Abstract
In order to achieve the informational and intelligent management of the municipal resources, this article uses platforms like IntelJ IDEA development tools and MySQL database, with the use ...of spring framework and B/S architecture, develops a municipal resource optimization configuration management system. In this system, MyBaits finishes the management of the data. The grey models and exponential smoothing algorithms have done the prediction part of the demand for the municipal resources corresponding to the flow of people and vehicles. The municipal department can perceive the demand for resources through this forecasting function and then allocate the corresponding municipal resources in advance. The development of this system can simplify the work process of municipal departments when there is a demand to manage the resources. It is of great significance to improve the working efficiency and the resources utilization rate of the municipal departments.
As micro-CT devices have become widely available, the detailed 3D microstructures of cementitious materials can be more conveniently investigated. However, owing to the resolution required to ...appropriately represent the cement-paste microstructures, the domain size of the micro-CT sample is limited. By synergistically combining the virtual and real experiments, correlations between the microstructural characteristics and properties of cement paste with various w/c ratios (0.3, 0.4, 0.5, and 0.6) are investigated at different length scales. The porosity from the micro-CT images are correlated with the macro-scale properties obtained from real experiments. At the micro-scale, the homogenized solid phase properties are characterized from the linear attenuation coefficient (LAC) value distribution characteristic of the micro-CT images and are correlated with the modeling parameters of the phase field fracture. According to the results of virtual experiments conducted using the phase field fracture model and the characterization methods, the mechanical properties (stiffness/strength) at the micro- and macro-scale exhibited apparent relationships.
•The properties of cement paste are correlated with the microstructural characteristics obtained from micro-CT.•The cement paste microstructure is idealized as two-phase (pore/solid) material.•The micro-scale cement paste mechanical properties and porosity from the micro-CT images are correlated.•The solid phase properties are correlated with the mean linear attenuation coefficient (LAC) from the micro-CT images.
This study investigated a strategy to simulate splitting tests to evaluate the tensile strength of cement paste within a multiscale framework, and validated the approach with in-situ micro-CT ...measurements. Phase-field fracture model was used to simulate the splitting test using virtual microstructures reconstructed from the macroscale micro-CT measurements. Among the modeling parameters, the range of the diffusive crack width, which is an internal parameter for phase-field fracture model, was further investigated. The cracks propagated through the weaker solid phase, and the predicted strengths and standard deviations were comparable to those obtained from the experiments. It was found that the diffusive crack width should be smaller than the characteristic length of the weaker phase to predict the crack pattern accurately. These findings confirm the effectiveness of the proposed multiscale modeling approach in predicting the tensile strength of cement paste.
•A simulation approach to predict tensile strength of cement paste is validated with in-situ micro-CT.•The range of diffusive crack width, a modeling parameter, is proposed based on microstructure.•Crack patterns in cement paste microstructures from simulation and experiments are comparable.•The predicted tensile strength distributions are similar to those from the experiments.
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•Wear-resistant CNR fillers were embedded into PVDF matrix.•The fraction of the non-polar α-phase in PVDF increased.•The friction and adhesion properties of the composites were ...improved.•The composite with 10 wt% CNR showed excellent tribological performances.
High-tribological performance composites were prepared by incorporating wear-resistant carbon nanorod (CNR) fillers into a poly(vinylidene fluoride) (PVDF) matrix. CNRs with a diameter of 300 nm were synthesized via electrospinning a polyacrylonitrile solution followed by pyrolysis. The incorporation of the CNR filler increased the fraction of the non-polar α-phase in the PVDF matrix, which improved the friction and interfacial adhesion properties of the composites. The composites showed excellent frictional performance and wear resistance owing to self-lubricating property and scaffold effect of the CNR filler. The lowest friction coefficient was obtained at the CNR loading of 10 wt%. Compared to neat PVDF, the friction coefficient and wear rate of the PVDF/CNR composite with 10 wt% CNR loading decreased significantly from 0.43 to 0.03 and 8.43 × 10−5 to 3.70 × 10−5 mm3/N m, respectively. These values represent excellent tribological performances for polymer-based composites.
The Manta ray foraging optimization (MRFO) is a novel swarm-based metaheuristic optimizer. It is mainly modeled by simulating three foraging behaviors of the Manta rays, which has a good performance. ...However, several drawbacks of MRFO have been noticed by analyzing its mathematical model. Random selection of reference points in the early iterations weakens the exploitation capability of MRFO. Chain foraging tends to lead the algorithm into local optimum. In addition, the algorithm suffers from the deficiency of decreasing population diversity in the late iteration. To address these shortcomings, a modified MRFO using three strategies, called m-MRFO, is proposed in this paper. An elite search pool (ESP) is established in this paper to enhance exploitation capability. By using adaptive control parameter strategies (ACP), we expand the range of MRFO's exploration in the early iterations and enhance the accuracy of exploitation in the later iterations, balancing exploiting and exploring capabilities. Furthermore, we use a distribution estimation strategy (DES) to adjust the evolutionary direction using the dominant population information to promote convergence. The m-MRFO performance was verified by selecting 23 classical test functions and CEC2017 test suite. The significance of the results was also verified by Friedman test, Wilcoxon test and Iman-Davenport test. Moreover, we have confirmed the potential of m-MRFO to solve real-world problems by solving three engineering design problems. The simulation results show that the improvement strategy proposed in this paper can effectively improve the performance of MRFO. m-MRFO is highly competitive.
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•A synthetic amendment was developed to improve composting and resource recycling.•Biodegradation and maturity were analyzed, and metabolic pathways were annotated.•Dominant bacteria ...and fungi were similar but with different richness in three groups.•Study showed pathways of predicted carbohydrate metabolism during composting.•Synthetic amendment achieved mature compost and can be reused to conserve resources.
This research investigated a synthetic amendment to improve composting and resource recycling of pig manure and biogas residue. We further examined whether adding a synthetic amendment impacts the microbial ecosystem in the composted materials. Three mixing ratios were used to investigate composting performance: no synthetic amendment (T0), 5% synthetic amendment (T1), and 10% synthetic amendment (T2) (T1 and T2 were measured as a wet weight ratio). There were no significant differences in the fundamental characteristics between composting products in T0 and T1. The moisture content of composting material in T0, T1, and T2 significantly decreased from a baseline of approximately 65% to 35.5%, 37.3%, and 55.9%, respectively. Meanwhile, the germination index significantly increased to 111.6%, 155.6%, and 62.3%, respectively. When an optimal proportion of synthetic amendment was added, T1 showed high degree of humification, lignocellulase activities, and effective biodegradation. Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes were the dominant bacteria, while Ascomycota and Basidiomycota were the dominant fungi in all treatment groups. Amino sugar and nucleotide sugar metabolism, glycolysis, starch, and sucrose metabolism were among the primary pathways in predicted functions. The synthetic amendment can generate a mature composting product and can be reused or recycled to conserve resources.
The pore distribution of a cement paste strongly affects its mechanical behavior such as its stiffness and strength. Porosity is an influential parameter that can be used to identify the complex pore ...microstructures of cement paste, but it has limitations as a scalar parameter. In this study, the lineal-path function, a low-order probability function, is investigated as a supplement or an alternative parameter for describing the microstructural characteristics of cement paste microstructures. In particular, the area of the lineal-path function is used as a measure of the pore microstructural characteristics, which can be linked with its properties.
A relatively new method for simulating crack propagation, the crack phase field model, is used to evaluate the stiffness and tensile strength of cement paste microstructures and the evaluated properties are linked to the proposed characterization parameters. The evaluation is performed on virtual specimens obtained from micro-level computerized tomography (μ-CT) images of real cement paste specimens. The validity of the microstructure-property relations obtained from the proposed characterization parameters and the crack phase field model are confirmed through the statistical analysis of dozens of specimens.
It is concluded that the correlation between the area of the lineal-path function and the mechanical properties is very strong. The parameter could potentially be used as a supplementary or an alternative parameter to describe the pore microstructures of cement paste.
► The experimental results of thermal conductivity values for concrete. ► The effectiveness of lightweight aggregate and glass bead as replacement materials for coarse aggregates were assessed. ► The ...thermal conductivity of insulated concrete was reduced with increasing fraction of lightweight aggregates and glass beads. ► The linear and plane heat source methods are proposed and implemented to obtain conductivity values for specimens.
Passive energy-saving houses and buildings made of thermally insulated materials become popular in recent construction practices to address the demanding energy needs and to reduce the consumption of hydrocarbon energy resources. Thermally insulated concretes represent alternative construction materials to improve the thermal efficiency in a wide range of residential and commercial buildings. This study presents the experimental results of thermal conductivity values of lightweight concrete materials at ambient temperature conditions. Various lightweight aggregates and glass bubbles are selected as surrogates and replacement materials for coarse aggregates in order to reduce the thermal conduction in concretes. The linear and plane heat source methods are implemented to quantitatively obtain conductivity values for tested specimens. Results highlight that the thermal conductivity of concretes can be effectively reduced with increasing fraction of lightweight aggregates critically depending on the type of lightweight aggregates, thereby playing an important role in the thermal insulation. The addition of micro-meter sized hollow glass bubbles further decreases the thermal conductivity of specimens while its impact is less pronounced than the lightweight aggregates. The measurement of strength corroborates the soundness of mechanical applicability of tested concretes specimens as well.
The unmanned aerial vehicle (UAV) path planning problem is a type of complex multi-constraint optimization problem that requires a reasonable mathematical model and an efficient path planning ...algorithm. In this paper, the fitness function including fuel consumption cost, altitude cost, and threat cost is established. There are also four set constraints including maximum flight distance, minimum flight altitude, maximum turn angle, and maximum climb angle. The constrained optimization problem is transformed into an unconstrained optimization problem by using the penalty function introduced. To solve the model, a multiple population hybrid equilibrium optimizer (MHEO) is proposed. Firstly, the population is divided into three subpopulations based on fitness and different strategies are executed separately. Secondly, a Gaussian distribution estimation strategy is introduced to enhance the performance of MHEO by using the dominant information of the populations to guide the population evolution. The equilibrium pool is adjusted to enhance population diversity. Furthermore, the Lévy flight strategy and the inferior solution shift strategy are used to help the algorithm get rid of stagnation. The CEC2017 test suite was used to evaluate the performance of MHEO, and the results show that MHEO has a faster convergence speed and better convergence accuracy compared to the comparison algorithms. The path planning simulation experiments show that MHEO can steadily and efficiently plan flight paths that satisfy the constraints, proving the superiority of the MHEO algorithm while verifying the feasibility of the path planning model.
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