Fuzzy α-discounting method for multi-criteria decision-making

The α-Discounting Method was developed to be an alternative to and extension of the Analytical Hierarchy Process (AHP) to solve multi-criteria decision-making (MCDM) problems with non-commensurable and conflicting criteria. In contrast to the AHP, this method works not only for pairwise comparisons but also for n-wise comparisons if relative importance of criteria can be expressed in a system of linear homogenous equations. This method also has a comparative advantage as it can transform those MCDM problems, classified as inconsistent by the AHP, into a consistent form. This study briefly compares the two methods and then develops the Fuzzy α-Discounting Method for Multi-Criteria Decision Making (Fα-DM MCDM). Two illustrative fuzzy MCDM problems from the literature have been solved to show how the Fα-DM MCDM works.     

Recursive Gauss–Seidel algorithm for direct self‐tuning control

A recursive algorithm based on the use of Gauss–Seidel iterations is introduced to adjust the parameters of a self‐tuning controller for minimum phase and a class of nonminimum phase discrete‐time systems. The proposed algorithm is called the Recursive Gauss–Seidel (RGS) algorithm and is used to update the controller parameters directly. The use of the RGS algorithm with a generalized minimum variance control law is also given for nonminimum phase systems, and a forgetting factor is used to track the time‐varying parameters. Furthermore, the overall stability of the closed‐loop system is proven by using the Lyapunov stability theory. Using computer simulations, the performance of the RGS algorithm is examined and compared with the widely used recursive least squares algorithm.Copyright © 2011 John Wiley & Sons, Ltd.     

A de novo formulation of metformin using chitosan-based nanomicelles for potential diabetes therapy

A de novo formulation of metformin (MET) was developed through the physical loading of drug into a chitosan-grafted-[poly(acryl amide)-block-poly(acrylic acid)] [CS-g-(PAAm-b-PAA)] terpolymer. For this purpose, CS was functionazed with phthalic anhydride followed by 4-cyano, 4-[(phenylcarbothioyl)sulfanyl]pentanoic acid to produc a macro-RAFT agent (CS-CTA). Afterward, acryl amide and acrylic acid monomers were graft and block copolymerized onto the synthesized CS-CTA through a reversible addition–fragmentation chain transfer (RAFT) polymerization technique to afford CS-g-PAAm copolymer and CS-g-(PAAm-b-PAA) terpolymer, respectively. The fabricated CS-g-(PAAm-b-PAA) terpolymer was loaded with MET as an anti-diabetic drug, and its drug release behavior was evaluated in the body simulated environment. As results, it was concluded that the fabricated CS-g-(PAAm-b-PAA) nanosystem has high potential as de novo drug delivery system (DDS) for diabetes therapy, mainly due to controlled drug release profile in comparison with conventional formulations of MET. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48037.     

Hydrogen cycle with sodium borohydride

In this paper, we review production of NaBH₄ as hydrogen storage material. Linking this with other processes, we create a system to recycle hydrogen. Difficulties and advantages of NaBH₄ synthesis by natural available boron source colemanite and borax minerals were discussed. We show that basic chemicals suffice for NaBH₄ production in a procedure designed to work below 275 °C. This procedure may be used to compensate for the loss of materials during the recycle. In this procedure, hydrogen including substances have been used to remove oxygen and bond remaining hydrogen to the by-product NaBO₂ of dehydrogenation reaction. The wet and dry applications of producing NaBH₄ have been also discussed. Moreover, a shorter procedure can be proposed to directly obtain NaBH₄ from borax mineral. Among these processes, dehydrogenation is critical but it requires plenty of water. Hence, new types of catalyst are important to reduce the amount of water required during dehydrogenation.     

Numerical simulation of fluid flow and heat transfer in a trapezoidal microchannel with COMSOL multiphysics: A case study

In this study, fluid flow and heat transfer in a trapezoidal microchannel are numerically investigated. For this purpose, a reference study with experimental and numerical solutions is adopted from the literature and solved with COMSOL multiphysics. Good agreement with the results of the reference work is obtained. In addition, effects of stabilization methods and element discretization options that are offered by the program on the results are investigated and discussed with examples. In addition, two different versions of the same program are compared on the effect of stabilization methods on results. Last, some comments on the level of relative tolerance are provided.     

Preparation of N‐doped graphene‐based electrode via electrochemical method and its application in vanadium redox flow battery

An N‐doped graphene electrode has been prepared by cyclic voltammetric method in 5.0 M of HNO₃ solution on a graphite‐based electrode at room temperature. The modification of the electrode surface with different types of N‐containing groups, such as nitro groups, pyrrolic N, and pyridinic N, has been controlled by changing the scanned potential ranges. The formation of an N‐doped graphene electrode has been confirmed by scanning electron microscopic, atomic force microscopic, X‐ray photoelectron, and Raman spectroscopic methods. The prepared N‐doped graphene‐modified electrodes have been used in positive electrolyte of a vanadium‐based redox flow battery. As positive electrodes, the electrochemically modified electrodes prepared in 5.0 M of HNO₃ solution ?1.0 to (+1.9) and ?0.7 to (+1.9) V had more than 140 and 120 mA/cm² anodic and cathodic peak currents, respectively, in vanadium redox battery. This fast, low‐cost, and environmentally friendly method can be used in many application areas, such as optical devices, (bio)sensors, energy storage materials, and electronic devices.     

Pool boiling of perfluorocarbon mixtures on silicon surfaces

The need for higher pool boiling critical heat flux (CHF) in electronic cooling applications has turned attention to the use of binary mixtures of dielectric liquids. The available literature demonstrates that the addition of a liquid with higher saturation temperature, higher molecular weight, higher viscosity and higher surface tension can lead to significant enhancement of CHF, beyond what can be achieved through changes in pressure, liquid subcooling, and the product of surface effusivity and heater thickness. The current study focuses on extending the available data on mixture CHF enhancement, as well as pool boiling, on polished silicon surfaces to FC-72/FC-40 mixture ratios of 10%, 15%, and 20% of FC-40 by weight, a pressure range of between 1 and 3 atm, and fluid temperature from 22 to 45 °C, leading to high subcooling conditions. It is found that peak heat flux can be increased to as high as 56.8 W/cm² compared to 25.2 W/cm² for pure FC-72 at 3 atm and 22 °C. It is believed that the increase in the mixture latent heat of evaporation and surface tension, accompanying the depletion of the lower boiling point fluid in the wall region plays the major role in enhancing the critical heat flux for binary mixtures.     

Capacity-driven acceptance of customer orders for a multi-stage batch manufacturing system: models and algorithms

An automotive parts manufacturer produces a wide variety of parts in a job shop environment. Many of the manufacturing operations have substantial setups. When a client phones in an order, the manufacturer must decide quickly whether or not it has the capacity required to accept the order. We develop a simplified formulation of the order acceptance problem. We formulate the discrete-time version as an integer program. The problem is NP-hard, but in 51 out of 51 test problems the LP relaxation is tight. For larger problems we test several heuristics. Three of the heuristics look promising: simulated annealing, a genetic algorithm, and a linear-programming-based heuristic.