Multiple hierarchy risk assessment with hybrid model for safety enhancing of unmanned subscale BWB demonstrator flight test

To explore the low-speed characteristics of the Blended-Wing-Body (BWB) configuration for future civil aircraft, a series of unmanned subscale demonstrators have been developed and tested by our research team. During this process, specific safety risks deriving from uncertain design features, system unreliability, and insufficient personnel experience caused continuous flight test mishaps and the risk mechanism was not clear. Local and trial-and-error learning driven safety improvements took few effects on mishap prevention, so our focus was turned to look for systematic safety strategies. This paper establishes a systems theory based hybrid model to integrate the physical system reliability analysis techniques with the system dynamics method for illustrating the multiple risk interactions of the demonstrator flight test involving organizational, human resource and technical system factors. Using the prior BB-5 demonstrator as a case, the hybrid model simulation represents its historical risk evolution process, which verifies the model rationality. Derived risk control strategies reduced the mishap rate of a new demonstrator called BB-6 Sprit. The paper also shows the extended hybrid model can be applied on safety management of unmanned aerial vehicles from the initial period of vehicle development.     

总体结构优化在导弹总体设计中应用

作为导弹总体设计的一项重要内容，结构总体设计优劣影响着导弹最佳总体技术方案成败。现根据型号研制的工程经验，提出了应用于结构总体设计的总体结构优化方法。结合实例，着重从结构最优布局、动力学优化和运动学分析等三方面阐述了具有并行设计特点的总体结构优化内涵。研究表明，总体结构优化是基于并行工程框架的数字化定义、数字化预装配和分析、仿真一体化设计，是解决导弹结构轻质化、提高导弹总体设计水平的有效途径。     

二阶被控对象PDF控制器设计的新途径

介绍一种响应速度快、无超调、鲁棒性强、抗干扰性能好的控制策略--PDF(Pseudo-Derivative-Feedback)控制,并提出一种设计PDF控制器的新途径.数字仿真结果表明,同传统的Cascade-System法(亦称Phelan法)和Single-System(亦称陈留法)一样,在有功率元件输出功率限制的情况下,用这种新方法所设计的控制器能够使系统实现较好的响应性能.     

金属基复合材料(MMC)的理化行为和工程性

文章就金属基复合材料(MMC)的理化特性和工程技术应用进行简要叙述,例举了近些年国内外该领域的科研动态,并对金属基复合材料(MMC)的应用前景尤其是在航空、航天工程中的推广和发展提出了看法。     

翼伞技术研究的最新发展

当今美国对翼伞的研究非常活跃,涉及的面非常广,内容也很丰富,其中包括研制特种新型翼伞、空投重物的大面积翼伞、用GPS(全球定位系统)为导航仪的定点着陆控制技术、翼伞操纵训练的计算机仿真、翼伞的竞技运动及其他应用技术等。文中将重点介绍三项可借鉴的最新成果。首先,介绍一种新概念的全封闭前缘后掠翼伞,内容涉及到该种翼伞的展弦比、结构参数、材料、开伞、充气动态性能、有效载荷、机动性等。其次,介绍模拟机的研制,该机成为跳伞运动员专业教学训练的新工具,还可为先进的精确机载回收系统提供仿真,从而有机会全面了解风、有效载荷对控制的影响。最后,介绍在美国高滑翔回收系统中,具有新里程碑意义的GS—750—1翼伞,由于不断的改善性能,提高精度,从而能自动降落到离中心目标100m之内的地方。     

Silkworms culture as a source of protein for humans in space

This paper focuses on the problem about a configuration with complete nutrition for humans in a Controlled Ecological Life Support System (CELSS) applied in the spacebases. The possibility of feeding silkworms to provide edible animal protein with high quality for taikonauts during long-term spaceflights and lunar-based missions was investigated from several aspects, including the nutrition structure of silkworms, feeding method, processing methods, feeding equipment, growing conditions and the influences on the space environmental condition changes caused by the silkworms. The originally inedible silk is also regarded as a protein source. A possible process of edible silk protein was brought forward in this paper. After being processed, the silk can be converted to edible protein for humans. The conclusion provides a promising approach to solving the protein supply problem for the taikonauts living in space during an extended exploration period.     

What is wrong with space system cost models? A survey and assessment of cost estimating approaches

Despite several decades of research and refinement in cost estimating tools and practices, the final cost of US space programs continues to exceed initial cost estimates by an average of more than 45%. Thus, program cost models not only exhibit error, they are seriously biased. A structured review surveyed techniques, approaches, models and conceptual tools related to space program cost estimating, to understand cost in complex space systems. Analysis shows problems of cost estimating result from the growing complexity of space programs, failures in managing growth, and mission failures. Although there is greater expectation for the models to accurately predict program costs, the current models used for seeking funding for large space programs are inadequate due to (1) inability to predict future, (2) lack of insight, and (3) process replaces judgment in decision making.     

CCSDS空间网络互联协议发展及启示

空间互联网将是由各种区域网构成的复杂异构网络,为了使其能够逐步实现自动化运行,网络效益得到最大程度的发挥,须做好网络互联的顶层规划与设计,并开发具体的标准技术.根据近年CCSDS (Consultative Committee for Space Data Systems,空间数据系统咨询委员会)发布的建议书,以及相关工作组的项目规划情况,介绍了SSI(Solar System Internetwork,太阳系互联网)体系结构、IPoC(IP over CCSDS space links,在CCSDS空间链路之上承载IP),以及DTN(Delay Tolerant Networking,容延迟网络)等标准项目.从CCSDS空间网络互联技术的发展历程不难得出结论:我国未来空间网络互联应注重区域网之间互联的顶层设计;区域网内部各子网之间的互联技术应选择以航天任务需求牵引为主;DTN将在区域网之间互联以及区域网从简单到复杂发展中都发挥重要作用.     

High-efficiency aircraft antiskid brake control algorithm via runway condition identification based on an on-off valve array

The aircraft antiskid braking system is an important hydraulic system for preventing tire bursts and ensuring safe take-off and landing. The brake system adjusts the force applied on the brake discs by controlling the brake pressure. Traditional aircraft antiskid braking systems achieve antiskid performance by controlling the braking pressure with an electrohydraulic servo valve. Because the pilot stage of an electrohydraulic servo valve is easily blocked by carbonized hydraulic oil, the servo valve would become a dangerous weak point for aircraft safety. This paper proposes a new approach that uses an on-off valve array to replace the servo valve for pressure control. Based on this new pressure control component, an efficient antiskid control algorithm that can utilize this discontinuous feature is proposed. Furthermore, the algorithm has the ability to identify the runway circumstances. To overcome the discontinuity in the process of using an on-off valve array, the Filippov framework is introduced. The conditions of convergence of the system are also discussed. The results of the digital simulations and the hardware-in-the-loop (HIL) braking experiments are used to verify the efficiency and stability of the proposed control algorithm. The method also proves that the on-off valve array can replace the servo valve perfectly as a new type of antiskid braking pressure control component.     

Fronts and thermohaline structure of the Brazil–Malvinas Confluence System

Fronts and thermohaline structure of the Brazil–Malvinas Confluence System (BMCS) are studied from climatic data, “Marathon Exp. Leg.8, 1984” data, and Sea surface temperature (SST) data base “ds277-Reynolds” (1981–2000). The South Atlantic Central Water (SACW) is divided in two main types: tropical (TW) and subtropical water (ST). Water masses, Fronts, Inter-Frontal and Frontal Zones are analysed and classified: (a) the water masses: Tropical Low-Salinity Water, Tropical Surface Water, Tropical Tropospheric Water, Subtropical Low-Salinity Water, Subtropical Surface Water, Subtropical Tropospheric Water. T,S characteristics of intermediate, deep and bottom water defined by different authors are confirmed and completed; (b) the Inter-Frontal Zones: Tropical/Brazil Current Zone, Subtropical Zone and Subantarctic Zone; (c) the Frontal Zones: Subtropical, Subantarctic and Polar, and (d) the Fronts: Subtropical Front of the Brazil Current, Principal Subtropical Front, North Subtropical Front, Subtropical Surface Front, South Subtropical Front, Subantarctic Surface Front, Subantarctic Front and Polar Front. Several stable T–S relationships are found below the friction layer and at the Fronts. The maximum gradient of the oceanographic characteristics occurs at the Brazil Current Front, which can be any of the subtropical Fronts, depending on season. Minimum mean depth of the pycnocline coincides with the Fronts of the BMCS, indicating the paths of low-salinity shelf waters into the open ocean. In the work it is shown how to recover the horizontal and vertical thermohaline structure of waters from satellite data RSMAS SST.