Aiming at the problems of low reliability and complex operation of traditional coin-tap test of composite material,this paper introduces the grey system theory and achieves better performance.The response signals of c...Aiming at the problems of low reliability and complex operation of traditional coin-tap test of composite material,this paper introduces the grey system theory and achieves better performance.The response signals of coin-tap are classified through the grey clustering based on relation analysis,and corresponding improvements are made to the calculation method of the relation degree of nearness.First,the time history of acceleration is taken as the system behavior sequence.The improved correlation calculation method is used to solve the relation degree of nearness between the sequences,and the matrix of degree of grey relation is constructed based on this.Then,the sequence groups are summarized through the matrix,and the response signals of coin-tap are qualitatively classified according to the location of the reference sequence.Finally,the defect detection of composite materials is completed without pre-testing.The test results show that the accuracy of the coin-tap test based on improved grey clustering reaches 100%,which simplifies the operation steps while ensuring the reliability of the coin-tap test results.展开更多
The development of stimuli-responsive circularly polarized luminescence(CPL)materials is quite attractive but challenging.Here,a pair of atomically precise enan-tiomers R/S-Ag20 nanoclusters has been synthesized using...The development of stimuli-responsive circularly polarized luminescence(CPL)materials is quite attractive but challenging.Here,a pair of atomically precise enan-tiomers R/S-Ag20 nanoclusters has been synthesized using chiral acid ligands.And then,stimuli-responsive CPL materials were developed by assembling the chiral silver nanoclusters with an achiral bridging ligand.The atomically precise silver cluster-assembled materials produce CPL with a dissymmetry factor(|glum|)of 1×10-3,through the high-efficiency chiral induction process.More interestingly,the single CPL band at room temperature could quickly transform into highly separated dual CPL emissions at low temperature.This study provides a new strategy for the rational functionalization of chiral silver clusters in preparing cluster-based CPL emitters and enriches the types of stimuli-responsive CPL materials.展开更多
A new type of soft X-ray source, i.e. a plasma-based X-ray laser, is found to be promising to conduct transient measurement. By means of picosecond X-ray laser speckles, the dynamic microscopic polarization clusters w...A new type of soft X-ray source, i.e. a plasma-based X-ray laser, is found to be promising to conduct transient measurement. By means of picosecond X-ray laser speckles, the dynamic microscopic polarization clusters within cubic (paraelectric) BaTiO3 was directly observed and characterized in a microscopic scale for the first time. This opens a way to study this type of clusters, which usually manifest large external-field response for ferroelectric materials.展开更多
为加强危险货物道路运输风险源头管控,以危货运输车辆行驶轨迹数据为分析对象,研究安全、经济且符合企业自身偏好的道路运输路径优化选择问题,提出了基于偏好、上下文感知的危险货物道路运输个性化路径推荐方法。首先对危货运输车辆历...为加强危险货物道路运输风险源头管控,以危货运输车辆行驶轨迹数据为分析对象,研究安全、经济且符合企业自身偏好的道路运输路径优化选择问题,提出了基于偏好、上下文感知的危险货物道路运输个性化路径推荐方法。首先对危货运输车辆历史轨迹数据进行处理,通过提取路径安全和经济性特征学习危货运输企业的路径偏好,在此基础上,综合考虑偏好向量间的距离和方向相似性,提出了改进的K-means偏好聚类算法(improved K-means clustering algorithm based on distance and direction similarity measurement,DDM-K-means),获取了路径偏好类别;其次,依据运输任务执行的时间、天气、运距三方面信息,建立了路径上下文向量,并运用Rock聚类算法划分路径的上下文类别,与路径偏好类别共同构成路径信息;最终,基于神经协同过滤提出了危险货物道路运输路径选择优化算法(optimal route selection algorithm based on neural collaborative filtering,NCF-ORS),得到了危货运输企业对各路径类别的偏好排序,从而为企业推荐最优路径。与基线算法比较分析,结果表明危险货物道路运输个性化路径推荐方法<DDM-K-means,NCF-ORS>,平均绝对百分比误差最低。研究结果有助于挖掘车辆轨迹数据中更多的潜在信息,提升个性化路径推荐能力,可为危货运输企业的选线问题提供决策支持。展开更多
基金National Key Research and Development Project of China(No.2018YFB1701200)。
文摘Aiming at the problems of low reliability and complex operation of traditional coin-tap test of composite material,this paper introduces the grey system theory and achieves better performance.The response signals of coin-tap are classified through the grey clustering based on relation analysis,and corresponding improvements are made to the calculation method of the relation degree of nearness.First,the time history of acceleration is taken as the system behavior sequence.The improved correlation calculation method is used to solve the relation degree of nearness between the sequences,and the matrix of degree of grey relation is constructed based on this.Then,the sequence groups are summarized through the matrix,and the response signals of coin-tap are qualitatively classified according to the location of the reference sequence.Finally,the defect detection of composite materials is completed without pre-testing.The test results show that the accuracy of the coin-tap test based on improved grey clustering reaches 100%,which simplifies the operation steps while ensuring the reliability of the coin-tap test results.
基金National Natural Science Foundation of China,Grant/Award Number:92061201 U21A20277Thousand Talents(Zhongyuan Scholars)Program of Henan Province,Grant/Award Number:234000510007Excellent Youth Foundation of Henan Scientific Committee,Grant/Award Number:232300421022。
文摘The development of stimuli-responsive circularly polarized luminescence(CPL)materials is quite attractive but challenging.Here,a pair of atomically precise enan-tiomers R/S-Ag20 nanoclusters has been synthesized using chiral acid ligands.And then,stimuli-responsive CPL materials were developed by assembling the chiral silver nanoclusters with an achiral bridging ligand.The atomically precise silver cluster-assembled materials produce CPL with a dissymmetry factor(|glum|)of 1×10-3,through the high-efficiency chiral induction process.More interestingly,the single CPL band at room temperature could quickly transform into highly separated dual CPL emissions at low temperature.This study provides a new strategy for the rational functionalization of chiral silver clusters in preparing cluster-based CPL emitters and enriches the types of stimuli-responsive CPL materials.
文摘A new type of soft X-ray source, i.e. a plasma-based X-ray laser, is found to be promising to conduct transient measurement. By means of picosecond X-ray laser speckles, the dynamic microscopic polarization clusters within cubic (paraelectric) BaTiO3 was directly observed and characterized in a microscopic scale for the first time. This opens a way to study this type of clusters, which usually manifest large external-field response for ferroelectric materials.
文摘为加强危险货物道路运输风险源头管控,以危货运输车辆行驶轨迹数据为分析对象,研究安全、经济且符合企业自身偏好的道路运输路径优化选择问题,提出了基于偏好、上下文感知的危险货物道路运输个性化路径推荐方法。首先对危货运输车辆历史轨迹数据进行处理,通过提取路径安全和经济性特征学习危货运输企业的路径偏好,在此基础上,综合考虑偏好向量间的距离和方向相似性,提出了改进的K-means偏好聚类算法(improved K-means clustering algorithm based on distance and direction similarity measurement,DDM-K-means),获取了路径偏好类别;其次,依据运输任务执行的时间、天气、运距三方面信息,建立了路径上下文向量,并运用Rock聚类算法划分路径的上下文类别,与路径偏好类别共同构成路径信息;最终,基于神经协同过滤提出了危险货物道路运输路径选择优化算法(optimal route selection algorithm based on neural collaborative filtering,NCF-ORS),得到了危货运输企业对各路径类别的偏好排序,从而为企业推荐最优路径。与基线算法比较分析,结果表明危险货物道路运输个性化路径推荐方法<DDM-K-means,NCF-ORS>,平均绝对百分比误差最低。研究结果有助于挖掘车辆轨迹数据中更多的潜在信息,提升个性化路径推荐能力,可为危货运输企业的选线问题提供决策支持。
