406 results about "Fourier analysis" patented technology

A radar system for transmitting a FMCW radar sensor signal encompassing a series of frequency modulation ramps and phase-modulated with a first code sequence orthogonal to a respective other code sequence with which a time-synchronized transmitted signal of another FMCW radar sensor is phase-modulated; the radar echoes are phase-demodulated with a code sequence correlating with the first code sequence; and a distance and/or a relative speed of a localized object is identified from a Fourier analysis frequency spectrum, in a first dimension over sampled radar echo values of a frequency modulation ramp, and in a second dimension over the phase-demodulated sequence of radar echoes of the ramps of the transmitted signal; and a vehicle fleet radar system having an FMCW radar sensor in which a code set satisfying a code set orthogonality condition with a code set of a radar sensor of another vehicle is used for phase modulation/demodulation.

Rapid spectrum assay of multiple samples with infrared light is made possible by devices and methods that increase total light throughput. Multiple wavelength scan with Fourier analysis is combined with large numbers of sample wells located within infrared light compatible solid materials. In particular, very large scale measurement devices and systems for their use are fabricated from lithography and other techniques used for semiconductor processing.

A methodology for automatic a priori data pattern analysis is provided. Described methods allow consistent and objective determination of outliers; trend; seasonality; and level shifts; and the production of better models and more accurate forecasts. In addition, a two-step way to automatically determine seasonality and locate possible events in the data set is described. Decomposition of data into seasonal, trend and level components; detection of outliers and level-shift events in the time series based on statistical analysis of the time series; detection of seasonality based on statistical analysis of clusters of data, known as cluster-based seasonality analysis, or CBSA; evaluation of the goodness of fit of a model to data, using the existing goodness of fit indicator, R²; and seasonality analysis, using a sequence of cluster-based seasonality analysis (CBSA) and Fourier analysis are described.

An output of a photovoltaic (PV) device is predicted by applying Fourier analysis to historical data to obtain frequencies and a mean of the frequencies in the data. Regression analysis is applied to the data to obtain a regression coefficient. Then, the prediction is a sum of the mean at the time step and a deviation from the mean at a previous time step, wherein the means are represented and approximated by selected frequencies, and the deviation for the previous time step is weighted by the regression coefficient.

The invention discloses a spectral measurement method based on optical frequency combs. The measurement method is characterized in that firstly, an annular laser resonant cavity based on a phase modulator is actively modulated by use of a first optical frequency comb controllable in time domain and frequency domain so that the annular laser resonant cavity is converted into a second optical frequency comb having tiny difference in repetition frequency with the first optical frequency comb, and spectrum detection is performed on the two optical frequency combs to obtain an interference signal carrying the information of a sample to be tested, and meanwhile, frequency beating is performed on the two optical frequency combs and continuous frequency stabilized laser, respectively, the difference frequency signal of two obtained beat frequency signals is mixed with the interference signal, and a signal obtained by virtue of detection mixing is taken as a spectral signal for Fourier analysis so as to reduce the optical information of the sample to be tested. The spectral measurement method has the advantages that the error of the spectral detection due to own phase drift of a dual-optical comb system can be eliminated, and therefore, the resolution and the detection accuracy of the spectral measurement can be improved.

A position sensor encodes absolute position via n consecutive members of a pseudorandom sequence of bits, where each bit (30a-30k) comprises a region of high transmission or reflectivity adjacent to a region of low transmission or reflectivity. The pseudorandom sequence is chosen such that every series of n consecutive bits (30a-30k) in the sequence is predominantly formed from a predetermined bit value (1 or 0). The light transmitted or reflected from the series is therefore detected as a substantially periodic intensity pattern (42), which can be processed via Fourier analysis to yield an accurate interpolation of relative position. An example is given of a pseudorandom sequence, which can be represented as a cyclic Manchester code, in which at least 8 members of every series of 11 consecutive bits has a bit value of 1.

A method and apparatus for treating a sample for acquiring high-definition magnetic resonance images (MRI images) or high resolution nuclear magnetic resonance (NMR) spectra even in the presence of magnetic field distortions within one or multiple scans. The spatial nature and temporal dependence of the field inhomogeneities are determined a priori using any of several literature procedures. A static or oscillating magnetic field gradient is applied on the sample so as to endow spins at different positions within the sample with different resonance frequencies. A phase- and amplitude-modulated radiofrequency (RF) pulse is applied in unison with the magnetic field gradient so as to endow spins at different positions within the sample with a homogeneous excitation/inversion profile. The nature of the spatially-selective RF irradiation is tailored in such a way that, when added on top of the effects of the inhomogeneities, the spins' evolution phases and their signal amplitudes at the time of the acquisition become independent of the inhomogeneities. The spin signals thus created are captured and decoded, so as to obtain the spins' response as if the inhomogeneity was not present. The collected data is processed to a suitable rearrangement and Fourier analysis procedure to retrieve a final undistorted image or spectrum. The magnetic field gradient can be oscillated to impose this kind of inhomogeneity corrections on multiple spatial dimensions sequentially, or simultaneously.

The invention is a automatic identification method and system based on the power quality disturbances of the information fusion, characterized by: collecting the transient and steady-state measurement datum associated with the power quality disturbances from the Power Quality Monitoring System and other automation systems, disposing of noise such as pretreatments; Using the method combining Fourier analysis, small wave multi-resolution decomposition and analysis of the correlation functions, distilling the from the disturbance datum, establishing the disturbance eigenvector, and as a the input characteristic vector of three probabilistic neural networks, realizing the mapping from a feature space to the disturbance space; the output of three probabilistic neural networks regarded as the evidence body of independent of each other, realizing Information Fusion by the use of D-S evidence theory, obtaining recognition results. This invention through the correct selection and extraction of disturbance eigenvectors, can input neural network parallel in classification and reflect the disturbance situation from the various aspects, thus effectively enhancing the correct identification rate of disturbance, a first step in Intelligent Recognition of the power quality disturbances.

A computer-based stroboscopic interferometric microscope system for measuring the topography of a microscopic vibratory object includes an interferometric microscope equipped with a multiple-color (e.g., LED) or white-light source, a mechanical scanning apparatus for varying the optical path difference between the vibratory object and a reference surface, a camera having a two-dimensional detector array, and digital signal processing apparatus for determining surface height from interference data. Interferograms for each of the detector image points in the field of view are generated simultaneously by scanning the object in a direction approximately perpendicular to the object surface illuminated stroboscopically while recording detector data in digital memory. Recorded interferograms for each image point are then transformed into the spatial frequency domain by Fourier analysis, and the surface height for each corresponding object surface point is obtained by examination of the complex phase as a function of spatial frequency. A complete three-dimensional image of the object surface is then constructed from the height data and corresponding image plane coordinates. The three-dimensional image may be presented on a display or hard copy or written to a storage medium.

The invention discloses a control method of a maximum torque per ampere vector control system for a position sensor-free internal permanent magnet synchronous motor, and belongs to the field of motor control. The problems of complexity of a computing method and low accuracy of an obtained current set value in the conventional maximum torque per ampere control strategy are solved. The control system comprises a permanent magnet synchronous motor, an inverter, a space vector pulse width modulation unit, a three-phase-two-phase coordinate conversion unit, a static-rotational coordinate conversion unit, a Fourier analysis unit, a vector angle regulation unit, a rotating speed regulator, a maximum torque per ampere control unit, a first current regulator, a second current regulator, a rotational-static coordinate conversion unit and a rotor position and rotating speed observer. According to the control method, the magnitude of current amplitude is automatically regulated and compared on the basis of a current vector angle gamma, and an operating point with maximum torque per ampere is automatically searched. The system and the method are applied to maximum torque per ampere vector control over the motor.

The invention discloses a method, device and system for suppressing shaking of an electric automobile. The method, device and system are used for suppressing the shaking of the electric automobile andimproving the driving comfort level. The method includes the steps that a rotation speed signal of a motor is obtained; Fourier analysis is conducted on the rotation speed signal, and the frequency and the amplitude of an effective component, causing rotation speed shaking, in the rotation speed signal are obtained, wherein rotation speed shaking is shaking caused by the non-linear relationship between traction torque and the resistance moment of the electric automobile; according to the frequency and the amplitude of the effective component causing rotation speed shaking, a parameter for suppressing rotation speed shaking is obtained; according to the parameter for suppressing rotation speed shaking and the rotation speed signal, compensation torque is obtained through a differential inertial element and a band-pass filtering element; and the compensation torque and given torque are superposed so as to suppress the rotation speed shaking. Due to the fact that the shaking of the electric automobile is suppressed, mechanical resonance generated in the shaking process is reduced, and therefore hardware wear of the electric automobile is reduced.

Systems and methods are described for recording multiple spatially-heterodyned direct to digital holograms in one digital image. A method includes digitally recording, at a first reference beam-object beam angle, a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram to sit on top of a first spatial-heterodyne carrier frequency defined by the first reference beam-object beam angle; digitally recording, at a second reference beam-object beam angle, a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram to sit on top of a second spatial-heterodyne carrier frequency defined by the second reference beam-object beam angle; applying a first digital filter to cut off signals around the first original origin and define a first result; performing a first inverse Fourier transform on the first result; applying a second digital filter to cut off signals around the second original origin and define a second result; and performing a second inverse Fourier transform on the second result, wherein the first reference beam-object beam angle is not equal to the second reference beam-object beam angle and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

A third harmonic distortion corrector is equipped for correcting a third harmonic distortion contained in a two-phase sinusoidal signals with different phases output from an encoder. A third harmonic calculator/detector calculates the amplitude a₃ and the phase φ₃ of the third harmonic using Fourier analysis, based on change in radius r of the Lissajous waveform output from a r-θ converter. The third harmonic distortion corrector corrects the third harmonic distortion of the two-phase sinusoidal signal A4, B4 based on the amplitude a₃ and the phase φ₃ of the third harmonic calculated.

The invention relates to an impulse vibrating method for testing the bridge substructure natural frequency of vibration which uses avoirdupois weight to stroke the pier and tests the vibrating response of the pier to analyze and compute the natural frequency of vibration. It uses avoirdupois weight to stroke the pier top part and tests the speed and hastens response of the bridge. It usually dose multi-stroke and uses the recording wave mode superposition to dispel the noise to obtain the accurate response wave mode. It reads the response wave mode to do Fourier analysis to ascertain Fourier frequency spectrum and combines with the peak spectrum to ascertain the natural frequency of vibration of bridge.

An interference spectroscopy instrument provides simultaneous measurement of specular scattering over multiple wavelengths and angles. The spectroscopy instrument includes an interference microscope illuminated by Koehler illumination and a video camera located to image the back focal plane of the microscope's objective lens while the path-length difference is varied between the reference and object paths. Multichannel Fourier analysis transforms the resultant intensity information into specular reflectivity data as a function of wavelength. This multitude of measured data provides a more sensitive scatterometry tool having superior performance in the measurement of small patterns on semiconductor devices and in measuring overlay on such devices.

Thermoacoustic sensors, such as dynamic pressure sensors, in the combustor measure vibratory responses of the combustor. An integrated monitoring and control system controller correlates sensor readings with combustion thermoacoustic properties in order to identify combustion anomalies by wavelet or Fourier analysis techniques; determine bulk temperature characteristics within the combustor with dominant mode frequency analysis techniques; and optionally determines absolute active path temperatures within the combustor with acoustic pyrometry transmission and time-of-flight analysis techniques. In some embodiments all of the monitoring functions are performed with a commonly shared array of thermoacoustic sensors that function as both combustion dynamics thermoacoustic vibration/wave receivers and acoustic transmitters. The monitored combustion properties are used for controlling gas turbine combustion.