With the rapid development of electrical power systems,ensuring the accuracy and reliability of power transmis-sion has become particularly crucial.The secondary cable line calibrator for current transformers(CT)plays...With the rapid development of electrical power systems,ensuring the accuracy and reliability of power transmis-sion has become particularly crucial.The secondary cable line calibrator for current transformers(CT)plays an essential role in calibrating electrical power systems.It is not only related to the safe operation of the system but also directly im-pacts the accuracy of energy metering.This study aims to design and analyze an efficient CT secondary cable line calibra-tor to explore its application effects in the power system.By thoroughly analyzing the characteristics of CT secondary ca-ble lines and the design requirements of the calibrator,this paper proposes an innovative design scheme for the calibrator.This device demonstrates significant effects in enhancing the accuracy and stability of power system calibration,providing robust technical support for the optimization and upgrade of the power system.This research not only offers a theoretical basis and practical guidance for the design and application of CT secondary cable line calibrators but also contributes new ideas and methods for the precise calibration and efficient management of the power system.展开更多
Aim: Measurement of B-type natriuretic peptide (BNP) is widely used as a diagnostic and risk assessment tool for cardiovascular disease. Recent studies have demonstrated that BNP-32 and its precursor proBNP circulate ...Aim: Measurement of B-type natriuretic peptide (BNP) is widely used as a diagnostic and risk assessment tool for cardiovascular disease. Recent studies have demonstrated that BNP-32 and its precursor proBNP circulate in the blood stream, and that most commercial BNP immunoassays measure both forms. However, recombinant or synthetic BNP-32 is used as the standard for those BNP immunoassays. This gap between clinical samples and the standard might be a potential source of variation in BNP measurements among assays. The purpose of this study is to validate a more suitable calibrator for BNP immunoassays. Methods: External BNP calibrators containing both BNP-32 and glycosylated proBNP were prepared at two concentration levels. Target BNP concentrations of the low and high levels were 40 and 160 pg/mL, respectively. And to reflect clinical samples, the molar ratios of BNP-32 to glycosylated proBNP in these concentration levels were adjusted to 50:50 and 25:75, respectively. BNP concentrations of plasma samples along with the external BNP calibrators were measured at two commercial labs and using an automated analyzer MI02 Shionogi®BNP (MI02). These samples and the calibrators were also measured using an immunoradiometric assay (IRMA) as a standard assay procedure. Concentrations of the plasma samples measured at the labs or using the MI02 were adjusted according to a comparison of the measured concentrations of the external BNP calibrators with the IRMA. Results: After measured concentrations of the plasma samples were adjusted using the external BNP calibrators, the correlation between each measurement and the IRMA was improved. The range of the slopes according to Passing-Bablok regression analysis narrowed from 0.628 - 0.955 to 0.911 - 1.005. Conclusions: Our data suggests that a mixture of BNP-32 and glycosylated proBNP at different ratios by concentration level is suitable for calibration to minimize variations in BNP measurements among immunoassays.展开更多
Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrat...Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrator for the famous 4-20 mA electrical signaling scheme. The loop calibrator generates a linear current signal from 4 to 20 mA over a 250 ? typical process instrument load for calibration. The realization of the loop calibrator relies on a voltage-to-current converter to build a constant current source. The voltage controlled constant current source is built from discrete components and an op-amp to keep the cost low. Results from simulations and the prototype demonstrate the performance of the 4-20 mA loop calibrator which utilizes a greatly reduced number of components. The cost of these components is approximately 34% of the least expensive calibrator sampled, though other production costs are not included. This conclusion reinforces the fact that loop calibrators can be cheaper.展开更多
Due to the complex erection environment of various types of automatic stations,the provincial meteorological inspection department is difficult to carry out this work in terms of equipment or staffing. For this reason...Due to the complex erection environment of various types of automatic stations,the provincial meteorological inspection department is difficult to carry out this work in terms of equipment or staffing. For this reason,a portable temperature sensor calibrator was developed,and it uses semiconductor refrigeration technology to increase and decrease temperature quickly. It uses an intelligent PID temperature controller as a control device to provide a stable temperature environment; it is small,light and easy to operate,and it provides technical support for the calibration of temperature sensors. The structure and working principle of this equipment were analyzed,and its performance was tested. All the indicators could meet the requirements of field calibration. The calibrator will provide a strong guarantee for the reliability of temperature data obtained at automatic meteorological stations.展开更多
Observatories typically deploy all-sky cameras for monitoring cloud cover and weather conditions.However,many of these cameras lack scientific-grade sensors,r.esulting in limited photometric precision,which makes calc...Observatories typically deploy all-sky cameras for monitoring cloud cover and weather conditions.However,many of these cameras lack scientific-grade sensors,r.esulting in limited photometric precision,which makes calculating the sky area visibility distribution via extinction measurement challenging.To address this issue,we propose the Photometry-Free Sky Area Visibility Estimation(PFSAVE)method.This method uses the standard magnitude of the faintest star observed within a given sky area to estimate visibility.By employing a pertransformation refitting optimization strategy,we achieve a high-precision coordinate transformation model with an accuracy of 0.42 pixels.Using the results of HEALPix segmentation is also introduced to achieve high spatial resolution.Comprehensive analysis based on real allsky images demonstrates that our method exhibits higher accuracy than the extinction-based method.Our method supports both manual and robotic dynamic scheduling,especially under partially cloudy conditions.展开更多
High-precision magnetic field measurements are crucial for understanding Earth’s internal structure,space environment,and dynamic geomagnetic variations.Data from the Fluxgate Magnetometer (FGM) on the Macao Science ...High-precision magnetic field measurements are crucial for understanding Earth’s internal structure,space environment,and dynamic geomagnetic variations.Data from the Fluxgate Magnetometer (FGM) on the Macao Science Satellite-1A (MSS-1A),added to data from other space-based magnetometers,should increase significantly the ability of scientists to observe changes in Earth’s magnetic field over time and space.Additionally,the MSS-1A’s FGM is intended to help identify magnetic disturbances affecting the spacecraft itself.This report focuses on the in-flight calibration of the MSS-1 FGM.A scalar calibration,independent of geomagnetic field models,was performed to correct offsets,sensitivities,and misalignment angles of the FGM.Using seven months of data,we find that the in-flight calibration parameters show good stability.We determined Euler angles describing the rotational relationship between the FGM and the Advanced Stellar Compass (ASC) coordinate system using two approaches:calibration with the CHAOS-7 geomagnetic field model,and simultaneous estimation of Euler angles and Gaussian spherical harmonic coefficients through self-consistent modeling.The accuracy of Euler angles describing the rotation was better than 18 arcsec.The calibrated FGM data exhibit good agreement with the calibrated data of the Vector Field Magnetometer (VFM),which is the primary vector magnetometer of the satellite.These calibration efforts have significantly improved the accuracy of the FGM measurements,which are now providing reliable data for geomagnetic field studies that promise to advance our understanding of the Earth’s magnetic environment.展开更多
1.A.Mertha,“‘Stressing Out’:Cadre Calibration and Affective Proximity to the CCP in Reform-Era China”,The China Quarterly,Vol.229,2017,pp.64-85.2.B.L.McCormick,“Book Review of‘The Chinese Communist Party's C...1.A.Mertha,“‘Stressing Out’:Cadre Calibration and Affective Proximity to the CCP in Reform-Era China”,The China Quarterly,Vol.229,2017,pp.64-85.2.B.L.McCormick,“Book Review of‘The Chinese Communist Party's Capacity to Rule:Ideology,Legitimacy and Party Cohesion’”,The China Journal,Vol.77,2017,pp.161-163.展开更多
Accurate calibration of surgical instruments and ultrasound probes is essential for achieving high precision in image guided minimally invasive procedures.However,existing methods typically treat the calibration of th...Accurate calibration of surgical instruments and ultrasound probes is essential for achieving high precision in image guided minimally invasive procedures.However,existing methods typically treat the calibration of the needle tip and the ultrasound probe as two independent processes,lacking an integrated calibration mechanism,which often leads to cumulative errors and reduced spatial consistency.To address this challenge,we propose a joint calibration model that unifies the calibration of the surgical needle tip and the ultrasound probe within a single coordinate system.The method formulates the calibration process through a series of mathematical models and coordinate transformation models and employs a gradient descent based optimization to refine the parameters of these models.By establishing and iteratively optimizing a template coordinate system through modeling of constrained spherical motion,the proposed joint calibration model achieves submillimeter accuracy in needle tip localization.Building upon this,an N line based calibration model is developed to determine the spatial relationship between the probe and the ultrasound image plane,resulting in an average pixel deviation of only 1.2373 mm.Experimental results confirm that this unified modeling approach effectively overcomes the limitations of separate calibration schemes,significantly enhancing both precision and robustness,and providing a reliable computational model for surgical navigation systems that require high spatial accuracy without relying on ionizing radiation.展开更多
Accurate thrust assessment is crucial for characterizing the performance of micro-thrusters.This paper presents a comprehensive evaluation of the thrust generated by a needle-type indium field emission electric propul...Accurate thrust assessment is crucial for characterizing the performance of micro-thrusters.This paper presents a comprehensive evaluation of the thrust generated by a needle-type indium field emission electric propulsion(In-FEEP)micro-thruster using three methods based on a pendulum:direct thrust measurement,indirect plume momentum transfer and beam current diagnostics.The experimental setup utilized capacitive displacement sensors for force detection and a voice coil motor as a feedback actuator,achieving a resolution better than 0.1μN.Key performance factors such as ionization and plume divergence of ejected charged particles were also examined.The study reveals that the high applied voltage induces significant electrostatic interference,becoming the dominant source of error in direct thrust measurements.Beam current diagnostics and indirect plume momentum measurements were conducted simultaneously,showing strong agreement within a deviation of less than 0.2N across the operational thrust range.The results from all three methods are consistent within the error margins,verifying the reliability of the indirect measurement approach and the theoretical thrust model based on the electrical parameters of In-FEEP.展开更多
To enhance direction of arrival(DOA)estimation accuracy,this paper proposes a low-cost method for calibrating farfield steering vectors of large aperture millimeter wave radar(mmWR).To this end,we first derive the ste...To enhance direction of arrival(DOA)estimation accuracy,this paper proposes a low-cost method for calibrating farfield steering vectors of large aperture millimeter wave radar(mmWR).To this end,we first derive the steering vectors with amplitude and phase errors,assuming that mmWR works in the time-sharing mode.Then,approximate relationship between the near-field calibration steering vector and the far-field calibration steering vector is analyzed,which is used to accomplish the mapping between the two of them.Finally,simulation results verify that the proposed method can effectively improve the angle measurement accuracy of mmWR with existing amplitude and phase errors.展开更多
A recent single-center retrospective study proposed novel combinations of hematological parameters and scoring systems for predicting severe acute pancre-atitis.While these combinations showed promising predictive per...A recent single-center retrospective study proposed novel combinations of hematological parameters and scoring systems for predicting severe acute pancre-atitis.While these combinations showed promising predictive performance,several limitations warrant consideration,including the lack of calibration,the absence of key inflammatory markers such as procalcitonin,and practical challenges in integrating these models into routine clinical workflows.To improve predictive accuracy and clinical applicability,prospective validation and the inclusion of additional variables are recommended.展开更多
In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension ...In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension Kalman filter is constructed to reduce impact brought by turntable.Then,a biaxial rotation path is designed based on the accelerometer output model,including orthogonal 22 positions and tilt 12 positions,which enhances gravity excitation on nonlinear coefficients of accelerometer.Finally,sampling is carried out for calibration and further experiments.The results of static inertial navigation experiments lasting 4000 s show that compared with the traditional method,the proposed method reduces the position error by about 390 m.展开更多
Radiation doses to patients in diagnostics and interventional radiology need to be optimized to comply with the principles of radiation protection in medical practice. This involves using specific detectors with respe...Radiation doses to patients in diagnostics and interventional radiology need to be optimized to comply with the principles of radiation protection in medical practice. This involves using specific detectors with respective diagnostic beams to carry out quality control/quality assurance tests needed to optimize patient doses in the hospital. Semiconductor detectors are used in dosimetry to verify the equipment performance and dose to patients. This work aims to assess the performance, energy dependence, and response of five commercially available semiconductor detectors in RQR, RQR-M, RQA, and RQT at Secondary Standard Dosimetry for clinical applications. The diagnostic beams were generated using Exradin A4 reference ion chamber and PTW electrometer. The ambient temperature and pressure were noted for KTP correction. The detectors designed for RQR showed good performance in RQT beams and vice versa. The detectors designed for RQR-M displayed high energy dependency in other diagnostic beams. The type of diagnostic beam quality determines the response of semiconductor detectors. Therefore, a detector should be calibrated according to the beam qualities to be measured.展开更多
EMC anechoic chamber is used for radiation emission and radiation immunity test,and the wireless performance of products needs to be tested in OTA anechoic chamber.With more and more electronic and electrical equipmen...EMC anechoic chamber is used for radiation emission and radiation immunity test,and the wireless performance of products needs to be tested in OTA anechoic chamber.With more and more electronic and electrical equipment with wireless communication function,the rapid construction of a compatible OTA test system in the existing EMC anechoic chamber can save the cost and space of enterprises and third-party laboratories that already have EMC anechoic chamber.In this paper,the OTA test system is built in the existing EMC anechoic room,the ripple calibration test is carried out according to the OTA standard,the TRP and TIS tests are carried out on two test samples with different wireless communication standards,and the test samples are taken to the OTA anechoic room for a comparison test.The comparison between the ripple calibration data and the OTA test data showed that the EMC anechoic chamber could perform OTA test without affecting the original test ability.The data results provide a basis for the implementation of EMC anechoic chamber compatibility upgrade OTA test,and provide reference for further optimization of the compatible test system,reduction of test differences,and the design of anechoic chamber integrating two test functions.展开更多
BACKGROUND The EuroSCORE II is a globally accepted tool for predicting mortality in patients undergoing cardiac surgery.However,the discriminative ability of this tool in non-European populations may be inadequate,lim...BACKGROUND The EuroSCORE II is a globally accepted tool for predicting mortality in patients undergoing cardiac surgery.However,the discriminative ability of this tool in non-European populations may be inadequate,limiting its use in other regions.AIM To evaluate the performance of EuroSCORE II in patients undergoing coronary artery bypass graft(CABG)surgery at a hospital in Bogotá,Colombia.METHODS An observational,analytical study of a retrospective cohort was designed.All patients admitted to Hospital Universitario Mayor Méderi who underwent CABG between December 2015 and May 2020 were included.In-hospital mortality was the primary outcome evaluated.Furthermore,the performance of EuroSCORE II was assessed in this population.RESULTS A total of 1009 patients were included[median age 66 years IQR=59-72,78.2%men].The overall in-hospital mortality was 5.5%(n=56).The median mortality predicted using EuroSCORE II was 1.29(IQR=0.92-2.11).Non-ST-segment elevation myocardial infarction was the most common preoperative diagnosis(54.1%),followed by ST-segment elevation myocardial infarction(19.1%)and unstable angina(14.3%).Urgent surgery was performed in 87.3%of the patients(n=881).Mortality rates in each group were as follows:Low risk 6.0%(n=45,observed-to-expected(O/E)ratio,5.6),moderate risk 3.0%(n=5,O/E ratio 1.17),high risk 5.0%(n=4,O/E ratio 0.94),and very high risk 7.6%(n=2,O/E ratio 0.71).The overall O/E ratio was 4.2.The area under the curve of EuroSCORE II was 0.55[95%confidence interval:0.48-0.63]CONCLUSION EuroSCORE II exhibited poor performance in this population owing to its low discriminative ability.This finding may be explained by the fact that the population comprised older individuals with higher ventricular function impairment.Moreover,unlike the population in which this tool was originally developed,most patients were not electively admitted for the surgery.展开更多
This paper considers the fundamental channel estimation problem for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)system in the presence of multi-cell interference.Specificall...This paper considers the fundamental channel estimation problem for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)system in the presence of multi-cell interference.Specifically,this paper focuses on both channel modelling and receiver design for interference estimation and mitigation.We propose a delay-calibrated block-wise linear model,which extracts the delay of the dominant tap of each interference as a key parameter and approximates the residual channel coefficients by the recently developed blockwise linear model.Based on the delay-calibrated block-wise linear model and the angle-domain channel sparsity,we further conceive a message passing algorithm to solve the channel estimation problem.Numerical results demonstrate the superior performance of the proposed algorithm over the state-of-the-art algorithms.展开更多
Traditional calibration method for the digital inclinometer relies on manual inspection,and results in its disadvantages of complicated process,low-efficiency and human errors easy to be introduced.To improve both the...Traditional calibration method for the digital inclinometer relies on manual inspection,and results in its disadvantages of complicated process,low-efficiency and human errors easy to be introduced.To improve both the calibration accuracy and efficiency of digital inclinometer,an automatic digital inclinometer calibration system was developed in this study,and a new display tube recognition algorithm was proposed.First,a high-precision automatic turntable was taken as the reference to calculate the indication error of the inclinometer.Then,the automatic inclinometer calibration control process and the digital inclinometer zero-setting function were formulated.For display tube recognition,a new display tube recognition algorithm combining threading method and feature extraction method was proposed.Finally,the calibration system was calibrated by photoelectric autocollimator and regular polygon mirror,and the calibration system error and repeatability were calculated via a series of experiments.The experimental results showed that the indication error of the proposed calibration system was less than 4",and the repeatability was 3.9".A digital inclinometer with the resolution of 0.1°was taken as a testing example,within the calibration points'range of[-90°,90°],the repeatability of the testing was 0.085°,and the whole testing process was less than 90 s.The digital inclinometer indication error is mainly introduced by the digital inclinometer resolution according to the uncertainty evaluation.展开更多
We developed a dedicated data analysis framework for silicon strip detector telescopes(SSDTs)of the Compact Spectrometer for Heavy-IoN Experiments(CSHINE)that addresses the challenges of processing complex signals.The...We developed a dedicated data analysis framework for silicon strip detector telescopes(SSDTs)of the Compact Spectrometer for Heavy-IoN Experiments(CSHINE)that addresses the challenges of processing complex signals.The framework integrates advanced algorithms for precise calibration,accurate particle identification,and efficient event reconstruction,aiming to account for critical experimental factors such as charge-sharing effects,multi-hit event resolution,and detector response nonuniformity.Its robust performance was demonstrated through the successful analysis of light-charged particles in the 25 MeV/u^(86)Kr+^(124)Sn experiment conducted at the first Radioactive Ion Beam Line in Lanzhou,allowing for precise extraction of physical observables,including energy,momentum,and particle type.Furthermore,utilizing the reconstructed physical information,such as the number of effective physical events and energy spectra to optimize the track recognition algorithm,the final track recognition efficiencies of approximately 90%were achieved.This framework establishes a valuable reference methodology for SSDT-based detector systems in heavy-ion reaction experiments,thereby significantly enhancing the accuracy and efficiency of data analysis in nuclear physics research.展开更多
Minor errors in the spoil deposition process,such as placing stronger materials with higher shear strength over weaker ones,can lead to potential dump failure.Irregular deposition and inadequate compaction complicate ...Minor errors in the spoil deposition process,such as placing stronger materials with higher shear strength over weaker ones,can lead to potential dump failure.Irregular deposition and inadequate compaction complicate coal spoil behaviour,neces-sitating a robust methodology for temporal monitoring.This study explores using unmanned aerial vehicles(UAV)equipped with red-green-blue(RGB)sensors for efficient data acquisition.Despite their prevalence,raw UAV data exhibit temporal inconsistency,hindering accurate assessments of changes over time which could be attributed to radiometric errors.To this end,the study introduces an empirical line calibration with invariant targets(ELC-IT),for precise calibration across diverse scenes,particularly in the context of UAV imagery used to monitor the evolving nature of spoil dumps.To evaluate the effec-tiveness of this calibration approach,accuracy assessment of an object-based classification is conducted on both calibrated and uncalibrated data.This classification involves several steps:performing segmentation,carrying out feature extraction,and integrating the extracted features and ground truth labels collected over the time period of UAV image capture into machine learning pipelines.Calibrated RGB data exhibit a substantial performance advantage,achieving a 90.7%overall accuracy for spoil pile classification using ensemble(subspace discriminant),representing a noteworthy 7%improvement compared to classifying uncalibrated data.The study highlights the critical role of data calibration in optimising UAV effectiveness for spatio-temporal mine dump monitoring.These findings play a crucial role in informing and refining sustainable management practices within the domain of mine waste management.展开更多
In clinical environments,the prolonged utilization of polarization equipment can result in theaccumulation of errors over extended periods.The absence of expeditious calibration techniques in clinical practice present...In clinical environments,the prolonged utilization of polarization equipment can result in theaccumulation of errors over extended periods.The absence of expeditious calibration techniques in clinical practice presents a significant obstacle in preserving the precision and dependability of these instruments.To address this challenge,we propose an innovative research study that presents a comprebersive calibration system specifically designed for the calibration of the backscattering Muellet matrix measurement system,enabling swift online calibration acroes various scenarios.This system employs an external calibration framework for rmal-time adjust-ment of the polarizer's initial angle,oversecing the rotation of PSG and PSA motors through position measurement and control procedures,with light intensity monitored by a camera.By incorporating moment um concepts and the Adam optimization algorithm,we enhance conver-gence speed,mitigate noise,and improve calibration accuracy.Experimental results showcase the exceptional precision,speed,and robustness of oрroposed method,achieving high acсuracy and minimal error,thereby offering a promising solution for maintaining the reliabilit y of polarization equipment in clinical settings.展开更多
文摘With the rapid development of electrical power systems,ensuring the accuracy and reliability of power transmis-sion has become particularly crucial.The secondary cable line calibrator for current transformers(CT)plays an essential role in calibrating electrical power systems.It is not only related to the safe operation of the system but also directly im-pacts the accuracy of energy metering.This study aims to design and analyze an efficient CT secondary cable line calibra-tor to explore its application effects in the power system.By thoroughly analyzing the characteristics of CT secondary ca-ble lines and the design requirements of the calibrator,this paper proposes an innovative design scheme for the calibrator.This device demonstrates significant effects in enhancing the accuracy and stability of power system calibration,providing robust technical support for the optimization and upgrade of the power system.This research not only offers a theoretical basis and practical guidance for the design and application of CT secondary cable line calibrators but also contributes new ideas and methods for the precise calibration and efficient management of the power system.
文摘Aim: Measurement of B-type natriuretic peptide (BNP) is widely used as a diagnostic and risk assessment tool for cardiovascular disease. Recent studies have demonstrated that BNP-32 and its precursor proBNP circulate in the blood stream, and that most commercial BNP immunoassays measure both forms. However, recombinant or synthetic BNP-32 is used as the standard for those BNP immunoassays. This gap between clinical samples and the standard might be a potential source of variation in BNP measurements among assays. The purpose of this study is to validate a more suitable calibrator for BNP immunoassays. Methods: External BNP calibrators containing both BNP-32 and glycosylated proBNP were prepared at two concentration levels. Target BNP concentrations of the low and high levels were 40 and 160 pg/mL, respectively. And to reflect clinical samples, the molar ratios of BNP-32 to glycosylated proBNP in these concentration levels were adjusted to 50:50 and 25:75, respectively. BNP concentrations of plasma samples along with the external BNP calibrators were measured at two commercial labs and using an automated analyzer MI02 Shionogi®BNP (MI02). These samples and the calibrators were also measured using an immunoradiometric assay (IRMA) as a standard assay procedure. Concentrations of the plasma samples measured at the labs or using the MI02 were adjusted according to a comparison of the measured concentrations of the external BNP calibrators with the IRMA. Results: After measured concentrations of the plasma samples were adjusted using the external BNP calibrators, the correlation between each measurement and the IRMA was improved. The range of the slopes according to Passing-Bablok regression analysis narrowed from 0.628 - 0.955 to 0.911 - 1.005. Conclusions: Our data suggests that a mixture of BNP-32 and glycosylated proBNP at different ratios by concentration level is suitable for calibration to minimize variations in BNP measurements among immunoassays.
文摘Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrator for the famous 4-20 mA electrical signaling scheme. The loop calibrator generates a linear current signal from 4 to 20 mA over a 250 ? typical process instrument load for calibration. The realization of the loop calibrator relies on a voltage-to-current converter to build a constant current source. The voltage controlled constant current source is built from discrete components and an op-amp to keep the cost low. Results from simulations and the prototype demonstrate the performance of the 4-20 mA loop calibrator which utilizes a greatly reduced number of components. The cost of these components is approximately 34% of the least expensive calibrator sampled, though other production costs are not included. This conclusion reinforces the fact that loop calibrators can be cheaper.
文摘Due to the complex erection environment of various types of automatic stations,the provincial meteorological inspection department is difficult to carry out this work in terms of equipment or staffing. For this reason,a portable temperature sensor calibrator was developed,and it uses semiconductor refrigeration technology to increase and decrease temperature quickly. It uses an intelligent PID temperature controller as a control device to provide a stable temperature environment; it is small,light and easy to operate,and it provides technical support for the calibration of temperature sensors. The structure and working principle of this equipment were analyzed,and its performance was tested. All the indicators could meet the requirements of field calibration. The calibrator will provide a strong guarantee for the reliability of temperature data obtained at automatic meteorological stations.
基金supported by Natural Science Foundation of Jilin Province(20210101468JC)Chinese Academy of Sciences and Local Government Cooperation Project(2023SYHZ0027,23SH04)National Natural Science Foundation of China(12273063&12203078)。
文摘Observatories typically deploy all-sky cameras for monitoring cloud cover and weather conditions.However,many of these cameras lack scientific-grade sensors,r.esulting in limited photometric precision,which makes calculating the sky area visibility distribution via extinction measurement challenging.To address this issue,we propose the Photometry-Free Sky Area Visibility Estimation(PFSAVE)method.This method uses the standard magnitude of the faintest star observed within a given sky area to estimate visibility.By employing a pertransformation refitting optimization strategy,we achieve a high-precision coordinate transformation model with an accuracy of 0.42 pixels.Using the results of HEALPix segmentation is also introduced to achieve high spatial resolution.Comprehensive analysis based on real allsky images demonstrates that our method exhibits higher accuracy than the extinction-based method.Our method supports both manual and robotic dynamic scheduling,especially under partially cloudy conditions.
文摘High-precision magnetic field measurements are crucial for understanding Earth’s internal structure,space environment,and dynamic geomagnetic variations.Data from the Fluxgate Magnetometer (FGM) on the Macao Science Satellite-1A (MSS-1A),added to data from other space-based magnetometers,should increase significantly the ability of scientists to observe changes in Earth’s magnetic field over time and space.Additionally,the MSS-1A’s FGM is intended to help identify magnetic disturbances affecting the spacecraft itself.This report focuses on the in-flight calibration of the MSS-1 FGM.A scalar calibration,independent of geomagnetic field models,was performed to correct offsets,sensitivities,and misalignment angles of the FGM.Using seven months of data,we find that the in-flight calibration parameters show good stability.We determined Euler angles describing the rotational relationship between the FGM and the Advanced Stellar Compass (ASC) coordinate system using two approaches:calibration with the CHAOS-7 geomagnetic field model,and simultaneous estimation of Euler angles and Gaussian spherical harmonic coefficients through self-consistent modeling.The accuracy of Euler angles describing the rotation was better than 18 arcsec.The calibrated FGM data exhibit good agreement with the calibrated data of the Vector Field Magnetometer (VFM),which is the primary vector magnetometer of the satellite.These calibration efforts have significantly improved the accuracy of the FGM measurements,which are now providing reliable data for geomagnetic field studies that promise to advance our understanding of the Earth’s magnetic environment.
文摘1.A.Mertha,“‘Stressing Out’:Cadre Calibration and Affective Proximity to the CCP in Reform-Era China”,The China Quarterly,Vol.229,2017,pp.64-85.2.B.L.McCormick,“Book Review of‘The Chinese Communist Party's Capacity to Rule:Ideology,Legitimacy and Party Cohesion’”,The China Journal,Vol.77,2017,pp.161-163.
基金Support by Sichuan Science and Technology Program[2023YFSY0026,2023YFH0004].
文摘Accurate calibration of surgical instruments and ultrasound probes is essential for achieving high precision in image guided minimally invasive procedures.However,existing methods typically treat the calibration of the needle tip and the ultrasound probe as two independent processes,lacking an integrated calibration mechanism,which often leads to cumulative errors and reduced spatial consistency.To address this challenge,we propose a joint calibration model that unifies the calibration of the surgical needle tip and the ultrasound probe within a single coordinate system.The method formulates the calibration process through a series of mathematical models and coordinate transformation models and employs a gradient descent based optimization to refine the parameters of these models.By establishing and iteratively optimizing a template coordinate system through modeling of constrained spherical motion,the proposed joint calibration model achieves submillimeter accuracy in needle tip localization.Building upon this,an N line based calibration model is developed to determine the spatial relationship between the probe and the ultrasound image plane,resulting in an average pixel deviation of only 1.2373 mm.Experimental results confirm that this unified modeling approach effectively overcomes the limitations of separate calibration schemes,significantly enhancing both precision and robustness,and providing a reliable computational model for surgical navigation systems that require high spatial accuracy without relying on ionizing radiation.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFC2201001)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2019B030302001)+1 种基金the National Natural Science Foundation of China(Grant Nos.12105373,12105374,and 11927812)the Science and Technology Research Project of Jiangxi Provincial Department of Education(Grant No.GJJ2402105).
文摘Accurate thrust assessment is crucial for characterizing the performance of micro-thrusters.This paper presents a comprehensive evaluation of the thrust generated by a needle-type indium field emission electric propulsion(In-FEEP)micro-thruster using three methods based on a pendulum:direct thrust measurement,indirect plume momentum transfer and beam current diagnostics.The experimental setup utilized capacitive displacement sensors for force detection and a voice coil motor as a feedback actuator,achieving a resolution better than 0.1μN.Key performance factors such as ionization and plume divergence of ejected charged particles were also examined.The study reveals that the high applied voltage induces significant electrostatic interference,becoming the dominant source of error in direct thrust measurements.Beam current diagnostics and indirect plume momentum measurements were conducted simultaneously,showing strong agreement within a deviation of less than 0.2N across the operational thrust range.The results from all three methods are consistent within the error margins,verifying the reliability of the indirect measurement approach and the theoretical thrust model based on the electrical parameters of In-FEEP.
文摘To enhance direction of arrival(DOA)estimation accuracy,this paper proposes a low-cost method for calibrating farfield steering vectors of large aperture millimeter wave radar(mmWR).To this end,we first derive the steering vectors with amplitude and phase errors,assuming that mmWR works in the time-sharing mode.Then,approximate relationship between the near-field calibration steering vector and the far-field calibration steering vector is analyzed,which is used to accomplish the mapping between the two of them.Finally,simulation results verify that the proposed method can effectively improve the angle measurement accuracy of mmWR with existing amplitude and phase errors.
文摘A recent single-center retrospective study proposed novel combinations of hematological parameters and scoring systems for predicting severe acute pancre-atitis.While these combinations showed promising predictive performance,several limitations warrant consideration,including the lack of calibration,the absence of key inflammatory markers such as procalcitonin,and practical challenges in integrating these models into routine clinical workflows.To improve predictive accuracy and clinical applicability,prospective validation and the inclusion of additional variables are recommended.
基金supported by the National Natural Science Foundation of China(42276199).
文摘In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension Kalman filter is constructed to reduce impact brought by turntable.Then,a biaxial rotation path is designed based on the accelerometer output model,including orthogonal 22 positions and tilt 12 positions,which enhances gravity excitation on nonlinear coefficients of accelerometer.Finally,sampling is carried out for calibration and further experiments.The results of static inertial navigation experiments lasting 4000 s show that compared with the traditional method,the proposed method reduces the position error by about 390 m.
文摘Radiation doses to patients in diagnostics and interventional radiology need to be optimized to comply with the principles of radiation protection in medical practice. This involves using specific detectors with respective diagnostic beams to carry out quality control/quality assurance tests needed to optimize patient doses in the hospital. Semiconductor detectors are used in dosimetry to verify the equipment performance and dose to patients. This work aims to assess the performance, energy dependence, and response of five commercially available semiconductor detectors in RQR, RQR-M, RQA, and RQT at Secondary Standard Dosimetry for clinical applications. The diagnostic beams were generated using Exradin A4 reference ion chamber and PTW electrometer. The ambient temperature and pressure were noted for KTP correction. The detectors designed for RQR showed good performance in RQT beams and vice versa. The detectors designed for RQR-M displayed high energy dependency in other diagnostic beams. The type of diagnostic beam quality determines the response of semiconductor detectors. Therefore, a detector should be calibrated according to the beam qualities to be measured.
基金Yancheng Science and Technology Bureau(YCBK2023027)。
文摘EMC anechoic chamber is used for radiation emission and radiation immunity test,and the wireless performance of products needs to be tested in OTA anechoic chamber.With more and more electronic and electrical equipment with wireless communication function,the rapid construction of a compatible OTA test system in the existing EMC anechoic chamber can save the cost and space of enterprises and third-party laboratories that already have EMC anechoic chamber.In this paper,the OTA test system is built in the existing EMC anechoic room,the ripple calibration test is carried out according to the OTA standard,the TRP and TIS tests are carried out on two test samples with different wireless communication standards,and the test samples are taken to the OTA anechoic room for a comparison test.The comparison between the ripple calibration data and the OTA test data showed that the EMC anechoic chamber could perform OTA test without affecting the original test ability.The data results provide a basis for the implementation of EMC anechoic chamber compatibility upgrade OTA test,and provide reference for further optimization of the compatible test system,reduction of test differences,and the design of anechoic chamber integrating two test functions.
文摘BACKGROUND The EuroSCORE II is a globally accepted tool for predicting mortality in patients undergoing cardiac surgery.However,the discriminative ability of this tool in non-European populations may be inadequate,limiting its use in other regions.AIM To evaluate the performance of EuroSCORE II in patients undergoing coronary artery bypass graft(CABG)surgery at a hospital in Bogotá,Colombia.METHODS An observational,analytical study of a retrospective cohort was designed.All patients admitted to Hospital Universitario Mayor Méderi who underwent CABG between December 2015 and May 2020 were included.In-hospital mortality was the primary outcome evaluated.Furthermore,the performance of EuroSCORE II was assessed in this population.RESULTS A total of 1009 patients were included[median age 66 years IQR=59-72,78.2%men].The overall in-hospital mortality was 5.5%(n=56).The median mortality predicted using EuroSCORE II was 1.29(IQR=0.92-2.11).Non-ST-segment elevation myocardial infarction was the most common preoperative diagnosis(54.1%),followed by ST-segment elevation myocardial infarction(19.1%)and unstable angina(14.3%).Urgent surgery was performed in 87.3%of the patients(n=881).Mortality rates in each group were as follows:Low risk 6.0%(n=45,observed-to-expected(O/E)ratio,5.6),moderate risk 3.0%(n=5,O/E ratio 1.17),high risk 5.0%(n=4,O/E ratio 0.94),and very high risk 7.6%(n=2,O/E ratio 0.71).The overall O/E ratio was 4.2.The area under the curve of EuroSCORE II was 0.55[95%confidence interval:0.48-0.63]CONCLUSION EuroSCORE II exhibited poor performance in this population owing to its low discriminative ability.This finding may be explained by the fact that the population comprised older individuals with higher ventricular function impairment.Moreover,unlike the population in which this tool was originally developed,most patients were not electively admitted for the surgery.
基金supported in part by the National Key Research and Development Program of China under Grant 2020YFB1804800。
文摘This paper considers the fundamental channel estimation problem for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)system in the presence of multi-cell interference.Specifically,this paper focuses on both channel modelling and receiver design for interference estimation and mitigation.We propose a delay-calibrated block-wise linear model,which extracts the delay of the dominant tap of each interference as a key parameter and approximates the residual channel coefficients by the recently developed blockwise linear model.Based on the delay-calibrated block-wise linear model and the angle-domain channel sparsity,we further conceive a message passing algorithm to solve the channel estimation problem.Numerical results demonstrate the superior performance of the proposed algorithm over the state-of-the-art algorithms.
基金the National Natural Science Foundation of China(No.61927822)。
文摘Traditional calibration method for the digital inclinometer relies on manual inspection,and results in its disadvantages of complicated process,low-efficiency and human errors easy to be introduced.To improve both the calibration accuracy and efficiency of digital inclinometer,an automatic digital inclinometer calibration system was developed in this study,and a new display tube recognition algorithm was proposed.First,a high-precision automatic turntable was taken as the reference to calculate the indication error of the inclinometer.Then,the automatic inclinometer calibration control process and the digital inclinometer zero-setting function were formulated.For display tube recognition,a new display tube recognition algorithm combining threading method and feature extraction method was proposed.Finally,the calibration system was calibrated by photoelectric autocollimator and regular polygon mirror,and the calibration system error and repeatability were calculated via a series of experiments.The experimental results showed that the indication error of the proposed calibration system was less than 4",and the repeatability was 3.9".A digital inclinometer with the resolution of 0.1°was taken as a testing example,within the calibration points'range of[-90°,90°],the repeatability of the testing was 0.085°,and the whole testing process was less than 90 s.The digital inclinometer indication error is mainly introduced by the digital inclinometer resolution according to the uncertainty evaluation.
基金supported by the National Natural Science Foundation of China(NNSFC)(Nos.12375123,12205160,and 12335008)the Natural Science Foundation of Henan Province,China(No.242300421048)the postgraduate research and practice innovation project of Henan Normal University(No.YB202402).
文摘We developed a dedicated data analysis framework for silicon strip detector telescopes(SSDTs)of the Compact Spectrometer for Heavy-IoN Experiments(CSHINE)that addresses the challenges of processing complex signals.The framework integrates advanced algorithms for precise calibration,accurate particle identification,and efficient event reconstruction,aiming to account for critical experimental factors such as charge-sharing effects,multi-hit event resolution,and detector response nonuniformity.Its robust performance was demonstrated through the successful analysis of light-charged particles in the 25 MeV/u^(86)Kr+^(124)Sn experiment conducted at the first Radioactive Ion Beam Line in Lanzhou,allowing for precise extraction of physical observables,including energy,momentum,and particle type.Furthermore,utilizing the reconstructed physical information,such as the number of effective physical events and energy spectra to optimize the track recognition algorithm,the final track recognition efficiencies of approximately 90%were achieved.This framework establishes a valuable reference methodology for SSDT-based detector systems in heavy-ion reaction experiments,thereby significantly enhancing the accuracy and efficiency of data analysis in nuclear physics research.
基金supported by the Australian Coal Industry's Research Program(ACARP)(C29048).
文摘Minor errors in the spoil deposition process,such as placing stronger materials with higher shear strength over weaker ones,can lead to potential dump failure.Irregular deposition and inadequate compaction complicate coal spoil behaviour,neces-sitating a robust methodology for temporal monitoring.This study explores using unmanned aerial vehicles(UAV)equipped with red-green-blue(RGB)sensors for efficient data acquisition.Despite their prevalence,raw UAV data exhibit temporal inconsistency,hindering accurate assessments of changes over time which could be attributed to radiometric errors.To this end,the study introduces an empirical line calibration with invariant targets(ELC-IT),for precise calibration across diverse scenes,particularly in the context of UAV imagery used to monitor the evolving nature of spoil dumps.To evaluate the effec-tiveness of this calibration approach,accuracy assessment of an object-based classification is conducted on both calibrated and uncalibrated data.This classification involves several steps:performing segmentation,carrying out feature extraction,and integrating the extracted features and ground truth labels collected over the time period of UAV image capture into machine learning pipelines.Calibrated RGB data exhibit a substantial performance advantage,achieving a 90.7%overall accuracy for spoil pile classification using ensemble(subspace discriminant),representing a noteworthy 7%improvement compared to classifying uncalibrated data.The study highlights the critical role of data calibration in optimising UAV effectiveness for spatio-temporal mine dump monitoring.These findings play a crucial role in informing and refining sustainable management practices within the domain of mine waste management.
基金the Knowledge Innovation Program of Basic Re-search Projects of Shenzhen for their support under Grant No.JCYJ20200109142805928the funding provided by the Basic and Applied Basic Research Foundation of Guangdong Provinæunder Grant No.2021A1515220113partially supported by the Guangzhou Municipal Science and Technology Project under Grant 202102010421.
文摘In clinical environments,the prolonged utilization of polarization equipment can result in theaccumulation of errors over extended periods.The absence of expeditious calibration techniques in clinical practice presents a significant obstacle in preserving the precision and dependability of these instruments.To address this challenge,we propose an innovative research study that presents a comprebersive calibration system specifically designed for the calibration of the backscattering Muellet matrix measurement system,enabling swift online calibration acroes various scenarios.This system employs an external calibration framework for rmal-time adjust-ment of the polarizer's initial angle,oversecing the rotation of PSG and PSA motors through position measurement and control procedures,with light intensity monitored by a camera.By incorporating moment um concepts and the Adam optimization algorithm,we enhance conver-gence speed,mitigate noise,and improve calibration accuracy.Experimental results showcase the exceptional precision,speed,and robustness of oрroposed method,achieving high acсuracy and minimal error,thereby offering a promising solution for maintaining the reliabilit y of polarization equipment in clinical settings.
