35 results about "Partial fourier" patented technology

In a method and an apparatus for magnetic resonance guided high intensity focused ultrasound (HIFU), precise localization of the focal point of the HIFU is determined by imaging an examination subject in parallel with GRE sequences that respectively include a positive monopolar gradient pulse and a negative monopolar gradient pulse, that respectively encode the acoustic radiation force (ARF)-induced phase shift that is induced by the simultaneous activation of HIFU during the sequences. A GRE phase image is reconstructed from each acquisition sequence, and a difference image is formed between the two GRE phase images, from which the HIFU focal point is determined. An average image is formed of the two GRE phase images from which PRFS temperature map is determined simultaneously to ARFI map. The use of parallel imaging and the use of partial Fourier reconstruction for reconstructing the GRE phase images allows the data to be acquired sufficiently rapidly so as to minimize the adverse effect of tissue heating that occurs with conventional longer-duration, and repetitious, techniques.

In an imaging method and device for water / fat separation in MRI using a two-point Dixon FSE sequence, each refocusing RF pulse corresponds to two readout gradients of the same polarity, each being center-divided into a smaller rear part and a larger front part, and one rephasing gradient of opposite polarity. In running the FSE sequence, each echo signal acquired is subjected to an FFT, to reconstruct an image with water and fat in phase and an image with water and fat in opposed phases. Data of each echo signal are subjected to a partial Fourier transform; and the in-phase water / fat image and the opposite-phase water / fat image are subjected to a water / fat separation algorithm, to obtain a pure water image and a pure fat image.

The invention discloses a spectral analysis calculation method and calculator for illumination intensity data. The calculation method is characterized by including the steps that a sparse format arrangement is performed on the collected illumination intensity data to form data which are distributed in a periodically sparse mode; the illumination intensity data which are distributed in the periodically sparse mode are normalized to be in a power (2, n) form; partial Fourier transformation is performed on the normalized illumination intensity data; fast Fourier transformation is used for calculating the data which partial Fourier transformation is performed on, so that the spectrum of illumination intensity is obtained. The invention further discloses the spectral analysis calculator for the illumination intensity data. According to the technical scheme, on the premise that the distribution characteristics of the data spectrum are not changed, an existing Fourier transformation technology is improved, the periodically sparse characteristic of the illumination intensity is sufficiently utilized, redundancy calculation on zero elements is avoided, and a novel partial Fourier transformation technology is formed. In this way, the efficiency of spectrum calculation is improved.

This application relates to a lidar-based airport wind field feature detection method, device, and equipment. The method includes the steps of: configuring a scanning strategy for a lidar deployed at a predetermined location in the airport according to a set configuration strategy; The Doppler radial velocity information is inverted to obtain the three-dimensional wind field in the scanning volume; the wind field data below 600 meters is extracted from the three-dimensional wind field, and the corresponding F factor value is calculated according to the wind field data below 600 meters; The radial wind speed data of 35.3° altitude angle in the Doppler radial velocity information is calculated by the partial Fourier decomposition algorithm to obtain the kinetic energy intensity of the turbulent flow at different heights; the multiplicity of each altitude angle in the Doppler radial velocity information is extracted The Doppler spectrum data is used to calculate the turbulent dissipation rate at each radial distance of the wind field through the Doppler spectrum method. The above scheme achieves the effect of strong wind field comprehensive detection performance.

The invention discloses a Doppler extension processing method for underwater acoustic high-speed OFDM communication. The method is composed of the following three modules, including a Doppler estimation and compensation module, a channel estimation module based on compressed sensing and a part of fast Fourier Transform demodulation module, the core of which is a partial fast Fourier transform demodulation module, and the output of the other two modules is used as the input of partial fast Fourier transform. The present invention improves the traditional OFDM demodulation method, adopts partial Fourier transform as a demodulation method for the first time, and can eliminate part of the Doppler spread in the demodulation process; by processing the Doppler spread twice, it can The influence of Doppler extension on the signal is reduced to a relatively low range, especially for fast-changing underwater acoustic channels, so it has higher processing performance for Doppler extension.

The invention discloses a microscopic imaging method based on a partial Fourier space, comprising the following steps: S1, collecting microscopic images of a sample under multi-angle lighting; and S2, getting a whole high-resolution image through an iteration process of a PFPM method. Step S1 includes collecting a central image of the sample and multiple images obtained under lighting of a half light matrix in a set range. Step S2 includes the sub steps of processing the central image to get an iterative initial figure of Fourier space, iteratively updating the multiple images one by one according to the iterative initial figure to complete a round of iteration, performing a plurality of rounds of iteration to get the Fourier space of the high-resolution image, and filling in the missing data according to the Fourier space of the high-resolution image and based on the conjugate symmetry of Fourier transform to generate a whole high-resolution image. Through the microscopic imaging method based on a partial Fourier space, the iteration speed is increased. The application scope of the microscopic imaging method based on a partial Fourier space is expanded.