• System requirements
• System design
• Hardware design

Why is the crust of Mars red?
Understanding the universe with Prof Yash Pal
THERE is enough evidence that Mars was quite wet some time. There is also an indication that iron exists on the surface. Liquid water is almost gone from the surface, and we do not have much oxygen there. Therefore it is easy to surmise that the red dust covering much of the Martian surface is nothing but iron rust! We know, of course, that rust is reddish in color.

New products & discoveries

• Hottest spot in solar system

• Self-cleaning clothes

• Human hair can remove oil

Towards safe rail crossings
by Prof Parteek Bhatia and Sanmeet Bhatia

RECENTLY there was an accident near Ludhiana where a school bus was rammed by a train, leading to an extremely ghastly death of small children. This is not an isolated happening on Indian railway networks. Every year, several accidents occur involving collisions of road vehicles with trains on unmanned railway crossings in rural and remote areas. The problems are particularly severe on crossings near curved/sloped tracks or hills, at nights and during rainy and misty seasons, as the oncoming train cannot even be sighted visually. Since the number of unmanned railway crossings in India is very large, the option of posting a round-the-clock gatekeeper to operate barricades is too expensive. To improve safety, we need to augment simple preventive measures like static warning boards near the gate and need to reduce dependence on human factors e.g., on train drivers for complying with mandatory actions like sounding horns on seeing a track-side signboard near the gate.

What is needed is a simple, cheap, robust, reliable and low power and low maintenance automated alarm system designed to help in reducing/preventing such accidents as far as possible. Ideally, to diminish bureaucratic resistance, such a system should not depend on any existing railway facilities like track power, signalling systems and track circuits (occupancy sensors). That is, it should be largely independent of the infrastructure of Indian Railways and should be usable on all tracks of any kind and gauge. It should be possible to adapt the system for a gate with more than one track. Also, installing and operating the system should not require too much intrusion on the existing tracks (e.g., digging, cabling etc) and trains and should not require much additional tasks to be done by the railway personnel. The power requirements should be as low as possible. Such a system should be reliable and fault-tolerant, fail-safe, easy to maintain and configure to many different situations.

By keeping all these system requirements in consideration Tata Research Development and Design Centre Pune designed the SAFECROSS system (Fig 1) that detects a moving train approaching an unmanned gate and then sounds an alarm and flashes a red light at the site of the crossing. Once the train departs, the alarm and the light are switched off.

The SAFECROSS system has three main modules, LOCO, GATE and REPEATER, each of which is equipped with an RF-transceiver. The LOCO module is mobile as it resides in the train’s locomotive; it continuously broadcasts a fixed RF (Radio Frequency) message.

GATE module is housed near the level crossing, which turns on a siren and red light when it starts receiving the RF-message from a train within its range and turns them off when the train goes out of the receiving range. Since the communication between LOCO and GATE modules should not depend on line-of-sight, zero or more REPEATER modules may be used as necessary on either side of the gate, REPEATER modules can also enhance the effective distance at which a train is detected, so as to give sufficient warning time to the road vehicles.

Since number of locomotives is much less than number of unmanned gates, this approach is more economical than using two train detection sensors at each gate. Use of RF avoids cabling, improves reliability and reduces maintenance problems. It also makes the SAFECROSS system completely independent of (a) gauge and number of tracks; (b) direction of arrival of the train towards the gate; and (c) railway track and signalling infrastructure.

The functional blocks are as follows:

Battery: This is a 12V, 10Ah battery to provide power to all the other blocks of the GATE module.

RF-Transceiver and Antenna: A low power RF transceiver is used to transmit and receive data packets on radio frequency 434 MHz; the range is 300m. For transmission, the current consumption is 50 mA and for receiver it is 16 mA.

LED1/LED2: These LEDs indicate the state of the GATE module.

Switch: For switching the GATE power on/off.

Low power Microcontroller: Controls/monitors h/w components, communicates with transceiver.

Solar power system: To charge the battery using a 12V, 10 Watts solar panel. Can be enhanced to provide back up power for GATE module.

Display and Alarm: A circular LED display (13 cm diameter, 500 mA) and optionally a buzzer to indicate the presence of a train near the gate.

It uses a smart power saving scheme using low power microcontroller and RF transceiver. Most of the time the microcontroller will be in sleep mode (wherein it consumes extremely small power) and the transceiver will be in receiver mode (wherein it consumes very little power). Upon receiving a message from a train, the microcontroller comes out of the sleep mode, performs its function and returns to the sleep mode. With this scheme, the battery is expected to last for two years, major requirements for hassle free operations in remote areas.

Once the train has an RF-receiver on board, a more flexible communication scheme can be incorporated into SAFECROSS so as to allow the user to inform the train driver of any untoward incidents. For example, on seeing any accident, dislocations or flooding on the track, a user can press a special button on the system so that the system can send a special message to the train driver, who can stop the train upon receiving the message. Alternatively, by computing the train speed and location, it can be sent to the GATE module, so that it can display the expected time of arrival to the road users. A smarter scheme to detect end-of-train (e.g., using a small range transmitter of a different frequency) can reduce the time for which the alarm is still on even after the train has passed the gate. It is very much clear that this type of technological development may be used for the benefit of mankind to save their lives from avoidable accidents.

Prof. Parteek Bhatia is from Deptt. Computer Science, DAV College, Amritsar, and Sanmeet Bhatia is Telecom Engineer, BSNL, Amritsar Division.

Why is the crust of Mars red?
Understanding the universe with Prof Yash Pal

THERE is enough evidence that Mars was quite wet some time. There is also an indication that iron exists on the surface. Liquid water is almost gone from the surface, and we do not have much oxygen there. Therefore it is easy to surmise that the red dust covering much of the Martian surface is nothing but iron rust! We know, of course, that rust is reddish in color.

It is amusing that because of this rusty exterior, astrologers tend to give a special character to Mars - it is supposed to be a virile and angry planet. This interpretation affects the lives of many who still believe in astrology.

We do not have definite evidence for existence of life on any of the planets except the earth. Titan has been considered an interesting candidate because there is evidence of abundant subterranean water and we tend to believe that wherever we have water there is a chance that life might have had a chance to grow. It is impossible to say anything more positive about existence of life on Titan.

Some watches are said to have radium dials to enable reading of time even in dark. Are the markings on these dials made with something that contains radium? If so aren’t they injurious to health?

You are right. Till the middle of the last century such watch dials were made and were quite popular. Little bit of radium was mixed with a material like zinc sulphide to prepare a paint to cover the writing on the dial. Radioactive emissions of radium produced light from zinc sulfide. The girls employed to paint the dials often sharpened their brushes by putting them under their lips. It is said many of them became sick, with their teeth falling out or suffering from oral cancer. Radium is even more dangerous when imbibed because of its long life. Such watches have now gone out of circulation, even though there is not much danger in wearing a properly encased watch. These days watches with luminescent dials are available that use a phosphor that remains visible for several hours after being exposed to light.

I do not know what gum you are referring to. Ordinary gum is a bit watery. Or it might have another solvent. When you take it out of the bottle or apply it on a piece of paper it is sure to dry out and become solid. Some adhesives set after they are brought in contact with moisture in air. Other adhesives are prepared for application after mixing two components. They need time for "curing". This time is often dependent on temperature.

I think the easy answer to your question is that sodium light is as close to being yellow as possible. The point is also connected with the way we define yellow? What range of wavelengths would satisfy us? And how well we judge the blueness of blue, and blackness of black? Blue, yellow and red being the primary colours whose combinations can define all other shades of colour for us, no yellow is reflected by a blue object and hence it appears black.

Hottest spot in solar system

The hottest spot in the solar system is neither Mercury, Venus, nor St. Louis in the summer. Io, one of the four satellites that the Italian astronomer Galileo discovered orbiting Jupiter almost 400 years ago, takes that prize. The Voyager spacecraft discovered volcanic activity on Io over 20 years ago and subsequent observations show that Io is the most volcanically active body in the solar system. The Galileo spacecraft, named in honour of the astronomer Galileo, found volcanic hot spots with temperatures as high as 2,910 Fahrenheit (1,610 Celsius).

Self-cleaning clothes in future may make washing a thing of the past.

Researchers have invented an efficient way to coat cotton cloth with tiny particles of titanium dioxide. These nanoparticles are catalysts that help to break down carbon-based molecules, and require only sunlight to trigger the reaction.

The inventors, Nature magazine says, believe that these fabrics could be made into self-cleaning clothes that tackle dirt, environmental pollutants and harmful microorganisms. They may wear out but would never become dirty so long as sunlight is available.

The titanium dioxide particles covering the cloth are just 20 nanometres across, about 2,500 times smaller than the width of a human hair.

The researchers’ key breakthrough was to ensure that these particles had exactly the right arrangement of atoms, called an "anatase" crystal structure, which has previously been difficult to achieve in such tiny grains. This arrangement boosts the particles’ catalytic power, Nature says.

Waste human hair has found a new use that can potentially make barbers rich.

A team of chemical engineers at Dharmsinh Desai Institute of Technology in Nadiad has found that human hair is an excellent medium for separating oil from water.

Industries currently spend a lot of money on chemical methods for separating oil from factory effluents to meet pollution standards.

"Since human hair is very cheap the method may find a good usage for it (oil water separation)," scientists Z V P Murthy, Gautam Kaushik and Ritesh Suratwala reported in the Indian Journal of Chemical Technology.

"The efficiency is nearly 100 per cent for free oil," their report said. "The most intriguing thing is its efficiency in separating emulsified oil."