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1
Wan, K. F., P. C. Ching et C. K. Li. « A Set of Split-Matrix Ordered Walsh Functions ». Journal of Circuits, Systems and Computers 07, no 06 (décembre 1997) : 537–42. http://dx.doi.org/10.1142/s0218126697000401.
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A new set of Walsh functions is defined in terms of the split-matrix ordering. The intrinsic properties of the functions are analyzed. The relationship and the associated conversion rules between the newly defined functions and other typical Walsh functions are discussed. It is shown that the proposed Walsh functions provide a straighforward and efficient algorithm for fast Discrete Walsh Transformation.
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ASAHI, Hideyasu. « A Function Generator for Walsh Order Hadamard Matrix and Fast Walsh-Hadamard Transform ». Geoinformatics 11, no 1 (2000) : 3–9. http://dx.doi.org/10.6010/geoinformatics1990.11.1_3.
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Alghamdi, Mohammed A., et M. Mursaleen. « Hankel matrix transformation of the Walsh–Fourier series ». Applied Mathematics and Computation 224 (novembre 2013) : 278–82. http://dx.doi.org/10.1016/j.amc.2013.08.075.
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Tsuneda, Akio. « Orthogonal Chaotic Binary Sequences Based on Bernoulli Map and Walsh Functions ». Entropy 21, no 10 (24 septembre 2019) : 930. http://dx.doi.org/10.3390/e21100930.
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The statistical properties of chaotic binary sequences generated by the Bernoulli map and Walsh functions are discussed. The Walsh functions are based on a 2 k × 2 k Hadamard matrix. For general k (= 1 , 2 , ⋯ ), we will prove that 2 k - 1 Walsh functions can generate essentially different balanced and i.i.d. binary sequences that are orthogonal to each other.
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CHOU, JYH-HORNG, et ING-RONG HORNG. « Simple methods for the shift-transformation matrix, direct-product matrix and summation matrix of discrete Walsh series ». International Journal of Control 43, no 4 (avril 1986) : 1339–42. http://dx.doi.org/10.1080/00207178608933542.
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Samanta, Supriti, Goutam K. Maity et Subhadipta Mukhopadhyay. « Implementation of Orthogonal Codes Using MZI ». Micro and Nanosystems 12, no 3 (1 décembre 2020) : 159–67. http://dx.doi.org/10.2174/1876402912666200211121624.
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Background: In Code Division Multiple Access (CDMA)/Multi-Carrier CDMA (MCCDMA), Walsh-Hadamard codes are widely used for its orthogonal characteristics, and hence, it leads to good contextual connection property. These orthogonal codes are important because of their various significant applications. Objective: To use the Mach–Zehnder Interferometer (MZI) for all-optical Walsh-Hadamard codes is implemented in this present paper. Method: The Mach–Zehnder Interferometer (MZI) is considered for the Tree architecture of Semiconductor Optical Amplifier (SOA). The second-ordered Hadamard and the inverse Hadamard matrix are constructed using SOA-MZIs. Higher-order Hadamard matrix (H4) formed by the process of Kronecker product with lower-order Hadamard matrix (H2) is also analyzed and constructed. Results: To experimentally get the result from these schemes, some design issues e,g Time delay, nonlinear phase modulation, extinction ratio, and synchronization of signals are the important issues. Lasers of wavelength 1552 nm and 1534 nm can be used as input and control signals, respectively. As the whole system is digital, intensity losses due to couplers in the interconnecting stage may not create many problems in producing the desired optical bits at the output. The simulation results were obtained by Matlab-9. Here, Hadamard H2 (2×2) matrix output beam intensity (I ≈ 108 w.m-2) for different values of inputs. Conclusion: Implementation of Walsh-Hadamard codes using MZI is explored in this paper, and experimental results show the better performance of the proposed scheme compared to recently reported methods using electronic circuits regarding the issues of versatility, reconfigurability, and compactness. The design can be used and extended for diverse applications for which Walsh-Hadamard codes are required.
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Au-Yeung, Enrico. « Sparse reconstruction with multiple Walsh matrices ». Advances in Pure and Applied Mathematics 10, no 3 (1 juillet 2019) : 221–39. http://dx.doi.org/10.1515/apam-2017-0047.
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Abstract The problem of how to find a sparse representation of a signal is an important one in applied and computational harmonic analysis. It is closely related to the problem of how to reconstruct a sparse vector from its projection in a much lower-dimensional vector space. This is the setting of compressed sensing, where the projection is given by a matrix with many more columns than rows. We introduce a class of random matrices that can be used to reconstruct sparse vectors in this paradigm. These matrices satisfy the restricted isometry property with overwhelming probability. We also discuss an application in dimensionality reduction where we initially discovered this class of matrices.
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Alotaibi, Abdullah, et M. Mursaleen. « Applications of Hankel and Regular Matrices in Fourier Series ». Abstract and Applied Analysis 2013 (2013) : 1–3. http://dx.doi.org/10.1155/2013/947492.
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Recently, Alghamdi and Mursaleen (2013) used the Hankel matrix to determine the necessary and suffcient condition to find the sum of the Walsh-Fourier series. In this paper, we propose to use the Hankel matrix as well as any general nonnegative regular matrix to obtain the necessary and sufficient conditions to sum the derived Fourier series and conjugate Fourier series.
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LI, Yu, He-xin CHEN, Ai-jun SANG et Hua FENG. « Four-dimensional matrix Walsh transform for lossless compression of color video ». Journal of China Universities of Posts and Telecommunications 17, no 3 (juin 2010) : 123–28. http://dx.doi.org/10.1016/s1005-8885(09)60461-1.
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Ebregbe, David, et Wei Bo Deng. « Orthogonal Binary Waveform Optimization for Mimo Radar Systems ». Applied Mechanics and Materials 239-240 (décembre 2012) : 376–81. http://dx.doi.org/10.4028/www.scientific.net/amm.239-240.376.
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Waveform optimization for multiple-input multiple-output (MIMO) radar systems for good autocorrelation and crosscorrelation properties based on the direct design of the set of orthogonal transmitted time series is considered. Exploiting the orthogonality of non identical walsh functions, which have been used successfully in spread spectrum communication, the Walsh-Hadamard matrix is used as the orthogonal binary signal set followed by the simulated annealing statistical optimization tool to provide an optimal orthogonal binary signal set with the desired correlation properties
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Anderyance, S., et M. Hadizadeh. « THE COMPUTATIONAL EFFICIENCY OF WALSH APPROXIMATION FOR TWO-DIMENSIONAL VOLTERRA INTEGRAL EQUATIONS ». Asian-European Journal of Mathematics 04, no 02 (juin 2011) : 263–70. http://dx.doi.org/10.1142/s1793557111000204.
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In this research, we give details of a new numerical method for the approximate solution of a general two-dimensional Volterra integral equation, using the discontinuous wavelet packets e.g. Walsh functions. The double Walsh approximation we have adopted utilizes a simple robust numerical scheme for approximate solution of the equations. The two-dimensional operational matrix of integration for each subinterval [Formula: see text] is explicitly constructed, where m is a power of 2. Finally the reliability and efficiency of the proposed scheme are demonstrated by some numerical results.
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Zhou, Zhong, Jiangfeng Hu, Fan Li, Junjie Zhang et Mingfeng Lei. « Elastic Modulus Prediction Model of Foamed Concrete Based on the Walsh Formula ». Applied Sciences 12, no 10 (19 mai 2022) : 5142. http://dx.doi.org/10.3390/app12105142.
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Foamed concrete consists of cement matrix and air-foam and has more complicated structure characteristics than normal concrete. However, current research on the elastic modulus of foamed concrete is still limited to empirical equations. In this work, a new theoretical prediction model was proposed for calculating the elastic modulus of foamed concrete. The elastic modulus calculation model for the spherical shell element of foamed concrete is constructed based on the Walsh formula and the assumption of spherical pores. Moreover, the theoretical prediction model is established by introducing the two-layer embedded model for the elastic modulus of foamed concrete. Then, the compressive test is employed to verify the accuracy of the model. The results show that the elastic modulus of foamed concrete decreases with the increase in porosity and matrix Poisson’s ratio, and increases with the increase in the matrix elastic modulus. The research results can improve the mechanical theories of foamed concrete materials and have good engineering application values.
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Save, Jagruti Ketan. « Walsh Transform based Feature vector generation for Image Database Classification ». International Journal of Electrical and Computer Engineering (IJECE) 6, no 3 (1 juin 2016) : 1176. http://dx.doi.org/10.11591/ijece.v6i3.8922.
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Thousands of images are generated everyday, which implies the need to build an easy, faster, automated classifier to classify and organize these images. Classification means selecting an appropriate class for a given image from a set of pre-defined classes. The main objective of this work is to explore feature vector generation using Walsh transform for classification. In the first method, we applied Walsh transform on the columns of an image to generate feature vectors. In second method, Walsh wavelet matrix is used for feature vector generation. In third method we proposed to apply vector quantization (VQ) on feature vectors generated by earlier methods. It gives better accuracy, fast computation and less storage space as compared with the earlier methods. Nearest neighbor and nearest mean classification algorithms are used to classify input test image. Image database used for the experimentation contains 2000 images. All these methods generate large number of outputs for single test image by considering four similarity measures, six sizes of feature vector, two ways of classification, four VQ techniques, three sizes of codebook, and five combinations of wavelet transform matrix generation. We observed improvement in accuracy from 63.22% to 74% (55% training data) through the series of techniques.
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Save, Jagruti Ketan. « Walsh Transform based Feature vector generation for Image Database Classification ». International Journal of Electrical and Computer Engineering (IJECE) 6, no 3 (1 juin 2016) : 1176. http://dx.doi.org/10.11591/ijece.v6i3.pp1176-1182.
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Thousands of images are generated everyday, which implies the need to build an easy, faster, automated classifier to classify and organize these images. Classification means selecting an appropriate class for a given image from a set of pre-defined classes. The main objective of this work is to explore feature vector generation using Walsh transform for classification. In the first method, we applied Walsh transform on the columns of an image to generate feature vectors. In second method, Walsh wavelet matrix is used for feature vector generation. In third method we proposed to apply vector quantization (VQ) on feature vectors generated by earlier methods. It gives better accuracy, fast computation and less storage space as compared with the earlier methods. Nearest neighbor and nearest mean classification algorithms are used to classify input test image. Image database used for the experimentation contains 2000 images. All these methods generate large number of outputs for single test image by considering four similarity measures, six sizes of feature vector, two ways of classification, four VQ techniques, three sizes of codebook, and five combinations of wavelet transform matrix generation. We observed improvement in accuracy from 63.22% to 74% (55% training data) through the series of techniques.
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Nayak, Dibyalekha, Kananbala Ray, Tejaswini Kar et Chiman Kwan. « Walsh–Hadamard Kernel Feature-Based Image Compression Using DCT with Bi-Level Quantization ». Computers 11, no 7 (4 juillet 2022) : 110. http://dx.doi.org/10.3390/computers11070110.
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To meet the high bit rate requirements in many multimedia applications, a lossy image compression algorithm based on Walsh–Hadamard kernel-based feature extraction, discrete cosine transform (DCT), and bi-level quantization is proposed in this paper. The selection of the quantization matrix of the block is made based on a weighted combination of the block feature strength (BFS) of the block extracted by projecting the selected Walsh–Hadamard basis kernels on an image block. The BFS is compared with an automatically generated threshold for applying the specific quantization matrix for compression. In this paper, higher BFS blocks are processed via DCT and high Q matrix, and blocks with lower feature strength are processed via DCT and low Q matrix. So, blocks with higher feature strength are less compressed and vice versa. The proposed algorithm is compared to different DCT and block truncation coding (BTC)-based approaches based on the quality parameters, such as peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) at constant bits per pixel (bpp). The proposed method shows significant improvements in performance over standard JPEG and recent approaches at lower bpp. It achieved an average PSNR of 35.61 dB and an average SSIM of 0.90 at a bpp of 0.5 and better perceptual quality with lower visual artifacts.
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Marti-Puig, P. « A Family of Fast Walsh Hadamard Algorithms With Identical Sparse Matrix Factorization ». IEEE Signal Processing Letters 13, no 11 (novembre 2006) : 672–75. http://dx.doi.org/10.1109/lsp.2006.879472.
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Selvaraj, Chikkanna R., et Suguna Selvaraj. « Matrix Transformations and Disk of Convergence in Interpolation Processes ». International Journal of Mathematics and Mathematical Sciences 2008 (2008) : 1–11. http://dx.doi.org/10.1155/2008/905635.
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Let denote the set of functions analytic in but not on . Walsh proved that the difference of the Lagrange polynomial interpolant of and the partial sum of the Taylor polynomial of converges to zero on a larger set than the domain of definition of . In 1980, Cavaretta et al. have studied the extension of Lagrange interpolation, Hermite interpolation, and Hermite-Birkhoff interpolation processes in a similar manner. In this paper, we apply a certain matrix transformation on the sequences of operators given in the above-mentioned interpolation processes to prove the convergence in larger disks.
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Laikova, L. G., T. A. Tereshchenko et Y. S. Yamnenko. « Matrix calculation of correlation characteristics based on spectral methods ». Технология и конструирование в электронной аппаратуре, no 3-4 (2020) : 11–16. http://dx.doi.org/10.15222/tkea2020.3-4.11.
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The paper is devoted to the problem of calculation of autocorrelation function that is important for solving the tasks that require finding the repeating intervals of the signal or defining the main frequency of the signal against the background of non-stationary noise. The authors propose an algorithm to transform the connection between arithmetic and logical correlation functions in oriented basis into the matrix form. Comparative analysis is conducted for the computational complexity of different types of autocorrelation functions using different spectral methods — Fourier, Walsh, and oriented basis transform.
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Saito, Naoki, et Yiqun Shao. « eGHWT : The Extended Generalized Haar–Walsh Transform ». Journal of Mathematical Imaging and Vision 64, no 3 (5 janvier 2022) : 261–83. http://dx.doi.org/10.1007/s10851-021-01064-w.
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AbstractExtending computational harmonic analysis tools from the classical setting of regular lattices to the more general setting of graphs and networks is very important, and much research has been done recently. The generalized Haar–Walsh transform (GHWT) developed by Irion and Saito (2014) is a multiscale transform for signals on graphs, which is a generalization of the classical Haar and Walsh–Hadamard transforms. We propose the extended generalized Haar–Walsh transform (eGHWT), which is a generalization of the adapted time–frequency tilings of Thiele and Villemoes (1996). The eGHWT examines not only the efficiency of graph-domain partitions but also that of “sequency-domain” partitions simultaneously. Consequently, the eGHWT and its associated best-basis selection algorithm for graph signals significantly improve the performance of the previous GHWT with the similar computational cost, $$O(N \log N)$$ O ( N log N ) , where N is the number of nodes of an input graph. While the GHWT best-basis algorithm seeks the most suitable orthonormal basis for a given task among more than $$(1.5)^N$$ ( 1.5 ) N possible orthonormal bases in $$\mathbb {R}^N$$ R N , the eGHWT best-basis algorithm can find a better one by searching through more than $$0.618\cdot (1.84)^N$$ 0.618 · ( 1.84 ) N possible orthonormal bases in $$\mathbb {R}^N$$ R N . This article describes the details of the eGHWT best-basis algorithm and demonstrates its superiority using several examples including genuine graph signals as well as conventional digital images viewed as graph signals. Furthermore, we also show how the eGHWT can be extended to 2D signals and matrix-form data by viewing them as a tensor product of graphs generated from their columns and rows and demonstrate its effectiveness on applications such as image approximation.
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FUJII, KAZUYUKI, KUNIO FUNAHASHI et TAKAYUKI KOBAYASHI. « JARLSKOG'S PARAMETRIZATION OF UNITARY MATRICES AND QUDIT THEORY ». International Journal of Geometric Methods in Modern Physics 03, no 02 (mars 2006) : 269–83. http://dx.doi.org/10.1142/s0219887806001144.
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In the paper (math–ph/0504049) Jarlskog gave an interesting simple parametrization to unitary matrices, which was essentially the canonical coordinate of the second kind in the Lie group theory (math–ph/0505047). In this paper we apply the method to a quantum computation based on multilevel system (qudit theory). Namely, by considering that the parametrization gives a complete set of modules in qudit theory, we construct the generalized Pauli matrices, which play a central role in the theory and also make a comment on the exchange gate of two–qudit systems. Moreover, we give an explicit construction to the generalized Walsh–Hadamard matrix in the case of n = 3, 4, and 5. For the case of n = 5, its calculation is relatively complicated. In general, a calculation to construct it tends to become more and more complicated as n becomes large. To perform a quantum computation the generalized Walsh–Hadamard matrix must be constructed in a quick and clean manner. From our construction it may be possible to say that a qudit theory with n ≥ 5 is not realistic. This paper is an introduction toward Quantum Engineering.
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MIYAGAWA, Isao, et Yukinobu TANIGUCHI. « Dense Light Transport for Relighting Computation Using Orthogonal Illumination Based on Walsh-Hadamard Matrix ». IEICE Transactions on Information and Systems E99.D, no 4 (2016) : 1038–51. http://dx.doi.org/10.1587/transinf.2015cyp0002.
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K, Swaraja, Meenakshi K, Ushakumari Ch et Kishore D. « A Robust image watermarking for copyright protection using Multiresolution Walsh-Hadamard transform and Schur using Differential evolution ». F1000Research 11 (16 novembre 2022) : 1333. http://dx.doi.org/10.12688/f1000research.124720.1.
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\textit{Background} The proposed watermarking framework is based on the multi-resolution Walsh-Hadamard Transform (MR-WHT) along with Schur factorization. For embedding, the cover image is converted into a frequency domain using MR-WHT before Schur factorization is applied. \textit{Methods} The upper triangle's highest stable eigenvalues in the Schur factorization are employed as reliable embedding locations for the watermark. The singular values of these coefficients are updated with the singular values of the watermark, and the matrix array generated by the biggest eigenvalues is further factorised by singular value decomposition using multiple scaling factors and Differential evolution (DE). Later, an inverse SVD, inverse Schur, and inverse multiresolution Walsh-Hadamard transform is executed to obtain a watermarked image. \textit{Results} The simulation results show that the proposed method is imperceptible and robust against existing watermarking algorithms used in the literature.
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Abdulridha, Sajjad R., et Fadhil S. Hasan. « Enhanced SLM based OFDM-DCSK communication system for PAPR reduction ». Bulletin of Electrical Engineering and Informatics 11, no 1 (1 février 2022) : 567–74. http://dx.doi.org/10.11591/eei.v11i1.3549.
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In this research, a selective mapping (SLM) technique using the Walsh Hadamard (WH) matrix, the Riemann matrix, and the new enhanced Riemann matrix were introduced to reduce the peak to average power ratio (PAPR) of orthogonal frequency division multiplexing based differential chaos shift keying (OFDM-DCSK). Using a new algorithm to reduce the size of the Riemann matrix, which in turn enhances the computational complexity of the SLM system without affecting the performance of PAPR in the main method. The simulation results show that the SLM technique using the Riemann matrix gives better PAPR performance than WH and conventional techniques by gaining about (6.3, 6.15) dB, respectively, for complementary cumulative distribution function (CCDF)=10-3 and the number of candidates U=16. Also, the results show that the SLM technique based enhanced Riemann matrix gives a reduction in computational complexity by reducing the number of candidates U to 4, while maintaining the same PAPR performance.
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Corcoran, Timothy C. « Compressive Detection of Highly Overlapped Spectra Using Walsh–Hadamard-Based Filter Functions ». Applied Spectroscopy 72, no 3 (28 novembre 2017) : 392–403. http://dx.doi.org/10.1177/0003702817738023.
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In the chemometric context in which spectral loadings of the analytes are already known, spectral filter functions may be constructed which allow the scores of mixtures of analytes to be determined in on-the-fly fashion directly, by applying a compressive detection strategy. Rather than collecting the entire spectrum over the relevant region for the mixture, a filter function may be applied within the spectrometer itself so that only the scores are recorded. Consequently, compressive detection shrinks data sets tremendously. The Walsh functions, the binary basis used in Walsh–Hadamard transform spectroscopy, form a complete orthonormal set well suited to compressive detection. A method for constructing filter functions using binary fourfold linear combinations of Walsh functions is detailed using mathematics borrowed from genetic algorithm work, as a means of optimizing said functions for a specific set of analytes. These filter functions can be constructed to automatically strip the baseline from analysis. Monte Carlo simulations were performed with a mixture of four highly overlapped Raman loadings and with ten excitation–emission matrix loadings; both sets showed a very high degree of spectral overlap. Reasonable estimates of the true scores were obtained in both simulations using noisy data sets, proving the linearity of the method.
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Liu, Li Zhao, Yu Feng Chen, Tian Hua Zhang, Ying Wang et Mao Qing Li. « Design and Implementation of Maxi-Linear Deviation Search Algorithm Based on Improved ICP ». Advanced Materials Research 143-144 (octobre 2010) : 293–97. http://dx.doi.org/10.4028/www.scientific.net/amr.143-144.293.
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To solve the problem of calculating the maximum linear deviation in block cipher algorithm linear analysis, the paper has proposed a search method and improved algorithm based on iterative closest point (ICP) of the maximum deviation. The ciphertext and its coefficient matrix is initialized as range image matrix, using ICP algorithm to calculate the best match state of adjacent range image, and the linear deviation value of round function transformation of this time was proved to be the maximum linear deviation by applying generalized Walsh spectrum; by proposing the initial rule corresponding distance, determined the initial corresponding relation of iterative algorithm, each round of transformation matrix would be assigned to the next round as the initial transformation matrix which has improved the matching speed of the ICP algorithm; the rationality and effectiveness of this new search algorithm can be proved by comparing with the maximum linear deviation search algorithm put forward by M.Matsui.
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Vose, Michael D., et Alden H. Wright. « The Simple Genetic Algorithm and the Walsh Transform : Part I, Theory ». Evolutionary Computation 6, no 3 (septembre 1998) : 253–73. http://dx.doi.org/10.1162/evco.1998.6.3.253.
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This paper is the first part of a two-part series. It proves a number of direct relationships between the Fourier transform and the simple genetic algorithm. (For a binary representation, the Walsh transform is the Fourier transform.) The results are of a theoretical nature and are based on the analysis of mutation and crossover. The Fourier transform of the mixing matrix is shown to be sparse. An explicit formula is given for the spectrum of the differential of the mixing transformation. By using the Fourier representation and the fast Fourier transform, one generation of the infinite population simple genetic algorithm can be computed in time O(cl log2 3), where c is arity of the alphabet and l is the string length. This is in contrast to the time of O(c3l) for the algorithm as represented in the standard basis. There are two orthogonal decompositions of population space that are invariant under mixing. The sequel to this paper will apply the basic theoretical results obtained here to inverse problems and asymptotic behavior.
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Denisov, А., Y. Denisov, O. Bursala et O. Bursala. « CONTROL OF WORKING BODY OF AIRBORNE AIRCRAFT POSITIONING MECHANISMS BY MEANS OF STEPPER MOTOR IN STEP CRUSHING MODE ». Наукові праці Державного науково-дослідного інституту випробувань і сертифікації озброєння та військової техніки, no 12 (5 juillet 2022) : 41–52. http://dx.doi.org/10.37701/dndivsovt.12.2022.05.
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Step splitting control mode of the electric drives stepper motors working bodies of the positioning mechanisms of onboard aviation equipment is carried out by means of programmable controllers. From their output signals, pulse-wide signals are formed by means of drivers that control power transistors, which are included in the windings of a stepper motor.
A simpler version of building control systems for stepper motors (SM) involves the use of programmable timers, which requires its reprogramming when changing the step splitting factor.
In the process of step splitting the shape of the current in the winding of the SM approaches sinusoidal with an increase in the number of sine discretes stored in the controller's memory. However, in this case, the sine samples must follow at a higher frequency, which difficulties in programming them.
There is a problem of finding new ways of programming in the controller's memory information about the changing shape of the supply voltage SM in the process of step splitting in order to ensure the maximum speed of the code and the minimum consumption of the processor time of the microcontroller.
To solve this problem, it is proposed to specify information about the changing shape of the SM supply voltage not in the form of sine samples (table method), but the sum of the coefficients of the Walsh-Fourier series, the amplitudes of which depend of value of the step splitting factor.
The Walsh-Fourier series is a natural basis for approximating the pulsed supply voltage of a stepper motor. Structural diagrams of digital and analog systems for stepper motors in the step splitting are proposed.
In the digital control system, the Walsh matrix is entered into the permanent memory of the controller, the size of which is determined by the value of the minimum step splitting factor, and the column vectors of the coefficients of the amplitudes of the Walsh functions are entered into the random-access memory, each of which corresponds to its step splitting factor.
The input controller sets the program for implementing the inverse Walsh transform to the control controller, as a result of which control signals for the driver are generated at the output of the DAC controller. As its output, control signals are generated for power transistors including in the windings of the stepper motor.
In the analog control system, the main links are the Walsh functions generator and the block of summing coefficients. In the block of summing coefficients of each Walsh function is assigned an amplitude corresponding to a given step splitting factor, and then they are summed. As a result, a pulsed voltage is formed, which is fed to the input of the driver, as in a digital system. It is shown that an analog control system can be used to form low-frequency quasi- sine signals of high stability. They can be used in precision electric drives with high stability.
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LEE, HAIYOUNG, et ZEUNGNAM BIEN. « Method of computing the inverse of a matrix whose elements are a linear combination of Walsh functions ». International Journal of Control 47, no 5 (mai 1988) : 1235–42. http://dx.doi.org/10.1080/00207178808906091.
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JIANG, Z. H. « New method for computing the inverse of a matrix whose elements are linear combinations of Walsh functions ». International Journal of Systems Science 20, no 11 (novembre 1989) : 2335–40. http://dx.doi.org/10.1080/00207728908910311.
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Bykov, V. N., G. Yu Miroshnik et T. V. Miroshnik. « Evaluation of accuracy of radiometric correlation-extreme navigation systems ». 34, no 34 (30 juin 2021) : 7–13. http://dx.doi.org/10.26565/2311-0872-2021-34-01.
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Background: The use of passive matrix radiometric sensors of the millimeter wave range in aircraft navigation systems, which make it possible to form a radiometric image of a ground navigation object under conditions of high-speed flight of aircraft, is one of the effective ways to ensure high accuracy in measuring the coordinates of objects and, ultimately, leads to an increase in the probability of positioning aircraft [1]. In work [2], analytical relationships were obtained and quantitative estimates of the accuracy of positioning of aircraft equipped with a matrix radiometric navigation system were made. It is shown that the use of matrix radiometric sensors makes it possible to realize the required high (up to units - tens of meters) positioning accuracy of high-speed aircraft. Objectives: The purpose of this article is to develop a method for increasing the accuracy of a radiometric correlation - extreme system based on the use of a matrix radiometric millimeter-wave receiver with channel compaction. Materials and methods: In this paper, we used the method of linear multiplexing with channel separation according to the waveform using orthogonal Walsh functions. In this case, the sensitivity for each channel corresponds to the sensitivity of the modulation radiometer, and in comparison with the sensitivity of the compensation radiometer, it decreases by about two times. Taking into account the orthonormality of the Walsh functions, the signal at the output of each channel is proportional to the intensity (power) of the signal at the input of this channel. Results: In this work, it is shown that the optimal number of combined channels is a multiple . The analysis of the results of the calculations shows that the combination of 64 channels into one amplifier-conversion path leads to an increase in inter-channel interference and, as a consequence, to a deterioration in the sensitivity of each channel. Conclusions: In this case, it is expedient to limit the number of channels to be sealed per one amplifying-converting path. So, when 16 channels are combined into one path, the sensitivity of each channel remains quite high: about 1 K – for a super heterodyne radiometric receiver, and less than 1 K – for a direct amplification radiometric receiver. In this case, the number of amplifying-conversion paths with the total number of channels in the matrix 64 is equal to four.
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Tohidi, Emran, F. Soleymani et Adem Kilicman. « Robustness of Operational Matrices of Differentiation for Solving State-Space Analysis and Optimal Control Problems ». Abstract and Applied Analysis 2013 (2013) : 1–9. http://dx.doi.org/10.1155/2013/535979.
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The idea of approximation by monomials together with the collocation technique over a uniform mesh for solvingstate-space analysisandoptimal controlproblems (OCPs) has been proposed in this paper. After imposing the Pontryagins maximum principle to the main OCPs, the problems reduce to a linear or nonlinear boundary value problem. In the linear case we propose a monomial collocation matrix approach, while in the nonlinear case, the general collocation method has been applied. We also show the efficiency of the operational matrices of differentiation with respect to the operational matrices of integration in our numerical examples. These matrices of integration are related to the Bessel, Walsh, Triangular, Laguerre, and Hermite functions.
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WANG, Yulong, et Ji REN. « WHIT : A More Efficient Hybrid Method for Single-Packet IP Traceback Using Walsh Matrix and Router Degree Distribution ». IEICE Transactions on Communications E96.B, no 7 (2013) : 1896–907. http://dx.doi.org/10.1587/transcom.e96.b.1896.
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Zinde-Walsh, Victoria. « Errata ». Econometric Theory 6, no 2 (juin 1990) : 293. http://dx.doi.org/10.1017/s0266466600005259.
Texte intégralRésumé :
There are some errors in the paper by Victoria Zinde-Walsh, “Some Exact Formulae for Autoregressive Moving Average Processes,” Econometric Theory 4 (1988): 384–402. The following is a list of corrections.On page 393 the τ * τ matrices El,E2 should be replaced by their transposes ,, respectively, throughout. In (3.21) the expression (S3 – λλA3) should be replaced by (S3 – λλA3) in the definitions of both T1, and T3. In (3.8), (3.21), (5.1), and (5.2) the entry in the bottom right-hand corner should be pre- and post-multiplied by λ. In (3.6) the matrix is obtained as the negative of the matrix denoted in the previous section 3.1. In (3.19) the top bar was omitted in Ē2. The top bar was also omitted in Ē1 on the second to last line of p. 392. In (5.1) D′−1 rather than D−l should appear in all the matrix entries in the second column; D′−1 should premultiply the parentheses in the top left and bottom right corners instead of D−1 post-multiplying them. In (5.2) transposes were omitted on D in the second entries on the first and last lines; in the second line of the second column, the second time A2 appears it should be transposed.
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Dziech, Andrzej. « New Orthogonal Transforms for Signal and Image Processing ». Applied Sciences 11, no 16 (12 août 2021) : 7433. http://dx.doi.org/10.3390/app11167433.
Texte intégralRésumé :
In the paper, orthogonal transforms based on proposed symmetric, orthogonal matrices are created. These transforms can be considered as generalized Walsh–Hadamard Transforms. The simplicity of calculating the forward and inverse transforms is one of the important features of the presented approach. The conditions for creating symmetric, orthogonal matrices are defined. It is shown that for the selection of the elements of an orthogonal matrix that meets the given conditions, it is necessary to select only a limited number of elements. The general form of the orthogonal, symmetric matrix having an exponential form is also presented. Orthogonal basis functions based on the created matrices can be used for orthogonal expansion leading to signal approximation. An exponential form of orthogonal, sparse matrices with variable parameters is also created. Various versions of orthogonal transforms related to the created full and sparse matrices are proposed. Fast computation of the presented transforms in comparison to fast algorithms of selected orthogonal transforms is discussed. Possible applications for signal approximation and examples of image spectrum in the considered transform domains are presented.
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VIJAYAKUMAR, ASHA, et G. ABHILASH. « SIMPLE STRUCTURES FOR UNIMODULAR FILTER BANKS WITH REGULARITY ». Journal of Circuits, Systems and Computers 17, no 03 (juin 2008) : 353–63. http://dx.doi.org/10.1142/s0218126608004447.
Texte intégralRésumé :
In this paper we propose two new parameterizations for unimodular filter banks (UMFBs) by exploiting the canonical forms of the nilpotent matrix present in the factorization of UMFBs. A judicious choice of the canonical structure leads to simple implementation. The use of Discrete Walsh Hadamard Transform (DWHT) saves a major amount of multiplication. The presence of the nilpotent matrix also facilitates the design of filter banks with unequal length analysis and synthesis filters. The structures ensure perfect reconstruction (PR) with minimal delay in the McMillan sense. The free parameters can be obtained through unconstrained optimization, which is hardly possible with the existing design methods. Design examples are presented based on the proposed structures. Although there is a significant reduction in the number of free parameters, the performances of these structures are found to be comparable with and better than the existing design techniques for UMFBs. The design of a class of decomposable higher order UMFBs with unequal lengths of analysis and synthesis filters is done. Also, the design of a one-regular filter bank based on the simplest structure proposed is presented.
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Rybakov, Konstantin. « Spectral representation of stochastic integration operators ». MATEC Web of Conferences 362 (2022) : 01027. http://dx.doi.org/10.1051/matecconf/202236201027.
Texte intégralRésumé :
The spectral representation for stochastic integration operators with respect to the Wiener process is proposed in the form of a composition of spectral characteristics used in the spectral form of mathematical description for control systems. This spectral representation can be defined relative to the various orthonormal bases. For given deterministic square-integrable kernels, the spectral characteristic of a stochastic integration operator is determined as an infinite random matrix. The main applications of such a representation suppose solving linear stochastic differential equations and modeling multiple or iterated Stratonovich stochastic integrals. Specific formulas are provided that allow to represent the spectral characteristic for the stochastic integration operator, the kernel of which is the Heaviside function, relative to Walsh functions and trigonometric functions.
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Zghair, Hayder Kadhim, Hussein Ali Ismael et Ameer Al-Haq Al-Shamery. « Image scrambler based on novel 4-D hyperchaotic system and magic square with fast Walsh–Hadamard transform ». Bulletin of Electrical Engineering and Informatics 11, no 6 (1 décembre 2022) : 3530–38. http://dx.doi.org/10.11591/eei.v11i6.4339.
Texte intégralRésumé :
A novel 4-D hyperchaotic system that have seven positive parameters in third order with thirteen terms is proposed,in this paper, the proposed chaotic behavior is proved by analysis of the Lyapunov's exponent, fractional dimension, zero-one test, sensitivity dependent on initial condition (SDIC), phase portraits, and waveform analysis, this study offers an innovative designed image encryption algorithm depending on a 4-D chaotic system using fast discrete Walsh-Hadamard transform and magic matrix that is both effective and simple for image encryption and gives it a higher level of security. This new 4-D hyperchaotic system is used to produce a random key in this algorithm. The implemented and simulated results using mathematica programs and MATLAB programs were supplied qualitatively and in figures. The proposed system is hyperchaotic, according to testing results, because it possesses two Lyapunov positive exponents.
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Rowe, Jonathan E., Michael D. Vose et Alden H. Wright. « Structural Search Spaces and Genetic Operators ». Evolutionary Computation 12, no 4 (décembre 2004) : 461–93. http://dx.doi.org/10.1162/1063656043138941.
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In a previous paper (Rowe et al., 2002), aspects of the theory of genetic algorithms were generalised to the case where the search space, Ω, had an arbitrary group action defined on it. Conditions under which genetic operators respect certain subsets of Ω were identified, leading to a generalisation of the termschema. In this paper, search space groups with more detailed structure are examined. We define the class of structural crossover operators that respect certain schemata in these groups, which leads to a generalised schema theorem. Recent results concerning the Fourier (or Walsh) transform are generalised. In particular, it is shown that the matrix group representing Ω can be simultaneously diagonalised if and only if Ω is Abelian. Some results concerning structural crossover and mutation are given for this case.
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GAUBERT, STÉPHANE, et GUILLAUME VIGERAL. « A maximin characterisation of the escape rate of non-expansive mappings in metrically convex spaces ». Mathematical Proceedings of the Cambridge Philosophical Society 152, no 2 (19 octobre 2011) : 341–63. http://dx.doi.org/10.1017/s0305004111000673.
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AbstractWe establish a maximin characterisation of the linear escape rate of the orbits of a non-expansive mapping on a complete (hemi-)metric space, under a mild form of Busemann's non-positive curvature condition (we require a distinguished family of geodesics with a common origin to satisfy a convexity inequality). This characterisation, which involves horofunctions, generalises the Collatz–Wielandt characterisation of the spectral radius of a non-negative matrix. It yields as corollaries a theorem of Kohlberg and Neyman (1981), concerning non-expansive maps in Banach spaces, a variant of a Denjoy–Wolff type theorem of Karlsson (2001), together with a refinement of a theorem of Gunawardena and Walsh (2003), concerning order-preserving positively homogeneous self-maps of symmetric cones. An application to zero-sum stochastic games is also given.
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Lei, Zijian, et Liang Lan. « Improved Subsampled Randomized Hadamard Transform for Linear SVM ». Proceedings of the AAAI Conference on Artificial Intelligence 34, no 04 (3 avril 2020) : 4519–26. http://dx.doi.org/10.1609/aaai.v34i04.5880.
Texte intégralRésumé :
Subsampled Randomized Hadamard Transform (SRHT), a popular random projection method that can efficiently project a d-dimensional data into r-dimensional space (r ≪ d) in O(dlog(d)) time, has been widely used to address the challenge of high-dimensionality in machine learning. SRHT works by rotating the input data matrix X ∈ ℝn × d by Randomized Walsh-Hadamard Transform followed with a subsequent uniform column sampling on the rotated matrix. Despite the advantages of SRHT, one limitation of SRHT is that it generates the new low-dimensional embedding without considering any specific properties of a given dataset. Therefore, this data-independent random projection method may result in inferior and unstable performance when used for a particular machine learning task, e.g., classification. To overcome this limitation, we analyze the effect of using SRHT for random projection in the context of linear SVM classification. Based on our analysis, we propose importance sampling and deterministic top-r sampling to produce effective low-dimensional embedding instead of uniform sampling SRHT. In addition, we also proposed a new supervised non-uniform sampling method. Our experimental results have demonstrated that our proposed methods can achieve higher classification accuracies than SRHT and other random projection methods on six real-life datasets.
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MAJEED, Alyaa M. Abdul. « A NOVEL METHOD FOR GENERATING DIGITAL IMAGE OF ENCRYPTED SPEECH SIGNAL BASED ON FWHT AND WPLCM ». MINAR International Journal of Applied Sciences and Technology 03, no 04 (1 décembre 2021) : 35–46. http://dx.doi.org/10.47832/2717-8234.4-3.5.
Texte intégralRésumé :
This paper suggests a novel algorithm for encrypting speech signals in common image formats and retrieve them from these image files. The speech signal is encrypted in three levels. In the first level,the sample positions are permuted based on keys generated using Game of Life matrix and Piecewise linear Chaotic Map (PWLCM) in order to reduce the correlation between adjust samples. In the second level, the resulting samples are then converted to Fast Walsh Hadamard Transform (FWHT) and their transactions are encrypted by using circular transformations in the row and column depending on the generated key. At the third level, the values of encrypted samples are converted to color pixels, which are then arranged in a puzzled manner and put in a 2-D matrix to achieve the secured data transfer across networks, with the image file contains the encrypted speech signal. Several objective measures have been used to evaluate the performance of the suggested method. The experimental results and numerical analyses show that the algorithm gives a high degree of security and robust against brute force attackers, statistical attack, strong diffusion and ambiguity so that the encrypted message has been saved in a different format from the original signal, and finally give the good quality of the reconstructed speech signal from image files.
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Abdulwali, Jummah, et Said Boussakta. « Visible Light Communication : An Investigation of LED Non-Linearity Effects on VLC Utilising C-OFDM ». Photonics 9, no 3 (17 mars 2022) : 192. http://dx.doi.org/10.3390/photonics9030192.
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The electro-optic output of light-emitting diodes commonly used in visible light communication systems is generally nonlinear in nature. It is particularly problematic when using advanced modulation formats, such as orthogonal frequency-division multiplexing (OFDM), which have a high peak-to-average power ratio due to clipping and distortion. In this work, we introduce the so-called C-transform to the system architecture, which utilises a Walsh–Hadamard matrix in conjunction with a discrete cosine transform to deterministically spread the information and reduce the peak-to-average power ratio (PAPR). Several bias points along the electro-optic transfer function were selected for comparison purposes, and the new transform was compared with more traditional formulations of OFDM. This paper determines that the C-transform-based OFDM demonstrated the highest degree of independence from the non-linearity and yielded superior bit-error rate (BER) results. We note an improvement of ~2.5 dB in the power penalty at a BER of 10−4 in comparison to OFDM.
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Beknazarova, Saida, Mexriban Jaumitbayeva, Doston Xamroyev et Shaxboz Musirmonov. « METHOD OF FILTERING DIGITAL IMAGES BY PULSE CHARACTERISTIC IN THE SPECTRAL REGION ». Актуальные вопросы развития инновационно-информационных технологий на транспорте 1, no 1 (6 avril 2022) : 66–69. http://dx.doi.org/10.47689/978-9943-7818-0-1-pp66-69.
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In the world, scientific research is being conducted to improve the quality level of digital television images, methods for modeling filtration processes and highly efficient control systems in a number of priority areas, including: on the formation of mathematical models of filtration processes, improving the methods of wavelet, Fourier, Haar, Walsh-Hadamard, Karhunen-Loev in increasing the clarity and brightness of images based on linear and nonlinear differential equations; creation of methods for eliminating additive, pulsed and adaptive-Gaussian types of noise in images using additive and adaptive filtering; methods of algorithms and software for introducing intra-frame and inter-frame image transformations; methods of adaptive brightness system control using the Chebyshev matrix series; methods of gradient, static and Laplace methods for image segmentation and dividing it into contours; formation of criteria and conditions for evaluating image quality. Conducting scientific research in the above research areas confirms the relevance of the topic of this article.
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Pan, Jie, Li-Ping Li, Chang-Qing Yu, Zhu-Hong You, Zhong-Hao Ren et Jing-Yu Tang. « FWHT-RF : A Novel Computational Approach to Predict Plant Protein-Protein Interactions via an Ensemble Learning Method ». Scientific Programming 2021 (22 juillet 2021) : 1–11. http://dx.doi.org/10.1155/2021/1607946.
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Protein-protein interactions (PPIs) in plants are crucial for understanding biological processes. Although high-throughput techniques produced valuable information to identify PPIs in plants, they are usually expensive, inefficient, and extremely time-consuming. Hence, there is an urgent need to develop novel computational methods to predict PPIs in plants. In this article, we proposed a novel approach to predict PPIs in plants only using the information of protein sequences. Specifically, plants’ protein sequences are first converted as position-specific scoring matrix (PSSM); then, the fast Walsh–Hadamard transform (FWHT) algorithm is used to extract feature vectors from PSSM to obtain evolutionary information of plant proteins. Lastly, the rotation forest (RF) classifier is trained for prediction and produced a series of evaluation results. In this work, we named this approach FWHT-RF because FWHT and RF are used for feature extraction and classification, respectively. When applying FWHT-RF on three plants’ PPI datasets Maize, Rice, and Arabidopsis thaliana (Arabidopsis), the average accuracies of FWHT-RF using 5-fold cross validation were achieved as high as 95.20%, 94.42%, and 83.85%, respectively. To further evaluate the predictive power of FWHT-RF, we compared it with the state-of-art support vector machine (SVM) and K-nearest neighbor (KNN) classifier in different aspects. The experimental results demonstrated that FWHT-RF can be a useful supplementary method to predict potential PPIs in plants.
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Dai, Wanying, Xiangliang Xu, Xiaoming Song et Guodong Li. « Audio Encryption Algorithm Based on Chen Memristor Chaotic System ». Symmetry 14, no 1 (23 décembre 2021) : 17. http://dx.doi.org/10.3390/sym14010017.
Texte intégralRésumé :
The data space for audio signals is large, the correlation is strong, and the traditional encryption algorithm cannot meet the needs of efficiency and safety. To solve this problem, an audio encryption algorithm based on Chen memristor chaotic system is proposed. The core idea of the algorithm is to encrypt the audio signal into the color image information. Most of the traditional audio encryption algorithms are transmitted in the form of noise, which makes it easy to attract the attention of attackers. In this paper, a special encryption method is used to obtain higher security. Firstly, the Fast Walsh–Hadamar Transform (FWHT) is used to compress and denoise the signal. Different from the Fast Fourier Transform (FFT) and the Discrete Cosine Transform (DCT), FWHT has good energy compression characteristics. In addition, compared with that of the triangular basis function of the Fast Fourier Transform, the rectangular basis function of the FWHT can be more effectively implemented in the digital circuit to transform the reconstructed dual-channel audio signal into the R and B layers of the digital image matrix, respectively. Furthermore, a new Chen memristor chaotic system solves the periodic window problems, such as the limited chaos range and nonuniform distribution. It can generate a mask block with high complexity and fill it into the G layer of the color image matrix to obtain a color audio image. In the next place, combining plaintext information with color audio images, interactive channel shuffling can not only weaken the correlation between adjacent samples, but also effectively resist selective plaintext attacks. Finally, the cryptographic block is used for overlapping diffusion encryption to fill the silence period of the speech signal, so as to obtain the ciphertext audio. Experimental results and comparative analysis show that the algorithm is suitable for different types of audio signals, and can resist many common cryptographic analysis attacks. Compared with that of similar audio encryption algorithms, the security index of the algorithm is better, and the efficiency of the algorithm is greatly improved.
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Awan, Muhammad Tayyib, Muhammad Amir, Sarmad Maqsood, Musyyab Yousufi, Suheel Abdullah et MUHAMMAD IRFAN. « Modified Block Compressed Sensing for Extraction of Fetal Electrocardiogram from Mother Electrocardiogram Using Block Compressed Sensing Based Guided FOCUSS and FAST-Independent Component ». Information Technology and Control 50, no 1 (25 mars 2021) : 123–37. http://dx.doi.org/10.5755/j01.itc.50.1.24145.
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Fetal ECG extraction from abdominal ECG is critical task for telemonitoring of fetus which require lot of understanding to the subject. Conventional source separation methods are not efficient enough to separate FECG from huge multichannel ECG. Thus use of compression technique is needed to compress and reconstruct ECG signal without any significant losses in quality of signal. Compressed sensing shows promising results for such tasks. However, current compressed sensing theory is not so far that successful due to the non-sparsity and strong noise contamination present in ECG signal. The proposed work explores the concept of block compressed sensing to reconstruct non-sparse FECG signal using GFOCUSS algorithm. The main objective of this paper is not only to successfully reconstruct the ECG signal but to efficiently separate FECG from abdominal ECG. The proposed algorithm is explained in very extensive manner for all experiments. The key feature of proposed method is, that it doesn’t affect the interdependence relation between multichannel ECG. The useof walsh sensing matrix made it possible to achieve high compression ratio. Experimental results shows that even at very high compression ratio, successful FECG reconstruction from raw ECG is possible. These results are validated using PSNR, SINR, and MSE. This shows the framework, compared to other algorithms such as current blocking CS algorithms, rackness CS algorithm and wavelet algorithms, can greatly reduce code execution time during data compression stage and achieve better reconstruction in terms of MSE, PSNR and SINR.
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Kountchev, Roumen, Rumen Mironov et Roumiana Kountcheva. « Complexity Estimation of Cubical Tensor Represented through 3D Frequency-Ordered Hierarchical KLT ». Symmetry 12, no 10 (26 septembre 2020) : 1605. http://dx.doi.org/10.3390/sym12101605.
Texte intégralRésumé :
In this work is introduced one new hierarchical decomposition for cubical tensor of size 2n, based on the well-known orthogonal transforms Principal Component Analysis and Karhunen–Loeve Transform. The decomposition is called 3D Frequency-Ordered Hierarchical KLT (3D-FOHKLT). It is separable, and its calculation is based on the one-dimensional Frequency-Ordered Hierarchical KLT (1D-FOHKLT) applied on a sequence of matrices. The transform matrix is the product of n sparse matrices, symmetrical at the point of their main diagonal. In particular, for the case in which the angles which define the transform coefficients for the couples of matrices in each hierarchical level of 1D-FOHKLT are equal to π/4, the transform coincides with this of the frequency-ordered 1D Walsh–Hadamard. Compared to the hierarchical decompositions of Tucker (H-Tucker) and the Tensor-Train (TT), the offered approach does not ensure full decorrelation between its components, but is close to the maximum. On the other hand, the evaluation of the computational complexity (CC) of the new decomposition proves that it is lower than that of the above-mentioned similar approaches. In correspondence with the comparison results for H-Tucker and TT, the CC decreases fast together with the increase of the hierarchical levels’ number, n. An additional advantage of 3D-FOHKLT is that it is based on the use of operations of low complexity, while the similar famous decompositions need large numbers of iterations to achieve the coveted accuracy.
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Ali B H, Baba Fakruddin, et Prakash Ramachandran. « Compressive Domain Deep CNN for Image Classification and Performance Improvement Using Genetic Algorithm-Based Sensing Mask Learning ». Applied Sciences 12, no 14 (7 juillet 2022) : 6881. http://dx.doi.org/10.3390/app12146881.
Texte intégralRésumé :
The majority of digital images are stored in compressed form. Generally, image classification using convolution neural network (CNN) is done in uncompressed form rather than compressed one. Training the CNN in the compressed domain eliminates the requirement for decompression process and results in improved efficiency, minimal storage, and lesser cost. Compressive sensing (CS) is one of the effective and efficient method for signal acquisition and recovery and CNN training on CS measurements makes the entire process compact. The most popular sensing phenomenon used in CS is based on image acquisition using single pixel camera (SPC) which has complex design implementation and usually a matrix simulation is used to represent the SPC process in numerical demonstration. The CS measurements using this phenomenon are visually different from the image and to add this in the training set of the compressed learning framework, there is a need for an inverse SPC process that is to be applied all through the training and testing dataset image samples. In this paper we proposed a simple sensing phenomenon which can be implemented using the image output of a standard digital camera by retaining few pixels and forcing the rest of the pixels to zero and this reduced set of pixels is assumed as CS measurements. This process is modeled by a binary mask application on the image and the resultant image still subjectively legible for human vision and can be used directly in the training dataset. This sensing mask has very few active pixels at arbitrary locations and there is a lot of scope to heuristically learn the sensing mask suitable for the dataset. Only very few attempts had been made to learn the sensing matrix and the sole effect of this learning process on the improvement of CNN model accuracy is not reported. We proposed to have an ablation approach to study how this sensing matrix learning improves the accuracy of the basic CNN architecture. We applied CS for two class image dataset by applying a Primitive Walsh Hadamard (PWH) binary mask function and performed the classification experiment using a basic CNN. By retaining arbitrary amount of pixel in the training and testing dataset we applied CNN on the compressed measurements to perform image classification and studied and reported the model performance in terms of training and validation accuracies by varying the amount of pixels retained. A novel Genetic Algorithm-based compressive learning (GACL) method is proposed to learn the PWH mask to optimize the model training accuracy by using two different crossover techniques. In the experiment conducted for the case of compression ratio (CR) 90% by retaining only 10% of the pixels in every images both in training and testing dataset that represent two classes, the training accuracy is improved from 67% to 85% by using diagonal crossover in offspring creation of GACL. The robustness of the method is examined by applying GACL for user defined multiclass dataset and achieved better CNN model accuracies. This work will bring out the strength of sensing matrix learning which can be integrated with advanced training models to minimize the amount of information that is to be sent to central servers and will be suitable for a typical IoT frame work.
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Dieffenbach, Paul B., Christina Mallarino Haeger, Anna Maria F. Coronata, Kyoung Moo Choi, Xaralabos Varelas, Daniel J. Tschumperlin et Laura E. Fredenburgh. « Arterial stiffness induces remodeling phenotypes in pulmonary artery smooth muscle cells via YAP/TAZ-mediated repression of cyclooxygenase-2 ». American Journal of Physiology-Lung Cellular and Molecular Physiology 313, no 3 (1 septembre 2017) : L628—L647. http://dx.doi.org/10.1152/ajplung.00173.2017.
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Pulmonary arterial stiffness is an independent risk factor for mortality in pulmonary hypertension (PH) and plays a critical role in PH pathophysiology. Our laboratory has recently demonstrated arterial stiffening early in experimental PH, along with evidence for a mechanobiological feedback loop by which arterial stiffening promotes further cellular remodeling behaviors (Liu F, Haeger CM, Dieffenbach PB, Sicard D, Chrobak I, Coronata AM, Suárez Velandia MM, Vitali S, Colas RA, Norris PC, Marinković A, Liu X, Ma J, Rose CD, Lee SJ, Comhair SA, Erzurum SC, McDonald JD, Serhan CN, Walsh SR, Tschumperlin DJ, Fredenburgh LE. JCI Insight 1: e86987, 2016). Cyclooxygenase-2 (COX-2) and prostaglandin signaling have been implicated in stiffness-mediated regulation, with prostaglandin activity inversely correlated to matrix stiffness and remodeling behaviors in vitro, as well as to disease progression in rodent PH models. The mechanism by which mechanical signaling translates to reduced COX-2 activity in pulmonary vascular cells is unknown. The present work investigated the transcriptional regulators Yes-associated protein (YAP) and WW domain-containing transcription regulator 1 (WWTR1, a.k.a., TAZ), which are known drivers of downstream mechanical signaling, in mediating stiffness-induced changes in COX-2 and prostaglandin activity in pulmonary artery smooth muscle cells (PASMCs). We found that YAP/TAZ activity is increased in PAH PASMCs and experimental PH and is necessary for the development of stiffness-dependent remodeling phenotypes. Knockdown of YAP and TAZ markedly induces COX-2 expression and downstream prostaglandin production by approximately threefold, whereas overexpression of YAP or TAZ reduces COX-2 expression and prostaglandin production to near undetectable levels. Together, our findings demonstrate a stiffness-dependent YAP/TAZ-mediated positive feedback loop that drives remodeling phenotypes in PASMCs via reduced COX-2 and prostaglandin activity. The ability to interrupt this critical mechanobiological feedback loop and enhance local prostaglandin activity via manipulation of YAP/TAZ signaling presents a highly attractive novel strategy for the treatment of PH.
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Stopka, Tomas, Karin Vargova, Juraj Kokavec, Vit Pospisil, Nikola Curik, Pavel Burda, Arthur I. Skoultchi et Jiri Zavadil. « Mutual Regulatory Loop between miR-155 and PU.1 Is a Candidate Pathogenesis Factor in CLL. » Blood 110, no 11 (16 novembre 2007) : 1130. http://dx.doi.org/10.1182/blood.v110.11.1130.1130.
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Abstract MicroRNAs are non-coding post-transcriptional regulators of gene expression often dysregulated in human cancers including hematological malignancies. MiR-155 is a putative oncogenic factor found overexpressed in chronic lymphocytic leukemia (CLL) cells. We have confirmed the increased levels of miR-155 in peripheral blood lymphocytes in 12 patients with chronic lymphocytic leukemia (CLL) compared to 11 normal controls, using quantitative PCR assay. Among the predicted high-scoring hematopoietic target genes of miR-155 is the ets-family transcription factor PU.1, a key regulator of myelo-lymphoid lineage development. Using gene expression profiling of CLL peripheral lymphocyte samples compared to normal controls, we have determined significant downregulation of the PU.1 mRNA and of additional numerous miR-155 targets previously reported to be required for myelo-lymphoid differentiation, and of a set of gene targets of PU.1-chromatin DNA interactions that we determined by chromatin immunoprecipitation analyses. Functional pathway analysis of the miR-155 targets downregulated in CLL patients suggest the suppression of T-cell receptor pathway, TGF-b/Bmp, MAPK, Jak/Stat and Wnt signaling and remodeling of actin cytoskeleton and cell-matrix interactions, as well as the regulation of numerous transcription regulators including c-FOS, c-MYC, MAFB and HDAC4. Recent reports suggested a role of miR-155 in lymphocytic differentiation, we have tested whether PU.1 may regulate expression of its own regulator miR-155. We used two cell systems expressing a transgene encoding PU.1 fused with the ligand binding domain of the estrogen receptor, ER): murine erythroleukemia (MEL) cells (Rao 1997) and PU.1 null hematopoietic progenitor cells stably transfected with PU.1-ER (Walsh 2002). Using a miRNA microarray assay we have identified a set of 21 miRNAs that are modulated by PU.1. Indeed, miR-155 was among the upregulated targets alongside a known PU.1 miR target miR-233. The direct interaction between miR-155 promoter and PU.1 protein was confirmed by chromatin immunoprecipitation in MEL cells. In summary, our data suggests that increased miR-155 levels may contribute to CLL by inhibiting PU.1 function and suppressing PU.1-mediated programs and that in two independent conditional PU.1 cell systems PU.1 directly binds miR-155 promoter and upregulates its expression suggesting thus a mutual regulatory mechanism between PU.1 and miR-155.