Chen P.,National Chung Cheng University |
Wang C.-H.,National Space Organization NSPO |
Ho J.-R.,National Central University
Computers and Mathematics with Applications | Year: 2013
A first-order extended lattice Boltzmann (LB) model with special forcing terms for one-dimensional Maxwell equations exerting on a dispersive medium, described either by the Debye or Drude model, is proposed in this study. The time dependent dispersive effect is obtained by the inverse Fourier transform of the frequency-domain permittivity and is incorporated into the LB evolution equations via equivalent forcing effects. The Chapman-Enskog multi-scale analysis is employed to ensure that proposed scheme is mathematically consistent with the targeted Maxwell's equations at the macroscopic limit. Numerical validations are executed through simulating four representative cases to obtain their LB solutions and compare those with the analytical solutions and existing numerical solutions by finite difference time domain (FDTD). All comparisons show that the differences in numerical values are very small. The present model can thus accurately predict the dispersive effects, and demonstrate first order convergence. In addition to its accuracy, the proposed LB model is also easy to implement. Consequently, this new LB scheme is an effective approach for numerical modeling of EM waves in dispersive media. © 2013 Elsevier Ltd. All rights reserved.
Peng T.-S.,National Taiwan University |
Huang Y.-W.,National Taiwan University |
Wang L.A.,National Taiwan University |
Liu R.-Y.,National Space Organization NSPO |
Chou F.-I.,National Tsing Hua University
IEEE Transactions on Nuclear Science | Year: 2010
Two erbium doped fibers (EDFs) with different radiation sensitivities were used in the photo-annealing tests, and their photo-annealing efficiencies were compared by using 532-nm and 976-nm lasers. For both EDFs, the 532-nm laser with 10 mW showed better efficiency than 976-nm laser with 290 mW. The radiation induced attenuation (RIA) could nearly be diminished in the wavelength range from 900 nm to 1700 nm by the photo-annealing of 532-nm laser. The half-time of recovery was 5.6 seconds by using 532-nm laser, and was about 40 minutes by using 976-nm laser whose annealing rate was similar to that of purely thermal annealing at about 330° C. For γ -irradiation tests of superfluorescent fiber sources (SFSs) exposed to a dose rate of 129.2 krad/hr, the rate of output power loss could be reduced by the 976-nm pump laser, but the output power loss could not be recovered. A most radiation-tolerant case was an SFS with 2.8-meter EDF#1 co-pumped by both the 532 nm and the 976 nm lasers. The output power loss could be recovered with a rate of 0.009 dB/min. © 2010 IEEE.
Peng T.-S.,National Taiwan University |
Wang L.A.,National Taiwan University |
Liu R.-Y.,National Space Organization NSPO
IEEE Photonics Technology Letters | Year: 2011
A novel feedback control method by tuning reflectivity was demonstrated for stabilizing mean-wavelength of a double-pass backward (DPB) superfluorescent fiber source (SFS) under 60 Co irradiation. The mean-wavelength drift was compensated with increasing dose up to 22 krad, suitable for the applications in the low Earth orbit. The rate of output power loss induced by irradiation could be decreased by 33% when the feedback control was working. The linewidth of the DPB SFS was 16 nm, 1.6 times larger than the reported one by adding an output edge filter. With such a larger linewidth the angle random walk (ARW) of an IFOG can be more reduced. © 2011 IEEE.
Hwang F.-T.,National Space Organization NSPO |
Hsueh C.-W.,National Space Organization NSPO |
Lin H.-C.,Syscom Inc.
14th International Conference on Space Operations, 2016 | Year: 2016
FORMOSAT-7 mission, the follow-up mission of FORMOSAT-3,is the second joint space program between Taiwan and USA. The program plans to deploy a constellation of 12 mission satellites where 6 out of them are in low inclination orbit and others are in high inclination orbit. In addition to mission satellites, NSPO will launcha self-developed auxiliary satellite to this mission and serves as the demonstration platform of 300-kgclass small satellite and a variety of component technologies. The primary payload for FORMOSAT-7 is the radio occultation receiver, which measure the signals from navigation satellites, such as GPS, GLONASS, or Galileo, to obtain the data values of atmospheric pressure, temperature, and humility and so on. Currently, the first set of 6 mission satellites is scheduled to be launched through Falcon-9 Heavy rocket in the year of 2017. To ensure the success of entire space mission and meet the requirements from users’side, mission analysis plays a key role in the initial stage of a satellite program. For FORMOSAT-7 mission, the tasks of mission analysis were conducted by systems engineering division of NSPO and USA partners. In this paper, three analysis results, which were done by NSPO, for FORMOSAT-7 mission are presented. The first part is a constellation design and its deployment method, the second part is a mission orbit selection, and the third part is uniformity analysis of data distribution. For constellation design of first set of FORMOSAT-7 satellites, a pattern of Walker constellations is selected based on the consideration of operational constraint. For the selection of an initial mission orbit, the orbit selection is from results of a multi-objective optimization process. Finally, data uniformity is one of important index to measure the performance of entire systems. Both global uniformity and local uniformity index are proposed in this paper to measure spatial and temporal uniformity of data distribution for FORMOSAT-7 constellation. These quantitative results can further verify the rationality of our selected constellation structure. Finally, the deployment strategy of the NSPO-built spare satellite for FORMOSAT-7 mission is also addressed in this study. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
Chern J.-S.,China University of Science and Technology |
Lin S.-F.,National Space Organization NSPO |
Wu A.-M.,National Space Organization NSPO
Acta Astronautica | Year: 2011
This paper presents the enhancement in mission operations, the mission life state-of-health (SOH) trending analysis, and the post mission life plan of the FORMOSAT-2 (or FS2, Formosa satellite #2, was called ROCSAT-2, or RS2, Republic of China satellite #2, previously) during its five years mission life from 20 May 2004 to 20 May 2009. There are two payloads onboard FS2: a remote sensing instrument (RSI) with nadir ground sampling distance (GSD) of 2 m for panchromatic (PAN) and GSD of 8 m for multi-spectral (MS, 4 bands) as the primary payload, and an imager for sprite and upper atmospheric lightning (ISUAL) as the secondary payload. It was launched on 20 May 2004. The design life is 7 years while the mission life is 5 years. In other words, the end of mission life date of FS2 is 20 May 2009. Generally speaking, FS2 is still at very good condition in its SOH. Post mission life plan for FS2 consists of: the practice of orbit transfer for global coverage and better resolution, the development of gyroless attitude control, and the method for life extension. It is expected that the working life of FS2 can be extended 35 years. © 2010 Elsevier Ltd.
Chan S.-C.,National Tsing Hua University |
Chen C.-R.,National Space Organization NSPO |
Liu C.-H.,National Tsing Hua University
Sensors and Actuators, A: Physical | Year: 2010
With the increasing demand for thermal management in electronic cooling applications, the development of heat dissipation devices has become extremely important. This paper presents the development of a novel bubble-activated micropump with high-frequency flow reversal using embedded electrodes in a closed fluidic microchannel. This bubble-activated micropump consists of a microfluidic chamber structure and microelectrodes on a glass substrate that is assembled using a polydimethylsiloxane (PDMS) elastic sheet. First, the bubble-activated micropump was fabricated on a silicon substrate by spin-coating, curing, and molding using negative photoresist SU-8 2035 as the mold material. Second, a phosphate buffer solution (PBS) was introduced into the micropump chamber to increase the heat dissipation rate via a bubble-based actuator oscillating at a frequency of 300 Hz. The measured maximum flow rate was 37.8 μL/min at an applied voltage of 5 V. This study furthers the development of cooling systems using a bubble-activated design by achieving stable performance. © 2010 Elsevier B.V. All rights reserved.
Hwang F.-T.,National Space Organization NSPO
34th Asian Conference on Remote Sensing 2013, ACRS 2013 | Year: 2013
The aim of this paper is to analyze current development status of high resolution (GSD 4 meter) optical earth observation satellite systems and portray future trends of their developments. The technical data of high resolution optical earth observation satellite are collected from public domains, such as web sites, open literatures etc., and development status of remote sensing satellites are described through three categories: (1) image sensors, (2) spacecraft capability, and (3) orbit characteristics. Finally, based on our analysis, several development trends are also observed. NSPO of Taiwan not only owes and operates FORMOSAT-2 remote sensing satellite, but also indigenously develops its FORMOSAT-5, scheduled to be launched in 2015. These activities demonstrate NSPO's determination to compete in the world arena of earth observation satellites. With those trends in mind, NSPO's plan for next generation remote sensing satellites becomes realistic and tangible.
Chang C.-L.,National Space Organization NSPO |
Fu L.-Y.,National Tsing Hua University
34th Asian Conference on Remote Sensing 2013, ACRS 2013 | Year: 2013
This study assesses the effects of science and culture learning through an innovative tribal tourism developed in Atayal Satellite Program. The purposes of this tourism model are using indigenous-culture tourism to develop the tribal economy, promoting a leisure activity for learning satellite basics and applications and developing a sustainable environment for indigenous tourism. The model is feasible according to quantitative analysis of Test of Science Related Attitudes (TOSRA), the other questionnaires and interviews with tribal villagers, who took part in the program, and participants, who participated in the camps. The study reveals positive responses to the activities of the Atayal Satellite Program and significantly positive effects of science and culture learning in the Atayal Satellite Program.
Wu A.-M.,National Space Organization NSPO |
Ni W.-T.,National Tsing Hua University
International Journal of Modern Physics D | Year: 2013
Constellation or formation flying is a common concept in space Gravitational Wave (GW) mission proposals for the required interferometry implementation. The spacecraft of most of these mission proposals go to deep space and many have Earthlike orbits around the Sun. Astrodynamical Space Test of Relativity using Optical Devices optimized for Gravitation Wave detection (ASTROD-GW), Big Bang Observer (BBO) and DECIGO have spacecraft distributed in Earthlike orbits in formation. The deployment of orbit formation is an important issue for these missions. ASTROD-GW is to focus on the goal of detection of GWs. The mission orbits of the three spacecraft forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The three spacecraft range interferometrically with one another with arm length about 260 million kilometers with the scientific goals including detection of GWs from Massive Black Holes (MBH) and Extreme-Mass-Ratio Black Hole Inspirals (EMRI), and using these observations to find the evolution of the equation of state of dark energy and to explore the co-evolution of MBH with galaxies. In this paper, we review the formation flying for fundamental physics missions, design the preliminary transfer orbits of the ASTROD-GW spacecraft from the separations of the launch vehicles to the mission orbits, and simulate the arm lengths of the triangular formation. From our study, the optimal delta-Vs and propellant ratios of the transfer orbits could be within about 2.5 km/s and 0.55, respectively. From the simulation of the formation for 10 years, the arm lengths of the formation vary in the range 1.73210 ± 0.00015 AU with the arm length differences varying in the range ±0.00025 AU for formation with 1° inclination to the ecliptic plane. This meets the measurement requirements. Further studies on the optimizations of deployment and orbit configurations for a period of 20 years and with inclinations between 1° to 3° are currently ongoing. © 2013 World Scientific Publishing Company.
Hung H.-C.,National Space Organization NSPO
69th International Conference on Mass Properties 2010 | Year: 2010
The "FORMOSAT-3 Program " is an international collaboration project between Taiwan and the US with joint efforts of Taiwan's National SPace Organization (NSPO) and University Corporation for Atmospheric Research (UCAR) of the US. The primary FORMOSAT-3 mission is to launch a constellation of six micro-satellites into Low-Earth Orbit (LEO) in altitude range 700 ∼ 800 Km to collect atmospheric data for weather prediction, atmospheric studies, space weather monitoring and geodetic research. The satellites integration and test were completed at NSPO I&T Facility located in Hsinchu, Taiwan. The objective of this paper is to present the method developed at NSPO to improve Moment Of Inertia (MOI) measurement accuracy for FORMOSAT-3 satellites. The Mass Properties Measurement Facility (MPMF) at NSPO is designed for three axes mass properties measurement of satellite up to 1500 Kg. The MPMF includes a 980 Kg weight L-Fixture for horizontal axes measurement. This "huge " L-Fixture greatly reduces the sensitivity of the MOI measurement for FORMOSAT-3 micro-satellites each weighs only about 62 Kg. Redesign of a smaller L-Fixture is inevitable. However, the L-Fixture is designed so that the test objective is well aligned with the MPMF, to manufacture a new one would be too costly and too time consuming. Decision was made to design a smaller fixture without looking for the alignment problem. The alignment problem is solved later when performing the measurement. The Alignment Measurement Equipment is used to accurately identify the misalignment when the satellite is installed in position for measurement. The misalignment data is then used to correct the MOI data. Although the satellite installed with smaller fixture is not well aligned to the MPMF, the misalignment is well measured. The MOI data can be accurately corrected with the alignment data. The final results show that accuracy has been dramatically improved with this method.