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The Golden Gate Bridge

The Golden Gate Bridge in San Francisco is a marvelous feat of Engineering. Located on the Golden Gate Strait in San Francisco Bay, the idea of a bridge linking the two sides of the bay was first discussed in 1872. It wasn’t until the 1930`s that an Engineer named Joseph B. Strauss submitted the final plans for the bridge to the District Board of Directors and construction began.

The Art Deco styling that the bridge is famous for was the idea of the husband and wife partnership, Irving and Gertrude Morrow, with their subtle ideas and eye for good taste; they created the easy on the eye bridge span. With opposition from the US Navy, Morrow and his wife chose a unique colour for the bridge known as ‘International Orange’ and this has become famous all over the world. As Chief Engineer Strauss was very safety conscious he, with the help of Edward Bullard, a local manufacturer of safety equipment, introduced new, ground breaking safety procedures which are still followed on a high percentage of construction sites to this very day. The death rate for men working on the bridge for the time of construction was second to none showing how important safety precautions where and still are.

Key Dates

1872 . Earliest discussion of building a bridge to span the Golden Gate Strait.

May 25, 1923. The state legislature passes the Golden Gate Bridge and Highway District Act of California into law.

December 4, 1928. Golden Gate Bridge and Highway District is incorporated as the entity to design, construct, and finance the Golden Gate Bridge.

August 27, 1930. Joseph Strauss submits his final plans for the bridge to the District Board of Directors.

November 4, 1930. Voters within the 6 counties of the District approve the $35 million bond issue to finance construction of the bridge.

January 5, 1933. Construction of the GGB begins.

May 27, 1937. opens to pedestrian traffic

May 28, 1937. opens to vehicular traffic at twelve noon. The bridge opened ahead of schedule and under budget.

July 1, 1971. Remaining original bonds issued for construction of the bridge are retired. $35 million and almost $39 million in interest were financed entirely from bridge tolls.

February 22, 1985. The one-billionth car crosses the bridge.

August 15, 1985. Construction completed on the replacement of the original roadway with modern orthotropic steel plate deck.

May 27, 1987. celebrates its 50th Anniversary.

September 2, 1998. United States Postal Service unveils Golden Gate Bridge commemorative stamp.

March 1999. The Golden Gate Bridge awarded number two position in Top 10 Construction Achievements of the 20th Century by CONEXPO-CON/AGG SECOND ONLY TO Chunnel Tunnel (Channel Tunnel).

Bridge Rectifiers – Ideal for Converting Alternating Current Input Into a Direct Current Output

Bridge is an arrangement of four diodes in a bridge circuit configuration that provides the same polarity for either polarity of input. The most common use for this application for conversion of an alternating current input into a direct current output known as a bridge rectifier. A rectifier provides full-wave rectification from a two-wire AC input, resulting in lower cost and weight as compared to a rectifier with a 3-wire input from a transformer with a center-tapped secondary winding. A rectifier in itself is simply an electrical device that converts alternating current (AC) to direct current (DC) in a process called rectification. AC can flow in reverse direction while DC only flows in one direction. Rectify can come in many forms, which include but are not limited to vacuum tube diodes, mercury-arc valves, copper and selenium oxide rectifiers, semiconductor diodes, silicon-controlled rectifiers, in addition to other silicon-based semiconductor switches.

The main uses of bridge rectifier are in DC power supplies and high-voltage direct current power transmission systems. Initially, vacuum tube thermionic diodes and copper oxide or selenium-based metal rectifier stacks were used before the introduction of silicon semiconductor rectifiers. Once silicon semiconductor rectifier were introduced, other types of rectifier immediately became obsolete, with the exception of enthusiasts for vacuum tube radio equipment. There have been many types of different rectification technologies, beginning with the electromechanical rectifier in 1905 and progressing to the synchronous rectifier, vibrating rectifier, motor-generator set, electrolytic rectifier, plasma type, and solid state, respectively. The various specifications to consider when analyzing current day bridge rectifiers are the peak reverse voltage, maximum reverse voltage, forward continuous current, max surge current, forward voltage drop, maximum reverse leakage current, power dissipation, and maximum operating temperature. It also comes in varying dimensions of length, width, height as well as mounting style and packaging.

The most common sizes for maximum average rectified current are 1 A, 1.5 A, 4 A, 25 A, and 35 A but can also be found as high as 1000 A. Forward voltage for bridge rectifier is most commonly 1.1 V or 1 V, although it can range from 450 mV to 1.1 kV. The top manufacturers of bridge rectifiers are Bourn, Central Semiconductor, Com chip Technology, Diodes Inc, Fairchild Semiconductor, GeneSiC Semiconductor, Infineon, IXYS, Micro Commercial Components, NJR, ON Semiconductor, Rectron, Shindengen, ST-Microelectronics, Taiwan Semiconductor, Texas Instruments, and Vishay.

You can browse on web for leading distributor of all types of Bridge Rectifier components from a comprehensive list of manufacturers. On this sites where you can get tier 1 pricing from manufacturers which pass selected savings to you.

Important Industrial Metal Alloys and Their Uses

Metals in the form in which they are received from the nature are not useful for many types of applications. The discovery of alloys is considered no less than a revolution that influenced a number of industrial applications in a big way. Today, iron and aluminum alloys and those of a number of other metals like tin, cobalt, nickel; gold and silver form the base of many important industries.

The advantage of alloys is that they exhibit properties of all the constituting metals. For example, these alloys exhibit better thermal properties, tensile strength and wider range of melting points. Here are some sections about the most popular alloys, along with their industrial uses and applications.

Copper Alloys

Used for applications with low friction requirement, brass is one of the popular metal alloys made by mixing copper with zinc. Valves, locks, bearings and gears are some examples of these applications. Moreover, brass is known for its recyclable nature. Another common copper alloy is bronze which contains tin as another constituent metal. Apart from being a popular material for sculptures, bronze is also widely used for making window weather-stripping and automobile transmission bearings.

Aluminum Alloys

Needless to say, the aluminum alloys are the most popular materials that have great importance in many industrial uses. Consisting of aluminum, nickel and cobalt, alnico is one of these alloys and is used in electric motors, cow magnets, sensors and microphones. Duralumin is made of aluminum, copper, manganese and magnesium and is an extremely popular alloy for aircraft structures, truck wheels, auto body panel sheets, forgings, pistons and many other applications. Among other aluminum alloys is magnalium which is also used in many automobile and aircraft parts.

Iron Alloys

Iron needs no introduction for being a popular choice for many metal alloys like steel and stainless steel. Steel is extremely admirable for its high rust resistance, tensile strength and welding ability. The alloy is a useful material for the construction of railways, roads, bridges and skyscrapers. Stainless steel is a famous variety of steel and is used in making surgical instruments, industrial equipments, bridges and aircraft and automobile body parts.

Iron alloys with carbon as an important constituent are extensively accepted. Wrought iron, for example, has applications like manufacturing of gates and furniture items like racks, tables, desks and chairs. Pig iron is used in blast furnaces and different varieties of cast iron are used in machine tools, gears crankshafts and cooking accessories like pans.

Other Metal Alloys

Tin is also used as the main constituent for many alloys like pewter and solder. While pewter is mainly used as a decorative material, solder is a widely used material for joining (called soldering) metals for many important industrial applications. Sterling silver is a well-known alloy of silver. It is useful not only as a jewelry material, but also for making medical and musical instruments.

Nichrome, an alloy of nickel, is used in explosive industry for electric ignition systems. Resistance wires made of this alloy too are popular.

Different types of industry owners can obtain genuine and pure forms of metal alloys from various parts of the world. Comparing the varieties using online catalogues can help in this direction.