37 results about "Iteration function" patented technology

The invention provides a key expanding method for a block cipher algorithm, which is used for generating each round of subkeys in the block cipher algorithm. The method provided by the invention mainly comprises the following step of calculating an iteration function for generating a subkey, wherein the iteration function is formed by a nonlinear operation, a constant operation and a cycle shift operation. The method provided by the invention can effectively and conveniently generate the subkeys, effectively reduce storage space, has higher realizing speed compared with a common commercial block cipher algorithm, can meet the requirements on real-time encryption and decryption, and simultaneously has higher safety.

The invention provides a method for predicting the shaking of an impeller. The method includes the steps of conducting grid division on an entity model of the impeller through a finite element analysis method, dividing the machining process of the impeller into a plurality of machining sub-stages, obtaining modulus parameters of all the machining sub-stages of the impeller through the finite element analysis method, establishing a transfer function of each machining sub-stage of the impeller, obtaining the modulus parameters of a tool system and the modulus parameters of an impeller system through an experiment modulus analysis method, establishing a transfer function of a tool-impeller system, calculating the difference between the modulus parameters of each machining sub-stage of the impeller and the modulus parameters, obtained through the experiment modulus analysis method, of the impeller system, obtaining the modulus parameter deviation vector, conducting iteration on the modulus parameter deviation vector through a modulus parameter iteration function, obtaining the final modulus parameters of the modulus parameter deviation vector within the modulus parameter tolerance range of all the machining sub-stages, and drawing the milling stability lobe graph of all the machining sub-stages of the impeller.

The invention discloses a control parameter optimization method for improving the phase commutating failure restraining capacity of a direct current system. The method comprises the following steps that after initialization, through an interface technology between PSCAD and MATLAB, a first interface module and a second interface module are established, the first interface module is used for calling an optimization algorithm, a whole iteration function of the algorithm is carried out, when each-time simulation is started, through an improved particle swarm algorithm, particle positions are updated, and controller parameters are returned to the PSCAD; and the second interface module is used for receiving the particle positions returned by the PSCAD and optimizing target functions after each-time simulation is over, and the global optimum particle positions and the individual optimum positions are updated. Through the interface technology between the PSCAD and the MATLAB, combining calling of the PSCAD and the MATLAB is achieved, the improved particle swarm algorithm is used for searching for the optimum control parameters, a multi-time operation function in the PSCAD is used, calling of multi-time software can be achieved, and accordingly optimization searching of control parameters is achieved.

The invention discloses a parallel-beam CT sparse angle reconstruction method based on non-standard fast Fourier transformation and alternating direction method, which overcomes the problem that the image reconstruction method still has defects in the prior art. The steps of the invention are as follows: perform one-dimensional FFT transformation on the projection data collected by parallel beam CT to obtain the corresponding projection frequency domain data in polar coordinates; based on the projection frequency domain based on polar coordinates, use NUFFT technology to realize image space Frequency domain transformation to avoid the loss of precision caused by frequency domain interpolation, and establish a TV minimization image reconstruction model; in the process of restoring the image to be reconstructed from the projected frequency domain, a frequency domain optimization model based on TV minimization is designed, using alternate The direction method is used to iteratively solve the TV minimization model through the augmented Lagrangian function method and the alternating direction multiplier method. The invention combines the NUFFT technology and the advanced alternating direction idea in the optimization strategy, can avoid interpolation in the frequency domain, requires less computing and storage resources, and has good convergence performance.

The invention discloses an object and fractal-based multi-ocular three-dimensional video compressing and decompressing method. In multi-ocular three-dimensional video encoding, a middle ocular video is selected as a reference ocular video and is compressed by using a motion compensation prediction (MCP) principle; and other ocular videos are compressed by using a disparity compensation prediction(DCP)+MCP-based principle. Taking a trinocular video as an example, the middle ocular video is selected as the reference ocular video and is encoded by using a single MCP mode principle, wherein the method comprises the following steps of: first, acquiring a video object segmentation plane, namely an Alpha plane, by a video segmentation method, encoding a start frame by adopting discrete cosine transform (DCT), and performing block motion estimation / compensation encoding on a non-I frame; then, judging the area attribute of an image block by utilizing the Alpha plane, if the block is not in acurrently encoded video object area, then not processing the external block, and if all of the block is in the currently encoded video object area, searching a most similar matching block in a reference frame of a previous frame, namely the middle ocular video, by a full search method; and finally, compressing coefficients of an iteration function system by utilizing a Huffman encoding method, ifpart pixels of the block are in the currently encoded video object area while part pixels are not in the currently encoded video object area, independently processing a boundary block. A left ocular video and a right ocular video are respectively encoded by adopting the MCP+DCP mode; and when the DCP encoding mode is performed, the polarization and the direction in a three-dimensional parallel camera structure are fully utilized.