The Regional Comprehensive Economic Partnership(RCEP)has created favorable conditions for building deeply integrated agricultural value chains(AVC)in Asia-Pacific.Based on the RCEP agreement,this study employed the gl...The Regional Comprehensive Economic Partnership(RCEP)has created favorable conditions for building deeply integrated agricultural value chains(AVC)in Asia-Pacific.Based on the RCEP agreement,this study employed the global trade analysis project(GTAP)model to evaluate the impact of RCEP on AVC of member countries in terms of time,tariff reduction,and reduction of non-tariff barriers(NTB).The results indicate that(1)the implementation of RCEP boosts the value-added to agricultural exports for most member countries,particularly in competitive industries;(2)the increase in domestic production and processing capacity,reflected in domestic value-added(DVA),is the primary factor driving the rise in the value-added of agricultural exports across various industries of member countries;(3)RCEP enhances the participation of most regional countries in AVC,with varying impacts on AVC positioning,thereby fostering regional AvC development;and(4)RCEP has a positive effect on AVC indicators both in the short and long term,with the effect becoming more pronounced over time.Additionally,reducing NTB enhances the positive effects of tariff reductions on AVC indicators.Based on the analyses,the following recommendations are proposed:(1)Leverage the development opportunities arising from RCEP implementation to enhance the agricultural DVA;(2)capitalize on cooperative opportunities created by RCEP to build cohesive regional AVC;and(3)prioritize the effective implementation of RCEP'shigh-qualityrules.展开更多
Yellow rust(Puccinia striiformis f.sp.Tritici,YR)and fusarium head blight(Fusarium graminearum,FHB)are the two main diseases affecting wheat in the main grain-producing areas of East China,which is common for the two ...Yellow rust(Puccinia striiformis f.sp.Tritici,YR)and fusarium head blight(Fusarium graminearum,FHB)are the two main diseases affecting wheat in the main grain-producing areas of East China,which is common for the two diseases to appear simultaneously in some main production areas.It is necessary to discriminate wheat YR and FHB at the regional scale to accurately locate the disease in space,conduct detailed disease severity monitoring,and scientific control.Four images on different dates were acquired from Sentinel-2,Landsat-8,and Gaofen-1 during the critical period of winter wheat,and 22 remote sensing features that characterize the wheat growth status were then calculated.Meanwhile,6 meteorological parameters that reflect the wheat phenological information were also obtained by combining the site meteorological data and spatial interpolation technology.Then,the principal components(PCs)of comprehensive remote sensing and meteorological features were extracted with principal component analysis(PCA).The PCs-based discrimination models were established to map YR and FHB damage using the random forest(RF)and backpropagation neural network(BPNN).The models’performance was verified based on the disease field truth data(57 plots during the filling period)and 5-fold cross-validation.The results revealed that the PCs obtained after PCA dimensionality reduction outperformed the initial features(IFs)from remote sensing and meteorology in discriminating between the two diseases.Compared to the IFs,the average area under the curve for both micro-average and macro-average ROC curves increased by 0.07 in the PCs-based RF models and increased by 0.16 and 0.13,respectively,in the PCs-based BPNN models.Notably,the PCs-based BPNN discrimination model emerged as the most effective,achieving an overall accuracy of 83.9%.Our proposed discrimination model for wheat YR and FHB,coupled with multi-source remote sensing images and meteorological data,overcomes the limitations of a single-sensor and single-phase remote sensing information in multiple stress discrimination in cloudy and rainy areas.It performs well in revealing the damage spatial distribution of the two diseases at a regional scale,providing a basis for detailed disease severity monitoring,and scientific prevention and control.展开更多
In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads th...In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide.This is equivalent to including an additional inductance-capacitance for energy storage,which realizes the slow-wave effect.A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth.In the frequency band between 8-12 GHz,the measured results show that the delay multiplier of the delay line reaches 4 times,i.e.,delay line’s delay time is 4 times larger than 50Ωmicrostrip line with same length.Furthermore,the delay fluctuation,i.e.,the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%,the insertion loss is less than-2.5 dB,and the return loss is less than-15 dB.Compared with the existing delay lines,the proposed delay line has the advantages of high delay efficiency,low delay error,wide bandwidth and low loss,which has good practical value and application prospects.展开更多
Multispectral imaging plays a crucial role in simultaneously capturing detailed spatial and spectral information,which is fundamental for understanding complex phenomena across various domains.Traditional systems face...Multispectral imaging plays a crucial role in simultaneously capturing detailed spatial and spectral information,which is fundamental for understanding complex phenomena across various domains.Traditional systems face significant challenges,such as large volume,static function,and limited wavelength selectivity.Here,we propose an innovative dynamic reflective multispectral imaging system via a thermally responsive cholesteric liquid crystal based planar lens.By employing advanced photoalignment technology,the phase distribution of a lens is imprinted to the liquid crystal director.The reflection band is reversibly tuned from 450 nm to 750 nm by thermally controlling the helical pitch of the cholesteric liquid crystal,allowing selectively capturing images in different colors.This capability increases imaging versatility,showing great potential in precision agriculture for assessing crop health,noninvasive diagnostics in healthcare,and advanced remote sensing for environmental monitoring.展开更多
Global Navigation Satellite Systems(GNSSs)face significant security threats from spoofing attacks.Typical anti-spoofing methods rely on estimating the delays between spoofing and authentic signals using multicorrelato...Global Navigation Satellite Systems(GNSSs)face significant security threats from spoofing attacks.Typical anti-spoofing methods rely on estimating the delays between spoofing and authentic signals using multicorrelator outputs.However,the accuracy of the delay estimation is limited by the spacing of the correlators.To address this,an innovative anti-spoofing method is introduced,which incorporates distinct coarse and refined stages for more accurate spoofing estimation.By leveraging the coarse delay estimates obtained through maximum likelihood estimation,the proposed method establishes the Windowed Sum of the Relative Delay(WSRD)statistics to detect the presence of spoofing signals.The iterative strategy is then employed to enhance the precision of the delay estimation.To further adapt to variations in the observation noise caused by spoofing intrusions and restore precise position,velocity,and timing solutions,an adaptive extended Kalman filter is proposed.This comprehensive framework offers detection,mitigation,and recovery against spoofing attacks.Experimental validation using datasets from the Texas Spoofing Test Battery(TEXBAT)demonstrates the effectiveness of the proposed anti-spoofing method.With 41 correlators,the method achieves a detection rate exceeding 90%at a false alarm rate of 10-5,with position or time errors below 15 m.Notably,this refined anti-spoofing approach shows robust detection and mitigation capabilities,requiring only a single antenna without the need for additional external sensors.These advancements can significantly contribute to the development of GNSS anti-spoofing measures.展开更多
Deep ultraviolet coherent light,particularly at the wavelength of 193 nm,has become indispensable for semiconductor lithography.We present a compact solid-state nanosecond pulsed laser system capable of generating 193...Deep ultraviolet coherent light,particularly at the wavelength of 193 nm,has become indispensable for semiconductor lithography.We present a compact solid-state nanosecond pulsed laser system capable of generating 193-nm coherent light at the repetition rate of 6 kHz.One part of the 1030-nm laser from the homemade Yb:YAG crystal amplifier is divided to generate 258 nm laser(1.2 W)by fourth-harmonic generation,and the rest is used to pump an optical parametric amplifier producing 1553 nm laser(700 mW).Frequency mixing of these beams in cascaded LiB_(3)O_(5) crystals yields a 193-nm laser with 70-mW average power and a linewidth of less than 880 MHz.By introducing a spiral phase plate to the 1553-nm beam before frequency mixing,we generate a vortex beam carrying orbital angular momentum.This is,to our knowledge,the first demonstration of a 193-nm vortex beam generated from a solid-state laser.Such a beam could be valuable for seeding hybrid ArF excimer lasers and has potential applications in wafer processing and defect inspection.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
Bi_(2)YbO_(4)Cl with a fluorite layer structure belongs to the family of the bismuth rare-earth oxyhalides Bi_(2)REO_(4)X(X=Cl,B r,I).However,the synthesis and photoelectric properties of Bi_(2)YbO_(4)Cl have almost n...Bi_(2)YbO_(4)Cl with a fluorite layer structure belongs to the family of the bismuth rare-earth oxyhalides Bi_(2)REO_(4)X(X=Cl,B r,I).However,the synthesis and photoelectric properties of Bi_(2)YbO_(4)Cl have almost not been reported.In this work,Bi_(2)YbO_(4)Cl was synthesized using the solid-state method and the solvothermal method.Yb3+ions show a strong characteristic absorption peak at 980 nm,which was measured by ultraviolet-visible-near-infrared absorption spectra.The transient photoconductivity of Bi_(2)YbO_(4)Cl was obtained by time-resolved terahertz spectroscopy system under 400 and 800 nm laser excitations,respectively.The frequency-dependent transient photoconductivity analysis reveals the Drude-Smith behavior in Bi_(2)YbO_(4)Cl.Under photoexcitation,the hot charge carriers with a long relaxation lifetime and a carrier mobility of 48 cm^(2)/(V·s) are obtained.The synthesis of Bi_(2)YbO_(4)Cl is of great significance for the development of novel photocatalytic and photo harvesting materials with broad spectral response.展开更多
Internal solitary waves(ISWs)have considerable energy to drive the mixing of water masses in the Sulu Sea.The propagation speed is one of the critical parameters in quantifying the energy budget of the ISWs.We collect...Internal solitary waves(ISWs)have considerable energy to drive the mixing of water masses in the Sulu Sea.The propagation speed is one of the critical parameters in quantifying the energy budget of the ISWs.We collected 1354 groups of ISWs’speeds from tandem satellite remote sensing images with temporal intervals shorter than 25 min and analyzed their spatial and multi-scale temporal variations in the Sulu Sea.We found that water depth plays an important role in modulating the spatial variation of wave speeds,which increase exponentially with water depth with a power of 0.26.Tidal currents,ocean stratification,background circulation,and climate affect the temporal variations of wave speeds from days to months or years.The fortnightly spring/neap tidal currents cause daily variations of wave speeds up to 40%by modulating the ISW amplitudes.In addition to the well-accepted results that monthly variations of wave speeds are related to density stratification,we found that enhanced stratification increases wave speeds,and the background circulation leads to a maximum decrease of 0.27 m/s in the linear counterparts of wave speed.Moreover,the averaged wave speed collected in October is lower than the corresponding linear one possibly due to some unknown dynamical processes or underestimation of background current.As for the interannual variations,we show that wave speed increases in La Niña years and decreases in El Niño years as a result of the climatic modulation on the depth of the maximum value of buoyancy frequency.展开更多
The wheat above-ground biomass(AGB)is an important index that shows the life activity of vegetation,which is of great significance for wheat growth monitoring and yield prediction.Traditional biomass estimation method...The wheat above-ground biomass(AGB)is an important index that shows the life activity of vegetation,which is of great significance for wheat growth monitoring and yield prediction.Traditional biomass estimation methods specifically include sample surveys and harvesting statistics.Although these methods have high estimation accuracy,they are time-consuming,destructive,and difficult to implement to monitor the biomass at a large scale.The main objective of this study is to optimize the traditional remote sensing methods to estimate the wheat AGBbased on improved convolutional features(CFs).Low-cost unmanned aerial vehicles(UAV)were used as the main data acquisition equipment.This study acquired image data acquired by RGB camera(RGB)and multi-spectral(MS)image data of the wheat population canopy for two wheat varieties and five key growth stages.Then,field measurements were conducted to obtain the actual wheat biomass data for validation.Based on the remote sensing indices(RSIs),structural features(SFs),and CFs,this study proposed a new feature named AUR-50(multi-source combination based on convolutional feature optimization)to estimate the wheat AGB.The results show that AUR-50 could estimate the wheat AGB more accurately than RSIs and SFs,and the average R^(2) exceeded 0.77.In the overwintering period,AUR-50_(MS)(multi-source combination with convolutional feature optimization using multispectral imagery)had the highest estimation accuracy(R^(2) of 0.88).In addition,AUR-50 reduced the effect of the vegetation index saturation on the biomass estimation accuracy by adding CFs,where the highest R^(2) was 0.69 at the flowering stage.The results of this study provide an effective method to evaluate the AGB in wheat with high throughput and a research reference for the phenotypic parameters of other crops.展开更多
Intracortical neural interfaces directly connect brain neurons with external devices to achieve high temporal resolution and spatially precise sampling of neural activity.When applied to freely moving animals,this tec...Intracortical neural interfaces directly connect brain neurons with external devices to achieve high temporal resolution and spatially precise sampling of neural activity.When applied to freely moving animals,this technology provides in-depth insight into the underlying neural mechanisms for their movement and cognition in real-world scenarios.However,the application of implanted devices in freely moving animals is limited by restrictions on their behavioral freedom and physiologic impact.In this paper,four technological directions for ideal implantable neural interface devices are analyzed:higher spatial density,improved biocompatibility,enhanced multimodal detection of electrical/neurotransmitter signals,and more effective neural modulation.Finally,we discuss how these technological developments have been applied to freely moving animals to provide better insight into neuroscience and clinical medicine.展开更多
Passive surface wave imaging has been a powerful tool for near-surface characterization in urban areas,which extracts surface wave signals from ambient seismic noise and then estimates subsurface shear wave velocity b...Passive surface wave imaging has been a powerful tool for near-surface characterization in urban areas,which extracts surface wave signals from ambient seismic noise and then estimates subsurface shear wave velocity by inversion of the measured phase velocity.The high-frequency(approximately>1 Hz)seismic noise fields in urban environments are dominantly induced by human activities such as the vehicle traffic.Traffic seismic sources are nonrandomly distributed in time and space.Applying standard interferometric techniques to recordings from these nonrandom noise sources makes the Green’s function liable to estimation errors.We analyze the influence of using nonrandom traffic seismic sources for surface wave imaging.With nonrandom traffic seismic sources in time,spurious signals are generated in the cross-correlation function.With nonrandom traffic seismic sources in space,surface-wave phase velocities could be overestimated in the dispersion measurement.We provide an overview of solutions for surface-wave imaging with nonrandom traffic seismic sources in time and space,aiming to improve the retrieval of high-frequency surface waves and achieve reliable results from ultrashort(tens of seconds)observations for near-surface characterization.展开更多
Neuromodulation techniques effectively intervene in cognitive function,holding considerable scientific and practical value in fields such as aerospace,medicine,life sciences,and brain research.These techniques utilize...Neuromodulation techniques effectively intervene in cognitive function,holding considerable scientific and practical value in fields such as aerospace,medicine,life sciences,and brain research.These techniques utilize electrical stimulation to directly or indirectly target specific brain regions,modulating neural activity and influencing broader brain networks,thereby regulating cognitive function.Regulating cognitive function involves an understanding of aspects such as perception,learning and memory,attention,spatial cognition,and physical function.To enhance the application of cognitive regulation in the general population,this paper reviews recent publications from the Web of Science to assess the advancements and challenges of invasive and non-invasive stimulation methods in modulating cognitive functions.This review covers various neuromodulation techniques for cognitive intervention,including deep brain stimulation,vagus nerve stimulation,and invasive methods using microelectrode arrays.The non-invasive techniques discussed include transcranial magnetic stimulation,transcranial direct current stimulation,transcranial alternating current stimulation,transcutaneous electrical acupoint stimulation,and time interference stimulation for activating deep targets.Invasive stimulation methods,which are ideal for studying the pathogenesis of neurological diseases,tend to cause greater trauma and have been less researched in the context of cognitive function regulation.Non-invasive methods,particularly newer transcranial stimulation techniques,are gentler and more appropriate for regulating cognitive functions in the general population.These include transcutaneous acupoint electrical stimulation using acupoints and time interference methods for activating deep targets.This paper also discusses current technical challenges and potential future breakthroughs in neuromodulation technology.It is recommended that neuromodulation techniques be combined with neural detection methods to better assess their effects and improve the accuracy of non-invasive neuromodulation.Additionally,researching closed-loop feedback neuromodulation methods is identified as a promising direction for future development.展开更多
Oceanic dissolved oxygen(DO)concentration is crucial for assessing the status of marine ecosystems.Against the backdrop of global warming,DO shows a general decrease,posing a threat to the health of marine ecosystems....Oceanic dissolved oxygen(DO)concentration is crucial for assessing the status of marine ecosystems.Against the backdrop of global warming,DO shows a general decrease,posing a threat to the health of marine ecosystems.Therefore,there is an urgent need to develop advanced tools to characterize the spatio-temporal variations of three-dimensional(3D)DO.To address this challenge,this study introduces the Light Gradient Boosting Machine(Light-GBM),combining satellite remote sensing and reanalysis data with Biogeochemical Argo data to accurately reconstruct the 3D DO structure in the Mediterranean Sea from 2010 to 2022.Various environmental parameters are incorporated as inputs,including spatiotemporal features,meteorological characteristics,and ocean color properties.The LightGBM model demonstrates excellent performance on the testing dataset with R^(2) of 0.958.The modeled DO agrees better with in-situ measurements than products from numerical models.Using the Shapley Additive exPlanations method,the contributions of input features are assessed.Sea surface temperatures provide a correlation with DO at the sea surface,while spatial coordinates supplement the view of the ocean interior.Based on the reconstructed 3D DO structure,we identify an oxygen minimum zone in the western Mediterranean that expands continuously,reaching depths of approximately 300–800 m.The western Mediterranean exhibits a significant declining trend.This study enhances marine environmental evidence by proposing a precise and cost-effective approach for reconstructing 3D DO,thereby offering insights into the dynamics of DO variations under changing climatic conditions.展开更多
This work uses advanced remote sensing to precisely extract hydrological information,supporting transmission network planning.High-resolution water body mapping lets designers optimize routes to avoid ecologically sen...This work uses advanced remote sensing to precisely extract hydrological information,supporting transmission network planning.High-resolution water body mapping lets designers optimize routes to avoid ecologically sensitive areas,achieving environmental protection,cost efficiency,and enhanced operational safety.The methodology provides a scalable,replicable framework for intelligent obstacle avoidance in power grid development,applicable to other regions and sectors with similar planning needs.展开更多
Chlorophyll a(Chl a)is a key photosynthetic pigment and an essential indicator of phytoplankton biomass.Accurate Chl a measurements are crucial for understanding marine biogeochemical processes.China launched the Chin...Chlorophyll a(Chl a)is a key photosynthetic pigment and an essential indicator of phytoplankton biomass.Accurate Chl a measurements are crucial for understanding marine biogeochemical processes.China launched the Chinese Ocean Color and Temperature Scanner(COCTS)aboard the HY-1D satellite in 2020,yet its Chl a products require further validation in complex coastal waters.This study assesses HY-1D Chl a products in the Bohai and Yellow Seas,two optically complex coastal regions,using in situ data collected during multiple cruises.Additionally,we compare HY-1D Chl a products with those from the Moderate Resolution Imaging Spectroradiometer(MODIS)and the Visible Infrared Imaging Radiometer Suite(VIIRS).We observed that although Chl a products from HY-1D are generally consistent with those from the MODIS and VIIRS in spatial distribution,there are still significant errors when compared with in situ data.Therefore,we developed a new blended algorithm to improve the accuracy of HY-1D Chl a products.The algorithm distinguishes between turbid and relatively clean waters using a classification index based on the ratio of remote sensing reflectance(R_(rs)(λ)).After the initial classification,we developed targeted algorithms based on the optical properties of different water bodies.The new model shows a significant improvement,reducing the mean absolute percentage error(MAPE)from 43.1%to 24.3%.Additionally,merging Chl a data from HY-1D,MODIS,and VIIRS maintains good accuracy,with HY-1D Chl a products significantly enhancing data coverage and robustness.This research provides important support for producing high-quality HY-1D Chl a products for coastal waters.展开更多
Zinc is recognized as a vital biological element for animals and plants.Both zinc deficiency and excess will cause damage to cells,and zinc deficiency in the human body may lead to severe health problems.Zinc deficien...Zinc is recognized as a vital biological element for animals and plants.Both zinc deficiency and excess will cause damage to cells,and zinc deficiency in the human body may lead to severe health problems.Zinc deficiency has been identified as a global nutritional issue.Wheat,one of the most significant food crops for humans,is primarily planted in potentially zinc-deficient,calcareous soils in China.It proves to be a major global challenge to increase the zinc concentration in wheat crops to boost crop yields and improve human health.This study investigated the growth process of wheat in calcareous soils with various zinc concentrations using outdoor pot experiments and systematically explored the characteristics and mechanism of zinc transport in the soil-wheat system.The results indicate that the zinc concentrations in various wheat organs decreased in the order of roots,stems,and leaves in the jointing stage and in the order of seeds,roots,and stems in the mature stage.Overall,the zinc enrichment in various wheat organs decreased in the order of seeds,roots,stems,and leaves.In the case of zinc deficiency in soils,wheat roots exhibited elevated zinc availability in the rhizosphere by secreting phytosiderophores.This enhances the zinc uptake capacity of wheat roots.In the case of sufficient zinc supply from soils,chelated zinc formed with citric acid as the chelating ligand occurred stably in soils,contributing to enhanced utilization and uptake rates of zinc,along with elevated transport and enrichment capacities of zinc inside the plants.The results indicate that the zinc concentration in wheat seeds can be somewhat enhanced by regulating the background value of bioavailable zinc concentration in soils.A moderate zinc concentration gradient of 1.0 mg/kg is unfavorable for zinc accumulation in wheat seeds,while a high zinc concentration gradient of 6.0 mg/kg corresponds to the highest degree of zinc enrichment in wheat seeds.This study holds critical scientific significance for enhancing the zinc supply capacity of soils,increasing the zinc concentrations in wheat seeds,and,accordingly,addressing zinc deficiency in the human body.Additionally,this study offers a mechanistic reference and basis for research on the interplay between soils,plants,and human health.展开更多
In the context of urbanization,air pollution has emerged as a significant environmental challenge.A thorough understanding of their transport pathways,especially at a national scale,is essential for environmental prot...In the context of urbanization,air pollution has emerged as a significant environmental challenge.A thorough understanding of their transport pathways,especially at a national scale,is essential for environmental protection and policy-making.However,it remains partially elusive due to the constraints of available data and analytical methods.This study proposed a data-driven spatiotemporal correlation analysis method employing the Dynamic Time Warping(DTW).We represented the first comprehensive attempt to chart the long-term and nationwide transport pathways of PM_(2.5) utilizing an extensive dataset spanning from 2000 to 2021 across China,which is crucial for understanding long-term air pollution trends.Compared with traditional chemical transport models(CTMs),this data-driven method can generate transport pathways of PM_(2.5) without requiring extensive meteorological or emission data,and suggesting fundamentally consistent spatial distribution and trends.Our analysis reveals that China’s transport pathways are notably pronounced in the Northwest(34%of the total pathways in China),Southwest(22%),and North(21%)regions,with less significant pathways in the Northeast(10%)region and isolated occurrences elsewhere.Additionally,a notable decrease in the number of China’s PM_(2.5) transport pathways,similar to annual average concentrations,was observed after 2013,aligning with stricter environmental regulations.Furthermore,we have demonstrated the feasibility of applying our method to the transport pathways of other gaseous pollutants.The approach is effective in detecting and quantifying air pollutants’transport pathways,even in regions like the Northwest with limited monitoring infrastructure,which may aid in environmental decision-making.The study will notably improve the current understanding of air pollutants’transport process,providing a new perspective for studying the large-scale spatiotemporal correlations.展开更多
As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could ra...As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could range from kilometers to tens of kilometers, and even hundreds and thousands of kilometers. Therefore, it is crucial to develop effective long-range path planning for lunar rovers to meet the demands of lunar patrol exploration. This paper presents a hierarchical map model path planning method that utilizes the existing high-resolution images, digital elevation models and mineral abundance maps. The objective is to address the issue of the construction of lunar rover travel costs in the absence of large-scale, high-resolution digital elevation models. This method models the reference and semantic layers using the middle- and low-resolution remote sensing data. The multi-scale obstacles on the lunar surface are extracted by combining the deep learning algorithm on the high-resolution image, and the obstacle avoidance layer is modeled. A two-stage exploratory path planning decision is employed for long-distance driving path planning on a global–local scale. The proposed method analyzes the long-distance accessibility of various areas of scientific significance, such as Rima Bode. A high-precision digital elevation model is created using stereo images to validate the method. Based on the findings, it can be observed that the entire route spans a distance of 930.32 km. The route demonstrates an impressive ability to avoid meter-level impact craters and linear structures while maintaining an average slope of less than 8°. This paper explores scientific research by traversing at least seven basalt units, uncovering the secrets of lunar volcanic activities, and establishing ‘golden spike’ reference points for lunar stratigraphy. The final result of path planning can serve as a valuable reference for the design, mission demonstration, and subsequent project implementation of the new manned lunar rover.展开更多
基金supported by the Major Subject of the National Social Science Foundation of China(21&ZD093)the Basic Research Funds of Chinese Academy of Agricultural Sciences(16100520240017)+1 种基金the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(CAASCSAERD-202402,10-IAED-04-2024)the earmarked fund for China Agriculture Research System(CARS-08).
文摘The Regional Comprehensive Economic Partnership(RCEP)has created favorable conditions for building deeply integrated agricultural value chains(AVC)in Asia-Pacific.Based on the RCEP agreement,this study employed the global trade analysis project(GTAP)model to evaluate the impact of RCEP on AVC of member countries in terms of time,tariff reduction,and reduction of non-tariff barriers(NTB).The results indicate that(1)the implementation of RCEP boosts the value-added to agricultural exports for most member countries,particularly in competitive industries;(2)the increase in domestic production and processing capacity,reflected in domestic value-added(DVA),is the primary factor driving the rise in the value-added of agricultural exports across various industries of member countries;(3)RCEP enhances the participation of most regional countries in AVC,with varying impacts on AVC positioning,thereby fostering regional AvC development;and(4)RCEP has a positive effect on AVC indicators both in the short and long term,with the effect becoming more pronounced over time.Additionally,reducing NTB enhances the positive effects of tariff reductions on AVC indicators.Based on the analyses,the following recommendations are proposed:(1)Leverage the development opportunities arising from RCEP implementation to enhance the agricultural DVA;(2)capitalize on cooperative opportunities created by RCEP to build cohesive regional AVC;and(3)prioritize the effective implementation of RCEP'shigh-qualityrules.
基金supported by National Key R&D Program of China(2022YFD2000100)National Natural Science Foundation of China(42401400)Zhejiang Provincial Key Research and Development Program(2023C02018).
文摘Yellow rust(Puccinia striiformis f.sp.Tritici,YR)and fusarium head blight(Fusarium graminearum,FHB)are the two main diseases affecting wheat in the main grain-producing areas of East China,which is common for the two diseases to appear simultaneously in some main production areas.It is necessary to discriminate wheat YR and FHB at the regional scale to accurately locate the disease in space,conduct detailed disease severity monitoring,and scientific control.Four images on different dates were acquired from Sentinel-2,Landsat-8,and Gaofen-1 during the critical period of winter wheat,and 22 remote sensing features that characterize the wheat growth status were then calculated.Meanwhile,6 meteorological parameters that reflect the wheat phenological information were also obtained by combining the site meteorological data and spatial interpolation technology.Then,the principal components(PCs)of comprehensive remote sensing and meteorological features were extracted with principal component analysis(PCA).The PCs-based discrimination models were established to map YR and FHB damage using the random forest(RF)and backpropagation neural network(BPNN).The models’performance was verified based on the disease field truth data(57 plots during the filling period)and 5-fold cross-validation.The results revealed that the PCs obtained after PCA dimensionality reduction outperformed the initial features(IFs)from remote sensing and meteorology in discriminating between the two diseases.Compared to the IFs,the average area under the curve for both micro-average and macro-average ROC curves increased by 0.07 in the PCs-based RF models and increased by 0.16 and 0.13,respectively,in the PCs-based BPNN models.Notably,the PCs-based BPNN discrimination model emerged as the most effective,achieving an overall accuracy of 83.9%.Our proposed discrimination model for wheat YR and FHB,coupled with multi-source remote sensing images and meteorological data,overcomes the limitations of a single-sensor and single-phase remote sensing information in multiple stress discrimination in cloudy and rainy areas.It performs well in revealing the damage spatial distribution of the two diseases at a regional scale,providing a basis for detailed disease severity monitoring,and scientific prevention and control.
基金Supported by the National Natural Science Foundation of China(61971401)。
文摘In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide.This is equivalent to including an additional inductance-capacitance for energy storage,which realizes the slow-wave effect.A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth.In the frequency band between 8-12 GHz,the measured results show that the delay multiplier of the delay line reaches 4 times,i.e.,delay line’s delay time is 4 times larger than 50Ωmicrostrip line with same length.Furthermore,the delay fluctuation,i.e.,the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%,the insertion loss is less than-2.5 dB,and the return loss is less than-15 dB.Compared with the existing delay lines,the proposed delay line has the advantages of high delay efficiency,low delay error,wide bandwidth and low loss,which has good practical value and application prospects.
基金supported by the National Key Research and Development Program of China(No.2022YFA1203700)the National Natural Science Foundation of China(NSFC)(Nos.62405129 and 62035008)+1 种基金the University Research Project of Guangzhou Education Bureau(No.202235053)the Natural Science Foundation of Jiangsu Province(No.BK20241197).
文摘Multispectral imaging plays a crucial role in simultaneously capturing detailed spatial and spectral information,which is fundamental for understanding complex phenomena across various domains.Traditional systems face significant challenges,such as large volume,static function,and limited wavelength selectivity.Here,we propose an innovative dynamic reflective multispectral imaging system via a thermally responsive cholesteric liquid crystal based planar lens.By employing advanced photoalignment technology,the phase distribution of a lens is imprinted to the liquid crystal director.The reflection band is reversibly tuned from 450 nm to 750 nm by thermally controlling the helical pitch of the cholesteric liquid crystal,allowing selectively capturing images in different colors.This capability increases imaging versatility,showing great potential in precision agriculture for assessing crop health,noninvasive diagnostics in healthcare,and advanced remote sensing for environmental monitoring.
基金co-supported by the Tianjin Research innovation Project for Postgraduate Students,China(No.2022BKYZ039)the China Postdoctoral Science Foundation(No.2023M731788)the National Natural Science Foundation of China(No.62303246)。
文摘Global Navigation Satellite Systems(GNSSs)face significant security threats from spoofing attacks.Typical anti-spoofing methods rely on estimating the delays between spoofing and authentic signals using multicorrelator outputs.However,the accuracy of the delay estimation is limited by the spacing of the correlators.To address this,an innovative anti-spoofing method is introduced,which incorporates distinct coarse and refined stages for more accurate spoofing estimation.By leveraging the coarse delay estimates obtained through maximum likelihood estimation,the proposed method establishes the Windowed Sum of the Relative Delay(WSRD)statistics to detect the presence of spoofing signals.The iterative strategy is then employed to enhance the precision of the delay estimation.To further adapt to variations in the observation noise caused by spoofing intrusions and restore precise position,velocity,and timing solutions,an adaptive extended Kalman filter is proposed.This comprehensive framework offers detection,mitigation,and recovery against spoofing attacks.Experimental validation using datasets from the Texas Spoofing Test Battery(TEXBAT)demonstrates the effectiveness of the proposed anti-spoofing method.With 41 correlators,the method achieves a detection rate exceeding 90%at a false alarm rate of 10-5,with position or time errors below 15 m.Notably,this refined anti-spoofing approach shows robust detection and mitigation capabilities,requiring only a single antenna without the need for additional external sensors.These advancements can significantly contribute to the development of GNSS anti-spoofing measures.
基金supported by the Research Project of the Aerospace Information Research Institute,the Chinese Academy of Sciences(Grant Nos.E1Z1D101 and E2Z2D101)the Chinese Academy of Sciences(Grant No.E33310030D)the Guangzhou Basic and Applied Basic Research Foundation(Grant Nos.2023A04J0336 and 2023A04J0024).
文摘Deep ultraviolet coherent light,particularly at the wavelength of 193 nm,has become indispensable for semiconductor lithography.We present a compact solid-state nanosecond pulsed laser system capable of generating 193-nm coherent light at the repetition rate of 6 kHz.One part of the 1030-nm laser from the homemade Yb:YAG crystal amplifier is divided to generate 258 nm laser(1.2 W)by fourth-harmonic generation,and the rest is used to pump an optical parametric amplifier producing 1553 nm laser(700 mW).Frequency mixing of these beams in cascaded LiB_(3)O_(5) crystals yields a 193-nm laser with 70-mW average power and a linewidth of less than 880 MHz.By introducing a spiral phase plate to the 1553-nm beam before frequency mixing,we generate a vortex beam carrying orbital angular momentum.This is,to our knowledge,the first demonstration of a 193-nm vortex beam generated from a solid-state laser.Such a beam could be valuable for seeding hybrid ArF excimer lasers and has potential applications in wafer processing and defect inspection.
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.
基金Project supported by the National Natural Science Foundation of China (61988102)the Key-Area Research and Development Program of Guangdong Province(2019B090917007)the Science and Technology Planning Project of Guangdong Province (2019B090909011)。
文摘Bi_(2)YbO_(4)Cl with a fluorite layer structure belongs to the family of the bismuth rare-earth oxyhalides Bi_(2)REO_(4)X(X=Cl,B r,I).However,the synthesis and photoelectric properties of Bi_(2)YbO_(4)Cl have almost not been reported.In this work,Bi_(2)YbO_(4)Cl was synthesized using the solid-state method and the solvothermal method.Yb3+ions show a strong characteristic absorption peak at 980 nm,which was measured by ultraviolet-visible-near-infrared absorption spectra.The transient photoconductivity of Bi_(2)YbO_(4)Cl was obtained by time-resolved terahertz spectroscopy system under 400 and 800 nm laser excitations,respectively.The frequency-dependent transient photoconductivity analysis reveals the Drude-Smith behavior in Bi_(2)YbO_(4)Cl.Under photoexcitation,the hot charge carriers with a long relaxation lifetime and a carrier mobility of 48 cm^(2)/(V·s) are obtained.The synthesis of Bi_(2)YbO_(4)Cl is of great significance for the development of novel photocatalytic and photo harvesting materials with broad spectral response.
基金Supported by the National Natural Science Foundation of China(Nos.U23A2032,42006193)supported by the Hainan Provincial Excellent Talent Team Project(Space Observation of Deep-sea)。
文摘Internal solitary waves(ISWs)have considerable energy to drive the mixing of water masses in the Sulu Sea.The propagation speed is one of the critical parameters in quantifying the energy budget of the ISWs.We collected 1354 groups of ISWs’speeds from tandem satellite remote sensing images with temporal intervals shorter than 25 min and analyzed their spatial and multi-scale temporal variations in the Sulu Sea.We found that water depth plays an important role in modulating the spatial variation of wave speeds,which increase exponentially with water depth with a power of 0.26.Tidal currents,ocean stratification,background circulation,and climate affect the temporal variations of wave speeds from days to months or years.The fortnightly spring/neap tidal currents cause daily variations of wave speeds up to 40%by modulating the ISW amplitudes.In addition to the well-accepted results that monthly variations of wave speeds are related to density stratification,we found that enhanced stratification increases wave speeds,and the background circulation leads to a maximum decrease of 0.27 m/s in the linear counterparts of wave speed.Moreover,the averaged wave speed collected in October is lower than the corresponding linear one possibly due to some unknown dynamical processes or underestimation of background current.As for the interannual variations,we show that wave speed increases in La Niña years and decreases in El Niño years as a result of the climatic modulation on the depth of the maximum value of buoyancy frequency.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(SJCX23_1973)the National Natural Science Foundation of China(32172110,32071945)+7 种基金the Key Research and Development Program(Modern Agriculture)of Jiangsu Province,China(BE2022342-2,BE2020319)the Anhui Province Crop Intelligent Planting and Processing Technology Engineering Research Center Open Project,China(ZHKF04)the National Key Research and Development Program of China(2023YFD2300201,2023YFD1202200)the Special Funds for Scientific and Technological Innovation of Jiangsu Province,China(BE2022425)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)the Central Publicinterest Scientific Institution Basal Research Fund,China(JBYW-AII-2023-08)the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences(CAAS-CS-202201)the Special Fund for Independent Innovation of Agriculture Science and Technology in Jiangsu Province,China(CX(22)3112)。
文摘The wheat above-ground biomass(AGB)is an important index that shows the life activity of vegetation,which is of great significance for wheat growth monitoring and yield prediction.Traditional biomass estimation methods specifically include sample surveys and harvesting statistics.Although these methods have high estimation accuracy,they are time-consuming,destructive,and difficult to implement to monitor the biomass at a large scale.The main objective of this study is to optimize the traditional remote sensing methods to estimate the wheat AGBbased on improved convolutional features(CFs).Low-cost unmanned aerial vehicles(UAV)were used as the main data acquisition equipment.This study acquired image data acquired by RGB camera(RGB)and multi-spectral(MS)image data of the wheat population canopy for two wheat varieties and five key growth stages.Then,field measurements were conducted to obtain the actual wheat biomass data for validation.Based on the remote sensing indices(RSIs),structural features(SFs),and CFs,this study proposed a new feature named AUR-50(multi-source combination based on convolutional feature optimization)to estimate the wheat AGB.The results show that AUR-50 could estimate the wheat AGB more accurately than RSIs and SFs,and the average R^(2) exceeded 0.77.In the overwintering period,AUR-50_(MS)(multi-source combination with convolutional feature optimization using multispectral imagery)had the highest estimation accuracy(R^(2) of 0.88).In addition,AUR-50 reduced the effect of the vegetation index saturation on the biomass estimation accuracy by adding CFs,where the highest R^(2) was 0.69 at the flowering stage.The results of this study provide an effective method to evaluate the AGB in wheat with high throughput and a research reference for the phenotypic parameters of other crops.
基金sponsored by the National Natural Science Foundation of China(62121003,T2293730,T2293731,61960206012,62333020,and 62171434)the National Key Research and Development Program of China(2022YFC2402501 and 2022YFB3205602)the Major Program of Scientific and Technical Innovation 2030(2021ZD02016030)。
文摘Intracortical neural interfaces directly connect brain neurons with external devices to achieve high temporal resolution and spatially precise sampling of neural activity.When applied to freely moving animals,this technology provides in-depth insight into the underlying neural mechanisms for their movement and cognition in real-world scenarios.However,the application of implanted devices in freely moving animals is limited by restrictions on their behavioral freedom and physiologic impact.In this paper,four technological directions for ideal implantable neural interface devices are analyzed:higher spatial density,improved biocompatibility,enhanced multimodal detection of electrical/neurotransmitter signals,and more effective neural modulation.Finally,we discuss how these technological developments have been applied to freely moving animals to provide better insight into neuroscience and clinical medicine.
基金supported by the National Natural Science Foundation of China(No.42374177)。
文摘Passive surface wave imaging has been a powerful tool for near-surface characterization in urban areas,which extracts surface wave signals from ambient seismic noise and then estimates subsurface shear wave velocity by inversion of the measured phase velocity.The high-frequency(approximately>1 Hz)seismic noise fields in urban environments are dominantly induced by human activities such as the vehicle traffic.Traffic seismic sources are nonrandomly distributed in time and space.Applying standard interferometric techniques to recordings from these nonrandom noise sources makes the Green’s function liable to estimation errors.We analyze the influence of using nonrandom traffic seismic sources for surface wave imaging.With nonrandom traffic seismic sources in time,spurious signals are generated in the cross-correlation function.With nonrandom traffic seismic sources in space,surface-wave phase velocities could be overestimated in the dispersion measurement.We provide an overview of solutions for surface-wave imaging with nonrandom traffic seismic sources in time and space,aiming to improve the retrieval of high-frequency surface waves and achieve reliable results from ultrashort(tens of seconds)observations for near-surface characterization.
基金supported by STI 2030-Major Projects,No.2021ZD0201603(to JL)the Joint Foundation Program of the Chinese Academy of Sciences,No.8091A170201(to JL)+1 种基金the National Natural Science Foundation of China,Nos.T2293730(to XC),T2293731(to XC),T2293734(to XC),62471291(to YW),62121003(to XC),61960206012(to XC),62333020(to XC),and 62171434(to XC)the National Key Research and Development Program of China,Nos.2022YFC2402501(to XC),2022YFB3205602(to XC).
文摘Neuromodulation techniques effectively intervene in cognitive function,holding considerable scientific and practical value in fields such as aerospace,medicine,life sciences,and brain research.These techniques utilize electrical stimulation to directly or indirectly target specific brain regions,modulating neural activity and influencing broader brain networks,thereby regulating cognitive function.Regulating cognitive function involves an understanding of aspects such as perception,learning and memory,attention,spatial cognition,and physical function.To enhance the application of cognitive regulation in the general population,this paper reviews recent publications from the Web of Science to assess the advancements and challenges of invasive and non-invasive stimulation methods in modulating cognitive functions.This review covers various neuromodulation techniques for cognitive intervention,including deep brain stimulation,vagus nerve stimulation,and invasive methods using microelectrode arrays.The non-invasive techniques discussed include transcranial magnetic stimulation,transcranial direct current stimulation,transcranial alternating current stimulation,transcutaneous electrical acupoint stimulation,and time interference stimulation for activating deep targets.Invasive stimulation methods,which are ideal for studying the pathogenesis of neurological diseases,tend to cause greater trauma and have been less researched in the context of cognitive function regulation.Non-invasive methods,particularly newer transcranial stimulation techniques,are gentler and more appropriate for regulating cognitive functions in the general population.These include transcutaneous acupoint electrical stimulation using acupoints and time interference methods for activating deep targets.This paper also discusses current technical challenges and potential future breakthroughs in neuromodulation technology.It is recommended that neuromodulation techniques be combined with neural detection methods to better assess their effects and improve the accuracy of non-invasive neuromodulation.Additionally,researching closed-loop feedback neuromodulation methods is identified as a promising direction for future development.
基金supported by the Central Guiding Local Science and Technology Development Fund of Shandong-Yellow River Basin(No.YDZX2023019)Shandong Natural Science Foundation of China(Nos.ZR2020QF067 and ZR2023QD073)+6 种基金the Discipline Cluster Research Project of Qingdao University“Deep mining and intelligent prediction of multimodal big data for marine ecological disasters”(No.20240604)sourced from the International Argo Program and the national programs that contribute to it(https://argo.ucsd.edu)the CMEMS(http://marine.copernicus.eu/)the CDS(https://cds.climate.copernicus.eu/)the EMODnet(https://www.emodnet-chemistry.eu/)obtained from the ERA5(https://www.ecmwf.int)derived from the Glob Colour Project(http://globcolour.info).
文摘Oceanic dissolved oxygen(DO)concentration is crucial for assessing the status of marine ecosystems.Against the backdrop of global warming,DO shows a general decrease,posing a threat to the health of marine ecosystems.Therefore,there is an urgent need to develop advanced tools to characterize the spatio-temporal variations of three-dimensional(3D)DO.To address this challenge,this study introduces the Light Gradient Boosting Machine(Light-GBM),combining satellite remote sensing and reanalysis data with Biogeochemical Argo data to accurately reconstruct the 3D DO structure in the Mediterranean Sea from 2010 to 2022.Various environmental parameters are incorporated as inputs,including spatiotemporal features,meteorological characteristics,and ocean color properties.The LightGBM model demonstrates excellent performance on the testing dataset with R^(2) of 0.958.The modeled DO agrees better with in-situ measurements than products from numerical models.Using the Shapley Additive exPlanations method,the contributions of input features are assessed.Sea surface temperatures provide a correlation with DO at the sea surface,while spatial coordinates supplement the view of the ocean interior.Based on the reconstructed 3D DO structure,we identify an oxygen minimum zone in the western Mediterranean that expands continuously,reaching depths of approximately 300–800 m.The western Mediterranean exhibits a significant declining trend.This study enhances marine environmental evidence by proposing a precise and cost-effective approach for reconstructing 3D DO,thereby offering insights into the dynamics of DO variations under changing climatic conditions.
基金The State Grid Independent Research and Development Project(Project No.:CY1124SHF02)National Natural Science Foundation of China(Project No.:52320105003)the Fundamental Research Funds for the Central Universities(Project No.:E3ET1803)。
文摘This work uses advanced remote sensing to precisely extract hydrological information,supporting transmission network planning.High-resolution water body mapping lets designers optimize routes to avoid ecologically sensitive areas,achieving environmental protection,cost efficiency,and enhanced operational safety.The methodology provides a scalable,replicable framework for intelligent obstacle avoidance in power grid development,applicable to other regions and sectors with similar planning needs.
基金The National Key Research and Development Program of China under contract No.2021YFB3901304the National Natural Science Foundation of China under contract No.42842176181,42476173,and 42176179the Natural Science Foundation of Jiangsu Province under contract No.BK20211289.
文摘Chlorophyll a(Chl a)is a key photosynthetic pigment and an essential indicator of phytoplankton biomass.Accurate Chl a measurements are crucial for understanding marine biogeochemical processes.China launched the Chinese Ocean Color and Temperature Scanner(COCTS)aboard the HY-1D satellite in 2020,yet its Chl a products require further validation in complex coastal waters.This study assesses HY-1D Chl a products in the Bohai and Yellow Seas,two optically complex coastal regions,using in situ data collected during multiple cruises.Additionally,we compare HY-1D Chl a products with those from the Moderate Resolution Imaging Spectroradiometer(MODIS)and the Visible Infrared Imaging Radiometer Suite(VIIRS).We observed that although Chl a products from HY-1D are generally consistent with those from the MODIS and VIIRS in spatial distribution,there are still significant errors when compared with in situ data.Therefore,we developed a new blended algorithm to improve the accuracy of HY-1D Chl a products.The algorithm distinguishes between turbid and relatively clean waters using a classification index based on the ratio of remote sensing reflectance(R_(rs)(λ)).After the initial classification,we developed targeted algorithms based on the optical properties of different water bodies.The new model shows a significant improvement,reducing the mean absolute percentage error(MAPE)from 43.1%to 24.3%.Additionally,merging Chl a data from HY-1D,MODIS,and VIIRS maintains good accuracy,with HY-1D Chl a products significantly enhancing data coverage and robustness.This research provides important support for producing high-quality HY-1D Chl a products for coastal waters.
基金supported by a general project of the National Natural Science Foundation of China(42272346)a project initiated by the China Geological Survey(DD20230101).
文摘Zinc is recognized as a vital biological element for animals and plants.Both zinc deficiency and excess will cause damage to cells,and zinc deficiency in the human body may lead to severe health problems.Zinc deficiency has been identified as a global nutritional issue.Wheat,one of the most significant food crops for humans,is primarily planted in potentially zinc-deficient,calcareous soils in China.It proves to be a major global challenge to increase the zinc concentration in wheat crops to boost crop yields and improve human health.This study investigated the growth process of wheat in calcareous soils with various zinc concentrations using outdoor pot experiments and systematically explored the characteristics and mechanism of zinc transport in the soil-wheat system.The results indicate that the zinc concentrations in various wheat organs decreased in the order of roots,stems,and leaves in the jointing stage and in the order of seeds,roots,and stems in the mature stage.Overall,the zinc enrichment in various wheat organs decreased in the order of seeds,roots,stems,and leaves.In the case of zinc deficiency in soils,wheat roots exhibited elevated zinc availability in the rhizosphere by secreting phytosiderophores.This enhances the zinc uptake capacity of wheat roots.In the case of sufficient zinc supply from soils,chelated zinc formed with citric acid as the chelating ligand occurred stably in soils,contributing to enhanced utilization and uptake rates of zinc,along with elevated transport and enrichment capacities of zinc inside the plants.The results indicate that the zinc concentration in wheat seeds can be somewhat enhanced by regulating the background value of bioavailable zinc concentration in soils.A moderate zinc concentration gradient of 1.0 mg/kg is unfavorable for zinc accumulation in wheat seeds,while a high zinc concentration gradient of 6.0 mg/kg corresponds to the highest degree of zinc enrichment in wheat seeds.This study holds critical scientific significance for enhancing the zinc supply capacity of soils,increasing the zinc concentrations in wheat seeds,and,accordingly,addressing zinc deficiency in the human body.Additionally,this study offers a mechanistic reference and basis for research on the interplay between soils,plants,and human health.
基金funded by the National Natural Science Foundation of China(grant No.42376246)the Key Research and Development Project of Guangxi(grant No.GuikeAB24010046)the Joint Funds of the National Natural Science Foundation of China(grant No.U2268217).
文摘In the context of urbanization,air pollution has emerged as a significant environmental challenge.A thorough understanding of their transport pathways,especially at a national scale,is essential for environmental protection and policy-making.However,it remains partially elusive due to the constraints of available data and analytical methods.This study proposed a data-driven spatiotemporal correlation analysis method employing the Dynamic Time Warping(DTW).We represented the first comprehensive attempt to chart the long-term and nationwide transport pathways of PM_(2.5) utilizing an extensive dataset spanning from 2000 to 2021 across China,which is crucial for understanding long-term air pollution trends.Compared with traditional chemical transport models(CTMs),this data-driven method can generate transport pathways of PM_(2.5) without requiring extensive meteorological or emission data,and suggesting fundamentally consistent spatial distribution and trends.Our analysis reveals that China’s transport pathways are notably pronounced in the Northwest(34%of the total pathways in China),Southwest(22%),and North(21%)regions,with less significant pathways in the Northeast(10%)region and isolated occurrences elsewhere.Additionally,a notable decrease in the number of China’s PM_(2.5) transport pathways,similar to annual average concentrations,was observed after 2013,aligning with stricter environmental regulations.Furthermore,we have demonstrated the feasibility of applying our method to the transport pathways of other gaseous pollutants.The approach is effective in detecting and quantifying air pollutants’transport pathways,even in regions like the Northwest with limited monitoring infrastructure,which may aid in environmental decision-making.The study will notably improve the current understanding of air pollutants’transport process,providing a new perspective for studying the large-scale spatiotemporal correlations.
基金co-supported by the National Key Research and Development Program of China(No.2022YFF0503100)the Youth Innovation Project of Pandeng Program of National Space Science Center,Chinese Academy of Sciences(No.E3PD40012S).
文摘As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could range from kilometers to tens of kilometers, and even hundreds and thousands of kilometers. Therefore, it is crucial to develop effective long-range path planning for lunar rovers to meet the demands of lunar patrol exploration. This paper presents a hierarchical map model path planning method that utilizes the existing high-resolution images, digital elevation models and mineral abundance maps. The objective is to address the issue of the construction of lunar rover travel costs in the absence of large-scale, high-resolution digital elevation models. This method models the reference and semantic layers using the middle- and low-resolution remote sensing data. The multi-scale obstacles on the lunar surface are extracted by combining the deep learning algorithm on the high-resolution image, and the obstacle avoidance layer is modeled. A two-stage exploratory path planning decision is employed for long-distance driving path planning on a global–local scale. The proposed method analyzes the long-distance accessibility of various areas of scientific significance, such as Rima Bode. A high-precision digital elevation model is created using stereo images to validate the method. Based on the findings, it can be observed that the entire route spans a distance of 930.32 km. The route demonstrates an impressive ability to avoid meter-level impact craters and linear structures while maintaining an average slope of less than 8°. This paper explores scientific research by traversing at least seven basalt units, uncovering the secrets of lunar volcanic activities, and establishing ‘golden spike’ reference points for lunar stratigraphy. The final result of path planning can serve as a valuable reference for the design, mission demonstration, and subsequent project implementation of the new manned lunar rover.
