A hazard analysis via an improved timed colored petri net with time–space coupling safety constraint

Petri nets are graphical and mathematical tools that are applicable to many systems for modeling, simulation, and analysis. With the emergence of the concept of partitioning in time and space domains proposed in avionics application standard software interface(ARINC 653), it has become difficult to analyze time–space coupling hazards resulting from resource partitioning using classical or advanced Petri nets. In this paper, we propose a time–space coupling safety constraint and an improved timed colored Petri net with imposed time–space coupling safety constraints(TCCP-NET) to fill this requirement gap. Time–space coupling hazard analysis is conducted in three steps: specification modeling, simulation execution, and results analysis. A TCCP-NET is employed to model and analyze integrated modular avionics(IMA), a real-time, safety-critical system. The analysis results are used to verify whether there exist time–space coupling hazards at runtime. The method we propose demonstrates superior modeling of safety-critical real-time systems as it can specify resource allocations in both time and space domains. TCCP-NETs can effectively detect underlying time–space coupling hazards.     

Sociotechnical Systems Evolution and International Stability: 1885-2001

A number of evolutionary sociotechnical patterns associated with the intensification of warfare and movement of the international system into a domain far from equilibrium are discussed. Evolution is extended from the past 100 years to the end of the 20th century with the identification of several likely crises precipitatory to World War III. Systems theoretic interpretation of a number of evolutionary developments is made. The use of systems concepts and systems experts in the management of international stability is discussed further.     

Impact and the design of the human-machine interface

In this paper, we consider the concept of the impact of an action or human error. We begin from an informal definition of impact as: the effect that an action or sequence of actions has on the safe and successful operation of a system; and develop a quantitative measure of the impact of specified behaviours. It is important that human-machine interface designers should understand the relationship between operator actions and the hazards associated with a system. We demonstrate how impact can be assessed prior to, or in parallel with, the design of the human-machine interface, and show how impact assessments could be used to allow risk analysts to inform designers about the relationship between operator actions and system hazards. To illustrate our approach we present a simple case study,     

Landing system verification based on petri nets and a hybrid approach

One of the most important activities of control system design is its verification. Verification ensures that the controlled system will behave as expected under any circumstances it may operate. In this context, the purpose of this paper is to introduce a new method for the verification of aircraft control systems. The focus of this method is on aircraft systems that are characterized as hybrid, i.e., that merge continuous and discrete dynamics. The method proposed is divided into two main parts: the system modeling and the verification of behavioral properties. In the first part, Petri net, differential equation systems, and object oriented concepts are used concurrently in order to model complex hybrid systems. In the second part, the distributed nature of the model is explored in order to decompose a complex verification problem into series of simple local problems. Linear logic is used as a basis of a theorem-proving approach for the verification from the discrete-event point of view. The verification method has been applied to a number of case studies. Among them is the landing system of a military aircraft, which is described in this paper     

运用SSM探讨高校科研成果的产业化

软系统方法（ＳＳＭ）是一个学习系统，能帮助人们认识人类问题的复杂环境，为人们提供一种用系统的观点认识软问题的思想方法。运用软系统方法综合分析高校科研成果产业化所面临的形势及存在的问题，按照根定义建立概念模型，然后经过理想的概念模型与现实的比较，得出了一系列解决问题的方法与策略。对在新形势下如何促进高校科研成果产业化做了有益的探讨。     

竞争失效场合步进应力加速试验统计分析

竞争失效场合加速试验(AT)技术是加速试验由简单结构产品向复杂结构产品推广应用的基础.但目前的方法主要针对恒定应力加速试验.而对竞争失效场合步进应力加速试验缺乏相关研究.针对这一问题,对最一般形式(突发型失效和退化型失效并存)的竞争失效场合步进应力试验进行建模与分析.充分考虑了试验数据由于试验截尾和失效样本对应的失效模...     

发动机非包容性转子失效布置与防护设计

民用飞机发动机服役经验表明:发动机非包容性转子失效仍会发生。为将这种非包容性转子失效可能带来的危害降至最低,基于一种发动机翼吊式安装的民用飞机,结合咨询通告AC20-128A的要求以及民用飞机设计的工程经验,开展了飞机内部系统布置和结构防护设计研究。首先介绍了减小发动机非包容性转子失效危害的设计流程和分析模型,其次从民航局审查关注的角度,重点阐述了不可控制的着火、推力损失、飞机操纵的损失、对乘客和机组人员的保护和结构完整性等五个方面的设计思路和方法。研究结果表明:飞机设计时,通过采取将关键部件和系统移出碎片影响区、冗余设计、提供可接受的防护等预防措施来减小发动机非包容性转子失效对飞机的危害,对发动机非包容性转子失效的设计和适航验证具有指导意义。     

飞机腐蚀与防护

飞机腐蚀是每个航空公司都必须面对的问题。随着飞机服役时间的增加,有效地检查出飞机结构上存在的各种腐蚀,并进行去除,更是成为延长飞机使用寿命的关键。本文详细分析了飞机腐蚀的种类,根据腐蚀的特点及表现形式,介绍了相应的检查方法及去除方法。最后有针对性地提出了各种防护措施。     

2021年国外惯性技术发展与回顾

对2021年IEEE惯性传感器与系统会议、MEMS国际会议、圣彼得堡组合导航会议等惯 性技术相关会议文献,以及惯性技术领域相关机构披露的动态信息进行详细梳理。总结了光学陀 螺、微机电(MEMS)陀螺、半球谐振陀螺(HRG)、原子陀螺和加速度计等惯性仪表及惯性系统的发 展现状,并对惯性技术领域的发展动向进行了剖析与展望。     

转子爆破对飞机机体结构危害的风险量化方法研究

结合某型民用飞机转子爆破对机体结构危害的风险量化分析经验,通过对系统的处理方法进行类比,以概率统计为基础,将转子爆破对飞机机体的危害进行分级量化,形成了1套典型分析方法,可为其他型号飞机的相关设计工作提供借鉴。     

Future architecture of flight control systems

The development of fault tolerant embedded control systems such as flight control systems (FCS) are currently highly specialized and time-consuming. We introduce a conceptual architecture for the next decade control system where all control and logic are distributed to a number of computer nodes locally linked to actuators and connected via a communication network. In this way, we substantially reduce the life-cycle cost of embedded systems and attain scalable fault tolerance. All fault tolerance is based on redundancy. Our philosophy is to cover permanent faults with hardware replication and handle all error processing caused by both permanent and transient faults with software techniques. With intelligent nodes and use of inherent redundancy we introduce a robust and simple fault tolerant system that utilizes minimum hardware and has bandwidth requirements of less than 300 kbits/s, which can be met with an electrical bus. The study is based on an FCS for JAS 39 Gripen, a multi-role combat aircraft that is statically unstable at subsonic speed.     

Computational intelligence and soft computing for spaceapplications

Systems using computational intelligence and soft computing have been successfully developed for many industrial and space applications. These systems seek to emulate the type of reasoning that humans perform when solving complex tasks. The field of soft computing, as defined by Zadeh-the inventor of fuzzy logic-encompasses fuzzy logic as well as other methodologies such as neural networks, genetic algorithms, and uncertainty management. It is expected that soft-computing techniques will eventually become as common and prevalent as traditional methods of computer science. This paper presents an overview of applications of fuzzy logic and soft computing to space projects. The role of fuzzy systems that can learn from experience to improve their performance is discussed. We present a report on applications of these adaptive systems to NASA space projects such as the orbital operations of the Space Shuttle, which include attitude control and rendezvous/docking operations. We also provide insights on the future of computational intelligence and soft computing and of their vast potential in industrial applications     

Streamwise vortex generation by the rod

The technology development related to aerodynamics is leading to ever increasing loads of wings, airfoils and turbine and compressor blades. The increase in aerodynamic forces is often leading to flow separation and depreciation of the aerodynamic performance of flying objects or propulsion systems. Flow control methods are required to avoid these negative effects. In the recent two decades the flow control by means of air-jet vortex generators has been also intensively investigated. In this method a streamwise vortex is introduced by an oblique jet. The necessity to supply air by a pipe system may be considered a disadvantage. In order to eliminate this feature, it has been proposed to put out a rod instead of a jet. It has been shown that the application of a rod can introduce the same effect as a jet, as long as the streamwise vortex generation is concerned and appropriate dimensions are used. The present paper focuses on the influence of rod vortex generators on a flow pattern downstream. The results presented here concern experimental and numerical investigations and provide guidelines for the design of a new flow control method dedicated mainly to external flows.     

惯性加速度计电流电压转换误差研究

在以压频转换为核心的石英挠性加速度计的数据采集应用中,以何种方式实现电流电压转换并保证引入误差最小,尚未有明确的计算与论证。本文通过对几种可能出现的电流电压转换方式的误差进行分析和计算,从基础结构上明确了这几种转换方式的优劣,得到了最佳转换方案。     

Multiple hierarchy risk assessment with hybrid model for safety enhancing of unmanned subscale BWB demonstrator flight test

To explore the low-speed characteristics of the Blended-Wing-Body (BWB) configuration for future civil aircraft, a series of unmanned subscale demonstrators have been developed and tested by our research team. During this process, specific safety risks deriving from uncertain design features, system unreliability, and insufficient personnel experience caused continuous flight test mishaps and the risk mechanism was not clear. Local and trial-and-error learning driven safety improvements took few effects on mishap prevention, so our focus was turned to look for systematic safety strategies. This paper establishes a systems theory based hybrid model to integrate the physical system reliability analysis techniques with the system dynamics method for illustrating the multiple risk interactions of the demonstrator flight test involving organizational, human resource and technical system factors. Using the prior BB-5 demonstrator as a case, the hybrid model simulation represents its historical risk evolution process, which verifies the model rationality. Derived risk control strategies reduced the mishap rate of a new demonstrator called BB-6 Sprit. The paper also shows the extended hybrid model can be applied on safety management of unmanned aerial vehicles from the initial period of vehicle development.     

软交换承载网络组网模式分析与研究

针对软交换网络中信令流、媒体流和维护流等业务流的交互需求,结合SOFTX3000软交换设备、UMG8900通用媒体网关设备和UA5000用户接入设备相关单板的工作原理,分析了采用二层组网模式的承载网络存在的弊端,提出了基于OSPF(Open Shortest Path First,开放式最短路径优先)协议的三层路由组网模式,并在某电话局软交换网络中得到应用。经分析,采用三层路由组网模式相比于二层组网模式具有更高的安全性和可靠性。     

Successful Large-Scale Use of CMOS Devices on Spacecraft Traveling Through Intense Radiation Belts

This paper describes the environmental models of the radiation belts and computational techniques which have been developed for predicting the radiation hazards for spacecraft These data and techniques are then applied to the Atmosphere Explorer 51 spacecraft to explain its successful survival for more than 18 months in a severe environment In particular, the results of the analysis are used to explain the performance of sonm 2400 CMOS devices, and consequently, they demonstrate the reliability of this device technology gy in spacecraft systems.     

半硬式临近空间飞艇结构设计技术研究

结合某型号工程实例,简述了半硬式临近空间飞艇中各种承载部件的结构布局形式,以及结构之间的连接形式;以纺锤形临近空间飞艇为例,利用经验公式对软式、半硬式艇体分系统的质量进行评估;应用MSC.PATRAN/NASTRAN有限元分析软件分别建立软式、半硬式两种形式的结构有限元模型,并进行强度求解。结果表明：在相同边界约束、工况条件下,与软式飞艇相比,半硬式飞艇不仅结构强度高,有着很高的结构承载效率,而且有利于结构重心的布置,更符合结构设计规范要求。     

航空发动机非包容转子失效危险识别

为分析多重非包容转子碎片对飞机造成的危害,提出一种基于飞机整机功能危险分析(FHA)结果、应用故障树分析(FTA)的非包容转子碎片失效危险识别方法。该方法能够识别多个系统同时失效导致的组合危险,进而为非包容转子失效飞机设计改进提供更详实、可信的依据。最后通过实例分析表明了方法的有效性。     

Aircraft health management network: A user interface

Network management is one of the most discussed topics in the networking fraternity. The efficiency of the network management suit is measured by the number of parameters/components handled by the application while making decisions. In the case of internet-enabled aircrafts, along with network security, even aircraft safety needs to be considered as a factor while designing the Network Management suit. This requires the Network Management suit to monitor/analyze the aircraft-related data (avionics data, physical security parameters, etc.) while determining the proper functioning of the overall system. Herein, these authors present a framework for Network Management suit that, along with network health, monitors inputs from avionics, video surveillance system, weather monitoring system, and manual pilot alarms, and based on the situation, reconfigures the on-board networking devices to stream appropriate flight-critical data to the ground station. The proposed framework attempts to provide a comprehensive user interface for the flight health monitoring crew with all relevant data.