This study employed molecular dynamics simulations to explore the impact of interactions between carbon nanotube(CNT)and epoxy resin(EP)on the structural stability and friction resistance of composite materials under the influence of electric field.The findings indicate that when the electric field is applied along the X-axis(i.e.,the shear direction),increasing field strength enables CNT to more readily maintain its initial vertical orientation,while enhancing the mobility of EP molecular chains.This cooperative interaction strengthens the interfacial bonding between CNT and EP,thereby improving the mechanical performance of the material.The intense electrostatic forces generated by the electric field surpass the van der Waals forces,leading to a regular arrangement of EP molecular chains.This configuration enhances the materials resistance to reformation and shear.Compared with the improvement effect on structural stability,the friction coefficient of the material is more susceptible to the influence of the electric field strength and the direction of the applied electric field.
In this paper, we investigate an optimal investment strategy for defined-contribution (DC) pension plan under hybrid stochastic volatility (Heston–Hull–White) model, taking account of the inflation risk and the stochastic salary. The fund wealth is invested in financial market consisting of a risk-free asset, an inflation-indexed bond and a stock with hybrid Heston–Hull–White model. The goal of the pension fund manager is to maximize the expected utility of the terminal real wealth. We derive the Hamilton–Jacobi–Bellman (HJB) equation through the dynamic programming principle, under the constant relative risk aversion (CRRA) utility function, the optimal investment strategy is obtained. Finally, a numerical example is presented to characterize the impacts of financial parameters on the optimal investment strategy.
为探究氧化铋/聚丙烯腈复合纳米纤维膜的制备工艺及其X射线防护性能,以聚乙二醇为分散剂、聚丙烯腈为聚合物,将氧化铋均匀分散到聚合物溶液中,通过静电纺丝技术制备氧化铋/聚丙烯腈复合纳米纤维膜,研究氧化铋添加量对纤维膜微观形貌、力学性能及X射线防护性能的影响.结果表明:以氧化铋与聚丙烯腈的质量百分比为160%构筑的前驱体溶液,经静电纺丝并于60℃干燥2 h后可获得颗粒分散均匀、纤维形貌良好的轻质(密度为0.21 g/cm3)纳米纤维膜,其在20～120 kV管电压下的X射线衰减效率高于50%,质量衰减系数在20 kV电压下达62.16 cm2/g,具有良好的X射线防护效果,这对无铅、轻质、高屏蔽效率X射线防护材料的发展具有重要意义.
针对传统视觉SLAM算法在动态场景下难以兼顾算法定位精度与实时性的问题,提出一种基于改进Tracking线程的动态视觉SLAM算法.针对算法定位精度,以ORB-SLAM2算法为基础,在算法框架中融入Lucas-Kanade稀疏光流和Mask R-CNN图像分割网络,提高算法对潜在动态对象的感知能力.针对算法的实时性,利用Mask R-CNN图像分割网络设计异常特征点二次剔除算法,降低图像分割网络对Tracking线程耗时的影响.基于TUM与Bonn公开数据集验证算法的有效性.结果表明,改进算法的定位误差相比ORB-SLAM2、ReFusion、Dyna-SLAM算法最高降低98.62%、96.18%和91.82%,跟踪线程耗时相比 ReFusion、Dyna-SLAM 算法最高降低83.32%、88.72%,改进算法可同时兼顾算法的定位精度与实时性.
以微波辐射计在福建沿海地区的温度观测资料为研究对象,系统分析了微波辐射计大气温度廓线的反演数据,通过对微波辐射计的温度反演数据与探空和ERA5的温度进行对比,分析微波辐射计探测大气温度的能力,以及反演的数据质量,并进一步把微波辐射计的反演数据应用于分析边界层大气温度的日变化情况.结果表明:微波辐射计温度与探空温度一致性好,相关系数为0.971,平均偏差为2.716℃,均方根误差为5.131℃;降雨强度越大,降雨对微波辐射计探测大气温度准确性的影响越显著.将ERA5温度和探空获取的大气温度分别与微波辐射计获取的大气温度进行对比分析,其相关系数、平均偏差和均方根误差的逐月变化趋势一致;各月份ERA5与微波辐射计在中层大气的温度偏差小于近地面和高层大气;在高度2 km以上,ERA5与微波辐射计的温度廓线的变化趋势基本一致.在高度3 km以下,在相同的海拔高度,夏季温度日变化比冬季温度日变化小;随着海拔高度的增大,夏季大气温度变化大,冬季大气温度变化小.
