As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding...As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.展开更多
The conversion of CO_(2)to dimethyl carbonate(DMC)offers a promising route for CO_(2)utilization.In this study,four CeO2 catalysts with distinct nanostructures were synthesized via a template-free hydrothermal method ...The conversion of CO_(2)to dimethyl carbonate(DMC)offers a promising route for CO_(2)utilization.In this study,four CeO2 catalysts with distinct nanostructures were synthesized via a template-free hydrothermal method by systematically varying the types and concentrations of precipitants as well as the hydrothermal reaction conditions,and they were employed for DMC synthesis from CO_(2)and methanol.The atomic arrangements of CeO_(2)varied significantly with its morphology,leading to differences in lattice distortion,which directly influenced the concentration of oxygen vacancies.Notably,the CeO_(2)nanospheres,which exhibited the highest lattice distortion and oxygen vacancy concentration,achieved a DMC yield(11.12 mmol/g)48 times greater than that of the nanocubes(0.23 mmol/g).The results indicated that oxygen vacancies played a pivotal role in the catalytic process by facilitating the adsorption and activation of CO_(2)to form bidentate carbonates,as well as activating methanol to generate methoxy species.These processes collectively promoted the formation of the key intermediate(*CH3OCOO).This study proposes a strategy to enhance the oxygen vacancy concentration by increasing lattice distortion,providing valuable insights for designing high-performance CeO_(2)catalysts for DMC synthesis.展开更多
Collecting amounts of distorted/clean image pairs in the real world is non-trivial,which severely limits the practical application of these supervised learning-based methods to real-world image super-resolution(RealSR...Collecting amounts of distorted/clean image pairs in the real world is non-trivial,which severely limits the practical application of these supervised learning-based methods to real-world image super-resolution(RealSR).Previous works usually address this problem by leveraging unsupervised learning-based technologies to alleviate the dependency on paired training samples.However,these methods typically suffer from unsatisfactory texture synthesis due to the lack of supervision of clean images.To overcome this problem,we are the first to take a close look at the under-explored direction for RealSR,i.e.,few-shot real-world image super-resolution,which aims to tackle the challenging RealSR problem with few-shot distorted/clean image pairs.Under this brand-new scenario,we propose distortion relation guided transfer learning(DRTL)for the few-shot RealSR by transferring the rich restoration knowledge from auxiliary distortions(i.e.,synthetic distortions)to the target RealSR under the guidance of the distortion relation.Concretely,DRTL builds a knowledge graph to capture the distortion relation between auxiliary distortions and target distortion(i.e.,real distortions in RealSR).Based on the distortion relation,DRTL adopts a gradient reweighting strategy to guide the knowledge transfer process between auxiliary distortions and target distortions.In this way,DRTL is able to quickly learn the most relevant knowledge from the synthetic distortions for the target distortion.We instantiate DRTL with two commonly-used transfer learning paradigms,including pretraining and meta-learning pipelines,to realize a distortion relation-aware few-shot RealSR.Extensive experiments on multiple benchmarks and thorough ablation studies demonstrate the effectiveness of our DRTL.展开更多
In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as...In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line.Both methods are straightforward to implement,robust against noise,and applicable to a wide range of qubit types.The two methods differ in correction accuracy and complexity.The first,coarse predistortion(CPD)method,partially mitigates distortion.The second,all predistortion(APD)method,measures the transfer function and significantly enhances exchange oscillation uniformity.Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse.We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.展开更多
The traditional orbit determination method based on pulsar profile distortion can determine the six elements of the orbit.However,the estimation accuracies of these methods are limited and the computational load of a ...The traditional orbit determination method based on pulsar profile distortion can determine the six elements of the orbit.However,the estimation accuracies of these methods are limited and the computational load of a six-dimensional search is huge.To solve this problem,the differential-geometry-based Multi-dimensional Joint Position-Velocity Estimation(MJPVE)using Crab pulsar profile distortion is proposed in this paper.Firstly,through theoretical analysis,it is found that the pulsar profile distortion caused by the initial state error in some joint positionvelocity directions is very small.In other words,the accuracies of estimation in these directions are very low.Namely,the search dimension can be reduced,which in turn greatly reduces the computational load.Then,we construct the chi-squared function of the pulsar profile with respect to the estimation error in joint position-velocity direction and use differential geometry to find the joint position-velocity directions corresponding to different degrees of distortion.Finally,we utilize the grid search based on directory folding in these joint position-velocity directions corresponding to large degrees of distortion to obtain the joint position-velocity estimation.The experimental results show that compared with the grouping bi-chi-squared inversion method,MJPVE has high precision and extensive navigation information.展开更多
Fe-N-C catalysts are promising substitutes for precious-metal platinum in acidic oxygen reduction reactions(ORR),yet their moderate intrinsic activity and susceptibility to reactive oxygen species(ROS)-induced degrada...Fe-N-C catalysts are promising substitutes for precious-metal platinum in acidic oxygen reduction reactions(ORR),yet their moderate intrinsic activity and susceptibility to reactive oxygen species(ROS)-induced degradation hinder practical implementation.Herein,we fabricate a Ru-Fe dual-site catalyst(RuFe-N-C)through a two-step pyrolysis strategy.Structural characterization reveals atomic-scale proximity between Ru single atoms and Fe-N_(4) moieties,exhibiting a projected distance of~1.7Å.This configuration induces Fe–N bond elongation accompanied by 2.5%lattice distortion.The optimized RuFe-N-C catalyst exhibits high ORR performance,with a half-wave potential(E_(1/2))of 0.840 V and peak power density(P_(max))of 938 mW cm^(-2) under 150 kPa absolute H_(2)-O_(2).These metrics signify substantial enhancements relative to conventional Fe-N-C benchmarks(+21 mV in E_(1/2) and+42%in P_(max)).Moreover,the catalyst maintains outstanding stability,showing merely 17 mV E_(1/2) decay after 10000 accelerated durability test(ADT)cycles.Experimental analyses reveal a bifunctional mechanism:(1)Adjacent Ru sites substantially enhance the intrinsic ORR activity of Fe-N_(4) moieties,delivering a notable turnover frequency(TOF=17.86 e site^(-1) s^(-1) at 0.85 V vs.RHE)that exceeds state-of-the-art Fe-N-C benchmarks by 1-2 orders of magnitude(<1 e site^(-1) s^(-1));(2)Ru centers function as electron relays that facilitate ROS scavenging,thus suppressing degradation.This work establishes a paradigm for engineering bimetallic single-atom catalysts through synergistic electronic modulation to concurrently enhance activity and stability.展开更多
To eliminate distortion caused by vertical drift and illusory slopes in atomic force microscopy(AFM)imaging,a lifting-wavelet-based iterative thresholding correction method is proposed in this paper.This method achiev...To eliminate distortion caused by vertical drift and illusory slopes in atomic force microscopy(AFM)imaging,a lifting-wavelet-based iterative thresholding correction method is proposed in this paper.This method achieves high-quality AFM imaging via line-by-line corrections for each distorted profile along the fast axis.The key to this line-by-line correction is to accurately simulate the profile distortion of each scanning row.Therefore,a data preprocessing approach is first developed to roughly filter out most of the height data that impairs the accuracy of distortion modeling.This process is implemented through an internal double-screening mechanism.A line-fitting method is adopted to preliminarily screen out the obvious specimens.Lifting wavelet analysis is then carried out to identify the base parts that are mistakenly filtered out as specimens so as to preserve most of the base profiles and provide a good basis for further distortion modeling.Next,an iterative thresholding algorithm is developed to precisely simulate the profile distortion.By utilizing the roughly screened base profile,the optimal threshold,which is used to screen out the pure bases suitable for distortion modeling,is determined through iteration with a specified error rule.On this basis,the profile distortion is accurately modeled through line fitting on the finely screened base data,and the correction is implemented by subtracting the modeling result from the distorted profile.Finally,the effectiveness of the proposed method is verified through experiments and applications.展开更多
Jahn-Teller distortion(JTD)remains a fundamental bottleneck for transition metal oxides(TMOs)in electrochemical energy storage,where the e_(g)-orbital single-electron occupancy induces irreversible octahedral collapse...Jahn-Teller distortion(JTD)remains a fundamental bottleneck for transition metal oxides(TMOs)in electrochemical energy storage,where the e_(g)-orbital single-electron occupancy induces irreversible octahedral collapse and rapid capacity fading.Here,we pioneer an itinerant-electron-mediated dynamic suppression strategy that fundamentally reshapes the JTD evolution pathway throughπ-d orbital hybridization engineering.By constructing reduced graphene oxide/TMO heterointerfaces(rGO/MO_(x),M=Fe/Ni/Mn),localized 3d electrons are transformed into delocalized itinerant states,which(1)eliminate e_(g)-band degeneracy via orbital repopulation and(2)establish an electron density buffer layer to neutralize lattice strain.This electronic regulation enables ultrafast Na^(+)diffusion kinetics(508.3 F g^(−1)at 1 A g^(−1)→304.6 F g^(−1)at 20 A g^(−1))and near-zero lattice deformation(91.07%capacitance retention after 20,000 cycles).Synchrotron-based X-ray absorption spectroscopy and density functional theory calculations reveal that itinerant electron dynamics actively decouple the Mn^(3+)d^(4)electronic configuration from JTD triggering,leading to a dramatic suppression of octahedral distortion compared to the conventional MnO_(2).The proposed electron delocalization-to-lattice stabilization paradigm opens a universal route to design distortion-resistant electrodes for high-power energy storage systems.展开更多
Efficient and stable electrocatalysts are essential for seawater splitting to sustain electrolysis without chloride corrosion,particularly at the anode.Furthermore,the oxygen evolution reaction(OER)requires high overp...Efficient and stable electrocatalysts are essential for seawater splitting to sustain electrolysis without chloride corrosion,particularly at the anode.Furthermore,the oxygen evolution reaction(OER)requires high overpotential due to the universal scaling relationship.Herein,molybdenum doping FeNi_(2)Se_(4)with lattice distortion is proposed to break the scaling relationship.Mo-FeNi_(2)Se_(4)shows high performance in direct seawater electrolysis and achieves current densities of 10 and 100 mA cm^(−2) at overpotentials of 190 and 250 mV,respectively,together with high OER selectivity and long-term stability.It is found that the lattice distortion induced by Mo doping in(3 1 0)plane of FeNi_(2)Se_(4),leads to a decrease in the d-band center and the adsorption energy of ^(*)O,which not only breaks the scaling relationship of OER but also lowers the energy barriers of rate-determining step.Moreover,it enhances the corrosion resistance to Cl^(−),and realizes the high-efficiency seawater electrolysis driven by photovoltaic.展开更多
The estimation of orientation parameters and correction of lens distortion are crucial problems in the field of Unmanned Aerial Vehicles(UAVs)photogrammetry.In recent years,the utilization of UAVs for aerial photogram...The estimation of orientation parameters and correction of lens distortion are crucial problems in the field of Unmanned Aerial Vehicles(UAVs)photogrammetry.In recent years,the utilization of UAVs for aerial photogrammetry has witnessed a surge in popularity.Typically,UAVs are equipped with low-cost non-metric cameras and a Position and Orientation System(POS).Unfortunately,the Interior Orientation Parameters(IOPs)of the non-metric cameras are not fixed.Whether the lens distortions are large or small,they effect the image coordinates accordingly.Additionally,Inertial Measurement Units(IMUs)often have observation errors.To address these challenges and improve parameter estimation for UAVs Light Detection and Ranging(LiDAR)and photogrammetry,this paper analyzes the accuracy of POS observations obtained from Global Navigation Satellite System Real Time Kinematic(GNSS-RTK)and IMU data.A method that incorporates additional known conditions for parameter estimation,a series of algorithms to simultaneously solve for IOPs,Exterior Orientation Parameters(EOPs),and camera lens distortion correction parameters are proposed.Extensive experiments demonstrate that the coordinates measured by GNSS-RTK can be directly used as linear EOPs;however,angular EOP measurements from IMUs exhibit relatively large errors compared to adjustment results and require correction during the adjustment process.The IOPs of non-metric cameras vary slightly between images but need to be treated as unknown parameters in high precision applications.Furthermore,it is found that the Ebner systematic error model is sensitive to the choice of the magnification parameter of the photographic baseline length in images,it should be set as less than or equal to one third of the photographic baseline to ensure stable solutions.展开更多
Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms ...Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms remains an essential challenge in THz science and technology. To address this issue, we propose a ferromagnetic detection scheme based on Zeeman torque sampling, achieving distortion-free strong-field THz waveform detection in Py films. Thickness-dependent characterization(3–21 nm) identifies peak detection performance at 21 nm within the investigated range. Furthermore, by structurally engineering the Py ferromagnetic layer, we demonstrate strong-field THz detection in symmetric Ta(3 nm)/Py(9 nm)/Ta(3 nm) heterostructure while simultaneously resolving Zeeman torque responses and collective spin-wave dynamics in asymmetric W(4 nm)/Py(9 nm)/Pt(2 nm)heterostructure. We calculated spin wave excitations and spin orbit torque distributions in asymmetric heterostructures, along with spin wave excitations in symmetric modes. This approach overcomes the sensitivity limitations of conventional techniques in strong-field conditions.展开更多
To alleviate the distortion of XRII X-ray image intensifier images in the C-arm CT computer tomography imaging system an algorithm based on the Delaunay triangulation interpolation is proposed.First the causes of the ...To alleviate the distortion of XRII X-ray image intensifier images in the C-arm CT computer tomography imaging system an algorithm based on the Delaunay triangulation interpolation is proposed.First the causes of the phenomenon the classical correction algorithms and the Delaunay triangulation interpolation are analyzed.Then the algorithm procedure is explained using flow charts and illustrations. Finally experiments are described to demonstrate its effectiveness and feasibility. Experimental results demonstrate that the Delaunay triangulation interpolation can have the following effects.In the case of the same center the root mean square distances RMSD and standard deviation STD between the corrected image with Delaunay triangulation interpolation and the ideal image are 5.760 4 ×10 -14 and 5.354 2 ×10 -14 respectively.They increase to 1.790 3 2.388 8 2.338 8 and 1.262 0 1.268 1 1.202 6 after applying the quartic polynomial model L1 and model L2 to the distorted images respectively.The RMSDs and STDs between the corrected image with the Delaunay triangulation interpolation and the ideal image are 2.489 × 10 -13 and 2.449 8 ×10 -13 when their centers do not coincide. When the quartic polynomial model L1 and model L2 are applied to the distorted images they are 1.770 3 2.388 8 2.338 8 and 1.269 9 1.268 1 1.202 6 respectively.展开更多
The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group＇s s...The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group＇s sweep to terminate. The cycle time can be reduced drastically and hence the production efficiency can be increased significantly but harmonic distortion of one sweep will leak into the record of the other sweep. In this paper, we propose an anti-correlation method for removing harmonic distortion in vibroseis data. This method is based on decomposition of the ground force signal into fundamental and harmonic components. Then the corresponding anti-correlation operator can be computed to estimate the energy of each harmonic after correlating the vibroseis data with the corresponding harmonic component. Finally, the vibroseis harmonic noise to be removed can be obtained by subtracting the extracted harmonic noise from the traces of the previous group＇s sweep. The advantage of the proposed method is that it can process both uncorrelated and correlated vibroseis seismic data. Moreover, the algorithm is simple, stable, and computationally fast. Especially, the significant contribution of this method is a considerable reduction in the harmonic without any alteration of the desired signals. The method was tested on both synthetic and field data sets to validate the good harmonic noise suppression results.展开更多
Using a gravity anomaly covariance function based on the second-order Ganssian Markov gravity anomaly potential model, the state equation of a gravity anomaly signal is obtained in marine gravimetry. Combined with the...Using a gravity anomaly covariance function based on the second-order Ganssian Markov gravity anomaly potential model, the state equation of a gravity anomaly signal is obtained in marine gravimetry. Combined with the system state equation and the measurement equation, a new method of the cascade Kalman filter is proposed and applied to the correction of gravity anomaly distortion. In the signal processing procedure, an inverse Kalman filter is used to restore the gravity anomaly signal and high frequency noises first. Then an adaptive Kalman filter, which uses the gravity anomaly state equation as the system equation, is set to estimate the actual gravity anomaly data. Emulations and experiments indicate that both the cascade Kalman filter method and the single inverse Kalman filter method are effective in alleviating the distortion of the gravity anomaly signal, but the performance of the cascade Kalman filter method is better than that of the single inverse Kalman filter method.展开更多
According to the stationary principle of potential energy and the generalized coordinate method, a stiffness matrix of a beam element considering distortion effects is derived. Using the stiffness matrix of the beam e...According to the stationary principle of potential energy and the generalized coordinate method, a stiffness matrix of a beam element considering distortion effects is derived. Using the stiffness matrix of the beam element, a finite element program for computing thin-walled box steel beams is developed. And the program can take the section distortion and warping effects into account. The influences of diaphragm spacing on the mechanical behavior of thin-walled box beams are analyzed by the program. The numerical analysis shows that setting diaphragms have the greatest influence on the distortion normal stress, while there is very little influence on the bending normal stress. Only when the distance of adjacent diaphragms decreases to a certain value, will the distortion normal stress in the thin-walled box beam obviously reduce under the distortion load. Finally, a distortion-warping coefficient γ is introduced for simplifying the calculation of the longitudinal normal stress of thin-walled box beams. When the ratio of diaphragms adjacent space L to the maximum section dimension H is less than 2, the distortion-warping coefficient γ tends to one, which means that the distortion normal stress of the thin-walled box beam tends to zero, and the effect of the section distortion can be ignored.展开更多
Transistors are nonlinear devices, which can produce nonlinear distortion in amplifier while amplifying signals. For weak nonlinear distortion, the expressions of total harmonic distortion (THD), the second order in...Transistors are nonlinear devices, which can produce nonlinear distortion in amplifier while amplifying signals. For weak nonlinear distortion, the expressions of total harmonic distortion (THD), the second order intermodulation distortion(IM2 ), the third order intermodulation distortion(IM 3) and intercept point(IP 3) are deduced. With the aid of software Multisim, we simulate transistor common emitter amplifier, transistor common emitter amplifier with resistor in emitter, differential amplifier and differential amplifier with resistor between emitters. The simulational results and theoretical analyses are almost the same.展开更多
Distortion analysis of SOI MOS transistor is presented.By the power series method,the distortion behaviors of FD (fully depleted) and RC (recessed channel) SOI MOS transistor configurations are investigated.It is show...Distortion analysis of SOI MOS transistor is presented.By the power series method,the distortion behaviors of FD (fully depleted) and RC (recessed channel) SOI MOS transistor configurations are investigated.It is shown that the distortion figures deteriorate with the scaling down of channel length,and the RC SOI device shows better distortion performance than the FD SOI device.At the same time,the experimental data show that the ineffective body contact can lead to an increase of the harmonic amplitude due to the bulk resistance.The presented results give an intuitive knowledge for the design of low distortion mixed signal integrated system.展开更多
X-ray image has been widely used in many fields such as medical diagnosis,industrial inspection,and so on.Unfortunately,due to the physical characteristics of X-ray and imaging system,distortion of the projected image...X-ray image has been widely used in many fields such as medical diagnosis,industrial inspection,and so on.Unfortunately,due to the physical characteristics of X-ray and imaging system,distortion of the projected image will happen,which restrict the application of X-ray image,especially in high accuracy fields.Distortion correction can be performed using algorithms that can be classified as global or local according to the method used,both having specific advantages and disadvantages.In this paper,a new global method based on support vector regression（SVR）machine for distortion correction is proposed.In order to test the presented method,a calibration phantom is specially designed for this purpose.A comparison of the proposed method with the traditional global distortion correction techniques is performed.The experimental results show that the proposed correction method performs better than the traditional global one.展开更多
An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents ...An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents a small signal AlGaAs/GaAs HBT equivalent circuit, based on the DC characteristics and S parameter of the device. Using Volterra series, we have calculated the third order intermodulation distortion in a linear AlGaAs/GaAs HBT amplifier. The calculations are well concordant with the measurements from two tone signals intermodulation distortion test, and its excellent third order intermodulation performance shows that AlGaAs/GaAs HBT is a very attractive candidate for linear amplification.展开更多
文摘As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.
基金National Natural Science Foundation of China(22008166)Fundamental Research Program of Shanxi Province(202403021211029,201901D211047).
文摘The conversion of CO_(2)to dimethyl carbonate(DMC)offers a promising route for CO_(2)utilization.In this study,four CeO2 catalysts with distinct nanostructures were synthesized via a template-free hydrothermal method by systematically varying the types and concentrations of precipitants as well as the hydrothermal reaction conditions,and they were employed for DMC synthesis from CO_(2)and methanol.The atomic arrangements of CeO_(2)varied significantly with its morphology,leading to differences in lattice distortion,which directly influenced the concentration of oxygen vacancies.Notably,the CeO_(2)nanospheres,which exhibited the highest lattice distortion and oxygen vacancy concentration,achieved a DMC yield(11.12 mmol/g)48 times greater than that of the nanocubes(0.23 mmol/g).The results indicated that oxygen vacancies played a pivotal role in the catalytic process by facilitating the adsorption and activation of CO_(2)to form bidentate carbonates,as well as activating methanol to generate methoxy species.These processes collectively promoted the formation of the key intermediate(*CH3OCOO).This study proposes a strategy to enhance the oxygen vacancy concentration by increasing lattice distortion,providing valuable insights for designing high-performance CeO_(2)catalysts for DMC synthesis.
基金supported by the National Natural Science Foundation of China(623B2098,62021001,62371434)the Postdoctoral Fellowship Program of CPSF(GZC20252293)+1 种基金the China Postdoctoral Science Foundation–Anhui Joint Support Program(2024T017AH)Anhui Postdoctoral Scientific Research Program Foundation(2025A1015).
文摘Collecting amounts of distorted/clean image pairs in the real world is non-trivial,which severely limits the practical application of these supervised learning-based methods to real-world image super-resolution(RealSR).Previous works usually address this problem by leveraging unsupervised learning-based technologies to alleviate the dependency on paired training samples.However,these methods typically suffer from unsatisfactory texture synthesis due to the lack of supervision of clean images.To overcome this problem,we are the first to take a close look at the under-explored direction for RealSR,i.e.,few-shot real-world image super-resolution,which aims to tackle the challenging RealSR problem with few-shot distorted/clean image pairs.Under this brand-new scenario,we propose distortion relation guided transfer learning(DRTL)for the few-shot RealSR by transferring the rich restoration knowledge from auxiliary distortions(i.e.,synthetic distortions)to the target RealSR under the guidance of the distortion relation.Concretely,DRTL builds a knowledge graph to capture the distortion relation between auxiliary distortions and target distortion(i.e.,real distortions in RealSR).Based on the distortion relation,DRTL adopts a gradient reweighting strategy to guide the knowledge transfer process between auxiliary distortions and target distortions.In this way,DRTL is able to quickly learn the most relevant knowledge from the synthetic distortions for the target distortion.We instantiate DRTL with two commonly-used transfer learning paradigms,including pretraining and meta-learning pipelines,to realize a distortion relation-aware few-shot RealSR.Extensive experiments on multiple benchmarks and thorough ablation studies demonstrate the effectiveness of our DRTL.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074368,92165207,12474490,12034018,and 92265113)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302300)+1 种基金the USTC Tang Scholarshippartially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication。
文摘In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line.Both methods are straightforward to implement,robust against noise,and applicable to a wide range of qubit types.The two methods differ in correction accuracy and complexity.The first,coarse predistortion(CPD)method,partially mitigates distortion.The second,all predistortion(APD)method,measures the transfer function and significantly enhances exchange oscillation uniformity.Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse.We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.
基金supported in part by the National Natural Science Foundation of China(Nos.61873196,62373030,61772187)the Innovation Program for Quantum Science and Technology(No.2021ZD0303400)。
文摘The traditional orbit determination method based on pulsar profile distortion can determine the six elements of the orbit.However,the estimation accuracies of these methods are limited and the computational load of a six-dimensional search is huge.To solve this problem,the differential-geometry-based Multi-dimensional Joint Position-Velocity Estimation(MJPVE)using Crab pulsar profile distortion is proposed in this paper.Firstly,through theoretical analysis,it is found that the pulsar profile distortion caused by the initial state error in some joint positionvelocity directions is very small.In other words,the accuracies of estimation in these directions are very low.Namely,the search dimension can be reduced,which in turn greatly reduces the computational load.Then,we construct the chi-squared function of the pulsar profile with respect to the estimation error in joint position-velocity direction and use differential geometry to find the joint position-velocity directions corresponding to different degrees of distortion.Finally,we utilize the grid search based on directory folding in these joint position-velocity directions corresponding to large degrees of distortion to obtain the joint position-velocity estimation.The experimental results show that compared with the grouping bi-chi-squared inversion method,MJPVE has high precision and extensive navigation information.
文摘Fe-N-C catalysts are promising substitutes for precious-metal platinum in acidic oxygen reduction reactions(ORR),yet their moderate intrinsic activity and susceptibility to reactive oxygen species(ROS)-induced degradation hinder practical implementation.Herein,we fabricate a Ru-Fe dual-site catalyst(RuFe-N-C)through a two-step pyrolysis strategy.Structural characterization reveals atomic-scale proximity between Ru single atoms and Fe-N_(4) moieties,exhibiting a projected distance of~1.7Å.This configuration induces Fe–N bond elongation accompanied by 2.5%lattice distortion.The optimized RuFe-N-C catalyst exhibits high ORR performance,with a half-wave potential(E_(1/2))of 0.840 V and peak power density(P_(max))of 938 mW cm^(-2) under 150 kPa absolute H_(2)-O_(2).These metrics signify substantial enhancements relative to conventional Fe-N-C benchmarks(+21 mV in E_(1/2) and+42%in P_(max)).Moreover,the catalyst maintains outstanding stability,showing merely 17 mV E_(1/2) decay after 10000 accelerated durability test(ADT)cycles.Experimental analyses reveal a bifunctional mechanism:(1)Adjacent Ru sites substantially enhance the intrinsic ORR activity of Fe-N_(4) moieties,delivering a notable turnover frequency(TOF=17.86 e site^(-1) s^(-1) at 0.85 V vs.RHE)that exceeds state-of-the-art Fe-N-C benchmarks by 1-2 orders of magnitude(<1 e site^(-1) s^(-1));(2)Ru centers function as electron relays that facilitate ROS scavenging,thus suppressing degradation.This work establishes a paradigm for engineering bimetallic single-atom catalysts through synergistic electronic modulation to concurrently enhance activity and stability.
基金supported by the National Natural Science Foundation of China under Grant No.21933006.
文摘To eliminate distortion caused by vertical drift and illusory slopes in atomic force microscopy(AFM)imaging,a lifting-wavelet-based iterative thresholding correction method is proposed in this paper.This method achieves high-quality AFM imaging via line-by-line corrections for each distorted profile along the fast axis.The key to this line-by-line correction is to accurately simulate the profile distortion of each scanning row.Therefore,a data preprocessing approach is first developed to roughly filter out most of the height data that impairs the accuracy of distortion modeling.This process is implemented through an internal double-screening mechanism.A line-fitting method is adopted to preliminarily screen out the obvious specimens.Lifting wavelet analysis is then carried out to identify the base parts that are mistakenly filtered out as specimens so as to preserve most of the base profiles and provide a good basis for further distortion modeling.Next,an iterative thresholding algorithm is developed to precisely simulate the profile distortion.By utilizing the roughly screened base profile,the optimal threshold,which is used to screen out the pure bases suitable for distortion modeling,is determined through iteration with a specified error rule.On this basis,the profile distortion is accurately modeled through line fitting on the finely screened base data,and the correction is implemented by subtracting the modeling result from the distorted profile.Finally,the effectiveness of the proposed method is verified through experiments and applications.
基金Financial support from the National Natural Science Foundation of China(grant no.U20A20154,22279005,22379006,21575016)the National Program for Support of Top-notch Young Professionals is gratefully acknowledgedtechnical support from the Xi’an Advanced Computing Center
文摘Jahn-Teller distortion(JTD)remains a fundamental bottleneck for transition metal oxides(TMOs)in electrochemical energy storage,where the e_(g)-orbital single-electron occupancy induces irreversible octahedral collapse and rapid capacity fading.Here,we pioneer an itinerant-electron-mediated dynamic suppression strategy that fundamentally reshapes the JTD evolution pathway throughπ-d orbital hybridization engineering.By constructing reduced graphene oxide/TMO heterointerfaces(rGO/MO_(x),M=Fe/Ni/Mn),localized 3d electrons are transformed into delocalized itinerant states,which(1)eliminate e_(g)-band degeneracy via orbital repopulation and(2)establish an electron density buffer layer to neutralize lattice strain.This electronic regulation enables ultrafast Na^(+)diffusion kinetics(508.3 F g^(−1)at 1 A g^(−1)→304.6 F g^(−1)at 20 A g^(−1))and near-zero lattice deformation(91.07%capacitance retention after 20,000 cycles).Synchrotron-based X-ray absorption spectroscopy and density functional theory calculations reveal that itinerant electron dynamics actively decouple the Mn^(3+)d^(4)electronic configuration from JTD triggering,leading to a dramatic suppression of octahedral distortion compared to the conventional MnO_(2).The proposed electron delocalization-to-lattice stabilization paradigm opens a universal route to design distortion-resistant electrodes for high-power energy storage systems.
基金financially supported by the National Natural Science Foundation of China(Nos.22471289,22478430,22101300,and 22275210)Shandong Natural Science Foundation(Nos.ZR2022ME105 and ZR2023ME004)+1 种基金Qingdao Natural Science Foundation(No.23-2-1-232-zyyd-jch)the Fundamental Research Funds for the Central Universities(Nos.22CX03010A,and 22CX01002A-1).
文摘Efficient and stable electrocatalysts are essential for seawater splitting to sustain electrolysis without chloride corrosion,particularly at the anode.Furthermore,the oxygen evolution reaction(OER)requires high overpotential due to the universal scaling relationship.Herein,molybdenum doping FeNi_(2)Se_(4)with lattice distortion is proposed to break the scaling relationship.Mo-FeNi_(2)Se_(4)shows high performance in direct seawater electrolysis and achieves current densities of 10 and 100 mA cm^(−2) at overpotentials of 190 and 250 mV,respectively,together with high OER selectivity and long-term stability.It is found that the lattice distortion induced by Mo doping in(3 1 0)plane of FeNi_(2)Se_(4),leads to a decrease in the d-band center and the adsorption energy of ^(*)O,which not only breaks the scaling relationship of OER but also lowers the energy barriers of rate-determining step.Moreover,it enhances the corrosion resistance to Cl^(−),and realizes the high-efficiency seawater electrolysis driven by photovoltaic.
基金Natural Science Foundation of Hunan Province,China(No.2024JJ8335)Open Topic of Hunan Geospatial Information Engineering and Technology Research Center,China(No.HNGIET2023004).
文摘The estimation of orientation parameters and correction of lens distortion are crucial problems in the field of Unmanned Aerial Vehicles(UAVs)photogrammetry.In recent years,the utilization of UAVs for aerial photogrammetry has witnessed a surge in popularity.Typically,UAVs are equipped with low-cost non-metric cameras and a Position and Orientation System(POS).Unfortunately,the Interior Orientation Parameters(IOPs)of the non-metric cameras are not fixed.Whether the lens distortions are large or small,they effect the image coordinates accordingly.Additionally,Inertial Measurement Units(IMUs)often have observation errors.To address these challenges and improve parameter estimation for UAVs Light Detection and Ranging(LiDAR)and photogrammetry,this paper analyzes the accuracy of POS observations obtained from Global Navigation Satellite System Real Time Kinematic(GNSS-RTK)and IMU data.A method that incorporates additional known conditions for parameter estimation,a series of algorithms to simultaneously solve for IOPs,Exterior Orientation Parameters(EOPs),and camera lens distortion correction parameters are proposed.Extensive experiments demonstrate that the coordinates measured by GNSS-RTK can be directly used as linear EOPs;however,angular EOP measurements from IMUs exhibit relatively large errors compared to adjustment results and require correction during the adjustment process.The IOPs of non-metric cameras vary slightly between images but need to be treated as unknown parameters in high precision applications.Furthermore,it is found that the Ebner systematic error model is sensitive to the choice of the magnification parameter of the photographic baseline length in images,it should be set as less than or equal to one third of the photographic baseline to ensure stable solutions.
基金supported by the Scientific Research Innovation Capability Support Project for Young Faculty (Grant No.ZYGXQNJSKYCXNLZCXMI3)the National Key Research and Development Program of China (Grant No.2022YFA1604402)+1 种基金the National Natural Science Foundation of China (Grant Nos.U23A6002,92250307,and 52225106)the Beijing Municipal Science and Technology Commission,Administrative Commission of Zhongguancun Science Park (Grant No.Z25110000692500)。
文摘Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms remains an essential challenge in THz science and technology. To address this issue, we propose a ferromagnetic detection scheme based on Zeeman torque sampling, achieving distortion-free strong-field THz waveform detection in Py films. Thickness-dependent characterization(3–21 nm) identifies peak detection performance at 21 nm within the investigated range. Furthermore, by structurally engineering the Py ferromagnetic layer, we demonstrate strong-field THz detection in symmetric Ta(3 nm)/Py(9 nm)/Ta(3 nm) heterostructure while simultaneously resolving Zeeman torque responses and collective spin-wave dynamics in asymmetric W(4 nm)/Py(9 nm)/Pt(2 nm)heterostructure. We calculated spin wave excitations and spin orbit torque distributions in asymmetric heterostructures, along with spin wave excitations in symmetric modes. This approach overcomes the sensitivity limitations of conventional techniques in strong-field conditions.
基金The Natural Science Foundation of Anhui Province(No.1308085MF96)the Project of Chuzhou University(No.2012qd06,2011kj010B)+1 种基金the Scientific Research Foundation of Education Department of Anhui Province(No.KJ2014A186)the National Basic Research Program of China(973 Program)(No.2010CB732503)
文摘To alleviate the distortion of XRII X-ray image intensifier images in the C-arm CT computer tomography imaging system an algorithm based on the Delaunay triangulation interpolation is proposed.First the causes of the phenomenon the classical correction algorithms and the Delaunay triangulation interpolation are analyzed.Then the algorithm procedure is explained using flow charts and illustrations. Finally experiments are described to demonstrate its effectiveness and feasibility. Experimental results demonstrate that the Delaunay triangulation interpolation can have the following effects.In the case of the same center the root mean square distances RMSD and standard deviation STD between the corrected image with Delaunay triangulation interpolation and the ideal image are 5.760 4 ×10 -14 and 5.354 2 ×10 -14 respectively.They increase to 1.790 3 2.388 8 2.338 8 and 1.262 0 1.268 1 1.202 6 after applying the quartic polynomial model L1 and model L2 to the distorted images respectively.The RMSDs and STDs between the corrected image with the Delaunay triangulation interpolation and the ideal image are 2.489 × 10 -13 and 2.449 8 ×10 -13 when their centers do not coincide. When the quartic polynomial model L1 and model L2 are applied to the distorted images they are 1.770 3 2.388 8 2.338 8 and 1.269 9 1.268 1 1.202 6 respectively.
基金supported by the Sinopec Service Company and China National Petroleum Corporation
文摘The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group＇s sweep to terminate. The cycle time can be reduced drastically and hence the production efficiency can be increased significantly but harmonic distortion of one sweep will leak into the record of the other sweep. In this paper, we propose an anti-correlation method for removing harmonic distortion in vibroseis data. This method is based on decomposition of the ground force signal into fundamental and harmonic components. Then the corresponding anti-correlation operator can be computed to estimate the energy of each harmonic after correlating the vibroseis data with the corresponding harmonic component. Finally, the vibroseis harmonic noise to be removed can be obtained by subtracting the extracted harmonic noise from the traces of the previous group＇s sweep. The advantage of the proposed method is that it can process both uncorrelated and correlated vibroseis seismic data. Moreover, the algorithm is simple, stable, and computationally fast. Especially, the significant contribution of this method is a considerable reduction in the harmonic without any alteration of the desired signals. The method was tested on both synthetic and field data sets to validate the good harmonic noise suppression results.
基金Pre-Research Program of General Armament Departmentduring the 11th Five-Year Plan Period(No.51309010201)the National Natural Science Foundation of China(No.60575010)
文摘Using a gravity anomaly covariance function based on the second-order Ganssian Markov gravity anomaly potential model, the state equation of a gravity anomaly signal is obtained in marine gravimetry. Combined with the system state equation and the measurement equation, a new method of the cascade Kalman filter is proposed and applied to the correction of gravity anomaly distortion. In the signal processing procedure, an inverse Kalman filter is used to restore the gravity anomaly signal and high frequency noises first. Then an adaptive Kalman filter, which uses the gravity anomaly state equation as the system equation, is set to estimate the actual gravity anomaly data. Emulations and experiments indicate that both the cascade Kalman filter method and the single inverse Kalman filter method are effective in alleviating the distortion of the gravity anomaly signal, but the performance of the cascade Kalman filter method is better than that of the single inverse Kalman filter method.
基金Specialized Research Fund for the Doctoral Program of Higher Education (No.20070247002)
文摘According to the stationary principle of potential energy and the generalized coordinate method, a stiffness matrix of a beam element considering distortion effects is derived. Using the stiffness matrix of the beam element, a finite element program for computing thin-walled box steel beams is developed. And the program can take the section distortion and warping effects into account. The influences of diaphragm spacing on the mechanical behavior of thin-walled box beams are analyzed by the program. The numerical analysis shows that setting diaphragms have the greatest influence on the distortion normal stress, while there is very little influence on the bending normal stress. Only when the distance of adjacent diaphragms decreases to a certain value, will the distortion normal stress in the thin-walled box beam obviously reduce under the distortion load. Finally, a distortion-warping coefficient γ is introduced for simplifying the calculation of the longitudinal normal stress of thin-walled box beams. When the ratio of diaphragms adjacent space L to the maximum section dimension H is less than 2, the distortion-warping coefficient γ tends to one, which means that the distortion normal stress of the thin-walled box beam tends to zero, and the effect of the section distortion can be ignored.
文摘Transistors are nonlinear devices, which can produce nonlinear distortion in amplifier while amplifying signals. For weak nonlinear distortion, the expressions of total harmonic distortion (THD), the second order intermodulation distortion(IM2 ), the third order intermodulation distortion(IM 3) and intercept point(IP 3) are deduced. With the aid of software Multisim, we simulate transistor common emitter amplifier, transistor common emitter amplifier with resistor in emitter, differential amplifier and differential amplifier with resistor between emitters. The simulational results and theoretical analyses are almost the same.
文摘Distortion analysis of SOI MOS transistor is presented.By the power series method,the distortion behaviors of FD (fully depleted) and RC (recessed channel) SOI MOS transistor configurations are investigated.It is shown that the distortion figures deteriorate with the scaling down of channel length,and the RC SOI device shows better distortion performance than the FD SOI device.At the same time,the experimental data show that the ineffective body contact can lead to an increase of the harmonic amplitude due to the bulk resistance.The presented results give an intuitive knowledge for the design of low distortion mixed signal integrated system.
基金National Natural Science Foundation of China(No.61305118)
文摘X-ray image has been widely used in many fields such as medical diagnosis,industrial inspection,and so on.Unfortunately,due to the physical characteristics of X-ray and imaging system,distortion of the projected image will happen,which restrict the application of X-ray image,especially in high accuracy fields.Distortion correction can be performed using algorithms that can be classified as global or local according to the method used,both having specific advantages and disadvantages.In this paper,a new global method based on support vector regression（SVR）machine for distortion correction is proposed.In order to test the presented method,a calibration phantom is specially designed for this purpose.A comparison of the proposed method with the traditional global distortion correction techniques is performed.The experimental results show that the proposed correction method performs better than the traditional global one.
文摘An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents a small signal AlGaAs/GaAs HBT equivalent circuit, based on the DC characteristics and S parameter of the device. Using Volterra series, we have calculated the third order intermodulation distortion in a linear AlGaAs/GaAs HBT amplifier. The calculations are well concordant with the measurements from two tone signals intermodulation distortion test, and its excellent third order intermodulation performance shows that AlGaAs/GaAs HBT is a very attractive candidate for linear amplification.
