Research progress in the removal of fluoride ions from mine water by adsorption method

Fluoride ions are widely distributed in surface rivers and groundwater bodies in China, especially in the mining areas along the Yellow River in the western Yellow River basin that there is a widespread problem of excessive fluoride in the mine water, which poses a potential threat to the local ecological environment and human health. The status quo of fluoride pollution in China is mostly at a low concentration pollution level, which leads to it difficult to remove efficiently through conventional water treatment technologies. The adsorption method is considered to be an effective way to remove low concentration fluoride ions because of its high adsorption efficiency and convenient operation. The research status of fluoride removal by commonly used adsorption materials such as carbon based, minerals, metals and metal organic frameworks (MOFs) was reviewed and summarized before summarizing the influence of different factors on the fluoride removal efficiency and adsorption mechanism of these adsorption materials. Then the application effect and operation cost of adsorption method in mine water treatment were emphatically analyzed, and the development direction of adsorption method in the treatment of low concentration (<10 mg/L) and high water content fluorine-containing mine water was prospected. In general, there are still some deficiencies in the study of fluoride removal by adsorption. In terms of adsorption mechanism, it should be further investigated from three aspects which includes the characteristics of adsorption materials, the occurrence form of fluoride ions and the interaction mechanism between adsorption materials and fluoride ions. For the engineering application of adsorption method, the demand of engineering application should be regarded as the guidance. Based on the above discussion, the research and development direction of removing fluoride ions from mine water by adsorption method is proposed, which is to focus on the development of low cost and high efficiency environment-friendly modified adsorbents based on natural/waste (ore) and carbon-based, aluminum-based or other new polymer adsorption materials under the principle of clarifying local policies and water quality and quantity. In addition, it is necessary not to improve the selective adsorption performance of the modified adsorbent for fluoride ions, but also to ensure the stability, economy and safety of the adsorbent in the whole life cycle of preparation, processing, production and recycling, thereby improving its competitiveness of the adsorption method in the actual application of fluoride containing wastewater and enhancing the application potential of the adsorption method

Image-based camera localization: an overview

Abstract Virtual reality, augmented reality, robotics, and autonomous driving, have recently attracted much attention from both academic and industrial communities, in which image-based camera localization is a key task. However, there has not been a complete review on image-based camera localization. It is urgent to map this topic to enable individuals enter the field quickly. In this paper, an overview of image-based camera localization is presented. A new and complete classification of image-based camera localization approaches is provided and the related techniques are introduced. Trends for future development are also discussed. This will be useful not only to researchers, but also to engineers and other individuals interested in this field

Numerical Simulation and Optimization of Enhanced Oil Recovery by the In Situ Generated CO2 Huff-n-Puff Process with Compound Surfactant

This paper presents the numerical investigation and optimization of the operating parameters of the in situ generated CO2 Huff-n-Puff method with compound surfactant on the performance of enhanced oil recovery. First, we conducted experiments of in situ generated CO2 and surfactant flooding. Next, we constructed a single-well radial 3D numerical model using a thermal recovery chemical flooding simulator to simulate the process of CO2 Huff-n-Puff. The activation energy and reaction enthalpy were calculated based on the reaction kinetics and thermodynamic models. The interpolation parameters were determined through history matching a series of surfactant core flooding results with the simulation model. The effect of compound surfactant on the Huff-n-Puff CO2 process was demonstrated via a series of sensitivity studies to quantify the effects of a number of operation parameters including the injection volume and mole concentration of the reagent, the injection rate, the well shut-in time, and the oil withdrawal rate. Based on the daily production rate during the period of Huff-n-Puff, a desirable agreement was shown between the field applications and simulated results

Property degradation of seawater sea sand cementitious mortar with GGBFS and glass fiber subjected to elevated temperatures

Effects of ground granulated blast-furnace slag (GGBFS) and glass fiber on the property degradation of seawater sea sand mortar (FSSM) after elevated temperature exposure were investigated in this study. The physical properties and mechanical strength of FSSM were compared with that of cementitious mortar prepared with demineralized water and river sand (FRRM). The results showed that when the mortars were exposed to normal temperature, the compressive strength of FSSM was higher than that of FRRM. GGBFS increased both the compressive and flexural strengths of FSSM, while glass fiber increased the flexural strength but slightly decreased the compressive strength. The maximum flexural strength of FSSM was achieved with 1 wt.% glass fiber and 30% GGBFS. After exposed to temperatures of 200 °C and 400 °C, the flexural and compressive strength losses of FSSM were lower than that of the corresponding FRRM, while the FSSM with glass fiber exhibited more compressive strength loss but less flexural strength loss compared to the FRRM. Additionally, GGBFS could densify the microstructure of FSSM, and decrease the losses of flexural and compressive strength after exposed to elevated temperatures. The calcium aluminosilicate hydrate (C–A–S–H) gels with higher ratios of Si/Ca and Al/Ca in the FSSM with GGBFS were significantly more stable at the temperature of 700 °C compared to the calcium silicate hydrate (C–S–H) gels with lower ratios of Si/Ca and Al/Ca in the FRRM or FSSM without GGBFS. Therefore, it can be included that the high temperature or fire resistance of FSSM can be improved by glass fibers and GGBFS.This article is published as Qu, Fulin, Wengui Li, Zhuo Tang, and Kejin Wang. "Property degradation of seawater sea sand cementitious mortar with GGBFS and glass fiber subjected to elevated temperatures." Journal of Materials Research and Technology 13 (2021): 366-384. DOI: 10.1016/j.jmrt.2021.04.068. Copyright 2021 The Author(s). Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission

A Facility Layout Algorithm for Logistics Scenarios Driven by Transport Lines

The layout of facilities in a logistics scenario involves not only the working facilities responsible for processing materials but also the transport lines responsible for transporting materials. The traditional facility layout methods do not take into account the transportation facilities nor calculate the material handling cost by Manhattan distance, thus failing to fulfill the actual requirements of industrial logistics scenarios. In this paper, a facility layout algorithm framework MOSA-FD driven by transport lines is proposed. A multi-objective simulated annealing (MOSA) algorithm is designed for both material handling cost (MHC) and transport facility cost (TFC) objectives. Then, a force-directed (FD) algorithm is applied to correct the unreasonable solutions according to the material transport lines in the logistics workshop, and a better solution is quickly obtained. Finally, by comparing the results with those of other metaheuristic multi-objective algorithms, the acceleration of the force-directed algorithm in this layout problem is demonstrated in experimental instances of different scales, and our method, compared to the MOSA algorithm, can reach optimal ratios of 36% and 80%, respectively, on the multi-objective

Robust and Efficient CPU-Based RGB-D Scene Reconstruction

3D scene reconstruction is an important topic in computer vision. A complete scene is reconstructed from views acquired along the camera trajectory, each view containing a small part of the scene. Tracking in textureless scenes is well known to be a Gordian knot of camera tracking, and how to obtain accurate 3D models quickly is a major challenge for existing systems. For the application of robotics, we propose a robust CPU-based approach to reconstruct indoor scenes efficiently with a consumer RGB-D camera. The proposed approach bridges feature-based camera tracking and volumetric-based data integration together and has a good reconstruction performance in terms of both robustness and efficiency. The key points in our approach include: (i) a robust and fast camera tracking method combining points and edges, which improves tracking stability in textureless scenes; (ii) an efficient data fusion strategy to select camera views and integrate RGB-D images on multiple scales, which enhances the efficiency of volumetric integration; (iii) a novel RGB-D scene reconstruction system, which can be quickly implemented on a standard CPU. Experimental results demonstrate that our approach reconstructs scenes with higher robustness and efficiency compared to state-of-the-art reconstruction systems