In this study,a self-calibrating near-infrared fluorescence probe was designed and synthesized based on the dual-fluorophore strategy utilizing methylene blue and coumarin.The probe utilized methylene blue(emission sp...In this study,a self-calibrating near-infrared fluorescence probe was designed and synthesized based on the dual-fluorophore strategy utilizing methylene blue and coumarin.The probe utilized methylene blue(emission spectrum range:640-740 nm)and coumarin fluorophore(emission spectrum range:440-600 nm)as signal output units,thereby achieving effective spectral separation and highly selective detection of HClO.Under physiological pH conditions,HClO triggers an oxidation-cleavage reaction,releasing methylene blue and coumarin,which emit distinct red and green fluorescence,respectively.This dual-emission feature enabled rapid HClO detection with two-channel detection limits of 25.13 nmol·L^(-1)(green channel)and 31.55 nmol·L^(-1)(red channel).Furthermore,in cell imaging experiments,this probe demonstrated excellent cell membrane permeability and low cytotoxicity,successfully enabling the monitoring of both endogenous and exogenous HClO in living cells.By incorporating a twochannel self-calibration system,the probe effectively mitigated signal variations caused by instrumental or environmental interference,substantially improving detection sensitivity and reliability.展开更多
By anchoring Tb^(3+)ions on its free carboxyl groups of the nanocaged NiMOF,a dual-emission self-calibrating sensor of Tb^(3+)@NiMOF was fabricated through coordination post-synthetic modification(PSM)strategy.With Tb...By anchoring Tb^(3+)ions on its free carboxyl groups of the nanocaged NiMOF,a dual-emission self-calibrating sensor of Tb^(3+)@NiMOF was fabricated through coordination post-synthetic modification(PSM)strategy.With Tb^(3+)ions as the secondary fluorescent signal and sensing active sites,Tb^(3+)@NiMOF presents great potentials in visually and efficiently monitoring EPI in serum,with high sensitivity and selectivity,fast response,excellent recyclable,and the low detection limit(LOD,3.06 ng/mL).Furthermore,a tandem combinational logic gate based intelligent detection system was constructed to improve the practicability and convenience of epinephrine(EPI)detection in serum by comparing the light emitted colour with the series standard colour cards preset in the smartphone.This work provides a promising approach of developing metal-organic frameworks(MOFs)based self-calibrating sensors for intelligent detection of bioactive molecules.展开更多
Humanβ-galactosidase(β-gal)is recognized as a crucial biomarker for evaluating senescence at the cellular and tissue levels in humans.However,tools to precisely track the endogenousβ-gal are still limited.Herein,we...Humanβ-galactosidase(β-gal)is recognized as a crucial biomarker for evaluating senescence at the cellular and tissue levels in humans.However,tools to precisely track the endogenousβ-gal are still limited.Herein,we present two novel self-calibratingβ-gal probes 7a and 7b which were constructed on a unique green/red dual-emissive fluorescence platform.The two probes inherently exhibited a stable green fluorescence signal impervious toβ-gal activity,serving as a reliable internal reference.They also displayed a progressively diminishing red fluorescence signal with the increasing ofβ-gal expression levels.The dual behavior endows them with self-calibration capacity and then renders excellently selective and sensitive for precisely monitoringβ-gal activity.Notably,compared with E.coliβ-gal,the two probes are more effectively response to A.oryzaeβ-gal homologous to humanβ-gal,indicating their unique species-selectivity.Furthermore,7a was validated for its effectiveness in determining senescenceassociatedβ-galactosidase(SA-β-gal)expression in senescent NRK-52E and HepG2 cells,underscoring its practical applicability in senescence research.展开更多
An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normali...An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future.展开更多
Developing an accurate and visual sensing strategy for trace levels of fluoroquinolone residues that pose threat to food safety and human health is highly desired but remains challenging.Herein,a target selfcalibratio...Developing an accurate and visual sensing strategy for trace levels of fluoroquinolone residues that pose threat to food safety and human health is highly desired but remains challenging.Herein,a target selfcalibration ratiometric fluorescent sensing platform has been designed for sensitive visual detection of levofloxacin(LEV)based on fluorescent europium metal-organic framework(Eu-MOF)probe.Specifically,the Eu-MOF was facilely synthesized via directly mixing Eu^(3+)with 1,10-phenanthroline-2,9-dicarboxylic acid(PDA)ligand at room temperature,which exhibited well-stable red fluorescence at 612 nm.Upon the addition of target LEV,the significant fluorescence quenching from Eu^(3+)was observed owing to the inner filter effect between the Eu-MOF and LEV.While the intrinsic fluorescence for LEV at 462nm was gradually enhanced,thereby realizing the self-calibration ratiometric fluorescence responses to LEV.Through this strategy,LEV can be detected down to 27 nmol/L.Furthermore,a test paper-based Eu-MOF integrated with the smartphone assisted RGB color analysis was exploited for the quantitative monitoring of LEV through the multi-color changes from red to blue,thus achieved portable,convenient and visual detection of LEV in honey and milk samples.Therefore,the developed strategy could provide a useful tool for supporting the practical on-site test in food samples.展开更多
A digital phase-locked loop （DPLL） based on a new digital phase-frequency detector is presented. The self-calibration technique is employed to acquire wide lock range,low jitter, and fast acquisition. The DPLL works...A digital phase-locked loop （DPLL） based on a new digital phase-frequency detector is presented. The self-calibration technique is employed to acquire wide lock range,low jitter, and fast acquisition. The DPLL works from 60 to 600MHz at a supply voltage of 1.8V. It also features a fraetional-N synthesizer with digital 2nd-order sigma-delta noise shaping, which can achieve a short lock time,a high frequency resolution,and an improved phase-noise spectrum. The DPLL has been implemented in SMIC 0. 18μm 1.8V 1P6M CMOS technology. The peak-to-peak jitter is less than 0. 8% of the output clock period and the lock time is less than 150 times of the reference clock period after the pre-divider.展开更多
A capacitor self-calibration circuit used in a successive approximation analog-to-digital converter （SA-ADC） is presented. This capacitor self-calibration circuit can calibrate erroneous data and work with the ADC b...A capacitor self-calibration circuit used in a successive approximation analog-to-digital converter （SA-ADC） is presented. This capacitor self-calibration circuit can calibrate erroneous data and work with the ADC by adding an additional clock period. This circuit is used in a 10 bit 32 Msample/s time-interleaved SA- ADC. The chip is implemented with Chart 0. 25 μm 2. 5 V process and totally occupies an area of 1.4 mm× 1.3 mm. After calibration, the simulated signal-to-noise ratio （SNR） is 59. 586 1 dB and the spurious-free dynamic range （SFDR） is 70. 246 dB at 32 MHz. The measured signal-to-noise and distortion ratio （SINAD） is 44. 82 dB and the SFDR is 63. 760 4 dB when the ADC samples a 5.8 MHz sinusoid wave.展开更多
Microstructured roll workpieces have been widely used as functional components in the precision industries. Current researches on quality control have focused on surface profile measurement of microstructured roll wor...Microstructured roll workpieces have been widely used as functional components in the precision industries. Current researches on quality control have focused on surface profile measurement of microstructured roll workpieces, and types of measurement systems and measurement methods have been developed. However, low measurement efficiency and low measurement accuracy caused by setting errors are the common disadvantages for surface profile measurement of microstructured roll workpieces. In order to shorten the measurement time and enhance the measurement accuracy, a method for self-calibration and compensation of setting errors is proposed for surface profile measurement of microstructured roll workpieces. A measurement system is constructed for the measurement, in which a precision spindle is employed to rotate the roll workpiece and an air-bearing displacement sensor with a micro-stylus probe is employed to scan the microstructured surface of the roll workpiece. The resolution of the displacement sensor is 0.14 nm and that of the rotary encoder of the spindle was 0.15r~. Geometrical and mathematical models are established for analyzing the influences of the setting errors of the roll workpiece and the displacement sensor with respect to the axis of the spindle, including the eccentric error of the roll workpiece, the offset error of the sensor axis and the zero point error of the sensor output. Measurement experiments are carded out on a roll workpiece on which periodic microstructures are a period of 133 i^m along the circumferential direction. Experimental results demonstrate the feasibility of the self-compensation method. The proposed method can be used to detect and compensate the setting errors without using any additional accurate artifact.展开更多
On the basis of local measurements of hydraulic conductivity, geostatistical methods have been found to be useful in heterogeneity characterization of a hydraulic conductivity field on a regional scale. However, the m...On the basis of local measurements of hydraulic conductivity, geostatistical methods have been found to be useful in heterogeneity characterization of a hydraulic conductivity field on a regional scale. However, the methods are not suited to directly integrate dynamic production data, such as, hydraulic head and solute concentration, into the study of conductivity distribution. These data, which record the flow and transport processes in the medium, are closely related to the spatial distribution of hydraulic conductivity. In this study, a three-dimensional gradient-based inverse method--the sequential self-calibration （SSC） method--is developed to calibrate a hydraulic conductivity field, initially generated by a geostatistical simulation method, conditioned on tracer test results. The SSC method can honor both local hydraulic conductivity measurements and tracer test data. The mismatch between the simulated hydraulic conductivity field and the reference true one, measured by its mean square error （MSE）, is reduced through the SSC conditional study. In comparison with the unconditional results, the SSC conditional study creates the mean breakthrough curve much closer to the reference true curve, and significantly reduces the prediction uncertainty of the solute transport in the observed locations. Further, the reduction of uncertainty is spatially dependent, which indicates that good locations, geological structure, and boundary conditions will affect the efficiency of the SSC study results.展开更多
To overcome the influence of on-orbit extreme temperature environment on the tool pose(position and orientation) accuracy of a space robot,a new self-calibration method based on a measurement camera(hand-eye vision) a...To overcome the influence of on-orbit extreme temperature environment on the tool pose(position and orientation) accuracy of a space robot,a new self-calibration method based on a measurement camera(hand-eye vision) attached to its end-effector was presented.Using the relative pose errors between the two adjacent calibration positions of the space robot,the cost function of the calibration was built,which was different from the conventional calibration method.The particle swarm optimization algorithm(PSO) was used to optimize the function to realize the geometrical parameter identification of the space robot.The above calibration method was carried out through self-calibration simulation of a six-DOF space robot whose end-effector was equipped with hand-eye vision.The results showed that after calibration there was a significant improvement of tool pose accuracy in a set of independent reference positions,which verified the feasibility of the method.At the same time,because it was unnecessary for this method to know the transformation matrix from the robot base to the calibration plate,it reduced the complexity of calibration model and shortened the error propagation chain,which benefited to improve the calibration accuracy.展开更多
In this study,the problem of bundle adjustment was revisited,and a novel algorithm based on block matrix Cholesky decomposition was proposed to solve the thorny problem of self-calibration bundle adjustment.The innova...In this study,the problem of bundle adjustment was revisited,and a novel algorithm based on block matrix Cholesky decomposition was proposed to solve the thorny problem of self-calibration bundle adjustment.The innovation points are reflected in the following aspects:①The proposed algorithm is not dependent on the Schur complement,and the calculation process is simple and clear;②The complexities of time and space tend to O(n)in the context of world point number is far greater than that of images and cameras,so the calculation magnitude and memory consumption can be reduced significantly;③The proposed algorithm can carry out self-calibration bundle adjustment in single-camera,multi-camera,and variable-camera modes;④Some measures are employed to improve the optimization effects.Experimental tests showed that the proposed algorithm has the ability to achieve state-of-the-art performance in accuracy and robustness,and it has a strong adaptability as well,because the optimized results are accurate and robust even if the initial values have large deviations from the truth.This study could provide theoretical guidance and technical support for the image-based positioning and 3D reconstruction in the fields of photogrammetry,computer vision and robotics.展开更多
An improved self-calibrating algorithm for visual servo based on adaptive genetic algorithm is proposed in this paper. Our approach introduces an extension of Mendonca-Cipolla and G. Chesi＇s self-calibration for the ...An improved self-calibrating algorithm for visual servo based on adaptive genetic algorithm is proposed in this paper. Our approach introduces an extension of Mendonca-Cipolla and G. Chesi＇s self-calibration for the positionbased visual servo technique which exploits the singular value property of the essential matrix. Specifically, a suitable dynamic online cost function is generated according to the property of the three singular values. The visual servo process is carried out simultaneous to the dynamic self-calibration, and then the cost function is minimized using the adaptive genetic algorithm instead of the gradient descent method in G. Chesi＇s approach. Moreover, this method overcomes the limitation that the initial parameters must be selected close to the true value, which is not constant in many cases. It is not necessary to know exactly the camera intrinsic parameters when using our approach, instead, coarse coding bounds of the five parameters are enough for the algorithm, which can be done once and for all off-line. Besides, this algorithm does not require knowledge of the 3D model of the object. Simulation experiments are carried out and the results demonstrate that the proposed approach provides a fast convergence speed and robustness against unpredictable perturbations of camera parameters, and it is an effective and efficient visual servo algorithm.展开更多
A key problem that plagues camera self-calibration, namely that the classical self-calibration algorithms are very sensitive to the initial values of the camera intrinsic parameters, is analyzed and a practical soluti...A key problem that plagues camera self-calibration, namely that the classical self-calibration algorithms are very sensitive to the initial values of the camera intrinsic parameters, is analyzed and a practical solution is provided. The effect of the camera intrinsic parameters, mainly the principal point and the skew factor is first discussed. Then a practical method via a controlled motion of the camera is introduced so as to obtain an accurate estimation of these parameters. Feasibility of this approach is illustrated by carrying out comprehensive experiments using synthetic data as well as real image sequences. Unreasonable initial values can often make self-calibration impossible, yet a precise initialization guarantees a better and successful reconstruction. Trying to obtain a more reasonable initialization is worthwhile the effort in camera self-calibration.展开更多
Laser tracking system （LTS） is an advanced device for large size 3D coordinates measuring with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the ...Laser tracking system （LTS） is an advanced device for large size 3D coordinates measuring with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the geometric errors of the tracking mirror mechanism. Proper calibration of LTS is essential prior to the use of it for metrology. A kinematics model that describes not only the motion but also the geometric variations of LTS is developed. Through error analysis of the proposed model, it is claimed that gimbals axis misalignments and tracking mirror center off-set are the key contributors to measuring errors of LTS. A self-calibration method is presented of calibrating LTS with planar constraints. Various calibration strategies utilizing single-plane and multiple-plane constraints are proposed for different situations. For each calibration strategy, issues about the error parameter estimation of LTS are exploded to find out in which conditions these parameters can be uniquely estimated. Moreover, these conditions reveal the applicability of the planar constraints to LTS self-calibration. Intensive studies have been made to check validity of the theoretical results. The results show that the measuring accuracy of LTS has increased by 5 times since this technique for calibration is used.展开更多
Aiming at piezoresistive pressure sensors, this paper studies simulation of standard pressure by using benchmark current source and self-calibration of the sampling data characteristics. A data fusion algorithm for sa...Aiming at piezoresistive pressure sensors, this paper studies simulation of standard pressure by using benchmark current source and self-calibration of the sampling data characteristics. A data fusion algorithm for sample set is presented which transforms a surface problem into a curve fitting and interpolation problem. The simulation result shows that benchmark current source simulating pressure is successful and data fusion algorithm is effective. The maximum measurement error is only 0.098 kPa and maximum relative error is 0.92% at 0-45 kPa and -10-45~C.展开更多
In the field of converting simulation surveying and traditional close range photogrammetry, it has been developed so far to survey objects by commercial digital camera and this technique is applied widely in every par...In the field of converting simulation surveying and traditional close range photogrammetry, it has been developed so far to survey objects by commercial digital camera and this technique is applied widely in every part of production. In order to get three-dimensional information of objects, commercial digital camera must be examined. For a long time, digital camera has been examined by DLT. Then there must be a high-precision control field. For realizing surveying without control points, a method for self-calibration is proposed.展开更多
Land-use and land-cover change(LUCC)simulations are powerful tools for evaluating and predicting future landscape dynamics amid rapid human-nature interactions to support decision-making.However,existing models often ...Land-use and land-cover change(LUCC)simulations are powerful tools for evaluating and predicting future landscape dynamics amid rapid human-nature interactions to support decision-making.However,existing models often overlook spatial heterogeneity and temporal dependencies when modeling LUCC at both the macro and microscales.In this paper,we propose a new model,a self-calibrated convolutional neural network-based cellular automata(SC–CNN–CA)model,which integrates macro-and microspatial characteristics to simulate complex interactions among land-use types.The SC-CNN-CA model incorporates a self-calibration module using Gaussian functions to capture macrotrend such as urban sprawl while accounting for microlevel land-use interactions such as neighborhood effects.The results indicated that(1)the neighborhood effect between agricultural land and urban land tended to“increase followed by a decrease.”(2)Urban sprawl in Wuhan was highly compact,with a relatively high intensity of urban expansion at distances between 11.96 km and 24.44 km.(3)Compared with the other CA models tested,the SC-CNN-CA model demonstrated superior performance,achieving an overall accuracy of 84.12% and a figure of merit of 20.20%.This new model can enhance our understanding of historical LUCC trajectories and improve predictions of spatially explicit information for efficient land resource and urban management.展开更多
Objective:To prospectively follow up a cohort of anterior urethral stricture disease patients managed with balloon dilation(BD)for 3 years to evaluate the long-term outcomes and to study factors that contribute to rec...Objective:To prospectively follow up a cohort of anterior urethral stricture disease patients managed with balloon dilation(BD)for 3 years to evaluate the long-term outcomes and to study factors that contribute to recurrence.Methods:This study included men who had urethral BD for significant anterior urethral stricture disease between January 2017 and March 2019.Data about the patient age,stricture characteristics,and recurrence date were recorded,along with information on postoperative indwelling catheter use and operative complications.Furthermore,information about the self-calibration procedure was collected and where available,free flow(FF)measurements during the follow-up period were recorded and analyzed.Success was defined as a lack of symptoms and acceptable FF rates(maximum flow rate>12 mL/s).Results:The final analysis was conducted on 187 patients.The mean follow-up period was 37 months.The long-term overall success rate at the end of our study was 66.8%.Our recurrence rate was 7.4%at 12 months,24.7%at 24 months,and reached 33.2%at the end of our study.The time to recurrence ranged from 91 days to 1635 days,with a mean of 670 days.The stricture-free survival was significantly shorter with lengthy peno-bulbar(p=0.031)and multiple strictures(p=0.015),and in the group of patients who were not committed to self-calibration protocol(p<0.011).However,post-procedural self-calibration was the most important factor that may have decreased the incidence of recurrence(odds ratioZ5.85).Adjuvant self-calibration after BD not only reduced the recurrence rate from 85.4%in the non-self-calibration group to 15.1%in the self-calibration one(p<0.001),but also improved the overall stricture-free survival and FF parameters.展开更多
Based on the monthly precipitation and air temperature from 1960 to 1989 in the Luanhe River Basin, the standardized precipitation evapotranspiration index （SPEI） and standardized precipitation index （SPI） at thre...Based on the monthly precipitation and air temperature from 1960 to 1989 in the Luanhe River Basin, the standardized precipitation evapotranspiration index （SPEI） and standardized precipitation index （SPI） at three- and six-month time scales and the self-calibrating Palmer drought severity index （sc-PDSI） were calculated to evaluate droughts in the study area. Temporal variations of the drought severity from 1960 to 1989 were analyzed and compared based on the results of different drought indices, and some typical drought events were identified. Spatial distributions of the drought severity according to the indices were also plotted and investigated. The results reveal the following： the performances of different drought indices are closely associated with the drought duration and the dominant factors of droughts; the SPEI is more accurate than the SPI when both evaporation and precipitation play important roles in drought events; the drought severity shown by the sc-PDSI is generally milder than the actual drought severity from 1960 to 1989; and the evolution of the droughts is usually delayed according to the scPDSI. This study provides valuable references for building drought early warning and mitigation systems in the Luanhe River Basin.展开更多
Incorporation of luminescent moieties into metal-organic frameworks（MOFs） has resulted in numerous photoluminescence（PL） sensors based on chromophore-analyte interactions. However, most of them are only highly sen...Incorporation of luminescent moieties into metal-organic frameworks（MOFs） has resulted in numerous photoluminescence（PL） sensors based on chromophore-analyte interactions. However, most of them are only highly sensitive to few analytes limited by the single luminescent centers in MOFs. To improve the application scopes, dual-emission MOFs were therefore emerged, which can significantly improve the sensitivity by monitoring the relative emission intensity of two luminescent centers. This short review will highlight the recent progress on dual-emission MOFs as highly sensitive sensors for probing of volatile organic molecules（VOMs）, picric acid and peroxynitrite, and as self-calibration PL thermometer.展开更多
文摘In this study,a self-calibrating near-infrared fluorescence probe was designed and synthesized based on the dual-fluorophore strategy utilizing methylene blue and coumarin.The probe utilized methylene blue(emission spectrum range:640-740 nm)and coumarin fluorophore(emission spectrum range:440-600 nm)as signal output units,thereby achieving effective spectral separation and highly selective detection of HClO.Under physiological pH conditions,HClO triggers an oxidation-cleavage reaction,releasing methylene blue and coumarin,which emit distinct red and green fluorescence,respectively.This dual-emission feature enabled rapid HClO detection with two-channel detection limits of 25.13 nmol·L^(-1)(green channel)and 31.55 nmol·L^(-1)(red channel).Furthermore,in cell imaging experiments,this probe demonstrated excellent cell membrane permeability and low cytotoxicity,successfully enabling the monitoring of both endogenous and exogenous HClO in living cells.By incorporating a twochannel self-calibration system,the probe effectively mitigated signal variations caused by instrumental or environmental interference,substantially improving detection sensitivity and reliability.
基金Project supported by the National Natural Science Foundation of China(21801230,21905255)Natural Science Foundation of Shanxi Province(202203021211090)+2 种基金Young Academic Leader Supported Program of North University of China(QX201904)Shanxi Key Laboratory of Advanced Carbon Electrode Materials(202104010910019)The Key Laboratory Research Foundation of North University of China。
文摘By anchoring Tb^(3+)ions on its free carboxyl groups of the nanocaged NiMOF,a dual-emission self-calibrating sensor of Tb^(3+)@NiMOF was fabricated through coordination post-synthetic modification(PSM)strategy.With Tb^(3+)ions as the secondary fluorescent signal and sensing active sites,Tb^(3+)@NiMOF presents great potentials in visually and efficiently monitoring EPI in serum,with high sensitivity and selectivity,fast response,excellent recyclable,and the low detection limit(LOD,3.06 ng/mL).Furthermore,a tandem combinational logic gate based intelligent detection system was constructed to improve the practicability and convenience of epinephrine(EPI)detection in serum by comparing the light emitted colour with the series standard colour cards preset in the smartphone.This work provides a promising approach of developing metal-organic frameworks(MOFs)based self-calibrating sensors for intelligent detection of bioactive molecules.
基金the financial support from the National Natural Science Foundation of China(Nos.21977082,22037002and 21472148)the Natural Science Basic Research Program of Shaanxi(No.2020JC-38)。
文摘Humanβ-galactosidase(β-gal)is recognized as a crucial biomarker for evaluating senescence at the cellular and tissue levels in humans.However,tools to precisely track the endogenousβ-gal are still limited.Herein,we present two novel self-calibratingβ-gal probes 7a and 7b which were constructed on a unique green/red dual-emissive fluorescence platform.The two probes inherently exhibited a stable green fluorescence signal impervious toβ-gal activity,serving as a reliable internal reference.They also displayed a progressively diminishing red fluorescence signal with the increasing ofβ-gal expression levels.The dual behavior endows them with self-calibration capacity and then renders excellently selective and sensitive for precisely monitoringβ-gal activity.Notably,compared with E.coliβ-gal,the two probes are more effectively response to A.oryzaeβ-gal homologous to humanβ-gal,indicating their unique species-selectivity.Furthermore,7a was validated for its effectiveness in determining senescenceassociatedβ-galactosidase(SA-β-gal)expression in senescent NRK-52E and HepG2 cells,underscoring its practical applicability in senescence research.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61905039)Jilin Scientific and Technological Development Program, China (Grant No. 20190701018GH)+1 种基金Education Department of Jilin Province, China (Grant No. JJKH20190691KJ)State Key Laboratory of Applied Optics.
文摘An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future.
基金supported by the National Natural Science Foundation of China(Nos.32260247 and 22064010)the Natural Science Foundation of Jiangxi Province(Nos.20232BAB215071 and 20224BAB213009).
文摘Developing an accurate and visual sensing strategy for trace levels of fluoroquinolone residues that pose threat to food safety and human health is highly desired but remains challenging.Herein,a target selfcalibration ratiometric fluorescent sensing platform has been designed for sensitive visual detection of levofloxacin(LEV)based on fluorescent europium metal-organic framework(Eu-MOF)probe.Specifically,the Eu-MOF was facilely synthesized via directly mixing Eu^(3+)with 1,10-phenanthroline-2,9-dicarboxylic acid(PDA)ligand at room temperature,which exhibited well-stable red fluorescence at 612 nm.Upon the addition of target LEV,the significant fluorescence quenching from Eu^(3+)was observed owing to the inner filter effect between the Eu-MOF and LEV.While the intrinsic fluorescence for LEV at 462nm was gradually enhanced,thereby realizing the self-calibration ratiometric fluorescence responses to LEV.Through this strategy,LEV can be detected down to 27 nmol/L.Furthermore,a test paper-based Eu-MOF integrated with the smartphone assisted RGB color analysis was exploited for the quantitative monitoring of LEV through the multi-color changes from red to blue,thus achieved portable,convenient and visual detection of LEV in honey and milk samples.Therefore,the developed strategy could provide a useful tool for supporting the practical on-site test in food samples.
文摘A digital phase-locked loop （DPLL） based on a new digital phase-frequency detector is presented. The self-calibration technique is employed to acquire wide lock range,low jitter, and fast acquisition. The DPLL works from 60 to 600MHz at a supply voltage of 1.8V. It also features a fraetional-N synthesizer with digital 2nd-order sigma-delta noise shaping, which can achieve a short lock time,a high frequency resolution,and an improved phase-noise spectrum. The DPLL has been implemented in SMIC 0. 18μm 1.8V 1P6M CMOS technology. The peak-to-peak jitter is less than 0. 8% of the output clock period and the lock time is less than 150 times of the reference clock period after the pre-divider.
文摘A capacitor self-calibration circuit used in a successive approximation analog-to-digital converter （SA-ADC） is presented. This capacitor self-calibration circuit can calibrate erroneous data and work with the ADC by adding an additional clock period. This circuit is used in a 10 bit 32 Msample/s time-interleaved SA- ADC. The chip is implemented with Chart 0. 25 μm 2. 5 V process and totally occupies an area of 1.4 mm× 1.3 mm. After calibration, the simulated signal-to-noise ratio （SNR） is 59. 586 1 dB and the spurious-free dynamic range （SFDR） is 70. 246 dB at 32 MHz. The measured signal-to-noise and distortion ratio （SINAD） is 44. 82 dB and the SFDR is 63. 760 4 dB when the ADC samples a 5.8 MHz sinusoid wave.
文摘Microstructured roll workpieces have been widely used as functional components in the precision industries. Current researches on quality control have focused on surface profile measurement of microstructured roll workpieces, and types of measurement systems and measurement methods have been developed. However, low measurement efficiency and low measurement accuracy caused by setting errors are the common disadvantages for surface profile measurement of microstructured roll workpieces. In order to shorten the measurement time and enhance the measurement accuracy, a method for self-calibration and compensation of setting errors is proposed for surface profile measurement of microstructured roll workpieces. A measurement system is constructed for the measurement, in which a precision spindle is employed to rotate the roll workpiece and an air-bearing displacement sensor with a micro-stylus probe is employed to scan the microstructured surface of the roll workpiece. The resolution of the displacement sensor is 0.14 nm and that of the rotary encoder of the spindle was 0.15r~. Geometrical and mathematical models are established for analyzing the influences of the setting errors of the roll workpiece and the displacement sensor with respect to the axis of the spindle, including the eccentric error of the roll workpiece, the offset error of the sensor axis and the zero point error of the sensor output. Measurement experiments are carded out on a roll workpiece on which periodic microstructures are a period of 133 i^m along the circumferential direction. Experimental results demonstrate the feasibility of the self-compensation method. The proposed method can be used to detect and compensate the setting errors without using any additional accurate artifact.
基金This study is partially supported by the Program of Outstanding Overseas Youth Chinese Scholar,the National Natural Science Foundation of China (No. 40528003)partially supported by USA National Science Foundation.
文摘On the basis of local measurements of hydraulic conductivity, geostatistical methods have been found to be useful in heterogeneity characterization of a hydraulic conductivity field on a regional scale. However, the methods are not suited to directly integrate dynamic production data, such as, hydraulic head and solute concentration, into the study of conductivity distribution. These data, which record the flow and transport processes in the medium, are closely related to the spatial distribution of hydraulic conductivity. In this study, a three-dimensional gradient-based inverse method--the sequential self-calibration （SSC） method--is developed to calibrate a hydraulic conductivity field, initially generated by a geostatistical simulation method, conditioned on tracer test results. The SSC method can honor both local hydraulic conductivity measurements and tracer test data. The mismatch between the simulated hydraulic conductivity field and the reference true one, measured by its mean square error （MSE）, is reduced through the SSC conditional study. In comparison with the unconditional results, the SSC conditional study creates the mean breakthrough curve much closer to the reference true curve, and significantly reduces the prediction uncertainty of the solute transport in the observed locations. Further, the reduction of uncertainty is spatially dependent, which indicates that good locations, geological structure, and boundary conditions will affect the efficiency of the SSC study results.
基金Projects(60775049,60805033) supported by the National Natural Science Foundation of ChinaProject(2007AA704317) supported by the National High Technology Research and Development Program of China
文摘To overcome the influence of on-orbit extreme temperature environment on the tool pose(position and orientation) accuracy of a space robot,a new self-calibration method based on a measurement camera(hand-eye vision) attached to its end-effector was presented.Using the relative pose errors between the two adjacent calibration positions of the space robot,the cost function of the calibration was built,which was different from the conventional calibration method.The particle swarm optimization algorithm(PSO) was used to optimize the function to realize the geometrical parameter identification of the space robot.The above calibration method was carried out through self-calibration simulation of a six-DOF space robot whose end-effector was equipped with hand-eye vision.The results showed that after calibration there was a significant improvement of tool pose accuracy in a set of independent reference positions,which verified the feasibility of the method.At the same time,because it was unnecessary for this method to know the transformation matrix from the robot base to the calibration plate,it reduced the complexity of calibration model and shortened the error propagation chain,which benefited to improve the calibration accuracy.
基金National Natural Science Foundation of China(Nos.41571410,41977067,42171422)。
文摘In this study,the problem of bundle adjustment was revisited,and a novel algorithm based on block matrix Cholesky decomposition was proposed to solve the thorny problem of self-calibration bundle adjustment.The innovation points are reflected in the following aspects:①The proposed algorithm is not dependent on the Schur complement,and the calculation process is simple and clear;②The complexities of time and space tend to O(n)in the context of world point number is far greater than that of images and cameras,so the calculation magnitude and memory consumption can be reduced significantly;③The proposed algorithm can carry out self-calibration bundle adjustment in single-camera,multi-camera,and variable-camera modes;④Some measures are employed to improve the optimization effects.Experimental tests showed that the proposed algorithm has the ability to achieve state-of-the-art performance in accuracy and robustness,and it has a strong adaptability as well,because the optimized results are accurate and robust even if the initial values have large deviations from the truth.This study could provide theoretical guidance and technical support for the image-based positioning and 3D reconstruction in the fields of photogrammetry,computer vision and robotics.
基金the National Natural Science Foundation of China (No.60675048)Science and Technology Research Project of the Ministry of Education (No.204181).
文摘An improved self-calibrating algorithm for visual servo based on adaptive genetic algorithm is proposed in this paper. Our approach introduces an extension of Mendonca-Cipolla and G. Chesi＇s self-calibration for the positionbased visual servo technique which exploits the singular value property of the essential matrix. Specifically, a suitable dynamic online cost function is generated according to the property of the three singular values. The visual servo process is carried out simultaneous to the dynamic self-calibration, and then the cost function is minimized using the adaptive genetic algorithm instead of the gradient descent method in G. Chesi＇s approach. Moreover, this method overcomes the limitation that the initial parameters must be selected close to the true value, which is not constant in many cases. It is not necessary to know exactly the camera intrinsic parameters when using our approach, instead, coarse coding bounds of the five parameters are enough for the algorithm, which can be done once and for all off-line. Besides, this algorithm does not require knowledge of the 3D model of the object. Simulation experiments are carried out and the results demonstrate that the proposed approach provides a fast convergence speed and robustness against unpredictable perturbations of camera parameters, and it is an effective and efficient visual servo algorithm.
文摘A key problem that plagues camera self-calibration, namely that the classical self-calibration algorithms are very sensitive to the initial values of the camera intrinsic parameters, is analyzed and a practical solution is provided. The effect of the camera intrinsic parameters, mainly the principal point and the skew factor is first discussed. Then a practical method via a controlled motion of the camera is introduced so as to obtain an accurate estimation of these parameters. Feasibility of this approach is illustrated by carrying out comprehensive experiments using synthetic data as well as real image sequences. Unreasonable initial values can often make self-calibration impossible, yet a precise initialization guarantees a better and successful reconstruction. Trying to obtain a more reasonable initialization is worthwhile the effort in camera self-calibration.
基金National Natural Science Foundation of China (No. 50475038).
文摘Laser tracking system （LTS） is an advanced device for large size 3D coordinates measuring with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the geometric errors of the tracking mirror mechanism. Proper calibration of LTS is essential prior to the use of it for metrology. A kinematics model that describes not only the motion but also the geometric variations of LTS is developed. Through error analysis of the proposed model, it is claimed that gimbals axis misalignments and tracking mirror center off-set are the key contributors to measuring errors of LTS. A self-calibration method is presented of calibrating LTS with planar constraints. Various calibration strategies utilizing single-plane and multiple-plane constraints are proposed for different situations. For each calibration strategy, issues about the error parameter estimation of LTS are exploded to find out in which conditions these parameters can be uniquely estimated. Moreover, these conditions reveal the applicability of the planar constraints to LTS self-calibration. Intensive studies have been made to check validity of the theoretical results. The results show that the measuring accuracy of LTS has increased by 5 times since this technique for calibration is used.
基金Project supported by the National Natural Science Foundation of China （Grant No.40265001）, and the Science Foundation of Yunnan Province （Grant No.2002C0038M）
文摘Aiming at piezoresistive pressure sensors, this paper studies simulation of standard pressure by using benchmark current source and self-calibration of the sampling data characteristics. A data fusion algorithm for sample set is presented which transforms a surface problem into a curve fitting and interpolation problem. The simulation result shows that benchmark current source simulating pressure is successful and data fusion algorithm is effective. The maximum measurement error is only 0.098 kPa and maximum relative error is 0.92% at 0-45 kPa and -10-45~C.
文摘In the field of converting simulation surveying and traditional close range photogrammetry, it has been developed so far to survey objects by commercial digital camera and this technique is applied widely in every part of production. In order to get three-dimensional information of objects, commercial digital camera must be examined. For a long time, digital camera has been examined by DLT. Then there must be a high-precision control field. For realizing surveying without control points, a method for self-calibration is proposed.
基金National Natural Science Foundation of China,No.42101259,No.42371101,No.42301455Young Science and Technology New Star Project of Shaanxi Province,No.2024ZC-KJXX-013+3 种基金Qin Chuangyuan Cites High-level Innovation or Entrepreneurship Talent Project,No.QCYRCXM-2023-066Fifth Batch Special Funding(Pre-Station)from China Postdoctoral Science Foundation,No.2023TQ0207Fundamental Research Funds for the Central Universities,No.GK202304024,No.1110011297,No.1112010355Teaching Reform Project of Shaanxi Normal University,No.23GGYS-JG06。
文摘Land-use and land-cover change(LUCC)simulations are powerful tools for evaluating and predicting future landscape dynamics amid rapid human-nature interactions to support decision-making.However,existing models often overlook spatial heterogeneity and temporal dependencies when modeling LUCC at both the macro and microscales.In this paper,we propose a new model,a self-calibrated convolutional neural network-based cellular automata(SC–CNN–CA)model,which integrates macro-and microspatial characteristics to simulate complex interactions among land-use types.The SC-CNN-CA model incorporates a self-calibration module using Gaussian functions to capture macrotrend such as urban sprawl while accounting for microlevel land-use interactions such as neighborhood effects.The results indicated that(1)the neighborhood effect between agricultural land and urban land tended to“increase followed by a decrease.”(2)Urban sprawl in Wuhan was highly compact,with a relatively high intensity of urban expansion at distances between 11.96 km and 24.44 km.(3)Compared with the other CA models tested,the SC-CNN-CA model demonstrated superior performance,achieving an overall accuracy of 84.12% and a figure of merit of 20.20%.This new model can enhance our understanding of historical LUCC trajectories and improve predictions of spatially explicit information for efficient land resource and urban management.
文摘Objective:To prospectively follow up a cohort of anterior urethral stricture disease patients managed with balloon dilation(BD)for 3 years to evaluate the long-term outcomes and to study factors that contribute to recurrence.Methods:This study included men who had urethral BD for significant anterior urethral stricture disease between January 2017 and March 2019.Data about the patient age,stricture characteristics,and recurrence date were recorded,along with information on postoperative indwelling catheter use and operative complications.Furthermore,information about the self-calibration procedure was collected and where available,free flow(FF)measurements during the follow-up period were recorded and analyzed.Success was defined as a lack of symptoms and acceptable FF rates(maximum flow rate>12 mL/s).Results:The final analysis was conducted on 187 patients.The mean follow-up period was 37 months.The long-term overall success rate at the end of our study was 66.8%.Our recurrence rate was 7.4%at 12 months,24.7%at 24 months,and reached 33.2%at the end of our study.The time to recurrence ranged from 91 days to 1635 days,with a mean of 670 days.The stricture-free survival was significantly shorter with lengthy peno-bulbar(p=0.031)and multiple strictures(p=0.015),and in the group of patients who were not committed to self-calibration protocol(p<0.011).However,post-procedural self-calibration was the most important factor that may have decreased the incidence of recurrence(odds ratioZ5.85).Adjuvant self-calibration after BD not only reduced the recurrence rate from 85.4%in the non-self-calibration group to 15.1%in the self-calibration one(p<0.001),but also improved the overall stricture-free survival and FF parameters.
基金supported by the National Natural Science Foundation of China(Grant No.41171220)the Program for Changjiang Scholars and Innovative Research Team in University of the Ministry of Education of China(Grant No.IRT13062)+2 种基金the Programme of Introducing Talents of Discipline to Universities(the 111 Project,Grant No.B08048)the Jiangsu Provincial Collaborative Innovation Center for World Water Valley and Water Ecological Civilizationthe National Cooperative Innovation Center for Water Safety and Hydro-Science
文摘Based on the monthly precipitation and air temperature from 1960 to 1989 in the Luanhe River Basin, the standardized precipitation evapotranspiration index （SPEI） and standardized precipitation index （SPI） at three- and six-month time scales and the self-calibrating Palmer drought severity index （sc-PDSI） were calculated to evaluate droughts in the study area. Temporal variations of the drought severity from 1960 to 1989 were analyzed and compared based on the results of different drought indices, and some typical drought events were identified. Spatial distributions of the drought severity according to the indices were also plotted and investigated. The results reveal the following： the performances of different drought indices are closely associated with the drought duration and the dominant factors of droughts; the SPEI is more accurate than the SPI when both evaporation and precipitation play important roles in drought events; the drought severity shown by the sc-PDSI is generally milder than the actual drought severity from 1960 to 1989; and the evolution of the droughts is usually delayed according to the scPDSI. This study provides valuable references for building drought early warning and mitigation systems in the Luanhe River Basin.
基金the financial support of the National Natural Science Foundation of China (Nos. 21373180 and 21525312)the Fundamental Research Funds for the Central Universities (Nos. 2017XZZX001-03A and 2017FZA3007)
文摘Incorporation of luminescent moieties into metal-organic frameworks（MOFs） has resulted in numerous photoluminescence（PL） sensors based on chromophore-analyte interactions. However, most of them are only highly sensitive to few analytes limited by the single luminescent centers in MOFs. To improve the application scopes, dual-emission MOFs were therefore emerged, which can significantly improve the sensitivity by monitoring the relative emission intensity of two luminescent centers. This short review will highlight the recent progress on dual-emission MOFs as highly sensitive sensors for probing of volatile organic molecules（VOMs）, picric acid and peroxynitrite, and as self-calibration PL thermometer.
