国外空间大型网状天线在轨展开故障与对策

空间大型网状天线在轨可靠展开是确保航天任务取得成功的关键。对国外自1974—2011年间发射的部分科学、商业和军用航天器携带的大型网状天线在轨展开故障情况进行了统计,介绍了各天线展开故障的机理,并对天线展开故障应急处理方法和设计改进措施进行了总结。根据空间大型天线展开的特点,提出了加强天线抗冲击能力、充分开展天线机构实验验证和展开故障应急处理预案研究等建议。     

网络技术在高校统计工作中的运用

在高校竞争日趋激烈的形势下,离不开“快、精、准”的统计信息。网络技术在统计资料的收集、科学管理和分析处理方面具有明显的优势。把网络技术运用到高校统计工作中,全面提高统计质量与统计信息的使用效率,是当前统计工作面临的重要问题。     

Overview of current design and analysis of potential theories for automated fibre placement mechanisms

Automated fibre placement(AFP) systems have successfully intensified the demand for high-quality composite component manufacturing in both the military and civilian fields. One of the main elements of these systems is the AFP mechanism for accomplishing individual fibre delivery,clamp/cut/restart(CCR) and the consolidation process, and it consists of several functional submechanisms presenting strong coupling relationships and motion sequences. This review aims to summarize the development of AF...     

Effect of gap and overlap on mode Ⅱ interlaminar fracture toughness of automated fiber placement prepreg laminates

Automated Fiber Placement(AFP) technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However,the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the mode Ⅱ interlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End...     

Contributions to data transmission at critical moments on unmanned aerial vehicles

As for unmanned aircraft, the knowledge of the aircraft performance is directly related with the navigation, guidance, and control system programming. Therefore, the measured data in each phase of the flight must be sufficiently precise to obtain a good characterization of aircraft. This article proposes new methods of sending information to ground, which make it possible to know the aircraft behavior accurately, and for this purpose, four contributions have been made for ALO (Avión Ligero de Observación, Spanish acronym for Light Observation Aircraft). Currently, the characterization is based on data obtained at ten samples per second, insufficient to acquire detailed knowledge of what happened during the whole flight of an aircraft. As a result of these contributions, many more samples per second of accelerations and angular velocities are obtained at the most critical moments of the flight, such as takeoff or landing. Among the improvements included are data compression techniques, providing references to locate the measured data in time and identifying labels of each parameter.