ATOMIC CLOCKS

By Charles Truett

The first atomic clock came into existence in 1949. The U.S. National Bureau of standards was the home of this prototype of modern atomic clocks. The first accurate atomic clock was designed in 1955. This clock was based upon the transition of the caesium-133 atom. The discovery of this technology was the basis if the internationally agreed upon second. The United States has an official clock, an atomic clock, that is responsible for the accuracy of time throughout the country and is working in conjunction with clocks around the world to ensure that time is kept in unison across the globe.

Today we can find atomic clocks for our homes, offices, and electronic devices. These highly popular clocks can be purchased from your local retailers or from reputable online merchants who specialize in bringing you only the best, most precise timepieces around. Various styles and designs will make it easy for you to choose the atomic clock that best suits your needs. The atomic clocks used by government entities are by far the most accurate, but personal atomic clocks are highly reliable and you will be certain that you always know exactly what time it is at any given moment.

When shopping for an atomic clock, keep in mind that versions available to the general public are not suitable for scientific calculations, but instead a personal asset and a symbol of precise decisiveness. You can find an atomic clock in any price range and in many styles. An atomic clock makes a great conversation piece and will be a stylish addition to your home or office. Taste, style, and precision are what you will find when you begin your search for the perfect atomic clock. Great deals and numerous choices are a click away.

You can now buy clocks online! To view our complete and comprehensive selection of atomic clocks, please visit: amazon.com

Article Source: http://EzineArticles.com/?expert=Charles_Truett

Atomic Clock
By Wikipedia
An Atomic Clock is a type of clock that uses an atomic resonance frequency standard to feed its counter. Early atomic clocks were masers with attached equipment. Today's best atomic frequency standards (or clocks) are based on absorption spectroscopy of cold atoms in atomic fountains. National standards agencies maintain an accuracy of 10-9 seconds per day (approximately 1 part in 1014), and a precision equal to the frequency of the radio transmitter pumping the maser. The clocks maintain a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but synchronized with the passing of day and night based on astronomical observations.

History
The first atomic clock was built in 1949 at the U.S. National Bureau of Standards (NBS). The first accurate atomic clock, a cesium standard based on a certain transition of the cesium-133 atom, was built by Louis Essen in 1955 at the National Physical Laboratory in the UK. This led to the internationally agreed definition of the second being based on atomic time.

For decades, scientific-instrument companies, such as Hewlett-Packard, have been making cesium-fountain clocks for entities like NIST and USNO, at prices rivalling those of cars.

In August 2004, NIST scientists demonstrated a chip-scaled atomic clock. According to the researchers, the clock was believed to be one hundredth the size of any other. It was also claimed that it requires just 75 mW, making it suitable for battery-driven applications. This device could conceivably become a consumer product. It will presumably be much smaller, much less power-thirsty, and much cheaper to make than the traditional cesium-fountain clocks used by NIST and USNO as reference clocks. However, it is uncertain whether it will ever become a consumer product.

How they work
Frequency reference masers use glowing chambers of ionized gas, often cesium because that is the element used in the official international definition of the second.

Since 1967, the International System of Units (SI) has defined the second as the duration of 9 192 631 770 cycles of the radiation which corresponds to the transition between two energy levels of the ground state of the cesium-133 atom. This definition makes the cesium oscillator (often called an atomic clock) the primary standard for time and frequency measurements (see cesium standard). Other physical quantities, like the volt and metre, rely on the definition of the second as part of their own definitions. [1]

The core of the atomic clock is a tuneable microwave cavity containing the gas. In a hydrogen maser clock the gas emits microwaves (mases) on a hyperfine transition, the field in the cavity oscillates, and the cavity is tuned for maximum microwave amplitude. Alternatively, in a cesium or rubidium clock, the gas absorbs microwaves and the cavity contains an electronic amplifier to make it oscillate. For both types the atoms in the gas are prepared in one electronic state prior to filling them into the cavity. For the second type the electronic state of leaking atoms is detected and the cavity is tuned for a maximum of detected state changes.

This adjustment process is where most of the work and complexity of the clock lies. The adjustment tries to correct for unwanted side-effects, such as frequencies from other electron transitions, temperature changes, and the "spreading" in frequencies caused by ensemble effects. One way of doing this is to sweep the microwave oscillator's frequency across a narrow range to generate a modulated signal at the detector. The detector's signal can then be demodulated to apply feedback to control long-term drift in the radio frequency. In this way, the quantum-mechanical properties of the atomic transition frequency of the cesium can be used to tune the microwave oscillator to the same frequency, except for a small amount of experimental error. When a clock is first turned on, it takes a while for the oscillator to stabilize.

In practice, the feedback and monitoring mechanism is much more complex than described above.
Historical accuracy of atomic clocks from NIST.
Historical accuracy of atomic clocks from NIST.

A number of other atomic clock schemes are in use for other purposes. Rubidium standard clocks are prized for their low cost, small size (commercial standards are as small as 400 cm³), and short term stability. They are used in many commercial, portable and aerospace applications. Hydrogen masers (often manufactured in Russia) have superior short term stability to other standards, but lower long term accuracy.

Often, one standard is used to fix another. For example, some commercial applications use a Rubidium standard slaved to a GPS receiver. This achieves excellent short term accuracy, with long term accuracy equal to (and traceable to) the U.S. national time standards.

The lifetime of a standard is an important practical issue. Modern Rubidium standard tubes last more than ten years, and can cost as little as US$50. Cesium reference tubes suitable for national standards currently last about seven years and cost about US$35,000. The long-term stability of hydrogen maser standards decreases because of changes in the cavity's properties over time.

Modern clocks use magneto-optical traps to cool the atoms for boosted precision

Notebook GPS

Best PC Pocket GPS
By Dan Ayala

Stop Getting Lost

One of the greatest uses for a pocket pc is for gps navigation. Now all those people who continually get lost can find their way anywhere with the various types of gps navigation software available. No longer will they have the excuse of not wanting to ask for directions. The directions are easily accessible from their palm pilot.

The best pocket pc gps software has a gps receiver with it. This allows you to receive constant updates. Many of the best software products for your ipaq have some other great features, too. Some of these features include detailed maps for roads and streets in the U.S., Canada and Europe. These maps can be downloaded to and from your computer and often allow you to enter personalized information.

Other gps navigation software offers topographical maps, aviation maps and marine maps. For whatever kind of travel you do, there is a gps system for your pocket pc that will work splendidly. You no longer have to worry about being lost hiking in the mountains, flying a small personal aircraft or piloting your own boat.

The best gps software packages have extremely detailed voice guidance to keep your eyes on the road instead of on your pda. This safety feature should impress even the most careful driver.

Having gps navigation software on your pocket pc makes the world a much smaller, safer place to be and a heck of a lot easier to navigate. So, find the best pc pocket gps for you and never get lost again.

Buy PockPC, Notebook and GPS at amazon.com.

Article Source: http://EzineArticles.com/?expert=Dan_Ayala

GPS Reviews

The Garmin 350 is a great GPS for the price "now". My friend purchased the same model during Jan/Feb-07 for over $900 CDN. It was very simple to use and really didn't require much instruction. After a few minutes of playing with it, the system was able to locate my position and it was ready to go. After using it for a few weeks...I love this GPS. I decided to order the Gilsson External Antenna (Model MCX with 3fts wire)to increase my reception around the town.

Great price at Amazon....even my wife "The Living GPS" was impress by this little gadget.

GIS for Real Estate

By Harry E. Davis

GIS stands for "Geographic Information Systems." A geographic information system is used for capturing, storing, analyzing and managing data and associated attributes which are referenced to a given point or place. Many local governments have begun to establish these systems for use within their borders and a GIS provides a central access point for geographic information not only for government employees, but also for web users. Austin, Texas has had a sophisticated GIS online for several years.

One advantage for a government entity in setting up a working GIS site is that it provides customers an online way to get various types of information on the web without calling or having to drop by the office, thereby freeing up employees for other tasks. The consumer gets an advantage by being able to view a lot of maps, such as zoning maps, online instead of having to purchase one.

GIS is a great tool for real estate agents, appraisers, buyers and anyone else with a need to look up information about a property, and GIS is becoming more widespread every day. If you live in a medium to large size city, chances are very good that your local city or county planning department has a working GIS right now. Even many small towns have them.

GIS enables the visitor and the real estate professional to view zoning maps, parcel maps, flood maps, aerial photos, and a variety of other information which can be viewed separately or as a grouping of layers on the same map. Most GIS systems provide an address search capability. For some types of properties it may be necessary to zoom in from a map of a larger area. Tools to zoom in and out are always provided.

In an example situation, suppose you search for a home by address and find it on the map. You can then choose from several map layers to add to it from a menu, such as zoning, parcel maps, bodies of water, and more. If you choose to overlay flood zone maps, you will be able to tell if the home lies with a flood plain. This gives the user a way to know if the home is likely to require flood insurance. If you want to know the specific zoning for the home, you can choose to have that map layer added on top. These map "layers" are mostly transparent, meaning that the original map will still be visible.

The local city planning department GIS systems and their corresponding menu systems vary according to the design and the provider, but I have accessed several in my area and found them to be more or less the same in terms of how they operate and they types of information they provide. The beginning GIS user may find these online systems a little confusing at first, but a few experiments should help you to find your way around. These systems continue to evolve to make them easier for nontechnical users to operate. The wealth of useful information they provide makes them well worth the effort to learn.

To locate a GIS for your city, go to your favorite search engine and type in the name of the city and GIS, such as " Austin GIS" in the search box. If you don't find your local GIS this way, go to the city or county web site and look for it there or just contact their office and find out if one exists and where to find it.

Harry E. Davis is a Texas state certified residential real estate appraiser in business since 1975 and serving the Austin Texas metro area. His web site is located at Austin Texas Appraiser. Services are available in other Texas cities at El Paso Texas Appraiser and Fort Worth Texas Appraiser

Article Source: http://EzineArticles.com/?expert=Harry_E_Davis

Raster to Vector Conversions

By Rohini Sood

With rapidly increasing technologies more and more companies are searching for new ways to gain a lead in the market, raster to vector (R2V) conversion is becoming a standard of expectation. Raster to Vector conversion also known as R2V caters to the diversified fields ranging from commercial to industrial. More than 60 countries use R2V for mapping and GIS data conversion applications. Architectural, engineering, construction, electrical and house plans are all regulars of the raster to vector conversion. The raster to vector conversion can be applied to convert data or image into vector format. The advantages of raster to vector (R2V) conversion include: A vector image has no jaggedness, no loss in detail and can be printed at any resolution or any size.

This vector image can be scaled up or down without any loss in quality.

Also the archive of the vector artwork can be used for manuals, brochures, newspapers and a host of other areas.

Raster to vector conversions enables you to convert technical drawings, maps logos and any other graphics from raster to vector formats, for easy archiving and instant access. Raster to vector (R2V) procedure can be used to process charts, drawings, maps, schemes and other similar images.

Applications:

Raster to vector conversion of Technical Drawings (AEC)

Raster to vector conversion of House plans

Raster to vector conversion of GIS (CAD)

Raster to vector conversion of Blueprints

Raster to vector conversion of Logos

Vectorization for website applications

Vectorization for Graphic Design purposes

One of the many ways to achieve the raster to vector conversion can be recreating the vectorized output using AutoCAD (DWG, DXF), MicroStation (DGN), Adobe Illustrator (AI), CorelDraw (CDR), VectorWorks, etc.

Article Source: http://EzineArticles.com/?expert=Rohini_Sood

Digital Globe

By Peter Emerson
Globes are the spherical version of a map. Their spherical shape allows them to represent the earth perfectly. Globes were always in used as navigational tools as well as to understand various earth’s processes and phenomena.

The earliest globes were traced to the fifteenth century. Like maps, globes also show accurate directions, dimensions, distances, shapes and sizes of all the countries in the world. Most globe-makers use high quality geographic research and cartographic abilities to design globes. They are also updated regularly to take note of any changes in the world’s political, social, or environmental conditions.

Digital globes are those which use advancements in digital technology for representing the earth better. They have digital images over and inside the screen that keep changing as per the user’s requirements. The images, derived from satellite images, are made to appear on the screen, which is similar to a picture screen of a television. There are also digital raised-relief globes with clearly defined mountain ranges and water bodies. There are also celestial digital globes available. However, digital globes are not generally meant for commercial applications.

Virtual globes are also digital globes that can be viewed on the computer or any other interface. These may be simple globes used for classroom teaching, or they can be highly technologically advanced. Some virtual globes use state-of-the-art technology like satellite imaging and multiple GIS databases for real-time coverage. Virtual globes can be online or offline. These days, the application of virtual globes has become so common that they are also being fitted in cars in order to make navigation easier for the driver. They can provide detailed information, right down to a street’s name.

Another kind of digital globe is the hyperglobe that uses virtual reality to present spatial effects. These are used for visually depicting certain geographic processes and phenomenon such as the earth’s inclination, space travel, and satellite technology, through three-dimensional geoid visualization, animation, and real-time presentations. These also have interactive cartometric tools for making the data globally available.

Globes provides detailed information on Globes, World Globes, Digital Globes, Snow Globes and more. Globes is affiliated with Fiberglass Flagpoles.

Article Source: http://EzineArticles.com/?expert=Peter_Emerson

Interactive Mapping

By Joe Miller

Interactive mapping is a visual display medium which allows graphing, mapping, and even conversion to PDF of any type of information. This technology is used by national government agencies, airlines, chambers of commerce, ski resorts, and countless corporations to make information accessible and interactive to whomever they present the information.

Phone and credit card companies use interactive mapping to show billing information. Companies use it in reporting, forecasting, sales and marketing, and display retirement plan information to its employees, using Dashboard, PopChart, Optimap, and Highwire features for interactive and simple information presentation and utilization, even on a pocket PC.

What can Interactive Mapping Do for You?

Interactive mapping involves so much more that just maps. Dashboard, Popchart, Optimap, and Highwire provide interactive information in virtually any format: charts, graphs, pie charts, tables, etc.

In addition to the examples given above, here are additional ways to use interactive mapping.

Retail stores can track revenue, returns, and customer information across geographical demographics.

Manufacturers can track processing times along the supply chain.

Electric companies can track overall usage in geographic regions.

The CIA World Factbook collects and presents geographical, population, and even cell phone usage across the world with interactive mapping.

Airlines track cancellations, fares, purchases, flight loading, and seating.

Land developers find geographical survey of longitudes and latitudes for cities anywhere in the United States.

Businesses track receivables, payables, inventory, and sales.

Companies break down sales reports according to product.

Corporations publish stock reports.

Marketing statistical personnel create charts and graphs, using functions.

Doctors find cancer rates across the United States.

Consumers track orders and receipts.

Students view documents like the US Constitution, connecting to notes, comments, and references embedded in the text.

Is Interactive Mapping Technology Compatible with Other Technology?

Yes. Interactive mapping has found a way to work hand in hand with technologies companies already use. Interactive mapping is also adaptable to PDF. Some examples of technologies with which interactive mapping tools can interface include HTML, FLASH, EMF, WAR, and XML.

Business, government, and educational reports and informational presentations are constantly being created and published with a variety of technologies and applications already available on the market. Documents created with the same applications can be teamed up with interactive mapping tools to create a simple display of information with which companies and consumers alike can interact.

Article Source: http://EzineArticles.com/?expert=Joe_Miller

GIS Overview

Overview of GIS
Author : www.gisdevelopment.net

Introduction
Geographic Information System (GIS) is a computer based information system used to digitally represent and analyse the geographic features present on the Earth' surface and the events (non-spatial attributes linked to the geography under study) that taking place on it. The meaning to represent digitally is to convert analog (smooth line) into a digital form.

"Every object present on the Earth can be geo-referenced", is the fundamental key of associating any database to GIS. Here, term 'database' is a collection of information about things and their relationship to each other, and 'geo-referencing' refers to the location of a layer or coverage in space defined by the co-ordinate referencing system.

Work on GIS began in late 1950s, but first GIS software came only in late 1970s from the lab of the ESRI. Canada was the pioneer in the development of GIS as a result of innovations dating back to early 1960s. Much of the credit for the early development of GIS goes to Roger Tomilson. Evolution of GIS has transformed and revolutionized the ways in which planners, engineers, managers etc. conduct the database management and analysis.

Some Interesting Links :
What is GIS ?
A complete compilation of information on GIS
GIS guide to Good Practice
A brief introduction to GIS and Archaeology
An Introduction to GIS in Real Estate
Gil Castle's final draft of the real estate column appearing in Real Estate Issues, August 1995
A Brief Introduction to GIS Technology
Enhancing Community Capacity to use Spatial Information
Defining GIS
A GIS is an information system designed to work with data referenced by spatial / geographical coordinates. In other words, GIS is both a database system with specific capabilities for spatially referenced data as well as a set of operations for working with the data. It may also be considered as a higher order map.

GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps. These abilities distinguish GIS from other information systems and make it valuable to a wide range of public and private enterprises for explaining events, predicting outcomes, and planning strategies. (ESRI)

A Geographic Information System is a computer based system which is used to digitally reproduce and analyse the feature present on earth surface and the events that take place on it. In the light of the fact that almost 70% of the data has geographical reference as it's denominator, it becomes imperative to underline the importance of a system which can represent the given data geographically.

A typical GIS can be understood by the help of various definitions given below:-
A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on Earth
Burrough in 1986 defined GIS as, "Set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes"

Arnoff in 1989 defines GIS as, "a computer based system that provides four sets of
capabilities to handle geo-referenced data : data input data management (data storage and retrieval) manipulation and analysis data output. "

Hence GIS is looked upon as a tool to assist in decision-making and management of attributes that needs to be analysed spatially.

All About GIS

Test content7