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Salmon Creek Dam
The Salmon Creek Dam is a concrete arch dam on the Salmon Creek, northwest of Juneau, Alaska. Built in 1914, it is the world's first constant-angle arch variable radius dam. Since it was built, over 100 such dams have been constructed all over the world. The dam was designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers in 2022. The dam was built by the Alaska-Gastineau Mining Company to meet the electrical energy needs for mining operations. The dam continues to be fully functional for hydroelectric generation, as one of the drinking water sources to Juneau city and for aquaculture and fishing. When built, adoption of the constant arch design for the dam reduced costs by 20% because less concrete was needed to construct the dam. Of the two hydroelectric power stations built at the initial stage (one at the upper level and the other at the lower level) – the latter one is still in use after a new powerhouse was built adjoining t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juneau
The City and Borough of Juneau, more commonly known simply as Juneau ( ; tli, Dzánti K'ihéeni ), is the capital city of the state of Alaska. Located in the Gastineau Channel and the Alaskan panhandle, it is a unified municipality and the second- largest city in the United States by area. Juneau was named the capital of Alaska in 1906, when the government of what was then the District of Alaska was moved from Sitka as dictated by the U.S. Congress in 1900. The municipality unified on July 1, 1970, when the city of Juneau merged with the city of Douglas and the surrounding Greater Juneau Borough to form the current municipality, which is larger by area than both Rhode Island and Delaware. Downtown Juneau () is nestled at the base of Mount Juneau and across the channel from Douglas Island. As of the 2020 census, the City and Borough had a population of 32,255, making it the third-most populous city in Alaska after Anchorage and Fairbanks. Juneau experiences a daily influx o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spillway
A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that water does not damage parts of the structure not designed to convey water. Spillways can include floodgates and fuse plugs to regulate water flow and reservoir level. Such features enable a spillway to regulate downstream flow—by releasing water in a controlled manner before the reservoir is full, operators can prevent an unacceptably large release later. Other uses of the term "spillway" include bypasses of dams and outlets of channels used during high water, and outlet channels carved through natural dams such as moraines. Water normally flows over a spillway only during flood periods, when the reservoir has reached its capacity and water continues entering faster than it can be released. In contrast, an intake tower is a structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dams Completed In 1914
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions. The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. The word ''dam'' can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities, such as Amsterdam and Rotterdam. History Ancient dams Early dam building took place in Mesopotamia and the Middle East. Dams were used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buildings And Structures In Juneau, Alaska
A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, prestige, and aesthetic reasons. To better understand the term ''building'' compare the list of nonbuilding structures. Buildings serve several societal needs – primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical division of the human habitat (a place of comfort and safety) and the ''outside'' (a place that at times may be harsh and harmful). Ever since the first cave paintings, buildings have also become objects or canvasses of much artisti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arch Dams
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it. Arches may be synonymous with vaults, but a vault may be distinguished as a continuous arch forming a roof. Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture, and their systematic use started with the ancient Romans, who were the first to apply the technique to a wide range of structures. Basic concepts An arch is a pure compression form. It can span a large area by resolving forces into compressive stresses, and thereby eliminating tensile stresses. This is sometimes denominated "arch action". As the forces in the arch are transferred to its base, the arch pushes outward at its base, denominated "thrust". As the rise, i. e. height, of the arch decreases the outward thrust increases. In order to preserve arch action and prevent collapse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1914 Establishments In Alaska
This year saw the beginning of what became known as World War I, after Archduke Franz Ferdinand of Austria, heir to the Austrian throne was assassinated by Serbian nationalist Gavrilo Princip. It also saw the first airline to provide scheduled regular commercial passenger services with heavier-than-air aircraft, with the St. Petersburg–Tampa Airboat Line. Events January * January 1 – The St. Petersburg–Tampa Airboat Line in the United States starts services between St. Petersburg and Tampa, Florida, becoming the first airline to provide scheduled regular commercial passenger services with heavier-than-air aircraft, with Tony Jannus (the first federally-licensed pilot) conveying passengers in a Benoist XIV flying boat. Abram C. Pheil, mayor of St. Petersburg, is the first airline passenger, and over 3,000 people witness the first departure. * January 11 – The Sakurajima volcano in Japan begins to erupt, becoming effusive after a very large earthquake on J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alaskan Indian
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., it borders the Canadian province of British Columbia and the Yukon territory to the east; it also shares a maritime border with the Russian Federation's Chukotka Autonomous Okrug to the west, just across the Bering Strait. To the north are the Chukchi and Beaufort Seas of the Arctic Ocean, while the Pacific Ocean lies to the south and southwest. Alaska is by far the largest U.S. state by area, comprising more total area than the next three largest states (Texas, California, and Montana) combined. It represents the seventh-largest subnational division in the world. It is the third-least populous and the most sparsely populated state, but by far the continent's most populous territory located mostly north of the 60th parallel, with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tingit
The Tlingit ( or ; also spelled Tlinkit) are indigenous peoples of the Pacific Northwest Coast of North America. Their language is the Tlingit language (natively , pronounced ),"Lingít Yoo X'atángi: The Tlingit Language." ''Sealaska Heritage Institute.'' (retrieved 3 December 2009) in which the name means 'People of the Tides'.Pritzker, 208 The Russian name ' (, from a Sugpiaq-Alutiiq term ' for the worn by women) or the related German name ' may be encountered referring to the people in older historical literature, such as |
Pathogens
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ''pathogen'' came into use in the 1880s. Typically, the term ''pathogen'' is used to describe an ''infectious'' microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus. Small animals, such as helminths and insects, can also cause or transmit disease. However, these animals are usually referred to as parasites rather than pathogens. The scientific study of microscopic organisms, including microscopic pathogenic organisms, is called microbiology, while parasitology refers to the scientific study of parasites and the organisms that host them. There are several pathways through which pathogens can invade a host. The principal pathways have different episodic time frames, but soil has the longest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Electronegativity#Pauling electronegativity, Pauling scale, behind only oxygen and fluorine. Chlorine played an important role in the experiments conducted by medieval Alchemy, alchemists, which commonly involved the heating of chloride Salt (chemistry), salts like ammonium chloride (sal ammoniac) and sodium chloride (common salt), producing various chemical substances containing chlorine such as hydrogen chloride, mercury(II) chloride (corrosive sublimate), and hydrochloric acid (in the form of ). However ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulic Head
Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, at the entrance (or bottom) of a piezometer. In an aquifer, it can be calculated from the depth to water in a piezometric well (a specialized water well), and given information of the piezometer's elevation and screen depth. Hydraulic head can similarly be measured in a column of water using a standpipe piezometer by measuring the height of the water surface in the tube relative to a common datum. The hydraulic head can be used to determine a ''hydraulic gradient'' between two or more points. "Head" in fluid dynamics In fluid dynamics, ''head'' is a concept that relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid. From Bernoulli's principle, the total energy at a given point in a fluid i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminum combined. Globally, the ready-mix concrete industry, the largest segment of the concrete market, is projected to exceed $600 billion in revenue by 2025. This widespread use results in a number of environmental impacts. Most notably, the production process for cement produces large volumes of greenhouse gas emissions, leading to net 8% of global emissions. Other environmental concerns include widespread illegal sand mining, impacts on the surrounding environment such as increased surface runoff or urban heat island effect, and potential public health implications from toxic ingredients. Significant research and development is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
