The accuracy of power system measurements directly affects the safe and stable operation of power grids. This study explores the application prospects of quantum sensing technology in power system measurements. The re...The accuracy of power system measurements directly affects the safe and stable operation of power grids. This study explores the application prospects of quantum sensing technology in power system measurements. The research first analyzes the limitations of traditional measurement techniques, such as electromagnetic interference sensitivity and measurement accuracy bottlenecks. It then introduces the basic principles of quantum sensing, including concepts like quantum entanglement and superposition states. Through theoretical analysis and numerical simulations, the study assesses the potential advantages of quantum sensors in current, voltage, and magnetic field measurements. Results show that quantum magnetometers offer significant improvements in accuracy and interference resistance for current measurements. The study also discusses the application of quantum optical technology in high-voltage measurements, demonstrating its unique advantages in improving measurement dynamic range. However, quantum sensing technology still faces challenges in practical applications, such as technological maturity and cost. To address these issues, the research proposes a phased implementation strategy and industry-academia collaboration model. Finally, the study envisions future directions combining quantum sensing with artificial intelligence. This research provides a theoretical foundation for innovative upgrades in power system measurement technology.展开更多
A measuring principle for acoustic power in plastics ultrasonic welding process is introduced in this paper. Signal detection circuits of current, voltage, frequency, power for ultrasonic transducer of plastic ultraso...A measuring principle for acoustic power in plastics ultrasonic welding process is introduced in this paper. Signal detection circuits of current, voltage, frequency, power for ultrasonic transducer of plastic ultrasonic welder are developed. A computer controlled measuring system is designed to sample the signals of welding process parameters. By using the designed system, the acoustic power curve during welding is calculated, saved, and displayed. And the relation between fusion state of plastics workpieces and input energy of joint is analyzed.展开更多
In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating(ECRH) system for EAST is presented. This method requires measurements of the water flow through the cooling cir...In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating(ECRH) system for EAST is presented. This method requires measurements of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature stability is controlled to obtain more accurate results.The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. Also, a novel temperature calibration method is proposed. This kind of calibration method is accurate and effective, and can be easily implemented.展开更多
A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationsh...A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationship between the frequency of radio frequency(RF)signal and the power ratio of two optical signals output by two I/Q modulators.The frequency of RF signal can be derived by measuring the optical power of the optical signals output by two I/Q modulators.The measurement range and measurement error can be adjusted by controlling the delay amount of the electrical delay line.The feasibility of the scheme is verified,and the corresponding measurement range and measurement error of the system under different delay amounts of the electrical delay line are given.Compared with previous IFM schemes,the structure of this scheme is simple.Polarization devices,a photodetector and an electrical power meter are not used,which reduces the impact of the environmental disturbance on the system and the cost of the system.In simulation,the measurement range can reach 0 GHz-24.5 GHz by adjusting the delay amount of the electrical delay lineτ=20 ps.The measurement error of the scheme is better at low frequency,and the measurement error of low frequency 0 GHz-9.6 GHz can reach-0.1 GHz to+0.05 GHz.展开更多
AIM:To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two ins...AIM:To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis(LASIK). METHODS:One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea:steep keratometry(Ks),flat keratometry(Kf),mean keratometry(Km),and astigmatism(Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation(Sw)the coefficient of repeatability(R),the coefficient of variation(Co V),and the intraclass correlation coefficient(ICC). Agreement between instruments was tested with the BlandAltman method by calculating the 95% limits of agreement(95% Lo A).RESULTS:In keratoconic eyes,the intra-examiner and inter-examiner ICC were 〉0.95. As compared with measurement by high-resolution Placido disk-based topography,the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf(0.32 vs 0.88),Ks(0.61 vs 0.88),and Km(0.32 vs 0.84)but higher for Ks-Kf(0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% Lo A were-1.28 to +0.55 for Kf,-1.36 to +0.99 for Ks,-1.08 to +0.50 for Km,and-1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes,the intra-examiner andinter-examiner ICC were 〉0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf,0.21 vs 0.88 for Ks,0.17 vs 0.86 for Km,and 0.28 vs 0.33 for Ks-Kf. The inter-examiner R was 0.09 vs 0.64 for Kf,0.15 vs 0.56 for Ks,0.09 vs 0.59 for Km,and 0.18 vs 0.23 for Ks-Kf. The 95% Lo A were-0.54 to +0.58 for Kf,-0.51 to +0.53 for Ks and Km,and-0.28 to +0.27 for Ks-Kf. CONCLUSION:As compared with Placido disk-based topography,the high-resolution rotating Scheimpflug camera provides more repeatable and reproducible measurements of Ks,Kf and Ks in keratoconic and post-LASIK eyes. Agreement between instruments is fair in keratoconus and very good in post-LASIK eyes.展开更多
To ensure the performance of the optical system, the machining accuracy of lens with long focal lengths is required to ensure the image quality. A new method for lens transmission wavefront power spectral density (PSD...To ensure the performance of the optical system, the machining accuracy of lens with long focal lengths is required to ensure the image quality. A new method for lens transmission wavefront power spectral density (PSD) in mid-frequency domain measurement using binary phase computer-generated hologram (CGH) is presented. This technique is widely applicable and is particularly useful for measuring large-size lenses with long focal lengths. A comparison experiment of the CGH measurement with results from a Fizeau sphere interferometry method is carried out to verify the accuracy and convenience of the measurement. Furthermore, measurement uncertainty due to CGH fabrication process is analysed. Analysis of the CGH test showed the overall accuracy of less than 1 nm RMS for a sphere lens with over 30 m focal length and Φ410 mm clear aperture. CGH can provide reference spheres with high precision, in the meantime greatly shorten air space, thus reducing the effect of vibration and air turbulence, therefore is of great importance for lens transmission wavefront PSD measurement. The realization of high precision, high efficiency and nondestructive testing of long focal-lens wavefront PSD ensure the ultra-precision and certainty level of machining, hence improving the comprehensive performance of the optical system.展开更多
Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole direc...Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole directional coupler has been designed and manufactured for the 105 GHz/500 kW ECRH system on the J-TEXT tokamak.During the design process,we established the relationships between hole parameters and coupling characteristics based on the multi-hole coupling method and small-hole coupling theory.High-power tests have been carried out.The results indicated the reasonability of the theoretical design and practicality of the fabricated directional coupler.Sources of test errors have been discussed in detail,and the influences of spurious modes on the directional couplers have been emphatically analyzed.展开更多
On the basis of welding transformer circuit model, a new measuring method was proposed. This method measures the peak angle of the welding current, and then calculates the dynamic power factor in each half-wave. An ar...On the basis of welding transformer circuit model, a new measuring method was proposed. This method measures the peak angle of the welding current, and then calculates the dynamic power factor in each half-wave. An artificial neural network is trained and used to generate simulation data for the analytical solution, i.e. a high-order binary polynomial, which can be easily adopted to calculate the power factor online. The tailored sensing and computing system ensures that the method possesses a real-time computational capacity and satisfying accuracy. A DSP-based resistance spot welding monitoring system was developed to perform ANN computation. The experimental results suggest that this measuring method is feasible.展开更多
Despite the increasing popularity of mechanized coal mining, there are no convenient and accurate means available to measure the loads of powered supports. The measurement of such loads is important for monitoring min...Despite the increasing popularity of mechanized coal mining, there are no convenient and accurate means available to measure the loads of powered supports. The measurement of such loads is important for monitoring mine pressure and ensuring production safety. The load-carrying features of a powered support were used to develop a method for load measurement using the mag-netoelastic principle. A cross bridge-type magnetoelastic stress sensor was designed for the support structures to measure the different parts of the supports. Tests on single-body hydraulic cylinders and simulated linkages showed that an approximately linear relationship between the values of the sensor output signal and the loads borne by the hydraulic cylinders or linkages. The results were used to analyze the load-carrying measurements of powered supports with the cross bridge-type magnetoelastic stress sensor.展开更多
Pneumatic system has been widely used throughout industry, and it consumes more than billions kW h of electricity one year all over the world. So as to improve the efficiency of pneumatic system, its power evaluation ...Pneumatic system has been widely used throughout industry, and it consumes more than billions kW h of electricity one year all over the world. So as to improve the efficiency of pneumatic system, its power evaluation as well as measurement methods should be proposed, and their applicability should be validated. In this paper, firstly, power evaluation and measurement methods of pneumatic system were introduced for the first time. Secondly, based on the proposed methods, power distributions in pneumatic system was analyzed. Thirdly, through the analysis on pneumatic efficiencies of typical compressors and pneumatic components, the applicability of the proposed methods were validated. It can be concluded that, first of all, the proposed methods to evaluation and measurement the power of pneumatic system were efficient. Furthermore, the pneumatic power efficiencies of pneumatic system in the air production and cleaning procedure are respectively about 35%–75% and 85%–90%. Moreover, the pneumatic power efficiencies of pneumatic system in the transmission and consumption procedures are about 70%–85% and 10%–35%. And the total pneumatic power efficiency of pneumatic system is about 2%–20%, which varies largely with the system configuration. This paper provides a method to analyze and measure the power of pneumatic system, lay a foundation for the optimization and energy-saving design of pneumatic system.展开更多
An accurate detection of the effective values of electric voltage and current from high frequency power generators is a precondition for the development of smart electrotomes. In this light, an energy detection system...An accurate detection of the effective values of electric voltage and current from high frequency power generators is a precondition for the development of smart electrotomes. In this light, an energy detection system based on personal computer (PC) is developed hereby. It senses voltage and current in isolation from generators with transformers, and then the measured values are amplified, filtered, transformed into single-ended signals and converted to RMS. The detected signals are transformed into digital signals through Data Acquisition Card (DAQ) and the data are processed with quadratic fit in Labview. Finally, the controller completes constant power output. The experiment results indicate that the energy detection system can measure the output parameters precisely and the controller can achieve constant power control.展开更多
Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the gallopin...Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the galloping mechanism, this paper proposes an online monitoring system for tracking galloping profile of power transmission lines based on wireless inertial measurement units (WIMUs). The system is composed of three modules: wireless inertial measurement nodes, monitoring base station, and remote monitoring station. After detailing the hardware system, the corresponding software which positions and displays galloping profile of the transmission line in real-time is outlined. The feasibility of the proposed on-line monitoring system is demonstrated through a series of experiments at the State Grid Key Laboratory of Power Overhead Transmission Line Galloping (Zhengzhou, China) by taking into account different vibration patterns.展开更多
Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error...Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error due to the effect of bending waves. In a two-dimensional quasi-longitudinal wave held, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Its axial component is proportional to two imaginary parts of cross spectral densities and in the measurement, it is measured by a pair of two-transducer arrays. In a one-dimensional quasi-longitudinal wave field, the intensity variation is zero, the intensity is proportional to only one imaginary part of a cross spectral density and it can be measured using a two-transducer array. If bending and quasi-longitudinal waves coexist and the contribution from bending waves cannot be eliminated or reduced to a certain extent, the measured quasi-longitudinal wave intensity will contain a large error. The results measured on the three-beam structure show that quasi-longitudinal wave intensity can be accurately measured using the intensity technique when bending waves are negligible in comparison with quasi-longitudinal waves.展开更多
Intuitionistic hesitant fuzzy set(IHFS)is amixture of two separated notions called intuitionistic fuzzy set(IFS)and hesitant fuzzy set(HFS),as an important technique to cope with uncertain and awkward information in r...Intuitionistic hesitant fuzzy set(IHFS)is amixture of two separated notions called intuitionistic fuzzy set(IFS)and hesitant fuzzy set(HFS),as an important technique to cope with uncertain and awkward information in realistic decision issues.IHFS contains the grades of truth and falsity in the formof the subset of the unit interval.The notion of IHFS was defined by many scholars with different conditions,which contain several weaknesses.Here,keeping in view the problems of already defined IHFSs,we will define IHFS in another way so that it becomes compatible with other existing notions.To examine the interrelationship between any numbers of IHFSs,we combined the notions of power averaging(PA)operators and power geometric(PG)operators with IHFSs to present the idea of intuitionistic hesitant fuzzy PA(IHFPA)operators,intuitionistic hesitant fuzzy PG(IHFPG)operators,intuitionistic hesitant fuzzy power weighted average(IHFPWA)operators,intuitionistic hesitant fuzzy power ordered weighted average(IHFPOWA)operators,intuitionistic hesitant fuzzy power ordered weighted geometric(IHFPOWG)operators,intuitionistic hesitant fuzzy power hybrid average(IHFPHA)operators,intuitionistic hesitant fuzzy power hybrid geometric(IHFPHG)operators and examined as well their fundamental properties.Some special cases of the explored work are also discovered.Additionally,the similarity measures based on IHFSs are presented and their advantages are discussed along examples.Furthermore,we initiated a new approach to multiple attribute decision making(MADM)problem applying suggested operators and a mathematical model is solved to develop an approach and to establish its common sense and adequacy.Advantages,comparative analysis,and graphical representation of the presented work are elaborated to show the reliability and effectiveness of the presented works.展开更多
Currently a large effort is being done with the intention to educate people about how much energy each electrical appliance uses in their houses, since this knowledge is the fundamental basis of energy efficiency prog...Currently a large effort is being done with the intention to educate people about how much energy each electrical appliance uses in their houses, since this knowledge is the fundamental basis of energy efficiency programs that can be managed by the household owners. This paper presents a simple yet functional non-intrusive method for electric power measurement that can be applied in energy efficiency programs, in order to provide a better knowledge of the energy consumption of the appliances in a home.展开更多
The measuring system for estimation of power of wind flow generated by the train movement has been created. The advantages of the proposed system are the cheapness and simple design. With its simplicity of design and ...The measuring system for estimation of power of wind flow generated by the train movement has been created. The advantages of the proposed system are the cheapness and simple design. With its simplicity of design and easy build-up of channels, designed measuring system can be used for a wide range of technical problems. This paper describes the design process, validation and conducting the first field test of this measuring system.展开更多
The regulated gaseous emissions from 2 China-V compressed natural gas(CNG)buses and 2 China-V diesel buses were investigated using a portable emissions measurement system(PEMS)under real road driving conditions.Compar...The regulated gaseous emissions from 2 China-V compressed natural gas(CNG)buses and 2 China-V diesel buses were investigated using a portable emissions measurement system(PEMS)under real road driving conditions.Compared to diesel buses,CNG buses emit less NOx pollutants,but more HC and CO pollutants based on the test results obtained in this paper.In order to evaluate the pollutant emission status of CNG buses in Beijing,an instantaneous emission model as a function of vehicle speed and vehicle specific power(VSP)was developed and validated based on emission data taken from one CNG bus.The input of the instantaneous emission model consists of driving cycle,vehicle parameters,road conditions,ambient conditions and accessory use,all of which were used to calculate the instantaneous vehicle specific power(VSP).For the core model,a group of pollutant emission maps represented as functions of vehicle speed and VSP were used to calculate the second by second emission rates.Finally,the instantaneous emission rates,emission factors and fuel consumption over the selected driving cycle could be obtained as the model outputs.The predicted results for the emissions and fuel consumption of the CNG bus were very close to the tested emission data.The prediction errors for emission factors and fuel consumption varied in the range of-1.6 2%to-5.8%.展开更多
A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider ...A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.展开更多
The novel quantitative assessment method using transmission line measurement was developed. A new style of stability criterion was suggested which is based on the line measurement. The stability indices for lines, cut...The novel quantitative assessment method using transmission line measurement was developed. A new style of stability criterion was suggested which is based on the line measurement. The stability indices for lines, cutsets and power system according to features of transient energy in the lines were given, which not only provide a reliable and accurate assessment of the transient stability of power system, but also can be used to assess the effect of lines and cutsets on the transient stability and identify the weak transmission segment. Examples were presented by simulation on the IEEE-39 buses test system.展开更多
文摘The accuracy of power system measurements directly affects the safe and stable operation of power grids. This study explores the application prospects of quantum sensing technology in power system measurements. The research first analyzes the limitations of traditional measurement techniques, such as electromagnetic interference sensitivity and measurement accuracy bottlenecks. It then introduces the basic principles of quantum sensing, including concepts like quantum entanglement and superposition states. Through theoretical analysis and numerical simulations, the study assesses the potential advantages of quantum sensors in current, voltage, and magnetic field measurements. Results show that quantum magnetometers offer significant improvements in accuracy and interference resistance for current measurements. The study also discusses the application of quantum optical technology in high-voltage measurements, demonstrating its unique advantages in improving measurement dynamic range. However, quantum sensing technology still faces challenges in practical applications, such as technological maturity and cost. To address these issues, the research proposes a phased implementation strategy and industry-academia collaboration model. Finally, the study envisions future directions combining quantum sensing with artificial intelligence. This research provides a theoretical foundation for innovative upgrades in power system measurement technology.
文摘A measuring principle for acoustic power in plastics ultrasonic welding process is introduced in this paper. Signal detection circuits of current, voltage, frequency, power for ultrasonic transducer of plastic ultrasonic welder are developed. A computer controlled measuring system is designed to sample the signals of welding process parameters. By using the designed system, the acoustic power curve during welding is calculated, saved, and displayed. And the relation between fusion state of plastics workpieces and input energy of joint is analyzed.
基金supported by the National Magnetic Confinement Fusion Science Program of China (Grant Nos.2011GB102000, 2015GB103000)
文摘In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating(ECRH) system for EAST is presented. This method requires measurements of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature stability is controlled to obtain more accurate results.The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. Also, a novel temperature calibration method is proposed. This kind of calibration method is accurate and effective, and can be easily implemented.
基金the National Key Research and Development Program of China(Grant No.2018YFB1801003)the National Natural Science Foundation of China(Grant Nos.61525501 and 61827817)the Beijing Natural Science Foundation,China(Grant No.4192022).
文摘A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationship between the frequency of radio frequency(RF)signal and the power ratio of two optical signals output by two I/Q modulators.The frequency of RF signal can be derived by measuring the optical power of the optical signals output by two I/Q modulators.The measurement range and measurement error can be adjusted by controlling the delay amount of the electrical delay line.The feasibility of the scheme is verified,and the corresponding measurement range and measurement error of the system under different delay amounts of the electrical delay line are given.Compared with previous IFM schemes,the structure of this scheme is simple.Polarization devices,a photodetector and an electrical power meter are not used,which reduces the impact of the environmental disturbance on the system and the cost of the system.In simulation,the measurement range can reach 0 GHz-24.5 GHz by adjusting the delay amount of the electrical delay lineτ=20 ps.The measurement error of the scheme is better at low frequency,and the measurement error of low frequency 0 GHz-9.6 GHz can reach-0.1 GHz to+0.05 GHz.
文摘AIM:To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis(LASIK). METHODS:One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea:steep keratometry(Ks),flat keratometry(Kf),mean keratometry(Km),and astigmatism(Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation(Sw)the coefficient of repeatability(R),the coefficient of variation(Co V),and the intraclass correlation coefficient(ICC). Agreement between instruments was tested with the BlandAltman method by calculating the 95% limits of agreement(95% Lo A).RESULTS:In keratoconic eyes,the intra-examiner and inter-examiner ICC were 〉0.95. As compared with measurement by high-resolution Placido disk-based topography,the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf(0.32 vs 0.88),Ks(0.61 vs 0.88),and Km(0.32 vs 0.84)but higher for Ks-Kf(0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% Lo A were-1.28 to +0.55 for Kf,-1.36 to +0.99 for Ks,-1.08 to +0.50 for Km,and-1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes,the intra-examiner andinter-examiner ICC were 〉0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf,0.21 vs 0.88 for Ks,0.17 vs 0.86 for Km,and 0.28 vs 0.33 for Ks-Kf. The inter-examiner R was 0.09 vs 0.64 for Kf,0.15 vs 0.56 for Ks,0.09 vs 0.59 for Km,and 0.18 vs 0.23 for Ks-Kf. The 95% Lo A were-0.54 to +0.58 for Kf,-0.51 to +0.53 for Ks and Km,and-0.28 to +0.27 for Ks-Kf. CONCLUSION:As compared with Placido disk-based topography,the high-resolution rotating Scheimpflug camera provides more repeatable and reproducible measurements of Ks,Kf and Ks in keratoconic and post-LASIK eyes. Agreement between instruments is fair in keratoconus and very good in post-LASIK eyes.
文摘To ensure the performance of the optical system, the machining accuracy of lens with long focal lengths is required to ensure the image quality. A new method for lens transmission wavefront power spectral density (PSD) in mid-frequency domain measurement using binary phase computer-generated hologram (CGH) is presented. This technique is widely applicable and is particularly useful for measuring large-size lenses with long focal lengths. A comparison experiment of the CGH measurement with results from a Fizeau sphere interferometry method is carried out to verify the accuracy and convenience of the measurement. Furthermore, measurement uncertainty due to CGH fabrication process is analysed. Analysis of the CGH test showed the overall accuracy of less than 1 nm RMS for a sphere lens with over 30 m focal length and Φ410 mm clear aperture. CGH can provide reference spheres with high precision, in the meantime greatly shorten air space, thus reducing the effect of vibration and air turbulence, therefore is of great importance for lens transmission wavefront PSD measurement. The realization of high precision, high efficiency and nondestructive testing of long focal-lens wavefront PSD ensure the ultra-precision and certainty level of machining, hence improving the comprehensive performance of the optical system.
基金supported by the National Key Research and Development Program of China (Nos.2017YFE0300200 and 2017YFE0300204)in part by National Natural Science Foundation of China(No.51821005).
文摘Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole directional coupler has been designed and manufactured for the 105 GHz/500 kW ECRH system on the J-TEXT tokamak.During the design process,we established the relationships between hole parameters and coupling characteristics based on the multi-hole coupling method and small-hole coupling theory.High-power tests have been carried out.The results indicated the reasonability of the theoretical design and practicality of the fabricated directional coupler.Sources of test errors have been discussed in detail,and the influences of spurious modes on the directional couplers have been emphatically analyzed.
基金The National Natural Science Foundation of China (No 50575145)
文摘On the basis of welding transformer circuit model, a new measuring method was proposed. This method measures the peak angle of the welding current, and then calculates the dynamic power factor in each half-wave. An artificial neural network is trained and used to generate simulation data for the analytical solution, i.e. a high-order binary polynomial, which can be easily adopted to calculate the power factor online. The tailored sensing and computing system ensures that the method possesses a real-time computational capacity and satisfying accuracy. A DSP-based resistance spot welding monitoring system was developed to perform ANN computation. The experimental results suggest that this measuring method is feasible.
文摘Despite the increasing popularity of mechanized coal mining, there are no convenient and accurate means available to measure the loads of powered supports. The measurement of such loads is important for monitoring mine pressure and ensuring production safety. The load-carrying features of a powered support were used to develop a method for load measurement using the mag-netoelastic principle. A cross bridge-type magnetoelastic stress sensor was designed for the support structures to measure the different parts of the supports. Tests on single-body hydraulic cylinders and simulated linkages showed that an approximately linear relationship between the values of the sensor output signal and the loads borne by the hydraulic cylinders or linkages. The results were used to analyze the load-carrying measurements of powered supports with the cross bridge-type magnetoelastic stress sensor.
基金Supported by National Natural Science Foundation of China(Grants Nos.51675020,51375028)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems
文摘Pneumatic system has been widely used throughout industry, and it consumes more than billions kW h of electricity one year all over the world. So as to improve the efficiency of pneumatic system, its power evaluation as well as measurement methods should be proposed, and their applicability should be validated. In this paper, firstly, power evaluation and measurement methods of pneumatic system were introduced for the first time. Secondly, based on the proposed methods, power distributions in pneumatic system was analyzed. Thirdly, through the analysis on pneumatic efficiencies of typical compressors and pneumatic components, the applicability of the proposed methods were validated. It can be concluded that, first of all, the proposed methods to evaluation and measurement the power of pneumatic system were efficient. Furthermore, the pneumatic power efficiencies of pneumatic system in the air production and cleaning procedure are respectively about 35%–75% and 85%–90%. Moreover, the pneumatic power efficiencies of pneumatic system in the transmission and consumption procedures are about 70%–85% and 10%–35%. And the total pneumatic power efficiency of pneumatic system is about 2%–20%, which varies largely with the system configuration. This paper provides a method to analyze and measure the power of pneumatic system, lay a foundation for the optimization and energy-saving design of pneumatic system.
文摘An accurate detection of the effective values of electric voltage and current from high frequency power generators is a precondition for the development of smart electrotomes. In this light, an energy detection system based on personal computer (PC) is developed hereby. It senses voltage and current in isolation from generators with transformers, and then the measured values are amplified, filtered, transformed into single-ended signals and converted to RMS. The detected signals are transformed into digital signals through Data Acquisition Card (DAQ) and the data are processed with quadratic fit in Labview. Finally, the controller completes constant power output. The experiment results indicate that the energy detection system can measure the output parameters precisely and the controller can achieve constant power control.
文摘Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the galloping mechanism, this paper proposes an online monitoring system for tracking galloping profile of power transmission lines based on wireless inertial measurement units (WIMUs). The system is composed of three modules: wireless inertial measurement nodes, monitoring base station, and remote monitoring station. After detailing the hardware system, the corresponding software which positions and displays galloping profile of the transmission line in real-time is outlined. The feasibility of the proposed on-line monitoring system is demonstrated through a series of experiments at the State Grid Key Laboratory of Power Overhead Transmission Line Galloping (Zhengzhou, China) by taking into account different vibration patterns.
文摘Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error due to the effect of bending waves. In a two-dimensional quasi-longitudinal wave held, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Its axial component is proportional to two imaginary parts of cross spectral densities and in the measurement, it is measured by a pair of two-transducer arrays. In a one-dimensional quasi-longitudinal wave field, the intensity variation is zero, the intensity is proportional to only one imaginary part of a cross spectral density and it can be measured using a two-transducer array. If bending and quasi-longitudinal waves coexist and the contribution from bending waves cannot be eliminated or reduced to a certain extent, the measured quasi-longitudinal wave intensity will contain a large error. The results measured on the three-beam structure show that quasi-longitudinal wave intensity can be accurately measured using the intensity technique when bending waves are negligible in comparison with quasi-longitudinal waves.
基金supported by“Algebra and Applications Research Unit,Division of Computational Science,Faculty of Science,Prince of Songkla University”.
文摘Intuitionistic hesitant fuzzy set(IHFS)is amixture of two separated notions called intuitionistic fuzzy set(IFS)and hesitant fuzzy set(HFS),as an important technique to cope with uncertain and awkward information in realistic decision issues.IHFS contains the grades of truth and falsity in the formof the subset of the unit interval.The notion of IHFS was defined by many scholars with different conditions,which contain several weaknesses.Here,keeping in view the problems of already defined IHFSs,we will define IHFS in another way so that it becomes compatible with other existing notions.To examine the interrelationship between any numbers of IHFSs,we combined the notions of power averaging(PA)operators and power geometric(PG)operators with IHFSs to present the idea of intuitionistic hesitant fuzzy PA(IHFPA)operators,intuitionistic hesitant fuzzy PG(IHFPG)operators,intuitionistic hesitant fuzzy power weighted average(IHFPWA)operators,intuitionistic hesitant fuzzy power ordered weighted average(IHFPOWA)operators,intuitionistic hesitant fuzzy power ordered weighted geometric(IHFPOWG)operators,intuitionistic hesitant fuzzy power hybrid average(IHFPHA)operators,intuitionistic hesitant fuzzy power hybrid geometric(IHFPHG)operators and examined as well their fundamental properties.Some special cases of the explored work are also discovered.Additionally,the similarity measures based on IHFSs are presented and their advantages are discussed along examples.Furthermore,we initiated a new approach to multiple attribute decision making(MADM)problem applying suggested operators and a mathematical model is solved to develop an approach and to establish its common sense and adequacy.Advantages,comparative analysis,and graphical representation of the presented work are elaborated to show the reliability and effectiveness of the presented works.
文摘Currently a large effort is being done with the intention to educate people about how much energy each electrical appliance uses in their houses, since this knowledge is the fundamental basis of energy efficiency programs that can be managed by the household owners. This paper presents a simple yet functional non-intrusive method for electric power measurement that can be applied in energy efficiency programs, in order to provide a better knowledge of the energy consumption of the appliances in a home.
文摘The measuring system for estimation of power of wind flow generated by the train movement has been created. The advantages of the proposed system are the cheapness and simple design. With its simplicity of design and easy build-up of channels, designed measuring system can be used for a wide range of technical problems. This paper describes the design process, validation and conducting the first field test of this measuring system.
基金Supported by the National Key Research and Development Plan(2016YFC0208005)the National Natural Science Foundation of China(51576016)
文摘The regulated gaseous emissions from 2 China-V compressed natural gas(CNG)buses and 2 China-V diesel buses were investigated using a portable emissions measurement system(PEMS)under real road driving conditions.Compared to diesel buses,CNG buses emit less NOx pollutants,but more HC and CO pollutants based on the test results obtained in this paper.In order to evaluate the pollutant emission status of CNG buses in Beijing,an instantaneous emission model as a function of vehicle speed and vehicle specific power(VSP)was developed and validated based on emission data taken from one CNG bus.The input of the instantaneous emission model consists of driving cycle,vehicle parameters,road conditions,ambient conditions and accessory use,all of which were used to calculate the instantaneous vehicle specific power(VSP).For the core model,a group of pollutant emission maps represented as functions of vehicle speed and VSP were used to calculate the second by second emission rates.Finally,the instantaneous emission rates,emission factors and fuel consumption over the selected driving cycle could be obtained as the model outputs.The predicted results for the emissions and fuel consumption of the CNG bus were very close to the tested emission data.The prediction errors for emission factors and fuel consumption varied in the range of-1.6 2%to-5.8%.
基金supported by the National Natural Science Foundation of China (Nos.Y8113C005C and U1832132)。
文摘A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.
基金National Natural Science Foundation ofChina( No.5 99770 0 1)
文摘The novel quantitative assessment method using transmission line measurement was developed. A new style of stability criterion was suggested which is based on the line measurement. The stability indices for lines, cutsets and power system according to features of transient energy in the lines were given, which not only provide a reliable and accurate assessment of the transient stability of power system, but also can be used to assess the effect of lines and cutsets on the transient stability and identify the weak transmission segment. Examples were presented by simulation on the IEEE-39 buses test system.