a computer. If a calibrated laser scanner is combined with a calibrated camera, it is possible to perform three dimensional sensing by directing the laser at objects within the field of view of the camera. There are several issues associated with using a laser scanner for three dimensional visual sensing that must be addressed in order to use the laser scanner effectively. First, methods are needed to calibrate the laser scanner and estimate three dimensional points. Second, methods to estimate three dimensional points using a calibrated camera and laser scanner are required. Third, methods are required for locating the laser spot in a cluttered image. Fourth, mathematical models that predict the laser scanner's performance and provide structure for three dimensional data points are necessary. Several methods were developed to address each of these and has evaluated them to determine how and when they should be applied. The theoretical development, implementation, and results when used in a dual arm eighteen degree of freedom robotic system for space assembly is described.

Detection of cystic structures using pulsed ultrasonically induced resonant cavitation

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph (Inventor); Kovach, John S. (Inventor)

2002-01-01

Apparatus and method for early detection of cystic structures indicative of ovarian and breast cancers uses ultrasonic wave energy at a unique resonance frequency for inducing cavitation in cystic fluid characteristic of cystic structures in the ovaries associated with ovarian cancer, and in cystic structures in the breast associated with breast cancer. Induced cavitation bubbles in the cystic fluid implode, creating implosion waves which are detected by ultrasonic receiving transducers attached to the abdomen of the patient. Triangulation of the ultrasonic receiving transducers enables the received signals to be processed and analyzed to identify the location and structure of the cyst.

Flattening maps for the visualization of multibranched vessels.

PubMed

Zhu, Lei; Haker, Steven; Tannenbaum, Allen

2005-02-01

In this paper, we present two novel algorithms which produce flattened visualizations of branched physiological surfaces, such as vessels. The first approach is a conformal mapping algorithm based on the minimization of two Dirichlet functionals. From a triangulated representation of vessel surfaces, we show how the algorithm can be implemented using a finite element technique. The second method is an algorithm which adjusts the conformal mapping to produce a flattened representation of the original surface while preserving areas. This approach employs the theory of optimal mass transport. Furthermore, a new way of extracting center lines for vessel fly-throughs is provided.

Flattening Maps for the Visualization of Multibranched Vessels

PubMed Central

Zhu, Lei; Haker, Steven; Tannenbaum, Allen

2013-01-01

In this paper, we present two novel algorithms which produce flattened visualizations of branched physiological surfaces, such as vessels. The first approach is a conformal mapping algorithm based on the minimization of two Dirichlet functionals. From a triangulated representation of vessel surfaces, we show how the algorithm can be implemented using a finite element technique. The second method is an algorithm which adjusts the conformal mapping to produce a flattened representation of the original surface while preserving areas. This approach employs the theory of optimal mass transport. Furthermore, a new way of extracting center lines for vessel fly-throughs is provided. PMID:15707245

Identification of nursing management diagnoses.

PubMed

Morrison, R S

1997-02-01

Theories from nursing and management provide frameworks for enhancing effectiveness of nursing management practice. The concept nursing management diagnosis has been developed by integrating nursing diagnosis and organizational diagnosis as a basis for nurse manager decision-making. Method triangulation was used to identify problems of managing nursing units, to validate those problems for relevancy to practice, to generate nursing management diagnoses, and to validate the diagnoses. Diagnoses were validated according to a definition of nursing management diagnosis provided. Of the 72 nursing management diagnoses identified, 66 were validated at a 70% level of agreement by nurse managers participating in the study.

Ground settlement monitoring based on temporarily coherent points between two SAR acquisitions

USGS Publications Warehouse

Zhang, L.; Ding, X.; Lu, Z.

2011-01-01

An InSAR analysis approach for identifying and extracting the temporarily coherent points (TCP) that exist between two SAR acquisitions and for determining motions of the TCP is presented for applications such as ground settlement monitoring. TCP are identified based on the spatial characteristics of the range and azimuth offsets of coherent radar scatterers. A method for coregistering TCP based on the offsets of TCP is given to reduce the coregistration errors at TCP. An improved phase unwrapping method based on the minimum cost flow (MCF) algorithm and local Delaunay triangulation is also proposed for sparse TCP data. The proposed algorithms are validated using a test site in Hong Kong. The test results show that the algorithms work satisfactorily for various ground features.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Feasibility of investigation of optical breakdown statistics using multifrequency lasers

NASA Astrophysics Data System (ADS)

Ulanov, S. F.

1990-06-01

A method proposed for investigating the statistics of bulk optical breakdown relies on multifrequency lasers, which eliminates the influence of the laser radiation intensity statistics. The method is based on preliminary recording of the peak intensity statistics of multifrequency laser radiation pulses at the caustic using the optical breakdown threshold of K8 glass. The probability density distribution function was obtained at the focus for the peak intensities of the radiation pulses of a multifrequency laser. This method may be used to study the self-interaction under conditions of bulk optical breakdown of transparent dielectrics.

Laser interference effect evaluation method based on character of laser-spot and image feature

NASA Astrophysics Data System (ADS)

Tang, Jianfeng; Luo, Xiaolin; Wu, Lingxia

2016-10-01

Evaluating the laser interference effect to CCD objectively and accurately has great research value. Starting from the change of the image's feature before and after interference, meanwhile, considering the influence of the laser-spot distribution character on the masking degree of the image feature information, a laser interference effect evaluation method based on character of laser-spot and image feature was proposed. It reflected the laser-spot distribution character using the distance between the center of the laser-spot and center of the target. It reflected the change of the global image feature using the changes of image's sparse coefficient matrix, which was obtained by the SSIM-inspired orthogonal matching pursuit (OMP) sparse coding algorithm. What's more, the assessment method reflected the change of the local image feature using the changes of the image's edge sharpness, which could be obtained by the change of the image's gradient magnitude. Taken together, the laser interference effect can be evaluated accurately. In terms of the laser interference experiment results, the proposed method shows good rationality and feasibility under the disturbing condition of different laser powers, and it can also overcome the inaccuracy caused by the change of the laser-spot position, realizing the evaluation of the laser interference effect objectively and accurately.

Laser-based methods for the analysis of low molecular weight compounds in biological matrices.

PubMed

Kiss, András; Hopfgartner, Gérard

2016-07-15

Laser-based desorption and/or ionization methods play an important role in the field of the analysis of low molecular-weight compounds (LMWCs) because they allow direct analysis with high-throughput capabilities. In the recent years there were several new improvements in ionization methods with the emergence of novel atmospheric ion sources such as laser ablation electrospray ionization or laser diode thermal desorption and atmospheric pressure chemical ionization and in sample preparation methods with the development of new matrix compounds for matrix-assisted laser desorption/ionization (MALDI). Also, the combination of ion mobility separation with laser-based ionization methods starts to gain popularity with access to commercial systems. These developments have been driven mainly by the emergence of new application fields such as MS imaging and non-chromatographic analytical approaches for quantification. This review aims to present these new developments in laser-based methods for the analysis of low-molecular weight compounds by MS and several potential applications. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of various experimental parameters on errors in triangulation solution of elongated object in space. [barium ion cloud

NASA Technical Reports Server (NTRS)

Long, S. A. T.

1975-01-01

The effects of various experimental parameters on the displacement errors in the triangulation solution of an elongated object in space due to pointing uncertainties in the lines of sight have been determined. These parameters were the number and location of observation stations, the object's location in latitude and longitude, and the spacing of the input data points on the azimuth-elevation image traces. The displacement errors due to uncertainties in the coordinates of a moving station have been determined as functions of the number and location of the stations. The effects of incorporating the input data from additional cameras at one of the stations were also investigated.