支承舱减振性能分析

支承舱是运载火箭与航天器之间的重要连接结构,支承舱的振动特性是力学环境设计需要考虑的因素之一.本文从振动环境控制的角度进行支承舱结构动力学分析,阐述了一种基于支承舱振动特性研究的改善航天器力学环境的方法.在有限元建模过程中,引入了材料级性能试验.计算并比较了不同材料支承舱结构对航天器振动环境的作用,比较了连接面形式对振动环境的影响.基于分析结果给出了进一步研究的建议.     

基于TestStand的自动测试系统软件设计

为满足测试系统多功能测试状态的需求,开发了一种基于TestStand的自动测试系统软件;该软件使用TestStand引擎对复杂的自动测试流程和测试资源进行管理;实际应用表明,该软件能够简化测试流程,有效提高了测试系统的测试效率,减少了软件维护成本,同时,该系统软件具有良好的兼容性和灵活性。     

自由空间MIMO信道测量系统

介绍了MIMO系统无线信道研究的现状,对现阶段的MIMO信道建模方法进行了分析和比较,提出了自由真实空间内的MIMO信道实时测量系统方案,该系统采用USRP平台,能实时地测量真实空间通信信道传输性能,并对信道数据进行存储分析,该系统成本低,为真实MIMO信道研究提供了基础.     

An iterative approach for sparse direction-of-arrival estimation in co-prime arrays with off-grid targets

This paper addresses the problem of direction of arrival (DOA) estimation by exploiting the sparsity enforced recovery technique for co-prime arrays, which can increase the degrees of freedom. To apply the sparsity based technique, the discretization of the potential DOA range is required and every target must fall on the predefined grid. Off-grid target can highly deteriorate the recovery performance. To the end, this paper takes the off-grid DOAs into account and reformulates the sparse recovery problem with unknown grid offset vector. By introducing a convex function majorizing the given objective function, an iterative approach is developed to gradually amend the offset vector to achieve final DOA estimation. Numerical simulations are provided to verify the effectiveness of the proposed method in terms of detection ability, resolution ability and root mean squared estimation error, as compared to the other state-of-the-art methods.     

Imaging and Doppler parameter estimation for maneuvering target using axis mapping based coherently integrated cubic phase function

In this paper, we propose a novel imaging and Doppler parameter estimation algorithm for ground maneuvering targets. Since the cross-track acceleration will induce the quadratic chirp rate (third-order phase) in the phase history, it may cause the maneuvering target severely smeared in the Doppler domain. To obtain a well-focused target imaging result, the quadratic chirp rate must be estimated accurately. Though cubic phase function (CPF) is efficient in estimating the parameters of a single maneuvering target, it may suffer from the identifiability problem when dealing with multiple maneuvering targets. To address these issues, an axis mapping (AM) based coherently integrated cubic phase function (CICPF) algorithm is proposed. This algorithm consists of two stages. Firstly, the linear chirp rate migration (i.e. quadratic chirp rate) of target in the time and chirp-rate domain is corrected by AM. After that, a dechirping technique is utilized to coherently integrate the auto-terms, and suppress the cross-terms and spurious peaks. Compared with several existing quadratic chirp rate estimation approaches, AM based CICPF (AMCICPF) algorithm can acquire lower signal-to-noise ratio threshold and estimate the centroid frequency, chirp rate and quadratic chirp rate of maneuvering target simultaneously. By compensating the chirp rate and quadratic chirp rate, a finely focused maneuvering target imaging can be obtained. Both simulated and real data processing results show that the AMCICPF algorithm serves as a good candidate for maneuvering target Doppler parameter estimation and imaging.     

基于LabVIEW的增压控制器测试设备软件设计

LabVIEW作为一种功能强大的虚拟仪器开发环境得到广泛的应用。利用LabVIEW设计测试设备软件,读取存储在EXCEL表格中的贮箱压力值,通过RS485串口通信发送给增压控制器作为模拟压力值,增压控制器通过接收的压力值来控制电磁阀的启闭以此验证增压控制的功能,实现软件的测试功能。利用LabVIEW可以设计出简洁友好的界面,方便操作和观察。有效降低程序的计算量,能够做到实时读取和发送。     

飞轮通用测试软件平台的设计与实现

针对原有飞轮测试设备复用性差、维护成本高、难以保证多套产品同步自动测试的问题,设计开发了针对多型号飞轮的通用自动化测试系统;通过深入分析,提炼出多个产品在测试过程中功能的一致性和接口的差异性,采用分层架构、抽象工厂的设计模式以及配置文件的方法,解决了测试软件的通用性问题;提出了基于测试流程表的自动测试解决方案,能够适应多种测试流程的要求,扩展性强;采用混合多线程并行处理架构,解决了资源冲突,完善了多台飞轮的并行测试;该测试软件已在多型号飞轮的批产任务中使用,稳定可靠、适应性强,提高了设备使用率三倍以上,大大提升了飞轮批产测试效率。     

基于USB的卫星通用化地面测试软件的设计

针对当前卫星地面测试设备研制任务剧增、研制需求周期短、密度大、技术更新快的问题,将软件工程中的组件技术引入卫星测试软件领域,提出利用测试功能组件构建通用化测试软件的设计思路;首先,对现有卫星型号的地面测试任务做共性研究;然后,分析研究现有卫星数传分系统和测控分系统单机地面测试涵盖的所有测试功能,描述通用化测试软件的研制需求;以通用化和模块化的设计思路进行软件概要设计;通过分析软件组成、设计流程图、搭建软件界面等步骤进行软件详细设计;最后,软件实现;提出的基于USB接口的卫星通用化地面测试软件,通过某型号功放级地面测试和某型号Ka应答机地面测试,经验证,通用性强,覆盖功能全面,能较好地满足多个分系统单机设备的测试要求。     

PROFINET的实时性及其协议分析

针对目前现场总线技术无法满足工业控制领域对信息传输的速率以及信息传输实时性的较高需求,PROFINET实时协议迅速发展起来,该协议在通信方面较现场总线技术有更好的实时性以及更高的传输速率;首先对标准TCP/IP协议进行了研究,分析了PROFINET对标准TCP/IP协议的优化方式;然后详细介绍了PROFINET RT和PROFINET IRT的帧结构以及基于具体数据的实时性分析,为西门子STEP7对PROFINET的组态配置提供了一定的借鉴作用;最后采用西门子的PROFINET IO设备、IO控制器等,通过STEP7的组态配置,验证了PROFINET IO之间的通信。     

ReaxFF molecular dynamics simulations of n-eicosane reaction mechanisms during pyrolysis and combustion

The pyrolysis and combustion mechanism of the hydrocarbon fuel has important scientific and practical significance. However, it is difficult to detect the whole intermediates and products using traditional methods, which brings trouble to the analysis of the reaction process. In this paper, the microscopic reaction mechanism and the main products of n-eicosane (C₂₀H₄₂) were simulated based on the reactive force field molecular dynamics (ReaxFF-MD). The effects of temperature (2000–3500 K) and oxygen on the initial decomposition, the distribution of main products, and the reactive pathways of C₂₀H₄₂ fuel were studied to determine its reaction mechanism. The initial decomposition of C₂₀H₄₂ was mainly initiated by small alkyl radicals in pyrolysis, and by the oxygen-containing radicals in combustion. The participation of oxygen had a greater effect on accelerating the decomposition reaction. The reactions involving oxygen of C₂₀H₄₂ initial decomposition accounted for 87.5% of the total reactions at 2000 K. Moreover, the detailed distribution and formation pathways of the main products of H₂, C₂H₄, CH₄, H₂O, CO, and CO₂ were depicted to construct the overall reaction mechanism of C₂₀H₄₂. •H radical formed from the composition of C₂H₄ was exactly consistent with the •H radical consumed by the generation of CH₄ and H₂ in the pyrolysis stage. The feasibility of the simulation method was verified by the result of thermal analysis. The results are helpful for further research on the reaction mechanism of hydrocarbon fuels.