Tuning PI controllers for stable processes with specifications on gain and phase margins

In industrial practice, controller designs are performed based on an approximate model of the actual process. It is essential to design a control system which will exhibit a robust performance because the physical systems can vary with operating conditions and time. Gain and phase margins are well known parameters for evaluating the robustness of a control system. This paper presents a tuning algorithm to design and tune PI controllers for stable processes with a small dead time while meeting specified gain and phase margins. Simulation examples are given to demonstrate that the proposed design method can result, in a closed-loop system, in better performances than existing design methods which are also based on user-specified gain and phase margins.     

Synthesis,Thermal and Morphological Properties of Polyurethanes Containing Azomethine Linkage

This paper presents synthesis, photophysical, electrochemical, thermal and morphological properties of Schiff bases containing various side-group substitutions and polyurethanes (PUs) containing azomethine linkage. Morphological properties of PUs containing azomethine bonding were investigated by scanning electron microscopy (SEM). SEM images showed that PU containing azomethine consist of semi-crystalline particles. Thermal transitions in PUs containing azomethine units were studied using DSC. The obtained DSC curves showed that PUs containing azomethine are semi-crystalline materials due to they contain both crystallization and melting peaks. Electrochemical properties also investigated by using cyclic voltammetry (CV). According to the cyclic voltommagrams and CV data, PUs containing azomethine have below 2.0 eV electrochemical band gap.     

The use of basalt powder as a natural heterogeneous catalyst in the Fenton and Photo-Fenton oxidation of cationic dyes

The use of naturally present heterogeneous catalysts has recently been an essential issue in the Fenton and photo-Fenton processes. In this study, the uses of basalt as a catalyst for the Fenton and photo-Fenton reactions for methylene Blue (MB) and Basic Red 18 (BR18) degradations were investigated. Basalt was selected because of the presence of the iron (III) oxide in the structure. Basalt was characterized by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) analysis to obtain the chemical composition and the crystalline phase. The surface charge and the surface area were obtained by zeta potential and Brunauer Emmett-Teller (BET) analysis. Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscope (SEM) were utilized to explore the functional group and the surface morphology. Fenton and photo-Fenton processes were applied to explore the best degradation method. Adsorption was also tested and the adsorption process had minimum removal efficiency (12% for MB and 17% for BR18). The removal efficiencies for MB and BR18 by the Fenton process were 87% and 28%, respectively. The photo-Fenton process had maximum removal efficiency with 100% for MB and 70% for BR18. The optimum conditions were 70 mg/L dye concentration, 5 mM H₂O₂, 1.0 g/L basalt loading and pH 2. Basalt has shown reuse capability as a catalyst for three consecutive cycles.     

Innovative hydrogen release from sodium borohydride hydrolysis using biocatalyst-like Fe2O3 nanoparticles impregnated on Bacillus simplex bacteria

For the first time in this innovative study, microorganisms such as Bacillus simplex bacteria, mostly used in biological activity studies, are used as a bio-supporter agent of iron to release hydrogen from sodium borohydride hydrolysis at 25.0 ± 0.1 °C. The goal is to investigate thoroughly sodium borohydride hydrolysis catalyzed by Fe₂O₃ nanoparticles impregnated on microorganism such as Bacillus simplex (BS) bacteria (Fe₂O₃@BS NPs) known with strong antibacterial properties, which makes innovative them a candidate for hydrolysis reaction. This study was focused on the preparation, identification, and catalytic use of biocatalyst-like Fe₂O₃@BS NPs for hydrogen release from the sodium borohydride hydrolysis at 25.0 ± 0.1 °C. The characterization results made after and before hydrolysis reaction using by SEM/SEM-EDX, FT-IR, XRD, UV–vis, XPS, DLS, ELS Zeta potential, ESR, and TEM techniques reveal the formation of highly active, stable, durable, and long-lived biocatalysts-like Fe₂O₃@BS NPs.     

Synthesis and characterizations of poly(ether)/poly(phenol)s including azomethine coupled benzothiazole side chains: the effect of reaction conditions on the structure,optical, electrochemical,electrical and thermal properties

A new Schiff base, 4-((6-ethoxybenzothiazole-2-ylimino)methyl)benzene-1,2-diol (3,4-HBAEBT) was synthesized by the condensation reaction of 3,4-dihydroxybenzaldehyde (3,4-HBA) and 2-amino-6-ethoxybenzothiazole. The Schiff base, then, was converted to its polymer derivatives by oxidative polycondensation reaction in both organic (P-1) and aqueous alkaline medium (P-2). Spectral observations indicated different structural properties for each polymerization condition. Organic and aqueous alkaline medium produced poly(ether) and poly(phenol) structures, respectively. The obtained polymers were separately studied with respect to optical, electrochemical, electrical and thermal properties. With exception of thermal degradation behaviors, the other investigated properties as well as morphological characteristics of both polymers were considerably different. In the fluorescence measurements a solvatochromic effect was recorded and the emission colors of the polymers could be changed as turquoise-green by solvent change.