LASIG II - Pulsed laser ion generator study Final report

Ion current produced by illuminating materials with focused output of pulsed ruby lase

The combustion characteristics and stable carbon isotopic compositions of irradiated organic matter: implications for terrestrial and extraterrestrial sample analysis

Exposure to ionizing radiation causes the mean combustion temperature of naturally occurring, solid, terrestrial organic matter, derived from the radiation-induced polymerization of methane, to increase

The Behavior of Soluble Salt in Sharkey Clay

Soluble salt problems do exist and are significant in Arkansas. Studies have been conducted on Crowley silt loam (Typic Albaqualfs) which have established the behavior of soluble salt in that soil. The major objective of this study was to quantify the behavior of soluble salt in a second important Mississippi River Delta soil - the Sharkey (Vertic Haplaquepts). To this end, estimation of the downward redistribution of salt and the estimation of various components of the water balance for this soil served as specific objectives. Field studies were designed to monitor the movement of salt in the Sharkey soil and to characterize selected components of the water balance. In total, three tentative conclusions may be drawn from the data. First, the infiltration for the Sharkey soil was approximately three times that of the Crowley silt loam. The average value was 29 cm for the rice season. Second, levee seepage, while significant for small plots, was shown to be small for production-sized fields. Levee seepage remained relatively constant throughout the season and averaged 0.025 nvfym/d. And third, downward redistribution of salt was large and appeared to follow a pattern where a peak occurred at the surface and, possibly, at the lower soil depths

An investigation into the effect of sweat and moisture on the performance of in-ear monitors

In-ear monitors are used widely in the live event industry, allowing performers precision control of their personal monitoring system while suppressing interference from the external environment. This paper presents the results of an experiment on the effect of moisture, primarily sweat, on the acoustical output of in-ear monitor transducers. A 3D model of a test subject’s ear was constructed with custom moulded in-ear monitors inserted. Electroacoustic testing was carried out at various sound levels with an artificial sweat solution applied to the model. Results indicate that moisture has the potential to enter the ear canal due to capillary action, affecting the listening experience in terms of frequency response and overall level. Recommendations are provided based on this research, pointing to further necessary investigations

Simplified methods of assessing the impact of grid frequency dynamics upon generating plants

The frequency of the national electricity grid is affected by fluctuations in supply and demand, and so continually "judders" in an essentially unpredictable fashion around 50 Hz. At present such perturbations do not seemingly affect Nuclear Electric as most of their plant is run at more or less constant load, but they would like to be able to offer the national grid a mode of operation in which they "followed" the grid frequency: i.e., as the frequency rose above or fell below 50 Hz, the plant's output would be adjusted so as to tend to restore the frequency to 50 Hz. The aim is to maintain grid frequency within 0.2 Hz of its notional value. Such a mode of operation, however, would cause a certain amount of damage to plant components owing to the consequent continual changes in temperature and pressure within them. Nuclear Electric currently have complex computational models of how plants will behave under these conditions, which allows them to compute plant data (e.g., reactor temperatures) from given grid frequency data. One approach to damage assessment would require several years'-worth of real grid data to be fed into this model and the corresponding damage computed (via "cycle distributions" created by their damage experts). The results of this analysis would demonstrate one of three possibilities: the damage may be acceptable under all reasonable operating conditions; or it may be acceptable except in the case of an exceptional abrupt change in grid frequency (caused by power transmission line failure, or another power station suddenly going off-line, for instance), in which case some kind of backup supply (e.g., gas boilers) would be required; or it may simply be unacceptable. However, their current model runs in approximately real time, making it inappropriate for such a large amount of data: our problem was to suggest alternative approaches. Specifically, we were asked the following questions: - Can component damage be reliably estimated directly from cycle distributions of grid frequency? i.e., are there maps from frequency cycle distributions to plant parameter cycle distributions? - Can a simple model of plant dynamics be used to assess the potential for such maps? - What methods can be used to select representative samples of grid frequency behaviour? - What weightings should be applied to the selections? - Is it possible to construct a "cycle transform" (Fourier transform) which will capture the essential features of grid frequency and which can then be inverted to generate simulated frequency transients? We did not consider this last question, other than to say "probably not". We were supplied with data of the actual grid frequency measurements for the evening of 29/7/95, and the corresponding plant responses (obtained using Nuclear Electric's current computational model). A simplified nonlinear mathematical model of the plant was also provided. Two main approaches were considered: statistical prediction and analytical modelling via a reduction of the simplified plant model

‘The sword that was broken …’: the detection of recycled iron in the archaeological record

Although the recycling of materials such as copper and glass is widely known and generally well understood within archaeological contexts, far less is known about the recycling of iron. Iron recycling is more complex than that of other metals for two reasons. First, normal manufacturing processes, which include forging several components to make a composite object, offer the opportunity to include recycled iron. Second, the material itself is more complex than Cu alloys. The alloys of Fe, depending primarily on C content, are very different in terms of properties and can be interconverted by (normally) removing C such as decarburizing cast iron to make wrought iron. Thus, recycling practices are potentially intimately combined with such processes. These factors, combined with the poor preservation of archaeological iron and the consequent reluctance to carry out extensive studies (which often require destructive analysis via metallography), mean that there are no clear criteria for identifying recycled iron. However, limited historical documentation suggests, at least indirectly, that such recycling was common. This paper is neither comprehensive nor definitive, but merely intends to promote discussion and awareness of iron recycling by hypothesizing several possible mechanisms and providing a few illustrative archaeological examples