Article
Green & Sustainable Science & Technology
Giovanni De Cillis, Onofrio Semeraro, Stefano Leonardi, Pietro De Palma, Stefania Cherubini
Summary: In this study, dynamic mode decomposition (DMD) was used to analyze the wake of the NREL-5MW wind turbine. The selected dynamic modes included tip vortices and modes with low frequencies and large-scale spatial structures. These dynamic modes are crucial for the design optimization of wind farm layout and control.
Article
Physics, Multidisciplinary
Junyu Chai, Wenguang Liu, Xiaolin Wang, Qiong Zhou, Kun Xie, Yujun Wen, Jiangbin Zhang, Pengfei Liu, Hanwei Zhang, Dan Zhang, Zongfu Jiang, Guomin Zhao
Summary: In this study, a high-speed modal decomposition (MD) system is developed to analyze modal coupling in fiber laser oscillator above the transverse mode instability (TMI) threshold. A set of angular-multiplexing transmission functions (TFs) are designed for simultaneous MD and monitoring of the far-field beam profile. Experimental results show that as the co-pumping power increases from 318 W to 397 W, the power fluctuations of the output laser become more drastic, accompanied by changes in the far-field beam profile and the centroid of far-field spot (COFFS), indicating increased velocity of energy transfer between modes. The high-speed MD verifies this process and analyzes the modal components, revealing a decrease in the single cycle of modal coupling from 11 ms to 4 ms, as well as strong mode coupling between modes with relatively large weights.
FRONTIERS IN PHYSICS
(2023)
Article
Computer Science, Interdisciplinary Applications
Binghua Li, Jesus Garicano-Mena, Eusebio Valero
Summary: A novel DMD technique called theta-DMD is proposed for handling non-uniformly sampled data. Experimental results on various datasets show that theta-DMD provides comparable results to the original DMD method on uniformly sampled datasets, and is capable of recovering relevant flow features from non-uniformly sampled databases, unlike DMD.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Computer Science, Interdisciplinary Applications
K. R. Maryada, S. E. Norris
Summary: The parallel algorithm proposed in this study reduces communication costs for deterministic dynamic mode decomposition of large datasets, achieving notable savings in computational costs as well. By compressing high-dimensional snapshot data using horizontal-slicing and parallel Tall and Skinny QR factorisation, the algorithm constructs the Koopman operator with only one communication step. Additionally, avoiding the computation of the orthonormal matrix during the parallel QR factorisation results in significant computational savings, making the current algorithm up to 2.5 times faster than existing parallel approaches without sacrificing accuracy.
JOURNAL OF COMPUTATIONAL SCIENCE
(2022)
Article
Engineering, Civil
Xiao-Mei Yang, Chun-Xu Qu, Ting-Hua Yi, Hong-Nan Li, Hua Liu
Summary: For high-speed railway bridges in operation, it is crucial to study the coupling dynamic performance of train-bridge systems to avoid extreme vibrations that impact bridge safety. Research shows that the vibration of bridges during train passage is closely related to factors such as train speed, heavy axle loads, and span length.
INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS
(2021)
Article
Engineering, Aerospace
Shaowen Chen, Tianhong Tu, Cong Zeng, Qinghe Meng
Summary: This study used large eddy simulation to investigate the effects of endwall pulsed jet and suction-surface sweeping jet actuator controls on corner separation. Modal analysis methods were applied to extract the main structures in the flow field and analyze the mechanism of unsteady jet effects. The results showed that both jet schemes could control corner separation through the induced small-scale flow structures or large-scale streamwise vortex.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Mechanical
W. Stankiewicz
Summary: This article presents a modeling approach called Recursive Dynamic Mode Decomposition (RDMD) for studying coherent structures in fluid flows. The method effectively handles interactions between wakes and combines the advantages of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD). It is especially applicable in unsupervised machine learning applications, including machine learning control.
JOURNAL OF FLUIDS AND STRUCTURES
(2022)
Article
Mechanics
Cong Sun, Lianzhou Wang
Summary: This study analyzed the evolution mechanisms of propeller wakes from near to far field under different inflow conditions. It was found that turbulent inflow contributes to the destabilization process of the tip vortex system by accelerating the interference between adjacent tip-vortex structures and intensifying the instability motion of the tip vortex. The Sparsity-Promoting Dynamic Mode Decomposition (SPDMD) successfully selected the influential dynamic modes for the approximation of the snapshot sequence.
Article
Engineering, Marine
Dehong Fang, Jinsong Zhang, Zhenwei Huang
Summary: The studies on the flow field affected by fish swimming and their three-dimensional dynamics characteristics provide important insights and guidelines for understanding the fish swimming mechanism, developing bionic fish, and bionic fish propulsion systems. This paper uses the 3D velocity data generated by simulations with the Immersed Boundary-Lattice Boltzmann Method (IB-LBM) to investigate the swimming mechanism of bionic fish. The Dynamic Mode Decomposition (DMD) is applied to decompose, reconstruct, and predict the velocity field data in 3D. The results show the presence of distinct 3D characteristics, with semicircular vortex structures on both sides of the fish, and the frequencies obtained from the DMD analysis are consistent with the tail undulation.
Article
Energy & Fuels
Yanzhao Wu, Di Zhu, Ran Tao, Ruofu Xiao, Weichao Liu
Summary: This article discusses the problem of cavitation in the design, manufacture, and operation of pump-turbines and the limitations of traditional research methods. The dynamic mode decomposition (DMD) method is used to study the cavitation of a model pump-turbine and accurately extract the characteristics of the runner under cavitation conditions. The development of cavitation significantly affects the reconstruction of low order modes. The article provides a new research idea for cavitation research of pump-turbines.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Acoustics
Yang Liu, Tommaso Seresini, Jun-Yan Liu, Liwang Liu, Fei Wang, Yang Wang, Christ Glorieux
Summary: Light absorption induced thermoelastic and photoacoustic excitation, combined with laser Doppler vibrometry, were used to analyze the dynamic mechanical behavior of a microcantilever. Three opto-mechanical generation mechanisms were identified, each initiated by modulated optical absorption and heating.
Article
Engineering, Mechanical
Manu Krishnan, Serkan Gugercin, Pablo A. Tarazaga
Summary: Dynamic mode decomposition (DMD) is a popular data-driven modeling approach for identifying spatio-temporal coherent structures in dynamical systems. This work proposes a novel methodology, called wavelet-based dynamic mode decomposition (WDMD), which performs modeling without the restrictive assumption of full state measurements. The WDMD approach is applicable to dynamical systems where internal state vector measurements are not available.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Engineering, Civil
Minggao Chen, Jun Mao, Yanhong Xi
Summary: This paper investigates the effect of vortex shedding on the aerodynamic characteristics of a high-speed train, which in turn affects its safety and stability. The flow field at the tail of the train running in open air and in tunnel is monitored using dynamic monitoring points. Proper orthogonal decomposition analysis is performed to analyze the wake vortex structure under different infrastructure scenarios. The study finds that the wake vortex structure is significantly different between different scenarios, with higher turbulent kinetic energy intensity in the tunnel. Modal decomposition method can identify important flow structures affecting train aerodynamics. Frequency analysis reveals that the modal frequency is higher when running in open air and increases with train speed, while it decreases when running in the tunnel. The stability of the train running in tunnel is worse than that in open air, mainly due to the more complex flow structure around the car body and the drastic change of aerodynamic force in the tunnel.
INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS
(2023)
Article
Engineering, Geological
Yu Otake, Kyohei Shigeno, Yosuke Higo, Shogo Muramatsu
Summary: This paper proposes a practical reliability analysis scheme for earth structures, which is based on dimensionality reduction while preserving spatiotemporal information. The effectiveness of the proposed design scheme and its significant contribution to the practical design of earth structures are demonstrated through a time series seismic deformation analysis of simple embankments on liquefiable sand ground.
GEORISK-ASSESSMENT AND MANAGEMENT OF RISK FOR ENGINEERED SYSTEMS AND GEOHAZARDS
(2022)
Article
Engineering, Aerospace
Song Moru, Yang Bo, Wang Yueheng, Zhou Rui, Li Zixuan
Summary: In this paper, the detailed flowfield during the spike-type rotating stall is obtained through numerical simulation and dynamic mode decomposition. The study reveals three important flow structures in the tip region during the transition from near-stall to stable stall.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Biophysics
Nathan D. Camarillo, Rafael Jimenez-Silva, Frances T. Sheehan
Summary: This article discusses the statistical dependence between multiple measurements from the same participant and provides recommendations for using these measurements when they are not independent.
JOURNAL OF BIOMECHANICS
(2024)
Article
Biophysics
J. Huet, A. -S. Boureau, A. Sarcher, C. Cornu, A. Nordez
Summary: Standard compression in freehand 3D ultrasound induces a bias in volume calculations, but minimal compression and gel pad methods have similar results. With a trained examiner and precautions, the bias can be minimized and become acceptable in clinical applications.
JOURNAL OF BIOMECHANICS
(2024)
Article
Biophysics
C. Lariviere, A. H. Eskandari, H. Mecheri, F. Ghezelbash, D. Gagnon, A. Shirazi-Adl
Summary: Recent developments in musculoskeletal modeling have focused on model customization. Personalization of the spine profile may affect estimates of spinal loading and stability. This study investigates the biomechanical consequences of changes in the spinal profile and finds that personalizing the spine profile has medium to large effects on trunk muscle forces and negligible to small effects on spinal loading and stability.
JOURNAL OF BIOMECHANICS
(2024)
Article
Biophysics
Luke T. Mattar, Arash B. Mahboobin, Adam J. Popchak, William J. Anderst, Volker Musahl, James J. Irrgang, Richard E. Debski
Summary: Exercise therapy fails in about 25.0% of cases for individuals with rotator cuff tears, and one reason for this failure may be the inability to strengthen and balance the muscle forces that keep the humeral head in the correct position. This study developed computational musculoskeletal models to compare the net muscle force before and after exercise therapy between successfully and unsuccessfully treated patients. The study found that unsuccessfully treated patients had less inferiorly oriented net muscle forces, which may increase the risk of impingement.
JOURNAL OF BIOMECHANICS
(2024)
Article
Biophysics
Natsuki Sado, Takeshi Edagawa, Toshihide Fujimori, Shogo Hashimoto, Yoshikazu Okamoto, Takahito Nakajima
Summary: The existing methods for predicting hip and lumbosacral joint centres in Japanese adults are biased and differ between sexes. We propose new regression equations that consider soft-tissue thickness, sex differences, and a height-directional measure, and validate them using leave-one-out cross-validation.
JOURNAL OF BIOMECHANICS
(2024)
Article
Biophysics
Peimin Yu, Xuanzhen Cen, Qichang Mei, Alan Wang, Yaodong Gu, Justin Fernandez
Summary: This study aimed to explore the intra-foot biomechanical differences among individuals with chronic ankle instability (CAI), copers, and healthy individuals during dynamic tasks. The study found that copers and CAI individuals had smaller dorsiflexion angles and copers presented a more eversion position compared to healthy participants. Copers also had greater dorsiflexion angles in the metatarsophalangeal joint and more inversion moments in the subtalar joint during certain tasks. These findings can help in designing interventions to restore ankle joint functions in CAI individuals.
JOURNAL OF BIOMECHANICS
(2024)
Article
Biophysics
Jon Skovgaard Jensen, Anders Holsgaard-Larsen, Anders Stengaard Sorensen, Per Aagaard, Jens Bojsen-Moller
Summary: This study investigates the biomechanical effects of robot-assisted body weight unloading (BWU) on gait patterns in healthy young adults. The results show that dynamic robot-assisted BWU enables reduced kinetic requirements without distorting biomechanically normal gait patterns during overground walking.
JOURNAL OF BIOMECHANICS
(2024)
