Some studies on uncertainty management in dynamical systems using cybernetic approaches and fuzzy techniques with applications

Uncertain information processing by fuzzy if–then rules has received much attention. Here we have taken a different path to model a system, about which we do not have precise information, namely modelling the system by fuzzy-valued functions without resorting to fuzzy if–then rules. As a result, the phase (state) space of the system becomes a fuzzy set and the underlying fuzzy mapping becomes a fuzzy attainability set mapping. Uncertain or fuzzy dynamical systems have been defined in terms of fuzzy attainability set mappings. Fuzzy differentiable dynamical systems have been discussed with a particular emphasis on fuzzy differential inclusion (FDI) relations. An evolutionary algorithm for solving one-dimensional FDIs has been developed. A model of the creation of a tropical cyclone in the form of a vortex, created by winds coming from different directions and colliding under certain conditions, has been proposed in terms of FDIs. A model has been considered for the highly uncertain system of evolution of a tumour in a human body and an FDI relation model of the whole system has been proposed and simulated. The model of an evolution of turbulence, as a random occurrence of vortices in a three-dimensional dynamic fluid, has been proposed and simulated, where each vortex is modelled by a fuzzy-valued function, where uncertain parameter and variable values are fuzzy numbers. All the systems represented by FDI relations have been simulated with the help of the evolutionary algorithm mentioned above.     

Architectural View of Flexible Aliphatic –OH Group Coordinated Hemi-Directed Pb(II)-Salen Coordination Polymer: Synthesis,Crystal Structure,Spectroscopic Insights,Supramolecular Topographies,and DFT Perspective

Journal of Inorganic and Organometallic Polymers and Materials - We serendipitously designed one novel 1D hetero-binuclear Zn(II)-Pb(II) coordination polymer, namely...     

Synthesis and characterization of perfectly alternating polycarbonate‐polydimethylsiloxane multiblock copolymers possessing controlled block lengths

An array of perfectly alternating polycarbonate‐polydimethylsiloxane (PC‐PDMS) multiblock copolymers possessing systematic variations in block molecular weights were successfully produced by coupling preformed PC and PDMS telechelic oligomers using hydrosilylation. Based on gel permeation chromatography results, the multiblock copolymers were essentially void of the oligomeric precursors. Despite the relatively large difference in solubility parameter between PC and PDMS, the multiblock copolymers exhibited significant partial miscibility between the two phases. As expected, the degree of partial miscibility was dependent on the molecular weight of the blocks with the extent of partial miscibility increasing with decreasing block molecular weights. Morphological characterization using small angle X‐ray scattering showed that, at a given PC block molecular weight, the uniformity of the two phase morphology increased with increasing PDMS block molecular weight, which is consistent with a decrease in the extent of phase mixing with increasing PDMS block molecular weight. POLYM. ENG. SCI., 54:1648–1663, 2014. © 2013 Society of Plastics Engineers     

Effect of co‐solvents on the photovoltaic performance of an inverted organic solar cell

We investigated the effect of varying polymer crystallinity, morphology, and optical property, produced by adding four different co‐solvents in to the poly(3‐hexylthiophene) (P3HT): [6,6]‐phenyl C₆₁‐butyric acid methyl ester (PCBM) active layer blend solution, on the functioning of an inverted polymeric solar device. Photovoltaic devices primed with cyclohexanone co‐solvent showed the best performance with power conversion efficiency (PCE) reaching a value of 3.01 ± 0.04%. Improvement in efficiency is related to an increase in photocurrent which is due to a combined result of ordered P3HT crystallite growth, as well as of the precise size and phase separation of domains. POLYM. ENG. SCI., 55:1382–1388, 2015. © 2015 Society of Plastics Engineers     

Sodium effects on mechanical performance and consideration in high temperature structural design for advanced reactors

Sodium environmental effects are key limiting factors in the high temperature structural design of advanced sodium-cooled reactors. A guideline is needed to incorporate environmental effects in the ASME design rules to improve the performance reliability over long operating times. This paper summarizes the influence of sodium exposure on mechanical performance of selected austenitic stainless and ferritic/martensitic steels. Focus is on Type 316SS and mod.9Cr-1Mo. The sodium effects were evaluated by comparing the mechanical properties data in air and sodium. Carburization and decarburization were found to be the key factors that determine the tensile and creep properties of the steels. A beneficial effect of sodium exposure on fatigue life was observed under fully reversed cyclic loading in both austenitic stainless steels and ferritic/martensitic steels. However, when hold time was applied during cyclic loading, the fatigue life was significantly reduced. Based on the mechanical performance of the steels in sodium, consideration of sodium effects in high temperature structural design of advanced fast reactors is discussed.     

Pairing Fluctuations, the BCS–BEC Crossover and Strong Disorder in Superconductors

The mean field theory due to Bardeen, Cooper, and Schrieffer (BCS) provides the conceptual foundation of our understanding of superconductivity, but many examples over the last few decades have forced condensed matter physicists to extend the BCS framework. In particular, the extension to strong coupling, the BCS to Bose–Einstein condensation (BEC) crossover, requires the treatment of amplitude and phase fluctuations above the mean field state. Similarly, the presence of disorder can lead to strong inhomogeneity in the pairing amplitude, enhance phase fluctuations, and suppress the transition temperature. Finally, magnetic scattering quickly leads to a gapless superconducting state and then the loss of order. All of these involve physics beyond the BCS scenario. We employ a real space method that reduces to inhomogeneous mean field theory in the ground state, but fully retains the amplitude and phase fluctuations of the pairing field at finite temperature. This paper reviews some of our work in the weak to strong coupling (BCS–BEC) crossover, the disorder driven superconductor-insulator transition, and the role of magnetic impurities.     

Weld Metal Microstructure Prediction in Submerged Arc Weld Metal of C‐Mn Steel

The prediction model has been developed for steel weld metal microstructural constituents as a function of flux ingredients such as CaO, MgO, CaF₂ and Al₂O₃ in submerged arc welding carried out at fixed welding parameters. The results of quantitative measurements of micro‐structural constituents on eighteen weld metal samples were utilised for developing the prediction equations of microstructural constituents applying statistical design of experiment for mixtures. Among the flux ingredients, CaO appears to be most important as an individual as well as interaction with other ingredients viz. CaF₂ and Al₂O₃ in influencing the amount of microstructural constituents in weld metal. The prediction equations have been checked for adequacy by performing tests on welding using randomly designed flux and found satisfactory. The iso‐response curves were developed for selected microstructural constituents to show their output levels at different percentage of flux ingredients.