Based on the finite element method(FEM)in the frequency domain and particle-in-cell approach in the time domain,a hybrid domain multipactor threshold prediction algorithm is proposed in this paper.The proposed algorit...Based on the finite element method(FEM)in the frequency domain and particle-in-cell approach in the time domain,a hybrid domain multipactor threshold prediction algorithm is proposed in this paper.The proposed algorithm has the advantages of the frequency domain and the time domain algorithms at the same time in terms of high computational accuracy and considerable computational efficiency.In addition,the compute unified device architecture(CUDA)acceleration technique also can be employed to further enhance its simulation efficiency.Numerical examples are carried out to demonstrate the effectiveness of the proposed algorithm.The results indicate that the multipactor threshold can be accurately predicted and the computational efficiency can be improved.展开更多
The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenar...The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenarios, however, needs to be quantitatively evaluated. In this study, four compensation methods （i.e., the polynomial extrapolation, the linear acceleration extrapolation, the inverse compensation and the adaptive inverse compensation） are selected and compared experimentally using a frequency evaluation index （FEI） method. The effectiveness of the FEI method is first verified through comparison with the discrete transfer fimction approach for compensation methods assuming constant delay. Incomparable advantage is further demonstrated for the FEI method when applied to adaptive compensation methods, where the discrete transfer function approach is difficult to implement. Both numerical simulation and laboratory tests with predefined displacements are conducted using sinusoidal signals and random signals as inputs. Findings from numerical simulation and experimental results demonstrate that the FEI method is an efficient and effective approach to compare the performance of different compensation methods, especially for those requiring adaptation of compensation parameters.展开更多
An online hybrid test was carried out on a 40-story 120-m high concrete shear wall structure. The structure was divided into two substructures whereby a physical model of the bottom three stories was tested in the lab...An online hybrid test was carried out on a 40-story 120-m high concrete shear wall structure. The structure was divided into two substructures whereby a physical model of the bottom three stories was tested in the laboratory and the upper 37 stories were simulated numerically using ABAQUS. An overlapping domain method was employed for the bottom three stories to ensure the validity of the boundary conditions of the superstructure. Mixed control was adopted in the test. Displacement control was used to apply the horizontal displacement, while two controlled force actuators were applied to simulate the overturning moment, which is very large and cannot be ignored in the substructure hybrid test of high-rise buildings. A series of tests with earthquake sources of sequentially increasing intensities were carried out. The test results indicate that the proposed hybrid test method is a solution to reproduce the seismic response of high-rise concrete shear wall buildings. The seismic performance of the tested precast high-rise building satisfies the requirements of the Chinese seismic design code.展开更多
This paper studies a bounded discriminating domain for hybrid linear differential game with two players and two targets using viability theory. First of all, we prove that the convex hull of a closed set is also a dis...This paper studies a bounded discriminating domain for hybrid linear differential game with two players and two targets using viability theory. First of all, we prove that the convex hull of a closed set is also a discriminating domain if the set is a discriminating domain. Secondly, in order to determine that a bounded polyhedron is a discriminating domain, we give a result that it only needs to verify that the extreme points of the polyhedron meet the viability conditions. The difference between our result and the existing ones is that our result just needs to verify the finite points （extreme points） and the existing ones need to verify all points in the bounded polyhedron.展开更多
Eariy-arrival waveform tomography （EWT） is one of the most promising techniques for building near-surface velocity model. Based on finite-frequency wave equation, EWT estimates velocities by matching calculated earl...Eariy-arrival waveform tomography （EWT） is one of the most promising techniques for building near-surface velocity model. Based on finite-frequency wave equation, EWT estimates velocities by matching calculated early-arrival waveforms with the observed ones. However, the objective function of EWT can easily converge to local minimum because of the cycle-skipping phenomenon. In order to reduce the cycle-skipping problem, a hybrid-domain early-arrival waveform tomography （HEWT） is proposed in this paper. The forward modeling of HEWT is realized in the time domain where early-arrival waveforms are easier to be selected from seismic data and less memory is needed than they are in the frequency domain. The inversion is implemented in the frequency domain where multi-scale strategy is more convenient to be realized than that in the time domain. Discrete Fourier transformation （DFT） is used to transform the time-domain wavefield to the frequency-domain wavefield. Test results show that HEWT is more competitive than EWT in both accuracy and computational time.展开更多
On the basis of composition duality principles, augmented three-field macrohybrid mixed variational problems and finite element schemes are analyzed. The compatibility condition adopted here, for compositional dualiza...On the basis of composition duality principles, augmented three-field macrohybrid mixed variational problems and finite element schemes are analyzed. The compatibility condition adopted here, for compositional dualization, is the coupling operator surjectivity, property that expresses in a general operator sense the Ladysenskaja-Babulka-Brezzi inf-sup condition. Variational macro-hybridization is performed under the assumption of decomposable primal and dual spaces relative to nonoverlapping domain decompositions. Then, through compositional dualization macro-hybrid mixed problems are obtained, with internal boundary dual traces as Lagrange multipliers. Also, ＂mass＂ preconditioned aug- mentation of three-field formulations are derived, stabilizing macro-hybrid mixed finite element schemes and rendering possible speed up of rates of convergence. Dual mixed incompressible Darcy flow problems illustrate the theory throughout the paper.展开更多
Plant cellulose synthases (CesAs) are the key enzymes necessary for cellulose biosynthesis. In Arabidopsis, two distinct groups of three CesAs each are necessary for cellulose synthesis during primary and secondary ce...Plant cellulose synthases (CesAs) are the key enzymes necessary for cellulose biosynthesis. In Arabidopsis, two distinct groups of three CesAs each are necessary for cellulose synthesis during primary and secondary cell wall formation. It has also been suggested that such three CesAs interact with each other to form plasma-membrane bound rosette complexes that are functional during cellulose production. However, in vivo demonstration of such assemblies of three CesAs into rosettes has not been possible. We used yeast two-hybrid assays to demonstrate the possible interactions among several CesAs from Arabidopsis and aspen via their N-terminal zinc-binding domains (ZnBDs). While strong positive interactions were detected among ZnBDs from secondary wall associated CesAs of both Arabidopsis and aspen, the intergeneric interactions between Arabidopsis and aspen CesAs were weak. Moreover, in aspen, three primary wall associated CesA ZnBDs positively interacted with each other as well as with secondary CesAs. These results suggest that ZnBDs from either primary or secondary CesAs, and even from different plant species could interact but are perhaps insufficient for specificities of such interactions among CesAs. These observations suggest that some other more specific interacting regions might exist within CesAs. It is also possible that some hitherto unknown mechanism exists in plants for assembling the rosette complexes with different compositions of CesAs. Understanding how cellulose is synthesized will have a direct impact on utilization of lignocellulosic biomass for bioenergy production.展开更多
This paper proposes a hybrid full-wave analysis using Finite-Difference Time-Domain (FDTD) and Wave Concept Iterative Process (WCIP) methods, developed to analyze locally arbitrarily shaped microwave structures and Mu...This paper proposes a hybrid full-wave analysis using Finite-Difference Time-Domain (FDTD) and Wave Concept Iterative Process (WCIP) methods, developed to analyze locally arbitrarily shaped microwave structures and Multilayer Planar structure. Using the equivalence principle, the original problem can be decomposed into two sub regions and solve each sub region separately. An interpolation scheme is proposed for communicating between the FDTD fields and WCIP wave, which will not require the effort of fitting the WCIP mesh to the FDTD cells in the interface region. This method is applied to calculate the scattering parameters of arbitrary (3-D) microwave structures. Applying FDTD to 3D discontinuity and WCIP to the remaining region preserves the advantages of both WCIP flexibility and FDTD efficiency. A comparison of the results with the FDTD staircasing data verifies the accuracy of the proposed method.展开更多
针对目前基于检索增强生成技术的领域问答任务中由于用户查询和知识库中相关知识的语义差距导致回答效果差的问题,本文提出一种基于关键词抽取和混合检索的对齐优化方法。首先,利用大语言模型抽取用户查询中的关键词;其次,将用户查询拼...针对目前基于检索增强生成技术的领域问答任务中由于用户查询和知识库中相关知识的语义差距导致回答效果差的问题,本文提出一种基于关键词抽取和混合检索的对齐优化方法。首先,利用大语言模型抽取用户查询中的关键词;其次,将用户查询拼接抽取后的关键词组成组合查询,将组合查询与用户查询分别输入稀疏检索模型和稠密检索模型召回相关文档;然后,将检索模型召回的文档做并集处理并重排;最后,将重排后的相关知识输入文本过滤器提取出关键信息文本,并与用户查询合并输入大语言模型生成答案返回给用户。实验结果表明,所提方法在公开的中医药问答数据集和通用领域问答数据集CMRC2018上相较于基于查询改写的对齐优化方法,Recall-Oriented Understudy for Gisting Evaluation Longest common subsequence(ROUGE-L)指标分别提高了9.9个百分点和2.3个百分点,F1指标分别提高了4.1个百分点和1.7个百分点。本文的实验结果验证了所提方法在提升领域问答准确度的有效性。展开更多
基金This work was supported by the National Natural Science Foundation of China(61571022,61971022)the National Key laboratory Foundation(HTKJ2019KI504013,61424020305).
文摘Based on the finite element method(FEM)in the frequency domain and particle-in-cell approach in the time domain,a hybrid domain multipactor threshold prediction algorithm is proposed in this paper.The proposed algorithm has the advantages of the frequency domain and the time domain algorithms at the same time in terms of high computational accuracy and considerable computational efficiency.In addition,the compute unified device architecture(CUDA)acceleration technique also can be employed to further enhance its simulation efficiency.Numerical examples are carried out to demonstrate the effectiveness of the proposed algorithm.The results indicate that the multipactor threshold can be accurately predicted and the computational efficiency can be improved.
基金National Natural Science Foundation of China under Grant No.51378107the Fundamental Research Funds for the Central Universities and Priority Academic Program Development of Jiangsu Higher Education Institutions under Grant No.KYLX-0158the National Natural Science Foundation under Grant No.CMMI-1227962
文摘The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenarios, however, needs to be quantitatively evaluated. In this study, four compensation methods （i.e., the polynomial extrapolation, the linear acceleration extrapolation, the inverse compensation and the adaptive inverse compensation） are selected and compared experimentally using a frequency evaluation index （FEI） method. The effectiveness of the FEI method is first verified through comparison with the discrete transfer fimction approach for compensation methods assuming constant delay. Incomparable advantage is further demonstrated for the FEI method when applied to adaptive compensation methods, where the discrete transfer function approach is difficult to implement. Both numerical simulation and laboratory tests with predefined displacements are conducted using sinusoidal signals and random signals as inputs. Findings from numerical simulation and experimental results demonstrate that the FEI method is an efficient and effective approach to compare the performance of different compensation methods, especially for those requiring adaptation of compensation parameters.
基金State Key Research Project in 13th Five-Year under Grant No.2016YFC0701901the Beijing Science and Technology Program under Grant No.Z161100001216015the Natural Science Foundation of China under Grants Nos.51422809 and 51778342
文摘An online hybrid test was carried out on a 40-story 120-m high concrete shear wall structure. The structure was divided into two substructures whereby a physical model of the bottom three stories was tested in the laboratory and the upper 37 stories were simulated numerically using ABAQUS. An overlapping domain method was employed for the bottom three stories to ensure the validity of the boundary conditions of the superstructure. Mixed control was adopted in the test. Displacement control was used to apply the horizontal displacement, while two controlled force actuators were applied to simulate the overturning moment, which is very large and cannot be ignored in the substructure hybrid test of high-rise buildings. A series of tests with earthquake sources of sequentially increasing intensities were carried out. The test results indicate that the proposed hybrid test method is a solution to reproduce the seismic response of high-rise concrete shear wall buildings. The seismic performance of the tested precast high-rise building satisfies the requirements of the Chinese seismic design code.
基金supported by National Science Foundation of China(11171221)Doctoral Program Foundation of Institutions of Higher Education of China(20123120110004)+2 种基金Natural Science Foundation of Shanghai(14ZR1429200)Innovation Program of Shanghai Municipal Education Commission(15ZZ073)Key Research Project Plan of Institutions of Higher of Henan Province(17A120010)
文摘This paper studies a bounded discriminating domain for hybrid linear differential game with two players and two targets using viability theory. First of all, we prove that the convex hull of a closed set is also a discriminating domain if the set is a discriminating domain. Secondly, in order to determine that a bounded polyhedron is a discriminating domain, we give a result that it only needs to verify that the extreme points of the polyhedron meet the viability conditions. The difference between our result and the existing ones is that our result just needs to verify the finite points （extreme points） and the existing ones need to verify all points in the bounded polyhedron.
基金supported by the National Natural Science Foundation of China (Nos. 41230138, 41074077)
文摘Eariy-arrival waveform tomography （EWT） is one of the most promising techniques for building near-surface velocity model. Based on finite-frequency wave equation, EWT estimates velocities by matching calculated early-arrival waveforms with the observed ones. However, the objective function of EWT can easily converge to local minimum because of the cycle-skipping phenomenon. In order to reduce the cycle-skipping problem, a hybrid-domain early-arrival waveform tomography （HEWT） is proposed in this paper. The forward modeling of HEWT is realized in the time domain where early-arrival waveforms are easier to be selected from seismic data and less memory is needed than they are in the frequency domain. The inversion is implemented in the frequency domain where multi-scale strategy is more convenient to be realized than that in the time domain. Discrete Fourier transformation （DFT） is used to transform the time-domain wavefield to the frequency-domain wavefield. Test results show that HEWT is more competitive than EWT in both accuracy and computational time.
文摘On the basis of composition duality principles, augmented three-field macrohybrid mixed variational problems and finite element schemes are analyzed. The compatibility condition adopted here, for compositional dualization, is the coupling operator surjectivity, property that expresses in a general operator sense the Ladysenskaja-Babulka-Brezzi inf-sup condition. Variational macro-hybridization is performed under the assumption of decomposable primal and dual spaces relative to nonoverlapping domain decompositions. Then, through compositional dualization macro-hybrid mixed problems are obtained, with internal boundary dual traces as Lagrange multipliers. Also, ＂mass＂ preconditioned aug- mentation of three-field formulations are derived, stabilizing macro-hybrid mixed finite element schemes and rendering possible speed up of rates of convergence. Dual mixed incompressible Darcy flow problems illustrate the theory throughout the paper.
文摘Plant cellulose synthases (CesAs) are the key enzymes necessary for cellulose biosynthesis. In Arabidopsis, two distinct groups of three CesAs each are necessary for cellulose synthesis during primary and secondary cell wall formation. It has also been suggested that such three CesAs interact with each other to form plasma-membrane bound rosette complexes that are functional during cellulose production. However, in vivo demonstration of such assemblies of three CesAs into rosettes has not been possible. We used yeast two-hybrid assays to demonstrate the possible interactions among several CesAs from Arabidopsis and aspen via their N-terminal zinc-binding domains (ZnBDs). While strong positive interactions were detected among ZnBDs from secondary wall associated CesAs of both Arabidopsis and aspen, the intergeneric interactions between Arabidopsis and aspen CesAs were weak. Moreover, in aspen, three primary wall associated CesA ZnBDs positively interacted with each other as well as with secondary CesAs. These results suggest that ZnBDs from either primary or secondary CesAs, and even from different plant species could interact but are perhaps insufficient for specificities of such interactions among CesAs. These observations suggest that some other more specific interacting regions might exist within CesAs. It is also possible that some hitherto unknown mechanism exists in plants for assembling the rosette complexes with different compositions of CesAs. Understanding how cellulose is synthesized will have a direct impact on utilization of lignocellulosic biomass for bioenergy production.
文摘This paper proposes a hybrid full-wave analysis using Finite-Difference Time-Domain (FDTD) and Wave Concept Iterative Process (WCIP) methods, developed to analyze locally arbitrarily shaped microwave structures and Multilayer Planar structure. Using the equivalence principle, the original problem can be decomposed into two sub regions and solve each sub region separately. An interpolation scheme is proposed for communicating between the FDTD fields and WCIP wave, which will not require the effort of fitting the WCIP mesh to the FDTD cells in the interface region. This method is applied to calculate the scattering parameters of arbitrary (3-D) microwave structures. Applying FDTD to 3D discontinuity and WCIP to the remaining region preserves the advantages of both WCIP flexibility and FDTD efficiency. A comparison of the results with the FDTD staircasing data verifies the accuracy of the proposed method.
文摘针对目前基于检索增强生成技术的领域问答任务中由于用户查询和知识库中相关知识的语义差距导致回答效果差的问题,本文提出一种基于关键词抽取和混合检索的对齐优化方法。首先,利用大语言模型抽取用户查询中的关键词;其次,将用户查询拼接抽取后的关键词组成组合查询,将组合查询与用户查询分别输入稀疏检索模型和稠密检索模型召回相关文档;然后,将检索模型召回的文档做并集处理并重排;最后,将重排后的相关知识输入文本过滤器提取出关键信息文本,并与用户查询合并输入大语言模型生成答案返回给用户。实验结果表明,所提方法在公开的中医药问答数据集和通用领域问答数据集CMRC2018上相较于基于查询改写的对齐优化方法,Recall-Oriented Understudy for Gisting Evaluation Longest common subsequence(ROUGE-L)指标分别提高了9.9个百分点和2.3个百分点,F1指标分别提高了4.1个百分点和1.7个百分点。本文的实验结果验证了所提方法在提升领域问答准确度的有效性。
