|SCIENCE & TECHNOLOGY||Thursday, October 9, 2003, Chandigarh, India|
the size of a grain of sand
from New York blackout
Blackout in USA and Canada on August 14 came as an unbelievable surprise to the rest of the world. Such a massive power failure in these countries, especially in the US, known to be most advanced, was least expected. What proved to be more baffling was the fact that the blackout continued for 13 long hours in New York, for 24 hours in some parts and even for 48 hours in other parts. It was natural to think and link it with terrorism but this apprehension was soon ruled out.
Life was thrown completely out of gear in the affected parts of two countries. Fifty million people of eight states of the US and South East Canada were affected. New York, Detroit, Michigan, Cleveland, Ottawa, Toronto and Ohio were the major stations that suffered. The power failure led to shutting down of more than 100 power plants in the US and Canada, 22 of them nuclear. The New York subway system collapsed, train services were in a mess, escalators stopped, elevators stopped, Gas supply was badly affected, taps became dry. Flights were cancelled, looting incidents came to the fore and bus terminals were closed. Not only this, the US President had to release a message to the nation !
Looking into the finer details, stock exchanges were closed, ATMs were non-operational, traffic lights went off, traffic was in chaos, three major airports of New York plunged into complete darkness and people were asked to stay back home and to avoid coming to their work places. Power had shown its power !
The cause of power failure was not immediately known. Overloading of power grid was later ascertained as the reason behind it. The problem started in Lake Erie loop encircling Lake Erie from New York to Detroit into Ontario, Canada and then back to New York. About 300 MW of power moving East in the Northern leg of the loop suddenly reversed and started moving West causing a chain of failures in just nine seconds as the fire walls provided to prevent such a chain reaction failed.
Well, the power failure stands tackled now and the life that came to grinding halt in the US and Canada has become normal. The US has turned to India to seek advice over management of blackouts. And the incident has left the world brooding. What measures need to be taken to prevent such an incident and what to do if it happens, the world is thinking. Following are the lessons that we can draw from the massive power failure:
* Overloading of grids must be avoided under all circumstances. This lesson seems quite obvious but needs strict implementation.
* Relying on full automation can be dangerous. Provision of full automation may be made but it must be backed up by manual supervision.
* Automatic shutdown of power plants must be provided to protect them against power surges. This provision prevented damage to more than 100 power plants in the US and Canada.
* Transmission of high voltage electricity over long distances may prove dangerous. Wherever provided, it must be made fully reliable.
* Alternate backup power system for essential services should always be there. Elevators need to be given top priority followed by water supply system.
* Emergency procedures to evacuate people from elevators and subways must exist and should work well when the need arises.
* As cellphones are now becoming an integral part of human life, cell phone operators must take lesson and keep adequate power backup arrangement in their cellular stations. Cell phone system in the US broke down very soon as people frantically tried to talk to one another and overloaded the system.
* Traditional landline phone system, now being phased out slowly, should not be done away with completely as it is run on large banks of batteries and can keep working for several hours even without power supply.
* A major segment of people in the US couldnít use even landline phones as they had maintained only cordless phone sets in their apartments. Thus provision of dial up phones with attached receivers should be maintained.
* Laptops worked well for the surfers and Internet was the hero of the day as it provided up-to-date information to the people. However, with the failure of cellphones, many of the laptops could not operate. Thus internet plus landline phone emerged as the best combination to follow.
* Another lesson that the administration of the affected parts learnt was to keep law and order situation under control as bad elements took advantage of the situation and indulged in looting people.
* The US and Canada stayed cool and swiftly took the situation under control. Initial panic created by pitch darkness as people bumped into each other, died soon. It should serve as an example to other countries.
Lastly, what could happen when
everything is put on electricity must be realised. In the US, even the
use of manual typewriters and preparing reports in longhand made news.
Such is the extent of modernisation. India, habitual of facing power
cuts was looked upon for advice. Another lesson is learnt here.
Standby arrangements must be given due attention as the world
automates and modernises itself more and more.
Robots the size of a grain of sand
Chemists at the University of California, San Diego have developed minute grains of silicon that spontaneously assemble, orient and sense their local environment, a first step toward the development of robots the size of sand grains that could be used in medicine, bioterrorism surveillance and pollution monitoring.
In a paper to be published in September in the Proceedings of the National Academy of Sciences, which will appear in the journalís early on-line edition this week, Michael Sailor, a professor of chemistry and biochemistry at UCSD, and Jamie Link, a graduate student in his laboratory, report the design and synthesis of tiny silicon chips, or "smart dust," which consist of two colored mirrors, green on one side and red on the other. Each mirrored surface is modified to find and stick to a desired target, and to adjust its color slightly to let the observer know what it has found.
"This is a key development in what we hope will one day make possible the development of robots the size of a grain of sand," Sailor explains. "The vision is to build miniature devices that can move with ease through a tiny environment, such as a vein or an artery, to specific targets, then locate and detect chemical or biological compounds and report this information to the outside world. Such devices could be used to monitor the purity of drinking or sea water, to detect hazardous chemical or biological agents in the air or even to locate and destroy tumour cells in the body."
To create the smart dust, the researchers use chemicals to etch one side of a silicon chip, similar to the chips used in computers, generating a colored mirrored surface with tiny pores. They make this porous surface water repellent, or hydrophobic, by allowing a chemical that is hydrophobic to bind to it. They then etch the other side of the chip to create a porous reflective surface of a different colour and expose the surface to air so that it becomes hydrophilic, or attractive to water.
Using vibrations, they can break the chip into tiny pieces, each about the size of the diameter of a human hair. Each piece is now a tiny sensor with opposite surfaces that are different colours, with one attracted to water and one repelled by water and attracted to oily substances.
When added to water, the "dust" will align with the hydrophilic side facing the surface of the water and the hydrophobic side facing toward the air. If a drop of an oily substance is added to the water, the dust surrounds the drop with the hydrophobic side facing inward. In addition to this alignment, which will occur in the presence of any substance that is insoluble in water, a slight colour change occurs in the hydrophobic mirror. The degree of this colour change depends on the identity of the insoluble substance. The colour change occurs as some of the oily liquid enters the tiny pores on the hydrophobic side of the silicon particle.
"As the particle comes in contact with the oil drop, some of the liquid from the target is absorbed into it," Sailor explains. "The liquid only wicks into the regions of the particle that have been modified chemically. The presence of the liquid in the pores causes a predictable change in the colour code, signaling to the outside observer that the correct target has been located."
The hydrophilic side of the chip behaves in a similar way; it changes colour according to the identity of the hydrophilic liquid it contacts. While each individual particle is too small to observe the color code, the collective behavior of the particles facilitates the detection of the signal.
This research effort, funded by the National Science Foundation and the Air Force Office of Scientific Research, builds on previous work by the Sailor group to develop various types of sensing devices from silicon chips. A year ago, the group reported the development of silicon particles with a single sensing surface.
Link, the first author on the paper,
says the dual-sided particles have the additional benefit of being
able to collect at a target and then self-assemble into a larger, more
visible reflector that can be seen from a distance. "The
collective signal from this aggregate of hundreds or thousands of tiny
mirrors is much stronger and more easily detected than that from a
single mirror," she points out. "The tendency of these
particles to clump together will therefore enable us to use this
technology for remote sensing applications." ó University
Take special care of position of reinforcement in cantilever slabs. In cantilever slabs, steel must be at the top face and not at the bottom as in normal slab. Bottom steel coming from main slab to the cantilevers must be cranked up to remain at top and steel chairs made of small bar lengths should be provided below it to support it. Take care that labour movement does not settle the steel from top to middle or bottom. If it happens, Cantilever slab or chajja will fail and fall down removal of shuttering or sometime later.
* * *
Avoid use of bricks in roof slab construction. Masons often advocate this type of slabs.
Technically, these slabs are porous, weak and invite leakage problems at a later stage.
Efflorescence is another problem in these. As the bricks are laid on edge, these prove thicker, heavier and costly.
Always go for a RCC roof slab. Use proper grade of cement, employ skilled labour and leave proper expansion joints at slab ends to eliminate hair cracks often associated with RCC slabs. Instead of following thumb rules, hire the services of an engineer to design the slab.
He will bring savings in steel and slab thickness.
* * *
Use coarse sand in construction, specially in all of RCC, plain concrete and flooring work. Coarse sand adds to the strength. Even in plaster work, if coarse sand is mixed with fine sand, better and easy finish is achieved.
You must check the sand to be free of clay lumps Unload it on firm ground to avoid mixing of clay.
Look for a good source of sand. In case of
rivers, coarse sand is available near the inner edge of the meander. In canals,
it is available near the falls. Be particular about this and insist on sand
from these particular points.
Artificial muscles may someday upstage the world heavyweights of wrestling in a championship arm-wrestling match.
This science fiction scenario might
become a reality as the current trend continues toward developing
artificial muscles for robots that appear and behave like humans or
animals. Scientists and engineers worldwide are focusing on
biologically inspired technologies like artificial muscles and
intelligence. In the future, insect-like robots might relieve their
manufacturerís burden by packing themselves for shipping.
Intelligent robots might read books aloud, discuss stock options and
even replace dogs as manís best friend.
What is the difference between sleeping and unconscious state?
This is a question to which I am not able to give a detailed answer. I am not sure any one knows it fully. But a difference can be easily demarcated. When we are asleep our brain is given rest but only part of its functions are given a holiday. It is still on guard duty should a major need arise. Our pain and temperature sensing circuits are not shut down. If we are cold we snuggle deeper into the blanket. If we are warm we throw off the covers. Metabolism goes on. The food is digested. The memories and images are still stored in the brain but the manner in which they connect up and serialise is not under conscious control. This is the reason psychologists believe that analysis of dreams when the control of the conscious is weakened is a good way to understand the normally suppressed subconscious.
However when we are unconscious the control of senses is almost completely stopped. We still metabolise and breathe, but we cannot be woken up by a loud noise, a pinch or sprinkling of water on our face. Perhaps we do not dream either. There is a major circuit block in the brain. Unconsciousness follows a major trauma or metabolic malfunction. I feel that this is also designed to protect us from extreme pain and discomfort.
Would you please let me know the principle underlying the making of jalebees by our halwais?
I am sure that most skills and crafts like Jalebee-making did not follow the discovery of any principle. Actually it does not involve any special principle, but it is a clever discovery made by some grandmother a long time ago.
You must have seen that the dough pouring out of the hole in an earthen pot or a piece of cloth is rather wet and fluid. The halwai does on making the jalebee patterns with the out-flowing dough pouring into high temperature preheated oil or ghee in a karhai. The thin tube of dough becomes a little tough on the outside and is expanded by the steam generated inside the tube. The heated surface becomes brown, stiff and a bit porous. Quickly after that the pre-jalebees are transferred into another karhai containing hot syrup. The inside of the pre-jalebee is now ready to soak in the syrup and soon we have piping hot jalebees.
I am sure there are tricks in making the dough just right, but I would not know much about those.
Why do our eyes close during sneezing?
Let me try a commonsense
answer. It is clear that while sneezing our body is trying to expel air
through our nasal passages with an explosive force. In order to do that
all the muscles around our face are asked to fasten seat belts and
tighten up. No wonder then that the eyes are also closed shut. That is
what we do to our doors and windows before a hurricane strikes.
New products & discoveries
More efficient light bulbs
Thereís a gleam in electrical engineer Shawn Yu Linís eyes these days. Itís a reflection of yellowish light given off by a brightly glowing metallic flake inside a vacuum chamber. Heated to incandescence by an electric current, the metal sliver in Linís lab at Sandia National Laboratories in Albuquerque is made of tungsten, as is an ordinary light-bulb filament. But this experimental filament is markedly different from the delicate wires that light up homes and businesses. Electron-microscope imaging reveals the sliver as tiny tungsten rods, each less than one-hundredth the thickness of a human hair, neatly stacked in crisscross layers.
That perforated structure, designed and fabricated by Lin and his coworkers, makes the radiation shining from the rods remarkably intense. Whatís more, that intensity lies within an exceptionally narrow band of wavelengths compared with the emissions from ordinary heated tungsten.
This special quality of the emissions, recently recognised for the first time, has raised the prospect of important technological advances based on the new material. Among them may be incandescent lightbulbs many times more efficient than those available today.
The new material is a type of photonic crystal ó an orderly, periodic array of rods, pillars, or other structures that interacts with electromagnetic radiation in a special way. Using heated photonic crystals as radiation emitters is a new idea that Linís group is the first to try, says Eli Yablonovitch of the University of California, Los Angeles, a founder of the photonic-crystal field. "Itís very original," he says.
The emissionsí characteristics may
also have repercussions in fundamental physics. They apparently
contravene the century-old Planckís radiation law, one of the
pillars of scientific understanding of heat and radiation.
Consequently, many scientists have challenged the new findings.