直升机桨叶耐颗粒物/砂磨蚀标准分析

在分析研究直升机桨叶耐颗粒物/砂磨蚀标准主要技术要素的基础上,全面对比分析了MIL-STD-3033、ГОСТР52560-2006、GJB 1171-1991等国内外标准的基本内容,提出了装备研制及标准化工作相关建议。     

新型弹簧床结构的HAN基发动机技术

为改善硝酸羟胺(HAN)基发动机催化剂在长时间工作的工况下容易发生破碎而产生空穴的现象，本文提出一种新型弹簧床结构发动机设计方法，对发动机催化床进行改进优化设计。该设计可实现，常温环境下弹簧所提供的最大弹力不足以压碎催化剂；同时在高温环境下，弹簧的最小弹力足以克服催化床受到的流动阻力，可大幅提高发动机工作寿命、性能和可靠性。为验证该设计方法的有效性，分别开展了传统结构和新型弹簧床结构的HAN基1N发动机温启动试验。试验结果表明：在相同试验条件下，传统结构1N发动机温启动次数不超过150次，而使用新型弹簧床结构的1N发动机温启动次数超过了500次，且工作性能更优。试验结果证明了该设计方法的有效性，为HAN基发动机长寿命可靠工作奠定了良好的技术基础。     

飞机研发中的企业浪费与信息化对策

企业中错综复杂的问题都以各种各样的浪费形式表现出来。如何透过这些表象将正处在改革过程中的企业产品研发中的问题症结找出来,通过信息技术的深层次应用和知识管理在企业的推动,将这些问题解决、最大限度地减少浪费,是我们需要研究的一项重要课题。     

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.     

基于乙炔基封端酰亚胺和氰酸酯树脂的互穿网络聚合物

以2，3，3'，4'-联苯四甲酸二酐和2，2'-双三氟甲基-4，4'-联苯二胺为单体、4-乙炔基邻苯二甲酸酐为封端剂合成了不同聚合度的聚酰亚胺低聚物（BETI），将其溶于双氛A型氰酸酯单体制备了改性氰酸酯树脂，对改性氰酸酯树脂的固化行为进行了详细探究，并对其固化物的热学性能、力学性能和介电性能等进行了表征与分析。结果表明:BETI对氰酸酯树脂的聚合有明显的催化作用，可以降低固化温度，缩短凝胶时间。基于BETI和氰酸酯树脂的互穿网络聚合物（IPN）的热性能和力学性能与纯氰酸酯树脂相比都有一定的提高。当加入质量分数30%、聚合度为19的BETI树脂时，固化物的玻璃化转变温度从297 ℃提高到309 ℃，热失重5%时温度从425 ℃提高到了431 ℃；拉伸强度从76 MPa提高到了94 MPa，冲击强度从24 kJ/m2℃提高到了31 kJ/m2。加入BETI后，聚合物的介电常数稍稍高于纯氰酸酯树脂。由于具有良好工艺性和材料性能，BETI改性氰酸酯树脂可作为基体树脂应用于航空航天等领域。      

Temperature effect on buckling properties of ultra-thin-walled lenticular collapsible composite tube subjected to axial compression

This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube(LCCT) subjected to axial compression.The buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500 N servo-hydraulic machine in dry state and at the temperatures of 25 C, 100 C and 80 C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of 80 C than at the room temperature of 25 C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element(FE) model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.     

A parameterized geometry design method for inward turning inlet compatible waverider

Intensive studies have been carried out on generations of waverider geometry and hypersonic inlet geometry. However, integration efforts of waverider and related air-intake system are restricted majorly around the X43A-like or conical flow field induced configuration, which adopts mainly the two-dimensional air-breathing technology and limits the judicious visions of developing new aerodynamic profiles for hypersonic designers. A novel design approach for integrating the inward turning inlet with the traditional parameterized waverider is proposed. The proposed method is an alternative means to produce a compatible configuration by linking the off-the-shelf results on both traditional waverider techniques and inward turning inlet techniques. A series of geometry generations and optimization solutions is proposed to enhance the lift-to-drag ratio. A quantitative but efficient aerodynamic performance evaluation approach （the hypersonic flow panel method） with lower computational cost is employed to play the role of objective function for opti- mization purpose. The produced geometry compatibility with a computational fluid dynamics （CFD） solver is also verified for detailed flow field investigation. Optimization results and other numerical validations are obtained for the feasibility demonstration of the proposed method.     

空域拥挤风险管理时间决策模型与方法

针对目前日益严重的空域拥挤现象,缺乏有效的空域拥挤风险管理机制,造成拥挤难以应对等问题,建立了空域拥挤风险预测模型、空域拥挤风险解决模型和风险损失成本模型。采用风险预测模型和解决模型预测可能产生空域拥挤的时段、提出不同时段的实施流量管理策略,基于风险损失成本模型给出了不同时段调整拥挤的运行成本,通过比较运行成本和空域拥挤风险管理决策方法确定出解决空域拥挤的最佳时间点。采用实际运行数据进行验证,结果表明:所建立的空域拥挤预测模型、空域拥挤风险解决模型、风险损失成本模型和空域拥挤风险管理时间决策方法能有效地预测未来空域发生拥挤的时段,迅速找到运行成本最小的调整拥挤的时间点,为空中交通流量动态管理提供了新途径。     

Improving orbit prediction accuracy through supervised machine learning

Due to the lack of information such as the space environment condition and resident space objects’ (RSOs’) body characteristics, current orbit predictions that are solely grounded on physics-based models may fail to achieve required accuracy for collision avoidance and have led to satellite collisions already. This paper presents a methodology to predict RSOs’ trajectories with higher accuracy than that of the current methods. Inspired by the machine learning (ML) theory through which the models are learned based on large amounts of observed data and the prediction is conducted without explicitly modeling space objects and space environment, the proposed ML approach integrates physics-based orbit prediction algorithms with a learning-based process that focuses on reducing the prediction errors. Using a simulation-based space catalog environment as the test bed, the paper demonstrates three types of generalization capability for the proposed ML approach: (1) the ML model can be used to improve the same RSO’s orbit information that is not available during the learning process but shares the same time interval as the training data; (2) the ML model can be used to improve predictions of the same RSO at future epochs; and (3) the ML model based on a RSO can be applied to other RSOs that share some common features.