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1
Corcino, Cristina B., and Roberto B. Corcino. "An Asymptotic Formula for r-Bell Numbers with Real Arguments." ISRN Discrete Mathematics 2013 (February 13, 2013): 1–7. http://dx.doi.org/10.1155/2013/274697.
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The r-Bell numbers are generalized using the concept of the Hankel contour. Some properties parallel to those of the ordinary Bell numbers are established. Moreover, an asymptotic approximation for r-Bell numbers with real arguments is obtained.
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Pak, Ronald Y. S., and Xiaoyong Bai. "Analytic resolution of time-domain half-space Green's functions for internal loads by a displacement potential-Laplace-Hankel-Cagniard transform method." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2235 (March 2020): 20190610. http://dx.doi.org/10.1098/rspa.2019.0610.
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A refined yet compact analytical formulation is presented for the time-domain elastodynamic response of a three-dimensional half-space subject to an arbitrary internal or surface force distribution. By integrating Laplace and Hankel transforms into a method of displacement potentials and Cagniard's inversion concept, it is shown that the solution can be derived in a straightforward manner for the generalized classical wave propagation problem. For the canonical case of a buried point load with a step time function, the response is proved to be naturally reducible with the aid of a parametrized Bessel function integral representation to six wave-group integrals on finite contours in the complex plane that stay away from all branch points and the Rayleigh pole except possibly at the starting point of the contours. On the latter occasions, the possible singularities of the integrals can be rigorously extracted by an extended method of asymptotic decomposition, rendering the residual numerical computation a simple exercise. With the new solution format, the arrival time of each wave group is derivable by simple criteria on the contour. Typical results for the time-domain response for an internal point force as well as the degenerate case of a surface point source are included for comparison and illustrations.
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Boyadzhiev, Khristo N. "Evaluation of series with Hurwitz and Lerch zeta function coefficients by using Hankel contour integrals." Applied Mathematics and Computation 186, no. 2 (March 2007): 1559–71. http://dx.doi.org/10.1016/j.amc.2006.08.061.
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Fokas, A. S., and M. L. Glasser. "The Laplace equation in the exterior of the Hankel contour and novel identities for hypergeometric functions." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, no. 2157 (September 8, 2013): 20130081. http://dx.doi.org/10.1098/rspa.2013.0081.
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By using conformal mappings, it is possible to express the solution of certain boundary-value problems for the Laplace equation in terms of a single integral involving the given boundary data. We show that such explicit formulae can be used to obtain novel identity for special functions. A convenient tool for deriving this type of identity is the so-called global relation , which has appeared recently in a wide range of boundary-value problems. As a concrete application, we analyse the Neumann boundary-value problem for the Laplace equation in the exterior of the Hankel contour, which appears in the definition of both the gamma and the Riemann zeta functions. By using the explicit solution of this problem, we derive a number of novel identities involving the hypergeometric function. Also, we point out an interesting connection between the solution of the above Neumann boundary-value problem for a particular set of Neumann data and the Riemann hypothesis.
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Tsai, Y. M. "Forced Vibratory Motion of a Circular Disk on an Infinite Transversely Isotropic Medium." Journal of Energy Resources Technology 111, no. 1 (March 1, 1989): 50–54. http://dx.doi.org/10.1115/1.3231401.
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The forced vertical vibratory motion of a rigid body with a circular base on the surface of a transversely isotropic material is investigated by using the method of Hankel transform. The total dynamic contact force is obtained through a complete contour integration in terms of the Rayleigh surface waves. The real-valued displacement functions are expressed in terms of the frequency factor and the anisotropic material constants. The resonant amplitudes of vibration are shown to depend significantly on the anisotropic material constants, the mass ratio, and the vibration frequency.
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Tsai, Y. M. "Dynamic Response to Normal Stresses in a Transversely Isotropic Material Containing an External Circular Crack." Journal of Engineering Materials and Technology 114, no. 2 (April 1, 1992): 208–12. http://dx.doi.org/10.1115/1.2904163.
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The dynamic response of an external circular crack to a harmonic longitudinal wave in a transversely isotropic material is investigated using the techniques of Hankel transform. The wave impinges normally onto the crack surfaces. The inversion integral is evaluated and simplified through a complete contour integration. An exact expression for the dynamic stress intensity factor is obtained in terms of the wave frequency and the anisotropic material constants. The maximum value of the normalized dynamic stress-intensity factor is shown to occur at different wave frequencies for different sample composite and metallic materials. The dynamic effect on the crack surface displacement is also shown to be a function of the wave frequency and the material anisotropy.
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Dainty, Anton M., and David B. Harris. "Phase velocity estimation of diffusely scattered waves." Bulletin of the Seismological Society of America 79, no. 4 (August 1, 1989): 1231–50. http://dx.doi.org/10.1785/bssa0790041231.
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Abstract Two methods are investigated for estimating the phase velocity of diffusely scattered seismic waves simultaneously arriving from different azimuths and recorded by a two-dimensional array of seismometers. The Hankel spectrum is the average of the frequency-wavenumber (FK) spectrum over all azimuths, while the wavenumber spectrum is derived by integrating the FK spectrum around a contour of constant phase velocity, i.e., a circle centered on the origin in the wavenumber plane. If the conventional estimate of the FK spectrum using the covariance matrix of the seismometer signals is integrated, a closed form for both the Hankel spectrum and the wavenumber spectrum may be found; the two spectra are very similar, the wavenumber spectrum being equal to the Hankel spectrum times the wavenumber. In spite of this similarity, however, we find that the two formulations have significantly different behavior for small wavenumbers, i.e., high phase velocities. In both cases there is a highest (true) velocity that can be estimated from the spectral maximum for a given array aperture (“velocity cut-off”). The Hankel spectrum estimates too high a velocity; for true wavenumbers below a certain limit, infinite velocity is estimated. The wavenumber spectrum, on the other hand, estimates too low a velocity, and there is an upper limit on the estimated velocity. An example illustrating these difficulties for the two methods is given for teleseismic P coda of an event recorded at the NORESS array in southern Norway: in spite of the problems, the analysis is able to demonstrate that the coda consists of two components; a coherent P-wave component with a high phase velocity and a diffuse S-wave component of low phase velocity. The cut-off and bias problem are investigated by numerical simulation for the NORESS array using azimuthal averaging and synthetic signals. The results confirm and quantify the cut-off problem at low wavenumbers and indicate that wavenumbers estimated from the Hankel and wavenumber spectra maxima bracket the true wavenumber, with the Hankel spectrum estimate being low (phase velocity too high) and the wavenumber spectrum estimate high. The bias of both methods decreases with increasing wavenumber (decreasing phase velocity) and they are both asymptotically unbiased. The wavenumber spectrum has a superior performance at low wavenumbers (high phase velocity), but the Hankel spectrum gives superior results at high wavenumbers (low phase velocity). The product of the linear wavenumber (= 1/wavelength) and the array aperture define “high” and “low” wavenumbers; for low wavenumbers, the product is 1 or less. In an Appendix, we find absolute lower bounds on the cut-offs analytically. The problems could be mitigated by using high resolution methods.
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Schmidt, Maxie D. "A Short Note on Integral Transformations and Conversion Formulas for Sequence Generating Functions." Axioms 8, no. 2 (May 19, 2019): 62. http://dx.doi.org/10.3390/axioms8020062.
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The purpose of this note is to provide an expository introduction to some more curious integral formulas and transformations involving generating functions. We seek to generalize these results and integral representations which effectively provide a mechanism for converting between a sequence’s ordinary and exponential generating function (OGF and EGF, respectively) and vice versa. The Laplace transform provides an integral formula for the EGF-to-OGF transformation, where the reverse OGF-to-EGF operation requires more careful integration techniques. We prove two variants of the OGF-to-EGF transformation integrals from the Hankel loop contour for the reciprocal gamma function and from Fourier series expansions of integral representations for the Hadamard product of two generating functions, respectively. We also suggest several generalizations of these integral formulas and provide new examples along the way.
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Nickelson, Liudmila, Raimondas Pomarnacki, Tomyslav Sledevič, and Darius Plonis. "Method of Singular Integral Equations for Analysis of Strip Structures and Experimental Confirmation." Mathematics 9, no. 2 (January 11, 2021): 140. http://dx.doi.org/10.3390/math9020140.
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This paper presents a rigorous solution of the Helmholtz equation for regular waveguide structures with the finite sizes of all cross-section elements that may have an arbitrary shape. The solution is based on the theory of Singular Integral Equations (SIE). The SIE method proposed here is used to find a solution to differential equations with a point source. This fundamental solution of the equations is then applied in an integral representation of the general solution for our boundary problem. The integral representation always satisfies the differential equations derived from the Maxwell’s ones and has unknown functions μe and μh that are determined by the implementation of appropriate boundary conditions. The waveguide structures under consideration may contain homogeneous isotropic materials such as dielectrics, semiconductors, metals, and so forth. The proposed algorithm based on the SIE method also allows us to compute waveguide structures containing materials with high losses. The proposed solution allows us to satisfy all boundary conditions on the contour separating materials with different constitutive parameters and the condition at infinity for open structures as well as the wave equation. In our solution, the longitudinal components of the electric and magnetic fields are expressed in the integral form with the kernel consisting of an unknown function μe or μh and the Hankel function of the second kind. It is important to note that the above-mentioned integral representation is transformed into the Cauchy type integrals with the density function μe or μh at certain singular points of the contour of integration. The properties and values of these integrals are known under certain conditions. Contours that limit different materials of waveguide elements are divided into small segments. The number of segments can determine the accuracy of the solution of a problem. We assume for simplicity that the unknown functions μe and μh, which we are looking for, are located in the middle of each segment. After writing down the boundary conditions for the central point of every segment of all contours, we receive a well-conditioned algebraic system of linear equations, by solving which we will define functions μe and μh that correspond to these central points. Knowing the densities μe, μh, it is easy to calculate the dispersion characteristics of the structure as well as the electromagnetic (EM) field distributions inside and outside the structure. The comparison of our calculations by the SIE method with experimental data is also presented in this paper.
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Nickelson, Liudmila, Raimondas Pomarnacki, Tomyslav Sledevič, and Darius Plonis. "Method of Singular Integral Equations for Analysis of Strip Structures and Experimental Confirmation." Mathematics 9, no. 2 (January 11, 2021): 140. http://dx.doi.org/10.3390/math9020140.
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This paper presents a rigorous solution of the Helmholtz equation for regular waveguide structures with the finite sizes of all cross-section elements that may have an arbitrary shape. The solution is based on the theory of Singular Integral Equations (SIE). The SIE method proposed here is used to find a solution to differential equations with a point source. This fundamental solution of the equations is then applied in an integral representation of the general solution for our boundary problem. The integral representation always satisfies the differential equations derived from the Maxwell’s ones and has unknown functions μe and μh that are determined by the implementation of appropriate boundary conditions. The waveguide structures under consideration may contain homogeneous isotropic materials such as dielectrics, semiconductors, metals, and so forth. The proposed algorithm based on the SIE method also allows us to compute waveguide structures containing materials with high losses. The proposed solution allows us to satisfy all boundary conditions on the contour separating materials with different constitutive parameters and the condition at infinity for open structures as well as the wave equation. In our solution, the longitudinal components of the electric and magnetic fields are expressed in the integral form with the kernel consisting of an unknown function μe or μh and the Hankel function of the second kind. It is important to note that the above-mentioned integral representation is transformed into the Cauchy type integrals with the density function μe or μh at certain singular points of the contour of integration. The properties and values of these integrals are known under certain conditions. Contours that limit different materials of waveguide elements are divided into small segments. The number of segments can determine the accuracy of the solution of a problem. We assume for simplicity that the unknown functions μe and μh, which we are looking for, are located in the middle of each segment. After writing down the boundary conditions for the central point of every segment of all contours, we receive a well-conditioned algebraic system of linear equations, by solving which we will define functions μe and μh that correspond to these central points. Knowing the densities μe, μh, it is easy to calculate the dispersion characteristics of the structure as well as the electromagnetic (EM) field distributions inside and outside the structure. The comparison of our calculations by the SIE method with experimental data is also presented in this paper.
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Zhao, Rongchang, Min Wu, Xiyao Liu, Beiji Zou, and Fangfang Li. "Orientation Histogram-Based Center-Surround Interaction: An Integration Approach for Contour Detection." Neural Computation 29, no. 1 (January 2017): 171–93. http://dx.doi.org/10.1162/neco_a_00911.
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Contour is a critical feature for image description and object recognition in many computer vision tasks. However, detection of object contour remains a challenging problem because of disturbances from texture edges. This letter proposes a scheme to handle texture edges by implementing contour integration. The proposed scheme integrates structural segments into contours while inhibiting texture edges with the help of the orientation histogram-based center-surround interaction model. In the model, local edges within surroundings exert a modulatory effect on central contour cues based on the co-occurrence statistics of local edges described by the divergence of orientation histograms in the local region. We evaluate the proposed scheme on two well-known challenging boundary detection data sets (RuG and BSDS500). The experiments demonstrate that our scheme achieves a high [Formula: see text]-measure of up to 0.74. Results show that our scheme achieves integrating accurate contour while eliminating most of texture edges, a novel approach to long-range feature analysis.
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Zhou, Li Fen, and Chang Xu Cai. "An Improved Image Segmentation Active Contour Model." Applied Mechanics and Materials 513-517 (February 2014): 3463–67. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.3463.
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The Chan-Vese (C-V) active contour model has low computational complexity, initialization and insensitive to noise advantagesand utilizes global region information of images, so it is difficult to handle images with intensity inhomogeneity. The Local binary fitting (LBF) model based on local region information has its certain advantages in mages segmentation of weak boundary or uneven greay.but , the segmentation results are very sensitive to the initial contours, In order to address this problem, this paper proposes a new active contour model with a partial differential equation, which integrates both global and local region information. Experimental results show that it has a distinctive advantage over C-V model for images with intensity inhomogeneity, and it is more efficient than LBF.
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Flajolet, Philippe, and Helmut Prodinger. "On Stirling Numbers for Complex Arguments and Hankel Contours." SIAM Journal on Discrete Mathematics 12, no. 2 (January 1999): 155–59. http://dx.doi.org/10.1137/s0895480198332594.
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Abdelsamea, Mohammed M., Giorgio Gnecco, Mohamed Medhat Gaber, and Eyad Elyan. "On the Relationship between Variational Level Set-Based and SOM-Based Active Contours." Computational Intelligence and Neuroscience 2015 (2015): 1–19. http://dx.doi.org/10.1155/2015/109029.
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Most Active Contour Models (ACMs) deal with the image segmentation problem as a functional optimization problem, as they work on dividing an image into several regions by optimizing a suitable functional. Among ACMs, variational level set methods have been used to build an active contour with the aim of modeling arbitrarily complex shapes. Moreover, they can handle also topological changes of the contours. Self-Organizing Maps (SOMs) have attracted the attention of many computer vision scientists, particularly in modeling an active contour based on the idea of utilizing the prototypes (weights) of a SOM to control the evolution of the contour. SOM-based models have been proposed in general with the aim of exploiting the specific ability of SOMs to learn the edge-map information via their topology preservation property and overcoming some drawbacks of other ACMs, such as trapping into local minima of the image energy functional to be minimized in such models. In this survey, we illustrate the main concepts of variational level set-based ACMs, SOM-based ACMs, and their relationship and review in a comprehensive fashion the development of their state-of-the-art models from a machine learning perspective, with a focus on their strengths and weaknesses.
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Chu, I.-Hsien, Minlan Duan, and Shivakumar Sastry. "Contour Guided Dissemination for Networked Embedded Systems." International Journal of Distributed Sensor Networks 5, no. 5 (October 1, 2009): 502–30. http://dx.doi.org/10.1080/15501320701863445.
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Networked Embedded Systems have come to occupy an important role in emerging applications. Nodes in such a system are interconnected by a mesh topology. Despite the availability of multiple shortest paths between pairs of nodes, simulation results revealed that these paths cannot be effectively exploited by spreading the messages over the paths in a uniform method. We define the union of all the shortest paths between a pair of nodes as a contour. We present results that characterize the structure of contours when each node communicates directly with eight immediate neighbors. Heuristic rules that effectively disseminate messages over the available paths are presented. Simulation results demonstrate that the new method for dissemination ensures that nodes in a contour, which are at the same distance from the source, handle roughly the same number of messages. In the future, such techniques can be extended to general topologies.
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Squeri, Valentina, Alessandra Sciutti, Monica Gori, Lorenzo Masia, Giulio Sandini, and Juergen Konczak. "Two hands, one perception: how bimanual haptic information is combined by the brain." Journal of Neurophysiology 107, no. 2 (January 15, 2012): 544–50. http://dx.doi.org/10.1152/jn.00756.2010.
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Humans routinely use both of their hands to gather information about shape and texture of objects. Yet, the mechanisms of how the brain combines haptic information from the two hands to achieve a unified percept are unclear. This study systematically measured the haptic precision of humans exploring a virtual curved object contour with one or both hands to understand if the brain integrates haptic information from the two hemispheres. Bayesian perception theory predicts that redundant information from both hands should improve haptic estimates. Thus exploring an object with two hands should yield haptic precision that is superior to unimanual exploration. A bimanual robotic manipulandum passively moved the hands of 20 blindfolded, right-handed adult participants along virtual curved contours. Subjects indicated which contour was more “curved” (forced choice) between two stimuli of different curvature. Contours were explored uni- or bimanually at two orientations (toward or away from the body midline). Respective psychophysical discrimination thresholds were computed. First, subjects showed a tendency for one hand to be more sensitive than the other with most of the subjects exhibiting a left-hand bias. Second, bimanual thresholds were mostly within the range of the corresponding unimanual thresholds and were not predicted by a maximum-likelihood estimation (MLE) model. Third, bimanual curvature perception tended to be biased toward the motorically dominant hand, not toward the haptically more sensitive left hand. Two-handed exploration did not necessarily improve haptic sensitivity. We found no evidence that haptic information from both hands is integrated using a MLE mechanism. Rather, results are indicative of a process of “sensory selection”, where information from the dominant right hand is used, although the left, nondominant hand may yield more precise haptic estimates.
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Osawa, Fumiaki, and Kazunori Kano. "Contour Tracking of Soft Sheet Materials Using Local Contour Image Data." International Journal of Automation Technology 6, no. 5 (September 5, 2012): 654–61. http://dx.doi.org/10.20965/ijat.2012.p0654.
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Technologies related to the handling of cloth products still rely on human hands in the apparel industry and in the fields of medicine, welfare, and nursing care; hence, the automation of these technologies is strongly desired. However, the cloth material in question is characteristically non-linear and anisotropic, so it is not easy to predict its dynamic deformation. Therefore, no guidelines for integrated methods of using robots to handle cloth material have been established. In this paper, we propose a method of tracking the contour of a piece of cloth that has curved edges. The aim of the method is to spread soft, flat objects of different shapes, such as clothes. We show contour extraction performed by a camera mounted on a fingertip of a robot hand and operational plan of a manipulator on the basis of the extracted information. The effectiveness of the method is demonstrated by extracting the contour of a piece of patterned cloth, controlling the hand direction and the depth of grasp, and tracking the contour of a piece of cloth with partly curved edges.
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Ward, Daniel. "Asymptotic analysis of the Nörlund and Stirling polynomials." Applicable Analysis and Discrete Mathematics 6, no. 1 (2012): 95–105. http://dx.doi.org/10.2298/aadm120219006w.
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We provide a full asymptotic analysis of the N?rlund polynomials and Stirling polynomials. We give a general asymptotic expansion-to any desired degree of accuracy-when the parameter is not an integer. We use singularity analysis, Hankel contours, and transfer theory. This investigation was motivated by a need for such a complete asymptotic description, with parameter 1/2, during this author's recent solution of Wilf's 3rd (previously) Unsolved Problem.
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Gao, Yuan, Xiaosheng Yu, Chengdong Wu, Wei Zhou, Xiaoliang Lei, and Yaoming Zhuang. "Automatic Optic Disc Segmentation Based on Modified Local Image Fitting Model with Shape Prior Information." Journal of Healthcare Engineering 2019 (March 14, 2019): 1–10. http://dx.doi.org/10.1155/2019/2745183.
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Accurate optic disc (OD) detection is an essential yet vital step for retinal disease diagnosis. In the paper, an approach for segmenting OD boundary without manpower named full-automatic double boundary extraction is designed. There are two main advantages in it. (1) Since the performances and the computational cost produced by iterations of contour evolution of active contour models- (ACM-) based approaches greatly depend on the initialization, this paper proposes an effective and adaptive initial level set contour extraction approach using saliency detection and threshold techniques. (2) In order to handle unreliable information generated by intensity in abnormal retinal images caused by diseases, a modified LIF approach is presented by incorporating the shape prior information into LIF. We test the effectiveness of the proposed approach on a publicly available DIARETDB0 database. Experimental results demonstrate that our approach outperforms well-known approaches in terms of the average overlapping ratio and accuracy rate.
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Barry, Steven, Geoffrey Aldis, and Geoffry Mercer. "Injection of Fluid Into a Layer of Deformable Porous Medium." Applied Mechanics Reviews 48, no. 10 (October 1, 1995): 722–26. http://dx.doi.org/10.1115/1.3005054.
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The flow of fluid from a point source into a layer of deformable porous material is considered. The main applications of this work are to subcutaneous injections and subterranean soil flows. The porous material is assumed to be an isotropic, homogeneous, linearly elastic solid. The governing equations are derived for an axisymmetric geometry using linear poro-elasticity and are applied to the situation of a point source at some height z = z0 with a line sink at a distance r = ρ. These are solved analytically using Hankel transform techniques with the Hankel inversion integrals calculated numerically. Results are given for the pressure contours and the displacement of the solid matrix for a variety of source heights and elastic parameters. These indicate the swelling of the medium and subsequent deformation of the free surface. Results indicate regions where one dimensional models may be applicable.
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Haselsteiner, Andreas F., Rafael Reisenhofer, Jan-Hendrik Ohlendorf, and Klaus-Dieter Thoben. "Design for Extremes: A Contour Method for Defining Requirements Based on Multivariate Extremes." Proceedings of the Design Society: International Conference on Engineering Design 1, no. 1 (July 2019): 1433–42. http://dx.doi.org/10.1017/dsi.2019.149.
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AbstractThe design of various products is driven by requirements that describe extremes. In marine structural design, joint extremes of environmental variables like wave height and wind speed are used to define load cases. Similarly, in ergonomic design minimum and maximum values of anthropometric variables are considered to make sure a product is suitable for a wide range of users. Here, we present a method that supports designers to define requirements using joint extreme values: the requirements contour method. The method is based on structural engineering's environmental contour method and uses a dataset and statistical methods to specify a region in the variable space that must be considered in the design process. That region's enclosure is the requirements contour and holds the joint extremes. After formally describing the method, we give an illustrative example of its usage: we use it to define requirements for the design of an ergonomic handle for a power tool. The requirements contour method is a field-independent approach to design for extremes. In the tradition of design for X, we think that a design project can benefit from applying methods that focus on different 'X's.
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Tamoor, Maria, and Irfan Younas. "Automatic segmentation of medical images using a novel Harris Hawk optimization method and an active contour model." Journal of X-Ray Science and Technology 29, no. 4 (July 27, 2021): 721–39. http://dx.doi.org/10.3233/xst-210879.
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Medical image segmentation is a key step to assist diagnosis of several diseases, and accuracy of a segmentation method is important for further treatments of different diseases. Different medical imaging modalities have different challenges such as intensity inhomogeneity, noise, low contrast, and ill-defined boundaries, which make automated segmentation a difficult task. To handle these issues, we propose a new fully automated method for medical image segmentation, which utilizes the advantages of thresholding and an active contour model. In this study, a Harris Hawks optimizer is applied to determine the optimal thresholding value, which is used to obtain the initial contour for segmentation. The obtained contour is further refined by using a spatially varying Gaussian kernel in the active contour model. The proposed method is then validated using a standard skin dataset (ISBI 2016), which consists of variable-sized lesions and different challenging artifacts, and a standard cardiac magnetic resonance dataset (ACDC, MICCAI 2017) with a wide spectrum of normal hearts, congenital heart diseases, and cardiac dysfunction. Experimental results show that the proposed method can effectively segment the region of interest and produce superior segmentation results for skin (overall Dice Score 0.90) and cardiac dataset (overall Dice Score 0.93), as compared to other state-of-the-art algorithms.
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Wu, Boying, and Yunyun Yang. "Local- and Global-Statistics-Based Active Contour Model for Image Segmentation." Mathematical Problems in Engineering 2012 (2012): 1–16. http://dx.doi.org/10.1155/2012/791958.
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This paper presents a local- and global-statistics-based active contour model for image segmentation by applying the globally convex segmentation method. We first propose a convex energy functional with a local-Gaussian-distribution-fitting term with spatially varying means and variances and an auxiliary global-intensity-fitting term. A weight function that varies dynamically with the location of the image is applied to adjust the weight of the global-intensity-fitting term dynamically. The weighted total variation norm is incorporated into the energy functional to detect boundaries easily. The split Bregman method is then applied to minimize the proposed energy functional more efficiently. Our model has been applied to synthetic and real images with promising results. With the local-Gaussian-distribution-fitting term, our model can also handle some texture images. Comparisons with other models show the advantages of our model.
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Rann, Karen, David Fairbairn, and Ella Southern. "Reconstructing the lost contours of Charles Hutton." Abstracts of the ICA 1 (July 15, 2019): 1–2. http://dx.doi.org/10.5194/ica-abs-1-307-2019.
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<p><strong>Abstract.</strong> This study reports on an historical investigation of map-making practice and achievement from the late 18th century, and attempts to reconstruct the practices and outcomes of an innovative surveying and mapping exercise, using historical data and contemporary geospatial data handling. The episode involves the processing of data captured as part of an extensive project by the then (British) Astronomer Royal, Maskelyne, in the mid 1770s, to measure the gravitational attraction and density of the earth.</p><p>This experiment was conducted on the isolated mountain of Schiehallion in Central Scotland, and resulted in several differing approaches to calculating the mass of the mountain, and determining and interpreting the resultant effect on gravity measurements on its slopes. In order to do this, an accurate determination of “the figure and dimensions of the hill” (Maskelyne, 1775) was required. The survey work was undertaken under Maskelyne’s supervision by his previous assistant, Barrow, and local surveyor, Menzies.</p><p>The data collected included astronomical observations to establish latitudinal positions, lengths of fixed base lines (one to the north of the mountain and one to the south), a standard traverse around the mountain to establish fixed points, and transects/vertical profiles radiating from those points. The land surveying techniques were known and widely used, although at the time having only been recently documented, in the book ‘A Treatise on Mensuration’. This was published in 1770 by Charles Hutton (1737-1823) a Newcastle-born mathematician, and was the first volume on surveying written in English. In 1773 Hutton had moved south to become Professor of Mathematics at the Royal Military Academy, Woolwich, and became known to the Royal Society which asked him to process Maskelyne’s data.</p><p>The original field observations (Figure 1), were published in Hutton’s extensive account of his work (Hutton, 1778), which also explained how he was to calculate the mass of the mountain, dividing the landscape into a set of vertical prisms collectively defining the mountain’s shape. Smallwood (2007) describes how Hutton’s volume calculations, along with rock, geology and gravity information, can help estimate earth density.</p><p>The prisms, arranged as circular sections (some individually coloured in Figure 2 to exemplify), had their heights calculated with reference to the height points within them. Clearly, however, some prisms had no heights associated with them. Hutton devised a method of interpolation of prism height for those which had no height data by creating a surface defined by contours: “I fell upon the following method … by which I was enabled to proceed in the estimation of the altitudes both with much expedition and a considerable degree of accuracy. This method was the connecting together by a faint line all the points which were of the same relative altitude: by so doing, I obtained great number of irregular polygons lying within and at some distance from, one another, and bearing a considerable degree of resemblance to each other: these polygons were the figures of so many level or horizontal sections of the hills, the relative altitudes of all the parts of them being known; and as every base or little space had several of them passing through it, I was thereby able to determine the altitude belonging to each space with much ease and accuracy.”</p><p>Although isolines were long established on some maps, and isobaths (depth curves), in particular, were visible on some hydrographic charts from the early 18th century, Hutton has some claim to be the first to use lines of equal altitude (contours) on land-based maps. Unfortunately, despite describing the method of using a ‘faint line’ to elucidate the contours, no graphical artefact exists: there is no evidence that Hutton, or anyone associated with the gravity project, ever published the contour map of Schiehallion.</p><p>Elsewhere in his account of the data processing (Hutton, 1778), significant doubts are expressed about the accuracy and validity of some of the observations, and there is the possibility that Hutton blocked publication of the contour map because of inaccurate observation or conflicting calculations.</p><p>However, the presentation of the full set of observations should allow for a reconstruction of the missing contour map. Processing and visualisation has already been undertaken manually by Johnson (Figure 3).</p><p>An attempt was also made to use standard land surveying software to handle the field observations to calculate and map the data. The Star*NET package (Microsurvey, 2018) has been applied to the traverse observations, using techniques of least squares to obtain the most precise positioning of the surrounding stations. The LSS package (McCarthy Taylor, 2018) is used to enter the tacheometric detailing observations, and create an accurate digital terrain model based on the observed data from over 240 years ago. The contour lines derived from this model will be compared with current survey data provided by the British Ordnance Survey, and with satellite derived digital elevation datasets. It is hoped that data manipulation can be undertaken to successfully create a contour map which Charles Hutton would have been happy to publish.</p>
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S. A., Karthik, and Manjunath S. S. "Microarray spot partitioning by autonoumsly organising maps thorugh contour model." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 1 (February 1, 2020): 746. http://dx.doi.org/10.11591/ijece.v10i1.pp746-756.
Full textAbstract:
In cDNA microarray image analysis, classification of pixels as forefront area and the area covered by background is very challenging. In microarray experimentation, identifying forefront area of desired spots is nothing but computation of forefront pixels concentration, area covered by spot and shape of the spots. In this piece of writing, an innovative way for spot partitioning of microarray images using autonomously organizing maps (AOM) method through C-V model has been proposed. Concept of neural networks has been incorpated to train and to test microarray spots.In a trained AOM the comprehensive information arising from the prototypes of created neurons are clearly integrated to decide whether to get smaller or get bigger of contour. During the process of optimization, this is done in an iterative manner. Next using C-V model, inside curve area of trained spot is compared with test spot finally curve fitting is done.The presented model can handle spots with variations in terms of shape and quality of the spots and meanwhile it is robust to the noise. From the review of experimental work, presented approach is accurate over the approaches like C-means by fuzzy, Morphology sectionalization.
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TSECHPENAKIS, GABRIEL, NICOLAS TSAPATSOULIS, and STEFANOS KOLLIAS. "PROBABILISTIC BOUNDARY-BASED CONTOUR TRACKING WITH SNAKES IN NATURAL CLUTTERED VIDEO SEQUENCES." International Journal of Image and Graphics 04, no. 03 (July 2004): 469–98. http://dx.doi.org/10.1142/s0219467804001518.
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Moving object detection and tracking in video sequences is a task that emerges in various research fields of video processing, including video analysis and understanding, object-based coding and many related applications, such as content-based retrieval, remote surveillance and object recognition. This work revisits one of the most popular deformable templates for shape modeling and object tracking, the Snakes, and proposes a modified snake model and a probabilistic utilization of it for object tracking. Special attention has been drawn to complex natural (indoor and outdoor) sequences, where temporal clutter, abrupt motion and external lighting changes are crucial for the accuracy of the results, also focusing on the ability of the proposed approach to handle specific HCI problems, such as face and facial feature tracking. A variety of image sequences are used to illustrate the method's capability, providing theoretical explanation as well as experimental verification in specific tracking problems.
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Tseng, Kuo-Kun, Yifan Li, Chih-Yu Hsu, Huang-Nan Huang, Ming Zhao, and Mingyue Ding. "Computer-Assisted System with Multiple Feature Fused Support Vector Machine for Sperm Morphology Diagnosis." BioMed Research International 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/687607.
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Sperm morphology is an important technique in identifying the health of sperms. In this paper we present a new system and novel approaches to classify different kinds of sperm images in order to assess their health. Our approach mainly relies on a one-dimensional feature which is extracted from the sperm’s contour with gray level information. Our approach can handle rotation and scaling of the image. Moreover, it is fused with SVM classification to improve its accuracy. In our evaluation, our method has better performance than the existing approaches to sperm classification.
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Taufiq, Muhammad, and Marjan Uddin. "Numerical Solution of Fractional Order Anomalous Subdiffusion Problems Using Radial Kernels and Transform." Journal of Mathematics 2021 (July 8, 2021): 1–9. http://dx.doi.org/10.1155/2021/9965734.
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By coupling of radial kernels and localized Laplace transform, a numerical scheme for the approximation of time fractional anomalous subdiffusion problems is presented. The fractional order operators are well suited to handle by Laplace transform and radial kernels are also built for high dimensions. The numerical computations of inverse Laplace transform are carried out by contour integration technique. The computation can be done in parallel and no time sensitivity is involved in approximating the time fractional operator as contrary to finite differences. The proposed numerical scheme is stable and accurate.
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Mohebalhojeh, Ali R., and David G. Dritschel. "Assessing the Numerical Accuracy of Complex Spherical Shallow-Water Flows." Monthly Weather Review 135, no. 11 (November 1, 2007): 3876–94. http://dx.doi.org/10.1175/2007mwr2036.1.
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Abstract The representation of nonlinear shallow-water flows poses severe challenges for numerical modeling. The use of contour advection with contour surgery for potential vorticity (PV) within the contour-advective semi-Lagrangian (CASL) algorithm makes it possible to handle near-discontinuous distributions of PV with an accuracy beyond what is accessible to conventional algorithms used in numerical weather and climate prediction. The emergence of complex distributions of the materially conserved quantity PV, in the absence of forcing and dissipation, results from large-scale shearing and deformation and is a common feature of high Reynolds number flows in the atmosphere and oceans away from boundary layers. The near-discontinuous PV in CASL sets a limit on the actual numerical accuracy of the Eulerian, grid-based part of CASL. For the spherical shallow-water equations, the limit is studied by comparing the accuracy of CASL algorithms with second-order-centered, fourth-order-compact, and sixth-order-supercompact finite differencing in latitude in conjunction with a spectral treatment in longitude. The comparison is carried out on an unstable midlatitude jet at order one Rossby number and low Froude number that evolves into complex vortical structures with sharp gradients of PV. Quantitative measures of global conservation of energy and angular momentum, and of imbalance as diagnosed using PV inversion by means of Bolin–Charney balance, indicate that fourth-order differencing attains the highest numerical accuracy achievable for such nonlinear, advectively dominated flows.
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Yang, Xiaojun, and Xiaoliang Jiang. "A Hybrid Active Contour Model based on New Edge-Stop Functions for Image Segmentation." International Journal of Ambient Computing and Intelligence 11, no. 1 (January 2020): 87–98. http://dx.doi.org/10.4018/ijaci.2020010105.
Full textAbstract:
Edge-based active contour methods are popular algorithms for image segmentation, with the purpose to extract the area of interest. However, they may face to boundary leakage and improper segmentation when handle images under weak edges or complex shapes. The extensive edge-stop functions adopt edge information, which cannot apply to guide the evolving curve approaching to target boundaries. To resolve this issue, a novel level set algorithm based on non-local means (NLM) filtering is constructed in this study. Firstly, the images are subjected to non-local means filtering to generate edge map. Secondly, a new edge-stop function constructed from this edge map as well as the fuzzy k-NN classification algorithm is incorporated into the variational model. Our experiments demonstrate that non-local means filtering is able to sharp edges both on medical and natural images. Thus, this analysis seems to be useful for clinical medical diagnosis.
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Hunka, Steve, and Jacqueline Leighton. "Defining Johnson-Neyman Regions of Significance in the Three-Covariate ANCOVA Using Mathematica." Journal of Educational and Behavioral Statistics 22, no. 4 (December 1997): 361–87. http://dx.doi.org/10.3102/10769986022004361.
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The Johnson-Neyman ANCOVA, used when nonhomogeneity of within-group regressions is present, poses special computational and plotting problems when three covariates are used. These problems can be overcome by using (a) an appropriate design and contrast matrix for the general linear model and (b) the Mathematica software system of computation to handle the symbolic and graphical processing requirements. Four-dimensional graphical representation of the polynomials which result are contour plotted in a three-dimensional space in order to define the regions of significance for contrasts. It is also shown that for some values of the covariate orthogonal contrasts are produced.
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Sittiprapaporn, Phakkharawat. "Preattentive detection of auditory memory representations in accumulative drinker." Asian Journal of Medical Sciences 11, no. 1 (January 1, 2020): 85–89. http://dx.doi.org/10.3126/ajms.v11i1.26579.
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Background: Chinese and English listeners did not show the same left-hemisphere (LH) lateralization as Thai listeners when making perceptual judgments of Thai tones. Although the left hemisphere is selectively employed for processing linguistic information irrespectively of acoustic cues or subtype of phonological unit, the right-hemisphere (RH) is employed for prosody-specific cues.
Aims and Objective: As both hemispheres are lateralized for speech and language, the objective of this study is to extend the investigation of how the pre-attentive processing of contour tone changes of Thai monosyllabic words in alcoholic drinkers.
Materials and Methods: Forty healthy right-handed adults participated in this study.
Results: This study found that both rising-to-falling and falling-to-rising tone changes perception elicited Mismatch Negativity (MMN) between 217-264 msec with reference to the standard-stimulus Event-Related Potentials (ERPs). The rising-to-falling and falling-to-rising tone changes elicited a strong MMN for both groups. Source localization was obtained in the Middle Temporal Gyrus (MTG) of the right hemisphere (RH) for both groups.
Conclusion: Automatic detection of changes in contour tones is a useful index of language universal auditory memory traces.
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Li, Xiaobo, and Laust B. Pedersen. "The electromagnetic response of an azimuthally anisotropic half‐space." GEOPHYSICS 56, no. 9 (September 1991): 1462–73. http://dx.doi.org/10.1190/1.1443166.
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Fracture zones are pervasive in crystalline areas. When the earth is seen over a sufficiently large volume fracture zones may be too thin to be individually identified. If they have preferred directions in that volume, the volume can be considered to be an azimuthally anisotropic medium. We have formulated the electromagnetic fields induced by a horizontal electric dipole on the surface of a homogeneous half‐space with azimuthally anisotropic conductivity. The field components are expressed by the two‐dimensional Fourier transform which can be computed by a fast Hankel transform method. The impedance tensor and tipper functions of controlled source tensor magnetotellurics are derived by exciting the dipole source in two different directions. We show the behavior of impedance tensor, tipper functions and their derived quantities: rotational invariants and Parkinson vectors. All transfer functions clearly show anisotropic characteristics. Contours of rotationally invariant apparent resistivities and phases for fixed frequencies are elongated in the direction of maximum conductivity, and Parkinson’s vectors tend to point in the same direction.
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Loring, Beth, and Erin-Anne Lemieux. "User Research Improves Laparoscopic Instruments." Ergonomics in Design: The Quarterly of Human Factors Applications 18, no. 1 (January 2010): 18–23. http://dx.doi.org/10.1518/106480410x12658371678471.
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FEATURE AT A GLANCE: This case study describes the user-centered redesign of a laparoscopic instrument handle for Cardinal Health. A multidisciplinary team designed a new handle that addressed multiple ergonomic shortcomings and enabled surgeons to perform procedures with greater comfort, safety, and efficiency. Improvements included a flexible grip to allow palming or use of finger rings; broad, contoured surfaces that provided comfort and avoided pressure points; a larger rotation knob with ribs to aid grip, especially with wet gloves; and a tapered shape to accommodate a wide range of finger lengths and grip styles.
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Hong, Yu-Jin, Sung Eun Choi, Gi Pyo Nam, Heeseung Choi, Junghyun Cho, and Ig-Jae Kim. "Adaptive 3D Model-Based Facial Expression Synthesis and Pose Frontalization." Sensors 20, no. 9 (May 1, 2020): 2578. http://dx.doi.org/10.3390/s20092578.
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Facial expressions are one of the important non-verbal ways used to understand human emotions during communication. Thus, acquiring and reproducing facial expressions is helpful in analyzing human emotional states. However, owing to complex and subtle facial muscle movements, facial expression modeling from images with face poses is difficult to achieve. To handle this issue, we present a method for acquiring facial expressions from a non-frontal single photograph using a 3D-aided approach. In addition, we propose a contour-fitting method that improves the modeling accuracy by automatically rearranging 3D contour landmarks corresponding to fixed 2D image landmarks. The acquired facial expression input can be parametrically manipulated to create various facial expressions through a blendshape or expression transfer based on the FACS (Facial Action Coding System). To achieve a realistic facial expression synthesis, we propose an exemplar-texture wrinkle synthesis method that extracts and synthesizes appropriate expression wrinkles according to the target expression. To do so, we constructed a wrinkle table of various facial expressions from 400 people. As one of the applications, we proved that the expression-pose synthesis method is suitable for expression-invariant face recognition through a quantitative evaluation, and showed the effectiveness based on a qualitative evaluation. We expect our system to be a benefit to various fields such as face recognition, HCI, and data augmentation for deep learning.
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JIA, SUSU, and YONG HUANG. "Wieseria bicepes sp. nov. (Nematoda: Oxystominidae) from the South China Sea." Zootaxa 4722, no. 4 (January 15, 2020): 389–94. http://dx.doi.org/10.11646/zootaxa.4722.4.8.
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One unrecorded species of free-living marine nematodes from the South China Sea is described as Wieseria bicepes sp. nov. The present species is characterized by three circles of anterior sensilla nearly equal in length; four cephalic setae just behind the outer labial setae; oblong amphideal fovea with double contours and a handle-like protrusion at the base; tail tip bifurcate; spicules slightly curved with proximally cephalated and distally tapered; gubernaculum absent. The species is easily distinguished from the congeneric species by tail with a bifurcate tip and cephalic setae closely adjacent to labial setae.
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Osawa, Fumiaki, Kazunori Kanou, and Yasushi Yamada. "Research on the Form Recognition of Fabric Products: Acquiring the Shapes of Flat, Limp Materials." International Journal of Automation Technology 8, no. 6 (November 5, 2014): 880–87. http://dx.doi.org/10.20965/ijat.2014.p0880.
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In the apparel, medical and welfare, and nursing care industries, working with cloth items is highly dependent on manual work, so many people have hoped that such work could be automated. However, there are still no established ways for robots to handle cloth. In this paper, a method for acquiring developed shapes is proposed for the purpose of form recognition and classification operations of flat, limp materials. Experiments are performed to acquire developed shapes of materials by actively searching for contours of cloth using a sensor embedded in the finger of a robot.
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Gao, Yuan, Xiaosheng Yu, Chengdong Wu, Wei Zhou, Xiaonan Wang, and Yaoming Zhuang. "Accurate Optic Disc and Cup Segmentation from Retinal Images Using a Multi-Feature Based Approach for Glaucoma Assessment." Symmetry 11, no. 10 (October 10, 2019): 1267. http://dx.doi.org/10.3390/sym11101267.
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Accurate optic disc (OD) and optic cup (OC) segmentation play a critical role in automatic glaucoma diagnosis. In this paper, we present an automatic segmentation technique regarding the OD and the OC for glaucoma assessment. First, the robust adaptive approach for initializing the level set is designed to increase the performance of contour evolution. Afterwards, in order to handle the complex OD appearance affected by intensity inhomogeneity, pathological changes, and vessel occlusion, a novel model that integrates ample information of OD with the effective local intensity clustering (LIC) model together is presented. For the OC segmentation, to overcome the segmentation challenge as the OC’s complex anatomy location, a novel preprocessing method based on structure prior information between the OD and the OC is designed to guide contour evolution in an effective region. Then, a novel implicit region based on modified data term using a richer form of local image clustering information at each point of interest gathered over a multiple-channel feature image space is presented, to enhance the robustness of the variations found in and around the OC region. The presented models symmetrically integrate the information at each point in a single-channel image from a multiple-channel feature image space. Thus, these models correlate with the concept of symmetry. The proposed models are tested on the publicly available DRISHTI-GS database and the experimental results demonstrate that the models outperform state-of-the-art methods.
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Yin, Xue Feng, Ting Ting Liang, and Ju Fen Fu. "Study on the Molding Mechanism of Three-Dimensional Non-Woven Bra Cup." Advanced Materials Research 175-176 (January 2011): 837–42. http://dx.doi.org/10.4028/www.scientific.net/amr.175-176.837.
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Three-dimensional non-woven is a new kind of filling material which has unique tridimensional structure and excellent properties. It will be gradually applied in the field of bra cups instead of polyurethane foam. In this paper, three-dimensional non-woven and its matching materials are firstly molded into bra cups using a contour molding machine under different molding conditions. Secondly, the performance of these molded cups is analyzed in detail from the aspect of formability, handle and appearance. The performance of three-dimensional non-woven after molding is analyzed in detail from microstructure. Finally, the molding mechanism of three-dimensional non-woven bra cup has been found by researching the relationship between filling material microstructures and molded cup properties. The study provides the bra industry with a valuable basis for molding production of three-dimensional non-woven bra cups.
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Ponnambalam, Vignesh Raja, Marianne Bakken, Richard J. D. Moore, Jon Glenn Omholt Gjevestad, and Pål Johan From. "Autonomous Crop Row Guidance Using Adaptive Multi-ROI in Strawberry Fields." Sensors 20, no. 18 (September 14, 2020): 5249. http://dx.doi.org/10.3390/s20185249.
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Automated robotic platforms are an important part of precision agriculture solutions for sustainable food production. Agri-robots require robust and accurate guidance systems in order to navigate between crops and to and from their base station. Onboard sensors such as machine vision cameras offer a flexible guidance alternative to more expensive solutions for structured environments such as scanning lidar or RTK-GNSS. The main challenges for visual crop row guidance are the dramatic differences in appearance of crops between farms and throughout the season and the variations in crop spacing and contours of the crop rows. Here we present a visual guidance pipeline for an agri-robot operating in strawberry fields in Norway that is based on semantic segmentation with a convolution neural network (CNN) to segment input RGB images into crop and not-crop (i.e., drivable terrain) regions. To handle the uneven contours of crop rows in Norway’s hilly agricultural regions, we develop a new adaptive multi-ROI method for fitting trajectories to the drivable regions. We test our approach in open-loop trials with a real agri-robot operating in the field and show that our approach compares favourably to other traditional guidance approaches.
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Song, Hongzhi, Edwin P. Curran, and Roy Sterritt. "Multiple Foci Visualisation of Large Hierarchies with FlexTree." Information Visualization 3, no. 1 (March 2004): 19–35. http://dx.doi.org/10.1057/palgrave.ivs.9500065.
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One of the main tasks in information visualisation research is creating visual tools to facilitate human understanding of large and complex information spaces. Hierarchies, being a good mechanism for organising such information, are ubiquitous. Although much research effort has been spent on finding useful representations for hierarchies, visualising large hierarchies is still a difficult topic. One of the difficulties is how to handle the ever increasing scale of hierarchies. Another is how to enable the user to focus on multiple selections of interest while maintaining context. This paper describes a hierarchy visualisation technique called FlexTree to address these problems. It contains some important features that have not been exploited so far. A profile or contour unique to the hierarchy being visualised can be viewed in a bar chart layout. A normalised view of a common attribute of all nodes can be selected by the user. Multiple foci are consistently accessible within a global context through interaction. Furthermore it can handle a large hierarchy that contains 10,000 nodes in a PC environment. This technique has been applied to visualise computer file system structures and decision trees from data mining results. The results from informal user evaluations against these two applications are also presented. User feedback suggests that FlexTree is suitable for visualising large decision trees.
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Elzinga, Kate, and Edward Buchel. "The Deep Circumflex Iliac Artery Perforator Flap for Breast Reconstruction: Un lambeau perforateur de l’artère iliaque circonflexe profonde pour la reconstruction mammaire." Plastic Surgery 26, no. 4 (November 2018): 229–37. http://dx.doi.org/10.1177/2292550318800329.
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Autologous breast reconstruction using abdominal-based perforator flaps produces excellent aesthetic results with minimal donor site morbidity. The superficial inferior epigastric artery and deep inferior epigastric perforator (DIEP) flaps reliably perfuse a hemi-abdomen, up to the anterior axillary line. Beyond this line laterally, the flank or “love handle” tissue is primarily perfused by the deep circumflex iliac artery (DCIA) or secondarily by the superficial circumflex iliac artery. The flank tissue is a valuable addition to increase flap size when harvested with a DIEP flap or to provide vascularized tissue when the abdomen has been previously harvested. Harvesting the flank tissue in combination with the anterior abdominal tissue improves the contour of the trunk, accentuates the waist, and minimizes secondary revisions to excise prominent “dogears.” The DCIA flap is a novel technique for breast reconstruction. In this article, we describe our technique, pearls and pitfalls, and early results.
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Lin, Li Zong, Xiao Peng Ni, Luo Shan Zhou, and Zhi Qin Qian. "Research on Real-Time Measuring Method of Dynamic Deformation Based on Machine Vision and its Application." Applied Mechanics and Materials 130-134 (October 2011): 3572–76. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3572.
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Dynamic deformation measurement of machine parts in fatigue strength test is studied by using machine vision technique. Considering the uncertainty of parts surface, we adopt circular mark to locate the object profile in order to obtain high quality images. Through some image pre-processing with linear filtering, continuous contour searching method and circular detection based on random Hough transform (RHT), the real-time deformation can be measured with image characteristic parameters. In the practical application, the deformation of the loaded bicycle handle-bar is calculated. The test results show that the machine vision measurement is very effective; measurement resolution attains 0.1mm/pixel; the discrete degree of measurement data is low and the system meets the requirement of real-time measurement. The study proves that the measurement method of dynamic deformation based on machine vision is feasible, which can give some help for fatigue strength test of machine part and other structure deformation.
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Maaloum, M., D. Chretien, E. Karsenti, and J. K. Horber. "Approaching microtubule structure with the scanning tunneling microscope (STM)." Journal of Cell Science 107, no. 11 (November 1, 1994): 3127–31. http://dx.doi.org/10.1242/jcs.107.11.3127.
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We demonstrate that the scanning tunneling microscope can be used to obtain information about arrangement of tubulin subunits in the microtubule wall. Long rows of subunits with a periodicity of 3.8 +/- 0.4 nm were clearly visible in the images of microtubules. The separation between the rows of subunits was 4.8 +/- 0.4 nm. Close inspection of two images revealed another periodicity of 7.8 +/- 0.4 nm in the contour levels of the protofilaments. This indicates that alpha and beta tubulin monomers can be resolved. In these areas the monomers were arranged according to a ‘B-type’ lattice. Scanning tunneling microscope images confirm that the lateral contacts between tubulin monomers in adjacent protofilaments are compatible with a three-start, left-handed helix model. This study demonstrates that scanning tunneling microscopy can give direct information on the structure and organization of macromolecular assemblies and can complement the classical methods of electron microscopy and X-ray scattering.
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Dong, Guo Yan, and Ji Zhou. "Modulation of Optical Transmission in Photonic Crystal." Key Engineering Materials 538 (January 2013): 42–45. http://dx.doi.org/10.4028/www.scientific.net/kem.538.42.
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The transmission properties of electromagnetic wave (EMW) can be modulated by the periodic structure of photonic crystal (PhC) to bring many novel optical effects. The special distributions of equal frequency contours (EFCs) can be used to control the wavefront state and transmission direction of propagating wave in PhC with some special effects, such as non-handed refraction. Based on the intricate undulation of one single band or the overlap of different bands, the phenomena of dual-negative refraction, symmetrical positive-negative refraction and triple refraction have been achieved in the higher band regions. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical devices.
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Kong, Yong-Ku, Soo-Jin Lee, Brian D. Lowe, and Seongho Song. "Evaluation of Various Handle Grip Spans for Optimizing Finger Specific Force Based on the Users' Hand Sizes." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 51, no. 15 (October 2007): 884–88. http://dx.doi.org/10.1177/154193120705101504.
Full textAbstract:
This study evaluated the effects of handle grip span and user's hand size on maximum grip strength and individual finger force using a computerized digital dynamometer with five various grip spans (45, 50, 55, 60, and 65mm). Forty-six males participated and were assigned into three hand size groups (small, middle, large) according to their hand lengths. Results showed that generally 55 and 50mm grip spans had the highest grip strength (433.6N and 430.8N, respectively), whereas 65mm grip span had the least grip strength. With respect to the interaction effect of grip span and hand size, small hand sized participants produced the highest grip forces at the 45mm grip span, followed by 50 and 55mm, middle hand size participants provided the highest grip force at the 55mm followed by 50 and 45mm, whereas large hand size participants exerted the highest grip force at the 55mm followed by 60mm. In the analysis of individual finger force, the middle finger force was the strongest and the highest contribution (37.5%) to the total finger force, followed by ring (28.7%), index (20.2%) and little (13.6%) fingers. In addition, it was noted that each finger had a different optimal grip span for exerting maximum force, resulting in a bowed contoured shaped handle (i.e., the grip span of the handle at the center is larger than that of the handle at the end) for two-handle hand tools.
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Xu, Jia, Kun Qu, and Jin Sheng Cai. "Flow Simulations for NASA CRM Wing-Body-Tail with Implicit Hole Cutting Method." Applied Mechanics and Materials 378 (August 2013): 355–61. http://dx.doi.org/10.4028/www.scientific.net/amm.378.355.
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The overset grid method eases the time of grid generation and provides great flexibility to handle topologically complex configurations, but the generation for a system of overlapping grids is an expensive and daunting task. Based on a hierarchical overset grid strategy, implicit holt cutting method developed to ensure grid connectivity within a framework suitable for multi-grid. Viscous flows around NASA CRM wing-body-tail configuration were simulated by an in-house CFD solver called Exstream. Compared with CFL3D and OVERFLOW, The results of Exstream show that: the smooth transition of surface pressure contour in the overlapping region indicates that the interpolation between the overlapping grids can offer sufficient accuracy, and it demonstrates the accuracy and efficiency of implicit holt cutting method and Exstream solver. The lift data matches well with those of CFL3D, OVERFLOW and Exstream and follows a nearly linear trend as angle of attack varies from 0.00 to 3.00 deg. In addition, there is a flow separation bubble near the trailing edge of wing-fuselage junction.
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Aslankurt, Murat, Lokman Aslan, Adnan Aksoy, Murat Özdemir, and Şenol Dane. "Laterality Does Not Affect the Depth Perception, but Interpupillary Distance." Journal of Ophthalmology 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/485059.
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In this study, which investigates the relationship between the levels of stereopsis with eye and hand dominance or interpupillary distance, 120 healthy young volunteers were investigated. Eye dominance was determined by modified Miles technique following a complete eye examination. Handedness was assessed with the Edinburgh handedness inventory. Interpupillary distance was measured with millimetric ruler. Stereoacuity was measured in both contour (Titmus test) and random dot (TNO test) stereograms. The stereopsis scores were evaluated in terms of hand or eye dominance. The correlation between stereopsis score and interpupillary distance was assessed. Main outcome measures were stereopsis scores according to hand and eye dominance. As a result, right- and left-handed individuals showed no differences in terms of stereopsis. No differences were found in stereopsis scores between right- and left-eye dominant people. There was a correlation between interpupillary distance and the depth of stereopsis (r=-0.248,P<0.05). Contrary to the expectation, the left and right dominant individuals did not differ in levels of stereopsis. Interpupillary distance has a positive effect on stereopsis.
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Edrisi, A. R. R., and S. I. I. Kam. "A New Foam Model in Pipes for Drilling and Fracturing Applications." SPE Journal 19, no. 04 (August 26, 2013): 576–85. http://dx.doi.org/10.2118/162709-pa.
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Summary A series of recent experimental studies revealed that foam flow can be represented by two distinct flow regimes in general—low-quality regime, showing stable plug-flow pattern, and high-quality regime, showing unstable slug-flow pattern. This study, for the first time, presents how to develop a comprehensive foam model that can handle a variety of bubble-size distributions and both stable and unstable flow patterns with a two-flow-regime concept. Building an improved foam model on the basis of such a new concept can potentially help to better design and optimize many foam-associated processes including tight-gas and shale-gas foam fracturing, foam underbalanced drilling, foam liquid unloading, and cuttings transport. Analyzing the experimental data of surfactant foams and polymer-added foams shows that (i) in the low-quality regime, foam rheology is governed by bubble slippage at the wall with no significant change in its fine foam texture and (ii) in the high-quality regime, foam rheology is governed by the relative size of free-gas segment to fine-textured foam-slug segment. With these governing mechanisms, this improved foam model successfully reproduces foam-flow characteristics as observed in the experiments, including almost-horizontal pressure contours in the low-quality regime and inclined pressure contours in the high-quality regime. Although the model is built with a power-law fluid model, the same procedure can be applied for Bingham-plastic or yield-power-law fluids.
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Dong, Guo Yan, and Ji Zhou. "Anomalous Optical Transmission Phenomena in Photonic Crystals." Applied Mechanics and Materials 320 (May 2013): 128–32. http://dx.doi.org/10.4028/www.scientific.net/amm.320.128.
Full textAbstract:
Anomalous optical transmission phenomena have ever been discovered in various metamaterials, which can be modulated more easily in Photonic crystals (PhCs). Compared with the regular PhCs composed of round rods closely packed in air, the equal frequency contours (EFC) of honeycomb lattice PhCs constituted by trigonal rods are more rounded and more suitable to realize the all-angle left-handed negative refraction (AALNR) in the low band region. Due to the hex EFC distribution, the regular PhC can be applied in the optical collimator design. In the higher band regions, the more complicated refraction behaviors can be excited based on the intricate undulation of one band or the overlap of different bands in PhCs. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical devices.