1065results about How to "Improve calculation accuracy" patented technology

A system and method for identifying a pointing organ or a pointing device in a field of imaging of a 3-D imaging system and for calculating a line of pointing relative to this organ or device are disclosed. The method and system may be used to enable a user to communicate with computer programs, such as computer games, 3-D design programs and the like. The method and system may further employ a trigger-like mechanism to identify a movement of a user that may be interpreted as trigger activation.

The invention belongs to the field of artificial intelligence technology and particularly discloses an intelligent question-answering system for tax consultation service. The system comprises a terminal device where an Android operating system is installed and a computer; an application software program is installed in the terminal, wherein the application software comprises a voice conversion module and a question return module; a service software system is installed on the computer, wherein the service software system comprises a question understanding module and a question retrieval module; when the system operates, the voice conversion module converts voice data output by a user into text data, semantic understanding is performed through the question understanding module, the question retrieval module is used for retrieving answers, and a processing result is transmitted to the terminal user through the question return module. According to the system, voice recognition, text classification, similarity calculation and other technologies are used comprehensively to form a method for performing text similarity matching on an incomplete data set in the area of expertise, profound semantic analysis can be performed on questions raised by taxpayers, and meanwhile ceaseless accurate consultation service is provided for mass users to meet the actual requirement for tax consultation.

This system is a computer-based system for analyzing a blood flow at a target vascular site of a subject by means of a computer simulation, having a three-dimensional shape extraction unit, by a computer, for reading a captured image at the target vascular site and generating three-dimensional data representing a shape of a lumen of the target vascular site; a fluid dynamics analysis unit, by a computer, for determining state quantities (pressure and flow velocity) of blood flow at each position of the lumen of the target vascular site by means of computation by imposing boundary conditions relating to blood flow to the three-dimensional shape data; a blood flow characteristic determination unit for determining, from the state quantities of the blood flow determined by the fluid dynamics analysis unit, a wall shear stress vector at each position of the lumen wall surface of the target vascular site, determining relative relationship between a direction of the wall shear stress vector at a specific wall surface position and directions of wall shear stress vectors at wall surface positions surrounding the specific wall surface position, and from the morphology thereof, determining characteristics of the blood flow at the specific wall surface position and outputting the same as a determined result; and a display unit, by a computer, for displaying the determined result of the blood flow characteristic which is graphically superposed onto a three-dimensional shape model.

The invention discloses a monitoring device and a monitoring method for filter screen life of a purifier. The method comprises the following steps: firstly acquiring current air quality information and current wind speed information through a detection module, and then sending to a center control module, computing the rest working life of the filter screen of the purifier through the center control module according to the current air quality information and the current wind speed information, when the rest working life equals to a life limit threshold value, reminding a user of replacing the filter screen of the purifier. Since the air quality is considered in the computation of the life of the filter screen, the computed life is more close to the actual life of the filter screen. The life of the filter screen is progressively decreased per 10 sec according to the current wind speed and air quality, the life of the filter screen can be more carefully estimated, the estimation error is reduced, the computation precision is promoted, and the client loss is reduced.

The invention relates to a pressure-controlled drilling method based on drilling annulus wellbore multi-phase flow computing, which comprises the following steps: obtaining basic parameters for drilling wellbore multi-phase flow computing; determining the variety of fluid in wellbore annulus; considering multi-phase multi-component complex flow factors, and establishing a wellbore annulus internal multi-phase flow control equation group; establishing definite conditions for the multi-phase flow control equation group by combining with technical processes under pressure-controlled drilling different working conditions; carrying out grid division on the time and space domains obtained by multi-phase flow computing; carrying out numerical discretion; solving the wellhead back pressure required by pressure-controlled drilling; and adjusting the wellhead throttling valve based on the computed wellhead back pressure value to realize pressure-controlled drilling. Through the adoption of the method, pressure-controlled drilling can be continued under the condition that the drilling fluid contains gas; the method can be applied to the pressure-controlled drilling process of strata highly containing acidic gases; and the computation accuracy is high, the error is small, the control accuracy of pressure-controlled drilling is improved, and the application range is enlarged.

The invention relates to a global navigation satellite system (GNSS) triple-frequency motion-to-motion positioning method. In the original epoch, the triple-frequency precision single-point positioning technology is adopted to obtain the coordinates of two movable carriers, one of the two movable carries is selected as the reference station for the triple-frequency double-difference position, the triple-frequency double-difference positioning technology is adopted to calculate the baseline component of the two movable carriers and the integer ambiguity resolution of the double-difference carrier phase, and the baseline component of the two movable carriers and the integer ambiguity resolution of the double-difference carrier phase are used as the constraint conditions for the triple-frequency precision single-point positioning in the subsequent epochs to improve the single-point position precision and the convergence speed thereof. The geometry-Base TCAR ambiguity resolution fixation method is adopted to calculate the triple-frequency integer ambiguity resolution. The three irrelevant combination observation values of the triple-frequency non-ionizing layer and the long wave-length and low noise carrier are adopted to detect and repair the cycle slip of the original observation data.

The invention discloses image segmentation method and device, and a method for judging image inversion and distinguishing the front side and the back side of a sternum. The image segmentation method comprises the following steps of: a. preprocessing the input image; b. searching the outline of the target area, and checking the search result of the outline, wherein the process for checking the search result of the outline comprises the following steps of: judging whether the shape abnormity index of the target area in the outline search process is less than or equal to a preset threshold value; if so, accepting the result of the search process; and if not, rejecting the result of the search process; and c. extracting the target area according to the check result. By increasing the check procedure, the invention can enable a user to reasonably distinguish the input image, thereby solving the problem that the image abnormity affects the segmentation.

The invention provides a method for quantitative calculation of thickness of a thin reservoir layer. The method comprises the steps of carrying out three-dimensional multiple coverage data acquisition on the earth's surface to obtain seismic data; carrying out "three-high" processing on the seismic data to obtain three-dimensional post-stack seismic data; conducting logging-seismic calibration by use of logging data, and making clear of the position of a target reservoir layer; carrying out three-dimensional seismic horizon interpretation on the target layer to obtain a time window extraction guide layer; under the guidance of the time window extraction guide layer, giving an appropriate time window according to estimated thickness of the target reservoir layer and seismic data dominant frequency; extracting relative spectral peak frequency increment seismic attributes, and calculating two-way travel time thickness of the target thin reservoir layer; and with P-wave velocity data, converting the time thickness of the target thin reservoir layer into strata thickness. Compared with a current quantitative prediction method for a thin reservoir layer, the method is not subject to an absolute reflection coefficient of top and bottom sides of the thin reservoir layer and does not rely on well data, and the prediction accuracy is high.

The invention discloses a multidimensional collaborative power grid planning method which includes the processes: acquiring geographic environmental information data and calculating comprehensive construction cost data by a rasterized map; building a power grid planning model; and calculating the solution of a power grid planning scheme by an optimal ant colony algorithm according to the acquired data and the power grid planning model. The method includes the steps: comprehensively considering substation locating and sizing, line selection and line corridor selection; and building a multidimensional collaborative power grid planning model considering complicated environmental influence. The multidimensional collaborative power grid planning method can accurately consider the influence of environmental factors on power grid planning. Line construction cost calculation precision is improved, and estimation difficulty is reduced. Catalytic elements are generated according to deviation of the local movement direction and the target movement direction of ants, so that the state transition rule of the ants is improved. The construction cost of lines on a mass raster and a substation is full-automatically and rapidly calculated, and calculation precision and efficiency are remarkably improved.

The invention discloses a data assimilation method for monitoring soil moisture. The method provided by the invention at least comprises an assimilation cycle, and each assimilation cycle comprises the following steps: (1) an ecological process model serves as a dynamic model to stimulate the space distribution state of soil moisture every day, the initial value in the dynamic model is an initial parameter and an initial soil moisture data, and the dynamic model is operated to output simulative soil moisture data; remotely sensed data on the soil surface is performed with inversion to obtain surface layer soil moisture data; the simulative soil moisture data in the remotely sensed data corresponding date is combined with the surface layer soil moisture data obtained by remotely sensed data inversion for data assimilation so as to obtain an optimized ecological process model parameter; (2) the optimized parameter is substituted into the dynamic model in step (1) to operate the dynamic model so as to obtain simulative soil moisture data every day. The method provided by the invention can connect soil moisture variety with vegetable physiological response mechanism by water deficit and stress, which improves the precision of field soil moisture monitoring and drought evaluation and has important application prospect.

The invention discloses a method for calculating dynamic water storage capacity runoff yield in soil freeze-thaw process, and belongs to a hydrological science category in geophysical science categories. The method comprises the following steps of: calculating frozen soil depths at different times in grids of a watershed according to soil temperature distribution; analyzing day-by-day spatial distribution conditions of the frozen soil depths so as to obtain field capacities, distributed along with time, of aeration zones in different grids of the watershed; finding out the maximum field capacities in different grids of the watershed, and calculating the maximum water-holding capacity of the watershed; and calculating a soil freeze-thaw runoff yield of the watershed according to the obtained maximum field capacities in different grids and the maximum water holding capacity of the watershed. According to the method disclosed by the invention, the day-by-day soil freeze/thaw, frozen soil depths and soil temperatures can be simulated according to observed air temperatures, and the day-by-day process of thaw/rainfall runoff can be calculated according to rainfall observation, so that the runoff simulation precision in soil thaw periods in spring is improved, scientific basis is provided for the spring flood prevention decisions, and the gap of frozen soil area runoff yield calculation in the existing home and aboard hydrological models is filled.

The invention provides an engine tail gas after-treatment control system and control method. The engine tail gas after-treatment control system and control method are applied to after-treatment of tail gas. The control system comprises a tail gas post-processor, an engine electric control unit, a diesel injection device, a urea spraying device and a post-treatment electric control single element.The control method is based on the measured values of different sensors and the working condition parameters of an engine, and is based on a pre-calibrated data model to complete the four functions ofDPF active regeneration controlling, DPF accumulated dust cleaning, SCR urea injection controlling and system fault diagnosing. The system is composed of a software system and a hardware system, wherein a transient segmented linear interpolation algorithm is adopted for MAP data, and the calculation precision and the execution efficiency are improved to a great extent. A DPF differential pressuresensor adopts a differential pressure dynamic integral and time-sharing comparison method, so that the condition that the differential pressure value is unstable and the fluctuation is large due to the fact that the differential pressure sensor is influenced by various factors is solved, the robustness of a control strategy of the tail gas after-treatment system is enhanced, and the misjudgment of regeneration is reduced to a great extent, so that the improper active regeneration operation is reduced, and the oil consumption is reduced.

The invention provides a construction method of an evidence chain relation model for a Chinese judgment document. The process of the construction method is shown in the figure and mainly comprises thesteps that text preprocessing is performed on the Chinese judgment document; an XML-formatted file obtained after processing is read, and an evidence chain body set and a fact set are extracted; a keyword set of each evidence chain body and a keyword set of each fact are obtained according to a 4W1H key element extraction strategy; linking in the evidence chain relation model is constructed by calculating key element relevancy to complete model construction; the constructed model is made into an Excel table; and a structured model is displayed as a visual model. Through the method, mainly fora construction task of the evidence chain relation model in argument evaluation of the legal judgment document, according to the characteristics of judgment document arguments and the characteristicsof court document vocabularies, the judgment document preprocessing method is improved, the key element extraction technology is optimized, the correct rate of calculation of linking in an evidence chain is increased, and the method can be effectively used for evaluating the fact argument level of the judgment document.

The invention provides a petroleum-gas prediction method and system based on a Zoeppritz equation approximate expression. The method comprises the steps of collecting logging data and prestack angle gather data of a current target area, extracting seismic wavelets according to the logging data and the prestack angle gather data, obtaining an inversion target function according to the prestack angle gather data, the seismic wavelets and the Zoeppritz equation approximate expression, confirming a target Zoeppritz equation approximate expression according to a first correlation, a second correlation and the Zoeppritz equation approximate expression, confirming longitudinal wave modulus and transverse wave modulus according to the inversion target function and the target Zoeppritz equation approximate expression, confirming fluid factors according to the longitudinal wave modulus and the transverse wave modulus of the stratum of the current target area, and integrally interpreting the fluid factors to obtain a petroleum-gas reservoir prediction result of the stratum of the current target area. Information of the longitudinal wave modulus and information of the transverse wave modulus can be stably gained, precision of the fluid factors is improved, and therefore risks of petroleum-gas reservoir prediction can be lowered.

The invention discloses a method for predicting the energy consumption of a CNC milling machine based on time parameters. The method includes the steps that (a) an energy consumption prediction model is established for the machining process of the CNC milling machine; (b) the no-load power, the additional power, the cutting power and the feeding power of a feed shaft of each component process are detected, and meanwhile the time parameters including the idle time of a main transmission system, the milling time and the working time of the feed shaft are acquired respectively through NC codes; (c) all the obtained power parameters and the obtained time parameters are substituted into the energy consumption prediction model, and the overall energy consumption prediction technological process is correspondingly executed. By the adoption of the method, the energy consumption prediction process of the CNC milling machine can be rapidly and accurately realized only by inputting the cutting data and the time parameters of each process, the method is high in feasibility, and optimization and support can be provided for solving a series of problems of process selection, energy consumption prediction, energy consumption evaluation, energy saving and emission reduction of the machine and the like in workpiece machining process of the CNC milling machine.

The invention aims at providing a sound field rebuilding method. The sound field rebuilding method comprises the following steps that firstly, a sound pressure value of a measuring face in a measuring sound field is measured; secondly, different sound sources are endowed with a certain weight through the centroid method according to the actual positions of the sound sources and the sound intensity, the positions and number of multi-ball virtual source intensities and the position coordinates of each virtual ball are calculated; thirdly, zero filling expanding is carried out on the measured sound pressure value of the measuring face to obtain the sound pressure value of an expanding face of the measuring face; fourthly, a transfer matrix between the sound pressure value of the expanding face of the measuring face and the virtual ball sound pressure is calculated; fifthly, a transfer matrix between the sound pressure value of a rebuilding face and the sound pressure value of the multi-ball virtual equivalent source intensities is built; sixthly, the transfer matrix obtained in the fourth step and the transfer matrix obtained in the fifth step are combined, and the sound pressure value of the rebuilding face is obtained. According to the sound field rebuilding method, multi-ball region two-dimensional fast Fourier conversion algorithm is introduced, a virtual source intensities configuration and the measuring face do not need to be conformal, and the calculation efficiency and calculation precision are very high.

The present invention discloses a ship still water shearing force and bending moment calculating method which comprises the following steps of: establishing three-dimensional photoetching format models of a ship housing and all compartments, i.e. STL models; calculating a floating state of a ship in a random loading state; and calculating a buoyancy distribution curve, a weight distribution curve, a load distribution curve, a shearing force distribution curve and a bending moment distribution curve of the ship. According to the present invention, the floating state of the ship under the random loading condition is calculated on the basis of the STL models; transverse inclination and longitudinal inclination of the ship can be simultaneously calculated; the defect of only calculating a longitudinal inclination angle of the ship in a conventional method is overcome; and calculation accuracy is improved. According to the present invention, on the basis of the ship housing STL model, the buoyancy curves of the ship under the random transverse inclination and longitudinal inclination can be calculated. According to the present invention, the concept of a weight distribution table of the compartments is disclosed and in the calculating process, volume distribution among frames only needs to be interpolated according to a loading height, and not only calculation accuracy can be improved, but also calculation efficiency can be ensured.

The invention relates to a multi-terminal MMC-HVDC (modular multi-level converter high voltage direct current) bipolar short-circuit fault current calculation method. The method includes the following steps that: 1) the equivalent capacitance, equivalent reactance and equivalent resistance of the fault equivalent circuit of a single-terminal MMC-HVDC system converter station are calculated; 2) the discharge current of the converter station which appears after the converter station is latched is calculated; 3) the initial solution of the discharge current of each converter station in a multi-terminal MMC-HVDC system under a condition that the discharge current of the converter station is not affected by other converter stations is calculated; 4) fault current actually passing through each direct-current line in the multi-terminal MMC-HVDC system is calculated; 5) the equivalent resistance and equivalent reactance of the actual fault equivalent circuit of the converter station at each terminal in the multi-terminal MMC-HVDC system are calculated; 6) the discharge current of the converter station at each terminal of the multi-terminal MMC-HVDC system is re-calculated; and 7) the step 4) to step 6) are repeated, and the discharge current value of the outlet of the converter station at each terminal of the multi-terminal MMC-HVDC system is calculated. The multi-terminal MMC-HVDC bipolar short-circuit fault current calculation method has high precision and speed and is of a certain guiding significance for direct current power grid planning and direct current circuit breaker selection.

The invention belongs to the technical field of medical optometry equipment and especially relates to an intelligent portable hand-held vision screening instrument and an optometry method. The instrument comprises an optometry system, a camera shooting system, an integral control system and a wireless communication system which are connected to a central processing unit, wherein the optometry system is composed of a light source, a diaphragm and a lens and is used for emission of the light source, diaphragm isolation and lens transmission; functions of distance and temperature measurement are achieved through combination of an ultrasonic ranging and a temperature sensor; the optometry system can shoot eye images by an infrared lens and a visible light lens; the integral control system executes different modes including a preview mode, a camera shooting mode and a checking mode; the wireless communication system carries out card reading functions of a social insurance card and a medical service card as well as wireless data transmission; and the central processing unit carries out collection and processing of data, image recognition, gray analysis and diopter computation. The intelligent portable hand-held vision screening instrument is connected to an intelligent medical cloud platform by a wireless communication system.

The invention discloses an automatic high-accuracy droplet calculation method of dynamic and static contact angles. The method of the invention is realized by obtaining the droplet edge of a shot clear drop image with a level set method and judging whether the image is a static contact angle, an advancing angle or a receding angle. For a static contact angle image, if the droplet is large in size, an ellipse fitting method should be employed, while if the droplet size and the contact angle are both small, a circle fitting algorithm is chosen. If to calculate an advancing angle, a circle fitting or ellipse fitting algorithm is chosen. If to calculate a receding angle, a polynomial fitting algorithm is employed. By obtaining the tangent of a curve resulting from fitting at a droplet marginal point corresponding to a triplet, two contact angles respectively on the left and right are then obtained. The average of the two contact angles is a final contact angle. According to the method of the invention, dynamic and static contact angles can be calculated rapidly and automatically, with high rate of accuracy.

The invention discloses a velocity ambiguity resolving method based on a coherent frequency agile radar. Through the method, the problem that target detection is not accurate due to distance-velocityambiguity in pulse radar system signal processing is solved. According to the implementation method, a radar pulse echo signal is received; a baseband pulse echo signal sampling matrix is obtained; pulse compression is performed; a radar Doppler vector group is constructed; Doppler offset frequency is determined, and the velocity of a motion target is calculated; velocity ambiguity resolving is performed on the radar pulse echo signal; and target detection is performed through sparse recovery. According to the method, the accurate velocity of the motion target is calculated through the Dopplervector group, velocity phase compensation is performed on the radar pulse echo signal to realize velocity ambiguity resolving, and the target is detected through sparse recovery. The method is low ininterception and resistant to interference, the velocity of the motion target can be accurately calculated, complexity is low, and the problem of distance-velocity ambiguity in pulse radar system signal processing can be solved. The method is applied to the field of radar target detection.

The invention discloses a shortwave transmitting antenna three-dimensional directional diagram aerial mobile measurement system and method. The system comprises a field intensity measurement system which is composed of a loop antenna and a field intensity instrument host and an unmanned aerial vehicle platform and other parts. Computation is performed by a field intensity signal preprocessing module, a standard directional diagram computing submodule, a spatial spectrum processing submodule, a digital beam forming submodule and a transmitting antenna calibration factor computing submodule. The omnidirectional loop antenna is mainly adopted to measure field intensity signals, acquire and store the field intensity signals and preprocess the field intensity signals, then the signals are further processed through the spatial spectrum estimation technology, and finally testing is performed on the unmanned aerial vehicle platform. The index is provided for assessment of a shortwave transmitting antenna directional diagram, and online automatic monitoring of the antenna directional diagram can be realized without influencing the real-time performance and the effectiveness of the shortwave transmitting antenna so that the system and the method have the characteristics of being simple in equipment and convenient to operate.

A method of training a neural network (NN) block for a neural network, including: performing a first quantization operation on a real-valued feature map tensor to generate a corresponding binary feature map tensor; performing a second quantization operation on a real-valued weight tensor to generate a corresponding binary weight tensor; convoluting the binary feature map tensor with the binary weight tensor to generate a convoluted output; scaling the convoluted output with a scaling factor to generate a scaled output, wherein the scaled output is equal to an estimated weight tensor convoluted with the binary feature map tensor, the estimated weight tensor corresponding to a product of the binary weight tensor and the scaling factor; calculating a loss function, the loss function including a regularization function configured to train the scaling factor so that the estimated weight tensor is guided towards the real-valued weight tensor; and updating the real-valued weight tensor and scaling factor based on the calculated loss function.

An integrated touch panel structure and manufacturing method thereof are described. The integrated touch panel structure is integrated by a first sensing layer, a displaying layer, a backlight plate and a composite component layer. The composite component layer includes a second sensing layer and a processing circuit layer. The processing circuit layer further includes a metal area for preventing a touch signal from electromagnetic interference to increase the precision of the touch signal.

The invention discloses a radiation shield calculation method based on coupling of a Monte Carlo method and a characteristic line method. Through the coupling of the Monte Carlo method and the characteristic method, the Monte Carlo method is adopted at a radiation source area complex in geometry for simulation and the non-uniform amendatory characteristic line method is adopted in a shield layer area simple in geometry for simulation to obtain distribution result of radiating particle flux in the shield layer, wherein the Monte Carlo method has the advantages of being capable of accurately simulating the transporting process of particles in multi-dimensional complex geometry, and the characteristic line method has the advantages of being small in limit to calculation models, fast in calculation speed, free of ray effect, and capable of obtaining high-accuracy calculation results. Compared with a traditional shielding calculation method, the radiation shield calculation method based on the coupling of the Monte Carlo method and the characteristic line method are capable of penetrating a shield area deeply to obtain better geometry adaptability, higher calculation efficiency and more accurate calculation accuracy.

The invention discloses a method and a device for detecting cloth flaws based on adaptive orthogonal wavelet transform. Manual eye detection and an original automatic flaw detecting method in which wavelet transform is carried out after a wavelet basis is manually selected are replaced. The defects of traditional manual eye detection, such as low detection speed, low efficiency, false detection and high detection leaking rate are overcome. The problem of the original flaw detecting method based on wavelet transform that the detection precision is low as the wavelet basis is not optimized is solved. The optimal wavelet basis matched with a cloth texture is selected by an improved quantum rotating gate quantum genetic algorithm, the quantum rotating angle is regulated by a dynamic strategy, fine adaptive search is realized, the variety is enriched through introducing mutation operation, and the optimization capability of the algorithnm is improved through combining chaotic search. The flaw detecting method has the advantages of high speed, high accuracy, simplicity in operation and high efficiency and has great application prospects.

The invention provides a measuring wheel used for measuring distance and area and a measuring method thereof, belonging to the technical field of measuring wheel. The invention solves the problem that the traditional measuring wheel can not directly measure area. The measuring wheel used for measuring distance and area comprises a measuring wheel, a wheel frame arranged on the measuring wheel and a handle connected onto the wheel frame, an operational display interface is arranged on the handle, a sensor used for detecting number of turns of rotation of the measuring wheel, the handle is also internally provided with a central processor, the sensor and the operational display interface are all connected with the central processor, the handle is also internally provided with a storage and a geomagnetic field sensor which are connected with the central processor, the central processor is used for receiving a turn number signal and an angle signal, and area surrounded by the way that the measuring wheel rolls for a circle around the ground is calculated according to circumference of the measuring wheel, number of turns of the measuring wheel and steering angle of the measuring wheel, and a result is delivered to the operational display interface to be displayed. The measuring wheel provided by the invention can measure distance and also can directly, rapidly and accurately realize area measurement.

The invention relates to an automatic solar tracking system which tracks the sun accurately in real time and is used for efficiently collecting and using solar energy. The automatic solar tracking device comprises a solar energy photovoltaic array, an adjusting device connected with the solar energy photovoltaic array and used for adjusting the position of the solar energy photovoltaic array, a stand column for supporting the adjusting device and a control system. The adjusting device is composed of a pitch angle adjusting assembly and a position angle adjusting assembly, wherein the pitch angle adjusting assembly is connected with the position angle adjusting assembly through a vertical shaft, the position angle adjusting assembly is arranged on the stand column, and the control system is used for performing closed loop control on the adjusting device. The accuracy in solar tracking of the automatic solar tracking device is smaller than 0.1, the energy consumption only occupies for 0.5% of the electric energy production of the driving photovoltaic array, and the automatic solar tracking system has the advantages of being long in service life, intact in protection function and the like.

The invention relates to a cardinal number estimating method and a cardinal number estimating device under a multi-section query condition of big data. The cardinal number estimating method comprises the following steps of dividing the big data into a plurality of sections in advance according to numerical attributes; establishing a tree-shaped index structure, and utilizing each section as a node of the tree-shaped index structure; acquiring a data source to be written in the tree-shaped index structure, and reversely indexing the data source which supports the section query condition; writing the data source which is reversely indexed into the nodes of the tree-shaped index structure, and respectively writing corresponding portions of the data source into data files and a cardinal number estimator; and querying the nodes meeting the section query condition in the tree-shaped index structure according to the section query condition to obtain the cardinal number estimator in the nodes, and logically processing the cardinal number estimator to obtain cardinal number estimated values. The cardinal number counting efficiency is improved by reducing data calculating precision; the query efficiency is high under the optional multi-section query condition; and the online index data updating efficiency is improved by using a big data incremental updating technology.

The invention relates to a method for measuring railway tank car volume based on computer vision. The method comprises the following steps that the surface of a tank car is provided with a plurality of marking points with identical patterns and coding points with different patterns; a coding point ruler with two different patterns is arranged beside the tank car; a digital camera is adopted to take pictures of the tank car from multiple angles, and an overlapped coding point area is formed between every two adjacent pictures; each picture is input to a computer for image processing, and three-dimensional point coordinates of all coding points and marking points on an image are respectively established according to a computer stereovision three-dimensional reconstruction method based on image sequences so as to acquire three-dimensional point data on the surface of the tank car; three-dimensional shape of the outer surface of the tank car is reconstructed according to the three-dimensional point data; and the tank car volume is calculated according to the three-dimensional shape of the outer surface of the tank car and measured wall thickness of the tank car. The method has the advantages that the method has convenient operation and simple use and solves the problem that the prior standard measuring instrument is susceptible to human-induced factors during operation and has unstable measuring results; moreover, the method ensures that volume uncertainty is less than 0.2 percent.