136 results about "Circulant matrix" patented technology

An iterative image reconstruction method used with an imaging system that generates projection data, the method comprises: collecting the projection data; choosing a polar or cylindrical image definition comprising a polar or cylindrical grid representation and a number of basis functions positioned according to the polar or cylindrical grid so that the number of basis functions at different radius positions of the polar or cylindrical image grid is a factor of a number of in-plane symmetries between lines of response along which the projection data are measured by the imaging system; obtaining a system probability matrix that relates each of the projection data to each basis function of the polar or cylindrical image definition; restructuring the system probability matrix into a block circulant matrix and converting the system probability matrix in the Fourier domain; storing the projection data into a measurement data vector; providing an initial polar or cylindrical image estimate; for each iteration; recalculating the polar or cylindrical image estimate according to an iterative solver based on forward and back projection operations with the system probability matrix in the Fourier domain; and converting the polar or cylindrical image estimate into a Cartesian image representation to thereby obtain a reconstructed image.

An automated tuning method of a large-scale multivariable model predictive controller for multiple array papermaking machine cross-directional (CD) processes can significantly improve the performance of the controller over traditional controllers. Paper machine CD processes are large-scale spatially-distributed dynamical systems. Due to these systems' (almost) spatially invariant nature, the closed-loop transfer functions are approximated by transfer matrices with rectangular circulant matrix blocks, whose input and output singular vectors are the Fourier components of dimension equivalent to either number of actuators or number of measurements. This approximation enables the model predictive controller for these systems to be tuned by a numerical search over optimization weights in order to shape the closed-loop transfer functions in the two-dimensional frequency domain for performance and robustness. A novel scaling method is used for scaling the inputs and outputs of the multivariable system in the spatial frequency domain.

Encoding of a low-density parity check code uses a block-circulant encoding matrix built from circulant matrices. Encoding can include partitioning data into a plurality of data segments. The data segments are each circularly rotated. A plurality of XOR summations are formed for each rotation of the data segments to produce output symbols. The XOR summations use data from the data segments defined by the circulant matrices. Output symbols are produced in parallel for each rotation of the data segments.

Multi-Input-Multi-Output (MIMO) Optimal Decision Feedback Equalizer (DFE) coefficients are determined from a channel estimate h by casting the MIMO DFE coefficient problem as a standard recursive least squares (RLS) problem and solving the RLS problem. In one embodiment, a fast recursive method, e.g., fast transversal filter (FTF) technique, then used to compute the Kalman gain of the RLS problem, which is then directly used to compute MIMO Feed Forward Equalizer (FFE) coefficients gopt. The complexity of a conventional FTF algorithm is reduced to one third of its original complexity by choosing the length of a MIMO Feed Back Equalizer (FBE) coefficients bopt (of the DFE) to force the FTF algorithm to use a lower triangular matrix. The MIMO FBE coefficients bop are computed by convolving the MIMO FFE coefficients gopt with the channel impulse response h. In performing this operation, a convolution matrix that characterizes the channel impulse response h extended to a bigger circulant matrix. With the extended circulant matrix structure, the convolution of the MIMO FFE coefficients gopt with the channel impulse response h may be performed easily performed in the frequency domain.

A regular quasi-cyclic matrix is generated with cyclic permutation matrices and specific regularity given to the cyclic permutation matrices. A mask matrix for making the regular quasi-cyclic matrix into an irregular quasi-cyclic matrix is generated. An irregular masked quasi-cyclic matrix is generated by converting a specific cyclic permutation matrix in the regular quasi-cyclic matrix into a zero-matrix using a mask matrix supporting a specific encoding rate. An irregular parity check matrix with an LDGM structure is generated with a masked quasi-cyclic matrix and a matrix in which the cyclic permutation matrices are arranged in a staircase manner.

A transmitter may map, using a selected modulation constellation, each of C′ bit sequences to a respective one of C′ symbols, where C′ is a number greater than one. The transmitter may process the C′ symbols to generate C′ inter-carrier correlated virtual subcarrier values. The transmitter may decimate the C′ virtual subcarrier values down to C physical subcarrier values, C being a number less than C′. The transmitter may transmit the C physical subcarrier values on C orthogonal frequency division multiplexed (OFDM) subcarriers. The modulation constellation may be an N-QAM constellation, where N is an integer. The processing may comprise filtering the C′ symbols using an array of C′ filter tap coefficients. The filtering may comprise cyclic filtering. The filtering may comprise multiplication by a circulant matrix populated with the C′ filter tap coefficients.

An iterative image reconstruction method used with an imaging system that generates projection data, the method comprises: collecting the projection data; choosing a polar or cylindrical image definition comprising a polar or cylindrical grid representation and a number of basis functions positioned according to the polar or cylindrical grid so that the number of basis functions at different radius positions of the polar or cylindrical image grid is a factor of a number of in-plane symmetries between lines of response along which the projection data are measured by the imaging system; obtaining a system probability matrix that relates each of the projection data to each basis function of the polar or cylindrical image definition; restructuring the system probability matrix into a block circulant matrix and converting the system probability matrix in the Fourier domain; storing the projection data into a measurement data vector; providing an initial polar or cylindrical image estimate; for each iteration; recalculating the polar or cylindrical image estimate according to an iterative solver based on forward and back projection operations with the system probability matrix in the Fourier domain; and converting the polar or cylindrical image estimate into a Cartesian image representation to thereby obtain a reconstructed image.

The invention discloses a circulant matrix transformation based and ciphertext computation supportive encryption method. The method includes the steps: firstly, encrypting original data by means of converting the original data into vectors, then converting the vectors into a circulant matrix and encrypting through a key matrix to obtain an encrypted outsourcing matrix; secondly, encrypting computational parameters by means of converting the computational parameters into vectors, then converting the vectors into a circulant matrix and encrypting through a key matrix to obtain an encrypted computational parameter matrix; thirdly, performing arithmetic operation of an encrypting matrix to obtain an encrypted operation result; fourthly, decrypting the encrypted operation result through the key matrix to obtain a circulant matrix, and then selecting one line / column of the circulant matrix to be added to obtain a plaintext of the operation result. The method is particularly suitable for outsourcing storage and computation of confidential data in a cloud computing environment, and can be used for protecting the confidential data of persons or enterprises; the method is supportive to four-rule hybrid operation of infinite addition, subtraction, multiplication and division of encrypted numerical data.

The invention discloses a cyclic matrix video tracking method with partition. The method comprises a step of dividing a target into a plurality of sub targets with the same size and carrying out cosine window adding preprocessing on each sub target, a step of carrying out cyclic matrix tracking on each sub target respectively to obtain the tracking result of each sub target, and calculating the confidence level of the result, and a step of combining sub target tracking results and confidence levels to obtain the real position of the target. According to the method, the idea of partition is used, the target is subjected to partition processing, each sub target is subjected to cyclic matrix tracking respectively, the spatial distribution information of the target and a background is fully utilized, and the robustness of a video tracking algorithm is raised. According to the method, a complex scene video can be subjected to robust tracking, and the conditions of target scale change, serious blocking, target rapid change, 3D rotation and the like are effectively processed. In addition, the tracking speed is fast, the video processing speed can reach dozens of frames per second, and a real-time requirement is completely satisfied.

In an encoding method to a self-orthogonal QC code whose parity check matrix is expressed by at least one circulant matrix, a code sequence is generated which satisfies a check matrix. The check matrix is designed so that a column weight w of each circulant matrix is three or larger and a minimum hamming distance of the code is w+2 or larger.

The invention discloses an approximation optimization and signal acquisition reconstruction method for a 0-1 sparse cyclic matrix, belongs to the technical field for the design and optimization of measurement matrix in compressive sensing, and provides a posteriori optimizing method which is easy to implement by hardware and can ensure signal reconstruction effect, wherein the 0-1 sparse cyclic matrix is adopted in the measurement stage, and a Gaussian matrix is adopted in the reconstruction stage. The method comprises the following steps: orthonormalizing the row vector and unitizing the column vector of the measurement matrix obtained by the i-1th iteration by the ith iteration; and optimizing the 0-1 sparse cyclic matrix by taking the maximum value of the absolute value of the correlated coefficient between each row and column vector, the convergence stability of each row vector module and the row and column number of each row and column subjected to Gaussian distribution as the criteria. The posteriori optimization of the measured data and measured matrix is completed by solving a transition matrix and an approximate matrix. The method establishes the foundation for the compressive sensing to be practical from the theoretical study.

A regular quasi-cyclic matrix is prepared, a conditional expression for assuring a predetermined minimum loop in a parity check matrix is derived, and a mask matrix for converting a specific cyclic permutation matrix into a zero-matrix based on the conditional expression and a predetermined weight distribution is generated. The specific cyclic permutation matrix is converted into the zero-matrix to generate an irregular masking quasi-cyclic matrix. An irregular parity check matrix in which the masking quasi-cyclic matrix and a matrix in which the cyclic permutation matrices are arranged in a staircase manner are arranged in a predetermined location.

The invention relates to a method for designing a circular array constant beamwidth beam former. The method for designing the circular array constant beamwidth beam former is simple and precise and is provided according to an even circular array. The characteristic of a circulant matrix is utilized in the method, an exact solution to a circular array minimum square error beam pattern synthesis problem is provided, and a finally-composited beam and a minimum square error are simply represented as the sum of subcomponent superposition. When the beam is expected to be transformed into a proper form, a closed expression of a weight vector of the constant beamwidth beam former can be obtained. The method overcomes the defects of the complex and imprecise operation in the prior art, an optimal solution is precisely represented as the sum of subcomponent composited, and the closed expression exists.