A database with enterprise application for mining astronomical data obtained by MOA : a thesis submitted in partial fulfilment of the requirements for the degree of the Master of Information Science in Computer Science, Massey University at Albany, Auckland, New Zealand

The MOA (Microlensing Observations in Astrophysics) Project is one of a new generation of modern astronomy endeavours that generates huge volumes of data. These have enormous scientific data mining potential. However, it is common for astronomers to deal with millions and even billions of records. The challenge of how to manage these large data sets is an important case for researchers. A good database management system is vital for the research. With the modern observation equipments used, MOA suffers from the growing volume of the data and a database management solution is needed. This study analyzed the modern technology for database and enterprise application. After analysing the data mining requirements of MOA, a prototype data management system based on MVC pattern was developed. Furthermore, the application supports sharing MOA findings and scientific data on the Internet. It was tested on a 7GB subset of achieved MOA data set. After testing, it was found that the application could query data in an efficient time and support data mining

Effective Cell-Centred Time-Domain Maxwell's Equations Numerical Solvers

This research work analyses techniques for implementing a cell-centred finite-volume time-domain (ccFV-TD) computational methodology for the purpose of studying microwave heating. Various state-of-the-art spatial and temporal discretisation methods employed to solve Maxwell's equations on multidimensional structured grid networks are investigated, and the dispersive and dissipative errors inherent in those techniques examined. Both staggered and unstaggered grid approaches are considered. Upwind schemes using a Riemann solver and intensity vector splitting are studied and evaluated. Staggered and unstaggered Leapfrog and Runge-Kutta time integration methods are analysed in terms of phase and amplitude error to identify which method is the most accurate and efficient for simulating microwave heating processes. The implementation and migration of typical electromagnetic boundary conditions. from staggered in space to cell-centred approaches also is deliberated. In particular, an existing perfectly matched layer absorbing boundary methodology is adapted to formulate a new cell-centred boundary implementation for the ccFV-TD solvers. Finally for microwave heating purposes, a comparison of analytical and numerical results for standard case studies in rectangular waveguides allows the accuracy of the developed methods to be assessed

Molecular environments of 51 Planck cold clumps in Orion complex

A mapping survey towards 51 Planck cold clumps projected on Orion complex was performed with J=1-0 lines of $^{12}$CO and $^{13}$CO at the 13.7 m telescope of Purple Mountain Observatory. The mean column densities of the Planck gas clumps range from 0.5 to 9.5$\times10^{21}$ cm$^{-2}$, with an average value of (2.9$\pm$1.9)$\times10^{21}$ cm$^{-2}$. While the mean excitation temperatures of these clumps range from 7.4 to 21.1 K, with an average value of 12.1$\pm$3.0 K. The averaged three-dimensional velocity dispersion $\sigma_{3D}$ in these molecular clumps is 0.66$\pm$0.24 km s$^{-1}$. Most of the clumps have $\sigma_{NT}$ larger than or comparable with $\sigma_{Therm}$. The H$_{2}$ column density of the molecular clumps calculated from molecular lines correlates with the aperture flux at 857 GHz of the dust emission. Through analyzing the distributions of the physical parameters, we suggest turbulent flows can shape the clump structure and dominate their density distribution in large scale, but not affect in small scale due to the local fluctuations. Eighty two dense cores are identified in the molecular clumps. The dense cores have an averaged radius and LTE mass of 0.34$\pm$0.14 pc and 38$_{-30}^{+5}$ M_{\sun}, respectively. And structures of low column density cores are more affected by turbulence, while those of high column density cores are more concerned by other factors, especially by gravity. The correlation of the velocity dispersion versus core size is very weak for the dense cores. The dense cores are found most likely gravitationally bounded rather than pressure confined. The relationship between $M_{vir}$ and $M_{LTE}$ can be well fitted with a power law. The core mass function here is much more flatten than the stellar initial mass function. The lognormal behavior of the core mass distribution is most likely determined by the internal turbulence.Comment: Accepted to The Astrophysical Journal Supplement Series (ApJS

Uniform Infall toward the Cometary H II Region in the G34.26+0.15 Complex?

Gas accretion is a key process in star formation. However, the gas infall detections in high-mass star forming regions with high-spatial resolution observations are rare. Here we report the detection of gas infall towards a cometary ultracompact H{\sc ii} region "C" in G34.26+0.15 complex. The hot core associated with "C" has a mass of $\sim$76 M_{\sun} and a volume density of 1.1$\times10^{8}$ cm$^{-3}$. The HCN (3--2), HCO$^{+}$ (1--0) lines observed by single-dishes and the CN (2--1) lines observed by the SMA show redshifted absorption features, indicating gas infall. We found a linear relationship between the line width and optical depth of the CN (2--1) lines. Those transitions with larger optical depth and line width have larger absorption area. However, the infall velocities measured from different lines seem to be constant, indicating the gas infall is uniform. We also investigated the evolution of gas infall in high-mass star forming regions. At stages prior to hot core phase, the typical infall velocity and mass infall rate are $\sim$ 1 km s$^{-1}$ and $\sim10^{-4}$ M_{\sun}\cdotyr$^{-1}$, respectively. While in more evolved regions, the infall velocity and mass infall rates can reach as high as serval km s$^{-1}$ and $\sim10^{-3}-10^{-2}$ M_{\sun}\cdotyr$^{-1}$, respectively. Accelerated infall has been detected towards some hypercompact H{\sc ii} and ultracompact H{\sc ii} regions. However, the acceleration phenomenon becomes inapparent in more evolved ultracompact H{\sc ii} regions (e.g. G34.26+0.15)

Molecular gas and triggered star formation surrounding Wolf-Rayet stars

The environments surrounding nine Wolf-Rayet stars were studied in molecular emission. Expanding shells were detected surrounding these WR stars (see left panels of Figure 1). The average masses and radii of the molecular cores surrounding these WR stars anti-correlate with the WR stellar wind velocities (middle panels of Figure 1), indicating the WR stars has great impact on their environments. The number density of Young Stellar Objects (YSOs) is enhanced in the molecular shells at $\sim$5 arcmin from the central WR star (lower-right panel of Figure 1). Through detailed studies of the molecular shells and YSOs, we find strong evidences of triggered star formation in the fragmented molecular shells (\cite[Liu et al. 2010]{liu_etal12}Comment: 1 page, IAUS29

Secondary Metabolites from the Marine Sponge Genus Phyllospongia.

Phyllospongia, one of the most common marine sponges in tropical and subtropical oceans, has been shown to be a prolific producer of natural products with a broad spectrum of biological activities. This review for the first time provides a comprehensive overview of secondary metabolites produced by Phyllospongia spp. over the 37 years from 1980 to 2016

Strategic alliances and firm value creation in China

Abstract: This study investigates the impact of 306 strategic alliances on the increment of firm value in the case of China. I apply the event study methodology using OLS market model to examine the abnormal returns of sample firms. The results show that the announcements of strategic alliance in China generate significant positive average abnormal return on the announcement date (0.96%) which reaches 1% significance level, suggesting a sizable increment in firm value by the formation of strategic alliance. The findings referring to alliance-specific characteristics are as follows: The abnormal return for firms entering policy alliance with local governments is significantly higher than the average level of abnormal return of total alliances (1.60% for policy alliances compared with 0.96% for the overall alliances on the announcement date). More specifically, the higher one government is indexed in Chinese administrative ranking, the higher abnormal return its partnering firm can achieve. As for financing alliance, the results provide evidence that the abnormal return of private firms (1.02%) is much greater than the abnormal return of state-owned enterprises (0.25%). Furthermore, there are no significant differences for abnormal returns between domestic alliances and international alliances. On considering the impact of firm-specific characteristics, the results indicate that the firm value increment by strategic alliance announcements has an inverse relationship with firm size but does not show any correlation with firm's growth opportunity. Contrast to the cases of firms in developed countries, the strategic alliances to low-tech companies contribute to increasing firm value more than the alliances to high-tech do (0.74% compared to 1.11% on the announcement date) in China. In addition, this study shows further evidence that for the firms involving alliances, the average abnormal return for private firms collaborating with state-owned partners reaches 1.15%, which is significantly positive at 1% level