Whiteboard
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This article is about physical whiteboards. For software-based whiteboards, see Whiteboarding.
A blank whiteboard
A whiteboard (also known as a markerboard, dry-erase board, dry-wipe board or a pen-board) is a name for any glossy surface, most commonly colored white, where non-permanent markings can be made. Whiteboards operate analogously to chalkboards in that they allow markings to temporarily adhere to the surface of the board. The popularity of whiteboards increased rapidly in the mid-1990s and they have become a fixture in many offices, meeting rooms, school classrooms, and other work environments.[1]
Instead of using chalk (as on chalkboards) to make the markings, a special marker pen containing removable ink is used (see non-permanent marker). Whiteboards are constructed with one of three materials; the cheaper melamine resin, polyester coated steel and more expensive models made from enameled steel. Steel whiteboards are magnetic, so one can use magnets to affix notes or a magnetic eraser to them. Enameled steel boards are more durable than painted steel and standard melamine boards. Melamine resin and painted steel will fade to a slight gray color over time, as ink of the dry markers enters into the pores of the material. Vitreous enamel is practically impermeable for dry marker ink and will remain white throughout the lifespan of the whiteboard. Enameled, coated steel and melamine all exhibit ghosting. Ghosting occurs as a result of the solvents (usually alcohol) in dry markers that effectively make the board cleaner where there has been writing. This remains visible after the ink is wiped off, but ghosting disappears after a short time.
The term whiteboard is also used metaphorically to refer to features of computer software applications that simulate whiteboards. Virtual whiteboards allow one or more people to write or draw images on a simulated canvas. This is a common feature of many virtual meeting, collaboration, and instant messaging applications. Today, the term Whiteboard is also used to refer to interactive whiteboards.
Contents
1 Whiteboard history
2 Advantages
3 Disadvantages
4 See also
5 References
[Whiteboard history
A combination whiteboard and bulletin board
Modern whiteboards evolved from chalkboards.
In the 1990s, concern over allergies and other potential health risks posed by chalk dust prompted the replacement of many blackboards with whiteboards. A whiteboard, otherwise known as a dry-erase board, uses special pens to make colored marks.
The first whiteboards were very expensive and the markers were toxic. Other whiteboards were made of a melamine or enameled hardboard surface. It was the "perfect" solution to the chalkboard, except that it ghosted in a short time and was not easy to keep clean. The first enamel-on-steel write-on/ wipe-off magnetic whiteboard is believed to have been created by Magiboards in the UK. Inventor Michael Boone of the United States, was the first to successfully mass-market the "Boone Board" brand dry-erase board.
Over the last 10 years, the enamel-on-steel magnetic whiteboard has gone through some improvements, such as cost reduction and a reduction in glare caused by the glossy surface.
Advantages
Whiteboard ink markings are less susceptible to external factors, such as water, because the ink adheres in a different manner than chalk does to chalkboards. As well, using markers does not generate the dust that comes from using and erasing chalk, allowing their use in areas containing dust-sensitive equipment. Some who are allergic to chalk or are asthmatic use whiteboards as an alternative.
A whiteboard can be used as the projecting medium for an overhead or video projector. This allows the person giving the presentation to fill in blanks, edit, underline and make comments by writing directly onto the whiteboard, which in turn shows through the projected image.
A dry erase marker is easier to hold and write with. This can benefit persons with limited mobility in their hands, such as those affected by diseases such as arthritis or systemic lupus erythematosus. In addition, marking on a whiteboard takes less time, effort, and pressure than marking on a chalkboard.
Whiteboards save paper.
When compared to a chalkboard a whiteboard can have significantly more colors because markers have a greater range of color than chalk.
Disadvantages
Whiteboards are slightly more expensive than blackboards. In addition, only special whiteboard markers are suitable for use on whiteboards. Using other markers that resemble whiteboard markers but contain the wrong kind of ink creates markings that are hard or impossible to remove. However, some techniques have been developed, which include filling over them using a marker with the right type of removable ink and then erasing the ink; wiping the marks with acetone or alcohol; or by using board cleaning sprays or prepackaged wipes commercially available from the whiteboard manufacturers.
The white background can cause contrast problems for people with vision impairment. Additionally, whiteboards cause some problems for those who write left-handed as many write with their hand curved around the pen, therefore causing their hand to drag across the board, smearing the marker strokes previously made. Similarly, right-handed people have this problem with right-to-left languages, such as Arabic. This limitation is also present with a chalkboard.
Another disadvantage of the whiteboard is concerned with the issues of the actual usable ink remaining in a dry-erase marker. Since the markers are often tightly sealed in plastic, it is not possible to accurately gauge the amount of ink available. In contrast, blackboards, using chalk do not have this problem as the chalk visibly reduces with use.
2009年2月6日星期五
Talking Pen
The New Spirit
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The New Spirit is a World War II propaganda animated short film created by Walt Disney Studios in 1942 and sponsored by the United States Department of the Treasury. In 1943 the film was nominated for the Academy Award for Best Documentary Feature.
Plot summary
The film begins with Donald Duck, flush with the contemporary patriotic spirit present with the United States' full entry into the war, dancing to a patriotic song. Afterward, a radio announcer tells about the new patriotic spirit and asks Donald if he was willing to do his part. Donald feverently asserts his loyalty and begs to know how best to do it.
However, Donald's enthusiasm instantly fades when the radio announcer advises he pay his income tax promptly. However, the announcer changes the duck's mind by stressing the need for the funds for the war effort with the slogan, "Taxes to beat the Axis". Sufficiently motivated, the announcer guides Donald, with the help of a talking pen, inkwell and blotter, on how to properly fill out his simplified tax form. With the bureaucratic task completed, the announcer urges Donald to mail his payment to the Federal government at once and Donald enthuastically and literally races across the nation to Washington DC to deliver it in person.
The film concludes with a montage of images to illustrate to the audience the wartime necessities the money is needed for such as munitions and combat vehicles to defeat the Axis powers. With a final images framed in a sky lined with red, white and blue, the announcer repeats The Four Freedoms and reminds the audience that taxes are essential for victory.
Reportedly, when Secretary of the Treasury Henry Morgenthau, Jr. learned that Walt Disney proposed using Donald Duck as the feature character of the film, he insisted that a generic "Mr. Taxpayer" be used instead. However, Disney persuaded Morgenthau and President Franklin D. Roosevelt that the film would be more effective with a popular and familiar character. The popular reaction of the film led to a dramatic increase of prompt taxation payments by the public. This prompted a sequel, The Spirit of '43 which reuses the original film's conclude montage in addition to original footage.
Staple Remover
Staple remover
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This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (September 2007)
Staple remover (opposing wedge type)
Stapler with integrated staple remover
A staple remover (also known as a staple decleater, staple puller, destapler, butterfly or crimper) is a device that allows for the quick removal of a staple from a material without causing damage. Although a simple metal wedge can be used, this method tends to tear fragile papers. For light gauge staples, many people instead use a device consisting of two opposing wedges on a pivot. For convenience, this device has a spring that returns it to the open position after use.
Some staplers, mainly small ones that are about 1.5 inches (3.8 cm) long contain an integrated staple remover. This is basically a piece of metal that is slid under each "curled" side of the staple and turned to loosen the staple.
Staple removers are known as decleaters in many former British colonies, such as Barbados.
Contents
1 Use
2 Design
3 Components
3.1 Blades
3.2 Torsion springs
3.3 Plastic grips
3.4 Pin axle
4 History
5 See also
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (September 2007)
Staple remover (opposing wedge type)
Stapler with integrated staple remover
A staple remover (also known as a staple decleater, staple puller, destapler, butterfly or crimper) is a device that allows for the quick removal of a staple from a material without causing damage. Although a simple metal wedge can be used, this method tends to tear fragile papers. For light gauge staples, many people instead use a device consisting of two opposing wedges on a pivot. For convenience, this device has a spring that returns it to the open position after use.
Some staplers, mainly small ones that are about 1.5 inches (3.8 cm) long contain an integrated staple remover. This is basically a piece of metal that is slid under each "curled" side of the staple and turned to loosen the staple.
Staple removers are known as decleaters in many former British colonies, such as Barbados.
Contents
1 Use
2 Design
3 Components
3.1 Blades
3.2 Torsion springs
3.3 Plastic grips
3.4 Pin axle
4 History
5 See also
Use
Proper use of the opposing wedge staple remover should also be noted. Staples should be removed via the flat, top side of the staple, not the back "curled" side of the staple. This can however often result in ripping of some paper, so some prefer to loosen the staple via the "curled" side before proceeding to the front flat side for easy removal.
Design
A standard staple remover is constructed of just five distinct components:
two plastic grips
torsion spring
two sets of metal swinging wedges (i.e., the blades)
metal pin axle
two smaller pins
The design is focused on functionality and robustness with no unnecessary decoration (unless one includes the ergonomics of the handle) and minimised number of parts to lower costs and production time. The device works with a pincer action to unfold and pull out a staple in one motion.
Components
Blades
The two pivoting blades interlock each other. They are made of chrome-plated steel, which is harder than the thin ductile wire of the staple and strong enough to withstand the force required to remove it. The chrome plating provides a mild rust-resistance suitable for use in an office environment away from any liquids. Though the blade is made from what was originally sheet metal, the right angles and clean edges mean that a punch and die method of production would not be suitable. Therefore, the piece of sheet metal is cut using the process of blanking in a mechanical press, then bent in a press brake. This is a highly automated method which allows for a production rate of up to 1,500 units per minute.
Torsion springs
The torsion spring in this staple remover is a standardised component that appears in many other products, such as clothes pegs. It has two loops. The spring is made of chrome-plated steel, which is used because there is a point of minimum stress where continued use (opening and closing the staple remover) will not cause failure through fatigue. They are mass produced by a spring winding machine which cold winds wire around an arbour before heat treating to make it harder. The spring is then chrome plated. The machinery to do this is large, expensive, but has a high production rate. That is why the springs are usually bought off-the-shelf from a tier 1 supplier rather than produced in house.
Plastic grips
The plastic grips are in fact unnecessary and the device could still be operated without them. They provide enhanced ergonomics so the user does not have to press their fingers against sheet metal. Injection moulding of thermoplastics are normally used through the use of an automated injection moulding machine, which shoots liquid plastic into a mould where it is left to set. Such processing is commonplace, not very labour intensive, cheap, and capable of producing high quantities. Plastic is used as it is the easiest, but also the cheapest and most readily available material that can be formed into such fluid shapes.
Pin axle
The pin axle provides a cylindrical bar from which the blades can rotate. It is made of stainless steel, which will not rust in areas that have been worn by contact with other metals. The process to create such a pin axle is quite intensive and hence it is bought off-the-shelf from a supplier. They are made by a specialised machine which cuts thick wire into a suitable length and then die punches the head of the pin. The supplier normally runs specialised machinery that is capable of producing large amounts of products at a high rate for a low cost.
History
The form of destapler described above was invented by William G. Pankonin of Chicago, Illinois. A patent application for the same was filed on 12 December 1932, granted on 3 March 1936 and published on 3 April 1936 as patent document US 2,033,050.
A modified version, also capable of removing broken staples, was patented by Joseph A. Foitle of Overland Park, Kansas, but does not see widespread use, despite overcoming several disadvantages of the former device by a simple, yet novel and inventive, modification. The patent for the latter invention was filed on 28 May 1969 and was granted on 28 December 1971, published as US 3,630,486 A. An excerpt from the patent application reads as follows:
"... A device for removing broken portions of wire staples ... comprising a pair of overlying planar arms pivoted together on an axis normal thereto, said arms having cooperating notches ... whereby relative pivotal motions ... may be engaged over the projecting portion of a broken staple..."
The pin axle provides a cylindrical bar from which the blades can rotate. It is made of stainless steel, which will not rust in areas that have been worn by contact with other metals. The process to create such a pin axle is quite intensive and hence it is bought off-the-shelf from a supplier. They are made by a specialised machine which cuts thick wire into a suitable length and then die punches the head of the pin. The supplier normally runs specialised machinery that is capable of producing large amounts of products at a high rate for a low cost.
History
The form of destapler described above was invented by William G. Pankonin of Chicago, Illinois. A patent application for the same was filed on 12 December 1932, granted on 3 March 1936 and published on 3 April 1936 as patent document US 2,033,050.
A modified version, also capable of removing broken staples, was patented by Joseph A. Foitle of Overland Park, Kansas, but does not see widespread use, despite overcoming several disadvantages of the former device by a simple, yet novel and inventive, modification. The patent for the latter invention was filed on 28 May 1969 and was granted on 28 December 1971, published as US 3,630,486 A. An excerpt from the patent application reads as follows:
"... A device for removing broken portions of wire staples ... comprising a pair of overlying planar arms pivoted together on an axis normal thereto, said arms having cooperating notches ... whereby relative pivotal motions ... may be engaged over the projecting portion of a broken staple..."
Table Pen
General description
A standard table tennis table, together with a racket and ball.
The sport is played with two or four players hitting a ball with rackets back and forth to each other on a table, in a manner similar to tennis. The rules are slightly different, but the concept is very similar. In singles play, the serve is not required to cross from the server's right-hand court to the receiver's right-hand court (or left to left) as it is in tennis. However, serving across is required in doubles play. Ball spin, speed, placement, strategy and tactics play an important part in competitive table tennis matches. The speed of the ball can vary from slow serves with much spin to smashes that travel as fast as 112.5 kilometers per hour (70 mph).
The game is played on a 274 cm × 152.5 cm × 76 cm high (9 ft × 5 ft × 30 inches high) playing surface. The International Table Tennis Federation requires an area not less than 14 m long, 7 m wide and 5 m high for competitions. No limitations in size or shape are specified.
Modern rackets usually have a thin layer of rubber covering the racket's striking surface. The rubber may have dimples pointing outwards or inwards, as well as a thin layer of sponge between the plywood center and the rubber surface. Since spin plays a large role in the modern sport of table tennis, the composition of the rubber and the combination of sponge and rubber is designed to maximize the amount of spin and speed a player can impart onto the ball. Other technological improvements include the use of carbon or other synthetic layers as part of the blade to increase the size of the sweet spot or the stiffness of the blade.
The ball used in table tennis has a diameter of 40 mm (formerly 38 mm), is made of celluloid, and is hollow. A three star rating on a ball usually implies a top quality ball, in relation to its bounce, roundness and their respective consistency between balls of the same make and type.
The winner is the first to score 11 points or more while being ahead by 2 points or more. Players alternate serves every two points. At 10-10 (or deuce) the players alternate with every serve; the winner is then the first person to gain a clear two points advantage over his opponent. The 11 point game is an International Table Tennis Federation (ITTF) change which occurred in 2001. Previously, the first player to gain 21 points (except in case of a deuce, handled as described above) won the game. All games played at national level and at international tournaments (ITTF) are now played to 11 points in either a best of five (5) games (preliminaries) or best of seven (7) games format (championship matches).
History
Table tennis depicted on a 1987 postage stamp from the GDR
The game has its origins in England as an after-dinner amusement for upper-class Victorians in the 1880s. Mimicking the game of tennis in an indoor environment, everyday objects were originally enlisted to act as the equipment. A line of books would be the net, a rounded top of a champagne cork or knot of string as the ball, and a cigar box lid as the racket.
Table tennis evolved into the modern game in Europe, the United States and Japan. The popularity of the game led game manufacturers to sell the equipment commercially. Early rackets were often pieces of parchment stretched upon a frame, and the sound generated in play gave the game its first nicknames of "whiff-whaff" and "Ping-pong." A number of sources indicate that the game was first brought to the attention of Hamley's of Regent Street under the name "Gossima". The name "ping-pong" was in wide use before English manufacturer J. Jaques & Son Ltd trademarked it in 1901. The name "Ping-Pong" then came to be used for the game played by the rather expensive Jaques equipment, with other manufacturers calling theirs table tennis. A similar situation came to exist in the United States where Jaques sold the rights to the "Ping-Pong" name to Parker Brothers.
The next major innovation was by James Gibb,an English enthusiast of table tennis, who discovered novelty celluloid balls on a trip to the U.S. in 1901 and found them to be ideal for the game. This was followed by E.C. Goode who in 1901 invented the modern version of the racket by fixing a sheet of pimpled, or stippled, rubber to the wooden blade. Table tennis was growing in popularity by 1901 when table tennis tournaments were being organized, books on table tennis were being written, and an unofficial world championship was held in 1902. During the early 20th century the game was banned in Russia due to a belief that was held by the rulers at the time that playing the game had an adverse effect on players' eyesight. In 1921, the Table Tennis Association was founded in England, and the International Table Tennis Federation followed in 1926. London hosted the first official world championship in 1927. Table tennis was introduced as an Olympic sport at the Olympics in 1988.
In the 1950s rackets that used a rubber sheet combined with an underlaying sponge layer changed the game dramatically, introducing greater spin and speed. These were introduced to England by the sports goods manufacturers S.W. Hancock Ltd. The use of speed glue increased the spin and speed even further, resulting in changes to the equipment to "slow the game down."
Toward the end of 2000, the ITTF instituted several rules changes aimed at making table tennis more viable as a televised spectator sport. First, the older 38 mm (1.5 inch) balls were officially replaced by 40 mm balls. This increased the ball's air resistance and effectively slowed down the game. By that time, players had begun increasing the thickness of the fast sponge layer on their rackets, which made the game excessively fast, and difficult to watch on television. Secondly, the ITTF changed from a 21 to an 11 point scoring system. This was intended to make games more fast-paced and exciting. The ITTF also changed the rules on service to prevent a player from hiding the ball during service, in order to increase the average length of rallies and to reduce the server's advantage. Variants of the sport have emerged. "Large-ball" table tennis uses a 44 mm ball which slows down the game significantly. This has seen some acceptance by players who have a hard time with the extreme spins and speeds of the 40 mm game. The ball's mass is 2.47 grams.
There is a move towards reviving the table tennis game that existed prior to the introduction of sponge rubber. Classic table tennis or "Hardbat" table tennis players reject the speed and spin of reversed sponge rubber, preferring the 1940-60s play style, with no-sponge, short pimpled rubber equipments, when defense is less difficult by decreasing the speed and eliminating any meaningful magnus effect of spin. Because hardbat killer shots are almost impossible to hit against a skilled player, hardbat matches focus on the strategic side of table tennis, requiring skillful maneuvering of the opponent before an attack can be successful.
A standard table tennis table, together with a racket and ball.
The sport is played with two or four players hitting a ball with rackets back and forth to each other on a table, in a manner similar to tennis. The rules are slightly different, but the concept is very similar. In singles play, the serve is not required to cross from the server's right-hand court to the receiver's right-hand court (or left to left) as it is in tennis. However, serving across is required in doubles play. Ball spin, speed, placement, strategy and tactics play an important part in competitive table tennis matches. The speed of the ball can vary from slow serves with much spin to smashes that travel as fast as 112.5 kilometers per hour (70 mph).
The game is played on a 274 cm × 152.5 cm × 76 cm high (9 ft × 5 ft × 30 inches high) playing surface. The International Table Tennis Federation requires an area not less than 14 m long, 7 m wide and 5 m high for competitions. No limitations in size or shape are specified.
Modern rackets usually have a thin layer of rubber covering the racket's striking surface. The rubber may have dimples pointing outwards or inwards, as well as a thin layer of sponge between the plywood center and the rubber surface. Since spin plays a large role in the modern sport of table tennis, the composition of the rubber and the combination of sponge and rubber is designed to maximize the amount of spin and speed a player can impart onto the ball. Other technological improvements include the use of carbon or other synthetic layers as part of the blade to increase the size of the sweet spot or the stiffness of the blade.
The ball used in table tennis has a diameter of 40 mm (formerly 38 mm), is made of celluloid, and is hollow. A three star rating on a ball usually implies a top quality ball, in relation to its bounce, roundness and their respective consistency between balls of the same make and type.
The winner is the first to score 11 points or more while being ahead by 2 points or more. Players alternate serves every two points. At 10-10 (or deuce) the players alternate with every serve; the winner is then the first person to gain a clear two points advantage over his opponent. The 11 point game is an International Table Tennis Federation (ITTF) change which occurred in 2001. Previously, the first player to gain 21 points (except in case of a deuce, handled as described above) won the game. All games played at national level and at international tournaments (ITTF) are now played to 11 points in either a best of five (5) games (preliminaries) or best of seven (7) games format (championship matches).
History
Table tennis depicted on a 1987 postage stamp from the GDR
The game has its origins in England as an after-dinner amusement for upper-class Victorians in the 1880s. Mimicking the game of tennis in an indoor environment, everyday objects were originally enlisted to act as the equipment. A line of books would be the net, a rounded top of a champagne cork or knot of string as the ball, and a cigar box lid as the racket.
Table tennis evolved into the modern game in Europe, the United States and Japan. The popularity of the game led game manufacturers to sell the equipment commercially. Early rackets were often pieces of parchment stretched upon a frame, and the sound generated in play gave the game its first nicknames of "whiff-whaff" and "Ping-pong." A number of sources indicate that the game was first brought to the attention of Hamley's of Regent Street under the name "Gossima". The name "ping-pong" was in wide use before English manufacturer J. Jaques & Son Ltd trademarked it in 1901. The name "Ping-Pong" then came to be used for the game played by the rather expensive Jaques equipment, with other manufacturers calling theirs table tennis. A similar situation came to exist in the United States where Jaques sold the rights to the "Ping-Pong" name to Parker Brothers.
The next major innovation was by James Gibb,an English enthusiast of table tennis, who discovered novelty celluloid balls on a trip to the U.S. in 1901 and found them to be ideal for the game. This was followed by E.C. Goode who in 1901 invented the modern version of the racket by fixing a sheet of pimpled, or stippled, rubber to the wooden blade. Table tennis was growing in popularity by 1901 when table tennis tournaments were being organized, books on table tennis were being written, and an unofficial world championship was held in 1902. During the early 20th century the game was banned in Russia due to a belief that was held by the rulers at the time that playing the game had an adverse effect on players' eyesight. In 1921, the Table Tennis Association was founded in England, and the International Table Tennis Federation followed in 1926. London hosted the first official world championship in 1927. Table tennis was introduced as an Olympic sport at the Olympics in 1988.
In the 1950s rackets that used a rubber sheet combined with an underlaying sponge layer changed the game dramatically, introducing greater spin and speed. These were introduced to England by the sports goods manufacturers S.W. Hancock Ltd. The use of speed glue increased the spin and speed even further, resulting in changes to the equipment to "slow the game down."
Toward the end of 2000, the ITTF instituted several rules changes aimed at making table tennis more viable as a televised spectator sport. First, the older 38 mm (1.5 inch) balls were officially replaced by 40 mm balls. This increased the ball's air resistance and effectively slowed down the game. By that time, players had begun increasing the thickness of the fast sponge layer on their rackets, which made the game excessively fast, and difficult to watch on television. Secondly, the ITTF changed from a 21 to an 11 point scoring system. This was intended to make games more fast-paced and exciting. The ITTF also changed the rules on service to prevent a player from hiding the ball during service, in order to increase the average length of rallies and to reduce the server's advantage. Variants of the sport have emerged. "Large-ball" table tennis uses a 44 mm ball which slows down the game significantly. This has seen some acceptance by players who have a hard time with the extreme spins and speeds of the 40 mm game. The ball's mass is 2.47 grams.
There is a move towards reviving the table tennis game that existed prior to the introduction of sponge rubber. Classic table tennis or "Hardbat" table tennis players reject the speed and spin of reversed sponge rubber, preferring the 1940-60s play style, with no-sponge, short pimpled rubber equipments, when defense is less difficult by decreasing the speed and eliminating any meaningful magnus effect of spin. Because hardbat killer shots are almost impossible to hit against a skilled player, hardbat matches focus on the strategic side of table tennis, requiring skillful maneuvering of the opponent before an attack can be successful.
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