Ultrahigh molecular weight polyethylene (UHMWPE)/organic montmorillonite (OMMT) nanocomposites were prepared via a self-made vane mixer which could supply a synergy of ultrasound and extensional ...deformation. Structure and working principle of this novel mixer were illustrated in detail. Effects of the OMMT content, mixing time, and ultrasound treat time on composites’ morphology, rheological properties, and thermal properties were reported in terms of transmission electron microscopy (TEM), wide-angle X-ray scattering, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). X-ray diffraction (XRD) and TEM showed that the OMMT lay spacing increased from 2.82 nm to 3.29 nm and OMMT dispersed evenly in the matrix using this novel melt mixing equipment. It certified that the melt mixing procedure synergized by ultrasound and extensional deformation was very effective in the exfoliation of silicate layers and also the filler distribution and dispersion. DSC measurements revealed that the crystallization temperature (T
c) had no visible change with increasing the OMMT content and the melting temperature (T
m) and melting enthalpy crystallinity (X
c) increased with the proper OMMT content. The higher T
m and X
c showed with the proper ultrasound treatment time, however, the T
c had no visible change. TGA showed that the onset temperature at which 20% weight loss of the material increased markedly in the case of UHMWPE/OMMT-1 wt% nanocomposite. The onset temperature slightly decreased with the use of ultrasound. Rheological analyses showed that all the samples exhibited non-Newtonian and shear thinning characteristics. Both the storage modulus and complex viscosity increased with continuous addition of the OMMT layers. It also indicated that the introduction of ultrasound tended to decrease the storage modulus and complex viscosity. Universal tensile test indicated that superior tensile strength occurred in samples containing OMMT layers.
As an important and novel model with multitudinous practical applications, the set-union knapsack problem (SUKP) is a challenging issue in combinatorial optimization. In this paper, we present an ...enhanced moth search algorithm (EMS) for solving SUKP, which introduces an enhanced interaction operator (EIO) by integrating differential mutation into the global harmony search and then Lévy flight is replaced by EIO. Comparative experimental results, which were conducted on three types of 30 popular SUKP benchmark instances, demonstrate that EMS algorithm is superior to or competitive with the other state-of-the-art metaheuristic algorithm. In particular, EMS reaches the best-known solutions for the great majority of test instances and improves the best-known solutions for six instances. Two critical ingredients of EIO is investigated to confirm their impact on the performance of EMS. The results show that both components have an important role in improving the performance of EMS.
As a significant subset of the family of discrete optimization problems, the 0-1 knapsack problem (0-1 KP) has received considerable attention among the relevant researchers. The monarch butterfly ...optimization (MBO) is a recent metaheuristic algorithm inspired by the migration behavior of monarch butterflies. The original MBO is proposed to solve continuous optimization problems. This paper presents a novel monarch butterfly optimization with a global position updating operator (GMBO), which can address 0-1 KP known as an NP-complete problem. The global position updating operator is incorporated to help all the monarch butterflies rapidly move towards the global best position. Moreover, a dichotomy encoding scheme is adopted to represent monarch butterflies for solving 0-1 KP. In addition, a specific two-stage repair operator is used to repair the infeasible solutions and further optimize the feasible solutions. Finally, Orthogonal Design (OD) is employed in order to find the most suitable parameters. Two sets of low-dimensional 0-1 KP instances and three kinds of 15 high-dimensional 0-1 KP instances are used to verify the ability of the proposed GMBO. An extensive comparative study of GMBO with five classical and two state-of-the-art algorithms is carried out. The experimental results clearly indicate that GMBO can achieve better solutions on almost all the 0-1 KP instances and significantly outperforms the rest.
Cuckoo search (CS) is a new robust swarm intelligence method that is based on the brood parasitism of some cuckoo species. In this paper, an improved hybrid encoding cuckoo search algorithm (ICS) ...with greedy strategy is put forward for solving 0-1 knapsack problems. First of all, for solving binary optimization problem with ICS, based on the idea of individual hybrid encoding, the cuckoo search over a continuous space is transformed into the synchronous evolution search over discrete space. Subsequently, the concept of confidence interval (CI) is introduced; hence, the new position updating is designed and genetic mutation with a small probability is introduced. The former enables the population to move towards the global best solution rapidly in every generation, and the latter can effectively prevent the ICS from trapping into the local optimum. Furthermore, the greedy transform method is used to repair the infeasible solution and optimize the feasible solution. Experiments with a large number of KP instances show the effectiveness of the proposed algorithm and its ability to achieve good quality solutions.
The purpose of this paper was to provide an cost-effective methodology for assessing wastewater treatment technology. This methodology may be useful in the planning of treatment facilities in rural ...regions. The existing cost models focus mainly on municipal wastewater treatment plants, which mostly consider the influence of the capacity of plant ordinarily expressed as inhabitants or flow rate. In this paper, we propose a new model of cost function in rural regions that includes both the capacity of plant and the removal rate of pollutants. The water quality indicator chemical oxygen demand and NH3-N are chosen to be factors for a rural wastewater treatment model. The cost model enables us to understand the influence of pollutants’ removal rate and to compare various treatment technologies from an economic point of view. The statistical information comes from a sample of 221 wastewater treatment plants in rural regions located in Changshu, Jiangsu province of China adopting four treatment technologies such as membrane bioreactor technology, sequencing batch reactor, purification tank, biological filter and artificial wetland.
Cuckoo search (CS) is a novel biologically inspired algorithm and has been widely applied to many fields. Although some binary-coded CS variants are developed to solve 0
–
1 knapsack problems, the ...search accuracy and the convergence speed are still needed to further improve. According to the analysis of the shortcomings of the standard CS and the advantage of the global harmony search (GHS), a novel hybrid meta-heuristic optimization approach, called cuckoo search Algorithm with global harmony search (CSGHS), is proposed in this paper to solve 0
–
1 knapsack problems (KP) more effectively. In CSGHS, it is the combination of the exploration of GHS and the exploitation of CS that makes the CSGHS efficient and effective. The experiments conducted demonstrate that the CSGHS generally outperformed the binary cuckoo search, the binary shuffled frog-leaping algorithm and the binary differential evolution in accordance with the search accuracy and convergence speed. Therefore, the proposed hybrid algorithm is effective to solve 0
–
1 knapsack problems.
Laboratory-designed continuous steam explosion (CSE) equipment was used to prepare continuous steam-exploded eucalyptus fibers (CSEEFs). The pretreatment intensity was varied by changing treatment ...time, and effects of CSE on the composition, microstructure, surface composition, thermal properties, and crystallinity of CSEEFs were investigated. Composition analysis showed that CSE had a significant impact on lignin and hemicellulose, but little on cellulose. Scanning electron microscopy indicated that the middle lamella, primary wall, and outer secondary wall were progressively stripped as the CSE time increased. X-ray photoelectron spectroscopy demonstrated that concentrations of extractives and lignin were higher on the surface of eucalyptus wood than CSEEFs’, and the exposed carbohydrate fraction increased with increasing CSE time. Differential scanning calorimetry showed that eucalyptus wood has one glass transition (193.5 °C), whereas two glass transitions at 56.7 and 138.5 °C were observed for CSEEF-5. X-ray diffraction results suggested that crystallinity of samples decreased with increasing CSE time. Thermogravimetric analysis showed the pyrolysis peak temperature of samples first increased and then decreased slightly as CSE time increased. These data will be useful for the optimization and application of CSE technology.
A novel carbon foam with microporous structure (CFMS), with the advantages of a simple fabrication process, low energy consumption, large specific surface area and high conductivity, has been ...prepared by a facile one-step carbonization. In addition, the carbon foam possesses suitable interlayer spacing in short range which is flexible to accommodate the deformation of carbon layer caused by the ion insertion and deinsertion at the charge and discharge state. Furthermore, a low cost carbon-based symmetric potassium dual-ion capacitor (PDIC), which integrates the virtues of potassium ion capacitors and dual-ion batteries, is successfully established with CFMS as both the battery-type cathode and the capacitor-type anode. PDIC displays a superior rate performance, an ultra-long cycle life (90% retention after 10000 cycles), and a high power density of 7800 W kg−1 at an energy density of 39 Wh kg−1. The PDIC also exhibits excellent ultrafast charge and slow discharge properties, with a full charge in just 60 s and a discharge time of more than 3000 s.
Display omitted A symmetric potassium dual-ion capacitor is successfully fabricated with microporous carbon foam as the cathode and anode and exhibits an excellent electrochemical performance.
Polypropylene (PP) and polyethylene (PE) play central roles in our daily life. However, their immiscibility presents a major hurdle in both industry and academia when recycling them into alloys with ...favorable mechanical properties. Moreover, typical compatibilizer-enabled approaches are limited due to increased environmental concerns. Herein, inspired by a traditional Chinese technique, we report a facile, industry-scale methodology that produces a PP/PE binary blend with a highly ordered honeycomb nanostructure without any additives. Due to its nanostructure, the blend exhibits enhanced tensile properties in comparison with the parent components or with a sample prepared using an internal mixer. This approach has potential for applications not only in immiscible polymer blending, but also in non-sorting, compatibilizer-free waste plastics recycling. Through this technique, we expect that an environmentally friendly and sustainable plastic wastes recycling avenue can be found, and great economic benefits can be gained.
The construction of sensitive materials for trace detection is significant for various applications, including structure analysis, environment monitoring, and biological analysis. A critical ...challenge is the construction of materials with a combination of high sensitivity, excellent reliability, and good reusability. Here, we describe a hierarchical Ag–TiO2 composite that can provide three-dimensional hot spots for local electric field enhancement. This substrate can offer stable surface-enhanced Raman scattering (SERS) signal with an absolute intensity that is ∼51 times higher than that of conventional Ag substrate. The SERS signal from the substrate is highly homogenous over a wide region, without any obvious peak fluctuations. Moreover, the composite can be regenerated through an in situ photocatalytic reaction of TiO2. This innovative, recyclable SERS substrate can provide an efficient platform for in situ structure analysis and trace detection.
•Hierarchical Ag–TiO2 composite with three-dimensional hot spots is constructed.•The SERS signal from composite is ∼51 times higher than common Ag substrate.•The SERS signal from composite is highly homogenous and stable.•The composite can be refreshed through in situ photocatalysis reaction of TiO2.
PDF
