Traditional dynamic analysis of mechanical structures,often limited to individual beams or plates,fails to fully capture their dynamic behaviors.In systems where space and mass are constrained,such as the battery supp...Traditional dynamic analysis of mechanical structures,often limited to individual beams or plates,fails to fully capture their dynamic behaviors.In systems where space and mass are constrained,such as the battery support structures in electric aircraft,conventional absorbers and isolators are insufficient for effective vibration control.This study simplifies the battery support structure of electric aircraft as an integrated composite beam consisting of three interconnected beams,and investigated its structural dynamics properties and nonlinear vibration control under thermal conditions caused by battery heat.The nonlinear vibration control is performed using the Nitinol steel wire ropes(Ni Ti-ST),with nonlinear damping properties.The natural frequencies of system are determined using the Rayleigh-Ritz technique.Theoretical results are validated through both Finite Element Method(FEM)and hammer tests.Moreover,the dynamic equations are derived using the Lagrange method and discretized via the Galerkin Truncation Method(GTM).The Harmonic Balance Method(HBM)is used to evaluate the vibration responses of the integrated model,with further verification through the Runge-Kutta Method(RKM).The experiments are conducted to corroborate the theoretical analysis.The results show that the system frequency changes in stages with the increase of the stiffness of the integrated composite beam connection.Especially in the case of varying environments,as the temperature increases,the frequency of system will first increase to a certain maximum value and then gradually decrease.Furthermore,the NiTi-ST effectively reduces vibration in the integrated composite beam,particularly under varying temperatures and external excitations.展开更多
Lithium-rich manganese-based cathode materials(LMCMs)have garnered significant attention in power lithium-ion batteries(LIBs)and energy storage systems due to their superior energy density and costeffectiveness.Howeve...Lithium-rich manganese-based cathode materials(LMCMs)have garnered significant attention in power lithium-ion batteries(LIBs)and energy storage systems due to their superior energy density and costeffectiveness.However,the commercial application of LMCMs is hindered by challenges such as low initial coulombic efficiency,severe voltage decay,and inferior cycling performance.Surface structure degradation has been confirmed as a critical factor contributing to the electrochemical performance deterioration of LMCMs.Herein,we review the recent progress in surface engineering of LMCMs towards next-generation LIBs.Besides classical surface coating,mechanism and functions of surface oxygen vacancies for greatly boosting the electrochemical performance of LMCMs are also summarized in detail.Finally,we discuss the emerging trends and propose future research directions of surface engineering of LMCMs for achieving more efficient improvements.This work underscores the indispensable potential of surface engineering in enhancing the surface structure stability and electrochemical performance of LMCMs as promising candidates for next-generation high-energy LIBs.Synergistic integration of surface engineering and single-crystal technology will be a promising modification strategy for significantly promoting the commercialization of LMCMs,and the corresponding synergistic mechanisms urgently need to be studied for rationally designing high-performance electrodes.More efforts will be devoted to understand the surface engineering of LMCMs for the large-scale application of high-energy LIBs.展开更多
The progression of anodes has markedly promoted the advancement of lithium-ion batteries(LIBs).Typical LIBs using carbon anodes cannot meet the continuously increasing demands for qualified safety and longevity.Spinel...The progression of anodes has markedly promoted the advancement of lithium-ion batteries(LIBs).Typical LIBs using carbon anodes cannot meet the continuously increasing demands for qualified safety and longevity.Spinel lithium titanate(LTO)is a strong contender to replace graphite anodes due to its optimal zero-strain merit and outstanding structural stability.Nevertheless,low reversible capacity and poor rate performance hinder the widespread application of LTO.Amazingly,the promising pseudocapacitive effect enables LTO to surmount the limit of theoretical capacity via boosted surface Li storage,contributing to observably upgraded energy and power densities in a wide temperature range.By leveraging the synergistic effect of multiple modification strategies to create additional active sites,the pseudocapacitive response of LTO can be markedly enhanced.This paper reviews the progress of pseudocapacitive LTO for the first time.We highlight the zero-strain characteristic and pseudocapacitance mechanism of LTO and review the design strategies of pseudocapacitive LTO.Significative issues for further developing pseudocapacitive LTO are proposed.It is worth noting that the pseudocapacitive contribution can greatly improve the low-temperature electrochemical performances of LTO.We anticipate that more efforts will be aroused to study the advanced pseudocapacitive LTO to accelerate the development of next-generation LIBs and energy storage devices.展开更多
The composite leaf spring landing gear of an electric aircraft is optimized.With the strength and workability as constraints and the minimum structural weight as an objective,the two-stage optimization of the leaf spr...The composite leaf spring landing gear of an electric aircraft is optimized.With the strength and workability as constraints and the minimum structural weight as an objective,the two-stage optimization of the leaf spring landing gear with glass fiber unidirectional prepreg is carried out using a genetic algorithm,namely,the optimization of continuous thickness of layup,and the optimization of the layup sequence and discrete thickness.In the optimization process,the ground loads are calculated according to the structural stiffness of each chromosome,thus the stiffness constraints are relaxed,and the optimization results are compared with those using stiffness constraints.The static experiment verification reveals that the numerical simulation and experimental results are consistent,that is,the optimized leaf spring meets the strength requirements.The results show that the leaf spring landing gear based on two-stage optimization method achieves the objective of weight reduction.展开更多
Love＇s first approximation theory is used to analyze the natural frequencies of rotating functionally graded cylindrical shells. To verify the validity of the present method, the natural frequencies of the simply sup...Love＇s first approximation theory is used to analyze the natural frequencies of rotating functionally graded cylindrical shells. To verify the validity of the present method, the natural frequencies of the simply supported non-rotating isotropic cylindrical shell and the functionally graded cylindrical shell are compared with available published results. Good agreement is obtained. The effects of the power law index, the wave numbers along the x- and O-directions, and the thickness-to-radius ratio on the natural frequencies of the simply supported rotating functionally graded cylindrical shell are investigated by several numerical examples. It is found that the fundamental frequencies of the backward waves increase with the increasing rotating speed, the fundamental frequencies of the forward waves decrease with the increasing rotating speed, and the forward and backward waves frequencies increase with the increasing thickness-to-radius ratio.展开更多
Taking Beijing–Shanghai High-speed Railway(the section of Zhenjiangnan Station) for example,this paper applied UAV remote sensing data and GIS spatial analysis to analyze current land use types in this section,on thi...Taking Beijing–Shanghai High-speed Railway(the section of Zhenjiangnan Station) for example,this paper applied UAV remote sensing data and GIS spatial analysis to analyze current land use types in this section,on this basis used landscape pattern indices that showed high correlation with land use changes for the quantitative analysis and evaluation of ecosystem structure in the study area and also landscape pattern after the construction of high-speed railway.The results showed that UAV images performed well in the evaluation of railway landscape ecological environment,landscape structure and features represented by the selected landscape pattern indices in this paper were applicable,and capable of ensuring scientific evaluation of ecological environmental impact;the overall landscape pattern of the Zhenjiangnan Station section(Beijing–Shanghai High-speed Railway) after completion was moderate,and local ecosystem was damaged,thus scientific and reasonable ecological planning was required to design and change landscape structure.展开更多
For low-cost unmanned aerial vehicles,it is practically important to estimate flight height using the measurements from low-cost accelerometer and barometer sensors.In this paper,we propose a simple two-step strategy ...For low-cost unmanned aerial vehicles,it is practically important to estimate flight height using the measurements from low-cost accelerometer and barometer sensors.In this paper,we propose a simple two-step strategy to fuse the measurements from the two sensors.In the first step,two different filters,moving average filter and Kalman filter,are adopted to pre-process the measurements from accelerometer and barometer,respectively.In the second step,a properly designed complementary filter is employed for high-precision height estimation.Several experimental comparison results on a small-size quadrotor demonstrate the effectiveness of the strategy.The strategy is further combined with a simple height controller to yield a height feedback-control scheme.The closed-loop experimental results show that 8-cm and 20-cm control accuracies are achieved for 5-m-and 10-m-height tracking tasks,respectively.展开更多
Great attention has been given to high-performance and inexpensive lithiumion batteries(LIBs)in response to the ever-increasing demand for the explosive growth of electric vehicles(EVs).High-performance and low-cost C...Great attention has been given to high-performance and inexpensive lithiumion batteries(LIBs)in response to the ever-increasing demand for the explosive growth of electric vehicles(EVs).High-performance and low-cost Co-freeNi-rich layered cathodes are considered one of the most favorable candidates for nextgeneration LIBs because the current supply chain of EVs relies heavily on scarce and expensive Co.Herein,we review the recent research progress on Co-free Nirich layered cathodes,emphasizing on analyzing the necessity of replacing Co and the popular improvment methods.The current advancements in the design strategies of Co-free Ni-rich layered cathodes are summarized in detail.Despite considerable improvements achieved so far,the main technical challenges contributing to the deterioration of Co-free Ni-rich cathodes such as detrimental phase transitions,crack formation,and severe interfacial side reactions,are difficult to resolve by a single technique.The cooperation of multiple modification strategies is expected to accelerate the industrialization of Co-free Ni-rich layered cathodes,and the corresponding synergistic mechanisms urgently need to be studied.More effects will be aroused to explore high-performance Co-free Ni-rich layered cathodes to promote the sustainable development of LIBs.展开更多
基金supported by the National Natural Science Foundation of China(No.12272240)the Liaoning Revitalization Talents Program,China(No.XLYC2203197)。
文摘Traditional dynamic analysis of mechanical structures,often limited to individual beams or plates,fails to fully capture their dynamic behaviors.In systems where space and mass are constrained,such as the battery support structures in electric aircraft,conventional absorbers and isolators are insufficient for effective vibration control.This study simplifies the battery support structure of electric aircraft as an integrated composite beam consisting of three interconnected beams,and investigated its structural dynamics properties and nonlinear vibration control under thermal conditions caused by battery heat.The nonlinear vibration control is performed using the Nitinol steel wire ropes(Ni Ti-ST),with nonlinear damping properties.The natural frequencies of system are determined using the Rayleigh-Ritz technique.Theoretical results are validated through both Finite Element Method(FEM)and hammer tests.Moreover,the dynamic equations are derived using the Lagrange method and discretized via the Galerkin Truncation Method(GTM).The Harmonic Balance Method(HBM)is used to evaluate the vibration responses of the integrated model,with further verification through the Runge-Kutta Method(RKM).The experiments are conducted to corroborate the theoretical analysis.The results show that the system frequency changes in stages with the increase of the stiffness of the integrated composite beam connection.Especially in the case of varying environments,as the temperature increases,the frequency of system will first increase to a certain maximum value and then gradually decrease.Furthermore,the NiTi-ST effectively reduces vibration in the integrated composite beam,particularly under varying temperatures and external excitations.
基金financially supported by the National Natura Science Foundation of China(51108455,52106264)Civil Aviation Safety Capacity Building Fund(ADSA2022026)+2 种基金Liaoning Revitalization Talents Program(XLYC2018013)Liaoning Province AppliedFoundation Research Program Project(2023JH2/101300215)Unveiled the List of Local Service Projects from Education Department of Liaoning Province(JYTMS20230227)。
文摘Lithium-rich manganese-based cathode materials(LMCMs)have garnered significant attention in power lithium-ion batteries(LIBs)and energy storage systems due to their superior energy density and costeffectiveness.However,the commercial application of LMCMs is hindered by challenges such as low initial coulombic efficiency,severe voltage decay,and inferior cycling performance.Surface structure degradation has been confirmed as a critical factor contributing to the electrochemical performance deterioration of LMCMs.Herein,we review the recent progress in surface engineering of LMCMs towards next-generation LIBs.Besides classical surface coating,mechanism and functions of surface oxygen vacancies for greatly boosting the electrochemical performance of LMCMs are also summarized in detail.Finally,we discuss the emerging trends and propose future research directions of surface engineering of LMCMs for achieving more efficient improvements.This work underscores the indispensable potential of surface engineering in enhancing the surface structure stability and electrochemical performance of LMCMs as promising candidates for next-generation high-energy LIBs.Synergistic integration of surface engineering and single-crystal technology will be a promising modification strategy for significantly promoting the commercialization of LMCMs,and the corresponding synergistic mechanisms urgently need to be studied for rationally designing high-performance electrodes.More efforts will be devoted to understand the surface engineering of LMCMs for the large-scale application of high-energy LIBs.
基金financially supported by the National Natural Science Foundation of China(51108455,52106264)Civil Aviation Safety Capacity Building Fund(ADSA2022026)+2 种基金Liaoning Revitalization Talents Program(XLYC2018013)Liaoning Province AppliedFoundation Research Program Project(2023JH2/101300215)Unveiled the List of Local Service Projects from Education Department of Liaoning Province(JYTMS20230227)。
文摘The progression of anodes has markedly promoted the advancement of lithium-ion batteries(LIBs).Typical LIBs using carbon anodes cannot meet the continuously increasing demands for qualified safety and longevity.Spinel lithium titanate(LTO)is a strong contender to replace graphite anodes due to its optimal zero-strain merit and outstanding structural stability.Nevertheless,low reversible capacity and poor rate performance hinder the widespread application of LTO.Amazingly,the promising pseudocapacitive effect enables LTO to surmount the limit of theoretical capacity via boosted surface Li storage,contributing to observably upgraded energy and power densities in a wide temperature range.By leveraging the synergistic effect of multiple modification strategies to create additional active sites,the pseudocapacitive response of LTO can be markedly enhanced.This paper reviews the progress of pseudocapacitive LTO for the first time.We highlight the zero-strain characteristic and pseudocapacitance mechanism of LTO and review the design strategies of pseudocapacitive LTO.Significative issues for further developing pseudocapacitive LTO are proposed.It is worth noting that the pseudocapacitive contribution can greatly improve the low-temperature electrochemical performances of LTO.We anticipate that more efforts will be aroused to study the advanced pseudocapacitive LTO to accelerate the development of next-generation LIBs and energy storage devices.
基金the Natural Science Foundation of Liaoning (No. 20180550824)。
文摘The composite leaf spring landing gear of an electric aircraft is optimized.With the strength and workability as constraints and the minimum structural weight as an objective,the two-stage optimization of the leaf spring landing gear with glass fiber unidirectional prepreg is carried out using a genetic algorithm,namely,the optimization of continuous thickness of layup,and the optimization of the layup sequence and discrete thickness.In the optimization process,the ground loads are calculated according to the structural stiffness of each chromosome,thus the stiffness constraints are relaxed,and the optimization results are compared with those using stiffness constraints.The static experiment verification reveals that the numerical simulation and experimental results are consistent,that is,the optimized leaf spring meets the strength requirements.The results show that the leaf spring landing gear based on two-stage optimization method achieves the objective of weight reduction.
文摘Love＇s first approximation theory is used to analyze the natural frequencies of rotating functionally graded cylindrical shells. To verify the validity of the present method, the natural frequencies of the simply supported non-rotating isotropic cylindrical shell and the functionally graded cylindrical shell are compared with available published results. Good agreement is obtained. The effects of the power law index, the wave numbers along the x- and O-directions, and the thickness-to-radius ratio on the natural frequencies of the simply supported rotating functionally graded cylindrical shell are investigated by several numerical examples. It is found that the fundamental frequencies of the backward waves increase with the increasing rotating speed, the fundamental frequencies of the forward waves decrease with the increasing rotating speed, and the forward and backward waves frequencies increase with the increasing thickness-to-radius ratio.
基金Sponsored by Environmental Protection Fund of China-"123 Project"of Liaoning Environmental Scientific Research&Education(CEPF2010-123-2-10)
文摘Taking Beijing–Shanghai High-speed Railway(the section of Zhenjiangnan Station) for example,this paper applied UAV remote sensing data and GIS spatial analysis to analyze current land use types in this section,on this basis used landscape pattern indices that showed high correlation with land use changes for the quantitative analysis and evaluation of ecosystem structure in the study area and also landscape pattern after the construction of high-speed railway.The results showed that UAV images performed well in the evaluation of railway landscape ecological environment,landscape structure and features represented by the selected landscape pattern indices in this paper were applicable,and capable of ensuring scientific evaluation of ecological environmental impact;the overall landscape pattern of the Zhenjiangnan Station section(Beijing–Shanghai High-speed Railway) after completion was moderate,and local ecosystem was damaged,thus scientific and reasonable ecological planning was required to design and change landscape structure.
基金supported by the National Natural Science Foundation of China(Grant No.61773095)the Fundamental Research Funds for the Central Universities(Grant No.ZYGX2016J161)at UESTC.
文摘For low-cost unmanned aerial vehicles,it is practically important to estimate flight height using the measurements from low-cost accelerometer and barometer sensors.In this paper,we propose a simple two-step strategy to fuse the measurements from the two sensors.In the first step,two different filters,moving average filter and Kalman filter,are adopted to pre-process the measurements from accelerometer and barometer,respectively.In the second step,a properly designed complementary filter is employed for high-precision height estimation.Several experimental comparison results on a small-size quadrotor demonstrate the effectiveness of the strategy.The strategy is further combined with a simple height controller to yield a height feedback-control scheme.The closed-loop experimental results show that 8-cm and 20-cm control accuracies are achieved for 5-m-and 10-m-height tracking tasks,respectively.
基金National Natural Science Foundation of China,Grant/Award Numbers:51108455,52106264Civil Aviation Safety Capacity Building Fund,Grant/Award Number:ADSA2022026+1 种基金LiaoNing Revitalization Talents Program,Grant/Award Number:XLYC2008013Liaoning Province Applied Foundation Research Program Project,Grant/Award Number:2023JH2/101300215。
文摘Great attention has been given to high-performance and inexpensive lithiumion batteries(LIBs)in response to the ever-increasing demand for the explosive growth of electric vehicles(EVs).High-performance and low-cost Co-freeNi-rich layered cathodes are considered one of the most favorable candidates for nextgeneration LIBs because the current supply chain of EVs relies heavily on scarce and expensive Co.Herein,we review the recent research progress on Co-free Nirich layered cathodes,emphasizing on analyzing the necessity of replacing Co and the popular improvment methods.The current advancements in the design strategies of Co-free Ni-rich layered cathodes are summarized in detail.Despite considerable improvements achieved so far,the main technical challenges contributing to the deterioration of Co-free Ni-rich cathodes such as detrimental phase transitions,crack formation,and severe interfacial side reactions,are difficult to resolve by a single technique.The cooperation of multiple modification strategies is expected to accelerate the industrialization of Co-free Ni-rich layered cathodes,and the corresponding synergistic mechanisms urgently need to be studied.More effects will be aroused to explore high-performance Co-free Ni-rich layered cathodes to promote the sustainable development of LIBs.
