Rezaf Diary

I'll write about my daily life, as a PhD Student at the University of Illinois. I'll put some photos from my town, Urbana, and some music.

Monday, February 19, 2007

My new cell will make me feel like a president

I bought a new treo 680 cell phone on the president day, so I'll be feeling like a president from now on. I'm still waiting for my newly bought treo to come in a few days, but I've been using a Nokia smartphone for a 3 years now. With my Mp3 Player in a pocket and Palm Zire organizer in another (and the big chunky Nokia in a third) I felt like anybody excpet an executive!

So, how my treo is supposed to make me feel like a president? First of all it's going to eliminate three humps on my pants! With a leather case on my belt and my trousers finally fitting on me, I'll definitely LOOK more like an executive.

Then whenever I pull my treo out, I'll feel as exclusive as a president, cause I went through all the troubles to get an exclusive arctic white treo. Not a bland grey or silver, but the absolutely great looking white one!

Aside from aesthetics, I've been relying on my Palm to organize my life for a long time now (my first Palm was an m105 back in 2001, and I never felt OK with the Symbian. Stylus rocks!). I simply can't live without my calendar, and the occasional missing of an appointment due to my laziness (of finding in which pocket I've put my Palm) or bad luck (oops, I forgot to bring the Palm!) should totally vanish with my treo.

I'm going to set my three different email accounts to be popped automatically on my treo, so no more running back and forth between my office and seminar rooms. I'm still a (grad) student, and it would be nice if I can get my emails in the classrooms or seminars too.

Let's see, so many times I had to prepare a PowerPoint presentation in 20 minutes because a professor just decided to visit our group! Yep, treo can do that too! I write reports and papers a lot, so maybe the Microsoft word compatibility can help me sometimes, although I confess the cramped keyboard hinders fast typing. Well, we live in a world of compromises, right?!

Let's not forget about listening to 8 giga bytes of MP3 (treos now accept SDHC cards, and they're cheap!). No more Ipod! Oh, let's not forget the Nintendo emulator software! Mario, where are you?! (See, us Gen. Nintendo kids have to keep Mario near). Life of a president is not all about work after all, even a president needs some entertainment once in a while - ask Bill Clinton about it!

Oh, and let's not forget I can SSH into my home Linux server using pssh. This one rocks!

The fact that there are thousands of third party apps to choose from (for cheap of coarse!) and my ability to write Java programs for my treo is just the icing on the cake!

Note: Click on the photos to enlarge them.

If you feel interested in any of them and want to get the original file, please don't hesitate to email me!

Saturday, February 17, 2007

The cars I would like to get

Acura TL or RL
Mercedes C280 luxuary or an E class
Lexus IS 350
Lexus GS 350
Audi A4
Cadillac CTS

BUT, I'm pretty happy about my Honda Accord, it's awesome!

Note: Click on the photos to enlarge them.

If you feel interested in any of them and want to get the original file, please don't hesitate to email me!

Tuesday, February 13, 2007

Palm is screwing up its users

Ok, I'm feeling angry and upset! I finally made up my mind to pay $400 and buy this new cell phone, Palm treo 680 in arctic white color (The second phone from right in this picture). I believe it's much more interesting than the bland graphite version (First one from left). I decided to go and buy it on Wednesday last week, and I checked the Palm website to make sure they have it. Yep, they had it.

Now, on Friday I took my credit card and went to their web store to buy what I've been craving for the last month. But,.... it's not there! To be more exact, they only had the graphite version up on their website! It turned out that Cingular has bought all color treo 680s for itself, and it seems that their deal gives the exclusive rights of color treo 680s to CIngular. So, Palm just decided to screw their customers who are not on Cingular, like me. Now my only option is the dull gray (graphite) one. BOOOH!

Listen Palm, I use T-mobile, and I was going to add $400 of my hard earned money to your pockets. NOT ANY MORE! Unless you give me an arctic treo 680, I'm not going to get one! Are you listening Palm?! You screw your loyal customers (I've been having Palm devices since 2001. This makes me a 6-year loyal Palm customer), YOU GET OUT OF BUSINESS!

Take a look at these photos too and see for yourself why I want the arctic color! (The two following pictures are copyrighted images taken from engadet website.)

Note: Click on the photos to enlarge them.

If you feel interested in any of them and want to get the original file, please don't hesitate to email me!

Sunday, February 04, 2007

Open loop vs closed loop control

Do you ever wonder what the hell is a closed loop control system? How doews it differ from an open loop control system? If so, read on!

Theoretically, an open loop control system should be able to do whatever their closed loop counter parts do. All you need is a 100% accurate mathematical model of your system, and every other environmental factor which could affect the systems operation.

Ok, we want to control real stuff. In reality you can never model a system accurately 100% (it is just too hard!) , and it's even harder to account for environmental factors (or noise if you like). Thus you see a good amount of deviation from what you modeled in your real implementation.

How does a feedback control system work? It doesn't care about the internals of the system, just looks at it as a black box. It will look at the outputs of the system and will say: "hm... I'd like the output to be 10, but it is 8, so let's increase the input a bit. ok, now it's better, we're getting to 10... oh oh , we passed 10 and are now at 10.5, oh boy, let's decrease the input a bit. Ok, that's better, output is at 10 now, I'm done! But I'll keep an eye on the output in case an unknown noise comes in, in which case I can compensate for it by changing the input."

Now the problem with the feedback control is that since our systems are real (the tech word is causal) and our controller cannot foresee the future (DUH, we're talking about real world!) and moreover it doesn't know that much about the system internals and noise, We
will usually have overshoot (like the scenario I told you, i.e. we want 10, but for a short period we get 10.5) and oscillation (like 8...9...10...10.5...9.75...10.... unless you set your feedback controller to work really slow.

So to sum it up, open loop should work fine and beautifully, but only in your dreams! put an open loop controller before a real system, and you'll see deviations, which the controller cannot even correct. In real world we use feedback control systems all the time.

As an interesting side note, our brain controls our limbs in a feedback control system, which is set to overshoot and oscillate a bit for fast responses. Check it out: stretch your right arm, and then try to quickly bring your palm in front of your face, and stop it there. You'll surely see the overshoot and oscillation!

Note: Click on the photos to enlarge them.

If you feel interested in any of them and want to get the original file, please don't hesitate to email me!