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Aerospace and Electronic Systems Magazine, IEEE

Issue 3 • Date March 2009

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  • IEEE Aerospace and Electronic Systems Magazine

    Publication Year: 2009 , Page(s): c1
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  • This month's covers ...

    Publication Year: 2009 , Page(s): c2
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  • Contents

    Publication Year: 2009 , Page(s): 1
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  • In This Issue - Technically

    Publication Year: 2009 , Page(s): 2
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  • From the editor-in-chief [Society News & Information]

    Publication Year: 2009 , Page(s): 3
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  • Intelligent SINS/RDSS integrated algorithms for land vehicle navigation

    Publication Year: 2009 , Page(s): 4 - 11
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3920 KB) |  | HTML iconHTML  

    This is a discussion of the design of strap-down inertial navigation systems (SINS) and radio determination satellite service (RDSS) integrated navigation algorithms. The research aims at testing the effectiveness of artificial intelligence (AI)-aided Kalman filtering (KF) approaches for land vehicle applications. A back-propagation neural network (BPNN)-aided K*F algorithm and a fuzzy inference-based KF algorithm are presented in order to overcome the time delay of RDSS positioning provided by a double-star positioning system in China. Traditional KF causes biased solutions, and indeed, leads to filter instability easily since the time delay of RDSS positioning, in an active mode, is hard to be modeled and sometimes suffers from RDSS outages. Therefore, a fuzzy inference is used to correct the variance matrix of KE measurement noises adaptively; and a trained BPNN corrects the outputs of the Kalman filter. The algorithms proposed herein have been verified on real SINSIRDSS data. collected in land vehicle tests and are compared with other approaches. The results demonstrate that fuzzy inference-based KF algorithms improve the positioning accuracy to over 40 % better than KF algorithms, and BPNN-aided KF algorithms have the same precision as GPS which is the reference station In dynamic experiments without RDSS outages. The test results with RDSS outages indicate that the fuzzy inference-based KF is feasible but with positioning errors of hundreds of meters, so the BPNN-aided KF is designed to efficiently compensate for RDSS outages and improve system performance. View full abstract»

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  • Experiences in managing the Prometheus Project

    Publication Year: 2009 , Page(s): 12 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6903 KB) |  | HTML iconHTML  

    Congress authorized NASA's Prometheus Project in February 2003, with the first Prometheus mission slated to explore the icy moons of Jupiter. The project had two major objectives: 1) to develop a nuclear reactor that would provide unprecedented levels of power and show that it could be processed safely and operated reliably in space for long-duration, deep-space exploration; and 2) to explore the three icy moons of Jupiter - Callisto, Ganymede, and Europa - and return science data that would meet the scientific goals as set forth in the Decadal Survey Report of the National Academy of Sciences. Early in project planning, it was determined that the development of the Prometheus nuclear-powered spaceship would be complex and require the intellectual knowledge residing at numerous organizations across the country. In addition, because of the complex nature of the project and the multiple partners, approaches beyond those successfully used to manage a typical JPL project would be needed. This describes the key experiences in managing Prometheus, which should prove useful for future projects of similar scope and magnitude. View full abstract»

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  • How engineers can conduct cost-benefit analysis for PHM systems

    Publication Year: 2009 , Page(s): 22 - 30
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5822 KB) |  | HTML iconHTML  

    Individuals who work in the field of Prognostic and Health Management (PHM) technology have come to understand that PHM can provide the ability to effectively manage the operation, maintenance, and logistic support of individual assets or groups of assets through the availability of regularly updated and detailed health information. Naturally, prospective customers of PHM technology ask: "How will the implementation of PHM benefit my organization?" Typically, the response by individuals in the field is: "Anecdotal evidence indicates that PHM decreases maintenance costs, increases operational availability, and improves safety." This information helps the prospective customer understand the practical benefits of the technology, but that customer stills needs more information to justify their investment in the technology. The customer needs a calculated return on investment (ROI) figure for their particular asset that provides financial assessment of the benefit of the investment. The data, time, and expertise required to conduct a rigorous cost benefit analysis makes the effort seem daunting to the average engineer with little to no fimancial analysis training. The reality is that with a cursory understanding of the asset operation, maintenance, and logistic issues, a useful cost-benefit analysis can be conducted by engineers without business school training. Our purpose herein is to provide a general methodology for conducting a preliminary cost-benefit analysis that calculates an ROI for PHM implementation. We discuss the general types of information needed for the analysis, the quantifying of expected benefits, and the types of supporting data required to validate the benefit assumptions as well as an outline for the costing of PHM technology. View full abstract»

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  • Integrating modular avionics: A new role emerges

    Publication Year: 2009 , Page(s): 31 - 34
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2672 KB) |  | HTML iconHTML  

    Traditionally, airplane systems have been designed and implemented in a federated fashion with each system providing for its own needs. A typical airplane system could be made up of one or more black boxes each having its own enclosure and providing for its own power conditioning and cooling needs. I/O signal conditioning and computational processing necessary to provide the intended function is also provided on a box-by-box basis. With each new generation of airplanes, the number of systems increased. Driven by market forces the need grew to reduce weight and electrical power to keep the airplane fuel efficient, cost-effective, and competitive. To address this contradiction, the Integrated Modular Avionics (IMA) concept was born. Within IMA architectures, avionics functions share common resources. Multiple black boxes are optimized to the minimum IMA resources necessary. This optimization provides the sought-after weight and power savings, and also provides for a much reduced number of parts to be maintained and controlled. These are all beneficial for the airplane manufacturer and airplane operator. However, MIMA architectures present some unique challenges during their development and integration. This will explore some of the more significant of these integration challenges associated with IMA architectures, including: What is the system? For the supplier whose system has been selected to be hosted on the IMA platform, the boundaries can be unclear. What was once a box with circuit cards and substance has been abstracted to a software application. Connection to other systems or to sensorsteffectors was via airplane wiring. Now, complex in-line electronics modules exist that the supplier knows little or nothing about. For the provider of the IMA platform, the system may be defined as a set of available resources (processing, communication, 1/0, etc.) to be shared by the systems to be hosted. To the airplane manufacturer the system is a working suite of avionics. - With the LMA approach: "Who is responsible for ensuring that boundaries and expectations are clearly defined and understood so that nothing gets overlooked?" Who is the system integrator? Within the IMA environment the answer changes depending on your perspective. The supplier of a hosted function may be considered responsible for the integration of their system components. The IMA platform provider may believe they are responsible for the platform elements. The airplane manufacturer wants an integrated solution. With the IMA approach: "Who is responsible for ensuring that the whole is equal to the sum of its parts?" How is the integration of an IMA architecture handled? As more and more of the hosted systems are brought together, IMA architectures can present challenges not seen with federated systems. The nature of IMA architectures requires more of the components to be available and working to allow seemingly simple tasks to take place. With the IMA approach: "Who is responsible for ensuring that this integration is planned and executed in the optimum sequence?" View full abstract»

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  • Derating concerns for microprocessors used in safety-critical applications

    Publication Year: 2009 , Page(s): 35 - 40
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3912 KB) |  | HTML iconHTML  

    The use of commercial-off-the-shelf (COTS) microprocessors for safety-critical applications usually implies derating of the device to make it work in harsh environments. We discuss derating concerns for state-of-the-art microprocessors. Issues addressed herein include noise margins due to low voltage levels, multiple power supplies, frequency and current derating concerns, error sources, timing degradation, power-aware architectures, and new advanced microprocessor derating features. View full abstract»

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  • Non-linear sequencing

    Publication Year: 2009 , Page(s): 41 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3768 KB) |  | HTML iconHTML  

    Spacecraft are traditionally commanded using linear sequences of time-based commands. Linear sequences work fairly well, but they are difficult and expensive to generate, and are usually not capable of responding to contingencies. Any anomalous behavior while executing a linear sequence generally results in the spacecraft entering a safe mode. Critical sequences like orbit insertions which must be able to respond to faults without going into safe mode are particularly difficult to design and verify. The effort needed to generate command sequences can be reduced by extending the vocabulary of sequences to include more sophisticated control constructs. The simplest extensions are conditionals and loops. Adding these constructs would make a sequencing language look more or less like a traditional programming language or scripting language, and would come with all the difficulties associated with such a language. In particular, verifying the correctness of a sequence would be tantamount to verifying the correctness of a program, which is undecidable in general. We describe an extended vocabulary for non-linear sequencing based on the architectural notion of cognizant failure. A cognizant failure architecture is divided into components whose contract is to either achieve (or maintain) a certain condition, or report that they have failed to do so. Cognizant failure is an easier condition to verify than correctness, and it can provide high confidence in the safety of the spacecraft. Because cognizant failure inherently implies some kind of representation of the intent of an action, the system can respond to contingencies in more robust and general ways. We will describe an implemented non-linear sequencing system that is being flown on the NASA New Millennium Deep Space 1 Mission as part of the Remote Agent Experiment. View full abstract»

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  • The first one Hundred University-Class spacecraft 1981 -2008

    Publication Year: 2009 , Page(s): A-1 - A-24
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (14014 KB) |  | HTML iconHTML  

    In April 2008 the one-hundredth "university-class" spacecraft was launched; 50 were launched in the past four years. A "university-class" spacecraft is defined as one whose mission includes the training of university students in spacecraft engineering. The success of these 100 missions has varied widely; one-fifth were lost to launch failures, one-fifth were deployed but failed almost immediately, while one-quarter of these student-built satellites were operational for at least three years. While none can deny the established fact of student-built spacecraft, there is little discussion in either the education or engineering literature about the merits of this fact. Should universities be in the practice of building and launching their own spacecraft? Given the tremendous costs of building and operating student-built spacecraft as measured in student/faculty hours, dollars, donations, and, especially, the 5-7 year process from concept to launch - are such spacecraft worth the cost? If so, what kinds of missions are best suited for university-class satellites? To answer these questions, this survey draws upon launch records, published reports, and project communications to create a statistical examination of these hundred student-built spacecraft, identifying correlations between reliability, size, and the types of schools building space hardware. In particular, there is a strong distinction between government-sponsored "flagship" universities and "independent" schools lacking strong external support - both in terms of mission relevance and on-orbit performance. Given that distinction, we offer suggestions for independent schools to improve their missions and their orbital success. This information was compiled from online sources, past conference proceedings, and author interviews with students and faculty at many universities, as noted in the references. The opinions expressed herein reflect this author's experience as both student project manager and faculty advis- or to university-class projects. This author accepts sole responsibility for any factual (or interpretative) errors found in this paper. View full abstract»

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  • IEEE Aerospace & Electronic Systems Society Organization

    Publication Year: 2009 , Page(s): 47
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  • Directory of IEEE-AESS Personnel

    Publication Year: 2009 , Page(s): 48
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  • Meetings Calendar

    Publication Year: 2009 , Page(s): c3
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  • [Back cover]

    Publication Year: 2009 , Page(s): c4
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Aims & Scope

The IEEE Aerospace and Electronic Systems Magazine publishes articles and tutorials concerned with the various aspects of systems for space, air, ocean, or ground environments.

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Meet Our Editors

Editor-in-Chief
Teresa Pace, PhD EE
Chief Engineer SenTech
SenTech, LLC - A DSCI Company
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