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.     

关于图论中Woodall猜想的研究

本文通过对图论中Ｗｏｏｄａｌｌ提出的一个问题进行研究。     

Effect of surface roughness on microwave brightness temperature from lunar surface: Numerical analysis with a hybrid method

A hybrid method, combining the radiative transfer theory and the method of moments (MoM), is proposed to study the potential effect of the lunar surface roughness on the microwave brightness temperature. The total upward emission reaching the lunar surface from below media is calculated by the radiative transfer theory, and then the brightness temperature is obtained by weighting the bidirectional transmission coefficients which is computed using the MoM. The method is validated by both flat and rough surface models with analytic solutions. With the hybrid method, brightness temperatures from simulated lunar model are calculated and compared to those from a flat layered model. The comparisons show that the effect of rough surface on brightness temperature cannot be ignored and also depends on many other factors, such as observation angle and polarizations. For vertical polarization, an optimal observation angle may exist to reduce the effect of surface roughness. These results indicate that the knowledge of lunar surface roughness is important in microwave remote sensing to the Moon and may probably provide a guide to lunar projects in future.     

以作战结果向量分析飞机1对1空战效能

给出了作战歼击机作战结果向量模型，并以此作为衡量歼击机作虎效能的指标。通过战例分析，指出了抢先发射对提高飞机的作战效能起着重要的作用。并根据现代歼击机及其装备的飞行战术，技术特性，分析讨论了影响抢先发射以及作战结果向量的可能因素。给了的模型，可为新一代战斗机设计提供理论依据。     

飞行仿真中的机动生成器

讨论了作为数字飞行仿真计算中的关键环节的轨迹跟踪和指不乔量两种机动生成器的原理与应用，并根据常赠模型他机动生成器设计参数的选取问题，机动生成器由于采用统一的比例－积分－微分（ＰＩＤ）反馈形式，简化并改进了以往数字飞行仿真中有关环节的处理，在使用中具有良好的效果。     

典型直升机完整性维持关键技术需求分析研究

典型直升机是实施立体突击作战的重要力量，在火力支援、立体补给、综合勤务保障等方面发挥着重要作用。针对其构造形式和作战使用要求，直升机在低空超低空低速执行任务时，使用场景中面临低空和地面的多种威胁，致使其服役环境和作战环境更加恶劣。本文通过分析直升机在作战中面临的威胁特点，阐述在直升机设计和使用维护过程中，综合防护能力、环境适应能力、战伤抢修能力对直升机作战完整性的影响，通过合理设计机体结构，提升生存能力，提升海上、高原、沙尘等环境适应能力，建立完备的战伤抢修能力来保证直升机使用的完整性，满足使用需求。     

跨文化培训与外语教学

笔者结合跨国公司跨国经营成败的实例，分析了跨国公司对其海外经营人员进行跨文化培训的必要性，强调大学英语教学应该培养学生跨文化交际的能力，并探讨了在实施跨文化教学过程中应注意的问题。     

Adaptive backstepping-based flight control system using integral filters

A backstepping control design procedure for uncertain nonlinear flight control system expressible in parameter-strict feedback form is presented in this paper. The proposed backstepping procedure, in association with sliding model control technique, exploits the possibility of avoiding, under certain suitable assumptions, the overparameterization problem existing in the classical backstepping process. In particular, a sliding-model-based integral filter is introduced to facilitate the development of the derivation of the virtual inputs, thus reducing the computational load with regard to the standard backstepping procedure. Moreover, in simulations, the control parameters in the resulted controller are optimally tuned using a genetic algorithm so as to show the full potential of the proposed control system.     

频率捷变时间精密测试系统

较详细地介绍了捷变时间的定义以及６种常用测量方法的原理、数据处理过程、及测量结果等内容。６种方法分别为检相－示波器法、鉴频－示波器法、检相－时间间隔计数器法、鉴频一时间间隔计数器法，ＨＰ５３７２Ａ测频和ＨＰ５３７２Ａ测相。给出了这几种测量方法的适用范围和优缺点。