In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused...In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused byαparticle ionizing radiation was proposed,and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions.The experimental results show thatαparticle response signal has highest accuracy at 9 dB gain,with an obvious“target-ring”distribution.With increasing cumulative dose,the CMOS APS pedestal tends to saturation while dead pixels continue increasing.Though some pixel damage recovers through natural annealing,the dead-to-noise ratio increases with irradiation time,reaching 32.54%after 72 h.A hierarchical clustering dead-pixel detection method is proposed,categorizing pixels into two types:those within and outside the response event.A classification compensation strategy combining mean and majority filtering is proposed.This compensation algorithm can address dead-pixel interference without affectingαparticle radiation response data.When iterated multiple times and with integration time exceeding 6.31 ms,the number of dead pixels can be effectively reduced.展开更多
Urbanization alters vegetation productivity by both direct(ωd)and indirect(ω_(i))effects.The direct effect is from the change of vegetated area indicated by impervious surface intensity(ISI),while indirect effects a...Urbanization alters vegetation productivity by both direct(ωd)and indirect(ω_(i))effects.The direct effect is from the change of vegetated area indicated by impervious surface intensity(ISI),while indirect effects arise from changes in urban environmental factors,such as near-surface air temperatures,precipitation,urban heat island(UHI)intensity,and population density(POP).The respective contributions ofω_(d) andω_(i) to vegetation net primary productivity(NPP)under various phases of urbanization are not well quantified.Using multisource remote-sensing data from 1990 to 2020,we analyzed the spatiotemporal variation in urban expansion and the effect thatω_(d) andω_(i) had on NPP in the megalopolis of Beijing,China,over 5-year intervals.During this period,Beijing underwent significant planar expansion rates of about 58.9 km^(2)/yr.Annual mean loss of NPP byω_(d) was estimated to be about 77.1 g C/(m^(2)·yr)during the 1990-2020 period,while annual mean improvement to NPP byω_(i) amounted to an increase of 28.9 g C/(m^(2)·yr).The NPP losses were partially offset by NPP improvements in the order of 18.6%-69.3%.The impact of forcing variables on NPP varied spatially.Air temperature,precipitation,UHI,POP,and ISI explained about 13.8%,23.2%,23.7%,14.7%,and 24.6%of the spatial variation in NPP.The impact of air temperature on NPP was related to available moisture,negatively affecting NPP in regions with water deficits.Our findings demonstrate the dual impact of urbanization on vegetation and underscore the necessity for spatially adaptive ecological management strategies in regions experiencing rapid urban growth.展开更多
Measuring cross sections of nuclear reactions,such as the so-called“Holy Grail”reaction,^(12)C(σ,γ)^(16)O,is essential for understanding stellar nucleosynthesis but presents significant challenges due to extremely...Measuring cross sections of nuclear reactions,such as the so-called“Holy Grail”reaction,^(12)C(σ,γ)^(16)O,is essential for understanding stellar nucleosynthesis but presents significant challenges due to extremely low cross sections.Key challenges include significant energy loss as ions penetrate the target material,limiting measurements to thin target layers.To overcome these obstacles,we propose a novel method,the in-target energy loss compensating(eLOC)method,specifically designed for gas targets,which utilizes a gas-filled magnetic field and accelerating electric fields to compensate for ion energy loss in the target.Simulations show that this approach significantly enhances the effective target thickness by over 140 times in the case of the“Holy Grail”reaction with an inverse-kinematics setup.This eLOC method may provide a powerful new tool for obtaining critical data in nuclear astrophysics,thereby advancing our understanding of stellar nucleosynthesis and the origins of elements in the universe,as well as benefiting other related fields such as isotope production.展开更多
The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestratio...The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestration in grasslands remains unclear.Based on panel data from prefecture-level cities in the Yellow River Basin(YRB)from 2000 to 2020,this study explored the effects of the GECP on grassland carbon sequestration in the YRB and its heterogeneity using a time-varying difference-in-differences(TV-DID)model.Subsequently,we predicted changes in carbon sequestration in grasslands under the influence of the GECP from 2021 to 2040 using a simulation.The main conclusions are as follows:First,the implementation of the GECP promoted carbon sequestration in grasslands.This conclusion was validated after conducting a series of robustness tests.Moreover,the effects of the GECP were heterogeneous across different geographical locations,highway densities,and grassland areas.Finally,the simulation results indicated that over the next 20 years,grassland carbon sequestration will generally increase but exhibit cyclical changes.The government should align the principles and objectives of the GECP with local geographic conditions,resource availability,and socio-economic development.It must formulate and implement tailored policies that maximize the ecological protection benefits of the GECP and promote carbon sequestration in the grasslands of the YRB.展开更多
This study aims to explore how the Wei River Basin can enhance the efficiency of horizontal ecological compensation to promote high-quality and sustainable development in the Yellow River Basin.To achieve this,a four-...This study aims to explore how the Wei River Basin can enhance the efficiency of horizontal ecological compensation to promote high-quality and sustainable development in the Yellow River Basin.To achieve this,a four-stage DEA(Data Envelopment Analysis)method was employed to evaluate the efficiency of ecological compensation in six prefecture-level cities within the Wei River Basin from 2001 to 2022.In addition,the K-prototype clustering analysis method was integrated to assess the regional differences in ECE(ecological compensation efficiency).The findings indicate:(1)the ecological compensation efficiency in the upstream areas of the Wei River Basin is significantly higher than in the downstream regions;(2)the influence of factors such as the proportion of the tertiary industry,population density and residents’disposable income on the efficiency of ecological compensation is significant;(3)after excluding environmental factors,the overall ecological compensation efficiency showed a significant improvement.Based on these insights,it is recommended that the provinces of Shaanxi and Gansu further establish a robust compensation fund operation mechanism,build a cross-regional ecological compensation upstream-downstream coordination system,and strengthen inter-basin economic cooperation mechanisms to promote dual-driven development through technological advancement and scale benefits,thereby advancing ecological protection and sustainable development in the Wei River Basin.展开更多
In an ultraprecision turning process for small-diameter optical aspheric workpieces,tool-profile errors induce mid-frequency errors in the workpiece profile,limiting further improvements in precision.In this study,an ...In an ultraprecision turning process for small-diameter optical aspheric workpieces,tool-profile errors induce mid-frequency errors in the workpiece profile,limiting further improvements in precision.In this study,an XZB three-axis linkage ultraprecision machining method is proposed,and the effects of tool-center errors are analyzed.To address residual errors in Z-direction profile-error compensation,a workpiece normal-profile-error compensation method is proposed.After XZB three-axis linkage turning and compensation,the workpiece profile error(PV)reaches 0.086μm,surpassing the precision of XZ two-axis machining,and mid-frequency errors are reduced.Compared with Z-direction profile-error compensation,which results in a profile error of 0.092μm,normal-profile-error compensation reduces PV to 0.047μm,considerably improving aspheric accuracy.Experimental results demonstrate that XZB three-axis linkage machining significantly improves the aspheric workpiece profile,enhancing both its accuracy and surface quality.This method reduces mid-frequency errors,and the subsequent application of normal-profile-error compensation further refines the profile,achieving higher overall accuracy.展开更多
Thermal errors in CNC machine tools,particularly those involving the spindle,significantly affect machining accuracy and performance.These errors,caused by temperature fluctuations in the spindle and surrounding compo...Thermal errors in CNC machine tools,particularly those involving the spindle,significantly affect machining accuracy and performance.These errors,caused by temperature fluctuations in the spindle and surrounding components,result in dimensional deviations that can lead to poor part quality and reduced precision in high-speed manufacturing processes.This paper explores thermal error modeling and compensation methods for the spindle of five-axis CNC machine tools.A detailed analysis of the heat generation,transfer mechanisms,and finite element analysis(FEA)is presented to develop accurate thermal error models.Compensation techniques,such as model-based methods,sensor-based methods,real-time compensation algorithms,and hybrid approaches,are critically reviewed.This study also discusses the challenges in real-time compensation and the integration of thermal error compensation with machine tool control systems.The objective is to provide a comprehensive understanding of thermal error phenomena and their compensation strategies,ultimately contributing to the enhancement of machining accuracy in advanced manufacturing applications.展开更多
Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed...Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed solution in the dual-wavelength spectral method based on the Lambert-Beer law additive principle.It compensates for the influence of turbidity on the absorption coefficient of the COD solution at 355 nm by the absorption spectrum coefficient of the mixed solution at 623 nm.This paper establishes a linear relationship model between the absorbance difference of the mixed solution at 355 nm and 623 nm and COD.The experimental determination coefficient R2 of the model is 0.98335,with a relative error of 3.5%and an average error of 0.7 mg/L.The design of the model is simple and easy to systematize,which is of strong significance for practical application.展开更多
The Hydro-Viscous Drive(HVD)speed regulating system finds extensive application in air transport transmission systems to regulate the stepless speed or conduct overload protection.However,its intrinsic hysteretic beha...The Hydro-Viscous Drive(HVD)speed regulating system finds extensive application in air transport transmission systems to regulate the stepless speed or conduct overload protection.However,its intrinsic hysteretic behaviors,such as the asymmetric hysteretic and dead zone,could introduce inaccuracy and delay in control applications,posing challenges to system regulation.This paper investigates a Nonlinear Hysteresis Compensation Control(NHCC)that consists of two parts to control the HVD output speed by operating the valve under different engine operating conditions.In the first part,the Inverse Hysteresis Compensator(IHC)based on major loop data is introduced for the asymmetric hysteresis characterization and compensation of the HVD speed control system of the power generation and distribution,which aims to reduce the hysteresis and dead zone effect and expand the effective input range.In the second part,the Active Disturbance Rejection Controller(ADRC)is employed to mitigate the hysteresis effects of the compensated system and remove the steady-state error,which allows real-time compensation of the estimated perturbations as state feedback to achieve the required performance.An experimental laboratory station has been fabricated to evaluate the proposed method.The test results show that the NHCC method can regulate the fan speed to the desired value(45 r/min at steady state)and broaden the effective input range to the full range under different engine conditions.Besides,the proposed control method can reduce the non-linearity of the input and output curves(from 18%to 4%)and compensate for the asymmetric hysteresis(from 38%to 5%).展开更多
To address the issue of disturbance compensation deviation in linear active disturbance rejection control(LADRC),a linear active disturbance rejection control method with reference to the integral chain model(LADRC-R)...To address the issue of disturbance compensation deviation in linear active disturbance rejection control(LADRC),a linear active disturbance rejection control method with reference to the integral chain model(LADRC-R)is proposed.By constructing an ideal control reference model,a dynamic correlation between output deviation and uncompensated disturbances is established,and a dual-loop compensation mechanism is designed.Based on theoretical analysis and frequency-domain characteristics of typical first/second-order systems,this method maintains the parameter-tuning advantages of LADRC while reducing disturbance effects by 50%and introducing no phase lag during low-frequency disturbance suppression.Simulations on second-order systems verify its robustness under parameter perturbations,gain mismatch,and complex disturbances,and an optimized design scheme for the deviation compensator is proposed to suppress discontinuous measurement noise interference.Finally,the engineering effectiveness of this method in precision motion control is validated on an electromagnetic suspension platform,providing a new approach to improving the control performance of LADRC in environments with uncertain disturbances.展开更多
Hard carbon(HC)is widely used in sodium-ion batteries(SIBs),but its performance has always been limited by lowinitial Coulombic efficiency(ICE)and cycling stability.Cathode compensation agent is a favorable strategy t...Hard carbon(HC)is widely used in sodium-ion batteries(SIBs),but its performance has always been limited by lowinitial Coulombic efficiency(ICE)and cycling stability.Cathode compensation agent is a favorable strategy to make up for the loss of active sodium ions consumed byHCanode.Yet it lacks agent that effectively decomposes to increase the active sodium ions as well as regulate carbon defects for decreasing the irreversible sodium ions consumption.Here,we propose 1,2-dihydroxybenzene Na salt(NaDB)as a cathode compensation agent with high specific capacity(347.9 mAh g^(-1)),lower desodiation potential(2.4–2.8 V)and high utilization(99%).Meanwhile,its byproduct could functionalize HC with more C=O groups and promote its reversible capacity.Consequently,the presodiation hard carbon(pHC)anode exhibits highly reversible capacity of 204.7 mAh g^(-1) with 98%retention at 5 C rate over 1000 cycles.Moreover,with 5 wt%NaDB initially coated on the Na3V2(PO4)3(NVP)cathode,the capacity retention of NVP + NaDB|HC cell could increase from 22%to 89%after 1000 cycles at 1 C rate.This work provides a new avenue to improve reversible capacity and cycling performance of SIBs through designing functional cathode compensation agent.展开更多
The complex working environment of distribution networks tends to cause impermanent single-phase-to-ground(SPG)fault,and high-temperature ground fault arc is prone to endanger lives and power equipment,resulting in la...The complex working environment of distribution networks tends to cause impermanent single-phase-to-ground(SPG)fault,and high-temperature ground fault arc is prone to endanger lives and power equipment,resulting in large-scale power outages and fire accidents.Thus,fault arc should be extinguished in time.Meanwhile,stable operation conditions of distribution networks and reliable load power supply should be guaranteed to provide high-quality customer service.This paper proposes an active mitigation strategy for SPG fault,and provide active and reactive power compensation at the same time by utilizing an improved flexible power electronic equipment(FPEE)with dc-link sources.These controls are decoupled from each other,so utilization of FPEE is maximized as much as possible.When a SPG fault occurs in distribution networks,FPEE can output,simultaneously,active power,reactive power,and SPG fault compensation current by controlling output current on the d,q,0 coordinate system,respectively.During normal operation of distribution networks,the FPEE can be used as a virtual synchronous generator to compensate load power and its fluctuation.The proposed simultaneous multi-function can also be applied in other cases.Simulation cases are implemented to verify principles and practicability.展开更多
The horizontal ecological compensation plays an important role in balancing the interests of all parties and coordinating regional development in the basin.However,the mechanism of ecological compensation based on emb...The horizontal ecological compensation plays an important role in balancing the interests of all parties and coordinating regional development in the basin.However,the mechanism of ecological compensation based on embodied carbon emissions is still poorly understood.Here,taking the Yellow River Basin as the research area,we use the multi-regional input-output(MRIO)model to measure the embodied carbon transfers between its seven urban agglomerations in 2012 and 2017 from the viewpoint of value-added trade benefits.Further,for the first time,the green trade benefits and ecological compensation amounts are analyzed.The results indicate that:(1)The transfer of trade-embodied carbon among the urban agglomerations in the basin showed obvious spatial heterogeneity and geographic proximity effects,and trade-embodied carbon outflows(inflows)had a pattern of"highest in the midstream,second in the downstream,and lowest in the upstream".(2)The industry composition of the urban agglomerations in relation to embodied carbon outflows(inflows)was similar,mainly in the service and heavy manufacturing industries.(3)The spatial pattern of green trade benefits in the basin had shifted from"high in the north and low in the surrounding area"to"high in the east-central part and low in the west".(4)The pattern of ecological compensation in the basin had shifted from the upstream surplus,the middle and downstream deficit to the midstream deficit,and the upstream and downstream surplus.Therefore,we recommend improving energy structures in high-demand urban agglomerations by adopting clean energy,focusing on decarbonization and energy efficiency in resource-rich regions.Additionally,promoting low-carbon economies,especially in the service and heavy manufacturing industries,implementing differentiated emission reduction strategies,and optimizing carbon compensation mechanisms considering regional disparities and resource endowments are crucial.It is expected that the study can enrich the scientific basis of horizontal ecological compensation and increase the fairness of regional carbon emission rights allocation.展开更多
Tetravalent tin(Sn^(4+))-based inorganic perovskite semiconductors like Cs_(2)SnI_(6)are expected to replace lead-based perovskite counterparts due to advantages such as structural stability and environmental friendli...Tetravalent tin(Sn^(4+))-based inorganic perovskite semiconductors like Cs_(2)SnI_(6)are expected to replace lead-based perovskite counterparts due to advantages such as structural stability and environmental friendliness.In this paper,we reported the dopant compensation effect in the component-dependent self-doped(111)-oriented Cs_(2)SnI_(6)thin films grown with pulsed laser deposition(PLD)at room temperature.The films were grown on(100)-SrTiO_(3)(STO)substrates at room temperature by PLD.Hall results of the Cs_(2)SnI_(6)films with different components realizing by controlling the ratio of SnI_(4)/CsI in the targets demonstrate a clear change of conductivity type from N-type to P-type,while the carrier concentration decreases from 1018 to 1013 and accordingly the film resistivity increases significantly from 3.8 to 2506Ωcm.The defect-relatedopticalfingerprints of Cs_(2)SnI_(6)films werealsoinvestigated withtemperature-dependent photoluminescence spectroscopy.At low temperatures of 10 K,the Cs_(2)SnI_(6)films exhibit donor-bound(D^(0)X)and donor-acceptor pair(DAP)emission,respectively,due to the self-doping effect.These re-sults indicate that controlling the composition of the PLD target is a powerful way to tune the electrical properties of Cs_(2)SnI_(6)films for possible applications in solar cells or X-ray detectors.展开更多
On the basis of analysis of the present situation of the ecological benefit compensation in China and foreign countries, this paper discusses the necessity, principle and approach of establishing the compensation mech...On the basis of analysis of the present situation of the ecological benefit compensation in China and foreign countries, this paper discusses the necessity, principle and approach of establishing the compensation mechanism of forest ecological benefit, as well as compensation standard in order to provide scientific basis for further perfecting the compensation mechanism of forest ecological engineering benefit in China. It is suggested that setting up the compensation mechanism of forest ecological benefit can not only provide the steady funds source of managing and protecting forest resources, but resolve radically the dynamic and mechanism problems of commonweal forest ecological engineering construction, which will produce a widespread and profound influence on China forestry and ecological construction.展开更多
In this paper,we investigate the method of compensating LTS SQUID Gradiometer Systems data.By matching the attitude changes of the pod in fl ight to the anomalies of the magnetic measurement data,we find that the yaw ...In this paper,we investigate the method of compensating LTS SQUID Gradiometer Systems data.By matching the attitude changes of the pod in fl ight to the anomalies of the magnetic measurement data,we find that the yaw attitude changes most dramatically and corresponds best to the magnetic data anomaly interval.Based on this finding,we solved the compensation model using least squares fitting and Huber's parametric fitting.By comparison,we found that the Huber parametric fit not only eliminates the interference introduced by attitude changes but also retains richer anomaly source information and therefore obtains a higher signal-to-noise ratio.The experimental results show that the quality of the magnetometry data obtained by using the compensation method proposed in this paper has been significantly improved,and the mean value of its improvement ratio can reach 118.93.展开更多
Industrial robots are integral to modern manufacturing systems,enabling high precision,high throughput,and flexibility.However,errors in accuracy and repeatability,which arise from a variety of sources such as mechani...Industrial robots are integral to modern manufacturing systems,enabling high precision,high throughput,and flexibility.However,errors in accuracy and repeatability,which arise from a variety of sources such as mechanical wear,calibration issues,and environmental factors,can significantly impact the performance of industrial robots.This paper aims to explore the theoretical modeling of errors in industrial robot systems and propose compensation strategies to enhance their accuracy and repeatability.Key factors contributing to errors,such as kinematic,dynamic,and environmental influences,are discussed in detail.Additionally,the paper explores various compensation techniques,including geometric error compensation,dynamic compensation,and adaptive control approaches.Through the integration of error modeling and compensation methods,industrial robots can achieve improved performance,ensuring higher operational efficiency and product quality.The paper concludes by highlighting the challenges and future research directions for improving the accuracy and repeatability of industrial robots in practical applications.展开更多
This study aimed to identify and compensate for the geometric errors of the double swiveling axes in a five-axis computer numerical control(CNC)machining center.Hence,a three-dimensional coordinate calculation algorit...This study aimed to identify and compensate for the geometric errors of the double swiveling axes in a five-axis computer numerical control(CNC)machining center.Hence,a three-dimensional coordinate calculation algorithm for a measured point with additional rotational rigid body motion constraints is proposed.The motion constraints of the rotational rigid body were analyzed,and a mathematical model of the measured point algorithm in the swiveling axes was established.The Levenberg-Marquard method was used to solve the nonlinear superstatically determined equations.The spatial coordinate error was used to separate the spatial deviation of the measured point.An identification model of the position-independent and position-dependent geometric errors was established.The three-dimensional coordinate-solving algorithm of the measured point in the swiveling axis and geometric error identification method based on the Monte Carlo method were analyzed numerically.Geometric error measurement and cutting experiments were performed on a VMC25100U five-axis machining center,which integrated two swiveling axes.Geometric errors of the A-and B-axes were identified and measured experimentally.The angular positioning errors before and after compensation were measured using a laser interferometer,which verified the effectiveness of the proposed algorithm.A cutting experiment of a round table part was performed.The shape and position accuracy of the processed part before and after compensation were detected using a coordinate measuring machine.It verified that the geometric error of the swiveling axis was effectively compensated by the algorithm proposed herein.展开更多
Absorption compensation is a process involving the exponential amplification of reflection amplitudes.This process amplifies the seismic signal and noise,thereby substantially reducing the signal-tonoise ratio of seis...Absorption compensation is a process involving the exponential amplification of reflection amplitudes.This process amplifies the seismic signal and noise,thereby substantially reducing the signal-tonoise ratio of seismic data.Therefore,this paper proposes a multichannel inversion absorption compensation method based on structure tensor regularization.First,the structure tensor is utilized to extract the spatial inclination of seismic signals,and the spatial prediction filter is designed along the inclination direction.The spatial prediction filter is then introduced into the regularization condition of multichannel inversion absorption compensation,and the absorption compensation is realized under the framework of multichannel inversion theory.The spatial predictability of seismic signals is also introduced into the objective function of absorption compensation inversion.Thus,the inversion system can effectively suppress the noise amplification effect during absorption compensation and improve the recovery accuracy of high-frequency signals.Synthetic and field data tests are conducted to demonstrate the accuracy and effectiveness of the proposed method.展开更多
A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machine...A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machinery.After the end face of the guide sleeve wears out,it still tightly adheres to the sealing valve seat under the pressure difference,achieving automatic wear compensation.Based on fluid-solid coupling technology,the structural strength of the rotary sealing device was checked.The influence of factors on the sealing performance of rotary sealing devices was studied using the control variable method.The results show that as the pressure of water increases,the leakage rate of the sealing device decreases,and after 30 MPa,the leakage rate is almost 0 mL/h.The temperature of the rotating sealing device increases with the increase of rotation speed or pressure,and the temperature is more affected by the rotation speed factor.The frictional torque increases with increasing pressure and is independent of rotational speed.Comprehensive analysis shows that the wear resistance and reliability level of the sealing guide sleeve material is PVDF>PEEK>PE>PA.This study designs a high-pressure automatic compensation wear rotary sealing device and selects the optimal sealing material,providing technical support for the application of high-pressure water jet in mining machinery.展开更多
基金supported by the National Natural Science Foundation of China(No.11905102)Hunan Provincial Postgraduate Research and Innovation Project(No.QL20230234)。
文摘In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused byαparticle ionizing radiation was proposed,and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions.The experimental results show thatαparticle response signal has highest accuracy at 9 dB gain,with an obvious“target-ring”distribution.With increasing cumulative dose,the CMOS APS pedestal tends to saturation while dead pixels continue increasing.Though some pixel damage recovers through natural annealing,the dead-to-noise ratio increases with irradiation time,reaching 32.54%after 72 h.A hierarchical clustering dead-pixel detection method is proposed,categorizing pixels into two types:those within and outside the response event.A classification compensation strategy combining mean and majority filtering is proposed.This compensation algorithm can address dead-pixel interference without affectingαparticle radiation response data.When iterated multiple times and with integration time exceeding 6.31 ms,the number of dead pixels can be effectively reduced.
基金supported by the National Key Research and Develop-ment Program of China(No.2020YFA0608100)the National Nat-ural Science Foundation of China(Nos.32071842 and 32101588).
文摘Urbanization alters vegetation productivity by both direct(ωd)and indirect(ω_(i))effects.The direct effect is from the change of vegetated area indicated by impervious surface intensity(ISI),while indirect effects arise from changes in urban environmental factors,such as near-surface air temperatures,precipitation,urban heat island(UHI)intensity,and population density(POP).The respective contributions ofω_(d) andω_(i) to vegetation net primary productivity(NPP)under various phases of urbanization are not well quantified.Using multisource remote-sensing data from 1990 to 2020,we analyzed the spatiotemporal variation in urban expansion and the effect thatω_(d) andω_(i) had on NPP in the megalopolis of Beijing,China,over 5-year intervals.During this period,Beijing underwent significant planar expansion rates of about 58.9 km^(2)/yr.Annual mean loss of NPP byω_(d) was estimated to be about 77.1 g C/(m^(2)·yr)during the 1990-2020 period,while annual mean improvement to NPP byω_(i) amounted to an increase of 28.9 g C/(m^(2)·yr).The NPP losses were partially offset by NPP improvements in the order of 18.6%-69.3%.The impact of forcing variables on NPP varied spatially.Air temperature,precipitation,UHI,POP,and ISI explained about 13.8%,23.2%,23.7%,14.7%,and 24.6%of the spatial variation in NPP.The impact of air temperature on NPP was related to available moisture,negatively affecting NPP in regions with water deficits.Our findings demonstrate the dual impact of urbanization on vegetation and underscore the necessity for spatially adaptive ecological management strategies in regions experiencing rapid urban growth.
基金supported by the the National Key R&D Program of China (Grant Nos.2023YFA1606900 and 2022YFA1602301)the National Natural Science Foundation of China (Grant Nos.12235003,12435010,and 12147101)+3 种基金the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2020B0301030008)the STCSM (Grant No.23590780100)the Natural Science Foundation of Shanghai (Grant No.23JC1400200)the China Postdoctoral Science Foundation (Grant No.2024M760483)。
文摘Measuring cross sections of nuclear reactions,such as the so-called“Holy Grail”reaction,^(12)C(σ,γ)^(16)O,is essential for understanding stellar nucleosynthesis but presents significant challenges due to extremely low cross sections.Key challenges include significant energy loss as ions penetrate the target material,limiting measurements to thin target layers.To overcome these obstacles,we propose a novel method,the in-target energy loss compensating(eLOC)method,specifically designed for gas targets,which utilizes a gas-filled magnetic field and accelerating electric fields to compensate for ion energy loss in the target.Simulations show that this approach significantly enhances the effective target thickness by over 140 times in the case of the“Holy Grail”reaction with an inverse-kinematics setup.This eLOC method may provide a powerful new tool for obtaining critical data in nuclear astrophysics,thereby advancing our understanding of stellar nucleosynthesis and the origins of elements in the universe,as well as benefiting other related fields such as isotope production.
基金supported by the National Natural Science Foundation of China[Grant No.71773091]the Graduate Student Science and Technology Innovation Program of College of Economics and Management[Grant No.JGYJSCXXM202308].
文摘The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestration in grasslands remains unclear.Based on panel data from prefecture-level cities in the Yellow River Basin(YRB)from 2000 to 2020,this study explored the effects of the GECP on grassland carbon sequestration in the YRB and its heterogeneity using a time-varying difference-in-differences(TV-DID)model.Subsequently,we predicted changes in carbon sequestration in grasslands under the influence of the GECP from 2021 to 2040 using a simulation.The main conclusions are as follows:First,the implementation of the GECP promoted carbon sequestration in grasslands.This conclusion was validated after conducting a series of robustness tests.Moreover,the effects of the GECP were heterogeneous across different geographical locations,highway densities,and grassland areas.Finally,the simulation results indicated that over the next 20 years,grassland carbon sequestration will generally increase but exhibit cyclical changes.The government should align the principles and objectives of the GECP with local geographic conditions,resource availability,and socio-economic development.It must formulate and implement tailored policies that maximize the ecological protection benefits of the GECP and promote carbon sequestration in the grasslands of the YRB.
基金funded by the Gansu Soft Science Planning Project(Grant No.25JRZA170).
文摘This study aims to explore how the Wei River Basin can enhance the efficiency of horizontal ecological compensation to promote high-quality and sustainable development in the Yellow River Basin.To achieve this,a four-stage DEA(Data Envelopment Analysis)method was employed to evaluate the efficiency of ecological compensation in six prefecture-level cities within the Wei River Basin from 2001 to 2022.In addition,the K-prototype clustering analysis method was integrated to assess the regional differences in ECE(ecological compensation efficiency).The findings indicate:(1)the ecological compensation efficiency in the upstream areas of the Wei River Basin is significantly higher than in the downstream regions;(2)the influence of factors such as the proportion of the tertiary industry,population density and residents’disposable income on the efficiency of ecological compensation is significant;(3)after excluding environmental factors,the overall ecological compensation efficiency showed a significant improvement.Based on these insights,it is recommended that the provinces of Shaanxi and Gansu further establish a robust compensation fund operation mechanism,build a cross-regional ecological compensation upstream-downstream coordination system,and strengthen inter-basin economic cooperation mechanisms to promote dual-driven development through technological advancement and scale benefits,thereby advancing ecological protection and sustainable development in the Wei River Basin.
基金supported by the National Natural Science Foundation of China(Grant No.52130503)the Science and Technology Innovation Program of Hunan Province(Grants Nos.2023RC1046 and 2023GK2008)+2 种基金the Hunan Provincial Science and Technology Department(Grant No.2021JC0005)the Postgraduate Scientific Research Innovation Project of Hunan Province(Grant No.QL20220088)the Shenzhen Undertakes Major National Science and Technology Projects(Grant No.CJGJZD20220517142406015).
文摘In an ultraprecision turning process for small-diameter optical aspheric workpieces,tool-profile errors induce mid-frequency errors in the workpiece profile,limiting further improvements in precision.In this study,an XZB three-axis linkage ultraprecision machining method is proposed,and the effects of tool-center errors are analyzed.To address residual errors in Z-direction profile-error compensation,a workpiece normal-profile-error compensation method is proposed.After XZB three-axis linkage turning and compensation,the workpiece profile error(PV)reaches 0.086μm,surpassing the precision of XZ two-axis machining,and mid-frequency errors are reduced.Compared with Z-direction profile-error compensation,which results in a profile error of 0.092μm,normal-profile-error compensation reduces PV to 0.047μm,considerably improving aspheric accuracy.Experimental results demonstrate that XZB three-axis linkage machining significantly improves the aspheric workpiece profile,enhancing both its accuracy and surface quality.This method reduces mid-frequency errors,and the subsequent application of normal-profile-error compensation further refines the profile,achieving higher overall accuracy.
文摘Thermal errors in CNC machine tools,particularly those involving the spindle,significantly affect machining accuracy and performance.These errors,caused by temperature fluctuations in the spindle and surrounding components,result in dimensional deviations that can lead to poor part quality and reduced precision in high-speed manufacturing processes.This paper explores thermal error modeling and compensation methods for the spindle of five-axis CNC machine tools.A detailed analysis of the heat generation,transfer mechanisms,and finite element analysis(FEA)is presented to develop accurate thermal error models.Compensation techniques,such as model-based methods,sensor-based methods,real-time compensation algorithms,and hybrid approaches,are critically reviewed.This study also discusses the challenges in real-time compensation and the integration of thermal error compensation with machine tool control systems.The objective is to provide a comprehensive understanding of thermal error phenomena and their compensation strategies,ultimately contributing to the enhancement of machining accuracy in advanced manufacturing applications.
基金supported by the Youth Project of National Natural Science Foundation of China(No.61505145)the Tianjin Science and Technology Commissioner Project(No.20YDTPJC02010)+1 种基金the Tianjin Municipal Education Commission(No.2021KJ003)the Tianjin Zhonghuan Tianjia Electronics Company(No.HX20193)。
文摘Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed solution in the dual-wavelength spectral method based on the Lambert-Beer law additive principle.It compensates for the influence of turbidity on the absorption coefficient of the COD solution at 355 nm by the absorption spectrum coefficient of the mixed solution at 623 nm.This paper establishes a linear relationship model between the absorbance difference of the mixed solution at 355 nm and 623 nm and COD.The experimental determination coefficient R2 of the model is 0.98335,with a relative error of 3.5%and an average error of 0.7 mg/L.The design of the model is simple and easy to systematize,which is of strong significance for practical application.
文摘The Hydro-Viscous Drive(HVD)speed regulating system finds extensive application in air transport transmission systems to regulate the stepless speed or conduct overload protection.However,its intrinsic hysteretic behaviors,such as the asymmetric hysteretic and dead zone,could introduce inaccuracy and delay in control applications,posing challenges to system regulation.This paper investigates a Nonlinear Hysteresis Compensation Control(NHCC)that consists of two parts to control the HVD output speed by operating the valve under different engine operating conditions.In the first part,the Inverse Hysteresis Compensator(IHC)based on major loop data is introduced for the asymmetric hysteresis characterization and compensation of the HVD speed control system of the power generation and distribution,which aims to reduce the hysteresis and dead zone effect and expand the effective input range.In the second part,the Active Disturbance Rejection Controller(ADRC)is employed to mitigate the hysteresis effects of the compensated system and remove the steady-state error,which allows real-time compensation of the estimated perturbations as state feedback to achieve the required performance.An experimental laboratory station has been fabricated to evaluate the proposed method.The test results show that the NHCC method can regulate the fan speed to the desired value(45 r/min at steady state)and broaden the effective input range to the full range under different engine conditions.Besides,the proposed control method can reduce the non-linearity of the input and output curves(from 18%to 4%)and compensate for the asymmetric hysteresis(from 38%to 5%).
基金supported by the National Natural Science Foundation of China(Nos.62063009,52262050)the National Key Research and Development Program during the 14th 5-Year Plan(No.2023YFB4302100)the Major Science and Technology Research and Development Special Project in Jiangxi Province(No.20232ACE01011).
文摘To address the issue of disturbance compensation deviation in linear active disturbance rejection control(LADRC),a linear active disturbance rejection control method with reference to the integral chain model(LADRC-R)is proposed.By constructing an ideal control reference model,a dynamic correlation between output deviation and uncompensated disturbances is established,and a dual-loop compensation mechanism is designed.Based on theoretical analysis and frequency-domain characteristics of typical first/second-order systems,this method maintains the parameter-tuning advantages of LADRC while reducing disturbance effects by 50%and introducing no phase lag during low-frequency disturbance suppression.Simulations on second-order systems verify its robustness under parameter perturbations,gain mismatch,and complex disturbances,and an optimized design scheme for the deviation compensator is proposed to suppress discontinuous measurement noise interference.Finally,the engineering effectiveness of this method in precision motion control is validated on an electromagnetic suspension platform,providing a new approach to improving the control performance of LADRC in environments with uncertain disturbances.
基金supported by National Natural Science Foundation of China(No.22278308 and 22109114)Open Foundation of Shanghai Jiao Tong University Shaoxing Research Institute of Renewable Energy and Molecular Engineering(Grant number:JDSX2022023).
文摘Hard carbon(HC)is widely used in sodium-ion batteries(SIBs),but its performance has always been limited by lowinitial Coulombic efficiency(ICE)and cycling stability.Cathode compensation agent is a favorable strategy to make up for the loss of active sodium ions consumed byHCanode.Yet it lacks agent that effectively decomposes to increase the active sodium ions as well as regulate carbon defects for decreasing the irreversible sodium ions consumption.Here,we propose 1,2-dihydroxybenzene Na salt(NaDB)as a cathode compensation agent with high specific capacity(347.9 mAh g^(-1)),lower desodiation potential(2.4–2.8 V)and high utilization(99%).Meanwhile,its byproduct could functionalize HC with more C=O groups and promote its reversible capacity.Consequently,the presodiation hard carbon(pHC)anode exhibits highly reversible capacity of 204.7 mAh g^(-1) with 98%retention at 5 C rate over 1000 cycles.Moreover,with 5 wt%NaDB initially coated on the Na3V2(PO4)3(NVP)cathode,the capacity retention of NVP + NaDB|HC cell could increase from 22%to 89%after 1000 cycles at 1 C rate.This work provides a new avenue to improve reversible capacity and cycling performance of SIBs through designing functional cathode compensation agent.
基金supported in part by the National Natural Science Foundation of China(No.51677030).
文摘The complex working environment of distribution networks tends to cause impermanent single-phase-to-ground(SPG)fault,and high-temperature ground fault arc is prone to endanger lives and power equipment,resulting in large-scale power outages and fire accidents.Thus,fault arc should be extinguished in time.Meanwhile,stable operation conditions of distribution networks and reliable load power supply should be guaranteed to provide high-quality customer service.This paper proposes an active mitigation strategy for SPG fault,and provide active and reactive power compensation at the same time by utilizing an improved flexible power electronic equipment(FPEE)with dc-link sources.These controls are decoupled from each other,so utilization of FPEE is maximized as much as possible.When a SPG fault occurs in distribution networks,FPEE can output,simultaneously,active power,reactive power,and SPG fault compensation current by controlling output current on the d,q,0 coordinate system,respectively.During normal operation of distribution networks,the FPEE can be used as a virtual synchronous generator to compensate load power and its fluctuation.The proposed simultaneous multi-function can also be applied in other cases.Simulation cases are implemented to verify principles and practicability.
基金supported by the National Natural Science Foundation of China(Grant number 42201302)the"Double First-Class"University Construction Project of Lanzhou University(Grant number:561120213)。
文摘The horizontal ecological compensation plays an important role in balancing the interests of all parties and coordinating regional development in the basin.However,the mechanism of ecological compensation based on embodied carbon emissions is still poorly understood.Here,taking the Yellow River Basin as the research area,we use the multi-regional input-output(MRIO)model to measure the embodied carbon transfers between its seven urban agglomerations in 2012 and 2017 from the viewpoint of value-added trade benefits.Further,for the first time,the green trade benefits and ecological compensation amounts are analyzed.The results indicate that:(1)The transfer of trade-embodied carbon among the urban agglomerations in the basin showed obvious spatial heterogeneity and geographic proximity effects,and trade-embodied carbon outflows(inflows)had a pattern of"highest in the midstream,second in the downstream,and lowest in the upstream".(2)The industry composition of the urban agglomerations in relation to embodied carbon outflows(inflows)was similar,mainly in the service and heavy manufacturing industries.(3)The spatial pattern of green trade benefits in the basin had shifted from"high in the north and low in the surrounding area"to"high in the east-central part and low in the west".(4)The pattern of ecological compensation in the basin had shifted from the upstream surplus,the middle and downstream deficit to the midstream deficit,and the upstream and downstream surplus.Therefore,we recommend improving energy structures in high-demand urban agglomerations by adopting clean energy,focusing on decarbonization and energy efficiency in resource-rich regions.Additionally,promoting low-carbon economies,especially in the service and heavy manufacturing industries,implementing differentiated emission reduction strategies,and optimizing carbon compensation mechanisms considering regional disparities and resource endowments are crucial.It is expected that the study can enrich the scientific basis of horizontal ecological compensation and increase the fairness of regional carbon emission rights allocation.
基金financially supported by the National Key Re-search and Development Program of China(No.2022YFC3700801)the Key R&D Program of Shandong Province,China(No.2024SFGC0102),the Jinan Bureau of Education(No.JNSX2023015)the Jinan Bureau of Science and Technology(No.202333042).
文摘Tetravalent tin(Sn^(4+))-based inorganic perovskite semiconductors like Cs_(2)SnI_(6)are expected to replace lead-based perovskite counterparts due to advantages such as structural stability and environmental friendliness.In this paper,we reported the dopant compensation effect in the component-dependent self-doped(111)-oriented Cs_(2)SnI_(6)thin films grown with pulsed laser deposition(PLD)at room temperature.The films were grown on(100)-SrTiO_(3)(STO)substrates at room temperature by PLD.Hall results of the Cs_(2)SnI_(6)films with different components realizing by controlling the ratio of SnI_(4)/CsI in the targets demonstrate a clear change of conductivity type from N-type to P-type,while the carrier concentration decreases from 1018 to 1013 and accordingly the film resistivity increases significantly from 3.8 to 2506Ωcm.The defect-relatedopticalfingerprints of Cs_(2)SnI_(6)films werealsoinvestigated withtemperature-dependent photoluminescence spectroscopy.At low temperatures of 10 K,the Cs_(2)SnI_(6)films exhibit donor-bound(D^(0)X)and donor-acceptor pair(DAP)emission,respectively,due to the self-doping effect.These re-sults indicate that controlling the composition of the PLD target is a powerful way to tune the electrical properties of Cs_(2)SnI_(6)films for possible applications in solar cells or X-ray detectors.
基金this study was supported by National Forestry Sci-ence and Technology Support Program (No.2006BAD03A15)Key laboratory of Forest Silvculture of the State Forestry Ministration’ Sus-tentation Fund
文摘On the basis of analysis of the present situation of the ecological benefit compensation in China and foreign countries, this paper discusses the necessity, principle and approach of establishing the compensation mechanism of forest ecological benefit, as well as compensation standard in order to provide scientific basis for further perfecting the compensation mechanism of forest ecological engineering benefit in China. It is suggested that setting up the compensation mechanism of forest ecological benefit can not only provide the steady funds source of managing and protecting forest resources, but resolve radically the dynamic and mechanism problems of commonweal forest ecological engineering construction, which will produce a widespread and profound influence on China forestry and ecological construction.
基金Earth Observation and Navigation Special,Research on Low Temperature Superconducting Aeromagnetic Vector Gradient Observation Technology(2021YFB3900201)projectState Key Laboratory of Remote Sensing Science project.
文摘In this paper,we investigate the method of compensating LTS SQUID Gradiometer Systems data.By matching the attitude changes of the pod in fl ight to the anomalies of the magnetic measurement data,we find that the yaw attitude changes most dramatically and corresponds best to the magnetic data anomaly interval.Based on this finding,we solved the compensation model using least squares fitting and Huber's parametric fitting.By comparison,we found that the Huber parametric fit not only eliminates the interference introduced by attitude changes but also retains richer anomaly source information and therefore obtains a higher signal-to-noise ratio.The experimental results show that the quality of the magnetometry data obtained by using the compensation method proposed in this paper has been significantly improved,and the mean value of its improvement ratio can reach 118.93.
文摘Industrial robots are integral to modern manufacturing systems,enabling high precision,high throughput,and flexibility.However,errors in accuracy and repeatability,which arise from a variety of sources such as mechanical wear,calibration issues,and environmental factors,can significantly impact the performance of industrial robots.This paper aims to explore the theoretical modeling of errors in industrial robot systems and propose compensation strategies to enhance their accuracy and repeatability.Key factors contributing to errors,such as kinematic,dynamic,and environmental influences,are discussed in detail.Additionally,the paper explores various compensation techniques,including geometric error compensation,dynamic compensation,and adaptive control approaches.Through the integration of error modeling and compensation methods,industrial robots can achieve improved performance,ensuring higher operational efficiency and product quality.The paper concludes by highlighting the challenges and future research directions for improving the accuracy and repeatability of industrial robots in practical applications.
基金Supported by Shanxi Provincial Natural Science Foundation(Grant No.2021JM010)The Youth Innovation Team of Shaanxi Universities.
文摘This study aimed to identify and compensate for the geometric errors of the double swiveling axes in a five-axis computer numerical control(CNC)machining center.Hence,a three-dimensional coordinate calculation algorithm for a measured point with additional rotational rigid body motion constraints is proposed.The motion constraints of the rotational rigid body were analyzed,and a mathematical model of the measured point algorithm in the swiveling axes was established.The Levenberg-Marquard method was used to solve the nonlinear superstatically determined equations.The spatial coordinate error was used to separate the spatial deviation of the measured point.An identification model of the position-independent and position-dependent geometric errors was established.The three-dimensional coordinate-solving algorithm of the measured point in the swiveling axis and geometric error identification method based on the Monte Carlo method were analyzed numerically.Geometric error measurement and cutting experiments were performed on a VMC25100U five-axis machining center,which integrated two swiveling axes.Geometric errors of the A-and B-axes were identified and measured experimentally.The angular positioning errors before and after compensation were measured using a laser interferometer,which verified the effectiveness of the proposed algorithm.A cutting experiment of a round table part was performed.The shape and position accuracy of the processed part before and after compensation were detected using a coordinate measuring machine.It verified that the geometric error of the swiveling axis was effectively compensated by the algorithm proposed herein.
基金funded by the National Key R&D Program of China(Grant no.2018YFA0702504)the Sinopec research project(P22162).
文摘Absorption compensation is a process involving the exponential amplification of reflection amplitudes.This process amplifies the seismic signal and noise,thereby substantially reducing the signal-tonoise ratio of seismic data.Therefore,this paper proposes a multichannel inversion absorption compensation method based on structure tensor regularization.First,the structure tensor is utilized to extract the spatial inclination of seismic signals,and the spatial prediction filter is designed along the inclination direction.The spatial prediction filter is then introduced into the regularization condition of multichannel inversion absorption compensation,and the absorption compensation is realized under the framework of multichannel inversion theory.The spatial predictability of seismic signals is also introduced into the objective function of absorption compensation inversion.Thus,the inversion system can effectively suppress the noise amplification effect during absorption compensation and improve the recovery accuracy of high-frequency signals.Synthetic and field data tests are conducted to demonstrate the accuracy and effectiveness of the proposed method.
基金Supported by Jiangsu Provincial Natural Science Foundation(Grant No.BK20231497)Jiangsu Provincial Post graduate Research&Practice Innovation Program(Grant No.KYCX25_2982)+3 种基金China University of Mining and Technology Graduate Innovation Program(Grant No.2025WLKXJ094)National Natural Science Foundation of China(Grant No.51975573)National Key R&D Program of China(Grant No.2022YFC2905600)Priority Academic Program Development of Jiangsu Higher Education Institute of China.
文摘A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machinery.After the end face of the guide sleeve wears out,it still tightly adheres to the sealing valve seat under the pressure difference,achieving automatic wear compensation.Based on fluid-solid coupling technology,the structural strength of the rotary sealing device was checked.The influence of factors on the sealing performance of rotary sealing devices was studied using the control variable method.The results show that as the pressure of water increases,the leakage rate of the sealing device decreases,and after 30 MPa,the leakage rate is almost 0 mL/h.The temperature of the rotating sealing device increases with the increase of rotation speed or pressure,and the temperature is more affected by the rotation speed factor.The frictional torque increases with increasing pressure and is independent of rotational speed.Comprehensive analysis shows that the wear resistance and reliability level of the sealing guide sleeve material is PVDF>PEEK>PE>PA.This study designs a high-pressure automatic compensation wear rotary sealing device and selects the optimal sealing material,providing technical support for the application of high-pressure water jet in mining machinery.
