Effect of the Continuous Traverse Trajectory and Dynamic Error of the Vane Anemometer on the Accuracy of Average Velocity Measurements at the Cross-Section of the Mine Heading – Model-Based Testing

2014 ◽  
Vol 59 (4) ◽  
pp. 1051-1060 ◽  
Author(s):  
Paweł Jamróz

Abstract This paper discusses the problem of measuring the average velocity at the cross-section of mine heading with the use of the continuous traverse method. Based on model testing, it has been shown that measurement signals, obtained along the traversing trajectory, belong to the group of non-stationary signals. The methodology of the traversing method measurements, with the aspect of capabilities of measuring instruments used for that purpose, has been analysed. Results of simulation tests concerning the dynamic response of a vane anemometer to the measurement signal for selected trajectories of the continuous traverse have been presented. For this purpose, a velocity profile presenting an expanded stream of undisturbed air flow in the excavation has been used. Attention has been paid to the problem of selecting an adequate trajectory of anemometer movement, as the value of the velocity measured at the cross-section depends on the trajectory

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Mehran Khaki Jamei ◽  
Mohsen Heydari Alashti ◽  
Morteza Abbasi ◽  
Aliosat EbrahimNejad ◽  
Mohammad Hasan Taheri

AbstractThe present study aims to investigate the effect of the round edge on the laminar Newtonian fluid that flows through a channel. As an innovation, the sine and cosine transform functions are employed to solve the momentum governing equation in Cartesian and Cylindrical coordinates. Owing to the duct symmetric, only the quarter of the cross-section (θ = 0 to π/2) is analyzed. The analytical correlations for velocity distribution in both coordinates are provided; afterward, the effect of the round edge on the velocity profile has been investigated. It can be concluded that if a circular cross-section is replaced with a non-circular cross-section, the velocity profile becomes more uniform and less velocity variation is observed. Further, with a constant pressure gradient, among rectangular, round edge and circular cross-sections, the maximum velocity in a circular cross-section becomes minimum. In addition, it is observed that for the same pressure difference, an increase of m value leads to the higher average velocity and mass flow.


1995 ◽  
Vol 48 (1) ◽  
pp. 79
Author(s):  
Frank Di Marzio ◽  
Jakub Szajman ◽  
Alex Mazzolini

A fibre optic sensor system for the measurement of the velocity of projectiles propelled by hot gases has been developed. It was found that fibre optic techniques have significant advantages over conventional breakwire methods in this electromagnetically noisy environment. A simple passive fibre system produced both accurate and reliable measurements of projectile velocities which, in this study, were in the range 1-3 km s-l. In addition, by using a number of fibres at different positions along the projectile path, the average velocity of the projectile can be determined at several points, and a velocity profile for the projectile motion obtained.


Author(s):  
V. Mizuhira ◽  
Y. Futaesaku

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.


Author(s):  
Tamotsu Ohno

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.


2009 ◽  
Author(s):  
Marci Culley ◽  
Holly Angelique ◽  
Courte Voorhees ◽  
Brian John Bishop ◽  
Peta Louise Dzidic ◽  
...  

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.


CFA Digest ◽  
2008 ◽  
Vol 38 (3) ◽  
pp. 55-56
Author(s):  
Kathryn Dixon Jost

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