快速加热恒应力试验方法的初步研究

短时高温试验是适应现代高速飞行器的发展而建立起来的一种新型的力学性能试验方法。目前已有多种试验方案, 其中快速加热恒应力拉伸试验是在某恒定应力下, 以一定的速率加热试件, 测定合金的应变与温度的关系, 并从而求得材料在试验条件下的屈服温度(通常以引起0.2%的残余应变为准)。本文简要地评述了短时高温试验方法的现状; 介绍了为进行快速加热恒应力拉伸试验而建立的试验装置, 并提供了国产Д16AT及B95AT合金的初步试验数据;最后还对所得数据进行处理和分析。     

宽弦空心风扇转子叶片鸟撞损伤数值仿真

为解决航空发动机宽弦空心风扇转子叶片抗鸟撞设计问题,对宽弦空心风扇转子叶片鸟撞损伤进行了数值仿真。采用光滑质点流体动力学（SPH）算法建立鸟体模型,采用J-C本构模型和失效模型定义材料冲击下动态性能,建立旋转状态下叶片鸟撞数值仿真方法,经过试验验证能够较准确预测叶片损伤。开展相同条件下鸟撞击宽弦空心和实心风扇转子叶片仿真,对比鸟撞击叶片过程、撞击时叶片叶尖最大轴向和径向变形、撞击后叶片永久变形,研究被鸟撞击后空心叶片相比实心叶片的损伤特征。结果表明：空心和实心叶片鸟撞击过程相同;空心叶片被鸟撞击后叶尖轴向和径向变形更小;空心叶片被鸟撞击后前缘卷边变形更严重,对风扇气动性能和稳定性影响更大;在结构设计时应适当增加前缘空心区域局部刚度,或者适当增大前缘实心区域范围,用于提高空心叶片的抗鸟撞能力。     

微絮凝变孔隙深层过滤处理低浊度废水研究

本文研究了微絮凝变孔隙深层过滤处理低浊度废水时,滤料粒径、絮凝剂种类、投加量、滤速等因素对过滤效果的影响。试验结果表明：在达到相同出水水质的情况下,由于变孔隙结构等原因,该系统具有用药量省、阻力损失小、出水量大及整床过滤效能好等优点。     

DDS在跳频频率合成器中的应用

本文对直接数字频率合成（DDS）基本原理进行了简要介绍,提出了一种由DDS和直接频率合成（DS）构成的适用于宽带跳频通信系统的频率合成器设计方案。     

控制力矩陀螺框架谐波减速驱动系统建模与仿真

摘要： 控制力矩陀螺是航天器姿态控制系统的重要执行机构,它具有输出力矩大、速度响应快、功率消耗低、寿命长等优点,可以完成高速率的姿态机动控制.综合考虑谐波减速器的齿隙模型、非线性刚度、减速器效率等因素,对CMG框架驱动组件用谐波减速器进行精细建模.针对低速下谐波减速器的刚度较低、传动误差较大这一缺陷,建立考虑传动误差的减速器模型;与传统的不考虑传动误差的模型相比可更准确地描述谐波减速器在低速下的输出速度曲线.根据建立的CMG框架驱动系统模型,在低速下采用PID闭环控制对输出转速误差进行抑制,使输出转速误差降低了50%以上.最后分析其对谐波减速器刚度和阻尼对框架系统性能的影响.     

Influence of lunar topography on simulated surface temperature

The surface temperature of the Moon is one of the essential parameters for the lunar exploration, especially to evaluate the Moon thermophysical features. The distribution of the temperature is heavily influenced by the Moon topography, which, however, is rarely studied in the state-of-art surface temperature models. Therefore, this paper takes the Moon topography into account to improve the surface temperature model, Racca model. The main parameters, such as slopes along the longitude and latitude directions, are estimated with the topography data from Chang’E-1 satellite and the Horn algorithm. Then the effective solar illumination model is then constructed with the slopes and the relative position to the subsolar point. Finally, the temperature distribution over the Moon surface is obtained with the effective illumination model and the improved Racca model. The results indicate that the distribution of the temperature is very sensitive to the fluctuation of the Moon surface. The change of the surface temperature is up to 150 K in some places compared to the result without considering the topography. In addition, the variation of the surface temperature increases with the distance from the subsolar point and the elevation, along both latitude and longitude directions. Furthermore, the simulated surface temperature coincides well with the brightness temperature in 37 GHz observed by the microwave sounder onboard Chang’E-2 satellite. The corresponded emissivity map not only eliminates the influence of the topography, but also hints the inherent properties of the lunar regolith just below the surface. Last but not the least, the distribution of the permanently shadowed regions (PSRs) in the lunar pole area is also evaluated with the simulated surface temperature result.     

Intra-annual variations of the thermospheric density at 400 km altitude from 1996 to 2006

We investigate the intra-annual variations of globally averaged thermospheric density at 400 km altitude from 1996 to 2006 by using Artificial Neural Network Method (ANNM). The results indicate that thermospheric density is governed by solar activity, and the absolute error of our model is 13.67%, less than NRLMSISE-00 model. Fourier representation can catch the intra-annual variations more accurately than NRLMSISE-00 model and JB2008 model especially during 2002. We find that the Autumn maximum is slightly greater than Spring maximum during solar minimum, while the reverse is correct during solar maximum. There is a strong linear relation between solar activity and the amplitude of annual/semiannual variations, and the correlation coefficients are 0.9534 and 0.9424, respectively. Moreover, the amplitude ratio of the annual to semiannual variation is about 1.3 averaged, and changes in different years, but it has little relation with solar activity. Besides that, the amplitude of annual variation is larger than semiannual variation during 1996 and 2006 except 1998 and 2000. The relative error of NRLMSISE-00 model is 14.95%, decreasing to 12.49% after revising, and the correlation coefficients between this empirical model and its improved results and the observation are 0.8185 and 0.9210, respectively. Finally, we suggest the revised version of MSIS series of model should use the Fourier representation to express the intra-annual variations.     

B747-400型飞机气象雷达显示故障的分析与排除

B747—400货机是南方航空公司的主力货运机型,机载气象雷达系统是用来探测和显示飞机前方航路上危险气象目标的设备,由于该机型搭载的气象雷达型号较新,出现故障后可供查阅的资料较少,通过对该系统显示故障的排故过程分析,阐述对该系统维护的一些经验和建议。     

武术套路锻炼对大学生心理健康影响的研究

采用文献资料、实验、症状自评量表(SCL-90)、数理统计等方法,通过对随机选择的100名18-20岁自愿参加武术套路锻炼的大学生人群进行12个月武术套路锻炼的实验,分析和探讨武术套路锻炼对大学生心理健康的影响。结果显示:大学生武术套路锻炼人群12个月实验后的心理状态明显好于实验前;其中3项指标具有显著性差异(P<0.05),5项指标差异性非常显著(P<0.01)。研究表明:武术套路锻炼能够较全面地改善大学生的心理状态,提高心理健康水平,可以作为大学生提高身心健康水平的一种手段;但武术套路锻炼是内外兼修较为长期的过程,部分心理因子在短期内效果甚微。