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Currently, most fiber optic microseismic monitoring systems in China are based on optical grating sensing technology. However, fiber optic grating wavelength demodulation limits the detection frequency and sensitivity of the system, and there are few successful cases of long-term, continuous and uninterrupted microseismic monitoring. In order to solve the above problems, a new type of all fiber microseismic monitoring system is proposed. Taking the monitoring of water inrush from the floor during the mining process of Pan'er Coal Mine 11023 working face as the engineering background, a comparison is made between the all fiber optic microseismic monitoring system and the ESG microseismic monitoring system. It is found that the all fiber optic microseismic monitoring system has the following advantages. The recorded waveform spectrum features are clearer, showing a high signal-to-noise ratio advantage. The monitoring range for disturbance depth is larger, and the remote monitoring effect is better. The distribution of seismic source positioning results is more reasonable and more in line with the actual mining situation of the working face. During the monitoring of the entire mining cycle of the working face, the relationship between the floor failure and microseismic activity in the fault abnormal area of the 11023 working face is analyzed. Near the fault and coal seam thinning abnormal area, the number and intensity of microseismic events increase. During the initial mining period of the working face, stress is concentrated and released. Due to the influence of mining, the floor is severely damaged. Relatively high energy events are mainly distributed in the floor of the fault anomaly area, with a depth of about 27 meters of damage to the floor. Micro seismic events do not form a line or accumulate in a plane below 60 meters of the 3 coal seam floor. It indicates that cracks have not expanded and no water conducting channels have been formed. The working face can be safely mined.

This study aims to address existing problems of complex stress conditions and difficulties in retaining roadway so as to achieve long-term stability of roadway surrounding rock in gob-side entry in thin coal seam. Specifically, we investigated the 4301 working face of Liangshuijing Coal Mine in Huisen Coal Industry of Shaanxi Province through theoretical analysis, numerical simulation and engineering practice, with an aim to study the failure characteristics and control countermeasures of surrounding rock of gob-side entry retaining in shallow buried "triple hard" thin coal seam, and analyse the influence of structural parameters of roadside support on roadway stability. The results show that 1)maintaining the roadway through roadside filling body requires sufficient support strength and appropriate shrinkage to the roof and ensuring the overall stability of the roadway; 2)the mechanical behaviour of high water filling material under uniaxial compression can be divided into four stages: "uniform compaction, elastic deformation, dynamic instability and deterioration failure". The numerical simulation results show that in increasing the width of the filling body, the maximum stress first increases, then decreases and then increases, and a stable bearing stress core appears at 1.6 m. Theoretical calculation shows that the optimal height of roof cutting is 10.7 m, and it offers the roof cutting scheme and parameters of shaped blasting. Engineering practice shows that there is no large deformation and no obvious stress concentration in the 60 m range behind the working face. The surrounding rock exhibits good overall control effect and stable structure, and the effect of retaining roadway meets the design requirements.

The rapid development of Internet technology and education informatization has accelerated people’s learning and changed their way of thinking and cognition. Colleges and universities have set up their cloud classroom learning platforms, and the mining and analysis of the platform’s learning data is, therefore, particularly important. In this study, the SOFM-based FCM algorithm is used to perform fuzzy clustering of user subjects with different learning behaviors, and then the FDMA algorithm is used to mine the association rules of users’ learning behaviors, and the fuzzy neural network algorithm is also used to predict the learning performance to achieve the fuzzy neural network algorithm based on the fuzzy neural network algorithm to analyze the learning behaviors of users in colleges and universities. On this basis, we are developing and implementing a system to monitor the learning behavior of college users to explore its practical value. Based on different user behaviors, college student users are divided into three categories: high motivation to study (29.8%), medium motivation to study (46.2%), and low motivation to study (24.0%). The confidence level of the mined fuzzy association rules takes the range of [0.84, 0.95], which has a high confidence level. The academic performance prediction model had an average relative error of 0.0278 and 0.0281, with better model fitting and higher accuracy of prediction. The success rate of user access to the system is high, and the system has been well-tested. This study provides a reference for the application of fuzzy neural network algorithms in the analysis of user learning behavior in universities.

High-altitude satellites are visible to more ground station antennas for longer periods of time, its requests often specify an antenna set and optional service windows, consequently leaving huge scheduling search space. The exploitation of reinforcement learning techniques provides a novel approach to the problem of high-altitude orbit satellite range scheduling. Upper sliding bound of request pass was calculated, combining customized scheduling strategy with overall antenna effectiveness, a frame of satellite range scheduling for urgent request using reinforcement learning was proposed. Simulations based on practical circumstances demonstrate the validity of the proposed method.

Taking the complex fault zone of group A coal mining in 12123 working face of Pan’er Mine in Huainan Mining area as the research object, a micro-seismic monitoring system was established to obtain the micro-seismic activity data in the structural development area, and the distribution of micro-seismic events and the response characteristics of source parameters during the deterioration of rock mass in the fault zone were analyzed, revealing the mechanical mechanism of the induced micro-seismic response. The results show that micro-seismic events show significant spatial and temporal characteristics with the relationship between mining and faults. The cumulative energy, b value, energy index and cumulative apparent volume change gradually with mining, which can effectively reflect the failure state of fault surrounding rock. Under the influence of “triangular isolated island area” of rock mass formed by mining line and structural plane, the energy released by rock mass failure induced by regional concentrated distribution of stress shows a space-time migration characteristic.

In engineering design problems, intervals refer to any kind of lack of information. This paper presents an improved entorpy-based methodology for a probabilistic representation of a stochastic quantity for which only sparse point data and/or interval data may be available. The combined entropy function is used to measure the uncertainty in data, which is evaluated from the non-parametric probability density function for sparse point data and the cumulative distribution function for interval data, Wherein the entire non-parametric distribution can be discretized at a finite number of points and the probability density values at these points can be inferred using the principle of maximum-entropy, thus avoiding the assumption of any particular distribution. The proposed improved Entorpy-based methodology is then employed in the attempt of interval uncertainty propagation, with the results compared with previous studies. Examples are provided to demonstrate the effectiveness of present method. The study reveals great potentials of the probabilistic method for the treatment of the uncertainty in presence of the sparse point data and/or interval data.

Affected by the geological concealment and complexity, there is a potential safety risk of mining induced damage due to insufficient grouting in fissures. Based on the analysis method of combining numerical simulation and microseismic monitoring, the grouting treatment effect of water conducting channel is analyzed based on the background of the grouting floor of 1612A working face in Zhangji Coal Mine. The influence of mining stress and the stability of grouting rock mass are revealed before and after grouting. The results show that: compared with the non-grouting, the abnormal stress area of surrounding rock decreases. The coupling is no longer connected to the working face. After 10 m away from the roadway side, the disturbance degree decreases with the increase of distance. Microseismic monitoring further verified the calculation results: the rock fracture signal “detours” in the grouting affected area. The number of microseismic events in surrounding rock area is small, and the grouted rock mass is in stable state.

Temperature difference and dew point are two important factors for moisture condensation of the storage grain.According to the large temperature humidity，storage temperature and humidity，grain temperature conditions and rice moisture during the discharge period of the finished grain rice，the reasons for moisture condensation were concluded.Using the relevant charts such as grain pile dew point approximation checklist，grain absolute humidity graph and atmospheric absolute humidity map，the main method of grain pile dew predicting were summarized and the feasible and effective treatment measures were provided which has positive significance for the safe storage of finished grain

To truly represent the developing changes and spatiotemporal effects of gas explosion in underground mine, this paper discussed the field modeling and visual simulation technology of mine gas explosion. Through analyzing the characteristics of various field parameters, space geometric field models, physical attribute field models, and meteorological parameter field models were established to describe mine engineering, ventilation network, and explosion disaster process, respectively. Based on the generated model class and simulation timing flow of gas explosion disaster field, OpenGL technology was adopted to visualize the model of gas explosion disaster field, which simulated the overpressure propagation process of gas explosion shockwave and dynamic spread process of disaster gas, thereby to reveal the developing changes of gas explosion parameters in time and space. Taking the gas explosion accident that occurred in a certain mine in China as an example, the disaster process was inferred to examine the availability of the mine gas explosion disaster field model. The research achievements in the paper not only embody the great engineering value of visual simulation technology in the field of safety engineering but also provide references for accident impact prediction, assessment, and emergency plan.

Abstract In this paper, we reconsider the clustering problem for image over-segmentation from a new perspective. We propose a novel search algorithm called “active search” which explicitly considers neighbor continuity. Based on this search method, we design a back-and-forth traversal strategy and a joint assignment and update step to speed up the algorithm. Compared to earlier methods, such as simple linear iterative clustering (SLIC) and its variants, which use fixed search regions and perform the assignment and the update steps separately, our novel scheme reduces the number of iterations required for convergence, and also provides better boundaries in the over-segmentation results. Extensive evaluation using the Berkeley segmentation benchmark verifies that our method outperforms competing methods under various evaluation metrics. In particular, our method is fastest, achieving approximately 30 fps for a 481 × 321 image on a single CPU core. To facilitate further research, our code is made publicly available.

The molecular structures of tetraaqua[N,N′-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide]sulfatomanganese(II) dihydrate, [Mn(SO4)(C17H13N5O2)(H2O)4]·2H2O or [Mn(H2L1)(SO4)(H2O)4]·2H2O, (I), and tetraaquabis[N,N′-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide]cadmium(II) sulfate tetrahydrate, [Cd(C17H13N5O2)2(H2O)4]SO4·4H2O or [Cd(H2O)4(H2L1)2]·SO4·4H2O, (II), both contain a central metal atom in a distorted octahedral geometry coordinated equatorially by four oxygen atoms from water molecules. In (I), the axial positions are occupied by a nitrogen atom from H2L1 and an oxygen atom from the sulfate anion, whereas in (II), the axial positions contain two nitrogen atoms from two different H2L1 ligands and the sulfate anion acts as the charge-balancing ion. π–π stacking between pyridine rings and a network of hydrogen bonds involving the water molecules and the sulfate anions play a crucial role in the molecular self-assembly of the two structures.

In order to study influence of adsorption pressure and grain size of coal sample on coal gas desorption, the No.3 coal in Sihe Coal Mine was selected as samples, and variety characteristics of gas desorption amount and desorption speed of coal samples with 0.17-0.25, 0.25-0.50, 1-3 mm grain sizes were analyzed at 1, 1.5, 3 MPa adsorption pressure by use of a gas isothermal adsorption and desorption experiment system. The experimental results show that under different adsorption pressure conditions, the gas desorption amount of the coal samples and initial desorption speed increase with the increase of adsorption on the whole. However, the influence of adsorption pressure on gas desorption amount and desorption speed of coal samples with 0.25-0.50 mm grain size is smaller than the other two grain sizes. The initial gas desorption amount of coal samples with smaller grain sizes is more than the one of the coal sample with bigger grain size under different adsorption pressure conditions, and the initial desorption speed is faster. But the gas desorption amount of the coal sample with 1.0-3.0 mm grain size is more than the one of the others under 1.5, 3 MPa adsorption pressure condition. Therefore, increasing adsorption pressure of coal sample or reducing grain size would cause increase of gas desorption amount and desorption speed.

Objective To compare the clinical effect of the zirconia inlay and gold alloy inlay in the restoration of the second class defect of molar with vital pulp.Methods 60 teeth were randomly divided into zirconia inlay group and gold alloy inlay group, with 30 teeth in each group. Evaluate the restoration effect in 2 group at 1-year follow-.Results At 1-year follow-up, according to US Public Health Service Criteria, the success rate in anatomy zirconia group was93.53%, which was statistically higher than that of the gold alloy group (P

Radar detection and tracking performance in the UHF-band can be influenced by the downlink signals of communication base stations. The polarimetric properties of interference from base stations are measured and analyzed as a basis for suppressing this type of interference by a polarization processing method. In this study, we establish signal models from the base station for dual-polarization UHF-band radar. We express the Probability Density Functions (PDF) of the estimated polarization ratio and degree of polarization in a closed form and use them to describe the statistical properties of the interference environment. We developed polarimetric radar reception experiments for the signals from both Single-Base Stations (SBS) and Multi-Base Stations (MBS). Experimental results proved that deterministic polarized descriptions are appropriate only for signals from SBS but not from MBS or from stations with a low DoP (Degree of Polarization). However, the proposed statistical method can be used to describe both SBS and MBS cases, which we demonstrated by comparing the theoretical models with real measurement data.