A generic database and spatial interface for the application of hydrological and water resource models

The paper discusses a software package that has been designed to enhance the efficiency of applying a range of hydrological and water resource simulation models. The SPATSIM (SPatial and Time Series Information Modeling) system has been developed in Delphi using MapObjects and incorporates a spatial data interface for access to the different types of information commonly associated with water resource analyses. All of the information is stored within database tables (Paradox by default) with generic structures. The structure and components of the system are briefly described and some example applications provided. The discussion identifies some of the criticisms that have been leveled at the software, the approach of the developers to user support and some possible future developments. The conclusions suggest that the development can be considered successful in that it has substantially improved the efficiency of the Institute for Water Research to undertake one of its core functions of hydrological model development and application

The origin of centennial- to millennial-scale chronological gaps in storm emplaced beach ridge plains

Recent studies of tropical cyclone surge and wave emplaced beach ridge plains have shown that these sequences often contain centennial to millennial scale gaps in their chronologies. Two explanations for the gaps exist — they are due to erosion, or alternatively a cessation or substantial slowing of depositional processes suggestive of a quieter phase in intense storm activity. Differentiating between the two is important for uncovering reliable long-term storm histories from these sequences. We use landform morphology, sediment texture and luminescence chronology to determine the origin of substantial chronological gaps in a plain containing more than 100 shore-parallel ridges composed of fine-grained sand located in northeast Australia. We identify and describe the characteristics associated with both erosional and non-erosional gaps. The erosional gaps are associated with changes in orientation between ridge sets and often a high ridge with hummocky topography that appears to have been disturbed by aeolian activity. River floods likely caused the partial erosion of ridge sets. Non-erosional gaps do not display these morphological characteristics and are likely associated with quiescence in severe tropical cyclone activity. These geomorphic and chronological signatures can be used to identify different sorts of gaps in other ridge plains and are an important tool in the reconstruction of long-term storm histories from these coastal landforms. The data also suggests that fine-grained ridges can, like their coarse-grained counterparts, be predominantly deposited by storm waves and surge and their texture need not necessarily be indicative of the processes responsible for ridge development

Influence of controlled fluid shear on nucleation rates in glycine aqueous solutions

The nucleation of glycine was investigated in supersaturated aqueous solutions exposed to well-controlled fluid shear under isothermal conditions. Shear rates between 25 s-1 and 1000 s-1 were studied using Couette and capillary flow devices. Induction times were obtained from imaging, transmission and scattering measurements, or visual monitoring. Great care was taken to eliminate any seeding in order to avoid secondary nucleation preceding formation of first crystals through primary nucleation. The observed induction times of sheared solutions were considerably lower than those of unsheared solutions. Increasing the average shear rate was found to reduce the mean induction time through a power law relationship. A detailed statistical analysis showed that the number of experimental repetitions used was sufficient to obtain statistically significant trends for the system studied. Induction times appeared to closely follow a probability distribution based on a previously published model of Jiang and ter Horst. Using their model, where the induction time is related to the rate of formation of primary nuclei and the time it takes them to grow to the size where the secondary nucleation becomes significant, it was found that both the primary nucleation rate and the growth time were strongly dependent on the shear rate imposed

Quantized representation of some nonlinear integrable evolution equations on the soliton sector

The Hirota algorithm for solving several integrable nonlinear evolution equations is suggestive of a simple quantized representation of these equations and their soliton solutions over a Fock space of bosons or of fermions. The classical nonlinear wave equation becomes a nonlinear equation for an operator. The solution of this equation is constructed through the operator analog of the Hirota transformation. The classical N-solitons solution is the expectation value of the solution operator in an N-particle state in the Fock space.Comment: 12 page

Open solar flux estimates from near-Earth measurements of the interplanetary magnetic field: comparison of the first two perihelion passes of the Ulysses spacecraft

Results from all phases of the orbits of the Ulysses spacecraft have shown that the magnitude of the radial component of the heliospheric field is approximately independent of heliographic latitude. This result allows the use of near- Earth observations to compute the total open flux of the Sun. For example, using satellite observations of the interplanetary magnetic field, the average open solar flux was shown to have risen by 29% between 1963 and 1987 and using the aa geomagnetic index it was found to have doubled during the 20th century. It is therefore important to assess fully the accuracy of the result and to check that it applies to all phases of the solar cycle. The first perihelion pass of the Ulysses spacecraft was close to sunspot minimum, and recent data from the second perihelion pass show that the result also holds at solar maximum. The high level of correlation between the open flux derived from the various methods strongly supports the Ulysses discovery that the radial field component is independent of latitude. We show here that the errors introduced into open solar flux estimates by assuming that the heliospheric field’s radial component is independent of latitude are similar for the two passes and are of order 25% for daily values, falling to 5% for averaging timescales of 27 days or greater. We compare here the results of four methods for estimating the open solar flux with results from the first and second perehelion passes by Ulysses. We find that the errors are lowest (1–5% for averages over the entire perehelion passes lasting near 320 days), for near-Earth methods, based on either interplanetary magnetic field observations or the aa geomagnetic activity index. The corresponding errors for the Solanki et al. (2000) model are of the order of 9–15% and for the PFSS method, based on solar magnetograms, are of the order of 13–47%. The model of Solanki et al. is based on the continuity equation of open flux, and uses the sunspot number to quantify the rate of open flux emergence. It predicts that the average open solar flux has been decreasing since 1987, as Correspondence to: M. Lockwood ([email protected]) is observed in the variation of all the estimates of the open flux. This decline combines with the solar cycle variation to produce an open flux during the second (sunspot maximum) perihelion pass of Ulysses which is only slightly larger than that during the first (sunspot minimum) perihelion pass