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Orthogonal waveform design with fractional programming on the ambiguity suppression of SAR systems

Science China(Information Sciences) 2024年第9期67卷 263-279页

作者： Yunkai DENG Yongwei ZHANG Zhimin ZHANG Wei WANG Heng ZHANG Department of Space Microwave remote sensing System Aerospace Information Research InstituteChinese Academy of Sciences

Waveform diversity(WD) represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities. Recently, WD techniques have been extensively explored for their potential ambiguity suppression within synthetic aperture radar(SAR) *** these, the alternate transmitting mode combined with orthogonal waveforms emerges as a particularly promising solution. This study focuses on optimizing the power spectrum density(PSD) of signals to design and generate an orthogonal waveform pair that achieves both a low cross-correlation-to-autocorrelation ratio(CAR) and satisfactory imaging performance. Initially, we construct a fractional programming model with convex constraints to minimize the CAR. To address this challenge, we introduce an iterative optimization procedure for the PSD variable, which sequentially reduces the CAR. Each optimization step can be efficiently solved using a quadratically constrained quadratic program, ensuring that the resulting computational complexity remains low. Building on the optimized PSD, we established a parametric piecewise linear model to generate an orthogonal waveform pair. This model not only maintains a low CAR but achieves satisfactory imaging performance in real-time applications. Consequently, this orthogonal waveform pair effectively suppresses range ambiguity in SAR systems. Finally, we demonstrated the practicability and effectiveness of the proposed orthogonal waveforms through detailed simulation experiments, specifically targeting ambiguity suppression in conventional quad-polarization SAR systems.

关键词： synthetic aperture radar (SAR) waveform diversity (WD) ambiguity suppression orthogonal waveform fractional programming power spectrum density (PSD)

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Multi-sensor multispectral reconstruction framework based on projection and reconstruction

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Science China(Information Sciences) 2024年第3期67卷 246-262页

作者： Tianshuai LI Tianzhu LIU Xian LI Yanfeng GU Yukun WANG Yushi CHEN School of Electronics and Information Engineering Harbin Institute of Technology Heilongjiang Province Key Laboratory of Space-Air-Ground Integrated Intelligent remote sensing

The scarcity and low spatial resolution of hyperspectral images(HSIs) have become a major problem limiting the application of the images. In recent years, spectral reconstruction(SR) has been applied to convert multispectral images(MSIs) with abundant quantities and high spatial resolution into HSIs. With the launch of several new multispectral(MS) satellites with a short repeat period, the simultaneous acquisition of images from multiple MS sensors in the same area is gradually becoming feasible. Unfortunately, existing SR methods only consider the reconstruction of the MSIs of a single sensor without considering using MSIs from different MS sensors to obtain a better construction effect through their complementary bands. However,multi-sensor SR is characterized by two problems: inconsistency in the amplitude information of real multisensor imaging and difficulty in the extraction of the complex correlations of bands from different *** solve these problems, this paper proposes a multi-sensor SR framework based on a two-step approach in which the problems of amplitude inconsistency and band information extraction are solved using an ideal projection network and an ideal multi-sensor SR network, respectively. The effectiveness of the proposed method is verified by experiments on three datasets.

关键词： spectral reconstruction spectral superresolution hyperspectral image multispectral image neural networks multi-sensor

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Nonlinear characteristics of torsional stiffness of a coilable mast with triangular section

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Chinese Journal of Aeronautics 2024年第10期37卷 313-324页

作者： Yu LIU Liang SUN Hai HUANG Shenyan CHEN Weipeng LI Xurui ZHAO School of Astronautics Beihang UniversityBeijing 100191China institute of remote sensing Satellite China Academy of Space TechnologyBeijing 100094China

With numerous applications coilable masts in high-precision astronomical observations,such as X-ray source observations,it is important to investigate mast *** date,there have been many studies on the bending stiffness of coilable masts,but few studies on their torsional stiffness,especially regarding the nonlinear characteristics of torsional stiffness of coilable masts under large torsional *** this paper,a nonlinear analysis method is presented to examine the torsional stiffness of coilable masts with triangular *** on the second-order bending buckling hypothesis of battens under large torsion deformation,the nonlinear relationship between torsional torque and torsional angle is obtained by analyzing torsional deformation and force of coilable *** method is used to analyze the torsional stiffness nonlinearity of a certain type of coilable mast which will be used in a practical application in the future and the results are verified by simulation and *** comparison results show that the error is within the acceptable range,which proves the effectiveness of the proposed method.

关键词： Coilable mast Torsion testing Torsional stiffness nonlinearity Torsional deformation Torsion simulation

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Spatiotemporal changes in sunshine duration and its influential factors in Chongqing,China from 1961 to 2020

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Journal of Mountain Science 2024年第6期21卷 2005-2024页

作者： LI Jun XIA Hongxuan JIANG Jinge XU Weifeng WEN Di XU Junfeng College of Geography and Tourism Chongqing Normal UniversityChongqing 401331China Key Laboratory of GIS Application of Chongqing Chongqing 401331China Chongqing Key Laboratory of Earth Surface Processes and Environmental remote sensing in Three Gorges Reservoir area Chongqing 401331China institute of remote sensing and Earth Sciences School of Institute of Remote Sensing and Earth SciencesSchool of ScienceHangzhou Normal UniversityHangzhou 311121China

The surface solar radiation in most parts of the world has undergone a phenomenon known as global dimming and brightening,characterized by an initial decrease followed by an *** a result,the sunshine duration(SD)has decreased in the past 60 *** the backdrop of global dimming and brightening,SD has decreased to varying degrees in many regions of *** the observed data of SD,cloud amount(total cloud amount and low cloud amount,abbreviated as TCA and LCA),precipitation,and relative humidity(RH)from 34 meteorological stations in Chongqing during the period of 1961-2020,along with a digital elevation model(DEM)with a resolution of 90 m,this study analyzed the spatiotemporal variations and influencing factors of *** analysis employed methods such as linear regression,Mann-Kendall test,wavelet transformation,and DEM-based possible SD distributed *** results showed that the annual SD in Chongqing has significantly decreased over the last 60 years,with a decreasing interannual trend rate(ITR)of 40.4 h/*** for no obvious trend in spring,SD decreased significantly in summer,autumn and winter at the ITR of 21.1 h/10a,8.5 h/10a and 7.5 h/10a,*** abrupt decrease in the annual SD was found in *** difference before and after the abrupt decrease was 177.7 *** difference before and after the abrupt decrease was 177.7 *** annual SD possessed the oscillation period of *** spatial heterogeneity of the mean annual SD during the last 60 years was *** distribution of SD in Chongqing is high in the northeast and low in the *** addition,about 73%of the total area in Chongqing showed a significant and very significant decreasing *** regions with significant changes are mainly concentrated in the regions with altitudes of 200~1000 *** increasing LCA was the main cause of the decrease of the annual SD in the regions with 200-400 m altitude decreased the most and changed the *** LCA is the prim

关键词： Sunshine duration Spatiotemporal changes Mann-Kendall test Wavelet analysis Geodetector model

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A novel method for calculating broadband electrical performance of high-speed aircraft radome under thermo-mechanical-electrical coupling

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Chinese Journal of Aeronautics 2024年第9期37卷 463-474页

作者： Jianmin JI Jianhua REN Xunya JIANG Wei WANG Huilong YU Kai YIN Bo CHEN Beijing institute of remote sensing Equipment Beijing 100854China Shanghai Dong Jun Information and Technology Co.Ltd Shanghai 200050China

The electrical performance of radomes on high-speed aircraft can be influenced by the thermal and mechanical loads produced during high-speed flight,which can affect the detection dis-tance and accuracy of the guidance *** paper presents a new method that uses the Finite Difference Time Domain(FDTD)method to calculate the electrical performance of radomes under Thermo-Mechanical-Electrical(TME)*** method can accurately characterize the effects of material dielectric temperature drift and structural deformation on the electrical performance of the radome under flight conditions,enabling high-precision full-wave calculations of the broadband electrical performance of the *** method initiates by utilizing a Finite Element Grid Model(FE-GM)of the radome to sequentially acquire the radome's response temperature field and structural deformation field through thermal and mechanical ***,spatial mapping techniques are developed to accurately incorporate the dielectric temperature drift and structural deformation of the radome into its Yee grid Electromagnetic(EM)simulation model.A verification case was designed to test the proposed method,and the results confirmed its high computational ***,the effectiveness and necessity of the method were further demonstrated by analyzing the electrical performance of a fused silica ceramic radome used on a high-speed aircraft.

关键词： High-speed aircraft Radomes Thermo-Mechanical-Electrical(TME)coupling Finite Difference Time Domain(FDTD)method Spatial mapping

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Integrating remote sensing and 3-PG model to simulate the biomass and carbon stock of Larix olgensis plantation

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Forest Ecosystems 2024年第4期11卷 543-555页

作者： Yu Bai Yong Pang Dan Kong Key Laboratory of National Forestry and Grassland Administration on Forestry remote sensing and Information System Institute of Forest Resource Information

Accurate estimations of biomass and its temporal dynamics are crucial for monitoring the carbon cycle in forest ecosystems and assessing forest carbon sequestration *** studies have shown that integrating process-based models(PBMs)with remote sensing data can enhance simulations from stand to regional scales,significantly improving the ability to simulate forest growth and carbon stock ***,the utilization of PBMs for large-scale simulation of larch carbon storage distribution is still *** this study,we applied the parameterized 3-PG(Physiological Principles Predicting Growth)model across the Mengjiagang Forest Farm(MFF)to make broad-scale predictions of the biomass and carbon stocks of Larix olgensis *** model was used to simulate average diameter at breast height(DBH)and total biomass,which were later validated with a wide range of observation data including sample plot data,forest management inventory data,and airborne laser scanning *** results showed that the 3-PG model had relatively high accuracy for predicting both DBH and total biomass at stand and regional scale,with determination coefficients ranging from 0.78 to *** on the estimation of total biomass,we successfully produced a carbon stock map of the Larix olgensis plantation in MFF with a spatial resolution of 20 m,which helps with relevant management *** findings indicate that the integration of 3-PG model and remote sensing data can well predict the biomass and carbon stock at regional and even larger *** addition,this integration facilitates the evaluation of forest carbon sequestration capacity and the development of forest management plans.

关键词： 3-PG model Larch Biomass Carbon stock ALS

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A new monitoring index for ecological vulnerability and its application in the Yellow River Basin,China from 2000 to 2022

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Journal of Arid Land 2024年第9期16卷 1163-1182页

作者： GUO Bing XU Mei ZHANG Rui LUO Wei School of Civil Engineering and Geomatics Shandong University of TechnologyZibo 255000China Key Laboratory of remote sensing of Gansu Province Heihe Remote Sensing Experimental Research StationNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China North China institute of Aerospace Engineering Langfang 065000China

The ecological environment of the Yellow River Basin has become more fragile under the combined action of natural and manmade ***,the change mechanisms of ecological vulnerability in different sub-regions and periods vary,and the reasons for this variability are yet to be ***,in this study,we proposed a new remote sensing ecological vulnerability index by considering moisture,heat,greenness,dryness,land degradation,and social economy indicators and then analyzed and disclosed the spatial and temporal change patterns of ecological vulnerability of the Yellow River Basin,China from 2000 to 2022 and its driving *** results showed that the newly proposed remote sensing ecological vulnerability index had a high accuracy,at 86.36%,which indicated a higher applicability in the Yellow River *** 2000 to 2022,the average remote sensing ecological vulnerability index of the Yellow River Basin was 1.03,denoting moderate vulnerability *** intensive vulnerability area was the most widely distributed,which was mostly located in the northern part of Shaanxi Province and the eastern part of Shanxi *** 2000 to 2022,the ecological vulnerability in the Yellow showed an overall stable trend,while that of the central and eastern regions showed an obvious trend of *** gravity center of ecological vulnerability migrated southwest,indicating that the aggravation of ecological vulnerability in the southwestern regions was more severe than in the northeastern regions of the *** dominant single factor of changes in ecological vulnerability shifted from normalized difference vegetation index(NDVI)to temperature from 2000 to 2022,and the interaction factors shifted from temperature∩NDVI to temperature∩precipitation,which indicated that the global climate change exerted a more significant impact on regional *** above results could provide decision support for the ecological protection and restoration of the Y

关键词： ecological vulnerability spatio-temporal pattern gravity center migration trajectory interaction factors geodetector green index q-value

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Apatite Fission-Track Thermochronology in the Tamusu Area,Bayingobi Basin,NW China,and its Geological Significance

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 585-601页

作者： TONG Qinlong QIN Mingkuan YE Fawang CNNC Beijing Research institute of Uranium Geology National Key Laboratory of Remote Sensing Information and Image Analysis TechnologyBeijing 100029China

The Bayingobi basin is located in the middle of Central Asia Orogenic Belt,at the intersection of Paleo-Asian Ocean and Tethys Ocean,as well as the junction of multiple tectonic *** unique tectonic setting underpins the basin's intricate history of tectonic *** unravel the multifaceted tectono-thermal evolution within the southwestern region of the basin and to elucidate the implications of sandstone-hosted uranium mineralization,granitic and clastic rock samples were collected from the Zongnai *** and Yingejing depression,and apatite fission track(AFT)dating and thermal history simulation analysis were *** dating findings reveal that the apparent ages of all samples fall within the range of 244 Ma to 112 *** particular,the bedrock of the Zongnai *** Jurassic detrital apatite fission tracks have undergone complete annealing,capturing the uplift-cooling ***,the AFT ages of Cretaceous detrital rocks are either equivalent to or notably exceed the age of sedimentary strata,signifying the cooling age of the provenance.A comprehensive examination of AFT ages and palaeocurrent direction analyses suggests that the Cretaceous source in the Tamusu area predominantly originated from the central and southern sectors of the Zongnai ***,at a certain juncture during the Late Early Cretaceous,the Cretaceous provenance expanded to include the northern part of the Zongnai *** on the results of thermal history simulations and previous studies,it is considered that the Tamusu area has undergone four distinct tectonic uplift events since the Late *** first is the Late Permian to Early Triassic(260-240 Ma),which is associated with the closure of the Paleo-Asian Ocean and the accretionary orogeny within the Alxa *** second uplift event took place in the Early Jurassic(190-175 Ma)and corresponded to intraplate orogeny following the closure of the Paleo-Asian *** third uplift event is the Lat

关键词： apatite fission-track tectono-thermal history sandstone-hosted uranium deposit Bayingobi basin Central Asian Orogenic Belt

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Long-term(2013-2022)mapping of winter wheat in the North China Plain using Landsat data:classification with optimal zoning strategy

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Big Earth Data 2024年第3期8卷 494-521页

作者： Yifei Liu Xuehong Chen Jin Chen Yunze Zang Jingyi Wang Miao Lu Liang Sun Qi Dong Bingwen Qiu Xiufang Zhu State Key Laboratory of remote sensing Science Institute of Remote Sensing Science and EngineeringFaculty of Geographical ScienceBeijing Normal UniversityBeijingChina Beijing Engineering Research Center for Global Land remote sensing Products Institute of Remote Sensing Science and EngineeringFaculty of Geographical ScienceBeijing Normal UniversityBeijingChina State Key Laboratory of Crop Gene Resources and Breeding Institute of Crop SciencesChinese Academy of Agricultural Sciences(CAAS)BeijingChina State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China Institute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijingChina Key Laboratory of Spatial Data Mining&Information Sharing of Ministry of Education Academy of Digital China(Fujian)Fuzhou UniversityFuzhouChina

security and formulating agricultural *** data are the only available source for long-term winter wheat mapping in the North China Plain due to the fragmented landscape in this *** various methods,such as index-based methods,curve similarity-based methods and machine learning-based methods,have been developed for winter wheat mapping based on remote sensing,the former two often require satellite data with high temporal resolution,which are unsuitable for Landsat data with sparse *** learning is an effective method for crop classification using Landsat ***,applying machine learn-ing for winter wheat mapping in the North China Plain encounters two main issues:1)the lack of adequate and accurate samples for classifier training;and 2)the difficulty of training a single classifier to accomplish the large-scale crop mapping due to the high spatial heterogeneity in this *** address these two issues,we first designed a sample selection rule to build a large sample set based on several existing crop maps derived from recent Sentinel data,with specific consideration of the confusion error between winter wheat and winter rapeseed in the available crop ***,we developed an optimal zoning method based on the quadtree region splitting algorithm with classification feature consistency criterion,which divided the study area into six subzones with uni-form classification *** each subzone,a specific random forest classifier was trained and used to generate annual winter wheat maps from 2013 to 2022 using Landsat 8 OLI *** sample validation confirmed the high accuracy of the produced maps,with an average overall accuracy of 91.1%and an average kappa coefficient of 0.810 across different *** derived winter wheat area also has a good correlation(R2=0.949)with census area at the provincial *** results underscore the reliability of the produced annual winter wheat *** experiments demonstrate that

关键词： Winter wheat mapping Landsat machine learning North China Plain optimal zoning

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Time series analysis of L-band PALSAR-2 images in Istanbul and Kocaeli,Turkey

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Big Earth Data 2024年第3期8卷 467-493页

作者： Sadra Karimzadeh Abdullah Can Zulfikar Masashi Matsuoka Department of remote sensing and GIS University of TabrizTabrizIran Department of Architecture and Building Engineering Tokyo Institute of TechnologyYokohamaJapan Disaster Management institute Istanbul Technical UniversityMaslakIstanbulTurkey

ABSTRACT Conducting long measurements of infrastructure deformation is a critical engineering *** methods are both timeconsuming and expensive,limiting their use for large-scale *** synergy of synthetic aperture radar(SAR)and geographic information systems(GIS)offers a complementary *** study focuses on the feasibility of using time series analysis of L-band PALSAR-2 images to discover land displacements in Istanbul and Kocaeli,significant industrial and residential areas in ***-2 phase and intensity information were *** phase analysis,14 L-band images from 2014 to 2021 were taken into *** baseline subset(SBAS)analysis was performed using 44 pairs,and results of the velocity,coherence and back-scattering values are *** of all pairs and their correlations were *** Component Analysis(PCA)reduced the dimension of coherence pairs,enhancing feature extraction and the final geocoded velocity map revealed a fastest subsidence rate of−58 mm/yr and a mean subsidence of−20 mm/*** findings were confirmed through mean vertical velocity from Sentinel-1 datasets and field *** results showed that immature land subsidence in the mentioned areas are growing slowly,which can be taken as a serious risk in future.

关键词： InSAR time series PALSAR-2 SAR intensity infrastructure deformation

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