Abstract:

Abstract:The decoupling in the fiber Bragg grating flow and temperature composite sensing is a difficult problem. To address this issue, a fiber Bragg grating flow and temperature composite sensor based on particle swarm decoupling algorithm is proposed. Firstly, combining the fiber Bragg grating sensing theory and the flow and temperature composite sensing theory, the flow and temperature composite sensing mechanism based on the fiber Bragg grating is studied. Then, a fiber Bragg grating flow and temperature composite sensor that integrate target structure with the cantilever beam of hollow cylinder is designed, a flow and temperature experiment system platform is established. The temperature and flow composite sensing experiments are carried out. Finally, a FBG flow and temperature composite sensor decoupling method based on the particle swarm algorithm is proposed. The proposed particle swarm optimization algorithm is used to decouple the experimental data from the flow and temperature. Research results after decoupling show that the maximum flow error of the sensor in the range of 3~ 8 m 3 / h is 0. 014 m 3 / h, the maximum temperature error is 0. 021℃ , the flow measurement error is 0. 28% , the temperature measurement error is 1. 5% , the flow mean-square error is 1. 16×10 -4 m 3 / h, and the temperature mean-square error is 1. 53 × 10 -4℃ . Compared with the neural network algorithm, results show that the particle swarm optimization algorithm has a good decoupling effectiveness. The measurement accuracy of the sensor could be improved effectively.

Abstract:In order to meet the current demand for liquid flow velocity measurement in miniaturized equipment, a new method suitable for measuring fluid velocity in non-full tube is proposed by combining spatial filtering velocity measurement with capacitively coupled contactless conductivity detection ( C 4D) technology. A C 4D sensor with an axial two-electrode structure is designed. The threedimensional simulation model of the sensor is established using COMSOL simulation software, and the spatial sensitivity distribution characteristics of the sensor is analyzed. The principle of liquid velocity measurement is theoretically deduced based on the spatial filtering effect of the sensor, and the mathematical expression of velocity measurement is obtained using the method of equivalent peak frequency. On this basis, a set of C 4D liquid flow velocity measurement system that is suitable for spatial filtering was designed, and the good spatial filtering effect of C 4D sensor was verified with this measurement system. The experiment results show that the measurement method has good feasibility. In the velocity range of 1. 39~ 2. 35 m/ s, the absolute error of measured velocity is within 5% .

Abstract:The orifice flowmeter is a kind of flow measurement element which is commonly used in the field of environmental monitoring. According to the difference of upstream inlet pressure of calibrated orifice flowmeter, calibration methods of the orifice flowmeter can be categorized into two kinds of calibration conditions, which are micro positive pressure and micro negative pressure. However, both working conditions are recommended by national standards and specifications, and the deviation of the two calibration conditions is up to 10% . The calibration deviation of the two working conditions is caused by additional differential pressure value introduced by clamping device used in positive pressure condition and linearity error introduced by the lack of available expansibility factor formula. The forms and structural parameters of clamping device which is insensitive to the upstream pressure of the calibrated orifice flowmeter are designed by the computational fluid dynamics simulation method. An available expansibility factor formula for the orifice flowmeter is calculated based on the simulation data. The achieved formula is used to carry out evaluation. The deviation of flow coefficient between the micro positive pressure and micro negative pressure calibration is less than ±0. 5% . The flow coefficient linearity of the orifice flowmeter within the calibrated flow range is also improved by about 0. 1% .

Abstract:Taking TRZ80 gas turbine flowmeter as the research object, the structural optimization scheme of the front rectifier and the rear deflector is proposed by combining numerical simulation and experimental test. Through the analysis of the internal flow field characteristics before and after structural optimization, the exact hydrodynamic mechanism behind the structure and performance optimization of flowmeter is revealed. Research results show that the sudden change of pressure drop in the front rectifier and rear deflector area, as well as the vortex structure and reflux phenomenon at the rear deflector tail, are the main mechanisms that affect the metering performance of the flowmeter. The optimized structure can greatly reduce the sudden change of pressure drop, vortex structure and reflux phenomenon. In addition, the optimized structure can significantly reduce the pressure loss of the flowmeter. And it can also obviously improve the measurement accuracy and stability of the flowmeter. The pressure loss and linearity error are reduced by about 48. 58% and 32. 43% , respectively. Research results could help to provide theoretical guidance and technical support for the development and mass production of gas turbine flowmeter with better metering performance in the future.

Abstract:There is the nonlinear phenomenon in the output signal of double-tube Coriolis mass flowmeter, which is mainly the frequency doubling signal. The source has been traced from the perspective of numerical analysis. In this article, the full parametric model built by ANSYS finite element analysis software is used to further evaluate the reliability of the numerical model through simulation experiments. By analyzing the influence of the excitation force on the nonlinear vibration of the measuring tube mass and the thickness of the measuring tube spacing plate, it proves that the measuring tube stiffness and the constraint stiffness have important effects on suppressing the nonlinear vibration. Then, the additional mass method is used to improve the local stiffness of the coupling system to suppress the nonlinear frequency doubling phenomenon. Results show that the improved local stiffness can effectively suppress and eliminate the nonlinear phenomenon. The nonlinear suppression experiments are carried out, and the results accord with the simulation analysis, which verifies the correctness of the theoretical research. This part of work provides theoretical support and technical guidance for further refining nonlinear suppression scheme and carrying out nonlinear suppression experiments. Combined with the specific measurement environment and measurement requirements, the nonlinear phenomenon can be suppressed or eliminated, as the next step of CMF optimization design basis.

Abstract:By combining experimental and numerical simulation methods, the structural optimization of the rear deflector for LWQ80 gas turbine flowmeter and the variation law of its metering performance is studied in this article. Based on the investigation of the internal flow field characteristics and flow mechanism of turbine flowmeter, it is found that the separation of boundary layer and the deflection of flow direction are two main causes which influence the pressure loss of the rear deflector. Based on this, the optimization idea of reducing the separation area and improving the diversion effect of the deflector is proposed. An improved structure of rear deflector is designed by extending the length of the rear deflector and posting the position of the deflector. Results show that it is equipped with the selected deflector that the comprehensive performance of the flowmeter is obviously improved. At the detection point of 250 m 3 / h, the pressure loss is reduced by 20. 5% , the constancy of the instrument coefficient is significantly improved, the maximum indication error is reduced by nearly 2. 5 times, and the service life of the flowmeter can be effectively prolonged. Research results are helpful to provide theoretical guidance and technical support for the structure and performance optimization of the gas turbine flowmeter.

Abstract:The collection and control of micro-fluid are key technologies in the field of microfluidics. The introduction control of microfluid requires not only the precise control of velocity, time and other parameters, but also the avoidance of cross contamination of fluids in multiple detection areas. In this article, a microfluidic liquid-introduction-control chip based on the bursting valves is designed. Firstly, the mechanism of the bursting valve is analyzed and the microfluidic chip is fabricated by the MEMS process. Then, the hydrophilicity of PDMS that affects the characteristics of the bursting valves is tracked. The liquid introduction characteristics of the microfluidic chip are observed at both macro and micro levels. Furthermore, the theoretical calculation and experimental measurement of the bursting pressure of the bursting valves are carried out, and the measured bursting pressure values of the three types of bursting valves are 90, 690 and 2 440 Pa, respectively. Finally, the blasting characteristics of the bursting valves under different injection rates are tested. Experimental results show that, through the reasonable design of the bursting valves, the introduction control of micro-fluid can be effectively controlled. The liquid can flow into the detection area in a predetermined order and time, and the cross contamination of fluids can be avoided effectively.

Abstract:The on-line accurate measurement of high temperature liquid metal flow is of great significance for the safe operation of equipment, industrial process control, optimization of measurement, calibration equipment, etc. According to whether there are obstacles in the measuring instrument structure, this article classifies and analyzes the existing technologies. The advantages and application limitations of the existing measurement technologies are discussed from the principle of measurement technology, application environment, and characteristics. To ensure the accuracy and reliability of the measurement, the online calibration of instruments and meters for high-temperature liquid metal flow measurement is one of the key technologies. This article analyzes the existing technologies. At present, there are few high-temperature liquid metal flow measuring instruments that can work continuously for a long time in the environment above 600℃ , and the online calibration error is 6% ( or more). On the basis of summarizing the existing measurement technologies, the future development direction of the online measurement and the calibration technology of high-temperature liquid metal is prospected. It aims to provide a certain reference for the detection of flow parameters in the nuclear industry and other special industrial production and control process.

Abstract:Aiming at the problem of lacking of effective cutting particle diameter prediction method in the cut cyclone design process, two key indexes affecting the change of cutting particle diameter are proposed in this paper. The flow field characteristics of the cut cyclone under 30 L/ min volume flowrate are studied with CFD method, through analyzing the performance changes of the cutting efficiency, median particle diameter, pressure drop and etc. caused by the structural dimensions of cylinder and cone sections, considering the two key indexes of the centrifugal effect ψ and structural height to cyclone length ratio Y/ l, the changing law of the structural dimensions affecting the cutting particle diameter is obtained, and the results agree with the experiment trend in the reference article. The study shows that when Y/ l≤70% , increasing Y/ l can improve the cutting performance; increasing the ratio of conical section to total height can improve the cutting performance while reducing the structural resistance; increasing the inner surface area of the cut cyclone can reduce the structural resistance. Starting from studying the changes of the two key indexes, this paper provides a reference for the cut cyclone structure design and the precision control of cutting particle diameter.

Abstract:Aiming at measuring the total temperature of high-speed airflow of the aero-engine, a novel total temperature probe combined with the stagnation tube and fiber grating is proposed. Due to its small size and single-end sensing structure, the fiber grating is a competitive alternative for temperature sensing. A numerical simulation method is employed to design the aerodynamic structure of probe and analyze the influence of the structure parameters on the measurement results. Based on this, the fiber grating total temperature probe is fabricated, and the total temperature measurement system is established. And the working performance of the probe is tested under the subsonic wind tunnel. Results show that the probe has good stagnation effectiveness and stability with Mach numbers between 0. 3 and 0. 8. When the Mach number is larger than 0. 5, the recovery factor is above 0. 8. It is as high as 0. 99 when the Mach number is 0. 8. The diameter of the miniature fiber grating total temperature probe is 0. 8 mm, and the overall size is much smaller than that of a thermocouple probe. It can effectively reduce the interference to the flow field while satisfying the precise measurement of the total temperature.

Abstract:During the construction robot indoor operation, how to realize the accurate solution of the odometer has vital influence on the subsequent positioning and mapping and precise operation. The traditional simultaneous localization and map building (SLAM) method has the accuracy problem due to loopback detection. To address this issue, a method using building information modeling (BIM) data to correct the cumulative error of laser odometer is proposed to achieve precise positioning. Firstly, the global initial positioning of the robot in the BIM is solved at the initial moment. Secondly, the key points of the 3D point cloud are extracted and converted into 2D data. Then, the data of the wheel odometer are set as the predicted value to solve the inter-frame transformation. Finally, the BIM data are combined to eliminate the cumulative errors and obtain a high-precision odometer positioning. Experimental results show that this method has good stability and accuracy in robot initial positioning, laser point cloud processing and motion solution for eliminating accumulative errors. The initial positioning error is less than 2 mm, and the odometer offset error is controlled within 0. 09% , which provides a strong guarantee for the accurate establishment of the subsequent point cloud map.

Abstract:With more and more extensive application of spatial geometric precision measurement technology in the manufacturing and assembly process of equipment manufacturing industry, angle measurement is developing from plane angle to spatial angle. The spatial angle of the different planes of the magneto-optical trap is measured. A parallel flat crystal is utilized as the standard plane to draw the normal vector of the surface to be measured. The spatial angle is effectively divided into two plane angles, which are the horizontal projection angle and the vertical projection angle. The traceability of the spatial angle is guaranteed, and the maximum spatial angle deviation between the normal vectors of the measured surfaces of the magneto-optical trap is 0. 286 0 mrad. Then, the measurement uncertainty of this method is evaluated as 0. 095 9 mrad by the Monte Carlo method. Compared with the coordinate measuring machine method, the maximum deviation is 0. 184 2 mrad. When the flatness index of the surface is set to ± 0. 145 4 mrad, the consistency between the two is good. At present, this method has been applied in the development of the physical vacuum subsystem of the NIM5 cesium atomic fountain clock, which proves that the method can meet the accuracy requirements of the measurement.

Abstract:Magnetostrictive transducers have high core eddy current loss, uneven magnetic field distribution and low electromagnetic conversion efficiency under high frequency excitation. These issues need to be addressed by the optimal design of the transducer body. The coil height and yoke loop structure of the transducer are firstly simulated to initially determine the magnetic circuit structure. Then, an overall multi-objective optimization design model for the transducer is proposed, which is based on the non-dominated ranking genetic algorithm. The optimization objectives are to increase the magnetic field strength in the magnetostrictive bar, improve the uniformity of the magnetic field distribution in the bar, and reduce the high frequency loss of the transducer. The normalized ranking and entropy weighting methods are introduced for decision support of the Pareto front solutions obtained by this optimization method to screen a set of optimal design solutions. Finally, the optimal solution is simulated and analyzed. Results of magnetic field distribution and numerical calculation verify the effectiveness of the optimization method.

Abstract:The wave-driven ocean profile observation platform has the comprehensive advantages of independent lifting, fast profile, high temporal-spatial resolution and long-term continuity. It is of great significance to the study for the fast changing processes of smallsubmesoscale dynamic process, phytoplankton physiological diurnal change and biogechemical cycle in the ocean. In this article, a wave powered profiler prototype is independently designed and developed. The test is implemented in Jiaozhou Bay, Qingdao for 23 days from August 8 to August 31, 2021. A total number of 2 367 profiles are obtained, which are probably 102 profiles per day with an average profile cycle of 8. 19 minutes. The results further show that the system is greatly affected by tidal current under the calm sea state at about level 1. However, in the relatively high sea condition above level 2, the prototype could nearly work continuously throughout the day. The sea test has preliminarily proved that the prototype of the developed wave powered profiler has a good working sensitivity, state stability and mechanical endurance. The cost is only about 20% of the price of similar foreign products. The success of the prototype is a key step to achieve the goal of localization of the new profile platform.

Abstract:It is difficult to implement high-precision measurement and evaluation of the full surface topography of inertial confinement fusion (ICF) capsule. In this article, an optimized sphericity measurement method is proposed, which is for the latitude and longitude traces based on the principle of laser differential confocal. Firstly, the method uses the measurement system to achieve precise focusing of the circumferential sampling points on the capsule surface. Secondly, the measured cross section of the capsule is switched by using the precise 3D adjustment mechanism and an orthogonal rotary system. The height information at the latitude and longitude traces of the whole capsule spherical surface is obtained. Finally, the 3D coordinate transformation model of complete coverage mode is formulated. The least square algorithm is used to evaluate the sphericity of the capsule, and the 3D surface of the capsule is reconstructed. The experimental results show that the sphericity error of the measured capsule is 1. 946 μm when 57 traces are measured. This method provides a feasible scheme for the high-precision measurement and evaluation, qualitative observation of the full topography of the ICF capsule surface.

Abstract:Magnetic particle imaging (MPI) belongs to the non-invasive imaging technology, which can characterize the concentration distribution of magnetic particle by detecting the magnetization signal of magnetic particle tracer. When it is utilized to detect the magnetization signal of magnetic nanoparticles, how to remove the excitation signal from the induced voltage is a key problem to be solved. The method for removing the excitation magnetic field feed-through in magnetic nanoparticles imaging signal detection is studied. The planar gradient detection coil is designed, and an iterative compensation control method is proposed to eliminate the excitation magnetic field coupling. In this way, the magnetization signal detection of magnetic nanoparticles is realized. Simulation computing and experimental results show that particle signal detection for different detection models can be realized by the proposed detection method. The signal-to-noise ratio of the particle signal obtained by this method is 2. 2 times that of the original detection method and 1. 3 times that of the filtering method. The excitation magnetic field feed-through suppression is up to 34 dB.

Abstract:Temperature test is extremely important for the design and development of the aero-engine. The working environment of the aero-engine has the characteristics of high temperature, high pressure, high-speed airflow, high-speed rotating, and narrow space. It also requires the measurement system to have the performance of large range, high precision and high stability. At present, the available methods are very limited. The optical fiber temperature sensor has advantages of small size, anti-electromagnetic interference, safety and reliability in extreme environment, which is flexible to be utilized. It has the quasi-distributed sensing capability of series multiplexing, which has a good application prospect in the temperature test of the aeroengine. This article compares and summarizes the sensing principles, manufacturing processes and technical characteristics of several optical fiber temperature sensors, such as fiber Bragg grating, Fabry-Perot, fiber ultrasonic and fiber radiation. Temperature test requirements in different conditions of the aero-engine are analyzed. The application research progress of the optical fiber temperature sensing technology is classified and summarized. The deficiencies and future development directions of optical fiber sensing technology in the application of temperature measurement are analyzed and prospected to provide reference for follow-up research.

Abstract:As a major gas pollution source in our country, the NOx poses a serious threat to the natural environment and human health. Therefore, it is necessary to develop high-efficiency detection equipment for the in-situ detection of NOx . The emission sources of NOx are mainly industrial exhaust gas and automobile exhaust gas. The gas temperature is relatively high and the composition is relatively complicated. The solid electrolyte-based gas sensor can realize high selectivity and high sensitivity detection of NOx at high temperature. In this study, a Co3O4 / Cr2O3 / YSZ composite material is used as the sensing electrode and YSZ is used as the solid electrolyte to prepare the impedance metric NOx sensor. The sensor is characterized by XRD, SEM and EDX, and the NOx sensing performance at high temperature is systematically studied. Results show that the Co3O4 / Cr2O3 / YSZ sensing electrode with about 200 nm particle size has a high specific surface area due to the loose and porous structure, which is conducive to gas diffusion and mass transfer. The sensor shows a good response-recovery characteristic to NOx, and the O2 concentration has little influence on the sensor. In addition, the sensor shows good reproducibility, stability, and selectivity. To further apply the sensor for the in-situ detection of NOx under high temperature, a novel self-heated sensor is proposed. The sensor shows good sensitivity characteristics, and the concentration detection range is 10×10 -6 ~ 1 500×10 -6 . In addition, the self-heating sensor shows good reproducibility. This study provides a new idea for the in-situ detection of NOx gas at high temperature.

Abstract:In this article, a magnetic-focusing optical fiber current sensor based on the step-type magnetostrictive composite material is proposed, which solves the distribution problem of the current-induced magnetic field high at both ends and low in the middle on the conventional magnetostrictive composite material. Firstly, the magnetic field distribution model of the sensor is formulated by using the Ampere loop law. The theoretical analysis shows that the central magnetic field of the material is inversely proportional to the thickness of the material l 1 , the height of the bridge deck l 2 and the length of the bridge deck h1 . Secondly, the finite element simulation analysis is implemented for the key parameters of the sensor. Simulation results show that the material thickness l 1 , the bridge deck height l 2 and the bridge deck length h1 are the main influencing factors of the magnetic field in the center of the material. The magnetic field decreases with the increasing of the material thickness l 1 , the bridge deck height l 2 and the bridge deck length h1 , which is consistent with the theoretical analysis. Finally, the material is prepared and the performance test is carried out. Results show that with the increasing of current, the strain at the middle and both ends of the material increases gradually. The linear working range of the sensor is 0~ 1 000 A, and the sensitivity is 0. 136 με / A.

Abstract:The high voltage driving and intrinsic safety cannot be combined when the ultrasonic transducer is used to monitor the drilling condition of kilometer directional drilling machines. To address this issue, an intrinsically safe ultrasonic transmitting circuit based on energy storage inductance is proposed. The basic principle of the transmitting circuit is introduced, and the effects of the equivalent impedance of the transducer and the dynamic resistance of the regulator on the discharge time and exciting pulse width of the energy storage inductance are studied theoretically. The internal and output intrinsic safety characteristics of transmitting circuit are analyzed. Then, a judgment standard of intrinsic safety parameters and a parameter calculation method of high voltage intrinsically safe ultrasonic transmitting circuit are illustrated. Experimental results show that the exciting pulse width of 200 V amplitude can reach 2 ~ 3 μs in the range of design parameters, which is greater than the design value of 1. 5 μs. The measured energy storage inductance current is 0. 9 A and the equivalent capacitance of the transducer is 1. 05 μF. The current is smaller than 1 A and capacitance is smaller than 100 μF under intrinsically safe condition. Therefore, the circuit parameters obtained by the proposed method can meet the intrinsic safety requirements under the output of high voltage exciting pulse.

Abstract:The baseline of the fiber Bragg grating (FBG) sensor network spectrum signal drifts, which is caused by the environmental conditions. To address this issue, this study proposes a spectrum baseline correction method based on the improved empirical mode decomposition (EMD). When this method is used to process simulation data, the spectrum after processing can be divided into the reflection peak regions of each FBG by setting the threshold value. The feasibility of the improved EMD method is verified. The spectral signals of the FBG sensor network with baseline drift under the influence of optical fiber path loss and end reflection are collected by experiments. The improved EMD method, the wavelet soft threshold method and the penalty least square method are used to achieve the real-time correction of the spectrum. The Gaussian nonlinear fitting method calculates the center wavelength of each FBG of the normal and corrected spectra. Results show that the survival rates of the sensing signal are increased by 48. 9% and 61. 6% , with the average deviation and deviation of each FBG center wavelength calculated after the use of the improved EMD method. The standard deviation values are the smallest, which are 4. 33, 6. 28 and 6. 01, 6. 58 pm. The spectral signal corrected by this method could provide reliable information for physical quantity detection.

Abstract:In semiconductor, printed circuit board (PCB), automobile assembly, liquid crystal display (LCD), 3C, photovoltaic cell, and textile industries, the appearance of the product is closely related to the performance of the product. Surface defect detection is an important way to prevent defective products from entering the market. The utilization of machine vision technology to perform inspections with high efficiency and low cost is the main direction of future development. This article reviews the research progress of surface defect detection methods based on machine vision in recent ten years. Firstly, the definition of defect is given, and the general steps of defect detection are described. Then, it focuses on the principle of defect detection using traditional image processing methods, machine learning, and deep learning. The advantages and disadvantages are compared and analyzed. The traditional image processing methods are divided into segmentation and feature extraction. Machine learning consists of unsupervised learning and supervised learning. Deep learning mainly covers most of the mainstream networks for detection, segmentation and classification. Then, 30 kinds of industrial defect data sets and performance evaluation indexes are introduced. Finally, the existing problems of defect detection methods are pointed out and the further work is prospected.

Abstract:Ultrasonic internal inspection is one of the main defect detection methods for the oil and gas pipeline. At present, the location of the defect boundary is inaccurate in the case of small industrial samples for ultrasonic internal inspection. This article proposes a small sample defect recognition method based on multi-dimensional selective search. Firstly, ultrasonic echo features are extracted by two steps, which are feature point extraction based on isolated forest and feature point clustering based on the natural breaks classification method. Secondly, the risk similarity measurement method is proposed. A regression model of waveform characteristics and risk degree is formulated by the boosting tree. Thirdly, multi-dimensional defect similarity is integrated information into a selective search algorithm to realize small sample defect identification. Finally, regional risk metrics such as anomaly scores are used to achieve precise positioning of defect boundaries. Experimental results show that the recall and precision of the small sample defect recognition method based on multidimensional selective search are 95. 08% and 85. 46% , which can effectively solve the problem of inaccurate positioning of the ultrasonic signal defect boundary detection.

Abstract:At present, the decommissioned power batteries have problems of low screening efficiency, high energy consumption and low grouping rate. To address these issues, a fast screening and recombinant method is proposed, which is based on short-time pulse discharge and electrochemical impedance spectroscopy ( EIS ) for decommissioned power batteries. Through the short-time pulse discharge, EIS test and analysis of 200 decommissioned lithium iron phosphate power batteries of the same type and different batches, the obtained pulse voltage difference, DC internal resistance, EIS curve shape characteristics and EIS equivalent circuit model parameters are taken as screening indicators. Then, a mathematical model is formulated to realize the rapid and effective sorting and reorganization of decommissioned power batteries. Experimental results show that this method can effectively reduce energy consumption. The average test time of a single cell is less than 20 min. Meanwhile, the module consistency index after grouping is good, which has great practical value in engineering.

Abstract:To solve the problem of multi-phase measurement in oil production, a high-precision and high-sensitivity detection instrument for multi-parameter measurement of petroleum production is designed and developed, which is based on the innovative fiber-conductance combined probe developed by the research group. The ZEMAX ray tracing method and the FEM numerical analysis method are both used to theoretically analyze the electric field distribution and response characteristics of the fiber-conductance combined probe array multiphase logging tool. It has been verified that a good measurement effect can be realized under working conditions such as flow rate of 5, 10, 20, 30 m 3 / d, gas holdup of 10% , 20% , 30% , 40% , and water holdup of 90% , 80% , 70% , 60% , etc. To further prove its excellent performance, the multiphase flow conditions are considered, such as liquid flow rate 30 m 3 / d, the liquid phase water holdup 25% , 45% , 65% and 85% , and the gas flow rate 6, 12, 24 m 3 / d, etc. The dynamic experimental analysis is carried out. The measurement error of FCCPA_MLT gas holdup is within 5% , and the water holdup error is within 10% . The actual dynamic experiment and the simulation results remain the same. Results show that the developed fiber-conductance combined probe array multi-phase logging tool has good performance.

Abstract:The diagnosis and treatment effect of the swallowing wireless magnetic capsule robot in gastrointestinal tract is closely related to the external magnetic driving force of the robot. In this article, the theoretical model of external magnetic driving force is formulated. The mathematical expression of the interaction between two diametrical magnetizing ring permanent magnets is deduced which is based on the equivalent magnetic charge method. The numerical calculation is carried out by the adaptive recursive calculation method. In addition, a real-time measurement method of magnetic force between ring permanent magnets is developed, a magnetic-spacing synchronous measurement instrument is developed to carry out experimental research, and a finite element simulation model of 3D ring permanent magnets is formulated. The experimental measurement of the magnetic-spacing relationship is in good agreement with the theoretical calculation and finite element simulation results. The error is less than 4% , which verifies the accuracy and reliability of the theoretical model and the finite element simulation model. The influence of length, thickness and volume of embedded permanent magnet in the capsule robot on magnetic force is revealed by parameter analysis. The results provide a theoretical foundation for precise driving of capsule robot in gastrointestinal tract.

Abstract:Pipeline magnetic flux leakage internal detection technology is internationally recognized as the most effective method for safety maintenance of long-distance oil and gas pipelines. To solve the problem of quantifying the internal detection signal of magnetic flux leakage in long-distance oil and gas pipelines under load, an improved three-dimensional magnetic charge mathematical model is formulated, which is based on the J-A theory. The influence of the magnetomechanical influence of pipeline defects on the magnetic flux leakage signal under internal pressure is analyzed. The influence law of the defect size on the magnetic flux leakage signal under the action of external load is studied, and the correctness of the theoretical model is evaluated through systematic experiments. Research results show that the internal pressure of the pipeline increases, the magnetization of the material decreases, and the radial and axial components of the magnetic flux leakage signal decrease exponentially. The peak value of the radial component and the maximum axial component of the magnetic flux leakage signal increase with the depth of the defect. The growth rate gradually decreases, and the eigenvalue changes by 6. 5% and 14. 7% , respectively. The peak growth rate of the radial component gradually decreases with the increase in length, and the axial maximum value decreases linearly. The eigenvalue changes by 21. 0% and 36. 8% , respectively. The axial component is more sensitive to changes in defect depth and length.

Abstract:The aggravation of left ventricular diastolic dysfunction (LVDD) could lead to left ventricular remodeling, wall stiffness, and the reduced compliance, which make progression to heart failure with preserved ejection fraction (HFpEF). To achieve early diagnosis of LVDD, a non-invasive method is proposed, which utilizes the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) multi-scale sample entropy (MSE) characteristics and the logistic regression model. Firstly, the improved wavelet denoising method is used for heart sound signals preprocessing. Then, the non-stationary heart sound signals are decomposed into several intrinsic mode functions ( IMF) which reflect the characteristics of heart sound itself by the ICEEMDAN method. The mutual correlation coefficient criterion is used to select IMF. The MSE values of the selected IMFs are extracted to form the eigenvectors, which are used as the input into the classifier for identification. Finally, the logistic regression is applied for LVDD identification by the comparison of performances with other three models. Results show that the proposed method could effectively extract the features of heart sound with 89. 85% accuracy, 92. 17% sensitivity and 87. 63% specificity, which demonstrate the effectiveness of heart sound signals for LVDD diagnosis.

Abstract:Magnetic components are important parts of power converters. The accurate core loss measurement is very important for the optimization of magnetic components. To improve the measurement accuracy of the traditional dual-winding AC power method for core loss measurement with high-frequency excitation, the measurement principle and error source of the inductor voltage compensation AC power method are analyzed in detail. Based on the error problem that the core loss of magnetic components with high impedance angle is measured with the inductor voltage compensated AC power method under incomplete compensation, the inductor voltage partially compensated AC power method is proposed to accurately measure the core loss under arbitrary waveform excitation in this article. Finally, the measurement platform is established under the condition of incomplete compensation. The maximum relative error of this method for core loss measurement of the powder core with 50 kHz sine wave excitation is 13. 54% , and the maximum relative error of core loss measurement of the powder core with 50 kHz rectangular wave excitation is 9. 8% . Experimental results show that the core loss of magnetic powder core under sine wave and square wave excitation can be accurately measured by the proposed method.