WorldWideScience

Sample records for two-dimensional gray image

  1. Two dimensional estimates from ocean SAR images

    Directory of Open Access Journals (Sweden)

    J. M. Le Caillec

    1996-01-01

    Full Text Available Synthetic Aperture Radar (SAR images of the ocean yield a lot of information on the sea-state surface providing that the mapping process between the surface and the image is clearly defined. However it is well known that SAR images exhibit non-gaussian statistics and that the motion of the scatterers on the surface, while the image is being formed, may yield to nonlinearities. The detection and quantification of these nonlinearities are made possible by using Higher Order Spectra (HOS methods and more specifically, bispectrum estimation. The development of the latter method allowed us to find phase relations between different parts of the image and to recognise their level of coupling, i.e. if and how waves of different wavelengths interacted nonlinearly. This information is quite important as the usual models assume strong nonlinearities when the waves are propagating in the azimuthal direction (i.e. along the satellite track and almost no nonlinearities when propagating in the range direction. In this paper, the mapping of the ocean surface to the SAR image is reinterpreted and a specific model (i.e. a Second Order Volterra Model is introduced. The nonlinearities are thus explained as either produced by a nonlinear system or due to waves propagating into selected directions (azimuth or range and interacting during image formation. It is shown that quadratic nonlinearities occur for waves propagating near the range direction while for those travelling in the azimuthal direction the nonlinearities, when present, are mostly due to wave interactions but are almost completely removed by the filtering effect coming from the surface motion itself (azimuth cut-off. An inherent quadratic interaction filtering (azimuth high pass filter is also present. But some other effects, apparently nonlinear, are not detected with the methods described here, meaning that either the usual relation developed for the Ocean-to-SAR transform is somewhat incomplete

  2. Two dimensional convolute integers for machine vision and image recognition

    Science.gov (United States)

    Edwards, Thomas R.

    1988-01-01

    Machine vision and image recognition require sophisticated image processing prior to the application of Artificial Intelligence. Two Dimensional Convolute Integer Technology is an innovative mathematical approach for addressing machine vision and image recognition. This new technology generates a family of digital operators for addressing optical images and related two dimensional data sets. The operators are regression generated, integer valued, zero phase shifting, convoluting, frequency sensitive, two dimensional low pass, high pass and band pass filters that are mathematically equivalent to surface fitted partial derivatives. These operators are applied non-recursively either as classical convolutions (replacement point values), interstitial point generators (bandwidth broadening or resolution enhancement), or as missing value calculators (compensation for dead array element values). These operators show frequency sensitive feature selection scale invariant properties. Such tasks as boundary/edge enhancement and noise or small size pixel disturbance removal can readily be accomplished. For feature selection tight band pass operators are essential. Results from test cases are given.

  3. New two-dimensional fuzzy C-means clustering algorithm for image segmentation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To solve the problem of poor anti-noise performance of the traditional fuzzy C-means (FCM) algorithm in image segmentation,a novel two-dimensional FCM clustering algorithm for image segmentation was proposed.In this method,the image segmentation was converted into an optimization problem.The fitness function containing neighbor information was set up based on the gray information and the neighbor relations between the pixcls described by the improved two-dimensional histogram.By making use of the global searching ability of the predator-prey particle swarm optimization,the optimal cluster center could be obtained by iterative optimization,and the image segmentation could be accomplished.The simulation results show that the segmentation accuracy ratio of the proposed method is above 99%.The proposed algorithm has strong anti-noise capability,high clustering accuracy and good segment effect,indicating that it is an effective algorithm for image segmentation.

  4. Analysis of Two-Dimensional Electrophoresis Gel Images

    DEFF Research Database (Denmark)

    Pedersen, Lars

    2002-01-01

    This thesis describes and proposes solutions to some of the currently most important problems in pattern recognition and image analysis of two-dimensional gel electrophoresis (2DGE) images. 2DGE is the leading technique to separate individual proteins in biological samples with many biological...... the methods developed in the literature specifically for matching protein spot patterns, the focus is on a method based on neighbourhood relations. These methods are applied to a range of 2DGE protein spot data in a comparative study. The point pattern matching requires segmentation of the gel images...... and since the correct image segmentation can be difficult, a new alternative approach, exploiting prior knowledge from a reference gel about the protein locations to segment an incoming gel image, is proposed....

  5. Two-dimensional random arrays for real time volumetric imaging

    DEFF Research Database (Denmark)

    Davidsen, Richard E.; Jensen, Jørgen Arendt; Smith, Stephen W.

    1994-01-01

    Two-dimensional arrays are necessary for a variety of ultrasonic imaging techniques, including elevation focusing, 2-D phase aberration correction, and real time volumetric imaging. In order to reduce system cost and complexity, sparse 2-D arrays have been considered with element geometries...... real time volumetric imaging system, which employs a wide transmit beam and receive mode parallel processing to increase image frame rate. Depth-of-field comparisons were made from simulated on-axis and off-axis beamplots at ranges from 30 to 160 mm for both coaxial and offset transmit and receive...... selected ad hoc, by algorithm, or by random process. Two random sparse array geometries and a sparse array with a Mills cross receive pattern were simulated and compared to a fully sampled aperture with the same overall dimensions. The sparse arrays were designed to the constraints of the Duke University...

  6. Two-dimensional fruit ripeness estimation using thermal imaging

    Science.gov (United States)

    Sumriddetchkajorn, Sarun; Intaravanne, Yuttana

    2013-06-01

    Some green fruits do not change their color from green to yellow when being ripe. As a result, ripeness estimation via color and fluorescent analytical approaches cannot be applied. In this article, we propose and show for the first time how a thermal imaging camera can be used to two-dimensionally classify fruits into different ripeness levels. Our key idea relies on the fact that the mature fruits have higher heat capacity than the immature ones and therefore the change in surface temperature overtime is slower. Our experimental proof of concept using a thermal imaging camera shows a promising result in non-destructively identifying three different ripeness levels of mangoes Mangifera indica L.

  7. Two-dimensional Imaging Velocity Interferometry: Technique and Data Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J; Smith, R F; Bolme, C; Celliers, P; Collins, G

    2011-03-23

    We describe the data analysis procedures for an emerging interferometric technique for measuring motion across a two-dimensional image at a moment in time, i.e. a snapshot 2d-VISAR. Velocity interferometers (VISAR) measuring target motion to high precision have been an important diagnostic in shockwave physics for many years Until recently, this diagnostic has been limited to measuring motion at points or lines across a target. We introduce an emerging interferometric technique for measuring motion across a two-dimensional image, which could be called a snapshot 2d-VISAR. If a sufficiently fast movie camera technology existed, it could be placed behind a traditional VISAR optical system and record a 2d image vs time. But since that technology is not yet available, we use a CCD detector to record a single 2d image, with the pulsed nature of the illumination providing the time resolution. Consequently, since we are using pulsed illumination having a coherence length shorter than the VISAR interferometer delay ({approx}0.1 ns), we must use the white light velocimetry configuration to produce fringes with significant visibility. In this scheme, two interferometers (illuminating, detecting) having nearly identical delays are used in series, with one before the target and one after. This produces fringes with at most 50% visibility, but otherwise has the same fringe shift per target motion of a traditional VISAR. The 2d-VISAR observes a new world of information about shock behavior not readily accessible by traditional point or 1d-VISARS, simultaneously providing both a velocity map and an 'ordinary' snapshot photograph of the target. The 2d-VISAR has been used to observe nonuniformities in NIF related targets (polycrystalline diamond, Be), and in Si and Al.

  8. Image encryption using the two-dimensional logistic chaotic map

    Science.gov (United States)

    Wu, Yue; Yang, Gelan; Jin, Huixia; Noonan, Joseph P.

    2012-01-01

    Chaos maps and chaotic systems have been proved to be useful and effective for cryptography. In our study, the two-dimensional logistic map with complicated basin structures and attractors are first used for image encryption. The proposed method adopts the classic framework of the permutation-substitution network in cryptography and thus ensures both confusion and diffusion properties for a secure cipher. The proposed method is able to encrypt an intelligible image into a random-like one from the statistical point of view and the human visual system point of view. Extensive simulation results using test images from the USC-SIPI image database demonstrate the effectiveness and robustness of the proposed method. Security analysis results of using both the conventional and the most recent tests show that the encryption quality of the proposed method reaches or excels the current state-of-the-art methods. Similar encryption ideas can be applied to digital data in other formats (e.g., digital audio and video). We also publish the cipher MATLAB open-source-code under the web page https://sites.google.com/site/tuftsyuewu/source-code.

  9. Image interpolation by two-dimensional parametric cubic convolution.

    Science.gov (United States)

    Shi, Jiazheng; Reichenbach, Stephen E

    2006-07-01

    Cubic convolution is a popular method for image interpolation. Traditionally, the piecewise-cubic kernel has been derived in one dimension with one parameter and applied to two-dimensional (2-D) images in a separable fashion. However, images typically are statistically nonseparable, which motivates this investigation of nonseparable cubic convolution. This paper derives two new nonseparable, 2-D cubic-convolution kernels. The first kernel, with three parameters (designated 2D-3PCC), is the most general 2-D, piecewise-cubic interpolator defined on [-2, 2] x [-2, 2] with constraints for biaxial symmetry, diagonal (or 90 degrees rotational) symmetry, continuity, and smoothness. The second kernel, with five parameters (designated 2D-5PCC), relaxes the constraint of diagonal symmetry, based on the observation that many images have rotationally asymmetric statistical properties. This paper also develops a closed-form solution for determining the optimal parameter values for parametric cubic-convolution kernels with respect to ensembles of scenes characterized by autocorrelation (or power spectrum). This solution establishes a practical foundation for adaptive interpolation based on local autocorrelation estimates. Quantitative fidelity analyses and visual experiments indicate that these new methods can outperform several popular interpolation methods. An analysis of the error budgets for reconstruction error associated with blurring and aliasing illustrates that the methods improve interpolation fidelity for images with aliased components. For images with little or no aliasing, the methods yield results similar to other popular methods. Both 2D-3PCC and 2D-5PCC are low-order polynomials with small spatial support and so are easy to implement and efficient to apply.

  10. Subsurface imaging of two-dimensional materials at the nanoscale

    Science.gov (United States)

    Dinelli, Franco; Pingue, Pasqualantonio; Kay, Nicholas D.; Kolosov, Oleg V.

    2017-02-01

    Scanning probe microscopy (SPM) represents a powerful tool that, in the past 30 years, has allowed for the investigation of material surfaces in unprecedented ways at the nanoscale level. However, SPM has shown very little capability for depth penetration, which several nanotechnology applications require. Subsurface imaging has been achieved only in a few cases, when subsurface features influence the physical properties of the surface, such as the electronic states or the heat transfer. Ultrasonic force microscopy (UFM), an adaption of the contact mode atomic force microscopy, can dynamically measure the stiffness of the elastic contact between the probing tip and the sample surface. In particular, UFM has proven highly sensitive to the near-surface elastic field in non-homogeneous samples. In this paper, we present an investigation of two-dimensional (2D) materials, namely flakes of graphite and molybdenum disulphide placed on structured polymeric substrates. We show that UFM can non-destructively distinguish suspended and supported areas and localise defects, such as buckling or delamination of adjacent monolayers, generated by residual stress. Specifically, UFM can probe small variations in the local indentation induced by the mechanical interaction between the tip and the sample. Therefore, any change in the elastic modulus within the volume perturbed by the applied load or the flexural bending of the suspended areas can be detected and imaged. These investigation capabilities are very promising in order to study the buried interfaces of nanostructured 2D materials such as in graphene-based devices.

  11. Mathematical modeling of the neuron morphology using two dimensional images.

    Science.gov (United States)

    Rajković, Katarina; Marić, Dušica L; Milošević, Nebojša T; Jeremic, Sanja; Arsenijević, Valentina Arsić; Rajković, Nemanja

    2016-02-01

    In this study mathematical analyses such as the analysis of area and length, fractal analysis and modified Sholl analysis were applied on two dimensional (2D) images of neurons from adult human dentate nucleus (DN). Using mathematical analyses main morphological properties were obtained including the size of neuron and soma, the length of all dendrites, the density of dendritic arborization, the position of the maximum density and the irregularity of dendrites. Response surface methodology (RSM) was used for modeling the size of neurons and the length of all dendrites. However, the RSM model based on the second-order polynomial equation was only possible to apply to correlate changes in the size of the neuron with other properties of its morphology. Modeling data provided evidence that the size of DN neurons statistically depended on the size of the soma, the density of dendritic arborization and the irregularity of dendrites. The low value of mean relative percent deviation (MRPD) between the experimental data and the predicted neuron size obtained by RSM model showed that model was suitable for modeling the size of DN neurons. Therefore, RSM can be generally used for modeling neuron size from 2D images.

  12. Results from laboratory tests of the two-dimensional Time-Encoded Imaging System.

    Energy Technology Data Exchange (ETDEWEB)

    Marleau, Peter; Brennan, James S.; Brubaker, Erik; Gerling, Mark D; Le Galloudec, Nathalie Joelle

    2014-09-01

    A series of laboratory experiments were undertaken to demonstrate the feasibility of two dimensional time-encoded imaging. A prototype two-dimensional time encoded imaging system was designed and constructed. Results from imaging measurements of single and multiple point sources as well as extended source distributions are presented. Time encoded imaging has proven to be a simple method for achieving high resolution two-dimensional imaging with potential to be used in future arms control and treaty verification applications.

  13. Wavelet-based gray-level digital image watermarking

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The watermarking technique has been proposed as a method by hiding secret information into the im age to protect the copyright of multimedia data. But most previous work focuses on the algorithms of embedding one-dimensional watermarks or two-dimensional binary digital watermarks. In this paper, a wavelet-based method for embedding a gray-level digital watermark into an image is proposed. By still image decomposition technique, a gray-level digital watermark is decompounded into a series of bitplanes. By discrete wavelet transform ( DWT ), the host image is decomposed into multiresolution representations with hierarchical structure. Thedifferent bitplanes of the gray-level watermark is embedded into the corresponding resolution of the decomposed host image. The experimental results show that the proposed techniques can successfully survive image processing operations and the lossy compression techniques such as Joint Photographic Experts Group (JPEG).

  14. Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

    Institute of Scientific and Technical Information of China (English)

    鄢秋荣; 赵宝升; 刘永安; 杨颢; 盛立志; 韦永林

    2011-01-01

    A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensional Vernier anode are introduced in detail. A photon counting imaging system was built based on a

  15. Restoration of Scanning Tunneling Microscope Images by means of Two-Dimensional Maximum Entropy Method

    Science.gov (United States)

    Matsumoto, Hisanori; Tokiwano, Kazuo; Hosoi, Hirotaka; Sueoka, Kazuhisa; Mukasa, Koichi

    2002-05-01

    We present a new technique for the restoration of scanning tunneling microscopy (STM) images, which is a two-dimensional extension of a recently developed statistical approach based on the one-dimensional least-squares method (LSM). An STM image is regarded as a realization of a stochastic process and assumed to be a composition of an underlying image and noise. We express the underlying image in terms of a two-dimensional generalized trigonometric polynomial suitable for representing the atomic protrusions in STM images. The optimization of the polynomial is performed by the two-dimensional LSM combined with the power spectral density function estimated by means of the maximum entropy method (MEM) iterative algorithm for two-dimensional signals. The restored images are obtained as the optimum least-squares fitting polynomial which is a continuous surface. We apply this technique to modeled and actual STM data. Results show that the present method yields a reasonable restoration of STM images.

  16. Method and system for determining a volume of an object from two-dimensional images

    Science.gov (United States)

    Abercrombie, Robert K [Knoxville, TN; Schlicher, Bob G [Portsmouth, NH

    2010-08-10

    The invention provides a method and a computer program stored in a tangible medium for automatically determining a volume of three-dimensional objects represented in two-dimensional images, by acquiring at two least two-dimensional digitized images, by analyzing the two-dimensional images to identify reference points and geometric patterns, by determining distances between the reference points and the component objects utilizing reference data provided for the three-dimensional object, and by calculating a volume for the three-dimensional object.

  17. IMAGE ENCRYPTION ALGORITHM USING TWO-DIMENSIONAL CHAOTIC MAPS

    Directory of Open Access Journals (Sweden)

    A. V. Sidorenko

    2016-01-01

    Full Text Available A new image encryption algorithm based on dynamic chaos is proposed. The encryption is performed using the modified element permutation procedure. The element value changing procedure is carried with regard to the performed permutation. The modified permutation procedure includes the following steps: (1 permutation table creation; (2 permutation of image blocks, (3 element permutation in the image regions. The procedure «block permutations – permutation in the image regions» is performed q times – for this study q = 3. The second element value changing procedure is realized with the use of the pseudorandom sequence G that is added to the image elements. The following algorithm is proposed for the formation of this pseudorandom sequence: (1 the formation of the sequence G element distribution by brightness; (2 sequence G element initialization; (3 permutation of the sequence G elements. It is shown that, owing to the modified permutation procedure, the amount of calculations for new positions of the elements using chaotic maps is reduced by a factor of a – in this study a is equal to 16 and 64. The implementation of the proposed element value changing procedure necessitates the formation of d pseudorandom values from the interval [0, 1 with a uniform distribution. Actually, for the majority of practical cases d = 256 is applicable. The proposed algorithm has been tested as follows. The correlation coefficients have been computed for the original and encrypted images, and also for the adjacent elements in the vertical, horizontal, diagonal directions. The algorithm key sensitivity has been evaluated. Besides, the values of the unified average change intensity (UACI and the ratios of differing bits to the total number of bits have been determined. As demonstrated by the testing results, the proposed algorithm is highly operable and may be successfully used to solve the tasks of information security.

  18. Ultrasonic two-dimensional imaging of the heart with multiscan

    NARCIS (Netherlands)

    J.R.T.C. Roelandt (Jos)

    1980-01-01

    textabstractThe introduction of the prototype of an ultrasonic linear array scanner in 1971, confronted us with a type of diagnostic information which was different from conventional cardiac imaging techniques. With the use of ultrasound, cardiac structures were now displayed in a direct and positiv

  19. Real-time two-dimensional imaging of microbubble cavitation

    Science.gov (United States)

    Vignon, Francois; Shi, W. T.; Powers, J. E.; Liu, J.; Drvol, L.; Lof, J.; Everbach, C.; Gao, S.; Xie, F.; Porter, T.

    2012-10-01

    Ultrasound cavitation of microbubble contrast agents has a potential for therapeutic applications, including sonothrombolysis in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (e.g. stable versus inertial forms of cavitation) and intensity in and around a treatment area. Acoustic Passive Cavitation Detectors (PCDs) have been used but do not provide spatial information. This paper presents a prototype of a 2D cavitation imager capable of producing images of the dominant cavitation state and intensity in a region of interest at a frame rate of 0.6Hz. The system is based on a modified ultrasound scanner (iE33, Philips) with a sector imaging probe (S5-1). Cavitation imaging is based on the spectral analysis of the acoustic signal radiated by the cavitating microbubbles: ultraharmonics of the excitation frequency indicate stable cavitation, while noise bands indicate inertial cavitation. The system demonstrates the capability to robustly identify stable and inertial cavitation thresholds of Definity microbubbles (Lantheus) in a vessel phantom through 3 ex-vivo human temporal bones, as well as to spatially map cavitation activities.

  20. Optical imaging process based on two-dimensional Fourier transform for synthetic aperture imaging ladar

    Science.gov (United States)

    Sun, Zhiwei; Zhi, Ya'nan; Liu, Liren; Sun, Jianfeng; Zhou, Yu; Hou, Peipei

    2013-09-01

    The synthetic aperture imaging ladar (SAIL) systems typically generate large amounts of data difficult to compress with digital method. This paper presents an optical SAIL processor based on compensation of quadratic phase of echo in azimuth direction and two dimensional Fourier transform. The optical processor mainly consists of one phase-only liquid crystal spatial modulator(LCSLM) to load the phase data of target echo and one cylindrical lens to compensate the quadratic phase and one spherical lens to fulfill the task of two dimensional Fourier transform. We show the imaging processing result of practical target echo obtained by a synthetic aperture imaging ladar demonstrator. The optical processor is compact and lightweight and could provide inherent parallel and the speed-of-light computing capability, it has a promising application future especially in onboard and satellite borne SAIL systems.

  1. Simulation of laser bistatic two-dimensional scattering imaging about lambertian cylinders

    Science.gov (United States)

    Gong, Yanjun; Li, Lang; Wang, Mingjun; Gong, Lei

    2016-10-01

    This paper deals with the simulation of laser bi-static scattering imaging about lambertian cylinders. Two-dimensional imaging of a target can reflect the shape of the target and material property on the surface of the target. Two-dimensional imaging has important significance for target recognition. Simulations results of laser bi-static two-dimensional scattering imaging of some cylinders are given. The laser bi-static scattering imaging of cylinder, whose surface material with diffuse lambertian reflectance, is given in this paper. The scattering direction of laser bi-static scattering imaging is arbitrary direction. The scattering direction of backward two-dimensional scattering imaging is at opposite direction of the incident direction of laser. The backward two-dimensional scattering imaging is special case of bi-static two dimensional scattering imaging. The scattering intensity of a micro-element on the target could be obtained based on the laser radar equation. The intensity is related to local angle of incidence, local angle of scattering and the infinitesimal area on the surface of cylinder. According to the incident direction of incident laser and normal of infinitesimal area, the local incidence angle can be calculated. According to the scattering direction and normal of infinitesimal area, the local angle of scattering can be calculated. Through surface integration and the introduction of the rectangular function, we can get the intensity of imaging unit on the imaging surface, and then get mathematical model of bi-static laser two dimensional scattering imaging about lambert cylinder. From the results given, one can see that the simulation results of laser bi-static scattering about lambert cylinder is correct.

  2. VARIATION METHOD FOR ACOUSTIC WAVE IMAGING OF TWO DIMENSIONAL TARGETS

    Institute of Scientific and Technical Information of China (English)

    冯文杰; 邹振祝

    2003-01-01

    A new way of acoustic wave imaging was investigated. By using the Green function theory a system of integral equations, which linked wave number perturbation function with wave field, was firstly deduced. By taking variation on these integral equations an inversion equation, which reflected the relation between the little variation of wave number perturbation function and that of scattering field, was further obtained. Finally, the perturbation functions of some identical targets were reconstructed, and some properties of the novel method including converging speed, inversion accuracy and the abilities to resist random noise and identify complex targets were discussed. Results of numerical simulation show that the method based on the variation principle has great theoretical and applicable value to quantitative nondestructive evaluation.

  3. Two-dimensional pixel array image sensor for protein crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Beuville, E.; Beche, J.-F.; Cork, C. [and others

    1996-07-01

    A 2D pixel array image sensor module has been designed for time resolved Protein Crystallography. This smart pixels detector significantly enhances time resolved Laue Protein crystallography by two to three orders of magnitude compared to existing sensors like films or phosphor screens coupled to CCDs. The resolution in time and dynamic range of this type of detector will allow one to study the evolution of structural changes that occur within the protein as a function of time. This detector will also considerably accelerate data collection in static Laue or monochromatic crystallography and make better use of the intense beam delivered by synchrotron light sources. The event driven pixel array detectors, based on the column Architecture, can provide multiparameter information (energy discrimination, time), with sparse and frameless readout without significant dead time. The prototype module consists of a 16x16 pixel diode array bump-bonded to the integrated circuit. The detection area is 150x150 square microns.

  4. Two-dimensional Talbot self-imaging via Electromagnetically induced lattice

    Science.gov (United States)

    Wen, Feng; Wang, Wei; Ahmed, Irfan; Wang, Hongxing; Zhang, Yiqi; Zhang, Yanpeng; Mahesar, Abdul Rasheed; Xiao, Min

    2017-02-01

    We propose a lensless optical method for imaging two-dimensional ultra-cold atoms (or molecules) in which the image can be non-locally observed by coincidence recording of entangled photon pairs. In particular, we focus on the transverse and longitudinal resolutions of images under various scanning methods. In addition, the role of the induced nonmaterial lattice on the image contrast is investigated. Our work shows a non-destructive and lensless way to image ultra-cold atoms or molecules that can be further used for two-dimensional atomic super-resolution optical testing and sub-wavelength lithography.

  5. Volumetric and two-dimensional image interpretation show different cognitive processes in learners

    NARCIS (Netherlands)

    van der Gijp, Anouk; Ravesloot, C.J.; van der Schaaf, Marieke F; van der Schaaf, Irene C; Huige, Josephine C B M; Vincken, Koen L; Ten Cate, Olle Th J; van Schaik, JPJ

    2015-01-01

    RATIONALE AND OBJECTIVES: In current practice, radiologists interpret digital images, including a substantial amount of volumetric images. We hypothesized that interpretation of a stack of a volumetric data set demands different skills than interpretation of two-dimensional (2D) cross-sectional imag

  6. SAR IMAGING SIMULATION OF HORIZONTAL FULLY TWO-DIMENSIONAL INTERNAL WAVES

    Institute of Scientific and Technical Information of China (English)

    SHEN Hui; HE Yi-Jun

    2006-01-01

    Based on the research of Lynett and Liu, a new horizontal fully two-dimensional internal wave propagation model with rotation effect was deduced, which can be used to simulate the characteristics of internal waves in a horizontal fully two-dimensional plane. By combining the imaging mechanism of Synthetic Aperture Radar(SAR), a simulation procedure was fatherly acquired, which can simulate the propagation characteristics of oceanic internal waves into SAR images. In order to evaluate the validity of the proposed simulation procedure, case studies are performed in South China Sea and results from simulation procedure are analyzed in detail. A very good consistency was found between the simulation results and satellite images. The proposed simulation procedure will be a possible foundation for the quantitative interpretation of internal waves from fully two-dimensional satellite images.

  7. Laser bistatic two-dimensional scattering imaging simulation of lambert cone

    Science.gov (United States)

    Gong, Yanjun; Zhu, Chongyue; Wang, Mingjun; Gong, Lei

    2015-11-01

    This paper deals with the laser bistatic two-dimensional scattering imaging simulation of lambert cone. Two-dimensional imaging is called as planar imaging. It can reflect the shape of the target and material properties. Two-dimensional imaging has important significance for target recognition. The expression of bistatic laser scattering intensity of lambert cone is obtained based on laser radar eauqtion. The scattering intensity of a micro-element on the target could be obtained. The intensity is related to local angle of incidence, local angle of scattering and the infinitesimal area on the cone. According to the incident direction of laser, scattering direction and normal of infinitesimal area, the local incidence angle and scattering angle can be calculated. Through surface integration and the introduction of the rectangular function, we can get the intensity of imaging unit on the imaging surface, and then get Lambert cone bistatic laser two-dimensional scattering imaging simulation model. We analyze the effect of distinguishability, incident direction, observed direction and target size on the imaging. From the results, we can see that the scattering imaging simulation results of the lambert cone bistatic laser is correct.

  8. Imaging hemodynamic changes in preterm infant brains with two-dimensional diffuse optical tomography

    Science.gov (United States)

    Gao, Feng; Ma, Yiwen; Yang, Fang; Zhao, Huijuan; Jiang, Jingying; Kusaka, Takashi; Ueno, Masanori; Yamada, Yukio

    2008-02-01

    We present our preliminary results on two-dimensional (2-D) optical tomographic imaging of hemodynamic changes of two preterm infant brains in different ventilation settings conditions. The investigations use the established two-wavelength, 16-channel time-correlated single photon counting system for the detection, and the generalized pulse spectrum technique based algorithm for the image reconstruction. The experiments demonstrate that two-dimensional diffuse optical tomography may be a potent and relatively simple way of investigating the functions and neural development of infant brains in the perinatal period.

  9. Underwater sonar image recognition based on gray-spatial histograms

    Institute of Scientific and Technical Information of China (English)

    LIU Zhuo-fu; SANG En-fang

    2003-01-01

    A new gray-spatial histogram is proposed, which incorporates spatial information with gray compositions without sacrificing the robustness of traditional gray histograms. The purpose is to consider the representation role of gray compositions and spatial information simultaneously. Each entry in the gray-spatial histogram is the gray frequency and corresponding position information of images. In the experiments of sonar image recognition, the results show that the gray-spatial histogram is effective in practical use.

  10. Two-dimensional imaging of optical emission in a multicusp-ECR microwave resonant cavity

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, C.B.; Brake, M.L. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering

    1996-02-01

    Optical emission of the electron-cyclotron resonant (ECR) region of a multicusp microwave resonant cavity plasma source has been imaged onto a two-dimensional charge-coupled device (CCD) camera. The technique provides a real-time diagnostic of the plasma emission around the ECR region within a wavelength region defined by low-bandpass filters.

  11. Scale Adjustments to Facilitate Two-Dimensional Measurements in OCT Images.

    Directory of Open Access Journals (Sweden)

    Marina Garcia Garrido

    Full Text Available To address the problem of unequal scales for the measurement of two-dimensional structures in OCT images, and demonstrate the use of intra¬ocular objects of known dimensions in the murine eye for the equal calibration of axes.The first part of this work describes the mathematical foundation of major distortion effects introduced by X-Y scaling differences. Illustrations were generated with CorelGraph X3 software. The second part bases on image data obtained with a HRA2 Spectralis (Heidelberg Engineering in SV129 wild-type mice. Subretinally and intravitreally implanted microbeads, alginate capsules with a diameter of 154±5 μm containing GFP-marked mesenchymal stem cells (CellBeads, were used as intraocular objects for calibration.The problems encountered with two-dimensional measurements in cases of unequal scales are demonstrated and an estimation of the resulting errors is provided. Commonly, the Y axis is reliably calibrated using outside standards like histology or manufacturer data. We show here that intraocular objects like dimensionally stable spherical alginate capsules allow for a two-dimensional calibration of the acquired OCT raw images by establishing a relation between X and Y axis data. For our setup, a correction factor of about 3.3 was determined using both epiretinally and subretinally positioned beads (3.350 ± 0.104 and 3.324 ± 0.083, respectively.In this work, we highlight the distortion-related problems in OCT image analysis induced by unequal X and Y scales. As an exemplary case, we provide data for a two-dimensional in vivo OCT image calibration in mice using intraocular alginate capsules. Our results demonstrate the need for a proper two-dimensional calibration of OCT data, and we believe that equal scaling will certainly improve the efficiency of OCT image analysis.

  12. Discriminating image textures with the multiscale two-dimensional complexity-entropy causality plane

    CERN Document Server

    Zunino, Luciano

    2016-01-01

    The aim of this paper is to further explore the usefulness of the two-dimensional complexity-entropy causality plane as a texture image descriptor. A multiscale generalization is introduced in order to distinguish between different roughness features of images at small and large spatial scales. Numerically generated two-dimensional structures are initially considered for illustrating basic concepts in a controlled framework. Then, more realistic situations are studied. Obtained results allow us to confirm that intrinsic spatial correlations of images are successfully unveiled by implementing this multiscale symbolic information-theory approach. Consequently, we conclude that the proposed representation space is a versatile and practical tool for identifying, characterizing and discriminating image textures.

  13. Silicon strip detectors for two-dimensional soft X-ray imaging at normal incidence

    Energy Technology Data Exchange (ETDEWEB)

    Rato Mendes, P. E-mail: rato@lip.pt; Abreu, M.C.; Baldazzi, G.; Bollini, D.; Cabal Rodriguez, A.E.; Dabrowski, W.; Diaz Garcia, A.; Gambaccini, M.; Giubellino, P.; Gombia, M.; Grybos, P.; Idzik, M.; Marzari-Chiesa, A.; Montano, L.M.; Prino, F.; Ramello, L.; Rodrigues, S.; Sitta, M.; Sousa, P.; Swientek, K.; Taibi, A.; Tuffanelli, A.; Wheadon, R.; Wiacek, P

    2003-08-21

    A simple prototype system for static two-dimensional soft X-ray imaging using silicon microstrip detectors irradiated at normal incidence is presented. Radiation sensors consist of single-sided silicon detectors made from 300 {mu}m thick wafers, read by RX64 ASICs. Data acquisition and control is performed by a Windows PC workstation running dedicated LabVIEW routines, connected to the sensors through a PCI-DIO-96 interface. Two-dimensional images are obtained by scanning a lead collimator with a thin slit perpendicular to the strip axis, along the whole detector size; the several strip profiles (slices) taken at each position are then put together to form a planar image. Preliminary results are presented, illustrating the high-resolution imaging capabilities of the system with soft X-rays.

  14. Infrared image gray adaptive adjusting enhancement algorithm based on gray redundancy histogram-dealing technique

    Science.gov (United States)

    Hao, Zi-long; Liu, Yong; Chen, Ruo-wang

    2016-11-01

    In view of the histogram equalizing algorithm to enhance image in digital image processing, an Infrared Image Gray adaptive adjusting Enhancement Algorithm Based on Gray Redundancy Histogram-dealing Technique is proposed. The algorithm is based on the determination of the entire image gray value, enhanced or lowered the image's overall gray value by increasing appropriate gray points, and then use gray-level redundancy HE method to compress the gray-scale of the image. The algorithm can enhance image detail information. Through MATLAB simulation, this paper compares the algorithm with the histogram equalization method and the algorithm based on gray redundancy histogram-dealing technique , and verifies the effectiveness of the algorithm.

  15. X-ray Phase Imaging Microscopy with Two-Dimensional Knife-Edge Filters

    Science.gov (United States)

    Choi, Jaeho; Park, Yong-Sung

    2012-04-01

    A novel scheme of X-ray differential phase imaging was implemented with an array source and a two-dimensional Foucault knife-edge (2DFK). A pinhole array lens was employed to manipulate the X-ray beam on the Fourier space. An emerging biaxial scanning procedure was also demonstrated with the periodic 2DFK. The differential phase images (DPIs) of the midrib in a leaf of a rose bush were visualized to verify the phase imaging of biological specimens by the proposed method. It also has features of depicting multiple-stack phase images, and rendering morphological DPIs, because it acquires pure phase information.

  16. New Approach for Segmentation and Quantification of Two-Dimensional Gel Electrophoresis Images

    DEFF Research Database (Denmark)

    Anjo, Antonio dos; Laurell Blom Møller, Anders; Ersbøll, Bjarne Kjær;

    2011-01-01

    Motivation: Detection of protein spots in two-dimensional gel electrophoresis images (2-DE) is a very complex task and current approaches addressing this problem still suffer from significant shortcomings. When quantifying a spot, most of the current software applications include a lot of backgro......Motivation: Detection of protein spots in two-dimensional gel electrophoresis images (2-DE) is a very complex task and current approaches addressing this problem still suffer from significant shortcomings. When quantifying a spot, most of the current software applications include a lot....... Results: Five sections from different gels are used to test the performance of the presented method concerning the detection of protein spots, and three gel sections are used to test the quantification of sixty protein spots. Comparisons with a state-of-the-art commercial software and an academic state...

  17. A MATLAB package for the EIDORS project to reconstruct two-dimensional EIT images.

    Science.gov (United States)

    Vauhkonen, M; Lionheart, W R; Heikkinen, L M; Vauhkonen, P J; Kaipio, J P

    2001-02-01

    The EIDORS (electrical impedance and diffuse optical reconstruction software) project aims to produce a software system for reconstructing images from electrical or diffuse optical data. MATLAB is a software that is used in the EIDORS project for rapid prototyping, graphical user interface construction and image display. We have written a MATLAB package (http://venda.uku.fi/ vauhkon/) which can be used for two-dimensional mesh generation, solving the forward problem and reconstructing and displaying the reconstructed images (resistivity or admittivity). In this paper we briefly describe the mathematical theory on which the codes are based on and also give some examples of the capabilities of the package.

  18. Two-dimensional Fibonacci grating for far-field super-resolution imaging

    Science.gov (United States)

    Wu, Kedi; Wang, Guo Ping

    2016-12-01

    A two-dimensional (2D) Fibonacci grating is used to transform evanescent waves into propagating waves for far-field super-resolution imaging. By detecting far-field intensity distributions of light field through objects in front of the 2D Fibonacci grating in free space at once, we can retrieve the image of objects with beyond λ/7 spatial resolution. We also find that the coherent illumination case can give a better resolution than incoherent illumination case by such 2D grating-assisted imaging system. The analytical results are verified by numerical simulation.

  19. Two dimensional density and its fluctuation measurements by using phase imaging method in GAMMA 10

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, M.; Negishi, S.; Shima, Y.; Hojo, H.; Imai, T. [Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Mase, A. [Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Kogi, Y. [Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashiku, Fukuoka 811-0295 (Japan)

    2010-10-15

    Two dimensional (2D) plasma image analysis is useful to study the improvement of plasma confinement in magnetically confined fusion plasmas. We have constructed a 2D interferometer system with phase imaging method for studying 2D plasma density distribution and its fluctuation measurement in the tandem mirror GAMMA 10. 2D profiles of electron density and its fluctuation have been successfully obtained by using this 2D phase imaging system. We show that 2D plasma density and fluctuation profiles clearly depends on the axial confining potential formation with application of plug electron cyclotron heating in GAMMA 10.

  20. X-ray tests of a two-dimensional stigmatic imaging scheme with variable magnifications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J., E-mail: jlu@pppl.gov [Key Laboratory of Optoelectronic Technology and System of Ministry of Education, Chongqing University, Chongqing 400030 (China); Bitter, M.; Hill, K. W.; Delgado-Aparicio, L. F.; Efthimion, P. C.; Pablant, N. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Beiersdorfer, P. [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Caughey, T. A.; Brunner, J. [Inrad Optics, 181 Legrand Avenue, Northvale, New Jersey 07647 (United States)

    2014-11-15

    A two-dimensional stigmatic x-ray imaging scheme, consisting of two spherically bent crystals, one concave and one convex, was recently proposed [M. Bitter et al., Rev. Sci. Instrum. 83, 10E527 (2012)]. The Bragg angles and the radii of curvature of the two crystals of this imaging scheme are matched to eliminate the astigmatism and to satisfy the Bragg condition across both crystal surfaces for a given x-ray energy. In this paper, we consider more general configurations of this imaging scheme, which allow us to vary the magnification for a given pair of crystals and x-ray energy. The stigmatic imaging scheme has been validated for the first time by imaging x-rays generated by a micro-focus x-ray source with source size of 8.4 μm validated by knife-edge measurements. Results are presented from imaging the tungsten Lα1 emission at 8.3976 keV, using a convex Si-422 crystal and a concave Si-533 crystal with 2d-spacings of 2.21707 Å and 1.65635 Å and radii of curvature of 500 ± 1 mm and 823 ± 1 mm, respectively, showing a spatial resolution of 54.9 μm. This imaging scheme is expected to be of interest for the two-dimensional imaging of laser produced plasmas.

  1. X-ray tests of a two-dimensional stigmatic imaging scheme with variable magnifications

    Science.gov (United States)

    Lu, J.; Bitter, M.; Hill, K. W.; Delgado-Aparicio, L. F.; Efthimion, P. C.; Pablant, N. A.; Beiersdorfer, P.; Caughey, T. A.; Brunner, J.

    2014-11-01

    A two-dimensional stigmatic x-ray imaging scheme, consisting of two spherically bent crystals, one concave and one convex, was recently proposed [M. Bitter et al., Rev. Sci. Instrum. 83, 10E527 (2012)]. The Bragg angles and the radii of curvature of the two crystals of this imaging scheme are matched to eliminate the astigmatism and to satisfy the Bragg condition across both crystal surfaces for a given x-ray energy. In this paper, we consider more general configurations of this imaging scheme, which allow us to vary the magnification for a given pair of crystals and x-ray energy. The stigmatic imaging scheme has been validated for the first time by imaging x-rays generated by a micro-focus x-ray source with source size of 8.4 μm validated by knife-edge measurements. Results are presented from imaging the tungsten Lα1 emission at 8.3976 keV, using a convex Si-422 crystal and a concave Si-533 crystal with 2d-spacings of 2.21707 Å and 1.65635 Å and radii of curvature of 500 ± 1 mm and 823 ± 1 mm, respectively, showing a spatial resolution of 54.9 μm. This imaging scheme is expected to be of interest for the two-dimensional imaging of laser produced plasmas.

  2. Two-dimensional maximum local variation based on image euclidean distance for face recognition.

    Science.gov (United States)

    Gao, Quanxue; Gao, Feifei; Zhang, Hailin; Hao, Xiu-Juan; Wang, Xiaogang

    2013-10-01

    Manifold learning concerns the local manifold structure of high dimensional data, and many related algorithms are developed to improve image classification performance. None of them, however, consider both the relationships among pixels in images and the geometrical properties of various images during learning the reduced space. In this paper, we propose a linear approach, called two-dimensional maximum local variation (2DMLV), for face recognition. In 2DMLV, we encode the relationships among pixels in images using the image Euclidean distance instead of conventional Euclidean distance in estimating the variation of values of images, and then incorporate the local variation, which characterizes the diversity of images and discriminating information, into the objective function of dimensionality reduction. Extensive experiments demonstrate the effectiveness of our approach.

  3. Two-dimensional sonographic cine imaging improves confidence in the initial evaluation of the fetal heart.

    Science.gov (United States)

    Poole, Patricia Sims; Chung, Romy; Lacoursiere, Yvette; Palmieri, Carolina Rossi; Hull, Andrew; Engelkemier, Dawn; Rochelle, Michele; Trivedi, Neha; Pretorius, Dolores H

    2013-06-01

    Initial screening sonography of the fetal heart with static images is often inadequate, resulting in repeated imaging or failure to detect abnormalities. We hypothesized that the addition of short cine clips would reduce the need for repeated imaging. Two-dimensional (2D) static sonograms and short 2D cine clips of the 4-chamber view and left and right ventricular outflow tracts were obtained from 342 patients with gestational ages of greater than 16 weeks. A diagnostic radiologist and a perinatologist retrospectively reviewed the static and cine images independently and graded them as normal, abnormal, or suboptimal. A statistically significant increase in the number of structures called normal was seen when 2D cine clips were added to static imaging for both observers (P cine images versus 61.9% with static images alone, whereas the perinatologist recorded 68.1% as normal versus 58.8%, respectively. The radiologist called 77.8% of structures normal with cine images only versus 61.9% with static images only (P cine images alone (38.9%) versus static images alone (58.8%). The use of cine loops alone resulted in no significant increase in the ability to clear the heart as normal. The maternal body mass index was inversely associated with the ability to clear structures when 2D cine images were added to static images (P cine clips to standard 2D static imaging of the fetal heart significantly improves the number of structures cleared as normal. Two-dimensional cine clips are easily obtained, add little time to a study, and require minimal archival space.

  4. APPLICATION OF TWO-DIMENSIONAL WAVELET TRANSFORM IN NEAR-SHORE X-BAND RADAR IMAGES

    Institute of Scientific and Technical Information of China (English)

    FENG Xiang-bo; YAN Yi-xin; ZHANG Wei

    2011-01-01

    Among existing remote sensing applications, land-based X-band radar is an effective technique to monitor the wave fields,and spatial wave information could be obtained from the radar images.Two-dimensional Fourier Transform (2-D FT) is the common algorithm to derive the spectra of radar images.However, the wave field in the nearshore area is highly non-homogeneous due to wave refraction, shoaling, and other coastal mechanisms.When applied in nearshore radar images, 2-D FT would lead to ambiguity of wave characteristics in wave number domain.In this article, we introduce two-dimensional Wavelet Transform (2-D WT) to capture the non-homogeneity of wave fields from nearshore radar images.The results show that wave number spectra by 2-D WT at six parallel space locations in the given image clearly present the shoaling of nearshore waves.Wave number of the peak wave energy is increasing along the inshore direction, and dominant direction of the spectra changes from South South West (SSW) to West South West (WSW).To verify the results of2-D WT, wave shoaling in radar images is calculated based on dispersion relation.The theoretical calculation results agree with the results of 2-D WT on the whole.The encouraging performance of 2-D WT indicates its strong capability of revealing the non-homogeneity of wave fields in nearshore X-band radar images.

  5. Two-dimensional electrophoresis analysis of proteomics based on image feature and mathematical morphology

    Institute of Scientific and Technical Information of China (English)

    SHEN Peng; FAN Xiaohui; ZENG Zhen; CHENG Yiyu

    2005-01-01

    In this paper, a novel method to automatically detect protein spots on a two-dimensional (2-D) electrophoresis gel image is proposed to implement proteomics analysis of complex analyte.On the basis of the identifying spots results based on color variation and spot size features, morphological feature is introduced as a new criterion to distinguish protein spots from non-protein spots.Image-sharpening, edge-detecting and morphological feature extraction methods were consequently combined to detect protein spots on a 2-D electrophoresis gel image subject to strong disturbance.The proposed method was applied to detect the protein spots of proteomic gel images from E.coli cell, human kidney tissue and human serum.The results demonstrated that this method is more accurate and reliable than previous methods such as PDQuest 7.2 and ImageMaster 5.0 software for detecting protein spots on gel images with strong interferences.

  6. Two-dimensional confocal laser scanning microscopy image correlation for nanoparticle flow velocimetry

    Science.gov (United States)

    Jun, Brian; Giarra, Matthew; Golz, Brian; Main, Russell; Vlachos, Pavlos

    2016-11-01

    We present a methodology to mitigate the major sources of error associated with two-dimensional confocal laser scanning microscopy (CLSM) images of nanoparticles flowing through a microfluidic channel. The correlation-based velocity measurements from CLSM images are subject to random error due to the Brownian motion of nanometer-sized tracer particles, and a bias error due to the formation of images by raster scanning. Here, we develop a novel ensemble phase correlation with dynamic optimal filter that maximizes the correlation strength, which diminishes the random error. In addition, we introduce an analytical model of CLSM measurement bias error correction due to two-dimensional image scanning of tracer particles. We tested our technique using both synthetic and experimental images of nanoparticles flowing through a microfluidic channel. We observed that our technique reduced the error by up to a factor of ten compared to ensemble standard cross correlation (SCC) for the images tested in the present work. Subsequently, we will assess our framework further, by interrogating nanoscale flow in the cell culture environment (transport within the lacunar-canalicular system) to demonstrate our ability to accurately resolve flow measurements in a biological system.

  7. Mathematical description of the two-dimensional Gabor transform. Application to image encryption

    Science.gov (United States)

    Perez, Ronal; Vilardy, Juan M.; Torres, Cesar O.

    2017-01-01

    Information security with optical processing, such as the double random phase encoding and the Gabor transform (GT) has been investigated by various researchers. We present a two-dimensional (2-D) generalization of the one-dimensional GT. This 2-D GT is applied to encrypt digital images in this paper. The scaling factors of the GT can be used as new keys, providing a new encryption system with a high security characteristics. This method can encrypt and protect the information of the digital images with a high security for information processing systems.

  8. Tunable far-field acoustic imaging by two-dimensional sonic crystal with concave incident surface

    Science.gov (United States)

    Shen, Feng-Fu; Lu, Dan-Feng; Zhu, Hong-Wei; Ji, Chang-Ying; Shi, Qing-Fan

    2017-01-01

    An additional concave incident surface comprised of two-dimensional (2D) sonic crystals (SCs) is employed to tune the acoustic image in the far-field region. The tunability is realized through changing the curvature of the concave surface. To explain the tuning mechanism, a simple ray-trace analysis is demonstrated based on the wave-beam negative refractive law. Then, a numerical confirmation is carried out. Results show that both the position and the intensity of the image can be tuned by the introduced concave surface.

  9. Observation of asymmetrically imploded core plasmas with a two-dimensional sampling image x-ray streak camera.

    Science.gov (United States)

    Shiraga, Hiroyuki; Lee, Myongdok; Mahigashi, Norimitsu; Fujioka, Shinsuke; Azechi, Hiroshi

    2008-10-01

    A shell target with a cone for guiding the heating beam has been proposed for the fast ignition scheme. Implosion of such target is no longer symmetric because of the cone. A fast two-dimensional x-ray imaging technique, two-dimensional (2D) sampling image x-ray streak camera was applied for the first time to observation of the dynamics of implosion and core plasma. X-ray emission image of the plasma was sampled with two-dimensionally distributed image sampling points, streaked with the tube, and the recorded signals were reconstructed as sequential 2D frame images. Shape and movement of the core plasma were clearly observed.

  10. Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

    Institute of Scientific and Technical Information of China (English)

    YAN Qiu-Rong; ZHAO Bao-Sheng; LIU Yong-An; YANG Hao; SHENG Li-Zhi; WEI Yong-Lin

    2011-01-01

    A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensionai Vernier anode axe introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of high- energy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.

  11. Two dimensional recursive digital filters for near real time image processing

    Science.gov (United States)

    Olson, D.; Sherrod, E.

    1980-01-01

    A program was designed toward the demonstration of the feasibility of using two dimensional recursive digital filters for subjective image processing applications that require rapid turn around. The concept of the use of a dedicated minicomputer for the processor for this application was demonstrated. The minicomputer used was the HP1000 series E with a RTE 2 disc operating system and 32K words of memory. A Grinnel 256 x 512 x 8 bit display system was used to display the images. Sample images were provided by NASA Goddard on a 800 BPI, 9 track tape. Four 512 x 512 images representing 4 spectral regions of the same scene were provided. These images were filtered with enhancement filters developed during this effort.

  12. Usefulness of two-dimensional and speckle tracking echocardiography in "Gray Zone" left ventricular hypertrophy to differentiate professional football player's heart from hypertrophic cardiomyopathy.

    Science.gov (United States)

    Kansal, Mayank M; Lester, Steven J; Surapaneni, Phani; Sengupta, Partho P; Appleton, Christopher P; Ommen, Steven R; Ressler, Steven W; Hurst, R Todd

    2011-11-01

    Distinguishing the pathologic hypertrophy of hypertrophic cardiomyopathy (HC) from the physiologic hypertrophy of professional football players (PFP) can be challenging when septal wall thickness falls within a "gray zone" between 12 and 16 mm. It was hypothesized that 2-dimensional and speckle-tracking strain (ε) echocardiography could differentiate the hearts of PFPs from those of patients with HC with similar wall thicknesses. Sixty-six subjects, including 28 professional American football players and 21 patients with HC, with septal wall thicknesses of 12 to 16 mm, along with 17 normal controls, were studied using 2-dimensional echocardiography. Echocardiographic parameters, including modified relative wall thickness (RWT; septal wall thickness + posterior wall thickness/left ventricular end-diastolic diameter) and early diastolic annular tissue velocity (e'), were measured. Two-dimensional ε was analyzed by speckle tracking to measure endocardial and epicardial longitudinal ε and circumferential ε and radial cardiac ε. Septal wall thickness was higher in patients with HC than in PFPs (14.7 ± 1.1 vs 12.9 ± 0.9 mm, respectively, p <0.001), while posterior wall thickness showed no difference. RWT was larger in patients with HC than in PFPs (0.68 ± 0.10 vs 0.48 ± 0.06, p <0.001). Longitudinal endocardial ε and radial cardiac ε were significantly higher in PFPs than in patients with HC, while circumferential endocardial ε was no different. RWT was the parameter that most accurately differentiated PFPs from patients with HC. An RWT cut point of 0.6 differentiated PFPs from patients with HC, with an area under the curve of 0.97. In conclusion, a 2-dimensional echocardiographic measure of RWT (septal wall + posterior wall thickness/left ventricular end-diastolic dimension) accurately differentiated PFPs' hearts from those of patients with HC when septal wall thickness was in the gray zone of 12 to 16 mm. Two-dimensional strain analysis identifies

  13. Challenge for spectroscopic tomography of biomembrane using imaging type two-dimensional Fourier spectroscopy

    Science.gov (United States)

    Qi, Wei; Ishimaru, Ichiro

    2010-02-01

    We propose an image-producing Fourier spectroscopic technology that enables two-dimensional spectroscopic images to be obtained within the focusing plane alone. This technology incorporates auto-correlational phase-shift interferometry that uses only object light generated by the bright points that optically make up the object. We are currently involved in studies of non-invasive technologies used to measure blood components such as glucose and lipids, which are measured for use in daily living. Previous studies have investigated non-invasive technologies that measure blood glucose levels by utilizing near-infrared light that permeates the skin well. It has been confirmed that subtle changes in the concentration of a glucose solution, a sample used to measure the glucose level, can be measured by analyzing the spectroscopic characteristics of near-infrared light; however, when applied to a biomembrane, technology such as this is incapable of precisely measuring the glucose level because light diffusion within the skin disturbs the measurement. Our proposed technology enables two-dimensional spectroscopy to a limited depth below the skin covered by the measurement. Specifically, our technology concentrates only on the vascular territory near the skin surface, which is only minimally affected by light diffusion, as discussed previously; the spectroscopic characteristics of this territory are obtained and the glucose level can be measured with good sensitivity. In this paper we propose an image-producing Fourier spectroscopy method that is used as the measuring technology in producing a three-dimensional spectroscopic image.

  14. Two-Dimensional Gel Electrophoresis Image Analysis via Dedicated Software Packages.

    Science.gov (United States)

    Maurer, Martin H

    2016-01-01

    Analyzing two-dimensional gel electrophoretic images is supported by a number of freely and commercially available software. Although the respective program is highly specific, all the programs follow certain standardized algorithms. General steps are: (1) detecting and separating individual spots, (2) subtracting background, (3) creating a reference gel and (4) matching the spots to the reference gel, (5) modifying the reference gel, (6) normalizing the gel measurements for comparison, (7) calibrating for isoelectric point and molecular weight markers, and moreover, (8) constructing a database containing the measurement results and (9) comparing data by statistical and bioinformatic methods.

  15. Image Reconstruction of Two-Dimensional Highly Scattering Inhomogeneous Medium Using MAP-Based Estimation

    Directory of Open Access Journals (Sweden)

    Hong Qi

    2015-01-01

    Full Text Available A maximum a posteriori (MAP estimation based on Bayesian framework is applied to image reconstruction of two-dimensional highly scattering inhomogeneous medium. The finite difference method (FDM and conjugate gradient (CG algorithm serve as the forward and inverse solving models, respectively. The generalized Gaussian Markov random field model (GGMRF is treated as the regularization, and finally the influence of the measurement errors and initial distributions is investigated. Through the test cases, the MAP estimate algorithm is demonstrated to greatly improve the reconstruction results of the optical coefficients.

  16. Two-dimensional Tissue Image Reconstruction Based on Magnetic Field Data

    Directory of Open Access Journals (Sweden)

    J. Dedkova

    2012-09-01

    Full Text Available This paper introduces new possibilities within two-dimensional reconstruction of internal conductivity distribution. In addition to the electric field inside the given object, the injected current causes a magnetic field which can be measured either outside the object by means of a Hall probe or inside the object through magnetic resonance imaging. The Magnetic Resonance method, together with Electrical impedance tomography (MREIT, is well known as a bio-imaging modality providing cross-sectional conductivity images with a good spatial resolution from the measurements of internal magnetic flux density produced by externally injected currents. A new algorithm for the conductivity reconstruction, which utilizes the internal current information with respect to corresponding boundary conditions and the external magnetic field, was developed. A series of computer simulations has been conducted to assess the performance of the proposed algorithm within the process of estimating electrical conductivity changes in the lungs, heart, and brain tissues captured in two-dimensional piecewise homogeneous chest and head models. The reconstructed conductivity distribution using the proposed method is compared with that using a conventional method based on Electrical Impedance Tomography (EIT. The acquired experience is discussed and the direction of further research is proposed.

  17. A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

    Directory of Open Access Journals (Sweden)

    Khoo Sze-Wei

    2016-09-01

    Full Text Available Among the full-field optical measurement methods, the Digital Image Correlation (DIC is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

  18. Two-dimensional, single-photoelectron drift detector for Cherenkov ring imaging

    Energy Technology Data Exchange (ETDEWEB)

    Barrelet, E.; Seguinot, J.; Urban, M.; Ypsilantis, T. (Ecole Polytechnique, 91 - Palaiseau (France)); Ekeloef, T. (European Organization for Nuclear Research, Geneva (Switzerland)); Lund-Jensen, B. (Uppsala Univ. (Sweden)); Tocqueville, J. (College de France, 75 - Paris)

    1982-09-15

    A detector capable of imaging single photoelectrons has been constructed and tested. UV photons (>=5.4 eV) are converted to electrons with high quantum efficiency by photoionization of a small admixture (approx. equal to 1 Torr) of an organic vapour TMAE in a predominantly methane drift and amplifying gas at atmospheric pressure. The produced photoelectrons drift in a uniform applied electric field to a picket fence of proportional wires where each electron is amplified, counted and timed. The two-dimensional source point of each photoelectron is uniquely determined by the hit wire address and the arrival time. The detector has been tested by measuring ionization electrons produced in the drift gas be relativistic charged particles. The limiting precision to which the electron source point can be determined has been measured to be 300 ..mu..m (r.m.s.) in the drift direction and 370 ..mu..m in the wire plane direction. Additional independent error sources due to electron diffusion in the drift gas have been measured to be proportional to the square root of the drift distance with a proportionality constant of 235 ..mu..m/cmsup(1/2) in both directions. Drift velocities of electrons in various predominantly methane gas mixtures have been measured as a function of the applied electric field. The utilization of such a two-dimensional single electron drift detector for Cherenkov ring imaging is presented with a discussion of the advantages and limitations of the drift method for imaging.

  19. Security analysis of image encryption based on two-dimensional chaotic maps and improved algorithm

    Institute of Scientific and Technical Information of China (English)

    Feng HUANG; Yong FENG

    2009-01-01

    The article proposes a new algorithm to improve the security of image encryption based on two-dimensional chaotic maps.Chaotic maps are often used in encrypting images.However,the encryption has periodic-ity,no diffusion,and at the same time,the real keys space of encryption are fewer than the theoretical keys space,which consequently results in potential security problems.Thus,this article puts forward several ways to solve the problems including adding diffusion mechanism,changing the design of keys and developing a composite encryption system.It designs an algorithm for the version B of the discretized baker map,which is one of the most prevalent chaotic maps,based on which a new image encryption is proposed to avoid the above problems.The simulation results show that the new encryption algorithm is valid and the result can be applied to other two-dimensional chaotic maps,such as the cat map.

  20. Development of novel rare earth doped fluoride and oxide scintillators for two-dimensional imaging

    Institute of Scientific and Technical Information of China (English)

    A. Yoshikawa; T. Iguchi; G. Boulon; M. Nikd; T. Yanagida; Y. Yokota; K. Kamada; N. Kawaguchi; K. Fukuda; A. Yamazaki; K. Watanabe; A. Uritani

    2011-01-01

    Two topics were focused.The first one was about the gamma-ray scintillator,pr3+:Lu3Al5O12 (LuAG).The second one was about neutron scintillator,Ce3+:6LiCaAlF6 and Eu2+:6LiCaAlF6 (6LiCAF).Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields.In both cases,the rare earth ions are playing the crucial role as emission centers.Pr3+ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce3+.Among several candidate hosts,LuAG showed the best performance.Bulk crystal growth,basic scintillation properties,two-dimensional gamma-ray imaging and positron emission mammography (PEM) application were demonstrated.Due to the international situation,the homeland security was compromized by illicit traffic of explosives,drugs,nuclear materials,etc.and the ways to its improvement became an important R&D topic.For this purpose the Ce and Eu doped LiCAF appeared competitive candidates.Especially,when substitution of 3He neutron detectors was considered,the discrimination ability of gamma-ray from alpha-ray was important.Bulk crystal growth,basic scintillation properties and two-dimensional neutron imaging were demonstrated.

  1. Two-Dimensional Hermite Filters Simplify the Description of High-Order Statistics of Natural Images.

    Science.gov (United States)

    Hu, Qin; Victor, Jonathan D

    2016-09-01

    Natural image statistics play a crucial role in shaping biological visual systems, understanding their function and design principles, and designing effective computer-vision algorithms. High-order statistics are critical for conveying local features, but they are challenging to study - largely because their number and variety is large. Here, via the use of two-dimensional Hermite (TDH) functions, we identify a covert symmetry in high-order statistics of natural images that simplifies this task. This emerges from the structure of TDH functions, which are an orthogonal set of functions that are organized into a hierarchy of ranks. Specifically, we find that the shape (skewness and kurtosis) of the distribution of filter coefficients depends only on the projection of the function onto a 1-dimensional subspace specific to each rank. The characterization of natural image statistics provided by TDH filter coefficients reflects both their phase and amplitude structure, and we suggest an intuitive interpretation for the special subspace within each rank.

  2. Volumetric and two-dimensional image interpretation show different cognitive processes in learners.

    Science.gov (United States)

    van der Gijp, Anouk; Ravesloot, Cécile J; van der Schaaf, Marieke F; van der Schaaf, Irene C; Huige, Josephine C B M; Vincken, Koen L; Ten Cate, Olle Th J; van Schaik, Jan P J

    2015-05-01

    In current practice, radiologists interpret digital images, including a substantial amount of volumetric images. We hypothesized that interpretation of a stack of a volumetric data set demands different skills than interpretation of two-dimensional (2D) cross-sectional images. This study aimed to investigate and compare knowledge and skills used for interpretation of volumetric versus 2D images. Twenty radiology clerks were asked to think out loud while reading four or five volumetric computed tomography (CT) images in stack mode and four or five 2D CT images. Cases were presented in a digital testing program allowing stack viewing of volumetric data sets and changing views and window settings. Thoughts verbalized by the participants were registered and coded by a framework of knowledge and skills concerning three components: perception, analysis, and synthesis. The components were subdivided into 16 discrete knowledge and skill elements. A within-subject analysis was performed to compare cognitive processes during volumetric image readings versus 2D cross-sectional image readings. Most utterances contained knowledge and skills concerning perception (46%). A smaller part involved synthesis (31%) and analysis (23%). More utterances regarded perception in volumetric image interpretation than in 2D image interpretation (Median 48% vs 35%; z = -3.9; P Cognitive processes in volumetric and 2D cross-sectional image interpretation differ substantially. Volumetric image interpretation draws predominantly on perceptual processes, whereas 2D image interpretation is mainly characterized by synthesis. The results encourage the use of volumetric images for teaching and testing perceptual skills. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  3. High resolution, two-dimensional imaging, microchannel plate detector for use on a sounding rocket experiment

    Science.gov (United States)

    Bush, Brett C.; Cotton, Daniel M.; Siegmund, Oswald H.; Chakrabarti, Supriya; Harris, Walter; Clarke, John

    1991-01-01

    We discuss a high resolution microchannel plate (MCP) imaging detector to be used in measurements of Doppler-shifted hydrogen Lyman-alpha line emission from Jupiter and the interplanetary medium. The detector is housed in a vacuum-tight stainless steel cylinder (to provide shielding from magnetic fields) with a MgF2 window. Operating at nominal voltage, the four plate configuration provides a gain of 1.2 x 10 exp 7 electrons per incident photon. The wedge-and-strip anode has two-dimensional imaging capabilities, with a resolution of 40 microns FWHM over a one centimeter diameter area. The detector has a high quantum efficiency while retaining a low background rate. A KBr photocathode is used to enhance the quantum efficiency of the bare MCPs to a value of 35 percent at Lyman-alpha.

  4. Statistical analysis of image data provided by two-dimensional gel electrophoresis for discovery proteomics.

    Science.gov (United States)

    Crossett, Ben; Edwards, Alistair V G; White, Melanie Y; Cordwell, Stuart J

    2008-01-01

    Standardized methods for the solubilization of proteins prior to proteomics analyses incorporating two-dimensional gel electrophoresis (2-DE) are essential for providing reproducible data that can be subjected to rigorous statistical interrogation for comparative studies investigating disease-genesis. In this chapter, we discuss the imaging and image analysis of proteins separated by 2-DE, in the context of determining protein abundance alterations related to a change in biochemical or biophysical conditions. We then describe the principles behind 2-DE gel statistical analysis, including subtraction of background noise, spot detection, gel matching, spot quantitation for data comparison, and statistical requirements to create meaningful gel data sets. We also emphasize the need to develop reproducible and robust protocols for protein sample preparation and 2-DE itself.

  5. Design and optimization of resistive anode for a two-dimensional imaging GEM detector

    Science.gov (United States)

    Ju, Xu-Dong; Dong, Ming-Yi; Zhao, Yi-Chen; Zhou, Chuan-Xing; Qun, Ou-Yang

    2016-08-01

    A resistive anode for two-dimensional imaging detectors, which consists of a series of high resistivity pads surrounded by low resistivity strips, can provide good spatial resolution while reducing the number of electronics channels required. The optimization of this kind of anode has been studied by both numerical simulations and experimental tests. It is found that to obtain good detector performance, the resistance ratio of the pads to the strips should be larger than 5, the nonuniformity of the pad surface resistivity should be less than 20%, a smaller pad width leads to a smaller spatial resolution, and when the pad width is 6 mm, the spatial resolution (σ) can reach about 105 μm. Based on the study results, a 2-D GEM detector prototype with optimized resistive anode is constructed and a good imaging performance is achieved. Supported by National Natural Science Foundation of China (11375219) and CAS Center for Excellence in Particle Physics (CCEPP)

  6. Digital optical phase conjugation for delivering two-dimensional images through turbid media.

    Science.gov (United States)

    Hillman, Timothy R; Yamauchi, Toyohiko; Choi, Wonshik; Dasari, Ramachandra R; Feld, Michael S; Park, YongKeun; Yaqoob, Zahid

    2013-01-01

    Optical transmission through complex media such as biological tissue is fundamentally limited by multiple light scattering. Precise control of the optical wavefield potentially holds the key to advancing a broad range of light-based techniques and applications for imaging or optical delivery. We present a simple and robust digital optical phase conjugation (DOPC) implementation for suppressing multiple light scattering. Utilizing wavefront shaping via a spatial light modulator (SLM), we demonstrate its turbidity-suppression capability by reconstructing the image of a complex two-dimensional wide-field target through a highly scattering medium. Employing an interferometer with a Sagnac-like ring design, we successfully overcome the challenging alignment and wavefront-matching constraints in DOPC, reflecting the requirement that the forward- and reverse-propagation paths through the turbid medium be identical. By measuring the output response to digital distortion of the SLM write pattern, we validate the sub-wavelength sensitivity of the system.

  7. Assessment of the reliability of reproducing two-dimensional resistivity models using an image processing technique.

    Science.gov (United States)

    Ishola, Kehinde S; Nawawi, Mohd Nm; Abdullah, Khiruddin; Sabri, Ali Idriss Aboubakar; Adiat, Kola Abdulnafiu

    2014-01-01

    This study attempts to combine the results of geophysical images obtained from three commonly used electrode configurations using an image processing technique in order to assess their capabilities to reproduce two-dimensional (2-D) resistivity models. All the inverse resistivity models were processed using the PCI Geomatica software package commonly used for remote sensing data sets. Preprocessing of the 2-D inverse models was carried out to facilitate further processing and statistical analyses. Four Raster layers were created, three of these layers were used for the input images and the fourth layer was used as the output of the combined images. The data sets were merged using basic statistical approach. Interpreted results show that all images resolved and reconstructed the essential features of the models. An assessment of the accuracy of the images for the four geologic models was performed using four criteria: the mean absolute error and mean percentage absolute error, resistivity values of the reconstructed blocks and their displacements from the true models. Generally, the blocks of the images of maximum approach give the least estimated errors. Also, the displacement of the reconstructed blocks from the true blocks is the least and the reconstructed resistivities of the blocks are closer to the true blocks than any other combined used. Thus, it is corroborated that when inverse resistivity models are combined, most reliable and detailed information about the geologic models is obtained than using individual data sets.

  8. Applications of Barcode Images by Enhancing the Two-Dimensional Recognition Rate

    Directory of Open Access Journals (Sweden)

    Kun-Hsien Lin

    2012-07-01

    Full Text Available The paper not only proposed the latest Two-Dimensional Barcodes Image-processing Module, but also captured the smallest camera screens (320 240 with different focal distances and tried to find out “Finder Pattern” for positioning images. Further, use CROBU (Conversion Ratio of Basic Unit the thesis proposed to convert 2-D barcodes into 1-pixel ratio to match images before judging recognition rate of 2-D barcodes through matching. Normally speaking, 2-D barcodes are deciphered and recognized by software while the thesis recognizes 2-D barcodes and enhances implementation speed up to 10-cm accurate max. using image matching. The 2-D barcodes image-processing module the thesis proposed does capture and standardize image with complicated background or raw edge, which enhances 2-D barcodes recognition rate. The main point of this study is to construct a platform to manage or suggest nutrients human body needs. The Quick Response Code image of 2-D barcodes represents vitamin and calories information. 2-D barcodes taken instantly by MATLAB and CCD camera can be used to list nutrients from foods you eat recently and suggest what else you should eat for the purpose of health management.

  9. Direct observation of two dimensional trace gas distributions with an airborne Imaging DOAS instrument

    Directory of Open Access Journals (Sweden)

    K.-P. Heue

    2008-11-01

    Full Text Available In many investigations of tropospheric chemistry information about the two dimensional distribution of trace gases on a small scale (e.g. tens to hundreds of metres is highly desirable. An airborne instrument based on imaging Differential Optical Absorption Spectroscopy has been built to map the two dimensional distribution of a series of relevant trace gases including NO2, HCHO, C2H2O2, H2O, O4, SO2, and BrO on a scale of 100 m.

    Here we report on the first tests of the novel aircraft instrument over the industrialised South African Highveld, where large variations in NO2 column densities in the immediate vicinity of several sources e.g. power plants or steel works, were measured. The observed patterns in the trace gas distribution are interpreted with respect to flux estimates, and it is seen that the fine resolution of the measurements allows separate sources in close proximity to one another to be distinguished.

  10. Quantitative estimation of brain atrophy and function with PET and MRI two-dimensional projection images

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Reiko; Uemura, Koji; Uchiyama, Akihiko [Waseda Univ., Tokyo (Japan). School of Science and Engineering; Toyama, Hinako; Ishii, Kenji; Senda, Michio

    2001-05-01

    The purpose of this paper is to estimate the extent of atrophy and the decline in brain function objectively and quantitatively. Two-dimensional (2D) projection images of three-dimensional (3D) transaxial images of positron emission tomography (PET) and magnetic resonance imaging (MRI) were made by means of the Mollweide method which keeps the area of the brain surface. A correlation image was generated between 2D projection images of MRI and cerebral blood flow (CBF) or {sup 18}F-fluorodeoxyglucose (FDG) PET images and the sulcus was extracted from the correlation image clustered by K-means method. Furthermore, the extent of atrophy was evaluated from the extracted sulcus on 2D-projection MRI and the cerebral cortical function such as blood flow or glucose metabolic rate was assessed in the cortex excluding sulcus on 2D-projection PET image, and then the relationship between the cerebral atrophy and function was evaluated. This method was applied to the two groups, the young and the aged normal subjects, and the relationship between the age and the rate of atrophy or the cerebral blood flow was investigated. This method was also applied to FDG-PET and MRI studies in the normal controls and in patients with corticobasal degeneration. The mean rate of atrophy in the aged group was found to be higher than that in the young. The mean value and the variance of the cerebral blood flow for the young are greater than those of the aged. The sulci were similarly extracted using either CBF or FDG PET images. The purposed method using 2-D projection images of MRI and PET is clinically useful for quantitative assessment of atrophic change and functional disorder of cerebral cortex. (author)

  11. Two-dimensional homography-based correction of positional errors in widefield MRT images

    CERN Document Server

    Nayak, Arvind; Shankar, N Udaya

    2010-01-01

    A steradian of the southern sky has been imaged at 151.5 MHz using the Mauritius Radio Telescope (MRT). These images show systematics in positional errors of sources when compared to source positions in the Molonglo Reference Catalogue (MRC). We have applied two-dimensional homography to correct for systematic positional errors in the image domain and thereby avoid re-processing the visibility data. Positions of bright (above 15-{\\sigma}) point sources, common to MRT catalogue and MRC, are used to set up an over-determined system to solve for the homography matrix. After correction the errors are found to be within 10% of the beamwidth for these bright sources and the systematics are eliminated from the images. This technique will be of relevance to the new generation radio telescopes where, owing to huge data rates, only images after a certain integration would be recorded as opposed to raw visibilities. It is also interesting to note how our investigations cued to possible errors in the array geometry. The ...

  12. Two-dimensional photon counting imaging detector based on PCB delay line anode

    Science.gov (United States)

    Zhu, Bingli; Bai, Yonglin; Lei, Fanpu; Bai, Xiaohong; Wang, Bo; Qin, Junjun; Cao, Weiwei; Gou, Yongsheng

    2016-11-01

    Delay line anode detector has high spatial resolution and high count rate. It has been an important technical means for single photon imaging from near earth space to deep space. A two dimensional delay line anode is designed using multilayer circuit board technology. A complete set of PCB delay line anode single photon detection system is established. The spatial resolution of the detector is theoretically analyzed. Moreover, the signal transmission characteristic of PCB delay line and the dark count rate of the detector are tested. Theoretical analysis and experimental results show that the detector spatial resolution is about 100um and the overall dark count rate is 4counts/cm2 at 2.3KV.

  13. Two-Dimensional Proton Chemical-Shift Imaging of Human Muscle Metabolites

    Science.gov (United States)

    Hu, Jiani; Willcott, M. Robert; Moore, Gregory J.

    1997-06-01

    Large lipid signals and strong susceptibility gradients introduced by muscle-bone interfaces represent major technical challenges forin vivoproton MRS of human muscle. Here, the demonstration of two-dimensional proton chemical-shift imaging of human muscle metabolites is presented. This technique utilizes a chemical-shift-selective method for water and lipid suppression and automatic shimming for optimal homogeneity of the magnetic field. The 2D1H CSI technique described facilitates the acquisition of high-spatial-resolution spectra, and allows one to acquire data from multiple muscle groups in a single experiment. A preliminary investigation utilizing this technique in healthy adult males (n= 4) revealed a highly significant difference in the ratio of the creatine to trimethylamine resonance between the fast and slow twitch muscle groups examined. The technique is robust, can be implemented on a commercial scanner with relative ease, and should prove to be a useful tool for both clinical and basic investigators.

  14. Myocardial Strain Imaging Based on Two-Dimensional Displacement Vector Measurement

    Science.gov (United States)

    Nitta, Naotaka; Shiina, Tsuyoshi

    2004-05-01

    The abnormalities of myocardial wall motion caused by changes in wall stiffness often appear in the early stage of ischemic heart disease. Since the myocardium exhibits complex and large motion, a two-dimensional (2D) or three-dimensional (3D) assessment of stiffness distribution is required for accurate diagnosis. Although a 3D assessment is ultimately required, as a stepped approach for practical use, we propose novel methods for tracking the 2D motion using a one-dimensional (1D) phased array and for assessing myocardial malfunction by visualizing the invariant of a strain tensor. The feasibilities of the proposed methods were evaluated by numerically simulating the short-axis imaging of a 3D myocardial model. This model includes a hard infarction located between 1 and 3 o’clock, which is difficult to detect by conventional tissue Doppler and strain rate imaging, and the motions of the model were assigned by referring to actual myocardial motion. These results revealed that the proposed imaging methods clearly depicted the hard infarction area which conventional imaging could not detect.

  15. Systematic errors in two-dimensional digital image correlation due to lens distortion

    Science.gov (United States)

    Pan, Bing; Yu, Liping; Wu, Dafang; Tang, Liqun

    2013-02-01

    Lens distortion practically presents in a real optical imaging system causing non-uniform geometric distortion in the recorded images, and gives rise to additional errors in the displacement and strain results measured by two-dimensional digital image correlation (2D-DIC). In this work, the systematic errors in the displacement and strain results measured by 2D-DIC due to lens distortion are investigated theoretically using the radial lens distortion model and experimentally through easy-to-implement rigid body, in-plane translation tests. Theoretical analysis shows that the displacement and strain errors at an interrogated image point are not only in linear proportion to the distortion coefficient of the camera lens used, but also depend on its distance relative to distortion center and its magnitude of displacement. To eliminate the systematic errors caused by lens distortion, a simple linear least-squares algorithm is proposed to estimate the distortion coefficient from the distorted displacement results of rigid body, in-plane translation tests, which can be used to correct the distorted displacement fields to obtain unbiased displacement and strain fields. Experimental results verify the correctness of the theoretical derivation and the effectiveness of the proposed lens distortion correction method.

  16. Two-dimensional accelerated MP-RAGE imaging with flexible linear reordering.

    Science.gov (United States)

    Brenner, Daniel; Stirnberg, Rüdiger; Pracht, Eberhard D; Stöcker, Tony

    2014-10-01

    Implementation of an accelerated Magnetization Prepared RApid Gradient Echo (MP-RAGE) sequence for T1 weighted neuroimaging; exploiting modern MRI technologies to minimize scan time while preserving the image quality. A custom MP-RAGE sequence was implemented on a state-of-the-art 3T MR scanner equipped with a 32-channel receiver array head coil. The sequence utilized a shifted CAIPIRINHA k y -k z under-sampling pattern combined with elliptical scanning and a two-dimensional view ordering scheme to achieve high parallel imaging acceleration factors at maintained image contrast. It could be shown that MP-RAGE accelerated in two k-space directions outperforms single direction acceleration, which is the common practice with standard view ordering. Applying the CAIPIRINHA technique in conjunction with elliptical scanning further increased this benefit. By combining MP-RAGE with CAIPIRINHA sampling and elliptical scanning, the scan time can be reduced from 4-5 min to 2-3 min with insignificant reduction in image quality.

  17. Two-Dimensional Hermite Filters Simplify the Description of High-Order Statistics of Natural Images

    Science.gov (United States)

    Hu, Qin; Victor, Jonathan D.

    2016-01-01

    Natural image statistics play a crucial role in shaping biological visual systems, understanding their function and design principles, and designing effective computer-vision algorithms. High-order statistics are critical for conveying local features, but they are challenging to study – largely because their number and variety is large. Here, via the use of two-dimensional Hermite (TDH) functions, we identify a covert symmetry in high-order statistics of natural images that simplifies this task. This emerges from the structure of TDH functions, which are an orthogonal set of functions that are organized into a hierarchy of ranks. Specifically, we find that the shape (skewness and kurtosis) of the distribution of filter coefficients depends only on the projection of the function onto a 1-dimensional subspace specific to each rank. The characterization of natural image statistics provided by TDH filter coefficients reflects both their phase and amplitude structure, and we suggest an intuitive interpretation for the special subspace within each rank. PMID:27713838

  18. Two-Dimensional Hermite Filters Simplify the Description of High-Order Statistics of Natural Images

    Directory of Open Access Journals (Sweden)

    Qin Hu

    2016-09-01

    Full Text Available Natural image statistics play a crucial role in shaping biological visual systems, understanding their function and design principles, and designing effective computer-vision algorithms. High-order statistics are critical for conveying local features but they are challenging to study, largely because their number and variety is large. Here, via the use of two-dimensional Hermite (TDH functions, we identify a covert symmetry in high-order statistics of natural images that simplifies this task. This emerges from the structure of TDH functions, which are an orthogonal set of functions that are organized into a hierarchy of ranks. Specifically, we find that the shape (skewness and kurtosis of the distribution of filter coefficients depends only on the projection of the function onto a one-dimensional subspace specific to each rank. The characterization of natural image statistics provided by TDH filter coefficients reflects both their phase and amplitude structure, and we suggest an intuitive interpretation for the special subspace within each rank.

  19. Highly confined, enhanced surface fluorescence imaging with two-dimensional silver nanoparticle sheets

    Energy Technology Data Exchange (ETDEWEB)

    Usukura, Eiji; Shinohara, Shuhei; Okamoto, Koichi; Tamada, Kaoru, E-mail: tamada@ms.ifoc.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 812-8581 (Japan); Lim, Jaehoon; Char, Kookheon [The National Creative Research Center for Intelligent Hybrid, School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2014-03-24

    A method of obtaining highly confined, enhanced surface fluorescence imaging is proposed using two-dimensional (2D) silver nanoparticle (AgMy) sheets. This technique is based on the localized surface plasmon resonance excited homogeneously on a 2D silver nanoparticle sheet. The AgMy sheets are fabricated at the air–water interface by self-assembly and transferred onto hydrophobic glass substrates. These sheets can enhance the fluorescence only when the excitation wavelength overlaps with the plasmon resonance wavelength. To confirm the validity of this technique, two separate test experiments are performed. One is the epifluorescence microscope imaging of a quantum dot 2D sheet on the AgMy 2D sheet with a SiO{sub 2} spacer layer, where the fluorescence is maximized with the 20 nm SiO{sub 2} layer, determined by the Förster resonance energy transfer distances. The second experiment is the imaging of a single fluorescence bead with a total internal reflection fluorescent microscope. We confirmed that the AgMy sheet provides a 4-fold increase in fluorescence with a 160-nm spatial resolution at 30 ms/frame snapshot. The AgMy sheet will be a powerful tool for high sensitivity and high-resolution real time bioimaging at nanointerfaces.

  20. Progress in two-dimensional arrays for real-time volumetric imaging.

    Science.gov (United States)

    Light, E D; Davidsen, R E; Fiering, J O; Hruschka, T A; Smith, S W

    1998-01-01

    The design, fabrication, and evaluation of two dimensional array transducers for real-time volumetric imaging are described. The transducers we have previously described operated at frequencies below 3 MHz and were unwieldy to the operator because of the interconnect schemes used in connecting to the transducer handle. Several new transducers have been developed using new connection technology. A 40 x 40 = 1,600 element, 3.5 MHz array was fabricated with 256 transmit and 256 receive elements. A 60 x 60 = 3,600 element 5.0 MHz array was constructed with 248 transmit and 256 receive elements. An 80 x 80 = 6,400 element, 2.5 MHz array was fabricated with 256 transmit and 208receive elements. 2-D transducer arrays were also developed for volumetric scanning in an intra cardiac catheter, a 10 x 10 = 100 element 5.0 MHz forward-looking array and an 11 x 13 = 143 element 5.0 MHz side-scanning array. The-6dB fractional bandwidths for the different arrays varied from 50% to 63%, and the 50 omega insertion loss for all the transducers was about-64 dB. The transducers were used to generate real-time volumetric images in phantoms and in vivo using the Duke University real time volumetric imaging system, which is capable of generating multiple planes at any desired angle and depth within the pyramidal volume.

  1. Combining Multiple Electrode Arrays for Two-Dimensional Electrical Resistivity Imaging Using the Unsupervised Classification Technique

    Science.gov (United States)

    Ishola, K. S.; Nawawi, M. N. M.; Abdullah, K.

    2015-06-01

    This article describes the use of k-means clustering, an unsupervised image classification technique, to help interpret subsurface targets. The k-means algorithm is employed to combine and classify the two-dimensional (2D) inverse resistivity models obtained from three different electrode arrays. The algorithm is initialized through the selection of the number of clusters, number of iterations and other parameters such as stopping criteria. Automatically, it seeks to find groups of closely related resistivity values that belong to the same cluster and are more similar to each other than resistivity values belonging to other clusters. The approach is applied to both synthetic and field data. The 2D postinversions of the resistivity data were preprocessed by resampling and interpolating to the same coordinate. Following the preprocessing, the three images are combined into a single classified image. All the image preprocessing, manipulation and analysis are performed using the PCI Geomatics software package. The results of the clustering and classification are presented as classified images. An assessment of the performance of the individual and combined images for the synthetic models is carried out using an error matrix, mean absolute error and mean absolute percent error. The estimated errors show that images obtained from maximum values of the reconstructed resistivity for the different models give the best representation of the true models. Additionally, the overall accuracy and kappa values show good agreement between the combined classified images and true models. Depending on the model, the overall accuracy ranges from 86 to 99 %, while the kappa coefficient is in the range of 54-98 %. Classified images with kappa coefficients greater than 0.8 show strong agreement, while images with kappa coefficients greater than 0.5 but less than 0.8 give moderate agreement. For the field data, the k-mean classifier produces images that incorporate structural features of

  2. Negative refraction and imaging of acoustic waves in a two-dimensional square chiral lattice structure

    Science.gov (United States)

    Zhao, Sheng-Dong; Wang, Yue-Sheng

    2016-05-01

    The negative refraction behavior and imaging effect for acoustic waves in a kind of two-dimensional square chiral lattice structure are studied in this paper. The unit cell of the proposed structure consists of four zigzag arms connected through a thin circular ring at the central part. The relation of the symmetry of the unit cell and the negative refraction phenomenon is investigated. Using the finite element method, we calculate the band structures and the equi-frequency surfaces of the system, and confirm the frequency range where the negative refraction is present. Due to the rotational symmetry of the unit cell, a phase difference is induced to the waves propagating from a point source through the structure to the other side. The phase difference is related to the width of the structure and the frequency of the source, so we can get a tunable deviated imaging. This kind of phenomenon is also demonstrated by the numerical simulation of two Gaussian beams that are symmetrical about the interface normal with the same incident angle, and the different negative refractive indexes are presented. Based on this special performance, a double-functional mirror-symmetrical slab is proposed for realizing acoustic focusing and beam separation.

  3. High Resolution Turntable Radar Imaging via Two Dimensional Deconvolution with Matrix Completion

    Science.gov (United States)

    Lu, Xinfei; Xia, Jie; Yin, Zhiping; Chen, Weidong

    2017-01-01

    Resolution is the bottleneck for the application of radar imaging, which is limited by the bandwidth for the range dimension and synthetic aperture for the cross-range dimension. The demand for high azimuth resolution inevitably results in a large amount of cross-range samplings, which always need a large number of transmit-receive channels or a long observation time. Compressive sensing (CS)-based methods could be used to reduce the samples, but suffer from the difficulty of designing the measurement matrix, and they are not robust enough in practical application. In this paper, based on the two-dimensional (2D) convolution model of the echo after matched filter (MF), we propose a novel 2D deconvolution algorithm for turntable radar to improve the radar imaging resolution. Additionally, in order to reduce the cross-range samples, we introduce a new matrix completion (MC) algorithm based on the hyperbolic tangent constraint to improve the performance of MC with undersampled data. Besides, we present a new way of echo matrix reconstruction for the situation that only partial cross-range data are observed and some columns of the echo matrix are missing. The new matrix has a better low rank property and needs just one operation of MC for all of the missing elements compared to the existing ways. Numerical simulations and experiments are carried out to demonstrate the effectiveness of the proposed method. PMID:28282904

  4. Two-dimensional point spread matrix of layered metal-dielectric imaging elements

    CERN Document Server

    Kotynski, Rafal; Krol, Karol; Panajotov, Krassimir

    2010-01-01

    We describe the change of the spatial distribution of the state of polarisation occurring during two-dimensional imaging through a multilayer and in particular through a layered metallic flat lens. Linear or circular polarisation of incident light is not preserved due to the difference in the amplitude transfer functions for the TM and TE polarisations. In effect, the transfer function and the point spread function that characterize 2D imaging through a multilayer both have a matrix form and cross-polarisation coupling is observed for spatially modulated beams with a linear or circular incident polarisation. The point spread function in a matrix form is used to characterise the resolution of the superlens for different polarisation states. We demonstrate how the 2D PSF may be used to design a simple diffractive nanoelement consisting of two radial slits. The structure assures the separation of non-diffracting radial beams originating from two slits in the mask and exhibits an interesting property of a backwar...

  5. Diaphragm assessment by two dimensional speckle tracking imaging in normal subjects.

    Science.gov (United States)

    Orde, Sam R; Boon, Andrea J; Firth, Daniel G; Villarraga, Hector R; Sekiguchi, Hiroshi

    2016-07-25

    Conventionally, ultrasonographic assessment of diaphragm contractility has involved measuring respiratory changes in diaphragm thickness (thickening fraction) using B-mode or caudal displacement with M-mode. Two-dimensional speckle-tracking has been increasingly used to assess muscle deformation ('strain') in echocardiography. We sought to determine in a pilot study if this technology could be utilized to analyze diaphragmatic contraction. Fifty healthy adult volunteers with normal exercise capacity underwent ultrasound imaging. A linear array transducer was used for the assessment of diaphragm thickness, thickening fraction (TF), and strain in the right anterior axillary line at approximately the ninth intercostal space. A phased array transducer was applied subcostally for the assessment of diaphragm displacement on the right mid-clavicular line. Diaphragmatic images were recorded from the end of expiration through the end of inspiration at 60 % maximal inspiratory capacity. Diaphragm strain was analyzed off-line by speckle tracking imaging. Blinded inter- and intra-rater variability was tested in 10 cases. Mean right diaphragm thickness at end-expiration (±SD: standard deviation) was 0.24 cm (±0.1), with TF of 45.1 % (±12) at 60 % peak inspiratory effort. Mean right diaphragm caudal displacement was 4.9 cm (±1). Mean right diaphragm strain was -40.3 % (±9). A moderate correlation was seen between longitudinal strain and TF (R(2) 0.44, p speckle tracking imaging was associated with conventional ultrasound measures of diaphragmatic function (TF and caudal displacement). Further clinical studies are warranted to investigate its clinical utility.

  6. Effects of temperature and irradiance on a benthic microalgal community: A combined two-dimensional oxygen and fluorescence imaging approach

    DEFF Research Database (Denmark)

    Hancke, Kasper; Sorrell, Brian Keith; Lund-Hansen, Lars Chresten

    2014-01-01

    The effects of temperature and light on both oxygen (O2) production and gross photosynthesis were resolved in a benthic microalgae community by combining two-dimensional (2D) imaging of O2 and variable chlorophyll a (Chl a) fluorescence. Images revealed a photosynthetically active community with ...

  7. SEMICONDUCTOR DEVICES: Two-dimensional pixel image lag simulation and optimization in a 4-T CMOS image sensor

    Science.gov (United States)

    Junting, Yu; Binqiao, Li; Pingping, Yu; Jiangtao, Xu; Cun, Mou

    2010-09-01

    Pixel image lag in a 4-T CMOS image sensor is analyzed and simulated in a two-dimensional model. Strategies of reducing image lag are discussed from transfer gate channel threshold voltage doping adjustment, PPD N-type doping dose/implant tilt adjustment and transfer gate operation voltage adjustment for signal electron transfer. With the computer analysis tool ISE-TCAD, simulation results show that minimum image lag can be obtained at a pinned photodiode n-type doping dose of 7.0 × 1012 cm-2, an implant tilt of -2°, a transfer gate channel doping dose of 3.0 × 1012 cm-2 and an operation voltage of 3.4 V. The conclusions of this theoretical analysis can be a guideline for pixel design to improve the performance of 4-T CMOS image sensors.

  8. TWO-DIMENSIONAL PARTICLE IMAGE VELOCIMETRY(PIV) MEASUREMENTS IN A TRANSPARENT CENTRIFUGAL PUMP

    Institute of Scientific and Technical Information of China (English)

    Yang Hua; Gu Chuangang; Wang Tong

    2005-01-01

    A special transparent centrifugal pump is designed. Detailed optical measurements of the flow inside the rotating passages of a five-bladed shroud centrifugal pump impeller have been performed by using two-dimensional particle image velocimetry (PIV). The flow is surveyed at three load conditions qv/qνd = 0.4, qν/qνd = 1.0, qν/qνd = 1.5, respectively. As a result, phase averaged PIV velocity vector maps on three planes between hub and shroud of the impeller are presented. At design load, the mean field of relative velocity is predominantly vane congruent, showing well-behaved flow without separation. The distributions of the relative velocity on different plane along the pump shaft are very different and there is always a low velocity zone near the pressure-side of the blade at both low and design flow rate, but the low-velocity-zone at the low flow rate is much larger than that at the design one. The study demonstrates that the PIV technique is efficient in providing reliable and detailed velocity data over a full impeller passage.

  9. Right ventricular dysfunction in patients with Brugada-like electrocardiography: a two dimensional strain imaging study

    Directory of Open Access Journals (Sweden)

    Murata Kazuya

    2011-11-01

    Full Text Available Abstract Background Sodium channel blockers augment ST-segment elevation in the right precordial leads in patients undergoing Brugada-type electrocardiography (ECG. However, their effect on echocardiographic features is not known. We address this by assessing global and regional ventricular function using conventional Doppler and two- dimensional (2D speckle tracking techniques. Methods Thirty-one patients with Brugada-type ECG were studied. A pure sodium channel blocker, pilsicainide, was used to provoke an ECG response. The percentage longitudinal systolic myocardial strain at the base of both the right ventricular (RV free wall and the interventricular septum wall was measured using 2D speckle tracking. Left ventricular (LV and RV myocardial performance (TEI indices were also measured. Results The pilsicainide challenge provoked a positive ECG response in 13 patients (inducible group. In the inducible group, longitudinal strain was significantly reduced only at the RV (-27.3 ± 5.4% vs -22.1 ± 3.6%, P P P Conclusions Temporal and spatial analysis using the TEI index and 2D strain imaging revealed the deterioration of global ventricular function associated with conduction disturbance and RV regional function in patients with Brugada-type ECG and coved type ST elevation due to administration of a sodium channel blocker.

  10. Contourlet textual features: improving the diagnosis of solitary pulmonary nodules in two dimensional CT images.

    Directory of Open Access Journals (Sweden)

    Jingjing Wang

    Full Text Available To determine the value of contourlet textural features obtained from solitary pulmonary nodules in two dimensional CT images used in diagnoses of lung cancer.A total of 6,299 CT images were acquired from 336 patients, with 1,454 benign pulmonary nodule images from 84 patients (50 male, 34 female and 4,845 malignant from 252 patients (150 male, 102 female. Further to this, nineteen patient information categories, which included seven demographic parameters and twelve morphological features, were also collected. A contourlet was used to extract fourteen types of textural features. These were then used to establish three support vector machine models. One comprised a database constructed of nineteen collected patient information categories, another included contourlet textural features and the third one contained both sets of information. Ten-fold cross-validation was used to evaluate the diagnosis results for the three databases, with sensitivity, specificity, accuracy, the area under the curve (AUC, precision, Youden index, and F-measure were used as the assessment criteria. In addition, the synthetic minority over-sampling technique (SMOTE was used to preprocess the unbalanced data.Using a database containing textural features and patient information, sensitivity, specificity, accuracy, AUC, precision, Youden index, and F-measure were: 0.95, 0.71, 0.89, 0.89, 0.92, 0.66, and 0.93 respectively. These results were higher than results derived using the database without textural features (0.82, 0.47, 0.74, 0.67, 0.84, 0.29, and 0.83 respectively as well as the database comprising only textural features (0.81, 0.64, 0.67, 0.72, 0.88, 0.44, and 0.85 respectively. Using the SMOTE as a pre-processing procedure, new balanced database generated, including observations of 5,816 benign ROIs and 5,815 malignant ROIs, and accuracy was 0.93.Our results indicate that the combined contourlet textural features of solitary pulmonary nodules in CT images with

  11. Transformation diffusion reconstruction of three-dimensional histology volumes from two-dimensional image stacks.

    Science.gov (United States)

    Casero, Ramón; Siedlecka, Urszula; Jones, Elizabeth S; Gruscheski, Lena; Gibb, Matthew; Schneider, Jürgen E; Kohl, Peter; Grau, Vicente

    2017-05-01

    Traditional histology is the gold standard for tissue studies, but it is intrinsically reliant on two-dimensional (2D) images. Study of volumetric tissue samples such as whole hearts produces a stack of misaligned and distorted 2D images that need to be reconstructed to recover a congruent volume with the original sample's shape. In this paper, we develop a mathematical framework called Transformation Diffusion (TD) for stack alignment refinement as a solution to the heat diffusion equation. This general framework does not require contour segmentation, is independent of the registration method used, and is trivially parallelizable. After the first stack sweep, we also replace registration operations by operations in the space of transformations, several orders of magnitude faster and less memory-consuming. Implementing TD with operations in the space of transformations produces our Transformation Diffusion Reconstruction (TDR) algorithm, applicable to general transformations that are closed under inversion and composition. In particular, we provide formulas for translation and affine transformations. We also propose an Approximated TDR (ATDR) algorithm that extends the same principles to tensor-product B-spline transformations. Using TDR and ATDR, we reconstruct a full mouse heart at pixel size 0.92µm×0.92µm, cut 10µm thick, spaced 20µm (84G). Our algorithms employ only local information from transformations between neighboring slices, but the TD framework allows theoretical analysis of the refinement as applying a global Gaussian low-pass filter to the unknown stack misalignments. We also show that reconstruction without an external reference produces large shape artifacts in a cardiac specimen while still optimizing slice-to-slice alignment. To overcome this problem, we use a pre-cutting blockface imaging process previously developed by our group that takes advantage of Brewster's angle and a polarizer to capture the outline of only the topmost layer of wax

  12. Determination of grain-size distribution function using two-dimensional Fourier transforms of tone-pulse-encoded images

    Science.gov (United States)

    Generazio, E. R.

    1988-01-01

    Microstructural images may be tone pulse encoded and subsequently Fourier transformed to determine the two-dimensional density of frequency components. A theory is developed relating the density of frequency components to the density of length components. The density of length components corresponds directly to the actual grain-size distribution function from which the mean grain shape, size, and orientation can be obtained.

  13. Determination of grain size distribution function using two-dimensional Fourier transforms of tone pulse encoded images

    Science.gov (United States)

    Generazio, E. R.

    1986-01-01

    Microstructural images may be tone pulse encoded and subsequently Fourier transformed to determine the two-dimensional density of frequency components. A theory is developed relating the density of frequency components to the density of length components. The density of length components corresponds directly to the actual grain size distribution function from which the mean grain shape, size, and orientation can be obtained.

  14. Light Focusing and Two-Dimensional Imaging Through Scattering Media using the Photoacoustic Transmission-Matrix with an Ultrasound Array

    CERN Document Server

    Chaigne, Thomas; Katz, Ori; Bossy, Emmanuel; Gigan, Sylvain

    2014-01-01

    We implement the photoacoustic transmission-matrix approach on a two-dimensional photoacoustic imaging system, using a 15 MHz linear ultrasound array. Using a black leaf skeleton as a complex absorbing structure, we demonstrate that the photoacoustic transmission-matrix approach allows to reveal structural features that are invisible in conventional photoacoustic images, as well as to selectively control light focusing on absorbing targets, leading to a local enhancement of the photoacoustic signal.

  15. Development of a two-dimensional imaging GEM detector using the resistive anode readout method with $6\\times6$ cells

    CERN Document Server

    Ju, Xu-Dong; Zhou, Chuan-Xing; Dong, Jing; Zhao, Yu-Bin; Zhang, Hong-Yu; Qi, Hui-Rong; Ou-Yang, Qun

    2016-01-01

    We report the application of the resistive anode readout method on a two dimensional imaging GEM detector. The resistive anode consists $6\\times6$ cells with the cell size $6~\\mathrm{mm}\\times6~\\mathrm{mm}$. New electronics and DAQ system are used to process the signals from 49 readout channels. The detector has been tested by using the X-ray tube (8~keV). The spatial resolution of the detector is about $103.46~\\mathrm{{\\mu}m}$ with the signal part $66.41~\\mathrm{{\\mu}m}$. The nonlinearity of the detector is less than $0.5\\%$. A good two dimensional imaging capability is achieved as well. The performances of the detector show the prospect of the resistive anode readout method for the large readout area imaging detectors.

  16. Coding/decoding two-dimensional images with orbital angular momentum of light.

    Science.gov (United States)

    Chu, Jiaqi; Li, Xuefeng; Smithwick, Quinn; Chu, Daping

    2016-04-01

    We investigate encoding and decoding of two-dimensional information using the orbital angular momentum (OAM) of light. Spiral phase plates and phase-only spatial light modulators are used in encoding and decoding of OAM states, respectively. We show that off-axis points and spatial variables encoded with a given OAM state can be recovered through decoding with the corresponding complimentary OAM state.

  17. Gray matter imaging in multiple sclerosis: what have we learned?

    Directory of Open Access Journals (Sweden)

    Hulst Hanneke E

    2011-12-01

    Full Text Available Abstract At the early onset of the 20th century, several studies already reported that the gray matter was implicated in the histopathology of multiple sclerosis (MS. However, as white matter pathology long received predominant attention in this disease, and histological staining techniques for detecting myelin in the gray matter were suboptimal, it was not until the beginning of the 21st century that the true extent and importance of gray matter pathology in MS was finally recognized. Gray matter damage was shown to be frequent and extensive, and more pronounced in the progressive disease phases. Several studies subsequently demonstrated that the histopathology of gray matter lesions differs from that of white matter lesions. Unfortunately, imaging of pathology in gray matter structures proved to be difficult, especially when using conventional magnetic resonance imaging (MRI techniques. However, with the recent introduction of several more advanced MRI techniques, the detection of cortical and subcortical damage in MS has considerably improved. This has important consequences for studying the clinical correlates of gray matter damage. In this review, we provide an overview of what has been learned about imaging of gray matter damage in MS, and offer a brief perspective with regards to future developments in this field.

  18. Single-shot x-ray differential phase-contrast and diffraction imaging using two-dimensional transmission gratings.

    Science.gov (United States)

    Wen, Harold H; Bennett, Eric E; Kopace, Rael; Stein, Ashley F; Pai, Vinay

    2010-06-15

    We describe an x-ray differential phase-contrast imaging method based on two-dimensional transmission gratings that are directly resolved by an x-ray camera. X-ray refraction and diffraction in the sample lead to variations of the positions and amplitudes of the grating fringes on the camera. These effects can be quantified through spatial harmonic analysis. The use of 2D gratings allows differential phase contrast in several directions to be obtained from a single image. When compared to previous grating-based interferometry methods, this approach obviates the need for multiple exposures and separate measurements for different directions and thereby accelerates imaging speed.

  19. A modified CoSaMP algorithm for electromagnetic imaging of two dimensional domains

    KAUST Repository

    Sandhu, Ali Imran

    2017-05-13

    The compressive sampling matching pursuit (CoSaMP) algorithm is used for solving the electromagnetic inverse scattering problem on two-dimensional sparse domains. Since the scattering matrix, which is computed by sampling the Green function, does not satisfy the restricted isometry property, a damping parameter is added to the diagonal entries of the matrix to make the CoSaMP work. The damping factor can be selected based on the level of noise in the measurements. Numerical experiments, which demonstrate the accuracy and applicability of the proposed algorithm, are presented.

  20. Bayesian reconstruction of P(r) directly from two-dimensional detector images via a Markov chain Monte Carlo method.

    Science.gov (United States)

    Paul, Sudeshna; Friedman, Alan M; Bailey-Kellogg, Chris; Craig, Bruce A

    2013-04-01

    The interatomic distance distribution, P(r), is a valuable tool for evaluating the structure of a molecule in solution and represents the maximum structural information that can be derived from solution scattering data without further assumptions. Most current instrumentation for scattering experiments (typically CCD detectors) generates a finely pixelated two-dimensional image. In contin-uation of the standard practice with earlier one-dimensional detectors, these images are typically reduced to a one-dimensional profile of scattering inten-sities, I(q), by circular averaging of the two-dimensional image. Indirect Fourier transformation methods are then used to reconstruct P(r) from I(q). Substantial advantages in data analysis, however, could be achieved by directly estimating the P(r) curve from the two-dimensional images. This article describes a Bayesian framework, using a Markov chain Monte Carlo method, for estimating the parameters of the indirect transform, and thus P(r), directly from the two-dimensional images. Using simulated detector images, it is demonstrated that this method yields P(r) curves nearly identical to the reference P(r). Furthermore, an approach for evaluating spatially correlated errors (such as those that arise from a detector point spread function) is evaluated. Accounting for these errors further improves the precision of the P(r) estimation. Experimental scattering data, where no ground truth reference P(r) is available, are used to demonstrate that this method yields a scattering and detector model that more closely reflects the two-dimensional data, as judged by smaller residuals in cross-validation, than P(r) obtained by indirect transformation of a one-dimensional profile. Finally, the method allows concurrent estimation of the beam center and Dmax, the longest interatomic distance in P(r), as part of the Bayesian Markov chain Monte Carlo method, reducing experimental effort and providing a well defined protocol for these

  1. Two-dimensional graphene as a matrix for MALDI imaging mass spectrometry.

    Science.gov (United States)

    Friesen, William L; Schultz, Brian J; Destino, Joel F; Alivio, Theodore E G; Steet, Joseph R; Banerjee, Sarbajit; Wood, Troy D

    2015-11-01

    Here, a matrix using two-dimensional (2D) graphene is demonstrated for the first time in the context of MALDI IMS using a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Although graphene flakes have been used previously in MALDI, it is described here how a single 2D layer of graphene is applied directly on top of rat brain sections and soybean leaves. Several classes of molecules are desorbed and ionized off of the surface of the tissues examined using 2D graphene, with minimal background interference from the matrix. Moreover, no solvents are employed in application of 2D graphene, eliminating the potential for analyte diffusion in liquid droplets during matrix application. Because 2D graphene is an elemental form of carbon, an additional advantage is its high compatibility with the long duration needed for many IMS experiments. Graphical Abstract ᅟ.

  2. Two-Dimensional Spatial Imaging of Charge Transport in Germanium Crystals at Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Moffatt, Robert [Stanford U.

    2016-01-01

    In this dissertation, I describe a novel apparatus for studying the transport of charge in semiconductors at cryogenic temperatures. The motivation to conduct this experiment originated from an asymmetry observed between the behavior of electrons and holes in the germanium detector crystals used by the Cryogenic Dark Matter Search (CDMS). This asymmetry is a consequence of the anisotropic propagation of electrons in germanium at cryogenic temperatures. To better model our detectors, we incorporated this effect into our Monte Carlo simulations of charge transport. The purpose of the experiment described in this dissertation is to test those models in detail. Our measurements have allowed us to discover a shortcoming in our most recent Monte Carlo simulations of electrons in germanium. This discovery would not have been possible without the measurement of the full, two-dimensional charge distribution, which our experimental apparatus has allowed for the first time at cryogenic temperatures.

  3. Two-Dimensional Graphene as a Matrix for MALDI Imaging Mass Spectrometry

    Science.gov (United States)

    Friesen, William L.; Schultz, Brian J.; Destino, Joel F.; Alivio, Theodore E. G.; Steet, Joseph R.; Banerjee, Sarbajit; Wood, Troy D.

    2015-11-01

    Here, a matrix using two-dimensional (2D) graphene is demonstrated for the first time in the context of MALDI IMS using a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Although graphene flakes have been used previously in MALDI, it is described here how a single 2D layer of graphene is applied directly on top of rat brain sections and soybean leaves. Several classes of molecules are desorbed and ionized off of the surface of the tissues examined using 2D graphene, with minimal background interference from the matrix. Moreover, no solvents are employed in application of 2D graphene, eliminating the potential for analyte diffusion in liquid droplets during matrix application. Because 2D graphene is an elemental form of carbon, an additional advantage is its high compatibility with the long duration needed for many IMS experiments.

  4. A new method for information retrieval in two-dimensional grating-based X-ray phase contrast imaging

    Institute of Scientific and Technical Information of China (English)

    Wang Zhi-Li; Gao Kun; Chen Jian; Ge Xin; Zhu Pei-Ping; Tian Yang-Chao; Wu Zi-Yu

    2012-01-01

    Grating-based X-ray phase contrast imaging has been demonstrated to be an extremely powerful phase-sensitive imaging technique.By using two-dimensional (2D) gratings,the observable contrast is extended to two refraction directions.Recently,we have developed a novel reverse-projection (RP) method,which is capable of retrieving the object information efficiently with one-dimensional (1D) grating-based phase contrast imaging.In this contribution,we present its extension to the 2D grating-based X-ray phase contrast imaging,named the two-dimensional reverseprojection (2D-RP) method,for information retrieval.The method takes into account the nonlinear contributions of two refraction directions and allows the retrieval of the absorption,the horizontal and the vertical refraction images.The obtained information can be used for the reconstruction of the three-dimensional phase gradient field,and for an improved phase map retrieval and reconstruction.Numerical experiments are carried out,and the results confirm the validity of the 2D-RP method.

  5. Toward two-dimensional nanometer resolution hard X-ray differential-interference-contrast imaging using modified photon sieves.

    Science.gov (United States)

    Xie, Changqing; Zhu, Xiaoli; Li, Hailiang; Shi, Lina; Hua, Yilei; Liu, Ming

    2012-02-15

    In this Letter, we report a significant step forward in the design of single-optical-element optics for two-dimensional (2D) hard X-ray differential-interference-contrast (DIC) imaging based on modified photon sieves (MPSs). MPSs were obtained by a modified optic, i.e., combining two overlaid binary gratings and a photon sieve through two logical XOR operations. The superior performance of MPSs was demonstrated. Compared to Fresnel zone plates-based DIC diffractive optical elements (DOEs), which help to improve contrast only in one direction, MPSs can provide better resolution and 2D DIC imaging. Compared to normal photon sieves, MPSs are capable of imaging at a significantly higher image contrast. We anticipate that MPSs can provide a complementary and versatile high-resolution nondestructive imaging tool for ultra-large-scale integrated circuits at 45 nm node and below.

  6. Reference data representative of normal findings at two-dimensional and three-dimensional gray-scale ultrasound examination of the cervix from 17 to 41 weeks' gestation.

    OpenAIRE

    Rovas, Linas; Sladkevicius, Povilas; Strobel, E; Valentin, Lil

    2006-01-01

    Objectives To create reference values representative of normal findings on two-dimensional (2D) and three-dimensional (3D) transvaginal ultrasound (TVS) examination of the cervix from 17 to 41 weeks' gestation and to determine the agreement between cervical measurements taken by 2D and 3D TVS. Methods Cross-sectional study covering 17 to 41 weeks in 419 nulliparous and 360 parous women who delivered at term and who underwent 2D and 3D TVS examination of the uterine cervix. We examined app...

  7. Two-dimensional inverse planning and delivery with a preclinical image guided microirradiator

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, James M. P. [Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3E2, Canada and Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Lindsay, Patricia E. [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2M9, Canada and Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Jaffray, David A. [Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); The Techna Institute for the Advancement of Technology for Health, Toronto, Ontario M5G 1P5 (Canada)

    2013-10-15

    Purpose: Recent advances in preclinical radiotherapy systems have provided the foundation for scaling many of the elements of clinical radiation therapy practice to the dimensions and energy demanded in small animal studies. Such systems support the technical capabilities to accurately deliver highly complex dose distributions, but methods to optimize and deliver such distributions remain in their infancy. This study developed an optimization method based on empirically measured two-dimensional dose kernel measurements to deliver arbitrary planar dose distributions on a recently developed small animal radiotherapy platform.Methods: A two-dimensional dose kernel was measured with repeated radiochromic film measurements for the circular 1 mm diameter fixed collimator of the small animal radiotherapy system at 1 cm depth in a solid water phantom. This kernel was utilized in a sequential quadratic programming optimization framework to determine optimal beam positions and weights to deliver an arbitrary desired dose distribution. The positions and weights were then translated to a set of stage motions to automatically deliver the optimized dose distribution. End-to-end efficacy of the framework was quantified through five repeated deliveries of two dosimetric challenges: (1) a 5 mm radius bullseye distribution, and (2) a “sock” distribution contained within a 9 × 13 mm bounding box incorporating rectangular, semicircular, and exponentially decaying geometric constructs and a rectangular linear dose gradient region. These two challenges were designed to gauge targeting, geometric, and dosimetric fidelity.Results: Optimization of the bullseye and sock distributions required 2.1 and 5.9 min and utilized 50 and 77 individual beams for delivery, respectively. Automated delivery of the resulting optimized distributions, validated using radiochromic film measurements, revealed an average targeting accuracy of 0.32 mm, and a dosimetric delivery error along four line

  8. Local imaging of high mobility two-dimensional electron systems with virtual scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pelliccione, M. [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, University of California, Santa Barbara, Santa Barbara, California 93106 (United States); Bartel, J.; Goldhaber-Gordon, D. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States); Sciambi, A. [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Pfeiffer, L. N.; West, K. W. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2014-11-03

    Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called “virtual scanning tunneling microscopy” that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

  9. Probing of two-dimensional grid patterns by means of camera-based image processing

    Science.gov (United States)

    Schroeck, Martin; Doiron, Theodore D.

    2000-03-01

    Camera based probes and machine vision have found increased use in coordinate measuring machines over the past years and the calibration of artifacts for these probes has become an important task for NIST. Until recently these artifacts have been calibrated using one or two dimensional measuring machines with electro-optic microscopes or scanning devices as probes. These sensors evaluate only a small section of the edge of a grid mark, and irregularities in this particular spot from local deformations or contamination influence the measurement result. Since these measurements result in a single number based on the entire field of view, the influence of small irregularities are not easily detected. Since different probes scan different parts of the grid mark edge they may give systematically different positions of the mark. The conversion to video based sensors has allowed more flexibility it edge detection, although most instruments still use least squares fits as the substitute geometry of straight edges. This method is very susceptible to noise and edge irregularities. We present some experiments for finding the sub-pixel edge point locations and fitting the set of edge points to a line using a fairly simple least sum of absolute deviations fit. Data from a high accuracy 2D measuring machine is used to show the strengths of the algorithms.

  10. Complete Two-dimensional Muellermetric Imaging of Biological Tissue Using Heterodyned Optical Coherence Tomography

    CERN Document Server

    Liu, Xue; Shahriar, M S

    2010-01-01

    A polarization-sensitive optical coherence tomography system based on heterodyning and filtering techniques is built to perform Stokesmetric imaging of different layers of depths in a porcine tendon sample. The complete 4\\times4 backscattering Muellermetric images of one layer are acquired using such a system. The images reveal information indiscernible from a conventional OCT system.

  11. Dynamics of laser-imploded core plasmas observed by ultrafast two-dimensional x-ray imaging with animation display

    Energy Technology Data Exchange (ETDEWEB)

    Heya, Manabu; Shiraga, Hiroyuki; Shimada, Kyoko; Miyanaga, Noriaki; Takabe, Hideaki; Yamanaka, Tatsuhiko; Mima, Kunioki [Osaka Univ., Inst. of Laser Engineering, Suita, Osaka (Japan)

    1999-05-01

    In order to observe time-resolved, two-dimensional (2D) spatial distribution of x rays emitted from core plasmas at the final stage of the implosion, we have developed a multi-imaging x-ray streak camera (MIXS) and a multi-channel MIXS (McMIXS) methods as new ultrafast 2D x-ray imaging techniques. The observed time-resolved 2D x-ray and electron-temperature images of core plasmas, which are sequentially changing with time, have been displayed by using an animation method. Temporal evolutions of nonuniform structures, including shape, size, and movement of core plasmas can be observed instinctively with the animated display. The ultrafast 2D x-ray imaging with the animation display is a new powerful tool for understanding the dynamics of laser-imploded core plasmas. (author)

  12. Multiplanar and two-dimensional imaging of central airway stenting with multidetector computed tomography

    Directory of Open Access Journals (Sweden)

    Ozgul Mehmet

    2012-08-01

    Full Text Available Abstract Background Multidetector computed tomography (MDCT provides guidance for primary screening of the central airways. The aim of our study was assessing the contribution of multidetector computed tomography- two dimensional reconstruction in the management of patients with tracheobronchial stenosis prior to the procedure and during a short follow up period of 3 months after the endobronchial treatment. Methods This is a retrospective study with data collected from an electronic database and from the medical records. Patients evaluated with MDCT and who had undergone a stenting procedure were included. A Philips RSGDT 07605 model MDCT was used, and slice thickness, 3 mm; overlap, 1.5 mm; matrix, 512x512; mass, 90 and kV, 120 were evaluated. The diameters of the airways 10 mm proximal and 10 mm distal to the obstruction were measured and the stent diameter (D was determined from the average between D upper and D lower. Results Fifty-six patients, 14 (25% women and 42 (75% men, mean age 55.3 ± 13.2 years (range: 16-79 years, were assessed by MDCT and then treated with placement of an endobronchial stent. A computed tomography review was made with 6 detector Philips RSGDT 07605 multidetector computed tomography device. Endobronchial therapy was provided for the patients with endoluminal lesions. Stents were placed into the area of stenosis in patients with external compression after dilatation and debulking procedures had been carried out. In one patient the migration of a stent was detected during the follow up period by using MDCT. Conclusions MDCT helps to define stent size, length and type in patients who are suitable for endobronchial stinting. This is a non-invasive, reliable method that helps decisions about optimal stent size and position, thus reducing complications.

  13. Bi-directional two-dimensional/three-dimensional convertible integral imaging using scattering polarizer

    Science.gov (United States)

    Yeom, Jiwoon; Hong, Jisoo; Park, Soon-gi; Min, Sung-Wook; Lee, Byoungho

    2012-10-01

    A bi-directional 2D/3D convertible integral imaging system is proposed. Two optical modules composed of a scattering polarizer and a linear polarizer are adopted, and 2D or 3D mode operation is easily changed by converting polarization states of the projected images. In the 2D mode, the incident light is scattered at the scattering polarizer and the scattered light facing the lens-array is blocked, a 2D image is observable only at the same side as the projector. In the 3D mode, the incident light with the transmission polarization is directly projected onto a lens-array, and the 3D images are integrated. Our proposed system is able to display the 3D images as well as the 2D images for the observers who are placed in front and rear side of the system.

  14. Choosing parameters for Rényi and Tsallis entropies within a two-dimensional multilevel image segmentation framework

    Science.gov (United States)

    Ben Ishak, Anis

    2017-01-01

    In this work, the effect of Rényi and Tsallis entropies' parameters on the image segmentation quality within a two-dimensional multilevel thresholding framework is assessed and analyzed. The problems of automatically tuning entropy's parameter and determining the optimal thresholding values are solved in a single task. This is done by using the Quantum Genetic Algorithm (QGA). The numerical experiments conducted on different types of images demonstrated that Rényi and Tsallis entropies perform approximately similarly, and they are optimal when their parameters are null. Moreover, it was shown that optimizing the entropy does not lead to maximize the Peak Signal to Noise Ratio (PSNR) and the Structural SIMilarity (SSIM) criteria. Then, we have proved that these two criteria are not sufficiently consistent with human visual perception. Finally, the comparative study performed on some synthetic and real images demonstrated the effectiveness of the proposed method.

  15. Two-dimensional X-ray imaging using plastic scintillating fiber array

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Due to its low cost,flexibility and convenience for long distance dala transfer,plastic scintillation fiber (PSF)have been increasingly used in building detectors or sensors for detecting various radiations and imaging.In this work,the performance of using PSF coupled with charge-coupled devices(CCD)to build are adetectors for 2D X-ray imaging is studied.We describe the experimental setup and show the obtained images from CCD.Modulation Transfer Function(MTF)of the PSF array is also presented and compared to earlier reports.

  16. High-resolution two-dimensional image upconversion of incoherent light

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    2010-01-01

    We consider a technique for high-resolution image upconversion of thermal light. Experimentally, we demonstrate cw upconversion with a resolution of more than 200 × 1000 pixels of thermally illuminated objects. This is the first demonstration (to our knowledge) of high-resolution cw image...... upconversion. The upconversion method promises an alternative route to high-quantum-efficiency all-optical imaging in the mid-IR wavelength region and beyond using standard CCD cameras. A particular advantage of CCD cameras compared to state-of-the-art thermal cameras is the possibility to tailor and tune...

  17. Two-dimensional catheter arrays for real-time intracardiac volumetric imaging

    Science.gov (United States)

    Light, Edward D.; Fiering, Jason O.; Lee, Warren; Wolf, Patrick D.; Smith, Stephen W.

    1999-06-01

    We have previously described 2D arrays of several thousand elements operating up to 5.0 MHz for transthoracic cardiac imaging. Lately, there has been interest in developing catheter based intracardiac imaging systems to aid in the precise tracking of anatomical features for improved diagnoses and therapies. We have constructed several arrays for real time intracardiac volumetric imaging based upon two different designs; a 10 X 10 equals 100 element 5.0 MHz forward looking 2D array, and a 13 X 11 equals 143 element 5.0 MHz 2D array for side scanning applications.

  18. Accelerated two-dimensional cine DENSE cardiovascular magnetic resonance using compressed sensing and parallel imaging.

    Science.gov (United States)

    Chen, Xiao; Yang, Yang; Cai, Xiaoying; Auger, Daniel A; Meyer, Craig H; Salerno, Michael; Epstein, Frederick H

    2016-06-14

    Cine Displacement Encoding with Stimulated Echoes (DENSE) provides accurate quantitative imaging of cardiac mechanics with rapid displacement and strain analysis; however, image acquisition times are relatively long. Compressed sensing (CS) with parallel imaging (PI) can generally provide high-quality images recovered from data sampled below the Nyquist rate. The purposes of the present study were to develop CS-PI-accelerated acquisition and reconstruction methods for cine DENSE, to assess their accuracy for cardiac imaging using retrospective undersampling, and to demonstrate their feasibility for prospectively-accelerated 2D cine DENSE imaging in a single breathhold. An accelerated cine DENSE sequence with variable-density spiral k-space sampling and golden angle rotations through time was implemented. A CS method, Block LOw-rank Sparsity with Motion-guidance (BLOSM), was combined with sensitivity encoding (SENSE) for the reconstruction of under-sampled multi-coil spiral data. Seven healthy volunteers and 7 patients underwent 2D cine DENSE imaging with fully-sampled acquisitions (14-26 heartbeats in duration) and with prospectively rate-2 and rate-4 accelerated acquisitions (14 and 8 heartbeats in duration). Retrospectively- and prospectively-accelerated data were reconstructed using BLOSM-SENSE and SENSE. Image quality of retrospectively-undersampled data was quantified using the relative root mean square error (rRMSE). Myocardial displacement and circumferential strain were computed for functional assessment, and linear correlation and Bland-Altman analyses were used to compare accelerated acquisitions to fully-sampled reference datasets. For retrospectively-undersampled data, BLOSM-SENSE provided similar or lower rRMSE at rate-2 and lower rRMSE at rate-4 acceleration compared to SENSE (p cine DENSE provided good image quality and expected values of displacement and strain. BLOSM-SENSE-accelerated spiral cine DENSE imaging with 2D displacement encoding can be

  19. Electron beam dispersion measurements in nitrogen using two-dimensional imaging of N2(+) fluorescence

    Science.gov (United States)

    Clapp, L. H.; Twiss, R. G.; Cattolica, R. J.

    Experimental results are presented related to the radial spread of fluorescence excited by 10 and 20 KeV electron beams passing through nonflowing rarefied nitrogen at 293 K. An imaging technique for obtaining species distributions from measured beam-excited fluorescence is described, based on a signal inversion scheme mathematically equivalent to the inversion of the Abel integral equation. From fluorescence image data, measurements of beam radius, integrated signal intensity, and spatially resolved distributions of N2(+) first-negative-band fluorescence-emitting species have been made. Data are compared with earlier measurements and with an heuristic beam spread model.

  20. A method for the frequency control in time-resolved two-dimensional gigahertz surface acoustic wave imaging

    Directory of Open Access Journals (Sweden)

    Shogo Kaneko

    2014-01-01

    Full Text Available We describe an extension of the time-resolved two-dimensional gigahertz surface acoustic wave imaging based on the optical pump-probe technique with periodic light source at a fixed repetition frequency. Usually such imaging measurement may generate and detect acoustic waves with their frequencies only at or near the integer multiples of the repetition frequency. Here we propose a method which utilizes the amplitude modulation of the excitation pulse train to modify the generation frequency free from the mentioned limitation, and allows for the first time the discrimination of the resulted upper- and lower-side-band frequency components in the detection. The validity of the method is demonstrated in a simple measurement on an isotropic glass plate covered by a metal thin film to extract the dispersion curves of the surface acoustic waves.

  1. Two-dimensional Fast ESPRIT Algorithm for Linear Array SAR Imaging

    Directory of Open Access Journals (Sweden)

    Zhao Yi-chao

    2015-10-01

    Full Text Available The linear array Synthetic Aperture Radar (SAR system is a popular research tool, because it can realize three-dimensional imaging. However, owning to limitations of the aircraft platform and actual conditions, resolution improvement is difficult in cross-track and along-track directions. In this study, a twodimensional fast Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT algorithm for linear array SAR imaging is proposed to overcome these limitations. This approach combines the Gerschgorin disks method and the ESPRIT algorithm to estimate the positions of scatterers in cross and along-rack directions. Moreover, the reflectivity of scatterers is obtained by a modified pairing method based on “region growing”, replacing the least-squares method. The simulation results demonstrate the applicability of the algorithm with high resolution, quick calculation, and good real-time response.

  2. Two-dimensional GEM imaging detector with delay-line readout

    Science.gov (United States)

    Guedes, G. P.; Breskin, A.; Chechik, R.; Vartsky, D.; Bar, D.; Barbosa, A. F.; Marinho, P. R. B.

    2003-11-01

    A 100×100 mm 2 2D imaging detector, based on a triple-GEM gaseous multiplier, striped x- y readout anode and discrete delay-line readout, is presented. The fast (2.1 ns tap -1) delay-line circuit was designed to match the anode-charge signal profile, namely its rise-time and length. The detector's imaging capability was systematically studied in Ar/CO 2 (70/30) with 5.9 keV X-rays; x- y resolution of σ=0.05 and 0.1 mm for top and bottom anode strips, respectively, and integral non-linearity of ˜0.15% are demonstrated.

  3. Two-dimensional convolver architecture for real-time image processing

    Science.gov (United States)

    Landeta, David; Malinowski, Chris W.

    1989-11-01

    This paper presents a novel architecture for two VLSI ICs, an 8-bit and 12-bit version, which execute real-time 3x3 kernel image convolutions at rates exceeding 10 ms per 512x512 pixel frame (at a 30 MHz external clock rate). The ICs are capable of performing "on-the-fly" convolutions of images without any need for external input image buffers. Both symmetric and asymmetric coefficient kernels are supported, with coefficient precision up to 12 bits. Nine on-chip multiplier-accumulators maintain double-precision accuracy for maximum precision of the results and minimum roundoff noise. In addition, an on-chip ALU can be switched into the pixel datapath to perform simultaneous pixel-point operations on the incoming data. Thus, operations such as thresholding, inversion, shifts, and double frame arithmetic can be performed on the pixels with no extra speed penalty. Flexible internal datapaths of the processors provide easy means for cascadability of several devices if larger image arrays need to be processed. Moreover, larger convolution kernels, such as 6x6, can easily be supported with no speed penalty by employing two or more convolvers. On-chip delay buffers can be programmed to any desired raster line width up to 1024 pixels. The delay buffers may also be bypassed when direct "Sum-Of-Products" operation of the multipliers is required; such as when external frame buffer address sequencing is desired. These features make the convolvers suitable for applications such as affine and bilinear interpolation, one-dimensional convolution (FIR filtration), and matrix operations. Several examples of applications illustrating stand-alone and cascade mode operation of the ICs will be discussed

  4. Two-dimensional biosensor arrays based on surface plasmon resonance phase imaging

    Science.gov (United States)

    Wong, C. L.; Ho, H. P.; Yu, T. T.; Suen, Y. K.; Chow, Winnie W. Y.; Wu, S. Y.; Law, W. C.; Yuan, W.; Li, W. J.; Kong, S. K.; Lin, Chinlon

    2007-04-01

    We present a biosensor design based on capturing the two-dimenstional (2D) phase image of surface plasmon resonance (SPR). This 2D SPR imaging technique may enable parallel label-free detection of multiple analytes and is compatible with the microarray chip platform. This system uses our previously reported differential phase measurement approach, in which 2D phase maps obtained from the signal (P) and reference (S) polarizations are compared pixel by pixel. This technique greatly improves detection resolution as the subtraction step can eliminate measurement fluctuations caused by external disturbances as they essentially appear in both channels. Unlike conventional angular SPR systems, in which illumination from a range of angles must be used, phase measurement requires illumination from only one angle, thus making it well suited for 2D measurement. Also, phase-stepping introduced from a moving mirror provides the necessary modulation for accurate detection of the phase. In light of the rapidly increasing need for fast real-time detection, quantification, and identification of a range of proteins for various biomedical applications, our 2D SPR phase imaging technique should hold a promising future in the medical device market.

  5. Two-dimensional orthogonal DCT expansion in trapezoid and triangular blocks and modified JPEG image compression.

    Science.gov (United States)

    Ding, Jian-Jiun; Huang, Ying-Wun; Lin, Pao-Yen; Pei, Soo-Chang; Chen, Hsin-Hui; Wang, Yu-Hsiang

    2013-09-01

    In the conventional JPEG algorithm, an image is divided into eight by eight blocks and then the 2-D DCT is applied to encode each block. In this paper, we find that, in addition to rectangular blocks, the 2-D DCT is also orthogonal in the trapezoid and triangular blocks. Therefore, instead of eight by eight blocks, we can generalize the JPEG algorithm and divide an image into trapezoid and triangular blocks according to the shapes of objects and achieve higher compression ratio. Compared with the existing shape adaptive compression algorithms, as we do not try to match the shape of each object exactly, the number of bytes used for encoding the edges can be less and the error caused from the high frequency component at the boundary can be avoided. The simulations show that, when the bit rate is fixed, our proposed algorithm can achieve higher PSNR than the JPEG algorithm and other shape adaptive algorithms. Furthermore, in addition to the 2-D DCT, we can also use our proposed method to generate the 2-D complete and orthogonal sine basis, Hartley basis, Walsh basis, and discrete polynomial basis in a trapezoid or a triangular block.

  6. Unsupervised skin lesions border detection via two-dimensional image analysis.

    Science.gov (United States)

    Abbas, Qaisar; Fondón, Irene; Rashid, Muhammad

    2011-12-01

    The skin cancer was analyzed by dermoscopy helpful for dermatologists. The classification of melanoma and carcinoma such as basal cell, squamous cell, and merkel cell carcinomas tumors can be increased the sensitivity and specificity. The detection of an automated border is an important step for the correctness of subsequent phases in the computerized melanoma recognition systems. The artifacts such as, dermoscopy-gel, specular reflection and outline (skin lines, blood vessels, and hair or ruler markings) were also contained in the dermoscopic images. In this paper, we present an unsupervised approach for multiple lesion segmentation, modification of Region-based Active Contours (RACs) as well as artifact diminution steps. Iterative thresholding is applied to initialize level set automatically; the stability of curves is enforced by maximum smoothing constraints on Courant-Friedreichs-Lewy (CFL) function. The work has been tested on dermoscopic database of 320 images. The border detection error is quantified by five distinct statistical metrics and manually used to determine the borders from a dermatologist as the ground truth. The segmentation results were compared with other state-of-the-art methods along with the evaluation criteria. The unsupervised border detection system increased the true detection rate (TDR) is 4.31% and reduced the false positive rate (FPR) of 5.28%.

  7. Two-dimensional TiS₂ nanosheets for in vivo photoacoustic imaging and photothermal cancer therapy.

    Science.gov (United States)

    Qian, Xiaoxin; Shen, Sida; Liu, Teng; Cheng, Liang; Liu, Zhuang

    2015-04-14

    Recently, transition metal dichalcogenides (TMDCs) have attracted significant attention in nanomedicine owing to their intriguing properties. In this study, TiS2 nanosheets, a new TMDC nanomaterial, are synthesized by a bottom-up solution-phase method and then modified with polyethylene glycol (PEG), obtaining TiS2-PEG with high stability in physiological solutions and no appreciable in vitro toxicity. Due to their high absorbance in the near-infrared (NIR) region, TiS2-PEG nanosheets could offer a strong contrast in photoacoustic imaging, which uncovers the high tumor uptake and retention of these nanosheets after systemic administration into tumor-bearing mice. We further apply TiS2-PEG nanosheets for in vivo photothermal therapy, which are able to completely eradicate the tumors in mice upon intravenous injection of TiS2-PEG followed by NIR laser irradiation. Our work indicates that TiS2 nanosheets with appropriate surface coating (e.g. PEGylation) would be a promising new class of photothermal agents for imaging-guided cancer therapy.

  8. Two-dimensional intraventricular flow pattern visualization using the image-based computational fluid dynamics.

    Science.gov (United States)

    Doost, Siamak N; Zhong, Liang; Su, Boyang; Morsi, Yosry S

    2016-10-31

    The image-based computational fluid dynamics (IB-CFD) technique, as the combination of medical images and the CFD method, is utilized in this research to analyze the left ventricle (LV) hemodynamics. The research primarily aims to propose a semi-automated technique utilizing some freely available and commercial software packages in order to simulate the LV hemodynamics using the IB-CFD technique. In this research, moreover, two different physiological time-resolved 2D models of a patient-specific LV with two different types of aortic and mitral valves, including the orifice-type valves and integrated with rigid leaflets, are adopted to visualize the process of developing intraventricular vortex formation and propagation. The blood flow pattern over the whole cardiac cycle of two models is also compared to investigate the effect of utilizing different valve types in the process of the intraventricular vortex formation. Numerical findings indicate that the model with integrated valves can predict more complex intraventricular flow that can match better the physiological flow pattern in comparison to the orifice-type model.

  9. A Method of Three-Dimensional Recording of Mandibular Movement Based on Two-Dimensional Image Feature Extraction.

    Directory of Open Access Journals (Sweden)

    Fusong Yuan

    Full Text Available To develop a real-time recording system based on computer binocular vision and two-dimensional image feature extraction to accurately record mandibular movement in three dimensions.A computer-based binocular vision device with two digital cameras was used in conjunction with a fixed head retention bracket to track occlusal movement. Software was developed for extracting target spatial coordinates in real time based on two-dimensional image feature recognition. A plaster model of a subject's upper and lower dentition were made using conventional methods. A mandibular occlusal splint was made on the plaster model, and then the occlusal surface was removed. Temporal denture base resin was used to make a 3-cm handle extending outside the mouth connecting the anterior labial surface of the occlusal splint with a detection target with intersecting lines designed for spatial coordinate extraction. The subject's head was firmly fixed in place, and the occlusal splint was fully seated on the mandibular dentition. The subject was then asked to make various mouth movements while the mandibular movement target locus point set was recorded. Comparisons between the coordinate values and the actual values of the 30 intersections on the detection target were then analyzed using paired t-tests.The three-dimensional trajectory curve shapes of the mandibular movements were consistent with the respective subject movements. Mean XYZ coordinate values and paired t-test results were as follows: X axis: -0.0037 ± 0.02953, P = 0.502; Y axis: 0.0037 ± 0.05242, P = 0.704; and Z axis: 0.0007 ± 0.06040, P = 0.952. The t-test result showed that the coordinate values of the 30 cross points were considered statistically no significant. (P<0.05.Use of a real-time recording system of three-dimensional mandibular movement based on computer binocular vision and two-dimensional image feature recognition technology produced a recording accuracy of approximately ± 0.1 mm, and is

  10. Two-dimensional solar spectropolarimetry with the KIS/IAA Visible Imaging Polarimeter

    Science.gov (United States)

    Beck, C.; Bellot Rubio, L. R.; Kentischer, T. J.; Tritschler, A.; Del Toro Iniesta, J. C.

    2010-09-01

    Context. Spectropolarimetry at high spatial and spectral resolution is a basic tool to characterize the magnetic properties of the solar atmosphere. Aims: We introduce the KIS/IAA Visible Imaging Polarimeter (VIP), a new post-focus instrument that upgrades the TESOS spectrometer at the German Vacuum Tower Telescope (VTT) into a full vector polarimeter. VIP is a collaboration between the Kiepenheuer Institut für Sonnenphysik (KIS) and the Instituto de Astrofísica de Andalucía (IAA-CSIC). Methods: We describe the optical setup of VIP, the data acquisition procedure, and the calibration of the spectropolarimetric measurements. We show examples of data taken between 2005 and 2008 to illustrate the potential of the instrument. Results: VIP is capable of measuring the four Stokes profiles of spectral lines in the range from 420 to 700 nm with a spatial resolution better than 0farcs5. Lines can be sampled at 40 wavelength positions in 60 s, achieving a noise level of about 2 × 10-3 with exposure times of 300 ms and pixel sizes of 0farcs17 × 0farcs17 (2 × 2 binning). The polarization modulation is stable over periods of a few days, ensuring high polarimetric accuracy. The excellent spectral resolution of TESOS allows the use of sophisticated data analysis techniques such as Stokes inversions. One of the first scientific results of VIP presented here is that the ribbon-like magnetic structures of the network are associated with a distinct pattern of net circular polarization away from disk center. Conclusions: VIP performs spectropolarimetric measurements of solar magnetic fields at a spatial resolution that is only slightly worse than that of the Hinode spectropolarimeter, while providing a 2D field field of view and the possibility to observe up to four spectral regions sequentially with high cadence. VIP can be used as a stand-alone instrument or in combination with other spectropolarimeters and imaging systems of the VTT for extended wavelength coverage.

  11. Symmetrical Two-Dimensional PCA with Image Measures in Face Recognition

    Directory of Open Access Journals (Sweden)

    Jicheng Meng

    2012-12-01

    Full Text Available In this paper, weextensively investigate symmetrical two‐dimensional principal component analysis (S2DPCA and introduce two image measures for S2DPCA‐based face recognition, volume measure (VM and subspace distance measure (SM. Although symmetrical features are an obviously but not absolutely facial characteristic, they have been successfully applied to PCA and 2DPCA. The paper gives detailed evidence that even and odd subspaces in S2DPCA are mutually orthogonal, and particularly that S2DPCA can be constructed using a quarter of the conventional S2DPCA even/odd covariance matrix. Based on these theories, we investigate the time and memory complexities of S2PDCA further, and find that S2DPCA can in fact be computed using a quarter of the time and memory compared to conventional S2DPCA. Finally, VM and SM are introduced to S2DPCA for final classification. Our experiments compare S2DPCA with 2DPCA on YALE, AR and FERET face databases, and the results indicate that S2DPCA+VM generally outperforms other algorithms.

  12. Two-dimensional solar spectropolarimetry with the KIS/IAA Visible Imaging Polarimeter

    CERN Document Server

    Beck, C; Kentischer, T J; Tritschler, A; Iniesta, J C del Toro

    2010-01-01

    Spectropolarimetry at high spatial and spectral resolution is a basic tool to characterize the magnetic properties of the solar atmosphere. We introduce the KIS/IAA Visible Imaging Polarimeter (VIP), a new post-focus instrument that upgrades the TESOS spectrometer at the German VTT into a full vector polarimeter. VIP is a collaboration between the KIS and the IAA. We describe the optical setup of VIP, the data acquisition procedure, and the calibration of the spectropolarimetric measurements. We show examples of data taken between 2005 and 2008 to illustrate the potential of the instrument. VIP is capable of measuring the four Stokes profiles of spectral lines in the range from 420 to 700 nm with a spatial resolution better than 0.5". Lines can be sampled at 40 wavelength positions in 60 s, achieving a noise level of about 2 x 10E-3 with exposure times of 300 ms and pixel sizes of 0.17" x 0.17" (2 x 2 binning). The polarization modulation is stable over periods of a few days, ensuring high polarimetric accura...

  13. Evaluation of left ventricular mechanical dyssynchrony in chronic heart failure patients by two-dimensional speckle tracking imaging.

    Science.gov (United States)

    Jiang, Feng-Xia; Guo, Rui-Qiang; Chen, Jin-Ling

    2013-07-01

    The purpose of this study was to evaluate left ventricular mechanical dyssynchrony (LVMD) in chronic heart failure (CHF) patients using two-dimensional speckle tracking imaging (2D-STI), and also to compare the usefulness of three patterns of myocardial deformation in mechanical dyssynchrony assessment. Furthermore, the relationships between left ventricular ejection fraction (LVEF), QRS duration (QRSd), and LVMD were explored. In total, 78 patients and 60 healthy individuals (group 3) were enrolled. The patients were classified into two subgroups: LVEF≤35% (group 1), 35%0.05). CHF patients have different extents of LVMD. Longitudinal deformation shows the best detectability of dyssynchrony motion. Left ventricular systolic function was closely related to mechanical dyssynchrony, whereas QRSd showed no significant correlation.

  14. Real-Time Time-Frequency Two-Dimensional Imaging of Ultrafast Transient Signals in Solid-State Organic Materials

    Directory of Open Access Journals (Sweden)

    Jun Takeda

    2010-04-01

    Full Text Available In this review, we demonstrate a real-time time-frequency two-dimensional (2D pump-probe imaging spectroscopy implemented on a single shot basis applicable to excited-state dynamics in solid-state organic and biological materials. Using this technique, we could successfully map ultrafast time-frequency 2D transient absorption signals of β-carotene in solid films with wide temporal and spectral ranges having very short accumulation time of 20 ms per unit frame. The results obtained indicate the high potential of this technique as a powerful and unique spectroscopic tool to observe ultrafast excited-state dynamics of organic and biological materials in solid-state, which undergo rapid photodegradation.

  15. Sensitivity of Deep-Towed Marine Electrical Resistivity Imaging Using Two-Dimensional Inversion: A Case Study on Methane Hydrate

    Directory of Open Access Journals (Sweden)

    Chih-Wen Chiang

    2012-01-01

    Full Text Available Uncertain physical properties of methane hydrate (MH above a bottom simulating reflector should be estimated for detecting MH-bearing formations. In contrast to general marine sediments, MH-bearing formations have a relatively high electrical resistivity. Therefore, marine electrical resistivity imaging (MERI is a well-suited method for MH exploration. The authors conducted sensitivity testing of sub-seafloor MH exploration using a two-dimensional (2D inversion algorithm with the Wenner, Pole-Dipole (PD and Dipole-Dipole (DD arrays. The results of the Wenner electrode array show the poorest resolution in comparison to the PD and DD arrays. The results of the study indicate that MERI is an effective geophysical method for exploring the sub-seafloor electrical structure and specifically for delineating resistive anomalies that may be present because of MH-bearing formations at a shallow depth beneath the seafloor.

  16. Compressive sensing based high-speed time-stretch optical microscopy for two-dimensional image acquisition.

    Science.gov (United States)

    Guo, Qiang; Chen, Hongwei; Weng, Zhiliang; Chen, Minghua; Yang, Sigang; Xie, Shizhong

    2015-11-16

    In this paper, compressive sensing based high-speed time-stretch optical microscopy for two-dimensional (2D) image acquisition is proposed and experimentally demonstrated for the first time. A section of dispersion compensating fiber (DCF) is used to perform wavelength-to-time conversion and then ultrafast spectral shaping of broadband optical pulses can be achieved via high-speed intensity modulation. A 2D spatial disperser comprising a pair of orthogonally oriented dispersers is employed to produce spatially structured illumination for 2D image acquisition and a section of single mode fiber (SMF) is utilized for pulse compression in the optical domain. In our scheme, a 1.2-GHz photodetector and a 50-MHz analog-to-digital converter (ADC) are used to acquire the energy of the compressed pulses. Image reconstructions are demonstrated at a frame rate of 500 kHz and a sixteen-fold image compression is achieved in our proof-of-concept demonstration.

  17. Gray-Scale Image Dehazing Guided by Scene Depth Information

    Directory of Open Access Journals (Sweden)

    Bo Jiang

    2016-01-01

    Full Text Available Combined with two different types of image dehazing strategies based on image enhancement and atmospheric physical model, respectively, a novel method for gray-scale image dehazing is proposed in this paper. For image-enhancement-based strategy, the characteristics of its simplicity, effectiveness, and no color distortion are preserved, and the common guided image filter is modified to match the application of image enhancement. Through wavelet decomposition, the high frequency boundary of original image is preserved in advance. Moreover, the process of image dehazing can be guided by the image of scene depth proportion directly estimated from the original gray-scale image. Our method has the advantages of brightness consistency and no distortion over the state-of-the-art methods based on atmospheric physical model. Particularly, our method overcomes the essential shortcoming of the abovementioned methods that are mainly working for color image. Meanwhile, an image of scene depth proportion is acquired as a byproduct of image dehazing.

  18. Gray tone image watermarking with complementary computer generated holography.

    Science.gov (United States)

    Martinez, Christophe; Laulagnet, Fabien; Lemonnier, Olivier

    2013-07-01

    We present herein an original approach for the watermarking of holograms in gray tone images for use in microscopic halftone image archiving. Our concept is based on the principle of complementary holography presented in a previous contribution. The efficiency of the concept is evaluated theoretically and experimentally. We demonstrate the interest of elliptical diffraction patterns as an alternative to the usual rectangular diffraction patterns and confirm the subsidiary role of the hologram amplitude in the hologram recovery process.

  19. Reconstruction of three-dimensional porous media from a single two-dimensional image using three-step sampling

    Science.gov (United States)

    Gao, MingLiang; He, XiaoHai; Teng, QiZhi; Zuo, Chen; Chen, DongDong

    2015-01-01

    A random three-dimensional (3D) porous medium can be reconstructed from a two-dimensional (2D) image by reconstructing an image from the original 2D image, and then repeatedly using the result to reconstruct the next 2D image. The reconstructed images are then stacked together to generate the entire reconstructed 3D porous medium. To perform this successfully, a very important issue must be addressed, i.e., controlling the continuity and variability among adjacent layers. Continuity and variability, which are consistent with the statistics characteristic of the training image (TI), ensure that the reconstructed result matches the TI. By selecting the number and location of the sampling points in the sampling process, the continuity and variability can be controlled directly, and thus the characteristics of the reconstructed image can be controlled indirectly. In this paper, we propose and develop an original sampling method called three-step sampling. In our sampling method, sampling points are extracted successively from the center of 5 ×5 and 3 ×3 sampling templates and the edge area based on a two-point correlation function. The continuity and variability of adjacent layers were considered during the three steps of the sampling process. Our method was tested on a Berea sandstone sample, and the reconstructed result was compared with the original sample, using tests involving porosity distribution, the lineal path function, the autocorrelation function, the pore and throat size distributions, and two-phase flow relative permeabilities. The comparison indicates that many statistical characteristics of the reconstructed result match with the TI and the reference 3D medium perfectly.

  20. Reconstruction of three-dimensional porous media from a single two-dimensional image using three-step sampling.

    Science.gov (United States)

    Gao, MingLiang; He, XiaoHai; Teng, QiZhi; Zuo, Chen; Chen, DongDong

    2015-01-01

    A random three-dimensional (3D) porous medium can be reconstructed from a two-dimensional (2D) image by reconstructing an image from the original 2D image, and then repeatedly using the result to reconstruct the next 2D image. The reconstructed images are then stacked together to generate the entire reconstructed 3D porous medium. To perform this successfully, a very important issue must be addressed, i.e., controlling the continuity and variability among adjacent layers. Continuity and variability, which are consistent with the statistics characteristic of the training image (TI), ensure that the reconstructed result matches the TI. By selecting the number and location of the sampling points in the sampling process, the continuity and variability can be controlled directly, and thus the characteristics of the reconstructed image can be controlled indirectly. In this paper, we propose and develop an original sampling method called three-step sampling. In our sampling method, sampling points are extracted successively from the center of 5×5 and 3×3 sampling templates and the edge area based on a two-point correlation function. The continuity and variability of adjacent layers were considered during the three steps of the sampling process. Our method was tested on a Berea sandstone sample, and the reconstructed result was compared with the original sample, using tests involving porosity distribution, the lineal path function, the autocorrelation function, the pore and throat size distributions, and two-phase flow relative permeabilities. The comparison indicates that many statistical characteristics of the reconstructed result match with the TI and the reference 3D medium perfectly.

  1. Incipient UV-Induced Structural Changes in Neutrophil Granulocytes: Morphometric and Texture Analysis of Two-Dimensional Digital Images.

    Science.gov (United States)

    Grbatinić, Ivan; Milošević, Nebojša T

    2016-04-01

    The aim of this study is to determine the ability and consequent significance of fractal and lacunarity analysis together with computational morphometric and gray-level co-occurrence matrix (GLCM) analysis in detecting subtle initial UVB-induced chromatin and cytosolic changes in neutrophil granulocytes. In addition, the direction and potential significance of the observed changes is speculated. Feulgen-stained neutrophils are pictured and their digitalized images are analyzed in specialized software for digital image processing and ImageJ analysis. Significant statistical difference is observed (p0.05). For other parameters there was mostly high statistical significance (p>0.05). Significant unmatched correlations were found as sensitive markers of early morphological changes in cells exposed to UV light. In addition, the correlation between nuclear area and entropy was determined and was highly significant (p<0.001). UVB light, due to its high absorbance by DNA molecules, leads to double behavior of the cells. On one hand, cells start to rearrange but on the other UV light starts very early to immediately damage the cell. All these processes are very subtle in their intensity and GLCM analysis and computational imaging methods based on fractal geometry, i.e. fractal and morphometric analysis, in particular their combination, are very sensitive for detecting and describing these early chromatin changes.

  2. Face Detection in Still Gray Images

    Science.gov (United States)

    2000-05-01

    statistical independence between the components. In our system we started with a manually de ned set of facial components and a simple geometrical...there was at least one detection with a higher SVM out- put value in its neighborhood. The neighborhood in the image plane was de ned as a 19 19 box...based classi er is shown in Fig. 16. A similar architecture was used for people detection [ Mohan 99]. On the rst level, component classi ers

  3. Needle path planning and steering in a three-dimensional non-static environment using two-dimensional ultrasound images

    Science.gov (United States)

    Vrooijink, Gustaaf J.; Abayazid, Momen; Patil, Sachin; Alterovitz, Ron; Misra, Sarthak

    2015-01-01

    Needle insertion is commonly performed in minimally invasive medical procedures such as biopsy and radiation cancer treatment. During such procedures, accurate needle tip placement is critical for correct diagnosis or successful treatment. Accurate placement of the needle tip inside tissue is challenging, especially when the target moves and anatomical obstacles must be avoided. We develop a needle steering system capable of autonomously and accurately guiding a steerable needle using two-dimensional (2D) ultrasound images. The needle is steered to a moving target while avoiding moving obstacles in a three-dimensional (3D) non-static environment. Using a 2D ultrasound imaging device, our system accurately tracks the needle tip motion in 3D space in order to estimate the tip pose. The needle tip pose is used by a rapidly exploring random tree-based motion planner to compute a feasible needle path to the target. The motion planner is sufficiently fast such that replanning can be performed repeatedly in a closed-loop manner. This enables the system to correct for perturbations in needle motion, and movement in obstacle and target locations. Our needle steering experiments in a soft-tissue phantom achieves maximum targeting errors of 0.86 ± 0.35 mm (without obstacles) and 2.16 ± 0.88 mm (with a moving obstacle). PMID:26279600

  4. a First Cryptosystem for Security of Two-Dimensional Data

    Science.gov (United States)

    Mishra, D. C.; Sharma, Himani; Sharma, R. K.; Kumar, Naveen

    In this paper, we present a novel technique for security of two-dimensional data with the help of cryptography and steganography. The presented approach provides multilayered security of two-dimensional data. First layer security was developed by cryptography and second layer by steganography. The advantage of steganography is that the intended secret message does not attract attention to itself as an object of scrutiny. This paper proposes a novel approach for encryption and decryption of information in the form of Word Data (.doc file), PDF document (.pdf file), Text document, Gray-scale images, and RGB images, etc. by using Vigenere Cipher (VC) associated with Discrete Fourier Transform (DFT) and then hiding the data behind the RGB image (i.e. steganography). Earlier developed techniques provide security of either PDF data, doc data, text data or image data, but not for all types of two-dimensional data and existing techniques used either cryptography or steganography for security. But proposed approach is suitable for all types of data and designed for security of information by cryptography and steganography. The experimental results for Word Data, PDF document, Text document, Gray-scale images and RGB images support the robustness and appropriateness for secure transmission of these data. The security analysis shows that the presented technique is immune from cryptanalytic. This technique further provides security while decryption as a check on behind which RGB color the information is hidden.

  5. Scanning Hall-probe microscopy system for two-dimensional imaging of critical current density in RE-123 coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Higashikawa, K., E-mail: kohei@super.ees.kyushu-u.ac.jp [Department of Electrical Engineering, Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Inoue, M.; Kawaguchi, T.; Shiohara, K.; Imamura, K.; Kiss, T. [Department of Electrical Engineering, Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Iijima, Y.; Kakimoto, K.; Saitoh, T. [Material Technology Laboratory, Fujikura, 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan); Izumi, T. [Superconductivity Research Laboratory, International Superconductivity Technology Center, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan)

    2011-11-15

    Nondestructive characterization method of in-plane distribution of critical current density for coated conductors. Current distribution in a coated conductor compared with that from theoretical analysis. Relationship between local critical current density and local magnetic field. We have developed a characterization method for two-dimensional imaging of critical current density in coated conductors (CCs) based on scanning Hall-probe microscopy (SHPM). The distributions of the magnetic field around a sample were measured for several different conditions of external magnetic fields, and then were converted to those of the sheet current density which flowed to shield the external magnetic field or to trap the penetrated magnetic field. As a result, it was found that the amplitude of the sheet current density corresponded to that of critical current density almost in all the area of the sample except for the region where current direction changed. This indicates that we could obtain an in-plane distribution of the critical current density with a spatial resolution of around 100 {mu}m in non-destructive manner by this method. We believe that this measurement will be a multifunctional and comprehensive characterization method for coated conductors.

  6. Differences in quantitative assessment of myocardial scar and gray zone by LGE-CMR imaging using established gray zone protocols.

    Science.gov (United States)

    Mesubi, Olurotimi; Ego-Osuala, Kelechi; Jeudy, Jean; Purtilo, James; Synowski, Stephen; Abutaleb, Ameer; Niekoop, Michelle; Abdulghani, Mohammed; Asoglu, Ramazan; See, Vincent; Saliaris, Anastasios; Shorofsky, Stephen; Dickfeld, Timm

    2015-02-01

    Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging is the gold standard for myocardial scar evaluation. Heterogeneous areas of scar ('gray zone'), may serve as arrhythmogenic substrate. Various gray zone protocols have been correlated to clinical outcomes and ventricular tachycardia channels. This study assessed the quantitative differences in gray zone and scar core sizes as defined by previously validated signal intensity (SI) threshold algorithms. High quality LGE-CMR images performed in 41 cardiomyopathy patients [ischemic (33) or non-ischemic (8)] were analyzed using previously validated SI threshold methods [Full Width at Half Maximum (FWHM), n-standard deviation (NSD) and modified-FWHM]. Myocardial scar was defined as scar core and gray zone using SI thresholds based on these methods. Scar core, gray zone and total scar sizes were then computed and compared among these models. The median gray zone mass was 2-3 times larger with FWHM (15 g, IQR: 8-26 g) compared to NSD or modified-FWHM (5 g, IQR: 3-9 g; and 8 g. IQR: 6-12 g respectively, p scar that was gray zone) also varied significantly among the three methods, 51 % (IQR: 42-61 %), 17 % (IQR: 11-21 %) versus 38 % (IQR: 33-43 %) for FWHM, NSD and modified-FWHM respectively (p scar core. Infarct core and total myocardial scar mass also differ using these methods. Further evaluation of the most accurate quantification method is needed.

  7. Characterization of the left atrial vortex flow by two-dimensional transesophageal contrast echocardiography using particle image velocimetry.

    Science.gov (United States)

    Park, Kyu-Hwan; Son, Jang-Won; Park, Won-Jong; Lee, Sang-Hee; Kim, Ung; Park, Jong-Seon; Shin, Dong-Gu; Kim, Young-Jo; Choi, Jung-Hyun; Houle, Helene; Vannan, Mani A; Hong, Geu-Ru

    2013-01-01

    This article is the first clinical investigation of the quantitative left atrial (LA) vortex flow by two-dimensional (2-D) transesophageal contrast echocardiography (2-D-TECE) using vector particle image velocimetry (PIV). The aims of this study were to assess the feasibility of LA vortex flow analysis and to characterize and quantify the LA vortex flow in controls and in patients with atrial fibrillation (AF). Thirty-five controls and 30 patients with AF underwent transesophageal contrast echocardiography. The velocity vector was estimated by particle image velocimetry. The morphology and pulsatility of the LA vortex flow were compared between the control and AF groups. In all patients, quantitative LA vortex flow analysis was feasible. In the control group, multiple, pulsatile, compact and elliptical-shaped vortices were seen in the periphery of the LA. These vortices were persistently maintained and vectors were directed toward the atrioventricular inflow. In the AF group, a large, merged, lower pulsatile and round-shaped vortex was observed in the center of the LA. In comparisons of vortex parameters, the relative strength was significantly lower in the AF group (1.624 ± 0.501 vs. 2.105 ± 0.226, p < 0.001). It is feasible to characterize and quantify the LA vortex flow by transesophageal contrast echocardiography in patients with AF, which offers a new method to obtain additional information on LA hemodynamics. The approach has the potential for early detection of the LA dysfunction and in decisions regarding treatment strategy and guiding anticoagulation treatment in patients with AF.

  8. Extended gray level co-occurrence matrix computation for 3D image volume

    Science.gov (United States)

    Salih, Nurulazirah M.; Dewi, Dyah Ekashanti Octorina

    2017-02-01

    Gray Level Co-occurrence Matrix (GLCM) is one of the main techniques for texture analysis that has been widely used in many applications. Conventional GLCMs usually focus on two-dimensional (2D) image texture analysis only. However, a three-dimensional (3D) image volume requires specific texture analysis computation. In this paper, an extended 2D to 3D GLCM approach based on the concept of multiple 2D plane positions and pixel orientation directions in the 3D environment is proposed. The algorithm was implemented by breaking down the 3D image volume into 2D slices based on five different plane positions (coordinate axes and oblique axes) resulting in 13 independent directions, then calculating the GLCMs. The resulted GLCMs were averaged to obtain normalized values, then the 3D texture features were calculated. A preliminary examination was performed on a 3D image volume (64 x 64 x 64 voxels). Our analysis confirmed that the proposed technique is capable of extracting the 3D texture features from the extended GLCMs approach. It is a simple and comprehensive technique that can contribute to the 3D image analysis.

  9. Two-Dimensional Image Fusion of Planar Bone Scintigraphy and Radiographs in Patients with Clinical Scaphoid Fracture: An Imaging Study

    DEFF Research Database (Denmark)

    Henriksen, O.M.; Lonsdale, M.N.; Jensen, T.D.

    2008-01-01

    experienced nuclear medicine physicians. In addition to the diagnosis, the degree of diagnostic confidence was scored in each case. Results: The addition of fusion images changed the interpretation of each of the three observers in seven, four, and two cases, respectively, reducing the number of positive....... Bone scintigraphy is highly sensitive for the detection of fractures, but exact localization of scintigraphic lesions may be difficult and can negatively affect diagnostic accuracy. Purpose: To investigate the influence of image fusion of planar bone scintigraphy and radiographs on image interpretation...... in patients with suspected scaphoid fracture. Material and Methods: In 24 consecutive patients with suspected scaphoid fracture, a standard planar bone scintigraphy of both hands was supplemented with fusion imaging of the injured wrist. Standard and fusion images were evaluated independently by three...

  10. Two-dimensional fusion imaging of planar bone scintigraphy and radiographs in patients with clinical scaphoid fracture: an imaging study

    DEFF Research Database (Denmark)

    Henriksen, Otto Mølby; Lonsdale, Markus Georg; Jensen, T D

    2009-01-01

    experienced nuclear medicine physicians. In addition to the diagnosis, the degree of diagnostic confidence was scored in each case. RESULTS: The addition of fusion images changed the interpretation of each of the three observers in seven, four, and two cases, respectively, reducing the number of positive....... Bone scintigraphy is highly sensitive for the detection of fractures, but exact localization of scintigraphic lesions may be difficult and can negatively affect diagnostic accuracy. PURPOSE: To investigate the influence of image fusion of planar bone scintigraphy and radiographs on image interpretation...... in patients with suspected scaphoid fracture. MATERIAL AND METHODS: In 24 consecutive patients with suspected scaphoid fracture, a standard planar bone scintigraphy of both hands was supplemented with fusion imaging of the injured wrist. Standard and fusion images were evaluated independently by three...

  11. Two-Dimensional Image Fusion of Planar Bone Scintigraphy and Radiographs in Patients with Clinical Scaphoid Fracture: An Imaging Study

    DEFF Research Database (Denmark)

    Henriksen, O.M.; Lonsdale, M.N.; Jensen, T.D.

    2008-01-01

    experienced nuclear medicine physicians. In addition to the diagnosis, the degree of diagnostic confidence was scored in each case. Results: The addition of fusion images changed the interpretation of each of the three observers in seven, four, and two cases, respectively, reducing the number of positive....... Bone scintigraphy is highly sensitive for the detection of fractures, but exact localization of scintigraphic lesions may be difficult and can negatively affect diagnostic accuracy. Purpose: To investigate the influence of image fusion of planar bone scintigraphy and radiographs on image interpretation...... in patients with suspected scaphoid fracture. Material and Methods: In 24 consecutive patients with suspected scaphoid fracture, a standard planar bone scintigraphy of both hands was supplemented with fusion imaging of the injured wrist. Standard and fusion images were evaluated independently by three...

  12. Two-Dimensional Image Fusion of Planar Bone Scintigraphy and Radiographs in Patients with Clinical Scaphoid Fracture: An Imaging Study

    Energy Technology Data Exchange (ETDEWEB)

    Henriksen, O.M.; Lonsdale, M.N.; Jensen, T.D.; Weikop, K.L.; Holm, O.; Duus, B.; Friberg, L. (Dept. of Clinical Physiology/Nuclear Medicine, Glostrup Hospital, Glostrup (Denmark))

    2009-01-15

    Background: Although magnetic resonance imaging (MRI) is now considered the gold standard in second-line imaging of patients with suspected scaphoid fracture and negative radiographs, bone scintigraphy can be used in patients with pacemakers, metallic implants, or other contraindications to MRI. Bone scintigraphy is highly sensitive for the detection of fractures, but exact localization of scintigraphic lesions may be difficult and can negatively affect diagnostic accuracy. Purpose: To investigate the influence of image fusion of planar bone scintigraphy and radiographs on image interpretation in patients with suspected scaphoid fracture. Material and Methods: In 24 consecutive patients with suspected scaphoid fracture, a standard planar bone scintigraphy of both hands was supplemented with fusion imaging of the injured wrist. Standard and fusion images were evaluated independently by three experienced nuclear medicine physicians. In addition to the diagnosis, the degree of diagnostic confidence was scored in each case. Results: The addition of fusion images changed the interpretation of each of the three observers in seven, four, and two cases, respectively, reducing the number of positive interpretations of two of the observers from 11 and nine cases to six and seven cases, respectively. The degree of diagnostic confidence increased significantly in two observers, and interobserver agreement increased in all three pairs of observers from 0.83, 0.57, and 0.73 to 0.89, 0.8, and 0.9, respectively. Conclusion: Image fusion of planar bone scintigrams and radiographs has a significant influence on image interpretation and increases both diagnostic confidence and interobserver agreement

  13. Diagnosis of pathological conditions of kidney by two-dimensional and three-dimensional ultrasonographic imaging in dogs

    Directory of Open Access Journals (Sweden)

    Dinesh Dehmiwal

    2016-07-01

    Full Text Available Aim: The objective of the study was to obtain and compare two-dimensional (2D and three-dimensional (3D ultrasonographic images of the kidney in different disease conditions. Materials and Methods: In this study, 11 clinical cases of different age groups of dogs suffering from kidney diseases were diagnosed by 2D and 3D ultrasonography at Teaching Veterinary Clinical Complex, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar. The ultrasound (US machine used for this study was 3D US machine (Nemio-XG: Toshiba, Japan having four-dimensional (4D volumetric probe. The images were acquired with 3-6 MHz 2D curvilinear transducer and 4.2-6 MHz 4D volumetric curvilinear transducer. Results: Nephritis was diagnosed in four dogs aged between 5 months and 6 years. In all the cases of nephritis diffuse increase in echogenicity of kidney, parenchyma was observed. Two dogs with end-stage kidney disease were also diagnosed. In both 2D and 3D ultrasonography, the kidney size was decreased and architectural details were also lost in them. The cases of regional renal diseases diagnosed were hydronephrosis and nephrolithiasis. Dilated renal pelvis was the common finding in all the three cases of hydronephrosis in both 2D and 3D ultrasonogram. Nephroliths were observed in one case with the history of hematuria and oliguria. The multifocal renal disease diagnosed in this study was dysplastic polycystic kidney. In 2D ultrasonogram, six anechoic cavities appeared with thin strip of renal parenchyma. In 3D ultrasonogram, the cysts appeared as black anechoic areas. Conclusion: The result of the current study showed that the clinical conditions of kidney such as nephritis, end-stage kidney, hydronephrosis, polycystic kidney, and nephrolithiasis can be diagnosed easily using 2D and 3D ultrasonography. Visualization of renal structures was clear in 2D ultrasonography in the conditions of nephritis and end-stage kidney. However, the conditions such as

  14. Two-dimensional Co-Seismic Surface Displacements Field of the Chi-Chi Earthquake Inferred from SAR Image Matching

    Science.gov (United States)

    Hu, Jun; Li, Zhi-Wei; Ding, Xiao-Li; Zhu, Jian-Jun

    2008-01-01

    The Mw=7.6 Chi-Chi earthquake in Taiwan occurred in 1999 over the Chelungpu fault and caused a great surface rupture and severe damage. Differential Synthetic Aperture Radar Interferometry (DInSAR) has been applied previously to study the co-seismic ground displacements. There have however been significant limitations in the studies. First, only one-dimensional displacements along the Line-of-Sight (LOS) direction have been measured. The large horizontal displacements along the Chelungpu fault are largely missing from the measurements as the fault is nearly perpendicular to the LOS direction. Second, due to severe signal decorrelation on the hangling wall of the fault, the displacements in that area are un-measurable by differential InSAR method. We estimate the co-seismic displacements in both the azimuth and range directions with the method of SAR amplitude image matching. GPS observations at the 10 GPS stations are used to correct for the orbital ramp in the amplitude matching and to create the two-dimensional (2D) co-seismic surface displacements field using the descending ERS-2 SAR image pair. The results show that the co-seismic displacements range from about -2.0 m to 0.7 m in the azimuth direction (with the positive direction pointing to the flight direction), with the footwall side of the fault moving mainly southwards and the hanging wall side northwards. The displacements in the LOS direction range from about -0.5 m to 1.0 m, with the largest displacement occuring in the northeastern part of the hanging wall (the positive direction points to the satellite from ground). Comparing the results from amplitude matching with those from DInSAR, we can see that while only a very small fraction of the LOS displacement has been recovered by the DInSAR mehtod, the azimuth displacements cannot be well detected with the DInSAR measurements as they are almost perpendicular to the LOS. Therefore, the amplitude matching method is obviously more advantageous than the DIn

  15. Digital Slot Radiography Based On A Linear X-Ray Image Intensifier And Two-Dimensional Image Sensors.

    Science.gov (United States)

    Beerlage, M. J. M.; Levels, H. P. L.; Mulder, H.

    1986-06-01

    Apart from providing the inherent benefits of digital imaging, a digital chest system should preferably be superior to large-size film with respect to diagnostic quality. Systems, demonstrated until now, tend to fail in that respect. Here we describe a system -under development- that combines the advantages of film (e.g. high resolution), area detectors (wide sensor dynamic range) and slit detectors (efficient reduction of scattered radiation, high contrast resolution and instantaneous image availibility). Thereby the system is low-dose, compact and operating at standard X-ray tube loading.

  16. Recovering root system traits using image analysis exemplified by two-dimensional neutron radiography images of lupine.

    Science.gov (United States)

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

    2014-01-01

    Root system traits are important in view of current challenges such as sustainable crop production with reduced fertilizer input or in resource-limited environments. We present a novel approach for recovering root architectural parameters based on image-analysis techniques. It is based on a graph representation of the segmented and skeletonized image of the root system, where individual roots are tracked in a fully automated way. Using a dynamic root architecture model for deciding whether a specific path in the graph is likely to represent a root helps to distinguish root overlaps from branches and favors the analysis of root development over a sequence of images. After the root tracking step, global traits such as topological characteristics as well as root architectural parameters are computed. Analysis of neutron radiographic root system images of lupine (Lupinus albus) grown in mesocosms filled with sandy soil results in a set of root architectural parameters. They are used to simulate the dynamic development of the root system and to compute the corresponding root length densities in the mesocosm. The graph representation of the root system provides global information about connectivity inside the graph. The underlying root growth model helps to determine which path inside the graph is most likely for a given root. This facilitates the systematic investigation of root architectural traits, in particular with respect to the parameterization of dynamic root architecture models.

  17. Electrowetting on dielectric digital microfluidic platform with nanostructured biosensor interface for enhanced two-dimensional surface plasmon resonance imaging detection

    Science.gov (United States)

    Malic, Lidija

    The sensitive and specific detection of biomolecular interactions is at the heart of many routine analyses in fundamental research, medical diagnosis and environmental monitoring. In contrast to laborious and costly multiwell plate assays, recent years have witnessed a significant progress in miniaturized and integrated biosensors, such as surface plasmon resonance (SPR), tailored to these applications. While the design of various SPR biosensors has been described in literature, a robust, multichannel, low-cost and highly sensitive solution has not yet been presented. Specifically, an integrated system that can allow surface functionalization in array format, low-volume multichannel fluidic interfacing, and increased sensitivity is sought. This thesis describes a novel electro-wetting-on-dielectric (EWOD) digital microfluidic device with integrated nanostructured biosensor interface that addresses the aforementioned issues for enhanced surface plasmon resonance imaging (SPRi) detection. We have taken the opportunity of the most recent advances in microfabrication, nanotechnology and SPR technique to develop this integrated platform. EWOD device is employed for the dynamic immobilization of bioreceptors on SPRi biosensor surface in an array fashion from sub-muL volume solutions. Programmable EWOD electric interface allows the application of an electric field at the biosensor surface for active control of the immobilized probe density and orientation, enhancing SPRi detection. Two-dimensional SPRi detection is achieved by coupling the EWOD device to SPRi instrumentation. Parallel manipulation of individual droplets allows more efficient exploitation of the biosensor surface by separating different samples for simultaneous and selective SPRi detection. Periodic gold structures (nanoposts, nanogratings and nanogrooves) residing on a surface of glass and plastic substrates are investigated to improve the SPRi sensitivity. The corresponding electromagnetic field

  18. The feasibility and application of gray scale adjustment method in high temperature digital image correlation

    Science.gov (United States)

    Wang, Shen; Yao, Xue Feng; Su, Yun Quan; Liu, Wei

    2017-02-01

    In this paper, the basic principle and application of linear gray scale adjustment method are investigated in high temperature digital image correlation (DIC) technology. First, the simple linear gray scale adjustment method is proposed, which can adjust the gray scale value of the saturated pixels and diminish the correlation error caused by the saturated pixels. Then, both the simulated high temperature images and DIC correlation results before and after the gray scale adjustment are provided and analyzed to verify its effectiveness, in which the displacement error decreased from 0.1 pixels to 0.04 pixels after the linear gray scale adjustment for high temperature images. Finally, the linear gray scale adjustment method is used to extract the displacement with high accuracy in high temperature experiment of SiC specimen, and the displacement error decreased from 0.5 pixels to 0.1 pixels after the linear gray scale adjustment.

  19. Two-dimensional and three-dimensional dynamic imaging of live biofilms in a microchannel by time-of-flight secondary ion mass spectrometry.

    Science.gov (United States)

    Hua, Xin; Marshall, Matthew J; Xiong, Yijia; Ma, Xiang; Zhou, Yufan; Tucker, Abigail E; Zhu, Zihua; Liu, Songqin; Yu, Xiao-Ying

    2015-05-01

    A vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface), was employed for in situ chemical imaging of live biofilms using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling by sputtering materials in sequential layers resulted in live biofilm spatial chemical mapping. Two-dimensional (2D) images were reconstructed to report the first three-dimensional images of hydrated biofilm elucidating spatial and chemical heterogeneity. 2D image principal component analysis was conducted among biofilms at different locations in the microchannel. Our approach directly visualized spatial and chemical heterogeneity within the living biofilm by dynamic liquid ToF-SIMS.

  20. Two-dimensional Co-Seismic Surface Displacements Field of the Chi-Chi Earthquake Inferred from SAR Image Matching

    Directory of Open Access Journals (Sweden)

    Jian-Jun Zhu

    2008-10-01

    Full Text Available The Mw=7.6 Chi-Chi earthquake in Taiwan occurred in 1999 over the Chelungpu fault and caused a great surface rupture and severe damage. Differential Synthetic Aperture Radar Interferometry (DInSAR has been applied previously to study the co-seismic ground displacements. There have however been significant limitations in the studies. First, only one-dimensional displacements along the Line-of-Sight (LOS direction have been measured. The large horizontal displacements along the Chelungpu fault are largely missing from the measurements as the fault is nearly perpendicular to the LOS direction. Second, due to severe signal decorrelation on the hangling wall of the fault, the displacements in that area are un-measurable by differential InSAR method. We estimate the co-seismic displacements in both the azimuth and range directions with the method of SAR amplitude image matching. GPS observations at the 10 GPS stations are used to correct for the orbital ramp in the amplitude matching and to create the two-dimensional (2D co-seismic surface displacements field using the descending ERS-2 SAR image pair. The results show that the co-seismic displacements range from about -2.0 m to 0.7 m in the azimuth direction (with the positive direction pointing to the flight direction, with the footwall side of the fault moving mainly southwards and the hanging wall side northwards. The displacements in the LOS direction range from about -0.5 m to 1.0 m, with the largest displacement occuring in the northeastern part of the hanging wall (the positive direction points to the satellite from ground. Comparing the results from amplitude matching with those from DInSAR, we can see that while only a very small fraction of the LOS displacement has been recovered by the DInSAR mehtod, the azimuth displacements cannot be well detected with the DInSAR measurements as they are almost perpendicular to the LOS. Therefore, the amplitude matching method is obviously more

  1. A study to evaluate the reliability of using two-dimensional photographs, three-dimensional images, and stereoscopic projected three-dimensional images for patient assessment.

    Science.gov (United States)

    Zhu, S; Yang, Y; Khambay, B

    2017-03-01

    Clinicians are accustomed to viewing conventional two-dimensional (2D) photographs and assume that viewing three-dimensional (3D) images is similar. Facial images captured in 3D are not viewed in true 3D; this may alter clinical judgement. The aim of this study was to evaluate the reliability of using conventional photographs, 3D images, and stereoscopic projected 3D images to rate the severity of the deformity in pre-surgical class III patients. Forty adult patients were recruited. Eight raters assessed facial height, symmetry, and profile using the three different viewing media and a 100-mm visual analogue scale (VAS), and appraised the most informative viewing medium. Inter-rater consistency was above good for all three media. Intra-rater reliability was not significantly different for rating facial height using 2D (P=0.704), symmetry using 3D (P=0.056), and profile using projected 3D (P=0.749). Using projected 3D for rating profile and symmetry resulted in significantly lower median VAS scores than either 3D or 2D images (all Pstereoscopic 3D projection was the preferred method for rating. The reliability of assessing specific characteristics was dependent on the viewing medium. Clinicians should be aware that the visual information provided when viewing 3D images is not the same as when viewing 2D photographs, especially for facial depth, and this may change the clinical impression.

  2. Two-dimensional multi-frequency imaging of a tumor inclusion in a homogeneous breast phantom using the harmonic motion Doppler imaging method

    Science.gov (United States)

    Kamali Tafreshi, Azadeh; Barış Top, Can; Güneri Gençer, Nevzat

    2017-06-01

    Harmonic motion microwave Doppler imaging (HMMDI) is a novel imaging modality for imaging the coupled electrical and mechanical properties of body tissues. In this paper, we used two experimental systems with different receiver configurations to obtain HMMDI images from tissue-mimicking phantoms at multiple vibration frequencies between 15 Hz and 35 Hz. In the first system, we used a spectrum analyzer to obtain the Doppler data in the frequency domain, while in the second one, we used a homodyne receiver that was designed to acquire time-domain data. The developed phantoms mimicked the elastic and dielectric properties of breast fat tissue, and included a 14~\\text{mm}× 9 mm cylindrical inclusion representing the tumor. A focused ultrasound probe was mechanically scanned in two lateral dimensions to obtain two-dimensional HMMDI images of the phantoms. The inclusions were resolved inside the fat phantom using both experimental setups. The image resolution increased with increasing vibration frequency. The designed receiver showed higher sensitivity than the spectrum analyzer measurements. The results also showed that time-domain data acquisition should be used to fully exploit the potential of the HMMDI method.

  3. Range imaging pulsed laser sensor with two-dimensional scanning of transmitted beam and scanless receiver using high-aspect avalanche photodiode array for eye-safe wavelength

    Science.gov (United States)

    Tsuji, Hidenobu; Imaki, Masaharu; Kotake, Nobuki; Hirai, Akihito; Nakaji, Masaharu; Kameyama, Shumpei

    2017-03-01

    We demonstrate a range imaging pulsed laser sensor with two-dimensional scanning of a transmitted beam and a scanless receiver using a high-aspect avalanche photodiode (APD) array for the eye-safe wavelength. The system achieves a high frame rate and long-range imaging with a relatively simple sensor configuration. We developed a high-aspect APD array for the wavelength of 1.5 μm, a receiver integrated circuit, and a range and intensity detector. By combining these devices, we realized 160×120 pixels range imaging with a frame rate of 8 Hz at a distance of about 50 m.

  4. The retrieval of two-dimensional distribution of the earth's surface aerodynamic roughness using SAR image and TM thermal infrared image

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Renhua; WANG; Jinfeng; ZHU; Caiying; SUN; Xiaomin

    2004-01-01

    After having analyzed the requirement on the aerodynamic earth's surface roughness in two-dimensional distribution in the research field of interaction between land surface and atmosphere, this paper presents a new way to calculate the aerodynamic roughness using the earth's surface geometric roughness retrieved from SAR (Synthetic Aperture Radar) and TM thermal infrared image data. On the one hand, the SPM (Small Perturbation Model) was used as a theoretical SAR backscattering model to describe the relationship between the SAR backscattering coefficient and the earth's surface geometric roughness and its dielectric constant retrieved from the physical model between the soil thermal inertia and the soil surface moisture with the simultaneous TM thermal infrared image data and the ground microclimate data. On the basis of the SAR image matching with the TM image, the non-volume scattering surface geometric information was obtained from the SPM model at the TM image pixel scale, and the ground pixel surface's equivalent geometric roughness-height standard RMS (Root Mean Square) was achieved from the geometric information by the transformation of the typical topographic factors. The vegetation (wheat, tree) height retrieved from spectrum model was also transferred into its equivalent geometric roughness. A completely two-dimensional distribution map of the equivalent geometric roughness over the experimental area was produced by the data mosaic technique. On the other hand, according to the atmospheric eddy currents theory, the aerodynamic surface roughness was iterated out with the atmosphere stability correction method using the wind and the temperature profiles data measured at several typical fields such as bare soil field and vegetation field. After having analyzed the effect of surface equivalent geometric roughness together with dynamic and thermodynamic factors on the aerodynamic surface roughness within the working area, this paper first establishes a scale

  5. A gray-natural logarithm ratio bilateral filtering method for image processing

    Institute of Scientific and Technical Information of China (English)

    Guanan Chen; Kuntao Yang; Rong Chen; Zhiming Xie

    2008-01-01

    A new method based on gray-natural logarithm ratio bilateral filtering is presented for image smoothing in this work. A new gray-natural logarithm ratio range filter kernel, leading to adaptive magnitude from image gray distinction information, is pointed out for the bilateral filtering. The new method can not only well restrain noise but also keep much more weak edges and details of an image, and preserve the original color transition of color images. Experimental results show the effectiveness for image denoising with our method.

  6. Non-contrast-enhanced hepatic MR angiography: Do two-dimensional parallel imaging and short tau inversion recovery methods shorten acquisition time without image quality deterioration?

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Kotaro, E-mail: kotaro@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Isoda, Hiroyoshi, E-mail: sayuki@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Okada, Tomohisa, E-mail: tomokada@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Kamae, Toshikazu, E-mail: toshi13@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Arizono, Shigeki, E-mail: arizono@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Hirokawa, Yuusuke, E-mail: yuusuke@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Shibata, Toshiya, E-mail: ksj@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Togashi, Kaori, E-mail: ktogashi@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)

    2011-01-15

    Objective: To study whether shortening the acquisition time for selective hepatic artery visualization is feasible without image quality deterioration by adopting two-dimensional (2D) parallel imaging (PI) and short tau inversion recovery (STIR) methods. Materials and methods: Twenty-four healthy volunteers were enrolled. 3D true steady-state free-precession imaging with a time spatial labeling inversion pulse was conducted using 1D or 2D-PI and fat suppression by chemical shift selective (CHESS) or STIR methods. Three groups of different scan conditions were assigned and compared: group A (1D-PI factor 2 and CHESS), group B (2D-PI factor 2 x 2 and CHESS), and group C (2D-PI factor 2 x 2 and STIR). The artery-to-liver contrast was quantified, and the quality of artery visualization and overall image quality were scored. Results: The mean scan time was 9.5 {+-} 1.0 min (mean {+-} standard deviation), 5.9 {+-} 0.8 min, and 5.8 {+-} 0.5 min in groups A, B, and C, respectively, and was significantly shorter in groups B and C than in group A (P < 0.01). The artery-to-liver contrast was significantly better in group C than in groups A and B (P < 0.01). The scores for artery visualization and overall image quality were worse in group B than in groups A and C. The differences were statistically significant (P < 0.05) regarding the arterial branches of segments 4 and 8. Between group A and group C, which had similar scores, there were no statistically significant differences. Conclusion: Shortening the acquisition time for selective hepatic artery visualization was feasible without deterioration of the image quality by the combination of 2D-PI and STIR methods. It will facilitate using non-contrast-enhanced MRA in clinical practice.

  7. Enhancing FTIR imaging capabilities with two-dimensional correlation spectroscopy (2DCOS): A study of concentration gradients of collagen and proteoglycans in human patellar cartilage

    Science.gov (United States)

    Jiang, Eric Y.; Rieppo, Jarno

    2006-11-01

    This paper explores a new application of two-dimensional correlation spectroscopy (2DCOS) in FTIR spectroscopic imaging analysis of biological samples. A particular example demonstrated in this paper is the characterization of concentration gradients of collagen and proteoglycans in human patellar cartilage. A focal plane array detector-based FTIR imaging system has been proven to be an efficient tool to detect early collagen and proteoglycans degradation in developing osteoarthrosis through evaluating compositional changes of osteoarthritic cartilage along the depth. However, the closely overlapped bands of collagen and proteoglycans make normal spectral and spatial analysis difficult. With 2DCOS analysis of the imaging data, it is possible to enhance the spectral resolution and reveal distinctive compositional changes that are normally hidden with conventional approaches. The combined technique, FTIR imaging enhanced with 2DCOS, provides new possibilities to solve challenging problems in the analysis of complex biological systems.

  8. Modified Dynamic Histogram Equalization For Image Enhancement in Gray-scale Images

    Directory of Open Access Journals (Sweden)

    R.M. Meenal

    2012-12-01

    Full Text Available To improve the quality of digital images captured in low light environment from consumer electronics devices like cell phone cameras, Modified Dynamic Histogram Equalization (MDHE is proposed. Initially, the proposed method divides the histogram into two sub-histograms based on median. Then 2nd subhistogram is further divided into two sub-histograms based on median of it. The resultant sub-histograms are clipped according to the mean of the intensity occurrence of the input image independently. The new dynamic range is allocated to each sub-histogram. The first sub-histogram is equalized independently using Global Histogram Equalization (GHE method. GHE is found the better enhancement for lower gray-levels and suffers over-enhancement problem in higher gray-level. The proposed method utilizes the advantages of both GHE and QDHE. This method utilizes GHE for enhancing lower gray-levels and QDHE for enhancing higher gray-levels. Simulation results show that the proposed method yields better quality images in terms of Discrete Entropy value compared with other conventional methods.

  9. Two-dimensional power Doppler-three-dimensional ultrasound imaging of a cesarean section dehiscence with utero-peritoneal fistula: a case report

    Directory of Open Access Journals (Sweden)

    Royo Pedro

    2009-01-01

    Full Text Available Abstract Introduction An imaging diagnosis after an iterative cesarean delivery is reviewed demonstrating a fine ultrasound-pathologic correlation. Case presentation A 33-year-old woman (G3, P3 presented referring intense dysmenorrhea and intermenstrual spotting since her third cesarean delivery, 1 year before. A cesarean section dehiscence with utero-peritoneal fistula was diagnosed by transvaginal ultrasound. Conclusion We can conclude that transvaginal two-dimensional power Doppler and three-dimensional ultrasound are highly accurate in detecting cesarean section dehiscence and uterine fistula.

  10. Myocardial Damage Detected by Two-Dimensional Speckle-Tracking Echocardiography in Patients with Extracardiac Sarcoidosis: Comparison with Magnetic Resonance Imaging.

    Science.gov (United States)

    Orii, Makoto; Hirata, Kumiko; Tanimoto, Takashi; Shiono, Yasutsugu; Shimamura, Kunihiro; Yamano, Takashi; Ino, Yasushi; Yamaguchi, Tomoyuki; Kubo, Takashi; Tanaka, Atsushi; Imanishi, Toshio; Akasaka, Takashi

    2015-06-01

    The aim of this study was to determine whether two-dimensional speckle-tracking echocardiography can identify the myocardial damage detected by delayed enhancement (DE) magnetic resonance imaging via the differences in myocardial deformation in patients with extracardiac sarcoidosis who showed no structural and functional abnormalities in the heart. Forty-five patients with biopsy-proven extracardiac sarcoidosis were analyzed retrospectively. Patients with abnormal electrocardiographic and echocardiographic findings, including ventricular arrhythmias, heart block, regional wall motion abnormalities, valvular heart disease, and cardiomyopathy, were excluded. Ten age-matched healthy control subjects were recruited as a control group. Comprehensive echocardiography and DE magnetic resonance imaging were performed, and circumferential, longitudinal, and radial strain were consecutively assessed using two-dimensional speckle-tracking echocardiographic software in a 16-segment model of the left ventricle in accordance to the presence (DE+) or absence (DE-) of DE. Among the 45 patients, 36 segments in 13 patients showed DE. DE+ segments had lower peak circumferential strain than DE- and control segments (-14 ± 5% vs -28 ± 7% vs -30 ± 7%, P speckle-tracking echocardiography can identify the myocardial damage detected by DE magnetic resonance imaging in patients with extracardiac sarcoidosis. Copyright © 2015 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

  11. The differences in left atrial function between ischemic and idiopathic dilated cardiomyopathy patients: A two-dimensional speckle tracking imaging study.

    Science.gov (United States)

    Cao, Sheng; Zhou, Qing; Chen, Jin-Ling; Hu, Bo; Guo, Rui-Qiang

    2016-09-01

    To evaluate left atrial (LA) function in patients with ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy via two-dimensional speckle-tracking imaging. We measured the LA maximum volume, minimum volume, and volume before the atrial systole, and calculated total emptying volume, expansion index, active emptying volume, and fraction. We measured strain and strain rate during systole and late diastole using two-dimensional speckle-tracking imaging, and analyzed correlations between variables. We found no significant differences in LA size, left ventricle (LV) end-diastole diameter, LV ejection fraction (EF), E/A, E/e', deceleration time of the E wave, and effective mitral regurgitant orifice area between the DCM and the ICM group. However, the LA expansion index, active EF, systolic and late diastolic strain, and strain rate were lower in the ICM group (p speckle-tracking imaging is a promising method to differentiate these patients. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:437-445, 2016. © 2016 Wiley Periodicals, Inc.

  12. Two-Dimensional Sectioned Images and Three-Dimensional Surface Models for Learning the Anatomy of the Female Pelvis

    Science.gov (United States)

    Shin, Dong Sun; Jang, Hae Gwon; Hwang, Sung Bae; Har, Dong-Hwan; Moon, Young Lae; Chung, Min Suk

    2013-01-01

    In the Visible Korean project, serially sectioned images of the pelvis were made from a female cadaver. Outlines of significant structures in the sectioned images were drawn and stacked to build surface models. To improve the accessibility and informational content of these data, a five-step process was designed and implemented. First, 154 pelvic…

  13. Theoretical foundations of spatially-variant mathematical morphology part ii: gray-level images.

    Science.gov (United States)

    Bouaynaya, Nidhal; Schonfeld, Dan

    2008-05-01

    In this paper, we develop a spatially-variant (SV) mathematical morphology theory for gray-level signals and images in the Euclidean space. The proposed theory preserves the geometrical concept of the structuring function, which provides the foundation of classical morphology and is essential in signal and image processing applications. We define the basic SV gray-level morphological operators (i.e., SV gray-level erosion, dilation, opening, and closing) and investigate their properties. We demonstrate the ubiquity of SV gray-level morphological systems by deriving a kernel representation for a large class of systems, called V-systems, in terms of the basic SV graylevel morphological operators. A V-system is defined to be a gray-level operator, which is invariant under gray-level (vertical) translations. Particular attention is focused on the class of SV flat gray-level operators. The kernel representation for increasing V-systems is a generalization of Maragos' kernel representation for increasing and translation-invariant function-processing systems. A representation of V-systems in terms of their kernel elements is established for increasing and upper-semi-continuous V-systems. This representation unifies a large class of spatially-variant linear and non-linear systems under the same mathematical framework. Finally, simulation results show the potential power of the general theory of gray-level spatially-variant mathematical morphology in several image analysis and computer vision applications.

  14. Two-dimensional Length Extraction of Ballistic Target from ISAR Images Using a New Scaling Method by Affine Registration

    Directory of Open Access Journals (Sweden)

    Jin Guanghu

    2014-09-01

    Full Text Available The length of ballistic target is one of the most important features for target recognition. It can be extracted from ISAR Images. Unlike from the optical image, the length extraction from ISAR image has two difficulties. The first one is that it is hard to get the actual position of scattering centres by the traditional target extraction method. The second one is that the ISAR image’s cross scale is not known because of the target’s complex rotation. Here we propose two methods to solve these problems. Firstly, we use clustering method to get scattering centers. Secondly we propose to get cross scale of the ISAR images by affine registration. Experiments verified that our approach is realisable and has good performance.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.458-463, DOI:http://dx.doi.org/10.14429/dsj.64.5001

  15. Use of a highly sensitive two-dimensional luminescence imaging system to monitor endogenous bioluminescence in plant leaves

    Directory of Open Access Journals (Sweden)

    Flor-Henry Michel

    2004-11-01

    Full Text Available Abstract Background All living organisms emit spontaneous low-level bioluminescence, which can be increased in response to stress. Methods for imaging this ultra-weak luminescence have previously been limited by the sensitivity of the detection systems used. Results We developed a novel configuration of a cooled charge-coupled device (CCD for 2-dimensional imaging of light emission from biological material. In this study, we imaged photon emission from plant leaves. The equipment allowed short integration times for image acquisition, providing high resolution spatial and temporal information on bioluminescence. We were able to carry out time course imaging of both delayed chlorophyll fluorescence from whole leaves, and of low level wound-induced luminescence that we showed to be localised to sites of tissue damage. We found that wound-induced luminescence was chlorophyll-dependent and was enhanced at higher temperatures. Conclusions The data gathered on plant bioluminescence illustrate that the equipment described here represents an improvement in 2-dimensional luminescence imaging technology. Using this system, we identify chlorophyll as the origin of wound-induced luminescence from leaves.

  16. Artifact-reduced two-dimensional cine steady state free precession for myocardial blood- oxygen-level-dependent imaging.

    Science.gov (United States)

    Zhou, Xiangzhi; Tsaftaris, Sotirios A; Liu, Ying; Tang, Richard; Klein, Rachel; Zuehlsdorff, Sven; Li, Debiao; Dharmakumar, Rohan

    2010-04-01

    To minimize image artifacts in long TR cardiac phase-resolved steady state free precession (SSFP) based blood-oxygen-level-dependent (BOLD) imaging. Nine healthy dogs (four male, five female, 20-25 kg) were studied in a clinical 1.5 Tesla MRI scanner to investigate the effect of temporal resolution, readout bandwidth, and motion compensation on long repetition time (TR) SSFP images. Breath-held 2D SSFP cine sequences with various temporal resolutions (10-204 ms), bandwidths (239-930 Hz/pixel), with and without first-order motion compensation were prescribed in the basal, mid-ventricular, and apical along the short axis. Preliminary myocardial BOLD studies in dogs with controllable coronary stenosis were performed to assess the benefits of artifact-reduction strategies. Shortening the readout time by means of increasing readout bandwidth had no observable reduction in image artifacts. However, increasing the temporal resolution in the presence of first-order motion compensation led to significant reduction in image artifacts. Preliminary studies demonstrated that BOLD signal changes can be reliably detected throughout the cardiac cycle. Artifact-reduction methods used in this study provide significant improvement in image quality compared with conventional long TR SSFP BOLD MRI. It is envisioned that the methods proposed here may enable reliable detection of myocardial oxygenation changes throughout the cardiac cycle with long TR SSFP-based myocardial BOLD MRI. (c) 2010 Wiley-Liss, Inc.

  17. Adulteration screening of botanical materials by a sensitive and model-free approach using infrared spectroscopic imaging and two-dimensional correlation infrared spectroscopy

    Science.gov (United States)

    Chen, Jian-bo; Zhou, Qun; Sun, Su-qin

    2016-11-01

    Infrared (IR) spectroscopy is often used as a simple, fast, and green method for the adulteration screening of botanical materials for foods and herbs. However, the overlapping of absorption signals of various substances significantly decrease the sensitivity and specificity of IR spectroscopy in the detection of adulterated samples. In this research, a model-free approach is proposed for the sensitive and non-targeted screening of botanical materials adulterated by adding other plant materials. First, the spectra of the entities in the test sample are collected by near-infrared spectroscopic imaging and clustered by unsupervised pattern recognition methods. The sample may be adulterated if there are two or more clusters of the entities. Next, the entities of different clusters are characterized by mid-infrared spectroscopy to interpret the chemical compositions to determine the clustering is caused whether by adulteration or other reasons. Second derivative spectroscopy and two-dimensional correlation spectroscopy are often needed to resolve the overlapped bands mathematically or experimentally to find the characteristic signals to identify the authentic and adulterant entities. The feasibility of this approach was proved by the simulated adulterated sample of saffron. In conclusion, botanical materials adulterated by adding other plant materials can be detected by a simple, fast, sensitive, and green screening approach using IR spectroscopic imaging, two-dimensional correlation spectroscopy, and necessary chemometrics techniques.

  18. Optimal voxel size for measuring global gray and white matter proton metabolite concentrations using chemical shift imaging

    DEFF Research Database (Denmark)

    Hanson, Lars Peter Grüner; Adalsteinsson, E; Pfefferbaum, A

    2000-01-01

    Quantification of gray and white matter levels of spectroscopically visible metabolites can provide important insights into brain development and pathological conditions. Chemical shift imaging offers a gain in efficiency for estimation of global gray and white matter metabolite concentrations...

  19. Post calibration of the two-dimensional electron cyclotron emission imaging instrument with electron temperature characteristics of the magnetohydrodynamic instabilities.

    Science.gov (United States)

    Choi, M J; Park, H K; Yun, G S; Nam, Y B; Choe, G H; Lee, W; Jardin, S

    2016-01-01

    The electron cyclotron emission imaging (ECEI) instrument is widely used to study the local electron temperature (Te) fluctuations by measuring the ECE intensity IECE ∝ Te in tokamak plasmas. The ECEI measurement is often processed in a normalized fluctuation quantity against the time averaged value due to complication in absolute calibration. In this paper, the ECEI channels are relatively calibrated using the flat Te assumption of the sawtooth crash or the tearing mode island and a proper extrapolation. The 2-D relatively calibrated electron temperature (Te,rel) images are reconstructed and the displacement amplitude of the magnetohydrodynamic modes can be measured for the accurate quantitative growth analysis.

  20. Hand Vein Images Enhancement Based on Local Gray-level Information Histogram

    OpenAIRE

    Jun Wang; Guoqing Wang; Ming Li; Wenkai Du; Wenhui Yu

    2015-01-01

    Based on the Histogram equalization theory, this paper presents a novel concept of histogram to realize the contrast enhancement of hand vein images, avoiding the lost of topological vein structure or importing the fake vein information. Firstly, we propose the concept of gray-level information histogram, the fundamental characteristic of which is that the amplitudes of the components can objectively reflect the contribution of the gray levels and information to the representation of image in...

  1. Detection of mullerian duct anomalies: diagnostic utility of two dimensional ultrasonography as compared to magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Krishna Pratap Singh Senger

    2016-12-01

    Full Text Available Background: Mullerian duct anomalies (MDAs are a fascinating group of disorders that have varied clinical presentation from being asymptomatic to primary amenorrhea to inability to reproduce. Correct diagnosis of the condition plays a crucial role in management. Imaging plays a pivotal role in making correct diagnosis. This study aims to find the prevalence of MDAs amongst study population and their relation with infertility and also compares diagnostic utility of pelvic ultrasound with MRI. Methods: A randomized diagnostic test evaluation study was conducted in the Department of Radiodiagnosis and Imaging of a tertiary care teaching hospital over a period of 2 years. The patient first underwent pelvic 2D USG in multiple planes using curvilinear probe of 3MHz to 5 MHz. frequency and then MRI. Results: Most common MDA in total study sample and in primary infertility group is arcuate uterus while in recurrent abortions group it is unicornuate uterus. Out of total study sample of 75 patients 2D USG detected 18 cases of MDA while MRI detected 22 cases of MDA. So, 2D USG failed to detect 04 cases of MDA in total study population bringing overall sensitivity of 2D USG as 81.8%, specificity of 100%, PPV of 100%, NPV of 93.4% and accuracy of 94.6%. Conclusions: 2D USG has a few limitations but in view of relatively simple imaging procedure, ease of availability and cost effectiveness it should be utilized as an initial imaging modality in patients with suspicion of MDAs.

  2. Atomic force microscopy imaging of transition metal layered compounds : A two-dimensional stick–slip system

    NARCIS (Netherlands)

    Kerssemakers, J.; Hosson, J.Th.M. De

    1995-01-01

    Various layered transition metal dichalcogenides were scanned with an optical-lever atomic force microscope (AFM). The microscopic images indicate the occurrence of strong lateral stick–slip effects. In this letter, two models are presented to describe the observations due to stick–slip, i.e., eithe

  3. Single-lens Fourier-transform-based optical color image encryption using dual two-dimensional chaotic maps and the Fresnel transform.

    Science.gov (United States)

    Su, Yonggang; Tang, Chen; Li, Biyuan; Chen, Xia; Xu, Wenjun; Cai, Yuanxue

    2017-01-20

    We propose an optical color image encryption system based on the single-lens Fourier transform, the Fresnel transform, and the chaotic random phase masks (CRPMs). The proposed encryption system contains only one optical lens, which makes it more efficient and concise to implement. The introduction of the Fresnel transform makes the first phase mask of the proposed system also act as the main secret key when the input image is a non-negative amplitude-only map. The two CRPMs generated by dual two-dimensional chaotic maps can provide more security to the proposed system. In the proposed system, the key management is more convenient and the transmission volume is reduced greatly. In addition, the secret keys can be updated conveniently in each encryption process to invalidate the chosen plaintext attack and the known plaintext attack. Numerical simulation results have demonstrated the feasibility and security of the proposed encryption system.

  4. Simple and rapid CD4 testing based on large-field imaging system composed of microcavity array and two-dimensional photosensor.

    Science.gov (United States)

    Saeki, Tatsuya; Sugamura, Yuriko; Hosokawa, Masahito; Yoshino, Tomoko; Lim, Tae-Kyu; Harada, Manabu; Matsunaga, Tadashi; Tanaka, Tsuyoshi

    2015-05-15

    This study presents a novel method for CD4 testing based on one-shot large-field imaging. The large-field imaging system was fabricated by a microcavity array and a two-dimensional (2D) photosensor within the desk-top-sized instrument. The microcavity array was employed to separate leukocytes from whole blood based on differences in the size of leukocytes and other blood cells. The large-field imaging system with lower side irradiation enabled acquisition of cell signatures with high signal-to-noise ratio, because the metallic substrate of the microcavity array obstructed excessive excitation light. In this setting, dual-color imaging of CD4(+) and CD8(+) T cells was achieved within the entire image area (64 mm(2)) in 2s. The practical performance of the large-field imaging system was demonstrated by determining the CD4/CD8 ratio in a few microliter of control whole blood as small as those obtained by a finger prick. The CD4/CD8 ratios measured using the large-field imaging system correlated well with those measured by microscopic analysis. These results indicate that our proposed system provides a simple and rapid CD4 testing for the application of HIV/AIDS treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Post calibration of the two-dimensional electron cyclotron emission imaging instrument with electron temperature characteristics of the magnetohydrodynamic instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Choi, M. J., E-mail: mjchoi@nfri.re.kr [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Park, H. K. [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Yun, G. S.; Nam, Y. B.; Choe, G. H. [Pohang University of Science and Technology, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Lee, W. [Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Jardin, S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2016-01-15

    The electron cyclotron emission imaging (ECEI) instrument is widely used to study the local electron temperature (T{sub e}) fluctuations by measuring the ECE intensity I{sub ECE} ∝ T{sub e} in tokamak plasmas. The ECEI measurement is often processed in a normalized fluctuation quantity against the time averaged value due to complication in absolute calibration. In this paper, the ECEI channels are relatively calibrated using the flat T{sub e} assumption of the sawtooth crash or the tearing mode island and a proper extrapolation. The 2-D relatively calibrated electron temperature (T{sub e,rel}) images are reconstructed and the displacement amplitude of the magnetohydrodynamic modes can be measured for the accurate quantitative growth analysis.

  6. Two-Dimensional Standing Wave Total Internal Reflection Fluorescence Microscopy: Superresolution Imaging of Single Molecular and Biological Specimens

    OpenAIRE

    2007-01-01

    The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium. The

  7. [An improvement on the two-dimensional convolution method of image reconstruction and its application to SPECT].

    Science.gov (United States)

    Suzuki, S; Arai, H

    1990-04-01

    In single-photon emission computed tomography (SPECT) and X-ray CT one-dimensional (1-D) convolution method is used for their image reconstruction from projections. The method makes a 1-D convolution filtering on projection data with a 1-D filter in the space domain, and back projects the filtered data for reconstruction. Images can also be reconstructed by first forming the 2-D backprojection images from projections and then convoluting them with a 2-D space-domain filter. This is the reconstruction by the 2-D convolution method, and it has the opposite reconstruction process to the 1-D convolution method. Since the 2-D convolution method is inferior to the 1-D convolution method in speed in reconstruction, it has no practical use. In the actual reconstruction by the 2-D convolution method, convolution is made on a finite plane which is called convolution window. A convolution window of size N X N needs a 2-D discrete filter of the same size. If better reconstructions are achieved with small convolution windows, the reconstruction time for the 2-D convolution method can be reduced. For this purpose, 2-D filters of a simple function form are proposed which can give good reconstructions with small convolution windows. They are here defined on a finite plane, depending on the window size used, although a filter function is usually defined on the infinite plane. They are however set so that they better approximate the property of a 2-D filter function defined on the infinite plane. Filters of size N X N are thus determined. Their value varies with window size. The filters are applied to image reconstructions of SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Two-dimensional calculus

    CERN Document Server

    Osserman, Robert

    2011-01-01

    The basic component of several-variable calculus, two-dimensional calculus is vital to mastery of the broader field. This extensive treatment of the subject offers the advantage of a thorough integration of linear algebra and materials, which aids readers in the development of geometric intuition. An introductory chapter presents background information on vectors in the plane, plane curves, and functions of two variables. Subsequent chapters address differentiation, transformations, and integration. Each chapter concludes with problem sets, and answers to selected exercises appear at the end o

  9. Two dimensional vernier

    Science.gov (United States)

    Juday, Richard D. (Inventor)

    1992-01-01

    A two-dimensional vernier scale is disclosed utilizing a cartesian grid on one plate member with a polar grid on an overlying transparent plate member. The polar grid has multiple concentric circles at a fractional spacing of the spacing of the cartesian grid lines. By locating the center of the polar grid on a location on the cartesian grid, interpolation can be made of both the X and Y fractional relationship to the cartesian grid by noting which circles coincide with a cartesian grid line for the X and Y direction.

  10. Composite x-ray image assembly for large-field digital mammography with one- and two-dimensional positioning of a focal plane array

    Science.gov (United States)

    Halama, G.; McAdoo, J.; Liu, H.

    1998-01-01

    To demonstrate the feasibility of a novel large-field digital mammography technique, a 1024 x 1024 pixel Loral charge-coupled device (CCD) focal plane array (FPA) was positioned in a mammographic field with one- and two-dimensional scan sequences to obtain 950 x 1800 pixel and 3600 x 3600 pixel composite images, respectively. These experiments verify that precise positioning of FPAs produced seamless composites and that the CCD mosaic concept has potential for high-resolution, large-field imaging. The proposed CCD mosaic concept resembles a checkerboard pattern with spacing left between the CCDs for the driver and readout electronics. To obtain a complete x-ray image, the mosaic must be repositioned four times, with an x-ray exposure at each position. To reduce the patient dose, a lead shield with appropriately patterned holes is placed between the x-ray source and the patient. The high-precision motorized translation stages and the fiber-coupled-scintillating-screen-CCD sensor assembly were placed in the position usually occupied by the film cassette. Because of the high mechanical precision, seamless composites were constructed from the subimages. This paper discusses the positioning, image alignment procedure, and composite image results. The paper only addresses the formation of a seamless composite image from subimages and will not consider the effects of the lead shield, multiple CCDs, or the speed of motion.

  11. Assessment of Age-related Changes in Left Ventricular Twist by Two-dimensional Ultrasound Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; XIANG Feixiang; XIE Mingxing; FU Manli; WANG Xinfang; L(U) Qing; HAN Wei; ZHANG Jing; LIU Yingying; WANG Jing

    2007-01-01

    To assess the normal value of left ventricular twist (LVtw) and examine the changeswith normal aging by 2-dimensional ultrasound speckle-tracking imaging (STI), 121 healthy volunteers were divided into three age groups: a youth group (19-45 y old), a middle-age group (46-64 y old ) and an old-age group (≥65 y old). Basal and apical short-axis images of left ventricular were ac- quired to analyse LV rotation (LVrot) and LVrot velocity. LVtw and LVtw velocity was defined as apical LVrot and LVrot velocity relative to the base. Peak twist (Ptw), twist at aortic valve closure (AVCtw), twist at mitral valve opening (MVOtw), untwisting rate (UntwR), half time of untwisting (HTU), peak twist velocity (PTV), time to peak twist velocity (TPTV), peak untwisting velocity (PUV), time to peak untwisting velocity (TPUV) were separately measured. The results showed that the normal LV performs a wringing motion with a clockwise rotation at the base and a counterclock- wise rotation at the apex (as seen from the apex). The LVtw velocity showed a systolic counterclock- wise twist followed by a diastolic clockwise twist. Peak twist develops near the end of systole (96%±4.2% of systole). With aging, Ptw, AVCtw, MVOtw, HTU and PUV increased significantly (P<0.05) and UntwR decreased significantly (P<0.05). However, no significant differences in TPUV, PTV and TPTV were noted among the 3 groups (P0.05). It is concluded that LV twist can be meas- ured non-invasively by 2-dimensional ultrasound STI imaging. The age-related changes of LVtw should be fully taken into consideration in the assessment of LV function.

  12. Two-dimensional standing wave total internal reflection fluorescence microscopy: superresolution imaging of single molecular and biological specimens.

    Science.gov (United States)

    Chung, Euiheon; Kim, Daekeun; Cui, Yan; Kim, Yang-Hyo; So, Peter T C

    2007-09-01

    The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium. The excitation region resulting in low background fluorescence. We present even higher resolution wide-field biological imaging by use of standing wave total internal reflection fluorescence (SW-TIRF). Evanescent standing wave (SW) illumination is used to generate a sinusoidal high spatial frequency fringe pattern on specimen for lateral resolution enhancement. To prevent thermal drift of the SW, novel detection and estimation of the SW phase with real-time feedback control is devised for the stabilization and control of the fringe phase. SW-TIRF is a wide-field superresolution technique with resolution better than a fifth of emission wavelength or approximately 100 nm lateral resolution. We demonstrate the performance of the SW-TIRF microscopy using one- and two-directional SW illumination with a biological sample of cellular actin cytoskeleton of mouse fibroblast cells as well as single semiconductor nanocrystal molecules. The results confirm the superior resolution of SW-TIRF in addition to the merit of a high signal/background ratio from TIRF microscopy.

  13. Image analysis method for the measurement of water saturation in a two-dimensional experimental flow tank

    Science.gov (United States)

    Belfort, Benjamin; Weill, Sylvain; Lehmann, François

    2017-07-01

    A novel, non-invasive imaging technique is proposed that determines 2D maps of water content in unsaturated porous media. This method directly relates digitally measured intensities to the water content of the porous medium. This method requires the classical image analysis steps, i.e., normalization, filtering, background subtraction, scaling and calibration. The main advantages of this approach are that no calibration experiment is needed, because calibration curve relating water content and reflected light intensities is established during the main monitoring phase of each experiment and that no tracer or dye is injected into the flow tank. The procedure enables effective processing of a large number of photographs and thus produces 2D water content maps at high temporal resolution. A drainage/imbibition experiment in a 2D flow tank with inner dimensions of 40 cm × 14 cm × 6 cm (L × W × D) is carried out to validate the methodology. The accuracy of the proposed approach is assessed using a statistical framework to perform an error analysis and numerical simulations with a state-of-the-art computational code that solves the Richards' equation. Comparison of the cumulative mass leaving and entering the flow tank and water content maps produced by the photographic measurement technique and the numerical simulations demonstrate the efficiency and high accuracy of the proposed method for investigating vadose zone flow processes. Finally, the photometric procedure has been developed expressly for its extension to heterogeneous media. Other processes may be investigated through different laboratory experiments which will serve as benchmark for numerical codes validation.

  14. Probabilistic Visual Secret Sharing Schemes for Gray-scale images and Color images

    CERN Document Server

    Wang, Dao-Shun; Li, Xiaobo

    2007-01-01

    Visual secrete sharing (VSS) is an encryption technique that utilizes human visual system in the recovering of the secret image and it does not require any complex calculation. Pixel expansion has been a major issue of VSS schemes. A number of probabilistic VSS schemes with minimum pixel expansion have been proposed for binary secret images. This paper presents a general probabilistic (k, n)-VSS scheme for gray-scale images and another scheme for color images. With our schemes, the pixel expansion can be set to a user-defined value. When this value is 1, there is no pixel expansion at all. The quality of reconstructed secret images, measured by Average Relative Difference, is equivalent to Relative Difference of existing deterministic schemes. Previous probabilistic VSS schemes for black-and-white images with respect to pixel expansion can be viewed as special cases of the schemes proposed here

  15. Development and testing of a two-dimensional ultrasonic laboratory model system for seismic imaging of heterogeneous structures

    Science.gov (United States)

    Mo, Yike; Karaman, Hakki; Greenhalgh, Stewart

    2014-05-01

    To tackle the challenges and imaging problems of complex structures, we have recently assembled within the Wave Propagation Lab at ETH Zürich a simple 2D ultrasonic model facility in which the simulated geological structures are constructed from thin (2 mm thickness) metal and plastic sheets, cut and bonded together. The models were used, in full recognition of the similitude relations, to investigate reflections from beneath a low velocity distorting overburden. Besides uniform and irregular near surface layers, flat and dipping interfaces as well as rectangular high and low velocity block inserts were investigated. The experiments entailed the use of a piezoelectric source driven by a pulse amplifier at ultrasonic frequencies (20-300 kHz) to generate Lamb waves in the plate, which are detected by piezoelectric receivers and recorded digitally on a National Instruments recording system, under SignalExpress software control. In the lab system, a single cycle sinusoidal pulse with a negative onset (5 μs pulse width and 600 V pulse voltage) was selected as the optimized source pulse. Transducers can be placed along the thin edges of the plate in reflection mode (same edge) or transmission mode (opposite edges, or perpendicular edges). Alternatively they can be mounted on the flat planar surface of the plate to simulate a crosshole survey. Data were originally collected in all different recording geometries over a homogenous aluminium model for calibration purposes and to examine wave modes and propagation characteristics. The two dominant Lamb waves recorded are the fundamental symmetric mode (non-dispersive) and the fundamental antisymmetric (flexural) dispersive mode, which is normally absent when the source transducer is located on a model edge but dominant when it is on the flat planar surface of the plate. Only the symmetric Lamb mode can be used as a proxy for 2D propagation in an extended medium (the field situation). Experimental group and phase velocity

  16. Tip-Enhanced Raman Scattering Imaging of Two-Dimensional Tungsten Disulfide with Optimized Tip Fabrication Process

    Science.gov (United States)

    Lee, Chanwoo; Kim, Sung Tae; Jeong, Byeong Geun; Yun, Seok Joon; Song, Young Jae; Lee, Young Hee; Park, Doo Jae; Jeong, Mun Seok

    2017-01-01

    We successfully achieve the tip-enhanced nano Raman scattering images of a tungsten disulfide monolayer with optimizing a fabrication method of gold nanotip by controlling the concentration of etchant in an electrochemical etching process. By applying a square-wave voltage supplied from an arbitrary waveform generator to a gold wire, which is immersed in a hydrochloric acid solution diluted with ethanol at various ratios, we find that both the conical angle and radius of curvature of the tip apex can be varied by changing the ratio of hydrochloric acid and ethanol. We also suggest a model to explain the origin of these variations in the tip shape. From the systematic study, we find an optimal condition for achieving the yield of ~60% with the radius of ~34 nm and the cone angle of ~35°. Using representative tips fabricated under the optimal etching condition, we demonstrate the tip-enhanced Raman scattering experiment of tungsten disulfide monolayer grown by a chemical vapor deposition method with a spatial resolution of ~40 nm and a Raman enhancement factor of ~4,760.

  17. Gray-scale and color optical encryption based on computational ghost imaging

    Science.gov (United States)

    Tanha, Mehrdad; Kheradmand, Reza; Ahmadi-Kandjani, Sohrab

    2012-09-01

    We propose two approaches for optical encryption based on computational ghost imaging. These methods have the capability of encoding ghost images reconstructed from gray-scale images and colored objects. We experimentally demonstrate our approaches under eavesdropping in two different setups, thereby proving the robustness and simplicity thereof for encryption compared with previous algorithms.

  18. Fast retrieval of calcification from sequential intravascular ultrasound gray-scale images.

    Science.gov (United States)

    Zheng, Sun; Bing-Ru, Liu

    2016-08-12

    Intravascular ultrasound (IVUS)-based tissue characterization is invaluable for the computer-aided diagnosis and interventional treatment of cardiac vessel diseases. Although the analysis of raw backscattered signals allows more accurate plaque characterization than gray-scale images, its applications are limited due to its nature of electrocardiogram-gated acquisition. Images acquired by IVUS devices that do not allow the acquisition of raw signals cannot be characterized. To address these limitations, we developed a method for fast frame-by-frame retrieval and location of calcification according to the jump features of radial gray-level variation curves from sequential IVUS gray-scale images. The proposed method consists of three main steps: (1) radial gray-level variation curves are extracted from each filtered polar view, (2) sequential images are preliminarily queried according to the maximal slopes of radial gray-level variation curves, and finally, (3) key frames that include calcification are selected through checking the gray-level features of successive pixel columns in the preliminary results. Experimental results with clinically acquired in vivo data sets indicate key frames that include calcification can be retrieved with the advantages of simplicity, high efficiency, and accuracy. Recognition results correlate well with manual characterization results obtained by experienced physicians and through virtual histology.

  19. Two-dimensional cubic convolution.

    Science.gov (United States)

    Reichenbach, Stephen E; Geng, Frank

    2003-01-01

    The paper develops two-dimensional (2D), nonseparable, piecewise cubic convolution (PCC) for image interpolation. Traditionally, PCC has been implemented based on a one-dimensional (1D) derivation with a separable generalization to two dimensions. However, typical scenes and imaging systems are not separable, so the traditional approach is suboptimal. We develop a closed-form derivation for a two-parameter, 2D PCC kernel with support [-2,2] x [-2,2] that is constrained for continuity, smoothness, symmetry, and flat-field response. Our analyses, using several image models, including Markov random fields, demonstrate that the 2D PCC yields small improvements in interpolation fidelity over the traditional, separable approach. The constraints on the derivation can be relaxed to provide greater flexibility and performance.

  20. Magnetic Imaging of Applied and Propagating Action Currents in Cardiac Tissue Slices: Determination of Anisotropic Electrical Conductivities in a Two-Dimensional Bidomain.

    Science.gov (United States)

    Staton, Daniel Joseph

    We describe the first, high-resolution magnetic images of applied currents and propagating action currents in slices of canine cardiac tissue. This tissue was maintained in vitro at 37^circC. Our main conclusions are summarized as follows: the action currents produce magnetic fields which are measurable; during the initial stages of the propagating action potential, small, expanding, quatrefoil loops of current develop; the magnetic fields produced by repolarization currents are larger than previously anticipated. Most of the current associated with the propagating action potential is confined within the wavefront and should be magnetically silent; however, differences in the intracellular and extracellular electrical conductivities, in both the longitudinal and transverse fiber directions, are great enough that expanding quatrefoil current densities are associated with the wavefront and produce measurable magnetic fields. Since action currents are affected by the electrical conductivities, it is of interest to determine their values, which depend not only upon the tissue characteristics, but also on the mathematical model used to interpret the measured data. In our analysis of current injection, we use the anisotropic bidomain model which incorporates a passive, linear membrane. We introduce theoretical techniques to calculate the anisotropic conductivities of a two-dimensional bidomain. To apply these techniques to magnetic fields resulting from current injection into cardiac tissue slices, we need to improve the higher spatial frequency content of our present measurements. This may be done by measuring the magnetic field closer to the cardiac slice (presently 2.5 mm), decreasing the sampling interval of the measurement, and increasing the sampling area of the field. Magnetic fields are produced by propagating action currents, which are in turn the result of the propagating action potential. From the magnetic field, we directly image isochronal transmembrane

  1. [Imaging Observation of Scalp Acupuncture on Brain Gray Matter Injury in Stroke Patients with Cerebral Infarction].

    Science.gov (United States)

    Lang, Yi; Cui, Fang-yuan; Li, Kuang-shi; Tan, Zhong-jian; Zou, Yi-huai

    2016-03-01

    To study features of brain gray matter injury in cerebral infarction patients and intervention of scalp acupuncture by using voxel-based morphology. A total of 16 cerebral infarction patients were recruited in this study, and assigned to the scalp acupuncture group and the control group, 8 in each group. Another 16 healthy volunteers were recruited as a normal group. All patients received scanning of T1 structure. Images were managed using VBM8 Software package. Difference of the gray matter structure was compared among the scalp acupuncture group, the control group, and the healthy volunteers. Compared with healthy volunteers, gray matter injury of cerebral infarction patients mainly occurred in 14 brain regions such as cingulate gyrus, precuneus, cuneus, anterior central gyrus, insular lobe, and so on. They were mainly distributed in affected side. Two weeks after treatment when compared with healthy volunteers, gray matter injury of cerebral infarction patients in the scalp acupuncture group still existed in 8 brain regions such as bilateral lingual gyrus, posterior cingulate gyrus, left cuneus, right precuneus, and so on. New gray matter injury occurred in lingual gyrus and posterior cingulate gyrus. Two weeks after treatment when compared with healthy volunteers, gray matter injury of cerebral infarction patients in the control group existed in 23 brain regions: bilateral anterior cingulum, caudate nucleus, cuneate lobe, insular lobe, inferior frontal gyrus, medial frontal gyrus, precuneus, paracentral lobule, superior temporal gyrus, middle temporal gyrus, lingual gyrus, right postcentral gyrus, posterior cingulate gyrus, precentral gyrus, middle frontal gyrus, and so on. New gray matter injury still existed in 9 cerebral regions such as lingual gyrus, posterior cingulate gyrus, postcentral gyrus, and so on. Brain gray matter structure is widely injured after cerebral infarction. Brain gray matter volume gradually decreased as time went by. Combined use of

  2. Comparing differential tissue harmonic imaging with tissue harmonic and fundamental gray scale imaging of the liver.

    Science.gov (United States)

    Chiou, See-Ying; Forsberg, Flemming; Fox, Traci B; Needleman, Laurence

    2007-11-01

    The purpose of this study was to compare fundamental gray scale sonography, tissue harmonic imaging (THI), and differential tissue harmonic imaging (DTHI) for depicting normal and abnormal livers. The in vitro lateral resolution of DTHI, THI, and sonography was assessed in a phantom. Sagittal and transverse images of right and left hepatic lobes of 5 volunteers and 20 patients and images of 27 liver lesions were also acquired. Three independent blinded readers scored all randomized images for noise, detail resolution, image quality, and margin (for lesions) on a 7-point scale. Next, images from the same location obtained with all 3 modes were compared blindly side by side and rated by all readers. Contrast-to-noise ratios were calculated for the lesions, and the depth of penetration (centimeters) was determined for all images. In vitro, the lateral resolution of DTHI was significantly better than fundamental sonography (P = .009) and showed a trend toward significance versus THI (P = .06). In the far field, DTHI performed better than both modes (P images were scored, and for all parameters, DTHI and THI did better than sonography (P tissue harmonic imaging scored significantly higher than THI with regard to detail resolution and image quality (P Tissue harmonic imaging and DTHI do better than fundamental sonography for hepatic imaging, with DTHI being rated the best of the 3 techniques.

  3. Color image encryption by using Yang-Gu mixture amplitude-phase retrieval algorithm in gyrator transform domain and two-dimensional Sine logistic modulation map

    Science.gov (United States)

    Sui, Liansheng; Liu, Benqing; Wang, Qiang; Li, Ye; Liang, Junli

    2015-12-01

    A color image encryption scheme is proposed based on Yang-Gu mixture amplitude-phase retrieval algorithm and two-coupled logistic map in gyrator transform domain. First, the color plaintext image is decomposed into red, green and blue components, which are scrambled individually by three random sequences generated by using the two-dimensional Sine logistic modulation map. Second, each scrambled component is encrypted into a real-valued function with stationary white noise distribution in the iterative amplitude-phase retrieval process in the gyrator transform domain, and then three obtained functions are considered as red, green and blue channels to form the color ciphertext image. Obviously, the ciphertext image is real-valued function and more convenient for storing and transmitting. In the encryption and decryption processes, the chaotic random phase mask generated based on logistic map is employed as the phase key, which means that only the initial values are used as private key and the cryptosystem has high convenience on key management. Meanwhile, the security of the cryptosystem is enhanced greatly because of high sensitivity of the private keys. Simulation results are presented to prove the security and robustness of the proposed scheme.

  4. Two-dimensional fast imaging employing steady-state acquisition (FIESTA) cine acquisition of fetal non-central nervous system abnormalities.

    Science.gov (United States)

    Shen, Shu-Huei; Guo, Wan-Yuo; Hung, Jeng-Hsiu

    2007-09-01

    To evaluate the value of two-dimensional fast imaging employing steady-state acquisition (2D FIESTA) cine MR with parallel imaging techniques in the diagnosis of fetal non-central nervous system (CNS) anomalies. A total of 28 pregnant women were referred for further MR evaluation on fetuses after abnormal sonographic results. A total of 33 fetal MR examinations were performed by a 1.5 T MR scanner with eight-channel phase-arrayed body coils. Single-shot fast spin-echo (SSFSE(R), GE) of three orthogonal planes and 2D FIESTA for cine fetal MR of three sagittal planes (midsagittal and 10 mm off midline on left and right) were routinely acquired. Additional planes on target organs with variable imaging frames were added if indicated. Nine of the 33 examinations (9/33; 27.3%) had motion artifacts obscuring the detail in SSFSE imaging; 2D FIESTA imaging provided motion-artifact-free imaging in all of them. Cine 2D FIESTA imaging provided additional information on the visceral peristalsis. The information helped in differentiating dilated gastrointestinal (GI) tract from other intraabdominal cystic lesions and in confirming the nature and level of GI tract obstruction. With sub-half-second temporal resolution of the 2D FIESTA sequences, fetal movement is no longer problematic. In addition to the anatomical information also provided by conventional SSFSE sequences, 2D FIESTA demonstrates information on motility and peristalsis of hollow organs and helps the diagnosis of fetal visceral anomalies. (c) 2007 Wiley-Liss, Inc.

  5. Two-dimensional optical spectroscopy

    CERN Document Server

    Cho, Minhaeng

    2009-01-01

    Discusses the principles and applications of two-dimensional vibrational and optical spectroscopy techniques. This book provides an account of basic theory required for an understanding of two-dimensional vibrational and electronic spectroscopy.

  6. 基于FPGA快速二维DCT图像编码结构%FPGA Rapid Two-dimensional DCT Image Coding Structure

    Institute of Scientific and Technical Information of China (English)

    龙飞; 李良荣; 李绪诚

    2012-01-01

    本文提出了一种二维DCT快速算法的FPGA实现结构,采用行列分解算法将二维DCT分解成两个一维DCT和一个转置缓冲器组成的结构,其中一雏DCT借鉴Arai DCT算法,并采取了FPGA特有的并行的流水线技术,该结构极大减少了加法器和乘法器的数量,节省了计算时间.该结构的特点是高数据吞吐率、硬件资源消耗少,功耗低.实验结果证明了二维DCT核设计的正确性,适合图像的实时处理.%In this paper, a two-dimensional DCT fast algorithm for FPGA implementation structure. Decomposition algorithm using the line-column, 2D-DCT is broken down into the structure of two 1D-DCT and a transpose buffer, and 1D-DCT is learn from Arai DCT algorithm, and mining is indeed a unique parallel pipeline technique in FPGA. The structure greatly reduces the adder and multiplier is the number, to save calculation time. The structure is characterized by high data throughput, the hardware resource consumption, low power consumption. The experimental results show the correctness of the two-dimensional DCT core design, suitable for real-time processing of the image.

  7. ProteomeGRID: towards a high-throughput proteomics pipeline through opportunistic cluster image computing for two-dimensional gel electrophoresis.

    Science.gov (United States)

    Dowsey, Andrew W; Dunn, Michael J; Yang, Guang-Zhong

    2004-12-01

    The quest for high-throughput proteomics has revealed a number of critical issues. Whilst improved two-dimensional gel electrophoresis (2-DE) sample preparation, staining and imaging issues are being actively pursued by industry, reliable high-throughput spot matching and quantification remains a significant bottleneck in the bioinformatics pipeline, thus restricting the flow of data to mass spectrometry through robotic spot excision and protein digestion. To this end, it is important to establish a full multi-site Grid infrastructure for the processing, archival, standardisation and retrieval of proteomic data and metadata. Particular emphasis needs to be placed on large-scale image mining and statistical cross-validation for reliable, fully automated differential expression analysis, and the development of a statistical 2-DE object model and ontology that underpins the emerging HUPO PSI GPS (Human Proteome Organization Proteomics Standards Initiative General Proteomics Standards). The first step towards this goal is to overcome the computational and communications burden entailed by the image analysis of 2-DE gels with Grid enabled cluster computing. This paper presents the proTurbo framework as part of the ProteomeGRID, which utilises Condor cluster management combined with CORBA communications and JPEG-LS lossless image compression for task farming. A novel probabilistic eager scheduler has been developed to minimise make-span, where tasks are duplicated in response to the likelihood of the Condor machines' owners evicting them. A 60 gel experiment was pair-wise image registered (3540 tasks) on a 40 machine Linux cluster. Real-world performance and network overhead was gauged, and Poisson distributed worker evictions were simulated. Our results show a 4:1 lossless and 9:1 near lossless image compression ratio and so network overhead did not affect other users. With 40 workers a 32x speed-up was seen (80% resource efficiency), and the eager scheduler reduced the

  8. Application of a single-instruction computer to dilation and erosion of gray-valued images

    Science.gov (United States)

    Laplante, Phillip A.

    1992-11-01

    In this paper, the single instruction architecture is used to construct circuitry to perform dilation and erosion of gray valued images, where the gray values are discrete but limited only by the number of bits chosen for the binary encoding. In addition, methods for minimizing the number of cells needed, using basic digital techniques, are discussed. While others have constructed architectures for gray valued dilation and erosion, these are based on non- homogeneous circuits, and typically use Umbra transformations to handle the gray values, rather than binary encoding. Finally, it is shown that the half-adder elements used in the single instruction architecture can easily be replaced with uniform multiplexer cells in deference to the McCulloch-Pitts model of the neuron. This analogy between the single instruction architecture and the neuronal construction of the brain is intentional.

  9. Two-dimensional micro-beam imaging of trace elements in a single plankton measured by a synchrotron radiation X-ray fluorescence analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ezoe, Masako; Sasaki, Miho; Hokura, Akiko; Nakai, Izumi [Tokyo Univ. of Science, Faculty of Science, Tokyo (Japan); Terada, Yasuko [Japan Synchrotron Radiation Research Inst., Mikazuki, Hyogo (Japan); Yoshinaga, Tatsuki; Tukamoto, Katsumi [Tokyo Univ., Ocean Research Inst., Tokyo (Japan); Hagiwara, Atsushi [Nagasaki Univ., Graduate School of Science and Technology, Bunkyou, Nagasaki (Japan)

    2002-10-01

    Two-dimensional imaging and a quantitative analysis of trace elements in rotifer, Brachionus plicatilis, belonging to zooplankton, were carried out by a synchrotron radiation X-ray fluorescence analysis (SR-XRF). The XRF imaging revealed that female rotifers accumulated Fe and Zn in the digestive organ and Fe, Zn, Cu, and Ca in the sexual organs, while the Mn level was high in the head. From a quantitative analysis by inductively coupled plasma mass spectrometry (ICP-MS), we found that rotifers eat the chlorella and accumulate the above elements in the body. The result of quantitative analyses of Mn, Cu, and Zn by SR-XRF in a single sample is in fair agreement with the average values determined by ICP-MS analyses, which were obtained by measuring a large number of rotifers, digested by nitric acid. The present study has demonstrated that SR-XRF is an effective tool for the trace element analysis of a single individual of rotifer. (author)

  10. Segment-orientated analysis of two-dimensional strain and strain rate as assessed by velocity vector imaging in patients with acute myocardial infarction

    Directory of Open Access Journals (Sweden)

    Thomas Butz, Corinna N. Lang, Marc van Bracht, Magnus W. Prull, Hakan Yeni, Petra Maagh, Gunnar Plehn, Axel Meissner, Hans-Joachim Trappe

    2011-01-01

    Full Text Available Aims: Strain rate imaging techniques have been proposed for the detection of ischemic or viable myocardium in coronary artery disease, which is still a challenge in clinical cardiology. This retrospective comparative study analyzed regional left ventricular function and scaring with two-dimensional strain (2DS in the first 4 to 10 days after acute anterior myocardial infarction (AMI.Methods and results: The study population consisted of 32 AMI patients with an LAD occlusion and successful reperfusion. The assessment of peak systolic 2DS and peak systolic strain rate (SR was performed segment-oriented with the angle-independent speckle tracking algorithm Velocity Vector Imaging (VVI. The infarcted, adjacent and non-infarcted segments were revealed by late enhancement MRI (LE-MRI, which was used as reference for the comparison with 2DS. The infarcted segments showed a significant decrease of tissue velocities, 2DS and SR in comparison to the non-affected segments.Conclusion: 2DS and SR as assessed by VVI seem to be a suitable approach for echocardiographic quantification of global and regional myocardial function as well as a promising tool for multimodal risk stratification after anterior AMI.

  11. Multi-spectral image enhancement algorithm based on keeping original gray level

    Science.gov (United States)

    Wang, Tian; Xu, Linli; Yang, Weiping

    2016-11-01

    Characteristics of multi-spectral imaging system and the image enhancement algorithm are introduced.Because histogram equalization and some other image enhancement will change the original gray level,a new image enhancement algorithm is proposed to maintain the gray level.For this paper, we have chosen 6 narrow-bands multi-spectral images to compare,the experimental results show that the proposed method is better than those histogram equalization and other algorithm to multi-spectral images.It also insures that histogram information contained in original features is preserved and guarantees to make use of data class information.What's more,on the combination of subjective and objective sharpness evaluation,details of the images are enhanced and noise is weaken.

  12. Interpolation by two-dimensional cubic convolution

    Science.gov (United States)

    Shi, Jiazheng; Reichenbach, Stephen E.

    2003-08-01

    This paper presents results of image interpolation with an improved method for two-dimensional cubic convolution. Convolution with a piecewise cubic is one of the most popular methods for image reconstruction, but the traditional approach uses a separable two-dimensional convolution kernel that is based on a one-dimensional derivation. The traditional, separable method is sub-optimal for the usual case of non-separable images. The improved method in this paper implements the most general non-separable, two-dimensional, piecewise-cubic interpolator with constraints for symmetry, continuity, and smoothness. The improved method of two-dimensional cubic convolution has three parameters that can be tuned to yield maximal fidelity for specific scene ensembles characterized by autocorrelation or power-spectrum. This paper illustrates examples for several scene models (a circular disk of parametric size, a square pulse with parametric rotation, and a Markov random field with parametric spatial detail) and actual images -- presenting the optimal parameters and the resulting fidelity for each model. In these examples, improved two-dimensional cubic convolution is superior to several other popular small-kernel interpolation methods.

  13. Near-infrared (NIR) imaging analysis of polylactic acid (PLA) nanocomposite by multiple-perturbation two-dimensional (2D) correlation spectroscopy

    Science.gov (United States)

    Shinzawa, Hideyuki; Murakami, Takurou N.; Nishida, Masakazu; Kanematsu, Wataru; Noda, Isao

    2014-07-01

    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.

  14. Characterization of a two-dimensional temperature field within a rapid compression machine using a toluene planar laser-induced fluorescence imaging technique

    Science.gov (United States)

    Strozzi, Camille; Sotton, Julien; Mura, Arnaud; Bellenoue, Marc

    2009-12-01

    The homogeneous charge compression ignition (HCCI) combustion process is an advanced operating mode for automotive engines. The self-ignition mechanisms that occur within the combustion chamber exhibit extreme temperature dependence. Therefore, the thorough understanding of corresponding phenomena requires the use of diagnostic methods featuring a sufficient thermal sensitivity, applicable in severe conditions similar to those encountered within engines. In this respect, toluene planar laser-induced fluorescence (PLIF) is applied to the inert compression flow generated within an optical rapid compression machine (RCM). A relatively simple diagnostic system is retained: a single wavelength excitation device (266 nm) and a single (filtered) collection system. This diagnostic system is associated with an image processing strategy specifically adapted to RCM devices. Despite the severe conditions under consideration (40 bar, 700-950 K), the method allows us to obtain relatively large two-dimensional temperature fields that display a level of description seldom achieved in such devices. In particular the temperature gradients, which play a crucial role in HCCI combustion processes, can be estimated. The present experimental results confirm the good reliability and accuracy of the method. The information gathered with this toluene PLIF method puts in evidence its high potentialities for the study of aero-thermal-reactive processes as they take place in real engine conditions. The retained strategy also brings new possibilities of non-intrusive analysis for flows practically encountered within industrial devices.

  15. Derivatization technique to increase the spectral selectivity of two-dimensional Fourier transform infrared focal plane array imaging: analysis of binder composition in aged oil and tempera paint.

    Science.gov (United States)

    Zumbühl, Stefan; Scherrer, Nadim C; Eggenberger, Urs

    2014-01-01

    The interpretation of standard Fourier transform infrared spectra (FT-IR) on oil-based paint samples often suffers from interfering bands of the different compounds, namely, binder, oxidative aging products, carboxylates formed during aging, and several pigments and fillers. The distinction of the aging products such as ketone and carboxylic acid functional groups pose the next problem, as these interfere with the triglyceride esters of the oil. A sample preparation and derivatization technique using gaseous sulfur tetrafluoride (SF4), was thus developed with the aim to discriminate overlapping signals and achieve a signal enhancement on superposed compounds. Of particular interest in this context is the signal elimination of the broad carboxylate bands of the typical reaction products developing during the aging processes in oil-based paints, as well as signal interference originating from several typical pigments in this spectral range. Furthermore, it is possible to distinguish the different carbonyl-containing functional groups upon selective alteration. The derivatization treatment can be applied to both microsamples and polished cross sections. It increases the selectivity of the infrared spectroscopy technique in a fundamental manner and permits the identification and two-dimensional (2D) localization of binder components in aged paint samples at the micrometer scale. The combination of SF4 derivatization with high-resolution 2D FT-IR focal plane array (FPA) imaging delivers considerable advances to the study of micro-morphological processes involving organic compounds.

  16. Structural Angle and Power Images Reveal Interrelated Gray and White Matter Abnormalities in Schizophrenia

    Directory of Open Access Journals (Sweden)

    Lai Xu

    2012-01-01

    Full Text Available We present a feature extraction method to emphasize the interrelationship between gray and white matter and identify tissue distribution abnormalities in schizophrenia. This approach utilizes novel features called structural phase and magnitude images. The phase image indicates the relative contribution of gray and white matter, and the magnitude image reflects the overall tissue concentration. Three different analyses are applied to the phase and magnitude images obtained from 120 healthy controls and 120 schizophrenia patients. First, a single-subject subtraction analysis is computed for an initial evaluation. Second, we analyze the extracted features using voxel based morphometry (VBM to detect voxelwise group differences. Third, source based morphometry (SBM analysis was used to determine abnormalities in structural networks that co-vary in a similar way. Six networks were identified showing significantly lower white-to-gray matter in schizophrenia, including thalamus, right precentral-postcentral, left pre/post-central, parietal, right cuneus-frontal, and left cuneus-frontal sources. Interestingly, some networks look similar to functional patterns, such as sensory-motor and vision. Our findings demonstrate that structural phase and magnitude images can naturally and efficiently summarize the associated relationship between gray and white matter. Our approach has wide applicability for studying tissue distribution differences in the healthy and diseased brain.

  17. Structural angle and power images reveal interrelated gray and white matter abnormalities in schizophrenia.

    Science.gov (United States)

    Xu, Lai; Adali, Tülay; Schretlen, David; Pearlson, Godfrey; Calhoun, Vince D

    2012-01-01

    We present a feature extraction method to emphasize the interrelationship between gray and white matter and identify tissue distribution abnormalities in schizophrenia. This approach utilizes novel features called structural phase and magnitude images. The phase image indicates the relative contribution of gray and white matter, and the magnitude image reflects the overall tissue concentration. Three different analyses are applied to the phase and magnitude images obtained from 120 healthy controls and 120 schizophrenia patients. First, a single-subject subtraction analysis is computed for an initial evaluation. Second, we analyze the extracted features using voxel based morphometry (VBM) to detect voxelwise group differences. Third, source based morphometry (SBM) analysis was used to determine abnormalities in structural networks that co-vary in a similar way. Six networks were identified showing significantly lower white-to-gray matter in schizophrenia, including thalamus, right precentral-postcentral, left pre/post-central, parietal, right cuneus-frontal, and left cuneus-frontal sources. Interestingly, some networks look similar to functional patterns, such as sensory-motor and vision. Our findings demonstrate that structural phase and magnitude images can naturally and efficiently summarize the associated relationship between gray and white matter. Our approach has wide applicability for studying tissue distribution differences in the healthy and diseased brain.

  18. Direct Imaging of Charge Density Modulation in Switchable Two-Dimensional Electron Gas at the Oxide Hetero-Interfaces by Using Electron Bean Inline Holography

    Science.gov (United States)

    2015-08-16

    SUPPLEMENTARY NOTES 14. ABSTRACT The recent discovery of a two-dimensional electron gas (2DEG) at the interface between insulating perovskite ...3/10/2015 Abstract The recent discovery of a two-dimensional electron gas (2DEG) at the interface between insulating perovskite oxides SrTiO3...associated charge distributions in semiconductor materials, and therefore regarded as the only tool that can completely visualize the spatial

  19. Euler vector for search and retrieval of gray-tone images.

    Science.gov (United States)

    Bishnu, Arijit; Bhattacharya, Bhargab B; Kundu, Malay K; Murthy, C A; Acharya, Tinku

    2005-08-01

    A new combinatorial characterization of a gray-tone image called Euler Vector is proposed. The Euler number of a binary image is a well-known topological feature, which remains invariant under translation, rotation, scaling, and rubber-sheet transformation of the image. The Euler vector comprises a 4-tuple, where each element is an integer representing the Euler number of the partial binary image formed by the gray-code representation of the four most significant bit planes of the gray-tone image. Computation of Euler vector requires only integer and Boolean operations. The Euler vector is experimentally observed to be robust against noise and compression. For efficient image indexing, storage and retrieval from an image database using this vector, a bucket searching technique based on a simple modification of Kd-tree, is employed successfully. The Euler vector can also be used to perform an efficient four-dimensional range query. The set of retrieved images are finally ranked on the basis of Mahalanobis distance measure. Experiments are performed on the COIL database and results are reported. The retrieval success can be improved significantly by augmentiong the Euler vector by a few additional simple shape features. Since Euler vector can be computed very fast, the proposed technique is likely to find many applications to content-based image retrieval.

  20. Matching Two-dimensional Gel Electrophoresis' Spots

    DEFF Research Database (Denmark)

    Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza

    2012-01-01

    This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar......This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches...

  1. Generalizing the mean intercept length tensor for gray-level images.

    Science.gov (United States)

    Moreno, Rodrigo; Borga, Magnus; Smedby, Örjan

    2012-07-01

    The mean intercept length tensor is the most used technique to estimate microstructure orientation and anisotropy of trabecular bone. This paper proposes an efficient extension of this technique to gray-scale images based on a closed formulation of the mean intercept length tensor and a generalization using different angular convolution kernels. First, the extended Gaussian image is computed for the binary or gray-scale image. Second, the intercepts are computed for all possible orientations through an angular convolution with the half-cosine function. Finally, the tensor is computed by means of the covariance matrix. The complexity of the method isO(n + m) in contrast with O(nm) of traditional implementations, where n is the number of voxels in the image and m is the number of orientations used in the computations. The method is generalized by applying other angular convolution kernels instead of the half-cosine function. As a result, the anisotropy of the tensor can be controlled while keeping the eigenvectors intact. The proposed extension to gray-scale yields accurate results for reliable computations of the extended Gaussian image and, unlike the traditional methodology, is not affected by artifacts generated by discretizations during the sampling of different orientations. Experiments show that the computations on both binary and gray-scale images are correlated, and that computations in gray-scale are more robust, enabling the use of the mean intercept length tensor to clinical examinations of trabecular bone. The use of kernels based on the von Mises-Fisher distribution is promising as the anisotropy can be adjusted with a parameter in order to improve its power to predict mechanical properties of trabecular bone. © 2012 American Association of Physicists in Medicine.

  2. Texture Based Image Retrieval Using Framelet Transform–Gray Level Co-occurrence Matrix(GLCM

    Directory of Open Access Journals (Sweden)

    S. Sulochana

    2013-02-01

    Full Text Available This paper presents a novel content based image retrieval (CBIR system based on Framelet Transform combined with gray level co-occurrence matrix (GLCM.The proposed method is shift invariant which captured edge information more accurately than conventional transform domain methods as well as able to handle images of arbitrary size. Current system uses texture as a visual content for feature extraction. First Texture features are obtained by computing the energy, standard deviation and mean on each sub band of the Framelet transform decomposed image .Then a new method as a combination of the Framelet transform-Gray level co-occurrence matrix (GLCM is applied. The results of the proposed methods are compared with conventional methods. We have done the comparison of results of these two methods for image retrieval. Euclidean distance, Canberra distance, city black distance is used as similarity measure in the proposed CBIR system.

  3. A Novel Approach for Unsupervised Segmentation of Homogeneous Regions in Gray-scale Images

    Institute of Scientific and Technical Information of China (English)

    王郁中; 杨杰; 周大可; 郑元杰

    2004-01-01

    An improved approach for JSEG is presented for unsupervised segmentation of homogeneous regions in gray-scale images. Instead of intensity quantization, an automatic classification method based on scale space-based clustering is used for nonparametric clustering of image data set. Then EM algorithm with classification achieved by space-based classification scheme as initial data used to achieve Gaussian mixture modelling of image data set that is utilized for the calculation of soft J value. Original region growing algorithm is then used to segment the image based on the multiscale soft J-images. Experiments show that the new method can overcome the limitations of JSEG successfully.

  4. Gray-Scale Image Colorization Using Various Affinity Functions

    Directory of Open Access Journals (Sweden)

    Imron Rosyadi

    2012-02-01

    Full Text Available In this paper, we have proposed, implemented, and compared some affinity functions for an image colorization algorithm. The colorization qualityof the proposed affinityfunctions was just slightly behind the original functions, while one of the proposed functions performed faster than the original affinity function. We also implemented the colorization algorithm for coloring an Indonesian historical image.

  5. Assessment of left ventricular ejection fraction: comparison of two dimensional echocardiography, cardiac magnetic resonance imaging and 64-row multi-detector computed tomography

    Institute of Scientific and Technical Information of China (English)

    Chee Khoon LIEW; Kui Hian SIM; Rapaee ANNUAR; Tiong Kiam ONG; Sze Piaw CHIN; Tobias Seyfarth; Yean Yip FONG; Wei Ling CHAN; Choon Kiat ANG; Houng Bang LIEW

    2006-01-01

    Objectives To compare left ventricular ejection fraction (LVEF) determined from 64-row multi-detector computed tomography (64-row MDCT) with those determined from two dimensional echocardiography (2D echo) and cardiac magnetic resonance imaging (CMR). Methods Thirty-two patients with coronary artery disease underwent trans-thoracic 2D echo, CMR and contrast-enhanced 64-row MDCT for assessment of LVEF within 48 hours of each other. 64-row MDCT LVEF was derived using the Syngo Circulation software; CMR LVEF was by Area Length Ejection Fraction (ALEF) and Simpson method and 2D echo LVEF by Simpson method.Results The LVEF was 49.13 ± 15.91% by 2D echo, 50.72 ± 16.55% (ALEF method) and 47.65 ± 16.58%(Simpson method) by CMR and 50.00 ± 15.93% by 64-row MDCT. LVEF measurements by 64-row MDCT correlated well with LVEF measured with CMR using either the ALEF method (Pearson correlation r = 0.94, P <0.01) or Simpson method (r = 0.92, P<0.01). It also correlated well with LVEF measured using 2D echo (r = 0.80, P < 0.01). Conclusion LVEF measurements by 64-row MDCT correlated well with LVEF measured by CMR and 2D echo. The correlation between 64-row MDCT and CMR was better than the correlation between 2D echo with CMR. Standard data set from a 64-row MDCT coronary study can be reliably used to calculate the LVEF.

  6. Infiltration of CO2 into Water-Saturated Two-Dimensional Porous Micromodels: New Insight from Microscopic Particle Image Velocimetry (μPIV) Experiments

    Science.gov (United States)

    Kazemifar, F.; Blois, G.; Kyritsis, D. C.; Christensen, K. T.

    2013-12-01

    A novel experimental apparatus has been developed to study the interaction between liquid/supercritical CO2 and water in a two-dimensional porous micro-model. This flow process is very similar to what is encountered in many engineering applications such as sequestration of CO2 in geological formations (Carbon Capture and Sequestration, CCS) as well as enhanced oil recovery operations (EOR). Saline aquifers have very high potential for geological sequestration of CO2 based on several factors, including high capacity, economics and minimum environmental impact. Several CO2 injection and sequestration projects are currently in operation (e.g. Sleipner project in Norway), and numerous other projects are planned for the near future. While several studies exist on the large temporal- and spatial- scale effects of CO2 injection, the fluid-dynamic mechanisms at the pore-scale are largely unknown. In fact, recent studies suggest that such processes may be far more complex than previously addressed. CO2 and water/brine are immiscible, thus during the injection process of CO2 into a liquid-saturated porous structure, CO2 must displace the resident fluid. The lower viscosity and density of CO2 compared to water results in complex mechanisms of water displacement. While early studies focused on qualitative observations of fluid-fluid interactions, in this study, the microscopic particle image velocimetry (μPIV) technique is employed to quantify the flow fields within each fluid phase. The interface dynamics, migration and trapping mechanisms are of particular interest. In such flows, viscosity and interfacial tension are known as the main controlling parameters. In this regard, a challenging aspect of this work is that, in the vicinity of the critical point, these properties become very sensitive to changes in pressure and temperature. Additionally, despite the low Reynolds number of the flow, inertial effects are found to control the dynamics of flow patterns at the fluid

  7. Depth Map Generation Method of Two-dimensional Image Sequence%一种二维图像序列的深度图像生成方法

    Institute of Scientific and Technical Information of China (English)

    罗莎莎; 郭太良

    2012-01-01

    This paper proposes a depth map generation method based on motion object. First, the paper uses improved cumulative mean square deviation algorithm to extract background model, then background subtraction method is used to obtain motion object figure. After artificially drawing the depth map of the background model, with motion object figure of each frame, the depth maps of the image sequence are automatically synthesized, which can be directly used in two-dimensional (2D) to three-dimensional (3D) conversion. Experimental results show that compared with conventional depth map generation methods, depth map obtained by this method is true and reliable, thus more comfortable for 3D visualization.%针对二维图像序列提出一种基于运动对象的深度图像生成方法.采用改进的均方差累加算法提取背景模型,并利用背景差分法提取运动对象图形,将人工绘制的背景模型的深度图像,结合每帧运动对象图形深度赋值,自动合成用于二维视频到三维视频转换的图像序列的深度图像.实验结果证明,相对于传统的仅仅依靠计算机视觉获取深度图像的方法,它获得的深度图像,不仅画面的深度信息真实、可靠,而且转换后的三维场景更立体化.

  8. Left ventricular mechanics assessed by two-dimensional echocardiography and cardiac magnetic resonance imaging: comparison of high-resolution speckle tracking and feature tracking.

    Science.gov (United States)

    Aurich, Matthias; Keller, Marius; Greiner, Sebastian; Steen, Henning; Aus dem Siepen, Fabian; Riffel, Johannes; Katus, Hugo A; Buss, Sebastian J; Mereles, Derliz

    2016-12-01

    Assessment of left ventricular (LV) systolic function plays a central role in cardiac imaging. Calculation of ejection fraction (EF) is the current method of choice; however, its limited intermodal comparability represents a major drawback. The assessment of myocardial mechanics by strain imaging may better reflect the complex myocardial contractility. We aimed to evaluate different methods for quantification of LV strain on global and regional levels with a focus on the new non-proprietary feature tracking (FT) algorithm. Measurements of LV deformation were performed by means of high-resolution two-dimensional (2D) speckle tracking echocardiography (STE) and compared with values obtained by 2D feature tracking echocardiography (FT-E) and feature tracking cardiac magnetic resonance imaging (FT-CMR). Assessments with echocardiography started within 30 min after CMR examination to minimize time-dependent variations in myocardial function. Forty-seven patients were included. Assessments by STE were -15.7 ± 5.0% for global longitudinal strain (GLS), -14.6 ± 4.5% for global circumferential strain (GCS), and 21.6 ± 13.3% for global radial strain (GRS), while values obtained with FT-E were -13.1 ± 4.0, -13.6 ± 4.0, 20.3 ± 9.5, and with FT-CMR -15.0 ± 4.0, -16.9 ± 5.4, and 35.0 ± 10.8, respectively. Linear regression and the Bland-Altman analysis showed the best intramodal association for STE GLS and FT-E GLS (r = 0.88, bias = -2.7%, LOA = ±4.7%). The correlation for GCS and GRS was weaker, and for regional strain was poor. In contrast to EF, GLS showed a better intermodal correlation between echocardiography and CMR (r = 0.81 by speckle tracking, r = 0.8 by FT, and r = 0.78 by EF). In our study, measurement of global longitudinal LV strain using the new FT algorithm with CMR and echocardiography was comparable with measurements obtained by high-resolution STE. Compared with echocardiographic EF determination, FT-E GLS shows a better reproducibility and a better

  9. Steganalysis of LSB Embedded Images Using Gray Level Co-Occurrence Matrix

    OpenAIRE

    H.B.Kekre, A.A.Athawale, Sayli Anand Patki

    2011-01-01

    This paper proposes a steganalysis technique for both grayscale and colorimages. It uses the feature vectors derived from gray level co-occurrence matrix(GLCM) in spatial domain, which is sensitive to data embedding process. ThisGLCM matrix is derived from an image. Several combinations of diagonalelements of GLCM are considered as features. There is difference between thefeatures of stego and non-stego images and this characteristic is used forsteganalysis. Distance measures like Absolute di...

  10. Feasibility of non-invasive temperature estimation by the assessment of the average gray-level content of B-mode images.

    Science.gov (United States)

    Teixeira, C A; Alvarenga, A V; Cortela, G; von Krüger, M A; Pereira, W C A

    2014-08-01

    This paper assesses the potential of the average gray-level (AVGL) from ultrasonographic (B-mode) images to estimate temperature changes in time and space in a non-invasive way. Experiments were conducted involving a homogeneous bovine muscle sample, and temperature variations were induced by an automatic temperature regulated water bath, and by therapeutic ultrasound. B-mode images and temperatures were recorded simultaneously. After data collection, regions of interest (ROIs) were defined, and the average gray-level variation computed. For the selected ROIs, the AVGL-Temperature relation were determined and studied. Based on uniformly distributed image partitions, two-dimensional temperature maps were developed for homogeneous regions. The color-coded temperature estimates were first obtained from an AVGL-Temperature relation extracted from a specific partition (where temperature was independently measured by a thermocouple), and then extended to the other partitions. This procedure aimed to analyze the AVGL sensitivity to changes not only in time but also in space. Linear and quadratic relations were obtained depending on the heating modality. We found that the AVGL-Temperature relation is reproducible over successive heating and cooling cycles. One important result was that the AVGL-Temperature relations extracted from one region might be used to estimate temperature in other regions (errors inferior to 0.5 °C) when therapeutic ultrasound was applied as a heating source. Based on this result, two-dimensional temperature maps were developed when the samples were heated in the water bath and also by therapeutic ultrasound. The maps were obtained based on a linear relation for the water bath heating, and based on a quadratic model for the therapeutic ultrasound heating. The maps for the water bath experiment reproduce an acceptable heating/cooling pattern, and for the therapeutic ultrasound heating experiment, the maps seem to reproduce temperature profiles

  11. The convolution theorem for two-dimensional continuous wavelet transform

    Institute of Scientific and Technical Information of China (English)

    ZHANG CHI

    2013-01-01

    In this paper , application of two -dimensional continuous wavelet transform to image processes is studied. We first show that the convolution and correlation of two continuous wavelets satisfy the required admissibility and regularity conditions ,and then we derive the convolution and correlation theorem for two-dimensional continuous wavelet transform. Finally, we present numerical example showing the usefulness of applying the convolution theorem for two -dimensional continuous wavelet transform to perform image restoration in the presence of additive noise.

  12. Multifractal analysis of 2D gray soil images

    Science.gov (United States)

    González-Torres, Ivan; Losada, Juan Carlos; Heck, Richard; Tarquis, Ana M.

    2015-04-01

    Soil structure, understood as the spatial arrangement of soil pores, is one of the key factors in soil modelling processes. Geometric properties of individual and interpretation of the morphological parameters of pores can be estimated from thin sections or 3D Computed Tomography images (Tarquis et al., 2003), but there is no satisfactory method to binarized these images and quantify the complexity of their spatial arrangement (Tarquis et al., 2008, Tarquis et al., 2009; Baveye et al., 2010). The objective of this work was to apply a multifractal technique, their singularities (α) and f(α) spectra, to quantify it without applying any threshold (Gónzalez-Torres, 2014). Intact soil samples were collected from four horizons of an Argisol, formed on the Tertiary Barreiras group of formations in Pernambuco state, Brazil (Itapirema Experimental Station). The natural vegetation of the region is tropical, coastal rainforest. From each horizon, showing different porosities and spatial arrangements, three adjacent samples were taken having a set of twelve samples. The intact soil samples were imaged using an EVS (now GE Medical. London, Canada) MS-8 MicroCT scanner with 45 μm pixel-1 resolution (256x256 pixels). Though some samples required paring to fit the 64 mm diameter imaging tubes, field orientation was maintained. References Baveye, P.C., M. Laba, W. Otten, L. Bouckaert, P. Dello, R.R. Goswami, D. Grinev, A. Houston, Yaoping Hu, Jianli Liu, S. Mooney, R. Pajor, S. Sleutel, A. Tarquis, Wei Wang, Qiao Wei, Mehmet Sezgin. Observer-dependent variability of the thresholding step in the quantitative analysis of soil images and X-ray microtomography data. Geoderma, 157, 51-63, 2010. González-Torres, Iván. Theory and application of multifractal analysis methods in images for the study of soil structure. Master thesis, UPM, 2014. Tarquis, A.M., R.J. Heck, J.B. Grau; J. Fabregat, M.E. Sanchez and J.M. Antón. Influence of Thresholding in Mass and Entropy Dimension of 3-D

  13. Gray Cerebrovascular Image Skeleton Extraction Algorithm Using Level Set Model

    Directory of Open Access Journals (Sweden)

    Jian Wu

    2010-06-01

    Full Text Available The ambiguity and complexity of medical cerebrovascular image makes the skeleton gained by conventional skeleton algorithm discontinuous, which is sensitive at the weak edges, with poor robustness and too many burrs. This paper proposes a cerebrovascular image skeleton extraction algorithm based on Level Set model, using Euclidean distance field and improved gradient vector flow to obtain two different energy functions. The first energy function controls the  obtain of topological nodes for the beginning of skeleton curve. The second energy function controls the extraction of skeleton surface. This algorithm avoids the locating and classifying of the skeleton connection points which guide the skeleton extraction. Because all its parameters are gotten by the analysis and reasoning, no artificial interference is needed.

  14. Hybrid coding for split gray values in radiological image compression

    Science.gov (United States)

    Lo, Shih-Chung B.; Krasner, Brian; Mun, Seong K.; Horii, Steven C.

    1992-05-01

    Digital techniques are used more often than ever in a variety of fields. Medical information management is one of the largest digital technology applications. It is desirable to have both a large data storage resource and extremely fast data transmission channels for communication. On the other hand, it is also essential to compress these data into an efficient form for storage and transmission. A variety of data compression techniques have been developed to tackle a diversity of situations. A digital value decomposition method using a splitting and remapping method has recently been proposed for image data compression. This method attempts to employ an error-free compression for one part of the digital value containing highly significant value and uses another method for the second part of the digital value. We have reported that the effect of this method is substantial for the vector quantization and other spatial encoding techniques. In conjunction with DCT type coding, however, the splitting method only showed a limited improvement when compared to the nonsplitting method. With the latter approach, we used a nonoptimized method for the images possessing only the top three-most-significant- bit value (3MSBV) and produced a compression ratio of approximately 10:1. Since the 3MSB images are highly correlated and the same values tend to aggregate together, the use of area or contour coding was investigated. In our experiment, we obtained an average error-free compression ratio of 30:1 and 12:1 for 3MSB and 4MSB images, respectively, with the alternate value contour coding. With this technique, we clearly verified that the splitting method is superior to the nonsplitting method for finely digitized radiographs.

  15. SAR River Image Segmentation Based on Reciprocal Gray Entropy and Improved Chan-Vese Model

    Directory of Open Access Journals (Sweden)

    WU Shihua

    2015-11-01

    Full Text Available To further improve the accuracy and speed of river segmentation on synthetic aperture radar(SAR images, a segmentation method is proposed, which is based on improved Chan-Vese(CV model combining with reciprocal gray entropy multi-threshold selection optimized by artificial bee colony algorithm. Considering the uniformity of the gray level within river object cluster and background cluster, a coarse river image segmentation is made by using the multi-threshold selection algorithm based on reciprocal gray entropy and artificial bee colony optimization; Contrapose the low convergence speed and the sensitivity to initial conditions of basic CV model, the Dirac function is replaced with the image edge intensity and the coarse segmentation results serve as the initial condition of improved CV model which is utilized to make a fine segmentation for the river image. A large number of experimental results show that, the proposed segmentation method needs not set initial conditions and has high running speed as well as segmentation accuracy.

  16. An Automatic Eye Detection Method for Gray Intensity Facial Images

    Directory of Open Access Journals (Sweden)

    M Hassaballah

    2011-07-01

    Full Text Available Eyes are the most salient and stable features in the human face, and hence automatic extraction or detection of eyes is often considered as the most important step in many applications, such as face identification and recognition. This paper presents a method for eye detection of still grayscale images. The method is based on two facts: eye regions exhibit unpredictable local intensity, therefore entropy in eye regions is high and the center of eye (iris is too dark circle (low intensity compared to the neighboring regions. A score based on the entropy of eye and darkness of iris is used to detect eye center coordinates. Experimental results on two databases; namely, FERET with variations in views and BioID with variations in gaze directions and uncontrolled conditions show that the proposed method is robust against gaze direction, variations in views and variety of illumination. It can achieve a correct detection rate of 97.8% and 94.3% on a set containing 2500 images of FERET and BioID databases respectively. Moreover, in the cases with glasses and severe conditions, the performance is still acceptable.

  17. A novel quantum LSB-based steganography method using the Gray code for colored quantum images

    Science.gov (United States)

    Heidari, Shahrokh; Farzadnia, Ehsan

    2017-10-01

    As one of the prevalent data-hiding techniques, steganography is defined as the act of concealing secret information in a cover multimedia encompassing text, image, video and audio, imperceptibly, in order to perform interaction between the sender and the receiver in which nobody except the receiver can figure out the secret data. In this approach a quantum LSB-based steganography method utilizing the Gray code for quantum RGB images is investigated. This method uses the Gray code to accommodate two secret qubits in 3 LSBs of each pixel simultaneously according to reference tables. Experimental consequences which are analyzed in MATLAB environment, exhibit that the present schema shows good performance and also it is more secure and applicable than the previous one currently found in the literature.

  18. QR code based noise-free optical encryption and decryption of a gray scale image

    Science.gov (United States)

    Jiao, Shuming; Zou, Wenbin; Li, Xia

    2017-03-01

    In optical encryption systems, speckle noise is one major challenge in obtaining high quality decrypted images. This problem can be addressed by employing a QR code based noise-free scheme. Previous works have been conducted for optically encrypting a few characters or a short expression employing QR codes. This paper proposes a practical scheme for optically encrypting and decrypting a gray-scale image based on QR codes for the first time. The proposed scheme is compatible with common QR code generators and readers. Numerical simulation results reveal the proposed method can encrypt and decrypt an input image correctly.

  19. The FBI wavelet/scalar quantization standard for gray-scale fingerprint image compression

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, J.N.; Brislawn, C.M. [Los Alamos National Lab., NM (United States); Hopper, T. [Federal Bureau of Investigation, Washington, DC (United States)

    1993-05-01

    The FBI has recently adopted a standard for the compression of digitized 8-bit gray-scale fingerprint images. The standard is based on scalar quantization of a 64-subband discrete wavelet transform decomposition of the images, followed by Huffman coding. Novel features of the algorithm include the use of symmetric boundary conditions for transforming finite-length signals and a subband decomposition tailored for fingerprint images scanned at 500 dpi. The standard is intended for use in conjunction with ANSI/NBS-CLS 1-1993, American National Standard Data Format for the Interchange of Fingerprint Information, and the FBI`s Integrated Automated Fingerprint Identification System.

  20. The FBI wavelet/scalar quantization standard for gray-scale fingerprint image compression

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, J.N.; Brislawn, C.M. (Los Alamos National Lab., NM (United States)); Hopper, T. (Federal Bureau of Investigation, Washington, DC (United States))

    1993-01-01

    The FBI has recently adopted a standard for the compression of digitized 8-bit gray-scale fingerprint images. The standard is based on scalar quantization of a 64-subband discrete wavelet transform decomposition of the images, followed by Huffman coding. Novel features of the algorithm include the use of symmetric boundary conditions for transforming finite-length signals and a subband decomposition tailored for fingerprint images scanned at 500 dpi. The standard is intended for use in conjunction with ANSI/NBS-CLS 1-1993, American National Standard Data Format for the Interchange of Fingerprint Information, and the FBI's Integrated Automated Fingerprint Identification System.

  1. Recovering Root System Traits Using Image Analysis Exemplified by Two-Dimensional Neutron Radiography Images of Lupine1[C][W][OPEN

    Science.gov (United States)

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

    2014-01-01

    Root system traits are important in view of current challenges such as sustainable crop production with reduced fertilizer input or in resource-limited environments. We present a novel approach for recovering root architectural parameters based on image-analysis techniques. It is based on a graph representation of the segmented and skeletonized image of the root system, where individual roots are tracked in a fully automated way. Using a dynamic root architecture model for deciding whether a specific path in the graph is likely to represent a root helps to distinguish root overlaps from branches and favors the analysis of root development over a sequence of images. After the root tracking step, global traits such as topological characteristics as well as root architectural parameters are computed. Analysis of neutron radiographic root system images of lupine (Lupinus albus) grown in mesocosms filled with sandy soil results in a set of root architectural parameters. They are used to simulate the dynamic development of the root system and to compute the corresponding root length densities in the mesocosm. The graph representation of the root system provides global information about connectivity inside the graph. The underlying root growth model helps to determine which path inside the graph is most likely for a given root. This facilitates the systematic investigation of root architectural traits, in particular with respect to the parameterization of dynamic root architecture models. PMID:24218493

  2. Two-dimensional fluorescence-detected coherent spectroscopy with absolute phasing by confocal imaging of a dynamic grating and 27-step phase-cycling

    Energy Technology Data Exchange (ETDEWEB)

    De, Arijit K., E-mail: akde@lbl.gov; Fleming, Graham R., E-mail: grfleming@lbl.gov [Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94702 (United States); Department of Chemistry, University of California at Berkeley, Berkeley, California 94702 (United States); Monahan, Daniele; Dawlaty, Jahan M. [Department of Chemistry, University of California at Berkeley, Berkeley, California 94702 (United States)

    2014-05-21

    We present a novel experimental scheme for two-dimensional fluorescence-detected coherent spectroscopy (2D-FDCS) using a non-collinear beam geometry with the aid of “confocal imaging” of dynamic (population) grating and 27-step phase-cycling to extract the signal. This arrangement obviates the need for distinct experimental designs for previously developed transmission detected non-collinear two-dimensional coherent spectroscopy (2D-CS) and collinear 2D-FDCS. We also describe a novel method for absolute phasing of the 2D spectrum. We apply this method to record 2D spectra of a fluorescent dye in solution at room temperature and observe “spectral diffusion.”.

  3. Hand Vein Images Enhancement Based on Local Gray-level Information Histogram

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2015-06-01

    Full Text Available Based on the Histogram equalization theory, this paper presents a novel concept of histogram to realize the contrast enhancement of hand vein images, avoiding the lost of topological vein structure or importing the fake vein information. Firstly, we propose the concept of gray-level information histogram, the fundamental characteristic of which is that the amplitudes of the components can objectively reflect the contribution of the gray levels and information to the representation of image information. Then, we propose the histogram equalization method that is composed of an automatic histogram separation module and an intensity transformation module, and the histogram separation module is a combination of the proposed prompt multiple threshold procedure and an optimum peak signal-to-noise (PSNR calculation to separate the histogram into small-scale detail, the use of the intensity transformation module can enhance the vein images with vein topological structure and gray information preservation for each generated sub-histogram. Experimental results show that the proposed method can achieve extremely good contrast enhancement effect.

  4. AN ADAPTIVE DIGITAL IMAGE WATERMARK ALGORITHM BASED ON GRAY-SCALE MORPHOLOGY

    Institute of Scientific and Technical Information of China (English)

    Tong Ming; Hu Jia; Ji Hongbing

    2009-01-01

    An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper.The embedded strategies include:The algorithm seeks and extracts adaptively the image strong texture regions.The algorithm maps the image strong texture region to the wavelet tree structures,and embeds adaptively watermark into the wavelet coefficients corresponding to the image's strong texture regions.According to the visual masking features,the algorithm adjusts adaptively the watermark-embedding intensity.Experimental results show the algorithm is robust to compression,filtering,noise as well as strong shear attacks.The algorithm is blind watermark scheme.The image strong texture region extraction method based on morphology in this algorithm is simple and effective and adaptive to various images.

  5. Combining depth and gray images for fast 3D object recognition

    Science.gov (United States)

    Pan, Wang; Zhu, Feng; Hao, Yingming

    2016-10-01

    Reliable and stable visual perception systems are needed for humanoid robotic assistants to perform complex grasping and manipulation tasks. The recognition of the object and its precise 6D pose are required. This paper addresses the challenge of detecting and positioning a textureless known object, by estimating its complete 6D pose in cluttered scenes. A 3D perception system is proposed in this paper, which can robustly recognize CAD models in cluttered scenes for the purpose of grasping with a mobile manipulator. Our approach uses a powerful combination of two different camera technologies, Time-Of-Flight (TOF) and RGB, to segment the scene and extract objects. Combining the depth image and gray image to recognize instances of a 3D object in the world and estimate their 3D poses. The full pose estimation process is based on depth images segmentation and an efficient shape-based matching. At first, the depth image is used to separate the supporting plane of objects from the cluttered background. Thus, cluttered backgrounds are circumvented and the search space is extremely reduced. And a hierarchical model based on the geometry information of a priori CAD model of the object is generated in the offline stage. Then using the hierarchical model we perform a shape-based matching in 2D gray images. Finally, we validate the proposed method in a number of experiments. The results show that utilizing depth and gray images together can reach the demand of a time-critical application and reduce the error rate of object recognition significantly.

  6. Gray matter involvement in patients with multiple sclerosis as shown by magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Reshiana Rumzan; CHEN Xuan; LI Yong-mei

    2012-01-01

    Objective To summarize the main findings seen on conventional and advanced magnetic resonance imaging (MRI)used to assess gray matter (GM) involvement in patients with multiple sclerosis (MS).Data sources The data used in this review were obtained mainly from studies reported in the PubMed database using the terms of multiple sclerosis,gray matter,magnetic resonance imaging.Study selection Relevant literatures on studies of GM involvement in MS patients were identified,retrieved and reviewed.Results MS is the most common chronic,disabling central nervous system disease in young adults.Although traditional thinking has considered MS to be a chronic inflammatory demyelinating condition affecting solely the white matter (WM) of the central nervous system,over the last few years it has been shown that GM pathology is also common and extensive.GM demyelinating lesions can not only be found in the cerebral cortex but also in the deep gray nuclei.Apart from focal demyelinatad lesions,diffuse neuronal loss and atrophy is also present in the GM of MS patients.Conclusions The widespread use of conventional and quantitative MRI based techniques in MS has led to an improved understanding of the mechanisms underlying the inflammatory and neurodegenerative processes of the disease.However,more researches are needed to unravel GM pathology in MS patients,which at present remains enigmatic.

  7. Edge Detection in Gray Level Images based on the Shannon Entropy

    Directory of Open Access Journals (Sweden)

    Baljit Singh

    2008-01-01

    Full Text Available Most of the classical mathematical methods for edge detection based on the derivative of the pixels of the original image are Gradient operators, Laplacian and Laplacian of Gaussian operators. Gradient based edge detection methods, such as Roberts, Sobel and Prewitts, have used two 2-D linear filters to process vertical edges and horizontal edges separately to approximate first-order derivative of pixel values of the image. The Laplacian edge detection method has used a 2-D linear filter to approximate second-order derivative of pixel values of the image. Major drawback of second-order derivative approach is that the response at and around the isolated pixel is much stronger. In this research study, a novel approach utilizing Shannon entropy other than the evaluation of derivates of the image in detecting edges in gray level images has been proposed. The proposed approach solves this problem at some extent. In the proposed method, we have used a suitable threshold value to segment the image and achieve the binary image. After this the proposed edge detector is introduced to detect and locate the edges in the image. A standard test image is used to compare the results of the proposed edge detector with the Laplacian of Gaussian edge detector operator. In order to validate the results, seven different kinds of test images are considered to examine the versatility of the proposed edge detector. It has been observed that the proposed edge detector works effectively for different gray scale digital images. The results of this study were quite promising.

  8. Contribution to the design of two-dimensional non-recursive filters using the techniques of artificial intelligence: application to image processing

    OpenAIRE

    Boudjelaba, Kamal

    2012-01-01

    Journée des Jeunes Chercheurs du laboratoire Prisme, 2 Juillet 2012; -This paper presents an objective and comparative study of evolutionary algorithms applied to the design of two-dimensional (2-D) FIR filters. The design of 2-D FIR filters can be formulated as a non-linear optimization problem. We explore several stochastic methodologies capable of handling large spaces. We finally propose a new genetic algorithm in which some concepts are introduced to optimize the trade-off between divers...

  9. Print image sharpness analysis based on gray-level co-occurrence matrices

    Science.gov (United States)

    Zhang, Lin; Zhang, Meiyun; Wu, Yangyu

    2010-08-01

    A novel measure is presented to quantify print image sharpness. Nine texture features of gray level co-occurrence matrices (GLCM) were calculated from the print images respectively which were blurred by Gaussian blurs filter with different radius ranging from 0 to 8 pixels in steps of 2. Experiments were performed on these images with different GLCM distance d (2, 4, 6, 8,10 pixels) and orientation θ (0°, 45°, 90°, 135°) under the constant window size (64 pixels). Furthermore, the correlation matrix of texture features was calculated to judge which texture features can be chosen to assess sharpness most. The test results show contrast and energy provide the most unique information of print image sharpness. And the distance d of GLCM can be determined to be 6 pixels and the different orientation θ has little effect on the trends. The method is reliable and extends GLCM with the sharpness evaluation of variable size, oriented print image.

  10. Two-dimensional liquid chromatography

    DEFF Research Database (Denmark)

    Græsbøll, Rune

    of this thesis is on online comprehensive two-dimensional liquid chromatography (online LC×LC) with reverse phase in both dimensions (online RP×RP). Since online RP×RP has not been attempted before within this research group, a significant part of this thesis consists of knowledge and experience gained...

  11. Histogram and gray level co-occurrence matrix on gray-scale ultrasound images for diagnosing lymphocytic thyroiditis.

    Science.gov (United States)

    Shin, Young Gyung; Yoo, Jaeheung; Kwon, Hyeong Ju; Hong, Jung Hwa; Lee, Hye Sun; Yoon, Jung Hyun; Kim, Eun-Kyung; Moon, Hee Jung; Han, Kyunghwa; Kwak, Jin Young

    2016-08-01

    The objective of the study was to evaluate whether texture analysis using histogram and gray level co-occurrence matrix (GLCM) parameters can help clinicians diagnose lymphocytic thyroiditis (LT) and differentiate LT according to pathologic grade. The background thyroid pathology of 441 patients was classified into no evidence of LT, chronic LT (CLT), and Hashimoto's thyroiditis (HT). Histogram and GLCM parameters were extracted from the regions of interest on ultrasound. The diagnostic performances of the parameters for diagnosing and differentiating LT were calculated. Of the histogram and GLCM parameters, the mean on histogram had the highest Az (0.63) and VUS (0.303). As the degrees of LT increased, the mean decreased and the standard deviation and entropy increased. The mean on histogram from gray-scale ultrasound showed the best diagnostic performance as a single parameter in differentiating LT according to pathologic grade as well as in diagnosing LT.

  12. Salient Object Extraction Using Multilevel Gray Scale Quantization and Image Smoothing

    Institute of Scientific and Technical Information of China (English)

    Akram Tallha; HaiderAli Sajjad

    2013-01-01

    A novel multi level image segmentation methodology is been proposed with the aim of extracting the salient object,keeping in view,only a small part of the visual scene undergoes attention and reaches the level of awareness while rest of details are futile.Taking advantage of multilevel gray scale quantization,image prominent object is separated from background,keeping in view the fact; salient object is having high contrast as compared to the background.The inutile fragments were removed using morphological operations of opening and closing and making the image smoothened with Gaussian filter.The optimum threshold is selected for the binary conversion and final extrication of the salient object from the image.The experimental data indicates that hybrid approach leads to improved segmentation with the apparent assertion of prime object extraction.

  13. A two-dimensional Dirac fermion microscope

    Science.gov (United States)

    Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads

    2017-06-01

    The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.

  14. A two-dimensional Dirac fermion microscope.

    Science.gov (United States)

    Bøggild, Peter; Caridad, José M; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads

    2017-06-09

    The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.

  15. Coarse Level Sketch Based Image Retreival Using Gray Level CoOccurance Matrix

    Directory of Open Access Journals (Sweden)

    D. Arundeepthi,

    2012-09-01

    Full Text Available This paper proposes a method of Content based image retrieval (CBIR using sketches, which is one of the most popular, rising research areas of the digital image processing. Most of the available image search tools, such as Google Images and Yahoo! Image search, are based on textual annotation of images. In these tools, images are manually annotated with keywords and then retrieved using text-based search methods. The performances of these systems are not satisfactory. The goal of CBIR is to extract visual content of an image automatically, like color, texture, or shape. The proposed method used to introduce the design and the creation of CBIR systems, which is based on a free hand sketch (Sketch based image retrieval – SBIR. In this method, we are using texture as feature for image retrieval. The texture features are obtained by using gray-level co-occurrence matrix (GLCM.This process can be used as coarse level in hierarchical CBIR that reduces the database size from very large set to a small one. This tiny database can further be scrutinized rigorously using the wavelets, edge detection, etc. The sketch based system allows users an intuitive access to search-tools. This process can be implemented in MATLAB simulation.

  16. Two dimensional unstable scar statistics.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Kotulski, Joseph Daniel; Lee, Kelvin S. H. (ITT Industries/AES Los Angeles, CA)

    2006-12-01

    This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.

  17. Two-Dimensional Vernier Scale

    Science.gov (United States)

    Juday, Richard D.

    1992-01-01

    Modified vernier scale gives accurate two-dimensional coordinates from maps, drawings, or cathode-ray-tube displays. Movable circular overlay rests on fixed rectangular-grid overlay. Pitch of circles nine-tenths that of grid and, for greatest accuracy, radii of circles large compared with pitch of grid. Scale enables user to interpolate between finest divisions of regularly spaced rule simply by observing which mark on auxiliary vernier rule aligns with mark on primary rule.

  18. A Simple and Robust Gray Image Encryption Scheme Using Chaotic Logistic Map and Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Adelaïde Nicole Kengnou Telem

    2014-01-01

    Full Text Available A robust gray image encryption scheme using chaotic logistic map and artificial neural network (ANN is introduced. In the proposed method, an external secret key is used to derive the initial conditions for the logistic chaotic maps which are employed to generate weights and biases matrices of the multilayer perceptron (MLP. During the learning process with the backpropagation algorithm, ANN determines the weight matrix of the connections. The plain image is divided into four subimages which are used for the first diffusion stage. The subimages obtained previously are divided into the square subimage blocks. In the next stage, different initial conditions are employed to generate a key stream which will be used for permutation and diffusion of the subimage blocks. Some security analyses such as entropy analysis, statistical analysis, and key sensitivity analysis are given to demonstrate the key space of the proposed algorithm which is large enough to make brute force attacks infeasible. Computing validation using experimental data with several gray images has been carried out with detailed numerical analysis, in order to validate the high security of the proposed encryption scheme.

  19. The gray-scale ink-jet printer: value in making hard copies of digital images.

    Science.gov (United States)

    Combs, M J; Snell, J; Cail, W S; Maier, T; Buck, D A

    1995-01-01

    Referring physicians often are supplied with copies of images to illustrate a report of the findings of a radiologic study or so that the radiologist can retain the original images. The increasing costs of production, film, and recovery of chemicals have enhanced the requirement for a clean, low-cost dry printing process. An ink-jet gray-scale paper printer (Unitone, Scitex Medical Systems, Bedford, MA) can print high-quality (300 dots per inch [dpi]) images with an effective 10-bit gray scale range by using the Hertz continuous ink-jet method [1-3], which does not require the use of a darkroom or hazardous chemicals. Several types of media (matte paper, glossy paper, transparency film) with a printing area of 26.9 x 43.7 cm (10.6 x 17.4 inches) may be used. The consumables are approximately 50-70% less expensive than the cost of silver halide film, providing a cost advantage over film for referral and archival copies. The results of an initial evaluation of the ink-jet printer at our institution are reported here.

  20. FACE RECOGNITION USING TWO DIMENSIONAL LAPLACIAN EIGENMAP

    Institute of Scientific and Technical Information of China (English)

    Chen Jiangfeng; Yuan Baozong; Pei Bingnan

    2008-01-01

    Recently,some research efforts have shown that face images possibly reside on a nonlinear sub-manifold. Though Laplacianfaces method considered the manifold structures of the face images,it has limits to solve face recognition problem. This paper proposes a new feature extraction method,Two Dimensional Laplacian EigenMap (2DLEM),which especially considers the manifold structures of the face images,and extracts the proper features from face image matrix directly by using a linear transformation. As opposed to Laplacianfaces,2DLEM extracts features directly from 2D images without a vectorization preprocessing. To test 2DLEM and evaluate its performance,a series of ex-periments are performed on the ORL database and the Yale database. Moreover,several experiments are performed to compare the performance of three 2D methods. The experiments show that 2DLEM achieves the best performance.

  1. Data analysis results of the second sea trial of ambient noise imaging with acoustic lens in 2014: Two-dimensional target images affected by direction of field of view and spatial noise distribution

    Science.gov (United States)

    Mori, Kazuyoshi; Ogasawara, Hanako; Tsuchiya, Takenobu; Endoh, Nobuyuki

    2016-07-01

    An aspherical lens with an aperture diameter of 1.0 m has been designed and fabricated to develop a prototype system for ambient noise imaging (ANI). A sea trial of silent target detection using the prototype ANI system was conducted under only natural ocean ambient noise at Uchiura Bay in November 2010. It was verified that targets are successfully detected under natural ocean ambient noise, mainly generated by snapping shrimps. Recently, we have built a second prototype ANI system using an acoustic lens with a two-dimensional (2D) receiver array with 127 elements corresponding to a field of view (FOV) spanning 15° horizontally by 9° vertically. In this study, we investigated the effects of the direction of the FOV and the spatial noise distribution on the 2D target image obtained by ANI. Here, the noise sources in front of the target are called “front light”, and those at the rear of the target are called “back light”. The second sea trial was conducted to image targets arranged in the FOV and measure the positions of noise sources at Uchiura Bay in November 10-14, 2014. For front light, the pixel values in the on-target directions were greater than those in other directions owing to the dominant target scatterings. Reversely, for back light, the pixel values in the on-target directions were lower than those in other directions owing to the dominant direct noises such as “silhouette”.

  2. Steganography Using Adaptive Pixel Value Differencing(APVD) of Gray Images Through Exclusion of Overflow/Underflow

    CERN Document Server

    Mandal, J K

    2012-01-01

    In a gray scale image the pixel value ranges from 0 to 255. But when we use pixel-value differencing (pvd) method as image steganographic scheme, the pixel values in the stego-image may exceed gray scale range. An adaptive steganography based on modified pixel-value differencing through management of pixel values within the range of gray scale has been proposed in this paper. PVD method is used and check whether the pixel value exceeds the range on embedding. Positions where the pixel exceeds boundary has been marked and a delicate handle is used to keep the value within the range. From the experimental it is seen that the results obtained in proposed method provides with identical payload and visual fidelity of stego-image compared to the pvd method.

  3. A Study on the Temperature Correlation of B-mode Ultrasonic Image Gray for Noninvasive Temperature Monitoring in Hyperthermia

    Institute of Scientific and Technical Information of China (English)

    WU Shui-cai; Ren Xin-ying; Bai Yan-ping; Zeng Yi

    2006-01-01

    This paper deals with the temperature correlation of gray scale of Bmode ultrasound image from heated tissue. In this study, many in-vitro fresh pig livers are heated in a temperature range from 28℃ to 45℃, from which a series of B-mode ultrasonic images of livers were obtained. The gray-value is evaluated from the ultrasound images respectively. A correlation of the mean gray value of the selected regions (12×12 pixels) in B-mode ultrasonic images of liver and its temperature was pointed out. And the experiment results agreed the evaluation well. And it is possible to monitor the tissue temperature changing in hyperthermia using this correlation.

  4. Comparison of right ventricular contractile abnormalities in hypertrophic cardiomyopathy versus hypertensive heart disease using two dimensional strain imaging: a cross-sectional study.

    Science.gov (United States)

    Afonso, Luis; Briasoulis, Alex; Mahajan, Nitin; Kondur, Ashok; Siddiqui, Fayez; Siddiqui, Sabeeh; Alesh, Issa; Cardozo, Shaun; Kottam, Anupama

    2015-12-01

    Hypertrophic cardiomyopathy (HCM) affects the right ventricle (RV) because of the anatomically hypertrophied septum and plausibly by extension of the myopathic process to the RV. We sought to investigate RV strain in patients with left ventricular hypertrophy secondary to either HCM or hypertension (H-LVH). Our cross-sectional study included 32 patients with HCM, 21 patients with H-LVH, and 11 healthy subjects, who were evaluated with transthoracic echocardiography. Using a dedicated software package, bi-dimensional acquisitions were analyzed to measure segmental longitudinal strain in apical views. Right ventricular global longitudinal strain (GLS) was calculated by averaging septal and right free wall strains. The HCM and H-LVH groups were comparable for age and demographic characteristics. Right ventricular tricuspid annular plane systolic excursion was not significantly different between HCM and H-LVH subjects. Moreover, RV GLS, septal and lateral RV myocardial strain were significantly impaired in patients with HCM (all p 14.9% differentiated HCM and H-LVH with a 90% sensitivity and a 95% specificity (p < 0.001). RV strain parameters are impaired in patients with HCM. Assessment of two-dimensional RV strain parameters could help differentiate between HCM and H-LVH.

  5. Two-dimensional liquid chromatography

    DEFF Research Database (Denmark)

    Græsbøll, Rune

    Two-dimensional liquid chromatography has received increasing interest due to the rise in demand for analysis of complex chemical mixtures. Separation of complex mixtures is hard to achieve as a simple consequence of the sheer number of analytes, as these samples might contain hundreds or even...... dimensions. As a consequence of the conclusions made within this thesis, the research group has, for the time being, decided against further development of online LC×LC systems, since it was not deemed ideal for the intended application, the analysis of the polar fraction of oil. Trap-and...

  6. A Novel Steganography Method for Hiding BW Images into Gray Bitmap Images via k-Modulus Method

    Directory of Open Access Journals (Sweden)

    Firas A. Jassim

    2013-09-01

    Full Text Available This paper is to create a pragmatic steganographic implementation to hide black and white image which is known as stego image inside another gray bitmap image that known as cover image. First of all, the proposed technique uses k-Modulus Method (K-MM to convert all pixels within the cover image into multiples of positive integer named k. Since the black and white images can be represented using binary representation, i.e. 0 or 1. Then, in this article, the suitable value for the positive integer k is two. Therefore, each pixel inside the cover image is divisible by two and this produces a reminder which is either 0 or 1. Subsequently, the black and white representation of the stego image could be hidden inside the cover image. The ocular differences between the cover image before and after adding the stego image are insignificant. The experimental results show that the PSNR values for the cover image are very high with very small Mean Square Error.

  7. Efficient gray-level digital image watermarking based on vector quantization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Digital watermarking has been presented as a new method for copyright protection by embedding a se cret signal in a digital image or video sequence. Common digital image watermarking techniques are based on the concept of spread-spectrum communications, which can be classified in two catalogues: spatial-domain and transform-domain based. Most of transform-domain watermarking methods are based on discrete cosine trans forms (DCT) and robust to JPEG lossy compression. Recently, digital image watermarking based on another important lossy compression technique, vector quantization (VQ), has been presented, which carries water mark information by codeword indices. It is secret and efficient, and is robust to VQ compression with the same codebook. However, the embedded information is less and the extraction process requires the original image.This paper presents a more efficient VQ-based image watermarking method, which can embed a large gray-level watermark into the original image with less extra distortion and perform the watermark extraction without the original image. In addition, the proposed watermarking algorithm is very secret because two keys are required for watermark extraction. Experimental results demonstrate the effectiveness of the proposed technique.

  8. Two-dimensional capillary origami

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, N.D., E-mail: nbrubaker@math.arizona.edu; Lega, J., E-mail: lega@math.arizona.edu

    2016-01-08

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.

  9. 蜂群优化的二维非对称 Tsallis 交叉熵图像阈值选取%Two-dimensional asymmte ric tsallis cross entropy image threshold selection using bee colony optimization

    Institute of Scientific and Technical Information of China (English)

    吴一全; 王凯; 曹鹏祥

    2015-01-01

    Cross entropy can measure the difference between the original image and its segmentation result .Comparedwith Shannon cross entropy , Tsallis cross entropy, in which a parameter q is introduced, provides flexibilityand universality for the segmentation of image threshold .The asymmetric Tsallis cross entropy has more concise expressionform.Therefore, a method of threshold selection is proposed based on the two -dimensional asymmetric Tsalliscross entropy using bee colony optimization.Firstly, the asymmetric Tsallis cross entropy is introduced and thethreshold selection formulae based on the two -dimensional asymmetric Tsallis cross entropy are derived .Recursivealgorithms are used to calculate the intermediate variables involved in criterion function for threshold selection and alookup table is built to eliminate the redundant operations .The optimal two-dimensional threshold is searched by thebee colony algorithm.A large number of experiment results showed that the proposed method is greatly improved interms of subjective visual effect and inter-regional contrast evaluation indicators compared to the relevant methods ,such as the two-dimensional maximum Shannon entropy method , the two-dimensional Shannon cross entropy method,the two-dimensional Tsallis entropy method, and the two-dimensional symmetrical Tsallis cross entropy method .It can segment objects more accurately and has a faster running speed .%交叉熵能够度量图像分割前后的差异,与Shannon交叉熵相比,引入参数q的Tsallis交叉熵则为图像阈值分割提供了灵活性和普适性,而非对称Tsallis交叉熵的表达形式更加简洁。由此,提出了蜂群优化的二维非对称Tsal-lis交叉熵图像阈值选取方法。首先引出了非对称Tsallis交叉熵,导出了二维非对称Tsallis交叉熵阈值选取公式,并利用递推方式计算阈值选取准则函数涉及的中间变量,建立查找表,消除冗余运算;然后采用蜂群算法搜寻最

  10. Two-dimensional and three-dimensional dynamic imaging of live biofilms in a microchannel by time-of-flight secondary ion mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Xin; Marshall, Matthew J.; Xiong, Yijia; Ma, Xiang; Zhou, Yufan; Tucker, Abigail E.; Zhu, Zihua; Liu, Songqin; Yu, Xiao-Ying

    2015-05-01

    A vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface) was employed for in situ chemical imaging of live biofilms using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling by sputtering materials in sequential layers resulted in live biofilm spatial chemical mapping. 2D images were reconstructed to report the first 3D images of hydrated biofilm elucidating spatial and chemical heterogeneity. 2D image principal component analysis (PCA) was conducted among biofilms at different locations in the microchannel. Our approach directly visualized spatial and chemical heterogeneity within the living biofilm by dynamic liquid ToF-SIMS.

  11. Two-dimensional imaging of molecular hydrogen in H2-air diffusion flames using two-photon laser-induced fluorescence

    Science.gov (United States)

    Lempert, W.; Kumar, V.; Glesk, I.; Miles, R.; Diskin, G.

    1991-01-01

    The use of a tunable ArF laser at 193.26 nm to record simultaneous single-laser-shot, planar images of molecular hydrogen and hot oxygen in a turbulent H2-air diffusion flame. Excitation spectra of fuel and oxidant-rich flame zones confirm a partial overlap of the two-photon H2 and single-photon O2 Schumann-Runge absorption bands. UV Rayleigh scattering images of flame structure and estimated detection limits for the H2 two-photon imaging are also presented.

  12. Two-dimensional quantum repeaters

    Science.gov (United States)

    Wallnöfer, J.; Zwerger, M.; Muschik, C.; Sangouard, N.; Dür, W.

    2016-11-01

    The endeavor to develop quantum networks gave rise to a rapidly developing field with far-reaching applications such as secure communication and the realization of distributed computing tasks. This ultimately calls for the creation of flexible multiuser structures that allow for quantum communication between arbitrary pairs of parties in the network and facilitate also multiuser applications. To address this challenge, we propose a two-dimensional quantum repeater architecture to establish long-distance entanglement shared between multiple communication partners in the presence of channel noise and imperfect local control operations. The scheme is based on the creation of self-similar multiqubit entanglement structures at growing scale, where variants of entanglement swapping and multiparty entanglement purification are combined to create high-fidelity entangled states. We show how such networks can be implemented using trapped ions in cavities.

  13. Two-dimensional capillary origami

    Science.gov (United States)

    Brubaker, N. D.; Lega, J.

    2016-01-01

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid.

  14. Radiographic evaluation of the maxillary sinus prior to dental implant therapy: A comparison between two dimensional and three dimensional radiographic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tadinada, Aditya; Fung, Karen; Thacker, Sejal; Mahdian, Mina; Jadhaw, Aniket; Schincaglia, Gian Pietro [University of Connecticut School of Dental Medicine, Farmington (United States)

    2015-09-15

    This study was performed to evaluate the diagnostic efficacy of panoramic radiography and cone-beam computed tomography (CBCT) in detecting sinus pathology. This study was based on a retrospective evaluation of patients who had undergone both a panoramic radiograph and a CBCT exam. A total of 100 maxillary sinuses were evaluated. Four examiners with various levels of expertise evaluated the images using a five-point scoring system. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficacy of the two modalities. The image analysis was repeated twice, with at least two weeks between the evaluation sessions. Interobserver reliability was assessed using Cronbach's alpha, and intraobserver reliability was assessed using Cohen's kappa. Maxillary sinus pathology was detected in 72% of the patients. High interobserver and intraobserver reliability were observed for both imaging modalities and among the four examiners. Statistical analyses using ROC curves demonstrated that the CBCT images had a larger area under the curve (0.940) than the panoramic radiographs (0.579). Three-dimensional evaluation of the sinus with CBCT was significantly more reliable in detecting pathology than panoramic imaging.

  15. Robust gray-image face detector based on local statistical features

    Institute of Scientific and Technical Information of China (English)

    王琳; 冯正进; 崔光亮

    2004-01-01

    An efficient training framework for gray-image face detection was presented. Our system includes two stages.In the first stage, the pattern rejection theory is used for features selection. The local Haar-like wavelet features used as rejection features to reject those patterns are not faces obviously. In the second stage, the Kullback-Leibler divergence in information theory is applied to choose more effective features further and to construct hierarchical classifier. The probability functions of two classes are estimated by joint-histograms. Final decisions are made according to the likelihood ratios between two classes. The experimental results show that our system is the same robust and efficient as the best reported methods, while the training efficiency is higher than others.

  16. RESEARCH ON TWO-DIMENSIONAL LDA FOR FACE RECOGNITION

    Institute of Scientific and Technical Information of China (English)

    Han Ke; Zhu Xiuchang

    2006-01-01

    The letter presents an improved two-dimensional linear discriminant analysis method for feature extraction. Compared with the current two-dimensional methods for feature extraction, the improved two-dimensional linear discriminant analysis method makes full use of not only the row and the column direction information of face images but also the discriminant information among different classes. The method is evaluated using the Nanjing University of Science and Technology (NUST) 603 face database and the Aleix Martinez and Robert Benavente (AR) face database. Experimental results show that the method in the letter is feasible and effective.

  17. Role of two dimensional strain and strain rate imaging in assessment of left ventricular systolic function in patients with rheumatic mitral stenosis and normal ejection fraction

    Directory of Open Access Journals (Sweden)

    Hany Younan

    2015-09-01

    Conclusion: Patients with MS and preserved EF% had lower 2D longitudinal LV systolic S and Sr compared to the control group. 2D longitudinal LV systolic S and Sr imaging appears to be useful in the detection of subclinical LV systolic dysfunction in patients with MS and preserved EF%.

  18. 基于CT图像的金属块二维坐标检测算法%Two-dimensional coordinate detection algorithm based on the CT image of the piece of metal

    Institute of Scientific and Technical Information of China (English)

    廖干洲

    2013-01-01

    由于其图像扫描精度高、清晰度高等优点,CT图像已经在成为流行的医学影像工具,但传统医生对CT图像的使用仍然停留在肉眼查看图像,以寻找关键位置的方式,缺乏坐标精度。针对该问题,本文提出了用图像预处理以及区域增长的方式,自动识别CT图像关键位置的二维坐标,并用金属块作为例子,进行了多次实验,在坐标识别的精度上,结果令人满意。%Because of its high precision, high definition image scanning advantages,CT image has become popular in medical imaging tool,but the traditional doctor on CT image using still remain in the macroscopic view images,to search for the key position,lack of coordinate precision.Aiming at this problem,this paper put forward by image pretreatment and regional growth method, automatic recognition of CT key image position of two-dimensional coordinates,and using the metal block as an example,conducted a number of experiments,in coordinate accuracy of recognition,with satisfactory results.

  19. Low gray scale values of computerized images of carotid plaques associated with increased levels of triglyceride-rich lipoproteins and with increased plaque lipid content

    DEFF Research Database (Denmark)

    Grønholdt, Marie-Louise M.; Nordestgaard, Børge; Weibe, Britt M.

    1997-01-01

    Relatioin between low gray scale values in computerized images of carotid plaques and 1) plasma levels of triglyceride-rich lipoproteins and 2) plaque lipid content......Relatioin between low gray scale values in computerized images of carotid plaques and 1) plasma levels of triglyceride-rich lipoproteins and 2) plaque lipid content...

  20. Application of Image Measurement and Continuum Mechanics to the Direct Measurement of Two-Dimensional Finite Strain in a Complex Fibro-Porous Material

    Science.gov (United States)

    Britton, Paul; Loughran, Jeff

    This paper outlines a computational procedure that has been implemented for the direct measurement of finite material strains from digital images taken of a material surface during plane-strain process experiments. The selection of both hardware and software components of the image processing system is presented, and the numerical procedures developed for measuring the 2D material deformations are described. The algorithms are presented with respect to two-roll milling of sugar cane bagasse, a complex fibro-porous material that undergoes large strains during processing to extract the sucrose-rich liquid. Elaborations are made in regard to numerical developments for other forms of experimentation, algorithm calibrations and measurement improvements. Finite 2D strain results are shown for both confined uniaxial compression and two-roll milling experiments.

  1. Connected shape-size pattern spectra for rotation and scale-invariant classification of gray-scale images

    NARCIS (Netherlands)

    Urbach, Erik R.; Roerdink, Jos B.T.M.; Wilkinson, Michael H.F.

    2007-01-01

    In this paper, we describe a multiscale and multishape morphological method for pattern-based analysis and classification of gray-scale images using connected operators. Compared with existing methods, which use structuring elements, our method has three advantages. First, in our method, the time ne

  2. Classifying Two-dimensional Hyporeductive Triple Algebras

    CERN Document Server

    Issa, A Nourou

    2010-01-01

    Two-dimensional real hyporeductive triple algebras (h.t.a.) are investigated. A classification of such algebras is presented. As a consequence, a classification of two-dimensional real Lie triple algebras (i.e. generalized Lie triple systems) and two-dimensional real Bol algebras is given.

  3. 二维离散小波变换滤波在医学图像去噪的应用研究%Research on Two Dimensional Discrete Wavelet Transform Denoising in Medical Image

    Institute of Scientific and Technical Information of China (English)

    王静

    2016-01-01

    医学图像降噪必须做到既降低图像噪声又保留图像细节。通过对二维离散小波变换滤波去噪的研究以及实验表明。采用硬阈值法时,在去噪过程中如果阈值选取太小,降噪后的图像仍然有噪声,如果阈值太大,重要图像特性被滤掉,会引起偏差。因此对于不同尺度的小波系数应该选取不同的阈值进行医学图像处理。%Medical image denoising must do both to reduce image noise and retain image details. Research based on the two-dimensional discrete wavelet transform denoising filter and experiment. The hard threshold method in denoising process, if the threshold is too small, the denoised image is still noise, if the threshold is too large, an important characteristic of image is filtered out, will cause the deviation. The wavelet coefficients of different scales should select different thresholds for medical image processing.

  4. Evaluation of Right Ventricular Global Longitudinal Function in Patients with Tetralogy of Fallot by Two-dimensional Ultrasound Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    李玉曼; 谢明星; 王新房; 吕清; 卢晓芳; 杨亚利; 马红; 方凌云; 张静; 李卫芹

    2010-01-01

    Quantification of right ventricular(RV)volume and function remains a challenge because of RV complex geometry by conventional echocardiography.The purpose of this study was to assess RV global longitudinal function in patients with tetralogy of Fallot(TOF)by 2-dimensional ultrasound speckle tracking imaging(STI).Thirty-eight patients with TOF were enrolled in this study and divided into child group(n=25)and adult group(n=13)according to age.Thirty-eight age-and sex-matched normal subjects were selected as c...

  5. Development of a Semi-Automatic Technique for Flow Estimation using Optical Flow Registration and k-means Clustering on Two Dimensional Cardiovascular Magnetic Resonance Flow Images

    DEFF Research Database (Denmark)

    Brix, Lau; Christoffersen, Christian P. V.; Kristiansen, Martin Søndergaard

    of the aorta. Methods: 2D phase contrast flow images of the aorta were acquired from a patient with an enlarged pulmonary artery on a Philips Achieva 1.5T CMR system. The cardiac motion was removed from the data set using the Cornelius/Kanade registration algorithm. The time resolved flow data...... promising because it saves time for post-processing. However, the k-means cluster approach is not comprehensive for quantitative flow estimations as it is but seems feasible for a subsequent segmentation algorithm like deformable contours (i.e. snakes). Future work may overcome this manual part and make...

  6. A Multichannel Gray Level Co-Occurrence Matrix for Multi/Hyperspectral Image Texture Representation

    Directory of Open Access Journals (Sweden)

    Xin Huang

    2014-09-01

    Full Text Available This study proposes a novel method for multichannel image gray level co-occurrence matrix (GLCM texture representation. It is well known that the standard procedure for the automatic extraction of GLCM textures is based on a mono-spectral image. In real applications, however, the GLCM texture feature extraction always refers to multi/hyperspectral images. The widely used strategy to deal with this issue is to calculate the GLCM from the first principal component or the panchromatic band, which do not include all the useful information. Accordingly, in this study, we propose to represent the multichannel textures for multi/hyperspectral imagery by the use of: (1 clustering algorithms; and (2 sparse representation, respectively. In this way, the multi/hyperspectral images can be described using a series of quantized codes or dictionaries, which are more suitable for multichannel texture representation than the traditional methods. Specifically, K-means and fuzzy c-means methods are adopted to generate the codes of an image from the clustering point of view, while a sparse dictionary learning method based on two coding rules is proposed to produce the texture primitives. The proposed multichannel GLCM textural extraction methods were evaluated with four multi/hyperspectral datasets: GeoEye-1 and QuickBird multispectral images of the city of Wuhan, the well-known AVIRIS hyperspectral dataset from the Indian Pines test site, and the HYDICE airborne hyperspectral dataset from the Washington DC Mall. The results show that both the clustering-based and sparsity-based GLCM textures outperform the traditional method (extraction based on the first principal component in terms of classification accuracies in all the experiments.

  7. Crack detection in magnetic tile images using nonsubsampled shearlet transform and envelope gray level gradient

    Science.gov (United States)

    Yang, Chengli; Liu, Peiyong; Yin, Guofu; Wang, Ling

    2017-05-01

    A novel algorithm based on nonsubsampled shearlet transform (NSST) and envelope gray level gradient (EGLG) is proposed for detecting low-contrast cracks in variably illuminated magnetic tile images. The algorithm first adopted NSST to decompose the original images into multiple subbands at different directions and scales. Then a novel column filtering based on EGLG was employed to remove the uneven background in the approximation subband, and a shearlet coefficient variance discriminator (SCVD) was used to eliminate interferences of noise and textures in the detail subbands. Finally the cracks were extracted from the reconstructed images. To verify the validity of the proposed algorithm, extensive experiments were conducted in a novel machine vision based system and its comparison with traditional algorithms was given. Experimental results show that this method achieves an accuracy rate of 95.5% in detecting cracks longer than 0.9 mm with an average runtime of 0.576 s, and outperforms traditional methods in terms of accuracy and robustness.

  8. Differentiation of hypertrophic cardiomyopathy and cardiac amyloidosis from other causes of ventricular wall thickening by two-dimensional strain imaging echocardiography.

    Science.gov (United States)

    Sun, Jing Ping; Stewart, William J; Yang, Xing Sheng; Donnell, Robert O; Leon, Angel R; Felner, Joel M; Thomas, James D; Merlino, John D

    2009-02-01

    Hypertension is the most common cause of left ventricular (LV) hypertrophy. However, multiple causes can lead to LV hypertrophy, each of which has different histological and mechanical properties. To assess the value of a novel speckle-tracking echocardiographic measurement of myocardial strain and strain rate in defining the mechanical properties of LV hypertrophy, 20 patients with asymmetric hypertrophic cardiomyopathy, 24 patients with secondary LV hypertrophy, 12 patients with biopsy-proved confirmed cardiac amyloidosis, and 22 age-matched healthy asymptomatic volunteers were studied. Patients with amyloidosis had severe diastolic dysfunction, and myocardial deformation was significantly decreased. The new technique allowed cardiac amyloid to be easily differentiated from the other categories. In patients with hypertrophic cardiomyopathy, there was segmental myocardium dysfunction as assessed by strain imaging. LV global systolic velocity and radial displacement were higher, and abnormal relaxation was more frequent, in the group with secondary LV hypertrophy than in normal controls. In conclusion, the observations from strain parameters derived from speckle tracking were consistent with the known underlying pathology of each condition, which speaks to the value of strain imaging. Cardiac amyloid profoundly alters all strain parameters, and analysis of these parameters could aid in the diagnosis.

  9. Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 II. Two-dimensional Magnetic Doppler Imaging in all four Stokes parameters

    CERN Document Server

    Rusomarov, N; Ryabchikova, T; Piskunov, N

    2014-01-01

    Aims: We present a magnetic Doppler imaging study from all Stokes parameters of the cool, chemically peculiar star HD 24712. This is the very first such analysis performed at a resolving power exceeding 10^5. Methods: The analysis is performed on the basis of phase-resolved observations of line profiles in all four Stokes parameters obtained with the HARPSpol instrument attached at the 3.6-m ESO telescope. We use the magnetic Doppler imaging code, INVERS10, which allows us to derive the magnetic field geometry and surface chemical abundance distributions simultaneously. Results: We report magnetic maps of HD 24712 recovered from a selection of FeI, FeII, NdIII, and NaI lines with strong polarization signals in all Stokes parameters. Our magnetic maps successfully reproduce most of the details available from our observation data. We used these magnetic field maps to produce abundance distribution map of Ca. This new analysis shows that the surface magnetic field of HD 24712 has a dominant dipolar component wit...

  10. Two-dimensional permittivity and conductivity imaging by full waveform inversion of multioffset GPR data: a frequency-domain quasi-Newton approach

    Science.gov (United States)

    Lavoué, F.; Brossier, R.; Métivier, L.; Garambois, S.; Virieux, J.

    2014-04-01

    Full waveform inversion of ground-penetrating radar data is an emerging technique for the quantitative, high-resolution imaging of the near subsurface. Here, we present a 2-D frequency-domain full waveform inversion for the simultaneous reconstruction of the dielectric permittivity and of the electrical conductivity. The inverse problem is solved with a quasi-Newton optimization scheme, where the influence of the Hessian is approximated by the L-BFGS-B algorithm. This formulation can be considered to be fully multiparameter since it enables to update permittivity and conductivity values within the same descent step, provided we define scales of measurement through a reference permittivity, a reference conductivity, and an additional scaling factor. Numerical experiments on a benchmark from the literature demonstrate that the inversion is very sensitive to the parameter scaling, despite the consideration of the approximated Hessian that should correct for parameter dimensionalities. A proper scaling should respect the natural sensitivity of the misfit function and give priority to the parameter that has the most impact on the data (the permittivity, in our case). We also investigate the behaviour of the inversion with respect to frequency sampling, considering the selected frequencies either simultaneously or sequentially. As the relative imprint of permittivity and conductivity in the data varies with frequency, the simultaneous reconstruction of both parameters takes a significant benefit from broad frequency bandwidth data, so that simultaneous or cumulative strategies should be favoured. We illustrate our scaling approach with a realistic synthetic example for the imaging of a complex subsurface from on-ground multioffset data. Considering data acquired only from the ground surface increases the ill-posedness of the inverse problem and leads to a strong indetermination of the less-constrained conductivity parameters. A Tikhonov regularization can prevent the

  11. Two-dimensional imaging of edge-localized modes in KSTAR plasmas unperturbed and perturbed by n=1 external magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Yun, G. S.; Lee, W.; Choi, M. J.; Lee, J.; Park, H. K. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Domier, C. W.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Tobias, B. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Donne, A. J. H. [FOM-Institute for Plasma Physics Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Einhoven University of Technology, 5600 MB Einhoven (Netherlands); Lee, J. H.; Jeon, Y. M.; Yoon, S. W. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Collaboration: KSTAR Team

    2012-05-15

    The temporal evolution of edge-localized modes (ELMs) has been studied using a 2-D electron cyclotron emission imaging system in the KSTAR tokamak. The ELMs are observed to evolve in three distinctive stages: the initial linear growth of multiple filamentary structures having a net poloidal rotation, the interim state of regularly spaced saturated filaments, and the final crash through a short transient phase characterized by abrupt changes in the relative amplitudes and distance among filaments. The crash phase, typically consisted of multiple bursts of a single filament, involves a complex dynamics, poloidal elongation of the bursting filament, development of a fingerlike bulge, and fast localized burst through the finger. Substantial alterations of the ELM dynamics, such as mode number, poloidal rotation, and crash time scale, have been observed under external magnetic perturbations with the toroidal mode number n= 1.

  12. Two-dimensional function photonic crystals

    CERN Document Server

    Wu, Xiang-Yao; Liu, Xiao-Jing; Liang, Yu

    2016-01-01

    In this paper, we have firstly proposed two-dimensional function photonic crystals, which the dielectric constants of medium columns are the functions of space coordinates $\\vec{r}$, it is different from the two-dimensional conventional photonic crystals constituting by the medium columns of dielectric constants are constants. We find the band gaps of two-dimensional function photonic crystals are different from the two-dimensional conventional photonic crystals, and when the functions form of dielectric constants are different, the band gaps structure should be changed, which can be designed into the appropriate band gaps structures by the two-dimensional function photonic crystals.

  13. A study of the electron image due to ionizing events in a two-dimensional liquid argon TPC with a 24 cm drift gap

    Science.gov (United States)

    Bonetti, S.; Braggiotti, A.; Buckley, E.; Campanella, M.; Carugno, G.; Cecchet, G.; Cennini, P.; Centro, S.; Ciocio, A.; Cittolin, S.; Dainese, B.; Ferro-Luzzi, M.; Gasparini, F.; Gonidec, A.; Manfredi, P. F.; Meroni, E.; Muñoz, R.; Perreau, J.-M.; Pietropaolo, F.; Ptohos, F.; Ragusa, F.; Rossi, P.; Rubbia, C.; Schinzel, D.; Schmidt, W. F.; Seidl, W.

    1990-01-01

    We have tested a liquid argon time projection chamber with a novel wire configuration based on electrostatic focussing which allows the realization of a nondestructive detection of the electron image produced by ionizing events. The chamber was tested in a 5 GeV pion beam at the CERN proton synchrotron. The measured pulse shapes at both 200 V/cm and 500 V/cm were in very good agreement with the expected shapes, calculated taking into account the electron lifetime, the response of the electronics and the longitudinal diffusion of the electron cloud. The measured electron drift velocity was in good agreement with the results of other workers as well as with our previous measurements. We have also analysed a sample of events containing delta rays in order to study the behaviour of low-energy electrons in the liquid argon. We find that for electron energies greater than 5 MeV the measured energy spectrum agrees very well with the predicted spectrum after corrections for acceptance and energy loss, hence demonstrating the feasibility of recognizing low-energy electrons in liquid argon.

  14. Two-dimensional spectroscopic imaging with combined free induction decay and long-TE acquisition (FID echo spectroscopic imaging, FIDESI) for the detection of intramyocellular lipids in calf muscle at 7 T.

    Science.gov (United States)

    Just Kukurova, Ivica; Valkovič, Ladislav; Bogner, Wolfgang; Gajdošík, Martin; Krššák, Martin; Gruber, Stephan; Trattnig, Siegfried; Chmelík, Marek

    2014-08-01

    The aim of this study was to introduce a two-dimensional chemical shift imaging (2D CSI) sequence, with simultaneous acquisition of free induction decay (FID) and long TEs, for the detection and quantification of intramyocellular lipids (IMCLs) in the calf at 7 T. The feasibility of the new 2D CSI sequence, which acquires FID (acquisition delay, 1.3 ms) and an echo (long TE) in one measurement, was evaluated in phantoms and volunteers (n = 5): TR/TE*/TE = 800/1.3/156 ms; 48 × 48 matrix; field of view, 200 × 200 × 20 mm(3) ; Hamming filter; no water suppression; measurement time, 22 min 2 s. The IMCL concentration and subcutaneous lipid contamination were assessed. Spectra in the tibialis anterior (TA), gastrocnemius (GM) and soleus (SOL) muscles were analyzed. The water signal from the FID acquisition was used as an internal concentration reference. In the spectra from subcutaneous adipose tissue (SUB) and bone marrow (BM), an unsaturation index (UI) of the vinyl-H (5.3 ppm) to methyl-CH3 ratio, and a polyunsaturation index (pUI) of the diallylic-H (2.77 ppm) to -CH3 ratio, were calculated. Long-TE spectra from muscles showed a simplified spectral pattern with well-separated IMCL for several muscle groups in the same scan. The IMCL to water ratio was largest in SOL (0.66% ± 0.23%), and lower in GM (0.37% ± 0.14%) and TA (0.36% ± 0.12%). UI and pUI for SUB were 0.65 ± 0.06 and 0.18 ± 0.04, respectively, and for BM were 0.60 ± 0.16 and 0.18 ± 0.08, respectively. The new sequence, with the proposed name 'free induction decay echo spectroscopic imaging' (FIDESI), provides information on both specific lipid resonances and water signal from different tissues in the calf, with high spectral and spatial resolution, as well as minimal voxel bleeding and subcutaneous lipid contamination, in clinically acceptable measurement times.

  15. Hadamard States and Two-dimensional Gravity

    CERN Document Server

    Salehi, H

    2001-01-01

    We have used a two-dimensional analog of the Hadamard state-condition to study the local constraints on the two-point function of a linear quantum field conformally coupled to a two-dimensional gravitational background. We develop a dynamical model in which the determination of the state of the quantum field is essentially related to the determination of a conformal frame. A particular conformal frame is then introduced in which a two-dimensional gravitational equation is established.

  16. Topological defects in two-dimensional crystals

    OpenAIRE

    Chen, Yong; Qi, Wei-Kai

    2008-01-01

    By using topological current theory, we study the inner topological structure of the topological defects in two-dimensional (2D) crystal. We find that there are two elementary point defects topological current in two-dimensional crystal, one for dislocations and the other for disclinations. The topological quantization and evolution of topological defects in two-dimensional crystals are discussed. Finally, We compare our theory with Brownian-dynamics simulations in 2D Yukawa systems.

  17. Technique for gray-scale visual light and infrared image fusion based on non-subsampled shearlet transform

    Science.gov (United States)

    Kong, Weiwei

    2014-03-01

    A novel image fusion technique based on NSST (non-subsampled shearlet transform) is presented, aiming at resolving the fusion problem of spatially gray-scale visual light and infrared images. NSST, as a new member of MGA (multi-scale geometric analysis) tools, possesses not only flexible direction features and optimal shift-invariance, but much better fusion performance and lower computational costs compared with several current popular MGA tools such as NSCT (non-subsampled contourlet transform). We specifically propose new rules for the fusion of low and high frequency sub-band coefficients of source images in the second step of the NSST-based image fusion algorithm. First, the source images are decomposed into different scales and directions using NSST. Then, the model of region average energy (RAE) is proposed and adopted to fuse the low frequency sub-band coefficients of the gray-scale visual light and infrared images. Third, the model of local directional contrast (LDC) is given and utilized to fuse the corresponding high frequency sub-band coefficients. Finally, the final fused image is obtained by using inverse NSST to all fused sub-images. In order to verify the effectiveness of the proposed technique, several current popular ones are compared over three different publicly available image sets using four evaluation metrics, and the experimental results demonstrate that the proposed technique performs better in both subjective and objective qualities.

  18. Two-dimensional signal analysis

    CERN Document Server

    Garello, René

    2010-01-01

    This title sets out to show that 2-D signal analysis has its own role to play alongside signal processing and image processing.Concentrating its coverage on those 2-D signals coming from physical sensors (such as radars and sonars), the discussion explores a 2-D spectral approach but develops the modeling of 2-D signals and proposes several data-oriented analysis techniques for dealing with them. Coverage is also given to potential future developments in this area.

  19. Strongly interacting two-dimensional Dirac fermions

    NARCIS (Netherlands)

    Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.

    2009-01-01

    We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature

  20. Topology optimization of two-dimensional waveguides

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2003-01-01

    In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss.......In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss....

  1. Contrast Enhancement Method Based on Gray and Its Distance Double-Weighting Histogram Equalization for 3D CT Images of PCBs

    Directory of Open Access Journals (Sweden)

    Lei Zeng

    2016-01-01

    Full Text Available Cone beam computed tomography (CBCT is a new detection method for 3D nondestructive testing of printed circuit boards (PCBs. However, the obtained 3D image of PCBs exhibits low contrast because of several factors, such as the occurrence of metal artifacts and beam hardening, during the process of CBCT imaging. Histogram equalization (HE algorithms cannot effectively extend the gray difference between a substrate and a metal in 3D CT images of PCBs, and the reinforcing effects are insignificant. To address this shortcoming, this study proposes an image enhancement algorithm based on gray and its distance double-weighting HE. Considering the characteristics of 3D CT images of PCBs, the proposed algorithm uses gray and its distance double-weighting strategy to change the form of the original image histogram distribution, suppresses the grayscale of a nonmetallic substrate, and expands the grayscale of wires and other metals. The proposed algorithm also enhances the gray difference between a substrate and a metal and highlights metallic materials. The proposed algorithm can enhance the gray value of wires and other metals in 3D CT images of PCBs. It applies enhancement strategies of changing gray and its distance double-weighting mechanism to adapt to this particular purpose. The flexibility and advantages of the proposed algorithm are confirmed by analyses and experimental results.

  2. Imaging the functional connectivity of the Periaqueductal Gray during genuine and sham electroacupuncture treatment

    Directory of Open Access Journals (Sweden)

    Tu Peichi

    2010-11-01

    Full Text Available Abstract Background Electroacupuncture (EA is currently one of the most popular acupuncture modalities. However, the continuous stimulation characteristic of EA treatment presents challenges to the use of conventional functional Magnetic Resonance Imaging (fMRI approaches for the investigation of neural mechanisms mediating treatment response because of the requirement for brief and intermittent stimuli in event related or block designed task paradigms. A relatively new analysis method, functional connectivity fMRI (fcMRI, has great potential for studying continuous treatment modalities such as EA. In a previous study, we found that, compared with sham acupuncture, EA can significantly reduce Periaqueductal Gray (PAG activity when subsequently evoked by experimental pain. Given the PAG's important role in mediating acupuncture analgesia, in this study we investigated functional connectivity with the area of the PAG we previously identified and how that connectivity was affected by genuine and sham EA. Results Forty-eight subjects, who were randomly assigned to receive either genuine or sham EA paired with either a high or low expectancy manipulation, completed the study. Direct comparison of each treatment mode's functional connectivity revealed: significantly greater connectivity between the PAG, left posterior cingulate cortex (PCC, and precuneus for the contrast of genuine minus sham; significantly greater connectivity between the PAG and right anterior insula for the contrast of sham minus genuine; no significant differences in connectivity between different contrasts of the two expectancy levels. Conclusions Our findings indicate the intrinsic functional connectivity changes among key brain regions in the pain matrix and default mode network during genuine EA compared with sham EA. We speculate that continuous genuine EA stimulation can modify the coupling of spontaneous activity in brain regions that play a role in modulating pain

  3. SU-E-I-15: Quantitative Evaluation of Dose Distributions From Axial, Helical and Cone-Beam CT Imaging by Measurement Using a Two-Dimensional Diode-Array Detector

    Energy Technology Data Exchange (ETDEWEB)

    Chacko, M; Aldoohan, S; Sonnad, J; Ahmad, S; Ali, I [University of Oklahoma Health Science Center, Oklahoma City, OK (United States)

    2015-06-15

    Purpose: To evaluate quantitatively dose distributions from helical, axial and cone-beam CT clinical imaging techniques by measurement using a two-dimensional (2D) diode-array detector. Methods: 2D-dose distributions from selected clinical protocols used for axial, helical and cone-beam CT imaging were measured using a diode-array detector (MapCheck2). The MapCheck2 is composed from solid state diode detectors that are arranged in horizontal and vertical lines with a spacing of 10 mm. A GE-Light-Speed CT-simulator was used to acquire axial and helical CT images and a kV on-board-imager integrated with a Varian TrueBeam-STx machine was used to acquire cone-beam CT (CBCT) images. Results: The dose distributions from axial, helical and cone-beam CT were non-uniform over the region-of-interest with strong spatial and angular dependence. In axial CT, a large dose gradient was measured that decreased from lateral sides to the middle of the phantom due to large superficial dose at the side of the phantom in comparison with larger beam attenuation at the center. The dose decreased at the superior and inferior regions in comparison to the center of the phantom in axial CT. An asymmetry was found between the right-left or superior-inferior sides of the phantom which possibly to angular dependence in the dose distributions. The dose level and distribution varied from one imaging technique into another. For the pelvis technique, axial CT deposited a mean dose of 3.67 cGy, helical CT deposited a mean dose of 1.59 cGy, and CBCT deposited a mean dose of 1.62 cGy. Conclusions: MapCheck2 provides a robust tool to measure directly 2D-dose distributions for CT imaging with high spatial resolution detectors in comparison with ionization chamber that provides a single point measurement or an average dose to the phantom. The dose distributions measured with MapCheck2 consider medium heterogeneity and can represent specific patient dose.

  4. Analysis of Two-Dimensional Gel Electrophoresis Images of Protein from Posterior Silk Gland of Silkworm (Bombyx mori) on Day 1 and Day 4 in the 5th Instar Stage

    Institute of Scientific and Technical Information of China (English)

    WU Wei-cheng; ZHONG Bo-xiong; GAO Qi-kang; CHEN Jin-e; YE Jian; QIAN Yang-wen; LI Jian-ying; LU Hua-yun; MENG Zhi-qi; NI Chun-xiao

    2007-01-01

    The posterior silk gland (PSG) of silkworm is an important organ where fibroin is synthesized and secreted exclusively.Because fibroin constitutes 75-80% of the silk filament, the mechanism governing fibroin secretion, quality and yield of cocoon can be elucidated by the study on the PSG. Using two-dimensional gel electrophoresis (2-DE) and image analysis system, the changes in the protein composition in the PSG cell were investigated on the day 1 (D1) and day 4 (D4) in the 5th instar stage from five different strains of silkworm (Bombyx mori). While differences at protein level between days and strains were far less than those observed at the gene level using EST analysis. The change trends in protein composition from D1 to D4 were diverse among the different strains. The results suggest that the secretion of fibroin is regulated by multiple proteins. The site of regulation and the proteins responsible for the regulation vary with the strain, which leads to differences between strains in the capacity of fibroin secretion in the PSG cell.

  5. IMMUNOHISTOCHEMICAL IMAGE SEGMENTATION USING IMPROVED TWO-DIMENSIONAL OTSU AND COMBINING HSV SPACE%结合 HSV 空间的改进二维 Otsu 免疫组化图像分割

    Institute of Scientific and Technical Information of China (English)

    兰红; 胡涵

    2016-01-01

    肝脏免疫组化图像中阳性区域的定量分析对肝癌的早期诊断有非常重要的意义。针对真彩色免疫组化图像特征,结合HSV 空间对二维 Otsu 算法进行改进。首先针对二维 Otsu 算法每次计算类间测度矩阵的迹需要遍历整幅图像导致运算量大耗时多的不足,提出一种快速递推算法,利用快速 Otsu 算法对图像进行预分割;然后针对分割结果中目标区域包含的少量阴性区域,结合图像的 HSV 空间特征进行优化。将预分割结果与 H 分量作交集运算,将交集运算结果与预分割结果作差集运算,得到初分割结果;将初分割结果与 H 分量和 S 分量的交集运算结果做并集运算,得到最终分割结果。通过与 Otsu 的对比实验表明,改进算法更好地实现了阳性区域的目标提取,提高了分割的精度。%The quantitative analysis of the positive area of liver immunohistochemical image is significant to the early diagnosis of liver cancer.Aiming at the features of true colour immunohistochemical image,we improved the two-dimensional Otsu algorithm in combination with HSV space.First,in view of the disadvantage that the two-dimensional Otsu has to traverse entire image when ever to calculate the trace of inter-class measure matrix and in turn leads to heavy computation and large time consumption,we proposed a fast recursion algorithm, which uses the fast Otsu to do the pre-segmentation on the image.Then,aiming at the small amount of negative area contained in target area of the segmented result,we optimised it combining the HSV space feature of the image.We carried out the intersection operation on the presegmentation result and the H component,and the subtraction operation on the intersection operation result and the pre-segmentation result to get initial segmentation result,and then carried out the union operation on the initial segmentation result and the result of H and S components

  6. Phase-sensitive two-dimensional neutron shearing interferometer and Hartmann sensor

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Kevin

    2015-12-08

    A neutron imaging system detects both the phase shift and absorption of neutrons passing through an object. The neutron imaging system is based on either of two different neutron wavefront sensor techniques: 2-D shearing interferometry and Hartmann wavefront sensing. Both approaches measure an entire two-dimensional neutron complex field, including its amplitude and phase. Each measures the full-field, two-dimensional phase gradients and, concomitantly, the two-dimensional amplitude mapping, requiring only a single measurement.

  7. Clinical value of two-dimensional strain imaging in locating Ischemia myocardium%二维超声应变对心肌缺血定位的临床应用研究

    Institute of Scientific and Technical Information of China (English)

    王亚非; 于春艳; 张鲁春; 李志远; 王雁博; 王金凤; 马晓华

    2013-01-01

    Objective To evaluate regional dyssynergia of left ventricular of patients with cardiac ischemia or myocardial infraction by two-dimensional strain imaging (2DSI) and to identify the accuracy of using 2DSI to locate ischemia myocardium. Methods 36 cases with myocardial infarction (MI) and stable coronary heart disease (CHD) were respectively selected, while 36 cases of healthy group were selected as control group. LV longitudinal peak of systolic strain were obtained from the 3 groups. The strain parameter and the ischemia range that came from the "ox's eye" image with the results of cardioangiography (CAG) and electrocardiogram (ECG) were compared. Results ① the LV global longitudinal systolic peak and LPSS of stable CHD group and MI group were both less than these of the control group ( P <0. 05) ; ② LPSS of ischemia location in stable CHD group and MI group were both less than these of the control group ( P <0. 05, P < 0. 001, t =2. 597~3. 216). There was a positive correlation between visual ischemia range came from the "ox's eye" image and the result of CAG and ECG ( r=0. 661, P <0. 001, r=0. 598, P < 0.001, r =0.556, P <0. 001, r =0.556, P <0. 001). Conclusion Two-dimensional strain imaging (2DSI) can exactly reflect the wall motion abnormality of ischemia myocardium. It is exact, direct and easy for clinical application. It plays an important role in early diagnosis of CHD and MI. The location of cardiac ischemia and MI have characteristic practice and value of clinical application.%目的 探讨二维超声应变对缺血冠脉心肌分布区域定位的准确性及临床应用价值.方法 经临床确诊的冠心病及心肌梗死72例,获取其两组左室收缩期纵向峰值应变参数(LPSS)与健康正常组30例对照,对牛眼图缺血部位应变参数和范围分别与冠状动脉造影及心电图相应导联Q波、ST-T对照.结果 ①缺血组和梗死组左室各节段纵向收缩期峰值及整体LPSS均小于健康

  8. Research on Digital Watermarking Algorithm Based on Color Two-dimensional Code Image%基于彩色二维码图像的数字水印算法研究

    Institute of Scientific and Technical Information of China (English)

    吕慧中; 蓝凤华; 李宏昌

    2015-01-01

    This paper introduces the color two-dimensional code on the basis of introducing the traditional black and white two-dimensional code. The two dimensional code is changed into color to provide more watermark embedding position and higher visibility. The MATLAB simulation experiment proves the feasibility of embedding the watermark information in the two-dimensional code. Based on characteristics of color two-dimensional code, this paper studies the application of digital watermark in color two-dimensional code. By embedding watermark through through R, G, B color component translation and rotation, this paper designs a watermarking algorithm based on the color two-dimensional code, which can resist geometric attacks and improve the security and practicability of two-dimensional code.%在介绍了传统黑白二维码的基础上,对彩色二维码进行了介绍.将二维码变成彩色,提供了更多的水印嵌入位置和更高的不可见性.通过Matlab仿真实验,验证了在彩色二维码中嵌入水印信息的可行性,并结合彩色二维码的特点,对数字水印在彩色二维码中的应用进行研究,采用R、G和B三种颜色分量分别平移和旋转的方法嵌入水印,设计出了一种可抵抗几何攻击的彩色二维码水印算法,提高了二维码的安全性和实用性.

  9. Two Dimensional Plasmonic Cavities on Moire Surfaces

    Science.gov (United States)

    Balci, Sinan; Kocabas, Askin; Karabiyik, Mustafa; Kocabas, Coskun; Aydinli, Atilla

    2010-03-01

    We investigate surface plasmon polariton (SPP) cavitiy modes on two dimensional Moire surfaces in the visible spectrum. Two dimensional hexagonal Moire surface can be recorded on a photoresist layer using Interference lithography (IL). Two sequential exposures at slightly different angles in IL generate one dimensional Moire surfaces. Further sequential exposure for the same sample at slightly different angles after turning the sample 60 degrees around its own axis generates two dimensional hexagonal Moire cavity. Spectroscopic reflection measurements have shown plasmonic band gaps and cavity states at all the azimuthal angles (omnidirectional cavity and band gap formation) investigated. The plasmonic band gap edge and the cavity states energies show six fold symmetry on the two dimensional Moire surface as measured in reflection measurements.

  10. Two-dimensional function photonic crystals

    Science.gov (United States)

    Liu, Xiao-Jing; Liang, Yu; Ma, Ji; Zhang, Si-Qi; Li, Hong; Wu, Xiang-Yao; Wu, Yi-Heng

    2017-01-01

    In this paper, we have studied two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , that can become true easily by electro-optical effect and optical kerr effect. We calculated the band gap structures of TE and TM waves, and found the TE (TM) wave band gaps of function photonic crystals are wider (narrower) than the conventional photonic crystals. For the two-dimensional function photonic crystals, when the dielectric constant functions change, the band gaps numbers, width and position should be changed, and the band gap structures of two-dimensional function photonic crystals can be adjusted flexibly, the needed band gap structures can be designed by the two-dimensional function photonic crystals, and it can be of help to design optical devices.

  11. Two-Dimensional Planetary Surface Lander

    Science.gov (United States)

    Hemmati, H.; Sengupta, A.; Castillo, J.; McElrath, T.; Roberts, T.; Willis, P.

    2014-06-01

    A systems engineering study was conducted to leverage a new two-dimensional (2D) lander concept with a low per unit cost to enable scientific study at multiple locations with a single entry system as the delivery vehicle.

  12. CRYPTOGRAPHY OF A GRAY LEVEL IMAGE AND A COLOR IMAGE USING MODERN ADVANCED HILL CIPHER INCLUDING A PAIR OF INVOLUTORY MATRICES AS MULTIPLICANDS AND INVOLVING A SET OF FUNCTIONS

    Directory of Open Access Journals (Sweden)

    Ch. Samson

    2012-07-01

    Full Text Available In this investigation we have developed a procedure for the encryption of an image by applying modern advanced Hill Cipher including a pair of involutory matrices as multiplicands and a set of functions. Firstly we have obtained an encrypted image of a gray level image. Then this analysis is extended to an RGB color image. Here it is interesting to note that the encrypted image of the gray level image and the encrypted image of the color image do not have any resemblance with their corresponding original images. This fact ensures security of images in an effective manner. .

  13. Image analysis of concentration distribution in two-dimensional sandbox tracer experiment%二维砂箱溶质示踪实验的图像分析法

    Institute of Scientific and Technical Information of China (English)

    宋小源; 刘杰; 郑春苗

    2012-01-01

    Dye tracer has been widely used in sandbox experiments of solute transport.This study uses image analysis to determine the concentration of dye tracer in porous media.By establishing a quantitative relationship between the concentration and the hue value of the dye tracer,the concentration distribution of the dye tracer can be quickly obtained.The image analysis provides a cost-effective and high-resolution method to quantify the solute concentration distribution in two-dimensional sandbox experiment for groundwater solute transport studies.Because the range of image hue values is limited,the image analysis method can only be applied to a certain range of solute concentration.%有色示踪剂在砂箱溶质运移实验中有着广泛的应用,因此,本文介绍了一种通过对数字图像进行分析以确定多孔介质中有色示踪剂浓度分布的方法.在实验过程中,通过建立有色示踪剂浓度与图像颜色要素之间的定量关系,从而能够利用数字图像迅速确定某一时刻砂箱内部的示踪剂浓度分布.结果发现,与传统定点采样方法相比,图像分析法可以达到更高的空间和时间分辨率,从而观察到有可能被忽视的重要溶质运移过程,能够为地下水溶质运移实验研究提供了一种经济实用和高空间分辨率的数据采集手段.但由于色彩空间变化范围的限制,图像分析法只能在一定溶质浓度范围内适用.

  14. Two-dimensional ultrasound and ultrasound elastography imaging of trigger points in women with myofascial pain syndrome treated by acupuncture and electroacupuncture: a double-blinded randomized controlled pilot study.

    Science.gov (United States)

    Müller, Cristina Emöke Erika; Aranha, Maria Fernanda Montans; Gavião, Maria Beatriz Duarte

    2015-04-01

    Chronic pain has been often associated with myofascial pain syndrome (MPS), which is determined by myofascial trigger points (MTrP). New features have been tested for MTrP diagnosis. The aim of this study was to evaluate two-dimensional ultrasonography (2D US) and ultrasound elastography (UE) images and elastograms of upper trapezius MTrP during electroacupuncture (EA) and acupuncture (AC) treatment. 24 women participated, aged between 20 and 40 years (M ± SD = 27.33 ± 5.05) with a body mass index ranging from 18.03 to 27.59 kg/m2 (22.59 ± 3.11), a regular menstrual cycle, at least one active MTrP at both right (RTPz) and left trapezius (LTPz) and local or referred pain for up to six months. Subjects were randomized into EA and AC treatment groups and the control sham AC (SHAM) group. Intensity of pain was assessed by visual analogue scale; MTrP mean area and strain ratio (SR) by 2D US and UE. A significant decrease of intensity in general, RTPz, and LTPz pain was observed in the EA group (p = 0.027; p < 0.001; p = 0.005, respectively) and in general pain in the AC group (p < 0.001). Decreased MTrP area in RTPz and LTPz were observed in AC (p < 0.001) and EA groups (RTPz, p = 0.003; LTPz, p = 0.005). Post-treatment SR in RTPz and LTPz was lower than pre-treatment in both treatment groups. 2D US and UE effectively characterized MTrP and surrounding tissue, pointing to the possibility of objective confirmation of subjective EA and AC treatment effects. © The Author(s) 2014.

  15. SD LMS L-Filters for Filtration of Gray Level Images in Timespatial Domain Based on GLCM Features

    Directory of Open Access Journals (Sweden)

    Robert Hudec

    2008-01-01

    Full Text Available In this paper, the new kind of adaptive signal-dependent LMS L-filter for suppression of a mixed noise in greyscale images is developed. It is based on the texture parameter measurement as modification of spatial impulse detector structure. Moreover, the one of GLCM (Gray Level Co-occurrence Matrix features, namely, the contrast or inertia adjusted by threshold as switch between partial filters is utilised. Finally, at the positions of partial filters the adaptive LMS versions of L-filters are chosen.

  16. Assessment of speckle-pattern quality in digital image correlation based on gray intensity and speckle morphology

    Science.gov (United States)

    Park, Jihyuk; Yoon, Sungsik; Kwon, Tae-Hyun; Park, Kyoungsoo

    2017-04-01

    In digital image correlation (DIC), speckle patterns are generated on the surface of a specimen to resolve uniqueness issues. Thus, speckle patterns significantly affect the accuracy of image correlation. To assess the quality of speckle patterns, the standard deviation of gray intensities within each speckle (SDGIS) is introduced as a new metric. On the basis of the cumulative distribution of SDGIS, speckle-pattern quality measurement (ρ) is proposed, which integrates the features of gray intensity and speckle morphology. Twelve speckle patterns are generated by changing the spraying time and nozzle sizes of an airbrush because these are associated with the speckle volume fraction and speckle size, respectively. In addition, three displacement fields are used to investigate the effects of speckle patterns on the accuracy of the DIC results. For the 12 speckle images associated with the three displacement fields, the correlation results demonstrate that the proposed speckle-pattern quality measurement is inversely proportional to the averaged error of the subset method. This is statistically confirmed by evaluating the correlation coefficient and p-value. Furthermore, the error of the subset method is more affected by speckle patterns than the subset size when the subset size is sufficiently large.

  17. Gray level co-occurrence and random forest algorithm-based gender determination with maxillary tooth plaster images.

    Science.gov (United States)

    Akkoç, Betül; Arslan, Ahmet; Kök, Hatice

    2016-06-01

    Gender is one of the intrinsic properties of identity, with performance enhancement reducing the cluster when a search is performed. Teeth have durable and resistant structure, and as such are important sources of identification in disasters (accident, fire, etc.). In this study, gender determination is accomplished by maxillary tooth plaster models of 40 people (20 males and 20 females). The images of tooth plaster models are taken with a lighting mechanism set-up. A gray level co-occurrence matrix of the image with segmentation is formed and classified via a Random Forest (RF) algorithm by extracting pertinent features of the matrix. Automatic gender determination has a 90% success rate, with an applicable system to determine gender from maxillary tooth plaster images. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. On the distribution tests of the two-dimensional wavelet transform coefficients for image%图像二维小波变换系数分布的实验研究

    Institute of Scientific and Technical Information of China (English)

    张奇志

    2001-01-01

    Wavelet transform image coding scheme is the widest used one ofimage compression approaches. The quantization of wavelet transform coefficients is a key to obtain the compression image with low bit ratios and the reconstruction image with high signal to noise ratio. To obtain the optimal quantizer,the distributions of wavelet transform coefficients for image must be determined. The purpose of the experiment is to determine the distributions of wavelet transform coefficients for image. Four standard images, named “Face”, “Girl”, “Lena” and “Panda”, are selected to study the distribution rule. The “KS” statistical tests are applied to studying the distributions of wavelet transform coefficients for images. Utilizing the Vetterli biorthogonal wavelet (L=18), the images that have size of 256×256 pels with 256 gray levels are decomposed to three level and ten subimages. The results of tests of Rayleigh assumption, Laplacian assumption and Gaussian assumption are given. The results of tests have shown that the low-pass subimages are best approximated by a Gaussian distribution and the others are best approximated by a Laplacian distribution. A simulation indicates that the Laplacian assumption of coefficients yields a higher actual output signal-to-noise ratio than the Gaussian assumption.%小波变换编码是目前研究较多的图像压缩方法,变换系数的量化是获得低比特率、高信噪比压缩图像的关键步骤。为了设计最优量化器,必须确定变换系数的分布规律。选择“Face”、“Girl”、“Lena”和“Panda”4幅标准图像数据进行统计研究,用长度L=18的Vetterli双正交小波将256灰度级256×256图像分解为3层10个子带,使用“KS”测试统计方法确定图像小波变换系数的分布规律。给出了瑞利分布、高斯分布和拉普拉斯分布假设下的“KS”测试统计结果。统计结果表明,低频部分符合高斯分布,其余部分符合拉普

  19. 肥厚型心肌病右室功能的二维应变成像研究%The evaluation of right ventricular function of hypertrophic cardiomyopathy using two dimensional strain imaging

    Institute of Scientific and Technical Information of China (English)

    权欣; 李慧; 郭继鸿; 朱天刚; 江勇; 朱振辉; 王浩

    2016-01-01

    Objective To assess RV myocardial function in patients with hypertension (H-LVH) using two dimensional strain imaging prospectively. Methods One hundred and thirty-six individuals were enrolled into this study ,divided into 3 groups :hypertrophic cardiomyopathy (n= 53) , hypertrophy secondary to hypertension (n = 36 ) and normal controls (n = 47 ). Echocardiographic parameters were measured ,including right ventricular basal dimension tracing from 4-chamber view , fractional area change (FAC) ,tricuspid annular plane systolic excursion (TAPSE) ,wall thickness of interventricular septum (IVST ) and left ventricular posterior wall (PWT ) ,left ventricular end-diastolic diameter (LVIDd) ,left ventricular ejection fraction (LVEF) ,right ventricle regional and global longitudinal strain derived from two-dimensional strain imaging were compared between groups. Results The wall thickness of HCM group was significantly higher than H-LVH group and control group ,whereas LVIDd was smaller ( P 0.05). Right ventricular diameters were smaller in HCM groups than H-LVH and control groups (all P< 0.05).Significance difference of regional and global strain existed between HCM group and the other 2 groups (P< 0.01).Cut-off value of global strain was - 9.75%to diagnose right ventricular functional remodeling in HCM ( P = 0.027 ). Conclusions Two-dimensional strain is superior to traditional echo parameters. Right ventricular remodeling is prone to present in hypertrophic cardiomyopathy than hypertensive hypertrophy.%目的:应用二维应变成像定量评价肥厚型心肌病(HCM )患者的右室局部及整体应变,与高血压性左室肥厚(H-LVH)及健康人进行对比研究。方法前瞻性纳入2015年5月至2016年4月的136例患者,分为3组:HCM 53例,H-LVH 36例,正常对照47例。测量检测右心功能指标,包括右室基底段横径、右室面积变化率、三尖瓣环收缩期位移、三尖瓣环组织收缩峰值速度、右室局

  20. 使用双远心镜头的高精度二维数字图像相关测量系统%High-Accuracy Two-Dimensional Digital Image Correlation Measurement System Using a Bilateral Telecentric Lens

    Institute of Scientific and Technical Information of China (English)

    潘兵; 俞立平; 吴大方

    2013-01-01

    By comparing the two images recorded in different configurations on the same object surface, two-dimensional digital image correlation (2D-DIC) method produces full-field displacement with sub-pixel accuracy and full-field strains in the recorded images. In a practical measurement, however, various deteriorative factors, such as small out-of-plane motion of the test object surface, small out-of-plane motion of the sensor target and geometric distortion of the imaging lens may seriously impair the originally assumed linear correspondence between images displacement and object motions. In certain cases, these disadvantages may lead to significant errors in measuring displacements and strains. The measurement errors of 2D-DIC due to the above three unavoidable deteriorative factors are first described briefly. Then, the performances of three typical imaging lenses, including a standard lens, an object-side telecentric lens and a bilateral telecentric lens, against these three deteriorative factors are investigated experimentally using easy-to-implement static, out-of-plane and in-plane rigid body translation tests. A detailed examination reveals that a high-quality bilateral telecentric lens is not only insensitive to out-of-plane motions of the test object and the self-heating of a camera being used, but also demonstrates negligible lens distortion. So the bilateral lens is highly recommended for high accuracy 2D-DIC measurement.%通过比较变形前后同一平面物体表面的两幅数字图像,二维数字图像相关方法可获得亚像素精度的像面位移(以像素为单位)和应变.但在实际测量中,变形物体表面的离面位移、相机传感器平面位置的微小改变以及镜头的成像畸变,都会使原先假设的物、像面位移间的线性对应关系不再严格成立,在某些情况下会引起不能忽略的测量误差.详细分析了被测物体的离面位移、相机自热和镜头畸变对二维数字图像相关方法位

  1. TWO-DIMENSIONAL TOPOLOGY OF COSMOLOGICAL REIONIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yougang; Xu, Yidong; Chen, Xuelei [Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 China (China); Park, Changbom [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); Kim, Juhan, E-mail: wangyg@bao.ac.cn, E-mail: cbp@kias.re.kr [Center for Advanced Computation, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)

    2015-11-20

    We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two-dimensional genus curve for the early, middle, and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometre Array.

  2. Two dimensional topology of cosmological reionization

    CERN Document Server

    Wang, Yougang; Xu, Yidong; Chen, Xuelei; Kim, Juhan

    2015-01-01

    We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two dimensional genus curve for the early, middle and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometer Array.

  3. Two-Dimensional Chirp-Z Transform Imaging Algorithm for General Airborne Bistatic High Squint SAR Data Focusing%一般构型机载双站大斜视SAR二维Chirp-Z变换成像算法

    Institute of Scientific and Technical Information of China (English)

    冉金和; 李修和

    2014-01-01

    A two-dimensional Chirp-Z Transform (CZT) imaging algorithm for general bistatic high squint SAR is proposed. To deal with the serious range-azimuth cross coupling of echo signal in bistatic high squint SAR, Linear Range Walk Correction (LRWC) is performed in range frequency-azimuth time domain to correct the large LRW induced by the high squint model of platforms, and then the expression of a modified bistatic point target reference spectrum is derived. Reference Function Multiplication (RFM) is firstly performed to finish the bulk focusing. With the track decoupling formulas, phase terms of spectrum are decomposed into two independent phase terms as range-variant phase terms and azimuth-variant phase terms, and their space variances are eliminated by CZT respectively to get the focusing result. The simulation tests validate the effectiveness of the proposed imaging algorithm to focus the data of general airborne bistatic high squint SAR.%该文提出一般构型机载双站大斜视SAR的2维Chirp-Z变换(CZT)成像算法。针对双站大斜视回波信号的距离-方位向强耦合,在距离频域-方位时域校正载机大斜视引起的大距离走动,然后推导改进点目标的频谱公式。成像时,先用参考函数相乘完成回波一致聚焦,然后借助于载机轨迹解耦合公式将频谱相位分解为距离移变和方位移变的两个独立相位项,再运用CZT分别消除其空变性得到成像结果。仿真验证了该算法处理一般构型机载双站大斜视SAR回波数据的有效性。

  4. Two-dimensional x-ray diffraction

    CERN Document Server

    He, Bob B

    2009-01-01

    Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea

  5. Mobility anisotropy of two-dimensional semiconductors

    Science.gov (United States)

    Lang, Haifeng; Zhang, Shuqing; Liu, Zhirong

    2016-12-01

    The carrier mobility of anisotropic two-dimensional semiconductors under longitudinal acoustic phonon scattering was theoretically studied using deformation potential theory. Based on the Boltzmann equation with the relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was derived, showing that the influence of effective mass on mobility anisotropy is larger than those of deformation potential constant or elastic modulus. Parameters were collected for various anisotropic two-dimensional materials (black phosphorus, Hittorf's phosphorus, BC2N , MXene, TiS3, and GeCH3) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio is overestimated by the previously described method.

  6. Towards two-dimensional search engines

    OpenAIRE

    Ermann, Leonardo; Chepelianskii, Alexei D.; Shepelyansky, Dima L.

    2011-01-01

    We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Statistical properties of inf...

  7. 心肌梗死延迟增强三维与二维MR成像对比研究%Comparison study of three-dimensional and two-dimensional delayed enhancement MR imaging for myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    杨姗; 曾蒙苏; 张志勇; 金航; 马剑英; 陈财忠

    2009-01-01

    Objective To prospectively evaluate the correlation between a single breath-hold three-dimensional (3 D) and several breath-hold two-dimensional (2D) delayed enhancement MR imaging sequences in the assessment of myocardial infarction size and the differences on image quality. Methods Fifteen patients with myocardial infarction underwent MR scan by using a single breath-hold 3D inversion-recovery fast low-angle shot (FLASH) sequence and several breath-hold 2D turbo-FLASH as the reference standard. Paired-samples t test was used to compare the ratio of the infarction areas in two sequences. Two-way ANOVA was used to assess the contrast-to-noise ratio (CNR) on 3D,2D magnitude-reconstructed and 2D phase-sensitive (PS) images. P value less than 0.05 was considered to indicate a significant difference. Meanwhile subjective visual evaluation was also performed to compare the image quality. Results The infarction ratio determined by 3D MR imaging 31.28% was no significant difference with that of 2D MR imaging 30.91% and had a good correlation (t = -0.505,P =0.621,r =0.990). The CNR was significantly higher in 3D and 2D magnitude-reconstructed groups than in 2D-PS group (3D and 2D magnitude-reconstructed images, 2D P5 image, 43.43±20.67 and 34.10±14.29, 7.59±2.59, respectively) (F = 24.376, P < 0.01). However, the contrast between normal and infracted myocardium was the highest in 2D-PS group with subjective visual evaluation (scores of 3D, 2D magnitude-reconstructed and 2D-PS images, 2.33, 2.13 and 2.73, respectively). On the other hand, the background noise on 2D-PS images was the highest in 3 groups (scores of 3 D, 2 D magnitude-reconstructed and 2 D-PS images, 2.67, 2.53 and 1.20, respectively). Conclusion The myocardial infarction ratio obtained with 3D MR imaging sequence is accurate, and the image quality is good.%目的 比较屏气三维快速小角度激励序列(3D-FLASH)延迟增强扫描与多次屏气二维快速FLASH(2D-turboFLASH)延迟增强扫描的图

  8. Exact analytic flux distributions for two-dimensional solar concentrators.

    Science.gov (United States)

    Fraidenraich, Naum; Henrique de Oliveira Pedrosa Filho, Manoel; Vilela, Olga C; Gordon, Jeffrey M

    2013-07-01

    A new approach for representing and evaluating the flux density distribution on the absorbers of two-dimensional imaging solar concentrators is presented. The formalism accommodates any realistic solar radiance and concentrator optical error distribution. The solutions obviate the need for raytracing, and are physically transparent. Examples illustrating the method's versatility are presented for parabolic trough mirrors with both planar and tubular absorbers, Fresnel reflectors with tubular absorbers, and V-trough mirrors with planar absorbers.

  9. Piezoelectricity in Two-Dimensional Materials

    KAUST Repository

    Wu, Tao

    2015-02-25

    Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

  10. Kronecker Product of Two-dimensional Arrays

    Institute of Scientific and Technical Information of China (English)

    Lei Hu

    2006-01-01

    Kronecker sequences constructed from short sequences are good sequences for spread spectrum communication systems. In this paper we study a similar problem for two-dimensional arrays, and we determine the linear complexity of the Kronecker product of two arrays. Our result shows that similar good property on linear complexity holds for Kronecker product of arrays.

  11. Two-Dimensional Toda-Heisenberg Lattice

    Directory of Open Access Journals (Sweden)

    Vadim E. Vekslerchik

    2013-06-01

    Full Text Available We consider a nonlinear model that is a combination of the anisotropic two-dimensional classical Heisenberg and Toda-like lattices. In the framework of the Hirota direct approach, we present the field equations of this model as a bilinear system, which is closely related to the Ablowitz-Ladik hierarchy, and derive its N-soliton solutions.

  12. A novel two dimensional particle velocity sensor

    NARCIS (Netherlands)

    Pjetri, Olti; Wiegerink, Remco J.; Lammerink, Theo S.; Krijnen, Gijs J.

    2013-01-01

    In this paper we present a two wire, two-dimensional particle velocity sensor. The miniature sensor of size 1.0x2.5x0.525 mm, consisting of only two crossed wires, shows excellent directional sensitivity in both directions, thus requiring no directivity calibration, and is relatively easy to fabrica

  13. Two-dimensional microstrip detector for neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Oed, A. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Because of their robust design, gas microstrip detectors, which were developed at ILL, can be assembled relatively quickly, provided the prefabricated components are available. At the beginning of 1996, orders were received for the construction of three two-dimensional neutron detectors. These detectors have been completed. The detectors are outlined below. (author). 2 refs.

  14. Two-dimensional magma-repository interactions

    NARCIS (Netherlands)

    Bokhove, O.

    2001-01-01

    Two-dimensional simulations of magma-repository interactions reveal that the three phases --a shock tube, shock reflection and amplification, and shock attenuation and decay phase-- in a one-dimensional flow tube model have a precursor. This newly identified phase ``zero'' consists of the impact of

  15. Two-dimensional subwavelength plasmonic lattice solitons

    CERN Document Server

    Ye, F; Hu, B; Panoiu, N C

    2010-01-01

    We present a theoretical study of plasmonic lattice solitons (PLSs) formed in two-dimensional (2D) arrays of metallic nanowires embedded into a nonlinear medium with Kerr nonlinearity. We analyze two classes of 2D PLSs families, namely, fundamental and vortical PLSs in both focusing and defocusing media. Their existence, stability, and subwavelength spatial confinement are studied in detai

  16. A two-dimensional Dirac fermion microscope

    DEFF Research Database (Denmark)

    Bøggild, Peter; Caridad, Jose; Stampfer, Christoph

    2017-01-01

    in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2...

  17. Molecular assembly on two-dimensional materials

    Science.gov (United States)

    Kumar, Avijit; Banerjee, Kaustuv; Liljeroth, Peter

    2017-02-01

    Molecular self-assembly is a well-known technique to create highly functional nanostructures on surfaces. Self-assembly on two-dimensional (2D) materials is a developing field driven by the interest in functionalization of 2D materials in order to tune their electronic properties. This has resulted in the discovery of several rich and interesting phenomena. Here, we review this progress with an emphasis on the electronic properties of the adsorbates and the substrate in well-defined systems, as unveiled by scanning tunneling microscopy. The review covers three aspects of the self-assembly. The first one focuses on non-covalent self-assembly dealing with site-selectivity due to inherent moiré pattern present on 2D materials grown on substrates. We also see that modification of intermolecular interactions and molecule–substrate interactions influences the assembly drastically and that 2D materials can also be used as a platform to carry out covalent and metal-coordinated assembly. The second part deals with the electronic properties of molecules adsorbed on 2D materials. By virtue of being inert and possessing low density of states near the Fermi level, 2D materials decouple molecules electronically from the underlying metal substrate and allow high-resolution spectroscopy and imaging of molecular orbitals. The moiré pattern on the 2D materials causes site-selective gating and charging of molecules in some cases. The last section covers the effects of self-assembled, acceptor and donor type, organic molecules on the electronic properties of graphene as revealed by spectroscopy and electrical transport measurements. Non-covalent functionalization of 2D materials has already been applied for their application as catalysts and sensors. With the current surge of activity on building van der Waals heterostructures from atomically thin crystals, molecular self-assembly has the potential to add an extra level of flexibility and functionality for applications ranging

  18. A comparison of gray scale ultrasound and radionuclide imaging for the detection of focal hepatic lesions: open shutter technique.

    Science.gov (United States)

    Zatz, L M; Gouldin, J A; Hanley, G A

    1977-06-01

    A conventional B scan ultrasound unit was modified by the addition of a specially built logarithmic amplifier and a high resolution nonstorage oscilloscope, as suggested by Taylor and Carpenter. One hundred five consecutive patients submitted for radionuclide imaging of the liver were examined with ultrasound using a standardized scanning system. The ultrasound technique produced scans that were technically poor or inadequate in 37 per cent of the patients studied. In the studies in which there has been confirmation, the ultrasound diagnosis was accurate in 73 per cent and the radionuclide diagnosis was correct in 83 per cent. The combined accuracy of the two studies was 93 per cent. In 11 patients, ultrasound more clearly defined the lesions that were demonstrated by both techniques or demonstrated the nature of suspicious or equivocal areas on the radionuclide images. In 48 patients, the radionuclide scan imaged the liver more completely or demonstrated lesions more clearly than did the ultrasound examination. This specific approach to ultrasound gray scale imaging appears to be a valuable supplemental tool to radionuclide imaging, but at its present stage of development cannot replace it as a routine screening technique for hepatic disease.

  19. Electronics based on two-dimensional materials.

    Science.gov (United States)

    Fiori, Gianluca; Bonaccorso, Francesco; Iannaccone, Giuseppe; Palacios, Tomás; Neumaier, Daniel; Seabaugh, Alan; Banerjee, Sanjay K; Colombo, Luigi

    2014-10-01

    The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.

  20. Two-dimensional ranking of Wikipedia articles

    Science.gov (United States)

    Zhirov, A. O.; Zhirov, O. V.; Shepelyansky, D. L.

    2010-10-01

    The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists ab aeterno. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. While PageRank highlights very well known nodes with many ingoing links, CheiRank highlights very communicative nodes with many outgoing links. In this way the ranking becomes two-dimensional. Using CheiRank and PageRank we analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.

  1. Two-Dimensional NMR Lineshape Analysis

    Science.gov (United States)

    Waudby, Christopher A.; Ramos, Andres; Cabrita, Lisa D.; Christodoulou, John

    2016-04-01

    NMR titration experiments are a rich source of structural, mechanistic, thermodynamic and kinetic information on biomolecular interactions, which can be extracted through the quantitative analysis of resonance lineshapes. However, applications of such analyses are frequently limited by peak overlap inherent to complex biomolecular systems. Moreover, systematic errors may arise due to the analysis of two-dimensional data using theoretical frameworks developed for one-dimensional experiments. Here we introduce a more accurate and convenient method for the analysis of such data, based on the direct quantum mechanical simulation and fitting of entire two-dimensional experiments, which we implement in a new software tool, TITAN (TITration ANalysis). We expect the approach, which we demonstrate for a variety of protein-protein and protein-ligand interactions, to be particularly useful in providing information on multi-step or multi-component interactions.

  2. Towards two-dimensional search engines

    CERN Document Server

    Ermann, Leonardo; Shepelyansky, Dima L

    2011-01-01

    We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Information flow properties on PageRank-CheiRank plane are analyzed for networks of British, French and Italian Universities, Wikipedia, Linux Kernel, gene regulation and other networks. Methods of spam links control are also analyzed.

  3. Toward two-dimensional search engines

    Science.gov (United States)

    Ermann, L.; Chepelianskii, A. D.; Shepelyansky, D. L.

    2012-07-01

    We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way, the ranking of nodes becomes two dimensional which paves the way for the development of two-dimensional search engines of a new type. Statistical properties of information flow on the PageRank-CheiRank plane are analyzed for networks of British, French and Italian universities, Wikipedia, Linux Kernel, gene regulation and other networks. A special emphasis is done for British universities networks using the large database publicly available in the UK. Methods of spam links control are also analyzed.

  4. Two-Dimensional Scheduling: A Review

    Directory of Open Access Journals (Sweden)

    Zhuolei Xiao

    2013-07-01

    Full Text Available In this study, we present a literature review, classification schemes and analysis of methodology for scheduling problems on Batch Processing machine (BP with both processing time and job size constraints which is also regarded as Two-Dimensional (TD scheduling. Special attention is given to scheduling problems with non-identical job sizes and processing times, with details of the basic algorithms and other significant results.

  5. Two dimensional fermions in four dimensional YM

    CERN Document Server

    Narayanan, R

    2009-01-01

    Dirac fermions in the fundamental representation of SU(N) live on a two dimensional torus flatly embedded in $R^4$. They interact with a four dimensional SU(N) Yang Mills vector potential preserving a global chiral symmetry at finite $N$. As the size of the torus in units of $\\frac{1}{\\Lambda_{SU(N)}}$ is varied from small to large, the chiral symmetry gets spontaneously broken in the infinite $N$ limit.

  6. Two-dimensional Kagome photonic bandgap waveguide

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou;

    2000-01-01

    The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....

  7. String breaking in two-dimensional QCD

    CERN Document Server

    Hornbostel, K J

    1999-01-01

    I present results of a numerical calculation of the effects of light quark-antiquark pairs on the linear heavy-quark potential in light-cone quantized two-dimensional QCD. I extract the potential from the Q-Qbar component of the ground-state wavefunction, and observe string breaking at the heavy-light meson pair threshold. I briefly comment on the states responsible for the breaking.

  8. Two-dimensional supramolecular electron spin arrays.

    Science.gov (United States)

    Wäckerlin, Christian; Nowakowski, Jan; Liu, Shi-Xia; Jaggi, Michael; Siewert, Dorota; Girovsky, Jan; Shchyrba, Aneliia; Hählen, Tatjana; Kleibert, Armin; Oppeneer, Peter M; Nolting, Frithjof; Decurtins, Silvio; Jung, Thomas A; Ballav, Nirmalya

    2013-05-07

    A bottom-up approach is introduced to fabricate two-dimensional self-assembled layers of molecular spin-systems containing Mn and Fe ions arranged in a chessboard lattice. We demonstrate that the Mn and Fe spin states can be reversibly operated by their selective response to coordination/decoordination of volatile ligands like ammonia (NH3). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. THREE-DIMENSIONAL VISUALIZATION OF INTERCONDYLAR NOTCH BASED ON MRI TWO-DIMENSIONAL IMAGES%基于MRI二维影像下股骨髁间窝的三维可视化研究

    Institute of Scientific and Technical Information of China (English)

    李彦林; 许鹏; 韩睿; 王建伟; 何川; 王国梁; 仝路; 胡猛

    2012-01-01

    Objective To study the feasibility of virtual intercondylar notchplasty by applying MRI two-dimensional (2D) images to reconstruct three-dimensional (3D) images and measure the size of intercondylar notch. Methods Thirty healthy volunteers who had no knee joint disease and surgery history were selected. There were 15 females and 15 males with an age range of 20-30 years, weight range of 45-74 kg, and height range of 150-185 cm. They were divided into male group and female group, and the knees of each group were divided into 2 subgroups (the left group and right group). MRI scan of the left and right knees was performed, and the 2D images of MRI were imported into Mimics10.01 medical image control system for 3D reconstruction. The related anatomical data as follows were measured from the 3D digital model and analyzed by statistical software: notch width (NW), condylar width (CW), and notch width index (NWI). Then the 3D knee images of patients with anterior cruciate ligament (ACL) injury were collected between January and March 2010, and 4 patients with narrow intercondylar notch (NWI ≤ 0.2) were selected for reconstructing the 3D model of the knee and simulating the intercondylar notch plasty. Then, the volume of osteotomy in 3D model was calculated and applied in the ACL reconstruction surgery, and whether the graft had impingement with intercondylar notch or not was evaluated. Results There were significant differences in NW and CW between male group and female group (P 0.05). And there was no significant difference in NW, CW, and NWI between the left and right knees both in male group and female group (P > 0.05). After ACL reconstruction and intercondylar notchplasty, the shape of intercondylar notch became normal (NWI > 0.22), no impingement occurred between the graft and intercondylar notch under arthroscopy within 3-month follow-up. Conclusion The shape of intercondylar notch of 3D model based on MRI 2D images is similar to the real intercondylar notch. NWI

  10. Two dimensional echocardiographic detection of intraatrial masses.

    Science.gov (United States)

    DePace, N L; Soulen, R L; Kotler, M N; Mintz, G S

    1981-11-01

    With two dimensional echocardiography, a left atrial mass was detected in 19 patients. Of these, 10 patients with rheumatic mitral stenosis had a left atrial thrombus. The distinctive two dimensional echocardiographic features of left atrial thrombus included a mass of irregular nonmobile laminated echos within an enlarged atrial cavity, usually with a broad base of attachment to the posterior left atrial wall. Seven patients had a left atrial myxoma. Usually, the myxoma appeared as a mottled ovoid, sharply demarcated mobile mass attached to the interatrial septum. One patient had a right atrial angiosarcoma that appeared as a nonmobile mass extending from the inferior vena caval-right atrial junction into the right atrial cavity. One patient had a left atrial leiomyosarcoma producing a highly mobile mass attached to the lateral wall of the left atrium. M mode echocardiography detected six of the seven myxomas, one thrombus and neither of the other tumors. Thus, two dimensional echocardiography appears to be the technique of choice in the detection, localization and differentiation of intraatrial masses.

  11. COMPUTER IMAGE PROCESSING OF MICROSTRUCTURES OF GRAY CAST IRON AS A TOOL FOR QUANTITATIVE ANALYSIS OF GRAPHITE DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    A. N. Chichko

    2013-01-01

    Full Text Available Based on gray cast iron microstructure with different lengths of flaky graphite inclusions contained in GOST 3443-87 «Cast iron with various forms of graphite. Methods for determining the structure «shows the possibilities of classification of microstructures ПГд15, ПГд25, ПГд45, ПГд90, ПГд180, ПГд350, ПГд750 and ПГд1000 based on image processing techniques that allows to develop a methodology for the transition from qualitative scale of microstructures used for the analysis of the graphite phase, to quantify.

  12. Red, green, and blue gray-value shift-based approach to whole-field imaging for tissue diagnostics

    Science.gov (United States)

    Valiyambath Krishnan, Mohankumar; Vadakke Matham, Murukeshan; Krishnan, Sathiyamoorthy; Parasuraman, Padmanabhan; Joseph, James; Bhakoo, Kishore

    2012-07-01

    Identification of abnormal pathology in situ remains one of the challenges of medicine. The interpretation of tissue conditions relies mainly on optical assessment, which can be difficult due to inadequate visual differences or poor color delineation. We propose a methodology to identify regions of abnormal tissue in a targeted area based on red, green, blue (RGB) shift analysis employing a simple CCD color camera and light-emitting diode illumination in a whole-field-imaging scheme. The concept involves analysis of RGB components in an image with respect to a reference set of RGB values under different illumination wavelengths. The magnitude of the gray value shift is estimated by calculating the Euclidean distance between their normalized RGB coordinates. The shift values obtained using these concepts are thereafter used to construct pseudo-colored images with high contrast, enabling easy identification of abnormal areas in the tissue. Images processed from experiments conducted with excised Wistar rat colon sample (lightly doped with Alexafluor 488) and with simulated tumor (cancer cell pellet placed on colon) showed clear localization of tumor region. This proposed approach and methodology is expected to find potential applications for the in vivo diagnosis of disease.

  13. Viable myocardium evaluation by two dimensional speckle tracking imaging combined with adenosine stress echocardiography%二维斑点追踪技术结合腺苷负荷评价心肌存活性

    Institute of Scientific and Technical Information of China (English)

    冉红; 张平洋; 方玲玲; 马小五; 吴文芳; 冯王飞

    2013-01-01

    Objective Rcgional lcft vcntricular (LV) function could be detected by measuring peak-systolic strain by speckle tracking imaging (STI).We evaluated the value of STI combined with adenosine stress echocardiography on assessing myocardial viability in patients with myocardial infarction (MI).Methods Two dimensional echocardiography was performed at rest and after adenosine stress echocardiography (infused at 140 μg · kg-1 · min-1 over a period of 6 min) in 39 stable patients with previous MI.Peak-systolic (Speak-sys) circumferential strain,radial strain and longitudinal strain were assessed by STI.Radionuclide myocardial perfusion/metabolic imaging served as the “gold standard” to detection of myocardial viability.Results (1) There were 215 viable and 153 non-viable regions among 368abnormal motion segments out of 624 segments in 39 MI patients according to radionuclide imaging results.(2) Speak-sys was similar between viable and nonviable myocardium at rest (all P > 0.05).After adenosine infusion,radial Speak-sys [(37.98 ± 5.45) % vs.(30.22 ± 5.47) %],longitudinal Speak-sys [(-23.71 ±4.53) % vs.(-17.52 ± 4.34) %] increased significantly (P < 0.05) in viable segments compared to baseline levels and were significantly higher than in nonviable segments radial Speak-sys [(37.98 ± 5.45) %vs.(30.12±5.37)%] and longitudinal Speak-sys[(-23.71 ±4.53)% vs.(-16.95±4.62)%](P<0.05),while remained unchanged in nonviable segments before and after adenosine infusion.Circumferential Speak-sys was similar before and after adenosine infusion in both viable and nonviable segments (all P > 0.05).(3) Delta radial strain change > 9.8% has a sensitivity of 82.3% and a specificity of 81.1% whereas a delta change of longitudinal strain > 16.5% has a sensitivity of 83.5% and a specificity of 92.3% for detecting viable segments.Conclusions Speckle tracking imaging combined with adenosine stress echocardiography could serve as a new and

  14. Optical encryption of gray-level image using on-axis and 2-f digital holography with two-step phase-shifting method

    Science.gov (United States)

    Jeon, Seok Hee; Hwang, Young Gwan; Gil, Sang Keun

    2008-07-01

    In this paper we propose an encryption/decryption technique of gray-level image information using an on-axis 2-f digital holographic optical encrypting system with two-step phase-shifting method. This technique reduces the number of holograms in phase-shifting digital holography and minimizes the setup of the encryption system more than multistep phase-shifting technique. We are able to get the complete decrypted image by controlling the K-ratio which is defined as the reference beam intensity versus the object beam intensity. We remove the DC-term of the phase-shifting digital hologram to reconstruct and decrypt the original image information. Simulation results show that the proposed method can be used for encryption and decryption of a 256 gray-level image. Also, the result shows some errors of the decrypted image according to K-ratio.

  15. Triple Arterial Phase MR Imaging with Gadoxetic Acid Using a Combination of Contrast Enhanced Time Robust Angiography, Keyhole, and Viewsharing Techniques and Two-Dimensional Parallel Imaging in Comparison with Conventional Single Arterial Phase

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jeong Hee [Department of Radiology, Seoul National University Hospital, Seoul 03080 (Korea, Republic of); Department of Radiology, Seoul National University College of Medicine, Seoul 03087 (Korea, Republic of); Lee, Jeong Min [Department of Radiology, Seoul National University Hospital, Seoul 03080 (Korea, Republic of); Department of Radiology, Seoul National University College of Medicine, Seoul 03087 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03087 (Korea, Republic of); Yu, Mi Hye [Department of Radiology, Konkuk University Medical Center, Seoul 05030 (Korea, Republic of); Kim, Eun Ju [Philips Healthcare Korea, Seoul 04342 (Korea, Republic of); Han, Joon Koo [Department of Radiology, Seoul National University Hospital, Seoul 03080 (Korea, Republic of); Department of Radiology, Seoul National University College of Medicine, Seoul 03087 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03087 (Korea, Republic of)

    2016-11-01

    To determine whether triple arterial phase acquisition via a combination of Contrast Enhanced Time Robust Angiography, keyhole, temporal viewsharing and parallel imaging can improve arterial phase acquisition with higher spatial resolution than single arterial phase gadoxetic-acid enhanced magnetic resonance imaging (MRI). Informed consent was waived for this retrospective study by our Institutional Review Board. In 752 consecutive patients who underwent gadoxetic acid-enhanced liver MRI, either single (n = 587) or triple (n = 165) arterial phases was obtained in a single breath-hold under MR fluoroscopy guidance. Arterial phase timing was assessed, and the degree of motion was rated on a four-point scale. The percentage of patients achieving the late arterial phase without significant motion was compared between the two methods using the χ{sup 2} test. The late arterial phase was captured at least once in 96.4% (159/165) of the triple arterial phase group and in 84.2% (494/587) of the single arterial phase group (p < 0.001). Significant motion artifacts (score ≤ 2) were observed in 13.3% (22/165), 1.2% (2/165), 4.8% (8/165) on 1st, 2nd, and 3rd scans of triple arterial phase acquisitions and 6.0% (35/587) of single phase acquisitions. Thus, the late arterial phase without significant motion artifacts was captured in 96.4% (159/165) of the triple arterial phase group and in 79.9% (469/587) of the single arterial phase group (p < 0.001). Triple arterial phase imaging may reliably provide adequate arterial phase imaging for gadoxetic acid-enhanced liver MRI.

  16. Triple arterial phase MR imaging with gadoxetic acid using a combination of contrast enhanced time robust angiography, keyhole, and viewsharing techniques and two-dimensional parallel imaging in comparison with conventional single arterial phase

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jeong Hee; Lee, Jeong Min; Han, Joon Koo [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of); Yu, Mi Hye [Dept. of Radiology, Konkuk University Medical Center, Seoul (Korea, Republic of); Kim, Eun Ju [Philips Healthcare Korea, Seoul (Korea, Republic of)

    2016-07-15

    To determine whether triple arterial phase acquisition via a combination of Contrast Enhanced Time Robust Angiography, keyhole, temporal viewsharing and parallel imaging can improve arterial phase acquisition with higher spatial resolution than single arterial phase gadoxetic-acid enhanced magnetic resonance imaging (MRI). Informed consent was waived for this retrospective study by our Institutional Review Board. In 752 consecutive patients who underwent gadoxetic acid-enhanced liver MRI, either single (n = 587) or triple (n = 165) arterial phases was obtained in a single breath-hold under MR fluoroscopy guidance. Arterial phase timing was assessed, and the degree of motion was rated on a four-point scale. The percentage of patients achieving the late arterial phase without significant motion was compared between the two methods using the χ2 test. The late arterial phase was captured at least once in 96.4% (159/165) of the triple arterial phase group and in 84.2% (494/587) of the single arterial phase group (p < 0.001). Significant motion artifacts (score ≤ 2) were observed in 13.3% (22/165), 1.2% (2/165), 4.8% (8/165) on 1st, 2nd, and 3rd scans of triple arterial phase acquisitions and 6.0% (35/587) of single phase acquisitions. Thus, the late arterial phase without significant motion artifacts was captured in 96.4% (159/165) of the triple arterial phase group and in 79.9% (469/587) of the single arterial phase group (p < 0.001). Triple arterial phase imaging may reliably provide adequate arterial phase imaging for gadoxetic acid-enhanced liver MRI.

  17. Augmented reality simulator for training in two-dimensional echocardiography.

    Science.gov (United States)

    Weidenbach, M; Wick, C; Pieper, S; Quast, K J; Fox, T; Grunst, G; Redel, D A

    2000-02-01

    In two-dimensional echocardiography the sonographer must synthesize multiple tomographic slices into a mental three-dimensional (3D) model of the heart. Computer graphics and virtual reality environments are ideal to visualize complex 3D spatial relationships. In augmented reality (AR) applications, real and virtual image data are linked, to increase the information content. In the presented AR simulator a 3D surface model of the human heart is linked with echocardiographic volume data sets. The 3D echocardiographic data sets are registered with the heart model to establish spatial and temporal congruence. The heart model, together with an animated ultrasound sector represents a reference scenario, which displays the currently selected two-dimensional echocardiographic cutting plane calculated from the volume data set. Modifications of the cutting plane within the echocardiographic data are transferred and visualized simultaneously and in real time within the reference scenario. The trainee can interactively explore the 3D heart model and the registered 3D echocardiographic data sets by an animated ultrasound probe, whose position is controlled by an electromagnetic tracking system. The tracking system is attached to a dummy transducer and placed on a plastic puppet to give a realistic impression of a two-dimensional echocardiographic examination.

  18. Image analysis techniques and gray-level co-occurrence matrices (GLCM) for calculating bioturbation indices and characterizing biogenic sedimentary structures

    Science.gov (United States)

    Honeycutt, Chris Ebey; Plotnick, Roy

    2008-11-01

    Aspects of texture and structure in a bed resulting from bioturbation can provide valuable information about the ecology and environment at the time of deposition. However, not only the degree of bioturbation, but the structure of the burrows is important for interpreting biogenic fabrics. Here, image analysis is applied to real and artificial images of biogenic sedimentary structures. Image segmentation was applied to images of Middle Ordovician biogenic sedimentary structures from Dixon, Illinois (Pecatonica Formation), isolating the biogenic sedimentary structures. A gray-level co-occurrence matrix (GLCM) is calculated from the segmented image and eight artificial images representing different levels of image noise. Texture measures were calculated from the GLCMs and compared with identify scale and directional structural differences between the images. Principal component analysis was used to statistically group the images. Artificial images were found to be distinguishable from the real images by GLCM texture measures, and the real images differed most significantly at the largest scales.

  19. Weakly disordered two-dimensional Frenkel excitons

    Science.gov (United States)

    Boukahil, A.; Zettili, Nouredine

    2004-03-01

    We report the results of studies of the optical properties of weakly disordered two- dimensional Frenkel excitons in the Coherent Potential Approximation (CPA). An approximate complex Green's function for a square lattice with nearest neighbor interactions is used in the self-consistent equation to determine the coherent potential. It is shown that the Density of States is very much affected by the logarithmic singularities in the Green's function. Our CPA results are in excellent agreement with previous investigations by Schreiber and Toyozawa using the Monte Carlo simulation.

  20. Two-dimensional photonic crystal surfactant detection.

    Science.gov (United States)

    Zhang, Jian-Tao; Smith, Natasha; Asher, Sanford A

    2012-08-07

    We developed a novel two-dimensional (2-D) crystalline colloidal array photonic crystal sensing material for the visual detection of amphiphilic molecules in water. A close-packed polystyrene 2-D array monolayer was embedded in a poly(N-isopropylacrylamide) (PNIPAAm)-based hydrogel film. These 2-D photonic crystals placed on a mirror show intense diffraction that enables them to be used for visual determination of analytes. Binding of surfactant molecules attaches ions to the sensor that swells the PNIPAAm-based hydrogel. The resulting increase in particle spacing red shifts the 2-D diffracted light. Incorporation of more hydrophobic monomers increases the sensitivity to surfactants.

  1. Theory of two-dimensional transformations

    OpenAIRE

    Kanayama, Yutaka J.; Krahn, Gary W.

    1998-01-01

    The article of record may be found at http://dx.doi.org/10.1109/70.720359 Robotics and Automation, IEEE Transactions on This paper proposes a new "heterogeneous" two-dimensional (2D) transformation group ___ to solve motion analysis/planning problems in robotics. In this theory, we use a 3×1 matrix to represent a transformation as opposed to a 3×3 matrix in the homogeneous formulation. First, this theory is as capable as the homogeneous theory, Because of the minimal size, its implement...

  2. Two-dimensional ranking of Wikipedia articles

    CERN Document Server

    Zhirov, A O; Shepelyansky, D L

    2010-01-01

    The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists {\\it ab aeterno}. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. We analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.

  3. Mobility anisotropy of two-dimensional semiconductors

    CERN Document Server

    Lang, Haifeng; Liu, Zhirong

    2016-01-01

    The carrier mobility of anisotropic two-dimensional (2D) semiconductors under longitudinal acoustic (LA) phonon scattering was theoretically studied with the deformation potential theory. Based on Boltzmann equation with relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was deduced, which shows that the influence of effective mass to the mobility anisotropy is larger than that of deformation potential constant and elastic modulus. Parameters were collected for various anisotropic 2D materials (black phosphorus, Hittorf's phosphorus, BC$_2$N, MXene, TiS$_3$, GeCH$_3$) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio was overestimated in the past.

  4. Sums of two-dimensional spectral triples

    DEFF Research Database (Denmark)

    Christensen, Erik; Ivan, Cristina

    2007-01-01

    construct a sum of two dimensional modules which reflects some aspects of the topological dimensions of the compact metric space, but this will only give the metric back approximately. At the end we make an explicit computation of the last module for the unit interval in. The metric is recovered exactly......, the Dixmier trace induces a multiple of the Lebesgue integral but the growth of the number of eigenvalues is different from the one found for the standard differential operator on the unit interval....

  5. Binding energy of two-dimensional biexcitons

    DEFF Research Database (Denmark)

    Singh, Jai; Birkedal, Dan; Vadim, Lyssenko;

    1996-01-01

    Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....

  6. Dynamics of film. [two dimensional continua theory

    Science.gov (United States)

    Zak, M.

    1979-01-01

    The general theory of films as two-dimensional continua are elaborated upon. As physical realizations of such a model this paper examines: inextensible films, elastic films, and nets. The suggested dynamic equations have enabled us to find out the characteristic speeds of wave propagation of the invariants of external and internal geometry and formulate the criteria of instability of their shape. Also included herein is a detailed account of the equation describing the film motions beyond the limits of the shape stability accompanied by the formation of wrinkles. The theory is illustrated by examples.

  7. GRAY TONE FILTERING ON ERS-SAR IMAGES APPLIED TO CHANGE DETECTION AND MAPPING

    Directory of Open Access Journals (Sweden)

    Gilles André

    2011-05-01

    Full Text Available In SAR images, the pixel values are tightly related to physical parameters of the soil such as topography, roughness and humidity, regardless to atmospheric conditions. Therefore, SAR images may be used to detect, and quantify changes in land cover, by comparison of time series SAR data. Classical change detection techniques from SAR images are based on additive synthesis of RGB colors and arithmetic operations between images. The noisy aspect of ERS image due to the original speckle is an obstacle for available mapping and quantification of the changes. Here, statistical and morphological filters are used to reduce the speckle noise. Combined techniques of change detection and noise filtering are applied here to assess and map from ERS-SAR images the impact of regular or catastrophic flood and deforestation in the East Coast of Madagascar.

  8. Gesture Recognition Using Character Recognition Techniques on Two-dimensional Eigenspace

    OpenAIRE

    大野, 宏; 山本, 正信; Ohno, Hiroshi; Yamamoto, Masanobu

    1999-01-01

    This paper describes a novel method for gesture recognition using character recognition techniques on two-dimensional eigenspace. An image-based approach can capture human body poses in 3D motion from multiple image sequences. The sequence of poses can be reduced into a trajectory on the two-dimensional eigenspace with preserving the main features in gesture, so that the gesture recognition equals the character recognition. Experiments for the gesture recognition using some character recognit...

  9. Two-dimensional gauge theoretic supergravities

    Science.gov (United States)

    Cangemi, D.; Leblanc, M.

    1994-05-01

    We investigate two-dimensional supergravity theories, which can be built from a topological and gauge invariant action defined on an ordinary surface. One is the N = 1 supersymmetric extension of the Jackiw-Teitelboim model presented by Chamseddine in a superspace formalism. We complement the proof of Montano, Aoaki and Sonnenschein that this extension is topological and gauge invariant, based on the graded de Sitter algebra. Not only do the equations of motion correspond to the supergravity ones and do gauge transformations encompass local supersymmetries, but we also identify the ∫-theory with the superfield formalism action written by Chamseddine. Next, we show that the N = 1 supersymmetric extension of string-inspired two-dimensional dilaton gravity put forward by Park and Strominger cannot be written as a ∫-theory. As an alternative, we propose two topological and gauge theories that are based on a graded extension of the extended Poincaré algebra and satisfy a vanishing-curvature condition. Both models are supersymmetric extensions of the string-inspired dilaton gravity.

  10. Two-Dimensional Theory of Scientific Representation

    Directory of Open Access Journals (Sweden)

    A Yaghmaie

    2013-03-01

    Full Text Available Scientific representation is an interesting topic for philosophers of science, many of whom have recently explored it from different points of view. There are currently two competing approaches to the issue: cognitive and non-cognitive, and each of them claims its own merits over the other. This article tries to provide a hybrid theory of scientific representation, called Two-Dimensional Theory of Scientific Representation, which has the merits of the two accounts and is free of their shortcomings. To do this, we will argue that although scientific representation needs to use the notion of intentionality, such a notion is defined and realized in a simply structural form contrary to what cognitive approach says about intentionality. After a short introduction, the second part of the paper is devoted to introducing theories of scientific representation briefly. In the third part, the structural accounts of representation will be criticized. The next step is to introduce the two-dimensional theory which involves two key components: fixing and structural fitness. It will be argued that fitness is an objective and non-intentional relation, while fixing is intentional.

  11. Two-dimensional shape memory graphene oxide

    Science.gov (United States)

    Chang, Zhenyue; Deng, Junkai; Chandrakumara, Ganaka G.; Yan, Wenyi; Liu, Jefferson Zhe

    2016-06-01

    Driven by the increasing demand for micro-/nano-technologies, stimuli-responsive shape memory materials at nanoscale have recently attracted great research interests. However, by reducing the size of conventional shape memory materials down to approximately nanometre range, the shape memory effect diminishes. Here, using density functional theory calculations, we report the discovery of a shape memory effect in a two-dimensional atomically thin graphene oxide crystal with ordered epoxy groups, namely C8O. A maximum recoverable strain of 14.5% is achieved as a result of reversible phase transition between two intrinsically stable phases. Our calculations conclude co-existence of the two stable phases in a coherent crystal lattice, giving rise to the possibility of constructing multiple temporary shapes in a single material, thus, enabling highly desirable programmability. With an atomic thickness, excellent shape memory mechanical properties and electric field stimulus, the discovery of a two-dimensional shape memory graphene oxide opens a path for the development of exceptional micro-/nano-electromechanical devices.

  12. Three-dimensional versus two-dimensional vision in laparoscopy

    DEFF Research Database (Denmark)

    Sørensen, Stine Maya Dreier; Savran, Mona M; Konge, Lars;

    2016-01-01

    BACKGROUND: Laparoscopic surgery is widely used, and results in accelerated patient recovery time and hospital stay were compared with laparotomy. However, laparoscopic surgery is more challenging compared with open surgery, in part because surgeons must operate in a three-dimensional (3D) space...... through a two-dimensional (2D) projection on a monitor, which results in loss of depth perception. To counter this problem, 3D imaging for laparoscopy was developed. A systematic review of the literature was performed to assess the effect of 3D laparoscopy. METHODS: A systematic search of the literature...

  13. Two-Dimensional Change Detection Methods Remote Sensing Applications

    CERN Document Server

    Ilsever, Murat

    2012-01-01

    Change detection using remotely sensed images has many applications, such as urban monitoring, land-cover change analysis, and disaster management. This work investigates two-dimensional change detection methods. The existing methods in the literature are grouped into four categories: pixel-based, transformation-based, texture analysis-based, and structure-based. In addition to testing existing methods, four new change detection methods are introduced: fuzzy logic-based, shadow detection-based, local feature-based, and bipartite graph matching-based. The latter two methods form the basis for a

  14. Existence and Stability of Two-Dimensional Compact-Like Discrete Breathers in Discrete Two-Dimensional Monatomic Square Lattices

    Institute of Scientific and Technical Information of China (English)

    XU Quan; TIAN Qiang

    2007-01-01

    Two-dimensional compact-like discrete breathers in discrete two-dimensional monatomic square lattices are investigated by discussing a generafized discrete two-dimensional monatomic model.It is proven that the twodimensional compact-like discrete breathers exist not only in two-dimensional soft Ф4 potentials but also in hard two-dimensional Ф4 potentials and pure two-dimensional K4 lattices.The measurements of the two-dimensional compact-like discrete breather cores in soft and hard two-dimensional Ф4 potential are determined by coupling parameter K4,while those in pure two-dimensional K4 lattices have no coupling with parameter K4.The stabilities of the two-dimensional compact-like discrete breathers correlate closely to the coupling parameter K4 and the boundary condition of lattices.

  15. A Method for Gray-Scale Imaging of Blood Flow Using High-Frequency Ultrasound.

    Science.gov (United States)

    Yang, Jun; Pang, Chao; Song, Xue-Dong; Gao, Xuan

    2017-07-01

    This paper presents a new method that complements current techniques available in the high-frequency blood imaging field. A comprehensive scattering model was established to determine the feasibility and frequency range of the blood flow imaging of superficial organs and tissues using high-frequency ultrasound. The transmitting and receiving modes and an algorithm were designed to obtain blood flow information based on differentiation between tissues and blood flow. The system was created and tested first with a model that simulates blood flow and was then used on human tissue. A fine-scale image of a blood vessel could be obtained with this system. Moreover, this method can obtain weak blood flow signal using single pulse rather than the traditional pulse-code method and maintains a high resolution that can be matched to high-frequency structural imaging. This study provides a reliable method for further applications related to diagnoses of superficial organs.

  16. The effects of gray scale image processing on digital mammography interpretation performance.

    Science.gov (United States)

    Cole, Elodia B; Pisano, Etta D; Zeng, Donglin; Muller, Keith; Aylward, Stephen R; Park, Sungwook; Kuzmiak, Cherie; Koomen, Marcia; Pavic, Dag; Walsh, Ruth; Baker, Jay; Gimenez, Edgardo I; Freimanis, Rita

    2005-05-01

    To determine the effects of three image-processing algorithms on diagnostic accuracy of digital mammography in comparison with conventional screen-film mammography. A total of 201 cases consisting of nonprocessed soft copy versions of the digital mammograms acquired from GE, Fischer, and Trex digital mammography systems (1997-1999) and conventional screen-film mammograms of the same patients were interpreted by nine radiologists. The raw digital data were processed with each of three different image-processing algorithms creating three presentations-manufacturer's default (applied and laser printed to film by each of the manufacturers), MUSICA, and PLAHE-were presented in soft copy display. There were three radiologists per presentation. Area under the receiver operating characteristic curve for GE digital mass cases was worse than screen-film for all digital presentations. The area under the receiver operating characteristic for Trex digital mass cases was better, but only with images processed with the manufacturer's default algorithm. Sensitivity for GE digital mass cases was worse than screen film for all digital presentations. Specificity for Fischer digital calcifications cases was worse than screen film for images processed in default and PLAHE algorithms. Specificity for Trex digital calcifications cases was worse than screen film for images processed with MUSICA. Specific image-processing algorithms may be necessary for optimal presentation for interpretation based on machine and lesion type.

  17. PLANT RECOGNITION USING STEREO LEAF IMAGE USING GRAY-LEVEL CO-OCCURRENCE MATRIX

    Directory of Open Access Journals (Sweden)

    Hermawan Syahputra

    2014-01-01

    Full Text Available Adequate knowledge, such as information about the unique characteristics of each plant, is necessary to identify plant. Researchers have made plant recognition based on leaf characteristics. The leaf image-based plant recognition in view of different angles is a new challenge. In this study, the research on the plant recognition was conducted based on leaf images resulted from 3D stereo camera. The 3D images are very influential in the development of computer vision theory, which can provide more detailed information of an object. One of the information that can be obtained is about the position of the object in its image with the background as well as of the camera. One of the ways used to obtain such information is to calculate the disparity. However, this method will only tell the position of the object compared to other objects without that of range. Sum Absolute Different (SAD is a method that can be used to find the disparity value. The SAD method does not require heavy computations and long process. Before calculating the disparity, all the images should be previously segmented. The objective of this segmentation is to separate all the objects from the background. Furthermore, filtering and polynomial transformation at the results of disparity is necessary to improve the quality of resultant images. Furthermore, 22 features were extracted using GLCM features (second order statistics of images resulted from disparity improvement. The highest accuracy of match in the recognition of plant varieties was obtained at 50 cm distance and in the recognition of three plant varieties was 83.3%.

  18. Optimal excitation of two dimensional Holmboe instabilities

    CERN Document Server

    Constantinou, Navid C

    2010-01-01

    Highly stratified shear layers are rendered unstable even at high stratifications by Holmboe instabilities when the density stratification is concentrated in a small region of the shear layer. These instabilities may cause mixing in highly stratified environments. However these instabilities occur in tongues for a limited range of parameters. We perform Generalized Stability analysis of the two dimensional perturbation dynamics of an inviscid Boussinesq stratified shear layer and show that Holmboe instabilities at high Richardson numbers can be excited by their adjoints at amplitudes that are orders of magnitude larger than by introducing initially the unstable mode itself. We also determine the optimal growth that obtains for parameters for which there is no instability. We find that there is potential for large transient growth regardless of whether the background flow is exponentially stable or not and that the characteristic structure of the Holmboe instability asymptotically emerges for parameter values ...

  19. Phonon hydrodynamics in two-dimensional materials.

    Science.gov (United States)

    Cepellotti, Andrea; Fugallo, Giorgia; Paulatto, Lorenzo; Lazzeri, Michele; Mauri, Francesco; Marzari, Nicola

    2015-03-06

    The conduction of heat in two dimensions displays a wealth of fascinating phenomena of key relevance to the scientific understanding and technological applications of graphene and related materials. Here, we use density-functional perturbation theory and an exact, variational solution of the Boltzmann transport equation to study fully from first-principles phonon transport and heat conductivity in graphene, boron nitride, molybdenum disulphide and the functionalized derivatives graphane and fluorographene. In all these materials, and at variance with typical three-dimensional solids, normal processes keep dominating over Umklapp scattering well-above cryogenic conditions, extending to room temperature and more. As a result, novel regimes emerge, with Poiseuille and Ziman hydrodynamics, hitherto typically confined to ultra-low temperatures, characterizing transport at ordinary conditions. Most remarkably, several of these two-dimensional materials admit wave-like heat diffusion, with second sound present at room temperature and above in graphene, boron nitride and graphane.

  20. Probabilistic Universality in two-dimensional Dynamics

    CERN Document Server

    Lyubich, Mikhail

    2011-01-01

    In this paper we continue to explore infinitely renormalizable H\\'enon maps with small Jacobian. It was shown in [CLM] that contrary to the one-dimensional intuition, the Cantor attractor of such a map is non-rigid and the conjugacy with the one-dimensional Cantor attractor is at most 1/2-H\\"older. Another formulation of this phenomenon is that the scaling structure of the H\\'enon Cantor attractor differs from its one-dimensional counterpart. However, in this paper we prove that the weight assigned by the canonical invariant measure to these bad spots tends to zero on microscopic scales. This phenomenon is called {\\it Probabilistic Universality}. It implies, in particular, that the Hausdorff dimension of the canonical measure is universal. In this way, universality and rigidity phenomena of one-dimensional dynamics assume a probabilistic nature in the two-dimensional world.

  1. Two-dimensional position sensitive neutron detector

    Indian Academy of Sciences (India)

    A M Shaikh; S S Desai; A K Patra

    2004-08-01

    A two-dimensional position sensitive neutron detector has been developed. The detector is a 3He + Kr filled multiwire proportional counter with charge division position readout and has a sensitive area of 345 mm × 345 mm, pixel size 5 mm × 5 mm, active depth 25 mm and is designed for efficiency of 70% for 4 Å neutrons. The detector is tested with 0.5 bar 3He + 1.5 bar krypton gas mixture in active chamber and 2 bar 4He in compensating chamber. The pulse height spectrum recorded at an anode potential of 2000 V shows energy resolution of ∼ 25% for the 764 keV peak. A spatial resolution of 8 mm × 6 mm is achieved. The detector is suitable for SANS studies in the range of 0.02–0.25 Å-1.

  2. Two-dimensional heterostructures for energy storage

    Science.gov (United States)

    Pomerantseva, Ekaterina; Gogotsi, Yury

    2017-07-01

    Two-dimensional (2D) materials provide slit-shaped ion diffusion channels that enable fast movement of lithium and other ions. However, electronic conductivity, the number of intercalation sites, and stability during extended cycling are also crucial for building high-performance energy storage devices. While individual 2D materials, such as graphene, show some of the required properties, none of them can offer all properties needed to maximize energy density, power density, and cycle life. Here we argue that stacking different 2D materials into heterostructured architectures opens an opportunity to construct electrodes that would combine the advantages of the individual building blocks while eliminating the associated shortcomings. We discuss characteristics of common 2D materials and provide examples of 2D heterostructured electrodes that showed new phenomena leading to superior electrochemical performance. We also consider electrode fabrication approaches and finally outline future steps to create 2D heterostructured electrodes that could greatly expand current energy storage technologies.

  3. Rationally synthesized two-dimensional polymers.

    Science.gov (United States)

    Colson, John W; Dichtel, William R

    2013-06-01

    Synthetic polymers exhibit diverse and useful properties and influence most aspects of modern life. Many polymerization methods provide linear or branched macromolecules, frequently with outstanding functional-group tolerance and molecular weight control. In contrast, extending polymerization strategies to two-dimensional periodic structures is in its infancy, and successful examples have emerged only recently through molecular framework, surface science and crystal engineering approaches. In this Review, we describe successful 2D polymerization strategies, as well as seminal research that inspired their development. These methods include the synthesis of 2D covalent organic frameworks as layered crystals and thin films, surface-mediated polymerization of polyfunctional monomers, and solid-state topochemical polymerizations. Early application targets of 2D polymers include gas separation and storage, optoelectronic devices and membranes, each of which might benefit from predictable long-range molecular organization inherent to this macromolecular architecture.

  4. Janus Spectra in Two-Dimensional Flows

    Science.gov (United States)

    Liu, Chien-Chia; Cerbus, Rory T.; Chakraborty, Pinaki

    2016-09-01

    In large-scale atmospheric flows, soap-film flows, and other two-dimensional flows, the exponent of the turbulent energy spectra, α , may theoretically take either of two distinct values, 3 or 5 /3 , but measurements downstream of obstacles have invariably revealed α =3 . Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which α transitions from 3 to 5 /3 for the streamwise fluctuations but remains equal to 3 for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows.

  5. Local doping of two-dimensional materials

    Science.gov (United States)

    Wong, Dillon; Velasco, Jr, Jairo; Ju, Long; Kahn, Salman; Lee, Juwon; Germany, Chad E.; Zettl, Alexander K.; Wang, Feng; Crommie, Michael F.

    2016-09-20

    This disclosure provides systems, methods, and apparatus related to locally doping two-dimensional (2D) materials. In one aspect, an assembly including a substrate, a first insulator disposed on the substrate, a second insulator disposed on the first insulator, and a 2D material disposed on the second insulator is formed. A first voltage is applied between the 2D material and the substrate. With the first voltage applied between the 2D material and the substrate, a second voltage is applied between the 2D material and a probe positioned proximate the 2D material. The second voltage between the 2D material and the probe is removed. The first voltage between the 2D material and the substrate is removed. A portion of the 2D material proximate the probe when the second voltage was applied has a different electron density compared to a remainder of the 2D material.

  6. Two-dimensional fourier transform spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    DeFlores, Lauren; Tokmakoff, Andrei

    2016-10-25

    The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.

  7. Two-dimensional fourier transform spectrometer

    Science.gov (United States)

    DeFlores, Lauren; Tokmakoff, Andrei

    2013-09-03

    The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.

  8. Equivalency of two-dimensional algebras

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Gildemar Carneiro dos; Pomponet Filho, Balbino Jose S. [Universidade Federal da Bahia (UFBA), BA (Brazil). Inst. de Fisica

    2011-07-01

    Full text: Let us consider a vector z = xi + yj over the field of real numbers, whose basis (i,j) satisfy a given algebra. Any property of this algebra will be reflected in any function of z, so we can state that the knowledge of the properties of an algebra leads to more general conclusions than the knowledge of the properties of a function. However structural properties of an algebra do not change when this algebra suffers a linear transformation, though the structural constants defining this algebra do change. We say that two algebras are equivalent to each other whenever they are related by a linear transformation. In this case, we have found that some relations between the structural constants are sufficient to recognize whether or not an algebra is equivalent to another. In spite that the basis transform linearly, the structural constants change like a third order tensor, but some combinations of these tensors result in a linear transformation, allowing to write the entries of the transformation matrix as function of the structural constants. Eventually, a systematic way to find the transformation matrix between these equivalent algebras is obtained. In this sense, we have performed the thorough classification of associative commutative two-dimensional algebras, and find that even non-division algebra may be helpful in solving non-linear dynamic systems. The Mandelbrot set was used to have a pictorial view of each algebra, since equivalent algebras result in the same pattern. Presently we have succeeded in classifying some non-associative two-dimensional algebras, a task more difficult than for associative one. (author)

  9. The Gray Images of Cyclic Codes over Zp[u]/(uk+1)%环Zp[u]/(uk+1)上循环码的Gray象

    Institute of Scientific and Technical Information of China (English)

    梁华; 唐元生

    2013-01-01

    记R=Zp[u]/(uk+1),定义了从Rn到Znpkp的Gray映射.利用Gray映射的性质,研究了环R上任意长循环码.证明了环R上任意长码是循环码当且仅当它的Gray象是域Zp上的准循环码.特别的,环R上的线性循环码的Gray象是Zp上的线性准循环码.%Let R =Zp[u]/(uk+1).A Gray map from Rn to Znpkp is defined.Base on the property of Gray map,cyclic codes of arbitrary length overR are studied.It is proved that a code of arbitrary length over R is a cyclic code if and only if its Gray image is a quasi-cyclic code overZp.In particular,the Gray image of a linear cyclic code overR is a linear quasi-cyclic code over Zp.

  10. Effect analysis of three-dimensional and two-dimensional imaging systems in laparoscopic radical resection of rectal cancer%3D与2D腹腔镜直肠癌根治术的疗效分析

    Institute of Scientific and Technical Information of China (English)

    费秉元; 姜俊男; 房学东; 季福建

    2016-01-01

    Objective To compare the clinical effect of three-dimensional(3D)and two-dimensional(2D)imaging systems in laparoscopic radical resection of rectal cancer.Methods The retrospective cohort study was adopted.The clinical data of the 97 patients who underwent laparoscopic radical resection of rectal cancer at the Xinmin Branch of the China-Japan Union Hospital of Jilin University between May 2012 and December 2014 were collected.Of 97 patients,47 undergoing 3D laparoscopic radical resection of rectal cancer were allocated into the 3D group and 50 undergoing 2D laparoscopic radical resection of rectal cancer were allocated into the 2D group.The operation followed strictly tumor-free and total mesorectal excision principles.Observation indicators included:(1)surgical situations:operation time,time of deep lymph nodes dissected,volume of intraoperative blood loss,bleeding volume of obturator lymph nodes dissected,number of lymph nodes dissected,postoperative complications and duration of hospital stay.(2)Follow-up situations:follow-up using outpatient examination and telephone interview was performed to detect the survival of patients and tumor recurrence and metastasis up to December 2015.Measurement data with normal distribution were presented as-x±s and comparison between groups was analyzed using the t test.Count data were analyzed using the chi-square test.Results(1)Surgical situations:all the patients underwent successful laparoscopic radical resection of rectal cancer,without conversion to open surgery.Operation time,time of deep lymph nodes dissected,volume of intraoperative blood loss,bleeding volume of obturator lymph nodes dissected,number of lymph nodes dissected and duration of postoperative hospital stay were(134.6±18.5)minutes,(21.2±2.7)minutes,(65±20)mL,(16±3)mL,23.6±3.5,(8.2±2.3)days in the 3D group and(157.4±17.8)minutes,(25.2±2.5)minutes,(89±27)mL,(23±5)mL,20.5±2.8,(9.4±2.1)days in the 2D group,respectively,with statistically significant

  11. A TCAM-based Two-dimensional Prefix Packet Classification Algorithm

    Institute of Scientific and Technical Information of China (English)

    王志恒; 刘刚; 白英彩

    2004-01-01

    Packet classification (PC) has become the main method to support the quality of service and security of network application. And two-dimensional prefix packet classification (PPC) is the popular one. This paper analyzes the problem of ruler conflict, and then presents a TCAMbased two-dimensional PPC algorithm. This algorithm makes use of the parallelism of TCAM to lookup the longest prefix in one instruction cycle. Then it uses a memory image and associated data structures to eliminate the conflicts between rulers, and performs a fast two-dimensional PPC.Compared with other algorithms, this algorithm has the least time complexity and less space complexity.

  12. Reference values for myocardial two-dimensional strain echocardiography in a healthy pediatric and young adult cohort

    NARCIS (Netherlands)

    Marcus, K.A.; Mavinkurve-Groothuis, A.M.C.; Barends, M.; Dijk, A.P.J. van; Feuth, T.; Korte, C.L. de; Kapusta, L.

    2011-01-01

    BACKGROUND: The accurate evaluation of intrinsic myocardial contractility in children with or without congenital heart disease (CHD) has turned out to be a challenge. Two-dimensional strain echocardiographic (2DSTE) imaging or two-dimensional speckle-tracking echocardiographic imaging appears to hol

  13. A New Audio Watermarking Method Based on Discrete Cosine Transform with a Gray Image

    Directory of Open Access Journals (Sweden)

    Mohammad Ibrahim Khan

    2012-09-01

    Full Text Available Many effective watermarking algorithms have been proposed and implemented for digital images anddigital video. However, a few algorithms have been proposed for audio watermarking. This is due to thefact that, human auditory system (HAS is far more complex and sensitive than human visual system (HVS.In this research work, a new method of embedding image data into the audio signal and additive audiowatermarking algorithm based on Discrete Cosine Transformation (DCT domain is proposed. First, theoriginal audio is transformed into DCT domain. The DCT coefficients are divided into a fixed number ofsubsections and the energy of each subsection is calculated. Next, watermark is generated from image byimage processing algorithm. Watermarks are then embedded into selected peaks of highest energysubsection. Experimental results demonstrate that the watermark is inaudible and this algorithm is robustto common operations of digital audio signal processing, such as noise addition, re-sampling, requantization and so on. To evaluate the performance of the proposed audio watermarking method,subjective and objective quality tests including Bit Error Rate (BER and Signal to Noise ratio (SNR areconducted.

  14. Glutamatergic and Neuronal Dysfunction in Gray and White Matter: A Spectroscopic Imaging Study in a Large Schizophrenia Sample.

    Science.gov (United States)

    Bustillo, Juan R; Jones, Thomas; Chen, Hongji; Lemke, Nicholas; Abbott, Christopher; Qualls, Clifford; Stromberg, Shannon; Canive, Jose; Gasparovic, Charles

    2017-05-01

    Glutamine plus glutamate (Glx), as well as N-acetylaspartate compounds (NAAc, N-acetylaspartate plus N-acetyl-aspartyl-glutamate), a marker of neuronal viability, can be quantified with proton magnetic resonance spectroscopy (1H-MRS). We used 1H-MRS imaging to assess Glx and NAAc, as well as total-choline (glycerophospho-choline plus phospho-choline), myo-inositol and total-creatine (creatine plus phosphocreatine) from an axial supraventricular slab of gray matter (GM, medial-frontal and medial-parietal) and white matter (WM, bilateral-frontal and bilateral-parietal) voxels. Schizophrenia subjects (N = 104) and healthy controls (N = 97) with a broad age range (16 to 65) were studied. In schizophrenia, Glx was increased in GM (P schizophrenia. In patients, total creatine decreased with age in WM (P schizophrenia group (NAAc, P schizophrenia. Later in the illness, disease progression is suggested by increased cortical compaction without neuronal loss (elevated NAAc) and reduced axonal integrity (lower NAAc). Furthermore, this process is associated with fundamentally altered relationships between neurometabolite concentrations and cognitive function in schizophrenia. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. On numerical evaluation of two-dimensional phase integrals

    DEFF Research Database (Denmark)

    Lessow, H.; Rusch, W.; Schjær-Jacobsen, Hans

    1975-01-01

    The relative advantages of several common numerical integration algorithms used in computing two-dimensional phase integrals are evaluated.......The relative advantages of several common numerical integration algorithms used in computing two-dimensional phase integrals are evaluated....

  16. SCAPS, a two-dimensional ion detector for mass spectrometer

    Science.gov (United States)

    Yurimoto, Hisayoshi

    2014-05-01

    Faraday Cup (FC) and electron multiplier (EM) are of the most popular ion detector for mass spectrometer. FC is used for high-count-rate ion measurements and EM can detect from single ion. However, FC is difficult to detect lower intensities less than kilo-cps, and EM loses ion counts higher than Mega-cps. Thus, FC and EM are used complementary each other, but they both belong to zero-dimensional detector. On the other hand, micro channel plate (MCP) is a popular ion signal amplifier with two-dimensional capability, but additional detection system must be attached to detect the amplified signals. Two-dimensional readout for the MCP signals, however, have not achieve the level of FC and EM systems. A stacked CMOS active pixel sensor (SCAPS) has been developed to detect two-dimensional ion variations for a spatial area using semiconductor technology [1-8]. The SCAPS is an integrated type multi-detector, which is different from EM and FC, and is composed of more than 500×500 pixels (micro-detectors) for imaging of cm-area with a pixel of less than 20 µm in square. The SCAPS can be detected from single ion to 100 kilo-count ions per one pixel. Thus, SCAPS can be accumulated up to several giga-count ions for total pixels, i.e. for total imaging area. The SCAPS has been applied to stigmatic ion optics of secondary ion mass spectrometer, as a detector of isotope microscope [9]. The isotope microscope has capabilities of quantitative isotope images of hundred-micrometer area on a sample with sub-micrometer resolution and permil precision, and of two-dimensional mass spectrum on cm-scale of mass dispersion plane of a sector magnet with ten-micrometer resolution. The performance has been applied to two-dimensional isotope spatial distribution for mainly hydrogen, carbon, nitrogen and oxygen of natural (extra-terrestrial and terrestrial) samples and samples simulated natural processes [e.g. 10-17]. References: [1] Matsumoto, K., et al. (1993) IEEE Trans. Electron Dev. 40

  17. Perspective: Two-dimensional resonance Raman spectroscopy

    Science.gov (United States)

    Molesky, Brian P.; Guo, Zhenkun; Cheshire, Thomas P.; Moran, Andrew M.

    2016-11-01

    Two-dimensional resonance Raman (2DRR) spectroscopy has been developed for studies of photochemical reaction mechanisms and structural heterogeneity in complex systems. The 2DRR method can leverage electronic resonance enhancement to selectively probe chromophores embedded in complex environments (e.g., a cofactor in a protein). In addition, correlations between the two dimensions of the 2DRR spectrum reveal information that is not available in traditional Raman techniques. For example, distributions of reactant and product geometries can be correlated in systems that undergo chemical reactions on the femtosecond time scale. Structural heterogeneity in an ensemble may also be reflected in the 2D spectroscopic line shapes of both reactive and non-reactive systems. In this perspective article, these capabilities of 2DRR spectroscopy are discussed in the context of recent applications to the photodissociation reactions of triiodide and myoglobin. We also address key differences between the signal generation mechanisms for 2DRR and off-resonant 2D Raman spectroscopies. Most notably, it has been shown that these two techniques are subject to a tradeoff between sensitivity to anharmonicity and susceptibility to artifacts. Overall, recent experimental developments and applications of the 2DRR method suggest great potential for the future of the technique.

  18. Janus spectra in two-dimensional flows

    CERN Document Server

    Liu, Chien-Chia; Chakraborty, Pinaki

    2016-01-01

    In theory, large-scale atmospheric flows, soap-film flows and other two-dimensional flows may host two distinct types of turbulent energy spectra---in one, $\\alpha$, the spectral exponent of velocity fluctuations, equals $3$ and the fluctuations are dissipated at the small scales, and in the other, $\\alpha=5/3$ and the fluctuations are dissipated at the large scales---but measurements downstream of obstacles have invariably revealed $\\alpha = 3$. Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which $\\alpha$ has transitioned from $3$ to $5/3$ for the streamwise fluctuations but remains equal to $3$ for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows...

  19. Comparative Two-Dimensional Fluorescence Gel Electrophoresis.

    Science.gov (United States)

    Ackermann, Doreen; König, Simone

    2018-01-01

    Two-dimensional comparative fluorescence gel electrophoresis (CoFGE) uses an internal standard to increase the reproducibility of coordinate assignment for protein spots visualized on 2D polyacrylamide gels. This is particularly important for samples, which need to be compared without the availability of replicates and thus cannot be studied using differential gel electrophoresis (DIGE). CoFGE corrects for gel-to-gel variability by co-running with the sample proteome a standardized marker grid of 80-100 nodes, which is formed by a set of purified proteins. Differentiation of reference and analyte is possible by the use of two fluorescent dyes. Variations in the y-dimension (molecular weight) are corrected by the marker grid. For the optional control of the x-dimension (pI), azo dyes can be used. Experiments are possible in both vertical and horizontal (h) electrophoresis devices, but hCoFGE is much easier to perform. For data analysis, commercial software capable of warping can be adapted.

  20. Two-dimensional hexagonal semiconductors beyond graphene

    Science.gov (United States)

    Nguyen, Bich Ha; Hieu Nguyen, Van

    2016-12-01

    The rapid and successful development of the research on graphene and graphene-based nanostructures has been substantially enlarged to include many other two-dimensional hexagonal semiconductors (THS): phosphorene, silicene, germanene, hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDCs) such as MoS2, MoSe2, WS2, WSe2 as well as the van der Waals heterostructures of various THSs (including graphene). The present article is a review of recent works on THSs beyond graphene and van der Waals heterostructures composed of different pairs of all THSs. One among the priorities of new THSs compared to graphene is the presence of a non-vanishing energy bandgap which opened up the ability to fabricate a large number of electronic, optoelectronic and photonic devices on the basis of these new materials and their van der Waals heterostructures. Moreover, a significant progress in the research on TMDCs was the discovery of valley degree of freedom. The results of research on valley degree of freedom and the development of a new technology based on valley degree of freedom-valleytronics are also presented. Thus the scientific contents of the basic research and practical applications os THSs are very rich and extremely promising.

  1. Two-Dimensional Phononic Crystals: Disorder Matters.

    Science.gov (United States)

    Wagner, Markus R; Graczykowski, Bartlomiej; Reparaz, Juan Sebastian; El Sachat, Alexandros; Sledzinska, Marianna; Alzina, Francesc; Sotomayor Torres, Clivia M

    2016-09-14

    The design and fabrication of phononic crystals (PnCs) hold the key to control the propagation of heat and sound at the nanoscale. However, there is a lack of experimental studies addressing the impact of order/disorder on the phononic properties of PnCs. Here, we present a comparative investigation of the influence of disorder on the hypersonic and thermal properties of two-dimensional PnCs. PnCs of ordered and disordered lattices are fabricated of circular holes with equal filling fractions in free-standing Si membranes. Ultrafast pump and probe spectroscopy (asynchronous optical sampling) and Raman thermometry based on a novel two-laser approach are used to study the phononic properties in the gigahertz (GHz) and terahertz (THz) regime, respectively. Finite element method simulations of the phonon dispersion relation and three-dimensional displacement fields furthermore enable the unique identification of the different hypersonic vibrations. The increase of surface roughness and the introduction of short-range disorder are shown to modify the phonon dispersion and phonon coherence in the hypersonic (GHz) range without affecting the room-temperature thermal conductivity. On the basis of these findings, we suggest a criteria for predicting phonon coherence as a function of roughness and disorder.

  2. Two-dimensional topological photonic systems

    Science.gov (United States)

    Sun, Xiao-Chen; He, Cheng; Liu, Xiao-Ping; Lu, Ming-Hui; Zhu, Shi-Ning; Chen, Yan-Feng

    2017-09-01

    The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems.

  3. Radiation effects on two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Walker, R.C. II; Robinson, J.A. [Department of Materials Science, Penn State, University Park, PA (United States); Center for Two-Dimensional Layered Materials, Penn State, University Park, PA (United States); Shi, T. [Department of Mechanical and Nuclear Engineering, Penn State, University Park, PA (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Silva, E.C. [GlobalFoundries, Malta, NY (United States); Jovanovic, I. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)

    2016-12-15

    The effects of electromagnetic and particle irradiation on two-dimensional materials (2DMs) are discussed in this review. Radiation creates defects that impact the structure and electronic performance of materials. Determining the impact of these defects is important for developing 2DM-based devices for use in high-radiation environments, such as space or nuclear reactors. As such, most experimental studies have been focused on determining total ionizing dose damage to 2DMs and devices. Total dose experiments using X-rays, gamma rays, electrons, protons, and heavy ions are summarized in this review. We briefly discuss the possibility of investigating single event effects in 2DMs based on initial ion beam irradiation experiments and the development of 2DM-based integrated circuits. Additionally, beneficial uses of irradiation such as ion implantation to dope materials or electron-beam and helium-beam etching to shape materials have begun to be used on 2DMs and are reviewed as well. For non-ionizing radiation, such as low-energy photons, we review the literature on 2DM-based photo-detection from terahertz to UV. The majority of photo-detecting devices operate in the visible and UV range, and for this reason they are the focus of this review. However, we review the progress in developing 2DMs for detecting infrared and terahertz radiation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Photodetectors based on two dimensional materials

    Science.gov (United States)

    Zheng, Lou; Zhongzhu, Liang; Guozhen, Shen

    2016-09-01

    Two-dimensional (2D) materials with unique properties have received a great deal of attention in recent years. This family of materials has rapidly established themselves as intriguing building blocks for versatile nanoelectronic devices that offer promising potential for use in next generation optoelectronics, such as photodetectors. Furthermore, their optoelectronic performance can be adjusted by varying the number of layers. They have demonstrated excellent light absorption, enabling ultrafast and ultrasensitive detection of light in photodetectors, especially in their single-layer structure. Moreover, due to their atomic thickness, outstanding mechanical flexibility, and large breaking strength, these materials have been of great interest for use in flexible devices and strain engineering. Toward that end, several kinds of photodetectors based on 2D materials have been reported. Here, we present a review of the state-of-the-art in photodetectors based on graphene and other 2D materials, such as the graphene, transition metal dichalcogenides, and so on. Project supported by the National Natural Science Foundation of China (Nos. 61377033, 61574132, 61504136) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences.

  5. Asymptotics for Two-dimensional Atoms

    DEFF Research Database (Denmark)

    Nam, Phan Thanh; Portmann, Fabian; Solovej, Jan Philip

    2012-01-01

    We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E^{\\TF}(\\lambd......We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E......^{\\TF}(\\lambda)$ is given by a Thomas-Fermi type variational problem and $c^{\\rm H}\\approx -2.2339$ is an explicit constant. We also show that the radius of a two-dimensional neutral atom is unbounded when $Z\\to \\infty$, which is contrary to the expected behavior of three-dimensional atoms....

  6. Predicting Two-Dimensional Silicon Carbide Monolayers.

    Science.gov (United States)

    Shi, Zhiming; Zhang, Zhuhua; Kutana, Alex; Yakobson, Boris I

    2015-10-27

    Intrinsic semimetallicity of graphene and silicene largely limits their applications in functional devices. Mixing carbon and silicon atoms to form two-dimensional (2D) silicon carbide (SixC1-x) sheets is promising to overcome this issue. Using first-principles calculations combined with the cluster expansion method, we perform a comprehensive study on the thermodynamic stability and electronic properties of 2D SixC1-x monolayers with 0 ≤ x ≤ 1. Upon varying the silicon concentration, the 2D SixC1-x presents two distinct structural phases, a homogeneous phase with well dispersed Si (or C) atoms and an in-plane hybrid phase rich in SiC domains. While the in-plane hybrid structure shows uniform semiconducting properties with widely tunable band gap from 0 to 2.87 eV due to quantum confinement effect imposed by the SiC domains, the homogeneous structures can be semiconducting or remain semimetallic depending on a superlattice vector which dictates whether the sublattice symmetry is topologically broken. Moreover, we reveal a universal rule for describing the electronic properties of the homogeneous SixC1-x structures. These findings suggest that the 2D SixC1-x monolayers may present a new "family" of 2D materials, with a rich variety of properties for applications in electronics and optoelectronics.

  7. Two-dimensional visualization of cluster beams by microchannel plates

    CERN Document Server

    Khoukaz, Alfons; Grieser, Silke; Hergemöller, Ann-Katrin; Köhler, Esperanza; Täschner, Alexander

    2013-01-01

    An advanced technique for a two-dimensional real time visualization of cluster beams in vacuum as well as of the overlap volume of cluster beams with particle accelerator beams is presented. The detection system consists of an array of microchannel plates (MCP) in combination with a phosphor screen which is read out by a CCD camera. This setup together with the ionization of a cluster beam by an electron or ion beam allows for spatial resolved investigations of the cluster beam position, size, and intensity. Moreover, since electrically uncharged clusters remain undetected, the operation in an internal beam experiment opens the way to monitor the overlap region and thus the position and size of an accelerator beam crossing an originally electrically neutral cluster jet. The observed intensity distribution of the recorded image is directly proportional to the convolution of the spatial ion beam and cluster beam intensities and is by this a direct measure of the two-dimensional luminosity distribution. This inf...

  8. Two-Dimensional Impact Reconstruction Method for Rail Defect Inspection

    Directory of Open Access Journals (Sweden)

    Jie Zhao

    2014-01-01

    Full Text Available The safety of train operating is seriously menaced by the rail defects, so it is of great significance to inspect rail defects dynamically while the train is operating. This paper presents a two-dimensional impact reconstruction method to realize the on-line inspection of rail defects. The proposed method utilizes preprocessing technology to convert time domain vertical vibration signals acquired by wireless sensor network to space signals. The modern time-frequency analysis method is improved to reconstruct the obtained multisensor information. Then, the image fusion processing technology based on spectrum threshold processing and node color labeling is proposed to reduce the noise, and blank the periodic impact signal caused by rail joints and locomotive running gear. This method can convert the aperiodic impact signals caused by rail defects to partial periodic impact signals, and locate the rail defects. An application indicates that the two-dimensional impact reconstruction method could display the impact caused by rail defects obviously, and is an effective on-line rail defects inspection method.

  9. Two dimensional discriminant neighborhood preserving embedding in face recognition

    Science.gov (United States)

    Pang, Meng; Jiang, Jifeng; Lin, Chuang; Wang, Binghui

    2015-03-01

    One of the key issues of face recognition is to extract the features of face images. In this paper, we propose a novel method, named two-dimensional discriminant neighborhood preserving embedding (2DDNPE), for image feature extraction and face recognition. 2DDNPE benefits from four techniques, i.e., neighborhood preserving embedding (NPE), locality preserving projection (LPP), image based projection and Fisher criterion. Firstly, NPE and LPP are two popular manifold learning techniques which can optimally preserve the local geometry structures of the original samples from different angles. Secondly, image based projection enables us to directly extract the optimal projection vectors from twodimensional image matrices rather than vectors, which avoids the small sample size problem as well as reserves useful structural information embedded in the original images. Finally, the Fisher criterion applied in 2DDNPE can boost face recognition rates by minimizing the within-class distance, while maximizing the between-class distance. To evaluate the performance of 2DDNPE, several experiments are conducted on the ORL and Yale face datasets. The results corroborate that 2DDNPE outperforms the existing 1D feature extraction methods, such as NPE, LPP, LDA and PCA across all experiments with respect to recognition rate and training time. 2DDNPE also delivers consistently promising results compared with other competing 2D methods such as 2DNPP, 2DLPP, 2DLDA and 2DPCA.

  10. Imaging of olfactory bulb and gray matter volumes in brain areas associated with olfactory function in patients with Parkinson's disease and multiple system atrophy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun, E-mail: shchen_2013@163.com [Department of Neurology, The First Affiliated Hospital of Guangzhou Medical College (China); Tan, Hong-yu, E-mail: honhyutan@21cn.com [Department of Neurology, The First Affiliated Hospital of Guangzhou Medical College (China); Wu, Zhuo-hua, E-mail: zhh88@126.com [Department of Neurology, The First Affiliated Hospital of Guangzhou Medical College (China); Sun, Chong-peng, E-mail: Suncp2002@gmail.com [Imaging Center, The First Affiliated Hospital of Guangzhou Medical College (China); He, Jian-xun, E-mail: xundog@163.com [Imaging Center, The First Affiliated Hospital of Guangzhou Medical College (China); Li, Xin-chun, E-mail: xinchunli@163.com [Imaging Center, The First Affiliated Hospital of Guangzhou Medical College (China); Shao, Ming, E-mail: yimshao@126.com [Department of Neurology, The First Affiliated Hospital of Guangzhou Medical College (China)

    2014-03-15

    We explored if magnetic resonance imaging sequences might aid in the clinical differential diagnosis of idiopathic Parkinson's disease (IPD) and multiple system atrophy (MSA). We measured the volumes of the olfactory bulb, the olfactory tract, and olfaction-associated cortical gray matter in 20 IPD patients, 14 MSA patients, and 12 normal subjects, using high-resolution magnetic resonance imaging sequences in combination with voxel-based statistical analysis. We found that, compared to normal subjects and MSA patients, the volumes of the olfactory bulb and tract were significantly reduced in IPD patients. The gray matter volume of IPD patients decreased in the following order: the olfactory area to the right of the piriform cortex, the right amygdala, the left entorhinal cortex, and the left occipital lobe. Further, the total olfactory bulb volume of IPD patients was associated with the duration of disease. The entorhinal cortical gray matter volume was negatively associated with the UPDRS III score. Conclusion: Structural volumes measured by high-resolution magnetic resonance imaging may potentially be used for differential diagnosis of IPD from MSA.

  11. Imaging features of gray-scale and contrast-enhanced color doppler US for the differentiation of transient renal arterial ischemia and arterial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byung Kwan; Kim Seung Hyup [Seoul National University Hospital, Seoul (Korea, Republic of); Moon, Min Hwan; Jung, Sung Il [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2005-09-15

    To characterize the imaging features on gray-scale and contrast-enhanced color Doppler US images which differentiate renal ischemia from renal infarction. The segmental renal arteries of eight healthy rabbits were surgically ligated. In four of these rabbits, the ligated renal artery was released 60 minutes after arterial occlusion to cause transient ischemia. In the remaining four rabbits, the arterial ligation was retained to cause a permanent infarction. The gray-scale and contrast-enhanced color Doppler US imaging features of the involved renal parenchymal of both ischemia and infarction groups were compared with respect to the presence or absence of parenchymal swelling, echogenicity changes, tissue loss and perfusion defects. Parenchyma swelling, echogenic changes, tissue loss and perfusion defects were found to be more extensive in the infarction than the ischemia group. The hyperechoic areas reperfused with blood flow recovered normal echogenicity and perfusion, whereas the hyperechoic areas without reperfusion became renal infarcts. Gray-scale and contrast-enhanced color Doppler US showed that the hyperechoic areas with reperfusion may reverse to normal parenchyma and allow the differentiation of renal ischemia from renal infarction.

  12. Interaction of two-dimensional magnetoexcitons

    Science.gov (United States)

    Dumanov, E. V.; Podlesny, I. V.; Moskalenko, S. A.; Liberman, M. A.

    2017-04-01

    We study interaction of the two-dimensional magnetoexcitons with in-plane wave vector k→∥ = 0 , taking into account the influence of the excited Landau levels (ELLs) and of the external electric field perpendicular to the surface of the quantum well and parallel to the external magnetic field. It is shown that the account of the ELLs gives rise to the repulsion between the spinless magnetoexcitons with k→∥ = 0 in the Fock approximation, with the interaction constant g decreasing inverse proportional to the magnetic field strength B (g (0) ∼ 1 / B) . In the presence of the perpendicular electric field the Rashba spin-orbit coupling (RSOC), Zeeman splitting (ZS) and nonparabolicity of the heavy-hole dispersion law affect the Landau quantization of the electrons and holes. They move along the new cyclotron orbits, change their Coulomb interactions and cause the interaction between 2D magnetoexcitons with k→∥ = 0 . The changes of the Coulomb interactions caused by the electrons and by the holes moving with new cyclotron orbits are characterized by some coefficients, which in the absence of the electric field turn to be unity. The differences between these coefficients of the electron-hole pairs forming the magnetoexcitons determine their affinities to the interactions. The interactions between the homogeneous, semihomogeneous and heterogeneous magnetoexcitons forming the symmetric states with the same signs of their affinities are attractive whereas in the case of different sign affinities are repulsive. In the heterogeneous asymmetric states the interactions have opposite signs in comparison with the symmetric states. In all these cases the interaction constant g have the dependence g (0) 1 /√{ B} .

  13. Two-dimensional materials and their prospects in transistor electronics.

    Science.gov (United States)

    Schwierz, F; Pezoldt, J; Granzner, R

    2015-05-14

    During the past decade, two-dimensional materials have attracted incredible interest from the electronic device community. The first two-dimensional material studied in detail was graphene and, since 2007, it has intensively been explored as a material for electronic devices, in particular, transistors. While graphene transistors are still on the agenda, researchers have extended their work to two-dimensional materials beyond graphene and the number of two-dimensional materials under examination has literally exploded recently. Meanwhile several hundreds of different two-dimensional materials are known, a substantial part of them is considered useful for transistors, and experimental transistors with channels of different two-dimensional materials have been demonstrated. In spite of the rapid progress in the field, the prospects of two-dimensional transistors still remain vague and optimistic opinions face rather reserved assessments. The intention of the present paper is to shed more light on the merits and drawbacks of two-dimensional materials for transistor electronics and to add a few more facets to the ongoing discussion on the prospects of two-dimensional transistors. To this end, we compose a wish list of properties for a good transistor channel material and examine to what extent the two-dimensional materials fulfill the criteria of the list. The state-of-the-art two-dimensional transistors are reviewed and a balanced view of both the pros and cons of these devices is provided.

  14. Pneumatization of the temporal portion of the zygomatic arch: The contribution of computed tomography to the reconstruction in volumetric two-dimensional and three-dimensional, with the aid of image rendering protocols

    Directory of Open Access Journals (Sweden)

    C M Romano-Sousa

    2015-01-01

    Full Text Available Pneumatization refers to the asymptomatic development of cavities containing air within them. There is great variability in the extent of temporal bone pneumatization. Nevertheless, in a few cases it extends to the zygomatic process. Images are presented in which the panoramic radiograph and hypocycloidal tomography reveal this variation from the norm, to which professionals must be alert, since the images may simulate the presence of pathology. In this case report we describe the presence of pneumatization of the petrous and zygomatic portions of the temporal bone, demonstrating the contribution of CT to reconstruction in volumetric 2D and 3D, with the aid of image rendering protocols.

  15. Displaying gray shades in liquid crystal displays

    Indian Academy of Sciences (India)

    T N Ruckmongathan

    2003-08-01

    Quality of image in a display depends on the contrast, colour, resolution and the number of gray shades. A large number of gray shades is necessary to display images without any contour lines. These contours are due to limited number of gray shades in the display causing abrupt changes in grayness of the image, while the original image has a gradual change in brightness. Amplitude modulation has the capability to display a large number of gray shades with minimum number of time intervals [1,2]. This paper will cover the underlying principle of amplitude modulation, some variants and its extension to multi-line addressing. Other techniques for displaying gray shades in passive matrix displays are reviewed for the sake of comparison.

  16. Comparison of a new glasses-free three-dimensional screen, a passive-glasses three-dimensional screen, and a two-dimensional imaging system for use in laparoscopic surgery

    Science.gov (United States)

    Salimpour, Pedram; Kim, Cadence A.; LaMorte, Wayne; Birkett, Desmond H.; Babayan, Richard K.

    1997-05-01

    New video imaging technologies have significantly improved the development of minimally invasive surgical and laparoscopic procedures. The next step in this evolution, the advent of more complex procedures performed under minimally invasive conditions, demands a greater need for accurate depth perception; further improvements in imaging technology as well as instrumentation are needed for the surgeon to perform difficult manipulative tasks with the same skill, accuracy, and speed as in open surgery. Two different techniques are currently available to produce 3-dimensional image: the 'with glasses' technique and the 'glasses-free' technique. The purpose of this experiment is twofold. First, to objectively compare the 3-D images created by the 'glasses-free' monitor, the passive glasses 3-D system, and a 2-D monitor. The second objective was to subjectively assess the quality of each screen as perceived by the operator.

  17. Equation of State of the Two-Dimensional Hubbard Model

    Science.gov (United States)

    Cocchi, Eugenio; Miller, Luke A.; Drewes, Jan H.; Koschorreck, Marco; Pertot, Daniel; Brennecke, Ferdinand; Köhl, Michael

    2016-04-01

    The subtle interplay between kinetic energy, interactions, and dimensionality challenges our comprehension of strongly correlated physics observed, for example, in the solid state. In this quest, the Hubbard model has emerged as a conceptually simple, yet rich model describing such physics. Here we present an experimental determination of the equation of state of the repulsive two-dimensional Hubbard model over a broad range of interactions 0 ≲U /t ≲20 and temperatures, down to kBT /t =0.63 (2 ) using high-resolution imaging of ultracold fermionic atoms in optical lattices. We show density profiles, compressibilities, and double occupancies over the whole doping range, and, hence, our results constitute benchmarks for state-of-the-art theoretical approaches.

  18. 边缘地旅游形象的层次构建--以肇庆为例%Two-dimensional Construction of Tourism Image in Fringe Zone---A Case of Zhaoqing

    Institute of Scientific and Technical Information of China (English)

    廖继武

    2013-01-01

    The tourism image is not clear in fringe zone because of the property of connection and transition,which affects the spread of tourism image.The contraction of tourism image should be from the perspective of the property of fringe zone.Taking the fringe zone in the Pearl River Delta - Zhaoqing as a case,this paper studies the construction method of tourism image in fringe zone and the impaction on the tourism image from the fringe zone.The nature of fringe zone can produce a double impact on the tourism image.One of the impaction is to make the tourism image deviating from whole tourism image in the region;the oth-er is a shielding effect,assimilation effect and compression effect,which makes it hard for tourists to perceive the tourism image. The building of tourist image needs to study comprehensively the factors of natural conditions,history,culture,economy and so-ciety from two levels of core and peripheral markets.The tourism image in Zhaoqing should include“beautiful landscape in Zhaoqing,the origin of Guangfu culture”and “The capital of China ink stone,the famous tourism city of the Pearl River Delta”.%边缘地因过渡交接属性而使旅游形象不鲜明,影响旅游形象传播,需要从边缘属性提炼旅游形象。以珠三角边缘地---肇庆为案例,实证分析了边缘地对旅游形象的影响及旅游形象的构建方法。边缘属性对旅游形象产生双重影响,使旅游形象偏离区域整体形象,同时产生屏蔽作用、同化作用与挤压作用,使旅游形象不易被感知。旅游形象构建需要综合自然条件、历史文化与经济社会等因素,从核心与外围市场两个层次构建。肇庆应重点打造“山水肇庆、广府之源”与“中国砚都、珠三角旅游名城”的旅游形象。

  19. Ultrafast two dimensional infrared chemical exchange spectroscopy

    Science.gov (United States)

    Fayer, Michael

    2011-03-01

    The method of ultrafast two dimensional infrared (2D IR) vibrational echo spectroscopy is described. Three ultrashort IR pulses tuned to the frequencies of the vibrational transitions of interest are directed into the sample. The interaction of these pulses with the molecular vibrational oscillators produces a polarization that gives rise to a fourth pulse, the vibrational echo. The vibrational echo pulse is combined with another pulse, the local oscillator, for heterodyne detection of the signal. For fixed time between the second and third pulses, the waiting time, the first pulse is scanned. Two Fourier transforms of the data yield a 2D IR spectrum. The waiting time is increased, and another spectrum is obtained. The change in the 2D IR spectra with increased waiting time provides information on the time evolution of the structure of the molecular system under observation. In a 2D IR chemical exchange experiment, two species A and B, are undergoing chemical exchange. A's are turning into B's, and B's are turning into A's, but the overall concentrations of the species are not changing. The kinetics of the chemical exchange on the ground electronic state under thermal equilibrium conditions can be obtained 2D IR spectroscopy. A vibration that has a different frequency for the two species is monitored. At very short time, there will be two peaks on the diagonal of the 2D IR spectrum, one for A and one for B. As the waiting time is increased, chemical exchange causes off-diagonal peaks to grow in. The time dependence of the growth of these off-diagonal peaks gives the chemical exchange rate. The method is applied to organic solute-solvent complex formation, orientational isomerization about a carbon-carbon single bond, migration of a hydrogen bond from one position on a molecule to another, protein structural substate interconversion, and water hydrogen bond switching between ions and water molecules. This work was supported by the Air Force Office of Scientific

  20. 基于多尺度二维小波变换的静脉图像融合%Vein Image Fusion Based on Two-dimensional Wavelet Multi-scale Transform

    Institute of Scientific and Technical Information of China (English)

    欧锋; 黄丹飞

    2015-01-01

    Venous blood vessels visible image detail is rich but vascular hazy outline;Venous blood vessels infrared image contour obviously but lack of details;Aiming at the shortcomings of the single vein image, this paper proposes a vein image fusion method based on multi-scale wavelet transform,the fusion image retain the source image for more infor-mation,richer details,clearer outline,better visual effect,provide very good auxiliary effect for clinical venipuncture.%静脉可见光图像血管细节较丰富,但血管轮廓模糊;静脉红外图像血管轮廓明显,但细节欠缺。针对单一静脉图像存在的不足,提出了一种基于多尺度二维小波变换的静脉图像融合方法,通过实验证实融合后的静脉图像保留了源图像更多的信息,静脉血管细节丰富、轮廓清晰、视觉效果良好,为临床静脉穿刺提供辅助作用,具有很好的临床应用价值。

  1. Myocardial deformation imaging by two-dimensional speckle-tracking echocardiography in comparison to late gadolinium enhancement cardiac magnetic resonance for analysis of myocardial fibrosis in severe aortic stenosis.

    Science.gov (United States)

    Hoffmann, Rainer; Altiok, Ertunc; Friedman, Zvi; Becker, Michael; Frick, Michael

    2014-10-01

    Myocardial deformation analysis by speckle-tracking echocardiography (STE) has been used for analysis of myocardial viability and myocardial fibrosis. Patients with severe aortic stenosis are known to develop myocardial fibrosis. This study evaluated the association between myocardial fibrosis determined by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) and 2-dimensional STE in patients with severe aortic stenosis. In 30 patients (78±7 years) with severe aortic stenosis (mean gradient 53±21 mm Hg), peak systolic circumferential strain based on 2-dimensional echocardiographic parasternal short-axis views and peak systolic longitudinal strain based on apical views were determined for analysis of regional function. LGE CMR was performed to define the amount of fibrosis in each segment within 24 hours of echocardiography. Relative amount of fibrosis was determined based on LGE CMR as gray-scale threshold 6 SDs above the mean signal intensity of the normal remote myocardium. There was a decrease in LGE from base to apex (14.4±8.7% for basal segments, 3.4±3.0% for midventricular segments, and 2.1±3.0% for apical segments; pmyocardial deformation expressed as peak systolic longitudinal strain from base to apex (-11.6±7.0% for basal segments, -16.9±6.5% for midventricular segments, and -17.4±7.7% for apical segments; p=0.001). There was a negative correlation between the amount of myocardial fibrosis determined by LGE CMR and peak systolic longitudinal strain for the total left ventricle (r=-0.538, p=0.007). Myocardial fibrosis defined as LGE>10% could be identified by peak systolic longitudinal strain less than -11.6%, with a sensitivity of 65% and a specificity of 75% (area under the receiver operating characteristic curve 0.69). In conclusion, myocardial fibrosis increases from apical to basal left ventricular segments in patients with severe aortic stenosis. There is an association between severity of myocardial fibrosis defined by LGE CMR

  2. Two-dimensional visualization of cluster beams by microchannel plates

    Energy Technology Data Exchange (ETDEWEB)

    Khoukaz, A., E-mail: khoukaz@uni-muenster.de; Bonaventura, D.; Grieser, S.; Hergemöller, A.-K.; Köhler, E.; Täschner, A.

    2014-01-21

    An advanced technique for a two-dimensional real time visualization of cluster beams in a vacuum as well as of the overlap volume of cluster beams with particle accelerator beams is presented. The detection system consists of an array of microchannel plates (MCPs) in combination with a phosphor screen which is read out by a CCD camera. This setup together with the ionization of a cluster beam by an electron or ion beam allows for spatial resolved investigations of the cluster beam position, size, and intensity. Moreover, since electrically uncharged clusters remain undetected, the operation in an internal beam experiment opens the way to monitor the overlap region and thus the position and size of an accelerator beam crossing an originally electrically neutral cluster jet. The observed intensity distribution of the recorded image is directly proportional to the convolution of the spatial ion beam and cluster beam intensities and is by this a direct measure of the two-dimensional luminosity distribution. This information can directly be used for the reconstruction of vertex positions as well as for an input for numerical simulations of the reaction zone. The spatial resolution of the images is dominated by the granularity of the complete MCP device and was found to be in the order of σ≈100μm. -- Highlights: • We present a MCP system for a 2D real time visualization of cluster target beams. • With this device the vertex region of storage ring experiments can be investigated. • Time resolved 2D information about the target thickness distribution is accessible. • A spatial resolution of the MCP device of 0.1 mm was achieved. • The presented MCP system also allows for measurements on cluster masses.

  3. WAVELET BASED CONTENT BASED IMAGE RETRIEVAL USING COLOR AND TEXTURE FEATURE EXTRACTION BY GRAY LEVEL COOCURENCE MATRIX AND COLOR COOCURENCE MATRIX

    Directory of Open Access Journals (Sweden)

    Jeyanthi Prabhu

    2014-01-01

    Full Text Available In this study we proposes an effective content based image retrieval by color and texture based on wavelet coefficient method to achieve good retrieval in efficiency. Color feature extraction is done by color Histogram. The texture feature extraction is acquired by Gray Level Coocurence Matrix (GLCM or Color Coocurence Matrix (CCM. This study provides better result for image retrieval by integrated features. Feature extraction by color Histogram, texture by GLCM, texture by CCM are compared in terms of precision performance measure.

  4. Three-dimensional isotropic fat-suppressed proton density-weighted MRI at 3 tesla using a T/R-coil can replace multiple plane two-dimensional sequences in knee imaging

    Energy Technology Data Exchange (ETDEWEB)

    Homsi, R.; Luetkens, J.A. [Bonn Univ. (Germany). Dept. of Radiology; Gieseke, J. [Philips Healthcare, Hamburg (Germany); and others

    2016-10-15

    To evaluate whether a 3D proton density-weighted fat-suppressed sequence (PDwFS) of the knee is able to replace multiplanar 2D-PDwFS. 52 patients (26 men, mean age: 41.9±14.5 years) underwent magnetic resonance imaging (MRI) of the knee at 3.0 Tesla using a T/R-coil. The imaging protocol included 3 planes of 2D-PDwFS (acquisition time (AT): 6:40 min; voxel sizes: 0.40-0.63 x 0.44-0.89 x 3 mm{sup 3}) and a 3D-PDwFS (AT: 6:31 min; voxel size: 0.63 x 0.68 x 0.63 mm{sup 3}). Homogeneity of fat suppression (HFS), artifacts, and image sharpness (IS) were evaluated on a 5-point scale (5[excellent] - 1[non-diagnostic]). The sum served as a measure for the overall image quality (OIQ). Contrast ratios (CR) compared to popliteal muscle were calculated for the meniscus (MEN), anterior (ACL) and posterior cruciate ligaments (PCL). In 13 patients who underwent arthroscopic knee surgery, two radiologists evaluated the presence of meniscal, ligamental and cartilage lesions to estimate the sensitivity and specificity of lesion detection. The CR was higher in the ACL, PCL and MEN in 3D- PDwFS compared to 2D-PDwFS (p<0.01 for ACL and PCL; p=0.07 for MEN). Compared to 2D images, the OIQ was rated higher in 3D-PDwFS images (p<0.01) due to fewer artifacts and HFS despite the lower IS (p<0.01). The sensitivity and specificity of lesion detection in 3D- and 2D-PDwFS were similar. Compared to standard multiplanar 2D-PDwFS knee imaging, isotropic high spatial resolution 3D-PDwFS of the knee at 3.0T can be acquired with high image quality in a reasonable scan time. Multiplanar reformations in arbitrary planes may serve as an additional benefit of 3D-PDwFS.

  5. Optimal Padding for the Two-Dimensional Fast Fourier Transform

    Science.gov (United States)

    Dean, Bruce H.; Aronstein, David L.; Smith, Jeffrey S.

    2011-01-01

    One-dimensional Fast Fourier Transform (FFT) operations work fastest on grids whose size is divisible by a power of two. Because of this, padding grids (that are not already sized to a power of two) so that their size is the next highest power of two can speed up operations. While this works well for one-dimensional grids, it does not work well for two-dimensional grids. For a two-dimensional grid, there are certain pad sizes that work better than others. Therefore, the need exists to generalize a strategy for determining optimal pad sizes. There are three steps in the FFT algorithm. The first is to perform a one-dimensional transform on each row in the grid. The second step is to transpose the resulting matrix. The third step is to perform a one-dimensional transform on each row in the resulting grid. Steps one and three both benefit from padding the row to the next highest power of two, but the second step needs a novel approach. An algorithm was developed that struck a balance between optimizing the grid pad size with prime factors that are small (which are optimal for one-dimensional operations), and with prime factors that are large (which are optimal for two-dimensional operations). This algorithm optimizes based on average run times, and is not fine-tuned for any specific application. It increases the amount of times that processor-requested data is found in the set-associative processor cache. Cache retrievals are 4-10 times faster than conventional memory retrievals. The tested implementation of the algorithm resulted in faster execution times on all platforms tested, but with varying sized grids. This is because various computer architectures process commands differently. The test grid was 512 512. Using a 540 540 grid on a Pentium V processor, the code ran 30 percent faster. On a PowerPC, a 256x256 grid worked best. A Core2Duo computer preferred either a 1040x1040 (15 percent faster) or a 1008x1008 (30 percent faster) grid. There are many industries that

  6. 二维斑点追踪成像技术在心脏疾病中的临床应用进展%Clinical application progress of two - dimensional speckle tracking imaging in cardiac diseases

    Institute of Scientific and Technical Information of China (English)

    李子卓; 方理刚

    2011-01-01

    目的 斑点追踪成像技术(STI)是新近发展起来的一项超声技术,其无角度依赖性,可以定量评价心肌的长轴、短轴、圆周的运动以及扭转运动,本文对STI技术在心脏疾病中的临床应用进展进行综述.%Speckle tracking imaging ( STI ) is a new ultrasonic technique in recent years, it takes the advantage of independency on the angle of insonation, and it can quantitatively assess the longitudinal, radial, circumferential and torsional function of left ventricle. This paper reviews the clinical application progress of STI in cardiac diseases.

  7. The Chandrasekhar's Equation for Two-Dimensional Hypothetical White Dwarfs

    CERN Document Server

    De, Sanchari

    2014-01-01

    In this article we have extended the original work of Chandrasekhar on the structure of white dwarfs to the two-dimensional case. Although such two-dimensional stellar objects are hypothetical in nature, we strongly believe that the work presented in this article may be prescribed as Master of Science level class problem for the students in physics.

  8. Beginning Introductory Physics with Two-Dimensional Motion

    Science.gov (United States)

    Huggins, Elisha

    2009-01-01

    During the session on "Introductory College Physics Textbooks" at the 2007 Summer Meeting of the AAPT, there was a brief discussion about whether introductory physics should begin with one-dimensional motion or two-dimensional motion. Here we present the case that by starting with two-dimensional motion, we are able to introduce a considerable…

  9. Spatiotemporal surface solitons in two-dimensional photonic lattices.

    Science.gov (United States)

    Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S

    2007-11-01

    We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice.

  10. Explorative data analysis of two-dimensional electrophoresis gels

    DEFF Research Database (Denmark)

    Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine;

    2004-01-01

    Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...

  11. Mechanics of Apparent Horizon in Two Dimensional Dilaton Gravity

    CERN Document Server

    Cai, Rong-Gen

    2016-01-01

    In this article, we give a definition of apparent horizon in a two dimensional general dilaton gravity theory. With this definition, we construct the mechanics of the apparent horizon by introducing a quasi-local energy of the theory. Our discussion generalizes the apparent horizons mechanics in general spherically symmetric spactimes in four or higher dimensions to the two dimensional dilaton gravity case.

  12. Topological aspect of disclinations in two-dimensional crystals

    Institute of Scientific and Technical Information of China (English)

    Qi Wei-Kai; Zhu Tao; Chen Yong; Ren Ji-Rong

    2009-01-01

    By using topological current theory, this paper studies the inner topological structure of disclinations during the melting of two-dimensional systems. From two-dimensional elasticity theory, it finds that there are topological currents for topological defects in homogeneous equation. The evolution of disclinations is studied, and the branch conditions for generating, annihilating, crossing, splitting and merging of disclinations are given.

  13. 基于压缩感知的双基SAR二维高分辨成像算法%Two-Dimensional High Resolution Bistatic SAR Imaging Algorithm Based on Compressed Sensing

    Institute of Scientific and Technical Information of China (English)

    李晶; 张顺生; 常俊飞

    2012-01-01

    双基地合成孔径雷达(SAR)由于收发分置,具有广阔的应用前景,但常规的频域算法不仅面临距离史双根号问题,而且数据采集受Nyquist 理论限制,数据量大.近年来提出的压缩感知(CS)理论指出,在一定条件下可以从很少的采样点中以很大的概率重建原始未知稀疏信号.本文将CS理论与双基地SAR模型相结合,提出一种基于CS的双基地SAR二维高分辨成像算法.该算法将二维随机降采样回波数据作为测量值,根据发射信号构造距离向测量矩阵,通过方位向多普勒相位因子构建方位向测量矩阵,利用CS恢复算法对目标进行了分维重建.仿真结果与性能分析表明,该算法在严重欠采样情况下仍能完好的重建原始目标,而且对噪声具有一定的鲁棒性和免疫性.与传统双基SAR成像算法相比,该算法具有更高的分辨率,成像结果峰值更加尖锐,峰值旁瓣比(PLSR)和积分旁瓣比(ILSR)都较低,而且采样率低、数据量少,具有一定的有效性和实用性.%The bistatic SAR, when transmitter and receiver move along nonparallel tracks with unequal velocities, has the potential for various applications. But the double-square-root term of range history and a large amount of echo storage are two basic challenges of traditional frequency domain imaging for bistatic SAR. Recent theory of Compressed Sensing (CS) suggests that exact recovery of an unknown sparse signal can be achieved from few measurements with overwhelming probability. In this paper, a novel bistatic SAR high resolution imaging algorithm is proposed based on CS theory and the model of bistatic SAR. In the novel algorithm, the 2-D random down-sampling echo data is as measurement value and the targets are reconstructed via CS in the range and azimuth direction, respectively. The simulation results show that the targets can be perfectly reconstructed by only using few down-sampling echo data instead of all numbers of

  14. Tilted Two-Dimensional Array Multifocus Confocal Raman Microspectroscopy.

    Science.gov (United States)

    Yabumoto, Sohshi; Hamaguchi, Hiro-O

    2017-07-18

    A simple and efficient two-dimensional multifocus confocal Raman microspectroscopy featuring the tilted-array technique is demonstrated. Raman scattering from a 4 × 4 square foci array passing through a 4 × 4 confocal pinhole array is tilted with a periscope. The tilted array of Raman scattering signals is dispersed by an imaging spectrograph onto a CCD detector, giving 16 independent Raman spectra formed as 16 bands with different heights on the sensor. Use of a state-of-the-art imaging spectrograph enables high-precision wavenumber duplicability of the 16 spectra. This high duplicability makes the simultaneously obtained spectra endurable for multivariate spectral analyses, which is demonstrated by a singular value decomposition analysis for Raman spectra of liquid indene. Although the present implementation attains only 16 measurement points, the number of points can be extended to larger than 100 without any technical leaps. Limit of parallelization depends on the interval of measurement points as well as the performance of the optical system. Criteria for finding the maximum feasible number are discussed.

  15. Two-Dimensional Nonlinear Finite Element Analysis of CMC Microstructures

    Science.gov (United States)

    Mital, Subodh K.; Goldberg, Robert K.; Bonacuse, Peter J.

    2012-01-01

    A research program has been developed to quantify the effects of the microstructure of a woven ceramic matrix composite and its variability on the effective properties and response of the material. In order to characterize and quantify the variations in the microstructure of a five harness satin weave, chemical vapor infiltrated (CVI) SiC/SiC composite material, specimens were serially sectioned and polished to capture images that detailed the fiber tows, matrix, and porosity. Open source quantitative image analysis tools were then used to isolate the constituents, from which two dimensional finite element models were generated which approximated the actual specimen section geometry. A simplified elastic-plastic model, wherein all stress above yield is redistributed to lower stress regions, is used to approximate the progressive damage behavior for each of the composite constituents. Finite element analyses under in-plane tensile loading were performed to examine how the variability in the local microstructure affected the macroscopic stress-strain response of the material as well as the local initiation and progression of damage. The macroscopic stress-strain response appeared to be minimally affected by the variation in local microstructure, but the locations where damage initiated and propagated appeared to be linked to specific aspects of the local microstructure.

  16. Rapid parametric mapping of the longitudinal relaxation time T1 using two-dimensional variable flip angle magnetic resonance imaging at 1.5 Tesla, 3 Tesla, and 7 Tesla.

    Science.gov (United States)

    Dieringer, Matthias A; Deimling, Michael; Santoro, Davide; Wuerfel, Jens; Madai, Vince I; Sobesky, Jan; von Knobelsdorff-Brenkenhoff, Florian; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2014-01-01

    Visual but subjective reading of longitudinal relaxation time (T1) weighted magnetic resonance images is commonly used for the detection of brain pathologies. For this non-quantitative measure, diagnostic quality depends on hardware configuration, imaging parameters, radio frequency transmission field (B1+) uniformity, as well as observer experience. Parametric quantification of the tissue T1 relaxation parameter offsets the propensity for these effects, but is typically time consuming. For this reason, this study examines the feasibility of rapid 2D T1 quantification using a variable flip angles (VFA) approach at magnetic field strengths of 1.5 Tesla, 3 Tesla, and 7 Tesla. These efforts include validation in phantom experiments and application for brain T1 mapping. T1 quantification included simulations of the Bloch equations to correct for slice profile imperfections, and a correction for B1+. Fast gradient echo acquisitions were conducted using three adjusted flip angles for the proposed T1 quantification approach that was benchmarked against slice profile uncorrected 2D VFA and an inversion-recovery spin-echo based reference method. Brain T1 mapping was performed in six healthy subjects, one multiple sclerosis patient, and one stroke patient. Phantom experiments showed a mean T1 estimation error of (-63±1.5)% for slice profile uncorrected 2D VFA and (0.2±1.4)% for the proposed approach compared to the reference method. Scan time for single slice T1 mapping including B1+ mapping could be reduced to 5 seconds using an in-plane resolution of (2×2) mm2, which equals a scan time reduction of more than 99% compared to the reference method. Our results demonstrate that rapid 2D T1 quantification using a variable flip angle approach is feasible at 1.5T/3T/7T. It represents a valuable alternative for rapid T1 mapping due to the gain in speed versus conventional approaches. This progress may serve to enhance the capabilities of parametric MR based lesion detection and

  17. Invariant Subspaces of the Two-Dimensional Nonlinear Evolution Equations

    Directory of Open Access Journals (Sweden)

    Chunrong Zhu

    2016-11-01

    Full Text Available In this paper, we develop the symmetry-related methods to study invariant subspaces of the two-dimensional nonlinear differential operators. The conditional Lie–Bäcklund symmetry and Lie point symmetry methods are used to construct invariant subspaces of two-dimensional differential operators. We first apply the multiple conditional Lie–Bäcklund symmetries to derive invariant subspaces of the two-dimensional operators. As an application, the invariant subspaces for a class of two-dimensional nonlinear quadratic operators are provided. Furthermore, the invariant subspace method in one-dimensional space combined with the Lie symmetry reduction method and the change of variables is used to obtain invariant subspaces of the two-dimensional nonlinear operators.

  18. Measurements of fiber orientation in two-dimensional fiber suspension flow using image-processing method; Gazo shoriho ni yoru sen`i gan`yutai no nijigen nagare ni okeru sen`i haiko no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Chono, S.; Tanoue, S.; Iemoto, Y. [Fukui University, Fukui (Japan). Faculty of Engineering

    1998-10-25

    Orientation profiles of fibers in fiber suspension flow between two parallel plates with a square cylinder on the center axis was studied by using the computer image analysis. The orientational order parameter S decreases near the square cylinder because the flow changes its direction and also a wake is developed, while it is large near the channel wall owing to high shear deformation. The preferred angle and S decrease in the downstream vicinity of the square cylinder, and reach fully-developed values at a farther area. S along the channel center axis increases with increasing a fiber concentration and the Reynolds number. The size of a square cylinder has an effect on the fiber orientation near the cylinder. Since a stagnation region and a large wake are developed before and after a cylinder for a viscoelastic fluid, a lower value of S near the cylinder is obtained for the viscoelastic fluid compared to that for a Newtonian fluid. At a downstream area, however, the viscoelastic fluid gives a higher values of S. 21 refs., 14 figs., 1 tab.

  19. Comparative proteomics and metallomics studies in Arabidopsis thaliana leaf tissues: evaluation of the selenium addition in transgenic and nontransgenic plants using two-dimensional difference gel electrophoresis and laser ablation imaging.

    Science.gov (United States)

    Maciel, Bruna C M; Barbosa, Herbert S; Pessôa, Gustavo S; Salazar, Marcela M; Pereira, Gonçalo A G; Gonçalves, Danieli C; Ramos, Carlos H I; Arruda, Marco A Z

    2014-04-01

    The main goal of this work is to evaluate some differential protein species in transgenic (T) and nontransgenic (NT) Arabidopsis thaliana plants after their cultivation in the presence or absence of sodium selenite. The transgenic line was obtained through insertion of CaMV 35S controlling nptII gene. Comparative proteomics through 2D-DIGE is carried out in four different groups (NT × T; NT × Se-NT (where Se is selenium); Se-NT × Se-T, and T × Se-T). Although no differential proteins are achieved in the T × Se-T group, for the others, 68 differential proteins (by applying a regulation factor ≥1.5) are achieved, and 27 of them accurately characterized by ESI-MS/MS. These proteins are classified into metabolism, energy, signal transduction, disease/defense categories, and some of them are involved in the glycolysis pathway-Photosystems I and II and ROS combat. Additionally, laser ablation imaging is used for evaluating the Se and sulfur distribution in leaves of different groups, corroborating some results obtained and related to proteins involved in the glycolysis pathway. From these results, it is possible to conclude that the genetic modification also confers to the plant resistance to oxidative stress.

  20. Value of tissue Doppler-derived Tei index and two-dimensional speckle tracking imaging derived longitudinal strain on predicting outcome of patients with light-chain cardiac amyloidosis.

    Science.gov (United States)

    Liu, Dan; Hu, Kai; Herrmann, Sebastian; Cikes, Maja; Ertl, Georg; Weidemann, Frank; Störk, Stefan; Nordbeck, Peter

    2017-06-01

    Prognosis of patients with light-chain cardiac amyloidosis (AL-CA) is poor. Speckle tracking imaging (STI) derived longitudinal deformation parameters and Doppler-derived left ventricular (LV) Tei index are valuable predictors of outcome in patients with AL-CA. We estimated the prognostic utility of Tei index and deformation parameters in 58 comprehensively phenotyped patients with AL-CA after a median follow-up of 365 days (quartiles 121, 365 days). The primary end point was all-cause mortality. 19 (33%) patients died during follow-up. Tei index (0.89 ± 0.29 vs. 0.61 ± 0.16, p < 0.001) and E to global early diastolic strain rate ratio (E/GLSRdias) were higher while global longitudinal systolic strain (GLSsys) was lower in non-survivors than in survivors (all p < 0.05). Tei index, NYHA functional class, GLSsys and E/GLSRdias were independent predictors of all-cause mortality risk, and Tei index ≥0.9 (HR 7.01, 95% CI 2.43-20.21, p < 0.001) was the best predictor of poor outcome. Combining Tei index and GLSsys yielded the best results on predicting death within 1 year (100% with Tei index ≥0.9 and GLSsys ≤13%) or survival (95% with Tei index ≤0.9 and GLSsys ≥13%). We conclude that 1-year mortality risk in AL-CA patients can be reliably predicted using Tei index or deformation parameters, with combined analysis offering best performance.

  1. Content Based Medical Image Retrieval with Texture Content Using Gray Level Co-occurrence Matrix and K-Means Clustering Algorithms

    Directory of Open Access Journals (Sweden)

    K. R. Chandran

    2012-01-01

    Full Text Available Problem statement: Recently, there has been a huge progress in collection of varied image databases in the form of digital. Most of the users found it difficult to search and retrieve required images in large collections. In order to provide an effective and efficient search engine tool, the system has been implemented. In image retrieval system, there is no methodologies have been considered directly to retrieve the images from databases. Instead of that, various visual features that have been considered indirect to retrieve the images from databases. In this system, one of the visual features such as texture that has been considered indirectly into images to extract the feature of the image. That featured images only have been considered for the retrieval process in order to retrieve exact desired images from the databases. Approach: The aim of this study is to construct an efficient image retrieval tool namely, “Content Based Medical Image Retrieval with Texture Content using Gray Level Co-occurrence Matrix (GLCM and k-Means Clustering algorithms”. This image retrieval tool is capable of retrieving images based on the texture feature of the image and it takes into account the Pre-processing, feature extraction, Classification and retrieval steps in order to construct an efficient retrieval tool. The main feature of this tool is used of GLCM of the extracting texture pattern of the image and k-means clustering algorithm for image classification in order to improve retrieval efficiency. The proposed image retrieval system consists of three stages i.e., segmentation, texture feature extraction and clustering process. In the segmentation process, preprocessing step to segment the image into blocks is carried out. A reduction in an image region to be processed is carried out in the texture feature extraction process and finally, the extracted image is clustered using the k-means algorithm. The proposed system is employed for domain

  2. Short-range magnetic order in two-dimensional cobalt-ferrite nanoparticle assemblies

    NARCIS (Netherlands)

    Georgescu, M; Viota, J.L.; Klokkenburg, M.; Erne, B.H.; Vanmaekelbergh, D.; Zeijlmans Van Emmichoven, P.A.

    2008-01-01

    Magnetic order in two-dimensional islands of spherical 21 nm cobalt-ferrite (CoFe2O4) nanoparticles is studied by magnetic force microscopy and spectroscopy. Images obtained at a temperature of 105 K clearly reveal the presence of repulsive and attractive areas on top of the islands. Monte Carlo

  3. Two-dimensional discrete gap breathers in a two-dimensional discrete diatomic Klein-Gordon lattice

    Institute of Scientific and Technical Information of China (English)

    XU Quan; QIANG Tian

    2009-01-01

    We study the existence and stability of two-dimensional discrete breathers in a two-dimensional discrete diatomic Klein-Gordon lattice consisting of alternating light and heavy atoms, with nearest-neighbor harmonic coupling.Localized solutions to the corresponding nonlinear differential equations with frequencies inside the gap of the linear wave spectrum, i.e. two-dimensional gap breathers, are investigated numerically. The numerical results of the corresponding algebraic equations demonstrate the possibility of the existence of two-dimensional gap breathers with three types of symmetries, i.e., symmetric, twin-antisymmetric and single-antisymmetric. Their stability depends on the nonlinear on-site potential (soft or hard), the interaction potential (attractive or repulsive)and the center of the two-dimensional gap breather (on a light or a heavy atom).

  4. Two-Dimensional Strain Imaging for Investigating Left Ventricular Torsion in Patients with Coronary Artery Disease%超声二维应变技术对冠心病患者左心室扭转运动的研究

    Institute of Scientific and Technical Information of China (English)

    吴灵敏; 杨莉; 方思华; 邱琼

    2011-01-01

    Objective To detect left ventricular torsional changes in patients with coronary artery disease(CAD)by two-dimensional strain imaging, and to study its clinical implication.Methods Fifty-two patients with coronary artery disease and 31 control subjects were enrolled.LVEF was measured with Simpson method using two-dimentional echocardiography.High frame rate two-dimensional dynamic images were recorded from the left ventricular short-axis views at the basal and apical levels.Using two dimensional strain software,The peak basal and apical rotation (Rot-base, Rot-apex) in basal and apical plane and peak left ventricular torsion(LV-tor)were caculated using Echo PAC software.Results Rot-base, Rot-apex and LV-tor were not significantly different between coronary artery disease and control groups (P>0.05).Compared with the control group, Rot-base, Rot-apex and LV-tor were significantly lower in the 3-vessel disease subgroup (P<0.05) ,No significant difference was found for LVEF in ACD and contral groups (P>0.05).Conclusions Left ventricular torsion was impaired in patients with extensive myocardial ischemia.Left ventricular torsional changes detected by two-dimensional strain imaging may be used as an early index of left ventricular dysfunction in patients with coronary artery disease.%目的 运用超声二维应变技术检测冠心病患者左心室扭转运动的变化并探讨其临床意义.方法 冠心病组52例,对照组31例.常规测定左室射血分数(LVEF).采集高频二维动态图像,运用二维应变软件获得左心室短轴基底部、心尖部旋转角度峰值(Rot-base、Rot-apex)及左心室扭转角度峰值(LV-tor).结果 冠心病组与对照组的Rot-base、Rot-apex及LV-tor均无显著性差异(P>0.05);亚组分析显示:支病变亚组的Rot-base、Rot-apex及LV-tor显著低于对照组(P0.05).结论 范围较广的心肌缺m可引起左心室扭转运动减弱;应用二维应变技术检测左心室扭转运动变化可早期发现

  5. Longitudinal two dimensional strain rate imaging is superior to tissue Doppler imaging in predicting echocardiographic response in cardiac resynchronization therapy%二维斑点追踪显像技术预测心脏再同步治疗的疗效

    Institute of Scientific and Technical Information of China (English)

    史浩颖; 舒先红; 汪芳; 陈灏珠; 刘少稳

    2009-01-01

    Objective The aim of this study was to investigate the ability of longitudinal strain and strain rate imaging by two dimensional speckle tracking in predicting echocardiographic response under cardiac resynchronization therapy (CRT),in comparison with tissue Doppler imaging (TDI). Methods Fifty patients suffering from heart failure,who received CRT,were selected. TDI and two dimensional speckle tracking ima ging in addition to standard echocardiography were performed prior to CRT. The average value of peak longitu dinal strain in 12 left ventricular (LV) segments (Strain-12), the standard deviation of time to peak longitudinal strain in 12 LV segments (Tstrain-SD) and the standard deviation of time to the end of longitudinal systolic strain rate in 6 basal LV segments (Tsr-SD) were calculated. Patients were classified as echocardiographic re sponders if the LV end-systolic volume (LVESV) was reduced > 15% compared with baseline volumes. Re sults No significant difference was seen in baseline Ts-SD,Strain-12 and Tstrain-SD between nonresponders and responders. However, the Tsr-SD was much higher in responders than nonresponders[ (95. 9 ±33. 0)% vs (64. 8 ±39. 6)%,P15%或左心室射血分数(LVEF)绝对值增加>5%的患者.结果 CRT有效组起搏前左心室射血前时间显著长于无效组[(146.0±34.5)ms对(123.5±32.0)ms,P0.05),而CRT有效组的应变率结束时间标准差(Tsr-SD)显著高于无效组(P0.05),而CRT有效组的左心室12节段纵轴反向应变总和(Pstrain-12)显著高于无效组[(12.5±7.9)%对(7.1±8.4)%,P<0.05].将140.5 ms作为截点值,左心室射血前时间预测超声心动图有效的敏感性和特异性分别为63%和79%,将70.7 ms作为截点值,Tsr-SD预测CRT有效的敏感性和特异性分别为73%和65%.结论 常规超声心动图参数中仅左心室射血前时间能预测CRT疗效,二维斑点追踪显像技术的部分参数预测CRT疗效优于组织多普勒.

  6. Non-linear excitation of quantum emitters in two-dimensional hexagonal boron nitride

    CERN Document Server

    Schell, Andreas W; Takashima, Hideaki; Takeuchi, Shigeki; Aharonovich, Igor

    2016-01-01

    Two-photon absorption is an important non-linear process employed for high resolution bio-imaging and non-linear optics. In this work we realize two-photon excitation of a quantum emitter embedded in a two-dimensional material. We examine defects in hexagonal boron nitride and show that the emitters exhibit similar spectral and quantum properties under one-photon and two-photon excitation. Furthermore, our findings are important to deploy two-dimensional hexagonal boron nitride for quantum non-linear photonic applications.

  7. Super-Resolution and De-convolution for Single/Multi Gray Scale Images Using SIFT Algorithm

    OpenAIRE

    Ritu Soni; Siddharth Singh Chouhan

    2014-01-01

    This paper represent a Blind algorithm that restore the blurred images for single image and multi-image blur de-convolution and multi-image super-resolution on low-resolution images deteriorated by additive white Gaussian noise ,the aliasing and linear space-invariant. Image De-blurring is a field of Image Processing in which recovering an original and sharp image from a corrupted image. Proposed method is based on alternating minimization algorithm with respect to unidentifie...

  8. 暗背景下低灰度图像的实时增强%Real-Time Enhancement Method of Low Gray Image Under Dark Background

    Institute of Scientific and Technical Information of China (English)

    黄梅; 吴志勇; 梁敏华; 于建军; 管目强

    2011-01-01

    灰度图像由于光照等原因往往存在着较暗区域,并且这些区域的图像细节无法直接识别.针对这种现象,提出了一种基于局部统计增强的改进算法,并有效结合子块部分重叠的思想,实现了暗背景下低灰度图像的实时增强.与传统直方图均衡化增强方法相比,该方法保留了较亮区域的视觉特性,且对噪声的增强相对较弱.在TMS320DM642实时图像处理系统上的验证结果表明,该方法能取得非常好的显示效果,并且处理时间为每帧8 ms左右,完全满足实时性要求.%Dark areas often exist in gray image as light and other reasons, hence, in these areas the image detail can not be directly identified.So an improved image enhancement algorithm based on local statistics and partially overlapped sub-block ideas is proposed in this paper.The proposed algorithm can achieve real-time enhancement of low gray image under dark background.Compared with traditional histogram equalization method, the new algorithm not only reserves the visual characteristics of bright region but also brings relatively weak noise enhancement Experimental results tested on TMS320DM642 real-time image processing system show that the proposed algorithm obtains excellent display performance, and the processing time for each frame is around 8 ms, which satisfies the real-time requirement completely.

  9. Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway

    Science.gov (United States)

    2012-09-01

    ER D C/ CH L TR -1 2 -2 0 Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway C oa st al a n d H yd ra u lic s La b or at...distribution is unlimited. ERDC/CHL TR-12-20 September 2012 Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway Stephen H. Scott, Jeremy A...A two-dimensional Adaptive Hydraulics (AdH) hydrodynamic model was developed to simulate the Moose Creek Floodway. The Floodway is located

  10. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    Directory of Open Access Journals (Sweden)

    Nikola Stefanović

    2007-06-01

    Full Text Available In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic leadership style, leadership theory researchers use two dimensional matrices. The two-dimensional matrices define leadership styles on the basis of different parameters. By using these parameters, one can identify two-dimensional styles.

  11. Quantifying leaf venation patterns: two-dimensional maps.

    Science.gov (United States)

    Rolland-Lagan, Anne-Gaëlle; Amin, Mira; Pakulska, Malgosia

    2009-01-01

    The leaf vasculature plays crucial roles in transport and mechanical support. Understanding how vein patterns develop and what underlies pattern variation between species has many implications from both physiological and evolutionary perspectives. We developed a method for extracting spatial vein pattern data from leaf images, such as vein densities and also the sizes and shapes of the vein reticulations. We used this method to quantify leaf venation patterns of the first rosette leaf of Arabidopsis thaliana throughout a series of developmental stages. In particular, we characterized the size and shape of vein network areoles (loops), which enlarge and are split by new veins as a leaf develops. Pattern parameters varied in time and space. In particular, we observed a distal to proximal gradient in loop shape (length/width ratio) which varied over time, and a margin-to-center gradient in loop sizes. Quantitative analyses of vein patterns at the tissue level provide a two-way link between theoretical models of patterning and molecular experimental work to further explore patterning mechanisms during development. Such analyses could also be used to investigate the effect of environmental factors on vein patterns, or to compare venation patterns from different species for evolutionary studies. The method also provides a framework for gathering and overlaying two-dimensional maps of point, line and surface morphological data.

  12. Theory of two-dimensional ESR with nuclear modulation

    Science.gov (United States)

    Gamliel, Dan; Freed, Jack H.

    A formalism for computing 2D ESR lineshapes with nuclear modulation is developed in a form which is useful for planning phase cycles for particular purposes. A simple method of processing spectra, utilizing quadrature detection, is shown to enhance the selectivity of the phase cycling techniques. Computed ESR-COSY, ESR-SECSY, and 2D ELDOR lineshapes are presented for several kinds of polycrystalline and single-crystal samples which exhibit nuclear modulation, due to one or several nuclei. The two-dimensional methods are found to give more detailed structural information than the corresponding ESEEM spectra. New phase cycles are found to eliminate completely all transverse and axial peaks in 2D ELDOR and in ESR-COSY, and at the same time eliminate all artifacts arising from incomplete image rejection. Other phase cycles are presented for selecting in those experiments only axial peaks, for measuring T1. It is also shown how selective phase cycles may help to distinguish between coherent and exchange cross peaks. In the special case of nitroxides in typical Zeeman fields, there are no significant nuclear modulation effects from the 14N nuclear spin interaction, but those from the protons (or deuterons) will, in general, be significant.

  13. Flow of foams in two-dimensional disordered porous media

    Science.gov (United States)

    Dollet, Benjamin; Geraud, Baudouin; Jones, Sian A.; Meheust, Yves; Cantat, Isabelle; Institut de Physique de Rennes Team; Geosciences Rennes Team

    2015-11-01

    Liquid foams are a yield stress fluid with elastic properties. When a foam flow is confined by solid walls, viscous dissipation arises from the contact zones between soap films and walls, giving very peculiar friction laws. In particular, foams potentially invade narrow pores much more efficiently than Newtonian fluids, which is of great importance for enhanced oil recovery. To quantify this effect, we study experimentally flows of foam in a model two-dimensional porous medium, consisting of an assembly of circular obstacles placed randomly in a Hele-Shaw cell, and use image analysis to quantify foam flow at the local scale. We show that bubbles split as they flow through the porous medium, by a mechanism of film pinching during contact with an obstacle, yielding two daughter bubbles per split bubble. We quantify the evolution of the bubble size distribution as a function of the distance along the porous medium, the splitting probability as a function of bubble size, and the probability distribution function of the daughter bubbles. We propose an evolution equation to model this splitting phenomenon and compare it successfully to the experiments, showing how at long distance, the porous medium itself dictates the size distribution of the foam.

  14. Terahertz spectroscopy of two-dimensional subwavelength plasmonic structures

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul K [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Han, Jiaguang [OSU; Lu, Xinchao [OSU; Zhang, Weili [OSU

    2009-01-01

    The fascinating properties of plasmonic structures have had significant impact on the development of next generation ultracompact photonic and optoelectronic components. We study two-dimensional plasmonic structures functioning at terahertz frequencies. Resonant terahertz response due to surface plasmons and dipole localized surface plasmons were investigated by the state-of-the-art terahertz time domain spectroscopy (THz-TDS) using both transmission and reflection configurations. Extraordinary terahertz transmission was demonstrated through the subwavelength metallic hole arrays made from good conducting metals as well as poor metals. Metallic arrays m!lde from Pb, generally a poor metal, and having optically thin thicknesses less than one-third of a skin depth also contributed in enhanced THz transmission. A direct transition of a surface plasmon resonance from a photonic crystal minimum was observed in a photo-doped semiconductor array. Electrical controls of the surface plasmon resonances by hybridization of the Schottkey diode between the metallic grating and the semiconductor substrate are investigated as a function of the applied reverse bias. In addition, we have demonstrated photo-induced creation and annihilation of surface plasmons with appropriate semiconductors at room temperature. According to the Fano model, the transmission properties are characterized by two essential contributions: resonant excitation of surface plasmons and nonresonant direct transmission. Such plasmonic structures may find fascinating applications in terahertz imaging, biomedical sensing, subwavelength terahertz spectroscopy, tunable filters, and integrated terahertz devices.

  15. Aerodynamics of two-dimensional flapping wings in tandem configuration

    Science.gov (United States)

    Lua, K. B.; Lu, H.; Zhang, X. H.; Lim, T. T.; Yeo, K. S.

    2016-12-01

    This paper reports a fundamental investigation on the aerodynamics of two-dimensional flapping wings in tandem configuration in forward flight. Of particular interest are the effects of phase angle (φ) and center-to-center distance (L) between the front wing and the rear wing on the aerodynamic force generation at a Reynolds number of 5000. Both experimental and numerical methods were employed. A force sensor was used to measure the time-history aerodynamic forces experienced by the two wings and digital particle image velocimetry was utilized to obtain the corresponding flow structures. Both the front wing and the rear wing executed the same simple harmonic motions with φ ranging from -180° to 180° and four values of L, i.e., 1.5c, 2c, 3c, and 4c (c is the wing chord length). Results show that at fixed L = 2c, tandem wings perform better than the sum of two single wings that flap independently in terms of thrust for phase angle approximately from -90° to 90°. The maximum thrust on the rear wing occurs during in-phase flapping (φ = 0°). Correlation of transient thrust and flow structure indicates that there are generally two types of wing-wake interactions, depending on whether the rear wing crosses the shear layer shed from the front wing. Finally, increasing wing spacing has similar effect as reducing the phase angle, and an approximate mathematical model is derived to describe the relationship between these two parameters.

  16. 一种基于灰度级相位的指纹图像增强方法%Fingerprint Image Enhancement Approach Based on Gray-level Phase

    Institute of Scientific and Technical Information of China (English)

    佟喜峰; 刘雪梅; 李盼池; 韩玉祥; 尹晓喆; 肖红; 李鹏飞

    2012-01-01

    图像增强是指纹识别系统中非常重要的一个步骤.本文提出了灰度级相位的概念,并实现了一个根据灰度级相位增强指纹图像的方法.该方法首先计算指纹区域内每个像素点的灰度级相位,然后对灰度级相位进行滤波,最后根据滤波后的灰度级相位构建指纹图像.测试结果表明该方法对低质量的指纹图像增强效果好.%Image enhancement is an important procedure in an automatic fingerprint recognition system. An item called gray-level phase is defined, and a gray-level phase based image enhancement approach is proposed. In this approach, gray-level phase of each pixel is obtained firstly; then a filter is designed for gray-level phase; finally, the enhanced image is obtained according to the filtered gray-level phase. The experimental results show that the proposed approach is promising for low quality fingerprint image.

  17. Two Dimensional Spatial Independent Component Analysis and Its Application in fMRI Data Process

    Institute of Scientific and Technical Information of China (English)

    CHEN Hua-fu; YAO De-zhong

    2005-01-01

    One important application of independent component analysis (ICA) is in image processing. A two dimensional (2-D) composite ICA algorithm framework for 2-D image independent component analysis (2-D ICA) is proposed. The 2-D nature of the algorithm provides it an advantage of circumventing the roundabout transforming procedures between two dimensional (2-D) image data and one-dimensional (1-D) signal. Moreover the combination of the Newton (fixed-point algorithm) and natural gradient algorithms in this composite algorithm increases its efficiency and robustness. The convincing results of a successful example in functional magnetic resonance imaging (fMRI) show the potential application of composite 2-D ICA in the brain activity detection.

  18. Strategies for Ultrasound Imaging Using Two-Dimensional Arrays

    Science.gov (United States)

    Velichko, A.; Wilcox, P. D.

    2010-02-01

    2D arrays are able to `view' a given defect from a range of angles leading to the possibility of obtaining richer characterization detail than possible with 1D arrays. This has clear benefits as real defects and engineering structures are three-dimensional. This paper describes different approaches to optimize 2D array design. Results are shown that illustrate the application of the proposed techniques to modeling and experimental data.

  19. Real-Time Two-Dimensional Imaging of Microbubble Cavitation

    NARCIS (Netherlands)

    Vignon, F.; Shi, W.T.; Powers, J.E.; Liu, J.; Drvol, L.; Lof, J.; Everbach, C.; Gao, S.; Xie, F.; Porter, T.

    2011-01-01

    Ultrasound cavitation of microbubble contrast agents has a potentialfor therapeutic applications, including sonothrombolysis in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (e.g. stable versus inertial forms of cavitat

  20. A study of two-dimensional magnetic polaron

    Institute of Scientific and Technical Information of China (English)

    LIU; Tao; ZHANG; Huaihong; FENG; Mang; WANG; Kelin

    2006-01-01

    By using the variational method and anneal simulation, we study in this paper the self-trapped magnetic polaron (STMP) in two-dimensional anti-ferromagnetic material and the bound magnetic polaron (BMP) in ferromagnetic material. Schwinger angular momentum theory is applied to changing the problem into a coupling problem of carriers and two types of Bosons. Our calculation shows that there are single-peak and multi-peak structures in the two-dimensional STMP. For the ferromagnetic material, the properties of the two-dimensional BMP are almost the same as that in one-dimensional case; but for the anti-ferromagnetic material, the two-dimensional STMP structure is much richer than the one-dimensional case.

  1. UPWIND DISCONTINUOUS GALERKIN METHODS FOR TWO DIMENSIONAL NEUTRON TRANSPORT EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    袁光伟; 沈智军; 闫伟

    2003-01-01

    In this paper the upwind discontinuous Galerkin methods with triangle meshes for two dimensional neutron transport equations will be studied.The stability for both of the semi-discrete and full-discrete method will be proved.

  2. Two-Dimensionally-Modulated, Magnetic Structure of Neodymium Metal

    DEFF Research Database (Denmark)

    Lebech, Bente; Bak, P.

    1979-01-01

    The incipient magnetic order of dhcp Nd is described by a two-dimensional, incommensurably modulated structure ("triple-q" structure). The ordering is accompanied by a lattice distortion that forms a similar pattern....

  3. Entanglement Entropy for time dependent two dimensional holographic superconductor

    CERN Document Server

    Mazhari, N S; Myrzakulov, Kairat; Myrzakulov, R

    2016-01-01

    We studied entanglement entropy for a time dependent two dimensional holographic superconductor. We showed that the conserved charge of the system plays the role of the critical parameter to have condensation.

  4. Decoherence in a Landau Quantized Two Dimensional Electron Gas

    Directory of Open Access Journals (Sweden)

    McGill Stephen A.

    2013-03-01

    Full Text Available We have studied the dynamics of a high mobility two-dimensional electron gas as a function of temperature. The presence of satellite reflections in the sample and magnet can be modeled in the time-domain.

  5. Quantization of Two-Dimensional Gravity with Dynamical Torsion

    CERN Document Server

    Lavrov, P M

    1999-01-01

    We consider two-dimensional gravity with dynamical torsion in the Batalin - Vilkovisky and Batalin - Lavrov - Tyutin formalisms of gauge theories quantization as well as in the background field method.

  6. Spatiotemporal dissipative solitons in two-dimensional photonic lattices.

    Science.gov (United States)

    Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S

    2008-11-01

    We analyze spatiotemporal dissipative solitons in two-dimensional photonic lattices in the presence of gain and loss. In the framework of the continuous-discrete cubic-quintic Ginzburg-Landau model, we demonstrate the existence of novel classes of two-dimensional spatiotemporal dissipative lattice solitons, which also include surface solitons located in the corners or at the edges of the truncated two-dimensional photonic lattice. We find the domains of existence and stability of such spatiotemporal dissipative solitons in the relevant parameter space, for both on-site and intersite lattice solitons. We show that the on-site solitons are stable in the whole domain of their existence, whereas most of the intersite solitons are unstable. We describe the scenarios of the instability-induced dynamics of dissipative solitons in two-dimensional lattices.

  7. Bound states of two-dimensional relativistic harmonic oscillators

    Institute of Scientific and Technical Information of China (English)

    Qiang Wen-Chao

    2004-01-01

    We give the exact normalized bound state wavefunctions and energy expressions of the Klein-Gordon and Dirac equations with equal scalar and vector harmonic oscillator potentials in the two-dimensional space.

  8. A two-dimensional polymer prepared by organic synthesis.

    Science.gov (United States)

    Kissel, Patrick; Erni, Rolf; Schweizer, W Bernd; Rossell, Marta D; King, Benjamin T; Bauer, Thomas; Götzinger, Stephan; Schlüter, A Dieter; Sakamoto, Junji

    2012-02-05

    Synthetic polymers are widely used materials, as attested by a production of more than 200 millions of tons per year, and are typically composed of linear repeat units. They may also be branched or irregularly crosslinked. Here, we introduce a two-dimensional polymer with internal periodicity composed of areal repeat units. This is an extension of Staudinger's polymerization concept (to form macromolecules by covalently linking repeat units together), but in two dimensions. A well-known example of such a two-dimensional polymer is graphene, but its thermolytic synthesis precludes molecular design on demand. Here, we have rationally synthesized an ordered, non-equilibrium two-dimensional polymer far beyond molecular dimensions. The procedure includes the crystallization of a specifically designed photoreactive monomer into a layered structure, a photo-polymerization step within the crystal and a solvent-induced delamination step that isolates individual two-dimensional polymers as free-standing, monolayered molecular sheets.

  9. Second invariant for two-dimensional classical super systems

    Indian Academy of Sciences (India)

    S C Mishra; Roshan Lal; Veena Mishra

    2003-10-01

    Construction of superpotentials for two-dimensional classical super systems (for ≥ 2) is carried out. Some interesting potentials have been studied in their super form and also their integrability.

  10. Extreme paths in oriented two-dimensional percolation

    OpenAIRE

    Andjel, E. D.; Gray, L. F.

    2016-01-01

    International audience; A useful result about leftmost and rightmost paths in two dimensional bond percolation is proved. This result was introduced without proof in \\cite{G} in the context of the contact process in continuous time. As discussed here, it also holds for several related models, including the discrete time contact process and two dimensional site percolation. Among the consequences are a natural monotonicity in the probability of percolation between different sites and a somewha...

  11. Two Dimensional Nucleation Process by Monte Carlo Simulation

    OpenAIRE

    T., Irisawa; K., Matsumoto; Y., Arima; T., Kan; Computer Center, Gakushuin University; Department of Physics, Gakushuin University

    1997-01-01

    Two dimensional nucleation process on substrate is investigated by Monte Carlo simulation, and the critical nucleus size and its waiting time are measured with a high accuracy. In order to measure the critical nucleus with a high accuracy, we calculate the attachment and the detachment rate to the nucleus directly, and define the critical nucleus size when both rate are equal. Using the kinematical nucleation theory by Nishioka, it is found that, our obtained kinematical two dimensional criti...

  12. Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers

    Science.gov (United States)

    2016-06-15

    polymers . 2. Introduction . Research objectives: This research aims to study the physical (van der Waals forces: crystal epitaxy and π-π...AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY...Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4054 5c.  PROGRAM ELEMENT

  13. Two-Dimensional Weak Pseudomanifolds on Eight Vertices

    Indian Academy of Sciences (India)

    Basudeb Datta; Nandini Nilakantan

    2002-05-01

    We explicitly determine all the two-dimensional weak pseudomanifolds on 8 vertices. We prove that there are (up to isomorphism) exactly 95 such weak pseudomanifolds, 44 of which are combinatorial 2-manifolds. These 95 weak pseudomanifolds triangulate 16 topological spaces. As a consequence, we prove that there are exactly three 8-vertex two-dimensional orientable pseudomanifolds which allow degree three maps to the 4-vertex 2-sphere.

  14. Gray matter pathology and multiple sclerosis.

    Science.gov (United States)

    Wegner, Christiane; Stadelmann, Christine

    2009-09-01

    Gray matter demyelination is frequent and extensive in most patients with multiple sclerosis (MS) and has recently received much attention in neuropathologic and imaging studies. Gray matter lesions show distinct pathologic features that make their detection difficult with conventional imaging techniques. Thus, despite their high prevalence, their impact on clinical symptoms has not been defined well so far. This review focuses on recent information from pathologic and imaging studies and summarizes our current knowledge on cortical pathology derived from human and experimental studies.

  15. Two-dimensional optical tomography of hemodynamic changes in a preterm infant brain

    Science.gov (United States)

    Gao, Feng; Xue, Yuan; Zhao, Huijuan; Kusaka, Takashi; Ueno, Masanori; Yamada, Yukio

    2007-08-01

    Our preliminary results on two-dimensional (2D) optical tomographic imaging of hemodynamic changes in a preterm infant brain are reported. We use the established 16-channel time-correlated single photon counting system for the detection and generalized pulse spectrum technique based algorithm for the image reconstruction. The experiments demonstrate that diffuse optical tomography may be a potent means for investigating brain functions and neural development of infant brains in the perinatal period.

  16. Two-dimensional optical tomography of hemodynamic changes in a preterm infant brain

    Institute of Scientific and Technical Information of China (English)

    Feng Gao; Yuan Xue; Huijuan Zhao; Takashi Kusaka; Masanori Ueno; Yukio Yamada

    2007-01-01

    Our preliminary results on two-dimensional (2D) optical tomographic imaging of hemodynamic changes in a preterm infant brain are reported. We use the established 16-channel time-correlated single photon counting system for the detection and generalized pulse spectrum technique based algorithm for the image reconstruction. The experiments demonstrate that diffuse optical tomography may be a potent means for investigating brain functions and neural development of infant brains in the perinatal period.

  17. Two-dimensional graphene analogues for biomedical applications.

    Science.gov (United States)

    Chen, Yu; Tan, Chaoliang; Zhang, Hua; Wang, Lianzhou

    2015-05-07

    The increasing demand of clinical biomedicine and fast development of nanobiotechnology has substantially promoted the generation of a variety of organic/inorganic nanosystems for biomedical applications. Biocompatible two-dimensional (2D) graphene analogues (e.g., nanosheets of transition metal dichalcogenides, transition metal oxides, g-C3N4, Bi2Se3, BN, etc.), which are referred to as 2D-GAs, have emerged as a new unique family of nanomaterials that show unprecedented advantages and superior performances in biomedicine due to their unique compositional, structural and physicochemical features. In this review, we summarize the state-of-the-art progress of this dynamically developed material family with a particular focus on biomedical applications. After the introduction, the second section of the article summarizes a range of synthetic methods for new types of 2D-GAs as well as their surface functionalization. The subsequent section provides a snapshot on the use of these biocompatible 2D-GAs for a broad spectrum of biomedical applications, including therapeutic (photothermal/photodynamic therapy, chemotherapy and synergistic therapy), diagnostic (fluorescent/magnetic resonance/computed tomography/photoacoustic imaging) and theranostic (concurrent diagnostic imaging and therapy) applications, especially on oncology. In addition, we briefly present the biosensing applications of these 2D-GAs for the detection of biomacromolecules and their in vitro/in vivo biosafety evaluations. The last section summarizes some critical unresolved issues, possible challenges/obstacles and also proposes future perspectives related to the rational design and construction of 2D-GAs for biomedical engineering, which are believed to promote their clinical translations for benefiting the personalized medicine and human health.

  18. Two-Dimensional Materials for Sensing: Graphene and Beyond

    Directory of Open Access Journals (Sweden)

    Seba Sara Varghese

    2015-09-01

    Full Text Available Two-dimensional materials have attracted great scientific attention due to their unusual and fascinating properties for use in electronics, spintronics, photovoltaics, medicine, composites, etc. Graphene, transition metal dichalcogenides such as MoS2, phosphorene, etc., which belong to the family of two-dimensional materials, have shown great promise for gas sensing applications due to their high surface-to-volume ratio, low noise and sensitivity of electronic properties to the changes in the surroundings. Two-dimensional nanostructured semiconducting metal oxide based gas sensors have also been recognized as successful gas detection devices. This review aims to provide the latest advancements in the field of gas sensors based on various two-dimensional materials with the main focus on sensor performance metrics such as sensitivity, specificity, detection limit, response time, and reversibility. Both experimental and theoretical studies on the gas sensing properties of graphene and other two-dimensional materials beyond graphene are also discussed. The article concludes with the current challenges and future prospects for two-dimensional materials in gas sensor applications.

  19. Efficient processing of two-dimensional arrays with C or C++

    Science.gov (United States)

    Donato, David I.

    2017-07-20

    Because fast and efficient serial processing of raster-graphic images and other two-dimensional arrays is a requirement in land-change modeling and other applications, the effects of 10 factors on the runtimes for processing two-dimensional arrays with C and C++ are evaluated in a comparative factorial study. This study’s factors include the choice among three C or C++ source-code techniques for array processing; the choice of Microsoft Windows 7 or a Linux operating system; the choice of 4-byte or 8-byte array elements and indexes; and the choice of 32-bit or 64-bit memory addressing. This study demonstrates how programmer choices can reduce runtimes by 75 percent or more, even after compiler optimizations. Ten points of practical advice for faster processing of two-dimensional arrays are offered to C and C++ programmers. Further study and the development of a C and C++ software test suite are recommended.Key words: array processing, C, C++, compiler, computational speed, land-change modeling, raster-graphic image, two-dimensional array, software efficiency

  20. Assessment of left ventricular function by two-dimensional strain imaging in patients with different-stage chronic renal disease%二维应变技术对不同分期慢性肾脏病患者左室功能的评价

    Institute of Scientific and Technical Information of China (English)

    张丽; 林萍; 于妍洁; 赵久阳

    2012-01-01

    目的:探讨二维应变技术(2DS)评价不同分期慢性肾脏病患者左室收缩功能的价值.方法:100名慢性肾脏病患者按肾小球滤过率分为3组,A组(n=30)、B组(n=30)及C组(n=40),同时选取30名健康志愿者为正常对照组,分别取二维条件下心尖四腔切面、心尖两腔切面、心尖长轴切面3个连续心动周期图像.应用2DS获取左室18个节段心肌应变(s)及舒张早期应变率(SRe),并计算整体应变(GLS).结果:A组左室壁部分节段应变、应变率低于正常组.B组除间隔心尖段、下壁基底段、中间段以外,其余各节段收缩期应变均低于正常组,B组、C组各节段舒张早期应变率均低于正常组.其中,C组除前壁中间段、后壁心尖段以外,其他节段均较A组降低.B组、C组整体应变低于正常.结论:二维应变技术可以早期发现慢性肾脏病患者左室心肌收缩及舒张功能的异常.%AIM: To evaluate the application of two-dimensional strain imaging (2DS) in assessing the left ventricular function in patients with chronic renal diseases. METHODS: One hundred patients with chronic renal diseases were divided into three groups: group A (n=30) , group B (n=30) and group C (n=40) according to the severity of the renal disease and underwent 2DS. Thirty two healthy subjects were recruited as control group. Four-chamber apical views, two-chamber apical views and left ventricular long-axis views of two-dimensional images were stored. Longitudinal strain (S) and early diastolic strain rate (SRe) of left ventricular segments were obtained by 2DS software. RESULTS; Compared with those in the control group, the S and SRe in some segments in group A decreased and except for the S of the apical anteroseptum and the basal and middle segments of inferior wall, the S and SRe of each wall of left ventricle in group B also decreased. The S and SRe of all segments in group C significantly decreased compared with those in the control group. Except

  1. Quantitative evaluation of left ventricular function in isolated ventricular noncompaction patients by two-dimensional strain imaging%二维应变成像定量评价孤立性心肌致密化不全患者左心室功能

    Institute of Scientific and Technical Information of China (English)

    张晓红; 朱文晖; 赵永峰

    2011-01-01

    目的 探讨应用二维应变成像技术定量评价孤立性心肌致密化不全患者(IVNC)左心室收缩功能改变的价值.方法 IVNC患者14例(IVNC组)和正常对照组20例,行常规超声心动图检查及二维应变成像,比较两组之间各节段收缩期峰值应变的差异,分析致密化不全节段致密化不全内层与致密化外层厚度的比值(NC/C),及其与收缩期峰值应变的关系.结果 IVNC组左室各节段收缩期峰值应变绝对值较正常对照组显著下降(P<0.05),其中侧壁、后壁、下壁各节段及心尖部各节段收缩期峰值应变绝对值下降程度更显著(P<0.01).致密化不全心肌节段NC/C值与其收缩期峰值应变密切相关(r=0.86,P<0.01).结论 二维应变成像可以定量评价心肌致密化不全患者左心室各节段收缩功能改变,致密化不全节段室壁收缩功能下降与其致密化程度密切相关.%Objective To quantitatively evaluate the left ventricular systolic function in isolated ventricular noncompaction( IVNC ) patients by two - dimensional strain imaging. Methods IVNC group( n = 14 ) and normal group( n =20 ) were examined by conventional echocardiography and two - dimensional strain imaging. Defferences in segmental peak systolic strain between two groups were compared, the relationship between the ratio of non - compacted to compacted myocardium( NC/C ratio ) and peak systolic strain in all noncompacted segments was analyzed. Results Compared with normal group, the peak systolic strain in IVNC group was significantly decreased in all left ventricular segments( P < 0. 05 ), especially in lateral wall, posterior wall, inferior wall and apex segments( P < 0. 01 ). NC/C ratio in noncompacted segments was correlated with peak systolic strain( r = 0. 86 , P < 0. 01 ). Conclusion Two - dimensional strain imaging can quantitatively evaluate left ventricular systolic function of IVNC patients. The extent of myocardial noncompaction is associated

  2. Application of two-dimensional ultrasound imaging in the evaluation of left entricular function of patients with acute myocardial infarction%二维超声成像在急性心肌梗死患者左室功能评估中的应用

    Institute of Scientific and Technical Information of China (English)

    胡桂珍; 肖永芳

    2012-01-01

    Objective To study the changes of two-dimensional ultrasound imaging in the evaluation of left entricular function of patients with acute myocardial infarction. Methods The clinical data of 40 patients with acute myocardial infarction in our hospital from October 2009 to May 2011 were analyzed retrospectively. All patients were divided into two groups, anterior wall myocardial infarction group (20 cases) and inferior myocardial infarction group (20 cases) according to different parts of obstruction. Each segment of circumferential strain of patients with left ventricular myocardial infarction of the two groups was detected by two-dimensional ultrasound spots tracking imaging (STI). Results In the conventional ultrasound examination, the LVDD, LVDS of anterior wall myocardial infarction group were significantly greater than the inferior myocardial infarction group, LVEF was obviously less than the inferior myocardial infarction group. Each segment of circumferential strain of anterior wall, interventricular septum and cardiac apex in the anterior wall myocardial infarction group was significantly less than the inferior myocardial infarction group, while each segment of circumferential strain of posterior wall and inferior wall was less than the inferior myocardial infarction group (P < 0.05); and GCS of the anterior wall myocardial infarction group was less than the inferior myocardial infarction group (P < 0.01). Conclusion The two-dimensional ultrasound imaging can quantitative evaluate the changes of left ventricular function of patients with acute myocardial infarction, and provide an effective, non-inasie method for evaluating the changes of left ventricular function in clinic.%目的 探讨二维超声成像在评估急性心肌梗死患者左室功能变化情况.方法 回顾性分析我院2009年10月~2011年5月收治入院的40例急性心梗患者临床资料,根据梗阻部位不同分为两组,前壁心梗组(20例)和下壁心梗组(20例),两组

  3. Improved delineation of short cortical association fibers and gray/white matter boundary using whole-brain three-dimensional diffusion tensor imaging at submillimeter spatial resolution.

    Science.gov (United States)

    Song, Allen W; Chang, Hing-Chiu; Petty, Christopher; Guidon, Arnaud; Chen, Nan-Kuei

    2014-11-01

    Recent emergence of human connectome imaging has led to a high demand on angular and spatial resolutions for diffusion magnetic resonance imaging (MRI). While there have been significant growths in high angular resolution diffusion imaging, the improvement in spatial resolution is still limited due to a number of technical challenges, such as the low signal-to-noise ratio and high motion artifacts. As a result, the benefit of a high spatial resolution in the whole-brain connectome imaging has not been fully evaluated in vivo. In this brief report, the impact of spatial resolution was assessed in a newly acquired whole-brain three-dimensional diffusion tensor imaging data set with an isotropic spatial resolution of 0.85 mm. It was found that the delineation of short cortical association fibers is drastically improved as well as the definition of fiber pathway endings into the gray/white matter boundary-both of which will help construct a more accurate structural map of the human brain connectome.

  4. 基于侧抑制网络的二维Otsu阈值分割算法%Two-dimensional Otsu Threshold Segmentation Algorithm Based on Lateral Inhibition Network

    Institute of Scientific and Technical Information of China (English)

    董悫; 王江晴; 孙阳光

    2015-01-01

    The traditional two-dimensional Otsu thresholding segmentation algorithms do not think about human vision characteristics and the result of segmentation can not match up to the visual perception of human eye. In order to solve this problem,an algorithm based on the two-dimensional Otsu algorithm and the lateral inhibition network is proposed. In this algorithm, the lateral inhibition network of human visual system that has the features of enhancing center and inhibiting surroundings is fully used. The lateral inhibition network is utilized to process the original picture and obtains the lateral inhibition picture. A two-dimensional histogram based on the gray information and lateral inhibition information of pixels is established. The maximum between-cluster variance is chosen as the criterion to select the optimal threshold. Experimental results show that this algorithm not only is well adapted to the contrast and illumination intensity, but also has the capacity for fitting the breaks compared with the traditional Otsu algorithm and two-dimensional Otsu algorithm. It improves the robustness to image noise and obtains more perfect segmentation results.%传统二维Otsu阈值分割算法未考虑人类视觉特性,分割结果不符合人眼视觉感受。为此,提出一种二维Otsu算法与侧抑制网络相结合的分割算法。该算法从基于人类视觉系统的侧抑制网络出发,利用侧抑制网络增强中心,抑制周围的特性,通过侧抑制网络处理原始图像,得到侧抑制图像,构建基于像素的灰度信息和侧抑制信息的二维直方图,并采用类间最大方差作为最佳阈值的选取准则。实验结果表明,与传统的Otsu算法和二维Otsu算法等相比,该算法具有较好的对比度、光照强度适应性和间断拟合能力,并能提高对图像噪声的鲁棒性,获得更理想的分割结果。

  5. Premature graying of hair

    National Research Council Canada - National Science Library

    Pandhi, Deepika; Khanna, Deepshikha

    2013-01-01

    .... It needs to be differentiated from various genetic hypomelanotic hair disorders. Reduction in melanogenically active melanocytes in the hair bulb of gray anagen hair follicles with resultant pigment loss is central to the pathogenesis of graying...

  6. 二维应变成像评价双胎输血综合征受血儿右心功能的初步研究%Assessment of right ventricular function in recipient fetus of twin-twin transfusion syndrome with two-dimensional strain imaging

    Institute of Scientific and Technical Information of China (English)

    赵胜; 邓又斌; 陈欣林; 刘蓉

    2011-01-01

    Objective To evaluate the value of two-dimensional strain imaging in assessing right ventricular function of recipient fetus in TTTS pregnancies.Methods Sixteen TTTS pregnancies and 19 normal monochorionic diamniotic pregnancies(controls) were included.Doppler studies of the umbilical artery,umbilical vein,ductus venosus,middle cerebral artery,atrioventricular valve and semilunar value were recorded in both fetus,and myocardial performance index of both ventricles was calculated.Longitudinal peak systolic strain of right ventricular were calculated and compared between recipient fetus and other fetus.Results Cardiothoracic ratio and myocardial performance index of right ventricular showed significant differences between recipient fetus and controls.Right ventricular strain was decreased in recipient fetus compared with controls.Conclusions Two-dimensional strain imaging can be used to evaluate right ventricular myocardial function in the recipient fetus of TTTS.%目的 探讨二维应变成像在评价双胎输血综合征(twin-twin transfusion syndrome,TTTS)受血儿右心功能中的价值.方法 选择TTTS 16例及正常单绒毛膜囊双羊膜囊双胎19例,分别测量两个胎儿脐动脉、脐静脉、静脉导管、大脑中动脉、房室瓣口、半月瓣口等部位的血流频谱参数,计算心肌做功指数.然后局部放大胎儿四腔心,清晰显示心内膜及肌层,动态存储2~3个心动周期,脱机分析两组胎儿右心纵向收缩期峰值应变.结果 TTTS受血儿心胸面积比值、右心心肌做功指数大于供血儿及对照组,差异有统计学意义;TTTS受血儿右心游离壁、室间隔及平均纵向收缩期峰值应变小于供血儿及对照组,差异有统计学意义.结论 二维应变成像可反映TTTS受血儿的右心心肌运动异常,但是在羊水过多及胎动频繁时应用受到限制.

  7. 超声斑点追踪显像技术评价缩窄性心包炎患者左心室局部心肌收缩功能%Evaluation of regional myocardial systolic function of left ventricular in patients with constrictive pericarditis by two-dimensional speckle-tracking imaging

    Institute of Scientific and Technical Information of China (English)

    熊芸; 谢明星; 方凌云; 郑少萍

    2011-01-01

    Objective To evaluate regional myocardial systolic function of left ventricular in patients with constrictive pericarditis(CP)by two-dimensional speckle-tracking imaging(STI).Methods Study population consisted of 26 patients with CP and 37 normal control subjects.High frame rate two-dimensional images were recorded from the apical four-chamber view ,two-chamber view and long -axis view of the left ventricle respectively.The peak systolic longitudinal strain of the left ventricle free wall was measured using 2D strain software ,and the indexes were compared between the two groups.Results The epi-strain in patients with CP was significantly decrased ,compared with those in the control group(P>0.05).No significant difference in the endo -strain was found between the control group and CP group.Conclusions STI could objectively evaluate the regional myocardial systolic function of left ventricular in patients with CP.The epi-strain in the left ventricle free wall has decreased in patients with CP,which means the epi-myocardial systolic properties of left vebtricular are impaired in CP patients.%目的 应用超声斑点追踪显像技术(STI)评价缩窄性心包炎(CP)患者左心室局部心肌收缩功能.方法 采集26例CP患者左心室心尖位四腔切面、两腔切面、左心室长轴高帧频图像,测量左心室游离壁(前侧壁、下侧壁、前壁、下壁)心内、外膜下心肌各个节段的二维纵向收缩期应变峰值,并与37例正常人比较.结果 (1)CP患者左心室游离壁心外膜下心肌各节段纵向收缩期应变峰值较对照组明显减低(P0.05).结论 超声二维应变成像技术能够准确地定量评价CP患者左心室游离壁心内膜下及心外膜下心肌收缩功能,CP患者左心室游离壁心外膜下心肌纵向收缩期峰值应变减低,提示心外膜下心肌收缩功能受损.

  8. SUPER-RESOLUTION AND DE-CONVOLUTION FOR SINGLE/MULTI GRAY SCALE IMAGES USING SIFT ALGORITHM

    Directory of Open Access Journals (Sweden)

    Ritu Soni

    2015-10-01

    Full Text Available This paper represent a Blind algorithm that restore the blurred images for single image and multi-image blur de-convolution and multi-image super-resolution on low-resolution images deteriorated by additive white Gaussian noise ,the aliasing and linear space-invariant. Image De-blurring is a field of Image Processing in which recovering an original and sharp image from a corrupted image. Proposed method is based on alternating minimization algorithm with respect to unidentified blurs and high-resolution image and the Huber-markov random field(HMRF model for its ability to preserve discontinuities of a image and used for the regularization that exploits the piecewise smooth nature of the HR image. SIFT algorithm is used for feature extraction in a image and produce matching features based on Euclidean distance of their feature vectors that help in calculation of PSF. For blur estimation, edge-emphasizing smoothing operation is used to improve the quality of blur by enhancing the strong soft edges. In filter domain the blur estimation process can be done rather than the pixel domain for better performance that means which uses the gradient of HR and LR images for better performance.

  9. Multivariate imaging-genetics study of MRI gray matter volume and SNPs reveals biological pathways correlated with brain structural differences in Attention Deficit Hyperactivity Disorder

    Directory of Open Access Journals (Sweden)

    Sabin Khadka

    2016-07-01

    Full Text Available Background: Attention Deficit Hyperactivity Disorder (ADHD is a prevalent neurodevelopmental disorder affecting children, adolescents, and adults. Its etiology is not well-understood, but it is increasingly believed to result from diverse pathophysiologies that affect the structure and function of specific brain circuits. Although one of the best-studied neurobiological abnormalities in ADHD is reduced fronto-striatal-cerebellar gray matter volume, its specific genetic correlates are largely unknown. Methods: In this study, T1-weighted MR images of brain structure were collected from 198 adolescents (63 ADHD-diagnosed. A multivariate parallel independent component analysis technique (Para-ICA identified imaging-genetic relationships between regional gray matter volume and single nucleotide polymorphism data. Results: Para-ICA analyses extracted 14 components from genetic data and 9 from MR data. An iterative cross-validation using randomly-chosen sub-samples indicated acceptable stability of these ICA solutions. A series of partial correlation analyses controlling for age, sex, and ethnicity revealed two genotype-phenotype component pairs significantly differed between ADHD and non-ADHD groups, after a Bonferroni correction for multiple comparisons. The brain phenotype component not only included structures frequently found to have abnormally low volume in previous ADHD studies, but was also significantly associated with ADHD differences in symptom severity and performance on cognitive tests frequently found to be impaired in patients diagnosed with the disorder. Pathway analysis of the genotype component identified several different biological pathways linked to these structural abnormalities in ADHD. Conclusions: Some of these pathways implicate well-known dopaminergic neurotransmission and neurodevelopment hypothesized to be abnormal in ADHD. Other more recently implicated pathways included glutamatergic and GABA-eric physiological systems

  10. Tracking dynamics of two-dimensional continuous attractor neural networks

    Science.gov (United States)

    Fung, C. C. Alan; Wong, K. Y. Michael; Wu, Si

    2009-12-01

    We introduce an analytically solvable model of two-dimensional continuous attractor neural networks (CANNs). The synaptic input and the neuronal response form Gaussian bumps in the absence of external stimuli, and enable the network to track external stimuli by its translational displacement in the two-dimensional space. Basis functions of the two-dimensional quantum harmonic oscillator in polar coordinates are introduced to describe the distortion modes of the Gaussian bump. The perturbative method is applied to analyze its dynamics. Testing the method by considering the network behavior when the external stimulus abruptly changes its position, we obtain results of the reaction time and the amplitudes of various distortion modes, with excellent agreement with simulation results.

  11. Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

    Science.gov (United States)

    Wang, Qing Hua; Kalantar-Zadeh, Kourosh; Kis, Andras; Coleman, Jonathan N; Strano, Michael S

    2012-11-01

    The remarkable properties of graphene have renewed interest in inorganic, two-dimensional materials with unique electronic and optical attributes. Transition metal dichalcogenides (TMDCs) are layered materials with strong in-plane bonding and weak out-of-plane interactions enabling exfoliation into two-dimensional layers of single unit cell thickness. Although TMDCs have been studied for decades, recent advances in nanoscale materials characterization and device fabrication have opened up new opportunities for two-dimensional layers of thin TMDCs in nanoelectronics and optoelectronics. TMDCs such as MoS(2), MoSe(2), WS(2) and WSe(2) have sizable bandgaps that change from indirect to direct in single layers, allowing applications such as transistors, photodetectors and electroluminescent devices. We review the historical development of TMDCs, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.

  12. Hamiltonian formalism of two-dimensional Vlasov kinetic equation.

    Science.gov (United States)

    Pavlov, Maxim V

    2014-12-08

    In this paper, the two-dimensional Benney system describing long wave propagation of a finite depth fluid motion and the multi-dimensional Russo-Smereka kinetic equation describing a bubbly flow are considered. The Hamiltonian approach established by J. Gibbons for the one-dimensional Vlasov kinetic equation is extended to a multi-dimensional case. A local Hamiltonian structure associated with the hydrodynamic lattice of moments derived by D. J. Benney is constructed. A relationship between this hydrodynamic lattice of moments and the two-dimensional Vlasov kinetic equation is found. In the two-dimensional case, a Hamiltonian hydrodynamic lattice for the Russo-Smereka kinetic model is constructed. Simple hydrodynamic reductions are presented.

  13. Control Operator for the Two-Dimensional Energized Wave Equation

    Directory of Open Access Journals (Sweden)

    Sunday Augustus REJU

    2006-07-01

    Full Text Available This paper studies the analytical model for the construction of the two-dimensional Energized wave equation. The control operator is given in term of space and time t independent variables. The integral quadratic objective cost functional is subject to the constraint of two-dimensional Energized diffusion, Heat and a source. The operator that shall be obtained extends the Conjugate Gradient method (ECGM as developed by Hestenes et al (1952, [1]. The new operator enables the computation of the penalty cost, optimal controls and state trajectories of the two-dimensional energized wave equation when apply to the Conjugate Gradient methods in (Waziri & Reju, LEJPT & LJS, Issues 9, 2006, [2-4] to appear in this series.

  14. Two-Dimensional Electronic Spectroscopy Using Incoherent Light: Theoretical Analysis

    CERN Document Server

    Turner, Daniel B; Sutor, Erika J; Hendrickson, Rebecca A; Gealy, M W; Ulness, Darin J

    2012-01-01

    Electronic energy transfer in photosynthesis occurs over a range of time scales and under a variety of intermolecular coupling conditions. Recent work has shown that electronic coupling between chromophores can lead to coherent oscillations in two-dimensional electronic spectroscopy measurements of pigment-protein complexes measured with femtosecond laser pulses. A persistent issue in the field is to reconcile the results of measurements performed using femtosecond laser pulses with physiological illumination conditions. Noisy-light spectroscopy can begin to address this question. In this work we present the theoretical analysis of incoherent two-dimensional electronic spectroscopy, I(4) 2D ES. Simulations reveal diagonal peaks, cross peaks, and coherent oscillations similar to those observed in femtosecond two-dimensional electronic spectroscopy experiments. The results also expose fundamental differences between the femtosecond-pulse and noisy-light techniques; the differences lead to new challenges and opp...

  15. A two-dimensional spin liquid in quantum kagome ice.

    Science.gov (United States)

    Carrasquilla, Juan; Hao, Zhihao; Melko, Roger G

    2015-06-22

    Actively sought since the turn of the century, two-dimensional quantum spin liquids (QSLs) are exotic phases of matter where magnetic moments remain disordered even at zero temperature. Despite ongoing searches, QSLs remain elusive, due to a lack of concrete knowledge of the microscopic mechanisms that inhibit magnetic order in materials. Here we study a model for a broad class of frustrated magnetic rare-earth pyrochlore materials called quantum spin ices. When subject to an external magnetic field along the [111] crystallographic direction, the resulting interactions contain a mix of geometric frustration and quantum fluctuations in decoupled two-dimensional kagome planes. Using quantum Monte Carlo simulations, we identify a set of interactions sufficient to promote a groundstate with no magnetic long-range order, and a gap to excitations, consistent with a Z2 spin liquid phase. This suggests an experimental procedure to search for two-dimensional QSLs within a class of pyrochlore quantum spin ice materials.

  16. Spectral Radiative Properties of Two-Dimensional Rough Surfaces

    Science.gov (United States)

    Xuan, Yimin; Han, Yuge; Zhou, Yue

    2012-12-01

    Spectral radiative properties of two-dimensional rough surfaces are important for both academic research and practical applications. Besides material properties, surface structures have impact on the spectral radiative properties of rough surfaces. Based on the finite difference time domain algorithm, this paper studies the spectral energy propagation process on a two-dimensional rough surface and analyzes the effect of different factors such as the surface structure, angle, and polarization state of the incident wave on the spectral radiative properties of the two-dimensional rough surface. To quantitatively investigate the spatial distribution of energy reflected from the rough surface, the concept of the bidirectional reflectance distribution function is introduced. Correlation analysis between the reflectance and different impact factors is conducted to evaluate the influence degree. Comparison between the theoretical and experimental data is given to elucidate the accuracy of the computational code. This study is beneficial to optimizing the surface structures of optoelectronic devices such as solar cells.

  17. Optical modulators with two-dimensional layered materials

    CERN Document Server

    Sun, Zhipei; Wang, Feng

    2016-01-01

    Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that two-dimensional layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this review, we cover the state-of-the-art of optical modulators based on two-dimensional layered materials including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as two-dimensional heterostructures, plasmonic structures, and silicon/fibre integrated structures. We also take a look at future perspectives and discuss the potential of yet relatively unexplored mechanisms such as magneto-optic and acousto-optic modulation.

  18. Two-dimensional superconductors with atomic-scale thickness

    Science.gov (United States)

    Uchihashi, Takashi

    2017-01-01

    Recent progress in two-dimensional superconductors with atomic-scale thickness is reviewed mainly from the experimental point of view. The superconducting systems treated here involve a variety of materials and forms: elemental metal ultrathin films and atomic layers on semiconductor surfaces; interfaces and superlattices of heterostructures made of cuprates, perovskite oxides, and rare-earth metal heavy-fermion compounds; interfaces of electric-double-layer transistors; graphene and atomic sheets of transition metal dichalcogenide; iron selenide and organic conductors on oxide and metal surfaces, respectively. Unique phenomena arising from the ultimate two dimensionality of the system and the physics behind them are discussed.

  19. TreePM Method for Two-Dimensional Cosmological Simulations

    Indian Academy of Sciences (India)

    Suryadeep Ray

    2004-09-01

    We describe the two-dimensional TreePM method in this paper. The 2d TreePM code is an accurate and efficient technique to carry out large two-dimensional N-body simulations in cosmology. This hybrid code combines the 2d Barnes and Hut Tree method and the 2d Particle–Mesh method. We describe the splitting of force between the PM and the Tree parts. We also estimate error in force for a realistic configuration. Finally, we discuss some tests of the code.

  20. Singular analysis of two-dimensional bifurcation system

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Bifurcation properties of two-dimensional bifurcation system are studied in this paper.Universal unfolding and transition sets of the bifurcation equations are obtained.The whole parametric plane is divided into several different persistent regions according to the type of motion,and the different qualitative bifurcation diagrams in different persistent regions are given.The bifurcation properties of the two-dimensional bifurcation system are compared with its reduced one-dimensional system.It is found that the system which is reduced to one dimension has lost many bifurcation properties.