In this paper, it is attempted to examine and compare different orientation, one recreational and another more precise, in the performance of two （global positioning system） receivers of forested areas. In doing thi...In this paper, it is attempted to examine and compare different orientation, one recreational and another more precise, in the performance of two （global positioning system） receivers of forested areas. In doing this, a field test on horizontal and vertical positional errors of GPS positioning at different points in the forested area of Taxiarchis-Vrastama University forest was conducted. The two GPS receivers were used to determine the positional accuracy of a selected number of points under tree canopies. Specifically, the precision and accuracy of Garmin＇s GPS positioning at different points were calculated and compared with the corresponding positioning and accuracy of another GPS system, namely the TOPCON GPS. By the calculation of various measures of accuracy and precision suitable for GPS receivers and the use of statistical methods, accuracy between the different receivers differed significantly is shown. Also, regression analysis revealed that the basal area and the number of available satellites are the most important factors for predicting position error.展开更多
In this paper,based on the framework of traditional spectrophotometry,we put forward a novel fast and high-accuracy technique for measuring transmittance spectrum in VIS-NIR wave range,in which its key feature was tha...In this paper,based on the framework of traditional spectrophotometry,we put forward a novel fast and high-accuracy technique for measuring transmittance spectrum in VIS-NIR wave range,in which its key feature was that during the measurement procedure,the output wavelength of the grating monochromator was kept increasing continuously and at the same time,the photoelectric detectors execute d a concurrently continuous data acquisition routine.Initial experiment result showed that the newly proposed technique could shorten the time consumed for measuring the transmittance spectrum down to 50%that of the conventional spectro-photometric method,and a relative error of 0.070%and a repeatability error of 0.042%were generated.Com-pared with the current mostly used techniques(spectrophotometry,methods based on multi-channel spectrometer and strategy using Fourier transform spectrometer)for obtaining transmittance spectrum in VIS-NIR,the new strategy has at all once the following advantages.Firstly the measuring speed could be greatly quicken,and fast measurement of transmittance spectrum in VIS-NIR is therefore promising,which would find wide application in dynamic environment.Secondly high measuring accuracy(0.1%~0.3%)is available,and finally the measuring system has high mechanical stability because the motor of the grating monochromator is rotating continuously during the measurement.展开更多
The main reasons for the occurrence of temperature error and perspective directions of decreasing of its value are presented by improving the device design based on the phenomenon of surface plasmon resonance (SPR) an...The main reasons for the occurrence of temperature error and perspective directions of decreasing of its value are presented by improving the device design based on the phenomenon of surface plasmon resonance (SPR) and numerical methods of processing the results of measurements by this device. The most essential influence on changes in results of measurements can be rendered by temperature changes in the analyte refractive index. It is shown that the application of the integrated temperature stabilization of the device with the test substance, and numerical processing of the measurement results for compensation of temperature changes of the test substance and the use of film heaters it is possible to reduce the measurement error of the refractive index of the analyte at least 30 times from 2.4 × 10-4 to 7.6 × 10-6.展开更多
The lattice parameter,measured with sufficient accuracy,can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials.We propose an iterative method for obtaining more...The lattice parameter,measured with sufficient accuracy,can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials.We propose an iterative method for obtaining more precise lattice parameters using the interaction points for the pseudo-Kossel pattern obtained from laser-induced X-ray diffraction(XRD).This method has been validated by the analysis of an XRD experiment conducted on iron single crystals.Furthermore,the method was used to calculate the compression ratio and rotated angle of an LiF sample under high pressure loading.This technique provides a robust tool for in-situ characterization of structural changes in single crystals under extreme conditions.It has significant implications for studying the equation of state and phase transitions.展开更多
Live line measurement methods can reduce the loss of power outages and eliminate interference. There are three live line measurement methods including integral method, differential method and algebraic method. A simul...Live line measurement methods can reduce the loss of power outages and eliminate interference. There are three live line measurement methods including integral method, differential method and algebraic method. A simulation model of?two coupled parallel transmission lines spanning on the same towers is built in PSCAD and the calculation errors of these three methods are compared with different sampling frequencies by using of Matlab. The effect of harmonic on calculation is also involved. The simulation results indicate that harmonic has the least effect on the algebraic method which provides stable result and small error.展开更多
A lower bound to errors of measuring object position is constructed as a function of parameters of a monocular computer vision system (CVS) as well as of observation conditions and a shape of an observed marker. This ...A lower bound to errors of measuring object position is constructed as a function of parameters of a monocular computer vision system (CVS) as well as of observation conditions and a shape of an observed marker. This bound justifies the specification of the CVS parameters and allows us to formulate constraints for an object trajectory based on required measurement accuracy. For making the measurement, the boundaries of marker image are used.展开更多
The practical value of high-precision models of the studied physical phenomena and technological processes is a decisive factor in science and technology. Currently, numerous methods and criteria for optimizing models...The practical value of high-precision models of the studied physical phenomena and technological processes is a decisive factor in science and technology. Currently, numerous methods and criteria for optimizing models have been proposed. However, the classification of measurement uncertainties due to the number of variables taken into account and their qualitative choice is still not given sufficient attention. The goal is to develop a new criterion suitable for any groups of experimental data obtained as a result of applying various measurement methods. Using the “information-theoretic method”, we propose two procedures for analyzing experimental results using a quantitative indicator to calculate the relative uncertainty of the measurement model, which, in turn, determines the legitimacy of the declared value of a physical constant. The presented procedure is used to analyze the results of measurements of the Boltzmann constant, Planck constant, Hubble constant and gravitational constant.展开更多
The CNC machine tool is the fundamental equipment of the manufacturing industry,particularly in sectors where achieving high levels of accuracy is crucial.Geometric accuracy design is an important step in machine tool...The CNC machine tool is the fundamental equipment of the manufacturing industry,particularly in sectors where achieving high levels of accuracy is crucial.Geometric accuracy design is an important step in machine tool design and plays an essential role in determining the machining accuracy of the workpiece.Researchers have extensively studied methods to model,extract,optimize,and measure the geometric errors that affect the geometric accuracy of machine tools.This paper provides a comprehensive review of the state-of-the-art approaches and an overview of the latest research progress associated with geometric accuracy design in CNC machine tools.This paper explores the interrelated aspects of CNC machine tool accuracy design:modeling,analysis and optimization.Accuracy analysis,which includes geometric error modeling and sensitivity analysis,determines a machine tool’s output accuracy through its volumetric error model,given the known accuracy of its individual components.Conversely,accuracy allocation designs the accuracy of the machine tool components according to given output accuracy requirements to achieve optimization between the objectives of manufacturing cost,quality,reliability,and environmental impact.In addition to discussing design factors and evaluation methods,this paper outlines methods for verifying the accuracy of design results,aiming to provide a practical basis for ensuring that the designed accuracy is achieved.Finally,the challenges and future research directions in geometric accuracy design are highlighted.展开更多
Accuracy allocation is crucial in the accuracy design of machining tools.Current accuracy allocation methods primarily focus on positional deviation,with little consideration for tool direction deviation.To address th...Accuracy allocation is crucial in the accuracy design of machining tools.Current accuracy allocation methods primarily focus on positional deviation,with little consideration for tool direction deviation.To address this issue,we propose a geometric error cost sensitivity-based accuracy allocation method for five-axis machine tools.A geometric error model consisting of 4l error components is constructed based on homogeneous transformation matrices.Volumetric points with positional and tool direction deviations are randomly sampled to evaluate the accuracy of the machine tool.The sensitivity of each error component at these sampling points is analyzed using the Sobol method.To balance the needs of geometric precision and manufacturing cost,a geometric error cost sensitivity function is developed to estimate the required cost.By allocating error components affecting tool direction deviation first and the remaining components second,this allocation scheme ensures that both deviations meet the requirements.We also perform numerical simulation of a BC-type(B-axis and C-axis type)five-axis machine tool to validate the method.The results show that the new allocation scheme reduces the total geometric error cost by 27.8%compared to a uniform allocation scheme,and yields the same positional and tool direction machining accuracies.展开更多
The accuracy of thermal analysis measurements is critical to analyze material properties correctly,making the improvement of measurement precision and proper uncertainty analysis of test results absolutely essential.A...The accuracy of thermal analysis measurements is critical to analyze material properties correctly,making the improvement of measurement precision and proper uncertainty analysis of test results absolutely essential.As a primary thermal analysis instrument,the simultaneous thermal analyzer(STA)has unique advantages,which combines the functionalities of thermogravimetric(TG)analyzersand differential scanning calorimeters(DSC).However,the absence of standard quality control procedures has resulted in poor measurement reproducibility,low accuracy,and inadequate traceability of analytical results.This study utilized a multi-point temperature calibration method based on national certified reference materials to reduce instrument temperature indication errors.On this basis,we innovatively established a comprehensive quality control system encompassing laboratory environmental control,standard method selection,instrument performance verification,reference material traceability,and uncertainty analysis,thereby achieving standardized operational procedures for thermal analysis measurement.Taking the"determination of initial melting temperature of unknown substances"as a representative case study,a component resolution model for thermal analysis test uncertainty was developed.Through systematic analysis of both the reference material-introduced component and measurement repeatability component,complete traceability of test results was achieved.This approach ensures data validity and enhances the accuracy of test results.This provides crucial technical support and practical reference for the standardization of thermal analysis measurement procedure and assessment of result reliability.展开更多
BACKGROUND The accuracy of blind intra-articular injections in the shoulder is rather low.Inaccurate injections tend to lead to poorer treatment outcomes.The“Delaware posterior bone touch technique”has shown higher ...BACKGROUND The accuracy of blind intra-articular injections in the shoulder is rather low.Inaccurate injections tend to lead to poorer treatment outcomes.The“Delaware posterior bone touch technique”has shown higher accuracy in young,slender,healthy volunteers than the classical“Cyriax technique”.AIM To investigate whether the Delaware technique would also be more accurate in older patients with capsulitis.METHODS We analyzed the files of 100 consecutive patients with capsulitis who were treated with an intra-articular injection containing a mixture of triamcinolone,lidocaine,and air.After the injection,the shoulder was moved to determine whether a squishing sound could be produced.The squishing sound was interpreted as an accurate injection.The scores with the new Delaware technique were compared against those with the Cyriax technique in a previous study.RESULTS Squishing was heard after 87%of the injections.This was 13%(10%points)more than the 77%in the previous study(P=0.004).CONCLUSION The Delaware technique was significantly more accurate than the Cyriax technique also in middle aged patients with capsulitis.We hypothesize that the difference is caused by a lower risk that a part of the opening of the needle is still outside the capsule.展开更多
The travel-time corrections for the primary seismic phases of 72 stations in the Guangdong seismic network,relative to the 1D South China travel-time model,were determined using joint hypocentral determination(JHD)and...The travel-time corrections for the primary seismic phases of 72 stations in the Guangdong seismic network,relative to the 1D South China travel-time model,were determined using joint hypocentral determination(JHD)and statistical analysis methods.The travel-time corrections for the Pg phase of 72 stations range between-0.25 s and 0.14 s,while the corrections for the Sg phase range between 0.27 s and 0.35 s,and those for the Pn phase are between-0.86 s and 0.07 s.The spatial distribution of travel-time corrections for Pg,Sg,and Pn phases of 72 stations correlates well with the geological structure in this region.This indicates that the travel-time corrections for Pg and Sg phases are mainly caused by the discrepancy between the actual crustal velocity structure beneath the stations and the 1D South China travel-time model.These corrections empirically compensate for systematic travel-time errors arising from such discrepancies.The primary factor contributing to the travel-time corrections for the Pn phase is the Moho undulations or tilt.These corrections are intended to compensate for systematic errors in travel time caused by variations in the actual Moho.By integrating the obtained travel-time corrections into the HYPO-SAT location algorithm,test results showed an obvious improvement in location accuracy and origin time precision for explosion events.The variation of horizontal distance between repeating earthquake pairs has also improved,with 86%of the repeating earthquake pair spacing being more accurately estimated after correction.This suggests the crucial significance of travel-time correction in earthquake location,and the consideration of travel-time correction exerts a notable impact on enhancing earthquake location accuracy.展开更多
Objective:To analyze the significance of high-frequency ultrasound in differentiating benign and malignant breast micronodules.Methods:Eighty-five patients with breast micronodules admitted for diagnosis between Octob...Objective:To analyze the significance of high-frequency ultrasound in differentiating benign and malignant breast micronodules.Methods:Eighty-five patients with breast micronodules admitted for diagnosis between October 2022 and October 2024 were selected for high-frequency ultrasound diagnosis.The diagnostic efficacy of high-frequency ultrasound was evaluated by comparing it with the results of surgical pathology.Results:High-frequency ultrasound detected 50 benign nodules,primarily breast fibroadenomas,and 35 malignant nodules,mainly breast ductal carcinoma in situ.Based on surgical pathology results,the diagnostic accuracy of high-frequency ultrasound was 96.47%,specificity was 97.96%,and sensitivity was 94.44%.In high-frequency ultrasound diagnosis,the proportion of grade III and IV blood flow in malignant nodules was higher than that in benign nodules,while the proportion of regular shape and clear margins was lower.The proportion of microcalcifications and posterior echo attenuation was higher in malignant nodules,and the resistance index(RI)and peak blood flow velocity were lower than those in benign nodules(P<0.05).Conclusion:High-frequency ultrasound can effectively differentiate benign and malignant breast micronodules,determine specific nodule types,and exhibits high diagnostic accuracy and sensitivity.Additionally,benign and malignant nodules can be differentiated based on the grading of blood flow signals,sonographic features,and blood flow velocity,providing reasonable guidance for subsequent treatment plans.展开更多
Artificial intelligence(AI)is rapidly transforming radiology and computed tomography(CT)imaging by enabling automated image analysis,improved diagnostic accuracy,and clinical decision-support.We performed a systematic...Artificial intelligence(AI)is rapidly transforming radiology and computed tomography(CT)imaging by enabling automated image analysis,improved diagnostic accuracy,and clinical decision-support.We performed a systematic review of peerreviewed studies published between January 1,2010 and March 31,2025 to quantify reported gains in diagnostic performance and workflow efficiency,to evaluate clinical decision-support benefits and risks,and to identify integration priorities.We searched PubMed,IEEE Xplore,Scopus,ScienceDirect,and Google Scholar and screened 128 records;26 studies met the inclusion criteria.Extracted data included study design,AI architecture,sample size,and quantitative performance metrics;study quality was assessed using Newcastle-Ottawa Scales(NOS),Cochrane RoB 2,or AMSTAR 2 as appropriate.Across included studies,AI applications in CT showed consistent improvements in sensitivity,specificity,and time-to-diagnosis in specific tasks(notably lung-nodule detection and intracranial hemorrhage triage),with reported detection-rate increases up to~20%and reduced turnaround times in several real-world implementations.Barriers include dataset bias,limited external validation,interpretability(“black-box”)concerns,workflow integration challenges,and evolving regulatory issues.Economic analyses suggest potentially favorable return on investment(ROI)in high-volume settings but are sensitive to licensing and infrastructure costs.To realize AI's benefits in CT imaging,rigorous multi-center validation,transparent reporting,humancentered workflow design,and post-deployment surveillance are essential.展开更多
Objective:To explore nursing measures for elderly patients with chronic obstructive pulmonary disease(COPD)and analyze the effect of continuous nursing pathways on improving the accuracy of aerosol use.Methods:From Ap...Objective:To explore nursing measures for elderly patients with chronic obstructive pulmonary disease(COPD)and analyze the effect of continuous nursing pathways on improving the accuracy of aerosol use.Methods:From April 2023 to April 2024,76 elderly COPD patients admitted to our hospital were randomly selected for nursing research.They were divided into two groups using a computer double-blind method,with 38 patients in each group.The control group received routine nursing,while the observation group applied the continuous nursing pathway.The nursing effects of the two groups were investigated and compared,including(1)aerosol accuracy;(2)cardiopulmonary function;(3)subjective well-being and self-care ability;(4)quality of life;and(5)nursing satisfaction.Results:Compared with the control group,the observation group had a significantly higher accuracy rate of aerosol use(P<0.05).Before nursing,there were no significant differences in cardiopulmonary function indicators,MUNSH scores,and ESCA scores between the two groups(P>0.05).After nursing,the patient's cardiopulmonary function improved significantly,and their subjective well-being and self-care ability increased.The observation group was significantly better than the control group in all the above indicators(P<0.05).The quality of life scores of the observation group were significantly higher than those of the control group(P<0.05).Conclusion:In the nursing of elderly patients with chronic obstructive pulmonary disease,the application of the continuous nursing pathway can effectively improve the accuracy of aerosol use and improve patients'cardiopulmonary function.展开更多
This brief presents a cryogenic voltage reference circuit designed to operate effectively across a wide temperature range from 30 to 300 K.A key feature of the proposed design is utilizing a current subtraction techni...This brief presents a cryogenic voltage reference circuit designed to operate effectively across a wide temperature range from 30 to 300 K.A key feature of the proposed design is utilizing a current subtraction technique for temperature compensation of the reference current,avoiding the deployment of bipolar transistors to reduce area and power consumption.Implemented with a 0.18-μm CMOS process,the circuit achieves a temperature coefficient(TC)of 67.5 ppm/K,which was not achieved in previous works.The design can also attain a power supply rejection(PSR)of 58 d B at 10 k Hz.Meanwhile,the average reference voltage is 1.2 V within a 1.6%3σ-accuracy spread.Additionally,the design is characterized by a minimal power dissipation of 1μW at 30 K and a compact chip area of 0.0035 mm~2.展开更多
Changes in lake levels, as an indicator of climate change, are crucial for understanding water resources.Satellite altimetry has proven to be an effective technique for monitoring water level changes in inland lakes. ...Changes in lake levels, as an indicator of climate change, are crucial for understanding water resources.Satellite altimetry has proven to be an effective technique for monitoring water level changes in inland lakes. However, high-altitude and high-latitude lakes undergo seasonal freezing and melting, affecting satellite altimetry accuracy. This paper evaluates the accuracy of lake level height observations by the CryoSat-2, which uses synthetic aperture radar(SAR) across seasons. First, we used lake boundary based on optical remote sensing data to extract the footprints of CryoSat-2 that fall on Namco and Zhari Namco.After elevation conversion and anomaly identification, we obtained the time series of lake levels. These data were compared and verified against lake levels from in-situ measurements to assess the accuracy of CryoSat-2. The results show that CryoSat-2 can monitor lake level height with an accuracy of about 10-13 cm. The correlation coefficient between CryoSat-2 observations and in-situ measurements over Namco is 0.80(p < 0.01), with a Root Mean Square Error(RMSE) of 13 cm. For Zhari Namco, the correlation coefficient is 0.91, with an RMSE of 10 cm, indicating a better match. At the seasonal scale, the seasonal correlation coefficients between CryoSat-2 and in-situ measurement in Namco are 0.47(spring),0.79(summer), and 0.91(fall) with no observations available for winter. The lower correlation in spring may be due to incomplete ice melting. For Zhari Namco, the seasonal correlation coefficients are 0.89(spring), 0.93(summer), 0.89(fall), and 0.87(winter). The results show that CryoSat-2 accuracy is higher in summer and fall, while slightly lower in spring and winter, indicating that ice formation affects accuracy. Even during winter, the altimetry results do not significantly exceed the in-situ lake water level observations.展开更多
Position-sensitive detector(PSD)is widely used in precision measurement fields such as flatness detection,auto-collimator systems,and degrees of freedom testing.However,due to factors such as uneven surface resistance...Position-sensitive detector(PSD)is widely used in precision measurement fields such as flatness detection,auto-collimator systems,and degrees of freedom testing.However,due to factors such as uneven surface resistance and differences in electrode structures,the nonlinearity of PSD becomes increasingly severe as the photosensitive surface moves from the center toward the edges of the four electrodes.To address this issue,a PSD nonlinearity correction algorithm is proposed.The algorithm utilizes the particle swarm optimization(PSO)algorithm to determine the optimal weights and thresholds,providing better initial parameters for the back propagation(BP)neural network.The BP neural network then iterates continuously until the error conditions are met,completing the correction process.Furthermore,a PSD nonlinearity correction system was developed,and the influence of different spot sizes on PSD positioning accuracy was simulated based on the current equation under the Gaussian spot model.This validated the robustness of the correction algorithm under varying spot sizes.The results demonstrate that the overall optimized error is reduced by 84.51%,and for spot sizes smaller than 1 mm,the error reduction exceeds 93.89%.This method not only meets the measurement accuracy requirements but also extends the measurement range of PSD.展开更多
In this study,we investigate the extent to which sustainability disclosures in the narrative sections of European banks’annual reports improve analysts’forecasting accuracy.We capture sustainability disclosures with...In this study,we investigate the extent to which sustainability disclosures in the narrative sections of European banks’annual reports improve analysts’forecasting accuracy.We capture sustainability disclosures with a machine learning approach and use forecast errors as a proxy for analysts’forecast accuracy.Our results suggest that sustainability disclosures significantly improve analysts’forecasting accuracy by reducing forecast errors.In a further analysis,we also find that the introduction of Directive 2014/95/European Union is associated with increased disclosure content,which reduces forecast error.Collectively,our results suggest that sustainability disclosures improve forecast accuracy,and the introduction of the new EU directive strengthens this improvement.These results hold after several robustness tests.Our findings have important implications for market participants and policymakers.展开更多
文摘In this paper, it is attempted to examine and compare different orientation, one recreational and another more precise, in the performance of two （global positioning system） receivers of forested areas. In doing this, a field test on horizontal and vertical positional errors of GPS positioning at different points in the forested area of Taxiarchis-Vrastama University forest was conducted. The two GPS receivers were used to determine the positional accuracy of a selected number of points under tree canopies. Specifically, the precision and accuracy of Garmin＇s GPS positioning at different points were calculated and compared with the corresponding positioning and accuracy of another GPS system, namely the TOPCON GPS. By the calculation of various measures of accuracy and precision suitable for GPS receivers and the use of statistical methods, accuracy between the different receivers differed significantly is shown. Also, regression analysis revealed that the basal area and the number of available satellites are the most important factors for predicting position error.
基金the National Natural Science Foundation of China(11602280,617905246)the scientific equipment developing project of the Chinese academy of sciences(28201631231100101)
文摘In this paper,based on the framework of traditional spectrophotometry,we put forward a novel fast and high-accuracy technique for measuring transmittance spectrum in VIS-NIR wave range,in which its key feature was that during the measurement procedure,the output wavelength of the grating monochromator was kept increasing continuously and at the same time,the photoelectric detectors execute d a concurrently continuous data acquisition routine.Initial experiment result showed that the newly proposed technique could shorten the time consumed for measuring the transmittance spectrum down to 50%that of the conventional spectro-photometric method,and a relative error of 0.070%and a repeatability error of 0.042%were generated.Com-pared with the current mostly used techniques(spectrophotometry,methods based on multi-channel spectrometer and strategy using Fourier transform spectrometer)for obtaining transmittance spectrum in VIS-NIR,the new strategy has at all once the following advantages.Firstly the measuring speed could be greatly quicken,and fast measurement of transmittance spectrum in VIS-NIR is therefore promising,which would find wide application in dynamic environment.Secondly high measuring accuracy(0.1%~0.3%)is available,and finally the measuring system has high mechanical stability because the motor of the grating monochromator is rotating continuously during the measurement.
文摘The main reasons for the occurrence of temperature error and perspective directions of decreasing of its value are presented by improving the device design based on the phenomenon of surface plasmon resonance (SPR) and numerical methods of processing the results of measurements by this device. The most essential influence on changes in results of measurements can be rendered by temperature changes in the analyte refractive index. It is shown that the application of the integrated temperature stabilization of the device with the test substance, and numerical processing of the measurement results for compensation of temperature changes of the test substance and the use of film heaters it is possible to reduce the measurement error of the refractive index of the analyte at least 30 times from 2.4 × 10-4 to 7.6 × 10-6.
基金National Natural Science Foundation of China(12102410)Fund of National Key Laboratory of Shock Wave and Detonation Physics(JCKYS2022212005)。
文摘The lattice parameter,measured with sufficient accuracy,can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials.We propose an iterative method for obtaining more precise lattice parameters using the interaction points for the pseudo-Kossel pattern obtained from laser-induced X-ray diffraction(XRD).This method has been validated by the analysis of an XRD experiment conducted on iron single crystals.Furthermore,the method was used to calculate the compression ratio and rotated angle of an LiF sample under high pressure loading.This technique provides a robust tool for in-situ characterization of structural changes in single crystals under extreme conditions.It has significant implications for studying the equation of state and phase transitions.
文摘Live line measurement methods can reduce the loss of power outages and eliminate interference. There are three live line measurement methods including integral method, differential method and algebraic method. A simulation model of?two coupled parallel transmission lines spanning on the same towers is built in PSCAD and the calculation errors of these three methods are compared with different sampling frequencies by using of Matlab. The effect of harmonic on calculation is also involved. The simulation results indicate that harmonic has the least effect on the algebraic method which provides stable result and small error.
文摘A lower bound to errors of measuring object position is constructed as a function of parameters of a monocular computer vision system (CVS) as well as of observation conditions and a shape of an observed marker. This bound justifies the specification of the CVS parameters and allows us to formulate constraints for an object trajectory based on required measurement accuracy. For making the measurement, the boundaries of marker image are used.
文摘The practical value of high-precision models of the studied physical phenomena and technological processes is a decisive factor in science and technology. Currently, numerous methods and criteria for optimizing models have been proposed. However, the classification of measurement uncertainties due to the number of variables taken into account and their qualitative choice is still not given sufficient attention. The goal is to develop a new criterion suitable for any groups of experimental data obtained as a result of applying various measurement methods. Using the “information-theoretic method”, we propose two procedures for analyzing experimental results using a quantitative indicator to calculate the relative uncertainty of the measurement model, which, in turn, determines the legitimacy of the declared value of a physical constant. The presented procedure is used to analyze the results of measurements of the Boltzmann constant, Planck constant, Hubble constant and gravitational constant.
基金Supported by the National Natural Science Foundation of China(Grant Nos.52375448,52275440).
文摘The CNC machine tool is the fundamental equipment of the manufacturing industry,particularly in sectors where achieving high levels of accuracy is crucial.Geometric accuracy design is an important step in machine tool design and plays an essential role in determining the machining accuracy of the workpiece.Researchers have extensively studied methods to model,extract,optimize,and measure the geometric errors that affect the geometric accuracy of machine tools.This paper provides a comprehensive review of the state-of-the-art approaches and an overview of the latest research progress associated with geometric accuracy design in CNC machine tools.This paper explores the interrelated aspects of CNC machine tool accuracy design:modeling,analysis and optimization.Accuracy analysis,which includes geometric error modeling and sensitivity analysis,determines a machine tool’s output accuracy through its volumetric error model,given the known accuracy of its individual components.Conversely,accuracy allocation designs the accuracy of the machine tool components according to given output accuracy requirements to achieve optimization between the objectives of manufacturing cost,quality,reliability,and environmental impact.In addition to discussing design factors and evaluation methods,this paper outlines methods for verifying the accuracy of design results,aiming to provide a practical basis for ensuring that the designed accuracy is achieved.Finally,the challenges and future research directions in geometric accuracy design are highlighted.
基金supported by the Key R&D Program of Zhejiang Province(Nos.2023C01166 and 2024SJCZX0046)the Zhejiang Provincial Natural Science Foundation of China(Nos.LDT23E05013E05 and LD24E050009)the Natural Science Foundation of Ningbo(No.2021J150),China.
文摘Accuracy allocation is crucial in the accuracy design of machining tools.Current accuracy allocation methods primarily focus on positional deviation,with little consideration for tool direction deviation.To address this issue,we propose a geometric error cost sensitivity-based accuracy allocation method for five-axis machine tools.A geometric error model consisting of 4l error components is constructed based on homogeneous transformation matrices.Volumetric points with positional and tool direction deviations are randomly sampled to evaluate the accuracy of the machine tool.The sensitivity of each error component at these sampling points is analyzed using the Sobol method.To balance the needs of geometric precision and manufacturing cost,a geometric error cost sensitivity function is developed to estimate the required cost.By allocating error components affecting tool direction deviation first and the remaining components second,this allocation scheme ensures that both deviations meet the requirements.We also perform numerical simulation of a BC-type(B-axis and C-axis type)five-axis machine tool to validate the method.The results show that the new allocation scheme reduces the total geometric error cost by 27.8%compared to a uniform allocation scheme,and yields the same positional and tool direction machining accuracies.
文摘The accuracy of thermal analysis measurements is critical to analyze material properties correctly,making the improvement of measurement precision and proper uncertainty analysis of test results absolutely essential.As a primary thermal analysis instrument,the simultaneous thermal analyzer(STA)has unique advantages,which combines the functionalities of thermogravimetric(TG)analyzersand differential scanning calorimeters(DSC).However,the absence of standard quality control procedures has resulted in poor measurement reproducibility,low accuracy,and inadequate traceability of analytical results.This study utilized a multi-point temperature calibration method based on national certified reference materials to reduce instrument temperature indication errors.On this basis,we innovatively established a comprehensive quality control system encompassing laboratory environmental control,standard method selection,instrument performance verification,reference material traceability,and uncertainty analysis,thereby achieving standardized operational procedures for thermal analysis measurement.Taking the"determination of initial melting temperature of unknown substances"as a representative case study,a component resolution model for thermal analysis test uncertainty was developed.Through systematic analysis of both the reference material-introduced component and measurement repeatability component,complete traceability of test results was achieved.This approach ensures data validity and enhances the accuracy of test results.This provides crucial technical support and practical reference for the standardization of thermal analysis measurement procedure and assessment of result reliability.
文摘BACKGROUND The accuracy of blind intra-articular injections in the shoulder is rather low.Inaccurate injections tend to lead to poorer treatment outcomes.The“Delaware posterior bone touch technique”has shown higher accuracy in young,slender,healthy volunteers than the classical“Cyriax technique”.AIM To investigate whether the Delaware technique would also be more accurate in older patients with capsulitis.METHODS We analyzed the files of 100 consecutive patients with capsulitis who were treated with an intra-articular injection containing a mixture of triamcinolone,lidocaine,and air.After the injection,the shoulder was moved to determine whether a squishing sound could be produced.The squishing sound was interpreted as an accurate injection.The scores with the new Delaware technique were compared against those with the Cyriax technique in a previous study.RESULTS Squishing was heard after 87%of the injections.This was 13%(10%points)more than the 77%in the previous study(P=0.004).CONCLUSION The Delaware technique was significantly more accurate than the Cyriax technique also in middle aged patients with capsulitis.We hypothesize that the difference is caused by a lower risk that a part of the opening of the needle is still outside the capsule.
基金supported by the National Key Research and Development Program of China(2023YFC3008605)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021002)the Seismological Research Foundation for Youths of Guangdong Earthquake Agency(Open Funding Project of Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology,China Earthquake Administration)(GDDZY202309)。
文摘The travel-time corrections for the primary seismic phases of 72 stations in the Guangdong seismic network,relative to the 1D South China travel-time model,were determined using joint hypocentral determination(JHD)and statistical analysis methods.The travel-time corrections for the Pg phase of 72 stations range between-0.25 s and 0.14 s,while the corrections for the Sg phase range between 0.27 s and 0.35 s,and those for the Pn phase are between-0.86 s and 0.07 s.The spatial distribution of travel-time corrections for Pg,Sg,and Pn phases of 72 stations correlates well with the geological structure in this region.This indicates that the travel-time corrections for Pg and Sg phases are mainly caused by the discrepancy between the actual crustal velocity structure beneath the stations and the 1D South China travel-time model.These corrections empirically compensate for systematic travel-time errors arising from such discrepancies.The primary factor contributing to the travel-time corrections for the Pn phase is the Moho undulations or tilt.These corrections are intended to compensate for systematic errors in travel time caused by variations in the actual Moho.By integrating the obtained travel-time corrections into the HYPO-SAT location algorithm,test results showed an obvious improvement in location accuracy and origin time precision for explosion events.The variation of horizontal distance between repeating earthquake pairs has also improved,with 86%of the repeating earthquake pair spacing being more accurately estimated after correction.This suggests the crucial significance of travel-time correction in earthquake location,and the consideration of travel-time correction exerts a notable impact on enhancing earthquake location accuracy.
文摘Objective:To analyze the significance of high-frequency ultrasound in differentiating benign and malignant breast micronodules.Methods:Eighty-five patients with breast micronodules admitted for diagnosis between October 2022 and October 2024 were selected for high-frequency ultrasound diagnosis.The diagnostic efficacy of high-frequency ultrasound was evaluated by comparing it with the results of surgical pathology.Results:High-frequency ultrasound detected 50 benign nodules,primarily breast fibroadenomas,and 35 malignant nodules,mainly breast ductal carcinoma in situ.Based on surgical pathology results,the diagnostic accuracy of high-frequency ultrasound was 96.47%,specificity was 97.96%,and sensitivity was 94.44%.In high-frequency ultrasound diagnosis,the proportion of grade III and IV blood flow in malignant nodules was higher than that in benign nodules,while the proportion of regular shape and clear margins was lower.The proportion of microcalcifications and posterior echo attenuation was higher in malignant nodules,and the resistance index(RI)and peak blood flow velocity were lower than those in benign nodules(P<0.05).Conclusion:High-frequency ultrasound can effectively differentiate benign and malignant breast micronodules,determine specific nodule types,and exhibits high diagnostic accuracy and sensitivity.Additionally,benign and malignant nodules can be differentiated based on the grading of blood flow signals,sonographic features,and blood flow velocity,providing reasonable guidance for subsequent treatment plans.
文摘Artificial intelligence(AI)is rapidly transforming radiology and computed tomography(CT)imaging by enabling automated image analysis,improved diagnostic accuracy,and clinical decision-support.We performed a systematic review of peerreviewed studies published between January 1,2010 and March 31,2025 to quantify reported gains in diagnostic performance and workflow efficiency,to evaluate clinical decision-support benefits and risks,and to identify integration priorities.We searched PubMed,IEEE Xplore,Scopus,ScienceDirect,and Google Scholar and screened 128 records;26 studies met the inclusion criteria.Extracted data included study design,AI architecture,sample size,and quantitative performance metrics;study quality was assessed using Newcastle-Ottawa Scales(NOS),Cochrane RoB 2,or AMSTAR 2 as appropriate.Across included studies,AI applications in CT showed consistent improvements in sensitivity,specificity,and time-to-diagnosis in specific tasks(notably lung-nodule detection and intracranial hemorrhage triage),with reported detection-rate increases up to~20%and reduced turnaround times in several real-world implementations.Barriers include dataset bias,limited external validation,interpretability(“black-box”)concerns,workflow integration challenges,and evolving regulatory issues.Economic analyses suggest potentially favorable return on investment(ROI)in high-volume settings but are sensitive to licensing and infrastructure costs.To realize AI's benefits in CT imaging,rigorous multi-center validation,transparent reporting,humancentered workflow design,and post-deployment surveillance are essential.
文摘Objective:To explore nursing measures for elderly patients with chronic obstructive pulmonary disease(COPD)and analyze the effect of continuous nursing pathways on improving the accuracy of aerosol use.Methods:From April 2023 to April 2024,76 elderly COPD patients admitted to our hospital were randomly selected for nursing research.They were divided into two groups using a computer double-blind method,with 38 patients in each group.The control group received routine nursing,while the observation group applied the continuous nursing pathway.The nursing effects of the two groups were investigated and compared,including(1)aerosol accuracy;(2)cardiopulmonary function;(3)subjective well-being and self-care ability;(4)quality of life;and(5)nursing satisfaction.Results:Compared with the control group,the observation group had a significantly higher accuracy rate of aerosol use(P<0.05).Before nursing,there were no significant differences in cardiopulmonary function indicators,MUNSH scores,and ESCA scores between the two groups(P>0.05).After nursing,the patient's cardiopulmonary function improved significantly,and their subjective well-being and self-care ability increased.The observation group was significantly better than the control group in all the above indicators(P<0.05).The quality of life scores of the observation group were significantly higher than those of the control group(P<0.05).Conclusion:In the nursing of elderly patients with chronic obstructive pulmonary disease,the application of the continuous nursing pathway can effectively improve the accuracy of aerosol use and improve patients'cardiopulmonary function.
基金supported in part by the National Key Research and Development Program of China(2021YFA0715503)。
文摘This brief presents a cryogenic voltage reference circuit designed to operate effectively across a wide temperature range from 30 to 300 K.A key feature of the proposed design is utilizing a current subtraction technique for temperature compensation of the reference current,avoiding the deployment of bipolar transistors to reduce area and power consumption.Implemented with a 0.18-μm CMOS process,the circuit achieves a temperature coefficient(TC)of 67.5 ppm/K,which was not achieved in previous works.The design can also attain a power supply rejection(PSR)of 58 d B at 10 k Hz.Meanwhile,the average reference voltage is 1.2 V within a 1.6%3σ-accuracy spread.Additionally,the design is characterized by a minimal power dissipation of 1μW at 30 K and a compact chip area of 0.0035 mm~2.
基金financial supported by National Natural Science Foundation of China (42104010, 42174097, 41974093, and 41774088)the Fundamental Research Funds for the Central Universities
文摘Changes in lake levels, as an indicator of climate change, are crucial for understanding water resources.Satellite altimetry has proven to be an effective technique for monitoring water level changes in inland lakes. However, high-altitude and high-latitude lakes undergo seasonal freezing and melting, affecting satellite altimetry accuracy. This paper evaluates the accuracy of lake level height observations by the CryoSat-2, which uses synthetic aperture radar(SAR) across seasons. First, we used lake boundary based on optical remote sensing data to extract the footprints of CryoSat-2 that fall on Namco and Zhari Namco.After elevation conversion and anomaly identification, we obtained the time series of lake levels. These data were compared and verified against lake levels from in-situ measurements to assess the accuracy of CryoSat-2. The results show that CryoSat-2 can monitor lake level height with an accuracy of about 10-13 cm. The correlation coefficient between CryoSat-2 observations and in-situ measurements over Namco is 0.80(p < 0.01), with a Root Mean Square Error(RMSE) of 13 cm. For Zhari Namco, the correlation coefficient is 0.91, with an RMSE of 10 cm, indicating a better match. At the seasonal scale, the seasonal correlation coefficients between CryoSat-2 and in-situ measurement in Namco are 0.47(spring),0.79(summer), and 0.91(fall) with no observations available for winter. The lower correlation in spring may be due to incomplete ice melting. For Zhari Namco, the seasonal correlation coefficients are 0.89(spring), 0.93(summer), 0.89(fall), and 0.87(winter). The results show that CryoSat-2 accuracy is higher in summer and fall, while slightly lower in spring and winter, indicating that ice formation affects accuracy. Even during winter, the altimetry results do not significantly exceed the in-situ lake water level observations.
基金Supported by the National Natural Science Foundation of China(U1831133)Open Fund of Key Laboratory of Space Active Optoelectronics Technology,Chinese Academy of Sciences(2021ZDKF4)。
文摘Position-sensitive detector(PSD)is widely used in precision measurement fields such as flatness detection,auto-collimator systems,and degrees of freedom testing.However,due to factors such as uneven surface resistance and differences in electrode structures,the nonlinearity of PSD becomes increasingly severe as the photosensitive surface moves from the center toward the edges of the four electrodes.To address this issue,a PSD nonlinearity correction algorithm is proposed.The algorithm utilizes the particle swarm optimization(PSO)algorithm to determine the optimal weights and thresholds,providing better initial parameters for the back propagation(BP)neural network.The BP neural network then iterates continuously until the error conditions are met,completing the correction process.Furthermore,a PSD nonlinearity correction system was developed,and the influence of different spot sizes on PSD positioning accuracy was simulated based on the current equation under the Gaussian spot model.This validated the robustness of the correction algorithm under varying spot sizes.The results demonstrate that the overall optimized error is reduced by 84.51%,and for spot sizes smaller than 1 mm,the error reduction exceeds 93.89%.This method not only meets the measurement accuracy requirements but also extends the measurement range of PSD.
文摘In this study,we investigate the extent to which sustainability disclosures in the narrative sections of European banks’annual reports improve analysts’forecasting accuracy.We capture sustainability disclosures with a machine learning approach and use forecast errors as a proxy for analysts’forecast accuracy.Our results suggest that sustainability disclosures significantly improve analysts’forecasting accuracy by reducing forecast errors.In a further analysis,we also find that the introduction of Directive 2014/95/European Union is associated with increased disclosure content,which reduces forecast error.Collectively,our results suggest that sustainability disclosures improve forecast accuracy,and the introduction of the new EU directive strengthens this improvement.These results hold after several robustness tests.Our findings have important implications for market participants and policymakers.
