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Topic Review
Reduction Potential
Redox potential (also known as oxidation / reduction potential, ORP, pe, [math]\displaystyle{ E_{red} }[/math], or [math]\displaystyle{ E_{h} }[/math]) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respectively. Redox potential is expressed in volts (V). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential (reduction potential is more often used due to general formalism in electrochemistry), the greater the species' affinity for electrons and tendency to be reduced.
  • 1.1K
  • 02 Nov 2022
Topic Review
Thermal Conductivity Measurement
There are a number of possible ways to measure thermal conductivity, each of them suitable for a limited range of materials, depending on the thermal properties and the medium temperature. Three classes of methods exist to measure the thermal conductivity of a sample: steady-state, time-domain, and frequency-domain methods.
  • 1.1K
  • 24 Oct 2022
Topic Review
Argonaut Class Reactor
The Argonaut class reactor is a design of small nuclear research reactor. Many have been built throughout the world, over a wide range of power levels. Its functions are to teach nuclear reactor theory, nuclear physics and for use in engineering laboratory experiments.
  • 1.1K
  • 15 Nov 2022
Topic Review
Acoustic Metamaterials in Aeronautics
Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. The potential of metamaterial-based technologies has recently caught the interest of the aeronautics community. Their effect in the presence of realistic flows in the surrounding domains, with boundary layer, turbulence, is currently a hot research topic. The interaction with flow requires a careful design of the metamaterial to avoid detrimental effects and enabling the device maximum capabilities in aeronautics.
  • 1.1K
  • 25 Jun 2021
Topic Review
Cubic Mile of Oil
The cubic mile of oil (CMO) is a unit of energy, aiming to give the general public an understanding of large quantities of energy. It is approximately equal to 1.6×1020 joule. It was created by Hew Crane of SRI International to aid in public understanding of global-scale energy consumption and resources. Large scale sources of energy include wind, solar photovoltaic, solar thermal, nuclear, hydroelectric, oil, coal, natural gas, geothermal, and biomass (primarily the burning of wood). Traditionally, many different units are commonly used to measure these sources (e.g., joules, BTUs, kilowatt hours, therms) but only some of them are familiar to a global general public, and some argue that fewer are needed and a standard should be chosen. Still, these common energy units are mainly sized for everyday activities, for example a joule is the energy required to lift a small apple one metre vertically. For regional, national, and global scales, larger energy units, such as exajoule, terawatt-hour, billion barrels of oil equivalent (BBOE) and quad are used. Derived by multiplying the small common units by large powers of ten these larger units pose additional conceptual difficulties for many citizens. Crane intended the cubic mile of oil to provide a visualizable scale for comparing the contributions of these diverse energy components as a percentage of total worldwide, energy use. In 2005, the global economy was consuming approximately 30 billion barrels (4.8 billion cubic metres; 1.3 trillion US gallons) of oil each year. Numbers of this magnitude are difficult to conceive by most people. The volume occupied by 1 trillion US gallons (3.8 billion cubic metres) is about 1 cubic mile (4.2 billion cubic metres). Crane felt that a cubic mile would be an easier concept for the general public than a trillion gallons.
  • 1.1K
  • 28 Oct 2022
Topic Review
Resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillating force is applied at a resonant frequency of a dynamic system, the system will oscillate at a higher amplitude than when the same force is applied at other, non-resonant frequencies. Frequencies at which the response amplitude is a relative maximum are also known as resonant frequencies or resonance frequencies of the system. Small periodic forces that are near a resonant frequency of the system have the ability to produce large amplitude oscillations in the system due to the storage of vibrational energy. Resonance phenomena occur with all types of vibrations or waves: there is mechanical resonance, Orbital resonance, acoustic resonance, electromagnetic resonance, nuclear magnetic resonance (NMR), electron spin resonance (ESR) and resonance of quantum wave functions. Resonant systems can be used to generate vibrations of a specific frequency (e.g., musical instruments), or pick out specific frequencies from a complex vibration containing many frequencies (e.g., filters). The term resonance (from Latin resonantia, 'echo', from resonare, 'resound') originated from the field of acoustics, particularly the sympathetic resonance observed in musical instruments, e.g., when one string starts to vibrate and produce sound after a different one is struck.
  • 1.1K
  • 27 Oct 2022
Topic Review
Continuous-Wave THz Imaging
Terahertz (THz) spectroscopy and imaging technology have seen significant developments in the fields of biology, medical diagnosis, food safety, and nondestructive testing. Label-free diagnosis of malignant tumours has been obtained and also achieved significant development in THz biomedical imaging.
  • 1.1K
  • 07 Jan 2021
Topic Review
Acoustic Emission Spectroscopy
Acoustic emission (AE) spectroscopy has become the method of choice in many fieldsbecause it is highly sensitive. For example, the AE system constructed by the Vallen company, Germany, has a sampling rate that can reach up to 10 MHz, an arrival time resolution of 100 ns, and an energy resolution of 1.8 × 10−18V2s (i.e., in the attojoule regime, aJ) referred to sensor signal at 34 dB preamplifier gain.
  • 1.1K
  • 28 Oct 2021
Topic Review
Supersonic Flow Control
In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. 
  • 1.1K
  • 02 Dec 2021
Topic Review
Fractional Schrödinger Equation
The fractional Schrödinger equation is a fundamental equation of fractional quantum mechanics. It was discovered by Nick Laskin (1999) as a result of extending the Feynman path integral, from the Brownian-like to Lévy-like quantum mechanical paths. The term fractional Schrödinger equation was coined by Nick Laskin.
  • 1.1K
  • 24 Oct 2022
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