Sensitivity analysis of initial value problems with mixed odes and algebraic equations

An efficient method is described for sensitivity analysis of nonlinear initial value problems, which may include algebraic equations as well as ordinary differential equations.The linearity of the sensitivity equations is utilized to solve them directly via the local Jacobian of the state equations. The method is implemented with the implicit integrator DASSL and is demonstrated on a stiff industrial reaction model.     

Cortical implants for the blind

Arrays of stimulating electrodes can be placed in the brain itself, in the visual cortex, to bring vision to the profoundly blind. However, when designing such devices one needs to take into consideration the fact that the visual pathway maps images onto cortical structures in a complex and unpredictable way     

Contributions of Transformation and Microcracking to the Plastic Deformation of Magnesia-Partially-Stabilized Zirconia

The measured plastic deformation of Mg-PSZ under stress contains contributions from both transformation and microcracking. A method is described to separate the contributions from transformation and microcracking for samples deformed in uniaxial tension. Such a separation enables the ratio of the longitudinal to transverse strains arising from the transformation to be estimated. The results are compared to the predictions of the shear–dilatation model of Chen and Reyes-Morel. Serious discrepancies are found between the experimental results and the predictions of the model and the possible reason for this is discussed.     

Simulation of programmable logic controller

The development and test of a PLC control program takes time, increases equipment down-time, and might damage hardware due to program errors. All of these problems can be eliminated if there is a computer simulation system for testing control programs off line. This paper presented a new method, called Direct Sequential Method, for simulating PLCs. This method resolves a ladder logic sequentially by applying a series of logic deductions. This simulation system has been implemented in C and tested successfully.     

Polyacrylic acid macromolecule—complexed zinc phosphate crystal conversion coatings

When water-soluble polyacrylic acid (PAA) macromolecules are introduced into zinc phosphating liquids, significant improvements in the yield of conventional zinc phosphate conversion films deposited on carbon steel surfaces are obtained. The improvements include controllability of crystal dimensions, degree of crystallinity, and coating weight. The conversion layer formed is a composite microstructure consisting of a bulk PAA polymer and complexed PAA continuously overlaying a uniform array of fine dense zinc phosphate crystals. Interfacial studies of the composite layer using infrared spectroscopy, energy-dispersive X-ray spectrometry associated with scanning electron microscopy, and X-ray photoelectron spectroscopy indicated that the functional carboxylic acid groups in the PAA molecules were strongly chemisorbed by the Zn atoms at the outermost surface sites of the crystal layers. The intermolecular bridging action of the surface Zn atoms which connect the PAA and the zinc phosphate crystal layers results in good adhesion at the PAA–crystal interfaces. In addition, the plasticized complex formation plays an essential role in increasing the stiffness and the ductility of the normally conventional crystal films. The flexibility of the complex coating surface and the thickness and surface roughness of the thin PAA overlayer all affect the adhesive force at the interface between the organic polymer topcoat and the complexed coating.