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Glass Processing and Properties
Published in Debasish Sarkar, Ceramic Processing, 2019
Quantitative estimation can predict the physical significance of such optical features, and therefore, several parameters for different-colored glass having a consistent thickness of 5.66 mm (as an example) are tabulated in Table 8.8. The refractive index or index of refraction is a measure of the bending of a ray of light when it passes from one medium into another. The refractive index n is defined as the ratio of the sine of the angle of incidence to the sine of the angle of refraction; i.e., n = sin i/sin r, where i, the angle of incidence of a ray in vacuum, equals the angle between the incoming ray and the normal (the perpendicular to the surface of a medium), and r, the angle of refraction, equals the angle between the ray in the medium and the normal. The refractive index is also equal to the velocity of light c of a given wavelength in empty space divided by its velocity v in a substance, or n = c/v. Some important standard refractive index data at 22°C are given in Table 8.9.
Computer-Based Instrumentation: Sensors for In-Line Measurements
Published in Gauri S. Mittal, Computerized Control Systems in the Food Industry, 2018
The refraction index of a medium is the ratio between the speed of light in a vacuum and the speed through the medium. Thus it will be always >1, as light travels fastest in a vacuum. The refractive index of a liquid is a function of both its concentration and temperature. For refractive index measurement, liquid food enters the cavity through capillary action, and it changes spectral modulation due to change in effective path length. Refractive index sensing assists in controlling processes such as extraction and evaporation, as refractive index is a function of concentration. Similarly, real-time monitoring of oil hydrogenation is also feasible [7]. An in-line refractometer has been used to measure the cholesterol concentration in egg products, and Brix levels in orange juice [3].
Fundamentals of Audio and Acoustics
Published in Douglas Self, Audio Engineering Explained, 2012
Audio practitioners are in the wave business. A wave is produced when a medium is disturbed. The medium can be air, water, steel, the earth, etc. The disturbance produces a fluctuation in the ambient condition of the medium that propagates as a wave that radiates outward from the source of the disturbance. If one second is used as a reference time span, the number of fluctuations above and below the ambient condition per second is the frequency of the event, and is expressed in cycles per second, or Hertz. Humans can hear frequencies as low as 20 Hz and as high as 20,000 Hz (20 kHz). In an audio circuit the quantity of interest is usually the electrical voltage. In an acoustical circuit it is the air pressure deviation from ambient atmospheric pressure. When the air pressure fluctuations have a frequency between 20 Hz and 20 kHz they are audible to humans.
Study of effects of surface preparation on carbon-fiber-reinforced-polymer (CFRP) Single Lap Joints (SLJ) using positioning of gates in ultrasonic signals
Published in The Journal of Adhesion, 2022
Laxmikant Sarjerao Mane, M R Bhat
Figure 11 shows ultrasonic wave travel in adherend material. Ultrasonic waves are propagated in water till it impinges on the composite’s top surface where it gets partially reflected and partially transmitted. Waves further encounter partial reflection and partial transmission at the back surface. The transmission and reflection of ultrasonic waves at each interface depend on acoustic impedances of two media expressed as a product of the density of a material (ρ) and sound speed (V) in that material [as seen in Eq. (2)]. If impedance mismatch is significant, reflection at the interface of two mediums will be greater [Eq. (3)]. Reflection coefficient for a composite-adhesive interface and transmission coefficient for a composite-adhesive interface is given below:
Investigation of surface adsorption and thermodynamic properties of 1-tetradecyl-3-methylimidazolium bromide in the absence and presence of tetrabutylammonium bromide in aqueous medium
Published in Journal of Dispersion Science and Technology, 2022
Harsh Kumar, Gagandeep Kaur, Shweta Sharma
The refractive index is actually the measure of the bending of a ray of light when it passes from one medium into another. This important property can also be utilized for the determination of CMC. This is due to the fact that the monomers of surfactants have a lower value of the refractive index as compared to formed micelle. From the graph of refractive index versus concentration of [C14mim][Br] represented in Figure 4, it can be observed that below CMC, the values of refractive index increases rapidly with the addition of [C14mim][Br], but as the [C14mim][Br] concentration approaches the point of CMC, the rate of increase of refractive index with the concentration of [C14mim][Br] decreases. Thus, a breakpoint is obtained in the graph and the concentration of [C14mim][Br] corresponding to this breakpoint gives the value of CMC of [C14mim][Br].[51] The obtained values of the refractive index for all the studied systems are reported in Table 5. The value of CMC of [C14mim][Br] obtained by utilizing refractive index measurements is reported in Table 6.
A package-less SAW RFID sensor concept for structural health monitoring
Published in Mechanics of Advanced Materials and Structures, 2021
Hugo Chambon, Pascal Nicolay, Cécile Floer, Ayech Benjeddou
SAW sensors use comb-shaped inter digital transducers (IDT) to generate surface waves on a piezoelectric medium. The velocity of the waves is essentially affected by changes in the material properties of the propagation medium. That’s why these devices are sensitive to temperature, stress and strain [5, 6] as well as to their surface-states (adsorption, pollution, degradation, etc.). Moreover, they have to be connected to an antenna. Therefore, they must be packaged. However, the housing can fail in many ways and constitutes one of the main weak points of a SAW sensor. That is why a new kind of SAW devices was recently proposed to get rid of the housing issue [7, 8]. In the latter, multilayered structures are used to guide and protect the wave below the surface. Housings are no longer needed. These ‘package-less’ structures have the potential to strongly increase the reliability and ease-of-integration of SAW sensors, while reducing their development time and cost.