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

Issue 33, November 2003

*Hot Topics
*Reliability Basics
*Tool Tips
*Latest Software Updates
*Hot News
*Contribute to HotWire

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Hot Topics  
The Latest Release of BlockSim, Version 6.2, Contains More Powerful Capabilities:
BlockSim 6.2, the latest service release for Standard and FTI editions, is a free upgrade for all current BlockSim 6 users. For free BlockSim 6 product updates, see
  • Expanded Algebraic Solutions for RBDs and FTDs
    BlockSim 6 is unique among reliability block diagram (RBD) software because it is the only software package with the analytical power to provide the complete algebraic solution for even the most complex systems. In addition to the complete reliability equation, BlockSim version 6.2 now provides both the complete algebraic pdf and failure rate function for such systems.

    To read more, see 


  • Ability to Edit Item Properties in Separate Worksheets
    A block (or an event) in BlockSim has hundreds of specific properties that can be set via the Block Properties windows. The additional ability to edit these properties in a spreadsheet format has been requested by multiple BlockSim users. To address this, the latest release of BlockSim, version 6.2, includes an intelligent and customizable properties table called the Item Properties Table.  

    To read more, see 
Reliability Basics  

Maximum Likelihood Function

In a previous Hotwire article, we took a look at probability plotting. The rank regression or least squares parameter estimation method essentially "automates" the probability plotting method mathematically. In this article, we will take a look at the maximum likelihood estimation (MLE) method. This is considered to be one of the most robust parameter estimation techniques.

To read more, see 

Tool Tips  
  • What are the dates and locations for ReliaSoft's 2004 public reliability training seminars?

  • When using the Weibull distribution, why does it seem that the mean increases as the value of beta decreases (0 < beta < 1) for a constant value of eta?

  • Why doesn't BlockSim allow for the rolling up of system reliability uncertainty using confidence limits on the individual component parameters?

To read more, see 

Latest Software Updates
New service releases are now available for BlockSim (SR 6.2.1) and Xfmea (SR 1.0.6). To determine the compile revision of the application on your computer, select About from the Help menu.


Application Date Created Version
BlockSim 10/17/03 6.2.1
BlockSim Update 10/17/03 SR 6.2.1
Xfmea 11/6/03 1.0.6
Xfmea Update 11/6/03 SR 1.0.6
Hot News
* RGA 6 Standard & RGA 6 PRO Software Update - ReliaSoft's newest reliability growth software is currently undergoing rigorous validation testing and minor software enhancements. The developers are diligently working to have it completed by the end of this year. For information on RGA 6 features and pricing, see:
* The 2004 Applied Reliability Symposium (ARS) - The 2004 Symposium theme is "Sharing applications, success stories and lessons learned in reliability and maintainability engineering." Please visit the Symposium Web site is at for information on early registration, topics and presenting organizations.
* ReliaSoft's Consultants Meet a Variety of Needs - You all know ReliaSoft as a world class developer of reliability analysis tools. We also have an expert team of consultants who are ready to assist you in the areas of quality and reliability engineering. ReliaSoft consultants can provide expertise in any of the following areas:
  • Complete Reliability Program Development
  • Test and Experiment Design
  • Data Analysis and Reporting
  • Developing, Evaluating and Communicating Reliability Requirements
  • Equipment Reliability, Maintainability and Availability Assessment
  • Theoretical Development

We realize that under today's economic conditions, company reliability resources are stretched to the limit and that you may not have the time to take on another project. Whether you have a large project you can't find time for or merely need another set of eyes to review your analysis or report, please consider giving us a call. We would be happy to discuss your requirements and promptly provide you with a cost and time estimate for completion of the project. Consultant biographies and client lists are available at

* 50th Annual Reliability & Maintainability Symposium - ReliaSoft will be present to help celebrate RAMS' 50th anniversary on January 26 - 29, 2004. This Reliability and Maintainability Symposium will be held at the Airport Marriott Hotel in Los Angeles, California. Current state-of-the-art methods for achieving R&M objectives, plus historical perspectives on the last 50 years of R&M, will be presented. For more information and an Advanced Program, see
* Calendar of Public Events:


Master the Subject, Master the Tools Training Seminar (MSMT) - Life data analysis, accelerated life data analysis and system analysis: November 17 - 21, 2003 in Tucson, AZ. For more information, see
December QALT Boot Camp - December 10 - 12, 2003 in Tucson, AZ. This intensive three day course covers advanced topics, concepts and applications of quantitative accelerated life testing (QALT) analysis and ReliaSoft's ALTA PRO software. For more information, see
Singapore - Master the Subject, Master the Tools Training Seminar (MSMT) - Life data analysis, accelerated life data analysis and system analysis: December 8 - 12, 2003 in Singapore. For more information, see

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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