Today, the biggest passenger aircraft has ever been made in history is making its first test flight from Frankfurt to New York. The test flight is supposedly to test air conditioning system, entertainment electronics and other comfortibilities. Most of the passengers are Airbus employees and reporters. They will be asked to give feedback about the performance during the flight.
I am always amazed with how sophisticated the aeronautics is. First, how could a pair of wings lift such a massive body of an airplane? The material used on the wings must be superstrong and must be precisely and carefully selected and the superconstruction must be very detail and thoroughly. Just look at how much weight they have to bear. Gas tank is resided there, four huge jet enginees hang there too. Not to mention the body (in case of A380, with no passengers it weights 252 tons).
The wheels are also very strong. If we look at how tiny the rods that holding the wheel, we can imagine what a pressure it has to support. As we know, pressure (P) is defined as Force divided by crossection of an area. If the area is small relative to the force, the pressure becomes higher. There is 3 wheel system on most airplanes. One is in the front, the other two are below the wings. If there is 500 passengers with weight of 60 kg each passenger, there will be 30 ton in weight. Baggages can contribute to about the same amount. With other stuff packed into the aircraft (foods, etc.), the total weight can be up to 100 ton. So the total weight is about 352 ton. Assume the pressure is spread evenly to the three wheels. So each wheel bears about 120 tons!
The wing is even more astounding. The span for for A380 is about 78 meters. With such a long span (of two wings), it has to bear massive load. If we look back to high school physics 101, the torc (or torque) is defined as a product of force times length. It is also called Moment of the Force. While flying, these wings experience constant vibration and shock, either from turbulence or others.
The last thing I am also wondered is its avionics, including its control system. With such a complex system, ofcourse we need to have very complex instrumentation and control system too. I recalled when I was still in college, in one of courses I took was Control System Theory and Digital Control System. Those courses made me got big headache. Lots of math involved: Fourier, Laplace, z-transform; higher level integral and differential (including differential equations), etc. Not only that, an aircraft has strict restrictions on how to carry weight. So engineers have to design and decide what materials and components to fit in the plane.
The last but not least, aircraft is one of the top-most and top-notch of all advancements and product of engineering and technolgy humans have ever invented.
Monday, March 19, 2007
Friday, February 2, 2007
Cheap Long Distance Calls
My friend pointed me to Google map that has a cool feature: phone call forwarder. The way it work is that after you find a company or any contact/address information with phone number on the left side of the map, we click "call" link on the right of the phone number. A textbox will appear asking us to enter our phone number. Once we enter our own phone number and press "call", our phone will ring. Interestingly, when I tried it, I got call from the destination which I was calling to. When I picked up, I heard voice "connecting.." and then a dialing tone was heard. I guess, if there was somebody had picked up my call, I would made a call.
In this case, Google VOIP gateway intermediates connection from my phone to the destination. Google makes two connections, one is to my phone and second, to the destination (both originating from Google).
This way, we can make free long distance calls!
In this case, Google VOIP gateway intermediates connection from my phone to the destination. Google makes two connections, one is to my phone and second, to the destination (both originating from Google).
This way, we can make free long distance calls!
My Dream Energy Generator
I have been dreaming if there is a way to generate power from water. This dream power generator will just convert water to electrical power with Oxigen as its residue.
This technology shall be cheap to make and compact enough to fit into a car. I imagine till will reverse global warming effect. Why? because, first, it takes water from sea to generate energy. Secondly, it does not generate much pollutant to the ozone layer. Third, it generates oxigen essensial to human.
That's just (all will stay) as my imaginary dream, eventhough with fusion we could similarly do create energy from oxigen, but the technology is still far from practical use.
This technology shall be cheap to make and compact enough to fit into a car. I imagine till will reverse global warming effect. Why? because, first, it takes water from sea to generate energy. Secondly, it does not generate much pollutant to the ozone layer. Third, it generates oxigen essensial to human.
That's just (all will stay) as my imaginary dream, eventhough with fusion we could similarly do create energy from oxigen, but the technology is still far from practical use.
Thursday, February 1, 2007
45 nm Chips
Last week Intel announced that they had overcome difficulties in making transistors smaller and smaller. A separate announcement was also made by IBM.
I don't know if both companies have the same solution for the nano technology. We'll see.
I don't know if both companies have the same solution for the nano technology. We'll see.
Sunday, January 28, 2007
Friday, January 26, 2007
Review on Sandisk's Sansa e280 MP3 Player
I got my player a few weeks ago after going through rigorous reviews posted by other users on the Internet. My decision to buy this one instead of iPod was mainly because Sansa is more open system than Apple's iPod. Also, I recalled that MaximumPC sometime ago had reviewed and made comparison between some audio formats and Real's Rhapsody audio format (*.rax) is superior than others, including Apple's AAC (*.m4p or *.m4a).
Another reason is that Rhapsody has monthly rental service plan, which allows you to listen to their files (yes, all of them which is millions of music files) on the go (on Sansa players) or through its Rhapsody software running on PC. They even allow us to indirectly transcode the files to non-DRM MP3 or WMA format. How, you may ask? It is by burning your purchased music files and then re-rip them to unprotected MP3 or WMA. The quality of this *.rax files are really good and the size is not bigger than average high quality MP3 encoded in VBR.
One thing I don't like from Sansa is the buttons on the front. The four buttons surrounding the rotating wheel are placed sunken (shallow) than the wheel hence make them harder to reach/to push.
Quality of the sound is average. Sometimes I hear some distortion, but not sure whether this is caused by the device itself or because the music was undersampled/bad encoder.
Will continue in more detail if time permits.
Another reason is that Rhapsody has monthly rental service plan, which allows you to listen to their files (yes, all of them which is millions of music files) on the go (on Sansa players) or through its Rhapsody software running on PC. They even allow us to indirectly transcode the files to non-DRM MP3 or WMA format. How, you may ask? It is by burning your purchased music files and then re-rip them to unprotected MP3 or WMA. The quality of this *.rax files are really good and the size is not bigger than average high quality MP3 encoded in VBR.
One thing I don't like from Sansa is the buttons on the front. The four buttons surrounding the rotating wheel are placed sunken (shallow) than the wheel hence make them harder to reach/to push.
Quality of the sound is average. Sometimes I hear some distortion, but not sure whether this is caused by the device itself or because the music was undersampled/bad encoder.
Will continue in more detail if time permits.
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