16,658 research outputs found
First ERTS-1 results in southeastern France: Geology, sedimentology, pollution at sea
Results obtained by four ERTS projects in southeastern France are summarized. With regard to geology, ERTS photos of Western Alps are very useful for tectonic interpretation because large features are clearly visible on these photographs even though they are often hidden by small complicated structures if studied on large scale documents. The 18-day repetition coverage was not obtained, and time-varying sedimentological surveys were impossible. Nevertheless, it was possible to delineate the variations of the shorelines in the Rhone Delta for a period covering the least 8,000 years. Some instances of industries discharging pollutant products at sea were detected, as well as very large anomalies of unknown origin. Some examples of coherent optical processing have been made in order to bring out tectonic features in the Alps mountains
Pointing/roll mechanism for the ultraviolet coronagraph spectrometer
A pointing/roll mechanism for the Ultraviolet Coronagraph Spectrometer (UVCS) is presented along with a description of the mechanism control algorithm. The mechanism, operating in space, will position the 2.1 meter long, 0.7 meter diameter UVCS instrument in pitch and yaw, within a 54 arc-minute half angle cone, and will also allow it to rotate + or - 179.75 deg. After considerable design effort, an optimum mechanical solution was achieved, which meets all scientific requirements as well as weight, volume, and power budgets. Evolution of the mechanism is presented along with the design status
The Primary Pretenders
We call a composite number q such that there exists a positive integer b with
b^p == b (mod q) a prime pretender to base b. The least prime pretender to base
b is the primary pretender q_b. It is shown that there are only 132 distinct
primary pretenders, and that q_b is a periodic function of b whose period is
the 122-digit number
19568584333460072587245340037736278982017213829337604336734362-
294738647777395483196097971852999259921329236506842360439300.Comment: 7 page
Phase space shifts in command structures in networked systems
This paper presents the rationale behind an important enhancement to the NATO SAS-050 approach space, combined with empirical results which take advantage of these enhancements. In Part 1 a new theoretical legacy for the NATO model is presented. This legacy inspires a number of developments which allow live data to be plotted into it, and we demonstrate that the model is well able to discriminate between alternative C2 structures. Part 2 illustrates this feature with multinational data from the ELICIT community. It is surprising to see that teams in both C2 and Edge conditions operate in broadly the same area of the phase space cube. The structure of the pre-ordained ELICIT ‘classic C2’ hierarchy and the deterministic nature of the shared task are put forward as explanations for this, and as future enhancements to the ELICIT paradigm
A simple reactive-transport model of calcite precipitation in soils and other porous media
Calcite formation in soils and other porous media generally occurs around a localised source of reactants, such as a plant root or soil macro-pore, and the rate depends on the transport of reactants to and from the precipitation zone as well as the kinetics of the precipitation reaction itself. However most studies are made in well mixed systems, in which such transport limitations are largely removed. We developed a mathematical model of calcite precipitation near a source of base in soil, allowing for transport limitations and precipitation kinetics. We tested the model against experimentally-determined rates of calcite precipitation and reactant concentration–distance profiles in columns of soil in contact with a layer of HCO3−-saturated exchange resin. The model parameter values were determined independently. The agreement between observed and predicted results was satisfactory given experimental limitations, indicating that the model correctly describes the important processes. A sensitivity analysis showed that all model parameters are important, indicating a simpler treatment would be inadequate. The sensitivity analysis showed that the amount of calcite precipitated and the spread of the precipitation zone were sensitive to parameters controlling rates of reactant transport (soil moisture content, salt content, pH, pH buffer power and CO2 pressure), as well as to the precipitation rate constant. We illustrate practical applications of the model with two examples: pH changes and CaCO3 precipitation in the soil around a plant root, and around a soil macro-pore containing a source of base such as urea
Oxford and Cambridge Boat Race: Performance, Pacing and Tactics Between 1890 and 2014
Background: Currently no studies have examined the historical performances of Oxford and Cambridge Boat Race crews in the context of performance, pacing and tactics which is surprising as the event has routinely taken place annually for over 150 years on the same course. Objectives: The purpose of this study was twofold, to firstly examine the historical development of performances and physical characteristics of crews over 124 years of the Oxford and Cambridge Boat Race between 1890 and 2014 and secondly to investigate the pacing and tactics employed by crews over that period. Methods: Linear regression modelling was applied to investigate the development of performance and body size for crews of eight male individuals over time from Boat Race archive data. Performance change over time was further assessed in 10-year clusters while four intra-race checkpoints were used to examine pacing and tactics. Results: Significant correlations were observed between performance and time (1890–2014) for both Oxford (r = −0.67; p < 0.01) and Cambridge (r = −0.64; p < 0.01). There was no difference in mean performance times for Oxford (1170 ± 88 s) and Cambridge (1168 ± 89.8 s) during 1890–2014. Crew performance times improved over time with significant gains from baseline achieved in the 1950s (Cambridge) and the 1960s (Oxford), which coincided with significant change in the physicality of the competing crews (p < 0.01). There was no tactical advantage from commencing on either the Surrey or Middlesex station beyond chance alone; however, all crews (n = 228) adopted a fast-start strategy, with 81 % of victories achieved by the crew leading the race at the first intra-race checkpoint (24 % of total distance). Crews leading the race at the final checkpoint (83 % of total distance; 1143 m) achieved victory on 94 % of occasions. Conclusion: Performances and physical characteristics of the crews have changed markedly since 1890, with faster heavier crews now common. Tactically, gaining the early lead position with a fast-start strategy seems particularly meaningful to success in the Boat Race throughout the years, and has been of greater importance to race outcome than factors such as the starting station
The pulsed air gust generator Final report
Wind tunnel simulation of jet pulsing apparatus for controlled gust
AGGREGATE STABILITY AND WATER RETENTION NEAR SATURATION CHARACTERISTICS AS AFFECTED BY SOIL TEXTURE, AGGREGATE SIZE AND POLYACRYLAMIDE APPLICATION
Understanding the effects of soil intrinsic properties and extrinsic conditions on aggregate stability is essential for the development of effective soil and water conservation practices. Our objective was to evaluate the combined role of soil texture, aggregate size and application of a stabilizing agent on aggregate and structure stability indices (composite structure index [SI], the and n parameters of the VG model and the S-index) by employing the high energy (0-5.0 J kg(-1)) moisture characteristic (HEMC) method. We used aggregates of three sizes (0.25-0.5, 0.5-1.0 and 1.0-2.0 mm) from four semi-arid soils treated with polyacrylamide (PAM). An increase in SI was associated with the increase in clay content, aggregate size and PAM application. The value of increased with the increase in aggregate size and with PAM application but was not affected by soil texture. For each aggregate size, a unique exponential type relationship existed between SI and . The value of n and the S-index tended, generally, to decrease with the increase in PAM application; however, an increase in aggregate size had an inconsistent effect on these two indices. The relationship between SI and n or the S-index could not be generalized. Our results suggest that (i) the effects of PAM on aggregate stability are not trivial, and its application as a soil conservation tool should consider field soil condition, and (ii), n and S-index cannot replace the SI as a solid measure for aggregate stability and soil structure firmness when assessing soil conservation practices
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