In this issue: Issue 106, December 2009
*Hot Topics
*Reliability Basics
*Tool Tips
*Latest Software Updates
*Hot News
*Contribute to HotWire

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Hot Topics
Reliability Demonstration Tests for Repairable Systems
Reliability demonstration tests for non-repairable systems are well developed and regularly used by reliability engineers. A tool called the Design of Reliability Tests (DRT) that helps users design such tests is included in Weibull++. For non-repairable systems or components, reliability demonstration tests are used to demonstrate the reliability at a given time with a given confidence level. For repairable systems, users are more interested in demonstrating the MTBF or the number of failures/repairs during a given time period. In RGA 7, a new DRT tool for repairable systems has been designed for this purpose.

To read more, see http://www.weibull.com/hotwire/issue106/hottopics106.htm  Read more...

Reliability Basics
Comparison of Fisher Matrix and Likelihood Ratio Confidence Bound Methods
In Weibull++, there are several ways to calculate reliability confidence bounds for different distributions. The Fisher matrix (FM) method and the likelihood ratio bounds (LRB) method are both used very often. Both methods are derived from the fact that the parameters estimated are computed using the maximum likelihood estimation (MLE) method. However, they are based on different theories. The MLE estimates are based on large sample normal theory, and are easy to compute. However, when there are only a few failures, the large sample normal theory is not very accurate. Thus, the FM bounds interval could be very different from the true values. The LRB method is based on the Chi-Squared distribution assumption. It is generally better than FM bounds when the sample size is small. In this article, we will compare these two methods for different sample sizes using the Weibull distribution.

To read more, see http://www.weibull.com/hotwire/issue106/relbasics106.htm  Read more...

Tool Tips
  • How can I choose what type of Data Sheet to use in RGA 7?
  • What is an easy and affordable way to ensure that I always have the latest version of ReliaSoft’s software?

To read more, see http://www.weibull.com/hotwire/issue106/tooltips106.htm  Read more...

Latest Software Updates
New service releases are now available for and Lambda Predict (SR 3.0.3). To determine the compile revision of the application on your computer, select About from the Help menu. More Software Downloads...
Application Date Created Version
Lambda Predict
Lambda Predict 3 11/16/09 3.0.3
Hot News
* ARS Europe Advance Registration - The 2010 European Applied Reliability Symposium will be held in Berlin, Germany from April 7 - 9, 2010. You can save €100 by registering early! The advance registration deadline is January 29, 2010, so don't wait -- register now at http://www.ARSymposium.org/europe/register_eu.htm. For more information, including the program matrix, please visit http://www.ARSymposium.org/europe/index.htm.
* 56th Annual Reliability & Maintainability Symposium (RAMS) - ReliaSoft Corporation is proud to announce our continued participation in the annual RAMS event. In addition to exhibiting our products, we also will be presenting three tutorials and four papers covering topics such as reliability program planning, FMEAs, reliability estimation and temperature acceleration in reliability prediction. Be sure to stop by our booth to meet our reliability experts, who will provide you with valuable information and a preview of the extensive capabilities of our complete suite of reliability tools including our Web-based XFRACAS application. We look forward to seeing you at the Doubletree Hotel San Jose in California from January 25 - 28, 2010. For an advance program and registration information, please visit http://www.rams.org.
* ARS North America Proposals - The Applied Reliability Symposium is renowned for world-class presentations in the field of reliability and maintainability engineering. Do you have what it takes to garner a coveted presentation slot at ARS? Could you be standing among the Excellent Presentation Award winners at the 2010 event in North America, which will be held from June 15 - 17, 2010 in Reno, Nevada? You will never know unless you submit your presentation proposal by December 14, 2009. Everything you need to know is available for review online at http://www.ARSymposium.org/present.htm. For those who have already submitted their presentation proposals, thank you! The ARS Committee sincerely appreciates your effort and will begin the selection process soon. For those who have yet to submit their proposals, time is running out, so act now!  
Upcoming Public Training Event Calendar
December 2009
December 14 - 18, 2009: RS 540 Reliability and Maintainability Analysis for Repairable Systems in Chennai, India
January 2010
January 6 - 8, 2010: RS 560 Fundamentals of Design for Reliability in Hyderabad, India
February 2010
February 8 - 12, 2010: MSMT Foundations in Berlin, Germany
February 10 - 12, 2010: RS 560 Fundamentals of Design for Reliability in New Delhi, India
February 22 - 26, 2010: MSMT Foundations in Tucson, AZ
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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