Optimal control of biotechnological processes described by fuzzy sets

Fuzzy set theory is applied to extend the optimal control problem for complex objects such as biotechnological processes. It allows inclusion of all possible and admissible process states in the problem formulation. A new approach for model representation with convenient fuzzy sets taking into account expert experience is proposed. Bellman-Zadeh's approach is applied to transform a fuzzy optimal control problem ot a deterministic one which is solved numerically. Optimal control of a real-life fermentation process is determined and a better solution is reached due to more realistic and flexible problem formulation.     

On the complexity of graph self-assembly in accretive systems

We study the complexity of the Accretive Graph Assembly Problem (). An instance of consists of an edge-weighted graph G, a seed vertex in G, and a temperature τ. The goal is to determine if the graph G can be assembled by a sequence of vertex additions starting from the seed vertex. The edge weights model the forces of attraction and repulsion, and determine which vertices can be added to a partially assembled graph at the given temperature. A vertex can be added when the total weight to its already built neighbors in the graph is at least τ. The assembly process is sequential meaning that only one vertex can be added at a time. Our first result is that is NP-complete even on planar graphs with maximum degree 3 when edges have only two different types of weights. This resolves the complexity of in the sense that the problem is poly-time solvable when either the maximum degree is at most 2 or the number of distinct edge weights is one, and is NP-complete otherwise. Our second result is a dichotomy theorem that completely characterizes the complexity of on graphs with maximum degree 3 and two distinct weights: w _p and w _n . We give a simple system of linear constraints on w _p , w _n , and τ that determines whether the problem is NP-complete or is poly-time solvable. In the process of establishing this dichotomy, we give a poly-time algorithm to solve a non-trivial class of Finally, we consider the optimization version of where the goal is to assemble a largest-possible induced subgraph of the given input graph. We show that even on graphs that can be assembled and have maximum degree 3, it is NP-hard to assemble a (1/n ^1-ε)-fraction of the input graph for any here n denotes the number of vertices in G.     

Empirical Fuzzy Sets

In this paper, we introduce a new form of describing fuzzy sets (FSs) and a new form of fuzzy rule‐based (FRB) systems, namely, empirical fuzzy sets (εFSs) and empirical fuzzy rule‐based (εFRB) systems. Traditionally, the membership functions (MFs), which are the key mathematical representation of FSs, are designed subjectively or extracted from the data by clustering projections or defined subjectively. εFSs, on the contrary, are described by the empirically derived membership functions (εMFs). The new proposal made in this paper is based on the recently introduced Empirical Data Analytics (EDA) computational framework and is closely linked with the density of the data. This allows to keep and improve the link between the objective data and the subjective labels, linguistic terms, and classes definition. Furthermore, εFSs can deal with heterogeneous data combining categorical with continuous and/or discrete data in a natural way. εFRB systems can be extracted from data including data streams and can have dynamically evolving structure. However, they can also be used as a tool to represent expert knowledge. The main difference from the traditional FSs and FRB systems is that the expert does not need to define the MF per variable; instead, possibly multimodal, densities will be extracted automatically from the data and used as εMFs in a vector form for all numerical variables. This is done in a seamless way whereby the human involvement is only required to label the classes and linguistic terms. Moreover, even this intervention is optional. Thus, the proposed new approach to define and design the FSs and FRB systems puts the human “in the driving seat.” Instead of asking experts to define features and MFs correspondingly, to parameterize them, to define algorithm parameters, to choose types of MFs, or to label each individual item, it only requires (optionally) to select prototypes from data and (again, optionally) to label them. Numerical examples as well as a naïve empirical fuzzy (εF) classifier are presented with an illustrative purpose. Due to the very fundamental nature of the proposal, it can have a very wide area of applications resulting in a series of new algorithms such as εF classifiers, εF predictors, εF controllers, and so on. This is left for the future research.     

Klisurits kaolin deposit

Glass and Ceramics -     

Sol-Gel Synthesis and Structure of Nanocomposites Based on Tetraethoxysilane and Boron Compounds

Glass Physics and Chemistry - The properties of sol-gel synthesis of borosilicate sols, wet gels and xerogels, as well as thin nanosized films were studied. Physicochemical processes and phenomena...     

Thresholds of optical limiting in solutions of nanoscale compounds of zinc phthalocyanine with galactopyranosyl radicals

The optical limiting (OL) of nanosecond laser pulses in solutions of newly synthesized dyes in dimethyl sulfoxide (DMSO) has been investigated. These dyes are compounds of zinc phthalocyanine (ZnPc) with D-galactopyranosyl radicals (Gal) located in the peripheral (p-GalZnPc) and nonperipheral (n-GalZnPc) positions with respect to the ZnPc macrocycle. Experiments have been performed using laser radiation with a wavelength of 532 nm, at which the optical absorbance of solutions of ZnPc, p-GalZnPc and n-GalZnPc dyes is four orders of magnitude lower than the absorbance in the peaks at wavelengths of 671, 680, and 701 nm, respectively. It is established that solutions of p-GalZnPc and n-GalZnPc in DMSO have a much lower OL threshold in comparison with ZnPc solution; the nonlinearity of p-GalZnPc solutions exceeds that of n-GalZnPc solutions. OL thresholds for the dyes under study in a wide concentration range are determined.     

Injection seeding in a dual-cavity gain-switched Ti:Sapphire laser

Abstract

An experimental investigation of a pulsed tunable injection-seeding system pumped by a Nd:YAG laser is presented. The slave laser (SL) of the system is a gain-switched Ti:Sapphire laser with a dual-channel competitive cavity which consists of a main ring channel and an auxiliary linear one with different lengths. The use of this configuration results in full and reliable suppression of both the perturbing reverse radiation from the SL to the master laser (ML) and the broadband spectral background of the SL's ring channel. This is achieved irrespective of the ratio between the energies of the SL and ML, fluctuations of laser parameters, and spectral detuning. We take advantage of the gain-switched regime of the Ti:Sapphire laser to avoid simultaneous competition between the SL's channels; this allows us to obtain spectrally pure, unidirectional output radiation with high seeding and overall efficiency. The principle of operation of the ring-linear-cavity Ti:Sapphire slave laser provides a natural optical isolation between the SL and ML; this makes such lasers suitable for use as regenerative amplifiers when seeded by single-frequency diode lasers as well as in chirped-pulse-amplification systems to amplify ultrashort laser pulses without the necessity of optical isolators.     

Pressure drop in pulsed extraction columns with internals of discs and doughnuts

A study on the pressure drop in pulsed extraction columns with internals of immobile discs and rings, usually called Discs and Doughnuts Columns (DDC) is carried out. The local pressure at a desired level of the column is obtained by resolving of turbulent flow model based on Reynolds equations coupled with k–? model of turbulence. Consequently, the pressure drop for a column stage or for a unit of column length is determined. The results are used for development of correlations for determination of pressure drop as a function of plate free area, interplate distance and pulsation parameters – amplitude and frequency. Good correspondence to experimental data is observed. The developed quantitative relations are useful for non-experimental numerical optimization of stage geometry in view of lesser energy consumption.     

Polycrystalline silicon thin films obtained by metal-induced crystallization

The formation of high-quality polycrystalline silicon (poly-Si) on different substrates has important applications in the development of thin-film transistors, solar cells, image sensors, etc. In this study, we present the results of an investigation of poly-Si films on glass, formed by aluminum-induced crystallization. The process is based on the isothermal annealing for 3 h at 500 °C of co-sputtered Al+Si or sputtered a-Si films on glass, with and without thermally evaporated Al. The poly-Si films were investigated by Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy.     

Polymer-stabilized liquid crystal indicator used in thermometry

Research on the biological effects and on critical-temperature alarm indicators for fire safety often requires the use of non-metallic and reliable temperature sensors. For such applications, we investigated the temperature dependence of the spectral response of a pure cholesteric liquid-crystal temperature indicator and of a polymer/liquid crystal mixture. We observed a modulation of the intensity of transmitted monochromatic light, in accordance with the temperature changes. We emphasize that the modulation occurs over a wide temperature range outside the active temperature of the thermochromic liquid-crystal indicator. Such behavior suggests the possibility of using these liquid crystals in a wider temperature range, under appropriate conditions. The spectral response of the liquid crystal in its active temperature range shows that a thermochromic liquid crystal indicator may be practically used as a precision thermometer.