High-Accuracy Mars Approach Navigation with Radio Metric and Optical Data

1990 ◽  
Author(s):  
ALEX KNOPLIV ◽  
LINCOLN J. WOOD
Keyword(s):  
High Accuracy ◽  
Optical Data

scholarly journals Analyses of celestial pole offsets with VLBI, LLR, and optical observations

2019 ◽  
Vol 627 ◽  
pp. A81
Author(s):  
Y.-T. Cheng ◽  
J.-C. Liu ◽  
Z. Zhu
Keyword(s):  
High Accuracy ◽  
Least Square ◽  
Linear Term ◽  
Optical Observations ◽  
Optical Data ◽  
Quadratic Model ◽  
Lunar Laser Ranging ◽  
Long Period ◽  
The Earth ◽  
Celestial Pole

Aims. This work aims to explore the possibilities of determining the long-period part of the precession-nutation of the Earth with techniques other than very long baseline interferometry (VLBI). Lunar laser ranging (LLR) is chosen for its relatively high accuracy and long period. Results of previous studies could be updated using the latest data with generally higher quality, which would also add ten years to the total time span. Historical optical data are also analyzed for their rather long time-coverage to determine whether it is possible to improve the current Earth precession-nutation model. Methods. Celestial pole offsets (CPO) series were obtained from LLR and optical observations and were analyzed separately by weighted least-square fits of three empirical models, including a quadratic model, a linear term plus an 18.6-year nutation term, and a linear term plus two nutation terms with 18.6-year and 9.3-year periods. Joint analyses of VLBI and LLR data is also presented for further discussion. Results. We improved th determination of the nutation terms with both VLBI and LLR data. The VLBI data present a most reliable feature of the CPO series with the highest accuracy, and they are most important for determining the precession-nutation of the Earth. The standard errors of CPO obtained from the LLR technique have reached a level of several tens of microarcseconds after 2007, but they are probably underestimated because the models used in the calculation procedure are not perfect. Nevertheless, the poor time resolution of LLR CPO series is also a disadvantage. However, this indicates that LLR has the potential to determine celestial pole offsets with a comparably high accuracy with VLBI in the future and to serve as an independent check for the VLBI results. The current situation of LLR observations is also analyzed to provide suggestions of future improvement. The typical standard error of CPO series from historic optical observations is about two hundred times larger than that of the VLBI series and can therefore hardly contribute to the contemporary precession-nutation theory.

Fabrication of High-Accuracy Microtranslation Table for Near-Field Optical Data Storage Actuated by Inverted Scratch-Drive Actuators

2003 ◽  
Vol 42 (Part 1, No. 6B) ◽  
pp. 4074-4078 ◽  
Author(s):  
Yoshiaki Kanamori ◽  
Hiroto Yahagi ◽  
Takahito Ono ◽  
Minoru Sasaki ◽  
Kazuhiro Hane
Keyword(s):  
Data Storage ◽  
Near Field ◽  
High Accuracy ◽  
Optical Data Storage ◽  
Optical Data

A New 1,000 kV Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 260-261
Author(s):  
M. Nishigaki ◽  
S. Katagiri ◽  
H. Kimura ◽  
B. Tadano
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Basic Research ◽  
Chromatic Aberration ◽  
High Accuracy ◽  
Biological Specimen ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron

The high voltage electron microscope has many advantageous features in comparison with the ordinary electron microscope. They are a higher penetrating efficiency of the electron, low chromatic aberration, high accuracy of the selected area diffraction and so on. Thus, the high voltage electron microscope becomes an indispensable instrument for the metallurgical, polymer and biological specimen studies. The application of the instrument involves today not only basic research but routine survey in the various fields. Particularly for the latter purpose, the performance, maintenance and reliability of the microscope should be same as those of commercial ones. The authors completed a 500 kV electron microscope in 1964 and a 1,000 kV one in 1966 taking these points into consideration. The construction of our 1,000 kV electron microscope is described below.

The spindle stage: A powerful optical tool

1988 ◽  
Vol 46 ◽  
pp. 52-53
Author(s):  
Mickey E. Gunter ◽  
F. Donald Bloss
Keyword(s):  
Significant Error ◽  
Optical Data ◽  
Refractive Indices ◽  
Axis Of Rotation ◽  
Polarizing Microscope ◽  
Microscope Stage

A single, reasonably homogeneous, nonopaque 30-to-300 μm crystal, mounted on a spindle stage and studied by immersion methods under a polarizing microscope, yields optical data frequently sufficient to identify and characterize a substance unequivocally. The data obtainable include (1) the orientation of the crystal's principal vibration axes and (2) its principal refractive indices, to within 0.0002 if desired, for light vibrating along these principal vibration axes. Spindle stages tend to be simple and relatively inexpensive, some costing less than $50. They permit rotation of the crystal about a single axis which is parallel to the microscope stage. This spindle or S-axis is thus perpendicular to the M-axis, namely the microscope stage's axis of rotation.A spindle stage excels when studying anisotropic crystals. It orients uniaxial crystals within minutes and biaxial crystals almost as quickly so that their principal refractive indices - ɛ and ω (uniaxial); α, β and γ (biaxial) - can be determined without significant error from crystal misorientation.

Application Of BIM-Technology In The Restoration Of Buildings

2020 ◽  
pp. 42-48
Keyword(s):  
Chinese Communist Party ◽  
Laser Scanning ◽  
High Accuracy ◽  
Information Environment ◽  
Information Modeling ◽  
Structural Scheme ◽  
Traditional Design ◽  
Information Interaction ◽  
Heritage Buildings ◽  
Effective Organization

The paper describes the main trends in the development of BIM technologies in the field of restoration and reconstruction of historical and cultural heritage buildings. The practical part of the paper presents the experience in using information modeling technologies when restoring the building, where the VI Congress of the Chinese Communist Party in Moscow took place. The use of laser scanning technologies made it possible to reproduce with high accuracy in the information model the original appearance of the building using Autodesk RevitR software. It is shown, how the use of information modeling technologies affects the duration of restoration process, taking into account the calculation of the structural scheme and bearing structures of the building, ensuring the identity of the decoration and the effective organization of electromechanical installation. Operating in a single BIM information environment makes it possible to continuously obtain reliable information on the project, which provides more effective information interaction and communication of participants compared to using traditional design methods.

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