94results about How to "Avoid measurement bias" patented technology

The invention discloses a measuring method for a carrier gesture of an optical fiber gyro, which comprises determining an initial position parameter and an initial speed value of a carrier through an external device, initially aligning strapdown inertial navigation system of the optical fiber gyro, determining an initial gesture of the carrier which is relative to a navigation coordinate system, obtaining an initial value of a gesture hypercomplex number, determining a gesture renewal cycle H = tm-tm-1, calculating a increment delta phi of rotating vector through collecting a carrier which is output by the optical fiber gyro which is corresponded to an angle speed of the inertial coordinate system, obtaining a gesture renewal hypercomplex number q(H) of the gesture renewal cycle H through a relation of the rotating vector and the hypercomplex number, renewing the gesture hypercomplex number through a renewal equation of the gesture hypercomplex number, calculating a strapdown matrix T that a carrier coordinate system b is relative to a navigation coordinate system n, and obtaining a gesture angle of the carrier which is relative to the navigation coordinate system and the like. The invention solves the problem that a cone effect influences a measuring accuracy of the carrier gesture under a high dynamic environment of a carrier or a high-frequency vibration environment.

The invention discloses a wind tunnel test device for separating a hood of a plane-symmetric hypersonic aircraft. The test device comprises a projectile body model supported by a tail supporting rod of a hypersonic wind tunnel upper mechanism and a cover body model supported by an abdomen of a hypersonic wind tunnel lower mechanism. In an initial state, the cover body model covers the head of theprojectile body model and is separated from the projectile body model without contact; in a test state, the cover body model and the projectile body model are separated and do relatively independent motion; the cover body model adopts a rod-type six-component balance to measure aerodynamic force of the cover body model, and spray pipes are symmetrically arranged on the left and right sides of thecover body model for spray pipe jet flow simulation; the projectile body model adopts a rod type six-component balance to measure the aerodynamic force of the projectile body model; the abdominal support is communicated with a pore plate pressure regulating device. The test device solves the key technical problems of two-stage model relative attitude, two-stage model separation distance adjustment, jet flow simulation, small-size balance design, model connection and the like, improves the jet flow stability of the jet pipe, and reduces the interference of abdominal support.

The invention belongs to the technical field of measurement, and in particular relates to a composite material deflating rate test system with self calibration function and a method. The system comprises a dry pump, a molecular pump, an ultra high vacuum metal angle valve, a getter pump, small pores, a quadrupole mass spectrometer, a vacuum chamber, an extractor gauge, a composite vacuum gauge, a sample room and a capacitance diaphragm gauge. The system combines three material deflating rate test methods, an accumulation method, a dynamic flow method and a double path method, and can test gas flow within the range of 1Pam<3> / s-6* 10<-12>Pam<3> / S ( if the surface area A equals to 6000 cm<2>, deflating rate measurement limit reaches 1*10<-15>Pam<3> / (s cm<2>)). The system covers material deflating rate test range 13 orders of magnitude, adopts a symmetric structure in design, and improves test efficiency and data reliability; besides, the system has function of automatic calibration on the ultra high vacuum gauge, the mass spectrometer and gas micrometeor, and has characteristics of multiple functions and high degree of integration.

A method of monitoring traffic on a road comprising capturing a plurality of images of the road using a camera mounted on a viewing point and associating a time of capture with each image, determining, from the captured images, the positions of the portions of the road surface visible from the viewpoint at the front and rear extremities of the extent of a vehicle in the captured images at two different times; and determining from the positions and the times of the instants at least one characteristic of the vehicle or its motion, such as the vehicle length, speed or a vehicle classification (truck, car, motorcycle, etc).

The invention discloses an automatic continuous dynamic loading method for testing bearing characteristics of an air floating ball bearing. An existing air bearing ball bearing performance detection bearing force cannot be continuously loaded. According to the method, a computer can be used for controlling a loading device through a controller to apply continuously adjustable dynamic loading forceaccording to experimental requirements; any dynamic signal such as a sinusoidal signal, a square wave signal and a slope signal can be set in an experiment process, different bearing forces are generated according to different input signals, and performance parameter measurement of the air floating ball bearing under the action of different bearing forces can be achieved. Moreover, when a constant value signal is input, a loading mechanism outputs a constant continuous loading force, and the dynamic characteristics of the bearing under the constant value loading effect can be measured; on-line detection can be realized through real-time recording and analysis of measured data by the computer. According to the method, the bearing characteristics of the air floating ball bearing in different working states can be simulated.

The invention discloses a heat deformation detection instrument, which comprises a baking oven, wherein a test specimen frame is arranged inside the baking oven. The invention is characterized in that the test specimen frame comprises an upper frame, a lower frame and a load pressure plate arranged between the upper plate and the lower plate, the circumference of the test specimen frame is provided with a guide post used for fixedly connecting the upper plate and the lower plate, the guide post vertically passes through the load pressure plate, the center of the upper surface of the load pressure plate is vertically provided with a load pressure rod, the load pressure rod passes through the upper plate to be connected with a load bearing disc arranged outside the test specimen frame, and a displacement measuring device is arranged on the guide post arranged between the load pressure plate and the lower plate. The invention has the advantages that the measuring deviation caused by deformation inclination of the test specimen, the self weight of a dial indicator and the measured deviaton of the nonuniform heating of the test specimen inside the baking oven can be avoided, and the accuracy of the measuring results can be ensured.

The invention discloses a multimode coupling in-situ microscopic spectral imaging system. The system is composed of an inverted microscope, an exciting light source module, a light path switching module, a spectral imaging and spectrum test module, and refers to a plurality of spectrum and imaging measurement functions in the same micron-order area of a sample, comprising measuring microcell Ramanspectrum and microcell fluorescence spectrum, fluorescence microimaging, microcell transmittance spectrum, transmittance microimaging, microcell reflection spectrum and reflection microimaging. The system has the characteristics that multimode and multidimensional in-situ detection and analysis can be performed on the same microcell of the sample with no need to moving the sample to various kindsof detection equipment; the acquired sample microcell information can be represented in situ, namely that various kinds of information such as the Raman spectrum, fluorescence spectrum and imaging, transmittance spectrum and imaging, reflection spectrum and imaging of the same microcell of the sample can be acquired in real time. Measurement errors caused by transferring of the sample are eliminated, and the reliability of the test result is greatly improved.

The invention discloses a performance detection device and detection method for an air float ball bearing. A prior air float ball bearing performance detection method cannot analyze bearing performance accurately. According to the invention, a pressure measurement hole faces a bearing ball socket. Male threads of a rotary shaft and a pressure guide rod are connected to two symmetric thread holes of a ball respectively. A measurement head of a displacement sensor is arranged on the top part of the ball. When pressure gas is let into the bearing ball socket, a gas membrane gap is formed betweenthe bearing ball socket and the ball so as to support the ball. A loading air cylinder transmits bearing force to the ball through a force sensor, a bearing support and an open-type air float bearingball socket. Pressure gas is let into the open-type air float bearing ball socket, so that a gas membrane gap is formed between the ball socket and the ball. Through combination with a weft-wise rotary table and a warp-wise rotary plate, pressure detection of gas membrane gaps in different positions of the air float ball bearing is realized. According to the invention, a single pressure measurement hole method is adopted, so that flow field distortion caused by multiple pressure measurement holes is avoided. The displacement sensor measures the displacement variation of the ball directly, so that measurement errors caused by indirection measurement can be avoided.

The invention provides a self-adaptive high-precision pressure type water level monitoring and alarming device and method. The water level monitoring and alarming device is fixed on the surface of the outer side wall of a to-be-measured water tank and comprises a pressure sensor, a temperature sensor, an acceleration sensor, a micro-controller unit, a display module connected with the micro-controller unit, a data remote transmission module connected with the micro-controller unit and a power supply module connected with the micro-controller unit, wherein the micro-controller unit is connected with the pressure sensor, the temperature sensor and the acceleration sensor. The self-adaptive high-precision pressure type water level monitoring and alarming device and method solve the problems that an existing fire water tank cannot adjust according to changes of temperature and geographical positions during water level measurement, does not have an alarming function, only has one water level standard, cannot measure the water level accurately and cannot be maintained in time.

The invention discloses a measuring device and a measuring method for surrounding rock deformation of a geotechnical model test. The measuring device comprises a spacing mechanism, an elevating mechanism, a transmission rod, a laser distance measuring mechanism and a laser calibrating mechanism, wherein the elevating mechanism is provided with the spacing mechanism. The transmission rod is arranged at the front end of the spacing mechanism. The front end of the transmission rod is provided with the laser distance measuring mechanism and the laser calibrating mechanism. The axis of the laser transmitter of the laser distance measuring mechanism passes is crossed with the axis of the transmission rod and is perpendicular with the same. The laser transmitter of the laser calibrating mechanism is arranged at the axis position of the transmission rod. The laser mechanism and the laser ranging mechanism are in one plane which is perpendicular with the axis of the transmission rod. According to the measuring device and the measuring method, surrounding rock deformation detection can be efficiently performed by means of the laser distance measuring mechanism, and a high-precision result of a surrounding rock deformation simulation test in a tunnel excavation process is obtained.

The invention discloses a rolled piece width measuring system and method for a rolling mill manipulator. The system comprises laser range finders, laser alignment plates and a PLC data acquisition system, wherein the laser range finders are correspondingly arranged on the two sides of the manipulator, the laser alignment plates are arranged on push heads and are positioned in the longitudinal center positions of the push heads, and the PLC data acquisition system is used for collecting data and remotely transmitting the data. According to the rolled piece width measuring system and method, theinfluence of violent vibration of the manipulator on the precision of a measuring device can be effectively avoided, the stability of the rolling machine manipulator width measuring system is greatlyimproved, and the damage rate of equipment is reduced.

The invention discloses a photonic crystal three-resonant cavity athermalization biosensor. The photonic crystal three-resonant cavity athermalization biosensor comprises a substrate, as well as a plurality of first dielectric cylinders and a plurality of second dielectric cylinders which are vertically arranged on the substrate in a matrix manner, wherein the radiuses of the first dielectric cylinders are r, the radiuses of the second dielectric cylinders are ra, r is not equal to ra, wherein the plurality of second dielectric cylinders are divided into three parts to form a main waveguide and two coupling waveguides respectively, the two coupling waveguides are respectively and symmetrically arranged on two sides of the main waveguide, the main waveguide is linear and is a photonic crystal straight waveguide, the two coupling waveguides are in a shape of quarter turn, the plurality of first dielectric cylinders are filled among the main waveguide and the two coupling waveguides which are mutually independent, three photonic crystal resonant cavities are arranged between the two coupling waveguides and the main waveguide, and the main waveguide and the two coupling waveguides are respectively coupled with the three photonic crystal resonant cavities.

The embodiment of the invention discloses a food processor. The food processor can comprise a heating cup, a heating device and a main control unit, and the heating device is used for heating the heating cup; an over-temperature protection device is arranged on the heating cup, and the food processor is still provided with a temperature sensor; the temperature sensor is connected with the main control unit, which is used for detecting the temperature of the heating cup; the main control unit compares the collected temperature of the heating cup with a preset first temperature threshold value T1; when the temperature of the heating cup is greater than or equal to the preset first temperature threshold value T1, the heating device is controlled to stop heating; the first temperature threshold value T1 is decided by the protection temperature T2 of the over-temperature protection device, and the difference value T2-T1 of the protection temperature T2 and the first temperature threshold value T1 meets that T2-T1 is greater than or equal to 40 DEG C. The food processor solves the problem that the over-temperature protection motion of a fuse link makes the food processor not work normally, dry heating is avoided, the failure rate is reduced, and the user experience is improved.

The invention belongs to a non-destructive testing technology, and relates to a method for determining ultrasonic-acoustic emission detection defect depth of a composite material in the fields of aviation, spaceflight, weapons, ships, metallurgy, steel, traffic, building and the like. The method comprises the following steps: firstly, preparing a thickness calibration test block; secondly, obtaining a thickness reference signal of the thickness calibration test block and checking the defect depth; finally, determining the detected defect depth. According to the method disclosed by the invention, by utilizing a time domain relation between n emission behavior of sound waves and defects in a detected material or the structure and adopting time-domain pulse characteristics of improved ultrasonic-acoustic emission signals, the ultrasonic-acoustic emission longitudinal resolution can be increased, and the defect depth can be more favorably and accurately detected; the method can be more easily realized, is very fast and easy to operate and master, and has better engineering detection and application practicability; the method is more beneficial for quality control of detection results,so that popularization and application of an ultrasonic-acoustic emission method can be more facilitated, and the ultrasonic-acoustic emission method can more favorably play a role in engineering.

The invention provides an accurate measurement method of SO2 emissions after a desulfurization tower of a thermal power plant. The accurate measurement method of the SO2 emissions after the desulfurization tower of the thermal power plant is used for solving a technical problem of accurately measuring the SO2 emissions after flowing through the desulfurization tower of the thermal power plant. Theaccurate measurement method of the SO2 emissions after the desulfurization tower of the thermal power plant comprises the following steps: selecting a rectangular flue section as a measurement planeat a position after the desulfurization tower, and dividing the flue section into m*n measuring points; measuring SO2 concentration at each point; correcting the flow rate of flue gas, and conductingarithmetic average calculation on an actual value of SO2 at each sampling time in a sampling period, that is, obtaining an actual escape ammonia value SO2 in the measurement period. The accurate measurement method of the SO2 emissions after the desulfurization tower of the thermal power plant has the beneficial effects that the measurement method is simple and the measurement result is more accurate.

The invention discloses a connection survey system and method. The survey system comprises two Z-type tripods, reflecting boxes and glass sheets; the Z-type tripods are arranged at the top of a to-be-surveyed vertical pit and provided with a vertical line laser alignment instrument and a total station respectively, and the vertical line laser alignment instrument emits lasers with two colors; thetwo reflecting boxes are arranged at the bottom of the to-be-surveyed vertical pit; the glass sheets are arranged between one Z-type tripod and the vertical line laser alignment instrument as well asbetween the corresponding Z-type tripod and the total station. Through mercury layers in the reflecting boxes, an absolute horizontal plane is provided; through the total station and the lasers with two colors emitted by the vertical line laser alignment instrument, two gravity lines perpendicular to the mercury layers are obtained, in this way, a ground traverse point is introduced into the bottom of the pit, survey deviation is avoided, through the fact that light spots do not overlap since two-color refractive indexes are different, whether or not projecting light rays have atmospheric refraction is detected, accordingly, it is avoided that survey is conducted at in appropriate time, and survey errors are reduced.

The invention provides an air conditioning test device, comprising a wind speed sensor, a support frame and a main bracket. The wind speed sensor is mounted in a support frame. The support frame is movably mounted on the main bracket. The air conditioning test device of the present invention can adjust the position distribution of the wind speed sensor according to the size of the outlet of the air conditioner. The test is simple, convenient, efficient and fast, and the data accuracy is high. The wind speed data of each test area can be read at the same time. The distribution of the wind in each test area is clear and intuitive, at a glance. The overall distribution of the wind outlets can be tested effectively. Furthermore, the laboratory that performs the noise test can be used for windspeed measurement, which saves labor and machine disassembly time. At the same time, measurement deviation caused by multiple disassembly and assembly and different working conditions can be avoided.

The invention discloses unmanned aerial vehicle flight parameter acquisition equipment which can be mounted on an unmanned aerial vehicle. The equipment comprises an attitude acquisition module, a position acquisition module, a processor, a memory, a communication module and a power supply module. In the flight process of the unmanned aerial vehicle, the attitude parameters of the unmanned aerialvehicle are obtained through the attitude obtaining module, and the position parameters of the unmanned aerial vehicle are obtained through the position obtaining module, so that the time consumed forcollecting parameters required by testing can be shortened, and the time consumed for flight attitude testing and flight positioning precision testing of the unmanned aerial vehicle can be shortened;and, moreover, attitude parameters used for testing the flight attitude of the unmanned aerial vehicle are collected in the flight process of the unmanned aerial vehicle and are corrected by the processor, so that the measurement deviation caused by the installation deviation of the attitude acquisition module is overcome, and the test result has higher accuracy. The invention further discloses amethod for calibrating the attitude acquisition module in the unmanned aerial vehicle flight parameter acquisition equipment.

Disclosed are an oxygen concentration measurement method and system based on paramagnetic properties of oxygen molecules, The system includes a measurement gas path, a reference gas path, a measurement gas chamber, a pressure difference sensor, and an electromagnetic component used for providing a changing magnetic field. The changing magnetic field acts on the measurement chamber. The measurementgas chamber communicates with the measurement gas path and the reference gas path. Two pressure sensing ends of the pressure difference sensor communicate with the measurement gas path and the reference gas path to measure a gas path difference between the two gas paths. Due to the paramagnetic properties of oxygen, under the action of the changing magnetic yield on the measurement gas chamber, the gas path difference is generated between the two ends of the pressure difference sensor. A gas path pressure difference signal contains oxygen concentration information of measured gas, is modulated on a wave carrier frequency of an excitation current signal frequency of the electromagnetic element, is amplified by an analog circuit, and then is demodulated and analog-to-converted to obtain a digital oxygen concentration signal. The oxygen concentration measurement method and system designed by the invention have the advantages of good anti-vibration performance, low power consumption, zerodrift resistance, accurate measurement and good robustness.

The invention provides a distributed grating temperature measurement method based on a two-time data fusion technology. The method comprises the following steps of: by using a fiber Bragg grating as a temperature measurement element, measuring a temperature value by detecting a reflection signal of the grating; performing analog-to-digital conversion on the measured temperature value, and sampling; performing first-time tail-cutting weighting data fusion on multi-channel data which is sampled by using a microprocessor, and estimating the influence of interference factors such as cross sensitivity on the measuring accuracy of the grating; replacing the maximum value and the minimum value in the original data by using a tail-cutting weighting data fusion result, and thus obtaining a group of new data; and performing second-time fusion weighting minimum mean square error fusion on the new data, and thus obtaining a fusion result which serves as a final output result. The method is simple in implementation; and by adoption of the method, the problems of difficulty in elimination of the cross sensitivity and low measurement accuracy in the conventional grating measurement are solved, and the robustness of a measurement system is improved.

The invention discloses a device and a method for measuring the charge generated by single-particle sliding friction. The method comprises the following steps: a base, a bracket, a knob and a supportplate are used to set up a sloping slide way; a general Faraday cup and a Faraday cup are connected with an electrometer; the guide section of the slide way measures the initial electrostatic charge of a sample particle through the general Faraday cup; the Faraday cup is placed below the end of the effective friction section of the slide way to measure the final electrostatic charge of the particle; and the amount of electrostatic charge generated by sliding friction between the sample particle and the slide way is accurately calculated by subtracting the initial electrostatic charge from thefinal electrostatic charge. The general Faraday cup and the Faraday cup are combined for the first time in the measurement of charge generated by single-particle friction. The general Faraday cup andthe Faraday cup can simultaneously measure the initial electrostatic charge and the final electrostatic charge. The measurement precision of charge generated by friction is improved. The device and the method are suitable for precisely analyzing the charge generated by friction between particles and the wall.

The invention provides a method for testing a wet expansion coefficient of a composite material under a dehumidification condition. The method comprises the following steps of: starting a measurementand control program, and adjusting the humidity in a vacuum tank to saturated humidity; under the environment of normal pressure, normal temperature and saturated humidity, placing a pretreated samplein the vacuum tank, recording, by a displacement sensor, the initial length of the sample, and recording, by a load sensor, the initial weight of the sample; starting a measuring and recording program, sealing the vacuum tank, carrying out vacuumizing, and dehumidifying and drying the sample in the vacuum way; collecting humidity, temperature and air pressure data in the vacuum tank, and recording the weight and length change of the sample; and adjusting the pressure in the vacuum tank to be normal pressure, and stopping the measurement and control program. According to the testing method provided by the invention, a dehumidification process of the sample is carried out before testing, and vacuum dehumidification is adopted in the testing process, so that measuring time is effectively shortened, and a measuring deviation caused by inherent time drift of an electric measuring instrument is also avoided.

The invention relates to a controller reference power supply fault diagnosis and correction method based on compressed sensing, and the method comprises the following steps: carrying out the system analysis of an internal reference power supply circuit of an aero-engine controller, building a correlation model, and obtaining a correlation graphical representation model and a mathematical model matrix; establishing a linearized fault equation according to the correlation model; based on an orthogonal matching pursuit algorithm, a fault mode is obtained through reconstruction of the measured value and the fault feature matrix, and fault diagnosis of the reference power supply is achieved; and by calculating the projection lengths of the measured values in different fault subspaces, the offset proportions of all the parts are evaluated, so that reference power supply correction is realized, and the measured values are corrected. According to the invention, the fault detection rate of the system is improved, the test point demand can be reduced, the positioning of a single-point fault and a multi-point combined fault can be realized at the same time, an effective means is provided for the health management of the system, a reference power supply deviation correction method is provided, and the measurement precision of the controller is improved.

The invention relates to a strip type surrounding rock pressure monitoring device, a monitoring method and a mounting method. The monitoring device covers the full-section range of a tunnel in the circumferential direction and comprises an upper protection layer, a lower protection layer and a pressure sensor, and the pressure sensor is packaged between the upper protection layer and the lower protection layer; and the pressure sensor comprises a plurality of pressure-sensitive units which are distributed in a strip shape, each pressure-sensitive unit comprises a plurality of pressure-sensitive elements, and each pressure-sensitive element comprises a plurality of film-type piezoresistors. Compared with the prior art, measurement deviation caused by surrounding rock joints can be effectively avoided, the surrounding rock pressure of any position in the middle can be accurately calculated, and the purpose of sensing the surrounding rock pressure in a full-section distributed and refined mode is achieved.

The invention discloses a method for testing the thermal shrinkage rate of a battery diaphragm. According to the method, an image pickup device is adopted; the area change of the diaphragm at different temperatures is tested directly, so that the thermal shrinkage rate of the diaphragm is obtained. Equipment used in the method is simple; operation is convenient; and test precision is high. A wholetesting process can be continuously and automatically carried out, so that human influence factors are reduced; the area of the diaphragm is obtained through an image processing method. The thermal shrinkage rate of a diaphragm in any shape can be tested. The thermal shrinkage rate of the diaphragm at the different temperatures and the image information of the diaphragm at the different temperatures can be obtained more accurately.

The invention discloses a precision-loaded RV reducer performance detection device and method, including a test bench and a measurement and control system; wherein, the test bench includes a bench, a tested RV reducer bracket, a power end sliding platform, and a power end sliding platform track , load-side sliding platform, load-side sliding platform track, power motor, load motor, tested RV reducer, accompanying test RV reducer and other components; the measurement and control system includes hardware and software parts, and the hardware part mainly includes industrial computers and sports cards. , Data acquisition card, input torque speed sensor, output torque speed sensor, input grating, output grating, vibration acceleration sensor, etc. The software part mainly includes speed fuzzy PID control program, torque fuzzy PID control program, torque speed fuzzy PID control program, etc. The invention ensures high coaxiality when the components are installed, thereby effectively improving the stability and reliability of the performance detection of the RV reducer.

The invention relates to a disposable central venous pressure measuring device. The disposable central venous pressure measuring device comprises an intravenous infusion needle, a three-way valve and a closed container, wherein the intravenous infusion needle comprises a needle head, a needle tube cavity and an infusion catheter which are successively connected; the three-way valve is connected to one end of the infusion catheter; the closed container is connected to the other end of the three-way valve; the closed container comprises a normal saline region and a measurement region; the normal saline region is connected with the measurement region through a partition board; and a spring is fixedly arranged in the measurement region. The invention further provides an application method of the disposable central venous pressure measuring device. Compared with a conventional product, the disposable central venous pressure measuring device provided by the invention has the advantages that an original two-person operation mode is converted into a one-person operation mode, so that manpower is reduced; moreover, the operation is simplified,the operation time of medical personnel is greatly shortened, and the working efficiency is improved.

The invention discloses a device and method for measuring static electricity generation by the impact of particles. An oblique sliding rail is arranged by using a pedestal, a bracket, a clamp and a circular tube sliding rail. A general Faraday cup, a Faraday cup, and an electrometer are connected. A sliding particle passes the general Faraday cup through the sliding rail and thus an electric charge of the sliding particle before an impact is measured; the sliding particle leaves the sliding rail, impacts on a suspension particle, and then falls into the Faraday cup to measure an electric charge of the sliding particle after the impact. The electric charge before the impact is subtracted from the electric charge after the impact, so that the electrostatic charge generated after the impact of the two particles is calculated accurately. According to the invention, the electrostatic charge generated after the impact on the suspension particle can be measured and mutual verification with the electrostatic charge amount generated after impact with the sliding particle is realized.

The aim of the invention is to provide an accurate measurement method for escaping ammonia after an SCR device in a thermal power plant, which is used for solving the technical problem of accurate measurement for escaping ammonia. The accurate measurement method for escaping ammonia after an SCR device in a thermal power plant includes the steps: selecting a rectangular flue cross section as a measurement plane between an SCR device outlet and an air preheater inlet, and equally dividing the flue cross section into m*n measuring points; measuring ammonia gas concentration of each point; and correcting flue gas velocity vij, and then performing arithmetic average calculation on the actual value of NH3tp at each sampling time in a sampling period, to obtain the actual escaped ammonia value NH3AV in the measurement period. The invention has the advantages of simple measurement method and more accurate measurement result.