scholarly journals PERFORMANCE ANALYSIS OF LATVIAN ZENITH CAMERA

2018 ◽  
Vol 44 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Ansis ZARIŅŠ ◽  
Augusts RUBANS ◽  
Gunārs SILABRIEDIS
Keyword(s):  
Performance Analysis ◽  
Data Reduction ◽  
Field Observations ◽  
Reference Star ◽  
Vertical Deflection ◽  
Error Sources ◽  
Star Catalog ◽  
The University ◽  
Astrometric Data ◽  
Observation Results

Since finalizing of design in 2016, the digital zenith camera of the University of Latvia was involved in a number of test observations as well as field observations at about 70 different sites. The paper presents analysis of observation results, estimation of instrument’s performance and accuracy. Random and systematic error sources are outlined. Impact of anomalous refraction on vertical deflection determination is discussed. Results of adaptation of GAIA reference star catalog for astrometric data reduction are reported.

The digital zenith camera as an additional technique for quasi-geoid model determination of Latvia

2020 ◽  
Author(s):  
Katerina Morozova ◽  
Gunars Silabriedis ◽  
Ansis Zarins ◽  
Janis Balodis ◽  
Reiner Jaeger
Keyword(s):  
Geological Structure ◽  
Geopotential Model ◽  
Parametric Modelling ◽  
Vertical Deflection ◽  
Geoid Model ◽  
Star Catalog ◽  
Geopotential Models ◽  
Model Determination ◽  
The University

<p>The digital zenith camera VESTA (VErtical by STArs) was designed by the Institute of Geodesy and Geoinformatics (GGI) of the University of Latvia and completed in 2016. By 2020 more than 400 terrestrial vertical deflection measurements were observed in the territory of Latvia. These observations were post-processed by the GGI developed software and the accuracy was evaluated at 0.1 arc seconds. In 2019 two new cameras have been developed, which will be used in future projects, e.g., in determination of properties of local geological structure or Earth crust movement monitoring. Measurement control software corrections and complements, data processing improvements and automation and transition to GAIA data release 2 star catalog were done. The accuracy of the measurements of improved camera was evaluated at 0.05 arc seconds.</p><p>Terrestrial vertical deflection observations were compared with global geopotential models, e.g. GGM+ and EGM2008. The results show a better correspondence with GGM+ model by evaluating the standard deviation: 0.314 and 0.307 arc seconds for ξ and η components respectively in comparison to 0.346 and 0.358 arc seconds for ξ and η components for EGM2008 model. The comparisons of average and minimum/maximum differences are introduced in this study for better evaluation of the results. Moreover, vertical deflections have been used as additional terrestrial data in DFHRS (Digital Finite-element Height Reference Surface) software v. 4.3 in combination with GNSS/levelling data (B, L, hH) and global geopotential model EGM2008 for gravity field and quasi-geoid improvement (www.dfhbf.de). This approach is based on parametric modelling and computation of height reference surfaces (HRS) from geometric and physical observation components in a hybrid adjustment approach. The results of the computed quasi-geoid models using different types of data are introduced in this research, representing several solutions, as well as these solutions are compared with the national quasi-geoid model LV’14.</p>

scholarly journals CPC2 Reduction with Hipparcos and Proper Motions in The Southern Hemisphere

1998 ◽  
Vol 11 (1) ◽  
pp. 551-551
Author(s):  
N. Zacharias ◽  
M.I. Zacharias ◽  
C. de Vegt ◽  
C.A. Murray
Keyword(s):  
Southern Hemisphere ◽  
Systematic Errors ◽  
Reference Star ◽  
Proper Motions ◽  
Positional Accuracy ◽  
Star Catalog ◽  
Naval Observatory ◽  
Celestial Reference System ◽  
First Time ◽  
Better Than

The Second Cape Photographic Catalog (CPC2) contains 276,131 stars covering the entire Southern Hemisphere in a 4-fold overlap pattern. Its mean epoch is 1968, which makes it a key catalog for proper motions. A new reduction of the 5687 plates using on average 40 Hipparcos stars per plate has resulted in a vastly improved catalog with a positional accuracy of about 40 mas (median value) per coordinate, which comes very close to the measuring precision. In particular, for the first time systematic errors depending on magnitude and color can be solved unambiguously and have been removed from the catalog. In combination with the Tycho Catalogue (mean epoch 1991.25) and the upcoming U.S. Naval Observatory CCD Astrograph Catalog (UCAC) project proper motions better than 2 mas/yr can be obtained. This will lead to a vastly improved reference star catalog in the Southern Hemisphere for the final Astrographic Catalogue (AC) reductions, which will then provide propermotions for millions of stars when combined with new epoch data. These data then will allow an uncompromised reduction of the southern Schmidt surveys on the International Celestial Reference System (ICRS).

scholarly journals A NEW MYODITES (RHIPIPHORIDÆ)

1902 ◽  
Vol 34 (11) ◽  
pp. 293-294
Author(s):  
W. Dwight. Pierce
Keyword(s):  
Field Observations ◽  
The University ◽  
Yellowish White

The specimens on which this description is based are in the collections of the University of Nebraska and of the author. I owe especial acknowledgments to Mr. J. C. Crawfrod, Jr., for specimens and field observations, andto professor Bruner for directing my work.A sixteen-power glass was used in determining characters.Myodites solidaginis, n. sp. – Female: Length, 7.9 mm. Head depressed, finely and evenly punctate, clad with dense yellowish-white, perpendicular pubescence; antennæ pectinate, ten-jointed, pubescent, very finely punctate, third joint with base of tooth yellowish; vertex between antennæ elevated; mandibles with the exterior side finely punctate, densely pubescent, grooved, in front and on interior sides shining glabrous. Thorax densely punctate, with median groove, but becoming mesially carinate behind the centre, clad with dense, upright, yellowish-white pubescence.

DIGITAL ZENITH CAMERA FOR VERTICAL DEFLECTION DETERMINATION

2012 ◽  
Vol 38 (4) ◽  
pp. 123-129 ◽  
Author(s):  
Māris Abele ◽  
Jānis Balodis ◽  
Inese Janpaule ◽  
Ieva Lasmane ◽  
Augusts Rubans ◽  
...  
Keyword(s):  
Data Processing ◽  
Digital Imaging ◽  
High Accuracy ◽  
Reference Star ◽  
Research Groups ◽  
Vertical Deflection ◽  
Digital Imaging Technology ◽  
Prototype Instrument ◽  
Automated Determination

Recent accomplishments in advancement of accurate astrometric reference star catalogues, development of digital imaging technology, high accuracy tiltmeter technology, and geocentric coordinate availability provided by GNSS, have made possible accurate, fast and automated determination of vertical deflections using astrometric methods. Zenith cameras for this kind of measurements have been developed or are being developed by several research groups. The paper describes a research project by Institute of Geodesy and Geoinformation, intended to design a portable digital zenith camera for vertical deflection determination with 0.1” expected accuracy. Camera components are described, proposed data processing algorithm and preliminary results, obtained with prototype instrument, are presented.

scholarly journals Evaluation of the geriatric curriculum implemented at Shiraz University of Medical Sciences, Iran, since 2017: A qualitative study

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 417 ◽  
Author(s):  
Faezeh Jaafari ◽  
Somayeh Delavari ◽  
Leila Bazrafkan
Keyword(s):  
Medical Students ◽  
Clinical Education ◽  
Group Discussion ◽  
Geriatric Medicine ◽  
General Medicine ◽  
Ambulatory Setting ◽  
Field Observations ◽  
Medical Sciences ◽  
Structured Interviews ◽  
The University

Background: Recently, there has been an increase in life expectancy due to improvements in nutrition, health, and sanitation. The aim of this study was to evaluate the geriatric curriculum in the field of general medicine at Shiraz University of Medical Sciences (SUMS), Iran to improve the quality of services provided to this population in the community. Methods: This was a qualitative study­­. Six educational hospitals and ambulatory centers of Shiraz University of Medical Sciences participated in this study. Within these centers, 15 medical education faculty members and educational experts, 6 medical students, 6 elderly patients and 6 nurses working in the university related to the geriatric field were selected using purposive sampling. Data were gathered through semi-structured interviews, focus group discussion and field observations in the teaching hospital and ambulatory setting of SUMS from June 2017 to May 2018.  Based on the qualitative research, the data underwent conventional content analysis and the main themes were developed from this. Results: Three main themes were extracted from the data: effective clinical education, geriatrics curriculum challenges and promotion strategies for geriatric medicine. Subcategories that emerged were a competent curriculum teacher, a challenging program, management of resources, promotion of the program, and the revision required in the curriculum, which were related to other concepts and described in the real-world situation of the geriatric curriculum in the university, as observed in field observations. Conclusions: This study identified three concepts as main themes that can be used to explain how to implement a geriatric curriculum in a medical university. The main contributing factor to different views of the participants was identified as the revision required to the curriculum for integrative care in a geriatric patient. This should be taken into consideration while planning any programs and decisions aimed at education of medical students on this topic.

scholarly journals Improvement of the Optical Reference System by Photographic Astrometry: First Results of Simulations with Global Block Adjustment Methods

1991 ◽  
Vol 127 ◽  
pp. 399-403
Author(s):  
N. Zacharias
Keyword(s):  
Reference System ◽  
Systematic Errors ◽  
Reference Star ◽  
Star Catalog ◽  
Optical Reference ◽  
First Results

AbstractBlock adjustment (BA) simulations of an entire hemisphere show major improvements in individual as well as systematic accuracy of star positions obtained by photographic astrometry, independent of systematic errors of the reference star catalog used. Results for the accuracy estimates obtained from a patch-like plate pattern in the sky are not valid for closed plate pattern. The importance of BA methods for the realisation of a reference system is stressed.

ALFA crowded star field observations: experiences, data reduction, and future strategies

2000 ◽  
Author(s):  
David J. Butler ◽  
Richard I. Davies ◽  
Markus Feldt
Keyword(s):  
Data Reduction ◽  
Field Observations ◽  
Star Field

scholarly journals Seismic performance analysis and assessment of a precast bridge computational model

DYNA ◽  
2020 ◽  
Vol 87 (212) ◽  
pp. 80-89
Author(s):  
José Benjumea ◽  
Mehdi Saiidi ◽  
Ahmad Itani
Keyword(s):  
Performance Analysis ◽  
Computational Model ◽  
Seismic Performance ◽  
Earthquake Engineering ◽  
Large Scale ◽  
Three Dimensional ◽  
Shake Table ◽  
Bridge Model ◽  
Precast Elements ◽  
The University

A large-scale, two-span bridge model constructed by assembling precast elements was tested under a series of bi-axial ground motionssimulated on a shake table at the Earthquake Engineering Laboratory at the University of Nevada, Reno. The response of the bridge wasestimated before the tests using a three-dimensional computational model developed in OpenSees software. After the tests, key measuredseismic responses were compared to those predicted by the computational model to assess the modeling assumptions. Relatively largeerrors for the displacements, base shears, and hysteretic response of the bridge were observed. The influence of the earthquake loading,materials, connectivity of the precast elements, and boundary conditions in the computational model on the errors are discussed in thispaper. Future modeling directions are proposed to reduce these errors.

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