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"simulation tests"
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Deformation and Stability in Coal Seam Mining Under Fluid–Solid Coupling
Reasonable retention of safe coal and rock pillars is significant for safe mining and liberating coal resources under thick loose aquifers. The 18,041 working face of Chengcun Mine is taken as the research background. The elastic foundation model of the rock-clay synergistic aquiclude was creatively constructed, and the structural instability criterion was derived. The dynamic evolution law of thin bedrock failure and the vertical settlement law of clay layer are studied by numerical simulation test. A similar material simulation test is used to simulate the development law of water flowing fractured zone and the evolution law of vertical displacement of rock strata under the condition of fluid–solid coupling and to verify the stability of rock-clay synergistic water-resisting structure. The research shows that: (1) The maximum tensile stress in the middle of the long side of the rock stratum at the top of the bedrock is 0.652 MPa, less than its tensile strength threshold. (2) The clay and rock layers at the top of the bedrock have a synergistic settlement. The vertical settlement distribution transitions from a 'concentric circle' to a 'concentric ellipse'. The maximum deformation value in the central area is 0.5 m. (3) The development of water-conducting fractures under the thick loose layer and thin bedrock presents a 'double peak and one valley' shape, with a maximum height of 45.2 m. The rock-clay synergistic water-resisting structure maintains the effective water-resisting property, thus verifying the feasibility of the 4 m mining scheme.
Journal Article
Nonlinear Acceleration of Ultrarelativistic Electrons in the Outer Radiation Belt Disrupted by Transverse Wave Modulations
Whistler‐mode waves scatter ultrarelativistic electrons in the radiation belts and accelerate them through resonant interactions. In simplified models, nonlinear phase trapping by high‐amplitude waves can increase electron energy by several MeV within seconds. However, the acceleration rate in realistic wave packets is slower due to small‐scale wave field structures reducing trapping efficiency. While previous studies focused on short field‐aligned amplitude modulations and phase jumps, we examine the effects of transverse modulations, which have been observed to reach scales comparable to ultrarelativistic electron gyroradii. Using test‐particle simulations, we demonstrate that these modulations disrupt the acceleration process. Our numerical results suggest that nonlinear trapping plays a negligible role in accelerating electrons above a certain energy limit, reinforcing the diffusive nature of wave‐driven electron transport at multi‐MeV energies. Unlike field‐aligned structures, transverse phase incoherence modifies the effective wave spectrum and allows for resonance, making amplitude modulations a necessary component for suppression of acceleration.
Journal Article
On the Particle Motion in Paleo‐Magnetosphere During the Geomagnetic Polarity Reversal
During the Earth's magnetic reversal, the dipole component of the magnetic field weakens, and the non‐dipole component becomes dominant, resulting in a far more complex magnetospheric topology than that of a dipole. In this study, we used a particle tracing technique to investigate the motion of ions within an irregular magnetosphere during the Matuyama‐Brunhes magnetic polarity reversal. Compared to the scenario in which the geomagnetic field is dominated by a dipole component, earthward‐moving particles can be hardly “trapped” in the inner magnetosphere when the geomagnetic field experiences the polarity reversal, and particles can directly precipitate into the Earth's atmosphere on a global scale. It suggests that under an irregular magnetospheric configuration, the traditional trapped region of particles (e.g., radiation belt or ring current) no longer exists. Plain Language Summary During the Earth's paleomagnetic reversal, the strength of the Earth's magnetic field was approximately 10% of its current value, accompanied by a weakening of the dipole component and an enhancement of the non‐dipole component. Under the superposition of this non‐axisymmetric multipole magnetic field, the magnetospheric structures may undergo significant changes. How charged particles travel in such an irregular magnetosphere and how different their trajectories are compared to the well‐known textbook scenario are still unknown. In this study, by utilizing global MHD simulations and test‐particle tracing techniques, we trace the charged particle's trajectory within the magnetosphere during the Matuyama‐Brunhes magnetic polarity reversal. We found that under an irregular magnetosphere in the middle stage of the geomagnetic reversal, particles in the inner magnetosphere cannot be constantly trapped around the Earth. The traditional trapped region (e.g., radiation belt or ring current) no longer exists. Particles moving Earthward do not gain the same acceleration effect as those under the present‐day magnetic field topology, resulting in a globally distributed pattern of particle precipitation. These differences can affect the global energy deposition and particle distribution in near‐Earth space. Key Points We simulated charged particles' trajectories in the magnetosphere during the Matuyama‐Brunhes reversal Particles cannot be “trapped” in an irregular magnetosphere The irregular geomagnetic field results in global particle precipitation
Journal Article
Relativistic electron microbursts associated with whistler chorus rising tone elements: GEMSIS-RBW simulations
Relativistic electron microbursts, which are bursty enhancements of the precipitation of relativistic electrons, are often observed by low‐altitude satellite measurements. These microbursts are likely to play an important role in high‐energy electron flux loss in the outer radiation belt. Some observations suggest that whistler chorus waves are a cause of relativistic electron microbursts. First, we derived the relativistic time of flight model considering the propagation of whistler mode waves, and then investigated characteristics of the precipitations. We found that relativistic electron precipitation has a positive energy dispersion at low altitude. The duration of electron precipitation by one whistler chorus element decreases when the energy of the precipitated electrons is increased. We then performed three‐dimensional test particle simulation with a newly developed wave‐particle interaction model using realistic plasma parameters in the inner magnetosphere. The test particle simulation showed for the first time that the resonant interactions with whistler chorus elements at high‐latitudes produce bursty enhancements of relativistic electron precipitation, thus confirming the results of the TOF analysis. A few Hz modulations are embedded in the precipitating electron flux variations, which is associated with the repetition period of the whistler chorus elements. The simulation results indicate that microbursts of relativistic electrons of the outer belt are caused by chorus wave‐particle interactions at high latitudes and a series of rising tone elements of chorus waves produce a few Hz modulation of microbursts observed by the SAMPEX satellite. Key Points Newly developed GEMSIS‐RBW code that can solve wave‐particle interactions Energy dispersion of relativistic electron precipitations derived from TOF model A few Hz modulation of microbursts associated with whistler chorus emissions
Journal Article
Selected Simulation and Experimental Studies of the Heat Transfer Process in the Railway Disc Brake in High-Speed Trains
The effectiveness of railway brakes strongly depends on their thermal condition. A computer simulation and experimental investigations on a full-scale dynamometric stand were chosen as an adequate analysis of the heat transfer process in brakes. The article introduces a two-dimensional, axisymmetric numerical model of the tested disc brake. Boundary conditions related to the heat generated in the friction brake and heat transferred to the environment are also presented. The transient heat transfer problem was solved using the in-house computer program of the finite element method. The article presents simulations and experimental investigations of the intensive braking of a train with an initial high speed. Temperature responses of the disc brake on the friction surface and at other selected points are shown. In addition, a thermal imaging camera was used to assess the temperature distribution on the friction surface of the disc. The results of experimental and simulation tests were preliminarily compared. Similar maximum temperature values were obtained at the end of braking with a particular discrepancy in temperature responses during the analyzed process.
Journal Article
Artificial intelligence test: a case study of intelligent vehicles
To meet the urgent requirement of reliable artificial intelligence applications, we discuss the tight link between artificial intelligence and intelligence test in this paper. We highlight the role of tasks in intelligence test for all kinds of artificial intelligence. We explain the necessity and difficulty of describing tasks for intelligence test, checking all the tasks that may encounter in intelligence test, designing simulation-based test, and setting appropriate test performance evaluation indices. As an example, we present how to design reliable intelligence test for intelligent vehicles. Finally, we discuss the future research directions of intelligence test.
Journal Article
Research on the Application of Adaptive Genetic Algorithm in Software Unit Security Test Simulation
At present, the security test and simulation of software unit mainly focuses on several links, such as software control structure amelioration, software process alternating quantity model control and model inspection tech, and there are still many shortcomings, such as high missed inspection rate, difficult to effectively guarantee the needs of practice, etc. Based on this, this paper first analyses the purpose and principle of software unit security test and simulation, then studies the utilization of ameliorated genetic algorithm in software unit security test simulation, and finally gives the simulation results analysis of software unit security test based on AGA.
Journal Article
Cascade Sliding Mode Control for Linear Displacement Positioning of a Quadrotor
This paper contains an example of a simulation implementation of sliding mode control algorithms for the problem of adjusting the linear position of a quadrotor. A mathematical model of the drone was proposed, which was then implemented in a simulation environment. The method of designing sliding mode controllers using the Lyapunov method in order to improve stability was presented. A cascade system based entirely on sliding mode control algorithms is introduced. The article ends with a comparative analysis of simulation test results of classical control systems and controllers based on sliding mode control.
Journal Article