scholarly journals Experimental system for studying the effect of the arrangement of nonhermetic module fillers on the outgassing flow density

2020 ◽  
Vol 2020 (4) ◽  
pp. 82-96
Author(s):  
A.M. Aksiutenko ◽  
◽  
Yu.P. Yefymov ◽  
R.A. Kantserova ◽  
M.V. Petrushenko ◽  
...  
Keyword(s):  
Experimental System ◽  
Measuring System ◽  
Flow Density ◽  
National Academy Of Sciences ◽  
Small Spacecraft ◽  
Space Agency ◽  
Frequent Use ◽  
Experiment Control ◽  
Space Projects ◽  
And Performance

In recent years, components and materials of industrial and commercial quality have been in frequent use in the assembly of small spacecraft to reduce the cost of space projects. This may affect spacecraft and onboard equipment reliability and performance quality. In particular, a high risk may arise from unpredictable performance characteristics of components and materials of this type caused by outgassing flows of unregulated density. The situation is aggravated by difficulties in numerical simulation of the complex internal geometry of actual nonhermetic small spacecraft. The most efficient way to resolve this problem is to conduct laboratory tests. This paper presents an experimental system for studying the dependence of degassing processes on the geometry of arrangement of electronics boards and various structural materials in a nonhermetic module. The theoretic basis for experiments is a differential realization of the accumulation method, which allows one to differentiate the density of degassing flows from particularly arranged specimens and elements of the module’s inner surface. To reproduce the design features of nonhermetic nano- and picosatellites, models of nonhermetic modules were refined, and a special laboratory module was made on their basis. For this purpose, a unit of synchronous module evacuation control was updated, equipment was developed for positioning plate-type fillers of nonhermetic modules, the recording of gas-dynamic parameters of a nonhermetic module’s own internal atmosphere was provided, and an automated experiment control system was prepared. The laboratory module was integrated into the automated measuring system of the VAU-2M vacuum aerodynamic installation of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine. The experimental system developed was tested to show a satisfactory operability of both its components and the system as a whole. The system developed allows one to study outgassing from the surface of various components and materials, to measure the density of outgassing flows for various equipment arrangements, and to study the dynamics of outflow of the products of the own internal atmosphere through calibrated orifices, which simulate the outflow of the own internal atmosphere of a nonhermetic module through its unregulated clearances.

A virtual test environment for validating spacecraft optical navigation

2013 ◽  
Vol 117 (1197) ◽  
pp. 1075-1101 ◽  
Author(s):  
S. M. Parkes ◽  
I. Martin ◽  
M. N. Dunstan ◽  
N. Rowell ◽  
O. Dubois-Matra ◽  
...  
Keyword(s):  
Small Body ◽  
European Space Agency ◽  
Ground Truth ◽  
Camera Motion ◽  
Test Environment ◽  
Space Applications ◽  
Vision Guidance ◽  
Space Agency ◽  
Wide Range ◽  
And Performance

Abstract The use of machine vision to guide robotic spacecraft is being considered for a wide range of missions, such as planetary approach and landing, asteroid and small body sampling operations and in-orbit rendezvous and docking. Numerical simulation plays an essential role in the development and testing of such systems, which in the context of vision-guidance means that realistic sequences of navigation images are required, together with knowledge of the ground-truth camera motion. Computer generated imagery (CGI) offers a variety of benefits over real images, such as availability, cost, flexibility and knowledge of the ground truth camera motion to high precision. However, standard CGI methods developed for terrestrial applications lack the realism, fidelity and performance required for engineering simulations. In this paper, we present the results of our ongoing work to develop a suitable CGI-based test environment for spacecraft vision guidance systems. We focus on the various issues involved with image simulation, including the selection of standard CGI techniques and the adaptations required for use in space applications. We also describe our approach to integration with high-fidelity end-to-end mission simulators, and summarise a variety of European Space Agency research and development projects that used our test environment.

scholarly journals Cloud Effective Emissivity Retrievals Using Combined Ground-Based Infrared Cloud Measuring Instrument and Ceilometer Observations

2018 ◽  
Vol 10 (12) ◽  
pp. 2033
Author(s):  
Lei Liu ◽  
Ting Zhang ◽  
Yi Wu ◽  
Zhencong Niu ◽  
Qi Wang
Keyword(s):  
Measuring System ◽  
Measuring Instrument ◽  
Effective Emissivity ◽  
Retrieval Method ◽  
Clear Sky ◽  
Inversion Procedure ◽  
The Mean ◽  
And Performance ◽  
Emissivity Measurements ◽  
Good Agreement

In this paper, a new inversion procedure for cloud effective emissivity retrievals using a combined ground-based infrared cloud measuring instrument with ceilometer was developed. A quantitative sensitivity and performance analysis of the proposed method was also provided. It was found that the uncertainty of the derived effective emissivity was mainly associated with errors on the measurement radiance, the simulated radiance of clear sky and blackbody cloudy sky. Furthermore, the retrieval at low effective emissivity was most sensitive to the simulated clear sky radiances, whereas the blackbody cloudy sky radiance was the prevailing source of uncertainty at high emissivity. This newly proposed procedure was applied to the measurement taken in the CMA Beijing Observatory Station from November 2011 to June 2012 by the whole-sky infrared cloud-measuring system (WSIRCMS) and CYY-2B ceilometer. The cloud effective emissivity measurements were in good agreement with that of the MODIS/AQUA MYD06 Collection 6 (C6) cloud products. The mean difference between them was 0.03, with a linear correlation coefficient of 0.71. The results demonstrate that the retrieval method is robust and reliable.

Real-Time Measuring System for Engine Exhaust Solid Particle Number Emission - Design and Performance

2006 ◽  
Author(s):  
Qiang Wei ◽  
Karl Oestergaard ◽  
Scott Porter ◽  
Asano Ichiro ◽  
Masayuki Adachi ◽  
...  
Keyword(s):  
Real Time ◽  
Solid Particle ◽  
Particle Number ◽  
Measuring System ◽  
Engine Exhaust ◽  
And Performance

Simulation analysis and performance of a feasible GNSS system with multi-beam antennas deployment operating in Galileo frequency bands

2012 ◽  
Vol 4 (5) ◽  
pp. 537-543
Author(s):  
Constantinos T. Angelis
Keyword(s):  
Simulation Analysis ◽  
European Space Agency ◽  
Satellite System ◽  
Access Time ◽  
Maximum Efficiency ◽  
Satellite Systems ◽  
Space Agency ◽  
Simulation Results ◽  
And Performance ◽  
Global Navigation Satellite

New Global Navigation Satellite System (GNSS) systems under development, such as Galileo, are very promising for future global positioning-based applications. A vast research is undergoing a final stage of implementation in order to fulfill the primary purpose of European Space Agency for developing and then sustaining of 30 (27 + 3 spares) Galileo satellites in orbit. This article presents simulation results for a realistic deployment of multibeam antennas, with a new modified theoretical pattern, in GNSS Satellite Systems. The proposed multibeam antennas use 61-spot beams for maximum efficiency in terms of satellite coverage and accessing high quality of service. In order to prove the reliability and feasibility of this work, various simulations were conducted using the upcoming Galileo system as a platform taking into consideration real-world conditions. Gain analysis versus elevation, Bit Error Rate (BER) and access time simulation results show that the viability of the proposed multibeam antenna deployment is established.

scholarly journals The Hipparcos Catalogue: 10th anniversary and its legacy

2007 ◽  
Vol 3 (S248) ◽  
pp. 1-7
Author(s):  
C. Turon ◽  
F. Arenou
Keyword(s):  
Historical Perspective ◽  
European Space Agency ◽  
Space Missions ◽  
Basic Principles ◽  
10Th Anniversary ◽  
Science Programme ◽  
Space Agency ◽  
Hipparcos Catalogue ◽  
Giant Step ◽  
And Performance

AbstractThe European Space Agency decision to include the Hipparcos satellite into its Science Programme is placed in the context of the years 1965-1980 and in the historical perspective of the progress of astrometry. The motivation and ideas which lead to the Hipparcos design are reviewed as well as its characteristics and performance. The amount and variety of applications represent an impressive evolution from the original science case and opened the way to much more ambitious further space missions, especially Gaia, based on the same basic principles. A giant step in technology led to a giant step in science. Next steps are presented at this Symposium.

scholarly journals A Comparative Analysis of Writing Strategies and Performance in a Saudi University

2018 ◽  
pp. 425-443
Author(s):  
Miriam Alkubaidi
Keyword(s):  
English Language ◽  
First Language ◽  
Writing Strategies ◽  
Writing Proficiency ◽  
Writing Performance ◽  
Frequent Use ◽  
Significant Difference ◽  
Efl Students ◽  
And Performance ◽  
The Relationship

There has been a widespread utilization of the English language in Saudi Arabia, due to which it is necessary for Saudi citizens to gain an adequate grip on this language. This study aimed to conduct a comparative evaluation between the writing strategies and writing performance shown by Saudi EFL students. Seventy-four female undergraduates between 21 and 25 years and having Arabic as their first language were recruited for this study. The writing samples of the participants were typed into the computer so that no inconsistency takes place based on the students’ writing skills by the researcher. Descriptive statistics were then used to ascertain the level of strategy use of the participants. These students were divided into two groups, based on high and low writing proficiencies. It was found that there was no significant difference in writing performance of these students. The students, who demonstrated a higher level of writing proficiency while writing stood at a percentage of 47.3%; whereas, students demonstrating a low level of writing proficiency stood at a percentage of 44.6%. Furthermore, most of the students used drafting strategies as compared to ‘before-writing’ strategies. More frequent use of ‘before-writing’ strategies is encouraged. Further research is needed regarding the relationship between writing strategy application and the writing performance of these learners

scholarly journals AP-XPS beamline, a platform for operando science at Pohang Accelerator Laboratory

2020 ◽  
Vol 27 (2) ◽  
pp. 507-514
Author(s):  
Geonhwa Kim ◽  
Youngseok Yu ◽  
Hojoon Lim ◽  
Beomgyun Jeong ◽  
Jouhahn Lee ◽  
...  
Keyword(s):  
High Resolution ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Experimental System ◽  
Photon Flux ◽  
Acceptance Angle ◽  
X Ray ◽  
Pohang Accelerator Laboratory ◽  
And Performance ◽  
X Ray Absorption

Beamline 8A (BL 8A) is an undulator-based soft X-ray beamline at Pohang Accelerator Laboratory. This beamline is aimed at high-resolution ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), soft X-ray absorption spectroscopy (soft-XAS) and scanning photoemission microscopy (SPEM) experiments. BL 8A has two branches, 8A1 SPEM and 8A2 AP-XPS, that share a plane undulator, the first mirror (M1) and the monochromator. The photon beam is switched between the two branches by changing the refocusing mirrors after the monochromator. The acceptance angle of M1 is kept glancing at 1.2°, and Pt is coated onto the mirrors to achieve high reflectance, which ensures a wide photon energy range (100–2000 eV) with high resolution at a photon flux of ∼1013 photons s−1. In this article, the main properties and performance of the beamline are reported, together with selected experiments performed on the new beamline and experimental system.

scholarly journals LESSONS FROM THE INAUGURAL SATELLITE DESIGN CHALLENGE

2013 ◽  
Author(s):  
Dario Schor ◽  
Kane Anderson ◽  
Ahmad Byagowi ◽  
Brady Russell ◽  
Scott McKay ◽  
...  
Keyword(s):  
Experiential Learning ◽  
Technical Skills ◽  
Learning Opportunities ◽  
Satellite Design ◽  
Requirements Specifications ◽  
Space Agency ◽  
University Of Manitoba ◽  
Design Challenge ◽  
And Performance ◽  
Definition Of

The inaugural Canadian Satellite Design Challenge provided many experiential learning opportunities for students through the design, implementation, and testing of the T-Sat1 nanosatellite.The University of Manitoba team elected to build all components from the ground up in order to develop many technical and non-technical skills that complement the classroom experience.The first phases of the project focused on the definition of requirements, specifications, and interfaces. Then, the team began prototyping, implementing, and integrating subsystems. Finally, the spacecraft was tested at the Canadian Space Agency laboratories in Ottawa and obtained second place overall in the competition.This paper describes some of the major lessons from the implementation, integration, and testing phases of the project. In addition, some insight is provided as to the ongoing changes for the second iteration of the competition that aim at improving the experience and performance of the satellite.

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