Multimodal ultrasonic vibration (UV) assisted micro-forming has been widely investigated for its advantages of further reducing forming loads and improving forming quality. However, the influence mechanism of different UV modes on microstructure evolution and mechanical properties was still unclear. Multimodal UV assisted micro-compression tests on T2 copper with different grains and sample sizes were conducted in this study. The microstructure evolution for different UV modes was observed by EBSD. The results showed that the true stress reduction caused by UV was increased sequentially with tool ultrasonic vibration (TV), mold ultrasonic vibration (MV) and compound ultrasonic vibration (CV). The region of grain deformation was shifted along the direction of UV, and the MV promoted the uniform distribution of deformation stress. The grain refinement, fiber streamline density, grain deformation and rotation degree were further enhanced under CV, due to the synergistic effect of TV and MV. Additionally, a coupled theoretical model considering both acoustic softening effect and size effect was proposed for describing the mechanical properties. And a physical model of dislocation motion in different UV modes was developed for describing the microstructure evolution. The maximum error between the theoretical and experimental results was only 2.39 %. This study provides a theoretical basis for the optimization of UV assisted micro-forming process.

Efficient bone milling processes, producing high-quality machined surfaces, are crucial for enhancing arthroplasty surgery. This study introduces a novel Longitudinal Torsional Ultrasonically Vibration Milling (LTVUM) technique and conducts a comparative analysis with Conventional Milling (CM). The reduction in average milling force observed during the LTVUM process was systematically recorded. Orthogonal experimental analysis focusing on milling orientation, rotational speed, and feed velocity revealed that LTVUM diminishes the influence of orientation and rotational speed, while amplifying the impact of feed velocity. Subsequent response surface methodology experiments further demonstrated that LTUVM significantly augmented the impact of integrated parameters related to feed velocity. Moreover, LTVUM was found to improve machining surface quality and alter the shear mode. These results have profound implications for the theoretical exploration of LTVUM, supporting the design and development of innovative tools for arthroplasty surgery.

Metal-based loudspeaker diaphragms show promise for high-frequency audio devices, but they produce sharp and fatiguing sounds. This study aimed to improve high-frequency response by depositing a durable diamond-like carbon (DLC)/W coating on aluminum‑magnesium (Al-Mg) diaphragms. The effect of PECVD deposition bias voltage on the coating's morphology, chemical structure, and mechanical properties was investigated. W-based intermediate layer boosted DLC-substrate adhesive strength by 2.5 times compared to direct DLC deposition. The nanohardness, elastic modulus, and Vickers hardness of DLC/W-coated diaphragms initially increased and then decreased with bias voltage (−100 to −300 V), peaking at −200 V, correlating with sp3 bond content. Compared to uncoated samples, the DLC/W-coated Al-Mg diaphragm loudspeakers expanded bandwidth by 2–5 kHz, improved performance gain by 3.5 dB, suppressed harmonic distortion to <6%, and enhanced subjective auditory experience. These findings hold potential for practical applications, advancing high-frequency loudspeaker technology.

Optical thermometry has gained significant attention due to its remarkable sensitivity and noninvasive, rapid response to temperature changes. However, achieving both high absolute and relative temperature sensitivity in two-dimensional perovskites presents a substantial challenge. Here, we propose a novel approach to address this issue by designing and synthesizing a new narrow-band blue light-emitting two-dimensional perovskite named (C8H12NO2)2PbBr4 using a straightforward solution-based method. Under excitation of near-ultraviolet light, (C8H12NO2)2PbBr4 shows an ultranarrow emission band with the full width at half-maximum (FWHM) of only 19 nm. Furthermore, its luminescence property can be efficiently tuned by incorporating energy transfer from host excitons to Mn2+. This energy transfer leads to dual emission, encompassing both blue and orange emissions, with an impressive energy transfer efficiency of 38.3%. Additionally, we investigated the temperature-dependent fluorescence intensity ratio between blue emission of (C8H12NO2)2PbBr4 and orange emission of Mn2+. Remarkably, (C8H12NO2)2PbBr4:Mn2+ exhibited maximum absolute sensitivity and relative sensitivity values of 0.055 K-1 and 3.207% K-1, respectively, within the temperature range of 80-360 K. This work highlights the potential of (C8H12NO2)2PbBr4:Mn2+ as a promising candidate for optical thermometry sensor application. Moreover, our findings provide valuable insights into the design of narrow-band blue light-emitting perovskites, enabling the achievement of single-component dual emission in optical thermometry sensors.

The processes of ocean dynamics are complex near the Pearl River Estuary and are not clear due to a lack of abundant observations. The spatial characteristics of the spring sea surface currents in the adjacent waters of the Pearl River Estuary were analyzed using the current data observed by a three-station high-frequency surface wave radar system (HFSWRS). Compared with the two-station HFSWRS, the deviation of current velocity and direction observed by the three-station HFSWRS from the underway measurements decreased by 42.86% and 38.30%, respectively. The analyzed results show that the M2 tidal current is the dominant current among all the tidal constituents, followed by K1, with angles of inclination ranging from 130° to 150°. The tidal flow is dominated by northwest–southeast back-and-forth flow. In the southern part of the observed area, which is far from the coastline, the tidal current ellipses exhibit a circular pattern. The prevalent tidal current type in this region is irregularly semi-diurnal, and the shallow water constituents also have a significant effect. The tidal energy in the adjacent waters of the Pearl River Estuary is affected by potential energy flux and kinetic energy flux. As the water depth and currents velocity increase in the southeast direction, the tidal energy flux increases. In the nearshore zone, the direction of tidal energy flux varies along the coastline. The changes in the residual current within the observed area are correlated with the sea surface wind field. Based on the high-precision sea surface current observed by the three-station HFSWRS, the characteristics of the ocean dynamic processes near the Pearl River Estuary are analyzed comprehensively, which provides important reference and confidence for the application of the developing new radar observing network with about 10 radar stations near the Pearl River Estuary.

Ti-6Al-4 V titanium alloy (TC4) and carbon fiber reinforced resin matrix composites (CFRTP) were successfully connected by laser welding after adding PA6 or epoxy as the interlayer. Experiments and simulations were performed to clarify the influence of the interlayers on the joint characteristics, including the strength, interfacial microstructure, failure behavior and joining mechanism under different laser heat inputs (LHI). The results showed that with the increasing heat inputs, the joint strength first increased and then decreased in accordance with the degree of melting/decomposition of the PA6/epoxy interlayer. When the interlayer was PA6, the highest tensile strength of 3428 N was generated under 38.5 J/mm. When the interlayer was epoxy, the highest tensile strength of 3855 N was generated under 45 J/mm. For each interlayer, there was an optimal LHI, when the LHI was lower than the optimal value, the interlayer was not completely melted; Otherwise, the high temperature at the interface can easily damage the CFRTP. All joints regardless of the types of interlayer demonstrated three fracture modes. Both the PA6 and epoxy interlayers can improve the heat distribution on surface of the CFRTP, leading to an increase in melting zone of the resins and thus a joint strength improvement.

Solitary waves are usually used as extreme waves, but their hydrodynamic characteristics differ from those of real-world tsunami waves. N-shaped waves may be used to give a more realistic approximate outline of the tsunami wave. According to this theory and the record of the 2011 Tohoku tsunami wave, the theoretical formulas for the complete tsunami wave based on the superposition of twelve sech2(*) waves are proposed in this study. Moreover, this tsunami wave, which is called the complete tsunami-like wave (CTW), is numerically simulated. The effects of the complete tsunami-like wave are different from those of the solitary wave in the scope of time and space. Since submarine pipelines are easily damaged when exposed to the marine environment, the hydrodynamic characteristics of the complete tsunami-like and solitary waves impacting the tandem pipeline are analyzed and compared. In addition, the interactions between the complete tsunami-like waves with different wave heights and the tandem pipelines with different diameters, distances and locations are investigated. The results show that the effects of the wake wave part of the tsunami wave on the pipeline are still too serious to be ignored. With the increase in the wave height, the loads on the pipeline under the CTW increase. When the pipeline structure changes, the hydrodynamic characteristics and loads are also different. It is anticipated that these findings can help improve the understanding of tsunami waves in the real world.

Shelling with chalcogenides on the surface of lead halide perovskite (LHP) nanocrystals (NCs) is believed to be an effective approach to increase their stability under high-moisture/aqueous conditions, which is important for LHP NC-based optoelectronic devices. However, it is still a challenge to prepare high-quality LHP/chalcogenide core/shell NCs with moisture/aqueous stability. In this work, a surface-defect-induced strategy is carried out to facilitate the adsorption of Br- ions and subsequently Zn2+ ions to preform a bipolar surface, which reduces the energy barrier at the CsPbBr3/ZnS interface and promotes the epitaxial growth of the ZnS shell layer. The aqueous stability of the as-received NCs shows an increase of over 12 times compared to that of the original one. Likewise, Mn2+ ions are introduced to further reduce the geometric symmetry mismatch and defect density at the CsPbBr3/ZnS interface. Interestingly, aqueous stability characterizations illustrate negligible degradation even after 230 min of ultrasonication, suggesting their outstanding stability. This work proposes an effective approach to prepare high-quality LHP/chalcogenide core/shell NCs, which possess great potential in the fabrication of stable optoelectronic devices.

Synthesis of upconversion nanoparticles (UCNPs)-metal halide perovskites (MHPs) heterostructure is garnered immense attentions due to their unparalleled photophysical properties. However, the obvious difference in their structural forms makes it a huge challenge. Herein, hexagonal β-NaYF4 and hexagonal Cs4PbBr6 are filtrated to construct the UCNP/MHP heterostructural luminescent material. The similarity in their crystal structures facilitate the heteroepitaxial growth of Cs4PbBr6 on the surface of β-NaYF4 NPs, leading to the formation of high-quality β-NaYF4:Yb,Tm/Cs4PbBr6 core/shell nanocrystals (NCs). Interestingly, this heterostructure endows the core/shell NCs with typically narrow-band green emission centered at 524nm under 980nm excitation, which should be attributed to the Förster resonance energy transfer (FRET) from Tm3+ to Cs4PbBr6. It is noteworthy that the FRET efficiency of β-NaYF4:Yb,Tm/Cs4PbBr6 core/shell NCs (58.33%) is much higher than that of the physically mixed sample (1.84%). In addition, the reduced defect density, lattice anchoring effect, as well as diluted ionic bonding proportion induced by the core/shell structure further increase the excellent water-resistance and thermal cycling stability of Cs4PbBr6. These findings open up a new way to construct UCNP/MHP heterostructure with better multi-code luminescence performance and stability and promote its wide optoelectronic applications.

Trench and burial, as a primary and effective protection measurement for offshore pipelines from impact loads, has received much research attention recently. Previous studies were usually performed based on the assumption that the soil material was homogeneous with deterministic mechanical properties. The soil spatial variability, which is demonstrated to have significant influences on the soil capacity in marine geotechnical analysis, has not been included. This study was motivated to investigate the response of the buried pipelines subjected to the impact loads, with special address on the soil variability. Firstly, a three-dimensional random large deformation finite element analysis model was developed, which was implemented by the field variable (FV) technique to map the non-stationary random field (NSRF) into the verified Coupled Eulerian-Lagrangian (CEL) model (Hereafter referred to as FVRCEL). Then the FVRCEL model was integrated with the Monte-Carlo simulation (MCS) to obtain the statistical characteristics of the pipeline structural response. The failure mechanisms of the pipeline in the random soil with different fluctuation scales were investigated, and a parametric study was performed to identify the influential factors. Finally, the failure probability curves and surfaces were presented, providing clues for the pipeline safety design. The results revealed that in general, more than 50 % of the realized NSRF scenarios in the random analysis yielded more severe dent damage than the deterministic result, indicating that the latter would underestimate the damage degree, which was more pronounced when the increasing gradient of soil strength was high. The horizontal fluctuation scale had a remarkable influence on the pipeline damage behaviours and the corresponding statistical characteristics, of which the inner mechanisms were discussed. From the probabilistic perspective, at most an extra failure probability of 75 % would be suffered if the soil variability was ignored.