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Archive for February, 2009

A beautiful poem

February 15, 2009 Leave a comment

I read this yesterday and i find it really expressive

A Valentine is nothing like
A chocolate or a rose.
For in a week these shall be gone,
But Valentines remain.

If love were always sweet to tongue
Or fragrant to the nose,
Each day would be like Valentine’s,
And we would go insane.

A Valentine just hangs around
Waiting to be kissed
Long after special days have passed
And every days are here.

So one is wise to choose one well
And chocolates to resist.
For in the midst of mania
It’s nice to have one near.

courtesy:www.poemsforfree.com

Categories: All Misc

Memristor:The missing circuit element

February 9, 2009 3 comments

We are very much aware of the three basic elements of electric circuits i.e. the resistors,the inductors and the capacitors.In september 1971, Leon Chua published a paper named as “Memristor:The missing circuit element”.In his argument he first considered the general equation of the capacitor
i = C(dV/dt)………………..(1)
but according to him when the capacitance varies with time eg. C = (5+3sint) then it is found that eqn (1) doesn’t give the correct value of current for a given applied voltage. If we integrate eqn (1) we’ll get
q(t)= C(t)V(t) …………………(2)
and we would say its just the same as eqn(1) but its not when its not linear or in other words when the capacitor is time varying. So when we put C= 5+3sint in eqn(2), we get
q(t)=(5+3sint)V(t) if we differentiate this we’ll get

i = (5+3sint)dV(t)/dt + (3cost)V(t) so this is the missing term if we solve it by eqn(1). Now we can write for inductor as well.

V = L(di/dt)
if we integrate we’ll get Φ =Li or rather Φ(t)=L(t)i(t)
Now, we have four items

* Current(i)
* Voltage(V)
* Charge(q) i.e integral of i
* Flux(Φ) i.e integral of V

So there are relations between each two relevant terms but what was missing was a relation between flux(Φ) and charge(q).So Leon in his paper formulated

Φ(t) = M(t)q(t)

if we differentiate we can conclude that M(t) has the unit of Ohms so he named it as ‘memristor’. As it can store memory in them unlike usual resisters.So this is the history of memristors.memristor02

In May 2008, Hewlett Packard made it possible and made memristor a reality.
So can you imagine lighting a bulb and then pulling out its plug from the source and the bulb still glowing.Think about memristors!!!

memristor

The defect with memristor is that it is not lossless hence it will dissipate energy and so the above scenario cannot be reached but there are concepts of “Memory capacitors” and “Memory Inductors” which are proven to be lossless devices which i’ll talk in the next post.With them coming the above scenario would be nothing less than a reality!

Categories: Electronics Tags: ,

Hidden movie

February 2, 2009 2 comments

For those who don’t know about the hidden movie …”star wars”
Follow these steps to watch it…


Step1. Connect to the Internet.
Step2. Go to Start>Run>cmd and type 'telnet' (without quotes) in command prompt
Step3. Type 'o'.This will take you to a new line.
Step4. Type 'towel.blinkenlights.nl' .A screen will appear with some words in the middle if you wait for
sometime it will show you another screen with some words in the middle.Wait for a bit
and the next screen takes you to the Star Wars movie.

Enjoy Watching!!

Categories: Codes
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