This paper investigates a 1.7 mm diameter ultra-weak fiber Bragg grating (UWFBG) hydrophone towed array cable for acoustic direction finding. The mechanism of the underwater acoustic waves received ...by this integrated-coating sensitizing optical cable is deduced, and it is shown that the amplitude of its response varies with the direction of the sound wave. An anechoic pool experiment is carried out to test the performance of such a hydrophone array. The test array is a selection of six sensing fibers, each of which is coiled into 9 cm diameter fiber ring suspended in the water to receive acoustic signals. An average sensitivity of −141.2 dB re rad/μPa at frequencies from 2.5 kHz to 6.3 kHz was achieved, validating the detection of the azimuth of underwater acoustic waves. The ultra-thin towing cable system, with free structure, high sensitivity, and underwater target-detection capability has demonstrated great potential for future unmanned underwater vehicle (UUV) applications.
First-principles calculations are performed to study the electronic and magnetic properties of VX2 monolayers (X = S, Se). Our results unveil that VX2 monolayers exhibit exciting ferromagnetic ...behavior, offering evidence of the existence of magnetic behavior in pristine 2D monolayers. Furthermore, interestingly, both the magnetic moments and strength of magnetic coupling increase rapidly with increasing isotropic strain from −5% to 5% for VX2 monolayers. It is proposed that the strain-dependent magnetic moment is related to the strong ionic–covalent bonds, while both the ferromagnetism and the variation in strength of magnetic coupling with strain arise from the combined effects of both through-bond and through-space interactions. These findings suggest a new route to facilitate the design of nanoelectronic devices for complementing graphene.
Modular multilevel converter (MMC) has become a promising topology applied in medium/high-voltage applications due to its advantages. However, there are several challenges in the MMC, such as the ...appearance of harmonic circulating current. In this paper, a novel two-stage model predictive control (TSMPC) is proposed to suppress the harmonic circulating current. First, the mathematical model of the MMC is discretized to describe steady-state objectives including output currents, circulating currents, summation, and imbalance of capacitor voltages. Then, an optimal control options set consisting of inserted numbers is built by the front stage of TSMPC, while the inserted number applied to the MMC ultimately is selected from the above-mentioned set by the back stage of TSMPC. The proposed TSMPC can not only improve the control performance of harmonic circulating current but also ensure the overall control performance of the MMC system. In addition, a simplified rolling optimization method is proposed to reduce computation from the aspect of simplifying each control option prediction. An optimized search space method is also proposed to design the control options set to be evaluated from the aspect of ensuring the output current tracking and harmonic circulating current suppression. Finally, the effectiveness of the proposed method is validated by experiment results.
Main conclusion
NO was involved in H
2
-induced adventitious rooting by regulating the protein and gene expressions of PM H
+
-ATPase and 14-3-3. Simultaneously, the interaction of PM H
+
-ATPase and ...14-3-3 protein was also involved in this process.
Hydrogen gas (H
2
) and nitric oxide (NO) have been shown to be involved in plant growth and development. The results in this study revealed that NO was involved in H
2
-induced adventitious root formation. Western blot (WB) analysis showed that the protein abundances of plasma membrane H
+
-ATPase (PM H
+
-ATPase) and 14-3-3 protein were increased after H
2
, NO, H
2
plus NO treatments, whereas their protein abundances were down regulated when NO scavenger carboxy‐2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (cPTI O) was added. Moreover, the mRNA abundances of the
HA3
and
14-3-3(7)
gene as well as the activities of PM H
+
-ATPase (EC 3.6.1.35) and H
+
pump were in full agreement with the changes of protein abundance. Phosphorylation of PM H
+
-ATPase and the interaction of PM H
+
-ATPase and 14-3-3 protein were detected by co-immunoprecipitation analysis. H
2
and NO significantly up regulated the phosphorylation of PM H
+
-ATPase and the interaction of PM H
+
-ATPase and 14-3-3 protein. Conversely, the stimulation of PM H
+
-ATPase phosphorylation and protein interaction were significantly diminished by cPTIO. Protein interaction activator fusicoccin (FC) and inhibitor adenosine monophosphate (AMP) of PM H
+
-ATPase and 14-3-3 were used in this study, and the results showed that FC significantly increased the abundances of PM H
+
-ATPase and 14-3-3, while AMP showed opposite trends. We further proved the critical roles of PM H
+
-ATPase and 14-3-3 protein interaction in NO–H
2
-induced adventitious root formation. Taken together, our results suggested that NO might be involved in H
2
-induced adventitious rooting by regulating the expression and the interaction of PM H
+
-ATPase and 14-3-3 protein.
Valley, as a new degree of freedom for electrons, has drawn considerable attention due to its significant potential for encoding and storing information. Lifting the energy degeneracy to achieve ...valley polarization is necessary for realizing valleytronic devices. Here, on the basis of first-principles calculations, we show that single-layer FeCl2 exhibits a large spontaneous valley polarization (∼101 meV) arising from the broken time-reversal symmetry and spin-orbital coupling, which can be continuously tuned by varying the direction of magnetic crystalline. By employing the perturbation theory, the underlying physical mechanism is unveiled. Moreover, the coupling between valley degree of freedom and ferromagnetic order could generate a spin- and valley-polarized anomalous Hall current in the presence of the in-plane electric field, facilitating its experimental exploration and practical applications.
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In this work, we present the numerical dispersion and dissipation analyses of the triangle-based discontinuous Galerkin method (DGM) for acoustic and elastic velocity-stress equations. The analysis ...is based on the eigenvalue problem. The applicability of the flux-based DGM is affected by many factors, including numerical flux, basis function, mesh element, and time-stepping scheme. Based on the semi-discrete analysis, we compare different numerical fluxes—Centred flux, local Lax-Friedrichs (LLF) flux, and Godunov flux, different basis functions—Koornwinder-Dubiner (KD) polynomial, Legendre polynomial, and simple monomial function, and four types of triangular meshes. The fully discrete schemes include the third-order total variation diminishing Runge-Kutta (TVD RK) method and the third-order weighted Runge–Kutta (WRK) method. The results indicate that numerical dispersion and dissipation behave differently for different numerical fluxes and mesh types, which verifies the importance of considering numerical fluxes and mesh types. We find that using LLF and Godunov fluxes, and the mesh pattern of case 3 has attractive advantages for numerical simulation. The result of the dispersion-dissipation analysis with different basis functions demonstrates that for high-order integral accuracy, three kinds of basis functions have the same performance in suppressing numerical dispersion and dissipation in triangular elements. The fully discrete dispersion–dissipation analysis shows that the time-stepping scheme introduces numerical dispersion and dissipation and the fully discrete case with a small sampling ratio and Courant number has a better effect in suppressing numerical dispersion and dissipation. Finally, we provide several numerical experiments to validate our theoretical finding, and numerical results are consistent with theoretical dispersion-dissipation analyses.
•Numerical dispersion and dissipation in a triangular element are presented.•The velocity-stress equations are firstly used to analyzed.•Different factors for dispersion-dissipation analysis are fully considered.•Mesh can cause in the numerical anisotropic behavior.•Numerical experiments are consistent with our theoretical analysis.
Manipulating the valley degree of freedom as an information carrier has been a focused topic for both fundamental and applied research. Here, using first-principles calculations, we report the ...identification of monolayer CrX2 (X = S, Se) as a novel two-dimensional valleytronic crystal. It shows large valley spin splitting in the valence band, attractive for the integration of valleytronics and spintronics. More importantly, through proximity coupling with monolayer CrCl3, the valley polarization in monolayer CrX2 is achieved, which can be further engineered by stacking patterns. Also, the valley polarization in monolayer CrX2 can be obtained via magnetically doping V and Mn. Specially for V-doped monolayer CrSe2, there are no impurity states in the band gap, beneficial for its practical applications. Our works thus provide not only exceptional two-dimensional valleytronic crystals but also promising ways for realizing valley polarizations in them.
Wire-arc directed energy deposition (wire-arc DED), recognized for its ability to produce large-scale parts, has gained considerable attention. However, a critical issue with this method is the high ...prevalence of internal porosity defects found in the manufactured aluminum components, adversely impacting their mechanical properties. For the first time, this study introduces in-situ interlayer Laser Shock Peening (LSP) during wire-arc DED of 2319 aluminum alloy. The thickness of each deposited layer was meticulously regulated within the 0.7–1.3 mm range utilizing a spiral-path oscillation mode. Following this process, LSP was applied to the top surface of each layer. Compared to the as-deposited samples, interlayer LSP-treated samples showed a significant decrease in pore numbers by 73.9% and a reduction in the total area by 87.4%.
Furthermore, the LSP-treated samples displayed improved mechanical properties with increases in ultimate tensile strength, yield strength, and elongation by 20.1%, 19.1%, and 27.3%, respectively. The primary impact of LSP on the microstructure is the generation of high-density dislocations, providing a driving force for grain refinement during subsequent layer heat input. With the combined effects of heat input and dislocation density, samples treated with LSP form a tight metallurgical bound around the closed pores. This process of effective defect elimination and an increased dislocation density between the layers results in a simultaneous improvement in strength and plasticity.
Van der Waals heterostructures (vdWHs) are attracting a lot of interest for fundamental studies and fabricating novel devices. Currently, most vdWHs exhibit type-I or type-II band alignment, and few ...systems have been shown to be in the type-III class. Herein, we show first-principles evidence that WTe2/HfS2 vdWH possesses the long-sought type-III band alignment with a broken gap, providing a promising platform for developing tunnel field-effect transistors. Moreover, the electronic features of WTe2/HfS2 vdWH can be effectively modulated via external strain and electric field. Particularly, an interesting transition from type-III to type-II band alignment can be observed in WTe2/HfS2 vdWH upon the application of strain or electric field, which holds great potential for designing multifunctional devices. Our study not only predicts an extraordinary vdWH with type-III band alignment but also provides an outstanding candidate for realizing multiple band alignment transformation.
Abstract Background Increased intake of specific vitamins has been linked to a decreased prevalence of osteoporosis. However, the association between dietary folate intake and the risk of ...osteoporosis in the general population remains incompletely understood. Therefore, we aimed to determine the association between dietary folate intake and the risk of osteoporosis in the general population of the USA. Methods In this cross-sectional study, data from the National Health and Nutrition Examination Survey (2017–2020) were collected. Osteoporosis was considered to be indicated by a bone mineral density greater than 2.5 standard deviations below the mean of the young adult reference group. Dietary folate intake was measured by a 24-hour dietary recall. Multivariate logistic regression models and restricted cubic spline models were used. Results The study included 2297 participants (mean age: 63.69 ± 0.35 years), 49.92% of whom were female. In the general population, increased dietary folate intake was directly associated with a decreased risk of osteoporosis ( P for trend = 0.005). In the age > 60 years and female subgroups, folate intake was inversely associated with the risk of osteoporosis ( P for trend < 0.001). The dose‒response curve suggested that this association was nonlinear ( P for nonlinearity = 0.015). Conclusions Our cross-sectional study provides initial insights into the inverse association between dietary folate intake and the risk of osteoporosis in the general U.S. population. Further research is needed to confirm these associations.
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