Mode-locked fibre laser with e-controlled cavity length in ultra-wide range

2019 ◽  
Author(s):  
Alexey Ivanenko ◽  
Sergey M. Kobtsev ◽  
Boris Nyushkov ◽  
Kirill Serebrennikov ◽  
Denis Lutsenko
Keyword(s):  
Cavity Length ◽  
Fibre Laser ◽  
Wide Range

Force and Moment Measurements of Supercavitating Hydrofoils of Finite Span With Comparison to Theory

1975 ◽  
Vol 97 (4) ◽  
pp. 453-462
Author(s):  
P. Leehey ◽  
T. S. Stellinger
Keyword(s):  
Aspect Ratio ◽  
Asymptotic Expansions ◽  
Cavity Length ◽  
Large Aspect Ratio ◽  
Drag Coefficients ◽  
Finite Span ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Lift And Drag ◽  
Good Agreement

Measurements were made of lift, drag, and moment coefficients, and cavity length for aspect ratio 3 and 5 supercavitating hydrofoils of elliptical planform. These measurements are compared with theoretical predictions obtained from matching asymptotic expansions for large aspect ratio. Good agreement was obtained for lift and drag coefficients for angles of attack from 10 deg to 15 deg and for a wide range of cavity lengths. Theoretical moment coefficients were too large indicating the need for lifting surface corrections.

The Occurrence of Humping in Welding with Highest Beam Qualities

2007 ◽  
Vol 344 ◽  
pp. 731-743 ◽  
Author(s):  
Claus Thomy ◽  
Thomas Seefeld ◽  
Frank Vollertsen
Keyword(s):  
Three Dimensional ◽  
Welding Process ◽  
Single Mode ◽  
Fibre Laser ◽  
Experimental Investigations ◽  
Single Mode Fibre ◽  
Inviscid Incompressible Fluid ◽  
Wide Range ◽  
Welding Processes ◽  
Mode Fibre

The availability of lasers with highest beam qualities at laser powers of 1 kW (such as single-mode fibre laser, which nowadays come close to the theoretical limits) provides a unique tool to investigate welding process phenomena in a wide range of potential applications from welding with penetrations of some 50 "m to penetrations of some mm. Thus covering the field of micro welding as well as of macro welding, scalability of welding processes as well as size effects associated with the underlying physical phenomena may be of significance. In this paper, the humping effect will be given a closer look, as this periodic melt pool instability is an important limitation to possible welding speeds both in the micro and the macro range. Based on experimental investigations with a single-mode fibre laser (YLR-1000, laser power 1 kW, BPP < 0.4 mm*mrad), a model based on a modification of Rayleigh’s considerations on the stability of an inviscid incompressible fluid which is freely suspended in space and maintained only by surface tension is developed and discussed. It is shown that, within the scope of the investigations, humping to a large extent can be explained by Rayleigh’s theory, permitting to neglect the influence of three-dimensional melt flow.

Wide range of temperature and strain measurement using Bragg-grating-based fibre laser approach

2004 ◽  
Author(s):  
Jharna Mandal ◽  
Yonghang Shen ◽  
Suchandan Pal ◽  
Tong Sun ◽  
Kenneth T. Grattan ◽  
...  
Keyword(s):  
Strain Measurement ◽  
Fibre Laser ◽  
Bragg Grating ◽  
Wide Range

Rotordynamic Forces Acting on Three-Bladed Inducer Under Super-Synchronous/Synchronous Rotating Cavitation

2008 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Masato Eguchi ◽  
Taiichi Motomura ◽  
Masaharu Uchiumi ◽  
Hirotaka Kure ◽  
...  
Keyword(s):  
Cavity Length ◽  
Active Magnetic Bearings ◽  
Fluid Forces ◽  
Wide Range ◽  
Cavitation Instability ◽  
Cryogenic Flow ◽  
Shaft Vibration ◽  
Rotordynamic Forces ◽  
Relationship Of ◽  
The Relationship

Asymmetric cavitation, in which cavity lengths are unequal on each blade, is known as a source of cavitation induced shaft vibration in turbomachinery. To investigate the relationship of the uneven cavity length and rotordynamic force in a cavitating inducer with three blades, we conducted two experiments. In one, the growth of cavity unevenness at the inception of synchronous rotating cavitation in cryogenic flow was observed, and in the other, the rotordynamic fluid forces in water were examined by using a rotordynamic test stand with active magnetic bearings. Rotordynamic performances were obtained within a wide range of cavitation numbers and whirl/shaft speed ratios included super-synchronous/synchronous rotating cavitation. These experimental results indicate that the shaft vibration due to the rotating cavitation is one type of self-excited vibrations arising from the coupling of cavitation instability and rotordynamics.

Rotordynamic Forces Acting on Three-Bladed Inducer Under Supersynchronous/Synchronous Rotating Cavitation

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Yoshiki Yoshida ◽  
Masato Eguchi ◽  
Taiichi Motomura ◽  
Masaharu Uchiumi ◽  
Hirotaka Kure ◽  
...  
Keyword(s):  
Cavity Length ◽  
Active Magnetic Bearings ◽  
Fluid Forces ◽  
Wide Range ◽  
Cavitation Instability ◽  
Cryogenic Flow ◽  
Shaft Vibration ◽  
Rotordynamic Forces ◽  
Relationship Of ◽  
The Relationship

Asymmetric cavitation, in which cavity lengths are unequal on each blade, is known as a source of cavitation induced shaft vibration in turbomachinery. To investigate the relationship of the uneven cavity length and rotordynamic force in a cavitating inducer with three blades, we conducted two experiments. In one, the growth of cavity unevenness at the inception of synchronous rotating cavitation in cryogenic flow was observed, and in the other, the rotordynamic fluid forces in water were examined by using a rotordynamic test stand with active magnetic bearings. Rotordynamic performances were obtained within a wide range of cavitation numbers, and whirl/shaft speed ratios included supersynchronous/synchronous rotating cavitation. These experimental results indicate that the shaft vibration due to the rotating cavitation is one type of self-excited vibrations arising from the coupling of cavitation instability and rotordynamics.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

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