The mixing of two co-directional, initially monochromatic Rayleigh surface waves in an isotropic, homogeneous, and nonlinear elastic solid is investigated using analytical, finite element method, and experimental approaches. The analytical investigations show that while the horizontal velocity component can form a shock wave, the vertical velocity component can form a pulse independent of the specific ratios of the fundamental frequencies and amplitudes that are mixed. This analytical model is then used to simulate the development of the fundamentals, second harmonics, and the sum and difference frequency components over the propagation distance. The analytical model is further extended to include diffraction effects in the parabolic approximation. Finally, the frequency and amplitude ratios of the fundamentals are identified which provide maximum amplitudes of the second harmonics as well as of the sum and difference frequency components, to help guide effective material characterization; this approach should make it possible to measure the acoustic nonlinearity of a solid not only with the second harmonics, but also with the sum and difference frequency components. Results of the analytical investigations are then confirmed using the finite element method and the experimental feasibility of the proposed technique is validated for an aluminum specimen.
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http://dx.doi.org/10.1121/1.4904535 | DOI Listing |
Nat Mater
January 2025
State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai, China.
Polymorphism, commonly denoting diverse molecular or crystal structures, is crucial in the natural sciences. In van der Waals antiferromagnets, a new type of magnetic polymorphism arises, presenting multiple layer-selective magnetic structures with identical total magnetization. However, resolving and manipulating such magnetic polymorphs remain challenging.
View Article and Find Full Text PDFJ Speech Lang Hear Res
January 2025
Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston.
Purpose: The Daily Phonotrauma Index (DPI) can quantify pathophysiological mechanisms associated with daily voice use in individuals with phonotraumatic vocal hyperfunction (PVH). Since DPI was developed based on weeklong ambulatory voice monitoring, this study investigated if DPI can achieve comparable performance using (a) short laboratory speech tasks and (b) fewer than 7 days of ambulatory data.
Method: An ambulatory voice monitoring system recorded the vocal function/behavior of 134 females with PVH and vocally healthy matched controls in two different conditions.
Dalton Trans
January 2025
School of Chemistry and Chemical Engineering, Nanchang University, Nanchang, 330031, People's Republic of China.
Three-component crown ether phase change materials are characterized by a structural phase change in response to external stimuli such as temperature and electric or magnetic fields, resulting in significant changes in physical properties. In this work, we designed and synthesized two novel host-guest crown ether molecules [(PTFMA)(15-crown-5)ClO] (1) and [(PTFMA)(15-crown-5)PF] (2), through the reaction of -trifluoromethylaniline (PTFMA) with 15-crown-5 in perchloric acid or hexafluorophosphoric acid aqueous solution. Compound 1 undergoes a structural change from the non-centrosymmetric space group (2) to the centrosymmetric space group (2/) with increasing temperature.
View Article and Find Full Text PDFDalton Trans
January 2025
State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430200, China.
The quest for novel nonlinear optical (NLO) polymorphs is pivotal for advancing laser technology and frequency conversion applications. We present a detailed study on the synthesis and properties of the 2 polymorph of CHNOZn, which exhibits an enhanced second harmonic generation (SHG) effect, 0.3 times that of KDP, nearly 8-fold higher than the 422 phase.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
December 2024
Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, 2, Dublin, Ireland; Discipline of Mechanical, Manufacturing, and Biomedical Engineering, School of Engineering, Trinity College Dublin, 2, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin, Ireland. Electronic address:
Aortic stenosis is a prevalent disease that is treated with either mechanical or bioprosthetic valve replacement devices. However, these implants can experience problems with either functionality in the case of mechanical valves or long-term durability in the case of bioprosthetic valves. To enhance next generation prosthetic valves, such as biomimetic polymeric valves, an improved understanding of the native aortic valve leaflet structure and mechanical response is required to provide much needed benchmarks for future device development.
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