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This paper introduces the evolution and development process of coal fire and its features. This paper expounds on the detection mechanism and research progress of four layers of space exploration technology divided according to the different spatial positions of detectors. The technologies include underground, surface, aerial, and aerospace detection methods. The paper analyzes the advantages and disadvantages of the above four detection technologies. The existing research problems are pointed out. ① The detection precision is insufficient and it is difficult to accurately delineate the acquisition range. ② The detection technology is outdated, and it is difficult to accurately detect high-temperature points in fire areas. ③ The detection method is single and cannot accurately determine the specific information of underground coal fire combustion. In view of the new features of underground coal fire, such as concealment, coupling and complexity, the development directions of underground coal fire detection technology are proposed. ① The detection instrument data needs to be finely processed, so as to improve the sensitivity of magnetic difference to temperature, the detection precision of the resistivity method, the feature extraction rate and the result precision of the infrared detection method. ② It is suggested to utilize high-tech equipment to serve coal fire detection technology. ③ It is suggested to improve the collaborative utilization of multi-level detection technology. Firstly, large-scale fire detection is carried out using the four th level aerospace remote sensing technology to obtain the basic spatial distribution features of underground coal fire anomalies. Secondly, further exploration is carried out using the third level aerial remote sensing detection technology to obtain the specific spatial distribution of underground coal fires. Finally, a more detailed distribution of high-temperature points in the coal field fire area is obtained by using the surface detection technology and underground detection technology at the second level and the first level to supply and verify. ④ It is suggested to develop 3D visual and dynamic monitoring and early warning of coal field fire areas. 3D inversion and joint inversion imaging are performed by use of data from four different levels of detection technology. Based on the imaging results, visual monitoring and early warning of coal fire development and spread are carried out, so as to achieve active prevention and control of underground coal fine disasters.

To research the influence of moisture on the oxidation characteristics of coal, the coal spontaneous combustion experiment was carried out to determine the composite index gas that can predict the spontaneous combustion of coal, and then the temperature-programing experiments were carried out to test the changes of composite gas index during the oxidation process of coal samples with different moisture content, the change law of the composite gas index generated under the influence of moisture was researched, and the influence law and mechanism of coal sample moisture content on coal oxidation characteristics were discussed. The results of research show that the spontaneous combustion temperature of coal has an obvious relationship with CO/CH4, C2H6/CO, CO/CO2 and Graham index. The influence moisture content on the temperature rise process of coal oxidation presents different stage characteristics at different temperatures: at 30−120 ℃, moisture has both catalytic and inhibitory effects on the coal oxidation reaction, and the inhibitory effect is dominant, showing the moisture content with the best inhibitory effect is 20%; at 120−140 ℃, the inhibitory effect of moisture on coal oxidation reaction is reduced, and moisture participates in the coal oxidation reaction as a reactant, and then shows the promotion effect of moisture on coal oxidation. At this time, the moisture in the coal oxidation reaction is mainly chemically promoted, and the moisture content with the best promotion effect is 10%; at 120−140 ℃, the original pore volume of the coal sample increases due to the evaporation of water and new coal samples are produced. The tiny pores become more conducive to the occurrence of coal oxidation reaction, and then show an indirect promotion effect on the reaction. The moisture content with the best promotion effect is 15%. It was finally determined that under the influence of moisture, the composite index gas that can more accurately predict the spontaneous combustion of coal are CO/CH4, C2H6/CO and Graham index. The research results can enrich the parameters of actual coal spontaneous combustion on site, increase the mining safety of high-humidity coal seams and the accuracy of spontaneous combustion prediction, and effectively reduce and prevent the occurrence of coal spontaneous combustion accidents.

The detection of corona-related defects in transmission lines has been included in the work of transmission line defect detection. Ultraviolet detection technology has gradually been widely applied in the field of corona discharge detection. However, the current research on the application of ultraviolet detection technology in transmission lines is relatively simple and mainly limited to using changes in the photon count to determine whether corona discharge has occurred. To address this, this study used a mini corona cage to simulate transmission lines and measured the changes in the photon count, spot area, and corona current in the corona inception process of different types of smooth, stainless-steel conductors. This study also investigated the variations in the photon count and spot area depending on conductor corona intensity, ultraviolet imager gain, and observation distance. The results show that the photon count and spot area can, to some extent, reflect the intensity of corona discharge. Both the photon count and spot area exhibited quadratic relationships with the voltage. As the observation distance increased, both the photon count and spot area showed exponential decay. The photon count exhibited a trend of initially increasing, then decreasing, and finally increasing again with the increase of gain, while the spot area showed exponential growth with increasing gain. The photon count and spot area can complement each other to identify and characterize the intensity of corona discharge.

The sudden load changes impact power grids by frequency and power oscillations. In order to distinguish the complex and massive abnormal user load data， this paper proposes a method combining multiple features and LOF （local outlier factor） algorithm. Firstly， the statistical characteristic mean value， standard deviation， waveform characteristic dispersion coefficient， kurtosis， waveform factor and pulse factor of load data are extracted， and the effective features are obtained through dimensionality reduction of PCA （principal component analysis）. Furthermore， the LOF algorithm is used to detect abnormal user load data every day. This detection algorithm is used in the Zhejiang power data center based on Alibaba cloud. The results show that it can detect users with abrupt load changes in massive measured data at fixed times of every day and realizes online detection with high accuracy.

In order to more accurately predict the development process of coal spontaneous combustion and take effective preventive measures in time, we used a self-developed temperature-programming experimental device, took fresh coal samples from Qingshuiying in Ningxia and Dafosi Coal Mines as the research objects, and obtained the gas volume fraction and gas components produced by two experimental coal samples at different oxidation temperatures, and analyzed the gas variation law of experimental coal samples at low temperature oxidation stage, and determined the characteristic temperatures of the two experimental coal samples. At the same time, three methods of multi-parameter index method, gas growth rate analysis method and Graham coefficient are used to comprehensively analyze and predict the oxidation process of experimental coal samples. The results show that the CO, CO2, CH4, C2H6, C2H4 gases are all positively correlated with temperature during the experiment; CO gas, CO2 gas, and the second fire coefficient R2 can be used as the main gas indicators for predicting the spontaneous combustion of the two experimental coal samples; CH4, C2H6, C2H4 gases, the first fire coefficient R1 and the third fire coefficient R3 are used as auxiliary gas indicators; the critical temperature of Qingshuiying coal sample is 60-80 ℃; dry cracking temperature is 110-125 ℃. The critical temperature of Dafosi coal sample is 60-75 ℃; the dry cracking temperature is 80-100 ℃.

In order to investigate the microscopic physicochemical properties and macroscopic coal-oxygen complex thermal effects in the low-temperature oxidation of coal under gas atmosphere, different metamorphic coal and secondary oxidized coal samples as research objects were selected in this paper. Fourier infrared spectrometer and C80 microcalorimeter were employed to study the changes of physicochemical structural properties, kinetic parameters and thermal effects in the low-temperature oxidation of coal under different gas atmospheres. By analysing the microstructure and macroscopic exothermic characteristics of different gas content during coal spontaneous oxidation, the ultimate influence of gas on the oxidation characteristics of coal was clarified. The results show that gas delays the low-temperature oxidation process of coal by inhibiting the relative content of key active groups in the low-temperature oxidation process of coal. 4% gas has the most obvious inhibitory effect. The degree of inhibition on the four active groups is: oxygen-containing functional groups (66.5%) > Aromatic hydrocarbons (47.0%) > Aliphatic hydrocarbons (29.7%) > Hydroxyl (24.7%). In the rapid exothermic stage, due to the large adsorption capacity of coal to gas molecules, gas occupies the adsorption sites in coal molecules, which hinders the process of coal-oxygen recombination reaction, resulting in the exothermic effect being suppressed by gas; at the same time, gas content significantly affects coal oxygen. The amount of activation energy required for the recombination process. For high metamorphic non-stick coal, lean coal and anthracite, gas has a more significant inhibitory effect on its low temperature oxidation reaction; it has less effect on low metamorphic long flame coal. For secondary oxidized coal samples, the inhibitory effect of gas on coal samples increases with the increase of gas content, while the effect of gas on primary oxidized coal samples decreases as the degree of metamorphism decreases, and the degree of inhibition when the gas content is 2% is stronger than 4%. The results of the work have great significance to the theoretical study of the prevention and control of the coupling of gas and coal spontaneous combustion causing accidents.

With the increase of coal mining intensity in mines, the tendency of coal to spontaneous combustion increases gradually. Due to the existing coal mine spontaneous combustion fire beam tube chromatography monitoring system has the problems of easy distortion of gas detection, long analysis period and easy pollution of gas sample, it cannot provide an effective scientific basis for the prevention and control of coal mine spontaneous combustion fire. In this paper, based on the traditional beam tube chromatography system, we combine micro gas chromatography detection with data network transmission and other high technologies to develop an intrinsically safe underground micro chromatography and beam tube positive pressure gas delivery pump station, forming a coal mine spontaneous combustion fire monitoring system based on micro chromatography and positive pressure gas delivery technology. The system is capable of analyzing 10 gas components simultaneously within 2 to 3 min with relative standard deviation ≤1.54%, relative accuracy up to 1.0% and lower detection limit up to 1×10-6. It improves the reliability and stability of the coal mine spontaneous combustion fire monitoring system, realizes real-time and accurate prediction of spontaneous combustion fires, and guarantees the safe production of coal mines.

The dynamic change of goaf determines the complexity between limit parameters of coal spontaneous combustion and its influencing factors. In order to achieve accurate prediction of limit parameters of coal spontaneous combustion, the grey correlation analysis was introduced to quantitatively analyze the correlation between the superior intensity limit of air leakage and its influencing factors. Further, the key parameters of support vector regression(SVR) were optimized by improved particle swarm optimization (IPSO), and the prediction model on limit parameters of coal spontaneous combustion in goaf was established. Taking the superior intensity limit of air leakage as an example, the standard PSO-SVR and the multiple linear regression model (MLR) were respectively established. Moreover, the models mentioned above were used for predicting the superior intensity limit of air leakage and compared with the existing method of variable-step grid search for optimizing SVR parameters and the neural network. The results show that the grey synthetic degree between the inferior thickness limit of coal and the superior intensity limit of air leakage was the largest, the oxygen concentration and the coal temperature were the second, and the exothermic intensity and the distance of the goaf from the working face were the smallest. The nonlinear relationship between limit parameters of coal spontaneous combustion and its influencing factors is more remarkable than the linear relationship. SVR has stronger nonlinear processing ability than neural network method. The relative error between predicted values and real values of IPSO-SVR model is within 2.6%, and its prediction accuracy is better than other four models. It is helpful for the key parameters optimization by IPSO to improve the prediction precision of SVR model. The IPSO-SVR method is effective for the prediction on limit parameters of coal spontaneous combustion.

The spontaneous combustion of coal in the goaf can easily lead to waste of resources and environmental pollution, and at the same time, it can cause major catastrophic accidents such as gas combustion and dust explosion, resulting in property losses and casualties. In order to further improve the coal spontaneous combustion “preventing-suppressing-extinguishing” coordinated fire-fighting technology and promote the green mining of coal resources in our country, the reasons and influencing factors of coal spontaneous combustion in goaf were analyzed, this paper summarizes the existing fire prevention, suppression and fire extinguishing technologies in goaf, comparatively analyzes the advantages and disadvantages of various types of “preventing-suppressing-extinguishing” technologies, and solves the problems existing in the process of coal spontaneous combustion in the goaf.

Coal spontaneous combustion disaster is one of the main disasters in the process of coal mining. The acquisition of multi-source three-dimensional parameters of spontaneous coal combustion, the in-depth analysis of data, the establishment of mathematical models and accurate prediction are the basic guarantee for the production of coal mining enterprises. This paper summarizes the basic status of research and application of coal spontaneous combustion monitoring and early warning from three aspects: monitoring methods, mathematical analysis and prediction methods of coal spontaneous combustion multi-source three-dimensional parameters, and further prospects the future development direction of coal spontaneous combustion intelligent monitoring and accurate prediction.

In order to master the relationship between the key active groups of weathered coal and oxidized coal at the characteristic temperature of coal spontaneous combustion, this paper takes the fresh coal as the reference coal to compare and analyze the microstructure of weathered coal and oxidized coal. Firstly, the relative content of active functional groups and characteristic structural parameters of weathered coal and oxidized coal in the initial state were analyzed by Fourier transform infrared spectroscopy, the variation laws of four main active functions under characteristic temperature were determined, and the differences of different active groups between weathered coal and oxidized coal were semi quantitatively analyzed. The key active groups affecting the difference of natural ignition between weathered coal and oxidized coal are revealed. Through the programmed temperature rise experiment of coal spontaneous combustion, the release characteristics of index gas concentration of weathered coal and oxidized coal were analyzed, and the evolution and migration of key functional groups at characteristic temperature were verified. The results show that the content of CO produced by oxidized coal was higher than that of weathered coal due to the different content of C-O-C in oxygen-containing functional groups, while the content of C2H6 produced by weathered coal was higher than that of oxidized coal due to the different asymmetric stretching vibration of methyl and methylene in aliphatic hydrocarbons.

The selection of signal frequency in acoustic temperature measurement technology is the key to improve the accuracy of temperature measurement. In order to explore the optimal propagation frequency of low-frequency sound waves in loose coal, lignite, coking coal, and anthracite are used as the research objects. The acoustic loss of three coal samples under six particle sizes（0.9 mm to ＜3 mm, 3 mm to ＜5 mm, 5 mm to ＜7 mm, 7 mm to 10 mm, 9 mm to 10 mm and larger than 10 mm） by using the acoustic loss test system is tested. The experimental results show that the sound transmission loss of three coal samples presents a wave-like rising shape with the increase of the sound wave frequency. Compared with coal samples of other particle sizes, the sound transmission loss of coal samples in the range of 0.9 mm to ＜3 mm is the largest. As the particle size of coal samples increases, the sound transmission loss of coal samples continues to increase, and the sound wave frequency corresponding to the lowest point of sound transmission loss also increases. The degree of coal sample deterioration has no obvious regularity in the influence of sound transmission loss. The sample size is the main factor that affects the change of the sound transmission loss of the coal sample, and the sound waves mainly propagate along the gaps between the particle sizes of the loose coal. By comparing and analyzing the maximum and minimum values of sound transmission loss, there is a maximum value between 250 Hz to 600 Hz and 900 Hz to 1 600 Hz about the sound transmission loss of coal samples of different particle sizes, and the maximum sound transmission loss range is between 4.66 dB and 7.64 dB. By testing the sound transmission loss in the low-frequency sound waves of the mixture of three coal samples, it is determined that the optimal sound transmission frequency range in the loose coal is 600 Hz to 900 Hz.

To investigate the oxidation combustion heat effect and thermokinetic behavior of lean coal, the pulverized coal samples were tested using C80 micro caloric system and thermogravimetric experimental device, respectively. The thermal effects of lean coal samples during the low-temperature oxidation and oxidation combustion were analyzed, and the influence of the heating rate on the combustion process of lean coal was also studied. In addition, the apparent activation energy and the most probable mechanism function of the coal sample during the combustion process were analyzed. The results indicated that the low-temperature oxidation process of lean coal pulverized coal could be divided into slow oxidation, accelerated oxidation and fast oxidation stages. Moreover, the five characteristic temperature points during the oxidation combustion of pulverized coal were determined by the variations of TG/DTG curves; with the increase of the heating rate, the TG and DTG curves of the coal sample shifted to the high temperature zone, and the peak value of the DTG curve increased with the ignition temperature increased; the apparent activation energy of coal sample in the pyrolysis combustion stage described a trend of first increasing and then decreasing with the increase in the conversion rate. The maximum apparent activation energy were observed when the conversion rate is 0.2, which was 32.4 kJ/mol; heating rates had tiny effect on the most probable mechanism function of the oxidation reaction. The most probable mechanism functions of the reaction under the four heating rates were all basically in line with the A-E equation random nucleation and subsequent growth model, and the peak value of the function curve increased with the heatingrate increased.

In order to solve the problems of low detection precision and slow detection speed of existing coal block detection methods on belt conveyor in underground coal mine, an improved YOLOv4 model integrating lightweight network and dual attention mechanism is proposed, and it is applied to coal block detection of belt conveyor. The improved YOLOv4 model uses K-means clustering algorithm to re-cluster the prior frames, so that the prior frames are more suitable for the size of the detected target. The model improves the backbone network structure by introducing the MobileNet lightweight network model to reduce the amount of model parameters and calculations, and improve the detection speed. A convolution block attention module with dual attention mechanism is embedded to improve the sensitivity of the model to target characteristics, suppress interference information and improve the precision of target detection. The experimental results show that the improved YOLOv4 model can detect coal blocks of different sizes accurately. Compared with the YOLOv4 model, the improved YOLOv4 model weight file is reduced by 36.46%, the accuracy rate is increased by 2.16%, the recall rate is increased by 20.4%, the average accuracy is increased by 14.37%, the missed detection rate is decreased by 16%, the detection speed is increased by 19 frames/s, the processing time for a single image is reduced by 1.31 s, which improves the detection precision and speed of coal block detection.

Quantitative prediction of mineral resources based on multi-information fusion is the leading topic of resource potential prediction, in which the deep mining of different geological background information and geochemical data is the key problem and still challenging. In this study, we analyzed the spatial distribution characteristics of main metallogenic and associated elements such as Au, Ag, Mn, Cu, Pb, Zn, Sn and Sb in 60767 geochemical samples on the platforms like ArcGIS and GeoDAS, by summerzing the geological background information and metallogenic controlling factors of each tectonic unit in Guangxi. Based on the GeoDAS paltform, through IDW interpolation, S-A anomaly decomposition, principal component analysis and other technologies, the data from the layers with geochemical component element anomaly, gravity and aeromagnetic anomaly and the buffers at the intersection of magmatic rock and fault were used as the training points for the utilization of the fuzzy weights of evidence. A posteriori probability map was drawn up to delineate the favorable metallogenic areas for Carlin-type gold deposit and fracture zone altered gold deposit. This study is of great significance to the application of new metallogenic theories and evaluation techniques in the evaluation or zoning of mineral resources potential.

To promote the efficient utilization of coal resources and develop the green, economic, and scientific fire-fighting technologies, current situation of coal fire disasters in China was briefly introduced, and the basic theoretical research status of coal spontaneous combustion (CSC) mechanism and characteristics are explained. A technical scheme for fire prevention at different stages is proposed. Then, this paper summarizes the technological progresses of CSC prevention, control, and fire extinguishment. Among them, prevention and control are mainly based on plugging wind, grouting and glue injection, and fire extinguishment technology is changed from water injection and grouting to inert gas. Finally, the main problems and challenges of current fire prevention and control technology, including acquisition of characteristic information of coal spontaneous combustion fire, implementation of detection means, location of fire sources, research and development of fire protection materials and equipment are summarized. The prevention and control of coal spontaneous combustion fire should follow the principles of precision, speed and intelligence, so as to realize the fundamental change from passive control to active prevention and control of coal spontaneous combustion fire.

55% pirimiphos-methyl EC mixed ultrapure water by proportion of 1∶2, was sprayed to the surface and the upper space of grain in large warehouse by Ultra-low-volume sprayer. Our study was performed twice at the end of April 2019 and the end of July 2019 respectively. Stored-grain pest protection layer was formed on the surface of grain bulk to continuously prevent the grain from suffering pest infringement. At the same time, the temperature controlled by air conditioner of warehouse was lower than 25 ℃. In this way, we can maximize the effect of pirimiphos-methyl protective layer on insect pests. By using pirimiphos-methyl will significantly reduce the amount of aluminium phosphide used in large warehouse and the intensity of labor. Because of the low toxicity, residue, cost and environmental friendly of pirimiphos-methyl, we concentrate on replacing aluminium phosphide with pirimiphos-methyl to achieve the goal of warehouse fumigation-free all year round.

[Objectives] An energy management optimization strategy is proposed which considers the limitation of a ship's power system operation and greenhouse gas(GHG) emissions.[Methods] This strategy uses the differential evolution algorithm and real number code to optimize the dispatching speed of the ship,start and stop state of the generators and power distribution of the generator set with minimum consumption as the goal. These three plans can ensure compliance with environmental limits while reducing fuel consumption and ensuring efficiency.[Results] Taking the actual measured data of a cruise ferry as an example,the operating cost of the initial plan(plan 1)is 36 960.5 m.u while the operating costs of plan 2 and plan 3 are 36 938.1 m.u and 35 888.3 m.u respectively,showing a decrease of 0.06% and 2.90% when compared with the initial plan.[Conclusions] On the precondition that the optimal design method meets the limitations of the ship's generator,diesel engine operation,GHG limit and arrival distance,it can be seen that the ship's speed and propulsion curve become relatively stable,the figure tends to be trapezoidal and the efficiency of the ship's power system and fuel economy are significantly improved,while the amount of greenhouse gas emissions is simultaneously reduced.

Hot-rolled bimetallic composite plates are widely used because of their excellent properties. In the recent years, the enhancement of the combined performance of hot-rolled bimetallic composite plates has gained the attention of the industry. The molecular dynamics simulations were employed to assess the high-temperature combined performance of 316L/Q345R bimetallic plate systematically. The hot-compression process of the 316L/Q345R system was simulated on its atom structure model. The potential functions of the embedded-atom method were employed to describe the interaction between Fe, Cr, and Ni. The effects of temperature and compressive strain rate on the mechanism of the hot-compression deformation and the thickness of the diffusion layer were analyzed. The influence of adding a metal layer on the interface bonding performance was also discussed. The results show that increasing the temperature up to the composite melting point leads to the formation of a thicker diffusion layer at the bimetallic interface. However, an increase in the strain rate reduces the thickness of the diffusion layer, because the diffusion and compression time of the atoms shortens as the strain rate increases. The influence of the addition of a Ni or a Cr layer on the combined performance was investigated. The thickness of the diffusion layer of the bimetallic interface was increased by 134.5% when a lattice thickness Ni layer was added in the bimetallic interface; however, the addition of a Cr layer did not improve the combined performance. This study provides new insight into the factors that directly influence the performance of hot-rolled bimetallic composite plates.

There are some problems in the thermal system of Huabei Oilfield, such as high energy consumption, high operation cost and poor production safety. With more stringent requirements for energy conservation and emission reduction, it is particularly important to replace fuel oil projects and improve the efficiency of heating system.The utilization of waste heat and waste heat resources in Huabei Oilfield and the application conditions of various heat pump technologies were investigated, according to the characteristics of large amount of sewage and high temperature produced by crude oil dehydration in Huabei Oilfield. Aiming at the characteristics of large amount of sewage and high temperature produced by crude oil dehydration in Huabei Oilfield, Pilot Application of Optimized Extracted Water Source Heat Pump Technology, the research results are applied to the the He Yi Station in the third oil production plant, estimating the scale and benefit of saving, finally, the purpose of reducing cost and increasing efficiency is achieved, and the data basis and technical guidance for energy saving renovation of thermal system in the future are improved.

Based on the first national water cultural heritage survey of existing water conservancy, this paper sorts cultural heritage status quo and the main problems; through the status and value analysis, protection strategy recommendations are proposed.

Hetao Irrigation District in Inner Mongolia was built in the Qin and Han Dynasties and has been fulfilling its good irrigation function. Through field investigation, data collection and visits to experts, scholars and management departments, this paper summarizes the historical evolution and composition of irrigation works heritage in Hetao Irrigation District and its historical, social and scientific values.

Hydroponic cultures were conducted to compare the aluminum (Al) tolerance among different rice (Oryza sativa L.) varieties, including indica, japonica and their hybrids. The results showed that the root growth of rice plant was inhibited in different degrees among Al treated varieties. The Al tolerance observed through relative root elongation indicated that five japonica varieties including Longjing 9, Dharial, LGC 1, Ribenyou and Koshihikari were relatively more tolerant than indica varieties. Most indica varieties in this study, such as Aus 373 and 9311 (awnless), were sensitive to Al toxicity. The Al tolerance of most progenies from japonica × indica or indica × japonica crosses was constantly consistent with indica parents. The differences of Al tolerance among Longjing 9 (japonica), Yangdao 6 (indica) and Wuyunjing 7 (japonica) were studied. Biomass and the malondial-dehyde content of Yangdao 6 under Al exposure decreased and increased, respectively, while there was no significant effect on those of Longjing 9 and Wuyunjing 7. Remarkable reduction of root activities was observed in all these three rice varieties. Significantly higher Al content in roots was found in Yangdao 6 compared to Longjing 9 or Wuyunjing 7.