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Archive for July, 2008

Half Clutch

July 17th, 2008 No comments

A motorcycle rider’s attitude could be easily
guessed by checking the clutch setting in his motorbike. There are
generally two modes of clutch setting, a half clutch, a full clutch.

To
brush up, clutch is a device that controls the amount of power
transferred from the engine to the rear wheel. Generally clutch device
is made of multiple discs called wet plates
and power is transmitted across these plates by friction. The clutch
lever on the left hand side controls the amount of friction and hence
the power transmitted. When one fully pulls the lever, the clutch
plates move away from eachother and no power transmitted. On the other
hand, when the clutch lever is released fully, maximum friction is
available amidst the plates and maximum power transfer. The magic is
how good one is, in handling the clutch to get the maximum out of the
bike, be it 100cc or 1500cc.

Half clutch is a
setting, where a full pull of the clutch lever does not pull the clutch
plates far away. So effectively, the operating range of the clutch
lever is so small. Even when the lever is released a little, one can
see the rear wheel starts rolling.

If you check
the bikes of boys vrrooomming in the signals like rockets, they would
have half clutch or even smaller. Boys with half clutch have a fast and
furious attitude. They need everything on their plate faster. These
guys cannot wait for anyone. These guys are performers given
opportunity. These boys are quick witted and even some of them are
impulsive too.

On the other hand, the full
clutch boys are patient movers. They take their time to do things.
These guys are steady and focussed. If you take a statistics across age
groups, full clutch setting would be opted by a lot of middle aged men,
who are good in decision making, logical thinking. These boys can wait
for their best catch. It is pretty difficult to make these boys angry.

With
respect of biking, half clutch boys outperform full clutch boys
significantly. The reason is full clutch will not let the bike to
perform to its fullest. One should not forget the half clutch ruins the
clutch plates and engine gears faster.

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Getting roughly 5% waiver in Paying LIC Premiums

July 17th, 2008 No comments

Do you have an LIC policy ? I guess you
have atleast a couple of them. What is your payment frequency ? Is it
quarterly or half-yearly ? Do you know if you pay annual premiums, you
stand to get 3% discount on the premium amount ? There is more to it.
If you have an RD for the raising the funds to insurance premium, you
would an interest of 5-6% per year ( equivalent to 2.5% on FD for that
amount ). So effectively you stand to get a waiver of more than 5% on
the total premium paid every year.

Let’s have an example:

Regular
Insurance Premium: 12000/pa
Frequency: quarterly ( 3000×4 ) = 12000/pa
Discount: 0
Effective payment: 12000-0 = 12000/pa

Stylish
Insurance Premium: 12000/pa
Frequency: annual ( 12000×1 ) = 12000/pa
Discount: 3% = 12000*3% = 360/pa
RD: 1000 pm = 1000×12 pa = 12000pa
Interest: 6% recurring ( 2.5% effective pa )
Interest Amount Accured = 12000*2.5% = 300 pa
Effective Payment = 12000 – ( 360 + 300 ) = 11340 pa.

Won’t you be happy to save few extra Rupees ??

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Sweet Summation Vector

July 17th, 2008 No comments

The popular way to represent a Text Document in vector space is by the summation vector (resultant vector) of all the (meaningful) keywords that formed the text document.

There are two ways to identify the keywords from the Document Text:

  1. Use all the words in the document text and depending upon their frequency promote them as keywords or drop them as noise ( words with higher frequency are generally noise words )
  2. In general, scientists maintain a keyword collection with which they do the lookup to identify the set of keywords that generated the document.

Both the methods have upsides and downsides. The trick here is to have a method by which we select only the contextually meaningful keywords from the document text.

Here is one of the method to enrich the document vector, assuming that the document content is homogenous ( few
similar semantic contexts )

  1. Generate the summation vector ( resultant vector ) using all the chosen keywords
  2. Correlate all the chosen keywords individually against the resultant vector (look out for keywords that show negative correlation or very low correlation)
  3. Place a cutoff of correlation score to be 0.2 (when cosine similarity is 0.2, the angle between the word and
    resultant vector is around 75 degrees! )
  4. Remove the words that do not fit the cutoff (threshold) from our selection set of keywords
  5. Generate the Resultant vector again based on the chosen keywords ( after the above filtering )
  6. Iterate steps 2,3,4,5 to get the rejected words ( iteration rejections are to be appended to the master rejection set ) and accepted keywords.
  7. Stop iteration when there are no more keywords to be rejected.
  8. The final summation vector is the enriched resultant vector, which would model the document much closely than the first one we started with.
  9. We may correlate again the accepted and rejected keywords against the enriched resultant vector to witness the boost in maxima of correlation score for the accepted items and minima of correlation score for rejected items. ( the positive correlations become more positive and negative correlations become more negative in the due course of iterations ).
  10. The final set of the accepted items could be assumed as the actual set of keywords that generate the document.

Happy Vectorization…

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Greeter Application appears to be crashing. Attempting to use a different one.

July 17th, 2008 No comments

Before the login screen appears in Fedora, you may get a popup saying
“Greeter Application appears to be crashing. Attempting to use a
different one”. You may think, this could be due to video driver fault.
In most of the cases, it is because your root directory “/” is 100%
full. When you free you space in the “/” drive, the problem goes away.

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Backdoor Entry in IT companies

July 17th, 2008 3 comments

Lately, I was browsing through Orkut
and was surprise to see a guy repeatedly boasting in various C++ forums
that he can buy a position in big IT companies via backdoor entry. He
was even quoting the price for getting recruited in different IT
giants. I thought it’s a hoax message and left it there.

Recently
I had visited a self-financing engineering college for an Invited Talk.
I had an opportunity to talk to the placement officer of that college.
He said, there has been a radical change in the process of inviting
recruiters to the colleges. All bigger IT companies have a much a
bigger HR department with a lot of HR executives. Amongst HR heads,
there are people who can do “special service” for a premium price. The
“backdoor entry” in the former paragraph is a manifestation of this
kind of “special service”.

The “modified” invitation process is;
the placement officer/management strike a deal with possible HR heads
on a per-head basis. The placement office pays the HR head lump sum of
money (black, ofcourse!). In return the HR head ensures the agreed
number of recruitment from the college to their company. There are no
stakes for the HR head, because most big IT companies have 100-200%
human-resource buffer for their projects. Most likely, the backdoor
recruits are for the reserves only. Moreover, the volume of employees
in a big IT company is so much that people don’t really know the team
members by name. An interesting example is; one cannot find the exact
number of employees in TCS at any minute (people come in and leave out
so much in TCS).

All these should come to an end soon. Recession
in IT industry is coming back. Only professionals with quality are
going to survive. Let’s see what happens…

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Weathering course

July 17th, 2008 No comments

There can be several problems with the weathering course laid on top in the terrace. I am facing a very peculiar problem with it. In my apartment, we are seeing water dripping out the roof via the parapet-roof joints several days after rain. Water oozes out via a crack that has formed at the joint of the parapet wall and the roof RCC. Also, the dripping is happening near the roof drain vents, which happens to the lowest area of the roof-top.

Generally while constructing roof and weathering course, masons leave an inclination of level towards a corner of the roof for the rain water to drain comfortably. In our case, we are seeing water draining through a crack between the parapet wall and the roof in the vicinity of the drain vent. Since it is near the drain vent, we were suspecting the thickness of the weathering course. As there is a forced inclination in the weathering course layer, the thickness of the course near the vent should be lesser than the other areas of the roof.

When we consulted with a civil engineer, he was giving a completely different explanation for the problem. He was suspecting the iron-oxide coated shells layered on top the weathering course. He was saying rain water might have gotten into the core of the weathering course through the gaps between the iron-oxide shells. The water thus gotten inside keeps the weathering course in soaked condition for a long time. Here the core of the weathering course behaves like a sponge to absorb all the water that seeps inside. Later, the water thus absorbed percolate to the lowest side of the roof slowly, which may take weeks time (like our case). Once the amount of water reach a significant quantity at the lowest side, it tries to escape somehow. In our case, the escape vent is a crack that had formed between the roof RCC and parapet wall construction.

So what is the solution to this problem? Should we take out the weathering course completely and redo from scratch? Should we be finding the source of the problem, the places were rain water seeps inside the core of the weathering course? Should we increase the thickness of the lowest side of the roof ? All these cannot be permanent solutions or they may not be easily doable. The
solution that I have is the following. Since the water collected is trying to escape, let’s give it an easy way to escape. Finally, we don’t want the core to be soaked. So we should be placing vent pipes just above the RCC roof level and be placed amidst the core of the weathering course at the lowest side of the roof. We know that water from all the areas are reaching here percolating for weeks. If there is an easy vent out like the vent pipe, the accumulated water can escape easily instead of dripping out of a crack. If we can find potential spots in the roof for more vent holes, we may very well preserve the consistency of the core of the weathering course for a long time. But that’s going to be pretty tricky!!

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Mr Jayachandran, JE/Avadi BSNL Exchange

July 17th, 2008 No comments

I solemnly agree that there are few passionate people in public service departments. I reside at Thirumullaivoyil which comes under the control of Avadi Township. I had recently applied for BSNL broadband connection, which took little more than a month to really materialize. The broadband department of Avadi Exchange was quick, but the Linemen and the Broadband servicemen were poor. The guy who had come for installation knew nothing about broadband connection. But he was boasting that he is the incharge of all broadband activities. Poor we!

Though, it had taken little extra time, it was really worth waiting for. The speed of BSNL broadband is awesome. While checking the download speed, the ticker showed more than 1.6Mbps. Hmm, all these excitements shattered on day 3. The telephone line went dead. I had made complaints through all possible channels viz. BSNL portal, via 198 AVR, and also
through the customer care centre of Avadi Exchange. It is more than a week now, and there is no improvement to this.

But like a ray of hope, I got hold of the BSNL JE’s office number. The JE is Mr. Jayachandran. This man is very different from another government employees. I was told that the JE would respond to customer problems ASAP. I had to try several times to get the number connected. At around 11 AM, I got lucky to get the JE on phone. To my surprise, this man is really different. He heard my problem patiently and instantly gave orders to the field people (I was able to hear him calling the Linemen by name to fix the problem immediately). It was like breeze to see a public service person in action. I thanked him several times to have responded very fast.

But, when I came back home, to my surprise the phone line is still dead. Most likely it should be the mistake of the Lineman again. Even though the service call is not completed, I am not getting frustrated. It is just because the way Mr. Jayachandran acted so responsibly.

Mr. Jayachandran, JE BSNL Avadi Exchange, may be contacted at 044-20029423. He comes to office only at 10.00AM Monday-Saturday.

Update 27.01.2009
1. JE’s number has changed to 044-26383456
2. Thirumullaivoyil::CholambeduMainRoad Line man’s number is 044-20006064

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DG834G and BSNL Broadband

July 17th, 2008 1 comment

I have a super-fast (by today’s standards) broadband connection provided by BSNL. But BSNL had provided me a wired ADSL router, which has only one RJ45 Ethernet port. I have two desktops and one laptop with me which needs to be connected to the Internet through the broadband connection. BSNL also provides a wireless type 2 ADSL modem, but the general review about that is not so appreciable. Lately, I was told about Netgear DG834G which could be used for my rescue.

I bought Netgear DG834G from Ritchie street, Chennai for Rs 2900. This is a type 2 modem that comes with IEEE 802.11b/g hardware that can support upto 54Mbps data transfer speed and four 10/100Mbps Ethernet ports. The configuration of the modem is pretty straight forward. I had chosen the manual ADSL configuration method in setting up. I had all the details borrowed from the UTStarCom modem given by BSNL. A quick summary of the modem setting is as follows:

ADSL Setting

VPI: 0

VCI: 35

Multiplexing Mode: LLC BASED

DSL Mode: ADSL 2+

Basic Settings

Does your Internet connection require a login? YES

Encapsulation: PPPoE

Login:

Password:

Service Name: dataone

Idle timeout: 5

Internet IP Address: Get Dynamically from ISP

Domain Name Server: Get Automatically from ISP

Network Address Translation: Enable

There was a catch here. I did not know the BSNL password. From the ADSL modem, I could get only the username. So I tried using “password revealer” to get the password configured in the BSNL modem (I got the modem pre-configured while BSNL installed it in my home). None of the
password revealers work on XP and Vista.

Linux Fedora came for the rescue. Fedora comes with Ethernet promiscuous mode intercepting
tools like “tcpdump”, “iptraf” etc. I decided to intercept the ADSL modem configuration page for capturing the password which “could” be sent as plain text in the URL. TCPDUMP becomes an ideal tool for this requirement. I summoned “tcpdump” to capture all the packets destined to 192.168.0.1 (ADSL router IP). The command is the following:

tcpdump -A dst host 192.168.0.1 -s 5000 > dump.file

I had asked the command to redirect the outputs to “dump.file”, so that I can check the content offline. Once the command started, I opened the ADSL page in my browser (on a machine connected to ADSL via ethernet; also to remind, “tcpdump” runs on this machine!). While browsing
through the authentication page and the following pages, “tcpdump” started capturing all the html text transferred between my machine and the ADSL router.

Bingo, the URLs are dumped in the file. To my surprise, the password assigned for my BSNL account was “password”. Later, I figured out that “password” is the default password assigned
to all pre-configured ADSNL modems. Anyways, even if the password is different, my technique would have fetched the password for me.

This technique will not work for sites like yahoo, etc. Because they don’t send the password as plain text, rather they send the MD5 hash equivalent of the password. This technique will not work for any site that is running on HTTPS, as everything sent across or received is encrypted using 128bit SSL encryption.

Netgear DG834G promises reasonable signal strength for 35M (~100feet). It works even if I keep
the router is one corner of the house and try to access it from any other place out of which some areas are reachable only after multiple left and right turns.

DG834G is awesome. I recommend this router for domestic BSNL broadband use.

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Configuring Wireless LAN of Dell XPS 1530 in Fedora 8

July 17th, 2008 No comments

Dell XPS 1530 comes with an Intel Pro Wireless 3945ABG Hardware.

In fedora 8, by default the device is detected and an appropriate driver (iwl3945) is loaded as well. If the wireless network is not secured, the interface works without any modification.

I had configured by ADSL router to have WPA-PSK encryption based security. To make my laptop work with this secured network, the default network configuration dialog does not suffice. But still, we need to setup something in that dialog as well.

  1. Open system-config-network dialog, choose to edit the wlan0 interface.
  2. Select the “Wireless Settings” tab.
  3. Set Mode as “Managed”
  4. Set Network name (SSID) as “XYZ”, where “XYZ” is the SSID you had
    configured in the router. You may also leave it in “Auto” as well.
  5. Leave the other inputs as it is.

From the command line, run “iwconfig” to see the status of your interface. You may see something like the following:

wlan0 IEEE 802.11g ESSID:”NETGEAR”
Mode:Managed Frequency:2.462 GHz Access Point: Not-Associated
Tx-Power=27 dBm
Retry min limit:7 RTS thr:off Fragment thr=2352 B
Encryption key:off
Link Quality=0 Signal level=0 Noise level=0
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

Note, I have configured my SSID to be “NETGEAR”.

Since we have not enabled the security “thing”, we are not able to reach the Wireless Access Point. To enable that we need to have the “wpa_supplicant” tool. Using wpa_supplicant, we can bridge the connectivity and security.

First create the wpa configuration file using “wpa_passphrase” command.

wpa_passphrase
Ex: wpa_passphrase NETGEAR alphabeta

This command would generate a file like the following:

network={
ssid=”NETGEAR”
#psk=”alphabeta”
psk=d0392dff9de884a7163058cebb41592bf7872decda1c8b79b072359bc5e93cac
}  

Dump this output to /etc/wpa.conf

Now, you have to run wpa_supplicant as:

bash# /usr/sbin/wpa_supplicant -Dwext -iwlan0 -c/etc/wpa.conf &  

Note,
I have used the “wireless generic extension (wext)” for the driver configuration. You may get some log message like the following:

Trying to associate with 00:1b:2f:a3:54:f8 (SSID=’NETGEAR’ freq=2462 MHz)
Associated with 00:1b:2f:a3:54:f8
WPA: Key negotiation completed with 00:1b:2f:a3:54:f8 [PTK=TKIP GTK=TKIP]
CTRL-EVENT-CONNECTED – Connection to 00:1b:2f:a3:54:f8 completed (auth) [id=0 id_str=]

At this point you are probably connected to the Wireless Access Point. Try running “iwconfig” command. The correct output should be like:

wlan0 IEEE 802.11g ESSID:”NETGEAR”
Mode:Managed Frequency:2.462 GHz Access Point: 00:1B:2F:A3:54:F8
Bit Rate=54 Mb/s Tx-Power=27 dBm
Retry min limit:7 RTS thr:off Fragment thr=2352 B
Encryption key:5A83-9BBE-BA9F-5C2B-46D1-0FEC-CE66-475F-A44A-DD05-4B16-63F3-3474-0C46-464A-6CF0 [3]
Link Quality=97/100 Signal level=-29 dBm Noise level=-64 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0  

try running “/sbin/ifconfig” to see whether you have the device up with an IP address. If IP address is not assigned, run

/sbin/service network restart
or
/sbin/dhclient wlan0
or
/sbin/ifup wlan0

You may probably see a “wmaster0″ interface as well, which may be ignored.

Most likely you are done by now.
Happy wireless networking.

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ஓடாத மின் விசிறி

July 15th, 2008 No comments

மின் விசிறி ஓடாததற்கு பல காரணங்கள் இருக்கக்கூடும். சிலவற்றை இங்கே காண்போம்.

  1. துண்டிக்கப்பட்ட மின் இணைப்புகள்
    1. ஒரு அசைவும் இருக்காது
    2. டெஸ்ட்டர் கொண்டு சோதனை செய்ய வேண்டும்
    3. மின்சாரம் இல்லையெனில் மெயின் போர்டை சோதிக்க வேண்டும்
  2. செப்பு கம்பி சுருள் துண்டிப்பு (காயில்)
    1. தீயும் நாற்றம் அடிக்கலாம்
    2. கம்பி சுருளை மாற்ற வேண்டும் (செலவாகும்)
  3. தொடக்க கபாசிட்டர் வேலை செய்யாதிருத்தல்
    1. சிறிதாக ஒரு அதிர்வு இருக்கும்
    2. முன்னும் பின்னுமாக விசிறி சுழல முயற்சிக்கும்
    3. கபாசிட்டரை மாற்ற வேண்டும்; 2.5 MFD/400V; சுமாராக 50ரூ இருக்கும்
  4. பால் பியரிங் தடங்கல்
    1. சிறிதாக அல்லது பெரிதாக அதிர்வுகள் இருக்கும்
    2. தீயும் நாற்றம் அடிக்கலாம்
    3. மிக சூடேரும்
    4. பியரிங்கை மாற்ற வேண்டும் (சோடியாக மாற்றுவது சிறந்தது)
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