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Topic Review
List of Rooftop Photovoltaic Installations
This lists large-scale rooftop photovoltaic installation projects. Photovoltaic arrays in buildings are often either integrated into them, or mounted on to their roofs. Arrays are most often retrofitted into existing buildings, usually mounted on top of the existing roof structure. In 2010, more than four-fifths of the 9,000 MW of solar PV operating in Germany was installed on rooftops. Most of the large-scale stations are not installed on the roofs, but rather integrated are ground-mounted. Most rooftop applications are done in small and medium-sized installations for consumption within the buildings that host the arrays. There are many significant installation projects which have been completed and many are under construction or proposed. The following lists the rooftop photovoltaic installation projects that are larger than 1 MW in total installation size. It does not include rooftop installations of non-building structures such as detached carports and tunnels.
  • 1.1K
  • 12 Oct 2022
Topic Review
D0 Experiment
The DØ experiment (sometimes written D0 experiment, or DZero experiment) consists of a worldwide collaboration of scientists conducting research on the fundamental nature of matter. DØ was one of two major experiments (the other is the CDF experiment) located at the world's second highest-energy accelerator, the Tevatron Collider at the Fermilab in Batavia, Illinois, USA. The research is focused on precise studies of interactions of protons and antiprotons at the highest available energies. It involves an intense search for subatomic clues that reveal the character of the building blocks of the universe.
  • 710
  • 11 Oct 2022
Topic Review
CAPSTONE (Spacecraft)
Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) is a lunar orbiter that will test and verify the calculated orbital stability planned for the Gateway space station. The spacecraft is a 12-unit CubeSat that will also test a navigation system that will measure its position relative to NASA's Lunar Reconnaissance Orbiter (LRO) without relying on ground stations.
  • 527
  • 11 Oct 2022
Topic Review
4D Scanning Transmission Electron Microscopy
4D scanning transmission electron microscopy (4D STEM) is a subset of scanning transmission electron microscopy (STEM) which utilizes a pixelated electron detector to capture a convergent beam electron diffraction (CBED) pattern at each scan location. This technique captures a 2 dimensional reciprocal space image associated with each scan point as the beam rasters across a 2 dimensional region in real space, hence the name 4D STEM. Its development was enabled by evolution in STEM detectors and improvements computational power. The technique has applications in visual diffraction imaging, phase orientation and strain mapping, phase contrast analysis, among others. The name 4D STEM is common in literature, however it is known by other names: 4D STEM EELS, ND STEM (N- since the number of dimensions could be higher than 4), position resolved diffraction (PRD), spatial resolved diffractometry, momentum-resolved STEM, "nanobeam precision electron diffraction", scanning electron nano diffraction, nanobeam electron diffraction, or pixelated STEM.
  • 1.4K
  • 11 Oct 2022
Topic Review
Nuclear Clock
A nuclear clock or nuclear optical clock is a notional clock that would use the frequency of a nuclear transition as its reference frequency, in the same manner as an atomic clock uses the frequency of an electronic transition in an atom's shell. Such a clock is expected to be more accurate than the best current atomic clocks by a factor of about 10, with an achievable accuracy approaching the 10−19 level. The only nuclear state suitable for the development of a nuclear clock using existing technology is thorium-229m, a nuclear isomer of thorium-229 and the lowest-energy nuclear isomer known. With an energy of about 8 eV, the corresponding ground-state transition is expected to be in the vacuum ultraviolet wavelength region around 150 nm, which would make it accessible to laser excitation.
  • 285
  • 11 Oct 2022
Topic Review
Quantum Vacuum Thruster
A quantum vacuum thruster (QVT or Q-thruster) is a theoretical system hypothesized to use the same principles and equations of motion that a conventional plasma thruster would use, namely magnetohydrodynamics (MHD), to make predictions about the behavior of the propellant. However, rather than using a conventional plasma as a propellant, a QVT would interact with quantum vacuum fluctuations of the zero-point field. The concept is controversial and generally not considered physically possible. However, if QVT systems were possible they could eliminate the need to carry propellant, being limited only by the availability of energy.
  • 2.9K
  • 11 Oct 2022
Topic Review
Fiscal Year
A fiscal year (or financial year, or sometimes budget year) is used in government accounting, which varies between countries, and for budget purposes. It is also used for financial reporting by businesses and other organizations. Laws in many jurisdictions require company financial reports to be prepared and published on an annual basis, but generally do not require the reporting period to align with the calendar year (1 January to 31 December). Taxation laws generally require accounting records to be maintained and taxes calculated on an annual basis, which usually corresponds to the fiscal year used for government purposes. The calculation of tax on an annual basis is especially relevant for direct taxation, such as income tax. Many annual government fees—such as Council rates, license fees, etc.—are also levied on a fiscal year basis, while others are charged on an anniversary basis. Some companies—such as Cisco Systems—end their fiscal year on the same day of the week each year, i.e. the day that is closest to a particular date (for example, the Friday closest to 31 December). Under such a system, some fiscal years will have 52 weeks and others 53 weeks. The calendar year is used as the fiscal year by about 65% of publicly traded companies in the United States and for a majority of large corporations in the UK. It's the case in many countries around the world with a few exceptions, for example, Australia, New Zealand, and Japan. Many universities have a fiscal year which ends during the summer to align the fiscal year with the academic year (and, in some cases involving public universities, with the state government's fiscal year), and because the university is normally less busy during the summer months. In the northern hemisphere this is July to the next June. In the southern hemisphere this is calendar year, January to December. Some media/communication-based organizations use a broadcast calendar as the basis for their fiscal year. The fiscal year is usually denoted by the calendar year in which it ends, so United States federal government spending incurred on 14 November 2022 would belong to fiscal year 2023, operating on a fiscal calendar of October–September.
  • 2.3K
  • 11 Oct 2022
Topic Review
SCOP Formalism
The SCOP formalism or State Context Property formalism is an abstract mathematical formalism for describing states of a system that generalizes both quantum and classical descriptions. The formalism describes entities, which may exist in different states, which in turn have various properties. In addition there is a set of "contexts" (corresponding to measurements) by which an entity may be observed. The formalism has primarily found use outside of physics as a theory of concepts, in particular in the field of quantum cognition, which develops quantum-like models of cognitive phenomena (such as the conjunction fallacy) that may seem paradoxical or irrational when viewed from a perspective of classical states and logic.
  • 445
  • 11 Oct 2022
Topic Review
Space Travel Using Constant Acceleration
Constant acceleration is a proposed aspect of most future forms of space travel. It entails that the propulsion system of whatever kind operate continuously with a steady acceleration, rather than the brief impulsive thrusts used by chemical rockets — for the first half of the journey it constantly pushes the spacecraft towards its destination, and for the last half of the journey it constantly uses backthrust, so that the spaceship arrives at the destination at a standstill.
  • 2.9K
  • 11 Oct 2022
Topic Review
Metasurfaces for Sensing Applications
Photonic devices (sensors, in particular) require that an efficient dynamic control of light at nanoscale through field (electric or optical) variation using substitute low-loss materials. One such option may be plasmonic metasurfaces. Metasurfaces are arrays of optical antenna-like anisotropic structures (sub-wavelength size), which are designated to control the amplitude and phase of reflected, scattered and transmitted components of incident light radiation.
  • 745
  • 11 Oct 2022
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