61 results about "Harmonic coefficient" patented technology

Formation properties in a vertical section of a wellbore are determined by considering the vertical section as consisting of one or more segments. Measurements are obtained with a directional resistivity tool at two or more measurement stations within each segment for which the complex 0^th harmonic coefficients for the obtained measurements are non-trivially different from one another. For each such segment, the phase shift and attenuation are determined using the complex 0^th harmonic coefficients obtained for that segment and an inversion is performed for the formation properties using the determined phase shift and attenuation for that segment. Formation properties for that segment may be output to a display or memory storage device. For certain segments, one or more gain factors may be obtained. The gain factors are used to correct the measured voltages for certain neighboring segments and the corrected voltages inverted to obtain anisotropy and formation structure.

The invention discloses a method for identifying a motor magnetic pole pair number of a mechanical periodic load. The method comprises the following steps that: a control motor runs at a preset given speed, and a coordinate converter converts a d shaft reference current and a q shaft reference current into a three-phase reference current transmitted to an inverter, wherein the d shaft reference current is zero, and the q shaft reference current is a preset current; then a three-phase working current of a motor is collected with a preset sampling frequency, and the collected three-phase working current is converted into a d shaft working current and a q shaft working current; conversion from a time domain to a frequency domain is carried out on the q shaft working current having preset sampling points, and frequency domain signals are generated; the frequency of a harmonic coefficient having the largest amplitude in the frequency domain signals is obtained; and according to the frequency and the preset given speed, the magnetic pole pair number of the motor is calculated. The invention further discloses a device for identifying the motor magnetic pole pair number of the mechanical periodic load. According to the invention, the motor magnetic pole pair number of the mechanical periodic load is automatically identified, and the universality of a motor control circuit is improved.

The invention discloses a multi-strategy image fusion method under a compressed sensing framework, mainly solving the problems of large calculated amount, high time complexity and large storage space of the traditional image fusion method. The multi-strategy image fusion method comprises the following implementation processes: inputting original images A and B and dividing the original images A and B into local images X1 and X2 of C*C in size; respectively carrying out Fourier transformation on X1 an X2 to obtain coefficient matrixes y1 and y2; observing y1 and y2 respectively by adopting a Fourier coefficient low-frequency full variable-density observing model to obtain observation vectors f1 and f2; calculating harmonic coefficients H1 and H2 and frequency-spectrum matching degree S according to f1 and f2; selecting a threshold T and calculating a weighting coefficient; comparing the weighting coefficient, the threshold and the frequency-spectrum matching degree to calculate a fused observation vector f; and iterating the observation vector f for twenty times by using a Split Bregman reconfiguration algorithm to finally obtain a required fused image. Compared with the traditional fusion method, the multi-strategy image fusion method provided by the invention has the advantages of low calculation complexity and good fusion effect, and can be used for video tracking, target recognition and computer vision.

The invention discloses a multi-harmonic multi-input multi-output feedforward self-adaptive controlling method for helicopter body vibration and belongs to the field of active controlling of helicopter vibration. Aiming at the characteristic of helicopter body vibration under stimulation of the rotor vibration load with multi-stage harmonic frequency and multiple directions and based on the minimum mean square error method and harmonic coefficient identification, the multi-input multi-output feedforward self-adaptive controlling method of helicopter body vibration under the multi-harmonic and multi-load simulation is put forward, so that the purpose of reducing helicopter body vibration is achieved, and when the vibration phase, vibration amplitude and vibration frequency are changed, the good self-adaptive controlling performance is achieved.

The invention discloses a digital background correction method applicable to a pipelined analog-to-digital converter; by adding pseudorandom quantity, the information of sampling capacitance mismatch and harmonic coefficients of an operation amplifier can be obtained to further correct the main output of the pipelined analog-to-digital converter. The method has the advantages of short convergence time and high error estimation precision, and the performance of the analog-to-digital converter is greatly improved.

A method for obtaining fully gain compensated propagation measurements includes rotating an electromagnetic logging while drilling tool in a subterranean wellbore. The tool includes first and second transmitters and first and second receivers axially spaced apart from one another in which each of the transmitters and each of the receivers include an axial antenna and collocated first and second transverse antennas. The first and second transverse antennas in the first receiver are rotationally offset by a predefined angle from the first and second transverse antennas in the first transmitter. A plurality of electromagnetic voltage measurements are acquired at the first and second receivers while rotating and processed to compute harmonic coefficients. The harmonic coefficients are mathematically rotated through at least the predefined angle to obtain rotated coefficients. Ratios of selected ones of the rotated coefficients are processed to compute fully gain compensated measurement quantities.

The invention belongs to the ground nuclear magnetic resonance data processing field and discloses a method for eliminating an adjacent-frequency harmonic in ground nuclear magnetic resonance data. The method comprises the following steps of inputting ground nuclear magnetic resonance measurement data, measuring an experimental-location ground magnetic field and calculating a Larmor frequency; searching a power frequency harmonic fundamental frequency, modeling a power frequency harmonic and calculating and acquiring all harmonic coefficients; and determining whether there is an adjacent frequency harmonic according to a frequency difference between a Larmor frequency and each harmonic frequency, if there is no adjacent frequency harmonic, using the harmonic fundamental frequency and the harmonic coefficients to calculate and acquire a harmonic model, and subtracting the harmonic model from measured data, and if there is the adjacent frequency harmonic, removing the power frequency harmonic outside an adjacent domain harmonic and then removing the adjacent domain harmonic based on a fitting method. In the invention, under the condition that a nuclear magnetic resonance signal is not lost, the influence of the adjacent-frequency harmonic in the power frequency harmonic on subsequent data processing and inversion is removed. Especially when the Larmor frequency of the experimental location is close to the high order harmonic of the power frequency harmonic, a ground nuclear magnetic resonance signal characteristic can be accurately extracted and inversion result accuracy is increased.

A lapping plate topography system includes a measuring apparatus for measuring the surface of a lapping plate, and an analysis apparatus for analyzing and presenting the data resulting from such measurements. The measurement apparatus has a non-contacting capacitive probe for measuring a height of the surface of the lapping plate, a rotary arm assembly for moving the probe in an arc over the surface of the lapping plate, and a spindle assembly for rotating the lapping plate about its center. The computer-based analysis apparatus is operable to input from the measurement apparatus the measured height at a plurality of data points on the surface of the lapping plate, calculate Fourier transform harmonic coefficients based on the plurality of measured heights, calculate surface ripple coefficients based on the calculated Fourier transform harmonic coefficients, and output the calculated surface ripple coefficients to an appropriate display device.

The invention discloses a method for eliminating a harmonic wave of a radio frequency circuit and a radio frequency circuit. The radio frequency circuit is of a structure that in a transmission branchcircuit, a baseband signal generated by a baseband signal generation module is input into a frequency mixer after being subjected to frequency conversion on a first frequency converter, after the baseband signal passes through an inverse harmonic signal module, an inverse harmonic signal is generated, the inverse harmonic signal is input into the frequency mixer after being subjected to frequencyconversion on a second frequency conversion module, the frequency mixer outputs a mixed signal after carrying out frequency mixing on the baseband signal subjected to frequency conversion and the inverse harmonic signal subjected to frequency conversion, and after the mixed signal passes through a digital-to-analog converter and a radio frequency power amplifier, a radio frequency signal is output; in a feedback branch circuit, the radio frequency signal output by the radio frequency power amplifier is subjected to down-conversion by a third frequency conversion module after being attenuatedby a radio frequency attenuator and converted by an analog-to-digital converter, and a feedback signal is output to the inverse harmonic signal module; and the inverse harmonic signal module calculates an inverse harmonic coefficient on the basis of a currently generated harmonic signal, the received baseband signal and the feedback signal, and generates an inverse harmonic signal on the basis ofthe inverse harmonic coefficient.

A LED dimming device, and a LED dimming and a driving circuit using such LED dimming device are discussed. In present embodiment, the LED dimming device multiplexes an inputting switch and/or a sampling module of the LED driving circuit for dimming. such LED dimming device will not affect the sine waves of input current, in such a way, power factor and work efficiency will be increased while the harmonic coefficient and interference signal will be reduced.

The invention discloses a harmonic source identification method and device, terminal equipment and a storage medium. The method comprises the steps of acquiring bus voltage data in a power system andcurrent data of each feeder; performing phase-shift processing on the bus voltage data and the current data of each feeder by a mobile current data window; and performing Fourier transform on the processed bus voltage data and the processed current data of each feeder to obtain a data set; calculating a correlation coefficient and an integral harmonic coefficient of each feeder according to the data set; calculating load linearity of each feeder according to the correlation coefficient and the integral harmonic coefficient of each feeder; and judging a feeder where a main harmonic source is located according to the load linearity of each feeder so as to achieve identification of the harmonic source. By the method, the main harmonic source in the power system can be accurately identified, and the harmonic identification sensitivity is improved.

The invention relates to a method for measuring the linearity of a gradient magnetic field generated by gradient coils in an MRI (magnetic resonance imaging) system, which is characterized by comprising the steps 1, setting sampling points in an imaging area; 2, acquiring a z-direction magnetic field value generated by the gradient coils at each sampling point; 3, calculating harmonic coefficients A<n, m> and B<n, m> of a z-direction magnetic field according to the z-direction magnetic field value of the sampling point; and 4, calculating the volume root mean square linearity Vrms of the gradient magnetic field according to an integral formula. According to the invention, the volume root square mean linearity Lvrms of the gradient magnetic field is calculated by adopting harmonic coefficient expansion, and three-dimensional volume integrals can be expanded into an expression of the sum of squares of the harmonic coefficients as for a spherical imaging area, thereby having very high efficiency and precision.

The invention discloses a motor fault detection system based on the total harmonic coefficient of current, and the system comprises a current collection module, a DSP processor, and a fault display and protection module. The current collection module transmits a collected current of a motor stator to the DSP processor, and the DSP processor is connected with a fault current harmonic comparison library and a fault display and protection module. The fault current harmonic comparison library carries out the pre-calibration of the corresponding relation between a fault state and the total harmoniccoefficient of current. The DSP processor calculates and obtains the total harmonic coefficient of current according to the collected current, and obtains the fault information through the fault current harmonic comparison library. The DSP processor transmits a control signal to the fault display and protection module, and the fault display and protection module is used for displaying fault information and transmitting a motor protection signal. The system is advantageous in that the system can quickly obtain the fault information and type through the pre-calibrated fault current harmonic comparison library, timely cuts off a drive circuit, and protects the safety operation of a motor.

The invention relates to a provincial and municipal access data center optimization method for a power customer service center to predict the number of potential users based on a logistic model. The specific technical scheme is as follows of according to existing access user samples and common user samples, collecting and judging the elements influencing the access of a user to a data center; according to the influence factors in the step 1, adopting a logistic regression method to train samples to obtain a regression model used for calculating the potential user probability of each province and city; estimating the potential user number of each province and city according to the access probability in the step 2; and establishing an optimization model of the provincial and municipal user access data center and obtaining an optimization scheme of the provincial and municipal user access data center. According to the present invention, the number of potential users of each province and city is estimated through the logistic logistic regression model, the maximum load capacity and the resource utilization rate of each data center are considered, and the province and city access data center problem is converted into an optimization model which considers the load balance and the time delay in a tradeoff mode by adjusting the size of a harmonic coefficient.

The invention discloses an anti-islanding control algorithm and system employing an active frequency drift with voltage frequency absolute value positive feedback. The method comprises the following steps: (S1) detecting a common coupling point voltage frequency f and an amplitude I of common coupling point current and calculating inverter output current i(<omega>t); (S2) judging whether the condition that the common coupling point voltage frequency f is less than the maximal frequency f<max> or greater than the minimal frequency f<min> is established or not, if so, executing the step (S5), if not, executing the step (S3); (S3) adding disturbance to grid-connected output current of an inverter by the inverter output current i(<omega>t) calculated in the step (S1) in each cycle, and detecting the common coupling point voltage frequency f' after the disturbance is added; (S4) judging whether the f' is greater than the maximal frequency f<max> or not, if so, entering the step (S5), or else, returning to the step (S1); and (S5) adopting an anti-islanding action. According to the method, the problems of relatively large non-detection zone and total harmonic coefficient (THD) of an active frequency drift method (AFD) are overcome; and the islanding phenomenon can be quickly detected.