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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

Infrared imaging of 2-D temperature distribution during cryogen spray cooling.  

PubMed

Cryogen spray cooling (CSC) is used in conjunction with pulsed laser irradiation for treatment of dermatologic indications. The main goal of this study was to determine the radial temperature distribution created by CSC and evaluate the importance of radial temperature gradients upon the subsequent analysis of tissue cooling throughout the skin. Since direct measurement of surface temperatures during CSC are hindered by the formation of a liquid cryogen layer, temperature distributions were estimated using a thin, black aluminum sheet. An infrared focal plane array camera was used to determine the 2-D backside temperature distribution during a cryogen spurt, which preliminary measurements have shown is a good indicator of the front-side temperature distribution. The measured temperature distribution was approximately gaussian in shape. Next, the transient temperature distributions in skin were calculated for two cases: 1) the standard 1-D solution which assumes a uniform cooling temperature distribution, and 2) a 2-D solution using a nonuniform surface cooling temperature distribution based upon the back-side infrared temperature measurements. At the end of a 100-ms cryogen spurt, calculations showed that, for the two cases, large discrepancies in temperatures at the surface and at a 60-micron depth were found at radii greater than 2.5 mm. These results suggest that it is necessary to consider radial temperature gradients during cryogen spray cooling of tissue. PMID:12596634

Choi, Bernard; Welch, Ashley J

2002-12-01

3

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

4

2D microwave imaging reflectometer electronicsa)  

NASA Astrophysics Data System (ADS)

A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.

Spear, A. G.; Domier, C. W.; Hu, X.; Muscatello, C. M.; Ren, X.; Tobias, B. J.; Luhmann, N. C.

2014-11-01

5

An improved colorimetric method for visualization of 2-D, inhomogeneous temperature distribution in a gas fired industrial furnace by radiation image processing  

Microsoft Academic Search

The reconstruction of multi-dimensional, inhomogeneous combustion temperature distribution inside industrial furnaces through flame radiation images is very difficult. This is because the radiation contributed to the radiation images from the high temperature furnace wall surfaces is higher than that from water-cooled tubes in utility boilers. Based on the monochromatic intensity distributions reconstructed from the monochromatic intensity images transferred from color

Xiangyu Zhang; Qiang Cheng; Chun Lou; Huaichun Zhou

2011-01-01

6

3D Modeling From 2D Images  

Microsoft Academic Search

This article will give an overview of the methods of transition from the set of images into 3D model. Direct method of creating 3D model using 3D software will be described. Creating photorealistic 3D models from a set of photographs is challenging problem in computer vision because the technology is still in its development stage while the demands for 3D

Lana Madracevic; Stjepan Sogoric

2010-01-01

7

Hidden Line Removal for 2D Cartoon Images  

Microsoft Academic Search

In this paper, we describe a hidden line removal scheme for 2D cartoon images. The depths are introduced to the polylines of the image. The surfaces of the image are classified and their depths updated according to the depths of polylines forming the surfaces. The hidden lines are identified b y comparing the depths of the polylines with the depths

Zhanggui Zeng; Hong Yan

2001-01-01

8

Photorealistic image synthesis and camera validation from 2D images  

NASA Astrophysics Data System (ADS)

This paper presents a new 3D scene reconstruction technique using the Unity 3D game engine. The method presented here allow us to reconstruct the shape of simple objects and more complex ones from multiple 2D images, including infrared and digital images from indoor scenes and only digital images from outdoor scenes and then add the reconstructed object to the simulated scene created in Unity 3D, these scenes are then validated with real world scenes. The method used different cameras settings and explores different properties in the reconstructions of the scenes including light, color, texture, shapes and different views. To achieve the highest possible resolution, it was necessary the extraction of partial textures from visible surfaces. To recover the 3D shapes and the depth of simple objects that can be represented by the geometric bodies, there geometric characteristics were used. To estimate the depth of more complex objects the triangulation method was used, for this the intrinsic and extrinsic parameters were calculated using geometric camera calibration. To implement the methods mentioned above the Matlab tool was used. The technique presented here also let's us to simulate small simple videos, by reconstructing a sequence of multiple scenes of the video separated by small margins of time. To measure the quality of the reconstructed images and video scenes the Fast Low Band Model (FLBM) metric from the Video Quality Measurement (VQM) software was used. Low bandwidth perception based features include edges and motion.

Santos Ferrer, Juan C.; González Chévere, David; Manian, Vidya

2014-06-01

9

2D/3D Image Registration using Regression Learning  

PubMed Central

In computer vision and image analysis, image registration between 2D projections and a 3D image that achieves high accuracy and near real-time computation is challenging. In this paper, we propose a novel method that can rapidly detect an object’s 3D rigid motion or deformation from a 2D projection image or a small set thereof. The method is called CLARET (Correction via Limited-Angle Residues in External Beam Therapy) and consists of two stages: registration preceded by shape space and regression learning. In the registration stage, linear operators are used to iteratively estimate the motion/deformation parameters based on the current intensity residue between the target projec-tion(s) and the digitally reconstructed radiograph(s) (DRRs) of the estimated 3D image. The method determines the linear operators via a two-step learning process. First, it builds a low-order parametric model of the image region’s motion/deformation shape space from its prior 3D images. Second, using learning-time samples produced from the 3D images, it formulates the relationships between the model parameters and the co-varying 2D projection intensity residues by multi-scale linear regressions. The calculated multi-scale regression matrices yield the coarse-to-fine linear operators used in estimating the model parameters from the 2D projection intensity residues in the registration. The method’s application to Image-guided Radiation Therapy (IGRT) requires only a few seconds and yields good results in localizing a tumor under rigid motion in the head and neck and under respiratory deformation in the lung, using one treatment-time imaging 2D projection or a small set thereof. PMID:24058278

Chou, Chen-Rui; Frederick, Brandon; Mageras, Gig; Chang, Sha; Pizer, Stephen

2013-01-01

10

2D ocean surface SAR images simulation: a statistical approach  

Microsoft Academic Search

This paper outlines a method for simulating the ocean surface as seen by a space borne synthetic aperture radar (SAR). A statistical approach was chosen in order to integrate the different mechanisms responsible for the imaging of the surface waves. A 2D sea-state surface was simulated, then divided in facets (of approximately the size of a resolution cell) and each

R. Garello; S. Proust; B. Chapron

1993-01-01

11

Image processing of 2D resistivity data for imaging faults  

NASA Astrophysics Data System (ADS)

A methodology to locate automatically limits or boundaries between different geological bodies in 2D electrical tomography is proposed, using a crest line extraction process in gradient images. This method is applied on several synthetic models and on field data set acquired on three experimental sites during the European project PALEOSIS where trenches were dug. The results presented in this work are valid for electrical tomographies data collected with a Wenner-alpha array and computed with an l 1 norm (blocky inversion) as optimization method. For the synthetic cases, three geometric contexts are modelled: a vertical and a dipping fault juxtaposing two different geological formations and a step-like structure. A superficial layer can cover each geological structure. In these three situations, the method locates the synthetic faults and layer boundaries, and determines fault displacement but with several limitations. The estimated fault positions correlate exactly with the synthetic ones if a conductive (or no superficial) layer overlies the studied structure. When a resistive layer with a thickness of 6 m covers the model, faults are positioned with a maximum error of 1 m. Moreover, when a resistive and/or a thick top layer is present, the resolution significantly decreases for the fault displacement estimation (error up to 150%). The tests with the synthetic models for surveys using the Wenner-alpha array indicate that the proposed methodology is best suited to vertical and horizontal contacts. Application of the methodology to real data sets shows that a lateral resistivity contrast of 1:5-1:10 leads to exact faults location. A fault contact with a resistivity contrast of 1:0.75 and overlaid by a resistive layer with a thickness of 1 m gives an error location ranging from 1 to 3 m. Moreover, no result is obtained for a contact with very low contrasts (˜1:0.85) overlaid by a resistive soil. The method shows poor results when vertical gradients are greater than horizontal ones. This kind of image processing technique should be systematically used for improving the objectiveness of tomography interpretation when looking for limits between geological objects.

Nguyen, F.; Garambois, S.; Jongmans, D.; Pirard, E.; Loke, M. H.

2005-07-01

12

Imaging and diffraction characterisation of 2D inorganic nanostructures  

NASA Astrophysics Data System (ADS)

2D nanomaterials are a novel class of materials, noted for their potential in a range of high impact applications, such as sensing catalysis, and composite reinforcement. However, their structural features have not yet been fully characterised. In this work we have shown that 2D nanostructures of hBN, MoS2, and WS2, prepared by liquid exfoliation, can stack in sequences different from the bulk stacking. In 2D hBN non-sequential stacking was observed. 2D MoS2 and WS2 appear to have stacking where Mo/W atoms are located on the top of each other which differs from naturally occurring 2H and 3R polytypes. The majority of the hBN and MoS2 2D nanostructures retain the stacking of their bulk counterparts, while in 2D WS2 non-bulk stacking dominates. The conclusions are based primarily on the atomically resolved ADF STEM images with supporting evidence from electron diffraction.

Shmeliov, A.; Shannon, M.; Wang, P.; E, H.; Nellist, P. D.; Nicolosi, V.

2012-07-01

13

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. PMID:21262842

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

2011-01-01

14

Volumetric elasticity imaging with a 2-D CMUT array.  

PubMed

This article reports the use of a two-dimensional (2-D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio-frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare three-dimensional (3-D) elasticity imaging methods. Typical 2-D motion tracking for elasticity image formation was compared with three different methods of 3-D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2-D search), planar search, combination of multiple planes and plane independent guided search. The cross-correlation between the predeformation and motion-compensated postdeformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3-D modulus reconstruction, high quality 3-D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188

Fisher, Ted G; Hall, Timothy J; Panda, Satchi; Richards, Michael S; Barbone, Paul E; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve

2010-06-01

15

Volumetric Elasticity Imaging with a 2D CMUT Array  

PubMed Central

This paper reports the use of a two-dimensional (2D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare 3D elasticity imaging methods. Typical 2D motion tracking for elasticity image formation was compared to three different methods of 3D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2D search), planar search, combination of multiple planes, and plane independent guided search. The cross correlation between the pre-deformation and motion-compensated post-deformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3D modulus reconstruction, high quality 3D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188

Fisher, Ted G.; Hall, Timothy J.; Panda, Satchi; Richards, Michael S.; Barbone, Paul E.; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve

2010-01-01

16

Automatic segmentation of scaling in 2-D psoriasis skin images.  

PubMed

Psoriasis is a chronic inflammatory skin disease that affects over 3% of the population. Various methods are currently used to evaluate psoriasis severity and to monitor therapeutic response. The PASI system of scoring is widely used for evaluating psoriasis severity. It employs a visual analogue scale to score the thickness, redness (erythema), and scaling of psoriasis lesions. However, PASI scores are subjective and suffer from poor inter- and intra-observer concordance. As an integral part of developing a reliable evaluation method for psoriasis, an algorithm is presented for segmenting scaling in 2-D digital images. The algorithm is believed to be the first to localize scaling directly in 2-D digital images. The scaling segmentation problem is treated as a classification and parameter estimation problem. A Markov random field (MRF) is used to smooth a pixel-wise classification from a support vector machine (SVM) that utilizes a feature space derived from image color and scaling texture. The training sets for the SVM are collected directly from the image being analyzed giving the algorithm more resilience to variations in lighting and skin type. The algorithm is shown to give reliable segmentation results when evaluated with images with different lighting conditions, skin types, and psoriasis types. PMID:23288330

Lu, Juan; Kazmierczak, Ed; Manton, Jonathan H; Sinclair, Rodney

2013-04-01

17

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

18

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

19

Non-rigid 2D-3D Medical Image Registration using Markov Random Fields  

E-print Network

Non-rigid 2D-3D Medical Image Registration using Markov Random Fields Enzo Ferrante and Nikos of this approach. Keywords: 2D-3D registration, medical imaging, markov random fields, dis- crete optimization. 1 Introduction 2D-3D image registration is an important problem in medical imaging and it can be applied

20

Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan  

E-print Network

Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan Yoav out analytical characterizations on chemical and biochemical samples [2,3] 2D NMR probably finds its resonance imaging (MRI). In spite of the dissimilar information being sought in 2D NMR and 2D MRI

Frydman, Lucio

21

2D luminescence imaging of physiological wound oxygenation.  

PubMed

In cutaneous wound healing, the role of oxygen in vivo is poorly understood. We studied wound surface pO(2) during physiological wound healing in humans. Split-thickness skin graft donor sites (n=12) served as standardized wound models. Wound surface pO(2) was measured at 1, 6 and 14days after split-skin harvesting using two-dimensional luminescence lifetime imaging (2D-LLI) of palladium(II)-meso-tetraphenyl-tetrabenzoporphyrin (Pd-TPTBP) in polystyrene-co-acrylonitrile (PSAN) particles on transparent foils. In another experiment, we removed the stratum corneum (SC) on the volar forearm (n=10) by tape strippings to study the impact of the SC on the epidermal oxygen barrier. Split-skin donor site pO(2) significantly decreased during the time course of physiological healing. Regional differences in pO(2) within donor site wounds were visualized for the first time in literature. No difference was found in pO(2) before and after SC removal, showing that the SC is not a major constituent of the epidermal oxygen barrier. PMID:21443617

Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Maisch, Tim; Szeimies, Rolf-Markus; Landthaler, Michael; Regensburger, Johannes; Santarelli, Francesco; Klimant, Ingo; Babilas, Philipp

2011-07-01

22

LOW BIT-RATE IMAGE CODING USING 2-D LINEAR PRRDICTION AND 2-D STOCHASTIC EXCITATION  

E-print Network

of this coding method for image coding and study its different parameters.Weshowthatitisnot necessary to transmit to represent the prediction residual signal. In order to get good performance from this coder, it is necessary) coder 151 and the regular pulse excited (RPE) coder 161. Tn the speech coding area, the linear

23

Non-rigid 2D-3D Medical Image Registration using Markov Random Fields  

E-print Network

guided surgeries, as laparoscopic or endoscopic [1], and brain surgeries [2] use such images. In those)) and intra-operative 2D images are used to guide surgeons during the procedure. 2D-3D registration plays nonrigid registration algorithms used to register histological section images to human brain MRI. A feature

Paris-Sud XI, Université de

24

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

25

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

26

Oscillating adiabatic temperature change of 2D diamagnetic materials  

NASA Astrophysics Data System (ADS)

Studies on magnetocaloric effect generally concern ferromagnetic materials, due to their high magnetocaloric potential near phase transitions. Recently, this effect on diamagnetic materials was explored and oscillations on the entropy change observed as a consequence of the crossing of the Landau levels through the Fermi energy. The present paper explores the adiabatic temperature change in graphenes and thin films of non-relativistic diamagnetic materials and then compares the results with those from 3D diamagnets. Applying 10 T of magnetic field, the temperature change of a gold thin film reaches 1 K, while for bulk gold the temperature change is smaller than 6 mK. For graphenes, the temperature change reaches 4 K with a field of ~1 T.

Paixão, L. S.; Alisultanov, Z. Z.; Reis, M. S.

2014-11-01

27

IMAGE RESTORATION IN 2-D STRUCTURED ILLUMINATION MICROSCOPY  

Microsoft Academic Search

Structured illumination has been used to extend the resolution of wide field fluorescence microscopy, doubling the resolution of the wide field microscopy (1). In that approach, multiple images are acquired for a number of phases and orientations of the illumination pattern. These images were combined in (1) to form the higher resolution image by a linear algorithm that places each

Walter A. Carrington

28

Probabilistic human pose recovery from 2D images  

Microsoft Academic Search

Image based human pose recovery has many applications in different industries such as games, entertainment, physiological rehabilitation and biometrics. This paper presents a new pose estimation algorithm from monocular images based on a nonlinear mapping of human silhouettes, coded using a collection of local image moments, to the pose space using a mixture of Neural Networks (NN) regressors. All parameters

Farid Flitti; Mohammed Bennamoun; Du Q. Huynh; Robyn A. Owens

2010-01-01

29

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

30

Finite-temperature three-point function in 2D CFT  

NASA Astrophysics Data System (ADS)

We calculate the finite temperature three-point correlation function for primary fields in a 2D conformal field theory in momentum space. This result has applications to any strongly coupled field theory with a 2D CFT dual, as well as to Kerr/CFT.

Becker, Melanie; Cabrera, Yaniel; Su, Ning

2014-09-01

31

2D\\/3D Mixed Service in T-DMB System Using Depth Image Based Rendering  

Microsoft Academic Search

In this paper, we introduce a 2D\\/3D mixed service in terrestrial digital multimedia broadcasting (T-DMB) system using depth-image-based rendering (DIBR). The 2D\\/3D mixed service is the 3D service type that 3D contents are shown partially while a 2D video sequence is displayed in the entire screen, or vice versa. This service is very attractive because partial display of 3D contents

KwangHee Jung; Young Kyung Park; Joong Kyu Kim; Hyun Lee; KugJin Yun; NamHo Hur; JinWoong Kim

2008-01-01

32

Connectivity-preserving parallel operators in 2D and 3D images  

Microsoft Academic Search

Connectivity preservation is a concern in the design of parallel reduction processes for 2D and 3D image processing algorithms. Algorithm designers need efficient and available connectivity preservation tasks to prove algorithm correctness. Although efficient 2D tests are known, efficient 3D tests still need to be developed. We review earlier results for 2D connectivity preservation tests and demonstrate several 'design spaces'

Richard W. Hall

1993-01-01

33

3D/2D convertible projection-type integral imaging using concave half mirror array.  

PubMed

We propose a new method for implementing 3D/2D convertible feature in the projection-type integral imaging by using concave half mirror array. The concave half mirror array has the partially reflective characteristic to the incident light. And the reflected term is modulated by the concave mirror array structure, while the transmitted term is unaffected. With such unique characteristic, 3D/2D conversion or even the simultaneous display of 3D and 2D images is also possible. The prototype was fabricated by the aluminum coating and the polydimethylsiloxane molding process. We could experimentally verify the 3D/2D conversion and the display of 3D image on 2D background with the fabricated prototype. PMID:20940957

Hong, Jisoo; Kim, Youngmin; Park, Soon-gi; Hong, Jong-Ho; Min, Sung-Wook; Lee, Sin-Doo; Lee, Byoungho

2010-09-27

34

Temperature-jump 2D IR spectroscopy to study protein conformational dynamics  

E-print Network

Temperature-jump (T-jump) two-dimensional infrared spectroscopy (2D IR) is developed, characterized, and applied to the study of protein folding and association. In solution, protein conformational changes span a wide range ...

Jones, Kevin C. (Kevin Chapman)

2012-01-01

35

Hydrogen Bond Rearrangements in Water Probed with Temperature-Dependent 2D IR  

E-print Network

We use temperature-dependent two-dimensional infrared spectroscopy (2D IR) of dilute HOD in H2O to investigate hydrogen bond rearrangements in water. The OD stretching frequency is sensitive to its environment, and loss ...

Nicodemus, Rebecca A.

36

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

37

Constrained Reconstruction Applied to 2-D Chemical Shift Imaging  

Microsoft Academic Search

The method of constrained reconstruction, previously applied to magnetic resonance imaging (MRI), is extended to magnetic resonance spectroscopy. This method assumes a model for the MR signal. The model parameters are estimated directly from the phase encoded data. This process obviates the need for the fast Fourier transform (FFT) (which often exhibits limited resolution and ringing artifact). The technique is

Keith A. Wear; Kyle J. Myers; Sunder S. Rajan; Laurence W. Grossman

1997-01-01

38

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

39

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

40

2D Feature Recognition And 3d Reconstruction In Solar Euv Images  

NASA Astrophysics Data System (ADS)

EUV images show the solar corona in a typical temperature range of T >rsim 1 MK, which encompasses the most common coronal structures: loops, filaments, and other magnetic structures in active regions, the quiet Sun, and coronal holes. Quantitative analysis increasingly demands automated 2D feature recognition and 3D reconstruction, in order to localize, track, and monitor the evolution of such coronal structures. We discuss numerical tools that “fingerprint” curvi-linear 1D features (e.g., loops and filaments). We discuss existing finger-printing algorithms, such as the brightness-gradient method, the oriented-connectivity method, stereoscopic methods, time-differencing, and space time feature recognition. We discuss improved 2D feature recognition and 3D reconstruction techniques that make use of additional a priori constraints, using guidance from magnetic field extrapolations, curvature radii constraints, and acceleration and velocity constraints in time-dependent image sequences. Applications of these algorithms aid the analysis of SOHO/EIT, TRACE, and STEREO/SECCHI data, such as disentangling, 3D reconstruction, and hydrodynamic modeling of coronal loops, postflare loops, filaments, prominences, and 3D reconstruction of the coronal magnetic field in general.

Aschwanden, Markus J.

2005-05-01

41

A Comparison of Simularity Measures for use in 2D-3D Medical Image Registration  

Microsoft Academic Search

A comparison of six similarity measures for use in intensity-based two-dimensional-three-dimensional (2-D-3-D) image registration is presented. The accuracy of the similarity measures are compared to a \\

Graeme P. Penney; Jürgen Weese; John A. Little; Paul Desmedt; Derek L. G. Hill; David J. Hawkes

1998-01-01

42

2-D image segmentation using minimum spanning trees  

SciTech Connect

This paper presents a new algorithm for partitioning a gray-level image into connected homogeneous regions. The novelty of this algorithm lies in the fact that by constructing a minimum spanning tree representation of a gray-level image, it reduces a region partitioning problem to a minimum spanning tree partitioning problem, and hence reduces the computational complexity of the region partitioning problem. The tree-partitioning algorithm, in essence, partitions a minimum spanning tree into subtrees, representing different homogeneous regions, by minimizing the sum of variations of gray levels over all subtrees under the constraints that each subtree should have at least a specified number of nodes, and two adjacent subtrees should have significantly different average gray-levels. Two (faster) heuristic implementations are also given for large-scale region partitioning problems. Test results have shown that the segmentation results are satisfactory and insensitive to noise.

Xu, Y.; Uberbacher, E.C.

1995-09-01

43

Detection of sinkholes using 2D electrical resistivity imaging  

NASA Astrophysics Data System (ADS)

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 areas are located in the dolomites of the Lyttelton Formation, which forms part of the Malamani Subgroup and Chuniespoort Group of the Transvaal Supergroup. The survey results suggest that RESTOM is an ideal geophysical tool to aid in the detection and monitoring of sinkholes and other subsurface cavities.

van Schoor, Michael

2002-07-01

44

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

PubMed

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. PMID:21330971

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

2011-01-01

45

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

46

Correlation-autofocusing-spectral 2-D ISAR image reconstruction from linear frequency modulated signals  

Microsoft Academic Search

In this paper, by applying an analytic geometric approach, a model of an ISAR (inverse synthetic aperture radar) signal with linear frequency modulation is developed. An ISAR scenario of the rectilinear movement of a 2D target in the 3D coordinate system is described. An image reconstruction procedure, independent of the trajectory parameters of the target is suggested. The image processing

A. D. Lazarov; C. N. Minchev

2002-01-01

47

2D temperature field measurement in a direct-injection engine using LIF technology  

NASA Astrophysics Data System (ADS)

A new multi-spectral detection strategy for temperature laser- induced- fluorescence (LIF) 2-D imaging measurements is reported for high pressure flames in high-speed diesel engine. Schematic of the experimental set-up is outlined and the experimental data on the diesel engine is summarized. Experiment injection system is a third generation Bosch high-pressure common rail featuring a maximum pressure of 160MPa. The injector is equipped with a six-hole nozzle, where each hole has a diameter of 0.124 mm. and slightly offset to the center of the cylinder axis to allow a better cooling of the narrow bridge between the exhaust valves. The measurement system includes a blower, which supplied the intake flow rate, and a prototype single-valve direct injection diesel engine head modified to lay down the swirled-type injector. 14-bit digital CCD cameras are employed to achieve a greater level of accuracy in comparison to the results of previous measurements. The temperature field spatial distributions in the cylinder for different crank angle degrees are carried out in a single direct-injection diesel engine.

Liu, Yongfeng; Tian, Hongsen; Yang, Jianwei; Sun, Jianmin; Zhu, Aihua

2011-12-01

48

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

49

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

50

Multiresolution image representation using combined 2-D and 1-D directional filter banks.  

PubMed

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 approximation, image coding, and denoising, the proposed filter banks show visual quality improvements and have higher PSNR than the conventional separable WT or the contourlet. PMID:19095538

Tanaka, Yuichi; Ikehara, Masaaki; Nguyen, Truong Q

2009-02-01

51

Nanohole-array-based device for 2D snapshot multispectral imaging  

PubMed Central

We present a two-dimensional (2D) snapshot multispectral imager that utilizes the optical transmission characteristics of nanohole arrays (NHAs) in a gold film to resolve a mixture of input colors into multiple spectral bands. The multispectral device consists of blocks of NHAs, wherein each NHA has a unique periodicity that results in transmission resonances and minima in the visible and near-infrared regions. The multispectral device was illuminated over a wide spectral range, and the transmission was spectrally unmixed using a least-squares estimation algorithm. A NHA-based multispectral imaging system was built and tested in both reflection and transmission modes. The NHA-based multispectral imager was capable of extracting 2D multispectral images representative of four independent bands within the spectral range of 662?nm to 832?nm for a variety of targets. The multispectral device can potentially be integrated into a variety of imaging sensor systems. PMID:24005065

Najiminaini, Mohamadreza; Vasefi, Fartash; Kaminska, Bozena; Carson, Jeffrey J. L.

2013-01-01

52

Experimental determination of 2-D flame temperature fields by interferometric tomography  

Microsoft Academic Search

An optical method for measuring the 2-D temperature distribution in a horizontal plane of an asymmetric diffusion flame is studied. Using a Mach-Zehnder interferometer the method records projections of the index of refraction in the flame from eight different directions. The projection data are detected by a 1024 channel linear diode array and are then transferred to a computer which

Hans M. Hertz

1985-01-01

53

3D reconstruction of a carotid bifurcation from 2D transversal ultrasound images.  

PubMed

Visualizing and analyzing the morphological structure of carotid bifurcations are important for understanding the etiology of carotid atherosclerosis, which is a major cause of stroke and transient ischemic attack. For delineation of vasculatures in the carotid artery, ultrasound examinations have been widely employed because of a noninvasive procedure without ionizing radiation. However, conventional 2D ultrasound imaging has technical limitations in observing the complicated 3D shapes and asymmetric vasodilation of bifurcations. This study aims to propose image-processing techniques for better 3D reconstruction of a carotid bifurcation in a rat by using 2D cross-sectional ultrasound images. A high-resolution ultrasound imaging system with a probe centered at 40MHz was employed to obtain 2D transversal images. The lumen boundaries in each transverse ultrasound image were detected by using three different techniques; an ellipse-fitting, a correlation mapping to visualize the decorrelation of blood flow, and the ellipse-fitting on the correlation map. When the results are compared, the third technique provides relatively good boundary extraction. The incomplete boundaries of arterial lumen caused by acoustic artifacts are somewhat resolved by adopting the correlation mapping and the distortion in the boundary detection near the bifurcation apex was largely reduced by using the ellipse-fitting technique. The 3D lumen geometry of a carotid artery was obtained by volumetric rendering of several 2D slices. For the 3D vasodilatation of the carotid bifurcation, lumen geometries at the contraction and expansion states were simultaneously depicted at various view angles. The present 3D reconstruction methods would be useful for efficient extraction and construction of the 3D lumen geometries of carotid bifurcations from 2D ultrasound images. PMID:24965564

Yeom, Eunseop; Nam, Kweon-Ho; Jin, Changzhu; Paeng, Dong-Guk; Lee, Sang-Joon

2014-12-01

54

Parameterising root system growth models using 2D neutron radiography images  

NASA Astrophysics Data System (ADS)

Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary images by a closing and a thinning step. Then, a weighted graph is produced from this skeleton, where root tips and branch points are the nodes of the graph. For each connecting edge, the pixel coordinates are stored in a list. Finally, a root system growth model is used to determine individual roots within the graph. In this way, the sequential appearance of each sub-branch is maintained. We demonstrate the use of this algorithm to determine parameters for the root system growth model of Leitner et al. (2010). We use 2D radiography images of Lupine plants. Parameters that are gained from the images include the length of the apical and basal zones, the internodal distances, the number of branches per root, the branching angels, the root radii, and the root growth rate. Computed parameter values are means of four replicates, i.e. the means over four root systems grown under the same conditions. The root systems were classified according to their branching order, and average parameter values were determined for each root order. Based on these parameters, the dynamics of root system growth can be recaptured and analysed.

Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel

2013-04-01

55

Comparison of measured 2D ELMs with synthetic images from BOUT++ simulation in KSTAR  

NASA Astrophysics Data System (ADS)

A detailed study of edge-localized mode (ELM) dynamics in the KSTAR tokamak is performed using a two-dimensional (2D) electron cyclotron emission imaging (ECEI) diagnostic system. Highly coherent mode structures rotating in the poloidal view plane are routinely observed in the inter-ELM pedestal region where the optical thickness for ECE rapidly changes and the interpretation of emission intensity is complicated. To have confidence on the measurements, the observed images are compared with synthetic images of the ELM structure deduced from three-field BOUT++ simulations. The synthetic process considers instrumental effects of the ECEI diagnostic, intrinsic broadening of the ECE and background noise. The synthetic 2D images highly resemble the observed structure, providing confidence that the ELM dynamics can be visualized by ECEI.

Kim, M.; Choi, M. J.; Lee, J.; Yun, G. S.; Lee, W.; Park, H. K.; Domier, C. W.; Luhmann, N. C., Jr.; Xu, X. Q.; the KSTAR Team

2014-09-01

56

Digital breast tomosynthesis image reconstruction using 2D and 3D total variation minimization  

PubMed Central

Background Digital breast tomosynthesis (DBT) is an emerging imaging modality which produces three-dimensional radiographic images of breast. DBT reconstructs tomographic images from a limited view angle, thus data acquired from DBT is not sufficient enough to reconstruct an exact image. It was proven that a sparse image from a highly undersampled data can be reconstructed via compressed sensing (CS) techniques. This can be done by minimizing the l1 norm of the gradient of the image which can also be defined as total variation (TV) minimization. In tomosynthesis imaging problem, this idea was utilized by minimizing total variation of image reconstructed by algebraic reconstruction technique (ART). Previous studies have largely addressed 2-dimensional (2D) TV minimization and only few of them have mentioned 3-dimensional (3D) TV minimization. However, quantitative analysis of 2D and 3D TV minimization with ART in DBT imaging has not been studied. Methods In this paper two different DBT image reconstruction algorithms with total variation minimization have been developed and a comprehensive quantitative analysis of these two methods and ART has been carried out: The first method is ART?+?TV2D where TV is applied to each slice independently. The other method is ART?+?TV3D in which TV is applied by formulating the minimization problem 3D considering all slices. Results A 3D phantom which roughly simulates a breast tomosynthesis image was designed to evaluate the performance of the methods both quantitatively and qualitatively in the sense of visual assessment, structural similarity (SSIM), root means square error (RMSE) of a specific layer of interest (LOI) and total error values. Both methods show superior results in reducing out-of-focus slice blur compared to ART. Conclusions Computer simulations show that ART + TV3D method substantially enhances the reconstructed image with fewer artifacts and smaller error rates than the other two algorithms under the same configuration and parameters and it provides faster convergence rate. PMID:24172584

2013-01-01

57

Minimizing user intervention in registering 2D images to 3D models  

Microsoft Academic Search

This paper proposes a novel technique to speed up the registration of 2D images to 3D models. This problem often arises in the process of digitalization of real objects, because pictures are often taken independently from the 3D geometry. Although there are a number of methods to solve the prob- lem of registration automatically, they all need some further assumptions,

Thomas Franken; Matteo Dellepiane; Fabio Ganovelli; Paolo Cignoni; Claudio Montani; Roberto Scopigno

2005-01-01

58

2D and 3D ISAR image reconstruction through filtered back Timothy Ray1  

E-print Network

2D and 3D ISAR image reconstruction through filtered back projection Timothy Ray1 , Yufeng Cao1 filtered inversion scheme for turntable inverse synthetic aperture radar (ISAR) data from a scalar wave Radar (ISAR), Fourier Diffraction Theorem, Turntable ISAR, Filtered Back-Projection. 1. INTRODUCTION

Qiao, Zhijun "George" - Department of Mathematics, University of Texas

59

2D image registration using focused mutual information for application in dentistry  

E-print Network

2D image registration using focused mutual information for application in dentistry W. Jacquet a information, digital subtraction radiography, piecewise rigid, dentistry PACS: 07.05.Pj, 07.05.Rm, 87.57.-s-intervention) therapy, [(5)] or a restorative treatment (intervention). Lehmann et al. [(6)] used dental ra- diographs of

de Groen, Pieter

60

A comparison of similarity measures for use in 2D-3D medical image registration  

Microsoft Academic Search

A comparison of six similarity measures for use in intensity based 2D-3D image registration is presented. The accuracy of\\u000a the similarity measures are compared to a “gold-standard” registration which has been accurately calculated using fiducial\\u000a markers. The similarity measures are used to register a CT scan to a fluoroscopy image of a spine phantom. The registration\\u000a is carried out within

Graeme P Penney; Jiirgen Weese; John A Little; Paul Desmedt; Derek LG Hill; David J Hawkes

61

Snapshot 2D tomography via coded aperture x-ray scatter imaging.  

PubMed

This paper describes a fan beam coded aperture x-ray scatter imaging system that acquires a tomographic image from each snapshot. This technique exploits the cylindrical symmetry of the scattering cross section to avoid the scanning motion typically required by projection tomography. We use a coded aperture with a harmonic dependence to determine range and a shift code to determine cross range. Here we use a forward-scatter configuration to image 2D objects and use serial exposures to acquire tomographic video of motion within a plane. Our reconstruction algorithm also estimates the angular dependence of the scattered radiance, a step toward materials imaging and identification. PMID:23842254

MacCabe, Kenneth P; Holmgren, Andrew D; Tornai, Martin P; Brady, David J

2013-07-01

62

Estimating of fractal and correlation dimension from 2-D and 3-D images  

NASA Astrophysics Data System (ADS)

If the recursive algorithm or the dynamical system that generate the fractal shape is known, then the fractal dimension can be calculated. Many natural shapes are fractals. However, one can usually not estimate exactly the corresponding dimension from images, because the images are formed of finite amount of values at discrete points. In here, one algorithm to estimate fractal dimension and two algorithms to estimate the correlation dimension, which is a lower bound of fractal dimension, from a 2D or 3D image are introduced. The calculated dimension could be used in order to solve many practical problems. For example, one could use the dimension image on icebreakers in order to determine the type of ice and in order to find cracks in the ice using satellite images. Also one can use dimension image in image compression and in pattern recognition.

Vepsalainen, Ari M.; Ma, Jun

1989-11-01

63

Temperature-dependent structure changes in Nafion ionomer studied by PCMW2D IR correlation spectroscopy  

NASA Astrophysics Data System (ADS)

Temperature-dependent infrared (IR) spectra of a Nafion membrane were measured over a temperature range from 30 to 320 °C. The obtained spectra were analyzed using perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy and quantum chemical calculations (QCC). Three-step structural changes in Nafion ionomer induced by temperature were revealed. Dehydration of the ionomer is dominant below 60 °C. Protonation of sulfonate group in the side chain terminal occurs around 100 °C. Thermal degradation of the chains starts above 280 °C.

Morita, Shigeaki; Kitagawa, Kuniyuki

2010-06-01

64

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

PubMed

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. PMID:16266101

Rohlfing, Torsten; Russakoff, Daniel B; Denzler, Joachim; Mori, Kensaku; Maurer, Calvin R

2005-09-01

65

A Wavelet Relational Fuzzy C-Means Algorithm for 2D Gel Image Segmentation  

PubMed Central

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

66

[Comparison of two image guided radiation therapy (IGRT) methods used for prostate cancer patients--CBCT and 2D-2D kV].  

PubMed

The IGRT notion (image guided radiation therapy) comprises all techniques enabling checking and correction of patients position directly before or during an irradiation session. In last years they became a standard in radiotherapy due to decreasing of geographical misses. The aim of our study was a comparison of two IGRT techniques--CBCT and 2D-2D kV performed for prostate cancer patients and a comparison of two immobilization systems used for them. The performed analysis comprises 3582 2D-2D kV and 2110 CBCT IGRT measurements made for 85 prostate cancer patients. Patients were irradiated using thermoplastic masks and two kinds of immobilizing plates. One subgroup of patients was treated using leg supports and second one without them. Mean, maximum, minimum and standard deviation of absolute values of shifts (cm) measured using 2D-2D kV were 0.27, 0.0, 2.8 and 0.33 respectively. For CBCT these same values were 0.31, 0.0, 4.1 and 0.33. Mean, maximum, minimum and standard deviation of real shifts values (cm) measured using 2D-2D kV were -0.01, -2.5, 2.8 and 0.43 respectively. For CBCT these same values were 0.01, -4.1, 2.3 and 0.45. Comparison of shift absolute values distributions for whole analyzed group showed statistically significant difference (p=0.001) between 2D-2D kV and CBCT with higher mean for CBCT (0.31 vs 0.27) and equal standard deviations. Statistically significant difference (p=0.000...) between distributions of measurements in z axis was found (for 2D-2D kV mean 0.16, SD=0.21, for CBCT mean 0.25, SD=0.25). Comparison of absolute shifts values distributions revealed significant difference for CBCT, for two immobilization plates--in x (p=0.001) and y axis (p=0.007). For the small plate in x axis mean was 0.22 (SD=0.2), and for the large one (with an integrated head support) 0.17 (SD=0.2). Comparison of absolute shifts values for sub- groups created dependently on the leg support use, showed significant differences in x axis for 2D-2D kV (p=0.000...); mean in the subgroup irradiated without leg supports was 0.14 (SD=0.14) and for the subgroup without them was 0.19 (SD=0.15) and in x axis for CBCT (p=0.03); mean in the subgroup irradiated without leg supports was 0.18 (SD=0.18) and for the subgroup without them was 0.23 (SD=0.22). Significant difference was also revealed for the whole group of absolute shift values for 2D-2D kV (p=0.01). For the subgroup irradiated without leg supports mean was 0.27 (SD=0.34), and for the subgroup treated with them was 0.27 (SD=0.31). Obtained results permit us to conclude that in the case of prostate cancer patients IGRT based on the bone anatomy visualization, the method of choice should be 2D-2D kV, because it allows for more precise and shorter patient position evaluation and, that during IGRT of prostate cancer patients using a simple thermoplastic immobilization system is sufficient; use of more sophisticated systems with additional supports did not improve the patient immobilization. PMID:19004227

Miszczyk, Leszek; Leszczy?ski, Wojciech; Szczepanik, Krzysztof; Majewski, Wojciech

2008-01-01

67

FY2D retrieved surface temperature change as a predictor for sandstorm forecasting over Northwest China  

Microsoft Academic Search

This paper employed an index called surface temperature change (STC) for assisting the sandstorm forecasting over Northwest China. The index was retrieved from Chinese FY-2D\\/S-VISSR (Stretched - Visible and Infrared Spin-Scan Radiometer) data. For examining the accuracy of sandstorm forecasts that regard STC as a predictor or not, we applied this index to all sandstorm cases that occurred in research

Hui Han; Ni Guo; Dihua Cai; Jing Wang

2011-01-01

68

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

69

Fast 2-D soft X-ray imaging device based on micro pattern gas detector  

NASA Astrophysics Data System (ADS)

An innovative fast system for X-ray imaging has been developed at ENEA Frascati (Italy) to be used as diagnostic of magnetic plasmas for thermonuclear fusion. It is based on a pinhole camera coupled to a Micro Pattern Gas Detector (MPGD) having a Gas Electron Multiplier (GEM) as amplifying stage. This detector (2.5 cm × 2.5 cm active area) is equipped with a 2-D read-out printed circuit board with 144 pixels (12 × 12), with an electronic channel for each pixel (charge conversion, shaping, discrimination and counting). Working in photon counting mode, in proportional regime, it is able to get X-ray images of the plasma in a selectable X-ray energy range, at very high photon fluxes (106 ph s-?1mm-2 all over the detector) and high framing rate (up to 100 kHz). It has very high dynamic range, high signal to noise ratio (statistical) and large flexibility in the optical configurations (magnification and views on the plasma). The system has been tested successfully on the Frascati Tokamak Upgrade (FTU), having central electron temperature of a few keV and density of 1020 m-3, during the summer 2001, with a one-dimensional perpendicular view of the plasma. In collaboration with ENEA, the Johns Hopkins University (JHU) and Princeton Plasma Physics (PPPL), this system has been set up and calibrated in the X-ray energy range 2-8 keV and it has been installed, with a two-dimensional tangential view, on the spherical tokamak NSTX at Princeton. Time resolved X-ray images of the NSTX plasma core have been obtained. Fast acquisitions, performed up to 50 kHz of framing rate, allow the study of the plasma evolution and its magneto-hydrodynamic instabilities, while with a slower sampling (a few kHz) the curvature of the magnetic surfaces can be measured. All these results reveal the good imaging properties of this device at high time resolution, despite of the low number of pixels, and the effectiveness of the fine controlled energy discrimination.

Pacella, D.; Bellazzini, R.; Brez, A.; Pizzicaroli, G.

2003-09-01

70

Margin structure and destabilisation processes on the Ecuador margin by 2D quantitative seismic imaging  

NASA Astrophysics Data System (ADS)

We analyse multichannel seismic reflection (MCS) data collected during the SISTEUR cruise (2000) on the Nazca-north Andean convergent plate boundary in order to investigate the tectonic impact of gas hydrates and underthrusted asperities on the slope destabilization and the crustal thinning processes. We use preserved amplitude prestack depth migration method (PSDM) by considering four MCS lines, three perpendicular and one parallel to the margin. In order to get in depth, 2D quantitative image of seismic reflectors, the accuracy of the tomographic model is gradually improved by iterative corrections of the background velocity model. Close to the Carnegie ridge, the 9 km-thick oceanic crust has strong internal reflectors caused by the Galapagos hot spot activity. Through the margin, a seismic sequence composed of three acoustically strong reflectors images the top of the subducted oceanic crust, the inter-plate decollement, and the top of the upper margin. Common Image Gathers (CIG) panels are quite flat and semblance panels are around 1 on these layers. The plate interface is imaged acoustically strong, with discontinuous reflectors dipping landward from the trench, down to a maximum depth of 9-10 km below seafloor. The margin basement has been thinned seaward (less than 2km thick), broken up and uplifted. Seamounts of the Nazca oceanic crust are potential agents for basal erosion and deformation of the upper margin. On two crosscut profiles, the decollement dips seaward and strong deep reflectors beneath the upper margin indicate that a large seamount is in the process of being subducted. Shallower, the gas hydrate stability field, illustrated by bottom simulating reflectors (BSR) on seismic profiles, corresponds to a weakness zone. The triggering mechanisms of the slope failure depend on a combination of several parameters. The main one is probably an increase of the slope angle linked to the subduction of asperities like seamounts. A layer of decreased shear strength at the base of the gas hydrate stability field related to pressure or temperature change is another factor. In our study these two factors are joined.

D'Acremont, E.; Ribodetti, A.; Collot, J.; Sage, F.

2005-12-01

71

Radiometer uncertainty equation research of 2D planar scanning PMMW imaging system  

NASA Astrophysics Data System (ADS)

With advances in millimeter-wave technology, passive millimeter-wave (PMMW) imaging technology has received considerable concerns, and it has established itself in a wide range of military and civil practical applications, such as in the areas of remote sensing, blind landing, precision guidance and security inspection. Both the high transparency of clothing at millimeter wavelengths and the spatial resolution required to generate adequate images combine to make imaging at millimeter wavelengths a natural approach of screening people for concealed contraband detection. And at the same time, the passive operation mode does not present a safety hazard to the person who is under inspection. Based on the description to the design and engineering implementation of a W-band two-dimensional (2D) planar scanning imaging system, a series of scanning methods utilized in PMMW imaging are generally compared and analyzed, followed by a discussion on the operational principle of the mode of 2D planar scanning particularly. Furthermore, it is found that the traditional radiometer uncertainty equation, which is derived from a moving platform, does not hold under this 2D planar scanning mode due to the fact that there is no absolute connection between the scanning rates in horizontal direction and vertical direction. Consequently, an improved radiometer uncertainty equation is carried out in this paper, by means of taking the total time spent on scanning and imaging into consideration, with the purpose of solving the problem mentioned above. In addition, the related factors which affect the quality of radiometric images are further investigated under the improved radiometer uncertainty equation, and ultimately some original results are presented and analyzed to demonstrate the significance and validity of this new methodology.

Hu, Taiyang; Xu, Jianzhong; Xiao, Zelong

2009-07-01

72

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

73

Mid-IR hyperspectral imaging of laminar flames for 2-D scalar values.  

PubMed

This work presents a new emission-based measurement which permits quantification of two-dimensional scalar distributions in laminar flames. A Michelson-based Fourier-transform spectrometer coupled to a mid-infrared camera (1.5 ?m to 5.5 ?m) obtained 256 × 128pixel hyperspectral flame images at high spectral (??? = 0.75cm-1) and spatial (0.52 mm) resolutions. The measurements revealed line and band emission from H2O, CO2, and CO. Measurements were collected from a well-characterized partially-premixed ethylene (C2H4) flame produced on a Hencken burner at equivalence ratios, ?, of 0.8, 0.9, 1.1, and 1.3. After describing the instrument and novel calibration methodology, analysis of the flames is presented. A single-layer, line-by-line radiative transfer model is used to retrieve path-averaged temperature, H2O, CO2 and CO column densities from emission spectra between 2.3 ?m to 5.1 ?m. The radiative transfer model uses line intensities from the latest HITEMP and CDSD-4000 spectroscopic databases. For the ? = 1.1 flame, the spectrally estimated temperature for a single pixel 10 mm above burner center was T = (2318 ± 19)K, and agrees favorably with recently reported laser absorption measurements, T = (2348 ± 115)K, and a NASA CEA equilibrium calculation, T = 2389K. Near the base of the flame, absolute concentrations can be estimated, and H2O, CO2, and CO concentrations of (12.5 ± 1.7) %, (10.1 ± 1.0) %, and (3.8 ± 0.3) %, respectively, compared favorably with the corresponding CEA values of 12.8%, 9.9% and 4.1%. Spectrally-estimated temperatures and concentrations at the other equivalence ratios were in similar agreement with measurements and equilibrium calculations. 2-D temperature and species column density maps underscore the ?-dependent chemical composition of the flames. The reported uncertainties are 95% confidence intervals and include both statistical fit errors and the propagation of systematic calibration errors using a Monte Carlo approach. Systematic errors could warrant a factor of two increase in reported uncertainties. This work helps to establish IFTS as a valuable combustion diagnostic tool. PMID:25321539

Rhoby, Michael R; Blunck, David L; Gross, Kevin C

2014-09-01

74

Image Denoising With 2D Scale-Mixing Complex Wavelet Transforms.  

PubMed

This paper introduces an image denoising procedure based on a 2D scale-mixing complex-valued wavelet transform. Both the minimal (unitary) and redundant (maximum overlap) versions of the transform are used. The covariance structure of white noise in wavelet domain is established. Estimation is performed via empirical Bayesian techniques, including versions that preserve the phase of the complex-valued wavelet coefficients and those that do not. The new procedure exhibits excellent quantitative and visual performance, which is demonstrated by simulation on standard test images. PMID:25312931

Remenyi, Norbert; Nicolis, Orietta; Nason, Guy; Vidakovic, Brani

2014-12-01

75

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. PMID:18401460

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

2008-01-01

76

Deep Tissue Photoacoustic Imaging Using a Miniaturized 2-D Capacitive Micromachined Ultrasonic Transducer Array  

PubMed Central

In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 µm), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 µm. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI. PMID:22249594

Kothapalli, Sri-Rajasekhar; Ma, Te-Jen; Vaithilingam, Srikant; Oralkan, Omer

2014-01-01

77

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

78

High-frame-rate 2-D vector blood flow imaging in the frequency domain.  

PubMed

Conventional ultrasound Doppler techniques estimate the blood velocity exclusively in the axial direction to produce the sonograms and color flow maps needed for diagnosis of cardiovascular diseases. In this paper, a novel method to produce bi-dimensional maps of 2-D velocity vectors is proposed. The region of interest (ROI) is illuminated by plane waves transmitted at the pulse repetition frequency (PRF) in a fixed direction. For each transmitted plane wave, the backscattered echoes are recombined offline to produce the radio-frequency image of the ROI. The local 2-D phase shifts between consecutive speckle images are efficiently estimated in the frequency domain, to produce vector maps up to 15 kHz PRF. Simulations and in vitro steady-flow experiments with different setup conditions have been conducted to thoroughly evaluate the method's performance. Bias is proved to be lower than 10% in most simulations and lower than 20% in experiments. Further simulations and in vivo experiments have been made to test the approach's feasibility in pulsatile flow conditions. It has been estimated that the computation of the frequency domain algorithm is more than 50 times faster than the computation of the reference 2-D cross-correlation algorithm. PMID:25167150

Lenge, Matteo; Ramalli, Alessandro; Boni, Enrico; Liebgott, Hervé; Cachard, Christian; Tortoli, Piero

2014-09-01

79

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

80

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

81

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

82

Translational and rotational temperatures of a 2D vibrated granular gas in microgravity  

E-print Network

We present an experimental study performed on a vibrated granular gas enclosed into a 2D rectangular cell. Experiments are realized in microgravity. High speed video recording and optical tracking allow to obtain the full kinematics (translation and rotation) of the particles. The inelastic parameters are retrieved from the experimental trajectories as well as the translational and rotational velocity distributions. We report that the experimental ratio of translational versus rotational temperature decreases to the density of the medium but increases with the driving velocity of the cell. These experimental results are compared with existing theories and we point out the differences observed. We also present a model which fairly predicts the equilibrium experimental temperatures along the direction of vibration.

Yan Grasselli; Georges Bossis; Romain Morini

2014-03-19

83

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

84

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

85

AIDA: a software package for 2D model fitting analysis of astronomical images  

NASA Astrophysics Data System (ADS)

AIDA (Astronomical Image Decomposition and Analysis) is a software package originally developed to analyze images of galaxies with a bright nucleus and to perform the decomposition into the nuclear and the galaxy components. The package is able to perform photometrical and morphological study of faint galaxies as well as standard photometry of stellar fields. With the use of graphical interfaces, AIDA assists interactively the user in selecting sources and preparing them for the analysis. Since the decomposition into the galactic and nuclear components, in particular in the case where the nucleus is dominant, requires a careful characterization of the PSF, AIDA has been designed to manage complex 2-D models (both analytical and empirical, or a combinations of them), even variable in the field of view, making it suitable for Adaptive Optics observations. PSF models can be provided by the user or modeled by AIDA itself using reference stars in the images. Relevant parameters of the target sources are then extracted by fitting source models convolved with the PSF. In addition to the standard (interactive) mode AIDA can also perform automatic processing of a large numbers of images, extracting the PSF model from each image and evaluating source parameters for targets (stars, galaxies, AGN or QSO) by model fitting. With this automatic mode, AIDA can process, in a fully automatic way, large datasets of targets distributed in several images.

Uslenghi, Michela; Falomo, Renato

2011-09-01

86

Modeling ECM Fiber Formation: Structure Information Extracted by Analysis of 2D and 3D Image Sets  

E-print Network

Modeling ECM Fiber Formation: Structure Information Extracted by Analysis of 2D and 3D Image Sets of extracellular matrix (ECM) are highly correlated to its structure. Understanding this fibrous structure is very to analyze the structural properties of ECM. We describe a two-dimensional (2-D) fiber middle- line tracing

Hoffmann, Christoph M.

87

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

E-print Network

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 ...

Rinnerbauer, V.

88

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

E-print Network

We provide a systematic characterization of the nanosecond ground-state lactam-lactim tautomerization of pyridine derivatives in aqueous solution under ambient conditions using temperature-jump transient 2D IR spectroscopy. ...

Peng, Chunte Sam

89

From 2D to 3D: II. TEM and AFM Images  

NSDL National Science Digital Library

The problems in the accompanying exercises, "From 2D to 3D: Escher drawings", deal with abstractions that can be related to minerals through geometrical features they have in common. However, we are utimately interested in real minerals, their symmetries, and complexities. High-resolution transmission electron microscopy (HRTEM) provides 2-D projections of mineral structures at almost the atomic scale, and atomic force microscopy (AFM) provides 3-D information about the surfaces of minerals. By using these instruments, we can learn about defects in minerals and their complexities. The mineral examples in this problem set include representatives from several silicate structure type, sulfides, a sulfosalt, and a carbonate. Interpretation of the images is less clear-cut than of the idealized drawings. In some cases the results can be ambiguous, but the provide a scope for fruitful discussions among class members. In a few cases, references are given to the published papers from which the images are taken. These can be used to draw students into the professional literature, even though it will not always be possible to arrive at unambiguous answers. These problems should be thought provoking and yet manageable at several levels of complexity.

90

What shape are dolphins? Building 3D morphable models from 2D images.  

PubMed

3D morphable models are low-dimensional parameterizations of 3D object classes which provide a powerful means of associating 3D geometry to 2D images. However, morphable models are currently generated from 3D scans, so for general object classes such as animals they are economically and practically infeasible. We show that, given a small amount of user interaction (little more than that required to build a conventional morphable model), there is enough information in a collection of 2D pictures of certain object classes to generate a full 3D morphable model, even in the absence of surface texture. The key restriction is that the object class should not be strongly articulated, and that a very rough rigid model should be provided as an initial estimate of the “mean shape.” The model representation is a linear combination of subdivision surfaces, which we fit to image silhouettes and any identifiable key points using a novel combined continuous-discrete optimization strategy. Results are demonstrated on several natural object classes, and show that models of rather high quality can be obtained from this limited information. PMID:22392707

Cashman, Thomas J; Fitzgibbon, Andrew W

2013-01-01

91

Groundwater Exploration Using 2-D Resistivity Imaging Technique in Marang, Terengganu, Malaysia  

NASA Astrophysics Data System (ADS)

Surface water is critically important in supplying water to streams and wetlands, and in providing water for irrigation, manufacturing, electricity power and other uses and it is an important source of water supply especially in various regions in Malaysia and it become ever more important with an increasing population. However groundwater can be an alternative source of water to the ever increasing population. Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic water formations. This would provide alternative freshwater source. In order to determine the existence of usable groundwater for agriculture purposes in Marang Terengganu, 2-D resistivity imaging technique was utilized. Three lines were surveyed at the site. The 2-D resistivity imaging technique utilized the Pole -dipole array because of relatively good horizontal coverage but it has significantly higher signal strength. The total length of the survey lines is 400 meters. Three lines were surveyed for groundwater delineation purpose. At Marang, the survey site shows the existence of groundwater. The maximum depth of investigations for the surveys is 125 meters. In general the results show that the subsurface is made up of sand and clay (resistivity value of less 100 ohm-m) and sandstone with resistivity of more than 2000 ohm-m in all the sections. This zone can be a source of groundwater.

Kadri, Muhammad; Nawawi, M. N. M.

2010-07-01

92

Groundwater exploration using 2D Resistivity Imaging in Pagoh, Johor, Malaysia  

NASA Astrophysics Data System (ADS)

Groundwater is a very important component of water resources in nature. Since the demand of groundwater increases with population growth, it is necessary to explore groundwater more intensively. In Malaysia only less than 2% of the present water used is developed from groundwater. In order to determine the existence of usable groundwater for irrigation and drinking purposes in Pagoh, 2D resistivity imaging technique was utilized. The 2-D resistivity imaging technique utilized the Wenner—Schlumberger electrode array configuration because this array is moderately sensitive to both horizontal and vertical structures. Three lines were surveyed for groundwater delineation purpose The length for each survey lines are 400 meters. At Pagoh, the survey site shows the existence of groundwater. It is indicated by the resistivity values about 10-100 ohm-m. The maximum depth of investigation survey is 77 meters. In general the results show that the subsurface is made up of alluvium and clay and the high resistivity values of more than 1000 ohm-m near the surface is due laterite and the end of the depth can be interpreted as mixture of weathered material or bedrock.

Kadri, Muhammad; Nawawi, M. N. M.

2010-12-01

93

2D surface temperature measurement of plasma facing components with modulated active pyrometry  

NASA Astrophysics Data System (ADS)

In nuclear fusion devices, such as Tore Supra, the plasma facing components (PFC) are in carbon. Such components are exposed to very high heat flux and the surface temperature measurement is mandatory for the safety of the device and also for efficient plasma scenario development. Besides this measurement is essential to evaluate these heat fluxes for a better knowledge of the physics of plasma-wall interaction, it is also required to monitor the fatigue of PFCs. Infrared system (IR) is used to manage to measure surface temperature in real time. For carbon PFCs, the emissivity is high and known (? ˜ 0.8), therefore the contribution of the reflected flux from environment and collected by the IR cameras can be neglected. However, the future tokamaks such as WEST and ITER will be equipped with PFCs in metal (W and Be/W, respectively) with low and variable emissivities (? ˜ 0.1-0.4). Consequently, the reflected flux will contribute significantly in the collected flux by IR camera. The modulated active pyrometry, using a bicolor camera, proposed in this paper allows a 2D surface temperature measurement independently of the reflected fluxes and the emissivity. Experimental results with Tungsten sample are reported and compared with simultaneous measurement performed with classical pyrometry (monochromatic and bichromatic) with and without reflective flux demonstrating the efficiency of this method for surface temperature measurement independently of the reflected flux and the emissivity.

Amiel, S.; Loarer, T.; Pocheau, C.; Roche, H.; Gauthier, E.; Aumeunier, M.-H.; Le Niliot, C.; Rigollet, F.; Courtois, X.; Jouve, M.; Balorin, C.; Moncada, V.

2014-10-01

94

2D surface temperature measurement of plasma facing components with modulated active pyrometry.  

PubMed

In nuclear fusion devices, such as Tore Supra, the plasma facing components (PFC) are in carbon. Such components are exposed to very high heat flux and the surface temperature measurement is mandatory for the safety of the device and also for efficient plasma scenario development. Besides this measurement is essential to evaluate these heat fluxes for a better knowledge of the physics of plasma-wall interaction, it is also required to monitor the fatigue of PFCs. Infrared system (IR) is used to manage to measure surface temperature in real time. For carbon PFCs, the emissivity is high and known (? ? 0.8), therefore the contribution of the reflected flux from environment and collected by the IR cameras can be neglected. However, the future tokamaks such as WEST and ITER will be equipped with PFCs in metal (W and Be/W, respectively) with low and variable emissivities (? ? 0.1-0.4). Consequently, the reflected flux will contribute significantly in the collected flux by IR camera. The modulated active pyrometry, using a bicolor camera, proposed in this paper allows a 2D surface temperature measurement independently of the reflected fluxes and the emissivity. Experimental results with Tungsten sample are reported and compared with simultaneous measurement performed with classical pyrometry (monochromatic and bichromatic) with and without reflective flux demonstrating the efficiency of this method for surface temperature measurement independently of the reflected flux and the emissivity. PMID:25362442

Amiel, S; Loarer, T; Pocheau, C; Roche, H; Gauthier, E; Aumeunier, M-H; Le Niliot, C; Rigollet, F; Courtois, X; Jouve, M; Balorin, C; Moncada, V

2014-10-01

95

Parallelization of the 2D fast wavelet transform with a space-filling curve image scan  

NASA Astrophysics Data System (ADS)

The classical raster (i.e. row by row) image scan does not match the data processing flow, internal to the pyramid structure obtained by the 2D fast wavelet transform of a 2N X 2N image with a (2(gamma ) + 1) X (2(gamma ) + 1) mother wavelet, therefore introducing large latencies, important memory requirements, and irregular processor activities in parallelized implementations. A new algorithm is proposed in which all image data are scanned following a fractal, space-filling curve, which, compared to the raster image scan, offers the following advantages: i) it reduces the calculation memory with almost a factor 2, while maintaining a simple address calculation scheme, ii) the latency in the first N-(gamma) -3 levels of the pyramid, which contain a high percentage of the pyramid data, is minimized, leading to improved block-oriented post-processing capabilities (e.g. vector quantization for image compression), iii) the calculations are spread out more uniformly over one frame slot, and iv) the process is naturally subdivided into similar subproblems, increasing the granularity of the algorithm, without introducing severe communication bottle-necks for parallel architectures.

Lafruit, Gauthier; Cornelis, Jan P.

1995-08-01

96

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. PMID:23480874

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

2013-01-01

97

DATA FUSION IN 2D AND 3D IMAGE PROCESSING: AN OVERVIEW Isabelle BLOCH, Henri MA^ITRE  

E-print Network

DATA FUSION IN 2D AND 3D IMAGE PROCESSING: AN OVERVIEW Isabelle BLOCH, Henri MA^ITRE Ecole of the art in image fusion, with an emphasis on the emergence of new techniques, often issued from other the aim of data fusion and its speci city when image informationhas to be combined, with emphasis

98

A Synthesis of 3-D Kabuki Face from Ancient 2-D Images Using Multilevel Radial Basis Function  

Microsoft Academic Search

A technique to synthesize a 3-D Kabuki face model from ancient images is proposed. Kabuki is a traditional Japanese theater art. Kabuki researchers can know some ancient information of Kabuki from the ancient 2-D images such as Ukiyo-e (Japanese drawing) and Kumadori images (Kabuki makeup). Compared with the real face images in photographs and paintings, the face images in Ukiyo-e

Xin Yin; Weiwei Xu; Ryo Akama; Hiromi T. Tanaka

2008-01-01

99

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

100

The concept of 2D gated imaging for particle sizing in a laminar diffusion flame  

NASA Astrophysics Data System (ADS)

In this work, time-resolved laser-induced incandescence (TiRe LII) has been employed to measure primary particle diameters of soot in an atmospheric laminar ethylene diffusion flame. The generated data set complements existing data determined in one single location and takes advantage of the good spatial resolution of the ICCD detection. Time resolution is achieved by shifting the camera gate along the LII decay. One key input parameter for the analysis of time-resolved LII is the local flame temperature. This was determined on a grid throughout the flame by coherent anti-Stokes Raman scattering. The accurate temperature data, in combination with other published data from this flame, are well suited for soot model validation purposes while we showed feasibility of a shifted gate approach to deduce 2D particle sizes in the chosen standard flame.

Hadef, Redjem; Geigle, Klaus Peter; Zerbs, Jochen; Sawchuk, Robert A.; Snelling, David R.

2013-09-01

101

2-D fluorescence lifetime imaging using a 10kHz\\/150-ps gated image intensifier  

Microsoft Academic Search

Summary form only given. Fluorescence Lifetime Imaging (FLIM) is a promising technique to provide noninvasive functional\\/diagnostic imaging in biological tissue because it does not require quantitative intensity measurements\\/wavelength ratiometric probes and can exploit the sensitivity of fluorescence lifetime to the environmental changes in ion (e.g. Ca\\/sup 2+\\/) concentration, pH, etc. To date, however, we are aware of no commercially available

K. Dowling; S. C. W. Hyde; J. C. Dainty; P. M. W. French; J. D. Hares

1996-01-01

102

Velocimetry Analysis of 2D Turbulence Imaging Data from Beam Emission Spectroscopy  

NASA Astrophysics Data System (ADS)

The time-resolved velocity field of density fluctuations contains pertinent dynamics on critical features of plasma turbulence, including zonal flow and geodesic acoustic mode behavior, and the ExB motion from underlying electrostatic potential fluctuations. This velocity field may be used to infer the Reynolds stress (d/dr), thought to drive zonal flows, and the radial turbulent particle flux. The beam emission spectroscopy (BES) system on DIII-D obtains radially and poloidally resolved images (up to 8x8) of density fluctuations at ˜1 cm resolution. The orthogonal dynamic programming method, developed in fluid dynamics, is used to extract the 2D flow field, v(r,z,t) from the fluctuating densities. A vector-matching method determines structure motion from one frame to another. The technique will also be applied to density data from nonlinear GYRO simulations of turbulence, using an appropriate BES synthetic diagnostic. The inferred 2D density fluctuation velocity field will be compared with the ExB fluctuations also calculated from GYRO to discern their relationship and wavenumber sensitivity.

McKee, G. R.; Fonck, R. J.; Yan, Z.; Holland, C.

2012-10-01

103

Comparison of 2D temperature maps recorded during laser-induced thermal tissue treatment with corresponding temperature distributions calculated from 3D Monte-Carlo simulations  

NASA Astrophysics Data System (ADS)

Minimally invasive techniques often require special biomedical monitoring schemes. In the case of laser coagulation of tumors accurate temperature mapping is desirable for therapy control. While magnetic resonance (MR)-based thermometry can easily yield qualitative results it is still difficult to calibrate this technique with independent temperature probes for the entire 2D field of view. Calculated temperature maps derived from Monte-Carlo simulations (MCS), on the other hand, are suitable for therapy planning and dosimetry but typically can not account for the extract individual tissue parameters and physiological changes upon heating. In this work, online thermometry was combined with MCS techniques to explore the feasibility and potential of such a biomodal approach for surgical assist systems. For the first time, the result of a 3D simulation were evaluated with MR techniques. An MR thermometry system was used to monitor the temperature evolution during laser-induced thermal treatment of bovine liver using a commercially available water-cooled applicator. A systematic comparison between MR-derived 2D temperature maps in different orientations and corresponding snapshots of a 3D MCS of the laser-induced processes is presented. The MCS is capable of resolving the complex temperature patterns observed in the MR-derived images and yields a good agreement with respect to absolute temperatures and damage volume dimensions. The observed quantitative agreement is around 10 degrees C and on the order of 10 percent, respectively. The integrated simulation-and-monitoring approach has the potential to improve surgical assistance during thermal interventions.

Busse, Harald; Bublat, Martin; Ratering, Ralf; Rassek, Margarethe; Schwarzmaier, Hans-Joachim; Kahn, Thomas

2000-05-01

104

Assessment of Prosthesis Alignment after Revision Total Knee Arthroplasty Using EOS 2D and 3D Imaging: A Reliability Study  

PubMed Central

Introduction A new low-dose X-ray device, called EOS, has been introduced for determining lower-limb alignment in 2D and 3D. Reliability has not yet been assessed when using EOS on lower limbs containing a knee prosthesis. Therefore purpose of this study was to determine intraobserver and interobserver reliability of EOS 2D and 3D knee prosthesis alignment measurements after revision total knee arthroplasty (rTKA). Methods Forty anteroposterior and lateral images of 37 rTKA patients were included. Two observers independently performed measurements on these images twice. Varus/valgus angles were measured in 2D (VV2D) and 3D (VV3D). Intraclass correlation coefficients and the Bland and Altman method were used to determine reliability. T-tests were used to test potential differences. Results Intraobserver and interobserver reliability were excellent for VV2D and VV3D. No significant difference or bias between the first and second measurements or the two observers was found. A significant mean and absolute difference of respectively 1.00° and 1.61° existed between 2D and 3D measurements. Conclusions EOS provides reliable varus/valgus measurements in 2D and 3D for the alignment of the knee joint with a knee prosthesis. However, significant differences exist between varus/valgus measurements in 2D and 3D. PMID:25247714

Meijer, Marrigje F.; Boerboom, Alexander L.; Stevens, Martin; Bulstra, Sjoerd K.; Reininga, Inge H. F.

2014-01-01

105

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

106

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

107

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

108

Clinical applications of 2D and 3D CT imaging of the airways--a review.  

PubMed

Hardware and software evolution has broadened the possibilities of 2D and 3D reformatting of spiral CT and MR data set. In the study of the thorax, intrinsic benefits of volumetric CT scanning and better quality of reconstructed images offer us the possibility to apply additional rendering techniques to everyday clinical practice. Considering the large number and redundancy of possible post-processing imaging techniques that we can apply to raw CT sections data, it is necessary to precisely set a well-defined number of clinical applications of each of them, by careful evaluation of their benefits and possible pitfalls in each clinical setting. In diagnostic evaluation of pathological processes affecting the airways, a huge number of thin sections is necessary for detailed appraisal and has to be evaluated, and information must then be transferred to referring clinicians. By additional rendering it is possible to make image evaluation and data transfer easier, faster, and more effective. In the study of central airways, additional rendering can be of interest for precise evaluation of the length, morphology, and degree of stenoses. It may help in depicting exactly the locoregional extent of central tumours by better display of relations with bronchovascular interfaces and can increase CT/bronchoscopy sinergy. It may allow closer radiotherapy planning and better depiction of air collections, and, finally, it could ease panoramic evaluation of the results of dynamic or functional studies, that are made possible by increased speed of spiral scanning. When applied to the evaluation of peripheral airways, as a completion to conventional HRCT scans, High-Resolution Volumetric CT, by projection slabs applied to target areas of interest, can better depict the profusion and extension of affected bronchial segments in bronchiectasis, influence the choice of different approaches for tissue sampling by better evaluation of the relations of lung nodules with the airways, or help to detect otherwise overlooked slight pathological findings. In the exploration of the air-spaces of the head and neck, targeted multiplanar study can now be performed without additional scanning by retro-reconstructed sections from original transverse CT slices. Additional rendering can help in surgical planning, by simulation of surgical approaches, and allows better integration with functional paranasal sinuses endoscopic surgery, by endoscopic perspective rendering. Whichever application we perform, the clinical value of 2D and 3D rendering techniques lies in the possibility of overcoming perceptual difficulties and 'slice pollution', by easing more efficient data transfer without loss of information. 3D imaging should not be considered, in the large majority of cases, as a diagnostic tool: looking at reformatted images may increase diagnostic accuracy in only very few cases, but an increase in diagnostic confidence could be not negligible. The purpose of the radiologist skilled in post-processing techniques should be that of modifying patient management, by more confident diagnostic evaluation, in a small number of patients, and, in a larger number of cases, by simplifying communication with referring physicians and surgeons. We will display in detail possible clinical applications of the different 2D and 3D imaging techniques, in the study of the tracheobronchial tree, larynx, nasal cavities and paranasal sinuses by Helical CT, review relating bibliography, and briefly discuss pitfalls and perspectives of CT rendering techniques for each field. PMID:10802203

Salvolini, L; Bichi Secchi, E; Costarelli, L; De Nicola, M

2000-04-01

109

A finite-difference model to predict 2D depletion profiles arising from high temperature oxidation of alloys  

Microsoft Academic Search

ODIN is a 2-D finite-difference diffusion\\/interdiffusion computer model capable of predicting the solute depletion profiles evolved in binary and ternary alloys due to high temperature oxidation. The 2-D geometries that can be analysed include corners, rectangular edges and rib features. Empirical mass gain kinetics in the form of a general power law are employed as a boundary condition to define

W. M. Pragnell; H. E. Evans

2006-01-01

110

Black-Blood Multicontrast Imaging of Carotid Arteries with DANTE-prepared 2D and 3D MR Imaging.  

PubMed

Purpose To prospectively compare the black-blood ( BB black blood ) imaging efficiency of a delay alternating with nutation for tailored excitation ( DANTE delay alternating with nutation for tailored excitation ) preparation module with conventional double inversion-recovery ( DIR double inversion recovery ) and motion-sensitive driven equilibrium ( MSDE motion-sensitive driven equilibrium ) preparation modules and to introduce a new three-dimensional ( 3D three-dimensional ) T1-weighted magnetic resonance (MR) imaging sequence. Materials and Methods Carotid artery wall imaging was performed in 10 healthy volunteers and 15 patients in accordance with an institutional review board-approved protocol. Two-dimensional ( 2D two-dimensional ) turbo spin-echo ( TSE turbo spin echo ) and 3D three-dimensional fast low-angle shot ( FLASH fast low-angle shot ) sequences served as readout modules. DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted 2D two-dimensional TSE turbo spin echo images, as well as T1-weighted 3D three-dimensional DANTE delay alternating with nutation for tailored excitation -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional DASH DANTE-prepared FLASH ) images, were acquired in the region of the carotid artery bifurcation. For comparison, 2D two-dimensional DIR double inversion recovery -prepared, 2D two-dimensional MSDE motion-sensitive driven equilibrium -prepared multicontrast TSE turbo spin echo , and 3D three-dimensional MSDE motion-sensitive driven equilibrium -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional MERGE MSDE-prepared FLASH ) MR images were also acquired. The effective contrast-to-noise ratio ( CNReff effective contrast-to-noise ratio ) per unit time was calculated for all sequences. Paired t tests were performed to test within-group differences in vessel wall CNReff effective contrast-to-noise ratio . Results The CNReff effective contrast-to-noise ratio of DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted sequences was 27.3, 14.7, and 25.7 mm(-1)min(-1/2), respectively; this represented an improvement of approximately 25%-100% (P < .05) when compared with the CNReff effective contrast-to-noise ratio attained with existing methods. The 3D three-dimensional DASH DANTE-prepared FLASH technique proved to be a fast (<2 seconds per section) and high-spatial-resolution (0.6 mm isotropic) BB black blood technique with higher (75%-100% improvement, P < .001) signal-to-noise ratio efficiency than the 3D three-dimensional MERGE MSDE-prepared FLASH technique. Conclusion The DANTE delay alternating with nutation for tailored excitation -prepared multicontrast 2D two-dimensional BB black blood technique is a promising new tool for MR imaging of carotid artery walls. Additionally, the 3D three-dimensional DASH DANTE-prepared FLASH sequence enables 3D three-dimensional high-spatial-resolution fast T1-weighted imaging of carotid artery walls. ©RSNA, 2014 Online supplemental material is available for this article . PMID:24918958

Li, Linqing; Chai, Joshua T; Biasiolli, Luca; Robson, Matthew D; Choudhury, Robin P; Handa, Ashok I; Near, Jamie; Jezzard, Peter

2014-11-01

111

From 2D Images to 3D Tangible Models: Autostereoscopic and Haptic Visualization of Martian Rocks in Virtual Environments  

Microsoft Academic Search

A planetary rover acquires a large collection of images while exploring its surrounding environment. For example, 2D stereo images of the Martian surface captured by the lander and the Sojourner rover during the Mars Pathfinder mission in 1997 were transmitted to Earth for scientific analysis and navigation planning. Due to the limited memory and computational power of the Sojourner rover,

Cagatay Basdogan

2007-01-01

112

Crystallographic Image Processing with Unambiguous 2D Bravais Lattice Identification on the Basis of a Geometric Akaike Information Criterion  

NASA Astrophysics Data System (ADS)

Crystallographic image processing (CIP) is a technique first used to aid in the structure determination of periodic organic complexes imaged with a high-resolution transmission electron microscope (TEM). The technique has subsequently been utilized for TEM images of inorganic crystals, scanning TEM images, and even scanning probe microscope (SPM) images of two-dimensional periodic arrays. We have written software specialized for use on such SPM images. A key step in the CIP process requires that an experimental image be classified as one of only 17 possible mathematical plane symmetry groups. The current methods used for making this symmetry determination are not entirely objective, and there is no generally accepted method for measuring or quantifying deviations from ideal symmetry. Here, we discuss the crystallographic symmetries present in real images and the general techniques of CIP, with emphasis on the current methods for symmetry determination in an experimental 2D periodic image. The geometric Akaike information criterion (AIC) is introduced as a viable statistical criterion for both quantifying deviations from ideal symmetry and determining which 2D Bravais lattice best fits the experimental data from an image being processed with CIP. By objectively determining the statistically favored 2D Bravais lattice, the determination of plane symmetry in the CIP procedure can be greatly improved. As examples, we examine scanning tunneling microscope images of 2D molecular arrays of the following compounds: cobalt phthalocyanine on Au (111) substrate; nominal cobalt phthalocyanine on Ag (111); tetraphenoxyphthalocyanine on highly oriented pyrolitic graphite; hexaazatriphenylene-hexacarbonitrile on Ag (111). We show that the geometric AIC procedure can unambiguously determine which 2D Bravais lattice fits the experimental data for a variety of different lattice types. In some cases, the geometric AIC procedure can be used to determine which plane symmetry group best fits the experimental data, when traditional CIP methods fail to do so.

Bilyeu, Taylor Thomas

113

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

114

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

115

Sparse Matrix Beamforming and Image Reconstruction for 2-D HIFU Monitoring Using Harmonic Motion Imaging for Focused Ultrasound (HMIFU) With In Vitro Validation.  

PubMed

Harmonic motion imaging for focused ultrasound (HMIFU) utilizes an amplitude-modulated HIFU beam to induce a localized focal oscillatory motion simultaneously estimated. The objective of this study is to develop and show the feasibility of a novel fast beamforming algorithm for image reconstruction using GPU-based sparse-matrix operation with real-time feedback. In this study, the algorithm was implemented onto a fully integrated, clinically relevant HMIFU system. A single divergent transmit beam was used while fast beamforming was implemented using a GPU-based delay-and-sum method and a sparse-matrix operation. Axial HMI displacements were then estimated from the RF signals using a 1-D normalized cross-correlation method and streamed to a graphic user interface with frame rates up to 15 Hz, a 100-fold increase compared to conventional CPU-based processing. The real-time feedback rate does not require interrupting the HIFU treatment. Results in phantom experiments showed reproducible HMI images and monitoring of 22 in vitro HIFU treatments using the new 2-D system demonstrated reproducible displacement imaging, and monitoring of 22 in vitro HIFU treatments using the new 2-D system showed a consistent average focal displacement decrease of 46.7 ±14.6% during lesion formation. Complementary focal temperature monitoring also indicated an average rate of displacement increase and decrease with focal temperature at 0.84±1.15%/(°)C, and 2.03±0.93%/(°)C , respectively. These results reinforce the HMIFU capability of estimating and monitoring stiffness related changes in real time. Current ongoing studies include clinical translation of the presented system for monitoring of HIFU treatment for breast and pancreatic tumor applications. PMID:24960528

Hou, Gary Y; Provost, Jean; Grondin, Julien; Wang, Shutao; Marquet, Fabrice; Bunting, Ethan; Konofagou, Elisa E

2014-11-01

116

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

E-print Network

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 ...

Jones, K. C.

117

A 2D MTF approach to evaluate and guide dynamic imaging developments  

PubMed Central

As the number and complexity of partially sampled dynamic imaging methods continue to increase, reliable strategies to evaluate performance may prove most useful. In the present work, an analytical framework to evaluate given reconstruction methods is presented. A perturbation algorithm allows the proposed evaluation scheme to perform robustly without requiring knowledge about the inner workings of the method being evaluated. A main output of the evaluation process consists of a 2D modulation transfer function (MTF), an easy-to-interpret visual rendering of a method’s ability to capture all combinations of spatial and temporal frequencies. Approaches to evaluate noise properties and artifact content at all spatial and temporal frequencies are also proposed. One fully sampled phantom and three fully sampled cardiac cine datasets were subsampled (R=4 and 8), and reconstructed with the different methods tested here. A hybrid method, which combines the main advantageous features observed in our assessments, was proposed and tested in a cardiac cine application, with acceleration factors of 3.5 and 6.3 (skip factor of 4 and 8, respectively). This approach combines features from methods such as k-t sensitivity-encoding (k-t SENSE), unaliasing by Fourier encoding the overlaps in the temporal dimension-SENSE (UNFOLD-SENSE), generalized autocalibrating partially parallel acquisition (GRAPPA), sensitivity profiles from an array of coils for encoding and reconstruction in parallel (SPACE-RIP), self, hybrid referencing with UNFOLD and GRAPPA (SHRUG) and GRAPPA-enhanced sensitivity maps for SENSE reconstructions (GEYSER). PMID:19877276

Chao, Tzu-Cheng; Chung, Hsiao-Wen; Hoge, W. Scott; Madore, Bruno

2010-01-01

118

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

119

Application of conformal map theory for design of 2-D ultrasonic array structure for NDT imaging application: a feasibility study.  

PubMed

Two-dimensional ultrasonic phased arrays are becoming increasingly popular in nondestructive evaluation (NDE). Sparse array element configurations are required to fully exploit the potential benefits of 2-D phased arrays. This paper applies the conformal mapping technique as a means of designing sparse 2-D array layouts for NDE applications. Modeling using both Huygens' field prediction theory and 2-D fast Fourier transformation is employed to study the resulting new structure. A conformal power map was used that, for fixed beam width, was shown in simulations to have a greater contrast than rectangular or random arrays. A prototype aperiodic 2-D array configuration for direct contact operation in steel, with operational frequency ~3 MHz, was designed using the array design principle described in this paper. Experimental results demonstrate a working sparse-array transducer capable of performing volumetric imaging. PMID:24569253

Ramadas, Sivaram N; Jackson, Joseph C; Dziewierz, Jerzy; O'Leary, Richard; Gachagan, Anthony

2014-03-01

120

An influence of solar activity on latitudinal distribution of atmospheric ozone and temperature in 2-D radiative-photochemical model  

NASA Technical Reports Server (NTRS)

On the basis of the 2-D radiative-photochemical model of the ozone layer at heights 0 to 60 km in the Northern Hemisphere there are revealed and analyzed in detail the characteristic features of the season-altitude-latitude variations of ozone and temperature due to changes of the solar flux during the 11 year cycle, electron and proton precipitations.

Dyominov, I. G.

1989-01-01

121

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

122

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

123

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

124

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

125

Imaging of THz waves in 2D photonic crystal structures embedded in a slab waveguide  

E-print Network

We present space- and time-resolved simulations and measurements of single-cycle terahertz (THz) waves propagating through two-dimensional (2D) photonic crystal structures embedded in a slab waveguide. Specifically, we use ...

Peier, P.

126

Automatic deployment of a 2-D geophone array for efficient ultra-shallow seismic imaging  

E-print Network

the efficiency of 3-D shallow seismic 53acquisition can have transformative implications in fields 54of study where 2-D surveying is used today. Environmental, 55geotechnical, engineering, hydrogeologic, sedimentologic, 56tectonic, glaciologic, and archaeologic...

Tsoflias, Georgios P.; Steeples, Don W.; Czarnecki, Gerard P.; Sloan, Steven D.; Eslick, Robert C.

2006-01-01

127

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

NASA Astrophysics Data System (ADS)

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.

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

128

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

129

2-D Receiver Function Image of the Crust and Upper Mantle Beneath Western Turkey  

NASA Astrophysics Data System (ADS)

Turkey is located in a seismically active region. Seismicity mainly governed by the interaction of African, Arabian and Eurasian plates and in result of these motions Turkey has main fault zones and main tectonic active areas that comprise the subduction, continental collision or extensional regime. Western Turkey represents the extensional regime and subduction where the African plate subducting beneath Anatolian plate. Destructive earthquakes generally occur in the upper crust and determination of the discontinuities and velocity structure has an important role for understanding of seismicity models. In the study region, we do not have enough study that reflects the crustal structure of the region. We determined the velocity discontinuities beneath the broadband seismic stations which were located in western Turkey using receiver function (RF) analysis of the P-wave coda portions. For this purpose, we selected 33 stations and 50 teleseismic earthquakes that were occurred between 2007 and 2008. We computed the radial receiver functions using extended time multi taper method using Gaussian low-pass filter 0.3 Hz for each station and we selected two profiles: the one is running from the northwest of Bozcaada to Konya city and the other is running from the northeast of Izmir to the northeast corner of Rhodes island. We produced depth-migrated RFs using one dimensional velocity models that based on previous studies. We find that radial receiver function waveforms indicate strong lateral variations in the crust and uppermost mantle. Receiver function 2- D images indicate that Conrad discontinuity settled about 15 km beneath some stations and Moho discontinuity should be lie between 30 and 40 km for the first profile and between 20 and 30 km for the second profile. Crustal thickness increase from west to east related with the tectonic process that Arabian plate collides with the Anatolian plate at the eastern part of Turkey and it pushes the Anatolian plate to the west along the North Anatolian and East Anatolian Fault Zones. Difference between Moho depths along these two profiles indicates that the region is exposed to different tectonic forces that second profile is affected by subduction of African plate under Anatolian plate and active tectonic of Aegean Sea and it seems thinner than first profile.

Tezel, T.; Shibutani, T.

2008-12-01

130

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

131

Rigid 2D/3D slice-to-volume registration and its application on fluoroscopic CT images  

SciTech Connect

Registration of single slices from FluoroCT, CineMR, or interventional magnetic resonance imaging to three dimensional (3D) volumes is a special aspect of the two-dimensional (2D)/3D registration problem. Rather than digitally rendered radiographs (DRR), single 2D slice images obtained during interventional procedures are compared to oblique reformatted slices from a high resolution 3D scan. Due to the lack of perspective information and the different imaging geometry, convergence behavior differs significantly from 2D/3D registration applications comparing DRR images with conventional x-ray images. We have implemented a number of merit functions and local and global optimization algorithms for slice-to-volume registration of computed tomography (CT) and FluoroCT images. These methods were tested on phantom images derived from clinical scans for liver biopsies. Our results indicate that good registration accuracy in the range of 0.5 degree sign and 1.0 mm is achievable using simple cross correlation and repeated application of local optimization algorithms. Typically, a registration took approximately 1 min on a standard personal computer. Other merit functions such as pattern intensity or normalized mutual information did not perform as well as cross correlation in this initial evaluation. Furthermore, it appears as if the use of global optimization algorithms such as simulated annealing does not improve reliability or accuracy of the registration process. These findings were also confirmed in a preliminary registration study on five clinical scans. These experiments have, however, shown that a strict breath-hold protocol is inevitable when using rigid registration techniques for lesion localization in image-guided biopsy retrieval. Finally, further possible applications of slice-to-volume registration are discussed.

Birkfellner, Wolfgang; Figl, Michael; Kettenbach, Joachim; Hummel, Johann; Homolka, Peter; Schernthaner, Ruediger; Nau, Thomas; Bergmann, Helmar [Center for Biomedical Engineering and Physics, Medical University Vienna, Vienna A-1090 (Austria); Department of Computing, Imperial College, London (United Kingdom); Department of Radiology, Division of Interventional Radiology, Medical University Vienna, Vienna A-1090 (Austria); Center for Biomedical Engineering and Physics, Medical University Vienna, Vienna A-1090 (Austria); Department of Radiology, Division of Interventional Radiology, Medical University Vienna, Vienna A-1090 (Austria); St. George Clinical School, University of New South Wales (Australia); Center for Biomedical Engineering and Physics, Medical University Vienna (Austria)

2007-01-15

132

2D grating simulation for X-ray phase-contrast and dark-field imaging with a Talbot interferometer  

NASA Astrophysics Data System (ADS)

Talbot interferometry is a recently developed and an extremely powerful X-ray phase-contrast imaging technique. Besides giving access to ultra-high sensitivity differential phase contrast images, it also provides the dark field image, which is a map of the scattering power of the sample. In this paper we investigate the potentialities of an improved version of the interferometer, in which two dimensional gratings are used instead of standard line grids. This approach allows to overcome the difficulties that might be encountered in the images produced by a one dimensional interferometer. Among these limitations there are the phase wrapping and quantitative phase retrieval problems and the directionality of the differential phase and dark-field signals. The feasibility of the 2D Talbot interferometer has been studied with a numerical simulation on the performances of its optical components under different circumstances. The gratings can be obtained either by an ad hoc fabrication of the 2D structures or by a superposition of two perpendicular linear grids. Through this simulation it has been possible to find the best parameters for a practical implementation of the 2D Talbot interferometer.

Zanette, Irene; David, Christian; Rutishauser, Simon; Weitkamp, Timm

2010-04-01

133

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

134

Comparing 2D matched filter response and Gabor filter methods for vessel segmentation in retinal images  

Microsoft Academic Search

Analysis of retinal blood vessels is extremely important for diagnosis and treatment of many diseases such as diabetic retinopathy, hypertension, glukoma, arteriosclerosis etc. Therefore, especially vessel segmentation is one of the most critical steps for detection and treatment of these diseases. In this paper, Gabor filter and 2D matched filter response methods, which are used to enhance blood vessels, were

Zafer Yavuz; Cemal Köse

2010-01-01

135

Echocardiography examinations Conventional echocardiography and 2D color tissue Doppler imaging (TDI) were  

E-print Network

-time color Doppler was superimposed on the gray scale with a high frame rate (> 150 frames/sec). DopplerMethods Echocardiography examinations Conventional echocardiography and 2D color tissue Doppler examined with a Vivid 7 ultrasound unit equipped with 5-7.5 and 2- 5MHz phased-array transducers (GE

Boyer, Edmond

136

Ultrasonic synthetic aperture imaging used to measure 2D velocity fields in real time  

Microsoft Academic Search

Synthetic aperture techniques have been adopted to improve spatial resolution and provide an extremely fast 3D data acquisition modality for measuring the velocity of relatively fast moving structures such as the heart muscle or blood in arterial stenoses. Synthetic aperture techniques require the use of a 2D transducer array as well as very fast signal acquisition and processing capabilities. A

U. Moser; M. Anliker; P. Schumacher

1991-01-01

137

Segmentation of 3D CT Volume Images Using a Single 2D Atlas  

E-print Network

images is an important first step in the analysis of medical images. A lot of research has been performed for the segmentation of brain images. This paper presents a method that can segment multiple slices of an abdominal CT and challenging than brain image segmentation. Test results show that our method can handle large variations

Leow, Wee Kheng

138

Adaptive Spatial Binning of 2D Spectra and Images Using Voronoi Tessellations  

E-print Network

We present new techniques to perform adaptive spatial binning of two-dimensional (2D) data to reach a chosen constant signal-to-noise ratio per bin. These methods are required particularly for the proper analysis of Integral Field Spectrograph (IFS) observations, but can also be used for standard photometric imagery. Various schemes are tested and compared using data obtained with the panoramic IFS SAURON.

Michele Cappellari; Yannick Copin

2002-02-20

139

Study on the imaging ability of the 2D neutron detector based on MWPC  

E-print Network

A 2D neutron detector based on 3He convertor and MWPC with an active area of 200 mm \\times 200 mm has been successfully designed and fabricated. The detector has been tested with Am/Be neutron source and with collimated neutron beam with wavelength of {\\lambda} = 1.37 {\\AA}. A best spatial resolution of 1.18 mm (FWHM) and good linearity were obtained. This is in good agreement with the theoretical calculations.

LiChao, Tian; Bin, Tang; JianRong, Zhou; HuiRong, Qi; RongGuang, Liu; Jian, Zhang; GuiAn, Yang; Hong, Xu; DongFeng, Chen; ZhiJia, Sun

2013-01-01

140

Study on the imaging ability of the 2D neutron detector based on MWPC  

NASA Astrophysics Data System (ADS)

A 2D neutron detector based on 3He convertor and MWPC with an active area of 200 mm×200 mm has been successfully designed and fabricated. The detector has been tested with Am/Be neutron source and with collimated neutron beam with the wavelength of ?=1.37 Å. The best spatial resolution of 1.18 mm (FWHM) and good linearity were obtained. This is in good agreement with theoretical calculations.

Tian, LiChao; Chen, YuanBo; Tang, Bin; Zhou, JianRong; Qi, HuiRong; Liu, RongGuang; Zhang, Jian; Yang, GuiAn; Xu, Hong; Chen, DongFeng; Sun, ZhiJia

2013-10-01

141

Integration of Local Image Cues for Probabilistic 2D Pose , Dimitrios Makris1  

E-print Network

of antisocial behaviours from images captured from CCTV cameras. A robust system should be able to deal of 10 body parts which is consistent with the segmentation resolution expected from CCTV images. Our

Nebel, Jean-Christophe

142

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

143

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

144

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

145

Combined 3D photoacoustic and 2D fluorescence imaging of indocyanine green contrast agent flow  

NASA Astrophysics Data System (ADS)

Photoacoustic imaging uses laser induced ultrasound transients to generate optical absorption maps of the illuminated volume. In this work, we used a custom built photoacoustic imaging system consisting of a 60-channel transducer array, a 50 MHz data acquisition system, and an Nd:YAG pumped OPO laser, to perform simultaneous photoacoustic and fluorescence imaging. A single 780 nm laser pulse generated both ultrasound and fluorescence, enabling reconstruction of images for both modalities with near perfect temporal co-registration. The result highlighted the ability of photoacoustic imaging to supplement fluorescence data when optical scatter reduces fluorescence resolution beyond its useful range.

Kosik, Ivan; Carson, Jeffrey J. L.

2013-03-01

146

Multilevel image thresholding based on 2D histogram and maximum Tsallis entropy--a differential evolution approach.  

PubMed

Multilevel thresholding amounts to segmenting a gray-level image into several distinct regions. This paper presents a 2D histogram based multilevel thresholding approach to improve the separation between objects. Recent studies indicate that the results obtained with 2D histogram oriented approaches are superior to those obtained with 1D histogram based techniques in the context of bi-level thresholding. Here, a method to incorporate 2D histogram related information for generalized multilevel thresholding is proposed using the maximum Tsallis entropy. Differential evolution (DE), a simple yet efficient evolutionary algorithm of current interest, is employed to improve the computational efficiency of the proposed method. The performance of DE is investigated extensively through comparison with other well-known nature inspired global optimization techniques such as genetic algorithm, particle swarm optimization, artificial bee colony, and simulated annealing. In addition, the outcome of the proposed method is evaluated using a well known benchmark--the Berkley segmentation data set (BSDS300) with 300 distinct images. PMID:23955760

Sarkar, Soham; Das, Swagatam

2013-12-01

147

2-D Fused Image Reconstruction approach for Microwave Tomography: a theoretical assessment using FDTD Model  

PubMed Central

This paper describes an efficient two-dimensional fused image reconstruction approach for Microwave Tomography (MWT). Finite Difference Time Domain (FDTD) models were created for a viable MWT experimental system having the transceivers modelled using thin wire approximation with resistive voltage sources. Born Iterative and Distorted Born Iterative methods have been employed for image reconstruction with the extremity imaging being done using a differential imaging technique. The forward solver in the imaging algorithm employs the FDTD method of solving the time domain Maxwell’s equations with the regularisation parameter computed using a stochastic approach. The algorithm is tested with 10% noise inclusion and successful image reconstruction has been shown implying its robustness. PMID:24058889

Bindu, G.; Semenov, S.

2013-01-01

148

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

149

2D and 3D ISAR image reconstruction through filtered back projection  

NASA Astrophysics Data System (ADS)

This paper presents a 3D ltered inversion scheme for turntable inverse synthetic aperture radar (ISAR) data from a scalar wave equation model. The proposed inversion scheme targets at the use of ltered back projection (FBP) and convolution back projection (CBP) imaging algorithms. In the paper, we also provide a derivation of a general imaging lter for the near-elds FBP and CBP imaging algorithms.

Ray, Timothy; Cao, Yufeng; Qiao, Zhijun; Chen, Genshe

2012-06-01

150

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

151

Exospheric temperatures deduced from 7320- to 7330-A /O/+//2P/ - O/+//2D// twilight observations  

NASA Technical Reports Server (NTRS)

A technique developed to deduce exospheric temperatures from the 7320- to 7330-A emission measured by the visible airglow experiment on board the AE-E satellite is considered. An excess emission in the measured 7320- to 7330-A brightness is noticed as a result of the interaction between the spacecraft and the atmosphere. The observed brightnesses are corrected for this effect. The galactic background emission is also carefully subtracted. The deduced temperatures exhibit a positive correlation with solar activity. It varies from approximately 700 K in late 1976 to approximately 1700 K at the peak of this solar cycle. The presence of a nonthermal oxygen corona is considered inconclusive.

Yee, J. H.; Abreu, V. J.

1982-01-01

152

New Insights to the Sawtooth Oscillation (m/n=1/1 mode) in Hot Plasmas based on High Resolution 2-D Images of Te Fluctuations  

SciTech Connect

Two dimensional (2-D) images of electron temperature fluctuations with high temporal and spatial resolution have been employed to study the sawtooth oscillation (m/n=1/1 mode) in Toroidal EXperiment for Technology Oriented Research (TEXTOR) tokamak plasmas. 2-D imaging data revealed new physics which were not available in previous studies based on the 1-D electron temperature measurement and X-ray tomography. Review of the physics of the sawtooth oscillation is given by comparative studies with prominent theoretical models suggest that a new physics paradigm is needed to describe the reconnection physics of the sawtooth oscillation. The new insights are: A pressure driven instability (not a ballooning mode) leads to the X-point reconnection process. The reconnection process is identified as a random 3-D local reconnection process with a helical structure. The reconnection time scale is similar for different types of sawtooth oscillation ("kink" and tearing type) and is significantly faster than the resistive time scale. Heat flow from the core to the outside of the inversion radius during the reconnection process is highly collective rather than stochastic.

H.K. Park, N.C. Luhmann, Jr, A.J.H. Donné, C.W. Domier, T. Munsat, M.J. Van de Pol, and the TEXTOR Team

2007-11-26

153

Aluminium oxide film for 2D photonic structure: room temperature formation  

Microsoft Academic Search

We report about aluminium anodic oxide films (AOFs) as self-organising microstructures for photonic band gap (PBG) crystal application. Structural analysis show that aluminium anodic oxide has formed a structure of randomly oriented clusters each of them consisting of neatly ordered submicrometer cells. Measurements show that at room temperature pores of up to 460 nm wide can be formed, thus, opening

I. Mikulskas; S. Juodkazis; A. Jagminas; Š. Meškinis; J. G. Dumas; J. Vaitkus; R. Tomasiunas

2001-01-01

154

Interactive 2D am! 3D Object Definition in Jvied ical Images Based on  

E-print Network

of intelligence, be ira human interacting with the display of the linage or a computer program exhibiting, and most such methods require, definition of the objects to be displayed. Clin.ical usefulness depends such methods. Objectdefuution in images re{juires an intelligent understanding of the images. TI1e source

North Carolina at Chapel Hill, University of

155

IEEE TRANSACTIONS ON MEDICAL IMAGING, VOL. 22, NO. 11, NOVEMBER 2003 1395 Gradient-Based 2-D/3-D Rigid Registration of  

E-print Network

at different times. In image-guided surgery, it is required to match the preoperative images and plans sought after methods is anatomy image- based rigid registration between preoperative and intraopera- tiveIEEE TRANSACTIONS ON MEDICAL IMAGING, VOL. 22, NO. 11, NOVEMBER 2003 1395 Gradient-Based 2-D/3-D

Joskowicz, Leo

156

978-1-4244-9166-7/10/$26.00 2010 IEEE 291 Protein Spot Detection in 2D-GE Images using Morphological Operators  

E-print Network

[11] and digital color eye fundus images [12]. These methods allow the extraction of image components in a digital grayscale image containing a few hundred up to several thousands of dark protein spots on a bright978-1-4244-9166-7/10/$26.00 �2010 IEEE 291 Protein Spot Detection in 2D-GE Images using

Athens, University of

157

Improving object detection in 2D images using a 3D world model  

NASA Astrophysics Data System (ADS)

A mobile robot operating in a netcentric environment can utilize offboard resources on the network to improve its local perception. One such offboard resource is a world model built and maintained by other sensor systems. In this paper we present results from research into improving the performance of Deformable Parts Model object detection algorithms by using an offboard 3D world model. Experiments were run for detecting both people and cars in 2D photographs taken in an urban environment. After generating candidate object detections, a 3D world model built from airborne Light Detection and Ranging (LIDAR) and aerial photographs was used to filter out false alarm using several types of geometric reasoning. Comparison of the baseline detection performance to the performance after false alarm filtering showed a significant decrease in false alarms for a given probability of detection.

Viggh, Herbert E. M.; Cho, Peter L.; Armstrong-Crews, Nicholas; Nam, Myra; Shah, Danelle C.; Brown, Geoffrey E.

2014-05-01

158

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

PubMed Central

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

2013-01-01

159

3D information from 2D images recorded in the European Modular Cultivation System on the ISS  

NASA Astrophysics Data System (ADS)

The European Modular Cultivation System (EMCS) on the ISS allows long-term biological experiments, e.g. on plants. Video cameras provide near real-time 2D images from these experiments. A method to obtain 3D coordinates and stereoscopic images from these 2D images has been developed and is described in this paper. The procedure was developed to enhance the data output of the MULTIGEN-1 experiment in 2007. One of the main objectives of the experiment was to study growth movements of the Arabidopsis plants and the effect of gravity on these. 3D data were important during parts of the experiment and the paper presents the method developed to acquire 3D data, the accuracy of the data, limitations to the technique and ways to improve the accuracy. Sequences of 3D data obtained from the MULTIGEN-1 experiment are used to illustrate the potential of this newfound capability of the EMCS. In the experiment setup, a positional depth accuracy of about ±0.4 mm for relative object distances and an absolute depth accuracy of about ±1.4 mm for time dependent phenomena was reached. The ability to both view biological specimens in 3D as well as obtaining quantitative 3D data added greatly to the scientific output of the MULTIGEN-1 experiment. The uses of the technique to other researchers and their experiments are discussed.

Solheim, B. G. B.

2009-12-01

160

Video segmentation using 3D hints contained in 2D images  

NASA Astrophysics Data System (ADS)

Int his paper, we present a new method for video sequence segmentation which can be used in video indexation applications. Our approach uses the image content as indices of segmentation. As for most video sequences, the images contain 3D hints. In order to detect these indices efficiently, we develop a two step Hough transformation (HT). The first HT tries to find all lines contained in video image. The second one according to the theory of projective geometry, gives the possible focus of expansion (FOE) point. Once we have all possible FOE positions, simple comparison of these positions tells the difference of video sequences. This method is robust not only for the images taken from well structured objects in the scene as buildings, roads and other man made entities, but also for the scene containing the flower field or other aligned natural objects. The results of the approach are shown at final part of the paper.

Ardebilian Fard, Mohsen; Tu, Xiaowei; Chen, Liming; Faudemay, Pascal

1996-11-01

161

Statistical methods for 2D-3D registration of optical and LIDAR images  

E-print Network

Fusion of 3D laser radar (LIDAR) imagery and aerial optical imagery is an efficient method for constructing 3D virtual reality models. One difficult aspect of creating such models is registering the optical image with the ...

Mastin, Dana Andrew

2009-01-01

162

Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites  

E-print Network

While magnetic resonance imaging (MRI) derives its signal from protons in water, additional biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of these much weaker signals ...

Kok, Trina

2012-01-01

163

2D-3D Rigid-Body Registration of X-Ray Fluoroscopy and CT Images  

E-print Network

The registration of pre-operative volumetric datasets to intra- operative two-dimensional images provides an improved way of verifying patient position and medical instrument loca- tion. In applications from orthopedics ...

Zollei, Lilla

2001-08-01

164

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

165

2D image registration using focused mutual information for application in dentistry.  

PubMed

Spatial alignment of image data is a common task in computer vision and medical imaging. This should preferentially be done with minimal intervention of an operator. Similarity measures with origin in the information theory such as mutual information (MI) have proven to be robust registration criteria for this purpose. Intra-oral radiographs can be considered images of piecewise rigid objects. Teeth and jaws are rigid but can be displaced with respect to each other. Therefore MI criteria combined with affine deformations tend to fail, when teeth and jaws move with respect to each other between image acquisitions. In this paper, we consider a focused weighing of pixels in the reference image. The resulting criterion, focused mutual information (FMI) is an adequate tool for the registration of rigid parts of a scene. We also show that the use of FMI is more robust for the subtraction of lateral radiographs of teeth, than MI confined to a region of interest. Furthermore, the criterion allows the follow-up of small carious lesions when upper and lower jaw moved between the acquisition of test and reference image. PMID:19406393

Jacquet, W; Nyssen, E; Bottenberg, P; Truyen, B; de Groen, P

2009-06-01

166

An active microwave imaging system for reconstruction of 2-D electrical property distributions.  

PubMed

The goal of this work is to develop a microwave-based imaging system for hyperthermia treatment monitoring and assessment. Toward this end, a four transmit channel and four receive channel hardware device and concomitant image reconstruction algorithm have been realized. The hardware is designed to measure electric fields (i.e., amplitude and phase) at various locations in a phantom tank with and without the presence of various heterogeneities using standard heterodyning principles. Particular attention has been paid to designing a receiver with better than 115 dB of linear dynamic range which is necessary for imaging biological tissue which often has very high conductivity, especially for tissues with high water content. A calibration procedure has been developed to compensate for signal loss due to three-dimensional radiation in the measured data, since the reconstruction process is only two-dimensional at the present time. Results are shown which demonstrate the stability and accuracy of the measurement system, the extent to which the forward computational model agrees with the measured field distribution when the electrical properties are known, and image reconstructions of electrically unknown targets of varying diameter. In the latter case, images of both the reactive and resistive component of the electrical property distribution have been recoverable. Quantitative information on object location, size, and electrical properties results when the target is approximately one-half wavelength in size. Images of smaller objects lack the same level of quantitative information, but remain qualitatively correct. PMID:8582719

Meaney, P M; Paulsen, K D; Hartov, A; Crane, R K

1995-10-01

167

Study of the electrical conductivity at finite temperature in 2D Si- MOSFETs  

NASA Astrophysics Data System (ADS)

We investigate the low temperature density dependent conductivity of two dimensional electron systems in zero magnetic field for sample Si-15 MOSFETs. The first purpose of this paper is to establish that the knee of the conductivity ?0 (?0 is the T = 0.3 conductivity obtained by linear extrapolation of the curves of ? (T) for different values of electron density, ns) as a function of the carrier densities ns for T = 0.3 K, observed by Lai et al. and Limouny et al. in previous work for two different samples, is independent of temperature. The second aim is the determination of the critical density, nc, of the metal-insulator transition. Many methods are used in this investigation of nc which have been already used for other samples. The motivation behind this last study is the observation of many values of nc that have been obtained from different methods and that are slightly different. We will use in this study three methods with the intention to infer which one is more appropriate to obtain nc.

Limouny, L.; Kaaouachi, A. El; Idrissi, H. El; Zatni, A.; Tata, O.; Daoudi, E.; Errai, M.; Dlimi, S.

2014-01-01

168

Pre-stack depth migration for improved imaging under seafloor canyons: 2D case study of Browse Basin, Australia*  

NASA Astrophysics Data System (ADS)

In the Browse Basin, as in many areas of the world, complex seafloor topography can cause problems with seismic imaging. This is related to complex ray paths, and sharp lateral changes in velocity. This paper compares ways in which 2D Kirchhoff imaging can be improved below seafloor canyons, using both time and depth domain processing. In the time domain, to improve on standard pre-stack time migration (PSTM) we apply removable seafloor static time shifts in order to reduce the push down effect under seafloor canyons before migration. This allows for better event continuity in the seismic imaging. However this approach does not fully solve the problem, still giving sub-optimal imaging, leaving amplitude shadows and structural distortion. Only depth domain processing with a migration algorithm that honours the paths of the seismic energy as well as a detailed velocity model can provide improved imaging under these seafloor canyons, and give confidence in the structural components of the exploration targets in this area. We therefore performed depth velocity model building followed by pre-stack depth migration (PSDM), the result of which provided a step change improvement in the imaging, and provided new insights into the area.

Debenham, Helen 124Westlake, Shane

2014-06-01

169

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

170

Machine learning of hierarchical clustering to segment 2D and 3D images.  

PubMed

We aim to improve segmentation through the use of machine learning tools during region agglomeration. We propose an active learning approach for performing hierarchical agglomerative segmentation from superpixels. Our method combines multiple features at all scales of the agglomerative process, works for data with an arbitrary number of dimensions, and scales to very large datasets. We advocate the use of variation of information to measure segmentation accuracy, particularly in 3D electron microscopy (EM) images of neural tissue, and using this metric demonstrate an improvement over competing algorithms in EM and natural images. PMID:23977123

Nunez-Iglesias, Juan; Kennedy, Ryan; Parag, Toufiq; Shi, Jianbo; Chklovskii, Dmitri B

2013-01-01

171

Robust and Fast 2D/3D Image Registration using Regression Learning  

E-print Network

27599, USA d Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065 residues in the registration. The method's application to Image-guided Radiation Therapy (IGRT), called CLARET (Correction via Limited-Angle Residues in External Beam Therapy), requires only a few seconds

172

2D and 3D high-resolution imaging to reconstruct the microstructure of clay media  

E-print Network

compacted clay (illite) system, considered to be an analogy for the clay matrix constituting clay diffusion driven transport of cations. The present study focuses on compacted illite properties in hopes of compacted illite material and analyzing the resulting images in order to extract information on pore space

Paris-Sud XI, Université de

173

Real time estimation and tracking of human body Center of Mass using 2D video imaging  

Microsoft Academic Search

Estimating the position of the body Center of Mass (CoM) is a very important issue in human movement analysis in general, and in gait analysis as a more specified field. There are different methods to estimate this feature of gait. However, application of video imaging for analyzing human gait has increased tremendously due to its availability and non- interrupting nature.

Amirhossein Bakhtiari; Fariba Bahrami; Babak Nadjar Araabi

2011-01-01

174

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

175

Membrane-mirror-based display for viewing 2D and 3D images  

NASA Astrophysics Data System (ADS)

Stretchable Membrane Mirrors (SMMs) have been developed at the University of Strathclyde as a cheap, lightweight and variable focal length alternative to conventional fixed- curvature glass based optics. A SMM uses a thin sheet of aluminized polyester film which is stretched over a specially shaped frame, forming an airtight cavity behind the membrane. Removal of air from that cavity causes the resulting air pressure difference to force the membrane back into a concave shape. Controlling the pressure difference acting over the membrane now controls the curvature or f/No. of the mirror. Mirrors from 0.15-m to 1.2-m in diameter have been constructed at the University of Strathclyde. The use of lenses and mirrors to project real images in space is perhaps one of the simplest forms of 3D display. When using conventional optics however, there are severe financial restrictions on what size of image forming element may be used, hence the appeal of a SMM. The mirrors have been used both as image forming elements and directional screens in volumetric, stereoscopic and large format simulator displays. It was found that the use of these specular reflecting surfaces greatly enhances the perceived image quality of the resulting magnified display.

McKay, Stuart; Mason, Steven; Mair, Leslie S.; Waddell, Peter; Fraser, Simon M.

1999-05-01

176

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

177

CONTOUR-BASED HIDDEN MARKOV MODEL TO SEGMENT 2D ULTRASOUND IMAGES Xiaoning Qian1  

E-print Network

" and contain speckles as appearance inhomogeneity in the brightness and contrast; (2) Ultrasound images often of their appear- ance variations including speckle as well as signal dropout. We propose a novel automatic, 18]. Using large training sets covering appearance varia- tions, these algorithms are capable

Qian, Xiaoning

178

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

179

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

180

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

181

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

182

Fast 2D-3D marker-based registration of CT and X-ray fluoroscopy images for image-guided surgery  

NASA Astrophysics Data System (ADS)

We propose a fast 2D-3D marker-based registration technique to fuse anatomical structure of 3D CT scans onto 2D X-ray fluoroscopy image. Our method is composed of three stages. First, DRRs (Digitally Reconstructed Radiography) are generated by maximum intensity projection based on hardware texture-based volume rendering. This technique is over 200 times faster than software-based one. Second, confirmation markers are automatically segmented in DRRs and X-ray fluoroscopy images, respectively. Third, in/out-plane registration is proposed for real-time performance. In out-plane registration, we search for an optimal position of X-ray source in a 3D spherical coordinate system. Then we calculate optimal translation and rotation vectors by using principal axes method in in-plane registration. Our method has been successfully six different CT and X-ray fluoroscopy pairs generated from cardiac phantom datasets. For accuracy evaluation, we calculate root-mean-squared error (RMSE) between confirmation markers of DRRs and X-ray fluoroscopy images. Experimental results show that our DRRs generation method performs very fast and the hierarchical registration effectively finds the matching of DRRs and 2D images.

Hong, Helen; Kim, Kyehyun; Park, Sungjin

2006-03-01

183

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. PMID:21684062

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

2013-01-01

184

A new method to quantify male pelvic floor displacement from 2D transperineal ultrasound images  

PubMed Central

Objective To develop a method to quantify displacement of pelvic structures during contraction of the pelvic floor muscles from transperineal ultrasound images in men and investigate the reliability of the method between days. Methods Ten healthy male volunteers (aged 28 – 41 years) attended two separate data collection sessions. Ultrasound images were recorded during voluntary pelvic floor muscle contractions in cine-loop (video) format with the transducer aligned in the mid-sagittal plane on the perineum. Five anatomical points were defined to represent contraction from striated urethral sphincter (SUS), levator ani (LA) and bulbocavernosus (BC) muscles. Displacement of each point was calculated between the relaxed and contracted-state images. Intra-class correlation coefficient (ICC) values were calculated from displacement data to assess reliability of the method between days. Results Displacements of the five anatomical points closely matched predictions based on anatomical considerations of the male pelvic musculature. ICC values for displacement data calculated from 1, 2 and 3 repetitions ranged between 0.82–0.95 for ICC (2,1), 0.85–0.97 for ICC (2,2) and 0.86–0.97 for ICC (2,3), respectively. Conclusions The new method reliably calculates displacements of points previously validated for females (Ano-rectal junction and bladder base) in addition to new measures of muscle actions (SUS and BC) specific to men. Future use might include assessment of clinical populations to understand how these displacements relate to symptoms of incontinence. PMID:23332998

Stafford, Ryan E.; Ashton-Miller, James A.; Constantinou, Christos E.; Hodges, Paul W.

2014-01-01

185

Sequential functional analysis of left ventricle from 2D-echocardiography images.  

PubMed

The sequential changes in shape of left ventricle (LV), which are the result of cellular interactions and their levels of organizational complexity, in its long axis view during one cardiac cycle are obtained. The changes are presented in terms of shape descriptors by processing of images obtained from a normal subject and two patients with dilated left ventricular cardio-myopathy. These images are processed, frame by frame, by a semi-automatic algorithm developed by MATLAB. This is consisting of gray scale conversion, the LV contour extraction by application of median and SRAD filters, and morphological operations. By filling the identified region with pixels and number of pixels along its contour the area and perimeter are calculated, respectively. From these the changes in LV volume and shape index are calculated. Based on these the stroke volume (SV) and ejection fraction (EF) are calculated. The changes in LV area, perimeter, volume and shape index in cardiac patients are less than that of normal subject. The calculated SV and EF of normal subject are within the range as obtained by various imaging procedures. PMID:24956894

Chacko, Rani; Singh, Megha

2014-06-01

186

Distributed Computing Architecture for Image-Based Wavefront Sensing and 2 D FFTs  

NASA Technical Reports Server (NTRS)

Image-based wavefront sensing (WFS) provides significant advantages over interferometric-based wavefi-ont sensors such as optical design simplicity and stability. However, the image-based approach is computational intensive, and therefore, specialized high-performance computing architectures are required in applications utilizing the image-based approach. The development and testing of these high-performance computing architectures are essential to such missions as James Webb Space Telescope (JWST), Terrestial Planet Finder-Coronagraph (TPF-C and CorSpec), and Spherical Primary Optical Telescope (SPOT). The development of these specialized computing architectures require numerous two-dimensional Fourier Transforms, which necessitate an all-to-all communication when applied on a distributed computational architecture. Several solutions for distributed computing are presented with an emphasis on a 64 Node cluster of DSPs, multiple DSP FPGAs, and an application of low-diameter graph theory. Timing results and performance analysis will be presented. The solutions offered could be applied to other all-to-all communication and scientifically computationally complex problems.

Smith, Jeffrey S.; Dean, Bruce H.; Haghani, Shadan

2006-01-01

187

Characterization of broadband MHD fluctuations during type-II edge localized modes as measured in 2D with ECE-imaging at ASDEX Upgrade  

NASA Astrophysics Data System (ADS)

The characterization of a broadband fluctuation that is typical for the type-II ELM regime at ASDEX Upgrade has been improved using the 2D capabilities of ECE-imaging. During the transition from the type-I to type-II ELMy phase, it has been found that electron temperature fluctuations form a broadband peak in the 19-65 kHz range. In the type-II phase, this broadband fluctuation reaches a maximum relative amplitude of almost 20% just inside the top of the pedestal. Simultaneously, the electron temperature profile is completely flattened at this location. The 2D distribution of the amplitude of this broadband fluctuation is such that, when averaged over time, a minimum occurs around the mid-plane. From the measurements of the nearby magnetic pickup coils, a similar broadband fluctuation seems visible in the same frequency range. However, this is peaked at a slightly lower frequency and does not show a similar minimum. From the analysis of the fluctuations on small timescales, the poloidal and toroidal mode numbers are estimated to be m ˜ 100 and n ˜ 21. Furthermore, activity reminiscent of beat waves has been observed, which might partially account for the fluctuation's broadband nature and the seeming velocity variation of single fluctuation passages. Overall, similarities between the characteristics of this broadband fluctuation and various precursors to type-I ELMs suggest that this fluctuation can play an important role in regulating the ELM cycle.

Boom, J. E.; Wolfrum, E.; Classen, I. G. J.; de Vries, P. C.; Maraschek, M.; Suttrop, W.; Pérez von Thun, C. P.; Donné, A. J. H.; Tobias, B. J.; Domier, C. W.; Luhmann, N. C., Jr.; Park, H. K.; the ASDEX Upgrade Team

2012-11-01

188

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

189

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

190

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

191

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

192

A Gaseous Compton Camera using a 2D-sensitive gaseous photomultiplier for Nuclear Medical Imaging  

NASA Astrophysics Data System (ADS)

A new Compton Camera (CC) concept based on a High Pressure Scintillation Chamber coupled to a position-sensitive Gaseous PhotoMultiplier for Nuclear Medical Imaging applications is proposed. The main goal of this work is to describe the development of a ?25×12 cm3 cylindrical prototype, which will be suitable for scintimammography and for small-animal imaging applications. The possibility to scale it to an useful human size device is also in study. The idea is to develop a device capable to compete with the standard Anger Camera. Despite the large success of the Anger Camera, it still presents some limitations, such as: low position resolution and fair energy resolutions for 140 keV. The CC arises a different solution as it provides information about the incoming photon direction, avoiding the use of a collimator, which is responsible for a huge reduction (10-4) of the sensitivity. The main problem of the CC's is related with the Doppler Broadening which is responsible for the loss of angular resolution. In this work, calculations for the Doppler Broadening in Xe, Ar, Ne and their mixtures are presented. Simulations of the detector performance together with discussion about the gas choice are also included .

Azevedo, C. D. R.; Pereira, F. A.; Lopes, T.; Correia, P. M. M.; Silva, A. L. M.; Carramate, L. F. N. D.; Covita, D. S.; Veloso, J. F. C. A.

2013-12-01

193

Push-broom hyperspectral image calibration and enhancement by 2D deconvolution with a variant response function estimate.  

PubMed

In this paper, we propose a novel method for spectral and spatial calibration and resolution enhancement of hyperspectral images by a two-step procedure. The spectral and spatial variability of the hyperspectral imaging system response function is characterized by a global parametric model, which is derived from a pair of calibration images corresponding to an exactly defined calibration target and a set of gas-discharge lamps. A 2D Richardson-Lucy deconvolution-based algorithm is used to remove the distortions and enhance the resolution of subsequently acquired hyperspectral images. The results of the characterization and deconvolution process obtained by the proposed method are thoroughly evaluated by an independent set of exactly defined calibration and spectral targets, and compared to the existing state-of-the-art characterization method. The proposed method significantly improves the spectral and spatial coregistration and provides more than five-fold resolution enhancement in the spatial and two-fold resolution enhancement in the spectral domain. PMID:25401909

Jemec, Jurij; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

2014-11-01

194

2-D directional ultrasonic passive matrix of 512 elementary transducers for projection imaging of biological structures  

NASA Astrophysics Data System (ADS)

The following paper presents an idea of minimising the number of connections of individual piezoelectric transducers in a row-column multielement passive matrix system used for imaging of biological media structure by means of ultrasonic projection method. Elementary transducers of a passive matrix are connected to one common electrode in rows and to another common electrode in columns. There are two groups of switches in this type of matrix, one for a selected active column and the other for a selected active row. When the transducer situated at the point of intersection of the selected row and column is activated, the activating signal in the passive matrix can travel through inactive transducers to other column and row lines despite their switches being opened (crosstalk). This phenomenon is advantageous in the context of achieving a directional beam of ultrasonic wave and reducing matrix input impedance.

Opieli?ski, Krzysztof J.; Pruchnicki, Piotr; Gudra, Tadeusz

2012-05-01

195

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

2011-10-01

196

MIA-QSAR: a simple 2D image-based approach for quantitative structure activity relationship analysis  

NASA Astrophysics Data System (ADS)

An accessible and quite simple QSAR method, based on 2D image analysis, is reported. A case study is carried out in order to compare this model with a previously reported sophisticated methodology. A well known set of ( S)- N-[(1-ethyl-2-pyrrolidinyl)methyl]-6-methoxybenzamides, compounds with affinity to the dopamine D 2 receptor subtype, was divided in 40 calibration compounds and 18 test compounds and the descriptors were generated from pixels of 2D structures of each compound, which can be drawn with aid of any appropriate program. Bilinear (conventional) PLS was utilized as the regression method and leave-one-out cross-validation was performed using the NIPALS algorithm. The good predicted Q2 value obtained for the series of test compounds (0.58), together with the similar prediction quality obtained to other data sets (nAChR ligands, HIV protease inhibitors, COX-2 inhibitors and anxiolytic agents), suggests that the model is robust and seems to be as applicable as more complex methods.

Freitas, Matheus P.; Brown, Steven D.; Martins, José A.

2005-03-01

197

2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurementsa)  

NASA Astrophysics Data System (ADS)

Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (˜1 ?s) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ˜0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

Lin, L.; Ding, W. X.; Brower, D. L.

2014-11-01

198

Transverse Strains in Muscle Fascicles during Voluntary Contraction: A 2D Frequency Decomposition of B-Mode Ultrasound Images  

PubMed Central

When skeletal muscle fibres shorten, they must increase in their transverse dimensions in order to maintain a constant volume. In pennate muscle, this transverse expansion results in the fibres rotating to greater pennation angle, with a consequent reduction in their contractile velocity in a process known as gearing. Understanding the nature and extent of this transverse expansion is necessary to understand the mechanisms driving the changes in internal geometry of whole muscles during contraction. Current methodologies allow the fascicle lengths, orientations, and curvatures to be quantified, but not the transverse expansion. The purpose of this study was to develop and validate techniques for quantifying transverse strain in skeletal muscle fascicles during contraction from B-mode ultrasound images. Images were acquired from the medial and lateral gastrocnemii during cyclic contractions, enhanced using multiscale vessel enhancement filtering and the spatial frequencies resolved using 2D discrete Fourier transforms. The frequency information was resolved into the fascicle orientations that were validated against manually digitized values. The transverse fascicle strains were calculated from their wavelengths within the images. These methods showed that the transverse strain increases while the longitudinal fascicle length decreases; however, the extent of these strains was smaller than expected. PMID:25328509

Wakeling, James M.

2014-01-01

199

Selective coding with controlled quality decay for 2D and 3D images in a JPEG2000 framework  

NASA Astrophysics Data System (ADS)

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 or perceived objectionable in some use cases. A simple quality decay management is proposed here, which makes use of concentric ROI with different scaling factors. This allows the technique to be perfectly consistent with the JPEG2000 part 2 ROI definition and description. Another considered issue is the extension of the selective ROI coding to a 3D Volume of Interest coding. This extension is currently under consideration for the part 10 of JPEG2000, JP3D. An easy and effective 2D to 3D extension for the VOI definition and description is proposed here: a VOI is defined by a set composition of ROI generated solids, where ROI are defined along one or more volume cutting direction, and is described by the relative set of ROI parameters. Moreover, the quality decay management can be applied to this extension. The proposed techniques could have a significant impact on the selective coding of medical images and volumes. Image quality issues are very important but very critical factors in that field, which also constitutes the dominant market for 3D applications. Therefore, some experiments are presented on medical images and volumes in order evaluate the benefits of the proposed approaches in terms of diagnostic quality improvement with respect to a conventional ROI coding usage.

Signoroni, Alberto; Lazzaroni, Fabio; Leonardi, Riccardo

2003-06-01

200

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

201

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

202

2D imaging in a 3D world: Observing sub-grain scale variations and secondary mineral precipitates in reacted pore networks  

NASA Astrophysics Data System (ADS)

Advancements in 3D imaging techniques and analysis methods, and easier access to benchtop 3D X-ray microscopes, have led to a proliferation of 3D imaging studies of chemical alterations within porous media. However, 2D imaging methods continue to offer complementary insights into processes controlling sub-grain scale variations in mineralogy and intragranular porosity that are often difficult to observe with 3D methods. For example, 2D imaging studies of mineral precipitation-induced changes in the pore network structure including detailed observations of distributions of secondary mineral precipitates can be coupled with 3D image analysis of a pore network to determine the pore properties required to infer permeability. In this work, the combined advantages of 2D and 3D imaging methods are highlighted through 3D X-ray Computed Microtomography (X-ray CT) and 2D Scanning Electron Microscopy (SEM) imaging of a reacted column experiment in the context of the Hanford, WA site and a sedimentary rock sample from the Alberta basin. Both samples were imaged using 3D X-ray CT imaging at a voxel resolution of 4 ?m and analyzed using 3DMA Rock to determine pore and throat size distributions as well as pore coordination numbers. Polished sections were then created from each sample and imaged using 2D SEM imaging with resolutions of 0.4 ?m for the reacted column and an order of magnitude larger for the sedimentary rock. 2D images were analyzed using an erosion dilation method to determine pore and throat size distributions that were then corrected using sample-specific bias correction factors. The permeability of each sample was predicted from pore network models informed with the 2D or 3D pore and throat size distributions and the coordination numbers determined from the 3D analysis. Differences in 2D and 3D image resolutions resulted in over- or under- estimating small pore throats and led to predicted permeabilities that differed by orders of magnitude. For both samples, higher resolution images resulted in over-estimating small pore throats and under-estimating expected permeability. While higher resolution images are generally favored, they may not improve predictions of permeability as they require additional processing to distinguish small flow-conducting pore throats from surface roughness features. While 3D imaging is required to determine the network coordination, 2D imaging is necessary to understand where secondary minerals precipitate within the pore network and to quantify sub-grain scale variations. These advantages are demonstrated through SEM imaging of polished sections from the reacted column experiment. 2D images revealed that secondary mineral precipitates occurred as a relatively uniform coating on grain surfaces, unrelated to mineralogy, pore size, or other factors. SEM images also revealed new observations of sub-grain scale variations that showed that Hanford sand grains have a high amount of intragranular porosity and mineral precipitates formed in intragranular regions. These observations, which are important to understanding the reactive system, could not have been made if 3D imaging was used exclusively.

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

2012-12-01

203

A novel approach of computer-aided detection of focal ground-glass opacity in 2D lung CT images  

NASA Astrophysics Data System (ADS)

Focal Ground-Glass Opacity (fGGO) plays an important role in diagnose of lung cancers. This paper proposes a novel approach for detecting fGGOs in 2D lung CT images. The approach consists of two stages: extracting regions of interests (ROIs) and labeling each ROI as fGGO or non-fGGO. In the first stage, we use the techniques of Otsu thresholding and mathematical morphology to segment lung parenchyma from lung CT images and extract ROIs in lung parenchyma. In the second stage, a Bayesian classifier is constructed based on the Gaussian mixture Modeling (GMM) of the distribution of visual features of fGGOs to fulfill ROI identification. The parameters in the classifier are estimated from training data by the discriminative learning method of Max-Min posterior Pseudo-probabilities (MMP). A genetic algorithm is further developed to select compact and discriminative features for the classifier. We evaluated the proposed fGGO detection approach through 5-fold cross-validation experiments on a set of 69 lung CT scans that contain 70 fGGOs. The proposed approach achieves the detection sensitivity of 85.7% at the false positive rate of 2.5 per scan, which proves its effectiveness. We also demonstrate the usefulness of our genetic algorithm based feature selection method and MMP discriminative learning method through comparing them with without-selection strategy and Support Vector Machines (SVMs), respectively, in the experiments.

Li, Song; Liu, Xiabi; Yang, Ali; Pang, Kunpeng; Zhou, Chunwu; Zhao, Xinming; Zhao, Yanfeng

2013-02-01

204

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

205

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

206

Spin Dephasing as a Probe of Mode Temperature, Motional State Distributions, and Heating Rates in a 2D Ion Crystal  

E-print Network

We employ spin-dependent optical dipole forces to characterize the transverse center-of-mass (COM) motional mode of a two-dimensional Wigner crystal of hundreds of $^9$Be$^+$. By comparing the measured spin dephasing produced by the spin-dependent force with the predictions of a semiclassical dephasing model, we obtain absolute mode temperatures in excellent agreement with both the Doppler laser cooling limit and measurements obtained from a previously published technique (B. C. Sawyer et al. Phys. Rev. Lett. \\textbf{108}, 213003 (2012)). Furthermore, the structure of the dephasing histograms allows for discrimination between initial thermal and coherent states of motion. We also apply the techniques discussed here to measure, for the first time, the ambient heating rate of the COM mode of a 2D Coulomb crystal in a Penning trap. This measurement places an upper limit on the anomalous single-ion heating rate due to electric field noise from the trap electrode surfaces of $\\frac{d\\bar{n}}{dt}\\sim 5$ s$^{-1}$ fo...

Sawyer, Brian C; Bollinger, John J

2014-01-01

207

Pressure-induced cooperative spin transition in ironII 2D coordination polymers: room-temperature visible spectroscopic study.  

PubMed

For the 2D coordination polymers [Fe(3-Fpy)(2)M(II)(CN)(4)] (M(II) = Ni, Pd, Pt), the pressure-induced spin crossover behavior has been investigated at 298 K by monitoring the distinct optical properties associated with each spin state. Cooperative first-order spin transition characterized by a piezohysteresis loop ca. 0.1 GPa wide was observed for the three derivatives. Application of the mean field regular solution theory has enabled estimation of the cooperative parameter, ?(p), and the enthalpy, ?H(HL)(p), associated with the spin transition for each derivative. These values, found in the intervals 6.8-7.9 and 18.6-20.8 kJ mol(-1), respectively, are consistent with those previously reported for thermally induced spin transition at constant pressure for the title compounds (Chem.-Eur. J.2009, 15, 10960). Relevance of the elastic energy, ?(elast), as a corrective parameter accounting for the pressure dependence of the critical temperature of thermally induced spin transitions (Clausius-Clapeiron equation) is also demonstrated and discussed. PMID:21599006

Levchenko, G; Bukin, G V; Terekhov, S A; Gaspar, A B; Martínez, V; Muñoz, M C; Real, J A

2011-06-30

208

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

209

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

210

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

211

The evaluation of treatment plans in high-dose-rate endobronchial brachytherapy by utilizing 2D and 3D computed tomography imaging methods  

PubMed Central

Purpose To present comparison of treatment plans made by using 2D and 3D methods in the planning system, as well as to assess the quality of treatment plans using the 2D and 3D methods. Material and methods The studies involved a group of 31 patients with advanced lung cancer treated in the Brachytherapy Department of the Subcarpathian Cancer Center in Brzozów from 2011 to 2013. In total, 31 patients and 76 treatment plans were analyzed. We compared coverage of PTV planned in 3D and 2D. In the 3D method of treatment, three-dimensional images from computer tomography were used. In treatment plans performed using the 2D method, images from the simulator were used. Results The comparison of treatment plans made by using 2D and 3D methods is described. This comparison highlighted the significant differences between these two methods assessing reference dose coverage of the PTV by 100% and 85% isodose. Conclusions Reference doses with 100% coverage of the PTV in treatment applied with the 3D method are 31% higher than when applied with the 2D method. PMID:25337131

Kazalski, Damian; Lyczek, Jaroslaw; Kowalik, Lukasz

2014-01-01

212

Images of Gravitational and Magnetic Phenomena Derived from 2D Back-Projection Doppler Tomography of Interacting Binary Stars  

E-print Network

We have used 2D back-projection Doppler tomography as a tool to examine the influence of gravitational and magnetic phenomena in interacting binaries which undergo mass transfer from a magnetically-active star onto a non-magnetic main sequence star. This multi-tiered study of over 1300 time-resolved spectra of 13 Algol binaries involved calculations of the predicted dynamical behavior of the gravitational flow and the dynamics at the impact site, analysis of the velocity images constructed from tomography, and the influence on the tomograms of orbital inclination, systemic velocity, orbital coverage, and shadowing. The H$\\alpha$ tomograms revealed eight sources: chromospheric emission, a gas stream along the gravitational trajectory, a star-stream impact region, a bulge of absorption or emission around the mass-gaining star, a Keplerian accretion disk, an absorption zone associated with hotter gas, a disk-stream impact region, and a hot spot where the stream strikes the edge of a disk. We described several me...

Richards, Mercedes T; Fisher, John G; Conover, Marshall J

2014-01-01

213

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

214

Elastic image registration versus speckle tracking for 2-D myocardial motion estimation: a direct comparison in vivo.  

PubMed

Despite the availability of multiple solutions for assessing myocardial strain by ultrasound, little is currently known about the relative performance of the different methods. In this study, we sought to contrast two strain estimation techniques directly (speckle tracking and elastic registration) in an in vivo setting by comparing both to a gold standard reference measurement. In five open-chest sheep instrumented with ultrasonic microcrystals, 2-D images were acquired with a GE Vivid7 ultrasound system. Radial (?(RR)), longitudinal (?(LL)), and circumferential strain (?(CC)) were estimated during four inotropic stages: at rest, during esmolol and dobutamine infusion, and during acute ischemia. The correlation of the end-systolic strain values of a well-validated speckle tracking approach and an elastic registration method against sonomicrometry were comparable for ?(LL) ( r=0.70 versus r=0.61, respectively; p=0.32) and ?(CC) ( r=0.73 versus r=0.80 respectively; p=0.31). However, the elastic registration method performed considerably better for ?(RR) ( r=0.64 versus r=0.85 respectively; p=0.09). Moreover, the bias and limits of agreement with respect to the reference strain estimates were statistically significantly smaller in this direction . This could be related to regularization which is imposed during the motion estimation process as opposed to an a posteriori regularization step in the speckle tracking method. Whether one method outperforms the other in detecting dysfunctional regions remains the topic of future research. PMID:23204281

Heyde, Brecht; Jasaityte, Ruta; Barbosa, Daniel; Robesyn, Valérie; Bouchez, Stefaan; Wouters, Patrick; Maes, Frederik; Claus, Piet; D'hooge, Jan

2013-02-01

215

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. PMID:24672759

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

2014-01-01

216

Fast magnetic resonance temperature imaging for focused ultrasound thermal therapy  

NASA Astrophysics Data System (ADS)

The current standard for temperature sensitive imaging using magnetic resonance (MR) is 2-D, spoiled, fast gradient-echo (fGRE) phase-difference imaging exploiting temperature dependent changes in the proton resonance frequency (PRF). The echo-time (TE) for optimal sensitivity is larger than the typical repetition time (TR) of an fGRE sequence. Since TE must be less than TR in the fGRE sequence, this limits the technique's achievable sensitivity, spatial, and temporal resolution. This adversely affects both accuracy and volume coverage of the measurements. Accurate measurement of the rapid temperature changes associated with pulsed thermal therapies, such as high-intensity focused ultrasound (FUS), at optimal temperature sensitivity requires faster acquisition times than those currently available. Use of fast MR acquisition strategies, such as interleaved echo-planar and spiral imaging, can provide the necessary increase in temporal performance and sensitivity while maintaining adequate signal-to-noise and in-plane spatial resolution. This research explored the adaptation and optimization of several fast MR acquisition methods for thermal monitoring of pulsed FUS thermal therapy. Temperature sensitivity, phase- difference noise and phase-difference to phase- difference-to noise ratio for the different pulse sequences were evaluated under varying imaging parameters in an agar gel phantom to establish optimal sequence parameters for temperature monitoring. The temperature sensitivity coefficient of the gel phantom was measured, allowing quantitative temperature extrapolations. Optimized fast sequences were compared based on the ability to accurately monitor temperature changes at the focus of a high-intensity focused ultrasound unit, volume coverage, and contrast-to-noise ratio in the temperature maps. Operating parameters, which minimize complex phase- difference measurement errors introduced by use of the fast-imaging methods, were established.

Stafford, Roger Jason

217

Estimation of moving vehicle locations using wheel shape information in single 2-D lateral vehicle images by 3-D computer vision techniques  

Microsoft Academic Search

An approach to the estimation of moving lateral vehicle locations for driving assistance using wheel shape information in single 2-D vehicle images by 3-D computer vision techniques is proposed. The location scheme is supposed to be performed on a vehicle with a camera mounted on the front bumper. An analytical solution is applied to estimate locations of the lateral vehicle.

Chih-Chiun Lai; Wen-Hsiang Tsai

1999-01-01

218

Estimation of moving vehicle locations using wheel shape information in single 2-D lateral vehicle images by 3-D computer vision  

Microsoft Academic Search

An approach to the estimation of moving lateral vehicle locations for driving assistance using wheel shape information in single 2-D vehicle images by 3-D computer vision techniques is proposed. The location scheme is supposed to be performed on a vehicle with a camera mounted on the front bumper. An analytical solution is applied to estimate locations of the lateral vehicle.

Chih-Chiun Lai; Wen-Hsiang Tsai

1999-01-01

219

Location estimation and trajectory prediction of moving lateral vehicle using two wheel shapes information in 2-D lateral vehicle images by 3-D computer vision techniques  

Microsoft Academic Search

A novel approach to location estimation and trajectory prediction of moving lateral vehicle locations for driving assistance using wheels shape information in single 2-D vehicle images by 3-D computer vision techniques is proposed. The location scheme is supposed to be performed on a vehicle with a camera mounted on the front bumper. An analytical solution is applied to estimate the

Chih-chiun Lai; Wen-hsiang Tsai

2003-01-01

220

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

221

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

222

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

223

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

224

Quasi-phase-matched second-harmonic Talbot self-imaging in a 2D periodically-poled LiTaO3 crystal.  

PubMed

We demonstrate the improved second-harmonic Talbot self-imaging through the quasi-phase-matching technique in a 2D periodically-poled LiTaO(3) crystal. The domain structure not only composes a nonlinear optical grating which is necessary to realize nonlinear Talbot self-imaging, but also provides reciprocal vectors to satisfy the phase-matching condition for second-harmonic generation. Our experimental results show that quasi-phase-matching can improve the intensity of the second-harmonic Talbot self-imaging by a factor of 21. PMID:23787586

Liu, Dongmei; Wei, Dunzhao; Zhang, Yong; Zou, Jiong; Hu, X P; Zhu, S N; Xiao, Min

2013-06-17

225

0. A(N- 1995 IEEE-EMBC and CMBEC Theme 2 Imaging DMUSIC Algorithm for 2D NMR Signals  

E-print Network

Abstruct- In this paper, we will propose a superresolution scheme for the parameter estimation of two-be modeled as damped sinusoi ture determina will develop a super-resolution Zrequency and damping factor estimation algorithm-damped MUSIC (DMU-SIC) algorithm. Since the DMUSIC algorithm makes full use of the rank-deficiency and the Hankel property of the data matrix composed of the 2-D NMR data, compared with other NMR data analysis algorithms, it can resolve the NMR spectroscopy under low signal to noise ratio. The performance of the DMUSIC algorithm is demonstrated by simulations. Key words: 2D NMR Signal, DMUSIC algorithm I.

Ye Li; Javad Fhzavilar; K. J. Ray Liu

226

Significant acceleration of 2D-3D registration-based fusion of ultrasound and x-ray images by mesh-based DRR rendering  

NASA Astrophysics Data System (ADS)

For transcatheter-based minimally invasive procedures in structural heart disease ultrasound and X-ray are the two enabling imaging modalities. A live fusion of both real-time modalities can potentially improve the workflow and the catheter navigation by combining the excellent instrument imaging of X-ray with the high-quality soft tissue imaging of ultrasound. A recently published approach to fuse X-ray fluoroscopy with trans-esophageal echo (TEE) registers the ultrasound probe to X-ray images by a 2D-3D registration method which inherently provides a registration of ultrasound images to X-ray images. In this paper, we significantly accelerate the 2D-3D registration method in this context. The main novelty is to generate the projection images (DRR) of the 3D object not via volume ray-casting but instead via a fast rendering of triangular meshes. This is possible, because in the setting for TEE/X-ray fusion the 3D geometry of the ultrasound probe is known in advance and their main components can be described by triangular meshes. We show that the new approach can achieve a speedup factor up to 65 and does not affect the registration accuracy when used in conjunction with the gradient correlation similarity measure. The improvement is independent of the underlying registration optimizer. Based on the results, a TEE/X-ray fusion could be performed with a higher frame rate and a shorter time lag towards real-time registration performance. The approach could potentially accelerate other applications of 2D-3D registrations, e.g. the registration of implant models with X-ray images.

Kaiser, Markus; John, Matthias; Borsdorf, Anja; Mountney, Peter; Ionasec, Razvan; Nöttling, Alois; Kiefer, Philipp; Seeburger, Jörg; Neumuth, Thomas

2013-03-01

227

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

228

Watershed and Random Walks based Depth Estimation for Semi-Automatic 2D to 3D Image Conversion  

E-print Network

cameras and converting the existing 2D content into 3D [2]. The best solution is direct capture. However, direct capture requires special equipment and a complex post production pipeline. In some situation, like Schnyder extracts the depth information from sports content video by exploiting context-specific priors [4

Po, Lai-Man

229

A laminar cortical model for 3D perception of slanted and curved surfaces and of 2D images: development, attention, and bistability  

Microsoft Academic Search

A model of laminar visual cortical dynamics proposes how 3D boundary and surface representations arise from viewing slanted and curved 3D objects and 2D images. The 3D boundary representations emerge from non-classical receptive field interactions within intracortical and intercortical feedback circuits. Such non-classical interactions within cortical areas V1 and V2 contextually disambiguate classical receptive field responses to ambiguous visual cues

Stephen Grossberg; Gurumurthy Swaminathan

2004-01-01

230

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

231

Estimation of adequate setup margins and threshold for position errors requiring immediate attention in head and neck cancer radiotherapy based on 2D image guidance  

PubMed Central

Background We estimated sufficient setup margins for head-and-neck cancer (HNC) radiotherapy (RT) when 2D kV images are utilized for routine patient setup verification. As another goal we estimated a threshold for the displacements of the most important bony landmarks related to the target volumes requiring immediate attention. Methods We analyzed 1491 orthogonal x-ray images utilized in RT treatment guidance for 80 HNC patients. We estimated overall setup errors and errors for four subregions to account for patient rotation and deformation: the vertebrae C1-2, C5-7, the occiput bone and the mandible. Setup margins were estimated for two 2D image guidance protocols: i) imaging at first three fractions and weekly thereafter and ii) daily imaging. Two 2D image matching principles were investigated: i) to the vertebrae in the middle of planning target volume (PTV) (MID_PTV) and ii) minimizing maximal position error for the four subregions (MIN_MAX). The threshold for the position errors was calculated with two previously unpublished methods based on the van Herk’s formula and clinical data by retaining a margin of 5 mm sufficient for each subregion. Results Sufficient setup margins to compensate the displacements of the subregions were approximately two times larger than were needed to compensate setup errors for rigid target. Adequate margins varied from 2.7 mm to 9.6 mm depending on the subregions related to the target, applied image guidance protocol and early correction of clinically important systematic 3D displacements of the subregions exceeding 4 mm. The MIN_MAX match resulted in smaller margins but caused an overall shift of 2.5 mm for the target center. Margins???5mm were sufficient with the MID_PTV match only through application of daily 2D imaging and the threshold of 4 mm to correct systematic displacement of a subregion. Conclusions Adequate setup margins depend remarkably on the subregions related to the target volume. When the systematic 3D displacement of a subregion exceeds 4 mm, it is optimal to correct patient immobilization first. If this is not successful, adaptive replanning should be considered to retain sufficiently small margins. PMID:24020432

2013-01-01

232

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

233

Synchronized 2D/3D optical mapping for interactive exploration and real-time visualization of multi-function neurological images.  

PubMed

Efficient software with the ability to display multiple neurological image datasets simultaneously with full real-time interactivity is critical for brain disease diagnosis and image-guided planning. In this paper, we describe the creation and function of a new comprehensive software platform that integrates novel algorithms and functions for multiple medical image visualization, processing, and manipulation. We implement an opacity-adjustment algorithm to build 2D lookup tables for multiple slice image display and fusion, which achieves a better visual result than those of using VTK-based methods. We also develop a new real-time 2D and 3D data synchronization scheme for multi-function MR volume and slice image optical mapping and rendering simultaneously through using the same adjustment operation. All these methodologies are integrated into our software framework to provide users with an efficient tool for flexibly, intuitively, and rapidly exploring and analyzing the functional and anatomical MR neurological data. Finally, we validate our new techniques and software platform with visual analysis and task-specific user studies. PMID:23968722

Zhang, Qi; Alexander, Murray; Ryner, Lawrence

2013-01-01

234

Tuning the Growth Pattern in 2D Confinement Regime of Sm2O3 and the Emerging Room Temperature Unusual Superparamagnetism.  

PubMed

Programming the reaction chemistry for superseding the formation of Sm2O3 in a competitive process of formation and dissolution, the crystal growth patterns are varied and two different nanostructures of Sm2O3 in 2D confinement regime are designed. Among these, the regular and self-assembled square platelets nanostructures exhibit paramagnetic behavior analogous to the bulk Sm2O3. But, the other one, 2D flower like shaped nanostructure, formed by irregular crystal growth, shows superparamagnetism at room temperature which is unusual for bulk paramagnet. It has been noted that the variation in the crystal growth pattern is due to the difference in the binding ability of two organic ligands, oleylamine and oleic acid, used for the synthesis and the magnetic behavior of the nanostructures is related to the defects incorporated during the crystal growth. Herein, we inspect the formation chemistry and plausible origin of contrasting magnetism of these nanostructures of Sm2O3. PMID:25269458

Guria, Amit K; Dey, Koushik; Sarkar, Suresh; Patra, Biplab K; Giri, Saurav; Pradhan, Narayan

2014-01-01

235

Tuning the Growth Pattern in 2D Confinement Regime of Sm2O3 and the Emerging Room Temperature Unusual Superparamagnetism  

NASA Astrophysics Data System (ADS)

Programming the reaction chemistry for superseding the formation of Sm2O3 in a competitive process of formation and dissolution, the crystal growth patterns are varied and two different nanostructures of Sm2O3 in 2D confinement regime are designed. Among these, the regular and self-assembled square platelets nanostructures exhibit paramagnetic behavior analogous to the bulk Sm2O3. But, the other one, 2D flower like shaped nanostructure, formed by irregular crystal growth, shows superparamagnetism at room temperature which is unusual for bulk paramagnet. It has been noted that the variation in the crystal growth pattern is due to the difference in the binding ability of two organic ligands, oleylamine and oleic acid, used for the synthesis and the magnetic behavior of the nanostructures is related to the defects incorporated during the crystal growth. Herein, we inspect the formation chemistry and plausible origin of contrasting magnetism of these nanostructures of Sm2O3.

Guria, Amit K.; Dey, Koushik; Sarkar, Suresh; Patra, Biplab K.; Giri, Saurav; Pradhan, Narayan

2014-10-01

236

Tuning the Growth Pattern in 2D Confinement Regime of Sm2O3 and the Emerging Room Temperature Unusual Superparamagnetism  

PubMed Central

Programming the reaction chemistry for superseding the formation of Sm2O3 in a competitive process of formation and dissolution, the crystal growth patterns are varied and two different nanostructures of Sm2O3 in 2D confinement regime are designed. Among these, the regular and self-assembled square platelets nanostructures exhibit paramagnetic behavior analogous to the bulk Sm2O3. But, the other one, 2D flower like shaped nanostructure, formed by irregular crystal growth, shows superparamagnetism at room temperature which is unusual for bulk paramagnet. It has been noted that the variation in the crystal growth pattern is due to the difference in the binding ability of two organic ligands, oleylamine and oleic acid, used for the synthesis and the magnetic behavior of the nanostructures is related to the defects incorporated during the crystal growth. Herein, we inspect the formation chemistry and plausible origin of contrasting magnetism of these nanostructures of Sm2O3. PMID:25269458

Guria, Amit K.; Dey, Koushik; Sarkar, Suresh; Patra, Biplab K.; Giri, Saurav; Pradhan, Narayan

2014-01-01

237

Remote Temperature Estimation in Intravascular Photoacoustic Imaging  

PubMed Central

Intravascular photoacoustic (IVPA) imaging is based on the detection of laser-induced acoustic waves generated within the arterial tissue under pulsed laser irradiation. Generally, laser radiant energy levels are kept low (20 mJ/cm2) during photoacoustic imaging to conform to general standards for safe use of lasers on biological tissues. However, safety standards in intravascular photoacoustic imaging are not yet fully established. Consequently, monitoring spatio-temporal temperature changes associated with laser-tissue interaction is important to address thermal safety of IVPA imaging. In this study we utilize the IVUS based strain measurements to estimate the laser induced temperature increase. Temporal changes in temperature were estimated in a phantom modeling a vessel with an inclusion. A cross-correlation based time delay estimator was used to assess temperature induced strains produced by different laser radiant energies. The IVUS based remote measurements revealed temperature increases of 0.7±0.3°C, 2.9±0.2 °C and 5.0±0.2 °C, for the laser radiant energies of 30 mJ/cm2, 60 mJ/cm2 and 85 mJ/cm2 respectively. The technique was then used in imaging of ex vivo samples of a normal rabbit aorta. For arterial tissues, a temperature elevation of 1.1°C was observed for a laser fluence of 60 mJ/cm2 and lesser than 1°C for lower energy levels normally associated with IVPA imaging. Therefore, the developed ultrasound technique can be used to monitor temperature during IVPA imaging. Furthermore, the analysis based on the Arrhenius thermal damage model indicates no thermal injury in the arterial tissue; suggesting the safety of IVPA imaging PMID:17935861

Sethuraman, Shriram; Aglyamov, Salavat R.; Smalling, Richard W.; Emelianov, Stanislav Y.

2008-01-01

238

Absolute temperature stability of passive imaging radiometers  

NASA Astrophysics Data System (ADS)

A challenge in the development of multi-channel millimeter wave imaging radiometers is overcoming effects associated with the temperature dependence of receiver responsivity. In this paper, the stability of absolute radiation temperature measurements, made with direct and heterodyne detection radiometers, is investigated theoretically and experimentally. The agreement between theory and experiment is found to be good. Changes in measured radiation temperatures were found to be between 6 degree(s)K at 35 GHz and 145 degree(s)K at 220 GHz, for a one degree change in instrumental temperature. Suggestions are made, as to how the temperature stability of radiometers may be improved.

Salmon, Neil A.; Borrill, Jonathan R.; Gleed, David G.

1997-06-01

239

Selection and Testing of Pressure and Temperature Sensitive Dyes for 2-D Flow Characterization via Synthesized Microbeads  

NASA Astrophysics Data System (ADS)

Airborne temperature and pressure sensitive microbeads provide a vehicle with which to conduct two-dimensional flow characterization. An array of temperature and pressure sensitive dyes have been synthesized with microbeads (of silica, polystyrene, and polydimethylsiloxane) for this purpose. These microbeads were evaluated based on emission spectra, pressure response (0-760 torr), temperature response (5-45 C), and response time. Work will be presented showing the various combinations of dyes and microbead materials, as well as the testing process and examples of future application.

Perez, Alex; Zhu, Cun; Xia, Younan; Khalil, Gamal; Dabiri, Dana

2011-11-01

240

Simultaneous Microwave Imaging System for Density and Temperature Fluctuation Measurements on TEXTOR  

SciTech Connect

Diagnostic systems for fluctuation measurements in plasmas have, of necessity, evolved from simple 1-D systems to multi-dimensional systems due to the complexity of the MHD and turbulence physics of plasmas illustrated by advanced numerical simulations. Using the recent significant advancements in millimeter wave imaging technology, Microwave Imaging Reflectometry (MIR) and Electron Cyclotron Emission Imaging (ECEI), simultaneously measuring density and temperature fluctuations, are developed for TEXTOR. The MIR system was installed on TEXTOR and the first experiment was performed in September, 2003. Subsequent MIR campaigns have yielded poloidally resolved spectra and assessments of poloidal velocity. The new 2-D ECE Imaging system (with a total of 128 channels), installed on TEXTOR in December, 2003, successfully captured a true 2-D images of Te fluctuations of m=1 oscillation (''sawteeth'') near the q {approx} 1 surface for the first time.

H. Park; E. Mazzucato; T. Munsat; 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

2004-05-07

241

Development of code for 2-D distribution temperature transient analysis of asymmetric element linier using finite element method  

NASA Astrophysics Data System (ADS)

Transient of temperature distribution is found in many physical and engineering events that affect the state of the end of a process. Transient state in the form of geometry and complex boundary conditions is generally difficult to be solved analytically and can only be solved by a computer code. This study is aimed to develop a software code using the finite element method for the analysis of temperature transient distribution with the form of field element discretization asymmetric linier. The completion of the temperature distribution in the transient state is essential following the same procedure on the conditions of temperature distribution at steady state. The main difference is the load at which the load transient analysis is a function of time. Resolution process using finite element method (FEM) involves three stages, namely: the provision of data (preprocessor), problem solving (processor/ solver), interpretation of the results in the form of graphs and contour (postprocessor). Stages of the software development process start from the preprocessor program as making patterns/geometric shapes to be analyzed, discretized field with shape of element asymmetric, writing the number of nodes and elements, loads, initial conditions and boundary conditions. The process of the program code includes completing the matrix stiffness coefficient (K), and matrix load (a) time-based, or called the discretization time. The completion of time discretization uses the Galerkin Method. The stiffness of coefficient consists of stiffness geometry, capacitance matrices, or matrix moisture and the burden imposed as transient loads, such as heat flux load boundary, centralized heat load of boundary, and the initial temperature. In this way the expected completion of temperature transient distribution can be done more easily, quickly, and inexpensively. The code is written using Visual Basic.

Saragi, Elfrida

2014-09-01

242

Effects of Precipitation on Ocean Mixed-Layer Temperature and Salinity as Simulated in a 2-D Coupled Ocean-Cloud Resolving Atmosphere Model  

NASA Technical Reports Server (NTRS)

A two-dimensional coupled ocean-cloud resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets. The model couples a cloud resolving model with an embedded mixed layer-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-layer temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-layer temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-layer salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed layers and weak cooling rates so that the nocturnal mixed-layer temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed layers over convective areas while the nocturnal heat loss causes deep mixed layer over convection-free areas so that the mixed-layer temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures.

Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.

1999-01-01

243

Temperature Effects on Silicon-on-Insulator (SOI) Racetrack Resonators: A Coupled Analytic and 2-D Finite Difference Approach  

Microsoft Academic Search

This paper presents a detailed analysis of racetrack resonators on silicon on insulator substrates. Both the temperature effects and the particularities of silicon nanophotonics are considered throughout the approach. This paper provides a detailed description of the numerical modeling and its application to different designs, while providing several charts and fitting equations. The results presented in this paper can be

Nicolas Rouger; Lukas Chrostowski; Raha Vafaei

2010-01-01

244

High-performance GPU-based rendering for real-time, rigid 2D/3D-image registration and motion prediction in radiation oncology.  

PubMed

A common problem in image-guided radiation therapy (IGRT) of lung cancer as well as other malignant diseases is the compensation of periodic and aperiodic motion during dose delivery. Modern systems for image-guided radiation oncology allow for the acquisition of cone-beam computed tomography data in the treatment room as well as the acquisition of planar radiographs during the treatment. A mid-term research goal is the compensation of tumor target volume motion by 2D/3D Registration. In 2D/3D registration, spatial information on organ location is derived by an iterative comparison of perspective volume renderings, so-called digitally rendered radiographs (DRR) from computed tomography volume data, and planar reference x-rays. Currently, this rendering process is very time consuming, and real-time registration, which should at least provide data on organ position in less than a second, has not come into existence. We present two GPU-based rendering algorithms which generate a DRR of 512×512 pixels size from a CT dataset of 53 MB size at a pace of almost 100 Hz. This rendering rate is feasible by applying a number of algorithmic simplifications which range from alternative volume-driven rendering approaches - namely so-called wobbled splatting - to sub-sampling of the DRR-image by means of specialized raycasting techniques. Furthermore, general purpose graphics processing unit (GPGPU) programming paradigms were consequently utilized. Rendering quality and performance as well as the influence on the quality and performance of the overall registration process were measured and analyzed in detail. The results show that both methods are competitive and pave the way for fast motion compensation by rigid and possibly even non-rigid 2D/3D registration and, beyond that, adaptive filtering of motion models in IGRT. PMID:21782399

Spoerk, Jakob; Gendrin, Christelle; Weber, Christoph; Figl, Michael; Pawiro, Supriyanto Ardjo; Furtado, Hugo; Fabri, Daniella; Bloch, Christoph; Bergmann, Helmar; Gröller, Eduard; Birkfellner, Wolfgang

2012-02-01

245

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

246

Fast Intensity-based 2D-3D Image Registration of Clinical Data Using Light Daniel B. Russakoff  

E-print Network

neurosurgery [9], neurointerven- tions [6, 7], spinal surgery [8, 21], orthopedic surgery [5], and aortic- mation Ã? (rotation and translation) that aligns the coordi- nate system of the CT (3D) image

Pratt, Vaughan

247

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

248

Model-based measurement of food portion size for image-based dietary assessment using 3D/2D registration  

NASA Astrophysics Data System (ADS)

Dietary assessment is important in health maintenance and intervention in many chronic conditions, such as obesity, diabetes and cardiovascular disease. However, there is currently a lack of convenient methods for measuring the volume of food (portion size) in real-life settings. We present a computational method to estimate food volume from a single photographic image of food contained on a typical dining plate. First, we calculate the food location with respect to a 3D camera coordinate system using the plate as a scale reference. Then, the food is segmented automatically from the background in the image. Adaptive thresholding and snake modeling are implemented based on several image features, such as color contrast, regional color homogeneity and curve bending degree. Next, a 3D model representing the general shape of the food (e.g., a cylinder, a sphere, etc) is selected from a pre-constructed shape model library. The position, orientation and scale of the selected shape model are determined by registering the projected 3D model and the food contour in the image, where the properties of the reference are used as constraints. Experimental results using various realistically shaped foods with known volumes demonstrated satisfactory performance of our image-based food volume measurement method even if the 3D geometric surface of the food is not completely represented in the input image.

Chen, Hsin-Chen; Jia, Wenyan; Yue, Yaofeng; Li, Zhaoxin; Sun, Yung-Nien; Fernstrom, John D.; Sun, Mingui

2013-10-01

249

HSCT Assessment Calculations with the AER 2-D Model: Sensitivities to Transport Formulation, PSC Formulation, Interannual Temperature Variation. Appendix C  

NASA Technical Reports Server (NTRS)

The summary are: (1) Some chemical differences in background atmosphere are surprisingly large (NOY). (2) Differences in model transport explain a majority of the intertnodel differences in the absence of PSCs. (3) With PSCS, large differences exist in predicted O3 depletion between models with the same transport. (4) AER/LLNL model calculates more O3 depletion in NH than LLNL. (5) AER/GSFC model cannot match calculated O3 depletion of GSFC model in SH. and (6) Results sensitive to interannual temperature variations (at least in NH).

Weisenstein, Debra K.; Ko, Malcolm K. W.; Scott, Courtney J.; Shia, Run-Lie; Jackman, Charles; Fleming, Eric; Considine, David; Kinnison, Douglas; Connell, Peter; Rotman, Douglas

1998-01-01

250

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

251

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

252

A novel method to acquire 3D data from serial 2D images of a dental cast  

NASA Astrophysics Data System (ADS)

This paper introduced a newly developed method to acquire three-dimensional data from serial two-dimensional images of a dental cast. The system consists of a computer and a set of data acquiring device. The data acquiring device is used to take serial pictures of the a dental cast; an artificial neural network works to translate two-dimensional pictures to three-dimensional data; then three-dimensional image can reconstruct by the computer. The three-dimensional data acquiring of dental casts is the foundation of computer-aided diagnosis and treatment planning in orthodontics.

Yi, Yaxing; Li, Zhongke; Chen, Qi; Shao, Jun; Li, Xinshe; Liu, Zhiqin

2007-05-01

253

Simultaneous image segmentation and medial structure estimation: application to 2D and 3D vessel tree extraction  

NASA Astrophysics Data System (ADS)

We propose a variational approach which combines automatic segmentation and medial structure extraction in a single computationally efficient algorithm. In this paper, we apply our approach to the analysis of vessels in 2D X-ray angiography and 3D X-ray rotational angiography of the brain. Other variational methods proposed in the literature encode the medial structure of vessel trees as a skeleton with associated vessel radii. In contrast, our method provides a dense smooth level set map which sign provides the segmentation. The ridges of this map define the segmented regions skeleton. The differential structure of the smooth map (in particular the Hessian) allows the discrimination between tubular and other structures. In 3D, both circular and non-circular tubular cross-sections and tubular branching can be handled conveniently. This algorithm allows accurate segmentation of complex vessel structures. It also provides key tools for extracting anatomically labeled vessel tree graphs and for dealing with challenging issues like kissing vessel discrimination and separation of entangled 3D vessel trees.

Makram-Ebeid, Sherif; Stawiaski, Jean; Pizaine, Guillaume

2011-03-01

254

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

255

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

256

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 Differential Optical Absorption Spectroscopy (DOAS) method. The Heidelberg Airborne Imaging DOAS 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 give a technical description of the instrument including its custom-built 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 BRomine, Ozone, and Mercury EXperiment (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.

2014-10-01

257

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

258

A novel technique for single-shot energy-resolved 2D X-ray imaging of plasmas relevant for the Inertial Confinement Fusion  

E-print Network

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 - EPiC) 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 ICF related experiments will be reported in order to detail the new diagnostic.

Labate, L; Levato, T; Gizzi, L A

2012-01-01

259

A novel technique for single-shot energy-resolved 2D X-ray imaging of plasmas relevant for the Inertial Confinement Fusion  

E-print Network

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 - EPiC) 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 ICF related experiments will be reported in order to detail the new diagnostic.

L. Labate; P. Koester; T. Levato; L. A. Gizzi

2012-11-02

260

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

261

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

262

A frequency-based approach to locate common structure for 2D-3D intensity-based registration of setup images in prostate radiotherapy  

PubMed Central

In many radiotherapy clinics, geometric uncertainties in the delivery of 3D conformal radiation therapy and intensity modulated radiation therapy of the prostate are reduced by aligning the patient's bony anatomy in the planning 3D CT to corresponding bony anatomy in 2D portal images acquired before every treatment fraction. In this paper, we seek to determine if there is a frequency band within the portal images and the digitally reconstructed radiographs (DRRs) of the planning CT in which bony anatomy predominates over non-bony anatomy such that portal images and DRRs can be suitably filtered to achieve high registration accuracy in an automated 2D-3D single portal intensity-based registration framework. Two similarity measures, mutual information and the Pearson correlation coefficient were tested on carefully collected gold-standard data consisting of a kilovoltage cone-beam CT (CBCT) and megavoltage portal images in the anterior-posterior (AP) view of an anthropomorphic phantom acquired under clinical conditions at known poses, and on patient data. It was found that filtering the portal images and DRRs during the registration considerably improved registration performance. Without filtering, the registration did not always converge while with filtering it always converged to an accurate solution. For the pose-determination experiments conducted on the anthropomorphic phantom with the correlation coefficient, the mean (and standard deviation) of the absolute errors in recovering each of the six transformation parameters were ?x:0.18(0.19)°, ?y:0.04(0.04)°, ?z:0.04(0.02)°, tx:0.14(0.15) mm, ty:0.09(0.05) mm, and tz: 0.49(0.40) mm. The mutual information-based registration with filtered images also resulted in similarly small errors. For the patient data, visual inspection of the superimposed registered images showed that they were correctly aligned in all instances. The results presented in this paper suggest that robust and accurate registration can be achieved with intensity-based methods by focusing on rigid bony structures in the images while diminishing the influence of artifacts with similar frequencies as soft tissue. PMID:17822009

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

2009-01-01

263

Applicability of 2-D Time-Lapse High-Resolution Seismic Reflection Approach to Image Natural Salt-Dissolution and Subsidence in Central Kansas and Improved Post-Processed Vibroseis Data Characteristics  

E-print Network

The effectiveness of 2-D time-lapse imaging for monitoring natural dissolution of the Hutchinson Salt in eastern Reno County, Kansas was shown to be restricted when comparing high-resolution seismic reflection data acquired in 2008 with data...

Rice, Daniel

2009-01-12

264

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. PMID:23622681

2013-01-01

265

In vivo and in vitro characterization of R(+)-FIDA2, a novel dopamine D2/D3 receptor imaging agent  

SciTech Connect

FIDA2, (R)-(+)-2,3-dimethoxy-5-iodo-N-[1-(4`-fluorobenzyl)-2-pyrrolidinyl)-methyl]benzamide, is a new dopamine D2/D3 receptor imaging agent that can be labeled with either I-123 or F-18 for SPECT or PET imaging. In vitro binding studies of I-125 FIDA2 using dopamine D2 or D3 receptors expressed in Sf9 cells showed Kd values of 0.04 and 0.05 nM, respectively. In rat striatal homogenates, which contain a high density of dopamine D2 receptors, the ligand displayed a Kd of 0.04-0.06 nM. A series of in vivo SPECT images (transaxial sections, 2 mm) showed the radioactivity was localized in the area of the basal ganglia and reached peak concentrations in 11.2 {plus_minus} 5.9 min. The activity cleared at a rate of 33.5 {plus_minus} 9.4 %/hr. The target to nontarget ratios (basal ganglia to cerebellum) at time of peak, 1 hr, 2 hr and 3 hr p.i., were 1.1 {plus_minus} 0.4 (n=21), 3.5 {plus_minus} 1.0 (n=20), 6.3 {plus_minus} 2.9 (n=9, and 8.14 {plus_minus} 4.7 (n=9), respectively. At 90 min an injection of haloperidol or raclopride, dopamine D2/D3 receptor antagonists, displaced target activity but an injection of SCH23390, a dopamine D1 receptor antagonist, had little effect on activity in the basal ganglia. In addition, an injection of R-(+)-7-OH-PIPAT, a new ligand that is selective for the dopamine D3 receptor and the high affinity state of the dopamine D2 receptor, showed partial displacement ({approximately}15%) of I-123 FIDA2 binding in the basal ganglia. These studies indicate that FIDA2 may be a useful ligand for in vivo imaging of dopamine D2/D3 receptors.

Vessotskie, J.; Kung, M.P.; Ramaniello, G. [Univ. of Pennsylvania, Philadelphia, PA (United States)] [and others

1994-05-01

266

Impact of stratospheric aircraft on calculations of nitric acid trihydrate cloud surface area densities using NMC temperatures and 2D model constituent distributions  

NASA Technical Reports Server (NTRS)

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 and pressure. National Meteorological Center temperature fields are then used to determine monthly temperature frequency distributions, also as a function of latitude and pressure. The fractions of these distributions which fall below the critical temperatures for NAT formation are then used to determine the NAT cloud surface area density for each location in the model grid. By specifying heterogeneous reaction rates as functions of the surface area density, it is then possible to assess the effects of the NAT clouds on model constituent distributions. We also consider the increase in the NAT cloud formation in the presence of a fleet of stratospheric aircraft. The stratospheric aircraft NO(x) and H2O perturbations result in increased HNO3 as well as H2O. This increases the probability of NAT formation substantially, especially if it is assumed that the aircraft perturbations are confined to a corridor region.

Considine, David B.; Douglass, Anne R.

1994-01-01

267

Refraction statics and seismic imaging: 2-D versus 3-D solutions in the Western Desert of Egypt  

SciTech Connect

Careful review of old geophysical and geological data from the Western Desert of Egypt led to the decision of shooting a 3-D seismic survey targeted to solve some of the encountered geophysical problems such as difficulty of tracing the very thin pay zone, identifying the stratigraphic plays and the main two problems of the seismic method in the Western Desert which are statics and poor imaging. In a case history form illustrated by examples, the result of the 3-D solutions will be shown. Furthermore, an analytical approach will be undertaken to clarify and highlight the sources of those geophysical problems and how the 3-D solution helped in resolving them.

El-Emam, A. [General Petroleum Co., Cairo (Egypt); Nessim, M. [Western Geophysical Co., Cairo (Egypt)

1994-12-31

268

Infrared absorption imaging of 2D supersonic jet expansions: Free expansion, cluster formation, and shock wave patterns.  

PubMed

N2O/He gas mixtures are expanded through a 10?×?0.5 mm(2) slit nozzle and imaged by direct absorption vibrational spectroscopy, employing a HgCdTe focal plane array detector after interferometric modulation. N2O cluster formation in the free supersonic expansion is visualized. The expansion structure behind the frontal shock is investigated as a function of background pressure. At high pressures, a sequence of stationary density peaks along a narrow directed flow channel is characterized. The potential of the technique for the elucidation of aggregation mechanisms is emphasized. PMID:23862934

Zischang, Julia; Suhm, Martin A

2013-07-14

269

Low temperature magneto-photoluminescence investigations of the 2D hole system in p-type GaAs-AlGaAs heterojunctions  

NASA Astrophysics Data System (ADS)

Bandgap magneto-photoluminescence (PL) has been used to investigate the optical signature of high quality p-type GaAs-Al xGa 1- xAs single heterojunction samples in the quantum Hall effect (QHE) regime. The PL spectra show a series of sharp lines, with a number of bulk features attributed to free exciton emission and acceptor-related bound excitons evident. Significantly, however, one line within the complex PL spectrum, at slightly lower energy to the free exciton, becomes a dominant feature at low temperatures and has an intensity maximum which exhibits superlinear behaviour with excitation power that correlates with the v = 1 QHE. This line is assigned to an excitonic process at the heterointerface reminiscent of 2D excited subband recombination in n-type structures.

Davies, A. G.; Mitchell, E. E.; Clark, R. G.; Simmonds, P. E.; Silver, T. M.; Ritchie, D. A.; Frost, J. E. F.; Pepper, M.; Jones, G. A. C.

1994-07-01

270

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

271

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

272

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

273

STP Ising 2D Program  

NSDL National Science Digital Library

The STP Ising2D program is a Monte Carlo simulation of a two-dimensional Ising model in equilibrium with a heat bath at temperature T using the Metropolis or Wolff algorithms. The default is a lattice of linear dimension L=32 (for a total of N=L^2 spins) with no external field and heat bath temperature T=0. STP Ising2D is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_Ising2D.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-05-28

274

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

275

Inverted metamorphism and feedback between temperature and non-Newtonian viscosity in compressive shear zones: A 2D thermo-kinematic study.  

NASA Astrophysics Data System (ADS)

The thermal evolution within major compressive shear zones is still difficult to characterise due to the fact that various parameters and complex processes are involved. Among them, the heat production obtained by converting mechanical energy, commonly called "shear heating", appears to be one of the most important. Indeed, it controls the potential inversion location of isotherms at crustal-scale. This intense thermal perturbation, preserved in time, is often regarded as responsible for the establishment of a plurikilometric sequence of inverted metamorphism. Shear heating is proportionnal to the stress and strain intensities and, consequently, is strongly dependent on the strength of the shear zones. On one hand, this strength is controlled by the brittle rheology. On the other hand, it is controlled by the ductile rheology involving a non-Newtonian viscosity field depending on local lithology, strain rate and temperature. In the same time, this temperature is obviously controlled by the evolution of the local thermal budget and thus, by the cumulative shear heating and the dissipated thermal energy. Consequently, in order to understand the thermal evolution of a crustal compressive shear zone, we need to understand the respective influence of each one of these parameters involved in the local rheological behaviour. In order to adress this problem, we realised a parametric study based on a 2D-thermo- kinematical model. The velocity field (including isostasy compensation) is imposed in the whole model in order to simulate a thrust at crustal-scale. By this way, we are able to control the thrust thickness and the strain rate profile across the sheared area. At each time step, we determine the brittle/ductile transition, we compute the potential heat production (shear heating) and we solve the heat diffusion equation on the grid. The temperatures are then advected by markers following the velocity field. This model is voluntary simplified in order to control each parameter which allows us to test their influence on the geothermal inversion Our results show that the balance between heat production and heat diffusion is strongly influenced by the viscosity of the shear zone. A strain power law leads to the localisation of the thermal inversion around the strength peak. At the opposite, a Newtonian viscosity makes it to occur in the deepest crustal levels. The creep parameters specific to each lithology play a major role in the thermal development and on the inversion duration. Under realistic kinematic conditions, a significant thermal inversion is generated and continues over time for granitic rocks whereas a negligeable perturbation without inversion occurs when this initial rock is highly deformed and metasomatised.

Duprat-Oualid, Sylvia; Yamato, Philippe

2013-04-01

276

Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2-D time-lapse surface electrical resistivity tomography  

NASA Astrophysics Data System (ADS)

The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper, we use 2-D surface-based time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river water during high stage conditions. We inverted approximately 1200 data sets (400 per line over three lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. To invert the data, we use an image differencing approach that does not require regularization in the time dimension, enabling the inversion to accommodate the sharp, time varying contrasts in conductivity imposed by the moving water table. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location of river water intrusion beneath each line. The results reveal nonuniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity "break through" curves and longer river water residence times.

Wallin, E. L.; Johnson, T. C.; Greenwood, W. J.; Zachara, J. M.

2013-03-01

277

All c2d Spitzer Outflows  

NASA Astrophysics Data System (ADS)

Protostellar outflows can be well identified as diffuse knots in Spitzer IRAC images. We therefore propose to systematically search and characterize all outflows covered by the most extensive Spitzer imaging survey of local star formation, the Cores to Disks (c2d) Spitzer Legacy Program. This would create an extensive, homogenously studied (publicly available) legacy-style outflow sample without biases, likely the most comprehensive one available to date. It would replace existing studies that usually employ different methods for different regions, and do never probe a volume of the scale covered by c2d (5 large cloud complexes and about 90 isolated dense molecular cores). Our homogenous approach would, e.g., also allow to see known outflows in a new light, since existing analysis (e.g., on the geometry) is hard to compare between different samples. Furthermore, also young stellar objects can be well identified and characterized using Spitzer IRAC and MIPS images. This allows to probe the sources driving outflows, again in a more homogenous fashion than possible for previous studies. Based on existing complementary c2d data, which covers the 1 to 1000 micron wavelength range, we would derive protostellar properties (like bolometric luminosity and temperature) and associate these with the outflow properties. Thus, Spitzer?s unparalleled sensitivity to both outflows and stars offers the unique chance to systematically relate the properties of outflows to the ones of the driving sources without biases. No grande-scale study of this type has been conducted so far, in particular none relying on a single, homogenous dataset covering a significant fraction of the local star formation. Our survey would, e.g., be critical in gauging the relative abundance of parsec-scale, ?S-shaped?, and quadrupolar outflows. This is important, given that such flows provide significant energy transfer over large (cloud-size) scales, possibly indicate jet precession, and may hint at protostellar binaries, respectively.

Goodman, Alyssa; Allen, Lori; Arce, Hector; Borkin, Michelle; Bourke, Tyler; Evans, Neal; Foster, Jonathan; Huard, Tracy; Kauffmann, Jens; Pineda, Jaime; Stapelfeldt, Karl

2007-05-01

278

2D and 3D Electrical Resistivity Tomography imaging of earthquake related ground deformations at the Ancient Roman Forum and Isis Temple of Baelo Claudia (Cádiz, South Spain).  

NASA Astrophysics Data System (ADS)

The ancient roman city of Baelo Claudia has been subject of several papers on earthquake environmental effects (EEE) and well as earthquake archaeological effects (EAE). During the field training course on archaeoseismology and palaeoseismology conducted in September 2009 (INQUA-IGCP567 Workshop) held at Baelo Claudia, four Electric Resistivity Tomography (ERT) profiles were carried out, by the teams of the Salamanca University (Spain), RWTH Aachen University (Germany) and the Geological Survey of Spain (IGME). ERT surveys were developed in the eastern side of the ancient roman Forum across the unexcavated sector of the archaeological site heading on the 1st Century AD Isis Temple. Each ERT profile was constituted by a 48 multielectrode array with spacing of 2 m resulting in a total length of investigation of around 384 m. ERT lines were separated 10 m each other resulting in a total research area of 3840 m2 to a mean investigation depth of 16 m. The selected survey configurations were Pole-Dipole and Wenner in order to get detailed information about lateral resistivity contrasts, but with a reasonable depth of investigation. The resulting 2D resistivity pseudosections clearly display deformations of the buried roman pavements which propagated in depth within the pre-roman clayey substratum of the Bolonia Bay area.. 3D modelling of the 2D pseudosections indicates that the observed deformations are related to near-surface landsliding, being possible to calculate the minimum volume of mobilized material. ERT 3D imaging allow to refine previous GPR surveys conducted at this same area and to get a subsurface picture of ground deformations caused by repeated earthquakes during the 1st and 3rd Centuries AD. Preliminary calculated volume for the mobilized materials affecting the foundations of the Isis Temple and Forum clearly points to a minimum ESI-07 VIII Intensity validating previous research in the zone. This study has been supported by the Spanish Research Projects ACI2008-0276 (USAL), CGL08-03998BTE (USAL), CGL08-04000BTE (MNCN, CSIC)

Silva, Pablo G.

2010-05-01

279

Spectrally edited 2D 13C-13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials.  

PubMed

Two robust combinations of spectral editing techniques with 2D (13)C-(13)C NMR have been developed for characterizing the aromatic components of (13)C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by (13)C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, C-H dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and C=O carbons, which is particularly useful for identifying furan and arene rings. The C=O carbons, whose chemical shifts vary strongly (between 212 and 165 ppm) and systematically depend on their two bonding partners, show particularly informative cross peaks, given that one bonding partner is defined by the other frequency coordinate of the cross peak. The new techniques and the information content of the resulting spectra are validated on sulfuric-acid treated low-temperature carbon materials and on products of the Maillard reaction. The crucial need for spectral editing for correct peak assignment is demonstrated in an example. PMID:23871898

Johnson, Robert L; Anderson, Jason M; Shanks, Brent H; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus

2013-09-01

280

Imaging Transverse Isotropic Properties of Muscle by Monitoring Acoustic Radiation Force Induced Shear Waves using a 2D Matrix Ultrasound Array  

PubMed Central

A 2D matrix ultrasound array is used to monitor acoustic radiation force impulse (ARFI) induced shear wave propagation in 3D in excised canine muscle. From a single acquisition, both the shear wave phase and group velocity can be calculated to estimate the shear wave speed (SWS) along and across the fibers, as well as the fiber orientation in 3D. The true fiber orientation found using the 3D Radon Transform on B-mode volumes of the muscle was used to verify the fiber direction estimated from shear wave data. For the simplified imaging case when the ARFI push can be oriented perpendicular to the fibers, the error in estimating the fiber orientation using phase and group velocity measurements was 3.5 ±2.6° and 3.4 ±1.4° (mean ± standard deviation), respectively, over six acquisitions in different muscle samples. For the more general case when the push is oblique to the fibers, the angle between the push and the fibers is found using the dominant orientation of the shear wave displacement magnitude. In 30 acquisitions on six different muscle samples with oblique push angles up to 40°, the error in the estimated fiber orientation using phase and group velocity measurements was 5.4±2.9° and 5.3±3.2°, respectively, after estimating and accounting for the additional unknown push angle. Either the phase or group velocity measurements can be used to estimate fiber orientation and SWS along and across the fibers. Although it is possible to perform these measurements when the push is not perpendicular to the fibers, highly oblique push angles induce lower shear wave amplitudes which can cause inaccurate SWS measurements. PMID:23686942

Wang, Michael; Byram, Brett; Palmeri, Mark; Rouze, Ned; Nightingale, Kathryn

2013-01-01

281

Temperature sensitivity of Cu K(alpha) imaging efficiency using a spherical Bragg reflecting crystal  

SciTech Connect

The Vulcan laser facility at the Rutherford Appleton Laboratory was used to study the interaction of a 75 J 10 ps, high intensity laser beam with low-mass solid, Cu targets. Two instruments were fielded as diagnostics of the Cu K-shell emission from the targets: A single photon counting CCD spectrometer provided the absolute K{sub {alpha}} yield and a spherically bent Bragg crystal recorded 2D monochromatic images with a spatial resolution of 10 {micro}m. Due to the shifting and broadening of the K{sub {alpha}} spectral lines with increasing temperature, there is a temperature dependence of the crystal collection efficiency. This provides a temperature diagnostic when cross calibrated against a single hit CCD spectrometer, and it affects measurements of the spatial pattern of electron transport. The experimental data showing changing collection efficiency are presented. The results are discussed in light of modeling of the temperature-dependent spectrum of Cu K-shell emission.

Akli, K U; Key, M H; Chung, H K; Hansen, S B; Freeman, R R; Chen, M H; Gregori, G; Hatchett, S; Hey, D; Izumi, N; King, J A; Kuba, J; Norreys, P; Mackinnon, A J; Murphy, C D; Snavely, R; Stepehens, R; Stoeckel, C; Theobald, W; Zhang, B

2006-08-07

282

Model capabilities, 2-D  

NASA Technical Reports Server (NTRS)

Two dimensional (2-D) atmospheric models provide results for altitude versus latitude as a function of time and are developed primarily for two reasons: to help understand atmospheric occurrences and to give assessments and/or make predictions of future changes in the atmosphere. Historically, the formulation of transport in 2-D models has been a difficult problem. Most current 2-D models have a transport that is either an Eulerian mean circulation with large stratospheric eddy diffusion or a residual (diabatic or Lagragian) mean circulation which typically is accompanied with small stratospheric eddy diffusion. Because of the assumption of zonal averaging, 2-D models are primarily useful in making predictions of atmospheric changes of time scales longer than a season. Although decadel atmospheric changes may be reasonably well represented with a 2-D model, the year to year changes which result from interannual transport differences, stratospheric warmings, semiannual oscillations, or quasi-biennial oscillations may not be well represented in the stratosphere and troposphere.

Jackman, Charles H.

1992-01-01

283

A COMPARISON OF 2D IMAGE ANALYSIS AND DESIGN-BASED STEREOLOGY FOR EVALUATING MORPHOLOGICAL AND ANATOMICAL CHANGES IN THE DOPAMINERGIC SYSTEM OF THE RODENT MIDBRAIN  

E-print Network

; chronic MPTP/probenecid PD (MPD) mouse model, alcohol preferring (AP) rat model, and the enriched environment (EE) rat model. 2D analyses and design-based stereology were used to quantify neuronal number, neuronal volume and regional volume. Student's t...

Park, Ji-Hyuk

2010-06-13

284

Reconstruction of 3D Surface Temperature from IR images  

Microsoft Academic Search

The aim of the present work is to develop a camera calibration technique for high-accuracy 3D vision metrology using IR thermal imagers. The final task is the reconstruction of 3D surface temperature from IR images (and, as a consequence, thermal fluxes) in wind tunnels. Particular attention is given to the application in hypersonic wind tunnel \\

G. Cardone; S. Discetti

285

Optimization of sample cooling temperature for redox cryo-imaging.  

PubMed

Cryo-imaging techniques have been widely used to measure the metabolic state of tissues by capturing reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) autofluorescence. However, NADH and FAD fluorescence is sensitive to changes in temperature, which may result in unreliable redox ratio calculations. Here, the relationship between the measured redox ratio and sample surface temperature was analyzed using a standard phantom solution and biological tissues. The results indicated that a temperature < - 100°C was a suitable cryo-imaging temperature window in which redox ratio measuring was immune to temperature fluctuations. These results may serve as a reference for designing and optimizing redox cryo-imaging experiments for quantitatively mapping the metabolic state of biological samples. PMID:25147959

Wang, Anle; Yuan, Jing; Luo, Weihua; Liu, Mengmeng; Luo, Qingming

2014-08-01

286

Automatic multimodal 2D/3D image fusion of ultrasound computer tomography and x-ray mammography for breast cancer diagnosis  

NASA Astrophysics Data System (ADS)

Breast cancer is the most common cancer among women. The established screening method to detect breast cancer in an early state is X-ray mammography. However, X-ray frequently provides limited contrast of tumors located within glandular tissue. A new imaging approach is Ultrasound Computer Tomography generating threedimensional volumes of the breast. Three different images are available: reflectivity, attenuation and speed of sound. The correlation of USCT volumes with X-ray mammograms is of interest for evaluation of the new imaging modality as well as for a multimodal diagnosis. Yet, both modalities differ in image dimensionality, patient positioning and deformation state of the breast. In earlier work we proposed a methodology based on Finite Element Method to register speed of sound images with the according mammogram. In this work, we enhanced the methodology to register all three image types provided by USCT. Furthermore, the methodology is now completely automated using image similarity measures to estimate rotations in datasets. A fusion methodology is proposed which combines the information of the three USCT image types with the X-ray mammogram via semitransparent overlay images. The evaluation was done using 13 datasets from a clinical study. The registration accuracy was measured by the displacement of the center of a lesion marked in both modalities. Using the automated rotation estimation, a mean displacement of 10.4 mm was achieved. Due to the clinically relevant registration accuracy, the methodology provides a basis for evaluation of the new imaging device USCT as well as for multimodal diagnosis.

Hopp, Torsten; Duric, Neb; Ruiter, Nicole V.

2012-03-01

287

Meniscal Calcifications: Morphologic and Quantitative Evaluation by using 2D Inversion-Recovery Ultrashort Echo Time and 3D Ultrashort Echo Time 3.0-T MR Imaging Techniques--Feasibility Study  

PubMed Central

Purpose: To assess the ability of ultrashort echo time (UTE) magnetic resonance (MR) imaging techniques to enable morphologic assessment of different types of meniscal calcifications, to compare these sequences with standard clinical sequences, and to perform T2* measurements of meniscal calcifications. Materials and Methods: This study was exempted by the institutional review board, and informed consent was not required. Ten human cadaveric menisci were imaged with high-spatial-resolution radiography and 3.0-T MR imaging by using morphologic (T1-weighted fast spin-echo [FSE], T2-weighted FSE, proton density [PD]-weighted FSE, two-dimensional [2D] fast spoiled gradient-echo [FSPGR], three-dimensional [3D] FSPGR, and 3D UTE) and quantitative (2D inversion-recovery [IR] UTE and 3D UTE) sequences. The menisci were divided into thirds for regional analysis. Morphologic assessment was performed with MR imaging; MR imaging findings were correlated with radiographs. Calcifications were classified as punctate, linear, or globular. T2* measurements were performed by manual placement of regions of interest (ROIs) in calcifications and by automatically creating ROIs in the surrounding tissues. Mixed-effects linear regression was used to determine variations in T2* as a function of region, morphology, and tissue type. Results: The two globular calcifications were visualized with all sequences. For punctate (n = 21) and linear (n = 21) calcifications, respectively, visibility rates were as follows: 9.5% for both with the T1-weighted FSE sequence, 0% for both with the T2-weighted FSE sequence, 19.0% and 23.8% with the PD-weighted FSE sequence, 0% for both with the 2D IR UTE sequence, 100% for both with the 3D UTE sequence, and 100% for both with the 3D FSPGR sequence. T2* values were significantly lower for calcifications than for the surrounding meniscal tissue (P < .001). There was a trend of globular calcifications having lower T2* values than other morphologies (P = .08). With the 2D IR UTE technique, the T2* of the globular calcifications tended to be lower than with the 3D UTE technique (0.13–0.16 vs 1.32–3.03 msec) (P = .14, analysis of variance). Conclusion: UTE MR imaging sequences may allow morphologic as well as quantitative evaluation of meniscal calcifications. © RSNA, 2012 PMID:22723564

Omoumi, Patrick; Bae, Won C.; Du, Jiang; Diaz, Eric; Statum, Sheronda; Bydder, Graeme M.

2012-01-01

288

Magnetic properties of quasi-2D antiferromagnet {N(n-C 5H 11) 4[Mn IIFe III(ox) 3]} ? below Néel temperature: revisited  

NASA Astrophysics Data System (ADS)

Magnetic measurements of {N(n-C 5H 11) 4[Mn IIFe III(ox) 3]} ? were carried out in the 5-300 K temperature range under different applied magnetic fields up to 50 kOe with zero-field-cooled (ZFC) and field-cooled (FC) modes. The FC and ZFC ?( T) plots exhibited a significantly large bifurcation below the transition temperature, which was traceable even at 50 kOe of applied magnetic field. The bifurcation temperature was found to be magnetic field dependent for the lower range of magnetic fields, which can be represented by a polynomial of magnetic field. The observed magnetic transition temperature of this compound was in good agreement with the earlier reported results. The isothermal magnetization curves below the magnetic transition temperature were found to deviate significantly from linearity above 30 kOe and above this field value became increasingly sigmoidal with decreasing temperature. This behavior might be associated with a magnetic field-induced transition in this compound.

Bhattacharjee, A.; Gütlich, P.

2004-01-01

289

Calibration source and temperature standard for passive millimetre wave imagers  

NASA Astrophysics Data System (ADS)

This paper discusses a practical and affordable approach to the accurate calibration of electronic beam-forming passive millimetre-wave imagers. With the aim of calibrating imagers with radiometric sensitivities ?T < 1 K, we have constructed a thermal radiation source at ambient temperature that fills the imager field-of-view at close range and can support several controllable thermal radiation sources to provide absolute and differential radiation temperature standards. Using a variety of temperature sensors, which have been extensively cross-calibrated against each other and a commercially provided calibration standard that is accurate to < 0.1 K, we have achieved absolute and relative calibration temperature uncertainties of less than 0.25 K.

Taylor, Chris T.; Scicluna, Peter; Wilkinson, Peter; Salmon, Neil

2010-10-01

290

A system for the complementary visualization of 3D volume images using 2D and 3D binaurally processed sonification representations  

Microsoft Academic Search

Typically, feedback from analysis of threedimensional volume image structures are presented in the visual domain. This ignores the potential for complementary analysis of feedback in the aural domain. This paper presents a system in which visualization of a volume image may be enhanced through repreaentation of the vozel structure by a sound sequence (termed a ‘aonification’) in which a sequence

David Rossiter; Wai-Yin Ng

1996-01-01

291

Comparison of 2D and 3D Imaging and Treatment Planning for Postoperative Vaginal Apex High-Dose Rate Brachytherapy for Endometrial Cancer  

SciTech Connect

Purpose: To evaluate bladder and rectal doses using two-dimensional (2D) and 3D treatment planning for vaginal cuff high-dose rate (HDR) in endometrial cancer. Methods and Materials: Ninety-one consecutive patients treated between 2000 and 2007 were evaluated. Seventy-one and 20 patients underwent 2D and 3D planning, respectively. Each patient received six fractions prescribed at 0.5 cm to the superior 3 cm of the vagina. International Commission on Radiation Units and Measurements (ICRU) doses were calculated for 2D patients. Maximum and 2-cc doses were calculated for 3D patients. Organ doses were normalized to prescription dose. Results: Bladder maximum doses were 178% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were no different than ICRU doses (p = 0.22). Two-cubic centimeter doses were 59% of maximum doses (p < 0.0001). Rectal maximum doses were 137% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 87% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 64% of maximum doses (p < 0.0001). Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final bladder dose to within 10% for 44%, 59%, 83%, 82%, and 89% of patients by using the ICRU dose, and for 45%, 55%, 80%, 85%, and 85% of patients by using the maximum dose, and for 37%, 68%, 79%, 79%, and 84% of patients by using the 2-cc dose. Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final rectal dose to within 10% for 100%, 100%, 100%, 100%, and 100% of patients by using the ICRU dose, and for 60%, 65%, 70%, 75%, and 75% of patients by using the maximum dose, and for 68%, 95%, 84%, 84%, and 84% of patients by using the 2-cc dose. Conclusions: Doses to organs at risk vary depending on the calculation method. In some cases, final dose accuracy appears to plateau after the third fraction, indicating that simulation and planning may not be necessary in all fractions. A clinically relevant level of accuracy should be determined and further research conducted to address this issue.

Russo, James K. [Department of Radiation Oncology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina (United States); Armeson, Kent E. [Division of Biostatistics and Epidemiology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina (United States); Richardson, Susan, E-mail: srichardson@radonc.wustl.edu [Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri (United States)

2012-05-01

292

Astronomical Parallax 2D  

NSDL National Science Digital Library

The Astronomical Parallax 2D Model illustrates the phenomenon of parallax in astronomy. Parallax is the apparent displacement of an object relative to the background that is caused by the motion of the observer (rather than the motion of the object itself, or of the background). This simulation illustrates the parallax of an object in space that results from the Earth's rotational or orbital motions. The simulation has two different modes. The default is an Earth Rotation Mode. In this mode the simulation illustrates the parallax caused by Earth's rotation on its axis. The top window shows an observer (indicated by a green dot) on the equator of Earth (blue disk). The green line shows that observer's line of sight to an object in space (indicated by a red dot). This line of sight extends to show where the object would appear against a more distant background. When the simulation is played the observer moves around the Earth as Earth rotates. Parallax causes the apparent position of the object to move back and forth between two extreme locations (indicated by open red circles). The bottom window shows the apparent motion of the object against the stars, as seen by the observer. [Note: to keep the simulation simple it is assumed that Earth's equator is aligned with the ecliptic plane (the plane of Earth's orbit). In actual fact they are tilted by 23.5 degrees, but this cannot be represented in a simple 2D simulation.] The other mode for the simulation is Earth Orbit Mode. In this mode the simulation illustrates the parallax caused by Earth's orbit around the Sun. Now the observer moves along Earth's orbital path (shown as a blue circle with the orange Sun in the center). The bottom window now shows the apparent motion of the Sun as well as that of the object being observed.

Timberlake, Todd

2011-05-18

293

Lectures on 2D gravity and 2D string theory  

Microsoft Academic Search

This report discusses the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity 1 -- path integral approach; 2D Euclidean quantum gravity 2 -- canonical approach; states in 2D string theory; matrix model technology 1 -- method of orthogonal polynomials; matrix model technology 2 -- loops on the lattice; matrix

P. Ginsparg; Gregory Moore

1992-01-01

294

Computed tomography imaging spectrometer (CTIS) with 2D reflective grating for ultraviolet to long-wave infrared detection especially useful for surveying transient events  

NASA Technical Reports Server (NTRS)

The optical system of this invention is an unique type of imaging spectrometer, i.e. an instrument that can determine the spectra of all points in a two-dimensional scene. The general type of imaging spectrometer under which this invention falls has been termed a computed-tomography imaging spectrometer (CTIS). CTIS's have the ability to perform spectral imaging of scenes containing rapidly moving objects or evolving features, hereafter referred to as transient scenes. This invention, a reflective CTIS with an unique two-dimensional reflective grating, can operate in any wavelength band from the ultraviolet through long-wave infrared. Although this spectrometer is especially useful for rapidly occurring events it is also useful for investigation of some slow moving phenomena as in the life sciences.

Wilson, Daniel W. (Inventor); Maker, Paul D. (Inventor); Muller, Richard E. (Inventor); Mouroulis, Pantazis Z. (Inventor)

2003-01-01

295

Computed Tomography Imaging Spectrometer (CTIS) with 2D Reflective Grating for Ultraviolet to Long-Wave Infrared Detection Especially Useful for Surveying Transient Events  

NASA Technical Reports Server (NTRS)

The optical system of this invention is an unique type of imaging spectrometer, i.e. an instrument that can determine the spectra of all points in a two-dimensional scene. The general type of imaging spectrometer under which this invention falls has been termed a computed-tomography imaging spectrometer (CTIS). CTIS's have the ability to perform spectral imaging of scenes containing rapidly moving objects or evolving features, hereafter referred to as transient scenes. This invention, a reflective CTIS with an unique two-dimensional reflective grating, can operate in any wavelength band from the ultraviolet through long-wave infrared. Although this spectrometer is especially useful for events it is also for investigation of some slow moving phenomena as in the life sciences.

Wilson, Daniel W. (Inventor); Maker, Paul D. (Inventor); Muller, Richard E. (Inventor); Mouroulis, Pantazis Z. (Inventor)

2003-01-01

296

GRAPHICS PROGRAMMING Section B Java 2D  

E-print Network

followed by Java 2D and then finally Java 3D. Abstract Window Toolkit The Abstract Window Toolkit (AWT.awt.font · java.awt.geom · java.awt.print · java.awt.image.renderable To be able to draw/render onto components

Hill, Gary

297

Resonant tunneling modulation in quasi-2D Cu2O/SnO2 p-n horizontal-multi-layer heterostructure for room temperature H2S sensor application  

PubMed Central

Heterostructure material that acts as resonant tunneling system is a major scientific challenge in applied physics. Herein, we report a resonant tunneling system, quasi-2D Cu2O/SnO2 p-n heterostructure multi-layer film, prepared by electrochemical deposition in a quasi-2D ultra-thin liquid layer. By applying a special half-sine deposition potential across the electrodes, Cu2O and SnO2 selectively and periodically deposited according to their reduction potentials. The as-prepared heterostructure film displays excellent sensitivity to H2S at room temperature due to the resonant tunneling modulation. Furthermore, it is found that the laser illumination could enhance the gas response, and the mechanism with laser illumination is discussed. It is the first report on gas sensing application of resonant tunneling modulation. Hence, heterostructure material act as resonant tunneling system is believed to be an ideal candidate for further improvement of room temperature gas sensing. PMID:23409241

Cui, Guangliang; Zhang, Mingzhe; Zou, Guangtian

2013-01-01

298

Temperature-driven disorder–order transitions in 2D copper-intercalated MoO3 revealed using dynamic transmission electron microscopy  

NASA Astrophysics Data System (ADS)

We demonstrate two different classes of disorder–order phase transitions in two-dimensional layered nanomaterial MoO3 intercalated with ?9–15 atomic percent zero-valent copper using conventional in situ electron diffraction and dynamic transmission electron microscopy. Heating to ?325 °C on a time scale of minutes produces a superlattice consistent with the formation of a charge density wave stabilized by nanometer-scale ordering of the copper intercalant. Unlike conventional purely electronic charge-density-wave states which form, reform, and disappear on picosecond scales as the temperature is changed, once it forms the observed structure in Cu–MoO3 is stable indefinitely over a very large temperature range (30 °C to the decomposition temperature of 450 °C). Nanosecond-scale heating to ?380–400 °C produced a completely different structure, replacing the disordered as-fabricated Cu–MoO3 with a much more crystallographically ordered metastable state that, according to a precession electron diffraction reconstruction, resembles the original MoO3 lattice apart from an asymmetric distortion that appears to expand parts of the van der Waals gaps to accommodate the copper intercalant. Control experiments in Cu-free material exhibited neither transformation, thus it appears the copper is a necessary part of the phase dynamics. This work shows how the combination of high-density metal atom intercalation and heat treatment over a wide range of time scales can produce nanomaterials of high crystalline quality in unique structural states that cannot be accessed through other methods.

Reed, Bryan W.; Chung, Frank R.; Wang, Mengjing; LaGrange, Thomas; Koski, Kristie J.

2014-12-01

299

Computer Vision for Fundamental Studies in Porous Media: Part I -- 2-D Image Acquisition and Processing for Microscopic Distribution of Oil, Water, and Pore Space Networks  

Microsoft Academic Search

Microscopic studies of the distributions of oil and water and of their networks in the pore space, at various relative saturations, are of fundamental importance in understanding migration, distribution, entrainment and mobilization of oil in the context of a particular (enhanced) oil recovery method. There has been an upsurge of interest in quantitative image analysis of pore morphology from two-dimensional

G. D. Yadav; I. F. Macdonald; I. Chatzis; F. A. L. Dullien

1986-01-01

300

From 2D slices to 3D volumes: Image based reconstruction and morphological characterization of hippocampal cells on charged and uncharged surfaces using FIB\\/SEM serial sectioning  

Microsoft Academic Search

3D imaging at a subcellular resolution is a powerful tool in the life sciences to investigate cells and their interactions with native tissues or artificial objects. While a tomographic experimental setup achieving a sufficient structural resolution can be established with either X-rays or electrons, the use of electrons is usually limited to very thin samples in transmission electron microscopy due

Franziska Schmidt; Markus Kühbacher; Ulrich Gross; Antonius Kyriakopoulos; Helmut Schubert; Rolf Zehbe

2011-01-01

301

Preliminary evidence for white matter metabolite differences in marijuana-dependent young men using 2D J-resolved magnetic resonance spectroscopic imaging at 4 Tesla  

Microsoft Academic Search

Chronic marijuana (MRJ) use is associated with altered cognition and mood state, altered brain metabolites, and 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

Marisa M. Silveri; John Eric Jensen; Isabelle M. Rosso; Jennifer T. Sneider; Deborah A. Yurgelun-Todd

2011-01-01

302

Image processing of a spectrogram produced by Spectrometer Airglow Temperature Imager  

Microsoft Academic Search

The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematics parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. An approach for image processing of registered spectrograms is proposed. A

Atanas Marinov Atanassov

2010-01-01

303

A comparative study of optical and radiative characteristics of X-ray-induced luminescent defects in Ag-doped glass and LiF thin films and their applications in 2-D imaging  

NASA Astrophysics Data System (ADS)

We report novel disk-type X-ray two-dimensional (2-D) imaging detectors utilising Ag-doped phosphate glass and lithium fluoride (LiF) thin films based on the radiophotoluminescence (RPL) and photoluminescence (PL) phenomena, respectively. The accumulated X-ray doses written in the form of atomic-scale Ag-related luminescent centres in Ag-doped glass and F-aggregated centres in LiF thin films were rapidly reconstructed as a dose distribution using a homemade readout system. The 2-D images reconstructed from the RPL and PL detectors are compared with that from the optically stimulated luminescence (OSL) detector. In addition, the optical and dosimetric characteristics of LiF thin films are investigated and evaluated. The possibilities of dose distributions with a high spatial resolution on the order of microns over large areas, a wide dynamic range covering 11 orders of magnitude and a non-destructive readout are successfully demonstrated by combining the Ag-doped glass with LiF thin films.

Kurobori, T.; Miyamoto, Y.; Maruyama, Y.; Yamamoto, T.; Sasaki, T.

2014-05-01

304

Three-dimensional (3D) microarchitecture correlations with 2D projection image gray-level variations assessed by trabecular bone score using high-resolution computed tomographic acquisitions: effects of resolution and noise.  

PubMed

The aim of the present study is to determine the level of correlation between the 3-dimensional (3D) characteristics of trabecular bone microarchitecture, as evaluated using microcomputed tomography (?CT) reconstruction, and trabecular bone score (TBS), as evaluated using 2D projection images directly derived from 3D ?CT reconstruction (TBS?CT). Moreover, we have evaluated the effects of image degradation (resolution and noise) and X-ray energy of projection on these correlations. Thirty human cadaveric vertebrae were acquired on a microscanner at an isotropic resolution of 93 ?m. The 3D microarchitecture parameters were obtained using MicroView (GE Healthcare, Wauwatosa, MI). The 2D projections of these 3D models were generated using the Beer-Lambert law at different X-ray energies. Degradation of image resolution was simulated (from 93 to 1488 ?m). Relationships between 3D microarchitecture parameters and TBS?CT at different resolutions were evaluated using linear regression analysis. Significant correlations were observed between TBS?CT and 3D microarchitecture parameters, regardless of the resolution. Correlations were detected that were strongly to intermediately positive for connectivity density (0.711 ? r² ? 0.752) and trabecular number (0.584 ? r² ? 0.648) and negative for trabecular space (-0.407 ? r² ? -0.491), up to a pixel size of 1023 ?m. In addition, TBS?CT values were strongly correlated between each other (0.77 ? r² ? 0.96). Study results show that the correlations between TBS?CT at 93 ?m and 3D microarchitecture parameters are weakly impacted by the degradation of image resolution and the presence of noise. PMID:22749406

Winzenrieth, Renaud; Michelet, Franck; Hans, Didier

2013-01-01

305

Liquid crystal imaging for temperature measurement of electronic devices  

Microsoft Academic Search

The liquid crystal imaging (LCI) technique has been shown to be a viable method for part level temperature measurement. The steps necessary to develop this capability and its sensitivity to various parameters are discussed and highlighted. Comparison of LCI and point measurement showed that high accuracy can be achieved with this method. The spatial resolution which plays a critical role

Kaveh Azar; John R. Benson; Vincent P. Manno

1991-01-01

306

Comparison of 2D Radiographic Images and 3D Cone Beam Computed Tomography for Positioning Head-and-Neck Radiotherapy Patients  

Microsoft Academic Search

Purpose: To assess the positioning accuracy using two-dimensional kilovoltage (2DkV) imaging and three-dimensional cone beam CT (CBCT) in patients with head and neck (H and N) cancer receiving radiation therapy. To assess the benefit of patient-specific headrest. Materials and Methods: All 21 patients studied were immobilized using thermoplastic masks with either a patient-specific vacuum bag (11 of 21, IMA) or

Heng Li; X. Ronald Zhu; Lifei Zhang; Lei Dong; Sam Tung; Anesa M. D. Ahamad; K. S. Clifford Chao; William H. Morrison; David I. Rosenthal; David L. Schwartz; Radhe Mohan; Adam S. Garden

2008-01-01

307

2-D High Resolution Seismic Imaging and Potential-Field Modeling of Small-Scale Intrabasin Faulting in Surprise Valley, California  

NASA Astrophysics Data System (ADS)

Surprise Valley, located in the northeast corner of California, constitutes the westernmost basin of the Basin and Range Province (BRP) and acts as a transition zone between the unextended Cenozoic volcanic rocks of the Modoc Plateau to the west and the extended BRP to the east. Previous seismic experiments undertaken in Surprise Valley to examine the structural setting of a developing extensional basin imaged the Surprise Valley Fault (SVF), the large-scale structure that controls the basin formation. In this study, we image small-scale structures associated with a prominent N-S-trending magnetic anomaly in the basin; these small-scale structures have no surface expression, yet they presumably play a role in the active geothermal system in the valley and may lend insight into the development of the basin. We recorded a total of 198 shots fired between geophones on a fixed linear array spanning ~ 1 km using a Betsy Seisgun source. The source yielded excellent penetration depths of up to 400 m, presumably due to the ideal conditions of fine-grained lake deposits saturated almost immediately below the surface. We used a standard seismic processing sequence to create an unmigrated time section, but lack of velocity control at depth led to the creation of a suite of different migrated images to explore the effects of strong lateral velocity variations in the subsurface. . Images obtained by applying Kirchhoff pre-stack depth migration to the seismic data reveal what we interpret to be an east-dipping (~56°) normal fault offsetting tilted strata of probable Oligocene age with ~250 meters of vertical throw. In addition to the 1 km seismic line, detailed gravity and magnetic surveys were undertaken to fully image the structure(s) north and south of the seismic line. The magnetic survey was performed with a cesium vapor total-field magnetometer installed on our newly developed all-terrain vehicle (ATV) magnetometer system, which was designed for efficient surveying in desert environments. The ATV’s induced magnetic field is accounted for by a heading correction, similar to that used in aeromagnetic surveys, and the overall noise level of the system is ~ 4 nT. We collected ~ 300 km of magnetic data in 2 days, imaging a 400 nT N-S-trending magnetic high. Modeling of the potential-field data confirms the interpretation of the seismic data of a buried east-dipping normal fault. Future potential-field modeling will look at whether this tectonic model can be applied north of the seismic line where the magnetic anomaly broadens significantly or whether an intrusive body is necessary, signaling contemporaneous volcanic activity with faulting. The outcome of our study validates our strategy of rapid potential-field profiling over large areas to identify specific targets for more intensive and expensive seismic profiles, the interpretation of which can be validated by detailed potential-field modeling.

Athens, N.; Fontiveros, V. C.; Klemperer, S. L.; Egger, A. E.; Glen, J. M.

2010-12-01

308

Imaging of broadband terahertz beams using an array of antenna-coupled microbolometers operating at room temperature.  

PubMed

We present results of 2D real-time imaging of terahertz (THz) beam generated by a photoconductive antenna driven by a femtosecond oscillator. The detector, operating at room temperature, is a 320 x 240 array of antenna-coupled microbolometers with integrated CMOS read-out electronics delivering 25 images per second. High quality images of broadband THz beams covering the 0.1-2 THz range are recorded while maintaining a signal-to-noise ratio of 10 for detected THz power as low as 25 nW. The compactness of the easy-to-use uncooled camera makes it very useful for the alignment of systems such as THz time-domain spectrometers and for the characterization of emitters, optics and other components. PMID:23482016

Oden, Jonathan; Meilhan, Jérome; Lalanne-Dera, Jérémy; Roux, Jean-François; Garet, Frédéric; Coutaz, Jean-Louis; Simoens, François

2013-02-25

309

Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography  

SciTech Connect

The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper we use time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river during high stage conditions. We demonstrate a modified time-lapse inversion approach, whereby the transient water table elevation is explicitly modeled by removing regularization constraints across the water table boundary. This implementation was critical for producing meaningful imaging results. We inverted approximately 1200 data sets (400 per line over 3 lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location of river water intrusion beneath each line. The results reveal non-uniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity ‘break through’ curves and longer river water residence times. The time-lapse ERT inversion approach removes the deleterious effects of changing water table elevation and enables remote and spatial continuous groundwater-river water exchange monitoring using surface based ERT arrays under conditions where groundwater and river water conductivity are in contrast.

Wallin, Erin L.; Johnson, Timothy C.; Greenwood, William J.; Zachara, John M.

2013-03-29

310

Lennard-Jones 2D Metropolis Model  

NSDL National Science Digital Library

The Lennard-Jones 2D Metropolis Model is a Monte Carlo simulation of Lennard-Jones particles in two dimensions in contact with a heat bath. The default initial condition is a rectangular configuration of N=64 particles in a box of length L = 18 and a temperature T= 1. The Lennard-Jones 2D Metropolis Model was developed using the Easy Java/JavaScript Simulations (EjsS) version 5 modeling tool. It is distributed as a ready-to-run (compiled) Java archive.

Christian, Wolfgang

2014-07-27

311

Synchrotron X-ray 2D and 3D Elemental Imaging of CdSe/ZnS Quantum dot Nanoparticles in Daphnia Magna  

SciTech Connect

The potential toxicity of nanoparticles to aquatic organisms is of interest given that increased commercialization will inevitably lead to some instances of inadvertent environmental exposures. Cadmium selenide quantum dots (QDs) capped with zinc sulfide are used in the semiconductor industry and in cellular imaging. Their small size (<10 nm) suggests that they may be readily assimilated by exposed organisms. We exposed Daphnia magna to both red and green QDs and used synchrotron X-ray fluorescence to study the distribution of Zn and Se in the organism over a time period of 36 h. The QDs appeared to be confined to the gut, and there was no evidence of further assimilation into the organism. Zinc and Se fluorescence signals were highly correlated, suggesting that the QDs had not dissolved to any extent. There was no apparent difference between red or green QDs, i.e., there was no effect of QD size. 3D tomography confirmed that the QDs were exclusively in the gut area of the organism. It is possible that the QDs aggregated and were therefore too large to cross the gut wall.

Jackson, B.; Pace, H; Lanzirotti, A; Smith, R; Ranville, J

2009-01-01

312

Microwave Imager Measures Sea Surface Temperature Through Clouds  

NASA Technical Reports Server (NTRS)

This image was acquired over Tropical Atlantic and U.S. East Coast regions on Aug. 22 - Sept. 23, 1998. Cloud data were collected by the Geostationary Operational Environmental Satellite (GOES). Sea Surface Temperature (SST) data were collected aboard the NASA/NASDA Tropical Rainfall Measuring Mission (TRMM) satellite by The TRMM Microwave Imager (TMI). TMI is the first satellite microwave sensor capable of accurately measuring sea surface temperature through clouds, as shown in this scene. For years scientists have known there is a strong correlation between sea surface temperature and the intensity of hurricanes. But one of the major stumbling blocks for forecasters has been the precise measurement of those temperatures when a storm begins to form. In this scene, clouds have been made translucent to allow an unobstructed view of the surface. Notice Hurricane Bonnie approaching the Carolina Coast (upper left) and Hurricane Danielle following roughly in its path (lower right). The ocean surface has been falsely colored to show a map of water temperature--dark blues are around 75oF, light blues are about 80oF, greens are about 85oF, and yellows are roughly 90oF. A hurricane gathers energy from warm waters found at tropical latitudes. In this image we see Hurricane Bonnie cross the Atlantic, leaving a cooler trail of water in its wake. As Hurricane Danielle followed in Bonnie's path, the wind speed of the second storm dropped markedly, as available energy to fuel the storm dropped off. But when Danielle left Bonnie's wake, wind speeds increased due to temperature increases in surface water around the storm. As a hurricane churns up the ocean, it's central vortex draws surface heat and water into the storm. That suction at the surface causes an upwelling of deep water. At depth, tropical ocean waters are significantly colder than water found near the surface. As they're pulled up to meet the storm, those colder waters essentially leave a footprint in the storm's wake which might last as long as two weeks. Forecasters can quantify the difference in surface temperatures between this footprint and the surrounding temperatures and use that information to better predict storm intensity. If another storm intersects with this cold water trail, it is likely to lose significant strength due to the fact that the colder water does not contain as much potential energy as warm water. TRMM Fact Sheet Predicting Hurricane Intensity Far from Land Remote Sensing Systems Image courtesy TRMM Project, Remote Sensing Systems, and Scientific Visualization Studio, NASA Goddard Space Flight Center

2002-01-01

313

Image processing of a spectrogram produced by Spectrometer Airglow Temperature Imager  

Microsoft Academic Search

The Spectral Airglow Temperature Imager is an instrument, specially designed\\u000afor investigation of the wave processes in the Mesosphere-Lower Thermosphere.\\u000aIn order to determine the kinematics parameters of a wave, the values of a\\u000aphysical quantity in different space points and their changes in the time\\u000ashould be known. An approach for image processing of registered spectrograms is\\u000aproposed. A

Atanas Marinov Atanassov

2010-01-01

314

Median Algorithm for Sector Spectra Calculation from Images Registered by the Spectral Airglow Temperature Imager  

E-print Network

The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematic parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. As a result of the possibilities of the SATI instrument for space scanning, different parts of the images (sectors of spectrograms) correspond to the respective mesopause areas (where the radiation is generated). An approach is proposed for sector spectra determination from SATI images based on ordered statistics instead of meaning. Comparative results are shown.

Atanassov, Atanas Marinov

2011-01-01

315

Image processing of a spectrogram produced by Spectrometer Airglow Temperature Imager  

E-print Network

The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematics parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. An approach for image processing of registered spectrograms is proposed. A detailed description is made of the steps of this approach, related to recovering CCD pixel values, influenced by cosmic particles, dark image correction and filter parameters determination.

Atanassov, Atanas Marinov

2010-01-01

316

Kalman Filtered MR Temperature Imaging for Laser Induced Thermal Therapies  

PubMed Central

The feasibility of using a stochastic form of Pennes bioheat model within a 3D finite element based Kalman filter (KF) algorithm is critically evaluated for the ability to provide temperature field estimates in the event of magnetic resonance temperature imaging (MRTI) data loss during laser induced thermal therapy (LITT). The ability to recover missing MRTI data was analyzed by systematically removing spatiotemporal information from a clinical MR-guided LITT procedure in human brain and comparing predictions in these regions to the original measurements. Performance was quantitatively evaluated in terms of a dimensionless L2 (RMS) norm of the temperature error weighted by acquisition uncertainty. During periods of no data corruption, observed error histories demonstrate that the Kalman algorithm does not alter the high quality temperature measurement provided by MR thermal imaging. The KF-MRTI implementation considered is seen to predict the bioheat transfer with RMS error < 4 for a short period of time, ?t < 10sec, until the data corruption subsides. In its present form, the KF-MRTI method currently fails to compensate for consecutive for consecutive time periods of data loss ?t > 10sec. PMID:22203706

Fuentes, D.; Yung, J.; Hazle, J. D.; Weinberg, J. S.; Stafford, R. J.

2013-01-01

317

Mars Tropospheric Temperatures from Near Infrared, Ground Based Spectral Imaging  

NASA Astrophysics Data System (ADS)

The spectral shapes of the 2 micron, 2? 1 + ? 3 atmospheric CO2 absorption bands, and nearby contributing hot bands and isotopic bands are all sensitive to temperatures in the lower atmosphere of Mars ( P > ˜1 mbar), via the rotational line intensities. This property allows tropospheric temperatures to be probed by ground-based spectral mapping techniques at moderate spectral resolving power. Telescopic measurements over a full hemisphere thus show diurnal temperature changes and atmospheric temperatures near the polar regions, neither of which can be easily measured by Mars orbiting thermal spectrometers. We describe K-band observations of Mars acquired on July 29 and Sept. 20, 2003 (Ls = 231 and 264), as part of an IRTF/SpeX observing campaign which bracketed the historic 2003 Mars opposition. Long slit grating spectra acquired at moderately high spatial resolution (80 to 130 km, sub-Earth) and spectral resolution (R= 1200 to 1500), were transformed to spatial-spectral (x, y, wavelength) image cubes following the method described by Glenar et al. (Icarus, 2003). Atmospheric temperatures are retrieved from the measurements by fitting to a multi parameter grid of surface-plus-atmosphere spectral reflectance models which incorporate gas parameters, simple representations for surface reflectance shape and dust opacity which is constrained by concurrent TES measurements. The retrievals are consistent with TES temperature measurements and allow extrapolation to polar latitudes as well as a range of local times. Funding for this work is provided by the NASA Planetary Astronomy Program.

Glenar, D. A.; Maguire, W. C.; Smith, M. D.; Bjoraker, G. L.; Pearl, J. C.; Blaney, D. L.

2004-11-01

318

A method for the retrieval of atomic oxygen density and temperature profiles from ground-based measurements of the O sup + ( sup 2 D minus sup 2 P) 7320- angstrom twilight airglow  

SciTech Connect

This paper describes a technique for the retrieval of altitude profiles of the atomic oxygen concentration (n = (O)) and temperature (T) from ground-based measurements of the {sup +}O({sup 2}D{minus}{sup 2}P) doublet at 7,320 and 7,330 {angstrom} in the twilight airglow. The technique is based on previously demonstrated knowledge that at solar zenith angles (SZA) characteristic of twilight conditions, the upper state of the 7,320-{angstrom} doublet transition is produced by photoionization and photoelectron impact ionization of atomic oxygen and lost mainly by radiative decay, thereby providing a sensitive dependence on (O). The authors apply inverse problem theory to retrieve the exospheric temperature T{sub {infinity}}, the atomic oxygen concentration at 120 km (n{sub 120}), the temperature at 120 km (T{sub 120}) and the temperature profile shape factor (S) using a Bates-Walker representation of n. The algorithm is tested and theoretically verified using synthetic data sets where random errors of measurements are characterized by Poisson noise due primarily to sky background. In the tests that they report here, the solar EUV flux is specified. By comparing retrieved with known input values, it is demonstrated that for the altitude range 200 to 500 km the atomic oxygen concentration (O) can be retrieved with relative errors {plus minus} 15% and systematic errors of about 25% if the solar EUV is given. Sensitivity of the results to noise, sample size (degrees of freedom), and absolute calibration are quantitatively evaluated. In addition, to demonstrate the validity of the technique experimentally, they utilized the Atmosphere Explorer E (AE-E) in situ measurements of the solar EUV flux and (O), with the latter taken when perigee was over Arecibo on an occasion when the observatory airglow spectrometer was simultaneously measuring the 7320-{angstrom} emission from the ground during twilight.

Fennelly, J.A.; Torr, D.G.; Richards, P.G. (Univ. of Alabama, Huntsville (USA)); Torr, M.R. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Sharp, W.E. (Univ. of Michigan, Ann Arbor (USA))

1991-02-01

319

2D Observers in 3D Object Recognition NEC Research Institute  

E-print Network

functions GRBF, 2D closest template matching that allows 2D a ne transformations of in- dependent 2D, still remains an area of strong debate. Previously, we showed that all models that allow rotations in the image plane of independent 2D templates could not account for human performance in discriminating novel

Kersten, Dan

320

Median Algorithm for Sector Spectra Calculation from Images Registered by the Spectral Airglow Temperature Imager  

Microsoft Academic Search

The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematic parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. As a result of the possibilities of the SATI instrument for

Atanas Marinov Atanassov

2011-01-01

321

Algorithm for Sector Spectra Calculation from Images Registered by the Spectral Airglow Temperature Imager  

Microsoft Academic Search

The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematic parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. As a result of the possibilities of the SATI instrument for

Atanas Marinov Atanassov

2010-01-01

322

Experimental Investigation of High Temperature Superconducting Imaging Surface Magnetometry  

SciTech Connect

The behavior of high temperature superconducting quantum interference devices (SQUIDs) in the presence of high temperature superconducting surfaces has been investigated. When current sources are placed close to a superconducting imaging surface (SIS) an image current is produced due to the Meissner effect. When a SQUID magnetometer is placed near such a surface it will perform in a gradiometric fashion provided the SQUID and source distances to the SIS are much less than the size of the SIS. We present the first ever experimental verification of this effect for a high temperature SIS. Results are presented for two SQUID-SIS configurations, using a 100 mm diameter YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} disc as the SIS. These results indicate that when the current source and sensor coil (SQUID) are close to the SIS, the behavior is that of a first-order gradiometer. The results are compared to analytic solutions as well as the theoretical predictions of a finite element model.

Espy, M.A.; Matlachov, A.N.; Kraus, R.H., Jr.

1999-06-21

323

Influence of high magnetic field strengths and parallel acquisition strategies on image quality in cardiac 2D CINE magnetic resonance imaging: comparison of 1.5 T vs. 3.0 T  

Microsoft Academic Search

The aim of this paper is to examine signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and image quality of cardiac CINE imaging at 1.5 T and 3.0 T. Twenty volunteers underwent cardiac magnetic resonance imaging (MRI) examinations using a 1.5-T and a 3.0-T scanner. Three different sets of breath-held, electrocardiogram-gated (ECG) CINE imaging techniques were employed, including: (1) unaccelerated SSFP (steady state

Matthias Gutberlet; Kerstin Schwinge; Patrick Freyhardt; Birgit Spors; Matthias Grothoff; Timm Denecke; Lutz Lüdemann; Ralph Noeske; Thoralf Niendorf; Roland Felix

2005-01-01

324

2-D pointing while walking  

Microsoft Academic Search

A frequent assertion in wearable computer discussions is that WIMP (windows\\/icons\\/mouse\\/pointer) interfaces are inappropriate for wearable computers, in part because 2-D (two-dimensional) pointing is difficult while walking. This paper summarizes findings from user studies conducted by Tangis Corporation on the usability of pointing devices for wearable computers. The author finds that, with changes, 2-D pointing could be an adequate interim

Lisa Louise Davis

2001-01-01

325

Spacecraft design project: High temperature superconducting infrared imaging satellite  

NASA Technical Reports Server (NTRS)

The High Temperature Superconductor Infrared Imaging Satellite (HTSCIRIS) is designed to perform the space based infrared imaging and surveillance mission. The design of the satellite follows the black box approach. The payload is a stand alone unit, with the spacecraft bus designed to meet the requirements of the payload as listed in the statement of work. Specifications influencing the design of the spacecraft bus were originated by the Naval Research Lab. A description of the following systems is included: spacecraft configuration, orbital dynamics, radio frequency communication subsystem, electrical power system, propulsion, attitude control system, thermal control, and structural design. The issues of testing and cost analysis are also addressed. This design project was part of the course Advanced Spacecraft Design taught at the Naval Postgraduate School.

1991-01-01

326

Limitations of using a thermal imager for snow pit temperatures  

NASA Astrophysics Data System (ADS)

Driven by temperature gradients, kinetic snow metamorphism is important for avalanche formation. Even when gradients appear to be insufficient for kinetic metamorphism, based on temperatures measured 10 cm apart, faceting close to a~crust can still be observed. Recent studies that visualized small scale (< 10 cm) thermal structures in a profile of snow layers with an infrared (IR) camera produced interesting results. The studies found melt-freeze crusts to be warmer or cooler than the surrounding snow depending on the large scale gradient direction. However, an important assumption within the studies was that a thermal photo of a freshly exposed snow pit was similar enough to the internal temperature of the snow. In this study, we tested this assumption by recording thermal videos during the exposure of the snow pit wall. In the first minute, the results showed increasing gradients with time, both at melt-freeze crusts and at artificial surface structures such as shovel scours. Cutting through a crust with a cutting blade or a shovel produced small concavities (holes) even when the objective was to cut a planar surface. Our findings suggest there is a surface structure dependency of the thermal image, which is only observed at times with large temperature differences between air and snow. We were able to reproduce the hot-crust/cold-crust phenomenon and relate it entirely to surface structure in a temperature-controlled cold laboratory. Concave areas cooled or warmed slower compared with convex areas (bumps) when applying temperature differences between snow and air. This can be explained by increased radiative transfer or convection by air at convex areas. Thermal videos suggest that such processes influence the snow temperature within seconds. Our findings show the limitations of the use of a thermal camera for measuring pit-wall temperatures, particularly in scenarios where large gradients exist between air and snow and the interaction of snow pit and atmospheric temperatures are enhanced. At crusts or other heterogeneities, we were unable to create a sufficiently homogenous snow pit surface and non-internal gradients appeared at the exposed surface. The immediate adjustment of snow pit temperature as it reacts with the atmosphere complicates the capture of the internal thermal structure of a snowpack even with thermal videos. Instead, the shown structural dependency of the IR signal may be used to detect structural changes of snow caused by kinetic metamorphism. The IR signal can also be used to measure near surface temperatures in a homogenous new snow layer.

Schirmer, M.; Jamieson, B.

2013-10-01

327

Limitations of using a thermal imager for snow pit temperatures  

NASA Astrophysics Data System (ADS)

Driven by temperature gradients, kinetic snow metamorphism plays an import role in avalanche formation. When gradients based on temperatures measured 10 cm apart appear to be insufficient for kinetic metamorphism, faceting close to a crust can be observed. Recent studies that visualised small-scale (< 10 cm) thermal structures in a profile of snow layers with an infrared (IR) camera produced interesting results. The studies found melt-freeze crusts to be warmer or cooler than the surrounding snow depending on the large-scale gradient direction. However, an important assumption within these studies was that a thermal photo of a freshly exposed snow pit was similar enough to the internal temperature of the snow. In this study, we tested this assumption by recording thermal videos during the exposure of the snow pit wall. In the first minute, the results showed increasing gradients with time, both at melt-freeze crusts and artificial surface structures such as shovel scours. Cutting through a crust with a cutting blade or shovel produced small concavities (holes) even when the objective was to cut a planar surface. Our findings suggest there is a surface structure dependency of the thermal image, which was only observed at times during a strong cooling/warming of the exposed pit wall. We were able to reproduce the hot-crust/cold-crust phenomenon and relate it entirely to surface structure in a temperature-controlled cold laboratory. Concave areas cooled or warmed more slowly compared with convex areas (bumps) when applying temperature differences between snow and air. This can be explained by increased radiative and/or turbulent energy transfer at convex areas. Thermal videos suggest that such processes influence the snow temperature within seconds. Our findings show the limitations of using a thermal camera for measuring pit-wall temperatures, particularly during windy conditions, clear skies and large temperature differences between air and snow. At crusts or other heterogeneities, we were unable to create a sufficiently planar snow pit surface and non-internal gradients appeared at the exposed surface. The immediate adjustment of snow pit temperature as it reacts with the atmosphere complicates the capture of the internal thermal structure of a snowpack with thermal videos. Instead, the shown structural dependency of the IR signal may be used to detect structural changes of snow caused by kinetic metamorphism. The IR signal can also be used to measure near surface temperatures in a homogenous new snow layer.

Schirmer, M.; Jamieson, B.

2014-03-01

328

Television image transmission from close quarters of a high-temperature object  

NASA Astrophysics Data System (ADS)

A new Chinese patent 'micropore imager of industrial television supervision' is introduced in this paper. Three ways of transmission is compared. The author invent a flame- proof 'micropore imager' to image close quarters high- temperature at normal temperature area, obtain 'first image' then use television-camera to shoot the image into television system, transmit it to supervision center. The micropore imager is based on the principle of small aperture imaging and it applies image sharpening technology to make image fitting for supervision requirements, it also attaches accessories to prevent blocking. This method has been proved by doing experiments on boilers in power station.

Ge, Zhaoxiang; Su, Jingni; Min, Qingfeng

1996-10-01

329

ESR in 2D triangular chromium lattices  

NASA Astrophysics Data System (ADS)

The spin dynamics in some two-dimensional (2D) triangular Cr-antiferromagnetic frustrated lattices, i.e. HCrO2, LiCrO2, and NaCrO2 with ordered rock-salt structure as well as the delafossite compounds CuCrO2 and AgCrO2, has been investigated by Electron Spin Resonance (ESR). On approaching the Néel temperature TN from above, the divergence of the temperature dependent linewidth is well described in terms of a Berezinskii-Kosterlitz-Thouless (BKT) like scenario due to magnetic vortex-antivortex pairing.

Hemmida, M.; Krug von Nidda, H.-A.; Loidl, A.

2010-01-01

330

TOPAZ2D. 2D FEM Heat Transfer & E&M Field Code  

SciTech Connect

TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.

Shapiro, A.B. [Lawrence Livermore National Lab., CA (United States)

1987-04-01

331

Comparison of ultrasound temperature imaging with infrared thermometry during radio frequency ablation  

NASA Astrophysics Data System (ADS)

Radio frequency ablation (RFA) is a widely used alternative modality in the treatment of tumors. During RFA, temperature monitoring is essential to ensure accurate and appropriate thermal dosage. Ultrasound temperature imaging based on the detection of echo time-shift has been demonstrated to have good ability to monitor the temperature distribution. However, no study has proven that the region of ultrasound temperature imaging can correspond well to the practical temperature distribution in the tissue. In this study, we aim to combine ultrasound and infrared systems to clarify the correlation between ultrasound temperature imaging and the practical temperature distribution in a tissue. Five porcine livers (n = 5) were ablated using an RFA system and monitored with an ultrasound system to acquire raw backscattered data for temperature imaging. Meanwhile, an infrared imaging system was used to obtain the practical temperature map of the tissue. The results showed that the temperature distribution detected by ultrasound echo time-shift agreed with those obtained from the infrared image. When the tissue temperature was higher than 45 °C, ultrasound temperature imaging is difficult to describe the behavior of the heat transfer in a homogeneous medium. In this study, we used the experimental setup based on combining ultrasound and infrared systems to confirm the reliability and limitations of ultrasound temperature imaging in RFA monitoring. Such an experimental design may be considered as an indispensable platform for the development and optimization of ultrasound temperature imaging techniques in RFA monitoring.

Geng, Xiaonan; Zhou, Zhuhuang; Li, Qiang; Wu, Shuicai; Wang, Chiao-Yin; Liu, Hao-Li; Chuang, Ching-Cheng; Tsui, Po-Hsiang

2014-04-01

332

Algorithm for Sector Spectra Calculation from Images Registered by the Spectrometer Airglow Temperature Imager  

Microsoft Academic Search

The Spectral Airglow Temperature Imager is an instrument, specially designed\\u000afor investigation of the wave processes in the Mesosphere-Lower Thermosphere.\\u000aIn order to determine the kinematic parameters of a wave, the values of a\\u000aphysical quantity in different space points and their changes in the time\\u000ashould be known. As a result of the possibilities of the SATI instrument for

Atanas Marinov Atanassov

2010-01-01

333

General 2D phase correction method for interleaved EPI reconstruction  

NASA Astrophysics Data System (ADS)

Interleaved echo-planar imaging (EPI) and spiral imaging are two fast clinical magnetic resonance imaging (MRI) schemes that obtain k-space signal more efficiency for encoding an object. Since points along their k-space trajectories are from different echo times that may carry different phase and amplified errors originating from the static magnetic field inhomogeneity and nuclear spin relaxation, to form an image free of artifacts, both phase and amplitude errors need to be compensated properly in the image reconstruction. To address this issue, we have develop a general image reconstruction technique which is capable of accomplishing 2D phase correction for image reconstruction of interleaved EPI and spiral data. In this technique we formulated the image reconstructions as a problem of finding an optical solution to a set of linear algebraic equations corresponding to a specific imaging measurement. Furthermore, the phase errors, as well as other constraints known of the image, can be incorporated into these equations. The final solution can be obtained by solving the equation via an iterative procedure, free of k-space data gridding. Images with 2D phase correction have been successfully reconstructed using a set of imaging data acquired on a clinical MRI scanner. The significance of the work is that it has demonstrated that the 2D spatial phase correction can be accomplished for a set of interleaved EPI acquisition. Also, this is a flexible image reconstruction method for further improving the resulting image quality.

Liu, Haiying

1998-11-01

334

Fluorescence-Doped Particles for Simultaneous Temperature and Velocity Imaging  

NASA Technical Reports Server (NTRS)

Polystyrene latex microspheres (PSLs) have been used for particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) measurements for several decades. With advances in laser technologies, instrumentation, and data processing, the capability to collect more information about fluid flow beyond velocity is possible using new seed materials. To provide additional measurement capability, PSLs were synthesized with temperature-sensitive fluorescent dyes incorporated within the particle. These multifunctional PSLs would have the greatest impact if they could be used in large scale facilities with minimal modification to the facilities or the existing instrumentation. Consequently, several potential dyes were identified that were amenable to existing laser systems currently utilized in wind tunnels at NASA Langley Research Center as well as other wind and fluid (water) tunnels. PSLs incorporated with Rhodamine B, dichlorofluorescein (DCF, also known as fluorescein 548 or fluorescein 27) and other dyes were synthesized and characterized for morphology and spectral properties. The resulting particles were demonstrated to exhibit fluorescent emission, which would enable determination of both fluid velocity and temperature. They also would allow near-wall velocity measurements whereas laser scatter from surfaces currently prevents near-wall measurements using undoped seed materials. Preliminary results in a wind tunnel facility located at Virginia Polytechnic Institute and State University (Virginia Tech) have verified fluorescent signal detection and temperature sensitivity of fluorophore-doped PSLs.

Danehy, Paul M.; Tiemsin, Pacita I.; Wohl, Chrostopher J.; Verkamp, Max; Lowe, T.; Maisto, P.; Byun, G.; Simpson, R.

2012-01-01

335

The 2D ?-Dirac oscillator  

NASA Astrophysics Data System (ADS)

In this Letter, 2D Dirac oscillator in the quantum deformed framework generated by the ?-Poincaré-Hopf algebra is considered. The problem is formulated using the ?-deformed Dirac equation. The resulting theory reveals that the energies and wave functions of the oscillator are modified by the deformation parameter.

Andrade, Fabiano M.; Silva, Edilberto O.

2014-11-01

336

Infrared imaging of the surface temperature field of water during film spreading  

E-print Network

Infrared imaging of the surface temperature field of water during film spreading J. R. Saylor and G. These images were converted to surface temperature fields. The amount of turbulent structure present- namics can in turn change the surface temperature field, a quantity which is relevant to several

Saylor, John R.

337

Algorithm for Sector Spectra Calculation from Images Registered by the Spectrometer Airglow Temperature Imager  

E-print Network

The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematic parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. As a result of the possibilities of the SATI instrument for space scanning, different parts of the images (sectors of spectrograms) correspond to the respective mesopause areas (where the radiation is generated). Algorithms for sector spectra calculation are proposed. In contrast to the original algorithms where twelve sectors with angles of 30 degrees are only determined now sectors with arbitrary orientation and angles are calculated. An algorithm is presented for sector calculation based on pixel division into sub pixels. A comparative results are shown.

Atanassov, Atanas Marinov

2010-01-01

338

Estimation of radiative properties and temperature distributions in coal-fired boiler furnaces by a portable image processing system  

SciTech Connect

This paper presented an experimental investigation on the estimation of radiative properties and temperature distributions in a 670 t/h coal-fired boiler furnace by a portable imaging processing system. The portable system has been calibrated by a blackbody furnace. Flame temperatures and emissivities were measured by the portable system and equivalent blackbody temperatures were deduced. Comparing the equivalent blackbody temperatures measured by the portable system and the infrared pyrometer, the relative difference is less than 4%. The reconstructed pseudo-instantaneous 2-D temperature distributions in two cross-sections can disclose the combustion status inside the furnace. The measured radiative properties of particles in the furnace proved there is significant scattering in coal-fired boiler furnaces and it can provide useful information for the calculation of radiative heat transfer and numerical simulation of combustion in coal-fired boiler furnaces. The preliminary experimental results show this technology will be helpful for the combustion diagnosis in coal-fired boiler furnaces. (author)

Li, Wenhao; Lou, Chun; Sun, Yipeng; Zhou, Huaichun [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, 430074 Hubei (China)

2011-02-15

339

2D packing using the Myriad framework  

NASA Astrophysics Data System (ADS)

Myriad is a framework for building networked and distributed vision systems and is described in a companion paper in this conference. Myriad allows the components of a multi-camera, multi-user vision system (web-cameras, image processing engines, intelligent device controllers, databases and the user interface terminals) to be interconnected and operated together, even if they are physically separated by many hundreds, or thousands, of kilometres. This is achieved by operating them as Internet services. The principal objective in this article is to illustrate the simplicity of harmonising visual control with an existing system using Myriad. However, packing of 2-dimensional blob-like objects is of considerable commercial importance in some industries and involves robotic handling and/or cutting. The shapes to be packed may be cut from sheet metal, glass, cloth, leather, wood, card, paper, composite board, or flat food materials. In addition, many 3D packing applications can realistically be tackled only by regarding them as multi-layer 2D applications. Using Myriad to perform 2D packing, a set of blob-like input objects ("shapes") can be digitised using a standard camera (e.g. a "webcam"). The resulting digital images are then analysed, using a separate processing engine, perhaps located on a different continent. The packing is planned by another processing system, perhaps on a third continent. Finally, the assembly is performed using a robot, usually but not necessarily, located close to the camera.

Chatburn, Luke T.; Batchelor, Bruce G.

2004-02-01

340

Brightness Temperature Map Reconstruction from Dual-Polarimetric Visibilities in Synthetic Aperture Imaging Radiometry  

Microsoft Academic Search

Synthetic aperture imaging radiometers are powerful sensors for high-resolution observations of the Earth at low microwave frequencies. Within this context, the European Space Agency is currently developing the soil moisture and ocean salinity (SMOS) mission devoted to the monitoring of SMOS at global scale from L-band spaceborne radiometric observations obtained with a 2-D interferometer. This paper is concerned with the

Eric Anterrieu; Ali Khazaal

2008-01-01

341

Tree visualization with Tree-maps: A 2-d space-filling approach  

Microsoft Academic Search

this paper deals with a two-dimensional (2-d) space-fillingapproach in which each node is a rectangle whose area is proportional to some attribute suchas node size.Research on relationships between 2-d images and their representation in tree structures hasfocussed on node and link representations of 2-d images. This work includes quad-trees(Samet, 1989) and their variants which are important in image processing. The

Ben Shneiderman

1991-01-01

342

Restoring 2D content from distorted documents.  

PubMed

This paper presents a framework to restore the 2D content printed on documents in the presence of geometric distortion and non-uniform illumination. Compared with textbased document imaging approaches that correct distortion to a level necessary to obtain sufficiently readable text or to facilitate optical character recognition (OCR), our work targets nontextual documents where the original printed content is desired. To achieve this goal, our framework acquires a 3D scan of the document's surface together with a high-resolution image. Conformal mapping is used to rectify geometric distortion by mapping the 3D surface back to a plane while minimizing angular distortion. This conformal "deskewing" assumes no parametric model of the document's surface and is suitable for arbitrary distortions. Illumination correction is performed by using the 3D shape to distinguish content gradient edges from illumination gradient edges in the high-resolution image. Integration is performed using only the content edges to obtain a reflectance image with significantly less illumination artifacts. This approach makes no assumptions about light sources and their positions. The results from the geometric and photometric correction are combined to produce the final output. PMID:17848773

Brown, Michael S; Sun, Mingxuan; Yang, Ruigang; Yun, Lin; Seales, W Brent

2007-11-01

343

Human Erythrocyte Catalase: 2-D Crystal Nucleation and Production of Multiple Crystal Forms  

Microsoft Academic Search

Negatively stained electron microscope images are presented, showing the nucleation of two-dimensional (2-D) crystals of human erythrocyte catalase produced on mica by the negative staining-carbon film technique. Examples of the formation of partially ordered 2-D arrays and more ordered 2-D crystals are shown and the conditions required for the production of large well-ordered 2-D crystals discussed. The structural transformation of

J. Robin Harris; Andreas Holzenburg

1995-01-01

344

The conceptual design of an electron cyclotron emission imaging system for studying ITER-like high temperature plasmas  

NASA Astrophysics Data System (ADS)

The design of an electron cyclotron emission imaging (ECEI) system for two-dimensional (2D) observation of the magnetohydrodynamical modes in high temperature ITER (from ‘International Thermonuclear Experimental Reactor’) H-mode-like plasmas (5.3 T and 25 keV) based on fundamental ordinary mode (O1-mode) and second-harmonic extraordinary mode (X2-mode) measurements is explored conceptually. For studying the spatial resolution in high temperature plasmas, the relativistic broadening and inward shift of the emission layer in the mid-plane are calculated. The radial spatial resolution is significantly degraded in the range R < 5.1 m for the O1-mode and in the range R < 6.9 m for the X2-mode. The region with R < 6.5 m is inaccessible for X2-mode study. The emission layer width is enlarged in a narrow region of the pedestal due to the magnetic field being modified by the large pressure gradient. The broadening and shift in the poloidal plane are also calculated, to investigate their effects on 2D measurements. The frequency range of electron cyclotron emission measurements is selected to protect the system from stray radiations of the 170 GHz electron cyclotron resonance heating source and to avoid harmonic overlap. The frequency ranges of 115–160 GHz for the O1-mode and 230–320 GHz for the X2-mode provide radial coverage of 5.9 < R < 8.2 m or ?0.15 < r/a < 1.The ECEI system utilizes a dual-array detection technique which provides a simultaneous measurement at two radial positions, and each array has 8 by 16 (radial by vertical) channels. The radial image size with 8 channels is ?41–76 cm for the O1-mode and ?19–36 cm for the X2-mode, with sufficient resolution. The front-end optics, which focuses the electron cyclotron emission to the low loss corrugated transmission waveguides, is designed with two flat mirrors and two focusing mini-lens arrays. The vertical image size with 16 channels is ?150 cm and the spot size of each channel is 8–15 cm in the plasma region, taking into account the sensitivity pattern of the waveguide. The refraction effect due to inhomogeneous plasma enlarges the vertical image size up to 20% and 5% for the O1-mode and X2-mode cases, respectively. The horizontal distortion due to the relativistic inwards shift is reduced by the increased toroidal field in the core region.

Lee, W.; Yun, G. S.; Park, H. K.; Nam, Y. B.; Seon, C. R.

2014-09-01

345

Two-Dimensional Thin Layer Chromatography (2D-TLC) 1. Resuspend RNA pellet in 5 l ddH2O. Place at room temperature for 5-15 minutes. Use pipette tip  

E-print Network

119 Two-Dimensional Thin Layer Chromatography (2D-TLC) 1. Resuspend RNA pellet in 5 µl ddH2O. Place: AMP, A9272; CMP, C1133; GMP, G3628; UMP, U1126. 4. Mark origin on chromatography plate using a pencil, no indicator (from VWR). 5. Spot sample on chromatography plate at origin. Do 0.1 - 0.2 µl at a time. Dry

Aris, John P.

346

Average centreline temperatures of a buoyant pool fire obtained by image processing of video recordings  

Microsoft Academic Search

Images from a standard video camera are used to obtain an average centreline temperature distribution of simulated pool fires. By using a novel technique, characteristic length scales are extracted from the flame images. With this information and the use of empirical correlations, the mean centreline temperature distribution is obtained. The range of validity of this technique is determined by conducting

L. Audouin; G. Kolb; J. L. Torero; J. M. Most

1995-01-01

347

2D quasiperiodic plasmonic crystals  

PubMed Central

Nanophotonic structures with irregular symmetry, such as quasiperiodic plasmonic crystals, have gained an increasing amount of attention, in particular as potential candidates to enhance the absorption of solar cells in an angular insensitive fashion. To examine the photonic bandstructure of such systems that determines their optical properties, it is necessary to measure and model normal and oblique light interaction with plasmonic crystals. We determine the different propagation vectors and consider the interaction of all possible waveguide modes and particle plasmons in a 2D metallic photonic quasicrystal, in conjunction with the dispersion relations of a slab waveguide. Using a Fano model, we calculate the optical properties for normal and inclined light incidence. Comparing measurements of a quasiperiodic lattice to the modelled spectra for angle of incidence variation in both azimuthal and polar direction of the sample gives excellent agreement and confirms the predictive power of our model. PMID:23209871

Bauer, Christina; Kobiela, Georg; Giessen, Harald

2012-01-01

348

2D quasiperiodic plasmonic crystals.  

PubMed

Nanophotonic structures with irregular symmetry, such as quasiperiodic plasmonic crystals, have gained an increasing amount of attention, in particular as potential candidates to enhance the absorption of solar cells in an angular insensitive fashion. To examine the photonic bandstructure of such systems that determines their optical properties, it is necessary to measure and model normal and oblique light interaction with plasmonic crystals. We determine the different propagation vectors and consider the interaction of all possible waveguide modes and particle plasmons in a 2D metallic photonic quasicrystal, in conjunction with the dispersion relations of a slab waveguide. Using a Fano model, we calculate the optical properties for normal and inclined light incidence. Comparing measurements of a quasiperiodic lattice to the modelled spectra for angle of incidence variation in both azimuthal and polar direction of the sample gives excellent agreement and confirms the predictive power of our model. PMID:23209871

Bauer, Christina; Kobiela, Georg; Giessen, Harald

2012-01-01

349

2D quasiperiodic plasmonic crystals  

NASA Astrophysics Data System (ADS)

Nanophotonic structures with irregular symmetry, such as quasiperiodic plasmonic crystals, have gained an increasing amount of attention, in particular as potential candidates to enhance the absorption of solar cells in an angular insensitive fashion. To examine the photonic bandstructure of such systems that determines their optical properties, it is necessary to measure and model normal and oblique light interaction with plasmonic crystals. We determine the different propagation vectors and consider the interaction of all possible waveguide modes and particle plasmons in a 2D metallic photonic quasicrystal, in conjunction with the dispersion relations of a slab waveguide. Using a Fano model, we calculate the optical properties for normal and inclined light incidence. Comparing measurements of a quasiperiodic lattice to the modelled spectra for angle of incidence variation in both azimuthal and polar direction of the sample gives excellent agreement and confirms the predictive power of our model.

Bauer, Christina; Kobiela, Georg; Giessen, Harald

2012-12-01

350

Variational regularized 2-D nonnegative matrix factorization.  

PubMed

A novel approach for adaptive regularization of 2-D nonnegative matrix factorization is presented. The proposed matrix factorization is developed under the framework of maximum a posteriori probability and is adaptively fine-tuned using the variational approach. The method enables: (1) a generalized criterion for variable sparseness to be imposed onto the solution; and (2) prior information to be explicitly incorporated into the basis features. The method is computationally efficient and has been demonstrated on two applications, that is, extracting features from image and separating single channel source mixture. In addition, it is shown that the basis features of an information-bearing matrix can be extracted more efficiently using the proposed regularized priors. Experimental tests have been rigorously conducted to verify the efficacy of the proposed method. PMID:24806120

Gao, Bin; Woo, W L; Dlay, S S

2012-05-01

351

Imaging informatics based on method of MR temperature measurement in high-intensity focused ultrasound  

NASA Astrophysics Data System (ADS)

MR imaging has been used to perform imaging guided high-intensity focused ultrasound (HIFU) and meanwhile can also be used precisely to measure tissue temperature in theory. But in practice, the temperature environment and target are complex. Therefore, it is difficult to measure targeted temperature just by simply using the theory of numerical calculation based on MR image information. In this presentation, we presented new MR temperature measurement, based on imaging informatics, to measure the targeted tissue temperature in MR imaging guided HIFU therapeutic procedure. By heating up the water phantom experiments under HIFU, the new algorithm gives a satisfactory result compared with existing algorithm. Based on experimental data, we can see the accuracy increase 37.5% from 0.4048? up to 0.2530? when we choose new algorithms.

Chen, Xiangjiao; Zhang, Jianguo

2014-03-01

352

Lennard-Jones 2D Demon Model  

NSDL National Science Digital Library

The Lennard-Jones 2D Demon Model is a Monte Carlo simulation of Lennard-Jones particles in two dimensions interacting with a Monte Carlo demon. A Monte Carlo demon is an extra degree of freedom that is allowed to transfer energy as it attempts to change the state of the system. The demon keeps track of its own energy and can take or give energy to a particle as it interacts with a randomly chosen particle. Because the demon cannot have negative energy, the total energy of the system remains constant -- as it should in the microcanonical ensemble. The demon is, in effect, a thermometer. Its extra degree of freedom perturbs the system very little and the average demon energy is proportional to the temperature of the system. (See Statistical and Thermal Physics notes by H. Gould and J. Tobochnik.) The Lennard-Jones 2D Demon Model was developed using the Easy Java/JavaScript Simulations (EjsS) version 5 modeling tool. It is distributed as a ready-to-run (compiled) Java archive.

Christian, Wolfgang

2014-08-01

353

Downscaling of Aircraft, Landsat, and MODIS-based Land Surface Temperature Images with Support Vector Machines  

Microsoft Academic Search

High spatial resolution Land Surface Temperature (LST) images are required to estimate evapotranspiration (ET) at a field scale for irrigation scheduling purposes. Satellite sensors such as Landsat 5 Thematic Mapper (TM) and Moderate Resolution Imaging Spectroradiometer (MODIS) can offer images at several spectral bandwidths including visible, near-infrared (NIR), shortwave-infrared, and thermal-infrared (TIR). The TIR images usually have coarser spatial resolutions

W. Ha; P. H. Gowda; T. Oommen; T. A. Howell; J. E. Hernandez

2010-01-01

354

Ultrafast 2D IR Vibrational Echo Spectroscopy  

E-print Network

Ultrafast 2D IR Vibrational Echo Spectroscopy JUNRONG ZHENG, KYUNGWON KWAK, AND M. D. FAYER The experimental technique and applications of ultrafast two- dimensional infrared (2D IR) vibrational echo systems. The form and time evolution of the 2D IR spectrum permits examination of processes that cannot

Fayer, Michael D.

355

2D Static Light Scattering for Dairy Based Applications  

E-print Network

2D Static Light Scattering for Dairy Based Applications Jacob Lercke Skytte Kongens Lyngby 2014 Ph an exploratory study in relation to dairy based applications, with a major emphasis on the microstructure. The presented was financed by the Centre for Imaging Food Quality project, which is funded by the Danish Council

356

Linearization of electrostatically actuated surface micromachined 2-D optical scanner  

Microsoft Academic Search

This paper presents an effective method of linearizing the electrostatic transfer characteristics of micromachined two-dimensional (2-D) scanners. The orthogonal scan angles of surface micromachined polysilicon scanner are controlled by using quadrant electrodes for electrostatic actuation. By using a pair of differential voltages over a bias voltage, we could improve the distortion of projected images from 72% to only 13%. A

Hiroshi Toshiyoshi; Wibool Piyawattanametha; Cheng-Ta Chan; Ming C. Wu

2001-01-01

357

Recursive Segmentation and Recognition Templates for 2D Parsing  

E-print Network

Recursive Segmentation and Recognition Templates for 2D Parsing Long (Leo) Zhu CSAIL MIT leozhu formulated in terms of parsing the input signal into a hierarchical representation. Natural language- time parsing algorithms. By contrast, the two-dimensional nature of images makes it much harder

Yuille, Alan L.

358

Three-dimensional temperature imaging around a gold microwire  

NASA Astrophysics Data System (ADS)

We report on the temperature mapping around a resistively heated gold microwire. The temperature is determined by measuring the thermal-induced distortion of an incident optical wavefront crossing the system. The optical technique we introduce herein allows, in addition to 3-dimensional temperature measurements, a retrieval of the heat source density at optical resolution. Experimental results are supported by finite element simulations and electric measurements. Applications are envisioned in microelectronics, microfluidics, or nanochemistry.

Bon, Pierre; Belaid, Nadia; Lagrange, Denis; Bergaud, Christian; Rigneault, Hervé; Monneret, Serge; Baffou, Guillaume

2013-06-01

359

Predicting 3D People from 2D Pictures  

Microsoft Academic Search

We propose a hierarchical process for inferring the 3D pose of a per- son from monocular images. First we infer a learned view-based 2D body model from a single image using non-parametric belief propagation. This approach integrates information from bottom-up body-part proposal processes and deals with self-occlusion to compute distributions over limb poses. Then, we exploit a learned Mixture of

Leonid Sigal; Michael J. Black

2006-01-01

360

A Planar Quantum Transistor Based on 2D-2D Tunneling in Double Quantum Well Heterostructures  

SciTech Connect

We report on our work on the double electron layer tunneling transistor (DELTT), based on the gate-control of two-dimensional -- two-dimensional (2D-2D) tunneling in a double quantum well heterostructure. While previous quantum transistors have typically required tiny laterally-defined features, by contrast the DELTT is entirely planar and can be reliably fabricated in large numbers. We use a novel epoxy-bond-and-stop-etch (EBASE) flip-chip process, whereby submicron gating on opposite sides of semiconductor epitaxial layers as thin as 0.24 microns can be achieved. Because both electron layers in the DELTT are 2D, the resonant tunneling features are unusually sharp, and can be easily modulated with one or more surface gates. We demonstrate DELTTs with peak-to-valley ratios in the source-drain I-V curve of order 20:1 below 1 K. Both the height and position of the resonant current peak can be controlled by gate voltage over a wide range. DELTTs with larger subband energy offsets ({approximately} 21 meV) exhibit characteristics that are nearly as good at 77 K, in good agreement with our theoretical calculations. Using these devices, we also demonstrate bistable memories operating at 77 K. Finally, we briefly discuss the prospects for room temperature operation, increases in gain, and high-speed.

Baca, W.E.; Blount, M.A.; Hafich, M.J.; Lyo, S.K.; Moon, J.S.; Reno, J.L.; Simmons, J.A.; Wendt, J.R.

1998-12-14

361

A critique of methods for temperature imaging in single cells.  

PubMed

We argue that standard thermodynamic considerations and scaling laws show that a single cell cannot substantially raise its temperature by endogenous thermogenesis. This statement seriously questions the interpretations of recent work reporting temperature heterogeneities measured in single living cells. PMID:25166869

Baffou, Guillaume; Rigneault, Hervé; Marguet, Didier; Jullien, Ludovic

2014-09-01

362

Temperature profile of the infrared image Heat exchange between  

E-print Network

method: A (periodic) heat flux is forced onto the water surface and the change of temperature at the ocean surface forces the surface temperature to deviate a few tenths of a degree from the bulk measurements will be conducted and compared with radar measurements of the sea surface roughness and with gas

Jaehne, Bernd

363

CSY3019 -Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50%)  

E-print Network

application is to include a Java 2D graphical representation of a disc rotor. A partial image of the disc% of the screen height. · AffineTransform used to translate, rotate, scale, shear, or perform a combination of the 'Additional functionality/complexity' above. Figure 2: Disc Rotor. #12;Technical Report The report should

Hill, Gary

364

Research on some influence factors in high temperature measurement of metal with thermal infrared imager  

NASA Astrophysics Data System (ADS)

Thermal infrared imagers have been introduced into the research field of metal processing temperature in recent years, such as the workpiece's and the tool's temperatures in metal machining. However, these metal components are usually non-black body with unknown and varied surface emissivities, plus the in-line processing environment also effects the measurement of infrared imager. Hereby, accurately measuring metal processing temperature with infrared imager becomes a challenge. In this paper, the temperature measurement formula of infrared imager is analyzed first, and next the experimental devices designed by the authors is introduced, then several influences on the temperature measurement, such as low temperature and high temperature backgrounds with high emissivity, object area / viewing field ratio, and the shooting angel, are experimentally investigated with a thermal infrared imager. The results indicate that a low temperature background with high emissivity and a small object area / viewing field ratio, as well as a shooting direction perpendicular to the measured surface, can improve the measurement accuracy. This work provides a useful reference for the temperature measurement in metal processing.

Yanming, QUAN; Hao, XU; Zhiyong, KE

365

Characterization of photocathode dark current vs. temperature in image intensifier tube modules and intensified televisions  

NASA Astrophysics Data System (ADS)

Image intensifiers (I2) have gained wide acceptance throughout the Army as the premier nighttime mobility sensor for the individual soldier, with over 200,000 fielded systems. There is increasing need, however, for such a sensor with a video output, so that it can be utilized in remote vehicle platforms, and/or can be electronically fused with other sensors. The image-intensified television (I2TV), typically consisting of an image intensifier tube coupled via fiber optic to a solid-state imaging array, has been the primary solution to this need. I2TV platforms in vehicles, however, can generate high internal heat loads and must operate in high-temperature environments. Intensifier tube dark current, called "Equivalent Background Input" or "EBI", is not a significant factor at room temperature, but can seriously degrade image contrast and intra-scene dynamic range at such high temperatures. Cooling of the intensifier's photocathode is the only practical solution to this problem. The US Army RDECOM CERDEC Night Vision & Electronic Sensors Directorate (NVESD) and Ball Aerospace have collaborated in the reported effort to more rigorously characterize intensifier EBI versus temperature. NVESD performed non-imaging EBI measurements of Generation 2 and 3 tube modules over a large range of ambient temperature, while Ball performed an imaging evaluation of Generation 3 I2TVs over a similar temperature range. The findings and conclusions of this effort are presented.

Bender, Edward J.; Wood, Michael V.; Hart, Steve; Heim, Gerald B.; Torgerson, John A.

2004-10-01

366

Influence of processing temperature on the image transfer characteristics of an image guide made of polymer optical fibers  

Microsoft Academic Search

An image guide has been made by using polymer optical fibers. Single-strand polymer optical fibers were laid out first in\\u000a a square array, and the square bundle thus made was fused in a vacuum oven at various processing temperatures. Although the\\u000a line resolution of an image guide is determined by the number of optical fibers per unit area (i.e., the

Byung-Wook Park; Do-Young Yoon

2008-01-01

367

Acoustic tomographic imaging of temperature and flow fields in air  

NASA Astrophysics Data System (ADS)

Acoustic travel-time tomography is a remote sensing technique that uses the dependence of sound speed in air on temperature and wind speed along the sound propagation path. Travel-time measurements of acoustic signals between several sound sources and receivers travelling along different paths through a measuring area give information on the spatial distribution of temperature and flow fields within the area. After a separation of the two influences, distributions of temperature and flow can be reconstructed using inverse algorithms. As a remote sensing method, one advantage of acoustic travel-time tomography is its ability to measure temperature and flow field quantities without disturbing the area under investigation due to insertion of sensors. Furthermore, the two quantities—temperature and flow velocity—can be recorded simultaneously with this measurement method. In this paper, an acoustic tomographic measurement system is introduced which is capable of resolving three-dimensional distributions of temperature and flow fields in air within a certain volume (1.3 m × 1.0 m × 1.2 m) using 16 acoustic transmitter-receiver pairs. First, algorithms for the 3D reconstruction of distributions from line-integrated measurements are presented. Moreover, a measuring apparatus is introduced which is suited for educational purposes, for demonstration of the method as well as for indoor investigations. Example measurements within a low-speed wind tunnel with different incident flow situations (e.g. behind bluff bodies) using this system are shown. Visualizations of the flow illustrate the plausibility of the tomographically reconstructed flow structures. Furthermore, alternative individual measurement methods for temperature and flow speed provide comparable results.

Barth, Manuela; Raabe, Armin

2011-03-01

368

Image quality improvements of electronic portal imaging devices by multi-level gain calibration and temperature correction.  

PubMed

Amorphous silicon (aSi:H) flat panel detectors are prevalent in radiotherapy for megavoltage imaging tasks. Any clinical and dosimetrical application requires a well-defined dose response of the system to achieve meaningful results. Due to radiation damages, panels deteriorate and the linearity of pixel response to dose as well as the stability with regard to changing operating temperatures get worse with time. Using a single level gain correction can lead to an error of about 23% when irradiating a flood field image with 100 MU min(-1) on an old detector. A multi-level gain (MLG) correction is introduced, emending the nonlinearities and subpanel-related artifacts caused by insufficient radiation hardness of amplifiers in the read-out electronics. With rising temperature, offset values typically increase (up to 300 gray values) while the response at higher dose values per frame remain constant for a majority of pixels. To account for temperature-related image artifacts, two additional temperature correction methods have been developed. MLG in combination with temperature corrections can re-establish the aSi:H image quality to the performance required by reliable medical verification tools. Furthermore, the life span and recalibration intervals of these costly devices can be prolonged decisively. PMID:23999060

Huber, S; Mooslechner, M; Mitterlechner, B; Weichenberger, H; Serpa, M; Sedlmayer, F; Deutschmann, H

2013-09-21

369

Image quality improvements of electronic portal imaging devices by multi-level gain calibration and temperature correction  

NASA Astrophysics Data System (ADS)

Amorphous silicon (aSi:H) flat panel detectors are prevalent in radiotherapy for megavoltage imaging tasks. Any clinical and dosimetrical application requires a well-defined dose response of the system to achieve meaningful results. Due to radiation damages, panels deteriorate and the linearity of pixel response to dose as well as the stability with regard to changing operating temperatures get worse with time. Using a single level gain correction can lead to an error of about 23% when irradiating a flood field image with 100 MU min-1 on an old detector. A multi-level gain (MLG) correction is introduced, emending the nonlinearities and subpanel-related artifacts caused by insufficient radiation hardness of amplifiers in the read-out electronics. With rising temperature, offset values typically increase (up to 300 gray values) while the response at higher dose values per frame remain constant for a majority of pixels. To account for temperature-related image artifacts, two additional temperature correction methods have been developed. MLG in combination with temperature corrections can re-establish the aSi:H image quality to the performance required by reliable medical verification tools. Furthermore, the life span and recalibration intervals of these costly devices can be prolonged decisively.

Huber, S.; Mooslechner, M.; Mitterlechner, B.; Weichenberger, H.; Serpa, M.; Sedlmayer, F.; Deutschmann, H.

2013-09-01

370

Temperature imaging of vortex-flame interaction by filtered Rayleigh scattering.  

SciTech Connect

This paper describes the application of a filtered-Rayleigh-scattering (FRS) instrument for nonintrusive temperature imaging in a vortex-driven diffusion flame. The FRS technique provides quantitative, spatially correlated temperature data without the flow intrusion or time lag associated with physical probes. Use of a molecular iodine filter relaxes the requirement for clean, particulate-free flowfields and offers the potential for imaging near walls, test section windows and in sooty flames, all of which are preculded in conventional Rayleigh imaging, where background interference from these sources typically overwhelms the weak molecular scattering signal. For combustion applications, FRS allows for full-field temperature imaging without chemical seeding of the flowfield, which makes FRS an attractive alternative to other laser-based imaging methods such as planar laser-induced fluorescencs (PLIF). In this work, the details of our FRS imaging system are presented and temperature measurements from an acoustically forced diffusion flame are provided. The local Rayleigh crosssection is corrected using Raman imaging measurements of the methane fuel molecule, which are then correlated to other major species using a laminar flamelet approach. To our knowledge, this is the first report of joint Raman/FRS imaging for nonpremixed combustion. Measurements are presented from flames driven at 7.5 Hz, where a single vortex stretches the flame, and at 90 Hz, where two consecutive vortices interact to cause a repeatable strain-induced flame-quenching event.

Beresh, Steven Jay; Grasser, Thomas W.; Kearney, Sean Patrick; Schefer, Robert W. (Sandia National Laboratories, Livermore, CA)

2003-08-01

371

MAGNUM2D. Radionuclide Transport Porous Media  

SciTech Connect

MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water/rock system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent porous continuum, a system of discrete, unfilled, and interconnecting fractures separated by impervious rock mass, and a low permeability porous continuum with several discrete, unfilled fractures traversing the medium. The calculations assume local thermodynamic equilibrium between the rock and groundwater, nonisothermal Darcian flow in the continuum portions of the rock, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.

Langford, D.W. [Boeing Computer Services, Richland, WA (United States); Baca, R.G. [EG and G Idaho Inc., Idaho Falls, ID (United States)

1989-03-01

372

MAGNUM2D. Radionuclide Transport Porous Media  

SciTech Connect

MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water/rock system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent porous continuum, a system of discrete, unfilled, and interconnecting fractures separated by impervious rock mass, and a low permeability porous continuum with several discrete, unfilled fractures traversing the medium. The calculation assumes local thermodynamic equilibrium between the rock and groundwater, nonisothermal Darcian flow in the continuum portions of the rock, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.

Langford, D.W. [Boeing Computer Services, Richland, WA (United States); Baca, R.G. [EG and G Idaho Inc., Idaho Falls, ID (United States)

1988-08-01

373

On 2D impurity radiation fronts  

NASA Astrophysics Data System (ADS)

In [1] a strongly radiated impurity radiation front in magnetized plasma was investigated with simple 2D reaction-diffusion equation where perpendicular and parallel heat conduction coefficients were assumed to be the functions of temperature, K_allel=K_allel (T)>> K_?= K_?(T). It was shown that when the ratio K_allel (T)/K_? (T) increases with increasing T, a strongly radiated V-shaped radiation front (spread along the magnetic field lines) can be formed and perpendicular transport plays a key role in the magnitude of the radiation loss in spite of the inequality K_allel >> K_?. Here we generalize the results of Ref. 1 to the case when K_? depends on both temperature and radial derivative of T, which model anomalous perpendicular heat transport in magnetized plasmas. We present a criterion of V-shaped front formation and consider structural stability of such front. [1] S.I. Krasheninnikov, A.A. Batishcheva, D.J. Sigmar, EPS-97. *Also at Kurchatov Institute, Russia

Simakov, A. M.; Krasheninnikov, S. I.

1997-11-01

374

Ratiometric Temperature Imaging Using Environment-Insensitive Luminescence of Mn-Doped Core/Shell Nanocrystals  

PubMed Central

We report a ratiometric temperature imaging method based on Mn luminescence from Mn-doped CdS/ZnS nanocrystals (NCs) with controlled doping location, which is designed to exhibit strong temperature dependence of the spectral lineshape while being insensitive to the surrounding chemical environment. Ratiometric thermometry on Mn luminescence spectrum was performed by using Mn-doped CdS/ZnS core/shell NCs that have a large local lattice strain on Mn site, which results in the enhanced temperature dependence of the bandwidth and peak position. Mn luminescence spectral lineshape is highly robust with respect to the change in the polarity, phase and pH of the surrounding medium and aggregation of the NCs, showing great potential in temperature imaging under chemically heterogeneous environment. The temperature sensitivity (?IR/IR = 0.5%/K at 293 K, IR = intensity ratio at two different wavelengths) is highly linear in a wide range of temperatures from cryogenic to above-ambient temperatures. We demonstrate the surface temperature imaging of a cyro-cooling device showing the temperature variation of >200 K by imaging the luminescence of the NC film formed by simple spin coating, taking advantage of the environment-insensitive luminescence. PMID:23629731

Park, Yerok; Koo, Chiwan; Chen, Hsiang-Yun; Han, Arum; Son, Dong Hee

2013-01-01

375

Temperature Dependence Study of Noncontact Afm Images Using Molecular Dynamics Simulations  

NASA Astrophysics Data System (ADS)

The effect of temperature on the noncontact atomic force microscopy (NC-AFM) surface imaging is investigated with the aid of molecular dynamics (MD) analysis based on the Sutton-Chen (SC) interatomic potential. Particular attention is devoted to the tip and sample flexibility at different temperatures. When a gold coated probe is brought close to the Au (001) surface at high temperatures, the tip and surface atoms are pulled together and their distance becomes smaller. The tip and sample atoms displacement varies in the different environment temperatures and this leads to the different interaction forces. Along this line, to study the effect of temperature on the resulting images, we have employed the well-known NC-AFM model and carried out realistic non-equilibrium MD 3D simulations of atomic scale imaging at different close approach positions to the surface.

Nejat Pishkenari, Hossein; Meghdari, Ali

376

TOPAZ. 2D Finite Element Heat Conduction Code  

SciTech Connect

TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.

Shapiro, A.B. [Lawrence Livermore National Lab., CA (United States)

1985-01-01

377

CH2D(+), the search for the holy grail.  

PubMed

CH2D+, the singly deuterated counterpart of CH3(+), offers an alternative way to mediate formation of deuterated species at temperatures of several tens of Kelvin, as compared to the release of deuterated species from grains. We report a longstanding observational search for this molecular ion, whose rotational spectroscopy is not yet completely secure. We summarize the main spectroscopic properties of this molecule and discuss the chemical network leading to the formation of CH2D+, with explicit account of the ortho/para forms of H2, H3(+), and CH3(+). Astrochemical models support the presence of this molecular ion in moderately warm environments at a marginal level. PMID:23627602

Roueff, Evelyne; Gerin, Maryvonne; Lis, Dariusz C; Wootten, Alwyn; Marcelino, Nuria; Cernicharo, Jose; Tercero, Belen

2013-10-01

378

Motion Compensation for Temperature Imaging using the Change in Ultrasonic Backscattered Energy  

E-print Network

of CBE for ultrasonic thermometry. One limitation in measuring temperature-dependent CBE from ultrasoundMotion Compensation for Temperature Imaging using the Change in Ultrasonic Backscattered Energy for noninvasive thermometry to enhance tumor treatment using hyperthermia. Our theoretical model [1] predicted

Arthur, R. Martin

379

Measurement of temperature distributions across laser-heated samples by multispectral imaging radiometry  

E-print Network

1 Measurement of temperature distributions across laser-heated samples by multispectral imaging is tested by measuring the melting point of Pt at 1 bar, and measuring laser- heated Fe at 20 GPa of measuring temperature distributions can be generalized to other hot objects besides laser heated spots. #12

Campbell, Andrew

380

Localized regulatory frequencies of human skin temperature derived from the analysis of series of infrared images  

Microsoft Academic Search

The physiological function of human skin in body temperature regulation is reviewed, and methods for measuring skin temperature are described. Different ways to extract diagnostic data from thermal images, focusing on dynamic studies that provide valuable information on the physiological and pathological functions of the autonomous nervous system, are presented. Using fast-Fourier-transform analysis, the frequencies of the different regulatory processes

Michael Anbar; Sean D'Arcy

1991-01-01

381

Comparison of calculation models for determination of the mesopause temperature using SATI images  

Microsoft Academic Search

The Spectral Airglow Temperature Imager is an instrument for ground-based spectroscopic measurements of the night-glow atmosphere emissions. This instrument was developed specially for gravity wave investigation. The measured airglow spectra are matched to synthetic spectra calculated in advance for determination of the temperature in the mesopause region where the radiation maximum of some ?2 emissions is situated. The synthetic spectra

Atanas Marinov Atanassov

2011-01-01

382

Concurrent OH imager and sodium temperature//wind lidar observation of localized ripples over northern Colorado  

E-print Network

Concurrent OH imager and sodium temperature//wind lidar observation of localized ripples over by a dynamic instability at 88.5 km. The ripples clearly advected as packets with the background wind. Lidar temperature/wind lidar observation of localized ripples over northern Colorado, J. Geophys. Res., 110, D13110

383

2D\\/3D registration for X-ray guided bronchoscopy using distance map classification  

Microsoft Academic Search

In X-ray guided bronchoscopy of peripheral pulmonary lesions, airways and nodules are hardly visible in X-ray images. Transbronchial biopsy of peripheral lesions is often carried out blindly, resulting in degraded diagnostic yield. One solution of this problem is to superimpose the lesions and airways segmented from preoperative 3D CT images onto 2D X-ray images. A feature-based 2D\\/3D registration method is

Di Xu; Sheng Xu; Daniel A. Herzka; Rex C. Yung; Martin Bergtholdt; Luis F. Gutiérrez; Elliot R. McVeigh

2010-01-01

384

Novel 3D ultrasound image-based biomarkers based on a feature selection from a 2D standardized vessel wall thickness map: a tool for sensitive assessment of therapies for carotid atherosclerosis  

NASA Astrophysics Data System (ADS)

With the advent of new therapies and management strategies for carotid atherosclerosis, there is a parallel need for measurement tools or biomarkers to evaluate the efficacy of these new strategies. 3D ultrasound has been shown to provide reproducible measurements of plaque area/volume and vessel wall volume. However, since carotid atherosclerosis is a focal disease that predominantly occurs at bifurcations, biomarkers based on local plaque change may be more sensitive than global volumetric measurements in demonstrating efficacy of new therapies. The ultimate goal of this paper is to develop a biomarker that is based on the local distribution of vessel-wall-plus-plaque thickness change (VWT-Change) that has occurred during the course of a clinical study. To allow comparison between different treatment groups, the VWT-Change distribution of each subject must first be mapped to a standardized domain. In this study, we developed a technique to map the 3D VWT-Change distribution to a 2D standardized template. We then applied a feature selection technique to identify regions on the 2D standardized map on which subjects in different treatment groups exhibit greater difference in VWT-Change. The proposed algorithm was applied to analyse the VWT-Change of 20 subjects in a placebo-controlled study of the effect of atorvastatin (Lipitor). The average VWT-Change for each subject was computed (i) over all points in the 2D map and (ii) over feature points only. For the average computed over all points, 97 subjects per group would be required to detect an effect size of 25% that of atorvastatin in a six-month study. The sample size is reduced to 25 subjects if the average were computed over feature points only. The introduction of this sensitive quantification technique for carotid atherosclerosis progression/regression would allow many proof-of-principle studies to be performed before a more costly and longer study involving a larger population is held to confirm the treatment efficacy.

Chiu, Bernard; Li, Bing; Chow, Tommy W. S.

2013-09-01

385

High-speed color imaging and ratio temperature radiometer by multispectral optics  

NASA Astrophysics Data System (ADS)

In order to analyze mechanism of melting and deformation of metal while it is being rapidly heating, or a combusion process, it is important not only to measure the time displacement of a sample and its acceleration, but to measure the change in the temperature distribution of the sample over time. For this purpose, we have developed a new Multi-Spectral Optics. By mounting combining a high-speed camera with our Multi-Spectral Optics system, we have successfully acquired a temperature distribution map and its color image simultaneously. In our system, a color image is composed with three spectrum images from wavelengths, 450 nm, 550 nm and 750 nm. A temperature distribution map can be created from two images in the near infra-red wavelengths, 750 nm and 850 nm, which were obtained by applying the ratio temperature pyrometry method. However, in order to observe and analyze rapid deformation of a sample, it is important to capture vivid images in color. This task requires additional external light. Since a high intensity of emitted light will cause an error in temperature, it is very difficult correctly to measure temperature and deformation of the sample at the same time. Temperature measured with near infra-red lights is not be influenced by the external surrounding light. In particular, for taking photos of welding phenomena, it is possible to capture clear images with excessive lighting without affecting temperature measurement. Moreover, in combustion phenomenon, it is possible to avoid the influence of chemiluminescence caused by radicals such as C2 in flame.

Usui, Hiroyuki; Takeuchi, Shinji; Ohno, Yoshio; Mitsui, Kenji

2003-07-01

386

Mechanical characterization of 2D, 2D stitched, and 3D braided/RTM materials  

NASA Technical Reports Server (NTRS)

Braided composite materials have potential for application in aircraft structures. Fuselage frames, floor beams, wing spars, and stiffeners are examples where braided composites could find application if cost effective processing and damage tolerance requirements are met. Another important consideration for braided composites relates to their mechanical properties and how they compare to the properties of composites produced by other textile composite processes being proposed for these applications. Unfortunately, mechanical property data for braided composites do not appear extensively in the literature. Data are presented in this paper on the mechanical characterization of 2D triaxial braid, 2D triaxial braid plus stitching, and 3D (through-the-thickness) braid composite materials. The braided preforms all had the same graphite tow size and the same nominal braid architectures, (+/- 30 deg/0 deg), and were resin transfer molded (RTM) using the same mold for each of two different resin systems. Static data are presented for notched and unnotched tension, notched and unnotched compression, and compression after impact strengths at room temperature. In addition, some static results, after environmental conditioning, are included. Baseline tension and compression fatigue results are also presented, but only for the 3D braided composite material with one of the resin systems.

Deaton, Jerry W.; Kullerd, Susan M.; Portanova, Marc A.

1993-01-01

387

Improving Image Quality by Accounting for Changes in Water Temperature during a Photoacoustic Tomography Scan  

PubMed Central

The emerging field of photoacoustic tomography is rapidly evolving with many new system designs and reconstruction algorithms being published. Many systems use water as a coupling medium between the scanned object and the ultrasound transducers. Prior to a scan, the water is heated to body temperature to enable small animal imaging. During the scan, the water heating system of some systems is switched off to minimize the risk of bubble formation, which leads to a gradual decrease in water temperature and hence the speed of sound. In this work, we use a commercially available scanner that follows this procedure, and show that a failure to model intra-scan temperature decreases as small as 1.5°C leads to image artifacts that may be difficult to distinguish from true structures, particularly in complex scenes. We then improve image quality by continuously monitoring the water temperature during the scan and applying variable speed of sound corrections in the image reconstruction algorithm. While upgrading to an air bubble-free heating pump and keeping it running during the scan could also solve the changing temperature problem, we show that a software correction for the temperature changes provides a cost-effective alternative to a hardware upgrade. The efficacy of the software corrections was shown to be consistent across objects of widely varying appearances, namely physical phantoms, ex vivo tissue, and in vivo mouse imaging. To the best of our knowledge, this is the first study to demonstrate the efficacy of modeling temporal variations in the speed of sound during photoacoustic scans, as opposed to spatial variations as focused on by previous studies. Since air bubbles pose a common problem in ultrasonic and photoacoustic imaging systems, our results will be useful to future small animal imaging studies that use scanners with similarly limited heating units. PMID:23071512

Van de Sompel, Dominique; Sasportas, Laura Sarah; Dragulescu-Andrasi, Anca; Bohndiek, Sarah; Gambhir, Sanjiv Sam

2012-01-01

388

Prediction of the thermal imaging minimum resolvable (circle) temperature difference with neural network application.  

PubMed

Thermal imaging is an important technology in both national defense and the private sector. An advantage of thermal imaging is its ability to be deployed while fully engaged in duties, not limited by weather or the brightness of indoor or outdoor conditions. However, in an outdoor environment, many factors, including atmospheric decay, target shape, great distance, fog, temperature out of range and diffraction limits can lead to bad image formation, which directly affects the accuracy of object recognition. The visual characteristics of the human eye mean that it has a much better capacity for picture recognition under normal conditions than artificial intelligence does. However, conditions of interference significantly reduce this capacity for picture recognition for instance, fatigue impairs human eyesight. Hence, psychological and physiological factors can affect the result when the human eye is adopted to measure MRTD (minimum resolvable temperature difference) and MRCTD (minimum resolvable circle temperature difference). This study explores thermal imaging recognition, and presents a method for effectively choosing the characteristic values and processing the images fully. Neural network technology is successfully applied to recognize thermal imaging and predict MRTD and MRCTD (Appendix A), exceeding thermal imaging recognition under fatigue and the limits of the human eye. PMID:18988953

Fang, Yi-Chin; Wu, Bo-Wen

2008-12-01

389

2D-to-3D Photo Rendering for 3D Displays Dario Comanducci  

E-print Network

fast and effective ap- proach to 2D-3D conversion of an image pair for the three- dimensional rendering2D-to-3D Photo Rendering for 3D Displays Dario Comanducci Dip. di Sistemi e Informatica, Univ. di geometry, and an original algorithm for the recovery of 3D visual param- eters from the properties

Martin, Ralph R.

390

A "LEARN 2D, APPLY 3D" METHOD FOR 3D DECONVOLUTION MICROSCOPY. Ferreol Soulez  

E-print Network

structure marked by fluorescent dye excited by uniform illumination. On the resulting 2D image, struc- turesA "LEARN 2D, APPLY 3D" METHOD FOR 3D DECONVOLUTION MICROSCOPY. Ferr´eol Soulez Centre de Recherche at the "the 3D Deconvolution Microscopy Challenge" held during ISBI 2013. It uses sparse cod- ing algorithm

Paris-Sud XI, Université de

391

Vision Research 38 (1998) 25072519 2D observers for human 3D object recognition?  

E-print Network

the authors showed that all models with independent 2D templates that allowed 2D rotations in the image plane observer; Template matching 1. Introduction A basic component in three-dimensional (3D) object recognition is a process that matches the input stimulus to stored object representations in memory. The search for a match

Kersten, Dan

392