WorldWideScience

Sample records for geometry-driven optical flow

  1. Geometry-Driven Polarity in Motile Amoeboid Cells.

    Directory of Open Access Journals (Sweden)

    Oliver Nagel

    Full Text Available Motile eukaryotic cells, such as leukocytes, cancer cells, and amoeba, typically move inside the narrow interstitial spacings of tissue or soil. While most of our knowledge of actin-driven eukaryotic motility was obtained from cells that move on planar open surfaces, recent work has demonstrated that confinement can lead to strongly altered motile behavior. Here, we report experimental evidence that motile amoeboid cells undergo a spontaneous symmetry breaking in confined interstitial spaces. Inside narrow channels, the cells switch to a highly persistent, unidirectional mode of motion, moving at a constant speed along the channel. They remain in contact with the two opposing channel side walls and alternate protrusions of their leading edge near each wall. Their actin cytoskeleton exhibits a characteristic arrangement that is dominated by dense, stationary actin foci at the side walls, in conjunction with less dense dynamic regions at the leading edge. Our experimental findings can be explained based on an excitable network model that accounts for the confinement-induced symmetry breaking and correctly recovers the spatio-temporal pattern of protrusions at the leading edge. Since motile cells typically live in the narrow interstitial spacings of tissue or soil, we expect that the geometry-driven polarity we report here plays an important role for movement of cells in their natural environment.

  2. Robust Optical Flow Estimation

    Directory of Open Access Journals (Sweden)

    Javier Sánchez Pérez

    2013-10-01

    Full Text Available n this work, we describe an implementation of the variational method proposed by Brox etal. in 2004, which yields accurate optical flows with low running times. It has several benefitswith respect to the method of Horn and Schunck: it is more robust to the presence of outliers,produces piecewise-smooth flow fields and can cope with constant brightness changes. Thismethod relies on the brightness and gradient constancy assumptions, using the information ofthe image intensities and the image gradients to find correspondences. It also generalizes theuse of continuous L1 functionals, which help mitigate the effect of outliers and create a TotalVariation (TV regularization. Additionally, it introduces a simple temporal regularizationscheme that enforces a continuous temporal coherence of the flow fields.

  3. Optic flow and autonomous navigation.

    Science.gov (United States)

    Campani, M; Giachetti, A; Torre, V

    1995-01-01

    Many animals, especially insects, compute and use optic flow to control their motion direction and to avoid obstacles. Recent advances in computer vision have shown that an adequate optic flow can be computed from image sequences. Therefore studying whether artificial systems, such as robots, can use optic flow for similar purposes is of particular interest. Experiments are reviewed that suggest the possible use of optic flow for the navigation of a robot moving in indoor and outdoor environments. The optic flow is used to detect and localise obstacles in indoor scenes, such as corridors, offices, and laboratories. These routines are based on the computation of a reduced optic flow. The robot is usually able to avoid large obstacles such as a chair or a person. The avoidance performances of the proposed algorithm critically depend on the optomotor reaction of the robot. The optic flow can be used to understand the ego-motion in outdoor scenes, that is, to obtain information on the absolute velocity of the moving vehicle and to detect the presence of other moving objects. A critical step is the correction of the optic flow for shocks and vibrations present during image acquisition. The results obtained suggest that optic flow can be successfully used by biological and artificial systems to control their navigation. Moreover, both systems require fast and accurate optomotor reactions and need to compensate for the instability of the viewed world.

  4. Optical diagnostics of intermittent flows

    DEFF Research Database (Denmark)

    Okulov, V.L.; Naumov, I.V.; Sørensen, Jens Nørkær

    2007-01-01

    The efficiency of combined use of different optical techniques for flow diagnostics is demonstrated with the practically important case of intense swirling flows. It is shown that, when applied separately, commonly used optical measuring techniques, such as laser Doppler anemometry and particle...... image velocimetry, frequently give erroneous results, especially for the transition flow and developed nonstationary flow. However, their combined use in diagnostics of unsteady (intermittent) flows significantly improves both the temporal and spatial resolution of measurements. Such a complex approach...... is for the first time applied for diagnostics of the flow pattern in a closed cylinder with a rotating end face with the aim of studying the changeover from the steady axisymmetric to unsteady asymmetric flow over a wide range of flow parameters. It is found that such a transition is notable for azimuthal...

  5. A ROBUST OPTICAL FLOW COMPUTATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a new method for robust and accurate optical flow estimation. The significance of this work is twofold. Firstly, the idea of bi-directional scheme is adopted to reduce the model error of optical flow equation, which allows the second order Taylor's expansion of optical flow equation for accurate solution without much extra computational burden; Secondly, this paper establishs a new optical flow equation based on LSCM (Local Structure Constancy Model) instead of BCM (Brightness Constancy Model), namely the optical flow equation does not act on scalar but on tensor-valued (matrix-valued) field, due to the two reason: (1) structure tensor-value contains local spatial structure information, which provides us more useable cues for computation than scalar; (2) local image structure is less sensitive to illumination variation than intensity, which weakens the disturbance of non-uniform illumination in real sequences. Qualitative and quantitative results for synthetic and real-world scenes show that the new method can produce an accurate and robust results.

  6. Insect vision: controlling actions through optic flow.

    Science.gov (United States)

    Collett, Thomas S

    2002-09-17

    Insects depend upon optic flow to supply much of their information about the three-dimensional structure of the world. Many insects use translational flow to measure the distance of objects from themselves. A recent study has provided new insights into the way Drosophila use optic flow to pick out a close target to approach.

  7. Finding Elephant Flows for Optical Networks

    NARCIS (Netherlands)

    Fioreze, Tiago; Oude Wolbers, Mattijs; Meent, van de Remco; Pras, Aiko

    2007-01-01

    Optical networks are fast and reliable networks that enable, amongst others, dedicated light paths to be established for elephant IP flows. Elephant IP flows are characterized by being small in number, but long in time and high in traffic volume. Moving these flows from the general IP network to ded

  8. On a Decomposition Model for Optical Flow

    Science.gov (United States)

    Abhau, Jochen; Belhachmi, Zakaria; Scherzer, Otmar

    In this paper we present a variational method for determining cartoon and texture components of the optical flow of a noisy image sequence. The method is realized by reformulating the optical flow problem first as a variational denoising problem for multi-channel data and then by applying decomposition methods. Thanks to the general formulation, several norms can be used for the decomposition. We study a decomposition for the optical flow into bounded variation and oscillating component in greater detail. Numerical examples demonstrate the capabilities of the proposed approach.

  9. Duality based optical flow algorithms with applications

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau

    We consider the popular TV-L1 optical flow formulation, and the so-called duality based algorithm for minimizing the TV-L1 energy. The original formulation is extended to allow for vector valued images, and minimization results are given. In addition we consider different definitions of total...... variation regularization, and related formulations of the optical flow problem that may be used with a duality based algorithm. We present a highly optimized algorithmic setup to estimate optical flows, and give five novel applications. The first application is registration of medical images, where X......-ray images of different hands, taken using different imaging devices are registered using a TV-L1 optical flow algorithm. We propose to regularize the input images, using sparsity enhancing regularization of the image gradient to improve registration results. The second application is registration of 2D...

  10. Duality based optical flow algorithms with applications

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau

    We consider the popular TV-L1 optical flow formulation, and the so-called duality based algorithm for minimizing the TV-L1 energy. The original formulation is extended to allow for vector valued images, and minimization results are given. In addition we consider different definitions of total...... variation regularization, and related formulations of the optical flow problem that may be used with a duality based algorithm. We present a highly optimized algorithmic setup to estimate optical flows, and give five novel applications. The first application is registration of medical images, where X......-ray images of different hands, taken using different imaging devices are registered using a TV-L1 optical flow algorithm. We propose to regularize the input images, using sparsity enhancing regularization of the image gradient to improve registration results. The second application is registration of 2D...

  11. Flow line asymmetric nonimaging concentrating optics

    Science.gov (United States)

    Jiang, Lun; Winston, Roland

    2016-09-01

    Nonimaging Optics has shown that it achieves the theoretical limits by utilizing thermodynamic principles rather than conventional optics. Hence in this paper the condition of the "best" design are both defined and fulfilled in the framework of thermodynamic arguments, which we believe has profound consequences for the designs of thermal and even photovoltaic systems, even illumination and optical communication tasks. This new way of looking at the problem of efficient concentration depends on probabilities, geometric flux field and radiative heat transfer while "optics" in the conventional sense recedes into the background. Some of the new development of flow line designs will be introduced and the connection between the thermodynamics and flow line design will be officially formulated in the framework of geometric flux field. A new way of using geometric flux to design nonimaging optics will be introduced. And finally, we discuss the possibility of 3D ideal nonimaing optics.

  12. Distributed flow sensing using optical hot -wire grid.

    Science.gov (United States)

    Chen, Tong; Wang, Qingqing; Zhang, Botao; Chen, Rongzhang; Chen, Kevin P

    2012-04-09

    An optical hot-wire flow sensing grid is presented using a single piece of self-heated optical fiber to perform distributed flow measurement. The flow-induced temperature loss profiles along the fiber are interrogated by the in-fiber Rayleigh backscattering, and spatially resolved in millimeter resolution using optical frequency domain reflectometry (OFDR). The flow rate, position, and flow direction are retrieved simultaneously. Both electrical and optical on-fiber heating were demonstrated to suit different flow sensing applications.

  13. Optical Flow based Robot Obstacle Avoidance

    Directory of Open Access Journals (Sweden)

    Kahlouche Souhila

    2008-11-01

    Full Text Available In this paper we try to develop an algorithm for visual obstacle avoidance of autonomous mobile robot. The input of the algorithm is an image sequence grabbed by an embedded camera on the B21r robot in motion. Then, the optical flow information is extracted from the image sequence in order to be used in the navigation algorithm. The optical flow provides very important information about the robot environment, like: the obstacles disposition, the robot heading, the time to collision and the depth. The strategy consists in balancing the amount of left and right side flow to avoid obstacles, this technique allows robot navigation without any collision with obstacles. The robustness of the algorithm will be showed by some examples.

  14. Variational optical flow computation in real time.

    Science.gov (United States)

    Bruhn, Andrés; Weickert, Joachim; Feddern, Christian; Kohlberger, Timo; Schnörr, Christoph

    2005-05-01

    This paper investigates the usefulness of bidirectional multigrid methods for variational optical flow computations. Although these numerical schemes are among the fastest methods for solving equation systems, they are rarely applied in the field of computer vision. We demonstrate how to employ those numerical methods for the treatment of variational optical flow formulations and show that the efficiency of this approach even allows for real-time performance on standard PCs. As a representative for variational optic flow methods, we consider the recently introduced combined local-global method. It can be considered as a noise-robust generalization of the Horn and Schunck technique. We present a decoupled, as well as a coupled, version of the classical Gauss-Seidel solver, and we develop several multgrid implementations based on a discretization coarse grid approximation. In contrast, with standard bidirectional multigrid algorithms, we take advantage of intergrid transfer operators that allow for nondyadic grid hierarchies. As a consequence, no restrictions concerning the image size or the number of traversed levels have to be imposed. In the experimental section, we juxtapose the developed multigrid schemes and demonstrate their superior performance when compared to unidirectional multgrid methods and nonhierachical solvers. For the well-known 316 x 252 Yosemite sequence, we succeeded in computing the complete set of dense flow fields in three quarters of a second on a 3.06-GHz Pentium4 PC. This corresponds to a frame rate of 18 flow fields per second which outperforms the widely-used Gauss-Seidel method by almost three orders of magnitude.

  15. Statistical Inverse Formulation of Optical Flow with Uncertainty Quantification

    CERN Document Server

    Sun, Jie

    2016-01-01

    Optical flow refers to the visual motion observed between two consecutive images. Since the degree of freedom is typically much larger than the constraints imposed by the image observations, the straightforward formulation of optical flow inference is an ill-posed problem. By setting some type of additional "regularity" constraints, classical approaches formulate a well-posed optical flow inference problem in the form of a parameterized set of variational equations. In this work we build a mathematical connection, focused on optical flow methods, between classical variational optical flow approaches and Bayesian statistical inversion. A classical optical flow solution is in fact identical to a maximum a posteriori estimator under the assumptions of linear model with additive independent Gaussian noise and a Gaussian prior distribution. Unlike classical approaches, the statistical inversion approach to optical flow estimation not only allows for "point" estimates, but also provides a distribution of solutions ...

  16. Optical flow based finger stroke detection

    Science.gov (United States)

    Zhu, Zhongdi; Li, Bin; Wang, Kongqiao

    2010-07-01

    Finger stroke detection is an important topic in hand based Human Computer Interaction (HCI) system. Few research studies have carried out effective solutions to this problem. In this paper, we present a novel approach for stroke detection based on mono vision. Via analyzing the optical flow field within the finger area, our method is able to detect finger stroke under various camera position and visual angles. We present a thorough evaluation for each component of the algorithm, and show its efficiency and effectiveness on solving difficult stroke detection problems.

  17. Influenza dell'optic flow sul controllo posturale

    OpenAIRE

    2015-01-01

    The study of optic flow on postural control may explain how self-motion perception contributes to postural stability in young males and females and how such function changes in the old falls risk population. Study I: The aim was to examine the optic flow effect on postural control in young people (n=24), using stabilometry and surface-electromyography. Subjects viewed expansion and contraction optic flow stimuli which were presented full field, in the foveral or in the peripheral visual fi...

  18. Using Optic Flow for the Estimation of Travel Distance

    Directory of Open Access Journals (Sweden)

    Markus Lappe

    2011-05-01

    Full Text Available Much research on optic flow has been concerned with the estimation of heading and the control of the direction of self-motion. In my presentation I will instead focus on a different use of optic flow, namely the estimation of the distance that one has traveled. Optic flow in itself does not provide travel distance, only the combination of distance and speed (time-to-contact is directly available. However, when scaling information from the environment is present, such as the distance to the ground when standing or walking on flat terrain, an integration of the optical velocity can yield ego-speed and travel distance. I will present experiments that show that humans can use optic flow for the estimation of travel distance, but that they often under- and, in some conditions, overestimate a movement's extent. I will then present a model of travel distance estimation from optic flow that is based on leaky path integration.

  19. Micro fibre optic flow checker for the medical analysis application.

    Science.gov (United States)

    Wang, Danping

    2007-01-01

    Two micro fibre optic flow checkers are presented in this paper. They are used for a medical analysis to control a solvent flow up to 1microl/min resolution. A fibre optic sensor as well as a hydraulic system are the principle components of these flow checkers. This paper describes the principle and the experiment setup. It gives the linearity, the repeatability and the stability results.

  20. Optimal Filter Estimation for Lucas-Kanade Optical Flow

    Directory of Open Access Journals (Sweden)

    Remus Brad

    2012-09-01

    Full Text Available Optical flow algorithms offer a way to estimate motion from a sequence of images. The computation of optical flow plays a key-role in several computer vision applications, including motion detection and segmentation, frame interpolation, three-dimensional scene reconstruction, robot navigation and video compression. In the case of gradient based optical flow implementation, the pre-filtering step plays a vital role, not only for accurate computation of optical flow, but also for the improvement of performance. Generally, in optical flow computation, filtering is used at the initial level on original input images and afterwards, the images are resized. In this paper, we propose an image filtering approach as a pre-processing step for the Lucas-Kanade pyramidal optical flow algorithm. Based on a study of different types of filtering methods and applied on the Iterative Refined Lucas-Kanade, we have concluded on the best filtering practice. As the Gaussian smoothing filter was selected, an empirical approach for the Gaussian variance estimation was introduced. Tested on the Middlebury image sequences, a correlation between the image intensity value and the standard deviation value of the Gaussian function was established. Finally, we have found that our selection method offers a better performance for the Lucas-Kanade optical flow algorithm.

  1. Optical wavefront distortion due to supersonic flow fields

    Institute of Scientific and Technical Information of China (English)

    CHEN ZhiQiang; FU Song

    2009-01-01

    The optical wavefront distortion caused by a supersonic flow field around a half model of blunt nose cone was studied in a wind tunnel. A Shack-Hartmann wavefront sensor was used to measure the dis-totted optical wavefront. Interesting optical parameters including the peak variation (PV), root of mean square (RMS) and Strehl ratio were obtained under different test conditions during the experiment. During the establishing process of the flow field in the wind tunnel test section, the wavefront shape was unstable. However after the flow field reached the steady flow state, the wavefront shape kept sta-ble, and the relative error of wavefront aberration was found small. The Shack-Hartmann wavefront sensor developed was proved to be credible in measuring quantitatively the optical phase change of light traveling through the flow field around model window.

  2. Insect-Inspired Optical-Flow Navigation Sensors

    Science.gov (United States)

    Thakoor, Sarita; Morookian, John M.; Chahl, Javan; Soccol, Dean; Hines, Butler; Zornetzer, Steven

    2005-01-01

    Integrated circuits that exploit optical flow to sense motions of computer mice on or near surfaces ( optical mouse chips ) are used as navigation sensors in a class of small flying robots now undergoing development for potential use in such applications as exploration, search, and surveillance. The basic principles of these robots were described briefly in Insect-Inspired Flight Control for Small Flying Robots (NPO-30545), NASA Tech Briefs, Vol. 29, No. 1 (January 2005), page 61. To recapitulate from the cited prior article: The concept of optical flow can be defined, loosely, as the use of texture in images as a source of motion cues. The flight-control and navigation systems of these robots are inspired largely by the designs and functions of the vision systems and brains of insects, which have been demonstrated to utilize optical flow (as detected by their eyes and brains) resulting from their own motions in the environment. Optical flow has been shown to be very effective as a means of avoiding obstacles and controlling speeds and altitudes in robotic navigation. Prior systems used in experiments on navigating by means of optical flow have involved the use of panoramic optics, high-resolution image sensors, and programmable imagedata- processing computers.

  3. Dense Descriptors for Optical Flow Estimation: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Ahmadreza Baghaie

    2017-02-01

    Full Text Available Estimating the displacements of intensity patterns between sequential frames is a very well-studied problem, which is usually referred to as optical flow estimation. The first assumption among many of the methods in the field is the brightness constancy during movements of pixels between frames. This assumption is proven to be not true in general, and therefore, the use of photometric invariant constraints has been studied in the past. One other solution can be sought by use of structural descriptors rather than pixels for estimating the optical flow. Unlike sparse feature detection/description techniques and since the problem of optical flow estimation tries to find a dense flow field, a dense structural representation of individual pixels and their neighbors is computed and then used for matching and optical flow estimation. Here, a comparative study is carried out by extending the framework of SIFT-flow to include more dense descriptors, and comprehensive comparisons are given. Overall, the work can be considered as a baseline for stimulating more interest in the use of dense descriptors for optical flow estimation.

  4. Flow diagnostics using fibre optics

    Indian Academy of Sciences (India)

    B Vasudevan; Srikanth Padbidri; M Chandra Kishore

    2007-02-01

    Research in the area of flow diagnostics using fibre-optics started in our laboratory in early 1998. The first-ever multi-component wind tunnel balance in the world, working with fibre-optic sensors was built and demonstrated in 1999. Since then, several new applications of the technique in the area of fluid dynamic load measurements have been tried successfully. Very recently, fibre-optic sensors have been effectively used for underwater applications, where conventional measurements are relatively very difficult. Since, different physical perturbations affect optical power flowing in a fibre in different ways, unique signatures can be obtained which allow absolute or relative measurement of the incident disturbances. Immunity to electromagnetic or radio frequency interference, high temperature capability, low fatigue, high sensitivity, small size, good corrosion resistance and the capability to embed sensors within the model surface are some of the very attractive features of fibre-optic based instrumentation systems. In this paper, we describe the results of experiments of aerodynamic load measurements at hypersonic speeds (Mach 8·35 and 7·0) and studies carried out recently in a water tunnel over a lifting hypersonic vehicle with a 2-component fibre-optic strain-gauge balance.

  5. Photoacoustic Doppler flow measurement in optically scattering media

    Science.gov (United States)

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-12-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microcirculation with high sensitivity.

  6. Optical flow based velocity estimation for mobile robots

    Science.gov (United States)

    Li, Xiuzhi; Zhao, Guanrong; Jia, Songmin; Qin, Baoling; Yang, Ailin

    2015-02-01

    This paper presents an optical flow based novel technique to perceive the instant motion velocity of mobile robots. The primary focus of this study is to determine the robot's ego-motion using displacement field in temporally consecutive image pairs. In contrast to most previous approaches for estimating velocity, we employ a polynomial expansion based dense optical flow approach and propose a quadratic model based RANSAC refinement of flow fields to render our method more robust with respect to noise and outliers. Accordingly, techniques for geometrical transformation and interpretation of the inter-frame motion are presented. Advantages of our proposal are validated by real experimental results conducted on Pioneer robot.

  7. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  8. Optical density measurements in a multiphase cryogenic fluid flow system

    Science.gov (United States)

    Korman, Valentin; Wiley, John; Gregory, Don A.

    2006-05-01

    An accurate determination of fluid flow in a cryogenic propulsion environment is difficult under the best of circumstances. The extreme thermal environment increases the mechanical constraints, and variable density conditions create havoc with traditional flow measurement schemes. Presented here are secondary results of cryogenic testing of an all-optical sensor capable of a mass flow measurement by directly interrogating the fluid's density state and a determination of the fluid's velocity. The sensor's measurement basis does not rely on any inherent assumptions as to the state of the fluid flow (density or otherwise). The fluid sensing interaction model will be discussed. Current test and evaluation data and future development work will be presented.

  9. Parallel Processor for 3D Recovery from Optical Flow

    Directory of Open Access Journals (Sweden)

    Jose Hugo Barron-Zambrano

    2009-01-01

    Full Text Available 3D recovery from motion has received a major effort in computer vision systems in the recent years. The main problem lies in the number of operations and memory accesses to be performed by the majority of the existing techniques when translated to hardware or software implementations. This paper proposes a parallel processor for 3D recovery from optical flow. Its main feature is the maximum reuse of data and the low number of clock cycles to calculate the optical flow, along with the precision with which 3D recovery is achieved. The results of the proposed architecture as well as those from processor synthesis are presented.

  10. Response properties of cat AMLS neurons to optic flow stimuli

    Institute of Scientific and Technical Information of China (English)

    LI; Baowang(李宝旺); LI; Bing(李兵); CHEN; Hui(陈辉); XU; Ying(徐颖); DIAO; Yuncheng(刁云程)

    2002-01-01

    Spiral and translation stimuli were used to investigate the response properties of cat AMLS (anteromedial lateral suprasylvian area) neurons to optic flow. The overwhelming majority of cells could be significantly excited by the two modes of stimuli and most responsive cells displayed obvious direction selectivity. It is the first time to find a visual area in mammalian brain preferring rotation stimuli. Two representative hypotheses are discussed here on the neural mechanism of optic flow analysis in visual cortex, and some new viewpoints are proposed to explain the experimental results.

  11. Control grid motion estimation for efficient application of optical flow

    CERN Document Server

    Zwart, Christine M

    2012-01-01

    Motion estimation is a long-standing cornerstone of image and video processing. Most notably, motion estimation serves as the foundation for many of today's ubiquitous video coding standards including H.264. Motion estimators also play key roles in countless other applications that serve the consumer, industrial, biomedical, and military sectors. Of the many available motion estimation techniques, optical flow is widely regarded as most flexible. The flexibility offered by optical flow is particularly useful for complex registration and interpolation problems, but comes at a considerable compu

  12. Flow measurement using speckle in optical coherence tomography images

    Science.gov (United States)

    Barton, Jennifer K.; Stromski, Steven

    2005-04-01

    Doppler optical coherence tomography (DOCT) is a valuable tool for depth-resolved flow measurements in tissue. However, DOCT suffers from two disadvantages: it is insensitive to flow in the direction normal to the imaging beam, and it requires knowledge of the phase of the demodulated signal. We present an alternative method of extracting flow information, using speckle of conventional amplitude optical coherence tomography images. The two techniques can be shown to be essentially equivalent, with the distinction that speckle methods are sensitive to flow in all directions but do not provide information on the direction of flow. It is well known in other imaging modalities that moving scatterers cause a time-varying speckle pattern. Due to the pixel-by-pixel acquisition scheme of conventional OCT, time-varying speckle is manifested as a change of OCT image spatial speckle frequencies. We tested the ability of speckle to provide quantitative flow information using a flow phantom (a tube filled with Intralipid flowing at a constant volumetric flow rate). Initially, m-scans were taken at over the center of the tube. Images were averaged to reduce noise and the region corresponding to the center one-quarter of the tube lumen was selected. Sequential a-scans were concatenated, the Fourier transform performed, and a ratio of high to low spatial frequencies computed. We found that, over a range of velocities, this ratio bore a linear relation to flow velocity. For two-dimensional imaging, the program was modified to use a sliding window. Parabolic flow profile was visualized inside the tube. This study shows the feasibility of extracting quantitative flow data in all directions without phase information.

  13. Flow patterns on spectral-domain optical coherence tomography reveal flow directions at retinal vessel bifurcations

    DEFF Research Database (Denmark)

    Willerslev, Anne; Li, Xiao Q; Munch, Inger C

    2014-01-01

    PURPOSE: To study intravascular characteristics of flowing blood in retinal vessels using spectral-domain optical coherence tomography (SD-OCT). METHODS: Examination of selected arterial bifurcations and venous sites of confluence in 25 healthy 11-year-old children recruited as an ad hoc subsample...... be determined using SD-OCT. This feature may assist the identification of flow reversal near sites of vascular occlusion, the analysis of blood flow near vascular malformations and the segmentation of retinal SD-OCT images....

  14. Discontinuity-preserving optical flow algorithm

    Institute of Scientific and Technical Information of China (English)

    Yuan Lei; Li Jinzong; Li Dongdong

    2007-01-01

    A modification of Horn and Schunk's approach is investigated, which leads to a better preservation of flow discontinuities.It improves Horn-Schunk model in three aspects: (1) It replaces the smooth weight coefficient in the energy equation by the variable weight coefficient.(2) It adopts a novel method to compute the mean velocity.The novel method also reflects the effect of the intensity difference on the image velocity diffusion.(3) It introduces a more efficient iterative method than the Gauss-Seidel method to solve the associated Euler-Lagrange equation.The experiment results validate the better effect of the improved method on preserving discontinuities.

  15. Optical diagnostics for turbulent and multiphase flows: Particle image velocimetry and photorefractive optics

    Energy Technology Data Exchange (ETDEWEB)

    O`Hern, T.J.; Torczynski, J.R.; Shagam, R.N.; Blanchat, T.K.; Chu, T.Y.; Tassin-Leger, A.L.; Henderson, J.A.

    1997-01-01

    This report summarizes the work performed under the Sandia Laboratory Directed Research and Development (LDRD) project ``Optical Diagnostics for Turbulent and Multiphase Flows.`` Advanced optical diagnostics have been investigated and developed for flow field measurements, including capabilities for measurement in turbulent, multiphase, and heated flows. Particle Image Velocimetry (PIV) includes several techniques for measurement of instantaneous flow field velocities and associated turbulence quantities. Nonlinear photorefractive optical materials have been investigated for the possibility of measuring turbulence quantities (turbulent spectrum) more directly. The two-dimensional PIV techniques developed under this LDRD were shown to work well, and were compared with more traditional laser Doppler velocimetry (LDV). Three-dimensional PIV techniques were developed and tested, but due to several experimental difficulties were not as successful. The photorefractive techniques were tested, and both potential capabilities and possible problem areas were elucidated.

  16. Fiber optic liquid mass flow sensor and method

    Science.gov (United States)

    Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)

    2010-01-01

    A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.

  17. Optical Flow Structure Effects in Children’s Postural Control

    Science.gov (United States)

    Barela, José A.

    2016-01-01

    The aim of this study was to investigate the effect of distance and optic flow structure on visual information and body sway coupling in children and young adults. Thirty children (from 4 to 12 years of age) and 10 young adults stood upright inside of a moving room oscillating at 0.2 Hz, at 0.25 and 1.5 m from the front wall, and under three optical flow conditions (global, central, and peripheral). Effect of distance and optic flow structure on the coupling of visual information and body sway is age-dependent, with 4-year-olds being more affected at 0.25 m distance than older children and adults are. No such difference was observed at 1.5 m from the front wall. Moreover, 4-year-olds’ sway was larger and displayed higher variability. These results suggest that despite being able to accommodate change resulting from varying optic flow conditions, young children have difficulty in dodging stronger visual stimuli. Lastly, difference in sway performance may be due to immature inter-modality sensory reweighting. PMID:27352305

  18. Crowd Analysis by Using Optical Flow and Density Based Clustering

    DEFF Research Database (Denmark)

    Santoro, Francesco; Pedro, Sergio; Tan, Zheng-Hua

    2010-01-01

    In this paper, we present a system to detect and track crowds in a video sequence captured by a camera. In a first step, we compute optical flows by means of pyramidal Lucas-Kanade feature tracking. Afterwards, a density based clustering is used to group similar vectors. In the last step...

  19. Self-motion Perception from Optic Flow and Rotation Signals

    NARCIS (Netherlands)

    J.A. Beintema (Jaap)

    2000-01-01

    textabstractThe value of optic flow for retrieving movement direction was recognised already two centuries ago by astronomers, searching the sky for meteorite showers. The point from which the shower appeared to emanate they termed the radiant, knowing it indicated the direction along which the mete

  20. Optically measured microvascular blood flow contrast of malignant breast tumors.

    Directory of Open Access Journals (Sweden)

    Regine Choe

    Full Text Available Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS, a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63; tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66, and using normal tissue in the contralateral breast was 2.27 (1.90-2.70. Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography.

  1. Self-motion Perception from Optic Flow and Rotation Signals

    NARCIS (Netherlands)

    J.A. Beintema (Jaap)

    2000-01-01

    textabstractThe value of optic flow for retrieving movement direction was recognised already two centuries ago by astronomers, searching the sky for meteorite showers. The point from which the shower appeared to emanate they termed the radiant, knowing it indicated the direction along which the mete

  2. Nocturnal insects use optic flow for flight control.

    Science.gov (United States)

    Baird, Emily; Kreiss, Eva; Wcislo, William; Warrant, Eric; Dacke, Marie

    2011-08-23

    To avoid collisions when navigating through cluttered environments, flying insects must control their flight so that their sensory systems have time to detect obstacles and avoid them. To do this, day-active insects rely primarily on the pattern of apparent motion generated on the retina during flight (optic flow). However, many flying insects are active at night, when obtaining reliable visual information for flight control presents much more of a challenge. To assess whether nocturnal flying insects also rely on optic flow cues to control flight in dim light, we recorded flights of the nocturnal neotropical sweat bee, Megalopta genalis, flying along an experimental tunnel when: (i) the visual texture on each wall generated strong horizontal (front-to-back) optic flow cues, (ii) the texture on only one wall generated these cues, and (iii) horizontal optic flow cues were removed from both walls. We find that Megalopta increase their groundspeed when horizontal motion cues in the tunnel are reduced (conditions (ii) and (iii)). However, differences in the amount of horizontal optic flow on each wall of the tunnel (condition (ii)) do not affect the centred position of the bee within the flight tunnel. To better understand the behavioural response of Megalopta, we repeated the experiments on day-active bumble-bees (Bombus terrestris). Overall, our findings demonstrate that despite the limitations imposed by dim light, Megalopta-like their day-active relatives-rely heavily on vision to control flight, but that they use visual cues in a different manner from diurnal insects.

  3. Power flow from a dipole emitter near an optical antenna.

    Science.gov (United States)

    Huang, Kevin C Y; Jun, Young Chul; Seo, Min-Kyo; Brongersma, Mark L

    2011-09-26

    Current methods to calculate the emission enhancement of a quantum emitter coupled to an optical antenna of arbitrary geometry rely on analyzing the total Poynting vector power flow out of the emitter or the dyadic Green functions from full-field numerical simulations. Unfortunately, these methods do not provide information regarding the nature of the dominant energy decay pathways. We present a new approach that allows for a rigorous separation, quantification, and visualization of the emitter output power flow captured by an antenna and the subsequent reradiation power flow to the far field. Such analysis reveals unprecedented details of the emitter/antenna coupling mechanisms and thus opens up new design strategies for strongly interacting emitter/antenna systems used in sensing, active plasmonics and metamaterials, and quantum optics.

  4. RELIABLE VALIDATION BASED ON OPTICAL FLOW VISUALIZATION FOR CFD SIMULATIONS

    Institute of Scientific and Technical Information of China (English)

    姜宗林

    2003-01-01

    A reliable validation based on the optical flow visualization for numerical simulations of complex flowfields is addressed in this paper.Several test cases,including two-dimensional,axisymmetric and three-dimensional flowfields,were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields.In the validation,images of these flowfields were constructed from numerical results based on the principle of the optical flow visualization,and compared directly with experimental interferograms.Because both experimental and numerical results are of identical physical representation,the agreement between them can be evaluated effectively by examining flow structures as well as checking discrepancies in density.The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.

  5. Determination of Horizontal Motion through Optical Flow Computations

    Institute of Scientific and Technical Information of China (English)

    俞志和; FrankM.Caimi

    1997-01-01

    For intelligent/autonomous subsea vehicles,reliable short-range horizontal positioning is difficult to achieve,particularly over flat bottom topography.A potential solution proposed in this paper utilized a passive optical sensing method to estimate the vehicle displacement using the bottom surface texture.The suggested optical flow method does not require any feature correspondences in images and it is robust in allowing brightness changes between image frames.Fundamentally,this method is similar to correlation methods attempting to match images and compute the motion disparity.However,in correlation methods,searching a neighbor region blindly for best match is lengthy.Main contributions of this paper come from the analysis showing that optical flow computation based on the general model cannot avoid errors except for null motion although the sign of optical flow keeps correct,and from the development of an iterative shifting method based on the error characteristics to accurately determine motions.Advantages of the proposed method are verified by real image experiments.

  6. RELIABLE VALIDATION BASED ON OPTICAL FLOW VISUALIZATION FOR CFD SIMULATIONS

    Institute of Scientific and Technical Information of China (English)

    姜宗林

    2003-01-01

    A reliable validation based on the optical flow visualization for numerical simula-tions of complex flowfields is addressed in this paper. Several test cases, including two-dimensional,axisymmetric and three-dimensional flowfields, were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields. In the validation, imagesof these flowfields were constructed from numerical results based on the principle of the optical flowvisualization, and compared directly with experimental interferograms. Because both experimental and numerical results axe of identical physical representation, the agreement between them can be evaluatedeffectively by examining flow structures as well as checking discrepancies in density. The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.

  7. Vision System for Relative Motion Estimation from Optical Flow

    Directory of Open Access Journals (Sweden)

    Sergey M. Sokolov

    2010-08-01

    Full Text Available For the recent years there was an increasing interest in different methods of motion analysis based on visual data acquisition. Vision systems, intended to obtain quantitative data regarding motion in real time are especially in demand. This paper talks about the vision systems that allow the receipt of information on relative object motion in real time. It is shown, that the algorithms solving a wide range of practical problems by definition of relative movement can be generated on the basis of the known algorithms of an optical flow calculation. One of the system's goals is the creation of economically efficient intellectual sensor prototype in order to estimate relative objects motion based on optic flow. The results of the experiments with a prototype system model are shown.

  8. Optic flow stabilizes flight in ruby-throated hummingbirds.

    Science.gov (United States)

    Ros, Ivo G; Biewener, Andrew A

    2016-08-15

    Flying birds rely on visual cues for retinal image stabilization by negating rotation-induced optic flow, the motion of the visual panorama across the retina, through corrective eye and head movements. In combination with vestibular and proprioceptive feedback, birds may also use visual cues to stabilize their body during flight. Here, we test whether artificially induced wide-field motion generated through projected visual patterns elicits maneuvers in body orientation and flight position, in addition to stabilizing vision. To test this hypothesis, we present hummingbirds flying freely within a 1.2 m cylindrical visual arena with a virtual surround rotated at different speeds about its vertical axis. The birds responded robustly to these visual perturbations by rotating their heads and bodies with the moving visual surround, and by adjusting their flight trajectories, following the surround. Thus, similar to insects, hummingbirds appear to use optic flow cues to control flight maneuvers as well as to stabilize their visual inputs.

  9. Detection of Abnormal Events via Optical Flow Feature Analysis

    Directory of Open Access Journals (Sweden)

    Tian Wang

    2015-03-01

    Full Text Available In this paper, a novel algorithm is proposed to detect abnormal events in video streams. The algorithm is based on the histogram of the optical flow orientation descriptor and the classification method. The details of the histogram of the optical flow orientation descriptor are illustrated for describing movement information of the global video frame or foreground frame. By combining one-class support vector machine and kernel principal component analysis methods, the abnormal events in the current frame can be detected after a learning period characterizing normal behaviors. The difference abnormal detection results are analyzed and explained. The proposed detection method is tested on benchmark datasets, then the experimental results show the effectiveness of the algorithm.

  10. Postural adaptations to repeated optic flow stimulation in older adults.

    Science.gov (United States)

    O'Connor, Kathryn W; Loughlin, Patrick J; Redfern, Mark S; Sparto, Patrick J

    2008-10-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of three conditions were performed: (1) constant 12 cm optic flow amplitude (24 cm peak-to-peak), (2) constant 4 cm amplitude (8 cm p-t-p), and (3) a transition in amplitude from 4 to 12 cm. The average power of head sway velocity (P(vel)) was calculated for consecutive 5s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the P(vel). P(vel) was greater in older adults in all conditions (phabituation. P(vel) of the older adults decreased significantly between all 3 trials, but decreased only between Trials 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12 cm did not significantly change, older adults had an increase in P(vel) following the transition, ranging from 6.5 dB for the first trial to 3.4 dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization.

  11. Motion compensated frame interpolation with a symmetric optical flow constraint

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau; Roholm, Lars; Bruhn, Andrés;

    2012-01-01

    We consider the problem of interpolating frames in an image sequence. For this purpose accurate motion estimation can be very helpful. We propose to move the motion estimation from the surrounding frames directly to the unknown frame by parametrizing the optical flow objective function such that ......We consider the problem of interpolating frames in an image sequence. For this purpose accurate motion estimation can be very helpful. We propose to move the motion estimation from the surrounding frames directly to the unknown frame by parametrizing the optical flow objective function...... such that the interpolation assumption is directly modeled. This reparametrization is a powerful trick that results in a number of appealing properties, in particular the motion estimation becomes more robust to noise and large displacements, and the computational workload is more than halved compared to usual bidirectional...... methods. The proposed reparametrization is generic and can be applied to almost every existing algorithm. In this paper we illustrate its advantages by considering the classic TV-L1 optical flow algorithm as a prototype. We demonstrate that this widely used method can produce results that are competitive...

  12. Optical Flow Cell for Measuring Size, Velocity and Composition of Flowing Droplets

    Directory of Open Access Journals (Sweden)

    Sammer-ul Hassan

    2017-02-01

    Full Text Available Here an optical flow cell with two light paths is reported that can accurately quantify the size and velocity of droplets flowing through a microchannel. The flow cell can measure the time taken for droplets to pass between and through two conjoined light paths, and thereby is capable of measuring the velocities (0.2–5.45 mm/s and sizes of droplets (length > 0.8 mm. The composition of the droplet can also be accurately quantified via optical absorption measurements. The device has a small footprint and uses low-powered, low-cost components, which make it ideally suited for use in field-deployable and portable analytical devices.

  13. Design of Optical Wireless Networks with Fair Traffic Flows

    Directory of Open Access Journals (Sweden)

    Artur Tomaszewski

    2014-01-01

    Full Text Available The paper presents a method for optimising the wireless optical network that carries elastic packet traffic. The particular focus is on modelling the effect of elastic traffic flows slowing down in response to the decrease of the optical transmission systems’ capacity at bad weather conditions. A mathematical programming model of the network design problem is presented that assumes that the packet rates of elastic traffic flows decrease fairly. While practically any subset of network links can be simultaneously affected by unfavourable transmission conditions, a particular challenge of solving the problem results from a huge number of network states considered in the model. Therefore, how the problem can be solved by generating the most unfavourable network states is presented. Moreover, it is proved that it is entirely sufficient to consider only the states that correspond to the decrease of capacity on a single link. Finally, as the general problem is nonlinear, it is shown that the problem can be transformed to a linear MIP problem and solved effectively when single-path routing of traffic flows is assumed.

  14. Optical Electronic Bragg Reflection Sensor System with Hydrodynamic Flow Applications

    Science.gov (United States)

    Lyons, D. R.

    2003-01-01

    This project, as described in the following report, involved design and fabrication of fiber optic sensors for the detection and measurement of dynamic fluid density variations. These devices are created using UV (ultraviolet) ablation and generally modified transverse holographic fiber grating techniques. The resulting phase gratings created on or immediately underneath the flat portion of D-shaped optical waveguides are characterized as evanescent field sensing devices. The primary applications include the sensor portion of a real-time localized or distributed measurement system for hydrodynamic flow, fluid density measurements, and phase change phenomena. Several design modifications were implemented in an attempt to accomplish the tasks specified in our original proposal. In addition, we have established key collaborative relationships with numerous people and institutions.

  15. Low Delay Wyner-Ziv Coding Using Optical Flow

    DEFF Research Database (Denmark)

    Salmistraro, Matteo; Forchhammer, Søren

    2014-01-01

    Distributed Video Coding (DVC) is a video coding paradigm that exploits the source statistics at the decoder based on the availability of the Side Information (SI). The SI can be seen as a noisy version of the source, and the lower the noise the higher the RD performance of the decoder. The SI...... on preceding frames for the generation of the SI by means of Optical Flow (OF), which is also used in the refinement step of the SI for enhanced RD performance. Compared with a state-of-the-art extrapolation-based decoder the proposed solution achieves RD Bjontegaard gains up to 1.3 dB....

  16. Optical flow with structure information for epithelial image mosaicing.

    Science.gov (United States)

    Ali, Sharib; Faraz, Khuram; Daul, Christian; Blondel, Walter

    2015-01-01

    Mosaicing of biological tissue surfaces is challenging due to the weak image textures. This contribution presents a mosaicing algorithm based on a robust and accurate variational optical flow scheme. A Riesz pyramid based multiscale approach aims at overcoming the "flattening-out" problem at coarser levels. Moreover, the structure information present in images of epithelial surfaces is incorporated into the data-term to improve the algorithm robustness. The algorithm accuracy is first assessed with simulated sequences and then used for mosaicing standard clinical endoscopic data.

  17. Evaluation of nozzle shapes for an optical flow meter

    Science.gov (United States)

    Sheikholeslami, M. Z.; Patel, B. R.

    1992-05-01

    Numerical modeling is performed for turbulent flow in axisymmetric nozzles using Creare's computer program FLUENT/BFC. The primary objective of the project was to assist Spectron Development Laboratories in selecting an optimum nozzle shape for an optical flowmeter. The nozzle performance is evaluated for various length to diameter ratios, area contraction ratios, and Reynolds numbers. The computations have demonstrated that a cubic profile nozzle with length to diameter ratio of 1.6 and area contraction ratio of 6.2 can decrease the velocity profile non-uniformity from 15 percent at the entrance to 1 percent at the exit. The configuration is recommended for further investigation.

  18. Architecture Design and Experimental Platform Demonstration of Optical Network based on OpenFlow Protocol

    Science.gov (United States)

    Xing, Fangyuan; Wang, Honghuan; Yin, Hongxi; Li, Ming; Luo, Shenzi; Wu, Chenguang

    2016-02-01

    With the extensive application of cloud computing and data centres, as well as the constantly emerging services, the big data with the burst characteristic has brought huge challenges to optical networks. Consequently, the software defined optical network (SDON) that combines optical networks with software defined network (SDN), has attracted much attention. In this paper, an OpenFlow-enabled optical node employed in optical cross-connect (OXC) and reconfigurable optical add/drop multiplexer (ROADM), is proposed. An open source OpenFlow controller is extended on routing strategies. In addition, the experiment platform based on OpenFlow protocol for software defined optical network, is designed. The feasibility and availability of the OpenFlow-enabled optical nodes and the extended OpenFlow controller are validated by the connectivity test, protection switching and load balancing experiments in this test platform.

  19. Real-time planar flow velocity measurements using an optical flow algorithm implemented on GPU

    CERN Document Server

    Gautier, N

    2013-01-01

    This paper presents a high speed implementation of an optical flow algorithm which computes planar velocity fields in an experimental flow. Real-time computation of the flow velocity field allows the experimentalist to have instantaneous access to quantitative features of the flow. This can be very useful in many situations: fast evaluation of the performances and characteristics of a new setup, design optimization, easier and faster parametric studies, etc. It can also be a valuable measurement tool for closed-loop flow control experiments where fast estimation of the state of the flow is needed. The algorithm is implemented on a Graphics Processing Unit (GPU). The accuracy of the computation is shown. Computation speed and scalability are highlighted along with guidelines for further improvements. The system architecture is flexible, scalable and can be adapted on the fly in order to process higher resolutions or achieve higher precision. The set-up is applied on a Backward-Facing Step (BFS) flow in a hydro...

  20. Polarization-, carrier-, and format-selectable optical flow generation based on a multi-flow transmitter using passive polymers

    DEFF Research Database (Denmark)

    Katopodis, V.; Spyropoulou, M.; Tsokos, C.;

    2016-01-01

    . Multiflow operation is realized by two polymer boards allowing optical carrier management and optional polarization multiplexing on chip. Optical carrier generation is performed also on chip using three tunable InP gain chips hybridly integrated on the input polyboard. Single and dual optical flow...

  1. Optic Flow Information Influencing Heading Perception during Rotation

    Directory of Open Access Journals (Sweden)

    Diederick C. Niehorster

    2011-05-01

    Full Text Available We investigated what roles global spatial frequency, surface structure, and foreground motion play in heading perception during simulated rotation from optic flow. The display (110°Hx94°V simulated walking on a straight path over a ground plane (depth range: 1.4–50 m at 2 m/s while fixating a target off to one side (mean R/T ratios: ±1, ±2, ±3 under six display conditions. Four displays consisted of nonexpanding dots that were distributed so as to manipulate the amount of foreground motion and the presence of surface structure. In one further display the ground was covered with disks that expanded during the trial and lastly a textured ground display was created with the same spatial frequency power spectrum as the disk ground. At the end of each 1s trial, observers indicated their perceived heading along a line at the display's center. Mean heading biases were smaller for the textured than for the disk ground, for the displays with more foreground motion and for the displays with surface structure defined by dot motion than without. We conclude that while spatial frequency content is not a crucial factor, dense motion parallax and surface structure in optic flow are important for accurate heading perception during rotation.

  2. Visual guidance based on optic flow: a biorobotic approach.

    Science.gov (United States)

    Franceschini, Nicolas

    2004-01-01

    This paper addresses some basic questions as to how vision links up with action and serves to guide locomotion in both biological and artificial creatures. The thorough knowledge gained during the past five decades on insects' sensory-motor abilities and the neuronal substrates involved has provided us with a rich source of inspiration for designing tomorrow's self-guided vehicles and micro-vehicles, which will be able to cope with unforeseen events on the ground, under water, in the air, in space, on other planets, and inside the human body. Insects can teach us some useful tricks for designing agile autonomous robots. Since constructing a "biorobot" first requires exactly formulating the biological principles presumably involved, it gives us a unique opportunity of checking the soundness and robustness of these principles by bringing them face to face with the real physical world. "Biorobotics" therefore goes one step beyond computer simulation. It leads to experimenting with real physical robots which have to pass the stringent test of the real world. Biorobotics provide us with a new tool, which can help neurobiologists and neuroethologists to identify and investigate worthwhile issues in the field of sensory-motor control. Here we describe some of the visually guided terrestrial and aerial robots we have developed since 1985 on the basis of our biological findings. All these robots behave in response to the optic flow, i.e., they work by measuring the slip speed of the retinal image. Optic flow is sensed on-board by miniature electro-optical velocity sensors. The very principle of these sensors was based on studies in which we recorded the responses of single identified neurons to single photoreceptor stimulation in a model visual system: the fly's compound eye.

  3. Effect of oxygen flow on the structure and optical properties of the Gd2O3 optical films

    Science.gov (United States)

    Wang, Siyu; Ma, Ping; Pu, Yunti; Qiao, Zhao; Zhang, Mingxiao; Lu, Zhongwen; Peng, Dongxu

    2016-10-01

    Gd2O3 thin films were deposited by Ion-beam sputtering (IBS) under the oxygen flow of 0 sccm~30 sccm. The structure and optical properties of the Gd2O3 optical films were investigated by Lambdar950 spectrophotometer, laser calorimetry and atomic force microscopy (AFM). When oxygen flow was less than 10 sccm, with the increase of oxygen flow, the transmittance of the films increased, at the same time absorptance and the surface roughness of the films decreased. While the flow was more than 10 sccm, with the increase of the flow rate, the surface roughness of the films increased, but the transmittance and absorptance did not show any apparent change. The results show that both the structure and optical properties are closely related to the flow of oxygen. XPS measurements demonstrated that when the oxygen flow increase from 0 sccm to 10 sccm, the defect oxygen decreases. But when the oxygen flow increase from 10 sccm to 30 sccm, the defect oxygen increase. The XPS spectra show that when the oxygen flow was 10 sccm, the defect oxygen was the least. Thus when the oxygen flow was 10 sccm, the structure and optical properties of the Gd2O3 optical films were the best.

  4. Quantitative interferometric microscopy cytometer based on regularized optical flow algorithm

    Science.gov (United States)

    Xue, Liang; Vargas, Javier; Wang, Shouyu; Li, Zhenhua; Liu, Fei

    2015-09-01

    Cell detections and analysis are important in various fields, such as medical observations and disease diagnoses. In order to analyze the cell parameters as well as observe the samples directly, in this paper, we present an improved quantitative interferometric microscopy cytometer, which can monitor the quantitative phase distributions of bio-samples and realize cellular parameter statistics. The proposed system is able to recover the phase imaging of biological samples in the expanded field of view via a regularized optical flow demodulation algorithm. This algorithm reconstructs the phase distribution with high accuracy with only two interferograms acquired at different time points simplifying the scanning system. Additionally, the method is totally automatic, and therefore it is convenient for establishing a quantitative phase cytometer. Moreover, the phase retrieval approach is robust against noise and background. Excitingly, red blood cells are readily investigated with the quantitative interferometric microscopy cytometer system.

  5. Crowd Analysis by Using Optical Flow and Density Based Clustering

    DEFF Research Database (Denmark)

    Santoro, Francesco; Pedro, Sergio; Tan, Zheng-Hua;

    2010-01-01

    , it is applied a crowd tracker in every frame, allowing us to detect and track the crowds. Our system gives the output as a graphic overlay, i.e it adds arrows and colors to the original frame sequence, in order to identify crowds and their movements. For the evaluation, we check when our system detect certains......In this paper, we present a system to detect and track crowds in a video sequence captured by a camera. In a first step, we compute optical flows by means of pyramidal Lucas-Kanade feature tracking. Afterwards, a density based clustering is used to group similar vectors. In the last step...... events on the crowds, such as merging, splitting and collision....

  6. Eigenanalysis of a neural network for optic flow processing

    Science.gov (United States)

    Weber, F.; Eichner, H.; Cuntz, H.; Borst, A.

    2008-01-01

    Flies gain information about self-motion during free flight by processing images of the environment moving across their retina. The visual course control center in the brain of the blowfly contains, among others, a population of ten neurons, the so-called vertical system (VS) cells that are mainly sensitive to downward motion. VS cells are assumed to encode information about rotational optic flow induced by self-motion (Krapp and Hengstenberg 1996 Nature 384 463-6). Recent evidence supports a connectivity scheme between the VS cells where neurons with neighboring receptive fields are connected to each other by electrical synapses at the axonal terminals, whereas the boundary neurons in the network are reciprocally coupled via inhibitory synapses (Haag and Borst 2004 Nat. Neurosci. 7 628-34 Farrow et al 2005 J. Neurosci. 25 3985-93 Cuntz et al 2007 Proc. Natl Acad. Sci. USA). Here, we investigate the functional properties of the VS network and its connectivity scheme by reducing a biophysically realistic network to a simplified model, where each cell is represented by a dendritic and axonal compartment only. Eigenanalysis of this model reveals that the whole population of VS cells projects the synaptic input provided from local motion detectors on to its behaviorally relevant components. The two major eigenvectors consist of a horizontal and a slanted line representing the distribution of vertical motion components across the fly's azimuth. They are, thus, ideally suited for reliably encoding translational and rotational whole-field optic flow induced by respective flight maneuvers. The dimensionality reduction compensates for the contrast and texture dependence of the local motion detectors of the correlation-type, which becomes particularly pronounced when confronted with natural images and their highly inhomogeneous contrast distribution.

  7. Peripheral processing facilitates optic flow-based depth perception

    Directory of Open Access Journals (Sweden)

    Jinglin Li

    2016-10-01

    Full Text Available Flying insects, such as flies or bees, rely on consistent information regarding the depth structure of the environment when performing their flight maneuvers in cluttered natural environments. These behaviors include avoiding collisions, approaching targets or spatial navigation. Insects are thought to obtain depth information visually from the retinal image displacements (`optic flow' during translational ego-motion. Optic flow in the insect visual system is processed by a mechanism that can be modeled by correlation-type elementary motion detectors (EMDs. However, it is still an open question how spatial information can be extracted reliably from the responses of the highly contrast- and pattern-dependent EMD responses, especially if the vast range of light intensities encountered in natural environments is taken into account. This question will be addressed here by systematically modeling the peripheral visual system of flies, including various adaptive mechanisms. Different model variants of the peripheral visual system were stimulated with image sequences that mimic the panoramic visual input during translational ego-motion in various natural environments, and the resulting peripheral signals were fed into an array of EMDs. We characterized the influence of each peripheral computational unit on the representation of spatial information in the EMD responses. Our model simulations reveal that information about the overall light level needs to be eliminated from the EMD input as is accomplished under light-adapted conditions in the insect peripheral visual system. The response characteristics of large monopolar cells resemble that of a band-pass filter, which reduces the contrast dependency of EMDs strongly, effectively enhancing the representation of the nearness of objects and, especially, of their contours. We furthermore show that local brightness adaptation of photoreceptors allows for spatial vision under a wide range of dynamic light

  8. Detection of linear ego-acceleration from optic flow.

    Science.gov (United States)

    Festl, Freya; Recktenwald, Fabian; Yuan, Chunrong; Mallot, Hanspeter A

    2012-07-20

    Human observers are able to estimate various ego-motion parameters from optic flow, including rotation, translational heading, time-to-collision (TTC), time-to-passage (TTP), etc. The perception of linear ego-acceleration or deceleration, i.e., changes of translational velocity, is less well understood. While time-to-passage experiments indicate that ego-acceleration is neglected, subjects are able to keep their (perceived) speed constant under changing conditions, indicating that some sense of ego-acceleration or velocity change must be present. In this paper, we analyze the relation of ego-acceleration estimates and geometrical parameters of the environment using simulated flights through cylindrical and conic (narrowing or widening) corridors. Theoretical analysis shows that a logarithmic ego-acceleration parameter, called the acceleration rate ρ, can be calculated from retinal acceleration measurements. This parameter is independent of the geometrical layout of the scene; if veridical ego-motion is known at some instant in time, acceleration rate allows updating of ego-motion without further depth-velocity calibration. Results indicate, however, that subjects systematically confuse ego-acceleration with corridor narrowing and ego-deceleration with corridor widening, while veridically judging ego-acceleration in straight corridors. We conclude that judgments of ego-acceleration are based on first-order retinal flow and do not make use of acceleration rate or retinal acceleration.

  9. Laser speckle contrast imaging of cerebral blood flow of newborn mice at optical clearing

    Science.gov (United States)

    Timoshina, Polina A.; Zinchenko, Ekaterina M.; Tuchina, Daria K.; Sagatova, Madina M.; Semyachkina-Glushkovskaya, Oxana V.; Tuchin, Valery V.

    2017-03-01

    In this work, we consider the use of optical clearing agents to improve imaging quality of the cerebral blood flow of newborn mice. Aqueous 60%-glycerol solution, aqueous 70%-OmnipaqueTM(300) solution and OmnipaqueTM (300) solution in water/DMSO(25%/5%) were selected as the optical clearing agents. Laser speckle contrast imaging (LSCI) was used for imaging of cerebral blood flow in newborn mice brain during topical optical clearing of tissuesin the area of the fontanelle. These results demonstrate the effectiveness of glycerol and Omnipaque solutions as optical clearing agents for investigation of cerebral blood flow in newborn mice without scalp removing and skull thinning.

  10. An Object Detection Method Using Wavelet Optical Flow and Hybrid Linear-Nonlinear Classifier

    Directory of Open Access Journals (Sweden)

    Pengcheng Han

    2013-01-01

    Full Text Available We propose a new computational intelligence method using wavelet optical flow and hybrid linear-nonlinear classifier for object detection. With the existing optical flow methods, it is difficult to accurately estimate moving objects with diverse speeds. We propose a wavelet-based optical flow method, which uses wavelet decomposition in optical flow motion estimation. The algorithm can accurately detect moving objects with variable speeds in a scene. In addition, we use the hybrid linear-nonlinear classifier (HLNLC to classify moving objects and static background. HLNLC transforms a nonoptimal scalar variable into its likelihood ratio and uses a scalar quantity as the decision variable. This approach is appropriate for the classification of optical flow feature vectors with unequal variance matrices. The experimental results confirm that our proposed object detection method has an improved accuracy and computation efficiency over other state-of-the-art methods.

  11. Design of flow chamber with electronic cell volume capability and light detection optics for multilaser flow cytometry.

    Science.gov (United States)

    Schuette, W H; Shackney, S E; Plowman, F A; Tipton, H W; Smith, C A; MacCollum, M A

    1984-11-01

    A multibeam optical detection system has been developed with a high optical efficiency, achieved through a reduction in the number of optical interfaces employed in the system. This reduction is made possible by a combination of employing simple lenses, gluing the objective lens directly upon the face of the flow cuvette and the extraction of only one fluorescence signal from each laser beam. A modified flow chamber is also described that includes fluidic resistance elements for the elimination of most of the electric shielding normally associated with electronic cell volume measurements.

  12. Automatic analysis of ciliary beat frequency using optical flow

    Science.gov (United States)

    Figl, Michael; Lechner, Manuel; Werther, Tobias; Horak, Fritz; Hummel, Johann; Birkfellner, Wolfgang

    2012-02-01

    Ciliary beat frequency (CBF) can be a useful parameter for diagnosis of several diseases, as e.g. primary ciliary dyskinesia. (PCD). CBF computation is usually done using manual evaluation of high speed video sequences, a tedious, observer dependent, and not very accurate procedure. We used the OpenCV's pyramidal implementation of the Lukas-Kanade algorithm for optical flow computation and applied this to certain objects to follow the movements. The objects were chosen by their contrast applying the corner detection by Shi and Tomasi. Discrimination between background/noise and cilia by a frequency histogram allowed to compute the CBF. Frequency analysis was done using the Fourier transform in matlab. The correct number of Fourier summands was found by the slope in an approximation curve. The method showed to be usable to distinguish between healthy and diseased samples. However there remain difficulties in automatically identifying the cilia, and also in finding enough high contrast cilia in the image. Furthermore the some of the higher contrast cilia are lost (and sometimes found) by the method, an easy way to distinguish the correct sub-path of a point's path have yet to be found in the case where the slope methods doesn't work.

  13. Clinical use of optical coherence tomography and fractional flow reserve

    Directory of Open Access Journals (Sweden)

    Ivanović Vladimir

    2016-01-01

    Full Text Available Introduction. The aim of each diagnostic method is to serve as a guide in deciding about the right patient treatment. During myocardial revascularization the decision to perform revascularization is usually not easy to make, especially in case of borderline stenosis. It has been proven that it is not enough to base morphological evaluation of coronary artery vessel stenosis solely on angiography. It is necessary to include additional modern diagnostic methods for functional analysis and detailed morphological analysis using fractional flow reserve (FFR and optical coherence tomography (OCT, respectively. Case reports. In the first case report we showed the significance of morphological analysis using OCT and proved that it was not lumen stenosis. The second and the third case reports showed the complementarity between functional analysis (FFR and morphological analysis (OCT of stenosis in solving a complex coronary disease. The fourth case report showed the significance of OCT in dealing with the recurrent stent restenosis. Conclusion. By these short case reports we confirmed that percutaneous coronary intervention (PCI guided by angiography is definitely not enough in deciding about myocardial revascularization especially in patients with a complex coronary disease. In certain cases FFR and OCT procedures can be complementary methods and improve quality of revascularization, particularly in the case of recurrent in-stent restenosis.

  14. Real time mass flow rate measurement using multiple fan beam optical tomography.

    Science.gov (United States)

    Abdul Rahim, R; Leong, L C; Chan, K S; Rahiman, M H; Pang, J F

    2008-01-01

    This paper presents the implementing multiple fan beam projection technique using optical fibre sensors for a tomography system. From the dynamic experiment of solid/gas flow using plastic beads in a gravity flow rig, the designed optical fibre sensors are reliable in measuring the mass flow rate below 40% of flow. Another important matter that has been discussed is the image processing rate or IPR. Generally, the applied image reconstruction algorithms, the construction of the sensor and also the designed software are considered to be reliable and suitable to perform real-time image reconstruction and mass flow rate measurements.

  15. Localized measurement of longitudinal and transverse flow velocities in colloidal suspensions using optical coherence tomography

    NARCIS (Netherlands)

    Weiss, N.; Van Leeuwen, T.G.; Kalkman, J.

    2013-01-01

    We report on localized measurement of the longitudinal and transverse flow velocities in a colloidal suspension using optical coherence tomography. We present a model for the path-length resolved autocorrelation function including diffusion and flow, which we experimentally verify. For flow that is

  16. Optical flow based guidance system design for semi-strapdown image homing guided missiles

    Directory of Open Access Journals (Sweden)

    Huang Lan

    2016-10-01

    Full Text Available This paper focuses mainly on semi-strapdown image homing guided (SSIHG system design based on optical flow for a six-degree-of-freedom (6-DOF axial-symmetric skid-to-turn missile. Three optical flow algorithms suitable for large displacements are introduced and compared. The influence of different displacements on computational accuracy of the three algorithms is analyzed statistically. The total optical flow of the SSIHG missile is obtained using the Scale Invariant Feature Transform (SIFT algorithm, which is the best among the three for large displacements. After removing the rotational optical flow caused by rotation of the gimbal and missile body from the total optical flow, the remaining translational optical flow is smoothed via Kalman filtering. The circular navigation guidance (CNG law with impact angle constraint is then obtained utilizing the smoothed translational optical flow and position of the target image. Simulations are carried out under both disturbed and undisturbed conditions, and results indicate the proposed guidance strategy for SSIHG missiles can result in a precise target hit with a desired impact angle without the need for the time-to-go parameter.

  17. Longitudinal optical monitoring of blood flow in breast tumors during neoadjuvant chemotherapy

    Science.gov (United States)

    Cochran, J. M.; Chung, S. H.; Leproux, A.; Baker, W. B.; Busch, D. R.; DeMichele, A. M.; Tchou, J.; Tromberg, B. J.; Yodh, A. G.

    2017-06-01

    We measure tissue blood flow markers in breast tumors during neoadjuvant chemotherapy and investigate their correlation to pathologic complete response in a pilot longitudinal patient study (n  =  4). Tumor blood flow is quantified optically by diffuse correlation spectroscopy (DCS), and tissue optical properties, blood oxygen saturation, and total hemoglobin concentration are derived from concurrent diffuse optical spectroscopic imaging (DOSI). The study represents the first longitudinal DCS measurement of neoadjuvant chemotherapy in humans over the entire course of treatment; it therefore offers a first correlation between DCS flow indices and pathologic complete response. The use of absolute optical properties measured by DOSI facilitates significant improvement of DCS blood flow calculation, which typically assumes optical properties based on literature values. Additionally, the combination of the DCS blood flow index and the tissue oxygen saturation from DOSI permits investigation of tissue oxygen metabolism. Pilot results from four patients suggest that lower blood flow in the lesion-bearing breast is correlated with pathologic complete response. Both absolute lesion blood flow and lesion flow relative to the contralateral breast exhibit potential for characterization of pathological response. This initial demonstration of the combined optical approach for chemotherapy monitoring provides incentive for more comprehensive studies in the future and can help power those investigations.

  18. Horn-Schunck Optical Flow with a Multi-Scale Strategy

    Directory of Open Access Journals (Sweden)

    Enric Meinhardt-Llopis

    2013-07-01

    Full Text Available The seminal work of Horn and Schunck is the first variational method for optical flow estimation. It introduced a novel framework where the optical flow is computed as the solution of a minimization problem. From the assumption that pixel intensities do not change over time, the optical flow constraint equation is derived. This equation relates the optical flow with the derivatives of the image. There are infinitely many vector fields that satisfy the optical flow constraint, thus the problem is ill-posed. To overcome this problem, Horn and Schunck introduced an additional regularity condition that restricts the possible solutions. Their method minimizes both the optical flow constraint and the magnitude of the variations of the flow field, producing smooth vector fields. One of the limitations of this method is that, typically, it can only estimate small motions. In the presence of large displacements, this method fails when the gradient of the image is not smooth enough. In this work, we describe an implementation of the original Horn and Schunck method and also introduce a multi-scale strategy in order to deal with larger displacements. For this multi-scale strategy, we create a pyramidal structure of downsampled images and change the optical flow constraint equation with a nonlinear formulation. In order to tackle this nonlinear formula, we linearize it and solve the method iteratively in each scale. In this sense, there are two common approaches: one approach that computes the motion increment in the iterations; or the one we follow, that computes the full flow during the iterations. The solutions are incrementally refined over the scales. This pyramidal structure is a standard tool in many optical flow methods.

  19. A Line Search Multilevel Truncated Newton Algorithm for Computing the Optical Flow

    Directory of Open Access Journals (Sweden)

    Lluís Garrido

    2015-06-01

    Full Text Available We describe the implementation details and give the experimental results of three optimization algorithms for dense optical flow computation. In particular, using a line search strategy, we evaluate the performance of the unilevel truncated Newton method (LSTN, a multiresolution truncated Newton (MR/LSTN and a full multigrid truncated Newton (FMG/LSTN. We use three image sequences and four models of optical flow for performance evaluation. The FMG/LSTN algorithm is shown to lead to better optical flow estimation with less computational work than both the LSTN and MR/LSTN algorithms.

  20. Real-time optical flow estimation on a GPU for a skied-steered mobile robot

    Science.gov (United States)

    Kniaz, V. V.

    2016-04-01

    Accurate egomotion estimation is required for mobile robot navigation. Often the egomotion is estimated using optical flow algorithms. For an accurate estimation of optical flow most of modern algorithms require high memory resources and processor speed. However simple single-board computers that control the motion of the robot usually do not provide such resources. On the other hand, most of modern single-board computers are equipped with an embedded GPU that could be used in parallel with a CPU to improve the performance of the optical flow estimation algorithm. This paper presents a new Z-flow algorithm for efficient computation of an optical flow using an embedded GPU. The algorithm is based on the phase correlation optical flow estimation and provide a real-time performance on a low cost embedded GPU. The layered optical flow model is used. Layer segmentation is performed using graph-cut algorithm with a time derivative based energy function. Such approach makes the algorithm both fast and robust in low light and low texture conditions. The algorithm implementation for a Raspberry Pi Model B computer is discussed. For evaluation of the algorithm the computer was mounted on a Hercules mobile skied-steered robot equipped with a monocular camera. The evaluation was performed using a hardware-in-the-loop simulation and experiments with Hercules mobile robot. Also the algorithm was evaluated using KITTY Optical Flow 2015 dataset. The resulting endpoint error of the optical flow calculated with the developed algorithm was low enough for navigation of the robot along the desired trajectory.

  1. Single- and Two-Phase Flow Characterization Using Optical Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Virgínia H.V. Baroncini

    2015-03-01

    Full Text Available Single- and two-phase flow characterization using optical fiber Bragg gratings (FBGs is presented. The sensor unit consists of the optical fiber Bragg grating positioned transversely to the flow and fixed in the pipe walls. The hydrodynamic pressure applied by the liquid or air/liquid flow to the optical fiber induces deformation that can be detected by the FBG. Given that the applied pressure is directly related to the mass flow, it is possible to establish a relationship using the grating resonance wavelength shift to determine the mass flow when the flow velocity is well known. For two phase flows of air and liquid, there is a significant change in the force applied to the fiber that accounts for the very distinct densities of these substances. As a consequence, the optical fiber deformation and the correspondent grating wavelength shift as a function of the flow will be very different for an air bubble or a liquid slug, allowing their detection as they flow through the pipe. A quasi-distributed sensing tool with 18 sensors evenly spread along the pipe is developed and characterized, making possible the characterization of the flow, as well as the tracking of the bubbles over a large section of the test bed. Results show good agreement with standard measurement methods and open up plenty of opportunities to both laboratory measurement tools and field applications.

  2. Application of low-coherence optical fiber Doppler anemometry to fluid-flow measurement: optical system considerations

    Science.gov (United States)

    Boyle, William J. O.; Grattan, Kenneth T. V.; Palmer, Andrew W.; Meggitt, B. T.

    1991-08-01

    A fiber optic Doppler anemometric (FODA) sensor using an optical delay cavity technique and having the advantage of detecting velocity rather than simple speed is outlined. In this sensor the delay in a sensor cavity formed from light back-reflected from a fiber tip (Fresnel reflection) and light back-reflected from particles flowing in a fluid is balanced by the optical delay when light from this sensor cavity passes through a reference cavity formed by a combination of the zero and first diffraction orders produced by a Bragg cell inserted into the optical arrangement. The performance of an experimental sensor based on this scheme is investigated, and velocity measurements using the Doppler shift data from moving objects are presented. The sensitivity of the scheme is discussed, with reference to the other techniques of fluid flow measurement.

  3. Fabrication of rigid and flexible refractive-index-matched flow phantoms for flow visualisation and optical flow measurements

    Science.gov (United States)

    Geoghegan, P. H.; Buchmann, N. A.; Spence, C. J. T.; Moore, S.; Jermy, M.

    2012-05-01

    A method for the construction of both rigid and compliant (flexible) transparent flow phantoms of biological flow structures, suitable for PIV and other optical flow methods with refractive-index-matched working fluid is described in detail. Methods for matching the in vivo compliance and elastic wave propagation wavelength are presented. The manipulation of MRI and CT scan data through an investment casting mould is described. A method for the casting of bubble-free phantoms in silicone elastomer is given. The method is applied to fabricate flexible phantoms of the carotid artery (with and without stenosis), the carotid artery bifurcation (idealised and patient-specific) and the human upper airway (nasal cavity). The fidelity of the phantoms to the original scan data is measured, and it is shown that the cross-sectional error is less than 5% for phantoms of simple shape but up to 16% for complex cross-sectional shapes such as the nasal cavity. This error is mainly due to the application of a PVA coating to the inner mould and can be reduced by shrinking the digital model. Sixteen per cent variation in area is less than the natural patient to patient variation of the physiological geometries. The compliance of the phantom walls is controlled within physiologically realistic ranges, by choice of the wall thickness, transmural pressure and Young's modulus of the elastomer. Data for the dependence of Young's modulus on curing temperature are given for Sylgard 184. Data for the temperature dependence of density, viscosity and refractive index of the refractive-index-matched working liquid (i.e. water-glycerol mixtures) are also presented.

  4. Mapping the spatiotemporal dynamics of calcium signaling in cellular neural networks using optical flow

    CERN Document Server

    Buibas, Marius; Nizar, Krystal; Silva, Gabriel A

    2009-01-01

    An optical flow gradient algorithm was applied to spontaneously forming networks of neurons and glia in culture imaged by fluorescence optical microscopy in order to map functional calcium signaling with single pixel resolution. Optical flow estimates the direction and speed of motion of objects in an image between subsequent frames in a recorded digital sequence of images (i.e. a movie). Computed vector field outputs by the algorithm were able to track the spatiotemporal dynamics of calcium signaling patterns. We begin by briefly reviewing the mathematics of the optical flow algorithm, describe how to solve for the displacement vectors, and how to measure their reliability. We then compare computed flow vectors with manually estimated vectors for the progression of a calcium signal recorded from representative astrocyte cultures. Finally, we applied the algorithm to preparations of primary astrocytes and hippocampal neurons and to the rMC-1 Muller glial cell line in order to illustrate the capability of the ...

  5. Fiber Optic Mass Flow Gauge for Liquid Cryogenic Fuel Facilities Monitoring and Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I proposal describes a fiber optic mass flow gauge that will aid in managing liquid hydrogen and oxygen fuel storage and transport. The increasing...

  6. Myocardial Motion Estimation: An Evaluation of Optical Flow Computation Techniques on Echocardiographic Images

    Directory of Open Access Journals (Sweden)

    Slamet Riyadi

    2011-01-01

    Full Text Available The use of image processing technique for cardiac motion analysis has been an active research in the past decade. The estimation of myocardial motion eases the cardiologist in diagnosing cardiac abnormalities. In term of movement analysis, optical flow is the most popular technique that has been used by researchers. This paper describes the implementation and evaluation of three optical flow computation techniques to estimate the myocardial motion using echocardiographic images. The three techniquesare the global smoothness method (GSM, the local smoothness method (LSM and warping technique (WT. Optical flow field is computed based on healthy cardiac video on parasternal short axes view. These techniques look promising since the optical flow fields can be utilized to estimate the myocardial movement and comply with its true movement. The performances of each technique in terms of the direction, homogeneity and computing time, are also discussed.

  7. Estimation of Centers and Stagnation points in optical flow fields

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1997-01-01

    In a topological sense fluid flows are characterised by their stagnation points. Given a temporal sequence of images of fluids we will consider the application of local polynomials to the estimation of smooth fluid flow fields. The normal flow at intensity contours is estimated from the local...... distribution of spatio-temporal energy, which is sampled using a set of spatio-temporal quadrature filters. These observations of normal flows are then integrated into smooth flow fields by locally approximating first order polynomials in the spatial coordinates to the flow vectors. This technique furthermore...... allows us to give a qualitative local description of the flow field and to estimate the position of stagnation points (e.g. nodes, saddles, and centers). We will apply the algorithm to two data sets. The first sequence consists of infrared images from the meteorological satellite Meteosat. Here...

  8. A Theory for Optical Flow-based Transport on Image Manifolds

    Science.gov (United States)

    2011-11-21

    I2(x, y) = I1(x+ vx(x, y), y + vy(x, y)). (2) A common assumption in computing the optical flow between images is bright- ness constancy [16], where...not be the transport operator of choice, since such manifolds do not in general obey the brightness constancy requirement needed in optical flow...on Comp. Vision, 2010. [15] M. I. Miller , L. Younes, Group actions, homeomorphisms, and matching: a general framework, Intl. J. of Comp. Vision 41 (1

  9. Optical contouring of an acrylic surface for non-intrusive diagnostics in pipe-flow investigations

    Science.gov (United States)

    de Witt, Benjamin J.; Coronado-Diaz, Haydee; Hugo, Ronald J.

    2008-07-01

    In this work, an acrylic surface was optically contoured to correct for the optical distortion caused by a transparent pipe wall. This method can be applied to non-invasive viewing/imaging techniques for fluid flow experiments. Software tools were developed to aid in the design of an optically contoured acrylic test section for pipe-flow experiments. Numerical models were computed for a standard acrylic pipe, inner diameter 57.15 mm, with water enclosed. An optical contour prototype was machined on a 5-axis CNC machine, and polished with 1-15 μm diamond paste, alleviating any surface imperfections without significantly altering the contoured surface. Experiments were then performed to measure the emerging optical wavefront and was found to emerge planar when utilizing the optical contour. It was determined that the wavefront was corrected to within ten wavelengths of a Helium-Neon (He-Ne) laser beam.

  10. Development of fiber optic sensor for fluid flow of astronauts’ life-support system

    Science.gov (United States)

    Shachneva, E. A.; Murashkina, T. I.

    2016-08-01

    This paper proposes a fiber optic sensor consumption (volume, speed) of liquids in life-support systems of astronauts, as well as offers a simple method and apparatus for reproducing the parameters of fluid flow needed in research, yustiovke and adjusting the optical sensor system.

  11. Application of Optical Flow Sensors for Dead Reckoning, Heading Reference, Obstacle Detection, and Obstacle Avoidance

    Science.gov (United States)

    2015-09-01

    OPTICAL FLOW SENSORS FOR DEAD RECKONING, HEADING REFERENCE, OBSTACLE DETECTION, AND OBSTACLE AVOIDANCE by Tarek M. Nejah September 2015... SENSORS FOR DEAD RECKONING, HEADING REFERENCE, OBSTACLE DETECTION, AND OBSTACLE AVOIDANCE 5. FUNDING NUMBERS 6. AUTHOR(S) Nejah, Tarek M. 7...avoidance using only one optical mouse sensor was presented in this thesis. Odometry, position tracking, and obstacle avoidance are important issues in

  12. Dynamics of Zonal Flows: Failure of Wave-Kinetic Theory, and New Geometrical Optics Approximations

    CERN Document Server

    Parker, Jeffrey B

    2016-01-01

    The self-organization of turbulence into regular zonal flows can be fruitfully investigated with quasilinear methods and statistical descriptions. A wave kinetic equation that assumes asymptotically large-scale zonal flows is pathological. From an exact description of quasilinear dynamics emerges two better geometrical optics approximations. These involve not only the mean flow shear but also the second and third derivative of the mean flow. One approximation takes the form of a new wave kinetic equation, but is only valid when the zonal flow is quasi-static and wave action is conserved.

  13. Children's Brain Responses to Optic Flow Vary by Pattern Type and Motion Speed.

    Directory of Open Access Journals (Sweden)

    Rick O Gilmore

    Full Text Available Structured patterns of global visual motion called optic flow provide crucial information about an observer's speed and direction of self-motion and about the geometry of the environment. Brain and behavioral responses to optic flow undergo considerable postnatal maturation, but relatively little brain imaging evidence describes the time course of development in motion processing systems in early to middle childhood, a time when psychophysical data suggest that there are changes in sensitivity. To fill this gap, electroencephalographic (EEG responses were recorded in 4- to 8-year-old children who viewed three time-varying optic flow patterns (translation, rotation, and radial expansion/contraction at three different speeds (2, 4, and 8 deg/s. Modulations of global motion coherence evoked coherent EEG responses at the first harmonic that differed by flow pattern and responses at the third harmonic and dot update rate that varied by speed. Pattern-related responses clustered over right lateral channels while speed-related responses clustered over midline channels. Both children and adults show widespread responses to modulations of motion coherence at the second harmonic that are not selective for pattern or speed. The results suggest that the developing brain segregates the processing of optic flow pattern from speed and that an adult-like pattern of neural responses to optic flow has begun to emerge by early to middle childhood.

  14. Optic flow-based collision-free strategies: From insects to robots.

    Science.gov (United States)

    Serres, Julien R; Ruffier, Franck

    2017-09-01

    Flying insects are able to fly smartly in an unpredictable environment. It has been found that flying insects have smart neurons inside their tiny brains that are sensitive to visual motion also called optic flow. Consequently, flying insects rely mainly on visual motion during their flight maneuvers such as: takeoff or landing, terrain following, tunnel crossing, lateral and frontal obstacle avoidance, and adjusting flight speed in a cluttered environment. Optic flow can be defined as the vector field of the apparent motion of objects, surfaces, and edges in a visual scene generated by the relative motion between an observer (an eye or a camera) and the scene. Translational optic flow is particularly interesting for short-range navigation because it depends on the ratio between (i) the relative linear speed of the visual scene with respect to the observer and (ii) the distance of the observer from obstacles in the surrounding environment without any direct measurement of either speed or distance. In flying insects, roll stabilization reflex and yaw saccades attenuate any rotation at the eye level in roll and yaw respectively (i.e. to cancel any rotational optic flow) in order to ensure pure translational optic flow between two successive saccades. Our survey focuses on feedback-loops which use the translational optic flow that insects employ for collision-free navigation. Optic flow is likely, over the next decade to be one of the most important visual cues that can explain flying insects' behaviors for short-range navigation maneuvers in complex tunnels. Conversely, the biorobotic approach can therefore help to develop innovative flight control systems for flying robots with the aim of mimicking flying insects' abilities and better understanding their flight. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Fast optical measurements and imaging of flow mixing

    DEFF Research Database (Denmark)

    Clausen, Sønnik; Fateev, Alexander; Nielsen, Karsten Lindorff

    in combustion enhancement can be also obtained. The infrared camera was also used together with special endoscope optics for fast thermal imaging of a coal-straw flame in an industrial boiler. Obtained time-resolved infrared images provided useful information for the diagnostics of the flame and fuel...

  16. Optic flow estimation on trajectories generated by bio-inspired closed-loop flight.

    Science.gov (United States)

    Shoemaker, Patrick A; Hyslop, Andrew M; Humbert, J Sean

    2011-05-01

    We generated panoramic imagery by simulating a fly-like robot carrying an imaging sensor, moving in free flight through a virtual arena bounded by walls, and containing obstructions. Flight was conducted under closed-loop control by a bio-inspired algorithm for visual guidance with feedback signals corresponding to the true optic flow that would be induced on an imager (computed by known kinematics and position of the robot relative to the environment). The robot had dynamics representative of a housefly-sized organism, although simplified to two-degree-of-freedom flight to generate uniaxial (azimuthal) optic flow on the retina in the plane of travel. Surfaces in the environment contained images of natural and man-made scenes that were captured by the moving sensor. Two bio-inspired motion detection algorithms and two computational optic flow estimation algorithms were applied to sequences of image data, and their performance as optic flow estimators was evaluated by estimating the mutual information between outputs and true optic flow in an equatorial section of the visual field. Mutual information for individual estimators at particular locations within the visual field was surprisingly low (less than 1 bit in all cases) and considerably poorer for the bio-inspired algorithms that the man-made computational algorithms. However, mutual information between weighted sums of these signals and comparable sums of the true optic flow showed significant increases for the bio-inspired algorithms, whereas such improvement did not occur for the computational algorithms. Such summation is representative of the spatial integration performed by wide-field motion-sensitive neurons in the third optic ganglia of flies.

  17. Flow measurements in micro holes with electrochemical and optical methods

    Energy Technology Data Exchange (ETDEWEB)

    Zosel, J.; Guth, U.; Thies, A.; Reents, B

    2003-09-30

    The decreasing feature size of electronic compounds down to the micrometer range is paralleled by an increase in the aspect ratio, worsening all mass transport related processes. In this paper the conditions of liquid flow into micro holes and blind micro vias (BMV) with diameter of 100-300 {mu}m and depth between 100 {mu}m and 1.5 mm are investigated. The flow was induced by surface directed jet flows, visualised by microscopy aided particle image velocimetry ({mu}-PIV) and correlated with electrochemical mass transfer measurements using the ferro/ferri-hexacyanide redox couple. It was found that the mean flow velocity in the holes and the penetration depth in the blind holes are influenced especially by the roughness of the inner walls and, at a lower scale, by the velocity and the impinging angle of the jet. The results enable the estimation of the mean flow rate in through holes and the penetration depth in BMV at defined hydrodynamic conditions in the bath. This is one of the preconditions for the appropriate engineering of plating lines designed for micro structures.

  18. An optical fiber Fabry-Perot flow measurement technology based on partial bend structure

    Science.gov (United States)

    Yang, Huijia; Jiang, Junfeng; Zhang, Xuezhi; Pan, Yuheng; Zhu, Wanshan; Zhou, Xiang; Liu, Tiegen

    2016-08-01

    An optical fiber Fabry-Perot (F-P) flow measurement technology is presented, which is based on partial bend structure. A 90° partial bend structure is designed to achieve the non-probe flow measurement with a pressure difference. The fluid simulation results of partial bend structure show that the error of the pressure difference is below 0.05 kPa during steady flow. The optical fiber F-P sensor mounted on the elbow with pressure test accuracy of 1% full scale is used to measure the fluid flow. Flow test results show that when the flow varies from 1 m3/h to 6.5 m3/h at ambient temperature of 25 °C, the response time is 1 s and the flow test accuracy is 4.5% of the F-P flow test system, proving that the F-P flow test method based on partial bend structure can be used in fluid flow measurement.

  19. Velocity fields and optical turbulence near the boundary in a strongly convective laboratory flow

    Science.gov (United States)

    Matt, Silvia; Hou, Weilin; Goode, Wesley; Hellman, Samuel

    2016-05-01

    Boundary layers around moving underwater vehicles or other platforms can be a limiting factor for optical communication. Turbulence in the boundary layer of a body moving through a stratified medium can lead to small variations in the index of refraction, which impede optical signals. As a first step towards investigating this boundary layer effect on underwater optics, we study the flow near the boundary in the Rayleigh-Bénard laboratory tank at the Naval Research Laboratory Stennis Space Center. The tank is set up to generate temperature-driven, i.e., convective turbulence, and allows control of the turbulence intensity. This controlled turbulence environment is complemented by computational fluid dynamics simulations to visualize and quantify multi-scale flow patterns. The boundary layer dynamics in the laboratory tank are quantified using a state-of-the-art Particle Image Velocimetry (PIV) system to examine the boundary layer velocities and turbulence parameters. The velocity fields and flow dynamics from the PIV are compared to the numerical model and show the model to accurately reproduce the velocity range and flow dynamics. The temperature variations and thus optical turbulence effects can then be inferred from the model temperature data. Optical turbulence is also visible in the raw data from the PIV system. The newly collected data are consistent with previously reported measurements from high-resolution Acoustic Doppler Velocimeter profilers (Nortek Vectrino), as well as fast thermistor probes and novel next-generation fiber-optics temperature sensors. This multi-level approach to studying optical turbulence near a boundary, combining in-situ measurements, optical techniques, and numerical simulations, can provide new insight and aid in mitigating turbulence impacts on underwater optical signal transmission.

  20. Optical studies of shock generated transient supersonic base flows

    Science.gov (United States)

    Liang, P.-Y.; Bershader, D.; Wray, A.

    1982-01-01

    A shock tube employing interferometric and schlieren techniques is used to study transient base flow phenomena following shock wave passage over two plane bluff bodies: a hemicircular cylinder and a cylinder with the Galileo Jovian probe profile. An attempt is made to understand the physics of transition from transient to steady state flow, and to provide code verification for a study employing the Illiac IV computer. Transient base flow interactions include a series of shock diffraction, regular, and Mach reflections, coupled with boundary layer development, separation, and recompression. Vorticity generation and transport underlie these features. The quantitative verification of the computer code includes comparisons of transient pressure and density fields, near wake geometries, and bow shock standoff distances.

  1. Obstacle detection and terrain characterization using optical flow without 3-D reconstruction

    Science.gov (United States)

    Young, Gin-Shu; Hong, Tsai Hong; Herman, Martin; Yang, Jackson C. S.

    1992-11-01

    For many applications in computer vision, it is important to recover range, 3-D motion, and/or scene geometry from a sequence of images. However, there are many robot behaviors which can be achieved by extracting relevant 2-D information from the imagery and using this information directly, without recovery of such information. In this paper, we focus on two behaviors, obstacle avoidance and terrain navigation. A novel method of these two behaviors has been developed without 3-D reconstruction. This approach is often called purposive active vision. A linear relationship, plotted as a line and called a reference flow line, has been found. The difference between a plotted line and the reference flow line can be used to detect discrete obstacles above or below the reference terrain. For terrain characterization, slopes of surface regions can be calculated directly from optical flow. Some error analysis is also done. The main features of this approach are that (1) discrete obstacles are detected directly from 2-D optical flow, no 3-D reconstruction is performed; (2) terrain slopes are also calculated from 2- D optical flow; (3) knowledge about the terrain model, camera-to-ground coordinate transformation, or vehicle (or camera) motion is not required; (4) the error sources involved are reduced to a minimum, since the only information required is a component of optical flow. An initial experiment using noisy synthetic data is also included to demonstrate the applicability and robustness of the method.

  2. High speed optical holography of retinal blood flow

    CERN Document Server

    Pellizzari, Mathilde; Degardin, Julie; Sahel, Jose-Alain; Fink, Mathias; Paques, Michel; Atlan, Michael

    2016-01-01

    We performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms.

  3. TV-L1 optical flow for vector valued images

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau; Roholm, Lars; Nielsen, Mads

    2011-01-01

    a generalized algorithm that works on vector valued images, by means of a generalized projection step. We give examples of calculations of flows for a number of multi- dimensional constancy assumptions, e.g. gradient and RGB, and show how the developed methodology expands to any kind of vector valued images....... The resulting algorithms have the same degree of parallelism as the case of one-dimensional images, and we have produced an efficient GPU implementation, that can take vector valued images with vectors of any dimension. Finally we demonstrate how these algorithms generally produce better flows than the original...

  4. Optical measurement of a micro coriolis mass flow sensor

    NARCIS (Netherlands)

    Kristiansen, L.; Mehendale, A.; Brouwer, D.M.; Zwikker, J.M.; Klein, M.E.

    2009-01-01

    Haneveld [1,2] demonstrated a micro Coriolis mass flow sensor, operating in the measurement range of 0 to 1 g/hr achieving a resolution in the order of 10 mg/hr using a laser vibrometer. Equipped with an integrated capacitive [3] readout the measurement uncertainty amounted to 2% of the full scale r

  5. Optic flow based station-keeping and wind rejection for small flying vehicles

    Science.gov (United States)

    Patrick, Bryan

    Optic flow and Wide Field Integration (WFI) have shown potential for application to autonomous navigation of Unmanned Air Vehicles (UAVs). In this study the application of these same methods to other tasks, namely station-keeping and wind rejection, is examined. Theory surrounding optic flow, WFI and wind gust modeling is examined to provide a theoretical background. A controller based on a Hinfinity bounded formulation of the well known Linear Quadratic Regulator in designed to both mitigate wind disturbances and station-keep. The performance of this controller is assessed via simulation to determine both performance and trade-offs in implementation such as the method for optic flow calculation. Furthermore, flight tests are performed to examine the real world effectiveness of the controller. Finally, conclusions about potential improvement to implementation are drawn

  6. The electronic image stabilization technology research based on improved optical-flow motion vector estimation

    Science.gov (United States)

    Wang, Chao; Ji, Ming; Zhang, Ying; Jiang, Wentao; Lu, Xiaoyan; Wang, Jiaoying; Yang, Heng

    2016-01-01

    The electronic image stabilization technology based on improved optical-flow motion vector estimation technique can effectively improve the non normal shift, such as jitter, rotation and so on. Firstly, the ORB features are extracted from the image, a set of regions are built on these features; Secondly, the optical-flow vector is computed in the feature regions, in order to reduce the computational complexity, the multi resolution strategy of Pyramid is used to calculate the motion vector of the frame; Finally, qualitative and quantitative analysis of the effect of the algorithm is carried out. The results show that the proposed algorithm has better stability compared with image stabilization based on the traditional optical-flow motion vector estimation method.

  7. On the stability of multicast flow aggregation in IP over optical network for IPTV delivery

    Institute of Scientific and Technical Information of China (English)

    Xuan Luo; Yaohui Jin; Qingji Zeng; Weiqiang Sun; Wei Guo; Weisheng Hu

    2008-01-01

    The stable multicast flow aggregation (MFA) problem in internet protocol (IP) over optical network under the dynamical scenario is studied. Given an optical network topology, there is a set of head ends and access routers attached to the optical network, in which each head end can provide a set of programs (IP multicasting flows) and each access router requests a set of programs, we find a set of stable light-trees to accommodate the optimally aggregated multicast IP flows if the requests of access routers changed dynamically. We introduce a program correlation matrix to describe the preference of end users' requests. As the original MFA problem is NP-complete, a heuristic approach, named most correlated program first (MCPF), is presented and compared with the extended least tree first (ELTF) algorithm which is topologyaware. Simulation results show that MCPF can achieve better performance than ELTF in terms of stability with negligible increment of network resource usage.

  8. Measuring In-Plane Micro-Motion of Micro-Structure Using Optical Flow

    Institute of Scientific and Technical Information of China (English)

    JIN Cuiyun; JIN Shijiu; LI Dachao; WANG Jianlin

    2009-01-01

    Optical flow method is one of the most important methods of analyzing motion images.Optical flow field is used to analyze characteristics of motion objects.According to motion features of micro-electronic mechanical system(MEMS)micro-structure,the optical algorithm based on label field and neighborhood optimization is presented to analyze the in-plane micro-motion of micro-structure.Firstly,high speed motion states for each frequency segment of micro-structure in cyclic motion are frozen based on stroboscopic principle.Thus a series of image sequences,and can obtain reliable and precise optical field and reduce computing time.As micro-resonator of urement precision of the presented algorithm is high,and measurement repeatability reaches 40 am under the same experiment condition.

  9. Encoding of naturalistic optic flow by motion sensitive neurons of nucleus rotundus in the zebra finch (Taeniopygia guttata.

    Directory of Open Access Journals (Sweden)

    Dennis eEckmeier

    2013-09-01

    Full Text Available The retinal image changes that occur during locomotion, the optic flow, carry information about self-motion and the three-dimensional structure of the environment. Especially fast moving animals with only little binocular vision depend on these depth cues for manoeuvring. They actively control their gaze to facilitate perception of depth based on cues in the optic flow. In the visual system of birds, nucleus rotundus neurons were originally found to respond to object motion but not to background motion. However, when background and object were both moving, responses increase the more the direction and velocity of object and background motion on the retina differed. These properties may play a role in representing depth cues in the optic flow. We therefore investigated how neurons in nucleus rotundus respond to optic flow that contains depth cues. We presented simplified and naturalistic optic flow on a panoramic LED display while recording from single neurons in nucleus rotundus of anaesthetized zebra finches. Unlike most studies on motion vision in birds, our stimuli included depth information.We found extensive responses of motion selective neurons in nucleus rotundus to optic flow stimuli. Simplified stimuli revealed preferences for optic flow reflecting translational or rotational self-motion. Naturalistic optic flow stimuli elicited complex response modulations, but the presence of objects was signalled by only few neurons. The neurons that did respond to objects in the optic flow, however, show interesting properties.

  10. Optical flows method for lightweight agile remote sensor design and instrumentation

    Science.gov (United States)

    Wang, Chong; Xing, Fei; Wang, Hongjian; You, Zheng

    2013-08-01

    Lightweight agile remote sensors have become one type of the most important payloads and were widely utilized in space reconnaissance and resource survey. These imaging sensors are designed to obtain the high spatial, temporary and spectral resolution imageries. Key techniques in instrumentation include flexible maneuvering, advanced imaging control algorithms and integrative measuring techniques, which are closely correlative or even acting as the bottle-necks for each other. Therefore, mutual restrictive problems must be solved and optimized. Optical flow is the critical model which to be fully represented in the information transferring as well as radiation energy flowing in dynamic imaging. For agile sensors, especially with wide-field-of view, imaging optical flows may distort and deviate seriously when they perform large angle attitude maneuvering imaging. The phenomena are mainly attributed to the geometrical characteristics of the three-dimensional earth surface as well as the coupled effects due to the complicated relative motion between the sensor and scene. Under this circumstance, velocity fields distribute nonlinearly, the imageries may badly be smeared or probably the geometrical structures are changed since the image velocity matching errors are not having been eliminated perfectly. In this paper, precise imaging optical flow model is established for agile remote sensors, for which optical flows evolving is factorized by two forms, which respectively due to translational movement and image shape changing. Moreover, base on that, agile remote sensors instrumentation was investigated. The main techniques which concern optical flow modeling include integrative design with lightweight star sensors along with micro inertial measurement units and corresponding data fusion, the assemblies of focal plane layout and control, imageries post processing for agile remote sensors etc. Some experiments show that the optical analyzing method is effective to

  11. Motion Detection for PC based on Security System by using Optical Flow

    Directory of Open Access Journals (Sweden)

    K. Hawari Ghazali

    2012-01-01

    Full Text Available This system is designed aims to detect and analyze the motion of people that have been recorded on PC, which response rapidly to the abnormal motion based on  optical flow method. Horn-Schunck technique  is one of optical flow method which has ability to detect the motion in image sequences by examining the velocities of the motion objects. It will response to abnormal motion and triggered the alarm in order to alert the people beware to their surroundings.

  12. High speed optical holography of retinal blood flow.

    Science.gov (United States)

    Pellizzari, M; Simonutti, M; Degardin, J; Sahel, J-A; Fink, M; Paques, M; Atlan, M

    2016-08-01

    We performed noninvasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (∼30 microns diameter) over 400×400  pixels with a spatial resolution of ∼8 microns and a temporal resolution of ∼6.5  ms.

  13. Optical Measurements in Non-Equilibrium Plasmas and Flows

    Science.gov (United States)

    2009-09-01

    Communications, Vol. 35, p. 69 (1979). 12. D.A. McQuarrie and J.D Simon, “Physical Chemistry – A Molecular Approach,” University Science Books... chemistry , shock structure, and heat transfer in the complex flow field around hypervelocity vehicles. The acceleration of low temperature oxidation...equation (2), B12 is the Einstein B coefficient for stimulated absorption, N1 is the number density of absorbers in the lower quantum state (rotational

  14. Maximum Likelihood Estimation of Monocular Optical Flow Field for Mobile Robot Ego-motion

    Directory of Open Access Journals (Sweden)

    Huajun Liu

    2016-01-01

    Full Text Available This paper presents an optimized scheme of monocular ego-motion estimation to provide location and pose information for mobile robots with one fixed camera. First, a multi-scale hyper-complex wavelet phase-derived optical flow is applied to estimate micro motion of image blocks. Optical flow computation overcomes the difficulties of unreliable feature selection and feature matching of outdoor scenes; at the same time, the multi-scale strategy overcomes the problem of road surface self-similarity and local occlusions. Secondly, a support probability of flow vector is defined to evaluate the validity of the candidate image motions, and a Maximum Likelihood Estimation (MLE optical flow model is constructed based not only on image motion residuals but also their distribution of inliers and outliers, together with their support probabilities, to evaluate a given transform. This yields an optimized estimation of inlier parts of optical flow. Thirdly, a sampling and consensus strategy is designed to estimate the ego-motion parameters. Our model and algorithms are tested on real datasets collected from an intelligent vehicle. The experimental results demonstrate the estimated ego-motion parameters closely follow the GPS/INS ground truth in complex outdoor road scenarios.

  15. Steering behaviour can be modulated by different optic flows during walking.

    Science.gov (United States)

    Sarre, Guillaume; Berard, Jessica; Fung, Joyce; Lamontagne, Anouk

    2008-05-01

    Optic flow is a typical pattern of visual motion that can be used to control locomotion. While the ability to discriminate translational or rotational optic flows have been extensively studied, how these flows control steering during locomotion is not known. The goal of this study was to compare the steering behaviour of subjects subjected to rotational, translational, or combined (rotational added to translational) optic flows with a focus of expansion (FOE) located to the right, left, or straight ahead. Ten healthy young subjects were instructed to walk straight in a virtual room viewed through a helmet mounted display while the location of the FOE was randomly offset. Horizontal trajectory of the body's centre of mass (CoM), as well as rotations of the head, trunk and foot were recorded in coordinates of both the physical and virtual worlds. Results show that subjects experienced a mediolateral shift in CoM opposite to the FOE location, with larger corrections being observed at more eccentric FOE locations. Head and body segment reorientations were only observed for optic flows containing a rotational component. CoM trajectory corrections in the physical world were also of small magnitude, leading to deviation errors in the virtual world. Altogether, these results suggest a profound influence of vision, especially due to the pattern of visual motion, on steering behaviours during locomotion.

  16. Optical PIV and LDV Comparisons of Internal Flow Investigations in SHF Impeller

    Directory of Open Access Journals (Sweden)

    G. Wuibaut

    2006-01-01

    Full Text Available The paper presents a comparison between two sets of experimental results in a centrifugal flow pump. The tested impeller is the so-called SHF impeller for which many experimental data have been continuously produced to built databases for CFD code validations with various levels of approximation. Measurements have been performed using optical techniques: 2D particle image velocimetry (PIV technique on an air test model and 2D laser doppler velocimetry (LDV technique on a water model, both for different flow rates. For the present study, results obtained by these optical techniques are compared together in terms of phase averaged velocity and velocity fluctuations inside the impeller flow passage for design flow rate.

  17. Optical Feedback Interferometry for Velocity Measurement of Parallel Liquid-Liquid Flows in a Microchannel

    Directory of Open Access Journals (Sweden)

    Evelio E. Ramírez-Miquet

    2016-08-01

    Full Text Available Optical feedback interferometry (OFI is a compact sensing technique with recent implementation for flow measurements in microchannels. We propose implementing OFI for the analysis at the microscale of multiphase flows starting with the case of parallel flows of two immiscible fluids. The velocity profiles in each phase were measured and the interface location estimated for several operating conditions. To the authors knowledge, this sensing technique is applied here for the first time to multiphase flows. Theoretical profiles issued from a model based on the Couette viscous flow approximation reproduce fairly well the experimental results. The sensing system and the analysis presented here provide a new tool for studying more complex interactions between immiscible fluids (such as liquid droplets flowing in a microchannel.

  18. Wavefront sensors for optical diagnostics in fluid mechanics: Application to heated flow, turbulence and droplet evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Neal, D.R.; O`Hern, T.J.; Torczynski, J.R.; Warren, M.E.; Shul, R. [Sandia National Labs., Albuquerque, NM (United States); McKechnie, T.S. [POD Associates, Inc., Albuquerque, NM (United States)

    1993-09-01

    Optical measurement techniques are extremely useful in fluid mechanics because of their non-invasive nature. However, it is often difficult to separate measurement effects due to pressure, temperature and density in real flows. Using a variation of a Shack-Hartmann wavefront sensor, we have made density measurements that have extremely large dynamic range coupled with excellent sensitivity at high temporal and spatial resolution. We have examined several classes of flow including volumetrically heated gas, turbulence and droplet evaporation.

  19. Flow-induced birefringence: the hidden PSF killer in high performance injection-molded plastic optics

    Science.gov (United States)

    Chidley, Matthew D.; Tkaczyk, Tomasz; Kester, Robert; Descour, Michael R.

    2006-02-01

    A 7-mm OD, NA = 1 water immersion injection-molded plastic endoscope objective has been fabricated for a laser scanning fiber confocal reflectance microscope (FCRM) system specifically designed for in vivo detection of cervical and oral pre-cancers. Injection-molded optics was selected for the ability to incorporate aspheric surfaces into the optical design and its high volume capabilities. Our goal is high performance disposable endoscope probes. This objective has been built and tested as a stand-alone optical system, a Strehl ratio greater than 0.6 has been obtained. One of the limiting factors of optical performance is believed to be flow-induced birefringence. We have investigated different configurations for birefringence visualization and believe the circular polariscope is most useful for inspection of injection-molded plastic optics. In an effort to decrease birefringence effects, two experiments were conducted. They included: (1) annealing of the optics after fabrication and (2) modifying the injection molding prameters (packing pressures, injection rates, and hold time). While the second technique showed improvement, the annealing process could not improve quality without physically warping the lenses. Therefore, to effectively reduce flow-induced birefringence, molding conditions have to be carefully selected. These parameters are strongly connected to the physical part geometry. Both optical design and fabrication technology have to be considered together to deliver low birefringence while maintaining the required manufacturing tolerances. In this paper we present some of our current results that illustrate how flow-induced birefringence can degrade high performance injection-molded plastic optical systems.

  20. Flow-dependent double-nanohole optical trapping of 20 nm polystyrene nanospheres

    Science.gov (United States)

    Zehtabi-Oskuie, Ana; Bergeron, Jarrah Gerald; Gordon, Reuven

    2012-01-01

    We study the influence of fluid flow on the ability to trap optically a 20 nm polystyrene particle from a stationary microfluidic environment and then hold it against flow. Increased laser power is required to hold nanoparticles as the flow rate is increased, with an empirical linear dependence of 1 μl/(min×mW). This is promising for the delivery of additional nanoparticles to interact with a trapped nanoparticle; for example, to study protein-protein interactions, and for the ability to move the trapped particle in solution from one location to another. PMID:23236587

  1. Experimental verification of the frozen flow atmospheric turbulence assumption with use of astronomical adaptive optics telemetry.

    Science.gov (United States)

    Poyneer, Lisa; van Dam, Marcos; Véran, Jean-Pierre

    2009-04-01

    We use closed-loop deformable mirror telemetry from Altair and Keck adaptive optics (AO) to determine whether atmospheric turbulence follows the frozen flow hypothesis. Using telemetry from AO systems, our algorithms (based on the predictive Fourier control framework) detect frozen flow >94% of the time. Usually one to three layers are detected. Between 20% and 40% of the total controllable phase power is due to frozen flow. Velocity vector RMS variability is less than 0.5 m/s (per axis) on 10-s intervals, indicating that the atmosphere is stable enough for predictive control to measure and adapt to prevailing atmospheric conditions before they change.

  2. Effective star tracking method based on optical flow analysis for star trackers.

    Science.gov (United States)

    Sun, Ting; Xing, Fei; Wang, Xiaochu; Li, Jin; Wei, Minsong; You, Zheng

    2016-12-20

    Benefiting from rapid development of imaging sensor technology, modern optical technology, and a high-speed computing chip, the star tracker's accuracy, dynamic performance, and update rate have been greatly improved with low power consumption and miniature size. The star tracker is currently one of the most competitive attitude measurement sensors. However, due to restrictions of the optical imaging system, difficulties still exist in moving star spot detection and star tracking when in special motion conditions. An effective star tracking method based on optical flow analysis for star trackers is proposed in this paper. Spot-based optical flow, based on a gray gradient between two adjacent star images, is analyzed to distinguish the star spot region and obtain an accurate star spot position so that the star tracking can keep continuous under high dynamic conditions. The obtained star vectors and extended Kalman filter (EKF) are then combined to conduct an angular velocity estimation to ensure region prediction of the star spot; this can be combined with the optical flow analysis result. Experiment results show that the method proposed in this paper has advantages in conditions of large angular velocity and large angular acceleration, despite the presence of noise. Higher functional density and better performance can be achieved; thus, the star tracker can be more widely applied in small satellites, remote sensing, and other complex space missions.

  3. Time-of-Travel Methods for Measuring Optical Flow on Board a Micro Flying Robot

    Directory of Open Access Journals (Sweden)

    Erik Vanhoutte

    2017-03-01

    Full Text Available For use in autonomous micro air vehicles, visual sensors must not only be small, lightweight and insensitive to light variations; on-board autopilots also require fast and accurate optical flow measurements over a wide range of speeds. Using an auto-adaptive bio-inspired Michaelis–Menten Auto-adaptive Pixel (M 2 APix analog silicon retina, in this article, we present comparative tests of two optical flow calculation algorithms operating under lighting conditions from 6 × 10 − 7 to 1 . 6 × 10 − 2 W·cm − 2 (i.e., from 0.2 to 12,000 lux for human vision. Contrast “time of travel” between two adjacent light-sensitive pixels was determined by thresholding and by cross-correlating the two pixels’ signals, with measurement frequency up to 5 kHz for the 10 local motion sensors of the M 2 APix sensor. While both algorithms adequately measured optical flow between 25 ∘ /s and 1000 ∘ /s, thresholding gave rise to a lower precision, especially due to a larger number of outliers at higher speeds. Compared to thresholding, cross-correlation also allowed for a higher rate of optical flow output (99 Hz and 1195 Hz, respectively but required substantially more computational resources.

  4. Adaptive guided image filter for warping in variational optical flow computation

    NARCIS (Netherlands)

    Tu, Z.; Poppe, R.W.; Veltkamp, R.C.

    2016-01-01

    The variational optical flow method is considered to be the standard method to calculate an accurate dense motion field between successive frames. It assumes that the energy function has spatiotemporal continuities and appearance motions are small. However, for real image sequences, the temporal con

  5. Convergence of Object Focused Simultaneous Estimation of Optical Flow and State Dynamics

    Directory of Open Access Journals (Sweden)

    Nicholas Bauer

    2014-10-01

    Full Text Available The purpose of this study is to prove the convergence of the simultaneous estimation of the optical flow and object state (SEOS method. The SEOS method utilizes dynamic object parameter information when calculating optical flow in tracking a moving object within a video stream. Optical flow estimation for the SEOS method requires the minimization of an error function containing the object's physical parameter data. When this function is discretized, the Euler-Lagrange equations form a system of linear equations. The system is arranged such that its property matrix is positive definite symmetric, proving the convergence of the Gauss-Seidel iterative methods. The system of linear equations produced by SEOS can alternatively be resolved by Jacobi iterative schemes. The positive definite symmetric property is not sufficient for Jacobi convergence. The convergence of SEOS for a block diagonal Jacobi is proved by analysing the Euclidean norm of the Jacobi matrix. In this paper, we also investigate the use of SEOS for tracking individual objects within a video sequence. The illustrations provided show the effectiveness of SEOS for localizing objects within a video sequence and generating optical flow results.

  6. Moving object localization using optical flow for pedestrian detection from a moving vehicle.

    Science.gov (United States)

    Hariyono, Joko; Hoang, Van-Dung; Jo, Kang-Hyun

    2014-01-01

    This paper presents a pedestrian detection method from a moving vehicle using optical flows and histogram of oriented gradients (HOG). A moving object is extracted from the relative motion by segmenting the region representing the same optical flows after compensating the egomotion of the camera. To obtain the optical flow, two consecutive images are divided into grid cells 14 × 14 pixels; then each cell is tracked in the current frame to find corresponding cell in the next frame. Using at least three corresponding cells, affine transformation is performed according to each corresponding cell in the consecutive images, so that conformed optical flows are extracted. The regions of moving object are detected as transformed objects, which are different from the previously registered background. Morphological process is applied to get the candidate human regions. In order to recognize the object, the HOG features are extracted on the candidate region and classified using linear support vector machine (SVM). The HOG feature vectors are used as input of linear SVM to classify the given input into pedestrian/nonpedestrian. The proposed method was tested in a moving vehicle and also confirmed through experiments using pedestrian dataset. It shows a significant improvement compared with original HOG using ETHZ pedestrian dataset.

  7. Stereoscopic advantages for vection induced by radial, circular, and spiral optic flows.

    Science.gov (United States)

    Palmisano, Stephen; Summersby, Stephanie; Davies, Rodney G; Kim, Juno

    2016-11-01

    Although observer motions project different patterns of optic flow to our left and right eyes, there has been surprisingly little research into potential stereoscopic contributions to self-motion perception. This study investigated whether visually induced illusory self-motion (i.e., vection) is influenced by the addition of consistent stereoscopic information to radial, circular, and spiral (i.e., combined radial + circular) patterns of optic flow. Stereoscopic vection advantages were found for radial and spiral (but not circular) flows when monocular motion signals were strong. Under these conditions, stereoscopic benefits were greater for spiral flow than for radial flow. These effects can be explained by differences in the motion aftereffects generated by these displays, which suggest that the circular motion component in spiral flow selectively reduced adaptation to stereoscopic motion-in-depth. Stereoscopic vection advantages were not observed for circular flow when monocular motion signals were strong, but emerged when monocular motion signals were weakened. These findings show that stereoscopic information can contribute to visual self-motion perception in multiple ways.

  8. Simplified Monolithic Flow Cytometer Chip With Three-Dimensional Hydrodyanmic Focusing And Integrated Fiber-Free Optics

    DEFF Research Database (Denmark)

    Motosuke, Masahiro; Jensen, Thomas Glasdam; Zhuang, Guisheng

    2011-01-01

    A miniaturized flow cytometry incorporating both fluidic and optical systems has a great possibility for portable biochemical sensing or point-of-care diagnostics. This paper presents a simple microfluidic flow cytometer combining reliable 3D hydrodynamic focusing and optical detection without op...... to be applied as a portable platform of cytometer chip....

  9. A semitransparency-based optical-flow method with a point trajectory model for particle-like video.

    Science.gov (United States)

    Sakaino, Hidetomo

    2012-02-01

    This paper proposes a new semitransparency-based optical-flow model with a point trajectory (PT) model for particle-like video. Previous optical-flow models have used ranging from image brightness constancy to image brightness change models as constraints. However, two important issues remain unsolved. The first is how to track/match a semitransparent object with a very large displacement between frames. Such moving objects with different shapes and sizes in an outdoor scene move against a complicated background. Second, due to semitransparency, the image intensity between frames can also violate a previous image brightness-based optical-flow model. Thus, we propose a two-step optimization for the optical-flow estimation model for a moving semitransparent object, i.e., particle. In the first step, a rough optical flow between particles is estimated by a new alpha constancy constraint that is based on an image generation model of semitransparency. In the second step, the optical flow of a particle with a continuous trajectory in a definite temporal interval based on a PT model can be refined. Many experiments using various falling-snow and foggy scenes with multiple moving vehicles show the significant improvement of the optical flow compared with a previous optical-flow model.

  10. Application of double-layered skin phantoms for optical flow imaging during laser tattoo treatments

    Science.gov (United States)

    Lee, Byeong-il; Song, Woosub; Kim, Hyejin; Kang, Hyun Wook

    2016-05-01

    The feasible application of double-layered skin phantoms was evaluated to identify artificial blood flow with a Doppler optical coherence tomography (DOCT) system for laser tattoo treatments. Polydimethylsiloxane (PDMS) was used to fabricate the artificial phantoms with flow channels embedded. A double-integrating sphere system with an inverse adding-doubling method quantified both the absorption and the reduced scattering coefficients for epidermis and dermis phantoms. Both OCT and caliper measurements confirmed the double-layered phantom structure (epidermis = 136 ± 17 µm vs. dermis = 3.0 ± 0.1 mm). The DOCT method demonstrated that high flow rates were associated with high image contrast, visualizing the position and the shape of the flow channel. Application of the channel-embedded skin phantoms in conjunction with DOCT can be a reliable technique to assess dynamic variations in the blood flow during and after laser tattoo treatments.

  11. Simultaneous measurement of localized diffusion and flow using optical coherence tomography

    CERN Document Server

    Weiss, Nicolás; Kalkman, Jeroen

    2014-01-01

    We report on the simultaneous and localized measurements of the diffusion coefficient and flow velocity based on the normalized autocorrelation function using optical coherence tomography (OCT). Our results on a flowing solution of polystyrene spheres show that the flow velocity and the diffusion coefficient can be reliably estimated in a regime determined by the sample diffusivity, the local flow velocity, and the Gaussian beam waist. We experimentally show that a smaller beam waist results in an improvement of the velocity sensitivity at cost of the precision and accuracy of the estimation of the diffusion coefficient. Further, we show that the decay of the OCT autocorrelation due to flow depends only on the Gaussian beam waist irrespective of the sample position with respect to the focus position.

  12. Bayesian modeling of perceived surface slant from actively-generated and passively-observed optic flow.

    Directory of Open Access Journals (Sweden)

    Corrado Caudek

    Full Text Available We measured perceived depth from the optic flow (a when showing a stationary physical or virtual object to observers who moved their head at a normal or slower speed, and (b when simulating the same optic flow on a computer and presenting it to stationary observers. Our results show that perceived surface slant is systematically distorted, for both the active and the passive viewing of physical or virtual surfaces. These distortions are modulated by head translation speed, with perceived slant increasing directly with the local velocity gradient of the optic flow. This empirical result allows us to determine the relative merits of two alternative approaches aimed at explaining perceived surface slant in active vision: an "inverse optics" model that takes head motion information into account, and a probabilistic model that ignores extra-retinal signals. We compare these two approaches within the framework of the bayesian theory. The "inverse optics" bayesian model produces veridical slant estimates if the optic flow and the head translation velocity are measured with no error; because of the influence of a "prior" for flatness, the slant estimates become systematically biased as the measurement errors increase. The bayesian model, which ignores the observer's motion, always produces distorted estimates of surface slant. Interestingly, the predictions of this second model, not those of the first one, are consistent with our empirical findings. The present results suggest that (a in active vision perceived surface slant may be the product of probabilistic processes which do not guarantee the correct solution, and (b extra-retinal signals may be mainly used for a better measurement of retinal information.

  13. Evaluation of optical flow algorithms for tracking endocardial surfaces on three-dimensional ultrasound data

    Science.gov (United States)

    Duan, Qi; Angelini, Elsa D.; Herz, Susan L.; Ingrassia, Christopher M.; Gerard, Olivier; Costa, Kevin D.; Holmes, Jeffrey W.; Laine, Andrew F.

    2005-04-01

    With relatively high frame rates and the ability to acquire volume data sets with a stationary transducer, 3D ultrasound systems, based on matrix phased array transducers, provide valuable three-dimensional information, from which quantitative measures of cardiac function can be extracted. Such analyses require segmentation and visual tracking of the left ventricular endocardial border. Due to the large size of the volumetric data sets, manual tracing of the endocardial border is tedious and impractical for clinical applications. Therefore the development of automatic methods for tracking three-dimensional endocardial motion is essential. In this study, we evaluate a four-dimensional optical flow motion tracking algorithm to determine its capability to follow the endocardial border in three dimensional ultrasound data through time. The four-dimensional optical flow method was implemented using three-dimensional correlation. We tested the algorithm on an experimental open-chest dog data set and a clinical data set acquired with a Philips' iE33 three-dimensional ultrasound machine. Initialized with left ventricular endocardial data points obtained from manual tracing at end-diastole, the algorithm automatically tracked these points frame by frame through the whole cardiac cycle. A finite element surface was fitted through the data points obtained by both optical flow tracking and manual tracing by an experienced observer for quantitative comparison of the results. Parameterization of the finite element surfaces was performed and maps displaying relative differences between the manual and semi-automatic methods were compared. The results showed good consistency between manual tracing and optical flow estimation on 73% of the entire surface with fewer than 10% difference. In addition, the optical flow motion tracking algorithm greatly reduced processing time (about 94% reduction compared to human involvement per cardiac cycle) for analyzing cardiac function in three

  14. Honeybees' speed depends on dorsal as well as lateral, ventral and frontal optic flows.

    Directory of Open Access Journals (Sweden)

    Geoffrey Portelli

    Full Text Available Flying insects use the optic flow to navigate safely in unfamiliar environments, especially by adjusting their speed and their clearance from surrounding objects. It has not yet been established, however, which specific parts of the optical flow field insects use to control their speed. With a view to answering this question, freely flying honeybees were trained to fly along a specially designed tunnel including two successive tapering parts: the first part was tapered in the vertical plane and the second one, in the horizontal plane. The honeybees were found to adjust their speed on the basis of the optic flow they perceived not only in the lateral and ventral parts of their visual field, but also in the dorsal part. More specifically, the honeybees' speed varied monotonically, depending on the minimum cross-section of the tunnel, regardless of whether the narrowing occurred in the horizontal or vertical plane. The honeybees' speed decreased or increased whenever the minimum cross-section decreased or increased. In other words, the larger sum of the two opposite optic flows in the horizontal and vertical planes was kept practically constant thanks to the speed control performed by the honeybees upon encountering a narrowing of the tunnel. The previously described ALIS ("AutopiLot using an Insect-based vision System" model nicely matches the present behavioral findings. The ALIS model is based on a feedback control scheme that explains how honeybees may keep their speed proportional to the minimum local cross-section of a tunnel, based solely on optic flow processing, without any need for speedometers or rangefinders. The present behavioral findings suggest how flying insects may succeed in adjusting their speed in their complex foraging environments, while at the same time adjusting their distance not only from lateral and ventral objects but also from those located in their dorsal visual field.

  15. Effect of the modulation of optic flow speed on gait parameters in children with hemiplegic cerebral palsy.

    Science.gov (United States)

    Lim, Hyungwon

    2014-01-01

    [Purpose] We investigated the effects of modulation of the optic flow speed on gait parameters in children with hemiplegic cerebral palsy. [Methods] We examined 10 children with hemiplegic cerebral palsy. The children underwent gait analysis under 3 different conditions of optic flow speed: slow, normal, and fast optic flow speed. The children walked across the walkway of a GAITRite system, while watching a virtual reality screen, and walking velocity, cadence, stride length, step length, single support time, and double support time were recorded. [Results] Compared with the other applied flow speed conditions, the fast optic flow speed (2 times the normal speed) significantly increased walking velocity, cadence, normalized step length, base of support, and single support cycle of both the paretic and non-paretic lower limbs. Moreover, compared with the other applied flow speed conditions, the slow optic flow speed (0.25 times the normal speed) yielded a significantly decreased walking velocity, cadence, normalized step length, base of support, and single support cycle for both the paretic and non-paretic lower limbs. [Conclusion] The gait parameters of children with hemiplegic cerebral palsy are altered by modulation of the optic flow speed. Thus, we believe that gait training involving modulation of the optic flow speed is feasible and suitable for resolving abnormal gait patterns in children with hemiplegic cerebral palsy.

  16. Non-Linear Optical Flow Cytometry Using a Scanned, Bessel Beam Light-Sheet

    Science.gov (United States)

    Collier, Bradley B.; Awasthi, Samir; Lieu, Deborah K.; Chan, James W.

    2015-01-01

    Modern flow cytometry instruments have become vital tools for high-throughput analysis of single cells. However, as issues with the cellular labeling techniques often used in flow cytometry have become more of a concern, the development of label-free modalities for cellular analysis is increasingly desired. Non-linear optical phenomena (NLO) are of growing interest for label-free analysis because of the ability to measure the intrinsic optical response of biomolecules found in cells. We demonstrate that a light-sheet consisting of a scanned Bessel beam is an optimal excitation geometry for efficiently generating NLO signals in a microfluidic environment. The balance of photon density and cross-sectional area provided by the light-sheet allowed significantly larger two-photon fluorescence intensities to be measured in a model polystyrene microparticle system compared to measurements made using other excitation focal geometries, including a relaxed Gaussian excitation beam often used in conventional flow cytometers. PMID:26021750

  17. Flow rate estimation by optical coherence tomography using contrast dilution approach

    Science.gov (United States)

    Štohanzlová, Petra; Kolář, Radim

    2015-07-01

    This paper describes experiments and methodology for flow rate estimation using optical coherence tomography and dilution method in single fiber setup. The single fiber is created from custom made glass capillary and polypropylene hollow fiber. As a data source, measurements on single fiber phantom with continuous flow of carrier medium and bolus of Intralipid solution as a contrast agent were used using Thorlabs OCT OCS1300SS. The measured data were processed by methods of image processing, in order to precisely align the individual images in the sequence and extract dilution curves from the area inside the fiber. An experiment proved that optical coherence tomography can be used for flow rate estimation by the dilution method with precision around 7%.

  18. Influence of prolonged optic flow stimuli on spontaneous activities of cat PMLS neurons

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Changes in neuronal spontaneous activities after prolonged optic flow stimulation (using the three basic flow modes: translation, radiation and rotation) were investigated by extracellular single-unit recording in cortical area PMLS of the cat. The results showed that the evoked responses decreased with the prolongation of visual stimuli, and the spontaneous activities usually dropped to a lower level after the stimuli were withdrawn. Generally, the reduction in spontaneous activities was larger after adaptation in the preferred direction than in the non-preferred direction. This difference was much pronounced to translation stimuli, but relatively insignificant to radiation and rotation. These points suggest that non-specific fatigue may act as the key factor in adaptation to simple translation, while some kinds of more complicated, direction-specific mechanism may be involved in adaptation to the complex optic flow patterns. In addition, PMLS may play an important role in perception and adaptation to complex motion and the relevant motion after-effects.

  19. Optical Measurement of Mass Flow of a Two-Phase Fluid

    Science.gov (United States)

    Wiley, John; Pedersen, Kevin; Koman, Valentin; Gregory, Don

    2008-01-01

    An optoelectronic system utilizes wavelength-dependent scattering of light for measuring the density and mass flow of a two-phase fluid in a pipe. The apparatus was invented for original use in measuring the mass flow of a two-phase cryogenic fluid (e.g., liquid hydrogen containing bubbles of hydrogen gas), but underlying principles of operation can readily be adapted to non-cryogenic two-phase fluids. The system (see figure) includes a laser module, which contains two or more laser diodes, each operating at a different wavelength. The laser module also contains beam splitters that combine the beams at the various wavelengths so as to produce two output beams, each containing all of the wavelengths. One of the multiwavelength output beams is sent, via a multimode fiberoptic cable, to a transmitting optical coupler. The other multiwavelength output beam is sent, via another multimode fiber-optic cable, to a reference detector module, wherein fiber-optic splitters split the light into several multiwavelength beams, each going to a photodiode having a spectral response that is known and that differs from the spectral responses of the other photodiodes. The outputs of these photodiodes are digitized and fed to a processor, which executes an algorithm that utilizes the known spectral responses to convert the photodiode outputs to obtain reference laser-power levels for the various wavelengths. The transmitting optical coupler is mounted in (and sealed to) a hole in the pipe and is oriented at a slant with respect to the axis of the pipe. The transmitting optical coupler contains a collimating lens and a cylindrical lens that form the light emerging from the end of the fiber-optic cable into a fan-shaped beam in a meridional plane of the pipe. Receiving optical couplers similar to the transmitting optical couplers are mounted in the same meridional plane at various longitudinal positions on the opposite side of the pipe, approximately facing the transmitting optical

  20. Optical Study of Flow and Combustion in an HCCI Engine with Negative Valve Overlap

    Science.gov (United States)

    Wilson, Trevor S.; Xu, Hongming; Richardson, Steve; Wyszynski, Miroslaw L.; Megaritis, Thanos

    2006-07-01

    One of the most widely used methods to enable Homogeneous Charge Compression Ignition (HCCI) combustion is using negative valve overlapping to trap a sufficient quantity of hot residual gas. The characteristics of air motion with specially designed valve events having reduced valve lift and durations associated with HCCI engines and their effect on subsequent combustion are not yet fully understood. In addition, the ignition process and combustion development in such engines are very different from those in conventional spark-ignition or diesel compression ignition engines. Very little data has been reported concerning optical diagnostics of the flow and combustion in the engine using negative valve overlapping. This paper presents an experimental investigation into the in-cylinder flow characteristics and combustion development in an optical engine operating in HCCI combustion mode. PIV measurements have been taken under motored engine conditions to provide a quantitative flow characterisation of negative valve overlap in-cylinder flows. The ignition and combustion process was imaged using a high resolution charge coupled device (CCD) camera and the combustion imaging data was supplemented by simultaneously recorded in-cylinder pressure data which assisted the analysis of the images. It is found that the flow characteristics with negative valve overlapping are less stable and more valve event driven than typical spark ignition in-cylinder flows, while the combustion initiation locations are not uniformly distributed.

  1. Processing of Egomotion-Consistent Optic Flow in the Rhesus Macaque Cortex.

    Science.gov (United States)

    Cottereau, Benoit R; Smith, Andrew T; Rima, Samy; Fize, Denis; Héjja-Brichard, Yseult; Renaud, Luc; Lejards, Camille; Vayssière, Nathalie; Trotter, Yves; Durand, Jean-Baptiste

    2017-01-01

    The cortical network that processes visual cues to self-motion was characterized with functional magnetic resonance imaging in 3 awake behaving macaques. The experimental protocol was similar to previous human studies in which the responses to a single large optic flow patch were contrasted with responses to an array of 9 similar flow patches. This distinguishes cortical regions where neurons respond to flow in their receptive fields regardless of surrounding motion from those that are sensitive to whether the overall image arises from self-motion. In all 3 animals, significant selectivity for egomotion-consistent flow was found in several areas previously associated with optic flow processing, and notably dorsal middle superior temporal area, ventral intra-parietal area, and VPS. It was also seen in areas 7a (Opt), STPm, FEFsem, FEFsac and in a region of the cingulate sulcus that may be homologous with human area CSv. Selectivity for egomotion-compatible flow was never total but was particularly strong in VPS and putative macaque CSv. Direct comparison of results with the equivalent human studies reveals several commonalities but also some differences.

  2. Calibration and deployment of a fiber-optic sensing system for monitoring debris flows.

    Science.gov (United States)

    Huang, Ching-Jer; Chu, Chung-Ray; Tien, Tsung-Mo; Yin, Hsiao-Yuen; Chen, Ping-Sen

    2012-01-01

    This work presents a novel fiber-optic sensing system, capable of monitoring debris flows or other natural hazards that produce ground vibrations. The proposed sensing system comprises a demodulator (BraggSCOPE, FS5500), which includes a broadband light source and a data logger, a four-port coupler and four Fiber Bragg Grating (FBG) accelerometers. Based on field tests, the performance of the proposed fiber-optic sensing system is compared with that of a conventional sensing system that includes a geophone or a microphone. Following confirmation of the reliability of the proposed sensing system, the fiber-optic sensing systems are deployed along the Ai-Yu-Zi and Chu-Shui Creeks in Nautou County of central Taiwan for monitoring debris flows. Sensitivity test of the deployed fiber-optic sensing system along the creek banks is also performed. Analysis results of the seismic data recorded by the systems reveal in detail the frequency characteristics of the artificially generated ground vibrations. Results of this study demonstrate that the proposed fiber-optic sensing system is highly promising for use in monitoring natural disasters that generate ground vibrations.

  3. Theoretical and Experimental Study on Wide Range Optical Fiber Turbine Flow Sensor.

    Science.gov (United States)

    Du, Yuhuan; Guo, Yingqing

    2016-07-15

    In this paper, a novel fiber turbine flow sensor was proposed and demonstrated for liquid measurement with optical fiber, using light intensity modulation to measure the turbine rotational speed for converting to flow rate. The double-circle-coaxial (DCC) fiber probe was introduced in frequency measurement for the first time. Through the divided ratio of two rings light intensity, the interference in light signals acquisition can be eliminated. To predict the characteristics between the output frequency and flow in the nonlinear range, the turbine flow sensor model was built. Via analyzing the characteristics of turbine flow sensor, piecewise linear equations were achieved in expanding the flow measurement range. Furthermore, the experimental verification was tested. The results showed that the flow range ratio of DN20 turbine flow sensor was improved 2.9 times after using piecewise linear in the nonlinear range. Therefore, combining the DCC fiber sensor and piecewise linear method, it can be developed into a strong anti-electromagnetic interference(anti-EMI) and wide range fiber turbine flowmeter.

  4. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

    Science.gov (United States)

    Jiang, Xu; Wang, Keda; Li, Junqing; Zhan, Hui; Song, Zhenan; Che, Guohang; Lyu, Guohui

    2017-01-01

    This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE) light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed. PMID:28212268

  5. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2017-02-01

    Full Text Available This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed.

  6. Density and Cavitating Flow Results from a Full-Scale Optical Multiphase Cryogenic Flowmeter

    Science.gov (United States)

    Korman, Valentin

    2007-01-01

    Liquid propulsion systems are hampered by poor flow measurements. The measurement of flow directly impacts safe motor operations, performance parameters as well as providing feedback from ground testing and developmental work. NASA Marshall Space Flight Center, in an effort to improve propulsion sensor technology, has developed an all optical flow meter that directly measures the density of the fluid. The full-scale sensor was tested in a transient, multiphase liquid nitrogen fluid environment. Comparison with traditional density models shows excellent agreement with fluid density with an error of approximately 0.8%. Further evaluation shows the sensor is able to detect cavitation or bubbles in the flow stream and separate out their resulting effects in fluid density.

  7. Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously

    Science.gov (United States)

    Guo, Li; Shi, Rui; Zhang, Chao; Zhu, Dan; Ding, Zhihua; Li, Peng

    2016-08-01

    Tissue optical clearing (TOC) is helpful for reducing scattering and enhancing the penetration depth of light, and shows promising potential in optimizing optical imaging performances. A mixture of fructose with PEG-400 and thiazone (FPT) is used as an optical clearing agent in mouse dorsal skin and evaluated with OCT angiography (Angio-OCT) by quantifying optical properties and blood flow imaging simultaneously. It is observed that FPT leads to an improved imaging performance for the deeper tissues. The imaging performance improvement is most likely caused by the FPT-induced dehydration of skin, and the reduction of scattering coefficient (more than ˜40.5%) and refractive-index mismatching (more than ˜25.3%) in the superficial (epidermal, dermal, and hypodermal) layers. A high correlation (up to ˜90%) between the relative changes in refractive-index mismatching and Angio-OCT signal strength is measured. The optical clearing rate is ˜5.83×10-5 cm/s. In addition, Angio-OCT demonstrates enhanced performance in imaging cutaneous hemodynamics with satisfactory spatiotemporal resolution and contrast when combined with TOC, which exhibits a powerful practical application in studying microcirculation.

  8. Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM).

    Science.gov (United States)

    Tang, Anson H L; Lai, Queenie T K; Chung, Bob M F; Lee, Kelvin C M; Mok, Aaron T Y; Yip, G K; Shum, Anderson H C; Wong, Kenneth K Y; Tsia, Kevin K

    2017-06-28

    Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture - information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization

  9. Total retinal blood flow and reproducibility evaluation by three beam optical Doppler tomography

    Science.gov (United States)

    Haindl, Richard; Trasischker, Wolfgang; Wartak, Andreas; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K.

    2016-03-01

    We present a three beam optical Doppler tomography (ODT) technique suitable for 3-D velocity and flow measurements to evaluate total retinal blood circulation from and to the optic nerve head (ONH). The system consists of three independent ODT channels. Superluminescent diodes with a central wavelength of 840 nm and a spectral bandwidth of 50 nm were used. The sources are coupled to collimators resting in a specially designed mount to ensure a well-defined beam geometry, necessary for the full reconstruction of the three dimensional velocity vector. The reconstruction works without prior knowledge on the vessel geometry, which is normally required for ODT systems with less than three beams. The beams share a common bulk optics Michelson interferometer, while the detection comprises three identical spectrometers with a line scan rate of 50 kHz. 20 eyes of healthy volunteers were imaged with the 3 beam ODT, employing a circular scan pattern around the ONH. The mean total blood flow was calculated for arteries (47.1 +/- 2.4 μl/min (mean +/- SD)) and veins (47.1 +/- 2.7 μl/min μl/min) independently. The two results showed no significant difference (paired t-test, p < 0.96), rendering both equally reliable for total flow measurements. Furthermore the reproducibility of the method was evaluated for the total flow and flow, velocities within each individual vessel of 6 eyes. The average variation for total flow measurements is sufficiently low to detect deviations of ~ 6% indicating high precision of the proposed method.

  10. Fiber optic flow velocity sensor based on an in-fiber integrated Michelson interferometer

    Science.gov (United States)

    Yuan, Libo; Yang, Jun; Liu, Zhihai

    2008-04-01

    A novel fiber optic flow velocity sensor based on a twin-core fiber Michelson interferometer has been proposed and demonstrated. The sensor only is a segment of twin-core fiber acting as cylinder cantilever beam. The force exerted on the cylinder by the flow of a fluid with unknown velocity bends the fiber, which corresponding to the shift of the phase of the twin-core in-fiber integrated Michelson interferometer. This twin-core fiber sensing technique could automatically compensate the variation of environmental temperature and pressure due to both arms of the interferometer would be affected equally by such changes.

  11. Analysis of spectrum characteristics of optical scintillation in stack gas flow

    Institute of Scientific and Technical Information of China (English)

    Liu Wen-Qing; Liu He-Lai; Zeng Zong-Yong; Jiang Yu

    2006-01-01

    Based on the analysis of spectrum characteristics of intensity fluctuations while light beams pass through stack gas flow in an industrial setting, this paper puts emphasis upon discussing the spectrum of optical intensity fluctuations by the variety of particle concentration in stack gas flow. This paper also gives the primary theoretical explanation of the measurement results in the stack of coal-fired utility boilers. Meanwhile, the cross-correlation formula is given as the theoretical basis of velocity measurement by using particle concentration scintillation.

  12. Microchip Flow Cytometer with Integrated Polymer Optical Elements for Measurement of Scattered Light

    DEFF Research Database (Denmark)

    Wang, Zhenyu; El-Ali, Jamil; Perch-Nielsen, Ivan Ryberg

    2004-01-01

    channels to form a complete microchip flow cytometer. All the optical elements, the microfluidic system, and the fiber-to-waveguide couplers were defined in one layer of polymer (SU-8, negative photoresist) by standard photolithography. With only one single mask procedure, all the fabrication and packaging...... processes can be finished in one day. Polystyrene beads were measured in the microchip flow cytometer, and three signals (forward scattering, large angle scattering and extinction) were measured simultaneously for each bead. The average intensities of the forward Scattered light and the incident light...

  13. A spectral optical flow method for determining velocities from digital imagery

    CERN Document Server

    Hurlburt, Neal

    2015-01-01

    We present a method for determining surface flows from solar images based upon optical flow techniques. We apply the method to sets of images obtained by a variety of solar imagers to assess its performance. The {\\tt opflow3d} procedure is shown to extract accurate velocity estimates when provided perfect test data and quickly generates results consistent with completely distinct methods when applied on global scales. We also validate it in detail by comparing it to an established method when applied to high-resolution datasets and find that it provides comparable results without the need to tune, filter or otherwise preprocess the images before its application.

  14. Minimum cost maximum flow algorithm for upstream bandwidth allocation in OFDMA passive optical networks

    Science.gov (United States)

    Wu, Yating; Kuang, Bin; Wang, Tao; Zhang, Qianwu; Wang, Min

    2015-12-01

    This paper presents a minimum cost maximum flow (MCMF) based upstream bandwidth allocation algorithm, which supports differentiated QoS for orthogonal frequency division multiple access passive optical networks (OFDMA-PONs). We define a utility function as the metric to characterize the satisfaction degree of an ONU on the obtained bandwidth. The bandwidth allocation problem is then formulated as maximizing the sum of the weighted total utility functions of all ONUs. By constructing a flow network graph, we obtain the optimized bandwidth allocation using the MCMF algorithm. Simulation results show that the proposed scheme improves the performance in terms of mean packet delay, packet loss ratio and throughput.

  15. Side Information and Noise Learning for Distributed Video Coding using Optical Flow and Clustering

    DEFF Research Database (Denmark)

    Luong, Huynh Van; Rakêt, Lars Lau; Huang, Xin

    2012-01-01

    Transform Domain Wyner-Ziv (TDWZ) coding and proposes using optical flow to improve side information generation and clustering to improve noise modeling. The optical flow technique is exploited at the decoder side to compensate weaknesses of block based methods, when using motion-compensation to generate......Distributed video coding (DVC) is a coding paradigm which exploits the source statistics at the decoder side to reduce the complexity at the encoder. The coding efficiency of DVC critically depends on the quality of side information generation and accuracy of noise modeling. This paper considers...... side information frames. Clustering is introduced to capture cross band correlation and increase local adaptivity in the noise modeling. This paper also proposes techniques to learn from previously decoded (WZ) frames. Different techniques are combined by calculating a number of candidate soft side...

  16. An optical flow-based state-space model of the vocal folds

    DEFF Research Database (Denmark)

    Granados, Alba; Brunskog, Jonas

    2017-01-01

    . A linear and Gaussian nonstationary state-space model is proposed and thoroughly discussed. The evolution model is based on a self-sustained three-dimensional finite element model of the vocal folds, and the observation model involves a dense optical flow algorithm. The results show that the method is able......High-speed movies of the vocal fold vibration are valuable data to reveal vocal fold features for voice pathology diagnosis. This work presents a suitable Bayesian model and a purely theoretical discussion for further development of a framework for continuum biomechanical features estimation...... to capture different deformation patterns between the computed optical flow and the finite element deformation, controlled by the choice of the model tissue parameters....

  17. Tissue motion tracking at the edges of a radiation treatment field using local optical flow analysis

    Science.gov (United States)

    Teo, P. T.; Pistorius, S.

    2014-03-01

    This paper investigates the feasibility and accuracy of tracking the motion of an intruding organ-at-risk (OAR) at the edges of a treatment field using a local optical flow analysis of electronic portal images. An intruding OAR was simulated by modifying the portal images obtained by irradiating a programmable phantom's lung tumour. A rectangular treatment aperture was assumed and the edges of the beam's eye view (BEV) were partitioned into clusters/grids according to the width of the multi-leaf collimators (MLC). The optical flow velocities were calculated and the motion accuracy in these clusters was analysed. A velocity error of 0.4 ± 1.4 mm/s with a linearity of 1.04 for tracking an object intruding at 10mm/s (max) was obtained.

  18. Quantification of smoothing requirement for 3D optic flow calculation of volumetric images

    DEFF Research Database (Denmark)

    Bab-Hadiashar, Alireza; Tennakoon, Ruwan B.; de Bruijne, Marleen

    2013-01-01

    that a (surprisingly) small amount of local smoothing is required to satisfy both the necessary and sufficient conditions for accurate optic flow estimation. This notion is called 'just enough' smoothing, and its proper implementation has a profound effect on the preservation of local information in processing 3D...... dynamic scans. To demonstrate the effect of 'just enough' smoothing, a robust 3D optic flow method with quantized local smoothing is presented, and the effect of local smoothing on the accuracy of motion estimation in dynamic lung CT images is examined using both synthetic and real image sequences......Complexities of dynamic volumetric imaging challenge the available computer vision techniques on a number of different fronts. This paper examines the relationship between the estimation accuracy and required amount of smoothness for a general solution from a robust statistics perspective. We show...

  19. REAL-TIME FACE RECOGNITION BASED ON OPTICAL FLOW AND HISTOGRAM EQUALIZATION

    Directory of Open Access Journals (Sweden)

    D. Sathish Kumar

    2013-05-01

    Full Text Available Face recognition is one of the intensive areas of research in computer vision and pattern recognition but many of which are focused on recognition of faces under varying facial expressions and pose variation. A constrained optical flow algorithm discussed in this paper, recognizes facial images involving various expressions based on motion vector computation. In this paper, an optical flow computation algorithm which computes the frames of varying facial gestures, and integrating with synthesized image in a probabilistic environment has been proposed. Also Histogram Equalization technique has been used to overcome the effect of illuminations while capturing the input data using camera devices. It also enhances the contrast of the image for better processing. The experimental results confirm that the proposed face recognition system is more robust and recognizes the facial images under varying expressions and pose variations more accurately.

  20. Evaluation of advanced Lukas-Kanade optical flow on thoracic 4D-CT.

    Science.gov (United States)

    Hoog Antink, Christoph Bernhard; Singh, Tarunraj; Singla, Puneet; Podgorsak, Matthew

    2013-08-01

    Extensive use of high frequency imaging in medical applications permit the estimation of velocity fields which corresponds to motion of landmarks in the imaging field. The focus of this work is on the development of a robust local optical flow algorithm for velocity field estimation in medical applications. Local polynomial fits to the medical image intensity-maps are used to generate convolution operators to estimate the spatial gradients. A novel polynomial window function with a compact support is used to differentially weight the optical flow gradient constraints in the region of interest. Tikhonov regularization is exploited to synthesize a well posed optimization problem and to penalize large displacements. The proposed algorithm is tested and validated on benchmark datasets for deformable image registration. The ten datasets include large and small deformations, and illustrate that the proposed algorithm outperforms or is competitive with other algorithms tested on this dataset, when using mean and variance of the displacement error as performance metrics.

  1. On convergence of the Horn and Schunck optical-flow estimation method.

    Science.gov (United States)

    Mitiche, Amar; Mansouri, Abdol-Reza

    2004-06-01

    The purpose of this study is to prove convergence results for the Horn and Schunck optical-flow estimation method. Horn and Schunck stated optical-flow estimation as the minimization of a functional. When discretized, the corresponding Euler-Lagrange equations form a linear system of equations We write explicitly this system and order the equations in such a way that its matrix is symmetric positive definite. This property implies the convergence Gauss-Seidel iterative resolution method, but does not afford a conclusion on the convergence of the Jacobi method. However, we prove directly that this method also converges. We also show that the matrix of the linear system is block tridiagonal. The blockwise iterations corresponding to this block tridiagonal structure converge for both the Jacobi and the Gauss-Seidel methods, and the Gauss-Seidel method is faster than the (sequential) Jacobi method.

  2. Simultaneous PIV and pulsed shadow technique in slug flow: a solution for optical problems

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, S. [Karman Institute for Fluid Dynamics, Chaussee de Waterloo 72, B-1640, Rhode Saint Genese (Belgium); Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto (Portugal); Sousa, R.G.; Pinto, A.M.F.R.; Campos, J.B.L.M. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto (Portugal); Riethmuller, M.L. [Karman Institute for Fluid Dynamics, Chaussee de Waterloo 72, B-1640, Rhode Saint Genese (Belgium)

    2003-12-01

    A recent technique of simultaneous particle image velocimetry (PIV) and pulsed shadow technique (PST) measurements, using only one black and white CCD camera, is successfully applied to the study of slug flow. The experimental facility and the operating principle are described. The technique is applied to study the liquid flow pattern around individual Taylor bubbles rising in an aqueous solution of glycerol with a dynamic viscosity of 113 x 10{sup -3} Pa s. With this technique the optical perturbations found in PIV measurements at the bubble interface are completely solved in the nose and in annular liquid film regions as well as in the rear of the bubble for cases in which the bottom is flat. However, for Taylor bubbles with concave oblate bottoms, some optical distortions appear and are discussed. The measurements achieved a spatial resolution of 0.0022 tube diameters. The results reported show high precision and are in agreement with theoretical and experimental published data. (orig.)

  3. Measurement of cerebral blood flow rate and its relationship with brain function using optical coherence tomography

    Science.gov (United States)

    Liu, Jian; Wang, Yi; Zhao, Yuqian; Dou, Shidan; Ma, Yushu; Ma, Zhenhe

    2016-03-01

    Activity of brain neurons will lead to changes in local blood flow rate (BFR). Thus, it is important to measure the local BFR of cerebral cortex on research of neuron activity in vivo, such as rehabilitation evaluation after stroke, etc. Currently, laser Doppler flowmetry is commonly used for blood flow measurement, however, relatively low resolution limits its application. Optical coherence tomography (OCT) is a powerful noninvasive 3D imaging modality with high temporal and spatial resolutions. Furthermore, OCT can provide flow distribution image by calculating Doppler frequency shift which makes it possible for blood flow rate measurement. In this paper, we applied OCT to measure the blood flow rate of the primary motor cortex in rats. The animal was immobilized and anesthetized with isoflurane, an incision was made along the sagittal suture, and bone was exposed. A skull window was opened on the primary motor cortex. Then, blood flow rate changes in the primary motor cortex were monitored by our homemade spectral domain OCT with a stimulation of the passive movement of the front legs. Finally, we established the relationship between blood flow rate and the test design. The aim is to demonstrate the potential of OCT in the evaluation of cerebral cortex function.

  4. B-spline image model for energy minimization-based optical flow estimation.

    Science.gov (United States)

    Le Besnerais, Guy; Champagnat, Frédéric

    2006-10-01

    Robust estimation of the optical flow is addressed through a multiresolution energy minimization. It involves repeated evaluation of spatial and temporal gradients of image intensity which rely usually on bilinear interpolation and image filtering. We propose to base both computations on a single pyramidal cubic B-spline model of image intensity. We show empirically improvements in convergence speed and estimation error and validate the resulting algorithm on real test sequences.

  5. Octopaminergic modulation of a fly visual motion-sensitive neuron during stimulation with naturalistic optic flow

    Directory of Open Access Journals (Sweden)

    Diana eRien

    2013-10-01

    Full Text Available In a variety of species locomotor activity, like walking or flying, has been demonstrated to alter visual information processing. The neuromodulator octopamine was shown to change the response characteristics of optic-flow processing neurons in the fly’s visual system in a similar way as locomotor activity. This modulation resulted in enhanced neuronal responses, in particular during sustained stimulation with high temporal frequencies, and in shorter latencies of responses to abrupt onsets of pattern motion. These state-dependent changes were interpreted to adjust neuronal tuning to the range of high velocities encountered during locomotion. Here we assess the significance of these changes for the processing of optic flow as experienced during flight. Naturalistic image sequences were reconstructed based on measurements of the head position and gaze direction of Calliphora vicina flying in an arena. We recorded the responses of the V1 neuron during presentation of these image sequences on a panoramic stimulus device (FliMax. Consistent with previous accounts, we found that spontaneous as well as stimulus-induced spike rates were increased by an octopamine agonist and decreased by an antagonist. Moreover, a small but consistent decrease in response latency upon octopaminergic activation was present, which might support fast responses to optic flow cues and limit instabilities during closed-loop optomotor regulation. However, apart from these effects the similarities between the dynamic response properties in the different pharmacologically induced states were surprisingly high, indicating that the processing of naturalistic optic flow is not fundamentally altered by octopaminergic modulation.

  6. Toward optic flow regulation for wall-following and centring behaviours

    OpenAIRE

    Franck Ruffier; Julien Serres; Nicolas Franceschini; Stephane Viollet

    2006-01-01

    In our ongoing project on the autonomous guidance of Micro-Air Vehicles (MAVs) in confined indoor and outdoor environments, we have developed a bio-inspired optic flow based autopilot enabling a hovercraft to travel safely, and avoid the walls of a corridor. The hovercraft is an air vehicle endowed with natural roll and pitch stabilization characteristics, in which planar flight control can be developed conveniently. It travels at a constant ground height (~2mm) and senses the environment by ...

  7. Optical Flow in a Smart Sensor Based on Hybrid Analog-Digital Architecture

    Directory of Open Access Journals (Sweden)

    Pablo Guzmán

    2010-03-01

    Full Text Available The purpose of this study is to develop a motion sensor (delivering optical flow estimations using a platform that includes the sensor itself, focal plane processing resources, and co-processing resources on a general purpose embedded processor. All this is implemented on a single device as a SoC (System-on-a-Chip. Optical flow is the 2-D projection into the camera plane of the 3-D motion information presented at the world scenario. This motion representation is widespread well-known and applied in the science community to solve a wide variety of problems. Most applications based on motion estimation require work in real-time; hence, this restriction must be taken into account. In this paper, we show an efficient approach to estimate the motion velocity vectors with an architecture based on a focal plane processor combined on-chip with a 32 bits NIOS II processor. Our approach relies on the simplification of the original optical flow model and its efficient implementation in a platform that combines an analog (focal-plane and digital (NIOS II processor. The system is fully functional and is organized in different stages where the early processing (focal plane stage is mainly focus to pre-process the input image stream to reduce the computational cost in the post-processing (NIOS II stage. We present the employed co-design techniques and analyze this novel architecture. We evaluate the system’s performance and accuracy with respect to the different proposed approaches described in the literature. We also discuss the advantages of the proposed approach as well as the degree of efficiency which can be obtained from the focal plane processing capabilities of the system. The final outcome is a low cost smart sensor for optical flow computation with real-time performance and reduced power consumption that can be used for very diverse application domains.

  8. Optical flow in a smart sensor based on hybrid analog-digital architecture.

    Science.gov (United States)

    Guzmán, Pablo; Díaz, Javier; Agís, Rodrigo; Ros, Eduardo

    2010-01-01

    The purpose of this study is to develop a motion sensor (delivering optical flow estimations) using a platform that includes the sensor itself, focal plane processing resources, and co-processing resources on a general purpose embedded processor. All this is implemented on a single device as a SoC (System-on-a-Chip). Optical flow is the 2-D projection into the camera plane of the 3-D motion information presented at the world scenario. This motion representation is widespread well-known and applied in the science community to solve a wide variety of problems. Most applications based on motion estimation require work in real-time; hence, this restriction must be taken into account. In this paper, we show an efficient approach to estimate the motion velocity vectors with an architecture based on a focal plane processor combined on-chip with a 32 bits NIOS II processor. Our approach relies on the simplification of the original optical flow model and its efficient implementation in a platform that combines an analog (focal-plane) and digital (NIOS II) processor. The system is fully functional and is organized in different stages where the early processing (focal plane) stage is mainly focus to pre-process the input image stream to reduce the computational cost in the post-processing (NIOS II) stage. We present the employed co-design techniques and analyze this novel architecture. We evaluate the system's performance and accuracy with respect to the different proposed approaches described in the literature. We also discuss the advantages of the proposed approach as well as the degree of efficiency which can be obtained from the focal plane processing capabilities of the system. The final outcome is a low cost smart sensor for optical flow computation with real-time performance and reduced power consumption that can be used for very diverse application domains.

  9. Monocular distance estimation with optical flow maneuvers and efference copies: a stability-based strategy.

    Science.gov (United States)

    de Croon, Guido C H E

    2016-01-07

    The visual cue of optical flow plays an important role in the navigation of flying insects, and is increasingly studied for use by small flying robots as well. A major problem is that successful optical flow control seems to require distance estimates, while optical flow is known to provide only the ratio of velocity to distance. In this article, a novel, stability-based strategy is proposed for monocular distance estimation, relying on optical flow maneuvers and knowledge of the control inputs (efference copies). It is shown analytically that given a fixed control gain, the stability of a constant divergence control loop only depends on the distance to the approached surface. At close distances, the control loop starts to exhibit self-induced oscillations. The robot can detect these oscillations and hence be aware of the distance to the surface. The proposed stability-based strategy for estimating distances has two main attractive characteristics. First, self-induced oscillations can be detected robustly by the robot and are hardly influenced by wind. Second, the distance can be estimated during a zero divergence maneuver, i.e., around hover. The stability-based strategy is implemented and tested both in simulation and on board a Parrot AR drone 2.0. It is shown that the strategy can be used to: (1) trigger a final approach response during a constant divergence landing with fixed gain, (2) estimate the distance in hover, and (3) estimate distances during an entire landing if the robot uses adaptive gain control to continuously stay on the 'edge of oscillation.'

  10. Remo Dance Motion Estimation with Markerless Motion Capture Using The Optical Flow Method

    Directory of Open Access Journals (Sweden)

    Neny Kurniati

    2016-03-01

    Full Text Available Motion capture has been developed and applied in various fields, one of them is dancing. Remo dance is a dance from East Java that tells the struggle of a prince who fought on the battlefield. Remo dancer does not use body-tight costume. He wears a few costume pieces and accessories, so required a motion detection method that can detect limb motion which does not damage the beauty of the costumes and does not interfere motion of the dancer. The method is Markerless Motion Capture. Limbs motions are partial behavior. This means that all limbs do not move simultaneously, but alternately. It required motion tracking to detect parts of the body moving and where the direction of motion. Optical flow is a method that is suitable for the above conditions. Moving body parts will be detected by the bounding box. A bounding box differential value between frames can determine the direction of the motion and how far the object is moving. The optical flow method is simple and does not require a monochrome background. This method does not use complex feature extraction process so it can be applied to real-time motion capture. Performance of motion detection with optical flow method is determined by the value of the ratio between the area of the blob and the area of the bounding box. Estimate coordinates are not necessarily like original coordinates, but if the chart of estimate motion similar to the chart of the original motion, it means motion estimation it can be said to have the same motion with the original. Keywords: Motion Capture, Markerless, Remo Dance, Optical Flow

  11. Validation of spectral domain optical coherence tomographic Doppler shifts using an in vitro flow model.

    Science.gov (United States)

    Kagemann, Larry; Wollstein, Gadi; Ishikawa, Hiroshi; Townsend, Kelly A; Schuman, Joel S

    2009-02-01

    To validate velocity measurements produced by spectral domain optical coherence tomography (SD-OCT) in an in vitro laminar flow model. A 30-mL syringe filled with skim milk was inserted into a syringe pump. Intravenous (i.v.) tubing connected the syringe within the pump to a glass capillary tube (internal diameter, 0.579 mm) shallowly embedded in agarose gel, then to a collection reservoir. SD-OCT imaging was performed with an anterior segment eye scanner and optics engine coupled with a 100-nm bandwidth broadband superluminescent diode. Scan density of 128 x 128 A-scans was spread over a 4 x 4 mm area, and each A-scan was 2 mm in length. Fifteen sequential stationary A-scans were obtained at each 128 x 128 position, and Doppler shifts were calculated from temporal changes in phase. The beam-to-flow vector Doppler angle was determined from three-dimensional scans. In all reflectance and Doppler images, a clear laminar flow pattern was observed, with v(max) appearing in the center of the flow column. Phase wrapping was observed at all measured flow velocities, and fringe washout progressively shattered reflectance and phase signals beyond the Nyquist limit. The observed percentages of the velocity profile at or below Nyquist frequency was highly correlated with the predicted percentages (R(2)=0.934; P=0.007). SD-OCT provides objective Doppler measurements of laminar fluid flow in an in vitro flow system in a range up to the Nyquist limit.

  12. AN AERIAL-IMAGE DENSE MATCHING APPROACH BASED ON OPTICAL FLOW FIELD

    Directory of Open Access Journals (Sweden)

    W. Yuan

    2016-06-01

    Full Text Available Dense matching plays an important role in many fields, such as DEM (digital evaluation model producing, robot navigation and 3D environment reconstruction. Traditional approaches may meet the demand of accuracy. But the calculation time and out puts density is hardly be accepted. Focus on the matching efficiency and complex terrain surface matching feasibility an aerial image dense matching method based on optical flow field is proposed in this paper. First, some high accurate and uniformed control points are extracted by using the feature based matching method. Then the optical flow is calculated by using these control points, so as to determine the similar region between two images. Second, the optical flow field is interpolated by using the multi-level B-spline interpolation in the similar region and accomplished the pixel by pixel coarse matching. Final, the results related to the coarse matching refinement based on the combined constraint, which recognizes the same points between images. The experimental results have shown that our method can achieve per-pixel dense matching points, the matching accuracy achieves sub-pixel level, and fully meet the three-dimensional reconstruction and automatic generation of DSM-intensive matching’s requirements. The comparison experiments demonstrated that our approach’s matching efficiency is higher than semi-global matching (SGM and Patch-based multi-view stereo matching (PMVS which verifies the feasibility and effectiveness of the algorithm.

  13. Translational Optic Flow Induces Shifts in Direction of Active Forward and Backward Self-Motion

    Directory of Open Access Journals (Sweden)

    Kenzo Sakurai

    2011-05-01

    Full Text Available Previously, we reported that when observers passively experience real linear oscillatory somatic motion while viewing orthogonal visual optic flow patterns, their perceived motion direction is intermediate to those specified by visual and vestibular information individually (Sakurai et al., 2002, ACV; 2003, ECVP; 2010, VSS; Kubodera et al., 2010, APCV. Here, we extend those studies to active somatic motion, measuring the angular shift in body direction after active body motion while viewing synchronized orthogonal optic flow. Experimental visual stimuli consisted of 1 second of translating leftward (rightward random-dots and 1 second of random noise. Control stimuli consisted of two 1-second intervals of random noise separated by a static interval. Observers viewed the stimulus for 30 seconds through a face-mounted display while actively stepping forward and backward such that their forward body movement was synchronized with the random-dot translational motion. Observers' body direction was measured before and after each trial. Translational optic flow induced shifts in body direction that were opposite to shifts in perceived direction with passive viewing in our previous reports. Observers may have compensated their body motion in response to perceived direction shifts similar to those we reported for passive viewing.

  14. Noninvasive optical measurement of cerebral blood flow in mice using molecular dynamics analysis of indocyanine green.

    Directory of Open Access Journals (Sweden)

    Taeyun Ku

    Full Text Available In preclinical studies of ischemic brain disorders, it is crucial to measure cerebral blood flow (CBF; however, this requires radiological techniques with heavy instrumentation or invasive procedures. Here, we propose a noninvasive and easy-to-use optical imaging technique for measuring CBF in experimental small animals. Mice were injected with indocyanine green (ICG via tail-vein catheterization. Time-series near-infrared fluorescence signals excited by 760 nm light-emitting diodes were imaged overhead by a charge-coupled device coupled with an 830 nm bandpass-filter. We calculated four CBF parameters including arrival time, rising time and mean transit time of a bolus and blood flow index based on time and intensity information of ICG fluorescence dynamics. CBF maps were generated using the parameters to estimate the status of CBF, and they dominantly represented intracerebral blood flows in mice even in the presence of an intact skull and scalp. We demonstrated that this noninvasive optical imaging technique successfully detected reduced local CBF during middle cerebral artery occlusion. We further showed that the proposed method is sufficiently sensitive to detect the differences between CBF status in mice anesthetized with either isoflurane or ketamine-xylazine, and monitor the dynamic changes in CBF after reperfusion during transient middle cerebral artery occlusion. The near-infrared optical imaging of ICG fluorescence combined with a time-series analysis of the molecular dynamics can be a useful noninvasive tool for preclinical studies of brain ischemia.

  15. Accurate optical flow field estimation using mechanical properties of soft tissues

    Science.gov (United States)

    Mehrabian, Hatef; Karimi, Hirad; Samani, Abbas

    2009-02-01

    A novel optical flow based technique is presented in this paper to measure the nodal displacements of soft tissue undergoing large deformations. In hyperelasticity imaging, soft tissues maybe compressed extensively [1] and the deformation may exceed the number of pixels ordinary optical flow approaches can detect. Furthermore in most biomedical applications there is a large amount of image information that represent the geometry of the tissue and the number of tissue types present in the organ of interest. Such information is often ignored in applications such as image registration. In this work we incorporate the information pertaining to soft tissue mechanical behavior (Neo-Hookean hyperelastic model is used here) in addition to the tissue geometry before compression into a hierarchical Horn-Schunck optical flow method to overcome this large deformation detection weakness. Applying the proposed method to a phantom using several compression levels proved that it yields reasonably accurate displacement fields. Estimated displacement results of this phantom study obtained for displacement fields of 85 pixels/frame and 127 pixels/frame are reported and discussed in this paper.

  16. Modeling Human Control of Self-Motion Direction With Optic Flow and Vestibular Motion.

    Science.gov (United States)

    Zaal, Peter M T; Nieuwenhuizen, Frank M; van Paassen, Marinus M; Mulder, Max

    2013-04-01

    In this paper, we investigate the effects of visual and motion stimuli on the manual control of one's direction of self-motion. In a flight simulator, subjects conducted an active target-following disturbance-rejection task, using a compensatory display. Simulating a vehicular control task, the direction of vehicular motion was shown on the outside visual display in two ways: an explicit presentation using a symbol and an implicit presentation, namely, through the focus of radial outflow that emerges from optic flow. In addition, the effects of the relative strength of congruent vestibular motion cues were investigated. The dynamic properties of human visual and vestibular motion perception paths were modeled using a control-theoretical approach. As expected, improved tracking performance was found for the configurations that explicitly showed the direction of self-motion. The human visual time delay increased with approximately 150 ms for the optic flow conditions, relative to explicit presentations. Vestibular motion, providing higher order information on the direction of self-motion, allowed subjects to partially compensate for this visual perception delay, improving performance. Parameter estimates of the operator control model show that, with vestibular motion, the visual feedback becomes stronger, indicating that operators are more confident to act on optic flow information when congruent vestibular motion cues are present.

  17. A Stochastic Approach for Blurred Image Restoration and Optical Flow Computation on Field Image Sequence

    Institute of Scientific and Technical Information of China (English)

    高文; 陈熙霖

    1997-01-01

    The blur in target images caused by camera vibration due to robot motion or hand shaking and by object(s) moving in the background scene is different to deal with in the computer vision system.In this paper,the authors study the relation model between motion and blur in the case of object motion existing in video image sequence,and work on a practical computation algorithm for both motion analysis and blut image restoration.Combining the general optical flow and stochastic process,the paper presents and approach by which the motion velocity can be calculated from blurred images.On the other hand,the blurred image can also be restored using the obtained motion information.For solving a problem with small motion limitation on the general optical flow computation,a multiresolution optical flow algoritm based on MAP estimation is proposed. For restoring the blurred image ,an iteration algorithm and the obtained motion velocity are used.The experiment shows that the proposed approach for both motion velocity computation and blurred image restoration works well.

  18. An Aerial-Image Dense Matching Approach Based on Optical Flow Field

    Science.gov (United States)

    Yuan, Wei; Chen, Shiyu; Zhang, Yong; Gong, Jianya; Shibasaki, Ryosuke

    2016-06-01

    Dense matching plays an important role in many fields, such as DEM (digital evaluation model) producing, robot navigation and 3D environment reconstruction. Traditional approaches may meet the demand of accuracy. But the calculation time and out puts density is hardly be accepted. Focus on the matching efficiency and complex terrain surface matching feasibility an aerial image dense matching method based on optical flow field is proposed in this paper. First, some high accurate and uniformed control points are extracted by using the feature based matching method. Then the optical flow is calculated by using these control points, so as to determine the similar region between two images. Second, the optical flow field is interpolated by using the multi-level B-spline interpolation in the similar region and accomplished the pixel by pixel coarse matching. Final, the results related to the coarse matching refinement based on the combined constraint, which recognizes the same points between images. The experimental results have shown that our method can achieve per-pixel dense matching points, the matching accuracy achieves sub-pixel level, and fully meet the three-dimensional reconstruction and automatic generation of DSM-intensive matching's requirements. The comparison experiments demonstrated that our approach's matching efficiency is higher than semi-global matching (SGM) and Patch-based multi-view stereo matching (PMVS) which verifies the feasibility and effectiveness of the algorithm.

  19. Influence of Optic-Flow Information Beyond the Velocity Field on the Active Control of Heading

    Directory of Open Access Journals (Sweden)

    Li Li

    2011-05-01

    Full Text Available We examined both the sufficiency of the optic-flow velocity field and the influence of optic-flow information beyond the velocity field on the active control of heading. The display simulated a vehicle traveling on a circular path through a random-dot 3D cloud under a static or a dynamic scene in which dots were periodically redrawn to remove information beyond a velocity field. Participants used a joystick, under either velocity and acceleration control dynamics, to steer and align the vehicle orientation with their perceived heading while experiencing random perturbations to the vehicle orientation. Frequency response (Bode plots show reasonably good performance under both display conditions with a decrease in gain and an increase in phase lag for the dynamic scene for both control dynamics. The performance data were then fit by a Crossover Model to identify reaction time and lead time constant to determine how much participants anticipated future heading to generate lead control. Reaction time was longer and lead time constant was smaller for the dynamic than the static scene for both control dynamics. We conclude that the velocity field alone is sufficient to support closed-loop heading control, but optic-flow information beyond the velocity field improves visuomotor performance in self-motion control.

  20. Toward Optic Flow Regulation for Wall-Following and Centring Behaviours

    Directory of Open Access Journals (Sweden)

    Julien Serres

    2006-06-01

    Full Text Available In our ongoing project on the autonomous guidance of Micro-Air Vehicles (MAVs in confined indoor and outdoor environments, we have developed a bio-inspired optic flow based autopilot enabling a hovercraft to travel safely, and avoid the walls of a corridor. The hovercraft is an air vehicle endowed with natural roll and pitch stabilization characteristics, in which planar flight control can be developed conveniently. It travels at a constant ground height (∼2mm and senses the environment by means of two lateral eyes that measure the right and left optic flows (OFs. The visuomotor feedback loop, which is called LORA(1 (Lateral Optic flow Regulation Autopilot, Mark 1, consists of a lateral OF regulator that adjusts the hovercraft's yaw velocity and keeps the lateral OF constant on one wall equal to an OF set-point. Simulations have shown that the hovercraft manages to navigate in a corridor at a “preset” groundspeed (1m/s without requiring a supervisor to make it switch abruptly between the control-laws corresponding to behaviours such as automatic wall-following, automatic centring, and automatically reacting to an opening encountered on a wall. The passive visual sensors and the simple control system used here are suitable for use on MAVs with an avionic payload of only a few grams.

  1. Toward optic flow regulation for wall-following and centring behaviours

    Directory of Open Access Journals (Sweden)

    Franck Ruffier

    2008-11-01

    Full Text Available In our ongoing project on the autonomous guidance of Micro-Air Vehicles (MAVs in confined indoor and outdoor environments, we have developed a bio-inspired optic flow based autopilot enabling a hovercraft to travel safely, and avoid the walls of a corridor. The hovercraft is an air vehicle endowed with natural roll and pitch stabilization characteristics, in which planar flight control can be developed conveniently. It travels at a constant ground height (~2mm and senses the environment by means of two lateral eyes that measure the right and left optic flows (OFs. The visuomotor feedback loop, which is called LORA(1 (Lateral Optic flow Regulation Autopilot, Mark 1, consists of a lateral OF regulator that adjusts the hovercraft's yaw velocity and keeps the lateral OF constant on one wall equal to an OF set-point. Simulations have shown that the hovercraft manages to navigate in a corridor at a "pre-set" groundspeed (1m/s without requiring a supervisor to make it switch abruptly between the control-laws corresponding to behaviours such as automatic wall-following, automatic centring, and automatically reacting to an opening encountered on a wall. The passive visual sensors and the simple control system used here are suitable for use on MAVs with an avionic payload of only a few grams.

  2. Multiplexed fibre optic sensors for monitoring resin infusion, flow, and cure in composite material processing

    Science.gov (United States)

    Chehura, Edmon; Jarzebinska, Renata; Da Costa, Elisabete F. R.; Skordos, Alexandros A.; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.

    2013-04-01

    The infusion, flow and cure of RTM6 resin in a carbon fibre reinforced composite preform have been monitored using a variety of multiplexed fibre optic sensors. Optical fibre Fresnel sensors and tilted fibre Bragg grating (TFBG) sensors were configured to monitor resin infusion/flow in-plane of the component. The results obtained from the different sensors were in good agreement with visual observations. The degree of cure was monitored by Fresnel sensors via a measurement of the refractive index of the resin which was converted to degree of cure using a calibration determined from Differential Scanning Calorimetry. Fibre Bragg grating sensors fabricated in highly linearly birefringent fibre were used to monitor the development of transverse strain during the cure process, revealing through-thickness material shrinkage of about 712 μɛ and residual strain of 223 μɛ. An alternative approach to infusion monitoring, based on an array of multiplexed tapered optical fibre sensors interrogated using optical frequency domain reflectometry, was also investigated in a separate carbon fibre preform that was infused with RTM6 resin.

  3. A rapid and reversible skull optical clearing method for monitoring cortical blood flow

    Science.gov (United States)

    Zhang, Chao; Zhao, Yanjie; Shi, Rui; Zhu, Dan

    2016-03-01

    In vivo cortex optical imaging is of great important for revealing both structural and functional architecture of brain with high temporal-spatial resolution. To reduce the limitation of turbid skull, researchers had to establish various skull windows or directly expose cortex through craniotomy. Here we developed a skull optical clearing method to make skull transparent. Laser speckle contrast imaging technique was used to monitor the cortical blood flow after topical treatment with the optical clearing agents. The results indicated that the image contrast increased gradually, and then maintained at a high level after 15 min for adult mice, which made the image quality and resolution of micro-vessels nearly approximate to those of exposed cortex. Both the cortical blood flow velocity almost kept constant after skull became transparent. Besides, the treatment of physiological saline on the skull could make skull return to the initial state again and the skull could become transparent again when SOCS retreated it. Thus, we could conclude that the skull optical clearing method was rapid, valid, reversible and safe, which provided us available approach for performing the cortical structural and functional imaging at high temporal-spatial resolution.

  4. Assessment of skin flaps using optically based methods for measuring blood flow and oxygenation.

    Science.gov (United States)

    Payette, Jeri R; Kohlenberg, Elicia; Leonardi, Lorenzo; Pabbies, Arone; Kerr, Paul; Liu, Kan-Zhi; Sowa, Michael G

    2005-02-01

    The objective of this study was to compare two noninvasive techniques, laser Doppler and optical spectroscopy, for monitoring hemodynamic changes in skin flaps. Animal models for assessing these changes in microvascular free flaps and pedicle flaps were investigated. A 2 x 3-cm free flap model based on the epigastric vein-artery pair and a reversed MacFarlane 3 x 10-cm pedicle flap model were used in this study. Animals were divided into four groups, with groups 1 (n = 6) and 2 (n = 4) undergoing epigastric free flap surgery and groups 3 (n = 3) and 4 (n = 10) undergoing pedicle flap surgery. Groups 1 and 4 served as controls for each of the flap models. Groups 2 and 3 served as ischemia-reperfusion models. Optical spectroscopy provides a measure of hemoglobin oxygen saturation and blood volume, and the laser Doppler method measures blood flow. Optical spectroscopy proved to be consistently more reliable in detecting problems with arterial in flow compared with laser Doppler assessments. When spectroscopy was used in an imaging configuration, oxygen saturation images of the entire flap were generated, thus creating a visual picture of global flap health. In both single-point and imaging modes the technique was sensitive to vessel manipulation, with the immediate post operative images providing an accurate prediction of eventual outcome. This series of skin flap studies suggests a potential role for optical spectroscopy and spectroscopic imaging in the clinical assessment of skin flaps.

  5. [Peculiarities of ocular blood flow in ischemic optic neuropathy and normal tension glaucoma].

    Science.gov (United States)

    Mamikonian, V R; Galoian, N S; Sheremet, N L; Kazarian, E E; Kharlap, S I; Shmeleva-Demir, O A; Andzhelova, D V; Tatevosian, A A

    2013-01-01

    Characteristics of ocular hemodynamics in ischemic optic neuropathy (ION) outcome and normal tension glaucoma (NTG), the conditions that are difficult to be differentially diagnosed, have been investigated. The study enrolled 32 patients (40 eyes) with ION outcome, 26 patients (46 eyes) with NTG, and 20 patients (32 eyes) with no ocular pathology. Besides the standard ophthalmological examination, color Doppler imaging of ocular vessels, evaluation of ocular blood flow volume and individual normal range of intraocular pressure (flowmetry) were performed in all cases. The results showed that an excess of the actual intraocular pressure (IOP) over the individual normal range was much higher in patients with NTG than in patients with ION (39% and 14.5% correspondingly). It was also found that NTG is associated with a more significant decrease of ocular blood flow volume (30.1% in average) in comparison to ION outcome (11%). In both conditions a decrease in velocity parameters of the blood flow in main ocular vessels was registered, however, ocular hemodynamics changes appeared to be more severe in patients with glaucomatous optic neuropathy. A statistically reliable correlation between volumetric and velocity parameters of ocular blood flow has been discovered.

  6. Blood flow changes after unilateral carotid artery ligation monitored by optical coherence tomography

    Science.gov (United States)

    Ma, Yushu; Liang, Chengbo; Suo, Yanyan; Zhao, Yuqian; Wang, Yi; Xu, Tao; Wang, Ruikang; Ma, Zhenhe

    2016-03-01

    Unilateral carotid artery ligation which could induce adaptive improvement is a classic model that has been widely used to study pathology of ischemic disease. In those studies, blood flow is an important parameter to characterize the ischemia. Optical coherence tomography (OCT) is a powerful imaging modality which can provide depth resolved images in biological tissue with high spatial and temporal resolution. SPF rats was anesthetized with isoflurane and divided into two groups. In first group, bilateral carotid artery was surgically exposed, and then left carotid artery was ligated. Blood flow changes of the contralateral carotid artery was monitored using high speed spectral domain optical coherence tomography, including the absolute flow velocity and the flow volume. In the other group, skull window was opened at the ipsilateral cerebral cortex of ligation and blood supply of small artery was measured before and after the ligation. The measured results demonstrate the blood supply compensation process after unilateral carotid artery ligation. With the superiority of high resolution, OCT is an effective technology in monitoring results of carotid artery after ligation.

  7. New insight into rheology and flow properties of complex fluids with Doppler optical coherence tomography

    Science.gov (United States)

    Haavisto, Sanna; Koponen, Antti I.; Salmela, Juha

    2014-01-01

    Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT) is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field. PMID:24904920

  8. New Insight into Rheology and Flow Properties of Complex Fluids with Doppler Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Juha eSalmela

    2014-05-01

    Full Text Available Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field.

  9. Single-step stereolithography of complex anatomical models for optical flow measurements.

    Science.gov (United States)

    de Zélicourt, Diane; Pekkan, Kerem; Kitajima, Hiroumi; Frakes, David; Yoganathan, Ajit P

    2005-02-01

    Transparent stereolithographic rapid prototyping (RP) technology has already demonstrated in literature to be a practical model construction tool for optical flow measurements such as digital particle image velocimetry (DPIV), laser doppler velocimetry (LDV), and flow visualization. Here, we employ recently available transparent RP resins and eliminate time-consuming casting and chemical curing steps from the traditional approach. This note details our methodology with relevant material properties and highlights its advantages. Stereolithographic model printing with our procedure is now a direct single-step process, enabling faster geometric replication of complex computational fluid dynamics (CFD) models for exact experimental validation studies. This methodology is specifically applied to the in vitro flow modeling of patient-specific total cavopulmonary connection (TCPC) morphologies. The effect of RP machining grooves, surface quality, and hydrodynamic performance measurements as compared with the smooth glass models are also quantified.

  10. Reciprocal inhibitory connections within a neural network for rotational optic-flow processing

    Directory of Open Access Journals (Sweden)

    Juergen Haag

    2007-10-01

    Full Text Available Neurons in the visual system of the blowfly have large receptive fields that are selective for specific optic flow fields. Here, we studied the neural mechanisms underlying flow-field selectivity in proximal Vertical System (VS-cells, a particular subset of tangential cells in the fly. These cells have local preferred directions that are distributed such as to match the flow field occurring during a rotation of the fly. However, the neural circuitry leading to this selectivity is not fully understood. Through dual intracellular recordings from proximal VS cells and other tangential cells, we characterized the specific wiring between VS cells themselves and between proximal VS cells and horizontal sensitive tangential cells. We discovered a spiking neuron (Vi involved in this circuitry that has not been described before. This neuron turned out to be connected to proximal VS cells via gap junctions and, in addition, it was found to be inhibitory onto VS1.

  11. New Insight into Rheology and Flow Properties of Complex Fluids with Doppler Optical Coherence Tomography

    Science.gov (United States)

    Salmela, Juha; Haavisto, Sanna; Koponen, Antti

    2014-05-01

    Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT) is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field.

  12. Ultrafast all-optical switching using signal flow graph for PANDA resonator.

    Science.gov (United States)

    Bahadoran, Mahdi; Ali, Jalil; Yupapin, Preecha P

    2013-04-20

    In this paper, the bifurcation behavior of light in the PANDA ring resonator is investigated using the signal flow graph (SFG) method, where the optical transfer function for the through and drop ports of the PANDA Vernier system are derived. The optical nonlinear phenomena, such as bistability, Ikeda instability, and dynamics of light in the silicon-on-insulator (SOI) PANDA ring resonator with four couplers are studied. The transmission curves for bistability and instability as a function of the resonant mode numbers and coupling coefficients for the coupler are derived by the SFG method and simulated. The proposed system has an advantage as no optical pumping component is required. Simulated results show that closed-loop bistable switching can be generated and achieved by varying mode resonant numbers in the SOI-PANDA Vernier resonator, where a smooth and closed-loop bistable switching with low relative output/input power can be obtained and realized. The minimum through-port switching time of 1.1 ps for resonant mode numbers of 5;4;4 and minimum drop port switching time of 1.96 ps for resonant mode numbers of 9;7;7 of the PANDA Vernier resonator are achieved, which makes the PANDA Vernier resonator an operative component for optical applications, such as optical signal processing and a fast switching key in photonics integrated circuits.

  13. Microfluidic Flows and Heat Transfer and Their Influence on Optical Modes in Microstructure Fibers

    Directory of Open Access Journals (Sweden)

    Edward Davies

    2014-11-01

    Full Text Available A finite element analysis (FEA model has been constructed to predict the thermo-fluidic and optical properties of a microstructure optical fiber (MOF accounting for changes in external temperature, input water velocity and optical fiber geometry. Modeling a water laminar flow within a water channel has shown that the steady-state temperature is dependent on the water channel radius while independent of the input velocity. There is a critical channel radius below which the steady-state temperature of the water channel is constant, while above, the temperature decreases. However, the distance required to reach steady state within the water channel is dependent on both the input velocity and the channel radius. The MOF has been found capable of supporting multiple modes. Despite the large thermo-optic coefficient of water, the bound modes’ response to temperature was dominated by the thermo-optic coefficient of glass. This is attributed to the majority of the light being confined within the glass, which increased with increasing external temperature due to a larger difference in the refractive index between the glass core and the water channel.

  14. OPTICAL FLOW APPLIED TO TIME-LAPSE IMAGE SERIES TO ESTIMATE GLACIER MOTION IN THE SOUTHERN PATAGONIA ICE FIELD

    OpenAIRE

    E. Lannutti; Lenzano, M. G.; Toth, C; L. Lenzano; Rivera, A.

    2016-01-01

    In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically complex and hard to access areas, deploying time-lapse imaging sensors, optical flow may provide an efficient solution at good spatial and te...

  15. Perceiving collision impacts in Alzheimer’s disease: The effect of retinal eccentricity on optic flow deficits

    Directory of Open Access Journals (Sweden)

    Nam-Gyoon eKim

    2015-11-01

    Full Text Available The present study explored whether the optic flow deficit in Alzheimer’s disease (AD reported in the literature transfers to different types of optic flow, in particular, one that specifies collision impacts with upcoming surfaces, with a special focus on the effect of retinal eccentricity. Displays simulated observer movement over a ground plane toward obstacles lying in the observer’s path. Optical expansion was modulated by varying tau-dot. The visual field was masked either centrally (peripheral vision or peripherally (central vision using masks ranging from 10° to 30° in diameter in steps of 10°. Participants were asked to indicate whether their approach would result in collision or no collision with the obstacles. Results showed that AD patients’ sensitivity to tau-dot was severely compromised, not only for central vision but also for peripheral vision, compared to age- and education-matched elderly controls. The results demonstrated that AD patients’ optic flow deficit is not limited to radial optic flow but includes also the optical pattern engendered by tau-dot. Further deterioration in the capacity to extract tau-dot to determine potential collisions in conjunction with the inability to extract heading information from radial optic flow would exacerbate AD patients’ difficulties in navigation and visuospatial orientation.

  16. APPLICATION OF CHEMOMETRICS FOR ANALYSIS OF BIOAEROSOLS BY FLOW-OPTICAL METHOD

    Directory of Open Access Journals (Sweden)

    E. S. Khudyakov

    2016-01-01

    Full Text Available Subject of Research. The informativity of detection channels for bioaerosol analyzer is investigated. Analyzer operation is based on flow-optical method. Method. Measurements of fluorescence and the light scattering of separate bioaerosol particles were performed in five and two spectral ranges, correspondingly. The signals of soil dust particles were registered and used as an imitation of background atmospheric particles. For fluorescenceinduction of bioaerosol particles we used light sources: a laser one with a wavelength equal to 266 nm and 365 nm LED source.Main Results. Using chemometric data processing the classification of informative parameters has been performed and three most significant parameters have been chosen which account for 72% of total data variance. Testing has been done using SIMCA and k-NN methods. It has been proved that the use of the original and the reduced sets of three parameters produces comparable accuracy for classification of bioaerosols. Practical Relevance. The possibility of rapid detection and identification of bioaerosol particles of 1-10 microns respirable fraction (hindering in the human respiratory system by flow-optical method on a background of non-biological particles is demonstrated. The most informative optical spectral ranges for development of compact and inexpensive analyzer are chosen.

  17. Optical studies of the flow start-up processes in four convergent-divergent nozzles

    Science.gov (United States)

    Opalka, Klaus O.

    1991-03-01

    In the context of design studies for the U.S. Large Blast/Thermal Simulator, BRL has sponsored optical studies of the flow start-up in convergent-divergent nozzles which have the flow-initiating diaphragm located in the nozzle throat. The experiments were performed in the 200 mm shock tube at the Ernst-Mach Institute in Freiburg (Breisgau), West-Germany. The scope of the studies included divergent nozzles with half cone angles of 6, 16, 45 and 90 deg tested at seven diaphragm pressure ratios ranging from 4 to 188 and resulting in shock strengths ranging from 1.4 to 4.4. Results were summarized in graphs of significant parameters, e.g., shock formation time, flow start-up period, flow expansion angle, and shock strength versus the driver pressure ratio and further compared with numerical results obtained with the BRL-Q1D hydrocode. The numerical-experimental comparison shows qualitative agreement. The flow phenomena are generally reproduced by the computations as long as they are not strongly dependent on viscous effects. The study shows that a pressure loss of 10 percent is connected to the presence of a large area discontinuity at the exit plane of the nozzle throat when no divergent nozzle is attached. Results suggest that a 45 deg divergent nozzle may present an acceptable compromise for minimizing these pressure losses by reducing the associated area discontinuities.

  18. Spectrum of Optically Thin Advection Dominated Accretion Flow around a Black Hole Application to Sgr A*

    CERN Document Server

    Manmoto, T; Kusunose, M

    1997-01-01

    The global structure of optically thin advection dominated accretion flows which are composed of two-temperature plasma around black holes is calculated. We adopt the full set of basic equations including the advective energy transport in the energy equation for the electrons. The spectra emitted by the optically thin accretion flows are also investigated. The radiation mechanisms which are taken into accout are bremsstrahlung, synchrotron emission, and Comptonization. The calculation of the spectra and that of the structure of the accretion flows are made to be completely consistent by calculating the radiative cooling rate at each radius. As a result of the advection domination for the ions, the heat transport from the ions to the electrons becomes practically zero and the radiative cooling balances with the advective heating in the energy equation of the electrons. Following up on the successful work of Narayan et al. (1995), we applied our model to the spectrum of Sgr A*. We find that the spectrum of Sgr ...

  19. Vision Module for Mini-robots Providing Optical Flow Processing for Obstacle Avoidance

    Science.gov (United States)

    Chinapirom, Teerapat; Witkowski, Ulf; Rueckert, Ulrich

    This paper presents a flexible prototyping platform that can be efficiently used for vision systems of small mobile robots. The vision module has been integrated into the mini-robot “Khepera”. The module is utilized to realize optical flow algorithm for obstacle avoidance. The obstacles are detected from abrupt change of the normal flow vectors during operation. This technique is also inspired by visual perception of insects, which alert when an object suddenly appears nearby them. The optical flow algorithm implemented for this approach is Sum of Absolute Differences (SAD) algorithm. The SAD is programmed using the hardware description language (VHDL) efficiently utilizing the FPGA device that is the central processing device of the module. The 30x16 pixels used in SAD for block matching are computed in parallel by 16 pairs of pixels in each operation, which allows in real-time operation. Therefore, the mini-robot being equipped with our 2D vision module for the real-time image processing is able to drive autonomously without collision with obstacles, called ego-motion. The result also shows that the implementation can reduce the execution time compared to serial implementation and helps to reduce energy consumption.

  20. Real-time Detection of Moving Objects from Moving Vehicles Using Dense Stereo and Optical Flow

    Science.gov (United States)

    Talukder, Ashit; Matthies, Larry

    2004-01-01

    Dynamic scene perception is very important for autonomous vehicles operating around other moving vehicles and humans. Most work on real-time object tracking from moving platforms has used sparse features or assumed flat scene structures. We have recently extended a real-time. dense stereo system to include realtime. dense optical flow, enabling more comprehensive dynamic scene analysis. We describe algorithms to robustly estimate 6-DOF robot egomotion in the presence of moving objects using dense flow and dense stereo. We then use dense stereo and egomotion estimates to identify other moving objects while the robot itself is moving. We present results showing accurate egomotion estimation and detection of moving people and vehicles under general 6DOF motion of the robot and independently moving objects. The system runs at 18.3 Hz on a 1.4 GHz Pentium M laptop. computing 160x120 disparity maps and optical flow fields, egomotion, and moving object segmentation. We believe this is a significant step toward general unconstrained dynamic scene analysis for mobile robots, as well as for improved position estimation where GPS is unavailable.

  1. Vascular flow density in pathological myopia: an optical coherence tomography angiography study.

    Science.gov (United States)

    Mo, Jing; Duan, Anli; Chan, Szyyann; Wang, Xuefei; Wei, Wenbin

    2017-02-03

    To investigate vascular flow density in pathological myopia with optical coherence tomography (OCT) angiography. A prospective comparative study was conducted from December 2015 to March 2016. Participants were recruited in Beijing Tongren Hospital. A total of 131 eyes were enrolled, which were divided into three groups: 45 eyes with emmetropia (EM; mean spherical equivalent (MSE) 0.50D to -0.50D), 41 eyes with high myopia (HM; MSE ≤-6.00D, without pathological changes), and 45 eyes with pathological myopia (PM; MSE ≤-6.00D and axial length (AL) ≥26.5 mm, and with pathological changes). Macular, choriocapillaris and radial peripapillary capillary (RPC) flow densities were measured and compared between groups, and their relationships with AL and best corrected visual acuity (BCVA) were analysed. Significant differences were found in macular, choriocapillaris and RPC flow densities among the three groups (pdensities of the PM group were significantly decreased (pdensity was found between the PM and HM groups (p=0.731). Compared with the EM group, retinal flow density in the macular and arcuate fibre region was not decreased in the HM group. In addition, there was a negative correlation between AL and superficial macular flow density (β=-0.542, pdensity (β=-0.282, p=0.002) and RPC flow density (β=-0.522, pdensity (β=0.194, p=0.021), deep macular flow density (β=0.373, pdensity (β=0.291, p=0.001). Macular and RPC flow densities decreased in pathological myopia compared with high myopia and emmetropia. No significant decrease of retinal flow density in the macular and arcuate fibre region was found in high myopic eyes compared with emmetropic eyes. Moreover, macular and RPC flow densities were negatively related to AL, and macular flow density was positively related to BCVA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  2. Dual-beam optical coherence tomography system for quantification of flow velocity in capillary phantoms

    Science.gov (United States)

    Daly, S. M.; Silien, C.; Leahy, M. J.

    2012-03-01

    The quantification of (blood) flow velocity within the vasculature has potent diagnostic and prognostic potential. Assessment of flow irregularities in the form of increased permeability (micro haemorrhaging), the presence of avascular areas, or conversely the presence of vessels with enlarged or increased tortuosity in the acral regions of the body may provide a means of non-invasive in vivo assessment. If assessment of dermal flow dynamics were performed in a routine manner, the existence and prevalence of ailments such as diabetes mellitus, psoriatic arthritis and Raynaud's condition may be confirmed prior to clinical suspicion. This may prove advantageous in cases wherein the efficacy of a prescribed treatment is dictated by a prompt diagnosis and to alleviate patient discomfort through early detection. Optical Coherence Tomography (OCT) is an imaging modality which utilises the principle of optical interferometry to distinguish between spatial changes in refractive index within the vasculature and thus formulate a multi-dimensional representation of the structure of the epi- and dermal skin layers. The use of the Doppler functionality has been the predominant force for the quantification of moving particles within media, elucidated via estimation of the phase shift in OCT A-scans. However, the theoretical formulation for the assessment of these phase shifts dictates that the angle between the incident light source and the vessel under question be known a priori; this may be achieved via excisional biopsy of the tissue segment in question, but is counter to the non-invasive premise of the OCT technique. To address the issue of angular dependence, an alternate means of estimating absolute flow velocity is presented. The design and development of a dual-beam (db) system incorporating an optical switch mechanism for signal discrimination of two spatially disparate points enabling quasi-simultaneous multiple specimen scanning is described. A crosscorrelation (c

  3. [Flow density measurements using optical coherence tomography angiography : Impact of age and gender].

    Science.gov (United States)

    Alnawaiseh, M; Brand, C; Lauermann, J L; Eter, N

    2017-07-19

    This article presents the normative data for flow density measured using optical coherence tomography (OCT) angiography and the impact of age and gender is evaluated. In this study 58 eyes from 58 healthy volunteers with no history of any ocular disease or ocular surgery were included. The OCT angiography imaging was performed using the RTVue XR Avanti with the AngioVue (Optovue, Fremont, CA). The macula was imaged using a 3 × 3 mm scan, and the flow density data in the superficial retinal OCT angiogram and deep retinal OCT angiogram were extracted and analyzed. The groups were compared using the Mann-Whitney U‑test and the degree of correlation between two variables was expressed as the Spearman's correlation coefficient (rSp.) RESULTS: The mean subject age was 38.3 ± 14.6 years. The flow density (whole en face) in the deep retinal OCT angiogram was significantly higher compared to the flow density in the superficial retinal OCT angiogram (p density in superficial and deep OCT angiograms of the macula between males (n = 27) and females (n = 31). There was a significant correlation between the flow density in the deep retinal OCT angiogram and age (rSp. = -0.41, p = 0.001). Whereas gender has no impact on the flow density measured using OCT angiography, there was a significant correlation between the flow density in the deep retinal OCT angiogram and age.

  4. Design of a Sensor Based on Plastic Optical Fibre (POF) to Measure Fluid Flow and Turbidity.

    Science.gov (United States)

    Aiestaran, Pedro; Arrue, Jon; Zubia, Joseba

    2009-01-01

    Although many optical fibre applications are based on their capacity to transmit optical signals with low losses, it can also be desirable for the optical fibre to be strongly affected by a certain physical parameter in the environment. In this way, it can be used as a sensor for this parameter. There are many strong arguments for the use of POFs as sensors. In addition to being easy to handle and low cost, they demonstrate advantages common to all multimode optical fibres. These specifically include flexibility, small size, good electromagnetic compatibility behaviour, and in general, the possibility of measuring any phenomenon without physically interacting with it. In this paper, a sensor based on POF is designed and analysed with the aim of measuring the volume and turbidity of a low viscosity fluid, in this case water, as it passes through a pipe. A comparative study with a commercial sensor is provided to validate the proven flow measurement. Likewise, turbidity is measured using different colour dyes. Finally, this paper will present the most significant results and conclusions from all the tests which are carried out.

  5. Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods.

    Science.gov (United States)

    Fantini, Sergio; Sassaroli, Angelo; Tgavalekos, Kristen T; Kornbluth, Joshua

    2016-07-01

    Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion and supply the brain with the necessary oxygen and energy substrates. Adequate brain perfusion is required to support normal brain function, to achieve successful aging, and to navigate acute and chronic medical conditions. We review the general principles of CBF measurements and the current techniques to measure CBF based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance imaging, ultrasound techniques, thermal diffusion, and optical methods. We also review techniques for arterial blood pressure measurements as well as theoretical and experimental methods for the assessment of CA, including recent approaches based on optical techniques. The assessment of cerebral perfusion in the clinical practice is also presented. The comprehensive description of principles, methods, and clinical requirements of CBF and CA measurements highlights the potentially important role that noninvasive optical methods can play in the assessment of neurovascular health. In fact, optical techniques have the ability to provide a noninvasive, quantitative, and continuous monitor of CBF and autoregulation.

  6. Design of a Sensor Based on Plastic Optical Fibre (POF to Measure Fluid Flow and Turbidity

    Directory of Open Access Journals (Sweden)

    Joseba Zubia

    2009-05-01

    Full Text Available Although many optical fibre applications are based on their capacity to transmit optical signals with low losses, it can also be desirable for the optical fibre to be strongly affected by a certain physical parameter in the environment. In this way, it can be used as a sensor for this parameter. There are many strong arguments for the use of POFs as sensors. In addition to being easy to handle and low cost, they demonstrate advantages common to all multimode optical fibres. These specifically include flexibility, small size, good electromagnetic compatibility behaviour, and in general, the possibility of measuring any phenomenon without physically interacting with it. In this paper, a sensor based on POF is designed and analysed with the aim of measuring the volume and turbidity of a low viscosity fluid, in this case water, as it passes through a pipe. A comparative study with a commercial sensor is provided to validate the proven flow measurement. Likewise, turbidity is measured using different colour dyes. Finally, this paper will present the most significant results and conclusions from all the tests which are carried out.

  7. Optic flow odometry operates independently of stride integration in carried ants.

    Science.gov (United States)

    Pfeffer, Sarah E; Wittlinger, Matthias

    2016-09-09

    Cataglyphis desert ants are impressive navigators. When the foragers roam the desert, they employ path integration. For these ants, distance estimation is one key challenge. Distance information was thought to be provided by optic flow (OF)-that is, image motion experienced during travel-but this idea was abandoned when stride integration was discovered as an odometer mechanism in ants. We show that ants transported by nest mates are capable of measuring travel distance exclusively by the use of OF cues. Furthermore, we demonstrate that the information gained from the optic flowmeter cannot be transferred to the stride integrator. Our results suggest a dual information channel that allows the ants to measure distances by strides and OF cues, although both systems operate independently and in a redundant manner. Copyright © 2016, American Association for the Advancement of Science.

  8. Digital in-line holography for the characterization of flowing particles in astigmatic optical systems

    Science.gov (United States)

    Sentis, Matthias P. L.; Bruel, Laurent; Charton, Sophie; Onofri, Fabrice R. A.; Lamadie, Fabrice

    2017-01-01

    An extended Generalized Fresnel Transform (GFT) is proposed to account for the astigmatism introduced by optical elements described, in the paraxial approximation, with a ray transfer matrix analysis. Generalized impulse response and generalized Fresnel transfer function propagators as well as sampling conditions are derived to properly implement this transformation. As a test case, the near-field diffraction patterns and in-line holograms produced by droplets flowing in a tube with cylindrical interfaces have been simulated. A best fitting approach is introduced to retrieve, from the propagated holograms, the 3D position and size of the droplets. Several hologram focusing indicators based on the analysis of droplets focus region are also proposed to further improve the estimation of the droplets position along the optical axis. Numerical simulations and experimental results confirm the applicability and accuracy of the proposed methods.

  9. Tracking lung tumour motion using a dynamically weighted optical flow algorithm and electronic portal imaging device

    Science.gov (United States)

    Teo, P. T.; Crow, R.; Van Nest, S.; Sasaki, D.; Pistorius, S.

    2013-07-01

    This paper investigates the feasibility and accuracy of using a computer vision algorithm and electronic portal images to track the motion of a tumour-like target from a breathing phantom. A multi-resolution optical flow algorithm that incorporates weighting based on the differences between frames was used to obtain a set of vectors corresponding to the motion between two frames. A global value representing the average motion was obtained by computing the average weighted mean from the set of vectors. The tracking accuracy of the optical flow algorithm as a function of the breathing rate and target visibility was investigated. Synthetic images with different contrast-to-noise ratios (CNR) were created, and motions were tracked. The accuracy of the proposed algorithm was compared against potentiometer measurements giving average position errors of 0.6 ± 0.2 mm, 0.2 ± 0.2 mm and 0.1 ± 0.1 mm with average velocity errors of 0.2 ± 0.2 mm s-1, 0.4 ± 0.3 mm s-1 and 0.6 ± 0.5 mm s-1 for 6, 12 and 16 breaths min-1 motions, respectively. The cumulative average position error reduces more rapidly with the greater number of breathing cycles present in higher breathing rates. As the CNR increases from 4.27 to 5.6, the average relative error approaches zero and the errors are less dependent on the velocity. When tracking a tumour on a patient's digitally reconstructed radiograph images, a high correlation was obtained between the dynamically weighted optical flow algorithm, a manual delineation process and a centroid tracking algorithm. While the accuracy of our approach is similar to that of other methods, the benefits are that it does not require manual delineation of the target and can therefore provide accurate real-time motion estimation during treatment.

  10. Distributed multi-hypothesis coding of depth maps using texture motion information and optical flow

    DEFF Research Database (Denmark)

    Salmistraro, Matteo; Zamarin, Marco; Rakêt, Lars Lau

    2013-01-01

    Distributed Video Coding (DVC) is a video coding paradigm allowing a shift of complexity from the encoder to the decoder. Depth maps are images enabling the calculation of the distance of an object from the camera, which can be used in multiview coding in order to generate virtual views, but also...... information, a block-based and an optical flow-based methods are employed. Finally we fuse the proposed Side Informations using a multi-hypothesis DVC decoder, which allows us to exploit the strengths of all the proposed methods at the same time....

  11. Micro Flow Cytometry Miniaturisation - Towards in-situ Optical Phytoplankton Analysis

    Science.gov (United States)

    Zmijan, R.; Abi Kaed Bey, S.; Mowlem, M. C.; Morgan, H.

    2012-04-01

    The use of flow cytometry for studies of temporal and spatial variability of phytoplankton populations is a valuable tool contributing to research relating carbon biogeochemistry and climate change. Early designs and marine deployments of such devices started over two decades ago [1-3]. Miniaturisation and cost reduction without sacrificing performance remains a major challenge but would enable mass production and deployment. Large numbers of measurement nodes (e.g. as part of a global ocean observation system) would be possible which would increase data available over both spatial and temporal scales. This research presents two different design approaches for miniaturisation and integration of optics into a microfluidic cytometer chip. The proposed solutions are suitable for micro cytometers with external components coupled with optical fibres and were simulated and optimised using ray tracing software (Zemax). The two designs address light delivery for excitation of particles within the measurement region of the cytometer. One uses an integrated micro lens (fabricated in the chip) and the other a ball shaped micro lens manufactured separately and then inserted into the chip. Both approaches collimate the excitation light beam (from an off chip diode laser coupled with an optical fibre) into the fluidic channel. The predicted (by ray tracing) excitation beam widths are 70 and 80 µm for the integrated and the ball lens respectively, and are in agreement with experimental data presented. The proposed cytometer chip design is compatible with low cost materials (acrylic glass, cyclo-olefines) and manufacturing methods (micro milling, hot embossing, injection moulding). 1. Dubelaar, G.B.J. and P.L. Gerritzen, CytoBuoy: a step forward towards using flow cytometry in operational oceanography. Scientia Marina, 2000. 64(2): p. 255-265. 2. Peeters, J.C.H., et al., Optical Plankton Analyzer - a Flow Cytometer for Plankton Analysis .1. Design Considerations. Cytometry, 1989

  12. Multi-hypothesis Transform Domain Wyner-Ziv Video Coding including Optical Flow

    DEFF Research Database (Denmark)

    Huang, Xin; Rakêt, Lars Lau; Luong, Huynh Van

    2011-01-01

    Transform Domain Wyner-Ziv (TDWZ) video coding is an efficient Distributed Video coding solution providing new features such as low complexity encoding, by mainly exploiting the source statistics at the decoder based on the availability of decoder side information. The accuracy of the decoder side...... information has a major impact on the performance of TDWZ. In this paper, a novel multi-hypothesis based TDWZ video coding is presented to exploit the redundancy between multiple side information and the source information. The decoder used optical flow for side information calculation. Compared with the best...

  13. Analysis of heat and mass transfers in two-phase flow by coupling optical diagnostic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lemaitre, P.; Porcheron, E. [Institut de Radioprotection et de Surete Nucleaire, Saclay (France)

    2008-08-15

    During the course of a hypothetical accident in a nuclear power plant, spraying might be actuated to reduce static pressure in the containment. To acquire a better understanding of the heat and mass transfers between a spray and the surrounding confined gas, non-intrusive optical measurements have to be carried out simultaneously on both phases. The coupling of global rainbow refractometry with out-of-focus imaging and spontaneous Raman scattering spectroscopy allows us to calculate the local Spalding parameter B{sub M}, which is useful in describing heat transfer associated with two-phase flow. (orig.)

  14. Detecting moving objects in an optic flow field using direction- and speed-tuned operators.

    Science.gov (United States)

    Royden, Constance S; Holloway, Michael A

    2014-05-01

    An observer moving through a scene must be able to identify moving objects. Psychophysical results have shown that people can identify moving objects based on the speed or direction of their movement relative to the optic flow field generated by the observer's motion. Here we show that a model that uses speed- and direction-tuned units, whose responses are based on the response properties of cells in the primate visual cortex, can successfully identify the borders of moving objects in a scene through which an observer is moving.

  15. Application of bilateral filtration with weight coefficients for similarity metric calculation in optical flow computation algorithm

    Science.gov (United States)

    Panin, S. V.; Titkov, V. V.; Lyubutin, P. S.; Chemezov, V. O.; Eremin, A. V.

    2016-11-01

    Application of weight coefficients of the bilateral filter used to determine weighted similarity metrics of image ranges in optical flow computation algorithm that employs 3-dimension recursive search (3DRS) was investigated. By testing the algorithm applying images taken from the public test database Middlebury benchmark, the effectiveness of this weighted similarity metrics for solving the image processing problem was demonstrated. The necessity of matching the equation parameter values when calculating the weight coefficients aimed at taking into account image texture features was proved for reaching the higher noise resistance under the vector field construction. The adaptation technique which allows excluding manual determination of parameter values was proposed and its efficiency was demonstrated.

  16. Research on target tracking in coal mine based on optical flow method

    Science.gov (United States)

    Xue, Hongye; Xiao, Qingwei

    2015-03-01

    To recognize, track and count the bolting machine in coal mine video images, a real-time target tracking method based on the Lucas-Kanade sparse optical flow is proposed in this paper. In the method, we judge whether the moving target deviate from its trajectory, predicate and correct the position of the moving target. The method solves the problem of failure to track the target or lose the target because of the weak light, uneven illumination and blocking. Using the VC++ platform and Opencv lib we complete the recognition and tracking. The validity of the method is verified by the result of the experiment.

  17. Multi-hypothesis Transform Domain Wyner-Ziv Video Coding including Optical Flow

    DEFF Research Database (Denmark)

    Huang, Xin; Rakêt, Lars Lau; Luong, Huynh Van;

    2011-01-01

    information has a major impact on the performance of TDWZ. In this paper, a novel multi-hypothesis based TDWZ video coding is presented to exploit the redundancy between multiple side information and the source information. The decoder used optical flow for side information calculation. Compared with the best...... available single estimation mode TDWZ, the proposed multi-hypothesis based TDWZ achieves robustly better Rate-Distortion (RD) performance and the overall improvement is up to 0.6 dB at high bitrate and up to 2 dB compared with the DISCOVER TDWZ video codec....

  18. Recent Development in Optical Chemical Sensors Coupling with Flow Injection Analysis

    Directory of Open Access Journals (Sweden)

    Fuensanta Sánchez Rojas

    2006-10-01

    Full Text Available Optical techniques for chemical analysis are well established and sensors based on thesetechniques are now attracting considerable attention because of their importance in applications suchas environmental monitoring, biomedical sensing, and industrial process control. On the other hand,flow injection analysis (FIA is advisable for the rapid analysis of microliter volume samples and canbe interfaced directly to the chemical process. The FIA has become a widespread automatic analyticalmethod for more reasons; mainly due to the simplicity and low cost of the setups, their versatility, andease of assembling. In this paper, an overview of flow injection determinations by using opticalchemical sensors is provided, and instrumentation, sensor design, and applications are discussed. Thiswork summarizes the most relevant manuscripts from 1980 to date referred to analysis using opticalchemical sensors in FIA.

  19. Congestion analysis of pilgrims in Hajj and Umrah congregation using block matching and optical flow

    Science.gov (United States)

    Farooq, Sumaiyya; Khan, Shoab A.; Usman Akram, M.

    2017-01-01

    A novel method has been proposed to classify the motion of pilgrims with respect to congestion level in the holy mosque of Makkah. Millions of Muslims visit this mosque during Hajj and Umrah every year. A large number of security personnel is required to maintain the smooth flow of pilgrims in order to avert any catastrophe. Therefore, it is inevitable to design a computer aided system to reduce human effort. The proposed system pre-processes input images to segregate the moving shadows and pilgrims in order to nullify the false motion due to moving shadows. A hybrid method consisting of block matching and optical flow techniques has been used for the computation of motion vectors. Decision tree classifier is used on the number of motion vectors having non-zero magnitude. Experiments show that the proposed system has promising results yielding an accuracy of 90.58% for the congestion classification of pilgrims.

  20. Sensory prediction on a whiskered robot: A tactile analogy to "optic flow"

    Directory of Open Access Journals (Sweden)

    Christopher L Schroeder

    2012-10-01

    Full Text Available When an animal moves an array of sensors (e.g., the hand, the eye through the environment, spatial and temporal gradients of sensory data are related by the velocity of the moving sensory array. In vision, the relationship between spatial and temporal brightness gradients is quantified in the optical flow equation. In the present work, we suggest an analog to optical flow for the rodent vibrissal (whisker array, in which the perceptual intensity that flows over the array is bending moment. Changes in bending moment are directly related to radial object distance, defined as the distance between the base of a whisker and the point of contact with the object. Using both simulations and a 1x5 array (row of artificial whiskers, we demonstrate that local object curvature can be estimated based on differences in radial distance across the array. We then develop two algorithms, both based on tactile flow, to predict the future contact points that will be obtained as the whisker array translates along the object. The translation of the robotic whisker array represents the rat's head velocity. The first algorithm uses a calculation of the local object slope, while the second uses a calculation of the local object curvature. Both algorithms successfully predict future contact points for simple surfaces. The algorithm based on curvature was found to more accurately predict future contact points as surfaces became more irregular. We quantify the inter-related effects of whisker spacing and the object’s spatial frequencies, and examine the issues that arise in the presence of real-world noise, friction, and slip.

  1. Sensory prediction on a whiskered robot: a tactile analogy to "optical flow".

    Science.gov (United States)

    Schroeder, Christopher L; Hartmann, Mitra J Z

    2012-01-01

    When an animal moves an array of sensors (e.g., the hand, the eye) through the environment, spatial and temporal gradients of sensory data are related by the velocity of the moving sensory array. In vision, the relationship between spatial and temporal brightness gradients is quantified in the "optical flow" equation. In the present work, we suggest an analog to optical flow for the rodent vibrissal (whisker) array, in which the perceptual intensity that "flows" over the array is bending moment. Changes in bending moment are directly related to radial object distance, defined as the distance between the base of a whisker and the point of contact with the object. Using both simulations and a 1×5 array (row) of artificial whiskers, we demonstrate that local object curvature can be estimated based on differences in radial distance across the array. We then develop two algorithms, both based on tactile flow, to predict the future contact points that will be obtained as the whisker array translates along the object. The translation of the robotic whisker array represents the rat's head velocity. The first algorithm uses a calculation of the local object slope, while the second uses a calculation of the local object curvature. Both algorithms successfully predict future contact points for simple surfaces. The algorithm based on curvature was found to more accurately predict future contact points as surfaces became more irregular. We quantify the inter-related effects of whisker spacing and the object's spatial frequencies, and examine the issues that arise in the presence of real-world noise, friction, and slip.

  2. Detection of three-dimensional surfaces from optic flow: the effects of noise.

    Science.gov (United States)

    Andersen, G J; Wuestefeld, A P

    1993-09-01

    Previous research (Andersen, 1989) has suggested that the recovery of 3-D shape from nonsmooth optic flow (motion transparency) can be performed by segregating surfaces according to the distributions of velocities present in the flow field. Five experiments were conducted to examine this hypothesis in a surface detection paradigm and to determine the limitations of human observers to detect 3-D surfaces in the presence of noise. Two display types were examined: a flow field that simulated a surface corrugated in depth and a flow field that simulated a random volume. In addition, two types of noise were examined: a distribution of noise velocities that overlapped or did not overlap the velocity distribution that defined the surface. Corrugation frequency and surface density were also examined. Detection performance increased with decreasing corrugation frequency, decreasing noise density, and decreasing surface density. Overall, the subjects demonstrated remarkable tolerance to the presence of noise and, for some conditions, could discriminate surface from random conditions when noise density was twice the surface density. Discrimination accuracy was greater for the nonoverlapping than for the overlapping noise, providing support for an analysis based on the distribution of velocities.

  3. Optical tweezers for measuring the interaction of the two single red blood cells in flow condition

    Science.gov (United States)

    Lee, Kisung; Muravyov, Alexei; Semenov, Alexei; Wagner, Christian; Priezzhev, Alexander

    2017-03-01

    Aggregation of red blood cells (RBCs) is an intrinsic property of blood, which has direct effect on the blood viscosity and therefore affects overall the blood circulation throughout the body. It is attracting interest for the research in both fundamental science and clinical application. Despite of the intensive research, the aggregation mechanism is remaining not fully clear. Recent advances in methods allowed measuring the interaction between single RBCs in a well-defined configuration leading the better understanding of the mechanism of the process. However the most of the studies were made on the static cells. Thus, the measurements in flow mimicking conditions are missing. In this work, we aim to study the interaction of two RBCs in the flow conditions. We demonstrate the characterization of the cells interaction strength (or flow tolerance) by measuring the flow velocity to be applied to separate two aggregated cells trapped by double channel optical tweezers in a desired configuration. The age-separated cells were used for this study. The obtained values for the minimum flow velocities needed to separate the two cells were found to be 78.9 +/- 6.1 μm/s and 110 +/- 13 μm/s for old and young cells respectively. The data obtained is in agreement with the observations reported by other authors. The significance of our results is in ability for obtaining a comprehensible and absolute physical value characterizing the cells interaction in flow conditions (not like the Aggregation Index measured in whole blood suspensions by other techniques, which is some abstract parameter)

  4. Efficient Foreground Extraction Based on Optical Flow and SMED for Road Traffic Analysis

    Directory of Open Access Journals (Sweden)

    K SuganyaDevi

    2015-05-01

    Full Text Available Foreground detection is a key procedure in video analysis such as object detection and tracking. Several foreground detection techniques and edge detectors have been developed until now but the problem is, usually it is difficult to obtain an optimal foreground due to weather, light, shadow and clutter interference. Background subtract is a common method in foreground detection. In background subtract noise appears at fixed place, when it is used to deal with long image sequence there may be much accumulate error in the foreground. In OF (Optical Flow noise appears randomly and this covers long distance over long period of time. Optical flow cannot get rid of the light influences which result in background noises. To overcome this SMED (Separable Morphological Edge Detector is used. SMED has robustness to light changing and even slight movement in the video sequence. This paper proposes a new foreground detection approach called OF and SMED which is more accurate in foreground detection and elimination of noises is very high. This approach is useful for efficient crowd and traffic monitoring, user friendly, highly automatic intelligent, computationally efficient system.

  5. Satellite Angular Velocity Estimation Based on Star Images and Optical Flow Techniques

    Directory of Open Access Journals (Sweden)

    Giancarmine Fasano

    2013-09-01

    Full Text Available An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components.

  6. Flow injection analysis with bioluminescence-based fiber-optic biosensors

    Science.gov (United States)

    Blum, Loic J.; Gautier, Sabine; Coulet, Pierre R.

    1991-09-01

    Fiber optic biosensors based on the firefly and the bacterial bioluminescence reactions have been constructed and incorporated in a specially designed flow-cell for the sensitive determination of ATP and NADH, respectively. The bioluminescence enzymes were immobilized on preactivated polyamide membranes which were placed in close contact with the surface on one end of a glass-fiber bundle, the other end being connected to the photomultiplier tube of a luminometer. When using the continuous-flow device with the firefly luciferase or the bacterial system immobilized separately on different membranes, the detection limit for ATP and NADH were 0.25 and 2 pmol, respectively. The versatility of the fiber optic probe has been improved by co-immobilizing the bacterial bioluminescent system and the firefly luciferase on the same support enabling the use of a single sensor for the selective, specific, and alternate determination of these two analytes. Compatible reaction conditions preserving the activity of each co-immobilized enzyme without impairing its stability were found. The selection of the appropriate reaction medium was done using a four port valve. Alternate quantification of ATP and NADH could then be performed in the linear ranges 0.25 pmol - 3 nmol and 5 pmol - 1 nmol, respectively with a RSD of 4.0 - 4.5%.

  7. Visual processing of optic flow and motor control in the human posterior cingulate sulcus.

    Science.gov (United States)

    Field, David T; Inman, Laura A; Li, Li

    2015-10-01

    Previous studies have shown that the human posterior cingulate contains a visual processing area selective for optic flow (CSv). However, other studies performed in both humans and monkeys have identified a somatotopic motor region at the same location (CMA). Taken together, these findings suggested the possibility that the posterior cingulate contains a single visuomotor integration region. To test this idea we used fMRI to identify both visual and motor areas of the posterior cingulate in the same brains and to test the activity of those regions during a visuomotor task. Results indicated that rather than a single visuomotor region the posterior cingulate contains adjacent but separate motor and visual regions. CSv lies in the fundus of the cingulate sulcus, while CMA lies in the dorsal bank of the sulcus, slightly superior in terms of stereotaxic coordinates. A surprising and novel finding was that activity in CSv was suppressed during the visuomotor task, despite the visual stimulus being identical to that used to localize the region. This may provide an important clue to the specific role played by this region in the utilization of optic flow to control self-motion.

  8. Automatic Speech Segmentation Based On Audio and Optical Flow Visual Classification

    Directory of Open Access Journals (Sweden)

    Behnam Torabi

    2014-10-01

    Full Text Available Automatic speech segmentation as an important part of speech recognition system (ASR is highly noise dependent. Noise is made by changes in the communication channel, background, level of speaking etc. In recent years, many researchers have proposed noise cancelation techniques and have added visual features from speaker’s face to reduce the effect of noise on ASR systems. Removing noise from audio signals depends on the type of the noise; so it cannot be used as a general solution. Adding visual features improve this lack of efficiency, but advanced methods of this type need manual extraction of visual features. In this paper we propose a completely automatic system which uses optical flow vectors from speaker’s image sequence to obtain visual features. Then, Hidden Markov Models are trained to segment audio signals from image sequences and audio features based on extracted optical flow. The developed segmentation system based on such method acts totally automatic and become more robust to noise.

  9. Combination of principal component analysis and optical-flow motion compensation for improved cardiac MR thermometry

    Science.gov (United States)

    Toupin, S.; de Senneville, B. Denis; Ozenne, V.; Bour, P.; Lepetit-Coiffe, M.; Boissenin, M.; Jais, P.; Quesson, B.

    2017-02-01

    The use of magnetic resonance (MR) thermometry for the monitoring of thermal ablation is rapidly expanding. However, this technique remains challenging for the monitoring of the treatment of cardiac arrhythmia by radiofrequency ablation due to the heart displacement with respiration and contraction. Recent studies have addressed this problem by compensating in-plane motion in real-time with optical-flow based tracking technique. However, these algorithms are sensitive to local variation of signal intensity on magnitude images associated with tissue heating. In this study, an optical-flow algorithm was combined with a principal component analysis method to reduce the impact of such effects. The proposed method was integrated to a fully automatic cardiac MR thermometry pipeline, compatible with a future clinical workflow. It was evaluated on nine healthy volunteers under free breathing conditions, on a phantom and in vivo on the left ventricle of a sheep. The results showed that local intensity changes in magnitude images had lower impact on motion estimation with the proposed method. Using this strategy, the temperature mapping accuracy was significantly improved.

  10. Improving the visualization of electron-microscopy data through optical flow interpolation

    KAUST Repository

    Carata, Lucian

    2013-01-01

    Technical developments in neurobiology have reached a point where the acquisition of high resolution images representing individual neurons and synapses becomes possible. For this, the brain tissue samples are sliced using a diamond knife and imaged with electron-microscopy (EM). However, the technique achieves a low resolution in the cutting direction, due to limitations of the mechanical process, making a direct visualization of a dataset difficult. We aim to increase the depth resolution of the volume by adding new image slices interpolated from the existing ones, without requiring modifications to the EM image-capturing method. As classical interpolation methods do not provide satisfactory results on this type of data, the current paper proposes a re-framing of the problem in terms of motion volumes, considering the depth axis as a temporal axis. An optical flow method is adapted to estimate the motion vectors of pixels in the EM images, and this information is used to compute and insert multiple new images at certain depths in the volume. We evaluate the visualization results in comparison with interpolation methods currently used on EM data, transforming the highly anisotropic original dataset into a dataset with a larger depth resolution. The interpolation based on optical flow better reveals neurite structures with realistic undistorted shapes, and helps to easier map neuronal connections. © 2011 ACM.

  11. An Autonomous UAV with an Optical Flow Sensor for Positioning and Navigation

    Directory of Open Access Journals (Sweden)

    Nils Gageik

    2013-10-01

    Full Text Available A procedure to control all six DOF (degrees of freedom of a UAV (unmanned aerial vehicle without an external reference system and to enable fully autonomous flight is presented here. For 2D positioning the principle of optical flow is used. Together with the output of height estimation, fusing ultrasonic, infrared and inertial and pressure sensor data, the 3D position of the UAV can be computed, controlled and steered. All data processing is done on the UAV. An external computer with a pathway planning interface is for commanding purposes only. The presented system is part of the AQopterI8 project, which aims to develop an autonomous flying quadrocopter for indoor application. The focus of this paper is 2D positioning using an optical flow sensor. As a result of the performed evaluation, it can be concluded that for position hold, the standard deviation of the position error is 10cm and after landing the position error is about 30cm.

  12. Development of Biological Movement Recognition by Interaction between Active Basis Model and Fuzzy Optical Flow Division

    Directory of Open Access Journals (Sweden)

    Bardia Yousefi

    2014-01-01

    Full Text Available Following the study on computational neuroscience through functional magnetic resonance imaging claimed that human action recognition in the brain of mammalian pursues two separated streams, that is, dorsal and ventral streams. It follows up by two pathways in the bioinspired model, which are specialized for motion and form information analysis (Giese and Poggio 2003. Active basis model is used to form information which is different from orientations and scales of Gabor wavelets to form a dictionary regarding object recognition (human. Also biologically movement optic-flow patterns utilized. As motion information guides share sketch algorithm in form pathway for adjustment plus it helps to prevent wrong recognition. A synergetic neural network is utilized to generate prototype templates, representing general characteristic form of every class. Having predefined templates, classifying performs based on multitemplate matching. As every human action has one action prototype, there are some overlapping and consistency among these templates. Using fuzzy optical flow division scoring can prevent motivation for misrecognition. We successfully apply proposed model on the human action video obtained from KTH human action database. Proposed approach follows the interaction between dorsal and ventral processing streams in the original model of the biological movement recognition. The attained results indicate promising outcome and improvement in robustness using proposed approach.

  13. Spatiotemporal Super-Resolution Reconstruction Based on Robust Optical Flow and Zernike Moment for Video Sequences

    Directory of Open Access Journals (Sweden)

    Meiyu Liang

    2013-01-01

    Full Text Available In order to improve the spatiotemporal resolution of the video sequences, a novel spatiotemporal super-resolution reconstruction model (STSR based on robust optical flow and Zernike moment is proposed in this paper, which integrates the spatial resolution reconstruction and temporal resolution reconstruction into a unified framework. The model does not rely on accurate estimation of subpixel motion and is robust to noise and rotation. Moreover, it can effectively overcome the problems of hole and block artifacts. First we propose an efficient robust optical flow motion estimation model based on motion details preserving, then we introduce the biweighted fusion strategy to implement the spatiotemporal motion compensation. Next, combining the self-adaptive region correlation judgment strategy, we construct a fast fuzzy registration scheme based on Zernike moment for better STSR with higher efficiency, and then the final video sequences with high spatiotemporal resolution can be obtained by fusion of the complementary and redundant information with nonlocal self-similarity between the adjacent video frames. Experimental results demonstrate that the proposed method outperforms the existing methods in terms of both subjective visual and objective quantitative evaluations.

  14. Music-Elicited Emotion Identification Using Optical Flow Analysis of Human Face

    Science.gov (United States)

    Kniaz, V. V.; Smirnova, Z. N.

    2015-05-01

    Human emotion identification from image sequences is highly demanded nowadays. The range of possible applications can vary from an automatic smile shutter function of consumer grade digital cameras to Biofied Building technologies, which enables communication between building space and residents. The highly perceptual nature of human emotions leads to the complexity of their classification and identification. The main question arises from the subjective quality of emotional classification of events that elicit human emotions. A variety of methods for formal classification of emotions were developed in musical psychology. This work is focused on identification of human emotions evoked by musical pieces using human face tracking and optical flow analysis. Facial feature tracking algorithm used for facial feature speed and position estimation is presented. Facial features were extracted from each image sequence using human face tracking with local binary patterns (LBP) features. Accurate relative speeds of facial features were estimated using optical flow analysis. Obtained relative positions and speeds were used as the output facial emotion vector. The algorithm was tested using original software and recorded image sequences. The proposed technique proves to give a robust identification of human emotions elicited by musical pieces. The estimated models could be used for human emotion identification from image sequences in such fields as emotion based musical background or mood dependent radio.

  15. Optimization of flow cytometric detection and cell sorting of transgenic Plasmodium parasites using interchangeable optical filters.

    Science.gov (United States)

    Vorobjev, Ivan A; Buchholz, Kathrin; Prabhat, Prashant; Ketman, Kenneth; Egan, Elizabeth S; Marti, Matthias; Duraisingh, Manoj T; Barteneva, Natasha S

    2012-09-05

    Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP)-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP) labelling is complicated by autofluorescence (AF) of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP) and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP), AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis of parasite-infected samples with in the intention of gene

  16. Optimization of flow cytometric detection and cell sorting of transgenic Plasmodium parasites using interchangeable optical filters

    Directory of Open Access Journals (Sweden)

    Vorobjev Ivan A

    2012-09-01

    Full Text Available Abstract Background Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP labelling is complicated by autofluorescence (AF of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Methods Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. Results A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP, AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Discussion Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis

  17. Massively parallel data processing for quantitative total flow imaging with optical coherence microscopy and tomography

    Science.gov (United States)

    Sylwestrzak, Marcin; Szlag, Daniel; Marchand, Paul J.; Kumar, Ashwin S.; Lasser, Theo

    2017-08-01

    We present an application of massively parallel processing of quantitative flow measurements data acquired using spectral optical coherence microscopy (SOCM). The need for massive signal processing of these particular datasets has been a major hurdle for many applications based on SOCM. In view of this difficulty, we implemented and adapted quantitative total flow estimation algorithms on graphics processing units (GPU) and achieved a 150 fold reduction in processing time when compared to a former CPU implementation. As SOCM constitutes the microscopy counterpart to spectral optical coherence tomography (SOCT), the developed processing procedure can be applied to both imaging modalities. We present the developed DLL library integrated in MATLAB (with an example) and have included the source code for adaptations and future improvements. Catalogue identifier: AFBT_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AFBT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPLv3 No. of lines in distributed program, including test data, etc.: 913552 No. of bytes in distributed program, including test data, etc.: 270876249 Distribution format: tar.gz Programming language: CUDA/C, MATLAB. Computer: Intel x64 CPU, GPU supporting CUDA technology. Operating system: 64-bit Windows 7 Professional. Has the code been vectorized or parallelized?: Yes, CPU code has been vectorized in MATLAB, CUDA code has been parallelized. RAM: Dependent on users parameters, typically between several gigabytes and several tens of gigabytes Classification: 6.5, 18. Nature of problem: Speed up of data processing in optical coherence microscopy Solution method: Utilization of GPU for massively parallel data processing Additional comments: Compiled DLL library with source code and documentation, example of utilization (MATLAB script with raw data) Running time: 1,8 s for one B-scan (150 × faster in comparison to the CPU

  18. Flow, heat transfer, and free surface shape during the optical fiber drawing process

    Science.gov (United States)

    Xiao, Zhihui

    1997-12-01

    A two-dimensional finite element model is introduced for analyzing glass and gas flows, heat transfer, and fiber formation during the optical fiber drawing process. This study consists of simulations in three different areas: the upper region, the tip region, and the whole furnace region. Conjugating the glass and gas flows and heat transfer, the shapes of an optical fiber as free surfaces in the upper neck-down and the tip regions are separately obtained by solving the coupled continuity, momentum, and energy equations. In the upper region simulation, a surface-to-surface radiation model is used for the enclosure which consists of the wall and the glass surface, and the Rosseland approximation radiation model is employed to account for the radiation effect in the glass region. In the tip region simulation, only the glass fiber region is considered and a convective heat transfer model on the fiber surface is employed to account for the energy exchange between the fiber surface and the purge gas. In the fiber, radiation in the axial direction is included. The whole furnace simulation uses a calculated fiber neck-down shape and an assumed fiber tip shape as a fixed interface and computes the convective heat transfer coefficient profile in the tip region which was used in the tip region simulation. The glass viscosity is temperature-dependent and significantly affects the fiber shape. The finite element code FIDAP is used in the study. The effects of various operating conditions such as draw speed, wall temperature distribution, and gas flow rate are studied.

  19. Axonal loss and blood flow disturbances in the natural course of indirect traumatic optic neuropathy

    Institute of Scientific and Technical Information of China (English)

    SHI Wei; WANG Huai-zhou; SONG Wei-xian; YANG Wen-li; LI Wei-ye; WANG Ning-li

    2013-01-01

    Background Indirect traumatic optic neuropathy (TON) is an acute injury of the optic nerve associated with severe visual dysfunction,which may be a result of secondary mechanical injury and vascular disorder of the optic nerve due to trauma.We analyzed the natural course of axonal loss and blood flow disturbances in patients with indirect TON to find a possible therapeutic window.Methods A cohort of 54 patients with indirect TON recruited between October 2008 and October 2010 at Beijing Tongren Hospital was retrospectively analyzed.The patients were divided into no light perception group (NLP) and better than NLP (btNLP) group.Specifically,the thickness of the retinal nerve fiber layer (RNFL) measured by spectral domain optical coherence tomography (SD-OCT),and hemodynamic parameters of the ophthalmic artery (OA),central retinal artery (CRA) and posterior ciliary artery (PCA) were determined.Results Two weeks after injury,there was a statistically significant decrease in the thickness of RNFL in the btNLP group as compared with the fellow control eyes (P <0.05).In contrast,in the NLP group,RNFL thickness slightly increased for 2 weeks following injury,then overtly reduced after 4 weeks (P <0.05).Peak systolic velocity (PSV) of CRA was significantly decreased 4 weeks after injury (P <0.05) in both the NLP group and btNLP group (P <0.05).The thickness of RNFL in the NLP group was negatively correlated with PSV of CRA after 1 week of injury (P <0.05,r=-0.962).Conclusions SD-OCT is a useful supplement in detecting the axonal loss in TON.The dynamic change of the thickness of RNFL appears to correlate with the hemodynamic disturbances in the natural course of TON.The first 2 weeks following an injury is critical and should be considered as the therapeutic window for TON patients.

  20. Characterization of single-file flow through human retinal parafoveal capillaries using an adaptive optics scanning laser ophthalmoscope.

    Science.gov (United States)

    Tam, Johnny; Tiruveedhula, Pavan; Roorda, Austin

    2011-03-02

    Adaptive Optics Scanning Laser Ophthalmoscopy was used to noninvasively acquire videos of single-file flow through live human retinal parafoveal capillaries. Videos were analyzed offline to investigate capillary flow dynamics. Certain capillaries accounted for a clear majority of leukocyte traffic (Leukocyte-Preferred-Paths, LPPs), while other capillaries primarily featured plasma gap flow (Plasma-Gap-Capillaries, PGCs). LPPs may serve as a protective mechanism to prevent inactivated leukocytes from entering exchange capillaries, and PGCs may serve as relief valves to minimize flow disruption due to the presence of a leukocyte in a neighboring LPP.

  1. Microflow1, a sheathless fiber-optic flow cytometry biomedical platform: demonstration onboard the international space station.

    Science.gov (United States)

    Dubeau-Laramée, Geneviève; Rivière, Christophe; Jean, Isabelle; Mermut, Ozzy; Cohen, Luchino Y

    2014-04-01

    A fiber-optic based flow cytometry platform was designed to build a portable and robust instrument for space applications. At the core of the Microflow1 is a unique fiber-optic flow cell fitted to a fluidic system and fiber coupled to the source and detection channels. A Microflow1 engineering unit was first tested and benchmarked against a commercial flow cytometer as a reference in a standard laboratory environment. Testing in parabolic flight campaigns was performed to establish Microflow1's performance in weightlessness, before operating the new platform on the International Space Station. Microflow1 had comparable performances to commercial systems, and operated remarkably and robustly in weightlessness (microgravity). Microflow1 supported immunophenotyping as well as microbead-based multiplexed cytokine assays in the space environment and independently of gravity levels. Results presented here provide evidence that this fiber-optic cytometer technology is inherently compatible with the space environment with negligible compromise to analytical performance.

  2. A fast inverse consistent deformable image registration method based on symmetric optical flow computation

    Science.gov (United States)

    Yang, Deshan; Li, Hua; Low, Daniel A.; Deasy, Joseph O.; El Naqa, Issam

    2008-11-01

    Deformable image registration is widely used in various radiation therapy applications including daily treatment planning adaptation to map planned tissue or dose to changing anatomy. In this work, a simple and efficient inverse consistency deformable registration method is proposed with aims of higher registration accuracy and faster convergence speed. Instead of registering image I to a second image J, the two images are symmetrically deformed toward one another in multiple passes, until both deformed images are matched and correct registration is therefore achieved. In each pass, a delta motion field is computed by minimizing a symmetric optical flow system cost function using modified optical flow algorithms. The images are then further deformed with the delta motion field in the positive and negative directions respectively, and then used for the next pass. The magnitude of the delta motion field is forced to be less than 0.4 voxel for every pass in order to guarantee smoothness and invertibility for the two overall motion fields that are accumulating the delta motion fields in both positive and negative directions, respectively. The final motion fields to register the original images I and J, in either direction, are calculated by inverting one overall motion field and combining the inversion result with the other overall motion field. The final motion fields are inversely consistent and this is ensured by the symmetric way that registration is carried out. The proposed method is demonstrated with phantom images, artificially deformed patient images and 4D-CT images. Our results suggest that the proposed method is able to improve the overall accuracy (reducing registration error by 30% or more, compared to the original and inversely inconsistent optical flow algorithms), reduce the inverse consistency error (by 95% or more) and increase the convergence rate (by 100% or more). The overall computation speed may slightly decrease, or increase in most cases

  3. A fast inverse consistent deformable image registration method based on symmetric optical flow computation

    Energy Technology Data Exchange (ETDEWEB)

    Yang Deshan; Li Hua; Low, Daniel A; Deasy, Joseph O; Naqa, Issam El [Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, LL, St. Louis, MO 63110 (United States)

    2008-11-07

    Deformable image registration is widely used in various radiation therapy applications including daily treatment planning adaptation to map planned tissue or dose to changing anatomy. In this work, a simple and efficient inverse consistency deformable registration method is proposed with aims of higher registration accuracy and faster convergence speed. Instead of registering image I to a second image J, the two images are symmetrically deformed toward one another in multiple passes, until both deformed images are matched and correct registration is therefore achieved. In each pass, a delta motion field is computed by minimizing a symmetric optical flow system cost function using modified optical flow algorithms. The images are then further deformed with the delta motion field in the positive and negative directions respectively, and then used for the next pass. The magnitude of the delta motion field is forced to be less than 0.4 voxel for every pass in order to guarantee smoothness and invertibility for the two overall motion fields that are accumulating the delta motion fields in both positive and negative directions, respectively. The final motion fields to register the original images I and J, in either direction, are calculated by inverting one overall motion field and combining the inversion result with the other overall motion field. The final motion fields are inversely consistent and this is ensured by the symmetric way that registration is carried out. The proposed method is demonstrated with phantom images, artificially deformed patient images and 4D-CT images. Our results suggest that the proposed method is able to improve the overall accuracy (reducing registration error by 30% or more, compared to the original and inversely inconsistent optical flow algorithms), reduce the inverse consistency error (by 95% or more) and increase the convergence rate (by 100% or more). The overall computation speed may slightly decrease, or increase in most cases

  4. Design & development of a galvanometer inspired dual beam optical coherence tomography system for flow velocity quantification of the microvasculature

    OpenAIRE

    McElligott-Daly, Susan; Jonathan, E.; Martin J. Leahy

    2011-01-01

    peer-reviewed This paper reports initial experimentation of a dual beam flow velocity estimation setup based on optical coherence tomography (OCT) for biomedical applications. The proposed work incorporates a low cost switching mechanism (rotating galvanometer mirror) for optical signal discrimination between adjacent fiber channels enabling quasisimultaneous multiple specimen scanning. A cascaded interferometric design is used with two sample output arms orientated in parallel to eacho...

  5. Characterization of a Low-Cost Optical Flow Sensor When Using an External Laser as a Direct Illumination Source

    Directory of Open Access Journals (Sweden)

    Jordi Palacín

    2011-12-01

    Full Text Available In this paper, a low cost optical flow sensor is combined with an external laser device to measure surface displacements and mechanical oscillations. The measurement system is based on applying coherent light to a diffuser surface and using an optical flow sensor to analyze the reflected and transferred light to estimate the displacement of the surface or the laser spot. This work is focused on the characterization of this measurement system, which can have the optical flow sensor placed at different angles and distances from the diffuser surface. The results have shown that the displacement of the diffuser surface is badly estimated when the optical mouse sensor is placed in front of the diffuser surface (angular orientation >150° while the highest sensitivity is obtained when the sensor is located behind the diffuser surface and on the axis of the laser source (angular orientation 0°. In this case, the coefficient of determination of the measured displacement, R2, was very high (>0.99 with a relative error of less than 1.29%. Increasing the distance between the surface and the sensor also increased the sensitivity which increases linearly, R2 = 0.99. Finally, this measurement setup was proposed to measure very low frequency mechanical oscillations applied to the laser device, up to 0.01 Hz in this work. The results have shown that increasing the distance between the surface and the optical flow sensor also increases the sensitivity and the measurement range.

  6. Production of Hyperpolarized 129Xe Gas Without Nitrogen by Optical Pumping at 133Cs D2 line in Flow System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xin; SUN Xian-Ping; LUO Jun; ZENG Xi-Zhi; LIU Mai-Li; ZHAN Ming-Sheng

    2004-01-01

    @@ We report production of hyperpolarized 129Xe gas via spin-exchange with optically pumped Cs atoms at the D2 line, achieved at low magnetic field in a flow system and in the absence of nitrogen gas. The nuclear spin polarization of hyperpolarized 129Xe gas is enhanced by a factor of 10000 compared to that without optical pumping under the same condition, which corresponds to polarization of about 2.66%. Due to the high spin polarization, the radiation damping of hyperpolarized 129Xe gas has also been observed in the flow system.

  7. Application of the optical flow method for the experimental analysis of turbulent flame propagation in a transparent engine

    Science.gov (United States)

    Barone, Mario; Lombardi, Simone; Continillo, Gaetano; Sementa, Paolo; Vaglieco, Bianca Maria

    2016-12-01

    This paper illustrates the analysis conducted on high-definition, high sampling rate image sequences collected in experiments with a single spark ignition optically accessible engine. Images are first processed to identify the reaction front, and then analyzed by an optical flow estimation technique. The results show that each velocity component of the estimated flow field has an ECDF very similar to the CDF of a Gaussian distribution, whereas the velocity magnitude has an ECDF well fitted by a Rayleigh probability distribution. The proposed non-intrusive method provides a fast statistical characterization of the flame propagation phenomenon in the engine combustion chamber.

  8. Imaging internal flows in a drying sessile polymer dispersion drop using Spectral Radar Optical Coherence Tomography (SR-OCT).

    Science.gov (United States)

    Manukyan, Selin; Sauer, Hans M; Roisman, Ilia V; Baldwin, Kyle A; Fairhurst, David J; Liang, Haida; Venzmer, Joachim; Tropea, Cameron

    2013-04-01

    In this work, we present the visualization of the internal flows in a drying sessile polymer dispersion drop on hydrophilic and hydrophobic surfaces with Spectral Radar Optical Coherence Tomography (SR-OCT). We have found that surface features such as the initial contact angle and pinning of the contact line, play a crucial role on the flow direction and final shape of the dried drop. Moreover, imaging through selection of vertical slices using optical coherence tomography offers a feasible alternative compared to imaging through selection of narrow horizontal slices using confocal microscopy for turbid, barely transparent fluids.

  9. Optic flow-based vision system for autonomous 3D localization and control of small aerial vehicles

    OpenAIRE

    Kendoul, Farid; Fantoni, Isabelle; Nonami, Kenzo

    2009-01-01

    International audience; The problem considered in this paper involves the design of a vision-based autopilot for small and micro Unmanned Aerial Vehicles (UAVs). The proposed autopilot is based on an optic flow-based vision system for autonomous localization and scene mapping, and a nonlinear control system for flight control and guidance. This paper focusses on the development of a real-time 3D vision algorithm for estimating optic flow, aircraft self-motion and depth map, using a low-resolu...

  10. Fiber-optic flow sensors for high-temperature environment operation up to 800°C.

    Science.gov (United States)

    Chen, Rongzhang; Yan, Aidong; Wang, Qingqing; Chen, Kevin P

    2014-07-01

    This Letter presents an all-optical high-temperature flow sensor based on hot-wire anemometry. High-attenuation fibers (HAFs) were used as the heating elements. High-temperature-stable regenerated fiber Bragg gratings were inscribed in HAFs and in standard telecom fibers as temperature sensors. Using in-fiber light as both the heating power source and the interrogation light source, regenerative fiber Bragg grating sensors were used to gauge the heat transfer from an optically powered heating element induced by the gas flow. Reliable gas flow measurements were demonstrated between 0.066  m/s and 0.66  m/s from the room temperature to 800°C. This Letter presents a compact, low-cost, and multiflexible approach to measure gas flow for high-temperature harsh environments.

  11. Modeling of skin cooling, blood flow, and optical properties in wounds created by electrical shock

    Science.gov (United States)

    Nguyen, Thu T. A.; Shupp, Jeffrey W.; Moffatt, Lauren T.; Jordan, Marion H.; Jeng, James C.; Ramella-Roman, Jessica C.

    2012-02-01

    High voltage electrical injuries may lead to irreversible tissue damage or even death. Research on tissue injury following high voltage shock is needed and may yield stage-appropriate therapy to reduce amputation rate. One of the mechanisms by which electricity damages tissue is through Joule heating, with subsequent protein denaturation. Previous studies have shown that blood flow had a significant effect on the cooling rate of heated subcutaneous tissue. To assess the thermal damage in tissue, this study focused on monitoring changes of temperature and optical properties of skin next to high voltage wounds. The burns were created between left fore limb and right hind limb extremities of adult male Sprague-Dawley rats by a 1000VDC delivery shock system. A thermal camera was utilized to record temperature variation during the exposure. The experimental results were then validated using a thermal-electric finite element model (FEM).

  12. Optical flow based deformable volume registration using a novel second-order regularization prior

    Science.gov (United States)

    Grbić, Saša; Urschler, Martin; Pock, Thomas; Bischof, Horst

    2010-03-01

    Nonlinear image registration is an initial step for a large number of medical image analysis applications. Optical flow based intensity registration is often used for dealing with intra-modality applications involving motion differences. In this work we present an energy functional which uses a novel, second-order regularization prior of the displacement field. Compared to other methods our scheme is robust to non-Gaussian noise and does not penalize locally affine deformation fields in homogeneous areas. We propose an efficient and stable numerical scheme to find the minimizer of the presented energy. We implemented our algorithm using modern consumer graphics processing units and thereby increased the execution performance dramatically. We further show experimental evaluations on clinical CT thorax data sets at different breathing states and on dynamic 4D CT cardiac data sets.

  13. Robust Face Location and Tracking Using Optical Flow and Genetic Algorithms

    Institute of Scientific and Technical Information of China (English)

    WANG Yanjiang; YUAN Baozong

    2001-01-01

    This paper presents a new and robustapproach to the detection, localization and tracking ofa human face in image sequences. First, a fast algo-rithm based on the neighbor-point-reliability is pro-posed to calculate the optical flow, which is used toextract the motion region. Then the hair and thehead knowledges are used to locate the face area. Forface tracking, a new genetic algorithms-based dynamictemplate-matching method is applied to search thenew position of the face in each new video frame. Ex-perimental results show that the proposed face track-ing method is fast and robust to illumination, faceposes, facial expressions and image distractors suchas facial occlusion by hands.

  14. Optical flow based Kalman filter for body joint prediction and tracking using HOG-LBP matching

    Science.gov (United States)

    Nair, Binu M.; Kendricks, Kimberley D.; Asari, Vijayan K.; Tuttle, Ronald F.

    2014-03-01

    We propose a real-time novel framework for tracking specific joints in the human body on low resolution imagery using optical flow based Kalman tracker without the need of a depth sensor. Body joint tracking is necessary for a variety of surveillance based applications such as recognizing gait signatures of individuals, identifying the motion patterns associated with a particular action and the corresponding interactions with objects in the scene to classify a certain activity. The proposed framework consists of two stages; the initialization stage and the tracking stage. In the initialization stage, the joints to be tracked are either manually marked or automatically obtained from other joint detection algorithms in the first few frames within a window of interest and appropriate image descriptions of each joint are computed. We employ the use of a well-known image coding scheme known as the Local Binary Patterns (LBP) to represent the joint local region where this image coding removes the variance to non-uniform lighting conditions as well as enhances the underlying edges and corner. The image descriptions of the joint region would then include a histogram computed from the LBP-coded ROI and a HOG (Histogram of Oriented Gradients) descriptor to represent the edge information. Next the tracking stage can be divided into two phases: Optical flow based detection of joints in corresponding frames of the sequence and prediction /correction phases of Kalman tracker with respect to the joint coordinates. Lucas Kanade optical flow is used to locate the individual joints in consecutive frames of the video based on their location in the previous frame. But more often, mismatches can occur due to the rotation of the joint region and the rotation variance of the optical flow matching technique. The mismatch is then determined by comparing the joint region descriptors using Chi-squared metric between a pair of frames and depending on this statistic, either the prediction

  15. Optical principle of pH measurement for detection of auxin flow through cellular membrane

    Science.gov (United States)

    Podrazky, Ondrej; Mrazek, Jan; Seidl, Miroslav; Kasik, Ivan; Tobiska, Petr; Matejec, Vlastimil; Martan, Tomas; Aubrecht, Jan

    2007-05-01

    The paper shows an approach to the determination of pH changes of solutions with a fine spatial resolution by means of fiber-optic tapers and fluorescence detection. This approach can be adopted for the determination of auxin flow through celluar membranes. Spectral absorption and fluorescence of pH transducers, namely of fluorescein, carboxyfluorescein, 6,8-dihydroxy-1,3-pyrenedisulfonic acid disodium salt and 2',7'-bis(2-carbonylethyl)-5(6)-carboxyfluorescein, were tested. The approach, based on the determination of a shift of the maxima of their fluorescence peaks, was employed for processing the measured fluorescence data in bulk solutions. Suitable tapered fiber probes were prepared and in vitro demonstrated for pH monitoring in a pH range from 6 to 7.

  16. Initial assessment of facial nerve paralysis based on motion analysis using an optical flow method.

    Science.gov (United States)

    Samsudin, Wan Syahirah W; Sundaraj, Kenneth; Ahmad, Amirozi; Salleh, Hasriah

    2016-01-01

    An initial assessment method that can classify as well as categorize the severity of paralysis into one of six levels according to the House-Brackmann (HB) system based on facial landmarks motion using an Optical Flow (OF) algorithm is proposed. The desired landmarks were obtained from the video recordings of 5 normal and 3 Bell's Palsy subjects and tracked using the Kanade-Lucas-Tomasi (KLT) method. A new scoring system based on the motion analysis using area measurement is proposed. This scoring system uses the individual scores from the facial exercises and grades the paralysis based on the HB system. The proposed method has obtained promising results and may play a pivotal role towards improved rehabilitation programs for patients.

  17. On how the optical depth tunes the effects of ISM neutral atom flow on debris disks

    CERN Document Server

    Marzari, Francesco

    2011-01-01

    The flux of ISM neutral atoms surrounding stars and their environment affects the motion of dust particles in debris disks, causing a significant dynamical evolution. Large values of eccentricity and inclination can be excited and strong correlations settle in among the orbital angles. This dynamical behaviour, in particular for bound dust grains, can potentially cause significant asymmetries in dusty disks around solar type stars which might be detected by observations. However, the amount of orbital changes due to this non--gravitational perturbation is strongly limited by the collisional lifetime of dust particles. We show that for large values of the disk's optical depth the influence of ISM flow on the disk shape is almost negligible because the grains are collisionally destroyed before they can accumulate enough orbital changes due to the ISM perturbations. On the other hand, for values smaller than $10^{-3}$, peculiar asymmetric patterns appear in the density profile of the disk when we consider 1-10 m...

  18. Motion states extraction with optical flow for rat-robot automatic navigation.

    Science.gov (United States)

    Zhang, Xinlu; Sun, Chao; Zheng, Nenggan; Chen, Weidong; Zheng, Xiaoxiang

    2012-01-01

    The real-time acquisition of precise motion states is significant and difficult for bio-robot automatic navigation. In this paper, we propose a real-time video-tracking algorithm to extract motion states of rat-robots in complex environment using optical flow. The rat-robot's motion states, including location, speed and motion trend, are acquired accurately in real time. Compared with the traditional methods based on single frame image, our algorithm using consecutive frames provides more exact and rich motion information for the automatic navigation of bio-robots. The video of the manual navigation experiments on rat-robots in eight-arm maze is applied to test this algorithm. The average computation time is 25.76 ms which is less than the speed of image acquisition. The results show that our method could extract the motion states with good performance of accuracy and time consumption.

  19. Computer-aided diagnosis of breast MRI with high accuracy optical flow estimation

    Science.gov (United States)

    Meyer-Baese, Anke; Barbu, Adrian; Lobbes, Marc; Hoffmann, Sebastian; Burgeth, Bernhard; Kleefeld, Andreas; Meyer-Bäse, Uwe

    2015-05-01

    Non-mass enhancing lesions represent a challenge for the radiological reading. They are not well-defined in both morphology (geometric shape) and kinetics (temporal enhancement) and pose a problem to lesion detection and classification. To enhance the discriminative properties of an automated radiological workflow, the correct preprocessing steps need to be taken. In an usual computer-aided diagnosis (CAD) system, motion compensation plays an important role. To this end, we employ a new high accuracy optical flow based motion compensation algorithm with robustification variants. An automated computer-aided diagnosis system evaluates the atypical behavior of these lesions, and additionally considers the impact of non-rigid motion compensation on a correct diagnosis.

  20. Optical measurements of gas bubbles in oil behind a cavitating micro-orifice flow

    Science.gov (United States)

    Iben, Uwe; Wolf, Fabian; Freudigmann, Hans-Arndt; Fröhlich, Jochen; Heller, Winfried

    2015-06-01

    In hydraulic systems, it is common for air release to occur behind valves or throttles in the form of bubbles. These air bubbles can affect the behavior and the performance of these systems to a substantial extent. In the paper, gas release in a liquid flow behind an orifice is analyzed by optical methods for various operation points. The bubbles are observed with a digital camera, and a detection algorithm based on the Hough transformation is used to determine their number and size. The appearance of gas bubbles is very sensitive to the inlet and outlet pressure of the orifice. Gas bubbles are only observed if choking cavitation occurs. An empirical relationship between an adjusted cavitation number and the appearance of gas release is presented. It is assumed that the observed bubbles contain mostly air. With the applied pressure differences, up to 30 % of the dissolved air was degassed in the form of bubbles.

  1. Fast left ventricle tracking in CMR images using localized anatomical affine optical flow

    Science.gov (United States)

    Queirós, Sandro; Vilaça, João. L.; Morais, Pedro; Fonseca, Jaime C.; D'hooge, Jan; Barbosa, Daniel

    2015-03-01

    In daily cardiology practice, assessment of left ventricular (LV) global function using non-invasive imaging remains central for the diagnosis and follow-up of patients with cardiovascular diseases. Despite the different methodologies currently accessible for LV segmentation in cardiac magnetic resonance (CMR) images, a fast and complete LV delineation is still limitedly available for routine use. In this study, a localized anatomically constrained affine optical flow method is proposed for fast and automatic LV tracking throughout the full cardiac cycle in short-axis CMR images. Starting from an automatically delineated LV in the end-diastolic frame, the endocardial and epicardial boundaries are propagated by estimating the motion between adjacent cardiac phases using optical flow. In order to reduce the computational burden, the motion is only estimated in an anatomical region of interest around the tracked boundaries and subsequently integrated into a local affine motion model. Such localized estimation enables to capture complex motion patterns, while still being spatially consistent. The method was validated on 45 CMR datasets taken from the 2009 MICCAI LV segmentation challenge. The proposed approach proved to be robust and efficient, with an average distance error of 2.1 mm and a correlation with reference ejection fraction of 0.98 (1.9 +/- 4.5%). Moreover, it showed to be fast, taking 5 seconds for the tracking of a full 4D dataset (30 ms per image). Overall, a novel fast, robust and accurate LV tracking methodology was proposed, enabling accurate assessment of relevant global function cardiac indices, such as volumes and ejection fraction

  2. Simultaneous optical/X-ray study of GS 1354-64 (=BW Cir) during hard outburst: evidence for optical cyclo-synchrotron emission from the hot accretion flow

    Science.gov (United States)

    Pahari, Mayukh; Gandhi, Poshak; Charles, Philip A.; Kotze, Marissa M.; Altamirano, Diego; Misra, Ranjeev

    2017-07-01

    We present results from simultaneous optical [South African Large Telescope (SALT)] and X-ray (Swift and INTEGRAL) observations of GS 1354-64/BW Cir during the 2015 hard state outburst. During the rising phase, optical/X-ray time series shows a strong anti-correlation with X-ray photons lagging optical. Optical and X-ray power spectra show quasi-periodic oscillations (QPOs) at a frequency of ˜18 mHz with a confidence level of at least 99 per cent. Simultaneous fitting of Swift/XRT and INTEGRAL spectra in the range 0.5-1000.0 keV shows non-thermal, power-law-dominated (>90 per cent) spectra with a hard power-law index of 1.48 ± 0.03, inner disc temperature of 0.12 ± 0.01 keV and an inner disc radius of ˜3000 km. All evidence is consistent with cyclo-synchrotron radiation in a non-thermal, hot electron cloud extending to ˜100 Schwarzschild radii being a major physical process for the origin of optical photons. At outburst peak about one month later, when the X-ray flux rises and the optical drops, the apparent features in the optical/X-ray correlation vanish and the optical auto correlation widens. Although ˜0.19 Hz QPO is observed from the X-ray power spectra, the optical variability is dominated by the broad-band noise, and the inner disc temperature increases. These results support a change in the dominant optical emission source between outburst rise and peak, consistent with a weakening of hot flow as the disc moves in.

  3. Performances of Three Miniature Bio-inspired Optic Flow Sensors under Natural Conditions

    Directory of Open Access Journals (Sweden)

    Stéphane Viollet

    2011-02-01

    Full Text Available Considerable attention has been paid during the last decade to vision-based navigation systems based on optic flow (OF cues. OF-based systems have been implemented on an increasingly large number of sighted autonomous robotic platforms. Nowadays, the OF is measured using conventional cameras, custom-made sensors and even optical mouse chips. However, very few studies have dealt so far with the reliability of these OF sensors in terms of their precision, range and sensitivity to illuminance variations. Three miniature custom-made OF sensors developed at our laboratory, which were composed of photosensors connected to an OF processing unit were tested and compared in this study, focusing on their responses and characteristics in real indoor and outdoor environments in a large range of illuminance. It was concluded that by combining a custom-made aVLSI retina equipped with Adaptive Pixels for Insect-based Sensor (APIS with a bio-inspired visual processing system, it is possible to obtain highly effective miniature sensors for measuring the OF under real environmental conditions.

  4. Afocal Optical Flow Sensor for Reducing Vertical Height Sensitivity in Indoor Robot Localization and Navigation

    Directory of Open Access Journals (Sweden)

    Dong-Hoon Yi

    2015-05-01

    Full Text Available This paper introduces a novel afocal optical flow sensor (OFS system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively.

  5. VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD

    Directory of Open Access Journals (Sweden)

    Johan Debayle

    2011-05-01

    Full Text Available An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.

  6. Afocal optical flow sensor for reducing vertical height sensitivity in indoor robot localization and navigation.

    Science.gov (United States)

    Yi, Dong-Hoon; Lee, Tae-Jae; Cho, Dong-Il Dan

    2015-05-13

    This paper introduces a novel afocal optical flow sensor (OFS) system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length) system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively.

  7. Using binary optical elements (BOEs) to generate rectangular spots for illumination in micro flow cytometer

    Science.gov (United States)

    Zhao, Jingjing; You, Zheng

    2016-01-01

    This work introduces three rectangular quasi-flat-top spots, which are provided by binary optical elements (BOEs) and utilized for the illumination in a microflow cytometer. The three spots contain, respectively, one, two, and three rectangles (R1, R2, and R3). To test the performance of this mechanism, a microflow cytometer is established by integrating the BOEs and a three-dimensional hydrodynamic focusing chip. Through the experiments of detecting fluorescence microbeads, the three spots present good fluorescence coefficients of variation in comparison with those derived from commercial instruments. Benefiting from a high spatial resolution, when using R1 spot, the micro flow cytometer can perform a throughput as high as 20 000 events per second (eps). Illuminated by R2 or R3 spot, one bead emits fluorescence twice or thrice, thus the velocity can be measured in real time. Besides, the R3 spot provides a long-time exposure, which is conducive to improving fluorescence intensity and the measurement stability. In brief, using the spots shaped and homogenized by BOEs for illumination can increase the performance and the functionality of a micro flow cytometer. PMID:27733892

  8. HEADING RECOVERY FROM OPTIC FLOW: COMPARING PERFORMANCE OF HUMANS AND COMPUTATIONAL MODELS

    Directory of Open Access Journals (Sweden)

    Andrew John Foulkes

    2013-06-01

    Full Text Available Human observers can perceive their direction of heading with a precision of about a degree. Several computational models of the processes underpinning the perception of heading have been proposed. In the present study we set out to assess which of four candidate models best captured human performance; the four models we selected reflected key differences in terms of approach and methods to modelling optic flow processing to recover movement parameters. We first generated a performance profile for human observers by measuring how performance changed as we systematically manipulated both the quantity (number of dots in the stimulus per frame and quality (amount of 2D directional noise of the flow field information. We then generated comparable performance profiles for the four candidate models. Models varied markedly in terms of both their performance and similarity to human data. To formally assess the match between the models and human performance we regressed the output of each of the four models against human performance data. We were able to rule out two models that produced very different performance profiles to human observers. The remaining two shared some similarities with human performance profiles in terms of the magnitude and pattern of thresholds. However none of the models tested could capture all aspect of the human data.

  9. Development of threedimensional optical correction method for reconstruction of flow field in droplet

    Science.gov (United States)

    Ko, Han Seo; Gim, Yeonghyeon; Kang, Seung-Hwan

    2015-11-01

    A three-dimensional optical correction method was developed to reconstruct droplet-based flow fields. For a numerical simulation, synthetic phantoms were reconstructed by a simultaneous multiplicative algebraic reconstruction technique using three projection images which were positioned at an offset angle of 45°. If the synthetic phantom in a conical object with refraction index which differs from atmosphere, the image can be distorted because a light is refracted on the surface of the conical object. Thus, the direction of the projection ray was replaced by the refracted ray which occurred on the surface of the conical object. In order to prove the method considering the distorted effect, reconstruction results of the developed method were compared with the original phantom. As a result, the reconstruction result of the method showed smaller error than that without the method. The method was applied for a Taylor cone which was caused by high voltage between a droplet and a substrate to reconstruct the three-dimensional flow fields for analysis of the characteristics of the droplet. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (No. 2013R1A2A2A01068653).

  10. Optical analysis of nanomaterial-cell interactions: flow cytometry and digital holographic microscopy

    Science.gov (United States)

    Mues, Sarah; Antunovic, Jan; Ossig, Rainer; Kemper, Björn; Schnekenburger, Jürgen

    2015-05-01

    The in vitro cytotoxicity assessment of engineered nanoparticles commonly involves the measurement of different endpoints like the formation of reactive oxygen species, cell viability or cell death. Usually these parameters are determined by optical readouts of enzymatically converted substrates that often interfere with the tested nanomaterials. Using cell viability (WST-8) and cell death (LDH) as parameter we have initially investigated the toxic effects of spherical (NM 300) and rod shaped (NM 302) silver nanomaterials with a matrix of four cell lines representing different functions: lung and kidney epithelial cells, macrophages and fibroblasts. In addition, we have used a label-free flow cytometer configuration to investigate interactions of particles and macrophages by side scatter signal analysis. Finally, we explored digital holographic microscopy (DHM) for multimodal label-free analysis of nanomaterial toxicity. Quantitative DHM phase images were analyzed for cell thickness, volume, density, dry mass and refractive index. We could demonstrate that silver spheres lead to more cytotoxic effects than rods in all four examined cell lines and both assay. Exemplarily a dose dependent interaction increase of cells with NM 300 and NM 302 analyzed by flow cytometry is shown. Furthermore, we found that the refractive index of cells is influenced by incubation with NM 300 in a decreasing manner. A 24 hours time-lapse measurement revealed a dose dependent decrease of dry mass and surface area development indicating reduced cell viability and cell death. Our results demonstrate digital holographic microscopy and flow cytometry as valuable label-free tools for nanomaterial toxicity and cell interaction studies.

  11. Depth discrimination in acousto-optic cerebral blood flow measurement simulation

    Science.gov (United States)

    Tsalach, A.; Schiffer, Z.; Ratner, E.; Breskin, I.; Zeitak, R.; Shechter, R.; Balberg, M.

    2016-03-01

    Monitoring cerebral blood flow (CBF) is crucial, as inadequate perfusion, even for relatively short periods of time, may lead to brain damage or even death. Thus, significant research efforts are directed at developing reliable monitoring tools that will enable continuous, bed side, simple and cost-effective monitoring of CBF. All existing non invasive bed side monitoring methods, which are mostly NIRS based, such as Laser Doppler or DCS, tend to underestimate CBF in adults, due to the indefinite effect of extra-cerebral tissues on the obtained signal. If those are to find place in day to day clinical practice, the contribution of extra-cerebral tissues must be eliminated and data from the depth (brain) should be extracted and discriminated. Recently, a novel technique, based on ultrasound modulation of light was developed for non-invasive, continuous CBF monitoring (termed ultrasound-tagged light (UTL or UT-NIRS)), and shown to correlate with readings of 133Xe SPECT and laser Doppler. We have assembled a comprehensive computerized simulation, modeling this acousto-optic technique in a highly scattering media. Using the combination of light and ultrasound, we show how depth information may be extracted, thus distinguishing between flow patterns taking place at different depths. Our algorithm, based on the analysis of light modulated by ultrasound, is presented and examined in a computerized simulation. Distinct depth discrimination ability is presented, suggesting that using such method one can effectively nullify the extra-cerebral tissues influence on the obtained signals, and specifically extract cerebral flow data.

  12. Dynamics, OH distributions and UV emission of a gliding arc at various flow-rates investigated by optical measurements

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Sun, Zhiwei; Li, Zhongshan

    2014-01-01

    -state OH were investigated using planar laser-induced fluorescence. The results show that the shape, height, intensity and thickness of ground-state OH distribution vary significantly with air flow rates. Finally, UV emission of the gliding arc is measured using optical emission spectroscopy......We demonstrate a plasma discharge which is generated between two diverging electrodes and extended into a gliding arc in non-equilibrium condition by an air flow at atmospheric pressure. Effects of the air flow rates on the dynamics, ground-state OH distributions and spectral characterization of UV...

  13. Real-Time Optical Monitoring of Flow Kinetics and Gas Phase Reactions Under High-Pressure OMCVD Conditions

    Science.gov (United States)

    Dietz, N.; McCall, S.; Bachmann, K. J.

    2001-01-01

    This contribution addresses the real-time optical characterization of gas flow and gas phase reactions as they play a crucial role for chemical vapor phase depositions utilizing elevated and high pressure chemical vapor deposition (HPCVD) conditions. The objectives of these experiments are to validate on the basis of results on real-time optical diagnostics process models simulation codes, and provide input parameter sets needed for analysis and control of chemical vapor deposition at elevated pressures. Access to microgravity is required to retain high pressure conditions of laminar flow, which is essential for successful acquisition and interpretation of the optical data. In this contribution, we describe the design and construction of the HPCVD system, which include access ports for various optical methods of real-time process monitoring and to analyze the initial stages of heteroepitaxy and steady-state growth in the different pressure ranges. To analyze the onset of turbulence, provisions are made for implementation of experimental methods for in-situ characterization of the nature of flow. This knowledge will be the basis for the design definition of experiments under microgravity, where gas flow conditions, gas phase and surface chemistry, might be analyzed by remote controlled real-time diagnostics tools, developed in this research project.

  14. Combined application of ultrasonic waves, magnetic fields and optical flow in the rehabilitation of patients and disabled people

    OpenAIRE

    Chukhraiev, N.; Vladimirov, A.; Vilcahuaman, L.; Zukow, W; Samosyuk, N.; Chukhraieva, E.; Butskaya, L.

    2016-01-01

    SHUPYK NATIONAL MEDICAL ACADEMY OF POSTGRADUATE EDUCATION PONTIFICAL CATHOLIC UNIVERSITY OF PERU RADOM UNIVERSITY SCM «MEDICAL INNOVATIVE TECHNOLOGIES»       Chukhraiev N., Vladimirov А., Vilcahuamаn L., Zukow W., Samosyuk N., Chukhraieva E., Butskaya L.             COMBINED APPLICATION OF ULTRASONIC WAVES, MAGNETIC FIELDS AND OPTICAL FLOW IN THE REHABILITATION OF P...

  15. Effect of varying nitrogen flow rates on the optical properties of amorphous-SiCN thin films

    Science.gov (United States)

    Rahman, Mohd Azam Abdul; Tong, Goh Boon; Mahmood, Mohamad Rusop; Siong, Chiu Wee; Yian, Haw Choon; Rahman, Saadah Abdul

    2016-11-01

    Series of amorphous silicon carbon nitride (a-SiCN) films are synthesized using RF-PECVD technique on glass and silicon substrates from precursor gas of silane, methane and nitrogen. In this work, the change in nitrogen flow rate from 0 sccm to 50 sccm is a mean used to vary the elemental composition and bonding properties which lead to change in optical properties. The films thickness varies between 327 nm to 944 nm. The changes for the stated properties are discussed against the change in the stated nitrogen flow rate. The optical properties are investigated by means of UV-VIS spectroscopy in the wavelength range of 190 nm to 2500 nm. The transmittance of the films at ultra-violet wavelength is found to increases with increase in nitrogen flow rate. The index of refraction, n obtained for SiCN films from transmittance and reflectance measurements is lower compared to SiC films. The films optical band gap increases from 1.74 eV to 2.08 eV before it decreases to 1.89 eV as nitrogen flow rate increases from 0 to 50 sccm. The optical dispersion parameters were determined according to Wemple and Didomenico method.

  16. Combined application of ultrasonic waves, magnetic fields and optical flow in the rehabilitation of patients and disabled people

    OpenAIRE

    Chukhraiev, N.; Vladimirov, A.; Vilcahuaman, L.; Zukow, W.; Samosyuk, N.; Chukhraieva, E.; Butskaya, L.

    2016-01-01

    SHUPYK NATIONAL MEDICAL ACADEMY OF POSTGRADUATE EDUCATION PONTIFICAL CATHOLIC UNIVERSITY OF PERU RADOM UNIVERSITY SCM «MEDICAL INNOVATIVE TECHNOLOGIES»       Chukhraiev N., Vladimirov А., Vilcahuamаn L., Zukow W., Samosyuk N., Chukhraieva E., Butskaya L.             COMBINED APPLICATION OF ULTRASONIC WAVES, MAGNETIC FIELDS AND OPTICAL FLOW IN THE REHABILITATION OF P...

  17. Factors influencing the structure and shape of stenotic and regurgitant jets: an in vitro investigation using Doppler color flow mapping and optical flow visualization.

    Science.gov (United States)

    Krabill, K A; Sung, H W; Tamura, T; Chung, K J; Yoganathan, A P; Sahn, D J

    1989-06-01

    To evaluate factors influencing the structure and shape of stenotic and regurgitant jets, Doppler color flow mapping and optical flow visualization studies were performed with use of a syringe model with a constant rate of ejection to simulate jets of valvular regurgitation and a pulsatile flow model of the right heart chambers to simulate jets of mild, moderate and severe valvular pulmonary stenosis. Ink-(0 to 40%) glycerol-water jets (viscosity 1 to 3.5 centiPoise) were produced by injecting the fluid at a constant rate into a 10 gallon rectangular reservoir of the same still fluid through 1.4 and 3.4 mm needles. The Doppler color flow scanners imaged the laminar jet length within 3 mm of actual jet length (2 to 6 cm) and the jet width within 2 to 3 mm of the actual jet width. Jet flows with Reynolds numbers ranging from 230 to 1,200 injected into still fluid yielded jet length/width ratios that decreased with increasing Reynolds numbers and leveled off to a length/width ratio of 5-6:1 at a Reynolds number near 600. When the fluid reservoir was swirled to better mimic the effect of flow entering the same cardiac chamber from a second source, the jets showed diminution of the jet length/width ratio and a clearly defined zone of turbulence. Studies of the pulsatile flow model were performed at cardiac outputs of 1 to 6 liters/min for the normal and each stenotic valve. Mild stenosis had an orifice area of 2.8 cm2, moderate stenosis an area of 1.0 cm2 and severe stenosis an area of 0.5 cm2. Laminar jet length represented the length of the total jet, which had a symmetric width and was measured from the valve opening to a region where the jet exhibited a spray effect. Laminar jet lengths (0.2 to 1.1 cm) were imaged by Doppler color flow mapping and optical visualization only in the moderate and severely stenotic valves and only at flows less than or equal to 3 liters/min (mean Reynolds numbers less than or equal to 3,470). Beyond this flow rate the jets exhibited a

  18. Experimental Evaluation of the Applicability of Capacitive and Optical Measurement Methods for the Determination of Liquid Hydrogen Volume Flow

    Directory of Open Access Journals (Sweden)

    Gert HOLLER

    2009-08-01

    Full Text Available This paper presents a capacitive and a vision-based method for measuring the velocity of cryogenic hydrogen flows. The capacitive sensing principle exploits the spatial frequency signature of perturbations moving through a multi-electrode structure. This setup increases the sensitivity to dielectric permittivity variations compared to a simple two-electrode structure while preserving the ability to detect small perturbations. The vision-based method relies on a high-speed camera system that monitors the liquid hydrogen flow through an optical window yielding the flow velocity by cross-correlating subsequent images of the flow. Although a comprehensive analysis of the obtainable measurement uncertainty was not performed yet, current measurement results show the applicability of both principles for the non-invasive measurement of the volume flow of cryogenic fuels inside conveyor pipes.

  19. Development of a fiber-optic laser velocimeter for the study of unsteady rotating flows in spinning rocket motors

    Science.gov (United States)

    Chen, K.; Shorthill, R. W.; Flandro, G. A.

    1986-08-01

    The development of a Laser Doppler Velocimeter (LDV) designed to measure two orthogonal velocity components in a complex rotating flow is described; this flow simulates the unsteady flows encountered in spinning rocket motor operations as well as such time-dependent phenomena as low frequency acoustic oscillations. The LDV is a three watt, two color, three beam system with a velocity measurement device that follows the flow continuously without any disturbance. The focusing optics, photo multipliers, amplifiers and test chamber are mounted on a precision Genisco C-181 rate-of-return table and spun to about 60 RPM. The silicon carbide particles used for seeding follow velocity fluctuations up to several hundred KHz. Two-dimensional unsteady velocity measurement systems for water flow rotating in the horizontal direction and tilting in the vertical direction are presented and discussed.

  20. Demonstration of a Fiber Optic Regression Probe in a High-Temperature Flow

    Science.gov (United States)

    Korman, Valentin; Polzin, Kurt

    2011-01-01

    The capability to provide localized, real-time monitoring of material regression rates in various applications has the potential to provide a new stream of data for development testing of various components and systems, as well as serving as a monitoring tool in flight applications. These applications include, but are not limited to, the regression of a combusting solid fuel surface, the ablation of the throat in a chemical rocket or the heat shield of an aeroshell, and the monitoring of erosion in long-life plasma thrusters. The rate of regression in the first application is very fast, while the second and third are increasingly slower. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor is optical, using two different, co-located fiber-optics to perform the regression measurement. The disparate optical transmission properties of the two fiber-optics makes it possible to measure the regression rate by monitoring the relative light attenuation through the fibers. As the fibers regress along with the parent material in which they are embedded, the relative light intensities through the two fibers changes, providing a measure of the regression rate. The optical nature of the system makes it relatively easy to use in a variety of harsh, high temperature environments, and it is also unaffected by the presence of electric and magnetic fields. In addition, the sensor could be used to perform optical spectroscopy on the light emitted by a process and collected by fibers, giving localized measurements of various properties. The capability to perform an in-situ measurement of material regression rates is useful in addressing a variety of physical issues in various applications. An in-situ measurement allows for real-time data regarding the erosion rates, providing a quick method for

  1. Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

    Science.gov (United States)

    Werkmeister, René M.; Vietauer, Martin; Knopf, Corinna; Fürnsinn, Clemens; Leitgeb, Rainer A.; Reitsamer, Herbert; Gröschl, Martin; Garhöfer, Gerhard; Vilser, Walthard; Schmetterer, Leopold

    2014-10-01

    A wide variety of ocular diseases are associated with abnormalities in ocular circulation. As such, there is considerable interest in techniques for quantifying retinal blood flow, among which Doppler optical coherence tomography (OCT) may be the most promising. We present an approach to measure retinal blood flow in the rat using a new optical system that combines the measurement of blood flow velocities via Doppler Fourier-domain optical coherence tomography and the measurement of vessel diameters using a fundus camera-based technique. Relying on fundus images for extraction of retinal vessel diameters instead of OCT images improves the reliability of the technique. The system was operated with an 841-nm superluminescent diode and a charge-coupled device camera that could be operated at a line rate of 20 kHz. We show that the system is capable of quantifying the response of 100% oxygen breathing on the retinal blood flow. In six rats, we observed a decrease in retinal vessel diameters of 13.2% and a decrease in retinal blood velocity of 42.6%, leading to a decrease in retinal blood flow of 56.7%. Furthermore, in four rats, the response of retinal blood flow during stimulation with diffuse flicker light was assessed. Retinal vessel diameter and blood velocity increased by 3.4% and 28.1%, respectively, leading to a relative increase in blood flow of 36.2%;. The presented technique shows much promise to quantify early changes in retinal blood flow during provocation with various stimuli in rodent models of ocular diseases in rats.

  2. Evaluation of event-based algorithms for optical flow with ground-truth from inertial measurement sensor

    Directory of Open Access Journals (Sweden)

    Bodo eRückauer

    2016-04-01

    Full Text Available In this study we compare nine optical flow algorithms that locally measure the flow normal to edges according to accuracy and computation cost. In contrast to conventional, frame-based motion flow algorithms, our open-source implementations compute optical flow based on address-events from a neuromorphic Dynamic Vision Sensor (DVS. For this benchmarking we created a dataset of two synthesized and three real samples recorded from a 240x180 pixel Dynamic and Active-pixel Vision Sensor (DAVIS. This dataset contains events from the DVS as well as conventional frames to support testing state-of-the-art frame-based methods. We introduce a new source for the ground truth: In the special case that the perceived motion stems solely from a rotation of the vision sensor around its three camera axes, the true optical flow can be estimated using gyro data from the inertial measurement unit integrated with the DAVIS camera. This provides a ground-truth to which we can compare algorithms that measure optical flow by means of motion cues. An analysis of error sources led to the use of a refractory period, more accurate numerical derivatives and a Savitzky-Golay filter to achieve significant improvements in accuracy. Our pure Java implementations of two recently published algorithms reduce computational cost by up to 29% compared to the original implementations. Two of the algorithms introduced in this paper further speed up processing by a factor of 10 compared with the original implementations, at equal or better accuracy. On a desktop PC, they run in real-time on dense natural input recorded by a DAVIS camera.

  3. Evaluation of Event-Based Algorithms for Optical Flow with Ground-Truth from Inertial Measurement Sensor.

    Science.gov (United States)

    Rueckauer, Bodo; Delbruck, Tobi

    2016-01-01

    In this study we compare nine optical flow algorithms that locally measure the flow normal to edges according to accuracy and computation cost. In contrast to conventional, frame-based motion flow algorithms, our open-source implementations compute optical flow based on address-events from a neuromorphic Dynamic Vision Sensor (DVS). For this benchmarking we created a dataset of two synthesized and three real samples recorded from a 240 × 180 pixel Dynamic and Active-pixel Vision Sensor (DAVIS). This dataset contains events from the DVS as well as conventional frames to support testing state-of-the-art frame-based methods. We introduce a new source for the ground truth: In the special case that the perceived motion stems solely from a rotation of the vision sensor around its three camera axes, the true optical flow can be estimated using gyro data from the inertial measurement unit integrated with the DAVIS camera. This provides a ground-truth to which we can compare algorithms that measure optical flow by means of motion cues. An analysis of error sources led to the use of a refractory period, more accurate numerical derivatives and a Savitzky-Golay filter to achieve significant improvements in accuracy. Our pure Java implementations of two recently published algorithms reduce computational cost by up to 29% compared to the original implementations. Two of the algorithms introduced in this paper further speed up processing by a factor of 10 compared with the original implementations, at equal or better accuracy. On a desktop PC, they run in real-time on dense natural input recorded by a DAVIS camera.

  4. Sedimentation field flow fractionation and optical absorption spectroscopy for a quantitative size characterization of silver nanoparticles.

    Science.gov (United States)

    Contado, Catia; Argazzi, Roberto; Amendola, Vincenzo

    2016-11-04

    Many advanced industrial and biomedical applications that use silver nanoparticles (AgNPs), require that particles are not only nano-sized, but also well dispersed, not aggregated and not agglomerated. This study presents two methods able to give rapidly sizes of monodispersed AgNPs suspensions in the dimensional range of 20-100nm. The first method, based on the application of Mie's theory, determines the particle sizes from the values of the surface plasmon resonance wavelength (SPRMAX), read from the optical absorption spectra, recorded between 190nm and 800nm. The computed sizes were compared with those determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) and resulted in agreement with the nominal values in a range between 13% (for 20nm NPs) and 1% (for 100nm NPs), The second method is based on the masterly combination of the Sedimentation Field Flow Fractionation (SdFFF - now sold as Centrifugal FFF-CFFF) and the Optical Absorption Spectroscopy (OAS) techniques to accomplish sizes and quantitative particle size distributions for monodispersed, non-aggregated AgNPs suspensions. The SdFFF separation abilities, well exploited to size NPs, greatly benefits from the application of Mie's theory to the UV-vis signal elaboration, producing quantitative mass-based particle size distributions, from which trusted number-sized particle size distributions can be derived. The silver mass distributions were verified and supported by detecting off-line the Ag concentration with the graphite furnace atomic absorption spectrometry (GF-AAS). Copyright © 2016 Elsevier B.V. All rights reserved.

  5. An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique

    Science.gov (United States)

    Battista, L.; Sciuto, S. A.; Scorza, A.

    2013-03-01

    In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10-4 m3/s (18.0 l/min) for the mono-directional sensor and a measurement range of ±3.00 × 10-4 m3/s (±18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the

  6. An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique.

    Science.gov (United States)

    Battista, L; Sciuto, S A; Scorza, A

    2013-03-01

    In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10(-4) m(3)∕s (18.0 l∕min) for the mono-directional sensor and a measurement range of ±3.00 × 10(-4) m(3)∕s (±18.0 l∕min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono

  7. Asymmetric-detection time-stretch optical microscopy (ATOM) for ultrafast high-contrast cellular imaging in flow

    CERN Document Server

    Wong, Terence T W; Ho, Kenneth K Y; Tang, Matthew Y H; Robles, Joseph D F; Wei, Xiaoming; Chan, Antony C S; Tang, Anson H L; Lam, Edmund Y; Wong, Kenneth K Y; Chan, Godfrey C F; Shum, Ho Cheung; Tsia, Kevin K

    2013-01-01

    Accelerating imaging speed in optical microscopy is often realized at the expense of image contrast, image resolution, and detection sensitivity- a common predicament for advancing high-speed and high-throughput cellular imaging. We here demonstrate a new imaging approach, called asymmetric-detection time-stretch optical microscopy (ATOM), which can deliver ultrafast label-free high-contrast flow imaging with well delineated cellular morphological resolution and in-line optical image amplification to overcome the compromised imaging sensitivity at high speed. We show that ATOM can separately reveal the enhanced phase-gradient and absorption contrast in microfluidic live-cell imaging at a flow speed as high as ~10 m/s, corresponding to an imaging throughput of ~100,000 cells/sec. ATOM could thus be the enabling platform to meet the pressing need for intercalating optical microscopy in cellular assay, e.g. imaging flow cytometry- permitting high-throughput access to the morphological information of the individu...

  8. Asymmetric-detection time-stretch optical microscopy (ATOM) for ultrafast high-contrast cellular imaging in flow

    Science.gov (United States)

    Wong, Terence T. W.; Lau, Andy K. S.; Ho, Kenneth K. Y.; Tang, Matthew Y. H.; Robles, Joseph D. F.; Wei, Xiaoming; Chan, Antony C. S.; Tang, Anson H. L.; Lam, Edmund Y.; Wong, Kenneth K. Y.; Chan, Godfrey C. F.; Shum, Ho Cheung; Tsia, Kevin K.

    2014-01-01

    Accelerating imaging speed in optical microscopy is often realized at the expense of image contrast, image resolution, and detection sensitivity – a common predicament for advancing high-speed and high-throughput cellular imaging. We here demonstrate a new imaging approach, called asymmetric-detection time-stretch optical microscopy (ATOM), which can deliver ultrafast label-free high-contrast flow imaging with well delineated cellular morphological resolution and in-line optical image amplification to overcome the compromised imaging sensitivity at high speed. We show that ATOM can separately reveal the enhanced phase-gradient and absorption contrast in microfluidic live-cell imaging at a flow speed as high as ~10 m/s, corresponding to an imaging throughput of ~100,000 cells/sec. ATOM could thus be the enabling platform to meet the pressing need for intercalating optical microscopy in cellular assay, e.g. imaging flow cytometry – permitting high-throughput access to the morphological information of the individual cells simultaneously with a multitude of parameters obtained in the standard assay. PMID:24413677

  9. Pico-force optical exchange (pico-FOX): utilizing optical forces applied to an orthogonal electroosmotic flow for particulate enrichment from mixed sample streams.

    Science.gov (United States)

    Staton, Sarah J R; Kim, Soo Y; Hart, Sean J; Collins, Greg E; Terray, Alex

    2013-09-17

    Results are reported from a combined optical force and electrokinetic microfluidic device that separates individual particulates from molecular components in a mixed sample stream. A pico-Newton optical force was applied to an orthogonal electroosmotic flow carrying a hydrodynamically pinched, mixed sample, resulting in the separation of the various particles from the sample stream. Different combinations of polystyrene, PMMA, and silica particles with a commercially available dye were utilized to test the different separation modes available, from purely optical force to combined optical and electrophoretic forces. The impact of various particle properties on particle separation and separation efficiency were explored, including size (2, 6, 10 μm), refractive index, and electrophoretic mobility. Particle addressability was achieved by moving particles to different outlets on the basis of particle size, refractive index, and electrophoretic differences. Separations of 6 and 10 μm polystyrene particles led to only 3% particle contamination in the original sample stream and interparticle type enrichment levels >80%. The unique addressability of three different particle materials (polystyrene, PMMA, and silica) of the same size (2 μm) led to each being separated into a unique outlet without measurable contamination of the other particle types using optical force and electrophoretic mobility. In addition to particle separation, the device was able to minimize dye diffusion, leading to >95% dye recovery. This combined platform would have applications for noninvasive sample preparation of mixed molecular/particulate systems for mating with traditional analytics as well as efficient removal of harmful, degrading components from complex mixtures.

  10. Optical Flow Applied to Time-Lapse Image Series to Estimate Glacier Motion in the Southern Patagonia Ice Field

    Science.gov (United States)

    Lannutti, E.; Lenzano, M. G.; Toth, C.; Lenzano, L.; Rivera, A.

    2016-06-01

    In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically complex and hard to access areas, deploying time-lapse imaging sensors, optical flow may provide an efficient solution at good spatial and temporal resolution to describe mass motion. Several studies in computer vision and image processing community have used this method to detect large displacements. Therefore, we carried out a test of the proposed Large Displacement Optical Flow method at the Viedma Glacier, located at South Patagonia Icefield, Argentina. We collected monoscopic terrestrial time-lapse imagery, acquired by a calibrated camera at every 24 hour from April 2014 until April 2015. A filter based on temporal correlation and RGB color discretization between the images was applied to minimize errors related to changes in lighting, shadows, clouds and snow. This selection allowed discarding images that do not follow a sequence of similarity. Our results show a flow field in the direction of the glacier movement with acceleration in the terminus. We analyzed the errors between image pairs, and the matching generally appears to be adequate, although some areas show random gross errors related to the presence of changes in lighting. The proposed technique allowed the determination of glacier motion during one year, providing accurate and reliable motion data for subsequent analysis.

  11. Optical flow and inertial navigation system fusion in the UAV navigation

    Science.gov (United States)

    Popov, A.; Miller, A.; Miller, B.; Stepanyan, K.

    2016-10-01

    In recent years navigation on the basis of computation of the camera path and the distance to obstacles with the aid of field of image motion velocities (i.e. optical flow, OF) became highly demanded particularly in the area of relatively small and even micro unmanned aerial vehicles (UAV). Video sequences captured by onboard camera gives the possibility of the OF calculation with the aid of relatively simple algorithms like Lucas-Kanade. The complete OF is the linear function of linear and angular velocities of the UAV which provides an additional means for the navigation parameters estimation. Such UAV navigation approach presumes that on-board camera gives the video sequence of the underlying surface images providing the information about the UAV evolutions. Navigation parameters are extracted on the basis of exact OF formulas which gives the observation process description for estimation based on Kalman filtering. One can expect the high accuracy of the estimated parameters (linear and angular velocities) because their number is substantially less than the number of measurements (practically the number of the camera pixels).

  12. Design of jitter compensation algorithm for robot vision based on optical flow and Kalman filter.

    Science.gov (United States)

    Wang, B R; Jin, Y L; Shao, D L; Xu, Y

    2014-01-01

    Image jitters occur in the video of the autonomous robot moving on bricks road, which will reduce robot operation precision based on vision. In order to compensate the image jitters, the affine transformation kinematics were established for obtaining the six image motion parameters. The feature point pair detecting method was designed based on Eigen-value of the feature windows gradient matrix, and the motion parameters equation was solved using the least square method and the matching point pairs got based on the optical flow. The condition number of coefficient matrix was proposed to quantificationally analyse the effect of matching errors on parameters solving errors. Kalman filter was adopted to smooth image motion parameters. Computing cases show that more point pairs are beneficial for getting more precise motion parameters. The integrated jitters compensation software was developed with feature points detecting in subwindow. And practical experiments were conducted on two mobile robots. Results show that the compensation costing time is less than frame sample time and Kalman filter is valid for robot vision jitters compensation.

  13. Optical oximetry of volume-oscillating vascular compartments: contributions from oscillatory blood flow

    Science.gov (United States)

    Kainerstorfer, Jana M.; Sassaroli, Angelo; Fantini, Sergio

    2016-10-01

    We present a quantitative analysis of dynamic diffuse optical measurements to obtain oxygen saturation of hemoglobin in volume oscillating compartments. We used a phasor representation of oscillatory hemodynamics at the heart rate and respiration frequency to separate the oscillations of tissue concentrations of oxyhemoglobin (O) and deoxyhemoglobin (D) into components due to blood volume (subscript V) and blood flow (subscript F): O=OV+OF, D=DV+DF. This is achieved by setting the phase angle Arg(OF)-Arg(O), which can be estimated by a hemodynamic model that we recently developed. We found this angle to be -72 deg for the cardiac pulsation at 1 Hz, and -7 deg for paced breathing at 0.1 Hz. Setting this angle, we can obtain the oxygen saturation of hemoglobin of the volume-oscillating vascular compartment, SV=|OV|/(|OV|+|DV|). We demonstrate this approach with cerebral near-infrared spectroscopy measurements on healthy volunteers at rest (n=4) and during 0.1 Hz paced breathing (n=3) with a 24-channel system. Rest data at the cardiac frequency were used to calculate the arterial saturation, S(a); over all subjects and channels, we found ==0.96±0.02. In the case of paced breathing, we found =0.66±0.14, which reflects venous-dominated hemodynamics at the respiratory frequency.

  14. Merging Static and Dynamic Depth Cues with Optical-Flow Recovery for Creating Stereo Videos

    Directory of Open Access Journals (Sweden)

    Fang-Hsuan Cheng

    2013-01-01

    Full Text Available A method for estimating the depth information of a general monocular image sequence and then creating a 3D stereo video is proposed. Distinguishing between foreground and background is possible without additional information, and then foreground pixels are moved to create the binocular image. The proposed depth estimation method is based on coarse-to-fine strategy. By applying the CID method in the spatial domain, the sharpness and the contrast of an image can be improved by the distance of the region based on its color. Then a coarse depth map of the image can be generated. An optical-flow method based on temporal information is then used to search and compare the block motion status between previous and current frames, and then the distance of the block can be estimated according to the amount of block motion. Finally, the static and motion depth information is integrated to create the fine depth map. By shifting foreground pixels based on the depth information, a binocular image pair can be created. A sense of 3D stereo can be obtained without glasses by an autostereoscopic 3D display.

  15. Unmanned Aerial Vehicle Navigation Using Wide-Field Optical Flow and Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Matthew B. Rhudy

    2015-01-01

    Full Text Available This paper offers a set of novel navigation techniques that rely on the use of inertial sensors and wide-field optical flow information. The aircraft ground velocity and attitude states are estimated with an Unscented Information Filter (UIF and are evaluated with respect to two sets of experimental flight data collected from an Unmanned Aerial Vehicle (UAV. Two different formulations are proposed, a full state formulation including velocity and attitude and a simplified formulation which assumes that the lateral and vertical velocity of the aircraft are negligible. An additional state is also considered within each formulation to recover the image distance which can be measured using a laser rangefinder. The results demonstrate that the full state formulation is able to estimate the aircraft ground velocity to within 1.3 m/s of a GPS receiver solution used as reference “truth” and regulate attitude angles within 1.4 degrees standard deviation of error for both sets of flight data.

  16. Primate-inspired vehicle navigation using optic flow and mental rotations

    Science.gov (United States)

    Arkin, Ronald C.; Dellaert, Frank; Srinivasan, Natesh; Kerwin, Ryan

    2013-05-01

    Robot navigation already has many relatively efficient solutions: reactive control, simultaneous localization and mapping (SLAM), Rapidly-Exploring Random Trees (RRTs), etc. But many primates possess an additional inherent spatial reasoning capability: mental rotation. Our research addresses the question of what role, if any, mental rotations can play in enhancing existing robot navigational capabilities. To answer this question we explore the use of optical flow as a basis for extracting abstract representations of the world, comparing these representations with a goal state of similar format and then iteratively providing a control signal to a robot to allow it to move in a direction consistent with achieving that goal state. We study a range of transformation methods to implement the mental rotation component of the architecture, including correlation and matching based on cognitive studies. We also include a discussion of how mental rotations may play a key role in understanding spatial advice giving, particularly from other members of the species, whether in map-based format, gestures, or other means of communication. Results to date are presented on our robotic platform.

  17. Characterization of zebrafish larvae suction feeding flow using μPIV and optical coherence tomography

    Science.gov (United States)

    Pekkan, Kerem; Chang, Brian; Uslu, Fazil; Mani, Karthick; Chen, Chia-Yuan; Holzman, Roi

    2016-07-01

    The hydrodynamics of suction feeding is critical for the survival of fish larvae; failure to capture food during the onset of autonomous feeding can rapidly lead to starvation and mortality. Fluid mechanics experiments that investigate the suction feeding of suspended particles are limited to adult fishes, which operate at large Reynolds numbers. This manuscript presents the first literature results in which the external velocity fields generated during suction feeding of early zebrafish larvae (2500-20,000 μm total length) are reported using time-resolved microscopic particle image velocimetry. For the larval stages studied, the maximum peak suction velocity of the inflow bolus is measured at a finite distance from the mouth tip and ranges from 1 to 8 mm/s. The average pressure gradient and the velocity profile proximal to the buccal (mouth) cavity are calculated, and two distinct trends are identified. External recirculation regions and reverse flow feeding cycles are also observed and quantified. One of the unresolved questions in fish suction feeding is the shape and dynamics of the buccal cavity during suction feeding; optical coherence tomography imaging is found to be useful for reconstructing the mouth kinematics. The projected area of the mouth cavity during the feeding cycle varies up to 160 and 22 % for the transverse and mid-sagittal planes, respectively. These findings can inspire novel hydrodynamically efficient biomedical and microfluidic devices.

  18. Design of Jitter Compensation Algorithm for Robot Vision Based on Optical Flow and Kalman Filter

    Directory of Open Access Journals (Sweden)

    B. R. Wang

    2014-01-01

    Full Text Available Image jitters occur in the video of the autonomous robot moving on bricks road, which will reduce robot operation precision based on vision. In order to compensate the image jitters, the affine transformation kinematics were established for obtaining the six image motion parameters. The feature point pair detecting method was designed based on Eigen-value of the feature windows gradient matrix, and the motion parameters equation was solved using the least square method and the matching point pairs got based on the optical flow. The condition number of coefficient matrix was proposed to quantificationally analyse the effect of matching errors on parameters solving errors. Kalman filter was adopted to smooth image motion parameters. Computing cases show that more point pairs are beneficial for getting more precise motion parameters. The integrated jitters compensation software was developed with feature points detecting in subwindow. And practical experiments were conducted on two mobile robots. Results show that the compensation costing time is less than frame sample time and Kalman filter is valid for robot vision jitters compensation.

  19. Spatial attention is attracted in a sustained fashion toward singular points in the optic flow.

    Directory of Open Access Journals (Sweden)

    Shuo Wang

    Full Text Available While a single approaching object is known to attract spatial attention, it is unknown how attention is directed when the background looms towards the observer as s/he moves forward in a quasi-stationary environment. In Experiment 1, we used a cued speeded discrimination task to quantify where and how spatial attention is directed towards the target superimposed onto a cloud of moving dots. We found that when the motion was expansive, attention was attracted towards the singular point of the optic flow (the focus of expansion, FOE in a sustained fashion. The effects were less pronounced when the motion was contractive. The more ecologically valid the motion features became (e.g., temporal expansion of each dot, spatial depth structure implied by distribution of the size of the dots, the stronger the attentional effects. Further, the attentional effects were sustained over 1000 ms. Experiment 2 quantified these attentional effects using a change detection paradigm by zooming into or out of photographs of natural scenes. Spatial attention was attracted in a sustained manner such that change detection was facilitated or delayed depending on the location of the FOE only when the motion was expansive. Our results suggest that focal attention is strongly attracted towards singular points that signal the direction of forward ego-motion.

  20. An optical flow-based integrated navigation system inspired by insect vision.

    Science.gov (United States)

    Pan, Chao; Deng, He; Yin, Xiao Fang; Liu, Jian Guo

    2011-10-01

    Some insects use optic flow (OF) to perform their navigational tasks perfectly. Learning from insects' OF navigation strategies, this article proposes a bio-inspired integrated navigation system based on OF. The integrated navigation system is composed of an OF navigation system (OFNS) and an OF aided navigation system (OFAN). The OFNS uses a simple OF method to measure motion at each step along a path. The position information is then obtained by path integration. However, path integration leads to cumulative position errors which increase rapidly with time. To overcome this problem, the OFAN is employed to assist the OFNS in estimating and correcting these cumulative errors. The OFAN adopts an OF-based Kalman filter (KF) to continuously estimate the position errors. Moreover, based on the OF technique used in the OFNS, we develop a new OF method employed by the OFAN to generate the measurement input of the OF-based KF. As a result, both the OFNS and the OFAN in our integrated navigation system are derived from the same OF method so that they share input signals and some operations. The proposed integrated navigation system can provide accurate position information without interference from cumulative errors yet doing so with low computational effort. Simulations and comparisons have demonstrated its efficiency.

  1. 3D Viscoelastic Finite Element Modelling of Polymer Flow in the Fiber Drawing Process for Microstructured Polymer Optical Fiber Fabrication

    DEFF Research Database (Denmark)

    Fasano, Andrea; Rasmussen, Henrik K.; Marín, J. M. R.

    2015-01-01

    The process of drawing an optical fiber from a polymer preform is still not completely understood,although it represents one of the most critical steps in the process chain for the fabrication of microstructuredpolymer optical fibers (mPOFs). Here we present a new approach for the numerical...... the numerical modelling of mPOF drawing has mainly beenbased on principles, such as generalized Newtonian fluid dynamics, which are not able to cope with the elasticcomponent in polymer flow. In the present work, we employ the K-BKZ constitutive equation, a non-linearsingle-integral model that combines both...

  2. In-vivo imaging of blood flow in human retinal vessels using color Doppler optical coherence tomography

    Science.gov (United States)

    Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

    1999-04-01

    Quantification of retinal blood flow may lead to a better understanding of the progression and treatment of several ocular disorders, including diabetic retinopathy, age- related macular degeneration, and glaucoma. Current techniques, such as fluorescein angiography and laser Doppler velocimetry are limited, failing to provide sufficient information to the clinician. Color Doppler optical coherence tomography (CDOCT) is a novel technique using coherent heterodyne detection for simultaneous cross- sectional imaging of tissue microstructure and blood flow. This technique is capable of high spatial and velocity resolution imaging in highly scattering media. We implemented CDOCT for retinal blood flow mapping in human subjects. No dilation of the pupil was necessary. CDOCT is demonstrated for determining bidirectional flow in sub- 100micrometers diameter vessels in the retina. Additionally, we calculated Doppler broadening using the variance of depth- resolved spectra to identify regions with large velocity gradients within the Xenopus heart. This technique may be useful in quantifying local tissue perfusion in highly vascular retinal tissue.

  3. Design of fan beam optical sensor and its application in mass flow rate measurement of pneumatically conveyed solids

    Institute of Scientific and Technical Information of China (English)

    LI Yang; ZHENG Ying-na; YUE Hong-wei

    2005-01-01

    The fan-beam optical sensor is made up of many semiconductor lasers and detectors fixed around the wall alternately at a cross section of pneumatically conveying pipe. When the sensor works, a scanning light source emits a 50° lamellar fan-beam through the gas-solid two phase flow, and the projection data resulting extinction effect of solid particles are detected at the same time. With the projection data, the flow rate mass can be calculated, and then the flow image can be reconstructed. In this paper, the design of the sensor including spatial arrangement of the structural parts, basic principle and measurement sensitivity distribution are introduced. The mathematical measurement model of solid mass flow rate is presented together with the testing results.

  4. Impact of intraocular pressure on changes of blood flow in the retina, choroid, and optic nerve head in rats investigated by optical microangiography.

    Science.gov (United States)

    Zhi, Zhongwei; Cepurna, William O; Johnson, Elaine C; Morrison, John C; Wang, Ruikang K

    2012-09-01

    In this paper, we demonstrate the use of optical coherence tomography/optical microangiography (OCT/OMAG) to image and measure the effects of acute intraocular pressure (IOP) elevation on retinal, choroidal and optic nerve head (ONH) perfusion in the rat eye. In the experiments, IOP was elevated from 10 to 100 mmHg in 10 mmHg increments. At each IOP level, three-dimensional data volumes were captured using an ultrahigh sensitive (UHS) OMAG scanning protocol for 3D volumetric perfusion imaging, followed by repeated B-scans for Doppler OMAG analysis to determine blood flow velocity. Velocity and vessel diameter measurements were used to calculate blood flow in selected retinal blood vessels. Choroidal perfusion was calculated by determining the peripapillary choroidal filling at each pressure level and calculating this as a percentage of area filling at baseline (10 mmHg). ONH blood perfusion was calculated as the percentage of blood flow area over a segmented ONH area to a depth 150 microns posterior to the choroidal opening. We show that volumetric blood flow reconstructions revealed detailed 3D maps, to the capillary level, of the retinal, choroidal and ONH microvasculature, revealing retinal arterioles, capillaries and veins, the choroidal opening and a consistent presence of the central retinal artery inferior to the ONH. While OCT structural images revealed a reversible compression of the ONH and vasculature with elevated IOP, OMAG successfully documented changes in retinal, choroidal and ONH blood perfusion and allowed quantitative measurements of these changes. Starting from 30 mm Hg, retinal blood flow (RBF) diminished linearly with increasing IOP and was nearly extinguished at 100 mm Hg, with full recovery after return of IOP to baseline. Choroidal filling was unaffected until IOP reached 60 mmHg, then decreased to 20% of baseline at IOP 100 mmHg, and normalized when IOP returned to baseline. A reduction in ONH blood perfusion at higher IOP's was also

  5. Reconstruction of three-dimensional occluded object using optical flow and triangular mesh reconstruction in integral imaging.

    Science.gov (United States)

    Jung, Jae-Hyun; Hong, Keehoon; Park, Gilbae; Chung, Indeok; Park, Jae-Hyeung; Lee, Byoungho

    2010-12-06

    We proposed a reconstruction method for the occluded region of three-dimensional (3D) object using the depth extraction based on the optical flow and triangular mesh reconstruction in integral imaging. The depth information of sub-images from the acquired elemental image set is extracted using the optical flow with sub-pixel accuracy, which alleviates the depth quantization problem. The extracted depth maps of sub-image array are segmented by the depth threshold from the histogram based segmentation, which is represented as the point clouds. The point clouds are projected to the viewpoint of center sub-image and reconstructed by the triangular mesh reconstruction. The experimental results support the validity of the proposed method with high accuracy of peak signal-to-noise ratio and normalized cross-correlation in 3D image recognition.

  6. Local motion compensation in image sequences degraded by atmospheric turbulence: a comparative analysis of optical flow vs. block matching methods

    Science.gov (United States)

    Huebner, Claudia S.

    2016-10-01

    As a consequence of fluctuations in the index of refraction of the air, atmospheric turbulence causes scintillation, spatial and temporal blurring as well as global and local image motion creating geometric distortions. To mitigate these effects many different methods have been proposed. Global as well as local motion compensation in some form or other constitutes an integral part of many software-based approaches. For the estimation of motion vectors between consecutive frames simple methods like block matching are preferable to more complex algorithms like optical flow, at least when challenged with near real-time requirements. However, the processing power of commercially available computers continues to increase rapidly and the more powerful optical flow methods have the potential to outperform standard block matching methods. Therefore, in this paper three standard optical flow algorithms, namely Horn-Schunck (HS), Lucas-Kanade (LK) and Farnebäck (FB), are tested for their suitability to be employed for local motion compensation as part of a turbulence mitigation system. Their qualitative performance is evaluated and compared with that of three standard block matching methods, namely Exhaustive Search (ES), Adaptive Rood Pattern Search (ARPS) and Correlation based Search (CS).

  7. A new methodology for pixel-quantitative precipitation nowcasting using a pyramid Lucas Kanade optical flow approach

    Science.gov (United States)

    Liu, Yu; Xi, Du-Gang; Li, Zhao-Liang; Hong, Yang

    2015-10-01

    Short-term high-resolution Quantitative Precipitation Nowcasting (QPN) has important implications for navigation, flood forecasting, and other hydrological and meteorological concerns. This study proposes a new algorithm called Pixel-based QPN using the Pyramid Lucas-Kanade Optical Flow method (PPLK), which comprises three steps: employing a Pyramid Lucas-Kanade Optical Flow method (PLKOF) to estimate precipitation advection, projecting rainy clouds by considering the advection and evolution pixel by pixel, and interpolating QPN imagery based on the space-time continuum of cloud patches. The PPLK methodology was evaluated with 2338 images from the geostationary meteorological satellite Fengyun-2F (FY-2F) of China and compared with two other advection-based methods, i.e., the maximum correlation method and the Horn-Schunck Optical Flow scheme. The data sample covered all intensive observations since the launch of FY-2F, despite covering a total of only approximately 10 days. The results show that the PPLK performed better than the algorithms used for comparison, demonstrating less time expenditure, more effective cloud tracking, and improved QPN accuracy.

  8. Research on non rigid registration algorithm of DCE-MRI based on mutual information and optical flow

    Science.gov (United States)

    Yu, Shihua; Wang, Rui; Wang, Kaiyu; Xi, Mengmeng; Zheng, Jiashuo; Liu, Hui

    2015-07-01

    Image matching plays a very important role in the field of medical image, while the two image registration methods based on the mutual information and the optical flow are very effective. The experimental results show that the two methods have their prominent advantages. The method based on mutual information is good for the overall displacement, while the method based on optical flow is very sensitive to small deformation. In the breast DCE-MRI images studied in this paper, there is not only overall deformation caused by the patient, but also non rigid small deformation caused by respiratory deformation. In view of the above situation, the single-image registration algorithms cannot meet the actual needs of complex situations. After a comprehensive analysis to the advantages and disadvantages of these two methods, this paper proposes a registration algorithm of combining mutual information with optical flow field, and applies subtraction images of the reference image and the floating image as the main criterion to evaluate the registration effect, at the same time, applies the mutual information between image sequence values as auxiliary criterion. With the test of the example, this algorithm has obtained a better accuracy and reliability in breast DCE-MRI image sequences.

  9. Intrathoracic tumour motion estimation from CT imaging using the 3D optical flow method

    Science.gov (United States)

    Guerrero, Thomas; Zhang, Geoffrey; Huang, Tzung-Chi; Lin, Kang-Ping

    2004-09-01

    The purpose of this work was to develop and validate an automated method for intrathoracic tumour motion estimation from breath-hold computed tomography (BH CT) imaging using the three-dimensional optical flow method (3D OFM). A modified 3D OFM algorithm provided 3D displacement vectors for each voxel which were used to map tumour voxels on expiration BH CT onto inspiration BH CT images. A thoracic phantom and simulated expiration/inspiration BH CT pairs were used for validation. The 3D OFM was applied to the measured inspiration and expiration BH CT images from one lung cancer and one oesophageal cancer patient. The resulting displacements were plotted in histogram format and analysed to provide insight regarding the tumour motion. The phantom tumour displacement was measured as 1.20 and 2.40 cm with full-width at tenth maximum (FWTM) for the distribution of displacement estimates of 0.008 and 0.006 cm, respectively. The maximum error of any single voxel's motion estimate was 1.1 mm along the z-dimension or approximately one-third of the z-dimension voxel size. The simulated BH CT pairs revealed an rms error of less than 0.25 mm. The displacement of the oesophageal tumours was nonuniform and up to 1.4 cm, this was a new finding. A lung tumour maximum displacement of 2.4 cm was found in the case evaluated. In conclusion, 3D OFM provided an accurate estimation of intrathoracic tumour motion, with estimated errors less than the voxel dimension in a simulated motion phantom study. Surprisingly, oesophageal tumour motion was large and nonuniform, with greatest motion occurring at the gastro-oesophageal junction. Presented at The IASTED Second International Conference on Biomedical Engineering (BioMED 2004), Innsbruck, Austria, 16-18 February 2004.

  10. Deformation analysis of 3D tagged cardiac images using an optical flow method

    Directory of Open Access Journals (Sweden)

    Gorman Robert C

    2010-03-01

    Full Text Available Abstract Background This study proposes and validates a method of measuring 3D strain in myocardium using a 3D Cardiovascular Magnetic Resonance (CMR tissue-tagging sequence and a 3D optical flow method (OFM. Methods Initially, a 3D tag MR sequence was developed and the parameters of the sequence and 3D OFM were optimized using phantom images with simulated deformation. This method then was validated in-vivo and utilized to quantify normal sheep left ventricular functions. Results Optimizing imaging and OFM parameters in the phantom study produced sub-pixel root-mean square error (RMS between the estimated and known displacements in the x (RMSx = 0.62 pixels (0.43 mm, y (RMSy = 0.64 pixels (0.45 mm and z (RMSz = 0.68 pixels (1 mm direction, respectively. In-vivo validation demonstrated excellent correlation between the displacement measured by manually tracking tag intersections and that generated by 3D OFM (R ≥ 0.98. Technique performance was maintained even with 20% Gaussian noise added to the phantom images. Furthermore, 3D tracking of 3D cardiac motions resulted in a 51% decrease in in-plane tracking error as compared to 2D tracking. The in-vivo function studies showed that maximum wall thickening was greatest in the lateral wall, and increased from both apex and base towards the mid-ventricular region. Regional deformation patterns are in agreement with previous studies on LV function. Conclusion A novel method was developed to measure 3D LV wall deformation rapidly with high in-plane and through-plane resolution from one 3D cine acquisition.

  11. Expanding hot flow in the black hole binary SWIFT J1753.5-0127: evidence from optical timing

    Science.gov (United States)

    Veledina, Alexandra; Gandhi, Poshak; Hynes, Robert; Kajava, Jari J. E.; Tsygankov, Sergey S.; Revnivtsev, Michail G.; Durant, Martin; Poutanen, Juri

    2017-09-01

    We describe the evolution of optical and X-ray temporal characteristics during the outburst decline of the black hole X-ray binary SWIFT J1753.5-0127. The optical/X-ray cross-correlation function demonstrates a single positive correlation at the outburst peak, then it has multiple dips and peaks during the decline stage, which are then replaced by the precognition dip plus peak structure in the outburst tail. Power spectral densities and phase lags show a complex evolution, revealing the presence of intrinsically connected optical and X-ray quasi-periodic oscillations. For the first time, we quantitatively explain the evolution of these timing properties during the entire outburst within one model, the essence of which is the expansion of the hot accretion flow towards the tail of the outburst. The pivoting of the spectrum produced by synchrotron Comptonization in the hot flow is responsible for the appearance of the anticorrelation with the X-rays and for the optical quasi-periodic oscillations. Our model reproduces well the cross-correlation and phase lag spectrum during the decline stage, which could not be understood with any model proposed before.

  12. Expanding hot flow in the black hole binary SWIFT J1753.5-0127: evidence from optical timing

    CERN Document Server

    Veledina, A; Hynes, R; Kajava, J J E; Tsygankov, S S; Revnivtsev, M G; Durant, M; Poutanen, J

    2016-01-01

    We describe the evolution of optical and X-ray temporal characteristics during the outburst decline of the black hole X-ray binary SWIFT J1753.5-0127. The optical/X-ray cross-correlation function demonstrates a single positive correlation at the outburst peak, then it has multiple dips and peaks during the decline stage, which are then replaced by the precognition dip plus peak structure in the outburst tail. Power spectral densities and phase lags show a complex evolution, revealing the presence of intrinsically connected optical and X-ray quasi-periodic oscillations. For the first time, we quantitatively explain the evolution of these timing properties during the entire outburst within one model, the essence of which is the expansion of the hot accretion flow towards the tail of the outburst. The pivoting of the spectrum produced by synchrotron Comptonization in the hot flow is responsible for the appearance of the anti-correlation with the X-rays and for the optical quasi-periodic oscillations. Our model r...

  13. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  14. Molecular-Based Optical Measurement Techniques for Transition and Turbulence in High-Speed Flow

    Science.gov (United States)

    Bathel, Brett F.; Danehy, Paul M.; Cutler, Andrew D.

    2013-01-01

    photogrammetry (for model attitude and deformation measurement) are excluded to limit the scope of this report. Other physical probes such as heat flux gauges, total temperature probes are also excluded. We further exclude measurement techniques that require particle seeding though particle based methods may still be useful in many high speed flow applications. This manuscript details some of the more widely used molecular-based measurement techniques for studying transition and turbulence: laser-induced fluorescence (LIF), Rayleigh and Raman Scattering and coherent anti-Stokes Raman scattering (CARS). These techniques are emphasized, in part, because of the prior experience of the authors. Additional molecular based techniques are described, albeit in less detail. Where possible, an effort is made to compare the relative advantages and disadvantages of the various measurement techniques, although these comparisons can be subjective views of the authors. Finally, the manuscript concludes by evaluating the different measurement techniques in view of the precision requirements described in this chapter. Additional requirements and considerations are discussed to assist with choosing an optical measurement technique for a given application.

  15. Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data

    Science.gov (United States)

    Hicks, A. K.; Mushotzky, R.

    2006-01-01

    We have analyzed XMM-Newton Optical Monitor (OM) UV (180-400 nm) data for a sample of 33 galaxies. 30 are cluster member galaxies, and nine of these are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates which span a range of 8 - 525 Solar Mass/yr. By comparing the ratio of UV to 2MASS J band fluxes, we find a significant UV excess in many, but not all, cooling flow CCGs, a finding consistent with the outcome of previous studies based on optical imaging data (McNamara & O'Connell 1989; Cardiel, Gorgas, & Aragon-Salamanca 1998; Crawford et al. 1999). This UV excess is a direct indication of the presence of young massive stars, and therefore recent star formation, in these galaxies. Using the Starburst99 spectral energy distribution (SED) model of continuous star formation over a 900 Myr period, we derive star formation rates of 0.2 - 219 solar Mass/yr for the cooling flow sample. For 2/3 of this sample it is possible to equate Chandra/XMM cooling flow mass deposition rates with UV inferred star formation rates, for a combination of starburst lifetime and IMF slope. This is a pilot study of the well populated XMM UV cluster archive and a more extensive follow up study is currently underway.

  16. High-flow-velocity and shear-rate imaging by use of color Doppler optical coherence tomography.

    Science.gov (United States)

    van Leeuwen, T G; Kulkarni, M D; Yazdanfar, S; Rollins, A M; Izatt, J A

    1999-11-15

    Color Doppler optical coherence tomography (CDOCT) is capable of precise velocity mapping in turbid media. Previous CDOCT systems based on the short-time Fourier transform have been limited to maximum flow velocities of the order of tens of millimeters per second. We describe a technique, based on interference signal demodulation at multiple frequencies, to extend the physiological relevance of CDOCT by increasing the dynamic range of measurable velocities to hundreds of millimeters per second. The physiologically important parameter of shear rate is also derived from CDOCT measurements. The measured flow-velocity profiles and shear-rate distributions correlate very well with theoretical predictions. The multiple demodulation technique, therefore, may be useful to monitor blood flow in vivo and to identify regions with high and low shear rates.

  17. Perception of scene-relative object movement: Optic flow parsing and the contribution of monocular depth cues.

    Science.gov (United States)

    Warren, Paul A; Rushton, Simon K

    2009-05-01

    We have recently suggested that the brain uses its sensitivity to optic flow in order to parse retinal motion into components arising due to self and object movement (e.g. Rushton, S. K., & Warren, P. A. (2005). Moving observers, 3D relative motion and the detection of object movement. Current Biology, 15, R542-R543). Here, we explore whether stereo disparity is necessary for flow parsing or whether other sources of depth information, which could theoretically constrain flow-field interpretation, are sufficient. Stationary observers viewed large field of view stimuli containing textured cubes, moving in a manner that was consistent with a complex observer movement through a stationary scene. Observers made speeded responses to report the perceived direction of movement of a probe object presented at different depths in the scene. Across conditions we varied the presence or absence of different binocular and monocular cues to depth order. In line with previous studies, results consistent with flow parsing (in terms of both perceived direction and response time) were found in the condition in which motion parallax and stereoscopic disparity were present. Observers were poorer at judging object movement when depth order was specified by parallax alone. However, as more monocular depth cues were added to the stimulus the results approached those found when the scene contained stereoscopic cues. We conclude that both monocular and binocular static depth information contribute to flow parsing. These findings are discussed in the context of potential architectures for a model of the flow parsing mechanism.

  18. 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...

  19. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  20. Modulation of walking speed by changing optic flow in persons with stroke

    Directory of Open Access Journals (Sweden)

    Lamontagne Anouk

    2007-06-01

    Full Text Available Abstract Background Walking speed, which is often reduced after stroke, can be influenced by the perception of optic flow (OF speed. The present study aims to: 1 compare the modulation of walking speed in response to OF speed changes between persons with stroke and healthy controls and 2 investigate whether virtual environments (VE manipulating OF speed can be used to promote volitional changes in walking speed post stroke. Methods Twelve persons with stroke and 12 healthy individuals walked on a self-paced treadmill while viewing a virtual corridor in a helmet-mounted display. Two experiments were carried out on the same day. In experiment 1, the speed of an expanding OF was varied sinusoidally at 0.017 Hz (sine duration = 60 s, from 0 to 2 times the subject's comfortable walking speed, for a total duration of 5 minutes. In experiment 2, subjects were exposed to expanding OFs at discrete speeds that ranged from 0.25 to 2 times their comfortable speed. Each test trial was paired with a control trial performed at comfortable speed with matching OF. For each of the test trials, subjects were instructed to walk the distance within the same time as during the immediately preceding control trial. VEs were controlled by the CAREN-2 system (Motek. Instantaneous changes in gait speed (experiment 1 and the ratio of speed changes in the test trial over the control trial (experiment 2 were contrasted between the two groups of subjects. Results When OF speed was changing continuously (experiment 1, an out-of-phase modulation was observed in the gait speed of healthy subjects, such that slower OFs induced faster walking speeds, and vice versa. Persons with stroke displayed weaker (p 0.05, T-test. Conclusion Stroke affects the modulation of gait speed in response to changes in the perception of movement through different OF speeds. Nevertheless, the preservation of even a modest modulation enabled the persons with stroke to increase walking speed when

  1. Comparison of the molecular mass and optical properties of colored dissolved organic material in two rivers and coastal waters by flow field-flow fractionation.

    Science.gov (United States)

    Zanardi-Lamardo, Eliete; Clark, Catherine D; Moore, Cynthia A; Zika, Rod G

    2002-07-01

    Colored dissolved organic material (CDOM) is an important sunlight absorbing substance affecting the optical properties of natural waters. However, little is known about its structural and optical properties mainly due to its complex matrix and the limitation of the techniques available. A comparison of two southwestern Florida rivers [the Caloosahatchee River (CR) and the Shark River (SR)] was done in terms of molecular mass (MM) and diffusion coefficients (D). The novel technique Frit inlet/frit outlet-flow field-flow fractionation (FIFO-FIFFF) with absorbance and fluorescence detectors was used to determine these properties. The SR receives organic material from the Everglades. By contrast, the CR arises from Lake Okeechobee in central Florida, receiving anthropogenic inputs, farming runoff, and natural organics. Both rivers discharge to the Gulf of Mexico. Fluorescence identified, for both rivers, two different MM distributions in low salinity water samples: the first was centered at approximately 1.7 kDa (CR) and approximately 2 kDa (SR); the second centered at approximately 13 kDa for both rivers, which disappeared gradually in the river plumes to below detection limit in coastal waters. Absorbance detected only one MM distribution centered at approximately 2 kDa (CR) and 2.2-2.4 kDa (SR). Fluorescence in general peaked at a lower MM than absorbance, suggesting a different size distribution for fluorophores vs chromophores. A photochemical study showed that, after sunlight, irradiated freshwater samples have similar characteristics to more marine waters, including a shift in MM distribution of chromophores. The differences observed between the rivers in the optical characteristics, MM distributions, and D values suggest that the CDOM sources, physical, and photochemical degradation processes are different for these two rivers.

  2. Fast optical measurements and imaging of flow mixing: Fast optical measurements and imaging of temperature in combined fossil fuel and biomass/waste systems

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Soennik; Fateev, A.; Lindorff Nielsen, K.; Evseev, V.

    2012-02-15

    Project is focused on fast time-resolved infrared measurements of gas temperature and fast IR-imagining of flames in various combustion environments. The infrared spectrometer system was developed in the project for fast infrared spectral measurements on industrial scale using IR-fibre- optics. Fast time-and spectral-resolved measurements in 1.5-5.1 mu spectral range give information about flame characteristics like gas and particle temperatures, eddies and turbulent gas mixing. Time-resolved gas composition in that spectral range (H{sub 2}O, CH{sub 4}, CO{sub 2}, CO) which is one of the key parameters in combustion enhancement can be also obtained. The infrared camera was also used together with special endoscope optics for fast thermal imaging of a coal-straw flame in an industrial boiler. Obtained time-resolved infrared images provided useful information for the diagnostics of the flame and fuel distribustion. The applicability of the system for gas leak detection is also demonstrated. The infrared spectrometer system with minor developments was applied for fast time-resolved exhaust gas temperature measurements performed simultaneously at the three optical ports of the exhaust duct of a marine Diesel engine and visualisation of gas flow behaviour in cylinder. (Author)

  3. A fiber-optic water flow sensor based on laser-heated silicon Fabry-Pérot cavity

    Science.gov (United States)

    Liu, Guigen; Sheng, Qiwen; Resende Lisboa Piassetta, Geraldo; Hou, Weilin; Han, Ming

    2016-05-01

    A hot-wire fiber-optic water flow sensor based on laser-heated silicon Fabry-Pérot interferometer (FPI) has been proposed and demonstrated in this paper. The operation of the sensor is based on the convective heat loss to water from a heated silicon FPI attached to the cleaved enface of a piece of single-mode fiber. The flow-induced change in the temperature is demodulated by the spectral shifts of the reflection fringes. An analytical model based on the FPI theory and heat transfer analysis has been developed for performance analysis. Numerical simulations based on finite element analysis have been conducted. The analytical and numerical results agree with each other in predicting the behavior of the sensor. Experiments have also been carried to demonstrate the sensing principle and verify the theoretical analysis. Investigations suggest that the sensitivity at low flow rates are much larger than that at high flow rates and the sensitivity can be easily improved by increasing the heating laser power. Experimental results show that an average sensitivity of 52.4 nm/(m/s) for the flow speed range of 1.5 mm/s to 12 mm/s was obtained with a heating power of ~12 mW, suggesting a resolution of ~1 μm/s assuming a wavelength resolution of 0.05 pm.

  4. Blood flowing state analysis in outflow tract of chick embryonic heart based on spectral domain optical coherence tomography

    Science.gov (United States)

    Zhao, Yuqian; Suo, Yanyan; Liang, Chengbo; Ma, Zhenhe

    2016-03-01

    The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) and periodic stress (WPS) are the components which have been proved to influence the morphogenesis during early stages of cardiac development. The vessel wall will be deformed by the blood pressure and produce natural elastic force acting on the blood. Because blood flowing in different flow state and show different characteristics of fluid, which influence the calculation of WSS and WPS directly, it is necessary to study the blood flow state. In this paper, we introduce a method to quantify the blood flowing state of early stage chick embryonic heart based on high speed spectral domain optical coherence tomography (SDOCT).4D (x,y,z,t) scan was performed on the outflow tract (OFT) of HH18 (~3 days of incubation) chick embryonic heart. By processing the structural image, the geometric parameters were obtained. Blood flow velocity distribution in the OFT were calculated by Doppler OCT method. Hemodynamic parameters were obtained at different times during the cardiac cycle used biofluid mechanics theory, such as Reynolds number and Womersley number.

  5. Optic nerve atrophy

    Science.gov (United States)

    Optic atrophy; Optic neuropathy ... There are many causes of optic atrophy. The most common is poor blood flow. This is called ischemic optic neuropathy. The problem most often affects older adults. The optic ...

  6. Distributed measurement of flow rate in conduits using heated fiber optic distributed temperature sensing

    Science.gov (United States)

    Sánchez, Raúl; Zubelzu, Sergio; Rodríguez-Sinobas, Leonor; Juana, Luis

    2016-04-01

    In some cases flow varies along conduits, such as in irrigated land drainage pipes and channels, irrigation laterals and others. Detailed knowledge of flow rate along the conduit makes possible analytical evaluation of water distribution and collection systems performance. Flow rate can change continuously in some systems, like in drainage pipes and channels, or abruptly, like in conduits bifurcations or emitter insertions. A heat pulse along the conduit makes possible to get flow rate from continuity and heat balance equations. Due to the great value of specific heat of water, temperature changes along conduit are smaller than the noise that involves the measurement process. This work presents a methodology that, dealing with the noise of distributed temperature measurements, leads to flow rate determination along pressurized pipes or open channel flows.

  7. A gel-based skin and blood flow model for a Doppler optical coherence tomography (DOCT) imaging system

    Science.gov (United States)

    Lawlor, Kate; O'Connell, Marie-Louise; Jonathan, Enock; Leahy, Martin J.

    2010-02-01

    Since its discovery in 1842 by Christian Johann Doppler, the Doppler Effect has had many applications in the scientific world. In recent years, the phenomenon has been integrated with Optical Coherence Tomography (OCT) yielding Doppler Optical Coherence Tomography (DOCT), a technique that is useful for high-resolution imaging of the skin microcirculation. However, interpretation of DOCT images is rather challenging. Thus, our study aims to aid understanding of DOCT images with respect to parameters of microcirculation components such as blood vessel size, depth and angular position. To this end, we have constructed a gel-based tissue and blood-flow model for performing DOCT studies under well controlled conditions. We present results from a pilot study using a gel-based tissue and blood flow model. Human blood was pumped through the model at various velocities from a commercial calibrated syringe pump, serving as a standard reference point for all velocity measurements. The range of velocity values was chosen to coincide with that found in the human vasculature. Simultaneous DOCT imaging at different flow rates contributed to establishing the capabilities and limitations of the DOCT system under investigation. We present preliminary results as first step to developing a robust validation protocol with which to aid future research in this area.

  8. New optical sensing technique of tissue viability and blood flow based on nanophotonic iterative multi-plane reflectance measurements

    Directory of Open Access Journals (Sweden)

    Yariv I

    2016-10-01

    Full Text Available Inbar Yariv,1 Menashe Haddad,2,3 Hamootal Duadi,1 Menachem Motiei,1 Dror Fixler1 1Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, Israel; 2Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; 3Mayanei Hayeshua Medical Center, Benei Brak, Israel Abstract: Physiological substances pose a challenge for researchers since their optical properties change constantly according to their physiological state. Examination of those substances noninvasively can be achieved by different optical methods with high sensitivity. Our research suggests the application of a novel noninvasive nanophotonics technique, ie, iterative multi-plane optical property extraction (IMOPE based on reflectance measurements, for tissue viability examination and gold nanorods (GNRs and blood flow detection. The IMOPE model combines an experimental setup designed for recording light intensity images with the multi-plane iterative Gerchberg-Saxton algorithm for reconstructing the reemitted light phase and calculating its standard deviation (STD. Changes in tissue composition affect its optical properties which results in changes in the light phase that can be measured by its STD. We have demonstrated this new concept of correlating the light phase STD and the optical properties of a substance, using transmission measurements only. This paper presents, for the first time, reflectance based IMOPE tissue viability examination, producing a decrease in the computed STD for older tissues, as well as investigating their organic material absorption capability. Finally, differentiation of the femoral vein from adjacent tissues using GNRs and the detection of their presence within blood circulation and tissues are also presented with high sensitivity (better than computed tomography to low quantities of GNRs (<3 mg. Keywords: Gerchberg-Saxton, optical properties, gold nanorods, blood vessel, tissue viability

  9. Optical and Compositional Properties of SiO x Films Deposited by HFCVD: Effect of the Hydrogen Flow

    Science.gov (United States)

    Luna López, J. A.; Vázquez Valerdi, D. E.; Benítez Lara, A.; García Salgado, G.; Hernández-de la Luz, A. D.; Morales Sánchez, A.; Flores Gracia, F. J.; Dominguez, M. A.

    2017-04-01

    In this work, the effect of hydrogen flow and thermal annealing on the compositional and optical properties of non-stoichiometric silicon oxide (SiO x) films with embedded silicon nanocrystals is reported. The SiO x films are obtained by hot filament chemical vapor deposition technique at three different hydrogen flow levels, namely, 50 sccm, 100 sccm, and 150 sccm. The SiO x films are characterized by different techniques. It is found by x-ray photoelectron spectroscopy (XPS) that with increasing hydrogen flow, the SiO x films contain higher silicon (Si) concentration. When the hydrogen flow decreases, the absorption edge of the as-grown SiO x films, as obtained from the transmittance spectra, shifts from 300 nm to 500 nm, and this opens the possibility of band gap tuning. Increasing the hydrogen flow level in turn means that the SiO x films contain higher Si concentration, as confirmed by the XPS profile composition measured in the SiO x films. After thermal annealing, the SiO x films transmittance spectra showed a further shift of the absorption edge toward larger wavelengths. The Fourier transform infrared (FTIR) spectroscopy reveals film composition changes induced by the hydrogen flow variations. In addition, the FTIR spectra reveal the bands attributed to the hydrogen presence in the as-grown SiO x films. The bands become more intense with increasing hydrogen flow, but they rapidly disappear after the thermal annealing. The as-grown SiO x films exhibit wide band photoluminescence (PL) spectra with the main components at 688 nm, 750 nm, and 825 nm. The SiO x film deposited at 100 sccm hydrogen flow level shows the strongest PL intensity. According to PL results, the thermal annealing of the SiO x films generates the PL quenching in all samples due to hydrogen evaporation. The defects such as OH and Si-H groups in the as-grown SiOx films not only modify the optical band gap structure, but they also play the role of passivating non-radiative defects, which

  10. Optical visualisation of the flow around a cylinder in electrolyte under strong axial magnetic field.

    Science.gov (United States)

    Andreev, O.; Kobzev, A.; Kolesnikov, Yu.; Thess, A.

    Flows around obstacles are among the most common problems encountered in the fluid mechanics literature, and cylindrical obstacles definitely received the most extensive attention. The reason for this is that this relatively simple geometry already encompasses most of the important physical effects likely to play a role in flow around more complicated obstacles. This means that understanding the cylinder problem provides relevant insight on a wide variety of problem ranging from aerodynamics, with the flow around a wing or a vehicle, to pollutant dispersion around building, flows in turbines … When the working fluid conducts electricity additional effects are involved. In particular, the presence of a magnetic field tends to homogenise the flow in the direction of the magnetic field lines which leads to strong alterations of the flow patterns known from the classical nonconducting case. This configuration is also a very generic one as Magnetohydrodynamic flows around obstacle also occur in a wide variety of applications: for instance, the space vehicle re-entry problem features the flow of a conducting plasma around an obstacle: [1] and [2] have shown that it could be influenced by a strong magnetic field in order to reduce heat transfer. The cooling blanket of the future nuclear fusion reactor ITER soon to be built in France, features a complex flow of liquid metal in a very high magnetic field (typically 10 T), in which the occurrence of obstacles cannot be avoided.

  11. Numerical models and experiment of air flow in a simulation box for optical wireless communications

    Directory of Open Access Journals (Sweden)

    Latal Jan

    2016-01-01

    Full Text Available In this article, the authors focused on real measurements of mechanical turbulence generated by ventilators in the simulation box for Optical Wireless Communications. The mechanical turbulences disturb the optical beam that propagates along the central axis of the simulation box. The aim of authors is to show the effect of mechanical turbulence on optical beams at different heights in the simulation box. In the Ansys Fluent, we created numerical models which were then compared with real measurements. Authors compared the real and numerical models according to statistical methods.

  12. Development of a three-dimensional correction method for optical distortion of flow field inside a liquid droplet.

    Science.gov (United States)

    Gim, Yeonghyeon; Ko, Han Seo

    2016-04-15

    In this Letter, a three-dimensional (3D) optical correction method, which was verified by simulation, was developed to reconstruct droplet-based flow fields. In the simulation, a synthetic phantom was reconstructed using a simultaneous multiplicative algebraic reconstruction technique with three detectors positioned at the synthetic object (represented by the phantom), with offset angles of 30° relative to each other. Additionally, a projection matrix was developed using the ray tracing method. If the phantom is in liquid, the image of the phantom can be distorted since the light passes through a convex liquid-vapor interface. Because of the optical distortion effect, the projection matrix used to reconstruct a 3D field should be supplemented by the revision ray, instead of the original projection ray. The revision ray can be obtained from the refraction ray occurring on the surface of the liquid. As a result, the error on the reconstruction field of the phantom could be reduced using the developed optical correction method. In addition, the developed optical method was applied to a Taylor cone which was caused by the high voltage between the droplet and the substrate.

  13. Passive and electro-optic polymer photonics and InP electronics integration for multi-flow terabit transceivers at edge SDN switches and data-center gateways

    DEFF Research Database (Denmark)

    Avramopoulos, Hercules; Katopodis, V.; Groumas, P.

    2014-01-01

    Within PANTHER research project, we aim to develop multi-rate, multi-format, multi-reach and multi-flow terabit transceivers for data-center gateways, having the capability of flexibly controlling this enormous capacity and distributing it among independent optical flows. To this end, we combine ...

  14. Signal and depth enhancement for in vivo flow cytometer measurement of ear skin by optical clearing agents.

    Science.gov (United States)

    Ding, Yimin; Wang, Jing; Fan, Zhichao; Wei, Dan; Shi, Rui; Luo, Qingming; Zhu, Dan; Wei, Xunbin

    2013-01-01

    The in vivo flow cytometry (IVFC) has shown a great potential for detecting circulating tumor cells quantitatively in the bloodstream. However, the detection depth suffers from the strong light scattering of tissue. In this study, an innovative ear skin optical clearing agent (ESOCA) is employed to improve the signal quality of the IVFC. Our results show that compared with commonly used glycerol, topical application of ESOCA can enhance the transmittance of rat ear significantly in vivo. The labeled red blood cells can be detected by the IVFC with higher signal quality and greater detection depth. This study is very helpful for potential tumor metastasis studies by the IVFC in deep tissues.

  15. A computationally efficient autoregressive method for generating phase screens with frozen flow and turbulence in optical simulations

    CERN Document Server

    Srinath, Sriakr; Rudy, Alexander R; Ammons, S Mark

    2015-01-01

    We present a sample-based, autoregressive (AR) method for the generation and time evolution of atmospheric phase screens that is computationally efficient and uses a single parameter per Fourier mode to vary the power contained in the frozen flow and stochastic components. We address limitations of Fourier-based methods such as screen periodicity and low spatial frequency power content. Comparisons of adaptive optics (AO) simulator performance when fed AR phase screens and translating phase screens reveal significantly elevated residual closed-loop temporal power for small increases in added stochastic content at each time step, thus displaying the importance of properly modeling atmospheric "boiling". We present preliminary evidence that our model fits to AO telemetry are better reflections of real conditions than the pure frozen flow assumption.

  16. A Complete Optical Sensor System Based on a POF-SPR Platform and a Thermo-Stabilized Flow Cell for Biochemical Applications.

    Science.gov (United States)

    Cennamo, Nunzio; Chiavaioli, Francesco; Trono, Cosimo; Tombelli, Sara; Giannetti, Ambra; Baldini, Francesco; Zeni, Luigi

    2016-02-04

    An optical sensor platform based on surface plasmon resonance (SPR) in a plastic optical fiber (POF) integrated into a thermo-stabilized flow cell for biochemical sensing applications is proposed. This device has been realized and experimentally tested by using a classic receptor-analyte assay. For this purpose, the gold surface of the POF was chemically modified through the formation of a self-assembling monolayer. The surface robustness of the POF-SPR platform has been tested for the first time thanks to the flow cell. The experimental results show that the proposed device can be successfully used for label-free biochemical sensing. The final goal of this work is to achieve a complete, small-size, simple to use and low cost optical sensor system. The whole system with the flow cell and the optical sensor are extensively described, together with the experimental results obtained with an immunoglobulin G (IgG)/anti-IgG assay.

  17. A Complete Optical Sensor System Based on a POF-SPR Platform and a Thermo-Stabilized Flow Cell for Biochemical Applications

    Directory of Open Access Journals (Sweden)

    Nunzio Cennamo

    2016-02-01

    Full Text Available An optical sensor platform based on surface plasmon resonance (SPR in a plastic optical fiber (POF integrated into a thermo-stabilized flow cell for biochemical sensing applications is proposed. This device has been realized and experimentally tested by using a classic receptor-analyte assay. For this purpose, the gold surface of the POF was chemically modified through the formation of a self-assembling monolayer. The surface robustness of the POF-SPR platform has been tested for the first time thanks to the flow cell. The experimental results show that the proposed device can be successfully used for label-free biochemical sensing. The final goal of this work is to achieve a complete, small-size, simple to use and low cost optical sensor system. The whole system with the flow cell and the optical sensor are extensively described, together with the experimental results obtained with an immunoglobulin G (IgG/anti-IgG assay.

  18. Crank angle resolved flow field characterization of a heavy-duty one-cylinder optical engine

    Energy Technology Data Exchange (ETDEWEB)

    Van der Meyden, T.J.

    2009-03-15

    Soot and nitric oxide (NOx) production are the main negative aspects of Diesel combustion. This is why new combustion strategies are being investigated, such as Premixed Charge Compression Ignition (PCCI). PCCI is one of the most promising combustion strategies for internal combustion engines in the future, since PCCI combustion is able to realize very low soot and nitric oxide emissions. PCCI combines the efficiency of a diesel and the low particulate emission of an Otto engine. To achieve PCCI combustion with limited heat release rates, the influence of charge stratification on combustion should be investigated. In this work, the first steps to achieve that goal are made. The first step is to determine in-cylinder velocities by measuring flow fields using Particle Image Velocimetry (PIV). The test setup consists of a one-cylinder optically accessible heavy duty engine driven by an electrical motor. The upper part of the liner and piston bottom are both made of sapphire. For PIV measurements a 10 Hz Nd:YAG Continuum Surelite laser is used with pulse energies of 140 mJ. The used camera is a Kodak Megaplus ES 1.0 CCD with 1008 x 1018 pixels. The seeding particles are produced from silicon oil using Laskin nozzles and have a diameter of about 0.7 im. Pre- and post- processing and the evaluation of the recorded PIV images is done using the commercially available software program PIVview (Pivtec). The velocity analysis is done using the commercial software program Tecplot. More knowledge is gathered on the in-cylinder velocities, aimed at a future detailed study on the effect of charge stratification in PCCI combustion. Ensemble averaged velocities, vorticities and strain rates, turbulence intensities and turbulent kinetic energies as a function of the crank angle, engine speed, measurement height and compression ratio have been investigated. Velocity and turbulence appear to be proportional to the engine speed. The position of the ensemble averaged swirl center as a

  19. Effect of silane flow rate on structural, electrical and optical properties of silicon thin films grown by VHF PECVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Gope, Jhuma [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumar, Sushil, E-mail: skumar@nplindia.org [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Sudhakar, S.; Rauthan, C.M.S. [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, P.C. [Department of Physics, Banaras Hindu University, Varanasi 221005 (India)

    2013-08-15

    Hydrogenated silicon thin films deposited by VHF PECVD process for various silane flow rates have been investigated. The silane flow rate was varied from 5 sccm to 30 sccm, maintaining all other parameters constant. The electrical, structural and optical properties of these films were systematically studied as a function of silane flow rate. These films were characterized by Raman spectroscopy, Scanning Electron Microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and UV–visible (UV–Vis) spectroscopy. Different crystalline volume fraction (22%–60%) and band gap (∼1.58 eV–∼1.96 eV) were achieved for silicon thin films by varying the silane concentration. A transition from amorphous to nanocrystalline silicon has been confirmed by Raman and FTIR analysis. The film grown at this transition region shows the high conductivity in the order of 10{sup −4} Ω{sup −1} cm{sup −1}. - Highlights: • Silicon films grown using VHF PECVD at various F{sub silane} (silane flow rate). • Amorphous to nanocrystalline silicon transition at F{sub silane} ∼5 sccm–10 sccm. • Deposition rate increases with the increase of F{sub silane}. • Powder formation occurred beyond 20 sccm of F{sub silane}. • Film grown at 20 sccm shows max. crystalline fraction ∼60% with E{sub g} ∼1.58 eV.

  20. Low gas flow inductively coupled plasma optical emission spectrometry for the analysis of food samples after microwave digestion.

    Science.gov (United States)

    Nowak, Sascha; Gesell, Monika; Holtkamp, Michael; Scheffer, Andy; Sperling, Michael; Karst, Uwe; Buscher, Wolfgang

    2014-11-01

    In this work, the recently introduced low flow inductively coupled plasma optical emission spectrometry (ICP-OES) with a total argon consumption below 0.7 L/min is applied for the first time to the field of food analysis. One goal is the investigation of the performance of this low flow plasma compared to a conventional ICP-OES system when non-aqueous samples with a certain matrix are introduced into the system. For this purpose, arsenic is determined in three different kinds of fish samples. In addition several nutrients (K, Na, Mg, Ca) and trace metals (Co, Cu, Mn, Cd, Pb, Zn, Fe, and Ni) are determined in honey samples (acacia) after microwave digestion. The precision of the measurements is characterized by relative standard deviations (RSD) and compared to the corresponding precision values achieved using the conventional Fassel-type torch of the ICP. To prove the accuracy of the low flow ICP-OES method, the obtained data from honey samples are validated by a conventional ICP-OES. For the measurements concerning arsenic in fish, the low flow ICP-OES values are validated by conventional Fassel-type ICP-OES. Furthermore, a certified reference material was investigated with the low gas flow setup. Limits of detection (LOD), according to the 3σ criterion, were determined to be in the low microgram per liter range for all analytes. Recovery rates in the range of 96-106% were observed for the determined trace metal elements. It was proven that the low gas flow ICP-OES leads to results that are comparable with those obtained with the Fassel-type torch for the analysis of food samples.

  1. Improved optical techniques for studying sonic and supersonic injection into Mach 3 flow

    Science.gov (United States)

    Buggele, Alvin E.; Seasholtz, Richard G.

    1997-11-01

    Filtered Rayleigh Scattering and shadowgraph flow visualization were used to characterize the penetration of helium or moist air injected transversely at several pressures to a Mach 3 flow in the NASA Lewis 3.81 inch by 10 inch continuous flow supersonic wind tunnel. This work is in support of the LOX augmented nuclear thermal rocket program. The present study used an injection-seeded, frequency doubled Nd:YAG pulsed laser to illuminate a transverse section of the injectant plume. Rayleigh scattered light was passed through an iodine absorption cell to suppress stray laser light and was imaged onto a cooled CCD camera. The scattering was based on condensation of water vapor in the injectant flow. Results are presented for various configurations of sonic and supersonic injector designs mounted primarily in the floor of the tunnel. Injectors studied include a single 0.25 inch diameter hole, five 0.112 inch diameter holes on 0.177 inch spacing, and a 7 degree half angle wedge. High speed shadowgraph flow visualization images were obtained with several video camera systems. Roof and floor static pressure data are presented several ways for the three configurations of injection designs with and without helium and/or air injection into Mach 3 flow.

  2. Effects of support surface and optic flow on step-like movements in pre-crawling and crawling infants.

    Science.gov (United States)

    Anderson, David I; Kobayashi, Yuka; Hamel, Kate; Rivera, Monica; Campos, Joseph J; Barbu-Roth, Marianne

    2016-02-01

    Step-like movements were examined in pre-crawling (n=9) and crawling (n=9) 6-13 month-old infants in the air and on a surface in response to a static pattern or optic flows that moved toward or away from the infant. Infants completed six 60-s trials. A significant interaction between locomotor status and support condition revealed that pre-crawling infants made more step-like movements in the air than on a rigid surface. In contrast, crawling infants made an equivalent number of step-like movements in the air and on the surface. Optic flow did not influence the number of step-like movements made by infants. The pre-crawling infant finding is consistent with a finding in a previous study in which two month-old infants were shown to step more in the air than on the ground. This finding is discussed relative to the idea that the infant stepping pattern disappears because the legs become too heavy to lift.

  3. Effects of Support Surface and Optic Flow on Step-Like Movements in Pre-crawling and Crawling Infants

    Science.gov (United States)

    Anderson, David I.; Kobayashi, Yuka; Hamel, Kate; Rivera, Monica; Campos, Joseph J.; Barbu-Roth, Marianne

    2016-01-01

    Step-like movements were examined in pre-crawling (n=9) and crawling (n=9) 6–13 month-old infants in the air and on a surface in response to a static pattern or optic flows that moved toward or away from the infant. Infants completed six 60-second trials. A significant interaction between locomotor status and support condition revealed that pre-crawling infants made more step-like movements in the air than on a rigid surface. In contrast, crawling infants made an equivalent number of step-like movements in the air and on the surface. Optic flow did not influence the number of step-like movements made by infants. The pre-crawling infant finding is consistent with a finding in a previous study in which two month-old infants were shown to step more in the air than on the ground. This finding is discussed relative to the idea that the infant stepping pattern disappears because the legs become too heavy to lift. PMID:26773774

  4. An in situ optical imaging system for measuring lipid uptake, vessel contraction, and lymph flow in small animal lymphatic vessels

    Science.gov (United States)

    Kassis, Timothy; Weiler, Michael J.; Dixon, J. Brandon

    2012-03-01

    All dietary lipids are transported to venous circulation through the lymphatic system, yet the underlying mechanisms that regulate this process remain unclear. Understanding how the lymphatics functionally respond to changes in lipid load is important in the diagnosis and treatment of lipid and lymphatic related diseases such as obesity, hypercholesterolemia, and lymphedema. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. A custom-built optical set-up provides us with the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. This is achieved by dividing the light path into two optical bands. Utilizing high-speed and back-illuminated CCD cameras and post-acquisition image processing algorithms, we have the potential quantify correlations between vessel contraction, lymph flow and lipid concentration of mesenteric lymphatic vessels in situ. Local flow velocity is measured through lymphocyte tracking, vessel contraction through measurements of the vessel walls and lipid uptake through fluorescence intensity tracking of a fluorescent long chain fatty acid analogue, Bodipy FL C16. This system will prove to be an invaluable tool for both scientists studying lymphatic function in health and disease, and those investigating strategies for targeting the lymphatic system with orally delivered drugs.

  5. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    Science.gov (United States)

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

  6. Design and performance evaluation of an OpenFlow-based control plane for software-defined elastic optical networks with direct-detection optical OFDM (DDO-OFDM) transmission.

    Science.gov (United States)

    Liu, Lei; Peng, Wei-Ren; Casellas, Ramon; Tsuritani, Takehiro; Morita, Itsuro; Martínez, Ricardo; Muñoz, Raül; Yoo, S J B

    2014-01-13

    Optical Orthogonal Frequency Division Multiplexing (O-OFDM), which transmits high speed optical signals using multiple spectrally overlapped lower-speed subcarriers, is a promising candidate for supporting future elastic optical networks. In contrast to previous works which focus on Coherent Optical OFDM (CO-OFDM), in this paper, we consider the direct-detection optical OFDM (DDO-OFDM) as the transport technique, which leads to simpler hardware and software realizations, potentially offering a low-cost solution for elastic optical networks, especially in metro networks, and short or medium distance core networks. Based on this network scenario, we design and deploy a software-defined networking (SDN) control plane enabled by extending OpenFlow, detailing the network architecture, the routing and spectrum assignment algorithm, OpenFlow protocol extensions and the experimental validation. To the best of our knowledge, it is the first time that an OpenFlow-based control plane is reported and its performance is quantitatively measured in an elastic optical network with DDO-OFDM transmission.

  7. LES/RANS Modeling of Aero-Optical Effects in a Supersonic Cavity Flow

    Science.gov (United States)

    2016-06-13

    disturbances create eddy shocklets that propagate into the free-stream and create additional optical path disturbances. 15. SUBJECT TERMS 16. SECURITY ...Proceedings of the third AFOSR International Conference on DNS /LES, 2000 [19] Sirovich, L. “Turbulence and the dynamics of coherent structures.” I—III

  8. Laser-optical and numerical Research of the flow inside the lubricating gap of a journal bearing model

    Science.gov (United States)

    Nobis, M.; Stücke, P.; Schmidt, M.; Riedel, M.

    2013-04-01

    The laser-optical research of the flow inside the lubricating gap of a journal bearing model is one important task in a larger overall project. The long-term objective is the development of an easy-to-work calculation tool which delivers information about the causes and consequences of cavitation processes in hydrodynamically lubricated journal bearings. Hence, it will be possible to find statements for advantageous and disadvantageous geometrical shapes of the bushings. In conclusion such a calculation tool can provide important insights for the construction and design of future journal bearings. Current design programs are based on a two-dimensional approach for the lubricating gap. The first dimension is the breath of the bearing and the second dimension is the circumferential direction of the bearing. The third dimension, the expansion of the gap in radial direction, will be neglected. Instead of an exact resolution of the flow pattern inside the gap, turbulence models are in use. Past studies on numerical and experimental field have shown that inside the lubricating gap clearly organized and predominantly laminar flow structures can be found. Thus, for a detailed analysis of the reasons and effects of cavitation bubbles, a three-dimensional resolution of the lubricating gap is inevitable. In addition to the qualitative evaluation of the flow with visualization experiments it is possible to perform angle-based velocity measurements inside the gap with the help of a triggered Laser-Doppler- Velocimeter (LDV). The results of these measurements are used to validate three-dimensional CFD flow simulations, and to optimize the numerical mesh structure and the boundary conditions. This paper will present the experimental setup of the bearing model, some exemplary results of the visualization experiments and LDV measurements as well as a comparison between experimental and numerical results.

  9. Quantification of volumetric cerebral blood flow using hybrid laser speckle contract and optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Valim, Niksa; Dunn, Andrew K.

    2016-03-01

    Studying neurovascular blood flow function in cerebrovascular activities requires accurate visualization and characterization of blood flow volume as well as the dynamics of blood cells in microcirculation. In this study, we present a novel integration of laser speckle contrast imaging (LSCI) and spectral domain optical coherence tomography (SD-OCT) for rapid volumetric imaging of blood flow in cortical capillaries. LSCI uses the illumination of wide-field near infrared light (NIR) and monitors back scattered light to characterize the relative dynamics of blood flow in microcirculation. Absolute measurement of blood cells and blood volume requires high-resolution volumetric structural information. SD-OCT system uses coherence gating to measure scattered light from a small volume within high structural resolution. The structural imaging system rapidly assesses large number of capillaries for spatio-temporal tracking of red blood cells (RBC). A very fast-ultra resolution SD-OCT system was developed for imaging high-resolution volumetric samples. The system employed an ultra wideband light source (1310 ± 200 nm in wavelength) corresponding to an axial resolution of 3 micrometers in tissue. The spectrometer of the SD-OCT was customized for a maximum scanning rate of 147,000 line/s. We demonstrated a fast volumetric OCT angiography algorithm to visualize large numbers of vessels in a 2-mm deep sample volume. A LSCI system that has been developed previously in our group was integrated to the imaging system for the characterization of dynamic blood cells. The conjunction data from LSCI and SD-OCT systems imply the feasibility of accurate quantification of absolute cortical blood flow.

  10. Scattering of inhomogeneous circularly polarized optical field and mechanical manifestation of the internal energy flows

    CERN Document Server

    Bekshaev, A Ya; Hanson, S G; Zenkova, C Yu

    2012-01-01

    Basing on the Mie theory and on the incident beam model via superposition of two plane waves, we analyze numerically the momentum flux of the field scattered by a spherical microparticle placed within the spatially inhomogeneous circularly polarized paraxial light beam. The asymmetry between the forward- and backward-scattered momentum fluxes in the Rayleigh scattering regime is revealed that appears due to the spin part of the internal energy flow in the incident beam. The transverse ponderomotive forces exerted on dielectric and conducting particles of different sizes are calculated, and special features of the mechanical actions produced by the spin and orbital parts of the internal energy flow have been recognized. In particular, the transverse orbital flow exerts on a subwavelength particle the transverse force that grows as a^3 for conducting and as a^6 for dielectric particle with radius a, in compliance with the dipole mechanism of the field-particle interaction; the force associated with the spin flo...

  11. Blood flow contrast enhancement in optical coherence tomography using microbubbles: a phantom study

    Science.gov (United States)

    Assadi, Homa; Demidov, Valentin; Karshafian, Raffi; Douplik, Alexandre; Vitkin, I. Alex

    2016-03-01

    In this study gas microbubbles are investigated as intravascular OCT contrast agents. Agar+Intralipid scattering tissue-like phantoms with two embedded microtubes were fabricated to model vascular blood flow. One was filled with human blood, and the other with a mixture of human blood and microbubbles. Swept-source structural and speckle variance OCT images, as well as speckle decorrelation times, were evaluated under both stationary and flow conditions. Faster decorrelation times and higher image contrast were detected in the presence of microbubbles in all experiments, and the effect was largest for speckle variance OCT ~2.3x greater contrast under flow conditions. The feasibility of utilizing microbubbles for tissue hemodynamic investigations and for microvasculature contrast enhancement in OCT angiography thus appears promising.

  12. Ultrasensitive flow sensing of a single cell using graphene-based optical sensors.

    Science.gov (United States)

    Xing, Fei; Meng, Gui-Xian; Zhang, Qian; Pan, Lei-Ting; Wang, Peng; Liu, Zhi-Bo; Jiang, Wen-Shuai; Chen, Yongsheng; Tian, Jian-Guo

    2014-06-11

    On the basis of the polarization-dependent absorption of graphene under total internal reflection, we designed a graphene-based optical refractive index sensor with high resolution of 1.7 × 10(-8) and sensitivity of 4.3 × 10(7) mV/RIU, as well as an extensive dynamic range. This highly sensitive graphene optical sensor enables label-free, live-cell, and highly accurate detection of a small quantity of cancer cells among normal cells at the single-cell level and the simultaneous detection and distinction of two cell lines without separation. It provides an accurate statistical distribution of normal and cancer cells with fewer cells. This facile and highly sensitive sensing refractive index may expand the practical applications of the biosensor.

  13. Towards an Automatic Parking System using Bio-Inspired 1-D Optical Flow Sensors

    OpenAIRE

    2015-01-01

    International audience; Although several (semi-) automatic parking systems have been presented throughout the years [1]–[12], car manufacturers are still looking for low-cost sensors providing redundant information about the obstacles around the vehicle, as well as efficient methods of processing this information, in the hope of achieving a very high level of robustness. We therefore investigated how Local Motion Sensors (LMSs) [13], [14], comprising only of a few pixels giving 1-D optical fl...

  14. Simultaneous thermal and optical imaging of two-phase flow in a micro-model

    NARCIS (Netherlands)

    Karadimitriou, N.K.; Nuske, P.; Kleingeld, P.J.; Hassanizadeh, S.M.; Helmig, R.

    2014-01-01

    In the study of non-equilibrium heat transfer in multiphase flow in porous media, parameters and constitutive relations, like heat transfer coefficients between phases, are unknown. In order to study the temperature development of a relatively hot invading immiscible non-wetting fluid and, ultimatel

  15. A new fibre-optic sensor for high-temperature flow measurement

    NARCIS (Netherlands)

    Schiferli, W.; Cheng, L.K.; Jansen, T.H.

    2012-01-01

    Measuring flow is essentia ìn the process and oil & gas ìndustry. In the oil and gas industry, orifice plates and vortex meters are popular, since their lack of moving parts makes them robust. However, the need for electronics limits maximum process temperatures to 150 to 200'C. Special electronics

  16. Miniaturized flow cytometer with 3D hydrodynamic particle focusing and integrated optical elements applying silicon photodiodes

    NARCIS (Netherlands)

    Rosenauer, M.; Buchegger, W.; Finoulst, I.; Verhaert, P.D.E.M.; Vellekoop, M.

    2010-01-01

    In this study, the design, realization and measurement results of a novel optofluidic system capable of performing absorbance-based flow cytometric analysis is presented. This miniaturized laboratory platform, fabricated using SU-8 on a silicon substrate, comprises integrated polymer-based waveguide

  17. Scattering of inhomogeneous circularly polarized optical field and mechanical manifestation of the internal energy flows

    DEFF Research Database (Denmark)

    Bekshaev, A. Ya; Angelsky, O. V.; Hanson, Steen Grüner

    2012-01-01

    Based on the Mie theory and on the incident beam model via superposition of two plane waves, we analyze numerically the momentum flux of the field scattered by a spherical, nonmagnetic microparticle placed within the spatially inhomogeneous circularly polarized paraxial light beam. The asymmetry...... flow in light fields....

  18. A TABU SEARCH APPROACH TOWARDS CONGESTION AND TOTAL FLOW MINIMIZATION IN OPTICAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Valter BOLJUN(C)I(C); Darko SKORIN-KAPOV; Jadranka SKORIN-KAPOV

    2004-01-01

    This paper considers rearrangeable multihop lightwave networks whereby each network node is equipped with a number p of transmitters and receivers, and a spectrum of wavelengths is accessible by, and shared among, all nodes by using the Wavelength Division Multiplexing (WDM). Depending on input traffic flow, nodal transmitters and receivers can be re-tuned to create virtual connectivity best suited with respect to a given optimization criterion. We present an efficient heuristic algorithm that combines two criteria for optimization: throughput maximization, as well as total flow minimization. Throughput maximization criterion is equivalent to congestion minimization, while minimizing total flow under the assumption of having links with equal lengths implies minimization of the average number of hops. Taking into account lengths of the links (i.e. link costs proportional with distances), the total flow minimization becomes equivalent to the total delay minimization. Tabu search is implemented as a two-phase strategy dealing with diversification as well as intensification of search. Computational experiments include consecutive runs with different sets of weights associated with the two criteria. Results for a benchmark set of problems are presented.

  19. Problem of Channel Utilization and Merging Flows in Buffered Optical Burst Switching Networks

    Directory of Open Access Journals (Sweden)

    Milos Kozak

    2013-01-01

    Full Text Available In the paper authors verify two problems of methods of operational research in optical burst switching. The first problem is at edge node, related to the medium access delay. The second problem is at an intermediate node related to buffering delay. A correction coefficient K of transmission speed is obtained from the first analysis. It is used in to provide a full-featured link of nominal data rate. Simulations of the second problem reveal interesting results. It is not viable to prepare routing and wavelength assignment based on end-to-end delay, i.e. link's length or number of hops, as commonly used in other frameworks (OCS, Ethernet, IP, etc. nowadays. Other parameters such as buffering probability must be taken into consideration as well. Based on the buffering probability an estimation of the number of optical/electrical converters can be made. This paper concentrates important traffic constraints of buffered optical burst switching. It allows authors to prepare optimization algorithms for regenerators placement in CAROBS networks using methods of operational research.

  20. A flowing liquid test system for assessing the linearity and time-response of rapid fibre optic oxygen partial pressure sensors.

    Science.gov (United States)

    Chen, R; Hahn, C E W; Farmery, A D

    2012-08-15

    The development of a methodology for testing the time response, linearity and performance characteristics of ultra fast fibre optic oxygen sensors in the liquid phase is presented. Two standard medical paediatric oxygenators are arranged to provide two independent extracorporeal circuits. Flow from either circuit can be diverted over the sensor under test by means of a system of rapid cross-over solenoid valves exposing the sensor to an abrupt change in oxygen partial pressure, P O2. The system is also capable of testing the oxygen sensor responses to changes in temperature, carbon dioxide partial pressure P CO2 and pH in situ. Results are presented for a miniature fibre optic oxygen sensor constructed in-house with a response time ≈ 50 ms and a commercial fibre optic sensor (Ocean Optics Foxy), when tested in flowing saline and stored blood.

  1. Calibration of soil moisture flow simulation models aided by the active heated fiber optic distributed temperature sensing AHFO

    Science.gov (United States)

    Rodriguez-Sinobas, Leonor; Zubelzu, Sergio; Sobrino, Fernando Fernando; Sánchez, Raúl

    2017-04-01

    Most of the studies dealing with the development of water flow simulation models in soils, are calibrated using experimental data measured by soil probe sensors or tensiometers which locate at specific points in the study area. However since the beginning of the XXI century, the use of Distributed Fiber Optic Temperature Measurement for estimating temperature variation along a cable of fiber optic has been assessed in multiple environmental applications. Recently, its application combined with an active heating pulses technique (AHFO) has been reported as a sensor to estimate soil moisture. This method applies a known amount of heat to the soil and monitors the temperature evolution, which mainly depends on the soil moisture content. Thus, it allows estimations of soil water content every 12.5 cm along the fiber optic cable, as long as 1500 m , with 2 % accuracy , every second. This study presents the calibration of a soil water flow model (developed in Hydrus 2D) with the AHFO technique. The model predicts the distribution of soil water content of a green area irrigated by sprinkler irrigation. Several irrigation events have been evaluated in a green area located at the ETSI Agronómica, Agroalimentaria y Biosistemas in Madrid where an installation of 147 m of fiber optic cable at 15 cm depth is deployed. The Distribute Temperature Sensing unit was a SILIXA ULTIMA SR (Silixa Ltd, UK) and has spatial and temporal resolution of 0.29 m. Data logged in the DTS unit before, during and after the irrigation event were used to calibrate the estimations in the Hydrus 2D model during the infiltration and redistribution of soil water content within the irrigation interval. References: Karandish, F., & Šimůnek, J. (2016). A field-modeling study for assessing temporal variations of soil-water-crop interactions under water-saving irrigation strategies. Agricultural Water Management, 178, 291-303. Li, Y., Šimůnek, J., Jing, L., Zhang, Z., & Ni, L. (2014). Evaluation of

  2. The effect of Al content, substrate temperature and nitrogen flow rate on optical band gap and optical features of nanostructured TiAlN thin films prepared by reactive magnetron sputtering

    Science.gov (United States)

    Jalali, Reza; Parhizkar, Mojtaba; Bidadi, Hassan; Naghshara, Hamid; Hosseini, Seyd Reza; Jafari, Majid

    2016-11-01

    In the present work, TiAlN thin films were prepared by using a dual reactive magnetron sputtering system on fused quartz substrates kept at room temperature and 400 °C; keeping nitrogen flow at 0.51 and 2.78 sccm, various DC and RF powers and the effect of these factors have been studied on the optical properties of the layers. The optical properties including absorption and transmission were studied by a UV-Visible spectrophotometer in the wavelength region (200-1100) nm. By plotting ( αhν)2 and ( αhν)1/2 versus the photon energy hυ, the optical band gap was evaluated. Experimental results show that layers with high percentage of aluminum and nitrogen have higher gap with respect to layers having high titanium percentage. TiAlN thin films deposited with 2.78 sccm nitrogen flow rate possess optical direct band gap in the range of 3.8-5.1 eV and optical indirect band gap in the range of 1.1-3.4 eV. The variation of optical band gap of the films that deposited on the substrate with 400 °C and nitrogen flow rate of 2.78 sccm was different from other layers.

  3. Fine sediment dynamics in unsteady open-channel flow studied with acoustic and optical systems

    Science.gov (United States)

    Bagherimiyab, Fereshteh; Lemmin, Ulrich

    2012-09-01

    In order to simulate fine sediment dynamics over an armored bed in a tidal river, unsteady accelerating, then steady open-channel flow over a movable (but not moving) coarse gravel bed (D50=5.5 mm) was studied. A layer of fine sediment (D50=120 μm) was placed on the coarse gravel bed. The thickness of the fine sediment layer on the gravel bed was varied between 4 and 6 mm, but it was found that the thickness of the layer had no effect on the results. Quasi-instantaneous profiles of velocity and sediment concentration were taken simultaneously and co-located. An Acoustic Doppler Velocity Profiler (ADVP) was combined with Particle Tracking Velocimetry (PTV) for suspended sediment particle tracking. Measurements resolved turbulence scales. During the final phase of the accelerating flow range, fine sediment suspension from the bed started in packets and rapidly created a ripple pattern that remained nearly stationary. Thereafter, vortex shedding produced most of the sediment suspension into the water column in the form of events or packets, making suspension intermittent. Simultaneously, sediment particles rolled along the bed following the ripple structure, thus slowly advancing the ripple pattern in the direction of the flow without altering ripple geometry. Fine sediment particles and hydrogen bubbles were used individually or combined as flow tracers in the acoustic measurements. When used individually, hydrogen bubbles provided full depth flow and backscattering information, whereas sediment particles traced only the lower layers of the flow, indicating sediment suspension. When both tracers were combined, hydrogen bubbles could only be distinguished from sediment particles when results at two different acoustic carrier frequencies were compared. The intermittency was observed in the backscattering of the acoustic system. The event structure in fine sediment suspension is seen by the PTV method. PTV velocity vectors varied in speed and orientation, were

  4. Analysis of whole blood samples with low gas flow inductively coupled plasma-optical emission spectrometry.

    Science.gov (United States)

    Nowak, Sascha; Künnemeyer, Jens; Terborg, Lydia; Trümpler, Stefan; Günsel, Andreas; Wiesmüller, Gerhard A; Karst, Uwe; Buscher, Wolfgang

    2015-01-01

    Low gas flow ICP-OES with a total argon consumption below 0.7 L/min is introduced for the analysis of trace elements in blood samples to investigate the influence of samples containing an organic solvent in a demanding matrix on the performance of this plasma for the first time. Therefore, gadolinium was determined in human plasma samples and mercury in red blood cells, human plasma, and precipitated plasma protein fraction. Limits of detection (LOD) were determined to be in the low microgram per liter range for the analytes and the accuracy of the method was assessed by comparison with a conventional Fassel-type torch-based ICP-OES. It was proven that the low gas flow ICP-OES leads to comparable results with the instrument based on the Fassel-type torch.

  5. A laboratory demonstration of an LQG technique for correcting frozen flow turbulence in adaptive optics systems

    CERN Document Server

    Rudy, Alexander; Srinath, Srikar; Ammons, S Mark; Gavel, Donald

    2015-01-01

    We present the laboratory verification of a method for re- moving the effects of frozen-flow atmospheric turbulence using a Linear Quadratic Gaussian (LQG) controller, also known as a Kalman Filter. This method, which we term "Predictive Fourier Control," can identify correlated atmospheric motions due to layers of frozen flow turbulence, and can predictively remove the effects of these correlated motions in real-time. Our laboratory verification suggests a factor of 3 improvement in the RMS residual wavefront error and a 10% improvement in measured Strehl of the system. We found that the RMS residual wavefront error was suppressed from 35.0 nm to 11.2 nm due to the use of Predictive Fourier Control, and that the far field Strehl improved from 0.479 to 0.520.

  6. Optical characterization of bubbly flows with a near-critical-angle scattering technique

    Energy Technology Data Exchange (ETDEWEB)

    Onofri, Fabrice R.A.; Krzysiek, Mariusz [IUSTI, UMR, CNRS, University of Provence, Polytech' DME, Technopole Chateau-Gombert, Marseille (France); Mroczka, Janusz [CEPM, Technical University of Wroclaw, Wroclaw (Poland); Ren, Kuan-Fang [CORIA, UMR, CNRS, University of Rouen, Saint-Etienne-du-Rouvray (France); Radev, Stefan [IMECH, Bulgarian Academy of Sciences, Sofia (Bulgaria); Bonnet, Jean-Philippe [M2P2, UMR, CNRS, University Paul Cezanne, Aix-en-Provence (France)

    2009-10-15

    The newly developed critical angle refractometry and sizing technique (CARS) allows simultaneous and instantaneous characterization of the local size distribution and the relative refractive index (i.e. composition) of a cloud of bubbles. The paper presents the recent improvement of this technique by comparison of different light scattering models and inversion procedures. Experimental results carried in various air/water and air/water-ethanol bubbly flows clearly demonstrate the efficiency and the potential of this technique. (orig.)

  7. Velocity measurements of low Reynolds number tube flow using fiber-optic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, J.C.

    1993-03-01

    In 1988 Nielsen started work to measure the spatial variability of the mass flux vector being transported in a porous medium. To measure the spatial variability of the mass flux vector, the spatial variability of its components(velocity, concentration) must be measured. Nielsen was successful in measuring the pore level concentration at many different pores and in verifying the assumption that a nonuniform concentration field exists within the mixing zone between two miscible fluids. However, Nielsen was unable to conduct the necessary pore level velocity measurements needed. Nielsen's work is being continued and a probe is being developed that will measure both velocity and concentration components at pore level. The probe is essentially the same probe used to make the pore level concentration measurements with added capabilities needed to make the velocity measurements. This probe has several design variables, dealing primarily with the velocity component, that need further investigation. The research presented in this thesis investigates these parameters by performing experiments in a capillary tube. The tube is a controlled system where the velocity of the fluid can be determined from the volumetric flow rate using Poiseuille's solution for viscous flow. Also, a statistically based relationship between the velocity measured with the probe and the velocity determined from the volumetric flow rate has been developed.

  8. Velocity measurements of low Reynolds number tube flow using fiber-optic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, J. Christopher [Univ. of Vermont, Burlington, VT (United States)

    1993-03-01

    In 1988 Nielsen started work to measure the spatial variability of the mass flux vector being transported in a porous medium. To measure the spatial variability of the mass flux vector, the spatial variability of its components(velocity, concentration) must be measured. Nielsen was successful in measuring the pore level concentration at many different pores and in verifying the assumption that a nonuniform concentration field exists within the mixing zone between two miscible fluids. However, Nielsen was unable to conduct the necessary pore level velocity measurements needed. Nielsen`s work is being continued and a probe is being developed that will measure both velocity and concentration components at pore level. The probe is essentially the same probe used to make the pore level concentration measurements with added capabilities needed to make the velocity measurements. This probe has several design variables, dealing primarily with the velocity component, that need further investigation. The research presented in this thesis investigates these parameters by performing experiments in a capillary tube. The tube is a controlled system where the velocity of the fluid can be determined from the volumetric flow rate using Poiseuille`s solution for viscous flow. Also, a statistically based relationship between the velocity measured with the probe and the velocity determined from the volumetric flow rate has been developed.

  9. Studies of complex terrain wind flows using acoustic sounder and optical cross-wind remote sensors

    Energy Technology Data Exchange (ETDEWEB)

    Porch, W.M.; Neff, W.; King, C.

    1985-08-01

    Remote sensing instrumentation has played an important role in the Atmospheric Studies in Complex Terrain (ASCOT) field experimental program. The goal of this program is to better understand transport and diffusion processes in complex terrain with an emphasis focused on nighttime drainage wind conditions. Two aspects of the instrumentation are discussed in this paper: acoustic sounders (doppler and monostatic) and space averaging optical cross-wind sensors. Data from these two sources are discussed and compared with data from conventional tower and tethersonde instrumentation. 13 refs., 10 figs. (WRF)

  10. Local mechanisms for the separation of optic flow-field components in the land crab, Cardisoma guanhumi: a role for motion parallax?

    Science.gov (United States)

    Johnson, Aaron P; Barnes, W Jon P; Macauley, Martin W S

    2004-01-01

    Although a number of global mechanisms have been proposed over the years that explain how crabs might separate the rotational and translational components of their optic flow field, there has been no evidence to date that local mechanisms such as motion parallax are used in this separation. We describe here a study that takes advantage of a recently developed suite of computer-generated visual stimuli that creates a three-dimensional world surrounding the crab in which we can simulate translational and rotational optic flow. We show that, while motion parallax is not the only mechanism used in flow-field separation, it does play a role in the recognition of translational optic flow fields in that, under conditions of low overall light intensity and low contrast ratio when crabs find the distinction between rotation and translation harder, smaller eye movements occur in response to translation when motion parallax cues are present than when they are absent. Thus, motion parallax is one of many cues that crabs use to separate rotational and translational optic flow by showing compensatory eye movements to only the former.

  11. A multisyringe flow injection method for the automated determination of sulfide in waters using a miniaturised optical fiber spectrophotometer.

    Science.gov (United States)

    Ferrer, Laura; de Armas, Graciela; Miró, Manuel; Estela, José Manuel; Cerdà, Víctor

    2004-12-15

    In this paper, a fully software-controlled multisyringe flow injection (MSFIA) spectrophotometric system is proposed for the determination of sulfide in environmental and waste waters. The implementation of ancillary solenoid valves into the flow network allows a multitude of injection modalities to be explored, the selected modality being directly dependent on the aim of the assays. The multicommuted sandwich-type approach is introduced in this work as an efficient means to warrant high sensitivity for the particular assay with excellent repeatabilities and a considerable reagent saving. Moreover, a high injection frequency may be easily attained by carrying out a multiple injection modality during a single forward displacement of the piston driver bar. The interfacing of the robust and versatile multisyringe piston pump with an optical fiber plug-in spectrophotometer furnished with a light emitting diode enables the miniaturization of the flow analyzer, which is thus readily adaptable to in-situ and real-time monitoring schemes. The flow method is based on the coupling Fischer's reaction of sulfide with N,N-dimethyl-p-phenylenediamine in the presence of Fe(III) as oxidizing reagent in a 0.7M HCl medium. Careful selection of the physical and chemical variables enabled coefficients of variations better than 1.5% (n = 10) at the 1mgl(-1) level for both injection modalities. Dynamic working ranges of 0.2-2.0 and 0.5-5mgl(-1) sulfide for sandwich and multiple injection techniques, and detection limits of 0.09 and 0.15mgl(-1), respectively, were obtained. Furthermore, the sandwich modality featured an average slope of 0.43 +/- 0.02lmg(-1) calculated from 10 day-to-day calibration plots. This result reveals better sensitivity than other flowing stream methods described in the literature. The multiple injection technique allowed an improvement of the injection throughput up to 80h(-1), although a decrease of sensitivity was concomitantly observed (average slope of 0

  12. Design, analysis, and initial testing of a fiber-optic shear gage for three-dimensional, high-temperature flows

    Science.gov (United States)

    Orr, Matthew W.

    This investigation concerns the design, analysis, and initial testing of a new, two-component wall shear gage for 3D, high-temperature flows. This gage is a direct-measuring, non-nulling design with a round head surrounded by a small gap. Two flexure wheels are used to allow small motions of the floating head. Fiber-optic displacement sensors measure how far the polished faces of counterweights on the wheels move in relation to a fixed housing as the primary measurement system. No viscous damping was required. The gage has both fiber-optic instrumentation and strain gages mounted on the flexures for validation of the newer fiber optics. The sensor is constructed of Haynes RTM 230RTM, a high-temperature nickel alloy. The gage housing is made of 316 stainless steel. All components of the gage in pure fiber-optic form can survive to a temperature of 1073 K. The bonding methods of the backup strain gages limit their maximum temperature to 473 K. The dynamic range of the gage is from 0--500 Pa (0--10g) and higher shears can be measured by changing the floating head size. Extensive use of finite element modeling was critical to the design and analysis of the gage. Static structural, modal, and thermal analyses were performed on the flexures using the ANSYS finite element package. Static finite element analysis predicted the response of the flexures to a given load, and static calibrations using a direct force method confirmed these results. Finite element modal analysis results were within 16.4% for the first mode and within 30% for the second mode when compared with the experimentally determined modes. Vibration characteristics of the gage were determined from experimental free vibration data after the gage was subjected to an impulse. Uncertainties in the finished geometry make this level of error acceptable. A transient thermal analysis examined the effects of a very high heat flux on the exposed head of the gage. The 100,000 W/m2 heat flux used in this analysis is

  13. Optical-flow-based background-oriented schlieren technique for measuring a laser-induced underwater shock wave

    CERN Document Server

    Hayasaka, Keisuke; Liu, Tianshu; Kameda, Masaharu

    2016-01-01

    The background-oriented schlieren (BOS) technique with the physics-based optical flow method (OF-BOS) is developed for measuring the pressure field of a laser-induced underwater shock wave. Compared to BOS with the conventional cross-correlation method in PIV (called PIV-BOS), by using the OF-BOS, the displacement field generated by the small density gradient in water can be obtained at the spatial resolution of one vector per pixel. The corresponding density and pressure fields can be further extracted. It is particularly demonstrated that the sufficiently high spatial resolution of the extracted displacement vector field is required in the tomographic reconstruction to correctly infer the pressure field of the spherical underwater shock wave. The capability of the OF-BOS is critically evaluated based on synchronized hydrophone measurements. Special emphasis is placed on direct comparison between the OF-BOS with the PIV-BOS.

  14. Optical-flow-based background-oriented schlieren technique for measuring a laser-induced underwater shock wave

    Science.gov (United States)

    Hayasaka, Keisuke; Tagawa, Yoshiyuki; Liu, Tianshu; Kameda, Masaharu

    2016-12-01

    The background-oriented schlieren (BOS) technique with the physics-based optical flow method (OF-BOS) is developed for measuring the pressure field of a laser-induced underwater shock wave. Compared to BOS with the conventional cross-correlation method that is also applied for particle image velocimetry (here called PIV-BOS), by using the OF-BOS, the displacement field generated by a small density gradient in water can be obtained at the spatial resolution of one vector per pixel. The corresponding density and pressure fields can be further extracted. It is demonstrated in particular that the sufficiently high spatial resolution of the extracted displacement vector field is required in the tomographic reconstruction to correctly infer the pressure field of the spherical underwater shock wave. The capability of the OF-BOS method is critically evaluated based on synchronized hydrophone measurements. Special emphasis is placed on direct comparison between the OF-BOS and PIV-BOS methods.

  15. Role of oxygen flow rate on the structural and optical properties of copper oxide thin films grown by reactive magnetron sputtering

    Science.gov (United States)

    Ali, M.; Gobinner, C. R.; Kekuda, D.

    2016-02-01

    Copper oxide thin films were grown by DC reactive magnetron sputtering. The structural investigation of the sputtered films was carried out using X-ray diffraction. The surface morphology of the films was observed through atomic force microscopy. A crossover in the crystalline phase from cuprous to cupric oxide (tenorite) was observed as a result of variation in the oxygen flow rate during sputtering. Deposition rate was also found to be a function of the oxygen flow rate, and it was found that the deposition rate decreased with an increase in the oxygen flow rate which could be attributed to the possible target oxidation at higher oxygen flow rates. Variation of grain size of the films with oxygen flow rate was analyzed through AFM analysis. Dependence of oxygen flow rate on the formation of two phases of copper oxide was also confirmed through the optical band gap measurements.

  16. Localized immunoassay in flow-through optical microbubble resonator (Conference Presentation)

    Science.gov (United States)

    Berneschi, Simone; Baldini, Francesco; Cosci, Alessandro; Cosi, Franco; Farnesi, Daniele; Nunzi Conti, Gualtiero; Tombelli, Sara; Trono, Cosimo; Pelli, Stefano; Giannetti, Ambra

    2016-05-01

    The integration of the Whispering Gallery Modes (WGMs) resonators in a microfluidics platform represents an important feature towards the realization of a compact high performance label-free biosensor. These hollow resonant microstructures present the advantage to combine the WGM resonator properties with the intrinsic capability of integrated microfluidics. In this sense, optical microbubble resonators (OMBRs), intended as a hollow core spherical bulge realized in a glass microcapillary by a suitable fabrication process, with their high Q factors (microfluidic parts completely inert from a biochemical point of view. The method is based on UV photoactivation, which allows to localize the biolayers only in correspondence of the OMBR inner wall. As a proof of concept, an immunoassay based on rabbit IgG/anti rabbit-IgG interaction was performed and. The anti rabbit-IgG antibody was labelled with Alexa Fluor 488 to verify, by a fluorescence characterization, the goodness of this procedure. Moreover, an anti mouse-IgG, labelled with the same fluorophore (Alexa Fluor 488) was used for specificity-tests of the IgG/anti-IgG interaction. The immunoassay based on fluorescence was characterized using an optical microscope (Zeiss AXIO inverted fluorescence microscope) working at the wavelengths of 470 nm for excitation of Alexa Fluor 488. The real time measurement of the resonance broadening after each functionalization step together with the high Q factor (< 105) measured after the IgG/anti-IgG interaction in water, gives a further proof for the method validity.

  17. Influence of oxygen flow rate on the structural, optical and electrical properties of ZnO films grown by DC magnetron sputtering

    Science.gov (United States)

    Gobbiner, Chaya Ravi; Ali Avanee Veedu, Muhammed; Kekuda, Dhananjaya

    2016-04-01

    Zinc oxide thin films were deposited on glass substrates at different oxygen flow rates by DC reactive magnetron sputtering. The oxygen flow rate was found to be one of the crucial parameters which influence structural, optical and electrical properties of grown films. The structural and optical characterization of the deposited films was carried out using X-ray diffraction and UV-visible spectroscopy, respectively. Swanepoel envelope and Drude-Lorentz (DL) models were applied to extract the optoelectronic parameters such as refractive index, dispersion energy and plasma frequency. Structurally, grain size was found to decrease with increase in oxygen flow rate during deposition. Moreover, all the films exhibited preferred (002) orientation confirming c-axis orientation of the films perpendicular to the substrate. For a particular range of oxygen flow rates, columnar growth was achieved. Marginal increase in the optical band gap from 3.14 to 3.22 eV was observed as the oxygen flow rate increased from 3 to 10 sccm. Calculated plasma frequency from the DL model was found to be in the infrared region. It has decreased as oxygen flow rate increased with the value from 1.625 × 1014 rad/s (862 cm-1) to 1.072 × 1014 rad/s (568 cm-1).

  18. Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling.

    Science.gov (United States)

    Vuong, Barry; Genis, Helen; Wong, Ronnie; Ramjist, Joel; Jivraj, Jamil; Farooq, Hamza; Sun, Cuiru; Yang, Victor X D

    2014-12-01

    Hemodynamics plays a critical role in the development of atherosclerosis, specifically in regions of curved vasculature such as bifurcations exhibiting irregular blood flow profiles. Carotid atherosclerotic disease can be intervened by stent implantation, but this may result in greater alterations to local blood flow and consequently further complications. This study demonstrates the use of a variant of Doppler optical coherence tomography (DOCT) known as split spectrum DOCT (ssDOCT) to evaluate hemodynamic patterns both before and after stent implantation in the bifurcation junction in the internal carotid artery (ICA). Computational fluid dynamics (CFD) models were constructed to simulate blood velocity profiles and compared to the findings achieved through ssDOCT images. Both methods demonstrated noticeable alterations in hemodynamic patterns following stent implantation, with features such as slow velocity regions at the neck of the bifurcation and recirculation zones at the stent struts. Strong correlation between CFD models and ssDOCT images demonstrate the potential of ssDOCT imaging in the optimization of stent implantation in the clinical setting.

  19. Thermal-Plume fibre Optic Tracking (T-POT test for flow velocity measurement in groundwater boreholes

    Directory of Open Access Journals (Sweden)

    T. Read

    2015-06-01

    Full Text Available We develop an approach for measuring in-well fluid velocities using point electrical heating combined with spatially and temporally continuous temperature monitoring using Distributed Temperature Sensing (DTS. The method uses a point heater to warm a discrete volume of water. The rate of advection of this plume, once the heating is stopped, equates to the average flow velocity in the well. We conducted Thermal-Plume fibre Optic Tracking (T-POT tests in a borehole in a fractured rock aquifer with the heater at the same depth and multiple pumping rates. Tracking of the thermal plume peak allowed the spatially varying velocity to be estimated up to 50 m downstream from the heating point, depending on the pumping rate. The T-POT technique can be used to estimate the velocity throughout long intervals provided that thermal dilution due to inflows, dispersion, or cooling by conduction do not render the thermal pulse unresolvable with DTS. A complete flow log may be obtained by deploying the heater at multiple depths, or with multiple point heaters.

  20. Diagnostics of two-phase flows with high concentration of a solid dispersed phase using fiber-optic sensors

    Science.gov (United States)

    Evseev, A. R.

    2016-10-01

    This paper is focused on the physical modeling of two-phase flows with high concentration of the dispersed phase. The fiber-optical sensors and their calibration procedure were developed for bubble concentration measurements in the fluidized bed apparatus (FB). Distributions of bubble concentration in the 2D and 3D FB apparatuses, which determine the quality of fluidization and local density of filling material, were obtained. The techniques of particle velocity and concentration measurements in the circulating fluidized bed (CFB) was developed using three-fiber sensor (the differential scheme of LDA) operated in backscattering regime. Sensor operation was analyzed and the main systematic measurement errors were determined; the original construction of the sensor was designed. The data on the velocity and concentration profiles of dispersed phase in a large-scale CFB apparatus were obtained for fluidization of particles by air. It was found that with increasing circulation velocity in the CFB apparatus, the particle concentration increases in the near-wall region much higher than in the flow core. The method of particle velocity measurements in a liquid was developed using the laser Doppler fiber anemometer (LDFA-1), operating in the backscattering regime. The signal to noise ratio was obtained for particles of different size and material in test measurements. The rates of consolidated precipitation of cryolite particles in a sedimentation apparatus with the inclined walls were measured.

  1. Flow-induced charge modulation in superfluid atomic fermions loaded into an optical kagome lattice.

    Science.gov (United States)

    Yamamoto, Daisuke; Sato, Chika; Nikuni, Tetsuro; Tsuchiya, Shunji

    2013-04-05

    We study the superfluid state of atomic fermions in a tunable optical kagome lattice motivated by recent experiments. We show that the imposed superflow induces spatial modulations in the density and order parameter of the pair condensate and leads to a charge modulated superfluid state analogous to a supersolid state. The spatial modulations in the superfluid emerge due to the geometric effect of the kagome lattice that introduces anisotropy in hopping amplitudes of fermion pairs in the presence of superflow. We also study superflow instabilities and find that the critical current limited by the dynamical instability is quite enhanced due to the large density of states associated with the flatband. The charge modulated superfluid state can sustain high temperatures close to the transition temperature that is also enhanced due to the flatband and is therefore realizable in experiments.

  2. Reconfigurable acquisition system with integrated optics for a portable flow cytometer

    Science.gov (United States)

    Kirleis, Matthew A.; Mathews, Scott A.; Verbarg, Jasenka; Erickson, Jeffrey S.; Piqué, Alberto

    2013-11-01

    Portable and inexpensive scientific instruments that are capable of performing point of care diagnostics are needed for applications such as disease detection and diagnosis in resource-poor settings, for water quality and food supply monitoring, and for biosurveillance activities in autonomous vehicles. In this paper, we describe the development of a compact flow cytometer built from three separate, customizable, and interchangeable modules. The instrument as configured in this work is being developed specifically for the detection of selected Centers for Disease Control (CDC) category B biothreat agents through a bead-based assay: E. coli O157:H7, Salmonella, Listeria, and Shigella. It has two-color excitation, three-color fluorescence and light scattering detection, embedded electronics, and capillary based flow. However, these attributes can be easily modified for other applications such as cluster of differentiation 4 (CD4) counting. Proof of concept is demonstrated through a 6-plex bead assay with the results compared to a commercially available benchtop-sized instrument.

  3. Reconfigurable acquisition system with integrated optics for a portable flow cytometer

    Energy Technology Data Exchange (ETDEWEB)

    Kirleis, Matthew A., E-mail: matthew.kirleis@nrl.navy.mil; Mathews, Scott A.; Verbarg, Jasenka; Erickson, Jeffrey S.; Piqué, Alberto [Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375 (United States)

    2013-11-15

    Portable and inexpensive scientific instruments that are capable of performing point of care diagnostics are needed for applications such as disease detection and diagnosis in resource-poor settings, for water quality and food supply monitoring, and for biosurveillance activities in autonomous vehicles. In this paper, we describe the development of a compact flow cytometer built from three separate, customizable, and interchangeable modules. The instrument as configured in this work is being developed specifically for the detection of selected Centers for Disease Control (CDC) category B biothreat agents through a bead-based assay: E. coli O157:H7, Salmonella, Listeria, and Shigella. It has two-color excitation, three-color fluorescence and light scattering detection, embedded electronics, and capillary based flow. However, these attributes can be easily modified for other applications such as cluster of differentiation 4 (CD4) counting. Proof of concept is demonstrated through a 6-plex bead assay with the results compared to a commercially available benchtop-sized instrument.

  4. Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps

    Science.gov (United States)

    Huang, Chong; Radabaugh, Jeffrey P.; Aouad, Rony K.; Lin, Yu; Gal, Thomas J.; Patel, Amit B.; Valentino, Joseph; Shang, Yu; Yu, Guoqiang

    2015-07-01

    Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning "1") for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89±0.15, 2.26±0.13, and 2.43±0.13 (mean±standard error), respectively, on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (pflap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flaps were 1.14 and 1.34, respectively, on postoperative days 2 and 4, indicating less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

  5. Transient MHD Free Convective Flow of an Optically Thick Gray Gas Past a Moving Vertical Plate in the Presence of Thermal Radiation and Mass Diffusion

    Directory of Open Access Journals (Sweden)

    S.K Ghosh

    2015-01-01

    Full Text Available The purpose of present investigation is to analyse bouyancy-driven radiation-convection flow past a moving vertical plate with reference to an optically dense medium in the presence of mass concentration, using Rosseland approximation permeated by a magnetic field. The flow is considered to be gray in the presence of free convection, mass transfer and radiation. An exact solution of the governing equations is obtained by applying the Laplace transform method. Numerical results of velocity distributions, shear stress, temperature distribution and mass concentration are presented graphically to give physical insight into the flow pattern.

  6. Steady flow and heat transfer analysis of Phan-Thein-Tanner fluid in double-layer optical fiber coating analysis with Slip Conditions

    Science.gov (United States)

    Khan, Zeeshan; Shah, Rehan Ali; Islam, Saeed; Jan, Bilal; Imran, Muhammad; Tahir, Farisa

    2016-10-01

    Modern optical fibers require double-layer coating on the glass fiber to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low-high density polyethylene (LDPE/HDPE), nylon and Polysulfone. In this paper, double-layer optical fiber coating is performed using melt polymer satisfying PTT fluid model in a pressure type die using wet-on-wet coating process. The assumption of fully developed flow of Phan-Thien-Tanner (PTT) fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die, where the fiber is dragged at a higher speed. The equations characterizing the flow and heat transfer phenomena are solved exactly and the effects of emerging parameters (Deborah and slip parameters, characteristic velocity, radii ratio and Brinkman numbers on the axial velocity, flow rate, thickness of coated fiber optics, and temperature distribution) are reported in graphs. It is shown that an increase in the non-Newtonian parameters increase the velocity in the absence or presence of slip parameters which coincides with related work. The comparison is done with experimental work by taking λ → 0 (non-Newtonian parameter).

  7. Simulator sickness when performing gaze shifts within a wide field of view optic flow environment: preliminary evidence for using virtual reality in vestibular rehabilitation

    Directory of Open Access Journals (Sweden)

    Whitney Susan L

    2004-12-01

    Full Text Available Abstract Background Wide field of view virtual environments offer some unique features that may be beneficial for use in vestibular rehabilitation. For one, optic flow information extracted from the periphery may be critical for recalibrating the sensory processes used by people with vestibular disorders. However, wide FOV devices also have been found to result in greater simulator sickness. Before a wide FOV device can be used in a clinical setting, its safety must be demonstrated. Methods Symptoms of simulator sickness were recorded by 9 healthy adult subjects after they performed gaze shifting tasks to locate targets superimposed on an optic flow background. Subjects performed 8 trials of gaze shifting on each of the six separate visits. Results The incidence of symptoms of simulator sickness while subjects performed gaze shifts in an optic flow environment was lower than the average reported incidence for flight simulators. The incidence was greater during the first visit compared with subsequent visits. Furthermore, the incidence showed an increasing trend over the 8 trials. Conclusion The performance of head unrestrained gaze shifts in a wide FOV optic flow environment is tolerated well by healthy subjects. This finding provides rationale for testing these environments in people with vestibular disorders, and supports the concept of using wide FOV virtual reality for vestibular rehabilitation.

  8. Steady flow and heat transfer analysis of Phan-Thein-Tanner fluid in double-layer optical fiber coating analysis with Slip Conditions

    Science.gov (United States)

    Khan, Zeeshan; Shah, Rehan Ali; Islam, Saeed; Jan, Bilal; Imran, Muhammad; Tahir, Farisa

    2016-01-01

    Modern optical fibers require double-layer coating on the glass fiber to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low-high density polyethylene (LDPE/HDPE), nylon and Polysulfone. In this paper, double-layer optical fiber coating is performed using melt polymer satisfying PTT fluid model in a pressure type die using wet-on-wet coating process. The assumption of fully developed flow of Phan-Thien-Tanner (PTT) fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die, where the fiber is dragged at a higher speed. The equations characterizing the flow and heat transfer phenomena are solved exactly and the effects of emerging parameters (Deborah and slip parameters, characteristic velocity, radii ratio and Brinkman numbers on the axial velocity, flow rate, thickness of coated fiber optics, and temperature distribution) are reported in graphs. It is shown that an increase in the non-Newtonian parameters increase the velocity in the absence or presence of slip parameters which coincides with related work. The comparison is done with experimental work by taking λ → 0 (non-Newtonian parameter). PMID:27708412

  9. First field demonstration of cloud datacenter workflow automation employing dynamic optical transport network resources under OpenStack and OpenFlow orchestration.

    Science.gov (United States)

    Szyrkowiec, Thomas; Autenrieth, Achim; Gunning, Paul; Wright, Paul; Lord, Andrew; Elbers, Jörg-Peter; Lumb, Alan

    2014-02-10

    For the first time, we demonstrate the orchestration of elastic datacenter and inter-datacenter transport network resources using a combination of OpenStack and OpenFlow. Programmatic control allows a datacenter operator to dynamically request optical lightpaths from a transport network operator to accommodate rapid changes of inter-datacenter workflows.

  10. In vivo functional imaging of blood flow and wall strain rate in outflow tract of embryonic chick heart using ultrafast spectral domain optical coherence tomography

    Science.gov (United States)

    Li, Peng; Yin, Xin; Shi, Liang; Rugonyi, Sandra; Wang, Ruikang K.

    2012-09-01

    During cardiac development, the cardiac wall and flowing blood are two important cardiac tissues that constantly interact with each other. This dynamic interaction defines appropriate biomechanical environment to which the embryonic heart is exposed. Quantitative assessment of the dynamic parameters of wall tissues and blood flow is required to further our understanding of cardiac development. We report the use of an ultrafast 1310-nm dual-camera spectral domain optical coherence tomography (SDOCT) system to characterize/image, in parallel, the dynamic radial strain rate of the myocardial wall and the Doppler velocity of the underlying flowing blood within an in vivo beating chick embryo. The OCT system operates at 184-kHz line scan rate, providing the flexibility of imaging the fast blood flow and the slow tissue deformation within one scan. The ability to simultaneously characterize tissue motion and blood flow provides a useful approach to better understand cardiac dynamics during early developmental stages.

  11. Mapping breast cancer blood flow index, composition, and metabolism in a human subject using combined diffuse optical spectroscopic imaging and diffuse correlation spectroscopy

    Science.gov (United States)

    Yazdi, Hossein S.; O'Sullivan, Thomas D.; Leproux, Anais; Hill, Brian; Durkin, Amanda; Telep, Seraphim; Lam, Jesse; Yazdi, Siavash S.; Police, Alice M.; Carroll, Robert M.; Combs, Freddie J.; Strömberg, Tomas; Yodh, Arjun G.; Tromberg, Bruce J.

    2017-04-01

    Diffuse optical spectroscopic imaging (DOSI) and diffuse correlation spectroscopy (DCS) are model-based near-infrared (NIR) methods that measure tissue optical properties (broadband absorption, μa, and reduced scattering, μs‧) and blood flow (blood flow index, BFI), respectively. DOSI-derived μa values are used to determine composition by calculating the tissue concentration of oxy- and deoxyhemoglobin (HbO2, HbR), water, and lipid. We developed and evaluated a combined, coregistered DOSI/DCS handheld probe for mapping and imaging these parameters. We show that uncertainties of 0.3 mm-1 (37%) in μs‧ and 0.003 mm-1 (33%) in μa lead to ˜53% and 9% errors in BFI, respectively. DOSI/DCS imaging of a solid tissue-simulating flow phantom and a breast cancer patient reveals well-defined spatial distributions of BFI and composition that clearly delineates both the flow channel and the tumor. BFI reconstructed with DOSI-corrected μa and μs‧ values had a tumor/normal contrast of 2.7, 50% higher than the contrast using commonly assumed fixed optical properties. In conclusion, spatially coregistered imaging of DOSI and DCS enhances intrinsic tumor contrast and information content. This is particularly important for imaging diseased tissues where there are significant spatial variations in μa and μs‧ as well as potential uncoupling between flow and metabolism.

  12. Highly spatially resolved velocity measurements of a turbulent channel flow by a fiber-optic heterodyne laser-Doppler velocity-profile sensor

    Energy Technology Data Exchange (ETDEWEB)

    Shirai, K.; Pfister, T.; Buettner, L.; Czarske, J. [Dresden University of Technology (TU Dresden), Department of Electrical Engineering and Information Technology, Chair for Measurement and Testing Techniques, Dresden (Germany); Mueller, H. [Physikalisch-Technische Bundesanstalt Braunschweig (PTB), Department 1.4 Gas Flow, Braunschweig (Germany); Becker, S.; Lienhart, H.; Durst, F. [Institute of Fluid Mechanics (LSTM), Friedrich-Alexander-University Erlangen-Nuernberg, Erlangen (Germany)

    2006-03-15

    Velocity measurements with a high spatial resolution are important in turbulent flow research. In this paper, we report on the development of a new fiber-optic laser-Doppler velocity-profile sensor exhibiting a spatial resolution of up to 5 {mu}m and its application to turbulent boundary layers. The sensor developed in the present work employs a frequency-division-multiplexing technique in order to separate two measurement signals from the two fringe systems. Velocity measurements close to zero at the solid wall were realized using heterodyne technique. The use of fiber optics improved a robustness of the sensor. The measurement accuracy of the sensor was experimentally investigated with respect to the spatial resolution and velocity. Universal velocity profile of a turbulent flow was obtained in a fully developed channel flow. Mean and fluctuating velocity are presented with a high spatial resolution. (orig.)

  13. Double-layer optical fiber coating analysis in MHD flow of an elastico-viscous fluid using wet-on-wet coating process

    Science.gov (United States)

    Khan, Zeeshan; Islam, Saeed; Shah, Rehan Ali; Khan, Muhammad Altaf; Bonyah, Ebenezer; Jan, Bilal; Khan, Aurangzeb

    Modern optical fibers require a double-layer coating on the glass fiber in order to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low and high density polyethylene (LDPE/HDPE), nylon and Polysulfone. One of the most important things which affect the final product after processing is the design of the coating die. In the present study, double-layer optical fiber coating is performed using melt polymer satisfying Oldroyd 8-constant fluid model in a pressure type die with the effect of magneto-hydrodynamic (MHD). Wet-on-wet coating process is applied for double-layer optical fiber coating. The coating process in the coating die is modeled as a simple two-layer Couette flow of two immiscible fluids in an annulus with an assigned pressure gradient. Based on the assumptions of fully developed laminar and MHD flow, the Oldroyd 8-constant model of non-Newtonian fluid of two immiscible resin layers is modeled. The governing nonlinear equations are solved analytically by the new technique of Optimal Homotopy Asymptotic Method (OHAM). The convergence of the series solution is established. The results are also verified by the Adomian Decomposition Method (ADM). The effect of important parameters such as magnetic parameter Mi , the dilatant constant α , the Pseodoplastic constant β , the radii ratio δ , the pressure gradient Ω , the speed of fiber optics V , and the viscosity ratio κ on the velocity profiles, thickness of coated fiber optics, volume flow rate, and shear stress on the fiber optics are investigated. At the end the result of the present work is also compared with the experimental results already available in the literature by taking non-Newtonian parameters tends to zero.

  14. Olive Oil Tracer Particle Size Analysis for Optical Flow Investigations in a Gas Medium

    Science.gov (United States)

    Harris, Shaun; Smith, Barton

    2014-11-01

    Seed tracer particles must be large enough to scatter sufficient light while being sufficiently small to follow the flow. These requirements motivate a desire for control over the particle size. For gas measurements, it is common to use atomized oil droplets as tracer particles. A Laskin nozzle is a device for generating oil droplets in air by directing high-pressure air through small holes under an oil surface. The droplet diameter frequency distribution can be varied by altering the hole diameter, the number of holes, or the inlet pressure. We will present a systematic study of the effect of these three parameters on the resultant particle distribution as it leaves the Laskin nozzle. The study was repeated for cases where the particles moved through a typical jet facility before their size was measured. While the jet facility resulted in an elimination of larger particles, the average particle diameter could be varied by a factor of two at both the seeder exit and downstream of the jet facility.

  15. RSI: oxygen consumption, blood flow, and reoxygenation in patients suffering RSI measured by noninvasive optical spectroscopy

    Science.gov (United States)

    Thijssen, Dick H. J.; van Uden, Caro J. T.; Krijgsman, Hans; Colier, Willy N. J. M.

    2003-07-01

    Background: Repetitive Strain Injury (RSI) is a major problem in nowadays health care and creates high financial costs and personal distress. Average prevalence rates in the Netherlands vary from 20-40% of the working population. Insight into the patho-physiological mechanism of RSI is important in order to establish adequate treatment and prevention programs. Objective: The aim of this study was to gain insight in muscle oxygen consumption (mVO2), blood flow (BF), and reoxygenation (ReOx) in the forearm of computer workers with stage III Repetitive Strain Injury (RSI). Method: We have used continuous wave infrared spectroscopy (NIRS) to measure these variables. Measurements were conducted on the extensor and flexor muscle in both arms as well in RSI-patients (n=10) as in control subjects (n=21). A protocol of increased isometric repetitive contraction in a handgrip ergonometer was used with increasing levels of strength. Results: mVO2 in the extensor muscle in RSI-subjects (dominant side) was increased compared to control subjects and compared to the non-dominant side (pmuscle). However, there was a tendency towards statistical significance (p=0.065). BF in rest was equal in both groups, however after exercise it tended to be increased. Half-time recovery (T ») was measured during only one part of the protocol and it was significantly increased (p<0.05). Conclusion: mVO2 in RSI is impaired. BF and ReOx did not show difference between both groups. Future research should aim at a microvascular dysfunction in RSI.

  16. An Optical Flow Method Applied to Co-Registration of Remote Sensing Images: Example for SAR/SAR, SAR/LIDAR, SAR/Optical Images of BIOSAR 2010 Campaign

    Science.gov (United States)

    Colin-Koeniguer, Elise

    2016-08-01

    This article proposes an optical flow type method for coregistration of forest remote sensing images. The principle of the algorithm called GeFolki is first explained. Results are shown on the images of the BioSAR 3 campaign, for the production of SAR interferograms, the coregistration a SAR and LIDAR image, and the coregistration an optical image and SAR image.The advantages of such an algorithm over conventional algorithms are explained. Finally, we propose various applications within the operating data for future BIOMASS mission: massive interferometry, ground truth production, upscaling by fusion of LIDAR and SAR data, and image mining.

  17. Connectivity Reveals Sources of Predictive Coding Signals in Early Visual Cortex During Processing of Visual Optic Flow.

    Science.gov (United States)

    Schindler, Andreas; Bartels, Andreas

    2016-05-24

    Superimposed on the visual feed-forward pathway, feedback connections convey higher level information to cortical areas lower in the hierarchy. A prominent framework for these connections is the theory of predictive coding where high-level areas send stimulus interpretations to lower level areas that compare them with sensory input. Along these lines, a growing body of neuroimaging studies shows that predictable stimuli lead to reduced blood oxygen level-dependent (BOLD) responses compared with matched nonpredictable counterparts, especially in early visual cortex (EVC) including areas V1-V3. The sources of these modulatory feedback signals are largely unknown. Here, we re-examined the robust finding of relative BOLD suppression in EVC evident during processing of coherent compared with random motion. Using functional connectivity analysis, we show an optic flow-dependent increase of functional connectivity between BOLD suppressed EVC and a network of visual motion areas including MST, V3A, V6, the cingulate sulcus visual area (CSv), and precuneus (Pc). Connectivity decreased between EVC and 2 areas known to encode heading direction: entorhinal cortex (EC) and retrosplenial cortex (RSC). Our results provide first evidence that BOLD suppression in EVC for predictable stimuli is indeed mediated by specific high-level areas, in accord with the theory of predictive coding.

  18. Flying over uneven moving terrain based on optic-flow cues without any need for reference frames or accelerometers.

    Science.gov (United States)

    Expert, Fabien; Ruffier, Franck

    2015-02-26

    Two bio-inspired guidance principles involving no reference frame are presented here and were implemented in a rotorcraft, which was equipped with panoramic optic flow (OF) sensors but (as in flying insects) no accelerometer. To test these two guidance principles, we built a tethered tandem rotorcraft called BeeRotor (80 grams), which was tested flying along a high-roofed tunnel. The aerial robot adjusts its pitch and hence its speed, hugs the ground and lands safely without any need for an inertial reference frame. The rotorcraft's altitude and forward speed are adjusted via two OF regulators piloting the lift and the pitch angle on the basis of the common-mode and differential rotor speeds, respectively. The robot equipped with two wide-field OF sensors was tested in order to assess the performances of the following two systems of guidance involving no inertial reference frame: (i) a system with a fixed eye orientation based on the curved artificial compound eye (CurvACE) sensor, and (ii) an active system of reorientation based on a quasi-panoramic eye which constantly realigns its gaze, keeping it parallel to the nearest surface followed. Safe automatic terrain following and landing were obtained with CurvACE under dim light to daylight conditions and the active eye-reorientation system over rugged, changing terrain, without any need for an inertial reference frame.

  19. Retrobulbar blood flow and visual organ function disturbance in the course of giant cell arteritis coexisting with optic disc drusen – a case repor

    Directory of Open Access Journals (Sweden)

    Monika Modrzejewska

    2013-09-01

    Full Text Available The review presented ophthalmologic syndrome connected with visual organ function disorder in giant cell arteritis patient concomitant with optic nerve disc drusen. Diagnostic difficulties were shown in relation to incidence of both similar ophthalmic symptoms as well as interpretation of specialists examinations results (pattern visual evoked potential test, scanning laser polarimetry, and perimetric tests – kinetic and static. Apart from ophthalmic investigations, significant role of radiological examinations was considered, especially color Doppler ultrasonography of retrobulbar circulation – optic artery, central retinal artery, long posterior ciliary arteries. Adequate interpretation of results seems to be crucial to establish scheme and timing of treatment in case of co-occurrence of the abovementioned disorders. In the presented case early implementation of steroid therapy resulted in improvement of blood flow parameters and the regression of ophthalmological complaints. Visual field deficiency in kinetic perimetry, reduced wave amplitude p100 in visual evoked potential test as well as decrease in number of optic nerve fibers in optic nerve disc region in scanning laser polarimetry exam can be diagnostic features in diagnosis of visual impairment in the course of giant cell arteritis and optic nerve disc drusen. Evaluation of blood flow velocity parameters in retrobulbar arteries in color Doppler ultrasonography is the most valuable screening in monitoring ophthalmic dysregulation in presented disorders.

  20. Perception of scene-relative object movement: Optic flow parsing and the contribution of monocular depth cues

    National Research Council Canada - National Science Library

    Warren, Paul A; Rushton, Simon K

    2009-01-01

    ...). Here, we explore whether stereo disparity is necessary for flow parsing or whether other sources of depth information, which could theoretically constrain flow-field interpretation, are sufficient...

  1. Geometry-driven folding transitions in floating thin films

    Science.gov (United States)

    Paulsen, Joseph D.; Démery, Vincent; Toga, K. Bugra; Qiu, Zhanlong; Davidovitch, Benny; Russell, Thomas P.; Menon, Narayanan

    When a thin elastic sheet is compressed, it forms wrinkles to gather excess material, while deforming the fluid or solid substrate by only a small amount. Upon further compression, the sheet may fold, in order to lower the mechanical energy of the system1. Here we demonstrate a folding transition that is independent of the mechanical properties of the sheet. We study the deformations of a thin polymer film that has an annular shape, floating on a planar air-water interface. By controlling the concentration of a surfactant outside the film, we vary the tension pulling on the outer boundary of the annulus. The sheet spontaneously folds at a threshold ratio of inner to outer surface tension that depends on the geometry of the sheet, but is independent of its bending rigidity. Our results are consistent with a simple geometric principle: the sheet adopts the unstretched shape that minimizes the interfacial energy of the exposed liquid2. Finally, we consider the application of this geometric principle to the folding of a floating indented film.1. Pocivavsek et al., Science 320, 912 (2008).2. Paulsen et al., Nature Materials, doi:10.1038/nmat4397 (2015).

  2. Geometry-Driven Folding of a Floating Annular Sheet.

    Science.gov (United States)

    Paulsen, Joseph D; Démery, Vincent; Toga, K Buğra; Qiu, Zhanlong; Russell, Thomas P; Davidovitch, Benny; Menon, Narayanan

    2017-01-27

    Predicting the large-amplitude deformations of thin elastic sheets is difficult due to the complications of self contact, geometric nonlinearities, and a multitude of low-lying energy states. We study a simple two-dimensional setting where an annular polymer sheet floating on an air-water interface is subjected to different tensions on the inner and outer rims. The sheet folds and wrinkles into many distinct morphologies that break axisymmetry. These states can be understood within a recent geometric approach for determining the gross shape of extremely bendable yet inextensible sheets by extremizing an appropriate area functional. Our analysis explains the remarkable feature that the observed buckling transitions between wrinkled and folded shapes are insensitive to the bending rigidity of the sheet.

  3. Using optical fibers with different modes to improve the signal-to-noise ratio of diffuse correlation spectroscopy flow-oximeter measurements

    Science.gov (United States)

    He, Lian; Lin, Yu; Shang, Yu; Shelton, Brent J.; Yu, Guoqiang

    2013-03-01

    The dual-wavelength diffuse correlation spectroscopy (DCS) flow-oximeter is an emerging technique enabling simultaneous measurements of blood flow and blood oxygenation changes in deep tissues. High signal-to-noise ratio (SNR) is crucial when applying DCS technologies in the study of human tissues where the detected signals are usually very weak. In this study, single-mode, few-mode, and multimode fibers are compared to explore the possibility of improving the SNR of DCS flow-oximeter measurements. Experiments on liquid phantom solutions and in vivo muscle tissues show only slight improvements in flow measurements when using the few-mode fiber compared with using the single-mode fiber. However, light intensities detected by the few-mode and multimode fibers are increased, leading to significant SNR improvements in detections of phantom optical property and tissue blood oxygenation. The outcomes from this study provide useful guidance for the selection of optical fibers to improve DCS flow-oximeter measurements.

  4. Investigation on Dynamic Calibration for an Optical-Fiber Solids Concentration Probe in Gas-Solid Two-Phase Flows

    OpenAIRE

    Changsui Zhao; Liu Shen; Pan Xu; Xiaoping Chen; Daoyin Liu; Cai Liang; Guiling Xu

    2013-01-01

    This paper presents a review and analysis of the research that has been carried out on dynamic calibration for optical-fiber solids concentration probes. An introduction to the optical-fiber solids concentration probe was given. Different calibration methods of optical-fiber solids concentration probes reported in the literature were reviewed. In addition, a reflection-type optical-fiber solids concentration probe was uniquely calibrated at nearly full range of the solids concentration from 0...

  5. Changes in strain and blood flow in the outflow tract of chicken embryo hearts observed with spectral domain optical coherence tomography after outflow tract banding

    Science.gov (United States)

    Ma, Zhenhe; Du, Linlin; Wang, Qiaoyun; Chu, Zhongdi; Zang, Xuan; Wang, Fengwen; Wang, Ruikang K.

    2013-02-01

    In this paper, we demonstrated the use of a spectral domain optical coherence tomography (OCT) in visualizing and quantifying changes in cardiac wall strain and blood-flow velocities under normal and altered hemodynamic conditions in chicken embryos at an early stage of development, focusing on the heart outflow tract (OFT). OCT imaging allowed in vivo evaluation strain and strain rate of the myocardium of the OFT through analyzing the periodic variation of the myocardial wall thickness. We found that alterations in hemodynamic conditions, through OFT banding, Changed strain and blood-flow velocities through the OFT as expected.

  6. Phase-resolved functional optical coherence tomography: simultaneous imaging of in situ tissue structure, blood flow velocity, standard deviation, birefringence, and Stokes vectors in human skin

    Science.gov (United States)

    Ren, Hongwu; Ding, Zhihua; Zhao, Yonghua; Miao, Jianjun; Nelson, J. Stuart; Chen, Zhongping

    2002-10-01

    We describe a phase-resolved functional optical coherence tomography system that can simultaneously yield in situ images of tissue structure, blood flow velocity, standard deviation, birefringence, and the Stokes vectors in human skin. Multifunctional images were obtained by processing of analytical interference fringe signals derived from two perpendicular polarization-detection channels. The blood flow velocity and standard deviation images were obtained by comparison of the phases from pairs of analytical signals in neighboring A-lines in the same polarization state. The analytical signals from two polarization-diversity detection channels were used to determine the four Stokes vectors for four reference polarization states. From the four Stokes vectors, the birefringence image, which is not sensitive to the orientation of the optical axis in the sample, was obtained. Multifunctional in situ images of a port wine stain birthmark in human skin are presented.

  7. Impact of intraocular pressure on changes of blood flow in the retina, choroid, and optic nerve head in rats investigated by optical microangiography

    OpenAIRE

    Zhi, Zhongwei; Cepurna, William O.; Johnson, Elaine C.; Morrison, John C.; Wang, Ruikang K.

    2012-01-01

    In this paper, we demonstrate the use of optical coherence tomography/optical microangiography (OCT/OMAG) to image and measure the effects of acute intraocular pressure (IOP) elevation on retinal, choroidal and optic nerve head (ONH) perfusion in the rat eye. In the experiments, IOP was elevated from 10 to 100 mmHg in 10 mmHg increments. At each IOP level, three-dimensional data volumes were captured using an ultrahigh sensitive (UHS) OMAG scanning protocol for 3D volumetric perfusion imaging...

  8. Aerosol generation of As and Se hydrides using a new Flow Blurring® multiple nebulizer for sample introduction in inductively coupled plasma optical emission spectrometry

    OpenAIRE

    Pereira, Catarinie D.; Aguirre Pastor, Miguel Ángel; NÓBREGA, Joaquim A.; Hidalgo Núñez, Montserrat; Canals Hernández, Antonio

    2014-01-01

    A new Flow Blurring® multiple nebulizer (FBMN) has been used for the efficient generation of As and Se hydrides directly into the aerosol formed inside the spray chamber before detection by inductively coupled plasma optical emission spectrometry (ICP OES). The FBMN allowed the hydride generation directly into the spray chamber without using any additional device either for solution and gas control or for gas phase separation. Synthetic solutions containing As and Se plus Ca, Mg and K were us...

  9. Fast simulated annealing and adaptive Monte Carlo sampling based parameter optimization for dense optical-flow deformable image registration of 4DCT lung anatomy

    Science.gov (United States)

    Dou, Tai H.; Min, Yugang; Neylon, John; Thomas, David; Kupelian, Patrick; Santhanam, Anand P.

    2016-03-01

    Deformable image registration (DIR) is an important step in radiotherapy treatment planning. An optimal input registration parameter set is critical to achieve the best registration performance with the specific algorithm. Methods In this paper, we investigated a parameter optimization strategy for Optical-flow based DIR of the 4DCT lung anatomy. A novel fast simulated annealing with adaptive Monte Carlo sampling algorithm (FSA-AMC) was investigated for solving the complex non-convex parameter optimization problem. The metric for registration error for a given parameter set was computed using landmark-based mean target registration error (mTRE) between a given volumetric image pair. To reduce the computational time in the parameter optimization process, a GPU based 3D dense optical-flow algorithm was employed for registering the lung volumes. Numerical analyses on the parameter optimization for the DIR were performed using 4DCT datasets generated with breathing motion models and open-source 4DCT datasets. Results showed that the proposed method efficiently estimated the optimum parameters for optical-flow and closely matched the best registration parameters obtained using an exhaustive parameter search method.

  10. Effects of Additional Oxygen Flow on the Optical and Electrical Properties of Ion Beam Sputtering Deposited Molybdenum-Doped Zinc Oxide Layer

    Directory of Open Access Journals (Sweden)

    Chin-Chiuan Kuo

    2012-01-01

    Full Text Available The transparent conductive molybdenum-doped zinc oxide (MZO was deposited onto a flexible polyethersulfone (PES substrate by using an ion beam sputtering system. An argon ion beam was used to sputter an MZO target at constant pressure of 0.67 Pa and substrate temperature of 130∘C with varying the oxygen flow rate from 0 to 12 sccm. The influences of additional oxygen flow on the microstructure, optical, and electrical properties of films were investigated. The obtained MZO films present a crystalline structure. With increasing the oxygen flow rate, their electrical resistivity increases, and the optical band gap decreases from 3.46 to 3.20 eV. The film deposited in the atmosphere without introducing oxygen exhibits the best optical transmittance of 82.9% at 550 nm wavelength, electrical resistivity of 8.32 × 10−3 Ω cm, carrier concentration of 6.82 × 1020 cm−3, and carrier mobility of 2.45 cm2/Vs.

  11. 基于光流能量的人体异常行为检测研究%Research on Human Abnormal Behavior Detection Based on Optical Flow Energy

    Institute of Scientific and Technical Information of China (English)

    罗超宇; 李小曼; 李浩

    2014-01-01

    研究并比较了当前常用的3种异常行为检测算法,分析了的各算法的研究现状,介绍了当前光流能量用于异常行为检测技术中的研究进展,提出一种基于区域光流能量的人体异常行为检测算法。采用Lucas-Kanade算法计算区域光流特征,实现对视频中打斗等剧烈异常行为的检测。仿真实验表明,算法具有较高的识别率和较低的误检率,具有一定研究意义。%This paper studies and compares three commonly-used kinds of abnormal behavior detection algorithms, analyzes their research status, introduces the research progress of optical flow energy used in abnormal behavior detection technology, proposes a human abnormal behavior detection algorithm based on regional optical flow energy. The Lucas-Kanade algorithm is used to calculate the regional optical flow characteristics and realize the severe abnormal behavior detection in the video such as fighting. The simulation test shows that the algorithm has such features as higher recognition rate and lower false detecting rate and presents certain research significance.

  12. Modeling of the blood flow in the lower extremities for dynamic diffuse optical tomography of peripheral artery disease

    Science.gov (United States)

    Marone, A.; Hoi, J. W.; Khalil, M. A.; Kim, H. K.; Shrikhande, G.; Dayal, R.; Hielscher, A. H.

    2015-07-01

    Peripheral Arterial Disease (PAD) is caused by a reduction of the internal diameters of the arteries in the upper or lower extremities mainly due to atherosclerosis. If not treated, its worsening may led to a complete occlusion, causing the death of the cells lacking proper blood supply, followed by gangrene that may require chirurgical amputation. We have recently performed a clinical study in which good sensitivities and specificities were achieved with dynamic diffuse optical tomography. To gain a better understanding of the physiological foundations of many of the observed effects, we started to develop a mathematical model for PAD. The model presented in this work is based on a multi-compartment Windkessel model, where the vasculature in the leg and foot is represented by resistors and capacitors, the blood pressure with a voltage drop, and the blood flow with a current. Unlike existing models, the dynamics induced by a thigh-pressure-cuff inflation and deflation during the measurements are taken into consideration. This is achieved by dynamically varying the resistances of the large veins and arteries. By including the effects of the thigh-pressure cuff, we were able to explain many of the effects observed during our dynamic DOT measurements, including the hemodynamics of oxy- and deoxy-hemoglobin concentration changes. The model was implemented in MATLAB and the simulations were normalized and compared with the blood perfusion obtained from healthy, PAD and diabetic patients. Our preliminary results show that in unhealthy patients the total system resistance is sensibly higher than in healthy patients.

  13. Minimalistic optic flow sensors applied to indoor and outdoor visual guidance and odometry on a car-like robot.

    Science.gov (United States)

    Mafrica, Stefano; Servel, Alain; Ruffier, Franck

    2016-11-10

    Here we present a novel bio-inspired optic flow (OF) sensor and its application to visual  guidance and odometry on a low-cost car-like robot called BioCarBot. The minimalistic OF sensor was robust to high-dynamic-range lighting conditions and to various visual patterns encountered thanks to its M(2)APIX auto-adaptive pixels and the new cross-correlation OF algorithm implemented. The low-cost car-like robot estimated its velocity and steering angle, and therefore its position and orientation, via an extended Kalman filter (EKF) using only two downward-facing OF sensors and the Ackerman steering model. Indoor and outdoor experiments were carried out in which the robot was driven in the closed-loop mode based on the velocity and steering angle estimates. The experimental results obtained show that our novel OF sensor can deliver high-frequency measurements ([Formula: see text]) in a wide OF range (1.5-[Formula: see text]) and in a 7-decade high-dynamic light level range. The OF resolution was constant and could be adjusted as required (up to [Formula: see text]), and the OF precision obtained was relatively high (standard deviation of [Formula: see text] with an average OF of [Formula: see text], under the most demanding lighting conditions). An EKF-based algorithm gave the robot's position and orientation with a relatively high accuracy (maximum errors outdoors at a very low light level: [Formula: see text] and [Formula: see text] over about [Formula: see text] and [Formula: see text]) despite the low-resolution control systems of the steering servo and the DC motor, as well as a simplified model identification and calibration. Finally, the minimalistic OF-based odometry results were compared to those obtained using measurements based on an inertial measurement unit (IMU) and a motor's speed sensor.

  14. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  15. Bending and turbulent enhancement phenomena of neutral gas flow containing an atmospheric pressure plasma by applying external electric fields measured by schlieren optical method

    Science.gov (United States)

    Yamada, Hiromasa; Yamagishi, Yusuke; Sakakita, Hajime; Tsunoda, Syuichiro; Kasahara, Jiro; Fujiwara, Masanori; Kato, Susumu; Itagaki, Hirotomo; Kim, Jaeho; Kiyama, Satoru; Fujiwara, Yutaka; Ikehara, Yuzuru; Ikehara, Sanae; Nakanishi, Hayao; Shimizu, Nobuyuki

    2016-01-01

    To understand the mechanism of turbulent enhancement phenomena of a neutral gas flow containing plasma ejected from the nozzle of plasma equipment, the schlieren optical method was performed to visualize the neutral gas behavior. It was confirmed that the turbulent starting point became closer to the nozzle exit, as the amplitude of discharge voltage (electric field) increased. To study the effect of electric field on turbulent enhancement, two sets of external electrodes were arranged in parallel, and the gas from the nozzle was allowed to flow between the upper and lower electrodes. It was found that the neutral gas flow was bent, and the bending angle increased as the amplitude of the external electric field increased. The results obtained using a simple model analysis roughly coincide with experimental data. These results indicate that momentum transport from drifted ions induced by the electric field to neutral particles is an important factor that enhances turbulence.

  16. Label-free in vivo optical micro-angiography imaging of cerebral capillary blood flow within meninges and cortex in mice with the skull left intact

    Science.gov (United States)

    Jia, Yali; Wang, Ruikang K.

    2011-03-01

    Abnormal microcirculation within meninges is common in many neurological diseases. There is a need for an imaging method that is capable of visualizing functional meningeal microcirculations alone, preferably decoupled from the cortical blood flow. Optical microangiography (OMAG) is a recently developed label-free imaging method capable of producing 3D images of dynamic blood perfusion within micro-circulatory tissue beds at an imaging depth up to ~2 mm, with an unprecedented imaging sensitivity to the blood flow at ~4 μm/s. In this study, we demonstrate the utility of ultra-high sensitive OMAG in imaging the detailed blood flow distributions, at a capillary level resolution, within meninges and cortex in mice with the cranium left intact. The results indicate that OMAG can be a valuable tool for the study of meningeal circulations.

  17. A bio-inspired, computational model suggests velocity gradients of optic flow locally encode ordinal depth at surface borders and globally they encode self-motion.

    Science.gov (United States)

    Raudies, Florian; Ringbauer, Stefan; Neumann, Heiko

    2013-09-01

    Visual navigation requires the estimation of self-motion as well as the segmentation of objects from the background. We suggest a definition of local velocity gradients to compute types of self-motion, segment objects, and compute local properties of optical flow fields, such as divergence, curl, and shear. Such velocity gradients are computed as velocity differences measured locally tangent and normal to the direction of flow. Then these differences are rotated according to the local direction of flow to achieve independence of that direction. We propose a bio-inspired model for the computation of these velocity gradients for video sequences. Simulation results show that local gradients encode ordinal surface depth, assuming self-motion in a rigid scene or object motions in a nonrigid scene. For translational self-motion velocity, gradients can be used to distinguish between static and moving objects. The information about ordinal surface depth and self-motion can help steering control for visual navigation.

  18. Effects of light intensity and pattern contrast on the ability of the land crab, Cardisoma guanhumi, to separate optic flow-field components.

    Science.gov (United States)

    Johnson, Aaron P; Barnes, W Jon P; Macauley, Martin W S

    2004-01-01

    Using a novel suite of computer-generated visual stimuli that mimicked components of optic flow, the visual responses of the tropical land crab, Cardisoma guanhumi, were investigated. We show that crabs are normally successful in distinguishing the rotational and translational components of the optic flow field, showing strong optokinetic responses to the former but not the latter. This ability was not dependent on the orientation of the crab, occurring both in "forwards-walking" and "sideways-walking" configurations. However, under conditions of low overall light intensity and/or low object/background contrast, the separation mechanism shows partial failure causing the crab to generate compensatory eye movements to translation, particularly in response to low-frequency (low-velocity) stimuli. Using this discovery, we then tested the ability of crabs to separate rotational and translational components in a combined rotation/translation flow field under different conditions. We demonstrate that, while crabs can successfully separate such a combined flow field under normal circumstances, showing compensatory eye movements only to the rotational component, they are unable to make this separation under conditions of low overall light intensity and low object/background contrast. Here, the responses to both flow-field components show summation when they are in phase, but, surprisingly, there is little reduction in the amplitude of responses to rotation when the translational component is in antiphase. Our results demonstrate that the crab's visual system finds separation of flow-field components a harder task than detection of movement, since the former shows partial failure at light intensities and/or object/background contrasts at which movement of the world around the crab is still generating high-gain optokinetic responses.

  19. Quantification and visualization of injury and regeneration to the ciliated epithelium using quantitative flow imaging and speckle variance optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Gamm, Ute A.; Huang, Brendan K.; Mis, Emily K.; Khokha, Mustafa K.; Choma, Michael A.

    2017-04-01

    Mucociliary flow is an important defense mechanism in the lung to remove inhaled pathogens and pollutants. A disruption of ciliary flow can lead to respiratory infections. Even though patients in the intensive care unit (ICU) either have or are very susceptible to respiratory infections, mucociliary flow is not well understood in the ICU setting. We recently demonstrated that hyperoxia, a consequence of administering supplemental oxygen to a patient in respiratory failure, can lead to a significant reduction of cilia-driven fluid flow in mouse trachea. There are other factors that are relevant to ICU medicine that can damage the ciliated tracheal epithelium, including inhalation injury and endotracheal tube placement. In this study we use two animal models, Xenopus embryo and ex vivo mouse trachea, to analyze flow defects in the injured ciliated epithelium. Injury is generated either mechanically with a scalpel or chemically by calcium chloride (CaCl2) shock, which efficiently but reversibly deciliates the embryo skin. In this study we used optical coherence tomography (OCT) and particle tracking velocimetry (PTV) to quantify cilia driven fluid flow over the surface of the Xenopus embryo. We additionally visualized damage to the ciliated epithelium by capturing 3D speckle variance images that highlight beating cilia. Mechanical injury disrupted cilia-driven fluid flow over the injured site, which led to a reduction in cilia-driven fluid flow over the whole surface of the embryo (n=7). The calcium chloride shock protocol proved to be highly effective in deciliating embryos (n=6). 3D speckle variance images visualized a loss of cilia and cilia-driven flow was halted immediately after application. We also applied CaCl2-shock to cultured ex vivo mouse trachea (n=8) and found, similarly to effects in Xenopus embryo, an extensive loss of cilia with resulting cessation of flow. We investigated the regeneration of the ciliated epithelium after an 8 day incubation period

  20. An Improved Optical Flow Method for Image Registration with Large-scale Movements%一种应用于图像配准中大尺度位移估计的改进光流法

    Institute of Scientific and Technical Information of China (English)

    熊静旖; 罗予频; 唐光荣

    2008-01-01

    In this paper, an improved optical flow method for image registration is proposed. It is novel in the way that it improves the optical flow method with an initial motion estimator: extended phase correlation technique (EPCT), using merits of the latter to compensate deficiencies of the former. In a more detailed manner, it can be said that the optical flow method can reach the sub-pixel accuracy and calculate complex distortion patterns like chirping and tilting but is weak with large-scale movements. Because EPCT covers measurements of large translations and rotations with pixel level accuracy and is efficient in the calculating load, it can be treated as a good initial motion estimator for optical flow method. Tests have proved that this improved method will significantly enhance the registration performance, especially, for images with large-scale movements and robust against random noises.

  1. Optical dynamic imaging of the regional blood flow in the rat mesentery under the effect of noradrenalin

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The regional blood flow in the rat mesentery under the effect of noradrenalin is monitored using the laser speckle imaging method. The results show that at the third minute of application of noradrenalin, the blood flow begins to decrease, and the venule blood flow decreases more rapidly than that in the arteriole. Five minutes later blood flow in part of blood vessels begins to resume and the blood flow in the arteriole recovers more quickly than that in the venule. These suggest that laser speckle imaging can obtain the temporal-spatial characteristic of blood flow in mesentery without the need of scanning. It provides a new approach for investigating the change of regional blood flow in the mesentery in microcirculation studies.

  2. An investigation of fluid flow during induction stroke of a water analog model of an IC engine using an innovative optical velocimetry concept: LIPA

    Science.gov (United States)

    Stier, Bernd; Falco, R. E.

    1994-01-01

    Optical measurements on an axisymmetrical quartz component engine research model were made to evaluate the flow field encountered during induction. The measurement technique is LIPA (Laser Induced Photochemical Anemometry), a non-intrusive velocimetry concept that provides an investigator of fluid flow with a tool to attain planar information about three-dimensional velocity and vorticity vectors in a single measurement step. The goal of this investigation is to further develop this measurement technique and apply it to study the induction stroke of a water analog model of a four-stroke internal combustion engine. The research conducted in the water analog model is a fundamental scientific inquiry into the flow fields that develop in the induction stroke of an engine at idling engine speeds. As this is the first investigation of its kind using LIPA technique, our goal has been to quantify, in a preliminary manner, the flow field features that develop during the intake stroke. In the process a more comprehensive understanding of the flow field features was developed, and tied to the quantification. The study evaluated the flow field of the intake stroke by estimating fields of velocity and vorticity. On the basis of these data, information about fluid dynamics during induction at engine speeds of 10, 20, and 30 RPM (corresponding to 170, 340, and 510 RPM respectively, when air is the flowing medium) for three different valve lifts was obtained. The overall development of the flow field, its energy content (kinetic, fluctuation) for the different settings of the engine parameters, vorticity information, and cyclic variations have been quantified. These have been discussed in terms of mixing performance.

  3. Optical monitoring of the concentration profile of submicron latex particles in flow through a translucent water-permeable tube: demonstration of flow-dependent concentration polarization of plasma proteins at a blood/endothelium boundary

    Science.gov (United States)

    Wada, Shigeo; Iwai, Toshiaki; Karino, Takeshi

    1999-05-01

    It is well accepted that hemodynamics plays an important role in atherogenesis in man. However, the precise mechanisms have not been elucidated yet. Recently, Karino and his coworkers hypothesized that flow-dependent concentration polarization of low-density lipoproteins (LDL: a carrier of cholesterol) may occur at a blood/endothelium boundary, leading to a high risk of atherogenesis in regions of slow flow and low wall shear rate where the concentration of LDL builds up. In this study, we attempted to confirm experimentally their predictions by measuring optically the concentration profile of polystyrene microspheres (used as a model of LDL) flowing in steady flow through a dialyses tube (used as a model of an artery) by transversing a laser beam across the tube and detecting the intensity of the transmitted light. It was found that surface concentration of the microsphere certainly increases with decreasing the flow rate (hence wall shear rate) and it occurs even under the conditions of a very low water filtration velocity encountered in normal arteries in vivo, thus giving a strong support to the hypothesis proposed by Karino et al.

  4. Quantification and visualization of injury and regeneration in the developing ciliated epithelium using quantitative flow imaging and speckle variance optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Gamm, Ute A.; Huang, Brendan K.; Mis, Emily K.; Khokha, Mustafa K.; Choma, Michael A.

    2017-02-01

    Premature infants are at a high risk for respiratory diseases owing to an underdeveloped respiratory system that is very susceptible to infection and inflammation. One aspect of respiratory health is the state of the ciliated respiratory epithelium which lines the trachea and bronchi. The ciliated epithelium is responsible for trapping and removing pathogens and pollutants from the lungs and an impairment of ciliary functionality can lead to recurring respiratory infections and subsequent lung damage. Mechanisms of cilia-driven fluid flow itself but also factors influenced by development like ciliary density and flow generation are incompletely understood. Furthermore, medical interventions like intubation and accidental aspiration can lead to focal or diffuse loss of cilia and disruption of flow. In this study we use two animal models, Xenopus embryo and ex vivo mouse trachea, to analyze flow defects in the injured ciliated epithelium. Injury is generated either mechanically with a scalpel or chemically by calcium chloride (CaCl2) shock, which efficiently but reversibly deciliates the embryo skin. In this study we used optical coherence tomography (OCT) and particle tracking velocimetry (PTV) to quantify cilia driven fluid flow over the surface of the Xenopus embryo. We additionally visualized damage to the ciliated epithelium by capturing 3D speckle variance images that highlight beating cilia. Mechanical injury disrupted cilia-driven fluid flow over the injured site, which led to a reduction in cilia-driven fluid flow over the whole surface of the embryo (n=7). The calcium chloride shock protocol proved to be highly effective in deciliating embryos (n=6). 3D speckle variance images visualized a loss of cilia and cilia-driven flow was halted immediately after application. We also applied CaCl2-shock to cultured ex vivo mouse trachea (n=8) and found, similarly to effects in Xenopus embryo, an extensive loss of cilia with resulting cessation of flow. We

  5. Optical-flow based circle biased proportional navigation%基于光流信息的圆弧偏置比例导引规律

    Institute of Scientific and Technical Information of China (English)

    覃天; 陈万春; 邢晓岚

    2011-01-01

    For the passive homing missiles, a developed guidance law based on optical flow was proposed to impact a moving target with an impact angle constraint. In contrast to optical-flow based circle navigation guidance, it is more practical and precise. Meanwhile the improved one does not require the range information, which avoids the problem that the range information can not be measured directly by a passive homing seeker. Based on a measurement model using an optical sensor and optical flow calculation and inspired by the insect navigation, the optical flow was used in guidance and control for a passive homing missile. Employing the structure of biased proportional navigation, the bias term was redesigned to ensure the impact angle. The simulation results show that, a small miss distance and a desired impact angle are obtained when the new guidance law is used to impact a moving ground target, also this guidance law is much robust to measurement noise.%提出了一种改进的用于被动寻的导弹的基于光流带落角约束的导引规律,其具有更强的适应性和更小的落角误差,而且该导引律不要求弹目距离信息,克服了被动寻的导弹不能测距的约束.基于采用光学传感器和光流算法的测量模型,受昆虫导航的启发,利用光流信息进行被动寻的导弹的导引和控制.同时借鉴偏置比例导引律的结构,重新设计偏置项,实现导弹以期望的落角命中目标.仿真表明,拦截地面运动目标时,该导引律在保证小脱靶量的同时,基本达到期望的落角,对于测量噪声也具有较好的鲁棒性.

  6. Tuning the optical properties of RF-PECVD grown μc-Si:H thin films using different hydrogen flow rate

    Science.gov (United States)

    Dushaq, Ghada; Nayfeh, Ammar; Rasras, Mahmoud

    2017-07-01

    In this paper we study the effect of H2/SiH4 dilution ratio (R) on the structural and optical properties of hydrogenated microcrystalline silicon embedded in amorphous matrix thin films. The thin films are prepared using standard RF-PECVD process at substrate temperature of 200 °C. The effect of hydrogen dilution ratio on the optical index of refraction and the absorption coefficient were investigated. It was observed that by incorporating higher hydrogen flow rate in the films with low SiH4 concentration, the optical index of refraction can be tuned over a broad range of wavelengths due to the variation of crystalline properties of the produced films. By varying the hydrogen flow of μc-Si:H samples, ∼8% and 12% reduction in the index of refraction at 400 nm and at 1500 nm can be achieved, respectively. In addition a 78% reduction in surface roughness is obtained when 60sccm of H2 is used in the deposition compared to the sample without any H2 incorporation.

  7. Effect of various nitrogen flow ratios on the optical properties of (Hf:N-DLC films prepared by reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Meng Qi

    2017-08-01

    Full Text Available Hf and N co-doped diamond-like carbon [(Hf:N-DLC] films were deposited on 316L stainless steel and glass substrates through reactive magnetron sputtering of hafnium and carbon targets at various nitrogen flow ratios (R=N2/[N2+CH4+Ar]. The effects of chemical composition and crystal structure on the optical properties of the (Hf:N-DLC films were studied. The obtained films consist of uniform HfN nanocrystallines embedded into the DLC matrix. The size of the graphite clusters with sp2 bonds (La and the ID/IG ratio increase to 2.47 nm and 3.37, respectively, with increasing R. The optical band gap of the films decreases from 2.01 eV to 1.84 eV with increasing R. This finding is consistent with the trends of structural transformations and could be related to the increase in the density of π-bonds due to nitrogen incorporation. This paper reports the influence of nitrogen flow ratio on the correlation among the chemical composition, crystal structure, and optical properties of (Hf:N-DLC films.

  8. An Efficient TV-L^1 Optical Flow Method%一种高精度的TV-L^1光流算法

    Institute of Scientific and Technical Information of China (English)

    涂志刚; 谢伟; 熊淑芬; 秦前清

    2012-01-01

    介绍了一种求解光流方程的新型数值方法。针对变分光流法无法有效检测由于间断、遮挡等造成的错误光流分量的缺陷,引入了光流有效性检测技术,同时提出了邻域修正法来修正错误分量。并采用结构纹理分解、加权中值滤波、金字塔等高效的光流技术,进一步增强了光流算法的精确性与实用性。%A new type of numerical method to solve variational optical flow equations is illus- trated. Introduce an efficient flow vector availability strategy to detect the wrong compo- nents which are caused by discontinuities, occlusions, etc, and then, a neighboring correc tion approach is proposed the correct them. Some advanced techniques are employed into the compute procedure, which further strengthen the accuracy and applicability of the variational optical flow algorithms.

  9. Infrared spectroscopic methods for the study of aerosol particles using White cell optics: Development and characterization of a new aerosol flow tube

    Science.gov (United States)

    Nájera, Juan J.; Fochesatto, Javier G.; Last, Deborah J.; Percival, Carl J.; Horn, Andrew B.

    2008-12-01

    A description of a new aerosol flow tube apparatus for measurements in situ under atmospherically relevant conditions is presented here. The system consists of a laboratory-made nebulizer generation system and a flow tube with a White cell-based Fourier transform IR for the detection system. An assessment of the White cell coupled to the flow tube was carried out by an extensive set of experiments to ensure the alignment of the infrared beam and optimize the performance of this system. The detection limit for CO was established as (1.0±0.3) ppm and 16 passes was chosen as the optimum number of passes to be used in flow tube experiments. Infrared spectroscopy was used to characterize dry aerosol particles in the flow tube. Pure particles composed of ammonium sulfate or sodium chloride ranging between 0.8 and 2.1 μm for size diameter and (0.8-4.9)×106 particles/cm3 for density number were generated by nebulization of aqueous solutions. Direct measurements of the aerosol particle size agree with size spectra retrieved from inversion of the extinction measurements using Mie calculations, where the difference residual value is in the order of 0.2%. The infrared detection limit for ammonium sulfate aerosol particles was determined as dp=0.9 μm and N =5×103 particles/cm3 with σ =1.1 by Mie calculation. Alternatively, Mie calculations were performed to determine the flexibility in varying the optical length when aerosol particles are sent by the injector. The very good agreement between the values retrieved for aerosol particles injected through the flow tube or through the injector clearly validates the estimation of the effective optical path length for the injector. To determine the flexibility in varying the reaction zone length, analysis of the extinction spectra as function of the position of the injector was carried out by monitoring the integrated area of different absorption modes of the ammonium sulfate. We conclude that the aerosol loss in the flow tube

  10. High-performance flat data center network architecture based on scalable and flow-controlled optical switching system

    Science.gov (United States)

    Calabretta, Nicola; Miao, Wang; Dorren, Harm

    2016-03-01

    Traffic in data centers networks (DCNs) is steadily growing to support various applications and virtualization technologies. Multi-tenancy enabling efficient resource utilization is considered as a key requirement for the next generation DCs resulting from the growing demands for services and applications. Virtualization mechanisms and technologies can leverage statistical multiplexing and fast switch reconfiguration to further extend the DC efficiency and agility. We present a novel high performance flat DCN employing bufferless and distributed fast (sub-microsecond) optical switches with wavelength, space, and time switching operation. The fast optical switches can enhance the performance of the DCNs by providing large-capacity switching capability and efficiently sharing the data plane resources by exploiting statistical multiplexing. Benefiting from the Software-Defined Networking (SDN) control of the optical switches, virtual DCNs can be flexibly created and reconfigured by the DCN provider. Numerical and experimental investigations of the DCN based on the fast optical switches show the successful setup of virtual network slices for intra-data center interconnections. Experimental results to assess the DCN performance in terms of latency and packet loss show less than 10^-5 packet loss and 640ns end-to-end latency with 0.4 load and 16- packet size buffer. Numerical investigation on the performance of the systems when the port number of the optical switch is scaled to 32x32 system indicate that more than 1000 ToRs each with Terabit/s interface can be interconnected providing a Petabit/s capacity. The roadmap to photonic integration of large port optical switches will be also presented.

  11. 基于光流空间分布的步态识别方法%Gait recognition method based on spatial distribution of optical flow

    Institute of Scientific and Technical Information of China (English)

    杨阳; 郭继昌

    2013-01-01

    Concerning the disadvantages of the traditional gait recognition method based on optical flow,such as complex system and low recognition rate.This paper proposed an improved model-free method—the spatial distribution of the optical flow to descript and recognize moving target.First,it computed dense optical flow for each image in a sequence and derive scale-independent scalar features which characterized the spatial distribution of the flow.Then,it analyzed periodic structure of these sequences of scalars.The scalar sequences for an image sequence has the same fundamental period but differ in phase.The phase feature vectors could be used to recognize individuals.Lastly,for each sample,trained the average of feature vectors as cluster centers.Sequences were classified to the nearest class based on the nearest neighbor rule.The experiment results show that,in the CASIA gait database,90% recognition rate or higher can be reached.%针对传统基于光流法步态识别复杂、识别率不高的缺点,提出了一种非模型化的方法——光流空间分布来描述并识别运动目标.首先,计算每帧步态序列中的密度光流场,所得的与尺度无关的矩描述了光流的空间形状分布;然后,分析每一组矩的周期性结构特征,不同图像序列对应的矢量有基本相同的周期特征和不同的相位特征,利用相位特征区分不同个体步态之间的差异;最后,训练时计算各个样本特征矢量的平均值作为聚类中心,识别时计算待识别序列矢量和每个聚类中心的距离,采用最近邻法则,把序列归类到距离最近的类中.实验证明,该算法在CASIA步态数据库上最高能达到90%以上的识别率.

  12. Statistical parametric mapping of stimuli-evoked changes in quantitative blood flow using extended-focus optical coherence microscopy (Conference Presentation)

    Science.gov (United States)

    Marchand, Paul J.; Bouwens, Arno; Shamaei, Vincent; Nguyen, David; Extermann, Jerome; Bolmont, Tristan; Lasser, Theo

    2016-03-01

    Magnetic Resonance Imaging has revolutionised our understanding of brain function through its ability to image human cerebral structures non-invasively over the entire brain. By exploiting the different magnetic properties of oxygenated and deoxygenated blood, functional MRI can indirectly map areas undergoing neural activation. Alongside the development of fMRI, powerful statistical tools have been developed in an effort to shed light on the neural pathways involved in processing of sensory and cognitive information. In spite of the major improvements made in fMRI technology, the obtained spatial resolution of hundreds of microns prevents MRI in resolving and monitoring processes occurring at the cellular level. In this regard, Optical Coherence Microscopy is an ideal instrumentation as it can image at high spatio-temporal resolution. Moreover, by measuring the mean and the width of the Doppler spectra of light scattered by moving particles, OCM allows extracting the axial and lateral velocity components of red blood cells. The ability to assess quantitatively total blood velocity, as opposed to classical axial velocity Doppler OCM, is of paramount importance in brain imaging as a large proportion of cortical vascular is oriented perpendicularly to the optical axis. We combine here quantitative blood flow imaging with extended-focus Optical Coherence Microscopy and Statistical Parametric Mapping tools to generate maps of stimuli-evoked cortical hemodynamics at the capillary level.

  13. A single laser all fibre based optical sensor and switching system and method for measuring velocity in atmospheric air flow

    DEFF Research Database (Denmark)

    2013-01-01

    A system for measuring a velocity of tracer particle motion in a fluid comprising at least one laser emitter configured to emit a continuous wave laser beam and a plur ality of optical devices being configured to alternately receive a laser beam, focusing the laser beam onto a same probe volume c...

  14. Measurement of the location of a particle in three dimensions using Mie scattering theory and wave optics: Application to flow in a microscopic field of view

    Science.gov (United States)

    Das, Kamal Kanti

    In this research, we have sought to develop a technique for measuring three-dimensional flow fields in small fluid volumes seeded with small spherical particles using a high numerical aperture (NA) microscope. The technique relies upon the knowledge of how the light is scattered from the particles to accurately determine their three dimensional position. We have combined Mie scattering theory and wave optics to predict the scattered field from spherical particles in a fluid medium using high NA collection optics. The model uses Mie scattering theory to calculate the optical field distribution on the intermediate planar interface between glass and air and then adopts a ray approach to propagate the field to the entrance pupil of an imaging system. We do not use a paraxial (parabolic wavefront) approximation and, therefore, our approach is applicable to the modeling of imaging systems with high aperture objectives. We have verified our theoretical model by measuring the scattering from polystyrene spheres illuminated with partially coherent, Koehler illumination in a transmitted light microscope with a 0.5 NA objective. Good agreement between our model and the experiment was achieved. We also developed a non-paraxial transformation for the lens and a vectorial model for the electromagnetic fields collected by a high NA objective. The model was also to determine the three-dimensional microscale based upon the motion of small particles in a seeded fluid. Application to laminar flow in a sub-millimeter channel and a thin liquid film demonstrate the utility of the technique. Preliminary results show that a wavelet based denoising technique may be used to process the data without loss of resolution.

  15. Optical diagnostics study of air flow and powder fluidisation in Nexthaler®--Part I: Studies with lactose placebo formulation.

    Science.gov (United States)

    Pasquali, I; Merusi, C; Brambilla, G; Long, E J; Hargrave, G K; Versteeg, H K

    2015-12-30

    Effective drug delivery to the lungs by a DPI device requires the air-stream through the device to have sufficient power to aerosolise the powder. Furthermore, sufficient turbulence must be induced, along with particle-wall and particle-particle collisions, in order to de-aggregate small drug particles from large carrier particles. As a result, the emitted and the fine particle doses produced by many commercially available DPI devices tend to be strongly affected by the natural inter-patient variability of the inhaled air flow. The Nexthaler® is a multi-dose breath-actuated dry-powder inhaler with minimum drug delivery-flow rate dependency and incorporating a dose protector. The actuation mechanism of the dose-protector ensures that the dose is only exposed to the inhaled air flow if the flow has sufficient power to cause complete aerosolisation. For this study, a proprietary lactose placebo powder blend was filled into "transparent" Nexthaler® to allow application of high-speed imaging and particle image velocimetry (PIV) techniques to successfully interrogate and reveal details of the powder entrainment and emission processes coupled with characterisation of the flow environment in the vicinity of the mouthpiece exit. The study showed that fluidisation of the bulk of the powder occurs very quickly (∼20ms) after withdrawal of the dose protector followed by powder emission from the device within ∼50ms thereafter. The bulk of the metered placebo dose was emitted within 100-200ms. The visualisation study also revealed that a very small fraction of powder fines is emitted whilst the dose protector still covers the dosing cup as the flow rate through the device accelerates. The PIV results show that the flow exiting the device is highly turbulent with a rotating flow structure, which forces the particles to follow internal paths having a high probability of wall impacts, suggesting that the flow environment inside the Nexthaler® DPI will be very beneficial for

  16. A noninvasive optical system for the measurement of xylem and phloem sap flow in woody plants of small stem size.

    Science.gov (United States)

    Helfter, Carole; Shephard, Jonathon D; Martinez-Vilalta, Jordi; Mencuccini, Maurizio; Hand, Duncan P

    2007-02-01

    Over the past 70 years, heat has been widely used as a tracer for estimating the flow of water in woody and herbaceous plants. However, most commercially available techniques for monitoring whole plant water use are invasive and the measurements are potentially flawed because of wounding of the xylem tissue. The study of photosynthate transport in the phloem remains in its infancy, and little information about phloem transport rates is available owing to the fragility of the vascular tissue. The aim of our study was to develop a compact, stand-alone non-invasive system allowing for direct detection of phloem and xylem sap movement. The proposed method uses a heat pulse as a tracer for sap flow. Heat is applied to the surface of the stem with a near-infrared laser source, and heat propagation is monitored externally by means of an infrared camera. Heat pulse velocities are determined from the thermometric data and related to the more useful quantity, mass flow rate. Simulation experiments on the xylem tissue of severed silver birch (Betula pendula Roth.) branch segments were performed to assess the feasibility of the proposed approach, highlight the characteristics of the technique and outline calibration strategies. Good agreement between imposed and measured flow rates was achieved leading to experimentation with live silver birch and oak (Quercus robur L.) saplings. It was demonstrated that water flow through xylem vessels can be monitored non-invasively on an intact stem with satisfactory accuracy despite simultaneous sugar transport in the phloem. In addition, it was demonstrated that the technique allows for unequivocal detection of phloem flow velocities.

  17. [A preliminary study on macular retinal and choroidal thickness and blood flow change after posterior scleral reinforcement by optical coherence tomography angiography].

    Science.gov (United States)

    Zhang, X F; Qiao, L Y; Li, X X; Ma, N; Li, M; Guan, Z; Wang, H Z; Wang, N L

    2017-01-11

    Objective: To investigate macular retinal and choroidal thickness and blood flow change using optical coherence tomography angiography after posterior scleral reinforcement (PSR) surgery. Methods: Prospective study. Twenty eyes of 10 patients with high myopia were enrolled in this open-label, single-treatment group and prospective study. Radial lines and Angio retina (3 mm×3 mm) module were performed for 20 eyes using Angio-vue optical coherence tomography (Avanti, Optovue) without pupil dilation, and best corrected visual acuity, spherical equivalent and axial length were compared before and 60 days after surgery. Retinal and choroidal thickness was measured in the fovea, 1 mm superior, 1 mm inferior, 1 mm nasal and 1 mm temporal to the fovea. Flow area, flow density and flow index were recorded using self-provided software in the superficial retina layer, deep retina layer, outer retina layer and choroid capillary layer, respectively. Statistical analysis was performed using SPSS 16.0. Data that followed normal distribution were compared with paired two-sample t-test, while others were compared with Wilcoxon signed rank test. Results: Of the patients participating in this preliminary study, the mean age was (35.5±4.2) years, and 50% were female. No significant difference was found between before and 60 days after PSR surgery in best corrected visual acuity (t=0.99, P=0.33), spherical equivalent (t=-1.89, P=0.07) and axial length (t=0.2, P=0.08). The retinal thickness in the fovea was thinner (Z=-2.58, P=0.01), while there was no significant difference in the 1 mm superior (t=0.44, P=0.67) , 1 mm inferior (t=0.05, P=0.96) , 1 mm nasal (Z=0.87, P=0.64) and 1 mm temporal (Z=-0.78, P=0.99) to the fovea. No significant difference was found in choroidal thickness (t=-0.12, P=0.87; t=-0.25, P=0.81. t=0.53, P=0.61; t=-0.91, P=0.38. t=1.2, P=0.25) before and after surgery. The postoperative flow density in the superficial and deep retinal layers (48.18±4.56% and 31.47

  18. Monitoring hypoxia induced changes in cochlear blood flow and hemoglobin concentration using a combined dual-wavelength laser speckle contrast imaging and Doppler optical microangiography system.

    Directory of Open Access Journals (Sweden)

    Roberto Reif

    Full Text Available A synchronized dual-wavelength laser speckle contrast imaging (DWLSCI system and a Doppler optical microangiography (DOMAG system was developed to determine several ischemic parameters in the cochlea due to a systemic hypoxic challenge. DWLSCI can obtain two-dimensional data, and was used to determine the relative changes in cochlear blood flow, and change in the concentrations of oxyhemoglobin (HbO, deoxyhemoglobin (Hb and total hemoglobin (HbT in mice. DOMAG can obtain three-dimensional data, and was used to determine the changes in cochlear blood flow with single vessel resolution. It was demonstrated that during a hypoxic challenge there was an increase in the concentrations of Hb, a decrease in the concentrations of HbO and cochlear blood flow, and a slight decrease in the concentration of HbT. Also, the rate of change in the concentrations of Hb and HbO was quantified during and after the hypoxic challenge. The ability to simultaneously measure these ischemic parameters with high spatio-temporal resolution will allow the detailed quantitative analysis of several hearing disorders, and will be useful for diagnosing and developing treatments.

  19. Laser-optical fiber Bragg grating anemometer for measuring gas flows: application to measuring the electric wind.

    Science.gov (United States)

    Lamb, David W; Hooper, Adam

    2006-04-15

    A novel laser-optical fiber Bragg grating anemometer (FBGA) has been devised for measuring the speed of a moving gas in the range 0-1.5 m s(-1). As a test, the FBGA was applied to measuring the speed of the electric wind generated in the particularly harsh, high-voltage environment of a dc, negative-polarity, partial (corona) discharge in atmospheric air. The instrument proved more stable and yielded an order-of-magnitude improvement in sensitivity (deltav approximately 4 x 10(-3) ms(-1)) compared with other optical-fiber-based anemometers. On-axis wind speeds ranging from zero to 1.1 m s(-1) were measured in the vicinity of the corona discharge.

  20. X-RAY AND OPTICAL EMISSION-LINE FILAMENTS IN THE COOLING FLOW CLUSTER 2A 0335+096

    NARCIS (Netherlands)

    SARAZIN, CL; OCONNELL, RW; MCNAMARA, BR

    1992-01-01

    We present a new high-resolution X-ray image of the 2A 0335 + 096 cluster of galaxies obtained with the High Resolution Imager (HRI) aboard the ROSAT satellite. The presence of dense gas having a very short cooling time in the central regions confirms its earlier identification as a cooling flow. Th

  1. Field-flow fractionation: An efficient approach for matrix removal of soil extract for inductively coupled plasma optical emission spectrometry

    Science.gov (United States)

    Sangsawong, Supharart; Waiyawat, Weerawan; Shiowatana, Juwadee; Siripinyanond, Atitaya

    2011-06-01

    An on-line coupling between a continuous-flow sequential extraction (CFSE) unit and flow field-flow fractionation with cross flow matrix removal (FlFFF/CFM) with ICP-OES detection was developed for determination of metal leachability from soil. The use of high concentration of Mg(NO 3) 2 in exchangeable phase can cause undesirable matrix effects by shifting ionization equilibrium in the plasma, etc., resulting in a clear need for matrix removal. Therefore, the capability of FlFFF/CFM to remove Mg matrix ion from soil extract was evaluated. Poly(ethylene imine) (PEI) having molecular weight of 25,000 Da was added to form complexes with analyte elements (Cu, Mn, Pb, and Zn) but not the matrix element (Mg). The free Mg matrix ions were then removed by filtering off through the ultrafiltration membrane, having a 1000-Da molecular weight cut-off, inside the FlFFF channel. With the use of FlFFF/CFM, matrix removal efficiency was approximately 83.5%, which was equivalent to approximately 6-fold dilution of the matrix ion. The proposed hyphenated system of CFSE and FlFFF/CFM with ICP-OES detection was examined for its reliability by checking with SRM 2710 (a highly contaminated soil from Montana). The metal contents determined by the proposed method were not significantly different (at 95% confidence) from the certified values.

  2. X-RAY AND OPTICAL EMISSION-LINE FILAMENTS IN THE COOLING FLOW CLUSTER 2A 0335+096

    NARCIS (Netherlands)

    SARAZIN, CL; OCONNELL, RW; MCNAMARA, BR

    1992-01-01

    We present a new high-resolution X-ray image of the 2A 0335 + 096 cluster of galaxies obtained with the High Resolution Imager (HRI) aboard the ROSAT satellite. The presence of dense gas having a very short cooling time in the central regions confirms its earlier identification as a cooling flow. Th

  3. Particle streak velocimetry-optical coherence tomography: a novel method for multidimensional imaging of microscale fluid flows.

    Science.gov (United States)

    Zhou, Kevin C; Huang, Brendan K; Gamm, Ute A; Bhandari, Vineet; Khokha, Mustafa K; Choma, Michael A

    2016-04-01

    We present a new OCT method for flow speed quantification and directional velocimetry: particle streak velocimetry-OCT (PSV-OCT). PSV-OCT generates two-dimensional, 2.5-vector component (vx ,|vy |,vz ) maps of microscale flow velocity fields. Knowledge of 2.5-vector components also enables the estimation of total flow speed. The enabling insight behind PSV-OCT is that tracer particles in sparsely-seeded fluid flow trace out streaks in (x,z,t)-space. The streak orientations in x-t and z-t yield vx and vz , respectively. The in-plane (x-z plane) residence time yields the out-of-plane speed |vy |. Vector component values are generated by fitting streaks to a model of image formation that incorporates equations of motion in 3D space. We demonstrate cross-sectional estimation of (vx ,|vy |,vz ) in two important animal models in ciliary biology: Xenopus embryos (tadpoles) and mouse trachea.

  4. Label free imaging system for measuring blood flow speeds using a single multi-mode optical fiber (Conference Presentation)

    Science.gov (United States)

    Sigal, Iliya; Caravaca Aguirre, Antonio M.; Gad, Raanan; Piestun, Rafael; Levi, Ofer

    2016-03-01

    We demonstrate a single multi-mode fiber-based micro-endoscope for measuring blood flow speeds. We use the transmission-matrix wavefront shaping approach to calibrate the multi-mode fiber and raster-scan a focal spot across the distal fiber facet, imaging the cross-polarized back-reflected light at the proximal facet using a camera. This setup allows assessment of the backscattered photon statistics: by computing the mean speckle contrast values across the proximal fiber facet we show that spatially-resolved flow speed maps can be inferred by selecting an appropriate camera integration time. The proposed system is promising for minimally-invasive studies of neurovascular coupling in deep brain structures.

  5. Nonlinear interactions between the pumping kinetics, fluid dynamics and optical resonator of cw fluid flow lasers. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Sentman, L.H.; Nayfeh, M.H.

    1983-12-01

    This research is an integrated theoretical and experimental investigation of the nonlinear interactions which may occur between the chemical kinetics, the fluid dynamics and the unstable resonator of a continuous wave fluid flow laser. The objectives of this grant were to measure the frequency and amplitude of the time dependent pulsations in the power spectral output which have been predicted to occur in cw chemical lasers employing unstable resonators to extract power.

  6. 基于光流的自主移动机器人避障系统%Autonomous Mobile Robot Obstacle Avoidance System Based on Optical Flow

    Institute of Scientific and Technical Information of China (English)

    肖雪; 秦贵和; 陈筠翰

    2013-01-01

    Since real-time obstacle avoidance is a key part of mobile robot autonomous navigation, an autonomous mobile robot obstacle avoidance system based on optical flow is proposed. This system’s input is the image sequence grabbed by the camera on the robot in motion. The optical flow information is extracted by Pyramid Lucas-Kanade method to calculate focus of expansion and time to contact. The possible position of the obstacle is estimated with improved balance strategy. Experimental results show that this system can detect and avoid obstacles with the width larger than 10 centimeters but not cover the camera view correctly, which validates the method’s feasibility.%自主移动机器人的导航要求能实时规避障碍物。为解决该问题,提出一种基于光流的自主移动机器人避障系统。将机器人在运动过程中通过摄像头拍摄的连续图像序列作为输入,使用金字塔Lucas-Kanade方法在角点处提取光流信息求解延伸焦点和接近时间,并通过改进的平衡策略估计障碍物可能存在的位置。实验结果表明,该系统在静态场景中能正确地检测并规避宽度大于10 cm,且不完全遮挡摄像头视角的障碍物,可行性较高。

  7. Investigation of isochronal annealing on the optical properties of HWCVD amorphous silicon nitride deposited at low temperatures and low gas flow rates

    Science.gov (United States)

    Muller, T. F. G.; Jacobs, S.; Cummings, F. R.; Oliphant, C. J.; Malgas, G. F.; Arendse, C. J.

    2015-06-01

    Hydrogenated amorphous silicon nitride (a-SiNx:H) is used as anti-reflection coatings in commercial solar cells. A final firing step in the production of micro-crystalline silicon solar cells allows hydrogen effusion from the a-SiNx:H into the solar cell, and contributes to bulk passivation of the grain boundaries. In this study a-SiNx:H deposited in a hot-wire chemical vapour deposition (HWCVD) chamber with reduced gas flow rates and filament temperature compared to traditional deposition regimes, were annealed isochronally. The UV-visible reflection spectra of the annealed material were subjected to the Bruggeman Effective Medium Approximation (BEMA) treatment, in which a theoretical amorphous semiconductor was combined with particle inclusions due to the structural complexities of the material. The extraction of the optical functions and ensuing Wemple-DeDomenici analysis of the wavelength-dependent refractive index allowed for the correlation of the macroscopic optical properties with the changes in the local atomic bonding configuration, involving silicon, nitrogen and hydrogen.

  8. Exploiting the Error-Correcting Capabilities of Low Density Parity Check Codes in Distributed Video Coding using Optical Flow

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau; Søgaard, Jacob; Salmistraro, Matteo;

    2012-01-01

    . Thereafter methods for exploiting the error-correcting capabilities of the LDPCA code in DVC are investigated. The proposed frame interpolation includes a symmetric flow constraint to the standard forward-backward frame interpolation scheme, which improves quality and handling of large motion. The three......, an average bitrate saving of more than 40% is achieved compared to DISCOVER on Wyner-Ziv frames. In addition we also exploit and investigate the internal error-correcting capabilities of the LDPCA code in order to make it more robust to errors. We investigate how to achieve this goal by only modifying...

  9. Evaluation of the impact of TMIn flow rate on the structural and optical properties of InN/ZnO heterojunctions using RF-MOMBE

    Science.gov (United States)

    Chen, Wei-Chun; Chen, Hung-Pin; Kuo, Shou-Yi; Lai, Fang-I.; Hsiao, Chien-Nan; Lee, Cheng-Chung

    2017-10-01

    Indium nitride (InN) films were deposited on Al2O3 substrates with a zinc oxide (ZnO) interlayer using by radio-frequency metalorganic molecular beam epitaxy (RF-MOMBE). We evaluated the impact of the flow rate of trimethylindium (In(CH3)3, TMIn) on the structure, surface morphology, and optical and electrical properties of the films using X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis spectroscopy, and Hall measurements. The XRD results indicated that all InN films were formed from single-phase wurtzite crystals with the preferred orientations along the c-axis. The SEM images indicated that the rough surfaces of the InN films grown with TMIn flow rates less than 0.55 sccm. The TEM images showed that InN and ZnO had hexagonal structures (wurtzite) that were epitaxially grown by RF-MOMBE on the substrates. The electron concentrations ranged from 7.3 × 1019 to 2.56 × 1020 cm-3 of the InN films were measured.

  10. Hyperemic responses of the optic nerve head blood flow to chromatic equiluminant flicker are reduced by ocular hypertension and early glaucoma

    Science.gov (United States)

    Falsini, Benedetto; Riva, Charles E.; Salgarello, Tommaso; Logean, Eric; Colotto, Alberto; Giudiceandrea, Andrea

    2014-06-01

    We evaluated in ocular hypertension (OHT) and early glaucoma (EOAG) patients the optic nerve head (ONH) blood flow response (RF) to chromatic equiluminant flicker. This stimulus generates neural activity dominated by the parvo-cellular system. Eleven EOAG, 20 OHT patients, and 8 age-matched control subjects were examined. The blood flow (F) at the neuroretinal rim was continuously monitored by laser Doppler flowmetry before, during, and after a 60-s exposure to a 4 Hz, red-green equiluminant flicker stimulus (30 deg field). RF was expressed as percentage F-change during the last 20 s of flicker relative to baseline F. Responses were collected at a number of temporal sites. The highest RF value was used for subsequent analysis. As compared to controls, both OHT and EOAG patients showed a decrease (pRF. We conclude that RF elicited by chromatic equiluminant flicker is abnormally reduced in OHT and EOAG patients indicating an impairment of the parvo-cellular-mediated vasoactivity. This decrease of vascular response may occur independently of neural activity loss early in the disease process.

  11. Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps (Conference Presentation)

    Science.gov (United States)

    Huang, Chong; Radabaugh, Jeffrey P.; Aouad, Rony K.; Lin, Yu; Gal, Thomas J.; Patel, Amit B.; Valentino, Joseph; Shang, Yu; Yu, Guoqiang

    2016-02-01

    Head and neck cancer accounts for 3 to 5% of all cancers in the United States. Primary or salvage surgeries are extensive and often lead to major head and neck defects that require complex reconstructions with local, regional, or free tissue transfer flaps. Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning '1') for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89 +/- 0.15, 2.26 +/- 0.13, and 2.43 +/- 0.13 (mean +/- standard error) respectively on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (p flap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flap were 1.14 and 1.34 respectively on postoperative days 2 and 4, indicating a less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

  12. Optical spectroscopy of EX Lupi during quiescence and outburst: Infall, wind, and dynamics in the accretion flow

    CERN Document Server

    Sicilia-Aguilar, Aurora; Setiawan, Johny; Ábrahám, Péter; Dullemond, Cornelis; Eiroa, Carlos; Goto, Miwa; Henning, Thomas; Júhasz, Attila

    2012-01-01

    We explore the accretion mechanisms in EX Lupi, prototype of EXor variables, during its quiescence and outburst phases. We analyse high-resolution optical spectra taken before, during, and after its 2008 outburst. In quiescence and outburst, the star presents many permitted emission lines, including typical CTTS lines and numerous neutral and ionized metallic lines. During the outburst, the number of emission lines increases to over a thousand, with narrow plus broad component structure (NC+BC). The BC profile is highly variable on short timescales (24-72h). An active chromosphere can explain the metallic lines in quiescence and the outburst NC. The dynamics of the BC line profiles suggest an origin in a hot, dense, non-axisymmetric, and non-uniform accretion column that suffers velocity variations along the line-of-sight on timescales of days. Assuming Keplerian rotation, the emitting region would be located at ~0.1-0.2 AU, consistent with the inner disk rim, but the velocity profiles of the lines reveal a c...

  13. Absorption-Modulated Crossed-Optical Fiber-Sensor Platform for Measurements in Liquid Environments and Flow Streams

    Directory of Open Access Journals (Sweden)

    Paul E. Henning

    2017-01-01

    Full Text Available A new evanescent-wave fiber sensor is described that utilizes absorption-modulated luminescence (AML in combination with a crossed-fiber sensor platform. The luminescence signals of two crossed-fiber reference regions, placed on opposite sides of the stretch of fiber supporting the absorbance sensor, monitor the optical intensity in the fiber core. Evanescent absorption of the sensor reduces a portion of the excitation light and modulates the luminescence of the second reference region. The attenuation is determined from the luminescence intensity of both reference regions similar to the Beer-Lambert Law. The AML-Crossed-Fiber technique was demonstrated using the absorbance of the Zn(II-PAN2 complex at 555 nm. A linear response was obtained over a zinc(II concentration range of 0 to 20 μM (approximately 0 to 1.3 ppm. A nonlinear response was observed at higher zinc(II concentrations and was attributed to depletion of higher-order modes in the fiber. This was corroborated by the measured induced repopulation of these modes.

  14. Structural and optical characterization of CuInS2 quantum dots synthesized by microwave-assisted continuous flow methods

    Science.gov (United States)

    Fitzmorris, Robert C.; Oleksak, Richard P.; Zhou, Zheng; Mangum, Benjamin D.; Kurtin, Juanita N.; Herman, Gregory S.

    2015-07-01

    Semiconductor quantum dots (QDs) have recently been incorporated into consumer displays and lighting technologies. Now that these materials are being produced on industrial scales, it is important to investigate scalable synthetic methods and less toxic materials and chemistries. To achieve these goals, we have synthesized cadmium-free, visible light-emitting QDs using a microwave-assisted continuous flow reactor. After synthesis, the CuInS2 QD cores underwent a near-complete Zn cation exchange reaction in a batch reactor, followed by the growth of a ZnS shell. Analysis of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy data indicate that the crystal structure changes from CuInS2 (chalcopyrite) to ZnS (zincblende) during the cation exchange reaction. Compositional analysis indicated that the core/shell QDs were 98 % ZnS, with Cu and In present at much lower concentrations. The photoluminescence (PL) peak position was blue shifted for longer cation exchange reactions, and it was found that the ZnS shell was necessary for improved PL stability. The synthesized QDs have a PL down conversion efficiency of 65 % when using a blue LED source.

  15. Natural history of optical coherence tomography-detected non-flow-limiting edge dissections following drug-eluting stent implantation

    DEFF Research Database (Denmark)

    Radu, Maria D; Räber, Lorenz; Heo, Jungho

    2014-01-01

    . The median longitudinal dissection length was 2.9 mm (interquartile range [IQR] 1.6-4.2 mm), whereas the circumferential and axial extensions amounted to 1.2 mm (IQR: 0.9-1.7 mm) and 0.6 mm (IQR: 0.4-0.7 mm), respectively. Dissections extended into the media and adventitia in seven (33%) and four (20%) cases......, and clinical outcomes were assessed. Sixty-three lesions (57 patients) were studied with OCT at baseline and one-year follow-up. Twenty-two non-flow-limiting edge dissections in 21 lesions (20 patients) were identified by OCT; only two (9%) were angiographically visible. Flaps were found in 96% of cases...... healed on OCT. The two cases exhibiting persistent dissection had the longest flaps (2.81 mm and 2.42 mm) at baseline. CONCLUSIONS: OCT-detected edge dissections which are angiographically silent in the majority of cases are not associated with acute stent thrombosis or restenosis up to one-year follow-up....

  16. A Paralleled Scheme for Computing the Multigrid Optical Flow%一种新型的并行化多栅光流计算实现方法

    Institute of Scientific and Technical Information of China (English)

    乔峰

    2015-01-01

    The new trends in computer architecture show that parallel processing is getting into some new areas of computing by using the many-core processors and multi-core embedded chips. It means that the traditional areas have to use the parallel programming to develop applications and especially useful in the biomedical image processing. This paper investigates parallelism and scalability on computing multigrid optical flow. The major challenges are to extract enough parallelism from the serial application and to improve scalability. It is difficult to use traditionally multithread programming method to develop the application. Fortunately, Intel’s Concurrent Collections (CnC), TBB, ArBB and Cilk++ multi-core programming models are now available. We use simple and effective CnC programming model to modeling the multigrid optical flow computing. We describe how to use CnC to implement a high-performance mulitgrid optical flow application and compare it against existing approaches. On a platform with two Xeon Processor X5460 3.16GHz 8-core CPUs, the parallelized solution exceeded serial codes performance by up to 6x. Our performance compared with alternative parallelized solutions, including ArBB, Cilk++ and SIMD. Our approach got around 10%performance gain compared to the existing performance of the paralleled implementation approach of SIMD, ArBB and Cilk++.%计算机架构发展的新趋势表明,并行处理正在进入通过许多核心处理器和多核嵌入式芯片进行计算的新领域,这意味着传统的计算机领域必须使用并行编程开发应用程序,特别是在生物医学图像处理领域并行应用程序将起到关键的作用。本论文研究了多栅光流计算的并行性和可扩展性。主要难点是从串行程序中提取完成并行计算需要的足够多的并行性,并提高可扩展性。目前我们很难使用现有的多线程编程方法来开发应用程序。幸好Intel公司推出CnC, TBB ArBB和Cilk++多核

  17. 光流法在机车安全行驶中的应用%Application of optical flow in locomotive safe driving

    Institute of Scientific and Technical Information of China (English)

    严强; 黄增喜; 曹丽萍; 黄蓉刚

    2013-01-01

    在基于路况视频的机车安全行驶中,依据轨道与信号灯的相对位置先验知识可缩小信号灯检测范围,提高信号灯检测的效率和可靠性,但在某些复杂光照条件下(尤其是夜间)因检测不到轨道而无法提供信号灯区域信息.针对此问题,提出一种基于光流的信号灯区域预测方法,首先在感兴趣区域中使用KLT算子提取强角点,并采用基于金字塔的Lucas-Kanade光流法计算强角点光流;然后根据全局光流信息判断机车转向状态;最后结合转向状态与先验知识估计出信号灯区域.此外,还提出了利用转向状态进行轨道跟踪检错的方法,该方法可及时发现轨道跟踪错误并唤醒系统进行轨道重定位.实验表明,该方法能有效预测信号灯区域,使信号灯检测实时性更高,抗干扰能力更强.%In the video-based locomotive safe driving assistant system, reducing the detecting region of signal light according to the location of rails and some prior knowledge can improve the efficiency and reliability of signal light detection. But it possibly fails to detect rail in some complicated illumination environments (especially in the night) , and the signal light detecting region cannot be available. To solve this problem, this paper proposed an optical flow based approach for signal light region prediction. Firstly, it got the strong corners in region of interest by KLT operators, and calculated their optical-flow using Lu-cas-Kanade method with pyramids. After that it could get the locomotive turning state from the optical flow statistical information. In the end, it could dynamically estimate the signal light region according to the turning states and prior knowledge. Besides , it also proposed a method for rails false-tracking detecting by utilizing locomotive turning states, which could detect the tracking error timely and arouse the rails relocation. Experimental results demonstrate that the proposed method can

  18. From active shape model to active optical flow model: a shape-based approach to predicting voxel-level dose distributions in spine SBRT.

    Science.gov (United States)

    Liu, Jianfei; Wu, Q Jackie; Kirkpatrick, John P; Yin, Fang-Fang; Yuan, Lulin; Ge, Yaorong

    2015-03-07

    Prediction of achievable dose distribution in spine stereotactic body radiation therapy (SBRT) can help in designing high-quality treatment plans to maximally protect spinal cords and to effectively control tumours. Dose distributions at spinal cords are primarily affected by the shapes of adjacent planning target volume (PTV) contours. In this work, we estimate such contour effects and predict dose distributions by exploring active optical flow model (AOFM) and active shape model (ASM). We first collect a sequence of dose sub-images and PTV contours near spinal cords from fifteen SBRT plans in the training dataset. The data collection is then classified into five groups according to the PTV locations in relation to spinal cords. In each group, we randomly choose a dose sub-image as the reference and register all other sub-images to the reference using an optical flow method. AOFM is then constructed by importing optical flow vectors and dose values into the principal component analysis (PCA). Similarly, we build ASM by using PCA on PTV contour points. The correlation between ASM and AOFM is estimated via a stepwise multiple regression model. When predicting dose distribution of a new case, the group is first determined based on the PTV contour. The prediction model of the selected group is used to estimate dose distributions by mapping the PTV contours from the ASM space to the AOFM space. This method was validated on fifteen SBRT plans in the testing dataset. Analysis of dose-volume histograms revealed that the important D2%, D5%, D10% and D0.1cc dosimetric parameters of spinal cords between the prediction and the clinical plans were 11.7 ± 1.7 Gy versus 11.8 ± 1.7 Gy (p = 0.95), 10.9 ± 1.7 Gy versus 11.1 ± 1.9 Gy (p = 0.8295), 10.2 ± 1.6 Gy versus 10.1 ± 1.7 (p = 0.9036) and 11.2 ± 2.0 Gy versus 11.1 ± 2.2 Gy (p = 0.5208), respectively. Here, the ‘cord’ is the spinal cord proper (not the thecal sac) extended 5 mm inferior and superior to the involved

  19. Flowing Liquid Anode Atmospheric Pressure Glow Discharge as an Excitation Source for Optical Emission Spectrometry with the Improved Detectability of Ag, Cd, Hg, Pb, Tl, and Zn.

    Science.gov (United States)

    Greda, Krzysztof; Swiderski, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-09-06

    A novel atmospheric pressure glow discharge generated in contact with a flowing liquid anode (FLA-APGD) was developed as the efficient excitation source for the optical emission spectrometry (OES) detection. Differences in the appearance and the electrical characteristic of the FLA-APGD and a conventional system operated with a flowing liquid cathode (FLC-APGD) were studied in detail and discussed. Under the optimal operating conditions for the FLA-APGD, the emission from the analytes (Ag, Cd, Hg, Pb, Tl, and Zn) was from 20 to 120 times higher as compared to the FLC-APGD. Limits of detections (LODs) established with a novel FLA-APGD system were on average 20 times better than those obtained for the FLC-APGD. A further improvement of the LODs was achieved by reducing the background shift interferences and, as a result, the LODs for Ag, Cd, Hg, Pb, Tl, and Zn were 0.004, 0.040, 0.70, 1.7, 0.035, and 0.45 μg L(-1), respectively. The precision of the FLA-APGD-OES method was evaluated to be within 2-5% (as the relative standard deviation of the repeated measurements). The method found its application in the determination of the content of Ag, Cd, Hg, Pb, Tl, and Zn in a certified reference material (CRM) of Lobster hepatopancreas (TORT-2), four brass samples as well as mineral water and tea leaves samples spiked with the analytes. In the case of brass samples, a reference method, i.e., inductively coupled plasma optical emission spectrometry (ICP-OES) was used. A good agreement between the results obtained with FLA-APGD-OES and the certified values for the CRM TORT-2 as well as the reference values obtained with ICP-OES for the brass samples was revealed, indicating the good accuracy of the proposed method. The recoveries obtained for the spiked samples of mineral water and tea leaves were within the range of 97.5-102%.

  20. Use of an optical process for the analysis of bubble flows; Einsatz eines optischen Verfahrens zur Analyse von Blasenstroemungen

    Energy Technology Data Exchange (ETDEWEB)

    Kecke, H.J.; Wunderlich, B. [Magdeburg Univ. (Germany). Inst. fuer Stroemungstechnik und Thermodynamik

    1997-12-01

    By microscope examination, it was possible to clear up why gas bubbles give LDA signals with greater pedestal (difference between black and blank level) and greater amplitude. Both the phase boundary surface and tracer particles agglomerated on the bubble surface produce a higher uniform part. With nearly diametral passage of the bubble through the measured volume, at least the front and rear phase boundary surfaces produce an LDA signal. There is a measurement gap in between, which can be used for determining the bubble diameter. The knowledge of the proportion of both phases contained in the results of measurement is necessary to be able to determine the effect of the degree of turbulence by the bubble loading. It is proposed to carry out conversion of measured values, which will ensure that the result is independent of tracer dosing and reflects the actual proportion of gas volume flow. The aim was to find out exact information on the `pseudo turbulence` caused by the bubbles. [Deutsch] Durch Untersuchungen mittels Mikroskop konnte geklaert werden, warum Gasblasen LDA-Signale mit groesserem Pedestal und groesserer Amplitude ergeben. Sowohl die Phasengrenzflaeche als auch an der Blasenoberflaeche agglomerierte Tracerteilchen erzeugen einen hoeheren Gleichanteil. Bei annaehrend diametralem Durchgang der Blase durch das Messvolumen erzeugen zumindest die vordere und die hintere Phasengrezflaeche ein LDA-Signal. Dazwischen liegt eine Messluecke, die sich fuer die Blasendurchmesserbestimmung ausnutzen laesst. Die Kenntnis des im Messergebnis enthaltenen Anteils beider Phasen ist notwendig, um die Beeinflussung des Turbulenzgrades durch die Blasenbeladung definieren zu koennen. Es wird vorgeschlagen, Messwertumrechnungen vorzunehmen, die dafuer sorgen, dass das Ergebnis unabhaengig von der Tracerdosierung ist und den tatsaechlichen Gasvolumenstromanteil widerspiegelt. Ziel war es, eine genaue Aussage zu der durch die Blasen hervorgerufenen `Pseudoturbulenz` zu treffen

  1. Optics/Optical Diagnostics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Optics/Optical Diagnostics Laboratory supports graduate instruction in optics, optical and laser diagnostics and electro-optics. The optics laboratory provides...

  2. U.S. Air Force Research Laboratory's Need for Flow Physics and Control With Applications Involving Aero-Optics and Weapon Bay Cavities

    Science.gov (United States)

    Schmit, Ryan

    2010-01-01

    To develop New Flow Control Techniques: a) Knowledge of the Flow Physics with and without control. b) How does Flow Control Effect Flow Physics (What Works to Optimize the Design?). c) Energy or Work Efficiency of the Control Technique (Cost - Risk - Benefit Analysis). d) Supportability, e.g. (size of equipment, computational power, power supply) (Allows Designer to include Flow Control in Plans).

  3. Optical properties and bioavailability of dissolved organic matter along a flow-path continuum from soil pore waters to the Kolyma River, Siberia

    Directory of Open Access Journals (Sweden)

    K. E. Frey

    2015-08-01

    Full Text Available The Kolyma River in Northeast Siberia is among the six largest arctic rivers and drains a region underlain by vast deposits of Holocene-aged peat and Pleistocene-aged loess known as yedoma, most of which is currently stored in ice-rich permafrost throughout the region. These peat and yedoma deposits are important sources of dissolved organic matter (DOM to inland waters that in turn play a significant role in the transport and ultimate remineralization of organic carbon to CO2 and CH4 along the terrestrial flow-path continuum. The turnover and fate of terrigenous DOM during offshore transport will largely depend upon the composition and amount of carbon released to inland and coastal waters. Here, we measured the optical properties of chromophoric DOM (CDOM from a geographically extensive collection of waters spanning soil pore waters, streams, rivers, and the Kolyma River mainstem throughout a ∼ 250 km transect of the northern Kolyma River basin. During the period of study, CDOM absorbance values were found to be robust proxies for the concentration of DOM, whereas additional CDOM parameters such as spectral slopes (S were found to be useful indicators of DOM quality along the flow-path. In particular, CDOM absorption at 254 nm showed a strong relationship with dissolved organic carbon (DOC concentrations across all water types (r2 = 0.958, p SR of CDOM demonstrated statistically significant differences between all four water types and tracked changes in the concentration of bioavailable DOC, suggesting that this parameter may be suitable for clearly discriminating shifts in organic matter characteristics among water types along the full flow-path continuum across this landscape. The heterogeneity of environmental characteristics and extensive continuous permafrost of the Kolyma River basin combine to make this a critical region to investigate and monitor. With ongoing and future permafrost degradation, peat and yedoma deposits throughout the

  4. A high-density EEG study of differences between three high speeds of simulated forward motion from optic flow in adult participants

    Directory of Open Access Journals (Sweden)

    Kenneth eVilhelmsen

    2015-10-01

    Full Text Available A high-density EEG study was conducted to investigate evoked and oscillatory brain activity in response to high speeds of simulated forward motion. Participants were shown an optic flow pattern consisting of a virtual road with moving poles at either side of it, simulating structured forward motion at different driving speeds (25, 50, and 75 km/h with a static control condition between each motion condition. Significant differences in N2 latencies and peak amplitudes between the three speeds of visual motion were found in parietal channels of interest P3 and P4. As motion speed increased, peak latency increased while peak amplitude decreased which might indicate that higher driving speeds are perceived as more demanding resulting in longer latencies, and as fewer neurons in the motion sensitive areas of the adult brain appear to be attuned to such high visual speeds this could explain the observed inverse relationship between speed and amplitude. In addition, significant differences between alpha de-synchronizations for forward motion and alpha synchronizations in the static condition were found in the parietal midline (PM source. It was suggested that the alpha de-synchronizations reflect an activated state related to the visual processing of simulated forward motion, whereas the alpha synchronizations in response to the static condition reflect a deactivated resting period.

  5. Two Optical Techniques Appropriate for Visualizing the Steady/Unsteady Vortical Flow Past a Highly Swept Delta—Wing Equipped with Double Vortex—Flaps in Low and High Speed Wind—Tunnel

    Institute of Scientific and Technical Information of China (English)

    GongNI; DingdingXIN; 等

    1998-01-01

    For a better understanding of the vortical flow past a highly swept deltawing equipped with double vortex-flaps,two optical techniques including the Laser-light-sheet with artificial particals put in the test-section and the Schlieren photography were used for steady/unsteady flow visualization in the low and high speed wind-tunnel respectively.SIne these techniques are seldom used for vortical flow visualization in the mentioned cases in our country.our success has the significance to indicate that they are appropriate for visualizing the development ,mutual interaction and bresk-down of the vortices appear in the complex flow field.In this paper,besides the experimental procedure,merits and demerits of these two techniques are discussed through comparisons.

  6. Geophysical fluid flow experiment

    Science.gov (United States)

    Broome, B. G.; Fichtl, G.; Fowlis, W.

    1979-01-01

    The essential fluid flow processes associated with the solar and Jovian atmospheres will be examined in a laboratory experiment scheduled for performance on Spacelab Missions One and Three. The experimental instrumentation required to generate and to record convective fluid flow is described. Details of the optical system configuration, the lens design, and the optical coatings are described. Measurement of thermal gradient fields by schlieren techniques and measurement of fluid flow velocity fields by photochromic dye tracers is achieved with a common optical system which utilizes photographic film for data recording. Generation of the photochromic dye tracers is described, and data annotation of experimental parameters on the film record is discussed.

  7. Customization of an optical probe device and validation of a signal processing procedure to study gas-liquid-solid flows. Application to a three-phase internal-loop Gas-lift Bioreactor

    OpenAIRE

    Mota, A; Ferreira, António; Vicente, A.A.; Sechet, P.; Martins, Jean; Teixeira, J. A.; Cartellier, Alain

    2015-01-01

    The study of local hydrodynamic properties of three-phase bioreactors in biotechnology processes is of great importance, mainly because of the complex interaction between bioreactor and microorganisms. However, classical techniques used for measuring local hydrodynamic properties such as single needle probes are mainly limited to two-phase flows. In this work it was developed and validated a new system, based on the customization of an optical probe initially designed in LEGI. The necessity o...

  8. 昆虫视觉启发的光流复合导航方法%An Optical Flow-based Composite Navigation Method Inspired by Insect Vision

    Institute of Scientific and Technical Information of China (English)

    潘超; 刘建国; 李峻林

    2015-01-01

    Many insects can use optical flow (OF) for various navigational tasks. Inspired by the OF navigation strategies of insects, this paper develops an OF-based composite navigation method for more efficient and precise visual location. The composite navigation method is composed of an OF navigation and an OF aided navigation. The OF navigation is to measure motion at each step using an insect inspired OF method and the current position information is then obtained by path integration. As path integration can lead to increasing cumulative position errors, the OF aided navigation is thus employed to correct the position errors. This aided navigation implements an OF-based Kalman filter by studying the insect inspired OF method. It can iteratively match the actual and the predicted OF for a continuous error estimation. The OF navigation and the OF aided navigation are derived from the same OF method so that they can share input signals and some operations in navigation. Experiments using a mobile robot have demonstrated the efficiency of the proposed composite navigation method.%昆虫能够使用视觉感受的光流(Optical flow, OF)信息执行导航任务。启发于昆虫的视觉导航,本文提出了一种生物视觉启发的光流复合导航方法,它由光流导航和光流辅助导航两部分组成,以实现高效精确的视觉导航定位。该方法中,光流导航的作用是使用昆虫视觉启发的光流法,测量系统每一时刻的运动位移,然后使用路径积分累加位移得到位置信息;光流辅助导航的作用是针对路径积分会产生累积误差的缺点,使用光流匹配的方法来估计和修正导航中的位置误差。该光流辅助导航也参考了昆虫启发的光流法,通过基于光流的卡尔曼滤波器来执行实际和预测光流的迭代匹配。由于光流导航和光流辅助导航中的光流计算来源于同一昆虫启发光流法,使得光流复合导航的两部分可共享输入信号和部分

  9. Actively heated high-resolution fiber-optic-distributed temperature sensing to quantify streambed flow dynamics in zones of strong groundwater upwelling

    Science.gov (United States)

    Briggs, Martin A.; Buckley, Sean F.; Bagtzoglou, Amvrossios C.; Werkema, Dale D.; Lane, John W.

    2016-07-01

    Zones of strong groundwater upwelling to streams enhance thermal stability and moderate thermal extremes, which is particularly important to aquatic ecosystems in a warming climate. Passive thermal tracer methods used to quantify vertical upwelling rates rely on downward conduction of surface temperature signals. However, moderate to high groundwater flux rates (>-1.5 m d-1) restrict downward propagation of diurnal temperature signals, and therefore the applicability of several passive thermal methods. Active streambed heating from within high-resolution fiber-optic temperature sensors (A-HRTS) has the potential to define multidimensional fluid-flux patterns below the extinction depth of surface thermal signals, allowing better quantification and separation of local and regional groundwater discharge. To demonstrate this concept, nine A-HRTS were emplaced vertically into the streambed in a grid with ˜0.40 m lateral spacing at a stream with strong upward vertical flux in Mashpee, Massachusetts, USA. Long-term (8-9 h) heating events were performed to confirm the dominance of vertical flow to the 0.6 m depth, well below the extinction of ambient diurnal signals. To quantify vertical flux, short-term heating events (28 min) were performed at each A-HRTS, and heat-pulse decay over vertical profiles was numerically modeled in radial two dimension (2-D) using SUTRA. Modeled flux values are similar to those obtained with seepage meters, Darcy methods, and analytical modeling of shallow diurnal signals. We also observed repeatable differential heating patterns along the length of vertically oriented sensors that may indicate sediment layering and hyporheic exchange superimposed on regional groundwater discharge.

  10. Sensitive determination of mercury in tap water by cloud point extraction pre-concentration and flow injection-cold vapor-inductively coupled plasma optical emission spectrometry

    Science.gov (United States)

    de Wuilloud, Jorgelina C. A.; Wuilloud, Rodolfo G.; Silva, María. F.; Olsina, Roberto A.; Martinez, Luis D.

    2002-02-01

    A pre-concentration and determination methodology for mercury at trace levels in water samples was developed. Cloud point extraction was successfully employed for the pre-concentration of mercury prior to inductively coupled plasma optical emission spectrometry coupled to a flow injection with cold vapor generation system. The mercury was extracted as mercury-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol [Hg(II)-(5-Br-PADAP)] complex, at pH 9.2 mediated by micelles of the non-ionic surfactant polyethyleneglycolmono- p-nonylphenylether (PONPE 5). Cold vapor generation was developed from 100 μl of the extracted surfactant-rich phase by means of a stannous chloride (SnCl 2) solution as reluctant. An exhaustive study of the variables affecting the cloud point extraction with PONPE 5 and cold vapor mercury generation from the surfactant phase was performed. The 50-ml sample solution pre-concentration allowed us to raise an enrichment factor of 200-fold. The lower limit of detection obtained under the optimal conditions was 4 ng l -1. The precision for 10 replicate determinations at the 0.5-μg l -1 Hg level was 3.4% relative standard deviation (R.S.D.), calculated with the peak heights. The calibration graph using the pre-concentration system for mercury was linear with a correlation coefficient of 0.9998 at levels near the detection limits up to at least 50 μg l -1. The method was successfully applied to the determination of mercury in tap water samples.

  11. Optical flow and image segmentation analysis for noninvasive precise mapping of microwave thermal ablation in X-ray CT scans - ex vivo study.

    Science.gov (United States)

    Ziv, Omri; Goldberg, S Nahum; Nissenbaum, Yitzhak; Sosna, Jacob; Weiss, Noam; Azhari, Haim

    2017-09-20

    To develop image processing algorithms for noninvasive mapping of microwave thermal ablation using X-ray CT. Ten specimens of bovine liver were subjected to microwave ablation (20-80 W, 8 min) while scanned by X-ray CT at 5 s intervals. Specimens were cut and manually traced by two observers. Two algorithms were developed and implemented to map the ablation zone. The first algorithm utilises images segmentation of Hounsfield units changes (ISHU). The second algorithm utilises radial optical flow (ROF). Algorithm sensitivity to spatiotemporal under-sampling was assessed by decreasing the acquisition rate and reducing the number of acquired projections used for image reconstruction in order to evaluate the feasibility of implementing radiation reduction techniques. The average radial discrepancy between the ISHU and ROF contours and the manual tracing were 1.04±0.74 and 1.16±0.79mm, respectively. When diluting the input data, the ISHU algorithm retained its accuracy, ranging from 1.04 to 1.79mm. By contrast, the ROF algorithm performance became inconsistent at low acquisition rates. Both algorithms were not sensitive to projections reduction, (ISHU: 1.24±0.83mm, ROF: 1.53±1.15mm, for reduction by eight fold). Ablations near large blood vessels affected the ROF algorithm performance (1.83±1.30mm; p mapping algorithms can provide highly accurate contouring of the ablation zone at low scan rates. The ISHU algorithm may be more suitable for clinical practice as it appears more robust when radiation dose reduction strategies are employed and when the ablation zone is near large blood vessels.

  12. Unsteady flow through in-vitro models of the glottis

    Science.gov (United States)

    Hofmans, G. C. J.; Groot, G.; Ranucci, M.; Graziani, G.; Hirschberg, A.

    2003-03-01

    The unsteady two-dimensional flow through fixed rigid in vitro models of the glottis is studied in some detail to validate a more accurate model based on the prediction of boundary-layer separation. The study is restricted to the flow phenomena occurring within the glottis and does not include effects of vocal-fold movement on the flow. Pressure measurements have been carried out for a transient flow through a rigid scale model of the glottis. The rigid model with a fixed geometry driven by an unsteady pressure is used in order to achieve a high accuracy in the specification of the geometry of the glottis. The experimental study is focused on flow phenomena as they might occur in the glottis, such as the asymmetry of the flow due to the Coanda effect and the transition to turbulent flow. It was found that both effects need a relatively long time to establish themselves and are therefore unlikely to occur during the production of normal voiced speech when the glottis closes completely during part of the oscillation cycle. It is shown that when the flow is still laminar and symmetric the prediction of the boundary-layer model and the measurement of the pressure drop from the throat of the glottis to the exit of the glottis agree within 40%. Results of the boundary-layer model are compared with a two-dimensional vortex-blob method for viscous flow. The difference between the results of the simpiflied boundary-layer model and the experimental results is explained by an additional pressure difference between the separation point and the far field within the jet downstream of the separation point. The influence of the movement of the vocal folds on our conclusions is still unclear.

  13. New method of 3D detection based on straight-line optical flow%基于直线光流场的三维检测新方法

    Institute of Scientific and Technical Information of China (English)

    陈震; 许强; 闫军; 江少锋

    2012-01-01

    提出了基于直线光流场的三维检测计算方法.在透视投影下,将表示二维直线的参数对时间的导数定义成直线光流场,详细推导出基于直线光流场检测三维刚体运动参数的模型.使用最小二乘法,求出刚体的三维旋转运动参数、平移运动参数和空间直线坐标,从而实现了刚体的三维检测.该方法利用单目图像序列中连续3幅图像的2对直线光流,能够检测出物体的运动参数和结构参数,有助于全面检测和识别物体.多组实验表明该方法是稳定的,具有较好的鲁棒性能.%In this paper, a new method of solving 3D rigid body motion and structure based on straight-light optical flow is proposed. Under the perspective projection, the derivatives of the three parameters of a 2D line to time are defined as the straight-line optical flow; and the motion parameter model of a 3D rigid body based on straight-line optical flow is established. The rotation motion parameters, translational motion parameters and 3D coordinates of the 3D rigid body can be solved. In order to detect and recognize the details, the presented algorithm uses two pairs of straight-line optical flows of three consecutive image frames in the image sequence and can reconstruct the 3D motion and structure parameters from the straight-line optical flows. Experiments on synthesized image sequences and real image sequences show that this method is stable and robust.

  14. Collective flow in ultrarelativistic 3He–Au collisions

    Directory of Open Access Journals (Sweden)

    Piotr Bożek

    2014-12-01

    Full Text Available The triangular flow in ultrarelativistic 3He–Au collisions at RHIC energies is enhanced due to the triangular arrangement of the nucleon configurations in 3He. We study the fireball eccentricities in the Glauber Monte Carlo model and find that since the configurations of the projectile 3He are elongated triangles, the created fireball has not only a significant triangularity but also a large ellipticity. The dependence of the triangularity on centrality is weak, so it cannot be extracted from the centrality dependence of the triangular flow v3, as it is dominated by the centrality dependence of the hydrodynamic response. We propose to look at the centrality dependence of the ratio vn{4}/vn{2}, where the uncertainties from the hydrodynamic response cancel, and show that the basic signature of the geometry-driven collective flow is the rise of the ratio v3{4}/v3{2} with the number of participant nucleons for centralities less than 10%.

  15. Antibody Immobilization on Waveguides Using aFlow–Through System Shows Improved Listeria monocytogenesDetection in an Automated Fiber Optic Biosensor: RAPTORTM

    Directory of Open Access Journals (Sweden)

    Arun K. Bhunia

    2006-08-01

    Full Text Available Recent outbreaks of food borne illnesses continue to support the need for rapidand sensitive methods for detection of foodborne pathogens. A method for detecting Listeriamonocytogenes in food samples was developed using an automated fiber-optic-basedimmunosensor, RAPTORTM. Detection of L. monocytogenes in phosphate buffered saline(PBS was performed to evaluate both static and flow through antibody immobilizationmethods for capture antibodies in a sandwich assay. Subsequent detection in frankfurtersamples was conducted using a flow through immobilization system. A two stage blockingusing biotinylated bovine serum albumin (b-BSA and BSA was effectively employed toreduce the non-specific binding. The sandwich assay using static or flow through mode ofantibody immobilization could detect 1

  16. Optic glioma

    Science.gov (United States)

    Glioma - optic; Optic nerve glioma; Juvenile pilocytic astrocytoma; Brain cancer - optic glioma ... Optic gliomas are rare. The cause of optic gliomas is unknown. Most optic gliomas are slow-growing ...

  17. Photometric flow injection determination of phosphate on a PDMS microchip using an optical detection system assembled with an organic light emitting diode and an organic photodiode.

    Science.gov (United States)

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-01-01

    A compact photometric detector was constructed from an organic light emitting diode (OLED) based on a europium complex, europium(diben-zoylmethanato)3(bathophenanthroline) (Eu(DBM)3bath), as the light source and an organic photodiode (OPD) fabricated from a hetero-junction of two layers of copper phthalocyanine (CuPc)/fullerene (C60) as the photo-detector on a microchip prepared from poly(dimethylsiloxan) (PDMS) and was applied to the determination of phosphate. The OLED and the OPD were fabricated by a vapor deposition method on an indium tin oxide (ITO) coated glass substrate with the following layered structure; Glass (0.7 mm)/ITO (110 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl amino]-biphenyl (α-NPD) (30 nm)/4,4'-di(N-carbazolyl)biphenyl (CBP): Eu(3+) (8 wt%, 30 nm)/bathocuproine (BCP) (30 nm)/aluminum tris(8-hydroxyquinoline) (Alq3) (25 nm)/magnesium and silver (MgAg) (100 nm)/Ag (10nm) and Glass (0.7 mm)/ITO (110 nm)/CuPc (35 nm)/C60 (50 nm)/BCP (10 nm)/Ag (50 nm), respectively. The OLED based on the europium complex emitted a sharp light at the wavelength of 612 nm with a full width at half maximum (FWHM) of 8 nm. The performance of the photometric detector assembled was evaluated based on measurements of the absorbance of different concentrations of malachite green (MG) solutions for a batch system with 1cm long path length. The molar absorptive coefficient of the MG solution, calculated from the photocurrent of the OPD, was in good agreement with the value reported in the literature. A microchip with two inlets and one outlet U-shaped channel was prepared by a conventional photolithograph method. The OLED and the OPD were configured so as to face each other through the PDMS microchip in parallel in order to align the light axis of the OLED and the OPD with the flow cell (optical path length of 5mm), which was located at the end of outlet. For the determination of phosphate, an ion-association reaction between MG and a molybdenum-phosphate complex was utilized

  18. Methane Flow Rate Effects On The Optical Properties of Amorphous Silicon Carbon (a-SiC:H Films Deposited By DC Sputtering Methods

    Directory of Open Access Journals (Sweden)

    Rosari Saleh

    2002-04-01

    Full Text Available We have investigated the refractive index (n and the optical absorption coeffi cient (α from refl ection and transmission measurements on hydrogenated amorphous silicon carbon (a-SiC:H fi lms. The a-SiC:H fi lms were prepared by dc sputtering method using silicon target in argon and methane gas mixtures. The refractive index (n decreases as the methane fl ow rate increase. The optical absorption coeffi cient (α shifts to higher energy with increasing methane fl ow rate. At higher methane fl ow rate, the fi lms tend to be more disorder and have wider optical gap. The relation of the optical properties and the disorder amorphous network with the compositional properties will be discussed.

  19. Stage-specific activity of potential antimalarial compounds measured in vitro by flow cytometry in comparison to optical microscopy and hypoxanthine uptake

    Directory of Open Access Journals (Sweden)

    Carmen E Contreras

    2004-03-01

    Full Text Available The evaluation of new antimalarial agents using older methods of monitoring sensitivity to antimalarial drugs are laborious and poorly suited to discriminate stage-specific activity. We used flow cytometry to study the effect of established antimalarial compounds, cysteine protease inhibitors, and a quinolone against asexual stages of Plasmodium falciparum. Cultured P. falciparum parasites were treated for 48 h with different drug concentrations and the parasitemia was determined by flow cytometry methods after DNA staining with propidium iodide. P. falciparum erythrocytic life cycle stages were readily distinguished by flow cytometry. Activities of established and new antimalarial compounds measured by flow cytometry were equivalent to results obtained with microscopy and metabolite uptake assays. The antimalarial activity of all compounds was higher against P. falciparum trophozoite stages. Advantages of flow cytometry analysis over traditional assays included higher throughput for data collection, insight into the stage-specificity of antimalarial activity avoiding use of radioactive isotopes.

  20. Optical linear algebra

    Energy Technology Data Exchange (ETDEWEB)

    Casasent, D.; Ghosh, A.

    1983-01-01

    Many of the linear algebra operations and algorithms possible on optical matrix-vector processors are reviewed. Emphasis is given to the use of direct solutions and their realization on systolic optical processors. As an example, implicit and explicit solutions to partial differential equations are considered. The matrix-decomposition required is found to be the major operation recommended for optical realization. The pipelining and flow of data and operations are noted to be key issues in the realization of any algorithm on an optical systolic array processor. A realization of the direct solution by householder qr decomposition is provided as a specific case study. 19 references.

  1. 基于AdaBoost算法和光流匹配的实时手势识别%Real-time Gesture Recognition Based on AdaBoost Algorithm and Optical Flow Matching

    Institute of Scientific and Technical Information of China (English)

    王凯; 于鸿洋; 张萍

    2012-01-01

    着眼于更宽泛和更便捷的应用需要,提出了基于AdaBoost算法和光流匹配的实时手势识别方案.只需连接到计算机的摄像头读取二维手势视频片段就能对手势作为较为准确的识别.其中,采用AdaBoost算法遍历图像,完成静态手势的识别工作;在动态手势的识别过程中,运用了光流法结合模板匹配的方法.整个系统对静态和动态手势的识别均具有较强的鲁棒性.%Focusing on more general and more convenient application, a novel real-time gesture recognition method based on AdaBoost algorithm and optical flow matching was put forward. In detail, the AdaBoost algorithm was used to traverse the whole image for the recognition of static gestures. As to the dynamic gestures, the method combining optical flow with template matching was utilized. The whole system has strong robustness in the recognition of both static and dynamic gestures.

  2. Whether radial receptive field organization of the fourth extrastriate crescent (area V4A) gives special advantage for analysis of the optic flow. Comparison with the first crescent (area V2).

    Science.gov (United States)

    Levichkina, E V; Loshkarev, A A; Rodionova, E I; Popova, E P; Pigarev, I N

    2007-09-01

    Recently, elongated comet-shaped receptive fields were discovered in the fourth extrastriate crescent (area V4A) of cats and monkeys. It was shown that the long axes of these receptive fields were oriented radially toward the centre of the retina. Such unusual "radial" organization of this extrastriate area led to the assumption that these neurons may contribute to the analysis of optic flow. To investigate this assumption we recorded activity of neurons in the V4A of cats during real motion in depth toward or away from a stationary visual scene. Responses of neurons in area V4A were compared with activity of neurons in area V2 under similar conditions of stimulation. Area V2 is known to be sensitive to motion but does not have radial organization. It was found that a substantial number of visual neurons in both areas did not fire at all when cats were exposed to motion in depth. Nevertheless, neurons with selective activation to direction of motion in depth were identified, but comparable numbers were found in both areas studied. We conclude that radial organization of the fourth extrastriate crescent does not provide any special advantage for the analysis of optic flow information.

  3. 累积方向-数量级光流梯度直方图的人体动作识别%Human action recognition based on accumulated orientation-magnitude histograms of optical flow

    Institute of Scientific and Technical Information of China (English)

    郭利; 曹江涛; 李平; 姬晓飞

    2014-01-01

    In order to improve the recognition rate and efficiency of optical flow in the human action recognition sys-tem, a novel method for human action representation based on the accumulated orientation-magnitude gradient his-tograms of the optical flow is proposed in this paper .First the image optical flow is computed , and then every flow vector is counted according to the orientation-magnitude to obtain orientation-magnitude histograms of single frame image.Finally information of the video sequence can be represented by accumulating orientation-magnitude histo-grams in time dimension .The proposed feature is evaluated on a standard database of human actions:KTH.The ex-periment conducted on the four scenes demonstrates that this algorithm is effective and achieves a correct recogni -tion rate of 87.5%with the KTH dataset .%为了提高光流信息在人体动作识别系统中应用的效果和效率,提出一种累计方向-数量级光流梯度直方图的人体动作特征表示方法。该方法首先利用Horn-Schunck充流算法计算图像光流,然后将光流矢量按照不同的方向-数量级进行直方图统计,得到单帧图像的方向-数量级的光流梯度直方图,最后将单帧图像的直方图特征在时间维上进行累积来表示整个视频动作的特征。利用该特征在KTH动作视频库上进行动作识别测试,4个场景的混合测试得到了87.5%的平均正确识别率,验证了算法的有效性。

  4. Retinal flow cytometer.

    Science.gov (United States)

    Alt, C; Veilleux, I; Lee, H; Pitsillides, C M; Côté, D; Lin, C P

    2007-12-01

    The in vivo flow cytometer is an instrument capable of continuous, real-time monitoring of fluorescently labeled cells in the circulation without the need to draw blood samples. However, the original system probes a single vessel in the mouse ear; the small sample volume limits the sensitivity of the technique. We describe an in vivo retinal flow cytometer that simultaneously probes five artery-vein pairs in the mouse eye by circularly scanning a small laser spot rapidly around the optic nerve head. We demonstrate that the retinal flow cytometer detects about five times more cells per minute than the original in vivo flow cytometer does in the ear.

  5. 相干光断层血管成像在青光眼视盘血流检测中的应用%The application of angio-OCT in optic disc blood flow detection of glaucoma

    Institute of Scientific and Technical Information of China (English)

    董秀芬; 钟华

    2016-01-01

    相干光断层血管成像(optical coherence tomography angiography,Angio-OCT)是一种新型的、无创性的眼底血管造影方法,能够为视网膜、黄斑区及视盘提供高分辨率、分层分析的图像。其围绕视盘及视盘旁视网膜毛细血管的测量可实现对青光眼的诊断及严重程度分级,并且 Angio-OCT 首次在活体上实现对视盘的血流分析达到组织解剖水平,为青光眼发病机制的研究提供证据,特别是对青光眼血管学说具有重要的意义。(国际眼科纵览,2016,40:145-150)%Angio-OCT is a new,noninvasive imaging technique that provides high-resolution,en-face images of the retinal,macular area and the optic nerve head.Angio-OCT could be applied to glaucoma-tous diagnosis and severity classification depending on measurement of capillary circulation in the optic disc and peripapillary retina,which first achieved anatomical level in the blood flow of optic disc analysis in vivo that provides evidence for the understanding of the pathogenesis in glaucoma and has important significance in vascular theory.(Int Rev Ophthalmol,2016,40:145-150)

  6. Changing image of correlation optics: introduction

    DEFF Research Database (Denmark)

    Angelsky, Oleg V.; Desyatnikov, Anton S.; Gbur, Gregory J.;

    2016-01-01

    This feature issue of Applied Optics contains a series of selected papers reflecting recent progress of correlation optics and illustrating current trends in vector singular optics, internal energy flows at light fields, optical science of materials, and new biomedical applications of lasers. (C)...

  7. Changing image of correlation optics: introduction.

    Science.gov (United States)

    Angelsky, Oleg V; Desyatnikov, Anton S; Gbur, Gregory J; Hanson, Steen G; Lee, Tim; Miyamoto, Yoko; Schneckenburger, Herbert; Wyant, James C

    2016-04-20

    This feature issue of Applied Optics contains a series of selected papers reflecting recent progress of correlation optics and illustrating current trends in vector singular optics, internal energy flows at light fields, optical science of materials, and new biomedical applications of lasers.

  8. Changing image of correlation optics: introduction

    DEFF Research Database (Denmark)

    Angelsky, Oleg V.; Desyatnikov, Anton S.; Gbur, Gregory J.

    2016-01-01

    This feature issue of Applied Optics contains a series of selected papers reflecting recent progress of correlation optics and illustrating current trends in vector singular optics, internal energy flows at light fields, optical science of materials, and new biomedical applications of lasers. (C...

  9. Geometry-driven cell organization determines tissue growths in scaffold pores: consequences for fibronectin organization.

    Directory of Open Access Journals (Sweden)

    Pascal Joly

    Full Text Available To heal tissue defects, cells have to bridge gaps and generate new extracellular matrix (ECM. Macroporous scaffolds are frequently used to support the process of defect filling and thus foster tissue regeneration. Such biomaterials contain micro-voids (pores that the cells fill with their own ECM over time. There is only limited knowledge on how pore geometry influences cell organization and matrix production, even though it is highly relevant for scaffold design. This study hypothesized that 1 a simple geometric description predicts cellular organization during pore filling at the cell level and that 2 pore closure results in a reorganization of ECM. Scaffolds with a broad distribution of pore sizes (macroporous starPEG-heparin cryogel were used as a model system and seeded with primary fibroblasts. The strategies of cells to fill pores could be explained by a simple geometrical model considering cells as tensioned chords. The model matched qualitatively as well as quantitatively by means of cell number vs. open cross-sectional area for all pore sizes. The correlation between ECM location and cell position was higher when the pores were not filled with tissue (Pearson's coefficient ρ = 0.45±0.01 and reduced once the pores were closed (ρ = 0.26±0.04 indicating a reorganization of the cell/ECM network. Scaffold pore size directed the time required for pore closure and furthermore impacted the organization of the fibronectin matrix. Understanding how cells fill micro-voids will help to design biomaterial scaffolds that support the endogenous healing process and thus allow a fast filling of tissue defects.

  10. Patient geometry-driven information retrieval for IMRT treatment plan quality control.

    Science.gov (United States)

    Wu, Binbin; Ricchetti, Francesco; Sanguineti, Giuseppe; Kazhdan, Misha; Simari, Patricio; Chuang, Ming; Taylor, Russell; Jacques, Robert; McNutt, Todd

    2009-12-01

    Intensity modulated radiation therapy (IMRT) treatment plan quality depends on the planner's level of experience and the amount of time the planner invests in developing the plan. Planners often unwittingly accept plans when further sparing of the organs at risk (OARs) is possible. The authors propose a method of IMRT treatment plan quality control that helps planners to evaluate the doses of the OARs upon completion of a new plan. It is achieved by comparing the geometric configurations of the OARs and targets of a new patient with those of prior patients, whose plans are maintained in a database. They introduce the concept of a shape relationship descriptor and, specifically, the overlap volume histogram (OVH) to describe the spatial configuration of an OAR with respect to a target. The OVH provides a way to infer the likely DVHs of the OARs by comparing the relative spatial configurations between patients. A database of prior patients is built to serve as an external reference. At the conclusion of a new plan, planners search through the database and identify related patients by comparing the OAR-target geometric relationships of the new patient with those of prior patients. The treatment plans of these related patients are retrieved from the database and guide planners in determining whether lower doses delivered to the OARs in the new plan are feasible. Preliminary evaluation is promising. In this evaluation, they applied the analysis to the parotid DVHs of 32 prior head-and-neck patients, whose plans are maintained in a database. Each parotid was queried against the other 63 parotids to determine whether a lower dose was possible. The 17 parotids that promised the greatest reduction in D50 (DVH dose at 50% volume) were flagged. These 17 parotids came from 13 patients. The method also indicated that the doses of the other nine parotids of the 13 patients could not be reduced, so they were included in the replanning process as controls. Replanning with an effort to reduce D50 was conducted on these 26 parotids. After replanning, the average reductions for D50 of the 17 flagged parotids and nine unflagged parotids were 6.6 and 1.9 Gy, respectively. These results demonstrate that the quality control method has accurately identified not only the parotids that require dose reductions but also those for which dose reductions are marginal. Originally, 11 of out the 17 flagged parotids did not meet the Radiation Therapy Oncology Group sparing goal of V(30 Gy) plans were compared to those of the replans by using pairwise Wilcoxon p test. The statistical comparisons show that replanning compromised neither PTV coverage nor OAR sparing. This method provides an effective quality control mechanism for evaluating the DVHs of the OARs. Adoption of such a method will advance the quality of current IMRT planning, providing better treatment plan consistency.

  11. Fiber optic spanner

    Science.gov (United States)

    Black, Bryan; Mohanty, Samarendra

    2011-10-01

    Rotation is a fundamental function in nano/biotechnology and is being useful in a host of applications such as pumping of fluid flow in microfluidic channels for transport of micro/nano samples. Further, controlled rotation of single cell or microscopic object is useful for tomographic imaging. Though conventional microscope objective based laser spanners (based on transfer of spin or orbital angular momentum) have been used in the past, they are limited by the short working distance of the microscope objective. Here, we demonstrate development of a fiber optic spanner for rotation of microscopic objects using single-mode fiber optics. Fiber-optic trapping and simultaneous rotation of pin-wheel structure around axis perpendicular to fiber-optic axis was achieved using the fiber optic spanner. By adjusting the laser beam power, rotation speed of the trapped object and thus the microfluidic flow could be controlled. Since this method does not require special optical or structural properties of the sample to be rotated, three-dimensional rotation of a spherical cell could also be controlled. Further, using the fiber optic spanner, array of red blood cells could be assembled and actuated to generate vortex motion. Fiber optical trapping and spinning will enable physical and spectroscopic analysis of microscopic objects in solution and also find potential applications in lab- on-a-chip devices.

  12. An Accurate, Flexible and Small Optical Fiber Sensor: A Novel Technological Breakthrough for Real-Time Analysis of Dynamic Blood Flow Data In Vivo

    OpenAIRE

    Qiao-ying Yuan; Ling Zhang; Dan Xiao,; Kun Zhao; Chun Lin; Liang-yi Si

    2014-01-01

    Because of the limitations of existing methods and techniques for directly obtaining real-time blood data, no accurate microflow in vivo real-time analysis method exists. To establish a novel technical platform for real-time in vivo detection and to analyze average blood pressure and other blood flow parameters, a small, accurate, flexible, and nontoxic Fabry-Perot fiber sensor was designed. The carotid sheath was implanted through intubation of the rabbit carotid artery (n = 8), and the bloo...

  13. Retinal flow cytometer

    OpenAIRE

    Alt, C.; Veilleux, I.; H. Lee; Pitsillides, C. M.; Côté, D.; Lin, C.P.

    2007-01-01

    The in vivo flow cytometer is an instrument capable of continuous, real-time monitoring of fluorescently labeled cells in the circulation without the need to draw blood samples. However, the original system probes a single vessel in the mouse ear; the small sample volume limits the sensitivity of the technique. We describe an in vivo retinal flow cytometer that simultaneously probes five artery–vein pairs in the mouse eye by circularly scanning a small laser spot rapidly around the optic nerv...

  14. An Optical Analog of a Black Holes

    CERN Document Server

    Royston, A; Royston, Andrew; Gass, Richard

    2002-01-01

    Using media with extremely low group velocities one can create an optical analog of a curved space-time. Leonhardt and Piwnicki have proposed that a vortex flow will act as an optical black hole. We show that although the Leonhardt - Piwnicki flow has an orbit of no return and an infinite red-shift surface, it is not a true black hole since it lacks a null hypersurface. However a radial flow will produce a true optical black hole that has a Hawking temperature and obeys the first law of black hole mechanics. By combining the Leonhardt - Piwnicki flow with a radial flow we obtain the analog of the Kerr black hole.

  15. Rapid isoelectric point determination in a miniaturized preparative separation using jet-dispensed optical pH sensors and micro free-flow electrophoresis.

    Science.gov (United States)

    Herzog, Christin; Beckert, Erik; Nagl, Stefan

    2014-10-01

    Herein, the fabrication, characterization, calibration, and application of integrated microfluidic platforms for fast isoelectric point (pI) determinations via free-flow electrophoresis with integrated inkjet-printed fluorescent pH sensor microstructures are presented. These devices allow one to determine the pI of a biomolecule from a sample mixture with moderately good precision and without addition of markers in typically less than 10 s total separation and analysis time. Polyhydroxyethyl methacrylate (pHEMA) hydrogels were covalently coupled with fluorescein and hydroxypyrene trisulfonic acid (HPTS)-based pH probes. These were piezoelectrically jet-dispensed onto acrylate-modified glass as pH sensor microarrays with a diameter of 300-600 μm and thicknesses of 0.4-2.4 μm with high spatial accuracy. Microchip fabrication and integration of these pH sensor arrays was realized by multistep liquid-phase photolithography from oligoethylene glycol precursors resulting in glass-based microfluidic free-flow isoelectric focusing (μFFIEF) chips with integrated pH observation capabilities. The microchips were characterized with regard to pH sensitivity, response times, photo-, and flow stability. Depending on the sensor matrix, they allowed IEF within a pH range of roughly 5.5-10.5 with good sensitivity and fast response times. These microchips were used for FFIEF of small molecule markers and several protein mixtures with simultaneous monitoring of local pH. This allowed the determination of their pI via multispectral imaging of protein and pH sensor fluorescence without addition of external markers. Obtained pI's were generally in good agreement with known data, demonstrating the applicability of the method for pI determination in micropreparative procedures within a time frame of a few seconds only.

  16. Multi-reverse flow injection analysis integrated with multi-optical sensor for simultaneous determination of Mn(II), Fe(II), Cu(II) and Fe(III) in natural waters.

    Science.gov (United States)

    Youngvises, Napaporn; Suwannasaroj, Kittigan; Jakmunee, Jaroon; AlSuhaimi, Awadh

    2017-05-01

    Multi-reverse flow injection analysis (Mr-FIA) integrated with multi-optical sensor was developed and optimized for the simultaneous determination of multi ions; Mn(II), Fe(II), Cu(II) and Fe(III) in water samples. The sample/standard solutions were propelled making use of a four channels peristaltic pump whereas 4 colorimetric reagents specific for the metal ions were separately injected in sample streams using multi-syringe pump. The color zones that formed in the individual mixing coils were then streamed into multi-channels spectrometer, which comprised of four flows through cell and four pairs of light emitting diode and photodiode, whereby signals were measured concurrently. The linearity range (along with detection limit, µgL(-1)) was 0.050-3.0(16), 0.30-2.0 (11), 0.050-1.0(12) and 0.10-1.0(50)mgL(-1), for Mn(II), Fe(II), Cu(II) and Fe(III), respectively. In the interim, the correlation coefficients were 0.9924-0.9942. The percentages relative standard deviation was less than 3. The proposed system was applied successfully to determine targeted metal ions simultaneously in natural water with high sample throughput and low reagent consumption, thus it satisfies the criteria of Green Analytical Chemistry (GAC) and its goals.

  17. Investigations on the use of pneumatic cross-flow nebulizers with dual solution loading including the correction of matrix effects in elemental determinations by inductively coupled plasma optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Mathieu [Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg (Germany); Broekaert, Jose A.C. [Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg (Germany)], E-mail: jose.broekaert@chemie.uni-hamburg.de

    2007-02-15

    The use of a so-called trihedral and a T-shaped cross-flow pneumatic nebulizer with dual solution loading for inductively coupled plasma optical emission spectrometry has been studied. By these devices analyte clouds from two solutions can be mixed during the aerosol generation step. For both nebulizers the correction of matrix effects using internal standardization and standard addition calibration in an on-line way was investigated and compared to elemental determinations using a conventional cross-flow nebulizer and calibration with synthetic standard solutions without matrix matching. A significant improvement of accuracy, both for calibration with internal standardization and standard addition, was obtained in the case of four synthetic solutions containing each 40 mmol L{sup -1} Na, K, Rb and Ba as matrix elements and 300 {mu}g L{sup -1} Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb as analytes. Calibration by standard addition in the case of dual solution loading has been shown to be very useful in the determination of elements at minor and trace levels in steel and alumina reference materials. The results of analysis for minor concentrations of Cr, Cu and Ni in steel as well as for Ca, Fe, Ga, Li, Mg, Mn, Na, Si and Zn in alumina powder certified reference materials subsequent to sample dissolution were found to be in good agreement with the certificates. Limits of detection were found to be only slightly above those for a conventional cross-flow nebulizer and a precision better than 3% was realized with both novel nebulizers.

  18. Analysis of metals and phosphorus in biodiesel B100 from different feedstock using a Flow Blurring® multinebulizer in inductively coupled plasma-optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Avila Orozco, Francisco D. [Lab. FIA, Sección Química Analítica, INQUISUR (UNS-CONICET), Universidad Nacional del Sur, Avenida Alem 1253, B8000CPB, Bahía Blanca (Argentina); Kovachev, Nikolay; Aguirre Pastor, Miguel Ángel [Dpto. Química Analítica, Nutrición y Bromatología e Instituto Universitario de Materiales, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, Alicante (Spain); Domini, Claudia E.; Fernández Band, Beatriz S. [Lab. FIA, Sección Química Analítica, INQUISUR (UNS-CONICET), Universidad Nacional del Sur, Avenida Alem 1253, B8000CPB, Bahía Blanca (Argentina); Canals Hernández, Antonio, E-mail: a.canals@ua.es [Dpto. Química Analítica, Nutrición y Bromatología e Instituto Universitario de Materiales, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, Alicante (Spain)

    2014-05-01

    Highlights: • The elemental analysis of biodiesel by the proposed method is simple and fast. • Two-nozzles Flow Blurring® nebulizer allow to reduce the spectral interferences. • Two-nozzles Flow Blurring® nebulizer avoid the formation of carbon deposits. • The analysis may be carried out without any sample pretreatment. Abstract: A simple and fast method for determining the content of Na, K, Ca, Mg, P, and 20 heavy metals in biodiesel samples with inductively coupled plasma optical emission spectrometry (ICP OES) using a two-nozzle Flow Blurring® multinebulizer prototype and on-line internal standard calibration, are proposed. The biodiesel samples were produced from different feedstock such as sunflower, corn, soybean and grape seed oils, via a base catalyst transesterification. The analysis was carried out without any sample pretreatment. The standards and samples were introduced through one of the multinebulizer nozzles, while the aqueous solution containing yttrium as an internal standard was introduced through the second nozzle. Thus, the spectral interferences were compensated and the formation of carbon deposits on the ICP torch was prevented. The determination coefficients (R²) were greater than 0.99 for the studied analytes, in the range 0.21–14.75 mg kg⁻¹. Short-term and long-term precisions were estimated as relative standard deviation. These were acceptable, their values being lower than 10%. The LOQ for major components such as Ca, K, Mg, Na, and P, were within a range between 4.9 ng g⁻¹ for Mg (279.553 nm) and 531.1 ng g⁻¹ for Na (588.995 nm), and for the other 20 minor components they were within a range between 1.1 ng g⁻¹ for Ba (455.403 nm) and 2913.9 ng g⁻¹ for Pb (220.353 nm). Recovery values ranged between 95% and 106%.

  19. Optical processing

    Science.gov (United States)

    Gustafson, S. C.

    1985-12-01

    The technical contributions were as follows: (1) Optical parallel 2-D neighborhood processor and optical processor assessment technique; (2) High accuracy with moderately accurate components and optical fredkin gate architectures; (3) Integrated optical threshold computing, pipelined polynomial processor, and all optical analog/digital converter; (4) Adaptive optical associative memory model with attention; (5) Effectiveness of parallelism and connectivity in optical computers; (6) Optical systolic array processing using an integrated acoustooptic module; (7) Optical threshold elements and networks, holographic threshold processors, adaptive matched spatial filtering, and coherence theory in optical computing; (8) Time-varying optical processing for sub-pixel targets, optical Kalman filtering, and adaptive matched filtering; (9) Optical degrees of freedom, ultra short optical pulses, number representations, content-addressable-memory processors, and integrated optical Givens rotation devices; (10) Optical J-K flip flop analysis and interfacing for optical computers; (11) Matrix multiplication algorithms and limits of incoherent optical computers; (12) Architecture for machine vision with sensor fusion, pattern recognition functions, and neural net implementations; (13) Optical computing algorithms, architectures, and components; and (14) Dynamic optical interconnections, advantages and architectures.

  20. Line-scanning particle image velocimetry: an optical approach for quantifying a wide range of blood flow speeds in live animals.

    Directory of Open Access Journals (Sweden)

    Tyson N Kim

    Full Text Available BACKGROUND: The ability to measure blood velocities is critical for studying vascular development, physiology, and pathology. A key challenge is to quantify a wide range of blood velocities in vessels deep within living specimens with concurrent diffraction-limited resolution imaging of vascular cells. Two-photon laser scanning microscopy (TPLSM has shown tremendous promise in analyzing blood velocities hundreds of micrometers deep in animals with cellular resolution. However, current analysis of TPLSM-based data is limited to the lower range of blood velocities and is not adequate to study faster velocities in many normal or disease conditions. METHODOLOGY/PRINCIPAL FINDINGS: We developed line-scanning particle image velocimetry (LS-PIV, which used TPLSM data to quantify peak blood velocities up to 84 mm/s in live mice harboring brain arteriovenous malformation, a disease characterized by high flow. With this method, we were able to accurately detect the elevated blood velocities and exaggerated pulsatility along the abnormal vascular network in these animals. LS-PIV robustly analyzed noisy data from vessels as deep as 850 µm below the brain surface. In addition to analyzing in vivo data, we validated the accuracy of LS-PIV up to 800 mm/s using simulations with known velocity and noise parameters. CONCLUSIONS/SIGNIFICANCE: To our knowledge, these blood velocity measurements are the fastest recorded with TPLSM. Partnered with transgenic mice carrying cell-specific fluorescent reporters, LS-PIV will also enable the direct in vivo correlation of cellular, biochemical, and hemodynamic parameters in high flow vascular development and diseases such as atherogenesis, arteriogenesis, and vascular anomalies.