scholarly journals Acetabular sector angle

2020 ◽  
Author(s):  
Joachim Feger
Keyword(s):  
Sector Angle

Morphometric assessment of hip dysplasia in a cat treated by juvenile pubic symphysiodesis

2016 ◽  
Vol 29 (05) ◽  
pp. 433-438
Author(s):  
John Culvenor ◽  
Craig Bailey ◽  
Alen Lai
Keyword(s):  
Computed Tomography ◽  
Case Report ◽  
Hip Dysplasia ◽  
Simple Procedure ◽  
Promising Treatment ◽  
Design Case ◽  
Sector Angle ◽  
Morphometric Assessment ◽  
Acetabular Rim

SummaryObjective: To quantitatively evaluate the change of the coxofemoral joints using computed tomography and distraction index in a cat with hip dysplasia treated by juvenile pubic symphysiodesis.Study Design: Case report.Animal: Eighteen-week-old female entire Maine Coon cat.Results: Juvenile pubic symphysiodesis resulted in changes in the distraction index, acetabular angle, dorsal acetabular rim angle, dorsal acetabular sector angle, and clinical improvement at the six month follow-up. No intra-operative or postoperative complications were recorded.Conclusions: Juvenile pubic symphysiodesis performed at 18 weeks of age resulted in improvement in hip joint conformation and hip laxity in a dysplastic cat.Clinical relevance: Juvenile pubic symphysiodesis may be a promising treatment for feline hip dysplasia and is a safe and technically simple procedure to perform. Further investigations are warranted.

Large deflection analysis of clamped annular sector plates

1984 ◽  
Vol 19 (1) ◽  
pp. 1-8 ◽  
Author(s):  
R S Srinivasan ◽  
V Thiruvenkatachari
Keyword(s):  
Integral Equation ◽  
Parametric Study ◽  
Large Deflection ◽  
Large Deflections ◽  
Lateral Loads ◽  
Bending Stresses ◽  
Deflection Analysis ◽  
Annular Sector ◽  
Newton Raphson ◽  
Sector Angle

Thin annular sector plates undergoing large deflections due to lateral loads are considered in this paper. For such plates exact solutions are not available. A matrix method using integral equation of beams and the Newton Raphson procedure has been adopted for the analysis of clamped annular sector plates. Numerical values for the deflection, the membrane and the bending stresses at the interior of the plate, and the bending stresses at the edges of the plate are obtained. A parametric study has been carried out by varying the sector angle from 30 to 90 degrees in steps of 30 degrees, and the ratio of the inner and outer radii from 0 to 0.6 in steps of 0.2. The results are presented in non-dimensional graphical format.

Critical Pressure of Spherical Shell Acrylic Windows Under Short-Term Pressure Loading

1969 ◽  
Vol 91 (3) ◽  
pp. 573-584
Author(s):  
J. D. Stachiw
Keyword(s):  
Spherical Shell ◽  
Atmospheric Pressure ◽  
Convex Surface ◽  
Low Pressure ◽  
Full Scale ◽  
Pressure Loading ◽  
Short Term ◽  
Model Scale ◽  
Hydrostatic Loading ◽  
Sector Angle

Model and full scale acrylic windows in the form of spherical shell lenses with parallel convex and concave surfaces have been imploded by loading their convex surface hydro-statically at 650 psi/min rate while their concave surface was exposed to atmospheric pressure. The thickness of the model scale windows varied from 0.250 to 1.200 in. and of the full scale windows from 0.564 to 4.000 in., while the included spherical sector angle of the lens varied from 30 to 180 degrees in thirty degree increments. The low pressure face diameters of the model scale windows varied from 1.423 to 5.500 in., while those of the full scale windows varied from 6.200 to 35.868 in. In addition to critical pressures, displacement of the lens under hydrostatic pressure has been recorded and plotted as functions of pressure. The critical pressures of spherical acrylic windows have been found to be consistently higher than those of conical or flat disc acrylic windows of same thickness and low pressure face diameter subjected to short-term hydrostatic loading.

Experimental Evaluation of Heavy Fan-High-Pressure Compressor Interaction in a Three-Shaft Engine: Part II—Analysis of Distortion and Fan Loading

1986 ◽  
Vol 108 (1) ◽  
pp. 171-174
Author(s):  
A. Scha¨ffler ◽  
D. C. Miatt
Keyword(s):  
High Pressure ◽  
Rotating Stall ◽  
Interesting Insight ◽  
High Pressure Compressor ◽  
Engine Part ◽  
Distortion Analysis ◽  
Core Section ◽  
Sector Angle ◽  
Insight Into ◽  
Pressure Compressor

Analysis of a severe rotating-stall phenomenon encountered in the fan core section of a three-shaft low bypass engine revealed interesting insight into the growth and circumferential extension of the stall cells immediately before surge of the high-pressure compressor was induced. The effect of a rotating distortion in contrast to the usually encountered stationary distortion is highlighted. The rotating distortion changes the time and hence the effectively felt distortion sector angle depending on a co- or contra-rotational arrangement of the distorting and the distorted compressor. The analysis shows that a contra-rotational arrangement provides a more stable and tolerant situation against that type of distortion. Analysis of the fan loading shows the static temperature rise coefficient to be the most descriptive for the fan rotor 1 hub section which initiated the rotating-stall mechanism.

Thermal Postbuckling of Temperature-Dependent Functionally Graded Nanocomposite Annular Sector Plates Reinforced by Carbon Nanotubes

2020 ◽  
pp. 2150026
Author(s):  
Raheb Gholami ◽  
Reza Ansari
Keyword(s):  
Carbon Nanotubes ◽  
Critical Temperature ◽  
Temperature Rise ◽  
Functionally Graded ◽  
Mode Shapes ◽  
Geometrical Parameters ◽  
Temperature Dependent ◽  
Annular Sector ◽  
Thermal Postbuckling ◽  
Sector Angle

In this study, the thermal buckling and postbuckling of functionally graded (FG) nanocomposite annular sector plates reinforced by carbon nanotubes (CNTs) are numerically analyzed. The effective material properties of FG nanocomposite are temperature-dependent (TD) and evaluated via the modified micromechanical method and rule of mixture. Based on the higher-order shear deformation theory (HSDT) and using the principle of virtual work and variational differential quadrature (VDQ) approach, the unified weak form of discretized nonlinear governing equilibrium equations is derived. Then, by using the linear part of equations and solving the derived eigenvalue problem, the critical temperature rise and associated mode shapes are obtained, which are used as the initial guess in solving the nonlinear thermal postbuckling problem. The pseudo-arc-length method and an iterative solver are employed to obtain the nonlinear thermal postbuckling equilibrium path of the FG nanocomposite annular sector plates. The influences of geometrical parameters, boundary conditions (BCs), CNT volume fraction, and CNT distribution pattern on the critical temperature rise and thermal postbuckling behavior of the FG nanocomposite annular sector plates are evaluated and discussed. Also, comparisons are made between the results considering the TD and temperature-independent (TID) properties. It is demonstrated that for higher values of sector angle, the effect of sector angle on the critical temperature rise and thermal postbuckling path is negligible. Moreover, by increasing the sector angle, the effect of BCs of straight edges vanishes, and the critical temperature rise and thermal postbuckling curves of for BCs of CSCS and SCSC approach those for CCCC and SSSS ones.

scholarly journals ACETABULAR VERSION INCREASES DURING ADOLESCENCE SECONDARY TO A REDUCTION IN ANTERIOR FEMORAL HEAD COVERAGE

2019 ◽  
Vol 7 (3_suppl) ◽  
pp. 2325967119S0001
Author(s):  
Sasha Carsen ◽  
George Grammatopoulos ◽  
Paul Jamieson ◽  
Kawan Rakhra ◽  
Johanna Dobransky ◽  
...  
Keyword(s):  
Femoral Head ◽  
Acetabular Anteversion ◽  
Femoral Head Coverage ◽  
Range Of Movement ◽  
Patient Factors ◽  
Mri Scan ◽  
Acetabular Version ◽  
The Mean ◽  
Sector Angle

The understanding of the underlying mechanisms leading to FAI continues to evolve; it is evident that both the femoral (cam, retroversion) and acetabular (pincer, retroversion) anatomy may contribute to its development. Several studies have demonstrated the development of cam morphology during the growing years of the skeleton and its association with increased activity during the adolescence years. However, considerably less is known about the development of the acetabulum and what changes occur during the adolescent years, which appear to be the key developmental stage. Retrospective cross-sectional studies derived from CT-data (hence missing cartilaginous portions of the growing skeleton) noted that acetabular version increased with skeletal maturity – the authors noted that the posterior rim increased however recognised that this may have to do with the inability to detect the cartilage posteriorly. A recent MRI-based study, with MRIs performed at the 1-year interval of various developmental stages, showed that the acetabular version increases around adolescence, but did not identify how this may occur. Furthermore, none of the above studies accounted for the individual demographic data, the individual’s physical activity, or the femoral-sided anatomy. The aims of this prospective longitudinal study were to determine how 1. Acetabular version and 2. Coverage to the femoral head the acetabulum provides change during the adolescent years. Furthermore, we aimed to determine whether patient factors (BMI, activity levels) or the femoral-sided anatomy contribute to any of the changes observed. METHODS: 19 volunteers (38 hips) were recruited. The mean age of the cohort was 10.5±1.3 years old and 10 patients were female (52%). The volunteers underwent clinical examination (BMI, range of movement assessment) and a MRI scan of both hips. All participants presented for further clinical examination of both hips and a second MRI scan at an interval of 6 ± 2 years. The mean age at follow-up was 16.6 ±1.3. At the follow-up visit, volunteers were also asked to fill in the HSS Pediatric Functional Activity Brief Scale (Pedi-FABS) questionnaire, which reflects the level of physical activity of each volunteer. Assessments of MRI included the status of the tri-radiate cartilage complex (TCC) (Oxford Classification I – III: open – closed), the acetabular anteversion angle at various levels in the axial plane [5 mm below the roof (top), at the middle of the femoral head (middle) and 3 equidistant slices in-between top and middle]. We measured three acetabular sector angles (anteriorly, posteriorly and superiorly) at the middle of the femoral head, reflecting degree of femoral head coverage by the acetabulum. Alpha angles anteriorly and antero-laterally were determined for each hip for each time-point. Outcome measures included how the anteversion changed at each of the five levels and the mean change overall. We also determined how the sector angles changed over time anteriorly, posteriorly and superiorly. Change in anteversion and sector angles were influenced by the BMI, range of movement measurements, the Pedi-FABS or the alpha angle measurements. RESULTS: At the baseline MRI, all hips had a Grade I (open) TCC; the TCC was Grade III (closed) by follow-up MRI in all of the hips. The acetabular anteversion increased moving, caudally, further away from the roof for both time-points (Figure 1). The mean anteversion increased from a mean of 7.4°±3.8 (initial) to 12.2°±4 (follow-up) (p<0.001). The increase in anteversion was 4.7° (range: 0 – 9). The increase in version occurred along all slices, but was greater at the rostral ¼ of the acetabulum (slices 1 and 2); 8/38 the hips had retroversion of the rostral ¼ of the acetabulum at the initial scan, whilst none of the hips had retroversion at follow-up. Females had greater anteversion than males (13.2° Vs 10.6°, p=0.04), however the change that occurred between scans was the same (4.6° Vs 5.0°; p=0.9). The anterior sector angle reduced from 72°±8 to 65°±8 (p=0.002); the posterior sector angle remained unchanged (98°±5° Vs. 97°±5) (p=0.8), whilst the superior sector angle slightly increased from 121°±4 to 124°±5° (p=0.007). The change in the anterior sector angle correlated with the change in version (rho=0.5, p=0.02). The change in version did not correlate with BMI, ROM, Pedi-FABS score or the measured alpha angles of the hip (p=0.1 – 0.6). DISCUSSION: The native acetabulum orientation changes around adolescence, with the version significantly increasing. The version increases as a result of a reduction of the femoral head coverage anteriorly (rather than an increase in posterior femoral head coverage). Therefore, if the normal developmental change did not occur, the associated retroversion would be related to anterior wall over-coverage rather than posterior deficiency. We identified no patient factors (BMI, activity level, range of movement) or proximal femoral anatomical factors (alpha angles) that were associated with this change. The increase in acetabular version may be related with the reduction in femoral version that occurs over the same period and hence further study is necessary.

Subsampling sector plots

2019 ◽  
Vol 49 (9) ◽  
pp. 1159-1164
Author(s):  
N.J. Smith ◽  
K. Iles ◽  
K. Raynor
Keyword(s):  
Natural Regeneration ◽  
Sampling Design ◽  
Sampling Strategies ◽  
Pivot Point ◽  
Fixed Angle ◽  
Fixed Area ◽  
Sector Angle ◽  
Very High ◽  
Increase Efficiency

Sector plots are fixed-angle “sector-shaped” samples of objects, typically in small irregular polygons, with a central ray extending from sector vertex or pivot point to polygon boundary. If the number of objects in the sector plot is very high, a subsample may be used. The sector angle can be reduced, or small fixed-area “subplots” can be installed along the central ray. The simplicity of subplot establishment is offset by additional computations that are avoided in the full sector plots. Specifically, to compute ray means or totals, trees in the plots must be weighted by the distance from the pivot point. When several rays are sampled in the same polygon, the ray totals or means should be weighted by the squared number of plots along the ray. Finally, polygon edge overlap with plots may also need correction. Different sampling strategies to avoid bias and increase efficiency are discussed. The sampling design is new to forestry and may have novel statistical applications such as subsampling dense natural regeneration.

Natural convection in a horizontal annular sector containing heat-generating porous medium

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Beatriz Machado dos Santos ◽  
Ludimila Silva Salles de Sá ◽  
Jian Su
Keyword(s):  
Porous Medium ◽  
Steady State ◽  
Natural Convection ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Stream Function ◽  
Maximum Temperature ◽  
Content Type ◽  
Annular Sector ◽  
Sector Angle

Purpose The purpose of this work is to propose the generalized integral transform technique (GITT) for the investigation of two-dimensional steady-state natural convection in a horizontal annular sector containing heat-generating porous medium. Design/methodology/approach GITT was used to investigate steady-state natural convection in a horizontal annular sector containing heat-generating porous medium. The governing equations in stream function formulation are integral transformed in the azimuthal direction, with the resulting system of nonlinear ordinary differential equations numerically solved by finite difference method. The GITT solutions are validated by comparison with fully numerical solutions by finite difference method, showing excellent agreement and convergence with low computational cost. Findings The effects of increasing Rayleigh number are more noticeable in stream function, whereas less significant for temperature. With decreasing annular sector angle from π to π/6, a reduction in the maximum temperature and stream function was noticed. While the two counter-rotating vortical structure is common for all annular sector angles investigated, the relative size of the two vortices varies with decreasing sector angle, with the vortex near the outer radius of the cavity becoming dominant. The annular sector angle affects strongly the maximum temperature and the partition of heat transfer on the inner and outer surfaces of the annular sector with heat-generating porous medium. Originality/value The strong effects of the annular sector angle on natural convection in annular sectors containing heat-generating porous medium are investigated for the first time. The proposed hybrid analytical–numerical approach can be applied in other convection problems in cylindrical or annular configurations, with or without porous medium. It shows potential for applications in practical convection problems in the nuclear and other industries.

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