Thursday, November 29, 2012

MAGNETISM


Magnetism in Technology
Magnetism is a huge part of some very advanced technologies that make a big difference in our world. Let's take a look at a few important technologies where magnetism plays a big role.
Hard Drives
Hard drives are an important part of any computer system, and magnetism is the key behind how they work. Hard drives uses disks made of magnetic material, called platters, to store information.
Hard Drive Platter Read Write Head
A Hard Drive Platter ©Wikipedia CommonsRead/Write Head © Wikipedia Commons
An electromagnet in the read/write head writes writes information to the disk by magnetizing small sections of the disk, called sectors, in a one direction or another to indicate a 1 or a 0. The same read/write head also detects the orientation of these sectors when reading information from the disk. Previously, the sectors on the platters were magnetized parallel to the surface of the platter. This style of recording was called longitudinal recording.Longitudinal Recording
However, a breakthrough was made by magnetizing the platters perpendicular to the platter, allowing for more information to be stored in the same amount of physical space.This new style, called perpendicular recording, has allowed for hard drive capacities to increase greatly.
Perpendicular Recording
Perpendicular Recording
Check out this video from Hitachi Global StorageTechnologies to learn more about new method of recording.

Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging is an example of magnetism being applied in the medical field. This technology is a type of medical imaging that uses magnetism and the large percentage of water in the human body to produce detailed images of human body tissue and structures. MRI images are high in contrast, and allow doctors to examine different types of tissues in a region of the body more easily and accurately.
MRI Image An MRI image of a human head. © Daniel Schwen
MRI machines place the patient in the center a long cylinder surrounded by large, powerful permanent magents, electromagnets, and sometimes superconducting magnets, along with many coils of wire.
MRI machine An MRI machine. © Wikipedia Commons
Once the body is inside the machine, the water molecules (specifically the hydrogen atoms) inside the body are magnetized in the same direction by a large magnetic field. Then, a radio frequency pulse is directed towards the specific region of the body being examined. Different types of body tissue respond to different frequencies. The radio frequency energizes the hydrogen atoms of a specific tissue and causes them to flip out of alignment from the rest of the hydrogen atoms in the body. When the radio frequency is removed, the disturbed hydrogen atoms slowly return to the magnetized state. As they return to the magnetic field of the machine, they release the energy they recieved from the radio frequency. The coils of wire in the machine detect the energy released, and an image is formed the detected bursts of energy.
MRI Hydrogen AtomsMRI Radio Pulse



Magnetic Levitation (MagLev) Trains

Shanghai Transrapid Maglev Train in Japan
Shanghai Transrapid ©Wikipedia Commons  JR-MLX01 Maglev Train ©Wikipedia Commons
Magnetic levitation trains, more commonly called MagLev trains, are a technology that could bring big changes to the way we travel in the future. These trains use magnetism to "float" without friction on top of a special track, creating a faster and more efficient method of transportation. These trains are capable of reaches speeds greater than 300 mph, and are much more energy efficient than other forms of travel.
In general, maglev trains have a magnetic track that repels other magnets placed on the train, allowing the train to float above the track. Other magnets are placed on the sides of the train and the sides of the track to keep the train on course and prevent it from leaving the track. A traveling magnetic field is then used to propel the train forward.
Maglev TrackMaglev Track
 Guidance & support magnets in the track © www.transrapid.de

 
There is currently one Maglev system open and running commercially, the Transrapid in Shanghai, China. The Transrapid is a German design that uses electromagnets in the train car and track to provide the lift and propulsion force necessary to move the train. Other designs are currently being developed as well. In Japan, the Central Japan Railway Company's JR-MLX01 train uses superconducting magnetic coils in the train instead of regular electromagnetic coils. This type of system is called an electrodynamic system. The JR-Maglev design set the current Maglev speed record at 361mph. Finally, a third design is being developed by the Lawrence Livermore National Laboratory in California. This design, called Inductrack, aims to lift and propel the train without constant electrical energy being used in the track or the train.
Inductrack


This design uses special arrangements of permanent magnets on the train and coils of wire in the track. Although a small external force is required to get the train moving at first, once the train reaches a minimum speed, the motion of the train will induce currents in the coils of wire insdie the track that will provide the lifting force needed to float the train.Therefore, no long-term power supply is needed to support the train, just its own motion. While a full model has not been built using the Induct


Shanghai - Maglev 




ELECTRICITY






1) what is electricity? Electricity is the flow of electrical charge.Electricity is the most basic part of nature because it does so many jobs for us. It powe.rs our homes,televisions,computers,and cools our homes and is a big part of the economy

2) Why is electricity important to us? Because if we had no electricity we wouldn't be able to see.And we could not do our work and if we didn't have electricity we wouldn't have computers,tv's etc..

3) How do you use Electricity? Retail and service buildings use 149 billion kWh (or 508 trillion Btu) of site electricity (electricity consumed within the building) each year. This electricity is used for a variety of different purposes, the most being used for lighting.

4) How do we use Electricity? Millions of years ago, the remains of plants and animals built up in thick layers. This decayed matter from plants and animals is called organic material -- it was once alive. Over time, the mud and soil changed to rock, covered the organic material and trapped it beneath the rock.

5) What is the history of the human uses of electricity? In March 2003 the Department created two offices to provide focus in several critical areas: the Office of Electric Transmission and Distribution (TD), which advanced the technologies needed to ensure a reliable, robust and modern U.S. electricity grid, and the Office of Energy Assurance (EA).

 6) Name two types of Electricity? (AC) and (DC) wich mean derict cerrent and Alternating cerrent.

ENERGY


What are the sources and forms that everyone talks about?


EnergyRecently, a friend of mine told me: Why state the definition of energy? People will not want to learn about that. They just stick with an energy provider and power up their houses.
In fact, that is our biggest mistake. I think that we should know what lies behind everything, in order to make the proper decision.
I strongly believe, that by the time you navigate away from this site, you will be considering of installing a set of modules on you house, and changing your energy provider too.




Significance of Behavioural Change
As much as formal initiatives and programmes have their place in the battle for a more energy efficient UAE, there also needs to be a general shift in culture by the public. Improving public perception of green issues and encouraging behaviours that support energy efficiency can contribute significantly towards the overall goal. As fuel prices increase in the domestic market, the UAE’s citizens are already adding more weight to fuel efficiency when considering what cars they will buy.
SUVs and 4x4s might still be the biggest sellers but household budgets are becoming increasingly stretched and many ordinary citizens are looking for smaller more efficient cars. Perhaps for the first time, the entire running costs of cars are being considered and the UAE’s car dealers and their suppliers are looking to accommodate this change in their customers’ attitudes. This trend is so significant that some car dealerships are seeing large year-on-year increases in sales of their smaller, more efficient models.
Car rental companies are seeing this trend also and in Dubai, at least one is making hiring a car with green credentials more appealing to a wider cross-section of the public – offering everything from the more familiar Chevrolet Volts and Nissan Leafs to the most exotic hybrid and fully electric cars available to hire or lease.
Capitalising on these trends makes both environmental and business sense but economic drivers cannot alone be left to change public behaviour. There are really simple measures that government and business should be encouraging people to take. Some may argue that switching-off computers, lights and air-conditioning at the end of the working day may save energy but is not sufficiently worthwhile promoting – voluntary measures of this sort will not impact on overall energy trends.
There is evidence however that if these behaviours are added to measures like installing energy efficient lighting, lowering thermostats and optimising EESL five-star rated air-conditioners, the energy savings really do become significant – potentially halving a building’s energy consumption.
Conserving energy may not yet be a way of life in the UAE but the rapid changes being seen there are an indicator of what is to come. Formal energy efficiency programs and voluntary measures combined will help the UAE maintain its economic strength in the region and because of this it is one agenda that will not be going away



Energy chart showing sources, interconversion, and uses.
Our sun is a major source of energy; other sources include nuclear fuels and geothermal springs. These sources can be converted into the various types of energy we use: Heat, mechanical work, and electricity. Because the conversion of heat into mechanical work cannot be 100%, some energy is always lost as heat as we use energy for residential power, industrial manufacturing, and transportation. (Image by MIT OCW.)

Course Description

This course assesses current and potential future energy systems, covers resources, extraction, conversion, and end-use, and emphasizes meeting regional and global energy needs in the 21st century in a sustainable manner. Different renewable and conventional energy technologies will be presented including biomass energy, fossil fuels, geothermal energy, nuclear power, wind power, solar energy, hydrogen fuel, and fusion energy and their attributes described within a framework that aids in evaluation and analysis of energy technology systems in the context of political, social, economic, and environmental goals. This course is offered during the last two weeks of the Independent Activities Period (IAP), which is a special 4-week term at MIT that runs from the first week of January until the end of the month, and continues into the Spring semester.

cuti & persekolahan 2013


gambar-gambar sea annemone, koala, jellyfish