Thursday, April 12, 2007

Japanese Prof. Dr. M. Kubo & IOE prof. Dr. S.R. Joshi's Suggestions,

its time about 4:35 PM wednesday, 11th april 2007 at staff conference room of IOE computer department where we always take masters class. unexpectedly my prof. Dr. Joshi came up with japanese prof. Dr. Kubo. unfortunately i am little late in the class though profs. didnt start class yet. Dr. Kubo did Ph. D. from Sofia University japan and he established "Kubo Institute of Science & Technology" as far as i know from him. He did his Ph.D. in physics though he is interested in IT and computer science.

we students were late on this class. so our prof. Joshi so angried with us. i think its obvious. we have to respect our proffessors as he teach us for us and brought profesors from several countries to make a visit to us. i have never seen such more professors in IOE who is doing for Institute, students and country except Dr. Joshi. i am really glad. lets summarize what these two professors suggested us:

summary words: TIME,Philosophy,Laborious,Domain Knowledge,Morality,Entertainment,do 4 Country.

Dr. Kubo wrote that TIME=>CHANCE. he is about 65 yrs old though he is so energetic in knowledge sharing. Definitely we have to know the TIME. we have to play with TIME so we can grab the oppertunities. we have several oppertunities on our hand. both professors suggested that every body must be responsible in his DUTY. though except duty, of course he has time for family and entertainment that is also the most necessary part. he said "never sell your morality, its the most important, expand knowledge in everyfield as possible as you can, do entertainment at the time of entertainment, so its not bad having girl friend ha ha ha ...he laughed." i am so impressed by such a friendly professor that every body must be like that. some time he angried with us saying that "you late commer, i hate late commer, be in time, time is the important".

if IOE has several such professors, what will be the status of IOE?? its only imagination till now.

Last Monday, Prof. Joshi came up with Prof. Kubo in CIT, IOE. as i knew that Prof. Kubo want to promote IT industry in Nepal. it was a good oppertunity for me to show the IT infrastructure of IOE but unfortunately Internet link from NTC was down on that day having Optical Link problem from NTC. Dr. Kubo just tried to show about his profile and IT infrastructure of his institute. Sorry!!! Prof. Kubo as net was down on that day. any way i saw your profile on the next day from so impressing.

any way, its a nice interaction having such professors with us in the class.

Sunday, April 08, 2007

How does a laser speed gun work to measure a car's speed?

Laser (or lidar, for light detection and ranging) speed guns use a more direct method that relies on the reflection time of light rather than doppler shift. You have probably experienced the reflection time of sound waves in the form of an echo. For example, if you shout down a well or across a canyon, the sound takes a noticeable amount of time to reach the bottom of the well and travel back to your ear. Sound travels at something like 1,000 feet (300 meters) per second, so a deep well or a wide canyon creates a very apparent round-trip time for the sound.

A laser speed gun measures the round-trip time for light to reach a car and reflect back. Light from a laser speed gun moves a lot faster than sound -- about 984,000,000 feet per second (300,000,000 meters), or roughly 1 foot (30 cm) per nanosecond. A laser speed gun shoots a very short burst of infrared laser light and then waits for it to reflect off the vehicle. The gun counts the number of nanoseconds it takes for the round trip, and by dividing by 2 it can calculate the distance to the car. If the gun takes 1,000 samples per second, it can compare the change in distance between samples and calculate the speed of the car. By taking several hundred samples over the course of a third of a second or so, the accuracy can be very high.

The advantage of a laser speed gun (for the police anyway) is that the size of the "cone" of light that the gun emits is very small, even at a range like 1,000 feet (300 meters). The cone at this distance might be 3 feet (1 meter) in diameter. This allows the gun to target a specific vehicle. A laser speed gun is also very accurate. The disadvantage is that the officer has to aim a laser speed gun -- normal police radar with a broad radar beam can detect doppler shift without aiming.

For more information, check out How Radar Detectors Work.