Search Results
You are looking at 1 - 10 of 14 items for
- Author or Editor: D. Hall x
- Refine by Access: All Content x
Abstract
This paper is the third in a series on the flows of influence at the interface between geoscience research and the exploration for and mining of nuclear fuels. It deals with the application of signal processing methods to research and industry indicators, with emphasis on time and frequency domain correlations and lags, and on growth modelling of the indicators using the special and general logistic models. The findings include the following: there was a strong interchange across the science-industry interface; quantitative methods can establish the degree of correlation and the time periods in which these correlations mainly reside; also the timing of decisions to initiate exploration and research can be specified in this case. A strategy of applying quantitative methods, history of science, and periodic analyses of the state of the industry to studies of science policy is suggested by this research.
Abstract
Petroleum production and exploration, used as petroleum industry indicators, and accumulation of petroleum-related geoscience literature, used as a science indicator, were compared by several means to gauge the degree of interaction between science and the industry in the period 1934–1990. Methods of comparison employed were: time domain correlations and crosscorrelation; correlations of spectra using coherence and crosspower spectra, and growth-modelling of the indicators. A fifty-year exploration cycle was found, beginning about 1945. Principal features of this cycle seem to coincide with prominent features in the time series for geoscience literature, and both of these variables are correlated with petroleum production. All three variables appear to have been determined ultimately by economic and political events which affected the petroleum industry. All of them show long-period cycles which coincide with the fourth Kondratiev cycle and the beginning of the fifth Kondratiev. The longest time series used (petroleum production in the United States, 1860–1990) shows long-period cycles matching the third, fourth and fifth Kondratiev cycles.
Abstract
The earth and planetary sciences have shown remarkable changes during the present century. The relative coverage of earth and earth-planetary science in the journalScience (from the USA) was studied quantitatively at 5-year intervals for the period 1900–1976. Similar data, but more widely spaced, (10-year intervals) were obtained from the journalNature (from Great Britain) as corroboration.It was found in both journals that the relative attention given to earth science and to the combination of earth and planetary sciences dropped through the century to a low point about 1955. Thereafter the trend reversed, with both of these elements rising almost twice as rapidly as they had previously fallen. A comparison with previous work on the production of American periodical literature showed similar trends but a consistently greater proportion of coverage of these subjects inScience than that in the literature, suggesting that the former is reflecting a wider spectrum of impact of these subjects than is the latter. General science journals may be a better indicator of impact of a science than is the specialized literature.The similarity of results in the two journals indicates that the idea of patterns in world science is a valid one, in which the USA and Great Britain belong to a common pattern.
Abstract
The nuclear industry was used as a case history to examine the influences between science and industry. The nuclear resources aspect of the industry was chosen for study. A correlation is found among indicators of geoscience research, exploration for uranium ores, production of uranium, and the general state of the industry. Some of the science-industry interfaces were identified as fruitful areas for further study, and a historical analysis of exploration technology shows that a scientific development engendered by the requirements of an early phase of the industry was key to later expansion in exploration and resources discovery.
Abstract
Computerized bibliographic databases have become sufficiently well developed and widely available to researchers that they have become potentially an important source of time series estimates of the growth of scientific literature. This paper uses the GEOREF3 database in such an application to estimation of the growth of geoscience. It is found by comparison with studies previously done from the hardcopy equivalents of GEOREF3 that the computer-derived time series can achieve results similar to their equivalents and do this more efficiently, more inexpensively and more comprehensively. Examples are given for geoscience as a whole, and for the literature related to several mineral commodities: iron ore, lead ore, nickel ore, petroleum and natural gas, radioactive minerals and ores, and zinc ore.
Abstract
The interactions between experimental discoveries in low-energy nuclear fission and our theoretical understanding of the structure of the nucleus are reviewed. The history of this synergistic relationship begins with the discovery of fission, the development of the liquid-drop model and the experimental evidence for magic numbers, continues through the development of the shell model, the experimental discovery of shape isomerism, the double-humped fission barrier resulting from theoretical calculations of shell corrections to the liquid-drop model, the spontaneous fission half-life disaster, the discovery of symmetric mass division in spontaneous fission and theoretical treatments based on different paths to scission. It concludes with a brief review of our current experimental and theoretical understanding of low-energy fission and the prospects for future developments.
Abstract
Inductively coupled plasma mass spectrometry (ICP-MS) was evaluated for major, minor, trace, and ultra-trace elemental analyses of individual tree rings. The samples were obtained from an old-growth Douglas fir (Pseudotsuga menziesii) growing 15 km northeast of Mount St. Helens volcano, Washington, USA and from trees at various other North American sites. Samples were brought into solution by microwave digestion in sealed Teflon vessels. Eightly percent of elements from Li to U had detection limits in the solid (wood) below 8.0 ng g–1 (parts per billion, ppb). When selected element concentrations in the Mount St. Helens samples are plotted against time, two anomalous peaks occur at A. D. 1478 and 1490 that closely correlate with past eruptions of the volcano. These preliminary results show that ICP-MS is a rapid and sensitive analytical method for multielemental analyses of individual tree rings.
Abstract
Lead zirconate titanate (PZT) ceramic powder has been synthesized from metal nitrate solutions using the EDTA-gel method with different nitric acid/EDTA ratios. It was found that the thermal decomposition of the precursor was strongly affected by the nitric acid/EDTA ratio, the amount of sample, the atmosphere, and the heating rate. Crystallization of the perovskite PZT phase initiated at external temperatures as low as 250°C, as a result of the exothermic decomposition reaction of the nitrate-EDTA complexes. Possible reaction schemes are suggested and discussed to describe the thermal decomposition of PZT-EDTA precursors under different experimental conditions.
Abstract
Nuclear forensic science has become increasingly important for global nuclear security. However, many current laboratory analysis techniques are based on methods developed without the imperative for timely analysis that underlies the post-detonation forensics mission requirements. Current analysis of actinides, fission products, and fuel-specific materials requires time-consuming chemical separation coupled with nuclear counting or mass spectrometry. High-temperature gas-phase separations have been used in the past for the rapid separation of newly created elements/isotopes and as a basis for chemical classification of that element. We are assessing the utility of this method for rapid separation in the gas-phase to accelerate the separations of radioisotopes germane to post-detonation nuclear forensic investigations. The existing state of the art for thermochromatographic separations, and its applicability to nuclear forensics, will be reviewed.
Abstract
Raw chemicals such as metal nitrates and chlorides were found to affect the thermal decomposition behaviour of EDTA-gel precursors used for the production of ceramic powders. Fine, homogeneous ceramic powders were produced from nitrate solutions while chlorides gave segregated phases. In studies on the production of lead zirconate titanate (PZT) using chlorides, the segregation and loss of lead was observed and shown to be caused by the formation and evaporation of PbCl2. Thermal analysis (DTA/TG) quantitatively proved the suggested reaction mechanism for this phase segregation. Crystallization of the desired perovskite phase of lead zirconate titanate (PZT) and barium titanate (BT) initiated at temperatures as low as 250°C in the nitrate-EDTA precursors. Water of crystallization and formation of BaCO3 in the barium titanate precursor were suggested to account for differences in the observed decompositional behaviours of the BT and PZT precursors.
