China 
Africa 
Explore chapters and articles related to this topic
Measurement of Pressure
Published in Pramod K. Naik, Vacuum, 2018
where g is the gravitational acceleration and is the fluid density. P is expressed in Pa if g and h are taken in MKS units. Alternatively, one end can be maintained at the atmospheric pressure and the other arm is exposed to the gas the pressure of which is to be measured. In this case the unknown pressure is obtained by subtracting the pressure due to the difference in levels from the atmospheric pressure. Many modifications have been made in the U-tube manometers by using more accurate methods such as the use of a travelling microscope on a precision travel screw. In another modification 1, a mirror mount is supported on the wall of the enlarged U-tube. The mirror is attached to an arm and floats on the mercury surface. Angular deflection of the mirror is measured as the mercury level changes. Sensitivities of the order of 1 × 10 –2 Pa to 1 × 10 –1 Pa have been reported using these modifications. The fluids used can be mercury or low vapour pressure fluids such as those used in diffusion pumps. The latter is useful for increasing the sensitivity resulting from increased height of the fluid column due to the density of the fluid which is lower than that of mercury by an order of magnitude. However, the lower density fluid can cause errors due to
Video recording
Published in John Watkinson, Television Fundamentals, 1996
When verifying the track angle produced by a new design, it is usual to develop a tape which it has recorded with magnetic fluid, and take measurements under a travelling microscope. With the very small track widths of digital recorders, it is usually necessary to compensate for skew by applying standard tension to the tape when it is being measured, or by computing a correction factor for the track angle from the modulus of elasticity of the tape.
Influence of the Er,Cr:YSGG laser and radial firing tips on the push-out bond strength of glass fiber posts
Published in J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares, Biodental Engineering V, 2019
A.I. Araújo, M. Martins, J.C. Reis Campos, A. Barros, A. Azevedo, T. Oliveira
As all posts were tapered, the area of displacement was calculated by the following formula: A = π(D + d)√(D − d)2 + h2. “D” and “d” are respectively the largest and smallest diameter of the post, whereas “h” is the height of the slice. The largest and smallest diameter of each post was measured using an optical microscope with 20:1 magnification (Travelling Microscope, Mitutoyo, Tokyo, Japan).
Effect of tool pin profiles on fatigue crack growth rate of friction stir welded joint of Al alloy 7075-T651
Published in Canadian Metallurgical Quarterly, 2022
Manoj Kumar, Shailendra Singh Bhadauria, Varun Sharma
The Compact tensile (CT) specimen for fatigue crack growth rate was prepared as per the ASTM E647 guidelines [17], as presented in Figure 4. Fatigue crack growth rate (FCGR) of weld nugget zone (WNZ) was more than heat affected zone (HAZ) [14]. Due to this, the crack tip notch (pre-crack) lies parallel to the butt line or along the WNZ. Fatigue crack growth rate experiments were conducted under uniaxial tensile loading conditions (at room temperature with stress ratio R = 0.1 at a frequency of 10 Hz) by using a servo-hydraulic fatigue testing machine (Make: MTS; Model: 370.25). The specimen was polished prior to loading in order to measure crack growth. The crack growth was monitored using a travelling microscope equipped with a web camera and video output. The longitudinal residual stress of all joints was determined using XRD, as per method.
Evaluation of mode II fatigue disbonding using Central Cut Plies specimen and distributed strain sensing technology
Published in The Journal of Adhesion, 2019
Fabricio N. Ribeiro, Marcias Martinez, Calvin Rans
The measuring of disbond length is extremely difficult to be performed on a pure mode II fatigue test and different attempts were taken during fatigue tests using cameras and a distributed fiber optic sensing system. In fatigue tests, the common approach is to observe the disbonds from the white-painted lateral face of the specimen with a high definition camera or travelling microscope. Attempts on using this approach with a white spray paint or correction fluid were unsuccessful. In the case of the spray paint, the ductile behavior of the paint did not allow it to break following the specimen’s disbond. For the correction fluid, it was easier to observe the disbonds. However, it was necessary to have a really thin and uniform layer throughout the observation area otherwise, in a thicker layer region, the disbond will grow under the correction fluid obstructing its observation. Another downside of the disbond length measurement through lateral face observation is that an unequal crack growth through width cannot be observed if only one lateral face is used. It is necessary to measure both sides.