Although it is acknowledged that using periodically heterogeneous film can improve adhesion properties without interface modification, there is still a lack of comprehensive research in the existing literature that specifically investigates the behavior of peeling of such film from rigid substrate at arbitrary peeling angle. To this end, two theoretical models, an accurate and an approximate model, for the peeling of periodically heterogeneous film at arbitrary peeling angle are proposed in this study. The primary focus of the present study is on examining the peeling behavior of such film, with special attention given to the impact of peeling angle on the peeling behavior. Our analysis revealed two unknown peeling behaviors. Firstly, the use of periodically heterogeneous film not only enhance the adhesion performance of its stiff section, but also weakens the adhesion performance of its compliant section. Secondly, the enhancing ratio of adhesion performance does not remain constant, nor does it exhibit a monotonically increasing function with the peeling angle. Instead, it initially increases and then decreases as the peeling angle increases. The weakening ratio of adhesion performance with respect to the peeling angle is similar to that of the enhancing ratio. The influence of several parameters, including the bending stiffness ratio, adhesion energy, bending stiffness of the compliant section, period length of the periodically heterogeneous film, and length fraction of the stiff section, on the peeling of periodically heterogeneous film at arbitrary peeling angle are also studied. Based on the accurate theory, a formula for calculating the peeling force of homogeneous film is also derived. The calculated results using the proposed formula are in excellent agreement with the classical Kendall theory

Although it has been demonstrated that heterogeneous film can enhance adhesion properties without modifying the interface, there is still a dearth of comprehensive studies in the literature regarding the peeling process of such film and the potential instability that may occur during the peeling process. To address these issues, a peeling model based on the cohesion zone model and Euler-Bernoulli beam equation is proposed in this study. Our analysis revealed four previously unknown peeling behaviors: Firstly, there are nine kinds of peeling processes for heterogeneous film. Only one is stable, static peeling process, while the other eight exhibit instability when the peeling front reaches a certain position. Secondly, instability may occur at the interface from the stiff section to the compliant section of the homogeneous film, as well as at stiff section or compliant section. Moreover, two of these peeling processes experience two instabilities within one peeling period - one at the interface from the stiff section to the compliant section and another at stiff section. Thirdly, an optimal length fraction of the stiff section for enhancing adhesive performance exists and its value is largely determined by the strength of the interface material. Specifically, higher interfacial strength results in smaller values of the optimal length fraction. Finally, the maximum peeling force is positively correlated with the bending stiffness ratio, interfacial strength, interfacial toughness, and period length of heterogeneous film. But it is inversely related to the bending stiffness. These findings are crucial for understanding the peeling behavior of heterogeneous film and strongly adhesive interfaces found in nature, and can be applied to optimize adhesive design and performance in practical engineering applications.

Application of an external tensile displacement at the end of an elastic film induces its peeled from the free (fixed) end of the cantilever flexible substrate to the fixed (free) end of it. This work proposes a theoretical model for studying this simple elastic system. The analysis results for the film peeled from free end to fixed end (FRFI) demonstrate a number of unknown and unexpected behaviors: (i) There are five basic types of peeling form depending on the flexural rigidity of the substrate, the elastic modulus and thickness of film and adhesive energy; (ii) Some peeling forms have two peeling states (the substrate has two deformed shapes and the pulling force has two values when the film is peeling off) for certain peeling front; (iii) When the film is peeled to a certain place, unstable dynamic peeling will occur. In comparison to FRFI, the results of the film peeled from the fixed to free end (FIFR) appear natural. The effect of flexural rigidity and adhesive energy on the peeling behavior of FIFR is larger.

行冲突解脱是空中交通管理中一个关键问题.分析了机载TCAS的冲突探测原理和ADS-B IN技术的特点,考虑飞行动力学、气象、人为因素等多种随机因素,建立了概率型冲突预测和解脱模型.针对同一空域内所有目标机进行跟踪和分类,将冲突区域网格化,利用改进遗传算法快速搜寻最优无冲突航迹,最大程度地减少偏离原航线的距离,并最终引导飞机回到既定航线,提高飞行效率和安全.通过仿真计算验证了模型和算法的有效性,在采用定步长航向调整策略结合速度调整策略效果显著,在航空防撞设备中具有很好的应用前景.

"高度"和"空间"概念在空中交通管理课程中成为关键角色,受困于工具的局限,学生在概念掌握和实习实践方面难以获得满意效果,虚拟现实技术的出现很好地解决了空中管理课程的教学难点.该文针对课程特点,分析了虚拟现实技术用于空中交通管理课程的意义和应用模式,为民航人才培养和教育模式改革创新提供了借鉴和参考.

随着高校不断深化工程专业人才教育改革,从"新工科"的教育理念出发,结合民航运输业发展需要,分析了空管与签派专业人才培养要求,总结了民航院校空管与签派专业实验实训平台存在的问题,明确了基于真实场景的实验实训项目建设的要求,并针对问题及要求提出了空管与签派实验实训平台建设的对策和措施,为培养实践能力强、素质高的新复合型民航技术人才奠定基础.

近年来民航业快速发展,空中交通流量日益增大,自由飞行成为区域和支线航空发展的趋势.自由飞行环境下安全评估研究将是保障飞行安全和提高效益的一项关键技术.采用动态加权综合评价方法,分析两机相对运动状态,将相对距离和速度在分别分为x轴方向、y轴方向、和z轴方向的6个指标表示飞机的空间位置关系和运动情况,进而精确地评价飞机的危险性大小.通过仿真计算了飞机和时间节点数的危险系数矩阵,利用决策分析中的Borda函数方法进行排序,得出总排序结果,验证了模型的有效性.研究在空中交通防撞系统中具有较好的应用前景.

签派放行工作作为航空公司运行管理的中枢,其安全水平对航空安全起着决定性作用,运用DEM A T EL-ISM法对签派放行中人为因素影响进行建模分析.首先,基于已有研究并与专家讨论构建签派放行中人为因素体系.接着求出各因素之间相互影响关系,划分因素体系层次结构.最后提出改进建议.结果表明规章管理制度与教育培训为本质致因因素,且与企业理念同为关键因素,在因素体系中既与其他因素较为密切的联系且影响着其他因素,又有较高的重要程度.

近年来,河南省以郑州航空港经济综合实验区建设为契机,大力发展通用航空产业.目前河南省已拥有两个通航产业园区,数十家通航企业,近百架航空器.在通航产业迅速发展的同时,因通航飞行服务体系不健全,通航企业的发展受到了严重制约.文章着重介绍了四家有代表性的河南通航企业的发展现状,分析了河南通航飞行服务存在的主要问题;结合河南空管局管制、气象和通信等人力资源现状,设计河南通用航空飞行服务站.提出优化通航任务申报程序,完善飞行服务体系的建议.