Accendo Reliability

Your Reliability Engineering Professional Development Site

Home » Articles » Page 203

Articles

Find all articles across all article series listed in reverse chronological order.

by Leave a Comment

McNemar Test

McNemar Test

The McNemar test is a nonparametric statistical test to compare dichotomous (unique) results of paired data.

If you are comparing survey results (favorable/unfavorable) for a group of potential customers given two ad campaigns, or evaluating the performance of two vendors in a set of prototype units, or determining if a maintenance procedure is effective for a set of equipment, this test permits the detection of changes.

The McNemar test is similar to the χ2 test. The McNemar only works with a two by two table, where the χ2 test works with larger tables. The χ2 test is checking for independence, while the McNemar test is looking for consistency in results.

Let’s examine an example where a group of people are surveyed about a prototype design, before and after a presentation. [Read more…]

by 2 Comments

Engineering Manager – The Sasquatch of Leadership?

Engineering Manager – The Sasquatch of Leadership?

“[They] aren’t just hard to find — they don’t exist”

Think this was written about the elusive Sasquatch?  Loch Ness monster, maybe?  What about the abominable snowman?

Nope, nope, and nope.  This was referring to good engineering managers.

In his opinion piece, Juan Pablo Dellarroquelle argues that engineers that are good at their jobs have little incentive to move into a managerial role because they are already influential leaders in an individual contributor role.

Alternatively, he argues, engineers who are weak technically are promoted to managers because of their organizational skills.

While this may be the case in some circumstances, in general – I disagree.   [Read more…]

by Leave a Comment

A Scalable Model for Lean Product Development

A Scalable Model for Lean Product Development

In my previous article we established the lean product development goal statement as:

Develop products that maximize customer value and minimize product cost, in the least amount of time, and at the least amount of product development cost.

We then derived high-level objectives as follows:

  • Better understand the customer (maximize customer value)
  • Do the right projects (product, project and portfolio value analysis)
  • Do projects right (minimize redesigns, waste and rework)
  • Level load the organization (minimize bottlenecks and resource constraints)
  • Create and re-use artifacts (standardize and sustain best practices)

[Read more…]

by Leave a Comment

Process Capability – Article Links

Process Capability – Article Links

Process Capability Articles

This post provides a list of my process capability articles, a short description and a link. The goal is to make it easy for the reader to locate any of the articles. It is recommended to read these articles in the order presented.  This post will be updated when additional posts are written on the Process Capability topic.

[Read more…]

by Leave a Comment

Old School Team Building

Old School Team Building

Old School Team Building

I’m facilitating an RCM Analysis this week in a second-floor conference room that overlooks a company courtyard complete with manicured landscaping, picnic tables, park benches and walking path complete with distance markers. While this park like setting has been mostly empty the first few days this week today there is a group of 30 people milling around. Some small groups of 2 or 3 are clustered together talking and most everyone is checking out their smart phone for various unknown reasons. I can’t help but wonder what is going on so I ask the team I’m working with why so many people are in the courtyard. [Read more…]

by Leave a Comment

Is Your Organization’s Planning Brittle?

Is Your Organization’s Planning Brittle?

Guest Post by Geary Sikich (first posted on CERM ® RISK INSIGHTS – reposted here with permission)

Is Your Organization’s Planning Brittle?

Good intentions do not make for the creation of a robust/resilient organization.  Business Continuity plans, Disaster Recovery plans, Emergency Response plans, etc., that are standalone documents generally reflect good intentions – whether to meet regulatory requirements or to address governance.  I would have to say that this should be a wake-up call for executives in all industries.  We live in a complex and interdependent world.  Complex systems are full of interdependencies that are hard to detect.  The result is nonlinearity in responses to events, especially random events/shocks. 

The odds of rare events are simply not computable.  Model error swells when it comes to small probabilities.  The rarer the event; the less tractable, and the less we know about how frequent its occurrence. [Read more…]

by 2 Comments

Heat Exchanger Design and Use

Heat Exchanger Design and Use

What readers will learn from this article.

  • Basic theory of heat exchange across walls.
  • Necessary properties of fluids to make heat exchangers work.
  • Protecting and checking heat exchangers against corrosion.
  • Issues with using shell and tube heat exchangers.
  • Issues with using plate heat exchangers.

This article introduces readers to heat transfer in heat exchangers. It explains the concepts of temperature gradients across walls and parallel- current and counter-current flows. Both shell-and-tube and plate heat exchanges are discussed along with their common operational problems and remedies.

Shell-and-tube and plate heat exchangers (HXCH’s) are recuperative type devices, meaning that flowing fluids exchange heat through a dividing wall. The exchange of heat occurs from the hotter liquid to the cooler one. The hotter liquid is at a higher energy level than the colder liquid and the energy flows from hot to cold in an attempt to reach a steady equilibrium state at an intermediate temperature. [Read more…]

by 10 Comments

FMEA Q and A – Special Characteristics in Process FMEA

FMEA Q and A – Special Characteristics in Process FMEA

FMEA Q and A

Ponder this question: Let’s say you are an OEM and assemble parts made by various suppliers. When performing your Process FMEA, do you consider special characteristics for components in your Process FMEA? This question is discussed and answered in this edition of FMEA Q and A.

“The key to wisdom is this – constant and frequent questioning, for by doubting we are led to question, by questioning we arrive at the truth.”
Peter Abelard

[Read more…]

by 2 Comments

Process Capability Analysis IV – Improve the Process

Process Capability Analysis IV – Improve the Process

In the article Process Capability I – Overview and Indices, the main process performance indices were defined. In the article Process Capability Analysis II – Estimating Percent Defective, ways to calculate the percent defective were introduced.

Next, a way to estimate estimate the percent defective was discussed in Process Capability III – Cp vs Percent Defective. The data showed the process had a  Cp ~0.46, so even if centered, a high percentage of parts would be non-conforming! In industry, it is common to see a Cp of about 1. The paradigm is that if the process range is just contained within the tolerance range, it is satisfactory.  Such processes are marginally capable. A process mean shift away from the target or an increase in variation significantly increases the number of non-conforming parts.  Process Capability needs to be increased. At a minimum, Cp should be greater than 1.33, but larger is better.

There are two approaches to improving process capability. One is to center the process and the other is to reduce variation. Both need to be accomplished.

[Read more…]

by Leave a Comment

Reliability and Availability Modeling in Practice

Reliability and Availability Modeling in Practice

By Kishor S. Trivedi

Kishor forward the link to the recording to me and suggest it may of interest to the Accendo Reliability community. I agree. He does a great job discussing the topic and a clear and practical manner.

The video abstract is:

IEEE Life Fellow and Hudson Chair in the Department of Electrical and Computer Engineering at Duke University Prof. Kishor S. Trivedi visited Alibaba’s Hangzhou campus on Dec. 8th and talked about technical systems’ reliability and availability assurance methods based on probabilistic models. [Read more…]

by Leave a Comment

The 6 Things Every Asset Management Strategy Needs to Be Successful

The 6 Things Every Asset Management Strategy Needs to Be Successful

I want my customers to be successful, every one of them. Yet there are times I can see the writing on the wall and I know as hard as I might try to show them a clear path to what it takes to be successful they have their own plan. Some of them are so complex that people become confused just trying to make sense of them, and others get so hung up in the minutiae of even the simplest of steps like listing a 3 part failure mode they will word-smith themselves to a point where folks just give up. I find myself asking “why do people have to make what is really so simple into something that appears to be complex?” [Read more…]