The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.Thi...The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.展开更多
The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain si...The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho_2O_3 and Er_2O_3 were added to BaTiO_3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength E_b becomes higher.展开更多
为了研究中卫市香山地区冻雨天气成因并提高该地区冻雨天气的预报能力,本文利用常规观测资料、加密气象观测资料、MICAPS资料和香山风电场工作日志资料,对2016年3月中卫香山风电场出现的一次冰冻雨雪灾害天气过程进行天气学分析,并对冻...为了研究中卫市香山地区冻雨天气成因并提高该地区冻雨天气的预报能力,本文利用常规观测资料、加密气象观测资料、MICAPS资料和香山风电场工作日志资料,对2016年3月中卫香山风电场出现的一次冰冻雨雪灾害天气过程进行天气学分析,并对冻雨发生的物理量场、大气垂直结构和地形作用进行分析。结果表明,500 h Pa"东高西低"的环流形势是此次天气过程产生的背景条件,低层的偏南暖湿气流输送和低值系统的共同作用是产生降水的根本条件;冻雨产生时段大气温度垂直结构上、中、下层呈冷、暖、冷分布,中层有温度>0℃的暖层,近地面层为0℃或以下,中层冷平流对暖层会有破坏作用,垂直温度结构改变,降水相态随之发生变化;在同一降水过程中,山地和川区大气垂直结构存在明显差别,需关注降水相态是否一致。展开更多
自然界云由于具有动态模式多变、外表不规则等特点,故基于虚拟现实自然现象云模拟是最为复杂的模拟对象之一。该文运用环境光、漫反射光、镜面反射光处理云的光影,采用3ds MAX 2016和Open GL,实现了一天中不同时刻云的仿真以及10种具有...自然界云由于具有动态模式多变、外表不规则等特点,故基于虚拟现实自然现象云模拟是最为复杂的模拟对象之一。该文运用环境光、漫反射光、镜面反射光处理云的光影,采用3ds MAX 2016和Open GL,实现了一天中不同时刻云的仿真以及10种具有代表性云的构造与仿真。通过VC++2016编写程序,并利用AE和PR技术进行后期制作,实现了晴天云、雨天云、雪天云三种常见天气仿真,模拟效果逼真。展开更多
文摘The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.
文摘The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho_2O_3 and Er_2O_3 were added to BaTiO_3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength E_b becomes higher.
文摘为了研究中卫市香山地区冻雨天气成因并提高该地区冻雨天气的预报能力,本文利用常规观测资料、加密气象观测资料、MICAPS资料和香山风电场工作日志资料,对2016年3月中卫香山风电场出现的一次冰冻雨雪灾害天气过程进行天气学分析,并对冻雨发生的物理量场、大气垂直结构和地形作用进行分析。结果表明,500 h Pa"东高西低"的环流形势是此次天气过程产生的背景条件,低层的偏南暖湿气流输送和低值系统的共同作用是产生降水的根本条件;冻雨产生时段大气温度垂直结构上、中、下层呈冷、暖、冷分布,中层有温度>0℃的暖层,近地面层为0℃或以下,中层冷平流对暖层会有破坏作用,垂直温度结构改变,降水相态随之发生变化;在同一降水过程中,山地和川区大气垂直结构存在明显差别,需关注降水相态是否一致。
文摘自然界云由于具有动态模式多变、外表不规则等特点,故基于虚拟现实自然现象云模拟是最为复杂的模拟对象之一。该文运用环境光、漫反射光、镜面反射光处理云的光影,采用3ds MAX 2016和Open GL,实现了一天中不同时刻云的仿真以及10种具有代表性云的构造与仿真。通过VC++2016编写程序,并利用AE和PR技术进行后期制作,实现了晴天云、雨天云、雪天云三种常见天气仿真,模拟效果逼真。
