Efficient three-component Gewald reactions under Et3N/H2O conditions

In a medium consisting of triethylamine and water, α-methylene ketones undergo room temperature Gewald reactions with elemental sulfur and ethyl cyanoacetate (or malononitrile) to yield 2-aminothiophene derivatives efficiently within short time periods. Because of the high polarity of the medium, products precipitate in the reaction mixtures spontaneously. This makes isolation of the products easy by simple filtration and avoids cumbersome chromatographic separations. Mechanistic studies suggest that the reactions proceed via a Knoevenagel condensation pathway.     

Overlapping control systems with optimal information exchange

This paper deals with the stabilizability of interconnected systems via linear time-invariant (LTI) decentralized controllers. Given a controllable and observable system with some distinct decentralized fixed modes (DFMs), it is desired to find a suitable control structure (in terms of information flow) for it. Since a decentralized controller consists of a number of non-interacting local controllers, the objective here is to establish certain interactions between the local controllers in order to eliminate the undesirable DFMs. This objective is achieved by translating the knowledge of the system into some bipartite graphs. Then, the notions of minimal sets and maximal subgraphs are introduced, which lead to a simple combinatorial algorithm for solving the underlying problem. The efficacy of the results obtained is demonstrated by an illustrative example.     

Bi-objective resource constrained project scheduling problem with makespan and net present value criteria: two meta-heuristic algorithms

Traditionally, the model of a resource-constrained project-scheduling problem (RCPSP) contains a single objective function of either minimizing project makespan or maximizing project net present value (NPV). In order to be more realistic, in this paper, two multi-objective meta-heuristic algorithms of multi-population and two-phase sub-population genetic algorithms are proposed to find Pareto front solutions that minimize the project makespan and maximize the project NPV of a RCPSP, simultaneously. Based on standard test problems constructed by the RanGen project generator, a comprehensive computational experiment is performed, where response surface methodology is employed to tune the parameters of the algorithms. The metaheuristics are computationally compared, the results are analyzed, and conclusions are given at the end.     

Pd doped WO3 films prepared by sol–gel process for hydrogen sensing

The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al₂O₃ substrates by spin coating method. XRD and XPS techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500 °C. We observed that Pd can modify the growth kinetic of tungsten trioxide nanoparticles by reducing the crystallite size and as a result can improve hydrogen sensitivity. Resistance-sensing measurements indicated sensitivity of about 2.5 × 10⁴ at room temperature in hydrogen concentration of 0.1% in air. Considering all sensing parameters, an optimum working temperature of 100 °C was obtained.     

Multi-Objective Hydraulic Optimization of Diversion Dam’s Cut-Off

The seepage flow beneath a hydraulic structure is formed by the hydraulic head difference between the upstream and downstream sides. Cut-off walls are often applied, as an expedience, to reduce the seepage flow through the foundation of diversion dams and to enhance the efficiency of these dams. In this research, perhaps for the first time, a novel methodology is propounded to assess the optimum characteristics of cut-off walls in diversion dams in order to ameliorate hydraulic interactions between the diversion dam foundation and the cut-off walls behavior, also their construction cost is minimized. The results are used to train and validate the Multi-Layer Perceptron (MLP) simulation model. Then MLP, as a meta-model for simulation of the hydraulic behavior of cut-off walls, is coupled with a robust multi-objective optimization algorithm, Non-dominated Sorting Genetic Algorithm-ΙΙ (NSGA-ΙΙ), to create a trade-off between the intended goals. Finally, Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE) decision making model and Nash-Harsanyi bargaining model are utilized to find the compromise design optimal solution on the trade-off curve. Results demonstrate that the best agreed-upon design optimal solution using PROMETHEE and Nash-Harsanyi bargaining models can be considered as (10, 3.84, 32) meters and (2.47, 10, 29.22) meters for optimum depth of the upstream and downstream cut-off walls and the optimum distance between them, respectively.     

An efficient solid phase extraction of Pb2+ using tannic acid-coated cerium oxide nanoparticles followed by electrothermal atomic absorption spectrometry

Cerium oxide-Tannic acid (CeO₂-TA) nanocomposite were used for preconcentration of Pb²⁺ followed by electrothermal atomic absorption spectrometry. Cerium oxide nanoparticles were synthesized by microwave method and modified by tannic acid to produce CeO₂-TA nanocomposite. In order to optimize the experimental conditions, Response surface methodology based on central composite design was used. The obtained results show that the calibration curve was linear in the range of 0.025–1.5 µg L^?1 Pb²⁺. Also, the accuracy of the method was validated by the analysis of certified referenced material. Finally, the proposed method was applied for determination of Pb²⁺ in different real samples.     

On rough set and fuzzy sublattice

Let L be a lattice with the least element 0 and the greatest element 1 and let θ be a full congruence relation on L. In this paper, the notion of θ-upper and θ-lower approximations of a fuzzy subset of L is introduced and some important properties will be studied.     

Transactive energy management for optimal scheduling of interconnected microgrids with hydrogen energy storage

In recent years, renewable energy sources (RESs) have attracted substantial attention due to carbon-free and cost-effective advantages that have made them one of the main sources of energy generation in the modern structure of the power grid. This paper proposes the stochastic day-ahead scheduling model for optimal energy management of renewable-based microgrids. In this paper, each microgrid is equipped with 100% RESs including the PV system and wind turbine for full pollutant-free energy generation while the hydrogen energy storage (HES) system is used for alleviating the intermittences of the RESs aiming to dynamically balance the energy during a day. To model the fluctuations such as day-ahead market price in the microgrids, the autoregressive integrated moving average and fast forward selection methods are exerted for scenario production and reduction, respectively. Transactive energy as a sustainable and reliable technique is considered for controlling and coordinating energy sharing among the microgrids and the energy network for dynamic energy balancing in the deregulated environment. For energy management in the demand-side, the price and load response schemes are presented, aiming to revise the consumers' patterns in energy consumption in line with balancing energy and minimizing the microgrids’ energy cost. The effectiveness of the suggested model is validated using the modified IEEE 24-bus case study. The realistic modeling of the system based on the proposed model has led to an 8.51% increment in energy cost.