Remote sensing in Iowa agriculture: Identification and classification of Iowa's crops, soils and forestry resources using ERTS-1 and complimentary underflight imagery

There are no author-identified significant results in this report

Limit cycles in the presence of convection, a travelling wave analysis

We consider a diffusion model with limit cycle reaction functions, in the presence of convection. We select a set of functions derived from a realistic reaction model: the Schnakenberg equations. This resultant form is unsymmetrical. We find a transformation which maps the irregular equations into model form. Next we transform the dependent variables into polar form. From here, a travelling wave analysis is performed on the radial variable. Results are complex, but we make some simple estimates. We carry out numerical experiments to test our analysis. An initial `knock' starts the propagation of pattern. The speed of the travelling wave is not quite as expected. We investigate further. The system demonstrates distinctly different behaviour to the left and the right. We explain how this phenomenon occurs by examining the underlying behaviour.Comment: 20 pages, 5 figure

Generation of finite wave trains in excitable media

Spatiotemporal control of excitable media is of paramount importance in the development of new applications, ranging from biology to physics. To this end we identify and describe a qualitative property of excitable media that enables us to generate a sequence of traveling pulses of any desired length, using a one-time initial stimulus. The wave trains are produced by a transient pacemaker generated by a one-time suitably tailored spatially localized finite amplitude stimulus, and belong to a family of fast pulse trains. A second family, of slow pulse trains, is also present. The latter are created through a clumping instability of a traveling wave state (in an excitable regime) and are inaccessible to single localized stimuli of the type we use. The results indicate that the presence of a large multiplicity of stable, accessible, multi-pulse states is a general property of simple models of excitable media.Comment: 6 pages, 6 figure

Technology Development in Water Resource Management

In developed nations, technological advancements rapidlyare changing every aspect of our lives: how we work, howwe communicate with each other, and even how we areentertained. The influence of technology is readilyapparent. The subtleties of technology and its lessapparent influences also are tremendous. Advances incomputer technology, communications, and manufacturingare affecting all sectors, including engineering. In thearena of water resources, technological advances havehelped to not only develop a better understanding of ourphysical systems but have allowed improved operationaland institutional tools to be developed to support watermanagement. These advances have the potential toprovide large and meaningful benefits to less developedinfrastructures.The objective of this paper will be to describe severaltechnological advances in water resources, specifically inareas such as Flood Warning, Water Administration, andMulti-Objective Water Management. Examples oftechnologies implemented which have direct applicabilityto developing infrastructures are described. Important tothe discussion of these advances are the ways in whichimplementation and use of these technologies can protectand save lives, extend and optimally use limited resources,and provide useful inform ation to assist in the sustainab legrowth and development of our natural resources

The cloud-in-cloud problem for non-Gaussian density fields

The cloud-in-cloud problem is studied in the context of the extension to non-Gaussian density fields of the Press-Schechter approach for the calculation of the mass function. As an example of a non-Gaussian probability distribution functions (PDFs) we consider the Chi-square, with various degrees of freedom. We generate density fields in cubic boxes with periodic boundary conditions and then determine the number of points considered collapsed at each scale through an hierarchy of smoothing windows. We find that the mass function we obtain differs from that predicted using the Extended Press-Schechter formalism, particularly for low values of $\sigma$ and for those PDFs most distinct from a Gaussian.Comment: 5 pages, LaTex using mn.sty, matches published version, results for the Inverted Chi-square distribution withdraw

Expanding direction of the period doubling operator

We prove that the period doubling operator has an expanding direction at the fixed point. We use the induced operator, a ``Perron-Frobenius type operator'', to study the linearization of the period doubling operator at its fixed point. We then use a sequence of linear operators with finite ranks to study this induced operator. The proof is constructive. One can calculate the expanding direction and the rate of expansion of the period doubling operator at the fixed point