Category: Engineering

Gravity Light – A Light With No Running Costs

By Anupum Pant

Visit blogadda.com to discover Indian blogs
A $5 lamp that lights up using gravity can be used without electricity or batteries, over and over again with no running costs. Impressive enough? There is more.

A British company, after working for 4 years on this project, with an aim to replace kerosene lamps, started an internet fundraising campaign on Indiegogo and successfully raised about 7 times more than what they had aimed for – aimed for raising a fund of $55,000 and ended up raising $399,590. They had invented the Gravity Light.

Gravity light uses the force of gravity to light up – a free, completely reliable and totally unlimited source of energy. For it to start, the user is supposed to lift up a hanging weight of about 10 kg. And there! As the bag full of dirt, stones or sand starts coming down slowly, it lights up an LED light. The weight keeps coming down for about 30 minutes and then it has to be raised again. It generated a very minuscule amount of electricity and manages to give out a much brighter light than a kerosene lamp.

The energy generated from it can also be used to charge batteries, charge phones, run a radios etc, with attached accessories.

Interestingly, the company has plans to develop various other gravity powered solutions. So, in the future, we might probably see a way to reach the internet without batteries or electricity.

Other interesting lighting ideas:

[Gravia lamp] [Water + Bleach lamp] [Algae + CO2 lamp]

 

Yakhchal – An Ancient Cold Storage Marvel

By Anupum Pant

Visit blogadda.com to discover Indian blogs
During a period when electricity was only a thing for the Gods, around 400 B.C.E., in the hot-arid deserts of Iran where temperatures touched 40 degree centigrade, ancient engineers had found a way to keep their ice from melting. Two thousand years back, a cold storage facility was being used. The impressive thing about it – it was clean and sustainable technology.

What are these?

Yakhchals, or ice pits of ancient Persia were the huge mounds (buildings hollow from the inside), which made it possible for Persians to store away the ice for summers, meat, dairy products, other food items and chilled frozen Faloodeh for the palace. Beside treats for the palace, the method of preserving ice was so professional yet simple that even the poor could afford it.

Structure and Working

The structure of these buildings above the ground is a large mud brick dome, often rising to about 60 feet in height. Below it are large underground empty spaces, up to 5000 cubic meter in volume. This space had access to wind catch and often contained a system of wind-catchers that could easily bring temperatures inside the space down to frigid levels in summer days. The structures were built so well that many still remain standing.

Working: The massive insulation built into the walls (due to the use of a special mixture of sand, clay, egg whites, lime, goat hair, and ash) and the continuous cooling waters that spiralled down its side kept the ice frozen throughout the summer by evaporative cooling (just like those mist fans). They also had a trench at the bottom to catch water from the molten ice and to refreeze it during the cold desert nights. The ice was then broken up and moved to rooms deep in the ground. As more water ran into the trench the process was repeated.

Geography: These were built in the areas that had suitable condition for producing natural ice or places where there was feasibility of water freezing during the cold nights.

Major architectural elements: 

  • Shading wall – To avoid direct exposure to sunlight and to let the structure remain cool in the shade.
  • Provisional pool – To supply water for evaporative cooling to take place.
  • and Ice reservoir – To keep the cycle going. Freeze > Melt > Refreeze at night and so on…

The end of Yakhchal (reasons)

  • Since the advent of electricity-guzzling freezers and air conditioners, unfortunately, the use of these architectural wonders has been considered as foolishness. This is probably the reason no Yakhchals are being used for cold storage anymore.
  • Desert storms, caused a lot of erosion to these structures, especially to the ones that were isolated in the desert regions.
  • Since Yakhchal’s ice formed in the open it was prone to combining with dust and resulted in contamination. That was another reason it wasn’t considered as a choice useful enough for modern purposes.

Hit the like button if you learnt something from this article.

4D Printing is Here

By Anupum Pant

Visit blogadda.com to discover Indian blogs
We had just started getting comfortable with printing objects in 3D, and 4D printing is already here. Early this year, in the month of April, Skylar Tibbits, an architect, designer and computer scientist at MIT, gave a revolutionary demonstration explaining their advances in the field of 4D printing at a TED conference. This was an initial proposal and it got things moving at a rapid pace.

Side note: In the world of 3D printing:

What is 4D printing?

At first 4D printing sounds like a catch phrase, it isn’t really just that. 4D printing is actually 1D better than 3D printing and it aims at making objects out of a 3D printer, that can reconfigure themselves into useful shapes, on their own. For instance, think of a non-living stick changing itself into a 3D cube as time passes. In short, 4D printing will enable us to create living objects without any living cells, micro-processors, chips or batteries involved. Sounds simple enough, but the promises are nothing less than extraordinary.

In the TED talk attached below, Skylar explains how a string of plastic placed in water can turn itself into the letters MIT. But, this was something that happened back in April. Things have moved further.

A few days back, Researchers at the University of Colorado Boulder revealed a successful test of their 4D printing technology. They were able to print out flat objects using normal plastic combined with a smart material which was able to turn into a cube on its own. Cubes are just the start.

According to scientists, in the future, 4D printing will probably churn out smart car bodies that would heal automatically, smart soldier uniforms and advanced building materials. Imagine a camouflage material that changes to match the surroundings, that could be the future. Or a pipe that contracts and expands to move water without pumps. Or a building material that builds itself into a structure. 4D printing could probably best suited for building in an extremely hostile environment like space. The possibilities are endless.

But, let us not get ahead of ourselves. It is almost impossible to predict what we’ll actually see in the future. Things have just started to happen in the field of 4D printing. But, it sure looks amazing. What will you build?

Super-hydrophobic Surfaces are Unbelievable

by Anupum Pant

It is almost impossible to get a lotus leaf wet. If you try pouring water on it, you’ll see that it will form little beads of water and quickly roll out of the leaf. This happens because a lotus leaf is super-hydrophobic. Although, even your raincoat doesn’t get wet, it isn’t super-hydrophobic. Water sticks to on the surface of a raincoat. Super-hydrophobic surfaces don’t let water stick on it. But how do they manage to do that?

The science – Contact angle

Every time a liquid sits on the surface of a solid, the liquid drop forms an angle of contact as shown below. Things that don’t get wet have a contact angle greater than 90 degrees and the ones that get wet form an angle lesser than 90 degrees. The greatest angle is always less than 180 degrees. Theoretically, a perfect bead will form at that angle.

Super-hydrophobic surfaces are able to push this angle to as high as 175 degrees to form almost a perfectly spherical water droplet on the surface (due to very high surface energy). This ensures that as soon as water falls on it, it rolls away. The surface never gets wet.

Advantages

Imagine things never getting wet. How about a completely water resistant phone, a shoe that never gets dirty, shirts that repel ice-cream and wind-screens rolling away rain droplets like magic? All these things are possible, if they can be converted into super-hydrophobic surfaces. [They can be. Watch the video below]

Besides repelling water, these surfaces can also prevent formation of ice, resist corrosion and prevent bacteria from sticking to it. The possibilities are endless.

How to do it artificially?

Today, we have managed to develop several artificial methods to make almost any surface super-hydrophobic. Commercial services like NeverWet, HydroBead and Lotus leaf coatings are making a roar in the market by offering amazing promises. Normally, they use simplified spray coatings to convert normal surfaces to super-hydrophobic surfaces, so any one can use them, anywhere.

Plasma Speakers

by Anupum Pant

Not many would have heard of speakers other than those which use magnetic materials to produce sound. But if you still haven’t heard about Plasma speakers or ionic plasma tweeters, you are really missing something great. Read on for more.

About Plasma Speakers

I talked about sound a few days back and mentioned that it is something that propagates through a medium due to pressure changes. Normally, magnetic speakers create these pressure waves by moving a diaphragm with the help of a varying magnetic field. But, plasma speakers do this by varying the air pressure through a high energy electric arc. This arc is produced by ionizing the gas present in between two terminals (ionizing reduces the electrical resistance of air which creates a visible arc).

These speakers use an extremely high energy arc which also increases the temperature of surrounding volume of gas to very high levels. So, before learning anything about them, the first thing you have to know is that these seemingly harmless things can kill you.

The Dangers

Plasma speakers are not toys. Old men, people with heart problems, kids etc should stay away from them. Even if an adult is handling them, they need to be informed about what they are doing first. It is better to have someone close who knows well, how these things work. Although the commercially available speakers are fairly safe, DIY kits can prove to be fatal. The kind of dangers involved with these devices:

1. The electric discharge – Think of it as a lightning. The dangerous high voltage device has the potential to kill you, if any of your body part comes close. Keep all bodily parts away.

2. Gas danger – The constant supply of ozone used for this project can actually be much more dangerous than the electric arc. Ozone used in this project, silently increases in concentration which can be fatal. It is important to keep the room well ventilated.

A few more things about them

Invented by WIlliam Duddells in the year 1900 these are not speakers, but tweeters. That means, that there will be no window cracking bass that is going to come out of them. Unlike magnetic diaphragms, the arcs have no weight and are able to produce a very crystal clear sound by moving back and forth very quickly. See the video below.

They work by changing temperature inside the gas chamber which makes them go red to purple as the frequencies of a song change. However, an un-modulated arc will just produce noise, something like you hear at first in the video. Also, they need a constant supply of Helium and Ozone coming into the chamber. These gases get ionized inside to produce the arc.

[Read this for more history]

Where can I get them?

In 1970 Magnat used to produce them, but they no longer produce plasma speakers now. The point is, they were the pioneers in bringing this to the masses.
Acapella sells them for an eye-popping price of 23000$. These costly ones are revered for their sound quality.
Other DIY kit can be bought for as low as 100$ [here]
Build one on your own for cheaper. (if you are willing to risk your life) [tutorial here]

 

Bricks Which Are Lighter Than Air

by Anupum Pant

What would smoke look and feel like, if you could solidify it?

Aerogels

Although, first made in 1931, Aerogels are relatively newer materials and a tremendous amount of research is being done on them everyday. Lightest solids ever, Aerogels weighing about seven times lesser than air have been made. Their extreme properties have given a fascinating field of interest to students and scientists. [Read the last paragraph]

How are they made?
Aerogels, also known as solid smoke or frozen smoke are extremely light materials. They are made by a process called sol-gel process which involves removing all the moisture from a specially made gel (Hypercritical Drying). Although the procedure may sound simple, there is a lot of technology involved in making them. Moreover, practically usable Aerogels which can endure moist conditions and high stress conditions are much more challenging to make. Also, it is very expensive to make them. [They can be made at home – with costly equipment of course]

Why is it so light? 
The whole lot of porosity left inside due to drying of the gel is what makes it so light. You can think of them as a sponge which is hard like pumice. But, when you think of a sponge, remember that mostly Aerogels aren’t very resilient. That means, unlike sponge they won’t get back into the previous shape after they’ve been pressed a lot. They are much sturdier/tighter than sponges. A small (not very small; due to very low density they occupy large space) piece of Aerogel weighing just 2 grams has been shown to hold a 2.5 kg brick without deforming. Poorly made Aerogels, on the other hand can also not be very sturdy. They would deform with a hard press of a finger and stay deformed.

How light are they?
Agreed, they can be lighter than air, but the practical mass varies greatly. And they don’t float in air because, with air present inside them, they are slightly heavier than air (weight of air inside + solid material), but can be made to float in air by replacing the air inside it with Hydrogen or Helium. Their lightness and density is completely dependent on the amount of porosity included during the fabrication – which can be controlled. Also, the kind of gel used to make it, affects the weight of the final block. So a block with 3 feet in length, breath and height can weigh anything from 1 kg to just 160 gm.

Aerographite, a carbon Aerogel made by German material scientists from Kiel University and the Hamburg University of Technology, was said to have weighed only 0.2 mg per cubic centimeter. It was 5000 times less dense than water and 6 times lighter than air (counting only the solid material’s weight of course). [Published Paper]

Graphene Aerogel: As if that wasn’t enough, recently, Chinese material scientists developed a lighter material than Aerographite. It was based on Graphene. A Graphene Aerogel; seven times lighter than air. This one, unlike other silica Aerogels, can recover like a sponge after getting deformed. [Published Paper]

Other Properties

Aerogels exhibit various other desirable properties which make them useful for a myriad of applications [See the Wikipedia Article]. For instance, they are very good insulators of heat. A nicely made Aerogel block which is just under a centimeter thick can protect things from a direct flame. Other desirable properties are high surface area, high thermal and acoustic resistivity, low dielectric constant, and low refractive index.

Aerogels absorb water or moisture from the air and even from human skin easily. Handling them with bare hands can cause blisters. But, the ones which repel water have been made successfully by altering fabrication parameters. Also, if particles of it are inhaled, it can cause problems. Hence, hand gloves and respiratory masks are used to handle them.

I want to study interesting materials like these

If you think Aerogels and Wolverine’s claws are interesting things. You can make a career in researching materials like these by making a foray into Materials Science and Engineering. Most good universities offer a course in it. It is a budding field, growing at a rapid pace with loads of opportunities waiting for you.