Axial Coupling Research Articles

High coupling efficiency with large axial direction coupling adjustment range in water-jet guided laser

In the traditional water-jet guided laser (WJGL) processing system, convex lens is used to focus Gaussian laser beam, where the waist and divergence angle are constrained. The focal depth is small, and there are problems such as divergence angle and aberration, which results in the difficult coupling adjustment because the adjustment range of laser coupling to water-jet fiber is limited to the Rayleigh range. In this study, non-diffraction laser (NDL) is generated by an axicon, which has the characteristics of small central spot and large non-diffraction range (NDR). The axial random coupling is realized in the NDR, and the problem of axial coupling between the focused laser and the water-jet generated by nozzle micro-hole is solved. Besides, this paper presents a novel technique to generate NDL by the combination of concave axicon (CCA) and convex axicon (CVA), which solves the small cone angle of the single CVA and the non-modulation defect of the corresponding optical and mechanical structure, and extends the starting point of the NDR to improve the coupling utilization rate of the NDR and the flexibility of the system. The focusing and coupling transmission characteristics of convex lens and axicons mode in WJGL are compared and analyzed. The generated NDL in the NDR at the axial reference coordinate point position of 50 mm and 70 mm is successfully coupled into the water-jet fiber. After the coupling transmission of 20 mm, the coupling efficiency, the morphology of the transmitted spot and the peak power density were basically the same, and the coupling efficiency of the central spot was about 81 %. However, the output spot peak power density and coupling efficiency decrease sharply when the axial coupling deviation exceeds 5 mm adopting convex lens. In contrast, the NDL can achieve a random coupling with high axial coupling tolerance in NDR. The research provides a solution for efficient adjustment and transmission of laser coupling into water-jet in highly stable WJGL.

Simultaneous Measurement of the Half-Life and Spectral Shape of ^{115}In β Decay with an Indium Iodide Cryogenic Calorimeter.

Current bounds on the neutrino Majorana mass are affected by significant uncertainties in the nuclear calculations for neutrinoless double-beta decay. A key issue for a data-driven improvement of the nuclear theory is the actual value of the axial coupling constant g_{A}, which can be investigated through forbidden β decays. We present the first measurement of the 4th-forbidden β decay of ^{115}In with a cryogenic calorimeter based on indium iodide. Exploiting the enhanced spectrum-shape method for the first time to this isotope, our study accurately determines simultaneously spectral shape, g_{A}, and half-life. The interacting shell model, which best fits our data, indicates a half-life for this decay at T_{1/2}=(5.26±0.06)×10^{14} yr.

Scalar perturbations from inflation in the presence of gauge fields

We study how Abelian-gauge-field production during inflation affects scalar perturbations in the case when the gauge field interacts with the inflaton directly (by means of generic kinetic and axial couplings) and via gravity. The homogeneous background solution is defined by self-consistently taking into account the backreaction of the gauge field on the evolution of the inflaton and the scale factor. For the perturbations on top of this background, all possible scalar contributions coming from the inflaton, the metric, and the gauge field are considered. We derive a second-order differential equation for the curvature perturbation, ζ, capturing the impact of the gauge field, both on the background dynamics and on the evolution of scalar perturbations. The latter is described by a source term in the ζ equation, which is quadratic in the gauge-field operators and leads to non-Gaussianities in the curvature perturbations. We derive general expressions for the induced scalar power spectrum and bispectrum. Finally, we apply our formalism to the well-known case of axion inflation without backreaction. Numerical results show that, in this example, the effect of including metric perturbations is small for values of the gauge-field production parameter ξ>3. This is in agreement with the previous results in the literature. However, in the region of smaller values, ξ≲2, our new results exhibit order-of-unity deviations when compared to previous results. Published by the American Physical Society 2024

Nuclear medium meson structures from the Schwinger proper-time Nambu–Jona-Lasinio model

In this paper, we report the results of our study on the nuclear medium modifications of the meson electromagnetic form factors in the framework of the Nambu–Jona-Lasinio model with the help of the Schwinger proper-time regularization scheme to tame the loop divergence and simulate the effect of QCD confinement. In our current approach, the meson structure and nuclear medium are constructed in the same Nambu–Jona-Lasinio model at the quark level. We examine the free-space and in-medium charge radii of kaon and pion, the spacelike elastic electromagnetic form factors of kaon and pion, and their quark-sector form factors, which reflect their internal structures. By comparing our result to experimental data, we found that the free-space elastic electromagnetic form factors of the mesons are consistent with the data, while the in-medium elastic electromagnetic form factors of the mesons are found to decrease as the nuclear matter density increases, leading to a rise of meson charge radius, which is consistent with the prediction of other theoretical calculations. We also predict the axial nucleon coupling constant gA in nuclear medium computed via the Goldberger-Treiman relation, which is crucial for searching the neutrinoless double beta decay (0νββ). Published by the American Physical Society 2024

Searching for a new light gauge boson with axial couplings in muon beam dump experiments

We present a formalism for new U(1) interactions involving weak hypercharge, baryon, and lepton numbers, and a possible axial symmetry generator FA in the presence of a second Brout-Englert-Higgs doublet. The resulting U boson, after mixing with the Z, interpolates between a generalised dark photon, a dark Z, and an axially coupled gauge boson. We especially focus on the axial couplings originating from FA or from mixing with the Z, determined by the scalar sector via parameters like tan β and the v.e.v. of an extra dark singlet.We explore the distinctive features of axially coupled interactions, especially in the ultrarelativistic limit, where the U boson behaves much as an axion-like particle, with enhanced interactions to quarks and leptons. This enhancement is particularly relevant for future muon beam dump experiments, since the muon mass considerably increases the effective coupling, proportional to 2mμ/mU, compared to analogous experiments with electrons.We also analyse the shape of the expected beam dump exclusion or discovery regions, influenced by U boson interactions and the experiment geometry. Different situations are considered, limited in particular by cases for which the U decays before reaching the detector, or has too small couplings to produce detectable events. We also compare to vectorially coupled bosons and axion-like pseudoscalars, highlighting the importance of understanding the parameter space for future experiment design and optimisation.

Research progress on freeze–thaw constitutive model of concrete based on damage mechanics

Abstract In cold areas, freeze–thaw damage seriously affects the long-term use and safe operation of concrete structures. The constitutive model is an important foundation for predicting deformation and strength characteristics of concrete materials and for the non-linear analysis of concrete structures. This study is based on the elaboration of methods for the constitutive model of damaged materials by using damage mechanics and others. This study focuses on the existing constitutive model results of concrete under the static axial compression load, dynamic load, and coupling environmental load, and analyzing the problems in existing studies. Research has shown that segmented models exhibit higher fitting accuracy of concrete freeze–thaw constitutive model under static axial compression loads. By defining coupled damage variables, it is possible to approach the actual freeze–thaw damage of concrete under environmental coupling, and attention should be paid to the differences or interactions between damage factors. In order to meet the actual engineering needs of high altitude and cold areas needs to expand the temperature range of freeze–thaw tests and consider the dynamic loads impact on concrete damage, the establishment of constitutive model of concrete under the actual freeze–thaw damage is the focus of frost-resistant durability research of hydraulic concrete in cold regions.

Seismic performance analysis and control method of composite coupled shear wall with steel plate-fiber reinforced concrete coupling beams

This paper based on the study of steel plate-fiber reinforced concrete coupling beam components, designs a basic model of composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams. The seismic performance of this model was numerically simulated using the ABAQUS finite element software, analyzing the stress distribution of various parts and the development pattern of plastic hinges in the structure. It also examines how factors such as axial compression ratio, coupling beam cross-sectional dimensions, single-sided wall limb aspect ratio, and total floor height affect the seismic performance of this type of coupled shear wall, providing a reasonable range for axial compression ratios and coupling ratios for composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams. Based on the obtained reasonable axial compression ratio and coupling ratio, and using the analytical solution of the continuum method, a method for controlling the seismic performance of coupled shear wall structures was proposed. Results show that the composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams exhibit high load-bearing capacity and lateral stiffness under inverted triangular horizontal loads, with good displacement ductility and strong energy dissipation capability, making it an excellent seismic performance coupled shear wall system. As the axial compression ratio increases, the displacement corresponding to the yield point and peak point of the structure gradually decreases, and the displacement ductility coefficient shows a trend of first increasing and then decreasing; it is recommended that when designing steel plate-fiber reinforced concrete coupling beam-coupled shear walls, the axial compression ratio should not exceed 0.3. Numerical analysis of coupling ratio-related parameters indicates that in high-intensity seismic design areas, the range of coupling ratios should be between 45% and 60%.

Structural performance of steel reinforced concrete L-shaped columns in high temperature

This paper presented structural performance of steel reinforced concrete (SRC) L-shaped columns under high temperature and axial load coupling effects. Considering the influence of the axial load ratio (0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8), eccentricity (25, 50, 75 and 100 mm), concrete strength (40, 50, 60 and 70 MPa), calculation length (500, 1000, 1500 and 2000 mm), the SRC L-shaped columns were tested and analyzed in high temperature conditions. The results demonstrated that: (1) Concrete surface of all specimens was grayish white with many cracks. With the increasing axial load ratio, the number of cracks decreased and crack width increased. (2) The fire resistance decreased by 1.3–15.1 %, 6.1–14.9 %, and 3.8–7.1 % respectively, with increasing axial load ratio, eccentricity, calculation length; the fire resistance increased by 0.7–5.3 % with increasing concrete strength. (3) Axial displacement trend first increased gradually because of the thermal expansion of concrete, and decreased gradually after reaching the maximum axial expansion deformation. With increasing axial load ratio, the maximum axial expansion deformation decreased by 42.4–60.2 %, the time of displacement to reach the maximum expansion deformation decreased by 29.7–57.0 %, and the time of displacement to reach 0 mm decreased by 272.7–366.2 %. Finally, the calculation method for displacement and maximum bearing capacity in high temperature was proposed according to principle of virtual work, which served as a guide for fire evaluation of SRC L-shaped columns.

Reciprocity relations in a biologically inspired nanomagnonic system with dipolar coupling

Magnetosome chains in magnetotactic bacteria present ideal nanomagnonic model systems for studying collective resonance modes of dipolar-coupled single domain particles in relation to their spatial arrangement. Using microresonator-based ferromagnetic resonance (FMR) spectroscopy, electron microscopy, and micromagnetic modeling, we here provide insights into the complex magnonic activity within a single magnetosome chain. While the angular dependence of its FMR spectrum is dominated by twofold symmetry features due to the uniaxial anisotropy of linear chain segments, we also observed an unexpected behavior such as interrupted lines and flat bands due to the intricate geometrical details of this particular chain, such as a cross-like structural anomaly where a pair of particles is oriented perpendicular to the main axis of the chain and thus breaks the prevailing axial dipolar coupling symmetry. Such a cross junction formed by four particles exhibits interesting magnonic network properties. Notably, we observe reciprocity in the sense that the spectral response of one particle to an excitation of another one is identical to the response of the latter given an excitation of the former. Furthermore, we have identified that magnonic coupling between A and B can be facilitated via a dark state, as in magnonic stimulated Raman adiabatic passage, and that this dark-state coupling can be made non-reciprocal between A and B by breaking the symmetry of the spatial arrangement of the four particles.

Coverage extended MMF-based indoor OWC using overfilled launch and diversity reception

Speckle patterns generated as coherent optical beams are reflected by scattering elements. Multimode fibers (MMFs) can modify the transverse intensity distribution of speckle patterns with macro perturbations, i.e., pressures, providing a simple and low-cost way to achieve equivalent beam-steering for indoor optical wireless communications (OWCs) with divergent optical beams. However, the received optical power (ROP) variance severely limits the mobility of user terminals. In this paper, the issue is alleviated by using the overfilled launch of MMFs and the diversity gain of multi-receivers. By adjusting the axial spatial coupling distance between the MMF and the single mode fiber (SMF) emitting coherent laser, the number of excited modes of MMF can be significantly increased at 1550 nm with negligible coupling and bending losses. In addition, the signal-to-noise ratio (SNR) enhancement obtained by applying two receivers is theoretically analyzed for the case when either thermal noise or shot noise is dominant. The experimental results demonstrate that the proposed scheme can efficiently compensate for the ROP inhomogeneity, and at the same time it can extend the achievable full steering angle up to 12° at a 1.5-m free-space distance for bit error rate (BER) values of less than 3.8 × 10−3.

Analysis and prediction of vibro-acoustic characteristics of parallel propulsion systems for large-scale marine ships

The parallel power propulsion system is the preferred option for large-scale ships. The improper configuration of multidimensional power parameters is a significant factor contributing to the vibration and noise generated by the system. This study examines the sensitivity and dependence of the vibro-acoustic characteristics of the system on various power parameters through theoretical and experimental methods, and reveals the evolution mechanism of the dynamic behaviors under the coupling effect of multidimensional power parameters. Firstly, the nonlinear dynamic model considering the lateral–torsional–axial coupling of the propulsion system is established and the effects of different combinations of power parameters on the vibration response and system stability are investigated. Secondly, an experimental platform of the parallel propulsion system is constructed, and the comprehensive description of the effects of multidimensional power parameters on the vibration and noise of the system under asymmetrical input power is further provided. Finally, the radial basis function (RBF) neural network is innovatively employed to predict and approximate the vibro-acoustic characteristics of the system under the combined influence of rotating speed, torque ratio, and drag current. The research results are of significant theoretical and practical importance in breaking through the technical bottleneck related to reducing the vibration and noise of such parallel propulsion systems.

Failure mechanism and strengthening countermeasures of end-anchored cable free section under combined tension and shear

As an effective and economical reinforcement method, end anchorage cables are widely used for roadway support in coal mines. The failure of the free section of the end-anchored cable (FSEC) under the combined action of tension and shear is a key factor inducing roof collapse accidents in coal mine roadways. Based on cable bolt tensile and shear test results, this paper aims to reveal the failure mechanism of the FSEC under tension and shear by establishing a mechanical model of the interaction between the cable bolt and jointed rock mass. The results show that the axial and shear force coupling in the FSEC increases because of the joint plane shear action. The FSEC is subject to tensile–shear failure when the axial and shear forces meet the tensile–shear composite yield condition at the inflection point of the sheared cable bolt. The steel strands of the cable bolt experience and transmit shear force through the contact point, resulting in an uneven distribution of shear stress in the cable bolt cross-section, directly causing the FSEC’s local failure. Strengthening countermeasures are proposed using a high-strength slotted steel pipe to protect the cable bolt under shear, and a strengthening device has also been designed. Experimental results obtained in the laboratory have revealed that the strengthening device does not only effectively enhance the cable bolt’s shear capacity by increasing its shear strength and changing the shear transfer mode, but also significantly improves the cable bolt’s comprehensive performance. This study elucidated the failure mechanism of the FSEC and provides a practical and convenient method for increasing the shear strength of an end-anchorage cable system and enhancing roadway stability.

Nucleon axial coupling constant in a magnetar environment

Using appropriate QCD finite energy sum rules, we discuss the influence of an external magnetic field and baryonic density on the axial-vector coupling constant gA. This scenario corresponds to a magnetar environment. We found that gA decreases both as function of the magnetic field strength and the baryonic density. It turns out that at the nuclear density ρ0 the axial-vector coupling takes the value gA⁎≈0.92. Although gA decreases in general with the magnetic field intensity, gA⁎ does not change in a relevant way with the magnetic field.

Wireless Charging System with Three Arc-Transmitting Coils for Autonomous Underwater Vehicle

To enhance the misalignment tolerance of the coupling device of the autonomous underwater vehicle wireless charging system, this paper proposes a magnetic coupling device with strong misalignment tolerance. Through the Ansys Maxwell finite element analysis software, it is concluded that, under the dislocation state of the proposed magnetic coupling device, the magnetic field is mainly distributed near the shell wall of the autonomous underwater vehicle. The coupling coefficient change range under the rolling dislocation state is 0.35~0.83, the axial dislocation coupling coefficient fluctuation range is 0.79~0.83, and the radial dislocation coupling coefficient variation range is 0.48~0.83. We design and calculate the compensation network in a wireless charging system and obtain the calculation method of the compensation network. A prototype of that wireless charging system containing arc-emitting coils applied to the AUV has been made, which transfers 48 W power with an efficiency of 87.3%.

Study of the quenching of the GT-decay operator in a microscopic shell-model approach

The need of a reliable calculation of the nuclear matrix elements for the 0νββ decay has ignited a new interest about the quenching of the axial coupling constant gA , a procedure introduced to reproduce experimental results connected with GT decays. The goal of this work is to present a preliminary study to tackle this problem within the framework of the realistic shell model.

Phenomenologies in Hypersphere Soliton and Stringy Photon Models

We consider the Dirac quantization in the first-class formalism to investigate the hypersphere soliton model (HSM) defined on the S3 hypersphere. To do this, we construct the first-class Hamiltonian possessing the Weyl ordering correction. In the HSM, we evaluate the baryon physical quantities such as the baryon masses, magnetic moments, axial coupling constant and charge radii, most predicted values of which are in good agreement with the corresponding experimental data. Moreover, shuffling the baryon and transition magnetic moments, we find the model independent sum rules. In the HSM we also evaluate the baryon intrinsic frequencies such as ωN=0.87×1023s−1 and ωΔ=1.74×1023s−1 of the nucleon and delta baryon, respectively, to yield the identity ωΔ=2ωN. Next, making use of the Nambu-Goto string action and its extended rotating bosonic string theory, we formulate the stringy photon model to obtain the energy of the string configuration, which consists of the rotational and vibrational energies of the open string. Exploiting this total string energy, we evaluate the photon intrinsic frequency ωγ=9.00×1023s−1, which is comparable to the corresponding baryon intrinsic frequencies. We also predict the photon size ⟨r2⟩1/2(photon)=0.17fm, which is approximately 21% of the proton magnetic charge radius.

Evaluation of Joint Clearance Effects on the Shimmy of Nose Landing Gear

Through the establishment of a three-dimensional joint clearance model, the effects of joint clearances at different positions on shimmy stability are evaluated. In this paper, considering the radial, axial and coupling characteristics of joint clearance, the shimmy multibody dynamics (MBD) model is applied to different joints in the nose landing gear (NLG) transmission system. It is proposed to evaluate the influence of joint clearance on shimmy from two aspects of position factor and wear factor. The study found that different joint clearances have different effects on shimmy: the joint clearance between the NLG and fuselage has little influence on shimmy; the larger axial clearance of upper and lower torque link joint will cause the shimmy of the NLG, but the radial clearance has no effect on shimmy; while the joint clearance between turning sleeve and upper torque link, lower torque link and piston only works in the axial and radial coupling. The reasons for the different influence characteristics of each joint space are analyzed. Consequently, studying and summarizing the influence of different clearance on shimmy is of great significance for the design and maintenance of the NLG joints.

Functional mechanical behavior of the murine pulmonary heart valve

Genetically modified mouse models provide a versatile and efficient platform to extend our understanding of the underlying disease processes and evaluate potential treatments for congenital heart valve diseases. However, applications have been limited to the gene and molecular levels due to the small size of murine heart valves, which prohibits the use of standard mechanical evaluation and in vivo imaging methods. We have developed an integrated imaging/computational mechanics approach to evaluate, for the first time, the functional mechanical behavior of the murine pulmonary heart valve (mPV). We utilized extant mPV high resolution µCT images of 1-year-old healthy C57BL/6J mice, with mPVs loaded to 0, 10, 20 or 30 mmHg then chemically fixed to preserve their shape. Individual mPV leaflets and annular boundaries were segmented and key geometric quantities of interest defined and quantified. The resulting observed inter-valve variations were small and consistent at each TVP level. This allowed us to develop a high fidelity NURBS-based geometric model. From the resultant individual mPV geometries, we developed a mPV shape-evolving geometric model (SEGM) that accurately represented mPV shape changes as a continuous function of transvalvular pressure. The SEGM was then integrated into an isogeometric finite element based inverse model that estimated the individual leaflet and regional mPV mechanical behaviors. We demonstrated that the mPV leaflet mechanical behaviors were highly anisotropic and nonlinear, with substantial leaflet and regional variations. We also observed the presence of strong axial mechanical coupling, suggesting the important role of the underlying collagen fiber architecture in the mPV. When compared to larger mammalian species, the mPV exhibited substantially different mechanical behaviors. Thus, while qualitatively similar, the mPV exhibited important functional differences that will need to accounted for in murine heart valve studies. The results of this novel study will allow detailed murine tissue and organ level investigations of semi-lunar heart valve diseases.

Suppression of axial vibration of satellite antennas using the self-resetting frictional damper

In order to solve the problems of low-profile accuracy and poor control stability of the satellite antenna due to axial coupling vibration, in this paper, a self-resetting friction damper is proposed to suppress axial vibration. Firstly, a self-resetting friction damper, with a lightweight, wide frequency band, and high energy consumption, is designed. The principle of dry friction energy loss of metal rubber (MR) and the effect of self-resetting of shape memory alloy (SMA) are used. Secondly, the vibration reduction mechanism model of the self-resetting friction damper is established, and the principle of damping energy dissipation is analysed. Finally, sinusoidal excitation tests of the components of the satellite antennas with self-resetting friction dampers are carried out. The axial vibration loss factor of the components of the satellite antenna with the self-resetting friction damper is calculated, and the vibration resistance performance of the damper is verified. Theoretical analysis and experimental results show that the self-resetting friction damper has a significant effect on suppressing the axial vibration of the components of the satellite antenna. It is feasible to install a self-resetting friction damper in the components of the satellite antenna to suppress the axial vibration.

Revisiting proton–proton fusion in chiral effective field theory

Abstract We calculate the S-factor for proton–proton fusion using chiral effective field theory interactions and currents. By performing order-by-order calculations with a variety of chiral interactions that are regularized and calibrated in different ways, we assess the uncertainty in the S-factor from the truncation of the effective field theory expansion and from the sensitivity of the S-factor to the short-distance axial current determined from three- and four-nucleon observables. We find that S(0) = (4.100 ± 0.024(syst) ± 0.013(stat) ± 0.008(g A )) × 10−23 MeV fm2, where the three uncertainties arise, respectively, from the truncation of the effective field theory expansion, use of the two-nucleon axial current fit to few-nucleon observables and variation of the axial coupling constant within the recommended range. The increased value of S(0) compared to previous calculations is mainly driven by an increase in the recommended value for the axial coupling constant and is in agreement with a recent analysis based on pionless effective field theory.