分数阶微分(fractional order derivative,FOD)是重要的数学分支,它将经典的整数阶扩展到任意阶,可进一步捕捉到光谱的细节特征。该文基于高光谱影像和野外土壤样本铬(Cr)元素含量建立土壤重金属高光谱反演模型,首先,根据野外样本坐标...分数阶微分(fractional order derivative,FOD)是重要的数学分支,它将经典的整数阶扩展到任意阶,可进一步捕捉到光谱的细节特征。该文基于高光谱影像和野外土壤样本铬(Cr)元素含量建立土壤重金属高光谱反演模型,首先,根据野外样本坐标信息提取像元光谱,同时按照欧式距离最短原则提取邻近像元光谱扩充样本数量;其次,对扩充后样本进行Savitzky-Golay(SG)滤波、多元散射校正处理,在此基础上进行FOD光谱变换,采用竞争自适应重加权采样算法(competitive adaptive reweighted sampling,CARS)筛选特征波段组合;最后,根据筛选的特征组合,建立偏最小二乘回归(partial least squares regression,PLSR)模型,并进行精度评价。结果发现,扩充样本可有效缓解反演模型的“过拟合”现象,提升模型的精度和稳定性;当FOD的阶数为1.8时,PLSR反演模型的训练集和测试集精度最高,模型适应性、稳定性最强,训练集R^(2)为0.8962、相对分析误差为3.1044,测试集R^(2)为0.7556、相对分析误差为2.0226,均方根误差均最小,分别为16.331 mg/kg和17.094 mg/kg,模型为能够近似预测级别。该文基于国产高光谱ZY-102E数据建立硫铁矿区Cr元素含量反演模型,可在一定程度上促进国产高光谱数据土壤重金属含量反演研究,为硫铁矿区土壤重金属污染防治提供技术支撑。展开更多
Aerodynamic research on road cars was reviewed in this work under the thread of reducing drag,with the awareness that this may succeed in effectively decreasing the carbon footprint of transportation.First,a selection...Aerodynamic research on road cars was reviewed in this work under the thread of reducing drag,with the awareness that this may succeed in effectively decreasing the carbon footprint of transportation.First,a selection of studies was presented to focus on the most important aerodynamic features of the flow around realistic car body shapes.Then,the discussion was organized around three pillars related to passive flow control,active flow control and active aerodynamics.Both experimental and numerical investigations were included to provide a comprehensive overview.A clear distinction was made between simplified and realistic car models,as well as production vehicles(within the limits of restricted access information).Moreover,a short essay was dedicated to electric vehicles,for which aerodynamics matters,especially at highway speeds.Last,the impact of aerodynamic principles on the design of current and future vehicle fleet was assessed,honestly admitting that recent market trends must be reversed to turn decarbonization goals into reality and damp the effects of global warming.展开更多
In this study,eight different varieties of maize seeds were used as the research objects.Conduct 81 types of combined preprocessing on the original spectra.Through comparison,Savitzky-Golay(SG)-multivariate scattering...In this study,eight different varieties of maize seeds were used as the research objects.Conduct 81 types of combined preprocessing on the original spectra.Through comparison,Savitzky-Golay(SG)-multivariate scattering correction(MSC)-maximum-minimum normalization(MN)was identified as the optimal preprocessing technique.The competitive adaptive reweighted sampling(CARS),successive projections algorithm(SPA),and their combined methods were employed to extract feature wavelengths.Classification models based on back propagation(BP),support vector machine(SVM),random forest(RF),and partial least squares(PLS)were established using full-band data and feature wavelengths.Among all models,the(CARS-SPA)-BP model achieved the highest accuracy rate of 98.44%.This study offers novel insights and methodologies for the rapid and accurate identification of corn seeds as well as other crop seeds.展开更多
This study systematically analyzes the genre structure and linguistic features of 42 English abstracts from six internationally renowned medical journals,based on the revised CARS model proposed by Swales.The research...This study systematically analyzes the genre structure and linguistic features of 42 English abstracts from six internationally renowned medical journals,based on the revised CARS model proposed by Swales.The research findings indicate that medical abstracts typically follow a three-step structure:“Establishing a Research Territory-Establishing a Research Niche-Occupying the Niche”,where the steps“Research Purpose”and“Research Results”are the most frequently utilized,forming the core content of the abstracts.Within the sequence of moves,81%conform to conventional patterns,while a minority of samples exhibit unconventional structures such as inversion,cycling,and repetition.In terms of linguistic features,the present simple tense and active voice are predominantly used,reflecting the universality of the research and the author’s agency;conversely,the simple past tense and passive voice are primarily employed to describe research methods and processes.This study reveals the writing conventions of medical abstracts,providing empirical evidence and genre reference for non-native scholars in the preparation and publication of their work in international journals.展开更多
Purpose-Weathering steel has excellent resistance to atmospheric corrosion,but still faces complex environmental corrosion problems during long-term operation.This paper mainly studies the corrosion problem of weather...Purpose-Weathering steel has excellent resistance to atmospheric corrosion,but still faces complex environmental corrosion problems during long-term operation.This paper mainly studies the corrosion problem of weather resistant steel materials for railway freight car bodies with a load capacity of 70 tons.Design/methodology/approach-The paper analyzes the corrosion characteristics of weather resistant steel materials for truck bodies through macroscopic and microscopic methods including metallographic microscopy,scanning electron microscopy,energy dispersive spectroscopy and X-ray diffraction.Electrochemical analysis shows that the rust layer on the surface of weathering steel changes the surface state of the material,and also proves that weathering steel used in trucks undergoes electrochemical corrosion under atmospheric corrosion.At the same time,ion chromatography technology is used to study the corrosive ions mainly present in the residual liquid and foam solution inside the vehicle body.Findings-The corrosion of truck body materials is mainly electrochemical corrosion,and the corrosion of door materials is more obvious than that of other parts.The corrosion products are mainly Fe oxides and hydroxides.There are high concentrations of Cl-and SO42-ions in the residual liquid and foam solution at the bottom of the freight car,which are the main factors causing corrosion of the railway freight car body.Originality/value-The foam adhesive around the door panel is in a moist state for a long time,and corrosive ions will accelerate the electrochemical corrosion of the weather resistant steel material of the door panel.Therefore,the corrosion of the cargo door panel is more severe than other components.展开更多
本文以构式语法理论为基础,结合Swales提出的CARS (Create A Research Space)模型,对俄语语言学类核心期刊中的学术引言语篇进行语步划分与构式分析,旨在揭示俄语学术写作中语步结构与语言构式之间的互动规律。研究识别出三大语步(M1-M2...本文以构式语法理论为基础,结合Swales提出的CARS (Create A Research Space)模型,对俄语语言学类核心期刊中的学术引言语篇进行语步划分与构式分析,旨在揭示俄语学术写作中语步结构与语言构式之间的互动规律。研究识别出三大语步(M1-M2-M3)中共计32类典型构式,发现各语步在构式类型、句法形式与语用功能上具有显著差异。M1语步偏好使用领域提示与引证型构式,M2语步侧重限制性判断与批评构式,M3语步则高度依赖程式化的目标表达与方法展望构式。此外,构式呈现出结构固定性与语用灵活性并存的特征,反映出学术引言中的模板化趋势与个体写作策略的结合。本文研究不仅丰富了构式语法在篇章层面的应用路径,也为俄语学术写作教学与文本建模提供了初步的参考与语料基础。展开更多
Cleaner air,lower dependency on oil,and lower emissions are just a few reasons to move away from combustion cars.In the wake of the emergence of more environmentally friendly technology,some countries have decided to ...Cleaner air,lower dependency on oil,and lower emissions are just a few reasons to move away from combustion cars.In the wake of the emergence of more environmentally friendly technology,some countries have decided to move away from traditional cars towards electric vehicles (EVs).The rise of the EV industry has created a shift in energy demand from oil-based to battery-based.展开更多
文摘Aerodynamic research on road cars was reviewed in this work under the thread of reducing drag,with the awareness that this may succeed in effectively decreasing the carbon footprint of transportation.First,a selection of studies was presented to focus on the most important aerodynamic features of the flow around realistic car body shapes.Then,the discussion was organized around three pillars related to passive flow control,active flow control and active aerodynamics.Both experimental and numerical investigations were included to provide a comprehensive overview.A clear distinction was made between simplified and realistic car models,as well as production vehicles(within the limits of restricted access information).Moreover,a short essay was dedicated to electric vehicles,for which aerodynamics matters,especially at highway speeds.Last,the impact of aerodynamic principles on the design of current and future vehicle fleet was assessed,honestly admitting that recent market trends must be reversed to turn decarbonization goals into reality and damp the effects of global warming.
基金supported by the Science and Technology Development Plan Project of Jilin Provincial Department of Science and Technology (No.20220203112S)the Jilin Provincial Department of Education Science and Technology Research Project (No.JJKH20210039KJ)。
文摘In this study,eight different varieties of maize seeds were used as the research objects.Conduct 81 types of combined preprocessing on the original spectra.Through comparison,Savitzky-Golay(SG)-multivariate scattering correction(MSC)-maximum-minimum normalization(MN)was identified as the optimal preprocessing technique.The competitive adaptive reweighted sampling(CARS),successive projections algorithm(SPA),and their combined methods were employed to extract feature wavelengths.Classification models based on back propagation(BP),support vector machine(SVM),random forest(RF),and partial least squares(PLS)were established using full-band data and feature wavelengths.Among all models,the(CARS-SPA)-BP model achieved the highest accuracy rate of 98.44%.This study offers novel insights and methodologies for the rapid and accurate identification of corn seeds as well as other crop seeds.
文摘This study systematically analyzes the genre structure and linguistic features of 42 English abstracts from six internationally renowned medical journals,based on the revised CARS model proposed by Swales.The research findings indicate that medical abstracts typically follow a three-step structure:“Establishing a Research Territory-Establishing a Research Niche-Occupying the Niche”,where the steps“Research Purpose”and“Research Results”are the most frequently utilized,forming the core content of the abstracts.Within the sequence of moves,81%conform to conventional patterns,while a minority of samples exhibit unconventional structures such as inversion,cycling,and repetition.In terms of linguistic features,the present simple tense and active voice are predominantly used,reflecting the universality of the research and the author’s agency;conversely,the simple past tense and passive voice are primarily employed to describe research methods and processes.This study reveals the writing conventions of medical abstracts,providing empirical evidence and genre reference for non-native scholars in the preparation and publication of their work in international journals.
基金supported by Research and Development Plan of China Railway Group(N2023J065).
文摘Purpose-Weathering steel has excellent resistance to atmospheric corrosion,but still faces complex environmental corrosion problems during long-term operation.This paper mainly studies the corrosion problem of weather resistant steel materials for railway freight car bodies with a load capacity of 70 tons.Design/methodology/approach-The paper analyzes the corrosion characteristics of weather resistant steel materials for truck bodies through macroscopic and microscopic methods including metallographic microscopy,scanning electron microscopy,energy dispersive spectroscopy and X-ray diffraction.Electrochemical analysis shows that the rust layer on the surface of weathering steel changes the surface state of the material,and also proves that weathering steel used in trucks undergoes electrochemical corrosion under atmospheric corrosion.At the same time,ion chromatography technology is used to study the corrosive ions mainly present in the residual liquid and foam solution inside the vehicle body.Findings-The corrosion of truck body materials is mainly electrochemical corrosion,and the corrosion of door materials is more obvious than that of other parts.The corrosion products are mainly Fe oxides and hydroxides.There are high concentrations of Cl-and SO42-ions in the residual liquid and foam solution at the bottom of the freight car,which are the main factors causing corrosion of the railway freight car body.Originality/value-The foam adhesive around the door panel is in a moist state for a long time,and corrosive ions will accelerate the electrochemical corrosion of the weather resistant steel material of the door panel.Therefore,the corrosion of the cargo door panel is more severe than other components.
文摘本文以构式语法理论为基础,结合Swales提出的CARS (Create A Research Space)模型,对俄语语言学类核心期刊中的学术引言语篇进行语步划分与构式分析,旨在揭示俄语学术写作中语步结构与语言构式之间的互动规律。研究识别出三大语步(M1-M2-M3)中共计32类典型构式,发现各语步在构式类型、句法形式与语用功能上具有显著差异。M1语步偏好使用领域提示与引证型构式,M2语步侧重限制性判断与批评构式,M3语步则高度依赖程式化的目标表达与方法展望构式。此外,构式呈现出结构固定性与语用灵活性并存的特征,反映出学术引言中的模板化趋势与个体写作策略的结合。本文研究不仅丰富了构式语法在篇章层面的应用路径,也为俄语学术写作教学与文本建模提供了初步的参考与语料基础。
文摘Cleaner air,lower dependency on oil,and lower emissions are just a few reasons to move away from combustion cars.In the wake of the emergence of more environmentally friendly technology,some countries have decided to move away from traditional cars towards electric vehicles (EVs).The rise of the EV industry has created a shift in energy demand from oil-based to battery-based.
