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102 results about "Rank correlation" patented technology

In statistics, a rank correlation is any of several statistics that measure an ordinal association—the relationship between rankings of different ordinal variables or different rankings of the same variable, where a "ranking" is the assignment of the ordering labels "first", "second", "third", etc. to different observations of a particular variable. A rank correlation coefficient measures the degree of similarity between two rankings, and can be used to assess the significance of the relation between them. For example, two common nonparametric methods of significance that use rank correlation are the Mann–Whitney U test and the Wilcoxon signed-rank test.

Spindle thermal distortion compensation method for precision horizontal machining center

A spindle thermal distortion compensation method for a precision horizontal machining center comprises the steps as follows: a spindle model of a machine tool is simplified structurally; an ANSYS (finite element analysis software)-Workbench is utilized to perform mesh generation on a spindle entity model that is simplified, so as to obtain a spindle finite element model; and boundary conditions are calculated by combining with the practical spindle rotational speed, the environmental temperature, the coolant velocity, the flow rate, the inlet and outlet oil temperature and the like, and configuration is performed. Thermodynamics analysis and statics analysis are carried out in the ANSYS-Workbench to obtain more accurate spindle temperature field distribution and thermal deformation. Based on a finite element emulation result, the spindle temperatures in different positions and the spindle thermal deformations are analyzed at different rotational speeds by utilizing the Spearman rank correlation analysis, and spindle thermal key points are found out, so that references are provided to spindle thermal error tests and thermal error compensation. Finally, a thermal error compensation model is built up by utilizing a least squares method according to the key point temperature of the spindle and the thermal errors in the practical tests. Based on the thermal error compensation model, the spindle thermal error compensation is carried out by combining with thermal error compensation strategies of a numerical control system of the machine tool.
Owner:XI AN JIAOTONG UNIV +1

Wind and photovoltaic complementary power generation system reliability evaluation method based on Copula theory

The invention discloses a wind and photovoltaic complementary power generation system reliability evaluation method based on a Copula theory. The method comprises the following steps of: (1) determining the power probability distribution of a wind power station and a photovoltaic plant; (2) respectively performing integral operation on the power probability distribution fWT(P1) and fPV(P2) of thewind power station and the photovoltaic plant, and calculating the accumulative power probability distribution of the wind power station and the photovoltaic plant; (3) calculating Kendall rank correlation coefficients of the power of the wind power station and the photovoltaic plant; (4) calculating a correlation parameter theta of a Frank Copula function; (5) forming a simultaneous equation through a formula (2) and a formula (4) to obtain the joint probability density of the random variables P1 and P2; and (6) acquiring the accumulative probability distribution of the wind and photovoltaiccomplementary power station through integral operation according to a joint probability density function of the power of the wind power station and the photovoltaic plant, forming an off-the-line table of the power of the wind and photovoltaic complementary power station through the accumulative power, and establishing a reliability model of the wind and photovoltaic complementary power station. According to the method, the reliability of the wind and photovoltaic complementary power generation system can be accurately evaluated.
Owner:CEEC JIANGSU ELECTRIC POWER DESIGN INST +1

Method for improving computing precision of rock fracture parameters

The invention provides a method for improving computing the precision of rock fracture parameters, for performance evaluation and drilling of oil and gas reservoirs in oil exploration. The method comprises the following steps of: working out fracture directions and the fracture density by using more than two seismic attributes for uniformization treatment, computing the coefficients of rank correlation of the fracture directions in pairs to obtain the rank correlation and fracture density coefficient, and if the correlation coefficient is over 0.9, determining that the density or direction is the density or direction with highest precision; otherwise, computing absolute error values of the fracture directions corresponding to all attributes at the well point, and sorting the absolute error values according to an order from small to large; computing the coefficients of rank correlation of the fracture density corresponding to the attributes and the coherency attributes, sorting the coefficients of rank correlation according to an order from small to large, and finally computing the fracture directions with the highest precision. The method can ensure the leading position of basic attributes and correct the final result to varying degrees according to the data quality so as to improve the forecast precision by using the existing information.
Owner:BC P INC CHINA NAT PETROLEUM CORP +1

Segmented self-adaptive regularized matching pursuit reconstruction method based on threshold

InactiveCN103746703ABuild accuratelyHigh accurate reconstruction rateCode conversionCorrelation coefficientReconstruction method
The invention relates to the technical field of compression perception and specifically relates to a segmented self-adaptive regularized matching pursuit reconstruction method based on a threshold. The method includes: setting initial state values of different parameters in a sparse signal reconstruction process; calculating the inner products of an iterative allowance r and each column of a sensing array Phi, that is correlation coefficients; finding atoms which satisfy a condition in the sensing array; storing in a subscript set J; ranking correlation coefficients of atoms corresponding to subscripts in the subscript set J from large to small; updating a support set which represents original signals; performing signal approximation through adoption of a least square method and updating the allowance; and performing iteration determination. The segmented self-adaptive regularized matching pursuit reconstruction method based on the threshold combines segmented self-adaptive atom selecting and regularization ideas. The method does not need sparseness as a prior condition in a signal reconstruction process and is self adaptive to approximation sparseness information and capable of constructing the support set accurately and completing precise signal reconstruction and the precise reconstruction rate is higher than the prior method of the same kinds so that the method is higher in practical applicability.
Owner:HARBIN ENG UNIV

Wind speed modeling method for large-sized wind power plant in mountainous area

The invention discloses a wind speed modeling method for a large-sized wind power plant in a mountainous area. The method comprises: 1, sampling historically recorded wind speed of the wind power plant, and calculating parameters c and k of wind speed Weibull distribution of each fan group of the wind power plant; 2, calculating a rank correlation coefficient Rho Rr of each fan group in the wind power plant, and constructing a historical wind speed rank correlation coefficient Rr of the wind power plant; 3, calculating related wind speed normal Copula functions of the wind power plant to obtain a joint probability distribution function, defined in the specification, of modeled and predicted wind speed with correlation, and edge probability distribution functions u1 to un of wind speed of fan groups; and 4, performing equiprobable reverse transformation of the Weibull distribution parameters c and k on the edge probability distribution functions of the wind speed of the fan groups to realize wind speed prediction. According to the method, the technical problem that a characteristic that wind speed in a wind power plant has correlation cannot be truly and effectively reflected, electric power distribution and safety operation of a power system are influenced due to direct influence of the correlation of the wind speed in the wind power plant on output of the wind power plant, and the like in the prior art are solved.
Owner:POWER GRID PLANNING RES INST OF GUIZHOU POWER GRID CO LTD

Universal no-reference image quality evaluation method based on multi-task convolutional neural network

InactiveCN110189291AImage representation is accurateGood performance on image evaluation tasksImage enhancementImage analysisDictionary learningData set
The invention discloses a no-reference image quality evaluation method based on a multi-task convolutional neural network, and belongs to the field of image perception. The method specifically comprises the following steps: step 1, extracting a plurality of image blocks with fixed sizes from each image of a manually labeled image quality data set, and each image block corresponding to two labels,which are respectively a degradation category of the image and a degradation degree of the image, so as to form a training set; step 2, constructing a convolutional neural network model based on dictionary learning; step 3, training the constructed convolutional neural network model by using the training set, and determining parameters of the convolutional neural network model after the training is finished; and step 4, during application, inputting the to-be-scored pollution image into the trained convolutional neural network model to obtain a corresponding image quality score. Compared witha traditional method, the method is higher in consistency with subjective evaluation in the field of non-reference image quality evaluation, and key indexes such as the Spearman rank correlation coefficient and the Pearson linear correlation coefficient are obviously improved.
Owner:ZHEJIANG UNIV

Multi-component converted wave fracture prediction method based on rank correlation analysis

ActiveCN107678063AProminent distributioHighlight developmentSeismic signal processingWindow selectionComputer science
The invention provides a multi-component converted wave fracture prediction method based on rank correlation analysis. The predication method includes steps of selecting a calculation time window, intercepting the radial component and the transverse component of a to-be-handled sampling point according to the calculation time window; performing rank correlation analysis on the to-be-handled sampling point and acquiring a maximal rank correlation coefficient; judging whether the to-be handled sampling point has fracture development and determining the location of the fracture development; separating the radial component and the transverse component to the to-be-handled sampling point judged to have fracture development and acquiring a quick transverse wave and a slow transverse wave; calculating the anisotropy coefficients according to the time difference between the quick transverse wave and the slow transverse wave; repeating the steps from calculation time window selection to anisotropy coefficient calculation for the next to-be-handled sampling point until calculation on seismic data is completed. According to the invention, judgment is made on calculation results by adopting adiscrimination method, so that areas with distinctive non-development of fractures are removed and accuracy in fracture development statistics is improved.
Owner:BC P INC CHINA NAT PETROLEUM CORP +1

Non-calibration object registering method for pre-operation three-dimensional images and intra-operative perspective images

The invention relates to a non-calibration object registering method for pre-operation three-dimensional images and intra-operative perspective images. The method includes a first step of obtaining a series of three-dimensional images before an operation, generating N DRR images according to operation needs and obtaining the posture coordinate W of each image, a second step of obtaining an X-ray perspective images of different angles during operation through an X-ray machine on a C-shaped arm, a third step of conducting normalization processing for a DRR image i and the X-ray perspective images, a fourth step of employing a non-linear histogram matching algorithm, a fifth step of comparing rank correlation similarity of the DRR images i and the X-ray perspective images, and obtaining posture parameters of the X-ray perspective images and going to the next step if the two sets of images match with each other, otherwise, extracting the information of a DRR image i+1, and returning back to the third step, and a sixth step of conducting accurate registering for the pre-operation three-dimensional images and the X-ray perspective images based on the multi-resolution mechanism and gradient difference correlation, and outputting the image after accurate registering. Harm to a patient during an operation can be reduced.
Owner:BEIJING TINAVI MEDICAL TECH

Machine tool cross beam optimal design assessment method adopting combination weighing-grey correlation

The invention discloses a machine tool cross beam optimal design assessment method adopting combination weighing-grey correlation. The machine tool cross beam optimal design assessment method comprises the following steps that three-dimensional modeling is conducted on original cross beams, and static and dynamic characteristics of the original cross beams are analyzed to determine optimized factors and assessment indexes of the cross beams; cross beams of multiple structural schemes are designed, and several optimal schemes are preliminarily screened by analyzing and comparing static parameters of the cross beams; for the preliminarily screened schemes, cross beam rib plate structures, rib plate thickness and guide rail supporting rib plate inclination angles on the cross beams serve as test factors, the levels of the factors are determined, and an orthogonal test table is selected to conduct a simulation test on parameter combinations; simulation data is analyzed and processed by adopting a grey correlation method and a combination weighing method to obtain an optimal scheme; properties of the cross beams before and after optimization are compared to determine the reasonability of the optimal design parameter combinations. The machine tool cross beam optimal design assessment method makes a final analysis result real and reliable and accord with objective reality.
Owner:NANTONG UNIVERSITY

Short-period load prediction method for microgrid based on SPSS and RKELM

The invention proposes a short-period load prediction method for a microgrid based on SPSS and RKELM, and the method comprises the steps: (1), carrying out the online data collection, and periodicallyupdating a historical database; (2), carrying out the preprocessing of historical data, and extracting load sample features; (3), constructing an offline load prediction model; (4), screening a historical sample similar to a to-be-predicted point precursor load as an online training sample through SRC (Spearman Rank Correlation); (5), calculating a load prediction value at a future moment according to the online training sample and the offline load prediction model. The method employs a rapid RKELM (Reduced Kernel Extreme Learning Machine), a chaos particle swarm optimization algorithm and the SRC, and achieves the building of a prediction model comprising offline parameter optimization and an online load. Through the periodic updating of model parameters, the method guarantees the timeliness of an algorithm, reduces the complexity of online prediction and calculation, reduces the storage quantity of historical data, reduces the calculation cost, and can achieve the more accurate prediction of the short-period and super-short-period loads of the microgrid.
Owner:SOUTH CHINA UNIV OF TECH

Method for evaluating NOR and NAND flash memory performance

The invention discloses a method for evaluating NOR and NAND flash memory performance. The method is used for solving the technical problem of poor comprehensive operational capability of a present flash memory performance evaluation method. According to the technical scheme, the method comprises the following steps: firstly, testing a read-write speed U1 of the flash memory, and then testing the mounting time U2 of the flash memory, the average loss U3 of the flash memory, the memory consumption U4 of the flash memory, the hardware read/write speed U5 of the flash memory, the erasing speed U6 of the flash memory, the erasing energy consumption U7 of the flash memory, the hardware read/write energy consumption U8 of the flash memory and the file system energy consumption U9 of the flash memory in turn, and finally adopting a rank correlation analysis method for comprehensively evaluating the indexes from U1 to U9. The comprehensive evaluation for 9 indexes related to read-write, loading, erasing and energy consumption of the flash memory is adopted; the read-write speed, the file system operation capacity and the energy consumption related to the performance test for the flash memory are estimated; a corresponding index system is supplied for the three aspects of file system, hardware driving and energy consumption; and a rank correlation method is adopted for carrying out comprehensive evaluation and calculation, so that a test result can reflect the comprehensive capacity of the flash memory in the aspects of read-write, loading, erasing and energy consumption.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Method for optimizing parameters of contact line and pantograph based on sensitivity analysis

The invention discloses a method for optimizing parameters of a contact line and a pantograph based on sensitivity analysis. According to bow-net contact pressure during running of a high speed train, the existing problem is analyzed, level value design of the parameters is carried out through central composite design, and multi-factor and five-level parameters are obtained; an Spearman rank correlation coefficient method is adopted to compute correlation coefficients between the parameters of the contact line and the pantograph and the contact pressure to judge the correlation; and an Sobol method is adopted to compute sensitivity coefficients of the parameters of the contact line and the pantograph about the contact pressure, judge the impact of the parameters on the contact pressure and determine an optimization order of the parameters when the bow-net parameter optimization is carried out, after each index meets relevant standard requirements, optimization is ended and all bow-net parameter values are output. The method has reasonable optimization, and the parameters of the contact line and the pantograph can be adjusted quickly and reasonably, so that the contact pressure of the parameters of the contact line and the pantograph can be controlled reasonably.
Owner:BEIJING JIAOTONG UNIV

Prediction of cavity size in the packed bed systems using new correlations and mathematical model

It has been reported in the literature that raceway measurement made during the decreasing gas velocity is relevant to operating blast furnaces. However, no raceway correlation is available either for decreasing or increasing gas velocity which is developed based on a systematic study and none of the available correlation take care of frictional properties of the material. Therefore, a systematic experimental study has been carried out on raceway hysteresis. Based on experimental data and using dimensional analysis, two raceway correlations, one each for increasing and decreasing gas velocity, have been developed. Also, in the present study the effect of stresses has been considered along with pressure and bed weight terms mathematically. These three forces are expressed in mathematical form and solved analytically for one-dimensional case, using a force balance approach. Based on the force balance approach a general equation has been obtained to predict the size of the cavity in each case, i.e., for increasing and decreasing velocity. Results of these correlations and model have been compared with the data obtained from literature on cold and hot models and plant data along with some experimental data. An excellent agreement has been found between the predicted (using correlations and model) and experimental values. The proposed theory is applicable to any packed bed systems. It has been shown that hysteresis mechanism in the packed beds can be described reasonably taking into consideration the reversal of sign in frictional forces in increasing and decreasing velocity cases.
Owner:COUNCIL OF SCI & IND RES
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