88 research outputs found

    An elitist quantum-inspired evolutionary algorithm for the flexible job-shop scheduling problem

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    The flexible job shop scheduling problem (FJSP) is vital to manufacturers especially in today’s constantly changing environment. It is a strongly NP-hard problem and therefore metaheuristics or heuristics are usually pursued to solve it. Most of the existing metaheuristics and heuristics, however, have low efficiency in convergence speed. To overcome this drawback, this paper develops an elitist quantum-inspired evolutionary algorithm. The algorithm aims to minimise the maximum completion time (makespan). It performs a global search with the quantum-inspired evolutionary algorithm and a local search with a method that is inspired by the motion mechanism of the electrons around an atomic nucleus. Three novel algorithms are proposed and their effect on the whole search is discussed. The elitist strategy is adopted to prevent the optimal solution from being destroyed during the evolutionary process. The results show that the proposed algorithm outperforms the best-known algorithms for FJSPs on most of the FJSP benchmarks

    CO2 and CH4 exchanges between land ecosystems and the atmosphere in northern high latitudes over the 21st century

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    Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 33 (2006): L17403, doi:10.1029/2006GL026972.Terrestrial ecosystems of the northern high latitudes (above 50oN) exchange large amounts of CO2 and CH4 with the atmosphere each year. Here we use a process-based model to estimate the budget of CO2 and CH4 of the region for current climate conditions and for future scenarios by considering effects of permafrost dynamics, CO2 fertilization of photosynthesis and fire. We find that currently the region is a net source of carbon to the atmosphere at 276 Tg C yr-1. We project that throughout the 21st century, the region will most likely continue as a net source of carbon and the source will increase by up to 473 Tg C yr-1 by the end of the century compared to the current emissions. However our coupled carbon and climate model simulations show that these emissions will exert relatively small radiative forcing on global climate system compared to large amounts of anthropogenic emissions.This study was supported by a NSF Biocomplexity (ATM-0120468) and ARCSS programs; the NASA Land Cover and Land Use Change and EOS Interdisciplinary Science (NNG04GJ80G) programs; and by funding from MIT Joint Program on the Science and Policy of Global Change, which is supported by a consortium of government, industry and foundation sponsors

    Roadmap for Sustainable Mixed Ionic‐Electronic Conducting Membranes

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    Mixed ionic‐electronic conducting (MIEC) membranes have gained growing interest recently for various promising environmental and energy applications, such as H₂ and O₂ production, CO₂ reduction, O₂ and H₂ separation, CO₂ separation, membrane reactors for production of chemicals, cathode development for solid oxide fuel cells, solar‐driven evaporation and energy‐saving regeneration as well as electrolyzer cells for power‐to‐X technologies. The purpose of this roadmap, written by international specialists in their fields, is to present a snapshot of the state‐of‐the‐art, and provide opinions on the future challenges and opportunities in this complex multidisciplinary research field. As the fundamentals of using MIEC membranes for various applications become increasingly challenging tasks, particularly in view of the growing interdisciplinary nature of this field, a better understanding of the underlying physical and chemical processes is also crucial to enable the career advancement of the next generation of researchers. As an integrated and combined article, it is hoped that this roadmap, covering all these aspects, will be informative to support further progress in academics as well as in the industry‐oriented research toward commercialization of MIEC membranes for different applications

    Making Sense of Institutional Change in China: The Cultural Dimension of Economic Growth and Modernization

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    Optimal inspection policy for three-state systems monitored by variable sample size control charts

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    This paper presents the expected long-run cost per unit time for a system monitored by an adaptive control chart with variable sample sizes: if the control chart signals that the system is out of control, the sampling which follows will be conducted with a larger sample size. The system is supposed to have three states: in-control, out-of-control, and failed. Two levels of repair are applied to maintain the system. A minor repair will be conducted if an assignable cause is confirmed by an inspection, and a major repair will be performed if the system fails. Both the minor and major repairs are assumed to be perfect. We derive the expected long-run cost per unit time, which can be used to obtain the optimal inspection policy. Numerical examples are conducted to validate the derived cost

    Studies on adsorption of phenol and 4-nitrophenol on MgAl-mixed oxide derived from MgA1-layered double hydroxide

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    In this research, the removal of two phenols (4-nitrophenol and phenol) from aqueous solution was investigated using MgAl-mixed oxide. This oxide was prepared by calcining crystalline MgAl-CO3-layered double hydroxide (LDH) at 500 degrees C for 4 h. we found that it takes 10-12 h for adsorption of 4-nitrophenol to reach the equilibrium at room temperature while the equilibrium time is 20-25 h for phenol adsorption. The kinetic process of 4-nitrophenol adsorption seemingly follows the first-order reaction but phenol is adsorbed in a pseudo-second-order model. We also noted that the maximum adsorption amount of 4-nitrophenol by fitted three-parameter Langmuir-Freundlich isotherm is 367.8 mg/g, much higher than that of phenol (46.9 mg/g). The differences in the adsorption kinetics and dynamics have been related to the adsorption mechanism and adsorbate-adsorbent interactions. The reconstruction of MgAl-mixed oxide in aqueous solution incorporates 4-nitrophenolate into the interlayer. However, it is difficult to intercalate phenolate due to its weaker affinity for LDH in comparison with OH-. In addition, adsorption of MgAl-mixed oxide for 4-nitrophenol and phenol is slightly affected by the initial pH, but considerably facilitated by increasing the adsorption temperature. (c) 2009 Elsevier B.V. All rights reserved

    Visible-light-driven sonophotocatalysis and peroxymonosulfate activation over 3D urchin-like MoS2C nanoparticles for accelerating levofloxacin elimination: Optimization and kinetic study

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    © 2019 Elsevier B.V. Solar response catalysts designed, sustainable wastewater-purification technology developed, possesses huge advantage in resolving the global issue of scarcity of drinkable water availably. In this work, a smart 3D core-shell urchin-like MoS2/carbon photocatalyst was developed with special hollow interior and the internal carbon layer embedding, which could largely enhance the electrical conductivity of MoS2, accelerate the electron transfer efficiency, and provide more active sites The effect of the pollutant concentration, the initial pH, co-existing anions, peroxymonosulfate (PMS) dose and ultrasonic intensity are carried out to explore the performance of sonophotocatalytic coupling system for levofloxacin degradation under visible light irradiation. Following the optimized condition, the MoS2/C catalyst presented excellent degradation rate (0.0702 min−1) in PMS activated sonophotocatalytic system (synergy index reaching to 2.6). The active radical trapping, degradation intermediates and possible catalytic mechanism were investigated and proposed, respectively. Based on these results, the unique development, fabrication, core/shell strategy, and high-efficiency coupling approach would motivate new models of wastewater treatment technologies
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