Evolution analysis of a UAV real-time operating system from a network perspective

With the flourishing development of Unmanned Aerial Vehicles (UAVs), the mission tasks of UAVs have become more and more complex. Consequently, a Real-Time Operating System (RTOS) that provides operating environments for various mission services on these UAVs has become crucial, which leads to the necessity of having a deep understanding of an RTOS. In this paper, an empirical study is conducted on FreeRTOS, a commonly used RTOS for UAVs, from a complex network perspective. A total of 85 releases of FreeRTOS, from V2.4.2 to V10.0.0, are modeled as directed networks, in which the nodes represent functions and the edges denote function calls. It is found that the size of the FreeRTOS network has grown almost linearly with the evolution of the versions, while its main core has evolved steadily. In addition, a k-core analysis-based metric is proposed to identify major functionality changes of FreeRTOS during its evolution. The result shows that the identified versions are consistent with the version change logs. Finally, it is found that the clustering coefficient of the Linux OS scheduler is larger than that of the FreeRTOS scheduler. In conclusion, the empirical results provide useful guidance for developers and users of UAV RTOSs.     

空间引力波探测微牛电推进寿命评估研究现状

阐述了空间引力波探测任务中无拖曳控制技术对推进系统的特殊要求，介绍了目前主要的备选推进类型：冷气推进、离子电推进、会切型霍尔电推进、胶体电推进。针对面向空间引力波探测任务的电推进系统的寿命评估工作进行了任务分析，报告了目前微牛级电推进系统寿命试验研究现状，举例说明了目前主要应用的电推进装置寿命预测方式，包括半经验模型预测、数值模拟预测、基于数据驱动的预测以及系统层面的可靠性评估方法。对目前微牛级电推进系统的寿命评估研究现状进行总结，给出了发展思路。     

Cortical Microtubule Reorientation and Its Relation to Cell Surface Texture of Epidermal Cells of Arabidopsis Thaliana Hypocotyls under Simulated Microgravity Conditions

Gravitropic curvature growth of Arabidopsis hypocotyls mainly occurred in the rapid growing Elongation Zone (EZI), not in the slow-growing Elongation Zone (EZⅡ). By examining reorientation of Microtubules (MT) and phenotype of the cell wall in the EZI and the EZⅡ of Arabidopsis hypocotyls under normal gravitational condition, it is found that MTs in the rapid growing epidermal cells were mainly in the transverse direction, while those in the non-growing epidermal cells were in the longitudinal directions. However, this difference in cortical MT arrays between the EZI and EZⅡ cells disappeared when the seedlings were exposed to the simulated microgravity condition on a horizontal clinostat. Field emission scanning electron microscopy revealed that the surface texture of epidermal cells, like the direction of the MT, in the EZI and the EZⅡ also became similar when exposed to the simulated microgravity condition. This result indicated that simulate microgravity could modify the potential differentiation between the EZI and the EZⅡ by affecting the orientation of cortical MT in the epidermal cells.      

基于过程方法的测量设备控制

测量设备控制是企业内部管理和外部质量管理体系审核中的一项重要内容,在现有的管理中,因缺乏对相关过程进行系统识别,某些过程要素常被疏忽或遗漏,导致测量设备失控和测量结果失准。本文采用过程方法,系统地识别了测量设备控制的相关过程和过程要素,提出了过程监控指标及其评价准则,对于提高过程效率具有一定的参考价值。     

基于激光旋切法的陶瓷材料盲孔加工方法研究

介绍了激光打孔的基本原理,对激光能量、离焦量、轨迹在激光旋切法加工盲孔过程中对孔形和表面质量的影响进行了分析和试验验证,并给出了一般规律.依据试验结果确定了合理工艺参数,采用旋切法在碳纤维增强碳化硅陶瓷基复合材料（Cf/SiC）上打出了孔径为1 mm,孔深为1.1 mm,锥度小于15°的盲孔.     

中国环境零风险的影响因素研究——基于地区的视角

从地区视角研究了中国环境零风险.研究认为,包括青海、内蒙古、陕西、上海、浙江以及江西在内的六个地区在中国环境零风险的形成中起了重要作用.因此,提出以下建议:第一,严格控制企业生产行为和人们生活行为相伴污染物的产出以及排放；第二,继续加大力度,鼓励企业生产行为、人们生活行为以及废物处理中使用环境友好型技术并对其进行创新；第三,根据不同地区的特点采取针对性的管理.     

Crystal orientation and morphology of α lamellae in wrought titanium alloys: On the role of microstructure evolution in β processing

To obtain high-quality aviation forgings of titanium alloys, β forging is an essential processing step which must be considered throughout a production process. In this work, the effect of β forging on the crystal orientation and morphology of lamellar α was experimentally investigated in a two-phase titanium alloy. Strong dynamic recovery during β working resulted in the formation of low-angle grain boundary (LAGB_β) inside β grains. The lamellar α can penetrate through the LAGB_β, leading to similar intra α LAGBs on subgrain boundaries. Deformation banding occurs at high strain rates, and both diffusive and sharp boundaries of deformation bands can be observed. A continuous change of the β orientation in diffusive boundaries results in the formation of fine and disordered α lamellae without intra-lamellar boundary to hold the Burgers orientation relationship (OR). On sharp boundaries, it is prone to producing continuous grain boundary α (α_GB) with a highly similar orientation along the boundaries. Meanwhile, there may exist several lower-angle boundaries within the grain boundary α for a smoother orientation change on the β grain boundary.     

风扇出口导向叶片低噪声设计Ⅰ:方法与优化

作为"风扇出口导向叶片（Outlet Guide Vanes，OGV）低噪声设计"系列文章的第1篇，本文在现有压气机气动设计流程的基础上，加入了噪声评估过程，建立了基于通流设计的气动/声学一体化设计方法。为提高设计阶段的评估速度，以三维升力面理论与管道声学理论为基础，从通流设计和造型设计输出中提取参数，结合转子尾迹模型，建立了转/静干涉噪声的解析预测模型。以现代大涵道比涡扇发动机风扇/增压级为对象，采用该模型系统分析了OGV轴向掠形与周向倾斜对转/静干涉噪声的影响，获取了轴向掠形角与周向倾斜角等三维设计参数与风扇噪声的关系图谱，初步确定了低噪声设计较优降噪量的掠和倾组合方案。以此为基础，在保持叶尖子午投影位置和弦长不变的前提下，将叶片前缘和径向积叠进行参数化，采用遗传算法进一步开展了OGV的低噪声优化设计，最终获得了2个优化方案，预估的降噪量达到了8 dB。     

基于TTE网络的分布式系统分区通信方法

针对新一代分布式IVMS及高可靠航电系统对通信网络的确定性通信要求，分析了符合ARINC653标准的分区间通信原理，研究TTE端系统缓冲方案，设计了分区间TTE通信映射配置，实现了分区间TTE通信驱动，建立了分区间TTE通信测试平台，通过实际测试表明，基于TTE网络的分布式系统分区通信方案有效可靠。     

终端区飞行程序与军航起落航线安全风险分析

为了对终端区内民航进离场程序与军航机场起落航线间的安全风险进行分析,提出了一种基于计算几何的两阶段三维分析方法。首先对终端区空域进行建模,并利用军航机场起落航线保护区确定军航机场活动范围。在此基础上,第一阶段利用计算几何方法分析军航机场活动区与进离场航线间在二维上是否存在安全风险;第二阶段利用Route距离分析在二维上存在安全风险的程序段与军航机场活动区的垂直安全间隔。以国内某终端区为例进行了实例分析,证明方法能科学高效地对进离场程序与军航机场起落航线间安全风险进行三维空间分析。