scholarly journals On the Dynamics of the LAGEOS-I Spin Vector: High Precision Direct Observations and Comparisons to Theoretical Modeling

1997 ◽  
Vol 165 ◽  
pp. 341-346
Author(s):  
D. Currie ◽  
K. Kissell ◽  
P. Avizonis ◽  
D. Wellnitz
Keyword(s):  
Short Pulse ◽  
Laser Ranging ◽  
Accurate Information ◽  
Spin Vector ◽  
Spin Motion ◽  
Crustal Motion ◽  
Orbital Parameters ◽  
Short Pulse Laser ◽  
Direct Observations ◽  
Gyroscopic Effects

AbstractLAGEOS I is a high-density geodetic satellite launched by NASA on 4 May 1976 (Johnson et al., 1976). Using a network of laser ranging stations, GSFC/NASA has maintained extremely accurate information on the orbital motions of LAGEOS I, and the later LAGEOS II and on the time-dependent evolution of their orbital parameters. The development of short-pulse laser ranging systems, and better models for atmospheric refractive effects, have dramatically improved the ability to locate the spacecraft or measure geodetic position and terrestrial crustal motion, but these systems do not measure the satellite rotational motion or gyroscopic effects, thought initially unimportant. Primarily as a result of technical strides in orbit determination, it is now recognized that the spin-motion is critical to understanding weak but important interactions with the environment.

Silicon Thinning using Ultra-Short Pulse Laser Ablation

2004 ◽  
Author(s):  
F. Beaudoin ◽  
P. Perdu ◽  
C. DeNardi ◽  
R. Desplats ◽  
J. Lopez ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Sample Preparation ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Special Care ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser

Abstract Ultra-short pulse laser ablation is applied to IC backside sample preparation. It is contact-less, non-thermal, precise and can ablate the various types of material present in IC packages. This study concerns the optimization of ultra-short pulse laser ablation for silicon thinning. Uncontrolled silicon roughness and poor uniformity of the laser thinned cavity needed to be tackled. Special care is taken to minimize the silicon RMS roughness to less than 1µm. Application to sample preparation of 256Mbit devices is presented.

Chromium oxide dissolution in steels via short pulse laser processing

2013 ◽  
Vol 115 (4) ◽  
pp. 1469-1477 ◽  
Author(s):  
Evgeny Kharanzhevskiy ◽  
Sergey Reshetnikov
Keyword(s):  
Pulse Laser ◽  
Chromium Oxide ◽  
Laser Processing ◽  
Short Pulse ◽  
Oxide Dissolution ◽  
Short Pulse Laser

scholarly journals Experimental study of lateral resistance of bolted joints using Japanese cedar (Cryptomeria japonica) treated with resin impregnation

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Keita Ogawa ◽  
Satoshi Fukuta ◽  
Kenji Kobayashi
Keyword(s):  
Short Pulse ◽  
Japanese Cedar ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Yield Load ◽  
Short Pulse Laser ◽  
Resin Impregnation ◽  
Lateral Resistance ◽  
Ultraviolet Wavelength ◽  
Resistance Performance

Abstract The development of wooden joints possessing high resistance performance has become an important issue for the construction of newer buildings. This study attempts to strengthen the lateral resistance of bolted joints using the previously reported plasticizing technique. This technique consists of two processing stages: incising the surface of the wood using an ultraviolet wavelength short-pulse laser and impregnating the resin into the incised area. This technique makes it possible to plasticize only a local part of the wood surface. Bolted joint specimens were assembled using plasticized wood around the bolt hole, and the lateral tests were conducted. Acrylic monomer and urethane prepolymer were used as the impregnating resins and their incision depths were set as 4 and 10 mm. When the lateral load acted parallel to the grain, changes in the lateral resistance characteristics were observed, especially for the stiffness and yield load. For example, when acryl was used, and the incision depth was 10 mm, an increment of 73% in the yield load was observed, as compared to the non-impregnated specimens. The specimen groups impregnated with acryl exhibited greater changes in their properties than those using urethane. When loaded perpendicular to the grain, an increase in properties were observed; however, these increments were lower than those of the groups loaded parallel to the grain.

scholarly journals Machine learning for multi-dimensional optimisation and predictive visualisation of laser machining

2021 ◽  
Author(s):  
Michael D. T. McDonnell ◽  
Daniel Arnaldo ◽  
Etienne Pelletier ◽  
James A. Grant-Jacob ◽  
Matthew Praeger ◽  
...  
Keyword(s):  
Short Pulse ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Laser Machining ◽  
Laser Materials ◽  
Parameter Optimisation ◽  
Short Pulse Laser ◽  
Alternative Approach ◽  
Highly Nonlinear ◽  
Wide Range

AbstractInteractions between light and matter during short-pulse laser materials processing are highly nonlinear, and hence acutely sensitive to laser parameters such as the pulse energy, repetition rate, and number of pulses used. Due to this complexity, simulation approaches based on calculation of the underlying physical principles can often only provide a qualitative understanding of the inter-relationships between these parameters. An alternative approach such as parameter optimisation, often requires a systematic and hence time-consuming experimental exploration over the available parameter space. Here, we apply neural networks for parameter optimisation and for predictive visualisation of expected outcomes in laser surface texturing with blind vias for tribology control applications. Critically, this method greatly reduces the amount of experimental laser machining data that is needed and associated development time, without negatively impacting accuracy or performance. The techniques presented here could be applied in a wide range of fields and have the potential to significantly reduce the time, and the costs associated with laser process optimisation.

The study of time dependent, broadband X-ray emission from ultra-short pulse laser produced plasmas

1994 ◽  
Author(s):  
Ronnie Shepherd ◽  
Rex Booth ◽  
Dwight Price ◽  
Rosemary Walling ◽  
Richard More ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Short Pulse ◽  
Time Dependent ◽  
X Ray ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser

scholarly journals A New Formalism for Classifying Spin-Orbit Systems Using Tools Distilled from the Theory of Bundles

2016 ◽  
Vol 40 ◽  
pp. 1660098
Author(s):  
K. Heinemann ◽  
D. P. Barber ◽  
J. A. Ellison ◽  
M. Vogt
Keyword(s):  
Normal Form ◽  
Spin Dynamics ◽  
Invariant Sets ◽  
Spin Orbit ◽  
Spin Tensor ◽  
Spin Vector ◽  
Spin Motion ◽  
New Formalism ◽  
Fibre Bundles ◽  
Ongoing Work

We give an informal summary of ongoing work which uses tools distilled from the theory of fibre bundles to classify and connect invariant fields associated with spin motion in storage rings. We mention four major theorems. One ties invariant fields with the notion of normal form, the second allows comparison of different invariant fields and the two others tie the existence of invariant fields to the existence of certain invariant sets. We explain how the theorems apply to the spin dynamics of spin-[Formula: see text] and spin-[Formula: see text] particles. Our approach elegantly unifies the spin-vector dynamics from the T-BMT equation with the spin-tensor dynamics and other dynamics and suggests an avenue for addressing the question of the existence of the invariant spin field.

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