Notes for the COAM External

Hi,
I doubt you'll read this, but it must be written. Here are some notes that should help the next time you take a viva:

1. Why don't people use Pentium 5, Pentium 6 etc?
Probably because they don't exist. That must be most of the reason.

2. Today's processors don't follow Moore's law.
Yes, they do. Your insistence that they don't does not change reality.

3. Dual core processors are the latest innovation - released 1-2 years ago.
No. There have been dual core processors at least since 2001.

4. Shrinking the manufacturing process increases total power consumption.
This is just stupid. It increases idle power consumption, not total.

5. Process shrinks are the only way to increase performance.
It's one way. There are many others.

6. Dual core processors exist because it's impossible to increase the clocks on a single core beyond a limit.
It can be done, refer Pentium 4. Dual cores exist because they're better at handling multitasking.

7. Pentium 4 dual core is the latest processor from Intel.
The only thing good about this is that you haven't seen Intel's garbage advertisements for the '2010 Core Processor Family'. You know what's bad? You don't read newspapers, or watch TV.

If you do read this, at least you will know that the world's changed since Ray-Bhurchandi was published. Just sayin'

Reassuring - I

I'm heading home from Manmad. It's 1 AM, the train is almost two hours late. After waiting for a bit at the station, the train finally arrives. I pick up the bags and board the train. S-6 looks more like a 'General' coach, with people sleeping in the aisles. I finally get to my berth - it's a middle berth. The berth is set into place, and I'm about to lie down. I suddenly notice that one of the chains holding up the berth is not taut. The entire berth is being supported by only one chain.

It makes me a little uneasy, but since there's nothing I can do, I try to sleep. The uneasiness just won't go. I keep wondering, will a single chain safely hold up my weight? The uneasiness gives way to calculation...

Approximate oval chain links as rectangular chain links (Since I've never been able to calculate stresses in curved members with a calculator, and certainly wasn't going to succeed with mental math)
Therefore, the links can fail in shear.
Yeild Strength of Mild Steel - Approximately 200 MPa (Close enough)

Shear strength is taken to be half of the Tensile Strength - 100 MPa

Diameter of chain links - 5 mm (Measured by 'looking')

Cross sectional area - (Pi/4)*5*5 = approx 20 sq. mm (actually 19.63)

Load on chain links - 90Kg x 9.8 = approx 900N(My weight + weight of berth)

Shear stress on any chain link - 900/20 = 45MPa

Permissible Shear Stress - 100 MPa

Conclusion : The berth will not fall, even though only one chain is holding it up.

Reassured, I sleep.

Criminal Intent (or the lack of it)

I'm only in college. I still find the lack of criminal intent in the people around me appalling. Really. Just the other day, I was on a public computer in college, when enthu pointed out one entire folder lying on the desktop. A particular set of students had downloaded a set of documents that they would copy entirely for a project. I don't really have a problem with people copying projects off the internet. There are times when the spark of inspiration simply does not come. However, when you're doing something wrong, at least DO IT PROPERLY. How can you leave traces on a computer that is accessed by a large number of people? And on the desktop?

I'd almost forgotten about writing this post, until (new character, YAY!) Gen. L. Oblivious reminded me with a 'lack of criminal intent' incident of her own. Gen. L. Oblivious is properly known as General Lee Oblivious. Now that the introductions are out of the way, the incident:

Gen. Oblivious : I'm spooked even when I walk around college!!
greySith : lol wtf... What's to be afraid of in college?
Gen. Oblivious : oh theres plenty...
greySith : Name one realistic reason
Gen. Oblivious : The other day... I was going through a RANDOM guy's phone to choose a pattern for the department sweatshirt and the next picture was... no prizes for guessing... mine...
1) staring at the ceiling in the boring math lecture
2) at the cafe house with a disfigured mouth chewing on something
and three more like that
greySith :@
Gen. Oblivious : Felt like I was being watched by Big Brother...

Now, I'm not the sort who would take pics of women without them noticing just for the heck of it. But, if I had to do it (for a bet etc.) I really wouldn't have taken pics of the girl and then handed her my phone to look through some pics. How daft is that!?

Some of you might say that criminal intent is only needed by people who do things that are wrong. I tend to disagree. You're online now, reading my blog. The internet is an unsafe place. Very unsafe. It is ideal to leave as little trace of what you do online as possible. Whether or not it is happy information or incriminating information, information on the interwebs can be used against you. Criminal intent does not only mean covering up wrongdoing. I consider it to mean protecting any information from people who shouldn't have it. On the internet, as a certain cartoon character would say, 'be wawy wawy caweful'.

Note: Gen. Oblivious is not to be mistaken for Captain Oblivious. She far outranks him!

Conscience

The scene: fag end of a horribly annoying robotics paper. Have just reached a problem that is in two parts. Part 1, I knew exactly how to do. Part 2, I assumed would never come in a paper, and if it did, 'I'd figure it out.'

So now I'm there, 'figuring it out'. Three possible answers come from the three possible ways of doing the problem - 2.5 years, 3 years and 3.33 years. The numbers are running through my head. After a brief battle in my head, I finally decide on 2.5 years.

About three minutes later, the paper ends. The usual post-paper rapid copying session begins. I wearily close the answer booklet and keep the pen down in disgust.

The guy in front of me looks at another guy,

Guy 1: What's the answer to the payback period problem?
Guy 2: Three years
Guy 1: Great, I got the same answer!

Almost instantaneously, a demon and an angel appear on my shoulders. (Okay, so they don't, but we'll pretend that they did).

Demon: Go on! Change it!
Hands eagerly start looking for the last pages of the answer booklet
Angel: NO WAY!
Sheepish hands keep looking for that page, albeit more slowly
Demon: Come on! You haven't done this for three-and-a-half years. No one will grudge you this once!
Happy hands find the problem
Angel: Now is no time to begin.
Brain starts to think of the method that gives 3 years as the answer
Demon: Al..mo..st.. there!
Brain has decided the changes to be made. Hand slowly moves towards pen
Angel: You decided that 2.5 years made the most sense. YOU made that choice, now see it through, no matter what.

The whole 'back your decisions' thing suddenly snaps the brain out of the angel-demon reverie.

I'm glad I didn't change it. Turned out later that I had 'figured it out' the correct answer. And I'm proud I didn't give in. My sinless record in college survives!

Gear Happy

The other day, I was in Camp, and noticed this guy who rode past at high revs in the first gear. My thoughts, in order, were:
'Poor sod. No one told him his bike has five gears'
'Or maybe no one told him where the shifter was'
'He might also have thought his pulsar was an automatic transmission bike'

I love the gearbox. A well designed gearbox ranks in the same category as digital watches and soap bubbles, when it comes to making people happy. People accuse me of using the gears too much, but god gave us the gearbox to use it! Over the past few months, I've practised a ton of gearbox skills, such as engine braking, cutting down brake use by 90%, seamless shifting etc. It's a lot of fun.

People who ride (or drive) ATs have no idea what they're missing out in a Manual. This post is probably a little random, but is serves a purpose. I want to pay homage to the guy who invented the gearbox (and God) for this priceless gift to mankind. Thank you.

Don't Panic!

With that reference to the lord of humour, I'm going to talk today, about braking on wet roads. A lot of people tend to fall while riding on wet roads. This has a lot to do with the manner in which the brakes are applied on a two wheeler. Most people believe that on wet roads you must forgo the use of the front brake and use only the rear brake. This, is a very risky thing to do. I'm going to explain, with the help of a little bit of mechanics, how brakes should be used in the wet (or even dry).

Before we get to the braking though, a few general tips. The water on the road reduces the friction between the road surface and your tyres. While riding on a road with a little bit of water (i.e. not standing water), the water will tend to reduce the friction (or grip) available to you by about 15%. So, for starters, ride about 20% slower than you would on dry roads. Secondly, maintain distance between the vehicle in front of you. On a dry road, I remember rearset saying somewhere that you should maintain a distance to the vehicle in front of you such that you can see the tyres of that vehicle. On a wet road, extending this distance further, as much as a car length is a good idea. Additionally, avoid riding on anything that is not tar/concrete, i.e. painted signs, tiles, metal manhole covers, etc. That 5% difference in grip may be the difference between you being on the bike and on the ground.

Now, on to the braking part. Consider a two wheeler travelling on a stretch of road,


In the picture above, imagine the long straight line to be the body of your two wheeler. Consider four frictional forces in that figure. Fft and Ffb are the frictional forces at the tyre-road interface and brake respectively for the front wheel. Similarly, Frt and and Frb are the frictional forces at the tyre-road interface and brake respectively for the rear wheel.

In order to slow down the bike, without causing a wheel to lock up, the frictional force at the tyre-road interface must exceed the force applied by the brake at all times. As long as Fft exceeds Ffb, the frictional force at the tyre-road interface will force the tyre to keep rotating. If Ffb becomes higher that Fft, the tyre will simply stop rotating and lock up. This would imply that you should apply equal, but limited pressure on both brakes to brake safely. There is another factor though. The moment you start braking, the body of the bike tends to lurch forward due to inertia. This motion compresses the front shock absorbers and allows the rear shocks to expand. So, once you start braking, the picture changes to this,

Shocks are not perfect, and therefore will transmit force (even though they're supposed to absorb it). Therefore, you now have a state where there is a greater load on the front wheel than there is on the rear wheel. This means that Fft now greatly exceeds Frt. It is easy now to lock up the rear wheel, and correspondingly hard to lock up the front wheel, because the limiting values of Ffb and Frb have also changed.

This is the reason why bikes always have a stronger brake on the front wheel. The explanation above holds for dry and wet weather. The correct method for braking therefore, is to start braking with only the rear brake. Once weight transfer to the front begins, slowly start using the front brake, and reduce the pressure on the rear brake. This ensures that you're less likely to lock up either wheel.

Don't Panic
If you understood what I just said, you should be less likely to lock up the front wheel. Rear wheel lock ups are still possible. If you do lock up the rear, whatever you do, don't panic. Because the front wheel still isn't locked, chances are that you'll still be going in a straight line. Gently release the rear brake, more often than not, it'll start rotating again.
Always be prepared to fall. There's no technique in the world that can ensure that you'll never fall. You WILL fall, all you can do is to reduce the frequency. When you are open to the possibility of falling, if you do fall, you'll probably get up, pick up the bike and start riding again. If you believe that you can never fall, when you do, you'll be too stunned to do anything about it.

That does it for my first biking techniques post. Feedback on whether or not that was coherent and understandable is welcome.

When Curses are Blessings

Some of you may know, that we have a new Baba. Abba is passe. Make way for,
*drumroll*
The lord of the universe,
The protector of the innocent,
The decimator of the pseudo-scientists,
The instigator of scientific thought,
The sampler of the delicate rose,
The photographer of the beetle,
The Rose-Beetle Baba, VRD!

So you should guess why he cursed me. We were out on a little trip out of the city. Staying overnight at a village after climbing (and unclimbing) Torna. And we went on and on and on making terrible jokes about the new Baba. He took it quite well for most part, but as the jokes got worse, you could see his expression changing. From the calm and collected look he always has, you could see a pained look entering his face. Finally, he snapped.

[Useful background information]
VRD rejected an IIT to grace our college with his holy presence. Some say that if you know VRD's actual grades, you would have an accurate value of infinity. We usually get grades on a scale of ten. He on the other hand, would be scandalised if he got anything less than ten.
[End of useful background information]

Gathering his reserve, VRD put in as much sneer as a nice chap like him can put into his voice, and cursed me. He thought it was the most terrible curse one could give. He whispered, with a manic grin,
"You, GreySith, You who have insulted me, the holy baba, I curse you! You, will get the paltry result of NINE POINTS for this semester!" A frightening evil laugh followed.

I didn't know what to do. Here I was, struggling to make eight, and he curses that I shall have nine! I found it hard to supress my joy, but I heroically did. I looked at him, glum and sullen, as if it truly was the most terrible thing in the world. He was duly satisfied with my reaction.

The results have come around, and the guy who was struggling to get past eight, has ended up with 8.6! Truly, Jai ho baba!

I'm a mid 60s guy

These are words of Enthu. Uttered on the way back from Nasrapur. For a little background, Nasrapur is a village on NH4. We have an active Astronomy club, and we had decided to go to Nasrapur for a star party. Enthu and I went to the site a couple of days earlier to perform a recce of the site, to ensure it's good for our purposes.

We left Pune at 6:40 PM, and got there at around 8:30 PM. Most of that time was wasted in the city. Once we got out on to the highway, we were doing a comfortable average of over 60kmph, touching 85 odd occasionally.

On the way back, I offered to let Enthu ride. He tells me, "I'm not a big fan of speed... I'm a mid 60s guy. You're pretty confident on the bike- when you took that banked turn at 78, 'gote kapaalat geli hoti' for lack of a better phrase." I told him that the bike inspires such confidence.

A push of the starter and a minute later, the mid 60s guy is cruising along at 75kmph and taking banked turns at 80. And touching speeds around 90kmph.

We did in excess of 70kmph on the highway that night. That's a pretty impressive figure on Indian roads. And the rider was riding this particular bike for the first time.

Once we've stopped he tells me, "This bike is fantastic! It just feels so assured and planted to the road! I've ridden many bikes, and never felt confident enough to cross 60kmph for too long a time."

I agree. The Apache RTR is one of the finest pieces of engineering to come out of an Indian company. Too bad the seat is bad, and too bad the engine vibes a bit. But you can't have it all. I'd say the brilliant engineers at Hosur can take a bow.

Dhak Dhak NO!

Dear Hero Honda,
I'm writing this letter because as a part of the market section that you're trying to target, I'd like to make a suggestion.
FIRE EVERY SINGLE PERSON IN YOUR MARKETING TEAM.
No? Again? Okay.
FIRE EVERY SINGLE PERSON IN YOUR MARKETING TEAM.

What was your HR team thinking when they employed the marketing team?

Please answer a few questions for my satisfaction:
1. Why did you name an otherwise okay bike 'HUNK'
2. What makes you think men want to ride a hunk?
3. Does a rider on a hunk really turn into a bison at will?
4. Does Hrithik Roshan's Karizma really have a nitrous oxide system?
5. What made you think a red bike with checks on it looks cool?
6. Did you actually think before you agreed to make a PINK Passion?
7. Did you actually even think before naming a bike Passion? Or pleasure?
8. Does anyone of the Next Generation really ride a Splendor NXG?
9. Does anyone ride a Splendor NXG?
10. Does the 'new' CBZ extreme have anything different from the old one other than red rear wheel rims?
11. How does the new CBZ extreme spin about two axes in one jump?

Enough? Really, you people ought to be banned for the mental trauma your rubbish adverts cause to billions of innocent people. On another note, the people at TVS who dreamed of 'jab angoothe se kaam chale to laath kyon maarna?' for the self started TVS Star are snickering at you about now. You should be ashamed.

For the lucky uninitiated, here you go:
http://in.youtube.com/watch?v=i0ZhYYSrf_8