Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other...Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.展开更多
自动化检测需求实体共指(EC),对于需求质量的一致性分析十分重要。现有方法往往是利用编辑距离或词嵌入等完成EC检测,其在没有大量专家标注数据的情况下和在捕获需求语句较为复杂的语义信息方面表现不佳。提出一种用于EC检测的新型深度...自动化检测需求实体共指(EC),对于需求质量的一致性分析十分重要。现有方法往往是利用编辑距离或词嵌入等完成EC检测,其在没有大量专家标注数据的情况下和在捕获需求语句较为复杂的语义信息方面表现不佳。提出一种用于EC检测的新型深度网络DeepCorp(Deep&Context-wise&Requirements Operation Role Network),通过引入实体上下文和需求操作角色信息,使用多层感知机隐式融合嵌入表示来实现需求实体深层次的语义表达,从而进行实体语义相似性判断。在公开需求文档仓库上的实验表明,DeepCorp可达到96.72%准确率、96.67%召回率和96.69%F1,相较于现有方法平均提升1.27%。展开更多
The fifth-generation (5G) communication requires a highly accurate estimation of the channel state information (CSI)to take advantage of the massive multiple-input multiple-output(MIMO) system. However, traditional ch...The fifth-generation (5G) communication requires a highly accurate estimation of the channel state information (CSI)to take advantage of the massive multiple-input multiple-output(MIMO) system. However, traditional channel estimation methods do not always yield reliable estimates. The methodology of this paper consists of deep residual shrinkage network (DRSN)neural network-based method that is used to solve this problem.Thus, the channel estimation approach, based on DRSN with its learning ability of noise-containing data, is first introduced. Then,the DRSN is used to train the noise reduction process based on the results of the least square (LS) channel estimation while applying the pilot frequency subcarriers, where the initially estimated subcarrier channel matrix is considered as a three-dimensional tensor of the DRSN input. Afterward, a mixed signal to noise ratio (SNR) training data strategy is proposed based on the learning ability of DRSN under different SNRs. Moreover, a joint mixed scenario training strategy is carried out to test the multi scenarios robustness of DRSN. As for the findings, the numerical results indicate that the DRSN method outperforms the spatial-frequency-temporal convolutional neural networks (SF-CNN)with similar computational complexity and achieves better advantages in the full SNR range than the minimum mean squared error (MMSE) estimator with a limited dataset. Moreover, the DRSN approach shows robustness in different propagation environments.展开更多
The evolution of cracks in shale directly affects the efficient production of shale gas.However,there is a lack of research on the characteristics of crack initiation in deep dense shale under different stress conditi...The evolution of cracks in shale directly affects the efficient production of shale gas.However,there is a lack of research on the characteristics of crack initiation in deep dense shale under different stress conditions.In this work,considering the different combinations of confining pressure and bedding plane inclination angle(α),biaxial mechanical loading experiments were conducted on shale containing circular holes.The research results indicate that the confining pressure and inclination angle of the bedding planes significantly influence the failure patterns of shale containing circular holes.The instability of shale containing circular holes can be classified into five types:tensile failure along the bedding planes,tensile failure through the bedding planes,shear slip along the bedding planes,shear failure through the bedding planes,and block instability failure.Furthermore,the evolution of strain and stress fields around the circular holes was found to be the fundamental cause of variations in the initiation characteristics and locations of shale cracks.The crack initiation criterion for shale containing circular hole was established,providing a new method for evaluating the trajectory of shale hole wall fractures.This study holds significant importance for evaluating the evolution and stability of fracture networks within shale reservoirs.展开更多
In the present study,two-layered stainless steel-copper composites with a thickness of 50μm were initially subjected to annealing at 800,900 and 1000℃for 5 min,respectively,to achieve diverse microstructural feature...In the present study,two-layered stainless steel-copper composites with a thickness of 50μm were initially subjected to annealing at 800,900 and 1000℃for 5 min,respectively,to achieve diverse microstructural features.Then the influence of annealing temperature on the formability of stainless steel-copper composites and the quality of micro composite cups manufactured by micro deep drawing(MDD)were investigated,and the underlying mechanism was analyzed.Three finite element(FE)models,including basic FE model,Voronoi FE model and surface morphological FE model,were developed to analyze the forming performance of stainless steel-copper composites during MDD.The results show that the stainless steel-copper composites annealed at 900℃possess the best plasticity owing to the homogeneous and refined microstructure in both stainless steel and copper matrixes,and the micro composite cup with specimen annealed at 900℃exhibits a uniform wall thickness as well as high surface quality with the fewest wrinkles.The results obtained from the surface morphological FE model considering material inhomogeneity and surface morphology of the composites are the closest to the experimental results compared to the basic and Voronoi FE model.During MDD process,the drawing forces decrease with increasing annealing temperature as a consequence of the strength reduction.展开更多
基金financially supported by the Key Research and Development Program of Ningbo(Grant No.2023Z098)Natural Science Foundation of Inner Mongolia(Grant No.2023MS05040)+1 种基金Shenyang Collaborative Innovation Center Project for Multiple Energy Fields Composite Processing of Special Materials(Grant No.JG210027)Shenyang Key Technology Special Project of The Open Competition Mechanism to Select the Best Solution(Grant Nos.2022210101000827,2022-0-43-048).
文摘Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.
文摘自动化检测需求实体共指(EC),对于需求质量的一致性分析十分重要。现有方法往往是利用编辑距离或词嵌入等完成EC检测,其在没有大量专家标注数据的情况下和在捕获需求语句较为复杂的语义信息方面表现不佳。提出一种用于EC检测的新型深度网络DeepCorp(Deep&Context-wise&Requirements Operation Role Network),通过引入实体上下文和需求操作角色信息,使用多层感知机隐式融合嵌入表示来实现需求实体深层次的语义表达,从而进行实体语义相似性判断。在公开需求文档仓库上的实验表明,DeepCorp可达到96.72%准确率、96.67%召回率和96.69%F1,相较于现有方法平均提升1.27%。
基金supported by the National Key Scientific Instrument and Equipment Development Project(61827801).
文摘The fifth-generation (5G) communication requires a highly accurate estimation of the channel state information (CSI)to take advantage of the massive multiple-input multiple-output(MIMO) system. However, traditional channel estimation methods do not always yield reliable estimates. The methodology of this paper consists of deep residual shrinkage network (DRSN)neural network-based method that is used to solve this problem.Thus, the channel estimation approach, based on DRSN with its learning ability of noise-containing data, is first introduced. Then,the DRSN is used to train the noise reduction process based on the results of the least square (LS) channel estimation while applying the pilot frequency subcarriers, where the initially estimated subcarrier channel matrix is considered as a three-dimensional tensor of the DRSN input. Afterward, a mixed signal to noise ratio (SNR) training data strategy is proposed based on the learning ability of DRSN under different SNRs. Moreover, a joint mixed scenario training strategy is carried out to test the multi scenarios robustness of DRSN. As for the findings, the numerical results indicate that the DRSN method outperforms the spatial-frequency-temporal convolutional neural networks (SF-CNN)with similar computational complexity and achieves better advantages in the full SNR range than the minimum mean squared error (MMSE) estimator with a limited dataset. Moreover, the DRSN approach shows robustness in different propagation environments.
基金Projects(52104143,52109135,52374099)supported by the National Natural Science Foundation of ChinaProject(2025YFHZ0323)supported by the Natural Science Foundation of Sichuan Province,China。
文摘The evolution of cracks in shale directly affects the efficient production of shale gas.However,there is a lack of research on the characteristics of crack initiation in deep dense shale under different stress conditions.In this work,considering the different combinations of confining pressure and bedding plane inclination angle(α),biaxial mechanical loading experiments were conducted on shale containing circular holes.The research results indicate that the confining pressure and inclination angle of the bedding planes significantly influence the failure patterns of shale containing circular holes.The instability of shale containing circular holes can be classified into five types:tensile failure along the bedding planes,tensile failure through the bedding planes,shear slip along the bedding planes,shear failure through the bedding planes,and block instability failure.Furthermore,the evolution of strain and stress fields around the circular holes was found to be the fundamental cause of variations in the initiation characteristics and locations of shale cracks.The crack initiation criterion for shale containing circular hole was established,providing a new method for evaluating the trajectory of shale hole wall fractures.This study holds significant importance for evaluating the evolution and stability of fracture networks within shale reservoirs.
基金Projects(51975398,52105392)supported by the National Natural Science Foundation of ChinaProject(YDZJSX2021A006)supported by the Central Government Guided Local Science and Technology Development Fund Project,China+1 种基金Project(20210035)supported by the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province,ChinaProject(2020-037)supported by the Fund Program for the Research Project Supported by Shanxi Scholarship Council,China。
文摘In the present study,two-layered stainless steel-copper composites with a thickness of 50μm were initially subjected to annealing at 800,900 and 1000℃for 5 min,respectively,to achieve diverse microstructural features.Then the influence of annealing temperature on the formability of stainless steel-copper composites and the quality of micro composite cups manufactured by micro deep drawing(MDD)were investigated,and the underlying mechanism was analyzed.Three finite element(FE)models,including basic FE model,Voronoi FE model and surface morphological FE model,were developed to analyze the forming performance of stainless steel-copper composites during MDD.The results show that the stainless steel-copper composites annealed at 900℃possess the best plasticity owing to the homogeneous and refined microstructure in both stainless steel and copper matrixes,and the micro composite cup with specimen annealed at 900℃exhibits a uniform wall thickness as well as high surface quality with the fewest wrinkles.The results obtained from the surface morphological FE model considering material inhomogeneity and surface morphology of the composites are the closest to the experimental results compared to the basic and Voronoi FE model.During MDD process,the drawing forces decrease with increasing annealing temperature as a consequence of the strength reduction.
