Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials ...Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method(VFM) is applied to characterize all the mechanical parameters(Q, Q, Q, Q) using the full-field strain,which is measured by digital image correlation(DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method(FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30?. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters(Q, Q, Q, Q) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants(Q, Q, Q, Q) were determined from the test with an angle of 27?.展开更多
Image caption generation is an essential task in computer vision and image understanding.Contemporary image caption generation models usually use the encoder-decoder model as the underlying network structure.However,i...Image caption generation is an essential task in computer vision and image understanding.Contemporary image caption generation models usually use the encoder-decoder model as the underlying network structure.However,in the traditional Encoder-Decoder architectures,only the global features of the images are extracted,while the local information of the images is not well utilized.This paper proposed an Encoder-Decoder model based on fused features and a novel mechanism for correcting the generated caption text.We use VGG16 and Faster R-CNN to extract global and local features in the encoder first.Then,we train the bidirectional LSTM network with the fused features in the decoder.Finally,the local features extracted is used to correct the caption text.The experiment results prove that the effectiveness of the proposed method.展开更多
Emission quenching resulting from fluorophore aggregation has long been a significant challenge in optimizing emission-based technologies,such as fluorescence imaging and optoelectronic devices.Alleviating this quench...Emission quenching resulting from fluorophore aggregation has long been a significant challenge in optimizing emission-based technologies,such as fluorescence imaging and optoelectronic devices.Alleviating this quenching in aggregates is crucial,yet progress is impeded by the limited understanding of the nature and impact of aggregates on emission.Here,we elucidate the critical role of dimeric aggregate(dimer)in alleviating second near-infrared(NIR-II,900-1700 nm)emission quenching from ring-fused fluorophore 4F for superior fluorescence imaging.Spectral decomposition and molecular dynamics simulations demonstrate the predominance of dimer populations in 4F aggregates.Notably,dimers exhibit significantly weaker emission but intense intermolecular nonradiative(interNR)decay compared to monomers,as demonstrated by ultrafast spectra and quantum calculation.Therefore,the predominant population of dimers with weak emission and pronounced interNR feature underlies the emission quenching in 4F aggregates.This discovery guides the preparation of ultrabright NIR-II 4F nanofluorophore(4F NP3s)by decreasing dimer populations,which show 5-fold greater NIR-II brightness than indocyanine green,enabling superior resolution in visualizing blood vessels.This work offers valuable insights into aggregation-caused quenching,with broad implications extending far beyond NIR-II fluorescence imaging.展开更多
研究遥感图像融合性能的客观评价问题,分析当前遥感图像融合效果评估方法特点的基础上,提出一种新的遥感图像融合效果评估方法——基于奇异值分解(SVD,Singular Value Decomposition)的方法.利用源图像与融合结果图像的奇异值差异,测量...研究遥感图像融合性能的客观评价问题,分析当前遥感图像融合效果评估方法特点的基础上,提出一种新的遥感图像融合效果评估方法——基于奇异值分解(SVD,Singular Value Decomposition)的方法.利用源图像与融合结果图像的奇异值差异,测量它们之间能量信息失真情况,从而进行融合算法的评估.仿真实验从两方面入手,当融合源图像中含有SAR(Synthetic Aperlure Radar)图像时,对比Piella和Xydeas评估方法较为有效;另一方面,对多类型传感器、不同方法的像素级融合结果进行评估,与主观评价结果对比具有较高的一致性.这种客观评估方法能够较好地反映多类遥感图像融合的质量,是一种实现简单、高效、较为通用的遥感图像融合效果评估方法.展开更多
基金the financial support from the National Natural Science Foundation of China (Grants 11672153, 11232008, and 11227801)
文摘Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method(VFM) is applied to characterize all the mechanical parameters(Q, Q, Q, Q) using the full-field strain,which is measured by digital image correlation(DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method(FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30?. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters(Q, Q, Q, Q) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants(Q, Q, Q, Q) were determined from the test with an angle of 27?.
基金This work is supported by the National Natural Science Foundation of China(6187223).
文摘Image caption generation is an essential task in computer vision and image understanding.Contemporary image caption generation models usually use the encoder-decoder model as the underlying network structure.However,in the traditional Encoder-Decoder architectures,only the global features of the images are extracted,while the local information of the images is not well utilized.This paper proposed an Encoder-Decoder model based on fused features and a novel mechanism for correcting the generated caption text.We use VGG16 and Faster R-CNN to extract global and local features in the encoder first.Then,we train the bidirectional LSTM network with the fused features in the decoder.Finally,the local features extracted is used to correct the caption text.The experiment results prove that the effectiveness of the proposed method.
基金support by the National Natural Science Foundation of China(No.62175201,62288102,and 52373142)the Fundamental Research Funds for the Central Universities,and the open research fund of State Key Laboratory of Organic Electronics and Information Displays.
文摘Emission quenching resulting from fluorophore aggregation has long been a significant challenge in optimizing emission-based technologies,such as fluorescence imaging and optoelectronic devices.Alleviating this quenching in aggregates is crucial,yet progress is impeded by the limited understanding of the nature and impact of aggregates on emission.Here,we elucidate the critical role of dimeric aggregate(dimer)in alleviating second near-infrared(NIR-II,900-1700 nm)emission quenching from ring-fused fluorophore 4F for superior fluorescence imaging.Spectral decomposition and molecular dynamics simulations demonstrate the predominance of dimer populations in 4F aggregates.Notably,dimers exhibit significantly weaker emission but intense intermolecular nonradiative(interNR)decay compared to monomers,as demonstrated by ultrafast spectra and quantum calculation.Therefore,the predominant population of dimers with weak emission and pronounced interNR feature underlies the emission quenching in 4F aggregates.This discovery guides the preparation of ultrabright NIR-II 4F nanofluorophore(4F NP3s)by decreasing dimer populations,which show 5-fold greater NIR-II brightness than indocyanine green,enabling superior resolution in visualizing blood vessels.This work offers valuable insights into aggregation-caused quenching,with broad implications extending far beyond NIR-II fluorescence imaging.
文摘研究遥感图像融合性能的客观评价问题,分析当前遥感图像融合效果评估方法特点的基础上,提出一种新的遥感图像融合效果评估方法——基于奇异值分解(SVD,Singular Value Decomposition)的方法.利用源图像与融合结果图像的奇异值差异,测量它们之间能量信息失真情况,从而进行融合算法的评估.仿真实验从两方面入手,当融合源图像中含有SAR(Synthetic Aperlure Radar)图像时,对比Piella和Xydeas评估方法较为有效;另一方面,对多类型传感器、不同方法的像素级融合结果进行评估,与主观评价结果对比具有较高的一致性.这种客观评估方法能够较好地反映多类遥感图像融合的质量,是一种实现简单、高效、较为通用的遥感图像融合效果评估方法.
