There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed a...There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed and implemented into the 3D NMM,eliminating the false-volume expansion and false-rotation strain/stress problems.The Jaumann rate is used to measure the material rotation,and the geometric stiffness built on the Jaumann rate is deduced.The incremental formulas of the MSAD-based 3D NMM and a practical guide on the implementation of the MSAD theory are given in detail and exemplified.The new theory and formulas can be applied to analyze both large rotation and large deformation problems.Based on the hypoelasto-plasticity theory and the unified strength theory,the unified yield criterion with associated flow rule is implemented into the MSAD-based 3D NMM.Several typical examples are studied,showing the advantage and potential of the new MSAD theory and the MSAD-based 3D NMM.展开更多
Based on the decomposition theory of the U（1） gauge potential, the inner structure of the statistical gauge potential in the Chern-Simons-Ginzburg-Landau （CSGL） theory is studied. We give a new creation mechanism ...Based on the decomposition theory of the U（1） gauge potential, the inner structure of the statistical gauge potential in the Chern-Simons-Ginzburg-Landau （CSGL） theory is studied. We give a new creation mechanism of the statistical gauge potential, Furthermore, making use of the b-mapping topological current theory, we obtain the precise topological expression of the statistical magnetic field, which takes the topological information of the vortices.展开更多
Given the global lack of effective analysis methods for the impact of design parameter tolerance on performance deviation in the vehicle proof-of-concept stage,it is difficult to decompose performance tolerance to des...Given the global lack of effective analysis methods for the impact of design parameter tolerance on performance deviation in the vehicle proof-of-concept stage,it is difficult to decompose performance tolerance to design parameter tolerance.This study proposes a set of consistency analysis methods for vehicle steering performance.The process of consistency analysis and control of automotive performance in the conceptual design phase is proposed for the first time.A vehicle dynamics model is constructed,and the multi-objective optimization software Isight is used to optimize the steering performance of the car.Sensitivity analysis is used to optimize the design performance value.The tolerance interval of the performance is obtained by comparing the original car performance value with the optimized value.With the help of layer-by-layer decomposition theory and interval mathematics,automotive performance tolerance has been decomposed into design parameter tolerance.Through simulation and real vehicle experiments,the validity of the consistency analysis and control method presented in this paper are verified.The decomposition from parameter tolerance to performance tolerance can be achieved at the conceptual design stage.展开更多
The gearbox of a wind turbine （WT） has dominant failure rates and highest downtime loss among all WT subsystems. Thus, gearbox health assessment for maintenance cost reduction is of paramount importance. The concurr...The gearbox of a wind turbine （WT） has dominant failure rates and highest downtime loss among all WT subsystems. Thus, gearbox health assessment for maintenance cost reduction is of paramount importance. The concurrence of multiple faults in gearbox components is a common phenomenon due to fault induction mechanism. This problem should be considered before planning to replace the components of the WT gearbox. Therefore, the key fault patterns should be reliably identified from noisy observation data for the development of an effective maintenance strategy. However, most of the existing studies focusing on multiple fault diagnosis always suffer from inappropriate division of fault information in order to satisfy various rigorous decomposition principles or statistical assumptions, such as the smooth envelope principle of ensemble empirical mode decomposition and the mutual independence assumption of independent component analysis. Thus, this paper presents a joint subspace learning-based multiple fault detection （JSLMFD） technique to construct different subspaces adaptively for different fault pattems. Its main advantage is its capability to learn multiple fault subspaces directly from the observation signal itself. It can also sparsely concentrate the feature information into a few dominant subspace coefficients. Furthermore, it can eliminate noise by simply performing coefficient shrinkage operations. Consequently, multiple fault patterns are reliably identified by utilizing the maximum fault information criterion. The superiority of JSL-MFD in multiple fault separation and detection is comprehensively investigated and verified by the analysis of a data set of a 750 kW WT gearbox. Results show that JSL-MFD is superior to a state-of-the-art technique in detecting hidden fault patterns and enhancing detection accuracy.展开更多
Carbon emissions from engineering construction play a critical role in achieving urban carbon peak and neutrality goals.This study evaluates the carbon emission reduction benefits of the renovation project of Yihe Bri...Carbon emissions from engineering construction play a critical role in achieving urban carbon peak and neutrality goals.This study evaluates the carbon emission reduction benefits of the renovation project of Yihe Bridge on Beijing Road using a life cycle assessment(LCA)approach.The carbon emissions resulting from the renovation were compared with those of an alternative demolition and reconstruction plan.The calculation boundary for carbon emissions during the bridge construction period was defined based on the renovation project’s specifics,dividing the process into three stages:material production,material transportation,and mechanical construction.By integrating factor decomposition theory with the carbon emission factor method,a carbon emission mode was developed,allowing a comprehensive quantitative analysis for the construction period.Results indicate that total carbon emissions were 84560.40 t,with material production contributing 94.73%,transportation 1.47%,and mechanical construction 3.80%.The carbon emission intensity of the newly expanded bridge section was 2.11 t/m^(2).Compared to the demolition and reconstruction,the renovation plan reduced carbon emissions by 53643.44 t,achieving a 38.81%reduction.展开更多
基金This research is supported by the National Basic Research Program of China(973 Program,Grant No.2014CB047100)the National Natural Science Foundation of China(Grant Nos.41472289,51179185 and 41807275).
文摘There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed and implemented into the 3D NMM,eliminating the false-volume expansion and false-rotation strain/stress problems.The Jaumann rate is used to measure the material rotation,and the geometric stiffness built on the Jaumann rate is deduced.The incremental formulas of the MSAD-based 3D NMM and a practical guide on the implementation of the MSAD theory are given in detail and exemplified.The new theory and formulas can be applied to analyze both large rotation and large deformation problems.Based on the hypoelasto-plasticity theory and the unified strength theory,the unified yield criterion with associated flow rule is implemented into the MSAD-based 3D NMM.Several typical examples are studied,showing the advantage and potential of the new MSAD theory and the MSAD-based 3D NMM.
文摘Based on the decomposition theory of the U（1） gauge potential, the inner structure of the statistical gauge potential in the Chern-Simons-Ginzburg-Landau （CSGL） theory is studied. We give a new creation mechanism of the statistical gauge potential, Furthermore, making use of the b-mapping topological current theory, we obtain the precise topological expression of the statistical magnetic field, which takes the topological information of the vortices.
文摘Given the global lack of effective analysis methods for the impact of design parameter tolerance on performance deviation in the vehicle proof-of-concept stage,it is difficult to decompose performance tolerance to design parameter tolerance.This study proposes a set of consistency analysis methods for vehicle steering performance.The process of consistency analysis and control of automotive performance in the conceptual design phase is proposed for the first time.A vehicle dynamics model is constructed,and the multi-objective optimization software Isight is used to optimize the steering performance of the car.Sensitivity analysis is used to optimize the design performance value.The tolerance interval of the performance is obtained by comparing the original car performance value with the optimized value.With the help of layer-by-layer decomposition theory and interval mathematics,automotive performance tolerance has been decomposed into design parameter tolerance.Through simulation and real vehicle experiments,the validity of the consistency analysis and control method presented in this paper are verified.The decomposition from parameter tolerance to performance tolerance can be achieved at the conceptual design stage.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 51505364 and 51335006）, the National Key Basic Research Program of China （Grant No. 2015CB057400）, and the Program for Changjiang Scholars. The authors thank NREL for supporting this work and providing the vibration data used for the validation of the JSL-MFD technique.
文摘The gearbox of a wind turbine （WT） has dominant failure rates and highest downtime loss among all WT subsystems. Thus, gearbox health assessment for maintenance cost reduction is of paramount importance. The concurrence of multiple faults in gearbox components is a common phenomenon due to fault induction mechanism. This problem should be considered before planning to replace the components of the WT gearbox. Therefore, the key fault patterns should be reliably identified from noisy observation data for the development of an effective maintenance strategy. However, most of the existing studies focusing on multiple fault diagnosis always suffer from inappropriate division of fault information in order to satisfy various rigorous decomposition principles or statistical assumptions, such as the smooth envelope principle of ensemble empirical mode decomposition and the mutual independence assumption of independent component analysis. Thus, this paper presents a joint subspace learning-based multiple fault detection （JSLMFD） technique to construct different subspaces adaptively for different fault pattems. Its main advantage is its capability to learn multiple fault subspaces directly from the observation signal itself. It can also sparsely concentrate the feature information into a few dominant subspace coefficients. Furthermore, it can eliminate noise by simply performing coefficient shrinkage operations. Consequently, multiple fault patterns are reliably identified by utilizing the maximum fault information criterion. The superiority of JSL-MFD in multiple fault separation and detection is comprehensively investigated and verified by the analysis of a data set of a 750 kW WT gearbox. Results show that JSL-MFD is superior to a state-of-the-art technique in detecting hidden fault patterns and enhancing detection accuracy.
文摘Carbon emissions from engineering construction play a critical role in achieving urban carbon peak and neutrality goals.This study evaluates the carbon emission reduction benefits of the renovation project of Yihe Bridge on Beijing Road using a life cycle assessment(LCA)approach.The carbon emissions resulting from the renovation were compared with those of an alternative demolition and reconstruction plan.The calculation boundary for carbon emissions during the bridge construction period was defined based on the renovation project’s specifics,dividing the process into three stages:material production,material transportation,and mechanical construction.By integrating factor decomposition theory with the carbon emission factor method,a carbon emission mode was developed,allowing a comprehensive quantitative analysis for the construction period.Results indicate that total carbon emissions were 84560.40 t,with material production contributing 94.73%,transportation 1.47%,and mechanical construction 3.80%.The carbon emission intensity of the newly expanded bridge section was 2.11 t/m^(2).Compared to the demolition and reconstruction,the renovation plan reduced carbon emissions by 53643.44 t,achieving a 38.81%reduction.
