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Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

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Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

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Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

Last 100 entries

Sentidos Comunes (Chilean Online Magazine); Hilary Mantel: The Assassination of Margaret Thatcher - August 6th 1983; NSA Interceptng Gmail During Delivery; General IIR Filters; What's happening with Scala?; Interesting (But Largely Illegible) Typeface; Retiring Essentialism; Poorest in UK, Poorest in N Europe; I Want To Be A Redneck!; Reverse Racism; The Lost Art Of Nomography; IBM Data Center (Photo); Interesting Account Of Gamma Hack; The Most Interesting Audiophile In The World; How did the first world war actually end?; Ky - Restaurant Santiago; The Black Dork Lives!; The UN Requires Unaninmous Decisions; LPIR - Steganography in Practice; How I Am 6; Clear Explanation of Verizon / Level 3 / Netflix; Teenage Girls; Formalising NSA Attacks; Switching Brakes (Tektro Hydraulic); Naim NAP 100 (Power Amp); AKG 550 First Impressions; Facebook manipulates emotions (no really); Map Reduce "No Longer Used" At Google; Removing RAID metadata; New Bike (Good Bike Shop, Santiago Chile); Removing APE Tags in Linux; Compiling Python 3.0 With GCC 4.8; Maven is Amazing; Generating Docs from a GitHub Wiki; Modular Shelves; Bash Best Practices; Good Emergency Gasfiter (Santiago, Chile); Readings in Recent Architecture; Roger Casement; Integrated Information Theory (Or Not); Possibly undefined macro AC_ENABLE_SHARED; Update on Charges; Sunburst Visualisation; Spectral Embeddings (Distances -> Coordinates); Introduction to Causality; Filtering To Help Colour-Blindness; ASUS 1015E-DS02 Too; Ready Player One; Writing Clear, Fast Julia Code; List of LatAm Novels; Running (for women); Building a Jenkins Plugin and a Jar (for Command Line use); Headphone Test Recordings; Causal Consistency; The Quest for Randomness; Chat Wars; Real-life Financial Co Without ACID Database...; Flexible Muscle-Based Locomotion for Bipedal Creatures; SQL Performance Explained; The Little Manual of API Design; Multiple Word Sizes; CRC - Next Steps; FizzBuzz; Update on CRCs; Decent Links / Discussion Community; Automated Reasoning About LLVM Optimizations and Undefined Behavior; A Painless Guide To CRC Error Detection Algorithms; Tests in Julia; Dave Eggers: what's so funny about peace, love and Starship?; Cello - High Level C Programming; autoreconf needs tar; Will Self Goes To Heathrow; Top 5 BioInformatics Papers; Vasovagal Response; Good Food in Vina; Chilean Drug Criminals Use Subsitution Cipher; Adrenaline; Stiglitz on the Impact of Technology; Why Not; How I Am 5; Lenovo X240 OpenSuse 13.1; NSA and GCHQ - Psychological Trolls; Finite Fields in Julia (Defining Your Own Number Type); Julian Assange; Starting Qemu on OpenSuse; Noisy GAs/TMs; Venezuela; Reinstalling GRUB with EFI; Instructions For Disabling KDE Indexing; Evolving Speakers; Changing Salt Size in Simple Crypt 3.0.0; Logarithmic Map (Moved); More Info; Words Found in Voynich Manuscript; An Inventory Of 3D Space-Filling Curves; Foxes Using Magnetic Fields To Hunt; 5 Rounds RC5 No Rotation; JP Morgan and Madoff; Ori - Secure, Distributed File System; Physical Unclonable Functions (PUFs); Prejudice on Reddit

© 2006-2013 Andrew Cooke (site) / post authors (content).

Concrete

From: "andrew cooke" <andrew@...>

Date: Thu, 6 Jan 2005 15:20:18 -0300 (CLST)

Nice article about concrete -
http://www.sciencenews.org/articles/20050101/bob9.asp

The translucent stuff is super-cool.  We're waiting for a couple of
concrete coffee tables to be made for our living room.  They're not
translucent, unfortunately, but still pretty cool.  The legs and "support"
are made of iron; on top rests a concrete slab, cast in two colours - a
dark inky centre that "leaks" out into a white surround.  Looks more like
plastic than concrete.

A couple of things that articles doesn't make clear.  First, basic
concrete is only strong under compression, not tension.  Just like stone. 
Which is why stone buildings are built the way they are, with arches to
transmit the load through the structure.  Reinforced concrete includes
steel rods to take the tensile stresses, but these stretch under load and
so put an upper limit on the strain (if they stretch too much the concrete
cracks open, water can enter, and things corrode).  Hence the fibres in
Ductal, as described in the article, which replace the steel rods.

The fibres are important for another reason too - a crack grows at the
tip, where stresses are concentrated.  When a crack meets a fibre that is
lying across its path, the stresses are dispersed significantly.  This
stops/slows the growth of the crack, making the material safer.  For
similar reasons sharp corners are avoided in steel structures (the sharp
corner acts as a crack).

One last thing omitted - titanium dioxide is also a common white pigment. 
So the "self cleaning" concrete doesn't look shiny and white just because
it's extra-clean, but also because it has white colouring...

From BoingBoing -
http://www.boingboing.net/2005/01/06/nextgeneration_concr.html

(Chilean concrete tables from these people -
http://www.nuevodiseno.cl/ndweb_publi_gatica.htm - although they seem to
have just removed any info from their web site...)

Andrew

PS I'm going to try adding more comments to my posts if I have the time
and something useful to say, because I've realised that otehrs may not
realise why I think things are interesting.  I'm also looking at putting
these posts on a blog.

-- 
` __ _ __ ___  ___| |_____   work web site: http://www.ctio.noao.edu/~andrew
 / _` / _/ _ \/ _ \ / / -_)  personal web site: http://www.acooke.org
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