Numerical Extraction of the Equivalent Circuit for a Basic Magnetoelectric Dipole Antenna

Magnetoelectric dipoles have attracted global research attention due to its broadband, unidirectional, and high front-to-back ratio characteristics. This study implemented a co-simulation between a basic magnetoelectric dipole and its front feeding circuit through the step-by-step numerical extraction of its equivalent circuit model equipped with lumped and frequency-independent components. First, the series resonance subcircuit was derived from the series resonance point in the impedance of the magnetoelectric dipole. Second, the parallel resonance sub-circuit was achieved based on the parallel resonance point. By combining the series and parallel sub-circuits according to the sequence of their resonance frequency, the final form of the equivalent circuit for the basic magnetoelectric dipole was realized. Furthermore, to obtain the component values of the proposed circuit, a numerical fitting technique was adopted to accurately match the input impedance of the antenna and its equivalent circuit. A comparison of the circuit and antenna electromagnetic simulations showed that they agreed well with each other. Hence, the correctness and feasibility of the extraction process were verified. The overall results showed that the proposed circuit model can easily substitute for a basic magnetoelectric dipole in the implementation of antenna/circuit co-simulation in circuit simulators

Peer effects of star-analysts’ departure: new evidence from China

This paper examines how the departure of star analysts influences the performance of their non-star peers. Using manually collected data from China, we observe that non-star analysts enhance their forecast accuracy after a star analyst leaves. This effect is particularly pronounced when non-star analysts have previously worked within hierarchical teams or when the departing star analyst held significant internal resources within the brokerage. Additionally, the performance improvements are more substantial in environments with greater promotion opportunities and in brokerages characterized by a collective organizational culture. To establish causality, we leverage the suspension and subsequent reform of the star analyst voting system as an exogenous shock. A difference-in-difference analysis demonstrates that brokerages more affected by this shock exhibit larger improvements in analyst forecast accuracy. These findings offer new insights into the celebrity effect, highlighting how changes in team structure and internal competition influence analyst performance

Spatial deformation prediction method of fractured rock tunnel based on quantified GSI and its application

Abstract Determining rock mass mechanical parameters and accurately predicting tunnel deformation during tunnel construction remain challenging tasks. This study introduces a novel approach to calculate the Geological Strength Index by integrating indoor rock mechanics tests with geometric data from three-dimensional dense reconstruction. We utilized the Hoek-Brown strength criterion to develop a theoretical model for predicting tunnel deformation in fractured rock masses. Case studies reveal that the average value of Geological Strength Index for the Xiamen highway tunnel’s surrounding rock is 44. With support from the lining structure equivalent to 0.002–0.02 times the initial in-situ stress, the plastic zone thickness decreased by approximately 50%, and radial displacement was reduced by about 40%. Enhancing the lining structure’s support pressure significantly reduces the plastic zone radius and radial displacement. As the Geological Strength Index decreases, the nonlinearity between support pressure and plastic zone radius becomes more pronounced, with a similar trend observed for the relationship between support pressure and tunnel radial displacement. The relative deviation between predicted and measured values did not exceed 1.69%. The method accurately captures the effects of rock fragmentation and tunnel construction on plastic zone formation and displacement, offering an effective approach for the rapid and secure assessment of rock tunnel excavation stability using digital technology

Study on Vibration Response of Surrounding Environment Caused by High-Speed Train Operation

Abstract A finite element calculation model is established on basis of a ballastless high-speed railway passing through a section of Nanchang to study the propagation law of high-speed railway vibration in soil and the influence of hollow trench isolation on soil vibration. The three-dimensional finite element model for calculating the vibration response of high-speed railway and the two-dimensional finite element model for vibration isolation of high-speed railway are established. It is concluded that, as the train speed increases, the displacement, speed and acceleration of the soil increase, and the vibration period shortens; as the distance from the vibration source increases, the surface displacement, velocity, and acceleration of the soil f shows a trend of increasing first, then decreasing, and then increasing fluctuations along the roadbed-soil propagation path. The horizontal vibration response of the soil is greater than the vertical vibration response. And within a certain range, And in a certain range, the empty groove farther from the centerline of the track, the better the vibration isolation effect. When the train speed is 350 km/h, the distance from the vibration source should be 16 ∼ 22 m, and the vibration isolation effect is better.</jats:p