Stresses and displacements in a circular ring loaded by symmetrically spaced radial forces

2015 ◽  
Vol 8 (4) ◽  
pp. 296-303
Author(s):  
Milan Batista
Keyword(s):  
Circular Ring ◽  
Radial Forces

scholarly journals Analytical solution for torsion of cylindrical orthotropic annular wedge-shaped bars reinforced by thin shells

2021 ◽  
Author(s):  
István Ecsedi ◽  
Attila Baksa
Keyword(s):  
Analytical Solution ◽  
Cross Section ◽  
Analytical Method ◽  
Torsional Rigidity ◽  
Circular Ring ◽  
Thin Shells ◽  
Elastic Wedge ◽  
Curved Boundary ◽  
Cylindrically Orthotropic ◽  
Boundary Surfaces

AbstractThis paper deals with the Saint-Venant torsion of elastic, cylindrically orthotropic bar whose cross section is a sector of a circular ring shaped bar. The cylindrically orthotropic homogeneous elastic wedge-shaped bar strengthened by on its curved boundary surfaces by thin isotropic elastic shells. An analytical method is presented to obtain the Prandtl’s stress function, torsion function, torsional rigidity and shearing stresses. A numerical example illustrates the application of the developed analytical method.

Analysis of Probe Excited Circular Ring above Reflector in Outdoor WLAN Systems

2006 ◽  
Author(s):  
C. Phongcharoenpanich ◽  
Y. Chawanonphithak ◽  
P. Wounchoum ◽  
M. Krairiksh
Keyword(s):  
Circular Ring

scholarly journals High Throughput Centrifugal Electrospinning of Polyacrylonitrile Nanofibers for Carbon Fiber Nonwovens

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1313
Author(s):  
Andreas Hoffmann ◽  
Alexander J. C. Kuehne
Keyword(s):  
High Throughput ◽  
Carbon Nanofiber ◽  
Fiber Diameter ◽  
Carbon Precursor ◽  
Production Methods ◽  
High Throughput Method ◽  
Radial Forces ◽  
Fiber Deposition ◽  
The Impact ◽  
Pan Fibers

Carbon nanofiber nonwovens are promising materials for electrode or filtration applications; however, their utilization is obviated by a lack of high throughput production methods. In this study, we utilize a highly effective high-throughput method for the fabrication of polyacrylonitrile (PAN) nanofibers as a nonwoven on a dedicated substrate. The method employs rotational-, air pressure- and electrostatic forces to produce fibers from the inner edge of a rotating bell towards a flat collector. We investigate the impact of all above-mentioned forces on the fiber diameter, morphology, and bundling of the carbon-precursor PAN fibers. The interplay of radial forces with collector-facing forces has an influence on the uniformity of fiber deposition. Finally, the obtained PAN nanofibers are converted to carbon nonwovens by thermal treatment.

Intracorneal circular ring implant with femtosecond laser: Pocket versus tunnel

2021 ◽  
pp. 112067212199472
Author(s):  
Luis Izquierdo ◽  
Ana M Rodríguez ◽  
Ramón A Sarquis ◽  
Diego Altamirano ◽  
Maria A Henriquez
Keyword(s):  
Visual Acuity ◽  
Femtosecond Laser ◽  
Randomized Study ◽  
Circular Ring ◽  
Continuous Ring ◽  
Refractive Outcomes ◽  
Scheimpflug Imaging ◽  
Ring Segment ◽  
Intracorneal Ring Segment ◽  
Student’S T

Purpose: To evaluate and compare visual and refractive outcomes after implantation of the intracorneal continuous ring 360° arc (ICCR) versus the intracorneal ring segment 340° arc (ICRS) using femtosecond laser for central keratoconus. Setting: Research Department, Oftalmosalud, Instituto de Ojos, Lima, Peru. Methods: Randomized study that included 40 eyes of 32 patients diagnosed with central keratoconus between November 2014 and March 2015. Twenty eyes had an implantation of ICCR (MyoRing, Dioptex GmbH, Austria) through an intrastromal pocket and 20 eyes had an implantation of ICRS (Keraring, Mediphacos, Brazil) through an intrastromal tunnel. Both procedures were performed with a femtosecond laser (LDV Z6 model, Ziemer Ophthalmic Systems AG). Visual acuity (VA), refraction, and Scheimpflug imaging analysis were performed pre- and postoperatively at 1 month and 1 year. Comparisons of means were performed using the Student’s t-test. Results: At 1 year, uncorrected VA improved 0.77 LogMAR ( p < 0.001) in the ICCR group and 0.79 LogMAR ( p = 0.01) in the ICRS group; mean sphere improvement was 5.13 Diopters (D) in the ICCR group and 6.27 D in the ICRS group ( p < 0.001 both); mean Steeper Keratometry improvement was 4.24 D in the ICCR group and 5.53 D in the ICRS group ( p < 0.001 both). In the ICCR group, mean decrease in the pachymetry at the thinnest point of the cornea was 32.16 µm ( p = 0.01), and in the ICRS group, mean increase was 4.2 µm at 1 year ( p = 0.61). Conclusion: Intracorneal continuous ring 360° arc (ICCR) and intracorneal ring segment 340° (ICRS) are effective treatments for central keratoconus. No significant differences between rings were found on visual acuity, refraction, and keratometry improvement.

scholarly journals Miniaturized Wideband Loop Antenna Using a Multiple Half-Circular-Ring-Based Loop Structure and Horizontal Slits for Terrestrial DTV and UHD TV Applications

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 2916
Author(s):  
Junho Yeo ◽  
Jong-Ig Lee
Keyword(s):  
Coplanar Waveguide ◽  
Impedance Matching ◽  
Circular Ring ◽  
Loop Antenna ◽  
Digital Television ◽  
Loop Structure ◽  
High Definition ◽  
Circular Sector ◽  
Feed Line ◽  
Length Reduction

A miniaturized wideband loop antenna for terrestrial digital television (DTV) and ultra-high definition (UHD) TV applications is proposed. The original wideband loop antenna consists of a square loop, two circular sectors to connect the loop with central feed points, and a 75 ohm coplanar waveguide (CPW) feed line inserted in the lower circular sector. The straight side of the square loop is replaced with a multiple half-circular-ring-based loop structure. Horizontal slits are appended to the two circular sectors in order to further reduce the antenna size. A tapered CPW feed line is also employed in order to improve impedance matching. The experiment results show that the proposed miniaturized loop antenna operates in the 460.7–806.2 MHz frequency band for a voltage standing wave ratio less than two, which fully covers the DTV and UHD TV bands (470–771 MHz). The proposed miniaturized wideband loop antenna has a length reduction of 21.43%, compared to the original loop antenna.

scholarly journals Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Tobias Blanke ◽  
Markus Hagenkamp ◽  
Bernd Döring ◽  
Joachim Göttsche ◽  
Vitali Reger ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Circular Ring ◽  
Flow Conditions ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Pipe Radius

AbstractPrevious studies optimized the dimensions of coaxial heat exchangers using constant mass flow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar flow types. In contrast, in this study, flow conditions in the circular ring are kept constant (a set of fixed Reynolds numbers) during optimization. This approach ensures fixed flow conditions and prevents inappropriately high or low mass flow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic effort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass flow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefficients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy difference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy flux and hydraulic effort. The Reynolds number in the circular ring is instead of the mass flow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar flow and 60% for turbulent flow scenarios. Net-exergetic optimization shows a predominant influence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the flow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.

scholarly journals Magneto-Thermo-Structural Analysis of Power Transformers under Inrush and Short Circuit Conditions

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3266
Author(s):  
Antonio Roniel Marques de Sousa ◽  
Marcus Vinicius Alves Nunes ◽  
Wellington da Silva Fonseca ◽  
Ramon Cristian Fernandes Araujo ◽  
Diorge de Souza Lima
Keyword(s):  
Structural Analysis ◽  
Electric Power ◽  
Short Circuit ◽  
Real Data ◽  
Short Circuit Current ◽  
Power Transformers ◽  
Inrush Current ◽  
Electric Power Supply ◽  
Axial Forces ◽  
Radial Forces

The main equipment responsible for connection and transmission of electric power from generating centers to consumers are power transformers. This type of equipment is subject to various types of faults that can affect its components, in some cases also compromising its operation and, consequently, the electric power supply. Thus, in this paper, electromagnetic, thermal, and structural analysis of power transformers was carried out with the objective of providing the operator with information on the ideal moment for performing predictive maintenance, avoiding unplanned shutdowns. For this, computational simulations were performed using the finite element method (FEM) and, from that, the different transformer operation ways, nominal currents, inrush current, and short-circuit current were analyzed. In this perspective, analyses of the effects that thermal expansion, axial forces, and radial forces exerted were carried out, contributing to possible defects in this type of equipment. As a study object, simulations were carried out on a 50 MVA single-phase transformer. It is important to emphasize that the simulations were validated with real data of measurements and with results presented in the current literature.

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