一种多串口和以太网转换方法的研究

嵌入式系统中普遍应用RS232串口进行调试通信，但RS232串口在复杂的综合化航电处理平台中的应用却有诸多不便，而通过以太网却无相关问题。鉴于当前大多数成熟应用都需要通过RS232进行通信，设计了一种新型接口模块，实现了将多个RS232串口协议数据转换为以太网协议数据的方法。实践表明，方法能很好地应用在复杂的综合化航电处理环境中，简单方便，不影响用户调试习惯，值得推广应用。     

多核处理器P2020的访存实时性分析与优化

多核处理器以其高集成度、高性能功耗比的特点，获得了军事、电信、网络等领域的关注，但多个处理核心对共享资源的抢占带来的实时性问题阻碍了多核处理器在上述领域的应用。面向实时性的代表指标———访存时间，以P2020为研究对象，分析了其实时性的影响因素，采用可变步长的模型，对各种影响因素进行了定量的测试与分析，为多核处理器访存实时性的优化提供了参考。     

Simulation study on slant-to-vertical deviation in two dimensional TEC mapping over the ionosphere equatorial anomaly

With the rapid increase of GPS/GNSS receivers being deployed and operated in China, real-time GPS data from nearly a thousand sites are available at the National Center for Space Weather, China Meteorology Administration. However, it is challenging to generate a high-quality regional total electron content (TEC) map with the traditional two-dimensional (2-D) retrieval scheme because a large horizontal gradient has been reported over east–south Asia due to the northern equatorial ionization anomaly. We developed an Ionosphere Data Assimilation Analysis System (IDAAS), which is described in this study, using an International Reference Ionosphere (IRI) model as the background and applying a Kalman filter for updated observations. The IDAAS can reconstruct a three-dimensional ionosphere with the GPS slant TEC. The inverse slant TEC correlates well with observations both for GPS sites involved in the reconstruction and sites that are not involved. Based on the IDAAS, simulations were performed to investigate the deviation relative to the slant-to-vertical conversion (STV). The results indicate that the relative deviation induced by slant-to-vertical conversion may be significant in certain instances, and the deviation varies from 0% to 40% when the elevation decreases from 90° to 15°, while the relative IDAAS deviation is much smaller and varies from −5% to 15% without an elevation dependence. Compared with ‘true TEC’ map derived from the model, there is large difference in STV TEC map but no obvious discrepancy in IDAAS map. Generally, the IDAAS TEC map is much closer to the “true TEC” than is STV TEC map is.     

Boundary condition modelling and identification for cantilever-like structures using natural frequencies

The actual boundary conditions of cantilever-like structures might be non-ideally clamped in engineering practice, and they can also vary with time due to damage or aging. Precise modelling of boundary conditions, in which both the boundary stiffness and the boundary mass should be modelled correctly, might be one of the most significant aspects in dynamic analysis and testing for such structures. However, only the boundary stiffness was considered in the most existing methods. In this paper, a boundary condition modelling and identification method for cantilever-like structures is proposed to precisely model both the boundary stiffness and the boundary mass using sensitivity analysis of natural frequencies. The boundary conditions of a cantilever-like structure can be parameterized by constant mass, constant rotational inertia,constant translational stiffness, and constant rotational stiffness. The relationship between natural frequencies and boundary parameters is deduced according to the vibration equation for the lateral vibration of a non-uniform beam. Then, an iterative identification formulation is established using the sensitivity analysis of natural frequencies with respect to the boundary parameters. The regularization technique is also used to solve the potential ill-posed problem in the identification procedure.Numerical simulations and experiments are performed to validate the feasibility and accuracy of the proposed method. Results show that the proposed method can be utilized to precisely model the boundary parameters of a cantilever-like structure.     

The Magnetospheric Multiscale Magnetometers

The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University’s Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored on board so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.     

基于仿真分析的压铆力预测模型

铆接是飞机结构机械连接的主要方式,压铆力作为影响铆接质量的重要因素,传统的计算方法通常是建立在体积不变的假设之上,且不考虑钉杆材料被压入钉孔部分的体积,导致模型误差较大。为此,依据仿真分析结果和铆钉材料的流动趋势,引入体积缩减系数来描述钉杆被压入钉孔部分的体积,建立压铆力预测模型,并与已有的试验数据进行对比,结果表明计算值与试验值的一致性较好,该模型可以用来预测铆接过程中压铆力的大小。     

一种PowerPC和FPGA结构的远程接口单元设计方法

远程接口单元（ RIU）已经是综合化模块化航空电子系统的重要组成部分。分析了分布式IMA架构下航空电子系统对远程接口的新需求,提出了一种基于PowerPC ＋FPGA结构的远程接口单元设计方法。通过设计方法不仅实现了单元综合多种I／O资源,还保证了单元具有一定的容错和可配置特性,并在远程接口关键技术方面取得了实质性的突破。     

国外搓(滚)丝工艺控制技术

要想搓（滚）出合格的螺纹标准件，首先要选择合适的毛坯直径。毛坯直径选得过大或过小都无法加工出合格的螺纹产品。全国螺纹标委会与３０１所前不久曾就此问题组织了专题学术研讨，对美国、日本、前苏联的毛坯直径计算方法作了概要介绍，这里就不再赘述了。除与毛坯直径...     

轮胎参数对双轮式起落架刹车耦合振动影响研究

目前对飞机起落架低频刹车耦合振动问题的研究主要停留在考虑轮胎参数影响的起落架纵向单自由度振动特性分析，对于多自由度低频刹车耦合振动的特性研究不足。基于Simcenter 3D 动力学分析软件建立双轮支柱式起落架刚柔耦合整机滑跑刹车分析模型，研究轮胎竖向刚度和侧偏刚度对双轮支柱式起落架低频刹车纵向、横向和扭转的多自由度耦合振动的影响。结果表明：轮胎的竖向刚度对起落架横向和扭转方向上的振动影响较大，轮胎竖向刚度变化33%，横向和扭转方向上的振动变化5% 左右；轮胎的侧偏刚度对起落架低频刹车横向上的振动影响较大，轮胎侧偏刚度变化33%，横向上的振动变化15% 左右。     

企业微机管理信息系统

本文介绍了《企业微机管理信息系统》的开发与实现。