How to reasonably allocate unmanned aerial vehicle(UAV)search and rescue tasks in low-altitude rescue has been the focus of research for a long time.The multi-object UAV mission assignment model based on level and distribution assignment method is established.In the model,the search and rescue cost,the number of UAVs used,and the balance of completed tasks are used as objective functions,and solved with the improved NSGA-Ⅱalgorithm.The results show that the established model is effective,and the reasonable and effective allocation schemes can be given in different search and rescue environments.When the highest rescue efficiency are oriented,it will lead the cost and number of UAVs increase.As the actual search UAVs are very limited,the investment of time cost is required.When economic interests are oriented,it will lead to the conclusion that search and rescue time will increase.

航空器在场面滑行时会遇到追尾冲突、交叉冲突和对头冲突三种冲突类型,遇到不同冲突类型时航空器经历的滑行阶段不同.针对航空器场面滑行冲突特点,构建了航空器场面滑行三种冲突下的运动模型,并以此作为不同冲突类型下的运动约束.考虑以最小滑行时间、燃油消耗,以及污染物排放为优化目标进行场面滑行路径优化.通过对上海浦东机场实验结果表明:提出的方法可以提高滑行时间计算准确率,能够得到兼顾滑行效率和经济环保性的航班滑行路径.

为了提高直升机和无人机联合搜救中的直升机释放无人机位置准确性,在已经选取待搜救点基础上,以搜救的费用最小为目标建立通航直升机释放无人机位置模型,考虑无人机的电池容量约束,同时考虑风、地形,以及无人机状态进行建模,求得选址结果;在求解算法上,运用改进二进制蝙蝠算法进行求解,根据结果验证改进的算法更优.

This paper proposes a command generation approach based on the smooth interpolation without twist constraints and the input-output relation developed by the generalized model predictive static programming. Commands are efficiently generated to achieve the desired terminal condition at a specified final time in an interpolative manner featuring a noniterative nature. The effectiveness of this approach is demonstrated through three different simulation studies including a double integrator benchmark, a soft lunar landing problem, and a cluster missile guidance problem.

No AccessEngineering NotesProbabilistic Assessment of a Safety-Critical Backup Controller by Subset SimulationMengmeng Wang, Shuguang Zhang, Florian Holzapfel, David Löbl and Fabian HellmundtMengmeng WangBeihang University, 100191 Beijing, People’s Republic of China*Ph.D. Candidate, School of Transportation Science and Technology.Search for more papers by this author, Shuguang ZhangBeihang University, 100191 Beijing, People’s Republic of China†Professor, School of Transportation Science and Technology.Search for more papers by this author, Florian HolzapfelTechnical University of Munich, 85748 Garching, Germany‡Professor, Institute of Flight System Dynamics. Associate Fellow AIAA.Search for more papers by this author, David LöblTechnical University of Munich, 85748 Garching, Germany§Ph.D. Candidate, Institute for Flight System Dynamics.Search for more papers by this author and Fabian HellmundtTechnical University of Munich, 85748 Garching, GermanyDr.-Ing., Institute of Flight System Dynamics.Search for more papers by this authorPublished Online:2 Jan 2019https://doi.org/10.2514/1.G003901SectionsRead Now ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail About References [1] Federal Aviation Administration, “Part 25-Airworthiness Standards: Transport Category Airplanes,” Subchapter C, Title 14, e-CFR, FAA, Washington, D.C., April 2018. Google Scholar[2] European Aviation Safety Agency, “Certification Specifications and Acceptable Means of Compliance for Large Aeroplanes, CS-25, Amdt. 21,” EASA, Cologne, Germany, 2018. 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D., Leitão M. and Holzapfel F., “Performance and Robustness Metrics for Adaptive Flight Control-Available Approaches,” AIAA Guidance, Navigation, and Control (GNC) Conference, AIAA Paper 2013-5090, 2013. doi:https://doi.org/10.2514/6.2013-5090 LinkGoogle Scholar Previous article Next article FiguresReferencesRelatedDetailsCited byCoupled Subset Simulation and Moving Least-Squares Method for Reliability-Based Control OptimizationDalong Shi and Florian Holzapfel3 May 2021 | Journal of Guidance, Control, and Dynamics, Vol. 44, No. 8Enhancing Resilience of Airborne Wind Energy Systems Through Upset Condition AvoidanceSebastian Rapp and Roland Schmehl24 November 2020 | Journal of Guidance, Control, and Dynamics, Vol. 44, No. 2Efficient Verification and Validation of Performance-Based Safety Requirements using Subset SimulationChinmaya Mishra, Florian Schwaiger, Niclas M. Bähr, Franz Sax, Marc Andreas Kleser, Pranav Nagarajan and Florian Holzapfel4 January 2021 What's Popular Volume 42, Number 5May 2019 CrossmarkInformationCopyright © 2018 by Mengmeng Wang, Shuguang Zhang, Florian Holzapfel, David Löbl, and Fabian Hellmundt. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the eISSN 1533-3884 to initiate your request. See also AIAA Rights and Permissions www.aiaa.org/randp. TopicsAircraft Components and StructureAircraft ControlAircraft DesignAircraft Flight Control SystemAircraft InstrumentsAircraft Operations and TechnologyAircraft Stability and ControlAircraft SystemsAircraft Wing DesignAircraftsFlight Control SurfacesFlight Display SystemsFlight TrainingFlying QualitiesLongitudinal Static Stability KeywordsElevator DeflectionFlight Control SystemControl DerivativesLongitudinal ControlCumulative Distribution FunctionFlying WiresHandling QualitiesNonlinear DynamicsControl AlgorithmBoeing 747AcknowledgmentsThe research is supported by the National Laboratory for Aeronautics and Astronautics at Beihang University and the August-Wilhelm Scheer Visiting Professor Program at Technical University of Munich.PDF Received14 June 2018Accepted7 November 2018Published online2 January 2019

Software-defined Networking (SDN) is a representative next generation network architecture, which allows network administrators to programmatically initialize, control, change and manage network behavior dynamically via open interfaces. However, SDN brings new security problems, e.g., controller hijacking, black-hole, unauthorized data modification, etc. It is desirable to develop a unified platfom to enhance the security property and facilitate the security configuration and evaluation. In this paper, we propose OSCO (Open Security-enhanced Compatible OpenFlow) platform, a platform based on Raspberry Pi Single Board Computer (SBC) hardware and SDN network architecture, which supports highly configurable cryptographic algorithm modules, security protocols, flexible hardware extensions and virtualized SDN networks. Furthermore, we present an enhanced OpenFlow protocol to improve the security in SDN data plane. We implement and evaluate the prototype system and the experiment results show that our system conducted security functions with relatively low computational and networking performance overheads.

This paper addresses a three-dimensional wind estimation problem for fixed-wing aircraft based on the tracking model predictive static programming which was originally proposed for trajectory tracking control. Without relying on any airflow measurement, the wind velocity is estimated by considering the wind vector as a virtual control input. The wind vector is corrected in real time so that the model output tracks the measured kinematic velocity states in a command-tracking manner. The proposed method features a closed-form solution and a fast indication of wind variations. The effectiveness of the proposed method is illustrated by numerical simulations in the presence of measurement noises.

确保SDN流表更新的一致性,对保障网络配置更新过程的正确性与SDN的有效、安全运行,具有重要的意义.针对SDN配置更新所引起的数据包处理不一致问题,提出一种基于分类和时序的SDN流表更新一致性方案.通过设计交换机分类方案及优化更新顺序,实现了SDN流表更新的一致性和新、旧路径的数据并行传输,在保证方案良好通用性和隔离性的基础上,有效控制了更新时间和交换机存储空间的占用率,并降低了控制器的上传负载.

Software-defined networking (SDN) is a representative next generation network architecture, which allows network administrators to programmatically initialize, control, change, and manage network behavior dynamically via open interfaces. SDN is widely adopted in systems like 5G mobile networks and cyber-physical systems (CPS). However, SDN brings new security problems, e.g., controller hijacking, black-hole, and unauthorized data modification. Traditional firewall or IDS based solutions cannot fix these challenges. It is also undesirable to develop security mechanisms in such an ad hoc manner, which may cause security conflict during the deployment procedure. In this paper, we propose OSCO (Open Security-enhanced Compatible OpenFlow) platform, a unified, lightweight platform to enhance the security property and facilitate the security configuration and evaluation. The proposed platform supports highly configurable cryptographic algorithm modules, security protocols, flexible hardware extensions, and virtualized SDN networks. We prototyped our platform based on the Raspberry Pi Single Board Computer (SBC) hardware and presented a case study for switch port security enhancement. We systematically evaluated critical security modules, which include 4 hash functions, 8 stream/block ciphers, 4 public-key cryptosystems, and key exchange protocols. The experiment results show that our platform performs those security modules and SDN network functions with relatively low computational (extra 2.5% system overhead when performing AES-256 and SHA-256 functions) and networking performance overheads (73.7 Mb/s TCP and 81.2Mb/s UDP transmission speeds in 100Mb/s network settings).

Due to serious risks for network, security improvement has become an essential measure for next-generation network. To improve the security environment effectively, we propose a novel security service path (SSP) construction scheme based on reconfigurable mechanism in this paper. Initially, we present the concept of security service atomization and adaptiveness. Subsequently, considering different network security factors, a novel SSP selection method with corresponding model is established and performed to optimize the path. The results demonstrate that the proposed solution meets the security requirements and greatly improves the efficiency of network resources.

Software Defined Networking (SDN) is one type of the flow-rule-driven networks. In SDN, a centralized controller dictates the network behavior and configures network devices via flow rules. Therefore, the validity and consistency of flow rules are the critical for the security of operations in SDN, requiring a secure and efficient mechanism to manage and authenticate flow rules between the controller and network devices. In this paper, we aim to develop solutions to guarantee the validity of flow rules in SDN. We analyze the mechanisms that generate and manage flow rules in SDN, and present PERM-GUARD, a fine-grained permission management and authentication scheme for flow rules in SDN. PERM-GUARD employs a new permission authentication model and introduces an identity-based signature scheme for the controller to verify the validity of flow rules. We conduct theoretical analysis and simulation-based evaluation of PERM-GUARD. The results demonstrate that PERM-GUARD can efficiently identify and reject fake flow rules generated by unregistered applications. Meanwhile, it can also effectively filter out unauthorized flow rules created by valid applications, and trace their creator timely and accurately.

The microstructure and performance of MgO ceramics with different Al2O3 contents were investigated by X-ray diffractometer (XRD),scanning electron microscope (SEM),EDS analysis,electronic universal testing machine and Archimedes drainage method.The results show that addition of Al2O3 improved sinterability of MgO ceramics;During the sintering process,Al2O3 reacted with MgO to form MgAl2O4 ceramic phase around the MgO particles,which can make the particles combined closely and fill the pores,so as to reduce the porosity and enhance the density.The sample sintered at 1500 ℃ for 2 h had linear shrinkage ratio of 20.93％,volume density of 1.4995 g · cm-3,porosity of 12.41％ and the bending strength of 45.6 MPa,when the adding amount of Al2O3 was 20％.With the addition of Al2O3,the thermal shock resistance of MgO ceramics is improved,when the adding amount of Al2O3 was 10％,the thermal shock resistance of MgO ceramics is the best.

This paper proposes a fast real-time estimation algorithm which is inspired by the philosophy of the generalized model predictive static programming and solves the three-dimensional wind estimation problem in an optimal control manner. The wind estimation problem is transformed into a static optimization problem featuring a highly efficient solving framework. The proposed algorithm estimates the three-dimensional wind components without considering any hypothesis on the structure of the wind, and without relying on airspeed measurements either. The measurement noise and the model uncertainties are applied. Simulations demonstrate the rapidity and accuracy of the proposed method.

Software-Defined Networking（SDN） decouples the control plane and the data plane in network switches and routers, which enables the rapid innovation and optimization of routing and switching configurations. However,traditional routing mechanisms in SDN, based on the Dijkstra shortest path, do not take the capacity of nodes into account, which may lead to network congestion. Moreover, security resource utilization in SDN is inefficient and is not addressed by existing routing algorithms. In this paper, we propose Route Guardian, a reliable securityoriented SDN routing mechanism, which considers the capabilities of SDN switch nodes combined with a Network Security Virtualization framework. Our scheme employs the distributed network security devices effectively to ensure analysis of abnormal traffic and malicious node isolation. Furthermore, Route Guardian supports dynamic routing reconfiguration according to the latest network status. We prototyped Route Guardian and conducted theoretical analysis and performance evaluation. Our results demonstrate that this approach can effectively use the existing security devices and mechanisms in SDN.

软件定义网-(software defined networking,简称SDN)初步实现了网络控制面与数据面分离的思想,然而在提供高度开放性和可编程性的同时,网络自身也面临着诸多安全问题,从而限制了SDN在很多场景下的大规模部署和应用.首先对SDN的架构和安全模型进行分析;其次,从“SDN特有/非特有的典型安全问题”和“SDN各层/接口面临的安全威胁”两方面,对SDN中存在的典型安全威胁和安全问题进行分析和归纳;随后从6个方面对现有SDN安全问题的主要解决思路及其最新研究进展分别进行探讨,包括SDN安全控制器的开发、控制器可组合安全模块库的开发和部署、控制器DoS/DDoS攻击防御方法、流规则的合法性和一致性检测、北向接口的安全性和应用程序安全性;最后对SDN安全方面的标准化工作进行了简要分析,并对SDN安全方面未来的研究趋势进行了展望.

Software-defined networking (SDN) supports flexibly routing and switching by splitting the control plane and data plane in network devices. However, the security resource utilization now in SDN is inefficient, especially in the process of routing path construction. In this paper, we present a novel model for SDN controller to construct secure routing paths based on Network Security Virtualization (NSV) and the latest network status. Our new scheme considers various security devices' functionalities and the trust of different network devices in routing path establishment. We also introduce an identity-based authentication module to ensure the legitimacy of routing policies in SDN. We implement the prototype system, NSV-GUARD, and conduct theoretical analysis and performance evaluation. The results demonstrate that our approach can optimally utilize existing security devices and mechanisms in SDN. In addition, NSV-GUARD can efficiently verify malicious and fake routing policies generated by unregistered routing applications.

采用X射线衍射仪、扫描电镜、LFA 467激光导热测试仪及电子万能试验机研究了微量Zn对铸态AM60-2mass％ RE镁合金导热性能和力学性能的影响.结果表明:合金中添加的微量Zn主要固溶于基体中,未与合金中其他元素形成中间相;但Al4 RE和Al11RE3相数量显著增加,沿晶界成断续状态分布.Zn含量从0.2 mass％增加到0.8 mass％时,合金的导热系数从63.6 W·(m·K)-1降低至58.8 W·(m·K)-1;铸态合金的抗拉强度和维氏硬度分别从168 MPa和57 HV增加至185 MPa和62HV,冲击韧性和断后伸长率分别从20 J·cm-2和8.6％降低至15 J·cm-2和6.2％.

For today's commercial airliners, modern fly-by-wire systems provide excellent handling qualities and disturbance rejection capability, which significantly reduce pilot workload during manual flight, thus potentially increasing flight safety. However, in case of severe system failures or unexpected dynamics, many systems immediately degrade to direct mode, where the expected functions and protections degrade or even disappear. This paper assesses whether, with only pitch rate measurable, an emergency longitudinal controller built for a large transport aircraft featuring unstable pitch-up nonlinearities can provide acceptable handling qualities. A requirement-driven, sequential synthesis controller design process is developed, integrating quantitative feedback theory and L-1 piecewise constant output-feedback control theory. The quantitative feedback technique is used to generate a fixed-gain controller to avoid airspeed or dynamic pressure based gain scheduling and provide level 1 handling qualities without existence of the pitch-up nonlinearity. L-1 augmentations are further introduced to eliminate the performance degradation caused by the pitch-up nonlinearity. The fixed-gain controller and the L-1 controllers perform satisfactorily regarding performance and robust metrics within the entire envelope.