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Sökning: WFRF:(Kuang Yubin)

  • Resultat 1-10 av 29
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1.
  • Ask, Erik, et al. (författare)
  • A Unifying Approach to Minimal Problems in Collinear and Planar TDOA Sensor Network Self-Calibration
  • 2014
  • Ingår i: European Signal Processing Conference. - 2219-5491.
  • Konferensbidrag (refereegranskat)abstract
    • This work presents a study of sensor network calibration from time-difference-of-arrival (TDOA) measurements for cases when the dimensions spanned by the receivers and the transmitters differ. This could for example be if receivers are restricted to a line or plane or if the transmitting objects are moving linearly in space. Such calibration arises in several applications such as calibration of (acoustic or ultrasound) microphone arrays, and radio antenna networks. We propose a non-iterative algorithm based on recent stratified approaches: (i) rank constraints on modified measurement matrix, (ii) factorization techniques that determine transmitters and receivers up to unknown affine transformation and (iii) determining the affine stratification using remaining non-linear constraints. This results in a unified approach to solve almost all minimal problems. Such algorithms are important components for systems for self-localization. Experiments are shown both for simulated and real data with promising results.
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2.
  • Ask, Erik, et al. (författare)
  • Exploiting p-Fold Symmetries for Faster Polynomial Equation Solving
  • 2012
  • Ingår i: 21st International Conference on Pattern Recognition (ICPR 2012), Proceedings of. - 9784990644116 ; , s. 3232-3235
  • Konferensbidrag (refereegranskat)abstract
    • Numerous geometric problems in computer vision in- volve the solution of systems of polynomial equations. This is true for problems with minimal information, but also for finding stationary points for overdetermined problems. The state-of-the-art is based on the use of numerical linear algebra on the large but sparse co- efficient matrix that represents the expanded original equation set. In this paper we present two simplifica- tions that can be used (i) if the zero vector is one of the solutions or (ii) if the equations display certain p- fold symmetries. We evaluate the simplifications on a few example problems and demonstrate that significant speed increases are possible without loosing accuracy.
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3.
  • Beal, Jacob, et al. (författare)
  • Robust estimation of bacterial cell count from optical density
  • 2020
  • Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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4.
  • Burgess, Simon, et al. (författare)
  • Minimal Solvers for Unsynchronized TDOA Sensor Network Calibration
  • 2014
  • Ingår i: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783642453465 ; , s. 95-110
  • Konferensbidrag (refereegranskat)abstract
    • Calibration of network nodes using only time differences of arrival (TDOA) measurements opens up for interesting applications in wireless ad-hoc sensor networks, e.g. finding the positions of cell phones by only ambient sounds or radio. We present two novel approaches for the problem of self-calibration of network nodes using only TDOA when both receivers and transmitters are unsynchronized. We consider the previously unsolved minimum problem of far field localization in three dimensions, which is to locate four receivers by the signals of nine unknown transmitters, for which we assume that they originate from far away. The first approach, the Ellipsoid TDOA method, is a geometric representation based on the fact that the time differences between four receivers characterize an ellipsoid. We calculate by linear least-squares regression the ellipsoid from the observed measurements of nine or more transmitters, by which the constellation of receivers is characterized. In the second approach we propose using linear algebra techniques on the matrix of unsynchronized TDOA measurements, enabling us to solve a set of linear equations for a parametrization of the unknowns. This approach is extended to more than four receivers and nine transmitters in a straightforward manner. In extensive experiments we evaluate and compare both approaches and analyze specific failure modes of the algorithms. Here, we demonstrate that the algorithms are robust to moderate Gaussian measurement noise and that the far field assumption is reasonable if the distance between transmitters and receivers is at least four times the distance between the receivers. In an indoor experiment using sound we reconstruct the microphone positions up to a mean error of 5 cm.
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5.
  • Burgess, Simon, et al. (författare)
  • Node Localization in Unsynchronized Time of Arrival Sensor Networks
  • 2012
  • Ingår i: 21st International Conference on Pattern Recognition (ICPR 2012), Proceedings of. - 9784990644116 ; , s. 2042-2046
  • Konferensbidrag (refereegranskat)abstract
    • We present a method for solving the previously unstudied problem of localizing a set of receivers and directions from transmitters placed far from the receivers, measuring unsynchronized time of arrival data. The same problem is present in node localization of microphone and antenna arrays. The solution algorithm using 5 receivers and 9 transmitters is extended to the overdetermined case in a straightforward manner. Degenerate cases are shown to be when i) the measurement matrix has rank 4 or less or ii) the directions from the transmitters to the receivers lie on an intersection between the unit sphere and another quadric surface. In simulated experiments we explore how sensitive the solution is with respect to different degrees of far field approximations of the transmitters and with respect to noise in the data. Using real data we get a reconstruction of the receivers with a relative error of 14%.
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6.
  • Burgess, Simon, et al. (författare)
  • Pose Estimation from Minimal Dual-Receiver Configurations
  • 2012
  • Ingår i: 21st International Conference on Pattern Recognition (ICPR 2012), Proceedings of. - 9784990644116 ; , s. 2553-2556
  • Konferensbidrag (refereegranskat)abstract
    • Using multiple receivers (microphones or antennas) in a rigid configuration, such as on a smartphone, it is possible to measure time difference of arrival to the receivers. This in turn can be used to determine the direction to the transmissions, if there are at least three receivers. When using two receivers it can be used to determine the angle to the transmissions relative to the line through the two receivers. In this paper we study three minimal problems for pose using such data: (i) determine position and orientation using five transmissions, (ii) determine position and orientation using four transmissions and known ’down’ direction and (iii) determine position using three transmissions and known orientation. Numerically stable solvers are implemented. An experimental validation of the solvers are performed on simulated data
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7.
  • Burgess, Simon, et al. (författare)
  • TOA Sensor Network Calibration for Receiver and Transmitter Spaces with Difference in Dimension
  • 2013
  • Ingår i: 21st European Signal Processing Conference (EUSIPCO 2013).
  • Konferensbidrag (refereegranskat)abstract
    • We study and solve the previously unstudied problem of finding both sender and receiver positions from time of arrival (TOA) measurements when there is a difference in dimensionality between the affine subspaces spanned by receivers and senders. Anchor-free TOA network calibration has uses both in sound, radio and radio strength applications. Using linear techniques and requiring only a minimal number of receivers and senders, an algorithm is constructed for general dimension p for the lower dimensional subspace. Degenerate cases are determined and partially characterized as when receivers or senders inhabits a lower dimensional affine subspace than was given as input. The algorithm is further extended to the overdetermined case in a straightforward manner. Simulated experiments show good accuracy for the minimal solver and good performance under noisy measurements. An indoor environment experiment using microphones and speakers gives a RMSE of 2.35cm on receiver and sender positions compared to computer vision reconstruction.
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8.
  • Burgess, Simon, et al. (författare)
  • TOA sensor network self-calibration for receiver and transmitter spaces with difference in dimension
  • 2015
  • Ingår i: Signal Processing. - : Elsevier BV. - 0165-1684. ; 107:Online 11 June 2014, s. 33-42
  • Tidskriftsartikel (refereegranskat)abstract
    • We study and solve the previously unstudied problem of finding both transmitter and receiver positions using only time of arrival (TOA) measurements when there is a difference in dimensionality between the affine subspaces spanned by receivers and transmitters. Anchor-free TOA network calibration has uses both in radio, radio strength and sound applications, such as calibrating ad hoc microphone arrays. Using linear techniques and requiring only minimal number of receivers and transmitters, an algorithm is constructed for general dimension p for the lower dimensional subspace. Degenerate cases are determined and partially characterized as when receivers or transmitters inhabit a lower dimensional affine subspace than was given as input. The algorithm is further extended to overdetermined cases in a straightforward manner. Utilizing the minimal solver, an algorithm using the Random Sample Consensus (RANSAC) paradigm has been constructed to simultaneously solve the calibration problem and remove severe outliers, a common problem in TOA applications. Simulated experiments show good performance for the minimal solver and the RANSAC-like algorithm under noisy measurements. Two indoor environment experiments using microphones and speakers give a RMSE of 2.35 cm and 3.95 cm on receiver and transmitter positions compared to computer vision reconstructions.
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9.
  • Jiang, Fangyuan, et al. (författare)
  • A Minimal Solution to Relative Pose with Unknown Focal Length and Radial Distortion
  • 2015
  • Ingår i: [Host publication title missing]. - Cham : Springer International Publishing. - 0302-9743 .- 1611-3349. ; 9004, s. 443-456
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we study the minimal problem of estimating the essential matrix between two cameras with constant but unknown focal length and radial distortion. This problem is of both theoretical and practical interest and it has not been solved previously. We have derived a fast and stable polynomial solver based on Gr{\"o}bner basis method. This solver enables simultaneous auto-calibration of focal length and radial distortion for cameras. For experiments, the numerical stability of the solver is demonstrated on synthetic data. We also evaluate on real images using either RANSAC or kernel voting. Compared with the standard minimal solver, which does not model the radial distortion, our proposed solver both finds a larger set of geometrically correct correspondences on distorted images and gives an accurate estimate of the radial distortion and focal length.
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10.
  • Jiang, Fangyuan, et al. (författare)
  • Time Delay Estimation for TDOA Self-Calibration using Truncated Nuclear Norm Regularization
  • 2013
  • Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2013 IEEE International Conference on. - 1520-6149. ; , s. 3885-3889
  • Konferensbidrag (refereegranskat)abstract
    • Measurements with unknown time delays are common in different applications such as microphone array, radio antenna array calibration, where the sources (e.g. sounds) are transmitted in unknown time instants. In this paper, we present a method for estimating unknown time delays from Time-Difference-of-Arrival (TDOA) measurements. We propose a novel rank constraint on a matrix depending on the measurements and the unknown time delays. The time delays are recovered by solving a truncated nuclear norm minimization problem using alternating direction method of multipliers (ADMM). We show in synthetic experiments that the proposed method recovers the time delays with good accuracy for noisy and missing data.
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  • Resultat 1-10 av 29

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