Longitudinal Coupling Research Articles

Magnetically Induced Terahertz Birefringence and Chirality Manipulation in Transverse‐Magnetized Metasurface

AbstractActive manipulation of photonic spin state and optical chirality leads to some key applications, such as in multichannel communication, polarization‐sensitive imaging, chiral spectroscopy, and chiral sensing. Magneto‐optical materials have unique advantages in the intrinsic transmission and magnetic control of photonic chiral spin states. Here, a scheme for dynamic terahertz (THz) anisotropy and chirality manipulations in the transversely magnetized InSb and its hybrid magneto‐optical metasurface structure is presented. A special transverse photonic spin state in the InSb and a transverse−longitudinal spin coupling effect in the hybrid magneto‐optical metasurface are revealed by the eigenmode analysis and numerical simulations. The strong magnetic birefringence effect induced by this spin mode is demonstrated in the experiment. Moreover, the symmetry‐breaking mechanism in this magneto‐optical structure leads to strong intrinsic chirality and polarization conversion. The experimental results confirm the magnetically active manipulation of spin states and their asymmetric transmission in this hybrid magneto‐optical metasurface, which achieve a polarization conversion rate of near 100% and an induced intrinsic chirality of over 15 dB. This work opens a new development for active THz polarization control and chiral manipulation in the magneto‐optical microstructure.

Nonequilibrium thermal transport and photon squeezing in a quadratic qubit-resonator system

We investigate steady-state thermal transport and photon statistics in a nonequilibrium hybrid quantum system, in which a qubit shows longitudinal and quadratic coupling with an optical resonator. Our calculations are conducted with the method of the quantum dressed master equation combined with full counting statistics. The effect of negative differential thermal conductance is unravelled at finite temperature bias, which stems from the suppression of cyclic heat transitions and large mismatch of two squeezed photon modes at weak and strong qubit-resonator hybridizations, respectively. The giant thermal rectification is also exhibited at large temperature bias. It is found that the asymmetric composition of the hybrid system by spin and boson roles and negative differential thermal conductance show the cooperative contribution. Noise power and skewness, as typical current fluctuations, exhibit global maximum with strong hybridization at small and large temperature bias limits, respectively. Moreover, the effect of photon quadrature squeezing is discovered in the strong hybridization and low-temperature regime, which shows asymmetric response to two bath temperatures. These results would provide some insight to thermal functional design and photon manipulation in qubit-resonator hybrid quantum systems.

Longitudinal coupling of momentary stress reactivity and trait neuroticism: Specificity of states, traits, and age period.

Personality traits like neuroticism show both continuity and change across adolescence and adulthood, with most pronounced changes occurring in young adulthood. It has been assumed, but insufficiently examined, that trait changes occur gradually over the years through the accumulation of daily experiences. The current longitudinal measurement burst study examined (a) how changes in average momentary stress reactivity are coupled with changes in trait neuroticism, (b) the extent to which this coupling is specific to stress reactivity and neuroticism, and (c) the extent to which there are age differences in the association between changes in stress reactivity and changes in neuroticism. Participants (N = 581; 50% male) between 14 and 86 years of age completed up to 3 waves (T1-T3) of Big Five trait questionnaires and experience-sampling assessments during 6 years. During each three-week experience-sampling period, participants reported their momentary affect and occurrences of hassles on average 55 times. Latent change models showed that increases over time in affective reactivity to daily hassles were associated with increases in neuroticism. This effect was consistent from T1 to T2 as well as from T2 to T3, and most pronounced in young adulthood. Importantly, the results were specific to associations between stress reactivity and neuroticism because changes in frequency of hassles in daily life did not predict changes in neuroticism, and stress reactivity did not consistently predict changes in the other Big Five traits. The findings help to inform theoretical models that outline how short-term states might contribute to gradual longer-term changes in traits like neuroticism. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Active tuning of longitudinal strong coupling between anisotropic borophene plasmons and Bloch surface waves.

Strong coupling between the resonant modes can give rise to many resonant states, enabling the manipulation of light-matter interactions with more flexibility. Here, we theoretically propose a coupled resonant system where an anisotropic borophene localized plasmonic (BLP) and Bloch surface wave (BSW) can be simultaneously excited. This allows us to manipulate the spectral response of the strong BLP-BSW coupling with exceptional flexibility in the near infrared region. Specifically, the strong longitudinal BLP-BSW coupling occurs when the system is driven into the strong coupling regime, which produces two hybrid modes with a large Rabi splitting up to 124 meV for borophene along both x- and y-directions. A coupled oscillator model is employed to quantitatively describe the observed BSW-BLP coupling by calculating the dispersion of the hybrid modes, which shows excellent agreement with the simulation results. Furthermore, benefited from the angle-dependent BSW mode, the BSW-BLP coupling can be flexibly tuned by actively adjusting the incident angle. Such active tunable BLP-SBW coupling with extreme flexibility offered by this simple layered system makes it promising for the development of diverse borophene-based active photonic and optoelectronic devices in the near infrared region.

Combined Effect of Beam-Beam Interaction and Beam Coupling Impedance in Future Circular Colliders

The future large scale electron-positron colliders, such as FCC-ee in Europe and CEPC in China, will rely on the crab waist collision scheme with a large Piwinski angle. Differently from the past generation colliders both luminosity and beam-beam tune shifts depend on the bunch length in such a collision scheme. In addition, for the future circular colliders with extreme beam parameters in collision several new effects become important such as beamstrahlung, coherent X-Z instability and 3D flip-flop. For all these effects the longitudinal beam dynamics plays an essential role and should be taken into account for the collider luminosity optimization. In this paper we discuss an impact of the longitudinal beam coupling impedance on the collider performance.

Extraction of carrier concentration and mobility of ZnO by mid-infrared reflectance spectroscopy

As a representative of the third-generation semiconductors, ZnO has great development potential in the fields of optics and electricity, so the measurement on its electrical properties is quite important. Here, we try to extract the carrier concentration and mobility of ZnO by mid-infrared reflectance spectroscopy. Considering that the longitudinal optical phonon-plasmon coupling (LOPC) mode formed by the coupling of ZnO optical phonons and free carriers depends on carrier concentration and mobility, we conduct a test on the MIR spectra (400-1600 cm−1) of ZnO crystals with different carrier concentration (1018-1015 cm−3). By fitting the strong reflection peak shape corresponding to phonon-polaritons formed by the coupling of its LOPC and infrared light through m-CDF model, the carrier concentration and mobility of these samples are obtained, which are consistent with those got from the Hall-effect measurement.

A novel Z-shaped elastic flange structure for increasing the amplitude output of a piezoelectric ultrasonic transducer

A novel Z-shaped elastic flange structure is presented in this paper, which is used to mount the piezoelectric ultrasonic transducer (PUTs) together with the housing and increase amplitude output of the transducer. Generally, the mounting fixture of the transducer refers to the traditional flat-faced flange structure, which has the advantages of low processing cost and easy installation. However, considering its structural characteristics, the flange structure also exerts a negative influence on the coupling between the transducer and housing and accordingly suppresses the conversion of ultrasonic vibration energy inside the transducer. The novel Z-shaped elastic flange is combined with a traditional flat-faced flange structure and an elastic cylindrical sleeve, and the amplitude output of the transducer is increased by reducing the longitudinal and radial coupling effect between the transducer and the flange. Ultrasonic transducers with different flange structures are designed and manufactured. Through the combination of Finite Element Method and experimental analysis, the decoupling and amplitude increase ability of the novel elastic flange are investigated in detail. The results show that without changing the stiffness of the transducer, the proposed Z-shaped elastic flange structure could significantly increase the amplitude output of the transducer, regardless of whether the transducer was working in a resonance state. Hence, the newly proposed structure serves as a meaningful attempt and can be used as a universal structure for PUTs in different fields.

Optimized piezoelectric properties and temperature stability in PSN‐PMN‐PT by adjusting the phase structure and grain size

AbstractFor relaxor ferroelectric materials, improving the piezoelectric properties and temperature stability simultaneously is still a great challenge up to now. In this work, the structure, electric properties, and thermal stability of xPSN‐(1 − x)PMN‐0.4PT (x = 0.15, 0.29, 0.43, and 0.5) ceramics were studied systematically by experiment and phase field simulation. A high Curie temperature Tc of 255℃ and good longitudinal electricmechanical coupling factor k33 of 0.75 and piezoelectric constant d33 of 650 pC/N are achieved in x = 0.43 ceramics with monoclinic C and tetragonal phases coexistence at room temperature. At 30℃, this composition ceramics sintered at 1260℃ shows the remnant polarization Pr and coercive field Ec are about 36.8 µC/cm2 and 8.2 kV/cm respectively. Moreover, as the temperature increases to 150℃, these values remain as high as 22.6 µC/cm2 and 5.7 kV/cm. In the temperature range of 30–230℃, the variation of k33 and d33 is about 24% and 25%. These high piezoelectric performance and superior temperature stability are related to the more complex domain structures caused by phase coexistence and larger grains with more stable domain structure due to internal stress. The former is beneficial in improving the piezoelectric properties, and the latter dominates the enhanced temperature stability.

Coupling impedance of a PEC angular strip in a vacuum pipe

This study deals with the evaluation of the longitudinal and transverse coupling impedance of a charge travelling in a drift tube with a perfectly electric conductive angular strip. The problem is formulated in the particle frame as dual series equations, and efficiently solved through the representation of the unknown in terms of Neumann series. Then, the electric parameters are obtained in the pipe frame through the Lorentz transforms. The presented solution can be adopted as the general methodology in case of angular discontinuities in particle accelerators.

Nonlinear flow-induced vibration response characteristics of leaching tubing in salt cavern underground gas storage

To address flow-induced vibration failure problems of leaching tubing in salt cavern underground gas storage, a nonlinear flow-induced vibration model of the leaching tubing in salt cavern gas storage was established using the energy method, element method, and Hamilton variational principle. In the model, nonlinear factors such as the longitudinal and lateral coupling effect and contact/collision between the center tube and middle tube (tube in tube) were considered. Based on the on-site M example well parameters in Jianghan Oilfield, an experiment to simulate leaching tubing vibration was designed using the similarity principle and carried out to verify the validity and correctness of the proposed model. Thus, the effects of the water injection flow rate, two-port distance, and tubing diameter on the vibration response characteristics of the leaching tubing were analyzed systematically. The vibration failure mechanism of the leaching tubing was revealed, and vibration control methods of the leaching tubing were proposed. First, with the increase in water injection flow rate, the lateral displacement and bending stress of the lower end of the leaching tubing increase, and when the injection flow rate was 50–70 m3/h, the vibration intensity of string increased significantly; therefore, the on-site water injection flow rate should be avoided using this interval operation. Second, with the increase in the two-port distance, the vibration response of the center tube increased; when the two-port distance was greater than 40 m, the vibration amplitude and energy of the tubing string increased significantly, and thus the two-port distance should be less than 40 m to the greatest extent possible in on-site production. Third, when the diameter of the leaching tubing decreased, the vibration amplitude and frequency increased, and the corresponding probability of bending deformation and fatigue failure increased significantly; therefore, provided that the other conditions are met, selecting a large tubing string can effectively improve the safety of the leaching tubing string.

Longitudinal coupling impedance of a particle traveling in PEC rings: A regularised analysis

Longitudinal coupling impedance of a particle traveling in PEC rings: A regularised analysis

The magnetic properties and hysteresis loops of mixed spin-(3/2,2) hexagonal Ising nanowire system with alternate layers

In this paper, we have examined in detail the behavior of magnetic properties, hysteresis loops, and compensation phenomenon of a ferrimagnetic mixed spin-(3∕2,2) hexagonal Ising nanowire with alternate layers within the Monte Carlo method based on the Metropolis algorithm. The effect of longitudinal crystal field and exchange coupling constants on the total and the sublattice magnetizations, susceptibilities, specific heat, internal energy, as well as hysteresis loops are investigated for particular parameters. The obtained résults showed different interesting magnetic phenomena, such as seven and triple hysteresis loops at low temperatures, and one or double compensation temperatures under certain parameter values. Our outcomes are also compared with various experimental and theoretical studies.

Magnetic field induced ferroelectric polarization voltage in compositional dependent (0–3) NFO/P(VDF-TrFE) nanocomposite film

A novel two-phase multiferroic 0–3 nanocomposite (NC) films of NiFe2O4/P(VDF-TrFE) (thickness ∼ 40 µm) were fabricated for 0.2, 0.5, 1, 1.5 and 2 volume percentage of NiFe2O4 (NFO) particles in P(VDF-TrFE) matrix. Such flexible, thick, semi-crystalline NC films exhibit dielectric permittivity ∼6.7 at room temperature with low dielectric loss tangent (tanδ). These NC films exhibit ferroelectricity up to 1% volume content of NFO at room temperature and the ferroelectricity decreases for higher volume percentage of NFO due to increase in conductivity and deterioration of ferroelectric polymer chain. This is also confirmed from J–E and SEM analysis. The NC films display magnetic behavior at room temperature due to incorporation of NFO nanoparticles. The transverse magnetoelectric coupling coefficient (α V 31) value is found to be higher compared to longitudinal coupling coefficient (α V 33) for composite films. The maximum α V 31 value is found to be 136.4 mVOe−1cm−1 at 1.21 kOe DC magnetic field for 0.5% NFO/P(VDF-TrFE) poled composite film with application of 25 Oe alternating magnetic field. It is the highest ever reported value in case of (0–3) NFO/P(VDF-TrFE) composite. Hence, the NC films having less than 1% volume content of NFO would perform a wide range of potential applications as well as electrically controlled magnetic storage and sensor devices, etc.

Longitudinal and lateral collision avoidance control strategy for intelligent vehicles

In order to solve the problems of longitudinal and lateral control coupling, low accuracy and poor real-time of existing control strategy in the process of active collision avoidance, a longitudinal and lateral collision avoidance control strategy of intelligent vehicle based on model predictive control is proposed in this paper. Firstly, the vehicle nonlinear coupling dynamics model is established. Secondly, considering the accuracy and real-time requirements of intelligent vehicle motion control in pedestrian crossing scene, and combining the advantages of centralized control and decentralized control, an integrated unidirectional decoupling compensation motion control strategy is proposed. The proposed strategy uses two pairs of unidirectional decoupling compensation controllers to realize the mutual integration and decoupling in both longitudinal and lateral directions. Compared with centralized control, it simplifies the design of controller, retains the advantages of centralized control, and improves the real-time performance of control. Compared with the decentralized control, it considers the influence of longitudinal and lateral control, retains the advantages of decentralized control, and improves the control accuracy. Finally, the proposed control strategy is simulated and analyzed in six working conditions, and compared with the existing control strategy. The results show that the proposed control strategy is obviously better than the existing control strategy in terms of control accuracy and real-time performance, and can effectively improve vehicle safety and stability.

Fabrication and measurement of fiber optic localized surface plasmon resonance sensor based on gold nanoparticle dimer

Fiber optic localized surface plasmon resonance (FO LSPR) sensors capable of portable, real-time, and remote sensing are emerging with the progress of lab-on-fiber technology. However, the small area of the substrate by the optical fiber often restricts the sensitivity of the FO LSPR sensors. To improve the performance of the FO LSPR sensors, it is necessary to enhance the interactions between incident light and plasmonic nanostructures within a defined region. Dimer in which two nanoparticles are arranged with nanometer spacing can effectively increase the light-nanostructure interactions. It is well known that the nanogap made in the assembled nanoparticles significantly enhances the intensity of the electromagnetic field in the confined area by the hot spot effect. We fabricate the dimers of gold nanoparticles on the optical fiber with benzenethiol using a method that reduces the repulsive force between the nanoparticles. In the dimers, the strong plasmonic interaction between the two nanoparticles produces a longitudinal plasmon coupling band, which is compared to the transverse plasmon band by the monomer-based FO LSPR sensor with a similar density of gold nanoparticles. In the proposed sensor, the longitudinal band displays approximately 9.1 times improved sensitivity. When two types of sensors are applied to the biosensor application, the dimer-based FO LSPR sensor also proves an improved limit of detection of about 2.6 times. This method is expected to become a milestone in the field of measurement for small molecules and low concentration through the advancement of the yield and density of dimers.

Integrating Multimodal and Longitudinal Neuroimaging Data with Multi-Source Network Representation Learning.

Uncovering the complex network of the brain is of great interest to the field of neuroimaging. Mining from these rich datasets, scientists try to unveil the fundamental biological mechanisms in the human brain. However, neuroimaging data collected for constructing brain networks is generally costly, and thus extracting useful information from a limited sample size of brain networks is demanding. Currently, there are two common trends in neuroimaging data collection that could be exploited to gain more information: 1) multimodal data, and 2) longitudinal data. It has been shown that these two types of data provide complementary information. Nonetheless, it is challenging to learn brain network representations that can simultaneously capture network properties from multimodal as well as longitudinal datasets. Here we propose a general fusion framework for multi-source learning of brain networks - multimodal brain network fusion with longitudinal coupling (MMLC). In our framework, three layers of information are considered, including cross-sectional similarity, multimodal coupling, and longitudinal consistency. Specifically, we jointly factorize multimodal networks and construct a rotation-based constraint to couple network variance across time. We also adopt the consensus factorization as the group consistent pattern. Using two publicly available brain imaging datasets, we demonstrate that MMLC may better predict psychometric scores than some other state-of-the-art brain network representation learning algorithms. Additionally, the discovered significant brain regions are synergistic with previous literature. Our new approach may boost statistical power and sheds new light on neuroimaging network biomarkers for future psychometric prediction research by integrating longitudinal and multimodal neuroimaging data.

Longitudinal Coupling of Depression in Parent-Adolescent Dyads: Within- and Between-Dyad Effects Over Time.

The present work evaluated reciprocal, within-dyad associations between parent-adolescent depressive symptoms across two independent samples (N=327 and N=435 dyads, respectively; approximately 85% biological mothers) assessed every three months for two (Study 1) to three (Study 2) years. Results of random intercept cross-lagged panel models converged to support positive contemporaneous patterns of co-fluctuation in parent and adolescent depression, such that within-person deviations in parental depression were associated with same direction within-person deviations in adolescent depression at the same timepoint. In contrast, within-person fluctuations in parent depression did not predict prospective within-person fluctuations in adolescent depression, or vice versa, across the follow-up period. Results held across boys and girls, as well as dyads with and without a parental history of depressive disorder. Overall, findings advance knowledge by demonstrating that, after accounting for between-person/dyad variance, parent and adolescent depression demonstrate contemporaneous co-fluctuations, but do not demonstrate within-dyad reciprocity over time.

Damage mechanism modelling of shield tunnel with longitudinal differential deformation based on elastoplastic damage model

Shield tunnels with great longitudinal differential deformations will adversely affect the service performance and optional safety of the metro system. Previous studies on the longitudinal mechanical behavior of shield tunnel are mostly carried out within the framework of elastic or elastic–plastic theory. However, assuming the concrete as elastoplastic body cannot properly reflect its nonlinear mechanical characteristics such as strain softening, stiffness degradation, etc., while damage or crack inevitably occurs when shield tunnel suffers large deformations. Therefore, the nonlinear damage characteristics of concrete material are considered in this paper, a novel positive/negative decomposition of stress tensor in energy norm is introduced herein to consider the asymmetric tensile/compressive material behavior of concrete, and a bi–scalar damage constitutive model of concrete is developed in turn. Then, to investigate the damage and degradation mechanisms of shield tunnel with differential deformation, the 3D discontinuous contact model is employed to develop the elaborate tunnel–soil numerical model. Results show that when shield tunnel suffers differential deformation, tensile damage dominates while compressive damage is minor, additional shear force and bending moment are induced, the ovality of tunnel cross section and serviceability also vary along the longitudinal direction. The damage and degradation of concrete material will reduce the tunnel integral stiffness and attenuate its ability to resist longitudinal and circumferential deformation. Besides, the segmental rebar is hard to yield, while the longitudinal coupling bolts on the lower half of tunnel segments with large deformation are inclined to yield. It should be noted that, the segmental rings near the inflection point of longitudinal deformation profile are most severely damaged, and exhibit the largest convergence deformation and lowest serviceability, where special attentions should be paid.

A coupled force predictive control of vehicle stability using front/rear torque allocation with experimental verification

This paper investigates the handling control and stability of an all-wheel-drive vehicle whose axles are individually equipped with an electric motor connected to an open differential. This could offer a potential configuration for the mass production of electric all-wheel-drive vehicles because of reduced cost and complexity. Although there is no torque vectoring or direct yaw moment control in this configuration, considerable handling improvement can be achieved by optimised front/rear torque distribution due to the longitudinal and lateral tire force coupling. In this study, a model predictive control design is presented with a coupled force prediction model for vehicle handling dynamics. The controller optimises the front/rear torque allocation to track the desired handling response and ensure vehicle stability. This study also compensates for actuator delay by incorporating the actuator dynamics into the control design. The performance of the proposed controller is evaluated through software simulations and experimental tests conducted on an electric all-wheel-drive Chevrolet Equinox.

Impedance optimization and measurements of the injection stripline kicker

Stripline kickers are commonly used for on-axis injection in the low emittance rings. The beam coupling impedances of the kickers normally show large contributions to the total impedance budget. In the High Energy Photon Source, the necessity of the short pulse bottom width (less than 10 ns) and strong deflection field requires the kicker to have a short length and a small gap between the electrodes, respectively. A new five-cell stripline kicker is proposed in order to save longitudinal space as well as to reduce the beam coupling impedance. Comprehensive studies have been undertaken to characterize the impedance of the stripline kicker. The beam coupling impedance and heat load dissipation on the kicker due to the beam passage are studied numerically. Strategies to further reduce the impedance are discussed. In addition, impedance bench measurements are launched to identify the impedance of the kicker experimentally. The longitudinal beam coupling impedance is measured with different terminations by using coaxial wire method. A satisfactory agreement has been reached between the numerical predictions and the measurements. A novel fasten block design with ceramic is proposed for the wire stretching and the center holding of the inner conductor in a small beam pipe.