1.
Radio masts and towers
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Radio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two types, guyed and self supporting structures. They are among the tallest man-made structures, masts are often named after the broadcasting organizations that originally built them or currently use them. In the case of a mast radiator or radiating tower, the whole mast or tower is itself the transmitting antenna, the terms mast and tower are often used interchangeably. However, in engineering terms, a tower is a self-supporting or cantilevered structure. Broadcast engineers in the UK use the same terminology, in US broadcast engineering, a tower is an antenna structure attached to the ground, whereas a mast is a vertical antenna support mounted on some other structure. Masts tend to be cheaper to build but require an extended area surrounding them to accommodate the guy wires, Towers are more commonly used in cities where land is in short supply. There are a few designs that are partly free-standing and partly guyed, called additionally guyed towers. For example, The Gerbrandy tower consists of a tower with a guyed mast on top. The few remaining Blaw-Knox towers do the opposite, they have a lower section surmounted by a freestanding part. Until August 8,1991, the Warsaw radio mast was the worlds tallest supported structure on land, there are over 50 radio structures in the United States that are 600 m or taller. The steel lattice is the most widespread form of construction and it provides great strength, low weight and wind resistance, and economy in the use of materials. Lattices of triangular cross-section are most common, and square lattices are also widely used, guyed masts are often used, the supporting guy lines carry lateral forces such as wind loads, allowing the mast to be very narrow and simply constructed. When built as a tower, the structure may be parallel-sided or taper over part or all of its height, when constructed of several sections which taper exponentially with height, in the manner of the Eiffel Tower, the tower is said to be an Eiffelized one. The Crystal Palace tower in London is an example, guyed masts are sometimes also constructed out of steel tubes. This construction type has the advantage that cables and other components can be protected from weather inside the tube and these masts are mainly used for FM-/TV-broadcasting, but sometimes also as mast radiator. The big mast of Mühlacker transmitting station is an example of this. A disadvantage of this mast type is that it is more affected by winds than masts with open bodies
2.
San Francisco
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San Francisco, officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. It is the birthplace of the United Nations, the California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. San Francisco became a consolidated city-county in 1856, after three-quarters of the city was destroyed by the 1906 earthquake and fire, San Francisco was quickly rebuilt, hosting the Panama-Pacific International Exposition nine years later. In World War II, San Francisco was a port of embarkation for service members shipping out to the Pacific Theater. Politically, the city votes strongly along liberal Democratic Party lines, San Francisco is also the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. Dolby, Airbnb, Weebly, Pacific Gas and Electric Company, Yelp, Pinterest, Twitter, Uber, Lyft, Mozilla, Wikimedia Foundation, as of 2016, San Francisco is ranked high on world liveability rankings. The earliest archaeological evidence of habitation of the territory of the city of San Francisco dates to 3000 BC. Upon independence from Spain in 1821, the became part of Mexico. Under Mexican rule, the system gradually ended, and its lands became privatized. In 1835, Englishman William Richardson erected the first independent homestead, together with Alcalde Francisco de Haro, he laid out a street plan for the expanded settlement, and the town, named Yerba Buena, began to attract American settlers. Commodore John D. Sloat claimed California for the United States on July 7,1846, during the Mexican–American War, montgomery arrived to claim Yerba Buena two days later. Yerba Buena was renamed San Francisco on January 30 of the next year, despite its attractive location as a port and naval base, San Francisco was still a small settlement with inhospitable geography. The California Gold Rush brought a flood of treasure seekers, with their sourdough bread in tow, prospectors accumulated in San Francisco over rival Benicia, raising the population from 1,000 in 1848 to 25,000 by December 1849. The promise of fabulous riches was so strong that crews on arriving vessels deserted and rushed off to the gold fields, leaving behind a forest of masts in San Francisco harbor. Some of these approximately 500 abandoned ships were used at times as storeships, saloons and hotels, many were left to rot, by 1851 the harbor was extended out into the bay by wharves while buildings were erected on piles among the ships. By 1870 Yerba Buena Cove had been filled to create new land, buried ships are occasionally exposed when foundations are dug for new buildings. California was quickly granted statehood in 1850 and the U. S. military built Fort Point at the Golden Gate, silver discoveries, including the Comstock Lode in Nevada in 1859, further drove rapid population growth. With hordes of fortune seekers streaming through the city, lawlessness was common, and the Barbary Coast section of town gained notoriety as a haven for criminals, prostitution, entrepreneurs sought to capitalize on the wealth generated by the Gold Rush
3.
California
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California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California also has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire then claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence. The western portion of Alta California then was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, government, real estate services, technology, and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups also were diverse in their organization with bands, tribes, villages. Trade, intermarriage and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years later English explorer Francis Drake also explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
4.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
5.
Truss
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In engineering, a truss is a structure that consists of two-force members only, where the members are organized so that the assemblage as a whole behaves as a single object. A two-force member is a component where force is applied to only two points. In this typical context, external forces and reactions to those forces are considered to act only at the nodes and result in forces in the members that are either tensile or compressive. For straight members, moments are explicitly excluded because, and only because, all the joints in a truss are treated as revolutes, as is necessary for the links to be two-force members. A planar truss is one all members and nodes lie within a two dimensional plane, while a space truss has members and nodes that extend into three dimensions. The top beams in a truss are called top chords and are typically in compression, the beams are called bottom chords. The interior beams are called webs, and the areas inside the webs are called panels, Truss derives from the Old French word trousse, from around 1200, which means collection of things bound together. The term truss has often used to describe any assembly of members such as a cruck frame or a couple of rafters. One engineering definition is, A truss is a single plane framework of individual structural member connected at their ends of forms a series of triangle to span a large distance, a truss consists of typically straight members connected at joints, traditionally termed panel points. Trusses are typically composed of triangles because of the stability of that shape. A triangle is the simplest geometric figure that will not change shape when the lengths of the sides are fixed, in comparison, both the angles and the lengths of a four-sided figure must be fixed for it to retain its shape. The joint at which a truss is designed to be supported is commonly referred to as the Munter Point, the simplest form of a truss is one single triangle. This type of truss is seen in a roof consisting of rafters and a ceiling joist. Because of the stability of this shape and the methods of used to calculate the forces within it. The traditional diamond-shape bicycle frame, which utilizes two conjoined triangles, is an example of a simple truss, a planar truss lies in a single plane. Planar trusses are used in parallel to form roofs and bridges. The depth of a truss, or the height between the upper and lower chords, is what makes it an efficient structural form, a solid girder or beam of equal strength would have substantial weight and material cost as compared to a truss. For a given span, a deeper truss will require less material in the chords, an optimum depth of the truss will maximize the efficiency
6.
Twin Peaks (San Francisco)
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The Twin Peaks are two prominent hills with an elevation of about 925 feet located near the geographic center of San Francisco, California. Only 928 foot Mount Davidson is higher within the city, the North and South Twin Peaks, also known as Eureka and Noe respectively, are about 200 m apart, Twin Peaks Boulevard runs a figure eight around them. The peaks form a divide for the coastal fog pushed in from the Pacific Ocean. Their west-facing slopes often get fog and strong winds, while the east-facing slopes receive more sun, elevation at each summit is just over 900 feet. Thin, sandy soil is commonplace on Twin Peaks, making them susceptible to erosion, before the arrival of the Europeans, the native Ohlone people may have used Twin Peaks as a lookout or hunting ground. The ecological diversity of Twin Peaks provided medicinal or ceremonial plants, grains, when the Spanish conquistadors and settlers arrived at the beginning of the 18th century, they called the area Los Pechos de la Chola or Breasts of the Indian Maiden and devoted the area to ranching. When San Francisco passed under American control during the 19th century, christmas Tree Point lies some 70 ft below the North Peak and offers vistas of San Francisco and San Francisco Bay. To the north is one of the many reservoirs. It is owned by the San Francisco Fire Department, and supplies water to the Fire Departments independent HPFS water system for fighting fires, established after the 1906 earthquake, the top of Twin Peaks is undeveloped. It is part of the 31 acres Twin Peaks Natural Area, managed and owned by the San Francisco Recreation and these preserved areas are home to many natural resources and wildlife. As part of the Mission blue butterfly habitat conservation, Twin Peaks is one of the few remaining habitats for endangered species. Many bird species, insects and vegetation thrive in these areas, the Muni Metro Twin Peaks Tunnel runs beneath Twin Peaks, linking Downtown San Francisco with West Portal and the southwestern part of the city. There is no public transportation all the way to the top of the Peaks, the San Francisco Police Department Academy is at the base of the peaks. The name Twin Peaks is also applied to the surrounding neighborhood, 49-Mile Scenic Drive List of San Francisco, California Hills Twin Peaks. Treasures in the curves and swells of Twin Peaks
7.
Mount Sutro
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Mount Sutro is a hill in central San Francisco, California. It was originally named Mount Parnassus, the low mountain is 909 feet in elevation. Mount Sutro is one of the many named hills within San Francisco, most of Mount Sutro is owned by the University of California, San Francisco. A 61-acre parcel, including the summit, is protected as the Mount Sutro Open Space Reserve by UCSF, Sutro Tower, a large television and radio broadcasting tower for the San Francisco Bay Area and very visible City landmark is not on Mount Sutro. It stands on a hill to the south between it and Twin Peaks. Mount Sutro has been covered by a dense forest, with about 80% being introduced eucalyptus trees, the older trees are now over 100 feet tall. The mountain is within San Franciscos fog belt, receiving fog throughout the summer, the tall trees precipitate the fog, with the moisture being absorbed by the duff and tree roots, and the forest remains damp through the summer months. It receives some 30 to 40% of its moisture from fog drip, there is a dense understory of non-native Himalayan blackberry and several other plants. The forest provides habitat for a number of species, including great horned owls. Over thirty species were recorded in a morning of bird watching. The 19-acre city-owned portion of Mount Sutro and the eucalyptus forest, Rotary Meadow, a garden of California native plants, is at the summit within the Mount Sutro Open Space Reserve. It was funded by a $100,000 grant from the Rotary Club, the garden is maintained by the Sutro Stewards volunteers, and has water supplied by UCSF. It is accessible by paved road from Clarendon Avenue through UCSFs Aldea San Miguel housing complex, most of the gardens plants reach peak bloom in the spring. It is encircled by the Eucalyptus forest, and therefore has no views of the city, as the nearby non-forested Twin Peaks, the hill and forest are accessible by hiking trails, many of which are suitable for mountain bikes. In 2009, UCSF applied for a grant from FEMA to remove a majority of the trees on 23% of its land, for campus. It was supported by native habitat restoration advocates, for the return and expansion of indigenous habitats that support native flora, after over four years, the first step, a preliminary Draft EIR for public review and comments, has yet to be completed by UCSF. Much of 19th century Mount Sutro was within the Rancho San Miguel of Alta California, the ranch property was acquired by Adolph Sutro in 1879, shortly after his Comstock Lode stock was bought out by his partners, the Silver Big 4. That enabled Sutro to invest in San Francisco real estate on a large scale
8.
Salesforce Tower
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Salesforce Tower, formerly known as the Transbay Tower, is a 1, 070-foot supertall office skyscraper under construction in the South of Market district of downtown San Francisco. When completed, the tower will be the tallest in San Francisco, with a top roof height of 970 feet and an overall height of 1,070 feet, it will be the second-tallest building west of the Mississippi River after the Wilshire Grand Center in Los Angeles. Developer Hines, with a proposal by architect César Pelli, was selected as the winner of a competition in 2007 to entitle. In 2012, Boston Properties acquired a 50% stake in the project, the site of the tower was in a dilapidated area, formerly used as a ground-level entrance to the San Francisco Transbay Terminal, which was demolished in 2011. The TJPA sold the parcel to Boston Properties and Hines for US$192 million, actual below-grade construction work started in late 2013. The project is a joint venture between general contractors Clark Construction and Hathaway Dinwiddie Construction, the development was originally contracted on spec, meaning the developer-owner did not have a major tenant lease secured beforehand. On April 11,2014, Salesforce. com announced that it signed a lease for 714,000 square feet on floors 1, 3–30, previously known as the Transbay Tower, the building was renamed Salesforce Tower. The lease was valued at US$560 million over 15 and a half starting in 2017. The tower is expected to be completed in 2018 and will have 61 floors, the original proposal called for a 1, 200-foot tower, but the height was later reduced. It will be the tallest building in San Francisco, surpassing the Transamerica Pyramid by more than 200 feet, the tower is expected to become the second-tallest building in the Western United States. A facebook group critical of the design gained over 700 likes. Despite the tower not being completed, San Francisco Curbed readers rated Salesforce Tower as one of the 20 ugliest buildings in the city. Many also noted their disappointment that the tower, built on formerly state-owned land and claiming the highest elevation point in San Francisco, satirical blogs have also ridiculed the tower for its provocative shape
9.
Adolph Sutro
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Adolph Heinrich Joseph Sutro was a German-American engineer, politician and philanthropist who served as the 24th mayor of San Francisco from 1895 until 1897. Born a German Jew, he moved to Virginia City, Nevada and he is today perhaps best remembered for the various San Francisco lands and landmarks that still bear his name. Born to a Jewish family in Aachen, Rhine Province, Prussia, Sutro, educated as an engineer, Sutro incorporated the Sutro Tunnel company and raised US$3 million, a considerable fortune through this work in Nevada. He included the miners in his scheme, and planned to sail to Europe to negotiate with the Parisian Bank, but the Franco-Prussian War commenced in the middle of July 1870. Sutro was stymied, but out of the blue came an offer from a London bank led by a banker named McClamont, Sutro set off blasts of dynamite. Leading the way for tunnel diggers and he fought avalanches, mud slides and poisonous gases. He dug air shafts to relieve the danger, the shafts filled with water and he fought cave-ins and solid rock. His wealth was increased by large real estate investments in San Francisco and these land investments included Mount Sutro, Lands End, and Mount Davidson, which was called Blue Mountain at the time. In 1896, Adolph Sutro built a new Cliff House, a seven story Victorian Chateau, called by some the Gingerbread Palace, great throngs of San Franciscans arrived on steam trains, bicycles, carts and horse wagons on Sunday excursions. The baths became popular despite their remote location, across the open dunes to the west of the populated areas of the city. This popularity was due to the low entry fee for visiting the Baths. The railroad grade still exists as a trail along the Lands End cliffs. Sutro managed a great increase in the value of his land investments as a direct result of the development burst that his vacationers railroad spawned. He also increased the value of his lands by planting his property at Mount Sutro with saplings of fast-growing eucalyptus and this occurred at the same time as city Supervisors granted tax-free status to forested lands within city limits. Small fragments of the forest still exist, the largest is at Mount Sutro, where 61 acres are the property of the University of California, San Francisco, and another 19 are property of the City of San Francisco. Sutros reputation as a provider of diversions and culture for the average person led the politically weak and he won on an anti-big business platform, inveighing against the tight grip that the Southern Pacific Railroad had over local businesses. Nevertheless, he was considered a failed mayor, ill suited for political work. At the time of his death, in 1898, his fortune was extensive, as a result, his heirs fought bitterly over his holdings
10.
American Broadcasting Company
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The network is headquartered on Columbus Avenue and West 66th Street in Manhattan, New York City. There are additional offices and production facilities elsewhere in New York City, as well as in Los Angeles and Burbank. Since 2007, when ABC Radio was sold to Citadel Broadcasting, ABC originally launched on October 12,1943, as a radio network, separated from and serving as the successor to the NBC Blue Network, which had been purchased by Edward J. Noble. It extended its operations to television in 1948, following in the footsteps of established broadcast networks CBS, in the mid-1950s, ABC merged with United Paramount Theatres, a chain of movie theaters that formerly operated as a subsidiary of Paramount Pictures. Leonard Goldenson, who had been the head of UPT, made the new television network profitable by helping develop, in 1996, most of Capital Cities/ABCs assets were purchased by The Walt Disney Company. The television network has eight owned-and-operated and over 232 affiliated television stations throughout the United States, most Canadians have access to at least one U. S. ABC News provides news and features content for radio stations owned by Citadel Broadcasting. In the 1930s, radio in the United States was dominated by three companies, the Columbia Broadcasting System, the Mutual Broadcasting System and the National Broadcasting Company. The last was owned by electronics manufacturer Radio Corporation of America, in 1938, the FCC began a series of investigations into the practices of radio networks and published its report on the broadcasting of network radio programs in 1940. The report recommended that RCA give up control of either NBC Red or NBC Blue, at that time, the NBC Red Network was the principal radio network in the United States and, according to the FCC, RCA was using NBC Blue to eliminate any hint of competition. Once Mutuals appeals against the FCC were rejected, RCA decided to sell NBC Blue in 1941, the newly separated NBC Red and NBC Blue divided their respective corporate assets. Investment firm Dillon, Read & Co. offered $7.5 million to purchase the network, Edward John Noble, the owner of Life Savers candy, drugstore chain Rexall and New York City radio station WMCA, purchased the network for $8 million. Due to FCC ownership rules, the transaction, which was to include the purchase of three RCA stations by Noble, would require him to resell his station with the FCCs approval, the Commission authorized the transaction on October 12,1943. Soon afterward, the Blue Network was purchased by the new company Noble founded, Noble subsequently acquired the rights to the American Broadcasting Company name from George B. Meanwhile, in August 1944, the West Coast division of the Blue Network, both stations were then managed by Don Searle, the vice-president of the Blue Networks West Coast division. The ABC Radio Network created its audience slowly, the network also became known for such suspenseful dramas as Sherlock Holmes, Gang Busters and Counterspy, as well as several mid-afternoon youth-oriented programs. S. From Nazi Germany after its conquest, to pre-record its programming, while its radio network was undergoing reconstruction, ABC found it difficult to avoid falling behind on the new medium of television. To ensure a space, in 1947, ABC submitted five applications for television station licenses, the ABC television network made its debut on April 19,1948, with WFIL-TV in Philadelphia becoming its first primary affiliate
