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Friedrich Von Hefner-Alteneck
Friedrich Heinrich Philipp Franz von Hefner-Alteneck (April 27, 1845 in Aschaffenburg – January 6, 1904 in Biesdorf near Berlin) was a German electrical engineer and one of the closest aides of Werner von Siemens. He is largely remembered for the invention of the Hefner lamp, which provided the measure of luminous intensity used in Germany, Austria and Scandinavia from 1890 to 1942. The measure was called the ''Hefnerkerze'' (HK). The Hefnerkerze was superseded in the 1940s by the modern SI unit, the candela. He was elected a member of the Royal Swedish Academy of Sciences in 1896. Notable Inventions von Hefner-Alteneck's most notable inventions were all conceptualized during his time at Siemens. * Differential arc lamp - A type of automatic-feed carbon arc lamp * Drum armature - An efficient form of winding motor rotor coils * A telegraph keyboard * The Hefner lamp Gallery File:Hefnerlampe.png, Hefner lamp The Hefner lamp, or in German ''Hefnerkerze'', is a flame lam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brackets
A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. Typically deployed in symmetric pairs, an individual bracket may be identified as a 'left' or 'right' bracket or, alternatively, an "opening bracket" or "closing bracket", respectively, depending on the Writing system#Directionality, directionality of the context. Specific forms of the mark include parentheses (also called "rounded brackets"), square brackets, curly brackets (also called 'braces'), and angle brackets (also called 'chevrons'), as well as various less common pairs of symbols. As well as signifying the overall class of punctuation, the word "bracket" is commonly used to refer to a specific form of bracket, which varies from region to region. In most English-speaking countries, an unqualified word "bracket" refers to the parenthesis (round bracket); in the United States, the square bracket. Glossary of mathematical sym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aschaffenburg
Aschaffenburg (; South Franconian: ''Aschebersch'') is a town in northwest Bavaria, Germany. The town of Aschaffenburg is not part of the district of Aschaffenburg, but is its administrative seat. Aschaffenburg belonged to the Archbishopric of Mainz for more than 800 years. The town is located at the westernmost border of Lower Franconia and separated from the central and eastern part of the ''Regierungsbezirk'' (administrative region) by the Spessart hills, whereas it opens towards the Rhine-Main plain in the west and north-west. Therefore, the inhabitants speak neither Bavarian nor East Franconian but rather a local version of Rhine Franconian. Geography Location The town is located on both sides of the Main in north-west Bavaria, bordering to Hesse. On a federal scale it is part of central Germany, just southeast of Frankfurt am Main. In the western part of the municipality, the smaller Aschaff flows into the Main. The region is also known as ''Bayerischer Untermain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biesdorf
Biesdorf is a municipality in the district of Bitburg-Prüm, in Rhineland-Palatinate, western Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe .... References Bitburg-Prüm {{BitburgPrüm-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Engineer
Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the latter half of the 19th century after commercialization of the electric telegraph, the telephone, and electrical power generation, distribution, and use. Electrical engineering is now divided into a wide range of different fields, including computer engineering, systems engineering, power engineering, telecommunications, radio-frequency engineering, signal processing, instrumentation, photovoltaic cells, electronics, and optics and photonics. Many of these disciplines overlap with other engineering branches, spanning a huge number of specializations including hardware engineering, power electronics, electromagnetics and waves, microwave engineering, nanotechnology, electrochemistry, renewable energies, mechatronics/control, and electrica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Werner Von Siemens
Ernst Werner Siemens (von Siemens from 1888; ; ; 13 December 1816 – 6 December 1892) was a German electrical engineer, inventor and industrialist. Siemens's name has been adopted as the SI unit of electrical conductance, the siemens. He founded the electrical and telecommunications conglomerate Siemens. Biography Early years Ernst Werner Siemens was born in Lenthe, today part of Gehrden, near Hannover, in the Kingdom of Hanover in the German Confederation, the fourth child (of fourteen) of a tenant farmer of the Siemens family, an old family of Goslar, documented since 1384. He was a brother of Carl Heinrich von Siemens and Carl Wilhelm Siemens, sons of Christian Ferdinand Siemens (31 July 1787 – 16 January 1840) and wife Eleonore Deichmann (1792 – 8 July 1839). Middle years After finishing school, Siemens intended to study at the Bauakademie Berlin. However, since his family was highly indebted and thus could not afford to pay the tuition fees, he chose to join the Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hefner Lamp
The Hefner lamp, or in German ''Hefnerkerze'', is a flame lamp used in photometry that burns amyl acetate. The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with a luminous intensity unit of the Hefnerkerze (HK). The lamp was specified as having a 40 mm flame height and an 8 mm diameter wick. The Hefner lamp provided the German, Austrian, and Scandinavian standard for luminosity during the late nineteenth and early twentieth centuries. The unit of light intensity was defined as that produced by the lamp burning amyl acetate with a 40 mm flame height. The light unit was adopted by the German gas industry in 1890 and known as the ''Hefnereinheit''. In 1897 it was also adopted by the Association of German Electrical Engineers under the name ''Hefnerkerze'' (HK). Germany moved to using the new candle (NC) from 1 July 1942 and the candela (cd) from 1948. :1 Hefnerkerze is about 0.920 cand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminous Intensity
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit. Measurement Photometry deals with the measurement of visible light as perceived by human eyes. The human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions (photopic vision), the eye is most sensitive to yellow-green light at 555 nm. Light with the same radiant intensity at other wavelengths has a lower luminous intensity. The curve which measures the response of the human eye to light is a defined standard, known as the luminosity function. This curve, denoted ''V''(λ) or \textstyle \overline(\lambda), is based on an average of widely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candela
The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the contributions of every wavelength of light in the source's spectrum, the contribution of each wavelength is weighted by the standard luminosity function (a model of the sensitivity of the human eye to different wavelengths). A common wax candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured. The word ''candela'' is Latin for ''candle''. The old name "candle" is still sometimes used, as in ''foot-candle'' and the modern definition of ''candlepower''. Definition The 26th General Conference on Weights and Measures (C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Swedish Academy Of Sciences
The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for promoting natural sciences and mathematics and strengthening their influence in society, whilst endeavouring to promote the exchange of ideas between various disciplines. The goals of the academy are: * to be a forum where researchers meet across subject boundaries, * to offer a unique environment for research, * to provide support to younger researchers, * to reward outstanding research efforts, * to communicate internationally among scientists, * to advance the case for science within society and to influence research policy priorities * to stimulate interest in mathematics and science in school, and * to disseminate and popularize scientific information in various forms. Every year, the academy awards the Nobel Priz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arc Lamp
An arc lamp or arc light is a lamp that produces light by an electric arc (also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, was the first practical electric light. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the incandescent light in the early 20th century. It continued in use in more specialized applications where a high intensity point light source was needed, such as searchlights and movie projectors until after World War II. The carbon arc lamp is now obsolete for most of these purposes, but it is still used as a source of high intensity ultraviolet light. The term is now used for gas discharge lamps, which produce light by an arc between metal electrodes through a gas in a glass bulb. The common fluorescent lamp is a low-pressure mercury arc lamp. The xenon arc lamp, which produces a high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1845 Births
Events January–March * January 10 – Elizabeth Barrett receives a love letter from the younger poet Robert Browning; on May 20, they meet for the first time in London. She begins writing her ''Sonnets from the Portuguese''. * January 23 – The United States Congress establishes a uniform date for federal elections, which will henceforth be held on the first Tuesday after the first Monday in November. * January 29 – ''The Raven'' by Edgar Allan Poe is published for the first time, in the '' New York Evening Mirror''. * February 1 – Anson Jones, President of the Republic of Texas, signs the charter officially creating Baylor University (the oldest university in the State of Texas operating under its original name). * February 7 – In the British Museum, a drunken visitor smashes the Portland Vase, which takes months to repair. * February 28 – The United States Congress approves the annexation of Texas. * March 1 – President John Tyler signs a bill authorizing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1904 Deaths
Nineteen or 19 may refer to: * 19 (number), the natural number following 18 and preceding 20 * one of the years 19 BC, AD 19, 1919, 2019 Films * ''19'' (film), a 2001 Japanese film * ''Nineteen'' (film), a 1987 science fiction film Music * 19 (band), a Japanese pop music duo Albums * ''19'' (Adele album), 2008 * ''19'', a 2003 album by Alsou * ''19'', a 2006 album by Evan Yo * ''19'', a 2018 album by MHD * ''19'', one half of the double album ''63/19'' by Kool A.D. * ''Number Nineteen'', a 1971 album by American jazz pianist Mal Waldron * ''XIX'' (EP), a 2019 EP by 1the9 Songs * "19" (song), a 1985 song by British musician Paul Hardcastle. * "Nineteen", a song by Bad4Good from the 1992 album '' Refugee'' * "Nineteen", a song by Karma to Burn from the 2001 album ''Almost Heathen''. * "Nineteen" (song), a 2007 song by American singer Billy Ray Cyrus. * "Nineteen", a song by Tegan and Sara from the 2007 album '' The Con''. * "XIX" (song), a 2014 song by Slipknot. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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