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Sandwich panels with trapezoidal metal/glass fiber cores are increasingly popular due to their lightweight and energy-absorption properties. This study employs response surface methodology (RSM) and Box-Behnken design to investigate the effects of core angle, fiber orientation, and MCM-48 nanoparticles on the panels' energy absorption and peak force, developing regression models with high R2 values of 0.9027 and 0.9228, respectively. Experimental tests were conducted to validate these models, showing minimal deviation from predicted values. Results indicate that increasing the fiber orientation angle from 30° to 90° enhances energy absorption and peak force by 72.18 and 46.9%, respectively, and adding MCM-48 nanoparticles up to 0.25% weight improves energy absorption by 60.8%. A core angle of 52° balances energy absorption and peak force, while integrating a metal wire mesh within the panels significantly enhances energy absorption and reduces core brittleness. The optimal parameters for maximum energy absorption and minimum peak force include a core angle of 58°, fiber orientation of 73.5°, and no nanoparticles. These findings provide valuable insights into the design and optimization of sandwich panels for various applications. [ABSTRACT FROM AUTHOR]

Taking the return-airway 4204 with roof cutting in Longquan Coal Mine as the engineering background, roof structure, key parameters, and deviatoric stress evolution were studied. Conclusion: The Key Stratum within a 4–8 times mining height is considered as Near Key Stratum. Cutting the roof makes it possible to form a cantilever structure of the Key Stratum on the solid coal side, which is more conducive to the stability of gob-side roadway. During cutting angle of 90–55°, the deviatoric stress increases linearly, and the increase rate is coal pillar > solid coal > roof > floor. While cutting length from 0 to 35 m, the deviatoric stress decreases linearly, and the decreasing range: coal pillar > solid coal > roof > floor. When coal pillar width is from 30 to 4 m, the deviatoric stress of left side and floor presents a "single peak" distribution. The deviatoric stress of coal pillar changes from an asymmetric "double peak" to a bell-shaped distribution, and the deviatoric stress of roof changes from a "single peak" to an asymmetric "double peak" distribution. Under same coal pillar width, the deviatoric stress of left, coal pillar and roof after roof cutting decreases most obviously, followed by the floor. Finally, the coal pillar width is 8 m, the cutting angle is 75°, the cutting length is 20 m, and the hole spacing is 1.0 m. The support scheme is bolt + metal mesh + steel belt + anchor cable combined support. The stable period of roadway is about 10 days. [ABSTRACT FROM AUTHOR]

Aiming at the technical problems of frequent dynamic pressure disturbance of regenerated roof and roadway stability control in the process of forming large-section support return channel under the delamination mining, taking 1200-2 fully mechanized caving face of Baiyinhua No. 4 Mine as the engineering background, numerical simulation and theoretical analysis were adopted. The overburden structure of the lower stratified caving face and the loading characteristics of the roof after the expansion are analyzed, and the breaking forms and the limiting conditions of the roof are given.The combined support scheme of anchor rod + metal mesh + steel ladder belt + I-beam insertion + suspension beam + anchor cable + single pillar is studied to form a set of safe and efficient construction support technology system. Practice shows that this scheme can effectively reduce the roof subsidence, narrow the scope of plastic failure zone, and ensure the stability of roadway surrounding rock during the support withdrawal period. Successfully complete the efficient withdrawal of hydraulic support. The research results can provide a good reference for the roof management and the smooth output of coal resources under similar conditions. [ABSTRACT FROM AUTHOR]

This work presents an optically transparent and flexible MIMO antenna that features two square patch elements placed in close proximity, aiming to meet the demands of compactness, flexibility, optical transparency, and visual appeal for IoT applications and future 5G wireless communication. The design includes a simple offset fed configuration to achieve the required isolation and impedance matching. It simplifies the process of creating closely spaced transparent MIMO antenna configurations. By optimizing and analyzing this structure, the antenna achieves better isolation and diversity gain performance, even when the patch elements are positioned very close to each other. To achieve optical transparency and flexibility, the antenna uses thin polyethylene terephthalate (PET) material as a substrate, which is a thermoplastic polymer resin from the polyester family. The wired metal mesh parameters for conducting parts of the MIMO antenna and offset position of the feed are carefully optimized to achieve required optical transparency, isolation, impedance matching and radiation performance without any complex decoupling or impedance matching network. [ABSTRACT FROM AUTHOR]

Ionic polymer-metal composite (IPMC) actuators were prepared with Nafion film as the ionic polymer and gold nanowire (Au-NW) mesh film as the metal electrodes by hot-pressing, which shortened preparation time within 1 h. As a reference, IPMC actuator consisting of Nafion film and gold foil (Au-foil) was also prepared. Au-NW mesh film can be an electrode with thinner (about 150 nm) and lower surface resistivity (about 0.5 Ω sq−1) than the conventional electrode prepared by electroless plating. Larger contact area of the Au-NW mesh electrode than the Au-foil electrode resulted in better actuation performance (60% larger peak-to-peak displacement in actuation). It was confirmed that the transformation behavior of Au-NWs differed depending on the external stimuli condition. Namely Au-NWs transformed to Au nanoparticles in the case of the heat stimulus only. Meanwhile, Au-NWs transformed to plates in the case of the heat and pressure stimuli. While higher temperature improved the adhesion of Au-NW mesh electrode to the Nafion surface, it induced the transformation of nanowire to plates. The IPMC actuator that the Au-NW mesh electrodes were hot-pressed at 90 ºC exhibited the highest capacitance and the largest peak-to-peak displacement in actuation. This research expanded the application field of gold nanowires to the electromechanical devices. [ABSTRACT FROM AUTHOR]

Electrochemical exfoliation of nonconductive boron to few-layered borophene is reported. This unique effect is achieved via the incorporation of bulk boron into metal mesh inducing electrical conductivity and opening a venue for borophene fabrication via this feasible strategy. The experiments were conducted in various electrolytes providing a powerful tool to fabricate borophene flakes with a thickness of ~ 3–6 nm with different phases. The mechanism of electrochemical exfoliation of boron is also revealed and discussed. Therefore, the proposed methodology can serve as a new tool for bulk scale fabrication of few-layered borophene and speed up the development of borophene-related research and its potential application. [ABSTRACT FROM AUTHOR]

An electromagnetic pulse (EMP) with high energy can damage electronic equipment instantly within a wide range of thousands of kilometers. Generally, a metal plate placed inside a thick concrete wall is used against an EMP, but it is not suitable for an EMP shielding window, which requires not only strong shielding effectiveness (SE) but also optical transparency (OT). In this paper, we propose a very thin and optically transparent structure with excellent SE for EMP shielding window application. The proposed structure consists of a saltwater layer held between two glass substrates and two metal mesh layers on the outside of the glass, with a total thickness of less than 1.5 cm. The SE and OT of the structure are above 80 dB and 45%, respectively, which not only meet the requirement of EMP shielding for military purposes but also retain the procedure of good observation. Moreover, the OT of the structure can be significantly improved using only one metal mesh film (MMF) layer, while the SE is still maintained high to satisfy the required SE for home applicants. With the major advantages of low cost, optical transparency, strong SE, and flexible performance, the proposed structure can be considered a good solution for transparent EMP shielding windows. [ABSTRACT FROM AUTHOR]