enerjee » geek out

Audi A3 Radiator Problems

rajat — Thu, 08 Jul 2010 17:33:09 +0000

My 2006 Audi A3 has been leaking coolant for many months now. Usually it had been a slow leak, and I would need to top off the fluids about once a month. This is not standard – in most radiators the anti-freeze should stay level indefinitely.

My problem was that on long road trips, the coolant would disappear at a much higher rate. If I left from Boston at 10am, by the time I hit New Jersey around 3pm, the coolant indicator would be on and the coolant reservoir would be totally empty. This could be very dangerous and cause the engine to overheat, causing permanent damage and more importantly stranding me on the road. That would be a huge pain in the ass.

I’ve been reading around the interwebs and heard nightmare stories – A3′s apparently have a tendency to have leaky head gaskets and / or cracked cylinder heads. It is less than thrilling to have the engine of your 4-year old auto, just off warranty, dismantled and reassembled. The mechanic’s bill would make anyone cry. I was scared for my car.

Well, the resolution was a good one. This radiator was another casualty of I-93 and the shitty job the road crews did to clean up rock chips and asphalt while they resurfaced it last summer. While I worked at LogMeIn, I’d drive up 93, way too fast, on my way to work. For 2-3 months, the road was milled and shaved down, but not repaved. There was an unbelievable amount of debris on the road and my windshield was cracked in 3 places by flying rocks.

Turns out one of the flying rocks destroyed my radiator too.

The radiator. Obvious marks from dried / burnt coolant leaking for a long period of time. It was necessary to remove the radiator to see this damage. Two mechanics looked at it for estimates and couldn’t see the source of the leak.

Point of Impact. Probably a stone chip or bit of flying asphalt.

Wide open for easy access. The radiator is right behind the grille without any protection.

Another casualty of I-93 rocks. I’m going to need a new windshield soon.

Netflix Streaming Error 8156-6003, Silverlight Update

rajat — Tue, 08 Jun 2010 14:32:32 +0000

I’m getting a streaming error “DRM Error” while trying to stream netflix. I watched an episode of Lost when I got home last night, soon after midnight, and it worked fine. What could be causing this error today?

Since everyone knows that Microsoft Silverlight is a piece of crap, it is the immediate culprit. I noticed that a Silverlight update was installed by Microsoft today or last night.

The Update number is KB982926 and it seems to have broken Netflix’s Streaming capabilities. It contained Silverlight Version 4.

FIX:
1. Go to Windows Update Settings and change it from “Automatically install updates” to “Download updates and ask me when to install” (otherwise silverlight will reinstall itself again)
2. Close your web browser
3. Go to Control Panel -> Uninstall a program -> Remove Silverlight
4. Go to netflix.com and start streaming a movie. It will prompt you to go to microsoft’s site and install Silverlight Version 3.
5. Restart your browser and it should work. Just worked for me on Windows 7.

I use ad revenue to pay for my hosting. So if you found my tip useful please …

Concept Map in Processing Library

rajat — Wed, 05 May 2010 17:40:04 +0000

This code makes a Concept Map with the Processing library / Java. Processing library makes it easy and quick to make graphical representations and animations, among its many features.

    /**
     * setup is called implicitly by the library when rdraw is called
     * it sets the size, drawing method, then in this case draws the graph
     */
    public void setup() {
      size(boxSize,boxSize);
      smooth();
      drawGraph();
     }
    /**
     * Draws the graph. req and neighbors must have been
     * previously set through the construtor or the setters
     */
    public void drawGraph()
    {     
        int halfBox= 150;
        //processing uses radians, not degrees
        float angle = 2*PI / neighbors.size();
        for(int i = 0; i < neighbors.size(); i++)
        {
            float cur_angle = i*angle;
            String s = neighbors.get(i);
   
            //calculate an even dispersal around the central objet
            //it depends on how many objects are in your list
            float xpos = halfBox*cos(cur_angle)+center;
            float ypos = halfBox*sin(cur_angle)+center;
       
            //color=black, draw a line to new item
            stroke(0);
            line(center,center, xpos,ypos);
            //put the item last, on top of the lines
            drawCircle(xpos, ypos, s);
        }
        //put the item last, on top of the lines
        drawCircle(center,center,result);
    }

    /**
     * draws a circle with specified text at (x,y)
     * @param x the x position of where the circle will go
     * @param y the y position of where the circle will go
     * @param word the word that will go in the middle of the circle
     */
    public void drawCircle(float x, float y, String word)
    {
        fill(255);
        ellipse(x,y,word.length()*10, 40);
        fill(0, 102, 153);
        textAlign(CENTER);
        text(word,x,y);
    }

/**
     * Makes a graph with req in the middle, surrounded
     * by neighbors n. calls the library's super, Papplet.main
     */
    public void rdraw(String req, ArrayList n)
    {
        result = req;
        neighbors = n;
     
        PApplet.main(new String[] { "--bgcolor=#ECE9D8", "BrainH.client.ConceptMap" });
    }

Compete Source here [ConceptMap.java].

public class ConceptMap extends PApplet {

/**
*
*/
private static final long serialVersionUID = 690002409249816629L;
private int boxSize = 500;
private int center = boxSize / 2;
private static String result = “”;
private static ArrayList neighbors = null;

public ConceptMap() {};
public ConceptMap(String req, ArrayList n)
{
result = req;
neighbors = n;
}

/**
* setup is called implicitly by the library when rdraw is called
* it sets the size, drawing method, then in this case draws the graph
*/
public void setup() {
size(boxSize,boxSize);
smooth();
drawGraph();
}

public void setNeighbors(ArrayList arg)
{
neighbors = arg;
}

public void setObject(String req)
{
result = req;
}

/**
* Draws the graph. req and neighbors must have been
* previously set through the construtor or the setters
*/
public void drawGraph()
{
int halfBox= 150;
//processing uses radians, not degrees
float angle = 2*PI / neighbors.size();
for(int i = 0; i < neighbors.size(); i++)
{
float cur_angle = i*angle;
String s = neighbors.get(i);

//calculate an even dispersal around the central objet
//it depends on how many objects are in your list
float xpos = halfBox*cos(cur_angle)+center;
float ypos = halfBox*sin(cur_angle)+center;

//color=black, draw a line to new item
stroke(0);
line(center,center, xpos,ypos);
//put the item last, on top of the lines
drawCircle(xpos, ypos, s);
}
//put the item last, on top of the lines
drawCircle(center,center,result);
}

/**
* draws a circle with specified text at (x,y)
* @param x the x position of where the circle will go
* @param y the y position of where the circle will go
* @param word the word that will go in the middle of the circle
*/
public void drawCircle(float x, float y, String word)
{
fill(255);
ellipse(x,y,word.length()*10, 40);
fill(0, 102, 153);
textAlign(CENTER);
text(word,x,y);
}

/**
* Makes a graph with req in the middle, surrounded
* by neighbors n. calls the library’s super, Papplet.main
*/
public void rdraw(String req, ArrayList n)
{
result = req;
neighbors = n;

PApplet.main(new String[] { “–bgcolor=#ECE9D8″, “BrainH.client.ConceptMap” });
}
}

An Amazing feat of Engineering

rajat — Fri, 09 Apr 2010 18:21:41 +0000

Who says geekiness can’t be cool? Even the biggest Luddite should appreciate this.

A Japanese company, Daishin, made this video to commemorate their 50th anniversary. Their milling machine spins on 5 axis. I can’t get over the way the platform and drill head move in synchrony in this video.

Machining Aluminum: How a large block of aluminum is “milled” or sculpted into a finely detailed part. Usually for a mechanical part. You wouldn’t machine a fork or tin can, but there is no other way to make a part for an aircraft or automobile engine.

Installing Ruby and Rails 1.9.1 on Ubuntu 9.x

rajat — Fri, 05 Feb 2010 23:53:18 +0000

One would think that installing Ruby & Rails on Ubuntu 9.X would be cake, right? WRONG. It is a lot of unexpected work and package additions. It no longer works “out of the box”.

Important Note: Install as many packages as you can before trying to run your Rails project. Once you type “ruby script/server” , the weaknesses of your configuration will be exposed, and who knows how the system will behave. Fill in the missing packages before this happens.

From the beginning

Your best bet for getting started is to use Synaptics Package Manager to install this package that supposedly contains everything you need:
ruby1.9.1-full
While you are at it, get the following dependencies that WILL come back to haunt you later:
rubygems1.9.1
libopenssl-ruby1.9.1
libruby1.9.1
sqlite3 (omit if you’re using MySQL)
libsqlite3-dev (omit if you’re using MySQL)

Accept all of the dependencies that Synaptics asks you for. More is better!

Symbolic Links

Do you want to type “ruby1.9.1″ each time? Nah i don’t think so. Make some symbolic links to help you out.

sudo ln -s /usr/bin/ruby1.9.1 /usr/bin/ruby
sudo ln -s /usr/bin/gem1.9.1 /usr/bin/gem
sudo ln -s /usr/bin/rake1.9.1 /usr/bin/rake

ln makes symbolic links. Check out the man page on it. You can delete the symbolic links when Ruby1.9.2 or whatever comes out.

Rails

Why doesn’t this come standard? Boggles my mind.

sudo gem install rails

Sqlite3

Status: 500 Internal Server Error
no such file to load -- sqlite3

Use Synaptics and install : libsqlite3-dev to get sqlite3.h header file

Then:

sudo gem install sqlite3-ruby

Scrapers

If you use hpricot or any kind of scraper, use Synaptics package manager to get:

libxml2
libxml2-dev
libxslt1-dev

sudo gem install hpricot
sudo gem install mechanize

Random Stuff

Problem: NameError (uninitialized constant ApplicationController)
Fix: sudo rake rails:update

Problem: syntax error, unexpected ':', expecting keyword_then or ',' or ';' or '\n' when "rated" : @movies = Movie.paginate(:al...
Fix: In Ruby 1.9, colons in a case statement are disallowed. Replace them with a "then" statement.

Turns out that the new rails renames app/controllers/application.rb to application_controller.rb. This cute rake task will take care of it for you.

sudo gem install hpricot

Can’t compile the example WordCount.java (Hadoop)

rajat — Wed, 02 Dec 2009 05:34:41 +0000

http://mail-archives.apache.org/mod_mbox/hadoop-common-user/200907.mbox/%3Cd6d7c4410907201717t672e4caet3f369d7e4327ff7b@mail.gmail.com%3E

Seen this?

Rajat@rtde ~/java
$ javac -classpath /home/Rajat/hadoop-0.20.1/hadoop-0.20.1-core.jar -d
wordcount_classes WordCount.java

WordCount.java:5: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.Path;

WordCount.java:6: package org.apache.hadoop.conf does not exist
import org.apache.hadoop.conf.*;
^
WordCount.java:7: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.*;
^
WordCount.java:8: package org.apache.hadoop.mapred does not exist
import org.apache.hadoop.mapred.*;
^
WordCount.java:9: package org.apache.hadoop.util does not exist
import org.apache.hadoop.util.*;

And running CygWin on Windows? Tried everything for your classpath
huh? Try this:

$ javac -verbose -classpath C:\\cygwin\\home\\Rajat\\hadoop-0.20.1\\hadoop-0.20.1-core.jar -d wordcount_classes WordCount.java

(Change your cygwin path, obviously)

Use the -verbose flag to show the entire class search path.

Aircrack NG on iwl3945

rajat — Wed, 25 Nov 2009 15:34:32 +0000

The iwl3945 would not go into monitor mode as easily as some of the
documentation says.

To get this to work, I had to go through a peculiar set of steps.
Notice the changing argument, wlan0 or wifi0.

1. airmon-ng stop wlan0
( will say “monitor mode disabled)

2. airmon-ng stop wifi0
(will say nothing much)

3. airmon-ng start wlan0
(now it agrees to go into monitor mode:
(Monitor mode enabled on mon0)

Keep Spiders and Bots from clicking links & pushing buttons (Ruby)

rajat — Wed, 18 Nov 2009 03:38:50 +0000

Here is a useful function to detect, in your controller, when a bot or web spider is clicking your links and pushing your buttons.Place this in helpers/my_helper.rb (use your own controller name obviously).

def MyHelper.is_bot?(request)
request.user_agent.downcase =~ /bot|slurp|spider|crawl/
end

Simple enough, but useful.

In my case, on a site i’ve been building, www.movie-cat.tv, the googlebot was coming through and marking all movies as “unavailable” through a simple crawl. If the bot is detected, the controller should not mark the movie unavailable, instead return before performing some action. This solved it.

GoogleBot, MSNBot, Yahoo Slurp, BaiduSpider. Modify the regex by adding any other bots you want to exclude, and separating them with a pipe “|”.

ScrubyT traverse_for_match: undefined method each for nil:NilClass

rajat — Sun, 20 Sep 2009 21:43:56 +0000

Using ScrubyT, a Ruby on Rails plugin, on a Linux system such as my CentOS 5 VPS, you can get an error message and stack trace like this:

/usr/lib/ruby/gems/1.8/gems/scrubyt-0.4.06/lib/scrubyt/utils/shared_utils.rb:43:in `traverse_for_match’: undefined method `each’ for nil:NilClass (NoMethodError)

If you see this, go to shared_utils.rb in the path above, and change this block:

node.children.each { |child| traverse_for_m….

into this:

if node.children
node.children.each { |child| traverse_for_m….
end

Thanks to Deginzabi who wrote about it in Japanese. This article is a translation of what he said. Hope this makes the next ScrubyT release! It is a great project.

Google Talk – Invisible Mode

rajat — Sun, 30 Aug 2009 16:52:47 +0000

Did you know that you can use “Invisible Mode” in the Google Talk app? This is not the web application, but the genuine standalone Google Talk app. You don’t have to use the GTalk applet that is embedded in Gmail any longer, and can avoid cyberstalkers with class and sophistication!

Here is the link to the version of GTalk you’re interested in – Google Talk Labs Edition:

http://www.google.com/talk/labsedition/index.html

I would recommend uninstalling the ordinary version of Gtalk first, otherwise the two will be installed side by side and become an annoyance.