Currently,conventional single-sided friction stir welding is primarily suitable for joining thin plate aluminum alloys,and its application to thick plates is still challenging in terms of welding efficiency and joint ...Currently,conventional single-sided friction stir welding is primarily suitable for joining thin plate aluminum alloys,and its application to thick plates is still challenging in terms of welding efficiency and joint mechanical properties.Simultaneous double-sided friction stir welding(SDS-FSW)is a high-efficiency joining technique specifically developed for welding thick plates.However,there is little research on the influence of SDS-FSW process parameters on the joint mechanical properties.In this study,a 12 mm thick AA6061-T6 aluminum alloy and dual robot welding equipment are used to conduct SDS-FSW experiments exploring the influence of rotational speedωand welding speed v on the mechanical properties and microstructure.The results show that when the welding parameters areω=800 r/min and v=60–80 mm/min,smooth and defect-free thick plate aluminum alloy SDS-FSW joints can be obtained,and the macroscopic morphology of the joints is distributed in a“dumbbell”shape.The grain size in the weld nugget zone increases with increasing welding heat input.The microhardness distribution in the joint displays a“W”shape,and the hardness value of the weld nugget zone can reach 67%to 86%of that of the base metal(BM).The junction between the thermo-mechanically affected zone and the heat affected zone is the weakest region of the joint,with the lowest hardness being approximately 51%of that of the BM.When the welding parameters areω=800 r/min and v=140 mm/min,the SDS-FSW joint has the highest tensile strength,reaching 78.43%of the BM strength and exhibiting ductile fracture characteristics.This research indicates that acceptable weld strength in thick aluminum alloys can be achieved via the SDS-FSW joining mechanism,highlighting its significant potential for industrial applications.展开更多
Blended acquisition offers efficiency improvements over conventional seismic data acquisition, at the cost of introducing blending noise effects. Besides, seismic data often suffers from irregularly missing shots caus...Blended acquisition offers efficiency improvements over conventional seismic data acquisition, at the cost of introducing blending noise effects. Besides, seismic data often suffers from irregularly missing shots caused by artificial or natural effects during blended acquisition. Therefore, blending noise attenuation and missing shots reconstruction are essential for providing high-quality seismic data for further seismic processing and interpretation. The iterative shrinkage thresholding algorithm can help obtain deblended data based on sparsity assumptions of complete unblended data, and it characterizes seismic data linearly. Supervised learning algorithms can effectively capture the nonlinear relationship between incomplete pseudo-deblended data and complete unblended data. However, the dependence on complete unblended labels limits their practicality in field applications. Consequently, a self-supervised algorithm is presented for simultaneous deblending and interpolation of incomplete blended data, which minimizes the difference between simulated and observed incomplete pseudo-deblended data. The used blind-trace U-Net (BTU-Net) prevents identity mapping during complete unblended data estimation. Furthermore, a multistep process with blending noise simulation-subtraction and missing traces reconstruction-insertion is used in each step to improve the deblending and interpolation performance. Experiments with synthetic and field incomplete blended data demonstrate the effectiveness of the multistep self-supervised BTU-Net algorithm.展开更多
The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence...The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.展开更多
The simultaneous removal of ethyl acetate, benzene and toluene with relatively low or high initial concentration is studied using a laboratory scale gliding arc gas discharge (GA) reactor. Good decomposition efficienc...The simultaneous removal of ethyl acetate, benzene and toluene with relatively low or high initial concentration is studied using a laboratory scale gliding arc gas discharge (GA) reactor. Good decomposition efficiencies are obtained which proves that the GA is effective for the treatment of volatile organic compounds (VOCs) with either low or high concentration. A theoretical decomposition mechanism is proposed based on detection of the species in the plasma region and analysis of the decomposition by-products. This preliminary investigation reveals that the GA has potential to be applied to the treatment of exhaust air during color printing and coating works, by either direct removal or combination with activated carbon adsorption/desorption process.展开更多
在动态场景下,视觉同时定位与地图构建(simultaneous localization and mapping, SLAM)通常与深度学习方法结合提高系统的定位精度.针对深度学习方法运行时产生的时间延迟,导致系统难以达到流式处理要求的问题,提出一种面向动态场景下视...在动态场景下,视觉同时定位与地图构建(simultaneous localization and mapping, SLAM)通常与深度学习方法结合提高系统的定位精度.针对深度学习方法运行时产生的时间延迟,导致系统难以达到流式处理要求的问题,提出一种面向动态场景下视觉SLAM的流感知定位方法.首先针对传统评估指标只考虑定位精度的问题,提出流式评估指标,该指标同时考虑定位精度和时间延迟,能够准确反映系统的流式处理性能;其次针对传统视觉SLAM方法无法实现流式处理的问题,提出流感知的视觉定位方法,通过多线程并行和相机位姿预测相结合的方式,获得持续稳定的相机位姿输出.在BONN数据集和真实场景上的实验结果表明,所提方法能够有效地提升动态场景下采用深度学习方法的视觉定位的流性能.基于BONN数据集和流式评估方式的评估结果表明,与DynaSLAM方法对比,所提方法的绝对轨迹误差(APE),相对平移误差(RPE_trans)和相对旋转误差(RPE_angle)分别下降80.438%, 56.180%和54.676%.在真实场景下的实验结果表明,所提方法可以得到与实际相符的相机轨迹.展开更多
在跨语言交流中,为了实现更加顺畅的无障碍交流,设计了基于大数据分析和语音识别的机器同步智能英语翻译系统。语音识别模块、翻译模块以及语音合成模块构成同步智能英语翻译系统,结合Mel频率倒谱系数(Mel Frequency Cepstrum Coefficie...在跨语言交流中,为了实现更加顺畅的无障碍交流,设计了基于大数据分析和语音识别的机器同步智能英语翻译系统。语音识别模块、翻译模块以及语音合成模块构成同步智能英语翻译系统,结合Mel频率倒谱系数(Mel Frequency Cepstrum Coefficient,MFCC)对语音数据信号进行特征提取,同时结合LSTM循环神经网络与词性向量进行语音翻译,以期使机器同步智能英语翻译系统快速准确地运行。经过实验验证,研究系统的匹配率平均达到94.7%,同时语言识别时间相较其他系统显著缩短,语音翻译及时高效。展开更多
Thermodynamic diagrams of Na−S−Fe−H_(2)O system were constructed to analyze the behavior of sulfur and iron in the Bayer process.After digestion,iron mainly exists as Fe_(3)O_(4) and Fe_(2)O_(3) in red mud,and partial...Thermodynamic diagrams of Na−S−Fe−H_(2)O system were constructed to analyze the behavior of sulfur and iron in the Bayer process.After digestion,iron mainly exists as Fe_(3)O_(4) and Fe_(2)O_(3) in red mud,and partial iron transfers into solution as Fe(OH)_(3)^(−),HFeO_(2)^(−),Fe(OH)_(4)^(−)and Fe(OH)_(4)^(2−).The dominant species of sulfur is S^(2−),followed by SO_(4)^(2−),and then SO_(3)^(2−)and S_(2)O_(3)^(2−).The thermodynamic analysis is consistent with the iron and sulfur species distribution in the solution obtained by experiments.When the temperature decreases,sulfur and iron can combine and precipitate.Controlling low potential and reducing temperature are beneficial to removing them from the solution.XRD patterns show that NaFeS_(2)·2H_(2)O,FeS and FeS_(2) widely appear in red mud and precipitates of pyrite and high-sulfur bauxite digestion solution.Thermodynamic analysis can be utilized to guide the simultaneous removal of sulfur and iron in the Bayer process.展开更多
The properties of matched streams, the simultaneous operation time, and the distance between integrated processes, are the main factors which determine whether the direct integration is feasible or not. According to w...The properties of matched streams, the simultaneous operation time, and the distance between integrated processes, are the main factors which determine whether the direct integration is feasible or not. According to whether such synthetic integration is economically better than the separate integration of each process, a mathematical formulation is established. The retrofit of reforming and arene processes in a certain petrochemical factory, which are independent each other, is chosen as a case study. By only considering the simultaneous operation time, two retrofit designs are proposed: one is that each of the two processes is separately integrated by itself, and the other is that the two processes are integrated comprehensively. Under different simultaneous operation hours, the energy-saving effects and the economic profits of the two designs are calculated, and furthermore, the critical simultaneous operation time for direct heat integration of the two processes is obtained. When the actual simultaneous operation time of the two processes is longer than the critical value, the direct heat integration of the two processes is better economically, and otherwise the separate heat integration for each process should be considered.展开更多
The human motion generation model can extract structural features from existing human motion capture data,and the generated data makes animated characters move.The 3D human motion capture sequences contain complex spa...The human motion generation model can extract structural features from existing human motion capture data,and the generated data makes animated characters move.The 3D human motion capture sequences contain complex spatial-temporal structures,and the deep learning model can fully describe the potential semantic structure of human motion.To improve the authenticity of the generated human motion sequences,we propose a multi-task motion generation model that consists of a discriminator and a generator.The discriminator classifies motion sequences into different styles according to their similarity to the mean spatial-temporal templates from motion sequences of 17 crucial human joints in three-freedom degrees.And target motion sequences are created with these styles by the generator.Unlike traditional related works,our model can handle multiple tasks,such as identifying styles and generating data.In addition,by extracting 17 crucial joints from 29 human joints,our model avoids data redundancy and improves the accuracy of model recognition.The experimental results show that the discriminator of the model can effectively recognize diversified movements,and the generated data can correctly fit the actual data.The combination of discriminator and generator solves the problem of low reuse rate of motion data,and the generated motion sequences are more suitable for actual movement.展开更多
基金Supported by National Key R&D program of China(Grant No.2019YFA0709004)。
文摘Currently,conventional single-sided friction stir welding is primarily suitable for joining thin plate aluminum alloys,and its application to thick plates is still challenging in terms of welding efficiency and joint mechanical properties.Simultaneous double-sided friction stir welding(SDS-FSW)is a high-efficiency joining technique specifically developed for welding thick plates.However,there is little research on the influence of SDS-FSW process parameters on the joint mechanical properties.In this study,a 12 mm thick AA6061-T6 aluminum alloy and dual robot welding equipment are used to conduct SDS-FSW experiments exploring the influence of rotational speedωand welding speed v on the mechanical properties and microstructure.The results show that when the welding parameters areω=800 r/min and v=60–80 mm/min,smooth and defect-free thick plate aluminum alloy SDS-FSW joints can be obtained,and the macroscopic morphology of the joints is distributed in a“dumbbell”shape.The grain size in the weld nugget zone increases with increasing welding heat input.The microhardness distribution in the joint displays a“W”shape,and the hardness value of the weld nugget zone can reach 67%to 86%of that of the base metal(BM).The junction between the thermo-mechanically affected zone and the heat affected zone is the weakest region of the joint,with the lowest hardness being approximately 51%of that of the BM.When the welding parameters areω=800 r/min and v=140 mm/min,the SDS-FSW joint has the highest tensile strength,reaching 78.43%of the BM strength and exhibiting ductile fracture characteristics.This research indicates that acceptable weld strength in thick aluminum alloys can be achieved via the SDS-FSW joining mechanism,highlighting its significant potential for industrial applications.
基金supported by the National Natural Science Foundation of China(42374134,42304125,U20B6005)the Science and Technology Commission of Shanghai Municipality(23JC1400502)the Fundamental Research Funds for the Central Universities.
文摘Blended acquisition offers efficiency improvements over conventional seismic data acquisition, at the cost of introducing blending noise effects. Besides, seismic data often suffers from irregularly missing shots caused by artificial or natural effects during blended acquisition. Therefore, blending noise attenuation and missing shots reconstruction are essential for providing high-quality seismic data for further seismic processing and interpretation. The iterative shrinkage thresholding algorithm can help obtain deblended data based on sparsity assumptions of complete unblended data, and it characterizes seismic data linearly. Supervised learning algorithms can effectively capture the nonlinear relationship between incomplete pseudo-deblended data and complete unblended data. However, the dependence on complete unblended labels limits their practicality in field applications. Consequently, a self-supervised algorithm is presented for simultaneous deblending and interpolation of incomplete blended data, which minimizes the difference between simulated and observed incomplete pseudo-deblended data. The used blind-trace U-Net (BTU-Net) prevents identity mapping during complete unblended data estimation. Furthermore, a multistep process with blending noise simulation-subtraction and missing traces reconstruction-insertion is used in each step to improve the deblending and interpolation performance. Experiments with synthetic and field incomplete blended data demonstrate the effectiveness of the multistep self-supervised BTU-Net algorithm.
基金Project supported by the Key International Cooperative Program of NSFC(No. 50521140075)the Hi-Tech Research and Development Program(863)of China(No. 2004AA601020)the Attached Projects of"863"Project of Beijing Municipal Science and Technology(No.20005186040421).
文摘The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.
基金Project (No. 50476058) supported by the National Natural ScienceFoundation of China
文摘The simultaneous removal of ethyl acetate, benzene and toluene with relatively low or high initial concentration is studied using a laboratory scale gliding arc gas discharge (GA) reactor. Good decomposition efficiencies are obtained which proves that the GA is effective for the treatment of volatile organic compounds (VOCs) with either low or high concentration. A theoretical decomposition mechanism is proposed based on detection of the species in the plasma region and analysis of the decomposition by-products. This preliminary investigation reveals that the GA has potential to be applied to the treatment of exhaust air during color printing and coating works, by either direct removal or combination with activated carbon adsorption/desorption process.
文摘在跨语言交流中,为了实现更加顺畅的无障碍交流,设计了基于大数据分析和语音识别的机器同步智能英语翻译系统。语音识别模块、翻译模块以及语音合成模块构成同步智能英语翻译系统,结合Mel频率倒谱系数(Mel Frequency Cepstrum Coefficient,MFCC)对语音数据信号进行特征提取,同时结合LSTM循环神经网络与词性向量进行语音翻译,以期使机器同步智能英语翻译系统快速准确地运行。经过实验验证,研究系统的匹配率平均达到94.7%,同时语言识别时间相较其他系统显著缩短,语音翻译及时高效。
基金the financial supports from the National Natural Science Foundation of China(No.51904052)the Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2020jcyjmsxm X0476)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission,China(No.KJQN201901508)the Graduate Science and Technology Innovation Training Program of Chongqing University of Science and Technology,China(No.YKJCX2020201)。
文摘Thermodynamic diagrams of Na−S−Fe−H_(2)O system were constructed to analyze the behavior of sulfur and iron in the Bayer process.After digestion,iron mainly exists as Fe_(3)O_(4) and Fe_(2)O_(3) in red mud,and partial iron transfers into solution as Fe(OH)_(3)^(−),HFeO_(2)^(−),Fe(OH)_(4)^(−)and Fe(OH)_(4)^(2−).The dominant species of sulfur is S^(2−),followed by SO_(4)^(2−),and then SO_(3)^(2−)and S_(2)O_(3)^(2−).The thermodynamic analysis is consistent with the iron and sulfur species distribution in the solution obtained by experiments.When the temperature decreases,sulfur and iron can combine and precipitate.Controlling low potential and reducing temperature are beneficial to removing them from the solution.XRD patterns show that NaFeS_(2)·2H_(2)O,FeS and FeS_(2) widely appear in red mud and precipitates of pyrite and high-sulfur bauxite digestion solution.Thermodynamic analysis can be utilized to guide the simultaneous removal of sulfur and iron in the Bayer process.
基金Supported by the National Natural Science Foundation of China(No. 20176045)Major State Basic Research Development Program of China(No. G20000263)
文摘The properties of matched streams, the simultaneous operation time, and the distance between integrated processes, are the main factors which determine whether the direct integration is feasible or not. According to whether such synthetic integration is economically better than the separate integration of each process, a mathematical formulation is established. The retrofit of reforming and arene processes in a certain petrochemical factory, which are independent each other, is chosen as a case study. By only considering the simultaneous operation time, two retrofit designs are proposed: one is that each of the two processes is separately integrated by itself, and the other is that the two processes are integrated comprehensively. Under different simultaneous operation hours, the energy-saving effects and the economic profits of the two designs are calculated, and furthermore, the critical simultaneous operation time for direct heat integration of the two processes is obtained. When the actual simultaneous operation time of the two processes is longer than the critical value, the direct heat integration of the two processes is better economically, and otherwise the separate heat integration for each process should be considered.
文摘The human motion generation model can extract structural features from existing human motion capture data,and the generated data makes animated characters move.The 3D human motion capture sequences contain complex spatial-temporal structures,and the deep learning model can fully describe the potential semantic structure of human motion.To improve the authenticity of the generated human motion sequences,we propose a multi-task motion generation model that consists of a discriminator and a generator.The discriminator classifies motion sequences into different styles according to their similarity to the mean spatial-temporal templates from motion sequences of 17 crucial human joints in three-freedom degrees.And target motion sequences are created with these styles by the generator.Unlike traditional related works,our model can handle multiple tasks,such as identifying styles and generating data.In addition,by extracting 17 crucial joints from 29 human joints,our model avoids data redundancy and improves the accuracy of model recognition.The experimental results show that the discriminator of the model can effectively recognize diversified movements,and the generated data can correctly fit the actual data.The combination of discriminator and generator solves the problem of low reuse rate of motion data,and the generated motion sequences are more suitable for actual movement.
