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Topic Review
Self-Mixing Laser Interferometry
Self-mixing or back-injection laser interferometry is an interferometric technique in which a part of the light reflected by a vibrating target is reflected into the laser cavity, causing a modulation both in amplitude and in frequency of the emitted optical beam. In this way, the laser becomes sensitive to the distance traveled by the reflected beam thus becoming a distance, speed or vibration sensor. The advantage compared to a traditional measurement system is a lower cost thanks to the absence of collimation optics and external photodiodes.
  • 826
  • 09 Nov 2022
Topic Review
Defects and Heteroatoms and Supported Graphene Layers
The possibility of using graphene-based materials as “metal-free” catalysts is attracting enormous interest, since it reduces the need for precious or rare elements currently used in heterogeneous catalysis. However, free standing  and perfect graphene is known to be “perfectly inert”, while it is now well established that there is an essential role of defects and dopants in activating its chemical properties.
  • 825
  • 02 Apr 2022
Topic Review
Shopping Hours
Customs and regulations for shopping hours for sunday (times that shops are open) vary from countries to cities.
  • 825
  • 01 Dec 2022
Topic Review
Raman Spectroscopy
Cancer still constitutes one of the main global health challenges. Novel approaches towards understanding the molecular composition of the disease can be employed as adjuvant tools to current oncological applications. Raman spectroscopy has been contemplated and pursued to serve as a noninvasive, real time, in vivo tool which may uncover the molecular basis of cancer and simultaneously offer high specificity, sensitivity, and multiplexing capacity, as well as high spatial and temporal resolution.
  • 823
  • 11 Mar 2022
Topic Review
Transwiki:Relative Density
Template:Twwp-2 Relative density is a dimensionless ratio of the densities of two materials. The term specific gravity is similar, except that the reference material is water. A relative density can help quantify the buoyancy between two materials, or determine the density of one "unknown" material using the "known" density of another material. Mathematically, relative density is expressed as: where [math]\displaystyle{ G }[/math] is the relative density, and [math]\displaystyle{ \rho }[/math] is the densities of the two materials in the same units (e.g., kg/m³, g/cm³). Relative density is dimensionless, since it is a ratio between two quantities of same unit. If the ratio is greater than 1, the object will be heavier than the same volume of the reference. If it is less than 1, it will be lighter than the reference. It is important to specify the reference material when reporting a relative density, but when the reference material is not specified it is usually understood to be water at 3.98 ° C.
  • 822
  • 15 Nov 2022
Topic Review
Orion Service Module
The Orion service module is the service module component of the Orion spacecraft, serving as its primary power and propulsion component until it is discarded at the end of each mission. In January 2013, NASA announced that the European Space Agency (ESA) will contribute the service module for Artemis 1, replacing the previous design. Based on ESA's Automated Transfer Vehicle (ATV), the new design is also known as the European service module (ESM). The service module supports the crew module from launch through separation prior to reentry. It provides in-space propulsion capability for orbital transfer, attitude control, and high altitude ascent aborts. It provides the water and oxygen needed for a habitable environment, generates and stores electrical power, and maintains the temperature of the vehicle's systems and components. This module can also transport unpressurized cargo and scientific payloads.
  • 820
  • 28 Nov 2022
Topic Review
Nonlinear Damping Identification
In recent decades, nonlinear damping identification (NDI) in structural dynamics has attracted wide research interests and intensive studies. Different NDI strategies, from conventional to more advanced, have been developed for a variety of structural types. With apparent advantages over classical linear methods, these strategies are able to quantify the nonlinear damping characteristics, providing powerful tools for the analysis and design of complex engineering structures.
  • 819
  • 05 Jan 2021
Topic Review
Electron Cloud Densitometry
Electron cloud densitometry is an interdisciplinary technology that uses the principles of quantum mechanics by the electron beam shifting effect. The effect is that the electron beam passing through the electron cloud, in accordance with the general principle of superposition of the system, changes its intensity in proportion to the probability density of the electron cloud. It gives direct visualization of the individual shapes of atoms, molecules and chemical bonds.
  • 819
  • 18 Nov 2022
Topic Review
Cerebral Palsy
Cerebral palsy (CP) is defined as a group of permanent disorders in the development of movements and postures, provoking limitations on activity, attributed to non-progressive disturbances that occurred in the development of the foetal or infant brain.
  • 818
  • 25 Nov 2021
Topic Review
Solarisation
Pseudo-solarisation (or pseudo-solarization) is a phenomenon in photography in which the image recorded on a negative or on a photographic print is wholly or partially reversed in tone. Dark areas appear light or light areas appear dark. The term is synonymous with the Sabatier effect when referring to negatives. Solarisation and pseudo-solarisation are quite distinct effects. In short, the mechanism is due to halogen ions released within the halide grain by exposure diffusing to the grain surface in amounts sufficient to destroy the latent image.
  • 818
  • 17 Oct 2022
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