Numerical investigation on combined wave damping effect of pneumatic breakwater and submerged breakwater

Wang, Yanxu,Yin, Zegao,Liu, Yong,Yu, Ning,Zou, Wei The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper attempts to combine the pneumatic breakwater and submerged breakwater to increase the effectiveness of wave damping for long-period waves. A series of physical experiments concerning pneumatic breakwater, submerged breakwater and their joint breakwater was conducted and used to validate a mathematical model based on Reynolds-averaged Navier-Stokes equations, the RNG $k-{\varepsilon}$ turbulence model and the VOF method. In addition, the mathematical model was used to investigate the wave transmission coefficients of three breakwaters. The nonlinear wave propagation behaviors and the energy transfer from lower frequencies to higher frequencies after the submerged breakwater were investigated in detail. Furthermore, an optimal arrangement between pneumatic breakwater and submerged breakwater was obtained for damping longer-period waves that cannot be damped effectively by the pneumatic breakwater alone. In addition, the reason for the appearance of the combination effect is that part of the energy of the transmitted waves over the submerged breakwater transfers to shorter-period waves. Finally, the impact of the joint breakwater on the wave field during wave propagation process was investigated.

Numerical investigation on combined wave damping effect of pneumatic breakwater and submerged breakwater

Yanxu Wang,Zegao Yin,Yong Liu,Ning Yu,Wei Zou 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper attempts to combine the pneumatic breakwater and submerged breakwater to increase the effectiveness of wave damping for long-period waves. A series of physical experiments concerning pneumatic breakwater, submerged breakwater and their joint breakwater was conducted and used to validate a mathematical model based on Reynolds-averaged Navier-Stokes equations, the RNG k-ε turbulence model and the VOF method. In addition, the mathematical model was used to investigate the wave transmission coefficients of three breakwaters. The nonlinear wave propagation behaviors and the energy transfer from lower frequencies to higher frequencies after the submerged breakwater were investigated in detail. Furthermore, an optimal arrangement between pneumatic breakwater and submerged breakwater was obtained for damping longer-period waves that cannot be damped effectively by the pneumatic breakwater alone. In addition, the reason for the appearance of the combination effect is that part of the energy of the transmitted waves over the submerged breakwater transfers to shorterperiod waves. Finally, the impact of the joint breakwater on the wave field during wave propagation process was investigated.

Backstepping method based controller design for third-order truck platoon robust to dynamic uncertainty and external disturbance

Jianbo Feng,Liyang He,Yanxue Wang,Jianwei Yang,Hongbin Ren 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

The vehicle platoon is subject to dynamic uncertainty and external disturbance, such as air drag and parameter variation in practice, so lack of consideration for those factors can deteriorate control performance. This paper proposes a nonlinear control algorithm based on a novel adaptive backstepping method to cope with the uncertainty and disturbance. The virtual controller in the backstepping method utilizes only the local information of the individual vehicle, rather than the global state information, in the control algorithm design. A third-order vehicle dynamics model was built to incorporate the nonlinearity and the factor of actuation delay. The fuzzy logic system (FLS) is applied to estimate the nonlinearity in vehicle dynamics to facilitate the adaptive control. Five scenarios with different settings were constructed to verify the control performance in the simulation, which indicates the effectiveness and robustness of the controller to dynamic uncertainty and external disturbance.

Study on damage detection software of beam-like structures

Jiawei Xiang,Zhansi Jiang,Yanxue Wang,Xuefeng Chen 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

A simply structural damage detection software is developed to identification damage in beams. According to linear fracture mechanics theory, the localized additional flexibility in damage vicinity can be represented by a lumped parameter element. The damaged beam is modeled by waveletbased elements to gain the first three frequencies precisely. The first three frequencies influencing functions of damage location and depth are approximated by means of surface-fitting techniques to gain damage detection database of forward problem. Then the first three measured natural frequencies are employed as inputs to solve inverse problem and the intersection of the three frequencies contour lines predict the damage location and depth. The DLL (Dynamic Linkable Library) file of damage detection method is coded by C++ and the corresponding interface of software is coded by virtual instrument software LabVIEW. Finally, the software is tested on beams and shafts in engineering. It is shown that the presented software can be used in actual engineering structures.

A Novel Method of Phase-Shifted Full-Bridge Converter to Improve Efficiency under Light Load Condition

Lei Zhao,Haoyu Li,Yanxue Yu,Yutian Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The main theme of this paper is to propose a novel peak current mode control method to reduce the loss of phase-shifted full-bridge (PSFB) converter under light load condition. The proposed control method can adjust the switching frequency of the converter to keep the on-time of switches fixed. According to the loss analysis model in discontinuous current mode operation, the switching frequency is proportional to load current and the efficiency is independent from the load. Moreover, the small signal model of the PSFB converter with the proposed control method is presented. A digital-controlled experimental system is set up. The proposed method is investigated and confirmed by experimental results. Experimental results show that the efficiency and dynamic performance can be improved. These results confirm the effectiveness of the proposed control method.

Study on damage detection software of beam-like structures

Xiang, Jiawei,Jiang, Zhansi,Wang, Yanxue,Chen, Xuefeng Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

A simply structural damage detection software is developed to identification damage in beams. According to linear fracture mechanics theory, the localized additional flexibility in damage vicinity can be represented by a lumped parameter element. The damaged beam is modeled by wavelet-based elements to gain the first three frequencies precisely. The first three frequencies influencing functions of damage location and depth are approximated by means of surface-fitting techniques to gain damage detection database of forward problem. Then the first three measured natural frequencies are employed as inputs to solve inverse problem and the intersection of the three frequencies contour lines predict the damage location and depth. The DLL (Dynamic Linkable Library) file of damage detection method is coded by C++ and the corresponding interface of software is coded by virtual instrument software LabVIEW. Finally, the software is tested on beams and shafts in engineering. It is shown that the presented software can be used in actual engineering structures.

A new method to detect cracks in plate-like structures with though-thickness cracks

Xiang, Jiawei,Nackenhorst, Udo,Wang, Yanxue,Jiang, Yongying,Gao, Haifeng,He, Yumin Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.3

In this paper, a simple two-step method for structural vibration-based health monitoring for beam-like structures have been extended to plate-like structures with though-thickness cracks. Crack locations and severities of plate-like structures are detected using a hybrid approach. The interval wavelet transform is employed to extract crack singularity locations from mode shape and support vector regression (SVR) is applied to predict crack serviettes form crack severity detection database (the relationship of natural frequencies and crack serviettes) using several natural frequencies as inputs. Of particular interest is the natural frequencies estimation for cracked plate-like structures using Rayleigh quotient. Only the natural frequencies and mode shapes of intact structures are needed to calculate the natural frequencies of cracked plate-like structures using a simple formula. The crack severity detection database can be easily obtained with this formula. The hybrid method is investigated using numerical simulation and its validity of the usage of interval wavelet transform and SVR are addressed.

A new method to detect cracks in plate-like structures with though-thickness cracks

Jiawei Xiang,Yongying Jiang,Udo Nackenhorst,Yanxue Wang,Haifeng Gao,Yumin He 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.3

In this paper, a simple two-step method for structural vibration-based health monitoring for beam-like structures have been extended to plate-like structures with though-thickness cracks. Crack locations and severities of plate-like structures are detected using a hybrid approach. The interval wavelet transform is employed to extract crack singularity locations from mode shape and support vector regression (SVR) is applied to predict crack serviettes form crack severity detection database (the relationship of natural frequencies and crack serviettes) using several natural frequencies as inputs. Of particular interest is the natural frequencies estimation for cracked plate-like structures using Rayleigh quotient. Only the natural frequencies and mode shapes of intact structures are needed to calculate the natural frequencies of cracked plate-like structures using a simple formula. The crack severity detection database can be easily obtained with this formula. The hybrid method is investigated using numerical simulation and its validity of the usage of interval wavelet transform and SVR are addressed.

A simple method to detect cracks in beam-like structures

Xiang, Jiawei,Matsumoto, Toshiro,Long, Jiangqi,Wang, Yanxue,Jiang, Zhansi Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.4

This study suggests a simple two-step method for structural vibration-based health monitoring for beam-like structures which only utilizes mode shape curvature and few natural frequencies of the structures in order to detect and localize cracks. The method is firstly based on the application of wavelet transform to detect crack locations from mode shape curvature. Then particle swarm optimization is applied to evaluate crack depth. As the Rayleigh quotient is introduced to estimate natural frequencies of cracked beams, the relationship of natural frequencies and crack depths can be easily obtained with only a simple formula. The method is demonstrated and validated numerically, using the numerical examples (cantilever beam and simply supported shaft) in the literature, and experimentally for a cantilever beam. Our results show that mode shape curvature and few estimated natural frequencies can be used to detect crack locations and depths precisely even under a certain level of noise. The method can be extended for health monitoring of other more complicated structures.

A simple method to detect cracks in beam-like structures

Jiawei Xiang,Toshiro Matsumoto,Jiangqi Long,Yanxue Wang,Zhansi Jiang 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.4

This study suggests a simple two-step method for structural vibration-based health monitoring for beam-like structures which only utilizes mode shape curvature and few natural frequencies of the structures in order to detect and localize cracks. The method is firstly based on the application of wavelet transform to detect crack locations from mode shape curvature. Then particle swarm optimization is applied to evaluate crack depth. As the Rayleigh quotient is introduced to estimate natural frequencies of cracked beams, the relationship of natural frequencies and crack depths can be easily obtained with only a simple formula. The method is demonstrated and validated numerically, using the numerical examples (cantilever beam and simply supported shaft) in the literature, and experimentally for a cantilever beam. Our results show that mode shape curvature and few estimated natural frequencies can be used to detect crack locations and depths precisely even under a certain level of noise. The method can be extended for health monitoring of other more complicated structures.