Ka频段飞行器测控与通信系统设计

传统基于S频段的统一载波测控通信系统受工作频率低、占用频带窄的特点限制,无法满足现代及未来飞行器测控与通信系统对于高速数传、通信带宽、安装空间、克服“黑障”及抗干扰性等方面日益增长的需求,提出一种Ka频段直接序列扩频体制的飞行器测控与通信系统以解决上述问题;利用Ka频段频带宽、空间选择性好、减小“黑障”影响等特点,同时采用直接序列扩频通信体制实现遥测、外测和遥控等不同功能点频统一和信道统一,简化系统结构、减小设备体积;介绍了系统架构及主要设备组成,阐述了基带数据综合设备、Ka频段一体化终端设备等单机的详细设计及天线的选择,并给出了地面测试系统方案;该系统具备体积小、频带宽、扩展性好等特点,可满足未来飞行器测控与通信系统的设计与应用需求。     

基于伏安法的润滑剂可靠性评估技术

介绍了润滑剂可靠性的评估指标,并从原理上分析了如何进行润滑油的伏安法可靠性评定。应用该种技术可以快速、方便地对润滑剂中抗氧剂、总酸值/总碱值等可靠性指标进行定量分析,并可以通过抗氧剂的消耗趋势进行剩余使用寿命(RUL)、粘度和酸值的相互关系分析,可以预测设备的反常情况;根据实验所得数据,可以有效地掌握抗氧剂的消耗时间和速率,增加设备的可靠性,减少维修费用。     

基于拜占庭故障模式的空天飞行器GNC系统架构研究

针对空天飞行器对GNC系统的高可靠性需求,开展了基于拜占庭故障模式的GNC系统架构研究,采用四机三总线架构设计方案,通过系统内总线实现输入数据及输出数据多机冗余比对,防止拜占庭故障的发生,提升了系统可靠性,实现了系统自检测和故障的准确定位及隔离,并具有在线故障诊断、故障自修复功能,同时解决了高动态、强干扰环境下系统自主性较差的问题,提升了GNC系统可靠性和容错性;经分析,该系统架构能够满足空天飞行器在轨、再入复杂任务需求。     

Time-optimal flatness based control of a gantry crane

This contribution deals with the flatness based control of a gantry crane, where the control objective is to transfer the load from an initial rest position to a final rest position in a minimal transition time. It is well-known that the type of crane model we consider is a differentially flat system, and that the position of the load is a flat output. We exploit this property both for the design of a tracking control as well as for planning time-optimal reference trajectories for the load. We discuss the design of the tracking control in detail, and show in particular how a standard approach which can be found in the literature can be modified systematically such that instead of measurements of certain time derivatives of the flat output we can use measurements of the state of the system. We also present a new approach for the design of time-optimal reference trajectories. In order to solve the resulting nonlinear optimization problem numerically, we use a primal-dual interior point method. Finally, we conclude with measurement results that stem from an implementation on a laboratory model.     

SIS冗余结构可靠性影响参数分析

可靠性是衡量安全仪表系统性能（SIS）优劣的重要指标之一。本文基于故障树模型的SIS可靠性公式,对安全仪表系统常用5种冗余结构5个参数进行Matlab程序仿真,直观的分析各参数对SIS常用冗余结构可靠性的影响,分析冗余结构可靠性性能关系,分析结果对安全仪表系统的设计和整改具有重要意义。     

Boosting transduction coefficient in BaTiO3-Based piezoceramic through phase boundary engineering

Transduction coefficient (d₃₃×g₃₃) is the core parameter for evaluating piezoelectric energy harvesting materials. However, due to the thermodynamic constraints, the synergistic variation between piezoelectric charge constant (d₃₃) and dielectric constant (ε_r) indeed hinder the further increase of d₃₃×g₃₃. Herein, an enhanced d₃₃×g₃₃ of 13,000 × 10^?15 m²/N was achieved in 0.80BaTiO₃-0.10CaTiO₃-0.10BaZrO₃ (BC_0.1ZT) lead-free solid solution for the first time through a phase boundary engineering strategy. The high d₃₃×g₃₃ mainly stems from non-synergistic variation of dielectric and piezoelectric performance in the rhombohedral-orthorhombic (R-O) phase boundary, in which the low ε_r comes from the increased domain size and reduced domain wall density; while the high configurational sensitivity of the unique domains to external electric field contributed to the high d₃₃. Our findings provide an alternative approach for enhanced energy harvesting performance by tracing the strategy of designing phase boundary to decouple d₃₃ and ε_r.     

Mechanical and ablative properties improvement of HfC-SiC coatings upon introduction of TiC

A novel structural Hf-Ti-Si-C multiphase solid solution coating was designed and manufactured by chemical and solid solution reactions to improve the mechanical and ablation behavior of HfC-SiC coatings. Results show that, with TiC addition, the formed Hf_xTi_1?xC and (Ti_1?xHf_x)₃SiC₂ solid solutions can significantly enhance the micro-mechanical and ablation properties of the coating. The improved hardness and modulus, as well as the reduced ablation rates are mainly attributed to the optimized structure and solid solution reinforcing effect of coating. Moreover, the Ti-additives are conducive to restrain the active oxidation of SiC. Furthermore, HfTiO₂ can reduce the oxides cracking due to the inhibited crystal transformation of HfO₂ and its good self-healing ability, forming a dense and stable oxide scale with superior thermal protection.     

老化温度和老化时间对环氧酯漆涂层性能的影响

运用电化学阻抗谱(EIS)和Fourier变换红外光谱研究了经过不同老化温度和老化时间处理的含锌铬黄防锈颜料的环氧酯漆在3．5％NaCI溶液中的阻抗谱特征，根据Fourier变换红外光谱和电化学阻抗谱中第二个时间常数出现的快慢及高频收缩情况来判断涂层的耐蚀性能，进而筛选老化工艺．结果表明，当老化温度为80℃和140℃，老化时间为3周时，涂层耐蚀性较好．其老化过程实际是有机高分子进一步发生交联反应和分子键破坏相互竞争的过程．同时提出了锌铬黄防锈颜料的作用机理。