Potential defense applications of expert systems

The authors provide an overview of expert systems and how they may effect the development of future defense applications. Military uses of computers are outlined, and expert-systems fundamentals are described. Artificial research and development efforts by the military are examined, and potential military applications are discussed. Expert systems efforts at NASA, by the US Air Force, and for the Strategic Defence Initiative are considered     

磁浮飞行风洞试验技术及应用需求分析

随着高速、超高速轨道交通的快速发展,需要发展新型的风洞设备,实现风洞性能和试验能力的突破。磁浮飞行风洞是利用真空管道列车概念结合动模型试验技术提出的一种新概念风洞设备,可以构建出更加接近真实状态的测试环境。本文从磁浮飞行风洞基本概念、国内外研究现状及发展趋势、试验技术、应用需求等几个方面开展论述。首先论述了国内外传统风洞和动模型设备的现状及发展趋势,指出了发展磁浮飞行风洞的必要性;其次,重点对磁浮飞行风洞需要发展的试验技术进行了分析;最后,对磁浮飞行风洞在超高速轨道交通及其他领域的应用需求进行了展望。     

A critique of reliability prediction techniques for avionics applications

Avionics (aeronautics and aerospace) industries must rely on components and systems of demonstrated high reliability. For this, handbook-based methods have been traditionally used to design for reliability, develop test plans, and define maintenance requirements and sustainment logistics. However, these methods have been criticized as flawed and leading to inaccurate and misleading results. In its recent report on enhancing defense system reliability, the U.S. National Academy of Sciences has recently discredited these methods, judging the Military Handbook (MIL-HDBK-217) and its progeny as invalid and inaccurate. This paper discusses the issues that arise with the use of handbook-based methods in commercial and military avionics applications. Alternative approaches to reliability design (and its demonstration) are also discussed, including similarity analysis, testing, physics-of-failure, and data analytics for prognostics and systems health management.     

New fire/smoke detection and fire extinguishing systems for aircraft applications

This paper gives an overview on the European Commission funded FIREDETEX Research Project. The project focuses on two aspects of aircraft fire protection: fire detection and fire suppression. New physical and chemical ways of detecting fire at an early stage will be investigated including detection in non-protected areas such as electronic bays. In the frame of halon replacement research the project will investigate the capabilities of an combined water mist/nitrogen suppression system. The project consortium consists of a partnership of 12 companies. Universities and Research Establishments from 5 European countries.     

Decoding techniques in state estimation for dynamic systems withpast histories

States of dynamic models with a higher order memory are estimated using both a stack sequential decoding algorithm and the Viterbi decoding algorithm (VDA), without higher dimensional dynamic system representation. This results in memory reduction for state estimate implementation. It is found that state estimation with a stack sequential decoding algorithm is faster and more practical than the state estimation with the Viterbi decoding algorithm, even though the estimates obtained by the Viterbi decoding algorithm are superior     

Cooling and lubrication techniques in grinding: A state-of-the-art review,applications, and sustainability assessment

Grinding technology is an essential manufacturing operation, in particular, when a component with a superfinishing and an ultra-resolution is yearned. Meeting the required strict quality checklist with maintaining a high level of productivity and sustainability is a substantive issue. The recent paper outlines the lubrication and cooling technologies and mediums that are used for grinding. Furthermore, it provides a basis for a critical assessment of the different lubrication/cooling techniques ...     

High-performance front-end converter for avionics applications [aircraft power systems]

The distributed power systems of future commercial aircraft will adopt variable frequency generation (360 to 800 Hz). Front-end converters in the system will be required to have a high efficiency and a low total harmonic distortion (THD) of the input current. This paper explains the design of a zero-voltage-switching (ZVS) active-clamped isolated low-harmonic SEPIC rectifier for such applications. Utilization of the transformer leakage inductance for ZVS and a single-layer transformer design contribute to a high efficiency. An accurate averaged switch model has been developed, which shows that the control-to-input-current transfer function of this converter does not exhibit resonances observed in the conventional SEPIC. As a result, for closed-loop operation using average current control, damping of the coupling capacitor is not required. Operating at a switching frequency of 200 kHz, an experimental 100 W, 28 V output rectifier achieves a THD of 3-4% and efficiency exceeding 90% over the entire line frequency range.     

Control techniques of tilt rotor unmanned aerial vehicle systems:A review

The tilt rotor unmanned aerial vehicle (TRUAV) exhibits special application value due to its unique rotor structure. However, varying dynamics and aerodynamic interference caused by tiltable rotors are great technical challenges and key issues for TRUAV's high-powered flight con-trols, which have attracted the attention of many researchers. This paper outlines the concept of TRUAV and some typical TRUAV platforms while focusing on control techniques. TRUAV struc-tural features, dynamics modeling, and flight control methods are discussed, and major challenges and corresponding developmental tendencies associated with TRUAV flight control are summa-rized.     

一种基于数值计算的轴流压气机旋转失速稳定性模型——之二:简化模型及应用

提出了一个基于直接数值计算结果基础上的旋转失速线性稳定性模型,描述了如何从基本的Navier-Stokes方程出发,把轴流压气机流动稳定性问题转化为一个特征值问题的基本理论框架,对压气机不稳定边界的判断通过计算和检验特征值的方式来实现,给出了有限差分法和基于Gauss-Lobatto节点的谱配置方法两种数值离散的方式,并分析了这两种离散方式的收敛特性.     

An IPC-based Prolog design pattern for integrating backward chaining inference into applications or embedded systems

Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, such as data acquisition and task scheduling, which are also crucial. To make the best use of the advantages and bypass the disadvantages, it is attractive to integrate Prolog with programs developed by other languages. In this paper, an IPC-based method is used to integrate backward chaining inference implemented by Prolog into applications or embedded systems. A Prolog design pattern is derived from the method for reuse, whose principle and definition are provided in detail. Additionally, the design pattern is applied to a target system, which is free software, to verify its feasibility. The detailed implementation of the application is given to clarify the design pattern. The design pattern can be further applied to wide range applications and embedded systems and the method described in this paper can also be adopted for other logic programming languages.     

Aerospace and military battery applications

This paper gives a review of the papers presented at the IEEE 17th Annual Battery Conference on Applications and Advances, Long Beach, CA, USA, 2002. The topics covered are: Li batteries for satellites, capacity fade of Li-ion cells cycled at different temperatures, Ni-H/sub 2/ battery lifetime, batteries for Mars-exploring vehicles, Li-ion cell performance enhancement at low temperatures, navy service batteries, and US Army man portable applications and mobile power challenges.     

Neural networks: implementations and applications

Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas     

Electromagnetic riveting technique and its applications

With the increasing applications of novel materials and structures in new-generation aircraft, conventional joining techniques in aircraft component assembly are greatly challenged. To meet those challenges, the electromagnetic riveting (EMR) technique was developed as an advanced joining tool, which exhibits obvious advantages in the assembly of new-generation aircraft. In this paper, the riveting principle of EMR was analyzed, and its development history and status were presented in detail. Then, equipment features of three typical EMR systems were given. Moreover, three important applications of EMR were covered, i.e., composite structure riveting, titanium rivet and large-size aluminum rivet riveting, and interference fit bolt installation. Specially, a novel strengthening method for mechanical linking holes based on EMR was also presented, which can significantly improve the fatigue behaviors of mechanical joints. Finally, open questions in the EMR field were discussed, and some recommendations for future work were also made. This paper can be useful for optimizing the joint designs of aircraft components and improving the level of aircraft maintenance.     

数字孪生及其在航空航天中的应用

数字孪生已引起国内外的广泛重视,可看作是连接物理世界和数字世界的纽带。其通过建立物理系统的数字模型、实时监测系统状态并驱动模型动态更新实现系统行为更准确的描述与预报,从而在线优化决策与反馈控制。本文分析表明数字孪生体相比一般的模拟模型,具有集中性、动态性和完整性的突出特点。数字孪生的发展需要复杂系统建模、传感与监测、大数据、动态数据驱动分析与决策和数字孪生软件平台技术的支撑。在航空航天领域,数字孪生可应用于飞行器的设计研发、制造装配和运行维护。重点讨论了应用机身数字孪生进行寿命预测与维护决策的案例,相比于周期性维护,具有检修次数更少、维护成本更低的优势。最后,给出了数字孪生在空间站、可重复使用飞船的地面伴飞系统中的初步应用框架。     

高速磨削技术的发展趋势及其相关技术

回顾了国内外高速磨削技术的发展过程,从高速磨削机理,高速磨削速度及其高速磨削相关技术等方面介绍国外的发展水平和先进成果,预测了今后国外高速磨削研究的发展趋势,并从高速度磨床的一些技术特征和参数,以及人们对高速磨削的认识等方面分析和评价了我国在推广和应用高速磨削中尚存的差距,可为进一步深入研究提供参考.     

Space-borne technology and inversion techniques for radar

This presents recent progress of the state-of-the-art of space-borne radar technology in case of either earth-orbiting or planetary-orbiting satellites and space probes, respectively. In addition to that, recent progress is also discussed concerning specific inversion techniques to evaluate radar measurements; i.e., the art of deriving the relevant physical quantities to be determined such as terrain and depth profiles for planetary surface and/or subsurface structures ((3D)-profiles) from radar data measured depending on signal frequency, aspect angle, polarization, etc., as a function of time.     

航空经济学及面向价值的飞机设计理论与实践

全球化的市场竞争是商用飞机产业的重要特征之一,对安全性、舒适性、经济性和环保性指标的不断追求推动着技术的不断进步及产业链的全球化发展。在飞机设计中,对经济性的考虑在航空技术和型号发展中的作用越来越突出,也是中国航空产业发展面临的重大挑战因素之一。在新技术研发决策及其在型号中的应用中,经济性考虑始终是决策的关键因素,本文综述航了空经济学的研究范畴和主要分析方法,及其对飞机概念设计、结构设计和系统选择等主要决策的影响,面向价值的设计理论和方法在飞机设计中的实践。希望本文的发表可以促进航空经济学的发展,相关方法可以在型号设计的最优综合评价中发挥作用,实现涵盖时间成本在内的综合评价指标最优的方案。可以预期,航空经济学的发展有助于提升中国航空制造业在竞争越来越激烈的全球航空产业链中的竞争力。