Chandigarh, Thursday, March 18, 1999
 


Snow-bound areas and communication
by G.S. Dhillon
Activities on account of both civil and defence purposes in the high Himalayas i.e. snow-bound areas, have increased lately. Such activities require better and reliable communication facilities and they form a key component in the infrastructural development /defence of such areas.

Traffic jam has a solution
by Kalyan Ray
TRAFFIC snarl-ups may soon become a thing of the past with scientists designing a new computerised system to smoothen traffic condition. Intelligent transportation systems which may address problems inherent to current transportatation systems like road accidents and vehicular congestion are the trend of the day.

 

An exciting breakthrough
by T.M.S. Virdi
STORAGE Data Acceleration is a new technology developed by Western Digital that significantly improves the performance of removable media storage peripherals such as CDROM drives.

Science quiz New products & discoveries
 

Top



 

Snow-bound areas and communication
by G.S. Dhillon

Activities on account of both civil and defence purposes in the high Himalayas i.e. snow-bound areas, have increased lately. Such activities require better and reliable communication facilities and they form a key component in the infrastructural development /defence of such areas.

For working of the communication equipment, electric power is hard to get and the cost of extending a mains supply to a remote telecom site may be of the order of Rs. 4 lakh/km making it imperative to look at alternatives. The conventional diesel generators are difficult to operate in the remote areas with sub-zero temperatures. Of the nonconventional sources of the power, the wind power for working the Wind Generators also do not provide a feasible proposition as due to unsteady wind conditions with blizzards and snow storms occurring frequently. Also there is the additional problem of metallurgical failures in areas where winter temperatures can drop as low as -50C e.g. at Dras (Ladakh) the winter night temperatures have been reported to drop as low as -60C ! So the only option is to utilise stored power and look for the sunshine to produce electricity and charge the battery bank, which would meet the power requirements of the equipment.

SPV technology

This technology turns the sunlight into the electrical energy by using the SPV cells. The mode is non-polluting, having a high reliability and requires negligible maintenance. It also has the proven ability to provide near-continuous power in virtually all environments.

In the telecommunication industry the SPV applications are in the rural telephony, microwave/cell-phone/ radio-trunking repeaters, VHF/UHF radio base stations etc. For example, a “repeater station”in the Himalayan area would require 11.5 kwh daily to feed 10 amperes at 48 volts. The usual alternative of diesel generators would require two generators (one standby) of 3.5 kva capacity with rectifier and associated equipment. But the working of diesel generators in sub-zero areas of Himalayas is found not possible. Hence the PV solution would provide modules of 4.5 kwp to feed battery bank of 48 V x 1200 amperes would ensure 5 days autonomy. The set up would include a charge controller.

At El Negrito, a repeater station in Argentina, located at a height of 4200 metre above sea level, the temperatures can plunge rapidly to a —30C and the biting winds can reach speeds of upto 120 kmph. Even under such severe conditions, Solar PV arrays deliver upto 9400 watts of power reliably to meet the repeater`s permanent power requirement of 800 watt-hr. by charging a 48V battery-bank with a storage capacity of 4000 amp-hr.

In the Solar panels commercially marketed, generally 36 solar cells are housed in a module with voltage options of l2 or 6 volts output in the field.

The total power falling on a horizontal surface is called the global irradiance which reaches a maximum value of 1000 W/m2 at sea level and comprises two components, the radiations in the direct beam from the sun and the diffused radiations from sky.

An agency assigned with the task of planning the equipment for the high altitude (14000 to 2000 ft above MSL) will face a hard task, as none of the consultants in the field may have sufficient experience or hard data relating to the performance of the equipment in such locations. So intelligent judgement followed by the field trials are a must before undertaking the full scale work.

The choice may have to be made from the equipment marketed by some major firms in the field, such as the Siemens Solar, TATA-BP Solar and CEL. The efficiency of the cells hardly differ.

Since the backbone communications links (unmanned repeater /booster stations) are stationary and have much larger amp-hr consumption per day, they require large arrays. Hence larger modules would suit better.

For a VHF radio repeater station the requirement would be around 750 watt, for its base station 150 watts, but a radio trunking system would require around 5000 watt. HF Radio would need approx 150 watts. For hand-held radios foldable SPV modules of 10-15 watts would be most useful. For others, the larger modules or arrays can be considered.

An Indian company called Advanced Electronic Systems is currently engaged in the design and supply of SPV systems for powering remote microwave and V-SAT station at over 17 locations in Himachal using Siemens solar modules. Many of these sites are upto 40 km from the nearest road and are accessible only by trekking paths.

The maintenance-free rechargable batteries used with SPV modules or generally dry, sealed gelled type. The deepcycle lead-acid batteries with thick plates fall in this category. The Ni-Cd (Nickel-Cadium), Ni-MH (Nickel-Metal Hydride) and Li-Ion batteries, which though expensive are capable of withstanding wider extremes of temperatures compared to the conventional lead-acid batteries, also fall in the category of ‘gelled’type and have longer useful life.

Among the “gelled” type, we get AGM (Absorbed Glass Matt) batteries which are considered to be best suited to be used with the SPV system or for solar applications, as they require virtually no maintenance as they are provided with valve-regulation and are sealed. They have better resistance to gassing so can take faster “Charge” compared to the conventional flooded lead-acid type batteries.

Low temperature

In the case of the flooded category of batteries (lead-acid type) as the discharge continues, the hydro-sulphuric acid gets thinner of less concentrated and becomes more prone to freezing which occurs around -17C. On freezing the electrolyte expands, resulting in breaking up of the battery casing, creating messy conditions. At low temperatures of -30 to -50 C even the gelled type can freeze. Hence, precautions need be taken to safeguard against the freezing , and this may be in the form of enclosing the battery bank in an insulated enclosure and heating it using part of the energy being generated by the SPV system. The enclosure helps retain the heat during the night. Such arrangements are in use in snow-bound northern Canada in the unmanned repeater stations for microwave cellular trunking networks.

While deciding upon the capacity of the batterybank to be used with the solar system, the period of autonomy i.e. the duration of working without getting recharged need be fixed and the value for high altitude areas is around 4 to 5 days or 100 to 125 hours on account of rain/snow-storms.

Also factors like rapid reduction in the useable charge-capacity with fall in temperatures below-10 C need to be factored in.

For snow-bound areas, the solar PV cells with appropriate storage battery bank (type shown in figure 2) worked with a charge controller is the best alternative. Costwise, when compared to a diesel genset, it breaks-even in a period of approx 3-4 years whereas recurring fuel costs would have to be borne in case of the DG set. Performance-wise, SPV systems are virtually maintenance free with a reliable life of upto 25 years. They are also totally noiseless and pollution free and hence ideal for remote locations with fragile eco-systems.Top



 

Traffic jam has a solution
by Kalyan Ray

TRAFFIC snarl-ups may soon become a thing of the past with scientists designing a new computerised system to smoothen traffic condition.

Intelligent transportation systems (ITS) which may address problems inherent to current transportatation systems like road accidents and vehicular congestion are the trend of the day.

By using technologies such as lasers, optical techniques, image processing and global positioning system (GPS), ITS provides drivers a safe and uncongested route for their respective destinations.

The system can be split into five elements — advanced traffic management system (ATMS), advanced traveller information system (ATIS), automated highway system (AHS), intelligent vechile initiative (IVI) and advanced commercial vehicle system (ACVS) —a combination of which can make driving safer and quicker, reports IEEE Potentials.

However, the pinnacle of such systems is the AHS in which vehicles behave in two different ways — automated and non-automated.

In the automated part, each vehicle contains an autonomous computer which communicates with computers in other vehicles and with a centralised computer which is a part of the infrastructure.

Inside the AHS, vehicles are driven and controlled by this centralised computer-based system but once the car leaves the AHS the driver regains control of the vehicle to operate it manually.

Conceptualised in 1939, the AHS introduces the concept of a “platoon” vehicles communicate with each other to maintain appropriate distance and to follow the platoon leader.

In case of changing the lane, which is done cooperatively rather than competetively as is typical of humans, a vehicle communicates with its neighbours to split the platoon into two.

Once the platoon is split, the vehicles involved in the two new platoons coordinate with each other in a way so that only a single car is allowed to change the lane. After the vehicle changes lane, the split platoons re-merge. (PTI)Top


 

An exciting breakthrough
by T.M.S. Virdi

STORAGE Data Acceleration (SDX) is a new technology developed by Western Digital that significantly improves the performance of removable media storage peripherals such as CDROM drives. Instead of connecting directly to the PC via an EIDE (Enhanced Integrated Drive Electronics) interface, the peripherals connect directly to the hard drive through the new SDX interface (Illustration 1). The hard drive, which is a new generation EIDE drive that contains SDX technology, in turn connects to the host computer. The CD-ROM peripheral no longer needs the 40-pin EIDE interface since it now connects via a simple 10-pin cable directly to the hard drive. However through the SDX technology, the peripheral still appears to the host system as an EIDE or ATAPI CD-ROM drive.

SDX will be a strong addition to multimedia PCs. CD-ROM video clips will run smoothly, PC games can be played in real time, and software dependencies on particular CD-ROM drive transfer rates will be eliminated.

The improved CD-ROM performance via caching on the hard drive translates into an “x factor” up to 40x using an 8x CD-ROM mechanism. This performance improvement means that users don’t have to keep changing CD-ROM drives to get to the latest “x factor” thereby extending the useful life of the CD-ROM mechanism.

Win Bench 98 shows the following changes using an 8x CD-ROM drive with SDX compared to an 8X CD-ROM drive without SDX:

Most of the new hard drives (from Western Digital for instance) now support SDX. This means that any NEW hard drive can be used as a typical standalone hard drive or can have an SDX CD-ROM drive attached. As shown in Illustration 1, the CD-ROM drive no longer needs its own EIDE interface, but connects directly to the hard drive via a simple 10-pin cable. When the SDX CD-ROM is connected to the SDX hard drive, the hard drive automatically detects the presence of the SDX CD-ROM drive and configures itself with it. No jumper setting is required. This solution sets up fully compatible with existing PC hardware and software.

Western Digital is committed to putting the SDX specification in the public domain so the interface is open to everyone, just as IDE is today. Sanyo Semiconductor Division has developed an SDX-complaint chip set for CD-ROM drives and Sanyo Information Systems is the first company to offer SDX-compliant CD-ROM drives. A few other CD-ROM suppliers are also incorporating SDX solutions. SDX is fully applicable to other storage technologies and can support bidirectional data transfers, making it directly feasible with read/write technologies such as CD-R and CD-RW. SDX will be adapted to the emerging DVD standards including DVD-ROM (read-only) DVD-R (write-once) and DVDROM (rewritable). As hard drives move to higher performance via features like Ultra DMA, the attached SDX CD-ROM drives will automatically benefit from the performance improvement. When hard drives move to higher performance via serial interfaces, the attached SDX CD-ROM drives will also gain that performance benefit without needing any changes.

Short-term benefits to the user from this technology will be exceptional, but the real payback will be in the future, as more devices such as high-density floppies utilise this new SDX concept, allowing users freedom from worrying about which device to use, which connections, for which systems. SDX is an exciting technological breakthrough that moves the industry in a new direction.Top


quiz

 
  SCIENCE QUIZ by J.P. Garg

1. The British chemist and physicist John Dalton is well known for develoing atomic theory and the laws of chemical combination. It is amazing that he was also the first person to study a disease (of which he himself was a victim) often referred to as Daltonism. Can you name the disease?

2. SHARES is an international programme of cooperation between developing countries, including India, in a scientific field. What does SHARES stand for?

3. Biological mining? For extracting rare metals from mineral soil, suitable types of plants are grown in the soil and the metal removed from the dried and burnt shoots of the plant. What is this technique called?

4. PL-LCD will soon replace the screens of cathode ray tubes in television and computer monitors. It will impart same contrast, brightness and colour to the screen but at a much lower cost. What is the full expression for PL-LCD?

5. What is common about “muons”, “kaons” and “pions”?

6. What is the name of our galaxy? What is it popularly called in Hindi? What is its shape?

7. To ensure painfree surgery, a modern anaesthetic technique involves the insertion of a catheter (a thin plastic tube) into the back of the patient through which pain relieving drugs are injected continuously with the help of a special syringe pump. What is this technique called?

8. Working with computers for long periods may lead to blurred vision, headaches and itchy eyes. What is this new health hazard called?

9. Which phenomenon mainly explains the blue colour of sky? Who explained it for the first time?

10. Two neutral atoms A and B walking side by side bumped into each other. After separation, A said to B, “you naughty, you have taken away my one electron”. “How do you say that?”, asked B. What did A reply?

Answers

1. Colour blindness 2. SHARing of Experience in Space 3. Phytoextraction 4. Photoluminiscent liquid crystal display 5. These are elementary particles 6. Milky Way; Akash Ganga; spiral 7. Epidural Technique 8. Computer Vision Syndrome 9. Scattering of light; Irish physicist John Tyndall 10. ‘See, I am a positive ion.’Top


  H
 
  NEW PRODUCTS & DISCOVERIES

Separating metals

By using tiny inexpensive magnetic particles, US scientists have devised a new method of removing hazardous metals and radionuclides from industrial effluents.

The particles, usually made up of rare earth or ferromagnetic material, are coated with a extractant material that has an affinity for the targeted elements.

The coated particles are either poured into a tank that contains the contaminated solution or simultaneously added with the contaminated solution to an extraction vessel. To maintain particle suspension, the tank contents can be mixed by either mechanical stirring or magnetic fluidisation, or any other method.

The time necessary for the magnetic particles to “grab” the contaminants is usually within 30 minutes and then, the magnetic particle with their chemical-contaminant “baggage” are removed.

Monitoring of water quality

British scientists have developed a laser system to monitor water quality making the 100-years old means of measuring ‘five-day’ Biochemical Oxygen Demand (BOD) obsolete.

The method is set to change the standard BOD test that measures the oxygen demand of river and lakes receiving significant quantities of biodegradable organic material. The conventional test usually takes five days, making it unsuitable for instant on-line monitoring.

Moreover, it cannot differentiate between biodegradable and non-biodegradable matter.

The new laser system developed by researchers at University of Hertfordshire, can provide an extremely valuable additional contribution to improving the environment.

“When perfected, this method can help enable early detection of water pollution, according to Darren Reynolds, the system developer in the group.

The new technique uses ‘normalised’ fluorescence intensities to predict long and short-term variation in BOD from both industrial and domestic waste water samples, according to a report in Spectrum.

As light scattering can be easily initiated and detected by lasers, the technique can also be used to determine nitrate levels in potable water through differential absorption.

NASA’s Stardust to catch a comet

USA’s National Aeronautics and Space Administration (NASA) has launched the Stardust spacecraft on a mission to chase a comet and return a bit of its crown to Earth.

The space agency launched the Boeing Deeta-II rocket and sent the phone-booth sized, 385 kgs Stardust is on its way to a meeting with Comet Wild-2, five years hence and some 286 million kms from Earth, Reuters reports.

“The complexity of this mission is that not only do we have to get to where we are going, but we have to turn around and get home again”, said Ray Pilcher, NASA’s science director for solar exploration.

That sets Stardust apart from previous deep space missions. When the spacecraft’s return capsule makes a landing onto the earth on January 15, 2006, it will carry the first extraterrestrial matter ever collected from beyond the Moon’s orbit.

Comets are irregularly shaped masses of rock, icy gases and organic molecules, usually about a mile or so in diameter.

The materials inside them have been frozen for billions of years and can provide a unique glimpse into the origins of life on earth and, perhaps, elsewhere in the solar system, if such is the case, scientists said.

Comets may also contain elements from the stellar nebula that gave birth to the Sun and planets.

Comets regularly collided with earth until about four billion years ago, just before the earliest evidence of life.Top



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