Experimental study on soil improvement by electrochemical injection of calcium chloride solutions with time interval.

An improved electroosmotic method is proposed in this paper to enhance the non-uniform effect and efficiency of electroosmotic process. Such method is electroosmotic flow with injection of calcium chloride through the anode, followed by injection through the central tube (a tube at the midpoint between the anode and the cathode) with a suitable time interval between injections. Experimental results indicate that using this method can significantly improve the non-uniform reduction in water content throughout the soil, mitigate the formation of cracks in the anode section, and therefore considerably inhibit the increase in the electric resistance. After treatment, the drained water could be raised to 3.59 times more than that of pure electroosmotic flow, and 1.3 times that of simultaneous injection through both the anode and the central tube with considerably slight increase in power consumption. Moreover, the area of cementation was also expanded, approximately twice larger than that of pure electroosmotic flow and one and a half that of simultaneous injection. It is also worth noting that the proposed method performs better with the same power consumption. The results demonstrate that electroosmotic flow with a suitable time interval between injections could improve the efficiency of electroosmotic process and expand the treatment region in soils, hence can be a promising and economic technique for soil improvement in practical engineering.

Analysis of the Current Situation of Teaching and Learning of Ideological and Political Theory Courses by Deep Learning.

The objectives are to solve the problems existing in the current ideological and political theory courses, such as the difficulty of classroom teaching quality assessment, the confusion of teachers' classroom process management, and the lack of objective assessment basis in teaching quality monitoring. Based on Artificial Intelligence (AI) technology, a designed evaluation method is proposed for teachers' classroom teaching and solves some problems such as high system cost, low evaluation accuracy, and imperfect evaluation methods. Firstly, the boundary algorithm system is introduced in the research, and the Field Programmable Gate Array (FPGA) by deep learning (DL) is used to accelerate the server hardware network platform and equipped with pan tilt zoom (PTZ) and manage multiple AI + embedded visual boundary algorithm devices. Secondly, the network platform can manage the PTZ and focal length of Internet protocol (IP) cameras, measure, and capture face images, transmit data, and recognize students' face, head, and body postures. Finally, classroom teaching is evaluated, and students' behavioral data and functions are designed, debugged, and tested. The research results demonstrate that the method overcomes the problem of high system cost through edge computing and hardware structure, and DL technology is used to overcome the problem of low accuracy of classroom teaching evaluation. Various indicators such as attendance rate, concentration, activity, and richness of teaching links in classroom teaching are obtained. The method involved can make an objective evaluation of classroom teaching and overcome the problem of incomplete classroom teaching evaluation.

Laboratory Study on Improvement of Expansive Soil by Chemically Induced Calcium Carbonate Precipitation.

This paper proposes the use of calcium carbonate (CaCO3) precipitation induced by the addition of calcium chloride (CaCl2) and sodium carbonate (Na2CO3) solutions as a procedure to stabilize and improve expansive soil. A set of laboratory tests, including the free swell test, unloaded swelling ratio test, unconfined compression test, direct shear test, scanning electron microscopy (SEM) test, cyclic wetting-drying test and laboratory-scale precipitation model test, were performed under various curing periods to evaluate the performance of the CaCO3 stabilization. It is concluded from the free swell tests and unloaded swelling ratio tests that the addition of CaCl2 and Na2CO3 can profoundly decrease soil expansion potential. The reduction in expansion parameters is primarily attributed to the strong short-term reactions between clay and stabilizers. In addition, the formed cementation precipitation can decrease the water adsorption capacity of the clay surface and then consequently reduce the expansion potential. The results of unconfined compression tests and direct shear strength tests indicated that the addition of CaCl2 and Na2CO3 has a major effect on geotechnical behavior of expansive soils. Based on the SEM analyses, new cementing crystalline phases formatted by sequentially mixing CaCl2 and Na2CO3 solutions into expansive soil were found to appear in the pore space, which results in a much denser microstructure. A laboratory-scale model test was conducted, and results demonstrate the effectiveness of the CaCO3 precipitation technique in stabilizing the expansive soil procedure. The test results indicated that the concentration of CaCl2 higher than 22.0% and Na2CO3 higher than 21.2% are needed to satisfactorily stabilize expansive soil. It is proposed to implement the precipitation technique in the field by the sequential permeation of CaCl2 and Na2CO3 solutions into soils in situ.

FCG-ASpredictor: An Approach for the Prediction of Average Speed of Road Segments with Floating Car GPS Data.

The average speed (AS) of a road segment is an important factor for predicting traffic congestion, because the accuracy of AS can directly affect the implementation of traffic management. The traffic environment, spatiotemporal information, and the dynamic interaction between these two factors impact the predictive accuracy of AS in the existing literature, and floating car data comprehensively reflect the operation of urban road vehicles. In this paper, we proposed a novel road segment AS predictive model, which is based on floating car data. First, the impact of historical AS, weather, and date attributes on AS prediction has been analyzed. Then, through spatiotemporal correlations calculation based on the data from Global Positioning System (GPS), the predictive method utilizes the recursive least squares method to fuse the historical AS with other factors (such as weather, date attributes, etc.) and adopts an extended Kalman filter algorithm to accurately predict the AS of the target segment. Finally, we applied our approach on the traffic congestion prediction on four road segments in Chengdu, China. The results showed that the proposed predictive model is highly feasible and accurate.

Loading Cu-doped magnesium oxide onto surface of magnetic nanoparticles to prepare magnetic disinfectant with enhanced antibacterial activity.

In this article, Cu-doped magnesium oxide was loaded onto the surface of Fe3O4 magnetic nanoparticles via a hydrophilic carbon intermediate layer to synthesize Fe3O4@C@MgO-Cu magnetic composite. The potential application as disinfectant in water purification was investigated by examining the antibacterial activity of the Fe3O4@C@MgO-Cu composite toward Gram negative Escherichia coli and Gram positive Staphylococcus aureus. The practical bactericidal efficiency in inactivation experiment was also studied and the copper doping amount was optimized. The results show that the as-obtained magnetic composite, with good dispersion and typical multilayer structure, exhibited high antibacterial activity to both strains and the Cu-doping improved the antibacterial performance significantly. Moreover, an increasing bactericidal ability of the nanocomposite was observed with the increasing Cu-doping amount and 312.5mgL-1 of Fe3O4@C@MgO-Cu disinfectant with a 1.5% Cu-doping amount (wt% of MgO) could inactivate 99% of the tested bacteria in normal saline solution within 60minutes. The Fe3O4@C@MgO-Cu composite, with a high magnetic saturation value of 29.07emug-1, can be readily recovered from matrix solution for reuse with an external magnet, which simplified the disinfection operation greatly and avoided the waste of disinfectant.