Two lightning detectors, of the magnetic direction finder type, form part of a two station system for determining the position of lightning strikes. The detectors are on a baseline of approximately 600 m, and the ultimate aim of the system is to accurately detect and map lightning within a radius of 30 km. Although no real time capability is present, the archive data collected from each separate station is used to find the offset errors in the azimuthal orientation, as well as in time (using processes described in Appendix A). The relative offset errors are determined by shifting the time and azimuthal information for one station’s data and calculating the maximum possible matching records (within certain time and azimuth criteria) for each incremental shift. An analysis of the peaks in total matching records, when plotted against the relevant shift increments, is performed in order to obtain the values of the offset errors. Between the two individual stations, the relative offset in orientation is found to be 24.5 degrees, and in time to be 0.001305 days (112.75 seconds). The individual stations, as well as the triangulated data calculated from matching records, can also be calibrated using data from the South African Weather Service Lightning Detection Network (SAWSLDN). Individual station calibration indicated an offset of +6.4 degrees and 0.00575 days (496.8 seconds) for Station 1, with the offsets for Station 2 determined as +29.4 degrees and −0.000105 days (9.07 seconds). Comparison of triangulated data to SAWSLDN data yields unexpected results with regard to resultant shifts, which may point to an error or anomaly in the triangulation calculations. A detailed analysis of the storm data is contained in Appendix B of the dissertation.

<p> Under certain conditions, an induced torque measurement is a measure of the ratio of the resistivity to the square of the Hall constant. Induced torque measurements can be directly related to the connectivity of the Fermi surface.</p> <p> A modulation technique for measuring induced torque is justifield theoretically, and an instrument employing this technique is characterized. Operational limitations on parameters such as sample resistivity and modulation rate are specified. A new procedure is proposed to extract more information from induced torque measurements. This procedure would allow the measurement of resistivity and Hall constant of ellipsoidal samples. The procedure is untested but appears to be feasible.</p> <p> Observations of the induced torque of Hg3-δAsF6 show that the Fermi surface supports an open orbit in one direction. This is discussed in the context of a model (Razavi et al., 1979), which has Fermi surface cylinders of common direction. This is based on conduction in Hg chain directions, which lie in only two directions. At magnetic fields greater than 3.0 Tesla, magnetic breakdown is observed. A Brillouin zone constructed using Hg chain symmetry and crystal parameters yields reciprocal lattice vectors compatible with the observed magnetic breakdown. The model is confirmed but a refinement is needed to allow an undulation of the Fermi surface cylinders.</p> / Thesis / Master of Science (MSc)

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22077号 / 農博第2369号 / 新制||農||1072(附属図書館) / 学位論文||R1||N5231(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 近藤 直, 教授 清水 浩, 教授 飯田 訓久 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

yes / Archaeomagnetic dating offers a valuable chronological tool for archaeological investigations, particularly for dating fired material. The method depends on the establishment of a dated record of secular variation of the Earth's magnetic field and this paper presents new and updated archaeomagnetic directional data from the UK and geomagnetic secular variation curves arising from them. The data are taken from publications from the 1950's to the present day; 422 dated entries derived from existing archaeo and geomagnetic databases are re-evaluated and 487 new directions added, resulting in 909 entries with corresponding dates, the largest collection of dated archaeomagnetic directions from a single country. An approach to improving the largest source of uncertainty, the independent dating, is proposed and applied to the British Iron Age, resulting in 145 directions from currently available databases being updated with revised ages and/or uncertainties, and a large scale reassessment of age assignments prior to inclusion into the Magnetic Moments of the Past and GEOMAGIA50 databases. From the significantly improved dataset a new archaeomagnetic dating curve for the UK is derived through the development of a temporally continuous geomagnetic field model, and is compared with previous UK archaeomagnetic dating curves and global field models. The new model, ARCH-UK.1 allows model predictions for any location in the UK with associated uncertainties. It is shown to improve precision and accuracy in archaeomagnetic dating, and to provide new insight into past geomagnetic field changes. / Arts and Humanities Research Council