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Topic Review
Ton 618
Coordinates: 12h 28m 24.97s, +31° 28′ 37.7″ Ton 618 is a hyperluminous, broad-absorption-line, radio-loud quasar and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, with a mass of 66 billion M☉.
  • 41.0K
  • 24 Nov 2022
Topic Review
TiO2 Photocatalysis
Catalysis on TiO2 nanomaterials in the presence of H2O and oxygen plays a crucial role in the advancement of many different fields, such as clean energy technologies, catalysis, disinfection, and bioimplants. Photocatalysis on TiO2 nanomaterials is well-established and has advanced in the last decades in terms of the understanding of its underlying principles and improvement of its efficiency. 
  • 349
  • 17 Jul 2023
Topic Review
Timoshenko-Ehrenfest Beam Theory
The Timoshenko-Ehrenfest beam theory was developed by Stephen Timoshenko and Paul Ehrenfest early in the 20th century. The model takes into account shear deformation and rotational bending effects, making it suitable for describing the behaviour of thick beams, sandwich composite beams, or beams subject to high-frequency excitation when the wavelength approaches the thickness of the beam. The resulting equation is of 4th order but, unlike Euler–Bernoulli beam theory, there is also a second-order partial derivative present. Physically, taking into account the added mechanisms of deformation effectively lowers the stiffness of the beam, while the result is a larger deflection under a static load and lower predicted eigenfrequencies for a given set of boundary conditions. The latter effect is more noticeable for higher frequencies as the wavelength becomes shorter (in principle comparable to the height of the beam or shorter), and thus the distance between opposing shear forces decreases. Rotary inertia effect was introduced by Bresse and Rayleigh. If the shear modulus of the beam material approaches infinity—and thus the beam becomes rigid in shear—and if rotational inertia effects are neglected, Timoshenko beam theory converges towards ordinary beam theory.
  • 12.2K
  • 20 Oct 2022
Topic Review
Timoshenko Beam Theory
The Timoshenko beam theory was developed by Stephen Timoshenko early in the 20th century. The model takes into account shear deformation and rotational bending effects, making it suitable for describing the behaviour of thick beams, sandwich composite beams, or beams subject to high-frequency excitation when the wavelength approaches the thickness of the beam. The resulting equation is of 4th order but, unlike Euler–Bernoulli beam theory, there is also a second-order partial derivative present. Physically, taking into account the added mechanisms of deformation effectively lowers the stiffness of the beam, while the result is a larger deflection under a static load and lower predicted eigenfrequencies for a given set of boundary conditions. The latter effect is more noticeable for higher frequencies as the wavelength becomes shorter (in principle comparable to the height of the beam or shorter), and thus the distance between opposing shear forces decreases. If the shear modulus of the beam material approaches infinity—and thus the beam becomes rigid in shear—and if rotational inertia effects are neglected, Timoshenko beam theory converges towards ordinary beam theory.
  • 1.3K
  • 15 Nov 2022
Topic Review
Timeline of Telescope Technology
The following timeline lists the significant events in the invention and development of the telescope.
  • 680
  • 18 Nov 2022
Topic Review
Timeline of Physical Chemistry
The timeline of physical chemistry lists the sequence of physical chemistry theories and discoveries in chronological order.
  • 257
  • 21 Nov 2022
Topic Review
Timeline of Epochs in Cosmology
The timeline of cosmological epochs outlines the formation and subsequent evolution of the Universe from the Big Bang (13.799 ± 0.021 billion years ago) to the present day. An epoch is a moment in time from which nature or situations change to such a degree that it marks the beginning of a new era or age. Times on this list are measured from the moment of the Big Bang.
  • 1.6K
  • 21 Nov 2022
Topic Review
Time Regulated Dynamics
How parameters such as interaction, iteration, frequency of iteration and time can express in a simple manner a nonlinear dynamics? Considering a system with stationary PDF and ergodic properties, the mathematical framework reveals a constant oscillation of information flow in the system. Those parameters mentioned before can start chaotic process in the previous system generating infinite random sequences as Per Martin-Löf suggested in his work "Complexity oscillations in infinite binary sequences". In this way the non ergodic properties of system express observable oscillations in which time lengths regulations can be used as a tool for PDF constraint and  phase space formations.
  • 1.2K
  • 30 Oct 2020
Topic Review
Ti/Al/X/Au Au-Contained Ohmic Contact Technique
AlGaN/GaN high electron mobility transistors (HEMTs) are regarded as promising candidates for a 5G communication system, which demands higher frequency and power. Source/drain ohmic contact is one of the key fabrication processes crucial to the device performance. Firstly, Aucontained metal stacks combined with RTA high-temperature ohmic contact schemes were presented and analyzed, including process conditions and contact formation mechanisms. Considering the issues with the Au-contained technique, the overview of a sequence of Au-free schemes is given and comprehensively discussed. In addition, in order to solve various problems caused by hightemperature conditions, novel annealing techniques including microwave annealing (MWA) and laser annealing (LA) were proposed to form Au-free low-temperature ohmic contact to AlGaN/GaN HEMT. The most popular metallization schemes of ohmic contact in AlGaN/GaN HEMT is Ti/Al/X/Au, where X can be Ni, Mo, Pt, Ta, Ir, etc.
  • 1.5K
  • 28 Jun 2022
Topic Review
Three-Phase
In electrical engineering, three-phase electric power systems have at least three conductors carrying alternating current voltages that are offset in time by one-third of the period. A three-phase system may be arranged in delta (∆) or star (Y) (also denoted as wye in some areas). A wye system allows the use of two different voltages from all three phases, such as a 230/400 V system which provides 230 V between the neutral (centre hub) and any one of the phases, and 400 V across any two phases. A delta system arrangement only provides one voltage magnitude, but it has a greater redundancy as it may continue to operate normally with one of the three supply windings offline, albeit at 57.7% of total capacity. Harmonic current in the neutral may become very large if nonlinear loads are connected.
  • 565
  • 17 Oct 2022
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