Category Archives: Engineering

Shake or Stand?

Taipei 101
Taipei 101

Recently in my physics class, the teacher talks about waves and I suddenly remember a show that I watch on National Geography before about Taipei 101, now one of the world’s tallest buildings. Taiwan is a place where earthquakes happen frequently, thus it is very important to make buildings quakeproof, especially for Taipei 101 because of its extraordinary height. To understand how building is designed to be shockproof, we need to first understand how building collapses under the effect of waves, either winds or earthquakes.

So, how does building fail when it is under the effect of waves? Using an earthquake as an example, during an earthquake, the ground is shaking, and the lower part of a building shakes in the same direction as the ground. However, it takes some time for the waves to transfer to the upper part of the building, so the displacements of the lower part and upper part are different. The number of times that a building swings back and forth is called frequency. And all building has a natural frequency, which is a frequency that the energy of the quakes can be transferred most efficiently. When the frequency of quakes get closer to building’s natural frequency, the greater the building will swing, and more damage will be done to the building. (Thomas, “Quake-proof”)

Taipei 101 locates at a place where earthquakes happen frequently, and with its amazing height, wind vibration is also a problem. And how do the builders of Taipei 101 solve the issues of continuous vibrations of the building? They build a huge and heavy tuned mass damper (TMD) within the building. For building as big as Taipei 101, the TMD must be huge. In fact, the TMD in Taipei 101 is 5.5 meter in diameter and weights more than 600 ton. The damper is a pendulum hung from 92nd floor to 88th floor that is “tuned” to match the natural frequency of the building. It will vibrate in the opposite direction to the building, so the forces cancel each other out. Those people who are in IB Physics class might remember the video that Mr. Happer shows us in class on how two waves in opposite direction cancel each other out when they meet. (“Taiwan On Top”)

Tuned Mass Damper in Taipei 101
Tuned Mass Damper in Taipei 101

Why do people build architectures? The purpose is to protect us from the natural forces in the environment around us. The forces can be as small as a rain or as big as an earthquake, and buildings are supposed to shield us from those forces. Our ancestors develop different kinds of building styles in response to differnt dominated forces in a region; throughout time, the building styles become part of our culture. People live in different terrains build architectures differently because they have different problems to solve. However, the difference in building styles demonstrates a common attitude amongst all cultures. This attitude can be best described by a Daoism principle, to act like water. Water is soft and easily changable, and it can change to adapt its environment. The design of Taipei 101 reflects this attitude, since it doesn’t try to fight against nature, but rather the building “shakes” with it.

BiBliography

Thomas, Rachel. “Quake-proof.” +Plus Magzine.com. +Plus Magazine, 10 Feb. 2005. Web. 21 Feb. 2011.

“Taiwan On Top.” ArchitectureWeek.com. ArchitectureWeek, 02 Mar. 2005. Web. 21 Feb. 2011.

“Structure.” Taipei 101.com.tw. Taipei 101, n.d. Web. 21 Feb. 2011.

“Giant Damper Doubles as Building’s Interior Adornment.” ENR.com. 24 Nov. 2003. Web. 21 Feb. 2011.

The Doctor and his blue box

When I was reading Alex’s post about start wars and if a Lightsabers could be made I started to think about my favorite sci-fi shows and if the facts could be true. I am a huge fan of the British tv show Doctor Who, but could a Tardis or sonic screwdriver actually be created.

dr_who

For those of you who don’t know the show, its about a time lord from the planet Galifery, he has two hearts, and can reincarnate 12 times and yes you guessed it he can travel in time. His time machine is the Tardis a blue police box. He always travels with a human companion and together they travel in time and space and save the Earth and the Universe. The show originally aired on November 23, 1963 and is still running today with the 11th Doctor played by Matt Smith. The doctor has fought all types of alien creatures from the Daleks to the Cybermen. Could these ideas be true that arise from the tv show that millions watch.

The Doctor’s Tardis or Time And Relative Dimension In Space, is how he travels throughout time and space to continually save the universe. But could the idea of time travel be real. Professor Kip Thorne and his team from the California Institute of Technology have proposed that an advanced civilization might be able to build a time machine. This idea used the idea of a wormhole (a short tunnel through time and space based on Einstein theory of relativity). Thorne’s theory consisted of two mouths of a wormhole by putting one on a spacecraft and flying it at the speed of light. This connects to Einstein’s theory of relativity that time passes slower for a moving object compared to a stationary one. So therefore the spacecraft travels at 0.9 at the speed of light on Earth two years would have passed. So when you jump out of the wormhole you would arrive a year in the past.

The Tardis

How about the Doctor’s famous sonic screwdriver? His screwdriver projects a concentrated beam of sound that can weld metal and open locks. Professor Douglas Adams, a noise and vibration engineer at Purdue University, Indiana believes that the sonic screwdriver could work, if the sonic screwdriver was short-range. It would work based on the principal of structure-acoustic linear ultrasonics. He says. “You produce a focused column of oscillating air particles (sound waves) that is directed towards an object, say a screw. These oscillating air particles set up high-frequency oscillations in the screw, causing it to rattle along in the direction of the threads to either tighten or loosen.” This technology is being considered to replace the mechanical motor bearings used in computer hard drives. Although according to Professor Adams the Doctor’s exact sonic screwdriver could never be made, “To get a non-contact acoustic device to fit in the doctor’s pocket, we would need to develop a new kind of power source.” Professor Bruce Drinkwater of the University of Bristol states that the ultrasonic sound waves can actually apply forces to objects, “Doctor Who is renowned for bending the rules of science. But technology has radically moved on since the Doc first stepped out of his Tardis in the sixties. Whilst a fully functioning time machine may still be light years away, engineers are already experimenting with ultrasonic waves to move and manipulate small objects.” Engineers are experimenting with rotating ultrasonic force fields could operate as the head of the screwdriver.

The implication of these creations being real would be that civilization from the future might be able to travel in time and that would change the course of history and the world. If we were able to be created even a sonic screwdriver it shows that anything we set our minds to if we work hard enough and there is the resources that you need you can create what you want. “Doctor Who’s adventures have captured the imaginations of millions, young and old. And, however far fetched the Time Lord’s encounters may seem, there are engineers and scientists out there who are using their skills to bring the magic to life.” Professor Bruce Drinkwater.

References:

“BBC – Doctor Who – The Official Site.” BBC – Homepage. Web. <http://www.bbc.co.uk/doctorwho/dw>.

Gribbin, John. “Time Travel for Beginners.” Everything You Always Wanted to Know about Time Travel. Web. <http://www.lifesci.sussex.ac.uk/XXhome/John_Gribbin/timetrav.htm>.

Parsons, Paul. “Who Believes in Who – Telegraph.” Telegraph.co.uk – Telegraph Online, Daily Telegraph and Sunday Telegraph – Telegraph. 28 Mar. 2008. Web. <http://www.telegraph.co.uk/technology/3345437/Who-believes-in-who.html>.

Swat, Texas. “Sonic Screwdrivers Using Ultrasonic Force Fields: Science Fiction in the News.” Inventions and Ideas from Science Fiction Books and Movies at Technovelgy.com. Web. <http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=3119>.

Lightsabers, fact or fiction?

If you periodically check Yahoo! like I do you will have noticed recently that there was an article about the resurgence of popularity concerning the Star Wars series as the full series is about to be released on Blu-ray. Well you would have had to have read the article to gain that particle information, but perhaps you saw the small thumbnail of a picture of Darth Vader donning the red light saber and Luke the green one.  It got me thinking could such a sword actually exist or one day be created?

I started researching. I figured that Star Wars with its cult following already had people try or are currently trying to create a real life lightsaber.

The lightsaber, the the primary weapon of the Jedi knights in George Lucas’ Star Wars. Wether a Star Wars devotist or not it cannot be denied that this weapon is pretty awesome by itself. The idea of a sword that can cut through anything, melt anything and deflect shots is sounds king of amazing. Not to mention the awesome colors and glowing effects, compounded with their famed sound effects, who wouldn’t want one?

What George Lucas created with flashlights and animation genius takes a bit more science and thought (although I’m sure its animation was very hard to produce).  The basic principle of the lightsaber is that it is a (light) beam of controlled energy that stops at a certain length and “opens” and detracts with the flick of a switch and is self sustaining (ie. not needing batteries, or recharging).  It’s blade of energy is supposed to be focused from a crystal inside the hilt of the sword.

(Ideally) The cross-section of a lightsaber

However, Dr. Michio Kaku, a theoretical physicist did introduce to viewers of the show Sci-Fi Science: Physics of the Impossible that at the university where he works, City University of New York, they are able to harvest their own crystals. These crystals however, fully able to produce laser beams would not exactly fit the lightsabers description as the beam would be a thin ray of light and not solid. Having a lightsaber that can’t deflect another lightsaber would make it very difficult to Jedi to Sith. Furthermore, the laser beam would become invisible in the daylight or in a room with lights on. Now with this new safety hazard added, having a laser beam from a crystal does not seem plausible for the real construction of a light saber.

However, there have been suggestions to try using plasma. Plasma, the fourth state of matter, is similar to gas except a portion of its particles are ionized. Dr. Kaku in another episode creates a possible design for a lightsaber using very hot plasma. His design allows for a fan at the base of the hilt, that when you turn it on, it sucks up air into the saber and nano tube batteries to super heat it creating very hot plasma. To keep the plasma from oozing out, an electromagnetic coil will be wrapped around the “blade” of the sword. This blade will be made of ceramics so as to withstand the high temperature. Sounds like it could be created, right?

This knowledge opens the gateway for a lightsaber to be constructed, maybe a new age of warfare will erupt with a more “elegant”.  On a more realistic level this design is just an example what else the human race is capable of designing and then constructing. However out-of-this-world the idea is, someone, somewhere, probably a a theoretical scientist, will figure out a way to make it a reality. This can only serve to inspire scientists and future scientists in their work as well as giving them no limit to their imagination and what they might be able to do.

Dr. Kaku’s design was the most plausible that I could find and one of the few that took the design seriously to be realistically created here on earth. The fact that he could come up with a design gave me hope for all of the seemingly supernatural elements or props shown in movies, giving all of the Sci-Fi movies I watch a certain element of reality.

The technology is in our grasp and maybe one day…

we will look like this.

Sources

“Are Lightsabers possible?” physics.org. Web. 9 Jan. 2011.

“How Lightsaber Work.” Howstuffworks.com. HowStuffWorks, Inc. Web. 9 Jan. 2011.

“Lightsaber.” Chemistry Daily. 4 Jan. 2007. Web. 9 Jan. 2011.

“Science Channel Video.” Science Channel. Discovery Communications, LLC. Web. 9 Jan. 2011.

Shocked by a Dam

After being let off from work or school, people go home and turn on numerous appliances in their everyday life that require electricity. The population of Shanghai is about 19.3 million (True Knowledge) people as of November 2010. At night, when all of these people return from work and turn on their lights, there is a huge increase in the demand of electricity. The electricity company, Shanghai Power, has to meet those demands. But how on earth are the electricity suppliers able to meet the demands of 19.3 million people? This was the first question that came into my mind whilst we were building circuits in my physics class. This is because in my physics class the circuits we built are powered by batteries, which was our source of electricity; so that made me think on a larger scale, where does all the electricity that is required to power our appliances come from? Having done some research, I realized that such an enormous demand for electricity is met with a single dam. A dam that will create a 400 mile long reservoir, produce electricity 8 times (18.2 million kWh, Kennedy, CNN) that of US’s Hoover Dam, costing $35 billion USD, taking 17 years to build (Neville, Discover Yangtze), and is China’s largest civil engineering project since the Great Wall. Ladies and gentlemen, the Three Gorges Dam.

Picture of the World's largest dam, Three Gorges.
(Figure 1: Picture of the World's largest dam, Three Gorges.)

The Three Gorges Dam is constructed on China’s Yangzi (Yangtze) River, the third longest river in the world. This idea of constructing the Three Gorges Dam was conceived by Mao Tse Dong in the 1950’s after numerous floods along the Yangzi River, but construction of the dam only began in the 1990’s. The construction of the dam was not only meant to meet the increasing demands of electricity but also to control the notorious flood-prone Yangzi. So how does that work? Well, by damming the Yangzi, it already effectively slows down the river’s powerful, and strong currents downstream where there are farmlands and villages. The water from the upper and higher part of the dam will flow down the spillway to the lower portion of the river should the water level of the dam be too high. So how does a hydroelectric dam work? Water flows through the penstock, or a tunnel that carries water to the turbines (Figure 2). The turbines of the dam are turned by the powerful force of the water flowing from the penstock onto the blades. The turbines, attached to a generator, turns the generator, thus producing the electricity carried by power lines to cities.

(Figure 2) Picture of how a Hydroelectric dam works.
(Figure 2: Picture of how a Hydroelectric dam works.)

The only output from hydroelectric dams is just electricity and water, unlike coal plants where the burning of coal produces carbon dioxide one of the main contributors to global warming. This is why building a hydroelectric power plant is much greener, or more environmentally friendly than a coal plant. Or is it? A scientific concern arising from the Three Gorges project is whether the dam will reap more than it destroys, meaning will the dam be more beneficial than harmful. Looking at this project from an engineer’s point of view, the Three Gorges is undoubtedly China’s greatest project undertaken since the Great Wall. My personal bias is that I want to become an engineer when I grow up. This is considered a personal bias because I will be looking at the Three Gorges Project from an engineer’s point of view rather than an environmentalist’s perspective. Which would put me more in favor of the construction of the dam than against it.

Nonetheless, different perspectives must be taken into consideration. So, putting on your environmentalist glasses and looking at this project from their perspective, the Three Gorges Dam would seem to be a catastrophe on nature. This is because the dam will inundate approximately ‘632 square kilometers’ of land, which is a little short of the size of Singapore, or 17 times the area of Manhattan. Such a huge area being submerged (Figure 3) creates a lot of concern because of the lack of attempts to remove toxic materials and other pollutants from industrial sites that are being inundated. The toxic materials could potentially pollute the reservoir causing harm to the 177 species of fish that live in the Yangzi. But the concerns don’t stop there. There is also a huge problem about the plants that will be affected as a result of the Three Gorges Dam.

(Figure 3) Satellite picture of before and after image of the Yangzi River.
(Figure 3: Satellite picture of before and after image of the Yangzi River.)

The area that will be inundated accounts for 6000 plant species, which is 20 percent of China’s plant species (Hvistendahl, Scientific American). Therefore, it is important that we know all of this because in the future, should there be any more projects as monumental as the Three Gorges, we will know that many factors and effects of the dam must be kept in mind and taken into consideration. Although there has been a lot of research about the effects of damming up a river, much is still unknown as damming a river on such a monumental scale is still at its primitive stages. Meaning, there isn’t much knowledge about the effects of damming the third longest river in the world on such a humongous scale. So, was building the Three Gorges dam a correct decision? As an old quote goes: “The only way to know whether you’ve chosen the right path to follow is after you’ve reached the end of it.” Which means that only time can tell us whether the decision to build the Three Gorges Dam was a correct or erroneous one.

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Video Link: Three Gorges Dam

For further inquiries: Three Gorges Project

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Works Cited

What is the population of Shanghai 2010?” trueknowledge.com. True Knowledge, n.d. Web. 19 Nov. 2010.

Kennedy, Bruce. “Visions of China- Asian Superpower: China’s Three Gorges Dam.CNN.com. CNN, n.d. Web. 20 Nov. 2010.

Hvistendahl, Mara. “China’s Three Gorges Dam: An Environmental Catastrophe?scientificamerican.com. Scientific American, 25 Mar. 2008. Web. 20 Nov. 2010.

Neville, Peter. “THE THREE GORGES DAM.discoveryangtze.com. Discover Yangtze, n.d. Web. 19 Nov. 2010.