Who Invented the Refrigerator

Refrigerators are an essential part of every modern kitchen. While just about every home makes use of a refrigerator, most consumers know nothing about the history of refrigeration and the invention of the refrigerator. The gradual creation of the modern refrigerator actually spans a process that began in the 18th century and culminated with the work of German engineer Carl von Linden in 1876.

The first efforts that eventually led to the modern refrigeration process that continues to form the basis for the fridges that grace kitchens all over the world today. William Cullen of the University of Glasgow first developed a process to create an artificial cooling medium in 1748. At the time, there did not appear to be much interest in applying the medium to use in commercial or home applications, so the process created little in the way of interest beyond the scientific community. It would take the better part of a century before someone would apply the basic principles discovered by Cullen and create a design for a refrigerating machine. 

Created in 1804, the design was the work of an American inventor by the name of Oliver Evans. However, no working prototype appeared until 1834. At that time, Jacob Perkins built a refrigeration machine that is often thought to be the forerunner of the modern refrigerator. A decade later, John Gorrie designed what is thought to be the first practical refrigerator. In 1844, Gorrie, a physician in the United State, constructed a working unit based on the design of Oliver Evans. Gorrie created the unit as a means of cooling the air in facilities he set aside for patients who were diagnosed with yellow fever. Many people credit Gorrie as being the individual who for all practical intents and purposes invented the refrigerator. 

Carl von Linden discovered and patented an improved method of liquefying gas in 1876, which made the process of manufacturing refrigerator models practical. Making use of such gases as ammonia, sulfur dioxide and methyl chloride, the new process formed the standard for cooling agents until the late 1920’s. By then, a number of accidents related to the use of these substances as cooling agents convinced manufacturers that a more stable element was needed. This effort led to the development of freon, which provided the standard for cooling agents for the bulk of the remainder of the 20th century, until the substance was leaked to damage to the ozone layer. 

From the simple working model created by John Gorrie in 1844 to the modern fridge units of today, the refrigerator has become one of the appliances that is an integral part of our lives. From storing our favorite foods to providing refreshing ice, the refrigerator is one device that most of us would not want to live without.

How Does a Television Work

A television produces a series of tiny dots on a screen that, when seen as a whole, appear as an image. Older televisions rely on a cathode-ray tube to produce images, and operate with an analog signal. As technology has advanced and broadcast signals transitioned from analog to digital, plasma and LCD (liquid crystal display) televisions were created. These TVs are more compact and have crisper pictures than their cathode-ray counterparts because they use a thin grid of pixels to create images rather than a vacuum tube.

The Eyes and the Brain

Most kinds of television work from the same basic principle. The tiny dots of light produced on the TV screen, called pixels, flash according to a specific pattern provided by the video signal. A person's eyes transmit this pattern to the brain, where it is interpreted as a recognizable image. The television set refreshes these patterns hundreds of times per second — faster than the human eye can see — which gives the illusion of movement.

The Cathode-Ray Tube

The cathode-ray tube (CRT), the oldest version of the television, consists of a vacuum tube with a narrow end and a wide end. The narrow end contains an ion gun, which shoots out a series of charged particles of electricity. A series of electromagnets guide the particles to specific points on the wide end of the tube, the screen that viewers look at. Phosphors, substances that light up when a charged electrical particle hits them, coat the screen's inner surface. The ion gun essentially sprays the image at the screen, much like a paint gun sprays paint onto a surface.

Different kinds of phosphors produce different colors, but for color television, only red, blue, and green are needed. Using these colors in various combinations and intensities can create all the colors the human eye can see. As energy travels from the ion gun to the phosphors, it is filtered to strike the exact point on the screen needed to produce a specific hue. In combination, all of these colored pixels create a color image.

Cathode-ray tubes are quite heavy due to the large amount of glass they contain, and relatively inefficient, especially when used in large-screen televisions. For this reason, new technologies were developed to make lighter sets with crisper images. In addition, the development of high definition (HD) digital broadcast signals made bigger screens more popular since the images were of higher quality. Plasma and LCD televisions were created in response.

The Plasma Screen

A plasma screen television consists of a number of tiny cells filled with neon and xenon gases. Each cell is linked to an electrode, which, when fired, excites the gases contained in the cell. The gases emit charge particles, much like the ion gun, that interact with phosphors coating the glass inside each cell. The phosphors light up, creating the image seen on the television screen. The large number of cells in a plasma screen makes for a great number of pixels, rendering a clearer and brighter image.

Compared to other technologies, plasma TVs produce some of deepest blacks, which means that the contrast ratio is very high. They also have very high refresh rates, so images with a lot of motion don't blur as they can on other televisions. If the image remains static, however, it can burn into the screen, creating a permanent discoloration; this is more common in older plasma TVs, and can also occur with CRT screens. Plasma screens can be set to be very bright, which requires a lot of electricity. They also tend to be thicker than LCD televisions, although much thinner than CRTs.

The LCD Screen

LCD televisions also use cells to create images. Rather than exciting gases as plasma TVs do, however, the cells contain a set of red, blue, and green filters covered by a layer of liquid crystals sandwiched between two pieces of glass. Depending on the display type, each cell is linked to either electrodes or thin film transistors (TFT), which trigger the necessary cells to create the image. A backlight — most often cold-cathode fluorescent lamp — lights up the screen so the image can be seen.

While LCDs are very light and thin, they are subject to "dead" pixels, where one or more cells on the screen do not change. Viewing LCD screens from an angle can also lower the picture quality. They have slower response times than plasma or CRT televisions as well, so images can "ghost" or blur in movement.

More recent versions of the LCD television use light-emitting diodes (LEDs) as the light source rather than cold-cathode fluorescent lamps. LED televisions require less electricity than regular LCD screens, and take up even less space. Also, LEDs generally emit a brighter white light, making these screens especially vivid.

What Is Cell Phone Etiquette

Cell phones have become an unavoidable part of modern life for many people, but their presence in so many places can lead to situations in which users are inconsiderate of others. Just as general rules of etiquette vary among cultures, so do rules of cell phone etiquette. Still, some basic principles cross cultural norms — common sense and courtesy are the cornerstones of polite cell phone use. Respecting public and personal space, maintaining privacy, and not disturbing others are some general principles a person should keep in mind when using a mobile phone.

Public vs. Private Use

Cell phone etiquette is usually at its most important in public spaces, where one loud talker can disturb a large number of people. How a person uses his or her phone in more private situations matters too, however, to those who are concerned with being considerate. Many people find it rude when someone takes a cell phone call on a date or during a private social engagement with others. Along the same lines, it's usually thought to be inconsiderate to take a call in the middle of a conversation; if the caller were there in person, he or she would likely wait to politely interrupt at a more appropriate time. When in a small group or one-on-one situation, it's best for someone receiving the call to not pick up unless it's an emergency.

Focus on the Situation, Not the Call

Public settings such as restaurants, waiting rooms, and subways are usually bad places for casual cell phone conversations. Unless the user is expecting an important call, it would be best to put the ringer on vibrate or silent mode and let any calls that do not need to be answered immediately go to voice mail. This is not only more considerate to other people in the public space, but it also helps the caller maintain his or her privacy by not divulging personal information in public.

It is also generally considered poor cell phone etiquette to stay on the phone when dealing with cashiers or customer service people. If using the phone in a supermarket or other store, the person should hang up before going to the checkout lane. In a casual restaurant, it's usually considered impolite to both the counter staff and the person on the other end of the line to stop in the middle of a conversation to place an order.

Although cars are usually considered private spaces, taking a call while driving is usually not a good idea. A number of jurisdictions ban cell phone use while driving unless a hands-free system is used. Even when a driver does not have to physically hold the phone, however, studies suggest that drivers who talk while they drive tend to focus less on the road and other cars and more on the conversation. Most calls can wait, but if one can't, it is safer for drivers to pull over before answering.

Important Phone Calls that Can't Wait

If the cell phone user thinks a call might be important, he or she should try to step outside or find a secluded area to take or return a call. For urgent calls that cannot be missed, polite cell phone users should try to keep their voices low and the conversations brief. If the call interrupts a conversation, it's best for the person to apologize before stepping away to answer.

Cell phones typically have sensitive microphones that can pick up a soft voice while blocking out ambient noise, so yelling into a cell phone is usually not necessary. When people are nearby, polite cell phone users try to keep their voices low and the tone unemotional and even. Arguing or airing dirty laundry in public is almost universally considered to be poor cell phone etiquette.

Maintaining a distance of at least 10 feet (3 meters) from the nearest person when talking on a cell phone is usually a good idea. No matter how quiet the conversation, if a person is standing too close to others, it may force them to overhear what is being said. If it's necessary for a person to speak loudly to be heard by the person he or she is speaking to due to a noisy location, it's probably not a good place to be taking the call.

Places Where the Phone Should Always Be Turned Off

In almost all cases, phones should be turned off in movie theaters, playhouses, observatories, or any other public place where an audience's attention is focused on a performance or event. A ringing phone or a conversation can be very disturbing to other audience members, who have often paid money for the experience. In some cases, performances have been stopped in progress as the performers wait for an audience member to leave or silence his or her phone.

Phones should be turned off anywhere in which silence is important and disruptions should be kept to an absolute minimum. This includes courthouses, libraries, places of worship, doctor's offices, weddings, and funerals, where a ringing phone could indicate a lack of respect. It's also best to turn off a phone during a job interview, as it can suggest that the person being interviewed is more concerned with personal issues than the job.

Ringtones

Loud and distinctive ringtones are good for catching the phone owner's attention, but they can be a major distraction to other patrons in a restaurant or theater. If a phone must be left on in a public space, the owner should put the ringer on silent or vibrate whenever possible to create the least disturbance. Turning the volume down or even changing the ringtone to one that is more subtle — such as the sound of bells ringing rather than the latest pop song — may also cause less of an interruption.

Texting and Surfing the Web

Using a smartphone to text someone or look something up online is usually appropriate in public spaces, as long as doing so does not disturb others. Smartphones often have very bright screens, and can even be used as flashlights in some cases, so using them in a dark environment like a movie theater can be very distracting. Watching videos or playing music without headphones is also likely to be a disruption in any public space, and should be avoided. Many smartphones also include games, which should only be played in public if they do not include loud sound effects or are likely to result in the player making a lot of physical movements or vocal reactions. 

Just like taking a phone call in the middle of a conversation would likely be considered impolite, focusing on the phone's screen to check sports scores or email while talking to others is usually bad cell phone etiquette. If an email or text must be responded to, the cell phone user should apologize and excuse himself to do so privately. Texting or surfing the Internet should never be done while driving.

What is Wiselink

Wiselink™ Pro is a Samsung® technology built into some of their large-screen television models. These models are equipped with a Universal Serial Bus (USB) port to accommodate external storage devices such as flash drives, flash card readers, and MP3 players. Using Wiselink, one can play sound files, view digital photographs or watch multimedia clips or movies. Function varies between original Wiselink and Wiselink Pro, and might also vary between models, depending on which flavor of Wiselink is incorporated.

To use Wiselink, simply plug a device into the USB port then switch the television to the Wiselink mode. This mode interacts with the USB port by providing various kinds of controls and options. For example, one can navigate through simple menus to engage a slide projector function to view a folder of vacation photos in JPEG format.

With the television at the heart of today’s entertainment center, the Wiselink port also allows easy access to the attached multi-channel, surround sound system. MP3 music players with the ability to hold one’s entire music library can be played through the best system in the house without need of a proprietary external speaker system. However, Samsung’s website states that Wiselink does not support the iPod®. To get around this, non-proprietary MP3 players are very inexpensive and could be used in the iPod's stead for this purpose.

Samsung’s Wiselink Pro also supports video codecs: MPEG1, MPEG2 PS/TS and MPEG4/H.264, making it possible to watch home movies downloaded from the digicam to flash storage devices. Without the USB port, one either has to drag out audio and video cables to connect the movie camera directly via auxiliary ports on the television (not always conveniently located), or burn movies to a compact disc or DVD. USB conveniently allows for more spontaneity in sharing holiday, wedding, birthday, graduation or vacation movies with friends and family. 

If you’ve downloaded purchased movies or television programs to your PC, you can copy them to a memory stick and pop the stick in the USB port to watch these shows on your entertainment center. Never mind the expense and hassle of buying blank DVDs and taking the time to burn each program or movie to disk. With Wiselink your movie library can remain in a convenient, portable file format.

Samsung televisions and Wiselink might be upgradeable through firmware. Supported formats might also change with time, as could other features of this interoperable technology.

What Is a USB Dongle

The Universal Serial Bus (USB) port is a small connector that allows a data cable to be attached so that, for example, pictures can be passed from a digital camera to a computer. On desktops, laptops, printers and other hardware, the USB port also allows for expanded functionality. Many hardware devices smaller than a pack of gum are made with one end designed to slip into the USB port. These devices are called USB dongles and can add features to the computer or machine that were not built in by the manufacturer.

A storage or memory USB dongle, also called a memory stick, provides a convenient means to pass files between computers or devices. The memory stick contains a rewritable solid-state memory chip that does not require power to retain its contents. As capacities have grown and price has dropped, these portable, plug-and-play storage drives have replaced floppy disks and even compact disks for exchanging files and archiving data.

Another type of USB dongle can add WiFi® functionality to a computer to provide wireless Internet connectivity. Most desktop computers can accommodate internal WiFi cards, but laptops and notebooks rely on external gadgets to increase features. The USB WiFi dongle comes in many models with the most basic model working with operating system software to locate nearby wireless networks in order to share access, commonly within the home or office.

A WiFi finder or scanner also comes in the form of a USB dongle, allowing a person to scan for free public hotspots while mobile. This type of USB dongle features LEDs that light without having to boot the laptop, indicating a wireless network has been detected. A series of LEDs can indicate signal strength, allowing one to glance at the dongle to see instantly if accessibility is increasing or decreasing. Different colored LEDs might also specify encrypted or unencrypted networks.

If you require Bluetooth® a personal area network (PAN) used to wirelessly connect your digital devices to each other — consider a USB Bluetooth® dongle. Bluetooth® has become increasingly useful for passing data between cell phones and computers, for syncing personal digital assistants (PDAs) to laptops, and for sharing files between laptops and desktops, to name just a few benefits of the technology. The advantage of Bluetooth® over other types of networking is that it is easy to activate and use with virtually no networking experience required, and it eliminates the need to haul various cables around. 

If you spend a lot of time on a laptop, you might want to make your printer and laptop Bluetooth®-enabled. By doing so you can wirelessly link the two machines in a few seconds to send print jobs to the printer without having to move the laptop to the printer and attach a cable. Newer printers feature a USB port that can be used with a Bluetooth® USB dongle, but other types of Bluetooth® adapters are also available if a USB port is not present.

Company employees might be familiar with the proprietary USB dongle that acts as a security token to authenticate software in order to protect it from use by unauthorized persons. This type of dongle might also verify credentials or supply a password to a Virtual Private Network (VPN) for field personnel, for example, operating on a secured system. Without the USB security dongle and proper credentials, a person cannot log into the network or access the software under its protection.

What are SDHC Cards

SDHC (Secure Digital High-Capacity) cards are flash memory cards with a minimum capacity of 4GB (gigabytes). SDHC cards provide removable memory for compatible digital devices including cameras, camcorders, PDAs, MP3 players and more. Secure Digital refers to a specific format within the flash card market. SDHC cards are designed for devices that are compatible with the SDHC 2.00 specification. Products designed exclusively to support previous SD specifications 1.0 and 1.1 will not be able to utilize SDHC cards.

The growing demand for high-capacity flash memory springs partially from the increasing use of high-definition video and high-resolution digital photography. SDHC cards meet the challenge of these demanding products not only by providing ample storage but also by introducing a new feature: classifications of data transfer speed (DTS). Consumers can get the best performance value out of their digital products by using flash memory cards that support the device's highest standards for data transfer speed. The SDHC specification 2.00 calls for cards to be classified according to the minimal sustained DTS as follows:

1. Class 2: minimum sustained DTS of 2MB/sec
2. Class 4: minimum sustained DTS of 4MB/sec
3. Class 6: minimum sustained DTS of 6MB/sec

SDHC cards are classified to guarantee a specific sustained DTS. This potentially saves consumers money, as flash cards are priced not only according to capacity, but also to speed. For example, if a product's maximum DTS is 2MB/sec, dishing out extra cash for Class 4 or Class 6 SDHC cards would be a waste of money. Conversely, devices that can utilize the 4MB/sec or 6MB/sec DTR will perform significantly better with Class 4 or Class 6 SDHC cards, respectively.

Secure Digital was forced to create a new specification for SDHC cards when the previous specification topped out at a capacity of 2GB. This occurred previously when SD cards hit the 512MB wall. The new 2.00 specification should last a bit longer, as it allows SDHC cards to reach a maximum capacity of 32GB. Secure Digital is so-named because of its ability to protect copyright content through digital rights management or DRM. Because of this, it is a favored flash memory format in the audiovisual industry. 

SDHC cards are about the size of a postage stamp. Insiders expect them to be available through several different manufacturers by summer 2006, and prices will vary. Before purchasing, be sure your device is compatible. There are several card formats available on the market, and devices are proprietary. If a device manual does not list SDHC cards, or state it is "SD specification 2.00 compatible," the device cannot utilize these cards.

What is a Wireless TV Router

A wireless TV router is a device that allows a television signal to be broadcast to other areas of the home without cables. This will allow viewing in a number of different ways, depending on the type of home equipment. For example, the wireless TV router could send a signal to a computer or a video projector for use on a large screen.

The technology behind wireless TV routers is still in the process of being fully developed. However, Apple has announced its intentions to manufacture a product known as iTV. This is essentially a wireless TV router that will allow users to download movies from a system, such as iTunes™ and then play those movies on a standard or high-definition television set. While this can be done now, it requires connecting a computer by wires to the TV set.

Another technology in development is known as WHDI, or wireless home digital interface. A number of companies are responsible for developing this technology. They include: Sony, AMIMON, Hitachi, Motorola, Samsung and Sharp. Together, these companies are setting a standard for a new type of wireless TV router that will cater specifically to high-definition applications.

The demand for a fully functional wireless TV router is growing. With TVs becoming flatter and lighter, the locations where they can be placed continues to expand. However, unsightly wires make some locations impractical, or unattractive, without a great deal of additional work, such as running wires behind walls.

Further, with more TVs in more rooms of the home, it may take a lot of extra cable to fully outfit each set. With a wireless TV router, the hardware setup would become as simple as plugging the router in and making sure each television was connected. However, before this happens, there are still some obstacles to overcome.

As with any new technology, standardization will be a big key in order to get such products on the market in an affordable and acceptable form. For those waiting for such technology, it should be encouraging that WHDI has so many industry leaders working on a product together. This helps with standardization.

Another obstacle will be existing televisions, which are not outfitted to receive wireless signals such as the kind that will be utilized by a wireless TV router. In order to take advantage of such technology, users will either have to replace television sets with sets that can receive those signals, or buy an adapter for existing televisions. So even after buying the wireless TV router, there is likely to be some additional expense.