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Causes of maize density loss in farmers’ fields in Northeast China

Journal of Integrative Agriculture 2019年第8期18卷 1680-1689页

作者： ZHAO Ying-jie xing sen ZHANG Qing-song ZHANG Fu-suo MA Wen-qi Key Laboratory of Plant-Soil Interactions Ministry of Education Beijing 100193 P.R.China College of Resources and Environmental Sciences China Agricultural University Beijing 100193 P.R.China College of Resources and Environmental Science Hebei Agricultural University Baoding 071001 P.R.China

Increasing plant density is an effective and important way to reduce maize yield gaps in Northeast China. However, the fact is that a significant plant density gap exists between optimum plant density and actual plant density in farmers’ fields.To quantify the density gap between planned planting density and final harvest plant density(HPD), we studied 60 farmers’ fields on three types of soil for three crop seasons from 2015 to 2017 by measuring their plant-plant distance, actual seedlings density(ASD), final HPD and yield. We also explored the potential causes of density loss by digging the places where the seedlings were missing for two consecutive years in 2016–2017. Results show that the three-year average HPD in farmers’ fields was 59 699 plants ha^–1, which was significantly lower than the planned density, including both the machine setting density(MSD;67 962 plants ha^–1) and theoretical plant density(TPD;67 467 plants ha^–1). No significant difference was found in HPD between years and soil types. However, for MSD and TPD, the average value in 2015 was significantly higher than that in 2016 and 2017. No significant difference between soil types was observed. Furthermore,the results from 2016 till 2017 indicated that a lack of seeds in the soil, a failure to germinate due to low-quality seeds,and a lack of seedlings breaking out of the soil due to environmental problems explained approximately 60.88, 10.33 and 28.80% of density loss, respectively. According to our survey, 63% of farmers did not know their own TPD and HPD, and 54% of farmers did not know the density loss. Therefore, we argue that farmers’ limited knowledge of density and density loss is an urgent problem that needs to be solved in maize production. These observations will be useful for determining best management practices for maize production and for providing helpful suggestions for machine improvement.

关键词： plant density maize production density loss density gap farmers’ fields

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创新思维训练的案例化教学模式及其实践

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中国质量 2024年第1期 118-122页

作者：李兴森王龙浩张浩澜李绍英浙大宁波理工学院广东工业大学

创新思维能力的培养对工程教育具有重要的意义。本研究从创新能力不足的主要原因是缺乏有效的创新方法入手，将可拓学理论引入工程创新思维训练，通过经典故事的解读与大学生日常生活难题的流程化求解，形成一套案例化、形式化、流程化... 详细信息

创新思维能力的培养对工程教育具有重要的意义。本研究从创新能力不足的主要原因是缺乏有效的创新方法入手，将可拓学理论引入工程创新思维训练，通过经典故事的解读与大学生日常生活难题的流程化求解，形成一套案例化、形式化、流程化提升创新思维的可拓模式。本研究通过对比实验验证了该方法的应用效果。通过案例的可拓学分析等方法训练创新思维的模式对其他课程的教学创新也具有一定的参考作用。

关键词：创新思维案例化教学可拓学工程教育

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Rapid prediction models for 3D geometry of landslide dam considering the damming process

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Journal of Mountain Science 2023年第4期20卷 928-942页

作者： WU Hao NIAN Ting-kai SHAN Zhi-gang LI Dong-yang GUO xing-sen JIANG Xian-gang Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu610041China Power China Huadong Engineering Corporation Limited Hangzhou310014China School of Civil Engineering Dalian University of TechnologyDalian116024China Department of Civil EnvironmentalGeomatic EngineeringUniversity College LondonLondonWC1E 6BTUK College of Civil Engineering Sichuan Agricultural UniversityChengdu610041China

The geometry of a landslide dam plays a critical role in its stability and failure mode,and is influenced by the damming process.However,there is a lack of understanding of the factors that affect the 3D geometry of a landslide dam.To address this gap,we conducted a study using the smoothed particle hydrodynamics numerical method to investigate the evolution of landslide dams.Our study included 17 numerical simulations to examine the effects of several factors on the geometry of landslide dams,including valley inclination,sliding angle,landslide velocity,and landslide mass repose angle.Based on this,three rapid prediction models were established for calculating the maximum height,the minimum height,and the maximum width of a landslide dam.The results show that the downstream width of a landslide dam remarkably increases with the valley inclination.The position of the maximum dam height along the valley direction is independent of external factors and is always located in the middle of the landslide width area.In contrast,that position of the maximum dam height across the valley direction is significantly influenced by the sliding angle and landslide velocity.To validate our models,we applied them to three typical landslide dams and found that the calculated values of the landslide dam geometry were in good agreement with the actual values.The findings of the current study provide a better understanding of the evolution and geometry of landslide dams,giving crucial guidance for the prediction and early warning of landslide dam disasters.

关键词： Landslide dam Runout distance SPH numerical simulations Rapid prediction models

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Conceptual design of a 714-MHz RFQ for compact proton injectors and development of a new tuning algorithm on its aluminium prototype

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Nuclear Science and Techniques 2024年第1期35卷 45-58页

作者： Yi-xing Lu Wen-Cheng Fang Yu-sen Guo Zhen-Tang Zhao Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800China University of Chinese Academy of Sciences Beijing 101408China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201204China Shanghai Key Laboratory of Cryogenics&Superconducting RF Technology Shanghai 201800China ShanghaiTech University Shanghai 201210China

Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.

关键词： Compact proton injector RFQ IH-DTL High gradient Tuning

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Bimodal growth of Fe islands on graphene

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Chinese Physics B 2024年第6期33卷 553-557页

作者：顾翊晟俞俏滟刘荡孙蓟策席瑞骏陈星森薛莎莎章毅杜宪宁旭辉杨浩管丹丹刘晓雪刘亮李耀义王世勇刘灿华郑浩贾金锋 Key Laboratory of Artificial Structures and Quantum Control TD Lee InstituteShenyang National Laboratory for Materials ScienceSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area(Guangdong) Shenzhen 518045China

Magnetic metals deposited on graphene hold the key to applications in spintronics. Here, we present the results of Fe islands grown on graphene/Si C(0001) by molecular beam epitaxy, which are investigated by scanning tunneling microscopy. The two types of islands distinguished by flat or round tops are revealed, indicating bimodal growth of Fe. The atomic structures on the top surfaces of flat islands are also clearly resolved. Our results may improve the understanding of the mechanisms of metals deposited on graphene and pave the way for future spintronic applications of Fe/graphene systems.

关键词： graphene magnetism molecular beam epitaxy scanning tunneling microscopy

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基于U-Net网络的鸟群图像分割研究

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信息技术 2024年第1期48卷 122-127页

作者：杨昌其王馨悦张晓磊刘一海赵星森中国民用航空飞行学院空中交通管理学院四川广汉618307 汕头大学广东汕头515063

当前在通用航空活动中对于鸟群活动情况的了解还是依靠飞行员对环境的观察,并且国内外驱鸟方式并不适合大范围推广使用,着眼于以上问题,利用基于深度学习的图像分割方法来解决该问题,将U-Net图像分割策略引入航空图像分析中,通过深度卷... 详细信息

当前在通用航空活动中对于鸟群活动情况的了解还是依靠飞行员对环境的观察,并且国内外驱鸟方式并不适合大范围推广使用,着眼于以上问题,利用基于深度学习的图像分割方法来解决该问题,将U-Net图像分割策略引入航空图像分析中,通过深度卷积神经网络对鸟群活动图像进行处理;针对图像背景复杂、目标分布不均匀且大小不定等特点,提出优化U-Net网络,以更好地保存和利用图像信息。实验证明该优化网络图像分割效果优于现有方法。

关键词：深度学习网络注意力机制鸟群活动图像分割航空安全

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Autism spectrum disorders: autistic phenotypes and complicated mechanisms

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World Journal of Pediatrics 2019年第1期15卷 17-25页

作者： Xi-Cheng Zhang Li-Qi Shu xing-sen Zhao Xue-Kun Li Children's Hospital Zhejiang University School of MedicineHangzhou 310003China Institute of Translational Medicine School of MedicineZhejiang UniversityHangzhou 310029China School of Medicine and Health Sciences George Washington UniversityWashingtonDCUSA

Background Autism spectrum disorder (ASD),a pervasive developmental neurological disorder,is characterized by impairments in social interaction and communication,and stereotyped,repetitive patterns of interests or behaviors.The mechanism of ASDs is complex,and genetic components and epigenetic modifications play important roles.In this review,we summarized the recent progresses of ASDs focusing on the genetic and epigenetic mechanisms.We also briefly discussed current animal models of ASD and the application of high-throughput sequencing technologies in studying ASD.Data sources Original research articles and literature reviews published in PubMed-indexed journals.Results Individuals with ASDs exhibit a set of phenotypes including neurological alteration.Genetic components including gene mutation,copy-number variations,and epigenetic modifications play important and diverse roles in ASDs.The establishment of animal models and development of new-generation sequencing technologies have contributed to reveal the complicated mechanisms underlying autistic phenotypes.Conclusions Dramatic progress has been made for understanding the roles of genetic and epigenetic components in ASD.Future basic and translational studies should be carried out towards those candidate therapeutic targets.

关键词： Autism spectrum disorders Genetics Epigenetics CNV Next-generation sequencing

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Landscape ecological risk assessment and its driving factors in the Weihe River basin,China

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Journal of Arid Land 2024年第5期16卷 603-614页

作者： CHANG sen WEI Yaqi DAI Zhenzhong XU Wen WANG xing DUAN Jiajia ZOU Liang ZHAO Guorong REN Xiaoying FENG Yongzhong College of Agronomy Northwest A&F UniversityYangling 712100China

Weihe River basin is of great significance to analyze the changes of land use pattern and landscape ecological risk and to improve the ecological basis of regional development.Based on land use data of the Weihe River basin in 2000,2010,and 2020,with the support of Aeronautical Reconnaissance Coverage Geographic Information System(ArcGIS),GeoDa,and other technologies,this study analyzed the spatial-temporal characteristics and driving factors of land use pattern and landscape ecological risk.Results showed that land use structure of the Weihe River basin has changed significantly,with the decrease of cropland and the increase of forest land and construction land.In the past 20 a,cropland has decreased by 7347.70 km2,and cropland was mainly converted into forest land,grassland,and construction land.The fragmentation and dispersion of ecological landscape pattern in the Weihe River basin were improved,and land use pattern became more concentrated.Meanwhile,landscape ecological risk of the Weihe River basin has been improved.Severe landscape ecological risk area decreased by 19,177.87 km2,high landscape ecological risk area decreased by 3904.35 km2,and moderate and low landscape ecological risk areas continued to increase.It is worth noting that landscape ecological risks in the upper reaches of the Weihe River basin are still relatively serious,especially in the contiguous areas of high ecological risk,such as Tianshui,Pingliang,Dingxi areas and some areas of Ningxia Hui Autonomous Region.Landscape ecological risk showed obvious spatial dependence,and high ecological risk area was concentrated.Among the driving factors,population density,precipitation,normalized difference vegetation index(NDVI),and their interactions are the most important factors affecting the landscape ecological risk of the Weihe River basin.The findings significantly contribute to our understanding of the ecological dynamics in the Weihe River basin,providing crucial insights for sustainable management in the region.

关键词： land use ecological risk spatiotemporal distribution geographic detector driving factors

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基于X射线荧光光谱的温稠密物质离化分布实验方法研究

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物理学报 2024年第1期73卷 241-247页

作者：张志宇赵阳青波张继彦林成亮杨国洪韦敏习熊刚吕敏黄成武朱托宋天明赵妍张玉雪张璐李丽灵杜华冰车兴森黎宇坤詹夏宇杨家敏中国工程物理研究院激光聚变研究中心绵阳621900 北京应用物理与计算数学研究所北京100088

受温度及密度等环境效应影响,温稠密物质的电子结构发生显著变化,其理论描述非常复杂,精密实验测量亦极其困难.本文发展了基于X射线荧光光谱研究温稠密物质离化分布的实验方法,结合理论研究有助于深入理解温稠密物质的电子结构变化.在... 详细信息

受温度及密度等环境效应影响,温稠密物质的电子结构发生显著变化,其理论描述非常复杂,精密实验测量亦极其困难.本文发展了基于X射线荧光光谱研究温稠密物质离化分布的实验方法,结合理论研究有助于深入理解温稠密物质的电子结构变化.在万焦耳激光装置上,设计特殊构型黑腔复合加载产生数十eV、近固体密度的稠密Ti物质,利用激光辐照V产生的热发射线泵浦Ti的荧光,并采用晶体谱仪诊断样品的X射线荧光光谱.实验中获得冷样品和加载样品的荧光光谱,观测到加载样品K_(α)及K_(β)荧光谱线相对于冷样品光谱在高能侧的显著变化,结合理论计算解释了加载样品荧光谱线的变化主要来源于其温度上升后离化分布的改变,建立了基于X射线荧光光谱的温稠密物质离化分布实验研究能力.

关键词：温稠密物质电子结构离化分布 X射线荧光光谱

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Modelling the flexural buckling failure of stratified rock slopes based on the multilayer beam model

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Journal of Mountain Science 2019年第5期16卷 1170-1183页

作者： ZHANG Yan-jun NIAN Ting-kai GUO xing-sen CHEN Guang-qi ZHENG Lu State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Department of Civil and Structural Engineering Faculty of Engineering Kyushu University College of Civil Engineering Fuzhou University

The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in mountainous areas. In this study, an analytical approach based on the energy equilibrium principle is presented to solve the flexural buckling stability of stratified rock slopes within the framework of multilayer beam theory. The generalized HoekBrown failure criterion is introduced to reflect the influences of slope size(scale effects) on the buckling stability. Subsequently, numerical and physical modellings from previous literatures are employed to validate the proposed approach. Furthermore, a practical case of Bawang Mountain landslide is also used for the comparative analysis. The study shows that the present analytical approach is capable to provide a more reasonable assessment for the buckling failure of stratified rock slopes, compared with several existing analytical approaches. Finally, a detailed parametric study is implemented, and the results indicate that the effects of rock strength, rock deformation modulus, geological strength index, layer thickness and disturbance degree of rock mass on the buckling failure of stratified rock slopes are more significant than that of rock type and slope angle.

关键词： Slope stability Stratified rock Buckling Scale effect Bawang Mountain

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