Résonateur ouvert en géométrie sphérique

1980 ◽  
Vol 58 (1) ◽  
pp. 80-86 ◽  
Author(s):  
Gilles Duret ◽  
Gérard Zepp ◽  
Alain Wick
Keyword(s):  
Radius Of Curvature ◽  
Large Radius ◽  
Open Resonators

Most of the approximate theories of the spherical open resonators are insufficient, except for the very large radius of curvature. It is often necessary to consider other cases. The theory we have developed is applicable for any curvature and aperture of the mirrors. This theory also allows study of multi-dielectric cavities. This method is accurately studied in detail in this paper.

Duplex Spread Blade Method for Cutting Hypoid Gears with Modified Tooth Surface

1998 ◽  
Vol 120 (3) ◽  
pp. 441-447 ◽  
Author(s):  
K. Kawasaki ◽  
H. Tamura
Keyword(s):  
Cutting Edge ◽  
Tooth Surface ◽  
Radius Of Curvature ◽  
Large Radius ◽  
Ring Gear ◽  
Circular Arc ◽  
Hypoid Gears ◽  
Manufacturing Method ◽  
Straight Line

In this paper, a duplex spread blade method for cutting hypoid gears with modified tooth surface is proposed. The duplex spread blade method provides a rapid and economical manufacturing method because both the ring gear and pinion are cut by a spread blade method. In the proposed method, the nongenerated ring gear is manufactured with cutting edge that is altered from the usual straight line to a circular arc with a large radius of curvature and the circular arc cutting edge produces a modified tooth surface. The pinion is generated by a cutter with straight cutting edges as usual. The main procedure of this method is the determination of the cutter specifications and machine settings. The proposed method was validated by gear manufacture.

Experimental and Computational Investigation of Shaped Film Cooling Holes Designed to Minimize Inlet Separation

2020 ◽  
Author(s):  
Fraser B. Jones ◽  
Dale W. Fox ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Velocity Ratio ◽  
Tangential Velocity ◽  
Velocity Fields ◽  
Radius Of Curvature ◽  
Large Radius ◽  
Combustion Gases ◽  
Shaped Hole ◽  
Manufacturing Technologies ◽  
Film Cooling Holes

Abstract Film cooling is used to protect turbine components from the extreme temperatures by ejecting coolant through arrays of holes to create an air buffer from the hot combustion gases. Limitations in traditional machining meant film cooling holes universally have sharp inlets which create separation regions at the hole entrance. The present study uses experimental and computational data to show that these inlet separation are a major cause of performance variation in crossflow fed film cooling holes. Three hole designs were experimentally tested by independently varying the coolant velocity ratio (VR) and the coolant channel velocitty ratio (VRc) to isolate the effects of crossflow on hole performance. Leveraging additive manufacturing technologies, the addition of a 0.25D radius fillet to the inlet of a 7-7-7 shaped hole is shown to significantly improve diffuser usage and significantly reduce variation in performance with VRc. A second AM design used a very large radius of curvature inlet to reduce biasing caused by the inlet crossflow. Experiments showed that this “swept” hole design did minimize biasing of coolant flow to one side of the shaped hole and it significantly reduced variations due to varying VRc. RANS simulations at six VR and three VRc conditions were made for each geometry to better understand how the new geometries changed the velocity field within the hole. The sharp and rounded inlets were seen to have very similar tangential velocity fields and jet biasing. Both AM inlets created more uniform, slower velocity fields entering the diffuser. The results of this paper indicate large improvements in film cooling performance can be found by leveraging AM technology.

A Numerical Analysis on the Dissimilar Channel Angular Pressing Process by Rolling

2005 ◽  
Vol 475-479 ◽  
pp. 3231-3234 ◽  
Author(s):  
Moo Young Huh ◽  
Hyoung Jin Choi ◽  
J.H. Ok ◽  
Beong Bok Hwang ◽  
Bok Choon Kang
Keyword(s):  
Strain State ◽  
Model Material ◽  
Radius Of Curvature ◽  
Strain Component ◽  
Large Radius ◽  
Rigid Plastic ◽  
Center Layer ◽  
Angular Pressing ◽  
Dimensional Finite Element ◽  
Deformation Mechanics

The dissimilar channel angular pressing (DCAP) process by rolling was numerically modeled and analyzed by the rigid-plastic two-dimensional finite element method in order to optimize the strain state of the DCAP process. Three distinct deformation mechanics during DCAP by rolling includes rolling, bending, and shearing. AA 1100 aluminum alloy was selected as a model material for the analysis of DCAP process. Difference in the friction conditions between the upper and lower roll surfaces led to large variation of shear strain component throughout the thickness of sample. Strain accompanying bending turned out to be negligible because of a large radius of curvature by relatively large roll diameter. The concentrated shear deformation was monitored at the corner of the DCAP-channel where the abrupt change in the direction of material flow occurred. The strain state at the upper and lower surfaces was observed to vary strongly from that of the center layer of the sheet.

G203 Aerodynamic Sound Generated by Bend Round Bars with Large Radius of Curvature

2007 ◽  
Vol 2007 (0) ◽  
pp. _G203-1_-_G203-4_
Author(s):  
Hiroki MATSUMOTO ◽  
Ken-ichi SAITOH ◽  
Tetsuya YOSHIDA
Keyword(s):  
Radius Of Curvature ◽  
Large Radius ◽  
Aerodynamic Sound

Depth‐focusing analysis using a wavefront‐curvature criterion

Geophysics ◽  
1993 ◽  
Vol 58 (8) ◽  
pp. 1148-1156 ◽  
Author(s):  
Scott MacKay ◽  
Ray Abma
Keyword(s):  
Seismic Energy ◽  
Radius Of Curvature ◽  
Large Radius ◽  
Data Set ◽  
Depth Migration ◽  
Amplitude Data ◽  
Zero Radius ◽  
Inverse Radius ◽  
Interpretation Process ◽  
Zero Offset

Depth‐focusing analysis (DFA), a method of refining velocities for prestack depth migration, relies on amplitude buildups at zero offset to determine the extrapolation depths that best focus the migrated data. Unfortunately, seismic energy from dipping interfaces, diffractions, and noise often produce spurious amplitude indications of focusing. To reduce possible ambiguity in the DFA interpretation process, we introduce a new attribute for determining focusing that is relatively independent of amplitude. Our approach is based on estimates of the radius of wavefront curvature. The estimates are derived from normal moveout analysis of nonzero‐offset data saved during migration. By relating steeper moveout to smaller radius of wavefront curvature, focusing is defined by a wavefront curvature of zero radius. Additionally, we show that applying inverse‐radius weights to the amplitude data attenuates nonfocused events due to their large radius of curvature. Using the Marmousi data set, our weighting scheme resulted in reduced spurious focusing and enhanced velocity resolution in DFA.

scholarly journals COMPARATIVE ANALYSIS OF MAMMALIAN SPERM MOTILITY

1972 ◽  
Vol 53 (2) ◽  
pp. 561-573 ◽  
Author(s):  
David M. Phillips
Keyword(s):  
High Speed ◽  
Mammalian Species ◽  
Chinese Hamster ◽  
Small Radius ◽  
Radius Of Curvature ◽  
Large Radius ◽  
Cross Sectional ◽  
Mammalian Sperm ◽  
High Speed Cinematography ◽  
Pass Through

Spermatozoa of several mammalian species were studied by means of high-speed cinematography and electron microscopy. Three types of motile patterns were observed in mouse spermatozoa. The first type involved an asymmetrical beat which seemed to propel the sperm in circular paths. The second type involved rotation of the sperm and appeared to allow them to maintain straight paths. In the third type of pattern, the sperm appeared to move by crawling on surfaces in a snakelike manner. Spermatozoa of rabbit and Chinese hamster also had an asymmetrical beat which sometimes caused them to swim in circles. In spite of the asymmetry of the beat, these spermatozoa were also able to swim in straight paths by rotating around a central axis as they swam. Spermatozoa of some species appeared very flexible; their flagella formed arcs with a very small radius of curvature as they beat. Spermatozoa of other species appeared very stiff, and their flagella formed arcs with a very large radius of curvature. The stiffness of the spermatozoan appeared to correlate positively with the cross-sectional area of the dense fibers. This suggests that the dense fibers may be stiff elastic elements. Opossum sperm become paired as they pass through the epididymis. Pairs of opossum spermatozoa beat in a coordinated, alternating manner.

Sign in / Sign up

Export Citation Format

Share Document