An innovative approach for integrated airline network and aircraft family optimization

The determination of optimal aerial transport networks and their associated flight frequencies is crucial for the strategic planning of airlines,as well as for carrying out market research,to establish target markets,and for aircraft and crew rostering.In addition,optimum airplane types for the selected networks are crucial to improve revenue and to provide reduced operating costs.The present study proposes an innovative approach to determine the optimal aerial transport network simultaneously with the determination of the optimum fleet for that network,composed of three types of airplanes (network and vehicle integrated design).The network profit is maximized.The passenger's demands between the airports are determined via a gravitational model.An embedded linear programming solution is responsible for obtaining potential optimal network configurations.The optimum fleet combination is determined from a database of candidate aircraft designs via genetic algorithm.A truly realistic airplane representation is made possible thanks to accurate surrogate models for engine and aerodynamics is adopted.An accurate engine deck encompassing a compression map and an innovative engine weight calculation besides an aerodynamical artificial neural network module enable a high degree of accuracy for the mission analysis.The proposed methodology is applied to obtain the optimum network comprised of twenty main Brazilian airports and corresponding fleet.     

Individual aircraft life monitoring: An engineering approach for fatigue damage evaluation

Individual aircraft life monitoring is required to ensure safety and economy of aircraft structure, and fatigue damage evaluation based on collected operational data of aircraft is an integral part of it. To improve the accuracy and facilitate the application, this paper proposes an engineering approach to evaluate fatigue damage and predict fatigue life for critical structures in fatigue monitoring. In this approach, traditional nominal stress method is applied to back calculate the S-N curve parameters of the realistic structure details based on full-scale fatigue test data. Then the S-N curve and Miner’s rule are adopted in damage estimation and fatigue life analysis for critical locations under individual load spectra. The relationship between relative small crack length and fatigue life can also be predicted with this approach. Specimens of 7B04-T74 aluminum alloy and TA15M titanium alloy are fatigue tested under two types of load spectra, and there is a good agreement between the experimental results and analysis results. Furthermore, the issue concerning scatter factor in individual aircraft damage estimation is also discussed.     

基于多准则决策的作战飞机顶层方案优选

提出了综合应用灰色关联投影法、加权求和法、加权求积法和基于理想点决策法来实现对无人作战飞机顶层方案的优选,并着重介绍了多准则决策方法及实施过程。该方法采用不同的公度化方法处理相应的评价指标,对多目标、多层次指标体系进行赋权,利用权重将评价指标联系在一起,并将四种准则决策法进行综合,依据决策者的偏好,最终实现顶层方案的优选。最后,通过制空无人作战飞机顶层方案优选的例子,证实了所提方法是可行且有效的。     

A unified approach to the design of decentralized detection systems

A unified approach to the design of decentralized detection networks with arbitrary topologies is proposed and analyzed. In this approach, a decentralized detection system of arbitrary topology is represented by a communication matrix that specifies the interconnection structure of the detection network. This matrix is used to derive the general decision rule using the person-by-person-optimal (PBPO) solution methodology. It is shown that the PBPO decision rule is a likelihood ratio test for statistically independent observations. The threshold of the test is shown to be a function of the decision input vector of the detector under consideration. This unified approach is used to obtain the PBPO decision rules of decentralized detection systems with various topologies. Various results in the literature are verified. In addition, the PBPO decision rules for a decentralized detection system with peer communication are presented. Numerical examples are presented for illustration     

Minimization of aircraft engineering enterprise losses

A technique for the econometric analysis of aircraft engineering enterprise activity results using the annual and quarterly reports is presented. A reliable nonlinear form of the objective function of losses optimized by the gradient descent method is obtained.     

A cost effective critical space systems design approach

NASA-ISC requires avionics platforms capable of serving a wide range of applications in a cost-effective manner. In part, making the avionics platform cost effective means adhering to open standards and supporting the integration of COTS products with custom products. Inherently, operation in space requires low power, mass, and volume while retaining high performance, reconfigurability, scalability, and upgradability. The Universal Mini-Controller (UMC) project is based on a modified PC/104-Plus architecture while maintaining full compatibility with standard COTS PC/104 products. The architecture consists of a library of stackable building block modules, which can be mixed and matched to meet a specific application. A set of NASA developed core building blocks, (e.g. processor card, analog input/output card, high level analog card, and a Mil-Std-1553 card) were constructed to meet critical functions and unique interfaces     

An algorithm for computer-aided design calculation of aircraft stability and controllability parameters

An algorithm is proposed for computer-aided calculation of required values of aircraft controlling moments and aerodynamic moment coefficients for stable fulfillment of flight trajectories specified by design flight performance.     

An optimal method of posture adjustment in aircraft fuselage joining assembly with engineering constraints

Posture of an aircraft fuselage can be evaluated based on the coordinate values of measure points fixed on the aircraft fuselage in aircraft final assembly. Posture adjustment is carried out by rotation and translation of the aircraft fuselage to make sure that the actual coordinate values of the measure points are coincided with the theoretical ones read from the computer aided design(CAD) model. The point registration method of posture adjustment without considering engineering constraints may cause out-of-tolerance for some engineering constraints. Hence, engineering constraints such as plane symmetry of two points, as well as coplanar and collinear of the multipoint should be considered in the new optimal method of posture adjustment in aircraft fuselage joining assembly. Based on the point registration model, a multi-objective optimization model of posture adjustment considering engineering constraints including collinear, coplanar, and symmetry constraints is established and represented by a uniform vector function. The weights of constraint conditions can be set freely in the optimization model to reflect the importance of the corresponding constraints in aircraft fuselage joining assembly. The rotation and translation parameters of posture adjustment are obtained by the proposed multi-objective optimization algorithm based on the Gauss-Newton method. Results of an example of aircraft fuselage joining assembly show that constraint errors of posture adjustment obtained by the multi-objective optimization model are not out of tolerance for design constraint errors and satisfy the requirement of aircraft fuselage joining assembly.     

Hybrid partition-and network-level scheduling design for distributed integrated modular avionics systems

Distributed Integrated Modular Avionics(DIMA) develops from Integrated Modular Avionics(IMA) and realizes distributed integration of multiple sub-function areas. Timetriggered network provides effective support for time synchronization and information coordination in DIMA systems. However, inconsistency between processing resources and communication network destroys the time determinism benefiting from partitions and time-triggered mechanism.To ensure such time determinism and achieve guaranteed real-time performance, system design should collectively provide a global communication scheme for messages in network domain and a corresponding execution scheme for partitions in processing domain. This paper firstly establishes a general DIMA model which coordinates partitioned processing and time-triggered communication, and then proposes a hybrid scheduling algorithm using Mixed Integer Programming to produce feasible system schemes. Furthermore, incrementally integrating new functions causes upgrades or reconfigurations of DIMA systems and will generate integration cost. To control such cost, this paper further develops an optimization algorithm based on Maximum Satisfiability Problem and guarantees that the scheduling design for upgraded DIMA systems inherit their original schemes as much as possible. Finally, two typical cases, including a simple fully connected DIMA system case and an industrial DIMA system case, are constructed to illustrate our DIMA model and validate the effectiveness of our hybrid scheduling algorithms.     

Quasi-three-dimensional high-lift wing design approach considering three-dimensional effects of slipstream for distributed electric propulsion aircraft

The efficient utilization of propeller slipstream energy is important for improving the ultra-short takeoff and landing capability of Distributed Electric Propulsion(DEP) aircraft. This paper presents a quasi-three-dimensional(2.5D) high-lift wing design approach considering the three-dimensional(3D) effects of slipstream for DEP aircraft, aiming at maximizing the comprehensive lift enhancement benefit of the airframe-propulsion coupling unit. A high-precision and efficient momentum source method is adopted to simulate the slipstream effects, and the distributed propellers are replaced by a rectangular actuator disk to reduce the difficulty of grid generation and improve the grid quality. A detailed comparison of the 2.5D and 3D configurations based on the X-57 Mod Ⅳ is performed in terms of flow characteristics and computational cost to demonstrate the rationality of the above design approach. The optimization results of the high-lift wing of the X-57 Mod Ⅳ show that the aerodynamic performance of the landing configuration is significantly improved, for instance, the lift coefficient increases by 0.094 at the angle of attack of 7°,and 0.097 at the angle of attack of 14°. This novel approach achieves efficient and effective design of high-lift wings under the influence of distributed slipstream, which has the potential to improve the design level of DEP aircraft.     

民用飞机吊挂应急断离设计研究

应急断离设计是民用飞机吊挂设计的关键技术之一,从收集到的相关机型应急着陆事故论述吊挂应急断离设计的结构设计要求,分析波音公司和麦道公司的典型机型吊挂设计方案,提出了我国大型民用飞机吊挂应急断离设计方案的建议。     

50 years of transonic aircraft design

This article traces the evolution of long range jet transport aircraft over the 50 years since Kuechemann founded the journal Progress in Aerospace Sciences. The article is particularly focused on transonic aerodynamics. During Kuechemann's life time a good qualitative understanding had been achieved of transonic flow and swept wing design, but transonic flow remained intractable to quantitative prediction. During the last 50 years this situation has been completely transformed by the introduction of sophisticated numerical algorithms and an astonishing increase in the available computational power, with the consequence that aerodynamic design is now carried out largely by computer simulation. Moreover developments in aerodynamic shape optimization based on control theory enable a competitive swept wing to be designed in just two simulations, as illustrated in the article. While the external appearance of long range jet aircraft has not changed much, advances in information technology have actually transformed the entire design and manufacturing process through parallel advances in computer aided design (CAD), computational structural mechanics (CSM) and multidisciplinary optimization (MDO). They have also transformed aircraft operations through the adoption of digital fly-by-wire and advanced navigational techniques.     

Nanotechnology's impact on aircraft design and maintenance

Unique research efforts relating to the development of nanoscale devices to replace standard integrated circuits, and eventually entire electronic systems. Standard integrated circuits (IC) have limitations or restrictions in size, speed, reliability, complexity and finding suitable replacements for discontinued items. Nanoscale device development and understanding has dramatically grown. One of the key properties of quantum physics that quantum computers rely on is the ability of certain atoms or nuclei to work together as quantum bits. These computing devices are a fraction of the size of typical ICs (nanoscale). Nanoscale devices developed using quantum physics principles have unlimited potential to revolutionize the methods and design of fabricated printed circuit cards and complete systems. They can replace an entire PC board or the set of PC boards that comprise a Line Replaceable Unit (LRU). This would be a good and practical jumping-off point to going directly to the complete device, system, or function level. This might include a nanoscale computer (general purpose or flight control), transmitter, GPS receiver, position and/or attitude sensors in either a stand-alone configuration, or combined within conventional devices (e.g., a nanoscale communications suite (xmtr/rcvr, etc.)) encapsulated within the Plexiglas canopy or the control yoke of an F16 rather than behind the instrument panel or maybe the whole comm suite into the pilot's helmet.     

A statistical hypothesis testing approach to the determination ofsupportable aircraft separation standards

This paper deals with the setting of a statistical hypothesis testing approach to the determination of aircraft separation standards that can be supported within a given Flight Information Region. Given a minimal safety distance to be maintained between two aircraft, we derive a criterion that must be obeyed by their radar plots in order to meet the required separation at a known level of confidence. Conversely, given that a minimal safety distance is maintained between two radar plots, one can find the actual separation that can be guaranteed between both aircraft. The results described here can help to implement automated conflict alert and minimum safe altitude warning facilities     

乘波飞行器一体化构型设计

为提高高超声速飞行器设计的水平,提出一种结合优化设计和灵敏度分析的新设计策略,并将其应用于高超声速乘波飞行器的二维一体化构型的设计.结合实验设计方法、响应面技术和遗传算法构建了一套改进的优化方法,结合设计参数取值域、正交设计和方差分析发展了一种灵敏度分析方法.在优化设计过程中,通过参数化建模、网格自动生成和CFD求解,应用改进的优化方法对飞行器进行了多点多目标设计,得到了Pareto最优前沿面和优化推荐构型.针对推荐构型,应用灵敏度分析方法进行了非设计状态的性能分析,并基于灵敏度分析结果对推荐构型进行了修形设计.     

Expert systems in engineering

An overview of expert systems development and some engineering applications are presented. The characteristics of expert systems are first described. Three applications of expert systems, in factory scheduling, maintenance, and electronic testing, are briefly examined. Their advantages and disadvantages are discussed     

Frequency domain approach to guidance system design

The frequency domain approach to guidance system design is presented. The model of the guidance control system reflects the most important characteristics of the flight control system that combines airframe and autopilot dynamics (damping, natural frequency, time constant, and airframe zero frequency). The analytical expressions for frequency response and related expressions for missile system performance are given. The analytical results obtained can be utilized for missile system design.     

An approach to forming the design performance of the attitude control system for small spacecraft

The elements for various types of attitude control systems used in a number of small spacecraft are considered. An approach for assessment of such system effectiveness based on design requirements for spacecraft purpose and restriction in accuracy, mass and energy is proposed.     

浅析飞机维修计划和机务维修中的人为因素

本文从飞机维修计划和机务维修两方面对其中涉及的人为因素以及其所导致的不安全隐患进行了分析。通过从工作者自身以及沟通和管理等多个方面因素进行论证,并提出了相应的改进建议。     

一种空中交通图象特征匹配方法

提出了一种确定飞机类型的新方法。通过 机外型和结构特征,利用空间投影理论建立了飞机投影图形与飞机姿态角之间的关系。通过该关系方程,有效地识别了飞机姿态角。利用已有的飞机型的投影图特征与实际飞机飞行图像特征之间的误差,根据最小方差进行了模型匹配。利用ＣＣＤ系统图像仿真结果表明,所提出的方法是有效的。