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Journal articles on the topic 'Matrice de corde'

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Published: 4 June 2021
Last updated: 1 February 2022

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1

Yaguchi, Yoshiro. "Matrices and diagrams of cords on a punctured plane." Journal of Knot Theory and Its Ramifications 27, no. 05 (April 2018): 1850036. http://dx.doi.org/10.1142/s0218216518500360.

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A cord is a simple curve on a punctured plane. We introduce diagrams which represent isotopy classes of cords. Using such diagrams, we prove that there is a one-to-one correspondence from the set of the isotopy classes of cords to a set of symmetric matrices whose components are non-negative integers, and we give necessary conditions for matrices to represent the isotopy classes of cords.
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2

Marchand, R., and S. Woerly. "Transected spinal cords grafted with in situ self-assembled collagen matrices." Neuroscience 36, no. 1 (January 1990): 45–60. http://dx.doi.org/10.1016/0306-4522(90)90350-d.

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3

Talacchia, S., J. Amador, and J. Urcola. "Fabricación de matrices de corte con aceros rápidos para herramientas mediante metalurgia de polvos." Revista de Metalurgia 32, no. 1 (February 28, 1996): 18–24. http://dx.doi.org/10.3989/revmetalm.1996.v32.i1.927.

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4

Horn, Eric M., Michael Beaumont, Xiao Zheng Shu, Adrian Harvey, Glenn D. Prestwich, Kris M. Horn, Alan R. Gibson, Mark C. Preul, and Alyssa Panitch. "Influence of cross-linked hyaluronic acid hydrogels on neurite outgrowth and recovery from spinal cord injury." Journal of Neurosurgery: Spine 6, no. 2 (February 2007): 133–40. http://dx.doi.org/10.3171/spi.2007.6.2.133.

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Object Therapies that use bioactive materials as replacement extracellular matrices may hold the potential to mitigate the inhibition of regeneration observed after central nervous system trauma. Hyaluronic acid (HA), a nonsulfated glycosaminoglycan ubiquitous in all tissues, was investigated as a potential neural tissue engineering matrix. Methods Chick dorsal root ganglia were cultured in 3D hydrogel matrices composed of cross-linked thiol-modified HA or fibrin. Samples were cultured and images were acquired at 48-, 60-, and 192-hour time points. Images of all samples were analyzed at 48 hours of incubation to quantify the extent of neurite growth. Cultures in cross-linked thiolated HA exhibited more than a 50% increase in neurite length compared with fibrin samples. Furthermore, cross-linked thiolated HA supported neurites for the entire duration of the culture period, whereas fibrin cultures exhibited collapsed and degenerating extensions beyond 60 hours. Two concentrations of the thiolated HA (0.5 and 1%) were then placed at the site of a complete thoracic spinal cord transection in rats. The ability of the polymer to promote regeneration was tested using motor evoked potentials, retrograde axonal labeling, and behavioral assessments. There were no differences in any of the parameters between rats treated with the polymer and controls. Conclusions The use of a cross-linked HA scaffold promoted robust neurite outgrowth. Although there was no benefit from the polymer in a rodent spinal cord injury model, the findings in this study represent an early step in the development of semisynthetic extracellular matrice scaffolds for the treatment of neuronal injury.
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Marada, Tomas, Radomil Matousek, and Daniel Zuth. "Design of Linear Quadratic Regulator (LQR) Based on Genetic Algorithm for Inverted Pendulum." MENDEL 23, no. 1 (June 1, 2017): 149–56. http://dx.doi.org/10.13164/mendel.2017.1.149.

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One of the crucial problems in the dynamics and automatic control theory is balancing of an invertedpendulum robot by moving a cart along a horizontal path. This task is often used as a benchmark for di erentmethod comparison. In the practical use of the LQR method, the key problem is how to choose weight matricesQ and R correctly. To obtain satisfying results the experiments should be repeated many times with di erentparameters of weight matrices. These LQR parameters can be tuned by a Genetic Algorithm (GA) techniquefor getting better results. In our paper, the LQR parameters weight matrices Q and R which were tuned usingthe Genetic Algorithm. The simulations of the control problem are designed using MATLAB script code andMATLAB Simulink on an inverted pendulum model. The results show that the Genetic Algorithm is suitablefor tuning the parameters to give an optimal response. The control problem of the inverted pendulum was solvedsuccessfully.
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6

Moreira-Mendoza, Néstor, and Grether Real-Pérez. "Tiempo estándar en gestión de mantenimiento de matrices de corte." Revista Científica INGENIAR: Ingeniería, Tecnología e Investigación 4, no. 8 Edicion especial septiembre (September 15, 2021): 2–29. http://dx.doi.org/10.46296/ig.v4i8edespsep.0027.

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El estudio de tiempos es una técnica de mejora continua utilizada para mitigar problemas de procesos de producción y reducción de tiempos. Los tiempos de reparación de las matrices de corte han acentuado una problemática en los procesos industriales, afectando a la organización del mantenimiento. El propósito de esta investigación es identificar, evaluar y estandarizar los tiempos de reparación de las matrices de corte de la fábrica manufacturera “Arte Mueble”. Como técnica metodológica se optará por realizar pruebas de campo para constatar el estado actual del proceso de reparación de las matrices de corte, así como la de recolección de datos en la identificación de factores incidente en los tiempos de reparación, así como el cronometraje y análisis para establecer el tiempo estándar. Resultados esperados: El análisis del proceso de mantenimiento, determinará la eficiencia en el mismo, presentando tiempos reales utilizados, así como características del entorno de operación y factores externos incidentes del proceso; el tiempo estándar mostraría las causas de retrasos significativos, factores externos y estrategia de mitigación de los mismos, capacitación del personal técnico y calificación del mismo. Investigación que detecta la problemática y los factores que inciden en los tiempos de reparación de las matrices de corte, estandarización de tiempos como técnica efectiva en la mejora del proceso de mantenimiento, hecho que deja puertas abiertas para que la organización del mantenimiento considere la metodología y contribuyan a la mejora de la eficiencia del mantenimiento. Palabras clave: Eficiencia, Estandarización, Organización, Mantenimiento, Matrices de corte.
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7

Fan, Jun, Yang Xiao, and Kiseon Kim. "Design LDPC Codes without Cycles of Length 4 and 6." Research Letters in Communications 2008 (2008): 1–5. http://dx.doi.org/10.1155/2008/354137.

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We present an approach for constructing LDPC codes without cycles of length 4 and 6. Firstly, we design 3 submatrices with different shifting functions given by the proposed schemes, then combine them into the matrix specified by the proposed approach, and, finally, expand the matrix into a desired parity-check matrix using identity matrices and cyclic shift matrices of the identity matrices. The simulation result in AWGN channel verifies that the BER of the proposed code is close to those of Mackay's random codes and Tanner's QC codes, and the good BER performance of the proposed can remain at high code rates.
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8

Richeson, M., U. Erturun, R. Waxman, K. Mossi, T. Suzuki, J. Kunikata, and H. Asanuma. "J0404-8-6 Characterization of a Pt-core PZT Fiber/Al Matrix Composite." Proceedings of the JSME annual meeting 2010.6 (2010): 345–46. http://dx.doi.org/10.1299/jsmemecjo.2010.6.0_345.

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9

Rabin, A. V., S. V. Michurin, and V. A. Lipatnikov. "DEVELOPMENT OF A CLASS OF SYSTEM AND RETURN SYSTEM MATRIXES PROVIDING INCREASE IN NOISE IMMUNITY OF SPECTRALLY EFFECTIVE MODULATION SCHEMES ON BASIS OF ORTHOGONAL CODING." Issues of radio electronics, no. 10 (October 20, 2018): 75–79. http://dx.doi.org/10.21778/2218-5453-2018-10-75-79.

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In work it is proposed in the digital systems of messages transmission for noise immunity's increase with the fixed code rate to use an additional coding called by the authors orthogonal. The way of a definition of orthogonal codes is presented, the synthesis algorithm of system and inverse system matrices of orthogonal codes is developed, and the main parameters of some matrices constructed by the offered algorithm are specified. Orthogonal coding as a special case of convolutional coding is defined by matrices, which elements are polynomials in the delay variable with integer coefficients. Code words are given by multiplication of an information polynomial by a system matrix, and decoding is performed by multiplication by an inverse system matrix. Basic ratios for orthogonal coding are given in article, and properties of system and inverse matrices are specified. Parameters of system and inverse system matrices assure additional gain in signal-to-noise ratio. This gain is got as a result of a more effective use of energy of transmitted signals. For transmission of one symbol energy of several symbols is accumulated.
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10

MURILLO, GABRIEL, SAM NELSON, and ANTHONY THOMPSON. "MATRICES AND FINITE ALEXANDER QUANDLES." Journal of Knot Theory and Its Ramifications 16, no. 06 (August 2007): 769–78. http://dx.doi.org/10.1142/s0218216507005488.

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We study the question of whether a finite quandle specified by a matrix is isomorphic to an Alexander quandle. We first collect some necessary conditions for a finite quandle to be Alexander. We then describe an algorithm for determining finding all possible Alexander presentations of a finite quandle given its matrix and provide a URL for Maple code implementing this algorithm.
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11

Farkaš, Peter, and Frank Schindler. "Run length limited error control codes construction based on one control matrix property." Journal of Electrical Engineering 68, no. 4 (August 28, 2017): 322–24. http://dx.doi.org/10.1515/jee-2017-0046.

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AbstractIn this manuscript a simple method is presented for constructing run length limited error control codes from linear binary block codes. The run length limited properties are obtained via addition of a carefully chosen fixed binary vector - a modifier to all codewords without introducing any additional redundancy. Modifier selection is based on a specific property, which can be found in some of the linear binary block codes control matrices. Similar known methods are based on properties of generator matrices. However some codes are specified via control matrices, for example low density parity check codes. The method proposed in this letter could be applied to some of them directly. This is illustrated in this manuscript using example in which a run length limited low density parity check code is obtained from Gallager code.
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12

Martínez Aneiro, Federico, and Teresa Sánchez Battaille. "Altas velocidades de corte, aplicadas a la fabricación en moldes y matrices." Informador Técnico 71 (December 14, 2007): 12. http://dx.doi.org/10.23850/22565035.775.

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La demanda de componentes mecánicos de alta calidad y gran exactitud para sistemas de elevada precisión está aumentando considerablemente en los últimos años a nivel mundial; este hecho ha provocado el desarrollo de nuevas tecnologías aplicadas a los procesos de corte. El desarrollo de las máquinas herramientas, las herramientas de corte y de la tecnología de maquinado posibilitó la aplicación del corte con altas velocidades de corte (High Speed Cutting HSC). El aumento de las velocidades de corte es una de las formas de incrementar la eficiencia de los procesos productivos a través de Ia reducción de los tiempos de fabricación y sustitución o minimización de otros procesos de elaboración que forman parte de Ia cadena productiva. Por ser un proceso relativamente nuevo, apenas desde los años 90 es que se implementa la introducción del HSC y muchas cuestiones tecnológicas que aún se están investigando. Por otro lado, las características ya conocidas de esta nueva tecnología indican una buena perspectiva de aplicación en los más diversos segmentos de la industria sobre todo en la de moldes y matrices.
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13

Timakul, Sekson, and Somsak Choomchuay. "A Construction of Non Binary LDPC Codes by Circular Matrices." Advanced Materials Research 909 (March 2014): 338–41. http://dx.doi.org/10.4028/www.scientific.net/amr.909.338.

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In LDPC code, the structure of code's parity check matrix plays the crucial role in code performance. In this paper proposes the preliminary investigation of a designed parity check matrix from Tanner. We modify this technique in to non binary LDPC structure and decoding with FFT-SPA. We take into high code rate application more than 0.8. The result has shown that in bit error rate (BER) compare between non-binary LDPC and binary LDPC. In our results, the performance of non binary LDPC has better than binary LDPC.
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14

HE, MATTHEW, and SERGEY PETOUKHOV. "THE GENETIC CODE, HADAMARD MATRICES AND ALGEBRAIC BIOLOGY." Journal of Biological Systems 18, spec01 (October 2010): 159–75. http://dx.doi.org/10.1142/s0218339010003688.

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Algebraic theory of coding is one of modern fields of applications of algebra. This theory uses matrix algebra intensively. This paper is devoted to an application of Kronecker's matrix forms of presentations of the genetic code for algebraic analysis of a basic scheme of degeneracy of the genetic code. Similar matrix forms are utilized in the theory of signal processing and encoding. The Kronecker family of the genetic matrices is investigated, which is based on the genetic matrix [C A; U G], where C, A, U, G are the letters of the genetic alphabet. This matrix in the third Kronecker power is the (8*8)-matrix, which contains all 64 genetic triplets in a strict order with a natural binary numeration of the triplets by numbers from 0 to 63. Peculiarities of the basic scheme of degeneracy of the genetic code are reflected in the symmetrical black-and-white mosaic of this genetic (8*8)-matrix. This mosaic matrix is connected algorithmically with Hadamard matrices unexpectedly, which are famous in the theory of signal processing and encoding, spectral analysis, quantum mechanics and quantum computers. Furthermore, many kinds of cyclic permutations of genetic elements lead to reconstruction of initial Hadamard matrices into new Hadamard matrices unexpectedly. This demonstrates that matrix algebra is one of promising instruments and of adequate languages in bioinformatics and algebraic biology.
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15

Maziero, Jonas. "Computing Coherence Vectors and Correlation Matrices with Application to Quantum Discord Quantification." Advances in Mathematical Physics 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/6892178.

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Coherence vectors and correlation matrices are important functions frequently used in physics. The numerical calculation of these functions directly from their definitions, which involves Kronecker products and matrix multiplications, may seem to be a reasonable option. Notwithstanding, as we demonstrate in this paper, some algebraic manipulations before programming can reduce considerably their computational complexity. Besides, we provide Fortran code to generate generalized Gell-Mann matrices and to compute the optimized and unoptimized versions of associated Bloch’s vectors and correlation matrix in the case of bipartite quantum systems. As a code test and application example, we consider the calculation of Hilbert-Schmidt quantum discords.
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16

Nguyen, Duc Manh, and Sunghwan Kim. "New construction of binary and nonbinary quantum stabilizer codes based on symmetric matrices." International Journal of Modern Physics B 33, no. 24 (September 30, 2019): 1950274. http://dx.doi.org/10.1142/s0217979219502746.

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In this paper, we propose two construction methods for binary and nonbinary quantum stabilizer codes based on symmetric matrices. In the first construction, we use the identity and symmetric matrices to generate parity-check matrices that satisfy the symplectic inner product (SIP) for the construction of quantum stabilizer codes. In the second construction, we modify the first construction to generate parity-check matrices based on the Calderbank–Shor–Stean structure for the construction of quantum stabilizer codes. The binary and nonbinary quantum stabilizer codes whose parameters achieve equality of the quantum singleton bound are investigated with the code lengths ranging from 4 to 12.
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17

Starek, L., D. J. Inman, and A. Kress. "A Symmetric Inverse Vibration Problem." Journal of Vibration and Acoustics 114, no. 4 (October 1, 1992): 564–68. http://dx.doi.org/10.1115/1.2930299.

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This paper considers the inverse eigenvalue problem for linear vibrating systems described by a vector differential equation with constant coefficient matrices. The inverse problem of interest here is that of determining real symmetric coefficient matrices, assumed to represent the mass, damping, and stiffness matrices, given the natural frequencies and damping ratios of the structure (i.e., the system eigenvalues). The approach presented here allows for repeated eigenvalues, whether simple or not, and for rigid body modes. The method is algorithmic and results in a computer code for determining mass normalized damping, and stiffness matrices for the case that each mode of the system is underdamped.
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18

Rapo, Marja Liisa, Jukka Aho, Hannu Koivurova, and Tero Frondelius. "Implementing model reduction to the JuliaFEM platform." Rakenteiden Mekaniikka 51, no. 1 (August 16, 2018): 36–54. http://dx.doi.org/10.23998/rm.69026.

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JuliaFEM is an open source finite element method solver written in the Julia language. This paper presents an implementation of two common model reduction methods: the Guyan reduction and the Craig-Bampton method. The goal was to implement these algorithms to the JuliaFEM platform and demonstrate that the code works correctly. This paper first describes the JuliaFEM concept briefly after which it presents the theory of model reduction, and finally, it demonstrates the implemented functions in an example model. This paper includes instructions for using the implemented algorithms, and reference the code itself in GitHub. The reduced stiness and mass matrices give the same results in both static and dynamic analyses as the original matrices, which proves that the code works correctly. The code runs smoothly on relatively large model of 12.6 million degrees of freedom. In future, damping could be included in the dynamic condensation now that it has been shown to work.
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19

Mironov, S. "From a reversible code to the quantum one: R-matrix." EPJ Web of Conferences 182 (2018): 02088. http://dx.doi.org/10.1051/epjconf/201818202088.

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This research has been carried out in collaboration with D.Melnikov, A.Mironov, A.Morozov and An.Morozov. We study the relation between quantum programming and knot theory. The general idea is that knot theory provides a special basis for unitary matrices. We suggest to use R-matrices of knot theory as universal gates in quantum code. We also examine basic operations in reversible programming.
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Çalışkan, Basri, and Kemal Balıkçı. "Counting Z2 Z4 Z8-additive Codes." European Journal of Pure and Applied Mathematics 12, no. 2 (April 29, 2019): 668–79. http://dx.doi.org/10.29020/nybg.ejpam.v12i2.3419.

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In Algebraic Coding Theory, all linear codes are described by generator matrices. Any linear code has many generator matrices which are equivalent. It is important to find the number of the generator matrices for constructing of these codes. In this paper, we study Z_2 Z_4 Z_8-additive codes, which are the extension of recently introduced Z_2 Z_4-additive codes. We count the number of arbitrary Z_2 Z_4 Z_8-additive codes. Then we investigate connections to Z_2 Z_4 and Z_2 Z_8-additive codes with Z_2 Z_4 Z_8, and give some illustrative examples.
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21

Lu, Jianfeng, Weiling Cheng, Shanqing Zhang, Li Li, Zaorang Yang, and Chin-Chen Chang. "A Novel Aesthetic QR Code Algorithm Based on Hybrid Basis Vector Matrices." Symmetry 10, no. 11 (October 25, 2018): 543. http://dx.doi.org/10.3390/sym10110543.

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Recently, more and more research has focused on the beautification technology of QR (Quick Response) codes. In this paper, a novel algorithm based on the XOR (exclusive OR) mechanism of hybrid basis vector matrices and a background image synthetic strategy is proposed. The hybrid basis vector matrices include the reverse basis vector matrix (RBVM) and positive basis vector matrix (PBVM). Firstly, the RBVM and PBVM are obtained by the Gauss–Jordan elimination method, according to the characteristics of the RS code. Secondly, the modification of the parity area of the QR code can be applied with the XOR operation of the RBVM, and the XOR operation of the PBVM is used to change the data area of the QR code. So, the QR code can be modified to be very close to the background image without impacting the error-correction ability. Finally, in order to further decrease the difference between the QR code and the background image, a new synthesis strategy is adopted in order to obtain a better aesthetic effect. The experimental results show that it obtains a better visual effect without the sacrificing recognition rate.
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Sergeev, M. B., V. A. Nenashev, and A. M. Sergeev. "Nested code sequences of Barker — Mersenne — Raghavarao." Information and Control Systems, no. 3 (June 21, 2019): 71–81. http://dx.doi.org/10.31799/1684-8853-2019-3-71-81.

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Introduction: The problem of noise-free encoding for an open radio channel is of great importance for data transfer. The results presented in this paper are aimed at stimulating scientific interest in new codes and bases derived from quasi-orthogonal matrices, as a basis for the revision of signal processing algorithms.Purpose: Search for new code sequences as combinations of codes formed from the rows of Mersenne and Raghavarao quasi-orthogonal matrices, as well as complex and more efficient Barker — Mersenne — Raghavarao codes.Results: We studied nested code sequences derived from the rows of quasi-orthogonal cyclic matrices of Mersenne, Raghavarao and Hadamard, providing estimates for the characteristics of the autocorrelation function of nested Barker, Mersenne and Raghavarao codes, and their combinations: in particular, the ratio between the main peak and the maximum positive and negative “side lobes”. We have synthesized new codes, including nested ones, formed on the basis of quasi-orthogonal matrices with better characteristics than the known Barker codes and their nested constructions. The results are significant, as this research influences the establishment and development of methods for isolation, detection and processing of useful information. The results of the work have a long aftermath because new original code synthesis methods need to be studied, modified, generalized and expanded for new application fields.Practical relevance: The practical application of the obtained results guarantees an increase in accuracy of location systems, and detection of a useful signal in noisy background. In particular, these results can be used in radar systems with high distance resolution, when detecting physical objects, including hidden ones.
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Nisar, Kottakkaran Soopy, Himali Sarangal, Simrandeep Singh Thapar, Mohammed Qutubuddin, and Mohammed Rahmath. "Performance Analysis of Permutation Matrix Zero Cross Correlation Code for SAC-OCDMA Systems." European Journal of Engineering Research and Science 3, no. 1 (January 22, 2018): 15. http://dx.doi.org/10.24018/ejers.2018.3.1.576.

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SAC-OCDMA systems are picking up prominence because of their property of low Multiple Access Interference (MAI). This paper deals with zero cross-correlation (ZCC) by considering permutation matrices (PM). The properties and performance analysis of PM-ZCC code are given in this study. The obtained results have shown that PM-ZCC code can achieve better BER for more number of users. In PM-ZCC code, the code length is neither too short nor too long which is the good property of encoder-decoder design structure.
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24

Kumar, Sandeep. "A CAS Approach to Handle the Anisotropic Hooke’s Law for Cancellous Bone and Wood." Chinese Journal of Engineering 2014 (March 23, 2014): 1–28. http://dx.doi.org/10.1155/2014/487314.

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The present research entirely relies on the Computer Algebric Systems (CAS) to develop techniques for the data analysis of the sets of elastic constant data measurements. In particular, this study deals with the development of some appropriate programming codes that favor the data analysis of known values of elastic constants for cancellous bone, hardwoods, and softwood species. More precisely, a “Mathematica” code, which has an ability to unfold a fourth-order elasticity tensor is discussed. Also, an effort towards the fabrication of an appropriate “MAPLE” code has been exposed, that can calculate not only the eigenvalues and eigenvectors for cancellous bone, hardwoods, and softwood species, but also computes the nominal average of eigenvectors, average eigenvectors, average eigenvalues, and the average elasticity matrices for these materials. Further, using such a MAPLE code, the histograms corresponding to average elasticity matrices of 15 hardwood species have been plotted and the graphs for I, II, III, IV, V, and VI eigenvalues of each hardwood species against their apparent densities are also drawn.
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Uryvsky, Leonid, and Serhii Osypchuk. "The Analytical Description of Regular LDPC Codes Correcting Ability." Transport and Telecommunication Journal 15, no. 3 (September 1, 2014): 177–84. http://dx.doi.org/10.2478/ttj-2014-0015.

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Abstract The analytical description of regular LDPC (Low-Density Parity Check) codes correcting ability has been investigated. The statistical dependencies for the maximum number of corrected bits per the code word as a function of LDPC code word length and code rate are given based on multiple experimental analyses of LDPC check matrices. The analytical expressions are proposed for the cases of linear, exponential and polynomial approximations of given results. The most exact analytical formula is proved by criterion of the minimum divergence between the experimental and theoretical results.
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Farkaš, Peter, and Frank Schindler. "Construction for obtaining trellis run length limited error control codes from convolutional codes." Journal of Electrical Engineering 68, no. 5 (September 1, 2017): 401–4. http://dx.doi.org/10.1515/jee-2017-0074.

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Abstract Recently a new construction of run length limited block error control codes based on control matrices of linear block codes was proposed. In this paper a similar construction for obtaining trellis run length limited error control codes from convolutional codes is described. The main advantage of it, beyond its simplicity is that it does not require any additional redundancy except the one which is already contained in the original convolutional error control code. One example is presented how to get such a code from a convolutional low density parity check code.
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ASHINO, RYUICHI, and RÉMI VAILLANCOURT. "PHASE TRANSITIONS IN ERROR CORRECTING AND COMPRESSED SENSING BY ℓ1 LINEAR PROGRAMMING." International Journal of Wavelets, Multiresolution and Information Processing 11, no. 04 (July 2013): 1360004. http://dx.doi.org/10.1142/s0219691313600047.

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In correcting a real linear code y = Bx + w by ℓ1 linear programming, where the encoding matrix B ∈ ℝm × n has full rank with m ≥ n and the noise w ∈ ℝm is a sparse random vector, it is numerically observed that the breakdown points of 50% successes in recovering the input vector x ∈ ℝn from the corrupted oversampled measurement y lie on the Donoho–Tanner curves when reflected in their midpoint. The curves of 50% successes in solving underdetermined systems, z = Aw, by ℓ1 linear programming with uniformly distributed compressed sensing matrices A ∈ ℝd × m, where d < m and w is a sparse vector, have been numerically observed and recently shown to coincide with the Donoho–Tanner curves for normally-distributed compressed sensing matrices A derived from geometric combinatorics. When n ≤ m/2, correcting a linear code is faster if done directly by ℓ1 linear programming. However, when n > m/2, to save computing time, this problem can be transformed into an underdetermined compressed sensing problem, Aw = z := Ay, for the syndrome z by a full rank matrix A ∈ ℝd × m, d = m – n, such that AB = 0. For this purpose, to have equivalently high mean breakdown points by ℓ1 linear programming, one can use uniformly distributed random matrices A ∈ ℝ(m-n) × m and matrices B ∈ ℝm × n with orthonormal columns spanning the null space of A. Two exceptional cases have been found. Numerical results are collected in figures and tables.
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Nguyen, Duc, and Sunghwan Kim. "New Constructions of Quantum Stabilizer Codes Based on Difference Sets." Symmetry 10, no. 11 (November 19, 2018): 655. http://dx.doi.org/10.3390/sym10110655.

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In this paper, new conditions on parameters in difference sets are derived to satisfy symplectic inner product, and new constructions of quantum stabilizer codes are proposed from the conditions. The conversion of the difference sets into parity-check matrices is first explained. Then, the proposed code construction is composed of three steps, which are to choose the generators of quantum stabilizer code, to determine the quantum stabilizer groups, and to determine subspace codewords with large minimum distance. The quantum stabilizer codes with various length are also presented to explain the practicality of the code construction. The proposed design can be applied to quantum stabilizer code construction based on combinatorial design.
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Nguyen, Duc Manh, and Sunghwan Kim. "A novel construction for quantum stabilizer codes based on binary formalism." International Journal of Modern Physics B 34, no. 08 (March 24, 2020): 2050059. http://dx.doi.org/10.1142/s0217979220500599.

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In this research, we propose a novel construction of quantum stabilizer code based on a binary formalism. First, from any binary vector of even length, we generate the parity-check matrix of the quantum code from a set composed of elements from this vector and its relations by shifts via subtraction and addition. We prove that the proposed matrices satisfy the condition constraint for the construction of quantum codes. Finally, we consider some constraint vectors which give us quantum stabilizer codes with various dimensions and a large minimum distance with code length from six to twelve digits.
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Chow, Woon N., David G. Simpson, John W. Bigbee, and Raymond J. Colello. "Evaluating neuronal and glial growth on electrospun polarized matrices: bridging the gap in percussive spinal cord injuries." Neuron Glia Biology 3, no. 2 (May 2007): 119–26. http://dx.doi.org/10.1017/s1740925x07000580.

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AbstractOne of the many obstacles to spinal cord repair following trauma is the formation of a cyst that impedes axonal regeneration. Accordingly, we examined the potential use of electrospinning to engineer an implantable polarized matrix for axonal guidance. Polydioxanone, a resorbable material, was electrospun to fabricate matrices possessing either aligned or randomly oriented fibers. To assess the extent to which fiber alignment influences directional neuritic outgrowth, rat dorsal root ganglia (DRGs) were cultured on these matrices for 10 days. Using confocal microscopy, neurites displayed a directional growth that mimicked the fiber alignment of the underlying matrix. Because these matrices are generated from a material that degrades with time, we next determined whether a glial substrate might provide a more stable interface between the resorbable matrix and the outgrowing axons. Astrocytes seeded onto either aligned or random matrices displayed a directional growth pattern similar to that of the underlying matrix. Moreover, these glia-seeded matrices, once co-cultured with DRGs, conferred the matrix alignment to and enhanced outgrowth exuberance of the extending neurites. These experiments demonstrate the potential for electrospinning to generate an aligned matrix that influences both the directionality and growth dynamics of DRG neurites.
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Elkaranshawy, Hesham A., Ahmed A. H. Elerian, and Walied I. Hussien. "A Corotational Formulation Based on Hamilton’s Principle for Geometrically Nonlinear Thin and Thick Planar Beams and Frames." Mathematical Problems in Engineering 2018 (August 14, 2018): 1–22. http://dx.doi.org/10.1155/2018/2670462.

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A corotational finite element formulation for two-dimensional beam elements with geometrically nonlinear behavior is presented. The formulation separates the rigid body motion from the pure deformation which is always small relative to the corotational element frame. The stiffness matrices and the mass matrices are evaluated using both Euler-Bernoulli and Timoshenko beam models to reveal the shear effect in thin and thick beams and frames. The nonlinear equilibrium equations are developed using Hamilton’s principle and are defined in the global coordinate system. A MATLAB code is developed for the numerical solution. In static analysis, the code employed an iterative method based on the full Newton-Raphson method without incremental loading, while, in dynamic analysis, the Newmark direct integration implicit method is also utilized. Several examples of flexible beams and frames with large displacements are presented. Not only is the method simple and time-saving, but it is also highly effective and highly accurate.
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Yen, Chih-Ta, and Chih-Ming Chen. "BER Analysis Using Beat Probability Method of 3D Optical CDMA Networks with Double Balanced Detection." Mathematical Problems in Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/456829.

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This study proposes novel three-dimensional (3D) matrices of wavelength/time/spatial code for code-division multiple-access (OCDMA) networks, with a double balanced detection mechanism. We construct 3D carrier-hopping prime/modified prime (CHP/MP) codes by extending a two-dimensional (2D) CHP code integrated with a one-dimensional (1D) MP code. The corresponding coder/decoder pairs were based on fiber Bragg gratings (FBGs) and tunable optical delay lines integrated with splitters/combiners. System performance was enhanced by the low cross correlation properties of the 3D code designed to avoid the beat noise phenomenon. The CHP/MP code cardinality increased significantly compared to the CHP code under the same bit error rate (BER). The results indicate that the 3D code method can enhance system performance because both the beating terms and multiple-access interference (MAI) were reduced by the double balanced detection mechanism. Additionally, the optical component can also be relaxed for high transmission scenery.
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URKULLU MARTIN, GORKA, IGOR FERNANDEZ DE BUSTOS, ANDER OLABARRIETA, and RUBEN ANSOLA. "EFFICIENCY ASSESSMENT OF THE DIRECT INTEGRATION METHOD BY CENTRAL DIFFERENCES (DIMCD)." DYNA 96, no. 5 (September 1, 2021): 512–19. http://dx.doi.org/10.6036/10004.

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The direct integration method by central differences (DIMCD) is an explicit method of order two for integrating the equations governing the dynamic analysis of multibody systems. So far, development has focused only on verifying the quality of the results. In this paper, it is shown that in addition to providing optimal results, it is also competitive from the point of view of computational efficiency, at least for systems with up to six bodies. For this purpose, an appropriate implementation of the method in a compiled language is presented. In turn, it is shown that the methodology is suitable for modeling in sparse matrices, although the proposed implementation is based on dense matrices. The resulting code is applied to different benchmark examples. Results from various commercial software are also included. Keywords: Computational efficiency, multibody dynamics, central differences, null space, dense matrices, quaternions
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34

Carayol, Cécile. "La Ligne rouge de Hans Zimmer. Matrice d’un « nouvel Hollywood » électro-minimaliste et contemplatif." Revue musicale OICRM 5, no. 2 (November 30, 2018): 79–102. http://dx.doi.org/10.7202/1054148ar.

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À travers une étude comparative de plusieurs films au contexte narratif contemplatif comme La Ligne Rouge (Terrence Malick, 1998), partition-matrice qui a marqué une nette évolution dans l’esthétique zimmerienne, Hannibal (Ridley Scott, 2001), Da Vinci Code (de Ron Howard, 2006) « synthèse la plus raffinée des influences du minimalisme » (Berthomieu 2013, p. 698), jusqu’à des partitions que Hans Zimmer a composées pour Christopher Nolan comme Inception (2010) et Interstellar (2014), cet article montre de quelle manière Zimmer parvient pleinement à imposer un nouveau courant musical à Hollywood en intégrant une écriture épurée imprégnée notamment par le minimalisme d’Arvo Pärt à des boucles élaborées par des synthétiseurs ou des sons électroniques : si les hommages ciblés à des oeuvres d’Arvo Pärt sont propices à souligner le tourment intérieur ou le recueillement sombre, Zimmer reprend également des principes plus généraux de cette forme de minimalisme – souvent une oscillation immuable et répétée à l’infini autour d’un accord parfait mineur – presque systématiquement mêlés à cette énergie créative de timbres hybrides, afin de créer une autre temporalité apportant une forme d’inéluctable à l’image tout en maintenant empathie et synchronisme discret comme soutiens à l’action (La Ligne rouge, Batman Begins, Da Vinci Code, Inception). La quinte – seule, en ostinato ou répétée sur un motif – quintessence du tintinnabuli zimmerien (au-delà de l’accord parfait pärtien), souligne l’instant suspendu (La Ligne rouge, Hannibal, Interstellar), tandis qu’une forme de radicalisation de ce minimalisme qui va parfois jusqu’à la négation de toute mélodie, remplacée par une note unique, devenue texture abstraite, ou par un cluster diatonique en blend mode (Da Vinci Code, Interstellar), évoque le désespoir, la mort, ou le néant. Loin d’être un « monde » qui « se réduit alors au vide d’un présent sans rêve » (Berthomieu 2004, p. 75), l’écriture électro-minimaliste et contemplative de Zimmer, marquée par une cohérence narrative forte, est connectée au programme esthétique des films auxquels elle se destine.
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Wang, Xiang, and Fang-Wei Fu. "Deterministic Construction of Compressed Sensing Matrices from Codes." International Journal of Foundations of Computer Science 28, no. 02 (February 2017): 99–109. http://dx.doi.org/10.1142/s0129054117500071.

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Compressed sensing is a sparse sampling theory. Compared with the Nyquist-Shannon sampling theory, in compressed sensing one could reconstruct a sparse signal from a few linear and non-adaptive measurements. How to construct a good sensing matrix which captures the full information of a sparse signal is an important problem in compressed sensing. In this paper, we present a new deterministic construction using a linear or nonlinear code, which is a generalization of DeVore’s construction and Li et al.’s construction. By choosing some appropriate linear codes or nonlinear codes, we will construct some good binary sensing matrices which are superior to DeVore’s ones and Li et al.’s ones.
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Mitsa, Oleksandr, Yurii Horoshko, and Serhii Vapnichnyi. "Reduction of programs execution time for tasks related to sequences or matrices." SHS Web of Conferences 75 (2020): 04019. http://dx.doi.org/10.1051/shsconf/20207504019.

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The article discusses three approaches to reducing runtime of the programs, which are solutions of Olympiad tasks on computer science, related to sequences or matrices. The first approach is based on the representation of some sequences in matrix form and then the program of calculating the members of the sequence will have asymptotics equal to the time complexity of the exponentiation algorithm and will be O(log (n)). The second approach is to upgrade the known code to obtain significant reduction of the program runtime. This approach is very important to know for scientists who write code for scientific researches and are faced with matrix multiplication operations. The third approach is based on reducing time complexity by search for regularities; the author's task is presented and this approach is used to solve it.
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37

Dai, Hang, and Yongtao Guan. "Nubeam-dedup: a fast and RAM-efficient tool to de-duplicate sequencing reads without mapping." Bioinformatics 36, no. 10 (February 24, 2020): 3254–56. http://dx.doi.org/10.1093/bioinformatics/btaa112.

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Abstract Summary We present Nubeam-dedup, a fast and RAM-efficient tool to de-duplicate sequencing reads without reference genome. Nubeam-dedup represents nucleotides by matrices, transforms reads into products of matrices, and based on which assigns a unique number to a read. Thus, duplicate reads can be efficiently removed by using a collisionless hash function. Compared with other state-of-the-art reference-free tools, Nubeam-dedup uses 50–70% of CPU time and 10–15% of RAM. Availability and implementation Source code in C++ and manual are available at https://github.com/daihang16/nubeamdedup and https://haplotype.org. Supplementary information Supplementary data are available at Bioinformatics online.
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38

Chavarría Lara, Sebastián de Jesús. "Sistema normativo, principios implícitos y fórmula del peso." La Revista de Derecho 39 (December 14, 2018): 21–32. http://dx.doi.org/10.5377/lrd.v39i9.6789.

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Se realizará una reconstrucción y análisis de la sentencia de la Corte Suprema de Justicia de Honduras, expedientes RI 1343-14 acumulada con el RI 0243-15. Para ello, se utilizarán las matrices lógicas para sistemas normativos de Alchourrón & Bulygin, el modelo para inferir principios implícitos de Juan Pablo Alonso y el procedimiento de ponderación de principios de Robert Alexy.
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39

Brandts, Jan, and Apo Cihangir. "Enumeration and investigation of acute 0/1-simplices modulo the action of the hyperoctahedral group." Special Matrices 5, no. 1 (August 28, 2017): 158–201. http://dx.doi.org/10.1515/spma-2017-0014.

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Abstract The convex hull of n + 1 affinely independent vertices of the unit n-cube In is called a 0/1-simplex. It is nonobtuse if none its dihedral angles is obtuse, and acute if additionally none of them is right. In terms of linear algebra, acute 0/1-simplices in In can be described by nonsingular 0/1-matrices P of size n × n whose Gramians G = PTP have an inverse that is strictly diagonally dominant, with negative off-diagonal entries [6, 7]. The first part of this paper deals with giving a detailed description of how to efficiently compute, by means of a computer program, a representative from each orbit of an acute 0/1-simplex under the action of the hyperoctahedral group Bn [17] of symmetries of In. A side product of the investigations is a simple code that computes the cycle index of Bn, which can in explicit form only be found in the literature [11] for n ≤ 6. Using the computed cycle indices for B3, . . . ,B11 in combination with Pólya’s theory of enumeration shows that acute 0/1-simplices are extremely rare among all 0/1-simplices. In the second part of the paper, we study the 0/1-matrices that represent the acute 0/1-simplices that were generated by our code from a mathematical perspective. One of the patterns observed in the data involves unreduced upper Hessenberg 0/1-matrices of size n × n, block-partitioned according to certain integer compositions of n. These patterns will be fully explained using a so-called One Neighbor Theorem [4]. Additionally, we are able to prove that the volumes of the corresponding acute simplices are in one-to-one correspondence with the part of Kepler’s Tree of Fractions [1, 24] that enumerates ℚ ⋂ (0, 1). Another key ingredient in the proofs is the fact that the Gramians of the unreduced upper Hessenberg matrices involved are strictly ultrametric [14, 26] matrices.
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40

Luong, Tran Thi, Nguyen Ngoc Cuong, and Luong The Dung. "The preservation of good cryptographyic properties of MDS matrix under direct exponent transformation." Journal of Computer Science and Cybernetics 31, no. 4 (January 26, 2016): 291. http://dx.doi.org/10.15625/1813-9663/31/4/7059.

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Maximum Distance Separable (MDS) code has been studied for a long time in the coding theory and has been applied widely in cryptography. The methods for transforming an MDS into other ones have been proposed by many authors in the literature. These methods are called MDS matrix transformations in order to generate different MDS matrices (dynamic MDS matrices) from an existing one. In this paper, some new results on the preservation of many good cryptographic properties of MDS matrices under direct exponent transformation are presented. These good cryptographic properties include MDS, involutory, symmetric, recursive (exponent of a companion matrix), the number of 1's and distinct elements in a matrix, circulant and circulant-like. In addition, these results are shown to have important applications in constructing dynamic diffusion layers for block ciphers. The strength of the ciphers against developing cryptanalytic techniques can be enhanced by the dynamic MDS diffusion layers.
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41

Guo, Shaowei, Idan Redenski, and Shulamit Levenberg. "Spinal Cord Repair: From Cells and Tissue Engineering to Extracellular Vesicles." Cells 10, no. 8 (July 23, 2021): 1872. http://dx.doi.org/10.3390/cells10081872.

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Spinal cord injury (SCI) is a debilitating condition, often leading to severe motor, sensory, or autonomic nervous dysfunction. As the holy grail of regenerative medicine, promoting spinal cord tissue regeneration and functional recovery are the fundamental goals. Yet, effective regeneration of injured spinal cord tissues and promotion of functional recovery remain unmet clinical challenges, largely due to the complex pathophysiology of the condition. The transplantation of various cells, either alone or in combination with three-dimensional matrices, has been intensively investigated in preclinical SCI models and clinical trials, holding translational promise. More recently, a new paradigm shift has emerged from cell therapy towards extracellular vesicles as an exciting “cell-free” therapeutic modality. The current review recapitulates recent advances, challenges, and future perspectives of cell-based spinal cord tissue engineering and regeneration strategies.
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42

Maziero, Jonas. "Computing partial traces and reduced density matrices." International Journal of Modern Physics C 28, no. 01 (January 2017): 1750005. http://dx.doi.org/10.1142/s012918311750005x.

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Taking partial traces (PTrs) for computing reduced density matrices, or related functions, is a ubiquitous procedure in the quantum mechanics of composite systems. In this paper, we present a thorough description of this function and analyze the number of elementary operations (ops) needed, under some possible alternative implementations, to compute it on a classical computer. As we note, it is worthwhile doing some analytical developments in order to avoid making null multiplications and sums, what can considerably reduce the ops. For instance, for a bipartite system [Formula: see text] with dimensions [Formula: see text] and [Formula: see text] and for [Formula: see text], while a direct use of PTr definition applied to [Formula: see text] requires [Formula: see text] ops, its optimized implementation entails [Formula: see text] ops. In the sequence, we regard the computation of PTrs for general multipartite systems and describe Fortran code provided to implement it numerically. We also consider the calculation of reduced density matrices via Bloch’s parametrization with generalized Gell Mann’s matrices.
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43

Trefethen, Lloyd N. "Computation of pseudospectra." Acta Numerica 8 (January 1999): 247–95. http://dx.doi.org/10.1017/s0962492900002932.

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There is more to the computation of pseudospectra than the obvious algorithm of computing singular value decompositions on a grid and sending the results to a contour plotter. Other methods may be hundreds of times faster. The state of the art is reviewed, with emphasis on methods for dense matrices, and a Matlab code is given.
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44

Kessler, Christoph W. "Pattern-Driven Automatic Parallelization." Scientific Programming 5, no. 3 (1996): 251–74. http://dx.doi.org/10.1155/1996/406379.

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This article describes a knowledge-based system for automatic parallelization of a wide class of sequential numerical codes operating on vectors and dense matrices, and for execution on distributed memory message-passing multiprocessors. Its main feature is a fast and powerful pattern recognition tool that locally identifies frequently occurring computations and programming concepts in the source code. This tool also works for dusty deck codes that have been "encrypted" by former machine-specific code transformations. Successful pattern recognition guides sophisticated code transformations including local algorithm replacement such that the parallelized code need not emerge from the sequential program structure by just parallelizing the loops. It allows access to an expert's knowledge on useful parallel algorithms, available machine-specific library routines, and powerful program transformations. The partially restored program semantics also supports local array alignment, distribution, and redistribution, and allows for faster and more exact prediction of the performance of the parallelized target code than is usually possible.
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45

Lafita, Aleix, and Alex Bateman. "Modelling structural rearrangements in proteins using Euclidean distance matrices." F1000Research 9 (July 20, 2020): 728. http://dx.doi.org/10.12688/f1000research.25235.1.

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Proteins undergo large structural rearrangements such as circular permutations, dimerisation via domain swapping, and loss of core secondary structure elements in domain atrophy, among others. These structural changes can be naturally represented as distance matrix transformations, exploiting their conserved native residue contacts at the protein core. Here we present an homology modelling approach to formulate structural rearrangements as a Euclidean distance matrix (EDM) problem and use it to build their 3D structures. This modelling approach aims to be lightweight, flexible and fast, suitable for large-scale analyses. Models are typically coarse-grained and solely based on protein geometry. We demonstrate various applications of EDM-based modelling for protein structure analysis and release an open repository with the source code at: https://github.com/lafita/protein-edm-demo.
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46

Siewertsen, E., J. Piwonski, and T. Slawig. "Porting marine ecosystem model spin-up using transport matrices to GPUs." Geoscientific Model Development 6, no. 1 (January 8, 2013): 17–28. http://dx.doi.org/10.5194/gmd-6-17-2013.

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Abstract. We have ported an implementation of the spin-up for marine ecosystem models based on transport matrices to graphics processing units (GPUs). The original implementation was designed for distributed-memory architectures and uses the Portable, Extensible Toolkit for Scientific Computation (PETSc) library that is based on the Message Passing Interface (MPI) standard. The spin-up computes a steady seasonal cycle of ecosystem tracers with climatological ocean circulation data as forcing. Since the transport is linear with respect to the tracers, the resulting operator is represented by matrices. Each iteration of the spin-up involves two matrix-vector multiplications and the evaluation of the used biogeochemical model. The original code was written in C and Fortran. On the GPU, we use the Compute Unified Device Architecture (CUDA) standard, a customized version of PETSc and a commercial CUDA Fortran compiler. We describe the extensions to PETSc and the modifications of the original C and Fortran codes that had to be done. Here we make use of freely available libraries for the GPU. We analyze the computational effort of the main parts of the spin-up for two exemplar ecosystem models and compare the overall computational time to those necessary on different CPUs. The results show that a consumer GPU can compete with a significant number of cluster CPUs without further code optimization.
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47

Siewertsen, E., J. Piwonski, and T. Slawig. "Porting marine ecosystem model spin-up using transport matrices to GPUs." Geoscientific Model Development Discussions 5, no. 3 (July 31, 2012): 2179–214. http://dx.doi.org/10.5194/gmdd-5-2179-2012.

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Abstract. We have ported an implementation of the spin-up for marine ecosystem models based on the "Transport Matrix Method" to graphics processing units (GPUs). The original implementation was designed for distributed-memory architectures and uses the PETSc library that is based on the "Message Passing Interface (MPI)" standard. The spin-up computes a steady seasonal cycle of the ecosystem tracers with climatological ocean circulation data as forcing. Since the transport is linear with respect to the tracers, the resulting operator is represented in so-called "transport matrices". Each iteration of the spin-up involves two matrix-vector multiplications and the evaluation of the used biogeochemical model. The original code was written in C and Fortran. On the GPU, we use the CUDA standard, a specialized version of the PETSc toolkit and a CUDA Fortran compiler. We describe the extensions to PETSc and the modifications of the original C and Fortran codes that had to be done. Here we make use of freely available libraries for the GPU. We analyze the computational effort of the main parts of the spin-up for two exemplary ecosystem models and compare the overall computational time to those necessary on different CPUs. The results show that a consumer GPU can beat a significant number of cluster CPUs without further code optimization.
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48

Fu, Yunhui, Shin Matsushima, and Kenji Yamanishi. "Model Selection for Non-Negative Tensor Factorization with Minimum Description Length." Entropy 21, no. 7 (June 27, 2019): 632. http://dx.doi.org/10.3390/e21070632.

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Non-negative tensor factorization (NTF) is a widely used multi-way analysis approach that factorizes a high-order non-negative data tensor into several non-negative factor matrices. In NTF, the non-negative rank has to be predetermined to specify the model and it greatly influences the factorized matrices. However, its value is conventionally determined by specialists’ insights or trial and error. This paper proposes a novel rank selection criterion for NTF on the basis of the minimum description length (MDL) principle. Our methodology is unique in that (1) we apply the MDL principle on tensor slices to overcome a problem caused by the imbalance between the number of elements in a data tensor and that in factor matrices, and (2) we employ the normalized maximum likelihood (NML) code-length for histogram densities. We employ synthetic and real data to empirically demonstrate that our method outperforms other criteria in terms of accuracies for estimating true ranks and for completing missing values. We further show that our method can produce ranks suitable for knowledge discovery.
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Panizza, Matteo, Paolo Girardello, Enrico Garbin, Maria Rosa Valluzzi, Giuliana Cardani, Massimo Dalla Benetta, and Paolo Casadei. "On-Site Pull-Out Tests of Steel Anchor Spikes Applied to Brickwork Masonry." Key Engineering Materials 624 (September 2014): 266–74. http://dx.doi.org/10.4028/www.scientific.net/kem.624.266.

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Externally Bonded (EB) composite materials are becoming a widespread solution for strengthening interventions on masonry buildings, even Cultural Heritage structures, due to several positive aspects mainly related to their high strength-to-weight ratio. In recent years, beside common epoxy-based Fibre-Reinforced Polymers (FRP), steel-based composites have been proposed: they are composed by unidirectional high-strength steel cords that can be coupled to either organic (Steel Reinforced Polymers, SRP) or inorganic (Steel Reinforced Grouts, SRG) matrices, in relation to their optimized spacing. The bond behaviour of all these EB composites has a strong influence over the effectiveness of interventions, since the detachment of reinforcements from the substrate generally represents the weaker failure mechanism. In order to improve this aspect, several anchorage devices have been proposed, being spikes, among them, one of the most suitable for masonry supports. Spikes are made of a bundle of fibres partly in the form of a bar, to be inserted and glued into a hole drilled in the substrate, and partly loose, to be spread and connected to reinforcement strips. Despite their importance also from a design point of view and considering the variety of shapes and materials, there are still few investigations in this field, being clear that both the spike-to-reinforcement and the spike-to-masonry connections need to be studied. Focused on the spike-to-masonry connection, this paper is aimed at investigating the performance of steel cord spikes applied to existing clay brick masonry, by means of overall 39 pull-out tests carried out taking into account the bonded length (equal to the hole depth), the type of embedding material and the number of steel cords forming the anchorage. The main results of this experimentation are herein presented and discussed.
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Philcox, Oliver H. E., Daniel J. Eisenstein, Ross O’Connell, and Alexander Wiegand. "rascalc: a jackknife approach to estimating single- and multitracer galaxy covariance matrices." Monthly Notices of the Royal Astronomical Society 491, no. 3 (November 18, 2019): 3290–317. http://dx.doi.org/10.1093/mnras/stz3218.

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ABSTRACT To make use of clustering statistics from large cosmological surveys, accurate and precise covariance matrices are needed. We present a new code to estimate large-scale galaxy two-point correlation function (2PCF) covariances in arbitrary survey geometries that, due to new sampling techniques, runs ∼104 times faster than previous codes, computing finely binned covariance matrices with negligible noise in less than 100 CPU-hours. As in previous works, non-Gaussianity is approximated via a small rescaling of shot noise in the theoretical model, calibrated by comparing jackknife survey covariances to an associated jackknife model. The flexible code, rascalc, has been publicly released, and automatically takes care of all necessary pre- and post-processing, requiring only a single input data set (without a prior 2PCF model). Deviations between large-scale model covariances from a mock survey and those from a large suite of mocks are found to be indistinguishable from noise. In addition, the choice of input mock is shown to be irrelevant for desired noise levels below ∼105 mocks. Coupled with its generalization to multitracer data sets, this shows the algorithm to be an excellent tool for analysis, reducing the need for large numbers of mock simulations to be computed.
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