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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.
  • 563
  • 17 Oct 2022
Topic Review
Thin-Film Magnetoelastic Materials Based Devices
Thin-film magnetoelastic materials, which couple the magnetization and strain together, have recently attracted ever-increasing attention due to their key roles in magnetoelectric applications. This review starts with the fabrication and characterization techniques in the field of magnetoelastic materials and introduces various kinds of devices utilizing ME effect.
  • 2.6K
  • 04 Nov 2020
Topic Review
Thin-Film Dip-Coating Methods
Coating is the way of incorporating a thin coating of material into a substrate by deposition in either the liquid phase (solution) or the solid phase (powder or nanoparticles), dip-Coating is one of them.
  • 5.9K
  • 10 Aug 2022
Topic Review
Thin Films of Sn Perovskites
Compared to Pb-based perovskites solar cells (PSCs), tin-based perovskite solar cells (TPSCs) exhibit a much lower power conversion energy (PCE), mainly due to the poor film quality, correlated degradation, and detrimental effects. Perovskite films are often fabricated from solutions due to ease of fabrication. In order to create a high-performance tin-based PSC, it is imperative to form dense, compact, well-crystalline perovskite films. Many ways have been proposed to resolve the instabilities of tin-based perovskites. The first step to enhance the stability of the device is to gain a deeper understanding of the degradation mechanisms. Earlier, the researchers briefly pointed out the effects of moisture, oxygen, illumination, ion migration, and chemical reactions which are the most common causes of degradation in perovskite halides.
  • 283
  • 20 Apr 2023
Topic Review
Thermoporometry and Cryoporometry
Thermoporometry and cryoporometry are methods for measuring porosity and pore-size distributions. A small region of solid melts at a lower temperature than the bulk solid, as given by the Gibbs–Thomson equation. Thus, if a liquid is imbibed into a porous material, and then frozen, the melting temperature will provide information on the pore-size distribution. The detection of the melting can be done by sensing the transient heat flows during phase transitions using differential scanning calorimetry – DSC thermoporometry, measuring the quantity of mobile liquid using nuclear magnetic resonance – NMR cryoporometry (NMRC) or measuring the amplitude of neutron scattering from the imbibed crystalline or liquid phases – ND cryoporometry (NDC). To make a thermoporometry / cryoporometry measurement, a liquid is imbibed into the porous sample, the sample cooled until all the liquid is frozen, and then warmed until all the liquid is again melted. Measurements are made of the phase changes or of the quantity of the liquid that is crystalline / liquid (depending on the measurement technique used). The techniques make use of the Gibbs–Thomson effect: small crystals of a liquid in the pores melt at a lower temperature than the bulk liquid : The melting point depression is inversely proportional to the pore size. The technique is closely related to that of use of gas adsorption to measure pore sizes but uses the Gibbs–Thomson equation rather than the Kelvin equation. They are both particular cases of the Gibbs Equations (Josiah Willard Gibbs): the Kelvin equation is the constant temperature case, and the Gibbs–Thomson equation is the constant pressure case.
  • 940
  • 29 Sep 2022
Topic Review
Thermodynamics of the Universe
The thermodynamics of the universe is dictated by which form of energy dominates it - relativistic particles which are referred to as radiation, or non-relativistic particles which are referred to as matter. The former are particles whose rest mass is zero or negligible compared to their energy, and therefore move at the speed of light or very close to it; the latter are particles whose kinetic energy is much lower than their rest mass and therefore move much slower than the speed of light. The intermediate case is not treated well analytically.
  • 918
  • 09 Nov 2022
Topic Review
Thermodynamics and an Introduction to Thermostatistics
Thermodynamics and an Introduction to Thermostatistics is a textbook written by Herbert Callen that explains the basics of classical thermodynamics and discusses advanced topics in both classical and quantum frameworks. The textbook contains three parts, each building upon the previous. The first edition was published in 1960 and a second followed in 1985.
  • 314
  • 22 Nov 2022
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