国航货运计算机系统的网络设计

介绍了国航货运计算机系统的网络拓朴结构、网络需求和网络设计思想.如何使SITA网络和本地局域网连接,解决SNA/LAN的互联方案.     

Measurements of the 12C/13C Ratio in Planetary Nebulae and Implications for Stellar Evolution

We present the results of a study aimed at determining the 12C/13C ratio in two samples of planetary nebulae (PNe) by means of mm-wave observations of 12CO and 13CO. The first group includes six PNe which have been observed in the 3He+ hyperfine transition; the other group consists of 23 nebulae with rich molecular envelopes. We have determined the isotopic ratio in 14 objects and the results indicate a range of values between 9 and 23. In particular, three PNe have ratios well below the value predicted by standard evolutionary models ( 20), indicating that some extra-mixing process has occurred in these stars. We briefly discuss the implications of our results for standard and nonstandard stellar nucleosynthesis.     

Impact Cratering Theory and Modeling for the Deep Impact Mission: From Mission Planning to Data Analysis

The cratering event produced by the Deep Impact mission is a unique experimental opportunity, beyond the capability of Earth-based laboratories with regard to the impacting energy, target material, space environment, and extremely low-gravity field. Consequently, impact cratering theory and modeling play an important role in this mission, from initial inception to final data analysis. Experimentally derived impact cratering scaling laws provide us with our best estimates for the crater diameter, depth, and formation time: critical in the mission planning stage for producing the flight plan and instrument specifications. Cratering theory has strongly influenced the impactor design, producing a probe that should produce the largest possible crater on the surface of Tempel 1 under a wide range of scenarios. Numerical hydrocode modeling allows us to estimate the volume and thermodynamic characteristics of the material vaporized in the early stages of the impact. Hydrocode modeling will also aid us in understanding the observed crater excavation process, especially in the area of impacts into porous materials. Finally, experimentally derived ejecta scaling laws and modeling provide us with a means to predict and analyze the observed behavior of the material launched from the comet during crater excavation, and may provide us with a unique means of estimating the magnitude of the comet’s gravity field and by extension the mass and density of comet Tempel 1.     

Large scale structure of the universe

The current situation with the cosmological model and fundamental constants is briefly reviewed. Here, we concentrate on evolutionary effects of large-scale structure formation, in particular, the relationship with the quasar distribution and dynamics is discussed. We argue that groups of bright quasars with few or more than dozen of members within regions l _LS(100–150)h ^–1 Mpc found atz<2 may belong to concentrations of young rich clusters of galaxies, and thus be distant Great Attractors like the local GA or the Shapley concentration. These early large-scale galactic structures (i) provide a natural way to bias the distribution of Abell clusters, and (ii) suggest that the spectrum of primordial density perturbations is nearly flat on scales encompassing both the cluster and GAs,l=k ^–1(10,100)h ^–1 Mpc: _k ² k ³ P(k) k , =1 _–0.4 ^+0.6 , whereP(k) is the power spectrum of density perturbations.     

基于MATLAB的自动控制系统仿真与分析

本文在给出机器人行走系统的数学模型的基础上，利用 MATLAB对控制系统进行仿真，同时详细地分析了控制系统，给出了系统的时域性能指标、开环频率特性及根轨迹，说明了系统设计的有效性。     

射频制导导弹全自动综合测试系统

介绍用于射频制导导弹全自动综合测试系统的设计方法，论述系统测试功能及实现的关键技术，通过举例阐述系统应用软件设计。该系统从方案入手，提出并解决了几个关键技术，从而保证整个系统研制的质量，同时应用了若干项新技术，体现了系统设计的先进性。系统成功实现了对导弹全自动综测。试验表明，该系统集成方法先进，自动化程度高，性能稳定可靠，为系统实现导弹故障诊断目标打下了坚实的基础。     

精密车削细长轴的几点措施

本文针对长径比大于80：1的细长轴精密加工问题，从车刀角度、车削方法、车床尾座、跟刀架等方面提出了改进措施，从而满足了加工要求，提高了生产效率。     

Pulsar radio emission

25 years after their discovery, pulsars still pose fundamental problems, in particular when the whole range of their periodsP is considered: 1.56 ms P0.09 s. This communication reviews my understanding of the pulsar magnetosphere, windzone, and (coherent) radio emission. New are details of the preferred magnetic structure, wind generation, and amplification of the emitted (pseudo) curvature radiation, the inferred brightness of which exceeds that of all other terrestrial and astrophysical sources by many orders of magnitude.     

飞机机翼表面水滴撞击特性计算

根据飞机防冰系统的研制需要，以机翼为对象，对水滴撞击特性的数值计算进行研究，建立了计算模型，研究了计算方法，用相应的计算程序，在广泛的飞行，气象及多种翼型条件下，对水滴撞击特性作了计算，计算结果与国外权威机构公布的数据相比吻合性好，给出了部分计算结果，并对水滴撞击特性计算的应用作了简要分析。     

线性回归模型的贝叶斯决策方法

决策影响图分析法是决策问题一种新的图示表征求解方法，它用无有向回路的有向图来表征决策信息的关系，运用这一决策分析的新方法，对一类线性回归模型，从决策的角度进行探讨和求解，并将结果推广到更加一般的情形。