Saturday, January 19, 2008
The auto industry, especially companies that make fast sports cars, is starting to use the same materials out of which airplanes are manufactured. Carbon fiber and fiberglass composites, used for wings and other structural elements on planes, can help make the bodies of cars stronger and lighter at the same time. This means faster performance (because of less weight) and better crash safety.
Lamborghini also claims that the Reventon is the most powerful -- and the most expensive -- model it's made yet.o.0? Let's take a peek...
Wow? So freaking cool...i want!!!rawr...
♥ I'm listening.
12:30:00 PM
Monday, January 14, 2008
guys. sorry ah. but i have problem uploading the information i want to upload. So, i'm using another one.
The ABS System
The theory behind anti-lock brakes is simple. A skidding wheel (where the tire contact patch is sliding relative to the road) has less traction than a non-skidding wheel. If you have been stuck on ice, you know that if your wheels are spinning you have no traction. This is because the contact patch is sliding relative to the ice. By keeping the wheels from skidding while you slow down, anti-lock brakes benefit you in two ways: You'll stop faster, and you'll be able to steer
while you stop.
There are four main components to an ABS system:
Speed sensors
Pump
Valves
Controller
Photo courtesy -->Anti-lock brake pump and valves
Speed Sensors
The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential
, provide this information.
Valves
There is a valve in the brake line of each brake
controlled by the ABS. On some systems, the valve has three positions:
In position one, the valve is open; pressure from the master cylinder
is passed right through to the brake.
In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder.
In position three, the valve releases some of the pressure from the brake.
Pump
Since the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.
Controller
The controller is a computer in the car. It watches the speed sensors and controls the valves.
ABS at Work
There are many different variations and control algorithms for ABS systems. We will discuss how one of the simpler systems works.
The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 kph) under ideal conditions, but a wheel that locks up could stop spinning in less than a second.
The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire
can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power.
When the ABS system is in operation you will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. Some ABS systems can cycle up to 15 times per second.
How cool is that?
ANSWER: TOTALLY.
:D signing off, xunbin.
♥ I'm listening.
7:47:00 PM
Saturday, January 12, 2008
Gears are used in tons of mechanical devices. They do several important jobs, but most important, they provide a gear reduction in motorized equipment. This is key because, often, a small motor spinning very fast can provide enough power
for a device, but not enough torgue
. For instance, an electric screwdriver has a very large gear reduction because it needs lots of torque to turn screws, but the motor only produces a small amount of torque at a high speed. With a gear reduction, the output speed can be reduced while the torque is increased.
Another thing gears do is adjust the direction of rotation. For instance, in the differential between the rear wheels of your car, the power is transmitted by a shaft that runs down the center of the car, and the differential has to turn that power 90 degrees to apply it to the wheels.
There are a lot of intricacies in the different types of gears too.
:D on schedule...
♥ I'm listening.
9:51:00 AM
Monday, January 7, 2008
How Bluetooth
A number of devices that you use to take advantage of this same radio-frequency band
. Baby monitors
, garage-door openers and the newest generation of cordless phones
all make use of frequencies in the ISM band. Making sure that Bluetooth and these other devices don't interfere with one another has been a crucial part of the design process.
One of the ways Bluetooth devices avoid interfering with other systems is by sending out very weak signals of about 1 milliwatt. By comparison, the most powerful cell phones can transmit a signal of 3 watts. The low power limits the range of a Bluetooth device to about 10 meters (32 feet), cutting the chances of interference between your computer system and your portable telephone or television. Even with the low power, Bluetooth doesn't require line of sight between communicating devices. The walls in your house won't stop a Bluetooth signal, making the standard useful for controlling several devices in different rooms.
Bluetooth can connect up to eight devices simultaneously. With all of those devices in the same 10-meter (32-foot) radius, you might think they'd interfere with one another, but it's unlikely. Bluetooth uses a technique called spread-spectrum frequency hopping that makes it rare for more than one device to be transmitting on the same frequency at the same time. In this technique, a device will use 79 individual, randomly chosen frequencies within a designated range, changing from one to another on a regular basis. In the case of Bluetooth, the transmitters change frequencies 1,600 times every second, meaning that more devices can make full use of a limited slice of the radio spectrum. Since every Bluetooth transmitter uses spread-spectrum transmitting automatically, it’s unlikely that two transmitters will be on the same frequency at the same time. This same technique minimizes the risk that portable phones or baby monitors will disrupt Bluetooth devices, since any interference on a particular frequency will last only a tiny fraction of a second.
When Bluetooth-capable devices come within range of one another, an electronic conversation takes place to determine whether they have data to share or whether one needs to control the other. The user doesn't have to press a button or give a command -- the electronic conversation happens automatically. Once the conversation has occurred, the devices -- whether they're part of a computer system or a stereo -- form a network. Bluetooth systems create a personal-area network (PAN), or piconet, that may fill a room or may encompass no more distance than that between the cell phone on a belt-clip and the headset on your head. Once a piconet is established, the members randomly hop frequencies in unison so they stay in touch with one another and avoid other piconets that may be operating in the same room.
Bluetooth is useful...
^^ END.
I'm on schedule....wheee~~~
♥ I'm listening.
4:57:00 PM
Sunday, January 6, 2008
Ipod
People buy it because:
It's slim
Funky looking
Easy to use
Easy to navigate
kinda cool eh? but let's look at the insides of an ipod...
♥ I'm listening.
4:02:00 PM
Cameras!
^^
today randomly surfing AGAIN!^^
let's take a peek at today's treasure.
2 types of camera-
SLR cameras
point-and-shoot cameras
This is the "organs" of a SLR camera.^^
These are the "procedures" a camera take to shoot a picture.^^
1.when you click the shutter button, the camera quickly switches the mirror out of the way
2.screen turns black because the light is directed to the exposed film
In this sort of camera, the mirror and the translucent screen are set up so they present the real image exactly as it will appear on the film. The advantage of this design is that you can adjust the focus and compose the scene so you get exactly the picture you want. For this reason, professional photographers typically use SLR cameras.
cameras are built with both manual and automatic controls, and most point-and-shoot cameras are fully automatic. Conceptually, automatic cameras are pretty much the same as fully manual models, but everything is controlled by a central microprocessor instead of the user. The central microprocessor receives information from the autofocus system and the light meter. Then it activates several small motors, which adjust the lens and open and close the "thing covering the lenses of a camera"
Very Advanced and chim...TT
I understand most parts la. but some i very blur so copy one SMALL bit. cher, don't scold me
♥ I'm listening.
3:48:00 PM
Saturday, January 5, 2008
aiya. now i keep randomly surfing and keep finding things useful for dnt...ahaha
Data Storage devices.
They can be stored in devices virtually in any forms of energy.
The devices can be either stored in an analog or digital format on the devices(medium)
Any input or output equipment may be considered data storage equipment if it writes to and reads from a data storage medium. Data storage equipment uses either:
easily replaced
methods requiring mechanical disassembly tools
loss of memory if disconnected from the unit.
One of the most common mediums are----USB Flash Drives!!!
"Characteristics" of a USB Flash Drives aka Thumbdrives-
Light, Small, Portable, Rewritable, Uses USB port 2.0 the fastest USB port so far, Uses less power than Floppy disks and such, security is better than most other mediums too.
They also come in many different designs...^^
♥ I'm listening.
12:32:00 PM
