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59 results about "Geometric standard deviation" patented technology

In probability theory and statistics, the geometric standard deviation (GSD) describes how spread out are a set of numbers whose preferred average is the geometric mean. For such data, it may be preferred to the more usual standard deviation. Note that unlike the usual arithmetic standard deviation, the geometric standard deviation is a multiplicative factor, and thus is dimensionless, rather than having the same dimension as the input values. Thus, the geometric standard deviation may be more appropriately called geometric SD factor . When using geometric SD factor in conjunction with geometric mean, it should be described as "the range from (the geometric mean divided by the geometric SD factor) to (the geometric mean multiplied by the geometric SD factor), and one cannot add/subtract "geometric SD factor" to/from geometric mean .

Hartman wavefront sensor mass center measurement precision optimization method

A method for optimizing centroid measurement precision of Hartmann wavefront sensor includes the steps of: performing threshold processing to pixel data outputted by photoelectric detector; calculating order moment centroid of each subaperture spot using the pixel data of threshold processing, wherein alpha=1, 2, 3......L; calculating repeatedly the order moment centroid of each subaperture spot; calculating the mean value of order moment centroid standard deviation of each subaperture spot; finding out the corresponding minimum order, namely finishing the method for optimizing centroid measurement precision of Hartmann wavefront sensor. Repeatedly calculating alpha order moment centroid of each subaperture spot and obtaining corresponding centroid standard deviation, thereby obtaining the excellent corresponding order which the mean value of all subaperture centroid standard deviation is small, and the filtered high-order centroid algorithm is capable of suppressing more effectively the influence of noise to centroid computational accuracy with the most excellent repeatable accuracy of centroid measurement relative to other each order moment centroid algorithm, thereby improving wavefront reconstruction accuracy.
Owner:INST OF OPTICS & ELECTRONICS - CHINESE ACAD OF SCI

Quantitative evaluation method of aquatic plant species for repairing eutrophication water

The invention discloses a quantitative evaluation method of aquatic plant species for repairing eutrophication water. The quantitative evaluation method comprises the following steps: A, index screening, namely screening to-be-invested water physical and chemical indexes according to eutrophication water characteristics; B, field investigation, namely investing rivers or lakes by adopting a conventional method in a representative region range, recording names of all the aquatic plant species in a quadrat, collecting water samples, and determining physical index of water; C, standard non-dimension disposal calculation, namely classifying the aquatic plants into submerged plants, floating-leaved plants and emergent aquatic plants according to ecotypes, and calculating standard non-dimension disposal data of physical and chemical indexes of water to which each species corresponds according to ecotypes; D, weight giving and total standard deviation calculation, namely giving weight to the physical and chemical indexes, and calculating the general average and total standard deviation of the non-dimension disposal data of each species; E, sorting and quantitative evaluation. The quantitative evaluation method is simple and convenient to operate, fast and accurate, meets the wetland rejuvenation of the rivers, lakes and the like and can be used for promoting the high-efficiency restoration of wetland ecological environments and configuration of functional groups.
Owner:INST OF SUBTROPICAL AGRI CHINESE ACAD OF SCI

Road network evaluation method based on Bayesian model and triple standard deviation criterion

ActiveCN109409713AEffectively identify abnormal eventsMathematical modelsDetection of traffic movementTraffic congestionRoad networks
The invention provides a road network evaluation method based on a Bayesian model and a triple standard deviation criterion. The method comprises the following steps: the traffic indexes in the same period of time of a certain area are counted, and the probability distribution obeyed by the traffic indexes is determined according to the statistical result; calculating parameters of the probabilitydistribution by using a Bayesian model; according to the Bayesian model and the criterion of triple standard deviation, the range threshold of traffic index is calculated, and whether the road network is abnormal or not is judged by comparing the traffic index data with the range threshold of traffic index. If you determine that that road network is abnormal, according to the criterion of triplestandard deviation to calculate the change value and the change rate of network traffic flow, and the change value and the change rate of the traffic congestion index. As an index for evaluating the influence degree of the abnormal event on the road network, the invention can effectively identify the abnormal event of various road networks and the influence degree of the abnormal event on the traffic flow and the traffic congestion of the road network.
Owner:BEIJING JIAOTONG UNIV

A method and system for detecting exposure area in image picture

The invention relates to the field of images, in particular to a method and system for detecting an exposure area in an image picture. Line standard deviation and row standard deviation of the image picture are obtained through calculating respectively, a line gradient corresponding to the line standard deviation and a row gradient corresponding to the row standard deviation are calculated, a weighted coefficient array of a line standard deviation gradient is calculated according to the line gradient, a weighted coefficient array of a row standard deviation gradient is calculated according to the row gradient, the line gradient multiplies the weighted coefficient array of the line standard deviation gradient to obtain a line standard deviation gradient weighting array, the row gradient multiplies the weighted coefficient array of the row standard deviation gradient to obtain a row standard deviation gradient weighting array, and an upper boundary, a lower boundary, a left boundary and a right boundary are determined through the line standard deviation gradient weighting array and the row standard deviation gradient weighting array at last, so that the final exposure area of the image picture is determined. According to the method and system for detecting the exposure area in the image picture, the exposure area in the image picture can be detected rapidly.
Owner:SHENZHEN ANGELL TECH

Shockable rhythms recognition algorithm based on standard deviation of standard grid projection

The invention relates to an electric shock conversion rhythm of the heart recognition algorithm based on the projection standard deviation of a standardization grizzly bar, which is applicable to an instrument or a device for diseases diagnosis. The recognition algorithm comprises steps as follows: S1. Electrical signals are pretreated; S2. The recognition of cardiac arrest rhythm of the heart is carried out on the electrical signals; if the electric signals are of cardiac arrest rhythm of the heart, non electric shock conversion rhythm of the heart is judged; if the electric signals are not of cardiac arrest rhythm of the heart, the following step S3 is carried out; S3. The projection standard deviation of the standardization grizzly bar is calculated; S4. The electric shock conversion rhythm of the heart and the non electric shock conversion rhythm of the heart are distinguished according to the projection standard deviation of the standardization grizzly bar. The recognition algorithm increases sensitivity and specificity of the electric shock conversion rhythm of the heart, simplifies the computational complexity of the recognition algorithm and can be applied to instruments and equipments such as existing ECG monitors and automatic external defibrillators and the like which recognize the electric shock conversion rhythm of the heart according to a body surface electrocardiogram.
Owner:FUDAN UNIV

A passenger transport hub area resident number change trend short-time prediction method based on a kNN algorithm

The invention discloses a passenger transport hub area resident number change trend short-time prediction method based on a kNN algorithm. The method comprises the following steps of obtaining passenger transport hub area resident situation data in real time through a detection system; according to the date characteristics of the to-be-predicted day, selecting m historical samples similar to the to-be-predicted day as predicted sample spaces; preprocessing abnormal data and noise in the historical sample; determining a characteristic space of the to-be-predicted day and the historical sample corresponding to the to-be-predicted time period, calculating an increment ratio standard deviation of the data of the historical sample and the to-be-predicted day on the characteristic space, and finding out k-day data with the minimum increment ratio standard deviation as k adjacent samples; calculating an increment ratio coefficient of k adjacent samples, and predicting the change trend of thenumber of resident people in the region according to the increment ratio coefficient; and calculating a short-time prediction value of the number of resident people in the region by taking the currentnumber of resident people in the region as a reference. According to the method, the change trend of the number of resident people in the short-time area can be accurately predicted by using the historical data, so that a high-precision short-time area resident number prediction result is obtained based on the calculation of the number of resident people in the current area. The method is suitable for the intelligent traffic field.
Owner:SOUTH CHINA UNIV OF TECH +1

Light scattering-based particulate matter concentration detection device

The invention discloses a light scattering-based particulate matter concentration detection device. The light scattering-based particulate matter concentration detection device comprises a particulate matter sampling and cutting device, a scattered light intensity detector, a circuit board, and a display device; the particulate matter sampling and cutting device is connected with the scattered light intensity detector; cut diameter of the particulate matter sampling and cutting device is 2.5+/-0.2<mu>m, and collection efficiency geometric standard deviation is 1.2+/-0.1<mu>m; the circuit board is provided with a data processing module, and a mass concentration conversion coefficient externally arranged interface; the data processing module is connected with the scattered light intensity detector; the mass concentration conversion coefficient externally arranged interface is connected with the data processing module; and the display device is connected with the data processing module. The light scattering-based particulate matter concentration detection device is convenient for people to obtain PM2.5 concentration at a certain time timely, and is capable of providing convenience for air quality PM2.5 index real-time monitoring, and air pollution degree evaluation of certain areas, and providing favorable conditions for active treatment of PM2.5 pollution.
Owner:SHANGHAI QIBAO HIGH SCHOOL

Three-dimensional variational assimilation method for satellite observation data considering channel correlation

ActiveCN109212631AExcellent analysis fieldSolve the problem that the correlation between channels of satellite observation data is not consideredWeather condition predictionPhase correlationMinimization algorithm
The invention provides a three-dimensional variational assimilation method for satellite observation data considering channel correlation. The method comprises the following steps: 1) diagnosing channel correlation and an error standard deviation of satellite observation errors by using posterior information; 2) performing diagonalization decomposition on satellite observation error covariance matrix block; 3) inversing the satellite observation error covariance matrix block; 4) constructing a three-dimensional variational assimilation cost function considering channel correlation of the satellite observation data; 5) solving the constructed cost function and a gradient thereof by using a conjugate gradient minimization algorithm, and obtaining an optimal analysis field; and 6) testing theconvergence of the constructed three-dimensional variational assimilation method. According to the method, the channel correlation and error standard deviation of the satellite observation data are diagnosed by using the posterior information, an observation error covariance matrix in three-dimensional variational assimilation is constructed, and a matrix inversion method is designed, thereby solving the problem that the correlation between satellite observation data channels is not considered in current three-dimensional variational assimilation.
Owner:NAT UNIV OF DEFENSE TECH
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