State and Output Feedback Certainty Equivalence M‐MRAC for Systems with Unmatched Uncertainties

The paper presents a certainty equivalence indirect adaptive control design method for parametric strict feedback nonlinear systems of any relative degree with unmatched uncertainties in state and output feedback settings. The approach is based on the parameter identification (estimation) model, which is completely separated from the control design and is capable of producing parameter estimates as fast as the computing power allows. It is shown that the system's input and output tracking errors can be systematically decreased by the proper choice of the design parameters.     

Robust uniform triangulation algorithm for computer aided design

This paper presents a new robust uniform triangulation algorithm that can be used in CAD/CAM systems to generate and visualize geometry of 3D models. Typically, in CAD/CAM systems 3D geometry consists of 3D surfaces presented by the parametric equations (e.g. surface of revolution, NURBS surfaces) which are defined on a two dimensional domain. Conventional triangulation algorithms (e.g. ear clipping, Voronoi-Delaunay triangulation) do not provide desired quality and high level of accuracy (challenging tasks) for 3D geometry. The approach developed in this paper combines lattice tessellation and conventional triangulation techniques and allows CAD/CAM systems to obtain the required surface quality and accuracy. The algorithm uses a Cartesian lattice to divide the parametric domain into adjacent rectangular cells. These cells are used to generate polygons that are further triangulated to obtain accurate surface representation. The algorithm allows users to control the triangle distribution intensity by adjusting the lattice density. Once triangulated, the 3D model can be used not only for rendering but also in various manufacturing and design applications. The approach presented in this paper can be used to triangulate any parametric surface given in S(u,v) form, e.g. NURBS surfaces, surfaces of revolution, and produces good quality triangulation which can be used in CAD/CAM and computer graphics applications.     

Perceptual sharpening in the developing rat.

Studied the development of perceptual sharpening in 4 experiments with 514 Sprague-Dawley rats using the heart rate orienting response ([HROR] marked cardiac deceleration to novel stimuli) as the dependent measure. Preweanling Ss either 16–17 or 19–20 days of age were habituated to a 1,600-Hz tone over 15 trials. On Trial 16, the stimulus frequency was changed to 1 of 7 tones distributed on either side of the habituated stimulus. Analysis of the HROR showed that 16–27 day old Ss failed to respond to any of the new frequencies, which indicated generalization of habituation to the auditory stimuli within the frequency range studied. In marked contrast, 19–20 day old Ss displayed an HROR proportional to the difference between the habituated and the test stimuli. These age-related differences were not due to differences in sensitivity to the test stimuli, effector fatigue, or inability to discriminate between the test stimuli. Results indicate that perceptual sharpening develops relatively rapidly in rats and that perceptual sharpening, stimulus detection, and stimulus discrimination follow separate ontogenetic time courses. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reduction of ontogenetic retention decrements in rats by pretraining stressful experiences.

Five experiments with 130 Holtzman rats demonstrated that pretraining stressful experiences, either similar to or qualitatively different from the conditioning UCS, reduced ontogenetic retention decrements without directly influencing response acquisition. Ss that received pretreatment with footshock, hypothermia, or restraint on Days 16, 17, and 18 of age showed substantially improved long-term retention of conditioned fear learned at 20 days of age. It was also found that preshock enhanced retention of both an appetitive approach response and punishment of the approach response. These experiments involving extinction and undertraining manipulations indicate that the facilitation of retention was not directly attributable to acquisition strength. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and habituation of the heart rate orienting response to auditory and visual stimuli in the rat.

Studied development and habituation of responsivity to sound and visual stimuli in 120 8–19 day old Sprague-Dawley pups by using a change in heart rate (HR) as the indicant response (Exp I). A change in HR to sound (white noise) first occurred around 14–25 days of age and was acceleratory in nature. Within 3 days, the direction of the HR response shifted to bradycardia. The HR response to light was also characterized by tachycardia in young pups (14 days), which shifted to bradycardia as the pups matured (16 days and older). In Exp II, the HR response of 15- and 19-day-old Ss was studied at 3 auditory stimulus intensities (60, 70, and 90 db, B scale). Stimulus intensity influenced the magnitude of the cardiac response in the 19-day-old pups. Data suggest that even weak sensory stimuli elicited a defensive reaction (HR acceleration) during the 1st few days that followed onset of function in each sensory system; later in development, the same stimulus elicited an orienting response (cardiac deceleration). (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

X-ray Diffraction Investigations of Microstructure of Calcium Hydroxide Crystallites in the Interfacial Transition Zone of Concrete

This work presents theoretical and experimental X-ray diffractometry investigations of the morphology and deformation state of calcium hydroxide (Ca(OH)₂, CH) crystallites in the interfacial transition zone of concrete. Based on the developed theoretical approach, the distributions of CH crystallites and their coherent domains over strains and sizes are reconstructed. The average amounts of planar defects, cracks, and possible stacking faults within a CH crystallite are estimated. A comparative analysis is conducted for the morphology of CH texture depending on the type of aggregate particles (granite and smoky quartz) used.     

Robust adaptive observer design for uncertain systems with bounded disturbances.

This paper presents a robust adaptive observer design methodology for a class of uncertain nonlinear systems in the presence of time-varying unknown parameters with absolutely integrable derivatives, and nonvanishing disturbances. Using the universal approximation property of radial basis function (RBF) neural networks and the adaptive bounding technique, the developed observer achieves asymptotic convergence of state estimation error to zero, while ensuring boundedness of parameter errors. A comparative simulation study is presented by the end.