31 results about "Underdetermined system" patented technology

Real-time packet-based audio communications over packet-based networks frequently results in the loss of one or more packets during any given communication session. The real-time nature of such communications precludes retransmission of lost packets due to the unacceptable delays that would result. Consequently, packet loss concealment methods are employed to “hide” lost packets from the listener. Unfortunately, conventional loss concealment methods, such as packet repetition or stretch/overlap methods, do not fully exploit information available from partially received samples. Therefore, when a single frame of N coefficients is lost, 2N samples are only partially reconstructed, thereby degrading the reconstructed signal. To address this problem, an optimized packet loss concealment solution is identified for particular lost packets by solving an underdetermined system of linear equations representing partially received samples while minimizing a computed error based on a model of the signal obtained from neighboring blocks or frames received by the decoder.

Disclosed is a high-resolution image reconstruction method using a focal underdetermined system solver (FOCUSS) algorithm. The method comprises the steps of: outputting data for an image of an object; downsampling the outputted data; transforming the downsampled data into low-resolution image frequency data; and reconstructing a high-resolution image from the transformed low-resolution image frequency data by applying focal underdetermined system solver (FOCUSS) algorithm.

The invention discloses an array sparse method for a broadband non-frequency-variable multi-beam imaging sonar. With the Bessel function, fitting of influences on array guiding vectors by different frequency points in the broadband signal bandwidth is performed and a broadband signal multi-beam forming model under the far-field situation is established; on the premise that the formed multiple beams approximate a reference beam, a minimum number of effective array elements are searched and multiple sets of weighting coefficients are calculated; a highly nonlinear sparse array optimization problem is transformed into a sparse signal reconstruction problem in the compressed sensing theory, a reconstruction weighting coefficient is calculated iteratively by an underdetermined system localizedsolution algorithm, and a sparse array structure is determined; a convex optimization theory is introduced so as to form a plurality of low-side-lobe beams and a multi-beam array sparse side-lobe suppression model for array element excitation is established. According to the invention, the main lobes of a plurality of formed beams are not extended with changes of signal operating frequencies; andpeak side-lobe levels of multiple beams formed by the sparse array are reduced effectively.

The invention belongs to the technical field of remotely sensed image processing, and provides a snow passive microwave mixed pixel decomposition method based on the classified information of five types of ground features. According to five types of typical underlying surfaces affecting the radiation characteristic of snow, the method acquires the classified data of the ground features with high special resolution in an observed region, utilizes the different characteristics of the microwave radiation of snow on the different underlying surfaces and selects a microwave antenna gain function and a sampling rate to build a snow passive microwave mixed pixel decomposition model, and adopts the least square method with constraint conditions to iteratively solve an underdetermined system of equations, thus realizing snow passive microwave mixed pixel decomposition. The method can effectively solve the problem of the mixed pixels of passive microwaves of snow, improves the precision of snowparameter inversion, and has a significant application value in fields such as climate and hydrological research and snow disaster assessment.

A genome-scale metabolic network reconstruction for Clostridium acetobutylicum (ATCC 824) was created using a new semi-automated reverse engineering algorithm. This invention includes algorithms and software that can reconstruct genome-scale metabolic networks for cell-types available through the Kyoto Encyclopedia of Genes and Genomes. This method can also be used to complete partial metabolic networks and cell signaling networks where adequate starting information base is available. The software may use a semi-automated approach which uses a priori knowledge of the cell-type from the user. Upon completion, the program output is a genome-scale stoichiometric matrix capable of cell growth in silico. The invention also includes methods for developing flux constraints and reducing the number of possible solutions to an under-determined system by applying specific proton flux states and identifying numerically-determined sub-systems. Although the model-building and analysis tools described in this invention were initially applied to C. acetobutylicum, the novel algorithms and software can be applied universally.

The invention provides a data processing method and system suitable for a wireless distributed perception system. The data processing method includes the following steps that sensor nodes collect perception data with relevance; intermediate nodes process the perception data by utilizing random linear network codes; the number of the sensor nodes is N, the number of aggregation nodes is m, source data are supposed to be x, data received by the aggregation nodes are y, the aggregation nodes combine received input vectors to acquire a system of linear equations, and due to the fact that m (N and the system of linear equations) is underdetermined, the problem of solving the underdetermined system of equations is converted to the problem of minimizing l1, and original perception data are reconstructed; a receiving terminal receives the original perception data. The data processing method and system suitable for the wireless distributed perception system have the advantages that due to the fact that the compressed perception theory is introduced to the decoding stage of the aggregation nodes, the problem of 'all or nothing' is effectively solved.

The invention provides a method and a system for finding a direction of a target source of an array signal. The method comprises the following steps: performing signal sampling on the array signal to be detected to obtain a sampling matrix of the array signal, and acquiring a preset base matrix and a regularization parameter; performing singular value decomposition on the sampling matrix to obtain observation data, transferring the observation data into a signal subspace to obtain a target matrix; determining a target source direction of the array signal according to the target matrix, the base matrix, the regularization parameter and a preset direction finding equation set. According to the scheme, the target source direction finding of a high-dimensional signal can be abstracted into solution of underdetermined system of equations, so that effects of lower reconstruction error and higher success rate can be achieved within a larger signal-to-noise ratio range, and signals with higher correlation can be identified.

The invention discloses a multichannel reconstruction method for periodical non-uniform sampling SAR (synthetic aperture radar) signals. The method includes: periodically changing pulse repetition frequency of a radar transmitter to acquire a periodical non-uniform sampling SAR echo signal, constructing a constraint underdetermined system of linear equations of a reconstruction filter according to channel features of the periodical non-uniform sampling SAR echo signal to acquire signal power after multichannel reconstruction, combining the underdetermined system of linear equations and minimum conditions of the signal power to acquire the optimal reconstruction filter, and using the optimal reconstruction filter to complete multichannel reconstruction.

The invention relates to the technical field of camera calibration and in particular discloses a single image camera calibration method based on compressed sensing. The method is just required to photograph a calibration plate once, and solves the optimal solution of a single image by using a compressed sensing reconstruction algorithm by setting qualification conditions for six unknown quantitiesin a underdetermined system of equations of the single image via a Zhang's planar calibration method, thereby greatly simplifying the process of solving the internal matrix and the foreign matrix ofthe single image. The used compressed sensing reconstruction algorithm is subjected to self loop optimization and high camera calibration quality and high calibration efficiency are achieved.

The invention relates to an underdetermined system real orthogonal space-time block code blind identification method based on robust competitive clustering, and belongs to the technical field of signal processing. The method comprises the steps of modeling a signal receiving model relevant to a virtual channel matrix, wherein the virtual channel matrix comprises space-time code information and can be used for identifying the space-time code; then carrying out blind estimation on the virtual channel matrix by using a robust competitive clustering algorithm; extracting the sparseness of the relevant matrix of the virtual channel matrix and an identification characteristic parameter of an energy ratio of non-main diagonal element energy to main diagonal element energy; and finally performing orthogonal space-time block code identification according to the parameter. By the adoption of the algorithm, a real orthogonal space-time block code signal is subjected to effective blind identification under low complexity, and the real orthogonal space-time block code signal can well work under a condition of a low input signal-to-noise ratio, so that the system performance is improved; moreover, the robust competitive clustering algorithm can be also used for carrying out blind estimation on the number of source signals, and the underdetermined system real orthogonal space-time block code blind identification method has a wide application prospect.

A variable to be determined is expressed as a product of a state variable and a structural variable for each element. The structural variable is a monotonically increasing function of a control variable that takes a real number value, and is thus limited to a real number of 0 to 1. An objective function defined as a function of the state variable and structural variable or the state variable and control variable is used. In each iteration, a computer executes: a state variable updating step of updating a value of each element of the state variable on the basis of information of the objective function with respect to the state variable; and a structural variable updating step of updating a value of each element of the structural variable on the basis of information of the objective function with respect to said structural variable.

A method and apparatus for a streamlined electronic credit transaction that provides more security in a streamlined transaction process than any current deferred net settlement system. The removal of the physical credit card restores the proper risk balance to all participants and performs processing in real time, faster than any current system. The method relies on secure authentication and encryption security communications, based on the provably secure unbreakable mathematics of underdetermined systems of equations, which are maintained everywhere throughout the transaction process.