Article
Mechanics
A. Chiarini, M. Quadrio, F. Auteri
Summary: This study investigates the primary instability of flow past rectangular cylinders, analyzing the influence of aspect ratio and rounded corners on stability. It is found that the critical Reynolds number increases with aspect ratio, and the presence of small circular cylinders in the flow can modify instability significantly. Rounded corners affect the primary instability in a manner dependent on both aspect ratio and curvature radius, with differing effects on stability based on the location and curvature of the corners.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Negar Hosseini, Martin D. Griffith, Justin S. Leontini
Summary: The study shows that when the pitch between two upstream cylinders is large, the downstream wake exhibits a two-row vortex structure, and the shape of the third body has minimal impact on this structure. However, in certain cases, the position of the third body can disrupt the original vortex structure and globally broadcast its presence.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Multidisciplinary
Marek Dobosz, Michal Jankowski
Summary: A new absolute sensor design for measuring angular micro-displacement uses changes in interference fringes to determine measurements with an uncertainty of +/-10 grad. The concept of a two-sensor system is introduced to double the measuring range.
PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY
(2021)
Article
Mechanics
Alessandro Chiarini, Maurizio Quadrio, Franco Auteri
Summary: The three-dimensional instability of the flow past a 5:1 rectangular cylinder is investigated using Floquet analysis and direct numerical simulations. A quasi-subharmonic unstable mode is found to become unstable at Reynolds number Re≈480, with a spanwise wavelength approximately three times the cylinder thickness. The structural sensitivity analysis reveals that the instability is triggered by the mutual inviscid interaction of vortices generated by the leading edge shear layer.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Alessandro Chiarini, Franco Auteri
Summary: The primary instability of steady two-dimensional flow past rectangular cylinders moving parallel to a solid wall is investigated, considering the cylinder length-to-thickness aspect ratio AR and the dimensionless distance from the wall g. Two types of primary instability are identified: a Hopf bifurcation leading to unsteady two-dimensional flow for g >= 0.5, and a regular bifurcation leading to steady three-dimensional flow for g < 0.5. The critical Reynolds numbers for both bifurcations depend on the gap height and aspect ratio, and exhibit different trends for different conditions.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Engineering, Multidisciplinary
D. Mari, M. Pisani, M. Astrua, M. Zucco, S. Pasqualin, A. Egidi, M. Bertinetti, A. Barbone
Summary: A novel optical pressure standard based on an unbalanced homodyne interferometer is introduced, which can measure the refractive index of a gas. The interferometer has one arm formed by a multi-reflection double mirror assembly, enabling an unbalance length larger than 6 m in a compact setup. The paper discusses the crucial steps in realizing this method, including estimating the pressure-induced deformation, temperature control at millikelvin level, and measuring the interferometer unbalance in vacuum. The evaluation shows that the realized optical pressure standard can measure pressure with a relative uncertainty of 10 ppm at 100 kPa.
Review
Physics, Multidisciplinary
Giulio Gasbarri, Alessio Belenchia, Matteo Carlesso, Sandro Donadi, Angelo Bassi, Rainer Kaltenbaek, Mauro Paternostro, Hendrik Ulbricht
Summary: Space technology offers current and future possibilities for testing quantum mechanics, with a focus on mesoscopic superposition of nanoparticles and interferometric experiments in space. Quantum technologies are rapidly advancing applied and fundamental science, with promises of exploring new physics through the combination of quantum technologies and space science. Understanding the superposition principle of quantum mechanics and the quantum-to-classical transition through studies of mesoscopic superpositions of nanoparticles and interferometric experiments has the potential to test quantum mechanics at an unprecedented level.
COMMUNICATIONS PHYSICS
(2021)
Article
Engineering, Multidisciplinary
Shuai Xue, Lingwei Kong, Yifan Dai, Shanyong Chen, Zhifan Lin
Summary: The near-null interferometric test method for aspheric cylinders using a partial null lens and a coaxial configuration design allows for testing various aspheric cylinders with high accuracy in optical design. The proposed method provides easier test accuracy guarantee compared to existing methods, and the testability results can serve as a guide for engineers designing high-energy laser systems. The established near-null test system demonstrates simple configuration, moderate accuracy, and flexible test capacity for measurements on aspheric cylinders.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2021)
Article
Mathematics
Edward McDonald, Fedor Sukochev
Summary: We study a class of real functions satisfying Lipschitz estimates in the Schatten ideal L-p for 0 < p <= 1, using wavelet analysis techniques. We prove that Lipschitz functions belonging to the homogeneous Besov class satisfy certain estimates, and provide counterexamples to a conjecture regarding Lipschitz functions in L-p for 0 < p < 1.
MATHEMATISCHE ANNALEN
(2022)
Article
Engineering, Multidisciplinary
Zhiqi Xie, Yang Liu, Jianshuang Li, Ruixue Zhang, Mingzhao He, Dongjing Miao, Shiying Cao, Jiusun Zeng, Jinhui Cai, Jiaxiang Zhu
Summary: This paper investigates the influence of spectral bandwidth on the precision of distance measurement in time-of-flight dual-comb ranging. The study presents a numerical simulation method to analyze the ranging results and identifies the optimal bandwidth range. Experimental results confirm the simulation findings and show that narrow spectral bandwidth improves system stability within the optimal precision range.
Article
Optics
Zhiyao Ma, Donghui Zheng, Lei Chen, Ruokun Li, Chenhui Hu, Zhe Zhang, Jun Ma
Summary: A novel absolute measurement method using two plates based on odd-even functions is proposed. Compared to existing methods, this method is simpler and does not require additional measurement of refractive index uniformity. The feasibility and accuracy of the method are demonstrated through simulations and experiments.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Geochemistry & Geophysics
Yunqiao He, Fan Gao, Tianhe Xu, Xinyue Meng, Nazi Wang
Summary: Global navigation satellite system reflectometry has the potential to provide high-precision sea surface height measurements. This study proposes a coastal GNSS-R altimetry algorithm using signals from the Quasi-Zenith Satellite System GEO satellite to overcome the issue of phase unwrapping errors. Experimental results show that the algorithm achieves accurate sea level estimation with a root mean square error of 1.4 cm.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2022)
Article
Engineering, Multidisciplinary
Jose Humberto S. Almeida, Luc St-Pierre, Zhihua Wang, Marcelo L. Ribeiro, Volnei Tita, Sandro C. Amico, Saullo G. P. Castro
Summary: This work demonstrates the potential of manufacturing variable-angle composite cylinders using filament winding. The approach allows different filament angles along the axial direction by dividing the cylinder into regions of constant angle. The VAFW design shows significantly higher buckling strength, stiffness, and absorbed energy compared to the constant-angle configuration.
COMPOSITES PART B-ENGINEERING
(2021)
Article
Optics
Shuai Xue, Yifan Dai, Shengyue Zeng, Shanyong Chen, Ye Tian, Feng Shi
Summary: A new interferometric stitching method for testing cylindrical surfaces with large apertures was proposed to overcome limitations of traditional methods, along with the development of a subaperture stitching algorithm for stitching along linear and arc directions. The proposed method was validated on a convex cylindrical surface with a significantly enlarged aperture, promoting the application of large cylindrical surfaces in high-energy laser systems.
Article
Geosciences, Multidisciplinary
Dandan Tao, Robert Nystrom, Michael Bell
Summary: The low-level tangential wind structure of tropical cyclones is important for risk assessment, but there is still a need for a realistic and easy-to-implement model. This study proposes an empirical approach to obtain an inner-core wind structure model that reduces the complexity of tropical cyclone wind profiles. Idealized simulations show that the absolute angular momentum outside the radius of maximum wind has a quasi-linear relationship, with the slope decreasing with cyclone intensity. The linear momentum slope wind model can accurately capture the inner-core wind structure and has potential for practical applications.
GEOPHYSICAL RESEARCH LETTERS
(2023)
