Neural Network Feedback Control: Work at UTA’s Automation and Robotics Research Institute

This is an outline of research in neural networks for feedback control done since the mid 1990s at the Automation and Robotics Research Institute (ARRI) of The University of Texas at Arlington (UTA). It shows how the developments of Intelligent Control Systems based on neural networks have followed three main generations. This statement provides a short, broad-brush perspective on the development of intelligent neural feedback controllers.     

Color vision in horses (Equus caballus): Deficiencies identified using a pseudoisochromatic plate test.

In the past, equine color vision was tested with stimuli composed either of painted cards or photographic slides or through physiological testing using electroretinogram flicker photometry. Some studies produced similar results, but others did not, demonstrating that there was not yet a definitive answer regarding color vision in horses (Equus caballus). In this study, a pseudoisochromatic plate test--which is highly effective in testing color vision both in small children and in adult humans--was used for the first time on a nonhuman animal. Stimuli consisted of different colored dotted circles set against backgrounds of varying dots. The coloration of the circles corresponded to the visual capabilities of different types of color deficiencies (anomalous trichromacy and dichromacy). Four horses were tested on a 2-choice discrimination task. All horses successfully reached criterion for gray circles and demonstration circles. None of the horses were able to discriminate the protan-deutan plate or the individual protan or deutan plates. However, all were able to discriminate the tritan plate. The results suggest that horses are dichromats with color vision capabilities similar to those of humans with red-green color deficiencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-temperature electrical characteristics of GaAs MESFETs(25-400°C)

The effects of elevated ambient and substrate temperatures (25°C up to 400°C) on the electrical characteristics of integrated GaAs MESFETs in a state-of-the-art commercial technology are reported. The focus is on the large- and small-signal parameters of the transistors. The existence of zero-temperature-coefficient drain currents is demonstrated analytically and experimentally for enhancement- and for depletion-mode GaAs MESFETs. The data show that, while GaAs MESFETs generally display degradation mechanisms similar to those of silicon MOSFETs with increasing temperature, they incur several additional effects, prominent among which are increased gate leakage currents, lowered Schottky-barrier height, decreased large- and small-signal (gate) input resistances, decreased sensitivity to sidegating and backgating up to approximately 200°C, and increased small-signal drain resistance     

Correlation between magnetic properties and the hardness of powder steels

Density and carbon content are studied for their effect on strength (hardness) and magnetic (coercive force, saturation magnetization) properties of powder steels ZhGr1 and ZhGr1D3. It is shown that the hardness of articles made of these steels may be determined indirectly by measuring two magnetic characteristics.Physicotechnical Institute, Russian Academy of Sciences, Izhevsk. Translated from Poroshkovaya Metallurgiya, Nos. 1–2, pp. 67–69, January–February, 1994.     

Yttrium sol–gel coating effects on the cyclic oxidation behaviour of 304 stainless steel

The present results reveal the interest of sol–gel coating technique to improve 304 steel high temperature oxidation resistance. An yttrium sol–gel coating appears to enhance the oxidation resistance during isothermal oxidation test, to decrease widely the oxide weight gain and to reduce the initial transient oxidation stage generally observed in the case of blank steels. Moreover, the experimental results confirm that yttrium sol–gel coating also plays a significant role on the cyclic oxidation behaviour of the 304 steel. In fact, the yttrium addition promotes remarkably the prolongation of the period during which the oxide scale still remains adherent to the substrate.     

Investigation of the Interaction of Sodium Chloride and Two Amino Sulfonic Acids,HEPES and MOPSO,by EMF Measurements

Ionic interactions in the two systems NaCl-HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) and NaCl-MOPSO (3-(N-Morpholino)-2-hydroxypropanesulfonic acid) have been studied in terms of their mutual influence on the respective activity coefficients of each component. Activity coefficients for each component of the two systems and for corresponding buffers are calculated from emf measurements of solutions containing NaCl, the aminosulfonic acid, and its conjugate base in a NalSE/solution/AgCl-Ag cell at 5, 15, 25, and 37 °C.     

Starch–poly(ethylene-co-acrylic acid) composite films. Effect of processing conditions on morphology and properties

Formulations containing 4 parts cornstrach, 5 parts poly(ethylene-co-acrylic) (EAA), 1 part urea, and 1.6 parts of either water or aqueous ammonia were extruded at either 110–120°C or 150–160°C; and the resulting extrudates were then extrusion-blown into films. Complex formation between EAA and starch was measured by either X-ray diffraction or by solvent extraction of uncomplexed EAA. Although the processing temperature had only a minor effect on the amount of EAA complexed by starch, use of aqueous ammonia rather than water in these formulations increased the amount of complexed EAA by about a factor of 2. In films prepared with aqueous ammonia, the polysaccharide phase was present as submicron-sized domains. When ammonia was omitted from these formulations, the polysaccharide phase was less uniform in size and contained particles that were over an order of magnitude larger than those observed with ammonia.     

Theoretical study of a potential low-noise semimetal-basedavalanche photodetector

The authors present a theoretical analysis of a possible avalanching photodetector (APD)-based on II-VI compound semiconductors. Each unit cell is composed of a HgTe layer, or a similar semimetal, sandwiched between two layers of CdTe and HgCdTe or similar semiconducting materials. The barrier layers are graded so that the leading barrier height is just high enough to eliminate the thermionic emission dark current out of the well. The use of a semimetal within the well has a distinct advantage over a semiconductor, which is that the ionization process is essentially an interband mechanism since the confined carriers within the well lie within the overlapping conduction and valence bands. As a result, the concentration of target carriers is virtually inexhaustible as in a conventional interband device