Safe airport operation based on innovative magnetic detector system

A novel magnetic sensing technology that forms the basis of an innovative system to monitor ground vehicle movements at airports is presented. The operating principle of this system is the detection of interaction of aircraft or ground vehicles with the earth?s magnetic field using sensitive magnetic field detectors. After development and laboratory testing of the detectors, test sites have been set up at three European airports. Potential applications of the detectors were designed and demonstrated. Tests have shown that the system can be applied for ground movement surveillance. The approach can be used as a complementary surveillance system for existing and future advanced surface movement guidance and control systems (A-SMGCS) at large airports or as a cost-effective stand-alone solution for monitoring critical areas at medium and small airports. Furthermore, this system can be applied as well in road traffic and car park occupancy monitoring. Unaffected by weather conditions, interference and shadowing effects, the system provides reliable vehicle position, velocity and direction information without requiring any equipment in aircraft or ground vehicles and thus it increases airport operational safety.     

Flight Test Engineering—An Integrated Design/Laboratory Course

Recognizing the need for more design opportunities as well as practical field experience in the undergraduate curriculum, the Department of Aerospace Engineering, Mechanics & Engineering Science at the University of Florida has introduced a course entitled “Flight Test Engineering.” Students are organized into teams which conduct a series of four flight test experiments including one involving an original design project. The course promotes interdisciplinary interaction in our curriculum and is supported by a variety of other courses in our department by contributions of assistance in data analysis, equipment calibration, wind-tunnel testing of equipment mounts, software development, and systems integration. As part of their original design project, students generate written technical documents and drawings and present oral reports to the Federal Aviation Administration to receive approval for installation of their equipment in the aircraft.     

The use of Functional Resonance Analysis Method (FRAM) in a mid-air collision to understand some characteristics of the air traffic management system resilience

The Functional Resonance Analysis Model (FRAM) defines a systemic framework to model complex systems for accident analysis purposes. We use FRAM in the mid-air collision between flight GLO1907, a commercial aircraft Boeing 737-800, and flight N600XL, an executive jet EMBRAER E-145, to investigate key resilience characteristics of the Air Traffic Management System (ATM). This ATM system related accident occurred at 16:56 Brazilian time on September 29, 2006 in the Amazonian sky. FRAM analysis of flight monitoring functions showed system constraints (equipment, training, time, and supervision) that produce variability in system behavior, creating demand resources mismatches in an attempt to perceive and control the developing situation. This variability also included control and coordination breakdowns and automation surprises (TCAS functioning). The analysis showed that under normal variability conditions (without catastrophic failures) the ATM system (pilots, controllers, supervisors, and equipment) was not able to close the control loops of the flight monitoring functions using feedback or feedforward strategies to achieve an adequate control of an aircraft flying in the controlled air space. Our findings shed some light on the resilience of Brazilian ATM system operation and indicated that there is a need of a deeper understanding on how the system is actually functioning.     

Rigorous uncertainty quantification without integral testing

We describe a rigorous approach for certifying the safe operation of complex systems that bypasses the need for integral testing. We specifically consider systems that have a modular structure. These systems are composed of subsystems, or components, that interact through unidirectional interfaces. We show that, for systems that have the structure of an acyclic graph, it is possible to obtain rigorous upper bounds on the probability of failure of the entire system from an uncertainty analysis of the individual components and their interfaces and without the need for integral testing. Certification is then achieved if the probability of failure upper bound is below an acceptable failure tolerance. We demonstrate the approach by means of an example concerned with the performance of a fractal electric circuit.     

Ice detection and classification on an aircraft wing with ultrasonic shear horizontal guided waves

Ice accumulation on airfoils has been identified as a primary cause of many accidents in commercial and military aircraft. To improve aviation safety as well as reduce cost and environmental threats related to aircraft icing, sensitive, reliable, and aerodynamically compatible ice detection techniques are in great demand. Ultrasonic guided-wave-based techniques have been proved reliable for "go" and "no go" types of ice detection in some systems including the HALO system, in which the second author of this paper is a primary contributor. In this paper, we propose a new model that takes the ice layer into guided-wave modeling. Using this model, the thickness and type of ice formation can be determined from guided-wave signals. Five experimental schemes are also proposed in this paper based on some unique features identified from the guided- wave dispersion curves. A sample experiment is also presented in this paper, where a 1 mm thick glaze ice on a 2 mm aluminum plate is clearly detected. Quantitative match of the experiment data to theoretical prediction serves as a strong support for future implementation of other testing schemes proposed in this paper.     

Examining improved experimental designs for wind tunnel testing using Monte Carlo sampling methods

Wind tunnels are used in the design and testing of a wide variety of systems and products. Wind tunnel test campaigns involve a large number of experimental data points, can take a long time to accomplish, and can consume tremendous resources. Design of Experiments is a systematic, statistically based approach to experimental design and analysis that has the potential to improve the efficiency and effectiveness of wind tunnel testing. In Defense Acquisition, wind tunnel testing of aircraft systems may require years of effort to fully characterize the system of interest. We employ data from a fairly large legacy wind tunnel test campaign and compare that data's corresponding response surface to the response surfaces derived from data generated using smaller, statistically motivated experimental design strategies. The comparison is accomplished using a Monte Carlo sampling methodology coupled with a statistical comparison of the system's estimated response surfaces. Initial results suggest a tremendous opportunity to reduce wind tunnel test efforts without losing test information. Published in 2010 by John Wiley & Sons, Ltd.     

基于PC/104的武装直升机观瞄装置检测系统设计和实现

观瞄装置是武装直升机实现武器精确瞄准和准确命中的关键设备,在分析其工作原理和检测需求的基础上,设计了以PC/104嵌入式系统为控制核心的检测系统;通过ARINC429总线和RS422主从式通信向观瞄装置下发控制命令,接收观瞄装置回复的自检、状态、指示和参数等数据;采用模块化设计方法开发了应用软件,应用多线程技术并以查询方式实现了数据接收的实时性,采用限时接收和计算校验和的方法进行数据通信的差错控制;检测系统集数据通信、实时数据处理、结果显示于一体,实现了对检测任务的调度和控制.     

New digital signal-Processing approach for transmitter measurements in third generation Telecommunications systems

The rapid growth of third generation (3G) telecommunications systems has created the need for getting new test equipment as well as getting measurement techniques up and running in a very short time. Trying to satisfy this exigency, a new measurement method for testing 3G transmitters is proposed here. Thanks to the use of time-frequency distributions, the method provides a unified approach for carrying out, automatically and in a very straightforward manner, most measurements needed to fulfill the aforementioned task. After a brief outline of 3G technology basics, some details concerning transmitter tests are given. The fundamental steps of the proposed method are then described with references to a clarifying example, also highlighting advantages with respect to other measurement solutions. At the end, the performance of the method is assessed by means of several experiments on both simulated and emulated signals.     

Development of a Bonded Repair for the F-16 FS479 Bulkhead Vertical Tail Attach Bosses

A bonded repair has been developed to repair cracked FS479 bulkheads on the F-16 aircraft. The cracking occurs at the vertical tail to aft fuselage interface in a sharp fillet between the vertical tail attach boss and the top flange of the bulkhead. The repair approach entails machining off the attach bosses along with any existing cracks, and bonding on a replacement 'saddle' with an optimized contour that eliminates the stress concentration caused by the fillet. As a final step the saddle is reinforced with boron doublers to optimize the load transfer. This repair is a cost effective alternative to bulkhead replacement because it can be applied in the field and does not require the removal of the bulkhead from the aircraft. To date, the repair has successfully completed proof of concept static testing over a temperature range of – 65F to 200F and durability testing at room temperature to 1.5 lifetimes. This paper details the repair design and summarizes the results obtained in the proof of concept program.     

Parameter estimation of an aeroelastic aircraft using neural networks

Application of neural networks to the problem of aerodynamic modelling and parameter estimation for aeroelastic aircraft is addressed. A neural model capable of predicting generalized force and moment coefficients using measured motion and control variables only, without any need for conventional normal elastic variables or their time derivatives, is proposed. Furthermore, it is shown that such a neural model can be used to extract equivalent stability and control derivatives of a flexible aircraft. Results are presented for aircraft with different levels of flexibility to demonstrate the utility of the neural approach for both modelling and estimation of parameters.     

Role of Fuzzy Approach towards Fault Detection for Distributed Components

Component-based software development is rapidly introducing numerous new paradigms and possibilities to deliver highly customized software in a distributed environment. Among other communication, teamwork, and coordination problems in global software development, the detection of faults is seen as the key challenge. Thus, there is a need to ensure the reliability of component-based applications requirements. Distributed device detection faults applied to tracked components from various sources and failed to keep track of all the large number of components from different locations. In this study, we propose an approach for fault detection from component-based systems requirements using the fuzzy logic approach and historical information during acceptance testing. This approach identified error-prone components selection for test case extraction and for prioritization of test cases to validate components in acceptance testing. For the evaluation, we used empirical study, and results depicted that the proposed approach significantly outperforms in component selection and acceptance testing. The comparison to the conventional procedures, i.e., requirement criteria, and communication coverage criteria without irrelevancy and redundancy successfully outperform other procedures. Consequently, the F-measures of the proposed approach define the accurate selection of components, and faults identification increases in components using the proposed approach were higher (i.e., more than 80 percent) than requirement criteria, and code coverage criteria procedures (i.e., less than 80 percent), respectively. Similarly, the rate of fault detection in the proposed approach increases, i.e., 92.80 compared to existing methods i.e., less than 80 percent. The proposed approach will provide a comprehensive guideline and roadmap for practitioners and researchers.     

航母设计选材及腐蚀控制需求

航母作为人类有史以来最大的军事装备,是一项复杂的巨系统工程,使用的材料种类繁多,工作环境复杂。针对航母使用的苛刻环境条件,介绍了航母用材的通用选材原则,并且对船体结构材料、管路及附件材料的特殊选材要求分别进行了阐述。介绍了航母用材的腐蚀特点:一是腐蚀环境多样,防护要求高,防腐设计难度大;二是系统组成复杂,设备数量多,腐蚀故障影响大;三是舱室结构复杂,施工空间小,防腐修理难度大。针对腐蚀特点提出了航母用材的腐蚀控制需求,从腐蚀控制技术体系、腐蚀控制手段、材料防腐蚀性能3个方面阐述了航母用材的不足和差距,并针对性地提出了航母用材腐蚀控制的建议和对策。     

压缩冷凝机组试验装置中量热器的研究及运用

介绍了压缩冷凝机组试验装置的试验方法;分析了使用制冷剂液体流量计法的试验装置,并针对量热器调节的稳定性,提出了调整措施,为相关试验装置提供了设计依据。     

Equipment for Testing Sheet Structural Materials under Biaxial Tension. Part 2. Testing by Biaxial Loading in the Plane of the Sheet

We analyze specific features of the design of equipment used for mechanical testing of sheet structural materials under the conditions of biaxial static, cyclic, or dynamic loading. We propose original solutions of the problems related to the fatigue testing of crosslike specimens performed without using complex hydraulic systems and their dynamic testing carried out by using very simple testing machines for uniaxial tension–compression.     

新支线飞机供电系统航电接口仿真器设计

为了满足新支线飞机ARJ21供电系统地面独立试验的需要,设计了用于模拟航空电子系统、发动机系统等与电气系统之间相关接口功能的仿真器,为电气系统提供其它飞机系统的仿真信号并指示供电系统的运行状态.为验证供电系统的各项性能提供支持.实际运行结果表明在新支线飞机ARJ21供电系统的12种状态下仿真器对导光板和供电系统的控制逻辑正确,对电源系统简图页和EICAS信息指示合理,通过ARINC429总线与各发电机控制器的通信正常,各项功能与飞机系统设计一致,完全能够满足飞机供电系统综合试验的要求.     

A buckling-based metrology for measuring the elastic moduli of polymeric thin films

As technology continues towards smaller, thinner and lighter devices, more stringent demands are placed on thin polymer films as diffusion barriers, dielectric coatings, electronic packaging and so on. Therefore, there is a growing need for testing platforms to rapidly determine the mechanical properties of thin polymer films and coatings. We introduce here an elegant, efficient measurement method that yields the elastic moduli of nanoscale polymer films in a rapid and quantitative manner without the need for expensive equipment or material-specific modelling. The technique exploits a buckling instability that occurs in bilayers consisting of a stiff, thin film coated onto a relatively soft, thick substrate. Using the spacing of these highly periodic wrinkles, we calculate the film's elastic modulus by applying well-established buckling mechanics. We successfully apply this new measurement platform to several systems displaying a wide range of thicknessess (nanometre to micrometre) and moduli (MPa to GPa).     

某国际机场飞机地面空调机组的研制及其关键技术

以电能为动力的外接式空调机组代替飞机自带的以消耗航空燃油为动力的APU装置,可以降低飞机的运行成本,同时可以改善机场环境。本文阐述飞机外接式空调机组在结构、系统和控制等方面所采用的关键技术,并将这些技术应用于研制飞机地面空调机组,经试制和测试发现,该机组降温速度快、送风温度稳定、安全可靠,能够达到替代机载APU的要求,并将其成功应用于某国际机场。     

Acceptance testing and routine quality control in general radiography: mobile units and film/screen fixed systems

This study presents the findings from acceptance testing and routine quality control (QC) of general radiographic X-ray equipment in Ireland during 2006 and early 2007, including mobile X-ray units and film/screen fixed systems. Acceptance testing and routine QC of the diagnostic X-ray imaging equipment are requirements of European and Irish legislation. One hundred general radiographic X-ray systems were tested within Ireland, 73% of them failed to meet the required QC guidelines, whereby one or more faults were identified. The majority of these failures were minor ones, requiring attention by the suppliers at the next routine service. Significant faults were only identified in seven systems. The suppliers were requested to investigate these issues as soon as possible and take the necessary corrective action. A review of the QC results highlights the need to perform comprehensive acceptance and routine testing of the systems.     

A digital thread approach to support manufacturing-influenced conceptual aircraft design

This paper proposes and demonstrates the integration of manufacturing and production considerations with traditional aircraft design metrics to support affordability-based design. To enable the necessary multi-disciplinary trades, a digital thread approach is proposed that integrates detailed models and analyses. The digital thread refers to linking models from various disciplines through common inputs and data flows with the goal of speeding design time and enabling trades across traditionally isolated disciplines. When used within an overarching design process, the production cost, rate, and efficiencies of non-conventional designs in variable demand environments can be quantified and traded early in the design process. In particular, the methodology is demonstrated using a wingbox design problem such that aircraft performance considerations, production rate, manufacturing cost, and financial planning metrics can be traded within a parametric, visual trade-off environment. The environment, combined with a multi-objective optimization routine, facilitates effective affordability-based tradespace exploration during the early stages of the design of non-traditional aircraft (e.g., those utilizing composite structures) under demand variability. An F-86 Sabre redesigned wingbox using three separate manufacturing concepts is used as a proof-of-concept for this research.     

Applications of fractography for aircraft defect causal analysis

Aircraft maintainers and accident investigators routinely seek advice from materials scientists and engineers about the cause of cracks and fractures in air vehicle components. Experience has shown that further failures are more likely to be avoided if the fractographic assessment is carried out in lockstep with the wider evaluation of relevant engineering and operational factors. If possible the fractographer should be in a position to understand the function of the defective component and should be able to assess how this might be affected by the operation of the aircraft system as a whole, and how failure of the component might affect operation of the aircraft. This paper provides evidence from a set of investigations that support the need for a systems approach to failure analysis of aircraft structure and propulsion component defects when causal factors are complex. Effective failure avoidance can be achieved in this way.