Ferritic steel with a nominal composition of Fe-14Cr-3W-0.42Ti-0.32Y was prepared by mixing gas-atomized prealloyed powder and mechanically alloyed powder. The microstructure is much different fxom other ferritic stee...Ferritic steel with a nominal composition of Fe-14Cr-3W-0.42Ti-0.32Y was prepared by mixing gas-atomized prealloyed powder and mechanically alloyed powder. The microstructure is much different fxom other ferritic steels with the same composition and prepared via only mechanically alloyed powder. A bi-modal structure, which consists of pure ferritic grains and martensitic grains, was obtained after hot forging and air cooling. A phase transformation of αbcc→γfcc→α＇bcc was also discovered in microstructural observation. The bi-modal microstructure shows a good combination of high strength and high ductility.展开更多
β titanium alloys with bi-modal structure which exhibit improved strength-ductility combination and fatigue property are widely used in aviation and aerospace industry.However,owing to the small size of primary α(α...β titanium alloys with bi-modal structure which exhibit improved strength-ductility combination and fatigue property are widely used in aviation and aerospace industry.However,owing to the small size of primary α(αp) and nano-scaled multi variant distribution of secondary α platelets(αs),investigating the deformation behavior is really a challenging work.In this work,by applying transmission electron microscopy(TEM),the slip behavior in αp and transformed β matrix with different tensile strain was studied.After α/β solution treatment,the initial dislocation slips on {110} plane with <1 1 1> direction in β matrix.During furtherdeformation,(110),(101) and(1 1 2) multi slip is generated which shows a long straight cro s sing configuration.Dislocation cell is exhibited in β matrix at tensile strain above 20 %.Diffe rent from the solid solution treated sample,high density wavy dislocations are generated in transformedβ matrix.High fraction fine as hinders dislocation motion in β matrix effectively which in turn dominates the strength of the alloy.In primary α phase(αp),a core-shell structure is formed during deformation.Both pyramidal a+c slip and prismatic/basal a slip are generated in the shell layer.In core region,plastic deformation is governed by prismatic/basal a slip.Formation of the core-shell structure is the physical origin of the improved ductility.On one hand,the work hardening layer(shell) improves the strength of αp,which could deform compatibly with the hard transformed β matrix.Meanwhile,the center area(core) deforms homogeneously which will sustain plastic strain effectively and increase the ductility.This paper studies the slip behavior and reveals the origin of the improved strength-ductility combination in Bi-modal structure on a microscopic way,which will give theoretical advises for developing the next generation high strength β titanium alloys.展开更多
Olfactory receptors(ORs)play a key role in the prime sensorial perception,being highly relevant for intra/interspecific interactions.ORs are a subgroup of G-protein coupled receptors that exhibit highly complex subgen...Olfactory receptors(ORs)play a key role in the prime sensorial perception,being highly relevant for intra/interspecific interactions.ORs are a subgroup of G-protein coupled receptors that exhibit highly complex subgenomes in vertebrates.However,OR repertoires remain poorly studied in fish lineages,precluding finely retracing their origin,evolution,and diversification,especially in the most basal groups.Here,we conduct an exhaustive gene screening upon 43 high-quality fish genomes exhibiting varied gene repertoires(2e583 genes).While the early vertebrates performed gas exchange through gills,we hypothesize that the emergence of new breathing structures(swim bladder and paired lungs)in early osteichthyans may be associated with expansions in the ORs gene families sensitive to airborne molecules.Additionally,we verify that the OR repertoire of moderns actinopterygians has not increased as expected following a whole genome duplication,likely due to regulatory mechanisms compensating the gene load excess.Finally,we identify 25 distinct OR families,allowing us to propose an updated universal nomenclature for the fish ORs.展开更多
近年来,利用文本、视觉和音频数据分析视频中说话者情感的多模态情感分析(MSA)引起了广泛关注。然而,不同模态在情感分析中的贡献大不相同。通常,文本中包含的信息更加直观,因此寻求一种用于增强文本在情感分析中作用的策略显得尤为重...近年来,利用文本、视觉和音频数据分析视频中说话者情感的多模态情感分析(MSA)引起了广泛关注。然而,不同模态在情感分析中的贡献大不相同。通常,文本中包含的信息更加直观,因此寻求一种用于增强文本在情感分析中作用的策略显得尤为重要。针对这一问题,提出一种跨模态文本信息增强的多模态情感分析模型(MSAMCTE)。首先,使用BERT(Bidirectional Encoder Representations from Transformers)预训练模型提取文本特征,并使用双向长短期记忆(Bi-LSTM)网络对预处理后的音频和视频特征进行进一步处理;其次,通过基于文本的交叉注意力机制,将文本信息融入情感相关的非语言表示中,以学习面向文本的成对跨模态映射,从而获得有效的统一多模态表示;最后,使用融合特征进行情感分析。实验结果表明,与最优的基线模型——文本增强Transformer融合网络(TETFN)相比,MSAM-CTE在数据集CMU-MOSI(Carnegie Mellon University Multimodal Opinion Sentiment Intensity)上的平均绝对误差(MAE)和皮尔逊相关系数(Corr)分别降低了2.6%和提高了0.1%;在数据集CMU-MOSEI(Carnegie Mellon University Multimodal Opinion Sentiment and Emotion Intensity)上的两个指标分别降低了3.8%和提高了1.7%,验证了MSAM-CTE在情感分析中的有效性。展开更多
Effect of isothermal holding treatment in the solidification process on the microstructure of Ti-6Al-4V alloy was studied by temperature controlled induced melting apparatus. The result shows that with isothermal hold...Effect of isothermal holding treatment in the solidification process on the microstructure of Ti-6Al-4V alloy was studied by temperature controlled induced melting apparatus. The result shows that with isothermal holding treatment above the β transus temperature during solidification, the colony structure consisting of parallel lamellae was obtained. While the isothermal holding treatment was set at 960 °C, a unique bi-modal microstructure consisting of coarse primary α and fine secondary lamellar α was obtained. The primary lamellar α tended to break into several pieces, globularize and present equiaxed morphology. The formation mechanism of the equiaxed α can be explained with the atom immigration, high density dislocations, combined action with the interface tension of formed α phase during the isothermal holding treatment. After the isothermal holding, the retained β matrix transformed into fine lamellar α, thus, bi-modal microstructure was acquired. Compared with the lamellar structure, the grain boundary α presented discontinuously and cannot be distinguished from the primary α lamellae easily. The size of colonies α was greatly decreased. The microstructure tended to be much more homogeneous in the whole section of the samples.展开更多
基金Projects (50634060,50721003) supported by the National Natural Science Foundation of ChinaProject (2009AA03Z526) supported by the High-tech Research and Development Program of ChinaProject supported by the Open-End Fund for Valuable and Precision Instruments of Central South University
文摘Ferritic steel with a nominal composition of Fe-14Cr-3W-0.42Ti-0.32Y was prepared by mixing gas-atomized prealloyed powder and mechanically alloyed powder. The microstructure is much different fxom other ferritic steels with the same composition and prepared via only mechanically alloyed powder. A bi-modal structure, which consists of pure ferritic grains and martensitic grains, was obtained after hot forging and air cooling. A phase transformation of αbcc→γfcc→α＇bcc was also discovered in microstructural observation. The bi-modal microstructure shows a good combination of high strength and high ductility.
基金supported financially by the National Natural Science Foundation of China (Nos. 51671158 and 51621063)the National Program on Key Basic Research Project (No. 2014CB644003)the Programme of Introducing Talents of Discipline to Universities (No. PB2018008)。
文摘β titanium alloys with bi-modal structure which exhibit improved strength-ductility combination and fatigue property are widely used in aviation and aerospace industry.However,owing to the small size of primary α(αp) and nano-scaled multi variant distribution of secondary α platelets(αs),investigating the deformation behavior is really a challenging work.In this work,by applying transmission electron microscopy(TEM),the slip behavior in αp and transformed β matrix with different tensile strain was studied.After α/β solution treatment,the initial dislocation slips on {110} plane with <1 1 1> direction in β matrix.During furtherdeformation,(110),(101) and(1 1 2) multi slip is generated which shows a long straight cro s sing configuration.Dislocation cell is exhibited in β matrix at tensile strain above 20 %.Diffe rent from the solid solution treated sample,high density wavy dislocations are generated in transformedβ matrix.High fraction fine as hinders dislocation motion in β matrix effectively which in turn dominates the strength of the alloy.In primary α phase(αp),a core-shell structure is formed during deformation.Both pyramidal a+c slip and prismatic/basal a slip are generated in the shell layer.In core region,plastic deformation is governed by prismatic/basal a slip.Formation of the core-shell structure is the physical origin of the improved ductility.On one hand,the work hardening layer(shell) improves the strength of αp,which could deform compatibly with the hard transformed β matrix.Meanwhile,the center area(core) deforms homogeneously which will sustain plastic strain effectively and increase the ductility.This paper studies the slip behavior and reveals the origin of the improved strength-ductility combination in Bi-modal structure on a microscopic way,which will give theoretical advises for developing the next generation high strength β titanium alloys.
基金was supported by a PhD grant from "Fundagao para a Ciencia e a Tecnologia"(FCT)(L.S.:SFRH/BD/134565/2017,COVID/BD/151995/2021,T.M.:SFRH/BD/112458/2015supported by a PhD grant from“Fundação para a CiêL.R.:SFRH/BD/142322/2018)+3 种基金A.A.was partially supported by the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020 through national funds provided by FCT and the European Regional Development Fund(ERDF)in the framework of the program PT 2020the European Structural and Investment Funds(ESIF)through the Competitiveness and Internationalization Operational Program e COMPETE 2020 through the FCT project PTDC/CTA-AMB/31774/2017(POCI-01-0145-FEDER/031774/2017)the projects Ocean3R(NORTE-01-0145-FEDER-000064)Atlantida(NORTE-01-0145-FEDER-000040).
文摘Olfactory receptors(ORs)play a key role in the prime sensorial perception,being highly relevant for intra/interspecific interactions.ORs are a subgroup of G-protein coupled receptors that exhibit highly complex subgenomes in vertebrates.However,OR repertoires remain poorly studied in fish lineages,precluding finely retracing their origin,evolution,and diversification,especially in the most basal groups.Here,we conduct an exhaustive gene screening upon 43 high-quality fish genomes exhibiting varied gene repertoires(2e583 genes).While the early vertebrates performed gas exchange through gills,we hypothesize that the emergence of new breathing structures(swim bladder and paired lungs)in early osteichthyans may be associated with expansions in the ORs gene families sensitive to airborne molecules.Additionally,we verify that the OR repertoire of moderns actinopterygians has not increased as expected following a whole genome duplication,likely due to regulatory mechanisms compensating the gene load excess.Finally,we identify 25 distinct OR families,allowing us to propose an updated universal nomenclature for the fish ORs.
文摘近年来,利用文本、视觉和音频数据分析视频中说话者情感的多模态情感分析(MSA)引起了广泛关注。然而,不同模态在情感分析中的贡献大不相同。通常,文本中包含的信息更加直观,因此寻求一种用于增强文本在情感分析中作用的策略显得尤为重要。针对这一问题,提出一种跨模态文本信息增强的多模态情感分析模型(MSAMCTE)。首先,使用BERT(Bidirectional Encoder Representations from Transformers)预训练模型提取文本特征,并使用双向长短期记忆(Bi-LSTM)网络对预处理后的音频和视频特征进行进一步处理;其次,通过基于文本的交叉注意力机制,将文本信息融入情感相关的非语言表示中,以学习面向文本的成对跨模态映射,从而获得有效的统一多模态表示;最后,使用融合特征进行情感分析。实验结果表明,与最优的基线模型——文本增强Transformer融合网络(TETFN)相比,MSAM-CTE在数据集CMU-MOSI(Carnegie Mellon University Multimodal Opinion Sentiment Intensity)上的平均绝对误差(MAE)和皮尔逊相关系数(Corr)分别降低了2.6%和提高了0.1%;在数据集CMU-MOSEI(Carnegie Mellon University Multimodal Opinion Sentiment and Emotion Intensity)上的两个指标分别降低了3.8%和提高了1.7%,验证了MSAM-CTE在情感分析中的有效性。
基金Project(3102014JCQ01026)supported by the Fundamental Research Fund for the Central Universities,ChinaProject(B08040)supported by the Program of Introducing Talents of Discipline to Universities,China
文摘Effect of isothermal holding treatment in the solidification process on the microstructure of Ti-6Al-4V alloy was studied by temperature controlled induced melting apparatus. The result shows that with isothermal holding treatment above the β transus temperature during solidification, the colony structure consisting of parallel lamellae was obtained. While the isothermal holding treatment was set at 960 °C, a unique bi-modal microstructure consisting of coarse primary α and fine secondary lamellar α was obtained. The primary lamellar α tended to break into several pieces, globularize and present equiaxed morphology. The formation mechanism of the equiaxed α can be explained with the atom immigration, high density dislocations, combined action with the interface tension of formed α phase during the isothermal holding treatment. After the isothermal holding, the retained β matrix transformed into fine lamellar α, thus, bi-modal microstructure was acquired. Compared with the lamellar structure, the grain boundary α presented discontinuously and cannot be distinguished from the primary α lamellae easily. The size of colonies α was greatly decreased. The microstructure tended to be much more homogeneous in the whole section of the samples.
