When people talk about “a GPS,” they usually mean aGPS receiver. The Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). The U.S. military developed and implemented this satellite network as a military navigation system, but soon opened it up to everybody else.

Each of these 3,000- to 4,000-pound solar-powered satellites circles the globe at about 12,000 miles (19,300 km), making two complete rotations every day. The orbits are arranged so that at any time, anywhere on Earth, there are at least four satellites “visible” in the sky.

A GPS receiver’s job is to locate four or more of these satellites, figure out the distanc e to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration. Trilateration in three-dimensional space can be a little tricky, so we’ll start with an explanation of simple two-dimensional trilateration.

The Global Positioning System has a clever, effective solution to this problem. Every satellite contains an expensive atomic clock, but the receiver itself uses an ordinary quartz clock, which it constantly resets. In a nutshell, the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy. In other words, there is only one value for the “current time” that the receiver can use. The correct time value will cause all of the signals that the receiver is receiving to align at a single point in space. That time value is the time value held by the atomic clocks in all of the satellites. So the receiver sets its clock to that time value, and it then has the same time value that all the atomic clocks in all of the satellites have. The GPS receiver gets atomic clock accuracy “for free.”

When you measure the distance to four located satellites, you can draw four spheres that all intersect at one point. Three spheres will intersect even if your numbers are way off, but four spheres will not intersect at one point if you’ve measured incorrectly. Since the receiver makes all its distance measurements using its own built-in clock, the distances will all be proportionally incorrect.

The receiver can easily calculate the necessary adjustment that will cause the four spheres to intersect at one point. Based on this, it resets its clock to be in sync with the satellite’s atomic clock. The receiver does this constantly whenever it’s on, which means it is nearly as accurate as the expensive atomic clocks in the satellites.

"The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big."
— Richard Feynman, Nobel Prize winner in physics

Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced.

In its original sense, ‘nanotechnology’ refers to the projected ability to construct items from the bottom up, using techniques and tools being developed today to make complete, high performance products.

What is nanotechnology all about?

Nanotechnology is the engineering of tiny machines — the projected ability to build things from the bottom upinside personal nanofactories (PNs), using techniques and tools being developed today to make complete, highly advanced products. Ultimately, nanotechnology will enable control of matter at the nanometer scale, using mechanochemistry. Shortly after this envisioned molecular machinery is created, it will result in amanufacturing revolution, probably causing severe disruption. It also has serious economic, social, environmental, and military implications.

Much of the work being done today that carries the name ‘nanotechnology’ is not nanotechnology in the original meaning of the word. Nanotechnology, in its traditional sense, means building things from the bottom up, with atomic precision. This theoretical capability was envisioned as early as 1959 by the renowned physicist Richard Feynman.

Four Generations of nanotechnology:

Mihail  (Mike ) Roco  of the U.S. National Nanotechnology Initiative has described four generations of nanotechnology development (see chart below). The current era, as Roco depicts it, is that of passive nanostructures, materials designed to perform one task. The second phase, which we are just entering, introduces active nanostructures for multitasking; for example, actuators, drug delivery devices, and sensors. The third generation is expected to begin emerging around 2010 and will feature nanosystems with thousands of interacting components. A few years after that, the first integrated nanosystems, functioning (according to Roco) much like a mammalian cell with hierarchical systems within systems, are expected to be developed
It is difficult to say for sure how soon this technology will mature, partly because it’s possible (especially in countries that do not have open societies) that clandestine military or industrial development programs have been going on for years without our knowledge.

Is nanotechnology bad or good?

Nanotechnology offers great potential for benefit to humankind, and also brings severe dangers. While it is appropriate to examine carefully the risks and possible toxicity of nanoparticles and other products of nanoscale technology, the greatest hazards are posed by malicious or unwise use of molecular manufacturing. CRN’s focus is on designing and promoting mechanisms for safe development and effective administration of MM.

We cannot say with certainty that full-scale nanotechnology will not be developed with the next ten years, or even five years. It may take longer than that, but prudence—and possibly our survival—demands that we prepare now for the earliest plausible development scenario.

The microprocessor, (or CPU), is the brain of the computer. The picture above shows a slot 1 processor with heatsinks and a fan, which prevent it from overheating. Below is the processor without the heatsinks and fan, being inserted into a slot 1 motherboard connection. Slot 1 processors have the microprocessor and level 2 cache memory mounted on a circuit board, (or card), which is enclosed inside of a protective shell.The enclosed slot 1 processor card contains the central processing unit, (or CPU), with its level 1 cache memory. The central processing unit also contains the control unit and the arithmetic/logic unit, both working together as a team to process the computer’s commands. The control unit controls the flow of events inside the processor. It fetches instructions from memory and decodes them into commands that the computer can understand. The arithmetic/logic unit handles all of the math calculations and logical comparisons. It takes the commands from the control unit and executes them, storing the results back into memory. These 4 steps, (fetch, decode, execute, and store), are what’s called the “machine cycle” of a computer. These 4 basic steps are how the computer runs each and every program. The microprocessor’s level 1 cache memory, is memory that is contained within the CPU itself. It stores the most frequently used instructions and data. The CPU can access the cache memory much faster than having to access the RAM, (or Random Access Memory). Below is a picture of what’s inside of a Pentium 3 processor. The control unit, arithmetic/logic unit, and level 1 cache are contained within the center CPU chip. Level 2 cache memory is visible on the right-hand side of the processor card.

Level 1 cache memory is memory that is included inside of the CPU itself. It is usually smaller and faster than level 2 cache memory. Level 2 cache memory is memory between the RAM and CPU. It is used when the level 1 cache memory is full or is too small to hold the intended data. Originally it was not directly on the CPU chip itself. *Read the update at the bottom of this page.* The photo above shows level 2 cache memory on the processor card, beside the CPU. Below are two photos of a CPU. The photo on the bottom is a view of the CPU chip from the outside. The photo on the top is a large map of the inside of the CPU, showing the different areas and what their function is. See if you can find the areas that fetch, decode, and execute the instructions. Can you also find the level 1 cache areas that store information? The pipelined floating point area, logic areas, and superscalar integer execution units area are part of what? Did you guess the arithmetic/logic unit? If so, you’re right!

At the top you can also see the clock driver. The clock driver is what times, or sets the pace, for the computer. The clock’s speed, is how CPUs are rated. Each machine cycle consists of two beats. Each beat the control unit fetches and decodes data, which is called the “instruction cycle.” At the same time the arithmetic/logic unit executes and stores data, which is called the “execution cycle.” The speed of a clock is rated by how many beats per second it can accomplish. 1 billion beats per second is referred to as 1Ghz. For every beat, (except the very first), a machine cycle is completed. Common CPUs available today perform at 3Ghz and faster. This means that a 3Ghz CPU can execute 3,000,000,000 instructions in a single second!

Very few people know about alternative ways of charging their mobile phones and other electronic gadgets. However, it is possible to charge these gadgets without having to rely on electricity. For instance, unknown to many, solar cell phone chargers are available in the market.

But how do solar cell phone chargers work, exactly, and how efficient are these environmentally-friendly products?

The design or appearance of these chargers often varies depending on the brand or model, but they are generally lightweight; a few of them are even small enough to fit inside your pocket. These charger has a small solar panels that stores energy.

A few models have panels that look like windmills, although most have more ergonomic designs for easy—and even chic—handling. Some models even allow you to simply stick the panels on a window to generate energy from the sunlight. Others can be placed around your arm or even a bicycle.

Obviously, this means you can bring the charger anywhere. Many mobile phone owners who have this charger keep it as an alternative means to charge a phone in case of a power outage or when there is no possible source of electricity within their vicinity.This kind of technology is no longer new. The photons are converted into electric current by the solar panels or cells, which agitate the light particles and turn them into electrons.

1° Take Amp/hour rating of the battery and Divide by the charger rating (in amperes) (*) and then add about 10% for the extra time to top off the battery,
(*) “Watt = Ampere x Volts” “Ampere= Watt/Volts” “Volt= Watt/Ampere”

(Example): To Calculate how much time You’ll need to charge the battery with a 15 Watt solar charger You’ll need:
1. Calculate the Ampere per hour of the charger: 15 Watts /12 Volts = 1,25 Amperes
2. Calculate the division: 50 amp hours / 1,25 amperes = 40 Hours of direct sunlight
3. Add 10%: 4 hours

Enrico Forte is the editor of the blog “12 Volt Solar Panels”. It’s a free online resource to help people get detailed info on Solar Cell Phone Chargers , reviews from the hottest manufacturers and interviews with industry experts.

The trick when launching a satellite is to get it high enough to do its job without losing the capsule to outer space. It’s a delicate balance of push and pull, accomplished by the inertia of the moving object and the Earth’s gravity. If you launch a satellite at 17,000 mph, the forward momentum will balance gravity, and it will circle the earth. On the other hand, if the satellite is launched faster then 23,500 mph, it will leave the gravitational pull of the Earth.

Why does a satellite stay in orbit?

Due to the balance of two factors:

1. velocity, or the speed at which it would travel in a straight line, and
2. the gravitational pull between the Earth and the satellite.

To illustrate this principle, attach a small weight or a ball to a string and swing it around in a circle. If the string were to break, the ball would fly off in a straight line but because it is tethered (like gravity tethers a satellite), it orbits you.

Imagine that you could climb an imaginary mountain whose summit pokes above the Earth’s atmosphere (It would be about ten times higher than Mt. Everest). If you threw a baseball from the mountain top, it would fall to the ground in a curving path. Two motions act upon it: trying to go in a straight line and falling toward Earth. The faster you throw the ball, the farther it will go before it hits the ground. If you could throw the ball at a speed of 17,000 mph, the ball wouldn’t reach the ground. It would circle the Earth in a curved path; it would be in orbit. (It would be traveling at 5 miles per second and take about ten minutes to cross the United States.) This is the speed needed to put satellites into orbit, which is why the Space Shuttle and other satellites require such powerful boosters.