高动态GPS信号C/A码捕获方案及实现

为检测高动态GPS(Global Positioning System)信号,需要设计码环及载波环捕获与跟踪数字系统.尽量缩短盲捕时间,快速捕获到信号,是研制高动态GPS接收机技术的关键,而GPS信号C/A码的快速捕获是码跟踪和载波捕获与跟踪的基础.主要讨论了在高动态GPS信号C/A码捕获中,并行搜索法和串行搜索法的原理与实现,并结合GEC公司的十二通道相关器GP2021,给出基于DSP(数字信号处理器)技术用串行搜索法捕获高动态GPS信号C/A码的算法实现.     

科学视算──新的计算系统

一种新型的数学仿真系统一科学视算系统的特点、需要解决的问题、系统模型以及系统的构成在文中作了介绍和分析。     

Fault-tolerant control with mixed aerodynamic surfaces and RCS jets for hypersonic reentry vehicles

This paper proposes a fault-tolerant strategy for hypersonic reentry vehicles with mixed aerodynamic surfaces and reaction control systems (RCS) under external disturbances and subject to actuator faults. Aerodynamic surfaces are treated as the primary actuator in normal situations, and they are driven by a continuous quadratic programming (QP) allocator to generate torque com-manded by a nonlinear adaptive feedback control law. When aerodynamic surfaces encounter faults, they may not be able to provide sufficient torque as commanded, and RCS jets are activated to augment the aerodynamic surfaces to compensate for insufficient torque. Partial loss of effective-ness and stuck faults are considered in this paper, and observers are designed to detect and identify the faults. Based on the fault identification results, an RCS control allocator using integer linear programming (ILP) techniques is designed to determine the optimal combination of activated RCS jets. By treating the RCS control allocator as a quantization element, closed-loop stability with both continuous and quantized inputs is analyzed. Simulation results verify the effectiveness of the proposed method.     

基于我校生源调查分析下的招生宣传策略探究——以沈阳航空航天大学2013级新生为例

生源质量关乎学校的人才培养质量,是学校赖以生存与发展的命脉,招生宣传是提高生源质量的重要手段。通过对我校2013级新生生源的调查研究,利用EXCEL统计学软件对调查结果进行了详尽的统计和分析,并以此为依据探究合理、有效的招生宣传策略。     

某航天型号产品全备状态总装测试工艺方案探讨

针对某航天型号产品全备状态总装和测试提出相应的工艺方案和措施,对今后实施具有指导意义。某航天型号产品采用全备状态总装模式,在产品总装和测试过程中,火工品参与产品机械对接、综合测试。总装过程中需要将火工品装置逐一接入产品电缆网,最终使产品处于最佳安全保险状态。全备状态总装既要保证产品顺利对接,又要确保火工装置在装配、对接、测试过程中安全可靠。因此,对全备状态总装分别从安全要求及工艺流程等方面进行探索和研究,采取先进合理、安全有效的工艺措施,保证人员和产品的安全。     

封闭空间声场的有源消声技术仿真研究

基于封闭空间有源消声的基本理论,利用COMSOL软件对封闭空间声场进行了仿真建模,并模拟分析了次级声源的数量和位置关系对消声效果的影响。结果表明：次级声源布置在初级声源半波长奇数倍的空间点位时消声明显。单次级声源靠近声场中部布置时,对全声场区域消声明显;双次级声源和三次级声源布置时,使各次源保持适当距离且靠近目标区域,消声效果比较明显,区域声压级可降至60dB甚至以下。     

PTC推出优化人机交互的Pro/Engineer Mankin

数字化人体建模技术--Pro/Engimeer Mankin 近日,PTC公司推出的Pro/Engineer Mankin是一款能够使设计团队在3D产品的设计模型中插入3D数字化人体造模解决方案,用以模拟仿真及实现人机互动.     

基于SRAM型FPGA抗单粒子措施研究

文章分析了空间辐射效应对SRAM型FPGA的影响,介绍了几种可行的空间抗单粒子的措施,比较了对于不同应用情况下几种缓解措施的优劣,对于SRAM型FPGA在空间辐射环境下的使用具有参考意义。     

Design for aircraft engine multi-objective controllers with switching characteristics

The aircraft engine multi-loop control system is described and the switching control theory is introduced to solve the regulating and protecting control problems in this paper. The aircraft engine multi-loop control system is firstly described and the control problems are formulated. Secondly, the theory of the smooth switching control is devoted and a new extended scheme for the smooth switching of a switched control system is introduced. Then, for the key technologies of aero-engines switching control, a design algorithm is presented which can determine which candidate controller should be put in feedback with the plant to achieve a desired performance and the procedure to design the aircraft engine multi-loop control system is detailed. The switching performance objectives and the switching scheme are given and a family of PID controllers and compensators is designed. The simulation shows that using the switching control design method can not only improve the dynamic performance of the aircraft engine control system and reduce the switching times, but also guarantee the stability in some peculiar occasions.     

膨胀偏流喷管高度补偿机制数值研究

为了研究膨胀偏流喷管高度补偿性能,采用CFD方法,对环喉式(ATEDN)和分散式(DTEDN)膨胀偏流喷管在不同高度的工作状态进行了研究,分析了高度变化对膨胀偏流喷管性能的影响和膨胀偏流喷管的高度补偿机制。结果表明:在工作高度0km～15km内,膨胀偏流喷管推力系数优于传统喷管,具有自动补偿能力,其工作模态是从低空"开放"模态转换到高空"闭合"模态。环喉式膨胀偏流喷管性能优于分散式膨胀偏流喷管,其中心体尾锥角、收敛角和初始角存在最优角度,分别为70°,5°和65°,其中收敛角对性能影响较小。对于分散式膨胀偏流喷管,喉孔数目为6喉孔的喷管高度积分总冲比4喉孔的喷管高1.94%;采用带状喉孔的喷管高度积分总冲比圆孔喉口的喷管高3.47%。