Saturday, 23 August 2008

Wireless Power System

Intel on Thursday showed off a wireless electric power system that analysts say could revolutionize modern life by freeing devices from transformers and wall outlets.

Intel chief technology officer Justin Rattner demonstrated a Wireless Energy Resonant Link as he spoke at the California firm's annual developers forum in San Francisco.

Electricity was sent wirelessly to a lamp on stage, lighting a 60 watt bulb that uses more power than a typical laptop computer.

Most importantly, the electricity was transmitted without zapping anything or anyone that got between the sending and receiving units.

"The trick with wireless power is not can you do it; it's can you do it safely and efficiently," Intel researcher Josh Smith said in an online video explaining the breakthrough.

"It turns out the human body is not affected by magnetic fields; it is affected by elective fields. So what we are doing is transmitting energy using the magnetic field not the electric field."

Examples of potential applications include airports, offices or other buildings that could be rigged to supply power to laptops, mobile telephones or other devices toted into them.

The technology could also be built into plugged in computer components, such as monitors, to enable them to broadcast power to devices left on desks or carried into rooms, according to Smith.

"Initially it eliminates chargers and eventually it eliminates batteries all together," analyst Rob Enderle of Enderle Group said of Intel's wireless power system.

"That is potentially a world changing event. This is the closest we've had to something being commercially available in this class."

Previous wireless power systems consisted basically of firing lightning bolts from sending to receiving units.

Smith says Intel's wireless power system is still in an early stage of development and much research remains before it can be brought to market.

Rattner spoke of technological transformations he expects by the year 2050.

"You'd like to cut the last cord," Smith said.

"It's great that we have wireless email and wireless internet and stuff like that but at the end of the day it would be nice to have wireless recharge as well."

Source:Yahoo News/AFP
Contributed by: Sriram Venkitachalam

Author Comment: Having graduated with majors in Electrical Engineering, this event is special.


Saturday, 28 June 2008

Chip-kaalee!

It was around 8:30pm when a fast local to Badlapur arrived at platform number five of Thane station. A huge crowd of commuters were moving along the staircases at the time. Suddenly a loud cry, "Bachao,bachao!" baffled commuters and people started pushing one another on the staircases. Rahul Surve, a Thane resident, who was on the staircase at the CST end, said, "I was in the middle of thhe packed staircase when suddenly, all the women in the platform started shouting. Everyone, unware of the situation, started running up and out of the station....In a moment, the entire platform was empty of commuters. There wasn''t single person on it"

Jaikishen Gupta, an employee of a canteen located on the platform said, "we quickly pulled down our shutters,as we thought some kind of emergency had gripped the station". Some commuters on the platform jumped onto the tracks and a few unfortunate even fell into open drains between platforms.

Meanwhile, some commuters informed the government railway police about the commotion... the police could not fanthom what caused the panic and kept running from one platform to another, carrying a stretcher with them..assuming there was an accident".

When the police conducted an enquiry, the reason for the commotion completely baffled them. ..." It was a middle-aged woman who had shouted for help when a lizard (3 inches in length according to eye-witnesses!)fell on her from the roof of the train. people did not understand why she was screaming and instead of helping her, started running. Fortunately no one was hurt!.


Source: excerpts from a report- "How a lizard held Thane station to ransom",Mumbai Mirror edition-28th june 2008

Blog author's conclusion-railway officials should immediatly nab the accused "chip-kaalee" and charge fines for illegal travel on the roof of a train!..and the lady in this case should be recommeded for an award of the highest order for her "bravery in saving lives" of fellow commuters.

Sunday, 22 June 2008

The secretary problem

The secretary problem is an optimal stopping problem that has been studied extensively in the fields of applied probability, statistics, and decision theory. It is also known as the marriage problem, the sultan's dowry problem, the fussy suitor problem, and the best choice problem. The problem can be stated as follows:

  1. There is a single secretarial position to fill.
  2. There are n applicants for the position, and the value of n is known.
  3. The applicants can be ranked from best to worst with no ties.
  4. The applicants are interviewed sequentially in a random order, with each order being equally likely.
  5. After each interview, the applicant is accepted or rejected.
  6. The decision to accept or reject an applicant can be based only on the relative ranks of the applicants interviewed so far.
  7. Rejected applicants cannot be recalled.
  8. The object is to select the best applicant. The payoff is 1 for the best applicant and zero otherwise.

Let us say that an applicant is a candidate only if it is better than all the applicants viewed previously. Clearly, since the objective in the problem is to select the single best applicant, only candidates will be considered for acceptance. One reason why the secretary problem has received so much attention is that the optimal policy for the problem (the stopping rule) has a surprising feature. Specifically, for large n the optimal policy is to skip the first n / e applicants (where e is the base of the natural logarithm) and then to accept the next candidate that is better than all those previously interviewed. As n gets larger, the probability of selecting the best applicant from the pool goes to 1 / e, which is around 37%. Whether one is searching through 100 or 100,000,000 applicants, the optimal policy will select the single best one about 37% of the time.

For an arbitrary cutoff r, the probability that the best applicant is selected is

P(r)=\sum_{j=r}^{n}\left(\frac{1}{n}\right)\left(\frac{r-1}{j-1}\right)=\left(\frac{r-1}{n}\right)\sum_{j=r}^{n}\left(\frac{1}{j-1}\right).

Letting n tend to infinity, writing x as the limit of r / n, using t for j / n and dt for 1 / n, the sum can be approximated by the integral

P(r)=x \int_{x}^{1}\left(\frac{1}{t}\right)dt = -x \text{log}(x).

Taking the derivative of P(r) with respect to x, setting it to 0, and solving for x, we find that the optimal x is equal to 1 / e. Thus, the optimal cutoff tends to n / e as n increases, and the best applicant is selected with probability 1 / e.

In summary:

Psychologists and experimental economists have studied the decision behavior of actual people in secretary problems . In large part, this work has shown that people tend to stop searching too soon. This may be explained, at least in part, by the cost of evaluating candidates. Extrapolating to real world settings, this might suggest that people do not search enough whenever they are faced with problems where the decision alternatives are encountered sequentially. For example, when trying to decide at which gas station to stop for gas, people might not search enough before stopping. If true, then they would tend to pay more for gas than they might had they searched longer. The same may be true when people search online for airline tickets, say. Experimental research on problems such as the secretary problem is sometimes referred to as behavioral operations research.

source: From Wikipedia, the free encyclopedia
related site:http://utilitymill.com/utility/Secretary_Problem_Optimizer







Saturday, 14 June 2008

A temple cave


Batu Caves, Malaysia

Picture taken by: C.K.Venkataraman Reference:http://en.wikipedia.org/wiki/Batu_Caves

Sunday, 8 June 2008

Time!...for game,set and match


The All England Lawn Tennis Club's-
WIMBLEDON
Championships 2008
23 June- 8 July

ROLEX-The official time-keepers for a timeless event