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89 results about "Method of characteristics" patented technology

In mathematics, the method of characteristics is a technique for solving partial differential equations. Typically, it applies to first-order equations, although more generally the method of characteristics is valid for any hyperbolic partial differential equation. The method is to reduce a partial differential equation to a family of ordinary differential equations along which the solution can be integrated from some initial data given on a suitable hypersurface.

Modeling method of characteristics of population space-time dynamic moving based on multisource data fusion

The invention provides a modeling method of the characteristics of population space-time dynamic moving based on multisource data fusion. The modeling method comprises: A. inputting map data, mobile phone locating data and floating vehicle data into a system and managing data organization according to requirements; B. establishing a spatial analysis model of the characteristics of population moving based on the mobile phone locating data and the floating vehicle data; C. applying the spatial analysis model of the characteristics of the population moving to carry out multisource data fusion of the map data, the mobile phone locating data and the floating vehicle data to obtain integrated information of the characteristics of the population moving; and D. analyzing the characteristics of various population moving according to the integrated information of the characteristics of the population moving and publishing an analyzed result by the geographic information system. The modeling method can acquire data of urban population space-time dynamic distribution and moving characteristics with large data amount, high quality and space-time characteristics, obtain basis of accurate population distribution and population moving characteristics, and provide decision-making supports for urban planning, land use planning, transportation planning and the like.
Owner:SHENZHEN INST OF ADVANCED TECH

Optical fiber vibration identification system based on phi-OTDR technology and optical fiber vibration identification method thereof

The invention provides an optical fiber vibration identification system based on a phi-OTDR technology and an optical fiber vibration identification method thereof. The monitoring distance of the system is greatly enhanced through a dual-path detection structure; the adaptability of the system for environmental noise changes is enhanced by the method of characteristic threshold dynamic updating, and a vibration event is accurately positioned; background noise in signals can be greatly reduced through spectral subtraction noise reduction under the condition of maintaining the signal characteristic and energy of the vibration signals, and the signal-to-noise ratio of the signals and the sensitivity of system detection can be enhanced; and multi-characteristic parameter mode identification is performed on the vibration signals from the time domain and the wavelet domain so that the influence of other complex time-dependent interference noise can be effectively avoided, the correct rate of vibration event detection and vibration type classification can be enhanced, the false alarm rate of the system can be reduced, the detection performance of a vibration detection system based on the OTDR technology in the actual complex noise environment can be enhanced, and the national major project application requirements in the aspects of boundary safety and long-distance pipeline safety can be met.
Owner:ZHEJIANG UNIV

Asymmetric supersonic velocity spray pipe and design method thereof

The invention provides an asymmetric supersonic velocity spray pipe and a design method thereof. The design method of the supersonic velocity spray pipe comprises the following steps: according to an inlet coordinate and a throat area, determining a subsonic velocity segment curve; according to the subsonic velocity segment curve and a throat radius of curvature, determining a characteristic line in a transonic velocity area; according to one end point of the characteristic line and a corresponding supersonic velocity area outlet end point, determining a first wall surface curve; and according to an initial characteristic line and the Mach number distribution of the first wall surface curve, determining a second wall surface curve by mass conservation with a characteristic line method. With the design method of the asymmetric supersonic velocity spray pipe, concentrated compression wave in the flow field of the asymmetric supersonic velocity spray pipe can be reduced or eliminated, the quality of the flow field of the spray pipe is greatly improved, equipment performance is improved, and research funds can be saved. According to the asymmetric supersonic velocity spray pipe disclosed by the invention, the design method of the asymmetric supersonic velocity spray pipe is adopted.
Owner:NAT UNIV OF DEFENSE TECH

Personnel reidentification method based on deep learning and distance metric learning

The invention relates to the field of the identification method, and particularly relates to a personnel reidentification method based on deep learning and distance metric learning. The identificationmethod comprises the steps that (1) a pedestrian target detection method based on the convolutional neural network is adopted to process the video data so as to detect the pedestrian target in the video; (2) the initial characteristics of the pedestrian target are coded by using an unsupervised RBM network through the bottom-up mode so as to obtain a visual dictionary having sparsity and selectivity; (3) supervised fine adjustment is performed on the initial visual dictionary by using error back propagation so as to obtain the new image expression mode of the video image, i.e. the image deeplearning representation vector; and (4) the metric space closer to the real semantics is acquired by using the distance metric learning method of characteristic grouping and characteristic value optimization, and the pedestrian target is identified by using a linear SVM classifier. The essential attributes of the image can be more accurately expressed so as to greatly enhance the accuracy of pedestrian reidentification.
Owner:江苏测联空间大数据应用研究中心有限公司

Design method for three-dimensional internal rotary inlet based on complete flow direction suction

ActiveCN106250597AImprove self-starting performanceExcellent self-startGeometric CADTurbine/propulsion air intakesLow speedMethod of characteristics
The invention discloses a design method for a three-dimensional internal rotary inlet based on complete flow direction suction, and relates to inlet boundary layer suction. The method comprises the following steps of solving an axial symmetric basic flow field by adopting a characteristic line method according to design requirements; generating a three-dimensional internal rotary inlet compression profile by applying a streamline tracing method; calculating displacement thicknesses of conical sections of different positions of the shoulder of the three-dimensional internal rotary inlet according to a displacement thickness formula; designing a complete flow direction suction opening based on the inlet compression profile and the displacement thicknesses; constructing a new inlet exit shape by the complete flow direction suction opening, and performing unidiameter backward stretching to obtain a three-dimensional internal rotary inlet separation section; and obtaining the three-dimensional internal rotary inlet which is capable of eliminating low-speed and low-energy airflow of a boundary layer completely in a flow direction and does not influence flowing characteristics of high-speed and high-energy airflow in the inlet. The self-opening performance of the three-dimensional internal rotary inlet can be remarkably improved. The low-energy flow of the boundary layer can be completely eliminated and the flowing characteristics in the inlet are not influenced.
Owner:XIAMEN UNIV

Testing method of characteristics of sound vibration and point vibration of piano sound board and special equipment thereof

The invention discloses a testing method of characteristics of sound vibration and point vibration of a piano sound board and special equipment thereof. The testing method of sound vibration and point vibration comprises the steps of applying the modern technologies, such as magnetostriction, audio measurement, vibration measurement, computer frequency spectrum analysis and the like in the manufacturing process of the piano sound board, utilizing a sound sensor and a vibration sensor for respectively detecting an integral sound vibration signal of the sound board and a point vibration signal of a local area, then analyzing the comprehensive vibration characteristics of the sound board through a computer frequency spectrum system, and further realizing the oriented tuning of the sound board. The method has the advantages of high sensitivity, fast and accurate measurement and strong intuition, and can effectively control the sound of the sound board and provide the scientific method andmeans for objective identification, evaluation and tuning of the acoustic quality of the piano sound board.The special equipment for testing of the characteristics of the sound vibration and the point vibration of the piano sound board mainly comprises an audio sweep signal generator, a magnetostrictive audio transducer, a measurement microphone, an accelerometer, a data acquisition card, professional frequency spectrum analysis software, a computer and the like.
Owner:王宏伟

Supersonic velocity spray pipe with shared throat part and design method of supersonic velocity spray pipe

The invention provides a supersonic velocity spray pipe with a shared throat part and a design method of the supersonic velocity spray pipe. The design method of the supersonic velocity spray pipe with the shared throat part comprises the following steps of: determining a subsonic velocity segment curve according to an entrance geometric parameter and the area of the throat part; determining an initial characteristic line emitted from the throat part according to the subsonic velocity segment curve and the maximum divergence angle; determining a curve of a wall surface in the shared segment of the throat part by a characteristic line method according to the initial characteristic line and the mach number of the wall surface in the shared segment of the throat part; and setting the mach number distribution of an axial line in the downstream of the curve on the wall surface in the shared segment of the throat part according to the structural design requirement of the supersonic velocitysegment of the spray pipe, and determining a non-throat part curve in an iteration way by the characteristic line method. By the design method, the parameter of an exit flow field of the spray pipe can be changed by sharing the throat part and exchanging an expansion segment; the processing cost of the throat part of a wind tunnel spray pipe is saved; and the uniformity of the exit flow field of the spray pipe can be ensured and the quality of a wind tunnel flow field can be improved while the throat part is shared. According to the supersonic velocity spray pipe with the shared throat part, the design method of the supersonic velocity spray pipe with the shared throat part is utilized.
Owner:NAT UNIV OF DEFENSE TECH

Whole-process steam turbine modeling and recognizing method of actual characteristics of parameters changing with working conditions

ActiveCN106682376AAccurate Power ResponseAccurate Pressure ResponseGeometric CADSpecial data processing applicationsProcess dynamicsMathematical model
The invention discloses a whole-process steam turbine modeling and recognizing method of actual characteristics of parameters changing with working conditions. The method mainly includes: 1), applying a mechanism analyzing method to build a whole-process steam turbine mathematical model in consideration of characteristics of parameters changing with unit running conditions; 2), putting forward an acquiring method of characteristics of key parameters changing with working conditions on the basis of an on-site experiment method; 3), putting forward a steam turbine system model parameter recognizing method based on a particle swarm algorithm-steam turbine system model. A solution is provided for the problem that a steam turbine model under the condition of dynamic stimulation great disturbance of a power system is difficult to reflect actual unit active power response characteristics, power output characteristics of a steam turbine under the condition of great disturbance in whole-process dynamic stimulation of the power system can be stimulated, analysis accuracy of the power system is improved, and safe and stable running of a power grid is guaranteed.
Owner:STATE GRID HENAN ELECTRIC POWER ELECTRIC POWER SCI RES INST +4

Method for dividing and sticking horizons by using X-ray fluorescence spectral characteristics of rock debris

The invention discloses a method for dividing and sticking horizons by using X-ray fluorescence spectral characteristics of rock debris. The method comprises the following steps: a, familiarizing stratigraphic characteristics of a working area and division standards of stratum; b, determining a marker bed or an auxiliary marker bed for dividing and sticking horizons; c, determining characteristic elements with different lithologies; d, establishing an XRF (X-ray Fluorescence) section model in the working area; e, performing lithological horizon homing by using XRF spectral characteristics of the rock debris; f, drawing an XRF profile map of the rock debris according to analyzed XRF data of the rock debris at a well section; g, dividing horizons by using a curve characteristic method of characteristic elements with different lithologies, a curve intersection method, an element ratio method and a characteristic element method. According to the method, the conditions that a new drilling process and a new drilling technology limit an existing lithology identification technology and affect drilling fluid materials are avoided, change characteristics of formulation lithology can be objectively and accurately reflected, and microscopic verification and quantification of the lithologic interpretation are realized.
Owner:CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD

Method and device for classifying text

The invention discloses a method for classifying texts. The method comprises: establishing a training text set, generating a first text classifier and a second text classifier; preprocessing to-be-classified texts, using a replacement string to replace text noise in the texts; counting the probability of the replacement string, when the probability is larger than or equal to a filtering threshold value of the first text classifier, the to-be-classified texts being divided into common texts; when the probability is smaller than the filtering threshold value, performing word segmentation on the to-be-classified texts which is preprocessed; establishing a first text representation, a second text representation, and a third text representation of the to-be-classified texts; based on a method of characteristic representation, calculating first text characteristic representation of the first text representation, second text characteristic representation of the second text representation, and third text characteristic representation of the third text representation; and based on the first text characteristic representation, the second text characteristic representation, and the third text characteristic representation, using a second classifier to classify the to-be-classified texts. Also disclosed is a device for classifying texts.
Owner:HITACHI LTD

Leakage detection method for large complex natural gas pipeline network system

The invention discloses a leakage detection method for a large complex natural gas pipeline network system. The method comprises the steps of 1, performing static simulation to obtain a pressure along a line, flow and initial distribution of temperature in a pipeline; 2, performing online simulation to obtain a pressure along the line, flow and real-time distribution of temperature in the pipeline; 3, performing parameter learning, and proposing a pipeline transient flow state space model-based pipeline parameter real-time online estimation and learning model based on an implicit method and characteristic line method-based gas pipeline dynamic simulation state space model according to a sensitivity analysis theory; and 4, performing leakage detection, calculating a deviation between a simulated pressure and an actually measured pressure of each pressure measurement point, and realizing leakage state identification and diagnosis of the large complex oil and gas pipeline system through correlation analysis of simulated and actually measured pressure deviation distribution. The limitation of sectional detection is broken through, and a leakage detection system for the CPM (Computational Pipeline Monitoring)-based large complex natural gas pipeline system is established.
Owner:CHINA PETROLEUM & CHEM CORP +1

Axisymmetric continuous variable Mach spray pipe and wall determining method thereof

The invention discloses an axisymmetric continuous variable Mach spray pipe and a wall determining method thereof. The wall determining method comprises the steps as follows: a rotation axis, a known wall curve, a plug wall curve matched with the known wall curve and the relation curve of the precession distance of a plug mechanism and Mach are determined according to the structural design requirements of the spray pipe; the corresponding wall curve to be obtained is determined by utilizing a characteristic method according to the relation curve of the precession distance of a plug mechanism and Mach when the plug mechanism is in the current position; the position of the plug mechanism on the rotation axis is changed, and the wall curves to be obtained in various sections are determined step by step; in addition, a wall of the axisymmetric continuous variable Mach spray pipe is determined according to the known wall curve, the plug wall curve matched with the known wall curve and the wall curves to be obtained in various sections. By adopting the wall determining method, the fluid field homogeneity degree of the determined axisymmetric continuous variable Mach spray pipe is less than 1 percent, and is increased by one order of magnitude as compared with the traditional technology; and the sensitivity of Mach on the precession distance can be controlled.
Owner:NAT UNIV OF DEFENSE TECH

Water body modeling method for shallow water equation model with optimized parameters

The invention discloses a water body modeling method for a shallow water equation model with optimized parameters. According to the method, first, a three-dimensional dynamic coordinate system is constructed, and the shallow water equation model with optimized parameters is derived; when the model is solved, a reverse path tracking method and a method of characteristics are combined to solve an advective item in an equation, a vector projection method and a Fourier transformation method are combined to solve the effect of external acting force on a water body, and therefore a velocity field and a height field are updated; next, boundary check is performed, a boundary truncation method is adopted to process mesh points beyond a boundary; and last, the height field is drawn, and a next time period is processed cyclically. Compared with a traditional shallow water equation, when the contact surface between the water body and a solid is excessively steep, a water body model can be constructed more vividly and accurately, and the velocity of average 24.9 frame/second can be reached in the water body modeling simulation process; compared with a traditional method, the velocity is increased by 29.016%, and real-time simulation can be realized basically.
Owner:BEIHANG UNIV

On-line fitting method of characteristic function of discrete control system based on data mining

The invention discloses an on-line fitting method of the characteristic function of a discrete control system based on data mining, and belongs to the technical field of industrial control. The on-line fitting method comprises: step one, obtaining relevant to-be-fitted data and carrying out preprocessing of the data; step two, establishing an artificial neural network model and calculating to obtain a characteristic function curve after training the model; step three, carrying out fold line fitting of the curve obtained in step two to obtain the fold line fitting result of the characteristic function; and step four, according to a new characteristic function curve, carrying out on-line correction of the fitting fold line of the current characteristic function, and ensuring that the correction method can meet the requirements of generating no disturbance during the operation of the discrete control system. The on-line fitting method combines an artificial intelligence method with a numerical calculation method, and has high calculation speed and ideal fitting effects; moreover, the method effectively solves the problems of the characteristic function of the prior discrete control system needs manual calculation and has difficult precise fitting and on-line correction.
Owner:SHANGHAI JIAO TONG UNIV

Slider type Mach-number-variable spray pipe and wall determination method thereof

The invention provides a slider type Mach-number-variable spray pipe and a wall determination method thereof. The wall determination method of the slider type Mach-number-variable spray pipe comprises according to structural design requirements of the spray pipe, determining partial wall curve as a fixed wall curve, and determining a slider guide rail wall line, a slider wall curve, and a relation curve between a procession distance and an exit Mach number; according to the relation curve between the procession distance and the exit Mach number, using a characteristics method to determine a corresponding wall curve to be solved when the slider is located in a current position; changing the slider position on the slider guide rail to enable a currently designed Mach number value interval to cover all values of the exit Mach number in the relation curve between the procession distance and the exit Mach number, and determining each section of the wall curve to be solved; and determining the wall curve of the spray pipe according to the slider guide rail wall line, a fixed wall curve, the slider wall curve, and each section of the wall curve to be solved. The exit fluid field of the spray pipe determined with the method is high in uniformity, and the exit Mach number can well accord with an exit Mach number given in advance.
Owner:NAT UNIV OF DEFENSE TECH

High-supersonic-speed internal contraction air intake channel gradually changed from convex shape into round shape and design method thereof

ActiveCN108301926ANo flow coefficient lossIncrease the degree of overflowGas turbine plantsJet propulsion plantsShock waveMethod of characteristics
The invention discloses a high-supersonic-speed internal contraction air intake channel gradually changed from the convex shape into the round shape and a design method thereof. According to the high-supersonic-speed internal contraction air intake channel gradually changed from the convex shape into the round shape, the middle of a lip plate of the air intake channel gradually changed from the convex shape into the round shape is provided with an upward protruding part, an inlet of the air intake channel is in the convex shape, and the air intake channel contracts towards an outlet, is gradually changed into the round shape and then is connected with a circular-cross-section equal straight isolation section equal to the air intake channel in area; an internal conical surface controllablein compression surface Mach number, a central body of a uniform flow movable angle variable cross section, and a datum flow field are obtained through a characteristic line method, and reverse streamline tracing is conducted according to the round outlet of the air intake channel; the upward protruding part is additionally arranged at the inlet based on the original rectangle and extends to the central body, accordingly, matching is conducted on the natural outlet area obtained through convex inlet streamline tracing, and a round outlet of which the area is equal to that of the convex inlet isobtained; and after streamline fitting and boundary layer correcting are conducted, the final air intake channel changed from the convex shape into the round shape is obtained. According to the high-supersonic-speed internal contraction air intake channel gradually changed from the convex shape into the round shape and the design method thereof, on the premise that design point shock wave sealingis ensured, starting of the internal contraction air intake channel is substantially improved through the upper convex overflow design measure designed by the streamline tracing technology.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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