THE UPDATED ORBITAL EPHEMERIS OF DIPPING LOW MASS X-ray BINARY 4U 1624-49

LIAO, NAI-HUI,CHOU, YI,HSIEH, HUNG-EN,CHUANG, PO-SHENG The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

We present our analysis results for an updated orbital ephemeris for the dipping low mass X-ray binary 4U 1624-49, using the light curve collected by the All Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the Monitor of All-Sky X-ray Image (MAXI). To make clear dip profiles, the light curve from the ASM and the MAXI were divided into ten 500d segments and four 400d segments for ASM and MAXI light curves, respectively, and folded with the linear ephemeris proposed by Smale et al. (2001). The phases of dip centers were determined by the method adopted from Hu et al. (2008). The phase drift was then fitted with a linear function. We obtained an updated orbital period of 0.869896(1) d and a phase zero epoch of JD 2450088.6618(57). No clear orbital period derivative is detected with a 2-sigma upper limit of $1.4{\times}10^{-6}(yr)^{-1}$ from a quadratic curve fitting of the dip phase evolution.

An Adaptive Learning System based on Cloud Computing : Implementation and Evaluation of BDS

Yi Liao,Lei Huang,Hang Zhou,Bo Li 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.8

In this paper, we report the design and implementation of an adaptive individualized e-learning environment based on cloud computing named BDS (Beijing Digital School). With its five-layer architecture and its use of cloud computing technology, BDS possesses the characteristics of both a massive access system and an adaptive e-learning environment. This paper focuses on investigating three distributed solutions proposed for load balancing: an active clustering algorithm, a random algorithm and a honey bee foraging algorithm. An experiment comparing 2 groups of students was conducted to evaluate the impact of the proposed environment on learning performance, and the results were analyzed to determine the most effective strategy.

Newly-Constructed Single-Phase Multistring Multilevel Inverter for Fuel-Cell Microgrid

Yi-Hung Liao,Ching-Ming Lai 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The objective of this paper is to construct a novel transformerless five-level multistring inverter topology for fuel-cell microgrid system. In this study, a high step-up converter is introduced as a front-end stage to improve the conversion efficiency of conventional boost converters and to stabilize the output DC voltage of various DERs such as PV and fuel cell modules for use with the simplified multilevel inverter. The simplified multilevel inverter requires only six active switches instead of the eight required in the conventional H-bridge cascaded multilevel inverter. In addition, two active switches are operated under line frequency. The presented multistring inverter offers strong advantages such as improved output waveforms, smaller filter size, and lower EMI and THD. Experimental results show the effectiveness of the proposed solution.

THE ORBITAL EPHEMERIS OF THE PARTIAL ECLIPSING X-ray BINARY X1822-371

HSIEH, HUNG-EN,CHOU, YI,HU, CHIN-PING,YANG, TING-CHANG,SU, YI-HAO,LIN, CHING-PING,CHUANG, PO-SHENG,LIAO, NAI-HUI The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

X1822-371 is a low mass X-ray binary with an accretion disk corona exhibiting partial eclipses and pulsations in the X-ray band. We update its orbital ephemeris by combining new RXTE observations and historical records, with a total time span of 34 years. There were 11 RXTE observations in 2011 but the eclipsing profile can be seen in only 4 of them. The eclipsing center times were obtained by fitting the profile with the same model as previous studies. Combined with the eclipsing center times reported by Iaria et al. (2011), the O-C analysis was processed. A quadratic model was applied to fit the O-C results and produced a mean orbital period derivative of $\dot{P}_{orb}=1.339(25){\times}10^{-10}s/s$, which is slightly smaller than previous records. In addition to the orbital modulation from the orbital profile, we also present our preliminary results for measuring the orbital parameters using the orbital Doppler effect from the pulsation of the neutron star in X1822-371. The updated orbital parameters from eclipsing profiles will be further compared with the ones from pulsar timing.

CHARACTERIZING THE TIME-FREQUENCY PROPERTIES OF THE 4 Hz QUASI-PERIODIC OSCILLATION AROUND THE BLACK HOLE X-ray BINARY XTE J1550-564

SU, YI-HAO,CHOU, YI,HU, CHIN-PING,YANG, TING-CHANG,HSIEH, HUNG-EN,CHUANG, PO-SHENG,LIN, CHING-PING,LIAO, NAI-HUI The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

We present the results from analysis of the Hilbert-Huang transform (HHT) for the 4 Hz quasi-periodic oscillations (QPO) around the black hole X-ray binary XTE J1550-564. The resultant Hilbert spectra demonstrate that the QPO is composed of a series of intermittent signals appearing occasionally. From the analysis of the HHT, we further found the distribution of the lifetimes for the intermittent oscillations and the distribution for the time intervals with no significant signal (the break time). The mean lifetime is 1.45 s and 90% of the oscillation segments have lifetimes less than 3.1 s whereas the mean break time is 0.42 s and 90% of break times are less than 0.73 s. We conclude that the intermittent feature of the QPO could be explained by the Lense-Thirring precession model and rules out interpretations of continual frequency modulation.

Electrical current induced mechanism in microstructure and nano-indention of Al–Zn–Mg–Cu (AZMC) Al alloy thin film

Fei-Yi Hung,Jiunn-Der Liao,Truan-Sheng Lui,Li-Hui Chen 한국물리학회 2011 Current Applied Physics Vol.11 No.6

In this study, the microstructural variation and nano-indention of Al-5.7Zn-2.4Mg-1.5Cu (AZMC) thin film was investigated using DC electrical current at a density of 1000 A/cm^2. The results show that microstructural changes due to the electrical current involved both the solid solubility effect and enhanced diffusion. The electrical current drove the Al atoms and Cu atoms of the matrix from the cathode to the anode. After electrical current testing, precipitation phases (Al_2Cu; CuMgAl_2) had decomposed into the cathode matrix and MgZn phases had grown in the anode zones. Meanwhile, the current also caused the hardness of the thin film to decrease and affected both the texture and dynamic strain mechanism of nano-indention.

A Family of Single-Stage Single-Switch PV MICs with Steep Conversion Gain

Ching-Ming Lai,Yi-Hung Liao 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In this paper, a family of single-stage single-switch photovoltaic (PV) module integrated converters (MICs) with steep voltage conversion gain capability and galvanic isolation is presented. As an illustration, the new MIC topology based on the isolated-type single-ended primary-inductor converter (Sepic) with coupled inductor is analyzed and developed. Moreover, a fast maximum power point tracking (MPPT) strategy with linear current control is adapted in the proposed SEPIC-type PV MIC. Finally, a speciation of single-phase 150W prototype is constructed, and experimental results indeed verify the effectiveness of the proposed converter.

The Effects of Low Volume Versus High Volume Sled-Push Training on Muscular Adaptation

( Jeffrey R. Bernard ),( Yi-hung Liao ),( Christian O. Madrigal ),( Joshua D. Levesque ),( Matthew B. Fraze ),( Isaac Del Toro ),( Sukho Lee ) 한국운동생리학회(구 한국운동과학회) 2021 운동과학 Vol.30 No.2

PURPOSE: This study aimed to compare the effects of low-volume and high-volume sled-push resistance training on muscle strength, power, and body composition. METHODS: Twenty-four college students were recruited and matched based on baseline one-repetition maximum (1-RM) into one of the three groups: 1) low volume (LV) resistance training, 2) high volume (HV) resistance training, or 3) control (CON) (n=8 per group). The LV training consisted of five single repetitions of pushing a weighted sled for 9.1 m. The HV training consisted of three sets of five repetitions of pushing a weighted sled for 9.1 m. Training consisted of three weekly workouts performed on nonconsecutive days for 6 weeks. This study utilized a pre-test and post-test design consisting of 1-RM, Wingate power test, standing long jump, vertical jump, and body composition. RESULTS: After 6 weeks of training, there was a similar but significant increase in 1-RM in both training groups (pre-test: LV=226.8±14.8 kg vs. HV=217.7±19.5 kg; post-test: LV=298.5±15 kg vs. HV=286.9±16 kg, p< .001). However, no improvements were observed in the Wingate power test, standing long jump, vertical jump, or body composition in both training and CON groups (p >.05). CONCLUSIONS: The results suggested that low-volume resistance training was as effective as a high-volume protocol for improving muscle strength. However, the present study was unable to determine the effects on muscle power and body composition.

THE UPDATED ORBITAL PERIOD OF LOW MASS X-ray BINARY 4U 1323-62

CHUANG, PO-SHENG,CHOU, YI,HU, CHIN-PING,YANG, TING-CHANG,SU, YI-HAO,LIAO, NAI-HUI,HSIEH, HUNG-EN,LIN, CHING-PING The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

4U 1323-62, a low mass X-ray binary with an orbital period of 2.94 hr, exhibits periodic X-ray dips, which are due to absorption by the bulge of the outer accretion disk. The purpose of this study is to search for orbital period changes using archived X-ray data over a time span of 20 years. We present our preliminary results from analyzing light curves observed by RXTE, BeppoSAX, XMM-Newton and Suzaku. We used the method proposed by Hu et al. (2008) to estimate dip center time and adopted the Observed - Calculated method to measure changes in period. We obtained an orbital period of 2.941917(36) hr and a period derivative of $\dot{P}_{orb}/P_{orb}=(-9.9{\pm}3.5){\times}10^{-7}yr^{-1}$. The F-test result shows that the quadratic ephemeris is describes the evolution of the dip phases better than the linear ephemeris at a greater than 95% confidence level. More X-ray data collected from the early 80s will be included to further refine the orbital ephemeris.

APPLICATIONS OF THE HILBERT-HUANG TRANSFORM ON THE NON-STATIONARY ASTRONOMICAL TIME SERIES

HU, CHIN-PING,CHOU, YI,YANG, TING-CHANG,SU, YI-HAO,HSIEH, HUNG-EN,LIN, CHING-PING,CHUANG, PO-SHENG,LIAO, NAI-HUI The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

The development of time-frequency analysis techniques allow astronomers to successfully deal with the non-stationary time series that originate from unstable physical mechanisms. We applied a recently developed time-frequency analysis method, the Hilbert-Huang transform (HHT), to two non-stationary phenomena: the superorbital modulation in the high-mass X-ray binary SMC X-1 and the quasi-periodic oscillation (QPO) of the AGN RE J1034+396. From the analysis of SMC X-1, we obtained a Hilbert spectrum that shows more detailed information in both the time and frequency domains. Then, a phase-resolved analysis of both the spectra and the orbital profiles was presented. From the spectral analysis, we noticed that the iron line production is dominated by different regions of this binary system in different superorbital phases. Furthermore, a pre-eclipse dip lying at orbital phase ~0:6-0:85 was discovered during the superorbital transition state. We further applied the HHT to analyze the QPO of RE J1034+396. From the Hilbert spectrum and the O-C analysis results, we suggest that it is better to divide the evolution of the QPO into three epochs according to their different periodicities. The correlations between the QPO periods and corresponding fluxes were also different in these three epochs. The change in periodicity and the relationships could be interpreted as the change in oscillation mode based on the diskoseismology model.