Articoli di riviste: "3D Elliptical Fourier Descriptors"

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Jeong, Yongwon, e Richard J. Radke. "Reslicing axially sampled 3D shapes using elliptic Fourier descriptors". Medical Image Analysis 11, n. 2 (aprile 2007): 197–206. http://dx.doi.org/10.1016/j.media.2006.12.003.

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Prpić-Oršić, Jasna, Marko Valčić e Zoran Čarija. "A Hybrid Wind Load Estimation Method for Container Ship Based on Computational Fluid Dynamics and Neural Networks". Journal of Marine Science and Engineering 8, n. 7 (20 luglio 2020): 539. http://dx.doi.org/10.3390/jmse8070539.

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Abstract (sommario):

The estimation of wind loads on ships and other marine objects represents a continuous challenge because of its implication for various aspects of exposed structure exploitation. An extended method for estimating the wind loads on container ships is presented. The method uses the Generalized Regression Neural Network (GRNN), which is trained with Elliptic Fourier Descriptors (EFD) of sets of frontal and lateral closed contours as inputs. Wind load coefficients (Cx, Cy, CN), used as outputs for network training, are derived from 3D steady RANS CFD analysis. This approach is very suitable for assessing wind loads on container ships wherever there is a wind load database for a various container configuration. In this way, the cheaper and faster calculation can bridge the gap for the container configurations for which calculations or experiments have not already been made. The results obtained by trained GRNN are in line with available experimental measurements of the wind loads on various container configuration on the deck of a 9000+ TEU container ship obtained through a series of wind tunnel tests, as well as with performed CFD simulation for the same conditions.

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Wu, Ge, Duan Li, Pengpeng Hu, Yueqi Zhong e Ning Pan. "Foot shape prediction using elliptical Fourier analysis". Textile Research Journal 88, n. 9 (17 febbraio 2017): 1026–37. http://dx.doi.org/10.1177/0040517517693983.

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In this paper, a new method was proposed to establish the relationship between three-dimensional (3D) foot shapes and their two-dimensional (2D) foot silhouettes, through which a complete 3D foot shape can be predicted by simply inputting its two 2D silhouettes. 3D foot scans of 80 participants were randomly selected as the training set, and those of another 20 participants were used as the testing set. Elliptical Fourier analysis (EFA) and principle component analysis (PCA) were adopted to parameterize the 3D foot shapes. A linear regressive model was then developed to predict the 3D foot shape with the foot silhouettes. Experiment results indicated individual 3D foot shape can be predicted with a mean error between 1.21 and 1.27 mm, which can provide enough accuracy for the fit evaluation of footwear.

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Mollon, Guilhem, e Jidong Zhao. "Generating realistic 3D sand particles using Fourier descriptors". Granular Matter 15, n. 1 (30 ottobre 2012): 95–108. http://dx.doi.org/10.1007/s10035-012-0380-x.

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López-Sampson, Arlene, e Tony Page. "Elliptical Fourier Descriptors of Leaf Outlines: A Tool to Discriminate Among Aquilaria Species (Thymelaeaceae)". Silvae Genetica 67, n. 1 (1 settembre 2018): 89–92. http://dx.doi.org/10.2478/sg-2018-0012.

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Abstract Leaf shape analysis of three Aquilaria species was undertaken using Elliptical Fourier descriptors (EFD) within a research planting in tropical Australia. This approach was taken to develop a method for discriminating the species in the absence of reproductive traits or genetic analysis and as a morphological scale of leaf variation. Leaf outlines were analysed to distinguish variability between species. Principal components analysis and canonical discriminant analysis were applied to group the species based on 25 Fourier descriptors. Four components were required to explain 78 % of the variance and the first and second canonical functions discriminated three groups of species therefore EFD was a useful approach for analysing leaf outline variability and distinguish species in the genus Aquilaria. This approach provides a rapid method that could assist in the species identification in Aquilaria where reproductive traits are absent.

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Kwok, S. K. W., e J. C. H. Poon. "Viewpoint-invariant Fourier descriptors for 3D planar shape representation". Electronics Letters 32, n. 19 (1996): 1775. http://dx.doi.org/10.1049/el:19961217.

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Wu, M. F., e H. T. Sheu. "Representation of 3D surfaces by two-variable Fourier descriptors". IEEE Transactions on Pattern Analysis and Machine Intelligence 20, n. 8 (1998): 858–63. http://dx.doi.org/10.1109/34.709610.

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Wu, Ming-Fang, e Hsin-Teng Sheu. "3D invariant estimation of axisymmetric objects using fourier descriptors". Pattern Recognition 29, n. 2 (febbraio 1996): 267–80. http://dx.doi.org/10.1016/0031-3203(95)00088-7.

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9

Stransky, Christoph, e Shayne E. MacLellan. "Species separation and zoogeography of redfish and rockfish (genus Sebastes) by otolith shape analysis". Canadian Journal of Fisheries and Aquatic Sciences 62, n. 10 (1 ottobre 2005): 2265–76. http://dx.doi.org/10.1139/f05-143.

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Interspecific otolith shape variation was investigated within the species-rich genus Sebastes (redfish, rockfish) as a tool for species separation, since morphological distinction has proven to be difficult. Otolith samples from all four North Atlantic redfish species, six commercially important rockfish species from the North Pacific, and Sebastes capensis from the South Atlantic were compared for differences in linear otolith measurements and elliptical Fourier-shape descriptors. A clear distinction between the North Atlantic and North Pacific / South Atlantic species (97% correct jackknifed classification) was achieved by univariate measurements and discriminant analysis of size-corrected Fourier descriptors. Overall species classification success was 91%, 94% within the North Pacific species and 88% within the North Atlantic samples. From the Pacific rockfish, Sebastes alutus otoliths showed the strongest affinity to the North Atlantic Sebastes. High similarity of otolith shapes of S. capensis to the North Pacific Sebastes and clear discrimination from North Atlantic species coincide with current zoogeographical and speciation theories, as well as with recently reported genetic results.

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LIN, SHENG-FUU, CHIN-CHIA WU, CHI-YAO HSU e DOU-CHIH HSU. "AN EFFICIENT 3D MODEL RETRIEVAL BASED ON PRINCIPAL AXES ANALYSIS AND FEATURE INTEGRATION". International Journal of Pattern Recognition and Artificial Intelligence 25, n. 04 (giugno 2011): 583–604. http://dx.doi.org/10.1142/s0218001411008749.

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Three-dimensional (3D) model retrieval has gathered great importance in recent years, since the number of available 3D models on the Internet has drastically increased. Many content-based 3D model retrieval approaches have been proposed. Among these methods, visual similarity-based methods have shown higher retrieval accuracy. However, because these methods capture enormous shape features from different viewpoints or locations, a large amount of calculation and comparison is necessary. Furthermore, there is a trade-off between retrieval accuracy and speed. In this paper, a 3D model retrieval method constituting Continuous Principal Component Analysis (CPCA), Fourier descriptors, and Zernike moments is proposed. CPCA is applied to extract significant shape features based on projecting the model along the principal axes. Then, Fourier descriptors and Zernike moments are used to provide shape descriptors with rotation invariants. In addition, a feature integration process combines them. A strategy of similarity measure is proposed to solve the axes switching problem. To conclude, the experimental results show that the approach outperforms SECTORS2 and D2,18 and has slightly better retrieval results than Light Field Descriptor (LFD)6 and spin-image signatures.3 Moreover, the approach is more efficient and the storage size is much less.

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Cerna, Francisco, Juan Carlos Saavedra-Nievas, Guido Plaza-Pasten, Edwin Niklitschek e Beatriz Morales-Nin. "Ontogenetic and intraspecific variability in otolith shape of anchoveta (Engraulis ringens) used to identify demographic units in the Pacific Southeast off Chile". Marine and Freshwater Research 70, n. 12 (2019): 1794. http://dx.doi.org/10.1071/mf18278.

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The phenotypical variability in otolith shape of anchoveta (Engraulis ringens) was analysed in three zones (I, II and III) from north to south along the Chilean coast, using juvenile and adult fish. Generalised additive models were used to analyse shape indices and canonical discriminant analysis was used to analyse elliptical Fourier harmonics. The form factor and ellipticity indices varied significantly among the three zones, whereas roundness, circularity and rectangularity indices only showed differences between Zones I and III. Fourier reconstructed outlines for five ontogenetic stages suggested important differences among sampling zones, which were larger for sampling Zone III, where, at the same fish length, otoliths were smaller than those sampled in Zones I and II, at least at the pre-recruit stage. Elliptical Fourier descriptors showed significant differences among the three units, with a total percentage of correct classifications for juveniles of 89 and 74% for raw data and cross-validated cases respectively, compared with >85 and ~65% respectively for adult fish. The results support the hypothesis that juveniles and adults of anchoveta have remained segregated throughout their entire, or at least a fraction of, their life cycle, mainly between the extreme northward and southward zones.

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Safaee-Rad, R., K. C. Smith, B. Benhabib e I. Tchoukanov. "Application of moment and Fourier descriptors to the accurate estimation of elliptical-shape parameters". Pattern Recognition Letters 13, n. 7 (luglio 1992): 497–508. http://dx.doi.org/10.1016/0167-8655(92)90067-a.

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STETTEN, GEORGE D., e REBEKAH DREZEK. "ACTIVE FOURIER CONTOUR APPLIED TO REAL TIME 3D ULTRASOUND OF THE HEART". International Journal of Image and Graphics 01, n. 04 (ottobre 2001): 647–58. http://dx.doi.org/10.1142/s0219467801000347.

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We describe an active contour based on the elliptical Fourier series, and its application to matrix-array ultrasound. Matrix-array, or Real Time 3D (RT3D), ultrasound is a relatively new medical imaging modality that scans a 3D-volume electronically without physically moving the transducer, allowing for real-time continuous 3D imaging of the heart. With the goal of automatically tracking the heart wall, an active contour has been developed using the elliptical Fourier series to find perpendicular lines intersecting an initial contour. The neighborhood defined by these perpendiculars is mapped into a rectangular space, called a swath, whose vertical axis represents the inside-vs-outside dimension of the contour (perpendicular to the contour), and whose horizontal axis represents parametric distance along the contour (tangent to the contour). A dynamic programming technique is then used to find the optimum error function traversing the rectangle horizontally, and this error function is mapped back into image space to yield a new contour. The method does not iterate, but rather simultaneously searches for the optimum contour within a limited domain. Results are presented applying the technique to RT3D ultrasound images of in vivo hearts.

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Abdusslam Osman Beitalmal. "Efficient 3D Surface Patch Compression and Reconstruction using Parametric Descriptions and Transform Techniques". Journal of Pure & Applied Sciences 22, n. 1 (30 giugno 2023): 107–16. http://dx.doi.org/10.51984/jopas.v22i1.2164.

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This paper proposes and demonstrates novel methods for compressing and reconstructing 3D surface patches typically obtained from scanners that rely on stereo vision, structured light, or time-of-flight techniques. The methods involve applying a polygon reduction to the mesh to get a set of vertices lying in structured planes of a sparse, regular grid. The data in each plane is then described parametrically, and a comparative analysis is conducted using the Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT), and Discrete Wavelet Transform (DWT). Quality factors are employed to further process the transform coefficients, resulting in substantial reductions in the amount of data saved to disk. The paper also defines file formats with the necessary parameters for a complete reconstruction of the sparse mesh. Finally, elliptic Partial Differential Equations (PDE) are used to represent the reconstructed data, and the Laplace equation is iteratively solved between adjacent planes to recover the vertex density of the original mesh. Experimental results demonstrate the effectiveness of the proposed methods, achieving compression rates of over 98% compared to the OBJ file format and over 91% compared to a list of vertices in ASCII format.

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Schmittbuhl, Matthieu, Jean-Marie Le Minor, André Schaaf e Patrice Mangin. "The human mandible in lateral view: elliptical fourier descriptors of the outline and their morphological analysis". Annals of Anatomy - Anatomischer Anzeiger 184, n. 2 (marzo 2002): 199–207. http://dx.doi.org/10.1016/s0940-9602(02)80021-8.

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Godefroy, Jérémy E., Fabien Bornert, Catherine I. Gros e André Constantinesco. "Elliptical Fourier descriptors for contours in three dimensions: A new tool for morphometrical analysis in biology". Comptes Rendus Biologies 335, n. 3 (marzo 2012): 205–13. http://dx.doi.org/10.1016/j.crvi.2011.12.004.

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Wu, Ge, Zhicai Yu, Azmat Hussain e Yueqi Zhong. "3D Drape Reconstruction and Parameterization Based on Smartphone Video and Elliptical Fourier Analysis". Procedia Computer Science 108 (2017): 1552–61. http://dx.doi.org/10.1016/j.procs.2017.05.057.

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Harbitz, Alf. "Parameter-sparse modification of Fourier methods to analyse the shape of closed contours with application to otolith outlines". Marine and Freshwater Research 67, n. 7 (2016): 1049. http://dx.doi.org/10.1071/mf15087.

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Abstract (sommario):

Elliptical Fourier descriptors (EFDs) have been used extensively in shape analysis of closed contours and have a range of marine applications, such as automatic identification of fish species and discrimination between fish stocks based on EFDs of otolith contours. A recent method (the ‘MIRR’ method) transforms the two-dimensional contour to a one-dimensional function by mirroring (reflecting) the lower half of the contour around a vertical axis at the right end of the contour. MIRR then applies the fast Fourier transform (FFT) to the vertical contour points corresponding to equidistant coordinate values along the horizontal axis. MIRR has the advantage of reducing the number of Fourier coefficients to two coefficients per frequency component compared with four EFDs. However, both Fourier methods require several frequency components to reproduce a pure ellipse properly. This paper shows how the methods can be easily modified so that a virtually perfect reproduction of a pure ellipse is obtained with only one frequency component. In addition, real otolith examples for cod (Gadus morhua) and Greenland halibut (Reinhardtius hippoglossoides) are used to demonstrate that the modified methods give better approximations to the large-scale shape of the original contour with fewer coefficients than the traditional Fourier methods, with negligible additional computing time.

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Wang, Xiao, Juan Wang, Xin Wang e Chujun Yu. "A Pseudo-Spectral Fourier Collocation Method for Inhomogeneous Elliptical Inclusions with Partial Differential Equations". Mathematics 10, n. 3 (19 gennaio 2022): 296. http://dx.doi.org/10.3390/math10030296.

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Inhomogeneous elliptical inclusions with partial differential equations have aroused appreciable concern in many disciplines. In this paper, a pseudo-spectral collocation method, based on Fourier basis functions, is proposed for the numerical solutions of two- (2D) and three-dimensional (3D) inhomogeneous elliptic boundary value problems. We describe how one can improve the numerical accuracy by making some extra “reconstruction techniques” before applying the traditional Fourier series approximation. After the particular solutions have been obtained, the resulting homogeneous equation can then be calculated using various boundary-type methods, such as the method of fundamental solutions (MFS). Using Fourier basis functions, one does not need to use large matrices, making accrual computations relatively fast. Three benchmark numerical examples involving Poisson, Helmholtz, and modified-Helmholtz equations are presented to illustrate the applicability and accuracy of the proposed method.

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Sánchez, Carlos, Gabriel Cristóbal e Gloria Bueno. "Diatom identification including life cycle stages through morphological and texture descriptors". PeerJ 7 (25 aprile 2019): e6770. http://dx.doi.org/10.7717/peerj.6770.

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Diatoms are unicellular algae present almost wherever there is water. Diatom identification has many applications in different fields of study, such as ecology, forensic science, etc. In environmental studies, algae can be used as a natural water quality indicator. The diatom life cycle consists of the set of stages that pass through the successive generations of each species from the initial to the senescent cells. Life cycle modeling is a complex process since in general the distribution of the parameter vectors that represent the variations that occur in this process is non-linear and of high dimensionality. In this paper, we propose to characterize the diatom life cycle by the main features that change during the algae life cycle, mainly the contour shape and the texture. Elliptical Fourier Descriptors (EFD) are used to describe the diatom contour while phase congruency and Gabor filters describe the inner ornamentation of the algae. The proposed method has been tested with a small algae dataset (eight different classes and more than 50 samples per type) using supervised and non-supervised classification techniques obtaining accuracy results up to 99% and 98% respectively.

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Gao, Xue-Yao, Bo-Yu Yang e Chun-Xiang Zhang. "Combine EfficientNet and CNN for 3D model classification". Mathematical Biosciences and Engineering 20, n. 5 (2023): 9062–79. http://dx.doi.org/10.3934/mbe.2023398.

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<abstract> <p>With the development of multimedia technology, the number of 3D models on the web or in databases is becoming increasingly larger and larger. It becomes more and more important to classify and retrieve 3D models. 3D model classification plays important roles in the mechanical design field, education field, medicine field and so on. Due to the 3D model's complexity and irregularity, it is difficult to classify 3D model correctly. Many methods of 3D model classification pay attention to local features from 2D views and neglect the 3D model's contour information, which cannot express it better. So, accuracy the of 3D model classification is poor. In order to improve the accuracy of 3D model classification, this paper proposes a method based on EfficientNet and Convolutional Neural Network (CNN) to classify 3D models, in which view feature and shape feature are used. The 3D model is projected into 2D views from different angles. EfficientNet is used to extract view feature from 2D views. Shape descriptors D1, D2, D3, Zernike moment and Fourier descriptors of 2D views are adopted to describe the 3D model and CNN is applied to extract shape feature. The view feature and shape feature are combined as discriminative features. Then, the softmax function is used to determine the 3D model's category. Experiments are conducted on ModelNet 10 dataset. Experimental results show that the proposed method achieves better than other methods.</p> </abstract>

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Zhbadynskyi, Igor. "Concentration of dynamic stresses in an elastic space with twoperiodic array of elliptical cracks". Physico-mathematical modelling and informational technologies, n. 28, 29 (27 dicembre 2019): 18–25. http://dx.doi.org/10.15407/fmmit2020.28.018.

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Normal incidence of the plane time-harmonic longitudinal wave on double-periodic array of coplanar elliptical cracks, which are located in 3D infinite elastic space is considered. Corresponding symmetric wave scattering problem is reduced to a boundary integral equation for the displacement jump across the crack surfaces in a unit cell by means of periodic Green’s function, which is presented in the form of Fourier integrals. A regularization technique for this Green’s function involving special lattice sums in closed forms is adopted, which allows its effective calculation in a wide range of wave numbers. The boundary integral equation is correctly solved by using the mapping method. The frequency dependencies of mode-I stress intensity factor in the vicinity of the crack front points for periodic distances in the system of elliptical cracks are revealed.

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Cañás, Lucía, Christoph Stransky, Jürgen Schlickeisen, M. Paz Sampedro e A. Celso Fariña. "Use of the otolith shape analysis in stock identification of anglerfish (Lophius piscatorius) in the Northeast Atlantic". ICES Journal of Marine Science 69, n. 2 (1 marzo 2012): 250–56. http://dx.doi.org/10.1093/icesjms/fss006.

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Abstract Cañás, L., Stransky, C., Schlickeisen, J., Sampedro, M. P., and Fariña, A. C. 2012. Use of the otolith shape analysis in stock identification of anglerfish (Lophius piscatorius) in the Northeast Atlantic. – ICES Journal of Marine Science, 69: 250–256. The geographical variability in the anglerfish Lophius piscatorius otolith shape was investigated to examine biological evidence for the current separation into Northern and Southern stocks of L. piscatorius established in the Southwest European waters (Southern Shelf area) by the International Council for the Exploration of the Sea (ICES). In all, 629 otoliths of L. piscatorius (12–90 cm total length) from commercial fishing and research surveys were collected in two consecutive years, 2008 and 2009. The otolith shape was compared between stocks for differences in univariate descriptors using non-parametric analysis of covariance, as well as elliptical Fourier shape descriptors, through a metric multidimensional scaling and a linear discriminant analysis (LDA). The differences found in the otolith shape between Northern and Southern stocks were not large enough to hold the current status of L. piscatorius regarding stock definition in the Southern Shelf area, although homogeneous mixing between both stocks is not expected as there were significant differences between three univariate descriptors and the LDA was significant. These results are in agreement with the previous L. piscatorius stock identification studies (genetics, body morphology, and migratory behaviour), which do not support the current separation of these stocks but found substructures within the area.

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Morawicki, Santiago, Patricio J. Solimano e Alejandra V. Volpedo. "Unravelling Stock Spatial Structure of Silverside Odontesthes argentinensis (Valenciennes, 1835) from the North Argentinian Coast by Otoliths Shape Analysis". Fishes 7, n. 4 (29 giugno 2022): 155. http://dx.doi.org/10.3390/fishes7040155.

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The marine silverside (Odontesthes argentinensis) is an euryhaline species, distributed along the southwest coast of the Atlantic Ocean, present in estuaries, brackish coastal lagoons and shallow marine waters. It is a significant economic resource for local fisheries in southern Brazil, Uruguay and Argentina. The aim of this work was to contribute to knowledge on the stock spatial structure of the silverside, using otolith shape analysis, based on samples from nine locations in the Argentinian Sea, covering a large distribution range of the species. A combination of elliptic Fourier descriptors, Wavelet coefficients and otolith Shape indices were explored by multivariate statistical methods. The application of wavelet and combined wavelet, Fourier and Shape Indices were the most effective variables to discriminate between sampling sites (7.42 total error). PERMANOVA analysis of otolith shape revealed multivariate significant differences between north versus south locations (p < 0.0001). The results obtained show that the spatial structure of O. argentinensis presents a North–South gradient with marked differences between the extreme localities of the north (Mar del Plata, Quequén) with more elliptical shapes than those in the south (San Blas, San Antonio Este) and an isolated group conformed by Puerto Lobos.

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Mollon, Guilhem, e Jidong Zhao. "3D generation of realistic granular samples based on random fields theory and Fourier shape descriptors". Computer Methods in Applied Mechanics and Engineering 279 (settembre 2014): 46–65. http://dx.doi.org/10.1016/j.cma.2014.06.022.

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Ren, Yue, Wenqing Fu, Yi Gao, Yuhan Chen, Decang Kong, Ming Cao, Xiaoming Pang e Wenhao Bo. "Identification of Key Genes of Fruit Shape Variation in Jujube with Integrating Elliptic Fourier Descriptors and Transcriptome". Plants 13, n. 9 (5 maggio 2024): 1273. http://dx.doi.org/10.3390/plants13091273.

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Jujube (Ziziphus jujuba) exhibits a rich diversity in fruit shape, with natural occurrences of gourd-like, flattened, and other special shapes. Despite the ongoing research into fruit shape, studies integrating elliptical Fourier descriptors (EFDs) with both Short Time-series Expression Miner (STEM) and weighted gene co-expression network analysis (WGCNA) for gene discovery remain scarce. In this study, six cultivars of jujube fruits with distinct shapes were selected, and samples were collected from the fruit set period to the white mature stage across five time points for shape analysis and transcriptome studies. By combining EFDs with WGCNA and STEM, the study aimed to identify the critical periods and key genes involved in the formation of jujube fruit shape. The findings indicated that the D25 (25 days after flowering) is crucial for the development of jujube fruit shape. Moreover, ZjAGL80, ZjABI3, and eight other genes have been implicated to regulate the shape development of jujubes at different periods of fruit development, through seed development and fruit development pathway. In this research, EFDs were employed to precisely delineate the shape of jujube fruits. This approach, in conjunction with transcriptome, enhanced the precision of gene identification, and offered an innovative methodology for fruit shape analysis. This integration facilitates the advancement of research into the morphological characteristics of plant fruits, underpinning the development of a refined framework for the genetic underpinnings of fruit shape variation.

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Petitprez, Etienne, François Guérin, Frédéric Guinand, Florian Germain e Nicolas Kerthe. "Decentralized Coordination of a Multi-UAV System for Spatial Planar Shape Formations". Sensors 23, n. 23 (1 dicembre 2023): 9553. http://dx.doi.org/10.3390/s23239553.

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Motivated by feedback from firefighters in Normandy, this work aims to provide a simple technique for a set of identical drones to collectively describe an arbitrary planar virtual shape in a 3D space in a decentralized manner. The original problem involved surrounding a toxic cloud to monitor its composition and short-term evolution. In the present work, the pattern is described using Fourier descriptors, a convenient mathematical formulation for that purpose. Starting from a reference point, which can be the center of a fire, Fourier descriptors allow for more precise description of a shape as the number of harmonics increases. This pattern needs to be evenly occupied by the fleet of drones under consideration. To optimize the overall view, the drones must be evenly distributed angularly along the shape. The proposed method enables virtual planar shape description, decentralized bearing angle assignment, drone movement from takeoff positions to locations along the shape, and collision avoidance. Furthermore, the method allows for the number of drones to change during the mission. The method has been tested both in simulation, through emulation, and in outdoor experiments with real drones. The obtained results demonstrate that the method is applicable in real-world contexts.

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Vaz-dos-Santos, André Martins, Kathleen Angélica Rautenberg, Cristiane Gallego Augusto, Eduardo Luis Cupertino Ballester, Paulo Ricardo Schwingel, Edgar Pinto, Agostinho Almeida e Alberto Teodorico Correia. "Geographic Variation in Opisthonema oglinum (Lesueur, 1818) in the Southeastern Brazilian Bight Inferred from Otolith Shape and Chemical Signatures". Fishes 8, n. 5 (29 aprile 2023): 234. http://dx.doi.org/10.3390/fishes8050234.

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The thread herring Opisthonema oglinum (Lesueur, 1818) is a small pelagic fish distributed in the western margin of the Atlantic Ocean from the United States to Argentina. It is a target species for diverse commercial fisheries, including the Brazilian industrial purse seine fleets that operate in the Southeastern Brazilian Bight. To investigate the geographic variation in the thread herring populations in this fishing ground, sagittal otoliths were collected from two areas: Rio de Janeiro (RJ: 23°04′ S, 44°03′ W) and Santa Catarina (SC: 26°05′ S, 48°18′ W). Otolith shape analyses and multi-elemental signatures were statistically evaluated using elliptical Fourier descriptors and elemental/Ca ratios. Remarkable differences in the thread herring otoliths between the two areas were found. The previous scenario in which the thread herring constitutes a single panmictic population in the Atlantic Ocean is now debatable. The implications of these results in terms of rational fisheries management for this species are highlighted.

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Wang, Jin, Wei Qian e Guoke Chen. "Combining quantitative analysis with an elliptic Fourier descriptor: A study of pottery from the Gansu-Zhanqi site based on 3D scanning and computer technology". Journal of Archaeological Science: Reports 36 (aprile 2021): 102897. http://dx.doi.org/10.1016/j.jasrep.2021.102897.

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Andrialovanirina, Nicolas, Émilie Poisson Caillault, Sébastien Couette, Rémi Laffont, Lauriane Poloni, Camille Lutet-Toti e Kélig Mahé. "Asymmetry of Sagittal Otolith Shape Based on Inner Ear Side Tested on Mediterranean Red Mullet (Mullus barbatus Linnaeus, 1758): Comparative Analysis of 2D and 3D Otolith Shape Data". Symmetry 15, n. 5 (11 maggio 2023): 1067. http://dx.doi.org/10.3390/sym15051067.

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Sagittal otolith shape analysis is one of the most widespread techniques worldwide to discriminate fish stock units, as this proxy integrates both environmental and genetic factors. All previous otolith shape studies have been carried out using two-dimensional (2D) images, a partial representation of the whole shape of the otolith. However, prior to the identification of stock unit boundaries, the influence of other potential drivers controlling the otolith shape must be analysed to limit their bias. In this study, the presence of asymmetry in otolith shape depending on the inner ear side (i.e., left versus right inner ears) was tested by comparing the approaches of 2D and three-dimensional (3D) sagittal otolith shape analyses. Eighty-two red mullet adults (Mullus barbatus) from three locations in the eastern part of the Mediterranean Sea were studied. Fourier harmonic descriptors computed from 2D outlines and spherical harmonic descriptors computed from 3D meshes were used to evaluate otolith shape variation. The results of a multivariate mixed-effects model from 2D images showed that there was no asymmetry effect of inner ear side on the otolith shape in any location. There was, however, a significant geographical effect for the 2D otolith shape between the Adriatic Sea and the Levantine Sea. In contrast, 3D information showed that both side effects and geographical differences were significant. This is the first study comparing 2D and 3D data showing different results on the same sample of red mullet. These results demonstrate the importance of 3D otolith shape analysis for stock discrimination.

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Lu, Mingming, Bin Chen, Dongpo Zhao, Jiakang Zhou, Jieqiong Lin, Allen Yi e Hao Wang. "Chatter Identification of Three-Dimensional Elliptical vibration Cutting Process Based on Empirical Mode Decomposition and Feature Extraction". Applied Sciences 9, n. 1 (21 dicembre 2018): 21. http://dx.doi.org/10.3390/app9010021.

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Three-dimensional elliptical vibration cutting (3D-EVC) is one of the machining methods with the most potential in ultra-precision machining; its unique characteristics of intermittent cutting, friction reversal, and ease of chip removal can improve the machinability of materials in the cutting processes. However, there is still not much research about the chattering phenomenon in the 3D-EVC process. Therefore, based on the empirical mode decomposition (EMD) technique and feature extraction, a chatter identification method for 3D-EVC is proposed. In 3D-EVC operations, the vibration signal is collected by the displacement sensors and converted to frequency domain signal by fast Fourier transform (FFT). To identify tool cutting state using the vibration frequency signal, the vibration signals are decomposed using empirical mode decomposition (EMD), a series of intrinsic mode functions (IMFs), so the instantaneous frequency can be reflected by the vibration signals at any point. Then, selecting the primary IMFs which contain rich chatter information as the object in feature extraction identification, and two identification indexes, that is, the mean square frequency and self-correlation coefficient, are calculated for the primary IMFs by MATLAB software, to judge the chatter phenomenon. The experimental results showed that the mean square frequency and self-correlation coefficient of the three cutting states increase with the increase in the instability of the cutting state. The effectiveness of the improved chatter recognition method in 3D-EVC machining is verified.

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Samuel, O. M., P. M. Casanova e J. O. Olopade. "Elliptical Fourier descriptors of outline and morphological analysis in caudal view of foramen magnum of the tropical raccoon ( Procyon cancrivorus ) (Linnaeus, 1758)". Morphologie 102, n. 336 (marzo 2018): 31–40. http://dx.doi.org/10.1016/j.morpho.2017.06.001.

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Khedher, Maissa, Marwa Mejri, Adel A. Basyouny Shahin, Jean-Pierre Quiganrd, Monia Trabelsi e Abderraouf Ben Faleh. "Discrimination of Diplodus vulgaris (Actinopterygii, Sparidae) stock from two Tunisian lagoons using otolith shape analysis". Journal of the Marine Biological Association of the United Kingdom 101, n. 4 (giugno 2021): 743–51. http://dx.doi.org/10.1017/s0025315421000667.

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AbstractSaccular otolith shape and size were analysed for the first time in 120 adult individuals of D. vulgaris collected from two localities, the Bizerte and Ghar El Melh lagoons (north-east Tunisia). The objectives were (1) to examine the specific inter- and intra-individual variation in the otolith shape using elliptical Fourier analysis combined with measures of length (LO), width (WO) and area (AO); (2) to use the otolith shape and size analysis as a phenotypic-based approach to discriminate the stock structure of this species in the two localities to investigate whether they represent two separate stocks to inform on appropriate management procedures; and (3) to test for biases resulting from potential fluctuating asymmetry (FA) in the otolith size on the discrimination of stock structure. Discriminant function analysis performed with the normalized elliptical Fourier descriptors coefficients showed statistically significant differences (P < 0.0001) in the otolith contour shape, i.e. asymmetry, either between the left and right sides or between the same sides (left-left and right-right) within and among individuals of the two localities. Besides, a significant asymmetry (P < 0.05) was found in WO and AO among individuals within the Bizerte locality and in WO only within the Ghar El Melh locality. Moreover, significant FA was observed in the otolith size parameters among individuals of the two localities. This significant asymmetry detected in the otolith shape, as well as in the size due to FA, within and among individuals of D. vulgaris collected from the Bizerte and Ghar El Melh localities confirms that the two stocks could be discriminated from each other and should be managed separately. This asymmetry is discussed in light of the instability of development caused either by environmental stress associated with the variation in water temperature, salinity, depth, feeding conditions and pollutants that have led to abnormalities in the development of individuals or by the presence of poor living conditions for the larvae resulting from unfavourable environments.

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Fancourt, Hayley S. M., Jeffrey J. Lynch, John E. Byrd e Carl N. Stephan. "Next‐generation osteometric sorting: Using 3D shape, elliptical Fourier analysis, and Hausdorff distance to optimize osteological pair‐matching". Journal of Forensic Sciences 66, n. 3 (6 febbraio 2021): 821–36. http://dx.doi.org/10.1111/1556-4029.14681.

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Hiremath, Rashmi B., e Ramesh M. Kagalkar. "Sign Language Video Processing for Text Detection in Hindi Language". International Journal of Recent Contributions from Engineering, Science & IT (iJES) 4, n. 3 (26 ottobre 2016): 21. http://dx.doi.org/10.3991/ijes.v4i3.5973.

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Abstract (sommario):

Sign language is a way of expressing yourself with your body language, where every bit of ones expressions, goals, or sentiments are conveyed by physical practices, for example, outward appearances, body stance, motions, eye movements, touch and the utilization of space. Non-verbal communication exists in both creatures and people, yet this article concentrates on elucidations of human non-verbal or sign language interpretation into Hindi textual expression. The proposed method of implementation utilizes the image processing methods and synthetic intelligence strategies to get the goal of sign video recognition. To carry out the proposed task implementation it uses image processing methods such as frame analysing based tracking, edge detection, wavelet transform, erosion, dilation, blur elimination, noise elimination, on training videos. It also uses elliptical Fourier descriptors called SIFT for shape feature extraction and most important part analysis for feature set optimization and reduction. For result analysis, this paper uses different category videos such as sign of weeks, months, relations etc. Database of extracted outcomes are compared with the video fed to the system as a input of the signer by a trained unclear inference system.

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Mahé, Kélig, Djamila Ider, Andrea Massaro, Oussama Hamed, Alba Jurado-Ruzafa, Patrícia Gonçalves, Aikaterini Anastasopoulou et al. "Directional bilateral asymmetry in otolith morphology may affect fish stock discrimination based on otolith shape analysis". ICES Journal of Marine Science 76, n. 1 (15 novembre 2018): 232–43. http://dx.doi.org/10.1093/icesjms/fsy163.

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Abstract (sommario):

Abstract Otolith shape analysis is an efficient fish stock identification tool. However, most applications used left and right otoliths or only one of them arbitrarily chosen without testing for biases resulting from potential directional bilateral asymmetry (DA) in otolith shape, i.e. a unimodal population-level deviation form bilateral symmetry between right and left otolith shapes. In this study, 560 bogues (Boops boops) were sampled from 11 geographical locations from the Canary Islands to the Aegean Sea and elliptical Fourier descriptors were used to describe their otoliths’ shape. First, a significant otolith DA was observed at the global scale with an average amplitude of 2.77%. However, at the scale of sampling locations, DA was not always significant and varied in amplitude and direction. Second, population structure was investigated using the shape of either right otoliths or left otoliths or both together. Analyses based on right otoliths or both otoliths together, suggested three stock units: a North-Western Mediterranean Sea stock, an Eastern Mediterranean Sea stock, and a Central-Eastern Atlantic Ocean and South-Western Mediterranean Sea stock. In contrast, no coherent geographical pattern was found based on left otoliths. Our results highlight the importance of accounting for potential otolith DA in otolith shape-based stock identification.

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Denechaud, Côme, Szymon Smoliński, Audrey J. Geffen e Jane A. Godiksen. "Long-term temporal stability of Northeast Arctic cod (Gadus morhua) otolith morphology". ICES Journal of Marine Science 77, n. 3 (29 febbraio 2020): 1043–54. http://dx.doi.org/10.1093/icesjms/fsz259.

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Abstract Otolith shape analysis provides a robust tool for the discrimination of many fish stocks in the context of fisheries management. However, there has been little research to examine within-stock temporal stability of otolith morphology in relation to changes in the environment and stock conditions. This study investigated the variability of Northeast Arctic (NEA) cod (Gadus morhua) otolith shape between 1933 and 2015, using elliptical Fourier descriptors extracted from archived material of 2968 mature fish. Series of hierarchical multivariate models were developed to relate shape to the identified optimal windows of some environmental drivers. Differences between years accounted for <3% of the observed variation and no significant differences were found between the average cohort shapes. The models not only confirmed that fish growth was the strongest driver of shape differences, but also highlighted effects of temperature and biomass-related variables at different life stages. Extrinsic factors described only a small fraction of the observed variance, which indicates that environmental changes over time likely account for less than the natural inter-individual variability in otolith shape. These results suggest that overall shape remains relatively stable through time within NEA cod, which further contributes towards a consensus on the biological interpretation of shape differences.

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Vörös, Fanni, Benjamin van Wyk de Vries, Marie-Noëlle Guilbaud, Tolga Görüm, Dávid Karátson e Balázs Székely. "DTM-Based Comparative Geomorphometric Analysis of Four Scoria Cone Areas—Suggestions for Additional Approaches". Remote Sensing 14, n. 23 (4 dicembre 2022): 6152. http://dx.doi.org/10.3390/rs14236152.

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Morphometric studies of scoria cones have a long history in research. Their geometry and shape are believed to be related to evolution by erosion after their formation, and hence the morphometric parameters are supposed to be related with age. We analysed 501 scoria cones of four volcanic fields: San Francisco Volcanic Field (Arizona, USA), Chaîne des Puys (France), Sierra Chichinautzin (Mexico), and Kula Volcanic Field (Turkey). All morphometric parameters (cone height, cone width, crater width, slope angles, ellipticity) were derived using DTMs. As new parameters, we calculated Polar Coordinate Transformed maps, Spatial Elliptical Fourier Descriptors to study the asymmetries. The age groups of the four volcanic fields were created and their slope distributions were analysed. The age groups of individual volcanic fields show a statistically significant decreasing tendency of slope angles tested by Mann–Whitney tests. By mixing the age groups of the volcanic fields and sorting them by age interval, we can also observe a general, statistically significant decrease. The interquartile ranges of the distributions also tend to decrease with time. These observations support the hypothesis that whereas the geometry of individual scoria cones differs initially (just after formation), general trends may exist for their morphological evolution with time in the various volcanic fields.

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Stransky, Christoph. "Geographic variation of golden redfish (Sebastes marinus) and deep-sea redfish (S. mentella) in the North Atlantic based on otolith shape analysis". ICES Journal of Marine Science 62, n. 8 (1 gennaio 2005): 1691–98. http://dx.doi.org/10.1016/j.icesjms.2005.05.012.

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Abstract The unresolved interrelationships of North Atlantic redfish stocks have prevented adaptive fisheries assessment and management in the past. Otolith shapes of golden redfish (S. marinus) and deep-sea redfish (S. mentella) were analysed for geographic variation within the entire distribution range in the North Atlantic, in order to evaluate this technique for stock separation. Multivariate analysis of elliptical Fourier shape descriptors revealed high similarity of S. marinus within the central North Atlantic areas (West and East Greenland, Iceland) that were relatively well separated from the Flemish Cap and Barents Sea samples. A similar separation of the Barents Sea area was also observed for S. mentella, whereas the western (Flemish Cap, Davis Strait) and central areas were overlapping to a greater extent. The overall classification rate given by discriminant analysis was poor for both species (<50%) but increased to 72–74% by combining sampling areas to regions (west, central, east). Geographic variation in otolith shapes of both redfish species suggests a separation of the Northeast Arctic stocks (Barents Sea) of both species from the other redfish stocks assessed within ICES and NAFO, whereas similarities observed for the highly migratory S. mentella give reason for integrated management of demersal and pelagic occurrences of this important fisheries resource that straddles the ICES/NAFO boundaries.

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Leguá, Javier, Guido Plaza, Darío Pérez e Alexander Arkhipkin. "Otolith shape analysis as a tool for stock identification of the southern blue whiting, Micromesistius australis". Latin American Journal of Aquatic Research 41, n. 3 (7 marzo 2017): 479–89. http://dx.doi.org/10.3856/vol41-issue3-fulltext-11.

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Abstract (sommario):

The southern blue whiting, Micromesistius australis (Norman, 1937), is an important demersal resource associated with the slope and continental shelf of southern Chile, Argentina and the Malvinas/Falkland Islands. Recent studies have reported schools of adult fish from Atlantic waters migrating along the southern Chilean coast in mid-winter, moving northwards to spawn in August (47º-51ºS), and then returning to Atlantic waters, presumably to feed. The migratory pattern suggests the presence of one or more stock units associated with the South American coast. In the present study, “otolith morphometry” is used to determine the stock structure of M. australis based on applications of basic size descriptors (SDs) (area, perimeter and otolith size), shape indices (SIs) (circularity, squareness, shape factor, roundness, ellipticity), and normalised elliptical Fourier descriptors (NEFDs). Samples were collected during the winter and spring of 2010, during the reproductive period, in the economic zone of southern Chile (36º-57ºS), in the Pacific Ocean and around the Falkland Islands economic zone (50º-52ºS) in the Atlantic Ocean. Analyses were conducted to include the effects of size, sex and age. A stepwise canonical discriminant analysis showed that fish were successfully discriminated with SDs, SIs and NEFDs. In this analysis, 86.4% and 70.1% of the fish were correctly classified as belonging to the Atlantic and Pacific stocks, respectively. A multivariate analysis of variance showed that the mean values of the NEFDs, SDs, and SIs did not vary significantly between sexes within areas (P > 0.05), but varied significantly between the Pacific and Atlantic oceans (P < 0.05). These results highlighted that otolith shape analysis can be a useful tool to evaluate the potential level of mixing in feeding areas where both stocks, the Pacific and Atlantic units, are expected to co-occur.

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Tao, Yongpeng, Yu Jing e Cong Xu. "Target Recognition in SAR Image by Joint Classification of Target Region and Shadow". Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) 12, n. 4 (23 agosto 2019): 347–54. http://dx.doi.org/10.2174/2352096511666180727110642.

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Background: A synthetic aperture radar (SAR) automatic target recognition (ATR) method is proposed in this paper via the joint classification of the target region and shadow. Methods: The elliptical Fourier descriptors (EFDs) are used to describe the target region and shadow extracted from the original SAR image. In addition, the relative positions between the target region and shadow are represented by a constructed feature vector. The three feature vectors complement each other to provide more comprehensive descriptions of the target’s physical properties, e.g., sizes and shape. In the classification stage, the three feature vectors are jointly classified based on the joint sparse representation (JSR). JSR is a multi-task learning algorithm, which can not only represent each component properly but also exploit the inner correlations of different components. Finally, the target type is determined to the class with the minimum reconstruction error. Results: Experiments have been conducted on the Moving and Stationary Target Acquisition and Recognition (MSTAR) dataset. The proposed method achieves a high recognition accuracy of 96.86% for 10-class recognition problem under the standard operating condition (SOC). Moreover, robustness of the proposed method is also superior over the reference methods under the extended operating conditions (EOCs) like configuration variance, depression angle variance, and noise corruption. Conclusion: Therefore, the effectiveness and robustness of the proposed method can be quantitatively demonstrated by the experimental results.

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Mahé, Kélig, Kirsteen MacKenzie, Djamila Ider, Andrea Massaro, Oussama Hamed, Alba Jurado-Ruzafa, Patrícia Gonçalves et al. "Directional Bilateral Asymmetry in Fish Otolith: A Potential Tool to Evaluate Stock Boundaries?" Symmetry 13, n. 6 (1 giugno 2021): 987. http://dx.doi.org/10.3390/sym13060987.

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Abstract (sommario):

The otolith, found in both inner ears of bony fish, has mainly been used to estimate fish age. Another application that has been developing significantly in recent years, however, is the use of otolith shape as a tool for stock identification. Often, studies have directly used the shape asymmetry between the right and left otoliths. We tested the magnitude of directional asymmetry between the sagittal otoliths (left vs. right) of 2991 individuals according to their catch locations, and we selected species to evaluate whether directional asymmetry may itself be a tool to evaluate stock boundaries. Elliptical Fourier descriptors were used to describe the otolith shape. We used a flatfish, the common sole (Solea solea, n = 2431), from the eastern English Channel and the southern North Sea as well as a roundfish, the bogue (Boops boops, n = 560), from the Mediterranean Sea. Both species showed significant levels of directional asymmetry between the testing locations. The bogue otoliths showed significant asymmetry for only 5 out of 11 locations, with substantial separation between two large areas: the Algerian coast and the western part of the Italian coast. The sole otoliths showed significant asymmetry in the shape analysis (3.84%–6.57%), suggesting a substantial separation between two large areas: the English and French parts of the English Channel and the southern North Sea. Consequently, directional bilateral asymmetry in otolith shape is a potential new method for stock identification.

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Liang, Guanglin, Linchong Huang e Chengyong Cao. "Analysis and Prediction of Grouting Reinforcement Performance of Broken Rock Considering Joint Morphology Characteristics". Mathematics 13, n. 2 (15 gennaio 2025): 264. https://doi.org/10.3390/math13020264.

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In tunnel engineering, joint shear slip caused by external disturbances is a key factor contributing to landslides, instability of surrounding rock masses, and related hazards. Therefore, accurately characterizing the macromechanical properties of joints is essential for ensuring engineering safety. Given the significant influence of rock joint morphology on mechanical behavior, this study employs the frequency spectrum fractal dimension (D) and the frequency domain amplitude integral (Rq) as quantitative descriptors of joint morphology. Using Fourier transform techniques, a reconstruction method is developed to model joints with arbitrary shape characteristics. The numerical model is calibrated through 3D printing and direct shear tests. Systematic parameter analysis validates the selected quantitative indices as effective descriptors of joint morphology. Furthermore, multiple machine learning algorithms are employed to construct a robust predictive model. Machine learning, recognized as a rapidly advancing field, plays a pivotal role in data-driven engineering applications due to its powerful analytical capabilities. In this study, six algorithms—Random Forest (RF), Support Vector Regression (SVR), BP Neural Network, GA-BP Neural Network, Genetic Programming (GP), and ANN-based MCD—are evaluated using 300 samples. The performance of each algorithm is assessed through comparative analysis of their predictive accuracy based on correlation coefficients. The results demonstrate that all six algorithms achieve satisfactory predictive performance. Notably, the Random Forest (RF) algorithm excels in rapid and accurate predictions when handling similar training data, while the ANN-based MCD algorithm consistently delivers stable and precise results across diverse datasets.

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Zhao, Jianhui, Zhong Zhang, Shizhong Han, Chengzhang Qu, Zhiyong Yuan e Dengyi Zhang. "SVM based forest fire detection using static and dynamic features". Computer Science and Information Systems 8, n. 3 (2011): 821–41. http://dx.doi.org/10.2298/csis101012030z.

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A novel approach is proposed in this paper for automatic forest fire detection from video. Based on 3D point cloud of the collected sample fire pixels, Gaussian mixture model is built and helps segment some possible flame regions in single image. Then the new specific flame pattern is defined for forest, and three types of fire colors are labeled accordingly. With 11 static features including color distributions, texture parameters and shape roundness, the static SVM classifier is trained and filters the segmented results. Using defined overlapping degree and varying degree, the remained candidate regions are matched among consecutive frames. Subsequently the variations of color, texture, roundness, area, contour are computed, then the average and the mean square deviation of them are obtained. Together with the flickering frequency from temporal wavelet based Fourier descriptors analysis of flame contour, 27 dynamic features are used to train the dynamic SVM classifier, which is applied for final decision. Our approach has been tested with dozens of video clips, and it can detect forest fire while recognize the fire like objects, such as red house, bright light and flying flag. Except for the acceptable accuracy, our detection algorithm performs in real time, which proves its value for computer vision based forest fire surveillance.

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ZVONAREVA, Sofia S., Yury V. DEART, Fedor LISCHENKO, H. T. Yen DINH, T. Tu Nguyen e Elena MEKHOVA. "Shell shape variation of the symbiotic gastropod Phenacovolva rosea in Vietnam". Ruthenica, Russian Malacological Journal 34, n. 3 (1 luglio 2024): 99–109. http://dx.doi.org/10.35885/ruthenica.2024.34(3).1.

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Abstract (sommario):

This study investigates the shell variability of Phenacovolva rosea, a symbiotic gastropod inhabiting octocorals, in relation to geographical location and host coral species. We analyzed shells from 53 adult specimens collected at three locations in the north of Vietnam and one in the vicinities of Nha Trang City (southern Vietnam). To describe the shells' outlines, elliptical Fourier descriptors were applied. Based on the shell outline data, principal component analysis was performed. Additionally, height and width of P. rosea shells were measured. Only the first two principal components were effective, with the first principal component accounting for 92.8% of the variation. It closely correlated with width-to-height ratio of shells. According to dispersion analysis (ANOVA), shells in Nha Trang were significantly slimmer with longer terminal processes compared to those from the three northern locations. The coral host species also impacted shell shape when considering the entire dataset. However, this difference may have stemmed from shell variations between locations, as coral composition is not independent of location. When regional samples were analyzed separately, no significant impact of the host was detected. The factors that differed between northern locations and Nha Trang were then discussed, along with the mechanisms underlying their influence. We suggest that predation risk, influenced by water turbidity, is greater in the clearer waters of Nha Trang. This increased predator pressure may explain the presence of long terminals on P. rosea shells found in Nha Trang, potentially providing protection against some fish predators. Furthermore, the shorter and wider shells found in northern locations may be advantageous in waters with higher current speeds, whereas the long-teminal shells with narrow apertures observed in Nha Trang may be better suited for slower currents. The climate disparity, encompassing temperature and salinity mediated through precipitation, could also potentially influence shell morphology. However, the underlying mechanism remains unclear due to the complex nature of these interactions and the scarcity of literature data. Isolating host-specific shell shape traits from other factors proved challenging, given the close association between host species composition and location. Laboratory experiments modeling each factor independently may provide a solution to this issue.

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Robot, Rianto, Joudy R. R. Sangari e Boyke H. Toloh. "Avicennia marina Leaf Morphometric Digital Data Visualization In Tongkaina And Bintauna Coastal Areas". JURNAL ILMIAH PLATAX 6, n. 1 (1 novembre 2017): 42. http://dx.doi.org/10.35800/jip.6.1.2018.17878.

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The development of biology has been a major step in explaining variations in form. Information on the morphometric characteristics of A. marina leaves can be collected, managed, calculated and displayed visually using the current emerging technologies. The emerging technology is image processing software. In this study, the leaf identification was performed automatically on digital image data to measure variations and make morphometrics leaf digitalization using the software. Measurement and visualization on the morphometric s of the shape based on digital image data is still rare. To know the comparison of morphometric characters of leaf based on location difference, the research was done by comparing morphometric of A. marina leaves in Bintauna and Tongkaina using digital image processing technology and object analysis. A. marina leaf samples were collected and imaged with the camera. Furthermore, the image is processed with ImageJ to obtain the results of morphometric character and leaf landmark data. The results of the length ratio and width of the leaf were tested by t test, while the landmark data was visualized with PAST software. Image data also analyzed and visualized using elliptic Fourier descriptors (EFDs) method, plus visualization of the size and overall shape of leaf contours using Photoshop. The results showed that the size of A. marina leaves in Tongkaina are greater than that of Bintauna. A. marina leaves at Tongkaina have a length of 65,36 mm, width 36,02 mm, wide by 169,24 mm2 and circle 178,78 mm, While in Bintauna have a length of 63,76 mm, width 31,82 mm, width 149.63 mm2 and circle 166.50 mm. Visualization applied directly on A. marina leaf shape using the technique of point of coordinates of leaf (landmark) and leaf edge contour detection technique using Photoshop, the result of a whole analysis indicates that A. marina leaves in Tongkaina have symmetrical mean (morphometric) which is slightly different than those in Bintauna. Based on the result of EFDs method calculation and statistical t test, the result shows that leaf size of both populations of A. marina in Tongkaina and Bintauna has no difference.Keywords: Digital Imagery, Visualization, Morphometrics, Avicennia marina, Bintauna, TongkainaABSTRAKPerkembangan biologi telah menjadi langkah besar dalam menjelaskan variasi bentuk. Informasi mengenai data karakteristik morfometrik daun A. marina dapat dikumpulkan, dikelola dan dihitung serta ditampilkan secara visual menggunakan teknologi yang berkembang saat ini. Teknologi yang sedang berkembang adalah perangkat lunak pengolah gambar. Identifikasi daun dapat dilakukan secara otomatis pada data citra digital untuk mengukur variasi dan membuat digitalisasi morfometrik daun menggunakan perangkat lunak.Pengukuran dan penggambaran (visualisasi) mengenai bentuk morfometrik berdasarkan data citra digital masih belum banyak dilakukan. Untuk mengetahui perbandingan karakteristik morfometrik daun berdasarkan perbedaan lokasi, dilakukan penelitian dengan membandingkan morfometrik daun A. marina yang ada di Bintauna dan Tongkaina menggunakan teknologi digital image processing dan analisis objek untuk melakukan visualisasi data. Sampel daun A. marina dikumpulkan dan dicitrakan dengan kamera. Selanjutnya citra diproses dengan ImageJ untuk mendapatkan hasil pengukuran karakter morfometrik dan data landmark daun. Hasil pengukuran rasio panjang dan lebar daun diuji dengan uji t, sedangkan data landmark divisualisasi dengan perangkat lunak PAST. Data citra juga dianalisis dan divisualisasi dengan metode elliptical fourier descriptors (EFDs), ditambah dengan visualisasi ukuran dan bentuk keseluruhan dari kontur daun menggunakan Photoshop. Hasil penelitian menunjukan bahwa ukuran daun A. marina yang ada di Tongkaina lebih besar dibandingkan dengan yang ada di Bintauna. Daun A. marina di Tongkaina memiliki ukuran panjang 65,36 mm, lebar 36,02 mm, luas 169,24 mm2 dan lingkaran 178,78 mm, Sedangkan di Bintauna memiliki ukuran panjang 63,76 mm, lebar 31,82 mm, luas 149,63 mm2 dan lingkaran 166,50 mm. Visualisasi secara langsung dari bentuk daun A. marina dengan teknik menggunakan titik koordinat daun (landmark) serta menggunakan teknik pendeteksian tepi bentuk kontur daun menggunakan Photoshop, hasil analisis keseluruhan menunjukan bahwa daun A. marina yang ada di Tongkaina memiliki bentuk rata-rata kesimetrisan (morfometrik) yang sedikit berbeda dibandingkan dengan yang berada di Bintauna. Berdasarkan hasil uji statistik dengan metode (EFDs) kemudian dilanjutkan dengan uji t, menunjukan hasil bahwa ukuran daun kedua populasi A. marina yang di Tongkaina dan Bintauna adalah tidak berbeda.Kata kunci : Citra digital, Visualisasi, Morfometrik, Avicennia marina, Bintauna, Tongkaina

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"CHOG Based EFD for Geometric Shape Retrieval of Images for Cloth and Object Invariant Gait Recognition". International Journal of Recent Technology and Engineering 8, n. 4 (30 novembre 2019): 11887–92. http://dx.doi.org/10.35940/ijrte.d9597.118419.

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Abstract (sommario):

Gait refers to person identification based on the observation of human walking style. One of the prominent hurdles in gait recognition is, the challenges posed by change in apparels like clothes and object held by the subject. The paper explores the feature extraction techniques like CHOG and Elliptical Fourier Descriptors in spatial and frequency domain respectively to mitigate this negative impact on gait recognition. The CHOG behavioural feature extraction technique is used to capture the effective distribution of local gradient on gait sequence images. Further the Elliptical Fourier Descriptor (EFD) is found in frequency domain to access the geometric characteristics of a spatial domain image. The work is carried out on 36 subjects with 5 different apparels and 3 different objects each with 6 gait cycles from standard dataset CASIA SET – B and CMU - MoBo. SVM classifier is used to effectively discriminate the gait cycle patterns using optimal hyper plane. The results obtained have given an improvement of 7% to 24% increase in gait recognition over earlier techniques like GEI, CDA, LDA, ENTROPY, static and dynamic region splitting.

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48

Chang, Yuan, Jia-Ling Chang e Jyh-Jone Lee. "Path synthesis of planar four-bar linkages for closed and open curves using elliptical Fourier descriptors". Journal of Mechanical Science and Technology, 3 maggio 2024. http://dx.doi.org/10.1007/s12206-024-0436-y.

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49

Muro, Satoru, Jiyoon Kim, Akimoto Nimura, Sachiyuki Tsukada e Keiichi Akita. "Morphometric Analysis of the Tibial Attachment Shape of the Anterior Cruciate Ligament and Its Relationship With the Location of the Anterior Horn of the Lateral Meniscus". American Journal of Sports Medicine, 29 gennaio 2024. http://dx.doi.org/10.1177/03635465231219978.

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Abstract (sommario):

Background: The success of anterior cruciate ligament (ACL) reconstruction relies on the accurate replication of the native ACL anatomy, including attachment shapes. The tibial attachment of the ACL exhibits significant shape variations with elliptical, C, and triangular shapes, highlighting the need for objective classification methods and additional information to identify individual anatomic variations. Hypothesis: The location of the attachment of the anterior horn of the lateral meniscus (AHLM) may determine the shape of the ACL attachment. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The study used 25 knees from 17 Japanese cadavers for macroscopic anatomic examination and quantitative analysis. The shape of the ACL attachment was quantified using principal component analysis with elliptical Fourier descriptors, whereas the AHLM location was quantified by measuring its mediolateral and anteroposterior positions on the superior surface of the tibia. Reliability was assessed statistically. Results: The shape of the tibial attachment of the ACL varied among individuals and was classified as elliptical, C-shaped, or triangular. Scatterplots of the principal components of the ACL attachment shape showed overlapping regions of elliptical, C-shaped, and triangular ACL attachments, indicating that a C-shaped attachment is intermediate between elliptical and triangular attachments. The location of the AHLM attachment also varied, with areas in the anterolateral, anteromedial, or posteromedial region. The ACL shape and AHLM location were related, with elliptical, C-shaped, and triangular ACL attachments corresponding to anterolateral, anteromedial, and posteromedial AHLM attachments, respectively. Conclusion: The AHLM attachment location influences the shape of the ACL attachment. Information on the location of the AHLM attachment can aid in predicting the shape of the ACL attachment during ACL reconstruction, potentially improving footprint coverage.

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Zhang, Yanhuan, Shangqu Sun, Jing Wang, Liping Li, Zizheng Sun, Diyang Chen e Yanqing Men. "A New Method for Determining the Safety Distance Between Irregular Karst Cave and Circumferential Shield Tunnel". International Journal for Numerical and Analytical Methods in Geomechanics, 20 ottobre 2024. http://dx.doi.org/10.1002/nag.3869.

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Abstract (sommario):

ABSTRACTWhen a shield tunnel passes through a karst area, the water‐filled cave can easily make the surrounding rock metamorphic, resulting in water inrush, ground collapse, and shield machine failure and other engineering hazards. Natural cavities have a significant degree of geometric irregularity due to groundwater alteration and soluble rock erosion. Considering the difficulties in describing the shape of a natural irregular cavity, circular, rectangular, and elliptical geometries have been simplified in most related studies. Based on the upper bound theorem of limit analysis, we established a three‐dimensional failure model including the karst caves located directly above and below the circumferential side of the tunnel. Then, we deduced the corresponding analytical solution of the critical safety distance (CSD). Furthermore, the effects of rock mass parameters, cave parameters, and geometric parameters on the CSD were analyzed. Then we designed the numerical simulation considering the irregular geometry shape at the circumferential side of tunnel using the Fourier descriptors. In addition, we estimated the CSDs for two failure models using the revised dichotomy and failure criterion. The findings demonstrated a quantifiable association between CSD and Fourier descriptors of irregular cave shape, resulting in the development of a CSD prediction model. These test results can provide a theoretical foundation and direction for predicting water inrush caused by the constrained irregular cave.

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