Reliability HotWire: eMagazine for the Reliability Professional
In this issue:

Issue 48, February 2005

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

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Hot Topics

Using BlockSim to Analyze Systems That Do Not Operate 24 Hours per Day

In many production lines, the manufacturing operation is not a 24-hour operation, but a partial-day operation (e.g. 8 hours or 16 hours per day) in which maintenance crews are required to continue their work even beyond the end of a shift. In this article, we will discuss using BlockSim to model and simulate such systems. The key for modeling this type of scenario is to incorporate a time block that handles the "clock" of the system and makes the operation stop for a certain duration (or percentage) of the time, while allowing the crews to continue their work.

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Reliability Basics

Beta Binomial Confidence Bounds on the Mixed Weibull Distribution

The mixed Weibull distribution is used to model data that do not fall on a straight line on a Weibull probability plot. Data of this type, particularly if the data points follow an S-shape on the probability plot, may be indicative of more than one failure mode at work in the population of failure times. This article describes how the beta binomial method is used to estimate the confidence bounds for such analyses.

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Tool Tips
  • How can I view the properties of all blocks simultaneously in BlockSim?

  • In Weibull++, when fitting a distribution with a location parameter, should the location parameter always be equal to the minimum failure time?

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Hot News

2005 International Applied Reliability Symposium: "Sharing Applications, Success Stories and Lessons Learned in Reliability and Maintainability Engineering." The ARS Board of Directors is pleased to announce Vice Admiral Scott Fry United States Navy (Retired) as the keynote speaker for this years Symposium. He is currently acting as Group Senior Vice President and manager of the Strategic Systems Group for Alion Science and Technology. The Symposium will be held May 1820, 2005 at the Catamaran Resort on Mission Bay in San Diego, California. ARS 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. Early registration is recommended and available at:

n addition, the Symposium event details are growing! You can now navigate the ARS 2005 Program Matrix by Title, Presenter or Session ID. Further exploration will then lead to presentation overviews. Please visit the Symposium website at to learn more.


ARS 2005 Sponsorship This years International Applied Reliability Symposium is offering a creative way to help your company demonstrate its commitment to reliability engineering. The ARS 2005 introductory sponsorship package provides your company with targeted visibility while also allowing a number of your engineers to attend the event at no additional cost. Send a quick message to if you are interested in benefiting your company and the engineering team with this simple solution.


ReliaSoft Scientist Presenting in France Mr. Adamantios Mettas, Senior Scientist, will be presenting a paper on Accelerated Life Test Analysis at this years QUALITA 2005 conference in Bordeaux, France. The event dates are March 16 - 18, 2005. Mr. Mettas will be presenting on Thursday the 17th. For more information about this reliability and maintainability conference, please visit:


Enhanced Reliability Prediction - ReliaSoft has always stressed the importance of performing reliability assessments based on the results of testing from in-house labs and data pertaining to the performance results of the product in the field. We also recognize that reliability prediction stands at the center of many reliability programs across government and industry. Therefore, we currently offer an entire suite of quantitative analysis software tools and RACs prediction software, PRISM. ReliaSoft is also finalizing the newest addition to our suite of software, Lambda Predict for standards based reliability prediction with any of the major prediction standards. If your current business model mandates the use of reliability prediction and you want to utilize your more accurate in-house data too, then ReliaSoft offers the best of both worlds.


Chinese MSMT Training - ReliaSoft China will be holding a localized MSMT training seminar in Shenzhen, China this coming March 2005.  For complete details in Chinese, please visit:


Regional Symposia - The annual International Applied Reliability Symposium is held in the USA. In addition to this event, regional Applied Reliability Symposia combine both regional presenters, addressing needs and applications specific to that region, and international presenters. Rio de Janeiro, Brazil will be the first host of such an event this coming June 16 17, 2005. An official call for papers and additional information can be reviewed at:


 Public Training Event Calendar

February 2005
February 28 - March 4, 2005: MSMT Foundations in Tucson, Arizona
February 28 - March 4, 2005: MSMT Foundations in Istanbul, Turkey
March 2005
March 7 - 8, 2005 Failure Modes, Effects and Criticality Analysis and Xfmea in Melbourne, Australia
March 14 - 18, 2005: MSMT Foundations in Warsaw, Poland
April 2005
April 4 - 6, 2005: Advanced System Reliability, Maintainability and Availability Analysis in Tucson, Arizona
April 7 - 8, 2005: Failure Modes, Effects and Criticality Analysis and Xfmea in Tucson, Arizona
April 25 - 29, 2005: MSMT Foundations in Tucson, Arizona
April 27 - 29, 2005: Advanced System Analysis and BlockSim in Singapore
May 2005
May 2 - 6, 2005: MSMT Foundations in Melbourne, Australia
May 18 - 20, 2005: 2005 International Applied Reliability Symposium in San Diego, California
More Reliability Training Seminars...


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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