A new Monte Carlo simulation of the track structure of low-energy electrons （〈10keV） in liquid water is presented. The feature of the simulation is taken into consideration of the condensed-phase effect of liquid w...A new Monte Carlo simulation of the track structure of low-energy electrons （〈10keV） in liquid water is presented. The feature of the simulation is taken into consideration of the condensed-phase effect of liquid water on electron elastic scattering with the use of the Champion model, while the dielectric response formalism incorporating the optical-data model developed by Emfietzoglou et al. is applied for calculating the electron inelastic scattering. The spatial distributions of energy deposition and inelastic scattering events of low-energy electrons with different primary energies in liquid water are calculated and compared with other theoretical evaluations. The present work shows that the condensed-phase effect of liquid water on electron elastic scattering may be of the influence on the fraction of absorbed energy and distribution of inelastic scattering events at lower primary energies, which also indicate potential effects on the DNA damage induced by low-energy electrons.展开更多
Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a ...Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in Abaqus.It is then compared to the performance of a ballasted track.First,slab and ballasted track models are developed to replicate the full-scale testing of track sections.Once the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track results.The slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the models.Trains travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical speeds.Various train loading methods are discussed,and the most practical approach is retained and described.Moreover,correlations are made between the geotechnical parameters of modern high-speed rail and conventional standards.It is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds.展开更多
针对最大功率点跟踪(Maximum power point tracking, MPPT)算法中传统滑模控制存在收敛速度慢、抖振显著等不足,提出一种基于RBF神经网络的光伏系统非线性反步积分滑模(Nonlinear backstepping integral sliding mode control, NBISMC)...针对最大功率点跟踪(Maximum power point tracking, MPPT)算法中传统滑模控制存在收敛速度慢、抖振显著等不足,提出一种基于RBF神经网络的光伏系统非线性反步积分滑模(Nonlinear backstepping integral sliding mode control, NBISMC)最大功率点跟踪策略。首先,采用RBF神经网络对各种气象条件下的光伏电池输出电压进行预测;其次,设计非线性积分滑模面以改善传统滑模控制存在稳态误差及超调量大的问题;最后,设计新型指数趋近律,在加快收敛速度的同时有效削弱了系统高频抖振;通过Lyapunov函数分析非线性反步积分滑模控制的可达性与稳定性,并在静态、动态和遮光条件下进行仿真试验。仿真试验结果表明,在温度和光照强度发生变化的工况下,相比于传统滑模控制,基于RBF神经网络的非线性反步积分滑模控制能在各种气象条件下快速、准确地跟踪光伏系统最大功率点,具有较强的鲁棒性。展开更多
文摘A new Monte Carlo simulation of the track structure of low-energy electrons （〈10keV） in liquid water is presented. The feature of the simulation is taken into consideration of the condensed-phase effect of liquid water on electron elastic scattering with the use of the Champion model, while the dielectric response formalism incorporating the optical-data model developed by Emfietzoglou et al. is applied for calculating the electron inelastic scattering. The spatial distributions of energy deposition and inelastic scattering events of low-energy electrons with different primary energies in liquid water are calculated and compared with other theoretical evaluations. The present work shows that the condensed-phase effect of liquid water on electron elastic scattering may be of the influence on the fraction of absorbed energy and distribution of inelastic scattering events at lower primary energies, which also indicate potential effects on the DNA damage induced by low-energy electrons.
基金Engineering and Physical Sciences Research Council (EPSRC) is also acknowledged for funding this work under Grant Number EP/N009207/1.
文摘Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in Abaqus.It is then compared to the performance of a ballasted track.First,slab and ballasted track models are developed to replicate the full-scale testing of track sections.Once the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track results.The slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the models.Trains travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical speeds.Various train loading methods are discussed,and the most practical approach is retained and described.Moreover,correlations are made between the geotechnical parameters of modern high-speed rail and conventional standards.It is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds.
文摘针对最大功率点跟踪(Maximum power point tracking, MPPT)算法中传统滑模控制存在收敛速度慢、抖振显著等不足,提出一种基于RBF神经网络的光伏系统非线性反步积分滑模(Nonlinear backstepping integral sliding mode control, NBISMC)最大功率点跟踪策略。首先,采用RBF神经网络对各种气象条件下的光伏电池输出电压进行预测;其次,设计非线性积分滑模面以改善传统滑模控制存在稳态误差及超调量大的问题;最后,设计新型指数趋近律,在加快收敛速度的同时有效削弱了系统高频抖振;通过Lyapunov函数分析非线性反步积分滑模控制的可达性与稳定性,并在静态、动态和遮光条件下进行仿真试验。仿真试验结果表明,在温度和光照强度发生变化的工况下,相比于传统滑模控制,基于RBF神经网络的非线性反步积分滑模控制能在各种气象条件下快速、准确地跟踪光伏系统最大功率点,具有较强的鲁棒性。
