【目的】针对传统化学方法测定猕猴桃品质存在工序复杂、费时费力、需破坏性检测等问题,提出一种基于高光谱技术的高效无损检测方法。【方法】以110个米良1号猕猴桃(Actinidia chinensis var.deliciosa‘Miliang-1’)样本为研究对象,利...【目的】针对传统化学方法测定猕猴桃品质存在工序复杂、费时费力、需破坏性检测等问题,提出一种基于高光谱技术的高效无损检测方法。【方法】以110个米良1号猕猴桃(Actinidia chinensis var.deliciosa‘Miliang-1’)样本为研究对象,利用高光谱仪采集不同贮藏时间果实的高光谱反射光谱。利用光谱-理化值共生距离法(sample set partitioning based on joint X-Y distance sampling,SPXY)将猕猴桃样本按照8∶3的数量比例划分为训练集和测试集,统一采用支持向量机(SVM)对比分析标准正态变换(SNV)、多元散射校正(MSC)、一阶导数(1st-D)、二阶导数(2nd-D)、平滑算法(SG)对原始光谱进行预处理。使用遗传算法(genetic algorithm,GA)和随机蛙跳(random frog,RF)对猕猴桃高光谱特征波长进行筛选,结合支持向量回归(SVR)、反向传播神经网络(BP)算法,组合构建猕猴桃品质的回归预测模型。【结果】在组合模型中,可溶性固形物含量的最优模型为1st-D+GA-BP,R^(2)为0.903,RMSE为1.731;可滴定酸含量的最优模型为1st-D+GA-BP,R^(2)为0.857,RMSE为0.225。【结论】应用高光谱技术对米良1号猕猴桃可溶性固形物含量、可滴定酸含量进行无损检测具有可行性。为进一步研究不同品种猕猴桃可溶性固形物含量、可滴定酸含量的无损检测模型奠定了基础。展开更多
Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while exte...Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while extending their lifespan.This paper explores the application of laser-assisted water jet technology in constructing high-quality micro-trap structures on 316L stainless steel,a key material in accelerator manufacturing.The study systematically analyzes the impact of various parameters such as laser repetition frequency,pulse duration,average power,water jet pressure,repeat times,nozzle offset,focal position,offset distance between grooves,and processing speed on the surface morphology of stainless steel.The findings reveal that micro-groove depth increases with higher laser power but decreases with increasing water jet pressure and processing speed.Interestingly,repeat times have minimal effect on depth.On the other hand,micro-groove width increases with higher laser power and repeat times but decreases with processing speed.By optimizing these parameters,the researchers achieved high-quality pound sign-shaped trap structure with consistent dimensions.We tested the secondary electron emission coefficient of the"well"structure.The coefficient is reduced by 0.5 at most compared to before processing,effectively suppressing secondary electron emission.These results offer indispensable insights for the fabrication of micro-trap structures on material surfaces.Laser-assisted water jet technology demonstrates considerable potential in mitigating SEE on metal surfaces.展开更多
The explicit analytical solution of Rosensweig instability spikes'shapes obtained by Navier-Stokes(NS)equation in diverse magnetic field H vertical to the flat free surface of ferrofluids are systematically studie...The explicit analytical solution of Rosensweig instability spikes'shapes obtained by Navier-Stokes(NS)equation in diverse magnetic field H vertical to the flat free surface of ferrofluids are systematically studied experimentally and theoretically.After carefully analyzing and solving the NS equation in elliptic form,the force balanced surface equations of spikes in Rosensweig instability are expressed as cosine wave in perturbated magnetic field and hyperbolic tangent in large magnetic field,whose results both reveal the wave-like nature of Rosensweig instability.The results of hyperbolic tangent form are perfectly fitted to the experimental results in this paper,which indicates that the analytical solution is basically correct.Using the forementioned theoretical results,the total energy of the spike distribution pattern is calculated.By analyzing the energy components under different magnetic field intensities H,the hexagon-square transition of Rosensweig instability is systematically discussed and explained in an explicit way.展开更多
BACKGROUND Diabetes is a metabolic disease characterized by hyperglycemia,which has increased the global medical burden and is also the main cause of death in most countries.AIM To understand the knowledge structure o...BACKGROUND Diabetes is a metabolic disease characterized by hyperglycemia,which has increased the global medical burden and is also the main cause of death in most countries.AIM To understand the knowledge structure of global development status,research focus,and future trend of the relationship between diabetes and metabolomics in the past 20 years.METHODS The articles about the relationship between diabetes and metabolomics in the Web of Science Core Collection were retrieved from 2002 to October 23,2023,and the relevant information was analyzed using CiteSpace6.2.2R(CiteSpace),VOSviewer6.1.18(VOSviewer),and Bibliometrix software under R language.RESULTS A total of 3123 publications were included from 2002 to 2022.In the past two decades,the number of publications and citations in this field has continued to increase.The United States,China,Germany,the United Kingdom,and other relevant funds,institutions,and authors have significantly contributed to this field.Scientific Reports and PLoS One are the journals with the most publications and the most citations.Through keyword co-occurrence and cluster analysis,the closely related keywords are"insulin resistance","risk","obesity","oxidative stress","metabolomics","metabolites"and"biomarkers".Keyword clustering included cardiovascular disease,gut microbiota,metabonomics,diabetic nephropathy,molecular docking,gestational diabetes mellitus,oxidative stress,and insulin resistance.Burst detection analysis of keyword depicted that"Gene","microbiota","validation","kidney disease","antioxidant activity","untargeted metabolomics","management",and"accumulation"are knowledge frontiers in recent years.CONCLUSION The relationship between metabolomics and diabetes is receiving extensive attention.Diabetic nephropathy,diabetic cardiovascular disease,and kidney disease are key diseases for future research in this field.Gut microbiota,molecular docking,and untargeted metabolomics are key research directions in the future.Antioxidant activity,gene,validation,mass spectrometry,management,and accumulation are at the forefront of knowledge frontiers in this field.展开更多
在儿童友好城市建设中,儿童参与是获取儿童诉求的关键途径。文章基于Web of Science文献数据库和中国知网文献数据库,借助Bibliometrix的R语言包,对基本概况、研究方向与热点研究趋势等方面进行计量分析。结果显示,在国内该研究目前处...在儿童友好城市建设中,儿童参与是获取儿童诉求的关键途径。文章基于Web of Science文献数据库和中国知网文献数据库,借助Bibliometrix的R语言包,对基本概况、研究方向与热点研究趋势等方面进行计量分析。结果显示,在国内该研究目前处于发展阶段,研究方向主要集中在儿童参与权利保障、儿童参与方法迭代和公共空间实践探索三方面,儿童参与公共空间的实践创新是未来研究的焦点。基于国内外研究的对比,提出相关建议,以期为后续儿童参与城市建设研究提供参考。展开更多
文摘【目的】针对传统化学方法测定猕猴桃品质存在工序复杂、费时费力、需破坏性检测等问题,提出一种基于高光谱技术的高效无损检测方法。【方法】以110个米良1号猕猴桃(Actinidia chinensis var.deliciosa‘Miliang-1’)样本为研究对象,利用高光谱仪采集不同贮藏时间果实的高光谱反射光谱。利用光谱-理化值共生距离法(sample set partitioning based on joint X-Y distance sampling,SPXY)将猕猴桃样本按照8∶3的数量比例划分为训练集和测试集,统一采用支持向量机(SVM)对比分析标准正态变换(SNV)、多元散射校正(MSC)、一阶导数(1st-D)、二阶导数(2nd-D)、平滑算法(SG)对原始光谱进行预处理。使用遗传算法(genetic algorithm,GA)和随机蛙跳(random frog,RF)对猕猴桃高光谱特征波长进行筛选,结合支持向量回归(SVR)、反向传播神经网络(BP)算法,组合构建猕猴桃品质的回归预测模型。【结果】在组合模型中,可溶性固形物含量的最优模型为1st-D+GA-BP,R^(2)为0.903,RMSE为1.731;可滴定酸含量的最优模型为1st-D+GA-BP,R^(2)为0.857,RMSE为0.225。【结论】应用高光谱技术对米良1号猕猴桃可溶性固形物含量、可滴定酸含量进行无损检测具有可行性。为进一步研究不同品种猕猴桃可溶性固形物含量、可滴定酸含量的无损检测模型奠定了基础。
文摘Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while extending their lifespan.This paper explores the application of laser-assisted water jet technology in constructing high-quality micro-trap structures on 316L stainless steel,a key material in accelerator manufacturing.The study systematically analyzes the impact of various parameters such as laser repetition frequency,pulse duration,average power,water jet pressure,repeat times,nozzle offset,focal position,offset distance between grooves,and processing speed on the surface morphology of stainless steel.The findings reveal that micro-groove depth increases with higher laser power but decreases with increasing water jet pressure and processing speed.Interestingly,repeat times have minimal effect on depth.On the other hand,micro-groove width increases with higher laser power and repeat times but decreases with processing speed.By optimizing these parameters,the researchers achieved high-quality pound sign-shaped trap structure with consistent dimensions.We tested the secondary electron emission coefficient of the"well"structure.The coefficient is reduced by 0.5 at most compared to before processing,effectively suppressing secondary electron emission.These results offer indispensable insights for the fabrication of micro-trap structures on material surfaces.Laser-assisted water jet technology demonstrates considerable potential in mitigating SEE on metal surfaces.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51735006,51927810,and U1837206)Beijing Municipal Natural Science Foundation(Grant No.3182013).
文摘The explicit analytical solution of Rosensweig instability spikes'shapes obtained by Navier-Stokes(NS)equation in diverse magnetic field H vertical to the flat free surface of ferrofluids are systematically studied experimentally and theoretically.After carefully analyzing and solving the NS equation in elliptic form,the force balanced surface equations of spikes in Rosensweig instability are expressed as cosine wave in perturbated magnetic field and hyperbolic tangent in large magnetic field,whose results both reveal the wave-like nature of Rosensweig instability.The results of hyperbolic tangent form are perfectly fitted to the experimental results in this paper,which indicates that the analytical solution is basically correct.Using the forementioned theoretical results,the total energy of the spike distribution pattern is calculated.By analyzing the energy components under different magnetic field intensities H,the hexagon-square transition of Rosensweig instability is systematically discussed and explained in an explicit way.
基金Supported by National Natural Science Foundation of China,No.U21A20411and the Graduate Research and Innovation Project of Hunan Province,No.CX20220772.
文摘BACKGROUND Diabetes is a metabolic disease characterized by hyperglycemia,which has increased the global medical burden and is also the main cause of death in most countries.AIM To understand the knowledge structure of global development status,research focus,and future trend of the relationship between diabetes and metabolomics in the past 20 years.METHODS The articles about the relationship between diabetes and metabolomics in the Web of Science Core Collection were retrieved from 2002 to October 23,2023,and the relevant information was analyzed using CiteSpace6.2.2R(CiteSpace),VOSviewer6.1.18(VOSviewer),and Bibliometrix software under R language.RESULTS A total of 3123 publications were included from 2002 to 2022.In the past two decades,the number of publications and citations in this field has continued to increase.The United States,China,Germany,the United Kingdom,and other relevant funds,institutions,and authors have significantly contributed to this field.Scientific Reports and PLoS One are the journals with the most publications and the most citations.Through keyword co-occurrence and cluster analysis,the closely related keywords are"insulin resistance","risk","obesity","oxidative stress","metabolomics","metabolites"and"biomarkers".Keyword clustering included cardiovascular disease,gut microbiota,metabonomics,diabetic nephropathy,molecular docking,gestational diabetes mellitus,oxidative stress,and insulin resistance.Burst detection analysis of keyword depicted that"Gene","microbiota","validation","kidney disease","antioxidant activity","untargeted metabolomics","management",and"accumulation"are knowledge frontiers in recent years.CONCLUSION The relationship between metabolomics and diabetes is receiving extensive attention.Diabetic nephropathy,diabetic cardiovascular disease,and kidney disease are key diseases for future research in this field.Gut microbiota,molecular docking,and untargeted metabolomics are key research directions in the future.Antioxidant activity,gene,validation,mass spectrometry,management,and accumulation are at the forefront of knowledge frontiers in this field.
文摘在儿童友好城市建设中,儿童参与是获取儿童诉求的关键途径。文章基于Web of Science文献数据库和中国知网文献数据库,借助Bibliometrix的R语言包,对基本概况、研究方向与热点研究趋势等方面进行计量分析。结果显示,在国内该研究目前处于发展阶段,研究方向主要集中在儿童参与权利保障、儿童参与方法迭代和公共空间实践探索三方面,儿童参与公共空间的实践创新是未来研究的焦点。基于国内外研究的对比,提出相关建议,以期为后续儿童参与城市建设研究提供参考。
