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Optimization of desert lake information extraction from remote sensing images using cellular automata

International Journal of Coal Science & Technology 2023年第3期10卷 214-224页

作者： Qiuji chen Yanan cao College of Geomatics Xi'an University of Science and TechnologyXi'an 710054China

Desert lakes are important wetland resources in the blown-sand area of western China and play a significant role in maintain-ing the regional ecological environment.However,large-scale coal mining in recent years has considerably impacted the deposition condition of several lakes.Rapid and accurate extraction of lake information based on satellite images is crucial for developing protective measures against desertification.However,the spatial resolution of these images often leads to mixed pixels near water boundaries,affecting extraction precision.Traditional pixel unmixing methods mainly obtain water coverage information in a mixed pixel,making it difficult to accurately describe the spatial distribution.In this paper,the cellular automata(CA)model was adopted in order to realize lake information extraction at a sub-pixel level.A mining area in Shenmu City,Shaanxi Province,China is selected as the research region,using the image of Sentinel-2 as the data source and the high spatial resolution UAV image as the reference.First,water coverage of mixed pixels in the Sentinel-2 image was calculated with the dimidiate pixel model and the fully constrained least squares(FCLS)method.Second,the mixed pixels were subdivided to form the cellular space at a sub-pixel level and the transition rules are constructed based on the water coverage information and spatial correlation.Lastly,the process was implemented using Python and IDL,with the ArcGIS and ENVI software being used for validation.The experiments show that the CA model can improve the sub-pixel positioning accuracy for lake bodies in mixed pixel image and improve classification accuracy.The FCLS-CA model has a higher accuracy and is able to identify most water bodies in the study area,and is therefore suitable for desert lake monitor-ing in mining areas.

关键词： Blown-sand mining area Desert lake Remote sensing Mixed pixel Cellular automata

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Bioavailability of nanomaterials:bridging the gap between nanostructures and their bioactivity

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National Science Review 2022年第10期9卷 59-62页

作者： Mingjing cao Chunying chen CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology of China University of Chinese Academy of Sciences The GBA National Institute for Nanotechnology Innovation

Nanomaterials (NMs) have enormous potential as nanomedicines for diagnosing and fighting various diseases.Researchers make every endeavor to design diverse nanomedicines with novel nanostructures and smart payloads.Buthow stable are nanomedicines before and after exerting their functions at target sites?What can we do to maximizethe efficiency of nanomedicines?These questions have concerned researchers over the past two decades.The in vivo metabolic processes of nanomaterials are a key factor in understanding the safety and efficacy (end point)of nanomedicines.Clarification of these processes may bridge the gap between the cradle (structure design)and end point (efficacy and/or safety) of nanomedicines.Four possible metabolic phenomena have been revealed so far for NMs [1,2]:their elimination through renal and hepatobiliary systems,their interception in the mononuclear phagocyte system (MPS),their biodegradation and utilization in the liver and,finally,their excretion from the body after a gradual breakdown.

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Design and numerical analysis of serpentine microchannel integrated with inner-wall ridges for enhanced droplet mixing

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Science China(Technological Sciences) 2023年第2期66卷 560-573页

作者： cao Xiang chen YongPing Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Environmental Science and EngineeringSuzhou University of Science and TechnologySuzhou 215009China

A numerical model is developed for three-dimensional droplet mixing in serpentine microchannels with inner-wall ridges(referred to as SMR microchannels).The underlying mechanisms of mixing in SMR microchannels are revealed,and the effects of the ridge width and ridge number on mixing inside droplets of different sizes are clarified.The results indicate that SMR microchannels are capable of enhancing the mixing efficiency by 3.6%–12.5%compared with that in smooth serpentine microchannels,particularly when the droplet length is larger than the microchannel width and the width ratio of the ridge to the microchannel is 0.25–1.The above mixing enhancement is determined by two main factors:the combined effects of the vortex pair and reverse flow,and non-horizontal vortices.Moreover,when the width ratio is 1,there is a maximum 16.0%increase in mixing efficiency for small droplets with a length equal to the microchannel width.However,for small droplets,mixing in an SMR microchannel is worse than in a smooth serpentine microchannel when the width ratio is less than 0.75.With increasing the ridge number,when the width ratio is 0.25,the mixing efficiency is reduced for small droplets but increased for larger droplets.

关键词： droplet mixing serpentine microchannel ridge microfluidics

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From De-collectivization to Re-collectivization: New Transformation Trend in Agriculture Production in Taicang City of the Eastern China from the Perspective of ‘Governmentality’

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Chinese Geographical Science 2023年第3期33卷 531-548页

作者： chen cheng GAO Jinlong cao Hui chen Jianglong chen Feiyu Key Laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and LimnologyNanjing 210008China Jiangsu Collaborative Innovation Center of Regional Modern Agriculture&Environmental Protection Huaiyin Normal UniversityHuaian 223001China Nanjing College University of Chinese Academy of ScienceNanjing 211135China

The continuous development of agricultural technologies and produces trade and updated state reforms strongly shape the dominant organizing styles of local agriculture production.Since the end of the 1970s,rural China has witnessed a drastic agriculture transformation featured by de-collectivization,and recently in Taicang,a developed city in the eastern China,a kind of new cooperative farms have replaced the smallholders by pooling households’contracted farmland,signaling a new shift tendency towards agriculture recollectivization that is distinctive compared to other countries.Given the state governance’s leadership in promoting this latest transformation,drawing on the theoretical concept of‘governmentality’that is powerful in understanding how to govern the society to meet certain objectives,this paper examines the accurate processes of agriculture re-collectivization in Taicang City based on the methods of semi-structured interview and participant observation.Our research shows that the China’s tax-sharing and relevant reforms in the 1990s framed a new governance structure in line with the new mode of‘governmentality’closely linked to‘advanced liberalism’,creating the responsibility shift from central to local governments and a set of evaluation technologies,and guiding various actors to engage in the agriculture re-collectivization practice in Taicang.Importantly,the considerable subsidies and the impressive extension services in terms of farming personnel training and agricultural techniques diffusion underpin the normal running of cooperative farms and contribute to the local implementation of national strategy of agriculture modernization.We argue that the combination of distinctive institutional arrangement of rural land owned by village collectives in China and the burgeoning local economy allows the developed areas to re-collectivizing the agriculture production for ensuring grain self-sufficiency rather than capturing more share in global agriculture products trade,and that the cooperative farms in o

关键词： Eastern Transformation collective

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Design and friction loss study of full-ocean depth oil-filled direct current motor

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第8期23卷 587-598页

作者： Hao WANG chen Cao Jin GUO Wei WANG Peng ZHOU Jia-wang chen Ocean College Zhejiang UniversityZhoushan 316000China

In this study,we designed an oil-filled motor that can be used at full-ocean depths,and investigated the friction losses caused by the rotating seal and the properties of the oil.The direct current(DC)motor is encapsulated in an aluminum alloy housing.A rubber diaphragm is used to balance the internal and external pressures so that the motor can work on the seabed without pressure difference.To study the resistance caused by the rotating seal,a numerical model of the Glyd ring and the rotating shaft was established.Results from a rotational torque test agreed with those from numerical analysis.The kinematic viscosity of four oils was measured at 1-25℃.Oil bath experiments in an incubator showed that the resistance from oil is highly correlated with its dynamic viscosity.Dimethicone appears to be very suitable as an insulating oil for these motors.The working characteristics of the motor were tested in a high-pressure chamber.The results showed that the motor needs to overcome higher oil resistance under higher pressure.A prototype of a pressure-adaptive motor was designed and applied successfully in the hadal zone at a water depth of more than 10000 m.

关键词： Oil-filled motor Full-ocean depth Rotating seals Friction loss Viscous power Sea trial

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Existence for V T-harmonic maps from compact manifolds with boundary

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Science China Mathematics 2022年第11期65卷 2371-2378页

作者： Xiangzhi cao Qun chen School of Information Engineering Nanjing Xiaozhuang UniversityNanjing 211171China School of Mathematics and Statistics Wuhan UniversityWuhan 430072China

We consider a kind of generalized harmonic maps,namely,the V T-harmonic maps.We prove an existence theorem for the Dirichlet problem of V T-harmonic maps from compact manifolds with boundary.

关键词： Dirichlet problem existence harmonic map

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A high frequency vibration compensation approach for ultrahigh resolution SAR imaging based on sinusoidal frequency modulation Fourier-Bessel transform

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Journal of Systems Engineering and Electronics 2023年第4期34卷 894-905页

作者： chen Siyu WANG Yong cao Rui School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China

Ultrahigh resolution synthetic aperture radar(SAR)imaging for ship targets is significant in SAR imaging,but it suffers from high frequency vibration of the platform,which will induce defocus into SAR imaging results.In this paper,a novel compensation method based on the sinusoidal frequency modulation Fourier-Bessel transform(SFMFBT)is proposed,it can estimate the vibration errors,and the phase shift ambiguity can be avoided via extracting the time frequency ridge consequently.By constructing the corresponding compensation function and combined with the inverse SAR(ISAR)technique,well-focused imaging results can be obtained.The simulation imaging results of ship targets demonstrate the validity of the proposed approach.

关键词： synthetic aperture radar(SAR) high frequency vibration compensation sinusoidal frequency modulation FourierBessel transform(SFMFBT)

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Analyses of the Duration and Dynamics of the COVID-19 Epidemic in 11 Severely Affected Countries

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Biomedical and Environmental Sciences 2021年第9期34卷 739-742页

作者： chen Cao SHI Qi DONG Xiao Ping State Key Laboratory for Infectious Disease Prevention and Control NHC Key Laboratory of Medical Virology and Viral DiseasesCollaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases(Zhejiang University)National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and PreventionBeijing 102206China Chinese Center for Disease Control and Prevention-Wuhan Institute of Virology Chinese Academy of Sciences Joint Research Center for Emerging Infectious Diseases and BiosafetyCenter for Biosafety Mega-ScienceChinese Academy of SciencesWuhan 430071HubeiChina Center for Global Public Health Chinese Center for Disease Control and PreventionBeijing 102206China China Academy of Chinese Medical Sciences Beijing 100700China

The COVID-19 pandemic has affected 220 countries,areas,and territories worldwide,with more than 65 million confirmed cases and 1.5 million deaths[1].By the beginning of May,2020,only a few countries,such as China,South Korea,Australia,and New Zealand,seemed to be close to the epidemic’s late stage with a few daily reported new cases[1].

关键词： fir COV milli

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Catalytic asymmetric synthesis of sulfur-containing atropisomers by C-S bond formations

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Science China Chemistry 2023年第12期66卷 3331-3346页

作者： Ren-Fei cao Zhi-Min chen School of Chemistry and Chemical Engineering Shanghai Key Laboratory for Molecular Engineering of Chiral DrugsShanghai Jiao Tong UniversityShanghai 200240China

Chiral organosulfur compounds are not only widely distributed in bioactive natural products and pharmaceuticals,but also play a significant role in chiral ligands/catalysts.Throughout the history of synthetic organic chemistry,chemists have been absorbed in the construction of centrally chiral organosulfur compounds.Nevertheless,there are relatively few reports on installing sulfur functional groups into axially chiral compounds.Atropisomerism is one of the fundamental phenomena in nature,which ubiquitously exists in natural products.After more than a century of development,atropisomers have been designed and extensively applied to pharmaceuticals,functional materials and chiral ligands/catalysts.Due to the importance of chiral sulfurcontaining atropisomers,there is an increasing demand for enantioselective synthesis of them.Recently,a diversity of approaches by C-S bond formations have been established for the construction of enantioenriched sulfur-containing atropisomers,however,there is no comprehensive review to summarize this great progress.In this mini-review,we summarize recent progress in catalytic asymmetric synthesis of sulfur-containing atropisomers by C-S bond formations,which includes sulfur nucleophilic reactions,sulfur electrophilic reactions and sulfur radical reactions.Furthermore,the reaction mechanisms are also discussed.We hope that this mini-review will enable more researchers to further explore this field.

关键词： atropisomers asymmetric catalysis C-S bond formations chiral organosulfur compounds

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Aqueous Room-Temperature Phosphorescence from Assembled Phosphors for Analytical Detection

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Chinese Journal of Chemistry 2023年第8期41卷 979-990页

作者： Peisheng cao Qian chen Peng Wu College of Chemistry Sichuan UniversityChengduSichuan610064 China Analytical&Testing Center State Key Laboratory of Hydraulics and Mountain River EngineeringSichuan UniversityChengduSichuan610064 China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiangHenan453007 China

Comprehensive Summary Room-temperature phosphorescence(RTP)has gained much attention in organic light-emitting diodes(OLEDs),anti-counterfeiting,encryption and bioimaging.However,efficient RTP is typically difficult due to the spin-forbidden transition nature and susceptibility to environment quenching.In aqueous phase,such quenching is much more pronounced,leading to the collection of aqueous RTP even more challenging.Assembly systems(either organic or inorganic),provide an excellent microenvironment for accommodating of phosphors in aqueous phase,due to the excluding of typical phosphorescence quenchers(H2O and O2)and rigidification of phosphorescent molecules for inhibition of non-radiative transitions(molecular motions).Herein,we summarized the recent progress in harvesting RTP from aqueous systems via various assembling strategies,including small molecules,supramolecular inclusion,and inorganic assembly.More specifically,the analytical explorations of these systems were discussed,from the perspective of the relationship between analytes and phosphorescence.Last,the further developments of aqueous RTP analysis were also prospected.

关键词： Room-temperaturephosphorescence Luminescence Aqueous Assembly Analytical detection

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