| As an introduction to the detailed information given in the following chapters, I give here an overview of the research work I carried out during the period from June 2002 to June 2004 at Shanghai Astronomical Observatory.Principal research projects1. The largest part of my time was spent on preparation of the paper "On Constraining the SPH Kernel Radius in Galaxy Simulations", Williams, Churches, Nelson, 2004, ApJ, 607, 1-19. A short form summary of the results of this paper are given in chapter 1.2. The second research project was an investigation of numerical accuracy in galaxy simulations. More than 120 numerical simulations were carried out using the SUN parallel computer at Cardiff University, UK, in collaboration with Dr. A. H. Nelson. These results are currently under preparation for submission in the form of two papers. A brief summary of some of these results is given in chapter 2.3. While attending the IAU general assembly in Sydney during July of 2004 I struck up a collaboration with Prof. T. Matsuda of the Earth Sciences Department of Kobe University. Using the SUN parallel computer at Kobe, and the GRAPE computers of the Japanese Centre for Computational Astrophysics, we decided to work on simulations of the Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud. I have visited Kobe twice, attended a meeting on computational astrophysics, and given a number of talks and seminars under this collab-oration. The research project is ongoing, and some of aspects of our recent progress are discussed in chapter 34. In collaboration with Dr. Nelson, I have investigated the formation and structure of the dwarf galaxies which naturally occur in our simulations of grand-design spiral galaxies. Our results give support to the hypothesis that a large fraction of the dark matter in dwarf galaxies is molecular hydrogen. Preliminary results were published in the proceedings of IAU220: Dark matter in galaxies, and we have submitted these results in full to Nature.5. From January 1999 to March 20011 worked in the MPG Albert Einstein Institute for Gravitational Physics in Golm, Germany, on algorithms for the detection of gravitational waves from neutron stars. At that time, the GEO600 and LIGO gravitational wave detectors were still only at the stage of construction and early testing. However, in 2002 the first quality data was taken, and during the past two years a series of papers have been published by the gravitational wave teams, some of which use the algorithms which I helped to develop. See the list of publications below.Supplementary projects and tasks1. Under the direction of Prof. Chenggang Shu I helped to write the successful application for funding from the IAU for our conference IAUC199: Probing the universe through quasar absorption lines, to be held in late March 2005 at SHAO.2. In collaborations with Prof. Matsuda of Kobe University and Dr. Nelson of Cardiff University, a number of graduate students have used my galaxy formation code in short research projects. This code is written to run on parallel computers, and solves the equations of motion for gas. stars, and dark matter using the Treecode and SPH techniques. An algorithm to follow the conversion of gas into stars is also included. Due to the complexity in using such a code, it became necessary toprovide comprehensive documentation, such that students could learn for themselves how to use the code and understand the algorithms. With this purpose in mind, a detailed user guide was written, given in appendix A. This has allowed graduate students to quickly become familiar with the process of carrying out galaxy simulations, and make quick progress in their research projects.3. In a collaboration with Drs. Davies and Nelson at Cardiff University and their PhD student, I have begun work on the study of dwarf galaxy formation. The ISM and star formation are critical processes in the formation of a dwarf galaxy, because matter in such galaxies is less bound relative to that in larger galaxies. In order to study these effects...
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