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Slippery hydrogel with desiccation-tolerant‘skin’for high-precision additive manufacturing

International Journal of Extreme Manufacturing 2024年第2期6卷 486-500页

作者： Desheng Liu pan Jiang Yue Hu yaozhong Lu Yixian Wang Jiayu Wu Danli Hu Tao Wu Xiaolong Wang State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000People’s Republic of China CAS Key Laboratory of Chemistry of Northwestern Plant Resources Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000People’s Republic of China Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai Yantai Zhongke Research Institute of Advanced Materials and Green Chemical EngineeringYantai 264006People’s Republic of China Key Laboratory of Materials-Oriented Chemical Engineering of Xinjiang Uygur Autonomous Region School of Chemistry and Chemical EngineeringShihezi UniversityShihezi 832003People’s Republic of China

Hydrogels inevitably undergo dehydration,structural collapse,and shrinkage deformation due to the uninterrupted evaporation in the atmosphere,thereby losing their flexibility,slipperiness,and manufacturing precision.Here,we propose a novel bioinspired strategy to construct a spontaneously formed‘skin’on the slippery hydrogels by incorporating biological stress metabolites trehalose into the hydrogel network,which can generate robust hydrogen bonding interactions to restrain water evaporation.The contents of trehalose in hydrogel matrix can also regulate the desiccation-tolerance,mechanical properties,and lubricating performance of slippery hydrogels in a wide range.Combining vat photopolymerization three-dimensional printing and trehalose-modified slippery hydrogels enables to achieve the structural hydrogels with high resolution,shape fidelity,and sophisticated architectures,instead of structural collapse and shrinkage deformation caused by dehydration.And thus,this proposed functional hydrogel adapts to manufacture large-scale hydrogels with sophisticated architectures in a long-term process.As a proof-of-concept demonstration,a high-precision and sophisticated slippery hydrogel vascular phantom was easily fabricated to imitate guidewire intervention.Additionally,the proposed protocol is universally applicable to diverse types of hydrogel systems.This strategy opens up a versatile methodology to fabricate dry-resistant slippery hydrogel for functional structures and devices,expanding their high-precision processing and broad applications in the atmosphere.

关键词： slippery hydrogel trehalose desiccation tolerance vat photopolymerization 3D printing hydrogen bonding

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Performance of different drought indices for agriculture drought in the North China Plain

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Journal of Arid Land 2018年第4期10卷 507-516页

作者： LIU Xianfeng ZHU Xiufang pan yaozhong BAI Jianjun LI Shuangshuang School of Geography and Tourism Shaanxi Normal University Institute of Remote Sensing Science and Engineering Faculty of Geographical Sciences Beijing Normal University

The Palmer drought severity index （PDSI）, standardized precipitation index （SPI）, and standardized precipitation evapotranspiration index （SPEI） are used worldwide for drought assessment and monitoring. However, substantial differences exist in the performance for agricultural drought among these indices and among regions. Here, we performed statistical assessments to compare the strengths of different drought indices for agricultural drought in the North China Plain. Small differences were detected in the comparative performances of SPI and SPEI that were smaller at the long-term scale than those at the short-term scale. The correlation between SPI/SPEI and PDSI considerably increased from 1- to 12-month lags, and a slight decreasing trend was exhibited during 12- and 24-month lags, indicating a 12-month scale in the PDSI, whereas the SPI was strongly correlated with the SPEI at 1- to 24-month lags. Interestingly, the correlation between the trend of temperature and the mean absolute error and its correlation coefficient both suggested stronger relationships between SPI and the SPEI in areas of rapid climate warming. In addition, the yield-drought correlations tended to be higher for the SPI and SPEI than that for the PDSI at the station scale, whereas small differences were detected between the SPI and SPEI in the performance on agricultural systems. However, large differences in the influence of drought conditions on the yields of winter wheat and summer maize were evident among various indices during the crop-growing season. Our findings suggested that multi-indices in drought monitoring are needed in order to acquire robust conclusions.

关键词： agriculture drought Palmer drought severity index standardized precipitation index standardize dprecipitation evapotranspiration index North China Plain

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SIMULATION OF MAXIMUM LIGHT USE EFFICIENCY FOR SOME TYPICAL VEGETATION TYPES IN CHINA

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Chinese Science Bulletin 2006年第4期51卷 457-463页

作者： ZHU Wenquan pan yaozhong HE Hao YU Deyong HU Haibo Key Laboratory of Environmental Change and Natural Disaster ofMinistry of Education College of Resources Science and TechnologyBeijing Normal University Beijing 100875 China Institute of Urban Meteorology China Meteorological Administration Beijing 100089 China

Maximum light use efficiency (εmax) is a key parameter for the estimation of net primary pro-ductivity (NPP) derived from remote sensing data. There are still many divergences about its value for each vegetation type. The εmax for some typical vegetation types in China is simulated using a modi-fied least squares function based on NOAA/AVHRR remote sensing data and field-observed NPP data. The vegetation classification accuracy is introduced to the process. The sensitivity analysis of εmax to vegetation classification accuracy is also conducted. The results show that the simulated values of εmax are greater than the value used in CASA model, and less than the values simulated with BIOME-BGC model. This is consistent with some other studies. The rela-tive error of εmax resulting from classification accuracy is ?5.5%―8.0%. This indicates that the simulated values of εmax are reliable and stable.

关键词：植物生理学植被类型最大日光利用效率遥感净初级生产力

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Spatiotemporal changes in vegetation coverage and its driving factors in the Three-River Headwaters Region during 2000-2011

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Journal of Geographical Sciences 2014年第2期24卷 288-302页

作者： LIU Xianfeng ZHANG Jinshui ZHU Xiufang pan yaozhong LIU Yanxu ZHANG Donghai LIN Zhihui State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing 100875 China College of Resources Science & Technology Beijing Normal University Beijing 100875 China College of Urban and Environmental Sciences Peking University Beijing 100871 China College of Tourism and Environment Shaanxi Normal University Xi'an 710062 China

The Three-River Headwaters Region （TRHR）, which is the source area of the Yangtze River, Yellow River, and Lancang River, is of key importance to the ecological secu- rity of China. Because of climate changes and human activities, ecological degradation oc- curred in this region. Therefore, ＂The nature reserve of Three-River Sou,＇ce Regions＂ was established, and ＂The project of ecological protection and construction for the Three-River Headwaters Nature Reserve＂ was implemented by the Chinese government. This study, based on MODIS-NDVI and climate data, aims to analyze the spatiotemporal changes in vegetation coverage and its driving factors in the TRHR between 2000 and 2011, from three dimensions. Linear regression, Hurst index analysis, and partial correlation analysis were employed. The results showed the following：（1） In the past 12 years （2000-2011）, the NDVI of the study area increased, with a linear tendency being 1.2%/10a, of which the Yangtze and Yellow River source regions presented an increasing trend, while the Lancang River source region showed a decreasing trend. （2） Vegetation coverage presented an obvious spatial difference in the TRHR, and the NDVI frequency was featured by a bimodal structure. （3） The area with improved vegetation coverage was larger than the degraded area, being 64.06% and 35.94%, respectively during the study period, and presented an increasing trend in the north and a decreasing trend in the south. （4） The reverse characteristics of vegetation cov- erage change are significant. In the future, degradation trends will be mainly found in the Yangtze River Basin and to the north of the Yellow River, while areas with improving trends are mainly distributed in the Lancang River Basin. （5） The response of vegetation coverage to precipitation and potential evapotranspiration has a time lag, while there is no such lag in the case of temperature. （6） The increased vegetation coverage is mainly attributed to the warm-wet climate change and the implementation of the ecological protectio

关键词： vegetation coverage spatiotemporal change future trend influence factors Three-River HeadwatersRegion

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A novel spectral index for mapping blue colour-coated steel roofs(BCCSRs)in urban areas using Sentinel-2 data

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International Journal of Digital Earth 2023年第1期16卷 2862-2884页

作者： Chuanwu Zhao yaozhong pan State Key Laboratory of Remote Sensing Faculty of Geographical ScienceBeijing Normal UniversityBeijingPeople’s Republic of China Key Laboratory of Environmental Change and Natural Disasters of Chinese Ministry of Education Beijing Normal UniversityBeijingPeople’s Republic of China Academy of Plateau Science and Sustainability Qinghai Normal UniversityXiningPeople’s Republic of China Beijing Engineering Research Center for Global Land Remote Sensing Products Faculty of Geographical ScienceBeijing Normal UniversityBeijingPeople’s Republic of China

Blue colour-coated steel roofs(BCCSRs)offer a lightweight and economical option to concrete and other cladding in buildings,but they are also controversial for altering the surface energy budget and water cycle.Obtaining spatial information about BCCSRs is crucial for exploring the environmental impacts of man-made landscapes.However,existing methods are not always effective due to the variety of BCCSR types and background conditions.To overcome these limitations,we proposed a new index(called BCCSI)based on Sentinel-2 multispectral images to map the commonly used BCCSRs.Five typical study areas were chosen worldwide to develop and validate the BCcSl.Based on spectral analysis,we constructed the BCCSl using the blue,red,green,and shortwave infrared 2(SWIR2)bands to highlight the BCCSR while suppressing the background condition.Compared with five existing indices,the BCCSl was effective in the visual evaluation,separability analysis and BCCSR mapping.Moreover,the BCCSI achieved similar accuracy to the supervised classifier while avoiding the time-consuming and laborious effort of sample collection.Furthermore,the BCCSl showed its applicability in medium-resolution satellite data,such as Landsat-8 imagery.Thus,the proposed BCCSI provides a viable scheme for global BCCSR mapping and analysis.

关键词： Blue colour-coated steel roof Large-scale mapping Surface energy budget Sentinel 2 Landsat 8

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Restoring urbanization process in China in the 1990s by using non-radiance-calibrated DMSP/OLS nighttime light imagery and statistical data

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Chinese Science Bulletin 2006年第13期51卷 1614-1620页

作者： HE Chunyang SHI Peijun LI dinggang CHEN din pan yaozhong LI ding ZHUO Li Ichinose Toshiaki Key Laboratory of Environmental Change and Natural Disaster Min istry of Education of China College of Resources Science & Tech nology Beijing Normal University Beijing 100875 China Japan National Institute of Environmental Studies 16-20nogawa Tsukuba 305-8506 Japan

Since current administrative unit-based urban land area statistical data in China lack enough spatial information, the urbanization process re- search at large scale cannot be effectively supported. Based on the current administrative unit-based urban land area statistical data in China, a new approach to quickly and cheaply derive urban land information from the non-radiance-calibrated Defense Meteoro- logical Satellite Program/ Operational Linescan Sys- tem (DMSP/OLS) nighttime light imagery is pre- sented in this paper. With the new approach, the ur- ban pattern information in China in 1992, 1996 and 1998 was derived with the urbanization processes in China in the 1990s restored by using the non-ra- diance-calibrated DMSP/OLS nighttime imagery. The accuracy assessment based on the statistical data showed that the relative error between the derived total urban land area and the statistical data at na- tional scale was less than 2% in 1992, and less than 1% in 1996 and 1998, and the maximum relative er- ror at province scale do not exceed 10% with most of the provinces less than 3%. In addition, the urban patterns derived from the high-resolution Landsat TM imagery were compared with those from the DMSP/ OLS data. The results showed that the urban pattern characteristics derived from DMSP/OLS were basi-cally coincident with those from TM imagery with the total accuracy of about 80%. Thus it can be seen that our restored urbanization process in China in the 1990s by using the non-radiance DMSP/OLS night- time imagery can be accepted and can represent the actual urban development in China at that time on the whole.

关键词：城市化中国 DMSP/OLS 统计数据

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Understanding cultivated land dynamics and its driving forces in northern China during 1983-2001

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Journal of Geographical Sciences 2005年第4期15卷 387-395页

作者： HE Chunyang LI Jinggang WANG Yuanyuan SHI Peijun CHEN Jin pan yaozhong Key Laboratory of Environmental Change and Natural Disaster Ministry of Education of China Beijing Normal University College of Resources Science ＆ Technology Beijing NormalUniversity Beijing 100875 China Institute of Remote Sensing Applications CAS Beijing 100101 China

Based on the long-term serial NOAA/NDVI dataset during 1983-1999 and SPOT/VGT dataset in 2001, the land use/cover change information in the 13 provinces of northern China was extracted based on the analysis of the cultivated landscape characteristics at first, then the effects of human activities on cultivated land process were explored by GIS and the driving forces of cultivated land change were investigated. The conclusions can be drawn as follows：（1） The constant increase of weak ecological function land as desert and cultivated land and the decrease of the ecological function land of forest and shrub were the main characteristics of the land use/cover change in the 13 provinces from 1983 to 1999, which showed the effects on the ecological adjustment fimction. However, such situations were changed to some extent in the 2000s because of the eco-construction policy of the government. （2） From 1983 to 2001, the Barycenter of cultivated land tended to move from northeast to southwest with the topography and transportation situations being the main influences on the cultivated land distribution. It is found that the cultivated land use intensity decreased noticably with the increase of distance from the main communication arteries. （3） The improvement of the people＇s living standard is closely related with the cultivated land change. The structural adjustment in the agricultural land caused by economic development and the improvement of the people＇s living standard ig an important factor affecting the cultivated land change in northern China from 1983 to 2001

关键词： cultivated land change spatial process driving forces northern China

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The urbanization process of Bohai Rim in the 1990s by using DMSP/OLS data

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Journal of Geographical Sciences 2006年第2期16卷 174-182页

作者： HE Chunyang LI Jinggang CHEN Jing SHI Peijun CHEN Jin pan yaozhong LI Jing ZHUO Li Ichinose Toshiaki Key Laboratory of Environmental Change and Natural Disaster Ministry of Education of ChinaBeijing Normal University College of Resources Science ＆ Technology Beijing Normal UniversityBeijing 100875 China Institute of Remote Sensing Applications CAS. Beijing 100101 China Japan National Institute of Environmental Studies 16-2 Onogawa Tsukuba 305-8506 Japan

This paper firstly derived urban information from Defense Meteorological Satellite Program/Operational Linescan System （DMSP/OLS） data in 1992, 1996 and 1998 with the support of statistical data, and then developed three basic urban models of polygon-urbanization, line-urbanization and point-urbanization in urban agglomerations from viewpoint of spatial analysis. The conclusions are as follows：（1） Urban patch numbers in the Bohai Rim increased from 1659 to 2053 with an annual average increase number of about 66. Meanwhile, the small urban patches accounted for a larger proportion in the region and the patch density increased fast. In addition, the urban barycenter of the region showed a moving trend toward northwest from 1992 to 1998. Urbanization in the Bohai Rim in the 1990s is fast and obvious. （2） Urbanization in the Bohai Rim can be reflected by three basic processes, i.e., the polygon-urbanization around the big cities, the line-urbanization around the transportation lines and the point-urbanization emerging in large areas. Of them, the polygon-urbanization has been in dominance. It is obviously within an effective range of 3-4 km surrounding the urban patches. The line-urbanization and point-urbanization in the region was relatively small, both of which showed an obvious increasing trend.

关键词： DMSP/OLS urbanization agglomeration urbanization spatial mode process Bohal Rim

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基于冷暖季放牧区划分的玉树州草畜平衡估算及变化分析

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草业科学 2024年第4期41卷 1007-1019页

作者：夏兴生马国秀车红岩潘耀忠黄永生李宏达青海师范大学高原科学与可持续发展研究院青海西宁810016 青海师范大学地理科学学院青海西宁810016 北京师范大学地理科学学部遥感科学国家重点实验室北京100875 青海省草原总站青海西宁810008

玉树州作为三江源高寒生态屏障区以牧为主农牧业结合发展的核心地区,草畜平衡不仅关系生态屏障安全,也对实现科学的畜牧业经济管理具有重要的指导意义。因此,本研究以探究高寒生态屏障区天然草地的草畜平衡变化为目的,选择玉树州为研究... 详细信息

玉树州作为三江源高寒生态屏障区以牧为主农牧业结合发展的核心地区,草畜平衡不仅关系生态屏障安全,也对实现科学的畜牧业经济管理具有重要的指导意义。因此,本研究以探究高寒生态屏障区天然草地的草畜平衡变化为目的,选择玉树州为研究区,利用2014-2019年MOD13A1 NDVI产品数据和MOD17A3H NPP产品数据、统计数据、植被类型数据,在划分县域冷暖两季放牧区的基础上,以“木桶效应”确定了各县(市)天然草地的合理载畜量并对其草畜平衡进行了评估。结果表明:1)按照理论上的自然轮牧规律,参考固定面积比例和年内NDVI的时空分布规律划分的玉树州各县(市)冷季放牧区分布于较温暖的沟谷地区,暖季放牧区处于高寒区域,且冷季放牧区产草量大于暖季放牧区。2)年际间冷暖季放牧区干草产量均呈波动增长趋势,年均增长率均在3.00%以上且暖季放牧区年产草量增长率大于冷季放牧区。3)2014-2019年玉树州整体的草畜平衡状态由临界超载和超载波动转为平衡,但各县(市)草畜平衡状态存在差异,推测可能是因为自然保护区和国家公园生态工程支持的空间范围差异引起的。本研究对进一步修订三江源自然保护区和国家公园建设方案,实施高寒生态屏障区生态和畜牧业经济的良性发展策略具有一定的参考价值。

关键词：遥感轮牧木桶效应高寒草地载畜量生态屏障区青藏高原

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Using a simulation analysis to evaluate the impact of crop mapping error on crop area estimation from stratified sampling

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International Journal of Digital Earth 2019年第9期12卷 1046-1066页

作者： Peijun Sun Russell G.Congalton yaozhong pan State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of SciencesBeijingPeople’s Republic of China Institute of Remote Sensing and Engineering Faculty of Geographical ScienceBeijing Normal UniversityBeijingPeople’s Republic of China Department of Natural Resources&the Environment University of New HampshireDurhamNHUSA

To analyze the efficiency of area estimations(i.***.estimation accuracy and variation of estimation)impacted by crop mapping error,we simulated error at eight levels for thematic maps using a stratified sampling estimation methodology.The results show that the estimation efficiency is influenced by the combination of the sample size and the error level.Evaluating the trade-offs between sample size and error level showed that reducing the crop mapping error level provides the most benefit(i.***.higher estimation efficiency).Further,sampling performance differed based on the heterogeneity of the crop area.The results demonstrated that the influence of increasing the error level on estimation efficiency is more detrimental in heterogeneous areas than in homogeneous ones.Therefore,to obtain higher estimation efficiency,a larger sample size and lower error level or both are needed,especially in heterogeneous areas.We suggest that existing land-cover maps should first be used to determine the heterogeneity of the area.The appropriate sample size for these areas then can be determined according to all three factors:heterogeneity,expected estimation efficiency,and sampling budget.Overall,extending our understanding of the impacts of crop mapping error is necessary for decision making to improve our ability to effectively estimate crop area.

关键词： Crop mapping error area estimation estimation efficiency landscape heterogeneity stratified sampling

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