Adaptive Optimal Discrete-Time Output-Feedback Using an Internal Model Principle and Adaptive Dynamic Programming

In order to address the output feedback issue for linear discrete-time systems, this work suggests a brand-new adaptive dynamic programming (ADP) technique based on the internal model principle (IMP). The proposed method, termed as IMP-ADP, does not require complete state feedback-merely the measurement of input and output data. More specifically, based on the IMP, the output control problem can first be converted into a stabilization problem. We then design an observer to reproduce the full state of the system by measuring the inputs and outputs. Moreover, this technique includes both a policy iteration algorithm and a value iteration algorithm to determine the optimal feedback gain without using a dynamic system model. It is important that with this concept one does not need to solve the regulator equation. Finally, this control method was tested on an inverter system of grid-connected LCLs to demonstrate that the proposed method provides the desired performance in terms of both tracking and disturbance rejection.     

The dyes possessing diazine residue as effective photoinitiators of free radicals polymerization

Summary The series of the dyes possessing diazine residue have been investigated as visible-light absorbing photoinitiators of free radical polymerization. The rates of photoinitiation depend on the structure of the dye. Mechanism of the photoinitiation involves the electron transfer process between the dye and the electron donor (co-initiator). The dyes possessing diazine residue in the presence of a suitable electron donor are very effective photoinitiators. This can be attributed to the high quantum yield of their triplet state formation and high rate constant of electron transfer reaction between the dye and electron donor.     

The effect of co-initiator structure on photoinitiating efficiency of photoredox couples composed of quinoline[2,3-b]-1H-imidazo[1,2-a]pyridinium bromide and phenoxyacetic acid or N,N-dimethylaniline derivatives.

Summary  Two groups of electron donors (phenoxyacetic acid derivatives, PAADs, and the family of N,N-dimethylaniline derivatives DMADs) in combination with quinoline[2,3-b]-1H-imidazo[1,2-a]pyridinium bromide (QIPB) were applied as photoinitiator for free radical polymerization induced with UV emission of an argon-ion laser (351 and 361 nm). Analysis of the data obtained for the initial time of photoinitiated polymerization indicates that both, the rate of electron transfer process between QIPB and tested co-initiators as well as the structure of obtained free radical can affect the overall photoinitiation ability of tested photoredox pairs.     

Statically admissible finite element solution of the thin plate bending problem with a posteriori error estimation

Two triangular elements of class C⁰ developed on the basis of the principle of complementary work are applied in the static analysis of a thin plate. Some techniques to widen the versatility of the equilibrium approach for the finite element method are presented. Plates of various shapes subjected to diverse types of loading are considered. The results are compared with outcomes obtained by use of the displacement-based finite element method. By use of these two dual types of solutions, the error of the approximate solution is calculated. The lower and upper bounds for the strain energy are found.     

HfO2:Eu nanoparticles excited by X-rays and UV-visible radiation used in biological imaging

Europium doped hafnium dioxide nanoparticles were crystallized using biologically friendly microwave hydrothermal method and employed in observation of small rodents tissues.Main solvent in synthesis is water,in consequence nanoparticles are found surrounded by thin hydroxide layer.Size of the nanoparticles is controlled by temperature of calcination.1200℃heating causes drop of luminescence intensity,explained as damage of high symmetry surface emission centers in the nanocrystals.On the other hand,growth of crystallites increases intensity of X-ray and electron beam excited luminescence.This makes them promising activator in photodynamic therapy.     

Rough sets

We investigate in this paper approximate operations on sets, approximate equality of sets, and approximate inclusion of sets. The presented approach may be considered as an alternative to fuzzy sets theory and tolerance theory. Some applications are outlined.     

Design and application of a new knowledge engineering tool for solving real-world problems

The results of a broader cognitive research on an intelligent knowledge engineering program environment are described. This intelligent programming tool features an open architecture, modularity and an idea to use multistrategy learning, multistrategy knowledge representation and integration of various schemes of knowledge processing in a single inferential process. Some selected applications of the developed tool, carefully examined at various levels, are briefly dealt with.     

Evaluation of potential applications of recycled moulding and core sands to production of ceramic building materials

This study summarises the properties of ceramic materials containing used moulding sand, from processed and recycled mould and core mixes. The sand preparation procedure involves crushing and separation of metallic parts. Thus obtained substance acts as a substitute for natural quartz sand, commonly used as a leaning agent in ceramic plastic bodies to be formed into ceramic-based construction materials. The study summarises the basic functional parameters, structure and microstructure of ceramic materials made from plastic bodies containing variable qualitative proportions of used sand. The issues addressed in the paper include the potential threats associated with manufacturing and disposal of these types of materials. Potential hazards include atmospheric emissions of hazardous gaseous substances in the form of polycyclic aromatic hydrocarbons (PAHs) as derivatives of organic binders used for manufacturing of moulding and core sand mixes. These substances are formed in the process of combustion of ceramic products or can be produced when heavy metals are released from the ceramic matrix. This process can occur throughout the entire service life of ceramic products under the specific conditions. Applicability of used sand in this disposal scheme is well proved by good parameters of thus obtained ceramic materials and positive test results evidencing the absence of atmospheric emissions of hazardous substances and low-level leaching of heavy metals.     

Fracture toughness,strength and creep of transparent ceramics at high temperature

Fracture toughness, four-point bending strength of transparent spinel, Y₂O₃ and YAG ceramics in function of temperature (from room temperature up to 1500° C) were measured. Creep resistance at 1500–1550° C was studied too. Grain size distribution was determined on polished and etched surfaces of samples. Fracture surfaces after tests were examined by scanning electron microscopy. The obtained results showed that: in the case of spinel ceramics fracture toughness and strength decreased from 20 to 800° C, increased from 800 to 1200° C and decreased at higher temperature; in the case of Y₂O₃ ceramics they increased from 400 to 800° C, and next kept constant up to 1500° C; in the case of YAG ceramics they kept constant from 20 to 1200° C and then decreased. The creep strain rate was measured for spinel and YAG but not for Y₂O₃ ceramics which appeared creep resistant. The hypotheses concerning toughening and creep mechanisms were proposed.     

Superelasticity of NiTi Ring-Shaped Springs Induced by Aging for Cranioplasty Applications

This paper concerns the application of titanium-nickel rings in modeling the cranium. After being fixed to the osseous margins, the ring’s expansion at the same time broadens and shortens the cranium vault. The rings formed from a straight superelastic wire, flattened to an ellipse, do not show the presence of a typical force plateau but rather a pseudoelastic loop during loading-unloading in the relationship between the force and the deflection. Based on the idea that superelasticity in more complex shape-springs may be induced by the precipitation hardening process, the further studies were carried out on alloys with higher nickel contents (51.06 at.% Ni). The rings that had been formed were welded and aged at an optimal temperature and time. The improved superelastic behavior during compression and unloading the rings was obtained by introducing small deformation by drawing the quenched wires before forming the rings and aging. Very positive clinical reshaping by long-term distraction with the superelastic ring-shaped springs was achieved in young children under one year and a less spectacular effect was observed in the group of older children.