scholarly journals INVOLVEMENT OF ALTIMETRY INFORMATION INTO THE IMPROVED PHOTOCLINOMETRY METHOD FOR RELIEF RETRIEVAL FROM A SLOPE FIELD

2021 ◽  
Vol 26 (2) ◽  
pp. 173-188
Author(s):  
Yu. V. Kornienko ◽  
◽  
I. A. Dulova ◽  
N. V. Bondarenko ◽  
◽  
...  
Keyword(s):  
Computer Simulation ◽  
Surface Area ◽  
Surface Relief ◽  
Beam Pattern ◽  
Altimeter Data ◽  
Altimetry Data ◽  
Narrow Beam ◽  
Wide Beam ◽  
Planet Surface ◽  
Lunar Reconnaissance Orbiter

Purpose: The paper discusses the possibility for increasing the planet’s surface relief retrieving accuracy with the improved photoclinometry method through the reference of the desired relief to the altimetry data. The general approach to solving the problem is proposed. The use of altimeters having both wide and narrow beam patterns are discussed, but the narrow beam pattern altimeter data is studied more in detail. The spatial resolution of the retrieved relief calculated with the improved photoclinometry method conforms to the one of the source images. Altimetry allows absolute reference to the surface heights and improves the accuracy of the relief determination. Design/metodology/approach: The work is based on the improved photoclinometry method for the planet’s surface relief retrieving from images. This method is mathematically rigorous and uses the Bayesian statistical approach, that allows calculation of the most probable relief according to available observations. Findings: An approach to determining the optimal statistical estimate of the surface heights from images in the frames of the improved photoclinometry method is proposed and an expression for the optimal filter which converts source images along with the wide beam pattern altimetry data into the most probable relief of the planet surface area is presented. The reference technique for the narrow beam pattern altimeter data is formulated. The efficiency of the method has been verified with the computer simulation. The relief of the surface area in Mare Imbrium on the Moon was retrieved using three images and laser altimeter data taken by the “Lunar Reconnaissance Orbiter” spacecraft. Conclusions: Accounting for the narrow beam pattern altimeter data increases the accuracy of the relief determination. Using the narrow beam pattern altimeter data turns out to be more preferable over the involving wide beam pattern altimeter data. Computer simulation has shown that accounting for the narrow beam pattern altimeter data significantly increases the accuracy of the calculated heights as against using images exclusively and helps to speed up the calculation procedure. Key words: planet surface relief; photometry; altimetry; optimal filtering; statistical estimation of random value

scholarly journals An Improved Digital Elevation Model of the Lunar Mons Rümker Region Based on Multisource Altimeter Data

2018 ◽  
Vol 10 (9) ◽  
pp. 1442 ◽  
Author(s):  
Fei Li ◽  
Chang Zhu ◽  
Weifeng Hao ◽  
Jianguo Yan ◽  
Mao Ye ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Ground Truth ◽  
Horizontal Resolution ◽  
Altimeter Data ◽  
Laser Altimeter ◽  
Lunar Landing ◽  
Data Processing Method ◽  
Digital Elevation ◽  
Lunar Reconnaissance Orbiter ◽  
Elevation Model

Mons Rümker is the primary candidate region for the lunar landing mission of Chang’E-5. We propose a data processing method that combines multisource altimeter data and we developed an improved digital elevation model (DEM) of the Mons Rümker region with a horizontal resolution of 256 pixels per degree. The lunar orbiter laser altimeter (LOLA) onboard the lunar reconnaissance orbiter (LRO) acquired 884 valid orbital benchmark data with a high precision. A special crossover adjustment of 156 orbital profiles from the Chang’E-1 laser altimeter (LAM) and 149 orbital profiles from the SELenological and ENgineering Explorer (SELENE) laser altimeter (LALT) was applied. The radial residual root mean square (RMS) of the LAM was reduced from 154.83 ± 43.60 m to 14.29 ± 27.84 m and that of the LALT was decreased from 3.50 ± 5.0 m to 2.75 ± 4.4 m. We used the adjusted LAM and LALT data to fill the LOLA gaps and created the merged LOLA + LAM and LOLA + LALT DEMs. The merged LOLA + LAM DEM showed distortions because of the horizontal geolocation errors in the LAM data. The merged LOLA + LALT DEM was closer to the ground truth than the LOLA-only DEM when validated with the images of the LRO camera (LROC).

Observing Sea Level Changes Using Satellite Altimetry and In Situ Data

2020 ◽  
Author(s):  
Nikos Flokos ◽  
Maria Tsakiri
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Zone ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Altimeter Data ◽  
Atmospheric Effects ◽  
Data Sets ◽  
Altimetry Data

<p>corresponding author: N.Flokos</p><p>[email protected]</p><p>ABSTRACT</p><p>Sea level change is one of the key indicators of climate change with numerous effects such as flooding, erosion of beaches, salt intrusion.  The detailed global picture of sea level and the monitoring of its spatial-temporal changes is performed by Satellite Altimetry (SA). Nowadays, SA data compare well with measurements from the global tide gauge network, but the aim of 0.3 mm/year accuracy in the altimeter derived rate of global mean sea level rise is still not fully met. </p><p>Whilst the precise determination of global and regional sea level rise from SA data is promising, there is however an observational gap in our knowledge regarding the coastal zone. While Tide Gauges (TG) are usually located at the coast, therefore providing coastal sea level measurements, altimeters have difficulties there. Filling this gap becomes important when considering that the impact of sea level rise can be devastating on the coast with effects on society and ecosystems. This makes it even more significant knowing that there are many stretches of the world’s coast that still do not possess in situ level measuring devices.  </p><p>This work aims to discuss the available data and methods that link the SA measurements of sea level rise with TG measurements. Whilst there is rich literature on relevant applications, it is important to have a clear and concise methodology on this.</p><p>Tide gauge data</p><p>Several post processing steps need to be applied to the raw TG data to enrich the raw Sea Surface Heights (SSH) values and make them comparable with SA data. There are several geophysical corrections, such as pressure and wind effects, which can be applied to TG data in order to deduce  Sea Level (SL) and be consistent with altimeter data. High frequency atmospheric effects on TG data are corrected using the Dynamic Atmospheric Correction (DAC) provided by AVISO. One other large uncertainty is the vertical stability of the TG benchmark over time. TG data must be corrected for the Vertical Land Motion (VLM) to enable the comparison of two sea level measurements (TG and SA) and their later integration within the surfaces of the absolute sea heights. The main VLM dataset can be obtained from SONEL database (SONEL 2016) which provides crustal velocities from the continuous GNSS measurements at sites collocated to the TG.</p><p>Satellite altimetry data</p><p>Whilst Satellite Altimetry over the open ocean is a mature discipline, global altimetry data collected over the coastal ocean remain still largely unexploited. This is because of intrinsic difficulties in the corrections and issues of land contamination in the footprint that have so far resulted in systematic flagging and rejection of these data. In this work, the relevant methodology to overcome these problems and extend the capabilities of current and future altimeters to the coastal zone (coastal altimetry) will be discussed and a number of coastal altimetry data sets will be used (eg SARvatore, X-TRACK, RADS etc). Finally, a practical example using real data sets over the Aegean Sea will be presented. </p><p> </p><p> </p>

Changes in the Structure of Steel during Quenching in a Magnetic Field

2020 ◽  
Vol 989 ◽  
pp. 79-84 ◽  
Author(s):  
Viktor N. Pustovoit ◽  
Yuri V. Dolgachev ◽  
L.P. Aref'eva
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Martensitic Transformation ◽  
Specific Surface ◽  
Surface Area ◽  
Constant Magnetic Field ◽  
Surface Relief ◽  
Volumetric Strain ◽  
Transformation Products ◽  
Electron Microscopes

The structure of martensite obtained by quenching steel under the action of a constant magnetic field was studied. The kinetic changes of the martensitic transformation, caused by the action of a magnetic field, are expressed in the structure by an increase in the dispersity of the transformation products. Samples of steels C45, 100CrMn6 and 30HGSA were investigated. Dispersity was evaluated statistically in images obtained on light and electron microscopes. The specific surface area was measured and the parameters of the surface relief caused by martensitic transformation were studied. Experimental data show that after quenching in a magnetic field, a decrease in the volumetric strain of the transformation, an increase in the dispersity of packets of martensitic crystals and components of the packets are observed. It is concluded that an increase in dispersion and a fragmentation of the structure of martensite are mainly the result of multiplicative nucleation.

Social Facilitation of Young Children's Dynamic Balance Performance

1985 ◽  
Vol 7 (2) ◽  
pp. 150-165 ◽  
Author(s):  
Mary Jo MacCracken ◽  
Robert E. Stadulis
Keyword(s):  
Social Facilitation ◽  
Dynamic Balance ◽  
Narrow Beam ◽  
Balance Performance ◽  
Social Situations ◽  
Age And Gender ◽  
Wide Beam ◽  
Positive Effects ◽  
Balance Task ◽  
And Gender

Dynamic balance performance of young children (ages 4, 6, and 8) was assessed in three social situations: alone (only with tester present); coaction (one other child performing at the same time); and spectators (five other observer children present). Within each age and gender, children (N = 120) were classified as of higher or lower comparative skill. Each balance task performed (walking forward and backward on a line, a narrow beam or a wide beam) was classified as representing easier or more difficult tasks for each child individually. Findings (p ≤ .05) indicated that the facilitation effects of social situations strengthened over age, with spectators producing increments in performance for children of higher skill (especially boys) and decrements in performance for the lower skilled children (both boys and girls). Coaction resulted in positive effects regardless of skill level.

Multifrequency and Nonuniformly-Spaced Arrays: Effects on Grating Lobe Amplitude

1982 ◽  
Vol 4 (4) ◽  
pp. 351-354
Author(s):  
B. G. Bardsley ◽  
D. A. Christensen ◽  
T. A. Pryor
Keyword(s):  
Computer Simulation ◽  
Simulation Study ◽  
Ultrasonic Transducer ◽  
Side Lobe ◽  
Beam Pattern ◽  
Periodic Array ◽  
Main Lobe ◽  
Computer Simulation Study ◽  
Grating Lobe ◽  
Transducer Arrays

A computer simulation study on the effects of multifrequency and aperiodic ultrasonic transducer arrays has shown that both methods improve grating lobe response when compared to a periodic array of the same aperture and element spacing. The multifrequency array produces a better beam pattern than either the aperiodic or combination aperiodic/multifrequency array. Both the aperiodic and multifrequency arrays have a narrower main lobe and higher side lobe response than a periodic array with reduced element spacing and an equal number of elements.

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