^(137)Cs,^(60)Co大面积航空平面源的制备技术CSCD

用于校准航空γ谱仪的137Cs,60Co大面积航空平面源对传统的涂刷制源技术提出了挑战,为确保平面上的均匀性,借鉴现代网格点阵喷涂技术,将137Cs,60Co两种放射性标准溶液分别定量滴注在底衬滤纸上,晾干后热塑封并用环氧树脂将塑封片固定在梯形铝板上,由8块梯形铝板拼接为边长1m的正六边形航空平面源。制备的航空平面源的扩展不确定度(k=2)为4%,不均匀性优于10%。     

Microstructure and Martensitic Transformation Behaviors of Explosively Welded NiTi/NiTi Laminates

The study is a first attempt to prepare bulk NiTi/NiTi shape memory alloy (SMA) laminates with a macroscopic heterogeneous composition by explosive welding and investigate their microstructures and martensitic transformation behaviors. After explosive weld- ing, a perfect interfacial bonding between the two components and a reversible martensitic transformation are realized in the tandem. Results show achievement of a fine granular structure and the maximum value of microhardness near the welding interface because of the excessive cold plastic deformation and the high impact velocity during the explosive welding. Meanwhile, the effects of aging on the transformation of the welded tandem are investigated by differential scanning calorimeter (DSC) and subject to discussion. The trans- formation temperatures of NiTi/NiTi SMAs increase with the rise of the aging temperature. The experimental results indicate the shape memory properties of NiTi/NiTi SMA fabricated by explosive welding can be improved by optimizing the aging technology.     

Electrolytic Passivation of Nitinol Shape Memory Alloy in Different Electrolytes

The corrosion behavior of the nitinol alloy was studied in various corrosion media of different Cl–ion concentrations. The results demonstrate that the Cl–ion concentration has significant influences on the corrosion behavior of the nitinol alloy. In order to enhance the corrosion resistance, protective films were generated on the surface of the nitinol alloy by means of the electrochemical passivation method, for which five different electrolytic solutions were investigated. The surface analysis indicates full growth of all samples pas-sivated in the different electrolytic solutions with layers, however, showing different morphological features. Without any defects like micro-cracks and pores, the surface of the samples passivated in the molybdate solution turns out smoother and denser than those pas-sivated in other solutions. It is shown that the electro-chemical passivation will reduce Ni content but increase Ti content in the surface, reaching the Mole ratio of Ti:Ni=9.01:1 on the outermost surface. Potentiodynamic polarization test demonstrates that the samples electrochemically passivated in the molybdate solution present a significant increase in breakdown potential due to titanium enrichment on the outermost surface.     

新舟60飞机起飞性能分析

从新舟60(MA60)的飞机飞行手册(AFM)和飞行机组操纵手册(FCOM)入手,分析了限制最大起飞重量的因素和起飞速度的选择方法,着重讨论了MA60最大起飞重量的限制因素,并以MA60从广汉至兰州的航线飞行为例分析了最大起飞重量和起飞速度的确定方法。     

斜置尾桨对直升机飞行特性的影响

基于叶素理论建立了斜置尾桨的数学模型,以UH-60A直升机为对象,计算了平飞配平特性,并与试飞结果进行对比,完成了对模型的验证。验证结果表明,所建的斜置尾桨模型合理准确,能满足工程精度。本文从直升机悬停需用功率研究了尾桨斜置角的设计,计算了不同尾桨斜置角对直升机悬停需用功率的影响,得出UH-60A直升机的尾桨斜置角优化值为20~25°。通过计算和对比斜置尾桨与常规尾桨直升机的平飞配平特性,得出尾桨斜置主要影响直升机的纵向配平特性。最后,对斜置尾桨的利与弊进行了一些讨论。     

振动时效对NiTi记忆合金双程记忆应变的影响

研究了振动时效对NiTi形状记忆合金双程记忆效应的影响.结果表明,当预应变较小或较大时,经过振动时效后NiTi合金的双程应变量增加;当预应变适中时,振动时效后NiTi合金的双程应变量减小.这可能是由于振动时效在NiTi合金中产生了微观塑性变形,改变了合金中的双程应力场而导致的.     

Ni,Ti及NiTi合金低能电子散射的Monte Carlo模拟

采用MonteCarlo方法,模拟了低能电子束(能量E0≤5keV)作用下Ni,Ti及NiTi合金固体中的电子散射,分析了3种金属/合金中散射电子的能量与空间分布。研究表明:(1)入射电子能量E0越小,各材料的背散射电子(BSEs)深度、吸收电子(AEs)深度及散射电子能量损失的深度均越小,分辨率越高;(2)相同E0下,各材料的BSEs,AEs及能量损失深度均有NiNiTi>Ti;(3)NiTi合金的BSEs深度、AEs深度及能量损失的深度和分辨率分别近似于Ni,Ti固体相应量的平均值。     

Investigation of longitudinal aerodynamic parameters identification method for fly-by-wire passenger airliners

The flight control system of a fly-by-wire （FBW） passenger airliner with a complex frame-work and high feedback gain augmentation would change the original characteristic of a loaded signal and suppress the excitation of an airplane＇s pertinent motion modes. Taking a research example of an FBW passenger airliner model with longitudinal relaxed-static-stability, a new method of signal type selection and signal parameter design is proposed, through analysis of signal energy distribution and plane body＇s frequency response. According to CCAR60--the Appraisal and Use Regulation of Flight Simulator Device, the simulation validation of the FBW passenger airliner＇s longitudinal aerodynamic parameters identification is put forward. The validation result indicates that the designed signal could excite the longitudinal motion mode of the FBW passenger airliner adequately and the multiparameter comparison in simulation meets the objective test request of CCAR60. Meanwhile, the relative errors of aerodynamic parameters are less than 10%.     

前进速率对搅拌摩擦加工ZK60镁合金组织和力学性能的影响

对铸态ZK60镁合金进行搅拌摩擦加工,在转速为800r/min,前进速率为50~200mm/min的条件下,获得表面平整、无宏观缺陷的材料,并对其组织和力学性能进行研究。研究结果表明:剧烈的塑性变形使搅拌区的晶粒相对于铸态母材得到了明显细化,随着前进速率的增加,搅拌区平均晶粒尺寸先减小后增大。搅拌区细晶组织的显微硬度及抗拉强度相比于铸态母材有所提高,而伸长率显著提高。在转速为800r/min,前进速率为100mm/min的加工条件下,搅拌区的晶粒最为细小均匀,其平均晶粒尺寸为6.9μm,材料的硬度、抗拉强度和伸长率分别为70.1HV,276 MPa和31.6%。     

PowerPC架构的中央处理器模块在线检测技术研究

论述了一种以PowerPC750作为硬件架构的中央处理器模块在线检测技术,利用模块自身运行的启动、加载检测程序和VxWorks实时操作系统的调试工具完成高集成度复杂电路板故障的在线检查与测试。相比传统的离线测试方法,在线检测技术不仅能够更加准确、快速地定位故障;而且可以避免离线测试时对电路板再造成二次损伤。