1,721,363 research outputs found
Electricity in the Age of Enlightenment
No full textThe author gives a review of the historical development of electricity during the Age of Enlightenment (1600-1800), including work from William Gilbert to Benjamin Franklin
Once Upon a Time ... The Compass [Historical]
No full textSome time ago, a short article about the magnetic compass was placed on the Internet by "The Institute Alert" of the IEEE, which brought to my mind that the story of this small and simple device deserves our attention
The Conquest of the Atlantic [Historical]
No full textWe are all used to the possibilities made available by the Internet and information and communications technology (ICT), but only those of us who are at least in our 40s can truly appreciate the difference between the present day and the time when rapid long-distance bidirectional communication could only take place via telegraph, telephone, and telex. A similar revolution occurred in the late 1830s with the invention of the telegraph, the first electric technology to gain wide success. However, this pioneering equipment performed badly; with the conductivity of commercial copper around 40% lower than its present value and insulating material unreliable, it was a common practice to lay bare overhead lines hanging on wooden poles with glass or porcelain insulators
The Alternating Evolution of DC Power Transmission [Historical]
No full textAfter more than one century of evolution of alternating current (ac) and thanks to the competitive costs of alternators and transformers, today a great majority of electricity is produced, transmitted, and distributed worldwide by means of ac polyphase systems [1], [2]. Nevertheless, about 200 high-voltage direct current (HVDC) systems are spread over the world to provide services where they are more convenient than ac systems. Moreover, the number of direct current (dc) systems is increasing, primarily due to the expansion of intermitted renewable energy sources and the inherent need to provide them with storage capabilities and, secondly, because of the enhanced competitiveness of solid-state converters. These two aspects can merge to form visionary concepts such as the energy hub, which fosters medium-voltage ?direct current transmission
Two Millennia of Light: The Long Path to Maxwell's Waves
No full textThe United Nations Educational, Scientific, and Cultural Organization (UNESCO) has designated 2015 the International Year of Light and Light-Based Technologies [1]. Those of us who remember the exceptional contributions to science made by James Clerk Maxwell can be led to believe that UNESCO's choice is related to the publication of A Dynamical Theory of the Electromagnetic Field in 1865, 150 years ago. As a matter of fact, in his book, Maxwell was able to deduce the existence of electromagnetic waves, traveling as fast as light, a strong clue that light had an electromagnetic nature
The Age of Vacuum Tubes: The Conquest of Analog Communications [Historical]
No full textAfter they first appeared on the scene in the early 1900s [1], a series of improvements on vacuum tubes occurred in the second decade of the 20th century, leading them to maturity. A major advancement was introduced by an American chemist and physicist Irving Langmuir (18811957) of the GE Research Laboratory in 1912, who used his new mercury vapor diffusion pump to obtain high vacuum tubes
Analisi termica di conduttori refrigerati mediante acqua: dimensionamento delle Bobine Magnetizzanti di RFX
No full textA shining tale
No full textThe sun has given light to the Earth since the formation of the solar system 4.6 billion years ago, and through photosynthesis, it has fed almost all its life forms for at least 2.45-2.32 billion years. Photosynthesis is estimated to capture in biomass approximately 833 PWh (1012 kWh) yearly, at an average power of 95 TW-the same produced by 100,000 large-sized power stations. This is just a small fraction of the energy irradiated yearly by the sun to our planet, which receives 1,520 EWh (1015 kWh) in the upper atmosphere. Approximately 30% is reflected back into space, 20% is absorbed by clouds, and about 780 EWh (i.e., 51%) reaches the Earth's surface, either land or oceans. Out of this, a portion ranging between 438 and 13,844 PWh could be converted into useful energy with technological means, according to 2015 estimations of the United Nations Development Programme
Revolving and Evolving-Early dc Machines
Full text linkIn an age largely characterized by information and communication technology (ICT), which uses more and more feeble currents, electrical power is also experiencing a period of excellent health and heads towards a bright future. This success is largely due to electric motors, which are available in different types and powered by direct current (DC) as well as alternating current (AC) sources, provided by power grids or by inverters at variable frequencies. Their versatility and ubiquity is so wide that they can be found almost everywhere: in many household appliances, technician power tools, building fans, factory machine tools, blowers and pumps of industrial fluid systems, cableways, railway and streetcar locomotives, computer disk drives, drivers and printers and cellphone vibration alerts. Tens of billions of electric motors are produced every year, with powers ranging from a few hundredths of a milliwatt to some tens of megawatts. Their future looks bright due to the rise of electric-powered transport, which will be enforced by government measures in many countries in the coming years
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