Probability density function of bubble size based reagent dosage predictive control for copper roughing flotation

As an effective measurement indicator of bubble stability, bubble size structure is believed to be closely related to flotation performance in copper roughing flotation. Moreover, reagent dosage has a very important influence on bubble size structure. In this paper, a novel reagent dosage predictive control method based on probability density function (PDF) of bubble size is proposed to implement the indices of roughing circuit. Firstly, the froth images captured in the copper roughing are segmented by using a two-pass watershed algorithm. In order to characterize bubble size structure with non-Gaussian feature, an entropy based B-spline estimator is hence investigated to depict the PDF of the bubble size. Since the weights of B-spline are interrelated and related to the reagent dosage, a multi-output least square support vector machine (MLS-SVM) is applied to depict a dynamic relationship between the weights and the reagent dosage. Finally, an entropy based optimization algorithm is proposed to determine reagent dosage in order to implement tracking control for the PDF of the output bubble size. Experimental results can show the effectiveness of the proposed method

A hybrid multiobjective differential evolution algorithm and its application to the optimization of grinding and classification

The grinding-classification is the prerequisite process for full recovery of the nonrenewable minerals with both production quality and quantity objectives concerned. Its natural formulation is a constrained multiobjective optimization problem of complex expression since the process is composed of one grinding machine and two classification machines. In this paper, a hybrid differential evolution (DE) algorithm with multi-population is proposed. Some infeasible solutions with better performance are allowed to be saved, and they participate randomly in the evolution. In order to exploit the meaningful infeasible solutions, a functionally partitioned multi-population mechanism is designed to find an optimal solution from all possible directions. Meanwhile, a simplex method for local search is inserted into the evolution process to enhance the searching strategy in the optimization process. Simulation results from the test of some benchmark problems indicate that the proposed algorithm tends to converge quickly and effectively to the Pareto frontier with better distribution. Finally, the proposed algorithm is applied to solve a multiobjective optimization model of a grinding and classification process. Based on the technique for order performance by similarity to ideal solution (TOPSIS), the satisfactory solution is obtained by using a decision-making method for multiple attributes

Correction: An intrinsically stretchable humidity sensor based on anti-drying, self-healing and transparent organohydrogels

Correction for ‘An intrinsically stretchable humidity sensor based on anti-drying, self-healing and transparent organohydrogels’ by Jin Wu et al., Mater. Horiz., 2019, 6, 595–603, DOI: 10.1039/C8MH01160E

Computational fluid dynamics investigation of thermal-hydraulic characteristics in a simplified pebbled bed modular reactor core using different arrangements of fuel elements

High-temperature gas-cooled reactor is a kind of advanced nuclear reactor in which the core is packed with spherical fuel elements. In high-temperature gas-cooled reactors, the operating temperature is higher than that in ordinary light water reactors. In an attempt to analyze the flow pattern and heat transfer situation to provide reference for the safe operation of the pebble bed reactors, a segment of simplified high-temperature gas-cooled reactor core is simulated with computational fluid dynamics method. Four kinds of arrangement, including simple cubic, body-centered cubic, face-centered cubic, and a combination structure of body-centered cubic and face-centered cubic, are studied, respectively. Based on the simulation results, higher heat transfer capability and lower pebble temperature are obtained in the case with the most compact arrangement. The drag coefficient (Cd) for four arrangements with different inlet Reynolds number (Re) is obtained and relationship between Re and Cd is analyzed. In addition, a simulation with a broken fuel element in the body-centered cubic fluid domain has been performed. The results show that the presence of broken fuel may result in uneven flow, which will change the heat transfer condition. So it is better to avoid broken fuel element in a high-temperature gas-cooled reactor

Superdeformed Band in ^{36}Ar Described by Projected Shell Model

The projected shell model implements shell model configuration mixing in the projected deformed basis. Our analysis on the recently observed superdeformed band in $^{36}$Ar suggests that the neutron and proton 2-quasiparticle and the 4-quasiparticle bands cross the superdeformed ground band at the same angular momentum. This constitutes a picture of band disturbance in which the first and the second band-crossing, commonly seen at separate rotation frequencies in heavy nuclei, occur simultaneously. We also attempt to understand the assumptions of two previous theoretical calculations which interpreted this band. Electromagnetic properties of the band are predicted.Comment: 4 pages and 2 figures, accepted by Phys. Rev. C as a Rapid Communicatio

HiTIC-Monthly: a monthly high spatial resolution (1 km) human thermal index collection over China during 2003–2020

Human-perceived thermal comfort (known as human-perceived temperature) measures the combined effects of multiple meteorological factors (e.g., temperature, humidity, and wind speed) and can be aggravated under the influences of global warming and local human activities. With the most rapid urbanization and the largest population, China is being severely threatened by aggravating human thermal stress. However, the variations of thermal stress in China at a fine scale have not been fully understood. This gap is mainly due to the lack of a high-resolution gridded dataset of human thermal indices. Here, we generated the first high spatial resolution (1 km) dataset of monthly human thermal index collection (HiTIC-Monthly) over China during 2003–2020. In this collection, 12 commonly used thermal indices were generated by the Light Gradient Boosting Machine (LightGBM) learning algorithm from multi-source data, including land surface temperature, topography, land cover, population density, and impervious surface fraction. Their accuracies were comprehensively assessed based on the observations at 2419 weather stations across the mainland of China. The results show that our dataset has desirable accuracies, with the mean R2, root mean square error, and mean absolute error of 0.996, 0.693 ∘C, and 0.512 ∘C, respectively, by averaging the 12 indices. Moreover, the data exhibit high agreements with the observations across spatial and temporal dimensions, demonstrating the broad applicability of our dataset. A comparison with two existing datasets also suggests that our high-resolution dataset can describe a more explicit spatial distribution of the thermal information, showing great potentials in fine-scale (e.g., intra-urban) studies. Further investigation reveals that nearly all thermal indices exhibit increasing trends in most parts of China during 2003–2020. The increase is especially significant in North China, Southwest China, the Tibetan Plateau, and parts of Northwest China, during spring and summer. The HiTIC-Monthly dataset is publicly available from Zenodo at https://doi.org/10.5281/zenodo.6895533 (Zhang et al., 2022a).</p

Self-Assembled 3D Flower-Like Hierarchical β-Ni(OH)2Hollow Architectures and their In Situ Thermal Conversion to NiO

Three-dimensional (3D) flower-like hierarchicalβ-Ni(OH)2hollow architectures were synthesized by a facile hydrothermal route. The as-obtained products were well characterized by XRD, SEM, TEM (HRTEM), SAED, and DSC-TGA. It was shown that the 3D flower-like hierarchicalβ-Ni(OH)2hollow architectures with a diameter of several micrometers are assembled from nanosheets with a thickness of 10–20 nm and a width of 0.5–2.5 μm. A rational mechanism of formation was proposed on the basis of a range of contrasting experiments. 3D flower-like hierarchical NiO hollow architectures with porous structure were obtained after thermal decomposition at appropriate temperatures. UV–Vis spectra reveal that the band gap of the as-synthesized NiO samples was about 3.57 eV, exhibiting obviously red shift compared with the bulk counterpart