Using built-in-test to reduce TPS run times and improve TPSreliability

This paper addresses using information derived from Built-in-Test (BIT) to fault diagnose Units Under Test (UUTs), wherever possible. This philosophic approach to diagnostic testing is not new. It has been studied over the past 20 years under the visor of “Integrated Diagnostics”, but it has yet to be truly implemented in a “real life” military diagnostic test environment. The mindset of Test Program Set design engineering, along with customer and contractor management alike, remains “complete diagnostic testing based upon single catastrophic component failure modes”. If we are to generate cost efficient Test Program Sets (TPSs) under reduced military budget constraints, this will have to change! The test engineer must be encouraged to use methodologies to speed up development time and decrease TPS run times. Using present technology, this is possible now, and as the technology matures, will become a truly viable approach in the future. For the purpose of this paper, the author relies heavily on his extensive US Navy Automatic Test Equipment (ATE) and Test Program Set (TPS) experience, as well as on previous studies performed on using BIT to fault diagnose Unit Under Test failures on US Naval Air weapon systems     

Aircraft Stores Interface Manual (ASIM) adopts paperlessinformation technology

During recent years, defense budgets have been cut across all services while the cost of maintaining current standards has risen. The Aircraft Stores Interface Manual (ASIM) Program Office found that maintaining a staff for paper updates was no longer feasible and was tasked by the North Atlantic Treaty Organization (NATO) Air Armament Working Party (AAWP) to digitize the ASIM manuals. Converting this information from paper to electronic media presented several challenges which are discussed. Adopting Paperless Information Technology and replacing “Snail Mail” with the World Wide Web is presented     

Proposal to TPS delivery in 4 months?

Decreasing the often lengthy Test Program Set (TPS) development time is a high priority for both DoD and commercial industry. A protracted test development time for a commercial product can make or break its success. It can impact time-to-market goals for a product, which in turn, can result in a loss of market share. Though the DoD world has different objectives, they, too, are concerned with long test development times which can increase costs and jeopardize a weapon system's mission readiness. The case study for this paper is a test system developed by BAE Systems in less than four months to meet a commercial customer's stringent schedule requirements. The factors that contributed to the success of this project are examined, as is their relevance to the DoD world. The desire is to apply relevant lessons learned from the commercial industry to DoD programs, yielding a decrease in TPS development time     

Multifunctional structures technology experiment on Deep Space 1Mission

Lockheed Martin Astronautics has developed the Multifunctional Structure (MFS) concept as a new system for spacecraft design that eliminates chassis, cables, connectors and folds the electronics into the walls of the spacecraft. Concurrent engineering will be essential to integrate the electronic, structure, and thermal design. Design methodologies are in work to manage all power, grounding and shielding concerns. The MFS approach offers significant savings in mass and volume and supports the “faster-better-cheaper” philosophy in new spacecraft programs. The technology will be demonstrated as an experiment on the New Millenium Program Deep Space 1 (DS 1) mission     

The realism of FAA reliability-safety requirements and alternatives

As avionic systems become more complex, realistic qualification requirements for the flight-critical systems becomes more important, but more difficult to define. Requirements developed to establish acceptable levels of performance must be verifiable if they are to have any meaning. This article shows that both the current FAA requirements of flight-critical systems and the FAA recommended methods for probabilistic assessment are flawed, and result in “required” safety assessments which are misleading. Alternatives are then explored     

A sky high education

Getting an engineering education doesn't have to be restricted to a desk or terra firma. University students, and even some high school students, can participate in the NASA Reduced Gravity Student Program conducting experiments in zero gravity aboard the infamous “Vomit Comet.” This airplane was an unseen player in the Apollo 13 movie that provided weightlessness for star Tom Hanks in this outstanding film     

Proposal Perfidy, A Poverty Syndrome (Ethics as a Prerequisite to Proposal Success)

There is a direct correlation between proposal success and proposal ethics, a fact which is independent of the proposal scope or the type of customer. To be successful, a proposal must result in a profit when measured within the total environment of present and future sales. A misleading or unethical proposal has little chance of leading to an immediate contract, is most likely to incur cost penalties if a contract does result, and is certain to reduce the probabilities for future sales. Unfortunately proposals tend to deal in that gray area between fact and fiction; the normal desire to present things in their most favorable light leads to misrepresentation. In his own professional interests the proposal engineer must learn to give an honest and accurate portrayal of his plan and his product.     

抓住机遇迎接挑战实现航空动力跨越发展

发动机是飞机的“心脏”，是推动飞机的整个航空工业蓬勃发展的源动力。我国航空动力相对落后，已成为制约航空工业发展和军民用飞机更新换代的“瓶颈”技术之一。造成这种局面的原因很多，值得我们认真反思，总结经验教训。虽然我国至今尚没有一台发动机走完自行研制的全过程并装备部队，但通过半个世纪的努力，我国具备了一定的研制新机能力和快速发展的技术基础。面对新世纪，挑战和机遇并存，我们必须因势利导，抓住机遇，实现航空动力的跨越发展。本文对此提出了措施和建议。     

Censoring sensors: a low-communication-rate scheme for distributeddetection

We consider a new scheme for distributed detection based on a “censoring” or “send/no-send” idea. The sensors are assumed to “censor” their observations so that each sensor sends to the fusion center only “informative” observations, and leaves those deemed “uninformative” untransmitted. The main result of this work is that with conditionally independent sensor data and under a communication rate constraint, in order to minimize the probability of error, transmission should occur if and only if the local likelihood ratio value observed by the sensor does not fall in a certain single interval. Similar results are derived from Neymarr-Pearson and distance-measure viewpoints. We also discuss simplifications for the most interesting case that the fusion center threshold is high and the communication constraint is severe. We compare censoring with the more common binary-transmission framework and observe its considerable decrease in communication needs. Finally, we explore the use of feedback to achieve optimal performance with very little communication     

Aerospace Capability and Systems Analysis Applied to Urban Problems?Some Views from a Social Scientist

Much has been written about the development of a general systems theory for application to civil problems, but very little documentation exists in the sense of case studies of large-scale programs implemented using the systems approach. The Model Urban Neighborhood Demonstration Program, operating in an inner-city poverty neighborhood in Baltimore, offers some lessons in this regard. With the present state of the art, the techniques of systems analysis are most effective at the subsystem level, and the necessary funding and development time should be afforded to extend their usefulness in the civil order. Existing aerospace companies provide an operating institutional base, with extenasive resources, that can be beneficially translated to solving problems in the public order.     

面向Flash存储器的FAT文件系统可靠性增强机制

FAT文件系统针对Flash存储器使用时,其FAT表存储位置不确定且各个簇之间的擦写次数不均衡,导致其可靠性降低.针对上述问题,提出了两种解决方案,分别是FAT表可控迁移和空闲簇磨损均衡.前者在Flash上预留多个块存储FAT表,每次更新FAT表时在其中选择擦除次数最小的块,预留一个块记录最新FAT表的入口地址;后者在Flash上预留一个块记录FAT表中各个簇的擦写次数,每次分配空间时选择擦写次数小于擦除阈值的空闲簇.测试结果表明,改进后的FAT文件系统能够在可控范围内可靠地存储FAT表,同时有效地均衡了各个簇的擦写次数,这些都增强了FAT文件系统的可靠性.     

Multi-computer VXIbus system set up and use

VXI has matured into a flexible bus architecture with which to develop various types of instrumentation systems. This paper details the multi-computer approach used in the VXI-based system that CACI developed for the Air Force. The system, the Engine Test/Trim Automated System II (ETTAS II) is designed to test: all Air Force jet engines. The paper discusses how to integrate multiple computers in a VXI-based system, including discussions on: setting up the computers; selecting register-based versus message-based computers; setting up and using shared-memory; defining and separating tasks for each computer. The shared memory discussion talks about different ways to structure the shared memory, including setting up a system-level “Current-Value Table” (CVT) for all instruments, as well as how other devices, including another computer can access the shared memory space. The paper shows how Commercial-Off-the-Shelf (COTS) software products NI-VXI, LabVIEW, and NI-VISA (National Instruments) can be used to satisfy all these requirements. The paper shows how the multi-computer approach can be cost-effective in many cases     

军用涡喷涡扇发动机低温起动试验的优化

介绍了军用涡喷、涡扇发动机在高空台上进行低温起动试验的试验设备、被试发动机、试验方法和试验结果。该试验是发动机高空模拟试验中最难完成的试验之一，要满意地完成低温起动试验必须具有较高稳定工作裕度的发动机；试验设备、测试设备必须配套、安全、可靠；应对低温起动试验程序进行优化。     

Testing the precision lightweight GPS receiver

Innovative field testing techniques are employed at Holloman Air Force Base to help the Global Positioning System (GPS) NAVSTAR Joint Program Office (JPO) test the Precision Lightweight GPS Receiver (PLGR). Characterizing the PLGR's accuracy in dynamic environments is of prime importance but testing also prescribes the evaluation of its ability to receive differential GPS corrections, real time, and its Electronic Counter Counter Measures. To meet these goals, the 46th Test Group provides the C-12 cargo aircraft for flight testing, an instrumented test van for mobile testing, the High Speed Test Track for high velocity testing, a UH-1 helicopter for rotor blade modulation testing, and special PC laptops for ground troop testing. All of these test capabilities utilize Holloman's well instrumented test environments with thousands of surveyed sites validated by the Defense Mapping Agency. This paper emphasizes the testing techniques that are helping to define Test & Evaluation methodologies for the changing world where Global Positioning with NAVSTAR is becoming a reality     

Sensor/actuator failure detection in the Vista F-16 by multiplemodel adaptive estimation

Multiple model adaptive estimation (MMAE) is applied to the Variable-In-flight Stability Test Aircraft (VISTA) F-16 flight control system at a low dynamic pressure flight condition (0.4 M at 20000 ft). Single actuator and sensor failures are addressed first, followed by dual actuator and sensor failures. The system is evaluated for complete or “hard” failures, partial or, “soft” failures, and combinations of hard and soft actuator and sensor failures. Residual monitoring is discussed for single and dual failure scenarios. Performance is enhanced by the application of a modified Bayesian form of MMAE, scalar residual monitoring to reduce ambiguities, automatic dithering where advantageous, and purposeful commands     

Commercial ATS program management

With the defense industry's ever-increasing reliance on Commercial-Off-The-Shelf (COTS) Automatic Test Systems (ATS) and commercial suppliers, there is a need to recognize and actively manage the gap between the expectations of the defense industry and the commercial community. The key to a successful program has proven to be investing time during the proposal stage and at contract award to clearly define the COTS deliverables and the level of detail of required data. This requires discipline from the supplier (engineering, sales, and the proposal team) as well as the procuring agency to agree that the time investment is worthwhile. This paper examines the problem and outlines proven strategies in managing this gap.     

New approaches to weapon system testing or “back to thefuture”

This paper proposes abandoning the use of multipurpose ATE for “horizontal” support of weapon systems in favor of returning to “vertical” support. An R&D effort is proposed to develop a software “hot mock-up” system for field testing weapon system assemblies     

Shared technologies: a new roadmap

The long-term goal of the USAF Shared Technologies Program is to facilitate the development of a roadmap for technology insertion on the wide variety of legacy Automatic Test Equipment (ATE) accumulated by the USAF over the past 30 years. A successful roadmap will provide for Operation & Support (O&S) cost reduction, preserve Test Program Set (TPS) development investments, and evolve in concert with the DoD Executive Agent for Automatic Test Systems (ATS) initiatives and commercial industry, and (e.g., NxTest) changes. The near-term objective of this phase of the USAF Shared Technologies Program is to demonstrate the feasibility of incorporating available commercial technology into the Radio Frequency (RF) Mobile Electronic Test Set (RFMETS). The RFMETS was originally delivered to the USAF during the early 1990s and is used to support a variety of C-130 avionics including the APQ-170 and APQ-180 Radar Systems.     

A methodology for evaluating, comparing, and selecting softwaresafety and reliability standards

The regulated industries, which in the FDA's (US Food and Drug Administration) case include the manufacturers of food, cosmetics, pharmaceuticals, and medical devices, are responsible for selecting and justifying the selection and use of appropriate national and/or international consensus standards. This paper documents the results of a scientific inquiry which was undertaken to develop a methodology to evaluate and select individual standards as well as compatible sets of standards. Initially the scope was limited to software safety and reliability standards. Since then it has been expanded to other areas. It was found that six categories of criteria are important when evaluating the potential use of software safety standards: General Factors, Product Characterization, Process Characterization, Personnel Characterization, Risk Management, and Overall Standards Framework. The criteria in each of the six categories must be addressed, How they are addressed is both a technical and a policy decision. The goal should not be to try to find the “ultimate” standard because there isn't any. Rather the goal should be to select a balanced “diet” of standards based on these six categories. The methodology provides a systematic framework from which to make an objective determination about the appropriateness of using a particular standard