The decomposition-based evolutionary multiobjective optimization (EMO) algorithm has become an increasingly popular choice for a posteriori multiobjective optimization. However, recent studies have ...shown that their performance strongly depends on the Pareto front (PF) shapes. This can be attributed to the decomposition method, of which the reference points and subproblem formulation settings are not well adaptable to various problem characteristics. In this paper, we develop a learning-to-decompose (LTD) paradigm that adaptively sets the decomposition method by learning the characteristics of the estimated PF. Specifically, it consists of two interdependent parts, i.e., a learning module and an optimization module. Given the current nondominated solutions from the optimization module, the learning module periodically learns an analytical model of the estimated PF. Thereafter, useful information is extracted from the learned model to set the decomposition method for the optimization module: 1) reference points compliant with the PF shape and 2) subproblem formulations whose contours and search directions are appropriate for the current status. Accordingly, the optimization module, which can be any decomposition-based EMO algorithm in principle, decomposes the multiobjective optimization problem into a number of subproblems and optimizes them simultaneously. To validate our proposed LTD paradigm, we integrate it with two decomposition-based EMO algorithms, and compare them with four state-of-the-art algorithms on a series of benchmark problems with various PF shapes.
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Membrane separation processes are often perplexed by severe and ubiquitous membrane fouling. Zwitterionic materials, keeping electric neutrality with equivalent positive and negative ...charged groups, are well known for their superior antifouling properties and have been broadly utilized to construct antifouling surfaces for medical devices, biosensors and marine coatings applications. In recent years, zwitterionic materials have been more and more frequently utilized for constructing antifouling membrane surfaces. In this review, the antifouling mechanisms of zwitterionic materials as well as their biomimetic prototypes in cell membranes will be discussed, followed by the survey of common approaches to incorporate zwitterionic materials onto membrane surfaces including surface grafting, surface segregation, biomimetic adhesion, surface coating and so on. The potential applications of these antifouling membranes are also embedded. Finally, we will present a brief perspective on the future development of zwitterionic materials modified antifouling membranes.
Membrane fouling is a severe problem hampering the application of membrane separation technology. The properties of membrane surfaces play a critical role in membrane fouling and antifouling behavior/performance. Antifouling membrane surface construction has evolved as a hot research issue for the development of membrane processes. Zwitterionic modification of membrane surfaces has been recognized as an effective strategy to resist membrane fouling. This review summarizes the antifouling mechanisms of zwitterionic materials inspired by cell membranes as well as the popular approaches to incorporate them onto membrane surfaces. It can help form a comprehensive knowledge about the principles and methods of modifying membrane surfaces with zwitterionic materials. Finally, we propose the possible future research directions of zwitterionic materials modified antifouling membranes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The demand for thin-film composite nanofiltration membranes bearing unprecedented water permeance and desirable salt rejection is ever increasing in desalination. Conventional interfacial ...polymerization usually generates a thick (∼100 nm) skin layer on hydrophobic substrate having low-porosity, leading to limited water permeance. Herein, we engineered a highly porous and superhydrophilic composite substrate to modulate the interfacial polymerization and generate an ultrathin polyamide skin layer, even below 10 nm. The composite substrate was constructed by depositing covalent organic framework nanosheets (CONs) on a microfiltration membrane
via
vacuum-assistant assembly. Owing to the highly porous structure and superhydrophilic nature of CONs, the composite substrate favored a high storage capacity and uniform distribution of the amine monomers. We manipulated the monomer storage capacity of the substrate by varying the loading content of CONs and demonstrated that higher amino monomer concentration could accelerate the self-sealing and self-termination of the interfacial polymerization, thus generating a thinner skin layer from ∼70 nm to sub-10 nm. Moreover, the highly porous structure of CONs imparted little additional water transport resistance. The sub-10 nm film composite membrane exhibited a superior water permeance of 535.5 L m
−2
h
−1
MPa
−1
with a high rejection of 94.3% for Na
2
SO
4
, which was about 2-8 times higher than that of state-of-the-art nanofiltration membranes with comparable rejection.
Covalent organic framework modulated interfacial polymerization enables the formation of ultrathin polyamide membrane for high-performance desalination.
The balance between convergence and diversity is the cornerstone of evolutionary multiobjective optimization (EMO). The recently proposed stable matching-based selection provides a new perspective to ...handle this balance under the framework of decomposition multiobjective optimization. In particular, the one-one stable matching between subproblems and solutions, which achieves an equilibrium between their mutual preferences, is claimed to strike a balance between convergence and diversity. However, the original stable marriage model has a high risk of matching a solution with an unfavorable subproblem, which finally leads to an imbalanced selection result. In this paper, we introduce the concept of incomplete preference lists into the stable matching model to remedy the loss of population diversity. In particular, each solution is only allowed to maintain a partial preference list consisting of its favorite subproblems. We implement two versions of stable matching-based selection mechanisms with incomplete preference lists: one achieves a two-level one-one matching and the other obtains a many-one matching. Furthermore, an adaptive mechanism is developed to automatically set the length of the incomplete preference list for each solution according to its local competitiveness. The effectiveness and competitiveness of our proposed methods are validated and compared with several state-of-the-art EMO algorithms on 62 benchmark problems.
Wheat straw returning is widely practiced in agriculture; therefore, it is critical to determine the physicochemical and bacterial indicators in soil for the organic carbon storage, accumulative C ...mineralization, total nitrogen improvement, and nitrogen mineralization in various soil types after wheat straw returning. This study evaluated the influenced indicators of wheat straw addition on soil organic carbon and nitrogen transformation in diverse soil types. For this purpose, an incubation experiment was conducted to analyze the carbon and nitrogen transformation in soil from eight Chinese provinces treated with the same dry weight of wheat straw. The results indicated that the primary physicochemical and bacterial indicators that predict the carbon and nitrogen transformations in the acidic and alkaline soils were different. Of all the natural physicochemical properties of soil, cation exchange capacity and clay content were significantly correlated with organic carbon, mineralized carbon, total nitrogen, and mineralized nitrogen in the alkaline soil. In the acidic soil, the initial C/N ratio of soil was the most significant indicator of carbon and nitrogen transformation. From the perspective of the carbon- and nitrogen-relating bacterial communities, Proteobacteria were largely responsible for the accumulative C mineralization in both types of soil. Furthermore, Proteobacteria strongly regulated the organic carbon storage in the acidic soil after wheat straw addition, whereas Gemmatimonadetes was the main predicted indicator in the alkaline soil. Additionally, total nitrogen and mineralized nitrogen levels were largely explained by Bifidobacterium and Luteimonas in the alkaline soil and by Nitrospira and Bdellovibrio in the acidic soil. Soil physicochemical and biological properties significantly influence soil carbon and nitrogen transformation, which should be considered crucial indicators to guide the rational regulation of straw return in several areas.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A new method of ultraviolet light (UV) activated persulfate (PS) oxidation was investigated to regenerate granular activated carbon (GAC) in drinking water applications. The improvements in iodine ...and methylene blue numbers measured in the GAC after ultraviolet- (UV) activated persulfate suggested that the GAC preloaded with natural organic matter (NOM) was chemically regenerated. An experimental matrix for UV-activated persulfate regeneration included a range of persulfate doses and different UV wavelengths. Over 87% of the initial iodine number for GAC was restored under the optimum conditions, perfulfate dosage 60 g/L and UV exposure 1.75 × 104 mJ/cm2. The persulfate dosages had little effect on the recovery of the methylene blue number, which was approximately 65%. Persulfate activation at 185 nm was superior to activation at 254 nm. UV activation of persulfate in the presence of GAC produced acid, lowering the solution pH. Higher persulfate concentrations and UV exposure resulted in greater GAC regeneration. Typical organic and inorganic byproducts (e.g., benzene compounds and sulfate ions) were measured as a component of treated water quality safety. This study provides a proof-of-concept that can be used to optimize pilot-scale and full-scale UV-activated persulfate for regeneration of NOM-saturated GAC.
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•The technical feasibility of the regeneration for NOM-saturated GAC by UV-activated persulfate was investigated.•GAC regeneration results were obtained under higher persulfate concentrations and 185 nm UV exposure dose.•Both iodine and methylene blue numbers were measured as an indicator of GAC adsorption capacity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Nitrogen (N) deposition plays a significant role in soil cadmium (Cd) phytoremediation, and poplar has been considered for the remediation of contaminated soil because of its enormous biomass and ...strong Cd resistance. To reveal the underlying physiological and root phenotypic mechanisms of N deposition affecting Cd phytoextraction in poplar, we assessed root phenotypic characteristics, Cd absorption and translocation, chlorophyll fluorescence performance, and antioxidant enzyme activities of a clone of Populus deltoides × P. nigra through combined greenhouse Cd and N experiments. Our results showed that Cd significantly changed the root phenotype by reducing root length, tip number, and diameter. Cd also caused the peroxidation of lipids, damaged the photosystem II (PSII) reaction centre, and reduced photosynthetic capacity, resulting in a decrease in biomass accumulation in poplar. The N60 (60 kg N·ha−1·yr−1) and N90 (90 kg N·ha−1·yr−1) treatments promoted the net photosynthetic rate of poplar by increasing the activity of antioxidant enzymes and proline content and repairing the PSII reaction centre, thus increasing the biomass accumulation of poplar exposed to Cd stress. Simultaneously, the N60 and N90 treatments might have increased Cd uptake from the soil by upregulating total root length, root tips, and fine root length. Cd mainly accumulated in roots and stems but not in leaves. The N30 (30 kg N·ha−1·yr−1) treatment had no obvious effects on these parameters compared with the single Cd treatment. Consequently, our study suggested that adequate N can improve biomass and Cd accumulation to enhance the phytoremediation capacity of poplar for Cd, which might be related to the improvement of leaf physiological defence and the change in root phenotypic characteristics.
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•A combined Cd and N experiment was conducted to study the effects of N deposition on Cd phytoremediation of poplar.•N increased Cd uptake and accumulation in the roots and stems of poplar.•N improved the Cd tolerance of poplar.•N upregulated root phenotypic characteristics of poplar exposed to Cd.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Land supply in China is planned by governments, and the supply ratios of various types of land are in relatively rigid administrative control. This paper constructs a DSGE model to study the ...relationship between land supply marketization in China and economic fluctuations. Moreover, this paper evaluates the social welfare gains from land marketization. We document that the government’s land planning constraint impacts consumption and social welfare through the land price and final output, causing resource misallocation losses in aggregate investment and output. Quantitatively, the optimal upper limit of industrial land supply is about 40% to achieve the maximum social welfare. This paper stresses the necessity of revitalizing China’s land market, and simultaneously speeding up the marketization of collectively operated construction land.
Compared with the ground focusing mechanism, the working environment of space focusing mechanism is more harsh and complicated. Hence the accurate prediction of its reliability is indispensable. ...However, it is unrealistic to obtain sample parameters of reliability analysis through repeated entity tests, due to the limitation of project cost and timetable, which lead to many existing model cannot be applied directly. We focus on a screw guide type space focusing mechanism, and propose a new time varying reliability probabilistic model that can characterize the reliability of discontinuous motion mechanisms with discrete multi-load. Its primary uncertainties and failure modes are evaluated quantitatively by failure mode effects analysis. The total damage of intermittent operation is treated as accumulative effect caused by each focusing work. And main parameters of the model are obtained by analytical calculation of mechanism wear reliability model. Finally, an integrated theoretical method are constructed and verified in this article, and the time varying reliability of proposed focusing mechanism are also discussed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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