In this issue: Issue 109, March 2010
*Hot Topics
*Reliability Basics
*Tool Tips
*Latest Software Updates
*Hot News
*Contribute to HotWire

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Hot Topics
Crow Extended Fleet Analysis
RGA offers two data types that have been designed to analyze data from systems operating in the field: Repairable and Fleet. This example illustrates the use of the Fleet data type. This type of data is intended to be used for analyzing randomly selected systems from the field. The results are returned in terms of total number of fleet failures vs. total fleet operation time (as opposed to the Repairable data type, which returns results in terms of individual system time). The main advantage of the Fleet data type is the ability to apply the Crow Extended model to data obtained from in-service systems that are being used in the field. With this analysis, you can evaluate the improvement (i.e. the "jump" in the MTBF) that could be achieved by rolling out a fix (or set of fixes) for all units operating in the field. In this article we will illustrate this application.

To read more, see http://www.weibull.com/hotwire/issue109/hottopics109.htm  Read more...

Reliability Basics
Unbiasing Parameters in Weibull++
Commonly used methods for parameter estimation, such as the maximum likelihood estimation (MLE) and the least squares estimation (LSE) or rank regression (RR), are known to be biased. This is particularly true with small sample sizes and censored data. Bias correction methods have been studied in the literature. A well known example is the standard deviation obtained using MLE for which it can be shown that an unbiased estimator may be obtained. Weibull++ makes it possible to calculate unbiased parameters for the standard deviation in the Normal distribution, and for beta in the 2-parameter Weibull distribution. In this article, we will discuss the method used in Weibull++ to calculate the unbiased beta estimator for MLE, for both complete and censored data. Unlike the case of the Normal distribution, this is an empirical method obtained via simulation.

To read more, see http://www.weibull.com/hotwire/issue109/relbasics109.htm  Read more...

Tool Tips
  • How can I assign factors to specific columns of a Taguchi orthogonal array in DOE++?
  • What tools are available to help me design a reliability demonstration test?

To read more, see http://www.weibull.com/hotwire/issue109/tooltips109.htm  Read more...

Hot News
* Sneak Preview - With new major version releases of Xfmea and RCM++ on the horizon, we thought you would enjoy a brief glimpse into our plans for Version 5. Although we have included many new features and enhancements, much of our focus has been on improving usability in order to make the power and flexibility of this software more accessible to all users, regardless of experience. The redesigned interfaces are more user-friendly due to better organization of menus, tools, settings and controls, as well as the inclusion of popular features such as drag-and-drop functionality. We've also made it easier to customize reports and FMEA spreadsheets, while providing more visibility for related analyses such as DRBFMs, DVP&Rs and Control Plans. New features include a custom Risk Ranking Utility and Risk Discovery Analysis and an Import Utility that allows you to query and record type up to 3 search terms. More detailed information will appear on ReliaSoft.com once Xfmea 5 and RCM++ 5 are officially released. Please contact us if you would like to be added to our notification list.
* U.S. Military Directives Update - As many of you know, weibull.com is the most comprehensive Web site devoted entirely to the topic of reliability engineering. You may not know, however, that we included a section specifically for U.S. Military directives, handbooks and standards related to reliability practices at http://www.weibull.com/knowledge/milhdbk.htm. For your convenience, we post periodic updates such as the November 2009 memorandum from the Director to DOT&E Staff regarding "Test and Evaluation (T&E) Initiatives." This particular memorandum stresses that Test and Evaluation Strategies (TES) and Test and Evaluation Master Plans (TEMP) for new or restructured programs will not be approved if they lack a reliability growth curve or software failure profile. If you are actively involved with the U.S. Military as an engineer or a supplier, the full memorandum may be of interest to you.
   
Upcoming Public Training Event Calendar
March 2010
March 15 - 19, 2010: MSMT Foundations in Kuala Lumpur, Malaysia
March 16 - 18, 2010: RS 522 Advanced System Reliability / Maintainability Analysis in Tucson, Arizona
March 22 - 23, 2010: RS 490 Standards Based Reliability Prediction in Singapore
March 24 - 26, 2010: RS 522 Advanced System Reliability / Maintainability Analysis in Singapore
April 2010
April 5 - 9, 2010: RS 540 Reliability and Maintainability Analysis for Repairable Systems in Jakarta, Indonesia
April 7 - 9, 2010: International Applied Reliability Symposium in Berlin, Germany
April 19 - 23, 2010: MSMT Foundations in Stockport, United Kingdom
April 19 - 23, 2010: MSMT Foundations in Tucson, Arizona
April 19 - 21, 2010: RS 521 Advanced Accelerated Life Testing Analysis in Bangalore, India
May 2010
May 10 - 14, 2010: MSMT Foundations in Singapore
May 10 - 12, 2010: RS 588 DOE: Experiment Design and Analysis in Warsaw, Poland
May 11 - 13, 2010: RS 511 Application of Reliability Growth Models in Developmental Testing and Fielded Systems in Tucson, Arizona
May 11 - 13, 2010: RS 521 Advanced Accelerated Life Testing Analysis in Tucson, Arizona
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