Article
Mathematics
Elbaz I. Abouelmagd, Sawsan Alhowaity, Zouhair Diab, Juan L. G. Guirao, Mahmoud H. Shehata
Summary: In this work, we compared and analyzed several perturbation approaches, evaluated the necessary conditions for constructing periodic solutions under quantum corrections, and applied them to develop a Lunar theory and families of periodic orbits in the spatial quantized Hill problem.
Article
Engineering, Mechanical
Fabia Bayer, Remco I. Leine
Summary: This paper aims to study nonlinear time-periodic systems using the Koopman operator, which approximates the dynamics of a nonlinear system by a higher-order linear time-invariant system. A specific choice of Koopman basis functions, incorporating the Taylor and Fourier bases, is proposed for the considered system class. This basis allows recovery of all necessary equations for harmonic balance method and Hill analysis directly from the linear lifted dynamics. The key idea of this paper is to use this lifted dynamics to formulate a new method to obtain stability information from the Hill matrix, circumventing the error-prone and computationally intense task of sorting.
NONLINEAR DYNAMICS
(2023)
Article
Mechanics
Zhideng Zhou, Xiang I. A. Yang, Fengshun Zhang, Xiaolei Yang
Summary: In this study, a wall model is developed using the wall-resolved large-eddy simulation (WRLES) data of flow over periodic hills (PH) and the law of the wall (LoW) for data-driven wall-modeled large-eddy simulations of various wall-bounded turbulent flows. A feedforward neural network (FNN) is employed to construct the model. The performance of the obtained FNN_PH-LoW model is successfully evaluated using the direct numerical simulation data of turbulent channel flows and the WRLES data of PH cases, and it is applied to turbulent channel flows with a wide range of Reynolds numbers.
Article
Mechanics
Abdelouahab Mohammed-Taifour, Julien Weiss
Summary: Experimental results show that periodic forcing artificially reduces the size of the TSB by moving separation downstream and reattachment upstream. The TSB responds to upstream forcing with a characteristic time scale similar to the breathing motion, supporting a mechanism where low-frequency contraction and expansion is a response to upstream perturbations affecting separation and reattachment positions.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
Frederik J. Thomsen, Lisa Rapp, Fabian Bergmann, Walter Zimmermann
Summary: In this study, a novel bifurcation in conserved systems is identified, which leads to a transition from active phase separation to extended spatially periodic patterns or hybrid states. The resulting multistable patterns are predicted using a generic dissipative model. The transitions are system-spanning phenomena with potential applications in motility-induced phase separation and chemotactic systems.
NEW JOURNAL OF PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Hsin-Fu Huang, Kun-Hao Huang, Ju-En Kuo
Summary: This study formulates a set of dimensionless groups and constraints on their values to indicate the parametric combinations in time-periodic electro-osmotic microchannel flows with asymmetric hydrodynamic slip. It is found that multiple minimal enhancement instances may be achieved during a zeta potential sweep.
Article
Mechanics
X. Guan, J-M Vanden-Broeck, Z. Wang
Summary: The study considers two-dimensional periodic interfacial gravity waves between two homogeneous fluids of finite depth. Highly accurate solutions are obtained using a boundary-integral-equation method coupled with Fourier expansions. The numerical results show excellent agreement with those obtained using a different scheme, exploring the global bifurcation mechanism and identifying three types of limiting wave profiles.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Computer Science, Interdisciplinary Applications
Martin Gehrke, Thomas Rung
Summary: The article assesses a cumulant lattice Boltzmann method in wall-bounded, separated turbulent shear flows. The approach successfully resolves complex turbulent flows without the need for ad hoc modeling by using a recently published parameterized cumulant collision operator. The evaluation focuses on the flow over a periodic hill and determines the required minimum resolution.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS
(2022)
Review
Clinical Neurology
Antonella Gagliano, Alessandra Carta, Marcello G. Tanca, Stefano Sotgiu
Summary: Pediatric acute-onset neuropsychiatric syndrome (PANS) is characterized by a constellation of acute symptoms followed by a chronic course. Recent research has focused on clinical and pathophysiological aspects of PANS, as well as strategies for disease management. The importance of a comprehensive approach to treatment and the role of neuro-inflammation in psychiatric disorders are highlighted. This article is rated 7 out of 10 in terms of importance.
NEUROPSYCHIATRIC DISEASE AND TREATMENT
(2023)
Article
Engineering, Multidisciplinary
Lei Zhang, Renhu Liu, Jinling Wu, Zhongtao Cheng, Sheng Zhou, Jingsong Li, Benli Yu
Summary: The FSAI utilizes a mixed SA-HC algorithm for optimization, achieving better convergence than the SPGD algorithm and comparable to the GA algorithm. This approach allows for faster testing of volume-produced optical systems in the optical shop, while simulations and experiments validate its feasibility.
Article
Computer Science, Information Systems
Hisayoshi Muramatsu, Masaki Hino
Summary: This paper introduces the priority control and periodic/aperiodic separation control for realizing multiple tasks in robots. The integration of these two control methods is proposed to increase the number of simultaneously realized tasks. Stability analysis and experiments are conducted to validate the proposed method, which successfully increases the number of realizable tasks from six to nine.
Article
Engineering, Electrical & Electronic
Yang Yang, Minglin Ma, Zhijun Li, Mengjiao Wang, Yichuang Sun, Liang Chen
Summary: This paper investigates the bursting oscillations and formation mechanism of memristive non-smooth systems. It introduces a third-order memristor model and an external periodic excitation into a non-smooth dynamical system to establish a novel 4D memristive non-smooth system with two-timescale. Through the analysis of time series, phase portraits, and bifurcation diagrams, it is found that both the stability of the equilibrium trajectory and the non-smooth interface can influence the bursting phenomenon. The existence of coexisting bimodal periodic oscillations at the non-smooth interface is also observed.
AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS
(2022)
Article
Engineering, Chemical
Mikael Patrik Rimvall, Jens Abildskov
Summary: Simulations and designs are conducted on conventional and periodic SO2 absorption using salt water as solvent for exhaust gases. The advantages of periodic operation, such as shorter towers and less solvent required, are applicable to absorption processes as well.
Article
Biochemical Research Methods
Umer Sajjad, Finn Klingbeil, Findan Block, Rasmus B. Hollander, Shehroz Bhatti, Enno Lage, Jeffrey McCord
Summary: The research focuses on achieving high efficiency separation for biological analytes in biomedical applications by selectively and directionally controlling the movement of microbeads through adjusting magnetic fields. Despite significant size and magnetic content distributions within microbead populations, high separation efficiencies are demonstrated.
Article
Chemistry, Physical
Hong-Zhou Ye, Timothy C. Berkelbach
Summary: This paper presents an efficient implementation of periodic Gaussian density fitting using the Coulomb metric. The method, called range-separated GDF (RSGDF), scales sublinearly to linearly with the number of k-points for small to medium-sized k-point meshes commonly used in periodic calculations with electron correlation. Numerical results show significant speedups with little precision loss compared to previously developed GDF.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Thermodynamics
Navid Freidoonimehr, Azadeh Jafari, Maziar Arjomandi
Summary: In this study, a high-fidelity flow visualisation technique is used to investigate the resemblance between a turbulent boundary layer generated by different tripping devices in a lab environment and a naturally developed canonical turbulent boundary layer. The study finds that the blockage created by trips is the main factor affecting the turbulence statistics at a certain downstream distance.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
Yuning Wang, Alberto Solera-Rico, Carlos Sanmiguel Vila, Ricardo Vinuesa
Summary: This study proposes a method that combines 6-VAEs for modal decomposition and transformer neural networks for temporal-dynamics prediction in the latent space to develop reduced-order models (ROMs) for turbulent flows. The method achieves high reconstruction accuracy and accurate prediction of temporal dynamics.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
L. Laguarda, S. Hickel, F. F. J. Schrijer, B. W. van Oudheusden
Summary: Wall-resolved large-eddy simulations were used to investigate the Reynolds number effects in supersonic turbulent boundary layers at Mach 2.0. The study covered a wide range of friction Reynolds numbers and identified trends in various statistics and scaling laws. The size and topology of turbulent structures in the boundary layer were examined, with a focus on the outer-layer motions at high Reynolds numbers. The study also assessed the influence of outer-layer structures on near-wall turbulence and the sensitivity of uniform momentum regions to compressibility.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
A. Doehring, T. Kaller, S. J. Schmidt, N. A. Adams
Summary: In this study, well-resolved large-eddy simulations were used to investigate turbulent duct flows with a square cross section. The influence of a modified wall shear stress on the secondary flow was analyzed by artificially modifying the wall shear stress at one of the four walls. The results showed that the modification led to an asymmetrical distribution of the secondary flow source terms, affecting the momentum distribution. Furthermore, the anisotropy of the Reynolds stress tensor, which induces the secondary flow vortices, was significantly affected by the wall shear stress modulation.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
