太阳质量损失对行星轨道的影响

本文利用Ｇｙｌｄｅｎ－Ｍｅｓｈｃｈｅｒｓｋｉｉ方程和Ｅｄｄｉｎｇｔｏｎ－Ｊｅａｎｓ定律，讨论太阳质量损失对行星轨道的影响，结果表明由于太阳质量损失会产生轨道半长径α的一阶周期项和二阶混合项；近日点角距ω的一阶周期项、二阶长期项和混合项，行星轨道半长径的长期变化会影响太阳系的稳定性。     

推力矢量和二元喷管

推力矢量是第四代战斗机获得过失速机动性的必要条件,而二元喷管又是推力矢量控制中性能较为优越的一类喷管。本文较全面地阐述了目前世界上推力矢量和二元喷管的发展和现况、二元喷管的构造和性能、二元喷管对改进飞机升阻特性和机动的作用。推力矢量能显著提高飞机在空战中的作战效率以及推力矢量控制所需的效能也在文中作了介绍。     

太阳射电微波爆发的频谱分析

1981年4月1日太阳发生一个4N级Hα耀斑并伴随出现强烈的IV型射电爆发.本文对北京天文台,西澳大利亚站等射电资料进行分析.分析表明:(1)该事件的微波源状态相对稳定,米波源位置存在移动,因此产生微波辐射与米波辐射是两组不同的电子群体,在爆发频谱指数的时变曲线上表现出明显的形态差异.还由于两者辐射源的位置不同,微波与米波的爆发在峰值时刻上也不完全符合.(2)4月1日微波大爆发是由三个主爆发组成的,它们的峰值时刻分别为0135.1,0146.1,0153.6UT.由射电高频端谱指数算出的非热电子能谱指数表明,在射电爆发的三个峰值时刻电子能谱都变硬.本文还得出该活动区的非热电子平均速度(以光速c为单位)β为0.9左右,磁场强度B为430G.并由回旋同步辐射阻尼算得,非热电子的寿命为829秒,这个数值与三个主峰的持续时间相吻合.     

喷流噪声特性与控制研究

本文着重研究喷流噪声机理及工程计算方法。通过实验研究了声功率与喷流速度的关系,表明在Mα>0.4时Lighthill方程和Lilley方程均与实验数据吻合,可分别使用。而Mα<0.4时,均偏差较大,通过本文实验表明,若改为6次方关系较为恰当。文章同时对喷流噪声指向性、谱特性进行了分析。最后对一种引射消声器进行了发展性研究,获得在135dB噪声条件下,降噪17dB的效果。     

同无黑子耀斑相协的微波爆发机制的探讨

1980—1984年期间,我们在云南天文台9375MHz,3653MHz和2902 HHz三个波段的射电观测资料中,查到11组微波爆发与无黑子耀斑相伴随。本文研究了这些爆发与耀斑的大气层高度,射电爆发类型以及通过落进峰值流量-时间图的位置,确认出爆发机制是活动区中作麦克斯韦分布电子的热轫致辐射。     

Exploration and implementation of commonality valuation method in commercial aircraft family design

Commercial aircraft family design can reduce development costs, shorten development cycles, and expand the market coverage of aircraft. Commercial aircraft family development has become one of the most important features of modern aircraft design. This paper explores the effects of commonality on different aircraft models in a commercial aircraft family. The existing product commonality indexes are summarized and their limitations in the application to aircraft design are discussed. Then a new component commonality index is proposed based on the component decomposition structure. A model for calculating the aircraft program value is established,which considers development costs, manufacturing costs, sale price, operation costs and residual costs. The effects of aircraft commonality on time and economic costs of both development and manufacturing, and on sale price, are analyzed and quantified. The commonality evaluation strategy is obtained, which features comprehensive consideration of the aircraft program value and time costs. The break-even analysis of aircraft is proceeded on the basis of costs and price data. By using a real option method, the strategy considers the uncertainty of the aircraft program and the flexibility of the manufacturer. This strategy proves to be rational and applicable to aircraft design based on the calculation of three examples and the analysis of parameter sensitivity.     

再论和谐社会的构建——基于功能冲突论视阈

作为对二战后美国社会矛盾激化、社会动荡的回应,在对社会学家关于社会冲突的种种观点反思与发展的基础上,科塞建立了功能冲突论。科塞的功能冲突论由冲突正功能的发挥条件、冲突正功能的具体内容、社会安全阀制度等内容组成。功能冲突论启示我们,在我国构建和谐社会的过程中,要正视、分析社会矛盾、社会冲突,构建社会安全阀制度,消除社会冲突产生的社会土壤。     

Application of small-size antennas for estimation of angles of arrival of HF signals scattered by ionospheric irregularities

A modification of the Doppler Interferometry Technique is suggested to enable estimating angles of arrival of comparatively broadband HF signals scattered by random irregularities of the ionospheric plasma with the use of small-size weakly directional antennas. The technique is based on the measurements of cross-spectra phases of the probe radiation recorded at least in three spatially separated points. The developed algorithm has been used to investigate the angular and frequency-time characteristics of HF signals propagating at frequencies above the maximum usable one (MUF) for the direct radio path Moscow-Kharkiv. The received signal spectra show presence of three families of spatial components attributed, respectively, to scattering by plasma irregularities near the middle point of the radio path, ground backscatter signals and scattering of the sounding signals by the intense plasma turbulence associated with auroral activations. It has been shown that the regions responsible for the formation of the third family components are located well inside the auroral oval. The drift velocity and direction of the auroral ionosphere plasma have been determined. The obtained estimates are consistent with the classical conception of the ionospheric plasma convection at high latitudes and do not contradict the results of investigations of the auroral ionosphere dynamics using the SuperDARN network.     

High temporal resolution global PWV dataset of 2005–2016 by using a neural network approach to determine the mean temperature of the atmosphere

Atmospheric water vapour plays an important role in phenomena related to the global hydrologic cycle and climate change. However, the rapid temporal–spatial variation in global tropospheric water vapour has not been well investigated due to a lack of long-term, high-temporal-resolution precipitable water vapour (PWV). Accordingly, this study generates an hourly PWV dataset for 272 ground-based International Global Navigation Satellite System (GNSS) Service (IGS) stations over the period of 2005–2016 using the zenith troposphere delay (ZTD) derived from global-scale GNSS observation. The root mean square (RMS) of the hourly ZTD obtained from the IGS tropospheric product is approximately 4 mm. A fifth-generation reanalysis dataset of the European Centre for Medium-range Weather Forecasting (ECMWF ERA5) is used to obtain hourly surface temperature (T) and pressure (P), which are first validated with GNSS synoptic station data and radiosonde data, respectively. Then, T and P are used to calculate the water vapour-weighted atmospheric mean temperature (Tm) and zenith hydrostatic delay (ZHD), respectively. T and P at the GNSS stations are obtained via an interpolation in the horizontal and vertical directions using the grid-based ERA5 reanalysis dataset. Here, Tm is calculated using a neural network model, whereas ZHD is obtained using an empirical Saastamoinen model. The RMS values of T and P at the collocated 693 radiosonde stations are 1.6 K and 3.1 hPa, respectively. Therefore, the theoretical error of PWV caused by the errors in ZTD, T and P is on the order of approximately 2.1 mm. A practical comparison experiment is performed using 97 collocated radiosonde stations and 23 GNSS stations equipped with meteorological sensors. The RMS and bias of the hourly PWV dataset are 2.87/?0.16 and 2.45/0.55 mm, respectively, when compared with radiosonde and GNSS stations equipped with meteorological sensors. Additionally, preliminary analysis of the hourly PWV dataset during the EI Niño event of 2014–2016 further indicates the capability of monitoring the daily changes in atmospheric water vapour. This finding is interesting and significant for further climate research.