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1

2-D Imaging of Electron Temperature in Tokamak Plasmas  

SciTech Connect

By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.

T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol

2004-07-08

2

2D electron temperature diagnostic using soft x-ray imaging technique.  

PubMed

We have developed a two-dimensional (2D) electron temperature (T(e)) diagnostic system for thermal structure studies in a low-aspect-ratio reversed field pinch (RFP). The system consists of a soft x-ray (SXR) camera with two pin holes for two-kinds of absorber foils, combined with a high-speed camera. Two SXR images with almost the same viewing area are formed through different absorber foils on a single micro-channel plate (MCP). A 2D Te image can then be obtained by calculating the intensity ratio for each element of the images. We have succeeded in distinguishing T(e) image in quasi-single helicity (QSH) from that in multi-helicity (MH) RFP states, where the former is characterized by concentrated magnetic fluctuation spectrum and the latter, by broad spectrum of edge magnetic fluctuations. PMID:24689580

Nishimura, K; Sanpei, A; Tanaka, H; Ishii, G; Kodera, R; Ueba, R; Himura, H; Masamune, S; Ohdachi, S; Mizuguchi, N

2014-03-01

3

2D electron temperature diagnostic using soft x-ray imaging technique  

NASA Astrophysics Data System (ADS)

We have developed a two-dimensional (2D) electron temperature (Te) diagnostic system for thermal structure studies in a low-aspect-ratio reversed field pinch (RFP). The system consists of a soft x-ray (SXR) camera with two pin holes for two-kinds of absorber foils, combined with a high-speed camera. Two SXR images with almost the same viewing area are formed through different absorber foils on a single micro-channel plate (MCP). A 2D Te image can then be obtained by calculating the intensity ratio for each element of the images. We have succeeded in distinguishing Te image in quasi-single helicity (QSH) from that in multi-helicity (MH) RFP states, where the former is characterized by concentrated magnetic fluctuation spectrum and the latter, by broad spectrum of edge magnetic fluctuations.

Nishimura, K.; Sanpei, A.; Tanaka, H.; Ishii, G.; Kodera, R.; Ueba, R.; Himura, H.; Masamune, S.; Ohdachi, S.; Mizuguchi, N.

2014-03-01

4

Temperature dependence of Grüneisen parameter in optically absorbing solutions measured by 2D optoacoustic imaging  

NASA Astrophysics Data System (ADS)

A new experimental approach for measurements of temperature dependence of the Grüneisen parameter in optically absorbing solutions is proposed. Two-dimensional optoacoustic (OA) imaging is used to improve accuracy of signal amplitude measurements and spatial localization of the studied samples. We estimated OA response of optically absorbing solutions measuring median intensity of OA images within the region of interest (ROI) as a function of temperature. We showed that when normalized to its value at a particular temperature, OA image intensity becomes an accurate metric reflecting temperature changes of Grüneisen parameter regardless of local optical fluence and absorbance, assuming those remain constant with temperature. Using the proposed method we studied temperature dependence of aqueous solutions of nickel and cupric sulfate in the range from 4 to 40°C. Obtained results were compared with temperature dependence for the Grüneisen parameter of DI-water, which we measured by using carbon ink colloid. We also found that Grüneisen-temperature relationship for nickel sulfate exhibits linear trend with respect to the concentration, and is independent of coupling medium and laser excitation wavelength.In the future, the developed methodology could be adopted for important applications of in vivo optoacoustic temperature monitoring.

Petrova, Elena V.; Ermilov, Sergey A.; Su, Richard; Nadvoretskiy, Vyacheslav; Conjusteau, André; Oraevsky, Alexander A.

2014-03-01

5

LIF imaging and 2D temperature mapping in a model combustor at elevated pressure  

Microsoft Academic Search

Planar laser-induced fluorescence (PLIF) has been used to measure time-resolved spatial distributions of the fuel, the OH radical, and the temperature field in a jet engine model combustor segment. For temperature measurements, a two-line PLIF scheme was used: two different spectral lines of the OH radical, which served as indicator molecule, were excited successively within a short time delay using

Ulrich E. Meier; Dagmar Wolff-Gaßmann; Winfried Stricker

2000-01-01

6

Fast Electron Spatial Temperature Distribution Studied by X-Ray 2D Imaging  

NASA Astrophysics Data System (ADS)

We present the experimental and numerical results of two-dimensional x-ray imaging due to fast electron transport in a solid target. A 40-?m-thick copper film target is irradiated by a 100 mJ, 50 fs normal incident laser pulse. The full width at half maximum of the x-ray photon dose is 25 ?m, and the divergence angle of fast electrons is 25°–30°, which is detected by the pin-hole x-ray imaging technique. The target surface plasma layer is compressed by a ponderomotive force into a depth of 0.2?. The plasma wave accompanied by fast electrons transporting into the target is studied by dividing the plasma into layers in a radial direction. A narrow fast electron channel, which is approximately 8 ?m–10 ?m in width, mainly contributes to the x-ray dose.

Tian, Ye; Wang, Wen-Tao; Xia, Chang-Quan; Wang, Cheng; Xu, Yi; Li, Wen-Tao; Qi, Rong; Zhang, Zhi-Jun; Liang, Hong; Yu, Chang-Hai; Leng, Yu-Xin; Liu, Jian-Sheng

2014-05-01

7

Staring 2-D hadamard transform spectral imager  

DOEpatents

A staring imaging system inputs a 2D spatial image containing multi-frequency spectral information. This image is encoded in one dimension of the image with a cyclic Hadamarid S-matrix. The resulting image is detecting with a spatial 2D detector; and a computer applies a Hadamard transform to recover the encoded image.

Gentry, Stephen M. (Albuquerque, NM); Wehlburg, Christine M. (Albuquerque, NM); Wehlburg, Joseph C. (Albuquerque, NM); Smith, Mark W. (Albuquerque, NM); Smith, Jody L. (Albuquerque, NM)

2006-02-07

8

Laboratory demonstration of high-contrast imaging at 2 ?/D on a temperature-stabilized testbed in air  

NASA Astrophysics Data System (ADS)

Direct imaging of extrasolar planets in visible light, and Earth-like planets in particular, is an exciting but difficult problem requiring a telescope imaging system with 10-10 contrast at separations of 100mas and less. Furthermore, only a small 1-2m space telescope may be realistic for a mission in the foreseeable future, which puts strong demands on the performance of the imaging instrument. Fortunately, an efficient coronagraph called the Phase Induced Amplitude Apodization (PIAA) coronagraph may enable Earth-like planet imaging for such small telescopes if any exist around the nearest stars. In this paper, we report on the latest results from a testbed at the NASA Ames Research Center focused on testing the PIAA coronagraph. This laboratory facility was built in 2008 and is designed to be flexible, operated in a highly stabilized air environment, and to complement efforts at NASA JPL's High Contrast Imaging Testbed. For our wavefront control we are focusing on using small Micro-Electro-Mechanical-System deformable mirrors (MEMS DMs), which promises to reduce the size of the beam and overall instrument, a consideration that becomes very important for small telescopes. In this paper, we briefly describe our lab and methods, including the new active thermal control system, and report the demonstration of 5.4×10-8 average raw contrast in a dark zone from 2.0 - 5.2 ?/D. In addition, we present an analysis of our current limits and solutions to overcome them.

Belikov, Ruslan; Pluzhnik, Eugene; Connelley, Michael S.; Witteborn, Fred C.; Greene, Thomas P.; Lynch, Dana H.; Zell, Peter T.; Guyon, Olivier

2010-07-01

9

Foot measurements from 2D digital images  

Microsoft Academic Search

Foot measurements play an important role in the design of comfortable footwear products. This study proposed a non-invasive and efficient means to obtain foot measurements from 2D digital foot images. The hardware of the proposed image-based measuring system was easy to set up and the developed measuring system was tested for 9 foot measurements with ten male subjects who were

Shuping Xiong; Yulin Li; Yi Zhu; Jingxing Qian; Dong Yang

2010-01-01

10

Image Representation Using 2D Gabor Wavelets  

Microsoft Academic Search

This paper extends to two dimensions the frame criterion developed by Daubechies for one-dimensional wavelets, and itcomputes the frame bounds for the particular case of 2D Gabor wavelets. Completeness criteria for 2D Gabor imagerepresentations are important because of their increasing role in many computer vision applications and also in modeling biologicalvision, since recent neurophysiological evidence from the visual cortex of

Tai Sing Lee

1996-01-01

11

ISAR Target 2D Images Pre-processing in ATR  

Microsoft Academic Search

The recognition performance can be enhanced using the ISAR target 2D image pre-processed. The image consists of many scatters. The image with holes is disadvantageous for extracting features in automatic target recognition (ATR). An approach of ISAR target 2D image pre-processing is proposed. It contains suppressing the interferential stripes, connecting the scatters and normalizing the mass center. The smoothed image

Xinggan Zhang; Yechao Bai

2009-01-01

12

Segmentation of a 2D Image.  

National Technical Information Service (NTIS)

From a multilevel image the authors want to extract the edges of the objects in the scene and transform the image into a symbolic description, that is, a description of the scene as regions, lines and vertices. This transformation consists of several step...

N. J. Langeland

1984-01-01

13

Superquadric-based reconstruction from 2D images  

Microsoft Academic Search

An approach for superquadric-based reconstruction from 2D images is developed, which computes and reconstructs the parametric models of the VE objects from the 2D images of the counterpart real objects. The superquadric-based hierarchical description as the universal parametric description of the 3D objects is proposed. On one hand, according to the complexity of the real objects, the superquadric curves and

Weibin Liu; Chao Zhang; Baozong Yuan

2002-01-01

14

2-D Walsh coding for robust digital image watermarking  

Microsoft Academic Search

One-dimensional (1D) Walsh coding have previously been proposed to improve the robustness of digital image watermarking techniques. In this paper, it is proposed to use two-dimensional (2D) Walsh coding to achieve further improvements in robustness. In the proposed method, Walsh functions are used to perform 2D coding of the watermark before embedding it in the original image. Simulation results, using

A. B. Sewaif; M. Al-Mualla; H. Al-Ahmad

2004-01-01

15

Automatic contour extraction from 2D neuron images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from 2D images of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods cannot be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in presence of

J. J. G. Leandro; R. M. Cesar-Jr; L. da F. Costa

2009-01-01

16

Technical Report - Automatic Contour Extraction from 2D Neuron Images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from 2D images of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods can not be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in presence

J. J. G. Leandro; R. M. Cesar Jr; L. da F. Costa

2008-01-01

17

Technical Report - Automatic Contour Extraction from 2D Neuron Images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from\\u000a2D images of 3D neurons (e.g. camera lucida images and other types of 2D\\u000amicroscopy). Most contour-based shape analysis methods can not be used to\\u000acharacterize such cells because of overlaps between neuronal processes. The\\u000aproposed framework is specifically aimed at the problem of contour following\\u000aeven in presence

J. J. G. Leandro; R. M. Cesar-Jr; F. Costa

2008-01-01

18

Hyperspectral pixels in 2D imaging FPAs?  

NASA Astrophysics Data System (ADS)

Dualband infrared focal plane arrays (FPA), developed for multi-spectral imaging applications, have advantages over conventional multi-FPA sensor configurations in compactness and band-to-band pixel registration. These FPAs have also enabled hyperspectral applications that employ gratings used in two orders, allowing high efficiency hyperspectral imaging over very broad wavelength regions. As time progresses, multi-waveband FPAs are expected to provide an increase in spectral information at the pixel level without the need for external, dispersive optical elements. A variation on this approach, described here, uses detector material of fixed composition, with waveband sensitivity achieved as a function of depth, made possible by the spectral dependence of the absorption coefficient. An increase in the number of wavebands provides hyperspectral capability at the pixel level, hereafter denoted hyperspectral pixel. This technology may someday become possible through advanced detector array architectures, with photons of different wavelength continuously absorbed at different depths, and their resulting photocurrents isolated with a vertical grid of contacts or an equivalent mechanism for transporting depth-dependent signal photocurrent to a read-out circuit unit cell.

Levan, Paul D.; Beecken, Brian P.

2009-08-01

19

Available information in 2D motional Stark effect imaging.  

PubMed

Recent advances in imaging techniques have allowed the extension of the standard polarimetric 1D motional Stark effect (MSE) diagnostic to 2D imaging of the internal magnetic field of fusion devices [J. Howard, Plasma Phys. Controlled Fusion 50, 125003 (2008)]. This development is met with the challenge of identifying and extracting the new information, which can then be used to increase the accuracy of plasma equilibrium and current density profile determinations. This paper develops a 2D analysis of the projected MSE polarization orientation and Doppler phase shift. It is found that, for a standard viewing position, the 2D MSE imaging system captures sufficient information to allow imaging of the internal vertical magnetic field component B(Z)(r,z) in a tokamak. PMID:21033915

Creese, Mathew; Howard, John

2010-10-01

20

Automatic Contour Extraction from 2D Neuron Images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from 2D im- ages of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods can not be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in

Jorge J. G. Leandro; Roberto M. Cesar Jr.; Luciano Da Fontoura Costa

2008-01-01

21

Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images  

NASA Technical Reports Server (NTRS)

VESGEN is a newly automated, user-interactive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling.

Parsons-Wingerter, Patricia; Vickerman, Mary B.; Keith, Patricia A.

2009-01-01

22

2D luminescence imaging of pH in vivo  

PubMed Central

Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields.

Schreml, Stephan; Meier, Robert J.; Wolfbeis, Otto S.; Landthaler, Michael; Szeimies, Rolf-Markus; Babilas, Philipp

2011-01-01

23

Verification of 2D building outlines using oblique airborne images  

NASA Astrophysics Data System (ADS)

Oblique airborne images are interesting not only for visualization but also for the acquisition and updating of geo-spatial vector data. This is because side views of vertical structures, such as buildings, are present in those images. In recent years, techniques for automatic verification of building outlines have been proposed. These techniques utilized color, texture and height from vertical images or range data while oblique images contain façade information that can also be used to identify buildings. This paper presents a methodology to verify 2D building outlines in a cadastral dataset by using oblique airborne images. The method searches for clues such as building edges, wall façade edges and texture. The 2D clues in images taken from different perspectives but expected to contain the same wall are transformed to 3D, combined and used for a verification of the particular wall. Unlike methods that use vertical images or LIDAR, walls are verified individually and then the results are combined for the building. We compare three methods for combining wall-based evidence. Experiments using almost 700 buildings show that best results are obtained using Adaptive Boosting where - with a bias for better identification of demolished buildings - 100% of demolished buildings are identified and 91% of existing buildings are confirmed. The other two methods are Random Trees and a variant of the Dempster-Shafer approach combined with fuzzy reasoning and they only show some minor differences to the Adaptive Boosting result. The research as presented in this paper demonstrates the potential of oblique images, but some further work has to be done, including the identification of modified buildings and the extension towards verification of 3D building models.

Nyaruhuma, Adam Patrick; Gerke, Markus; Vosselman, George; Mtalo, Elifuraha Gerald

2012-07-01

24

Zero-temperature coarsening in the 2d Potts model  

NASA Astrophysics Data System (ADS)

We study the fate of the 2d kinetic q-state Potts model after a sudden quench to zero temperature. Both ground states and complicated static states are reached with non-zero probabilities. These outcomes resemble those found in the quench of the 2d Ising model; however, the variety of static states in the q-state Potts model (with q ? 3) is much richer than in the Ising model, where static states are either ground or stripe states. Another possibility is that the Potts system gets trapped on a set of equal-energy blinker states, where a subset of spins can flip ad infinitum; these states are similar to those found in the quench of the 3d Ising model. The evolution towards the final energy is also unusual—at long times, sudden and massive energy drops may occur that are accompanied by macroscopic reordering of the domain structure. This indeterminacy in the zero-temperature quench of the kinetic Potts model is at odds with basic predictions from the theory of phase-ordering kinetics. We also propose a continuum description of coarsening with more than two equivalent ground states. The resulting time-dependent Ginzburg-Landau equations reproduce the complex cluster patterns that arise in the quench of the kinetic Potts model.

Olejarz, J.; Krapivsky, P. L.; Redner, S.

2013-06-01

25

2D thermography of organic coating behaviors at high temperatures  

NASA Astrophysics Data System (ADS)

In the present work, the thermo-mechanical behavior, temperature versus thermal deformation with respect to time, of different coating films were studied by a non-destructive technique (NDT) known as shearography. Organic coatings, i.e., Epoxy, on metallic alloys, i.e., carbon steels, were investigated at a temperature range simulating the severe weather temperatures in Kuwait especially between the daylight and the night time temperatures. The investigation focused on determining the in-plane displacement of the coatings, which amounts to the thermal deformation and stress with respect to temperature and time. Along with the experimental data, a mathematical relationship was derived describing the thermal deformation and stress of a coating film as a function of temperature. Furthermore, results of shearography indicate that the technique is very useful NDT method not only for determining the thermo-mechanical behavior of different coatings, but also the technique can be used as a 2D-microscope for monitoring the deformation of the coatings in real-time at a microscopic scale.

Habib, Khaled J.; al-Arbeed, Amer

2005-02-01

26

2D Thermal Imaging of the Surfaces of Optoelectronic Devices by Thermoreflectance Microscopy  

Microsoft Academic Search

For the last 40 years, thermoreflectance has been used to experimentally validate bandstructure calculations for semiconductor and metallic materials. The recent development of high resolution thermoreflectance microscopy as a noninvasive, 2D thermal imaging technique, based on measuring the variations of the surface reflectivity with temperature opens new avenues of probing the nanoscale properties of materials and devices. Recently, we have

M. Farzaneh; D. Lüerßen; P. Mayer; R. J. Ram; Janice A. Hudgings

2006-01-01

27

Image Appraisal for 2D and 3D Electromagnetic Inversion  

SciTech Connect

Linearized methods are presented for appraising image resolution and parameter accuracy in images generated with two and three dimensional non-linear electromagnetic inversion schemes. When direct matrix inversion is employed, the model resolution and posterior model covariance matrices can be directly calculated. A method to examine how the horizontal and vertical resolution varies spatially within the electromagnetic property image is developed by examining the columns of the model resolution matrix. Plotting the square root of the diagonal of the model covariance matrix yields an estimate of how errors in the inversion process such as data noise and incorrect a priori assumptions about the imaged model map into parameter error. This type of image is shown to be useful in analyzing spatial variations in the image sensitivity to the data. A method is analyzed for statistically estimating the model covariance matrix when the conjugate gradient method is employed rather than a direct inversion technique (for example in 3D inversion). A method for calculating individual columns of the model resolution matrix using the conjugate gradient method is also developed. Examples of the image analysis techniques are provided on 2D and 3D synthetic cross well EM data sets, as well as a field data set collected at the Lost Hills Oil Field in Central California.

Alumbaugh, D.L.; Newman, G.A.

1999-01-28

28

2-D Drift Velocities from the IMAGE EUV Plasmaspheric Imager  

NASA Technical Reports Server (NTRS)

The IMAGE Mission extreme ultraviolet imager (EUY) observes He+ plasmaspheric ions throughout the inner magnetosphere. Limited by ionizing radiation and viewing close to the Sun, images of the He+ distribution are available every 10 minutes for many hours as the spacecraft passes through apogee in its highly elliptical orbit. As a consistent constituent at about 15%, He+ is an excellent surrogate for monitoring all of the processes that control the dynamics of plasmaspheric plasma. In particular, the motion ofHe+ transverse to the ambient magnetic field is a direct indication of convective electric fields. The analysis of boundary motions has already achieved new insights into the electrodynamic coupling processes taking place between energetic magnetospheric plasmas and the ionosphere. Yet to be fulfilled, however, is the original promise that global EUY images of the plasmasphere might yield two-dimensional pictures of meso-scale to macro-scale electric fields in the inner magnetosphere. This work details the technique and initial application of an IMAGE EUY analysis that appears capable of following thermal plasma motion on a global basis.

Gallagher, D.; Adrian, M.

2007-01-01

29

2-D Drift Velocities from the IMAGE EUV Plasmaspheric Imager  

NASA Technical Reports Server (NTRS)

The IMAGE Mission extreme ultraviolet imager (EW) observes He(+) plasmaspheric ions throughout the inner magnetosphere. Limited by ionizing radiation and viewing close to the Sun, images of the He(+) distribution are available every 10 minutes for many hours as the spacecraft passes through apogee in its highly elliptical orbit. As a consistent constituent at about 15%, He(+) is an excellent surrogate for monitoring all of the processes that control the dynamics of plasmaspheric plasma. In particular, the motion of He' transverse to the ambient magnetic field is a direct indication of convective electric fields. The analysis of boundary motions has already achieved new insights into the electrodynamic coupling processes taking place between energetic magnetospheric plasmas and the ionosphere. Yet to be fulfilled, however, is the original promise that global E W images of the plasmasphere might yield two-dimensional pictures of mesoscale to macro-scale electric fields in the inner magnetosphere. This work details the technique and initial application of an IMAGE EUV analysis that appears capable of following thermal plasma motion on a global basis.

Gallagher, D. L.

2006-01-01

30

2D Genus Topology of 21-cm Differential Brightness Temperature During Cosmic Reionization  

NASA Astrophysics Data System (ADS)

A novel method to characterize the topology of the early-universe intergalactic medium during the epoch of cosmic reionization is presented. The 21-cm radiation background from high redshift is analyzed through calculation of the 2-dimensional (2D) genus. The radiative transfer of hydrogen-ionizing photons and ionization-rate equations are calculated in a suite of numerical simulations under various input parameters. The 2D genus is calculated from the mock 21-cm images of high-redshift universe. We construct the 2D genus curve by varying the threshold differential brightness temperature, and compare this to the 2D genus curve of the underlying density field. We find that (1) the 2D genus curve reflects the evolutionary track of cosmic reionization and (2) the 2D genus curve can discriminate between certain reionization scenarios and thus indirectly probe the properties of radiation-sources. Choosing the right beam shape of a radio antenna is found crucial for this analysis. Square Kilometre Array (SKA) is found to be a suitable apparatus for this analysis in terms of sensitivity, even though some deterioration of the data for this purpose is unavoidable under the planned size of the antenna core.

Hong, Sungwook E.; Ahn, Kyungjin; Park, Changbom; Kim, Juhan; Iliev, Ilian T.; Mellema, Garrelt

2014-04-01

31

High Speed 2D Hadamard Transform Spectral Imager  

SciTech Connect

Hadamard Transform Spectrometer (HTS) approaches share the multiplexing advantages found in Fourier transform spectrometers. Interest in Hadamard systems has been limited due to data storage/computational limitations and the inability to perform accurate high order masking in a reasonable amount of time. Advances in digital micro-mirror array (DMA) technology have opened the door to implementing an HTS for a variety of applications including fluorescent microscope imaging and Raman imaging. A Hadamard transform spectral imager (HTSI) for remote sensing offers a variety of unique capabilities in one package such as variable spectral and temporal resolution, no moving parts (other than the micro-mirrors) and vibration tolerance. Two approaches to for 2D HTS systems have been investigated in this LDRD. The first approach involves dispersing the incident light, encoding the dispersed light then recombining the light. This method is referred to as spectral encoding. The other method encodes the incident light then disperses the encoded light. The second technique is called spatial encoding. After creating optical designs for both methods the spatial encoding method was selected as the method that would be implemented because the optical design was less costly to implement.

WEHLBURG, JOSEPH C.; WEHLBURG, CHRISTINE M.; SMITH, JODY L.; SPAHN, OLGA B.; SMITH, MARK W.; BONEY, CRAIG M.

2003-02-01

32

Mesophases in nearly 2D room-temperature ionic liquids.  

PubMed

Computer simulations of (i) a [C(12)mim][Tf(2)N] film of nanometric thickness squeezed at kbar pressure by a piecewise parabolic confining potential reveal a mesoscopic in-plane density and composition modulation reminiscent of mesophases seen in 3D samples of the same room-temperature ionic liquid (RTIL). Near 2D confinement, enforced by a high normal load, as well as relatively long aliphatic chains are strictly required for the mesophase formation, as confirmed by computations for two related systems made of (ii) the same [C(12)mim][Tf(2)N] adsorbed at a neutral solid surface and (iii) a shorter-chain RTIL ([C(4)mim][Tf(2)N]) trapped in the potential well of part i. No in-plane modulation is seen for ii and iii. In case ii, the optimal arrangement of charge and neutral tails is achieved by layering parallel to the surface, while, in case iii, weaker dispersion and packing interactions are unable to bring aliphatic tails together into mesoscopic islands, against overwhelming entropy and Coulomb forces. The onset of in-plane mesophases could greatly affect the properties of long-chain RTILs used as lubricants. PMID:19886615

Manini, N; Cesaratto, M; Del Pópolo, M G; Ballone, P

2009-11-26

33

Neuro-Fuzzy Based Clustering Approach For Content Based Image Retrieval Using 2D- Wavelet Transform  

Microsoft Academic Search

Abstract—In this paper we introduce neuro-fuzzy based clustering approach for content based image retrieval using 2D-wavelet transform(2D-DWT). Most of the ,image retrieval systems are still incapable of providing retrieval result with high retrieval accuracy and less computational complexity.To address this problem, we developed neural network -fuzzy logic cluster based approach for content based image retrieval using 2D-wavelet transform. The system

V. Balamurugan; P. Anandhakumar

2009-01-01

34

2D color image transmission through a row of optical fibers using optical encoding  

Microsoft Academic Search

This paper presents a new method for 2D image transmission using optical encoding through a row of optical fibers. The basic principle is to encode the 2D image in two different directions by wavelength-multiplexing encoding and time encoding respectively. As the two directions are incoherent, appropriate directions should be chosen to ensure the quality of the 2D image transmission. In

Wenjian Chen; Zeying Chi; Mingjun You; Jianbing Li

1996-01-01

35

A Skew Distortion Correction Method for 2D Bar Code Images Based on Vanishing Points  

Microsoft Academic Search

The skew distortion is the crucial problem that influences the procession for the 2D bar code image recognition. However, as a result of the skew distortion, the vanishing points provide valuable information concerning the camera model used to capture the image. In this paper, a robust and fast algorithm for skew distortion correction in 2D bar code images based on

Xiao-Wei Xu; Zhi-Yan Wang; Yan-Qing Zhang; Ying-Hong Liang

2007-01-01

36

A nonrigid kernel-based framework for 2D-3D pose estimation and 2D image segmentation.  

PubMed

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given shape belongs is given (e.g., cars, boats, or planes). Thus, we propose to solve the 2D-3D pose estimation and 2D image segmentation via nonlinear manifold learning of 3D embedded shapes for a general class of objects or deformations for which one may not be able to associate a skeleton model. Thus, the novelty of our method is threefold: first, we present and derive a gradient flow for the task of nonrigid pose estimation and segmentation. Second, due to the possible nonlinear structures of one's training set, we evolve the pre-image obtained through kernel PCA for the task of shape analysis. Third, we show that the derivation for shape weights is general. This allows us to use various kernels, as well as other statistical learning methodologies, with only minimal changes needing to be made to the overall shape evolution scheme. In contrast with other techniques, we approach the nonrigid problem, which is an infinite-dimensional task, with a finite-dimensional optimization scheme. More importantly, we do not explicitly need to know the interaction between various shapes such as that needed for skeleton models as this is done implicitly through shape learning. We provide experimental results on several challenging pose estimation and segmentation scenarios. PMID:20733218

Sandhu, Romeil; Dambreville, Samuel; Yezzi, Anthony; Tannenbaum, Allen

2011-06-01

37

A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation  

PubMed Central

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given shape belongs is given (e.g., cars, boats, or planes). Thus, we propose to solve the 2D-3D pose estimation and 2D image segmentation via nonlinear manifold learning of 3D embedded shapes for a general class of objects or deformations for which one may not be able to associate a skeleton model. Thus, the novelty of our method is threefold: First, we present and derive a gradient flow for the task of nonrigid pose estimation and segmentation. Second, due to the possible nonlinear structures of one’s training set, we evolve the preimage obtained through kernel PCA for the task of shape analysis. Third, we show that the derivation for shape weights is general. This allows us to use various kernels, as well as other statistical learning methodologies, with only minimal changes needing to be made to the overall shape evolution scheme. In contrast with other techniques, we approach the nonrigid problem, which is an infinite-dimensional task, with a finite-dimensional optimization scheme. More importantly, we do not explicitly need to know the interaction between various shapes such as that needed for skeleton models as this is done implicitly through shape learning. We provide experimental results on several challenging pose estimation and segmentation scenarios.

Sandhu, Romeil; Dambreville, Samuel; Yezzi, Anthony; Tannenbaum, Allen

2013-01-01

38

Shear modulus imaging with 2-D transient elastography  

Microsoft Academic Search

In previous work, we have shown that time-resolved 2-D transient elastography is a promising technique for characterizing the elasticity of soft tissues. It involves the measurement of the displacements induced by the propagation of low frequency (LF) pulsed shear waves in biological tissues. In this paper, we present a novel apparatus that contains a LF vibrating device surrounding a linear

Laurent Sandrin; Mickl Tanter; Stefan Catheline; Mathias Fink

2002-01-01

39

Complete discrete 2-D Gabor transforms by neural networks for image analysis and compression  

Microsoft Academic Search

A three-layered neural network is described for transforming two-dimensional discrete signals into generalized nonorthogonal 2-D Gabor representations for image analysis, segmentation, and compression. These transforms are conjoint spatial\\/spectral representations, which provide a complete image description in terms of locally windowed 2-D spectral coordinates embedded within global 2-D spatial coordinates. In the present neural network approach, based on interlaminar interactions involving

JOHN G. DAUGMAN

1988-01-01

40

Radiology Lab 0: Introduction to 2D and 3D Imaging  

NSDL National Science Digital Library

This is a self-directed learning module to introduce students to basic concepts of imaging technology as well as to give students practice going between 2D and 3D imaging using everyday objects.Annotated: true

Shaffer, Kitt

2008-10-02

41

2-D Time Series Model Based Support Vector Machine for Remote Sensing Image Segmentation  

Microsoft Academic Search

A method of modeling an image based on 2-D Time Series that merges with the popular MultiClass Support Vector Machine (SVM) as a generalized linear classifier is proposed. In this paper, we present the classification results on both remote sensing and texture type images. Both Binary SVM Classifier and Multiclass SVM are implemented and discussed. The 2-D Time Series models

Pei-gee Peter Ho; Chi Hau Chen

2007-01-01

42

Antenna-coupled microbolometer based uncooled 2D array and camera for 2D real-time terahertz imaging  

NASA Astrophysics Data System (ADS)

CEA-Leti has developed a monolithic large focal plane array bolometric technology optimized for 2D real-time imaging in the terahertz range. Each pixel consists in a silicon microbolometer coupled to specific antennas and a resonant quarter-wavelength cavity. First prototypes of imaging arrays have been designed and manufactured for optimized sensing in the 1-3.5THz range where THz quantum cascade lasers are delivering high optical power. NEP in the order of 1 pW/sqrt(Hz) has been assessed at 2.5 THz. This paper reports the steps of this development, starting from the pixel level, to an array associated monolithically to its CMOS ROIC and finally a stand-alone camera. For each step, modeling, technological prototyping and experimental characterizations are presented.

Simoens, F.; Meilhan, J.; Gidon, S.; Lasfargues, G.; Lalanne Dera, J.; Ouvrier-Buffet, J. L.; Pocas, S.; Rabaud, W.; Guellec, F.; Dupont, B.; Martin, S.; Simon, A. C.

2013-09-01

43

On Limits of Embedding in 3D Images Based on 2D Watson's Model  

NASA Astrophysics Data System (ADS)

We extend the Watson image quality metric to 3D images through the concept of integral imaging. In the Watson's model, perceptual thresholds for changes to the DCT coefficients of a 2D image are given for information hiding. These thresholds are estimated in a way that the resulting distortion in the 2D image remains undetectable by the human eyes. In this paper, the same perceptual thresholds are estimated for a 3D scene in the integral imaging method. These thresholds are obtained based on the Watson's model using the relation between 2D elemental images and resulting 3D image. The proposed model is evaluated through subjective tests in a typical image steganography scheme.

Kavehvash, Zahra; Ghaemmaghami, Shahrokh

44

Pulsed laser imaging in practical combustion systems from 2D to 4D  

Microsoft Academic Search

Laser imaging technologies are now being used in practical combustors, from fuel vapour concentration measurements to liquid drop sizing. Simple 2D imagine has demonstrated its capabilities but has limitations in proving all the required data. Multi-dimension and multi-scalar imaging are demonstrating their power in providing additional information. This paper presents the progression of imaging from 2D to 4D and the

James B. Kelman; Glen Sherwood; Frank O'Young; Martin Berckmueller; Mark C. Jermy; Assaad R. Masri; Douglas A. Greenhalgh

2000-01-01

45

Validation of CCHE2D Model Using Digital Image Processing Techniques and Satellite Imagery  

Microsoft Academic Search

This research validates the CCHE2D hydrodynamic model flood simulation results using a series of satellite imagery and several digital image processing techniques. Previously CCHE2D model simulation results have been validated using measured experiment and field channel flow data. In this study, remotely sensed data has been experimented to provide continuous truth data to evaluate the CCHE2D model simulation results for

Azad Hossain; Yafei Jia; Xiabo Chao

46

Hyperspectral image lossless compression using DSC and 2-D CALIC  

Microsoft Academic Search

In recent few years, DSC (Distributed Source Coding) technology is catched much attentions in remote sensing image compression field,due to its excellent performance and low encoding complexity. In this paper, we propose a DSC-based practical solution for hyperspectral image lossless compression system, which applies the DSC technique using the power channel codes of Low-Density-Parity-Check Accumulated(LDPCA) codes and incorporates an efficient

Xueping Yan; Jiaji Wu

2010-01-01

47

Fast visible 2-D camera imaging on NSTX  

NASA Astrophysics Data System (ADS)

Initial applications of 2-D cameras on tokamak devices were mainly used to gain qualitative insight into global dynamics such as plasma formation and motion. Quantitative data were limited, due in large part to the time scales of most plasma events that were far faster than the frame rate of the camera and the inability to resolve structures at the characteristic plasma scale lengths. Recent advances in the development of fast cameras increased the frame rate up to megahertz rates while exposure times as short as 3nsec have been achieved with intensifiers. NSTX supports 8 fast visible cameras with framing rates ranging from 10^3 to 10^6 frames/sec with resolution from 64 X 64 to 1024 X 1080 pixels at the shortest exposure times. These cameras have been used to study plasma phenomena including edge and divertor turbulence, ELMs, and impurity transport. The most recent applications include studies of supersonic gas jets, pellet ablation, incandescent dust behavior, and measurement of fast ion loss of neutral beam injected particles. The capabilities of each camera will be presented and movies of plasma phenomena recorded with them will be presented.

Roquemore, A. L.; Nishino, N.; Maqueda, R.; Bush, C.; Dorf, L.; Shinohara, K.

2005-10-01

48

New applications for the touchscreen in 2D and 3D medical imaging workstations  

Microsoft Academic Search

We present a new interface technique which augments a 3D user interface based on the physical manipulation of tools, or props, with a touchscreen. This hybrid interface intuitively and seamlessly combines 3D input with more traditional 2D input in the same user interface. Example 2D interface tasks of interest include selecting patient images from a database, browsing through axial, coronal,

Ken Hinckley; John C. Goble; Randy Pausch; Neal F. Kassell

1995-01-01

49

New Applications for Touchscreen in 2D and 3D Medical Imaging Workstations  

Microsoft Academic Search

We present a new interface technique which augments a 3D user interface based on the physical manipulation of tools, or props, with a touchscreen. This hybrid interface intuitively and seamlessly combines 3D input with more traditional 2D input in the same user interface. Example 2D interface tasks of interest include selecting patient images from a database, browsing through axial, coronal,

John C. Goble; Ken Hinckley; Neal F. Kassell; Randy Pausch

1995-01-01

50

Detection of sinkholes using 2D electrical resistivity imaging  

Microsoft Academic Search

Sinkholes in dolomitic areas are notoriously difficult geophysical targets, and selecting an appropriate geophysical solution is not straightforward. Electrical resistivity imaging, or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. RESTOM surveys were conducted at two sinkhole sites near Pretoria, South Africa. The survey

Michael van Schoor

2002-01-01

51

Detection of sinkholes using 2D electrical resistivity imaging  

Microsoft Academic Search

Sinkholes in dolomitic areas are notoriously difficult geophysical targets, and selecting an appropriate geophysical solution is not straightforward. Electrical resistivity imaging, or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. RESTOM surveys were conducted at two sinkhole sites near Pretoria, South Africa. The survey

Michael van Schoor

52

2D Detectors for particle physics and for imaging applications  

Microsoft Academic Search

The demands on detectors for particle detection as well as for medical and astronomical X-ray imaging are continuously pushing the development of novel pixel detectors. The state of the art in pixel detector technology to date are hybrid pixel detectors in which sensor and read-out integrated circuits are processed on different substrates and connected via high density interconnect structures. While

H. Krüger

2005-01-01

53

Image appraisal for 2D and 3D electromagnetic inversion  

SciTech Connect

Linearized methods are presented for appraising image resolution and parameter accuracy in images generated with two and three dimensional non-linear electromagnetic inversion schemes. When direct matrix inversion is employed, the model resolution and model covariance matrices can be directly calculated. The columns of the model resolution matrix are shown to yield empirical estimates of the horizontal and vertical resolution throughout the imaging region. Plotting the square root of the diagonal of the model covariance matrix yields an estimate of how the estimated data noise maps into parameter error. When the conjugate gradient method is employed rather than a direct inversion technique (for example in 3D inversion), an iterative method can be applied to statistically estimate the model covariance matrix, as well as a regularization covariance matrix. The latter estimates the error in the inverted results caused by small variations in the regularization parameter. A method for calculating individual columns of the model resolution matrix using the conjugate gradient method is also developed. Examples of the image analysis techniques are provided on a synthetic cross well EM data set.

Alumbaugh, D.L.; Newman, G.A.

1998-04-01

54

Applicability of wave tomography methods for 2-D flow imaging  

Microsoft Academic Search

This paper shows how the technique of acoustic diffraction tomography can be applied to the reconstruction both the magnitudes and directions of velocity vectors as well as to quantitative imaging of refraction inhomogeneities in quasisteady inhomogeneous flows and vortices. It has been stated that nonreciprocity of the sound scattering by flow offers additional information which can be used to carry

Michael N. Rychagov; Helmut Ermert

1994-01-01

55

Localized Iris Image Quality Using 2-D Wavelets  

Microsoft Academic Search

The performance of an iris recognition system can be undermined by poor quality im- ages and result in high false reject rates (FRR) and failure to enroll (FTE) rates. In this paper, a wavelet-based quality measure for iris images is proposed. The merit of the this approach lies in its ability to deliver good spatial adaptivity and determine local quality

Yi Chen; Sarat C. Dass; Anil K. Jain

2006-01-01

56

Adaptive neural network for pattern recognition of 2-D image under affine transformation  

Microsoft Academic Search

Presents a method for recognition of a 2-D image under affine transformation, which can be used as the preprocessing unit in an adaptive neural network. The affine transformation is decomposed into six basic transformations: x-direction and y-direction translations, rotation, x-direction and y-direction expansions (or compressions), and x-direction shear. In order to recognize a 2-D image under affine transformation, the authors

Yiping Chen; Jia-Yuan Han

1991-01-01

57

A 2-D orientation-adaptive prediction filter in lifting structures for image coding  

Microsoft Academic Search

Lifting-style implementations of particular wavelets are popular in image coders. We present a 2-D extension and modification to the prediction part of the lifting implementation type Daubechies 5\\/3 wavelet. The 2-D prediction filter predicts the value of the next polyphase component according to an edge orientation estimator of the image. Consequently, the prediction domain is allowed to rotate + or

Ömer Nezih Gerek; A. Enis Çetin

2006-01-01

58

Automatic lesion detection and segmentation algorithm on 2D breast ultrasound images  

Microsoft Academic Search

Although X-ray mammography (MG) is the dominant imaging modality, ultrasonography (US), with recent advances in technologies, has proven very useful in the evaluation of breast abnormalities. But radiologist should investigate a lot of images for proper diagnosis unlike MG. This paper proposes the automatic algorithm of detecting and segmenting lesions on 2D breast ultrasound images to help radiologist. The detecting

Donghoon Yu; Sooyeul Lee; Jeong Won Lee; Seunghwan Kim

2011-01-01

59

2D Thermal Imaging of the Surfaces of Optoelectronic Devices by Thermoreflectance Microscopy  

NASA Astrophysics Data System (ADS)

For the last 40 years, thermoreflectance has been used to experimentally validate bandstructure calculations for semiconductor and metallic materials. The recent development of high resolution thermoreflectance microscopy as a noninvasive, 2D thermal imaging technique, based on measuring the variations of the surface reflectivity with temperature opens new avenues of probing the nanoscale properties of materials and devices. Recently, we have demonstrated that by utilizing stochastic resonance a thermal resolution of 10mK can be achieved, which exceeds the quantization limit of the camera by two orders of magnitude. Here, we report the use of thermoreflectance to characterize a photonic integrated circuit comprised of cascaded semiconductor optical amplifiers. Optical cooling of the biased amplifiers by 0.5K is observed which demonstrates the high spatial and thermal resolution achievable with stochastic resonance enhanced thermoreflectance microscopy.

Farzaneh, M.; Lüerßen, D.; Mayer, P.; Ram, R. J.; Hudgings, Janice A.

2006-03-01

60

Accurate positioning for head and neck cancer patients using 2D and 3D image guidance  

PubMed Central

Our goal is to determine an optimized image-guided setup by comparing setup errors determined by two-dimensional (2D) and three-dimensional (3D) image guidance for head and neck cancer (HNC) patients immobilized by customized thermoplastic masks. Nine patients received weekly imaging sessions, for a total of 54, throughout treatment. Patients were first set up by matching lasers to surface marks (initial) and then translationally corrected using manual registration of orthogonal kilovoltage (kV) radiographs with DRRs (2D-2D) on bony anatomy. A kV cone beam CT (kVCBCT) was acquired and manually registered to the simulation CT using only translations (3D-3D) on the same bony anatomy to determine further translational corrections. After treatment, a second set of kVCBCT was acquired to assess intrafractional motion. Averaged over all sessions, 2D-2D registration led to translational corrections from initial setup of 3.5 ± 2.2 (range 0–8) mm. The addition of 3D-3D registration resulted in only small incremental adjustment (0.8 ± 1.5 mm). We retrospectively calculated patient setup rotation errors using an automatic rigid-body algorithm with 6 degrees of freedom (DoF) on regions of interest (ROI) of in-field bony anatomy (mainly the C2 vertebral body). Small rotations were determined for most of the imaging sessions; however, occasionally rotations > 3° were observed. The calculated intrafractional motion with automatic registration was < 3.5 mm for eight patients, and < 2° for all patients. We conclude that daily manual 2D-2D registration on radiographs reduces positioning errors for mask-immobilized HNC patients in most cases, and is easily implemented. 3D-3D registration adds little improvement over 2D-2D registration without correcting rotational errors. We also conclude that thermoplastic masks are effective for patient immobilization.

Kang, Hyejoo; Lovelock, Dale M.; Yorke, Ellen D.; Kriminiski, Sergey; Lee, Nancy; Amols, Howard I.

2011-01-01

61

3-D Reconstruction From 2-D Radiographic Images and Its Application to Clinical Veterinary Medicine  

NASA Astrophysics Data System (ADS)

3D imaging technique is very important and indispensable in diagnosis. The main stream of the technique is one in which 3D image is reconstructed from a set of slice images, such as X-ray CT and MRI. However, these systems require large space and high costs. On the other hand, a low cost and small size 3D imaging system is needed in clinical veterinary medicine, for example, in the case of diagnosis in X-ray car or pasture area. We propose a novel 3D imaging technique using 2-D X-ray radiographic images. This system can be realized by cheaper system than X-ray CT and enables to get 3D image in X-ray car or portable X-ray equipment. In this paper, a 3D visualization technique from 2-D radiographic images is proposed and several reconstructions are shown. These reconstructions are evaluated by veterinarians.

Hamamoto, Kazuhiko; Sato, Motoyoshi

62

A new gold-standard dataset for 2D/3D image registration evaluation  

NASA Astrophysics Data System (ADS)

In this paper, we propose a new gold standard data set for the validation of 2D/3D image registration algorithms for image guided radiotherapy. A gold standard data set was calculated using a pig head with attached fiducial markers. We used several imaging modalities common in diagnostic imaging or radiotherapy which include 64-slice computed tomography (CT), magnetic resonance imaging (MRI) using T1, T2 and proton density (PD) sequences, and cone beam CT (CBCT) imaging data. Radiographic data were acquired using kilovoltage (kV) and megavoltage (MV) imaging techniques. The image information reflects both anatomy and reliable fiducial marker information, and improves over existing data sets by the level of anatomical detail and image data quality. The markers of three dimensional (3D) and two dimensional (2D) images were segmented using Analyze 9.0 (AnalyzeDirect, Inc) and an in-house software. The projection distance errors (PDE) and the expected target registration errors (TRE) over all the image data sets were found to be less than 1.7 mm and 1.3 mm, respectively. The gold standard data set, obtained with state-of-the-art imaging technology, has the potential to improve the validation of 2D/3D registration algorithms for image guided therapy.

Pawiro, Supriyanto; Markelj, Primoz; Gendrin, Christelle; Figl, Michael; Stock, Markus; Bloch, Christoph; Weber, Christoph; Unger, Ewald; Nöbauer, Iris; Kainberger, Franz; Bergmeister, Helga; Georg, Dietmar; Bergmann, Helmar; Birkfellner, Wolfgang

2010-03-01

63

Cross-Range Scaling Algorithm for ISAR Images Using 2-D Fourier Transform and Polar Mapping  

Microsoft Academic Search

This paper proposes a new method that solves the problem of inverse synthetic aperture radar image cross-range scaling by estimating the rotational velocity (RV) using the expansion-rotation-scale relationship between two range-Doppler (RD) images. This method is composed of three steps. The first step is preprocessing to construct 2-D Fourier transform images and initial polar-mapped images. In this step, two RD

Sang-Hong Park; Hyo-Tae Kim; Kyung-Tae Kim

2011-01-01

64

3-D\\/2-D Registration of CT and MR to X-ray Images  

Microsoft Academic Search

A crucial part of image-guided therapy is registration of preoperative and intraoperative images, by which the precise position and orientation of the patient's anatomy is determined in three dimensions. This paper presents a novel approach to register three-dimensional (3-D) computed tomography (CT) or magnetic resonance (MR) images to one or more two-dimensional (2-D) X-ray images. The registration is based solely

Dejan Tomazevic; Bostjan Likar; Tomaz Slivnik; Franjo Pernus

2003-01-01

65

2D-1D Wavelet Reconstruction as a Tool for Source Finding in Spectroscopic Imaging Surveys  

NASA Astrophysics Data System (ADS)

Today, image denoising by thresholding of wavelet coefficients is a commonly used tool for 2D image enhancement. Since the data product of spectroscopic imaging surveys has two spatial dimensions and one spectral dimension, the techniques for denoising have to be adapted to this change in dimensionality. In this paper we will review the basic method of denoising data by thresholding wavelet coefficients and implement a 2D-1D wavelet decomposition to obtain an efficient way of denoising spectroscopic data cubes. We conduct different simulations to evaluate the usefulness of the algorithm as part of a source finding pipeline.

Flöer, L.; Winkel, B.

2012-01-01

66

White Matter Changes in Primary Dystonia Determined by 2D Distribution Analysis of Diffusion Tensor Images  

PubMed Central

Purpose To determine brain tissue affected by dystonia by making group comparison of parameter-based diffusion tensor imaging (DTI) distributions of patients with control subjects. A 2D distribution analysis of mean diffusivity and fractional anisotropy index was used for modeling brain tissues according to the inherent diffusion characteristics. Materials and Methods Seven affected carriers of the DYT1 dystonia mutation and eight healthy control subjects were imaged for a previous study. We employed a 2D distribution analysis of all the diffusion voxels and a four compartmental brain model for group comparison of the dystonia subjects and controls. Results Our analysis showed disease involvement in the white matter of the patients. Excellent tissue characterization was achieved automatically using the 2D distribution analysis based on a physical brain model. Conclusion This 2D analysis implicated white matter in dystonia and could be useful as a screening tool in diseases with unknown pathologies.

Vo, An; Eidelberg, David; Ulug, Aziz M.

2014-01-01

67

Space and Time Bounds on Indexing 3D Models from 2D Images  

Microsoft Academic Search

Model-based visual recognition systems often match groups of image features to groups of model features to form initial hypotheses, which are then verified. In order to accelerate recognition considerably, the model groups can be arranged in an index space (hashed) offline such that feasible matches are found by indexing into this space. For the case of 2D images and 3D

David T. Clemens; David W. Jacobs

1991-01-01

68

2D Transducer Array for High-Speed 3D Imaging System.  

National Technical Information Service (NTIS)

3D imaging system was developed utilizing a combination of sparse 2D arrays, the synthetic aperture focusing technique, and coded excitation of a solution for high-speed 3D ultrasound imaging, since it could formulate multiple transmitting beams (as well ...

N. Okada M. Sato C. Ishihara Y. Tamura

2003-01-01

69

Hepatic angiomyolipoma: value of breath hold 2D FLASH GD-dynamic imaging with fat saturation  

Microsoft Academic Search

A case of hepatic angiomyolipoma in a 61-year-old woman is reported. Findings on ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging are presented and the usefulness of breath hold 2D FLASH Gd-dynamic imaging with fat saturation is discussed.

Kazumasa Hayasaka; Shouichi Soeda; Yoshiaki Tanaka; Mitiko Hirayama

1997-01-01

70

Volume estimation from multiplanar 2D ultrasound images using a remote electromagnetic position and orientation sensor  

Microsoft Academic Search

A system is described for calculating volume from a sequence of multiplanar 2D ultrasound images. Ultrasound images are captured using a video digitising card (Hauppauge Win\\/TV card) installed in a personal computer, and regions of interest transformed into 3D space using position and orientation data obtained from an electromagnetic device (Polhemus, Fastrak). The accuracy of the system was assessed by

S. W. Hughes; T. J. D'Arcy; D. J. Maxwell; W. Chiu; A. Milner; J. E. Saunders; R. J. Sheppard

1996-01-01

71

Multiresolution Image Representation Using Combined 2-D and 1-D Directional Filter Banks  

Microsoft Academic Search

In this paper, effective multiresolution image representations using a combination of 2-D filter bank (FB) and directional wavelet transform (WT) are presented. The proposed methods yield simple implementation and low computation costs compared to previous 1-D and 2-D FB combinations or adaptive directional WT methods. Furthermore, they are nonredundant transforms and realize quad-tree like multiresolution representations. In applications on nonlinear

Yuichi Tanaka; Masaaki Ikehara; Truong Q. Nguyen

2009-01-01

72

Crooked-line 2D seismic reflection imaging in crystalline terrains: Part 1, data processing  

Microsoft Academic Search

For cost and access reasons, most of the seismic re- flection data collected in crystalline terrains have been acquired by 2D crooked-line profiling. When the sur- vey geometry is significantly irregular and the geologic structures have cross-profile dip, several standard 2D imaging procedures severely underperform. As a re- sult, reflection signal is poorly aligned across individ- ual common midpoint (CMP)

Mladen R. Nedimovic?; Gordon F. Westz

2003-01-01

73

Finite element simulation and modeling of 2-D arrays for 3-D ultrasonic imaging  

Microsoft Academic Search

Issues of modeling and design of 2-D arrays in three dimensions with finite element code are discussed. These ultrasonic arrays are used for real time dynamic imaging of the heart. Topics include optimization, sensitivity, and performance and methods to speed up the run times required for computer simulations of large three-dimensional models. Empirical results from 45\\\\×45 2-D arrays are also

Ron McKeighen

2001-01-01

74

Interference filter spectral imaging of twilight O+(P-2-D-2) emission  

NASA Astrophysics Data System (ADS)

A spectral imager specifically designed to measure the O(+)(P-2-D-2) emission in the thermosphere during twilight has been constructed and tested in Toronto (43.8 deg N, 79.3 deg W), and found to show promise for long-term and campaign-mode operations . A Modification of the mesopause oxygen rotational temperature imager (MORTI), it consists basically of a narrow-band interference filter (0.144 nm bandwidth) to separate wavelengths as a function of off-axis angle, a lens to focus the spectrum into a series of concentric rings, and a focal plane array (CCD) to record the spectral images in digital form. The instrument was built with two fields of view, one for the zenith and one for 20 deg above the horizon, moveable to track the azimuth of the Sun, in order to provide appropriate data for inversion. Data gathered during June 1991 provided measurments of the column-integrated emission rate with a precision of about 3%. An atomic oxygen profile was deducted that showed good agreement with that predicted by the MSIS-90 model atmosphere. Geomagnetically induced variations of the O(+) lines, calcium spectra resulting from meteor showers, and OH nightglow were also observed.

Ma, Yanhua; Peterson, R. N.; Zhang, S. P.; McDade, I. C.; Wiens, R. H.; Shepherd, G. G.

1995-02-01

75

Problem of twin-image elimination in 2-D computer synthesized hologram  

NASA Astrophysics Data System (ADS)

It is well known that one of the basic functions of security holograms is the maximal complication of their nonauthorized reproduction, in other words - counterfeiting. To solve the problem, concealed images that can be observed only under special conditions are placed into a structure of the hologram. A popular way to place concealed image in Diffractive Optical Variable Device (DOVID) is integration into DOVID's structure of a Concealed Laser-Readable Image (CLRI). Traditionally CLRI is a 2-D Computer-Generated Hologram (2-D CGH), which is a digitized Interference Fringe Data (IFD) structure, computed under the scheme of Fourier-hologram synthesis. Such hologram provides inspection of second level with portable laser reading devices. While it is being read, two (+/- 1 order of diffraction) identical images are formed. In this work a special kind of CGH, which restores image only in one diffractive order or two different images in +1 and -1 orders of diffraction proposed.

Braginets, Eugene; Girnyk, Vladimir; Kostyukevych, Sergey; Soroka, Alexander; Androsyuk, Irina

2007-03-01

76

Non-Zero Temperature analysis of a quasi2D dipolar gas  

NASA Astrophysics Data System (ADS)

We present non-zero Temperature analysis of a quasi2D dipolar gas. To do this, we use the Hartree Fock Bogoliubov (HFB) method within the Popov approximation. This formalism is a set of non-local equations containing the dipole-dipole interaction and the condensate and thermal correlation functions, which are solved self-consistently. We detail the numerical method used to implement the scheme. We present density profiles for a non-zero temperature dipolar gas in q2D, and compare these results to a gas with zero-range interactions. Additionally, we analyze the excitation spectrum.

Ticknor, Christopher

2012-06-01

77

3D surface reconstruction from multiview photographic images using 2D edge contours  

NASA Astrophysics Data System (ADS)

Most techniques for reconstructing 3D shapes from multi-view 2D photographic images require a large number of images. In this paper, we present a new method for reconstructing 3D surfaces, represented by sets of polygons, using a small number, e.g. 10, of 2D photographic images with full prior knowledge of camera configurations. The method is automatic. Unlike most currently available silhouette-based multiview reconstruction methods, 3D surface points and surfaces are reconstructed directly from 2D edges without costly intermediate voxel reconstruction. The surfaces reconstructed by the proposed method are self-optimized. More surface points and polygons are automatically generated on highly curved parts of a surface. Experiments on computer generated objects and real physical objects were conducted to verify the method. [Figure not available: see fulltext.

Prakoonwit, Simant; Benjamin, Ralph

2012-12-01

78

Gated cardiac NMR imaging and 2D echocardiography in the detection of intracardial neoplasm  

SciTech Connect

Noninvasive 2D echocardiography has replaced contrast angiography as the procedure of choice in the diagnosis of intracardiac neoplasm. The purpose of this study was to determine whether intracardiac neoplasm can be detected as well by gated cardiac NMR. Four patients with known intracardiac neoplasm previously diagnosed by 2D echocardiography had gated cardiac NMR imaging using a superconductive 0.6 Tesla magnet. All patients were performed using a Tl weighted spin echo pulse sequence with a TE of 30 msec and TR of one R-R interval. Two-dimensional planar single or multiple slice techniques were used. In one patient, imaging at different times along the R-R interval were performed for cine display. The results of the present study show detection of the intracardiac neoplasm in all four cases by gated cardiac NMR imaging and the results were comparable to 2D echocardiography. The former imaging technique showed superior spatial resolution. Despite its early stage of development, gated cardiac NMR imaging appears at least equal to 2D echocardiography in the detection of intracardiac neoplasm. The availability of multislice coupled with multiframe acquisition techniques now being developed will provide a cinematic display that will be more effective in the display of the tumor in motion within the cardiac chamber involved and facilitate visualization of the relationship of the tumor to adjacent cardiac structures.

Go, R.T.; O'Donnell, J.K.; Salcedo, E.E.; Feiglin, D.H.; Underwood, D.A.; MacIntyre, W.J.; Meaney, T.F.

1985-05-01

79

Tuning the packing density of 2D supramolecular self-assemblies at the solid-liquid interface using variable temperature.  

PubMed

The two-dimensional (2D) crystal engineering of molecular architectures on surfaces requires controlling various parameters related respectively to the substrate, the chemical structure of the molecules, and the environmental conditions. We investigate here the influence of temperature on the self-assembly of hexakis(n-dodecyl)-peri-hexabenzocoronene (HBC-C(12)) adsorbed on gold using scanning tunneling microscopy (STM) at the liquid/solid interface. We show that the packing density of 2D self-assembled HBC-C(12) can be precisely tuned by adjusting the substrate temperature. Increasing the temperature progressively over the 20-50 degrees C range induces three irreversible phase transitions and a 3-fold increase of the packing density from 0.111 to 0.356 molecule/nm(2). High-resolution STM images reveal that this 2D packing density increase arises from the stepwise desorption of the n-dodecyl chains from the gold surface. Such temperature-controlled irreversible phase transitions are thus a versatile tool that can then be used to adjust the packing density of highly ordered functional materials in view of applications in organic electronic devices. PMID:20155970

Marie, Camille; Silly, Fabien; Tortech, Ludovic; Müllen, Klaus; Fichou, Denis

2010-03-23

80

Atherosclerosis imaging using 3D black blood TSE SPACE vs 2D TSE  

PubMed Central

AIM: To compare 3D Black Blood turbo spin echo (TSE) sampling perfection with application-optimized contrast using different flip angle evolution (SPACE) vs 2D TSE in evaluating atherosclerotic plaques in multiple vascular territories. METHODS: The carotid, aortic, and femoral arterial walls of 16 patients at risk for cardiovascular or atherosclerotic disease were studied using both 3D black blood magnetic resonance imaging SPACE and conventional 2D multi-contrast TSE sequences using a consolidated imaging approach in the same imaging session. Qualitative and quantitative analyses were performed on the images. Agreement of morphometric measurements between the two imaging sequences was assessed using a two-sample t-test, calculation of the intra-class correlation coefficient and by the method of linear regression and Bland-Altman analyses. RESULTS: No statistically significant qualitative differences were found between the 3D SPACE and 2D TSE techniques for images of the carotids and aorta. For images of the femoral arteries, however, there were statistically significant differences in all four qualitative scores between the two techniques. Using the current approach, 3D SPACE is suboptimal for femoral imaging. However, this may be due to coils not being optimized for femoral imaging. Quantitatively, in our study, higher mean total vessel area measurements for the 3D SPACE technique across all three vascular beds were observed. No significant differences in lumen area for both the right and left carotids were observed between the two techniques. Overall, a significant-correlation existed between measures obtained between the two approaches. CONCLUSION: Qualitative and quantitative measurements between 3D SPACE and 2D TSE techniques are comparable. 3D-SPACE may be a feasible approach in the evaluation of cardiovascular patients.

Wong, Stephanie K; Mobolaji-Iawal, Motunrayo; Arama, Leron; Cambe, Joy; Biso, Sylvia; Alie, Nadia; Fayad, Zahi A; Mani, Venkatesh

2014-01-01

81

2D bit-parallel flexible optical interconnects using fiber image guides  

Microsoft Academic Search

We propose a flexible 2D bit-parallel optical interconnect method for use in large-bandwidth inter-processor communications. We have studied various possible input\\/output coupling schemes, and have modeled power loss and resolution degradation mechanisms associated with the schemes. We have also performed experiments to investigate the power efficiency and imaging resolution characteristics of the interconnect schemes.

Yao Li; Ting Wang

1996-01-01

82

Fabrication of 2D pH CMOS image sensors and real time imaging of chemical reaction  

Microsoft Academic Search

We present about pH image sensors, which are capable of measuring 2D distribution of various chemical reaction in real time. The pH CMOS image sensor using charge transfer technique is a novel pH sensor and imaging sensor that is capable of measuring variations on the chemical reaction as an image, and it was fabricated by CMOS (complimentary metal-oxide semiconductor) circuit

Takeshi Hizawa; Kazuaki Sawada; Hidekuni Takao; M. lshida

2005-01-01

83

9A-2 Controlled 2D Cardiac Elasticity Imaging on an Isolated Perfused Rabbit Heart  

Microsoft Academic Search

Ultrasound strain and strain rate imaging have been proposed to detect myocardial muscle viability and contractility change. However, it's not easy to control experimental parameters and acquire high SNR data during in-vivo animal experiments. To address this, we performed 2D cardiac elasticity imaging on a well-controlled isolated retroperfused rabbit heart paced through the apex. The excitation-contraction decoupler, 2,3-butanedione monoxime (BDM)

C. Jia; R. Olafsson; K. Kim; R. S. Witte; S.-W. Huang; T. J. Kolias; J. M. Rubin; W. F. Weitzel; C. Deng; M. O'Donnell

2007-01-01

84

2D Seismic Imaging of Elastic Parameters by Frequency Domain Full Waveform Inversion  

Microsoft Academic Search

Thanks to recent advances in parallel computing, full waveform inversion is today a tractable seismic imaging method to reconstruct physical parameters of the earth interior at different scales ranging from the near- surface to the deep crust. We present a massively parallel 2D frequency-domain full-waveform algorithm for imaging visco-elastic media from multi-component seismic data. The forward problem (i.e. the resolution

R. Brossier; J. Virieux; S. Operto

2008-01-01

85

Fiducial-less 2D-3D spine image registration using spine region segmented in CT image  

NASA Astrophysics Data System (ADS)

The target pose (position and orientation) of a spinal lesion can be determined using image registration of a pair of two-dimensional (2D) x-ray projection images and a pre-treatment three-dimensional (3D) CT image. This is useful for detecting, tracking and correcting for patient movement during image-guided spinal radiotherapy and radiosurgery. We recently developed a fiducial-less 2D-3D spine image registration that localizes spinal targets by directly tracking adjacent skeletal structures and thereby eliminates the need for implanted fiducials. Experience has shown this method to be robust under a wide range of clinical circumstances. However, image artifacts in digitally reconstructed radiographs (DRRs) that can be introduced by breathing during CT scanning or by other surrounding structures such as ribs have the negative effects on image registration performance. Therefore, we present an approach to eliminate the image artifacts in DRRs for a more robust registration. The spinal structures in the CT volume are approximately segmented in a semi-automatic way and saved as a volume of interest (VOI). The DRRs are then generated within the spine VOI for two orthogonal projections. During radiation treatment delivery, two X-ray images are acquired simultaneously in near real time. Then each X-ray image is registered with the DRR image to obtain 2D local displacements of skeletal structures. The 3D tumor position is calculated from the 2D displacements by 2D-to-3D back-projection and geometric transformation. Experiments on clinical data were conducted to evaluate the performance of the improved registration. The results showed that spine segmentation substantially improves image registration performance.

Fu, Dongshan; Wang, Hongwu; Maurer, Calvin R., Jr.; Kuduvalli, Gopinath

2007-03-01

86

A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup.  

PubMed

A positioning QA procedure for Varian's 2D/2D (kV/MV) and 3D/3D (planCT/CBCT) matching was developed. The procedure was to check: (1) the coincidence of on-board imager (OBI), portal imager (PI), and cone beam CT (CBCT)'s isocenters (digital graticules) to a linac's isocenter (to a pre-specified accuracy); (2) that the positioning difference detected by 2D/2D (kV/MV) and 3D/3D(planCT/CBCT) matching can be reliably transferred to couch motion. A cube phantom with a 2 mm metal ball (bb) at the center was used. The bb was used to define the isocenter. Two additional bbs were placed on two phantom surfaces in order to define a spatial location of 1.5 cm anterior, 1.5 cm inferior, and 1.5 cm right from the isocenter. An axial scan of the phantom was acquired from a multislice CT simulator. The phantom was set at the linac's isocenter (lasers); either AP MV/R Lat kV images or CBCT images were taken for 2D/2D or 3D/3D matching, respectively. For 2D/2D, the accuracy of each device's isocenter was obtained by checking the distance between the central bb and the digital graticule. Then the central bb in orthogonal DRRs was manually moved to overlay to the off-axis bbs in kV/MV images. For 3D/3D, CBCT was first matched to planCT to check the isocenter difference between the two CTs. Manual shifts were then made by moving CBCT such that the point defined by the two off-axis bbs overlay to the central bb in planCT. (PlanCT can not be moved in the current version of OBI1.4.) The manual shifts were then applied to remotely move the couch. The room laser was used to check the accuracy of the couch movement. For Trilogy (or Ix-21) linacs, the coincidence of imager and linac's isocenter was better than 1 mm (or 1.5 mm). The couch shift accuracy was better than 2 mm. PMID:19918223

Guan, Huaiqun; Hammoud, Rabih; Yin, Fang-Fang

2009-01-01

87

Progressive attenuation fields: Fast 2D-3D image registration without precomputation  

SciTech Connect

Computation of digitally reconstructed radiograph (DRR) images is the rate-limiting step in most current intensity-based algorithms for the registration of three-dimensional (3D) images to two-dimensional (2D) projection images. This paper introduces and evaluates the progressive attenuation field (PAF), which is a new method to speed up DRR computation. A PAF is closely related to an attenuation field (AF). A major difference is that a PAF is constructed on the fly as the registration proceeds; it does not require any precomputation time, nor does it make any prior assumptions of the patient pose or limit the permissible range of patient motion. A PAF effectively acts as a cache memory for projection values once they are computed, rather than as a lookup table for precomputed projections like standard AFs. We use a cylindrical attenuation field parametrization, which is better suited for many medical applications of 2D-3D registration than the usual two-plane parametrization. The computed attenuation values are stored in a hash table for time-efficient storage and access. Using clinical gold-standard spine image data sets from five patients, we demonstrate consistent speedups of intensity-based 2D-3D image registration using PAF DRRs by a factor of 10 over conventional ray casting DRRs with no decrease of registration accuracy or robustness.

Rohlfing, Torsten; Russakoff, Daniel B.; Denzler, Joachim; Mori, Kensaku; Maurer, Calvin R. Jr. [Neuroscience Program, SRI International, Menlo Park, California 94025-3493 (United States); Computer Science Department, Stanford University, Stanford, California 94305-9025 (United States); Chair for Computer Vision, University of Jena, D-07737 Jena (Germany); Department of Media Science, Graduate School of Information Science, Nagoya University, Nagoya, 464-01 (Japan); Department of Neurosurgery, Stanford University, Stanford, California 94305-5327 (United States)

2005-09-15

88

A wavelet relational fuzzy C-means algorithm for 2D gel image segmentation.  

PubMed

One of the most famous algorithms that appeared in the area of image segmentation is the Fuzzy C-Means (FCM) algorithm. This algorithm has been used in many applications such as data analysis, pattern recognition, and image segmentation. It has the advantages of producing high quality segmentation compared to the other available algorithms. Many modifications have been made to the algorithm to improve its segmentation quality. The proposed segmentation algorithm in this paper is based on the Fuzzy C-Means algorithm adding the relational fuzzy notion and the wavelet transform to it so as to enhance its performance especially in the area of 2D gel images. Both proposed modifications aim to minimize the oversegmentation error incurred by previous algorithms. The experimental results of comparing both the Fuzzy C-Means (FCM) and the Wavelet Fuzzy C-Means (WFCM) to the proposed algorithm on real 2D gel images acquired from human leukemias, HL-60 cell lines, and fetal alcohol syndrome (FAS) demonstrate the improvement achieved by the proposed algorithm in overcoming the segmentation error. In addition, we investigate the effect of denoising on the three algorithms. This investigation proves that denoising the 2D gel image before segmentation can improve (in most of the cases) the quality of the segmentation. PMID:24174990

Rashwan, Shaheera; Faheem, Mohamed Talaat; Sarhan, Amany; Youssef, Bayumy A B

2013-01-01

89

A faster method for 3D/2D medical image registration—a simulation study  

NASA Astrophysics Data System (ADS)

3D/2D patient-to-computed-tomography (CT) registration is a method to determine a transformation that maps two coordinate systems by comparing a projection image rendered from CT to a real projection image. Iterative variation of the CT's position between rendering steps finally leads to exact registration. Applications include exact patient positioning in radiation therapy, calibration of surgical robots, and pose estimation in computer-aided surgery. One of the problems associated with 3D/2D registration is the fact that finding a registration includes solving a minimization problem in six degrees of freedom (dof) in motion. This results in considerable time requirements since for each iteration step at least one volume rendering has to be computed. We show that by choosing an appropriate world coordinate system and by applying a 2D/2D registration method in each iteration step, the number of iterations can be grossly reduced from n6 to n5. Here, n is the number of discrete variations around a given coordinate. Depending on the configuration of the optimization algorithm, this reduces the total number of iterations necessary to at least 1/3 of it's original value. The method was implemented and extensively tested on simulated x-ray images of a tibia, a pelvis and a skull base. When using one projective image and a discrete full parameter space search for solving the optimization problem, average accuracy was found to be 1.0 +/- 0.6(°) and 4.1 +/- 1.9 (mm) for a registration in six parameters, and 1.0 +/- 0.7(°) and 4.2 +/- 1.6 (mm) when using the 5 + 1 dof method described in this paper. Time requirements were reduced by a factor 3.1. We conclude that this hardware-independent optimization of 3D/2D registration is a step towards increasing the acceptance of this promising method for a wide number of clinical applications.

Birkfellner, Wolfgang; Wirth, Joachim; Burgstaller, Wolfgang; Baumann, Bernard; Staedele, Harald; Hammer, Beat; Claudius Gellrich, Niels; Jacob, Augustinus Ludwig; Regazzoni, Pietro; Messmer, Peter

2003-08-01

90

A growing 2D spherulite and calculus of variations Part II: A 2D spherulite of polypropylene in a linear temperature field  

Microsoft Academic Search

A 2D spherulite grows in a linear-temperature field from a nucleus of polypropylene at (0,0). The growth lines and the growth fronts are computed by the calculus of variations. The agreement between theory and experiment is satisfactory

G. E. W. Schulze; T. R. Naujeck

1991-01-01

91

Intensity-based registration algorithm for probabilistic images and its application for 2D to 3D image registration  

NASA Astrophysics Data System (ADS)

Registration of 2-D projection images and 3-D volume images is still a largely unsolved problem. In order to register a pre-operative CT image to an intra-operative 2-D x-ray image, one typically computes simulated x-ray images from the attenuation coefficients in the CT image (Digital Reconstructed Radiograph, DRR). The simulated images are then compared to the actual image using intensity-based similarity measures to quantify the correctness of the current relative pose. However, the spatial information present in the CT is lost in the process of computing projections. This paper first introduces a probabilistic extension to the computation of DRRs that preserves much of the spatial separability of tissues along the simulated rays. In order to handle the resulting non-scalar data in intensity-based registration, we propose a way of computing entropy-based similarity measures such as mutual information (MI) from probabilistic images. We give an initial evaluation of the feasibility of our novel image similarity measure for 2-D to 3-D registration by registering a probabilistic DRR to a deterministic DRR computed from patient data used in frameless stereotactic radiosurgery.

Rohlfing, Torsten; Russakoff, Daniel B.; Murphy, Martin J.; Maurer, Calvin R.

2002-05-01

92

Fully automatic 2D to 3D conversion with aid of high-level image features  

NASA Astrophysics Data System (ADS)

With the recent advent in 3D display technology, there is an increasing need for conversion of existing 2D content into rendered 3D views. We propose a fully automatic 2D to 3D conversion algorithm that assigns relative depth values to the various objects in a given 2D image/scene and generates two different views (stereo pair) using a Depth Image Based Rendering (DIBR) algorithm for 3D displays. The algorithm described in this paper creates a scene model for each image based on certain low-level features like texture, gradient and pixel location and estimates a pseudo depth map. Since the capture environment is unknown, using low-level features alone creates inaccuracies in the depth map. Using such flawed depth map for 3D rendering will result in various artifacts, causing an unpleasant viewing experience. The proposed algorithm also uses certain high-level image features to overcome these imperfections and generates an enhanced depth map for improved viewing experience. Finally, we show several 3D results generated with our algorithm in the results section.

Appia, Vikram; Batur, Umit

2014-03-01

93

Resolution enhancement by aerial image approximation with 2D-TCC  

NASA Astrophysics Data System (ADS)

A newly developed sub-resolution assist feature (SRAF) placement technique with two-dimensional transmission cross coefficient (2D-TCC) is described in this paper. In SRAF placement with 2D-TCC, Hopkins' aerial image equation with four-dimensional TCC is decomposed into the sum of Fourier transforms of diffracted light weighted by 2D-TCC, introducing an approximated aerial image so as to place SRAFs into a given reticle layout. SRAFs are placed at peak positions of the approximated aerial image for enhanced resolution. Since the approximated aerial image can handle the full optical model, SRAFs can be automatically optimized to the given optical condition to generate the optimized reticle. The validity of this technique was confirmed by experiment using a Canon FPA6000-ES6a, 248 nm with a numerical aperture (NA) of 0.86. A binary reticle optimized by this technique with mild off-axis illumination was used in the experiment. Both isolated and dense 100 nm contacts (k1 = 0.35) were simultaneously resolved with the aid of this technique.

Yamazoe, Kenji; Sekine, Yoshiyuki; Kawashima, Miyoko; Hakko, Manabu; Ono, Tomomi; Honda, Tokuyuki

2007-10-01

94

Reconfigurable 2D cMUT-ASIC arrays for 3D ultrasound image  

NASA Astrophysics Data System (ADS)

This paper describes the design and implementations of the complete 2D capacitive micromachined ultrasound transducer electronics and its analog front-end module for transmitting high voltage ultrasound pulses and receiving its echo signals to realize 3D ultrasound image. In order to minimize parasitic capacitances and ultimately improve signal-to- noise ratio (SNR), cMUT has to be integrate with Tx/Rx electronics. Additionally, in order to integrate 2D cMUT array module, significant optimized high voltage pulser circuitry, low voltage analog/digital circuit design and packaging challenges are required due to high density of elements and small pitch of each element. We designed 256(16x16)- element cMUT and reconfigurable driving ASIC composed of 120V high voltage pulser, T/R switch, low noise preamplifier and digital control block to set Tx frequency of ultrasound and pulse train in each element. Designed high voltage analog ASIC was successfully bonded with 2D cMUT array by flip-chip bonding process and it connected with analog front-end board to transmit pulse-echo signals. This implementation of reconfigurable cMUT-ASIC-AFE board enables us to produce large aperture 2D transducer array and acquire high quality of 3D ultrasound image.

Song, Jongkeun; Jung, Sungjin; Kim, Youngil; Cho, Kyungil; Kim, Baehyung; Lee, Seunghun; Na, Junseok; Yang, Ikseok; Kwon, Oh-kyong; Kim, Dongwook

2012-02-01

95

Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging  

SciTech Connect

The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology.

Schmidgunst, C.; Ritter, D.; Lang, E. [Siemens AG, Medical Solutions, Special System Division, Allee am Roethelheimpark 2, 91052 Erlangen, Germany and University of Regensburg, Institute for Bio-Physics and Bio-Chemistry, Computational Intelligence and Machine Learning Group, Universitaetsstrasse 31, 93040 Regensburg (Germany); Siemens AG, Medical Solutions, Special System Division, Allee am Roethelheimpark 2, 91052 Erlangen (Germany); University of Regensburg, Institute for Bio-Physics and Bio-Chemistry, Computational Intelligence and Machine Learning Group, Universitaetsstrasse 31, 93040 Regensburg (Germany)

2007-09-15

96

Turbulence study via 2-D microwave imaging reflectometry system on KSTAR  

NASA Astrophysics Data System (ADS)

A microwave imaging reflectometry (MIR) system [1] for KSTAR has been developed to study the turbulence based transport physics based on electron density fluctuation measurement in 2-D (radial and poloidal). Two-frequency source will be introduced for probing two adjacent X-mode cut-off layers, simultaneously. A poloidal array of 16 detectors enables 2-D imaging of the electron density fluctuations of the poloidal cross section. In this paper, test results of the system characteristics such as the spatial coverage and system resolutions using corrugated metal targets in the laboratory will be presented. In addition, descriptions of the two-frequency probing source, optics, detector array, and electronics will be provided. Preliminary measurements of the density fluctuations from 2012 campaign also will be reported.[4pt] [1] H. Park et al, Rev. Sci. Instrum. 74, 4239 (2003).

Lee, Woochang; Leem, J.; Kim, M.; Yun, G. S.; Park, H. K.; Nam, Y.; Kim, Y. G.; Park, H.; Kim, K. W.; Domier, C. W.; Luhmann, N. C., Jr.

2012-10-01

97

Solid H2/D2 Particle Seeding and Injection System for Particle Image Velocimetry (PIV) Measurement of He II  

SciTech Connect

Solid particles of the mixture of hydrogen and deuterium have certain advantages for use in Particle Image Velocimetry (PIV) of He II flow. The H2/D2 particles are near neutrally buoyant in He II and will vaporize with the helium as the experimental apparatus is warmed to room temperature. Progress of the construction of a H2/D2 particle seeding and injection system is reported in this paper. A cryogenic pulse valve is used to inject the mixture of helium, hydrogen and deuterium gas directly into a He II bath. Experiments show that the seeding quality is dependent on the back pressure, the mix ratio of the deuterium and helium gases and valve open duration. The effects of these parameters on the solid deuterium particle distribution are also discussed.

Xu, T.; Van Sciver, S. W. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, 32310 (United States); Mechanical Engineering Department, FAMU-FSU College of Engineering, Tallahassee, Florida, 32310 (United States)

2006-04-27

98

A radiographic imaging system based upon a 2-D silicon microstrip sensor  

Microsoft Academic Search

A high resolution, direct-digital detector system based upon a 2-D silicon microstrip sensor has been designed, built and is undergoing evaluation for applications in dentistry and mammography. The sensor parameters and image requirements were selected using Monte Carlo simulations. Sensors selected for evaluation have a strip pitch of 50 ?m on the p-side and 80 ?m on the n-side. Front-end

A. Papanestis; G. Iles; E. Corrin; M. Raymond; G. Hall; F. Triantis; N. Manthos; I. Evagelou; P. vd Stelt; T. Tarrant; R. Speller; G. Royle

2000-01-01

99

Segmentation of Protein Spots in 2D Gel Electrophoresis Images with Watersheds Using Hierarchical Threshold  

Microsoft Academic Search

\\u000a 2D Gel Electrophoresis (2DGE) image is the most widely used method for the isolation of the objective protein by comparative\\u000a analysis of the protein spot pattern in the gel plane. The process of protein analysis is the method, which compares the protein\\u000a pattern that is spread in the gel plane with the contrast group and finds interesting protein spot by

Youngho Kim; Jung-ja Kim; Yonggwan Won; In Yongho

2003-01-01

100

Exploring 2D\\/3D Input Techniques for Medical Image Analysis  

Microsoft Academic Search

We describe a series of experiments that compared the 2D and 3D input methods for selection and positioning tasks related to medical image analysis. For this study, we chose a switchable P5 glove controller, which can be used to provide both 2DOF and 6DOF input control. Our results suggest that for both tasks the overall completion time and accuracy can

E. Zudilova-Seinstra; P. Sloot; P. de Koning; A. Suinesiaputra; R. van der Geest; J. Reiber

2009-01-01

101

Evaluation of 2D and 3D glove input applied to medical image analysis  

Microsoft Academic Search

We describe a series of experiments that compared 2D\\/3D input methods for selection and positioning tasks related to medical image analysis. For our study, we chose a switchable P5 Glove Controller, which can be used to provide both 2DOF and 6DOF input control. Our results suggest that for both tasks the overall performance and accuracy can be improved when the

Elena V. Zudilova-Seinstra; Patrick J. H. de Koning; Avan Suinesiaputra; Boris W. van Schooten; Rob J. van der Geest; Johan H. C. Reiber; Peter M. A. Sloot

2010-01-01

102

Exploring 2D\\/3D input techniques for medical image analysis  

Microsoft Academic Search

We describe a series of experiments that compared the 2D and 3D input methods for selection and positioning tasks related to medical image analysis. For this study, we chose a switchable P5 glove controller, which can be used to provide both 2DOF and 6DOF input control. Our results suggest that for both tasks the overall completion time and accuracy can

E. V. Zudilova-Seinstra; P. M. A. Sloot; Koning de P. J. H; A. Suinesiaputra; Geest van der R. J; J. H. C. Reiber

2010-01-01

103

Detecting mirror-symmetry of a volumetric shape from its single 2D image  

Microsoft Academic Search

We present a new computational model for verifying whether a 3D shape is mirror-symmetric based on its single 2D image. First, a psychophysical experiment which tested human performance in detection of 3D symmetry is described. These psychophysical results led to the formulation of a new algorithm for symmetry detection. The algorithm first recovers the 3D shape using a priori constraints

Tadamasa Sawada; Zygmunt Pizlo

2008-01-01

104

3D/2D Model-to-Image Registration for Quantitative Dietary Assessment  

PubMed Central

Image-based dietary assessment is important for health monitoring and management because it can provide quantitative and objective information, such as food volume, nutrition type, and calorie intake. In this paper, a new framework, 3D/2D model-to-image registration, is presented for estimating food volume from a single-view 2D image containing a reference object (i.e., a circular dining plate). First, the food is segmented from the background image based on Otsu’s thresholding and morphological operations. Next, the food volume is obtained from a user-selected, 3D shape model. The position, orientation and scale of the model are optimized by a model-to-image registration process. Then, the circular plate in the image is fitted and its spatial information is used as constraints for solving the registration problem. Our method takes the global contour information of the shape model into account to obtain a reliable food volume estimate. Experimental results using regularly shaped test objects and realistically shaped food models with known volumes both demonstrate the effectiveness of our method.

Chen, Hsin-Chen; Jia, Wenyan; Li, Zhaoxin; Sun, Yung-Nien; Sun, Mingui

2013-01-01

105

Night vision image fusion for target detection with improved 2D maximum entropy segmentation  

NASA Astrophysics Data System (ADS)

Infrared and LLL image are used for night vision target detection. In allusion to the characteristics of night vision imaging and lack of traditional detection algorithm for segmentation and extraction of targets, we propose a method of infrared and LLL image fusion for target detection with improved 2D maximum entropy segmentation. Firstly, two-dimensional histogram was improved by gray level and maximum gray level in weighted area, weights were selected to calculate the maximum entropy for infrared and LLL image segmentation by using the histogram. Compared with the traditional maximum entropy segmentation, the algorithm had significant effect in target detection, and the functions of background suppression and target extraction. And then, the validity of multi-dimensional characteristics AND operation on the infrared and LLL image feature level fusion for target detection is verified. Experimental results show that detection algorithm has a relatively good effect and application in target detection and multiple targets detection in complex background.

Bai, Lian-fa; Liu, Ying-bin; Yue, Jiang; Zhang, Yi

2013-08-01

106

Filters in 2D and 3D Cardiac SPECT Image Processing  

PubMed Central

Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast.

Ploussi, Agapi; Synefia, Stella

2014-01-01

107

Multiple-perturbation two-dimensional (2D) correlation analysis for spectroscopic imaging data  

NASA Astrophysics Data System (ADS)

A series of data analysis techniques, including multiple-perturbation two-dimensional (2D) correlation spectroscopy and kernel analysis, were used to demonstrate how these techniques can sort out convoluted information content underlying spectroscopic imaging data. A set of Raman spectra of polymer blends consisting of poly(methyl methacrylate) (PMMA) and polyethylene glycol (PEG) were collected under varying spatial coordinates and subjected to multiple-perturbation 2D correlation analysis and kernel analysis by using the coordinates as perturbation variables. Cross-peaks appearing in asynchronous correlation spectra indicated that the change in the spectral intensity of the free Cdbnd O band of the PMMA band occurs before that of the Cdbnd O⋯Hsbnd O band arising from the molecular interaction between PMMA and PEG. Kernel matrices, generated by carrying out 2D correlation analysis on principal component analysis (PCA) score images, revealed subtle but important discrepancy between the patterns of the images, providing additional interpretation to the PCA in an intuitively understandable manner. Consequently, the results provided apparent spectroscopic evidence that PMMA and PEG in the blends are partially miscible at the molecular level, allowing the PMMAs to respond to the perturbations in different manner.

Shinzawa, Hideyuki; Hashimoto, Kosuke; Sato, Hidetoshi; Kanematsu, Wataru; Noda, Isao

2014-07-01

108

Visualizing 2D Probability Distributions from Satellite Image-Derived Data  

NASA Technical Reports Server (NTRS)

Creating maps of biophysical and geophysical variables using Earth Observing System (EOS) satellite image data is an important component of Earth science. These 2D maps have a single value at every location and standard techniques are used to visualize them. Current tools fall short, however, when it is necessary to describe a distribution of values at each location. Distributions may represent a frequency of occurrence over time, frequency of occurrence from multiple runs of an ensemble forecast or possible values from an uncertainty model. 'Distribution data sets' are described, then a case study is presented to visualize such 2D distributions. Distribution data sets are different from multivariate data sets in the sense that the values are for a single variable instead of multiple variables. Our case study data consists of multiple realizations of percent forest cover, generated using a geostatistical technique that combines ground measurements and satellite imagery to model uncertainty about forest cover. We present several approaches for analyzing and visualizing such data sets. The first is a pixel-wise analysis of the probability density functions for the 2D image while the second is an analysis of features identified within the image. Such pixel-wise and feature-wise views will give Earth scientists a more complete understanding of distribution data sets.

Kao, David; Dungan, Jennifer; Pang, Alex; Biegel, Bryan (Technical Monitor)

2002-01-01

109

Folding of a heterogeneous ?-hairpin peptide from temperature-jump 2D IR spectroscopy  

PubMed Central

We provide a time- and structure-resolved characterization of the folding of the heterogeneous ?-hairpin peptide Tryptophan Zipper 2 (Trpzip2) using 2D IR spectroscopy. The amide I? vibrations of three Trpzip2 isotopologues are used as a local probe of the midstrand contacts, ?-turn, and overall ?-sheet content. Our experiments distinguish between a folded state with a type I? ?-turn and a misfolded state with a bulged turn, providing evidence for distinct conformations of the peptide backbone. Transient 2D IR spectroscopy at 45 °C following a laser temperature jump tracks the nanosecond and microsecond kinetics of unfolding and the exchange between conformers. Hydrogen bonds to the peptide backbone are loosened rapidly compared with the 5-ns temperature jump. Subsequently, all relaxation kinetics are characterized by an observed 1.2 ± 0.2-?s exponential. Our time-dependent 2D IR spectra are explained in terms of folding of either native or nonnative contacts from a common compact disordered state. Conversion from the disordered state to the folded state is consistent with a zip-out folding mechanism.

Jones, Kevin C.; Peng, Chunte Sam; Tokmakoff, Andrei

2013-01-01

110

Comparison of distance measures according to suitability for 2D electrophoresis image registration using synthetic image data and SOFM  

NASA Astrophysics Data System (ADS)

This paper presents a comparative investigation of distance measures that may be used in image registration algorithms specialized for two-dimensional electrophoresis gel images. Standard image registration techniques employ correlationbased similarity measures but they are not robust against geometric and large intensity distortions. Exploitation of specific electrophoresis gel image patterns allows achieving better registration performance. In order to make comparison of distance measures synthetic electrophoresis images were generated. Synthetic data gave ability to control variation of amount of image dissimilarity specific to 2D electrophoresis images. Relation of distance measure response to variation of image dissimilarity was analyzed using self-organizing feature maps. Measures that gave desired responses of self-organizing feature maps were determined. These results were consistent with matching performance of real gel image regions. Computational needs of measures were tested additionally.

Matuzevi?ius, Dalius; Navakauskas, Dalius

2010-06-01

111

2D-CELL: image processing software for extraction and analysis of 2-dimensional cellular structures  

NASA Astrophysics Data System (ADS)

2D-CELL is a software package for the processing and analyzing of photographic images of cellular structures in a largely interactive way. Starting from a binary digitized image, the programs extract the line network (skeleton) of the structure and determine the graph representation that best models it. Provision is made for manually correcting defects such as incorrect node positions or dangling bonds. Then a suitable algorithm retrieves polygonal contours which define individual cells — local boundary curvatures are neglected for simplicity. Using elementary analytical geometry relations, a range of metric and topological parameters describing the population are then computed, organized into statistical distributions and graphically displayed.

Righetti, F.; Telley, H.; Leibling, Th. M.; Mocellin, A.

1992-01-01

112

Spectral-based 2D/3D X-ray to CT image rigid registration  

NASA Astrophysics Data System (ADS)

We present a spectral-based method for the 2D/3D rigid registration of X-ray images to a CT scan. The method uses a Fourier-based representation to decompose the six rigid transformation parameters problem into a twoparameter out-of-plane rotation and a four-parameter in-plane transformation problems. Preoperatively, a set of Digitally Reconstructed Radiographs (DRRs) are generated offline from the CT in the expected in-plane location ranges of the fluoroscopic X-ray imaging devices. Each DRR is transformed into a imaging device in-plane invariant features space. Intraoperatively, a few 2D projections of the patient anatomy are acquired with an X-ray imaging device. Each projection is transformed into its in-plane invariant representation. The out-of-plane parameters are first computed by maximization of the Normalized Cross-Correlation between the invariant representations of the DRRs and the X-ray images. Then, the in-plane parameters are computed with the phase correlation method based on the Fourier-Mellin transform. Experimental results on publicly available data sets show that our method can robustly estimate the out-of-plane parameters with accuracy of 1.5° in less than 1sec for out-of-plane rotations of 10° or more, and perform the entire registration in less than 10secs.

Freiman, M.; Pele, O.; Hurvitz, A.; Werman, M.; Joskowicz, L.

2011-03-01

113

Non-rigid target tracking in 2D ultrasound images using hierarchical grid interpolation  

NASA Astrophysics Data System (ADS)

In this paper, we present a new non-rigid target tracking method within 2D ultrasound (US) image sequence. Due to the poor quality of US images, the motion tracking of a tumor or cyst during needle insertion is considered as an open research issue. Our approach is based on well-known compression algorithm in order to make our method work in real-time which is a necessary condition for many clinical applications. Toward that end, we employed a dedicated hierarchical grid interpolation algorithm (HGI) which can represent a large variety of deformations compared to other motion estimation algorithms such as Overlapped Block Motion Compensation (OBMC), or Block Motion Algorithm (BMA). The sum of squared difference of image intensity is selected as similarity criterion because it provides a good trade-off between computation time and motion estimation quality. Contrary to the others methods proposed in the literature, our approach has the ability to distinguish both rigid and non-rigid motions which are observed in ultrasound image modality. Furthermore, this technique does not take into account any prior knowledge about the target, and limits the user interaction which usually complicates the medical validation process. Finally, a technique aiming at identifying the main phases of a periodic motion (e.g. breathing motion) is introduced. The new approach has been validated from 2D ultrasound images of real human tissues which undergo rigid and non-rigid deformations.

Royer, Lucas; Babel, Marie; Krupa, Alexandre

2014-03-01

114

Breast density measurement: 3D cone beam computed tomography (CBCT) images versus 2D digital mammograms  

NASA Astrophysics Data System (ADS)

Breast density has been recognized as one of the major risk factors for breast cancer. However, breast density is currently estimated using mammograms which are intrinsically 2D in nature and cannot accurately represent the real breast anatomy. In this study, a novel technique for measuring breast density based on the segmentation of 3D cone beam CT (CBCT) images was developed and the results were compared to those obtained from 2D digital mammograms. 16 mastectomy breast specimens were imaged with a bench top flat-panel based CBCT system. The reconstructed 3D CT images were corrected for the cupping artifacts and then filtered to reduce the noise level, followed by using threshold-based segmentation to separate the dense tissue from the adipose tissue. For each breast specimen, volumes of the dense tissue structures and the entire breast were computed and used to calculate the volumetric breast density. BI-RADS categories were derived from the measured breast densities and compared with those estimated from conventional digital mammograms. The results show that in 10 of 16 cases the BI-RADS categories derived from the CBCT images were lower than those derived from the mammograms by one category. Thus, breasts considered as dense in mammographic examinations may not be considered as dense with the CBCT images. This result indicates that the relation between breast cancer risk and true (volumetric) breast density needs to be further investigated.

Han, Tao; Lai, Chao-Jen; Chen, Lingyun; Liu, Xinming; Shen, Youtao; Zhong, Yuncheng; Ge, Shuaiping; Yi, Ying; Wang, Tianpeng; Yang, Wei T.; Shaw, Chris C.

2009-02-01

115

High-temperature electrical behavior of a 2D multilayered MoS2 transistor  

NASA Astrophysics Data System (ADS)

This paper reports the high-temperature-dependent electrical behavior of a 2D multilayer MoS2 transistor. The existence of a big Schottky barrier at the MoS2-Ti junction can reduce carrier transport and lead to a lower transistor conductance. At a high temperature (380 K), the fieldeffect mobility of the multilayer MoS2 transistor increases to 16.9 cm2V-1sec-1, which is 2 times higher than the value at room temperature. These results demonstrate that at high temperature, carrier transport in a MoS2 with a high Schottky barrier is mainly affected by thermionic emission over the energy barrier.

Lee, Yeonsung; Park, Heekyeong; Kwon, Junyeon; Inturu, Omkaram; Kim, Sunkook

2014-04-01

116

A software tool for automatic classification and segmentation of 2D/3D medical images  

NASA Astrophysics Data System (ADS)

Modern medical diagnosis utilizes techniques of visualization of human internal organs (CT, MRI) or of its metabolism (PET). However, evaluation of acquired images made by human experts is usually subjective and qualitative only. Quantitative analysis of MR data, including tissue classification and segmentation, is necessary to perform e.g. attenuation compensation, motion detection, and correction of partial volume effect in PET images, acquired with PET/MR scanners. This article presents briefly a MaZda software package, which supports 2D and 3D medical image analysis aiming at quantification of image texture. MaZda implements procedures for evaluation, selection and extraction of highly discriminative texture attributes combined with various classification, visualization and segmentation tools. Examples of MaZda application in medical studies are also provided.

Strzelecki, Michal; Szczypinski, Piotr; Materka, Andrzej; Klepaczko, Artur

2013-02-01

117

X-Ray Phase-Contrast Imaging with Three 2D Gratings  

PubMed Central

X-ray imaging is of paramount importance for clinical and preclinical imaging but it is fundamentally restricted by the attenuation-based contrast mechanism, which has remained essentially the same since Roentgen's discovery a century ago. Recently, based on the Talbot effect, groundbreaking work was reported using 1D gratings for X-ray phase-contrast imaging with a hospital-grade X-ray tube instead of a synchrotron or microfocused source. In this paper, we report an extension using 2D gratings that reduces the imaging time and increases the accuracy and robustness of phase retrieval compared to current grating-based phase-contrast techniques. Feasibility is demonstrated via numerical simulation.

Jiang, Ming; Wyatt, Christopher Lee; Wang, Ge

2008-01-01

118

Application of 2D tomographic imaging techniques to edge turbulence in RFX-mod  

NASA Astrophysics Data System (ADS)

In the reversed field pinch experiment RFX-mod a gas puffing imaging diagnostic is used to investigate the turbulence of the edge plasma. The system consists of a gas puffing nozzle and 32 optical channels to measure the He I (668 nm) line emission. The lines of sight are arranged into three fans intersecting each other in an area normal to the main magnetic field. The diagnostic system provides an analogue bandwidth of 2 MHz and all channels are simultaneously sampled at 10 Msamples s-1 for the whole discharge duration (350 ms). Different inversion techniques have been applied to the data in order to obtain a 2D tomographic reconstruction of the light emission pattern from the line integrals. Comparison shows that the most precise method is based on the 2D spatial Fourier expansion, applying the singular value decomposition technique with a suitable regularization method to avoid artefacts. The high time resolution allows one to obtain a 2D image every 100 ns. Emission structures ('blobs') that move along the E × B flow emerge from the background turbulence and they are characterized by computing energy and phase of the Fourier modes.

Serianni, Gianluigi; Agostini, Matteo; Cavazzana, Roberto; Scarin, Paolo

2007-12-01

119

2D Tomographic Imaging of the Edge Turbulence in RFX-Mod  

NASA Astrophysics Data System (ADS)

In the reversed Field Pinch Experiment RFX-mod a Gas Puffing Imaging Diagnostic (GPID) is used to investigate the turbulence of the edge plasma. The system consists of a gas puffing nozzle and 32 optical channels to measure the HeI (668 nm) line emission. The lines of sight are arranged into three fans intersecting each other in an area normal to the main magnetic field. The diagnostic system provides an analogue bandwidth of 2 MHz and all channels are simultaneously sampled at 10 MSamples/s for the whole discharge duration (350 ms). Different inversion techniques have been applied to the data in order to obtain a 2D tomographic reconstruction of the light emission pattern from the line integrals. Comparison shows that the most suitable method is based on 2D spatial Fourier expansion, applying the Singular Value Decomposition technique with regularisation. The high sampling time allows to obtain a 2D image every 100 ns. It is found that emission structures (“blobs”) emerge from the background turbulence; a characterisation is given by computing the energy of the Fourier modes.

Serianni, Gianluigi; Cavazzana, Roberto; Agostini, Matteo; Scarin, Paolo

120

Pathways of energy transfer in LHCII revealed by room-temperature 2D electronic spectroscopy.  

PubMed

We present here the first room-temperature 2D electronic spectroscopy study of energy transfer in the plant light-harvesting complex II, LHCII. Two-dimensional electronic spectroscopy has been used to study energy transfer dynamics in LHCII trimers from the chlorophyll b Qy band to the chlorophyll a Qy band. Observing cross-peak regions corresponding to couplings between different excitonic states reveals partially resolved fine structure at the exciton level that cannot be isolated by pump-probe or linear spectroscopy measurements alone. Global analysis of the data has been performed to identify the pathways and time constants of energy transfer. The measured waiting time (Tw) dependent 2D spectra are found to be composed of 2D decay-associated spectra with three timescales (0.3 ps, 2.3 ps and >20 ps). Direct and multistep cascading pathways from the high-energy chlorophyll b states to the lowest-energy chlorophyll a states have been resolved occurring on time scales of hundreds of femtoseconds to picoseconds. PMID:24806660

Wells, Kym L; Lambrev, Petar H; Zhang, Zhengyang; Garab, Gyözö; Tan, Howe-Siang

2014-05-21

121

High-accuracy 2D digital image correlation measurements using low-cost imaging lenses: implementation of a generalized compensation method  

NASA Astrophysics Data System (ADS)

The ideal pinhole imaging model commonly assumed for an ordinary two-dimensional digital image correlation (2D-DIC) system is neither perfect nor stable because of the existence of small out-of-plane motion of the test sample surface that occurred after loading, small out-of-plane motion of the sensor target due to temperature variation of a camera and unavoidable geometric distortion of an imaging lens. In certain cases, these disadvantages can lead to significant errors in the measured displacements and strains. Although a high-quality bilateral telecentric lens has been strongly recommended to be used in the 2D-DIC system as an essential optical component to achieve high-accuracy measurement, it is not generally applicable due to its fixed field of view, limited depth of focus and high cost. To minimize the errors associated with the imperfectness and instability of a common 2D-DIC system using a low-cost imaging lens, a generalized compensation method using a non-deformable reference sample is proposed in this work. With the proposed method, the displacement of the reference sample rigidly attached behind the test sample is first measured using 2D-DIC, and then it is fitted using a parametric model. The fitted parametric model is then used to correct the displacements of the deformed sample to remove the influences of these unfavorable factors. The validity of the proposed compensation method is first verified using out-of-plane translation, out-of-plane rotation, in-plane translation tests and their combinations. Uniaxial tensile tests of an aluminum specimen were also performed to quantitatively examine the strain accuracy of the proposed compensation method. Experiments show that the proposed compensation method is an easy-to-implement yet effective technique for achieving high-accuracy deformation measurement using an ordinary 2D-DIC system.

Pan, Bing; Yu, Liping; Wu, Dafang

2014-02-01

122

Extracting targets from regions-of-interest in infrared images using a 2-D histogram  

NASA Astrophysics Data System (ADS)

We propose an effective method of extracting targets from a region-of-interest (ROI) in infrared images by using a 2-D histogram, considering intensity values and distance values from a center of the ROI. Existing approaches for extracting targets have utilized only intensity values of pixels or an analysis of a 1-D histogram of intensity values. Because the 1-D histogram has mixed bins containing false-negative bins from the target region as well as false-positive bins from the background region, it is difficult to extract target regions effectively due to the mixed bins. In order to solve the problem of the mixed bins, we propose a novel 2-D histogram-based approach for extracting targets. Experimental results have shown that the proposed method achieves better performance of extracting targets than existing methods under various environments, such as target regions with irregular intensities, dim targets, and cluttered backgrounds.

Park, Chan Woo; Lee, Jong Min; Kim, Yong Min; Kim, Yong; Song, Taek Lyul; Park, Ki Tae; Moon, Young Shik

2011-02-01

123

Effective Temperature of 2D Dusty Plasma Liquids at the Discrete Level  

SciTech Connect

Fluctuation-dissipation theory has been used to measure the effective temperature of non-equilibrium system. In this work, using a 2D dusty plasma liquid formed by the negatively charged fine particles suspending in weakly ionized discharges and sheared by two CW counter parallel laser beams, we measure the micro-transport at the kinetic level. The effective temperatures Teff at different time scales are obtained through the Stokes-Einstein relation which relates the diffusion coefficient (D) and the viscosity ({eta}). The external energy is cascaded from the slow hopping modes to the fast caging modes through mutual coupling, which leads to the higher effective temperature of the slow hopping modes.

Io, C.-W.; Chan, C.-L.; I Lin [Department of Physics, National Central University, Jhongli 32001, Taiwan (China)

2007-07-13

124

2D and 3D visualization methods of endoscopic panoramic bladder images  

NASA Astrophysics Data System (ADS)

While several mosaicking algorithms have been developed to compose endoscopic images of the internal urinary bladder wall into panoramic images, the quantitative evaluation of these output images in terms of geometrical distortions have often not been discussed. However, the visualization of the distortion level is highly desired for an objective image-based medical diagnosis. Thus, we present in this paper a method to create quality maps from the characteristics of transformation parameters, which were applied to the endoscopic images during the registration process of the mosaicking algorithm. For a global first view impression, the quality maps are laid over the panoramic image and highlight image regions in pseudo-colors according to their local distortions. This illustration supports then surgeons to identify geometrically distorted structures easily in the panoramic image, which allow more objective medical interpretations of tumor tissue in shape and size. Aside from introducing quality maps in 2-D, we also discuss a visualization method to map panoramic images onto a 3-D spherical bladder model. Reference points are manually selected by the surgeon in the panoramic image and the 3-D model. Then the panoramic image is mapped by the Hammer-Aitoff equal-area projection onto the 3-D surface using texture mapping. Finally the textured bladder model can be freely moved in a virtual environment for inspection. Using a two-hemisphere bladder representation, references between panoramic image regions and their corresponding space coordinates within the bladder model are reconstructed. This additional spatial 3-D information thus assists the surgeon in navigation, documentation, as well as surgical planning.

Behrens, Alexander; Heisterklaus, Iris; Müller, Yannick; Stehle, Thomas; Gross, Sebastian; Aach, Til

2011-03-01

125

Automatic lesion detection and segmentation algorithm on 2D breast ultrasound images  

NASA Astrophysics Data System (ADS)

Although X-ray mammography (MG) is the dominant imaging modality, ultrasonography (US), with recent advances in technologies, has proven very useful in the evaluation of breast abnormalities. But radiologist should investigate a lot of images for proper diagnosis unlike MG. This paper proposes the automatic algorithm of detecting and segmenting lesions on 2D breast ultrasound images to help radiologist. The detecting part is based on the Hough transform with downsampling process which is very efficient to sharpen the smooth lesion boundary and also to reduce the noise. In segmenting part, radial dependent contrast adjustment (RDCA) method is newly proposed. RDCA is introduced to overcome the limitation of Gaussian constraint function. It decreases contrast around the center of lesion but increases contrast proportional to the distance from the center of lesion. As a result, segmentation algorithm shows robustness in various shapes of lesion. The proposed algorithms may help to detect lesions and to find boundary of lesions efficiently.

Yu, Donghoon; Lee, Sooyeul; Lee, Jeong Won; Kim, Seunghwan

2011-03-01

126

Color CCD Temperature Imaging  

Microsoft Academic Search

This paper present the calibration method of color CCD temperature measurement system based on image processing according to bicolorimetric method. According to the experimental results, the relation between red, green and blue brightness is established. This method is employed to calculate temperature. The calculated result shows that the relative errors are small by this method. It is a fundamental work

Rongbao Chen; Kun Wang; Minrui Fei

2009-01-01

127

Multilevel hybrid 2D strain imaging algorithm for ultrasound sector/phased arrays.  

PubMed

Two-dimensional (2D) cross-correlation algorithms are necessary to estimate local displacement vector information for strain imaging. However, most of the current two-dimensional cross-correlation algorithms were developed for linear array transducers. Although sector and phased array transducers are routinely used for clinical imaging of abdominal and cardiac applications, strain imaging for these applications has been performed using one-dimensional (1D) cross-correlation analysis. However, one-dimensional cross-correlation algorithms are unable to provide accurate and precise strain estimation along all the angular insonification directions which can range from -45 degrees to 45 degrees with sector and phased array transducers. In addition, since sector and phased array based images have larger separations between beam lines as the pulse propagates deeper into tissue, signal decorrelation artifacts with deformation or tissue motion are more pronounced. In this article, the authors propose a multilevel two-dimensional hybrid algorithm for ultrasound sector and phased array data that demonstrate improved tracking and estimation performance when compared to the traditional 1D cross-correlation or 2D cross-correlation based methods. Experimental results demonstrate that the signal-to-noise and contrast-to-noise ratio estimates improve significantly for smaller window lengths for the hybrid method when compared to the currently used one-dimensional or two-dimensional cross-correlation algorithms. Strain imaging results on ex vivo thermal lesions created in liver tissue and in vivo on cardiac short-axis views demonstrate the improved image quality obtained with this method. PMID:19610299

Chen, Hao; Varghese, Tomy

2009-06-01

128

Cardiac cycle phase estimation in 2-D echocardiographic images using an artificial neural network.  

PubMed

This paper proposes a new hybrid approach to estimate the cardiac cycle phases in 2-D echocardiographic images as a first step in cardiac volume estimation. We focused on analyzing the atrial systole and diastole events by using the geometrical position of the mitral valve and a set of three image features. The proposed algorithm is based on a tandem of image processing methods and artificial neural networks as a classifier to robustly extract anatomical information. An original set of image features is proposed and derived to recognize the cardiac phases. The aforementioned approach is performed in two denoising scenarios. In the first scenario, the images are corrupted with Gaussian noise, and in the second one with Rayleigh noise distribution. Our hybrid algorithm does not involve any manual tracing of the boundaries for segmentation process. The algorithm is implemented as computer-aided diagnosis (CADi) software. A dataset of 150 images that include both normal and infarct cardiac pathologies was used. We reported an accuracy of 90 % and a 2 ± 0.3 s in terms of execution time of CADi application in a cardiac cycle estimation task. The main contribution of this paper is to propose this hybrid method and a set of image features that can be helpful for automatic detection applications without any user intervention. The results of the employed methods are qualitatively and quantitatively compared in terms of efficiency for both scenarios. PMID:23247838

Bibicu, Dorin; Moraru, Luminita

2013-05-01

129

Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer  

NASA Astrophysics Data System (ADS)

A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.

Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.

2011-02-01

130

2D XFEM-Based Modeling of Retraction and Successive Resections for Preoperative Image Update  

PubMed Central

We consider the problem of improving outcomes for neurosurgery patients by enhancing intraoperative navigation and guidance. Currently intraoperative navigation systems do not accurately account for brain shift or for tissue resection. In this paper, we describe how preoperative images are incrementally updated to take into account any type of brain tissue deformation that can occur during surgery, and thus to improve the accuracy of image-guided navigation systems. For this purpose, we develop a nonrigid image registration technique using on a biomechanical model, which deforms based on the Finite Element Method (FEM). While FEM has been successfully used for dealing with deformation such as brain shift, FEM has difficulties dealing with tissue discontinuities. Here, we describe the novel application of the eXtended Finite Element Method (XFEM) in the field of image-guided surgery, in order to model brain deformations that imply tissue discontinuities. In particular, this paper presents a detailed account of the use of XFEM for dealing with retraction and successive resections, and demonstrates the feasibility of the approach by considering 2D examples based on intraoperative MR images. For evaluating our results, we compute the modified Hausdorff distance between Canny edges extracted from images before and after registration. We show that this distance decreases after registration, and thus demonstrate that our approach improves alignment of intraoperative images.

Vigneron, Lara M.; Duflot, Marc P.; Robe, Pierre A.; Warfield, Simon K.; Verly, Jacques G.

2013-01-01

131

2D XFEM-based modeling of retraction and successive resections for preoperative image update.  

PubMed

This paper considers an approach to improving outcomes for neurosurgery patients by enhancing intraoperative navigation and guidance. Currently, intraoperative navigation systems do not accurately account for brain shift or tissue resection. We describe how preoperative images can be incrementally updated to take into account any type of brain tissue deformation that may occur during surgery, and thus to improve the accuracy of image-guided navigation systems. For this purpose, we have developed a non-rigid image registration technique using a biomechanical model, which deforms based on the Finite Element Method (FEM). While the FEM has been used successfully for dealing with deformations such as brain shift, it has difficulty with tissue discontinuities. Here, we describe a novel application of the eXtended Finite Element Method (XFEM) in the field of image-guided surgery in order to model brain deformations that imply tissue discontinuities. In particular, this paper presents a detailed account of the use of XFEM for dealing with retraction and successive resections, and demonstrates the feasibility of the approach by considering 2D examples based on intraoperative MR images. To evaluate our results, we compute the modified Hausdorff distance between Canny edges extracted from images before and after registration. We show that this distance decreases after registration, and thus demonstrate that our approach improves alignment of intraoperative images. PMID:19634040

Vigneron, Lara M; Duflot, Marc P; Robe, Pierre A; Warfield, Simon K; Verly, Jacques G

2009-01-01

132

Visualizing 3D Objects from 2D Cross Sectional Images Displayed "In-Situ" versus "Ex-Situ"  

ERIC Educational Resources Information Center

The present research investigates how mental visualization of a 3D object from 2D cross sectional images is influenced by displacing the images from the source object, as is customary in medical imaging. Three experiments were conducted to assess people's ability to integrate spatial information over a series of cross sectional images in order to…

Wu, Bing; Klatzky, Roberta L.; Stetten, George

2010-01-01

133

GPU accelerated generation of digitally reconstructed radiographs for 2-D/3-D image registration.  

PubMed

Recent advances in programming languages for graphics processing units (GPUs) provide developers with a convenient way of implementing applications which can be executed on the CPU and GPU interchangeably. GPUs are becoming relatively cheap, powerful, and widely available hardware components, which can be used to perform intensive calculations. The last decade of hardware performance developments shows that GPU-based computation is progressing significantly faster than CPU-based computation, particularly if one considers the execution of highly parallelisable algorithms. Future predictions illustrate that this trend is likely to continue. In this paper, we introduce a way of accelerating 2-D/3-D image registration by developing a hybrid system which executes on the CPU and utilizes the GPU for parallelizing the generation of digitally reconstructed radiographs (DRRs). Based on the advancements of the GPU over the CPU, it is timely to exploit the benefits of many-core GPU technology by developing algorithms for DRR generation. Although some previous work has investigated the rendering of DRRs using the GPU, this paper investigates approximations which reduce the computational overhead while still maintaining a quality consistent with that needed for 2-D/3-D registration with sufficient accuracy to be clinically acceptable in certain applications of radiation oncology. Furthermore, by comparing implementations of 2-D/3-D registration on the CPU and GPU, we investigate current performance and propose an optimal framework for PC implementations addressing the rigid registration problem. Using this framework, we are able to render DRR images from a 256×256×133 CT volume in ~24 ms using an NVidia GeForce 8800 GTX and in ~2 ms using NVidia GeForce GTX 580. In addition to applications requiring fast automatic patient setup, these levels of performance suggest image-guided radiation therapy at video frame rates is technically feasible using relatively low cost PC architecture. PMID:22801484

Dorgham, Osama M; Laycock, Stephen D; Fisher, Mark H

2012-09-01

134

A multiple-point statistics algorithm for 3D pore space reconstruction from 2D images  

NASA Astrophysics Data System (ADS)

Fluid flow behavior in a porous medium is a function of the geometry and topology of its pore space. The construction of a three dimensional pore space model of a porous medium is therefore an important first step in characterizing the medium and predicting its flow properties. A stochastic technique for reconstruction of the 3D pore structure of unstructured random porous media from a 2D thin section training image is presented. The proposed technique relies on successive 2D multiple point statistics simulations coupled to a multi-scale conditioning data extraction procedure. The Single Normal Equation Simulation Algorithm (SNESIM), originally developed as a tool for reproduction of long-range, curvilinear features of geological structures, serves as the simulation engine. Various validating criteria such as marginal distributions of pore and grain, directional variograms, multiple-point connectivity curves, single phase effective permeability and two phase relative permeability calculations are used to analyze the results. The method is tested on a sample of Berea sandstone for which a 3D micro-CT scanning image is available. The results confirm that the equi-probable 3D realizations obtained preserve the typical patterns of the pore space that exist in thin sections, reproduce the long-range connectivities, capture the characteristics of anisotropy in both horizontal and vertical directions and have single and two phase flow characteristics consistent with those of the measured 3D micro-CT image.

Hajizadeh, Alireza; Safekordi, Aliakbar; Farhadpour, Farhad A.

2011-10-01

135

2-D Locally Regularized Tissue Strain Estimation From Radio-Frequency Ultrasound Images: Theoretical Developments and Results on Experimental Data  

Microsoft Academic Search

In this paper, a 2-D locally regularized strain estimation method for imaging deformation of soft biological tissues from radio-frequency (RF) ultrasound (US) data is introduced. Contrary to most 2-D techniques that model the compression-induced local displacement as a 2-D shift, our algorithm also considers a local scaling factor in the axial direction. This direction-dependent model of tissue motion and deformation

Elisabeth Brusseau; Jan Kybic; Jean-françois Deprez; Olivier Basset

2008-01-01

136

Calibration and simulation of ASM2d at different temperatures in a phosphorus removal pilot plant.  

PubMed

In this work, an organic and nutrient removal pilot plant was used to study the temperature influence on phosphorus accumulating organisms. Three experiments were carried out at 13, 20 and 24.5 degrees C, achieving a high phosphorus removal percentage in all cases. The ASM2d model was calibrated at 13 and 20 degrees C and the Arrhenius equation constant was obtained for phosphorus removal processes showing that the temperature influences on the biological phosphorus removal subprocesses in a different degree. The 24.5 degrees C experiment was simulated using the model parameters obtained by means of the Arrhenius equation. The simulation results for the three experiments showed good correspondence with the experimental data, demonstrating that the model and the calibrated parameters were able to predict the pilot plant behaviour. PMID:16889256

García-Usach, F; Ferrer, J; Bouzas, A; Seco, A

2006-01-01

137

2D aperture synthesis for Lamb wave imaging using co-arrays  

NASA Astrophysics Data System (ADS)

2D ultrasonic arrays in Lamb wave based SHM systems can operate in the phased array (PA) or synthetic focusing (SF) mode. In the real-time PA approach, multiple electronically delayed signals excite transmitting elements to form the desired wave-front, whereas receiving elements are used to sense scattered waves. Due to that, the PA mode requires multi channeled hardware and multiple excitations at numerous azimuths to scan the inspected region of interest. To the contrary, the SF mode, assumes a single element excitation of subsequent transmitters and off-line processing of the acquired data. In the simplest implementation of the SF technique, a single multiplexed input and output channels are required, which results in significant hardware simplification. Performance of a 2D imaging array depends on many parameters, such as, its topology, number of its transducers and their spacing in terms of wavelength as well as the type of weighting function (apodization). Moreover, it is possible to use sparse arrays, which means that not all array elements are used for transmitting and/ or receiving. In this paper the co-array concept is applied to facilitate the synthesis process of an array's aperture used in the multistatic synthetic focusing approach in Lamb waves-based imaging systems. In the coherent imaging, performed in the transmit/receive mode, the sum co-array is a morphological convolution of the transmit/receive sub-arrays. It can be calculated as the set of sums of the individual elements' locations in the sub-arrays used for imaging. The coarray framework will be presented here using two different array topologies, aID uniform linear array and a cross-shaped array that will result in a square coarray. The approach will be discussed in terms of array patterns and beam patterns of the resulting imaging systems. Both, theoretical and experimental results will be given.

Ambrozinski, Lukasz; Stepinski, Tadeusz; Uhl, Tadeusz

2014-03-01

138

The 2D-Micro Hole & Strip Plate in CF4 atmosphere aiming neutron imaging  

NASA Astrophysics Data System (ADS)

The Micro Hole & Strip Plate (MHSP) achieves gains above 300 in tetrafluoromethane (CF4) at 2.6 bar, making it suitable for neutron detection. Over the past few years, the imaging capabilities of the MHSP have been developed, leading to the 2D-MHSP. In this device, the position coordinates are determined using the principle of resistive charge division. The GEM-side was specially patterned in strips interconnected by a resistive strip for one of the coordinates and, in the MS-side, the anode strips were also interconnected by another resistive strip. By applying a trivial center of mass algorithm it is possible to obtain both coordinates and the energy of each detected event. The ability to register position and energy for each event can be very useful for event validation in neutron detection. In this work, the performance of the 2D-MHSP in CF4 is investigated. The Modular Transfer Function (MTF) is presented, showing that position resolutions of 700?m in x and 1 mm in the y-direction are obtained with X-rays. It is also demonstrated that resolutions below the proton range (1 mm) are possible at 2.6 bar CF4, demonstrating that the MHSP can be a cost effective choice for neutron imaging.

Natal da Luz, H.; Gouvêa, A. L.; Mir, J. A.; dos Santos, J. M. F.; Veloso, J. F. C. A.

2009-12-01

139

Low-temperature studies of a 2D Quantum Heisenberg Antiferromagnet  

NASA Astrophysics Data System (ADS)

A recent inelastic neutron scattering experiment of a 2D Quantum Heisenberg Antiferromagnet (2DQHAF) in an applied field [1] revealed novel features in the energy spectrum but the field was limited to 0.3 HSAT due to the exchange strength (J = 17.5 K) of the material under study. (Quinolinium)2CuBr4.2H2O is known [2] to be a molecular-based version of a strongly 2D QHAF with a significantly smaller exchange strength of 6.2 K and a saturation field of 15 T. We report the low-temperature properties (T 1.8 K) of (Quinolinium)2CuBr4.2H2O and discuss its applicability for further investigations.[4pt] [1] N. Tsyrulin, T. Pardina, R. R. P. Singh et al, Phys. Rev. Lett. 102, 197201: 1-4 (2009).[0pt] [2] R. T. Butcher, M. M. Turnbull, C. P. Landee et al, Inorg. Chem. 49, 427-434 (2010).

Landee, Christopher; Xiao, Fan; Turnbull, Mark; Bartolomé, Juan

2013-03-01

140

Strongly Temperature-dependent Compressibility of Dilute 2D Holes near the Metal-Insulator Transition  

NASA Astrophysics Data System (ADS)

We used the capacitance measurement to study the compressibility of dilute 2D holes in a 10nm wide GaAs quantum well for T=0.01-0.7K. The sample exhibits the B=0 metal-insulator transition (MIT) at a critical density pc˜ 1.0 x 10^10 /cm^2. Deep in the metallic state, the sample capacitance decreases slowly as hole density p increases, due to the (negative) exchange contribution to the compressibility of an interacting 2D system. As p is reduced below pc at low-T, the capacitance of sample diminishes rapidly as a result of the incompressible nature of the insulator state, similar to previous studies (Dultz and Jiang, PRL 84, 4689 (2000); Allison et al., PRL 96, 216407 (2006)). On the other hand, we found that temperature has a strong effect near the MIT, in contrast to literature. In our system, the compressibility of insulator state increases with T and remains positive, while the behavior of metallic phase is more complex. Notably, for metallic phase with p slightly above pc, the sign of compressibility can change from positive to negative as T increases. This strongly T-dependent compressibility is possibly related to the competition between two phases with distinctive compressibility in our system, which is more strongly interacting than samples studied previously.

Gao, Xuan; Masuhara, Naoto; Boebinger, Greg; Pfeiffer, Loren

2009-03-01

141

2-D Registration and 3-D Shape Inference of the Retinal Fundus from Fluorescein Images  

PubMed Central

This study presents methods to 2-D registration of retinal image sequences and 3-D shape inference from fluorescein images. The Y-feature is a robust geometric entity that is largely invariant across modalities as well as across the temporal grey level variations induced by the propagation of the dye in the vessels. We first present a Y-feature extraction method that finds a set of Y-feature candidates using local image gradient information. A gradient-based approach is then used to align an articulated model of the Y-feature to the candidates more accurately while optimizing a cost function. Using mutual information, fitted Y-features are subsequently matched across images, including colors and fluorescein angiographic frames, for registration. To reconstruct the retinal fundus in 3-D, the extracted Y-features are used to estimate the epipolar geometry with a plane-and-parallax approach. The proposed solution provides a robust estimation of the fundamental matrix suitable for plane-like surfaces, such as the retinal fundus. The mutual information criterion is used to accurately estimate the dense disparity map, while the Y-features are used to estimate the bounds of the range space. Our experimental results validate the proposed method on a set of difficult fluorescein image pairs.

Choe, Tae Eun; Medioni, Gerard; Cohen, Isaac; Walsh, Alexander C.; Sadda, SriniVas R.

2008-01-01

142

Real-time continuous image registration enabling ultraprecise 2-D motion tracking.  

PubMed

In this paper, we present a novel continuous image registration method (CIRM), which yields near-zero bias and has high computational efficiency. It can be realized for real-time position estimation to enable ultraprecise 2-D motion tracking and motion control over a large motion range. As the two variables of the method are continuous in spatial domain, pixel-level image registration is unnecessary, thus the CIRM can continuously track the moving target according to the incoming target image. When applied to a specific target object, measurement resolution of the method is predicted according to the reference image model of the object along with the variance of the camera's overall image noise. The maximum permissible target speed is proportional to the permissible frame rate, which is limited by the required computational time. The precision, measurement resolution, and computational efficiency of the method are verified through computer simulations and experiments. Specifically, the CIRM is implemented and integrated with a visual sensing system. Near-zero bias, measurement resolution of 0.1 nm (0.0008 pixels), and measurement of one nanometer stepping are demonstrated. PMID:23380857

Cheng, Peng; Menq, Chia-Hsiang

2013-05-01

143

Constructing a Database from Multiple 2D Images for Camera Pose Estimation and Robot Localization  

NASA Technical Reports Server (NTRS)

The LMDB (Landmark Database) Builder software identifies persistent image features (landmarks) in a scene viewed multiple times and precisely estimates the landmarks 3D world positions. The software receives as input multiple 2D images of approximately the same scene, along with an initial guess of the camera poses for each image, and a table of features matched pair-wise in each frame. LMDB Builder aggregates landmarks across an arbitrarily large collection of frames with matched features. Range data from stereo vision processing can also be passed to improve the initial guess of the 3D point estimates. The LMDB Builder aggregates feature lists across all frames, manages the process to promote selected features to landmarks, and iteratively calculates the 3D landmark positions using the current camera pose estimations (via an optimal ray projection method), and then improves the camera pose estimates using the 3D landmark positions. Finally, it extracts image patches for each landmark from auto-selected key frames and constructs the landmark database. The landmark database can then be used to estimate future camera poses (and therefore localize a robotic vehicle that may be carrying the cameras) by matching current imagery to landmark database image patches and using the known 3D landmark positions to estimate the current pose.

Wolf, Michael; Ansar, Adnan I.; Brennan, Shane; Clouse, Daniel S.; Padgett, Curtis W.

2012-01-01

144

Temperature-Dependent Conformations of a Membrane Supported 'Zinc Porphyrin Tweezer' by 2D Fluorescence Spectroscopy  

PubMed Central

We studied the equilibrium conformations of a ‘zinc porphyrin tweezer’ composed of two carboxylphenyl-functionalized zinc tetraphenyl porphyrin subunits connected by a 1,4 butyndiol spacer, which was suspended inside the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. By combining phase-modulation two-dimensional fluorescence spectroscopy (2D FS) with linear absorbance and fluorimetry, we determined that the zinc porphyrin tweezer adopts a mixture of ‘folded’ and ‘extended’ conformations in the membrane. By fitting an exciton-coupling model to a series of data sets recorded over a range of temperatures (17 – 85 °C) and at different laser center wavelengths, we determined that the folded form of the tweezer is stabilized by a favorable change in the entropy of the local membrane environment. Our results provide insights toward understanding the balance of thermodynamic factors that govern molecular assembly in membranes.

Widom, Julia R.; Lee, Wonbae; Perdomo-Ortiz, Alejandro; Rappoport, Dmitrij; Molinski, Tadeusz F.; Aspuru-Guzik, Alan; Marcus, Andrew H.

2013-01-01

145

3D interfractional patient position verification using 2D-3D registration of orthogonal images  

SciTech Connect

Reproducible positioning of the patient during fractionated external beam radiation therapy is imperative to ensure that the delivered dose distribution matches the planned one. In this paper, we expand on a 2D-3D image registration method to verify a patient's setup in three dimensions (rotations and translations) using orthogonal portal images and megavoltage digitally reconstructed radiographs (MDRRs) derived from CT data. The accuracy of 2D-3D registration was improved by employing additional image preprocessing steps and a parabolic fit to interpolate the parameter space of the cost function utilized for registration. Using a humanoid phantom, precision for registration of three-dimensional translations was found to be better than 0.5 mm (1 s.d.) for any axis when no rotations were present. Three-dimensional rotations about any axis were registered with a precision of better than 0.2 deg. (1 s.d.) when no translations were present. Combined rotations and translations of up to 4 deg. and 15 mm were registered with 0.4 deg. and 0.7 mm accuracy for each axis. The influence of setup translations on registration of rotations and vice versa was also investigated and mostly agrees with a simple geometric model. Additionally, the dependence of registration accuracy on three cost functions, angular spacing between MDRRs, pixel size, and field-of-view, was examined. Best results were achieved by mutual information using 0.5 deg. angular spacing and a 10x10 cm{sup 2} field-of-view with 140x140 pixels. Approximating patient motion as rigid transformation, the registration method is applied to two treatment plans and the patients' setup errors are determined. Their magnitude was found to be {<=}6.1 mm and {<=}2.7 deg. for any axis in all of the six fractions measured for each treatment plan.

Jans, H.-S.; Syme, A.M.; Rathee, S.; Fallone, B.G. [Department of Medical Physics, Cross Cancer Institute, Departments of Oncology and Physics, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G IZ2 (Canada); Department of Medical Physics, Cross Cancer Institute, Department of Oncology, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G IZ2 (Canada); Department of Medical Physics, Cross Cancer Institute, Departments of Oncology and Physics, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G IZ2 (Canada)

2006-05-15

146

2D Seismic Imaging of Elastic Parameters by Frequency Domain Full Waveform Inversion  

NASA Astrophysics Data System (ADS)

Thanks to recent advances in parallel computing, full waveform inversion is today a tractable seismic imaging method to reconstruct physical parameters of the earth interior at different scales ranging from the near- surface to the deep crust. We present a massively parallel 2D frequency-domain full-waveform algorithm for imaging visco-elastic media from multi-component seismic data. The forward problem (i.e. the resolution of the frequency-domain 2D PSV elastodynamics equations) is based on low-order Discontinuous Galerkin (DG) method (P0 and/or P1 interpolations). Thanks to triangular unstructured meshes, the DG method allows accurate modeling of both body waves and surface waves in case of complex topography for a discretization of 10 to 15 cells per shear wavelength. The frequency-domain DG system is solved efficiently for multiple sources with the parallel direct solver MUMPS. The local inversion procedure (i.e. minimization of residuals between observed and computed data) is based on the adjoint-state method which allows to efficiently compute the gradient of the objective function. Applying the inversion hierarchically from the low frequencies to the higher ones defines a multiresolution imaging strategy which helps convergence towards the global minimum. In place of expensive Newton algorithm, the combined use of the diagonal terms of the approximate Hessian matrix and optimization algorithms based on quasi-Newton methods (Conjugate Gradient, LBFGS, ...) allows to improve the convergence of the iterative inversion. The distribution of forward problem solutions over processors driven by a mesh partitioning performed by METIS allows to apply most of the inversion in parallel. We shall present the main features of the parallel modeling/inversion algorithm, assess its scalability and illustrate its performances with realistic synthetic case studies.

Brossier, R.; Virieux, J.; Operto, S.

2008-12-01

147

Depth Assessment in 2D Planar-Scanning Diffuse Optical Imaging  

NASA Astrophysics Data System (ADS)

Methods for depth assessment in planar-scanning diffuse optical imaging have been recently proposed for the purpose of advancing optical mammography. The typical 2D planar-scanner includes a collinear source-detector pair that scans the breast in the x-y plane and provides a 2D projection image. A second optical detector that is off-axis with respect to the light source has been introduced to determine the depth of a detected object from its spatial shift between the on-axis and off-axis images. The spatial shift of the object was associated to its depth through a theoretical depth-shift curve obtained with diffusion theory. The theoretical depth-shift curve has been shown to be insensitive to variations in sample thickness, background optical properties and inclusion size. In this study, we have experimentally measured depth-shift curves to verify such insensitivity and to confirm the validity of the theoretical predictions under practical experimental conditions that do not match the ideal conditions used to derive the theoretical depth-shift curves. We have experimentally confirmed the insensitivity of the depth-shift curve to sample thickness, inclusion size, and background optical properties for absorption coefficients > 0.09 cm -1. For lower values of the background absorption coefficient, the experimental depth-shift curves deviate from the reported theoretical curves resulting in depth assessment differences of 3-7 mm. We assign this discrepancy to the effect of experimental boundary conditions, which becomes more significant at low absorption values for which the optically probed volume becomes larger. Considering the low absorption coefficient of breast tissue in the near-infrared region (typically ˜0.05 cm-1 ), the results of this thesis indicate that it is appropriate to experimentally derive a depth-shift curve that is specific to the optical mammography system to be used.

Cantor-Balan, Roni

148

Elemental 2D imaging of paintings with a mobile EDXRF system.  

PubMed

Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied. X-ray radiography and infrared reflectography as well as UV photography are some of the most applied techniques. The study of works of art usually requires these techniques to be non-invasive. Furthermore, they are frequently required to perform in situ analysis. A few years ago, our laboratory developed a mobile energy-dispersive X-ray fluorescence and UV-vis-NIR coupled spectrometer, especially designed for fieldwork studies, where all three techniques can be applied strictly at the same site of analysis. Recent developments on a new positioning system have now allowed us to perform 2D elemental mappings with our equipment, which is especially well adapted to painting analysis. The system control is carried out entirely through a laptop computer running a dedicated homemade software. The positioning is achieved by means of a CCD camera embedded in the system and controlled via a Wi-Fi connection through the computer. The data acquisition system, which is made through a homemade multichannel pulse height analyzer, being also managed via the software mentioned above, goes through an Ethernet connection. We will present here the new developments of the system and an example of in situ 2D elemental mapping applied on an anonymous oil painting on wood panel. The discovery of a hidden painting under this oil painting makes it a good choice for a first example of 2D large scan with a mobile instrument. PMID:20953768

Hocquet, François-Philippe; Calvo del Castillo, Helena; Cervera Xicotencatl, Ariadna; Bourgeois, Catherine; Oger, Cécile; Marchal, André; Clar, Mathieu; Rakkaa, Saïd; Micha, Edith; Strivay, David

2011-03-01

149

Temperature dependence of the rate coefficient for charge exchange of metastable O/+//2D/ with N2. [in atmosphere  

NASA Technical Reports Server (NTRS)

Using a data base of aeronomical parameters measured on board the Atmosphere Explorer-C satellite, temperature dependence of the reaction rate coefficient is deduced for the charge exchange of O(+)(2D) with N2. The results indicate the Explorer values determined over the temperature range from 700 to 1900 K are not in conflict with laboratory measurements made at higher temperatures.

Torr, M. R.; Torr, D. G.

1980-01-01

150

Investigation of fast particle driven instabilities by 2D electron cyclotron emission imaging on ASDEX Upgrade  

NASA Astrophysics Data System (ADS)

Detailed measurements of the 2D mode structure of Alfvén instabilities in the current ramp-up phase of neutral beam heated discharges were performed on ASDEX Upgrade, using the electron cyclotron emission imaging (ECEI) diagnostic. This paper focuses on the observation of reversed shear Alfvén eigenmodes (RSAEs) and bursting modes that, with the use of the information from ECEI, have been identified as beta-induced Alfvén eigenmodes (BAEs). Both RSAEs with first and second radial harmonic mode structures were observed. Calculations with the linear gyro-kinetic code LIGKA revealed that the ratio of the damping rates and the frequency difference between the first and second harmonic modes strongly depended on the shape of the q-profile. The bursting character of the BAE type modes, which were radially localized to rational q surfaces, was observed to sensitively depend on the plasma parameters, ranging from strongly bursting to almost steady state.

Classen, I. G. J.; Lauber, Ph; Curran, D.; Boom, J. E.; Tobias, B. J.; Domier, C. W.; Luhmann, N. C., Jr.; Park, H. K.; Garcia Munoz, M.; Geiger, B.; Maraschek, M.; Van Zeeland, M. A.; da Graça, S.; ASDEX Upgrade Team

2011-12-01

151

Experimental comparison of 2D and 3D wavelet image compression methods for medical image sets  

NASA Astrophysics Data System (ADS)

To make the archival and transmission of medical images in PACS (Picture Archiving and Communication Systems) and teleradiology systems user-friendly and economically profitable, the adoption of an efficient compression technique is an important feature in the design of such systems. An important category of lossy compression techniques uses the wavelet transformation for decorrelation of the pixel values, prior to quantization and entropy coding. For the coding of sets of images, the images are mostly independently compressed with a two-dimensional compression scheme. In this way, one discards the similarity between adjacent slices. The aim of this paper is to compare the performance of some two- dimensional and three-dimensional implementations of wavelet compression techniques and investigate some design issues as decomposition depth, the choice of wavelet filters and entropy coding.

van Overloop, Jeroen; van de Sype, Wim; Denecker, Koen N.; de Neve, Peter; Sundermann, Erik; Lemahieu, Ignace

1998-06-01

152

Automatic ultrasound image enhancement for 2D semi-automatic breast-lesion segmentation  

NASA Astrophysics Data System (ADS)

Breast cancer is the fastest growing cancer, accounting for 29%, of new cases in 2012, and second leading cause of cancer death among women in the United States and worldwide. Ultrasound (US) has been used as an indispensable tool for breast cancer detection/diagnosis and treatment. In computer-aided assistance, lesion segmentation is a preliminary but vital step, but the task is quite challenging in US images, due to imaging artifacts that complicate detection and measurement of the suspect lesions. The lesions usually present with poor boundary features and vary significantly in size, shape, and intensity distribution between cases. Automatic methods are highly application dependent while manual tracing methods are extremely time consuming and have a great deal of intra- and inter- observer variability. Semi-automatic approaches are designed to counterbalance the advantage and drawbacks of the automatic and manual methods. However, considerable user interaction might be necessary to ensure reasonable segmentation for a wide range of lesions. This work proposes an automatic enhancement approach to improve the boundary searching ability of the live wire method to reduce necessary user interaction while keeping the segmentation performance. Based on the results of segmentation of 50 2D breast lesions in US images, less user interaction is required to achieve desired accuracy, i.e. < 80%, when auto-enhancement is applied for live-wire segmentation.

Lu, Kongkuo; Hall, Christopher S.

2014-03-01

153

Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media  

NASA Technical Reports Server (NTRS)

A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/<.DELTA.Xj.DELTA.Xj> Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absorption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Gayen, Swapan K. (Inventor)

2000-01-01

154

Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media  

NASA Technical Reports Server (NTRS)

A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: ##EQU1## wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/<.DELTA.Xj.DELTA.Xj> Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absoption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Liu, Feng (Inventor); Lax, Melvin (Inventor); Das, Bidyut B. (Inventor)

1999-01-01

155

Numerical simulation of 2D buoyant jets in ice-covered and temperature-stratified water  

NASA Astrophysics Data System (ADS)

A two-dimensional (2D) unsteady simulation model is applied to the problem of a submerged warm water discharge into a stratified lake or reservoir with an ice cover. Numerical simulations and analyses are conducted to gain insight into large-scale convective recirculation and flow processes in a cold waterbody induced by a buoyant jet. Jet behaviors under various discharge temperatures are captured by directly modeling flow and thermal fields. Flow structures and processes are described by the simulated spatial and temporal distributions of velocity and temperature in various regions: deflection, recirculation, attachment, and impingement. Some peculiar hydrothermal and dynamic features, e.g. reversal of buoyancy due to the dilution of a warm jet by entraining cold ambient water, are identified and examined. Simulation results show that buoyancy is the most important factor controlling jet behavior and mixing processes. The inflow boundary is treated as a liquid wall from which the jet is offset. Similarity and difference in effects of boundaries perpendicular and parallel to flow, and of buoyancy on jet attachment and impingement, are discussed. Symmetric flow configuration is used to de-emphasize the Coanda effect caused by offset.

Gu, Ruochuan

156

2D modelling of electron and ion temperature in the plasma edge and SOL  

NASA Astrophysics Data System (ADS)

We are interested here in modelling the electron and ion temperature fields, Te and Ti respectively, in order to understand the main trends that govern the ratio Ti/Te that is being better documented in the SOL with RFA probes [1,2]. The experimental evidence gathered from several devices indicates that this temperature ratio significantly exceeds unity in most data sets that have been analysed, including measurements in the SOL of limiter devices like Tore Supra. Several issues of interest have been addressed with this version of the SOLEDGE-2D code. First, we have analysed the width of the SOL heat channels to the wall components and compared these values to analytical expressions. The key control mechanism of the width of the SOL heat channel is given by a balance between the sheath boundary conditions and the transverse transport. More advanced simulations address the interplay between the edge and SOL plasma allowing one to recover regimes with Ti/Te > 1.

Isoardi, L.; Bufferand, H.; Chiavassa, G.; Ciraolo, G.; Schwander, F.; Serre, E.; Viazzo, S.; Fedorczak, N.; Ghendrih, Ph.; Gunn, J.; Sarazin, Y.; Tamain, P.

2011-08-01

157

FluoRender: An Application of 2D Image Space Methods for 3D and 4D Confocal Microscopy Data Visualization in Neurobiology Research  

PubMed Central

2D image space methods are processing methods applied after the volumetric data are projected and rendered into the 2D image space, such as 2D filtering, tone mapping and compositing. In the application domain of volume visualization, most 2D image space methods can be carried out more efficiently than their 3D counterparts. Most importantly, 2D image space methods can be used to enhance volume visualization quality when applied together with volume rendering methods. In this paper, we present and discuss the applications of a series of 2D image space methods as enhancements to confocal microscopy visualizations, including 2D tone mapping, 2D compositing, and 2D color mapping. These methods are easily integrated with our existing confocal visualization tool, FluoRender, and the outcome is a full-featured visualization system that meets neurobiologists’ demands for qualitative analysis of confocal microscopy data.

Wan, Yong; Otsuna, Hideo; Chien, Chi-Bin; Hansen, Charles

2013-01-01

158

A new method of diaphragm apex motion detection from 2D projection images of mega-voltage cone beam CT.  

PubMed

To present a new method of estimating 3D positions of the ipsi-lateral hemi-diaphragm apex (IHDA) from 2D projection images of mega-voltage cone beam CT (MVCBCT). The detection framework reconstructs a 3D volume from all the 2D projection images. An initial estimated 3D IHDA position is determined in this volume based on an imaging processing pipeline, including Otsu thresholding, connected component labeling and template matching. This initial position is then projected onto each 2D projection image to create a region of interest (ROI). To accurately detect the IHDA position in 2D projection space, two methods, dynamic Hough transform (DHT) and a tracking approach based on a joint probability density function (PDF) are developed. Both methods utilize a double-parabola model to fit the 2D diaphragm boundary. The 3D IHDA motion in the superior-inferior (SI) direction is estimated from the initial static 3D position and the detected 2D positions in projection space. The two Hough-based detection methods are tested on 35 MVCBCT scans from 15 patients. The detection is compared to manually identified IHDA positions in 2D projection space by three clinicians. An average and standard deviation of 4.252 ± 3.354 and 2.485 ± 1.750 mm was achieved for DHT and tracking-based approaches respectively, compared with the inter-expert variance among three experts of 1.822 ± 1.106 mm. Based on the results of the scans, the PDF tracking-based approach appears more robust than the DHT. The combination of the automatic ROI localization and the tracking-based approach is a quicker and more accurate method of extracting 3D IHDA motion from 2D projection images. PMID:23321998

Chen, Mingqing; Bai, Junjie; Siochi, R Alfredo C

2013-02-01

159

Temperature and layer number dependence of the G and 2D phonon energy and damping in graphene.  

PubMed

We have studied the temperature and size dependence of the G and 2D phonon modes in graphene. It is shown that in a graphene monolayer the phonon energy decreases whereas the phonon damping increases with increasing temperature. The electron-phonon interaction leads to hardening whereas the fourth-order anharmonic phonon-phonon processes lead to softening of the phonon energy with increasing temperature. We have shown that the electron-phonon interaction plays an important role also by the dispersion dependence of the phonon G mode, by the observation of the Kohn anomaly. The G mode frequency decreases and damping increases, whereas the 2D phonon frequency and damping increase with increasing layer number. The temperature and size effects of the 2D mode are much stronger than those of the G mode. PMID:22569003

Apostolov, A T; Apostolova, I N; Wesselinowa, J M

2012-06-13

160

Automatic Segmentation and Ventricular Border Detection of 2D Echocardiographic Images Combining K-Means Clustering and Active Contour Model  

Microsoft Academic Search

Accurate analysis of 2D echocardiographic images is vital for diagnosis and treatment of heart related diseases. For this task, extraction of cardiac borders must be carried out. In particular, automatic quantitative measurements of Left Ventricle (LV), Right Ventricle (RV), Left Atrium (LA), Right Atrium, Valve size, etc. are essential. We believe that automatic processing of these echo images could speed

S. Nandagopalan; B. S. Adiga; C. Dhanalakshmi; N. Deepak

2010-01-01

161

Ultrasound 2D strain estimator based on image registration for ultrasound elastography  

NASA Astrophysics Data System (ADS)

In this paper, we present a new approach to calculate 2D strain through the registration of the pre- and post-compression (deformation) B-mode image sequences based on an intensity-based non-rigid registration algorithm (INRA). Compared with the most commonly used cross-correlation (CC) method, our approach is not constrained to any particular set of directions, and can overcome displacement estimation errors introduced by incoherent motion and variations in the signal under high compression. This INRA method was tested using phantom and in vivo data. The robustness of our approach was demonstrated in the axial direction as well as the lateral direction where the standard CC method frequently fails. In addition, our approach copes well under large compression (over 6%). In the phantom study, we computed the strain image under various compressions and calculated the signal-to-noise (SNR) and contrast-to-noise (CNS) ratios. The SNR and CNS values of the INRA method were much higher than those calculated from the CC-based method. Furthermore, the clinical feasibility of our approach was demonstrated with the in vivo data from patients with arm lymphedema.

Yang, Xiaofeng; Torres, Mylin; Kirkpatrick, Stephanie; Curran, Walter J.; Liu, Tian

2014-03-01

162

Coronary arteries motion modeling on 2D x-ray images  

NASA Astrophysics Data System (ADS)

During interventional procedures, 3D imaging modalities like CT and MRI are not commonly used due to interference with the surgery and radiation exposure concerns. Therefore, real-time information is usually limited and building models of cardiac motion are difficult. In such case, vessel motion modeling based on 2-D angiography images become indispensable. Due to issues with existing vessel segmentation algorithms and the lack of contrast in occluded vessels, manual segmentation of certain branches is usually necessary. In addition, such occluded branches are the most important vessels during coronary interventions and obtaining motion models for these can greatly help in reducing the procedure time and radiation exposure. Segmenting different cardiac phases independently does not guarantee temporal consistency and is not efficient for occluded branches required manual segmentation. In this paper, we propose a coronary motion modeling system which extracts the coronary tree for every cardiac phase, maintaining the segmentation by tracking the coronary tree during the cardiac cycle. It is able to map every frame to the specific cardiac phase, thereby inferring the shape information of the coronary arteries using the model corresponding to its phase. Our experiments show that our motion modeling system can achieve promising results with real-time performance.

Gao, Yang; Sundar, Hari

2012-02-01

163

Comparative study of multi-2D, Full 3D and hybrid strategies for multi\\/hyperspectral image compression  

Microsoft Academic Search

In this paper, we investigate appropriate strategies for multi\\/hyperspectral image compression. In particular, we compare the classic multi-2D compression strategy and two different implementations of 3D strategies (Full 3D and hybrid). All strategies are combined with a PCA decorrelation stage to optimize performance. For multi-2D and hybrid strategies, we propose a weighted version of PCA. Finally, for consistent evaluation, we

Jonathan Delcourt; Alamin Mansouri; Tadeusz Sliwa; Yvon Voisin

2009-01-01

164

2-D simulation and analysis of temperature effects on electrical parameters degradation of power RF LDMOS device  

Microsoft Academic Search

This paper presents a synthesis of temperature effects on power RF Laterally Diffused (LD) MOS performances, which can modify and degrade transistor physical and electrical behaviour. In this work, the temperature influence on device electrical characteristics is discussed with regard to physical limits for device operation. A developed 2-D structure was implemented and simulated using the physical simulator Silvaco-Atlas to

M. A. Belaïd; K. Ketata; M. Gares; J. Marcon; K. Mourgues; M. Masmoudi

2006-01-01

165

Analysis of 2-d ultrasound cardiac strain imaging using joint probability density functions.  

PubMed

Ultrasound frame rates play a key role for accurate cardiac deformation tracking. Insufficient frame rates lead to an increase in signal de-correlation artifacts resulting in erroneous displacement and strain estimation. Joint probability density distributions generated from estimated axial strain and its associated signal-to-noise ratio provide a useful approach to assess the minimum frame rate requirements. Previous reports have demonstrated that bi-modal distributions in the joint probability density indicate inaccurate strain estimation over a cardiac cycle. In this study, we utilize similar analysis to evaluate a 2-D multi-level displacement tracking and strain estimation algorithm for cardiac strain imaging. The effect of different frame rates, final kernel dimensions and a comparison of radio frequency and envelope based processing are evaluated using echo signals derived from a 3-D finite element cardiac model and five healthy volunteers. Cardiac simulation model analysis demonstrates that the minimum frame rates required to obtain accurate joint probability distributions for the signal-to-noise ratio and strain, for a final kernel dimension of 1 ? by 3 A-lines, was around 42 Hz for radio frequency signals. On the other hand, even a frame rate of 250 Hz with envelope signals did not replicate the ideal joint probability distribution. For the volunteer study, clinical data was acquired only at a 34 Hz frame rate, which appears to be sufficient for radio frequency analysis. We also show that an increase in the final kernel dimensions significantly affect the strain probability distribution and joint probability density function generated, with a smaller effect on the variation in the accumulated mean strain estimated over a cardiac cycle. Our results demonstrate that radio frequency frame rates currently achievable on clinical cardiac ultrasound systems are sufficient for accurate analysis of the strain probability distribution, when a multi-level 2-D algorithm and kernel dimensions on the order of 1 ? by 3 A-lines or smaller are utilized. PMID:24613642

Ma, Chi; Varghese, Tomy

2014-06-01

166

Dynamic tracking of a deformable tissue based on 3D-2D MR-US image registration  

NASA Astrophysics Data System (ADS)

Real-time registration of pre-operative magnetic resonance (MR) or computed tomography (CT) images with intra-operative Ultrasound (US) images can be a valuable tool in image-guided therapies and interventions. This paper presents an automatic method for dynamically tracking the deformation of a soft tissue based on registering pre-operative three-dimensional (3D) MR images to intra-operative two-dimensional (2D) US images. The registration algorithm is based on concepts in state estimation where a dynamic finite element (FE)- based linear elastic deformation model correlates the imaging data in the spatial and temporal domains. A Kalman-like filtering process estimates the unknown deformation states of the soft tissue using the deformation model and a measure of error between the predicted and the observed intra-operative imaging data. The error is computed based on an intensity-based distance metric, namely, modality independent neighborhood descriptor (MIND), and no segmentation or feature extraction from images is required. The performance of the proposed method is evaluated by dynamically deforming 3D pre-operative MR images of a breast phantom tissue based on real-time 2D images obtained from an US probe. Experimental results on different registration scenarios showed that deformation tracking converges in a few iterations. The average target registration error on the plane of 2D US images for manually selected fiducial points was between 0.3 and 1.5 mm depending on the size of deformation.

Marami, Bahram; Sirouspour, Shahin; Fenster, Aaron; Capson, David W.

2014-03-01

167

Stochastic rank correlation: a robust merit function for 2D/3D registration of image data obtained at different energies.  

PubMed

In this article, the authors evaluate a merit function for 2D/3D registration called stochastic rank correlation (SRC). SRC is characterized by the fact that differences in image intensity do not influence the registration result; it therefore combines the numerical advantages of cross correlation (CC)-type merit functions with the flexibility of mutual-information-type merit functions. The basic idea is that registration is achieved on a random subset of the image, which allows for an efficient computation of Spearman's rank correlation coefficient. This measure is, by nature, invariant to monotonic intensity transforms in the images under comparison, which renders it an ideal solution for intramodal images acquired at different energy levels as encountered in intrafractional kV imaging in image-guided radiotherapy. Initial evaluation was undertaken using a 2D/3D registration reference image dataset of a cadaver spine. Even with no radiometric calibration, SRC shows a significant improvement in robustness and stability compared to CC. Pattern intensity, another merit function that was evaluated for comparison, gave rather poor results due to its limited convergence range. The time required for SRC with 5% image content compares well to the other merit functions; increasing the image content does not significantly influence the algorithm accuracy. The authors conclude that SRC is a promising measure for 2D/3D registration in IGRT and image-guided therapy in general. PMID:19746775

Birkfellner, Wolfgang; Stock, Markus; Figl, Michael; Gendrin, Christelle; Hummel, Johann; Dong, Shuo; Kettenbach, Joachim; Georg, Dietmar; Bergmann, Helmar

2009-08-01

168

Fast Ion Induced Shearing of 2D Alfven Eigenmodes Measured by Electron Cyclotron Emission Imaging  

SciTech Connect

Two-dimensional images of electron temperature perturbations are obtained with electron cyclotron emission imaging (ECEI) on the DIII-D tokamak and compared to Alfven eigenmode structures obtained by numerical modeling using both ideal MHD and hybrid MHD-gyrofluid codes. While many features of the observations are found to be in excellent agreement with simulations using an ideal MHD code (NOVA), other characteristics distinctly reveal the influence of fast ions on the mode structures. These features are found to be well described by the nonperturbative hybrid MHD-gyrofluid model TAEFL.

Tobias, Ben [University of California, Davis; Classen, I.G.J. [FOM Institute for Plasma Physics Rijnhuizen, Nieuwegein, The Netherlands; Domier, C. W. [University of California, Davis; Heidbrink, W. [University of California, Irvine; Luhmann, N.C. [University of California, Davis; Nazikian, Raffi [Princeton Plasma Physics Laboratory (PPPL); Park, H.K. [Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea; Spong, Donald A [ORNL; Van Zeeland, Michael [General Atomics

2011-01-01

169

Measuring significant inhomogeneity and anisotropy in indoor convective air turbulence in the presence of 2D temperature gradient  

NASA Astrophysics Data System (ADS)

Using a novel set up, experimental study of the statistical properties of a light beam propagating horizontally through indoor convective air turbulence in the presence of a 2D temperature gradient (TG) is presented. A laser beam enters a telescope from its back focal point by virtue of an optical fiber and is expanded and recollimated by it and then passes through the turbulent area. Then the beam enters another telescope’s aperture. A mask consisting of four similar widely separated small subapertures was installed in front of the second telescope’s aperture. The subapertures were equidistant from the optical axis of the telescope and located at the corners of a square. A flat plane heater is used to produce a vertical TG in the medium. Due to the limited width of the heater, a horizontal component for the TG appeared. Near the focal plane of the second telescope, four distinct images of the source are formed and recorded by a CCD camera. Due to the turbulence all the images (spots) in the successive frames fluctuate. Using the four spot displacements we have calculated the fluctuations of the angle of arrival (AA) over the subapertures. The statistical properties of the optical turbulence are investigated using variance analysis of the AA component fluctuations at horizontal and vertical directions over the subapertures for different temperatures of the heater at different heights of the beam path from the heater. Experimental results show that when the heater is turned off, the variances of horizontal and vertical components of the AA fluctuations are approximately equal to zero over all the subapertures. When it is turned on, the variance of the horizontal component of the AA fluctuations over all of the subapertures are larger than those from the vertical one. In addition, in this case, we find a significant dependence of the variance of the AA components on the height from the heater.

Mohammady Razi, E.; Rasouli, Saifollah

2014-04-01

170

Robust lumen segmentation of coronary arteries in 2D angiographic images  

NASA Astrophysics Data System (ADS)

Diagnosis and treatment of coronary diseases depends on the data acquired during angiographic investigations. To provide better assistance for angiographic procedures, a segmentation of the lumen is required. A new algorithm for vessel centerline computation and lumen segmentation in 2D projection coronary angiograms is presented. Centerlines are extracted by a graph-based optimization technique, which searches for paths with minimal costs. The search starts from a source point, which is automatically set by the proposed algorithm. A new objective function for determining the costs of the graph edges is proposed. It consists of the response from the medialness filter and is regularized by the centerline potential function. In the medialness filter a vessel cross-section is represented by a 1D profile parameterized by center position and radius. The medialness filter at a point optimizes a gradient-based response over the profile radius. The proposed centerline potential function defines likeliness of each point of the image to be a centerline. Both the medialness filter and the centerline potential function are multi-scale. The entire lumen segmentation is achieved by the radii extracted during the medialness response computation. Application to clinical data shows that the presented algorithm segments coronary lumen with good accuracy and allows for subsequent assessment of the quantitative characteristics (i.e. diameter, curvature, etc.) of the vessels.

Polyanskaya, Maria; Schwemmer, Chris; Linarth, Andre; Lauritsch, Guenter; Hornegger, Joachim

2012-02-01

171

Detection of Cracks Using 2d Electrical Resistivity Imaging In A Cultivated Soil  

NASA Astrophysics Data System (ADS)

Variations of soil structure is significant for the understanding of water and gas trans- fer in soil profiles. In the context of arable land, soil structure can be compacted due to either agriculture operation (wheel tracks), or hardsetting and crusting processes. As a consequence, soil porosity is reduced which may lead to decrease water infiltra- tion and to anoxic conditions. Porosity can be increased by cracks formation due to swelling and shrinking phenomenon. We present here a laboratory experiment based on soil electrical characteristics. Electrical resistivity allows a non destructive three di- mensional and dynamical analysis of the soil structure. Our main objective is to detect cracks in the soil. Cracks form an electrical resistant object and the contrast of resis- tivity between air and soil is large enough to be detected. Our sample is an undisturbed soil block 240mm*170mm*160mm with an initial structure compacted by wheel traf- fic. Successive artificial cracks are generated. Electrodes built with 2 mm ceramic cups permit a good electrical contact at the soil surface whatever its water content. They are installed 15 mm apart and the electrical resistivity is monitored using a dipole-dipole and wenner multi-electrodes 2D imaging method which gives a picture of the subsur- face resistivity. The interpreted resistivity sections show the major soil structure. The electrical response changes with the cracks formation. The structure information ex- tracted from the electrical map are in good agreement with the artificially man-made cracks. These first results demonstrate the relevance of high resolution electrical imag- ing of the soil profile. Further experiments need to be carried out in order to monitor natural soil structure evolution during wetting-drying cycles.

Samouëlian, A.; Cousin, I.; Richard, G.; Bruand, A.

172

Enhancing the performance of lateral shear strain estimation by using 2-D strain imaging.  

PubMed

Radio-frequency (RF) ultrasound can be used to estimate deformation of biological tissue. Decorrelation of sequentially acquired ultrasound signals resulting from the deformation imposes a limitation on the precision (elastographic signal-to-noise ratio; SNRe) of estimating these deformations; this is presented as the lateral shear strain filter. In this paper, we explore the effect of a 2-D-window-based strain estimation approach on the lateral shear strain filter and propose an extension of the 1-D theoretical lateral shear strain filter to 2-D. We compared the performance of the 2-D approach in simulated ultrasound data and a tissue-mimicking phantom with that of the 2-D lateral shear strain filter. In simulations, the 2-D-window-based approach shows an effect in the axial direction similar to the 2-D prediction. In simulations and experiments, increasing the window size in the lateral direction shows an increase in the maximum SNRe of the lateral shear strain filter. Increasing the lateral overlap has no effect on the estimation of lateral shear strain. These results were confirmed in the tissue-mimicking phantom experiments. When compared with the 2-D lateral shear strain filter, the results obtained with the 2-D-window-based approach showed an enhanced performance by incorporating the lateral window size in the lateral shear strain estimation, which was consistent with the proposed theory. PMID:24802946

Idzenga, Tim; Hansen, Hendrik H G; Thijssen, Johan M; de Korte, Chris L

2014-05-01

173

Application of 2D and 3D Digital Image Correlation on CO2-like altered carbonate  

NASA Astrophysics Data System (ADS)

In order to provide mechanical constitutive laws for reservoir monitoring during CO2 long term storage, we studied the mechanical properties of Lavoux limestone before and after a homogeneous alteration following the protocol of acid treatments defined by Egermann et al, (2006). The mechanical data have been analysed at the light of systematic microstructural investigations. Firstly, the alteration impact on the evolution of flow properties related to microstructural changes was studied at successive levels of alteration by classical petrophysical measurements of porosity and permeability (including NMR, mercury porosimetry and laser diffraction) and by observations of microstructures on thin sections and by SEM. Secondly, the mechanical properties of the samples were investigated by classical (macroscopic) triaxial and uniaxial tests and are discussed in terms of the structural modifications. The macroscopic tests indicate that the alteration weakens the material, according to the observed decrease of elastic moduli and Uniaxial Compressive Strengths, from 29MPa to 19MPa after 6 cycles of acid treatments. The study is further complemented by 2D full (mechanical) field measurements, thanks to Digital Image Correlation (DIC) performed on images acquired during the uniaxial tests. This technique allows for continuous quantitative micro-mechanical monitoring in terms of deformation history and localisation processes during compression. This technique was applied on both intact and altered materials and at different scales of observation: (i) cm-sized samples were compressed in a classical load frame and optically imaged, (ii) mm-sized samples were loaded with a miniaturized compression rig implemented within a Scanning Electron Microscope. At last, 3D full field measurements were performed by 3D-DIC on mm-sized samples, which were compressed "in-situ" an X-ray microtomograph thanks to a miniaturized triaxial cell allowing for confining pressures of up to 15 MPa. At the macroscale and for the intact samples, a diffuse accommodation of the deformation is observed during the pseudo elastic regime, followed by sudden failure propagation after the peak stress. Conversely, the altered samples exhibit much more localized and pronounced deformation levels. At the SEM scale for the intact samples, but closure of the porosity, failure precursors and localized deformation were not observed. In opposition, the altered samples showed early opening of microcracks at the grain junctions. Finally, at the µ-tomograph resolution (5µm/voxel) and in triaxial conditions, we observed for intact samples at macro and micro scales similar behaviour as for optical and SEM characterization. At 5 MPa of confining pressure the altered samples avoid brittle failure and a few shear bands are visible. As previously inferred from 2D-DIC, we observed strong and early localization of deformation, but the limited resolution of the µ-tomograph did not allow to clearly evidence microcracks. The DIC results suggest that besides the overall increase of porosity, the dissolution processes enhance the local heterogeneities of the porous network, which phenomenon further increases the weakening of the materials.

zinsmeister, Louis; Dautriat, Jérémie; Dimanov, Alexandre; Raphanel, Jean; Bornert, Michel

2013-04-01

174

Registration of 2D x-ray images to 3D MRI by generating pseudo-CT data  

NASA Astrophysics Data System (ADS)

Spatial and soft tissue information provided by magnetic resonance imaging can be very valuable during image-guided procedures, where usually only real-time two-dimensional (2D) x-ray images are available. Registration of 2D x-ray images to three-dimensional (3D) magnetic resonance imaging (MRI) data, acquired prior to the procedure, can provide optimal information to guide the procedure. However, registering x-ray images to MRI data is not a trivial task because of their fundamental difference in tissue contrast. This paper presents a technique that generates pseudo-computed tomography (CT) data from multi-spectral MRI acquisitions which is sufficiently similar to real CT data to enable registration of x-ray to MRI with comparable accuracy as registration of x-ray to CT. The method is based on a k-nearest-neighbors (kNN)-regression strategy which labels voxels of MRI data with CT Hounsfield Units. The regression method uses multi-spectral MRI intensities and intensity gradients as features to discriminate between various tissue types. The efficacy of using pseudo-CT data for registration of x-ray to MRI was tested on ex vivo animal data. 2D-3D registration experiments using CT and pseudo-CT data of multiple subjects were performed with a commonly used 2D-3D registration algorithm. On average, the median target registration error for registration of two x-ray images to MRI data was approximately 1 mm larger than for x-ray to CT registration. The authors have shown that pseudo-CT data generated from multi-spectral MRI facilitate registration of MRI to x-ray images. From the experiments it could be concluded that the accuracy achieved was comparable to that of registering x-ray images to CT data.

van der Bom, M. J.; Pluim, J. P. W.; Gounis, M. J.; van de Kraats, E. B.; Sprinkhuizen, S. M.; Timmer, J.; Homan, R.; Bartels, L. W.

2011-02-01

175

2D/4D marker-free tumor tracking using 4D CBCT as the reference image.  

PubMed

Tumor motion caused by respiration is an important issue in image-guided radiotherapy. A 2D/4D matching method between 4D volumes derived from cone beam computed tomography (CBCT) and 2D fluoroscopic images was implemented to track the tumor motion without the use of implanted markers. In this method, firstly, 3DCBCT and phase-rebinned 4DCBCT are reconstructed from cone beam acquisition. Secondly, 4DCBCT volumes and a streak-free 3DCBCT volume are combined to improve the image quality of the digitally reconstructed radiographs (DRRs). Finally, the 2D/4D matching problem is converted into a 2D/2D matching between incoming projections and DRR images from each phase of the 4DCBCT. The diaphragm is used as a target surrogate for matching instead of using the tumor position directly. This relies on the assumption that if a patient has the same breathing phase and diaphragm position as the reference 4DCBCT, then the tumor position is the same. From the matching results, the phase information, diaphragm position and tumor position at the time of each incoming projection acquisition can be derived. The accuracy of this method was verified using 16 candidate datasets, representing lung and liver applications and one-minute and two-minute acquisitions. The criteria for the eligibility of datasets were described: 11 eligible datasets were selected to verify the accuracy of diaphragm tracking, and one eligible dataset was chosen to verify the accuracy of tumor tracking. The diaphragm matching accuracy was 1.88 ± 1.35 mm in the isocenter plane and the 2D tumor tracking accuracy was 2.13 ± 1.26 mm in the isocenter plane. These features make this method feasible for real-time marker-free tumor motion tracking purposes. PMID:24710793

Wang, Mengjiao; Sharp, Gregory C; Rit, Simon; Delmon, Vivien; Wang, Guangzhi

2014-05-01

176

2D/4D marker-free tumor tracking using 4D CBCT as the reference image  

NASA Astrophysics Data System (ADS)

Tumor motion caused by respiration is an important issue in image-guided radiotherapy. A 2D/4D matching method between 4D volumes derived from cone beam computed tomography (CBCT) and 2D fluoroscopic images was implemented to track the tumor motion without the use of implanted markers. In this method, firstly, 3DCBCT and phase-rebinned 4DCBCT are reconstructed from cone beam acquisition. Secondly, 4DCBCT volumes and a streak-free 3DCBCT volume are combined to improve the image quality of the digitally reconstructed radiographs (DRRs). Finally, the 2D/4D matching problem is converted into a 2D/2D matching between incoming projections and DRR images from each phase of the 4DCBCT. The diaphragm is used as a target surrogate for matching instead of using the tumor position directly. This relies on the assumption that if a patient has the same breathing phase and diaphragm position as the reference 4DCBCT, then the tumor position is the same. From the matching results, the phase information, diaphragm position and tumor position at the time of each incoming projection acquisition can be derived. The accuracy of this method was verified using 16 candidate datasets, representing lung and liver applications and one-minute and two-minute acquisitions. The criteria for the eligibility of datasets were described: 11 eligible datasets were selected to verify the accuracy of diaphragm tracking, and one eligible dataset was chosen to verify the accuracy of tumor tracking. The diaphragm matching accuracy was 1.88 ± 1.35 mm in the isocenter plane and the 2D tumor tracking accuracy was 2.13 ± 1.26 mm in the isocenter plane. These features make this method feasible for real-time marker-free tumor motion tracking purposes.

Wang, Mengjiao; Sharp, Gregory C.; Rit, Simon; Delmon, Vivien; Wang, Guangzhi

2014-05-01

177

Characterization of polyolefins by comprehensive high-temperature two-dimensional liquid chromatography (HT 2D-LC)  

Microsoft Academic Search

Temperature rising elution fractionation hyphenated to size exclusion chromatography (TREF×SEC) is a routine technique to determine the chemical heterogeneity of semicrystalline olefin copolymers. A serious limitation is its applicability to non crystallizing samples. Comprehensive high temperature two-dimensional liquid chromatography (HT 2D-LC) gives an alternative to characterize the chemical heterogeneity of copolymers irrespective of their crystallizability. We have hyphenated interactive HPLC,

Anton Ginzburg; Tibor Macko; Volker Dolle; Robert Brüll

2011-01-01

178

Viewing effects of 3-D images synthesized from a series of 2-D tomograms by VAP and HAP approaches  

NASA Astrophysics Data System (ADS)

We report, for the first time, the experimental result and its analysis of synthesizing a series of simulating 2-D tomograms into a 3-D monochromatic image. Our result shows clearly the advantage in monochromaticity of a vertical area-partition (VAP) approach over a horizontal area-partition (HAP) approach during the final white-light reconstruction. This monochromaticity will ensure a 3-D image synthesis without any distortion in gray level or positional recovery.

Zhai, H. C.; Wang, M. W.; Liu, F. M.; Hsu, Ken Y.

179

Measurements of Thermal Conductivity of Superfluid Helium Near its Transition Temperature T(sub lambda) in a 2D Confinement  

NASA Technical Reports Server (NTRS)

We report our recent experiments on thermal conductivity measurements of superfluid He-4 near its phase transition in a two-dimensional (2D) confinement under saturated vapor pressure. A 2D confinement is created by 2-mm- and 1-mm-thick glass capillary plates, consisting of densely populated parallel microchannels with cross-sections of 5 x 50 and 1 x 10 microns, correspondingly. A heat current (2 < Q < 400 nW/sq cm) was applied along the channels long direction. High-resolution measurements were provided by DC SQUID-based high-resolution paramagnetic salt thermometers (HRTs) with a nanokelvin resolution. We might find that thermal conductivity of confined helium is finite at the bulk superfluid transition temperature. Our 2D results will be compared with those in a bulk and 1D confinement.

Jerebets, Sergei

2004-01-01

180

Cerebral microbleeds: accelerated 3D T2*-weighted GRE MR imaging versus conventional 2D T2*-weighted GRE MR imaging for detection.  

PubMed

The purpose of this study was to prospectively compare high-spatial-resolution accelerated three-dimensional (3D) T2*-weighted gradient-recalled-echo (GRE) magnetic resonance (MR) images with conventional two-dimensional (2D) T2*-weighted GRE MR images for the depiction of cerebral microbleeds. After obtaining institutional review board approval and informed consent, 200 elderly participants (age range, 69.7-96.7 years; 108 [54%] women) were imaged at 1.5 T by using both sequences. Presence, number, and location of microbleeds were recorded for both sequences, and differences were tested by using McNemar and signed rank tests. Cerebral microbleeds were detected in significantly more participants on 3D T2*-weighted GRE images (35.5%) than on 2D T2*-weighted GRE images (21.0%; P < .001). Furthermore, in persons with microbleeds visualized on both image sets, significantly more microbleeds (P < .001) were seen on 3D images than on 2D images. For both sequences, the proportion of participants with a microbleed in a lobar (cortical gray and subcortical white matter), deep, or infratentorial location was similar. In conclusion, accelerated 3D T2*-weighted GRE images depict more microbleeds than do conventional 2D T2*-weighted GRE images. PMID:18490493

Vernooij, Meike W; Ikram, M Arfan; Wielopolski, Piotr A; Krestin, Gabriel P; Breteler, Monique M B; van der Lugt, Aad

2008-07-01

181

Development and validation of a modelling framework for simulating 2D-mammography and breast tomosynthesis images.  

PubMed

Planar 2D x-ray mammography is generally accepted as the preferred screening technique used for breast cancer detection. Recently, digital breast tomosynthesis (DBT) has been introduced to overcome some of the inherent limitations of conventional planar imaging, and future technological enhancements are expected to result in the introduction of further innovative modalities. However, it is crucial to understand the impact of any new imaging technology or methodology on cancer detection rates and patient recall. Any such assessment conventionally requires large scale clinical trials demanding significant investment in time and resources. The concept of virtual clinical trials and virtual performance assessment may offer a viable alternative to this approach. However, virtual approaches require a collection of specialized modelling tools which can be used to emulate the image acquisition process and simulate images of a quality indistinguishable from their real clinical counterparts. In this paper, we present two image simulation chains constructed using modelling tools that can be used for the evaluation of 2D-mammography and DBT systems. We validate both approaches by comparing simulated images with real images acquired using the system being simulated. A comparison of the contrast-to-noise ratios and image blurring for real and simulated images of test objects shows good agreement ( < 9% error). This suggests that our simulation approach is a promising alternative to conventional physical performance assessment followed by large scale clinical trials. PMID:25029333

Elangovan, Premkumar; Warren, Lucy M; Mackenzie, Alistair; Rashidnasab, Alaleh; Diaz, Oliver; Dance, David R; Young, Kenneth C; Bosmans, Hilde; Strudley, Celia J; Wells, Kevin

2014-08-01

182

Robustness and accuracy of feature-based single image 2-D-3-D registration without correspondences for image-guided intervention.  

PubMed

2-D-to-3-D registration is critical and fundamental in image-guided interventions. It could be achieved from single image using paired point correspondences between the object and the image. The common assumption that such correspondences can readily be established does not necessarily hold for image guided interventions. Intraoperative image clutter and an imperfect feature extraction method may introduce false detection and, due to the physics of X-ray imaging, the 2-D image point features may be indistinguishable from each other and/or obscured by anatomy causing false detection of the point features. These create difficulties in establishing correspondences between image features and 3-D data points. In this paper, we propose an accurate, robust, and fast method to accomplish 2-D-3-D registration using a single image without the need for establishing paired correspondences in the presence of false detection. We formulate 2-D-3-D registration as a maximum likelihood estimation problem, which is then solved by coupling expectation maximization with particle swarm optimization. The proposed method was evaluated in a phantom and a cadaver study. In the phantom study, it achieved subdegree rotation errors and submillimeter in-plane ( X- Y plane) translation errors. In both studies, it outperformed the state-of-the-art methods that do not use paired correspondences and achieved the same accuracy as a state-of-the-art global optimal method that uses correct paired correspondences. PMID:23955696

Xin Kang; Armand, Mehran; Otake, Yoshito; Wai-Pan Yau; Cheung, Paul Y S; Yong Hu; Taylor, Russell H

2014-01-01

183

Assessment of some problematic factors in facial image identification using a 2D/3D superimposition technique.  

PubMed

The number of criminal cases requiring facial image identification of a suspect has been increasing because a surveillance camera is installed everywhere in the city and furthermore, the intercom with the recording function is installed in the home. In this study, we aimed to analyze the usefulness of a 2D/3D facial image superimposition system for image identification when facial aging, facial expression, and twins are under consideration. As a result, the mean values of the average distances calculated from the 16 anatomical landmarks between the 3D facial images of the 50s groups and the 2D facial images of the 20s, 30s, and 40s groups were 2.6, 2.3, and 2.2mm, respectively (facial aging). The mean values of the average distances calculated from 12 anatomical landmarks between the 3D normal facial images and four emotional expressions were 4.9 (laughter), 2.9 (anger), 2.9 (sadness), and 3.6mm (surprised), respectively (facial expressions). The average distance obtained from 11 anatomical landmarks between the same person in twins was 1.1mm, while the average distance between different person in twins was 2.0mm (twins). Facial image identification using the 2D/3D facial image superimposition system demonstrated adequate statistical power and identified an individual with high accuracy, suggesting its usefulness. However, computer technology concerning video image processing and superimpose progress, there is a need to keep familiar with the morphology and anatomy as its base. PMID:23886899

Atsuchi, Masaru; Tsuji, Akiko; Usumoto, Yosuke; Yoshino, Mineo; Ikeda, Noriaki

2013-09-01

184

Parallel computation of optimized arrays for 2-D electrical imaging surveys  

NASA Astrophysics Data System (ADS)

Modern automatic multi-electrode survey instruments have made it possible to use non-traditional arrays to maximize the subsurface resolution from electrical imaging surveys. Previous studies have shown that one of the best methods for generating optimized arrays is to select the set of array configurations that maximizes the model resolution for a homogeneous earth model. The Sherman-Morrison Rank-1 update is used to calculate the change in the model resolution when a new array is added to a selected set of array configurations. This method had the disadvantage that it required several hours of computer time even for short 2-D survey lines. The algorithm was modified to calculate the change in the model resolution rather than the entire resolution matrix. This reduces the computer time and memory required as well as the computational round-off errors. The matrix-vector multiplications for a single add-on array were replaced with matrix-matrix multiplications for 28 add-on arrays to further reduce the computer time. The temporary variables were stored in the double-precision Single Instruction Multiple Data (SIMD) registers within the CPU to minimize computer memory access. A further reduction in the computer time is achieved by using the computer graphics card Graphics Processor Unit (GPU) as a highly parallel mathematical coprocessor. This makes it possible to carry out the calculations for 512 add-on arrays in parallel using the GPU. The changes reduce the computer time by more than two orders of magnitude. The algorithm used to generate an optimized data set adds a specified number of new array configurations after each iteration to the existing set. The resolution of the optimized data set can be increased by adding a smaller number of new array configurations after each iteration. Although this increases the computer time required to generate an optimized data set with the same number of data points, the new fast numerical routines has made this practical on commonly available microcomputers.

Loke, M. H.; Wilkinson, P. B.; Chambers, J. E.

2010-12-01

185

Automated 2D-3D registration of portal images and CT data using line-segment enhancement  

PubMed Central

In prostate radiotherapy, setup errors with respect to the patient’s bony anatomy can be reduced by aligning 2D megavoltage (MV) portal images acquired during treatment to a reference 3D kilovoltage (kV) CT acquired for treatment planning purposes. The purpose of this study was to evaluate a fully automated 2D–3D registration algorithm to quantify setup errors in 3D through the alignment of line-enhanced portal images and digitally reconstructed radiographs computed from the CT. The line-enhanced images were obtained by correlating the images with a filter bank of short line segments, or “sticks” at different orientations. The proposed methods were validated on (1) accurately collected gold-standard data consisting of a 3D kV cone-beam CT scan of an anthropomorphic phantom of the pelvis and 2D MV portal images in the anterior–posterior (AP) view acquired at 15 different poses and (2) a conventional 3D kV CT scan and weekly 2D MV AP portal images of a patient over 8weeks. The mean (and standard deviation) of the absolute registration error for rotations around the right-lateral (RL), inferior–superior (IS), and posterior–anterior (PA) axes were 0.212° (0.214°), 0.055° (0.033°) and 0.041° (0.039°), respectively. The corresponding registration errors for translations along the RL, IS, and PA axes were 0.161(0.131)mm, 0.096(0.033)mm, and 0.612(0.485)mm. The mean (and standard deviation) of the total registration error was 0.778(0.543)mm. Registration on the patient images was successful in all eight cases as determined visually. The results indicate that it is feasible to automatically enhance features in MV portal images of the pelvis for use within a completely automated 2D–3D registration framework for the accurate determination of patient setup errors. They also indicate that it is feasible to estimate all six transformation parameters from a 3D CT of the pelvis and a single portal image in the AP view.

Munbodh, Reshma; Chen, Zhe; Jaffray, David A.; Moseley, Douglas J.; Knisely, Jonathan P.S.; Duncan, James S.

2008-01-01

186

First Ion Temperature Images From TWINS Data  

NASA Astrophysics Data System (ADS)

Ion heating has been correlated with several magnetospheric phenomena, including magnetic reconnection, instabilities, and convection of plasma through different regions of the magnetosphere. Thus, it important to be able to measure ion temperatures throughout the magnetosphere to better understand the physics of these phenomena. Effective ion temperatures based on the charge-exchange cross section-corrected energetic neutral atom (ENA) flux versus energy spectrum can be calculated from TWINS data. Effective ion temperatures calculated from the Medium Energy Neutral Atom (MENA) imager on the IMAGE spacecraft using this technique were shown to have excellent (within ~30%) agreement with in-situ measurements from MPA instruments on LANL geosynchronous spacecraft and GEOTAIL. In order to achieve adequate statistics for reliable ion temperature calculations, we can use either data with significant ENA flux rates, such as during geomagnetic storms, or superpositions of multiple data sets. We present ion temperature images from the few small storms that have occurred so far in the TWINS mission. We will present both 'skymap' images as well as 2-D maps created using an algorithm to project the data along each pixel's line-of-sight to the equatorial plane of the Geocentric Solar Magnetospheric (GSM) coordinate system. During intervals for which data is available from both TWINS I and II, we will compare the locations of interesting features as seen by the two satellites.

Keesee, A. M.; Scime, E.

2009-05-01

187

Towards real-time 2D/3D registration for organ motion monitoring in image-guided radiation therapy  

NASA Astrophysics Data System (ADS)

Nowadays, radiation therapy systems incorporate kV imaging units which allow for the real-time acquisition of intra-fractional X-ray images of the patient with high details and contrast. An application of this technology is tumor motion monitoring during irradiation. For tumor tracking, implanted markers or position sensors are used which requires an intervention. 2D/3D intensity based registration is an alternative, non-invasive method but the procedure must be accelerate to the update rate of the device, which lies in the range of 5 Hz. In this paper we investigate fast CT to a single kV X-ray 2D/3D image registration using a new porcine reference phantom with seven implanted fiducial markers. Several parameters influencing the speed and accuracy of the registrations are investigated. First, four intensity based merit functions, namely Cross-Correlation, Rank Correlation, Mutual Information and Correlation Ratio, are compared. Secondly, wobbled splatting and ray casting rendering techniques are implemented on the GPU and the influence of each algorithm on the performance of 2D/3D registration is evaluated. Rendering times for a single DRR of 20 ms were achieved. Different thresholds of the CT volume were also examined for rendering to find the setting that achieves the best possible correspondence with the X-ray images. Fast registrations below 4 s became possible with an inplane accuracy down to 0.8 mm.

Gendrin, C.; Spoerk, J.; Bloch, C.; Pawiro, S. A.; Weber, C.; Figl, M.; Markelj, P.; Pernus, F.; Georg, D.; Bergmann, H.; Birkfellner, W.

2010-03-01

188

Evaluation of an efficient GPU implementation of digitally reconstructed radiographs in 3D/2D image registration  

NASA Astrophysics Data System (ADS)

Intensity-based three-dimensional to two-dimensional (3D/2D) X-ray image registration algorithms usually require generating digitally reconstructed radiographs (DRRs) in every iteration during their optimization phase. Thus a large part of the computation time of such registration algorithms is spent in computing these DRRs. In a 3D-to-multiple-2D image registration framework where a sequence of DRRs is calculated, not only the computation but also the memory cost is high. We present an efficient DRR generation method to reduce both costs on a graphical processing units (GPU) implementation. The method relies on integrating a precomputation stage and a narrow-band region-of-interest calculation into the DRR generation. We have demonstrated its benefits on a previously proposed non-rigid 4D-to-multiple-2D image registration framework to estimate cerebral aneurysm wall motion. The two tested algorithms initially required several hours of highly intensive computation that involves generating a large number of DRRs in every iteration. In this paper, results on datasets of digital and physical pulsating cerebral aneurysm phantoms showed a speedup factor of around 50x in the generation of DRRs. In further image registration based wall motion estimation experiments using our implementation, we could obtain estimation results through the whole cardiac cycle within 5 minutes without degrading the overall performance.

Zhang, Chong; Villa-Uriol, Maria-Cruz; Frangi, Alejandro F.

2010-03-01

189

Integration of 3D and 2D imaging data for assured navigation in unknown environments: initial steps  

NASA Astrophysics Data System (ADS)

This paper discusses the initial steps of the development of a novel navigation method that integrates three-dimensional (3D) point cloud data, two-dimensional (2D) gray-level (intensity), and data from an Inertial Measurement Unit (IMU). A time-of-flight camera such as MESA's Swissranger will output both the 3D and 2D data. The target application is position and attitude determination of unmanned aerial vehicles (UAV) and autonomous ground vehicles (AGV) in urban or indoor environments. In urban and indoor environments a GPS position capability may not only be unavailable due to shadowing, significant signal attenuation or multipath, but also due to intentional denial or deception. The proposed algorithm extracts key features such as planar surfaces, lines and corner-points from both the 3D (point-cloud) and 2D (intensity) imagery. Consecutive observations of corresponding features in the 3D and 2D image frames are then used to compute estimates of position and orientation changes. Since the use of 3D image features for positioning suffers from limited feature observability resulting in deteriorated position accuracies, and the 2D imagery suffers from an unknown depth when estimating the pose from consecutive image frames, it is expected that the integration of both data sets will alleviate the problems with the individual methods resulting in an position and attitude determination method with a high level of assurance. An Inertial Measurement Unit (IMU) is used to set up the tracking gates necessary to perform data association of the features in consecutive frames. Finally, the position and orientation change estimates can be used to correct for the IMU drift errors.

Dill, Evan; Uijt de Haag, Maarten

2009-05-01

190

2-D Precise Radiation Mapping of Sedimentary Core Using Imaging Plate  

NASA Astrophysics Data System (ADS)

The imaging plate (IP) is a storage film coated with photostimulated phosphor (BaFBr: Eu2+), and the latent images produced by irradiation of the imaging plate are read by superficial scanning with stimulation light and are reconstructed as two-dimensional dot images on a computer display. It has an excellent performance for radiation detection, and its advantages include an ease of use, a high position resolution (up to 25ƒÊm), a large detection area (up to 35'43cm2), a high detection sensitivity with high signal-to- noise ratio, an extremely wide dynamic range of dose, a sensitivity to several kinds of radiation, and an erasing capability for reuse (Hareyama et al., 2000). In this study, in order to develop a nondestructive, precise and large area evaluation method of sedimentary structure, an application of autoradiography using IP is attempted to marine sediments. Imaging plate (BAS-MS2040 Fujifilm Co. Ltd., 20'~40 cm2) was cut into rectangular five pieces (4'~40 cm2). Whole round marine sedimentary cores were divided into two half for duplicate and they were covered with a plastic wrap. The rectangular IP were put along the center line of plane side of half round. The exposure in the low temperature was for 48 hours in a shield box. The latent images produced by irradiation of the IP were read out by using the BAS-2500 imaging analyzer (Fujifilm Co. Ltd.). Radiation dose of IP is output as PSL value, that is unique dose units and quantities of IP system. Position resolution was set to 50ƒÊm. Marine sedimentary cores including volcanic ash layer were measured using IP and Natural Gamma Logger (NGL), which is measuring instrument for marine sediments in practice use, to compare their measuring ability. As a result of experiment, it becomes clear that high dose distribution is found at volcanic ash layer with IP, meanwhile it can't be found with NGL. The content of radiation source in volcanic ash layer is supposed to be high compared with other layers because minerals tend to have more potassium, uranium and other radioactive elements than other layer components, for example, organic materials and biotic shells. It can be said that IP has high position resolution and detection sensitivity to figure out the dose distribution from volcanic ash layer. In order to understand relationships between dose and physical properties of marine sedimentary cores, several cores were measured using IP, Multi Sensor Core Logger (MSCL), and X-ray CT scanner. Density, p- wave velocity, resistivity, and magnetic susceptibility were measured by using MSCL, and density showed a good relation with PSL value. Although X-ray CT Scanner is used for visualization of cores, in order to compare the result of CT with the result of IP numerically, CT value that depends on density of materials is used. As a result of it, CT value showed a good relation with PSL value and taken into the dependence of CT value on density and the result of MSCL, it can be said that there is a strong dependence of dose on density in marine sediments.

Sugihara, M.; Tsuchiya, N.

2006-12-01

191

Interobserver, Intraobserver and Intrapatient Reliability Scores of Myocardial Strain Imaging with 2-D Echocardiography in Patients Treated with Anthracyclines  

Microsoft Academic Search

Myocardial strain imaging with 2-D echocardiography is a relatively new noninvasive method to assess myocardial deformation. To determine the interobserver, intraobserver and intrapatient reliability scores, we evaluated myocardial strain measurements of 10 asymptomatic survivors of childhood cancer. Ten patients were selected randomly out of a follow-up cohort of childhood cancer survivors. All 10 patients underwent a transthoracic echocardiographic examination. Two-dimensional

Annelies M. C. Mavinkurve-Groothuis; Gert Weijers; Jacqueline Groot-Loonen; Milanthy Pourier; Ton Feuth; Chris L. de Korte; Peter M. Hoogerbrugge; Livia Kapusta

2009-01-01

192

Circumferential 2D-strain imaging for the prediction of long term response to cardiac resynchronization therapy  

Microsoft Academic Search

BACKGROUND: Cardiac Resynchronization Therapy (CRT) leads to hemodynamic and clinical improvement in heart failure patients. The established methods to evaluate myocardial asynchrony analyze longitudinal and radial myocardial function. This study evaluates the new method of circumferential 2D-strain imaging in the prediction of the long-term response to CRT. METHODS AND RESULTS: 38 heart failure patients (NYHA II-III, QRS > 120 ms,

Fabian Knebel; Sebastian Schattke; Hansjürgen Bondke; Stephan Eddicks; Andrea Grohmann; Gert Baumann; Adrian C Borges

2008-01-01

193

Quantitative Measurements on the Human Ascending Aortic Flow Using 2D Cine Phase-Contrast Magnetic Resonance Imaging  

Microsoft Academic Search

The flow in the human ascending aorta was quantified using two-dimensional (2D) cine phase-contrast magnetic resonance imaging (MRI). The quality and reliability of the method were demonstrated with a specially designed phantom model; the flow rate determined with the MRI agreed well with that obtained with a measuring cylinder. The method was then used to measure the aortic blood flow

Suguru Yokosawa; Masanori Nakamura; Shigeo Wada; Haruo Isoda; Hiroyasu Takeda; Takami Yamaguchi

2005-01-01

194

Magnetic Domain Structure of U2D2 Solid 3He by Using the Magnetic Resonance Imaging  

Microsoft Academic Search

A spatial distribution of the magnetic domain structure in the U2D2 phase of solid 3He was examined by a special Magnetic Resonance Imaging (MRI) technique. There were three kinds of magnetic domains in a single seed crystal of a few mm3 size and each domain size was as large as the seed crystal size. We investigated by MRI the distribution

T. Ueno; Y. Kawaguchi; Y. Kinoshita; Y. Sasaki; T. Mizusaki

2002-01-01

195

Ultra High Flux 2-D CdZnTe Monolithic Detector Arrays for X-Ray Imaging Applications  

Microsoft Academic Search

The performance of 2-D CdZnTe monolithic detector arrays designed for high flux X-ray imaging applications was studied. For the first time we have obtained 5 times 106 counts\\/s\\/mm2 count-rate for a CdZnTe pixelated detector array. This count-rate is more than twice the highest count-rate ever achieved using a CdZnTe detector array. Such excellent performance was demonstrated for more than 600

Csaba Szeles; Stephen A. Soldner; Steve Vydrin; Jesse Graves; Derek S. Bale

2007-01-01

196

A challenge problem for 2D\\/3D imaging of targets from a volumetric data set in an urban environment  

Microsoft Academic Search

This paper describes a challenge problem whose scope is the 2D\\/3D imaging of stationary targets from a volumetric data set of X-band Synthetic Aperture Radar (SAR) data collected in an urban environment. The data for this problem was collected at a scene consisting of numerous civilian vehicles and calibration targets. The radar operated in circular SAR mode and completed 8

Curtis H. Casteel Jr.; LeRoy A. Gorham; Michael J. Minardi; Steven M. Scarborough; Kiranmai D. Naidu; Uttam K. Majumder

2007-01-01

197

Low dose X-ray phase contrast imaging sensitive to phase effects in 2-D  

Microsoft Academic Search

X-ray absorption imaging is a widespread imaging technique in biology and industry as well as diagnostic imaging of the human body in medicine. However, in many situations, there is the need to distinguish between low absorption and even low contrast features such as cancerous and normal tissue in mammography. In this case, the applicability of conventional absorption imaging is limited.

Frantisek Krejci; Jan Jakubek; Martin Kroupa

2010-01-01

198

Experimental validation of 2D uncertainty quantification for digital image correlation  

Microsoft Academic Search

Because digital image correlation (DIC) has become such an important and standard tool in the toolbox of experimental mechanicists, a complete uncertainty quantification of the method is needed. It should be remembered that each DIC setup and series of images will have a unique uncertainty based on the calibration quality and the image and speckle quality of the analyzed images.

P. L. Reu; Phillip L

2010-01-01

199

Adaptive clutter filter in 2-D color flow imaging based on in vivo I/Q signal.  

PubMed

Color flow imaging has been well applied in clinical diagnosis. For the high quality color flow images, clutter filter is important to separate the Doppler signals from blood and tissue. Traditional clutter filters, such as finite impulse response, infinite impulse response and regression filters, were applied, which are based on the hypothesis that the clutter signal is stationary or tissue moves slowly. However, in realistic clinic color flow imaging, the signals are non-stationary signals because of accelerated moving tissue. For most related papers, simulated RF signals are widely used without in vivo I/Q signal. Hence, in this paper, adaptive polynomial regression filter, which is down mixing with instantaneous clutter frequency, was proposed based on in vivo carotid I/Q signal in realistic color flow imaging. To get the best performance, the optimal polynomial order of polynomial regression filter and the optimal polynomial order for estimation of instantaneous clutter frequency respectively were confirmed. Finally, compared with the mean blood velocity and quality of 2-D color flow image, the experiment results show that adaptive polynomial regression filter, which is down mixing with instantaneous clutter frequency, can significantly enhance the mean blood velocity and get high quality 2-D color flow image. PMID:24211911

Zhou, Xiaoming; Zhang, Congyao; Liu, Dong C

2014-01-01

200

A challenge problem for 2D/3D imaging of targets from a volumetric data set in an urban environment  

NASA Astrophysics Data System (ADS)

This paper describes a challenge problem whose scope is the 2D/3D imaging of stationary targets from a volumetric data set of X-band Synthetic Aperture Radar (SAR) data collected in an urban environment. The data for this problem was collected at a scene consisting of numerous civilian vehicles and calibration targets. The radar operated in circular SAR mode and completed 8 circular flight paths around the scene with varying altitudes. Data consists of phase history data, auxiliary data, processing algorithms, processed images, as well as ground truth data. Interest is focused on mitigating the large side lobes in the point spread function. Due to the sparse nature of the elevation aperture, traditional imaging techniques introduce excessive artifacts in the processed images. Further interests include the formation of highresolution 3D SAR images with single pass data and feature extraction for 3D SAR automatic target recognition applications. The purpose of releasing the Gotcha Volumetric SAR Data Set is to provide the community with X-band SAR data that supports the development of new algorithms for high-resolution 2D/3D imaging.

Casteel, Curtis H., Jr.; Gorham, LeRoy A.; Minardi, Michael J.; Scarborough, Steven M.; Naidu, Kiranmai D.; Majumder, Uttam K.

2007-04-01

201

Using artificial neural networks to invert 2D DC resistivity imaging data for high resistivity contrast regions: A MATLAB application  

NASA Astrophysics Data System (ADS)

MATLAB is a high-level matrix/array language with control flow statements and functions. MATLAB has several useful toolboxes to solve complex problems in various fields of science, such as geophysics. In geophysics, the inversion of 2D DC resistivity imaging data is complex due to its non-linearity, especially for high resistivity contrast regions. In this paper, we investigate the applicability of MATLAB to design, train and test a newly developed artificial neural network in inverting 2D DC resistivity imaging data. We used resilient propagation to train the network. The model used to produce synthetic data is a homogeneous medium of 100 ? m resistivity with an embedded anomalous body of 1000 ? m. The location of the anomalous body was moved to different positions within the homogeneous model mesh elements. The synthetic data were generated using a finite element forward modeling code by means of the RES2DMOD. The network was trained using 21 datasets and tested on another 16 synthetic datasets, as well as on real field data. In field data acquisition, the cable covers 120 m between the first and the last take-out, with a 3 m x-spacing. Three different electrode spacings were measured, which gave a dataset of 330 data points. The interpreted result shows that the trained network was able to invert 2D electrical resistivity imaging data obtained by a Wenner-Schlumberger configuration rapidly and accurately.

Neyamadpour, Ahmad; Taib, Samsudin; Wan Abdullah, W. A. T.

2009-11-01

202

Novel three-dimensional imaging volumetry in autosomal dominant polycystic kidney disease: comparison with 2D volumetry.  

PubMed

Background: Autosomal dominant polycystic kidney disease (ADPKD) volumetry is an important marker for evaluating the progression of disease. Three-dimensional (3D) volumetry is generally more timesaving than 2D volumetry, but its reliability and accuracy are uncertain. Methods: Small and large phantoms simulating polycystic kidneys and 20 patients with ADPKD underwent magnetic resonance imaging (MRI) volumetry. We evaluated the total kidney volume (TKV) and total cyst volume (TCV) using a novel 3D volumetry program (XelisTM) and compared 3D volumetry data with the conventional 2D method (the reference volume values). After upload and threshold setting, the other organs surrounding the kidney were removed by picking and sculpting. The novel method involves drawing of the kidney or cyst and automatic measurement of kidney volume and cyst volume in 3D images. Results: The 3D volume estimation of the small and large phantoms differed from the actual values by 6.9% and -8.2%, respectively, for TKV and by 2.1% and 1.4% for TCV. In ADPKD patients, the intra-reader reliability of 3D volumetry was 30 ± 180 mL (1.3 ± 10.3%) and 25 ± 113 mL (1.2 ± 9.4%), respectively, for TKV and TCV. Correlation between 3D volumetry and 2D volumetry of TKV and TCV resulted in a high correlation coefficient and a regression slope approaching 1.00 (r = 0.97 - 0.98). The mean of the volume percentage differences for 3D vs. 2D for TKV : TCV were -6.0 ± 8.9% : 2.0 ± 11.8% in large ADPKD and -16.1 ± 10.4% : 13.2 ± 21.9% in small ADPKD. Conclusion: Our study showed that 3D volumetry has reliability and accuracy compared with 2D volumetry in ADPKD. 3D volumetry is more accurate for TCV and large ADPKD. PMID:25029513

Shin, Dongsuk; Lee, Kyu-Beck; Hyun, Young Youl; Lee, Young Rae; Hwang, Young-Hwan; Park, Hayne Cho; Ahn, Curie

2014-08-01

203

2-D simulation and analysis of temperature effects on electrical parameters degradation of power RF LDMOS device  

NASA Astrophysics Data System (ADS)

This paper presents a synthesis of temperature effects on power RF Laterally Diffused (LD) MOS performances, which can modify and degrade transistor physical and electrical behaviour. In this work, the temperature influence on device electrical characteristics is discussed with regard to physical limits for device operation. A developed 2-D structure was implemented and simulated using the physical simulator Silvaco-Atlas to explain the observed data and offer insight into the physical origin of LDMOS temperature behaviour. The temperature dependence of most important electrical parameters such as channel current Ids, threshold voltage Vth and inter-electrodes capacitances ( Cds, Cgs) is investigated. The temperature effects on mobility, electron concentration, electric field, current flow lines and Fermi level are taken into account. Finally, initial failure analysis is discussed.

Belaïd, M. A.; Ketata, K.; Gares, M.; Marcon, J.; Mourgues, K.; Masmoudi, M.

2006-12-01

204

Cerebral microbleeds: Accelerated 3D T2*-weighted GRE MR imaging versus conventional 2D T2*-weighted GRE MR imaging for detection  

Microsoft Academic Search

The purpose of this study was to prospectively compare high-spatial- resolution accelerated three-dimensional (3D) T2*-weighted gradient-recalled-echo (GRE) magnetic resonance (MR) images with conventional two-dimensional (2D) T2*-weighted GRE MR images for the depiction of cerebral microbleeds. After obtaining institutional review board approval and informed consent, 200 elderly participants (age range, 69.7-96.7 years; 108 [54%] women) were imaged at 1.5 T by

M. W. Vernooij; M. A. Ikram; P. A. Wielopolski; G. P. Krestin; M. M. B. Breteler; A. van der Lugt

2008-01-01

205

Microphysical Analysis using Airborne 2-D Cloud and Precipitation Imaging Probe Data  

NASA Astrophysics Data System (ADS)

The NOAA P-3 instrumented aircraft provided in-situ cloud and precipitation microphysical observations during the DYNAMO (Dynamics of the Madden-Julian Oscillation) field experiment. The Particle Measuring System 2D cloud (2D-C) and precipitation (2D-P) probes collected data for particles between 12.5 ?m - 1.55 mm (25 ?m resolution) and 100 ?m - 6.2 mm (100 ?m resolution), respectively. Spectra from each instrument were combined to provide a broad distribution of precipitation particle sizes. The 'method of moments' technique was used to analyze drop size distribution (DSD) spectra, which were modeled by fitting a three-parameter (slope, shape, and intercept) gamma distribution to the spectra. The characteristic shape of the mean spectrum compares to previous maritime measurements. DSD variability will be presented with respect to the temporal evolution of cloud populations during a Madden-Julian Oscillation (MJO) event, as well as in-situ aircraft vertical wind velocity measurements. Using the third and sixth moments, rainfall rate (R) and equivalent radar reflectivity factor (Z), respectively, were computed for each DSD. Linear regression was applied to establish a Z-R relationship for the data for the estimation of precipitation. The study indicated unique characteristics of microphysical processes for this region. These results are important to continue to define the cloud population characteristics in the climatological MJO region. Improved representation of the cloud characteristics on the microphysical scale will serve as a check to model parameterizations, helping to improve numerical simulations.

Guy, N.; Jorgensen, D.; Witte, M.; Chuang, P. Y.; Black, R. A.

2013-12-01

206

The effect of out-of-plane motion on 2D and 3D digital image correlation measurements  

Microsoft Academic Search

The effect of out-of-plane motion (including out-of-plane translation and rotation) on two-dimensional (2D) and three-dimensional (3D) digital image correlation measurements is demonstrated using basic theoretical pinhole image equations and experimentally through synchronized, multi-system measurements. Full-field results obtained during rigid body, out-of-plane motion using a single-camera vision system with (a-1) a standard f55mm Nikon lens and (a-2) a single Schneider–Kreuznach Xenoplan

M. A. Sutton; J. H. Yan; V. Tiwari; H. W. Schreier; J. J. Orteu

2008-01-01

207

Auto-masked 2D/3D image registration and its validation with clinical cone-beam computed tomography  

NASA Astrophysics Data System (ADS)

Image-guided alignment procedures in radiotherapy aim at minimizing discrepancies between the planned and the real patient setup. For that purpose, we developed a 2D/3D approach which rigidly registers a computed tomography (CT) with two x-rays by maximizing the agreement in pixel intensity between the x-rays and the corresponding reconstructed radiographs from the CT. Moreover, the algorithm selects regions of interest (masks) in the x-rays based on 3D segmentations from the pre-planning stage. For validation, orthogonal x-ray pairs from different viewing directions of 80 pelvic cone-beam CT (CBCT) raw data sets were used. The 2D/3D results were compared to corresponding standard 3D/3D CBCT-to-CT alignments. Outcome over 8400 2D/3D experiments showed that parametric errors in root mean square were <0.18° (rotations) and <0.73 mm (translations), respectively, using rank correlation as intensity metric. This corresponds to a mean target registration error, related to the voxels of the lesser pelvis, of <2 mm in 94.1% of the cases. From the results we conclude that 2D/3D registration based on sequentially acquired orthogonal x-rays of the pelvis is a viable alternative to CBCT-based approaches if rigid alignment on bony anatomy is sufficient, no volumetric intra-interventional data set is required and the expected error range fits the individual treatment prescription.

Steininger, P.; Neuner, M.; Weichenberger, H.; Sharp, G. C.; Winey, B.; Kametriser, G.; Sedlmayer, F.; Deutschmann, H.

2012-07-01

208

Stochastic Tracking of 3D Human Figures Using 2D Image Motion  

Microsoft Academic Search

A probabilistic method for tracking 3D articulated human figures in monocular image sequences is presented. Within a Bayesian framework, we define a generative model of image appearance, a robust likelihood function based on image graylevel differences, and a prior pro- bability distribution over pose and joint angles that models how humans move. The posterior probability distribution over model parameters is

Hedvig Sidenbladh; Michael J. Black; David J. Fleet

2000-01-01

209

2D-3D registration for prostate radiation therapy based on a statistical model of transmission images  

SciTech Connect

Purpose: In external beam radiation therapy of pelvic sites, patient setup errors can be quantified by registering 2D projection radiographs acquired during treatment to a 3D planning computed tomograph (CT). We present a 2D-3D registration framework based on a statistical model of the intensity values in the two imaging modalities. Methods: The model assumes that intensity values in projection radiographs are independently but not identically distributed due to the nonstationary nature of photon counting noise. Two probability distributions are considered for the intensity values: Poisson and Gaussian. Using maximum likelihood estimation, two similarity measures, maximum likelihood with a Poisson (MLP) and maximum likelihood with Gaussian (MLG), distribution are derived. Further, we investigate the merit of the model-based registration approach for data obtained with current imaging equipment and doses by comparing the performance of the similarity measures derived to that of the Pearson correlation coefficient (ICC) on accurately collected data of an anthropomorphic phantom of the pelvis and on patient data. Results: Registration accuracy was similar for all three similarity measures and surpassed current clinical requirements of 3 mm for pelvic sites. For pose determination experiments with a kilovoltage (kV) cone-beam CT (CBCT) and kV projection radiographs of the phantom in the anterior-posterior (AP) view, registration accuracies were 0.42 mm (MLP), 0.29 mm (MLG), and 0.29 mm (ICC). For kV CBCT and megavoltage (MV) AP portal images of the same phantom, registration accuracies were 1.15 mm (MLP), 0.90 mm (MLG), and 0.69 mm (ICC). Registration of a kV CT and MV AP portal images of a patient was successful in all instances. Conclusions: The results indicate that high registration accuracy is achievable with multiple methods including methods that are based on a statistical model of a 3D CT and 2D projection images.

Munbodh, Reshma; Tagare, Hemant D.; Chen Zhe; Jaffray, David A.; Moseley, Douglas J.; Knisely, Jonathan P. S.; Duncan, James S. [Department of Radiology, Weill Medical College of Cornell University, New York, New York 10021 (United States); Department of Biomedical Engineering, Yale University, Connecticut 06520 and Department of Diagnostic Radiology, School of Medicine, Yale University, Connecticut 06520 (United States); Department of Therapeutic Radiology, School of Medicine, Yale University, Connecticut 06520 (United States); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G-2M9 (Canada); Department of Therapeutic Radiology, School of Medicine, Yale University, Connecticut 06520 (United States); Department of Biomedical Engineering, Yale University, Connecticut 06520 and Department of Diagnostic Radiology, School of Medicine, Yale University, Connecticut 06520 (United States)

2009-10-15

210

2D and 3D imaging resolution trade-offs in quantifying pore throats for prediction of permeability  

SciTech Connect

Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging technique and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability esti- mates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 lm predicted permeabilities differ- ing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-res- olution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability pre- dictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of permeability will result from images between 2 and 4 lm resolution. To reduce permeability underestimation from analyses of high-resolu- tion images, a resolution threshold between 3 and 15 lm was found to be effective, but it is not known whether this range is applicable beyond the samples studied here.

Beckingham, Lauren E.; Peters, Catherine A.; Um, Wooyong; Jones, Keith W.; Lindquist, W.Brent

2013-09-03

211

2D and 3D imaging resolution trade-offs in quantifying pore throats for prediction of permeability  

NASA Astrophysics Data System (ADS)

Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging technique and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability estimates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 ?m predicted permeabilities differing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-resolution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability predictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of permeability will result from images between 2 and 4 ?m resolution. To reduce permeability underestimation from analyses of high-resolution images, a resolution threshold between 3 and 15 ?m was found to be effective, but it is not known whether this range is applicable beyond the samples studied here.

Beckingham, L. E.; Peters, C. A.; Um, W.; Jones, K. W.; Lindquist, W. B.

2013-12-01

212

Segmentation of 2D fetal ultrasound images by exploiting context information using conditional random fields.  

PubMed

This paper proposes a novel approach for segmenting fetal ultrasound images. This problem presents a variety of challenges including high noise, low contrast, and other US imaging properties such as similarity between texture and gray levels of two organs/ tissues. In this paper, we have proposed a Conditional Random Field (CRF) based framework to handle challenges in segmenting fetal ultrasound images. Clinically, it is known that fetus is surrounded by specific maternal tissues, amniotic fluid and placenta. We exploit this context information using CRFs for segmenting the fetal images accurately. The proposed CRF framework uses wavelet based texture features for representing the ultrasound image and Support Vector Machines (SVM) for initial label prediction. Initial results on a limited dataset of real world ultrasound images of fetus are promising. Results show that proposed method could handle the noise and similarity between fetus and its surroundings in ultrasound images. PMID:22256004

Gupta, Lalit; Sisodia, Rajendra Singh; Pallavi, V; Firtion, Celine; Ramachandran, Ganesan

2011-01-01

213

A Detector for 2-D Neutron Imaging for the Spallation Neutron Source  

SciTech Connect

Abstract - We have designed, built, and tested a 2-D pixellated thermal neutron detector. The detector is modeled after the MicroMegas-type structure previously published for collider-type experiments. The detector consists of a 4X4 square array of 1 cm 2 pixels each of which is connected to an individual preamplifier-shaper-data acquisition system. The neutron converter is a 10B film on an aluminum substrate. We describe the construction of the detector and the test results utilizing 252Cf sources in Lucite to thermalize the neutrons.Drift electrode (Aluminum) Converter (10B) 3 mm Conversion gap neutron (-900 V)

Britton Jr, Charles L [ORNL; Bryan, W. L. [Oak Ridge National Laboratory (ORNL); Wintenberg, Alan Lee [ORNL; Clonts, Lloyd G [ORNL; Warmack, Robert J Bruce [ORNL; McKnight, Timothy E [ORNL; Frank, Steven Shane [ORNL; Cooper, Ronald G [ORNL; Dudney, Nancy J [ORNL; Veith, Gabriel M [ORNL

2006-01-01

214

Full 2D displacement vector and strain tensor estimation for superficial tissue using beam-steered ultrasound imaging.  

PubMed

Ultrasound strain imaging is used to measure local tissue deformations. Usually, only strains along the ultrasound beam are estimated, because those estimates are most precise, due to the availability of phase information. For estimating strain in other directions we propose to steer the ultrasound beam at an angle, which allows estimating different projections of the 2D strain tensor, while phase information remains available. This study investigates beam steering at maximally three different angles to determine the full 2D strain tensor. The method was tested on simulated and experimental data of an inclusion phantom and a vessel phantom. The combination of data from a non-steered acquisition and acquisitions at a large positive and an equally large but negative steering angle enabled the most precise estimation of the strain components. The method outperforms conventional methods that do not use beam steering. PMID:20479516

Hansen, H H G; Lopata, R G P; Idzenga, T; de Korte, C L

2010-06-01

215

Experimental demonstration of diffusion signal enhancement in 2D DESIRE images  

NASA Astrophysics Data System (ADS)

In magnetic resonance microscopy based on conventional Fourier encoding techniques, molecular self-diffusion leads to a loss in signal to noise ratio while also limiting the spatial resolution. As opposed to standard diffusion-weighted sequences, the DESIRE (Diffusion Enhancement of SIgnal and REsolution) method gains signal through diffusion via a signal difference measurement, corresponding to the total number of spins saturated by a localized pulse applied for a given amount of time. The higher the diffusion coefficient at that location, the larger the number of spins effectively saturated and thus the higher the difference in signal. While the method has been previously demonstrated in 1D, the availability of higher magnetic fields and gradient strengths has recently brought its development within reach in 2D. Here we report the implementation of 2D DESIRE and the first experimental evaluation of enhancements in water and thin silicone oil. Enhancement levels obtained by saturating a 60 ?m diameter region (effectively ˜140 ?m) and allowing diffusion lengths of 28 ?m or 7 ?m, respectively, are consistent with theoretical predictions. The typical enhancement values are 100% in water and 20% in silicone oil.

Jelescu, Ileana O.; Boulant, Nicolas; Le Bihan, Denis; Ciobanu, Luisa

2012-05-01

216

Reconstruction of biliary structure in 2D MRCP images using multi-scale analysis  

Microsoft Academic Search

Magnetic resonance cholangio pancreatography (MRCP) has become a reference technique for biliary tree analysis. Typical MRCP images, however, suffer from difficulty in distinguishing the structure of the biliary tree in order to identify abnormalities, for clinical diagnosis. For efficiency in analysing MRCP image series, the need arises for the use of semi-automated image processing techniques. A segment-based multi-scale approach is

Rajasvaran Logeswaran

2008-01-01

217

2D and 3D MALDI-imaging: conceptual strategies for visualization and data mining.  

PubMed

3D imaging has a significant impact on many challenges in life sciences, because biology is a 3-dimensional phenomenon. Current 3D imaging-technologies (various types MRI, PET, SPECT) are labeled, i.e. they trace the localization of a specific compound in the body. In contrast, 3D MALDI mass spectrometry-imaging (MALDI-MSI) is a label-free method imaging the spatial distribution of molecular compounds. It complements 3D imaging labeled methods, immunohistochemistry, and genetics-based methods. However, 3D MALDI-MSI cannot tap its full potential due to the lack of statistical methods for analysis and interpretation of large and complex 3D datasets. To overcome this, we established a complete and robust 3D MALDI-MSI pipeline combined with efficient computational data analysis methods for 3D edge preserving image denoising, 3D spatial segmentation as well as finding colocalized m/z values, which will be reviewed here in detail. Furthermore, we explain, why the integration and correlation of the MALDI imaging data with other imaging modalities allows to enhance the interpretation of the molecular data and provides visualization of molecular patterns that may otherwise not be apparent. Therefore, a 3D data acquisition workflow is described generating a set of 3 different dimensional images representing the same anatomies. First, an in-vitro MRI measurement is performed which results in a three-dimensional image modality representing the 3D structure of the measured object. After sectioning the 3D object into N consecutive slices, all N slices are scanned using an optical digital scanner, enabling for performing the MS measurements. Scanning the individual sections results into low-resolution images, which define the base coordinate system for the whole pipeline. The scanned images conclude the information from the spatial (MRI) and the mass spectrometric (MALDI-MSI) dimension and are used for the spatial three-dimensional reconstruction of the object performed by image registration techniques. Different strategies for automatic serial image registration applied to MS datasets are outlined in detail. The third image modality is histology driven, i.e. a digital scan of the histological stained slices in high-resolution. After fusion of reconstructed scan images and MRI the slice-related coordinates of the mass spectra can be propagated into 3D-space. After image registration of scan images and histological stained images, the anatomical information from histology is fused with the mass spectra from MALDI-MSI. As a result of the described pipeline we have a set of 3 dimensional images representing the same anatomies, i.e. the reconstructed slice scans, the spectral images as well as corresponding clustering results, and the acquired MRI. Great emphasis is put on the fact that the co-registered MRI providing anatomical details improves the interpretation of 3D MALDI images. The ability to relate mass spectrometry derived molecular information with in vivo and in vitro imaging has potentially important implications. This article is part of a Special Issue entitled: Computational Proteomics in the Post-Identification Era. Guest Editors: Martin Eisenacher and Christian Stephan. PMID:23467008

Thiele, Herbert; Heldmann, Stefan; Trede, Dennis; Strehlow, Jan; Wirtz, Stefan; Dreher, Wolfgang; Berger, Judith; Oetjen, Janina; Kobarg, Jan Hendrik; Fischer, Bernd; Maass, Peter

2014-01-01

218

Assessing 3D tunnel position in ACL reconstruction using a novel single image 3D-2D registration  

NASA Astrophysics Data System (ADS)

The routinely used procedure for evaluating tunnel positions following anterior cruciate ligament (ACL) reconstructions based on standard X-ray images is known to pose difficulties in terms of obtaining accurate measures, especially in providing three-dimensional tunnel positions. This is largely due to the variability in individual knee joint pose relative to X-ray plates. Accurate results were reported using postoperative CT. However, its extensive usage in clinical routine is hampered by its major requirement of having CT scans of individual patients, which is not available for most ACL reconstructions. These difficulties are addressed through the proposed method, which aligns a knee model to X-ray images using our novel single-image 3D-2D registration method and then estimates the 3D tunnel position. In the proposed method, the alignment is achieved by using a novel contour-based 3D-2D registration method wherein image contours are treated as a set of oriented points. However, instead of using some form of orientation weighting function and multiplying it with a distance function, we formulate the 3D-2D registration as a probability density estimation using a mixture of von Mises-Fisher-Gaussian (vMFG) distributions and solve it through an expectation maximization (EM) algorithm. Compared with the ground-truth established from postoperative CT, our registration method in an experiment using a plastic phantom showed accurate results with errors of (-0.43°+/-1.19°, 0.45°+/-2.17°, 0.23°+/-1.05°) and (0.03+/-0.55, -0.03+/-0.54, -2.73+/-1.64) mm. As for the entry point of the ACL tunnel, one of the key measurements, it was obtained with high accuracy of 0.53+/-0.30 mm distance errors.

Kang, X.; Yau, W. P.; Otake, Y.; Cheung, P. Y. S.; Hu, Y.; Taylor, R. H.

2012-02-01

219

2D-FEM analysis of rolls temperature field in induction heating process  

NASA Astrophysics Data System (ADS)

Hot-roller warm rolling process is expected to achieve a breakthrough in solving the problem of high quality rolling for difficult deformed metals. In this paper roll surface induction heating was studied based on the finite element theory of electromagnetic-thermal coupling and experiment. The law of temperature field for a static roll in induction heating process was analyzed by FEM. The results show that roll surface temperature can achieve 721°C at 48s under 20000Hz power frequency, 350×104A/m2 current density, due to the skin effect on roll surface. Using a special induction coil in the laboratory, an experiment of roll induction heating was carried out with the same process parameters. The calculated results of temperature on roll surface agree well with the measured value.

Cai, Ban; Wang, Hao; Mei, Ruibin; Li, Changsheng

2013-05-01

220

Direct observation of ground-state lactam-lactim tautomerization using temperature-jump transient 2D IR spectroscopy  

PubMed Central

We provide a systematic characterization of the nanosecond ground-state lactam–lactim tautomerization of pyridone derivatives in aqueous solution under ambient conditions using temperature-jump transient 2D IR spectroscopy. Although electronic excited-state tautomerization has been widely studied, experimental work on the ground electronic state, most relevant to chemistry and biology, is lacking. Using 2D IR spectroscopy, lactam and lactim tautomers of 6-chloro-2-pyridone and 2-chloro-4-pyridone are unambiguously identified by their unique cross-peak patterns. Monitoring the correlated exponential relaxation of these signals in response to a laser temperature jump provides a direct measurement of the nanosecond tautomerization kinetics. By studying the temperature, concentration, solvent, and pH dependence, we extract a thermodynamic and kinetic characterization and conclude that the tautomerization proceeds through a two-state concerted mechanism. We find that the intramolecular proton transfer is mediated by bridging water molecules and the reaction barrier is dictated by the release of a proton from pyridone, as would be expected for an efficient Grothuss-type proton transfer mechanism.

Peng, Chunte Sam; Baiz, Carlos R.; Tokmakoff, Andrei

2013-01-01

221

A 2-D gel electrophoresis DNA image analysis algorithm with automatic thresholding  

NASA Astrophysics Data System (ADS)

Polymerase chain reaction (PCR) and gel electrophoresis are two widely used techniques for genetic studies that require the bench scientist to perform many tedious manual steps. Advances in automation are making these techniques more accessible, but detection and image analysis still remain labor-intensive. Although several commercial software packages are now available, DNA image analysis still requires some intervention by the user, and thus a certain level of image processing expertise. To allow researchers to speed up their analyses and obtain more repeatable results, we present a fully automated image analysis system for DNA or protein studies with high accuracy. The proposed system is based mainly on four steps: automatic thresholding, shifting, filtering, and processing. The automatic thresholding that is used to equalize the gray values of the gel electrophoreses image background is one of the key and novel operations in this algorithm. An enhancement is also used to improve poor quality images that have faint DNA bands. Experimental results show that the proposed method eliminates defects due to noise for good and average quality gel electrophoresis images, while it also improves the appearance of poor quality images.

Kaabouch, Naima; Schultz, Richard R.

2007-01-01

222

Application of Kohonen network for automatic point correspondence in 2D medical images.  

PubMed

In this paper, a generalized application of Kohonen Network for automatic point correspondence of unimodal medical images is presented. Given a pair of two-dimensional medical images of the same anatomical region and a set of interest points in one of the images, the algorithm detects effectively the set of corresponding points in the second image, by exploiting the properties of the Kohonen self organizing maps (SOMs) and embedding them in a stochastic optimization framework. The correspondences are established by determining the parameters of local transformations that map the interest points of the first image to their corresponding points in the second image. The parameters of each transformation are computed in an iterative way, using a modification of the competitive learning, as implemented by SOMs. The proposed algorithm was tested on medical imaging data from three different modalities (CT, MR and red-free retinal images) subject to known and unknown transformations. The quantitative results in all cases exhibited sub-pixel accuracy. The algorithm also proved to work efficiently in the case of noise corrupted data. Finally, in comparison to a previously published algorithm that was also based on SOMs, as well as two widely used techniques for detection of point correspondences (template matching and iterative closest point), the proposed algorithm exhibits an improved performance in terms of accuracy and robustness. PMID:19481734

Markaki, Vasiliki E; Asvestas, Pantelis A; Matsopoulos, George K

2009-07-01

223

Image reconstruction of 2D concentration distribution of particle flow with extinction optical tomography  

Microsoft Academic Search

Optical tomography, as a novel technique developed recently, has drawn more and more interest among imaging of biology tissue, astronomy and industrial process monitoring, and so on. Extinction method is one of traditional measurement for particle concentration, which can be improve a novel optical measurement with computed tomography (CT) to reconstruct image of particle concentration distribution. In this paper, the

Yang Li; Renhuang Wang; Yingna Zheng

2003-01-01

224

Registration vs. Reconstruction: Incorporating Structural Constraint in Building 3-D Models from 2-D Microscopy Images  

Microsoft Academic Search

Registration is the key step for 3-D reconstruction of mi- croanatomical structures from large number of microscopy images of biomedical samples. However, in most current approaches, 3-D structural information is not incorporated in the registration process. We present a novel approach by integrating structural constraints into the reconstruction pipeline. In stead of registering each image to its neighbors, we transform

Lee Cooper; Kun Huang; Ashish Sharma; Kishore Mosaliganti; Tony Pan; Antony Trimboli; Michael Ostrowski

225

Characteristics of active and passive 2-D holographic scanner imaging systems for the middle infrared  

Microsoft Academic Search

Holographic scanners are suggested for imaging in the 8-13 micron spectral region. Advantages in refrigeration and reliability are pointed out. The narrow linewidth of received irradiance may limit passive systems to applications such as thermography, where multispectral imaging should be a useful diagnostic tool. Active systems, which do not suffer from this range limitation, offer inherent advantages with regard to

C. S. Ih; E. Ledet; N. S. Kopeika

1980-01-01

226

Investigating large 2D arrays for photoacoustic and acoustic imaging using CMUT technology  

Microsoft Academic Search

In this paper, we investigate using a large aperture (64 times 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller array (16 times 16 elements) of capacitive micromachined ultrasonic transducers (CMUTs). We show results from the imaging of: 1) A fishing-line phantom. 2) Tubes embedded in chicken breast tissue containing the contrast agent indocyanine green

Srikant Vaithilingam; Te-Jen Ma; Yukio Furukawa; Omer Oralkan; Aya Kamaya; Kazutoshi Torashima; Mario Kupnik; Ira O. Wygant; Xuefeng Zhuang; R. B. Jeffrey; Butrus T. Khuri-Yakub

2008-01-01

227

High resolution human diffusion tensor imaging using 2-D navigated multi-shot SENSE EPI at 7 Tesla  

PubMed Central

The combination of parallel imaging with partial Fourier acquisition has greatly improved the performance of diffusion-weighted single-shot EPI and is the preferred method for acquisitions at low to medium magnetic field strength such as 1.5 or 3 Tesla. Increased off-resonance effects and reduced transverse relaxation times at 7 Tesla, however, generate more significant artifacts than at lower magnetic field strength and limit data acquisition. Additional acceleration of k-space traversal using a multi-shot approach, which acquires a subset of k-space data after each excitation, reduces these artifacts relative to conventional single-shot acquisitions. However, corrections for motion-induced phase errors are not straightforward in accelerated, diffusion-weighted multi-shot EPI because of phase aliasing. In this study, we introduce a simple acquisition and corresponding reconstruction method for diffusion-weighted multi-shot EPI with parallel imaging suitable for use at high field. The reconstruction uses a simple modification of the standard SENSE algorithm to account for shot-to-shot phase errors; the method is called Image Reconstruction using Image-space Sampling functions (IRIS). Using this approach, reconstruction from highly aliased in vivo image data using 2-D navigator phase information is demonstrated for human diffusion-weighted imaging studies at 7 Tesla. The final reconstructed images show submillimeter in-plane resolution with no ghosts and much reduced blurring and off-resonance artifacts.

Jeong, Ha-Kyu; Gore, John C.; Anderson, Adam W.

2012-01-01

228

2D and 3D Refraction Based X-ray Imaging Suitable for Clinical and Pathological Diagnosis  

NASA Astrophysics Data System (ADS)

The first observation of micro papillary (MP) breast cancer by x-ray dark-field imaging (XDFI) and the first observation of the 3D x-ray internal structure of another breast cancer, ductal carcinoma in-situ (DCIS), are reported. The specimen size for the sheet-shaped MP was 26 mm × 22 mm × 2.8 mm, and that for the rod-shaped DCIS was 3.6 mm in diameter and 4.7 mm in height. The experiment was performed at the Photon Factory, KEK: High Energy Accelerator Research Organization. We achieved a high-contrast x-ray image by adopting a thickness-controlled transmission-type angular analyzer that allows only refraction components from the object for 2D imaging. This provides a high-contrast image of cancer-cell nests, cancer cells and stroma. For x-ray 3D imaging, a new algorithm due to the refraction for x-ray CT was created. The angular information was acquired by x-ray optics diffraction-enhanced imaging (DEI). The number of data was 900 for each reconstruction. A reconstructed CT image may include ductus lactiferi, micro calcification and the breast gland. This modality has the possibility to open up a new clinical and pathological diagnosis using x-ray, offering more precise inspection and detection of early signs of breast cancer.

Ando, Masami; Bando, Hiroko; Chen, Zhihua; Chikaura, Yoshinori; Choi, Chang-Hyuk; Endo, Tokiko; Esumi, Hiroyasu; Gang, Li; Hashimoto, Eiko; Hirano, Keiichi; Hyodo, Kazuyuki; Ichihara, Shu; Jheon, Sanghoon; Kim, Hongtae; Kim, Jongki; Kimura, Tatsuro; Lee, Changhyun; Maksimenko, Anton; Ohbayashi, Chiho; Park, Sunghwan; Shimao, Daisuke; Sugiyama, Hiroshi; Tang, Jintian; Ueno, Ei; Yamasaki, Katsuhito; Yuasa, Tetsuya

2007-01-01

229

Proton temperature anisotropy and current sheet stability: 2-D hybrid simulations  

NASA Astrophysics Data System (ADS)

The solar wind is a weakly collisional non homogeneous plasma; gradients associated to density, velocity shears and current sheets are often observed. In situ observations also show that the solar wind plasma is far from thermal equilibrium and particle distribution functions are not isotropic. The presence of a temperature anisotropy can be the source of free energy for kinetic instabilities and their unstable fluctuations may grow and propagate in the plasma. However, how these fluctuations evolve in a non homogeneous medium and how they interact and influence local coherent structures, is still an open question. We report preliminary numerical simulations that describe the evolution of current sheets in a non thermal plasma, focusing on the interaction between kinetic effects driven by a proton temperature anisotropy and magnetic reconnection processes.

Matteini, Lorenzo; Landi, Simone; Velli, Marco; Matthaeus, William H.

2013-06-01

230

Recovery of partial volume losses in cardiac mouse PET imaging using a combined 1D\\/2D and a combined 1D\\/3D model  

Microsoft Academic Search

Micro-PET image resolution is on the order of the left ventricle (LV) wall thickness in a mouse heart. Mouse LV images are thus subject to partial volume (PV) losses, impeding the ability to quantify tracer activity in cardiac muscle. In this study, 2D and 3D PV correction (PVC) models are proposed for mouse imaging. ECG gated PET images are acquired

Tyler Dumouchel; Robert A. de Kemp

2010-01-01

231

A preliminary work on pre-beamformed data acquisition system for ultrasound imaging with 2D transducer  

NASA Astrophysics Data System (ADS)

This paper present a preliminary work on a pre-beamformed data acquisition ultrasound imaging system for a 3-MHz, 32×32 2-D array tranducer . The row-column addressing scheme is adopted for the transducer fabrication. This scheme provides a simple interconnection, consisting of one top and one bottom single-layer flex circuits. The designed system can acquire pre-beamformed data with 12-bit resolution at 40-MHz sampling rate. The digitized data of all channels are first fed through FPGAs to deserialize and stored in a 4GB RAM buffer. The acquired data can be transferred through a 1000 Mbps Ethernet link to a computer for off-line processing and analysis. The system design is based on high-level commercial integrated circuits to obtain the maximum flexibility and minimum system complexity. Partial beam summation have been performed to help finish the 3-D B-mode volumetric imaging. Key words: ultrasound imaging system, 2-D array transducer, row-column addressing, off-line processing

Li, Xu; Song, Junjie; Wu, Qiong; Zhu, Benpeng; Jiang, Shenglin; Ding, Mingyue; Yuchi, Ming

2014-03-01

232

Biomechanical properties and microarchitecture parameters of trabecular bone are correlated with stochastic measures of 2D projection images.  

PubMed

It is well known that loss of bone mass, quantified by areal bone mineral density (aBMD) using DXA, is associated with the increasing risk of bone fractures. However, bone mineral density alone cannot fully explain changes in fracture risks. On top of bone mass, bone architecture has been identified as another key contributor to fracture risk. In this study, we used a novel stochastic approach to assess the distribution of aBMD from 2D projection images of Micro-CT scans of trabecular bone specimens at a resolution comparable to DXA images. Sill variance, a stochastic measure of distribution of aBMD, had significant relationships with microarchitecture parameters of trabecular bone, including bone volume fraction, bone surface-to-volume ratio, trabecular thickness, trabecular number, trabecular separation and anisotropy. Accordingly, it showed significantly positive correlations with strength and elastic modulus of trabecular bone. Moreover, a combination of aBMD and sill variance derived from the 2D projection images (R2=0.85) predicted bone strength better than using aBMD alone (R2=0.63). Thus, it would be promising to extend the stochastic approach to routine DXA scans to assess the distribution of aBMD, offering a more clinically significant technique for predicting risks of bone fragility fractures. PMID:23756232

Dong, Xuanliang N; Shirvaikar, Mukul; Wang, Xiaodu

2013-10-01

233

Preparation of 2D sequences of corneal images for 3D model building.  

PubMed

A confocal microscope provides a sequence of images, at incremental depths, of the various corneal layers and structures. From these, medical practioners can extract clinical information on the state of health of the patient's cornea. In this work we are addressing problems associated with capturing and processing these images including blurring, non-uniform illumination and noise, as well as the displacement of images laterally and in the anterior-posterior direction caused by subject movement. The latter may cause some of the captured images to be out of sequence in terms of depth. In this paper we introduce automated algorithms for classification, reordering, registration and segmentation to solve these problems. The successful implementation of these algorithms could open the door for another interesting development, which is the 3D modelling of these sequences. PMID:24612710

Elbita, Abdulhakim; Qahwaji, Rami; Ipson, Stanley; Sharif, Mhd Saeed; Ghanchi, Faruque

2014-04-01

234

X-ray phase-contrast imaging with 2D grating interferometry  

Microsoft Academic Search

X-ray imaging is of paramount importance for clinical and pre-clinical applications but it is fundamentally restricted by the attenuation-based contrast mechanism, which has remained essentially the same since Roentgen's discovery a century ago. Recently, based on the Talbot effect, groundbreaking work was reported using 1D gratings for x-ray phase-contrast imaging with a hospital-grade x-ray tube instead of a synchrotron or

Ming Jiang; Christopher Lee Wyatt; Ge Wang

2008-01-01

235

Registration of 2D to 3D joint images using phase-based mutual information  

NASA Astrophysics Data System (ADS)

Registration of two dimensional to three dimensional orthopaedic medical image data has important applications particularly in the area of image guided surgery and sports medicine. Fluoroscopy to computer tomography (CT) registration is an important case, wherein digitally reconstructed radiographs derived from the CT data are registered to the fluoroscopy data. Traditional registration metrics such as intensity-based mutual information (MI) typically work well but often suffer from gross misregistration errors when the image to be registered contains a partial view of the anatomy visible in the target image. Phase-based MI provides a robust alternative similarity measure which, in addition to possessing the general robustness and noise immunity that MI provides, also employs local phase information in the registration process which makes it less susceptible to the aforementioned errors. In this paper, we propose using the complex wavelet transform for computing image phase information and incorporating that into a phase-based MI measure for image registration. Tests on a CT volume and 6 fluoroscopy images of the knee are presented. The femur and the tibia in the CT volume were individually registered to the fluoroscopy images using intensity-based MI, gradient-based MI and phase-based MI. Errors in the coordinates of fiducials present in the bone structures were used to assess the accuracy of the different registration schemes. Quantitative results demonstrate that the performance of intensity-based MI was the worst. Gradient-based MI performed slightly better, while phase-based MI results were the best consistently producing the lowest errors.

Dalvi, Rupin; Abugharbieh, Rafeef; Pickering, Mark; Scarvell, Jennie; Smith, Paul

2007-03-01

236

Characteristics of active and passive 2-D holographic scanner imaging systems for the middle infrared  

NASA Astrophysics Data System (ADS)

Holographic scanners are suggested for imaging in the 8-13 micron spectral region. Advantages in refrigeration and reliability are pointed out. The narrow linewidth of received irradiance may limit passive systems to applications such as thermography, where multispectral imaging should be a useful diagnostic tool. Active systems, which do not suffer from this range limitation, offer inherent advantages with regard to resolution improvement via background discrimination and also with respect to countermeasures.

Ih, C. S.; Ledet, E.; Kopeika, N. S.

1980-06-01

237

Characteristics of active and passive 2-D holographic scanner imaging systems for the middle infrared.  

PubMed

Holographic scanners are suggested for imaging in the 8-13-Mm spectral region. Advantages in refrigeration and reliability are pointed out. The narrow linewidth of received irradiance may limit passive systems to applications such as thermography, where multispectral imaging should be a useful diagnostic tool. Active systems, which do not suffer from this range limitation, offer inherent advantages with regard to resolution improvement via background discrimination and also with respect to countermeasures. PMID:20221179

Ih, C S; Kopeika, N S; Ledet, E

1980-06-15

238

A Combined Extended Circular Image And Spatial Occupancy Approach To 2-D Contour Matching  

Microsoft Academic Search

In this paper we propose representa- tions of two-dimensional curves that capture curve orientation and spatial occupancy, and we demon- strate their use in two-dimensional contour match- ing. To explicitly represent curve orientation, we generalize the notion of extended circular image to a non-convex curve, by representing such a curve as the sequence of the extended circular images of its

Evangelos E. Milios; Timothy J. Horton

1992-01-01

239

Extracting paleoclimate signals from sediment laminae: An automated 2-D image processing method  

NASA Astrophysics Data System (ADS)

Lake sediments commonly contain laminations and the occurrence and quantitative attributes of these microstrata contain signals of their depositional environment, limnological conditions, and past climate. However, the identification and measurement of laminae and their attributes remains a largely semi-manual process that is tedious, labor intensive, but subject to human error. Here, we present a method to automatically measure and accurately extract lamina properties from sediment core images. This method is comprised of four major components: (1) image enhancement that includes noise reduction and contrast enhancement to improve signal-to-background ratio and resolution of laminae; (2) identification of 1-D laminae for a user-chosen area in an image; (3) laminae connectivity analyses on the 1-D laminae to obtain a lamina stratigraphy; and (4) extraction and retrieval of the primary and derived lamination stratigraphic data. Sediment core images from Lake Hitchcock and Lake Bosumtwi were used for algorithm development and testing. Our experiments show a complete match between laminae produced by the software and manual process for images from Lake Hitchcock. Quantitative comparisons reveal an insignificant discrepancy in the number of laminae identified automatically by the software and manually by researchers, and in over 90% of the cases the position mismatch of individual laminae is less than one pixel between the software and the manual method for the experimental images from Lake Bosumtwi.

Gan, Stoney Q.; Scholz, Christopher A.

2013-03-01

240

Characterization of 2D surface imaging of tissue optical properties using a sub-millimeter fiber optic probe  

NASA Astrophysics Data System (ADS)

Broad-band light reflectance spectroscopy (LRS) of tissue with sub-millimeter fiber optic probes in the visible and nearinfrared range has shown its utility in differentiation of tissue types, identification of cancer, and measurement of stimulus-induced physiological responses. So far, single point measurement set-up has been widely employed to determine local optical properties of tissue. However, it may often be of interest to obtain a 2D map of a surface area of a tissue under investigation, rather than a single point reading, as in case of cancer margin detection or intraoperative perfusion measurement. It is thus imperative to expand the LRS technique to multipoint measurement covering a larger surface area. Here we describe the two methods that we use to quantify the hemoglobin derivatives and scattering of tissue under investigation, and then utilize two bifurcated fiber optic probes with different fiber diameters and different source-detector separations, to demonstrate the 2D imaging capability of LRS technique. In this study, we constructed a tissue phantom, simulating tissue and blood vessel, and used 2D scanning to determine the spatial resolution and depth resolution using two different probe geometries. Our results suggest that the depth sensitivity of these probes was limited to sub-millimeter for hemoglobin derivatives, whereas scattering changes could be observed up to 2mm deep. It was also found that the lateral resolution was affected, and the scattering signal became more diffuse, as a function of depth.

Sharma, Vikrant; Liu, Hanli

2011-02-01

241

The distribution of D2/D3 receptor binding in the adolescent rhesus monkey using small animal PET imaging  

PubMed Central

PET imaging of the neuroreceptor systems in the brain has earned a prominent role in studying normal development, neuropsychiatric illness and developing targeted drugs. The dopaminergic system is of particular interest due to its role in the development of cognitive function and mood as well as its suspected involvement in neuropsychiatric illness. Nonhuman primate animal models provide a valuable resource for relating neurochemical changes to behavior. To facilitate comparison within and between primate models, we report in vivo D2/D3 binding in a large cohort of adolescent rhesus monkeys. Methods In this work, the in vivo D2/D3 dopamine receptor availability was measured in a cohort of 33 rhesus monkeys in the adolescent stage of development (3.2 – 5.3 years). Both striatal and extrastriatal D2/D3 binding were measured using [F-18]fallypride with a high resolution small animal PET scanner. The distribution volume ratio (DVR) was measured for all subjects and group comparisons of D2/D3 binding among the cohort were made based on age and sex. Because two sequential studies were acquired from a single [F-18]fallypride batch, the effect of competing (unlabeled) ligand mass was also investigated. Results Among this cohort, the rank order of regional D2/D3 receptor binding did not vary from previous studies with adult rhesus monkeys, with: putamen > caudate > ventral striatum > amygdala ~ substantia nigra > medial dorsal thalamus > lateral temporal cortex ~ frontal cortex. The DVR coefficient of variation ranged from 14% – 26%, with the greatest variance seen in the head of the caudate. There were significant sex differences in [F-18]fallypride kinetics in the pituitary gland, but this was not observed for regions within the blood-brain barrier. Furthermore, no regions in the brain showed significant sex or age related differences in DVR within this small age range. Based on a wide range of injected fallypride mass across the cohort, significant competition effects could only be detected in the substantia nigra, thalamus, and frontal cortex, and were not evident above intersubject variability in all other regions. Conclusion These data represent the first report of large cohort in vivo D2/D3 dopamine whole brain binding in the adolescent brain and will serve as a valuable comparison for understanding dopamine changes during this critical time of development and provide a framework for creating a dopaminergic biochemical atlas for the rhesus monkey.

Christian, BT; Vandehey, NT; Fox, AS; Murali, D; Oakes, TR; Converse, AK; Nickles, RJ; Shelton, SE; Davidson, RJ; Kalin, NH

2009-01-01

242

Measurement of the plasma density and electron temperature uniformities in inductively coupled plasmas using 2D real time measurement method  

NASA Astrophysics Data System (ADS)

Recently, two-dimensional (2D) wafer-type probe sensor for the measurement of spatial distribution of plasma parameters was developed based on the floating harmonic method by Chung and co-workers [1, 2]. In this study, the 2D plasma density profile and electron temperature were measured in inductively coupled plasma (ICP) with various external parameters such as RF power, gas pressure, gas mixing ratio. It was found that the plasma uniformity was significantly changed with external parameters, such as gas pressure, He gas mixing, and ICP power. These results are closely related to the electron kinetics, plasma diffusion neutral depletion and ionization process and give guide lines for plasma uniformity control method by changes in the external parameters. [4pt] [1] M. H. Lee, S. H. Jang, and C. W. Chung, J. Appl. Phys. 101, 033305 (2007).[0pt] [2] Y. C. Kim, S.H. Jang, G.H. Kim, and C. W. Chung, ``Real time two-dimensional spatial distribution measurement method of electron temperature and plasma density,'' 62nd Gaseous Electronic Conference, 2009

Kim, Young-Cheol; Kim, Yu-Sin; Oh, Se-Jin; Lee, Hyo-Chang; Chung, Chin-Wook

2011-11-01

243

Tracking contrast agents using real-time 2D photoacoustic imaging system for cardiac applications  

NASA Astrophysics Data System (ADS)

Photoacoustic (PA) imaging is a rapidly developing imaging modality that can detect optical contrast agents with high sensitivity. While detectors in PA imaging have traditionally been single element ultrasound transducers, use of array systems is desirable because they potentially provide high frame rates to capture dynamic events, such as injection and distribution of contrast in clinical applications. We present preliminary data consisting of 40 second sequences of coregistered pulse-echo (PE) and PA images acquired simultaneously in real time using a clinical ultrasonic machine. Using a 7 MHz linear array, the scanner allowed simultaneous acquisition of inphase-quadrature (IQ) data on 64 elements at a rate limited by the illumination source (Q-switched laser at 20 Hz) with spatial resolution determined to be 0.6 mm (axial) and 0.4 mm (lateral). PA images had a signal-to-noise ratio of approximately 35 dB without averaging. The sequences captured the injection and distribution of an infrared-absorbing contrast agent into a cadaver rat heart. From these data, a perfusion time constant of 0.23 s-1 was estimated. After further refinement, the system will be tested in live animals. Ultimately, an integrated system in the clinic could facilitate inexpensive molecular screening for coronary artery disease.

Olafsson, Ragnar; Montilla, Leonardo; Ingram, Pier; Witte, Russell S.

2009-02-01

244

Automatic Characterization of the Physiological Condition of the Carotid Artery in 2D Ultrasound Image Sequences Using Spatiotemporal and Spatiospectral 2D Maps.  

PubMed

A novel method for characterizing and visualizing the progression of waves along the walls of the carotid artery is presented. The new approach is noninvasive and able to simultaneously capture the spatial and the temporal propagation of wavy patterns along the walls of the carotid artery in a completely automated manner. Spatiotemporal and spatiospectral 2D maps describing these patterns (in both the spatial and the frequency domains, resp.) were generated and analyzed by visual inspection as well as automatic feature extraction and classification. Three categories of cases were considered: pathological elderly, healthy elderly, and healthy young cases. Automatic differentiation, between cases of these three categories, was achieved with a sensitivity of 97.1% and a specificity of 74.5%. Two features were proposed and computed to measure the homogeneity of the spatiospectral 2D map which presents the spectral characteristics of the carotid artery wall's wavy motion pattern which are related to the physical, mechanical (e.g., elasticity), and physiological properties and conditions along the artery. These results are promising and confirm the potential of the proposed method in providing useful information which can help in revealing the physiological condition of the cardiovascular system. PMID:24971088

Hamid Muhammed, Hamed; Azar, Jimmy C

2014-01-01

245

Automatic Characterization of the Physiological Condition of the Carotid Artery in 2D Ultrasound Image Sequences Using Spatiotemporal and Spatiospectral 2D Maps  

PubMed Central

A novel method for characterizing and visualizing the progression of waves along the walls of the carotid artery is presented. The new approach is noninvasive and able to simultaneously capture the spatial and the temporal propagation of wavy patterns along the walls of the carotid artery in a completely automated manner. Spatiotemporal and spatiospectral 2D maps describing these patterns (in both the spatial and the frequency domains, resp.) were generated and analyzed by visual inspection as well as automatic feature extraction and classification. Three categories of cases were considered: pathological elderly, healthy elderly, and healthy young cases. Automatic differentiation, between cases of these three categories, was achieved with a sensitivity of 97.1% and a specificity of 74.5%. Two features were proposed and computed to measure the homogeneity of the spatiospectral 2D map which presents the spectral characteristics of the carotid artery wall's wavy motion pattern which are related to the physical, mechanical (e.g., elasticity), and physiological properties and conditions along the artery. These results are promising and confirm the potential of the proposed method in providing useful information which can help in revealing the physiological condition of the cardiovascular system.

Hamid Muhammed, Hamed; Azar, Jimmy C.

2014-01-01

246

Uncertainty in 2D hydrodynamic models from errors in roughness parameterization based on aerial images  

NASA Astrophysics Data System (ADS)

In The Netherlands, 2D-hydrodynamic simulations are used to evaluate the effect of potential safety measures against river floods. In the investigated scenarios, the floodplains are completely inundated, thus requiring realistic representations of hydraulic roughness of floodplain vegetation. The current study aims at providing better insight into the uncertainty of flood water levels due to uncertain floodplain roughness parameterization. The study focuses on three key elements in the uncertainty of floodplain roughness: (1) classification error of the landcover map, (2), within class variation of vegetation structural characteristics, and (3) mapping scale. To assess the effect of the first error source, new realizations of ecotope maps were made based on the current floodplain ecotope map and an error matrix of the classification. For the second error source, field measurements of vegetation structure were used to obtain uncertainty ranges for each vegetation structural type. The scale error was investigated by reassigning roughness codes on a smaller spatial scale. It is shown that classification accuracy of 69% leads to an uncertainty range of predicted water levels in the order of decimeters. The other error sources are less relevant. The quantification of the uncertainty in water levels can help to make better decisions on suitable flood protection measures. Moreover, the relation between uncertain floodplain roughness and the error bands in water levels may serve as a guideline for the desired accuracy of floodplain characteristics in hydrodynamic models.

Straatsma, Menno; Huthoff, Fredrik

2011-01-01

247

Extraction and comparison of gene expression patterns from 2D RNA in situ hybridization images  

PubMed Central

Motivation: Recent advancements in high-throughput imaging have created new large datasets with tens of thousands of gene expression images. Methods for capturing these spatial and/or temporal expression patterns include in situ hybridization or fluorescent reporter constructs or tags, and results are still frequently assessed by subjective qualitative comparisons. In order to deal with available large datasets, fully automated analysis methods must be developed to properly normalize and model spatial expression patterns. Results: We have developed image segmentation and registration methods to identify and extract spatial gene expression patterns from RNA in situ hybridization experiments of Drosophila embryos. These methods allow us to normalize and extract expression information for 78 621 images from 3724 genes across six time stages. The similarity between gene expression patterns is computed using four scoring metrics: mean squared error, Haar wavelet distance, mutual information and spatial mutual information (SMI). We additionally propose a strategy to calculate the significance of the similarity between two expression images, by generating surrogate datasets with similar spatial expression patterns using a Monte Carlo swap sampler. On data from an early development time stage, we show that SMI provides the most biologically relevant metric of comparison, and that our significance testing generalizes metrics to achieve similar performance. We exemplify the application of spatial metrics on the well-known Drosophila segmentation network. Availability: A Java webstart application to register and compare patterns, as well as all source code, are available from: http://tools.genome.duke.edu/generegulation/image_analysis/insitu Contact: uwe.ohler@duke.edu Supplementary information: Supplementary data are available at Bioinformatics online.

Mace, Daniel L.; Varnado, Nicole; Zhang, Weiping; Frise, Erwin; Ohler, Uwe

2010-01-01

248

Implementation of the 2-D Wavelet Transform into FPGA for Image  

NASA Astrophysics Data System (ADS)

This paper presents a hardware system implementation of the of discrete wavelet transform algoritm in two dimensions for FPGA, using the Daubechies filter family of order 2 (db2). The decomposition algorithm of this transform is designed and simulated with the Hardware Description Language VHDL and is implemented in a programmable logic device (FPGA) XC3S1200E reference, Spartan IIIE family, by Xilinx, take advantage the parallels properties of these gives us and speeds processing that can reach them. The architecture is evaluated using images input of different sizes. This implementation is done with the aim of developing a future images encryption hardware system using wavelet transform for security information.

León, M.; Barba, L.; Vargas, L.; Torres, C. O.

2011-01-01

249

Digital imaging in radiology: Preliminary results obtained with a high spatial resolution 2D silicon detector  

SciTech Connect

Double-sided microstrip silicon crystals are being tested as detectors for X-rays in the diagnostic energy range (10-100 kcV) for digital radiography. The authors have developed an ADC and CAMAC-based acquisition system to study the imaging capabilities of a silicon [mu]strip detector with 100 and 200 [mu]m read-out pitch. They present the first images of submillimeter high contract phantoms obtained with an X-ray mammography tube operating at high flux density.

Alfano, B. (Inst. per lo Studio dei Tumori Fondazione Pascale and INFN, Napoli (Italy)); Bandettini, A.; Bertolucci, E.; Bottigli, U.; Fantacci, M.E.; Rosso, V.; Stefanini, A. (Univ. di Pisa, (Italy). Dipt. di Fisica and INFN); Bencivelli, W. (dell'Univ. and INFN, Pisa (Italy). Inst. di Patologia Medica); Conti, M.; Larobina, M.; Russo, P. (Univ. di Napoli, (Italy). Dipt. di Scienze Fisiche and INFN); Guerra, A. del; Gambaccini, M.; Marziani, M. (Univ. di Ferrara, (Italy). Dipt. di Fisica and INFN); Randaccio, P. (Univ. di Cagliari, (Italy). Inst. di Fisica Medica and INFN)

1993-08-01

250

Finite Element Methods for Active Contour Models and Balloons for 2D and 3D Images  

Microsoft Academic Search

The use of energy-minimizing curves, known as "snakes" to extract features of interest in images has been introduced by Kass, Witkin and Terzopoulos [23]. A balloon model was introduced in [12] as a way to generalize and solve some of the problems encountered with the original method. We present a 3D generalization of the balloon model as a 3D deformable

Laurent D. Cohen; Isaac Cohen

1991-01-01

251

Application of 2D tomographic imaging techniques to edge turbulence in RFX-mod  

Microsoft Academic Search

In the reversed field pinch experiment RFX-mod a gas puffing imaging diagnostic is used to investigate the turbulence of the edge plasma. The system consists of a gas puffing nozzle and 32 optical channels to measure the He I (668 nm) line emission. The lines of sight are arranged into three fans intersecting each other in an area normal to

Gianluigi Serianni; Matteo Agostini; Roberto Cavazzana; Paolo Scarin

2007-01-01

252

Image reconstruction of 2D concentration distribution of particle flow with extinction optical tomography  

NASA Astrophysics Data System (ADS)

Optical tomography, as a novel technique developed recently, has drawn more and more interest among imaging of biology tissue, astronomy and industrial process monitoring, and so on. Extinction method is one of traditional measurement for particle concentration, which can be improve a novel optical measurement with computed tomography (CT) to reconstruct image of particle concentration distribution. In this paper, the theoretical model of exctinction optical tomography was presented, the relationship between geometric structure of optical array sensors and section drawings of measured area was analyzed, and so did between the structure and spatial resolution. In experiments, 8 x 8 orthogonal array of optical sensors with two-directions projection are used for flow imaging by means of FBP, which is for capturing movement track of a glass canaliculus with arenaceous quartz inside in a section. Furthermore, image reconstructions based on optical array sensors with two-directional angles and four-directional angles are simulated numerically and some significant results can be found from the simulated results.

Li, Yang; Wang, Renhuang; Zheng, Yingna

2003-09-01

253

Single-snapshot 2D color measurement by plenoptic imaging system  

NASA Astrophysics Data System (ADS)

Plenoptic cameras enable capture of directional light ray information, thus allowing applications such as digital refocusing, depth estimation, or multiband imaging. One of the most common plenoptic camera architectures contains a microlens array at the conventional image plane and a sensor at the back focal plane of the microlens array. We leverage the multiband imaging (MBI) function of this camera and develop a single-snapshot, single-sensor high color fidelity camera. Our camera is based on a plenoptic system with XYZ filters inserted in the pupil plane of the main lens. To achieve high color measurement precision of this system, we perform an end-to-end optimization of the system model that includes light source information, object information, optical system information, plenoptic image processing and color estimation processing. Optimized system characteristics are exploited to build an XYZ plenoptic colorimetric camera prototype that achieves high color measurement precision. We describe an application of our colorimetric camera to color shading evaluation of display and show that it achieves color accuracy of ?E<0.01.

Masuda, Kensuke; Yamanaka, Yuji; Maruyama, Go; Nagai, Sho; Hirai, Hideaki; Meng, Lingfei; Tosic, Ivana

2014-03-01

254

Extracting Buildings from Aerial Images Using Hierarchical Aggregation in 2D and 3D  

Microsoft Academic Search

We propose a model-based approach to automated 3D extraction of buildings fromaerial images. We focus on a reconstruction strategy that is not restricted to a small classof buildings. Therefore, we employ a generic modeling approach which relies on the welldened combination of building part models. Building parts are classied by their roof type.

André Fischer; Thomas H. Kolbe; Felicitas Lang; Armin B. Cremers; Wolfgang Förstner; Lutz Plümer; Volker Steinhage

1998-01-01

255

Ballistic 2-D Imaging Through Scattering Walls Using an Ultrafast Optical Kerr Gate  

Microsoft Academic Search

An ultrafast optical shutter was used to image ultrasmall objects hidden behind scattering walls by a procedure that selects in time the ballistic component and rejects the scattered diffusive light. Scattering walls used in this experiment included human breast tissue, chicken breast tissue, and a water suspension of polystyrene particles with scattering coefficients up to 21.7. Submillimeter resolution was achieved

L. Wang; P. P. Ho; C. Liu; G. Zhang; R. R. Alfano

1991-01-01

256

A 2D to 3D ultrasound image registration algorithm for robotically assisted laparoscopic radical prostatectomy  

Microsoft Academic Search

Robotically assisted laparoscopic radical prostatectomy (RARP) is an effective approach to resect the diseased organ, with stereoscopic views of the targeted tissue improving the dexterity of the surgeons. However, since the laparoscopic view acquires only the surface image of the tissue, the underlying distribution of the cancer within the organ is not observed, making it difficult to make informed decisions

Mehdi Esteghamatian; Stephen E. Pautler; Charles A. McKenzie; Terry M. Peters

2011-01-01

257

Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics  

NASA Astrophysics Data System (ADS)

Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the 'heavy-duty' size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel. Combustion and soot formation are almost identical for both fuels. Ignition and early combustion were studied by imaging the natural chemiluminescence using a calibrated intensified video camera. Early soot development was investigated via luminosity imaging and simultaneous planar imaging of laser-induced incandescence (LII) and elastic scattering. The latter provide relative soot concentrations and particle size distributions. Data show that ignition occurs at multiple points across the downstream region of all the fuel jets prior to first apparent heat release well before any soot luminosity occurs. Quantitative vapor-fuel/air mixture images in the leading portion of the jet are also presented and discussed with respect to the early combustion data. The first soot occurs at random locations, and shortly thereafter, small soot particles develop throughout the cross section of the leading portion of the jet. Data indicate that this soot arises from the fuel-rich premixed burn. Then, significantly larger soot particles appear around the periphery of the jet, presumably from the initial diffusion combustion. By the end of the premixed burn, the soot has developed a distribution pattern of a higher concentration toward the front of the jet and a lower concentration upstream, with the larger-sized soot particles being generally confined to the periphery of the jet.

Dec, John E.; Espey, Christoph

258

EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative.  

PubMed

We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications. PMID:24284731

Lilliu, S; Maragliano, C; Hampton, M; Elliott, M; Stefancich, M; Chiesa, M; Dahlem, M S; Macdonald, J E

2013-01-01

259

EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative  

NASA Astrophysics Data System (ADS)

We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications.

Lilliu, S.; Maragliano, C.; Hampton, M.; Elliott, M.; Stefancich, M.; Chiesa, M.; Dahlem, M. S.; MacDonald, J. E.

2013-11-01

260

Nonrigid Point Registration for 2D Curves and 3D Surfaces and its Applications in Small Animal Imaging  

PubMed Central

A nonrigid B-spline based point-matching method (BPM) is proposed to match dense surface points. The method solves both the point correspondence and nonrigid transformation without features extraction. The registration method integrates a motion model, which combines a global transformation and a B-spline based local deformation, into a robust point-matching framework. The point correspondence and deformable transformation are estimated simultaneously by fuzzy correspondence and by a deterministic annealing technique. Prior information about global translation, rotation and scaling is incorporated into the optimization. A local B-spline motion model decreases the degrees of freedom for optimization and thus enables the registration of a larger number of feature points. The performance of the BPM method has been demonstrated and validated using synthesized 2D and 3D data, mouse MRI, and micro-CT images. The proposed B-spline point-matching method can be used to register feature point sets, 2D curves, 3D surfaces, and various image data.

Wang, Hesheng; Fei, Baowei

2013-01-01

261

Least-square NUFFT methods applied to 2-D and 3-D radially encoded MR image reconstruction.  

PubMed

Radially encoded MRI has gained increasing attention due to its motion insensitivity and reduced artifacts. However, because its samples are collected nonuniformly in the k-space, multidimensional (especially 3-D) radially sampled MRI image reconstruction is challenging. The objective of this paper is to develop a reconstruction technique in high dimensions with on-the-fly kernel calculation. It implements general multidimensional nonuniform fast Fourier transform (NUFFT) algorithms and incorporates them into a k-space image reconstruction framework. The method is then applied to reconstruct from the radially encoded k-space data, although the method is applicable to any non-Cartesian patterns. Performance comparisons are made against the conventional Kaiser-Bessel (KB) gridding method for 2-D and 3-D radially encoded computer-simulated phantoms and physically scanned phantoms. The results show that the NUFFT reconstruction method has better accuracy-efficiency tradeoff than the KB gridding method when the kernel weights are calculated on the fly. It is found that for a particular conventional kernel function, using its corresponding deapodization function as a scaling factor in the NUFFT framework has the potential to improve accuracy. In particular, when a cosine scaling factor is used, the NUFFT method is faster than KB gridding method since a closed-form solution is available and is less computationally expensive than the KB kernel (KB griding requires computation of Bessel functions). The NUFFT method has been successfully applied to 2-D and 3-D in vivo studies on small animals. PMID:19174334

Song, Jiayu; Liu, Yanhui; Gewalt, Sally L; Cofer, Gary; Johnson, G Allan; Liu, Qing Huo

2009-04-01

262

Correction of beam steering effects in 2d-laser-diagnostic measure- ments in combustion engines by image postprocessing  

Microsoft Academic Search

Laser-diagnostic imaging is a powerful tool for the investigation of combustion processes in practical applications. It often suffers from beam steering effects induced by temperature and gas den- sity gradients at windows and flame structures. We present an approach to correct beam steering by digital image analysis. In this method signal distortion caused by laser light inhomogeneities is corrected for

Joachim Gronki; Christof Schulz; Hanno Scharr

263

2D and 3D imaging of mound structures from GPR measurements in Danish and Swedish limestone quarries  

NASA Astrophysics Data System (ADS)

High-resolution 2D and 3D images of limestone mound structures are obtained from GPR measurements made in limestone quarries located in southwest Sweden and Zealand, Denmark. The centre frequency of the employed antennas is 100 MHz, and the reflected GPR signals offer a vertical resolution of about 0.5 m of the internal layering of the limestone deposits. A depth penetration of 10 m is obtained. The GPR data are collected along profiles (2D imaging) and in rectangular grids (3D imaging). The investigated mound structures are of Danian age. They formed through the growth of bryozoans just below the photic zone in a cool-water environment. The observed GPR reflectivity is caused by contrasts in the physical properties between: 1) chalk layers and flint layers; 2) erosional surfaces (e.g. hardgrounds) and the layers above and below; and 3) chalk layers of different composition, porosity and/or texture. The GPR data are processed using standard seismic processing procedures (e.g. bandpass filtering and migration). The tools included in the ProMAX processing package are used for these purposes. The flanks and the internal layers of the observed mounds often dip more than 30 degrees. Therefore, proper migration of the GPR signals is essential for obtaining trustworthy images of the detailed mound structures. The data are interpreted using the PC-based software SeisVision. We find that typical mounds have widths and lengths on the order of 50 m and heights of 5-10 m. The mound structures mapped in southwest Sweden and Denmark share many common characteristics in terms of size and spatial distribution, and the internal structures of the mounds may hold the key for interpreting the geological history (e.g. growth direction) of the mounds.

Schack von Brockdorff, A.; Nielsen, L.; Boldreel, L. O.; Overgaard, T.

2003-04-01

264

Label free biochemical 2D and 3D imaging using secondary ion mass spectrometry  

PubMed Central

Time-of-flight Secondary ion mass spectrometry (ToF-SIMS) provides a method for the detection of native and exogenous compounds in biological samples on a cellular scale. Through the development of novel ion beams the amount of molecular signal available from the sample surface has been increased. Through the introduction of polyatomic ion beams, particularly C60, ToF-SIMS can now be used to monitor molecular signals as a function of depth as the sample is eroded thus proving the ability to generate 3D molecular images. Here we describe how this new capability has led to the development of novel instrumentation for 3D molecular imaging while also highlighting the importance of sample preparation and discuss the challenges that still need to be overcome to maximise the impact of the technique.

Fletcher, John S.; Vickerman, John C.; Winograd, Nicholas

2011-01-01

265

A new computational approach to cracks quantification from 2D image analysis: Application to micro-cracks description in rocks  

NASA Astrophysics Data System (ADS)

In this paper we propose a crack quantification method based on 2D image analysis. This technique is applied to a gray level Scanning Electron Microscope (SEM) images, segmented and converted in Black and White (B/W) images using the Trainable Segmentation plugin of Fiji. Resulting images are processed using a novel Matlab script composed of three different algorithms: the separation algorithm, the filtering and quantification algorithm and the orientation one. Initially the input image is enhanced via 5 morphological processes. The resulting lattice is "cut" into single cracks using 1 pixel-wide bisector lines originated from every node. Cracks are labeled using the connected-component method, then the script computes geometrical parameters, such as width, length, area, aspect ratio and orientation. A filtering is performed using a user-defined value of aspect ratio, followed by a statistical analysis of remaining cracks. In the last part of this paper we discuss about the efficiency of this script, introducing an example of analysis of two datasets with different dimension and resolution; these analyses are performed using a notebook and a high-end professional desktop solution, in order to simulate different working environments.

Arena, Alessio; Delle Piane, Claudio; Sarout, Joel

2014-05-01

266

REAL-TIME TEXTURE ANALYSIS FOR IDENTIFYING OPTIMUM MICROBUBBLE CONCENTRATION IN 2-D ULTRASONIC PARTICLE IMAGE VELOCIMETRY  

PubMed Central

Many recent studies on ultrasonic particle image velocimetry (Echo PIV) showed that the accuracy of two-dimensional (2-D) flow velocity measured depends largely on the concentration of ultrasound contrast agents (UCAs) during imaging. This article presents a texture-based method for identifying the optimum microbubble concentration for Echo PIV measurements in real-time. The texture features, standard deviation of gray level, and contrast, energy and homogeneity of gray level co-occurrence matrix were extracted from ultrasound contrast images of rotational and pulsatile flow (10 MHz) in vitro and in vivo mouse common carotid arterial flow (40 MHz) with UCAs at various concentrations. The results showed that, at concentration of 0.8~2 × 103 bubbles/mL in vitro and 1~5 × 105 bubbles/mL in vivo, image texture features had a peak value or trough value, and velocity vectors with high accuracy can be obtained. Otherwise, poor quality velocity vectors were obtained. When the texture features were used as a feature set, the accuracy of K-nearest neighbor classifier can reach 86.4% in vitro and 87.5% in vivo, respectively. The texture-based method is shown to be able to quickly identify the optimum microbubble concentration and improve the accuracy for Echo PIV imaging.

Niu, Lili; Qian, Ming; Yan, Liang; Yu, Wentao; Jiang, Bo; Jin, Qiaofeng; Wang, Yanping; Shandas, Robin; Liu, Xin; Zheng, Hairong

2013-01-01

267

Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics  

Microsoft Academic Search

Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the 'heavy-duty' size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel.

John E. Dec; Christoph Espey

1995-01-01

268

Efficient implementation of accurate geometric transformations for 2-D and 3-D image processing.  

PubMed

This paper proposes the use of a polynomial interpolator structure (based on Horner's scheme) which is efficiently realizable in hardware, for high-quality geometric transformation of two- and three-dimensional images. Polynomial-based interpolators such as cubic B-splines and optimal interpolators of shortest support are shown to be exactly implementable in the Horner structure framework. This structure suggests a hardware/software partition which can lead to efficient implementations for multidimensional interpolation. PMID:15326848

Dooley, Saul R; Stewart, Robert W; Durrani, Tariq S; Setarehdan, S Kamal; Soraghan, John J

2004-08-01

269

Localised deformation patterning in 2D granular materials revealed by digital image correlation  

Microsoft Academic Search

Tests have been performed on an analogue two-dimensional granular material in a special laboratory apparatus that allows the\\u000a application of general stress or strain conditions. Digital image correlation of pairs of consecutive photographs taken during\\u000a the tests has enabled fields of displacement and hence strain to be determined. Thus direct observation of internal displacements\\u000a and strains has been possible for

Stephen A. Hall; David Muir Wood; Erdin Ibraim; Gioacchino Viggiani

2010-01-01

270

Inflatable Icons: Diffusion-Based Interactive Extrusion of 2D Images into 3D Models  

Microsoft Academic Search

There are many applications, such as rapid prototyping, simulations and presentations, where non-professional computer end-users could benefit from the ability to create simple 3D models. Existing tools are geared towards the creation of production quality 3D models by professional users with sufficient background, time and motivation to overcome steep learning curves. Inflatable Icons combine diffusion-based image extrusion with a number

Alexander Repenning

2005-01-01

271

Double-channel, frequency-steered acoustic transducer with 2-D imaging capabilities.  

PubMed

A frequency-steerable acoustic transducer (FSAT) is employed for imaging of damage in plates through guided wave inspection. The FSAT is a shaped array with a spatial distribution that defines a spiral in wavenumber space. Its resulting frequency-dependent directional properties allow beam steering to be performed by a single two-channel device, which can be used for the imaging of a two-dimensional half-plane. Ad hoc signal processing algorithms are developed and applied to the localization of acoustic sources and scatterers when FSAT arrays are used as part of pitch-catch and pulse-echo configurations. Localization schemes rely on the spectrogram analysis of received signals upon dispersion compensation through frequency warping and the application of the frequency-angle map characteristic of FSAT. The effectiveness of FSAT designs and associated imaging schemes are demonstrated through numerical simulations and experiments. Preliminary experimental validation is performed by forming a discrete array through the points of the measurement grid of a scanning laser Doppler vibrometer. The presented results demonstrate the frequency-dependent directionality of the spiral FSAT and suggest its application for frequency-selective acoustic sensors, for the localization of broadband acoustic events, or for the directional generation of Lamb waves for active interrogation of structural health. PMID:21768027

Baravelli, Emanuele; Senesi, Matteo; Ruzzene, Massimo; De Marchi, Luca; Speciale, Nicolò

2011-07-01

272

Optoacoustic temperature monitoring during HIFU impact on biological tissues: ex vivo study and numerical simulations of 2D temperature reconstruction  

NASA Astrophysics Data System (ADS)

Dependencies of the optoacoustic (OA) transformation efficiency on tissue temperature were obtained for the application in OA temperature monitoring during thermal therapies. Accurate measurement of the OA signal amplitude versus temperature was performed in different ex-vivo tissues in the temperature range 25°C - 80°C. The investigated tissues were selected to represent different structural components: chicken breast (skeletal muscle), porcine lard (fatty tissue) and porcine liver (richly perfused tissue). Backward mode of the OA signal detection and a narrow probe laser beam were used in the experiments to avoid the influence of changes in light scattering with tissue coagulation on the OA signal amplitude. Measurements were performed in heating and cooling regimes. Characteristic behavior of the OA signal amplitude temperature dependences in different temperature ranges were described in terms of changes in different structural components of the tissue samples. Finally, numerical simulation of the OA temperature monitoring with a linear transducers array was performed to demonstrate the possibility of real-time temperature mapping.

Nikitin, Sergey; Khokhlova, Tatiana; Pelivanov, Ivan

2012-02-01

273

2D and 3D GPR imaging of structural ceilings in historic and existing constructions  

NASA Astrophysics Data System (ADS)

GPR applications in civil engineering are to date quite diversified. With respect to civil constructions and monumental buildings, detection of voids, cavities, layering in structural elements, variation of geometry, of moisture content, of materials, areas of decay, defects, cracks have been reported in timber, concrete and masonry elements. Nonetheless, many more fields of investigation remain unexplored. This contribution gives an account of a variety of examples of structural ceilings investigation by GPR radar in reflection mode, either as 2D or 3D data acquisition and visualisation. Ceilings have a pre-eminent role in buildings as they contribute to a good structural behaviour of the construction. Primarily, the following functions can be listed for ceilings: a) they carry vertical dead and live loads on floors and distribute such loads to the vertical walls; b) they oppose to external horizontal forces such as wind loads and earthquakes helping to transfer such forces from the loaded element to the other walls; c) they contribute to create the box skeleton and behaviour of a building, connecting the different load bearing walls and reducing the slenderness and flexural instability of such walls. Therefore, knowing how ceilings are made in specific buildings is of paramount importance for architects and structural engineers. According to the type of building and age of construction, ceilings may present very different solutions and materials. Moreover, in existing constructions, ceilings may have been substituted, modified or strengthened due to material decay or to change of use of the building. These alterations may often go unrecorded in technical documentation or technical drawings may be unavailable. In many cases, the position, orientation and number of the load carrying elements in ceilings may be hidden or not be in sight, due for example to the presence of false ceilings or to technical plants. GPR radar can constitute a very useful tool for investigating with rapidity and high resolution, thin as well as very thick ceilings, in a non-destructive manner. Ceilings may be made up as masonry vaults or timber/metal/concrete beams and elements laid down in one or two directions or, again, can be made as a combination of the above. A number of cases are here presented reporting on typical features to be recognised in radargrams in order to distinguish the material and possible shape of the relevant objects with the aim of providing a first small catalogue useful to the radar user and to professionals. This abstract is of interest for COST Action TU1208.

Colla, Camilla

2014-05-01

274

Real-time conversion from a single 2D face image to a 3D text-driven emotive audio-visual avatar  

Microsoft Academic Search

In this paper, we propose a complete pipeline of efficient and low-cost techniques to construct a realistic 3D text-driven emotive audio-visual avatar from a single 2D frontal-view face image of any person on the fly. This real-time conversion is achieved through three steps. First, a personalized 3D face model is built based on the 2D face image using a fully

Hao Tang; Yuxiao Hu; Yun Fu; Mark Hasegawa-johnson; Thomas S. Huang

2008-01-01

275

Application of Compressed Sensing to 2-D Ultrasonic Propagation Imaging System data  

SciTech Connect

The Ultrasonic Propagation Imaging (UPI) System is a unique, non-contact, laser-based ultrasonic excitation and measurement system developed for structural health monitoring applications. The UPI system imparts laser-induced ultrasonic excitations at user-defined locations on a structure of interest. The response of these excitations is then measured by piezoelectric transducers. By using appropriate data reconstruction techniques, a time-evolving image of the response can be generated. A representative measurement of a plate might contain 800x800 spatial data measurement locations and each measurement location might be sampled at 500 instances in time. The result is a total of 640,000 measurement locations and 320,000,000 unique measurements. This is clearly a very large set of data to collect, store in memory and process. The value of these ultrasonic response images for structural health monitoring applications makes tackling these challenges worthwhile. Recently compressed sensing has presented itself as a candidate solution for directly collecting relevant information from sparse, high-dimensional measurements. The main idea behind compressed sensing is that by directly collecting a relatively small number of coefficients it is possible to reconstruct the original measurement. The coefficients are obtained from linear combinations of (what would have been the original direct) measurements. Often compressed sensing research is simulated by generating compressed coefficients from conventionally collected measurements. The simulation approach is necessary because the direct collection of compressed coefficients often requires compressed sensing analog front-ends that are currently not commercially available. The ability of the UPI system to make measurements at user-defined locations presents a unique capability on which compressed measurement techniques may be directly applied. The application of compressed sensing techniques on this data holds the potential to reduce the number of required measurement locations, reduce the time to make measurements, reduce the memory required to store the measurements, and possibly reduce the computational burden to classify the measurements. This work considers the appropriate selection of the signal dictionary used for signal reconstruction, and performs an evaluation of compressed sensing technique's ability to reconstruct ultrasonic images using fewer measurements than would be needed using traditional Nyquist-limited data collection techniques.

Mascarenas, David D. [Los Alamos National Laboratory; Farrar, Charles R. [Los Alamos National Laboratory; Chong, See Yenn [Engineering Institute-Korea; Lee, J.R. [Engineering Institute-Korea; Park, Gyu Hae [Los Alamos National Laboratory; Flynn, Eric B. [Los Alamos National Laboratory

2012-06-29

276

SIMS of organics—Advances in 2D and 3D imaging and future outlook  

SciTech Connect

Secondary ion mass spectrometry (SIMS) has become a powerful technique for the label-free analysis of organics from cells to electronic devices. The development of cluster ion sources has revolutionized the field, increasing the sensitivity for organics by two or three orders of magnitude and for large clusters, such as C{sub 60} and argon clusters, allowing depth profiling of organics. The latter has provided the capability to generate stunning three dimensional images with depth resolutions of around 5 nm, simply unavailable by other techniques. Current state-of-the-art allows molecular images with a spatial resolution of around 500 nm to be achieved and future developments are likely to progress into the sub-100 nm regime. This review is intended to bring those with some familiarity with SIMS up-to-date with the latest developments for organics, the fundamental principles that underpin this and define the future progress. State-of-the-art examples are showcased and signposts to more in-depth reviews about specific topics given for the specialist.

Gilmore, Ian S. [National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom)] [National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom)

2013-09-15

277

Tangential 2-D Edge Imaging for GPI and Edge/Impurity Modeling  

SciTech Connect

Nova Photonics, Inc. has a collaborative effort at the National Spherical Torus Experiment (NSTX). This collaboration, based on fast imaging of visible phenomena, has provided key insights on edge turbulence, intermittency, and edge phenomena such as edge localized modes (ELMs) and multi-faceted axisymmetric radiation from the edge (MARFE). Studies have been performed in all these areas. The edge turbulence/intermittency studies make use of the Gas Puff Imaging diagnostic developed by the Principal Investigator (Ricardo Maqueda) together with colleagues from PPPL. This effort is part of the International Tokamak Physics Activity (ITPA) edge, scrape-off layer and divertor group joint activity (DSOL-15: Inter-machine comparison of blob characteristics). The edge turbulence/blob study has been extended from the current location near the midplane of the device to the lower divertor region of NSTX. The goal of this effort was to study turbulence born blobs in the vicinity of the X-point region and their circuit closure on divertor sheaths or high density regions in the divertor. In the area of ELMs and MARFEs we have studied and characterized the mode structure and evolution of the ELM types observed in NSTX, as well as the study of the observed interaction between MARFEs and ELMs. This interaction could have substantial implications for future devices where radiative divertor regions are required to maintain detachment from the divertor plasma facing components.

Dr. Ricardo Maqueda; Dr. Fred M. Levinton

2011-12-23

278

Off-axis electron holography with a dual-lens imaging system and its usefulness in 2-D potential mapping of semiconductor devices  

Microsoft Academic Search

A variable magnification electron holography, applicable for two-dimensional (2-D) potential mapping of semiconductor devices, employing a dual-lens imaging system is described. Imaging operation consists of a virtual image formed by the objective lens (OL) and a real image formed in a fixed imaging plane by the objective minilens. Wide variations in field of view (100–900nm) and fringe spacing (0.7–6nm) were

Y. Y. Wang; M. Kawasaki; J. Bruley; M. Gribelyuk; A. Domenicucci; J. Gaudiello

2004-01-01

279

Automatic multimodal 2D/3D breast image registration using biomechanical FEM models and intensity-based optimization.  

PubMed

Due to their different physical origin, X-ray mammography and Magnetic Resonance Imaging (MRI) provide complementary diagnostic information. However, the correlation of their images is challenging due to differences in dimensionality, patient positioning and compression state of the breast. Our automated registration takes over part of the correlation task. The registration method is based on a biomechanical finite element model, which is used to simulate mammographic compression. The deformed MRI volume can be compared directly with the corresponding mammogram. The registration accuracy is determined by a number of patient-specific parameters. We optimize these parameters--e.g. breast rotation--using image similarity measures. The method was evaluated on 79 datasets from clinical routine. The mean target registration error was 13.2mm in a fully automated setting. On basis of our results, we conclude that a completely automated registration of volume images with 2D mammograms is feasible. The registration accuracy is within the clinically relevant range and thus beneficial for multimodal diagnosis. PMID:23265802

Hopp, T; Dietzel, M; Baltzer, P A; Kreisel, P; Kaiser, W A; Gemmeke, H; Ruiter, N V

2013-02-01

280

Laboratory demonstration of high-contrast imaging at inner working angles 2 ?/D and better  

NASA Astrophysics Data System (ADS)

Coronagraph technology is advancing and promises to enable direct imaging and spectral characterization of extrasolar Earth-like planets in the 2020 decade with a telescope as small as 1.5m. A small Explorer-sized telescope can also be launched in the 2010 decade capable of seeing debris disks as dim as tens of zodis and potentially a few large planets. The Phase Induced Amplitude Apodization (PIAA) coronagraph makes such aggressive performance possible, providing high throughput and high contrast close to the diffraction limit. We report on the latest results from a testbed at NASA Ames that is focused on developing and testing the PIAA coronagraph. This laboratory facility was built in 2008 and is designed to be flexible, operated in an actively thermally stabilized air environment, and to complement collaborative efforts at NASA JPL's High Contrast Imaging Testbed. For our wavefront control we are using small Micro-Electro- Mechanical-System deformable mirrors (MEMS DMs), which promise to reduce the size of the beam and overall instrument, a consideration that becomes very important for small telescopes. We describe our lab progress and results, which include (as of August 2011): the demonstration of 1.9x10-8 average raw contrast in a dark zone from 2.0 - 3.4 ?/D and of 1.2x10-6 contrast from 1.5-2.0 ?/D (in monochromatic light); the testing of the next-generation reflective PIAA mirror set built by Tinsley and designed for broadband; and finally, discuss our most important past limiting factors as well as expected future ones.

Belikov, Ruslan; Pluzhnik, Eugene; Witteborn, Fred C.; Greene, Thomas P.; Lynch, Dana H.; Zell, Peter T.; Guyon, Olivier

2011-09-01

281

Temperature-tuning of transmission spectra of 2D photonic crystals made of a semiconductor with free electrons.  

NASA Astrophysics Data System (ADS)

We have studied theoretically the electromagnetic transmittance in finite samples of InSb-based 2D photonic crystals. Due to the temperature dependence of the intrinsic carrier concentration in this semiconductor, the triangular and square arrays of parallel InSb cylinders in air - or vice versa, parallel hole cylinders in InSb - give rise to tunable transmission spectra. As the temperature increases from 200 to 300 K the mid-gap frequencies move up in frequency while the widths of the gaps diminish in agreement with the bulk band structure.[1] The wave transmittance was calculated taking into account the dispersion due to phonons, as well as free charge carriers; absorptive mechanisms due to phonons, holes and electrons were also considered. We also studied tuning of localized modes due to linear defects. The corresponding transmittance peaks reveal considerable dependence on the temperature. This work was financially supported by CONACyT, Mexico, Grant No. 41195-F. [1] P. Halevi and F. Ramos-Mendieta, Phys. Rev. Lett. 85, 1875 (2000)

Manzanares-Martinez, Jesus; Ramos-Mendieta, Felipe; Halevi, Peter

2004-03-01

282

A temperature dependent 2D-ACAR study of untwinned metallic YBa{sub 2}Cu{sub 3}O{sub 7{minus}x}  

SciTech Connect

The authors have carried out 2D-ACAR measurements in the c-axis projection on an untwinned single crystal of YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} as a function of temperature, for five temperatures ranging from 30K to 300K. These temperature dependent 2D-ACAR spectra can be approximated by a superposition of two temperature independent spectra with temperature dependent weighting factors. The authors discuss how the temperature dependence of the data can be exploited to obtain a {open_quote}background corrected{close_quote} experimental spectrum, which is found to be in remarkable accord with the corresponding band theory based predictions, including for the first time the overall amplitude of the anisotropy in the 2D-ACAR. The corrected data also show clear signatures of the ridge Fermi surface and an indication of the pillbox surface.

Smedskjaer, L.C.; Welp, U.; Fang, Y.; Bailey, K.G. [Argonne National Lab., IL (United States); Bansil, A. [Northeastern Univ., Boston, MA (United States)

1992-02-01

283

Parameters Affecting the Resolution and Accuracy of 2D Quantitative Shear Wave Images  

PubMed Central

Time-of-flight methods allow quantitative measurement of shear wave speed (SWS) from ultra-sonically tracked displacements following impulsive, acoustic radiation force excitation in tissue. In heterogeneous materials, reflections at boundaries can distort the wave shape and confound determination of the wave arrival time. The magnitude of these effects depends on the shear wavelength of the excitation, the kernel size used to calculate the SWS, and the method used to determine the wave arrival time. In this study, we perform a parametric analysis of these factors using finite element modeling of the tissue response, and simulated ultrasonic tracking. Two geometries are used, a stiff, vertical layer, and a stiff spherical inclusion, each in a uniform background. Wave arrival times are estimated using the peak displacement, peak slope of the leading edge, and cross correlation methods. Results are evaluated in terms of reconstruction accuracy, resolution, contrast, and contrast-to-noise ratio of reconstructed SWS images. Superior results are obtained using narrower excitation widths and arrival time estimators which identify the leading edge of the propagating wave. The optimal kernel size is determined by a tradeoff between improved accuracy for larger kernels at the expense of spatial resolution.

Rouze, Ned C.; Wang, Michael H.; Palmeri, Mark L.; Nightingale, Kathryn R.

2012-01-01

284

Parameters affecting the resolution and accuracy of 2-D quantitative shear wave images.  

PubMed

Time-of-flight methods allow quantitative measurement of shear wave speed (SWS) from ultrasonically tracked displacements following impulsive acoustic radiation force excitation in tissue. In heterogeneous materials, reflections at boundaries can distort the wave shape and confound determination of the wave arrival time. The magnitude of these effects depends on the shear wavelength of the excitation, the kernel size used to calculate the SWS, and the method used to determine the wave arrival time. In this study, we perform a parametric analysis of these factors using finite element modeling of the tissue response and simulated ultrasonic tracking. Two geometries are used, a stiff vertical layer and a stiff spherical inclusion, each in a uniform background. Wave arrival times are estimated using the peak displacement, peak slope of the leading edge, and cross-correlation methods. Results are evaluated in terms of reconstruction accuracy, resolution, contrast, and contrast-to-noise ratio of reconstructed SWS images. Superior results are obtained using narrower excitation widths and arrival time estimators which identify the leading edge of the propagating wave. The optimal kernel size is determined by a tradeoff between improved accuracy for larger kernels at the expense of spatial resolution. PMID:22899119

Rouze, Ned C; Wang, Michael H; Palmeri, Mark L; Nightingale, Kathryn R

2012-08-01

285

Evaluation of 2D and 3D images using eye movement, head movement, and body sway  

NASA Astrophysics Data System (ADS)

The induced motion from visual information is discussed in showing the stable and moving images with or without disparities. Experiments were conducted to measure body sway, eye movement, and head movement under plane depth visual stimuli, to clarify the effect caused by the depth information for induced motion. Several obvious points emerged from the analysis of the experimental data. The minimal visual area needed to make the body stale is about 45 degrees for the plane stimuli, and is about 22.5 degrees of 45 degrees for the depth stimuli. It was also found that there are large differences in body sway between the plane stimuli and the depth stimuli after target moving. For the moving visual stimuli without disparity, the body sway was found to depend on the visual angle, but in the other case, it was found to be independent of the visual angle. This is due to the difference in OKN values from the measurement of eye movement. The frequency of emergence and the amplitude of OKN in the depth stimuli were larger than those of OKN in the plane stimuli. It was additionally observed that the low-frequency components of body sway were equal to those of head movement in these experiments.

Ojima, Shuichi; Yano, Sumio

1995-04-01

286

Segmentation of skin lesions in 2-D and 3-D ultrasound images using a spatially coherent generalized Rayleigh mixture model.  

PubMed

This paper addresses the problem of jointly estimating the statistical distribution and segmenting lesions in multiple-tissue high-frequency skin ultrasound images. The distribution of multiple-tissue images is modeled as a spatially coherent finite mixture of heavy-tailed Rayleigh distributions. Spatial coherence inherent to biological tissues is modeled by enforcing local dependence between the mixture components. An original Bayesian algorithm combined with a Markov chain Monte Carlo method is then proposed to jointly estimate the mixture parameters and a label-vector associating each voxel to a tissue. More precisely, a hybrid Metropolis-within-Gibbs sampler is used to draw samples that are asymptotically distributed according to the posterior distribution of the Bayesian model. The Bayesian estimators of the model parameters are then computed from the generated samples. Simulation results are conducted on synthetic data to illustrate the performance of the proposed estimation strategy. The method is then successfully applied to the segmentation of in vivo skin tumors in high-frequency 2-D and 3-D ultrasound images. PMID:22434797

Pereyra, Marcelo; Dobigeon, Nicolas; Batatia, Hadj; Tourneret, Jean-Yves

2012-08-01

287

An explicit shape-constrained MRF-based contour evolution method for 2-D medical image segmentation.  

PubMed

Image segmentation is, in general, an ill-posed problem and additional constraints need to be imposed in order to achieve the desired segmentation result. While segmenting organs in medical images, which is the topic of this paper, a significant amount of prior knowledge about the shape, appearance, and location of the organs is available that can be used to constrain the solution space of the segmentation problem. Among the various types of prior information, the incorporation of prior information about shape, in particular, is very challenging. In this paper, we present an explicit shape-constrained MAP-MRF-based contour evolution method for the segmentation of organs in 2-D medical images. Specifically, we represent the segmentation contour explicitly as a chain of control points. We then cast the segmentation problem as a contour evolution problem, wherein the evolution of the contour is performed by iteratively solving a MAP-MRF labeling problem. The evolution of the contour is governed by three types of prior information, namely: (i) appearance prior, (ii) boundary-edgeness prior, and (iii) shape prior, each of which is incorporated as clique potentials into the MAP-MRF problem. We use the master-slave dual decomposition framework to solve the MAP-MRF labeling problem in each iteration. In our experiments, we demonstrate the application of the proposed method to the challenging problem of heart segmentation in non-contrast computed tomography data. PMID:24403409

Chittajallu, Deepak R; Paragios, Nikos; Kakadiaris, Ioannis A

2014-01-01

288

Hartree-Fock Solutions of 2d Interacting Tight-Binding Electrons: Mott Properties and Room Temperature Superconductivity Indications  

NASA Astrophysics Data System (ADS)

Former results for a tight-binding (TB) model of CuO planes in La2CuO4 are reinterpreted here to underline their wider implications. It is noted that physical systems being appropriately described by the TB model can exhibit the main strongly correlated electron system (SCES) properties, when they are solved in the HF approximation, by also allowing crystal symmetry breaking effects and noncollinear spin orientations of the HF orbitals. It is argued how a simple 2D square lattice system of Coulomb interacting electrons can exhibit insulator gaps and pseudogap states, and quantum phase transitions as illustrated by the mentioned former works. A discussion is also presented here indicating the possibility of attaining room temperature superconductivity, by means of a surface coating with water molecules of cleaved planes of graphite, being orthogonal to its c-axis. The possibility that 2D arrays of quantum dots can give rise to the same effect is also proposed to consideration. The analysis also furnishes theoretical insight to solve the Mott-Slater debate, at least for the La2CuO4 and TMO band structures. The idea is to apply a properly noncollinear GW scheme to the electronic structure calculation of these materials. The fact is that the GW approach can be viewed as a HF procedure in which the screening polarization is also determined. This directly indicates the possibility of predicting the assumed dielectric constant in the previous works. Thus, the results seem to identify that the main correlation properties in these materials are determined by screening. Finally, the conclusions also seem to be of help for the description of the experimental observations of metal-insulator transitions and Mott properties in atoms trapped in planar photonic lattices.

Cabo Montes de Oca, A.; March, N. H.; Cabo-Bizet, A.

2014-12-01

289

2D/3D image fusion of x-ray mammograms with speed of sound images: evaluation and visualization  

NASA Astrophysics Data System (ADS)

Breast cancer is the most common cancer among women. The established screening method to detect breast cancer is X-ray mammography. However, X-ray frequently provides poor contrast of tumors located within glandular tissue. In this case, additional modalities like MRI are used for diagnosis in clinical routine. A new imaging approach is Ultrasound Computer Tomography, generating three-dimensional speed of sound images. High speed of sound values are expected to be an indicator of cancerous structures. Therefore, the combination of speed of sound images and X-ray mammograms may benefit early breast cancer diagnosis. In previous work, we proposed a method based on Finite Elements to automatically register speed of sound images with the according mammograms. The FEM simulation overcomes the challenge that X-ray mammograms show two-dimensional projections of a deformed breast whereas speed of sound images render a three-dimensional undeformed breast in prone position. In this work, 15 datasets from a clinical study were used for further evaluation of the registration quality. The quality of the registration was measured by the displacement of the center of a lesion marked in both modalities. We found a mean displacement of 7.1 mm. For visualization, an overlay technique was developed, which displays speed of sound information directly on the mammogram. Hence, the methodology provides a good basis for multimodal diagnosis using mammograms and speed of sound images. It proposes a guidance tool for radiologists who may benefit from the combined information.

Hopp, Torsten; Bonn, Julie; Ruiter, Nicole V.; Sak, Mark; Duric, Neb

2011-03-01

290

Instantaneous 2D velocity and temperature measurements in high speed flows based on spectrally resolved molecular Rayleigh scattering  

NASA Technical Reports Server (NTRS)

A Rayleigh scattering diagnostic for high speed flows is described for the simultaneous, instantaneous measurement of gas temperature and velocity at a number (up to about one hundred) of locations in a plane illuminated by an injection-seeded, frequency doubled Nd:YAG laser. Molecular Rayleigh scattered light is collected and passed through a planar mirror Fabry-Perot interferometer. The resulting image is analyzed to determine the gas temperature and bulk velocity at each of the regions. The Cramer Rao lower bound for measurement uncertainty is calculated. Experimental data is presented for a free jet and for preliminary measurements in the Lewis 4 inch by 10 inch supersonic wind tunnel.

Seasholtz, Richard G.

1995-01-01

291

Hierarchical watershed transformation based on a-priori information for spot detection in 2D gel electrophoresis images  

NASA Astrophysics Data System (ADS)

For the spot detection in 2D electrophoresis images an approach which is based on the combination of the watershed transformation (WST) with a-priori knowledge is presented. To identify spot regions in the over segmented result of the WST two types of regions have to be found: Regions that correspond to a complete spot and regions that cover only a part of a spot. The first localization step, the gray value analysis, is based on the assumptions that spot regions have significantly higher gray values than the background and that they border on a background region. Since not all remaining regions are spot or partial spot regions, additionally a curvature analysis is done. Here the a-priori knowledge is used that regarding a gel image as a surface, the shape of a spot is obviously convex. Consequently, considering the second derivative all required spot and partial spot regions can be obtained by the regions of convex curvature. In a final merging step all partial spot regions covering one spot have to be combined to only one spot region. As merging criterion two spot characteristics are used. A spot should have an approximately elliptical shape and partial spot regions of one spot should have a local convex curvature in a small neighborhood along their boundary.

Wegner, Susan; Pleissner, Klaus-Peter; Oswald, Helmut; Fleck, Eckart

1999-05-01

292

Imaging 2D structures by the CSAMT method: application to the Pantano di S. Gregorio Magno faulted basin (Southern Italy)  

NASA Astrophysics Data System (ADS)

A controlled source audiofrequency magnetotelluric (CSAMT) survey has been undertaken in the Pantano di San Gregorio Magno faulted basin, an earthquake prone area of Southern Apennines in Italy. A dataset from 11 soundings, distributed along a nearly N-S 780 m long profile, was acquired in the basin's easternmost area, where the fewest data are available as to the faulting shallow features. A preliminary skew analysis allowed a prevailing 2D nature of the dataset to be ascertained. Then, using a single-site multi-frequency approach, Dantzig's simplex algorithm was introduced for the first time to estimate the CSAMT decomposition parameters. The simplex algorithm, freely available online, proved to be fast and efficient. By this approach, the TM and TE mode field diagrams were obtained and a N35°W ± 10° 2D strike mean direction was estimated along the profile, in substantial agreement with the fault traces within the basin. A 2D inversion of the apparent resistivity and phase curves at seven almost noise-free sites distributed along the central portion of the profile was finally elaborated, reinforced by a sensitivity analysis, which allowed the best resolved portion of the model to be imaged from the first few meters of depth down to a mean depth of 300 m b.g.l. From the inverted section, the following features have been outlined: (i) a cover layer with resistivity in the range 3-30 ? m ascribed to the Quaternary lacustrine clayey deposits filling the basin, down to an average depth of about 35 m b.g.l., underlain by a structure with resistivity over 50 ? m up to about 600 ? m, ascribed to the Mesozoic carbonate bedrock; (ii) a system of two normal faults within the carbonate basement, extending down to the maximum best resolved depth of the order of 300 m b.g.l.; (iii) two wedge-shaped domains separating the opposite blocks of the faults with resistivity ranging between 30 ? m and 50 ? m and horizontal extent of the order of some tens of metres, likely filled with lacustrine sediments and embedded fine gravels.

Troiano, Antonio; Di Giuseppe, Maria Giulia; Petrillo, Zaccaria; Patella, Domenico

2009-06-01

293

Large area selective emitters/absorbers based on 2D tantalum photonic crystals for high-temperature energy applications  

NASA Astrophysics Data System (ADS)

We report highly selective emitters based on high-aspect ratio 2D photonic crystals (PhCs) fabricated on large area (2 inch diameter) polycrystalline tantalum substrates, suitable for high-temperature operation. As an example we present an optimized design for a selective emitter with a cut-off wavelength of 2?m, matched to the bandgap of an InGaAs PV cell, achieving a predicted spectral selectivity of 56.6% at 1200K. We present a fabrication route for these tantalum PhCs, based on standard microfabrication processes including deep reactive ion etch of tantalum by an SF6 based Bosch process, achieving high-aspect ratio cavities (< 8:1). Interference lithography was used to facilitate large area fabrication, maintaining both fabrication precision and uniformity, with a cavity diameter variation of less than 2% across the substrate. The fabricated tantalum PhCs exhibit strong enhancement of the emittance at wavelengths below cut-off wavelength, approaching that of blackbody, and a steep cut-off between high and low emittance spectral regions. Moreover, detailed simulations and numerical modeling show excellent agreement with experimental results. In addition, we propose a surface protective coating, which acts as a thermal barrier coating and diffusion inhibitor, and its conformal fabrication by atomic layer deposition.

Rinnerbauer, V.; Yeng, Y. X.; Senkevich, J. J.; Joannopoulos, J. D.; Solja?i?, M.; Celanovic, I.

2013-02-01

294

Robust 3D-2D image registration: application to spine interventions and vertebral labeling in the presence of anatomical deformation.  

PubMed

We present a framework for robustly estimating registration between a 3D volume image and a 2D projection image and evaluate its precision and robustness in spine interventions for vertebral localization in the presence of anatomical deformation. The framework employs a normalized gradient information similarity metric and multi-start covariance matrix adaptation evolution strategy optimization with local-restarts, which provided improved robustness against deformation and content mismatch. The parallelized implementation allowed orders-of-magnitude acceleration in computation time and improved the robustness of registration via multi-start global optimization. Experiments involved a cadaver specimen and two CT datasets (supine and prone) and 36 C-arm fluoroscopy images acquired with the specimen in four positions (supine, prone, supine with lordosis, prone with kyphosis), three regions (thoracic, abdominal, and lumbar), and three levels of geometric magnification (1.7, 2.0, 2.4). Registration accuracy was evaluated in terms of projection distance error (PDE) between the estimated and true target points in the projection image, including 14 400 random trials (200 trials on the 72 registration scenarios) with initialization error up to ±200 mm and ±10°. The resulting median PDE was better than 0.1 mm in all cases, depending somewhat on the resolution of input CT and fluoroscopy images. The cadaver experiments illustrated the tradeoff between robustness and computation time, yielding a success rate of 99.993% in vertebral labeling (with 'success' defined as PDE <5 mm) using 1,718 664 ± 96 582 function evaluations computed in 54.0 ± 3.5 s on a mid-range GPU (nVidia, GeForce GTX690). Parameters yielding a faster search (e.g., fewer multi-starts) reduced robustness under conditions of large deformation and poor initialization (99.535% success for the same data registered in 13.1 s), but given good initialization (e.g., ±5 mm, assuming a robust initial run) the same registration could be solved with 99.993% success in 6.3 s. The ability to register CT to fluoroscopy in a manner robust to patient deformation could be valuable in applications such as radiation therapy, interventional radiology, and an assistant to target localization (e.g., vertebral labeling) in image-guided spine surgery. PMID:24246386

Otake, Yoshito; Wang, Adam S; Webster Stayman, J; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Khanna, A Jay; Gokaslan, Ziya L; Siewerdsen, Jeffrey H

2013-12-01

295

Robust 3D-2D image registration: application to spine interventions and vertebral labeling in the presence of anatomical deformation  

NASA Astrophysics Data System (ADS)

We present a framework for robustly estimating registration between a 3D volume image and a 2D projection image and evaluate its precision and robustness in spine interventions for vertebral localization in the presence of anatomical deformation. The framework employs a normalized gradient information similarity metric and multi-start covariance matrix adaptation evolution strategy optimization with local-restarts, which provided improved robustness against deformation and content mismatch. The parallelized implementation allowed orders-of-magnitude acceleration in computation time and improved the robustness of registration via multi-start global optimization. Experiments involved a cadaver specimen and two CT datasets (supine and prone) and 36 C-arm fluoroscopy images acquired with the specimen in four positions (supine, prone, supine with lordosis, prone with kyphosis), three regions (thoracic, abdominal, and lumbar), and three levels of geometric magnification (1.7, 2.0, 2.4). Registration accuracy was evaluated in terms of projection distance error (PDE) between the estimated and true target points in the projection image, including 14?400 random trials (200 trials on the 72 registration scenarios) with initialization error up to ±200 mm and ±10°. The resulting median PDE was better than 0.1 mm in all cases, depending somewhat on the resolution of input CT and fluoroscopy images. The cadaver experiments illustrated the tradeoff between robustness and computation time, yielding a success rate of 99.993% in vertebral labeling (with ‘success’ defined as PDE <5 mm) using 1,718?664 ± 96?582 function evaluations computed in 54.0 ± 3.5 s on a mid-range GPU (nVidia, GeForce GTX690). Parameters yielding a faster search (e.g., fewer multi-starts) reduced robustness under conditions of large deformation and poor initialization (99.535% success for the same data registered in 13.1 s), but given good initialization (e.g., ±5 mm, assuming a robust initial run) the same registration could be solved with 99.993% success in 6.3 s. The ability to register CT to fluoroscopy in a manner robust to patient deformation could be valuable in applications such as radiation therapy, interventional radiology, and an assistant to target localization (e.g., vertebral labeling) in image-guided spine surgery.

Otake, Yoshito; Wang, Adam S.; Webster Stayman, J.; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Khanna, A. Jay; Gokaslan, Ziya L.; Siewerdsen, Jeffrey H.

2013-12-01

296

A Novel Assessment of Various Bio-Imaging Methods for Lung Tumor Detection and Treatment by using 4-D and 2-D CT Images.  

PubMed

Lung Cancer is known as one of the most difficult cancer to cure, and the number of deaths that it causes generally increasing. A detection of the Lung Cancer in its early stage can be helpful for Medical treatment to limit the danger, but it is a challenging problem due to Cancer cell structure. Interpretation of Medical image is often difficult and time consuming, even for the experienced Physicians. The aid of image analysis Based on machine learning can make this process easier. This paper describes fully Automatic Decision Support system for Lung Cancer diagnostic from CT Lung images. Most traditional medical diagnosis systems are founded on huge quantity of training data and takes long processing time. However, on the occasion that very little volume of data is available, the traditional diagnosis systems derive defects such as larger error, Time complexity. Focused on the solution to this problem, a Medical Diagnosis System based on Hidden Markov Model (HMM) is presented. In this paper we describe a pre-processing stage involving some Noise removal techniques help to solve this problem, we preprocess an images (by Mean Error Square Filtering and Histogram analysis)obtained after scanning the Lung CT images. Secondly separate the lung areas from an image by a segmentation process (by Thresholding and region growing techniques). Finally we developed HMM for the classification of Cancer Nodule. Results are checked for 2D and 4D CT images. This automation process reduces the time complexity and increases the diagnosis confidence. PMID:23847454

Judice A, Antony; Geetha, Dr K Parimala

2013-06-01

297

A Novel Assessment of Various Bio-Imaging Methods for Lung Tumor Detection and Treatment by using 4-D and 2-D CT Images  

PubMed Central

Lung Cancer is known as one of the most difficult cancer to cure, and the number of deaths that it causes generally increasing. A detection of the Lung Cancer in its early stage can be helpful for Medical treatment to limit the danger, but it is a challenging problem due to Cancer cell structure. Interpretation of Medical image is often difficult and time consuming, even for the experienced Physicians. The aid of image analysis Based on machine learning can make this process easier. This paper describes fully Automatic Decision Support system for Lung Cancer diagnostic from CT Lung images. Most traditional medical diagnosis systems are founded on huge quantity of training data and takes long processing time. However, on the occasion that very little volume of data is available, the traditional diagnosis systems derive defects such as larger error, Time complexity. Focused on the solution to this problem, a Medical Diagnosis System based on Hidden Markov Model (HMM) is presented. In this paper we describe a pre-processing stage involving some Noise removal techniques help to solve this problem, we preprocess an images (by Mean Error Square Filtering and Histogram analysis)obtained after scanning the Lung CT images. Secondly separate the lung areas from an image by a segmentation process (by Thresholding and region growing techniques). Finally we developed HMM for the classification of Cancer Nodule. Results are checked for 2D and 4D CT images. This automation process reduces the time complexity and increases the diagnosis confidence.

Judice A., Antony; Geetha, Dr. K. Parimala

2013-01-01

298

Source/receiver depopulation potential for 1D and 2D surface wave imaging using cross-correlation methods  

NASA Astrophysics Data System (ADS)

Surface wave tomography is aimed at imaging near-surface heterogeneities of a medium. In order to get high-resolution images, one needs numerous seismic sources, to sample the area with a great number of source-receiver paths. On the other hand, the passive cross-correlation method (also called passive seismic interferometry) is a way to 'create' data, by estimating the Green's function between each pair of receivers belonging to an array, from recordings of a diffuse wavefield. One can thus produce records as if generated from virtual sources at the receiver locations that can be used for imaging. The resolution is then governed, for a large part, by the receiver array geometry, and not so much any more by the array of actual sources. We demonstrate the feasibility of surface wave imaging using this virtual source approach, in a seismic exploration context, for both homogeneous and heterogeneous cases. The homogeneous approach consists of averaging cross-correlation functions between receivers separated by the same distance, whatever their location was. This yields a seismic profile for an equivalent homogeneous medium, which can be used to measure Rayleigh-wave dispersion curves and invert for a subsurface velocity versus depth profile. In the heterogeneous approach, receiver positions are taken into account and a tomographic inversion is applied to retrieve 2D Rayleigh-wave velocity maps as a function of frequency, a first step towards a 3D velocity model inversion. Scale of the data acreage for this study is of the order of a kilometer, with frequencies ranging from 10 to ~25 Hz. The recorded wavefield is generated by active sources, but it is used in the cross-correlation process as if it was noise, with the great advantage that the source distribution is perfectly known. Results obtained from this virtual source method compare well with those obtained from the corresponding extensive active survey. As a next step, we decreased the size of the dataset used as input for the cross-correlation, and studied in which respect the resulting tomographic image deteriorated. The results suggest that the passive correlation method provides new prospectives towards a reduction of the number of sources to be used ('source depopulation') or, with reciprocity, the number of receivers in active-source seismic surveying.

Gouedard, P.; Roux, P.; Campillo, M.; Verdel, A.; Yao, H.; van der Hilst, R. D.

2009-12-01

299

High Resolution 2-D Fluoresd3nce Imaging of the Mass Boundary Layer Thickness at Free Water Surfaces  

NASA Astrophysics Data System (ADS)

A novel 2-D fluorescence imaging technique has been developed to visualize the thickness of the aqueous mass boundary layer at a free water surface. Fluorescence is stimulated by high-power LEDs and is observed from above with a low noise, high resolution and high-speed camera. The invasion of ammonia into water leads to an increase in pH (from a starting value of 4), which is visualized with the fluorescent dye pyranine. The flux of ammonia can be controlled by controlling its air side concentration. A higher flux leads to basic pH values (pH > 7) in a thicker layer at the water surface from which fluorescent light is emitted. This allows the investigation of processes affecting the transport of gases in different depths in the aqueous mass boundary layer. In this paper, the chemical system and optical components of the measurement method are presented and its applicability to a wind-wave tank experiment is demonstrated.

Kräuter, C.; Trofimova, D.; Kiefhaber, D.; Krah, N.; Jähne, B.

2014-03-01

300

A Rapid and Efficient 2D/3D Nuclear Segmentation Method for Analysis of Early Mouse Embryo and Stem Cell Image Data  

PubMed Central

Summary Segmentation is a fundamental problem that dominates the success of microscopic image analysis. In almost 25 years of cell detection software development, there is still no single piece of commercial software that works well in practice when applied to early mouse embryo or stem cell image data. To address this need, we developed MINS (modular interactive nuclear segmentation) as a MATLAB/C++-based segmentation tool tailored for counting cells and fluorescent intensity measurements of 2D and 3D image data. Our aim was to develop a tool that is accurate and efficient yet straightforward and user friendly. The MINS pipeline comprises three major cascaded modules: detection, segmentation, and cell position classification. An extensive evaluation of MINS on both 2D and 3D images, and comparison to related tools, reveals improvements in segmentation accuracy and usability. Thus, its accuracy and ease of use will allow MINS to be implemented for routine single-cell-level image analyses.

Lou, Xinghua; Kang, Minjung; Xenopoulos, Panagiotis; Munoz-Descalzo, Silvia; Hadjantonakis, Anna-Katerina

2014-01-01

301

Ground penetrating radar: 2-D and 3-D subsurface imaging of a coastal barrier spit, Long Beach, WA, USA  

NASA Astrophysics Data System (ADS)

The ability to effectively interpret and reconstruct geomorphic environments has been significantly aided by the subsurface imaging capabilities of ground penetrating radar (GPR). The GPR method, which is based on the propagation and reflection of pulsed high frequency electromagnetic energy, provides high resolution (cm to m scale) and shallow subsurface (0-60 m), near continuous profiles of many coarser-grained deposits (sediments of low electrical conductivity). This paper presents 2-D and 3-D GPR results from an experiment on a regressive modern barrier spit at Willapa Bay, WA, USA. The medium-grained sand spit is 38 km long, up to 2-3.5 km wide, and is influenced by a 3.7-m tidal range (spring) as well as high energy longshore transport and high wave energy depositional processes. The spit has a freshwater aquifer recharged by rainfall. The GPR acquisition system used for the test was a portable, digital pulseEKKO™ system with antennae frequency ranging from 25 to 200 MHz and transmitter voltages ranging from 400 to 1000 V. Step sizes and antennae separation varied depending on the test requirements. In addition, 100-MHz antennae were used for conducting antennae orientation tests and collecting a detailed grid of data (50×50 m sampled every meter). The 2-D digital profiles were processed and plotted using pulseEKKO™ software. The 3-D datasets, after initial processing, were entered into a LANDMARK™ workstation that allowed for unique 3-D perspectives of the subsurface. To provide depth, near-surface velocity measurements were calculated from common midpoint (CMP) surveys. Results from the present study demonstrate higher resolution from the 200-MHz antennae for the top 5-6 m, whereas the 25- and 50-MHz antennae show deeper penetration to >10 m. For the study site, 100-MHz antennae provided acceptable resolution, continuity of reflections, and penetration. The dip profiles show a shingle-like accretionary depositional pattern, whereas strike profiles show a horizontal and subhorizontal, nearly continuous reflection pattern. Results from the GPR experiment reveal upper shoreface reflections with dip towards the ocean at about 1-2°. The loss of signal from below a depth of 6-8 m indicates a lithofacies change because of the storm wave base. The parallel broadside and perpendicular broadside antennae orientation tests show detailed stratigraphy, continuity, and depth of penetration. The cross-polarization test exhibits reduced continuity of reflections and less depth of penetration, but dipping reflections are apparent. The grid pattern data provided a detailed view of 3-D geometry of individual reflections. High quality data were obtained, processed, and directly exported into a LANDMARK™ workstation for interpretation. The resulting interpretations of the upper shoreface beds from the test cube (50×50 m; total 2600 traces) are shown as vertical sections (slices), horizontal sections (time slices), contour maps, 3-D representations of individual beds, and an isopach map. The 3-D depositional framework allows a more detailed interpretation than widely spaced 2-D profiles.

Jol, Harry M.; Lawton, Don C.; Smith, Derald G.

2003-07-01

302

2½D visual servoing  

Microsoft Academic Search

We propose an approach to vision-based robot control, called 2½D visual servoing, which avoids the respective drawbacks of classical position-based and image-based visual servoing. Contrary to the position-based visual servoing, our scheme does not need any geometric three-dimensional model of the object. Furthermore and contrary to image-based visual servoing, our approach ensures the convergence of the control law in the

Ezio Malis; F. Chaumette; S. Boudet

1999-01-01

303

Impact of Stratospheric Aircraft on Calculations of Nitric Acid Trihydrate Cloud Surface Area Densities Using NMC Temperatures and 2D Model Constituent Distributions.  

National Technical Information Service (NTIS)

A parameterization of NAT (nitric acid trihydrate) clouds is developed for use in 2D models of the stratosphere. The parameterization uses model distributions of HNO3 and H2O to determine critical temperatures for NAT formation as a function of latitude a...

D. B. Considine A. R. Douglass

1994-01-01

304

Real-time intensity based 2D/3D registration using kV-MV image pairs for tumor motion tracking in image guided radiotherapy  

NASA Astrophysics Data System (ADS)

Intra-fractional respiratorymotion during radiotherapy is one of themain sources of uncertainty in dose application creating the need to extend themargins of the planning target volume (PTV). Real-time tumormotion tracking by 2D/3D registration using on-board kilo-voltage (kV) imaging can lead to a reduction of the PTV. One limitation of this technique when using one projection image, is the inability to resolve motion along the imaging beam axis. We present a retrospective patient study to investigate the impact of paired portal mega-voltage (MV) and kV images, on registration accuracy. We used data from eighteen patients suffering from non small cell lung cancer undergoing regular treatment at our center. For each patient we acquired a planning CT and sequences of kV and MV images during treatment. Our evaluation consisted of comparing the accuracy of motion tracking in 6 degrees-of-freedom(DOF) using the anterior-posterior (AP) kV sequence or the sequence of kV-MV image pairs. We use graphics processing unit rendering for real-time performance. Motion along cranial-caudal direction could accurately be extracted when using only the kV sequence but in AP direction we obtained large errors. When using kV-MV pairs, the average error was reduced from 3.3 mm to 1.8 mm and the motion along AP was successfully extracted. The mean registration time was of 190+/-35ms. Our evaluation shows that using kVMV image pairs leads to improved motion extraction in 6 DOF. Therefore, this approach is suitable for accurate, real-time tumor motion tracking with a conventional LINAC.

Furtado, H.; Steiner, E.; Stock, M.; Georg, D.; Birkfellner, W.

2014-03-01

305

Efficient Decoding of 2D Structured Illumination with Linear Phase Stepping in X-Ray Phase Contrast and Dark-Field Imaging  

PubMed Central

The ability to map the phase distribution and lateral coherence of an x-ray wavefront offers the potential for imaging the human body through phase contrast, without the need to deposit significant radiation energy. The classic means to achieve this goal is structured illumination, in which a periodic intensity modulation is introduced into the image, and changes in the phase distribution of the wavefront are detected as distortions of the modulation pattern. Two-dimensional periodic patterns are needed to fully characterize a transverse wavefront. Traditionally, the information in a 2D pattern is retrieved at high resolution by acquiring multiple images while shifting the pattern over a 2D matrix of positions. Here we describe a method to decode 2D periodic patterns with single-axis phase stepping, without either a loss of information or increasing the number of sampling steps. The method is created to reduce the instrumentation complexity of high-resolution 2D wavefront sensing in general. It is demonstrated with motionless electromagnetic phase stepping and a flexible processing algorithm in x-ray dark-field and phase contrast imaging.

Harmon, Katherine J.; Bennett, Eric E.; Gomella, Andrew A.; Wen, Han

2014-01-01

306

A Geophysical Investigation of Solid Waste Landfill Using 2-D Resistivity Imaging and Vertical Electrical Sounding Methods in Port Harcourt Municipality, Rivers State, Nigeria  

Microsoft Academic Search

A combined 2-D resistivity imaging and vertical electrical sounding were conducted around a solid waste landfill in Port Harcourt municipality for a hydro-geophysical assessment of the contamination of soil and groundwater. The results revealed that the surrounding soil and groundwater in these areas around the landfill have actually been contaminated to depth exceeding 31m, which is well within the groundwater

C. N. Ehirim; J. O. Ebeniro

307

Automatic localization of target vertebrae in spine surgery using fast CT-to-fluoroscopy (3D-2D) image registration  

NASA Astrophysics Data System (ADS)

Localization of target vertebrae is an essential step in minimally invasive spine surgery, with conventional methods relying on "level counting" - i.e., manual counting of vertebrae under fluoroscopy starting from readily identifiable anatomy (e.g., the sacrum). The approach requires an undesirable level of radiation, time, and is prone to counting errors due to the similar appearance of vertebrae in projection images; wrong-level surgery occurs in 1 of every ~3000 cases. This paper proposes a method to automatically localize target vertebrae in x-ray projections using 3D-2D registration between preoperative CT (in which vertebrae are preoperatively labeled) and intraoperative fluoroscopy. The registration uses an intensity-based approach with a gradient-based similarity metric and the CMA-ES algorithm for optimization. Digitally reconstructed radiographs (DRRs) and a robust similarity metric are computed on GPU to accelerate the process. Evaluation in clinical CT data included 5,000 PA and LAT projections randomly perturbed to simulate human variability in setup of mobile intraoperative C-arm. The method demonstrated 100% success for PA view (projection error: 0.42mm) and 99.8% success for LAT view (projection error: 0.37mm). Initial implementation on GPU provided automatic target localization within about 3 sec, with further improvement underway via multi-GPU. The ability to automatically label vertebrae in fluoroscopy promises to streamline surgical workflow, improve patient safety, and reduce wrong-site surgeries, especially in large patients for whom manual methods are time consuming and error prone.

Otake, Y.; Schafer, S.; Stayman, J. W.; Zbijewski, W.; Kleinszig, G.; Graumann, R.; Khanna, A. J.; Siewerdsen, J. H.

2012-02-01

308

2D segmentation of intervertebral discs and its degree of degeneration from T2-weighted magnetic resonance images  

NASA Astrophysics Data System (ADS)

Low back pain (LBP) is a disorder suffered by a large population around the world. A key factor causing this illness is Intervertebral Disc (IVD) degeneration, whose early diagnosis could help in preventing this widespread condition. Clinicians base their diagnosis on visual inspection of 2D slices of Magnetic Resonance (MR) images, which is subject to large interobserver variability. In this work, an automatic classification method is presented, which provides the Pfirrmann degree of degeneration from a mid-sagittal MR slice. The proposed method utilizes Active Contour Models, with a new geometrical energy, to achieve an initial segmentation, which is further improved using fuzzy C-means. Then, IVDs are classified according to their degree of degeneration. This classification is attained by employing Adaboost on five specific features: the mean and the variance of the probability map of the nucleus using two different approaches and the eccentricity of the fitting ellipse to the contour of the IVD. The classification method was evaluated using a cohort of 150 intervertebral discs assessed by three experts, resulting in a mean specificity (93%) and sensitivity (83%) similar to the one provided by every expert with respect to the most voted value. The segmentation accuracy was evaluated using the Dice Similarity Index (DSI) and Root Mean Square Error (RMSE) of the point-to-contour distance. The mean DSI ± 2 standard deviation was 91:7% ±5:6%, the mean RMSE was 0:82mm and the 95 percentile was 1:36mm. These results were found accurate when compared to the state-of-the-art.

Castro-Mateos, Isaac; Pozo, José Maria; Lazary, Aron; Frangi, Alejandro F.

2014-03-01

309

Faraday imaging at high temperatures  

DOEpatents

A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

Hackel, Lloyd A. (Livermore, CA); Reichert, Patrick (Hayward, CA)

1997-01-01

310

Faraday imaging at high temperatures  

DOEpatents

A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid. 3 figs.

Hackel, L.A.; Reichert, P.

1997-03-18

311

Study of center-bias in the viewing of stereoscopic image and a framework for extending 2D visual attention models to 3D  

NASA Astrophysics Data System (ADS)

Compared to the good performance that can be achieved by many 2D visual attention models, predicting salient regions of a 3D scene is still challenging. An efficient way to achieve this can be to exploit existing models designed for 2D content. However, the visual conflicts caused by binocular disparity and changes of viewing behavior in 3D viewing need to be dealt with. To cope with these, the present paper proposes a simple framework for extending 2D attention models for 3D images, well as evaluates center-bias in 3D-viewing condition. To validate the results, a database is created, which contains eye-movements of 35 subjects recorded during free viewing of eighteen 3D images and their corresponding 2D version. Fixation density maps indicate a weaker center-bias in the viewing of 3D images. Moreover, objective metric results demonstrate the efficiency of the proposed model and a large added value of center-bias when it is taken into account in computational modeling of 3D visual attention.

Wang, Junle; Perreira Da Silva, Matthieu; Le Callet, Patrick; Ricordel, Vincent

2013-03-01

312

MTF characterization in 2D and 3D for a high resolution, large field of view flat panel imager for cone beam CT  

NASA Astrophysics Data System (ADS)

The 2D and 3D modulation transfer functions (MTFs) of a custom made, large 40x30cm2 area, 600- micron CsI-TFT based flat panel imager having 127-micron pixellation, along with the micro-fiber scintillator structure, were characterized in detail using various techniques. The larger area detector yields a reconstructed FOV of 25cm diameter with an 80cm SID in CT mode. The MTFs were determined with 1x1 (intrinsic) binning. The 2D MTFs were determined using a 50.8 micron tungsten wire and a solid lead edge, and the 3D MTF was measured using a custom made phantom consisting of three nearly orthogonal 50.8 micron tungsten wires suspended in an acrylic cubic frame. The 2D projection data was reconstructed using an iterative OSC algorithm using 16 subsets and 5 iterations. As additional verification of the resolution, along with scatter, the Catphan® phantom was also imaged and reconstructed with identical parameters. The measured 2D MTF was ~4% using the wire technique and ~1% using the edge technique at the 3.94 lp/mm Nyquist cut-off frequency. The average 3D MTF measured along the wires was ~8% at the Nyquist. At 50% MTF, the resolutions were 1.2 and 2.1 lp/mm in 2D and 3D, respectively. In the Catphan® phantom, the 1.7 lp/mm bars were easily observed. Lastly, the 3D MTF measured on the three wires has an observed 5.9% RMSD, indicating that the resolution of the imaging system is uniform and spatially independent. This high performance detector is integrated into a dedicated breast SPECT-CT imaging system.

Shah, Jainil; Mann, Steve D.; Tornai, Martin P.; Richmond, Michelle; Zentai, George

2014-03-01

313

Textural analyses of carbon fiber materials by 2D-FFT of complex images obtained by high frequency eddy current imaging (HF-ECI)  

NASA Astrophysics Data System (ADS)

Carbon fiber based materials are used in many lightweight applications in aeronautical, automotive, machine and civil engineering application. By the increasing automation in the production process of CFRP laminates a manual optical inspection of each resin transfer molding (RTM) layer is not practicable. Due to the limitation to surface inspection, the quality parameters of multilayer 3 dimensional materials cannot be observed by optical systems. The Imaging Eddy- Current (EC) NDT is the only suitable inspection method for non-resin materials in the textile state that allows an inspection of surface and hidden layers in parallel. The HF-ECI method has the capability to measure layer displacements (misaligned angle orientations) and gap sizes in a multilayer carbon fiber structure. EC technique uses the variation of the electrical conductivity of carbon based materials to obtain material properties. Beside the determination of textural parameters like layer orientation and gap sizes between rovings, the detection of foreign polymer particles, fuzzy balls or visualization of undulations can be done by the method. For all of these typical parameters an imaging classification process chain based on a high resolving directional ECimaging device named EddyCus® MPECS and a 2D-FFT with adapted preprocessing algorithms are developed.

Schulze, Martin H.; Heuer, Henning

2012-03-01

314

The 2D versus 3D imaging trade-off: The impact of over- or under-estimating small throats for simulating permeability in porous media  

NASA Astrophysics Data System (ADS)

Geochemical reactions in the subsurface can alter the porosity and permeability of a porous medium through mineral precipitation and dissolution. While effects on porosity are relatively well understood, changes in permeability are more difficult to estimate. In this work, pore-network modeling is used to estimate the permeability of a porous medium using pore and throat size distributions. These distributions can be determined from 2D Scanning Electron Microscopy (SEM) images of thin sections or from 3D X-ray Computed Tomography (CT) images of small cores. Each method has unique advantages as well as unique sources of error. 3D CT imaging has the advantage of reconstructing a 3D pore network without the inherent geometry-based biases of 2D images but is limited by resolutions around 1 ?m. 2D SEM imaging has the advantage of higher resolution, and the ability to examine sub-grain scale variations in porosity and mineralogy, but is limited by the small size of the sample of pores that are quantified. A pore network model was created to estimate flow permeability in a sand-packed experimental column investigating reaction of sediments with caustic radioactive tank wastes in the context of the Hanford, WA site. Before, periodically during, and after reaction, 3D images of the porous medium in the column were produced using the X2B beam line facility at the National Synchrotron Light Source (NSLS) at Brookhaven National Lab. These images were interpreted using 3DMA-Rock to characterize the pore and throat size distributions. After completion of the experiment, the column was sectioned and imaged using 2D SEM in backscattered electron mode. The 2D images were interpreted using erosion-dilation to estimate the pore and throat size distributions. A bias correction was determined by comparison with the 3D image data. A special image processing method was developed to infer the pore space before reaction by digitally removing the precipitate. The different sets of pore property distributions were used to generate different network flow models, to examine permeability alterations due to reaction-induced changes in throat sizes. 3D CT images, limited to a resolution of approximately 4 microns, miss small throats present at grain-to-grain contacts. The higher resolution of SEM images captures small throats between grains, however grain surface roughness and other small scale features may be misinterpreted. Precise determination of throat distributions requires careful thresholding to distinguish flow-conducting throats from throats leading to pores that are really just surface roughness. Using the pore network model, the sensitivity of permeability to the throat size roughness threshold was evaluated. Permeabilities calculated from the 2D and 3D pore and throat size distributions are compared to determine the impact of the lower resolution 3D images missing small throats.

Peters, C. A.; Crandell, L. E.; Um, W.; Jones, K. W.; Lindquist, W. B.

2011-12-01

315

Preparation and properties of 2D C\\/ZrB 2SiC ultra high temperature ceramic composites  

Microsoft Academic Search

Two-dimensional C\\/ZrB2-SiC composites were fabricated by chemical vapor infiltration (CVI) process combined with slurry paste (SP) method. ZrB2 was introduced in the matrix by stacking the pasted carbon cloth with ZrB2-polycarbosilane slurry. After heat-treated at 900°C, the stacked carbon cloth preform was infiltrated SiC by CVI process to obtain 2D C\\/ZrB2-SiC composites. Mechanical properties such as flexural strength and interlaminar

Yiguang Wang; Wen Liu; Laifei Cheng; Litong Zhang

2009-01-01

316

Multi-scale line segmentation with automatic estimation of width, contrast and tangential direction in 2D and 3D medical images  

Microsoft Academic Search

A new multi-scale segmentation technique for line-like structures in 2D and 3D medical images is presented. It is based on normalized first and second derivatives and on the eigenvector analysis of the hessian matrix. Application areas are the segmentation and tracking of bloodvessels, electrodes, catheters and other line-like objects. It allows for the estimation of the local diameter, the longitudinal

Cristian Lorenz; I.-C. Carlsen; Thorsten M. Buzug; Carola Fassnacht; Jürgen Weese

1997-01-01

317

Analysis of the coefficients of generalized bilinear transformation in the design of 2-D band-pass and band-stop filters and an application in image processing  

Microsoft Academic Search

Due to rapid progress in the field of speech and image processing, there is a greater need of a digital filter which possesses variable magnitude characteristics; one such filter is proposed in this paper. The proposed 2-D band-pass and band-elimination filters are designed from a 1-D low-pass Butterworth filter by applying a low-pass to band-pass and low-pass to band-stop transformations

Karthikeyan K. Sundaram; Venkat Ramachandran

2005-01-01

318

Off-axis electron holography with a dual-lens imaging system and its usefulness in 2-D potential mapping of semiconductor devices.  

PubMed

A variable magnification electron holography, applicable for two-dimensional (2-D) potential mapping of semiconductor devices, employing a dual-lens imaging system is described. Imaging operation consists of a virtual image formed by the objective lens (OL) and a real image formed in a fixed imaging plane by the objective minilens. Wide variations in field of view (100-900 nm) and fringe spacing (0.7-6 nm) were obtained using a fixed biprism voltage by varying the total magnification of the dual OL system. The dual-lens system allows fringe width and spacing relative to the object to be varied roughly independently from the fringe contrast, resulting in enhanced resolution and sensitivity. The achievable fringe width and spacing cover the targets needed for devices in the semiconductor technology road map from the 350 to 45 nm node. Two-D potential maps for CMOS devices with 220 and 70 nm gate lengths were obtained. PMID:15450653

Wang, Y Y; Kawasaki, M; Bruley, J; Gribelyuk, M; Domenicucci, A; Gaudiello, J

2004-11-01

319

Characteristics of Spondylotic Myelopathy on 3D Driven-Equilibrium Fast Spin Echo and 2D Fast Spin Echo Magnetic Resonance Imaging: A Retrospective Cross-Sectional Study  

PubMed Central

In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

Abdulhadi, Mike A.; Perno, Joseph R.; Melhem, Elias R.; Nucifora, Paolo G. P.

2014-01-01

320

2D multi-parameter elastic seismic imaging by frequency-domain L1-norm full waveform inversion  

NASA Astrophysics Data System (ADS)

Full waveform inversion (FWI) is becoming a powerful and efficient tool to derive high-resolution quantitative models of the subsurface. In the frequency-domain, computationally efficient FWI algorithms can be designed for wide-aperture acquisition geometries by limiting inversion to few discrete frequencies. However, FWI remains an ill-posed and highly non-linear data-fitting procedure that is sensitive to noise, inaccuracies of the starting model and definition of multiparameter classes. The footprint of the noise in seismic imaging is conventionally mitigated by stacking highly redundant multifold data. However, when the data redundancy is decimated in the framework of efficient frequency-domain FWI, it is essential to assess the sensitivity of the inversion to noise. The impact of the noise in FWI, when applied to decimated data sets, has been marginally illustrated in the past and least-squares minimisation has remained the most popular approach. We investigate in this study the sensitivity of frequency-domain elastic FWI to noise for realistic onshore and offshore synthetic data sets contaminated by ambient random white noise. Four minimisation functionals are assessed in the framework of frequency domain FWI of decimated data: the classical least-square norm (L2), the least-absolute-values norm (L1), and some combinations of both (the Huber and the so-called Hybrid criteria). These functionals are implemented in a massively-parallel, 2D elastic frequency-domain FWI algorithm. A two-level hierarchical algorithm is implemented to mitigate the non-linearity of the inversion in complex environments. The first outer level consists of successive inversions of frequency groups of increasing high-frequency content. This level defines a multi-scale approach while preserving some data redundancy by means of simultaneous inversion of multiple frequencies. The second inner level used complex-valued frequencies for data preconditioning. This preconditioning controls the amount of the data involved in the inversion from the first-arrival time and allows us to mitigate the weight of the complex late arrivals during the first iterations of the inversion. We applied our FWI approach to the SEG/EAGE overthrust model and the shallow-water Valhall model which is representative of oil and gas fields in North Sea. Results show that the L1 norm provides the most reliable models for both applications, even when only few discrete frequencies are used in the inversion and outliers pollute the data. The L2 norm can provide reliable results in the presence of uniform white noise only if the data redundancy is increased by refining the frequency sampling interval in the inversion, at the expense of the computational efficiency. The Huber and the Hybrid criteria are shown to be sensitive to a threshold, which controls the transition between the L1 and L2 behaviours, and which requires tedious trial-and-error investigations for reliable estimation. We show that the L1 norm provides a robust alternative to the classical approach based on the L2 norm for the inversion of decimated data sets in the framework of efficient frequency-domain FWI.

Brossier, Romain; Operto, Stéphane; Virieux, Jean

2010-05-01

321

Failure behavior of a 2-D woven SiC fiber/SiC matrix composite at ambient and elevated temperatures  

SciTech Connect

The failure behavior of a 2D woven SiC fiber/SiC matrix composite at ambient and elevated temperatures was studied by characterizing the R-curve behavior at ambient temperature and at 1200 C using compact tension fracture mechanics specimens. A rising R-curve behavior was observed at ambient temperature caused by fiber bridging and microcracking in the crack wake. Significant toughening was also generated by microcracking in the crack front zone. The R-curve effect at ambient temperature was substantially reduced at 1200 C as a result of degradation of the Nicalon fibers. Delamination crack growth was observed at 1200 deg indicative of a weakened fiber/matrix interface. Toughening at elevated temperature appears to result from a combination of crack branching and microcracking. 6 refs.

Nair, S.V.; Wang, Yu-Lin

1992-08-01

322

A method for the retrieval of atomic oxygen density and temperature profiles from ground-based measurements of the O(+)(2D-2P) 7320 A twilight airglow  

NASA Technical Reports Server (NTRS)

This paper describes a technique for extracting thermospheric profiles of the atomic-oxygen density and temperature, using ground-based measurements of the O(+)(2D-2P) doublet at 7320 and 7330 A in the twilight airglow. In this method, a local photochemical model is used to calculate the 7320-A intensity; the method also utilizes an iterative inversion procedure based on the Levenberg-Marquardt method described by Press et al. (1986). The results demonstrate that, if the measurements are only limited by errors due to Poisson noise, the altitude profiles of neutral temperature and atomic oxygen concentration can be determined accurately using currently available spectrometers.

Fennelly, J. A.; Torr, D. G.; Richards, P. G.; Torr, M. R.; Sharp, W. E.

1991-01-01

323

SATI image processing and mesopause temperature determination  

NASA Astrophysics Data System (ADS)

The Spectral Airglow Temperature Imager (SATI) instrument registers airglow coming from an annular mesopause segment. The temperatures of various points of this segment are retrieved by sectors of the registered images containing spectral information. A stage of SATI spectrogram processing connected with deriving spectral information from images and the determination of the rotational temperature of oxygen molecules emitting at the altitude of the mesopause is considered. A "moving sector" approach for sector spectra calculation is proposed. Typical for this approach is the possibility for varying the number of calculated sector spectra from one image and the sector angle. The sector angle may be selected depending on the quality features of the images. Two versions, one based on averaging and a second - based on finding the median of the values of all pixels at equal distance from the image center are developed. The determination of a mean temperature based on a whole image mean spectrum is considered as a potential source of systematic and gross errors. A determination of the mean temperature by averaging sector temperatures is proposed. Applying criteria for evaluating the usability of sector temperatures based on azimuthal distribution of sector errors, emission intensities and backgrounds is possible. The moving sector approach is useful with the possibility for a detailed visual evaluation of the azimuthal distribution of retrieved sector variables - rotational temperature, emission rate, background and error.

Atanassov, Atanas Marinov

2012-11-01

324

Evaluation of the Performance of HYDRUS-2D in Simulating Effects of Shading and Irrigation on Soil Water Content and Temperature  

NASA Astrophysics Data System (ADS)

Citrus root systems are exposed to different thermal and hydrologic conditions as a result of tree canopy shading and undertree microirrigation. Because microsprinklers wet only part of the soil surface and are located under the tree, roots under the canopy usually receive more water than those outside the tree canopy. The combined effects of different soil temperature and water input on water redistribution under field conditions have not been fully studied in Florida sandy soils. The objective of this study was to investigate shading and irrigation effects on spatial distribution of water content and soil temperature at different soil depths. Real-time capacitance probe systems (EnviroSCAN, SENTEK, Ltd. South Australia) and thermocouples were used to monitor soil water content and temperature at depths of 0, 10, 20, 40, 80 and 150 cm. Weather parameters were monitored simultaneously at the same location. HYDRUS-2D, a two dimensional computer package for simulating movement of water, heat, and multiple solutes in variably saturated media, was used to simulate water flow and heat transport under such conditions. The predicted water contents and soil temperatures compared favorably with their corresponding observed parameters. Shading substantially influenced hydraulic and thermal regimes of the system as shown by both predicted and measured water content and soil temperature. In addition to its accuracy in simulating this system, HYDRUS-2D helped to improve the analysis of this research project.

Fares, A.; Simunek, J.; Parsons, L. R.; van Genuchten, T. M.; Wheaton, T. A.; Morgan, K. T.

2001-12-01

325

Real-time 2D-3D MR cardiac image registration during respiration using extended Kalman filter predictors  

Microsoft Academic Search

Real-time cardiac image registration is advantageous in integrating real-time (RT) images with priory and complementary images of the myocardium. Myocardial stem cell delivery and radiofrequency ablation are some cases that could benefit RT registration. Most of these applications, However, take long time and should get along with respiratory motion. On the other hand, registration is not that sharp to compensate

Mehdi Esteghamatian; Zohreh Azimifar; Perry Radau; Graham Wright

2008-01-01

326

Temperature-dependent assemblies from a 2-D triple-stranded meso-helical layer to a 3-D chain-layer metal-organic framework.  

PubMed

Two different crystal forms, namely {[Dy2(mpda)3(H2O)2]·H2O}n (1) and [Dy2(mpda)3(H2O)4]n (2), were obtained from the reaction of multidentate 2,6-dimethylpyridine-3,5-dicarboxylic acid (H2mpda) with Dy2O3 at different temperatures. Structural analysis reveals that compound 1 is a 2-D triple-stranded meso-helical layer, and 2 a 3-D chain-layer framework. The fluorescent measure shows that compound 1 is a promising luminescent probe for various metals with a remarkable “on–off” switch of emission, mainly deriving from many pairs of inversely arranged 4-aza bowl-like crown ethers distributed in the 2-D helical plane. Moreover, compound 1 presents noticeable hydrogen-sorption at medium pressure. PMID:23108243

Jin, Hong-Guang; Hong, Xu-Jia; Li, Jing; Yan, Yuan-Zhao; Liu, Yi-Ting; Xu, Shi-Hai; Cai, Yue-Peng

2012-12-21

327

A robust cell counting approach based on a normalized 2D cross-correlation scheme for in-line holographic images.  

PubMed

To achieve the important aims of identifying and marking disease progression, cell counting is crucial for various biological and medical procedures, especially in a Point-Of-Care (POC) setting. In contrast to the conventional manual method of counting cells, a software-based approach provides improved reliability, faster speeds, and greater ease of use. We present a novel software-based approach to count in-line holographic cell images using the calculation of a normalized 2D cross-correlation. This enables fast, computationally-efficient pattern matching between a set of cell library images and the test image. Our evaluation results show that the proposed system is capable of quickly counting cells whilst reliably and accurately following human counting capability. Our novel approach is 5760 times faster than manual counting and provides at least 68% improved accuracy compared to other image processing algorithms. PMID:23839256

Ra, Ho-Kyeong; Kim, Hyungseok; Yoon, Hee Jung; Son, Sang Hyuk; Park, Taejoon; Moon, Sangjun

2013-09-01

328

Image Representations of Complete Urban Surface Temperatures  

Microsoft Academic Search

Urban areas are characterized by a strongly three?dimensional structure in which vertical surfaces can comprise a significant component of the total surface area. Two?dimensional images of radiometric surface temperature obtained from remote sensors suffer from anisotropy and may provide biased representations of the actual complete urban surface temperature. In this paper, directional radiometric surface temperatures and a GIS of building

J. A. Voogt

2000-01-01

329

a Circleless "2D/3D Total STATION": a Low Cost Instrument for Surveying, Recording Point Clouds, Documentation, Image Acquisition and Visualisation  

NASA Astrophysics Data System (ADS)

Hardware and software of the universally applicable instrument - referred to as a 2D/3D total station - are described here, as well as its practical use. At its core it consists of a 3D camera - often also called a ToF camera, a pmd camera or a RIM-camera - combined with a common industrial 2D camera. The cameras are rigidly coupled with their optical axes in parallel. A new type of instrument was created mounting this 2D/3D system on a tripod in a specific way. Because of it sharing certain characteristics with a total station and a tacheometer, respectively, the new device was called a 2D/3D total station. It may effectively replace a common total station or a laser scanner in some respects. After a brief overview of the prototype's features this paper then focuses on the methodological characteristics for practical application. Its usability as a universally applicable stand-alone instrument is demonstrated for surveying, recording RGB-coloured point clouds as well as delivering images for documentation and visualisation. Because of its limited range (10m without reflector and 150 m to reflector prisms) and low range accuracy (ca. 2 cm to 3 cm) compared to present-day total stations and laser scanners, the practical usage of the 2D/3D total station is currently limited to acquisition of accidents, forensic purpuses, speleology or facility management, as well as architectural recordings with low requirements regarding accuracy. However, the author is convinced that in the near future advancements in 3D camera technology will allow this type of comparatively low cost instrument to replace the total station as well as the laser scanner in an increasing number of areas.

Scherer, M.

2013-07-01

330

In-111 chimeric negative-charged-Z2D3 PL-F(ab`){sub 2} imaging of proliferating smooth muscle cell in atherosclerotic lesions  

SciTech Connect

Metabolically active plaques have proliferating smooth muscle cells. In-111-labeled negative-charged modified Z2-D3 PL-F(ab`){sub 2} (NC-Z2D3) specific for an antigen in proliferating smooth muscle cells has been shown to accumulate in rabbit atherosclerotic plaques. The safety, biodistribution and accumulation of NC-Z2D3 were assessed in 11 patients with angiographically confirmed carotid atheromas eligible for endarterectomy. NC-Z2D3 (250 mcg) labeled with 5 mCi of In-11 was administered by slow i.v. inj.. Planar and SPECT images were obtained 4, 24, 48 and 72 hrs later. Endarterectomy was then performed and the specimens were analyzed. Focal uptake of In-111-NCZ2D3 at the site of the carotid plaques was seen at 4 hrs. Target to control ratio at 4 hrs was 2.20 {plus_minus} 0.3, 1.98 {plus_minus} 0.03 at 24 hrs, 1.60 {plus_minus} 0.2 at 48 hrs and 1.45 {plus_minus} 0.2 at 72 hrs. The pattern of uptake was frequently more extended than the stenotic regions as delineated by the angiograms. Avidin-Biotin-Peroxidase immunostaining of the specimens revealed staining of proliferating smooth muscle cells at the site of the plaque. Percent of the injected dose per gram localization in the specimens was 0.0475 {plus_minus} 0.007. Blood clearance followed a biexponential curve with a mean t{1/2} of 920 minutes. Nonspecific localization of the antibody was observed in the liver, bone-marrow and kidneys. Adverse reactions were not seen. This study demonstrates the feasibility of targeting active atherosclerotic lesions with negatively charge-modified antibody.

Carrio, I.; Pieri, P.L.; Narula, J. [and others

1996-05-01

331

Imaging of 2-D multichannel land seismic data using an iterative inversion-migration scheme, Naga Thrust and Fold Belt, Assam, India  

NASA Astrophysics Data System (ADS)

We demonstrate that imaging of 2-D multichannel land seismic data can be effectively accomplished by a combination of reflection traveltime tomography and pre-stack depth migration (PSDM); we refer to the combined process as "the unified imaging". The unified imaging comprises cyclic runs of joint reflection and direct arrival inversion and pre-stack depth migration. From one cycle to another, both the inversion and the migration provide mutual feedbacks that are guided by the geological interpretation. The unified imaging is implemented in two broad stages. The first stage is similar to the conventional imaging except that it involves a significant use of velocity model from the inversion of the direct arrivals for both datuming and stacking velocity analysis. The first stage ends with an initial interval velocity model (from the stacking velocity analysis) and a corresponding depth migrated image. The second stage updates the velocity model and the depth image from the first stage in a cyclic manner; a single cycle comprises a single run of reflection traveltime inversion followed by PSDM. Interfaces used in the inversion are interpretations of the PSDM image in the previous cycle and the velocity model used in PSDM is from the joint inversion in the current cycle. Additionally in every cycle interpreted horizons in the stacked data are inverted as zero-offset reflections for constraining the interfaces; the velocity model is maintained stationary for the zero-offset inversion. A congruency factor, j, which measures the discrepancy between interfaces from the interpretation of the PSDM image and their corresponding counterparts from the inversion of the zero-offset reflections within assigned uncertainties, is computed in every cycle. A value of unity for jindicates that images from both the inversion and the migration are equivalent; at this point the unified imaging is said to have converged and is halted. We apply the unified imaging to 2-D multichannel seismic data from the Naga Thrust and Fold Belt (NTFB), India, were several exploratory wells in the last decade targeting sub-thrust leads in the footwall have failed. This failure is speculatively due to incorrect depth images which are in turn attributed to incorrect velocity models that are developed using conventional methods. The 2-D seismic data in this study is acquired perpendicular to the trend of the NTFB where the outcropping hanging wall has a topographic culmination. The acquisition style is split-spread with 30 m shot and receiver spacing and a nominal fold of 90. The data are recorded with a sample interval of 2 ms. Overall the data have a moderate signal-to-noise ratio and a broad frequency bandwidth of 8-80 Hz. The seismic line contains the failed exploratory well in the central part. The final results from unified imaging (both the depth image and the corresponding velocity model) suggest presence of a triangle zone, which was previously undiscovered. Conventional imaging had falsely portrayed the triangle zone as structural high which was interpreted as an anticline. As a result, the exploratory well, meant to target the anticline, met with pressure changes which were neither expected nor explained. The unified imaging results not only explain the observations in the well but also reveal new leads in the region. The velocity model from unified imaging was also found to be adequate for frequency-domain full-waveform imaging of the hanging wall. Results from waveform inversion are further corroborated by the geological interpretation of the exploratory well.

Jaiswal, Priyank; Dasgupta, Rahul

2010-05-01

332

Rapid fusion of 2D x-ray fluoroscopy with 3D multislice CT for image-guided electrophysiology procedures  

NASA Astrophysics Data System (ADS)

Interventional cardiac electrophysiology (EP) procedures are typically performed under X-ray fluoroscopy for visualizing catheters and EP devices relative to other highly-attenuating structures such as the thoracic spine and ribs. These projections do not however contain information about soft-tissue anatomy and there is a recognized need for fusion of conventional fluoroscopy with pre-operatively acquired cardiac multislice computed tomography (MSCT) volumes. Rapid 2D-3D integration in this application would allow for real-time visualization of all catheters present within the thorax in relation to the cardiovascular anatomy visible in MSCT. We present a method for rapid fusion of 2D X-ray fluoroscopy with 3DMSCT that can facilitate EP mapping and interventional procedures by reducing the need for intra-operative contrast injections to visualize heart chambers and specialized systems to track catheters within the cardiovascular anatomy. We use hardware-accelerated ray-casting to compute digitally reconstructed radiographs (DRRs) from the MSCT volume and iteratively optimize the rigid-body pose of the volumetric data to maximize the similarity between the MSCT-derived DRR and the intra-operative X-ray projection data.

Zagorchev, Lyubomir; Manzke, Robert; Cury, Ricardo; Reddy, Vivek Y.; Chan, Raymond C.

2007-03-01

333

Dense optical Flow Computation for 2D and 3D images via multigrid on a parallel machine  

Microsoft Academic Search

Summary form only given. Optical flow computation is known to be a fundamental step in many applications in image processing, pattern recognition, data compression, and biomedical technology. The goal is to compute an approximation to the projection of the 3D motion field onto the imaging surface. I consider in this talk the problem of real-time computation of dense optical flow

E.-M. Kalmoun

2007-01-01

334

A flexible and robust approach for segmenting cell nuclei from 2D microscopy images using supervised learning and template matching  

PubMed Central

We describe a new supervised learning-based template matching approach for segmenting cell nuclei from microscopy images. The method uses examples selected by a user for building a statistical model which captures the texture and shape variations of the nuclear structures from a given dataset to be segmented. Segmentation of subsequent, unlabeled, images is then performed by finding the model instance that best matches (in the normalized cross correlation sense) local neighborhood in the input image. We demonstrate the application of our method to segmenting nuclei from a variety of imaging modalities, and quantitatively compare our results to several other methods. Quantitative results using both simulated and real image data show that, while certain methods may work well for certain imaging modalities, our software is able to obtain high accuracy across several imaging modalities studied. Results also demonstrate that, relative to several existing methods, the template-based method we propose presents increased robustness in the sense of better handling variations in illumination, variations in texture from different imaging modalities, providing more smooth and accurate segmentation borders, as well as handling better cluttered nuclei.

Chen, Cheng; Wang, Wei; Ozolek, John A.; Rohde, Gustavo K.

2013-01-01

335

Measurement of 2-D SpO2 Distribution in Skin Tissue by Multispectral Imaging with Depth Selectivity Control  

Microsoft Academic Search

Two-dimensional hemoglobin oxygen saturation measurement is demonstrated by using the combination technique of multispectral imaging and the polarization control. Multispectral images are acquired at the wavelength range from 500 to 680 nm to observe the wavelength-dependent diffusely reflected light from the skin tissue. For eliminating the superficially reflected light from the skin, the skin tissue is illuminated by linearly polarized

Hidenobu Arimoto

2006-01-01

336

Digital image correlation and fracture: an advanced technique for estimating stress intensity factors of 2D and 3D cracks  

Microsoft Academic Search

Digital image correlation is a measurement technique that allows one to retrieve displacement fields 'separating' two digital images of the same sample at different stages of loading. Because of its remarkable sensitivity, it is possible to not only detect cracks with sub-pixel opening, which would not be visible but also to provide accurate estimates of stress intensity factors. For this

S. Roux; J. Réthoré; F. Hild

2009-01-01

337

Selective coding with controlled quality decay for 2D and 3D images in a JPEG2000 framework  

Microsoft Academic Search

This paper presents some ideas which extend the functionality and the application fields of a spatially selective coding within a JPEG2000 framework. At first, the image quality drop between the Regions of Interest (ROI) and the background (BG) is considered. In a conventional approach, the reconstructed image quality steeply drops along the ROI boundary; however, this effect could be considered

Alberto Signoroni; Fabio Lazzaroni; Riccardo Leonardi

2003-01-01

338

Performance analysis of a 2-D-multipulse amplitude modulation scheme for data hiding and watermarking of still images  

Microsoft Academic Search

A watermarking scheme for copyright protection of still images is modeled and analyzed. In this scheme a signal following a key-dependent two-dimensional multipulse modulation is added to the image for ownership enforcement purposes. The main contribution of this paper is the introduction of an analytical point of view to the estimation of performance measurements. Two topics are covered in the

J. R. Hernandez; F. Perez-Gonzalez; J. M. Rodriguez; G. Nieto

1998-01-01

339

Left atrial deformation parameters in patients with non-alcoholic fatty liver disease: a 2D speckle tracking imaging study.  

PubMed

The presence of the metabolic syndrome is a strong predictor for the presence of NASH (non-alcoholic steatohepatitis) in patients with NAFLD (non-alcoholic fatty liver disease). In the present study, we assessed LA (left atrial) deformation parameters in patients with NAFLD using 2D-STE (speckle tracking echocardiography) and to investigate if any changes exist between subgroups of the NAFLD. A total of 55 NAFLD patients and 21 healthy controls were included in the study. The diagnosis of NAFLD was based on liver biopsy. After patients were categorized into groups according to histopathological analysis (simple steatosis, borderline NASH, definitive NASH), all patients underwent echocardiography with Doppler examination. In the 2D-STE analysis of the left atrium, LA-Res (peak LA strain during ventricular systole), LA-Pump (peak LA strain during atrial systole), LA-SR(S) (peak LA strain rate during ventricular systole), LA-SR(E) (peak LA strain rate during early diastole) and LA-SR(A) (peak LA strain rate during atrial systole) were obtained. LA-Res, LA-Pump and LA-SR(A) were lower in the NAFLD group than in the control group. LA-Res was found to be significantly lower in NAFLD subgroups compared with healthy subjects (43.9±14.2 in healthy controls compared with 31.4±8.3 with simple steatosis, 32.8±12.8 with borderline NASH and 33.8±9.0 with definitive NASH). LA-Pump was significantly lower in the NAFLD group (18.2±3.1 in healthy controls compared with 13.3±4.7 with borderline NASH and 14.4±4.7 with definitive NASH). There were significant differences in LA-SR(A) between healthy controls compared with simple steatosis and borderline NASH (-1.56±0.36 compared with 1.14±0.38 and 1.24±0.32 respectively). Correlation analysis showed significant correlation of LA-Res values with E (early diastolic peak velocity)/E(m) (early diastolic mitral annular velocity) ratio (r=-0.50, P?0.001), with LAVI (LA volume index; r=-0.45, P?0.001) and with V(p) (propagation velocity; r=0.39, P?0.001). 2D-STE-based LA deformation parameters are impaired in patients with NAFLD with normal systolic function. Although LA-Res and pump function parameters might be useful in estimating LV (left ventricular) filling pressure in the NAFLD patient group, it could not be used for differentiating the subgroups. PMID:23947743

Kocabay, Gonenc; Karabay, Can Yucel; Colak, Yasar; Oduncu, Vecih; Kalayci, Arzu; Akgun, Taylan; Guler, Ahmet; Kirma, Cevat

2014-02-01

340

Dependence of coupling of quasi 2-D MoS2 with substrates on substrate types, probed by temperature dependent Raman scattering.  

PubMed

This work reports a study on the temperature dependence of in-plane E and out-of-plane A1g Raman modes of single-layer (1L) and bi-layer (2L) MoS2 films on sapphire (epitaxial) and SiO2 (transferred) substrates as well as bulk MoS2 single crystals in a temperature range of 25-500 °C. For the films on the transferred SiO2 substrate, the in-plane E mode is only weakly affected by the substrate, whereas the out-of-plane A1g mode is strongly perturbed, showing highly nonlinear, sometimes even non-monotonic, temperature dependence on the Raman peak shift and linewidth. In contrast, for the films on the epitaxial sapphire substrate, E is affected more significantly by the substrate than A1g. This study suggests that the 2-D film-substrate coupling depends sensitively on the preparation method, and in particular on the film morphology for the transferred film. These findings are vitally important for the fundamental understanding and application of this quasi 2-D material that is expected to be supported by a substrate in most circumstances. PMID:24676020

Su, Liqin; Zhang, Yong; Yu, Yifei; Cao, Linyou

2014-05-01

341

Registration of 2D cardiac images to real-time 3D ultrasound volumes for 3D stress echocardiography  

NASA Astrophysics Data System (ADS)

Three-dimensional (3D) stress echocardiography is a novel technique for diagnosing cardiac dysfunction, by comparing wall motion of the left ventricle under different stages of stress. For quantitative comparison of this motion, it is essential to register the ultrasound data. We propose an intensity based rigid registration method to retrieve two-dimensional (2D) four-chamber (4C), two-chamber, and short-axis planes from the 3D data set acquired in the stress stage, using manually selected 2D planes in the rest stage as reference. The algorithm uses the Nelder-Mead simplex optimization to find the optimal transformation of one uniform scaling, three rotation, and three translation parameters. We compared registration using the SAD, SSD, and NCC metrics, performed on four resolution levels of a Gaussian pyramid. The registration's effectiveness was assessed by comparing the 3D positions of the registered apex and mitral valve midpoints and 4C direction with the manually selected results. The registration was tested on data from 20 patients. Best results were found using the NCC metric on data downsampled with factor two: mean registration errors were 8.1mm, 5.4mm, and 8.0° in the apex position, mitral valve position, and 4C direction respectively. The errors were close to the interobserver (7.1mm, 3.8mm, 7.4°) and intraobserver variability (5.2mm, 3.3mm, 7.0°), and better than the error before registration (9.4mm, 9.0mm, 9.9°). We demonstrated that the registration algorithm visually and quantitatively improves the alignment of rest and stress data sets, performing similar to manual alignment. This will improve automated analysis in 3D stress echocardiography.

Leung, K. Y. Esther; van Stralen, Marijn; Voormolen, Marco M.; van Burken, Gerard; Nemes, Attila; ten Cate, Folkert J.; Geleijnse, Marcel L.; de Jong, Nico; van der Steen, Antonius F. W.; Reiber, Johan H. C.; Bosch, Johan G.

2006-03-01

342

Sensor fusion of 2D and 3D data for the processing of images of dental imprints  

NASA Astrophysics Data System (ADS)

This paper presents a computer vision system for the acquisition and processing of 3-D images of wax dental imprints. The ultimate goal of the system is to measure a set of 10 orthodontic parameters that will be fed to an expert system for automatic diagnosis of occlusion problems. An approach for the acquisition of range images of both sides of the imprint is presented. Range is obtained from a shape-from-absorption technique applied to a pair of grey-level images obtained at two different wavelengths. The accuracy of the range values is improved using sensor fusion between the initial range image and a reflectance image from the pair of grey-level images. The improved range image is segmented in order to find the interstices between teeth and, following further processing, the type of each tooth on the profile. Once each tooth has been identified, its accurate location on the imprint is found using a region- growing approach and its shape is reconstructed with third degree polynomial functions. The reconstructed shape will be later used by the system to find specific features that are needed to estimate the orthodontic parameters.

Methot, Jean-Francois; Mokhtari, Marielle; Laurendeau, Denis; Poussart, Denis

1993-08-01

343

Automatic organ localizations on 3D CT images by using majority-voting of multiple 2D detections based on local binary patterns and Haar-like features  

NASA Astrophysics Data System (ADS)

This paper describes an approach to accomplish the fast and automatic localization of the different inner organ regions on 3D CT scans. The proposed approach combines object detections and the majority voting technique to achieve the robust and quick organ localization. The basic idea of proposed method is to detect a number of 2D partial appearances of a 3D target region on CT images from multiple body directions, on multiple image scales, by using multiple feature spaces, and vote all the 2D detecting results back to the 3D image space to statistically decide one 3D bounding rectangle of the target organ. Ensemble learning was used to train the multiple 2D detectors based on template matching on local binary patterns and Haar-like feature spaces. A collaborative voting was used to decide the corner coordinates of the 3D bounding rectangle of the target organ region based on the coordinate histograms from detection results in three body directions. Since the architecture of the proposed method (multiple independent detections connected to a majority voting) naturally fits the parallel computing paradigm and multi-core CPU hardware, the proposed algorithm was easy to achieve a high computational efficiently for the organ localizations on a whole body CT scan by using general-purpose computers. We applied this approach to localization of 12 kinds of major organ regions independently on 1,300 torso CT scans. In our experiments, we randomly selected 300 CT scans (with human indicated organ and tissue locations) for training, and then, applied the proposed approach with the training results to localize each of the target regions on the other 1,000 CT scans for the performance testing. The experimental results showed the possibility of the proposed approach to automatically locate different kinds of organs on the whole body CT scans.

Zhou, Xiangrong; Yamaguchi, Shoutarou; Zhou, Xinxin; Chen, Huayue; Hara, Takeshi; Yokoyama, Ryujiro; Kanematsu, Masayuki; Fujita, Hiroshi

2013-02-01

344

Source\\/receiver depopulation potential for 1D and 2D surface wave imaging using cross-correlation methods  

Microsoft Academic Search

Surface wave tomography is aimed at imaging near-surface heterogeneities of a medium. In order to get high-resolution images, one needs numerous seismic sources, to sample the area with a great number of source-receiver paths. On the other hand, the passive cross-correlation method (also called passive seismic interferometry) is a way to 'create' data, by estimating the Green's function between each

P. Gouedard; P. Roux; M. Campillo; A. Verdel; H. Yao; R. D. van der Hilst

2009-01-01

345

Communication: two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): simultaneous planar imaging and multiplex spectroscopy in a single laser shot.  

PubMed

Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15,000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm(2). PMID:23781772

Bohlin, Alexis; Kliewer, Christopher J

2013-06-14

346

Communication: Two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): Simultaneous planar imaging and multiplex spectroscopy in a single laser shot  

NASA Astrophysics Data System (ADS)

Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15 000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm2.

Bohlin, Alexis; Kliewer, Christopher J.

2013-06-01

347

Comparison of the effect of simple and complex acquisition trajectories on the 2D SPR and 3D voxelized differences for dedicated breast CT imaging  

NASA Astrophysics Data System (ADS)

The 2D scatter-to-primary (SPR) ratios and 3D voxelized difference volumes were characterized for a cone beam breast CT scanner capable of arbitrary (non-traditional) 3D trajectories. The CT system uses a 30x30cm2 flat panel imager with 197 micron pixellation and a rotating tungsten anode x-ray source with 0.3mm focal spot, with an SID of 70cm. Data were acquired for two cylindrical phantoms (12.5cm and 15cm diameter) filled with three different combinations of water and methanol yielding a range of uniform densities. Projections were acquired with two acquisition trajectories: 1) simple-circular azimuthal orbit with fixed tilt; and 2) saddle orbit following a +/-15° sinusoidal trajectory around the object. Projection data were acquired in 2x2 binned mode. Projections were scatter corrected using a beam stop array method, and the 2D SPR was measured on the projections. The scatter corrected and uncorrected data were then reconstructed individually using an iterative ordered subsets convex algorithm, and the 3D difference volumes were calculated as the absolute difference between the two. Results indicate that the 2D SPR is ~7-15% higher on projections with greatest tilt for the saddle orbit, due to the longer x-ray path length through the volume, compared to the 0° tilt projections. Additionally, the 2D SPR increases with object diameter as well as density. The 3D voxelized difference volumes are an estimate of the scatter contribution to the reconstructed attenuation coefficients on a voxel level. They help visualize minor deficiencies and artifacts in the volumes due to correction methods.

Shah, Jainil P.; Mann, Steve D.; McKinley, Randolph L.; Tornai, Martin P.

2014-03-01

348

High spatiotemporal resolution measurement of regional lung air volumes from 2D phase contrast x-ray images  

SciTech Connect

Purpose: Described herein is a new technique for measuring regional lung air volumes from two-dimensional propagation-based phase contrast x-ray (PBI) images at very high spatial and temporal resolution. Phase contrast dramatically increases lung visibility and the outlined volumetric reconstruction technique quantifies dynamic changes in respiratory function. These methods can be used for assessing pulmonary disease and injury and for optimizing mechanical ventilation techniques for preterm infants using animal models. Methods: The volumetric reconstruction combines the algorithms of temporal subtraction and single image phase retrieval (SIPR) to isolate the image of the lungs from the thoracic cage in order to measure regional lung air volumes. The SIPR algorithm was used to recover the change in projected thickness of the lungs on a pixel-by-pixel basis (pixel dimensions {approx}16.2 {mu}m). The technique has been validated using numerical simulation and compared results of measuring regional lung air volumes with and without the use of temporal subtraction for removing the thoracic cage. To test this approach, a series of PBI images of newborn rabbit pups mechanically ventilated at different frequencies was employed. Results: Regional lung air volumes measured from PBI images of newborn rabbit pups showed on average an improvement of at least 20% in 16% of pixels within the lungs in comparison to that measured without the use of temporal subtraction. The majority of pixels that showed an improvement was found to be in regions occupied by bone. Applying the volumetric technique to sequences of PBI images of newborn rabbit pups, it is shown that lung aeration at birth can be highly heterogeneous. Conclusions: This paper presents an image segmentation technique based on temporal subtraction that has successfully been used to isolate the lungs from PBI chest images, allowing the change in lung air volume to be measured over regions as small as the pixel size. Using this technique, it is possible to measure changes in regional lung volume at high spatial and temporal resolution during breathing at much lower x-ray dose than would be required using computed tomography.

Leong, Andrew F. T.; Islam, M. Sirajul; Kitchen, Marcus J. [School of Physics, Monash University, Victoria 3800 (Australia); Fouras, Andreas [Division of Biological Engineering, Monash University, Victoria 3800 (Australia); Wallace, Megan J.; Hooper, Stuart B. [Ritchie Centre and Department of Obstetrics and Gynaecology, Monash Institute of Medical Research, Monash University, Victoria 3168 (Australia)

2013-04-15

349

Ignition and early soot formation in a D.I. diesel engine using multiple 2-D imaging diagnostics.  

National Technical Information Service (NTIS)

Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the ''heavy-duty'' size class was operated at a representative medium speed (1200 rpm) op...

J. E. Dec C. Espey

1995-01-01

350

Nonrigid Registration of 2-D and 3-D Dynamic Cell Nuclei Images for Improved Classification of Subcellular Particle Motion  

Microsoft Academic Search

The observed motion of subcellular particles in fluorescence microscopy image sequences of live cells is generally a superposition of the motion and deformation of the cell and the motion of the particles. Decoupling the two types of movements to enable accurate classification of the particle motion requires the application of registration algorithms. We have developed an intensity-based approach for nonrigid

Il-Han Kim; Yi-Chun M. Chen; David L. Spector; Roland Eils; Karl Rohr

2011-01-01

351

Automatic Detection of Optic Disc from Fundus Images of ROP Infant Using 2D Circular Hough Transform  

Microsoft Academic Search

In this paper, a method of automatic detection of an Optic Disc (OD) in low-contrast infant's digital fundus images based on circular Hough transform is proposed. Number of dimensions of normal circular Hough Transforms histogram is reduced from 3 to 2 dimensions based on an approximation of OD radius. First few circles are approximated by using maximum points from Hough

Viranee Thongnuch; Bunyarit Uyyanonvara

352

The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) - a novel Imaging DOAS device for 2-D and 3-D imaging of trace gases and aerosols  

NASA Astrophysics Data System (ADS)

Many relevant processes in tropospheric chemistry take place on rather small scales (e.g. tens to hundreds of meters) but often influence areas of several square kilometer. Thus, measurements of the involved trace gases with high spatial resolution are of great scientific interest. In order to identify individual sources and sinks and ultimately to improve chemical transport models, we developed a new airborne instrument, which is based on the well established DOAS method. The Heidelberg Airborne Imaging Differential Optical Absorption Spectrometer Instrument (HAIDI) is a passive imaging DOAS spectrometer, which is capable of recording horizontal and vertical trace gas distributions with a resolution of better than 100 m. Observable species include NO2, HCHO, C2H2O2, H2O, O3, O4, SO2, IO, OClO and BrO. Here we report a technical description of the instrument including its custom build spectrographs and CCD detectors. Also first results from measurements with the new instrument are presented. These comprise spatial resolved SO2 and BrO in volcanic plumes, mapped at Mt. Etna (Sicily, Italy), NO2 emissions in the metropolitan area of Indianapolis (Indiana, USA) as well as BrO and NO2 distributions measured during arctic springtime in context of the BROMEX campaign, which was performed 2012 in Barrow (Alaska, USA).

General, S.; Pöhler, D.; Sihler, H.; Bobrowski, N.; Frieß, U.; Zielcke, J.; Horbanski, M.; Shepson, P. B.; Stirm, B. H.; Simpson, W. R.; Weber, K.; Fischer, C.; Platt, U.

2014-03-01

353

Preliminary 3D Depth Migration of a Network of 2D Seismic Lines for Fault Imaging at a Pyramid Lake, Nevada Geothermal Prospect  

NASA Astrophysics Data System (ADS)

Many of the current geothermal power plants in western Nevada are found in extensional regimes that are associated with dilational faults and fault intersections. Most of these systems are blind and require advanced seismic imaging techniques to map target faults and reduce drilling risk. Surface features including fumaroles, hot springs, or hydrothermal deposits, like travertine and tufa, are indicators of a potential geothermal resource at depth, which still require advanced seismic imaging techniques for efficient development. One of the most notable locations of tufa deposits in western Nevada is in and around Pyramid Lake. With the abundant hydrothermal venting in the area, the tufa deposits indicate a prime locations for geothermal exploration. In 2010 and previous years, we collected about 38 km of vibroseis reflection data in a network of sixteen 2D lines of various orientations off the northwest side of Pyramid Lake. Most of these lines are within an area of only 10 square km. The 2010 survey used three heavy vibrators, and recorded 6-sec records of 8-sec, 10-100 Hz linear sweeps. Source and receiver spacing varied from 17-67 m, with up to 240 channels live for maximum offsets varying from 1000-5000 m, depending on line length. Preliminary 2D processing with first-arrival velocity optimization shows strong fault-plane reflections and several sets of stratigraphic terminations against faults. We interpret three sets of faults, which appear to intersect at about 1.25 km depth. Despite the three fault sets each appearing on several lines, only the lines trending perpendicular to fault strike show direct imaging of fault-plane reflections. We hypothesize that a 3D depth migration will reveal additional direct images of the faults. We are testing this hypothesis with a 3D Kirchhoff prestack migration of the data from this dense network of 2D lines. The 3D depth migration will take full account of lateral velocity changes. This migration should directly image additional steeply dipping fault planes at this prospect. The Pyramid Lake Paiute Tribe will use this information to build 3D geologic and hydrologic models for geothermal power development.

Frary, R.; Louie, J. N.; Pullammanappallil, S.; Eisses, A.

2011-12-01

354

Ultrasonography-based 2D motion-compensated HIFU sonication integrated with reference-free MR temperature monitoring: a feasibility study ex vivo.  

PubMed

Magnetic resonance imaging (MRI) and ultrasonography have been used simultaneously in this ex vivo study for the image-guidance of high intensity focused ultrasound (HIFU) treatment in moving tissue. A ventilator-driven balloon produced periodic and non-rigid (i.e. breathing-like) motion patterns in phantoms. MR-compatible ultrasound (US) imaging enabled near real-time 2D motion tracking based on optical flow detection, while near-harmonic reference-free proton resonance frequency shift (PRFS) MR thermometry (MRT) was used to monitor the thermal buildup on line. Reference-free MRT was applied to gradient-echo echo-planar imaging phase maps acquired at the frame rate of 250 to 300 ms/slice with voxel size 1.25×1.25×5 mm(3). The MR-US simultaneous imaging was completely free of mutual interferences while minor RF interferences from the HIFU device were detected in the far field of the US images. The effective duty-cycle of the HIFU sonication was close to 100 % and no off-interval was required to temporally decouple it from the ultrasonography. The motion compensation of the HIFU sonication was achieved with an 8 Hz frame rate and sub-millimeter spatial accuracy, both for single-focus mode and for an iterated multi-foci line scan. Near harmonic reference-less PRFS MRT delivered motion-robust thermal maps perpendicular or parallel to the HIFU beam (0.7 °C precision, 0.5 °C absolute accuracy). Out-of-plane motion compensation was not addressed in this study. PMID:22517112

Auboiroux, Vincent; Petrusca, Lorena; Viallon, Magalie; Goget, Thomas; Becker, Christoph D; Salomir, Rares

2012-05-21

355

Coupling 2D/3D registration method and statistical model to perform 3D reconstruction from partial x-rays images data.  

PubMed

3D reconstructions of the spine from a frontal and sagittal radiographs is extremely challenging. The overlying features of soft tissues and air cavities interfere with image processing. It is also difficult to obtain information that is accurate enough to reconstruct complete 3D models. To overcome these problems, the proposed method efficiently combines the partial information contained in two images from a patient with a statistical 3D spine model generated from a database of scoliotic patients. The algorithm operates through two simultaneous iterating processes. The first one generates a personalized vertebra model using a 2D/3D registration process with bone boundaries extracted from radiographs, while the other one infers the position and the shape of other vertebrae from the current estimation of the registration process using a statistical 3D model. Experimental evaluations have shown good performances of the proposed approach in terms of accuracy and robustness when compared to CT-scan. PMID:19964494

Cresson, T; Chav, R; Branchaud, D; Humbert, L; Godbout, B; Aubert, B; Skalli, W; De Guise, J A

2009-01-01

356

A novel technique for single-shot energy-resolved 2D x-ray imaging of plasmas relevant for the inertial confinement fusion.  

PubMed

A novel x-ray diagnostic of laser-fusion plasmas is described, allowing 2D monochromatic images of hot, dense plasmas to be obtained in any x-ray photon energy range, over a large domain, on a single-shot basis. The device (named energy-encoded pinhole camera) is based upon the use of an array of many pinholes coupled to a large area CCD camera operating in the single-photon mode. The available x-ray spectral domain is only limited by the quantum efficiency of scientific-grade x-ray CCD cameras, thus extending from a few keV up to a few tens of keV. Spectral 2D images of the emitting plasma can be obtained at any x-ray photon energy provided that a sufficient number of photons had been collected at the desired energy. Results from recent inertial confinement fusion related experiments will be reported in order to detail the new diagnostic. PMID:23126763

Labate, L; Köster, P; Levato, T; Gizzi, L A

2012-10-01

357

A novel technique for single-shot energy-resolved 2D x-ray imaging of plasmas relevant for the inertial confinement fusion  

NASA Astrophysics Data System (ADS)

A novel x-ray diagnostic of laser-fusion plasmas is described, allowing 2D monochromatic images of hot, dense plasmas to be obtained in any x-ray photon energy range, over a large domain, on a single-shot basis. The device (named energy-encoded pinhole camera) is based upon the use of an array of many pinholes coupled to a large area CCD camera operating in the single-photon mode. The available x-ray spectral domain is only limited by the quantum efficiency of scientific-grade x-ray CCD cameras, thus extending from a few keV up to a few tens of keV. Spectral 2D images of the emitting plasma can be obtained at any x-ray photon energy provided that a sufficient number of photons had been collected at the desired energy. Results from recent inertial confinement fusion related experiments will be reported in order to detail the new diagnostic.

Labate, L.; Köster, P.; Levato, T.; Gizzi, L. A.

2012-10-01

358

A novel technique for single-shot energy-resolved 2D x-ray imaging of plasmas relevant for the inertial confinement fusion  

SciTech Connect

A novel x-ray diagnostic of laser-fusion plasmas is described, allowing 2D monochromatic images of hot, dense plasmas to be obtained in any x-ray photon energy range, over a large domain, on a single-shot basis. The device (named energy-encoded pinhole camera) is based upon the use of an array of many pinholes coupled to a large area CCD camera operating in the single-photon mode. The available x-ray spectral domain is only limited by the quantum efficiency of scientific-grade x-ray CCD cameras, thus extending from a few keV up to a few tens of keV. Spectral 2D images of the emitting plasma can be obtained at any x-ray photon energy provided that a sufficient number of photons had been collected at the desired energy. Results from recent inertial confinement fusion related experiments will be reported in order to detail the new diagnostic.

Labate, L.; Koester, P.; Levato, T.; Gizzi, L. A. [Intense Laser Irradiation Laboratory, Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche, Pisa (Italy)

2012-10-15

359

Dependence of coupling of quasi 2-D MoS2 with substrates on substrate types, probed by temperature dependent Raman scattering  

NASA Astrophysics Data System (ADS)

This work reports a study on the temperature dependence of in-plane E12g and out-of-plane A1g Raman modes of single-layer (1L) and bi-layer (2L) MoS2 films on sapphire (epitaxial) and SiO2 (transferred) substrates as well as bulk MoS2 single crystals in a temperature range of 25-500 °C. For the films on the transferred SiO2 substrate, the in-plane E12g mode is only weakly affected by the substrate, whereas the out-of-plane A1g mode is strongly perturbed, showing highly nonlinear, sometimes even non-monotonic, temperature dependence on the Raman peak shift and linewidth. In contrast, for the films on the epitaxial sapphire substrate, E12g is affected more significantly by the substrate than A1g. This study suggests that the 2-D film-substrate coupling depends sensitively on the preparation method, and in particular on the film morphology for the transferred film. These findings are vitally important for the fundamental understanding and application of this quasi 2-D material that is expected to be supported by a substrate in most circumstances.This work reports a study on the temperature dependence of in-plane E12g and out-of-plane A1g Raman modes of single-layer (1L) and bi-layer (2L) MoS2 films on sapphire (epitaxial) and SiO2 (transferred) substrates as well as bulk MoS2 single crystals in a temperature range of 25-500 °C. For the films on the transferred SiO2 substrate, the in-plane E12g mode is only weakly affected by the substrate, whereas the out-of-plane A1g mode is strongly perturbed, showing highly nonlinear, sometimes even non-monotonic, temperature dependence on the Raman peak shift and linewidth. In contrast, for the films on the epitaxial sapphire substrate, E12g is affected more significantly by the substrate than A1g. This study suggests that the 2-D film-substrate coupling depends sensitively on the preparation method, and in particular on the film morphology for the transferred film. These findings are vitally important for the fundamental understanding and application of this quasi 2-D material that is expected to be supported by a substrate in most circumstances. Electronic supplementary information (ESI) available: The temperature-dependent Raman scattering of another two mechanically exfoliated 1L MoS2 films on the SiO2/Si substrate. See DOI: 10.1039/c3nr06462j

Su, Liqin; Zhang, Yong; Yu, Yifei; Cao, Linyou

2014-04-01

360

New technique for 2D and 3D X-ray image restoration of pipes in service given a limited access for observation  

NASA Astrophysics Data System (ADS)

Regular Computer Tomography (CT) is basically a routine procedure for the reconstruction of nearly cylindrical-symmetric objects like pipes if full access around the object is available for data acquisition. But for many practical tasks as for pipe inspection, the access to the object and the applicability of complex equipment, usually used for CT, are strongly limited. On the other hand, the importance of accurate wall thickness measurements is increased to ensure the safe operation of aging pipes and constructions in different industry sectors like chemical or power engineering industry. Two different techniques respectively for 2D and 3D image restoration of the inner profile of pipes are proposed to solve the stated ill-posed problem. The presented techniques yield iterative procedures considering prior information in the reconstruction algorithms. The prior information is introduced in a general and non-preconceived form and not oriented on the unknown image features. The feasibility of the developed techniques to restore the inner pipe surface considering 5 projections within an observation angle of 90° is illustrated by using experimental data for two pipe phantoms with damaged inner surface. For this investigation both, X-ray and Gamma-ray sources together with X-ray films and imaging plates were used in the experiments. In case of the 2D restoration the object was represented by voxels while for the 3D case a triangular surface representation as used for CAD was explored. To evaluate the reconstruction errors the restored images are compared to the phantoms. The mean error of the wall thickness restoration in smooth regions is estimated to about 200 ?m which corresponds to the spatial resolution of the data used for the calculations. .

Vengrinovich, V.; Zolotarev, S.; Kuntsevich, A.; Tillack, Gerd-Rüdiger

2001-04-01

361

2D and 3D soil moisture imaging using a sensor-based platform moving inside a subsurface network of pipes  

NASA Astrophysics Data System (ADS)

In this study a prototype sensor-based platform moving inside a subsurface network of pipes with the task of monitoring the soil moisture content is presented. It comprises of a mobile platform, a modified commercial soil moisture sensor (Diviner 2000), a network of subsurface polyvinylchloride (PVC) access pipes, driving hardware and image processing software. The software allows the composition of two-dimensional (2D) or three-dimensional (3D) images with high accuracy and at a large scale. The 3D soil moisture images are created by using 2D slices for better illustration of the soil moisture variability. Three case studies of varying soil moisture content using an experimental soil tank were examined. In the first case study, the irrigation water was applied uniformly on the entire tank surface. In second and third case studies, the irrigation water was applied uniformly only on the surface of the intermediate and last part of the soil tank respectively. The processed images give a detailed description of the soil moisture distribution of a layer at 15 cm depth under the soil surface in the tank. In all case studies that have been investigated, the distribution of soil moisture was characterized by a significant variability (difference between poorly and well-drained regions) of the soil tank. A very poorly-drained region was located in the middle of the soil tank, while well-drained soil areas were located southwest and northeast. The knowledge of the spatial and temporal distribution of soil moisture is a valuable tool for proper management of crop irrigation.

Gravalos, I.; Moshou, D.; Loutridis, S.; Gialamas, Th.; Kateris, D.; Bompolas, E.; Tsiropoulos, Z.; Xyradakis, P.; Fountas, S.

2013-08-01

362

A high-throughput imaging auxanometer for roots and hypocotyls of Arabidopsis using a 2D skeletonizing algorithm.  

PubMed

Next generation phenotyping of auxin response mutants will be greatly facilitated by the ability to record rapid growth responses in roots and hypocotyls at high throughput and at high temporal resolution. As Arabidopsis seedlings are very tiny and fragile, imaging is the only adequate way for data acquisition. As camera-based systems described before have a limited throughput, we used commercial flatbed scanners to record a large number of simultaneous experiments. We developed Hansa Trace, software for automatically detecting and measuring hypocotyl segments and roots in the images. We validated this system by measuring some well-characterized growth responses to auxins, non-auxins, ATPase activators and apoplastic acidification. The method can be shared on a cooperation basis and is able to perform measurements with minimal user intervention. PMID:24617558

Fraas, Simon; Niehoff, Vera; Lüthen, Hartwig

2014-05-01

363

A novel low-cost targeting system (LCTS) based upon a high-resolution 2D imaging laser radar  

NASA Astrophysics Data System (ADS)

BAE SYSTEMS has developed a Low Cost Targeting System (LCTS) consisting of a FLIR for target detection, laser-illuminated, gated imaging for target identification, laser rangefinder and designator, GPS positioning, and auto-tracking capability within a small compact system size. This system has proven its ability to acquire targets, range and identify these targets, and designate or provide precise geo-location coordinates to these targets. The system is based upon BAE Systems proven micro-bolometer passive LWIR camera coupled with Intevac's new EBAPS camera. A dual wavelength diode pumped laser provides eyesafe ranging and target illumination, as well as designation; a custom detector module senses the return pulse for target ranging and to set the range gates for the gated camera. Intevac's camera is a CMOS based device with used selectable gate widths and can read at up to 28 frames/second when operated in VGA mode. The Transferred Electron photocathode enables high performance imaging in the SWIR band by enabling single photon detection at high quantum efficiency. Trials show that the current detectors offer complete extinction of signals outside of the gated range, thus, providing high resolution within the gated region. The images have shown high spatial resolution arising from the use of solid state focal plane array technology. Imagery has been collected in both the laboratory and the field to verify system performance during a variety of operating conditions.

Grasso, Robert J.; Odhner, Jefferson E.; Wikman, John C.; Skaluba, Fred W.; Dippel, George F.; McDaniel, Robert V.; Ferrell, David S.; Seibel, William

2005-10-01

364

Effect of radiative transfer of heat released from combustion reaction on temperature distribution: A numerical study for a 2-D system  

NASA Astrophysics Data System (ADS)

Both light and heat are produced during a chemical reaction in a combustion process, but traditionally all the energy released is taken as to be transformed into the internal energy of the combustion medium. So the temperature of the medium increases, and then the thermal radiation emitted from it increases too. Chemiluminescence is generated during a chemical reaction and independent of the temperature, and has been used widely for combustion diagnostics. It was assumed in this paper that the total energy released in a combustion reaction is divided into two parts, one part is a self-absorbed heat, and the other is a directly emitted heat. The former is absorbed immediately by the products, becomes the internal energy and then increases the temperature of the products as treated in the traditional way. The latter is emitted directly as radiation into the combustion domain and should be included in the radiation transfer equation (RTE) as a part of radiation source. For a simple, 2-D, gray, emitting absorbing, rectangular system, the numerical study showed that the temperatures in reaction zones depended on the fraction of the directly emitted energy, and the smaller the gas absorption coefficient was, the more strong the dependence appeared. Because the effect of the fraction of the directly emitted heat on the temperature distribution in the reacting zones for gas combustion is significant, it is required to conduct experimental measurements to determine the fraction of self-absorbed heat for different combustion processes.

Zhou, Huai-Chun; Ai, Yu-Hua

2006-09-01

365

A 2D/3D image analysis system to track fluorescently labeled structures in rod-shaped cells: application to measure spindle pole asymmetry during mitosis  

PubMed Central

Background The yeast Schizosaccharomyces pombe is frequently used as a model for studying the cell cycle. The cells are rod-shaped and divide by medial fission. The process of cell division, or cytokinesis, is controlled by a network of signaling proteins called the Septation Initiation Network (SIN); SIN proteins associate with the SPBs during nuclear division (mitosis). Some SIN proteins associate with both SPBs early in mitosis, and then display strongly asymmetric signal intensity at the SPBs in late mitosis, just before cytokinesis. This asymmetry is thought to be important for correct regulation of SIN signaling, and coordination of cytokinesis and mitosis. In order to study the dynamics of organelles or large protein complexes such as the spindle pole body (SPB), which have been labeled with a fluorescent protein tag in living cells, a number of the image analysis problems must be solved; the cell outline must be detected automatically, and the position and signal intensity associated with the structures of interest within the cell must be determined. Results We present a new 2D and 3D image analysis system that permits versatile and robust analysis of motile, fluorescently labeled structures in rod-shaped cells. We have designed an image analysis system that we have implemented as a user-friendly software package allowing the fast and robust image-analysis of large numbers of rod-shaped cells. We have developed new robust algorithms, which we combined with existing methodologies to facilitate fast and accurate analysis. Our software permits the detection and segmentation of rod-shaped cells in either static or dynamic (i.e. time lapse) multi-channel images. It enables tracking of two structures (for example SPBs) in two different image channels. For 2D or 3D static images, the locations of the structures are identified, and then intensity values are extracted together with several quantitative parameters, such as length, width, cell orientation, background fluorescence and the distance between the structures of interest. Furthermore, two kinds of kymographs of the tracked structures can be established, one representing the migration with respect to their relative position, the other representing their individual trajectories inside the cell. This software package, called “RodCellJ”, allowed us to analyze a large number of S. pombe cells to understand the rules that govern SIN protein asymmetry. (Continued on next page) (Continued from previous page) Conclusions “RodCellJ” is freely available to the community as a package of several ImageJ plugins to simultaneously analyze the behavior of a large number of rod-shaped cells in an extensive manner. The integration of different image-processing techniques in a single package, as well as the development of novel algorithms does not only allow to speed up the analysis with respect to the usage of existing tools, but also accounts for higher accuracy. Its utility was demonstrated on both 2D and 3D static and dynamic images to study the septation initiation network of the yeast Schizosaccharomyces pombe. More generally, it can be used in any kind of biological context where fluorescent-protein labeled structures need to be analyzed in rod-shaped cells. Availability RodCellJ is freely available under http://bigwww.epfl.ch/algorithms.html.

2013-01-01

366

2-D PSTD Simulation of the time-reversed ultrasound-encoded deep-tissue imaging technique  

PubMed Central

We present a robust simulation technique to model the time-reversed ultrasonically encoded (TRUE) technique for deep-tissue imaging. The pseudospectral time-domain (PSTD) algorithm is employed to rigorously model the electromagnetic wave interaction of light propagating through a macroscopic scattering medium. Based upon numerical solutions of Maxwell’s equations, the amplitude and phase are accurately accounted for to analyze factors that affect the TRUE propagation of light through scattering media. More generally, we demonstrate the feasibility of modeling light propagation through a virtual tissue model of macroscopic dimensions with numerical solutions of Maxwell’s equations.

Tseng, Snow H.; Ting, Wei-Lun; Wang, Shiang-Jiu

2014-01-01

367

Cobalt60 and proton radiation effects on large format, 2-D, CCD arrays for an Earth imaging application  

Microsoft Academic Search

Cobalt60 and 10-MeV proton irradiations have been carried out on n-buried channel frame transfer CCDs (charge coupled devices) in order to study changes in charge transfer efficiency (CTE) and dark current for room temperature, 1 ?s\\/pixel, readout conditions. Bias dependence and post-annealing effects were observed for ionization damage. CTE effects are explained in terms of capture and emission from deep

G. R. Hopkinson

1992-01-01

368

Modeling and Measurement of 3D Deformation of Scoliotic Spine Using 2D X-ray Images  

NASA Astrophysics Data System (ADS)

Scoliosis causes deformations such as twisting and lateral bending of the spine. To correct scoliotic deformation, the extents of 3D spinal deformation need to be measured. This paper studies the modeling and measurement of scoliotic spine based on 3D curve model. Through modeling the spine as a 3D Cosserat rod, the 3D structure of a scoliotic spine can be recovered by obtaining the minimum potential energy registration of the rod to the scoliotic spine in the x-ray image. Test results show that it is possible to obtain accurate 3D reconstruction using only the landmarks in a single view, provided that appropriate boundary conditions and elastic properties are included as constraints.

Li, Hao; Leow, Wee Kheng; Huang, Chao-Hui; Howe, Tet Sen

369

Crystal structure and temperature-dependent fluorescent property of a 2D cadmium (II) complex based on 3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid  

NASA Astrophysics Data System (ADS)

A new cadmium (II) organic coordination polymers [Cd(dbtec)0.5(H2O)3]·H2O (1), has been constructed based on 3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid (H4dbtec), and characterized by elemental analysis (EA), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. In 1, ?2-?1:?1 and ?4-?2:?2 dbtec ligands link four hepta-coordinated CdII ions to form a 2D 44 topological layer structure, which is further connected into an interesting 3D network by hydrogen bond and Br⋯O halogen bond. Moreover, the thermal stabilities, solid ultraviolet spectroscopy and temperature-dependent fluorescent properties of 1 were investigated.

Zhang, Liang-Liang; Guo, Yu; Wei, Yan-Hui; Guo, Jie; Wang, Xing-Po; Sun, Dao-Feng

2013-04-01

370

Reconstruction of 3D lung models from 2D planning data sets for Hodgkin's lymphoma patients using combined deformable image registration and navigator channels  

SciTech Connect

Purpose: Late complications (cardiac toxicities, secondary lung, and breast cancer) remain a significant concern in the radiation treatment of Hodgkin's lymphoma (HL). To address this issue, predictive dose-risk models could potentially be used to estimate radiotherapy-related late toxicities. This study investigates the use of deformable image registration (DIR) and navigator channels (NCs) to reconstruct 3D lung models from 2D radiographic planning images, in order to retrospectively calculate the treatment dose exposure to HL patients treated with 2D planning, which are now experiencing late effects. Methods: Three-dimensional planning CT images of 52 current HL patients were acquired. 12 image sets were used to construct a male and a female population lung model. 23 ''Reference'' images were used to generate lung deformation adaptation templates, constructed by deforming the population model into each patient-specific lung geometry using a biomechanical-based DIR algorithm, MORFEUS. 17 ''Test'' patients were used to test the accuracy of the reconstruction technique by adapting existing templates using 2D digitally reconstructed radiographs. The adaptation process included three steps. First, a Reference patient was matched to a Test patient by thorax measurements. Second, four NCs (small regions of interest) were placed on the lung boundary to calculate 1D differences in lung edges. Third, the Reference lung model was adapted to the Test patient's lung using the 1D edge differences. The Reference-adapted Test model was then compared to the 3D lung contours of the actual Test patient by computing their percentage volume overlap (POL) and Dice coefficient. Results: The average percentage overlapping volumes and Dice coefficient expressed as a percentage between the adapted and actual Test models were found to be 89.2{+-}3.9% (Right lung=88.8%; Left lung=89.6%) and 89.3{+-}2.7% (Right=88.5%; Left=90.2%), respectively. Paired T-tests demonstrated that the volumetric reconstruction method made a statistically significant improvement to the population lung model shape (p<0.05). The error in the results were also comparable to the volume overlap difference observed between inhale and exhale lung volumes during free-breathing respiratory motion (POL:p=0.43; Dice:p=0.20), which implies that the accuracies of the reconstruction method are within breathing constraints and would not be the confining factor in estimating normal tissue dose exposure. Conclusions: The result findings show that the DIR-NC technique can achieve a high degree of reconstruction accuracy, and could be useful in approximating 3D dosimetric representations of historical 2D treatment. In turn, this could provide a better understanding of the biophysical relationship between dose-volume exposure and late term radiotherapy effects.

Ng, Angela; Nguyen, Thao-Nguyen; Moseley, Joanne L.; Hodgson, David C.; Sharpe, Michael B.; Brock, Kristy K. [Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9, Canada and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada)

2010-03-15

371

2D numerical modelling of the gas temperature in a high-temperature high-power strontium atom laser excited by nanosecond pulsed longitudinal discharge in a He-SrBr2 mixture  

NASA Astrophysics Data System (ADS)

Assuming axial symmetry and a uniform power input, a 2D model (r, z) is developed numerically for determination of the gas temperature in the case of a nanosecond pulsed longitudinal discharge in He-SrBr2 formed in a newly-designed large-volume high-temperature discharge tube with additional incompact ZrO2 insulation in the discharge-free zone, in order to find the optimal thermal mode for achievement of maximal output laser parameters. The model determines the gas temperature of a nanosecond pulsed longitudinal discharge in helium with small additives of strontium and bromine.

Chernogorova, T. P.; Temelkov, K. A.; Koleva, N. K.; Vuchkov, N. K.

2014-05-01

372

Near-infrared (NIR) imaging analysis of polylactic acid (PLA) nanocomposite by multiple-perturbation two-dimensional (2D) correlation spectroscopy  

NASA Astrophysics Data System (ADS)

Multiple-perturbation two-dimensional (2D) correlation spectroscopy was applied to sets of near-infrared (NIR) imaging data of polylactic acid (PLA) nanocomposite samples undergoing UV degradation. Incorporation of clay nanoparticles substantially lowers the surface free energy barrier for the nucleation of PLA and eventually increases the frequency of the spontaneous nucleation of PLA crystals. Thus, when exposed to external stimuli such as UV light, PLA nanocomposite may show different structure alternation depending on the clay dispersion. Multiple-perturbation 2D correlation analysis of the PLA nanocomposite samples revealed different spatial variation between crystalline and amorphous structure of PLA, and the phenomenon especially becomes acute in the region where the clay particles are coagulated. The incorporation of the clay leads to the cleavage-induced crystallization of PLA when the sample is subjected to the UV light. The additional development of the ordered crystalline structure then works favorably to restrict the initial degradation of the polymer, providing the delay in the weight loss of the PLA.

Shinzawa, Hideyuki; Murakami, Takurou N.; Nishida, Masakazu; Kanematsu, Wataru; Noda, Isao

2014-07-01

373

Intrinsic Signal Amplification in the Application of 2D SENSE Parallel Imaging to 3D Contrast-Enhanced Elliptical Centric MRA and MRV  

PubMed Central

The relative signal-to-noise ratio (SNR) provided by 2D sensitivity encoding (SENSE) when applied to 3D contrast-enhanced MR angiography (CE-MRA) is studied. If an elliptical centric phase-encoding order is used to map the waning magnetization of the contrast bolus to k-space, the application of SENSE will reduce the degree of k-space signal modulation, providing a signal amplification A over corresponding nonaccelerated acquisitions. This offsets the SNR loss in R-accelerated SENSE due to R and the geometry (g) factor. The theoretical bound on A is R and is reduced from this depending on the properties of the bolus profile and the duration over which it is imaged. In this work a signal amplification of 1.14–1.23 times that of nonvascular background tissue is demonstrated in a study of 20 volunteers using R = 4 2D SENSE whole-brain MR venography (MRV). The effects of a nonuniform g-factor and inhomogeneity of background tissue are accounted for. The observed amplification compares favorably with the value of 1.31 predicted numerically from a measured bolus curve.

Riederer, Stephen J.; Hu, Houchun Harry; Kruger, David G.; Haider, Clifton R.; Campeau, Norbert G.; Huston, John

2012-01-01

374

The 2009-11 SAHKE Experiment: 2D velocity imaging across the interseismically locked southern Hikurangi margin, Wellington, New Zealand  

NASA Astrophysics Data System (ADS)

The passive and controlled source Seismic Array HiKurangi Experiment (SAHKE) project is designed to investigate the structure of the forearc and the physical parameters controlling locking at the Australian-Pacific subduction plate boundary beneath the southern North Island. SAHKE seismic data were acquired between November 2009 and April 2010 and again in May 2011, encompassing the full extent of the locked portion of the plate interface beneath Wellington along a central transect. 400 km of marine multichannel seismic data were acquired on two SAHKE profiles across the convergent margin and recorded by 38 IRIS/PASSCAL short period sensors along the main onshore-offshore transect. The onshore component of the survey comprised 12 in-line borehole explosive sources (500 kg) distributed approximately 8 km apart along the central transect. The energy was recorded on 835 seismic stations (277 3-component and 558 vertical sensors) deployed at 100 m spacing, except for a denser section of 50 m spacing in the centre of the spread. The 3C stations were spaced at 300 m spacing. We used a tomographic inversion of 18000 first arrivals, from the combined onshore-offshore and onshore components, to construct a Vp image of the crust that is well resolved to 20-25 km depth. The resulting velocity models shows top of Pacific plate subducting as a strong velocity gradient offshore to the east but this gradient decreases beneath the land and also coincides with a low velocity lower crust. A stacked section of the land shots also reveals the low velocity zone to be highly imbricated and consistent with subducted sedimentary channel material being underplated in the region of strongest geodetically determined plate coupling. The Wairarapa fault, a prominent upper crustal splay fault, appears to dip westward and merge with the underplated reflectivity beneath the Tararua Ranges.

Henrys, S. A.; Wech, A.; Sato, H.; Okaya, D. A.; Iwasaki, T.; Stern, T. A.; Savage, M. K.; Mochizuki, K.; Kurashimo, E.; Sutherland, R.

2012-12-01

375

First Ion Temperature Images from TWINS Data  

NASA Astrophysics Data System (ADS)

Ion heating has been correlated with several magnetospheric phenomena, including magnetic reconnection, instabilities, and convection of plasma through different regions of the magnetosphere. Thus, it is important to be able to measure ion temperatures throughout the magnetosphere to better understand the physics of these phenomena. Effective ion temperatures based on the charge-exchange cross section-corrected energetic neutral atom (ENA) flux versus energy spectrum can be calculated from TWINS data. Effective ion temperatures calculated from the Medium Energy Neutral Atom (MENA) imager on the IMAGE spacecraft using this technique were shown to have excellent (within ˜30%) agreement with in-situ measurements from MPA instruments on LANL geosynchronous spacecraft and GEOTAIL. In order to achieve adequate statistics for reliable ion temperature calculations, we can use either data with significant ENA flux rates, such as during geomagnetic storms, or superpositions of multiple data sets. We present ion temperature images from the few small storms that have occurred so far in the TWINS mission as well as preliminary results of a superposition study of the quiet-time magnetosphere.

Keesee, Amy; Scime, Earl

2009-11-01

376

(2D)2PCA+(2D)2LDA: a new feature extraction for face recognition  

NASA Astrophysics Data System (ADS)

In this paper, we combine the advantages of (2D)2PCA and (2D)2LDA, and propose a two-stage framework: "(2D)2PCA+(2D)2LDA". In the first stage, a two-directional 2D feature extraction technique, (2D)2PCA, is employed to condense the dimension of image matrix; in the second stage, the two-directional 2D linear discriminant analysis (2D)2LDA is performed in the (2D)2PCA subspace to find the optimal discriminant feature vectors. In addition, the proposed method can take full advantage of the descriptive information and discriminant information of the image. Experiments conducted on ORL and Yale face databases demonstrate the effectiveness and robustness of the proposed method.

Huang, Guohong

2011-04-01

377

Imaging the Ferron Member of the Mancos Shale formation using reprocessed high-resolution 2-D seismic reflection data: Emery County, Utah  

USGS Publications Warehouse

Late in 1982 and early in 1983, Arco Exploration contracted with Rocky Mountain Geophysical to acquired four high-resolution 2-D multichannel seismic reflection lines in Emery County, Utah. The primary goal in acquiring this data was an attempt to image the Ferron Member of the Upper Cretaceous Mancos Shale. Design of the high-resolution 2-D seismic reflection data acquisition used both a short geophone group interval and a short sample interval. An explosive energy source was used which provided an input pulse with broad frequency content and higher frequencies than typical non-explosive Vibroseis?? sources. Reflections produced by using this high-frequency energy source when sampled at a short interval are usually able to resolve shallow horizons that are relatively thin compared to those that can be resolved using more typical oil and gas exploration seismic reflection methods.The U.S. Geological Survey-Energy Resources Program, Geophysical Processing Group used the processing sequence originally applied by Arco in 1984 as a guide and experimented with processing steps applied in a different order using slightly different parameters in an effort to improve imaging the Ferron Member horizon. As with the Arco processed data there are sections along all four seismic lines where the data quality cannot be improved upon, and in fact the data quality is so poor that the Ferron horizon cannot be imaged at all.Interpretation of the seismic and core hole data indicates that the Ferron Member in the study area represent a deltaic sequence including delta front, lower delta plain, and upper delta plain environments. Correlating the depositional environments for the Ferron Member as indicated in the core holes with the thickness of Ferron Member suggests the presence of a delta lobe running from the northwest to the southeast through the study area. The presence of a deltaic channel system within the delta lobe complex might prove to be an interesting conventional exploration target along with the coal-bed methane production already proven in the area. ?? 2003 Elsevier B.V. All rights reserved.

Taylor, D. J.

2003-01-01

378

HIGH TIME-RESOLVED, 2-D IMAGING OF TYPE-1 ELMs IN DIII-D USING A IMAGE-INTENSIFIED CID CAMERA  

SciTech Connect

The evolution of 2-D emission profiles of D{sub {alpha}} and C III during type-I ELMs has been investigated in DIII-D using a tangentially viewing gated, intensified charge-injected device (CID) camera. The measured CIII emission profiles indicate transient inner leg attachment with the arrival of the ELM heat pulse. The measured D{sub {alpha}} emission profiles during an ELM cycle show enhanced deuterium recycling during the deposition of the ELM particle pulse at the target, which suggests the detachment of the divertor plasma from the target plates. Measurements taken in ELMy H-mode discharges at densities of 50% and 90% of the Greenwald density limit are compared utilizing the CID camera system and a comprehensive set of other divertor diagnostics. An ELM model based on fluid and PIC simulations is used to discuss the observation on the response of the divertor plasma to the ELM heat and particle pulse.

GROTH, M.; FENSTERMACHER, M.E.; BOEDO, J.A.; BROOKS,N.H.; GRAY, D.S.; LASNIER, C.J.; LEONARD, A.W.; PORTER, G.D.; WATKINS, J.G.

2002-06-01

379

Development of a soft-X ray detector for energy resolved 2D imaging by means of a Gas Pixel Detector with highly integrated microelectronics  

SciTech Connect

Soft-X ray 2-D imaging on ITER is not considered yet. We propose a new approach, based on a gas detector with a gas electron multiplier (GEM) as amplifying structure and with a two-dimensional readout fully integrated with the front end electronics, through an ASIC developed on purpose. The concept has been already tested by means of a prototype, with 128 pixels, carried out in Frascati in collaboration with INFN-Pisa and tested on FTU in 2001 and NSTX in 2002-2004. Thanks to the photon counting mode, it provides 2-D imaging with high time resolution (sub millisecond), high sensitivity and signal to noise ratio. Its capability of energy discrimination allows the acquisition of pictures in X-ray energy bands or to perform a spectral scan in the full energy interval. We propose the realisation of such kind a detector with a readout microchip (ASIC) equipped with 105600 hexagonal pixels arranged at 70 {mu}m pitch in a 300x352 honeycomb matrix, corresponding to an active area of 2.1x2.1 cm{sup 2}, with a pixel density of 240 pixels/ mm{sup 2}. Each pixel is connected to a charge sensitive amplifier followed by a discriminator of pulse amplitude and counter. The chip integrates more than 16.5 million transistors and it is subdivided in 64 identical clusters, to be read independently each other. An important part of the work will be also the design of the whole detector to fulfil all the constraints and requirements as plasma diagnostic in a tokamak machine. Since the detector has high and controllable intrinsic gain, it works well even at very low photon energy, ranging from 0.2 keV to 10 keV (X-VUV region). This range appears therefore particularly suitable for ITER to monitor the outer part of the plasma. In particular pedestal physics, edge modes, localization and effects of additional heating, boundary plasma control etc. The capability of this proposed detector to work in this energy range is further valuable because solid state detectors are not favorite at low energy because of the lack of intrinsic gain.

Pacella, D.; Pizzicaroli, G. [Associazione Euratom-ENEA sulla Fusione, Frascati (Italy); Romano, A.; Gabellieri, L.; Bellazzini, R.; Brez, A. [Istituto Nazionale Fisica Nucleare, Pisa (Italy)

2008-03-12

380

A novel material detection algorithm based on 2D GMM-based power density function and image detail addition scheme in dual energy X-ray images.  

PubMed

Material detection is a vital need in dual energy X-ray luggage inspection systems at security of airport and strategic places. In this paper, a novel material detection algorithm based on statistical trainable models using 2-Dimensional power density function (PDF) of three material categories in dual energy X-ray images is proposed. In this algorithm, the PDF of each material category as a statistical model is estimated from transmission measurement values of low and high energy X-ray images by Gaussian Mixture Models (GMM). Material label of each pixel of object is determined based on dependency probability of its transmission measurement values in the low and high energy to PDF of three material categories (metallic, organic and mixed materials). The performance of material detection algorithm is improved by a maximum voting scheme in a neighborhood of image as a post-processing stage. Using two background removing and denoising stages, high and low energy X-ray images are enhanced as a pre-processing procedure. For improving the discrimination capability of the proposed material detection algorithm, the details of the low and high energy X-ray images are added to constructed color image which includes three colors (orange, blue and green) for representing the organic, metallic and mixed materials. The proposed algorithm is evaluated on real images that had been captured from a commercial dual energy X-ray luggage inspection system. The obtained results show that the proposed algorithm is effective and operative in detection of the metallic, organic and mixed materials with acceptable accuracy. PMID:22635176

Pourghassem, Hossein

2012-01-01

381

2D-Ising Model  

NSDL National Science Digital Library

The EJS 2D Ising model displays a lattice of spins. You can change the lattice size, temperature, and external magnetic field. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The 2D-Ising model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_Ising2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-02-20

382

Preliminary evidence for white matter metabolite differences in marijuana dependent young men using 2D J-resolved magnetic resonance spectroscopic imaging at 4 Tesla  

PubMed Central

Chronic marijuana (MRJ) use is associated with altered cognition and mood state, altered brain metabolites, functional and structural brain changes. The objective of this study was to apply proton magnetic resonance spectroscopic imaging (MRSI) to compare proton metabolite levels in 15 young men with MRJ-dependence and 11 healthy non-using (NU) young men. Spectra were acquired at 4.0 Tesla using 2D J-resolved MRSI to resolve coupled resonances in J-space and to quantify the entire J-coupled spectral surface of metabolites from voxels containing basal ganglia and thalamus, temporal and parietal lobe, and occipital white and gray matter. This method permitted investigation of high-quality spectra for regression analyses to examine metabolites relative to tissue type. Distribution of myo-inositol (mI)/creatine (Cr) was altered in the MRJ group whereas the NU group exhibited higher mI/Cr in WM than GM, this pattern was not observed in MRJ subjects. Significant relationships observed between global mI/Cr and distribution in WM, and self-reported impulsivity and mood symptoms were also unique between MRJ and NU groups. These preliminary findings suggest that mI, and distribution of this glial metabolite in WM, is altered by MRJ use and is associated with behavioral and affective features reported by young MRJ-dependent men.

Silveri, Marisa M.; Jensen, J. Eric; Rosso, Isabelle M.; Sneider, Jennifer T.; Yurgelun-Todd, Deborah A.

2010-01-01