Multi‐Objective Cost‐Detectability in Unfalsified Adaptive Control

Vector‐valued controller cost functions that are solely data‐dependent and reflect multiple objectives of a control system are examined within the framework of unfalsified adaptive control. The notion of Pareto optimality of vector‐valued cost functions and the conditions under which they are cost‐detectable are discussed. A sampled data/discrete‐time Level‐Set controller switching algorithm is investigated which allows for the relaxation of the assumption that the controller cost function be monotonically nondecreasing in time. This opens up the possibility of the use of fading memory cost functions which are nonmonotone. When an active controller is falsified at the current threshold cost level, the Level‐Set switching algorithm replaces it by an effectively unique solution of the weighted Tchebycheff method, thus ensuring the selection of an unfalsified Pareto optimal controller. Theoretical results for convergence and stability of the adaptive system are given. Simulation results validate the use of cost‐detectable multi‐objective cost functions. An example of a cost‐detectable cost function which uses fading memory norm of the fictitious tracking error as a performance measure is shown. This allows for computation of performance of nonactive controllers with respect to a reference model.     

Biogenic Factors of Radionuclide Immobilization on Sandy Rocks of Upper Aquifers

Radiochemistry - The effect of microorganisms on immobilization of Cs, Sr, U, and Tc on sandy rocks from upper aquifers was studied. Aquifer water samples taken from observation boreholes in the...     

Hydrophobic properties of a fluoropolymer film covering gold nanoparticles

Thin fluoropolymer films were deposited on gold nanoparticles with different diameters by the hot-wire chemical-vapor-deposition method. The contact angles of wetting of samples with water and CH₂I₂ were determined using a DSA-100 KRUSS device, and the free surface energy of the coated surface was also determined. The influence of encapsulated gold particles on the hydrophobic properties of the obtained coatings was determined.     

IQC robustness analysis for time‐delay systems

Stability robustness of systems with uncertain time delays is considered. A new delay‐dependent state‐space stability criterion is formulated in the form of an easily checked LMI condition. Two applications of the main result are presented, one with only time‐delay uncertainty and one with both delay and parametric uncertainty. Copyright © 2001 John Wiley & Sons, Ltd.     

Integrated Scheme of Natural Gas Usage with Minimum Production of Entropy

Three schemes of the gas turbine cycle have been analyzed from the point of view of the second law of thermodynamics: the conventional gas turbine cycle, where natural gas (methane) is oxidized by air; a closed gas turbine cycle, in which methane is oxidized by oxygen; and a proposed gas turbine cycle, in which the methane is first converted to synthesis gas (a mixture of carbon oxide and hydrogen), then part of the synthesis gas is oxidized by oxygen for electric energy generation while the rest is withdrawn from the power cycle for production of methanol, ether, synthetic fuel, etc. It has been shown that the third integrated scheme of natural gas usage provides minimum entropy increase as well as suppression of toxic nitrogen oxides generation in combustion products. Therefore, it could be considered as a prospective energy‐saving technology.     

Safe Adaptive Switching Control: Stability and Convergence

A formal theoretical explanation of the model-mismatch instability problem associated with certain adaptive control design schemes is proposed, and a solution is provided. To address the model-mismatch problem, a primary task of adaptive control is formulated as finding an asymptotically optimal, stabilizing controller, given the feasibility of adaptive control problem. A class of data-driven cost functions called cost-detectable is introduced that detect evidence of instability without reference to prior plant models or plant assumptions. The problem of designing adaptive systems that are robustly immune to mismatch instability problems is thus placed in a setting of a standard optimization problem. We call the result safe adaptive control because it robustly achieves adaptive stabilization goals whenever feasible, without prior assumptions on the plant model and, hence, without the risk of model-mismatch instability. The result improves the robustness of previous results in hysteresis switching control, both for discrete and for continuously-parameterized candidate controller sets. Examples are provided.     

3D reconstruction for a scanning electron microscope

An algorithm for the reconstruction of the 3D shape of the surface of a micro-object from a stereo pair of images obtained on a raster electron microscope (REM) has been considered. A model of building an image in REM has been presented. The SIFT algorithm was used for determination of the correspondence points. The correspondence points are used to determine the mutual position of the object in a stereo pair by the RANSAC method. A set of points is created in the 3D space, which is later interpolated to reconstruct the 3D surface.     

Near-field optical studies of local photomodification in nanostructured materials

Fractal aggregates of silver nanoparticles are studied experimentally using atomic force microscopy and photon scanning tunnelling microscopy. Large changes in the near-field optical response of fractal aggregates are observed after the irradiation of samples with nanosecond laser pulses. The threshold energy density for photomodification using a 532 nm laser is measured to be 9 mJ cm(-2). It is shown that photomodification-induced changes in the local optical response can be two orders of magnitude larger than changes in far-field absorption.