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| 1 | Solid-state additive manufacturing and repairing by cold spraying:A review显示文摘High-performance metal additive manufacturing(AM) has been extensively investigated in recent year because of its unique advantages over traditional manufacturing processes. AM has been applied to form complex components of Ti, Fe or Ni alloys. However, for other nonferrous alloys such as Al alloys, Mg alloys and Cu alloys, AM may not be appropriate because of its melting nature during processing by laser electron beam, and/or arc. Cold spraying(CS) has been widely accepted as a promising solid-state coating technique in last decade for its mass production of high-quality metals and alloys, and/or metal matrix composites coatings. It is now recognized as a useful and powerful tool for AM, but the related research work has just started. This review summarized the literature on the state-of-the-art and problems for C as an AM and repairing technique. | Wenya Li Kang Yang Shuo Yin Xiawei Yang Yaxin Xu Rocco Lupoi | 2018 | Journal of Materials Science & Technology2018，34，3： | 35 |
| 2 | Spin-decoupled metasurface for simultaneous detection of spin and orbital angular momenta via momentum transformation显示文摘With inherent orthogonality,both the spin angular momentum(SAM)and orbital angular momentum(OAM)of photons have been utilized to expand the dimensions of quantum information,optical communications,and information processing,wherein simultaneous detection of SAMs and OAMs with a single element and a single-shot measurement is highly anticipated.Here,a single azimuthal-quadratic phase metasurface-based photonic momentum transformation(PMT)is illustrated and utilized for vortex recognition.Since different vortices are converted into focusing patterns with distinct azimuthal coordinates on a transverse plane through PMT,OAMs within a large mode space can be determined through a single-shot measurement.Moreover,spin-controlled dual-functional PMTs are proposed for simultaneous SAM and OAM sorting,which is implemented by a single spin-decoupled metasurface that merges both the geometric phase and dynamic phase.Interestingly,our proposed method can detect vectorial vortices with both phase and polarization singularities,as well as superimposed vortices with a certain interval step.Experimental results obtained at several wavelengths in the visible band exhibit good agreement with the numerical modeling.With the merits of ultracompact device size,simple optical configuration,and prominent vortex recognition ability,our approach may underpin the development of integrated and high-dimensional optical and quantum systems. | Yinghui Guo Shicong Zhang Mingbo Pu Qiong He Jinjin Jin Mingfeng Xu Yaxin Zhang Ping Gao Xiangang Luo | 2021 | Light(Science & Applications)2021，10，4： | 14 |
| 3 | Deposition of FeCoNiCrMn high entropy alloy(HEA) coating via cold spraying显示文摘High entropy alloys(HEAs) are of great interest in the community of materials science and engineering due to their unique phase structure. They are constructed with five or more principal alloying elements in equimolar or near-equimolar ratio. Therefore, HEAs can derive their performance from multiple principal elements rather than a single element. In this work, solid-state cold spraying(CS) was applied for the first time to produce FeCoNiCrMn HEA coating. The experimental results confirm that CS can be used to produce a thick HEA coating with low porosity. As a low-temperature deposition process, CS completely retained the HEA phase structure in the coating without any phase transformation. The characterization also reveals that the grains in the CSed HEA coating had experienced significant refinement as compared to those in the as-received HEA powder due the occurrence of dynamic recrystallization at the highly deformed interparticle region. Due to the increased dislocation density and grain boundaries,CSed HEA coating was much harder than the as-received powder. The tribological study shows that the CSed FeCoNiCrMn HEA coating resulted in lower wear rate than laser cladded HEA coatings. | Shuo Yin Wenya Li Bo Song Xingchen Yan Min Kuang Yaxin Xu Kui Wen Rocco Lupoi | 2019 | Journal of Materials Science & Technology2019，35，6： | 13 |
| 4 | Plasma metabolomic and lipidomic alterations associated with COVID-19显示文摘The pandemic of the coronavirus disease 2019(COVID-19)has become a global public health crisis.The symptoms of COVID-19 range from mild to severe,but the physiological changes associated with COVID-19 are barely understood.In this study,we performed targeted metabolomic and lipidomic analyses of plasma from a cohort of patients with COVID-19 who had experienced different symptoms.We found that metabolite and lipid alterations exhibit apparent correlation with the course of disease in these patients,indicating that the development of COVID-19 affected their whole-body metabolism.In particular,malic acid of the TCA cycle and carbamoyl phosphate of the urea cycle result in altered energy metabolism and hepatic dysfunction,respectively.It should be noted that carbamoyl phosphate is profoundly down-regulated in patients who died compared with patients with mild symptoms.And,more importantly,guanosine monophosphate(GMP),which is mediated not only by GMP synthase but also by CD39 and CD73,is significantly changed between healthy subjects and patients with COVID-19,as well as between the mild and fatal cases.In addition,dyslipidemia was observed in patients with COVID-19.Overall,the disturbed metabolic patterns have been found to align with the progress and severity of COVID-19.This work provides valuable knowledge about plasma biomarkers associated with COVID-19 and potential therapeutic targets,as well as an important resource for further studies of the pathogenesis of COVID-19. | Di Wu Ting Shu Xiaobo Yang Jian-Xin Song Mingliang Zhang Chengye Yao Wen Liu Muhan Huang Yuan Yu Qingyu Yang Tingju Zhu Jiqian Xu Jingfang Mu Yaxin Wang Hong Wang Tang Tang Yujie Ren Yongran Wu Shu-Hai Lin Yang Qiu Ding-Yu Zhang You Shang Xi Zhou | 2020 | National Science Review2020，7，7： | 9 |
| 5 | Crosstalk-free achromatic full Stokes imaging polarimetry metasurface enabled by polarization-dependent phase optimization显示文摘Imaging polarimetry is one of the most widely used analytical technologies for object detection and analysis.To date,most metasurface-based polarimetry techniques are severely limited by narrow operating bandwidths and inevitable crosstalk,leading to detrimental effects on imaging quality and measurement accuracy.Here,we propose a crosstalkfree broadband achromatic full Stokes imaging polarimeter consisting of polarization-sensitive dielectric metalenses,implemented by the principle of polarization-dependent phase optimization.Compared with the single-polarization optimization method,the average crosstalk has been reduced over three times under incident light with arbitrary polarization ranging from 9μm to 12μm,which guarantees the measurement of the polarization state more precisely.The experimental results indicate that the designed polarization-sensitive metalenses can effectively eliminate the chromatic aberration with polarization selectivity and negligible crosstalk.The measured average relative errors are 7.08%,8.62%,7.15%,and 7.59%at 9.3,9.6,10.3,and 10.6μm,respectively.Simultaneously,the broadband full polarization imaging capability of the device is also verified.This work is expected to have potential applications in wavefront detection,remote sensing,light-field imaging,and so forth. | Yaxin Zhang Mingbo Pu Jinjin Jin Xinjian Lu Yinghui Guo Jixiang Cai Fei Zhang Yingli Ha Qiong He Mingfeng Xu Xiong Li Xiaoliang Ma Xiangang Luo | 2022 | Opto-Electronic Advances2022，5，11： | 6 |
| 6 | Characterizations and anisotropy of cold-spraying additive-manufactured copper bulk显示文摘In this study, thick copper coatings were deposited by cold spraying(CS) as an additive manufacturing(AM) method. The interfacial microstructure evolution and mechanical behavior were investigated for the as-sprayed and annealed conditions. In addition, experiments together with numerical simulations were employed to study the recrystallization in different stages. Finally, the mechanical anisotropy of the CSed deposit was tested for the first time, being important to the applications of CS-AM. Results show that there exist two stages of recrystallization in the spraying and annealing processes. Heat treatment has a significant effect on mechanical properties, i.e., the tensile strength increases by 34.2% while microhardness decreases by 43.6%. The mechanical anisotropy analysis shows that the tensile strengths of different directions are completely different and show some regular changes. | Kang Yang Wenya Li Xueping Guo Xiawei Yang Yaxin Xu | 2018 | Journal of Materials Science & Technology2018，34，9： | 5 |
| 7 | Multicenter phaseⅡstudy of apatinib single or combination therapy in HER2-negative breast cancer involving chest wall metastasis显示文摘Objective:Breast cancer(BC)with chest wall metastasis(CWM)usually shows rich neovascularization.This trial explored the clinical effect of apatinib on human epidermal growth factor receptor 2(HER2)-negative advanced BC involving CWM.Methods:This trial involved four centers in China and was conducted from September 2016 to March 2020.Patients received apatinib 500 mg/d[either alone or with endocrine therapy if hormone receptor-positive(HR+)]until disease progression or unacceptable toxicity.Progression-free survival(PFS)was the primary endpoint.Results:We evaluated 26 patients for efficacy.The median PFS(mPFS)and median overall survival(mOS)were4.9[range:2.0-28.5;95%confidence interval(95%CI):2.1-8.3]months and 18(range:3-55;95%CI:12.9-23.1)months,respectively.The objective response rate(ORR)was 42.3%(11/26),and the disease-control rate was76.9%(20/26).In the subgroup analysis,HR+patients compared with HR-negative patients had significantly improved mPFS of 7.0(95%CI:2.2-11.8)months vs.2.3(95%CI:1.2-3.4)months,respectively(P=0.001);and mPFS in patients without or with chest wall radiotherapy was 6.4(95%CI:1.6-19.5)months vs.3.0(95%CI:1.3-4.6)months,respectively(P=0.041).In the multivariate analysis,HR+status was the only independent predictive factor for favorable PFS(P=0.014).Conclusions:Apatinib was highly effective for BC patients with CWM,especially when combined with endocrine therapy.PFS improved significantly in patients with HR+status who did not receive chest wall radiotherapy.However,adverse events were serious and should be carefully monitored from the beginning of apatinib treatment. | Huiping Li Cuizhi Geng Hongmei Zhao Hanfang Jiang Guohong Song Jiayang Zhang Yaxin Liu Xinyu Gui Jing Wang Kun Li Zhongsheng Tong Fangyuan Zhao Junlan Yang Guoliang Chen Qianyu Liu Xu Liang | 2021 | Chinese Journal of Cancer Research2021，33，2： | 4 |
| 8 | Hot deformation behavior and microstructure evolution of the laser solid formed TC4 titanium alloy显示文摘Hot compressive experiments of the laser solid formed(LSFed)TC4 titanium alloy were conducted at a wide temperature range of 650-950℃and strain rate of 0.01-10 s^(-1).The Arrheniustype constitutive models of the LSFed TC4 alloy were established at the temperature range of 800-950℃and of 650-800℃,respectively.The average relative error between the predicted stresses and experimental values in those two temperature ranges are 10.4%and 8.3%,respectively,indicating that the prediction models constructed in this paper are in a good agreement with experimental data.Processing maps were established by the principle of dynamic materials modeling on the basis of the data achieved from the hot compression experiments.The processing parameters corresponding to the stable and unstable regions of material deformation can be determined from the processing maps.The microstructure evolution of the stable and unstable regions of the samples after tests were observed.Finally,the effect of hot compressive parameters on the microstructure were investigated to research the dynamic recrystallization and the texture of the deformed LSFed TC4 alloy. | Xiawei YANG Yanying WANG Xiurong DONG Chong PENG Baijin JI Yaxin XU Wenya LI | 2021 | Chinese Journal of Aeronautics2021，34，5： | 3 |
| 9 | Optimization of cold-sprayed AA2024/Al_2O_3 metal matrix composites via friction stir processing: Effect of rotation speeds显示文摘In this study, friction stir processing(FSP) was employed to modify cold-sprayed(CSed) AA2024/Al_2 O_3 metal matrix composites(MMCs). Three different rotation speeds with a constant traverse speed were used for FSP. Microstructural analysis of the FSPed specimens reveals significant Al_2 O_3 particle refinement and improved particle distribution over the as-sprayed deposits. After FSP, a microstructural and mechanical gradient MMC through the thickness direction was obtained. Therefore, a hybrid technique combining these two solid-state processes, i.e. CS and FSP, was proposed to produce functionally gradient deposits. The Guinier-Preston-Bagaryatskii zone was dissolved during FSP, while the amounts at different rotation speeds were approximately the same, which is possibly due to the excellent thermal conductivity of the used Cu substrate. Mechanical property tests confirm that FSP can effectively improve the tensile performance and Vickers hardness of CSed AA2024/Al_2 O_3 MMCs. The properties can be further enhanced with a larger rotation speed with a maximum increase of 25.9% in ultimate tensile strength and27.4% in elongation at 1500 rpm. Friction tests show that FSP decreases the wear resistance of CSed MMCs deposits due to the breakup of Al_2 O_3 particles. The average values and fluctuations of friction coefficients at different rotation speeds vary significantly. | Kang Yang Wenya Li Chunjie Huang Xiawei Yang Yaxin Xu | 2018 | Journal of Materials Science & Technology2018，34，11： | 3 |
| 10 | Using Artificial Neural Networks for Energy Regulation Based Variable-speed Electrohydraulic Drive显示文摘In the energy regulation based varibable-speed electrohydraulic drive system, the supply energy and the demanded energy, which will affect the control performance greatly, are crucial. However, they are hard to be obtained via conventional methods for some reasons. This paper tries to a new route: the definitive numerical values of the supply energy and the demanded energy are not required, except for their relationship which is called energy state. A three-layer back propagation(BP) neural network was built up to act as an energy analysis unit to deduce the energy state. The neural network has three inputs: the reference displacement, the actual displacement of cylinder rod and the system flowrate supply. The output of the neural network is energy state. A Chebyshev type II filter was designed to calculate the cylinder speed for the estimation of system flowrate supply. The training and testing samples of neural network were collected by the system accurate simulation model. After off-line training, the neural network was tested by the testing data. And the testing result demonstrates that the designed neural network was successful. Then, the neural network acts as the energy analysis unit in real-time experiments of cylinder position control, where it works efficiently under square-wave and sine-wave reference displacement. The experimental results validate its feasibility and adaptability. Only a position sensor and some pressure sensors, which are cheap and have quick dynamic response, are necessary for the system control. And the neural network plays the role of identifying the energy state. | XU Ming JIN Bo YU Yaxin SHEN Haikuo LI Wei | 2010 | Chinese Journal of Mechanical Engineering2010，23，3： | 3 |
| 11 | Electrochemical characterization and microstructure of cold sprayed AA5083/Al_(2)O_(3) composite coatings显示文摘This work focused on the role of Al_(2)O_(3) particles in the corrosion behavior of cold sprayed AA5083 aluminum alloy matrix composite(Al-MMC)coatings.The electrochemical characterization of the coatings was investigated in a 3.5 wt.%NaCl solution as a function of time.The results show that fragmentation of Al_(2)O_(3) particles is not clearly observed in the case of AA5083/20 vol.%Al_(2)O_(3) coating,while the broken Al_(2)O_(3) particles can be seen clearly in AA5083/40 vol.%Al_(2)O_(3) and AA5083/60 vol.%Al_(2)O_(3) coatings.The addition of 20 vol.%Al_(2)O_(3) particles yield the coating with the lowest porosity,and different volume fractions of Al_(2)O_(3)in the feedstock have important effects on the electrochemical behavior of composite coatings.The Al-MMC coating reinforced with 20 vol.%Al_(2)O_(3) particles exhibits the highest Ecorrand the lowest icorrcompared with the other conditions.The order of current density is as follows:AA5083/20vol.%Al_(2)O_(3) | Xiawei Yang Wenya Li Siqi Yu Yaxin Xu Kaiwei Hu Yaobang Zhao | 2020 | Journal of Materials Science & Technology2020，59，24： | 3 |
| 12 | Pt-Re/rGO bimetallic catalyst for highly selective hydrogenation of cinnamaldehyde to cinnamylalcohol显示文摘In the present work, a series of Pt-based catalysts, alloyed with a second metal, i.e., Re, Sn, Er, La, and Y, and supported on activated carbon, ordered mesoporous carbon, N-doped mesoporous carbon or reduced graphene oxide(rGO), have been developed for selective hydrogenation of cinnamaldehyde to cinnamylalcohol. Re and rGO were proved to be the most favorable metal dopant and catalyst support, respectively. Pt_(50) Re_(50)/rGO showed the highest cinnamylalcohol selectivity of 89% with 94% conversion of cinnamaldehyde at the reaction conditions of 120 °C, 2.0 MPaH_2 and 4 h. | Zuojun Wei Xinmiao Zhu Xiaoshuang Liu Haiqin Xu Xinghua Li Yaxin Hou Yingxin Liu | 2019 | Chinese Journal of Chemical Engineering2019，27，2： | 2 |
| 13 | Heterostructured Nitrogen and Sulfur co-Doped Black TiO2/g-C3N4 Photocatalyst with Enhanced Photocatalytic Activity显示文摘Conventional titanium dioxide(TiO2)photocatalyst could absorb only ultraviolet light due to its wide bandgap.In this paper,black TiO2 with narrow bandgap was prepared by introducing oxygen vacancies.Meanwhile.nitrogen(N)and sulfur(S)elements were doped to further broaden the visible light response range of TiOx(NS-BT),and then heterostructured N.S-doped black TiOz/g-C3Na(CN/NS-BT)was successfully constructed by easily accessible route.The formation of CN/NS-BT heteroiunction structure increased the generation and separation efficiency of photogenerated electron-hole pairs,as well as accelerated the transfer rate of the carriers.The as-prepared CN/NS-BT exhibited excellent photocatalytic performance towards the degradation of Rhodamine B(RhB)under visible light irradiation with satisfactory stability.The apparent reaction rate constant of CN/NS-BT(0.0079)was 15.8-fold higher than that of commercial P25(0.0005),The structure,morphology,chemical composition and optical properties of the as-prepared CN/NS-BT were characterized by various analytical methods,and possible photocatalytic enhancement mechanism was proposed.Overall,CN/NS-BT composites look promising as photocatalytic material for future environmental treatment. | MENG Zeshuol ZHOU Bo XU Jian LI Yaxin HU Xiaoying TIAN Hongwei | 2020 | Chemical Research in Chinese Universities2020，36，6： | 2 |
| 14 | Five Independent Cases of Human Infection with Avian Influenza H5N6—Sichuan Province,China,2021显示文摘Summary What is known about this topic?The emerging H5Ny lineages of the avian influenza virus(AIV)with genomic reassortments have posed a continuous threat to animals and human beings.Since the first case of avian influenza A(H5N6)virus infection in 2014,the World Health Organization has reported a total of 38 cases by August 6,2021. | Chongkun Xiao Jianan Xu Yu Lan Zhongping Huang Lijun Zhou Yaxin Guo Xiyan Li Lei Yang George F.Gao Dayan Wang William J.Liu Xingyu Zhou Huiping Yang | 2021 | China CDC weekly2021，3，36： | 2 |
| 15 | Solid-state cold spraying of FeCoCrNiMn high-entropy alloy:an insight into microstructure evolution and oxidation behavior at 700-900℃显示文摘About 3 mm thick five-element equimolar high-entropy alloy(HEA) FeCoCrNiMn was successfully deposited by solid-state cold spraying(CS).The high-temperature oxidation behavior of the CSed HEA was investigated at 700-900℃.Heat treatment was performed on the CSed HEA before oxidation to heal the incomplete interfaces between the deposited particles.Results show that the microstructure of the CSed HEA is characterized by grain refinement and abundant interparticle incomplete interfaces.Post-spray heat treatment promotes recrystallization and grain growth in the CSed HEA.After oxidation testing,the oxide scales are composed of multi-layers:a Mn_(2)O_(3)(or Mn_(3)O_(4)) outer layer,a Mn-Cr spinel intermediate layer and a Cr_(2)O_(3) inner layer.The CSed HEA exhibits higher parabolic rate constants and more favorable internal oxidation than the bulk HEAs that have similar compositions in the literature.Such a discrepancy becomes pronounced at higher temperatures.The grain refinement and numerous particle boundaries are responsible for such a distinctive performance of the CSed HEA. | Yaxin Xu Weny Li Longzhen Qu Xiawei Yang Bo Song Rocco Lupoi Shuo Yin | 2021 | Journal of Materials Science & Technology2021，，9： | 2 |
| 16 | Synthesis of thermoresponsive polystyrene-based comb-type grafted poly(N-isopropylacrylamide)显示文摘Narrowly distributed polystyrene-g-p(N-isopropylacrylamide) (PSt-g-PNIPAM) was prepared by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using the brominated polystyrene as macroinitiator and CuCl combined with hexamethyltriethylenetetramine as catalyst. Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of PSt-g-PNIPAM. The gel permeation chromatography (GPC) showed that the graft copoly- mer had a single distribution peak with molecular weight, Mn (g/mol) of 19815 g/mol (using polystyrene as the standard). Differential scanning calorimetry (DSC) revealed that due to both effects of hydro- phobic isopropyl groups and hydrogen bonds in the amide group, the glass transition temperature (Tg) of PSt-g-PNIPAM enhanced 16.0 ℃ compared to the Tg of the polystyrene. | XU YaXin LI HongTu ZHANG Kai ZHANG Bao AI Peng WANG JingYuan | 2007 | Science China Chemistry2007，50，5： | 2 |
| 17 | Whole-exome sequencing identified compound heterozygous variants in MMKS in a Chinese pedigree with Bardet-Biedl syndrome显示文摘Bardet-Biedl syndrome(BBS) is a genetically heterogeneous disorder characterized by retinal dystrophy, polydactyly, obesity,developmental delay, and renal defects. At least 21 candidate BBS-associated genes(BBS1-19, NPHP1, and IFT172) have previously been identified, and all of them play important roles in ciliary function. Here, we collected a BBS pedigree with four members and performed whole-exome sequencing on the proband. The variants were analyzed and evaluated to confirm their pathogenicity. We found compound heterozygous variants(c.1192C>T, p.Q398* and c.1175C>T, p.T392M) in MKKS in both the siblings, and these were likely to be pathogenic variants. We also found a missense variant(c.2029G>C, p.E677Q) in NPHP1 and a missense variant(c.2470C>T, p.R824C) in BBS9 in the proband only, which are variants of uncertain significance. The compound heterozygous variants were probably responsible for the BBS phenotype in this Chinese pedigree and the missense mutations in NPHP1 and BBS9 might contribute to the mutation load. | Zhan Qi Ying Shen Qian Fu Wei Li Wei Yang Wenshan Xu Ping Chu Yaxin Zhang Hui Wang | 2017 | Science China(Life Sciences)2017，60，7： | 2 |
| 18 | Post-mortem tissue proteomics reveals the pathogenesis of multi-organ injuries of COVID-19显示文摘Multi-organ injuries are a major complication of severe Coronavirus Disease 2019(COVID-19).However,its pathogenesis is barely understood.Herein;we profile host responses to fatal SARS-CoV-2 infection by performing quantitative proteomics of 19 post-mortem samples of 8 different organs or tissues,including lungs,liver,intestine,kidney;spleen,brain,heart and muscle,from 3 deceased COVID-19 victims during the first wave of the pandemic(Supplementary Fig.S1A and B,Tables SI-S3). | Yang Qiu Di Wu Wanshan Ning Jiqian Xu Ting Shu Muhan Huang Rong Chen Jiancheng Zhang Yang Han Qingyu Yang Ruiting Li Xiaobo Yang Yaxin Wang Xiaojing Zou Shangwen Pan Chaolin Huang Yu Xue You Shang Xi Zhou | 2021 | National Science Review2021，8，11： | 1 |
| 19 | Hybrid deep learning model for risk prediction of fracture in patients with diabetes and osteoporosis显示文摘The fracture risk of patients with diabetes is higher than those of patients without diabetes due to hyperglycemia,usage of diabetes drugs,changes in insulin levels,and excretion,and this risk begins as early as adolescence.Many factors including demographic data(such as age,height,weight,and gender),medical history(such as smoking,drinking,and menopause),and examination(such as bone mineral density,blood routine,and urine routine)may be related to bone metabolism in patients with diabetes.However,most of the existing methods are qualitative assessments and do not consider the interactions of the physiological factors of humans.In addition,the fracture risk of patients with diabetes and osteoporosis has not been further studied previously.In this paper,a hybrid model combining XGBoost with deep neural network is used to predict the fracture risk of patients with diabetes and osteoporosis,and investigate the effect of patients’physiological factors on fracture risk.A total of 147 raw input features are considered in our model.The presented model is compared with several benchmarks based on various metrics to prove its effectiveness.Moreover,the top 18 influencing factors of fracture risks of patients with diabetes are determined. | Yaxin Chen Tianyi Yang Xiaofeng Gao Ajing Xu | 2022 | Frontiers of Medicine2022，16，3： | 1 |
| 20 | Land cover classification in a mixed forest-grassland ecosystem using LResU-net and UAV imagery显示文摘Using an unmanned aerial vehicle (UAV) paired with image semantic segmentation to classify land cover within natural vegetation can promote the development of forest and grassland field. Semantic segmentation normally excels in medical and building classification, but its usefulness in mixed forest-grassland ecosystems in semi-arid to semi-humid climates is unknown. This study proposes a new semantic segmentation network of LResU-net in which residual convolution unit (RCU) and loop convolution unit (LCU) are added to the U-net framework to classify images of different land covers generated by UAV high resolution. The selected model enhanced classification accuracy by increasing gradient mapping via RCU and modifying the size of convolution layers via LCU as well as reducing convolution kernels. To achieve this objective, a group of orthophotos were taken at an altitude of 260 m for testing in a natural forest-grassland ecosystem of Keyouqianqi, Inner Mongolia, China, and compared the results with those of three other network models (U-net, ResU-net and LU-net). The results show that both the highest kappa coefficient (0.86) and the highest overall accuracy (93.7%) resulted from LResU-net, and the value of most land covers provided by the producer’s and user’s accuracy generated in LResU-net exceeded 0.85. The pixel-area ratio approach was used to calculate the real areas of 10 different land covers where grasslands were 67.3%. The analysis of the effect of RCU and LCU on the model training performance indicates that the time of each epoch was shortened from U-net (358 s) to LResU-net (282 s). In addition, in order to classify areas that are not distinguishable, unclassified areas were defined and their impact on classification. LResU-net generated significantly more accurate results than the other three models and was regarded as the most appropriate approach to classify land cover in mixed forest-grassland ecosystems. | Chong Zhang Li Zhang Bessie Y.J.Zhang Jingqian Sun Shikui Dong Xueyan Wang Yaxin Li Jian Xu Wenkai Chu Yanwei Dong Pei Wang | 2022 | Journal of Forestry Research2022，33，3： | 1 |
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