Three Dimensional Vibration Measurements Using a Five-Axis Scanning Laser Vibrometry System

2007 ◽  
Author(s):  
Patrick F. O’Malley ◽  
John A. Judge ◽  
Joseph F. Vignola
Keyword(s):  
Single Point ◽  
Three Dimensional ◽  
Laser Doppler Vibrometer ◽  
Three Dimensions ◽  
Surface Velocity ◽  
Experimental Facility ◽  
Laser Vibrometry ◽  
Data Set ◽  
Single Beam ◽  
Five Axis

This paper describes an experimental facility designed to measure three-dimensional velocity components using a five-axis laser vibrometry system. A single-point laser Doppler vibrometer (LDV) is mounted on three orthogonal translation stages, and the beam is directed to the target specimen by means of a mirror mounted at the intersection of the axes of two rotational stages. The result is a system with which the vibration of points on the surface of the test specimen can be measured from multiple angles, and these multiple measured components of the surface velocity are combined to determine the full velocity vector in three-dimensions. This system allows collection of a richer data set for more detailed vibration analysis, measurement of vibration of non-planar surfaces, and greater control over measurements compared to conventional single-beam scanning LDV, while greatly reducing experimental facility costs compared with threedimensional LDV systems that use multiple lasers.

scholarly journals Development and assessment of CootVR, a virtual reality computer program for model building

2021 ◽  
Vol 77 (1) ◽  
pp. 19-27
Author(s):  
Hamish Todd ◽  
Paul Emsley
Keyword(s):  
Virtual Reality ◽  
Computer Program ◽  
Model Building ◽  
Three Dimensional ◽  
Specific Model ◽  
Three Dimensions ◽  
Biological Macromolecules ◽  
Data Set ◽  
X Ray Crystallography ◽  
Order Of Magnitude

Biological macromolecules have complex three-dimensional shapes that are experimentally examined using X-ray crystallography and electron cryo-microscopy. Interpreting the data that these methods yield involves building 3D atomic models. With almost every data set, some portion of the time put into creating these models must be spent manually modifying the model in order to make it consistent with the data; this is difficult and time-consuming, in part because the data are `blurry' in three dimensions. This paper describes the design and assessment of CootVR (available at http://hamishtodd1.github.io/cvr), a prototype computer program for performing this task in virtual reality, allowing structural biologists to build molecular models into cryo-EM and crystallographic data using their hands. CootVR was timed against Coot for a very specific model-building task, and was found to give an order-of-magnitude speedup for this task. A from-scratch model build using CootVR was also attempted; from this experience it is concluded that currently CootVR does not give a speedup over Coot overall.

Scanning Laser Doppler Vibrometry of the Middle Ear Ossicles

1997 ◽  
Vol 76 (4) ◽  
pp. 213-222 ◽  
Author(s):  
Geoffrey R. Ball ◽  
Alex Huber ◽  
Richard L. Goode
Keyword(s):  
Middle Ear ◽  
Single Point ◽  
Three Dimensional ◽  
Laser Doppler Vibrometer ◽  
Ossicular Chain ◽  
Laser Doppler ◽  
Scanning Laser ◽  
Scanning Laser Doppler Vibrometer ◽  
Point Analysis ◽  
Ear Ossicles

This paper describes measurements of the vibratory modes of the middle ear ossicles made with a scanning laser Doppler vibrometer. Previous studies of the middle ear ossicles with single-point laser Doppler measurements have raised questions regarding the vibrational modes of the ossicular chain. Single-point analysis methods do not have the ability to measure multiple points on the ossicles and, consequently, have limited ability to simultaneously record relative phase information at these points. Using a Polytec Model PSV-100, detailed measurements of the ossicular chain have been completed in the human temporal bone model. This model, when driven with a middle ear transducer, provides detailed three-dimensional data of the vibrational patterns of the middle ear ossicles. Implications for middle ear implantable devices are discussed.

scholarly journals 3D Magnetic Reconnection

2010 ◽  
Vol 6 (S271) ◽  
pp. 227-238 ◽  
Author(s):  
Clare E. Parnell ◽  
Rhona C. Maclean ◽  
Andrew L. Haynes ◽  
Klaus Galsgaard
Keyword(s):  
Magnetic Reconnection ◽  
Energy State ◽  
Single Point ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Wide Range ◽  
Field Lines ◽  
Magnetohydrodynamic Models ◽  
The Magnetic Field

AbstractMagnetic reconnection is an important process that is prevalent in a wide range of astrophysical bodies. It is the mechanism that permits magnetic fields to relax to a lower energy state through the global restructuring of the magnetic field and is thus associated with a range of dynamic phenomena such as solar flares and CMEs. The characteristics of three-dimensional reconnection are reviewed revealing how much more diverse it is than reconnection in two dimensions. For instance, three-dimensional reconnection can occur both in the vicinity of null points, as well as in the absence of them. It occurs continuously and continually throughout a diffusion volume, as opposed to at a single point, as it does in two dimensions. This means that in three-dimensions field lines do not reconnect in pairs of lines making the visualisation and interpretation of three-dimensional reconnection difficult.By considering particular numerical 3D magnetohydrodynamic models of reconnection, we consider how magnetic reconnection can lead to complex magnetic topologies and current sheet formation. Indeed, it has been found that even simple interactions, such as the emergence of a flux tube, can naturally give rise to ‘turbulent-like’ reconnection regions.

scholarly journals Implementation of a High-Throughput Pilot Screen in Peptide Hydrogel-Based Three-Dimensional Cell Cultures

2019 ◽  
Vol 24 (7) ◽  
pp. 714-723 ◽  
Author(s):  
Peter Worthington ◽  
Katherine M. Drake ◽  
Zhiqin Li ◽  
Andrew D. Napper ◽  
Darrin J. Pochan ◽  
...  
Keyword(s):  
High Throughput ◽  
Single Point ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Culture Cells ◽  
High Throughput Drug Screening ◽  
Cell Culture Systems ◽  
Starting Point ◽  
Pediatric Brain ◽  
Dimensional Cell

Cell-based high-throughput drug screening (HTS) is a common starting point for the drug discovery and development process. Currently, there is a push to combine complex cell culture systems with HTS to provide more clinically applicable results. However, there are mechanistic requirements inherent to HTS as well as material limitations that make this integration challenging. Here, we used the peptide-based shear-thinning hydrogel MAX8 tagged with the RGDS sequence to create a synthetic extracellular scaffold to culture cells in three dimensions and showed a preliminary implementation of the scaffold within an automated HTS setup using a pilot drug screen targeting medulloblastoma, a pediatric brain cancer. A total of 2202 compounds were screened in the 384-well format against cells encapsulated in the hydrogel as well as cells growing on traditional two-dimensional (2D) plastic. Eighty-two compounds passed the first round of screening at a single point of concentration. Sixteen-point dose–response was done on those 82 compounds, of which 17 compounds were validated. Three-dimensional (3D) cell-based HTS could be a powerful screening tool that allows researchers to finely tune the cell microenvironment, getting more clinically applicable data as a result. Here, we have shown the successful integration of a peptide-based hydrogel into the high-throughput format.

Assuring Molded Accuracy of Plastic Involute Worm Gears

2007 ◽  
Author(s):  
Michael T. Weiss ◽  
Roderick E. Kleiss
Keyword(s):  
Single Point ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Error Sources ◽  
Analysis Techniques ◽  
Gear Mesh ◽  
Package Size ◽  
Worm Gears ◽  
High Reduction ◽  
Gear Geometry

Many plastic geared transmissions contain crossed-axis worm drives in the first stage. The purpose is usually to achieve high reduction and/or tailored package size. The need for precision control of worm and helical gear geometry is just as important for this gear mesh as for any other. A myriad of molded flaws can degrade or destroy the performance of these gears. Pitch, tooth thickness, and lead errors are only a few possibilities. Barrel shaped, tapered, or hourglass bodies must be identified and controlled. Asymmetrical teeth are a distinct possibility as well. The only proper way to detect and evaluate these conditions is to scan and analyze these gears in three dimensions. The traditional method of scanning only one section of the tooth on a worm and then scanning the lead at the pitch line will not reveal many molded gear error sources. Measuring pitch or tooth thickness by taking single point measurements around the gear will also miss many errors. We have developed scanning and analysis techniques to accurately map the size and accuracy of these truly three-dimensional involute gear shapes.

Expanding theQ–Rspace to three dimensions

2009 ◽  
Vol 641 ◽  
pp. 497-507 ◽  
Author(s):  
BEAT LÜTHI ◽  
MARKUS HOLZNER ◽  
ARKADY TSINOBER
Keyword(s):  
Velocity Gradient ◽  
Isotropic Turbulence ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Numerical Data ◽  
Three Dimensions ◽  
Data Set ◽  
Viscous Term ◽  
Johns Hopkins University ◽  
Three Dimensional Representation

The two-dimensional space spanned by the velocity gradient invariantsQandRis expanded to three dimensions by the decomposition ofRinto its strain production −1/3sijsjkskiand enstrophy production 1/4ωiωjsijterms. The {Q;R} space is a planar projection of the new three-dimensional representation. In the {Q; −sss; ωωs} space the Lagrangian evolution of the velocity gradient tensorAijis studied via conditional mean trajectories (CMTs) as introduced by Martínet al. (Phys. Fluids, vol. 10, 1998, p. 2012). From an analysis of a numerical data set for isotropic turbulence ofReλ~ 434, taken from the Johns Hopkins University (JHU) turbulence database, we observe a pronounced cyclic evolution that is almost perpendicular to theQ–Rplane. The relatively weak cyclic evolution in theQ–Rspace is thus only a projection of a much stronger cycle in the {Q; −sss; ωωs} space. Further, we find that the restricted Euler (RE) dynamics are primarily counteracted by the deviatoric non-local part of the pressure Hessian and not by the viscous term. The contribution of the Laplacian ofAij, on the other hand, seems the main responsible for intermittently alternating between low and high intensityAijstates.

Sub-Diffraction Limit Three Dimensional Particle Tracking Velocimetry

2013 ◽  
Author(s):  
Craig A. Snoeyink ◽  
Gordon Christopher ◽  
Sourav Barman ◽  
Steve Wereley
Keyword(s):  
Imaging System ◽  
Optical Measurement ◽  
Single Point ◽  
Bessel Beam ◽  
Three Dimensional ◽  
Diffraction Limit ◽  
Point Of View ◽  
Three Dimensions ◽  
Three Dimension ◽  
Single View

Here we present an optical measurement technique and image analysis process capable of tracking particles in three dimensions with a single point of view. In addition to single view 3D-PTV, the optical system is capable of tracking individual particles even at particle-particle spacings that are closer then the diffraction limit of the base imaging system. The measurement system, termed Bessel Beam Microscopy (BBM), functions as an attachment for a microscope that fits between the microscope base and camera. The addition of the BBM attachment transforms the point spread function (PSF) of the microscope allowing two unique functions: single image superresolution imaging, and the extraction of three dimension location information of particles without calibration. The result is a fluid characterization tool with unique capabilities for velocimetry and characterization of the dynamics of dense fluid-particle suspensions.

Three Dimensional Light Microscopy: Imaging & Corrections for Quantitative Analysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 522-523
Author(s):  
J.N. Turner ◽  
W. hain ◽  
D.H. Szarowski ◽  
S. Lasek ◽  
L. Kam ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Light Microscopy ◽  
Three Dimensional ◽  
Image Resolution ◽  
Index Of Refraction ◽  
Three Dimensions ◽  
Objective Lens ◽  
Microscopy Imaging ◽  
Data Set ◽  
Isotropic Resolution

There are several forms of three-dimensional (3-D) light microscopy but all utilize the principle of optical section recording, i.e. the 3-D image is a sequence of two-dimensional (2-D) images called optical sections. The optical sections are particular focal planes formed within the thick specimen and usually correspond to the conventional image projections recorded in a light microscope, referred to as x,y projections. The optical sections are recorded for a sequence of focus- or z-positions. This “stack” of 2-D images is the data set for the 3-D image. If quantitative analysis is to be performed on the 3-D images, the choice of the z-dimension increment between 2-D images is especially important, and its value may be more or less critical depending on the analysis algorithm used. A reasonable starting value for this dimension is the depth-of-field of the objective lens, but the actual value may have to be smaller to optimize the image analysis or larger to decrease the influence of photobleaching. The most photostable dyes should be selected and the specimen should be mounted in index-of-refraction matching media with an antioxidant.The image resolution in all three-dimensions is determined by the 3-D point-spread-function (psf), and as a rough rule of thumb the z-resolution is degraded by a factor of 3 relative to the x,y resolution. To achieve or at least approach isotropic resolution the 3-D image can be deconvolved. Figure 1 shows the 2-D maximum value projection of a 3-D image of a cultured glial cell dual labeled for actin and vinculin before and after deconvolution. The actin fibers and vinculin focal contacts are more clearly resolved after deconvolution. Although a single cultured cell might traditionally be considered a thin object, it is really a thick object if the desired spatial resolution is less than the thickness of the cell. It is desirable to image as deep into a thick object as possible to maximize the tissue volume sampled. However, it has been shown that the image signal decreases with depth into the specimen. Figure 2 demonstrates this effect in a 3-D image of the nuclei of the rat hippocampus that have been labeled with the fluorescent Schiffs reagent acriflavine. In the x,y projection, it is not clear why some nuclei are dimmer than others, but the x,z projection shows that the dimmer ones tend to be deeper in the section. It has been shown that this depth dependent signal attenuation follows the form of an exponential function.

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