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In artificial-source electromagnetic explorations, the shadow effects and source overprint effects are two of the key factors to affect the detection reliability. Compared with frequency-domain electromagnetic methods, the transient electromagnetic (TEM) shadow effect and source overprint effect are more complex, especially for the short-offset TEM (SOTEM) observed in the near-source region. However, there is less relevant research. Therefore, in this paper, we first realize 3D SOTEM simulations based on the vector time-domain finite element method, then further analyze the generation of SOTEM shadow effect and source overprint effect from view of the diffused electromagnetic fields, as well as their influence on ground horizontal electric field Ex and vertical induced voltage dBz/dt responses. Results show that the attraction or repulsion of the electrical inhomogeneity would affect the diffusion speed of the electromagnetic fields, which is the essential in the two source effects. Besides, from view of the ground Ex and dBz/dt responses, the relative anomaly of SOTEM shadow effect is almost twice those of the SOTEM source overprint effect, i.e. the SOTEM shadow effect is easier to record, especially for dBz/dt responses. In addition, owing to the shadow effect, SOTEM may fail to identify the real target anomaly, whereas the influence of the source overprint effect for recognizing the target anomaly mainly occurs on all-time dBz/dt responses and early-time Ex responses (before about 10 ms), that is, observing late-time SOTEM Ex responses can effectively avoid such influence. Hence, to fully ensure avoiding the influence of the source overprint effect, we suggest adopting high-power transmission to increase the late-time signal-to-noise ratio in field measurements.

Using multigeophysical exploration techniques is a common way for deep targets to be explored in complex survey areas. How to locate an unknown underground target using multiple datasets is a great challenge. The useful information in the multisource geophysical model can be extracted and fused with the help of data fusion, which also works well to correct the interpretation divergence brought on by expert experience, with image feature extraction being the key step in the fusion of the geophysical models. Traditionally, this method is often used for these kinds of geophysical images, but it significantly reduces the efficiency of feature extraction. As a result, we propose a novel method based on a transfer learning method to extract the features of multisource images. First, the ResNet50 network is used to extract the initial features of the images. Owing to the problems of feature redundancy and fuzzy features in initial features, Spearman and zero phase component analysis can be used to achieve feature reduction and enhancement, which can further improve the computational efficiency and fusion accuracy in fusion. Finally, the fusion image is obtained using fusion rules that we designed based on the current state. The algorithm's reliability is tested using field data from the Iliamna Volcano. The case study demonstrates the effectiveness of the proposed strategy, which also offers a novel way to locate subsurface targets.

A PVDF-HFP/graphene piezocatalytic film with a sandwich structure was prepared. Under the piezoelectric field of PVDF-HFP, the exposed graphene on the surface of the sandwich film provided the charges to react with the pollutants.

The concept of a smoke-ring in electromagnetic fields can be used to describe the spatial distribution and diffusion of electromagnetic fields with either frequency or time. This provides an intuitive basis for qualitative interpretation of artificial source electromagnetic measurement results. The existing discussions regarding this field of study have mainly focused on the smoke rings of a magnetic dipole or loop source. The smoke ring of the other commonly used grounded-wire sources in the time domain was investigated. The results show that the smoke ring of grounded-wire sources is more complex than that of magnetic sources. A grounded-wire source can generate induced current in both the horizontal and vertical directions. The horizontal induced current consists of two parts. At the early stage, when the source has just been turned off, there is a low-amplitude and fast-diffuse opposite return current. With time it becomes positive, and reaches a maximum, then decreases. The horizontal induced current maximum diffuses downward perpendicular to the surface, and the vertical induced current maximum diffuses at 45 degrees from the earth’s surface with a faster diffusion velocity, which is roughly 5 times that of the horizontal induced current. The smoke ring of the horizontal induced current more closely resembles the shape of a basin, while that of the vertical induced current is more like two separate jars. Finally, the respective imaging depths estimated based on the horizontal and vertical induced currents are 0.92 and 1.25 times the diffusion depth.

Coal spontaneous combustion is one of the disasters occurring in underground coal mines. As a typical case, the spontaneous combustion of broken coal left in the longwall gobs often happen which could greatly interrupt the normal mining production. Such concealed thermal event is featured as rapid development and difficulty in locating “hot” spots. If such spontaneous combustion fails to be timely prevented and controlled, a large amount of toxic gases (mainly CO) and smoke could flow and diffuse in the underground working sections, which could present safety hazards for coal miners. In this paper, based on an coal spontaneous combustion event happened in a Chinese gassy mine, the fire ratios derived from the gas composition data obtained through the tube bundle mine atmospheric monitoring system are used in determining the fire status. A comprehensive and collaborative fire extinguishing effort including inert gas injection, underground pressure balance, and sealing enhancement are made to control the fire progress. Simultaneously, the effects of such works to control the spontaneous combustion event have also been quantified using the fire ratios to justify again. Finally, the danger of coal spontaneous combustion in gob is eliminated, and the longwall panel is successfully re-opened for normal production.

Increasing expansion of China’s coal mine production leads to the increased storage pressure in current coal silos. Most of these coals are stored in open-air coal pile. Therefore, those coal piles have caused a series of environmental pollution problems, which includes endangering workers’ health and aggravating air pollution in the surrounding natural environment. Therefore, it is urgent to study and prevent the dust flying problem of coal pile. This paper, based on a single chemical dust suppressant, optimizes a new type of composite binder. This composite binder has advantages of dust suppression effect, relatively simple preparation process and the environmentally friendly agent. This paper is mainly divided into two parts: the study on the influencing factors of dust wetting and the development and application of related spraying systems. Through the energy spectrum analysis of scanning electron microscope and reverse osmosis method, it explores the dust wetting and suppression characteristics of the composite binder with different physical and chemical properties. The optimal application range of the composite binder are obtained. Finally, an automatic spraying system for dust suppression is designed. The composite binder developed in this paper is applied in the open-air coal yard and the results show that the composite binder studied in this paper has a good effect of dust suppression.

Increasing expansion of China's coal mine production leads to the increased storage pressure in current coal silos. Most of these coals are stored in open-air coal pile. Therefore, those coal piles have caused a series of environmental pollution problems, which includes endangering workers' health and aggravating air pollution in the surrounding natural environment. Based on a single chemical dust suppressant, this paper optimizes a new type of composite binder. The Composite binder has advantages of forming the crust on surface of coal pile. The artificial wind erosion simulation method is used to test the dust solidifying characteristics of the composite binder with different physical and chemical properties and the optimal application range of the composite binder is selected. Finally, the composite binder developed is applied in an open-air coal pile and the results show that the composite binder studied in this paper has a good effect of dust solidifying.

With the gradual development of deep mining, heat hazard has become an increasingly prominent problem, which poses a great threat to the coal mine production. In order to reduce the heat hazard effectively, it is necessary to investigate the temperature distribution characteristics and regulation of the surrounding rock of the mine tunnels. Based on field measurement data from a Chinese coal mine, the present study probes into the dynamic law of periodic variation of the heat regulation circle (HRC) in surrounding rocks, which is featured by the serious heat hazard, and further reveals the evolution characteristics of the physical range of HRC and the temperature field distribution. By analyzing field data, it can be concluded that a total of five typical distribution models of HRC of surrounding rocks are summarized. Influencing factors concerning thermophysical properties, thermal environment conditions of the stratum, and boundary conditions play important roles and affect the formation of such five models. A mathematical model of heat regulation and energy storage of surrounding rocks in a mine tunnel is proposed. Calculations of air temperature–regulating capability of HRC and evaluating its cooling storage capacity are also demonstrated. Using the HRC in rocks for cooling underground ventilation may be a good and green engineering practice for coal mines.

In underground mining operations, the overlying strata move, deform, and crack as the underground working face advances due to strata breakage, failure, and subsidence, forming a “vertical three zone” over the mined out area. The permeability of strata under mining changes differently in different zones. Therefore, studying the distribution of strata permeability is very important to obtain knowledge of gas migration pattern in the overlying strata in order to increase the gas extraction efficiency. In this study, a series of numerical models are developed to describe the overlying strata movement for three different zones. In detail, models for calculating the strata subsidence for fracture and bending zones and analyzing strata collapsing development for the caving zone are proposed based on the influence function method and mechanical analyses. In addition, on the basis of such models, a new comprehensive model to describe the strain‐porosity‐permeability of strata is developed. In the case study of applying such models in an underground mine, the reliability of the strata movement model is verified and the permeability change is also calculated, which gives a good guidance to design the location of gas drainage roadway practices in the future. The field engineering practice shows its good application.

Background Gastric cancer (GC) represents a major malignancy and is the third deathliest cancer globally. Several lines of evidence indicate that the epithelial-mesenchymal transition (EMT) has a critical function in the development of gastric cancer. Although plentiful molecular biomarkers have been identified, a precise risk model is still necessary to help doctors determine patient prognosis in GC. Methods Gene expression data and clinical information for GC were acquired from The Cancer Genome Atlas (TCGA) database and 200 EMT-related genes (ERGs) from the Molecular Signatures Database (MSigDB). Then, ERGs correlated with patient prognosis in GC were assessed by univariable and multivariable Cox regression analyses. Next, a risk score formula was established for evaluating patient outcome in GC and validated by survival and ROC curves. In addition, Kaplan-Meier curves were generated to assess the associations of the clinicopathological data with prognosis. And a cohort from the Gene Expression Omnibus (GEO) database was used for validation. Results Six EMT-related genes, including CDH6, COL5A2, ITGAV, MATN3, PLOD2, and POSTN, were identified. Based on the risk model, GC patients were assigned to the high- and low-risk groups. The results revealed that the model had good performance in predicting patient prognosis in GC. Conclusions We constructed a prognosis risk model for GC. Then, we verified the performance of the model, which may help doctors predict patient prognosis.

In recent years, the price of international nonferrous metals has undergone drastic fluctuations, which could exert significant shock effects on macroeconomic variables. Based on the perspective of resource security, this paper reveals the relationship between the nonferrous metal price shocks and China's macroeconomic variables by establishing a Dynamic Stochastic General Equilibrium (DSGE) model embedded with nonferrous metal consumption and means of production blocks. The model is based on the optimal decision-making behaviours of three departments that satisfy multiple constraints to realize optimal policy making. Furthermore, the Structural Vector Autoregression (SVAR) method is applied to verify the shock effects of nonferrous metal price and obtain more robust results. The Bayesian results show that there is consistency among nonferrous metal price shocks, consumer reference shocks, wage bonus shocks, technical shocks, and price-adjusted shocks. The impulse response function results indicate that the stimulation of an international nonferrous metal price increase would have significant positive impacts on the macroeconomic variables of investment, money supply, consumption and total output but negative effects on labour demand. In addition, the impulse responses of wage levels and the rate of inflation to nonferrous metal price shocks present obvious lagging effects.

Both the deviation position and the heading deviation of the AGV are generated by its deviation from the ideal guiding trajectory during the working process. in this paper, the method of inertial guidance and QR code are applied to correct this deviation of AGV. The position deviation and heading deviation are pretreated by performing Butterworth filtering and attitude calculation on the output of the inertial device. AGV accurately locates the four corners of QR code in the field of view and corrects the output of inertial devices to realize motion correction. The experimental results show that the posture deviation can be effectively eliminated before reaching to the next QR code positioning module. The positioning accuracy is less than 0.5 mm at a speed of 0.6 m/s.

In order to analyze the uplift bearing capacity of cone-cylinder foundation for transmission line in frozen soil regions, a series of reduced-scale modeling tests and numerical simulations are carried out. First, three reduced-scale cone-cylinder foundations with the same sizes, that are five times smaller than the prototype, are made and then loaded under uplift load at &minus, 5 &deg, C, &minus, 10 &deg, C, and &minus, 15 &deg, C, respectively. On this basis, the foundations of nine sizes are modeled and loaded by numerical simulation. The impact of three dimension factors, including the ratio of depth to bottom width (), the top diameter of the cone-cylinder (), and the bottom diameter of the cone-cylinder (), on the uplift bearing capacity of foundations have been investigated. The results reveal that, for cone-cylinder foundation, the uplift bearing capacity is obviously affected by the freezing temperatures and the foundation sizes. The capacity is negatively correlated with the former. Whereas the order of correlation with the latter is as follows: &lambda, D, and d based on the comprehensive results of range and variance analysis, but none of them are the significant factors, according to the F-test. Furthermore, three failure mechanisms of frozen soil are distinguished and named T-mode, V-mode, and U-mode, respectively. Based on the above results, the bearing mechanism of cone-cylinder foundation in frozen soil is elaborated in detail.