tim

CY2014 Quarter 1 Financial Review

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Chrissy and I review our spending on a quarterly basis. Updating every 90 days isn’t too long to correct mistakes and remember purchases, but it also allows for the busy multi-week sprints that life presents us. While we have used every financial management program available, I’ve found the most straightforward and flexible solution is to … Read more

Fun with Bessel Functions

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Well, I certainly forget things faster than I learn them. Today is a quick review of Bessel functions and their applications to signal processing. The Bessel functions appear in lots of situations (think wave propagation and static potentials), particularly those that involve cylindrical symmetry. While special types of what would later be known as Bessel … Read more

Excel Sorting and Grouping

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I had two tables downloaded from Amazon: Items Order Date Order ID Title Category 1/26/14 102-4214073-2201835 Everyday Paleo Family Cookbook 1/13/14 115-8766132-0234619 Awesome Book A 1/13/14 115-8766132-0234619 Awesome Book B and Orders Order Date Order ID Subtotal 1/6/14 102-6956821-1091413 $43.20 1/13/14 115-8766130-0234619 $19.42 1/16/14 109-8688911-2954602 $25.86 I’m building our Q1 2014 taxes and needed rows … Read more

Sampling Exploration

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I needed to review the Nyquist–Shannon sampling theorem. The coolest thing about Nyquist is that it expresses the sample-rate in terms of the function’s bandwidth and leads to a formula for the mathematically ideal interpolation algorithm. What is sampling? Sampling is nothing more than converting a signal into a numeric sequence. Shannon states: If a … Read more

Practical Cutting Stock Problem

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Warning. This post is for an audience of close to zero. My technical friends will find this pretty basic, and my non-technical friends will find this too technical. Welcome to the middle space that I occupy between these two worlds. I wanted to build this series of retaining walls to replace the overgrown ivy and … Read more

Consistency, Focus and Grace

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“My commitment must be to truth, not to consistency.” — Ghandi Then Jesus said to his host, “When you give a luncheon or dinner, do not invite your friends, your brothers or sisters, your relatives, or your rich neighbors; if you do, they may invite you back and so you will be repaid. But when … Read more

World Vision and the Culture Wars

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I, for one, am tired of arguing. I’m tired of trying to defend evangelicalism when its leaders behave indefensibly. Is there a problem with hypocrisy in the modern church? Yes, just as there was in the ancient, medieval and renaissance churches. Fortunately, Christian doctrine and practice accounts for the fact that all of the churches … Read more

Analysis of The Boohers’ Energy Usage

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Using my Vera Lite and Z-wave home energy monitor I was able to record a week’s worth of electricity consumption at 30 second intervals. I was surprised how hard it was to use the data to do anything, but amazed with how my behavior changed when I knew our household consumption was being tracked. Again, if you want to improve something, I feel it needs a tracking system. Electricity usage is a nice case study for this, because it has a clean metric (wattage) over a time series.

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