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Musculoskeletal system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The intersections of these lines create angles that are used to evaluate the alignment of the structures forming the hip joint in the Graf classification of hip development or dysplasia: The α (alpha) angle, or bony roof angle, is that formed by the intersection of the baseline with the bony roof line. The alpha angle gives the depth of the acetabulum, to enable evaluation of the size of the bony socket. The normal value is equal to or greater than 60°; less than 60° suggests dysplasia of the acetabulum, although this does depend on age as well. A shallow acetabulum in a baby less than 12 weeks old may be due to physiological immaturity, but if found after 12 weeks of age it signifies dysplasia [77].The β (beta) angle, or cartilaginous roof angle, is that formed by the intersection of the baseline with the cartilaginous roof line. The beta angle evaluates the size of the cartilaginous roof and is useful in classifying the degree of dysplasia. Beta angles should only be assessed with the hip at rest. There is considerable variability in the measurement of this angle and it is, therefore, not always used.
Comparison between conventional and multi-sensor geotechnical core logging methods
Published in Vladimir Litvinenko, EUROCK2018: Geomechanics and Geodynamics of Rock Masses, 2018
Mahadi Bhuiyan, Kamran Esmaieli
Systematic bias in digital logging can arise from the approximation of 2D sinusoidal curves to true discontinuity geometry and the adequacy of user’s selection of these planes. However, the removal of subjectivity and human error in measurement of alpha and beta angle means that precision is greater and random bias is reduced in digital logging. If digital measurements are considered as a benchmark, then a measure of variability in manual measurements is possible. The mean difference in both dip and dip direction is greater than 10°, which is significant. For example, manual measurements of a joint set dipping at 45° would have a mean error of /− 30% (100% *13.5/45). Variability in the dip direction can appreciably influence kinematic analyses. The high maximum differences, 56° dip and 119° dip direction, occur in one interval, and may be attributed to two human errors: incorrect marking of the reference line and subjectivity in measurement of shallow-dipping discontinuities. Absolute difference in dip and dip direction is reduced considerably, after modifying the reference line in this interval from 180° to 0°. This suggests that the reference line was either not recorded at 180° or incorrectly drawn. Precision of manual measurement is more likely to reduce for the shallower discontinuities, since the dip vector becomes difficult to discern. The lab orientations of three shallow discontinuities in this interval are recorded as 10°/085°, 15°/303°, 29°/215°, whereas the digital measurements are 25°/203°, 26°/262°, and 28°/213°, respectively. The digital orientations suggest that these are part of a discontinuity set, but the low precision of lab orientations make this judgement improbable. The results suggest that the large error is due to the erroneous manual measurement.
Power fluctuation analysis for WEC farms
Published in C. Guedes Soares, Developments in Renewable Energies Offshore, 2020
Figure 5 shows the set of non-dominated solutions (Pareto front) represented in the solution space for the multi-objective optimization problem. It is important to notice that f1 has been converted to a minimization problem by changing the sign of the function evaluation. The left-top point in Figure 5 represents a Layout 3 with node distance of 20 m and beta angle of 57 deg. The layout behave as a fence spanning the largest possible wave front. This results in a higher AEP but also is a higher power fluctuation, which correspond to the solution of optimality for the single objective problem when the weight of the power fluctuation is 0. At the opposite end of the Pareto front it is possible to find mostly solutions from the Layout 2, where the efficiency of the devices from rows 5 to 20 is drastically reduced due to the shading effect. This reduced the AEP and therefore the power fluctuation. This point represents a solution with a f1 weight equal to zero. This behavior also highlight a limitation in the f2 normalization because the trivial solution is not properly avoided. The two green lines identify areas with no solution in the Pareto front. This might highlight a non-convex set, which cannot be solved using the linear scalarization adopted in this work. It might be concluded that for this particular problem a different multi-objective strategy must be used.
Critical decision making for rehabilitation of hydroelectric power plants
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Kutay Celebioglu, Ece Ayli, Oguzhan Ulucak, Selin Aradag, Jerry Westerman
II) Blade Angles: Once the meridional profile is determined, the hub, shroud, and all span curves that extend from the LE to the TE of the blade can be determined. These two critical angles plays an important role in identifying the runner’s geometry. The beta angle, also known as the blade angle, is a crucial parameter in determining the geometry of the runner blade. It is the angle formed between the camber of the runner blade and the appropriate tangent line, which is measured from the runner’s center. This angle is crucial in determining the direction of blade movement at particular locations (Celebioglu and Kaplan 2019). The position angle in a cylindrical coordinate system is represented by the wrap angle. The metal and wrap angles are defined precisely in Figure 6, as shown below.
Mapping geological configuration using geophysics data: an investigative approach in targeting iron ore, gold mineralization and other commodities, a case study of Toko-Nlokeng area (Nyong Greenstone Belt, SW Cameroon)
Published in Applied Earth Science, 2023
Yannick Saturnin Evina Aboula, Joseph Mvondo Ondoa, Paul-Désiré Ndjigui
The field works consisted of detailed geological mapping and sampling of fresh representative outcrop samples of IFs and their host rocks. In addition, core samples were collected from two representative drill holes. The cores were logged lithologically at their respective depth intervals and then study under the microscope for their petro-structural aspects along with structural measurements. A simple procedure was used to assess the reliability of the measurement of the orientation of the drill core. Two methods have been used for structural measurements and orientation: (1) the alpha and beta angle method for measuring the orientations of the drill core structures (Holcombe 2008; Blenkinsop and Doyle 2010) and (2) the structural table method which consists to reposition the core identical to the wellbore (e.g. following the direction and the drilling angle) to correctly interpret structural measurements in situ. The GeoCalculator software (http://www.holcombe.net.au/software) was used to convert angles measured from a sample into geographic structural readings. Finally, the structural elements of the outcrops and the drill cores were classified according to the different deformation phases. The polished thin sections were prepared from representative samples at Lanfang Rock Detection Technologies Ltd, Hebei (China) using conventional technics. A petrographic study was done under both transmitted and reflected light petrographic microscopes.
Stress analysis of the application of the diamond plate on the quad-joint connection: A case study on the flat plate hull of ships
Published in Cogent Engineering, 2022
Gatot Prayogo, Enggar Cahya Firdaus, Muhammad Arif Budiyanto
The load was given to the sample diamond plate on a flat plate ship by varying the angles in the diamond plate. The simulation results obtained a comparison graph between angle and stress. Figure 13 shows the angle sizes in the alpha-beta and gamma-theta used, along with the stresses that occur in the first case. In the first case, it was done by giving a concentrated load only on the diamond plate, which was applied to several diamond plate samples with different interior angles. From the graph, the optimum alpha-beta angle was around 150.8° for alpha and 149.4° for beta. From the graph, the optimum gamma-theta angle was around 169.1° for gamma and 167.9° for theta.