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Showing posts from July, 2010

Eating your own dog food in the 1960s

It's common in the software industry to hear the phrase "Eat your own dog food". It's so common that Wikipedia has a page dedicated to the phrase. The idea is that a software developer should also be a user of the software they are developing. By analogy someone making dog food should make it good enough that they'll eat it themselves.

The phrase has been around since at least the 1980s, but I recently came across a much earlier expression of the same idea. And this came from one of the X-15 test pilots: Milton Thompson.

Some models of the X-15 contained a device that mixed the aircraft controls of the X-15 with the rocket controls. Since the X-15 would fly like a plane and a spacecraft it had both conventional airfoils and thrusters. These were originally controlled by different joysticks. The mixing device was the MH-96 and enabled the pilot to fly the X-15 in the atmosphere or in space using a single joystick.

But that meant that the MH-96 was controlling …

The bandwidth of a fully laden 747

Never underestimate the speed of shipping physical stuff when you want to move large amounts of data. The Internet is actually horribly slow even at 'high' speeds. That's why Amazon Web Services offers an Import/Export service that involves shipping physical disks around.

Back in 1999 I wrote an article for The Guardian explaining latency and bandwidth for modem users. In it I used a jet plane full of people flying across the Atlantic to illustrate the difference.

The analogy still works today, and brings me to the farcical question: what's the bandwidth of a fully laden 747?

Assuming I fill it with DAT 320 cartridges, each of which can contain 160GB of uncompressed data and each of which weigh about 50g then I can fit about 2.8m cartridges in the plane (a single 747 can lift 140 tonnes). That's about 427 PB of storage in the plane. (I'm not sure that many cartridges will actually fit inside the 747, but you get the idea).

Now assume it flies from San Francisco…

Monte Carlo simulation of One Banana, Two Banana to develop a card counting strategy

The children's game One Banana, Two Banana is a high stakes game of probability theory in action. Or something like that. Actually, it's a fun game where you have to take probability into account when deciding what to do.

Conceptually, the game is simple. There are 54 cards of five types. Three of the card types have bananas on them (one, two or three bananas), one card type has a banana skin on it and one card type has a swamp on it. All the cards are placed face down on the table and shuffled about. Each player takes turns at turning over as many cards as they want.

The total distance they move on the board (winning is a simple first past the post system) is the sum of the number of bananas on the banana cards. But if they pick a banana skin card then they stop picking cards and must reverse direction by the sum of the number of bananas on the banana cards. The swamp card simply stops a turn without a penalty.


There are six banana skin cards to start with and as they ar…

GAGA-1: Some initial investigations

I've been investigating bits and bobs to go into GAGA-1 and have run one freeze test.

1. Components

I've now got the Telit GM862 module up and running with Arduino Duemilanove and have uploaded a simple Python script that SMSes me the device's location once a minute. The module is on the right in the picture and a SparkFun board for it is on the left.


Here's an example SMS received on my phone from the device giving latitude and longitude and GPS status. This format is by no means final, it's just a test.


I've also started working with the Trimble Lassen IQ module which is tiny:


It will eventually be interfaced directly to the Arduino which will connect to the radio to send down telemetry.

2. Freeze test

In my first post on the subject, I said that I'd be doing a freeze test of everything. My first test was to build a simple temperature sensor using an LM35 and then put the Arduino in my home freezer and allow its temperature to drop to -18C for a hour. This t…

The Geek Atlas Companion

The Geek Atlas has been out for a year now, and there's been an iPhone version for a while.

But now there's a special companion application for the book: The Geek Atlas Companion. O'Reilly developed this as a counterpart to the book.


My favorite part of the application is the ability to find places from the book that are near you. The application has all 128 places in it with their coordinates (just like the book) and using the iPhone's GPS it can give you a list of places near you. Each place has a small summary of what you'll see there, but not the complete book text. The application is designed as an add on and not a replacement for the book itself.

A fun part that O'Reilly developed is a quiz based on the book. Multiple choice questions lead you through some of the science that's covered in The Geek Atlas.

Finally, there's a strong community component where users are encouraged to upload their photographs of locations in the book. The applicatio…

BallastHalo 5 launch afternoon out

The early bird truly catches the worm. I woke up at 0530 this morning and couldn't go back to sleep. After dealing with email etc. I was able to get to the Apple store to see a Genius, browse around in Maplin, go to the Post Office and be back home by 1000. So, then I started browsing around a bit for a project I'm slowly working on: sending a balloon up into the stratosphere to photograph the Earth and space (more on that in a separate blog post).

I wandered over to the UK High Altitude Society web site and idly clicked on Current Launch. I had to read the date 10/07/10 about three times before I realized that it was today, that I could make it to Cambridge for the launch if I moved it.

I quickly Twittered to James Coxon to see if I'd be welcome. I was. I grabbed the Jack Pack and stuffed it with journey essentials: iPhone, Kindle, Oyster Card, Camera and Power Monkey and raced to Cambridge via Kings Cross.

I arrived with enough time to sit down with Nathan Chong of Ne…

GAGA-1

In April 1961, Yuri Gagarin became the first human into outer space and the first to orbit the Earth. In honor of Gagarin I'm planning to launch my own 'space' mission which I'm code naming: GAGA-1.

The code name serves a triple purpose: it sounds funny, it's the first four letters of Gagarin's name and it stands for "Geek Atlas Goes Airborne". None of the places in The Geek Atlas are quite as high as GAGA-1 will travel; I'll have to come up with a mission patch that includes The Geek Atlas in some way.

My mission won't be quite as high as Gagarin's: I plan to launch a helium-filled balloon into the stratosphere in attempt to photograph and film the curvature of the Earth with the blackness of space visible. Also unlike Gagarin, others have gone before me: it's quite possible to launch a 'weather' balloon carrying a payload with cameras and take photographs at an altitude of 30km or greater. See, for example, this post about …

The CCE Review report

Today, the Independent Climate Change Email Review report was issued. As a bit of background I'll point you to some of my old blog posts on this:

1. Met Office confirms that the station errors in CRUTEM3 are incorrectly calculated

2. Something a bit confusing from UEA/CRU

3. Something odd in CRUTEM3 station errors

4. New version of CRUTEM3 and HADCRUT3

5. Well, I was right about one thing

6. Bugs in the software flash the message "Something's out there"

7. Whoops. There's a third bug in that code

And here's what one of the people involved in the report wrote:

First, climategate reveals the urgent demand by a new breed of citizen-scientist for access to the raw data scientists use to do their work. Simply accepting a scientist's assurance that data are accurate and reliable is no longer enough. Scientists will have to make their data available for independent audit.

Second, climategate shows that science must change its idea of accountability. Traditionally, scie…

Bayes, Bletchley, JN-25 and a 'modern' optimization

In the current edition (June 2010) of significance (the magazine of the Royal Statistical Society) there's an article titled Edward Simpson: Bayes at Bletchley Park. Simpson is the man behind Simpson's Paradox (which, if you have not heard of it, you should immediately go and read about because it's... weird). He also worked at Bletchley Park during the Second World War.

I found the article fascinating for three reasons: it's about Bletchley Park, it's about Bayes Theorem (which I've spent quite a lot of time dealing with) and it highlights an optimization that was done to enable WRENs to work faster, yet is still in use today.

The article talks about life at Bletchley Park, and the breaking of two codes: Enigma and the Japanese JN-25. So much has been written about Enigma that I have little more to say about it, but JN-25 is a different matter. Its breaking involved a bit of Bayes and ended up helping the Allied victory at the Battle of Midway.

JN-25

This Japa…