In this issue:

Issue 81, November 2007

*Hot Topics
*Reliability Basics
*Tool Tips
*Hot News
*Contribute to HotWire

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Hot Topics

Life Data Analysis of Load Sharing Units
Typically in life data analysis, in a population of similar units, it is assumed that unit failures are independent from each other. In other words, one unit's failure does not make the other unit(s) less or more likely to fail. This independence assumption is not always valid, however, as there are cases where a unit's failure affects the failure likelihood of other unit(s). A common example for this type of dependence is the load sharing redundant configuration. Examples of units in such a configuration include pumps, routers and motors. In this article we present an approach for analyzing data obtained from units that are in a load sharing relationship using ALTA 7. The obtained model can also be used in an RBD analyzed in BlockSim 7.

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Reliability Basics

Analyzing Success/Failure Data Using the Crow Discrete Reliability Growth Model
Typical developmental testing reliability growth analysis involves the use of times-to-failure data obtained from the tested system(s) during the development program. Many products or systems, such as missiles and air bags, may not produce times-to-failure data because they are considered one time/usage (or one-shot) systems. Such scenarios require models other than the ones used to analyze times-to-failure data. In this article, we cover the Crow-AMSAA Discrete reliability growth model that is found in RGA 6.

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Tool Tips
  • How can you analyze data sets with more than one failure mode in Weibull++?
  • How can you be sure your software is up to date?

To read more, see 

Hot News
* 54th Annual Reliability & Maintainability Symposium (RAMS) - ReliaSoft Corporation will be a participant and presenter at RAMS again this winter. The event will be held at the Palace Station Hotel & Casino in Las Vegas, Nevada on January 28-31, 2008. This year's Symposium theme: "Dawn to Dusk - Life Cycle Prescriptions." RAMS participants are exposed to a wide variety of papers, tutorials, and panel discussions that share the insight of industry and government leaders. Our staff of reliability experts will be on hand to provide information and demonstrate the capabilities of ReliaSoft's complete suite of tools, including our Web-based XFRACAS application.  We always look forward to seeing our old friends and making new ones; please be sure to stop by our booth! For more information and an advanced program, see
* ReliaSoft's QALT Boot Camp Next Month! - This unique course expands upon the basics in a three-day intensive theoretical and hands-on seminar (utilizing the ALTA PRO software) that exposes the attendee to the advanced concepts, principles and requirements for performing quantitative accelerated life testing. Special focus will be given to multiple case studies illustrating QALT principles and a hands-on workshop where the attendee will solve multiple complex problems involving data from accelerated life tests. By the conclusion of this course, the participant will be thoroughly exposed to QALT and will be able to perform quantitative accelerated life tests as well as analyze data from such tests, including tests utilizing multiple stresses or time-varying stresses (such as step-stress tests). RS 521 will be held December 5 - 7, 2007 in Tucson, AZ. For more details, see

Call for ARS 2008 Presenters - Now that you have spent years developing and polishing your reliability engineering skills, we want you to discuss your experiences with colleagues in the discipline. The 2008 International Applied Reliability Symposium, North America will be held June 17 - 20, 2008 in Reno, Nevada. This annual event provides a forum for expert presenters from industry and government to come together with reliability practitioners from all over the world to discuss the application of reliability principles to meet real world challenges. You are invited to submit presentation proposals that address the Symposium's theme: "Sharing applications, success stories and lessons learned in reliability and maintainability engineering." The primary author for each presentation delivered at the Symposium will receive complimentary registration to the event. For more information and the required proposal submission form, please visit

Some enhancements to the program that have recently been announced for ARS 2008 include:

  • Golf Outing:  Attendees have the option to register for a golf outing on Monday -- networking and socializing while enjoying mountain views.
  • Excellent Presentation Awards Luncheon: A hosted luncheon on Thursday will provide an opportunity for attendees to interact with colleagues (including expert presenters) and we will present monetary awards for the top 3 presentations (as voted by attendees).
  • University Research Presentations: On Friday, the Symposium will offer a full day of academic-oriented presentations, in which leading universities will present on their latest research and discoveries.

For more information, visit

Upcoming Public Training Event Calendar
November 2007
November 15 - 16, 2007: RS 480 Reliability Centered Maintenance in Tucson, Arizona
November 19 - 23, 2007: MSMT Foundations in Melbourne, Australia
November 26 - 30, 2007: MSMT Foundations in Arcachon, France
December 2007
December 3 - 7, 2007: RS 540 Repairable Systems Analysis in Singapore
December 5 - 7, 2007: RS 521 Advanced QALT in Tucson, Arizona
December 10 - 11, 2007: RS 401(C) Life Data Analysis (Condensed) in Chennai, India
December 12 - 13, 2007: RS 522(C) Advanced System Analysis (Condensed) in Chennai, India
January 2008
January 24 - 25, 2008: RS 401(C) Life Data Analysis (Condensed) in Bangalore, India
Contribute to HotWire
Contributions Welcomed
As always, your feedback and contributions are appreciated. ReliaSoft is able to provide the most user-friendly reliability software packages and support because we listen to our customers. This applies to our newsletters and publications as well. We welcome any suggestions or contributions you may have for Reliability HotWire. If you have a topic or article that you think would be useful to the readers of Reliability HotWire, feel free to contact us.

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