Life and Living

A line follower robot

admin — Sat, 06 Mar 2010 17:05:23 +0000

It was a assignment to program a line follower robot. We have five sensors to detect a black line on a white surface. In my group we were two members:- me and Sufi. What we do is that we wrote a program in BASIC that will tell the user to put the robot sensor on white surface to take input data of the sensor readings for white. When reading is complete it will say to put the senosrs on the black to take the sensor readings for black. When the reading is complete it will seek black line. If the middle sensor is in black line the robot will go straight. If all the left sensors are in black, it will turn 90 degree to left. Same action for right 90 degree turn. If the black line is detected on any side of the middle sensor, the robot will turn lightly to make the black line appear on the middle sensor. If all the sensors are in white the line follower will stop moving.

Our report is here.

Curve

admin — Wed, 03 Mar 2010 17:57:44 +0000

Curve is a combination of a lot of small segmented straight line. So small segment of straight line is the source of all kind of curves not in the drawing board but also in our nature and life. Curve has some strange things over straight line. You can create a curve with some small segmented straight line but the reverse is not possible. If you join few curves it will create a complex curve but not a cruve. But putting curves of same shape and curvature may create a straight line like thing (not really a straight line).

A beautiful World

admin — Sun, 28 Feb 2010 18:16:41 +0000

A beautiful world does not mean that the world is full of precious and eye catching things. When we can say that our world has become beautiful? It is true that the world has a lot of beautiful things to notice. Are this enough to declare our world beautiful? I say no, because a beautiful world is another definition. Balance always plays a major role in beautification. A beautiful world is meant to be a balanced world in ecological, economic and cultural sense.

Every person has his or her own world, when will we say his or her world is beautiful? It is not easy, because a person may not express his or her world to other. Hiding personal world does not mean that that his or her world is nasty. When a person has a nice environment, cool friends and relatives in contact, just, love, devotion in mind we can say he or she has a beautiful world.

Beauty by definition

admin — Sat, 27 Feb 2010 17:24:07 +0000

What is beauty? Something pleasant, smooth, easing or something else that makes a sense of feeling good. How can we define beauty? How can we measure it? Well it is relative to the tastes of the human being. We say a thing is beautified when external ornament is applied. We say a thing natural beauty when the thing is genuine and nothing is applied on it. The adjective beauty creates a lot of sense in our mind, depending on situation.

I smell a rat

admin — Fri, 26 Feb 2010 20:52:09 +0000

I have just created a thread in webhostingtalk.com about a review of my host. The thing is that my site is moved from the initial server. One of the guy from that forum traced it and replied it. They smell a rat about my correctness of information. It is true that I bought my hosting from mellowhost.com. Mellowhost has many servers. The admin moved my site from one server to another server due to package management. He notified me about it. What ever I told the man who made a doubt to trace ip history of the site to see if I am telling right or wrong.

A river cruise

Sondha — Fri, 26 Feb 2010 18:21:27 +0000

Recently my batch arranged a river cruise from Buriganga river to Meghna river. I had never attended a river cruise before. As we were the organizing batch, we had a lot of duties. I was assigned the duty of transportation from Department to Ship and ship to department (return). My friends were assigned other tasks. I told the bus management authority to take us to Sadar Ghat Docking Station at 7:30 AM, they came in right time, but it took more than one hour to start for the docking station. We were to take the necesary chairs, drinks, waters to the bus, make sure that the teachers and other batches are got in the bus. I myself, Zia, Nayan, Tazim, Jewel, Maska and some junior student carried these stuff to bus. I myself, Tulu, Nazmus Sakib, Shamiul Tied banners in front of the buses. We had two double decker buses for transportation to docking station. At about 9:00 AM we started for Sadar Ghat Docking Station. The Juniors were singing, so far I have heard the song is like “oo tunir ma, … tuni kotha sune na…”. We reached Sadar Ghat within half hour. Sadar Ghat is a nasty place. The water of Buriganga river stinks. We got on our ship. It was M.V. King Shomrat. We provided breakfast after the ship launched. Our female classmates arranged cultural program involving teachers and students. At noon we provided lunch and we returned at evening.

Buggy header in php

admin — Sat, 13 Feb 2010 16:28:11 +0000

Today, I got a problem in a php script. I was using header() function in the if-else branching. The code is something like

if(condition1)

{

header(”Location:dummy.php?err=1″);

}

else

{

header(”Location:dummy.php?err=2″);

}

if(condition2)

{

header(”Location:dummy.php?err=3″);

}

else

{

header(”Location:dummy.php?err=4″);

}

a contition may fullfill both condition 1 and 2. But in this case I want to go through the first if clause. I run the script and saw that the final page is dummy.php?err=3. But I supposed to get err=1. The question is why this happened? I found its answer. The first condition is fullfilled and the page is directed to dummy.php?err=1, the script does not exit, rather it run from where it was redirected. Then the second condtion is fullfilled. So the page is redirected again to dummy.php?err=3.

The solution is to use exit() function after each header() function so that the script cannot run further after redirection.

The correct code will be,

if(condition1)

{

header(”Location:dummy.php?err=1″);

exit();

}

else

{

header(”Location:dummy.php?err=2″);

exit();

}

if(condition2)

{

header(”Location:dummy.php?err=3″);

exit();

}

else

{

header(”Location:dummy.php?err=4″);

exit();

}

File permission in Ubuntu

admin — Fri, 12 Feb 2010 17:21:55 +0000

I use ubuntu. I found a problem in ubuntu file permission. I have made a php script to delete a file. The file run on CentOs server correctly, but if I run that script on my ubuntu localhost, it shows me a warning saying “Warning: unlink(toberemoved.php) [function.unlink]: Permission denied in /var/www/remover.php on line 5“.

The problem is that in ubuntu root access is not available directly. To create delete file we need to issue an sudo command, that asks for the root password. But who run the php script is a client, who have no root access, that is why it shows an warning. If you are in such situation issue a command “sudo chmod +w foldername”, so that the client can wirte and delete file to that folder.

Color Your Life###2

admin — Fri, 12 Feb 2010 11:45:28 +0000

Sometimes I take photos. I found a virtual pond type thing in front of your department. I saw some shrubs udner the water. I took a photo of it.

Shrub under Water

Export mysql database

admin — Thu, 11 Feb 2010 13:29:32 +0000

Yesterday My classmate Rinku asked me how to export mysql database. He said that using PhpMyAdmin is pain to download the database everyday. So he needs a button which will do the job of PhpMyAdmin in a single step. That is why he needs the system of exporting a database. I knew how to import database, it is a simple command line script. %mysqlimport -p -u root < file_name.sql. But I dont know about exporting a database. Because I need to export database rarely. I told him to try with mysqlexport command. But this is not an sql comman. This does not work. I came home and googled about it.

I found that exporting a database is also known as dumping. The command is %mysqldump -p -u user_name database_name > file_name.sql.

Simple! Isn’t it?