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Properties and applications of engineering materials
Published in Alan Darbyshire, Charles Gibson, Mechanical Engineering, 2023
Alan Darbyshire, Charles Gibson
The resistance of some materials is not much affected by temperature change. Carbon is a common example of these, which are said to be ohmic materials. With most metals, the resistance increases uniformly with temperature and they are said to be non-ohmic. The temperature coefficient of resistance of a material is a measure of the effect. It is defined as the increase in resistance per unit of its resistance at 0°C, per degree of temperature rise. It is given the symbol α (alpha), and its units are °C−1. It should not be confused with linear expansivity which has the same units and symbol.
Material removal
Published in Roger Timings, Fabrication and Welding Engineering, 2008
To complete the angles associated with cutting tools, reference must be made to the rake angle. This is given the Greek letter ‘alpha’ (α). This rake angle is very important, for it alone controls the geometry of the chip formation for any given material and, therefore, it controls the mechanics of the cutting action of the tool. The relationship of the rake angle to the angles previously discussed is shown in Fig. 6.3.
Basic bench fitting
Published in Roger Timings, Engineering Fundamentals, 2007
To complete the angles associated with cutting tools, reference must be made to the rake angle. This is given the Greek letter alpha (α). The rake angle is very important, for it alone controls the geometry of the chip formation for any given material and, therefore, it controls the mechanics of the cutting action of the tool. The relationship of the rake angle to the angles previously discussed is shown in Fig. 8.5.
Study of radon/thoron exhalation rate, soil-gas radon concentration, and assessment of indoor radon/thoron concentration in Siwalik Himalayas of Jammu & Kashmir
Published in Human and Ecological Risk Assessment: An International Journal, 2018
Manpreet Kaur, Ajay Kumar, Rohit Mehra, Rosaline Mishra
The active indoor radon and thoron concentration was measured using SMART Rn Duo radon monitor in the dwellings of 20 villages of Siwalik. To measure the active radon concentration, diffusion mode of sampling was used. Air is sampled into the scintillation cell (153 cm3) through a “progeny filter” and “Pinhole plate” eliminating radon progenies and thoron. The diffusion-time delay given by Pinhole plate does not allow the short lived thoron (220Rn, half-life 55.6 s) to pass through them acting as “thoron discriminator.” The alpha scintillations from radon and its decay products formed inside the cell are continuously counted for a user-programmable counting interval by the PMT and the associated counting electronics. The alpha counts obtained are processed by a microprocessor unit as per the developed algorithm to display the concentration of radon. The pump was kept off during the measurement of indoor radon concentration. The measurement has been carried out for about 7–8 h with the 60-min cycle to assess the build-up of radon concentration inside the accumulator volume.
Technological Development and Its Effect on IT Operations Cost and Environmental Impact
Published in International Journal of Sustainable Engineering, 2021
František Dařena, Florian Gotter
When it comes to CPU/instruction set and virtualisation, special virtualisation layers can be utilised to supply emulated environments, especially for older hardware solutions. A usual solution consists of combining virtual machine and hardware abstraction layers. Abstraction binds modern hardware solutions (not only a CPU instruction set) to legacy emulated hardware utilised by the guest system. An example of such a solution is Charon-AXP (emulating legacy platforms PDP-11, Vax, and AXP alpha server). Another way to handle incompatibilities on memory or storage architecture is using a containerised solution that some vendors provide for standard x86 and/or x64 platforms (HP UX containers) on top of classical virtualisation.